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* mysql: (mysql).               MySQL documentation.
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Copyright (C) 1997-2008 MySQL AB, 2009 Sun Microsystems, Inc. All
rights reserved. U.S. Government Rights - Commercial software.
Government users are subject to the Sun Microsystems, Inc. standard
license agreement and applicable provisions of the FAR and its
supplements. Use is subject to license terms. Sun, Sun Microsystems,
the Sun logo, Java, Solaris, StarOffice, MySQL Enterprise Monitor 2.0,
MySQL logo(tm) and MySQL(tm) are trademarks or registered trademarks of
Sun Microsystems, Inc. in the U.S. and other countries. UNIX is a
registered trademark in the U.S. and other countries, exclusively
licensed through X/Open Company, Ltd.

Copyright (C) 1997-2008 MySQL AB, 2009 Sun Microsystems, Inc.  Tous
droits re'serve's. L'utilisation est soumise aux termes du contrat de
licence.Sun, Sun Microsystems, le logo Sun, Java, Solaris, StarOffice,
MySQL Enterprise Monitor 2.0, MySQL logo(tm) et MySQL(tm) sont des
marques de fabrique ou des marques de'pose'es de Sun Microsystems, Inc.
aux Etats-Unis et dans d'autres pays. UNIX est une marque de'pose'e aux
Etats-Unis et dans d'autres pays et licencie'e exlusivement par X/Open
Company, Ltd.

This documentation is NOT distributed under a GPL license. Use of this
documentation is subject to the following terms: You may create a
printed copy of this documentation solely for your own personal use.
Conversion to other formats is allowed as long as the actual content is
not altered or edited in any way. You shall not publish or distribute
this documentation in any form or on any media, except if you
distribute the documentation in a manner similar to how Sun
disseminates it (that is, electronically for download on a Web site
with the software) or on a CD-ROM or similar medium, provided however
that the documentation is disseminated together with the software on
the same medium. Any other use, such as any dissemination of printed
copies or use of this documentation, in whole or in part, in another
publication, requires the prior written consent from an authorized
representative of Sun Microsystems, Inc.  Sun Microsystems, Inc. and
MySQL AB reserve any and all rights to this documentation not expressly
granted above.

For more information on the terms of this license, for details on how
the MySQL documentation is built and produced, or if you are interested
in doing a translation, please contact the Documentation Team
(http://www.mysql.com/company/contact/).

For additional licensing information, including licenses for libraries
used by MySQL, see *Note Top::.

If you want help with using MySQL, please visit either the MySQL Forums
(http://forums.mysql.com) or MySQL Mailing Lists
(http://lists.mysql.com) where you can discuss your issues with other
MySQL users.

For additional documentation on MySQL products, including translations
of the documentation into other languages, and downloadable versions in
variety of formats, including HTML, CHM, and PDF formats, see MySQL
Documentation Library (http://dev.mysql.com/doc).

This is the Reference Manual for the MySQL Database System, version
6.0, through release 6.0.12. It is not intended for use with older
versions of the MySQL software due to the many functional and other
differences between MySQL 6.0 and previous versions. If you are using
an earlier release of the MySQL software, please refer to the `MySQL
5.1 Reference Manual' (http://dev.mysql.com/doc/refman/5.1/en/), which
covers the 5.1 series of MySQL software releases, `MySQL 5.0 Manual'
(http://dev.mysql.com/doc/refman/5.0/en/), which covers MySQL 5.0
releases, or to `MySQL 3.23, 4.0, 4.1 Reference Manual'
(http://dev.mysql.com/doc/refman/4.1/en/), which covers the 3.23, 4.0,
and 4.1 series of MySQL software releases. Differences between minor
versions of MySQL 6.0 are noted in the present text with reference to
release numbers (6.0.X).

* Menu:

* introduction::                 General Information
* installing::                   Installing and Upgrading MySQL
* tutorial::                     Tutorial
* programs::                     MySQL Programs
* server-administration::        MySQL Server Administration
* backup-and-recovery::          Backup and Recovery
* optimization::                 Optimization
* language-structure::           Language Structure
* internationalization-localization::  Internationalization and Localization
* data-types::                   Data Types
* functions::                    Functions and Operators
* sql-syntax::                   SQL Statement Syntax
* storage-engines::              Storage Engines
* ha-overview::                  High Availability and Scalability
* mem-introduction::             MySQL Enterprise Monitor
* replication::                  Replication
* partitioning::                 Partitioning
* stored-programs-views::        Stored Programs and Views
* information-schema::           `INFORMATION_SCHEMA' Tables
* connectors-apis::              Connectors and APIs
* extending-mysql::              Extending MySQL
* faqs::                         MySQL 6.0 Frequently Asked Questions
* error-handling::               Errors, Error Codes, and Common Problems
* news::                         MySQL Change History
* restrictions::                 Restrictions and Limits


File: manual.info,  Node: introduction,  Next: installing,  Prev: Top,  Up: Top

1 General Information
*********************

* Menu:

* manual-info::                  About This Manual
* manual-conventions::           Typographical and Syntax Conventions
* what-is::                      Overview of the MySQL Database Management System
* roadmap::                      MySQL Development Roadmap
* information-sources::          MySQL Information Sources
* bug-reports::                  How to Report Bugs or Problems
* compatibility::                MySQL Standards Compliance
* credits::                      Credits

The MySQL(R) software delivers a very fast, multi-threaded, multi-user,
and robust SQL (Structured Query Language) database server. MySQL
Server is intended for mission-critical, heavy-load production systems
as well as for embedding into mass-deployed software. MySQL is a
registered trademark of MySQL AB.

The MySQL software is Dual Licensed. Users can choose to use the MySQL
software as an Open Source product under the terms of the GNU General
Public License (`http://www.fsf.org/licenses/') or can purchase a
standard commercial license from MySQL AB. See
`http://www.mysql.com/company/legal/licensing/' for more information on
our licensing policies.

The following list describes some sections of particular interest in
this manual:

   * For a discussion about the capabilities of the MySQL Database
     Server, see *Note features::.

   * For future plans, see *Note roadmap::.

   * For installation instructions, see *Note installing::.  For
     information about upgrading MySQL, see *Note upgrade::.

   * For a tutorial introduction to the MySQL Database Server, see
     *Note tutorial::.

   * For information about configuring and administering MySQL Server,
     see *Note server-administration::.

   * For information about setting up replication servers, see *Note
     replication::.

   * For answers to a number of questions that are often asked
     concerning the MySQL Database Server and its capabilities, see
     *Note faqs::.

   * For a list of currently known bugs and misfeatures, see *Note
     bugs::.

   * For a list of all the contributors to this project, see *Note
     credits::.

   * For a history of new features and bugfixes, see *Note news::.

   * For tips on porting the MySQL Database Software to new
     architectures or operating systems, see MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * For benchmarking information, see the `sql-bench' benchmarking
     directory in your MySQL distribution.

*Important*:

To report errors (often called `bugs'), please use the instructions at
*Note bug-reports::.

If you have found a sensitive security bug in MySQL Server, please let
us know immediately by sending an email message to <security@mysql.com>.


File: manual.info,  Node: manual-info,  Next: manual-conventions,  Prev: introduction,  Up: introduction

1.1 About This Manual
=====================

This is the Reference Manual for the MySQL Database System, version
6.0, through release 6.0.12. It is not intended for use with older
versions of the MySQL software due to the many functional and other
differences between MySQL 6.0 and previous versions. If you are using an
earlier release of the MySQL software, please refer to the `MySQL 5.1
Reference Manual' (http://dev.mysql.com/doc/refman/5.1/en/), which
covers the 5.1 series of MySQL software releases, `MySQL 5.0 Manual'
(http://dev.mysql.com/doc/refman/5.0/en/), which covers MySQL 5.0
releases, or to `MySQL 3.23, 4.0, 4.1 Reference Manual'
(http://dev.mysql.com/doc/refman/4.1/en/), which covers the 3.23, 4.0,
and 4.1 series of MySQL software releases.  Differences between minor
versions of MySQL 6.0 are noted in the present text with reference to
release numbers (6.0.X).

Because this manual serves as a reference, it does not provide general
instruction on SQL or relational database concepts. It also does not
teach you how to use your operating system or command-line interpreter.

The MySQL Database Software is under constant development, and the
Reference Manual is updated frequently as well. The most recent version
of the manual is available online in searchable form at
`http://dev.mysql.com/doc/'. Other formats also are available there,
including HTML, PDF, and Windows CHM versions.

The Reference Manual source files are written in DocBook XML format.
The HTML version and other formats are produced automatically,
primarily using the DocBook XSL stylesheets. For information about
DocBook, see `http://docbook.org/'

The DocBook XML sources of this manual are available from
`http://dev.mysql.com/tech-resources/sources.html'.  You can check out
a copy of the documentation repository with this command:

     svn checkout http://svn.mysql.com/svnpublic/mysqldoc/

If you have questions about using MySQL, you can ask them using our
mailing lists or forums. See *Note mailing-lists::, and *Note forums::.
If you have suggestions concerning additions or corrections to the
manual itself, please send them to the Documentation Team
(http://www.mysql.com/company/contact/).

This manual was originally written by David Axmark and Michael `Monty'
Widenius. It is maintained by the MySQL Documentation Team, consisting
of Paul DuBois, Stefan Hinz, Jon Stephens, Martin MC Brown, and Tony
Bedford.


File: manual.info,  Node: manual-conventions,  Next: what-is,  Prev: manual-info,  Up: introduction

1.2 Typographical and Syntax Conventions
========================================

This manual uses certain typographical conventions:

   * `Text in this style' is used for SQL statements; database, table,
     and column names; program listings and source code; and
     environment variables. Example: `To reload the grant tables, use
     the *Note `FLUSH PRIVILEGES': flush. statement.'

   * Text in this style indicates input that you type in examples.

   * `Text in this style' indicates the names of executable programs
     and scripts, examples being *Note `mysql': mysql. (the MySQL
     command line client program) and *Note `mysqld': mysqld. (the
     MySQL server executable).

   * TEXT IN THIS STYLE is used for variable input for which you should
     substitute a value of your own choosing.

   * File names and directory names are written like this: `The global
     `my.cnf' file is located in the `/etc' directory.'

   * Character sequences are written like this: `To specify a wildcard,
     use the ``%'' character.'

   * _Text in this style_ is used for emphasis.

   * *Text in this style* is used in table headings and to convey
     especially strong emphasis.

When commands are shown that are meant to be executed from within a
particular program, the prompt shown preceding the command indicates
which command to use. For example, `shell>' indicates a command that
you execute from your login shell, and `mysql>' indicates a statement
that you execute from the *Note `mysql': mysql. client program:

     shell> type a shell command here
     root-shell> type a shell command as ROOT here
     mysql> type a mysql statement here

In some areas different systems may be distinguished from each other to
show that commands should be executed in two different environments.
For example, while working with replication the commands might be
prefixed with `master' and `slave':

     master> type a mysql command on the replication master here
     slave> type a mysql command on the replication slave here

The `shell' is your command interpreter. On Unix, this is typically a
program such as `sh', `csh', or `bash'. On Windows, the equivalent
program is `command.com' or `cmd.exe', typically run in a console
window.

When you enter a command or statement shown in an example, do not type
the prompt shown in the example.

Database, table, and column names must often be substituted into
statements. To indicate that such substitution is necessary, this
manual uses DB_NAME, TBL_NAME, and COL_NAME. For example, you might see
a statement like this:

     mysql> SELECT COL_NAME FROM DB_NAME.TBL_NAME;

This means that if you were to enter a similar statement, you would
supply your own database, table, and column names, perhaps like this:

     mysql> SELECT author_name FROM biblio_db.author_list;

SQL keywords are not case sensitive and may be written in any
lettercase. This manual uses uppercase.

In syntax descriptions, square brackets (``['' and ``]'') indicate
optional words or clauses. For example, in the following statement, `IF
EXISTS' is optional:

     DROP TABLE [IF EXISTS] TBL_NAME

When a syntax element consists of a number of alternatives, the
alternatives are separated by vertical bars (``|''). When one member
from a set of choices _may_ be chosen, the alternatives are listed
within square brackets (``['' and ``]''):

     TRIM([[BOTH | LEADING | TRAILING] [REMSTR] FROM] STR)

When one member from a set of choices _must_ be chosen, the
alternatives are listed within braces (``{'' and ``}''):

     {DESCRIBE | DESC} TBL_NAME [COL_NAME | WILD]

An ellipsis (`...') indicates the omission of a section of a statement,
typically to provide a shorter version of more complex syntax. For
example, *Note `SELECT ... INTO OUTFILE': select. is shorthand for the
form of *Note `SELECT': select. statement that has an `INTO OUTFILE'
clause following other parts of the statement.

An ellipsis can also indicate that the preceding syntax element of a
statement may be repeated. In the following example, multiple
RESET_OPTION values may be given, with each of those after the first
preceded by commas:

     RESET RESET_OPTION [,RESET_OPTION] ...

Commands for setting shell variables are shown using Bourne shell
syntax. For example, the sequence to set the `CC' environment variable
and run the `configure' command looks like this in Bourne shell syntax:

     shell> CC=gcc ./configure

If you are using `csh' or `tcsh', you must issue commands somewhat
differently:

     shell> setenv CC gcc
     shell> ./configure


File: manual.info,  Node: what-is,  Next: roadmap,  Prev: manual-conventions,  Up: introduction

1.3 Overview of the MySQL Database Management System
====================================================

* Menu:

* what-is-mysql::                What is MySQL?
* history::                      History of MySQL
* features::                     The Main Features of MySQL


File: manual.info,  Node: what-is-mysql,  Next: history,  Prev: what-is,  Up: what-is

1.3.1 What is MySQL?
--------------------

MySQL, the most popular Open Source SQL database management system, is
developed, distributed, and supported by MySQL AB.  MySQL AB is a
commercial company, founded by the MySQL developers.  It is a second
generation Open Source company that unites Open Source values and
methodology with a successful business model.

The MySQL Web site (`http://www.mysql.com/') provides the latest
information about MySQL software and MySQL AB.

   * MySQL is a database management system.

     A database is a structured collection of data. It may be anything
     from a simple shopping list to a picture gallery or the vast
     amounts of information in a corporate network. To add, access, and
     process data stored in a computer database, you need a database
     management system such as MySQL Server.  Since computers are very
     good at handling large amounts of data, database management
     systems play a central role in computing, as standalone utilities,
     or as parts of other applications.

   * MySQL is a relational database management system.

     A relational database stores data in separate tables rather than
     putting all the data in one big storeroom. This adds speed and
     flexibility. The SQL part of `MySQL' stands for `Structured Query
     Language.' SQL is the most common standardized language used to
     access databases and is defined by the ANSI/ISO SQL Standard. The
     SQL standard has been evolving since 1986 and several versions
     exist. In this manual, `SQL-92' refers to the standard released in
     1992, `SQL:1999' refers to the standard released in 1999, and
     `SQL:2003' refers to the current version of the standard. We use
     the phrase `the SQL standard' to mean the current version of the
     SQL Standard at any time.

   * MySQL software is Open Source.

     Open Source means that it is possible for anyone to use and modify
     the software. Anybody can download the MySQL software from the
     Internet and use it without paying anything. If you wish, you may
     study the source code and change it to suit your needs. The MySQL
     software uses the GPL (GNU General Public License),
     `http://www.fsf.org/licenses/', to define what you may and may not
     do with the software in different situations. If you feel
     uncomfortable with the GPL or need to embed MySQL code into a
     commercial application, you can buy a commercially licensed
     version from us. See the MySQL Licensing Overview for more
     information (`http://www.mysql.com/company/legal/licensing/').

   * The MySQL Database Server is very fast, reliable, and easy to use.

     If that is what you are looking for, you should give it a try.
     MySQL Server also has a practical set of features developed in
     close cooperation with our users. You can find a performance
     comparison of MySQL Server with other database managers on our
     benchmark page. See *Note mysql-benchmarks::.

     MySQL Server was originally developed to handle large databases
     much faster than existing solutions and has been successfully used
     in highly demanding production environments for several years.
     Although under constant development, MySQL Server today offers a
     rich and useful set of functions. Its connectivity, speed, and
     security make MySQL Server highly suited for accessing databases
     on the Internet.

   * MySQL Server works in client/server or embedded systems.

     The MySQL Database Software is a client/server system that
     consists of a multi-threaded SQL server that supports different
     backends, several different client programs and libraries,
     administrative tools, and a wide range of application programming
     interfaces (APIs).

     We also provide MySQL Server as an embedded multi-threaded library
     that you can link into your application to get a smaller, faster,
     easier-to-manage standalone product.

   * A large amount of contributed MySQL software is available.

     It is very likely that your favorite application or language
     supports the MySQL Database Server.

The official way to pronounce `MySQL' is `My Ess Que Ell' (not `my
sequel'), but we do not mind if you pronounce it as `my sequel' or in
some other localized way.


File: manual.info,  Node: history,  Next: features,  Prev: what-is-mysql,  Up: what-is

1.3.2 History of MySQL
----------------------

We started out with the intention of using the `mSQL' database system
to connect to our tables using our own fast low-level (ISAM) routines.
However, after some testing, we came to the conclusion that `mSQL' was
not fast enough or flexible enough for our needs. This resulted in a
new SQL interface to our database but with almost the same API
interface as `mSQL'. This API was designed to allow third-party code
that was written for use with `mSQL' to be ported easily for use with
MySQL.

MySQL is named after co-founder Monty Widenius's daughter, My.

The name of the MySQL Dolphin (our logo) is `Sakila,' which was chosen
by the founders of MySQL AB from a huge list of names suggested by
users in our `Name the Dolphin' contest. The winning name was submitted
by Ambrose Twebaze, an Open Source software developer from Swaziland,
Africa. According to Ambrose, the feminine name Sakila has its roots in
SiSwati, the local language of Swaziland. Sakila is also the name of a
town in Arusha, Tanzania, near Ambrose's country of origin, Uganda.


File: manual.info,  Node: features,  Prev: history,  Up: what-is

1.3.3 The Main Features of MySQL
--------------------------------

This section describes some of the important characteristics of the
MySQL Database Software. See also *Note roadmap::, for more information
about current and upcoming features. In most respects, it applies to
all versions of MySQL. For information about features as they are
introduced into MySQL on a series-specific basis, see the `In a
Nutshell' section of the appropriate Manual:

   * MySQL 4.0 and 4.1: MySQL 4.0 in a Nutshell
     (http://dev.mysql.com/doc/refman/4.1/en/mysql-4-0-nutshell.html),
     and MySQL 4.1 in a Nutshell
     (http://dev.mysql.com/doc/refman/4.1/en/mysql-nutshell.html).

   * MySQL 5.0: MySQL 5.0 in a Nutshell
     (http://dev.mysql.com/doc/refman/5.0/en/mysql-nutshell.html).

   * MySQL 5.1: MySQL 5.1 in a Nutshell
     (http://dev.mysql.com/doc/refman/5.1/en/mysql-nutshell.html).

   * MySQL 6.0: *Note MySQL 6.0 in a Nutshell: mysql-nutshell.

Internals and Portability:

   * Written in C and C++.

   * Tested with a broad range of different compilers.

   * Works on many different platforms. See *Note which-os::.

   * Uses GNU Automake, Autoconf, and Libtool for portability.

   * The MySQL Server design is multi-layered with independent modules.

   * Fully multi-threaded using kernel threads. It can easily use
     multiple CPUs if they are available.

   * Provides transactional and non-transactional storage engines.

   * Uses very fast B-tree disk tables (`MyISAM') with index
     compression.

   * Relatively easy to add other storage engines. This is useful if
     you want to provide an SQL interface for an in-house database.

   * A very fast thread-based memory allocation system.

   * Very fast joins using an optimized one-sweep multi-join.

   * In-memory hash tables, which are used as temporary tables.

   * SQL functions are implemented using a highly optimized class
     library and should be as fast as possible. Usually there is no
     memory allocation at all after query initialization.

   * The MySQL code is tested with Purify (a commercial memory leakage
     detector) as well as with Valgrind, a GPL tool
     (`http://developer.kde.org/~sewardj/').

   * The server is available as a separate program for use in a
     client/server networked environment. It is also available as a
     library that can be embedded (linked) into standalone
     applications. Such applications can be used in isolation or in
     environments where no network is available.

Data Types:

   * Many data types: signed/unsigned integers 1, 2, 3, 4, and 8 bytes
     long, *Note `FLOAT': numeric-types, *Note `DOUBLE': numeric-types,
     *Note `CHAR': char, *Note `VARCHAR': char, *Note `TEXT': blob,
     *Note `BLOB': blob, *Note `DATE': datetime, *Note `TIME': time,
     *Note `DATETIME': datetime, *Note `TIMESTAMP': datetime, *Note
     `YEAR': year, *Note `SET': set, *Note `ENUM': enum, and OpenGIS
     spatial types. See *Note data-types::.

   * Fixed-length and variable-length records.

Statements and Functions:

   * Full operator and function support in the *Note `SELECT': select.
     list and `WHERE' clause of queries. For example:

          mysql> SELECT CONCAT(first_name, ' ', last_name)
              -> FROM citizen
              -> WHERE income/dependents > 10000 AND age > 30;

   * Full support for SQL `GROUP BY' and `ORDER BY' clauses. Support
     for group functions (`COUNT()', `COUNT(DISTINCT ...)', `AVG()',
     `STD()', `SUM()', `MAX()', `MIN()', and `GROUP_CONCAT()').

   * Support for `LEFT OUTER JOIN' and `RIGHT OUTER JOIN' with both
     standard SQL and ODBC syntax.

   * Support for aliases on tables and columns as required by standard
     SQL.

   * *Note `DELETE': delete, *Note `INSERT': insert, *Note `REPLACE':
     replace, and *Note `UPDATE': update. return the number of rows
     that were changed (affected). It is possible to return the number
     of rows matched instead by setting a flag when connecting to the
     server.

   * The MySQL-specific *Note `SHOW': show.  statement can be used to
     retrieve information about databases, storage engines, tables, and
     indexes. MySQL 5.0 adds support for the `INFORMATION_SCHEMA'
     database, implemented according to standard SQL.

   * The *Note `EXPLAIN': explain. statement can be used to determine
     how the optimizer resolves a query.

   * Function names do not clash with table or column names. For
     example, `ABS' is a valid column name. The only restriction is
     that for a function call, no spaces are allowed between the
     function name and the ``('' that follows it. See *Note
     reserved-words::.

   * You can refer to tables from different databases in the same
     statement.

Security:

   * A privilege and password system that is very flexible and secure,
     and that allows host-based verification.

   * Passwords are secure because all password traffic is encrypted
     when you connect to a server.

Scalability and Limits:

   * Handles large databases. We use MySQL Server with databases that
     contain 50 million records. We also know of users who use MySQL
     Server with 60,000 tables and about 5,000,000,000 rows.

   * Up to 64 indexes per table are allowed (32 before MySQL 4.1.2).
     Each index may consist of 1 to 16 columns or parts of columns. The
     maximum index width is 1000 bytes (767 for `InnoDB'); before MySQL
     4.1.2, the limit is 500 bytes. An index may use a prefix of a
     column for *Note `CHAR': char, *Note `VARCHAR': char, *Note
     `BLOB': blob, or *Note `TEXT': blob. column types.

Connectivity:

   * Clients can connect to MySQL Server using several protocols:

        * Clients can connect using TCP/IP sockets on any platform.

        * On Windows systems in the NT family (NT, 2000, XP, 2003, or
          Vista), clients can connect using named pipes if the server
          is started with the `--enable-named-pipe' option.  In MySQL
          4.1 and higher, Windows servers also support shared-memory
          connections if started with the `--shared-memory' option.
          Clients can connect through shared memory by using the
          `--protocol=memory' option.

        * On Unix systems, clients can connect using Unix domain socket
          files.

   * MySQL client programs can be written in many languages. A client
     library written in C is available for clients written in C or C++,
     or for any language that provides C bindings.

   * APIs for C, C++, Eiffel, Java, Perl, PHP, Python, Ruby, and Tcl
     are available, allowing MySQL clients to be written in many
     languages. See *Note connectors-apis::.

   * The Connector/ODBC (MyODBC) interface provides MySQL support for
     client programs that use ODBC (Open Database Connectivity)
     connections. For example, you can use MS Access to connect to your
     MySQL server. Clients can be run on Windows or Unix.  MyODBC
     source is available. All ODBC 2.5 functions are supported, as are
     many others. See *Note connector-odbc::.

   * The Connector/J interface provides MySQL support for Java client
     programs that use JDBC connections. Clients can be run on Windows
     or Unix. Connector/J source is available. See *Note connector-j::.

   * MySQL Connector/NET enables developers to easily create .NET
     applications that require secure, high-performance data
     connectivity with MySQL. It implements the required ADO.NET
     interfaces and integrates into ADO.NET aware tools. Developers can
     build applications using their choice of .NET languages.  MySQL
     Connector/NET is a fully managed ADO.NET driver written in 100%
     pure C#. See *Note connector-net::.

Localization:

   * The server can provide error messages to clients in many
     languages. See *Note error-message-language::.

   * Full support for several different character sets, including
     `latin1' (cp1252), `german', `big5', `ujis', and more.  For
     example, the Scandinavian characters ``aa'', ``a"'' and ``o"'' are
     allowed in table and column names. Unicode support is available as
     of MySQL 4.1.

   * All data is saved in the chosen character set.

   * Sorting and comparisons are done according to the chosen character
     set and collation (using `latin1' and Swedish collation by
     default). It is possible to change this when the MySQL server is
     started. To see an example of very advanced sorting, look at the
     Czech sorting code. MySQL Server supports many different character
     sets that can be specified at compile time and runtime.

   * As of MySQL 4.1, the server time zone can be changed dynamically,
     and individual clients can specify their own time zone. *Note
     time-zone-support::.

MySQL Enterprise

For assistance in getting optimal performance from your MySQL server
subscribe to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/'.

Clients and Tools:

   * MySQL AB provides several client and utility programs. These
     include both command-line programs such as *Note `mysqldump':
     mysqldump. and *Note `mysqladmin': mysqladmin, and graphical
     programs such as MySQL Administrator and MySQL Query Browser.

   * MySQL Server has built-in support for SQL statements to check,
     optimize, and repair tables. These statements are available from
     the command line through the *Note `mysqlcheck': mysqlcheck.
     client. MySQL also includes *Note `myisamchk': myisamchk, a very
     fast command-line utility for performing these operations on
     `MyISAM' tables. See *Note programs::.

   * MySQL programs can be invoked with the `--help' or `-?' option to
     obtain online assistance.


File: manual.info,  Node: roadmap,  Next: information-sources,  Prev: what-is,  Up: introduction

1.4 MySQL Development Roadmap
=============================

* Menu:

* mysql-nutshell::               What Is New in MySQL 6.0

This section describes the general MySQL development roadmap, provides
an overview about features that have been implemented in previous
series and that are new in this current release series (6.0), and an
overview about upcoming additions or changes in the next release series
(6.1).

The maturity level of the release series covered in this manual (6.0)
is alpha. Information about maturity levels can be found in *Note
choosing-version::.

Before upgrading from one release series to the next, please see the
notes in *Note upgrade::.

The most requested features and the versions in which they were
implemented or are scheduled for implementation are summarized in the
following table.

*Feature*              *MySQL Series*
Unions                 4.0
Subqueries             4.1
R-trees                4.1 (for the `MyISAM' storage engine)
Stored procedures      5.0
Views                  5.0
Cursors                5.0
XA transactions        5.0
Triggers               5.0 and 5.1
Event scheduler        5.1
Partitioning           5.1
Pluggable storage      5.1
engine API             
Plugin API             5.1
Row-based replication  5.1
Server log tables      5.1
Foreign keys           6.x (implemented in 3.23 for `InnoDB')


File: manual.info,  Node: mysql-nutshell,  Prev: roadmap,  Up: roadmap

1.4.1 What Is New in MySQL 6.0
------------------------------

*Note*:

This section remains subject to change as long as MySQL 6.0 development
is in its early stages.

The following features have been or are expected to be added to MySQL
6.0:

   * The new `Falcon' transactional storage engine (see *Note
     se-falcon::).

   * Support for additional Unicode character sets: `utf16', `utf32',
     and 4-byte `utf8'. These character sets support supplementary
     Unicode characters; that is, characters outside the Basic
     Multilingual Plane (BMP).

   * *Note `BACKUP DATABASE': backup-database. and *Note `RESTORE':
     restore. statements for backup and restore operations. See *Note
     backup-database-restore::.

   * Improvements in the `INFORMATION_SCHEMA' database, with the
     addition of the *Note `INFORMATION_SCHEMA.PARAMETERS':
     parameters-table.  table, and new columns added to *Note
     `INFORMATION_SCHEMA.ROUTINES': routines-table.  (see *Note
     parameters-table::, and *Note routines-table::).

   * Optimizer enhancements for faster subqueries and joins, including
     batched index access of table rows for sequences of disjoint
     ranges by the `MyISAM' and `InnoDB' storage engines.

   * The syntax for the *Note `LOCK TABLES': lock-tables. statement has
     been extended to support transactional table locks that do not
     commit transactions automatically. Following `LOCK TABLES ... IN
     SHARE MODE' or `LOCK TABLES ... IN EXCLUSIVE MODE', you can access
     tables not mentioned in the *Note `LOCK TABLES': lock-tables.
     statement. You can also issue *Note `LOCK TABLES': lock-tables.
     statements that acquire transactional locks many times in
     succession, adding additional tables to the locked set, and
     without unlocking any tables that were locked previously. When
     using *Note `LOCK TABLES': lock-tables. with `IN SHARE MODE' or
     `IN EXCLUSIVE MODE', tables are not unlocked until the transaction
     ends.

     Transactional locks acquired with *Note `LOCK TABLES':
     lock-tables. are released when the transaction ends, either
     explicitly with *Note `COMMIT': commit. or *Note `ROLLBACK':
     commit, or implicitly due to a statement that causes implicit
     commit or because the connection ends.  *Note implicit-commit::,
     lists those statements that cause implicit commit.

     The behavior of *Note `LOCK TABLES': lock-tables.  remains
     unchanged for `READ' or `WRITE' locks (that is, when not using `IN
     SHARE MODE' or `IN EXCLUSIVE MODE').

   * Enhancements to XML functionality, including a new *Note `LOAD
     XML': load-xml. statement (see *Note load-xml::).

   * Supports for an interface for semisynchronous replication: A
     commit performed on the master side blocks before returning to the
     session that performed the transaction until at least one slave
     acknowleges that it has received and logged the events for the
     transaction. Semisynchronous replication is implemented through an
     optional plugin component. See *Note replication-semisync::

   * Support for the SQL standard *Note `SIGNAL': signal. and *Note
     `RESIGNAL': resignal. statements. See *Note signal-resignal::.

   * *Note `RESET SLAVE': reset-slave. no longer changes replication
     connection parameters; previously, it reset them to the values
     specified on the command line (see *Note reset-slave::).

   * Support for extended comments for tables, columns, and indexes.

The following constructs are deprecated and have been removed in MySQL
6.0. Where alternatives are shown, applications should be updated to
use them.

   * The `table_type'
     (http://dev.mysql.com/doc/refman/5.1/en/server-system-variables.html#sysvar_table_type)
     system variable (use `storage_engine').

   * The `TYPE' table option to specify the storage engine for *Note
     `CREATE TABLE': create-table. or *Note `ALTER TABLE': alter-table.
     (use `ENGINE').

   * The `SHOW TABLE TYPES' SQL statement (use *Note `SHOW ENGINES':
     show-engines.).

   * The `log_bin_trust_routine_creators' variable (use
     `log_bin_trust_function_creators').

   * *Note `TIMESTAMP(N)': datetime.: The ability to specify a display
     width of N (use without N).

   * The `SHOW INNODB STATUS'
     (http://dev.mysql.com/doc/refman/5.1/en/show-innodb-status.html)
     and `SHOW MUTEX STATUS' SQL statements (use *Note `SHOW ENGINE
     INNODB STATUS': show-engine. for both of these).

   * The `LOAD TABLE ... FROM MASTER' and `LOAD DATA FROM MASTER' SQL
     statements.

   * The `SHOW PLUGIN' SQL statement (use *Note `SHOW PLUGINS':
     show-plugins.).

   * The `BACKUP TABLE'
     (http://dev.mysql.com/doc/refman/5.1/en/backup-table.html) and The
     `RESTORE TABLE'
     (http://dev.mysql.com/doc/refman/5.1/en/restore-table.html) SQL
     statements.

   * The `--master-XXX' server options to set replication parameters
     (use the *Note `CHANGE MASTER TO': change-master-to. statement
     instead): `--master-host', `--master-user', `--master-password ',
     `--master-port', `--master-connect-retry', `--master-ssl',
     `--master-ssl-ca', `--master-ssl-capath', `--master-ssl-cert',
     `--master-ssl-cipher', `--master-ssl-key'.


File: manual.info,  Node: information-sources,  Next: bug-reports,  Prev: roadmap,  Up: introduction

1.5 MySQL Information Sources
=============================

* Menu:

* mailing-lists::                MySQL Mailing Lists
* forums::                       MySQL Community Support at the MySQL Forums
* irc::                          MySQL Community Support on Internet Relay Chat (IRC)
* mysql-enterprise-information::  MySQL Enterprise

This section lists sources of additional information that you may find
helpful, such as the MySQL mailing lists and user forums, and Internet
Relay Chat.


File: manual.info,  Node: mailing-lists,  Next: forums,  Prev: information-sources,  Up: information-sources

1.5.1 MySQL Mailing Lists
-------------------------

* Menu:

* mailing-list-use::             Guidelines for Using the Mailing Lists

This section introduces the MySQL mailing lists and provides guidelines
as to how the lists should be used. When you subscribe to a mailing
list, you receive all postings to the list as email messages. You can
also send your own questions and answers to the list.

To subscribe to or unsubscribe from any of the mailing lists described
in this section, visit `http://lists.mysql.com/'. For most of them, you
can select the regular version of the list where you get individual
messages, or a digest version where you get one large message per day.

Please _do not_ send messages about subscribing or unsubscribing to any
of the mailing lists, because such messages are distributed
automatically to thousands of other users.

Your local site may have many subscribers to a MySQL mailing list.  If
so, the site may have a local mailing list, so that messages sent from
`lists.mysql.com' to your site are propagated to the local list. In
such cases, please contact your system administrator to be added to or
dropped from the local MySQL list.

If you wish to have traffic for a mailing list go to a separate mailbox
in your mail program, set up a filter based on the message headers. You
can use either the `List-ID:' or `Delivered-To:' headers to identify
list messages.

The MySQL mailing lists are as follows:

   * `announce'

     This list is for announcements of new versions of MySQL and
     related programs. This is a low-volume list to which all MySQL
     users should subscribe.

   * `mysql'

     This is the main list for general MySQL discussion. Please note
     that some topics are better discussed on the more-specialized
     lists. If you post to the wrong list, you may not get an answer.

   * `bugs'

     This list is for people who want to stay informed about issues
     reported since the last release of MySQL or who want to be
     actively involved in the process of bug hunting and fixing.  See
     *Note bug-reports::.

   * `internals'

     This list is for people who work on the MySQL code. This is also
     the forum for discussions on MySQL development and for posting
     patches.

   * `mysqldoc'

     This list is for people who work on the MySQL documentation:
     people from MySQL AB, translators, and other community members.

   * `benchmarks'

     This list is for anyone interested in performance issues.
     Discussions concentrate on database performance (not limited to
     MySQL), but also include broader categories such as performance of
     the kernel, file system, disk system, and so on.

   * `packagers'

     This list is for discussions on packaging and distributing MySQL.
     This is the forum used by distribution maintainers to exchange
     ideas on packaging MySQL and on ensuring that MySQL looks and
     feels as similar as possible on all supported platforms and
     operating systems.

   * `java'

     This list is for discussions about the MySQL server and Java.  It
     is mostly used to discuss JDBC drivers such as MySQL Connector/J.

   * `win32'

     This list is for all topics concerning the MySQL software on
     Microsoft operating systems, such as Windows 9x, Me, NT, 2000, XP,
     and 2003.

   * `myodbc'

     This list is for all topics concerning connecting to the MySQL
     server with ODBC.

   * `gui-tools'

     This list is for all topics concerning MySQL graphical user
     interface tools such as `MySQL Administrator' and `MySQL Query
     Browser'.

   * `cluster'

     This list is for discussion of MySQL Cluster.

   * `dotnet'

     This list is for discussion of the MySQL server and the .NET
     platform. It is mostly related to MySQL Connector/Net.

   * `plusplus'

     This list is for all topics concerning programming with the C++
     API for MySQL.

   * `perl'

     This list is for all topics concerning Perl support for MySQL with
     `DBD::mysql'.

If you're unable to get an answer to your questions from a MySQL
mailing list or forum, one option is to purchase support from Sun
Microsystems, Inc. This puts you in direct contact with MySQL
developers.

The following table shows some MySQL mailing lists in languages other
than English. These lists are not operated by Sun Microsystems, Inc.

   * `<mysql-france-subscribe@yahoogroups.com>'

     A French mailing list.

   * `<list@tinc.net>'

     A Korean mailing list. To subscribe, email `subscribe mysql
     your@email.address' to this list.

   * `<mysql-de-request@lists.4t2.com>'

     A German mailing list. To subscribe, email `subscribe mysql-de
     your@email.address' to this list. You can find information about
     this mailing list at `http://www.4t2.com/mysql/'.

   * `<mysql-br-request@listas.linkway.com.br>'

     A Portuguese mailing list. To subscribe, email `subscribe mysql-br
     your@email.address' to this list.

   * `<mysql-alta@elistas.net>'

     A Spanish mailing list. To subscribe, email `subscribe mysql
     your@email.address' to this list.


File: manual.info,  Node: mailing-list-use,  Prev: mailing-lists,  Up: mailing-lists

1.5.1.1 Guidelines for Using the Mailing Lists
..............................................

Please do not post mail messages from your browser with HTML mode
turned on. Many users do not read mail with a browser.

When you answer a question sent to a mailing list, if you consider your
answer to have broad interest, you may want to post it to the list
instead of replying directly to the individual who asked. Try to make
your answer general enough that people other than the original poster
may benefit from it.  When you post to the list, please make sure that
your answer is not a duplication of a previous answer.

Try to summarize the essential part of the question in your reply. Do
not feel obliged to quote the entire original message.

When answers are sent to you individually and not to the mailing list,
it is considered good etiquette to summarize the answers and send the
summary to the mailing list so that others may have the benefit of
responses you received that helped you solve your problem.


File: manual.info,  Node: forums,  Next: irc,  Prev: mailing-lists,  Up: information-sources

1.5.2 MySQL Community Support at the MySQL Forums
-------------------------------------------------

The forums at `http://forums.mysql.com' are an important community
resource. Many forums are available, grouped into these general
categories:

   * Migration

   * MySQL Usage

   * MySQL Connectors

   * Programming Languages

   * Tools

   * 3rd-Party Applications

   * Storage Engines

   * MySQL Technology

   * SQL Standards

   * Business


File: manual.info,  Node: irc,  Next: mysql-enterprise-information,  Prev: forums,  Up: information-sources

1.5.3 MySQL Community Support on Internet Relay Chat (IRC)
----------------------------------------------------------

In addition to the various MySQL mailing lists and forums, you can find
experienced community people on Internet Relay Chat (IRC).  These are
the best networks/channels currently known to us:

*freenode* (see `http://www.freenode.net/' for servers)

   * `#mysql' is primarily for MySQL questions, but other database and
     general SQL questions are welcome.  Questions about PHP, Perl, or
     C in combination with MySQL are also common.

If you are looking for IRC client software to connect to an IRC
network, take a look at `xChat' (`http://www.xchat.org/'). X-Chat (GPL
licensed) is available for Unix as well as for Windows platforms (a free
Windows build of X-Chat is available at
`http://www.silverex.org/download/').


File: manual.info,  Node: mysql-enterprise-information,  Prev: irc,  Up: information-sources

1.5.4 MySQL Enterprise
----------------------

Sun Microsystems, Inc. offers technical support in the form of MySQL
Enterprise. For organizations that rely on the MySQL DBMS for
business-critical production applications, MySQL Enterprise is a
commercial subscription offering which includes:

   * MySQL Enterprise Server

   * MySQL Enterprise Monitor

   * Monthly Rapid Updates and Quarterly Service Packs

   * MySQL Knowledge Base

   * 24x7 Technical and Consultative Support

MySQL Enterprise is available in multiple tiers, giving you the
flexibility to choose the level of service that best matches your
needs. For more information, see MySQL Enterprise
(http://www.mysql.com/products/enterprise/).


File: manual.info,  Node: bug-reports,  Next: compatibility,  Prev: information-sources,  Up: introduction

1.6 How to Report Bugs or Problems
==================================

Before posting a bug report about a problem, please try to verify that
it is a bug and that it has not been reported already:

   * Start by searching the MySQL online manual at
     `http://dev.mysql.com/doc/'. We try to keep the manual up to date
     by updating it frequently with solutions to newly found problems.
     The change history (`http://dev.mysql.com/doc/mysql/en/news.html')
     can be particularly useful since it is quite possible that a newer
     version contains a solution to your problem.

   * If you get a parse error for an SQL statement, please check your
     syntax closely. If you cannot find something wrong with it, it is
     extremely likely that your current version of MySQL Server doesn't
     support the syntax you are using. If you are using the current
     version and the manual doesn't cover the syntax that you are
     using, MySQL Server doesn't support your statement. In this case,
     your options are to implement the syntax yourself or email
     <licensing@mysql.com> and ask for an offer to implement it.

     If the manual covers the syntax you are using, but you have an
     older version of MySQL Server, you should check the MySQL change
     history to see when the syntax was implemented. In this case, you
     have the option of upgrading to a newer version of MySQL Server.

   * For solutions to some common problems, see *Note problems::.

   * Search the bugs database at `http://bugs.mysql.com/' to see
     whether the bug has been reported and fixed.

   * Search the MySQL mailing list archives at
     `http://lists.mysql.com/'. See *Note mailing-lists::.

   * You can also use `http://www.mysql.com/search/' to search all the
     Web pages (including the manual) that are located at the MySQL Web
     site.

If you cannot find an answer in the manual, the bugs database, or the
mailing list archives, check with your local MySQL expert. If you still
cannot find an answer to your question, please use the following
guidelines for reporting the bug.

The normal way to report bugs is to visit `http://bugs.mysql.com/',
which is the address for our bugs database. This database is public and
can be browsed and searched by anyone. If you log in to the system, you
can enter new reports. If you have no Web access, you can generate a
bug report by using the *Note `mysqlbug': mysqlbug. script described at
the end of this section.

Bugs posted in the bugs database at `http://bugs.mysql.com/' that are
corrected for a given release are noted in the change history.

If you have found a sensitive security bug in MySQL, you can send email
to <security@mysql.com>.

To discuss problems with other users, you can use one of the MySQL
mailing lists. *Note mailing-lists::.

Writing a good bug report takes patience, but doing it right the first
time saves time both for us and for yourself. A good bug report,
containing a full test case for the bug, makes it very likely that we
will fix the bug in the next release. This section helps you write your
report correctly so that you do not waste your time doing things that
may not help us much or at all. Please read this section carefully and
make sure that all the information described here is included in your
report.

Preferably, you should test the problem using the latest production or
development version of MySQL Server before posting. Anyone should be
able to repeat the bug by just using `mysql test < script_file' on your
test case or by running the shell or Perl script that you include in
the bug report. Any bug that we are able to repeat has a high chance of
being fixed in the next MySQL release.

It is most helpful when a good description of the problem is included
in the bug report. That is, give a good example of everything you did
that led to the problem and describe, in exact detail, the problem
itself. The best reports are those that include a full example showing
how to reproduce the bug or problem. See MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).

Remember that it is possible for us to respond to a report containing
too much information, but not to one containing too little. People
often omit facts because they think they know the cause of a problem
and assume that some details do not matter. A good principle to follow
is that if you are in doubt about stating something, state it. It is
faster and less troublesome to write a couple more lines in your report
than to wait longer for the answer if we must ask you to provide
information that was missing from the initial report.

The most common errors made in bug reports are (a) not including the
version number of the MySQL distribution that you use, and (b) not
fully describing the platform on which the MySQL server is installed
(including the platform type and version number). These are highly
relevant pieces of information, and in 99 cases out of 100, the bug
report is useless without them. Very often we get questions like, `Why
doesn't this work for me?' Then we find that the feature requested
wasn't implemented in that MySQL version, or that a bug described in a
report has been fixed in newer MySQL versions.  Errors often are
platform-dependent. In such cases, it is next to impossible for us to
fix anything without knowing the operating system and the version
number of the platform.

If you compiled MySQL from source, remember also to provide information
about your compiler if it is related to the problem.  Often people find
bugs in compilers and think the problem is MySQL-related. Most
compilers are under development all the time and become better version
by version. To determine whether your problem depends on your compiler,
we need to know what compiler you used.  Note that every compiling
problem should be regarded as a bug and reported accordingly.

If a program produces an error message, it is very important to include
the message in your report. If we try to search for something from the
archives, it is better that the error message reported exactly matches
the one that the program produces. (Even the lettercase should be
observed.) It is best to copy and paste the entire error message into
your report. You should never try to reproduce the message from memory.

If you have a problem with Connector/ODBC (MyODBC), please try to
generate a trace file and send it with your report. See the MyODBC
section of *Note connectors-apis::.

If your report includes long query output lines from test cases that
you run with the *Note `mysql': mysql. command-line tool, you can make
the output more readable by using the `--vertical' option or the `\G'
statement terminator. The *Note `EXPLAIN SELECT': explain.  example
later in this section demonstrates the use of `\G'.

Please include the following information in your report:

   * The version number of the MySQL distribution you are using (for
     example, MySQL 5.0.19). You can find out which version you are
     running by executing *Note `mysqladmin version': mysqladmin. The
     *Note `mysqladmin': mysqladmin. program can be found in the `bin'
     directory under your MySQL installation directory.

   * The manufacturer and model of the machine on which you experience
     the problem.

   * The operating system name and version. If you work with Windows,
     you can usually get the name and version number by double-clicking
     your My Computer icon and pulling down the `Help/About Windows'
     menu. For most Unix-like operating systems, you can get this
     information by executing the command `uname -a'.

   * Sometimes the amount of memory (real and virtual) is relevant.  If
     in doubt, include these values.

   * If you are using a source distribution of the MySQL software,
     include the name and version number of the compiler that you used.
     If you have a binary distribution, include the distribution name.

   * If the problem occurs during compilation, include the exact error
     messages and also a few lines of context around the offending code
     in the file where the error occurs.

   * If *Note `mysqld': mysqld. died, you should also report the
     statement that crashed *Note `mysqld': mysqld. You can usually get
     this information by running *Note `mysqld': mysqld. with query
     logging enabled, and then looking in the log after *Note `mysqld':
     mysqld. crashes. See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * If a database table is related to the problem, include the output
     from the `SHOW CREATE TABLE DB_NAME.TBL_NAME' statement in the bug
     report. This is a very easy way to get the definition of any table
     in a database. The information helps us create a situation
     matching the one that you have experienced.

   * The SQL mode in effect when the problem occurred can be
     significant, so please report the value of the `sql_mode' system
     variable. For stored procedure, stored function, and trigger
     objects, the relevant `sql_mode' value is the one in effect when
     the object was created. For a stored procedure or function, the
     *Note `SHOW CREATE PROCEDURE': show-create-procedure. or *Note
     `SHOW CREATE FUNCTION': show-create-function. statement shows the
     relevant SQL mode, or you can query `INFORMATION_SCHEMA' for the
     information:

          SELECT ROUTINE_SCHEMA, ROUTINE_NAME, SQL_MODE
          FROM INFORMATION_SCHEMA.ROUTINES;

     For triggers, you can use this statement:

          SELECT EVENT_OBJECT_SCHEMA, EVENT_OBJECT_TABLE, TRIGGER_NAME, SQL_MODE
          FROM INFORMATION_SCHEMA.TRIGGERS;

   * For performance-related bugs or problems with *Note `SELECT':
     select. statements, you should always include the output of
     `EXPLAIN SELECT ...', and at least the number of rows that the
     *Note `SELECT': select. statement produces. You should also
     include the output from `SHOW CREATE TABLE TBL_NAME' for each table
     that is involved. The more information you provide about your
     situation, the more likely it is that someone can help you.

     The following is an example of a very good bug report. The
     statements are run using the *Note `mysql': mysql.  command-line
     tool. Note the use of the `\G' statement terminator for statements
     that would otherwise provide very long output lines that are
     difficult to read.

          mysql> SHOW VARIABLES;
          mysql> SHOW COLUMNS FROM ...\G
                 <OUTPUT FROM SHOW COLUMNS>
          mysql> EXPLAIN SELECT ...\G
                 <OUTPUT FROM EXPLAIN>
          mysql> FLUSH STATUS;
          mysql> SELECT ...;
                 <A SHORT VERSION OF THE OUTPUT FROM SELECT,
                 INCLUDING THE TIME TAKEN TO RUN THE QUERY>
          mysql> SHOW STATUS;
                 <OUTPUT FROM SHOW STATUS>

   * If a bug or problem occurs while running *Note `mysqld': mysqld,
     try to provide an input script that reproduces the anomaly. This
     script should include any necessary source files. The more closely
     the script can reproduce your situation, the better. If you can
     make a reproducible test case, you should upload it to be attached
     to the bug report.

     If you cannot provide a script, you should at least include the
     output from *Note `mysqladmin variables extended-status
     processlist': mysqladmin. in your report to provide some
     information on how your system is performing.

   * If you cannot produce a test case with only a few rows, or if the
     test table is too big to be included in the bug report (more than
     10 rows), you should dump your tables using *Note `mysqldump':
     mysqldump. and create a `README' file that describes your problem.
     Create a compressed archive of your files using `tar' and `gzip' or
     `zip', and use FTP to transfer the archive to
     `ftp://ftp.mysql.com/pub/mysql/upload/'. Then enter the problem
     into our bugs database at `http://bugs.mysql.com/'.

   * If you believe that the MySQL server produces a strange result
     from a statement, include not only the result, but also your
     opinion of what the result should be, and an explanation
     describing the basis for your opinion.

   * When you provide an example of the problem, it is better to use
     the table names, variable names, and so forth that exist in your
     actual situation than to come up with new names. The problem could
     be related to the name of a table or variable. These cases are
     rare, perhaps, but it is better to be safe than sorry. After all,
     it should be easier for you to provide an example that uses your
     actual situation, and it is by all means better for us. If you
     have data that you do not want to be visible to others in the bug
     report, you can use FTP to transfer it to
     `ftp://ftp.mysql.com/pub/mysql/upload/'. If the information is
     really top secret and you do not want to show it even to us, go
     ahead and provide an example using other names, but please regard
     this as the last choice.

   * Include all the options given to the relevant programs, if
     possible. For example, indicate the options that you use when you
     start the *Note `mysqld': mysqld. server, as well as the options
     that you use to run any MySQL client programs. The options to
     programs such as *Note `mysqld': mysqld. and *Note `mysql': mysql,
     and to the `configure' script, are often key to resolving problems
     and are very relevant. It is never a bad idea to include them. If
     your problem involves a program written in a language such as Perl
     or PHP, please include the language processor's version number, as
     well as the version for any modules that the program uses. For
     example, if you have a Perl script that uses the `DBI' and
     `DBD::mysql' modules, include the version numbers for Perl, `DBI',
     and `DBD::mysql'.

   * If your question is related to the privilege system, please
     include the output of *Note `mysqlaccess': mysqlaccess, the output
     of *Note `mysqladmin reload': mysqladmin, and all the error
     messages you get when trying to connect. When you test your
     privileges, you should first run *Note `mysqlaccess': mysqlaccess.
     After this, execute *Note `mysqladmin reload version': mysqladmin.
     and try to connect with the program that gives you trouble.  *Note
     `mysqlaccess': mysqlaccess. can be found in the `bin' directory
     under your MySQL installation directory.

   * If you have a patch for a bug, do include it. But do not assume
     that the patch is all we need, or that we can use it, if you do
     not provide some necessary information such as test cases showing
     the bug that your patch fixes. We might find problems with your
     patch or we might not understand it at all. If so, we cannot use
     it.

     If we cannot verify the exact purpose of the patch, we will not
     use it. Test cases help us here. Show that the patch handles all
     the situations that may occur. If we find a borderline case (even
     a rare one) where the patch will not work, it may be useless.

   * Guesses about what the bug is, why it occurs, or what it depends
     on are usually wrong. Even the MySQL team cannot guess such things
     without first using a debugger to determine the real cause of a
     bug.

   * Indicate in your bug report that you have checked the reference
     manual and mail archive so that others know you have tried to
     solve the problem yourself.

   * If the problem is that your data appears corrupt or you get errors
     when you access a particular table, you should first check your
     tables and then try to repair them with *Note `CHECK TABLE':
     check-table. and *Note `REPAIR TABLE': repair-table. or with *Note
     `myisamchk': myisamchk. See *Note server-administration::.

     If you are running Windows, please verify the value of
     `lower_case_table_names' using the `SHOW VARIABLES LIKE
     'lower_case_table_names'' statement. This variable affects how the
     server handles lettercase of database and table names. Its effect
     for a given value should be as described in *Note
     identifier-case-sensitivity::.

   * If you often get corrupted tables, you should try to find out when
     and why this happens. In this case, the error log in the MySQL
     data directory may contain some information about what happened.
     (This is the file with the `.err' suffix in the name.) See *Note
     error-log::. Please include any relevant information from this
     file in your bug report. Normally *Note `mysqld': mysqld. should
     _never_ crash a table if nothing killed it in the middle of an
     update. If you can find the cause of *Note `mysqld': mysqld.
     dying, it is much easier for us to provide you with a fix for the
     problem. See *Note what-is-crashing::.

   * If possible, download and install the most recent version of MySQL
     Server and check whether it solves your problem. All versions of
     the MySQL software thoroughly tested and should work without
     problems. We believe in making everything as backward-compatible
     as possible, and you should be able to switch MySQL versions
     without difficulty. See *Note which-version::.

If you have no Web access and cannot report a bug by visiting
`http://bugs.mysql.com/', you can use the *Note `mysqlbug': mysqlbug.
script to generate a bug report (or a report about any problem). *Note
`mysqlbug': mysqlbug. helps you generate a report by determining much
of the following information automatically, but if something important
is missing, please include it with your message. *Note `mysqlbug':
mysqlbug. can be found in the `scripts' directory (source distribution)
and in the `bin' directory under your MySQL installation directory
(binary distribution).


File: manual.info,  Node: compatibility,  Next: credits,  Prev: bug-reports,  Up: introduction

1.7 MySQL Standards Compliance
==============================

* Menu:

* standards::                    What Standards MySQL Follows
* sql-mode::                     Selecting SQL Modes
* ansi-mode::                    Running MySQL in ANSI Mode
* extensions-to-ansi::           MySQL Extensions to Standard SQL
* differences-from-ansi::        MySQL Differences from Standard SQL
* constraints::                  How MySQL Deals with Constraints

This section describes how MySQL relates to the ANSI/ISO SQL standards.
MySQL Server has many extensions to the SQL standard, and here you can
find out what they are and how to use them. You can also find
information about functionality missing from MySQL Server, and how to
work around some of the differences.

The SQL standard has been evolving since 1986 and several versions
exist. In this manual, `SQL-92' refers to the standard released in
1992, `SQL:1999' refers to the standard released in 1999, `SQL:2003'
refers to the standard released in 2003, and `SQL:2008' refers to the
most recent version of the standard, released in 2008. We use the
phrase `the SQL standard' or `standard SQL' to mean the current version
of the SQL Standard at any time.

One of our main goals with the product is to continue to work toward
compliance with the SQL standard, but without sacrificing speed or
reliability. We are not afraid to add extensions to SQL or support for
non-SQL features if this greatly increases the usability of MySQL
Server for a large segment of our user base.  The *Note `HANDLER':
handler. interface is an example of this strategy. See *Note handler::.

We continue to support transactional and non-transactional databases to
satisfy both mission-critical 24/7 usage and heavy Web or logging usage.

MySQL Server was originally designed to work with medium-sized
databases (10-100 million rows, or about 100MB per table) on small
computer systems. Today MySQL Server handles terabyte-sized databases,
but the code can also be compiled in a reduced version suitable for
hand-held and embedded devices. The compact design of the MySQL server
makes development in both directions possible without any conflicts in
the source tree.

Currently, we are not targeting real-time support, although MySQL
replication capabilities offer significant functionality.

High-availability database clustering is available using the
`NDBCLUSTER' storage engine. However, the `NDBCLUSTER' storage engine is
currently not supported in MySQL 6.0. Instead, you should use MySQL
Cluster NDB 6.2 or 6.3, which are based on MySQL 5.1 but contain the
latest improvements and fixes for `NDBCLUSTER'. See MySQL Cluster NDB
6.X/7.X (http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html),
for more information.

We are implementing XML functionality beginning in MySQL 5.1, which
supports most of the W3C XPath standard. We plan to increase support
for XML as part of future MySQL development. See *Note xml-functions::.


File: manual.info,  Node: standards,  Next: sql-mode,  Prev: compatibility,  Up: compatibility

1.7.1 What Standards MySQL Follows
----------------------------------

Our aim is to support the full ANSI/ISO SQL standard, but without
making concessions to speed and quality of the code.

ODBC levels 0-3.51.


File: manual.info,  Node: sql-mode,  Next: ansi-mode,  Prev: standards,  Up: compatibility

1.7.2 Selecting SQL Modes
-------------------------

The MySQL server can operate in different SQL modes, and can apply
these modes differentially for different clients. This capability
enables each application to tailor the server's operating mode to its
own requirements.

SQL modes control aspects of server operation such as what SQL syntax
MySQL should support and what kind of data validation checks it should
perform. This makes it easier to use MySQL in different environments
and to use MySQL together with other database servers.

You can set the default SQL mode by starting *Note `mysqld': mysqld.
with the `--sql-mode="MODE_VALUE"' option. You can also change the mode
at runtime by setting the `sql_mode' system variable with a *Note `SET
[GLOBAL|SESSION] sql_mode='MODE_VALUE'': set-option.  statement.

For more information on setting the SQL mode, see *Note
server-sql-mode::.


File: manual.info,  Node: ansi-mode,  Next: extensions-to-ansi,  Prev: sql-mode,  Up: compatibility

1.7.3 Running MySQL in ANSI Mode
--------------------------------

You can tell *Note `mysqld': mysqld. to run in ANSI mode with the
`--ansi' startup option.  Running the server in ANSI mode is the same
as starting it with the following options:

     --transaction-isolation=SERIALIZABLE --sql-mode=ANSI

You can achieve the same effect at runtime by executing these two
statements:

     SET GLOBAL TRANSACTION ISOLATION LEVEL SERIALIZABLE;
     SET GLOBAL sql_mode = 'ANSI';

You can see that setting the `sql_mode' system variable to `'ANSI''
enables all SQL mode options that are relevant for ANSI mode as follows:

     mysql> SET GLOBAL sql_mode='ANSI';
     mysql> SELECT @@global.sql_mode;
             -> 'REAL_AS_FLOAT,PIPES_AS_CONCAT,ANSI_QUOTES,IGNORE_SPACE,ANSI'

Note that running the server in ANSI mode with `--ansi' is not quite
the same as setting the SQL mode to `'ANSI''. The `--ansi' option
affects the SQL mode and also sets the transaction isolation level.
Setting the SQL mode to `'ANSI'' has no effect on the isolation level.

See *Note server-options::, and *Note sql-mode::.


File: manual.info,  Node: extensions-to-ansi,  Next: differences-from-ansi,  Prev: ansi-mode,  Up: compatibility

1.7.4 MySQL Extensions to Standard SQL
--------------------------------------

MySQL Server supports some extensions that you probably won't find in
other SQL DBMSs. Be warned that if you use them, your code won't be
portable to other SQL servers. In some cases, you can write code that
includes MySQL extensions, but is still portable, by using comments of
the following form:

     /*! MYSQL-SPECIFIC CODE */

In this case, MySQL Server parses and executes the code within the
comment as it would any other SQL statement, but other SQL servers will
ignore the extensions. For example, MySQL Server recognizes the
`STRAIGHT_JOIN' keyword in the following statement, but other servers
will not:

     SELECT /*! STRAIGHT_JOIN */ col1 FROM table1,table2 WHERE ...

If you add a version number after the ``!'' character, the syntax within
the comment is executed only if the MySQL version is greater than or
equal to the specified version number. The `TEMPORARY' keyword in the
following comment is executed only by servers from MySQL 3.23.02 or
higher:

     CREATE /*!32302 TEMPORARY */ TABLE t (a INT);

The following descriptions list MySQL extensions, organized by category.

   * Organization of data on disk

     MySQL Server maps each database to a directory under the MySQL
     data directory, and maps tables within a database to file names in
     the database directory. This has a few implications:

        * Database and table names are case sensitive in MySQL Server
          on operating systems that have case-sensitive file names
          (such as most Unix systems). See *Note
          identifier-case-sensitivity::.

        * You can use standard system commands to back up, rename,
          move, delete, and copy tables that are managed by the
          `MyISAM' storage engine. For example, it is possible to
          rename a `MyISAM' table by renaming the `.MYD', `.MYI', and
          `.frm' files to which the table corresponds. (Nevertheless, it
          is preferable to use *Note `RENAME TABLE': rename-table. or
          `ALTER TABLE ...  RENAME' and let the server rename the
          files.)

   * General language syntax

        * By default, strings can be enclosed by either ``"'' or ``''',
          not just by ``'''. (If the `ANSI_QUOTES' SQL mode is enabled,
          strings can be enclosed only by ``''' and the server
          interprets strings enclosed by ``"'' as identifiers.)

        * ``\'' is the escape character in strings.

        * In SQL statements, you can access tables from different
          databases with the DB_NAME.TBL_NAME syntax. Some SQL servers
          provide the same functionality but call this `User space'.
          MySQL Server doesn't support tablespaces such as used in
          statements like this: `CREATE TABLE ralph.my_table ... IN
          my_tablespace'.

   * SQL statement syntax

        * The *Note `ANALYZE TABLE': analyze-table, *Note `CHECK
          TABLE': check-table, *Note `OPTIMIZE TABLE': optimize-table,
          and *Note `REPAIR TABLE': repair-table. statements.

        * The *Note `CREATE DATABASE': create-database, *Note `DROP
          DATABASE': drop-database, and *Note `ALTER DATABASE':
          alter-database.  statements. See *Note create-database::,
          *Note drop-database::, and *Note alter-database::.

        * The *Note `DO': do. statement.

        * *Note `EXPLAIN SELECT': explain. to obtain a description of
          how tables are processed by the query optimizer.

        * The *Note `FLUSH': flush. and *Note `RESET': reset.
          statements.

        * The *Note `SET': set-option.  statement. See *Note
          set-option::.

        * The *Note `SHOW': show. statement. See *Note show::. As of
          MySQL 5.0, the information produced by many of the
          MySQL-specific *Note `SHOW': show. statements can be obtained
          in more standard fashion by using *Note `SELECT': select. to
          query `INFORMATION_SCHEMA'. See *Note information-schema::.

        * Use of *Note `LOAD DATA INFILE': load-data. In many cases,
          this syntax is compatible with Oracle's *Note `LOAD DATA
          INFILE': load-data. See *Note load-data::.

        * Use of *Note `RENAME TABLE': rename-table. See *Note
          rename-table::.

        * Use of *Note `REPLACE': replace. instead of *Note `DELETE':
          delete. plus *Note `INSERT': insert. See *Note replace::.

        * Use of `CHANGE COL_NAME', `DROP COL_NAME', or *Note `DROP
          INDEX': drop-index, `IGNORE' or `RENAME' in *Note `ALTER
          TABLE': alter-table.  statements. Use of multiple `ADD',
          `ALTER', `DROP', or `CHANGE' clauses in an *Note `ALTER
          TABLE': alter-table. statement.  See *Note alter-table::.

        * Use of index names, indexes on a prefix of a column, and use
          of `INDEX' or `KEY' in *Note `CREATE TABLE': create-table.
          statements. See *Note create-table::.

        * Use of `TEMPORARY' or `IF NOT EXISTS' with *Note `CREATE
          TABLE': create-table.

        * Use of `IF EXISTS' with *Note `DROP TABLE': drop-table. and
          *Note `DROP DATABASE': drop-database.

        * The capability of dropping multiple tables with a single
          *Note `DROP TABLE': drop-table. statement.

        * The `ORDER BY' and `LIMIT' clauses of the *Note `UPDATE':
          update. and *Note `DELETE': delete. statements.

        * `INSERT INTO TBL_NAME SET COL_NAME = ...' syntax.

        * The `DELAYED' clause of the *Note `INSERT': insert. and *Note
          `REPLACE': replace. statements.

        * The `LOW_PRIORITY' clause of the *Note `INSERT': insert,
          *Note `REPLACE': replace, *Note `DELETE': delete, and *Note
          `UPDATE': update. statements.

        * Use of `INTO OUTFILE' or `INTO DUMPFILE' in *Note `SELECT':
          select. statements. See *Note select::.

        * Options such as `STRAIGHT_JOIN' or `SQL_SMALL_RESULT' in
          *Note `SELECT': select. statements.

        * You don't need to name all selected columns in the `GROUP BY'
          clause. This gives better performance for some very specific,
          but quite normal queries. See *Note
          group-by-functions-and-modifiers::.

        * You can specify `ASC' and `DESC' with `GROUP BY', not just
          with `ORDER BY'.

        * The ability to set variables in a statement with the `:='
          assignment operator:

               mysql> SELECT @a:=SUM(total),@b:=COUNT(*),@a/@b AS avg
                   -> FROM test_table;
               mysql> SELECT @t1:=(@t2:=1)+@t3:=4,@t1,@t2,@t3;

   * Data types

        * The *Note `MEDIUMINT': numeric-types, *Note `SET': set, and
          *Note `ENUM': enum. data types, and the various *Note `BLOB':
          blob. and *Note `TEXT': blob. data types.

        * The `AUTO_INCREMENT', `BINARY', `NULL', `UNSIGNED', and
          `ZEROFILL' data type attributes.

   * Functions and operators

        * To make it easier for users who migrate from other SQL
          environments, MySQL Server supports aliases for many
          functions. For example, all string functions support both
          standard SQL syntax and ODBC syntax.

        * MySQL Server understands the `||' and `&&' operators to mean
          logical OR and AND, as in the C programming language. In
          MySQL Server, `||' and `OR' are synonyms, as are `&&' and
          `AND'.  Because of this nice syntax, MySQL Server doesn't
          support the standard SQL `||' operator for string
          concatenation; use `CONCAT()' instead. Because `CONCAT()'
          takes any number of arguments, it is easy to convert use of
          the `||' operator to MySQL Server.

        * Use of `COUNT(DISTINCT VALUE_LIST)' where VALUE_LIST has more
          than one element.

        * String comparisons are case-insensitive by default, with sort
          ordering determined by the collation of the current character
          set, which is `latin1' (cp1252 West European) by default. If
          you don't like this, you should declare your columns with the
          `BINARY' attribute or use the `BINARY' cast, which causes
          comparisons to be done using the underlying character code
          values rather then a lexical ordering.

        * The `%' operator is a synonym for `MOD()'. That is, `N % M'
          is equivalent to `MOD(N,M)'.  `%' is supported for C
          programmers and for compatibility with PostgreSQL.

        * The `=', `<>', `<=', `<', `>=', `>', `<<', `>>', `<=>', `AND',
          `OR', or `LIKE' operators may be used in expressions in the
          output column list (to the left of the `FROM') in *Note
          `SELECT': select. statements. For example:

               mysql> SELECT col1=1 AND col2=2 FROM my_table;

        * The `LAST_INSERT_ID()' function returns the most recent
          `AUTO_INCREMENT' value. See *Note information-functions::.

        * `LIKE' is allowed on numeric values.

        * The `REGEXP' and `NOT REGEXP' extended regular expression
          operators.

        * `CONCAT()' or `CHAR()' with one argument or more than two
          arguments. (In MySQL Server, these functions can take a
          variable number of arguments.)

        * The `BIT_COUNT()', `CASE', `ELT()', `FROM_DAYS()', `FORMAT()',
          `IF()', `PASSWORD()', `ENCRYPT()', `MD5()', `ENCODE()',
          `DECODE()', `PERIOD_ADD()', `PERIOD_DIFF()', `TO_DAYS()', and
          `WEEKDAY()' functions.

        * Use of `TRIM()' to trim substrings. Standard SQL supports
          removal of single characters only.

        * The `GROUP BY' functions `STD()', `BIT_OR()', `BIT_AND()',
          `BIT_XOR()', and `GROUP_CONCAT()'. See *Note
          group-by-functions-and-modifiers::.

For a prioritized list indicating when new extensions are added to
MySQL Server, you should consult the online MySQL development roadmap
at `http://dev.mysql.com/doc/mysql/en/roadmap.html'.


File: manual.info,  Node: differences-from-ansi,  Next: constraints,  Prev: extensions-to-ansi,  Up: compatibility

1.7.5 MySQL Differences from Standard SQL
-----------------------------------------

* Menu:

* ansi-diff-select-into-table::  `SELECT INTO TABLE'
* ansi-diff-transactions::       Transactions and Atomic Operations
* ansi-diff-triggers::           Stored Routines and Triggers
* ansi-diff-foreign-keys::       Foreign Keys
* ansi-diff-views::              Views
* ansi-diff-comments::           '`--'' as the Start of a Comment

We try to make MySQL Server follow the ANSI SQL standard and the ODBC
SQL standard, but MySQL Server performs operations differently in some
cases:

   * There are several differences between the MySQL and standard SQL
     privilege systems. For example, in MySQL, privileges for a table
     are not automatically revoked when you delete a table. You must
     explicitly issue a *Note `REVOKE': revoke. statement to revoke
     privileges for a table. For more information, see *Note revoke::.

   * The `CAST()' function does not support cast to *Note `REAL':
     numeric-types. or *Note `BIGINT': numeric-types. See *Note
     cast-functions::.


File: manual.info,  Node: ansi-diff-select-into-table,  Next: ansi-diff-transactions,  Prev: differences-from-ansi,  Up: differences-from-ansi

1.7.5.1 `SELECT INTO TABLE'
...........................

MySQL Server doesn't support the `SELECT ... INTO TABLE' Sybase SQL
extension. Instead, MySQL Server supports the `INSERT INTO ... SELECT'
standard SQL syntax, which is basically the same thing. See *Note
insert-select::. For example:

     INSERT INTO tbl_temp2 (fld_id)
         SELECT tbl_temp1.fld_order_id
         FROM tbl_temp1 WHERE tbl_temp1.fld_order_id > 100;

Alternatively, you can use *Note `SELECT ... INTO OUTFILE': select. or
`CREATE TABLE ...  SELECT'.

As of MySQL 5.0, you can use `SELECT ...  INTO' with user-defined
variables. The same syntax can also be used inside stored routines
using cursors and local variables. See *Note select-into-statement::.


File: manual.info,  Node: ansi-diff-transactions,  Next: ansi-diff-triggers,  Prev: ansi-diff-select-into-table,  Up: differences-from-ansi

1.7.5.2 Transactions and Atomic Operations
..........................................

MySQL Server (version 3.23-max and all versions 4.0 and above) supports
transactions with the `InnoDB' transactional storage engine. `InnoDB'
provides _full_ ACID compliance. See *Note storage-engines::. For
information about `InnoDB' differences from standard SQL with regard to
treatment of transaction errors, see *Note innodb-error-handling::.

The other non-transactional storage engines in MySQL Server (such as
`MyISAM') follow a different paradigm for data integrity called `atomic
operations.' In transactional terms, `MyISAM' tables effectively always
operate in `autocommit = 1' mode. Atomic operations often offer
comparable integrity with higher performance.

Because MySQL Server supports both paradigms, you can decide whether
your applications are best served by the speed of atomic operations or
the use of transactional features. This choice can be made on a
per-table basis.

As noted, the tradeoff for transactional versus non-transactional
storage engines lies mostly in performance.  Transactional tables have
significantly higher memory and disk space requirements, and more CPU
overhead. On the other hand, transactional storage engines such as
`InnoDB' also offer many significant features. MySQL Server's modular
design allows the concurrent use of different storage engines to suit
different requirements and deliver optimum performance in all
situations.

MySQL Enterprise

For expert advice on choosing and tuning storage engines, subscribe to
the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

But how do you use the features of MySQL Server to maintain rigorous
integrity even with the non-transactional `MyISAM' tables, and how do
these features compare with the transactional storage engines?

   * If your applications are written in a way that is dependent on
     being able to call *Note `ROLLBACK': commit.  rather than *Note
     `COMMIT': commit. in critical situations, transactions are more
     convenient.  Transactions also ensure that unfinished updates or
     corrupting activities are not committed to the database; the
     server is given the opportunity to do an automatic rollback and
     your database is saved.

     If you use non-transactional tables, MySQL Server in almost all
     cases allows you to resolve potential problems by including simple
     checks before updates and by running simple scripts that check the
     databases for inconsistencies and automatically repair or warn if
     such an inconsistency occurs. Note that just by using the MySQL
     log or even adding one extra log, you can normally fix tables
     perfectly with no data integrity loss.

   * More often than not, critical transactional updates can be
     rewritten to be atomic. Generally speaking, all integrity problems
     that transactions solve can be done with *Note `LOCK TABLES':
     lock-tables. or atomic updates, ensuring that there are no
     automatic aborts from the server, which is a common problem with
     transactional database systems.

   * To be safe with MySQL Server, regardless of whether you use
     transactional tables, you only need to have backups and have
     binary logging turned on. When that is true, you can recover from
     any situation that you could with any other transactional database
     system. It is always good to have backups, regardless of which
     database system you use.

The transactional paradigm has its advantages and disadvantages. Many
users and application developers depend on the ease with which they can
code around problems where an abort appears to be necessary, or is
necessary. However, even if you are new to the atomic operations
paradigm, or more familiar with transactions, do consider the speed
benefit that non-transactional tables can offer on the order of three to
five times the speed of the fastest and most optimally tuned
transactional tables.

In situations where integrity is of highest importance, MySQL Server
offers transaction-level reliability and integrity even for
non-transactional tables. If you lock tables with *Note `LOCK TABLES':
lock-tables, all updates stall until integrity checks are made. If you
obtain a `READ LOCAL' lock (as opposed to a write lock) for a table
that allows concurrent inserts at the end of the table, reads are
allowed, as are inserts by other clients. The newly inserted records
are not be seen by the client that has the read lock until it releases
the lock. With *Note `INSERT DELAYED': insert-delayed, you can write
inserts that go into a local queue until the locks are released,
without having the client wait for the insert to complete. See *Note
concurrent-inserts::, and *Note insert-delayed::.

`Atomic,' in the sense that we mean it, is nothing magical. It only
means that you can be sure that while each specific update is running,
no other user can interfere with it, and there can never be an
automatic rollback (which can happen with transactional tables if you
are not very careful). MySQL Server also guarantees that there are no
dirty reads.

Following are some techniques for working with non-transactional tables:

   * Loops that need transactions normally can be coded with the help
     of *Note `LOCK TABLES': lock-tables, and you don't need cursors to
     update records on the fly.

   * To avoid using *Note `ROLLBACK': commit, you can employ the
     following strategy:

       1. Use *Note `LOCK TABLES': lock-tables. to lock all the tables
          you want to access.

       2. Test the conditions that must be true before performing the
          update.

       3. Update if the conditions are satisfied.

       4. Use *Note `UNLOCK TABLES': lock-tables. to release your locks.

     This is usually a much faster method than using transactions with
     possible rollbacks, although not always.  The only situation this
     solution doesn't handle is when someone kills the threads in the
     middle of an update. In that case, all locks are released but some
     of the updates may not have been executed.

   * You can also use functions to update records in a single
     operation. You can get a very efficient application by using the
     following techniques:

        * Modify columns relative to their current value.

        * Update only those columns that actually have changed.

     For example, when we are updating customer information, we update
     only the customer data that has changed and test only that none of
     the changed data, or data that depends on the changed data, has
     changed compared to the original row. The test for changed data is
     done with the `WHERE' clause in the *Note `UPDATE': update.
     statement. If the record wasn't updated, we give the client a
     message: `Some of the data you have changed has been changed by
     another user.' Then we show the old row versus the new row in a
     window so that the user can decide which version of the customer
     record to use.

     This gives us something that is similar to column locking but is
     actually even better because we only update some of the columns,
     using values that are relative to their current values. This means
     that typical *Note `UPDATE': update. statements look something
     like these:

          UPDATE tablename SET pay_back=pay_back+125;

          UPDATE customer
            SET
              customer_date='current_date',
              address='new address',
              phone='new phone',
              money_owed_to_us=money_owed_to_us-125
            WHERE
              customer_id=id AND address='old address' AND phone='old phone';

     This is very efficient and works even if another client has
     changed the values in the `pay_back' or `money_owed_to_us' columns.

   * In many cases, users have wanted *Note `LOCK TABLES': lock-tables.
     or *Note `ROLLBACK': commit.  for the purpose of managing unique
     identifiers. This can be handled much more efficiently without
     locking or rolling back by using an `AUTO_INCREMENT' column and
     either the `LAST_INSERT_ID()' SQL function or the *Note
     `mysql_insert_id()': mysql-insert-id. C API function. See *Note
     information-functions::, and *Note mysql-insert-id::.

     You can generally code around the need for row-level locking. Some
     situations really do need it, and `InnoDB' tables support row-level
     locking. Otherwise, with `MyISAM' tables, you can use a flag
     column in the table and do something like the following:

          UPDATE TBL_NAME SET row_flag=1 WHERE id=ID;

     MySQL returns `1' for the number of affected rows if the row was
     found and `row_flag' wasn't `1' in the original row. You can think
     of this as though MySQL Server changed the preceding statement to:

          UPDATE TBL_NAME SET row_flag=1 WHERE id=ID AND row_flag <> 1;


File: manual.info,  Node: ansi-diff-triggers,  Next: ansi-diff-foreign-keys,  Prev: ansi-diff-transactions,  Up: differences-from-ansi

1.7.5.3 Stored Routines and Triggers
....................................

Stored procedures and functions are implemented beginning with MySQL
5.0. See *Note stored-routines::.

Basic trigger functionality is implemented beginning with MySQL 5.0.2,
with further development planned for MySQL 5.1.  See *Note triggers::.


File: manual.info,  Node: ansi-diff-foreign-keys,  Next: ansi-diff-views,  Prev: ansi-diff-triggers,  Up: differences-from-ansi

1.7.5.4 Foreign Keys
....................

In MySQL Server 3.23.44 and up, the `InnoDB' storage engine supports
checking of foreign key constraints, including `CASCADE', `ON DELETE',
and `ON UPDATE'. See *Note innodb-foreign-key-constraints::.

For storage engines other than `InnoDB', MySQL Server parses the
`FOREIGN KEY' syntax in *Note `CREATE TABLE': create-table. statements,
but does not use or store it. In the future, the implementation will be
extended to store this information in the table specification file so
that it may be retrieved by *Note `mysqldump': mysqldump. and ODBC. At
a later stage, foreign key constraints will be implemented for `MyISAM'
tables as well.

Foreign key enforcement offers several benefits to database developers:

   * Assuming proper design of the relationships, foreign key
     constraints make it more difficult for a programmer to introduce
     an inconsistency into the database.

   * Centralized checking of constraints by the database server makes
     it unnecessary to perform these checks on the application side.
     This eliminates the possibility that different applications may
     not all check the constraints in the same way.

   * Using cascading updates and deletes can simplify the application
     code.

   * Properly designed foreign key rules aid in documenting
     relationships between tables.

Do keep in mind that these benefits come at the cost of additional
overhead for the database server to perform the necessary checks.
Additional checking by the server affects performance, which for some
applications may be sufficiently undesirable as to be avoided if
possible. (Some major commercial applications have coded the foreign
key logic at the application level for this reason.)

MySQL gives database developers the choice of which approach to use. If
you don't need foreign keys and want to avoid the overhead associated
with enforcing referential integrity, you can choose another storage
engine instead, such as `MyISAM'. (For example, the `MyISAM' storage
engine offers very fast performance for applications that perform only
*Note `INSERT': insert. and *Note `SELECT': select. operations. In this
case, the table has no holes in the middle and the inserts can be
performed concurrently with retrievals. See *Note concurrent-inserts::.)

If you choose not to take advantage of referential integrity checks,
keep the following considerations in mind:

   * In the absence of server-side foreign key relationship checking,
     the application itself must handle relationship issues. For
     example, it must take care to insert rows into tables in the
     proper order, and to avoid creating orphaned child records. It
     must also be able to recover from errors that occur in the middle
     of multiple-record insert operations.

   * If `ON DELETE' is the only referential integrity capability an
     application needs, you can achieve a similar effect as of MySQL
     Server 4.0 by using multiple-table *Note `DELETE': delete.
     statements to delete rows from many tables with a single
     statement. See *Note delete::.

   * A workaround for the lack of `ON DELETE' is to add the appropriate
     *Note `DELETE': delete. statements to your application when you
     delete records from a table that has a foreign key. In practice,
     this is often as quick as using foreign keys and is more portable.

Be aware that the use of foreign keys can sometimes lead to problems:

   * Foreign key support addresses many referential integrity issues,
     but it is still necessary to design key relationships carefully to
     avoid circular rules or incorrect combinations of cascading
     deletes.

   * It is not uncommon for a DBA to create a topology of relationships
     that makes it difficult to restore individual tables from a
     backup. (MySQL alleviates this difficulty by allowing you to
     temporarily disable foreign key checks when reloading a table that
     depends on other tables. See *Note
     innodb-foreign-key-constraints::. As of MySQL 4.1.1, *Note
     `mysqldump': mysqldump. generates dump files that take advantage
     of this capability automatically when they are reloaded.)

Note that foreign keys in SQL are used to check and enforce referential
integrity, not to join tables. If you want to get results from multiple
tables from a *Note `SELECT': select. statement, you do this by
performing a join between them:

     SELECT * FROM t1 INNER JOIN t2 ON t1.id = t2.id;

See *Note join::, and *Note example-foreign-keys::.

The `FOREIGN KEY' syntax without `ON DELETE ...' is often used by ODBC
applications to produce automatic `WHERE' clauses.


File: manual.info,  Node: ansi-diff-views,  Next: ansi-diff-comments,  Prev: ansi-diff-foreign-keys,  Up: differences-from-ansi

1.7.5.5 Views
.............

Views (including updatable views) are implemented beginning with MySQL
Server 5.0.1. See *Note views::.

Views are useful for allowing users to access a set of relations
(tables) as if it were a single table, and limiting their access to
just that. Views can also be used to restrict access to rows (a subset
of a particular table). For access control to columns, you can also use
the sophisticated privilege system in MySQL Server. See *Note
privilege-system::.

In designing an implementation of views, our ambitious goal, as much as
is possible within the confines of SQL, has been full compliance with
`Codd's Rule #6' for relational database systems: `All views that are
theoretically updatable, should in practice also be updatable.'


File: manual.info,  Node: ansi-diff-comments,  Prev: ansi-diff-views,  Up: differences-from-ansi

1.7.5.6 '`--'' as the Start of a Comment
........................................

Standard SQL uses the C syntax `/* this is a comment */' for comments,
and MySQL Server supports this syntax as well. MySQL also support
extensions to this syntax that allow MySQL-specific SQL to be embedded
in the comment, as described in *Note comments::.

Standard SQL uses ``--'' as a start-comment sequence. MySQL Server uses
``#'' as the start comment character. MySQL Server 3.23.3 and up also
supports a variant of the ``--'' comment style.  That is, the ``--''
start-comment sequence must be followed by a space (or by a control
character such as a newline). The space is required to prevent problems
with automatically generated SQL queries that use constructs such as
the following, where we automatically insert the value of the payment
for `payment':

     UPDATE account SET credit=credit-payment

Consider about what happens if `payment' has a negative value such as
`-1':

     UPDATE account SET credit=credit--1

`credit--1' is a legal expression in SQL, but ``--'' is interpreted as
the start of a comment, part of the expression is discarded. The result
is a statement that has a completely different meaning than intended:

     UPDATE account SET credit=credit

The statement produces no change in value at all. This illustrates that
allowing comments to start with ``--'' can have serious consequences.

Using our implementation requires a space following the ``--'' in order
for it to be recognized as a start-comment sequence in MySQL Server
3.23.3 and newer. Therefore, `credit--1' is safe to use.

Another safe feature is that the *Note `mysql': mysql.  command-line
client ignores lines that start with ``--''.

The following information is relevant only if you are running a MySQL
version earlier than 3.23.3:

If you have an SQL script in a text file that contains ``--'' comments,
you should use the *Note `replace': replace-utility. utility as follows
to convert the comments to use ``#'' characters before executing the
script:

     shell> replace " --" " #" < text-file-with-funny-comments.sql \
              | mysql DB_NAME

That is safer than executing the script in the usual way:

     shell> mysql DB_NAME < text-file-with-funny-comments.sql

You can also edit the script file `in place' to change the ``--''
comments to ``#'' comments:

     shell> replace " --" " #" -- text-file-with-funny-comments.sql

Change them back with this command:

     shell> replace " #" " --" -- text-file-with-funny-comments.sql

See *Note replace-utility::.


File: manual.info,  Node: constraints,  Prev: differences-from-ansi,  Up: compatibility

1.7.6 How MySQL Deals with Constraints
--------------------------------------

* Menu:

* constraint-primary-key::       `PRIMARY KEY' and `UNIQUE' Index Constraints
* constraint-invalid-data::      Constraints on Invalid Data
* constraint-enum::              `ENUM' and `SET' Constraints

MySQL allows you to work both with transactional tables that allow
rollback and with non-transactional tables that do not.  Because of
this, constraint handling is a bit different in MySQL than in other
DBMSs. We must handle the case when you have inserted or updated a lot
of rows in a non-transactional table for which changes cannot be rolled
back when an error occurs.

The basic philosophy is that MySQL Server tries to produce an error for
anything that it can detect while parsing a statement to be executed,
and tries to recover from any errors that occur while executing the
statement. We do this in most cases, but not yet for all.

The options MySQL has when an error occurs are to stop the statement in
the middle or to recover as well as possible from the problem and
continue. By default, the server follows the latter course. This means,
for example, that the server may coerce illegal values to the closest
legal values.

Several SQL mode options are available to provide greater control over
handling of bad data values and whether to continue statement execution
or abort when errors occur. Using these options, you can configure
MySQL Server to act in a more traditional fashion that is like other
DBMSs that reject improper input. The SQL mode can be set globally at
server startup to affect all clients. Individual clients can set the
SQL mode at runtime, which enables each client to select the behavior
most appropriate for its requirements. See *Note server-sql-mode::.

MySQL Enterprise

To be alerted when there is no form of server-enforced data integrity,
subscribe to the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The following sections describe how MySQL Server handles different
types of constraints.


File: manual.info,  Node: constraint-primary-key,  Next: constraint-invalid-data,  Prev: constraints,  Up: constraints

1.7.6.1 `PRIMARY KEY' and `UNIQUE' Index Constraints
....................................................

Normally, errors occurs for data-change statements (such as *Note
`INSERT': insert. or *Note `UPDATE': update.) that would violate
primary-key, unique-key, or foreign-key constraints. If you are using a
transactional storage engine such as `InnoDB', MySQL automatically
rolls back the statement. If you are using a non-transactional storage
engine, MySQL stops processing the statement at the row for which the
error occurred and leaves any remaining rows unprocessed.

MySQL supports an `IGNORE' keyword for *Note `INSERT': insert, *Note
`UPDATE': update, and so forth. If you use it, MySQL ignores
primary-key or unique-key violations and continues processing with the
next row. See the section for the statement that you are using (*Note
insert::, *Note update::, and so forth).

You can get information about the number of rows actually inserted or
updated with the *Note `mysql_info()': mysql-info. C API function.  You
can also use the *Note `SHOW WARNINGS': show-warnings. statement. See
*Note mysql-info::, and *Note show-warnings::.

Currently, only `InnoDB' tables support foreign keys. See *Note
innodb-foreign-key-constraints::. We plan to add foreign key support by
other storage engines in a future MySQL release. See *Note roadmap::.


File: manual.info,  Node: constraint-invalid-data,  Next: constraint-enum,  Prev: constraint-primary-key,  Up: constraints

1.7.6.2 Constraints on Invalid Data
...................................

By default, MySQL is forgiving of illegal or improper data values and
coerces them to legal values for data entry.  However, you can change
the server SQL mode to select more traditional treatment of bad values
such that the server rejects them and aborts the statement in which
they occur. See *Note server-sql-mode::.

This section describes the default (forgiving) behavior of MySQL, as
well as the strict SQL mode and how it differs.

If you are not using strict mode, then whenever you insert an
`incorrect' value into a column, such as a `NULL' into a `NOT NULL'
column or a too-large numeric value into a numeric column, MySQL sets
the column to the `best possible value' instead of producing an error:
The following rules describe in more detail how this works:

   * If you try to store an out of range value into a numeric column,
     MySQL Server instead stores zero, the smallest possible value, or
     the largest possible value, whichever is closest to the invalid
     value.

   * For strings, MySQL stores either the empty string or as much of
     the string as can be stored in the column.

   * If you try to store a string that doesn't start with a number into
     a numeric column, MySQL Server stores 0.

   * Invalid values for *Note `ENUM': enum. and *Note `SET': set.
     columns are handled as described in *Note constraint-enum::.

   * MySQL allows you to store certain incorrect date values into *Note
     `DATE': datetime. and *Note `DATETIME': datetime. columns (such as
     `'2000-02-31'' or `'2000-02-00''). The idea is that it is not the
     job of the SQL server to validate dates. If MySQL can store a date
     value and retrieve exactly the same value, MySQL stores it as
     given. If the date is totally wrong (outside the server's ability
     to store it), the special `zero' date value `'0000-00-00'' is
     stored in the column instead.

   * If you try to store `NULL' into a column that doesn't take `NULL'
     values, an error occurs for single-row *Note `INSERT': insert.
     statements. For multiple-row *Note `INSERT': insert.  statements
     or for `INSERT INTO ...  SELECT' statements, MySQL Server stores
     the implicit default value for the column data type. In general,
     this is `0' for numeric types, the empty string (`''') for string
     types, and the `zero' value for date and time types.  Implicit
     default values are discussed in *Note data-type-defaults::.

   * If an *Note `INSERT': insert. statement specifies no value for a
     column, MySQL inserts its default value if the column definition
     includes an explicit `DEFAULT' clause. If the definition has no
     such `DEFAULT' clause, MySQL inserts the implicit default value
     for the column data type.

The reason for using the preceding rules in non-strict mode is that we
can't check these conditions until the statement has begun executing.
We can't just roll back if we encounter a problem after updating a few
rows, because the storage engine may not support rollback. The option
of terminating the statement is not that good; in this case, the update
would be `half done,' which is probably the worst possible scenario. In
this case, it is better to `do the best you can' and then continue as
if nothing happened.

In MySQL 5.0.2 and up, you can select stricter treatment of input
values by using the `STRICT_TRANS_TABLES' or `STRICT_ALL_TABLES' SQL
modes:

     SET sql_mode = 'STRICT_TRANS_TABLES';
     SET sql_mode = 'STRICT_ALL_TABLES';

`STRICT_TRANS_TABLES' enables strict mode for transactional storage
engines, and also to some extent for non-transactional engines. It
works like this:

   * For transactional storage engines, bad data values occurring
     anywhere in a statement cause the statement to abort and roll back.

   * For non-transactional storage engines, a statement aborts if the
     error occurs in the first row to be inserted or updated. (When the
     error occurs in the first row, the statement can be aborted to
     leave the table unchanged, just as for a transactional table.)
     Errors in rows after the first do not abort the statement, because
     the table has already been changed by the first row. Instead, bad
     data values are adjusted and result in warnings rather than
     errors. In other words, with `STRICT_TRANS_TABLES', a wrong value
     causes MySQL to roll back all updates done so far, if that can be
     done without changing the table. But once the table has been
     changed, further errors result in adjustments and warnings.

For even stricter checking, enable `STRICT_ALL_TABLES'. This is the
same as `STRICT_TRANS_TABLES' except that for non-transactional storage
engines, errors abort the statement even for bad data in rows following
the first row.  This means that if an error occurs partway through a
multiple-row insert or update for a non-transactional table, a partial
update results. Earlier rows are inserted or updated, but those from
the point of the error on are not. To avoid this for non-transactional
tables, either use single-row statements or else use
`STRICT_TRANS_TABLES' if conversion warnings rather than errors are
acceptable. To avoid problems in the first place, do not use MySQL to
check column content. It is safest (and often faster) to let the
application ensure that it passes only legal values to the database.

With either of the strict mode options, you can cause errors to be
treated as warnings by using `INSERT IGNORE' or `UPDATE IGNORE' rather
than *Note `INSERT': insert. or *Note `UPDATE': update. without
`IGNORE'.


File: manual.info,  Node: constraint-enum,  Prev: constraint-invalid-data,  Up: constraints

1.7.6.3 `ENUM' and `SET' Constraints
....................................

*Note `ENUM': enum. and *Note `SET': set. columns provide an efficient
way to define columns that can contain only a given set of values. See
*Note enum::, and *Note set::. However, before MySQL 5.0.2, *Note
`ENUM': enum. and *Note `SET': set. columns do not provide true
constraints on entry of invalid data:

   * *Note `ENUM': enum. columns always have a default value. If you
     specify no default value, then it is `NULL' for columns that can
     have `NULL', otherwise it is the first enumeration value in the
     column definition.

   * If you insert an incorrect value into an *Note `ENUM': enum.
     column or if you force a value into an *Note `ENUM': enum. column
     with `IGNORE', it is set to the reserved enumeration value of `0',
     which is displayed as an empty string in string context.

   * If you insert an incorrect value into a *Note `SET': set. column,
     the incorrect value is ignored. For example, if the column can
     contain the values `'a'', `'b'', and `'c'', an attempt to assign
     `'a,x,b,y'' results in a value of `'a,b''.

As of MySQL 5.0.2, you can configure the server to use strict SQL mode.
See *Note server-sql-mode::. With strict mode enabled, the definition
of a *Note `ENUM': enum. or *Note `SET': set. column does act as a
constraint on values entered into the column. An error occurs for
values that do not satisfy these conditions:

   * An *Note `ENUM': enum. value must be one of those listed in the
     column definition, or the internal numeric equivalent thereof. The
     value cannot be the error value (that is, 0 or the empty string).
     For a column defined as *Note `ENUM('a','b','c')': enum, values
     such as `''', `'d'', or `'ax'' are illegal and are rejected.

   * A *Note `SET': set. value must be the empty string or a value
     consisting only of the values listed in the column definition
     separated by commas. For a column defined as *Note
     `SET('a','b','c')': set, values such as `'d'' or `'a,b,c,d'' are
     illegal and are rejected.

Errors for invalid values can be suppressed in strict mode if you use
`INSERT IGNORE' or `UPDATE IGNORE'. In this case, a warning is
generated rather than an error. For *Note `ENUM': enum, the value is
inserted as the error member (`0').  For *Note `SET': set, the value is
inserted as given except that any invalid substrings are deleted. For
example, `'a,x,b,y'' results in a value of `'a,b''.


File: manual.info,  Node: credits,  Prev: compatibility,  Up: introduction

1.8 Credits
===========

* Menu:

* contributors::                 Contributors to MySQL
* documenters-translators::      Documenters and translators
* used-libraries::               Libraries used by and included with MySQL
* packages::                     Packages that support MySQL
* tools-used-to-create-mysql::   Tools that were used to create MySQL
* supporters::                   Supporters of MySQL

This appendix lists the developers, contributors, and supporters that
have helped to make MySQL what it is today.


File: manual.info,  Node: contributors,  Next: documenters-translators,  Prev: credits,  Up: credits

1.8.1 Contributors to MySQL
---------------------------

Although MySQL AB owns all copyrights in the `MySQL server' and the
`MySQL manual', we wish to recognize those who have made contributions
of one kind or another to the `MySQL distribution'. Contributors are
listed here, in somewhat random order:

   * Gianmassimo Vigazzola <qwerg@mbox.vol.it> or <qwerg@tin.it>

     The initial port to Win32/NT.

   * Per Eric Olsson

     For more or less constructive criticism and real testing of the
     dynamic record format.

   * Irena Pancirov <irena@mail.yacc.it>

     Win32 port with Borland compiler.  `mysqlshutdown.exe' and
     `mysqlwatch.exe'

   * David J. Hughes

     For the effort to make a shareware SQL database. At TcX, the
     predecessor of MySQL AB, we started with `mSQL', but found that it
     couldn't satisfy our purposes so instead we wrote an SQL interface
     to our application builder Unireg. *Note `mysqladmin': mysqladmin.
     and *Note `mysql': mysql. client are programs that were largely
     influenced by their `mSQL' counterparts. We have put a lot of
     effort into making the MySQL syntax a superset of `mSQL'. Many of
     the API's ideas are borrowed from `mSQL' to make it easy to port
     free `mSQL' programs to the MySQL API.  The MySQL software doesn't
     contain any code from `mSQL'. Two files in the distribution
     (`client/insert_test.c' and `client/select_test.c') are based on
     the corresponding (non-copyrighted) files in the `mSQL'
     distribution, but are modified as examples showing the changes
     necessary to convert code from `mSQL' to MySQL Server.  (`mSQL' is
     copyrighted David J. Hughes.)

   * Patrick Lynch

     For helping us acquire `http://www.mysql.com/'.

   * Fred Lindberg

     For setting up qmail to handle the MySQL mailing list and for the
     incredible help we got in managing the MySQL mailing lists.

   * Igor Romanenko <igor@frog.kiev.ua>

     *Note `mysqldump': mysqldump. (previously `msqldump', but ported
     and enhanced by Monty).

   * Yuri Dario

     For keeping up and extending the MySQL OS/2 port.

   * Tim Bunce

     Author of *Note `mysqlhotcopy': mysqlhotcopy.

   * Zarko Mocnik <zarko.mocnik@dem.si>

     Sorting for Slovenian language.

   * "TAMITO" <tommy@valley.ne.jp>

     The `_MB' character set macros and the ujis and sjis character
     sets.

   * Joshua Chamas <joshua@chamas.com>

     Base for concurrent insert, extended date syntax, debugging on NT,
     and answering on the MySQL mailing list.

   * Yves Carlier <Yves.Carlier@rug.ac.be>

     *Note `mysqlaccess': mysqlaccess, a program to show the access
     rights for a user.

   * Rhys Jones <rhys@wales.com> (And GWE Technologies Limited)

     For one of the early JDBC drivers.

   * Dr Xiaokun Kelvin ZHU <X.Zhu@brad.ac.uk>

     Further development of one of the early JDBC drivers and other
     MySQL-related Java tools.

   * James Cooper <pixel@organic.com>

     For setting up a searchable mailing list archive at his site.

   * Rick Mehalick <Rick_Mehalick@i-o.com>

     For `xmysql', a graphical X client for MySQL Server.

   * Doug Sisk <sisk@wix.com>

     For providing RPM packages of MySQL for Red Hat Linux.

   * Diemand Alexander V. <axeld@vial.ethz.ch>

     For providing RPM packages of MySQL for Red Hat Linux-Alpha.

   * Antoni Pamies Olive <toni@readysoft.es>

     For providing RPM versions of a lot of MySQL clients for Intel and
     SPARC.

   * Jay Bloodworth <jay@pathways.sde.state.sc.us>

     For providing RPM versions for MySQL 3.21.

   * David Sacerdote <davids@secnet.com>

     Ideas for secure checking of DNS host names.

   * Wei-Jou Chen <jou@nematic.ieo.nctu.edu.tw>

     Some support for Chinese(BIG5) characters.

   * Wei He <hewei@mail.ied.ac.cn>

     A lot of functionality for the Chinese(GBK) character set.

   * Jan Pazdziora <adelton@fi.muni.cz>

     Czech sorting order.

   * Zeev Suraski <bourbon@netvision.net.il>

     `FROM_UNIXTIME()' time formatting, `ENCRYPT()' functions, and
     `bison' advisor. Active mailing list member.

   * Luuk de Boer <luuk@wxs.nl>

     Ported (and extended) the benchmark suite to `DBI'/`DBD'. Have
     been of great help with `crash-me' and running benchmarks. Some
     new date functions. The *Note `mysql_setpermission':
     mysql-setpermission. script.

   * Alexis Mikhailov <root@medinf.chuvashia.su>

     User-defined functions (UDFs); *Note `CREATE FUNCTION':
     create-function. and *Note `DROP FUNCTION': drop-function.

   * Andreas F. Bobak <bobak@relog.ch>

     The `AGGREGATE' extension to user-defined functions.

   * Ross Wakelin <R.Wakelin@march.co.uk>

     Help to set up InstallShield for MySQL-Win32.

   * Jethro Wright III <jetman@li.net>

     The `libmysql.dll' library.

   * James Pereria <jpereira@iafrica.com>

     Mysqlmanager, a Win32 GUI tool for administering MySQL Servers.

   * Curt Sampson <cjs@portal.ca>

     Porting of MIT-pthreads to NetBSD/Alpha and NetBSD 1.3/i386.

   * Martin Ramsch <m.ramsch@computer.org>

     Examples in the MySQL Tutorial.

   * Steve Harvey

     For making *Note `mysqlaccess': mysqlaccess. more secure.

   * Konark IA-64 Centre of Persistent Systems Private Limited

     `http://www.pspl.co.in/konark/'. Help with the Win64 port of the
     MySQL server.

   * Albert Chin-A-Young.

     Configure updates for Tru64, large file support and better TCP
     wrappers support.

   * John Birrell

     Emulation of `pthread_mutex()' for OS/2.

   * Benjamin Pflugmann

     Extended `MERGE' tables to handle `INSERTS'. Active member on the
     MySQL mailing lists.

   * Jocelyn Fournier

     Excellent spotting and reporting innumerable bugs (especially in
     the MySQL 4.1 subquery code).

   * Marc Liyanage

     Maintaining the Mac OS X packages and providing invaluable
     feedback on how to create Mac OS X PKGs.

   * Robert Rutherford

     Providing invaluable information and feedback about the QNX port.

   * Previous developers of NDB Cluster

     Lots of people were involved in various ways summer students,
     master thesis students, employees. In total more than 100 people
     so too many to mention here. Notable name is Ataullah Dabaghi who
     up until 1999 contributed around a third of the code base. A
     special thanks also to developers of the AXE system which provided
     much of the architectural foundations for NDB Cluster with blocks,
     signals and crash tracing functionality. Also credit should be
     given to those who believed in the ideas enough to allocate of
     their budgets for its development from 1992 to present time.

Other contributors, bugfinders, and testers: James H. Thompson,
Maurizio Menghini, Wojciech Tryc, Luca Berra, Zarko Mocnik, Wim Bonis,
Elmar Haneke, <jehamby@lightside>, <psmith@BayNetworks.com>,
<duane@connect.com.au>, Ted Deppner <ted@psyber.com>, Mike Simons,
Jaakko Hyvatti.

And lots of bug report/patches from the folks on the mailing list.

A big tribute goes to those that help us answer questions on the MySQL
mailing lists:

   * Daniel Koch <dkoch@amcity.com>

     Irix setup.

   * Luuk de Boer <luuk@wxs.nl>

     Benchmark questions.

   * Tim Sailer <tps@users.buoy.com>

     `DBD::mysql' questions.

   * Boyd Lynn Gerber <gerberb@zenez.com>

     SCO-related questions.

   * Richard Mehalick <RM186061@shellus.com>

     `xmysql'-related questions and basic installation questions.

   * Zeev Suraski <bourbon@netvision.net.il>

     Apache module configuration questions (log & auth), PHP-related
     questions, SQL syntax-related questions and other general
     questions.

   * Francesc Guasch <frankie@citel.upc.es>

     General questions.

   * Jonathan J Smith <jsmith@wtp.net>

     Questions pertaining to OS-specifics with Linux, SQL syntax, and
     other things that might need some work.

   * David Sklar <sklar@student.net>

     Using MySQL from PHP and Perl.

   * Alistair MacDonald <A.MacDonald@uel.ac.uk>

     Is flexible and can handle Linux and perhaps HP-UX. Tries to get
     users to use *Note `mysqlbug': mysqlbug.

   * John Lyon <jlyon@imag.net>

     Questions about installing MySQL on Linux systems, using either
     `.rpm' files or compiling from source.

   * Lorvid Ltd. <lorvid@WOLFENET.com>

     Simple billing/license/support/copyright issues.

   * Patrick Sherrill <patrick@coconet.com>

     ODBC and VisualC++ interface questions.

   * Randy Harmon <rjharmon@uptimecomputers.com>

     `DBD', Linux, some SQL syntax questions.


File: manual.info,  Node: documenters-translators,  Next: used-libraries,  Prev: contributors,  Up: credits

1.8.2 Documenters and translators
---------------------------------

The following people have helped us with writing the MySQL
documentation and translating the documentation or error messages in
MySQL.

   * Paul DuBois

     Ongoing help with making this manual correct and understandable.
     That includes rewriting Monty's and David's attempts at English
     into English as other people know it.

   * Kim Aldale

     Helped to rewrite Monty's and David's early attempts at English
     into English.

   * Michael J. Miller Jr.  <mke@terrapin.turbolift.com>

     For the first MySQL manual. And a lot of spelling/language fixes
     for the FAQ (that turned into the MySQL manual a long time ago).

   * Yan Cailin

     First translator of the MySQL Reference Manual into simplified
     Chinese in early 2000 on which the Big5 and HK coded
     (`http://mysql.hitstar.com/') versions were based. Personal home
     page at linuxdb.yeah.net (http://linuxdb.yeah.net).

   * Jay Flaherty <fty@mediapulse.com>

     Big parts of the Perl `DBI'/`DBD' section in the manual.

   * Paul Southworth <pauls@etext.org>, Ray Loyzaga <yar@cs.su.oz.au>

     Proof-reading of the Reference Manual.

   * Therrien Gilbert <gilbert@ican.net>, Jean-Marc Pouyot
     <jmp@scalaire.fr>

     French error messages.

   * Petr Snajdr, <snajdr@pvt.net>

     Czech error messages.

   * Jaroslaw Lewandowski <jotel@itnet.com.pl>

     Polish error messages.

   * Miguel Angel Fernandez Roiz

     Spanish error messages.

   * Roy-Magne Mo <rmo@www.hivolda.no>

     Norwegian error messages and testing of MySQL 3.21.xx.

   * Timur I. Bakeyev <root@timur.tatarstan.ru>

     Russian error messages.

   * <brenno@dewinter.com> & Filippo Grassilli <phil@hyppo.com>

     Italian error messages.

   * Dirk Munzinger <dirk@trinity.saar.de>

     German error messages.

   * Billik Stefan <billik@sun.uniag.sk>

     Slovak error messages.

   * Stefan Saroiu <tzoompy@cs.washington.edu>

     Romanian error messages.

   * Peter Feher

     Hungarian error messages.

   * Roberto M. Serqueira

     Portuguese error messages.

   * Carsten H. Pedersen

     Danish error messages.

   * Arjen Lentz

     Dutch error messages, completing earlier partial translation (also
     work on consistency and spelling).


File: manual.info,  Node: used-libraries,  Next: packages,  Prev: documenters-translators,  Up: credits

1.8.3 Libraries used by and included with MySQL
-----------------------------------------------

The following is a list of the creators of the libraries we have
included with the MySQL server source to make it easy to compile and
install MySQL. We are very thankfully to all individuals that have
created these and it has made our life much easier.

   * Fred Fish

     For his excellent C debugging and trace library. Monty has made a
     number of smaller improvements to the library (speed and
     additional options).

   * Richard A. O'Keefe

     For his public domain string library.

   * Henry Spencer

     For his regex library, used in `WHERE column REGEXP regexp'.

   * Chris Provenzano

     Portable user level pthreads. From the copyright: This product
     includes software developed by Chris Provenzano, the University of
     California, Berkeley, and contributors. We are currently using
     version 1_60_beta6 patched by Monty (see
     `mit-pthreads/Changes-mysql').

   * Jean-loup Gailly and Mark Adler

     For the zlib library (used on MySQL on Windows).

   * Bjorn Benson

     For his safe_malloc (memory checker) package which is used in when
     you build MySQL using one of the `BUILD/compile-*-debug' scripts,
     or manually set the `-DSAFE_MALLOC'.

   * Free Software Foundation

     The `readline' library (used by the *Note `mysql': mysql.
     command-line client).

   * The NetBSD foundation

     The `libedit' package (optionally used by the *Note `mysql':
     mysql. command-line client).

   * www.netlib.org (http://www.netlib.org)

     MySQL incorporates work covered by the following copyright and
     permission notice:

     The author of this software is David M. Gay.

     Copyright (c) 1991, 2000, 2001 by Lucent Technologies.

     Permission to use, copy, modify, and distribute this software for
     any purpose without fee is hereby granted, provided that this
     entire notice is included in all copies of any software which is
     or includes a copy or modification of this software and in all
     copies of the supporting documentation for such software.

     THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
     IMPLIED WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR LUCENT
     MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
     MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
     PURPOSE.


File: manual.info,  Node: packages,  Next: tools-used-to-create-mysql,  Prev: used-libraries,  Up: credits

1.8.4 Packages that support MySQL
---------------------------------

The following is a list of creators/maintainers of some of the most
important API/packages/applications that a lot of people use with MySQL.

We cannot list every possible package here because the list would then
be way to hard to maintain. For other packages, please refer to the
software portal at `http://solutions.mysql.com/software/'.

   * Tim Bunce, Alligator Descartes

     For the `DBD' (Perl) interface.

   * Andreas Koenig <a.koenig@mind.de>

     For the Perl interface for MySQL Server.

   * Jochen Wiedmann <wiedmann@neckar-alb.de>

     For maintaining the Perl `DBD::mysql' module.

   * Eugene Chan <eugene@acenet.com.sg>

     For porting PHP for MySQL Server.

   * Georg Richter

     MySQL 4.1 testing and bug hunting. New PHP 5.0 `mysqli' extension
     (API) for use with MySQL 4.1 and up.

   * Giovanni Maruzzelli <maruzz@matrice.it>

     For porting iODBC (Unix ODBC).

   * Xavier Leroy <Xavier.Leroy@inria.fr>

     The author of LinuxThreads (used by the MySQL Server on Linux).


File: manual.info,  Node: tools-used-to-create-mysql,  Next: supporters,  Prev: packages,  Up: credits

1.8.5 Tools that were used to create MySQL
------------------------------------------

The following is a list of some of the tools we have used to create
MySQL. We use this to express our thanks to those that has created them
as without these we could not have made MySQL what it is today.

   * Free Software Foundation

     From whom we got an excellent compiler (`gcc'), an excellent
     debugger (`gdb' and the `libc' library (from which we have borrowed
     `strto.c' to get some code working in Linux).

   * Free Software Foundation & The XEmacs development team

     For a really great editor/environment used by almost everybody at
     MySQL AB.

   * Julian Seward

     Author of `valgrind', an excellent memory checker tool that has
     helped us find a lot of otherwise hard to find bugs in MySQL.

   * Dorothea Lu"tkehaus and Andreas Zeller

     For `DDD' (The Data Display Debugger) which is an excellent
     graphical front end to `gdb').


File: manual.info,  Node: supporters,  Prev: tools-used-to-create-mysql,  Up: credits

1.8.6 Supporters of MySQL
-------------------------

Although MySQL AB owns all copyrights in the `MySQL server' and the
`MySQL manual', we wish to recognize the following companies, which
helped us finance the development of the `MySQL server', such as by
paying us for developing a new feature or giving us hardware for
development of the `MySQL server'.

   * VA Linux / Andover.net

     Funded replication.

   * NuSphere

     Editing of the MySQL manual.

   * Stork Design studio

     The MySQL Web site in use between 1998-2000.

   * Intel

     Contributed to development on Windows and Linux platforms.

   * Compaq

     Contributed to Development on Linux/Alpha.

   * SWSoft

     Development on the embedded *Note `mysqld': mysqld. version.

   * FutureQuest

     `--skip-show-database'


File: manual.info,  Node: installing,  Next: tutorial,  Prev: introduction,  Up: Top

2 Installing and Upgrading MySQL
********************************

* Menu:

* general-installation-issues::  General Installation Issues
* quick-standard-installation::  Standard MySQL Installation Using a Binary Distribution
* windows-installation::         Installing MySQL on Windows
* linux-rpm::                    Installing MySQL from RPM Packages on Linux
* mac-os-x-installation::        Installing MySQL on Mac OS X
* solaris-installation::         Installing MySQL on Solaris
* netware-installation::         Installing MySQL on NetWare
* installing-binary::            Installing MySQL from `tar.gz' Packages on Other Unix-Like Systems
* installing-source::            MySQL Installation Using a Source Distribution
* post-installation::            Post-Installation Setup and Testing
* upgrade-downgrade::            Upgrading or Downgrading MySQL
* operating-system-specific-notes::  Operating System-Specific Notes
* environment-variables::        Environment Variables
* perl-support::                 Perl Installation Notes

This chapter describes how to obtain and install MySQL. A summary of
the procedure follows and later sections provide the details. If you
plan to upgrade an existing version of MySQL to a newer version rather
than install MySQL for the first time, see *Note upgrade::, for
information about upgrade procedures and about issues that you should
consider before upgrading.

If you are interested in migrating to MySQL from another database
system, you may wish to read *Note faqs-migration::, which contains
answers to some common questions concerning migration issues.

  1. *Determine whether MySQL runs and is supported on your platform.*
     Please note that not all platforms are equally suitable for
     running MySQL, and that not all platforms on which MySQL is known
     to run are officially supported by Sun Microsystems, Inc.:

        * For MySQL Enterprise Server, the officially supported
          platforms are listed at
          `http://www.mysql.com/support/supportedplatforms.html'.

        * MySQL Community Server runs on the platforms listed at *Note
          which-os::.

  2. *Choose which distribution to install.* Several versions of MySQL
     are available, and most are available in several distribution
     formats. You can choose from pre-packaged distributions containing
     binary (precompiled) programs or source code. When in doubt, use a
     binary distribution. We also provide public access to our current
     source tree for those who want to see our most recent developments
     and help us test new code. To determine which version and type of
     distribution you should use, see *Note which-version::.

  3. *Download the distribution that you want to install.* For
     instructions, see *Note getting-mysql::. To verify the integrity
     of the distribution, use the instructions in *Note
     verifying-package-integrity::.

  4. *Install the distribution.* To install MySQL from a binary
     distribution, use the instructions in *Note
     quick-standard-installation::. To install MySQL from a source
     distribution or from the current development source tree, use the
     instructions in *Note installing-source::.

     If you encounter installation difficulties, see *Note
     operating-system-specific-notes::, for information on solving
     problems for particular platforms.

  5. *Perform any necessary post-installation setup.* After installing
     MySQL, read *Note post-installation::. This section contains
     important information about making sure the MySQL server is
     working properly. It also describes how to secure the initial
     MySQL user accounts, _which have no passwords_ until you assign
     passwords. The section applies whether you install MySQL using a
     binary or source distribution.

  6. If you want to run the MySQL benchmark scripts, Perl support for
     MySQL must be available. See *Note perl-support::.


File: manual.info,  Node: general-installation-issues,  Next: quick-standard-installation,  Prev: installing,  Up: installing

2.1 General Installation Issues
===============================

* Menu:

* which-os::                     Operating Systems Supported by MySQL Community Server
* which-version::                Choosing Which MySQL Distribution to Install
* getting-mysql::                How to Get MySQL
* verifying-package-integrity::  Verifying Package Integrity Using MD5 Checksums or `GnuPG'
* installation-layouts::         Installation Layouts

The MySQL installation procedure depends on whether you will install
MySQL Enterprise Server or MySQL Community Server. The set of
applicable platforms depends on which distribution you will install:

   * For MySQL Enterprise Server, the officially supported platforms
     are listed at
     `http://www.mysql.com/support/supportedplatforms.html'.

   * MySQL Community Server runs on the platforms listed at *Note
     which-os::.

For MySQL Enterprise Server, install the main distribution plus any
service packs or hotfixes that you wish to apply using the Enterprise
Installer. For platforms that do not yet have an Enterprise Installer,
use the Community Server instructions.

For MySQL Community Server, install the main distribution plus any
hotfixes and updates:

   * Download a binary release, or download a source release and build
     MySQL yourself from the source code.

   * Retrieve MySQL from the Bazaar tree and build it from source.  The
     Bazaar tree contains the latest developer code.

The immediately following sections contain the information necessary to
choose, download, and verify your distribution. The instructions in
later sections of the chapter describe how to install the distribution
that you choose. For binary distributions, see the instructions at
*Note quick-standard-installation::. To build MySQL from source, use
the instructions at *Note installing-source::.


File: manual.info,  Node: which-os,  Next: which-version,  Prev: general-installation-issues,  Up: general-installation-issues

2.1.1 Operating Systems Supported by MySQL Community Server
-----------------------------------------------------------

This section lists the operating systems on which MySQL Community
Server is known to run.

*Important*:

Sun Microsystems, Inc. does not necessarily provide official support
for all the platforms listed in this section. For information about
those platforms that are officially supported, see MySQL Server
Supported Platforms
(http://www.mysql.com/support/supportedplatforms.html) on the MySQL Web
site.

We use GNU Autoconf, so it is possible to port MySQL to all modern
systems that have a C++ compiler and a working implementation of POSIX
threads. (Thread support is needed for the server. To compile only the
client code, the only requirement is a C++ compiler.)

MySQL has been reported to compile successfully on the following
combinations of operating system and thread package.

   * AIX 4.x, 5.x with native threads. See *Note ibm-aix::.

   * Amiga.

   * FreeBSD 5.x and up with native threads.

   * HP-UX 11.x with the native threads. See *Note hp-ux-11-x::.

   * Linux, builds on all fairly recent Linux distributions with
     `glibc' 2.3. See *Note linux::.

   * Mac OS X. See *Note mac-os-x::.

   * NetBSD 1.3/1.4 Intel and NetBSD 1.3 Alpha. See *Note netbsd::.

   * Novell NetWare 6.0 and 6.5. See *Note netware-installation::.

   * OpenBSD 2.5 and with native threads. OpenBSD earlier than 2.5 with
     the MIT-pthreads package. See *Note openbsd::.

   * SCO OpenServer 5.0.X with a recent port of the FSU Pthreads
     package. See *Note sco::.

   * SCO Openserver 6.0.x. See *Note sco-openserver::.

   * SCO UnixWare 7.1.x. See *Note sco-unixware::.

   * SGI Irix 6.x with native threads. See *Note sgi-irix::.

   * Solaris 2.5 and above with native threads on SPARC and x86.  See
     *Note solaris::.

   * Tru64 Unix. See *Note alpha-dec-unix::.

   * Windows 2000, Windows XP, Windows Vista, Windows Server 2003, and
     Windows Server 2008. See *Note windows-installation::.

MySQL has also been known to run on other systems in the past.  See
*Note operating-system-specific-notes::. Some porting effort might be
required for current versions of MySQL on these systems.

Not all platforms are equally well-suited for running MySQL. How well a
certain platform is suited for a high-load mission-critical MySQL
server is determined by the following factors:

   * General stability of the thread library. A platform may have an
     excellent reputation otherwise, but MySQL is only as stable as the
     thread library it calls, even if everything else is perfect.

   * The capability of the kernel and the thread library to take
     advantage of symmetric multi-processor (SMP) systems. In other
     words, when a process creates a thread, it should be possible for
     that thread to run on a CPU different from the original process.

   * The capability of the kernel and the thread library to run many
     threads that acquire and release a mutex over a short critical
     region frequently without excessive context switches. If the
     implementation of `pthread_mutex_lock()' is too anxious to yield
     CPU time, this hurts MySQL tremendously. If this issue is not
     taken care of, adding extra CPUs actually makes MySQL slower.

   * General file system stability and performance.

   * If your tables are large, performance is affected by the ability
     of the file system to deal with large files at all and to deal
     with them efficiently.

   * Our level of expertise here at Sun Microsystems, Inc. with the
     platform. If we know a platform well, we enable platform-specific
     optimizations and fixes at compile time.  We can also provide
     advice on configuring your system optimally for MySQL.

   * The amount of testing we have done internally for similar
     configurations.

   * The number of users that have run MySQL successfully on the
     platform in similar configurations. If this number is high, the
     likelihood of encountering platform-specific surprises is much
     smaller.


File: manual.info,  Node: which-version,  Next: getting-mysql,  Prev: which-os,  Up: general-installation-issues

2.1.2 Choosing Which MySQL Distribution to Install
--------------------------------------------------

* Menu:

* choosing-version::             Choosing Which Version of MySQL to Install
* choosing-distribution-format::  Choosing a Distribution Format
* many-versions::                How and When Updates Are Released
* mysql-binaries::               MySQL Binaries Compiled by Sun Microsystems, Inc.

When preparing to install MySQL, you should decide which version to
use. MySQL development occurs in several release series, and you can
pick the one that best fits your needs. After deciding which version to
install, you can choose a distribution format.  Releases are available
in binary or source format.


File: manual.info,  Node: choosing-version,  Next: choosing-distribution-format,  Prev: which-version,  Up: which-version

2.1.2.1 Choosing Which Version of MySQL to Install
..................................................

The first decision to make is whether you want to use a production
(stable) release or a development release. In the MySQL development
process, multiple release series co-exist, each at a different stage of
maturity:

   * MySQL 6.0 is the current development release series.

   * MySQL 5.1 is the current General Availability (Production) release
     series. New releases are issued for bugfixes only; no new features
     are being added that could affect stability.

   * MySQL 5.0 is the previous stable (production-quality) release
     series.

   * MySQL 4.1, 4.0, and 3.23 are old stable (production-quality)
     release series. MySQL 4.1 is now at the end of the product
     lifecycle. Active development and support for these versions has
     ended.

     Extended support for MySQL 4.1 remains available.  According to the
     MySQL Lifecycle Policy
     (http://www.mysql.com/company/legal/lifecycle/#policy), only
     Security and Severity Level 1 issues are still being fixed for
     MySQL 4.1.

We do not believe in a complete code freeze because this prevents us
from making bugfixes and other fixes that must be done. By `somewhat
frozen' we mean that we may add small things that should not affect
anything that currently works in a production release. Naturally,
relevant bugfixes from an earlier series propagate to later series.

Normally, if you are beginning to use MySQL for the first time or
trying to port it to some system for which there is no binary
distribution, we recommend going with the General Availability release
series. Currently, this is MySQL 5.1. All MySQL releases, even those
from development series, are checked with the MySQL benchmarks and an
extensive test suite before being issued.

If you are running an older system and want to upgrade, but do not want
to take the chance of having a non-seamless upgrade, you should upgrade
to the latest version in the same release series you are using (where
only the last part of the version number is newer than yours). We have
tried to fix only fatal bugs and make only small, relatively `safe'
changes to that version.

If you want to use new features not present in the production release
series, you can use a version from a development series. Note that
development releases are not as stable as production releases.

If you want to use the very latest sources containing all current
patches and bugfixes, you can use one of our Bazaar repositories. These
are not `releases' as such, but are available as previews of the code
on which future releases are to be based.

The MySQL naming scheme uses release names that consist of three
numbers and a suffix; for example, *mysql-5.0.12-beta*. The numbers
within the release name are interpreted as follows:

   * The first number (*5*) is the major version and describes the file
     format. All MySQL 5 releases have the same file format.

   * The second number (*0*) is the release level. Taken together, the
     major version and release level constitute the release series
     number.

   * The third number (*12*) is the version number within the release
     series. This is incremented for each new release. Usually you want
     the latest version for the series you have chosen.

For each minor update, the last number in the version string is
incremented. When there are major new features or minor
incompatibilities with previous versions, the second number in the
version string is incremented. When the file format changes, the first
number is increased.

Release names also include a suffix to indicates the stability level of
the release. Releases within a series progress through a set of
suffixes to indicate how the stability level improves. The possible
suffixes are:

   * *alpha* indicates that the release is for preview purposes only.
     Known bugs should be documented in the News section (see *Note
     news::). Most alpha releases implement new commands and
     extensions. Active development that may involve major code changes
     can occur in an alpha release.  However, we do conduct testing
     before issuing a release.

   * *beta* indicates that the release is appropriate for use with new
     development.  Within beta releases, the features and compatibility
     should remain consistent. However, beta releases may contain
     numerous and major unaddressed bugs.

     All APIs, externally visible structures, and columns for SQL
     statements will not change during future beta, release candidate,
     or production releases.

   * *rc* indicates a Release Candidate. Release candidates are
     believed to be stable, having passed all of MySQL's internal
     testing, and with all known fatal runtime bugs fixed. However, the
     release has not been in widespread use long enough to know for
     sure that all bugs have been identified. Only minor fixes are
     added. (A release candidate is what formerly was known as a gamma
     release.)

   * If there is no suffix, it indicates that the release is a General
     Availability (GA) or Production release. GA releases are stable,
     having successfully passed through all earlier release stages and
     are believed to be reliable, free of serious bugs, and suitable
     for use in production systems. Only critical bugfixes are applied
     to the release.

MySQL uses a naming scheme that is slightly different from most other
products. In general, it is usually safe to use any version that has
been out for a couple of weeks without being replaced by a new version
within the same release series.

All releases of MySQL are run through our standard tests and benchmarks
to ensure that they are relatively safe to use.  Because the standard
tests are extended over time to check for all previously found bugs,
the test suite keeps getting better.

All releases have been tested at least with these tools:

   * An internal test suite

     The `mysql-test' directory contains an extensive set of test
     cases. We run these tests for every server binary. See *Note
     mysql-test-suite::, for more information about this test suite.

   * The MySQL benchmark suite

     This suite runs a range of common queries. It is also a test to
     determine whether the latest batch of optimizations actually made
     the code faster. See *Note mysql-benchmarks::.

   * The `crash-me' test

     This test tries to determine what features the database supports
     and what its capabilities and limitations are.  See *Note
     mysql-benchmarks::.

We also test the newest MySQL version in our internal production
environment, on at least one machine. We have more than 100GB of data
to work with.


File: manual.info,  Node: choosing-distribution-format,  Next: many-versions,  Prev: choosing-version,  Up: which-version

2.1.2.2 Choosing a Distribution Format
......................................

After choosing which version of MySQL to install, you should decide
whether to use a binary distribution or a source distribution. In most
cases, you should probably use a binary distribution, if one exists for
your platform. Binary distributions are available in native format for
many platforms, such as RPM files for Linux or PKG package installers
for Mac OS X or Solaris. Distributions also are available as Zip
archives or compressed `tar' files.

Reasons to choose a binary distribution include the following:

   * Binary distributions generally are easier to install than source
     distributions.

   * To satisfy different user requirements, we provide several servers
     in binary distributions. *Note `mysqld': mysqld.  is an optimized
     server that is a smaller, faster binary.  *Note `mysqld-debug':
     mysqld. is compiled with debugging support.

     Each of these servers is compiled from the same source
     distribution, though with different configuration options.  All
     native MySQL clients can connect to servers from either MySQL
     version.

Under some circumstances, you may be better off installing MySQL from a
source distribution:

   * You want to install MySQL at some explicit location. The standard
     binary distributions are ready to run at any installation
     location, but you might require even more flexibility to place
     MySQL components where you want.

   * You want to configure *Note `mysqld': mysqld. to ensure that
     features are available that might not be included in the standard
     binary distributions. Here is a list of the most common extra
     options that you may want to use to ensure feature availability:

        * `--with-libwrap'

        * `--with-named-z-libs' (this is done for some of the binaries)

        * `--with-debug[=full]'

   * You want to configure *Note `mysqld': mysqld. without some
     features that are included in the standard binary distributions.
     For example, distributions normally are compiled with support for
     all character sets. If you want a smaller MySQL server, you can
     recompile it with support for only the character sets you need.

   * You have a special compiler (such as `pgcc') or want to use
     compiler options that are better optimized for your processor.
     Binary distributions are compiled with options that should work on
     a variety of processors from the same processor family.

   * You want to use the latest sources from one of the Bazaar
     repositories to have access to all current bugfixes. For example,
     if you have found a bug and reported it to the MySQL development
     team, the bugfix is committed to the source repository and you can
     access it there. The bugfix does not appear in a release until a
     release actually is issued.

   * You want to read (or modify) the C and C++ code that makes up
     MySQL. For this purpose, you should get a source distribution,
     because the source code is always the ultimate manual.

   * Source distributions contain more tests and examples than binary
     distributions.


File: manual.info,  Node: many-versions,  Next: mysql-binaries,  Prev: choosing-distribution-format,  Up: which-version

2.1.2.3 How and When Updates Are Released
.........................................

MySQL is evolving quite rapidly and we want to share new developments
with other MySQL users. We try to produce a new release whenever we
have new and useful features that others also seem to have a need for.

We also try to help users who request features that are easy to
implement. We take note of what our licensed users want, and we
especially take note of what our support customers want and try to help
them in this regard.

No one is _required_ to download a new release. The News section helps
you determine whether the new release has something you really want. See
*Note news::.

We use the following policy when updating MySQL:

   * Enterprise Server releases are meant to appear every 18 months,
     supplemented by quarterly service packs and monthly rapid updates.
     Community Server releases are meant to appear 2-3 times per year.

   * Releases are issued within each series. Enterprise Server releases
     are numbered using even numbers (for example, 6.0.20). Community
     Server releases are numbered using odd numbers (for example,
     6.0.21).

   * Binary distributions for some platforms are made by us for major
     releases. Other people may make binary distributions for other
     systems, but probably less frequently.

   * We make fixes available as soon as we have identified and
     corrected small or non-critical but annoying bugs. The fixes are
     available in source form immediately from our public Bazaar
     repositories, and are included in the next release.

   * If by any chance a security vulnerability or critical bug is found
     in a release, our policy is to fix it in a new release as soon as
     possible. (We would like other companies to do this, too!)


File: manual.info,  Node: mysql-binaries,  Prev: many-versions,  Up: which-version

2.1.2.4 MySQL Binaries Compiled by Sun Microsystems, Inc.
.........................................................

As a service of Sun Microsystems, Inc., we provide a set of binary
distributions of MySQL that are compiled on systems at our site or on
systems where supporters of MySQL kindly have given us access to their
machines.

In addition to the binaries provided in platform-specific package
formats, we offer binary distributions for a number of platforms in the
form of compressed `tar' files (`.tar.gz' files). See *Note
quick-standard-installation::.

The RPM distributions for MySQL 6.0 releases that we make available
through our Web site are generated by MySQL AB.

For Windows distributions, see *Note windows-installation::.

These distributions are generated using the script
`Build-tools/Do-compile', which compiles the source code and creates
the binary `tar.gz' archive using `scripts/make_binary_distribution'.

These binaries are configured and built with the following compilers
and options. This information can also be obtained by looking at the
variables `COMP_ENV_INFO' and `CONFIGURE_LINE' inside the script
`bin/mysqlbug' of every binary `tar' file distribution.

Anyone who has more optimal options for any of the following
`configure' commands can mail them to the MySQL `internals' mailing
list. See *Note mailing-lists::.

If you want to compile a debug version of MySQL, you should add
`--with-debug' or `--with-debug=full' to the following `configure'
commands and remove any `-fomit-frame-pointer' options.

The following binaries are built on our own development systems:

   * Linux 2.4.xx x86 with `gcc' 2.95.3:

          CFLAGS="-O2 -mcpu=pentiumpro" CXX=gcc CXXFLAGS="-O2 -mcpu=pentiumpro
          -felide-constructors" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --enable-assembler --disable-shared
          --with-client-ldflags=-all-static --with-mysqld-ldflags=-all-static

   * Linux 2.4.x x86 with `icc' (Intel C++ Compiler 8.1 or later
     releases):

          CC=icc CXX=icpc CFLAGS="-O3 -unroll2 -ip -mp -no-gcc -restrict"
          CXXFLAGS="-O3 -unroll2 -ip -mp -no-gcc -restrict" ./configure
          --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --enable-assembler
          --disable-shared --with-client-ldflags=-all-static
          --with-mysqld-ldflags=-all-static --with-embedded-server --with-innodb

     Note that versions 8.1 and newer of the Intel compiler have
     separate drivers for 'pure' C (`icc') and C++ (`icpc'); if you use
     `icc' version 8.0 or older for building MySQL, you will need to
     set `CXX=icc'.

   * Linux 2.4.xx Intel Itanium 2 with `ecc' (Intel C++ Itanium
     Compiler 7.0):

          CC=ecc CFLAGS="-O2 -tpp2 -ip -nolib_inline" CXX=ecc CXXFLAGS="-O2
          -tpp2 -ip -nolib_inline" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile

   * Linux 2.4.xx Intel Itanium with `ecc' (Intel C++ Itanium Compiler
     7.0):

          CC=ecc CFLAGS=-tpp1 CXX=ecc CXXFLAGS=-tpp1 ./configure
          --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile

   * Linux 2.4.xx alpha with `ccc' (Compaq C V6.2-505 / Compaq C++
     V6.3-006):

          CC=ccc CFLAGS="-fast -arch generic" CXX=cxx CXXFLAGS="-fast -arch
          generic -noexceptions -nortti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-mysqld-ldflags=-non_shared
          --with-client-ldflags=-non_shared --disable-shared

   * Linux 2.x.xx ppc with `gcc' 2.95.4:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared --with-embedded-server
          --with-innodb

   * Linux 2.4.xx s390 with `gcc' 2.95.3:

          CFLAGS="-O2" CXX=gcc CXXFLAGS="-O2 -felide-constructors" ./configure
          --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --disable-shared
          --with-client-ldflags=-all-static --with-mysqld-ldflags=-all-static

   * Linux 2.4.xx x86_64 (AMD64) with `gcc' 3.2.1:

          CXX=gcc ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared

   * Sun Solaris 8 x86 with `gcc' 3.2.3:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared --with-innodb

   * Sun Solaris 8 SPARC with `gcc' 3.2:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --enable-assembler --with-named-z-libs=no
          --with-named-curses-libs=-lcurses --disable-shared

   * Sun Solaris 8 SPARC 64-bit with `gcc' 3.2:

          CC=gcc CFLAGS="-O3 -m64 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -m64 -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-named-z-libs=no
          --with-named-curses-libs=-lcurses --disable-shared

   * Sun Solaris 9 SPARC with `gcc' 2.95.3:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --enable-assembler --with-named-curses-libs=-lcurses
          --disable-shared

   * Sun Solaris 9 SPARC with `cc-5.0' (Sun Forte 5.0):

          CC=cc-5.0 CXX=CC ASFLAGS="-xarch=v9" CFLAGS="-Xa -xstrconst -mt
          -D_FORTEC_ -xarch=v9" CXXFLAGS="-noex -mt -D_FORTEC_ -xarch=v9"
          ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --enable-assembler
          --with-named-z-libs=no --enable-thread-safe-client --disable-shared

   * IBM AIX 4.3.2 ppc with `gcc' 3.2.3:

          CFLAGS="-O2 -mcpu=powerpc -Wa,-many " CXX=gcc CXXFLAGS="-O2
          -mcpu=powerpc -Wa,-many -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-named-z-libs=no --disable-shared

   * IBM AIX 4.3.3 ppc with `xlC_r' (IBM Visual Age C/C++ 6.0):

          CC=xlc_r CFLAGS="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192"
          CXX=xlC_r CXXFLAGS ="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192"
          ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no
          --disable-shared --with-innodb

   * IBM AIX 5.1.0 ppc with `gcc' 3.3:

          CFLAGS="-O2 -mcpu=powerpc -Wa,-many" CXX=gcc CXXFLAGS="-O2 -mcpu=powerpc
          -Wa,-many -felide-constructors -fno-exceptions -fno-rtti" ./configure
          --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no
          --disable-shared

   * IBM AIX 5.2.0 ppc with `xlC_r' (IBM Visual Age C/C++ 6.0):

          CC=xlc_r CFLAGS="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192"
          CXX=xlC_r CXXFLAGS="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192"
          ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no
          --disable-shared --with-embedded-server --with-innodb

   * HP-UX 10.20 pa-risc1.1 with `gcc' 3.1:

          CFLAGS="-DHPUX -I/opt/dce/include -O3 -fPIC" CXX=gcc CXXFLAGS="-DHPUX
          -I/opt/dce /include -felide-constructors -fno-exceptions -fno-rtti
          -O3 -fPIC" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-pthread --with-named-thread-libs=-ldce
          --with-lib-ccflags=-fPIC --disable-shared

   * HP-UX 11.00 pa-risc with `aCC' (HP ANSI C++ B3910B A.03.50):

          CC=cc CXX=aCC CFLAGS=+DAportable CXXFLAGS=+DAportable ./configure
          --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --disable-shared
          --with-embedded-server --with-innodb

   * HP-UX 11.11 pa-risc2.0 64bit with `aCC' (HP ANSI C++ B3910B
     A.03.33):

          CC=cc CXX=aCC CFLAGS=+DD64 CXXFLAGS=+DD64 ./configure
          --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --disable-shared

   * HP-UX 11.11 pa-risc2.0 32bit with `aCC' (HP ANSI C++ B3910B
     A.03.33):

          CC=cc CXX=aCC CFLAGS="+DAportable" CXXFLAGS="+DAportable" ./configure
          --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --disable-shared
          --with-innodb

   * HP-UX 11.22 ia64 64bit with `aCC' (HP aC++/ANSI C B3910B A.05.50):

          CC=cc CXX=aCC CFLAGS="+DD64 +DSitanium2" CXXFLAGS="+DD64 +DSitanium2"
          ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --disable-shared
          --with-embedded-server --with-innodb

   * Apple Mac OS X 10.2 powerpc with `gcc' 3.1:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared

   * FreeBSD 4.7 i386 with `gcc' 2.95.4:

          CFLAGS=-DHAVE_BROKEN_REALPATH ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --enable-assembler --with-named-z-libs=not-used
          --disable-shared

   * FreeBSD 4.7 i386 using LinuxThreads with `gcc' 2.95.4:

          CFLAGS="-DHAVE_BROKEN_REALPATH -D__USE_UNIX98 -D_REENTRANT
          -D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads"
          CXXFLAGS="-DHAVE_BROKEN_REALPATH -D__USE_UNIX98 -D_REENTRANT
          -D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads" ./configure
          --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --enable-thread-safe-client
          --enable-local-infile --enable-assembler
          --with-named-thread-libs="-DHAVE_GLIBC2_STYLE_GETHOSTBYNAME_R
          -D_THREAD_SAFE -I /usr/local/include/pthread/linuxthreads
          -L/usr/local/lib -llthread -llgcc_r" --disable-shared
          --with-embedded-server --with-innodb

   * QNX Neutrino 6.2.1 i386 with `gcc' 2.95.3qnx-nto 20010315:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared

The following binaries are built on third-party systems kindly provided
to Sun Microsystems, Inc. by other users. These are provided only as a
courtesy; we do not have full control over these systems, so we can
provide only limited support for the binaries built on them.

   * SCO Unix 3.2v5.0.7 i386 with `gcc' 2.95.3:

          CFLAGS="-O3 -mpentium" LDFLAGS=-static CXX=gcc CXXFLAGS="-O3 -mpentium
          -felide-constructors" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-named-z-libs=no --enable-thread-safe-client
          --disable-shared

   * SCO UnixWare 7.1.4 i386 with `CC' 3.2:

          CC=cc CFLAGS="-O" CXX=CC ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-named-z-libs=no --enable-thread-safe-client
          --disable-shared --with-readline

   * SCO OpenServer 6.0.0 i386 with `CC' 3.2:

          CC=cc CFLAGS="-O" CXX=CC ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-named-z-libs=no --enable-thread-safe-client
          --disable-shared --with-readline

   * Compaq Tru64 OSF/1 V5.1 732 alpha with `cc/cxx' (Compaq C
     V6.3-029i / DIGITAL C++ V6.1-027):

          CC="cc -pthread" CFLAGS="-O4 -ansi_alias -ansi_args -fast -inline
          speed -speculate all" CXX="cxx -pthread" CXXFLAGS="-O4 -ansi_alias
          -fast -inline speed -speculate all -noexceptions -nortti" ./configure
          --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile
          --with-named-thread-libs="-lpthread -lmach -lexc -lc" --disable-shared
          --with-mysqld-ldflags=-all-static

   * SGI Irix 6.5 IP32 with `gcc' 3.0.1:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared

   * FreeBSD/sparc64 5.0 with `gcc' 3.2.1:

          CFLAGS=-DHAVE_BROKEN_REALPATH ./configure --prefix=/usr/local/mysql
          --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared --with-innodb

The following compile options have been used for binary packages that
we have provided in the past. These binaries no longer are being
updated, but the compile options are listed here for reference purposes.

   * Linux 2.2.xx SPARC with `egcs' 1.1.2:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --enable-assembler --disable-shared

   * Linux 2.2.x with x686 with `gcc' 2.95.2:

          CFLAGS="-O3 -mpentiumpro" CXX=gcc CXXFLAGS="-O3 -mpentiumpro
          -felide-constructors -fno-exceptions -fno-rtti" ./configure
          --prefix=/usr/local/mysql --enable-assembler
          --with-mysqld-ldflags=-all-static --disable-shared
          --with-extra-charsets=complex

   * SunOS 4.1.4 2 sun4c with `gcc' 2.7.2.1:

          CC=gcc CXX=gcc CXXFLAGS="-O3 -felide-constructors" ./configure
          --prefix=/usr/local/mysql --disable-shared --with-extra-charsets=complex
          --enable-assembler

   * SunOS 5.5.1 (and above) sun4u with `egcs' 1.0.3a or 2.90.27 or
     `gcc' 2.95.2 and newer:

          CC=gcc CFLAGS="-O3" CXX=gcc CXXFLAGS="-O3 -felide-constructors
          -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-low-memory --with-extra-charsets=complex --enable-assembler

   * SunOS 5.6 i86pc with `gcc' 2.8.1:

          CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql
          --with-low-memory --with-extra-charsets=complex

   * BSDI BSD/OS 3.1 i386 with `gcc' 2.7.2.1:

          CC=gcc CXX=gcc CXXFLAGS=-O ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex

   * BSDI BSD/OS 2.1 i386 with `gcc' 2.7.2:

          CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex

   * AIX 4.2 with `gcc' 2.7.2.2:

          CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex


File: manual.info,  Node: getting-mysql,  Next: verifying-package-integrity,  Prev: which-version,  Up: general-installation-issues

2.1.3 How to Get MySQL
----------------------

Check our downloads page at `http://dev.mysql.com/downloads/' for
information about the current version of MySQL and for downloading
instructions. For a complete up-to-date list of MySQL download mirror
sites, see `http://dev.mysql.com/downloads/mirrors.html'. You can also
find information there about becoming a MySQL mirror site and how to
report a bad or out-of-date mirror.

Our main mirror is located at `http://mirrors.sunsite.dk/mysql/'.


File: manual.info,  Node: verifying-package-integrity,  Next: installation-layouts,  Prev: getting-mysql,  Up: general-installation-issues

2.1.4 Verifying Package Integrity Using MD5 Checksums or `GnuPG'
----------------------------------------------------------------

* Menu:

* verifying-md5-checksum::       Verifying the MD5 Checksum
* checking-gpg-signature::       Signature Checking Using `GnuPG'
* checking-rpm-signature::       Signature Checking Using `RPM'

After you have downloaded the MySQL package that suits your needs and
before you attempt to install it, you should make sure that it is
intact and has not been tampered with. There are three means of
integrity checking:

   * MD5 checksums

   * Cryptographic signatures using `GnuPG', the GNU Privacy Guard

   * For RPM packages, the built-in RPM integrity verification mechanism

The following sections describe how to use these methods.

If you notice that the MD5 checksum or GPG signatures do not match,
first try to download the respective package one more time, perhaps
from another mirror site. If you repeatedly cannot successfully verify
the integrity of the package, please notify us about such incidents,
including the full package name and the download site you have been
using, at <webmaster@mysql.com> or <build@mysql.com>. Do not report
downloading problems using the bug-reporting system.


File: manual.info,  Node: verifying-md5-checksum,  Next: checking-gpg-signature,  Prev: verifying-package-integrity,  Up: verifying-package-integrity

2.1.4.1 Verifying the MD5 Checksum
..................................

After you have downloaded a MySQL package, you should make sure that
its MD5 checksum matches the one provided on the MySQL download pages.
Each package has an individual checksum that you can verify with the
following command, where PACKAGE_NAME is the name of the package you
downloaded:

     shell> md5sum PACKAGE_NAME

Example:

     shell> md5sum mysql-standard-6.0.12-linux-i686.tar.gz
     aaab65abbec64d5e907dcd41b8699945  mysql-standard-6.0.12-linux-i686.tar.gz

You should verify that the resulting checksum (the string of
hexadecimal digits) matches the one displayed on the download page
immediately below the respective package.

*Note*:

Make sure to verify the checksum of the _archive file_ (for example,
the `.zip' or `.tar.gz' file) and not of the files that are contained
inside of the archive.

Note that not all operating systems support the `md5sum' command. On
some, it is simply called `md5', and others do not ship it at all. On
Linux, it is part of the *GNU Text Utilities* package, which is
available for a wide range of platforms. You can download the source
code from `http://www.gnu.org/software/textutils/' as well.  If you
have OpenSSL installed, you can use the command `openssl md5
PACKAGE_NAME' instead. A Windows implementation of the `md5' command
line utility is available from `http://www.fourmilab.ch/md5/'.
`winMd5Sum' is a graphical MD5 checking tool that can be obtained from
`http://www.nullriver.com/index/products/winmd5sum'.


File: manual.info,  Node: checking-gpg-signature,  Next: checking-rpm-signature,  Prev: verifying-md5-checksum,  Up: verifying-package-integrity

2.1.4.2 Signature Checking Using `GnuPG'
........................................

Another method of verifying the integrity and authenticity of a package
is to use cryptographic signatures. This is more reliable than using
MD5 checksums, but requires more work.

We sign MySQL downloadable packages with `GnuPG' (GNU Privacy Guard).
`GnuPG' is an Open Source alternative to the well-known Pretty Good
Privacy (`PGP') by Phil Zimmermann. See `http://www.gnupg.org/' for
more information about `GnuPG' and how to obtain and install it on your
system. Most Linux distributions ship with `GnuPG' installed by
default. For more information about `GnuPG', see
`http://www.openpgp.org/'.

To verify the signature for a specific package, you first need to
obtain a copy of our public GPG build key, which you can download from
`http://keyserver.pgp.com/'. The key that you want to obtain is named
`build@mysql.com'. Alternatively, you can cut and paste the key
directly from the following text:

     -----BEGIN PGP PUBLIC KEY BLOCK-----
     Version: GnuPG v1.0.6 (GNU/Linux)
     Comment: For info see http://www.gnupg.org

     mQGiBD4+owwRBAC14GIfUfCyEDSIePvEW3SAFUdJBtoQHH/nJKZyQT7h9bPlUWC3
     RODjQReyCITRrdwyrKUGku2FmeVGwn2u2WmDMNABLnpprWPkBdCk96+OmSLN9brZ
     fw2vOUgCmYv2hW0hyDHuvYlQA/BThQoADgj8AW6/0Lo7V1W9/8VuHP0gQwCgvzV3
     BqOxRznNCRCRxAuAuVztHRcEAJooQK1+iSiunZMYD1WufeXfshc57S/+yeJkegNW
     hxwR9pRWVArNYJdDRT+rf2RUe3vpquKNQU/hnEIUHJRQqYHo8gTxvxXNQc7fJYLV
     K2HtkrPbP72vwsEKMYhhr0eKCbtLGfls9krjJ6sBgACyP/Vb7hiPwxh6rDZ7ITnE
     kYpXBACmWpP8NJTkamEnPCia2ZoOHODANwpUkP43I7jsDmgtobZX9qnrAXw+uNDI
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     =Xquv
     -----END PGP PUBLIC KEY BLOCK-----

To import the build key into your personal public GPG keyring, use `gpg
--import'. For example, if you have saved the key in a file named
`mysql_pubkey.asc', the import command looks like this:

     shell> gpg --import mysql_pubkey.asc
     gpg: key 5072E1F5: public key "MySQL Package signing key (www.mysql.com) <build@mysql.com>" imported
     gpg: Total number processed: 1
     gpg:               imported: 1
     gpg: no ultimately trusted keys found

You can also download the key from the public keyserver using the
public key id, `5072E1F5':

     shell> gpg --recv-keys 5072E1F5
     gpg: requesting key 5072E1F5 from hkp server subkeys.pgp.net
     gpg: key 5072E1F5: "MySQL Package signing key (www.mysql.com) <build@mysql.com>" 2 new signatures
     gpg: no ultimately trusted keys found
     gpg: Total number processed: 1
     gpg:         new signatures: 2

If you want to import the key into your RPM configuration to validate
RPM install packages, you should be able to import the key directly:

     shell> rpm --import mysql_pubkey.asc

If you experience problems, try exporting the key from `gpg' and
importing:

     shell> gpg --export -a 5072e1f5 > 5072e1f5.asc
     shell> rpm --import 5072e1f5.asc

Alternatively, `rpm' also supports loading the key directly from a URL,
and you cas use this manual page:

     shell> rpm --import http://dev.mysql.com/doc/refman/6.0/en/checking-gpg-signature.html

After you have downloaded and imported the public build key, download
your desired MySQL package and the corresponding signature, which also
is available from the download page. The signature file has the same
name as the distribution file with an `.asc' extension, as shown by the
examples in the following table.

Distribution file  `mysql-standard-6.0.12-linux-i686.tar.gz'
Signature file     `mysql-standard-6.0.12-linux-i686.tar.gz.asc'

Make sure that both files are stored in the same directory and then run
the following command to verify the signature for the distribution file:

     shell> gpg --verify PACKAGE_NAME.asc

Example:

     shell> gpg --verify mysql-standard-6.0.12-linux-i686.tar.gz.asc
     gpg: Signature made Tue 12 Jul 2005 23:35:41 EST using DSA key ID 5072E1F5
     gpg: Good signature from "MySQL Package signing key (www.mysql.com) <build@mysql.com>"

The `Good signature' message indicates that everything is all right.
You can ignore any `insecure memory' warning you might obtain.

See the GPG documentation for more information on how to work with
public keys.


File: manual.info,  Node: checking-rpm-signature,  Prev: checking-gpg-signature,  Up: verifying-package-integrity

2.1.4.3 Signature Checking Using `RPM'
......................................

For RPM packages, there is no separate signature. RPM packages have a
built-in GPG signature and MD5 checksum. You can verify a package by
running the following command:

     shell> rpm --checksig PACKAGE_NAME.rpm

Example:

     shell> rpm --checksig MySQL-server-6.0.12-0.glibc23.i386.rpm
     MySQL-server-6.0.12-0.glibc23.i386.rpm: md5 gpg OK

*Note*:

If you are using RPM 4.1 and it complains about `(GPG) NOT OK (MISSING
KEYS: GPG#5072e1f5)', even though you have imported the MySQL public
build key into your own GPG keyring, you need to import the key into
the RPM keyring first. RPM 4.1 no longer uses your personal GPG keyring
(or GPG itself).  Rather, it maintains its own keyring because it is a
system-wide application and a user's GPG public keyring is a
user-specific file. To import the MySQL public key into the RPM
keyring, first obtain the key as described in *Note
checking-gpg-signature::. Then use `rpm --import' to import the key. For
example, if you have saved the public key in a file named
`mysql_pubkey.asc', import it using this command:

     shell> rpm --import mysql_pubkey.asc

If you need to obtain the MySQL public key, see *Note
checking-gpg-signature::.


File: manual.info,  Node: installation-layouts,  Prev: verifying-package-integrity,  Up: general-installation-issues

2.1.5 Installation Layouts
--------------------------

This section describes the default layout of the directories created by
installing binary or source distributions provided by Sun Microsystems,
Inc. A distribution provided by another vendor might use a layout
different from those shown here.

For MySQL 6.0 on Windows, the default installation directory is
`C:\Program Files\MySQL\MySQL Server 6.0'. (Some Windows users prefer to
install in `C:\mysql', the directory that formerly was used as the
default. However, the layout of the subdirectories remains the same.)
The installation directory has the following subdirectories.

*Directory*               *Contents of Directory*
`bin'                     Client programs and the *Note `mysqld':
                          mysqld. server
`data'                    Log files, databases
`Docs'                    Manual in CHM format
`examples'                Example programs and scripts
`include'                 Include (header) files
`lib'                     Libraries
`scripts'                 Utility scripts
`share'                   Error message files

Installations created from our Linux RPM distributions result in files
under the following system directories.

*Directory*               *Contents of Directory*
`/usr/bin'                Client programs and scripts
`/usr/sbin'               The *Note `mysqld': mysqld. server
`/var/lib/mysql'          Log files, databases
`/usr/share/info'         Manual in Info format
`/usr/share/man'          Unix manual pages
`/usr/include/mysql'      Include (header) files
`/usr/lib/mysql'          Libraries
`/usr/share/mysql'        Error message and character set files
`/usr/share/sql-bench'    Benchmarks

On Unix, a `tar' file binary distribution is installed by unpacking it
at the installation location you choose (typically `/usr/local/mysql')
and creates the following directories in that location.

*Directory*               *Contents of Directory*
`bin'                     Client programs and the *Note `mysqld':
                          mysqld. server
`data'                    Log files, databases
`docs'                    Manual in Info format
`man'                     Unix manual pages
`include'                 Include (header) files
`lib'                     Libraries
`scripts'                 *Note `mysql_install_db': mysql-install-db.
`share/mysql'             Error message files
`sql-bench'               Benchmarks

A source distribution is installed after you configure and compile it.
By default, the installation step installs files under `/usr/local', in
the following subdirectories.

*Directory*               *Contents of Directory*
`bin'                     Client programs and scripts
`include/mysql'           Include (header) files
`Docs'                    Manual in Info, CHM formats
`man'                     Unix manual pages
`lib/mysql'               Libraries
`libexec'                 The *Note `mysqld': mysqld. server
`share/mysql'             Error message files
`sql-bench'               Benchmarks and `crash-me' test
`var'                     Databases and log files

Within its installation directory, the layout of a source installation
differs from that of a binary installation in the following ways:

   * The *Note `mysqld': mysqld. server is installed in the `libexec'
     directory rather than in the `bin' directory.

   * The data directory is `var' rather than `data'.

   * *Note `mysql_install_db': mysql-install-db. is installed in the
     `bin' directory rather than in the `scripts' directory.

   * The header file and library directories are `include/mysql' and
     `lib/mysql' rather than `include' and `lib'.

You can create your own binary installation from a compiled source
distribution by executing the `scripts/make_binary_distribution' script
from the top directory of the source distribution.


File: manual.info,  Node: quick-standard-installation,  Next: windows-installation,  Prev: general-installation-issues,  Up: installing

2.2 Standard MySQL Installation Using a Binary Distribution
===========================================================

The next several sections cover the installation of MySQL on platforms
where we offer packages using the native packaging format of the
respective platform. (This is also known as performing a `binary
install.') However, binary distributions of MySQL are available for
many other platforms as well. See *Note installing-binary::, for generic
installation instructions for these packages that apply to all
platforms.

See *Note general-installation-issues::, for more information on what
other binary distributions are available and how to obtain them.


File: manual.info,  Node: windows-installation,  Next: linux-rpm,  Prev: quick-standard-installation,  Up: installing

2.3 Installing MySQL on Windows
===============================

* Menu:

* windows-choosing-package::     Choosing An Installation Package
* windows-using-installer::      Installing MySQL with the Automated Installer
* windows-install-wizard::       Using the MySQL Installation Wizard
* mysql-config-wizard::          MySQL Server Instance Configuration Wizard
* windows-install-archive::      Installing MySQL from a Noinstall Zip Archive
* windows-extract-archive::      Extracting the Install Archive
* windows-create-option-file::   Creating an Option File
* windows-select-server::        Selecting a MySQL Server Type
* windows-server-first-start::   Starting the Server for the First Time
* windows-start-command-line::   Starting MySQL from the Windows Command Line
* windows-start-service::        Starting MySQL as a Windows Service
* windows-testing::              Testing The MySQL Installation
* windows-troubleshooting::      Troubleshooting a MySQL Installation Under Windows
* windows-upgrading::            Upgrading MySQL on Windows
* windows-vs-unix::              MySQL on Windows Compared to MySQL on Unix

A native Windows distribution of MySQL has been available since version
3.21 and represents a sizable percentage of the daily downloads of
MySQL. This section describes the process for installing MySQL on
Windows.

*Note*:

If you are upgrading MySQL from an existing installation older than
MySQL 4.1.5, you must first perform the procedure described in *Note
windows-upgrading::.

To run MySQL on Windows, you need the following:

   * A 32-bit Windows operating system such as Windows 2000, Windows
     XP, Windows Vista, Windows Server 2003, or Windows Server 2008.

     A Windows operating system permits you to run the MySQL server as
     a service. See *Note windows-start-service::.

     Generally, you should install MySQL on Windows using an account
     that has administrator rights. Otherwise, you may encounter
     problems with certain operations such as editing the `PATH'
     environment variable or accessing the `Service Control Manager'.
     Once installed, MySQL does not need to be executed using a user
     with Administrator privileges.

   * TCP/IP protocol support.

   * Enough space on the hard drive to unpack, install, and create the
     databases in accordance with your requirements (generally a
     minimum of 200 megabytes is recommended.)

For a list of limitations within the Windows version of MySQL, see
*Note limits-windows::.

There may also be other requirements, depending on how you plan to use
MySQL:

   * If you plan to connect to the MySQL server via ODBC, you need a
     Connector/ODBC driver. See *Note connector-odbc::.

   * If you plan to use MySQL server with ADO.NET applications, you
     need the Connector/NET driver. See *Note connector-net::.

   * If you need tables with a size larger than 4GB, install MySQL on
     an NTFS or newer file system. Don't forget to use `MAX_ROWS' and
     `AVG_ROW_LENGTH' when you create tables. See *Note create-table::.

MySQL for Windows is available in several distribution formats:

   * Binary distributions are available that contain a setup program
     that installs everything you need so that you can start the server
     immediately. Another binary distribution format contains an
     archive that you simply unpack in the installation location and
     then configure yourself. For details, see *Note
     windows-choosing-package::.

   * The source distribution contains all the code and support files
     for building the executables using the Visual Studio compiler
     system.

Generally speaking, you should use a binary distribution that includes
an installer. It is simpler to use than the others, and you need no
additional tools to get MySQL up and running. The installer for the
Windows version of MySQL, combined with a GUI Configuration Wizard,
automatically installs MySQL, creates an option file, starts the
server, and secures the default user accounts.

*Caution*:

Using virus scanning software such as Norton/Symantec Anti-Virus on
directories containing MySQL data and temporary tables can cause
issues, both in terms of the performance of MySQL and the
virus-scanning software mis-identifying the contents of the files as
containing spam. This is because of the fingerprinting mechanism used
by the virus scanning software, and the way in which MySQL rapidly
updates different files, which may be identified as a potential
security risk.

After installing MySQL Server, it is recommended that you disable virus
scanning on the main directory (`datadir') being used to store your
MySQL table data. There is usually a system built into the virus
scanning software to allow certain directories to be specifically
ignored during virus scanning.

In addition, by default, MySQL creates temporary files in the standard
Windows temporary directory. To prevent the temporary files also being
scanned, you should configure a separate temporary directory for MySQL
temporary files and add this to the virus scanning exclusion list. To
do this, add a configuration option for the `tmpdir' parameter to your
`my.ini' configuration file. For more information, see *Note
windows-create-option-file::.

The following section describes how to install MySQL on Windows using a
binary distribution. To use an installation package that does not
include an installer, follow the procedure described in *Note
windows-install-archive::. To install using a source distribution, see
*Note windows-source-build::.

MySQL distributions for Windows can be downloaded from
`http://dev.mysql.com/downloads/'. See *Note getting-mysql::.


File: manual.info,  Node: windows-choosing-package,  Next: windows-using-installer,  Prev: windows-installation,  Up: windows-installation

2.3.1 Choosing An Installation Package
--------------------------------------

For MySQL 6.0, there are three installation packages to choose from
when installing MySQL on Windows:

   * *The Essentials Package*: This package has a file name similar to
     `mysql-essential-6.0.12-win32.msi' and contains the minimum set of
     files needed to install MySQL on Windows, including the
     Configuration Wizard. This package does not include optional
     components such as the embedded server and benchmark suite.

   * *The Complete Package*: This package has a file name similar to
     `mysql-6.0.12-win32.zip' and contains all files needed for a
     complete Windows installation, including the Configuration Wizard.
     This package includes optional components such as the embedded
     server and benchmark suite.

   * *The Noinstall Archive*: This package has a file name similar to
     `mysql-noinstall-6.0.12-win32.zip' and contains all the files
     found in the Complete install package, with the exception of the
     Configuration Wizard.  This package does not include an automated
     installer, and must be manually installed and configured.

The Essentials package is recommended for most users. It is provided as
an `.msi' file for use with the Windows Installer. The Complete and
Noinstall distributions are packaged as Zip archives. To use them, you
must have a tool that can unpack `.zip' files.

Your choice of install package affects the installation process you
must follow. If you choose to install either the Essentials or Complete
install packages, see *Note windows-using-installer::. If you choose to
install MySQL from the Noinstall archive, see *Note
windows-install-archive::.


File: manual.info,  Node: windows-using-installer,  Next: windows-install-wizard,  Prev: windows-choosing-package,  Up: windows-installation

2.3.2 Installing MySQL with the Automated Installer
---------------------------------------------------

New MySQL users can use the MySQL Installation Wizard and MySQL
Configuration Wizard to install MySQL on Windows. These are designed to
install and configure MySQL in such a way that new users can
immediately get started using MySQL.

The MySQL Installation Wizard and MySQL Configuration Wizard are
available in the Essentials and Complete install packages. They are
recommended for most standard MySQL installations.  Exceptions include
users who need to install multiple instances of MySQL on a single
server host and advanced users who want complete control of server
configuration.


File: manual.info,  Node: windows-install-wizard,  Next: mysql-config-wizard,  Prev: windows-using-installer,  Up: windows-installation

2.3.3 Using the MySQL Installation Wizard
-----------------------------------------

* Menu:

* mysql-install-wizard-starting::  Downloading and Starting the MySQL Installation Wizard
* mysql-install-wizard-install-type::  Choosing an Install Type
* mysql-install-wizard-custom-install::  The Custom Install Dialog
* mysql-install-wizard-confirmation-dialog::  The Confirmation Dialog
* mysql-install-wizard-changes::  Changes Made by MySQL Installation Wizard
* mysql-install-wizard-upgrading::  Upgrading MySQL with the Installation Wizard

MySQL Installation Wizard is an installer for the MySQL server that
uses the latest installer technologies for Microsoft Windows. The MySQL
Installation Wizard, in combination with the MySQL Configuration
Wizard, allows a user to install and configure a MySQL server that is
ready for use immediately after installation.

The MySQL Installation Wizard is the standard installer for all MySQL
server distributions, version 4.1.5 and higher. Users of previous
versions of MySQL need to shut down and remove their existing MySQL
installations manually before installing MySQL with the MySQL
Installation Wizard. See *Note mysql-install-wizard-upgrading::, for
more information on upgrading from a previous version.

Microsoft has included an improved version of their Microsoft Windows
Installer (MSI) in the recent versions of Windows. MSI has become the
de-facto standard for application installations on Windows 2000,
Windows XP, and Windows Server 2003. The MySQL Installation Wizard
makes use of this technology to provide a smoother and more flexible
installation process.

The Microsoft Windows Installer Engine was updated with the release of
Windows XP; those using a previous version of Windows can reference
this Microsoft Knowledge Base article
(http://support.microsoft.com/default.aspx?scid=kb;EN-US;292539) for
information on upgrading to the latest version of the Windows Installer
Engine.

In addition, Microsoft has introduced the WiX (Windows Installer XML)
toolkit recently. This is the first highly acknowledged Open Source
project from Microsoft. We have switched to WiX because it is an Open
Source project and it allows us to handle the complete Windows
installation process in a flexible manner using scripts.

Improving the MySQL Installation Wizard depends on the support and
feedback of users like you. If you find that the MySQL Installation
Wizard is lacking some feature important to you, or if you discover a
bug, please report it in our bugs database using the instructions given
in *Note bug-reports::.


File: manual.info,  Node: mysql-install-wizard-starting,  Next: mysql-install-wizard-install-type,  Prev: windows-install-wizard,  Up: windows-install-wizard

2.3.3.1 Downloading and Starting the MySQL Installation Wizard
..............................................................

The MySQL installation packages can be downloaded from
`http://dev.mysql.com/downloads/'. If the package you download is
contained within a Zip archive, you need to extract the archive first.

*Note*:

If you are installing on Windows Vista it is best to open a network
port before beginning the installation. To do this, first ensure that
you are logged in as an Administrator, go to the `Control Panel', and
double click the `Windows Firewall' icon. Choose the `Allow a program
through Windows Firewall' option and click the `Add port' button.
Enter `MySQL' into the `Name' text box and `3306' (or the port of your
choice) into the `Port number' text box. Also ensure that the `TCP'
protocol radio button is selected. If you wish, you can also limit
access to the MySQL server by choosing the `Change scope' button.
Confirm your choices by clicking the `OK' button. If you do not open a
port prior to installation, you cannot configure the MySQL server
immediately after installation. Additionally, when running the MySQL
Installation Wizard on Windows Vista, ensure that you are logged in as
a user with administrative rights.

The process for starting the wizard depends on the contents of the
installation package you download. If there is a `setup.exe' file
present, double-click it to start the installation process. If there is
an `.msi' file present, double-click it to start the installation
process.

Starting with MySQL 6.0.6, on starting the MySQL Installation Wizard
you will be asked whether you want to run the MySQL Configuration
Wizard once installation has completed and whether you want to register
your installation with MySQL. If you decide to send the registration
information, a small file will be uploaded to the SunConnect service. A
browser window will also open and ask you to sign in to your Sun
Developer Network account or to register for a new account. Your MySQL
registration information will be appended to your Sun Developer Network
account, and you can use the inventory management system to keep track
of the pacakges you have registered. Only information about your
server, version and environment is sent to the SunConnect system.

If an internet connection is not available, then the information will
be stored in two files within the base directory of your MySQL
installation. The files are called `register' and `svctag'.  You can
run then run the registration once an internet connection is available
by running the `SunInventory Registration' link from the server
installation folder within the `Start' menu.


File: manual.info,  Node: mysql-install-wizard-install-type,  Next: mysql-install-wizard-custom-install,  Prev: mysql-install-wizard-starting,  Up: windows-install-wizard

2.3.3.2 Choosing an Install Type
................................

There are three installation types available: *Typical*, *Complete*, and
*Custom*.

The *Typical* installation type installs the MySQL server, the *Note
`mysql': mysql.  command-line client, and the command-line utilities.
The command-line clients and utilities include *Note `mysqldump':
mysqldump, *Note `myisamchk': myisamchk, and several other tools to
help you manage the MySQL server.

The *Complete* installation type installs all components included in
the installation package. The full installation package includes
components such as the embedded server library, the benchmark suite,
support scripts, and documentation.

The *Custom* installation type gives you complete control over which
packages you wish to install and the installation path that is used. See
*Note mysql-install-wizard-custom-install::, for more information on
performing a custom install.

If you choose the *Typical* or *Complete* installation types and click
the `Next' button, you advance to the confirmation screen to verify
your choices and begin the installation. If you choose the *Custom*
installation type and click the `Next' button, you advance to the
custom installation dialog, described in *Note
mysql-install-wizard-custom-install::.


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2.3.3.3 The Custom Install Dialog
.................................

If you wish to change the installation path or the specific components
that are installed by the MySQL Installation Wizard, choose the *Custom*
installation type.

A tree view on the left side of the custom install dialog lists all
available components. Components that are not installed have a red `X'
icon; components that are installed have a gray icon. To change whether
a component is installed, click on that component's icon and choose a
new option from the drop-down list that appears.

You can change the default installation path by clicking the
`Change...' button to the right of the displayed installation path.

After choosing your installation components and installation path,
click the `Next' button to advance to the confirmation dialog.


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2.3.3.4 The Confirmation Dialog
...............................

Once you choose an installation type and optionally choose your
installation components, you advance to the confirmation dialog. Your
installation type and installation path are displayed for you to review.

To install MySQL if you are satisfied with your settings, click the
`Install' button. To change your settings, click the `Back' button.  To
exit the MySQL Installation Wizard without installing MySQL, click the
`Cancel' button.

After installation is complete, you have the option of registering with
the MySQL web site. Registration gives you access to post in the MySQL
forums at forums.mysql.com (http://forums.mysql.com), along with the
ability to report bugs at bugs.mysql.com (http://bugs.mysql.com) and to
subscribe to our newsletter. The final screen of the installer provides
a summary of the installation and gives you the option to launch the
MySQL Configuration Wizard, which you can use to create a configuration
file, install the MySQL service, and configure security settings.


File: manual.info,  Node: mysql-install-wizard-changes,  Next: mysql-install-wizard-upgrading,  Prev: mysql-install-wizard-confirmation-dialog,  Up: windows-install-wizard

2.3.3.5 Changes Made by MySQL Installation Wizard
.................................................

Once you click the `Install' button, the MySQL Installation Wizard
begins the installation process and makes certain changes to your
system which are described in the sections that follow.

*Changes to the Registry*

The MySQL Installation Wizard creates one Windows registry key in a
typical install situation, located in
`HKEY_LOCAL_MACHINE\SOFTWARE\MySQL AB'.

The MySQL Installation Wizard creates a key named after the major
version of the server that is being installed, such as `MySQL Server
6.0'. It contains two string values, `Location' and `Version'. The
`Location' string contains the path to the installation directory. In a
default installation it contains `C:\Program Files\MySQL\MySQL Server
6.0\'. The `Version' string contains the release number.  For example,
for an installation of MySQL Server 6.0.12, the key contains a value of
`6.0.12'.

These registry keys are used to help external tools identify the
installed location of the MySQL server, preventing a complete scan of
the hard-disk to determine the installation path of the MySQL server.
The registry keys are not required to run the server, and if you
install MySQL using the `noinstall' Zip archive, the registry keys are
not created.

*Changes to the Start Menu*

The MySQL Installation Wizard creates a new entry in the Windows
`Start' menu under a common MySQL menu heading named after the major
version of MySQL that you have installed. For example, if you install
MySQL 6.0, the MySQL Installation Wizard creates a `MySQL Server 6.0'
section in the `Start' menu.

The following entries are created within the new `Start' menu section:

   * `MySQL Command Line Client': This is a shortcut to the *Note
     `mysql': mysql. command-line client and is configured to connect
     as the `root' user. The shortcut prompts for a `root' user
     password when you connect.

   * `MySQL Server Instance Config Wizard': This is a shortcut to the
     MySQL Configuration Wizard. Use this shortcut to configure a newly
     installed server, or to reconfigure an existing server.

   * `MySQL Documentation': This is a link to the MySQL server
     documentation that is stored locally in the MySQL server
     installation directory. This option is not available when the
     MySQL server is installed using the Essentials installation
     package.

*Changes to the File System*

The MySQL Installation Wizard by default installs the MySQL 6.0 server
to `C:\PROGRAM FILES\MySQL\MySQL Server 6.0', where PROGRAM FILES is
the default location for applications in your system, and 6.0 is the
major version of your MySQL server. This is the recommended location
for the MySQL server, replacing the former default location `C:\mysql'.

By default, all MySQL applications are stored in a common directory at
`C:\PROGRAM FILES\MySQL', where PROGRAM FILES is the default location
for applications in your Windows installation. A typical MySQL
installation on a developer machine might look like this:

     C:\Program Files\MySQL\MySQL Server 6.0
     C:\Program Files\MySQL\MySQL Administrator 1.0
     C:\Program Files\MySQL\MySQL Query Browser 1.0

This approach makes it easier to manage and maintain all MySQL
applications installed on a particular system.

In MySQL 5.1.23 and earlier, the default location for the data files
used by MySQL is located within the corresponding MySQL Server
installation directory. For MySQL 5.1.24 and later, the default
location of the data directory is the `AppData' directory configured
for the user that installed the MySQL application.


File: manual.info,  Node: mysql-install-wizard-upgrading,  Prev: mysql-install-wizard-changes,  Up: windows-install-wizard

2.3.3.6 Upgrading MySQL with the Installation Wizard
....................................................

The MySQL Installation Wizard can perform server upgrades automatically
using the upgrade capabilities of MSI. That means you do not need to
remove a previous installation manually before installing a new
release. The installer automatically shuts down and removes the
previous MySQL service before installing the new version.

Automatic upgrades are available only when upgrading between
installations that have the same major and minor version numbers. For
example, you can upgrade automatically from MySQL 4.1.5 to MySQL 4.1.6,
but not from MySQL 5.1 to MySQL 6.0.

See *Note windows-upgrading::.


File: manual.info,  Node: mysql-config-wizard,  Next: windows-install-archive,  Prev: windows-install-wizard,  Up: windows-installation

2.3.4 MySQL Server Instance Configuration Wizard
------------------------------------------------

* Menu:

* mysql-config-wizard-starting::  Starting the MySQL Server Instance Configuration Wizard
* mysql-config-wizard-maintenance::  Choosing a Maintenance Option
* mysql-config-wizard-configuration-type::  Choosing a Configuration Type
* mysql-config-wizard-server-type::  The Server Type Dialog
* mysql-config-wizard-database-usage::  The Database Usage Dialog
* mysql-config-wizard-tablespace::  The InnoDB Tablespace Dialog
* mysql-config-wizard-connections::  The Concurrent Connections Dialog
* mysql-config-wizard-networking::  The Networking and Strict Mode Options Dialog
* mysql-config-wizard-character-set::  The Character Set Dialog
* mysql-config-wizard-service::  The Service Options Dialog
* mysql-config-wizard-security::  The Security Options Dialog
* mysql-config-wizard-confirmation::  The Confirmation Dialog

The MySQL Server Instance Configuration Wizard helps automate the
process of configuring your server. It creates a custom MySQL
configuration file (`my.ini' or `my.cnf') by asking you a series of
questions and then applying your responses to a template to generate the
configuration file that is tuned to your installation.

The MySQL Server Instance Configuration Wizard is included with the
MySQL 6.0 server. The MySQL Server Instance Configuration Wizard is
only available for Windows.


File: manual.info,  Node: mysql-config-wizard-starting,  Next: mysql-config-wizard-maintenance,  Prev: mysql-config-wizard,  Up: mysql-config-wizard

2.3.4.1 Starting the MySQL Server Instance Configuration Wizard
...............................................................

The MySQL Server Instance Configuration Wizard is normally started as
part of the installation process. You should only need to run the MySQL
Server Instance Configuration Wizard again when you need to change the
configuration parameters of your server.

If you chose not to open a port prior to installing MySQL on Windows
Vista, you can choose to use the MySQL Server Configuration Wizard
after installation. However, you must open a port in the Windows
Firewall. To do this see the instructions given in *Note
mysql-install-wizard-starting::. Rather than opening a port, you also
have the option of adding MySQL as a program that bypasses the Windows
Firewall. One or the other option is sufficient -- you need not do both.
Additionally, when running the MySQL Server Configuration Wizard on
Windows Vista ensure that you are logged in as a user with
administrative rights.

MySQL Server Instance Configuration Wizard

You can launch the MySQL Configuration Wizard by clicking the `MySQL
Server Instance Config Wizard' entry in the `MySQL' section of the
Windows `Start' menu.

Alternatively, you can navigate to the `bin' directory of your MySQL
installation and launch the `MySQLInstanceConfig.exe' file directly.

The MySQL Server Instance Configuration Wizard places the `my.ini' file
in the installation directory for the MySQL server. This helps
associate configuration files with particular server instances.

To ensure that the MySQL server knows where to look for the `my.ini'
file, an argument similar to this is passed to the MySQL server as part
of the service installation:

     --defaults-file="C:\PROGRAM FILES\MYSQL\MYSQL SERVER 6.0\my.ini"

Here, C:\PROGRAM FILES\MYSQL\MYSQL SERVER 6.0 is replaced with the
installation path to the MySQL Server. The `--defaults-file' option
instructs the MySQL server to read the specified file for configuration
options when it starts.

Apart from making changes to the `my.ini' file by running the MySQL
Server Instance Configuration Wizard again, you can modify it by
opening it with a text editor and making any necessary changes. You can
also modify the server configuration with the MySQL Administrator
(http://www.mysql.com/products/administrator/) utility. For more
information about server configuration, see *Note server-options::.

MySQL clients and utilities such as the *Note `mysql': mysql. and *Note
`mysqldump': mysqldump.  command-line clients are not able to locate the
`my.ini' file located in the server installation directory. To
configure the client and utility applications, create a new `my.ini'
file in the Windows installation directory (for example, `C:\WINDOWS').

Under Windows Server 2003, Windows Server 2000 and Windows XP, MySQL
Server Instance Configuration Wizard will configure MySQL to work as a
Windows service. To start and stop MySQL you use the `Services'
application that is supplied as part of the Windows Administrator Tools.


File: manual.info,  Node: mysql-config-wizard-maintenance,  Next: mysql-config-wizard-configuration-type,  Prev: mysql-config-wizard-starting,  Up: mysql-config-wizard

2.3.4.2 Choosing a Maintenance Option
.....................................

If the MySQL Server Instance Configuration Wizard detects an existing
configuration file, you have the option of either reconfiguring your
existing server, or removing the server instance by deleting the
configuration file and stopping and removing the MySQL service.

To reconfigure an existing server, choose the `Re-configure Instance'
option and click the `Next' button. Any existing configuration file is
not overwritten, but renamed (within the same directory) using a
timestamp (Windows) or sequential number (Linux). To remove the
existing server instance, choose the `Remove Instance' option and click
the `Next' button.

If you choose the `Remove Instance' option, you advance to a
confirmation window. Click the `Execute' button. The MySQL Server
Configuration Wizard stops and removes the MySQL service, and then
deletes the configuration file. The server installation and its `data'
folder are not removed.

If you choose the `Re-configure Instance' option, you advance to the
`Configuration Type' dialog where you can choose the type of
installation that you wish to configure.


File: manual.info,  Node: mysql-config-wizard-configuration-type,  Next: mysql-config-wizard-server-type,  Prev: mysql-config-wizard-maintenance,  Up: mysql-config-wizard

2.3.4.3 Choosing a Configuration Type
.....................................

When you start the MySQL Server Instance Configuration Wizard for a new
MySQL installation, or choose the `Re-configure Instance' option for an
existing installation, you advance to the `Configuration Type' dialog.

MySQL Server Instance Configuration Wizard: Configuration Type

There are two configuration types available: `Detailed Configuration'
and `Standard Configuration'. The `Standard Configuration' option is
intended for new users who want to get started with MySQL quickly
without having to make many decisions about server configuration. The
`Detailed Configuration' option is intended for advanced users who want
more fine-grained control over server configuration.

If you are new to MySQL and need a server configured as a single-user
developer machine, the `Standard Configuration' should suit your needs.
Choosing the `Standard Configuration' option causes the MySQL
Configuration Wizard to set all configuration options automatically
with the exception of `Service Options' and `Security Options'.

The `Standard Configuration' sets options that may be incompatible with
systems where there are existing MySQL installations. If you have an
existing MySQL installation on your system in addition to the
installation you wish to configure, the `Detailed Configuration' option
is recommended.

To complete the `Standard Configuration', please refer to the sections
on `Service Options' and `Security Options' in *Note
mysql-config-wizard-service::, and *Note
mysql-config-wizard-security::, respectively.


File: manual.info,  Node: mysql-config-wizard-server-type,  Next: mysql-config-wizard-database-usage,  Prev: mysql-config-wizard-configuration-type,  Up: mysql-config-wizard

2.3.4.4 The Server Type Dialog
..............................

There are three different server types available to choose from. The
server type that you choose affects the decisions that the MySQL Server
Instance Configuration Wizard makes with regard to memory, disk, and
processor usage.

MySQL Server Instance Configuration Wizard: Server Type

   * `Developer Machine': Choose this option for a typical desktop
     workstation where MySQL is intended only for personal use. It is
     assumed that many other desktop applications are running. The
     MySQL server is configured to use minimal system resources.

   * `Server Machine': Choose this option for a server machine where
     the MySQL server is running alongside other server applications
     such as FTP, email, and Web servers. The MySQL server is
     configured to use a moderate portion of the system resources.

   * `Dedicated MySQL Server Machine': Choose this option for a server
     machine that is intended to run only the MySQL server. It is
     assumed that no other applications are running. The MySQL server
     is configured to use all available system resources.

*Note*:

By selecting one of the preconfigured configurations, the values and
settings of various options in your `my.cnf' or `my.ini' will be
altered accordingly. The default values and options as described in the
reference manual may therefore be different to the options and values
that were created during the execution of the configuration wizard.


File: manual.info,  Node: mysql-config-wizard-database-usage,  Next: mysql-config-wizard-tablespace,  Prev: mysql-config-wizard-server-type,  Up: mysql-config-wizard

2.3.4.5 The Database Usage Dialog
.................................

The `Database Usage' dialog allows you to indicate the storage engines
that you expect to use when creating MySQL tables. The option you
choose determines whether the `InnoDB' storage engine is available and
what percentage of the server resources are available to `InnoDB'.

MySQL Server Instance Configuration Wizard: Usage Dialog

   * `Multifunctional Database': This option enables both the `InnoDB'
     and `MyISAM' storage engines and divides resources evenly between
     the two. This option is recommended for users who use both storage
     engines on a regular basis.

   * `Transactional Database Only': This option enables both the
     `InnoDB' and `MyISAM' storage engines, but dedicates most server
     resources to the `InnoDB' storage engine. This option is
     recommended for users who use `InnoDB' almost exclusively and make
     only minimal use of `MyISAM'.

   * `Non-Transactional Database Only': This option disables the
     `InnoDB' storage engine completely and dedicates all server
     resources to the `MyISAM' storage engine. This option is
     recommended for users who do not use `InnoDB'.

The Configuration Wizard uses a template to generate the server
configuration file. The `Database Usage' dialog sets one of the
following option strings:

     Multifunctional Database:        MIXED
     Transactional Database Only:     INNODB
     Non-Transactional Database Only: MYISAM

When these options are processed through the default template
(my-template.ini) the result is:

     Multifunctional Database:
     default-storage-engine=InnoDB
     _myisam_pct=50

     Transactional Database Only:
     default-storage-engine=InnoDB
     _myisam_pct=5

     Non-Transactional Database Only:
     default-storage-engine=MyISAM
     _myisam_pct=100
     skip-innodb

The `_myisam_pct' value is used to calculate the percentage of
resources dedicated to `MyISAM'. The remaining resources are allocated
to `InnoDB'.


File: manual.info,  Node: mysql-config-wizard-tablespace,  Next: mysql-config-wizard-connections,  Prev: mysql-config-wizard-database-usage,  Up: mysql-config-wizard

2.3.4.6 The InnoDB Tablespace Dialog
....................................

Some users may want to locate the `InnoDB' tablespace files in a
different location than the MySQL server data directory. Placing the
tablespace files in a separate location can be desirable if your system
has a higher capacity or higher performance storage device available,
such as a RAID storage system.

MySQL Server Instance Configuration Wizard: InnoDB Data Tablespace

To change the default location for the `InnoDB' tablespace files,
choose a new drive from the drop-down list of drive letters and choose
a new path from the drop-down list of paths. To create a custom path,
click the `...' button.

If you are modifying the configuration of an existing server, you must
click the `Modify' button before you change the path. In this situation
you must move the existing tablespace files to the new location
manually before starting the server.


File: manual.info,  Node: mysql-config-wizard-connections,  Next: mysql-config-wizard-networking,  Prev: mysql-config-wizard-tablespace,  Up: mysql-config-wizard

2.3.4.7 The Concurrent Connections Dialog
.........................................

To prevent the server from running out of resources, it is important to
limit the number of concurrent connections to the MySQL server that can
be established. The `Concurrent Connections' dialog allows you to
choose the expected usage of your server, and sets the limit for
concurrent connections accordingly. It is also possible to set the
concurrent connection limit manually.

MySQL Server Instance Configuration Wizard: Connections

   * `Decision Support (DSS)/OLAP': Choose this option if your server
     does not require a large number of concurrent connections. The
     maximum number of connections is set at 100, with an average of 20
     concurrent connections assumed.

   * `Online Transaction Processing (OLTP)': Choose this option if your
     server requires a large number of concurrent connections. The
     maximum number of connections is set at 500.

   * `Manual Setting': Choose this option to set the maximum number of
     concurrent connections to the server manually. Choose the number
     of concurrent connections from the drop-down box provided, or
     enter the maximum number of connections into the drop-down box if
     the number you desire is not listed.


File: manual.info,  Node: mysql-config-wizard-networking,  Next: mysql-config-wizard-character-set,  Prev: mysql-config-wizard-connections,  Up: mysql-config-wizard

2.3.4.8 The Networking and Strict Mode Options Dialog
.....................................................

Use the `Networking Options' dialog to enable or disable TCP/IP
networking and to configure the port number that is used to connect to
the MySQL server.

MySQL Server Instance Configuration Wizard: Network Configuration

TCP/IP networking is enabled by default. To disable TCP/IP networking,
uncheck the box next to the `Enable TCP/IP Networking' option.

Port 3306 is used by default. To change the port used to access MySQL,
choose a new port number from the drop-down box or type a new port
number directly into the drop-down box. If the port number you choose
is in use, you are prompted to confirm your choice of port number.

Set the `Server SQL Mode' to either enable or disable strict mode.
Enabling strict mode (default) makes MySQL behave more like other
database management systems.  _If you run applications that rely on
MySQL's old `forgiving' behavior, make sure to either adapt those
applications or to disable strict mode._ For more information about
strict mode, see *Note server-sql-mode::.


File: manual.info,  Node: mysql-config-wizard-character-set,  Next: mysql-config-wizard-service,  Prev: mysql-config-wizard-networking,  Up: mysql-config-wizard

2.3.4.9 The Character Set Dialog
................................

The MySQL server supports multiple character sets and it is possible to
set a default server character set that is applied to all tables,
columns, and databases unless overridden. Use the `Character Set'
dialog to change the default character set of the MySQL server.

MySQL Server Instance Configuration Wizard: Character Set

   * `Standard Character Set': Choose this option if you want to use
     `latin1' as the default server character set.  `latin1' is used
     for English and many Western European languages.

   * `Best Support For Multilingualism': Choose this option if you want
     to use `utf8' as the default server character set. This is a
     Unicode character set that can store characters from many
     different languages.

   * `Manual Selected Default Character Set / Collation': Choose this
     option if you want to pick the server's default character set
     manually. Choose the desired character set from the provided
     drop-down list.


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2.3.4.10 The Service Options Dialog
...................................

On Windows platforms, the MySQL server can be installed as a Windows
service. When installed this way, the MySQL server can be started
automatically during system startup, and even restarted automatically
by Windows in the event of a service failure.

The MySQL Server Instance Configuration Wizard installs the MySQL
server as a service by default, using the service name `MySQL'. If you
do not wish to install the service, uncheck the box next to the
`Install As Windows Service' option. You can change the service name by
picking a new service name from the drop-down box provided or by
entering a new service name into the drop-down box.

*Note*:

Service names can include any legal character except forward (`/') or
backward (`\') slashes, and must be less than 256 characters long.

*Warning*:

If you are installing multiple versions of MySQL onto the same machine,
you _must_ choose a different service name for each version that you
install. If you do not choose a different service for each installed
version then the service manager information will be inconsistent and
this will cause problems when you try to uninstall a previous version.

If you have already installed multiple versions using the same service
name, you must manually edit the contents of the
`HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services' parameters
within the Windows registry to update the association of the service
name with the correct server version.

Typically, when installing multiple versions you create a service name
based on the version information. For example, you might install MySQL
6.x as `mysql6', or specific versions such as MySQL 6.0.8 as
`mysql6008'.

To install the MySQL server as a service but not have it started
automatically at startup, uncheck the box next to the `Launch the MySQL
Server Automatically' option.


File: manual.info,  Node: mysql-config-wizard-security,  Next: mysql-config-wizard-confirmation,  Prev: mysql-config-wizard-service,  Up: mysql-config-wizard

2.3.4.11 The Security Options Dialog
....................................

_It is strongly recommended that you set a `root' password for your
MySQL server_, and the MySQL Server Instance Configuration Wizard
requires by default that you do so. If you do not wish to set a `root'
password, uncheck the box next to the `Modify Security Settings' option.

MySQL Server Instance Configuration Wizard: Security

To set the `root' password, enter the desired password into both the
`New root password' and `Confirm' boxes. If you are reconfiguring an
existing server, you need to enter the existing `root' password into
the `Current root password' box.

To prevent `root' logins from across the network, check the box next to
the `Root may only connect from localhost' option. This increases the
security of your `root' account.

To create an anonymous user account, check the box next to the `Create
An Anonymous Account' option.  Creating an anonymous account can
decrease server security and cause login and permission difficulties.
For this reason, it is not recommended.


File: manual.info,  Node: mysql-config-wizard-confirmation,  Prev: mysql-config-wizard-security,  Up: mysql-config-wizard

2.3.4.12 The Confirmation Dialog
................................

The final dialog in the MySQL Server Instance Configuration Wizard is
the `Confirmation Dialog'. To start the configuration process, click the
`Execute' button. To return to a previous dialog, click the `Back'
button. To exit the MySQL Server Instance Configuration Wizard without
configuring the server, click the `Cancel' button.

MySQL Server Instance Configuration Wizard: Confirmation

After you click the `Execute' button, the MySQL Server Instance
Configuration Wizard performs a series of tasks and displays the
progress onscreen as the tasks are performed.

The MySQL Server Instance Configuration Wizard first determines
configuration file options based on your choices using a template
prepared by MySQL developers and engineers.  This template is named
`my-template.ini' and is located in your server installation directory.

The MySQL Configuration Wizard then writes these options to the
corresponding configuration file.

If you chose to create a service for the MySQL server, the MySQL Server
Instance Configuration Wizard creates and starts the service. If you
are reconfiguring an existing service, the MySQL Server Instance
Configuration Wizard restarts the service to apply your configuration
changes.

If you chose to set a `root' password, the MySQL Configuration Wizard
connects to the server, sets your new `root' password, and applies any
other security settings you may have selected.

After the MySQL Server Instance Configuration Wizard has completed its
tasks, it displays a summary. Click the `Finish' button to exit the
MySQL Server Configuration Wizard.


File: manual.info,  Node: windows-install-archive,  Next: windows-extract-archive,  Prev: mysql-config-wizard,  Up: windows-installation

2.3.5 Installing MySQL from a Noinstall Zip Archive
---------------------------------------------------

Users who are installing from the Noinstall package can use the
instructions in this section to manually install MySQL. The process for
installing MySQL from a Zip archive is as follows:

  1. Extract the archive to the desired install directory

  2. Create an option file

  3. Choose a MySQL server type

  4. Start the MySQL server

  5. Secure the default user accounts

This process is described in the sections that follow.


File: manual.info,  Node: windows-extract-archive,  Next: windows-create-option-file,  Prev: windows-install-archive,  Up: windows-installation

2.3.6 Extracting the Install Archive
------------------------------------

To install MySQL manually, do the following:

  1. If you are upgrading from a previous version please refer to *Note
     windows-upgrading::, before beginning the upgrade process.

  2. Make sure that you are logged in as a user with administrator
     privileges.

  3. Choose an installation location. Traditionally, the MySQL server
     is installed in `C:\mysql'. The MySQL Installation Wizard installs
     MySQL under `C:\Program Files\MySQL'. If you do not install MySQL
     at `C:\mysql', you must specify the path to the install directory
     during startup or in an option file. See *Note
     windows-create-option-file::.

  4. Extract the install archive to the chosen installation location
     using your preferred Zip archive tool. Some tools may extract the
     archive to a folder within your chosen installation location. If
     this occurs, you can move the contents of the subfolder into the
     chosen installation location.


File: manual.info,  Node: windows-create-option-file,  Next: windows-select-server,  Prev: windows-extract-archive,  Up: windows-installation

2.3.7 Creating an Option File
-----------------------------

If you need to specify startup options when you run the server, you can
indicate them on the command line or place them in an option file. For
options that are used every time the server starts, you may find it
most convenient to use an option file to specify your MySQL
configuration. This is particularly true under the following
circumstances:

   * The installation or data directory locations are different from
     the default locations (`C:\Program Files\MySQL\MySQL Server 6.0'
     and `C:\Program Files\MySQL\MySQL Server 6.0\data').

   * You need to tune the server settings, such as memory, cache, or
     InnoDB configuration information.

When the MySQL server starts on Windows, it looks for options in two
files: the `my.ini' file in the Windows directory, and the `C:\my.cnf'
file. The Windows directory typically is named something like
`C:\WINDOWS'. You can determine its exact location from the value of
the `WINDIR' environment variable using the following command:

     C:\> echo %WINDIR%

MySQL looks for options first in the `my.ini' file, and then in the
`my.cnf' file. However, to avoid confusion, it is best if you use only
one file. If your PC uses a boot loader where `C:' is not the boot
drive, your only option is to use the `my.ini' file. Whichever option
file you use, it must be a plain text file.

You can also make use of the example option files included with your
MySQL distribution; see *Note option-files-preconfigured::.

An option file can be created and modified with any text editor, such
as Notepad. For example, if MySQL is installed in `E:\mysql' and the
data directory is in `E:\mydata\data', you can create an option file
containing a `[mysqld]' section to specify values for the `basedir' and
`datadir' options:

     [mysqld]
     # set basedir to your installation path
     basedir=E:/mysql
     # set datadir to the location of your data directory
     datadir=E:/mydata/data

Note that Windows path names are specified in option files using
(forward) slashes rather than backslashes. If you do use backslashes,
you must double them:

     [mysqld]
     # set basedir to your installation path
     basedir=E:\\mysql
     # set datadir to the location of your data directory
     datadir=E:\\mydata\\data

MySQL Enterprise

For expert advice on the start-up options appropriate to your
circumstances, subscribe to the MySQL Enterprise Monitor. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

In MySQL 5.1.23 and earlier, the MySQL installer places the data
directory directly under the directory where you install MySQL.  On
MySQL 5.1.24 and later, the data directory is located within the
`AppData' directory for the user running MySQL.

If you would like to use a data directory in a different location, you
should copy the entire contents of the `data' directory to the new
location. For example, if you want to use `E:\mydata' as the data
directory instead, you must do two things:

  1. Move the entire `data' directory and all of its contents from the
     default location (for example `C:\Program Files\MySQL\MySQL Server
     6.0\data') to `E:\mydata'.

  2. Use a `--datadir' option to specify the new data directory
     location each time you start the server.


File: manual.info,  Node: windows-select-server,  Next: windows-server-first-start,  Prev: windows-create-option-file,  Up: windows-installation

2.3.8 Selecting a MySQL Server Type
-----------------------------------

The following table shows the available servers for Windows in MySQL
6.0.

*Binary*       *Description*
*Note          Optimized binary with named-pipe support
`mysqld':      
mysqld.        
*Note          Like *Note `mysqld': mysqld, but compiled with full
`mysqld-debug':debugging and automatic memory allocation checking
mysqld.        

All of the preceding binaries are optimized for modern Intel
processors, but should work on any Intel i386-class or higher processor.

Each of the servers in a distribution support the same set of storage
engines. The *Note `SHOW ENGINES': show-engines.  statement displays
which engines a given server supports.

All Windows MySQL 6.0 servers have support for symbolic linking of
database directories.

MySQL supports TCP/IP on all Windows platforms. MySQL servers on
Windows support named pipes as indicated in the following list.
However, the default is to use TCP/IP regardless of platform.  (Named
pipes are slower than TCP/IP in many Windows configurations.)

Named pipes are enabled only if you start the server with the
`--enable-named-pipe' option. It is necessary to use this option
explicitly because some users have experienced problems with shutting
down the MySQL server when named pipes were used.


File: manual.info,  Node: windows-server-first-start,  Next: windows-start-command-line,  Prev: windows-select-server,  Up: windows-installation

2.3.9 Starting the Server for the First Time
--------------------------------------------

This section gives a general overview of starting the MySQL server. The
following sections provide more specific information for starting the
MySQL server from the command line or as a Windows service.

The information here applies primarily if you installed MySQL using the
`Noinstall' version, or if you wish to configure and test MySQL
manually rather than with the GUI tools.

The examples in these sections assume that MySQL is installed under the
default location of `C:\Program Files\MySQL\MySQL Server 6.0'. Adjust
the path names shown in the examples if you have MySQL installed in a
different location.

Clients have two options. They can use TCP/IP, or they can use a named
pipe if the server supports named-pipe connections.

MySQL for Windows also supports shared-memory connections if the server
is started with the `--shared-memory' option. Clients can connect
through shared memory by using the `--protocol=MEMORY' option.

For information about which server binary to run, see *Note
windows-select-server::.

Testing is best done from a command prompt in a console window (or `DOS
window'). In this way you can have the server display status messages
in the window where they are easy to see. If something is wrong with
your configuration, these messages make it easier for you to identify
and fix any problems.

To start the server, enter this command:

     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqld" --console

For a server that includes `InnoDB' support, you should see the
messages similar to those following as it starts (the path names and
sizes may differ):

     InnoDB: The first specified datafile c:\ibdata\ibdata1 did not exist:
     InnoDB: a new database to be created!
     InnoDB: Setting file c:\ibdata\ibdata1 size to 209715200
     InnoDB: Database physically writes the file full: wait...
     InnoDB: Log file c:\iblogs\ib_logfile0 did not exist: new to be created
     InnoDB: Setting log file c:\iblogs\ib_logfile0 size to 31457280
     InnoDB: Log file c:\iblogs\ib_logfile1 did not exist: new to be created
     InnoDB: Setting log file c:\iblogs\ib_logfile1 size to 31457280
     InnoDB: Log file c:\iblogs\ib_logfile2 did not exist: new to be created
     InnoDB: Setting log file c:\iblogs\ib_logfile2 size to 31457280
     InnoDB: Doublewrite buffer not found: creating new
     InnoDB: Doublewrite buffer created
     InnoDB: creating foreign key constraint system tables
     InnoDB: foreign key constraint system tables created
     011024 10:58:25  InnoDB: Started

When the server finishes its startup sequence, you should see something
like this, which indicates that the server is ready to service client
connections:

     mysqld: ready for connections
     Version: '6.0.12'  socket: ''  port: 3306

The server continues to write to the console any further diagnostic
output it produces. You can open a new console window in which to run
client programs.

If you omit the `--console' option, the server writes diagnostic output
to the error log in the data directory (`C:\Program Files\MySQL\MySQL
Server 6.0\data' by default). The error log is the file with the `.err'
extension.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.


File: manual.info,  Node: windows-start-command-line,  Next: windows-start-service,  Prev: windows-server-first-start,  Up: windows-installation

2.3.10 Starting MySQL from the Windows Command Line
---------------------------------------------------

The MySQL server can be started manually from the command line.  This
can be done on any version of Windows.

To start the *Note `mysqld': mysqld. server from the command line, you
should start a console window (or `DOS window') and enter this command:

     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqld"

The path to *Note `mysqld': mysqld. may vary depending on the install
location of MySQL on your system.

You can stop the MySQL server by executing this command:

     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqladmin" -u root shutdown

*Note*:

If the MySQL `root' user account has a password, you need to invoke
*Note `mysqladmin': mysqladmin.  with the `-p' option and supply the
password when prompted.

This command invokes the MySQL administrative utility *Note
`mysqladmin': mysqladmin. to connect to the server and tell it to shut
down. The command connects as the MySQL `root' user, which is the
default administrative account in the MySQL grant system. Note that
users in the MySQL grant system are wholly independent from any login
users under Windows.

If *Note `mysqld': mysqld. doesn't start, check the error log to see
whether the server wrote any messages there to indicate the cause of
the problem. The error log is located in the `C:\Program
Files\MySQL\MySQL Server 6.0\data' directory. It is the file with a
suffix of `.err'. You can also try to start the server as *Note `mysqld
--console': mysqld.; in this case, you may get some useful information
on the screen that may help solve the problem.

The last option is to start *Note `mysqld': mysqld. with the
`--standalone' and `--debug' options. In this case, *Note `mysqld':
mysqld. writes a log file `C:\mysqld.trace' that should contain the
reason why *Note `mysqld': mysqld. doesn't start. See MySQL Internals:
Porting (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

Use *Note `mysqld --verbose --help': mysqld. to display all the options
that *Note `mysqld': mysqld. supports.


File: manual.info,  Node: windows-start-service,  Next: windows-testing,  Prev: windows-start-command-line,  Up: windows-installation

2.3.11 Starting MySQL as a Windows Service
------------------------------------------

On Windows, the recommended way to run MySQL is to install it as a
Windows service, whereby MySQL starts and stops automatically when
Windows starts and stops. A MySQL server installed as a service can
also be controlled from the command line using `NET' commands, or with
the graphical `Services' utility. Generally, to install MySQL as a
Windows service you should be logged in using an account that has
administrator rights.

The `Services' utility (the Windows `Service Control Manager') can be
found in the Windows Control Panel (under `Administrative Tools' on
Windows 2000, XP, Vista, and Server 2003). To avoid conflicts, it is
advisable to close the `Services' utility while performing server
installation or removal operations from the command line.

Before installing MySQL as a Windows service, you should first stop the
current server if it is running by using the following command:

     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqladmin"
               -u root shutdown

*Note*:

If the MySQL `root' user account has a password, you need to invoke
*Note `mysqladmin': mysqladmin.  with the `-p' option and supply the
password when prompted.

This command invokes the MySQL administrative utility *Note
`mysqladmin': mysqladmin. to connect to the server and tell it to shut
down. The command connects as the MySQL `root' user, which is the
default administrative account in the MySQL grant system. Note that
users in the MySQL grant system are wholly independent from any login
users under Windows.

Install the server as a service using this command:

     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqld" --install

The service-installation command does not start the server.
Instructions for that are given later in this section.

To make it easier to invoke MySQL programs, you can add the path name
of the MySQL `bin' directory to your Windows system `PATH' environment
variable:

   * On the Windows desktop, right-click on the `My Computer' icon, and
     select `Properties'.

   * Next select the `Advanced' tab from the `System Properties' menu
     that appears, and click the `Environment Variables' button.

   * Under `System Variables', select `Path', and then click the `Edit'
     button. The `Edit System Variable' dialogue should appear.

   * Place your cursor at the end of the text appearing in the space
     marked `Variable Value'. (Use the `End' key to ensure that your
     cursor is positioned at the very end of the text in this space.)
     Then enter the complete path name of your MySQL `bin' directory
     (for example, `C:\Program Files\MySQL\MySQL Server 6.0\bin'), Note
     that there should be a semicolon separating this path from any
     values present in this field. Dismiss this dialogue, and each
     dialogue in turn, by clicking `OK' until all of the dialogues that
     were opened have been dismissed. You should now be able to invoke
     any MySQL executable program by typing its name at the DOS prompt
     from any directory on the system, without having to supply the
     path. This includes the servers, the *Note `mysql': mysql. client,
     and all MySQL command-line utilities such as *Note `mysqladmin':
     mysqladmin.  and *Note `mysqldump': mysqldump.

     You should not add the MySQL `bin' directory to your Windows
     `PATH' if you are running multiple MySQL servers on the same
     machine.

*Warning*:

You must exercise great care when editing your system `PATH' by hand;
accidental deletion or modification of any portion of the existing
`PATH' value can leave you with a malfunctioning or even unusable
system.

The following additional arguments can be used in MySQL 6.0 when
installing the service:

   * You can specify a service name immediately following the
     `--install' option. The default service name is `MySQL'.

   * If a service name is given, it can be followed by a single option.
     By convention, this should be `--defaults-file=FILE_NAME' to
     specify the name of an option file from which the server should
     read options when it starts.

     The use of a single option other than `--defaults-file' is possible
     but discouraged.  `--defaults-file' is more flexible because it
     enables you to specify multiple startup options for the server by
     placing them in the named option file.

   * You can also specify a `--local-service' option following the
     service name. This causes the server to run using the
     `LocalService' Windows account that has limited system privileges.
     This account is available only for Windows XP or newer. If both
     `--defaults-file' and `--local-service' are given following the
     service name, they can be in any order.

For a MySQL server that is installed as a Windows service, the
following rules determine the service name and option files that the
server uses:

   * If the service-installation command specifies no service name or
     the default service name (`MySQL') following the `--install'
     option, the server uses the a service name of `MySQL' and reads
     options from the `[mysqld]' group in the standard option files.

   * If the service-installation command specifies a service name other
     than `MySQL' following the `--install' option, the server uses that
     service name. It reads options from the `[mysqld]' group and the
     group that has the same name as the service in the standard option
     files. This allows you to use the `[mysqld]' group for options
     that should be used by all MySQL services, and an option group
     with the service name for use by the server installed with that
     service name.

   * If the service-installation command specifies a `--defaults-file'
     option after the service name, the server reads options only from
     the `[mysqld]' group of the named file and ignores the standard
     option files.

As a more complex example, consider the following command:

     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqld"
               --install MySQL --defaults-file=C:\my-opts.cnf

Here, the default service name (`MySQL') is given after the `--install'
option. If no `--defaults-file' option had been given, this command
would have the effect of causing the server to read the `[mysqld]'
group from the standard option files. However, because the
`--defaults-file' option is present, the server reads options from the
`[mysqld]' option group, and only from the named file.

You can also specify options as Start parameters in the Windows
`Services' utility before you start the MySQL service.

Once a MySQL server has been installed as a service, Windows starts the
service automatically whenever Windows starts. The service also can be
started immediately from the `Services' utility, or by using a `NET
START MySQL' command. The `NET' command is not case sensitive.

When run as a service, *Note `mysqld': mysqld. has no access to a
console window, so no messages can be seen there. If *Note `mysqld':
mysqld. does not start, check the error log to see whether the server
wrote any messages there to indicate the cause of the problem. The
error log is located in the MySQL data directory (for example,
`C:\Program Files\MySQL\MySQL Server 6.0\data'). It is the file with a
suffix of `.err'.

When a MySQL server has been installed as a service, and the service is
running, Windows stops the service automatically when Windows shuts
down. The server also can be stopped manually by using the `Services'
utility, the `NET STOP MySQL' command, or the *Note `mysqladmin
shutdown': mysqladmin. command.

You also have the choice of installing the server as a manual service
if you do not wish for the service to be started automatically during
the boot process. To do this, use the `--install-manual' option rather
than the `--install' option:

     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqld" --install-manual

To remove a server that is installed as a service, first stop it if it
is running by executing `NET STOP MySQL'.  Then use the `--remove'
option to remove it:

     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqld" --remove

If *Note `mysqld': mysqld. is not running as a service, you can start
it from the command line. For instructions, see *Note
windows-start-command-line::.

Please see *Note windows-troubleshooting::, if you encounter
difficulties during installation.


File: manual.info,  Node: windows-testing,  Next: windows-troubleshooting,  Prev: windows-start-service,  Up: windows-installation

2.3.12 Testing The MySQL Installation
-------------------------------------

You can test whether the MySQL server is working by executing any of
the following commands:

     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqlshow"
     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqlshow" -u root mysql
     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqladmin" version status proc
     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysql" test

If *Note `mysqld': mysqld. is slow to respond to TCP/IP connections
from client programs, there is probably a problem with your DNS. In
this case, start *Note `mysqld': mysqld.  with the `--skip-name-resolve'
option and use only `localhost' and IP numbers in the `Host' column of
the MySQL grant tables.

You can force a MySQL client to use a named-pipe connection rather than
TCP/IP by specifying the `--pipe' or `--protocol=PIPE' option, or by
specifying `.' (period) as the host name. Use the `--socket' option to
specify the name of the pipe if you do not want to use the default pipe
name.

Note that if you have set a password for the `root' account, deleted
the anonymous account, or created a new user account, then you must use
the appropriate `-u' and `-p' options with the commands shown above in
order to connect with the MySQL Server.  See *Note connecting::.

For more information about *Note `mysqlshow': mysqlshow, see *Note
mysqlshow::.


File: manual.info,  Node: windows-troubleshooting,  Next: windows-upgrading,  Prev: windows-testing,  Up: windows-installation

2.3.13 Troubleshooting a MySQL Installation Under Windows
---------------------------------------------------------

When installing and running MySQL for the first time, you may encounter
certain errors that prevent the MySQL server from starting. The purpose
of this section is to help you diagnose and correct some of these
errors.

Your first resource when troubleshooting server issues is the error
log. The MySQL server uses the error log to record information relevant
to the error that prevents the server from starting. The error log is
located in the data directory specified in your `my.ini' file. The
default data directory location is `C:\Program Files\MySQL\MySQL Server
6.0\data'. See *Note error-log::.

Another source of information regarding possible errors is the console
messages displayed when the MySQL service is starting.  Use the `NET
START MySQL' command from the command line after installing *Note
`mysqld': mysqld. as a service to see any error messages regarding the
starting of the MySQL server as a service. See *Note
windows-start-service::.

The following examples show other common error messages you may
encounter when installing MySQL and starting the server for the first
time:

   * If the MySQL server cannot find the `mysql' privileges database or
     other critical files, you may see these messages:

          System error 1067 has occurred.
          Fatal error: Can't open privilege tables: Table 'mysql.host' doesn't exist

     These messages often occur when the MySQL base or data directories
     are installed in different locations than the default locations
     (`C:\Program Files\MySQL\MySQL Server 6.0' and `C:\Program
     Files\MySQL\MySQL Server 6.0\data', respectively).

     This situation may occur when MySQL is upgraded and installed to a
     new location, but the configuration file is not updated to reflect
     the new location. In addition, there may be old and new
     configuration files that conflict. Be sure to delete or rename any
     old configuration files when upgrading MySQL.

     If you have installed MySQL to a directory other than `C:\Program
     Files\MySQL\MySQL Server 6.0', you need to ensure that the MySQL
     server is aware of this through the use of a configuration
     (`my.ini') file. The `my.ini' file needs to be located in your
     Windows directory, typically `C:\WINDOWS'. You can determine its
     exact location from the value of the `WINDIR' environment variable
     by issuing the following command from the command prompt:

          C:\> echo %WINDIR%

     An option file can be created and modified with any text editor,
     such as Notepad. For example, if MySQL is installed in `E:\mysql'
     and the data directory is `D:\MySQLdata', you can create the option
     file and set up a `[mysqld]' section to specify values for the
     `basedir' and `datadir' options:

          [mysqld]
          # set basedir to your installation path
          basedir=E:/mysql
          # set datadir to the location of your data directory
          datadir=D:/MySQLdata

     Note that Windows path names are specified in option files using
     (forward) slashes rather than backslashes. If you do use
     backslashes, you must double them:

          [mysqld]
          # set basedir to your installation path
          basedir=C:\\Program Files\\MySQL\\MySQL Server 6.0
          # set datadir to the location of your data directory
          datadir=D:\\MySQLdata

     If you change the `datadir' value in your MySQL configuration
     file, you must move the contents of the existing MySQL data
     directory before restarting the MySQL server.

     See *Note windows-create-option-file::.

   * If you reinstall or upgrade MySQL without first stopping and
     removing the existing MySQL service and install MySQL using the
     MySQL Configuration Wizard, you may see this error:

          Error: Cannot create Windows service for MySql. Error: 0

     This occurs when the Configuration Wizard tries to install the
     service and finds an existing service with the same name.

     One solution to this problem is to choose a service name other
     than `mysql' when using the configuration wizard. This allows the
     new service to be installed correctly, but leaves the outdated
     service in place. Although this is harmless, it is best to remove
     old services that are no longer in use.

     To permanently remove the old `mysql' service, execute the
     following command as a user with administrative privileges, on the
     command-line:

          C:\> sc delete mysql
          [SC] DeleteService SUCCESS

     If the `sc' utility is not available for your version of Windows,
     download the `delsrv' utility from
     `http://www.microsoft.com/windows2000/techinfo/reskit/tools/existing/delsrv-o.asp'
     and use the `delsrv mysql' syntax.


File: manual.info,  Node: windows-upgrading,  Next: windows-vs-unix,  Prev: windows-troubleshooting,  Up: windows-installation

2.3.14 Upgrading MySQL on Windows
---------------------------------

This section lists some of the steps you should take when upgrading
MySQL on Windows.

  1. Review *Note upgrade::, for additional information on upgrading
     MySQL that is not specific to Windows.

  2. You should always back up your current MySQL installation before
     performing an upgrade. See *Note backup::.

  3. Download the latest Windows distribution of MySQL from
     `http://dev.mysql.com/downloads/'.

  4. Before upgrading MySQL, you must stop the server. If the server is
     installed as a service, stop the service with the following
     command from the command prompt:

          C:\> NET STOP MySQL

     If you are not running the MySQL server as a service, use the
     following command to stop it:

          C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqladmin" -u root shutdown

     *Note*:

     If the MySQL `root' user account has a password, you need to
     invoke *Note `mysqladmin': mysqladmin.  with the `-p' option and
     supply the password when prompted.

  5. When upgrading to MySQL 6.0 from a version previous to 4.1.5, or
     when upgrading from a version of MySQL installed from a Zip
     archive to a version of MySQL installed with the MySQL
     Installation Wizard, you must manually remove the previous
     installation and MySQL service (if the server is installed as a
     service).

     To remove the MySQL service, use the following command:

          C:\> C:\mysql\bin\mysqld --remove

     *If you do not remove the existing service, the MySQL Installation
     Wizard may fail to properly install the new MySQL service.*

  6. When upgrading from MySQL 5.1.23 to MySQL 5.1.24, the change in
     the default location of the data directory from a directory within
     the MySQL installation to the `AppData' folder means that you must
     manually copy the data files from your old installation to the new
     location.

  7. If you are using the MySQL Installation Wizard, start the wizard
     as described in *Note windows-install-wizard::.

  8. If you are installing MySQL from a Zip archive, extract the
     archive. You may either overwrite your existing MySQL installation
     (usually located at `C:\mysql'), or install it into a different
     directory, such as `C:\mysql5'.  Overwriting the existing
     installation is recommended.

  9. If you were running MySQL as a Windows service and you had to
     remove the service earlier in this procedure, reinstall the
     service. (See *Note windows-start-service::.)

 10. Restart the server. For example, use `NET START MySQL' if you run
     MySQL as a service, or invoke *Note `mysqld': mysqld. directly
     otherwise.

 11. If you encounter errors, see *Note windows-troubleshooting::.


File: manual.info,  Node: windows-vs-unix,  Prev: windows-upgrading,  Up: windows-installation

2.3.15 MySQL on Windows Compared to MySQL on Unix
-------------------------------------------------

MySQL for Windows has proven itself to be very stable. The Windows
version of MySQL has the same features as the corresponding Unix
version, with the following exceptions:

   * *Limited number of ports*

     Windows systems have about 4,000 ports available for client
     connections, and after a connection on a port closes, it takes two
     to four minutes before the port can be reused. In situations where
     clients connect to and disconnect from the server at a high rate,
     it is possible for all available ports to be used up before closed
     ports become available again. If this happens, the MySQL server
     appears to be unresponsive even though it is running. Note that
     ports may be used by other applications running on the machine as
     well, in which case the number of ports available to MySQL is
     lower.

     For more information about this problem, see
     `http://support.microsoft.com/default.aspx?scid=kb;en-us;196271'.

   * *Concurrent reads*

     Before MySQL 6.0.8, the I/O subsystem depends on the `pread()' and
     `pwrite()' system calls to be able to mix *Note `INSERT': insert.
     and *Note `SELECT': select. The server uses mutexes to emulate
     `pread()' and `pwrite()'. The implementation limits the number of
     open files that MySQL can use to 2,048, which means that you
     cannot run as many concurrent threads on Windows as on Unix.

     As of MySQL 6.0.8, native Windows file I/O calls are used, so that
     concurrent reads are more efficiently implemented.  Also, the
     limit of 2,048 open files is removed. The default is 16,384, but
     this can be increased by using the `--open-files-limit' option.

   * *Blocking read*

     MySQL uses a blocking read for each connection. That has the
     following implications if named-pipe connections are enabled:

        * A connection is not disconnected automatically after eight
          hours, as happens with the Unix version of MySQL.

        * If a connection hangs, it is not possible to break it without
          killing MySQL.

        * *Note `mysqladmin kill': mysqladmin. does not work on a
          sleeping connection.

        * *Note `mysqladmin shutdown': mysqladmin. cannot abort as long
          as there are sleeping connections.

     We plan to fix this problem in the future.

   * **Note `ALTER TABLE': alter-table.*

     While you are executing an *Note `ALTER TABLE': alter-table.
     statement, the table is locked from being used by other threads.
     This has to do with the fact that on Windows, you can't delete a
     file that is in use by another thread. In the future, we may find
     some way to work around this problem.

   * **Note `DROP TABLE': drop-table.*

     *Note `DROP TABLE': drop-table. on a table that is in use by a
     `MERGE' table does not work on Windows because the `MERGE' handler
     does the table mapping hidden from the upper layer of MySQL.
     Because Windows does not allow dropping files that are open, you
     first must flush all `MERGE' tables (with *Note `FLUSH TABLES':
     flush.) or drop the `MERGE' table before dropping the table.

   * *`DATA DIRECTORY' and `INDEX DIRECTORY'*

     The `DATA DIRECTORY' and `INDEX DIRECTORY' options for *Note
     `CREATE TABLE': create-table. are ignored on Windows, because
     Windows doesn't support symbolic links. These options also are
     ignored on systems that have a non-functional `realpath()' call.

   * **Note `DROP DATABASE': drop-database.*

     You cannot drop a database that is in use by some thread.

   * *Case-insensitive names*

     File names are not case sensitive on Windows, so MySQL database
     and table names are also not case sensitive on Windows. The only
     restriction is that database and table names must be specified
     using the same case throughout a given statement. See *Note
     identifier-case-sensitivity::.

   * *Directory and file names*

     On Windows, MySQL Server supports only directory and file names
     that are compatible with the current ANSI code pages.  For
     example, the following Japanese directory name will not work in
     the Western locale (code page 1252):

          datadir="C:/维基百科关于中文维基百科"

     The same limitation applies to directory and file names referred
     to in SQL statements, such as the data file path name in *Note
     `LOAD DATA INFILE': load-data.

   * *The ``\'' path name separator character*

     Path name components in Windows are separated by the ``\''
     character, which is also the escape character in MySQL. If you are
     using *Note `LOAD DATA INFILE': load-data. or *Note `SELECT ...
     INTO OUTFILE': select, use Unix-style file names with ``/''
     characters:

          mysql> LOAD DATA INFILE 'C:/tmp/skr.txt' INTO TABLE skr;
          mysql> SELECT * INTO OUTFILE 'C:/tmp/skr.txt' FROM skr;

     Alternatively, you must double the ``\'' character:

          mysql> LOAD DATA INFILE 'C:\\tmp\\skr.txt' INTO TABLE skr;
          mysql> SELECT * INTO OUTFILE 'C:\\tmp\\skr.txt' FROM skr;

   * *Problems with pipes*

     Pipes do not work reliably from the Windows command-line prompt.
     If the pipe includes the character `^Z' / `CHAR(24)', Windows
     thinks that it has encountered end-of-file and aborts the program.

     This is mainly a problem when you try to apply a binary log as
     follows:

          C:\> mysqlbinlog BINARY_LOG_FILE | mysql --user=root

     If you have a problem applying the log and suspect that it is
     because of a `^Z' / `CHAR(24)' character, you can use the
     following workaround:

          C:\> mysqlbinlog BINARY_LOG_FILE --result-file=/tmp/bin.sql
          C:\> mysql --user=root --execute "source /tmp/bin.sql"

     The latter command also can be used to reliably read in any SQL
     file that may contain binary data.

   * *`Access denied for user' error*

     If MySQL cannot resolve your host name properly, you may get the
     following error when you attempt to run a MySQL client program to
     connect to a server running on the same machine:

          Access denied for user 'SOME_USER'@'unknown'
          to database 'mysql'

     To fix this problem, you should create a file named
     `\windows\hosts' containing the following information:

          127.0.0.1       localhost

Here are some open issues for anyone who might want to help us improve
MySQL on Windows:

   * Add macros to use the faster thread-safe increment/decrement
     methods provided by Windows.


File: manual.info,  Node: linux-rpm,  Next: mac-os-x-installation,  Prev: windows-installation,  Up: installing

2.4 Installing MySQL from RPM Packages on Linux
===============================================

The recommended way to install MySQL on RPM-based Linux distributions
is by using the RPM packages. The RPMs that we provide to the community
should work on all versions of Linux that support RPM packages and use
`glibc' 2.3. To obtain RPM packages, see *Note getting-mysql::.

For non-RPM Linux distributions, you can install MySQL using a
`.tar.gz' package. See *Note installing-binary::.

We do provide some platform-specific RPMs; the difference between a
platform-specific RPM and a generic RPM is that a platform-specific RPM
is built on the targeted platform and is linked dynamically whereas a
generic RPM is linked statically with LinuxThreads.

*Note*:

RPM distributions of MySQL often are provided by other vendors.  Be
aware that they may differ in features and capabilities from those
built by us, and that the instructions in this manual do not
necessarily apply to installing them. The vendor's instructions should
be consulted instead.

If you have problems with an RPM file (for example, if you receive the
error `Sorry, the host 'XXXX' could not be looked up'), see *Note
binary-notes-linux::.

In most cases, you need to install only the `MySQL-server' and
`MySQL-client' packages to get a functional MySQL installation. The
other packages are not required for a standard installation.

For upgrades, if your installation was originally produced by
installing multiple RPM packages, it is best to upgrade all the
packages, not just some. For example, if you previously installed the
server and client RPMs, do not upgrade just the server RPM.

If you get a dependency failure when trying to install MySQL packages
(for example, `error: removing these packages would break dependencies:
libmysqlclient.so.10 is needed by ...'), you should also install the
`MySQL-shared-compat' package, which includes both the shared libraries
for backward compatibility (`libmysqlclient.so.12' for MySQL 4.0 and
`libmysqlclient.so.10' for MySQL 3.23).

Some Linux distributions still ship with MySQL 3.23 and they usually
link applications dynamically to save disk space. If these shared
libraries are in a separate package (for example, `MySQL-shared'), it
is sufficient to simply leave this package installed and just upgrade
the MySQL server and client packages (which are statically linked and
do not depend on the shared libraries). For distributions that include
the shared libraries in the same package as the MySQL server (for
example, Red Hat Linux), you could either install our 3.23
`MySQL-shared' RPM, or use the `MySQL-shared-compat' package instead.
(Do not install both.)

The RPM packages shown in the following list are available. The names
shown here use a suffix of `.glibc23.i386.rpm', but particular packages
can have different suffixes, as described later.

   * `MySQL-server-VERSION.glibc23.i386.rpm'

     The MySQL server. You need this unless you only want to connect to
     a MySQL server running on another machine.

   * `MySQL-client-VERSION.glibc23.i386.rpm'

     The standard MySQL client programs. You probably always want to
     install this package.

   * `MySQL-devel-VERSION.glibc23.i386.rpm'

     The libraries and include files that are needed if you want to
     compile other MySQL clients, such as the Perl modules.

   * `MySQL-debuginfo-VERSION.glibc23.i386.rpm'

     This package contains debugging information.  `debuginfo' RPMs are
     never needed to use MySQL software; this is true both for the
     server and for client programs. However, they contain additional
     information that might be needed by a debugger to analyze a crash.

   * `MySQL-shared-VERSION.glibc23.i386.rpm'

     This package contains the shared libraries (`libmysqlclient.so*')
     that certain languages and applications need to dynamically load
     and use MySQL. It contains single-threaded and thread-safe
     libraries. If you install this package, do not install the
     `MySQL-shared-compat' package.

   * `MySQL-shared-compat-VERSION.glibc23.i386.rpm'

     This package includes the shared libraries for MySQL 3.23, 4.0,
     4.1, and 5.1. It contains single-threaded and thread-safe
     libraries. Install this package instead of `MySQL-shared' if you
     have applications installed that are dynamically linked against
     older versions of MySQL but you want to upgrade to the current
     version without breaking the library dependencies.

   * `MySQL-embedded-VERSION.glibc23.i386.rpm'

     The embedded MySQL server library.

   * `MySQL-test-VERSION.glibc23.i386.rpm'

     This package includes the MySQL test suite.

   * `MySQL-VERSION.src.rpm'

     This contains the source code for all of the previous packages. It
     can also be used to rebuild the RPMs on other architectures (for
     example, Alpha or SPARC).

The suffix of RPM package names (following the VERSION value) has the
following syntax:

     .PLATFORM.CPU.rpm

The PLATFORM and CPU values indicate the type of system for which the
package is built.  PLATFORM indicates the platform and CPU indicates
the processor type or family.

All packages are dynamically linked against `glibc' 2.3. The PLATFORM
value indicates whether the package is platform independent or intended
for a specific platform, as shown in the following table.

`glibc23'          Platform independent, should run on any Linux
                   distribution that supports `glibc' 2.3
`rhel3', `rhel4'   Red Hat Enterprise Linux 3 or 4
`sles9', `sles10'  SuSE Linux Enterprise Server 9 or 10

In MySQL 6.0, only `glibc23' packages are available currently.

The CPU value indicates the processor type or family for which the
package is built.

`i386'             x86 processor, 386 and up
`i586'             x86 processor, Pentium and up
`x86_64'           64-bit x86 processor
`ia64'             Itanium (IA-64) processor

To see all files in an RPM package (for example, a `MySQL-server' RPM),
run a command like this:

     shell> rpm -qpl MySQL-server-VERSION.glibc23.i386.rpm

To perform a standard minimal installation, install the server and
client RPMs:

     shell> rpm -i MySQL-server-VERSION.glibc23.i386.rpm
     shell> rpm -i MySQL-client-VERSION.glibc23.i386.rpm

To install only the client programs, install just the client RPM:

     shell> rpm -i MySQL-client-VERSION.glibc23.i386.rpm

RPM provides a feature to verify the integrity and authenticity of
packages before installing them. If you would like to learn more about
this feature, see *Note verifying-package-integrity::.

The server RPM places data under the `/var/lib/mysql' directory. The
RPM also creates a login account for a user named `mysql' (if one does
not exist) to use for running the MySQL server, and creates the
appropriate entries in `/etc/init.d/' to start the server automatically
at boot time. (This means that if you have performed a previous
installation and have made changes to its startup script, you may want
to make a copy of the script so that you don't lose it when you install
a newer RPM.) See *Note automatic-start::, for more information on how
MySQL can be started automatically on system startup.

If you want to install the MySQL RPM on older Linux distributions that
do not support initialization scripts in `/etc/init.d' (directly or via
a symlink), you should create a symbolic link that points to the
location where your initialization scripts actually are installed. For
example, if that location is `/etc/rc.d/init.d', use these commands
before installing the RPM to create `/etc/init.d' as a symbolic link
that points there:

     shell> cd /etc
     shell> ln -s rc.d/init.d .

However, all current major Linux distributions should support the new
directory layout that uses `/etc/init.d', because it is required for
LSB (Linux Standard Base) compliance.

If the RPM files that you install include `MySQL-server', the *Note
`mysqld': mysqld.  server should be up and running after installation.
You should be able to start using MySQL.

If something goes wrong, you can find more information in the binary
installation section. See *Note installing-binary::.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.

During RPM installation, a user named `mysql' and a group named `mysql'
are created on the system.  This is done using the `useradd',
`groupadd', and `usermod' commands. Those commands require appropriate
administrative privileges, which is ensured for locally managed users
and groups (as listed in the `/etc/passwd' and `/etc/group' files) by
the RPM installation process being run by `root'.

For non-local user management (LDAP, NIS, and so forth), the
administrative tools may require additional authentication (such as a
password), and will fail if the installing user does not provide this
authentication. Even if they fail, the RPM installation will not abort
but succeed, and this is intentional.  If they failed, some of the
intended transfer of ownership may be missing, and it is recommended
that the system administrator then manually ensures some appropriate
user andgroup exists and manually transfers ownership following the
actions in the RPM spec file.


File: manual.info,  Node: mac-os-x-installation,  Next: solaris-installation,  Prev: linux-rpm,  Up: installing

2.5 Installing MySQL on Mac OS X
================================

You can install MySQL on Mac OS X 10.3.x (`Panther') or newer using a
Mac OS X binary package in PKG format instead of the binary tarball
distribution. Please note that older versions of Mac OS X (for example,
10.1.x or 10.2.x) are *not* supported by this package.

The package is located inside a disk image (`.dmg') file that you first
need to mount by double-clicking its icon in the Finder. It should then
mount the image and display its contents.

To obtain MySQL, see *Note getting-mysql::.

*Note*:

Before proceeding with the installation, be sure to shut down all
running MySQL server instances by either using the MySQL Manager
Application (on Mac OS X Server) or via *Note `mysqladmin shutdown':
mysqladmin. on the command line.

To actually install the MySQL PKG file, double-click on the package
icon. This launches the Mac OS X Package Installer, which guides you
through the installation of MySQL.

Due to a bug in the Mac OS X package installer, you may see this error
message in the destination disk selection dialog:

     You cannot install this software on this disk. (null)

If this error occurs, simply click the `Go Back' button once to return
to the previous screen. Then click `Continue' to advance to the
destination disk selection again, and you should be able to choose the
destination disk correctly. We have reported this bug to Apple and it is
investigating this problem.

The Mac OS X PKG of MySQL installs itself into
`/usr/local/mysql-VERSION' and also installs a symbolic link,
`/usr/local/mysql', that points to the new location. If a directory
named `/usr/local/mysql' exists, it is renamed to
`/usr/local/mysql.bak' first. Additionally, the installer creates the
grant tables in the `mysql' database by executing *Note
`mysql_install_db': mysql-install-db.

The installation layout is similar to that of a `tar' file binary
distribution; all MySQL binaries are located in the directory
`/usr/local/mysql/bin'. The MySQL socket file is created as
`/tmp/mysql.sock' by default. See *Note installation-layouts::.

MySQL installation requires a Mac OS X user account named `mysql'. A
user account with this name should exist by default on Mac OS X 10.2
and up.

If you are running Mac OS X Server, a version of MySQL should already
be installed. The following table shows the versions of MySQL that ship
with Mac OS X Server versions.

*Mac OS X Server       *MySQL Version*
Version*               
10.2-10.2.2            3.23.51
10.2.3-10.2.6          3.23.53
10.3                   4.0.14
10.3.2                 4.0.16
10.4.0                 4.1.10a

This manual section covers the installation of the official MySQL Mac
OS X PKG only. Make sure to read Apple's help information about
installing MySQL: Run the `Help View' application, select `Mac OS X
Server' help, do a search for `MySQL,' and read the item entitled
`Installing MySQL.'

If you previously used Marc Liyanage's MySQL packages for Mac OS X from
`http://www.entropy.ch', you can simply follow the update instructions
for packages using the binary installation layout as given on his pages.

If you are upgrading from Marc's 3.23.x versions or from the Mac OS X
Server version of MySQL to the official MySQL PKG, you also need to
convert the existing MySQL privilege tables to the current format,
because some new security privileges have been added. See *Note
mysql-upgrade::.

If you want MySQL to start automatically during system startup, you
also need to install the MySQL Startup Item. It is part of the Mac OS X
installation disk images as a separate installation package. Simply
double-click the `MySQLStartupItem.pkg' icon and follow the
instructions to install it. The Startup Item need be installed only
once. There is no need to install it each time you upgrade the MySQL
package later.

The Startup Item for MySQL is installed into
`/Library/StartupItems/MySQLCOM'. (Before MySQL 4.1.2, the location was
`/Library/StartupItems/MySQL', but that collided with the MySQL Startup
Item installed by Mac OS X Server.) Startup Item installation adds a
variable `MYSQLCOM=-YES-' to the system configuration file
`/etc/hostconfig'. If you want to disable the automatic startup of
MySQL, simply change this variable to `MYSQLCOM=-NO-'.

On Mac OS X Server, the default MySQL installation uses the variable
`MYSQL' in the `/etc/hostconfig' file. The MySQL Startup Item installer
disables this variable by setting it to `MYSQL=-NO-'. This avoids boot
time conflicts with the `MYSQLCOM' variable used by the MySQL Startup
Item. However, it does not shut down a running MySQL server. You should
do that yourself.

After the installation, you can start up MySQL by running the following
commands in a terminal window. You must have administrator privileges
to perform this task.

If you have installed the Startup Item, use this command:

     shell> sudo /Library/StartupItems/MySQLCOM/MySQLCOM start
     (ENTER YOUR PASSWORD, IF NECESSARY)
     (PRESS CONTROL-D OR ENTER "EXIT" TO EXIT THE SHELL)

If you don't use the Startup Item, enter the following command sequence:

     shell> cd /usr/local/mysql
     shell> sudo ./bin/mysqld_safe
     (ENTER YOUR PASSWORD, IF NECESSARY)
     (PRESS CONTROL-Z)
     shell> bg
     (PRESS CONTROL-D OR ENTER "EXIT" TO EXIT THE SHELL)

You should be able to connect to the MySQL server, for example, by
running `/usr/local/mysql/bin/mysql'.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.

You might want to add aliases to your shell's resource file to make it
easier to access commonly used programs such as *Note `mysql': mysql.
and *Note `mysqladmin': mysqladmin. from the command line. The syntax
for `bash' is:

     alias mysql=/usr/local/mysql/bin/mysql
     alias mysqladmin=/usr/local/mysql/bin/mysqladmin

For `tcsh', use:

     alias mysql /usr/local/mysql/bin/mysql
     alias mysqladmin /usr/local/mysql/bin/mysqladmin

Even better, add `/usr/local/mysql/bin' to your `PATH' environment
variable. You can do this by modifying the appropriate startup file for
your shell. For more information, see *Note invoking-programs::.

If you are upgrading an existing installation, note that installing a
new MySQL PKG does not remove the directory of an older installation.
Unfortunately, the Mac OS X Installer does not yet offer the
functionality required to properly upgrade previously installed
packages.

To use your existing databases with the new installation, you'll need
to copy the contents of the old data directory to the new data
directory. Make sure that neither the old server nor the new one is
running when you do this. After you have copied over the MySQL database
files from the previous installation and have successfully started the
new server, you should consider removing the old installation files to
save disk space. Additionally, you should also remove older versions of
the Package Receipt directories located in
`/Library/Receipts/mysql-VERSION.pkg'.


File: manual.info,  Node: solaris-installation,  Next: netware-installation,  Prev: mac-os-x-installation,  Up: installing

2.6 Installing MySQL on Solaris
===============================

To obtain a binary MySQL distribution for Solaris in tarball or PKG
format, `http://dev.mysql.com/downloads/mysql/6.0.html'.

If you install MySQL using a binary tarball distribution on Solaris,
you may run into trouble even before you get the MySQL distribution
unpacked, as the Solaris `tar' cannot handle long file names. This
means that you may see errors when you try to unpack MySQL.

If this occurs, you must use GNU `tar' (`gtar') to unpack the
distribution.

You can install MySQL on Solaris using a binary package in PKG format
instead of the binary tarball distribution. Before installing using the
binary PKG format, you should create the `mysql' user and group, for
example:

     groupadd mysql
     useradd -g mysql mysql

Some basic PKG-handling commands follow:

   * To add a package:

          pkgadd -d PACKAGE_NAME.pkg

   * To remove a package:

          pkgrm PACKAGE_NAME

   * To get a full list of installed packages:

          pkginfo

   * To get detailed information for a package:

          pkginfo -l PACKAGE_NAME

   * To list the files belonging to a package:

          pkgchk -v PACKAGE_NAME

   * To get packaging information for an arbitrary file:

          pkgchk -l -p FILE_NAME

For additional information about installing MySQL on Solaris, see *Note
solaris::.


File: manual.info,  Node: netware-installation,  Next: installing-binary,  Prev: solaris-installation,  Up: installing

2.7 Installing MySQL on NetWare
===============================

Porting MySQL to NetWare was an effort spearheaded by Novell.  Novell
customers should be pleased to note that NetWare 6.5 ships with bundled
MySQL binaries, complete with an automatic commercial use license for
all servers running that version of NetWare.

MySQL for NetWare is compiled using a combination of Metrowerks
CodeWarrior for NetWare and special cross-compilation versions of the
GNU autotools.

The latest binary packages for NetWare can be obtained at
`http://dev.mysql.com/downloads/'. See *Note getting-mysql::.

To host MySQL, the NetWare server must meet these requirements:

   * The latest Support Pack of NetWare 6.5
     (http://support.novell.com/filefinder/18197/index.html) must be
     installed.

   * The system must meet Novell's minimum requirements to run the
     respective version of NetWare.

   * MySQL data and the program binaries must be installed on an NSS
     volume; traditional volumes are not supported.

To install MySQL for NetWare, use the following procedure:

  1. If you are upgrading from a prior installation, stop the MySQL
     server. This is done from the server console, using the following
     command:

          SERVER:  mysqladmin -u root shutdown

     *Note*:

     If the MySQL `root' user account has a password, you need to
     invoke *Note `mysqladmin': mysqladmin.  with the `-p' option and
     supply the password when prompted.

  2. Log on to the target server from a client machine with access to
     the location where you are installing MySQL.

  3. Extract the binary package Zip file onto the server. Be sure to
     allow the paths in the Zip file to be used. It is safe to simply
     extract the file to `SYS:\'.

     If you are upgrading from a prior installation, you may need to
     copy the data directory (for example, `SYS:MYSQL\DATA'), as well as
     `my.cnf', if you have customized it. You can then delete the old
     copy of MySQL.

  4. You might want to rename the directory to something more
     consistent and easy to use. The examples in this manual use
     `SYS:MYSQL' to refer to the installation directory.

     Note that MySQL installation on NetWare does not detect if a
     version of MySQL is already installed outside the NetWare release.
     Therefore, if you have installed the latest MySQL version from the
     Web (for example, MySQL 4.1 or later) in `SYS:\MYSQL', you must
     rename the folder before upgrading the NetWare server; otherwise,
     files in `SYS:\MySQL' are overwritten by the MySQL version present
     in NetWare Support Pack.

  5. At the server console, add a search path for the directory
     containing the MySQL NLMs. For example:

          SERVER:  SEARCH ADD SYS:MYSQL\BIN

  6. Initialize the data directory and the grant tables, if necessary,
     by executing *Note `mysql_install_db': mysql-install-db. at the
     server console.

  7. Start the MySQL server using *Note `mysqld_safe': mysqld-safe. at
     the server console.

  8. To finish the installation, you should also add the following
     commands to `autoexec.ncf'. For example, if your MySQL
     installation is in `SYS:MYSQL' and you want MySQL to start
     automatically, you could add these lines:

          #Starts the MySQL 6.0.x database server
          SEARCH ADD SYS:MYSQL\BIN
          MYSQLD_SAFE

     If you are running MySQL on NetWare 6.0, we strongly suggest that
     you use the `--skip-external-locking' option on the command line:

          #Starts the MySQL 6.0.x database server
          SEARCH ADD SYS:MYSQL\BIN
          MYSQLD_SAFE --skip-external-locking

     It is also necessary to use *Note `CHECK TABLE': check-table. and
     *Note `REPAIR TABLE': repair-table. instead of *Note `myisamchk':
     myisamchk, because *Note `myisamchk': myisamchk. makes use of
     external locking. External locking is known to have problems on
     NetWare 6.0; the problem has been eliminated in NetWare 6.5. Note
     that the use of MySQL on Netware 6.0 is not officially supported.

     *Note `mysqld_safe': mysqld-safe. on NetWare provides a screen
     presence. When you unload (shut down) the *Note `mysqld_safe':
     mysqld-safe. NLM, the screen does not go away by default. Instead,
     it prompts for user input:

          *<NLM has terminated; Press any key to close the screen>*

     If you want NetWare to close the screen automatically instead, use
     the `--autoclose' option to *Note `mysqld_safe': mysqld-safe. For
     example:

          #Starts the MySQL 6.0.x database server
          SEARCH ADD SYS:MYSQL\BIN
          MYSQLD_SAFE --autoclose

     The behavior of *Note `mysqld_safe': mysqld-safe. on NetWare is
     described further in *Note mysqld-safe::.

  9. When installing MySQL, either for the first time or upgrading from
     a previous version, download and install the latest and
     appropriate Perl module and PHP extensions for NetWare:

        * Perl:
          `http://forge.novell.com/modules/xfcontent/downloads.php/perl/Modules/'

        * PHP:
          `http://forge.novell.com/modules/xfcontent/downloads.php/php/Modules/'

If there was an existing installation of MySQL on the NetWare server,
be sure to check for existing MySQL startup commands in `autoexec.ncf',
and edit or delete them as necessary.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.


File: manual.info,  Node: installing-binary,  Next: installing-source,  Prev: netware-installation,  Up: installing

2.8 Installing MySQL from `tar.gz' Packages on Other Unix-Like Systems
======================================================================

This section covers the installation of MySQL binary distributions that
are provided for various platforms in the form of compressed `tar'
files (files with a `.tar.gz' extension). See *Note mysql-binaries::,
for a detailed list.

To obtain MySQL, see *Note getting-mysql::.

MySQL `tar' file binary distributions have names of the form
`mysql-VERSION-OS.tar.gz', where `VERSION' is a number (for example,
`6.0.12'), and OS indicates the type of operating system for which the
distribution is intended (for example, `pc-linux-i686').

In addition to these generic packages, we also offer binaries in
platform-specific package formats for selected platforms. See *Note
quick-standard-installation::, for more information on how to install
these.

You need the following tools to install a MySQL `tar' file binary
distribution:

   * GNU `gunzip' to uncompress the distribution.

   * A reasonable `tar' to unpack the distribution. GNU `tar' is known
     to work.  Some operating systems come with a preinstalled version
     of `tar' that is known to have problems. For example, the `tar'
     provided with early versions of Mac OS X, SunOS 4.x and Solaris 8
     and earlier are known to have problems with long file names. On
     Mac OS X, you can use the preinstalled `gnutar' program. On other
     systems with a deficient `tar', you should install GNU `tar' first.

If you run into problems and need to file a bug report, please use the
instructions in *Note bug-reports::.

The basic commands that you must execute to install and use a MySQL
binary distribution are:

     shell> groupadd mysql
     shell> useradd -g mysql mysql
     shell> cd /usr/local
     shell> gunzip < /PATH/TO/MYSQL-VERSION-OS.tar.gz | tar xvf -
     shell> ln -s FULL-PATH-TO-MYSQL-VERSION-OS mysql
     shell> cd mysql
     shell> chown -R mysql .
     shell> chgrp -R mysql .
     shell> scripts/mysql_install_db --user=mysql
     shell> chown -R root .
     shell> chown -R mysql data
     shell> bin/mysqld_safe --user=mysql &

*Note*:

This procedure does not set up any passwords for MySQL accounts.  After
following the procedure, proceed to *Note post-installation::.

A more detailed version of the preceding description for installing a
binary distribution follows:

  1. Add a login user and group for *Note `mysqld': mysqld. to run as:

          shell> groupadd mysql
          shell> useradd -g mysql mysql

     These commands add the `mysql' group and the `mysql' user. The
     syntax for `useradd' and `groupadd' may differ slightly on
     different versions of Unix, or they may have different names such
     as `adduser' and `addgroup'.

     You might want to call the user and group something else instead
     of `mysql'. If so, substitute the appropriate name in the
     following steps.

  2. Pick the directory under which you want to unpack the distribution
     and change location into it. In the following example, we unpack
     the distribution under `/usr/local'. (The instructions, therefore,
     assume that you have permission to create files and directories in
     `/usr/local'. If that directory is protected, you must perform the
     installation as `root'.)

          shell> cd /usr/local

  3. Obtain a distribution file using the instructions in *Note
     getting-mysql::. For a given release, binary distributions for all
     platforms are built from the same MySQL source distribution.

  4. Unpack the distribution, which creates the installation directory.
     Then create a symbolic link to that directory:

          shell> gunzip < /PATH/TO/MYSQL-VERSION-OS.tar.gz | tar xvf -
          shell> ln -s FULL-PATH-TO-MYSQL-VERSION-OS mysql

     The `tar' command creates a directory named `mysql-VERSION-OS'.
     The `ln' command makes a symbolic link to that directory. This
     lets you refer more easily to the installation directory as
     `/usr/local/mysql'.

     With GNU `tar', no separate invocation of `gunzip' is necessary.
     You can replace the first line with the following alternative
     command to uncompress and extract the distribution:

          shell> tar zxvf /PATH/TO/MYSQL-VERSION-OS.tar.gz

  5. Change location into the installation directory:

          shell> cd mysql

     You will find several files and subdirectories in the `mysql'
     directory. The most important for installation purposes are the
     `bin' and `scripts' subdirectories:

        * The `bin' directory contains client programs and the server.
          You should add the full path name of this directory to your
          `PATH' environment variable so that your shell finds the MySQL
          programs properly. See *Note environment-variables::.

        * The `scripts' directory contains the *Note
          `mysql_install_db': mysql-install-db. script used to
          initialize the `mysql' database containing the grant tables
          that store the server access permissions.

  6. Ensure that the distribution contents are accessible to `mysql'.
     If you unpacked the distribution as `mysql', no further action is
     required. If you unpacked the distribution as `root', its contents
     will be owned by `root'. Change its ownership to `mysql' by
     executing the following commands as `root' in the installation
     directory:

          shell> chown -R mysql .
          shell> chgrp -R mysql .

     The first command changes the owner attribute of the files to the
     `mysql' user. The second changes the group attribute to the
     `mysql' group.

  7. If you have not installed MySQL before, you must create the MySQL
     data directory and initialize the grant tables:

          shell> scripts/mysql_install_db --user=mysql

     If you run the command as `root', include the `--user' option as
     shown. If you run the command while logged in as that user, you
     can omit the `--user' option.

     The command should create the data directory and its contents with
     `mysql' as the owner.

     After creating or updating the grant tables, you need to restart
     the server manually.

  8. Most of the MySQL installation can be owned by `root' if you like.
     The exception is that the data directory must be owned by `mysql'.
     To accomplish this, run the following commands as `root' in the
     installation directory:

          shell> chown -R root .
          shell> chown -R mysql data

  9. If you want MySQL to start automatically when you boot your
     machine, you can copy `support-files/mysql.server' to the location
     where your system has its startup files. More information can be
     found in the `support-files/mysql.server' script itself and in
     *Note automatic-start::.

 10. You can set up new accounts using the `bin/mysql_setpermission'
     script if you install the `DBI' and `DBD::mysql' Perl modules. See
     *Note mysql-setpermission::. For Perl module installation
     instructions, see *Note perl-support::.

 11. If you would like to use *Note `mysqlaccess': mysqlaccess. and
     have the MySQL distribution in some non-standard location, you
     must change the location where *Note `mysqlaccess': mysqlaccess.
     expects to find the *Note `mysql': mysql. client. Edit the
     `bin/mysqlaccess' script at approximately line 18. Search for a
     line that looks like this:

          $MYSQL     = '/usr/local/bin/mysql';    # path to mysql executable

     Change the path to reflect the location where *Note `mysql':
     mysql. actually is stored on your system. If you do not do this, a
     `Broken pipe' error will occur when you run *Note `mysqlaccess':
     mysqlaccess.

After everything has been unpacked and installed, you should test your
distribution. To start the MySQL server, use the following command:

     shell> bin/mysqld_safe --user=mysql &

If you run the command as `root', you must use the `--user' option as
shown. The value of the option is the name of the login account that
you created in the first step to use for running the server. If you run
the command while logged in as `mysql', you can omit the `--user'
option.

If the command fails immediately and prints `mysqld ended', you can
find some information in the `HOST_NAME.err' file in the data directory.

More information about *Note `mysqld_safe': mysqld-safe. is given in
*Note mysqld-safe::.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.


File: manual.info,  Node: installing-source,  Next: post-installation,  Prev: installing-binary,  Up: installing

2.9 MySQL Installation Using a Source Distribution
==================================================

* Menu:

* quick-install::                Source Installation Overview
* configure-options::            Typical `configure' Options
* installing-source-tree::       Installing from the Development Source Tree
* compilation-problems::         Dealing with Problems Compiling MySQL
* mit-pthreads::                 MIT-pthreads Notes
* windows-source-build::         Installing MySQL from Source on Windows
* windows-client-compiling::     Compiling MySQL Clients on Windows

Before you proceed with an installation from source, first check
whether our binary is available for your platform and whether it works
for you. We put a great deal of effort into ensuring that our binaries
are built with the best possible options.

To obtain a source distribution for MySQL, *Note getting-mysql::. If
you want to build MySQL from source on Windows, see *Note
windows-source-build::.

MySQL source distributions are provided as compressed `tar' archives
and have names of the form `mysql-VERSION.tar.gz', where VERSION is a
number like `6.0.12'.

You need the following tools to build and install MySQL from source:

   * GNU `gunzip' to uncompress the distribution.

   * A reasonable `tar' to unpack the distribution. GNU `tar' is known
     to work.  Some operating systems come with a preinstalled version
     of `tar' that is known to have problems. For example, the `tar'
     provided with early versions of Mac OS X, SunOS 4.x and Solaris 8
     and earlier are known to have problems with long file names. On
     Mac OS X, you can use the preinstalled `gnutar' program. On other
     systems with a deficient `tar', you should install GNU `tar' first.

   * A working ANSI C++ compiler. `gcc' 2.95.2 or later, SGI C++, and
     SunPro C++ are some of the compilers that are known to work.
     `libg++' is not needed when using `gcc'. `gcc' 2.7.x has a bug
     that makes it impossible to compile some perfectly legal C++
     files, such as `sql/sql_base.cc'. If you have only `gcc' 2.7.x,
     you must upgrade your `gcc' to be able to compile MySQL.  `gcc'
     2.8.1 is also known to have problems on some platforms, so it
     should be avoided if a new compiler exists for the platform. `gcc'
     2.95.2 or later is recommended.

   * A good `make' program. GNU `make' is always recommended and is
     sometimes required. (BSD `make' fails, and vendor-provided `make'
     implementations may fail as well.) If you have problems, we
     recommend GNU `make' 3.75 or newer.

   * `libtool' 1.5.24 or later is also recommended.

     This is particularly true when building 64-bit binaries on Solaris
     for x86_64 processors (see Bug#31268
     (http://bugs.mysql.com/31268)). In addition, to guarantee that the
     binaries are 64-bit, you should do the following:

        * Provide `--build=x86_64-pc-solaris2.10' as a `configure'
          argument.

        * Provide `-m64' as part of CFLAGS, CXXFLAGS and LDFLAGS

        * Run `configure' and `make' as shown here:

               % LIBRARY_PATH=/usr/local/lib/amd64 ./configure .....
               % LIBRARY_PATH=/usr/local/lib/amd64 gmake

If you are using a version of `gcc' recent enough to understand the
`-fno-exceptions' option, it is _very important_ that you use this
option.  Otherwise, you may compile a binary that crashes randomly. We
also recommend that you use `-felide-constructors' and `-fno-rtti'
along with `-fno-exceptions'. When in doubt, do the following:

     CFLAGS="-O3" CXX=gcc CXXFLAGS="-O3 -felide-constructors \
            -fno-exceptions -fno-rtti" ./configure \
            --prefix=/usr/local/mysql --enable-assembler \
            --with-mysqld-ldflags=-all-static

On most systems, this gives you a fast and stable binary.

If you run into problems and need to file a bug report, please use the
instructions in *Note bug-reports::.


File: manual.info,  Node: quick-install,  Next: configure-options,  Prev: installing-source,  Up: installing-source

2.9.1 Source Installation Overview
----------------------------------

The basic commands that you must execute to install a MySQL source
distribution are:

     shell> groupadd mysql
     shell> useradd -g mysql mysql
     shell> gunzip < mysql-VERSION.tar.gz | tar -xvf -
     shell> cd mysql-VERSION
     shell> ./configure --prefix=/usr/local/mysql
     shell> make
     shell> make install
     shell> cp support-files/my-medium.cnf /etc/my.cnf
     shell> cd /usr/local/mysql
     shell> chown -R mysql .
     shell> chgrp -R mysql .
     shell> bin/mysql_install_db --user=mysql
     shell> chown -R root .
     shell> chown -R mysql var
     shell> bin/mysqld_safe --user=mysql &

If you start from a source RPM, do the following:

     shell> rpmbuild --rebuild --clean MySQL-VERSION.src.rpm

This makes a binary RPM that you can install. For older versions of
RPM, you may have to replace the command `rpmbuild' with `rpm' instead.

*Note*:

This procedure does not set up any passwords for MySQL accounts. After
following the procedure, proceed to *Note post-installation::, for
post-installation setup and testing.

A more detailed version of the preceding description for installing
MySQL from a source distribution follows:

  1. Add a login user and group for *Note `mysqld': mysqld. to run as:

          shell> groupadd mysql
          shell> useradd -g mysql mysql

     These commands add the `mysql' group and the `mysql' user. The
     syntax for `useradd' and `groupadd' may differ slightly on
     different versions of Unix, or they may have different names such
     as `adduser' and `addgroup'.

     You might want to call the user and group something else instead
     of `mysql'. If so, substitute the appropriate name in the
     following steps.

  2. Perform the following steps as the `mysql' user, except as noted.

  3. Pick the directory under which you want to unpack the distribution
     and change location into it.

  4. Obtain a distribution file using the instructions in *Note
     getting-mysql::.

  5. Unpack the distribution into the current directory:

          shell> gunzip < /PATH/TO/MYSQL-VERSION.tar.gz | tar xvf -

     This command creates a directory named `mysql-VERSION'.

     With GNU `tar', no separate invocation of `gunzip' is necessary.
     You can use the following alternative command to uncompress and
     extract the distribution:

          shell> tar zxvf /PATH/TO/MYSQL-VERSION-OS.tar.gz

  6. Change location into the top-level directory of the unpacked
     distribution:

          shell> cd mysql-VERSION

     Note that currently you must configure and build MySQL from this
     top-level directory. You cannot build it in a different directory.

  7. Configure the release and compile everything:

          shell> ./configure --prefix=/usr/local/mysql
          shell> make

     When you run `configure', you might want to specify other options.
     Run `./configure --help' for a list of options.  *Note
     configure-options::, discusses some of the more useful options.

     If `configure' fails and you are going to send mail to a MySQL
     mailing list to ask for assistance, please include any lines from
     `config.log' that you think can help solve the problem. Also
     include the last couple of lines of output from `configure'. To
     file a bug report, please use the instructions in *Note
     bug-reports::.

     If the compile fails, see *Note compilation-problems::, for help.

  8. Install the distribution:

          shell> make install

     You might need to run this command as `root'.

     If you want to set up an option file, use one of those present in
     the `support-files' directory as a template. For example:

          shell> cp support-files/my-medium.cnf /etc/my.cnf

     You might need to run this command as `root'.

     If you want to configure support for `InnoDB' tables, you should
     edit the `/etc/my.cnf' file, remove the `#' character before the
     option lines that start with `innodb_...', and modify the option
     values to be what you want. See *Note option-files::, and *Note
     innodb-configuration::.

  9. Change location into the installation directory:

          shell> cd /usr/local/mysql

 10. If you ran the `make install' command as `root', the installed
     files will be owned by `root'. Ensure that the installation is
     accessible to `mysql' by executing the following commands as
     `root' in the installation directory:

          shell> chown -R mysql .
          shell> chgrp -R mysql .

     The first command changes the owner attribute of the files to the
     `mysql' user. The second changes the group attribute to the
     `mysql' group.

 11. If you have not installed MySQL before, you must create the MySQL
     data directory and initialize the grant tables:

          shell> bin/mysql_install_db --user=mysql

     If you run the command as `root', include the `--user' option as
     shown. If you run the command while logged in as `mysql', you can
     omit the `--user' option.

     The command should create the data directory and its contents with
     `mysql' as the owner.

     After using *Note `mysql_install_db': mysql-install-db. to create
     the grant tables for MySQL, you must restart the server manually.
     The *Note `mysqld_safe': mysqld-safe. command to do this is shown
     in a later step.

 12. Most of the MySQL installation can be owned by `root' if you like.
     The exception is that the data directory must be owned by `mysql'.
     To accomplish this, run the following commands as `root' in the
     installation directory:

          shell> chown -R root .
          shell> chown -R mysql var

 13. If you want MySQL to start automatically when you boot your
     machine, you can copy `support-files/mysql.server' to the location
     where your system has its startup files. More information can be
     found in the `support-files/mysql.server' script itself; see also
     *Note automatic-start::.

 14. You can set up new accounts using the `bin/mysql_setpermission'
     script if you install the `DBI' and `DBD::mysql' Perl modules. See
     *Note mysql-setpermission::. For Perl module installation
     instructions, see *Note perl-support::.

After everything has been installed, you should test your distribution.
To start the MySQL server, use the following command:

     shell> /usr/local/mysql/bin/mysqld_safe --user=mysql &

If you run the command as `root', you should use the `--user' option as
shown. The value of the option is the name of the login account that
you created in the first step to use for running the server. If you run
the command while logged in as that user, you can omit the `--user'
option.

If the command fails immediately and prints `mysqld ended', you can
find some information in the `HOST_NAME.err' file in the data directory.

More information about *Note `mysqld_safe': mysqld-safe. is given in
*Note mysqld-safe::.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.


File: manual.info,  Node: configure-options,  Next: installing-source-tree,  Prev: quick-install,  Up: installing-source

2.9.2 Typical `configure' Options
---------------------------------

The `configure' script gives you a great deal of control over how you
configure a MySQL source distribution.  Typically you do this using
options on the `configure' command line. You can also affect
`configure' using certain environment variables. See *Note
environment-variables::. For a full list of options supported by
`configure', run this command:

     shell> ./configure --help

A list of the available `configure' options is provided in the table
below.

*Build (`configure') Reference*

*Formats*              *Description*          *Default*      *Introduced**Removed*
-bindir=DIR            User executables       EPREFIX/bin            
-build=BUILD           Configure for          guessed                
                       building on BUILD                             
-cache-file=FILE       Cache test results in  disabled               
                       FILE                                          
-C                     Alias for                                     
                       `-cache-file=config.cache'                       
-config-cache                                                        
-datadir=DIR           Read-only              PREFIX/share           
                       architecture-independent                       
                       data                                          
-disable-FEATURE       Do not include FEATURE                        
-disable-dependency-trackingDisable dependency                            
                       tracking                                      
-disable-grant-options Disable GRANT options                         
-disable-largefile     Omit support for                              
                       large files                                   
-disable-libtool-lock  Disable libtool lock                          
-disable-thread-safe-clientCompile the client                            
                       without threads                               
-enable-FEATURE        Enable FEATURE                                
-enable-assembler      Use assembler                                 
                       versions of some                              
                       string functions if                           
                       available                                     
-enable-debug-sync     Compile in Debug Sync                 6.0.6   
                       facility                                      
-enable-dependency-trackingDo not reject slow                            
                       dependency extractors                         
-enable-dtrace         Compile in DTrace                     6.0.4   
                       support                                       
-enable-fast-install   Optimize for fast      yes                    
                       installation                                  
-enable-local-infile   Enable LOAD DATA       disabled               
                       LOCAL INFILE                                  
-enable-shared         Build shared libraries yes                    
-enable-static         Build static libraries yes                    
-enable-thread-safe-clientCompile the client                            
                       with threads                                  
-exec-prefix=EPREFIX   Install                                       
                       architecture-dependent                        
                       files in EPREFIX                              
-h                     Display this help and                         
                       exit                                          
-help                                                                
-help=short            Display options                               
                       specific to this                              
                       package                                       
-help=recursive        Display the short                             
                       help of all the                               
                       included packages                             
-host=HOST             Cross-compile to                              
                       build programs to run                         
                       on HOST                                       
-includedir=DIR        C header files         PREFIX/include         
-infodir=DIR           Info documentation     PREFIX/info            
-libdir=DIR            Object code libraries  EPREFIX/lib            
-libexecdir=DIR        Program executables    EPREFIX/libexec        
-localstatedir=DIR     Modifiable             PREFIX/var             
                       single-machine data                           
-mandir=DIR            man documentation      PREFIX/man             
-n                     Do not create output                          
                       files                                         
-no-create                                                           
-oldincludedir=DIR     C header files for     /usr/include           
                       non-gcc                                       
-prefix=PREFIX         Install                                       
                       architecture-independent                       
                       files in PREFIX                               
-program-prefix=PREFIX Prepend PREFIX to                             
                       installed program                             
                       names                                         
-program-suffix=SUFFIX Append SUFFIX to                              
                       installed program                             
                       names                                         
-program-transform-name=PROGRAMrun sed PROGRAM on                            
                       installed program                             
                       names                                         
-q                     Do not print                                  
                       `checking...' messages                        
-quiet                                                               
-sbindir=DIR           System admin           EPREFIX/sbin           
                       executables                                   
-sharedstatedir=DIR    Modifiable             PREFIX/com             
                       architecture-independent                       
                       data                                          
-srcdir=DIR            Find the sources in    configure              
                       DIR                    directory or           
                                              ..                     
-sysconfdir=DIR        Read-only              PREFIX/etc             
                       single-machine data                           
-target=TARGET         Configure for                                 
                       building compilers                            
                       for TARGET                                    
-V                     Display version                               
                       information and exit                          
-version                                                             
-with-PACKAGE          Use PACKAGE                                   
-with-archive-storage-engineEnable the Archive     no                     
                       Storage Engine                                
-with-atomic-ops       Implement atomic                              
                       operations using                              
                       pthread rwlocks or                            
                       atomic CPU                                    
                       instructions for                              
                       multi-processor                               
-with-berkeley-db      Use BerkeleyDB         no                     
                       located in DIR                                
-with-berkeley-db-includesFind Berkeley DB                              
                       headers in DIR                                
-with-berkeley-db-libs Find Berkeley DB                              
                       libraries in DIR                              
-with-big-tables       Support tables with                           
                       more than 4 G rows                            
                       even on 32 bit                                
                       platforms                                     
-with-blackhole-storage-engineEnable the Blackhole   no                     
                       Storage Engine                                
-with-charset          Default character set                         
-with-client-ldflags   Extra linking                                 
                       arguments for clients                         
-with-collation        Default collation                             
-with-comment          Comment about                                 
                       compilation                                   
                       environment                                   
-with-csv-storage-engineEnable the CSV         yes                    
                       Storage Engine                                
-with-darwin-mwcc      Use Metrowerks                                
                       CodeWarrior wrappers                          
                       on OS X/Darwin                                
-with-debug            Add debug code                                
-with-debug=full       Add debug code (adds                          
                       memory checker, very                          
                       slow)                                         
-with-embedded-privilege-controlBuild parts to check                          
                       user's privileges                             
                       (only affects                                 
                       embedded library)                             
-with-embedded-server  Build the embedded                            
                       server                                        
-with-error-inject     Enable error                                  
                       injection in MySQL                            
                       Server                                        
-with-example-storage-engineEnable the Example     no                     
                       Storage Engine                                
-with-extra-charsets   Use charsets in                               
                       addition to default                           
-with-fast-mutexes     Compile with fast      enabled                
                       mutexes                                       
-with-federated-storage-engineEnable federated       no                     
                       storage engine                                
-with-gnu-ld           Assume the C compiler  no                     
                       uses GNU ld                                   
-with-innodb           Enable innobase        no                     
                       storage engine                                
-with-lib-ccflags      Extra CC options for                          
                       libraries                                     
-with-libevent         Include libevent for                  6.0.4   
                       thread-pool support                           
-with-low-memory       Try to use less                               
                       memory to compile to                          
                       avoid memory                                  
                       limitations                                   
-with-machine-type     Set the machine type,                         
                       like "powerpc"                                
-with-maria-temp-tablesMake the temporary                    6.0.6   
                       tables within MySQL                           
                       use the Maria storage                         
                       engine                                        
-with-max-indexes=N    Sets the maximum       64                     
                       number of indexes per                         
                       table                                         
-with-mysqld-ldflags   Extra linking                                 
                       arguments for mysqld                          
-with-mysqld-libs      Extra libraries to                            
                       link with for mysqld                          
-with-mysqld-user      What user the mysqld                          
                       daemon shall be run as                        
-with-mysqlmanager     Build the              Build if               
                       mysqlmanager binary    server is              
                                              built                  
-with-named-curses-libsUse specified curses                          
                       libraries                                     
-with-named-thread-libsUse specified thread                          
                       libraries                                     
-with-ndb-ccflags      Extra CC options for                          
                       ndb compile                                   
-with-ndb-docs         Include the NDB                               
                       Cluster ndbapi and                            
                       mgmapi documentation                          
-with-ndb-port         Port for NDB Cluster                          
                       management server                             
-with-ndb-port-base    Port for NDB Cluster                          
                       management server                             
-with-ndb-sci=DIR      Provide MySQL with a                          
                       custom location of                            
                       sci library                                   
-with-ndb-test         Include the NDB                               
                       Cluster ndbapi test                           
                       programs                                      
-with-ndbcluster       Include the NDB        no                     
                       Cluster table handler                         
-with-openssl=DIR      Include the OpenSSL                           
                       support                                       
-with-openssl-includes Find OpenSSL headers                          
                       in DIR                                        
-with-openssl-libs     Find OpenSSL                                  
                       libraries in DIR                              
-with-other-libc=DIR   Link against libc and                         
                       other standard                                
                       libraries installed                           
                       in the specified                              
                       non-standard location                         
-with-pic              Try to use only        Use both               
                       PIC/non-PIC objects                           
-with-plugin-PLUGIN    Forces the named                              
                       plugin to be linked                           
                       into mysqld statically                        
-with-plugins          Plugins to include in  none                   
                       mysqld                                        
-with-pstack           Use the pstack                                
                       backtrace library                             
-with-pthread          Force use of pthread                          
                       library                                       
-with-row-based-replicationInclude row-based                             
                       replication                                   
-with-server-suffix    Append value to the                           
                       version string                                
-with-ssl=DIR          Include SSL support                           
-with-system-type      Set the system type,                          
                       like "sun-solaris10"                          
-with-tags             Include additional     automatic              
                       configurations                                
-with-tcp-port         Which port to use for  3306                   
                       MySQL services                                
-with-unix-socket-path Where to put the                              
                       unix-domain socket                            
-with-yassl            Include the yaSSL                             
                       support                                       
-with-zlib-dir=no|bundled|DIRProvide MySQL with a                          
                       custom location of                            
                       compression library                           
-without-PACKAGE       Do not use PACKAGE                            
-without-bench         Skip building of the                          
                       benchmark suite                               
-without-debug         Build a production                            
                       version without                               
                       debugging code                                
-without-docs          Skip building of the                          
                       documentation                                 
-without-extra-tools   Skip building                                 
                       utilities in the                              
                       tools directory                               
-without-geometry      Do not build                                  
                       geometry-related parts                        
-without-libedit       Use system libedit                            
                       instead of bundled                            
                       copy                                          
-without-libevent      Do not include                        6.0.4   
                       libevent for                                  
                       thread-pool support                           
-without-man           Skip building of the                          
                       man pages                                     
-without-ndb-binlog    Disable ndb binlog                            
-without-ndb-debug     Disable special ndb                           
                       debug features                                
-without-plugin-PLUGIN Exclude PLUGIN                                
-without-query-cache   Do not build query                            
                       cache                                         
-without-readline      Use system readline                           
                       instead of bundled                            
                       copy                                          
-without-row-based-replicationDon't include                                 
                       row-based replication                         
-without-server        Only build the client                         
-without-uca           Skip building of the                          
                       national Unicode                              
                       collations                                    

Some of the `configure' options available are described here. For
options that may be of use if you have difficulties building MySQL, see
*Note compilation-problems::.

   *  To compile just the MySQL client libraries and client programs
     and not the server, use the `--without-server' option:

          shell> ./configure --without-server

     If you have no C++ compiler, some client programs such as *Note
     `mysql': mysql. cannot be compiled because they require C++.. In
     this case, you can remove the code in `configure' that tests for
     the C++ compiler and then run `./configure' with the
     `--without-server' option.  The compile step should still try to
     build all clients, but you can ignore any warnings about files
     such as `mysql.cc'. (If `make' stops, try `make -k' to tell it to
     continue with the rest of the build even if errors occur.)

   *  If you want to build the embedded MySQL library (`libmysqld.a'),
     use the `--with-embedded-server' option.

   *  If you don't want your log files and database directories located
     under `/usr/local/var', use a `configure' command something like
     one of these:

          shell> ./configure --prefix=/usr/local/mysql
          shell> ./configure --prefix=/usr/local \
                     --localstatedir=/usr/local/mysql/data

     The first command changes the installation prefix so that
     everything is installed under `/usr/local/mysql' rather than the
     default of `/usr/local'. The second command preserves the default
     installation prefix, but overrides the default location for
     database directories (normally `/usr/local/var') and changes it to
     `/usr/local/mysql/data'.

     You can also specify the installation directory and data directory
     locations at server startup time by using the `--basedir' and
     `--datadir' options. These can be given on the command line or in
     an MySQL option file, although it is more common to use an option
     file. See *Note option-files::.

   *  If you are using Unix and you want the MySQL socket file location
     to be somewhere other than the default location (normally in the
     directory `/tmp' or `/var/run'), use a `configure' command like
     this:

          shell> ./configure \
                     --with-unix-socket-path=/usr/local/mysql/tmp/mysql.sock

     The socket file name must be an absolute path name. You can also
     change the location of `mysql.sock' at server startup by using a
     MySQL option file. See *Note problems-with-mysql-sock::.

   *  If you want to compile statically linked programs (for example,
     to make a binary distribution, to get better performance, or to
     work around problems with some Red Hat Linux distributions), run
     `configure' like this:

          shell> ./configure --with-client-ldflags=-all-static \
                     --with-mysqld-ldflags=-all-static

   * If you are using `gcc' and don't have `libg++' or `libstdc++'
     installed, you can tell `configure' to use `gcc' as your C++
     compiler:

          shell> CC=gcc CXX=gcc ./configure

     When you use `gcc' as your C++ compiler, it does not attempt to
     link in `libg++' or `libstdc++'. This may be a good thing to do
     even if you have those libraries installed. Some versions of them
     have caused strange problems for MySQL users in the past.

     The following list indicates some compilers and environment
     variable settings that are commonly used with each one.

        * `gcc' 2.7.2:

               CC=gcc CXX=gcc CXXFLAGS="-O3 -felide-constructors"

        * `gcc' 2.95.2:

               CFLAGS="-O3 -mpentiumpro" CXX=gcc CXXFLAGS="-O3 -mpentiumpro \
               -felide-constructors -fno-exceptions -fno-rtti"

        * `pgcc' 2.90.29 or newer:

               CFLAGS="-O3 -mpentiumpro -mstack-align-double" CXX=gcc \
               CXXFLAGS="-O3 -mpentiumpro -mstack-align-double \
               -felide-constructors -fno-exceptions -fno-rtti"

     In most cases, you can get a reasonably optimized MySQL binary by
     using the options from the preceding list and adding the following
     options to the `configure' line:

          --prefix=/usr/local/mysql --enable-assembler \
          --with-mysqld-ldflags=-all-static

     The full `configure' line would, in other words, be something like
     the following for all recent `gcc' versions:

          CFLAGS="-O3 -mpentiumpro" CXX=gcc CXXFLAGS="-O3 -mpentiumpro \
          -felide-constructors -fno-exceptions -fno-rtti" ./configure \
          --prefix=/usr/local/mysql --enable-assembler \
          --with-mysqld-ldflags=-all-static

     The binaries we provide on the MySQL Web site at
     `http://dev.mysql.com/downloads/' are all compiled with full
     optimization and should be perfect for most users. See *Note
     mysql-binaries::. There are some configuration settings you can
     tweak to build an even faster binary, but these are only for
     advanced users. See *Note compile-and-link-options::.

     If the build fails and produces errors about your compiler or
     linker not being able to create the shared library
     `libmysqlclient.so.N' (where N is a version number), you can work
     around this problem by giving the `--disable-shared' option to
     `configure'. In this case, `configure' does not build a shared
     `libmysqlclient.so.N' library.

   *  By default, MySQL uses the `latin1' (cp1252 West European)
     character set. To change the default set, use the `--with-charset'
     option:

          shell> ./configure --with-charset=CHARSET

     CHARSET may be one of `binary', `armscii8', `ascii', `big5',
     `cp1250', `cp1251', `cp1256', `cp1257', `cp850', `cp852', `cp866',
     `cp932', `dec8', `eucjpms', `euckr', `gb2312', `gbk', `geostd8',
     `greek', `hebrew', `hp8', `keybcs2', `koi8r', `koi8u', `latin1',
     `latin2', `latin5', `latin7', `macce', `macroman', `sjis', `swe7',
     `tis620', `ucs2', `ujis', `utf8', `utf8mb3', `utf16', `utf32'. See
     *Note charset-configuration::. (Additional character sets might be
     available. Check the output from `./configure --help' for the
     current list.)

     The default collation may also be specified. MySQL uses the
     `latin1_swedish_ci' collation by default.  To change this, use the
     `--with-collation' option:

          shell> ./configure --with-collation=COLLATION

     To change both the character set and the collation, use both the
     `--with-charset' and `--with-collation' options.  The collation
     must be a legal collation for the character set. (Use the *Note
     `SHOW COLLATION': show-collation.  statement to determine which
     collations are available for each character set.)

     *Warning*:

     If you change character sets after having created any tables, you
     must run *Note `myisamchk -r -q --set-collation=COLLATION_NAME':
     myisamchk.  _on every `MyISAM' table_. Your indexes may be sorted
     incorrectly otherwise. This can happen if you install MySQL, create
     some tables, and then reconfigure MySQL to use a different
     character set and reinstall it.

     With the `configure' option `--with-extra-charsets=LIST', you can
     define which additional character sets should be compiled into the
     server. LIST is one of the following:

        * A list of character set names separated by spaces

        * `complex' to include all character sets that can't be
          dynamically loaded

        * `all' to include all character sets into the binaries

     Clients that want to convert characters between the server and the
     client should use the `SET NAMES' statement. See *Note
     server-session-variables::, and *Note charset-connection::.

   *  To configure MySQL with debugging code, use the `--with-debug'
     option:

          shell> ./configure --with-debug

     This causes a safe memory allocator to be included that can find
     some errors and that provides output about what is happening. See
     MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

     Using `--with-debug' to configure MySQL with debugging support
     enables you to use the `--debug="d,parser_debug"' option when you
     start the server. This causes the Bison parser that is used to
     process SQL statements to dump a parser trace to the server's
     standard error output.  Typically, this output is written to the
     error log.

   *  To cause the Debug Sync facility to be compiled into the server,
     use the `--enable-debug-sync' option. This facility is used for
     testing and debugging.  When compiled in, Debug Sync is disabled
     by default. To enable it, start mysqld with the
     `--debug-sync-timeout=N' option, where N is a timeout value
     greater than 0. (The default value is 0, which disables Debug
     Sync.) N becomes the default timeout for individual
     synchronization points.

     Debug Sync is also compiled in if you configure with the
     `--with-debug' option (which implies `--enable-debug-sync'),
     unless you also use the `--disable-debug-sync' option.

     For a description of the Debug Sync facility and how to use
     synchronization points, see MySQL Internals: Test Synchronization
     (http://forge.mysql.com/wiki/MySQL_Internals_Test_Synchronization).

     The `--enable-debug-sync' and `--disable-debug-sync' options were
     added in MySQL 6.0.6.

   *  The `--enable-dtrace' option causes support for DTrace probes to
     be included. Use the `--disable-dtrace' to disable DTrace probe
     support.

     The `--enable-dtrace' and `--disable-dtrace' options were added in
     MySQL 6.0.4.

   *  If your client programs are using threads, you must compile a
     thread-safe version of the MySQL client library with the
     `--enable-thread-safe-client' configure option. This creates a
     `libmysqlclient_r' library with which you should link your
     threaded applications. See *Note threaded-clients::.

   *  Some features require that the server be built with compression
     library support, such as the `COMPRESS()' and `UNCOMPRESS()'
     functions, compression of the client/server protocol, and
     compression by *Note `BACKUP DATABASE': backup-database. The
     `--with-zlib-dir=no|bundled|DIR' option provides control for
     compression library support. The value `no' explicitly disables
     compression support. `bundled' causes the `zlib' library bundled
     in the MySQL sources to be used. A DIR path name specifies where
     to find the compression library sources.

   *  It is possible to build MySQL with large table support using the
     `--with-big-tables' option.

     This option causes the variables that store table row counts to be
     declared as `unsigned long long' rather than `unsigned long'. This
     enables tables to hold up to approximately 1.844E+19 ((2^32)^2)
     rows rather than 2^32 (~4.295E+09) rows. Previously it was
     necessary to pass `-DBIG_TABLES' to the compiler manually in order
     to enable this feature.

   *  Run `configure' with the `--disable-grant-options' option to
     cause the `--bootstrap', `--skip-grant-tables', and `--init-file'
     options for *Note `mysqld': mysqld. to be disabled. For Windows,
     the `configure.js' script recognizes the `DISABLE_GRANT_OPTIONS'
     flag, which has the same effect.

   *  As of MySQL 6.0.4, client connections can be managed by a
     fix-size pool of threads rather than allocating one thread per
     connection. Thread pooling is based on the `libevent' library. To
     build a server that includes the thread-pool capability, configure
     MySQL using the `--with-libevent' option. The `--without-libevent'
     option excludes the `libevent' code. For information about
     choosing which thread model the server uses, see *Note
     connection-threads::.

   *  This option allows MySQL Community Server features to be enabled.
     Additional options may be required for individual features, such as
     `--enable-profiling' to enable statement profiling. This option
     was added in MySQL 6.0.5. It is enabled by default; to disable it,
     use `--disable-community-features'.

   *  When given with `--enable-community-features', the
     `--enable-profiling' option enables the statement profiling
     capability exposed by the *Note `SHOW PROFILE': show-profile. and
     *Note `SHOW PROFILES': show-profiles. statements.  (See *Note
     show-profiles::.) This option was added in MySQL 6.0.5. It is
     enabled by default; to disable it, use `--disable-profiling'.

   * See *Note operating-system-specific-notes::, for options that
     pertain to particular operating systems.

   * See *Note secure-using-ssl::, for options that pertain to
     configuring MySQL to support secure (encrypted) connections.

   *  Several `configure' options apply to plugin selection and
     building:

          --with-plugins=PLUGIN[,PLUGIN]...
          --with-plugins=GROUP
          --with-plugin-PLUGIN
          --without-plugin-PLUGIN

     PLUGIN is an individual plugin name such as `csv' or `archive'.

     As shorthand, GROUP is a configuration group name such as `none'
     (select no plugins) or `all' (select all plugins).

     You can build a plugin as static (compiled into the server) or
     dynamic (built as a dynamic library that must be installed using
     the *Note `INSTALL PLUGIN': install-plugin. statement before it
     can be used). Some plugins might not support static or dynamic
     build.

     `configure --help' shows the following information pertaining to
     plugins:

        * The plugin-related options

        * The names of all available plugins

        * For each plugin, a description of its purpose, which build
          types it supports (static or dynamic), and which plugin
          groups it is a part of.

     `--with-plugins' can take a list of one or more plugin names
     separated by commas, or a plugin group name. The named plugins are
     configured to be built as static plugins.

     `--with-plugin-PLUGIN' configures the given plugin to be built as
     a static plugin.

     `--without-plugin-PLUGIN' disables the given plugin from being
     built.

     If a plugin is named both with a `--with' and `--without' option,
     the result is undefined.

     For any plugin that is not explicitly selected or disabled, it is
     selected to be built dynamically if it supports dynamic build, and
     not built if it does not support dynamic build. (Thus, in the case
     that no plugin options are given, all plugins that support dynamic
     build are selected to be built as dynamic plugins. Plugins that do
     not support dynamic build are not built.)


File: manual.info,  Node: installing-source-tree,  Next: compilation-problems,  Prev: configure-options,  Up: installing-source

2.9.3 Installing from the Development Source Tree
-------------------------------------------------

*Caution*:

You should read this section only if you are interested in helping us
test our new code. If you just want to get MySQL up and running on your
system, you should use a standard release distribution (either a binary
or source distribution).

To obtain the most recent development source tree, you first need to
download and install Bazaar. You can obtain Bazaar from the Bazaar VCS
Website (http://bazaar-vcs.org). Bazaar is supported by any platform
that supports Python, and is therefore compatible with any Linux, Unix,
Windows or Mac OS X host. Instructions for downloading and installing
Bazaar on the different platforms are available on the Bazaar website.

All MySQL projects are hosted on Launchpad (http://launchpad.net/).
MySQL projects, including MySQL server, MySQL Workbench and others are
available from the Sun/MySQL Engineering (http://launchpad.net/~mysql)
page. For the repositories related only to MySQL server, see the MySQL
Server (http://launchpad.net/mysql-server) page.

To build under Unix/Linux, you must have the following tools installed:

   * GNU `make', available from `http://www.gnu.org/software/make/'.
     Although some platforms come with their own `make'
     implementations, it is highly recommended that you use GNU `make'.
     It may already be available on your system as `gmake'.

   * `autoconf' 2.58 (or newer), available from
     `http://www.gnu.org/software/autoconf/'.

   * `automake' 1.8.1, available from
     `http://www.gnu.org/software/automake/'.

   * `libtool' 1.5, available from
     `http://www.gnu.org/software/libtool/'.

   * `m4', available from `http://www.gnu.org/software/m4/'.

   * `bison', available from `http://www.gnu.org/software/bison/'. You
     should use the latest version of bison where possible.  Version
     1.75 and version 2.1 are known to work. There have been reported
     problems with `bison' 1.875.  If you experience problems, upgrade
     to a later, rather than earlier, version. Versions of `bison' older
     than 1.75 may report this error:

          sql_yacc.yy:#####: fatal error: maximum table size (32767) exceeded

     The maximum table size is not actually exceeded; the error is
     caused by bugs in older versions of `bison'.

To build under Windows you will need a copy of Microsoft Visual C++
2005 Express Edition, Visual Studio .Net 2003 (7.1), or Visual Studio
2005 (8.0) compiler system.

Once you have the necessary tools installed, you first need to create a
local branch of the MySQL source code on your machine:

  1. To obtain a copy of the MySQL source code, you must create a new
     Bazaar branch. If you do not already have a Bazaar repository
     directory set up, you need to initialize a new directory:

          shell> mkdir mysql-server
          shell> bzr init-repo --trees mysql-server

     Once you have an initialized directory, you can `branch' from the
     public MySQL server repositories. To create a branch of a specific
     version:

          shell> cd mysql-server
          shell> bzr branch lp:mysql-server/6.0 mysql-6.0

     The initial download will take some time to complete, depending on
     the speed of your connection. Please be patient. Once you have
     downloaded the first tree, additional trees should take
     significantly less time to download.

     When building from the Bazaar branch, you may want to create a
     copy of your active branch so that you can make configuration and
     other changes without affecting the original branch contents. You
     can achieve this by branching from the original branch:

          shell> bzr branch mysql-6.0 mysql-6.0-build

Once you have the local branch, you can start to build MySQL server
from the source code. On Windows, the build process is different from
Unix/Linux. To continue building MySQL on Windows, see *Note
windows-source-build::.

On Unix/Linux you need to use the `autoconf' system to create the
`configure' script so that you can configure the build environment
before building.

  1. The following example shows the typical commands required to
     configure a source tree. The first `cd' command changes location
     into the top-level directory of the tree; replace `mysql-6.0' with
     the appropriate directory name.

          shell> cd mysql-6.0
          shell> autoreconf --force --install
          shell> ./configure  # Add your favorite options here
          shell> make

     Or you can use `BUILD/autorun.sh' as a shortcut for the following
     sequence of commands:

          shell> aclocal; autoheader
          shell> libtoolize --automake --force
          shell> automake --force --add-missing; autoconf

     The command line that changes directory into the
     `storage/innobase' directory is used to configure the `InnoDB'
     storage engine. You can omit this lines if you do not require
     `InnoDB' support.

     If you get some strange errors during this stage, verify that you
     have the correct version of the `libtool' installed.

     A collection of our standard configuration scripts is located in
     the `BUILD/' subdirectory. For example, you may find it more
     convenient to use the `BUILD/compile-pentium-debug' script than
     the preceding set of shell commands. To compile on a different
     architecture, modify the script by removing flags that are
     Pentium-specific, or use another script that may be more
     appropriate. These scripts are provided on an `as-is' basis. They
     are not officially maintained and their contents may change from
     release to release.

  2. When the build is done, run `make install'.  Be careful with this
     on a production machine; the command may overwrite your live
     release installation. If you have another installation of MySQL,
     we recommend that you run `./configure' with different values for
     the `--prefix', `--with-tcp-port', and `--with-unix-socket-path'
     options than those used for your production server.

  3. Play hard with your new installation and try to make the new
     features crash. Start by running `make test'. See *Note
     mysql-test-suite::.

  4. If you have gotten to the `make' stage, but the distribution does
     not compile, please enter the problem into our bugs database using
     the instructions given in *Note bug-reports::. If you have
     installed the latest versions of the required GNU tools, and they
     crash trying to process our configuration files, please report
     that also. However, if you execute `aclocal' and get a `command not
     found' error or a similar problem, do not report it. Instead, make
     sure that all the necessary tools are installed and that your
     `PATH' variable is set correctly so that your shell can find them.

  5. After initially copying the repository with `bzr' to obtain the
     source tree, you should use `pull' option to periodically update
     your local copy. To do this any time after you have set up the
     repository, use this command:

          shell> bzr pull

  6. You can examine the changeset comments for the tree by using the
     `log' option to `bzr':

          shell> bzr log

     You can also browse changesets, comments, and source code online.
     To browse this information for MySQL 6.0, go to
     `http://launchpad.net/mysql-server/'.

     If you see diffs or code that you have a question about, do not
     hesitate to send email to the MySQL `internals' mailing list. See
     *Note mailing-lists::. Also, if you think you have a better idea
     on how to do something, send an email message to the list with a
     patch.


File: manual.info,  Node: compilation-problems,  Next: mit-pthreads,  Prev: installing-source-tree,  Up: installing-source

2.9.4 Dealing with Problems Compiling MySQL
-------------------------------------------

All MySQL programs compile cleanly for us with no warnings on Solaris
or Linux using `gcc'. On other systems, warnings may occur due to
differences in system include files.  See *Note mit-pthreads::, for
warnings that may occur when using MIT-pthreads. For other problems,
check the following list.

The solution to many problems involves reconfiguring. If you do need to
reconfigure, take note of the following:

   * If `configure' is run after it has previously been run, it may use
     information that was gathered during its previous invocation. This
     information is stored in `config.cache'. When `configure' starts
     up, it looks for that file and reads its contents if it exists, on
     the assumption that the information is still correct. That
     assumption is invalid when you reconfigure.

   * Each time you run `configure', you must run `make' again to
     recompile. However, you may want to remove old object files from
     previous builds first because they were compiled using different
     configuration options.

To prevent old configuration information or object files from being
used, run these commands before re-running `configure':

     shell> rm config.cache
     shell> make clean

Alternatively, you can run `make distclean'.

The following list describes some of the problems when compiling MySQL
that have been found to occur most often:

   *  If you get errors such as the ones shown here when compiling
     `sql_yacc.cc', you probably have run out of memory or swap space:

          Internal compiler error: program cc1plus got fatal signal 11
          Out of virtual memory
          Virtual memory exhausted

     The problem is that `gcc' requires a huge amount of memory to
     compile `sql_yacc.cc' with inline functions. Try running
     `configure' with the `--with-low-memory' option:

          shell> ./configure --with-low-memory

     This option causes `-fno-inline' to be added to the compile line
     if you are using `gcc' and `-O0' if you are using something else.
     You should try the `--with-low-memory' option even if you have so
     much memory and swap space that you think you can't possibly have
     run out. This problem has been observed to occur even on systems
     with generous hardware configurations, and the `--with-low-memory'
     option usually fixes it.

   * By default, `configure' picks `c++' as the compiler name and GNU
     `c++' links with `-lg++'. If you are using `gcc', that behavior can
     cause problems during configuration such as this:

          configure: error: installation or configuration problem:
          C++ compiler cannot create executables.

     You might also observe problems during compilation related to
     `g++', `libg++', or `libstdc++'.

     One cause of these problems is that you may not have `g++', or you
     may have `g++' but not `libg++', or `libstdc++'. Take a look at the
     `config.log' file. It should contain the exact reason why your C++
     compiler didn't work. To work around these problems, you can use
     `gcc' as your C++ compiler. Try setting the environment variable
     `CXX' to `"gcc -O3"'. For example:

          shell> CXX="gcc -O3" ./configure

     This works because `gcc' compiles C++ source files as well as
     `g++' does, but does not link in `libg++' or `libstdc++' by
     default.

     Another way to fix these problems is to install `g++', `libg++',
     and `libstdc++'. However, we recommend that you not use `libg++' or
     `libstdc++' with MySQL because this only increases the binary size
     of *Note `mysqld': mysqld.  without providing any benefits. Some
     versions of these libraries have also caused strange problems for
     MySQL users in the past.

   * If your compile fails with errors such as any of the following,
     you must upgrade your version of `make' to GNU `make':

          making all in mit-pthreads
          make: Fatal error in reader: Makefile, line 18:
          Badly formed macro assignment

     Or:

          make: file `Makefile' line 18: Must be a separator (:

     Or:

          pthread.h: No such file or directory

     Solaris and FreeBSD are known to have troublesome `make' programs.

     GNU `make' 3.75 is known to work.

   * If you want to define flags to be used by your C or C++ compilers,
     do so by adding the flags to the `CFLAGS' and `CXXFLAGS'
     environment variables. You can also specify the compiler names
     this way using `CC' and `CXX'. For example:

          shell> CC=gcc
          shell> CFLAGS=-O3
          shell> CXX=gcc
          shell> CXXFLAGS=-O3
          shell> export CC CFLAGS CXX CXXFLAGS

     See *Note mysql-binaries::, for a list of flag definitions that
     have been found to be useful on various systems.

   * If you get errors such as those shown here when compiling *Note
     `mysqld': mysqld, `configure' did not correctly detect the type of
     the last argument to `accept()', `getsockname()', or
     `getpeername()':

          cxx: Error: mysqld.cc, line 645: In this statement, the referenced
               type of the pointer value ''length'' is ''unsigned long'',
               which is not compatible with ''int''.
          new_sock = accept(sock, (struct sockaddr *)&cAddr, &length);

     To fix this, edit the `config.h' file (which is generated by
     `configure'). Look for these lines:

          /* Define as the base type of the last arg to accept */
          #define SOCKET_SIZE_TYPE XXX

     Change `XXX' to `size_t' or `int', depending on your operating
     system. (You must do this each time you run `configure' because
     `configure' regenerates `config.h'.)

   * The `sql_yacc.cc' file is generated from `sql_yacc.yy'. Normally,
     the build process does not need to create `sql_yacc.cc' because
     MySQL comes with a pre-generated copy. However, if you do need to
     re-create it, you might encounter this error:

          "sql_yacc.yy", line XXX fatal: default action causes potential...

     This is a sign that your version of `yacc' is deficient. You
     probably need to install `bison' (the GNU version of `yacc') and
     use that instead.

   * On Debian Linux 3.0, you need to install `gawk' instead of the
     default `mawk'.

   * If you need to debug *Note `mysqld': mysqld. or a MySQL client,
     run `configure' with the `--with-debug' option, and then recompile
     and link your clients with the new client library. See MySQL
     Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * If you get a compilation error on Linux (for example, SuSE Linux
     8.1 or Red Hat Linux 7.3) similar to the following one, you
     probably do not have `g++' installed:

          libmysql.c:1329: warning: passing arg 5 of `gethostbyname_r' from
          incompatible pointer type
          libmysql.c:1329: too few arguments to function `gethostbyname_r'
          libmysql.c:1329: warning: assignment makes pointer from integer
          without a cast
          make[2]: *** [libmysql.lo] Error 1

     By default, the `configure' script attempts to determine the
     correct number of arguments by using `g++' (the GNU C++ compiler).
     This test yields incorrect results if `g++' is not installed.
     There are two ways to work around this problem:

        * Make sure that the GNU C++ `g++' is installed. On some Linux
          distributions, the required package is called `gpp'; on
          others, it is named `gcc-c++'.

        * Use `gcc' as your C++ compiler by setting the `CXX'
          environment variable to `gcc':

               export CXX="gcc"

     You must run `configure' again after making either of those
     changes.


File: manual.info,  Node: mit-pthreads,  Next: windows-source-build,  Prev: compilation-problems,  Up: installing-source

2.9.5 MIT-pthreads Notes
------------------------

This section describes some of the issues involved in using
MIT-pthreads.

On Linux, you should _not_ use MIT-pthreads.  Use the installed
LinuxThreads implementation instead. See *Note linux::.

If your system does not provide native thread support, you should build
MySQL using the MIT-pthreads package. This includes older FreeBSD
systems, SunOS 4.x, Solaris 2.4 and earlier, and some others. See *Note
which-os::.

MIT-pthreads is not part of the MySQL 6.0 source distribution. If you
require this package, you need to download it separately from
`http://dev.mysql.com/Downloads/Contrib/pthreads-1_60_beta6-mysql.tar.gz'

After downloading, extract this source archive into the top level of
the MySQL source directory. It creates a new subdirectory named
`mit-pthreads'.

   * On most systems, you can force MIT-pthreads to be used by running
     `configure' with the `--with-mit-threads' option:

          shell> ./configure --with-mit-threads

     Building in a non-source directory is not supported when using
     MIT-pthreads because we want to minimize our changes to this code.

   * The checks that determine whether to use MIT-pthreads occur only
     during the part of the configuration process that deals with the
     server code. If you have configured the distribution using
     `--without-server' to build only the client code, clients do not
     know whether MIT-pthreads is being used and use Unix socket file
     connections by default. Because Unix socket files do not work
     under MIT-pthreads on some platforms, this means you need to use
     `-h' or `--host' with a value other than `localhost' when you run
     client programs.

   * When MySQL is compiled using MIT-pthreads, system locking is
     disabled by default for performance reasons. You can tell the
     server to use system locking with the `--external-locking' option.
     This is needed only if you want to be able to run two MySQL
     servers against the same data files, but that is not recommended,
     anyway.

   * Sometimes the pthread `bind()' command fails to bind to a socket
     without any error message (at least on Solaris). The result is
     that all connections to the server fail. For example:

          shell> mysqladmin version
          mysqladmin: connect to server at '' failed;
          error: 'Can't connect to mysql server on localhost (146)'

     The solution to this problem is to kill the *Note `mysqld':
     mysqld. server and restart it. This has happened to us only when
     we have forcibly stopped the server and restarted it immediately.

   * With MIT-pthreads, the `sleep()' system call isn't interruptible
     with `SIGINT' (break). This is noticeable only when you run *Note
     `mysqladmin --sleep': mysqladmin. You must wait for the `sleep()'
     call to terminate before the interrupt is served and the process
     stops.

   * When linking, you might receive warning messages like these (at
     least on Solaris); they can be ignored:

          ld: warning: symbol `_iob' has differing sizes:
              (file /my/local/pthreads/lib/libpthread.a(findfp.o) value=0x4;
          file /usr/lib/libc.so value=0x140);
              /my/local/pthreads/lib/libpthread.a(findfp.o) definition taken
          ld: warning: symbol `__iob' has differing sizes:
              (file /my/local/pthreads/lib/libpthread.a(findfp.o) value=0x4;
          file /usr/lib/libc.so value=0x140);
              /my/local/pthreads/lib/libpthread.a(findfp.o) definition taken

   * Some other warnings also can be ignored:

          implicit declaration of function `int strtoll(...)'
          implicit declaration of function `int strtoul(...)'

   * We have not been able to make `readline' work with MIT-pthreads.
     (This is not necessary, but may be of interest to some.)


File: manual.info,  Node: windows-source-build,  Next: windows-client-compiling,  Prev: mit-pthreads,  Up: installing-source

2.9.6 Installing MySQL from Source on Windows
---------------------------------------------

* Menu:

* windows-source-build-cmake::   Building MySQL from Source Using CMake and Visual Studio

These instructions describe how to build binaries from source for MySQL
6.0 on Windows. Instructions are provided for building binaries from a
standard source distribution or from the Bazaar tree that contains the
latest development source.

*Note*:

The instructions here are strictly for users who want to test MySQL on
Microsoft Windows from the latest source distribution or from the
Bazaar tree. For production use, we do not advise using a MySQL server
built by yourself from source. Normally, it is best to use precompiled
binary distributions of MySQL that are built specifically for optimal
performance on Windows by Sun Microsystems, Inc. Instructions for
installing binary distributions are available in *Note
windows-installation::.

To build MySQL on Windows from source, you must satisfy the following
system, compiler, and resource requirements:

   * Windows 2000, Windows XP, or newer version.

     Windows Vista is supported when using Visual Studio 2005 provided
     you have installed the following updates:

        * Microsoft Visual Studio 2005 Professional Edition - ENU
          Service Pack 1 (KB926601)
          (http://support.microsoft.com/?kbid=926601)

        * Security Update for Microsoft Visual Studio 2005 Professional
          Edition - ENU (KB937061)
          (http://support.microsoft.com/?kbid=937061)

        * Update for Microsoft Visual Studio 2005 Professional Edition
          - ENU (KB932232) (http://support.microsoft.com/?kbid=932232)

   * CMake, which can be downloaded from `http://www.cmake.org'. After
     installing, modify your path to include the `cmake' binary.

   * Microsoft Visual C++ 2005 Express Edition, Visual Studio .Net 2003
     (7.1), or Visual Studio 2005 (8.0) compiler system.

   * If you are using Visual C++ 2005 Express Edition, you must also
     install an appropriate Platform SDK. More information and links to
     downloads for various Windows platforms is available from
     `http://www.microsoft.com/downloads/details.aspx?familyid=0baf2b35-c656-4969-ace8-e4c0c0716adb'.

   * If you are compiling from a Bazaar tree or making changes to the
     parser, you need `bison' for Windows, which can be downloaded from
     `http://gnuwin32.sourceforge.net/packages/bison.htm'.  Download
     the package labeled `Complete package, excluding sources'. After
     installing the package, modify your path to include the `bison'
     binary and ensure that this binary is accessible from Visual
     Studio.

   * Cygwin might be necessary if you want to run the test script or
     package the compiled binaries and support files into a Zip
     archive. (Cygwin is needed only to test or package the
     distribution, not to build it.) Cygwin is available from
     `http://cygwin.com'.

   * 3GB to 5GB of disk space.

The exact system requirements can be found here:
`http://msdn.microsoft.com/vstudio/Previous/2003/sysreqs/default.aspx'
and `http://msdn.microsoft.com/vstudio/products/sysreqs/default.aspx'

You also need a MySQL source distribution for Windows, which can be
obtained two ways:

   * Obtain a source distribution packaged by Sun Microsystems, Inc.
     These are available from `http://dev.mysql.com/downloads/'.

   * Package a source distribution yourself from the latest Bazaar
     developer source tree. For instructions on pulling the latest
     source files, see *Note installing-source-tree::.

If you find something not working as expected, or you have suggestions
about ways to improve the current build process on Windows, please send
a message to the `win32' mailing list. See *Note mailing-lists::.


File: manual.info,  Node: windows-source-build-cmake,  Prev: windows-source-build,  Up: windows-source-build

2.9.6.1 Building MySQL from Source Using CMake and Visual Studio
................................................................

You can build MySQL on Windows by using a combination of `cmake' and
Microsoft Visual Studio .NET 2003 (7.1), Microsoft Visual Studio 2005
(8.0) or Microsoft Visual C++ 2005 Express Edition. You must have the
appropriate Microsoft Platform SDK installed.

*Note*:

To compile from the source code on Windows you must use the standard
source distribution (for example, `mysql-5.0.45.tar.gz').  You build
from the same distribution as used to build MySQL on Unix, Linux and
other platforms. Do _not_ use the Windows Source distributions as they
do not contain the necessary configuration script and other files.

Follow this procedure to build MySQL:

  1. If you are installing from a packaged source distribution, create
     a work directory (for example, `C:\workdir'), and unpack the source
     distribution there using `WinZip' or another Windows tool that can
     read `.zip' files. This directory is the work directory in the
     following instructions.

  2. If you are installing from a Bazaar tree, the root directory of
     that tree is the work directory in the following instructions.

  3. Using a command shell, navigate to the work directory and run the
     following command:

          C:\workdir>win\configure.js OPTIONS

     If you have associated the `.js' file extension with an
     application such as a text editor, then you may need to use the
     following command to force `configure.js' to be executed as a
     script:

          C:\workdir>cscript win\configure.js OPTIONS

     These options are available for `configure.js':

        * `WITH_INNOBASE_STORAGE_ENGINE': Enable the `InnoDB' storage
          engine.

        * `WITH_PARTITION_STORAGE_ENGINE': Enable user-defined
          partitioning.

        * `WITH_ARCHIVE_STORAGE_ENGINE': Enable the `ARCHIVE' storage
          engine.

        * `WITH_BLACKHOLE_STORAGE_ENGINE': Enable the `BLACKHOLE'
          storage engine.

        * `WITH_EXAMPLE_STORAGE_ENGINE': Enable the `EXAMPLE' storage
          engine.

        * `WITH_FEDERATED_STORAGE_ENGINE': Enable the `FEDERATED'
          storage engine.

        * `MYSQL_SERVER_SUFFIX=SUFFIX': Server suffix, default none.

        * `COMPILATION_COMMENT=COMMENT': Server comment, default
          "Source distribution".

        * `MYSQL_TCP_PORT=PORT': Server port, default 3306.

        * `DISABLE_GRANT_OPTIONS': Disables the `--bootstrap',
          `--skip-grant-tables', and `--init-file' options for *Note
          `mysqld': mysqld.

     For example (type the command on one line):

          C:\workdir>win\configure.js WITH_INNOBASE_STORAGE_ENGINE
                       WITH_PARTITION_STORAGE_ENGINE MYSQL_SERVER_SUFFIX=-pro

  4. From the work directory, execute the `win\build-vs8.bat' or
     `win\build-vs71.bat' file, depending on the version of Visual
     Studio you have installed. The script invokes CMake, which
     generates the `mysql.sln' solution file.

     You can also use `win\build-vs8_x64.bat' to build the 64-bit
     version of MySQL. However, you cannot build the 64-bit version
     with Visual Studio Express Edition. You must use Visual Studio
     2005 (8.0) or higher.

  5. From the work directory, open the generated `mysql.sln' file with
     Visual Studio and select the proper configuration using the
     `Configuration' menu. The menu provides `Debug', `Release',
     `RelwithDebInfo', `MinRelInfo' options. Then select `Solution' >
     `Build' to build the solution.

     Remember the configuration that you use in this step. It is
     important later when you run the test script because that script
     needs to know which configuration you used.

  6. Test the server. The server built using the preceding instructions
     expects that the MySQL base directory and data directory are
     `C:\mysql' and `C:\mysql\data' by default. If you want to test
     your server using the source tree root directory and its data
     directory as the base directory and data directory, you need to
     tell the server their path names.  You can either do this on the
     command line with the `--basedir' and `--datadir' options, or by
     placing appropriate options in an option file. (See *Note
     option-files::.) If you have an existing data directory elsewhere
     that you want to use, you can specify its path name instead.

     When the server is running in standalone fashion or as a service
     based on your configuration, try to connect to it from the *Note
     `mysql': mysql. interactive command-line utility.

     You can also run the standard test script, `mysql-test-run.pl'.
     This script is written in Perl, so you'll need either Cygwin or
     ActiveState Perl to run it. You may also need to install the
     modules required by the script. To run the test script, change
     location into the `mysql-test' directory under the work directory,
     set the `MTR_VS_CONFIG' environment variable to the configuration
     you selected earlier (or use the `--vs-config' option), and invoke
     `mysql-test-run.pl'.  For example (using Cygwin and the `bash'
     shell):

          shell> `cd mysql-test'
          shell> `export MTS_VS_CONFIG=debug'
          shell> `./mysql-test-run.pl --force --timer'
          shell> `./mysql-test-run.pl --force --timer --ps-protocol'

When you are satisfied that the programs you have built are working
correctly, stop the server. Now you can install the distribution. One
way to do this is to use the *Note `make_win_bin_dist':
make-win-bin-dist. script in the `scripts' directory of the MySQL source
distribution (see *Note make-win-bin-dist::). This is a shell script,
so you must have Cygwin installed if you want to use it. It creates a
Zip archive of the built executables and support files that you can
unpack in the location at which you want to install MySQL.

It is also possible to install MySQL by copying directories and files
directly:

  1. Create the directories where you want to install MySQL.  For
     example, to install into `C:\mysql', use these commands:

          C:\> mkdir C:\mysql
          C:\> mkdir C:\mysql\bin
          C:\> mkdir C:\mysql\data
          C:\> mkdir C:\mysql\share
          C:\> mkdir C:\mysql\scripts

     If you want to compile other clients and link them to MySQL, you
     should also create several additional directories:

          C:\> mkdir C:\mysql\include
          C:\> mkdir C:\mysql\lib
          C:\> mkdir C:\mysql\lib\debug
          C:\> mkdir C:\mysql\lib\opt

     If you want to benchmark MySQL, create this directory:

          C:\> mkdir C:\mysql\sql-bench

     Benchmarking requires Perl support. See *Note perl-support::.

  2. From the work directory, copy into the `C:\mysql' directory the
     following directories:

          C:\> cd \workdir
          C:\workdir> copy client_release\*.exe C:\mysql\bin
          C:\workdir> copy client_debug\mysqld.exe C:\mysql\bin\mysqld-debug.exe
          C:\workdir> xcopy scripts\*.* C:\mysql\scripts /E
          C:\workdir> xcopy share\*.* C:\mysql\share /E

     If you want to compile other clients and link them to MySQL, you
     should also copy several libraries and header files:

          C:\workdir> copy lib_debug\mysqlclient.lib C:\mysql\lib\debug
          C:\workdir> copy lib_debug\libmysql.* C:\mysql\lib\debug
          C:\workdir> copy lib_debug\zlib.* C:\mysql\lib\debug
          C:\workdir> copy lib_release\mysqlclient.lib C:\mysql\lib\opt
          C:\workdir> copy lib_release\libmysql.* C:\mysql\lib\opt
          C:\workdir> copy lib_release\zlib.* C:\mysql\lib\opt
          C:\workdir> copy include\*.h C:\mysql\include
          C:\workdir> copy libmysql\libmysql.def C:\mysql\include

     If you want to benchmark MySQL, you should also do this:

          C:\workdir> xcopy sql-bench\*.* C:\mysql\bench /E

After installation, set up and start the server in the same way as for
binary Windows distributions. See *Note windows-installation::.


File: manual.info,  Node: windows-client-compiling,  Prev: windows-source-build,  Up: installing-source

2.9.7 Compiling MySQL Clients on Windows
----------------------------------------

In your source files, you should include `my_global.h' before `mysql.h':

     #include <my_global.h>
     #include <mysql.h>

`my_global.h' includes any other files needed for Windows compatibility
(such as `windows.h') if you compile your program on Windows.

You can either link your code with the dynamic `libmysql.lib' library,
which is just a wrapper to load in `libmysql.dll' on demand, or link
with the static `mysqlclient.lib' library.

The MySQL client libraries are compiled as threaded libraries, so you
should also compile your code to be multi-threaded.


File: manual.info,  Node: post-installation,  Next: upgrade-downgrade,  Prev: installing-source,  Up: installing

2.10 Post-Installation Setup and Testing
========================================

* Menu:

* windows-post-installation::    Windows Post-Installation Procedures
* unix-post-installation::       Unix Post-Installation Procedures
* default-privileges::           Securing the Initial MySQL Accounts

After installing MySQL, there are some issues that you should address.
For example, on Unix, you should initialize the data directory and
create the MySQL grant tables. On all platforms, an important security
concern is that the initial accounts in the grant tables have no
passwords. You should assign passwords to prevent unauthorized access
to the MySQL server. Optionally, you can create time zone tables to
enable recognition of named time zones.

The following sections include post-installation procedures that are
specific to Windows systems and to Unix systems. Another section, *Note
starting-server::, applies to all platforms; it describes what to do if
you have trouble getting the server to start. *Note
default-privileges::, also applies to all platforms. You should follow
its instructions to make sure that you have properly protected your
MySQL accounts by assigning passwords to them.

When you are ready to create additional user accounts, you can find
information on the MySQL access control system and account management
in *Note privilege-system::, and *Note user-account-management::.


File: manual.info,  Node: windows-post-installation,  Next: unix-post-installation,  Prev: post-installation,  Up: post-installation

2.10.1 Windows Post-Installation Procedures
-------------------------------------------

On Windows, the data directory and the grant tables do not have to be
created. MySQL Windows distributions include the grant tables with a
set of preinitialized accounts in the `mysql' database under the data
directory. It is unnecessary to run the *Note `mysql_install_db':
mysql-install-db.  script that is used on Unix. Regarding passwords, if
you installed MySQL using the Windows Installation Wizard, you may have
already assigned passwords to the accounts. (See *Note
windows-install-wizard::.) Otherwise, use the password-assignment
procedure given in *Note default-privileges::.

Before setting up passwords, you might want to try running some client
programs to make sure that you can connect to the server and that it is
operating properly. Make sure that the server is running (see *Note
windows-server-first-start::), and then issue the following commands to
verify that you can retrieve information from the server. The output
should be similar to what is shown here:

     C:\> C:\mysql\bin\mysqlshow
     +--------------------+
     |     Databases      |
     +--------------------+
     | information_schema |
     | mysql              |
     | test               |
     +--------------------+

     C:\> C:\mysql\bin\mysqlshow mysql
     Database: mysql
     +---------------------------+
     |          Tables           |
     +---------------------------+
     | columns_priv              |
     | db                        |
     | event                     |
     | func                      |
     | general_log               |
     | help_category             |
     | help_keyword              |
     | help_relation             |
     | help_topic                |
     | host                      |
     | plugin                    |
     | proc                      |
     | procs_priv                |
     | servers                   |
     | slow_log                  |
     | tables_priv               |
     | time_zone                 |
     | time_zone_leap_second     |
     | time_zone_name            |
     | time_zone_transition      |
     | time_zone_transition_type |
     | user                      |
     +---------------------------+

     C:\> C:\mysql\bin\mysql -e "SELECT Host,Db,User FROM db" mysql
     +------+-------+------+
     | host | db    | user |
     +------+-------+------+
     | %    | test% |      |
     +------+-------+------+

You may need to specify a different directory from the one shown; if
you used the Windows Installation Wizard, then the default directory is
`C:\Program Files\MySQL\MySQL Server 6.0', and the *Note `mysql':
mysql. and *Note `mysqlshow': mysqlshow. client programs are in
`C:\Program Files\MySQL\MySQL Server 6.0\bin'. See *Note
windows-install-wizard::, for more information.

If you have already secured the initial MySQL accounts, you may need to
use the `-u' and `-p' options to supply a user name and password to the
*Note `mysqlshow': mysqlshow. and *Note `mysql': mysql. client
programs; otherwise the programs may fail with an error, or you may not
be able to view all databases. For example, if you have assigned the
password `secretpass' to the MySQL `root' account, then you can invoke
*Note `mysqlshow': mysqlshow. and *Note `mysql': mysql. as shown here:

     C:\> C:\mysql\bin\mysqlshow -uroot -psecretpass
     +--------------------+
     |     Databases      |
     +--------------------+
     | information_schema |
     | mysql              |
     | test               |
     +--------------------+

     C:\> C:\mysql\bin\mysqlshow -uroot -psecretpass mysql
     Database: mysql
     +---------------------------+
     |          Tables           |
     +---------------------------+
     | columns_priv              |
     | db                        |
     | event                     |
     | func                      |
     | general_log               |
     | help_category             |
     | help_keyword              |
     | help_relation             |
     | help_topic                |
     | host                      |
     | plugin                    |
     | proc                      |
     | procs_priv                |
     | servers                   |
     | slow_log                  |
     | tables_priv               |
     | time_zone                 |
     | time_zone_leap_second     |
     | time_zone_name            |
     | time_zone_transition      |
     | time_zone_transition_type |
     | user                      |
     +---------------------------+

     C:\> C:\mysql\bin\mysql -uroot -psecretpass -e "SELECT Host,Db,User FROM db" mysql
     +------+-------+------+
     | host | db    | user |
     +------+-------+------+
     | %    | test% |      |
     +------+-------+------+

For more information about these programs, see *Note mysqlshow::, and
*Note mysql::.

If you are running a version of Windows that supports services and you
want the MySQL server to run automatically when Windows starts, see
*Note windows-start-service::.


File: manual.info,  Node: unix-post-installation,  Next: default-privileges,  Prev: windows-post-installation,  Up: post-installation

2.10.2 Unix Post-Installation Procedures
----------------------------------------

* Menu:

* mysql-install-db-problems::    Problems Running `mysql_install_db'
* automatic-start::              Starting and Stopping MySQL Automatically
* starting-server::              Starting and Troubleshooting the MySQL Server

After installing MySQL on Unix, you need to initialize the grant
tables, start the server, and make sure that the server works
satisfactorily. You may also wish to arrange for the server to be
started and stopped automatically when your system starts and stops.
You should also assign passwords to the accounts in the grant tables.

On Unix, the grant tables are set up by the *Note `mysql_install_db':
mysql-install-db. program. For some installation methods, this program
is run for you automatically:

   * If you install MySQL on Linux using RPM distributions, the server
     RPM runs *Note `mysql_install_db': mysql-install-db.

   * If you install MySQL on Mac OS X using a PKG distribution, the
     installer runs *Note `mysql_install_db': mysql-install-db.

Otherwise, you'll need to run *Note `mysql_install_db':
mysql-install-db. yourself.

The following procedure describes how to initialize the grant tables
(if that has not previously been done) and then start the server. It
also suggests some commands that you can use to test whether the server
is accessible and working properly. For information about starting and
stopping the server automatically, see *Note automatic-start::.

After you complete the procedure and have the server running, you
should assign passwords to the accounts created by *Note
`mysql_install_db': mysql-install-db. Instructions for doing so are
given in *Note default-privileges::.

In the examples shown here, the server runs under the user ID of the
`mysql' login account. This assumes that such an account exists. Either
create the account if it does not exist, or substitute the name of a
different existing login account that you plan to use for running the
server.

  1. Change location into the top-level directory of your MySQL
     installation, represented here by BASEDIR:

          shell> cd BASEDIR

     BASEDIR is likely to be something like `/usr/local/mysql' or
     `/usr/local'. The following steps assume that you are located in
     this directory.

  2. If necessary, run the *Note `mysql_install_db': mysql-install-db.
     program to set up the initial MySQL grant tables containing the
     privileges that determine how users are allowed to connect to the
     server. You'll need to do this if you used a distribution type for
     which the installation procedure doesn't run the program for you.

     Typically, *Note `mysql_install_db': mysql-install-db. needs to be
     run only the first time you install MySQL, so you can skip this
     step if you are upgrading an existing installation, However, *Note
     `mysql_install_db': mysql-install-db. does not overwrite any
     existing privilege tables, so it should be safe to run in any
     circumstances.

     To initialize the grant tables, use one of the following commands,
     depending on whether *Note `mysql_install_db': mysql-install-db.
     is located in the `bin' or `scripts' directory:

          shell> bin/mysql_install_db --user=mysql
          shell> scripts/mysql_install_db --user=mysql

     It might be necessary to specify other options such as `--basedir'
     or `--datadir' if *Note `mysql_install_db': mysql-install-db. does
     not use the correct locations for the installation directory or
     data directory.  For example:

          shell> bin/mysql_install_db --user=mysql \
                   --basedir=/opt/mysql/mysql \
                   --datadir=/opt/mysql/mysql/data

     The *Note `mysql_install_db': mysql-install-db. script creates the
     server's data directory. Under the data directory, it creates
     directories for the `mysql' database that holds all database
     privileges and the `test' database that you can use to test MySQL.
     The script also creates privilege table entries for `root' and
     anonymous-user accounts. The accounts have no passwords initially.
     A description of their initial privileges is given in *Note
     default-privileges::. Briefly, these privileges allow the MySQL
     `root' user to do anything, and allow anybody to create or use
     databases with a name of `test' or starting with `test_'.

     It is important to make sure that the database directories and
     files are owned by the `mysql' login account so that the server
     has read and write access to them when you run it later. To ensure
     this, the `--user' option should be used as shown if you run *Note
     `mysql_install_db': mysql-install-db. as `root'. Otherwise, you
     should execute the script while logged in as `mysql', in which
     case you can omit the `--user' option from the command.

     *Note `mysql_install_db': mysql-install-db. creates several tables
     in the `mysql' database, including `user', `db', `host',
     `tables_priv', `columns_priv', `func', and others. See *Note
     privilege-system::, for a complete listing and description of
     these tables.

     If you don't want to have the `test' database, you can remove it
     with *Note `mysqladmin -u root drop test': mysqladmin. after
     starting the server.

     If you have trouble with *Note `mysql_install_db':
     mysql-install-db.  at this point, see *Note
     mysql-install-db-problems::.

  3. Start the MySQL server:

          shell> bin/mysqld_safe --user=mysql &

     It is important that the MySQL server be run using an unprivileged
     (non-`root') login account. To ensure this, the `--user' option
     should be used as shown if you run *Note `mysqld_safe':
     mysqld-safe. as system `root'. Otherwise, you should execute the
     script while logged in to the system as `mysql', in which case you
     can omit the `--user' option from the command.

     Further instructions for running MySQL as an unprivileged user are
     given in *Note changing-mysql-user::.

     If you neglected to create the grant tables before proceeding to
     this step, the following message appears in the error log file
     when you start the server:

          mysqld: Can't find file: 'host.frm'

     If you have other problems starting the server, see *Note
     starting-server::.

  4. Use *Note `mysqladmin': mysqladmin. to verify that the server is
     running. The following commands provide simple tests to check
     whether the server is up and responding to connections:

          shell> bin/mysqladmin version
          shell> bin/mysqladmin variables

     The output from *Note `mysqladmin version': mysqladmin. varies
     slightly depending on your platform and version of MySQL, but
     should be similar to that shown here:

          shell> bin/mysqladmin version
          mysqladmin  Ver 14.12 Distrib 6.0.12, for pc-linux-gnu on i686
          ...

          Server version          6.0.12
          Protocol version        10
          Connection              Localhost via UNIX socket
          UNIX socket             /var/lib/mysql/mysql.sock
          Uptime:                 14 days 5 hours 5 min 21 sec

          Threads: 1  Questions: 366  Slow queries: 0
          Opens: 0  Flush tables: 1  Open tables: 19
          Queries per second avg: 0.000

     To see what else you can do with *Note `mysqladmin': mysqladmin,
     invoke it with the `--help' option.

  5. Verify that you can shut down the server:

          shell> bin/mysqladmin -u root shutdown

  6. Verify that you can start the server again. Do this by using *Note
     `mysqld_safe': mysqld-safe. or by invoking *Note `mysqld': mysqld.
     directly. For example:

          shell> bin/mysqld_safe --user=mysql --log &

     If *Note `mysqld_safe': mysqld-safe. fails, see *Note
     starting-server::.

  7. Run some simple tests to verify that you can retrieve information
     from the server. The output should be similar to what is shown
     here:

          shell> bin/mysqlshow
          +-----------+
          | Databases |
          +-----------+
          | mysql     |
          | test      |
          +-----------+

          shell> bin/mysqlshow mysql
          Database: mysql
          +---------------------------+
          |          Tables           |
          +---------------------------+
          | columns_priv              |
          | db                        |
          | func                      |
          | help_category             |
          | help_keyword              |
          | help_relation             |
          | help_topic                |
          | host                      |
          | proc                      |
          | procs_priv                |
          | tables_priv               |
          | time_zone                 |
          | time_zone_leap_second     |
          | time_zone_name            |
          | time_zone_transition      |
          | time_zone_transition_type |
          | user                      |
          +---------------------------+

          shell> bin/mysql -e "SELECT Host,Db,User FROM db" mysql
          +------+--------+------+
          | host | db     | user |
          +------+--------+------+
          | %    | test   |      |
          | %    | test_% |      |
          +------+--------+------+

  8. There is a benchmark suite in the `sql-bench' directory (under the
     MySQL installation directory) that you can use to compare how
     MySQL performs on different platforms. The benchmark suite is
     written in Perl. It requires the Perl DBI module that provides a
     database-independent interface to the various databases, and some
     other additional Perl modules:

          DBI
          DBD::mysql
          Data::Dumper
          Data::ShowTable

     These modules can be obtained from CPAN (`http://www.cpan.org/').
     See also *Note perl-installation::.

     The `sql-bench/Results' directory contains the results from many
     runs against different databases and platforms. To run all tests,
     execute these commands:

          shell> cd sql-bench
          shell> perl run-all-tests

     If you don't have the `sql-bench' directory, you probably
     installed MySQL using RPM files other than the source RPM. (The
     source RPM includes the `sql-bench' benchmark directory.) In this
     case, you must first install the benchmark suite before you can
     use it. There are separate benchmark RPM files named
     `mysql-bench-VERSION.i386.rpm' that contain benchmark code and
     data.

     If you have a source distribution, there are also tests in its
     `tests' subdirectory that you can run. For example, to run
     `auto_increment.tst', execute this command from the top-level
     directory of your source distribution:

          shell> mysql -vvf test < ./tests/auto_increment.tst

     The expected result of the test can be found in the
     `./tests/auto_increment.res' file.

  9. At this point, you should have the server running. However, none
     of the initial MySQL accounts have a password, so you should
     assign passwords using the instructions found in *Note
     default-privileges::.

The MySQL 6.0 installation procedure creates time zone tables in the
`mysql' database. However, you must populate the tables manually using
the instructions in *Note time-zone-support::.


File: manual.info,  Node: mysql-install-db-problems,  Next: automatic-start,  Prev: unix-post-installation,  Up: unix-post-installation

2.10.2.1 Problems Running `mysql_install_db'
............................................

The purpose of the *Note `mysql_install_db': mysql-install-db. script
is to generate new MySQL privilege tables. It does not overwrite
existing MySQL privilege tables, and it does not affect any other data.

If you want to re-create your privilege tables, first stop the *Note
`mysqld': mysqld. server if it is running. Then rename the `mysql'
directory under the data directory to save it, and then run *Note
`mysql_install_db': mysql-install-db. Suppose that your current
directory is the MySQL installation directory and that *Note
`mysql_install_db': mysql-install-db. is located in the `bin' directory
and the data directory is named `data'. To rename the `mysql' database
and re-run *Note `mysql_install_db': mysql-install-db, use these
commands.

     shell> mv data/mysql data/mysql.old
     shell> bin/mysql_install_db --user=mysql

When you run *Note `mysql_install_db': mysql-install-db, you might
encounter the following problems:

   * **Note `mysql_install_db': mysql-install-db.  fails to install the
     grant tables*

     You may find that *Note `mysql_install_db': mysql-install-db.
     fails to install the grant tables and terminates after displaying
     the following messages:

          Starting mysqld daemon with databases from XXXXXX
          mysqld ended

     In this case, you should examine the error log file very
     carefully. The log should be located in the directory `XXXXXX'
     named by the error message and should indicate why *Note `mysqld':
     mysqld. didn't start. If you do not understand what happened,
     include the log when you post a bug report. See *Note
     bug-reports::.

   * *There is a *Note `mysqld': mysqld.  process running*

     This indicates that the server is running, in which case the grant
     tables have probably been created already. If so, there is no need
     to run *Note `mysql_install_db': mysql-install-db. at all because
     it needs to be run only once (when you install MySQL the first
     time).

   * *Installing a second *Note `mysqld': mysqld. server does not work
     when one server is running*

     This can happen when you have an existing MySQL installation, but
     want to put a new installation in a different location. For
     example, you might have a production installation, but you want to
     create a second installation for testing purposes. Generally the
     problem that occurs when you try to run a second server is that it
     tries to use a network interface that is in use by the first
     server. In this case, you should see one of the following error
     messages:

          Can't start server: Bind on TCP/IP port:
          Address already in use
          Can't start server: Bind on unix socket...

     For instructions on setting up multiple servers, see *Note
     multiple-servers::.

   * *You do not have write access to the `/tmp' directory*

     If you do not have write access to create temporary files or a
     Unix socket file in the default location (the `/tmp' directory),
     an error occurs when you run *Note `mysql_install_db':
     mysql-install-db. or the *Note `mysqld': mysqld. server.

     You can specify different locations for the temporary directory
     and Unix socket file by executing these commands prior to starting
     *Note `mysql_install_db': mysql-install-db. or *Note `mysqld':
     mysqld, where SOME_TMP_DIR is the full path name to some directory
     for which you have write permission:

          shell> TMPDIR=/SOME_TMP_DIR/
          shell> MYSQL_UNIX_PORT=/SOME_TMP_DIR/mysql.sock
          shell> export TMPDIR MYSQL_UNIX_PORT

     Then you should be able to run *Note `mysql_install_db':
     mysql-install-db. and start the server with these commands:

          shell> bin/mysql_install_db --user=mysql
          shell> bin/mysqld_safe --user=mysql &

     If *Note `mysql_install_db': mysql-install-db. is located in the
     `scripts' directory, modify the first command to
     `scripts/mysql_install_db'.

     See *Note problems-with-mysql-sock::, and *Note
     environment-variables::.

There are some alternatives to running the *Note `mysql_install_db':
mysql-install-db. script provided in the MySQL distribution:

   * If you want the initial privileges to be different from the
     standard defaults, you can modify *Note `mysql_install_db':
     mysql-install-db. before you run it.  However, it is preferable to
     use *Note `GRANT': grant. and *Note `REVOKE': revoke. to change the
     privileges _after_ the grant tables have been set up. In other
     words, you can run *Note `mysql_install_db': mysql-install-db, and
     then use `mysql -u root mysql' to connect to the server as the
     MySQL `root' user so that you can issue the necessary *Note
     `GRANT': grant. and *Note `REVOKE': revoke. statements.

     If you want to install MySQL on several machines with the same
     privileges, you can put the *Note `GRANT': grant. and *Note
     `REVOKE': revoke. statements in a file and execute the file as a
     script using `mysql' after running *Note `mysql_install_db':
     mysql-install-db. For example:

          shell> bin/mysql_install_db --user=mysql
          shell> bin/mysql -u root < your_script_file

     By doing this, you can avoid having to issue the statements
     manually on each machine.

   * It is possible to re-create the grant tables completely after they
     have previously been created. You might want to do this if you're
     just learning how to use *Note `GRANT': grant. and *Note `REVOKE':
     revoke. and have made so many modifications after running *Note
     `mysql_install_db': mysql-install-db. that you want to wipe out
     the tables and start over.

     To re-create the grant tables, remove all the `.frm', `.MYI', and
     `.MYD' files in the `mysql' database directory. Then run the *Note
     `mysql_install_db': mysql-install-db. script again.

   * You can start *Note `mysqld': mysqld. manually using the
     `--skip-grant-tables' option and add the privilege information
     yourself using *Note `mysql': mysql.:

          shell> bin/mysqld_safe --user=mysql --skip-grant-tables &
          shell> bin/mysql mysql

     From *Note `mysql': mysql, manually execute the SQL commands
     contained in *Note `mysql_install_db': mysql-install-db.  Make
     sure that you run *Note `mysqladmin flush-privileges': mysqladmin.
     or *Note `mysqladmin reload': mysqladmin. afterward to tell the
     server to reload the grant tables.

     Note that by not using *Note `mysql_install_db': mysql-install-db,
     you not only have to populate the grant tables manually, you also
     have to create them first.


File: manual.info,  Node: automatic-start,  Next: starting-server,  Prev: mysql-install-db-problems,  Up: unix-post-installation

2.10.2.2 Starting and Stopping MySQL Automatically
..................................................

Generally, you start the *Note `mysqld': mysqld. server in one of these
ways:

   * By invoking *Note `mysqld': mysqld. directly. This works on any
     platform.

   * By running the MySQL server as a Windows service. The service can
     be set to start the server automatically when Windows starts, or
     as a manual service that you start on request. For instructions,
     see *Note windows-start-service::.

   * By invoking *Note `mysqld_safe': mysqld-safe, which tries to
     determine the proper options for *Note `mysqld': mysqld.  and then
     runs it with those options. This script is used on Unix and
     Unix-like systems. See *Note mysqld-safe::.

   * By invoking *Note `mysql.server': mysql-server. This script is
     used primarily at system startup and shutdown on systems that use
     System V-style run directories, where it usually is installed
     under the name `mysql'. The *Note `mysql.server': mysql-server.
     script starts the server by invoking *Note `mysqld_safe':
     mysqld-safe. See *Note mysql-server::.

   * On Mac OS X, you can install a separate MySQL Startup Item package
     to enable the automatic startup of MySQL on system startup. The
     Startup Item starts the server by invoking *Note `mysql.server':
     mysql-server. See *Note mac-os-x-installation::, for details.

The *Note `mysqld_safe': mysqld-safe. and *Note `mysql.server':
mysql-server. scripts and the Mac OS X Startup Item can be used to
start the server manually, or automatically at system startup time.
*Note `mysql.server': mysql-server. and the Startup Item also can be
used to stop the server.

To start or stop the server manually using the *Note `mysql.server':
mysql-server. script, invoke it with `start' or `stop' arguments:

     shell> mysql.server start
     shell> mysql.server stop

Before *Note `mysql.server': mysql-server. starts the server, it
changes location to the MySQL installation directory, and then invokes
*Note `mysqld_safe': mysqld-safe. If you want the server to run as some
specific user, add an appropriate `user' option to the `[mysqld]' group
of the `/etc/my.cnf' option file, as shown later in this section. (It
is possible that you will need to edit *Note `mysql.server':
mysql-server. if you've installed a binary distribution of MySQL in a
non-standard location. Modify it to `cd' into the proper directory
before it runs *Note `mysqld_safe': mysqld-safe. If you do this, your
modified version of *Note `mysql.server': mysql-server. may be
overwritten if you upgrade MySQL in the future, so you should make a
copy of your edited version that you can reinstall.)

*Note `mysql.server stop': mysql-server. stops the server by sending a
signal to it. You can also stop the server manually by executing *Note
`mysqladmin shutdown': mysqladmin.

To start and stop MySQL automatically on your server, you need to add
start and stop commands to the appropriate places in your `/etc/rc*'
files.

If you use the Linux server RPM package (`MySQL-server-VERSION.rpm'),
the *Note `mysql.server': mysql-server. script is installed in the
`/etc/init.d' directory with the name `mysql'. You need not install it
manually.  See *Note linux-rpm::, for more information on the Linux RPM
packages.

Some vendors provide RPM packages that install a startup script under a
different name such as *Note `mysqld': mysqld.

If you install MySQL from a source distribution or using a binary
distribution format that does not install *Note `mysql.server':
mysql-server. automatically, you can install it manually. The script
can be found in the `support-files' directory under the MySQL
installation directory or in a MySQL source tree.

To install *Note `mysql.server': mysql-server. manually, copy it to the
`/etc/init.d' directory with the name *Note `mysql': mysql, and then
make it executable. Do this by changing location into the appropriate
directory where *Note `mysql.server': mysql-server. is located and
executing these commands:

     shell> cp mysql.server /etc/init.d/mysql
     shell> chmod +x /etc/init.d/mysql

Older Red Hat systems use the `/etc/rc.d/init.d' directory rather than
`/etc/init.d'. Adjust the preceding commands accordingly.
Alternatively, first create `/etc/init.d' as a symbolic link that
points to `/etc/rc.d/init.d':

     shell> cd /etc
     shell> ln -s rc.d/init.d .

After installing the script, the commands needed to activate it to run
at system startup depend on your operating system.  On Linux, you can
use `chkconfig':

     shell> chkconfig --add mysql

On some Linux systems, the following command also seems to be necessary
to fully enable the *Note `mysql': mysql. script:

     shell> chkconfig --level 345 mysql on

On FreeBSD, startup scripts generally should go in
`/usr/local/etc/rc.d/'. The `rc(8)' manual page states that scripts in
this directory are executed only if their basename matches the `*.sh'
shell file name pattern. Any other files or directories present within
the directory are silently ignored. In other words, on FreeBSD, you
should install the `mysql.server' script as
`/usr/local/etc/rc.d/mysql.server.sh' to enable automatic startup.

As an alternative to the preceding setup, some operating systems also
use `/etc/rc.local' or `/etc/init.d/boot.local' to start additional
services on startup. To start up MySQL using this method, you could
append a command like the one following to the appropriate startup file:

     /bin/sh -c 'cd /usr/local/mysql; ./bin/mysqld_safe --user=mysql &'

For other systems, consult your operating system documentation to see
how to install startup scripts.

You can add options for *Note `mysql.server': mysql-server. in a global
`/etc/my.cnf' file. A typical `/etc/my.cnf' file might look like this:

     [mysqld]
     datadir=/usr/local/mysql/var
     socket=/var/tmp/mysql.sock
     port=3306
     user=mysql

     [mysql.server]
     basedir=/usr/local/mysql

The *Note `mysql.server': mysql-server. script supports the following
options: `basedir', `datadir', and `pid-file'. If specified, they
_must_ be placed in an option file, not on the command line.  *Note
`mysql.server': mysql-server. supports only `start' and `stop' as
command-line arguments.

The following table shows which option groups the server and each
startup script read from option files.

*Script*       *Option Groups*
*Note          `[mysqld]', `[server]', `[mysqld-MAJOR_VERSION]'
`mysqld':      
mysqld.        
*Note          `[mysqld]', `[server]', `[mysqld_safe]'
`mysqld_safe': 
mysqld-safe.   
*Note          `[mysqld]', `[mysql.server]', `[server]'
`mysql.server':
mysql-server.  

`[mysqld-MAJOR_VERSION]' means that groups with names like
`[mysqld-5.1]' and `[mysqld-6.0]' are read by servers having versions
5.1.x, 6.0.x, and so forth. This feature can be used to specify options
that can be read only by servers within a given release series.

For backward compatibility, *Note `mysql.server': mysql-server.  also
reads the `[mysql_server]' group and *Note `mysqld_safe': mysqld-safe.
also reads the `[safe_mysqld]' group. However, you should update your
option files to use the `[mysql.server]' and `[mysqld_safe]' groups
instead when using MySQL 6.0.

See *Note option-files::.


File: manual.info,  Node: starting-server,  Prev: automatic-start,  Up: unix-post-installation

2.10.2.3 Starting and Troubleshooting the MySQL Server
......................................................

This section provides troubleshooting suggestions for problems starting
the server on Unix. If you are using Windows, see *Note
windows-troubleshooting::.

If you have problems starting the server, here are some things to try:

   * Check the error log to see why the server does not start.

   * Specify any special options needed by the storage engines you are
     using.

   * Make sure that the server knows where to find the data directory.

   * Make sure that the server can access the data directory.  The
     ownership and permissions of the data directory and its contents
     must be set such that the server can read and modify them.

   * Verify that the network interfaces the server wants to use are
     available.

Some storage engines have options that control their behavior.  You can
create a `my.cnf' file and specify startup options for the engines that
you plan to use. If you are going to use storage engines that support
transactional tables (`InnoDB', `NDB'), be sure that you have them
configured the way you want before starting the server:

MySQL Enterprise

For expert advice on start-up options appropriate to your
circumstances, subscribe to The MySQL Enterprise Monitor.  For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

   * If you are using `InnoDB' tables, see *Note innodb-configuration::.

Storage engines will use default option values if you specify none, but
it is recommended that you review the available options and specify
explicit values for those for which the defaults are not appropriate
for your installation.

When the *Note `mysqld': mysqld. server starts, it changes location to
the data directory. This is where it expects to find databases and
where it expects to write log files. The server also writes the pid
(process ID) file in the data directory.

The data directory location is hardwired in when the server is
compiled. This is where the server looks for the data directory by
default. If the data directory is located somewhere else on your
system, the server will not work properly. You can determine what the
default path settings are by invoking *Note `mysqld': mysqld. with the
`--verbose' and `--help' options.

If the default locations don't match the MySQL installation layout on
your system, you can override them by specifying options to *Note
`mysqld': mysqld. or *Note `mysqld_safe': mysqld-safe. on the command
line or in an option file.

To specify the location of the data directory explicitly, use the
`--datadir' option. However, normally you can tell *Note `mysqld':
mysqld. the location of the base directory under which MySQL is
installed and it looks for the data directory there. You can do this
with the `--basedir' option.

To check the effect of specifying path options, invoke *Note `mysqld':
mysqld. with those options followed by the `--verbose' and `--help'
options. For example, if you change location into the directory where
*Note `mysqld': mysqld. is installed and then run the following
command, it shows the effect of starting the server with a base
directory of `/usr/local':

     shell> ./mysqld --basedir=/usr/local --verbose --help

You can specify other options such as `--datadir' as well, but
`--verbose' and `--help' must be the last options.

Once you determine the path settings you want, start the server without
`--verbose' and `--help'.

If *Note `mysqld': mysqld. is currently running, you can find out what
path settings it is using by executing this command:

     shell> mysqladmin variables

Or:

     shell> mysqladmin -h HOST_NAME variables

HOST_NAME is the name of the MySQL server host.

If you get `Errcode 13' (which means `Permission denied') when starting
*Note `mysqld': mysqld, this means that the privileges of the data
directory or its contents do not allow the server access. In this case,
you change the permissions for the involved files and directories so
that the server has the right to use them. You can also start the
server as `root', but this raises security issues and should be avoided.

On Unix, change location into the data directory and check the
ownership of the data directory and its contents to make sure the
server has access. For example, if the data directory is
`/usr/local/mysql/var', use this command:

     shell> ls -la /usr/local/mysql/var

If the data directory or its files or subdirectories are not owned by
the login account that you use for running the server, change their
ownership to that account. If the account is named `mysql', use these
commands:

     shell> chown -R mysql /usr/local/mysql/var
     shell> chgrp -R mysql /usr/local/mysql/var

If the server fails to start up correctly, check the error log. Log
files are located in the data directory (typically `C:\Program
Files\MySQL\MySQL Server 6.0\data' on Windows, `/usr/local/mysql/data'
for a Unix binary distribution, and `/usr/local/var' for a Unix source
distribution). Look in the data directory for files with names of the
form `HOST_NAME.err' and `HOST_NAME.log', where HOST_NAME is the name
of your server host. Then examine the last few lines of these files.
On Unix, you can use `tail' to display them:

     shell> tail HOST_NAME.err
     shell> tail HOST_NAME.log

The error log should contain information that indicates why the server
couldn't start.

If either of the following errors occur, it means that some other
program (perhaps another *Note `mysqld': mysqld.  server) is using the
TCP/IP port or Unix socket file that *Note `mysqld': mysqld. is trying
to use:

     Can't start server: Bind on TCP/IP port: Address already in use
     Can't start server: Bind on unix socket...

Use `ps' to determine whether you have another *Note `mysqld': mysqld.
server running. If so, shut down the server before starting *Note
`mysqld': mysqld.  again. (If another server is running, and you really
want to run multiple servers, you can find information about how to do
so in *Note multiple-servers::.)

If no other server is running, try to execute the command `telnet
YOUR_HOST_NAME TCP_IP_PORT_NUMBER'. (The default MySQL port number is
3306.) Then press Enter a couple of times. If you don't get an error
message like `telnet: Unable to connect to remote host: Connection
refused', some other program is using the TCP/IP port that *Note
`mysqld': mysqld. is trying to use. You'll need to track down what
program this is and disable it, or else tell *Note `mysqld': mysqld. to
listen to a different port with the `--port' option. In this case,
you'll also need to specify the port number for client programs when
connecting to the server via TCP/IP.

Another reason the port might be inaccessible is that you have a
firewall running that blocks connections to it. If so, modify the
firewall settings to allow access to the port.

If the server starts but you can't connect to it, you should make sure
that you have an entry in `/etc/hosts' that looks like this:

     127.0.0.1       localhost

This problem occurs only on systems that do not have a working thread
library and for which MySQL must be configured to use MIT-pthreads.

If you cannot get *Note `mysqld': mysqld. to start, you can try to make
a trace file to find the problem by using the `--debug' option. See
MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).


File: manual.info,  Node: default-privileges,  Prev: unix-post-installation,  Up: post-installation

2.10.3 Securing the Initial MySQL Accounts
------------------------------------------

Part of the MySQL installation process is to set up the `mysql'
database that contains the grant tables:

   * Windows distributions contain preinitialized grant tables that are
     installed automatically.

   * On Unix, the grant tables are populated by the *Note
     `mysql_install_db': mysql-install-db. program. Some installation
     methods run this program for you. Others require that you execute
     it manually. For details, see *Note unix-post-installation::.

The grant tables define the initial MySQL user accounts and their
access privileges. These accounts are set up as follows:

   * Accounts with the user name `root' are created. These are
     superuser accounts that can do anything.  The initial `root'
     account passwords are empty, so anyone can connect to the MySQL
     server as `root' -- _without a password_ -- and be granted all
     privileges.

        * On Windows, one `root' account is created; this account
          allows connecting from the local host only. The Windows
          installer will optionally create an account allowing for
          connections from any host only if the user selects the
          `Enable root access from remote machines' option during
          installation.

        * On Unix, both `root' accounts are for connections from the
          local host. Connections must be made from the local host by
          specifying a host name of `localhost' for one of the
          accounts, or the actual host name or IP number for the other.

   * Two anonymous-user accounts are created, each with an empty user
     name. The anonymous accounts have no password, so anyone can use
     them to connect to the MySQL server.

        * On Windows, one anonymous account is for connections from the
          local host. It has no global privileges. The other is for
          connections from any host and has all privileges for the
          `test' database and for other databases with names that start
          with `test'.

        * On Unix, both anonymous accounts are for connections from the
          local host. Connections must be made from the local host by
          specifying a host name of `localhost' for one of the
          accounts, or the actual host name or IP number for the other.
          These accounts have all privileges for the `test' database
          and for other databases with names that start with `test_'.

As noted, none of the initial accounts have passwords. This means that
your MySQL installation is unprotected until you do something about it:

   * If you want to prevent clients from connecting as anonymous users
     without a password, you should either assign a password to each
     anonymous account or else remove the accounts.

   * You should assign a password to each MySQL `root' account.

The following instructions describe how to set up passwords for the
initial MySQL accounts, first for the anonymous accounts and then for
the `root' accounts. Replace `NEWPWD' in the examples with the actual
password that you want to use. The instructions also cover how to
remove the anonymous accounts, should you prefer not to allow anonymous
access at all.

You might want to defer setting the passwords until later, so that you
don't need to specify them while you perform additional setup or
testing. However, be sure to set them before using your installation
for production purposes.

*Anonymous Account Password Assignment*

To assign passwords to the anonymous accounts, connect to the server as
`root' and then use either *Note `SET PASSWORD': set-password. or *Note
`UPDATE': update. In either case, be sure to encrypt the password using
the `PASSWORD()' function.

To use *Note `SET PASSWORD': set-password. on Windows, do this:

     shell> mysql -u root
     mysql> SET PASSWORD FOR ''@'localhost' = PASSWORD('NEWPWD');
     mysql> SET PASSWORD FOR ''@'%' = PASSWORD('NEWPWD');

To use *Note `SET PASSWORD': set-password. on Unix, do this:

     shell> mysql -u root
     mysql> SET PASSWORD FOR ''@'localhost' = PASSWORD('NEWPWD');
     mysql> SET PASSWORD FOR ''@'HOST_NAME' = PASSWORD('NEWPWD');

In the second *Note `SET PASSWORD': set-password.  statement, replace
HOST_NAME with the name of the server host. This is the name that is
specified in the `Host' column of the non-`localhost' record for `root'
in the `user' table. If you don't know what host name this is, issue
the following statement before using *Note `SET PASSWORD':
set-password.:

     mysql> SELECT Host, User FROM mysql.user;

Look for the record that has `root' in the `User' column and something
other than `localhost' in the `Host' column. Then use that `Host' value
in the second *Note `SET PASSWORD': set-password. statement.

*Anonymous Account Removal*

If you prefer to remove the anonymous accounts instead, do so as
follows:

     shell> mysql -u root
     mysql> DROP USER '';

The `DROP' statement applies both to Windows and to Unix. On Windows,
if you want to remove only the anonymous account that has the same
privileges as `root', do this instead:

     shell> mysql -u root
     mysql> DROP USER ''@'localhost';

That account allows anonymous access but has full privileges, so
removing it improves security.

*`root' Account Password Assignment*

You can assign passwords to the `root' accounts in several ways. The
following discussion demonstrates three methods:

   * Use the *Note `SET PASSWORD': set-password.  statement

   * Use the *Note `mysqladmin': mysqladmin. command-line client program

   * Use the *Note `UPDATE': update. statement

To assign passwords using *Note `SET PASSWORD': set-password, connect
to the server as `root' and issue *Note `SET PASSWORD': set-password.
statements. Be sure to encrypt the password using the `PASSWORD()'
function.

For Windows, do this:

     shell> mysql -u root
     mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD('NEWPWD');
     mysql> SET PASSWORD FOR 'root'@'%' = PASSWORD('NEWPWD');

For Unix, do this:

     shell> mysql -u root
     mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD('NEWPWD');
     mysql> SET PASSWORD FOR 'root'@'HOST_NAME' = PASSWORD('NEWPWD');

In the second *Note `SET PASSWORD': set-password.  statement, replace
HOST_NAME with the name of the server host. This is the same host name
that you used when you assigned the anonymous account passwords.

If the `user' table contains an account with `User' and `Host' values of
`'root'' and `'127.0.0.1'', use an additional *Note `SET PASSWORD':
set-password.  statement to set that account's password:

     mysql> SET PASSWORD FOR 'root'@'127.0.0.1' = PASSWORD('NEWPWD');

To assign passwords to the `root' accounts using *Note `mysqladmin':
mysqladmin, execute the following commands:

     shell> mysqladmin -u root password "NEWPWD"
     shell> mysqladmin -u root -h HOST_NAME password "NEWPWD"

These commands apply both to Windows and to Unix. In the second
command, replace HOST_NAME with the name of the server host. The double
quotes around the password are not always necessary, but you should use
them if the password contains spaces or other characters that are
special to your command interpreter.

The *Note `mysqladmin': mysqladmin. method of setting the `root'
account passwords does not set the password for the
`'root'@'127.0.0.1'' account.  To do so, use *Note `SET PASSWORD':
set-password. as shown earlier.

You can also use *Note `UPDATE': update. to modify the `user' table
directly. The following *Note `UPDATE': update. statement assigns a
password to all `root' accounts:

     shell> mysql -u root
     mysql> UPDATE mysql.user SET Password = PASSWORD('NEWPWD')
         ->     WHERE User = 'root';
     mysql> FLUSH PRIVILEGES;

The *Note `UPDATE': update. statement applies both to Windows and to
Unix.

After the passwords have been set, you must supply the appropriate
password whenever you connect to the server. For example, if you want
to use *Note `mysqladmin': mysqladmin. to shut down the server, you can
do so using this command:

     shell> mysqladmin -u root -p shutdown
     Enter password: (ENTER ROOT PASSWORD HERE)

*Note*:

If you forget your `root' password after setting it up, *Note
resetting-permissions::, covers the procedure for resetting it.

To set up additional accounts, you can use the *Note `GRANT': grant.
statement. For instructions, see *Note adding-users::.


File: manual.info,  Node: upgrade-downgrade,  Next: operating-system-specific-notes,  Prev: post-installation,  Up: installing

2.11 Upgrading or Downgrading MySQL
===================================

* Menu:

* upgrade::                      Upgrading MySQL
* downgrading::                  Downgrading MySQL
* checking-index-changes::       Checking Whether Table Indexes Must Be Rebuilt
* rebuilding-tables::            Rebuilding Tables or Table Indexes
* copying-databases::            Copying MySQL Databases to Another Machine


File: manual.info,  Node: upgrade,  Next: downgrading,  Prev: upgrade-downgrade,  Up: upgrade-downgrade

2.11.1 Upgrading MySQL
----------------------

* Menu:

* upgrading-from-5-1::           Upgrading from MySQL 5.1 to 6.0

As a general rule, we recommend that when you upgrade from one release
series to another, you should go to the next series rather than
skipping a series. If you wish to upgrade from a release series
previous to MySQL 5.1, you should upgrade to each successive release
series in turn until you have reached MySQL 5.1, and then proceed with
the upgrade to MySQL 6.0. For example, if you currently are running
MySQL 4.1 and wish to upgrade to a newer series, upgrade to MySQL 5.0
first before upgrading to 5.1, and so forth. For information on
upgrading to MySQL 5.1, see the `MySQL 5.1 Reference Manual'.

The following items form a checklist of things that you should do
whenever you perform an upgrade from MySQL 5.1 to 6.0:

   * Before any upgrade, back up your databases, including the `mysql'
     database that contains the grant tables.

   * Read _all_ the notes in *Note upgrading-from-5-1::. These notes
     will enable you to identify upgrade issues that apply to your
     current MySQL installation. Read *Note news:: as well, which
     provides information about features that are new in MySQL 6.0 or
     differ from those found in MySQL 5.1.

   * For any incompatibilities that require your attention _before_
     upgrading, deal with them as described in *Note
     upgrading-from-5-1::.

   * After you upgrade to a new version of MySQL, you should run *Note
     `mysql_upgrade': mysql-upgrade. (see *Note mysql-upgrade::). This
     program will check your tables, and repair them if necessary. It
     will also update your grant tables to make sure that they have the
     current structure so that you can take advantage of any new
     capabilities. (Some releases of MySQL introduce changes to the
     structure of the grant tables to add new privileges or features.)

   * If you are running MySQL Server on Windows, see *Note
     windows-upgrading::.

   * If you are using replication, see *Note replication-upgrade::, for
     information on upgrading your replication setup.

   * If you are upgrading an installation originally produced by
     installing multiple RPM packages, it is best to upgrade all the
     packages, not just some. For example, if you previously installed
     the server and client RPMs, do not upgrade just the server RPM.

   * If you have created a user-defined function (UDF) with a given
     name and upgrade MySQL to a version that implements a new built-in
     function with the same name, the UDF becomes inaccessible. To
     correct this, use *Note `DROP FUNCTION': drop-function. to drop
     the UDF, and then use *Note `CREATE FUNCTION': create-function. to
     re-create the UDF with a different non-conflicting name. The same
     is true if the new version of MySQL implements a built-in function
     with the same name as an existing stored function.  See *Note
     function-resolution::, for the rules describing how the server
     interprets references to different kinds of functions.

You can always move the MySQL format files and data files between
different versions on the same architecture as long as you stay within
versions for the same release series of MySQL.

If you are cautious about using new versions, you can always rename
your old *Note `mysqld': mysqld. before installing a newer one. For
example, if you are using MySQL 5.1.13 and want to upgrade to 6.0.10,
rename your current server from *Note `mysqld': mysqld. to
`mysqld-5.1.13'. If your new *Note `mysqld': mysqld. then does
something unexpected, you can simply shut it down and restart with your
old *Note `mysqld': mysqld.

If, after an upgrade, you experience problems with recompiled client
programs, such as `Commands out of sync' or unexpected core dumps, you
probably have used old header or library files when compiling your
programs. In this case, you should check the date for your `mysql.h'
file and `libmysqlclient.a' library to verify that they are from the
new MySQL distribution. If not, recompile your programs with the new
headers and libraries.

If problems occur, such as that the new *Note `mysqld': mysqld. server
does not start or that you cannot connect without a password, verify
that you do not have an old `my.cnf' file from your previous
installation. You can check this with the `--print-defaults' option (for
example, *Note `mysqld --print-defaults': mysqld.). If this command
displays anything other than the program name, you have an active
`my.cnf' file that affects server or client operation.

It is a good idea to rebuild and reinstall the Perl `DBD::mysql' module
whenever you install a new release of MySQL. The same applies to other
MySQL interfaces as well, such as the PHP `mysql' extension and the
Python `MySQLdb' module.


File: manual.info,  Node: upgrading-from-5-1,  Prev: upgrade,  Up: upgrade

2.11.1.1 Upgrading from MySQL 5.1 to 6.0
........................................

*Note*:

It is good practice to back up your data before installing any new
version of software. Although MySQL works very hard to ensure a high
level of quality, you should protect your data by making a backup.
MySQL recommends that you dump and reload your tables from any previous
version to upgrade to 6.0.

In general, you should do the following when upgrading from MySQL 5.1
to 6.0:

   * Read _all_ the items in the following sections to see whether any
     of them might affect your applications:

        * *Note upgrade::, has general update information.

        * The items in the change lists found later in this section
          enable you to identify upgrade issues that apply to your
          current MySQL installation.

        * The MySQL 6.0 change history describes significant new
          features you can use in 6.0 or that differ from those found in
          MySQL 5.1. Some of these changes may result in
          incompatibilities. See *Note news-6-0-x::.

   * Note particularly any changes that are marked *Known issue* or
     *Incompatible change*.  These incompatibilities with earlier
     versions of MySQL may require your attention _before you upgrade_.

     Our aim is to avoid these changes, but occasionally they are
     necessary to correct problems that would be worse than an
     incompatibility between releases. If any upgrade issue applicable
     to your installation involves an incompatibility that requires
     special handling, follow the instructions given in the
     incompatibility description.  Often this will involve a dump and
     reload, or use of a statement such as *Note `CHECK TABLE':
     check-table. or *Note `REPAIR TABLE': repair-table.

     For dump and reload instructions, see *Note rebuilding-tables::.
     Any procedure that involves *Note `REPAIR TABLE': repair-table.
     with the `USE_FRM' option _must_ be done before upgrading. Use of
     this statement with a version of MySQL different from the one used
     to create the table (that is, using it after upgrading) may damage
     the table. See *Note repair-table::.

   * After you upgrade to a new version of MySQL, run *Note
     `mysql_upgrade': mysql-upgrade. (see *Note mysql-upgrade::). This
     program will check your tables, and repair them if necessary. It
     will also update your grant tables to make sure that they have the
     current structure so that you can take advantage of any new
     capabilities. (Some releases of MySQL introduce changes to the
     structure of the grant tables to add new privileges or features.)

   * Check *Note checking-index-changes::, to see whether changes to
     character sets or collations were made that affect your table
     indexes. If so, you will need to rebuild the affected indexes
     using the instructions in *Note rebuilding-tables::.

   * If you are running MySQL Server on Windows, see *Note
     windows-upgrading::.

   * If you are using replication, see *Note replication-upgrade::, for
     information on upgrading your replication setup.

The following lists describe changes that may affect applications and
that you should watch out for when upgrading to MySQL 6.0.

*Server Changes:*

   * *Known issue*: MySQL introduces encoding for table names that have
     non-ASCII characters (see *Note identifier-mapping::).  After a
     live upgrade from MySQL 5.0 to 5.1 or higher, the server
     recognizes names that have non-ASCII characters and adds a
     `#mysql50#' prefix to them.  Running *Note `mysqlcheck
     --all-databases --check-upgrade --fix-db-names --fix-table-names':
     mysqlcheck.  later upgrades these names by encoding them with the
     new format and removes the `#mysql50#' prefix.

     *Note `mysql_upgrade': mysql-upgrade. executes the following
     commands to check and repair tables and to upgrade the system
     tables. FIX_PRIV_TABLES represents a script generated interally by
     *Note `mysql_upgrade': mysql-upgrade. that contains SQL statements
     to upgrade the tables in the `mysql' database:

          mysqlcheck --check-upgrade --all-databases --auto-repair
          mysql < FIX_PRIV_TABLES
          mysqlcheck --all-databases --check-upgrade --fix-db-names --fix-table-names

     However, prior to MySQL 6.0.10, *Note `mysql_upgrade':
     mysql-upgrade. does not run the third command, which is necessary
     to re-encode database or table names that contain non-alphanumeric
     characters. (They still appear after the upgrade with the
     `#mysql50#' prefix.) If you have such database or table names,
     execute the third command manually after executing *Note
     `mysql_upgrade': mysql-upgrade.  This problem is fixed as of MySQL
     6.0.10.

   * *Known issue*: Before MySQL 6.0.8, the *Note `CHECK TABLE ... FOR
     UPGRADE': check-table. statement did not check for incompatible
     collation changes made in MySQL 5.1.24. (This also affects *Note
     `mysqlcheck': mysqlcheck. and *Note `mysql_upgrade':
     mysql-upgrade, which cause that statement to be executed.)

     Prior to the fix made in 6.0.8, a binary upgrade (performed
     without dumping tables with *Note `mysqldump': mysqldump. before
     the upgrade and reloading the dump file after the upgrade) would
     corrupt tables. After the fix, *Note `CHECK TABLE ... FOR
     UPGRADE': check-table. properly detects the problem and warns
     about tables that need repair.

     However, the fix is not backward compatible and can result in a
     downgrading problem under these circumstances:

       1. Perform a binary upgrade to a version of MySQL that includes
          the fix.

       2. Run *Note `CHECK TABLE ... FOR UPGRADE': check-table. (or
          *Note `mysqlcheck': mysqlcheck. or *Note `mysql_upgrade':
          mysql-upgrade.) to upgrade tables.

       3. Perform a binary downgrade to a version of MySQL that does
          not include the fix.

     The solution is to dump tables with *Note `mysqldump': mysqldump.
     before the downgrade and reload the dump file after the downgrade.
     Alternatively, drop and recreate affected indexes.

   * *Incompatible change*: From MySQL 6.0.5 to 6.0.9, the *Note
     `UPDATE': update. statement was changed such that assigning `NULL'
     to a `NOT NULL' column caused an error even when strict SQL mode
     was not enabled. The original behavior before MySQL 6.0.5 was that
     such assignments caused an error only in strict SQL mode, and
     otherwise set the column to the the implicit default value for the
     column data type and generated a warning. (For information about
     implicit default values, see *Note data-type-defaults::.)

     The change caused compatibility problems for applications that
     relied on the original behavior. It also caused replication
     problems between servers that had the original behavior and those
     that did not, for applications that assigned `NULL' to `NOT NULL'
     columns in *Note `UPDATE': update. statements without strict SQL
     mode enabled. The change was reverted in MySQL 6.0.10 so that
     *Note `UPDATE': update. again had the original behavior. Problems
     can still occur if you replicate between servers that have the
     modified *Note `UPDATE': update. behavior and those that do not.

   * *Incompatible change*: Character set or collation changes were
     made in MySQL 6.0.1, 6.0.5, and 6.0.6 that may require table
     indexes to be rebuilt. For details, see *Note
     checking-index-changes::.

   * *Incompatible change*: In connection with view creation, the
     server created `arc' directories inside database directories and
     maintained useless copies of `.frm' files there. Creation and
     renaming procedures of those copies as well as creation of `arc'
     directories has been discontinued in MySQL 6.0.8.

     This change does cause a problem when downgrading to older server
     versions which manifests itself under these circumstances:

       1. Create a view `v_orig' in MySQL 6.0.8 or higher.

       2. Rename the view to `v_new' and then back to `v_orig'.

       3. Downgrade to an older 6.0.x server and run *Note
          `mysql_upgrade': mysql-upgrade.

       4. Try to rename `v_orig' to `v_new' again. This operation fails.

     As a workaround to avoid this problem, use either of these
     approaches:

        * Dump your data using *Note `mysqldump': mysqldump.  before
          downgrading and reload the dump file after downgrading.

        * Instead of renaming a view after the downgrade, drop it and
          recreate it.

   * *Incompatible change*: In MySQL 6.0.6, a change was made to the
     way that the server handles prepared statements. This affects
     prepared statements processed at the SQL level (using the *Note
     `PREPARE': prepare. statement) and those processed using the
     binary client-server protocol (using the *Note
     `mysql_stmt_prepare()': mysql-stmt-prepare. C API function).

     Previously, changes to metadata of tables or views referred to in
     a prepared statement could cause a server crash when the statement
     was next executed, or perhaps an error at execute time with a
     crash occurring later. For example, this could happen after
     dropping a table and recreating it with a different definition.

     Now metadata changes to tables or views referred to by prepared
     statements are detected and cause automatic repreparation of the
     statement when it is next executed.  Metadata changes occur for
     DDL statements such as those that create, drop, alter, rename, or
     truncate tables, or that analyze, optimize, or repair tables.
     Repreparation also occurs after referenced tables or views are
     flushed from the table definition cache, either implicitly to make
     room for new entries in the cache, or explicitly due to *Note
     `FLUSH TABLES': flush.

     Repreparation is automatic, but to the extent that it occurs,
     performance of prepared statements is diminished.

     Table content changes (for example, with *Note `INSERT': insert. or
     *Note `UPDATE': update.) do not cause repreparation, nor do *Note
     `SELECT': select. statements.

     An incompatibility with previous versions of MySQL is that a
     prepared statement may now return a different set of columns or
     different column types from one execution to the next. For
     example, if the prepared statement is `SELECT * FROM t1', altering
     `t1' to contain a different number of columns causes the next
     execution to return a number of columns different from the
     previous execution.

     Older versions of the client library cannot handle this change in
     behavior. For applications that use prepared statements with the
     new server, an upgrade to the new client library is strongly
     recommended.

     Along with this change to statement repreparation, the default
     value of the `table_definition_cache' system variable has been
     increased from 128 to 256. The purpose of this increase is to
     lessen the chance that prepared statements will need repreparation
     due to referred-to tables/views having been flushed from the cache
     to make room for new entries.

     A new status variable, `Com_stmt_reprepare', has been introduced
     to track the number of repreparations.

   * *Incompatible change*: As of MySQL 6.0.5, the server includes
     `dtoa', a library for conversion between strings and numbers by
     David M. Gay. In MySQL, this library provides the basis for
     improved conversion between string or *Note `DECIMAL':
     numeric-types. values and approximate-value (FLOAT/DOUBLE) numbers:

        * Consistent conversion results across platforms, which
          eliminates, for example, Unix versus Windows conversion
          differences.

        * Accurate representation of values in cases where results
          previously did not provide sufficient precision, such as for
          values close to IEEE limits.

        * Conversion of numbers to string format with the best possible
          precision. The precision of `dtoa' is always the same or
          bettter than that of the standard C library functions.

     Because the conversions produced by this library differ in some
     cases from previous results, the potential exists for
     incompatibilities in applications that rely on previous results.
     For example, applications that depend on a specific exact result
     from previous conversions might need adjustment to accommodate
     additional precision.

     For additional information about the properties of `dtoa'
     conversions, see *Note type-conversion::.

   * *Incompatible change:* *Note `SHOW CREATE VIEW': show-create-view.
     displays view definitions using an `AS ALIAS_NAME' clause for each
     column. If a column is created from an expression, the default
     alias is the expression text, which can be quite long. As of MySQL
     6.0.4, aliases for column names in *Note `CREATE VIEW':
     create-view. statements are checked against the maximum column
     length of 64 characters (not the maximum alias length of 256
     characters). As a result, views created from the output of *Note
     `SHOW CREATE VIEW': show-create-view. fail if any column alias
     exceeds 64 characters. This can cause problems for replication or
     loading dump files. For additional information and workarounds, see
     *Note view-restrictions::.

   * *Incompatible change:* As of MySQL 6.0.4, the Unicode
     implementation has been extended to provide support for
     supplementary characters that lie outside the Basic Multilingual
     Plane (BMP).  Noteworthy features:

        * `utf16' and `utf32' character sets have been added. These
          correspond to the UTF-16 and UTF-32 encodings of the Unicode
          character set, and they both support supplementary characters.

        * The `utf8' character set from previous versions of MySQL has
          been renamed to `utf8mb3', to reflect that its encoding uses
          a maximum of three bytes for multi-byte characters. (Old
          tables that previously used `utf8' will be reported as using
          `utf8mb3' after an in-place upgrade to MySQL 6.0, but
          otherwise work as before.)

        * The new `utf8' character set in MySQL 6.0 is similar to
          `utf8mb3', but its encoding allows up to four bytes per
          character to enable support for supplementary characters.

        * The `ucs2' character set is essentially unchanged except for
          the inclusion of some newer BMP characters.

     In most respects, upgrading from MySQL 5.1 to 6.0 should present
     few problems with regard to Unicode usage, although there are some
     potential areas of incompatibility. Some examples:

        * For the variable-length character data types (*Note
          `VARCHAR': char. and the *Note `TEXT': blob. types), the
          maximum length in characters for `utf8' columns is less in
          MySQL 6.0 than previously.

        * For all character data types (*Note `CHAR': char, *Note
          `VARCHAR': char, and the *Note `TEXT': blob. types), the
          maximum number of characters for `utf8' columns that can be
          indexed is less in MySQL 6.0 than previously.

     Consequently, if you want to upgrade tables from the old `utf8'
     (now `utf8mb3') to the current `utf8', it may be necessary to
     change some column or index definitions.

     For additional details about the new Unicode character sets and
     potential incompatibilities, see *Note charset-unicode::, and
     *Note charset-unicode-upgrading::.

     If you use events, a known issue is that if you upgrade from MySQL
     5.1 to 6.0.4 though 6.0.6, the event scheduler will not work, even
     after you run *Note `mysql_upgrade': mysql-upgrade. (This is an
     issue only for an upgrade, not for a new installation of MySQL
     6.0.x.) As of MySQL 6.0.7, *Note `mysql_upgrade': mysql-upgrade.
     handles upgrading the system tables properly. If you upgrade to
     6.0.4 through 6.0.6, you can work around this upgrading problem by
     using these instructions:

       1. In MySQL 5.1, before upgrading, create a dump file containing
          your `mysql.event' table:

               shell> mysqldump -uroot -p mysql event > event.sql

       2. Stop the server, upgrade to MySQL 6.0, and start the server.

       3. Recreate the `mysql.event' table using the dump file:

               shell> mysql -uroot -p mysql < event.sql

       4. Run *Note `mysql_upgrade': mysql-upgrade. to upgrade the
          other system tables in the `mysql' database:

               shell> mysql_upgrade -uroot -p

       5. Restart the server. The event scheduler should run normally.

   * *Incompatible change*: As of MySQL 6.0.3, *Note `DROP TABLE':
     drop-table.  is allowed only if you have acquired a `WRITE' lock
     with *Note `LOCK TABLES': lock-tables, or if you hold no locks, or
     if the table is a `TEMPORARY' table.

     Previously, if other tables were locked, you could drop a table
     with a read lock or no lock, which could lead to deadlocks between
     clients. The new stricter behavior means that some usage scenarios
     will fail when previously they did not.

*SQL Changes:*

   * *Incompatible change:* Several changes were made to the processing
     of multiple-table *Note `DELETE': delete.  statements:

        * Statements could not perform cross-database deletes unless
          the tables were referred to without using aliases. This
          limitation has been lifted and table aliases now are allowed.

        * Previously, alias declarations could be given for tables
          elsewhere than in the TABLE_REFERENCES part of the syntax.
          This could lead to ambiguous statements that have unexpected
          results such as deleting rows from the wrong table. Example:

               DELETE FROM t1 AS a2 USING t1 AS a1 INNER JOIN t2 AS a2;

          Now alias declarations can be declared only in the
          TABLE_REFERENCES part.  Elsewhere in the statement, alias
          references are allowed but not alias declarations.

        * Alias resolution was improved so that it is no longer
          possible to have inconsistent or ambiguous aliases for tables.

     Statements containing alias constructs that are no longer allowed
     must be rewritten.


File: manual.info,  Node: downgrading,  Next: checking-index-changes,  Prev: upgrade,  Up: upgrade-downgrade

2.11.2 Downgrading MySQL
------------------------

* Menu:

* downgrading-to-5-0::           Downgrading to MySQL 5.0

This section describes what you should do to downgrade to an older
MySQL version in the unlikely case that the previous version worked
better than the new one.

If you are downgrading within the same release series (for example,
from 5.1.13 to 5.1.12) the general rule is that you just have to
install the new binaries on top of the old ones. There is no need to do
anything with the databases. As always, however, it is always a good
idea to make a backup.

The following items form a checklist of things you should do whenever
you perform a downgrade:

   * Read the upgrading section for the release series from which you
     are downgrading to be sure that it does not have any features you
     really need. See *Note upgrade::.

   * If there is a downgrading section for that version, you should
     read that as well.

   * To see which new features were added between the version to which
     you are downgrading and your current version, see the change logs
     (*Note news::).

   * Check *Note checking-index-changes::, to see whether changes to
     character sets or collations were made between your current
     version of MySQL and the version to which you are downgrading. If
     so and these changes affect your table indexes, you will need to
     rebuild the affected indexes using the instructions in *Note
     rebuilding-tables::.

In most cases, you can move the MySQL format files and data files
between different versions on the same architecture as long as you stay
within versions for the same release series of MySQL.

If you downgrade from one release series to another, there may be
incompatibilities in table storage formats. In this case, use *Note
`mysqldump': mysqldump. to dump your tables before downgrading. After
downgrading, reload the dump file using *Note `mysql': mysql. or *Note
`mysqlimport': mysqlimport. to re-create your tables. For examples, see
*Note copying-databases::.

A typical symptom of a downward-incompatible table format change when
you downgrade is that you cannot open tables. In that case, use the
following procedure:

  1. Stop the older MySQL server that you are downgrading to.

  2. Restart the newer MySQL server you are downgrading from.

  3. Dump any tables that were inaccessible to the older server by
     using *Note `mysqldump': mysqldump. to create a dump file.

  4. Stop the newer MySQL server and restart the older one.

  5. Reload the dump file into the older server. Your tables should be
     accessible.

It might also be the case that the structure of the system tables in
the `mysql' database has changed and that downgrading introduces some
loss of functionality or requires some adjustments. Here are some
examples:

   * Trigger creation requires the `TRIGGER' privilege as of MySQL 5.1.
     In MySQL 5.0, there is no `TRIGGER' privilege and `SUPER' is
     required instead. If you downgrade from MySQL 5.1 to 5.0, you will
     need to give the `SUPER' privilege to those accounts that had the
     `TRIGGER' privilege in 5.1.

   * Triggers were added in MySQL 5.0, so if you downgrade from 5.0 to
     4.1, you cannot use triggers at all.


File: manual.info,  Node: downgrading-to-5-0,  Prev: downgrading,  Up: downgrading

2.11.2.1 Downgrading to MySQL 5.0
.................................

When downgrading to MySQL 5.0 from MySQL 5.1 or a later version, you
should keep in mind the following issues relating to features found in
MySQL 5.1 and later, but not in MySQL 5.0:

   * Event Scheduler

     MySQL 5.0 does not support scheduled events. If your databases
     contain scheduled event definitions, you should prevent them from
     being dumped when you use *Note `mysqldump': mysqldump. by using
     the `--skip-events' option. (See *Note mysqldump::.)

   * Partitioning

     MySQL 5.0 does not support user-defined partitioning. If a table
     was created as a partitioned table in 5.1 (or if an table created
     in a previous version of MySQL was altered to include partitions
     after an upgrade to 5.1), the table is accessible after downgrade
     only if you do one of the following:

        * Export the table using *Note `mysqldump': mysqldump. and then
          drop it in MySQL 5.1; import the table again following the
          downgrade to MySQL 5.0.

        * Prior to the downgrade, remove the table's partitioning using
          `ALTER TABLE TABLE_NAME REMOVE PARTITIONING'.


File: manual.info,  Node: checking-index-changes,  Next: rebuilding-tables,  Prev: downgrading,  Up: upgrade-downgrade

2.11.3 Checking Whether Table Indexes Must Be Rebuilt
-----------------------------------------------------

A binary upgrade or downgrade is one that installs one version of MySQL
`in place' over an existing version, without dumping and reloading
tables:

  1. Stop the server for the existing version if it is running.

  2. Install a different version of MySQL. This is an upgrade if the
     new version is higher than the original version, a downgrade if
     the version is lower.

  3. Start the server for the new version.

In many cases, the tables from the previous version of MySQL can be
used without change by the new version. However, sometimes
modifications are made to the handling of character sets or collations
that change the character sort order, which causes the ordering of
entries in any index that uses an affected character set or collation
to be incorrect. Such changes result in several possible problems:

   * Comparison results that differ from previous results

   * Inability to find some index values due to misordered index entries

   * Misordered `ORDER BY' results

   * Tables that *Note `CHECK TABLE': check-table.  reports as being in
     need of repair

The solution to these problems is to rebuild any indexes that use an
affected character set or collation, either by dropping and re-creating
the indexes, or by dumping and reloading the entire table. For
information about rebuilding indexes, see *Note rebuilding-tables::.

To check whether a table has indexes that must be rebuilt, consult the
following list. It indicates which versions of MySQL introduced
character set or collation changes that require indexes to be rebuilt.
Each entry indicates the version in which the change occurred and the
character sets or collations that the change affects. If the change is
associated with a particular bug report, the bug number is given.

The list applies both for binary upgrades and downgrades. For example,
Bug#29461 (http://bugs.mysql.com/29461) was fixed in MySQL 5.0.48, so
it applies to upgrades from versions older than 5.0.48 to 5.0.48 or
newer, and also to downgrades from 5.0.48 or newer to versions older
than 5.0.58.

If you have tables with indexes that are affected, rebuild the indexes
using the instructions given in *Note rebuilding-tables::.

In many cases, you can use *Note `CHECK TABLE ... FOR UPDATE':
check-table. to identify tables for which index rebuilding is required.
(It will report: `Table upgrade required.  Please do "REPAIR TABLE
`tbl_name`" to fix it!') In these cases, you can also use *Note
`mysqlcheck --check-upgrade': mysqlcheck. or *Note `mysql_upgrade':
mysql-upgrade, which execute *Note `CHECK TABLE': check-table.
However, the use of *Note `CHECK TABLE': check-table.  applies only
after upgrades, not downgrades. Also, *Note `CHECK TABLE': check-table.
is not applicable to all storage engines. For details about which
storage engines *Note `CHECK TABLE': check-table. supports, see *Note
check-table::.

Changes that cause index rebuilding to be necessary:

   * MySQL 5.0.48 (Bug#29461 (http://bugs.mysql.com/29461))

     Affects indexes for columns that use any of these character sets:
     `eucjpms', `euc_kr', `gb2312', `latin7', `macce', `ujis'

     Affected tables can be detected by *Note `CHECK TABLE ... FOR
     UPDATE': check-table. as of MySQL 5.1.29, 6.0.8 (see Bug#39585
     (http://bugs.mysql.com/39585)).

   * MySQL 5.0.48 (Bug#27562 (http://bugs.mysql.com/27562))

     Affects indexes that use the `ascii_general_ci' collation for
     columns that contain any of these characters: `'`'' GRAVE ACCENT,
     `'['' LEFT SQUARE BRACKET, `'\'' REVERSE SOLIDUS, `']'' RIGHT
     SQUARE BRACKET, `'~'' TILDE

     Affected tables can be detected by *Note `CHECK TABLE ... FOR
     UPDATE': check-table. as of MySQL 5.1.29, 6.0.8 (see Bug#39585
     (http://bugs.mysql.com/39585)).

   * MySQL 5.1.21 (Bug#29461 (http://bugs.mysql.com/29461))

     Affects indexes for columns that use any of these character sets:
     `eucjpms', `euc_kr', `gb2312', `latin7', `macce', `ujis'

     Affected tables can be detected by *Note `CHECK TABLE ... FOR
     UPDATE': check-table. as of MySQL 5.1.29, 6.0.8 (see Bug#39585
     (http://bugs.mysql.com/39585)).

   * MySQL 5.1.23 (Bug#27562 (http://bugs.mysql.com/27562))

     Affects indexes that use the `ascii_general_ci' collation for
     columns that contain any of these characters: `'`'' GRAVE ACCENT,
     `'['' LEFT SQUARE BRACKET, `'\'' REVERSE SOLIDUS, `']'' RIGHT
     SQUARE BRACKET, `'~'' TILDE

     Affected tables can be detected by *Note `CHECK TABLE ... FOR
     UPDATE': check-table. as of MySQL 5.1.29, 6.0.8 (see Bug#39585
     (http://bugs.mysql.com/39585)).

   * MySQL 5.1.24 (Bug#27877 (http://bugs.mysql.com/27877))

     Affects indexes that use the `utf8_general_ci' or
     `ucs2_general_ci' collation for columns that contain `'ss'' LATIN
     SMALL LETTER SHARP S (German).

     Affected tables can be detected by *Note `CHECK TABLE ... FOR
     UPDATE': check-table. as of MySQL 5.1.30, 6.0.8 (see Bug#40053
     (http://bugs.mysql.com/40053)).

   * * MySQL 6.0.1 (WL#3664)

     Affects indexes that use the `latin2_czech_cs collation'.

     Affected tables can be detected by *Note `CHECK TABLE ... FOR
     UPDATE': check-table. as of MySQL 6.0.9 (see Bug#40054
     (http://bugs.mysql.com/40054)).

     MySQL 6.0.5 (Bug#33452 (http://bugs.mysql.com/33452))

     Affects indexes that use the `latin2_czech_cs collation'.

     Affected tables can be detected by *Note `CHECK TABLE ... FOR
     UPDATE': check-table. as of MySQL 6.0.9 (see Bug#40054
     (http://bugs.mysql.com/40054)).

   * MySQL 6.0.5 (Bug#27877 (http://bugs.mysql.com/27877))

     Affects indexes that use the `utf8_general_ci' or
     `ucs2_general_ci' collation for columns that contain `'ss'' LATIN
     SMALL LETTER SHARP S (German).

     Affected tables can be detected by *Note `CHECK TABLE ... FOR
     UPDATE': check-table. as of MySQL 6.0.8 (see Bug#40053
     (http://bugs.mysql.com/40053)).

   * MySQL 6.0.6 (Bug#25420 (http://bugs.mysql.com/25420))

     Affects indexes for columns that use the following collations, if
     the columns contain the indicated characters: `big5_chinese_ci':
     `'~'' TILDE or `'`'' GRAVE ACCENT; `cp866_general_ci': `j' LATIN
     SMALL LETTER J; `gb2312_chinese_ci': `'~'' TILDE;
     `gbk_chinese_ci': `'~'' TILDE

     Affected tables can be detected by *Note `CHECK TABLE ... FOR
     UPDATE': check-table. as of MySQL 6.0.9 (see Bug#40054
     (http://bugs.mysql.com/40054)).


File: manual.info,  Node: rebuilding-tables,  Next: copying-databases,  Prev: checking-index-changes,  Up: upgrade-downgrade

2.11.4 Rebuilding Tables or Table Indexes
-----------------------------------------

This section describes how to rebuild a table. This can be necessitated
by changes to MySQL such as how data types are handled or changes to
character set handling. For example, an error in a collation might have
been corrected, necessitating a table rebuild to rebuild the indexes
for character columns that use the collation. Methods for rebuilding a
table include dumping and reloading it, or using *Note `ALTER TABLE':
alter-table.

*Note*:

If you are rebuilding tables because a different version of MySQL will
not handle them after a binary upgrade or downgrade, you must use the
dump-and-reload method. Dump the tables _before_ upgrading or
downgrading (using your original version of MySQL), and reload the
tables _after_ upgrading or downgrading (after installing the new
version).

If you use the dump-and-reload method of rebuilding tables only for the
purpose of rebuilding indexes, you can perform the dump either before
or after upgrading or downgrading.  Reloading still must be done
afterward.

For the examples in this section, suppose that a table `t1' is defined
like this:

     CREATE TABLE t1 (
       c1 VARCHAR(10) CHARACTER SET macce,
       c2 TEXT CHARACTER SET ujis,
       c3 VARCHAR(20) CHARACTER SET latin1,
       PRIMARY KEY (c1),
       INDEX (c2(20))
     );

To re-create a table by dumping and reloading it, use *Note
`mysqldump': mysqldump. to create a dump file and *Note `mysql': mysql.
to reload the file:

     shell> mysqldump DB_NAME t1 > dump.sql
     shell> mysql DB_NAME < dump.sql

To recreate all the tables in a single database, specify the database
name without any following table name:

     shell> mysqldump DB_NAME > dump.sql
     shell> mysql DB_NAME < dump.sql

To recreate all tables in all databases, use the `--all-databases'
option:

     shell> mysqldump --all-databases > dump.sql
     shell> mysql < dump.sql

To rebuild a table with *Note `ALTER TABLE': alter-table, use a
statement that `changes' the table to use the storage engine that it
already has. For example, if `t1' is a `MyISAM' table, use this
statement:

     mysql> ALTER TABLE t1 ENGINE = MyISAM;

If you are not sure which storage engine is used for the table, use
*Note `SHOW CREATE TABLE': show-create-table. to display the table
definition.


File: manual.info,  Node: copying-databases,  Prev: rebuilding-tables,  Up: upgrade-downgrade

2.11.5 Copying MySQL Databases to Another Machine
-------------------------------------------------

You can copy the `.frm', `.MYI', and `.MYD' files for `MyISAM' tables
between different architectures that support the same floating-point
format.  (MySQL takes care of any byte-swapping issues.) See *Note
myisam-storage-engine::.

In cases where you need to transfer databases between different
architectures, you can use *Note `mysqldump': mysqldump. to create a
file containing SQL statements. You can then transfer the file to the
other machine and feed it as input to the *Note `mysql': mysql. client.

Use *Note `mysqldump --help': mysqldump. to see what options are
available.

The easiest (although not the fastest) way to move a database between
two machines is to run the following commands on the machine on which
the database is located:

     shell> mysqladmin -h 'OTHER_HOSTNAME' create DB_NAME
     shell> mysqldump DB_NAME | mysql -h 'OTHER_HOSTNAME' DB_NAME

If you want to copy a database from a remote machine over a slow
network, you can use these commands:

     shell> mysqladmin create DB_NAME
     shell> mysqldump -h 'OTHER_HOSTNAME' --compress DB_NAME | mysql DB_NAME

You can also store the dump in a file, transfer the file to the target
machine, and then load the file into the database there.  For example,
you can dump a database to a compressed file on the source machine like
this:

     shell> mysqldump --quick DB_NAME | gzip > DB_NAME.gz

Transfer the file containing the database contents to the target
machine and run these commands there:

     shell> mysqladmin create DB_NAME
     shell> gunzip < DB_NAME.gz | mysql DB_NAME

You can also use *Note `mysqldump': mysqldump. and *Note `mysqlimport':
mysqlimport. to transfer the database. For large tables, this is much
faster than simply using *Note `mysqldump': mysqldump. In the following
commands, DUMPDIR represents the full path name of the directory you
use to store the output from *Note `mysqldump': mysqldump.

First, create the directory for the output files and dump the database:

     shell> mkdir DUMPDIR
     shell> mysqldump --tab=DUMPDIR DB_NAME

Then transfer the files in the DUMPDIR directory to some corresponding
directory on the target machine and load the files into MySQL there:

     shell> mysqladmin create DB_NAME           # create database
     shell> cat DUMPDIR/*.sql | mysql DB_NAME   # create tables in database
     shell> mysqlimport DB_NAME DUMPDIR/*.txt   # load data into tables

Do not forget to copy the `mysql' database because that is where the
grant tables are stored. You might have to run commands as the MySQL
`root' user on the new machine until you have the `mysql' database in
place.

After you import the `mysql' database on the new machine, execute *Note
`mysqladmin flush-privileges': mysqladmin. so that the server reloads
the grant table information.


File: manual.info,  Node: operating-system-specific-notes,  Next: environment-variables,  Prev: upgrade-downgrade,  Up: installing

2.12 Operating System-Specific Notes
====================================

* Menu:

* linux::                        Linux Notes
* mac-os-x::                     Mac OS X Notes
* solaris::                      Solaris Notes
* bsd-notes::                    BSD Notes
* other-unix-notes::             Other Unix Notes


File: manual.info,  Node: linux,  Next: mac-os-x,  Prev: operating-system-specific-notes,  Up: operating-system-specific-notes

2.12.1 Linux Notes
------------------

* Menu:

* linux-os::                     Linux Operating System Notes
* binary-notes-linux::           Linux Binary Distribution Notes
* source-notes-linux::           Linux Source Distribution Notes
* linux-post-install::           Linux Post-Installation Notes
* linux-x86::                    Linux x86 Notes
* linux-sparc::                  Linux SPARC Notes
* linux-alpha::                  Linux Alpha Notes
* linux-powerpc::                Linux PowerPC Notes
* linux-mips::                   Linux MIPS Notes
* linux-ia-64::                  Linux IA-64 Notes
* selinux::                      SELinux Notes

This section discusses issues that have been found to occur on Linux.
The first few subsections describe general operating system-related
issues, problems that can occur when using binary or source
distributions, and post-installation issues. The remaining subsections
discuss problems that occur with Linux on specific platforms.

Note that most of these problems occur on older versions of Linux. If
you are running a recent version, you may see none of them.


File: manual.info,  Node: linux-os,  Next: binary-notes-linux,  Prev: linux,  Up: linux

2.12.1.1 Linux Operating System Notes
.....................................

MySQL needs at least Linux version 2.0.

*Warning*:

We have seen some strange problems with Linux 2.2.14 and MySQL on SMP
systems. We also have reports from some MySQL users that they have
encountered serious stability problems using MySQL with kernel 2.2.14.
If you are using this kernel, you should upgrade to 2.2.19 (or newer)
or to a 2.4 kernel. If you have a multiple-CPU box, you should seriously
consider using 2.4 because it gives you a significant speed boost. Your
system should be more stable.

When using LinuxThreads, you should see a minimum of three *Note
`mysqld': mysqld. processes running. These are in fact threads. There
is one thread for the LinuxThreads manager, one thread to handle
connections, and one thread to handle alarms and signals.


File: manual.info,  Node: binary-notes-linux,  Next: source-notes-linux,  Prev: linux-os,  Up: linux

2.12.1.2 Linux Binary Distribution Notes
........................................

The Linux-Intel binary and RPM releases of MySQL are configured for the
highest possible speed. We are always trying to use the fastest stable
compiler available.

The binary release is linked with `-static', which means you do not
normally need to worry about which version of the system libraries you
have. You need not install LinuxThreads, either. A program linked with
`-static' is slightly larger than a dynamically linked program, but
also slightly faster (3-5%). However, one problem with a statically
linked program is that you can't use user-defined functions (UDFs). If
you are going to write or use UDFs (this is something for C or C++
programmers only), you must compile MySQL yourself using dynamic
linking.

A known issue with binary distributions is that on older Linux systems
that use `libc' (such as Red Hat 4.x or Slackware), you get some
(non-fatal) issues with host name resolution. If your system uses
`libc' rather than `glibc2', you probably will encounter some
difficulties with host name resolution and `getpwnam()'. This happens
because `glibc' (unfortunately) depends on some external libraries to
implement host name resolution and `getpwent()', even when compiled with
`-static'. These problems manifest themselves in two ways:

   * You may see the following error message when you run *Note
     `mysql_install_db': mysql-install-db.:

          Sorry, the host 'XXXX' could not be looked up

     You can deal with this by executing *Note `mysql_install_db
     --force': mysql-install-db, which does not execute the *Note
     `resolveip': resolveip. test in *Note `mysql_install_db':
     mysql-install-db. The downside is that you cannot use host names
     in the grant tables: except for `localhost', you must use IP
     numbers instead. If you are using an old version of MySQL that
     does not support `--force', you must manually remove the
     `resolveip' test in *Note `mysql_install_db': mysql-install-db.
     using a text editor.

   * You also may see the following error when you try to run *Note
     `mysqld': mysqld. with the `--user' option:

          getpwnam: No such file or directory

     To work around this problem, start *Note `mysqld': mysqld. by
     using the `su' command rather than by specifying the `--user'
     option. This causes the system itself to change the user ID of the
     *Note `mysqld': mysqld. process so that *Note `mysqld': mysqld.
     need not do so.

Another solution, which solves both problems, is not to use a binary
distribution. Obtain a MySQL source distribution (in RPM or `tar.gz'
format) and install that instead.

On some Linux 2.2 versions, you may get the error `Resource temporarily
unavailable' when clients make a great many new connections to a *Note
`mysqld': mysqld. server over TCP/IP. The problem is that Linux has a
delay between the time that you close a TCP/IP socket and the time that
the system actually frees it.  There is room for only a finite number
of TCP/IP slots, so you encounter the resource-unavailable error if
clients attempt too many new TCP/IP connections over a short period of
time.  For example, you may see the error when you run the MySQL
`test-connect' benchmark over TCP/IP.

We have inquired about this problem a few times on different Linux
mailing lists but have never been able to find a suitable resolution.
The only known `fix' is for clients to use persistent connections, or,
if you are running the database server and clients on the same machine,
to use Unix socket file connections rather than TCP/IP connections.


File: manual.info,  Node: source-notes-linux,  Next: linux-post-install,  Prev: binary-notes-linux,  Up: linux

2.12.1.3 Linux Source Distribution Notes
........................................

The following notes regarding `glibc' apply only to the situation when
you build MySQL yourself. If you are running Linux on an x86 machine,
in most cases it is much better for you to use our binary. We link our
binaries against the best patched version of `glibc' we can find and
with the best compiler options, in an attempt to make it suitable for a
high-load server. For a typical user, even for setups with a lot of
concurrent connections or tables exceeding the 2GB limit, our binary is
the best choice in most cases. After reading the following text, if you
are in doubt about what to do, try our binary first to determine
whether it meets your needs. If you discover that it is not good enough,
you may want to try your own build. In that case, we would appreciate a
note about it so that we can build a better binary next time.

MySQL uses LinuxThreads on Linux. If you are using an old Linux version
that doesn't have `glibc2', you must install LinuxThreads before trying
to compile MySQL. You can obtain LinuxThreads from
`http://dev.mysql.com/downloads/os-linux.html'.

Note that `glibc' versions before and including version 2.1.1 have a
fatal bug in `pthread_mutex_timedwait()' handling, which is used when
*Note `INSERT DELAYED': insert-delayed.  statements are issued. We
recommend that you not use *Note `INSERT DELAYED': insert-delayed.
before upgrading `glibc'.

Note that Linux kernel and the LinuxThread library can by default
handle a maximum of 1,024 threads. If you plan to have more than 1,000
concurrent connections, you need to make some changes to LinuxThreads,
as follows:

   * Increase `PTHREAD_THREADS_MAX' in
     `sysdeps/unix/sysv/linux/bits/local_lim.h' to 4096 and decrease
     `STACK_SIZE' in `linuxthreads/internals.h' to 256KB.  The paths
     are relative to the root of `glibc'. (Note that MySQL is not stable
     with 600-1000 connections if `STACK_SIZE' is the default of 2MB.)

   * Recompile LinuxThreads to produce a new `libpthread.a' library,
     and relink MySQL against it.

There is another issue that greatly hurts MySQL performance, especially
on SMP systems. The mutex implementation in LinuxThreads in `glibc' 2.1
is very poor for programs with many threads that hold the mutex only
for a short time. This produces a paradoxical result: If you link MySQL
against an unmodified LinuxThreads, removing processors from an SMP
actually improves MySQL performance in many cases.  We have made a
patch available for `glibc' 2.1.3 to correct this behavior
(`http://dev.mysql.com/Downloads/Linux/linuxthreads-2.1-patch').

With `glibc' 2.2.2, MySQL uses the adaptive mutex, which is much better
than even the patched one in `glibc' 2.1.3. Be warned, however, that
under some conditions, the current mutex code in `glibc' 2.2.2
overspins, which hurts MySQL performance. The likelihood that this
condition occurs can be reduced by re-nicing the *Note `mysqld':
mysqld. process to the highest priority. We have also been able to
correct the overspin behavior with a patch, available at
`http://dev.mysql.com/Downloads/Linux/linuxthreads-2.2.2.patch'.  It
combines the correction of overspin, maximum number of threads, and
stack spacing all in one. You need to apply it in the `linuxthreads'
directory with `patch -p0 </tmp/linuxthreads-2.2.2.patch'. We hope it is
included in some form in future releases of `glibc' 2.2. In any case,
if you link against `glibc' 2.2.2, you still need to correct
`STACK_SIZE' and `PTHREAD_THREADS_MAX'. We hope that the defaults is
corrected to some more acceptable values for high-load MySQL setup in
the future, so that the commands needed to produce your own build can
be reduced to `./configure; make; make install'.

We recommend that you use these patches to build a special static
version of `libpthread.a' and use it only for statically linking
against MySQL. We know that these patches are safe for MySQL and
significantly improve its performance, but we cannot say anything about
their effects on other applications. If you link other applications that
require LinuxThreads against the patched static version of the library,
or build a patched shared version and install it on your system, you do
so at your own risk.

If you experience any strange problems during the installation of
MySQL, or with some common utilities hanging, it is very likely that
they are either library or compiler related. If this is the case, using
our binary resolves them.

If you link your own MySQL client programs, you may see the following
error at runtime:

     ld.so.1: fatal: libmysqlclient.so.#:
     open failed: No such file or directory

This problem can be avoided by one of the following methods:

   * Link clients with the `-Wl,r/full/path/to/libmysqlclient.so' flag
     rather than with `-Lpath').

   * Copy `libmysqclient.so' to `/usr/lib'.

   * Add the path name of the directory where `libmysqlclient.so' is
     located to the `LD_RUN_PATH' environment variable before running
     your client.

If you are using the Fujitsu compiler (`fcc/FCC'), you may have some
problems compiling MySQL because the Linux header files are very `gcc'
oriented. The following `configure' line should work with `fcc/FCC':

     CC=fcc CFLAGS="-O -K fast -K lib -K omitfp -Kpreex -D_GNU_SOURCE \
         -DCONST=const -DNO_STRTOLL_PROTO" \
     CXX=FCC CXXFLAGS="-O -K fast -K lib \
         -K omitfp -K preex --no_exceptions --no_rtti -D_GNU_SOURCE \
         -DCONST=const -Dalloca=__builtin_alloca -DNO_STRTOLL_PROTO \
         '-D_EXTERN_INLINE=static __inline'" \
     ./configure \
         --prefix=/usr/local/mysql --enable-assembler \
         --with-mysqld-ldflags=-all-static --disable-shared \
         --with-low-memory


File: manual.info,  Node: linux-post-install,  Next: linux-x86,  Prev: source-notes-linux,  Up: linux

2.12.1.4 Linux Post-Installation Notes
......................................

*Note `mysql.server': mysql-server. can be found in the `support-files'
directory under the MySQL installation directory or in a MySQL source
tree. You can install it as `/etc/init.d/mysql' for automatic MySQL
startup and shutdown. See *Note automatic-start::.

If MySQL cannot open enough files or connections, it may be that you
have not configured Linux to handle enough files.

In Linux 2.2 and onward, you can check the number of allocated file
handles as follows:

     shell> cat /proc/sys/fs/file-max
     shell> cat /proc/sys/fs/dquot-max
     shell> cat /proc/sys/fs/super-max

If you have more than 16MB of memory, you should add something like the
following to your init scripts (for example, `/etc/init.d/boot.local'
on SuSE Linux):

     echo 65536 > /proc/sys/fs/file-max
     echo 8192 > /proc/sys/fs/dquot-max
     echo 1024 > /proc/sys/fs/super-max

You can also run the `echo' commands from the command line as `root',
but these settings are lost the next time your computer restarts.

Alternatively, you can set these parameters on startup by using the
`sysctl' tool, which is used by many Linux distributions (including
SuSE Linux 8.0 and later).  Put the following values into a file named
`/etc/sysctl.conf':

     # Increase some values for MySQL
     fs.file-max = 65536
     fs.dquot-max = 8192
     fs.super-max = 1024

You should also add the following to `/etc/my.cnf':

     [mysqld_safe]
     open-files-limit=8192

This should allow the server a limit of 8,192 for the combined number
of connections and open files.

The `STACK_SIZE' constant in LinuxThreads controls the spacing of
thread stacks in the address space. It needs to be large enough so that
there is plenty of room for each individual thread stack, but small
enough to keep the stack of some threads from running into the global
*Note `mysqld': mysqld. data. Unfortunately, as we have experimentally
discovered, the Linux implementation of `mmap()' successfully unmaps a
mapped region if you ask it to map out an address currently in use,
zeroing out the data on the entire page instead of returning an error.
So, the safety of *Note `mysqld': mysqld. or any other threaded
application depends on the `gentlemanly' behavior of the code that
creates threads. The user must take measures to make sure that the
number of running threads at any given time is sufficiently low for
thread stacks to stay away from the global heap. With *Note `mysqld':
mysqld, you should enforce this behavior by setting a reasonable value
for the `max_connections' variable.

If you build MySQL yourself, you can patch LinuxThreads for better
stack use. See *Note source-notes-linux::. If you do not want to patch
LinuxThreads, you should set `max_connections' to a value no higher
than 500. It should be even less if you have a large key buffer, large
heap tables, or some other things that make *Note `mysqld': mysqld.
allocate a lot of memory, or if you are running a 2.2 kernel with a 2GB
patch. If you are using our binary or RPM version, you can safely set
`max_connections' at 1500, assuming no large key buffer or heap tables
with lots of data.  The more you reduce `STACK_SIZE' in LinuxThreads
the more threads you can safely create. We recommend values between
128KB and 256KB.

If you use a lot of concurrent connections, you may suffer from a
`feature' in the 2.2 kernel that attempts to prevent fork bomb attacks
by penalizing a process for forking or cloning a child. This causes
MySQL not to scale well as you increase the number of concurrent
clients. On single-CPU systems, we have seen this manifest as very slow
thread creation; it may take a long time to connect to MySQL (as long
as one minute), and it may take just as long to shut it down. On
multiple-CPU systems, we have observed a gradual drop in query speed as
the number of clients increases. In the process of trying to find a
solution, we have received a kernel patch from one of our users who
claimed it helped for his site. This patch is available at
`http://dev.mysql.com/Downloads/Patches/linux-fork.patch'.  We have
done rather extensive testing of this patch on both development and
production systems. It has significantly improved MySQL performance
without causing any problems and we recommend it to our users who still
run high-load servers on 2.2 kernels.

This issue has been fixed in the 2.4 kernel, so if you are not
satisfied with the current performance of your system, rather than
patching your 2.2 kernel, it might be easier to upgrade to 2.4. On SMP
systems, upgrading also gives you a nice SMP boost in addition to
fixing the fairness bug.

We have tested MySQL on the 2.4 kernel on a two-CPU machine and found
MySQL scales _much_ better. There was virtually no slowdown on query
throughput all the way up to 1,000 clients, and the MySQL scaling
factor (computed as the ratio of maximum throughput to the throughput
for one client) was 180%. We have observed similar results on a
four-CPU system: Virtually no slowdown as the number of clients was
increased up to 1,000, and a 300% scaling factor.  Based on these
results, for a high-load SMP server using a 2.2 kernel, we definitely
recommend upgrading to the 2.4 kernel at this point.

We have discovered that it is essential to run the *Note `mysqld':
mysqld. process with the highest possible priority on the 2.4 kernel to
achieve maximum performance.  This can be done by adding a `renice -20
$$' command to *Note `mysqld_safe': mysqld-safe. In our testing on a
four-CPU machine, increasing the priority resulted in a 60% throughput
increase with 400 clients.

We are currently also trying to collect more information on how well
MySQL performs with a 2.4 kernel on four-way and eight-way systems. If
you have access such a system and have done some benchmarks, please
send an email message to <benchmarks@mysql.com> with the results. We
will review them for inclusion in the manual.

If you see a dead *Note `mysqld': mysqld. server process with `ps',
this usually means that you have found a bug in MySQL or you have a
corrupted table. See *Note crashing::.

To get a core dump on Linux if *Note `mysqld': mysqld. dies with a
`SIGSEGV' signal, you can start *Note `mysqld': mysqld. with the
`--core-file' option. Note that you also probably need to raise the
core file size by adding `ulimit -c 1000000' to *Note `mysqld_safe':
mysqld-safe. or starting *Note `mysqld_safe': mysqld-safe. with
`--core-file-size=1000000'.  See *Note mysqld-safe::.


File: manual.info,  Node: linux-x86,  Next: linux-sparc,  Prev: linux-post-install,  Up: linux

2.12.1.5 Linux x86 Notes
........................

MySQL requires `libc' 5.4.12 or newer. It is known to work with `libc'
5.4.46.  `glibc' 2.0.6 and later should also work.  There have been
some problems with the `glibc' RPMs from Red Hat, so if you have
problems, check whether there are any updates. The `glibc' 2.0.7-19 and
2.0.7-29 RPMs are known to work.

If you are using Red Hat 8.0 or a new `glibc' 2.2.x library, you may
see *Note `mysqld': mysqld. die in `gethostbyaddr()'. This happens
because the new `glibc' library requires a stack size greater than
128KB for this call. To fix the problem, start *Note `mysqld': mysqld.
with the `--thread-stack=192K' option.  (Use `-O thread_stack=192K'
before MySQL 4.)  This stack size is the default on MySQL 4.0.10 and
above, so you should not see the problem.

If you are using `gcc' 3.0 and above to compile MySQL, you must install
the `libstdc++v3' library before compiling MySQL; if you don't do this,
you get an error about a missing `__cxa_pure_virtual' symbol during
linking.

On some older Linux distributions, `configure' may produce an error
like this:

     Syntax error in sched.h. Change _P to __P in the
     /usr/include/sched.h file.
     See the Installation chapter in the Reference Manual.

Just do what the error message says. Add an extra underscore to the
`_P' macro name that has only one underscore, and then try again.

You may get some warnings when compiling. Those shown here can be
ignored:

     mysqld.cc -o objs-thread/mysqld.o
     mysqld.cc: In function `void init_signals()':
     mysqld.cc:315: warning: assignment of negative value `-1' to
     `long unsigned int'
     mysqld.cc: In function `void * signal_hand(void *)':
     mysqld.cc:346: warning: assignment of negative value `-1' to
     `long unsigned int'

If *Note `mysqld': mysqld. always dumps core when it starts, the
problem may be that you have an old `/lib/libc.a'. Try renaming it, and
then remove `sql/mysqld' and do a new `make install' and try again.
This problem has been reported on some Slackware installations.

If you get the following error when linking *Note `mysqld': mysqld, it
means that your `libg++.a' is not installed correctly:

     /usr/lib/libc.a(putc.o): In function `_IO_putc':
     putc.o(.text+0x0): multiple definition of `_IO_putc'

You can avoid using `libg++.a' by running `configure' like this:

     shell> CXX=gcc ./configure


File: manual.info,  Node: linux-sparc,  Next: linux-alpha,  Prev: linux-x86,  Up: linux

2.12.1.6 Linux SPARC Notes
..........................

In some implementations, `readdir_r()' is broken. The symptom is that
the *Note `SHOW DATABASES': show-databases. statement always returns an
empty set.  This can be fixed by removing `HAVE_READDIR_R' from
`config.h' after configuring and before compiling.


File: manual.info,  Node: linux-alpha,  Next: linux-powerpc,  Prev: linux-sparc,  Up: linux

2.12.1.7 Linux Alpha Notes
..........................

We have tested MySQL 6.0 on Alpha with our benchmarks and test suite,
and it appears to work well.

We currently build the MySQL binary packages on SuSE Linux 7.0 for AXP,
kernel 2.4.4-SMP, Compaq C compiler (V6.2-505) and Compaq C++ compiler
(V6.3-006) on a Compaq DS20 machine with an Alpha EV6 processor.

You can find the preceding compilers at
`http://www.support.compaq.com/alpha-tools/'. By using these compilers
rather than `gcc', we get about 9-14% better MySQL performance.

For MySQL on Alpha, we use the `-arch generic' flag to our compile
options, which ensures that the binary runs on all Alpha processors. We
also compile statically to avoid library problems. The `configure'
command looks like this:

     CC=ccc CFLAGS="-fast -arch generic" CXX=cxx \
     CXXFLAGS="-fast -arch generic -noexceptions -nortti" \
     ./configure --prefix=/usr/local/mysql --disable-shared \
         --with-extra-charsets=complex --enable-thread-safe-client \
         --with-mysqld-ldflags=-non_shared --with-client-ldflags=-non_shared

Some known problems when running MySQL on Linux-Alpha:

   * Debugging threaded applications like MySQL does not work with `gdb
     4.18'. You should use `gdb' 5.1 instead.

   * If you try linking *Note `mysqld': mysqld. statically when using
     `gcc', the resulting image dumps core at startup time. In other
     words, _do not_ use `--with-mysqld-ldflags=-all-static' with `gcc'.


File: manual.info,  Node: linux-powerpc,  Next: linux-mips,  Prev: linux-alpha,  Up: linux

2.12.1.8 Linux PowerPC Notes
............................

MySQL should work on MkLinux with the newest `glibc' package (tested
with `glibc' 2.0.7).


File: manual.info,  Node: linux-mips,  Next: linux-ia-64,  Prev: linux-powerpc,  Up: linux

2.12.1.9 Linux MIPS Notes
.........................

To get MySQL to work on Qube2 (Linux Mips), you need the newest `glibc'
libraries.  `glibc-2.0.7-29C2' is known to work. You must also use
`gcc' 2.95.2 or newer).


File: manual.info,  Node: linux-ia-64,  Next: selinux,  Prev: linux-mips,  Up: linux

2.12.1.10 Linux IA-64 Notes
...........................

To get MySQL to compile on Linux IA-64, we use the following
`configure' command for building with `gcc' 2.96:

     CC=gcc \
     CFLAGS="-O3 -fno-omit-frame-pointer" \
     CXX=gcc \
     CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors \
         -fno-exceptions -fno-rtti" \
         ./configure --prefix=/usr/local/mysql \
         "--with-comment=Official MySQL binary" \
         --with-extra-charsets=complex

On IA-64, the MySQL client binaries use shared libraries. This means
that if you install our binary distribution at a location other than
`/usr/local/mysql', you need to add the path of the directory where you
have `libmysqlclient.so' installed either to the `/etc/ld.so.conf' file
or to the value of your `LD_LIBRARY_PATH' environment variable.

See *Note link-errors::.


File: manual.info,  Node: selinux,  Prev: linux-ia-64,  Up: linux

2.12.1.11 SELinux Notes
.......................

RHEL4 comes with SELinux, which supports tighter access control for
processes. If SELinux is enabled (`SELINUX' in `/etc/selinux/config' is
set to `enforcing', `SELINUXTYPE' is set to either `targeted' or
`strict'), you might encounter problems installing MySQL AB RPM
packages.

Red Hat has an update that solves this. It involves an update of the
`security policy' specification to handle the install structure of the
RPMs provided by MySQL AB. For further information, see
`https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=167551' and
`http://rhn.redhat.com/errata/RHBA-2006-0049.html'.

The preceding discussion applies only to RHEL4. The patch is
unnecessary for RHEL5.


File: manual.info,  Node: mac-os-x,  Next: solaris,  Prev: linux,  Up: operating-system-specific-notes

2.12.2 Mac OS X Notes
---------------------

* Menu:

* mac-os-x-10-x::                Mac OS X 10.x (Darwin)
* mac-os-x-server::              Mac OS X Server 1.2 (Rhapsody)

On Mac OS X, `tar' cannot handle long file names. If you need to unpack
a `.tar.gz' distribution, use `gnutar' instead.


File: manual.info,  Node: mac-os-x-10-x,  Next: mac-os-x-server,  Prev: mac-os-x,  Up: mac-os-x

2.12.2.1 Mac OS X 10.x (Darwin)
...............................

MySQL should work without major problems on Mac OS X 10.x (Darwin).

Known issues:

   * If you have problems with performance under heavy load, try using
     the `--skip-thread-priority' option to *Note `mysqld': mysqld.
     This runs all threads with the same priority. On Mac OS X, this
     gives better performance, at least until Apple fixes its thread
     scheduler.

   * The connection times (`wait_timeout', `interactive_timeout' and
     `net_read_timeout') values are not honored.

     This is probably a signal handling problem in the thread library
     where the signal doesn't break a pending read and we hope that a
     future update to the thread libraries will fix this.

Our binary for Mac OS X is compiled on Darwin 6.3 with the following
`configure' line:

     CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc \
     CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors \
         -fno-exceptions -fno-rtti" \
         ./configure --prefix=/usr/local/mysql \
         --with-extra-charsets=complex --enable-thread-safe-client \
         --enable-local-infile --disable-shared

See *Note mac-os-x-installation::.


File: manual.info,  Node: mac-os-x-server,  Prev: mac-os-x-10-x,  Up: mac-os-x

2.12.2.2 Mac OS X Server 1.2 (Rhapsody)
.......................................

For current versions of Mac OS X Server, no operating system changes
are necessary before compiling MySQL. Compiling for the Server platform
is the same as for the client version of Mac OS X.

For older versions (Mac OS X Server 1.2, a.k.a. Rhapsody), you must
first install a pthread package before trying to configure MySQL.

See *Note mac-os-x-installation::.


File: manual.info,  Node: solaris,  Next: bsd-notes,  Prev: mac-os-x,  Up: operating-system-specific-notes

2.12.3 Solaris Notes
--------------------

* Menu:

* solaris-2-7::                  Solaris 2.7/2.8 Notes
* solaris-x86::                  Solaris x86 Notes

For information about installing MySQL on Solaris using PKG
distributions, see *Note solaris-installation::.

On Solaris, you may run into trouble even before you get the MySQL
distribution unpacked, as the Solaris `tar' cannot handle long file
names. This means that you may see errors when you try to unpack MySQL.

If this occurs, you must use GNU `tar' (`gtar') to unpack the
distribution.

Sun native threads work only on Solaris 2.5 and higher. For Solaris 2.4
and earlier, MySQL automatically uses MIT-pthreads.  See *Note
mit-pthreads::.

If you get the following error from `configure', it means that you have
something wrong with your compiler installation:

     checking for restartable system calls... configure: error can not
     run test programs while cross compiling

In this case, you should upgrade your compiler to a newer version. You
may also be able to solve this problem by inserting the following row
into the `config.cache' file:

     ac_cv_sys_restartable_syscalls=${ac_cv_sys_restartable_syscalls='no'}

If you are using Solaris on a SPARC, the recommended compiler is `gcc'
2.95.2 or 3.2. You can find this at `http://gcc.gnu.org/'. Note that
`gcc' 2.8.1 does not work reliably on SPARC.

The recommended `configure' line when using `gcc' 2.95.2 is:

     CC=gcc CFLAGS="-O3" \
     CXX=gcc CXXFLAGS="-O3 -felide-constructors -fno-exceptions -fno-rtti" \
     ./configure --prefix=/usr/local/mysql --with-low-memory \
         --enable-assembler

If you have an UltraSPARC system, you can get 4% better performance by
adding `-mcpu=v8 -Wa,-xarch=v8plusa' to the `CFLAGS' and `CXXFLAGS'
environment variables.

If you have Sun's Forte 5.0 (or newer) compiler, you can run
`configure' like this:

     CC=cc CFLAGS="-Xa -fast -native -xstrconst -mt" \
     CXX=CC CXXFLAGS="-noex -mt" \
     ./configure --prefix=/usr/local/mysql --enable-assembler

To create a 64-bit binary with Sun's Forte compiler, use the following
configuration options:

     CC=cc CFLAGS="-Xa -fast -native -xstrconst -mt -xarch=v9" \
     CXX=CC CXXFLAGS="-noex -mt -xarch=v9" ASFLAGS="-xarch=v9" \
     ./configure --prefix=/usr/local/mysql --enable-assembler

To create a 64-bit Solaris binary using `gcc', add `-m64' to `CFLAGS'
and `CXXFLAGS' and remove `--enable-assembler' from the `configure'
line.

In the MySQL benchmarks, we obtained a 4% speed increase on UltraSPARC
when using Forte 5.0 in 32-bit mode, as compared to using `gcc' 3.2
with the `-mcpu' flag.

If you create a 64-bit *Note `mysqld': mysqld. binary, it is 4% slower
than the 32-bit binary, but can handle more threads and memory.

When using Solaris 10 for x86_64, you should mount any file systems on
which you intend to store `InnoDB' files with the `forcedirectio'
option. (By default mounting is done without this option.) Failing to
do so will cause a significant drop in performance when using the
`InnoDB' storage engine on this platform.

If you get a problem with `fdatasync' or `sched_yield', you can fix
this by adding `LIBS=-lrt' to the `configure' line

For compilers older than WorkShop 5.3, you might have to edit the
`configure' script. Change this line:

     #if !defined(__STDC__) || __STDC__ != 1

To this:

     #if !defined(__STDC__)

If you turn on `__STDC__' with the `-Xc' option, the Sun compiler can't
compile with the Solaris `pthread.h' header file. This is a Sun bug
(broken compiler or broken include file).

If *Note `mysqld': mysqld. issues the following error message when you
run it, you have tried to compile MySQL with the Sun compiler without
enabling the `-mt' multi-thread option:

     libc internal error: _rmutex_unlock: rmutex not held

Add `-mt' to `CFLAGS' and `CXXFLAGS' and recompile.

If you are using the SFW version of `gcc' (which comes with Solaris 8),
you must add `/opt/sfw/lib' to the environment variable
`LD_LIBRARY_PATH' before running `configure'.

If you are using the `gcc' available from `sunfreeware.com', you may
have many problems.  To avoid this, you should recompile `gcc' and GNU
`binutils' on the machine where you are running them.

If you get the following error when compiling MySQL with `gcc', it
means that your `gcc' is not configured for your version of Solaris:

     shell> gcc -O3 -g -O2 -DDBUG_OFF  -o thr_alarm ...
     ./thr_alarm.c: In function `signal_hand':
     ./thr_alarm.c:556: too many arguments to function `sigwait'

The proper thing to do in this case is to get the newest version of
`gcc' and compile it with your current `gcc' compiler. At least for
Solaris 2.5, almost all binary versions of `gcc' have old, unusable
include files that break all programs that use threads, and possibly
other programs as well.

Solaris does not provide static versions of all system libraries
(`libpthreads' and `libdl'), so you cannot compile MySQL with
`--static'. If you try to do so, you get one of the following errors:

     ld: fatal: library -ldl: not found
     undefined reference to `dlopen'
     cannot find -lrt

If you link your own MySQL client programs, you may see the following
error at runtime:

     ld.so.1: fatal: libmysqlclient.so.#:
     open failed: No such file or directory

This problem can be avoided by one of the following methods:

   * Link clients with the `-Wl,r/full/path/to/libmysqlclient.so' flag
     rather than with `-Lpath').

   * Copy `libmysqclient.so' to `/usr/lib'.

   * Add the path name of the directory where `libmysqlclient.so' is
     located to the `LD_RUN_PATH' environment variable before running
     your client.

If you have problems with `configure' trying to link with `-lz' when
you don't have `zlib' installed, you have two options:

   * If you want to be able to use the compressed communication
     protocol, you need to get and install `zlib' from `ftp.gnu.org'.

   * Run `configure' with the `--with-named-z-libs=no' option when
     building MySQL.

If you are using `gcc' and have problems with loading user-defined
functions (UDFs) into MySQL, try adding `-lgcc' to the link line for
the UDF.

If you would like MySQL to start automatically, you can copy
`support-files/mysql.server' to `/etc/init.d' and create a symbolic
link to it named `/etc/rc3.d/S99mysql.server'.

If too many processes try to connect very rapidly to *Note `mysqld':
mysqld, you should see this error in the MySQL log:

     Error in accept: Protocol error

You might try starting the server with the `--back_log=50' option as a
workaround for this. (Use `-O back_log=50' before MySQL 4.)

Solaris doesn't support core files for `setuid()' applications, so you
can't get a core file from *Note `mysqld': mysqld. if you are using the
`--user' option.


File: manual.info,  Node: solaris-2-7,  Next: solaris-x86,  Prev: solaris,  Up: solaris

2.12.3.1 Solaris 2.7/2.8 Notes
..............................

Normally, you can use a Solaris 2.6 binary on Solaris 2.7 and 2.8. Most
of the Solaris 2.6 issues also apply for Solaris 2.7 and 2.8.

MySQL should be able to detect new versions of Solaris automatically
and enable workarounds for the following problems.

Solaris 2.7 / 2.8 has some bugs in the include files. You may see the
following error when you use `gcc':

     /usr/include/widec.h:42: warning: `getwc' redefined
     /usr/include/wchar.h:326: warning: this is the location of the previous
     definition

If this occurs, you can fix the problem by copying
`/usr/include/widec.h' to `.../lib/gcc-lib/os/gcc-version/include' and
changing line 41 from this:

     #if     !defined(lint) && !defined(__lint)

To this:

     #if     !defined(lint) && !defined(__lint) && !defined(getwc)

Alternatively, you can edit `/usr/include/widec.h' directly. Either
way, after you make the fix, you should remove `config.cache' and run
`configure' again.

If you get the following errors when you run `make', it is because
`configure' didn't detect the `curses.h' file (probably because of the
error in `/usr/include/widec.h'):

     In file included from mysql.cc:50:
     /usr/include/term.h:1060: syntax error before `,'
     /usr/include/term.h:1081: syntax error before `;'

The solution to this problem is to do one of the following:

   * Configure with `CFLAGS=-DHAVE_CURSES_H CXXFLAGS=-DHAVE_CURSES_H
     ./configure'.

   * Edit `/usr/include/widec.h' as indicated in the preceding
     discussion and re-run `configure'.

   * Remove the `#define HAVE_TERM' line from the `config.h' file and
     run `make' again.

If your linker cannot find `-lz' when linking client programs, the
problem is probably that your `libz.so' file is installed in
`/usr/local/lib'. You can fix this problem by one of the following
methods:

   * Add `/usr/local/lib' to `LD_LIBRARY_PATH'.

   * Add a link to `libz.so' from `/lib'.

   * If you are using Solaris 8, you can install the optional `zlib'
     from your Solaris 8 CD distribution.

   * Run `configure' with the `--with-named-z-libs=no' option when
     building MySQL.


File: manual.info,  Node: solaris-x86,  Prev: solaris-2-7,  Up: solaris

2.12.3.2 Solaris x86 Notes
..........................

On Solaris 8 on x86, *Note `mysqld': mysqld. dumps core if you remove
the debug symbols using `strip'.

If you are using `gcc' on Solaris x86 and you experience problems with
core dumps under load, you should use the following `configure' command:

     CC=gcc CFLAGS="-O3 -fomit-frame-pointer -DHAVE_CURSES_H" \
     CXX=gcc \
     CXXFLAGS="-O3 -fomit-frame-pointer -felide-constructors \
         -fno-exceptions -fno-rtti -DHAVE_CURSES_H" \
     ./configure --prefix=/usr/local/mysql

This avoids problems with the `libstdc++' library and with C++
exceptions.

If this doesn't help, you should compile a debug version and run it
with a trace file or under `gdb'. See MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).


File: manual.info,  Node: bsd-notes,  Next: other-unix-notes,  Prev: solaris,  Up: operating-system-specific-notes

2.12.4 BSD Notes
----------------

* Menu:

* freebsd::                      FreeBSD Notes
* netbsd::                       NetBSD Notes
* openbsd::                      OpenBSD 2.5 Notes
* bsdi::                         BSD/OS Version 2.x Notes
* bsdi3::                        BSD/OS Version 3.x Notes
* bsdi4::                        BSD/OS Version 4.x Notes

This section provides information about using MySQL on variants of BSD
Unix.


File: manual.info,  Node: freebsd,  Next: netbsd,  Prev: bsd-notes,  Up: bsd-notes

2.12.4.1 FreeBSD Notes
......................

FreeBSD 4.x or newer is recommended for running MySQL, because the
thread package is much more integrated. To get a secure and stable
system, you should use only FreeBSD kernels that are marked `-RELEASE'.

The easiest (and preferred) way to install MySQL is to use the *Note
`mysql-server': mysql-server. and `mysql-client' ports available at
`http://www.freebsd.org/'. Using these ports gives you the following
benefits:

   * A working MySQL with all optimizations enabled that are known to
     work on your version of FreeBSD.

   * Automatic configuration and build.

   * Startup scripts installed in `/usr/local/etc/rc.d'.

   * The ability to use `pkg_info -L' to see which files are installed.

   * The ability to use `pkg_delete' to remove MySQL if you no longer
     want it on your machine.

It is recommended you use MIT-pthreads on FreeBSD 2.x, and native
threads on FreeBSD 3 and up. It is possible to run with native threads
on some late 2.2.x versions, but you may encounter problems shutting
down *Note `mysqld': mysqld.

Unfortunately, certain function calls on FreeBSD are not yet fully
thread-safe. Most notably, this includes the `gethostbyname()'
function, which is used by MySQL to convert host names into IP
addresses. Under certain circumstances, the *Note `mysqld': mysqld.
process suddenly causes 100% CPU load and is unresponsive. If you
encounter this problem, try to start MySQL using the
`--skip-name-resolve' option.

Alternatively, you can link MySQL on FreeBSD 4.x against the
LinuxThreads library, which avoids a few of the problems that the
native FreeBSD thread implementation has. For a very good comparison of
LinuxThreads versus native threads, see Jeremy Zawodny's article
`FreeBSD or Linux for your MySQL Server?' at
`http://jeremy.zawodny.com/blog/archives/000697.html'.

Known problem when using LinuxThreads on FreeBSD is:

   * The connection times (`wait_timeout', `interactive_timeout' and
     `net_read_timeout') values are not honored. The symptom is that
     persistent connections can hang for a very long time without
     getting closed down and that a 'kill' for a thread will not take
     affect until the thread does it a new command

     This is probably a signal handling problem in the thread library
     where the signal doesn't break a pending read.  This is supposed
     to be fixed in FreeBSD 5.0

The MySQL build process requires GNU make (`gmake') to work. If GNU
`make' is not available, you must install it first before compiling
MySQL.

The recommended way to compile and install MySQL on FreeBSD with `gcc'
(2.95.2 and up) is:

     CC=gcc CFLAGS="-O2 -fno-strength-reduce" \
         CXX=gcc CXXFLAGS="-O2 -fno-rtti -fno-exceptions \
         -felide-constructors -fno-strength-reduce" \
         ./configure --prefix=/usr/local/mysql --enable-assembler
     gmake
     gmake install
     cd /usr/local/mysql
     bin/mysql_install_db --user=mysql
     bin/mysqld_safe &

If you notice that `configure' uses MIT-pthreads, you should read the
MIT-pthreads notes. See *Note mit-pthreads::.

If you get an error from `make install' that it can't find
`/usr/include/pthreads', `configure' didn't detect that you need
MIT-pthreads. To fix this problem, remove `config.cache', and then
re-run `configure' with the `--with-mit-threads' option.

Be sure that your name resolver setup is correct. Otherwise, you may
experience resolver delays or failures when connecting to *Note
`mysqld': mysqld. Also make sure that the `localhost' entry in the
`/etc/hosts' file is correct. The file should start with a line similar
to this:

     127.0.0.1       localhost localhost.your.domain

FreeBSD is known to have a very low default file handle limit.  See
*Note not-enough-file-handles::. Start the server by using the
`--open-files-limit' option for *Note `mysqld_safe': mysqld-safe, or
raise the limits for the *Note `mysqld': mysqld. user in
`/etc/login.conf' and rebuild it with `cap_mkdb /etc/login.conf'. Also
be sure that you set the appropriate class for this user in the password
file if you are not using the default (use `chpass mysqld-user-name').
See *Note mysqld-safe::.

FreeBSD limits the size of a process to 512MB, even if you have much
more RAM available on the system. So you may get an error such as this:

     Out of memory (Needed 16391 bytes)

In current versions of FreeBSD (at least 4.x and greater), you may
increase this limit by adding the following entries to the
`/boot/loader.conf' file and rebooting the machine (these are not
settings that can be changed at run time with the `sysctl' command):

     kern.maxdsiz="1073741824" # 1GB
     kern.dfldsiz="1073741824" # 1GB
     kern.maxssiz="134217728" # 128MB

For older versions of FreeBSD, you must recompile your kernel to change
the maximum data segment size for a process. In this case, you should
look at the `MAXDSIZ' option in the `LINT' config file for more
information.

If you get problems with the current date in MySQL, setting the `TZ'
variable should help. See *Note environment-variables::.


File: manual.info,  Node: netbsd,  Next: openbsd,  Prev: freebsd,  Up: bsd-notes

2.12.4.2 NetBSD Notes
.....................

To compile on NetBSD, you need GNU `make'.  Otherwise, the build
process fails when `make' tries to run `lint' on C++ files.


File: manual.info,  Node: openbsd,  Next: bsdi,  Prev: netbsd,  Up: bsd-notes

2.12.4.3 OpenBSD 2.5 Notes
..........................

On OpenBSD 2.5, you can compile MySQL with native threads with the
following options:

     CFLAGS=-pthread CXXFLAGS=-pthread ./configure --with-mit-threads=no


File: manual.info,  Node: bsdi,  Next: bsdi3,  Prev: openbsd,  Up: bsd-notes

2.12.4.4 BSD/OS Version 2.x Notes
.................................

If you get the following error when compiling MySQL, your `ulimit'
value for virtual memory is too low:

     item_func.h: In method
     `Item_func_ge::Item_func_ge(const Item_func_ge &)':
     item_func.h:28: virtual memory exhausted
     make[2]: *** [item_func.o] Error 1

Try using `ulimit -v 80000' and run `make' again. If this doesn't work
and you are using `bash', try switching to `csh' or `sh'; some BSDI
users have reported problems with `bash' and `ulimit'.

If you are using `gcc', you may also use have to use the
`--with-low-memory' flag for `configure' to be able to compile
`sql_yacc.cc'.

If you get problems with the current date in MySQL, setting the `TZ'
variable should help. See *Note environment-variables::.


File: manual.info,  Node: bsdi3,  Next: bsdi4,  Prev: bsdi,  Up: bsd-notes

2.12.4.5 BSD/OS Version 3.x Notes
.................................

Upgrade to BSD/OS 3.1. If that is not possible, install BSDIpatch
M300-038.

Use the following command when configuring MySQL:

     env CXX=shlicc++ CC=shlicc2 \
     ./configure \
         --prefix=/usr/local/mysql \
         --localstatedir=/var/mysql \
         --without-perl \
         --with-unix-socket-path=/var/mysql/mysql.sock

The following is also known to work:

     env CC=gcc CXX=gcc CXXFLAGS=-O3 \
     ./configure \
         --prefix=/usr/local/mysql \
         --with-unix-socket-path=/var/mysql/mysql.sock

You can change the directory locations if you wish, or just use the
defaults by not specifying any locations.

If you have problems with performance under heavy load, try using the
`--skip-thread-priority' option to *Note `mysqld': mysqld. This runs
all threads with the same priority. On BSDI 3.1, this gives better
performance, at least until BSDI fixes its thread scheduler.

If you get the error `virtual memory exhausted' while compiling, you
should try using `ulimit -v 80000' and running `make' again. If this
doesn't work and you are using `bash', try switching to `csh' or `sh';
some BSDI users have reported problems with `bash' and `ulimit'.


File: manual.info,  Node: bsdi4,  Prev: bsdi3,  Up: bsd-notes

2.12.4.6 BSD/OS Version 4.x Notes
.................................

BSDI 4.x has some thread-related bugs. If you want to use MySQL on
this, you should install all thread-related patches.  At least M400-023
should be installed.

On some BSDI 4.x systems, you may get problems with shared libraries.
The symptom is that you can't execute any client programs, for example,
*Note `mysqladmin': mysqladmin. In this case, you need to reconfigure
not to use shared libraries with the `--disable-shared' option to
configure.

Some customers have had problems on BSDI 4.0.1 that the *Note `mysqld':
mysqld. binary after a while can't open tables. This occurs because
some library/system-related bug causes *Note `mysqld': mysqld. to
change current directory without having asked for that to happen.

The fix is to either upgrade MySQL to at least version 3.23.34 or,
after running `configure', remove the line `#define HAVE_REALPATH' from
`config.h' before running `make'.

Note that this means that you can't symbolically link a database
directories to another database directory or symbolic link a table to
another database on BSDI. (Making a symbolic link to another disk is
okay).


File: manual.info,  Node: other-unix-notes,  Prev: bsd-notes,  Up: operating-system-specific-notes

2.12.5 Other Unix Notes
-----------------------

* Menu:

* hp-ux-10-20::                  HP-UX Version 10.20 Notes
* hp-ux-11-x::                   HP-UX Version 11.x Notes
* ibm-aix::                      IBM-AIX notes
* sunos::                        SunOS 4 Notes
* alpha-dec-unix::               Alpha-DEC-UNIX Notes (Tru64)
* alpha-dec-osf1::               Alpha-DEC-OSF/1 Notes
* sgi-irix::                     SGI Irix Notes
* sco::                          SCO UNIX and OpenServer 5.0.x Notes
* sco-openserver::               SCO OpenServer 6.0.x Notes
* sco-unixware::                 SCO UnixWare 7.1.x and OpenUNIX 8.0.0 Notes


File: manual.info,  Node: hp-ux-10-20,  Next: hp-ux-11-x,  Prev: other-unix-notes,  Up: other-unix-notes

2.12.5.1 HP-UX Version 10.20 Notes
..................................

If you install MySQL using a binary tarball distribution on HP-UX, you
may run into trouble even before you get the MySQL distribution
unpacked, as the HP-UX `tar' cannot handle long file names. This means
that you may see errors when you try to unpack MySQL.

If this occurs, you must use GNU `tar' (`gtar') to unpack the
distribution.

There are a couple of small problems when compiling MySQL on HP-UX. We
recommend that you use `gcc' instead of the HP-UX native compiler,
because `gcc' produces better code.

We recommend using `gcc' 2.95 on HP-UX. Don't use high optimization
flags (such as `-O6') because they may not be safe on HP-UX.

The following `configure' line should work with `gcc' 2.95:

     CFLAGS="-I/opt/dce/include -fpic" \
     CXXFLAGS="-I/opt/dce/include -felide-constructors -fno-exceptions \
     -fno-rtti" \
     CXX=gcc \
     ./configure --with-pthread \
         --with-named-thread-libs='-ldce' \
         --prefix=/usr/local/mysql --disable-shared

The following `configure' line should work with `gcc' 3.1:

     CFLAGS="-DHPUX -I/opt/dce/include -O3 -fPIC" CXX=gcc \
     CXXFLAGS="-DHPUX -I/opt/dce/include -felide-constructors \
         -fno-exceptions -fno-rtti -O3 -fPIC" \
     ./configure --prefix=/usr/local/mysql \
         --with-extra-charsets=complex --enable-thread-safe-client \
         --enable-local-infile  --with-pthread \
         --with-named-thread-libs=-ldce --with-lib-ccflags=-fPIC
         --disable-shared


File: manual.info,  Node: hp-ux-11-x,  Next: ibm-aix,  Prev: hp-ux-10-20,  Up: other-unix-notes

2.12.5.2 HP-UX Version 11.x Notes
.................................

If you install MySQL using a binary tarball distribution on HP-UX, you
may run into trouble even before you get the MySQL distribution
unpacked, as the HP-UX `tar' cannot handle long file names. This means
that you may see errors when you try to unpack MySQL.

If this occurs, you must use GNU `tar' (`gtar') to unpack the
distribution.

Because of some critical bugs in the standard HP-UX libraries, you
should install the following patches before trying to run MySQL on
HP-UX 11.0:

     PHKL_22840 Streams cumulative
     PHNE_22397 ARPA cumulative

This solves the problem of getting `EWOULDBLOCK' from `recv()' and
`EBADF' from `accept()' in threaded applications.

If you are using `gcc' 2.95.1 on an unpatched HP-UX 11.x system, you
may get the following error:

     In file included from /usr/include/unistd.h:11,
                      from ../include/global.h:125,
                      from mysql_priv.h:15,
                      from item.cc:19:
     /usr/include/sys/unistd.h:184: declaration of C function ...
     /usr/include/sys/pthread.h:440: previous declaration ...
     In file included from item.h:306,
                      from mysql_priv.h:158,
                      from item.cc:19:

The problem is that HP-UX does not define `pthreads_atfork()'
consistently. It has conflicting prototypes in
`/usr/include/sys/unistd.h':184 and `/usr/include/sys/pthread.h':440.

One solution is to copy `/usr/include/sys/unistd.h' into
`mysql/include' and edit `unistd.h' and change it to match the
definition in `pthread.h'. Look for this line:

     extern int pthread_atfork(void (*prepare)(), void (*parent)(),
                                               void (*child)());

Change it to look like this:

     extern int pthread_atfork(void (*prepare)(void), void (*parent)(void),
                                               void (*child)(void));

After making the change, the following `configure' line should work:

     CFLAGS="-fomit-frame-pointer -O3 -fpic" CXX=gcc \
     CXXFLAGS="-felide-constructors -fno-exceptions -fno-rtti -O3" \
     ./configure --prefix=/usr/local/mysql --disable-shared

If you are using HP-UX compiler, you can use the following command
(which has been tested with `cc' B.11.11.04):

     CC=cc CXX=aCC CFLAGS=+DD64 CXXFLAGS=+DD64 ./configure \
         --with-extra-character-set=complex

You can ignore any errors of the following type:

     aCC: warning 901: unknown option: `-3': use +help for online
     documentation

If you get the following error from `configure', verify that you don't
have the path to the K&R compiler before the path to the HP-UX C and
C++ compiler:

     checking for cc option to accept ANSI C... no
     configure: error: MySQL requires an ANSI C compiler (and a C++ compiler).
     Try gcc. See the Installation chapter in the Reference Manual.

Another reason for not being able to compile is that you didn't define
the `+DD64' flags as just described.

Another possibility for HP-UX 11 is to use the MySQL binaries provided
at `http://dev.mysql.com/downloads/', which we have built and tested
ourselves. We have also received reports that the HP-UX 10.20 binaries
supplied by MySQL can be run successfully on HP-UX 11. If you encounter
problems, you should be sure to check your HP-UX patch level.


File: manual.info,  Node: ibm-aix,  Next: sunos,  Prev: hp-ux-11-x,  Up: other-unix-notes

2.12.5.3 IBM-AIX notes
......................

Automatic detection of `xlC' is missing from Autoconf, so a number of
variables need to be set before running `configure'. The following
example uses the IBM compiler:

     export CC="xlc_r -ma -O3 -qstrict -qoptimize=3 -qmaxmem=8192 "
     export CXX="xlC_r -ma -O3 -qstrict -qoptimize=3 -qmaxmem=8192"
     export CFLAGS="-I /usr/local/include"
     export LDFLAGS="-L /usr/local/lib"
     export CPPFLAGS=$CFLAGS
     export CXXFLAGS=$CFLAGS

     ./configure --prefix=/usr/local \
                     --localstatedir=/var/mysql \
                     --sbindir='/usr/local/bin' \
                     --libexecdir='/usr/local/bin' \
                     --enable-thread-safe-client \
                     --enable-large-files

The preceding options are used to compile the MySQL distribution that
can be found at `http://www-frec.bull.com/'.

If you change the `-O3' to `-O2' in the preceding `configure' line, you
must also remove the `-qstrict' option. This is a limitation in the IBM
C compiler.

If you are using `gcc' to compile MySQL, you _must_ use the
`-fno-exceptions' flag, because the exception handling in `gcc' is not
thread-safe! There are also some known problems with IBM's assembler
that may cause it to generate bad code when used with `gcc'.

We recommend the following `configure' line with `gcc' 2.95 on AIX:

     CC="gcc -pipe -mcpu=power -Wa,-many" \
     CXX="gcc -pipe -mcpu=power -Wa,-many" \
     CXXFLAGS="-felide-constructors -fno-exceptions -fno-rtti" \
     ./configure --prefix=/usr/local/mysql --with-low-memory

The `-Wa,-many' option is necessary for the compile to be successful.
IBM is aware of this problem but is in no hurry to fix it because of
the workaround that is available. We don't know if the
`-fno-exceptions' is required with `gcc' 2.95, but because MySQL
doesn't use exceptions and the option generates faster code, we
recommend that you should always use it with `gcc'.

If you get a problem with assembler code, try changing the `-mcpu=XXX'
option to match your CPU. Typically `power2', `power', or `powerpc' may
need to be used. Alternatively, you might need to use `604' or `604e'.
We are not positive but suspect that `power' would likely be safe most
of the time, even on a power2 machine.

If you don't know what your CPU is, execute a `uname -m' command. It
produces a string that looks like `000514676700', with a format of
`xxyyyyyymmss' where `xx' and `ss' are always `00', `yyyyyy' is a
unique system ID and `mm' is the ID of the CPU Planar. A chart of these
values can be found at
`http://www16.boulder.ibm.com/pseries/en_US/cmds/aixcmds5/uname.htm'.

This gives you a machine type and a machine model you can use to
determine what type of CPU you have.

If you have problems with signals (MySQL dies unexpectedly under high
load), you may have found an OS bug with threads and signals. In this
case, you can tell MySQL not to use signals by configuring as follows:

     CFLAGS=-DDONT_USE_THR_ALARM CXX=gcc \
     CXXFLAGS="-felide-constructors -fno-exceptions -fno-rtti \
     -DDONT_USE_THR_ALARM" \
     ./configure --prefix=/usr/local/mysql --with-debug \
         --with-low-memory

This doesn't affect the performance of MySQL, but has the side effect
that you can't kill clients that are `sleeping' on a connection with
*Note `mysqladmin kill': mysqladmin. or *Note `mysqladmin shutdown':
mysqladmin. Instead, the client dies when it issues its next command.

On some versions of AIX, linking with `libbind.a' makes
`getservbyname()' dump core. This is an AIX bug and should be reported
to IBM.

For AIX 4.2.1 and `gcc', you have to make the following changes.

After configuring, edit `config.h' and `include/my_config.h' and change
the line that says this:

     #define HAVE_SNPRINTF 1

to this:

     #undef HAVE_SNPRINTF

And finally, in `mysqld.cc', you need to add a prototype for
`initgroups()'.

     #ifdef _AIX41
     extern "C" int initgroups(const char *,int);
     #endif

For 32-bit binaries, if you need to allocate a lot of memory to the
*Note `mysqld': mysqld. process, it is not enough to just use `ulimit
-d unlimited'. You may also have to modify *Note `mysqld_safe':
mysqld-safe. to add a line something like this:

     export LDR_CNTRL='MAXDATA=0x80000000'

You can find more information about using a lot of memory at
`http://publib16.boulder.ibm.com/pseries/en_US/aixprggd/genprogc/lrg_prg_support.htm'.

Users of AIX 4.3 should use `gmake' instead of the `make' utility
included with AIX.

As of AIX 4.1, the C compiler has been unbundled from AIX as a separate
product. We recommend using `gcc' 3.3.2, which can be obtained here:
`ftp://ftp.software.ibm.com/aix/freeSoftware/aixtoolbox/RPMS/ppc/gcc/'

The steps for compiling MySQL on AIX with `gcc' 3.3.2 are similar to
those for using `gcc' 2.95 (in particular, the need to edit `config.h'
and `my_config.h' after running `configure'). However, before running
`configure', you should also patch the `curses.h' file as follows:

     /opt/freeware/lib/gcc-lib/powerpc-ibm-aix5.2.0.0/3.3.2/include/curses.h.ORIG
            Mon Dec 26 02:17:28 2005
     --- /opt/freeware/lib/gcc-lib/powerpc-ibm-aix5.2.0.0/3.3.2/include/curses.h
     Mon Dec 26 02:40:13 2005
     ***************
     *** 2023,2029 ****

       #endif /* _AIX32_CURSES */
     ! #if defined(__USE_FIXED_PROTOTYPES__) || defined(__cplusplus) || defined
     (__STRICT_ANSI__)
       extern int delwin (WINDOW *);
       extern int endwin (void);
       extern int getcurx (WINDOW *);
     --- 2023,2029 ----

       #endif /* _AIX32_CURSES */
     ! #if 0 && (defined(__USE_FIXED_PROTOTYPES__) || defined(__cplusplus)
     || defined
     (__STRICT_ANSI__))
       extern int delwin (WINDOW *);
       extern int endwin (void);
       extern int getcurx (WINDOW *);


File: manual.info,  Node: sunos,  Next: alpha-dec-unix,  Prev: ibm-aix,  Up: other-unix-notes

2.12.5.4 SunOS 4 Notes
......................

On SunOS 4, MIT-pthreads is needed to compile MySQL. This in turn means
you need GNU `make'.

Some SunOS 4 systems have problems with dynamic libraries and
`libtool'. You can use the following `configure' line to avoid this
problem:

     ./configure --disable-shared --with-mysqld-ldflags=-all-static

When compiling `readline', you may get warnings about duplicate
defines. These can be ignored.

When compiling *Note `mysqld': mysqld, there are some `implicit
declaration of function' warnings.  These can be ignored.


File: manual.info,  Node: alpha-dec-unix,  Next: alpha-dec-osf1,  Prev: sunos,  Up: other-unix-notes

2.12.5.5 Alpha-DEC-UNIX Notes (Tru64)
.....................................

If you are using `egcs' 1.1.2 on Digital Unix, you should upgrade to
`gcc' 2.95.2, because `egcs' on DEC has some serious bugs!

When compiling threaded programs under Digital Unix, the documentation
recommends using the `-pthread' option for `cc' and `cxx' and the
`-lmach -lexc' libraries (in addition to `-lpthread'). You should run
`configure' something like this:

     CC="cc -pthread" CXX="cxx -pthread -O" \
     ./configure --with-named-thread-libs="-lpthread -lmach -lexc -lc"

When compiling *Note `mysqld': mysqld, you may see a couple of warnings
like this:

     mysqld.cc: In function void handle_connections()':
     mysqld.cc:626: passing long unsigned int *' as argument 3 of
     accept(int,sockadddr *, int *)'

You can safely ignore these warnings. They occur because `configure'
can detect only errors, not warnings.

If you start the server directly from the command line, you may have
problems with it dying when you log out. (When you log out, your
outstanding processes receive a `SIGHUP' signal.) If so, try starting
the server like this:

     nohup mysqld [OPTIONS] &

`nohup' causes the command following it to ignore any `SIGHUP' signal
sent from the terminal. Alternatively, start the server by running
*Note `mysqld_safe': mysqld-safe, which invokes *Note `mysqld': mysqld.
using `nohup' for you. See *Note mysqld-safe::.

If you get a problem when compiling `mysys/get_opt.c', just remove the
`#define _NO_PROTO' line from the start of that file.

If you are using Compaq's CC compiler, the following `configure' line
should work:

     CC="cc -pthread"
     CFLAGS="-O4 -ansi_alias -ansi_args -fast -inline speed \
             -speculate all -arch host"
     CXX="cxx -pthread"
     CXXFLAGS="-O4 -ansi_alias -ansi_args -fast -inline speed \
               -speculate all -arch host -noexceptions -nortti"
     export CC CFLAGS CXX CXXFLAGS
     ./configure \
         --prefix=/usr/local/mysql \
         --with-low-memory \
         --enable-large-files \
         --enable-shared=yes \
         --with-named-thread-libs="-lpthread -lmach -lexc -lc"
     gnumake

If you get a problem with `libtool' when compiling with shared
libraries as just shown, when linking *Note `mysql': mysql, you should
be able to get around this by issuing these commands:

     cd mysql
     /bin/sh ../libtool --mode=link cxx -pthread  -O3 -DDBUG_OFF \
         -O4 -ansi_alias -ansi_args -fast -inline speed \
         -speculate all \ -arch host  -DUNDEF_HAVE_GETHOSTBYNAME_R \
         -o mysql  mysql.o readline.o sql_string.o completion_hash.o \
         ../readline/libreadline.a -lcurses \
         ../libmysql/.libs/libmysqlclient.so  -lm
     cd ..
     gnumake
     gnumake install
     scripts/mysql_install_db


File: manual.info,  Node: alpha-dec-osf1,  Next: sgi-irix,  Prev: alpha-dec-unix,  Up: other-unix-notes

2.12.5.6 Alpha-DEC-OSF/1 Notes
..............................

If you have problems compiling and have DEC `CC' and `gcc' installed,
try running `configure' like this:

     CC=cc CFLAGS=-O CXX=gcc CXXFLAGS=-O3 \
     ./configure --prefix=/usr/local/mysql

If you get problems with the `c_asm.h' file, you can create and use a
'dummy' `c_asm.h' file with:

     touch include/c_asm.h
     CC=gcc CFLAGS=-I./include \
     CXX=gcc CXXFLAGS=-O3 \
     ./configure --prefix=/usr/local/mysql

Note that the following problems with the `ld' program can be fixed by
downloading the latest DEC (Compaq) patch kit from:
`http://ftp.support.compaq.com/public/unix/'.

On OSF/1 V4.0D and compiler "DEC C V5.6-071 on Digital Unix V4.0 (Rev.
878)," the compiler had some strange behavior (undefined `asm' symbols).
`/bin/ld' also appears to be broken (problems with `_exit undefined'
errors occurring while linking *Note `mysqld': mysqld.). On this
system, we have managed to compile MySQL with the following `configure'
line, after replacing `/bin/ld' with the version from OSF 4.0C:

     CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql

With the Digital compiler "C++ V6.1-029," the following should work:

     CC=cc -pthread
     CFLAGS=-O4 -ansi_alias -ansi_args -fast -inline speed \
            -speculate all -arch host
     CXX=cxx -pthread
     CXXFLAGS=-O4 -ansi_alias -ansi_args -fast -inline speed \
              -speculate all -arch host -noexceptions -nortti
     export CC CFLAGS CXX CXXFLAGS
     ./configure --prefix=/usr/mysql/mysql \
                 --with-mysqld-ldflags=-all-static --disable-shared \
                 --with-named-thread-libs="-lmach -lexc -lc"

In some versions of OSF/1, the `alloca()' function is broken. Fix this
by removing the line in `config.h' that defines `'HAVE_ALLOCA''.

The `alloca()' function also may have an incorrect prototype in
`/usr/include/alloca.h'. This warning resulting from this can be
ignored.

`configure' uses the following thread libraries automatically:
`--with-named-thread-libs="-lpthread -lmach -lexc -lc"'.

When using `gcc', you can also try running `configure' like this:

     CFLAGS=-D_PTHREAD_USE_D4 CXX=gcc CXXFLAGS=-O3 ./configure ...

If you have problems with signals (MySQL dies unexpectedly under high
load), you may have found an OS bug with threads and signals. In this
case, you can tell MySQL not to use signals by configuring with:

     CFLAGS=-DDONT_USE_THR_ALARM \
     CXXFLAGS=-DDONT_USE_THR_ALARM \
     ./configure ...

This does not affect the performance of MySQL, but has the side effect
that you can't kill clients that are `sleeping' on a connection with
*Note `mysqladmin kill': mysqladmin. or *Note `mysqladmin shutdown':
mysqladmin. Instead, the client dies when it issues its next command.

With `gcc' 2.95.2, you may encounter the following compile error:

     sql_acl.cc:1456: Internal compiler error in `scan_region',
     at except.c:2566
     Please submit a full bug report.

To fix this, you should change to the `sql' directory and do a
cut-and-paste of the last `gcc' line, but change `-O3' to `-O0' (or add
`-O0' immediately after `gcc' if you don't have any `-O' option on your
compile line). After this is done, you can just change back to the
top-level directory and run `make' again.


File: manual.info,  Node: sgi-irix,  Next: sco,  Prev: alpha-dec-osf1,  Up: other-unix-notes

2.12.5.7 SGI Irix Notes
.......................

As of MySQL 5.0, we don't provide binaries for Irix any more.

If you are using Irix 6.5.3 or newer, *Note `mysqld': mysqld. is able
to create threads only if you run it as a user that has `CAP_SCHED_MGT'
privileges (such as `root') or give the *Note `mysqld': mysqld. server
this privilege with the following shell command:

     chcap "CAP_SCHED_MGT+epi" /opt/mysql/libexec/mysqld

You may have to undefine some symbols in `config.h' after running
`configure' and before compiling.

In some Irix implementations, the `alloca()' function is broken. If the
*Note `mysqld': mysqld. server dies on some *Note `SELECT': select.
statements, remove the lines from `config.h' that define `HAVE_ALLOC'
and `HAVE_ALLOCA_H'. If *Note `mysqladmin create': mysqladmin. doesn't
work, remove the line from `config.h' that defines `HAVE_READDIR_R'.
You may have to remove the `HAVE_TERM_H' line as well.

SGI recommends that you install all the patches on this page as a set:
`http://support.sgi.com/surfzone/patches/patchset/6.2_indigo.rps.html'

At the very minimum, you should install the latest kernel rollup, the
latest `rld' rollup, and the latest `libc' rollup.

You definitely need all the POSIX patches on this page, for pthreads
support:

`http://support.sgi.com/surfzone/patches/patchset/6.2_posix.rps.html'

If you get the something like the following error when compiling
`mysql.cc':

     "/usr/include/curses.h", line 82: error(1084):
     invalid combination of type

Type the following in the top-level directory of your MySQL source tree:

     extra/replace bool curses_bool < /usr/include/curses.h > include/curses.h
     make

There have also been reports of scheduling problems. If only one thread
is running, performance is slow. Avoid this by starting another client.
This may lead to a two-to-tenfold increase in execution speed
thereafter for the other thread.  This is a poorly understood problem
with Irix threads; you may have to improvise to find solutions until
this can be fixed.

If you are compiling with `gcc', you can use the following `configure'
command:

     CC=gcc CXX=gcc CXXFLAGS=-O3 \
     ./configure --prefix=/usr/local/mysql --enable-thread-safe-client \
         --with-named-thread-libs=-lpthread

On Irix 6.5.11 with native Irix C and C++ compilers ver.  7.3.1.2, the
following is reported to work

     CC=cc CXX=CC CFLAGS='-O3 -n32 -TARG:platform=IP22 -I/usr/local/include \
     -L/usr/local/lib' CXXFLAGS='-O3 -n32 -TARG:platform=IP22 \
     -I/usr/local/include -L/usr/local/lib' \
     ./configure --prefix=/usr/local/mysql --with-innodb \
         --with-libwrap=/usr/local \
         --with-named-curses-libs=/usr/local/lib/libncurses.a


File: manual.info,  Node: sco,  Next: sco-openserver,  Prev: sgi-irix,  Up: other-unix-notes

2.12.5.8 SCO UNIX and OpenServer 5.0.x Notes
............................................

The current port is tested only on `sco3.2v5.0.5', `sco3.2v5.0.6', and
`sco3.2v5.0.7' systems. There has also been progress on a port to
`sco3.2v4.2'. Open Server 5.0.8 (Legend) has native threads and allows
files greater than 2GB. The current maximum file size is 2GB.

We have been able to compile MySQL with the following `configure'
command on OpenServer with `gcc' 2.95.3.

     CC=gcc CFLAGS="-D_FILE_OFFSET_BITS=64 -O3" \
     CXX=gcc CXXFLAGS="-D_FILE_OFFSET_BITS=64 -O3" \
     ./configure --prefix=/usr/local/mysql \
         --enable-thread-safe-client --with-innodb \
         --with-openssl --with-vio --with-extra-charsets=complex

`gcc' is available at
`ftp://ftp.sco.com/pub/openserver5/opensrc/gnutools-5.0.7Kj'.

This development system requires the OpenServer Execution Environment
Supplement oss646B on OpenServer 5.0.6 and oss656B and The OpenSource
libraries found in gwxlibs. All OpenSource tools are in the `opensrc'
directory. They are available at
`ftp://ftp.sco.com/pub/openserver5/opensrc/'.

We recommend using the latest production release of MySQL.

SCO provides operating system patches at
`ftp://ftp.sco.com/pub/openserver5' for OpenServer 5.0.[0-6] and
`ftp://ftp.sco.com/pub/openserverv5/507' for OpenServer 5.0.7.

SCO provides information about security fixes at
`ftp://ftp.sco.com/pub/security/OpenServer' for OpenServer 5.0.x.

The maximum file size on an OpenServer 5.0.x system is 2GB.

The total memory which can be allocated for streams buffers, clists,
and lock records cannot exceed 60MB on OpenServer 5.0.x.

Streams buffers are allocated in units of 4096 byte pages, clists are
70 bytes each, and lock records are 64 bytes each, so:

     (NSTRPAGES x 4096) + (NCLIST x 70) + (MAX_FLCKREC x 64) <= 62914560

Follow this procedure to configure the Database Services option. If you
are unsure whether an application requires this, see the documentation
provided with the application.

  1. Log in as `root'.

  2. Enable the SUDS driver by editing the `/etc/conf/sdevice.d/suds'
     file. Change the `N' in the second field to a `Y'.

  3. Use `mkdev aio' or the Hardware/Kernel Manager to enable support
     for asynchronous I/O and relink the kernel. To allow users to lock
     down memory for use with this type of I/O, update the
     aiomemlock(F) file. This file should be updated to include the
     names of users that can use AIO and the maximum amounts of memory
     they can lock down.

  4. Many applications use setuid binaries so that you need to specify
     only a single user. See the documentation provided with the
     application to determine whether this is the case for your
     application.

After you complete this process, reboot the system to create a new
kernel incorporating these changes.

By default, the entries in `/etc/conf/cf.d/mtune' are set as follows:

     Value           Default         Min             Max
     -----           -------         ---             ---
     NBUF            0               24              450000
     NHBUF           0               32              524288
     NMPBUF          0               12              512
     MAX_INODE       0               100             64000
     MAX_FILE        0               100             64000
     CTBUFSIZE       128             0               256
     MAX_PROC        0               50              16000
     MAX_REGION      0               500             160000
     NCLIST          170             120             16640
     MAXUP           100             15              16000
     NOFILES         110             60              11000
     NHINODE         128             64              8192
     NAUTOUP         10              0               60
     NGROUPS         8               0               128
     BDFLUSHR        30              1               300
     MAX_FLCKREC     0               50              16000
     PUTBUFSZ        8000            2000            20000
     MAXSLICE        100             25              100
     ULIMIT          4194303         2048            4194303
     * Streams Parameters
     NSTREAM         64              1               32768
     NSTRPUSH        9               9               9
     NMUXLINK        192             1               4096
     STRMSGSZ        16384           4096            524288
     STRCTLSZ        1024            1024            1024
     STRMAXBLK       524288          4096            524288
     NSTRPAGES       500             0               8000
     STRSPLITFRAC    80              50              100
     NLOG            3               3               3
     NUMSP           64              1               256
     NUMTIM          16              1               8192
     NUMTRW          16              1               8192
     * Semaphore Parameters
     SEMMAP          10              10              8192
     SEMMNI          10              10              8192
     SEMMNS          60              60              8192
     SEMMNU          30              10              8192
     SEMMSL          25              25              150
     SEMOPM          10              10              1024
     SEMUME          10              10              25
     SEMVMX          32767           32767           32767
     SEMAEM          16384           16384           16384
     * Shared Memory Parameters
     SHMMAX          524288          131072          2147483647
     SHMMIN          1               1               1
     SHMMNI          100             100             2000
     FILE            0               100             64000
     NMOUNT          0               4               256
     NPROC           0               50              16000
     NREGION         0               500             160000

We recommend setting these values as follows:

   * `NOFILES' should be 4096 or 2048.

   * `MAXUP' should be 2048.

To make changes to the kernel, use the `idtune NAME PARAMETER' command.
`idtune' modifies the `/etc/conf/cf.d/stune' file for you. For example,
to change `SEMMS' to `200', execute this command as `root':

     # /etc/conf/bin/idtune SEMMNS 200

Then rebuild and reboot the kernel by issuing this command:

     # /etc/conf/bin/idbuild -B && init 6

We recommend tuning the system, but the proper parameter values to use
depend on the number of users accessing the application or database and
size the of the database (that is, the used buffer pool). The following
kernel parameters can be set with `idtune':

   * `SHMMAX' (recommended setting: 128MB) and `SHMSEG' (recommended
     setting: 15). These parameters have an influence on the MySQL
     database engine to create user buffer pools.

   * `NOFILES' and `MAXUP' should be set to at least 2048.

   * `MAXPROC' should be set to at least 3000/4000 (depends on number
     of users) or more.

   * We also recommend using the following formulas to calculate values
     for `SEMMSL', `SEMMNS', and `SEMMNU':

          SEMMSL = 13

     13 is what has been found to be the best for both Progress and
     MySQL.

          SEMMNS = SEMMSL x NUMBER OF DB SERVERS TO BE RUN ON THE SYSTEM

     Set `SEMMNS' to the value of `SEMMSL' multiplied by the number of
     database servers (maximum) that you are running on the system at
     one time.

          SEMMNU = SEMMNS

     Set the value of `SEMMNU' to equal the value of `SEMMNS'. You
     could probably set this to 75% of `SEMMNS', but this is a
     conservative estimate.

You need to at least install the SCO OpenServer Linker and Application
Development Libraries or the OpenServer Development System to use
`gcc'. You cannot use the GCC Dev system without installing one of
these.

You should get the FSU Pthreads package and install it first.  This can
be found at
`http://moss.csc.ncsu.edu/~mueller/ftp/pub/PART/pthreads.tar.gz'.  You
can also get a precompiled package from
`ftp://ftp.zenez.com/pub/zenez/prgms/FSU-threads-3.14.tar.gz'.

FSU Pthreads can be compiled with SCO Unix 4.2 with tcpip, or using
OpenServer 3.0 or Open Desktop 3.0 (OS 3.0 ODT 3.0) with the SCO
Development System installed using a good port of GCC 2.5.x. For ODT or
OS 3.0, you need a good port of GCC 2.5.x.  There are a lot of problems
without a good port. The port for this product requires the SCO Unix
Development system. Without it, you are missing the libraries and the
linker that is needed. You also need `SCO-3.2v4.2-includes.tar.gz'.
This file contains the changes to the SCO Development include files that
are needed to get MySQL to build. You need to replace the existing
system include files with these modified header files. They can be
obtained from
`ftp://ftp.zenez.com/pub/zenez/prgms/SCO-3.2v4.2-includes.tar.gz'.

To build FSU Pthreads on your system, all you should need to do is run
GNU `make'. The `Makefile' in FSU-threads-3.14.tar.gz is set up to make
FSU-threads.

You can run `./configure' in the `threads/src' directory and select the
SCO OpenServer option. This command copies `Makefile.SCO5' to
`Makefile'. Then run `make'.

To install in the default `/usr/include' directory, log in as `root',
and then `cd' to the `thread/src' directory and run `make install'.

Remember that you must use GNU `make' to build MySQL.

*Note*:

If you don't start *Note `mysqld_safe': mysqld-safe. as `root', you
should get only the default 110 open files per process. *Note `mysqld':
mysqld. writes a note about this in the log file.

With SCO 3.2V4.2, you should use FSU Pthreads version 3.14 or newer.
The following `configure' command should work:

     CFLAGS="-D_XOPEN_XPG4" CXX=gcc CXXFLAGS="-D_XOPEN_XPG4" \
     ./configure \
         --prefix=/usr/local/mysql \
         --with-named-thread-libs="-lgthreads -lsocket -lgen -lgthreads" \
         --with-named-curses-libs="-lcurses"

You may have problems with some include files. In this case, you can
find new SCO-specific include files at
`ftp://ftp.zenez.com/pub/zenez/prgms/SCO-3.2v4.2-includes.tar.gz'.

You should unpack this file in the `include' directory of your MySQL
source tree.

SCO development notes:

   * MySQL should automatically detect FSU Pthreads and link *Note
     `mysqld': mysqld. with `-lgthreads -lsocket -lgthreads'.

   * The SCO development libraries are re-entrant in FSU Pthreads. SCO
     claims that its library functions are re-entrant, so they must be
     re-entrant with FSU Pthreads.  FSU Pthreads on OpenServer tries to
     use the SCO scheme to make re-entrant libraries.

   * FSU Pthreads (at least the version at `ftp://ftp.zenez.com') comes
     linked with GNU `malloc'. If you encounter problems with memory
     usage, make sure that `gmalloc.o' is included in `libgthreads.a'
     and `libgthreads.so'.

   * In FSU Pthreads, the following system calls are pthreads-aware:
     `read()', `write()', `getmsg()', `connect()', `accept(),'
     `select()', and `wait()'.

   * The CSSA-2001-SCO.35.2 (the patch is listed in custom as
     erg711905-dscr_remap security patch (version 2.0.0)) breaks FSU
     threads and makes *Note `mysqld': mysqld.  unstable. You have to
     remove this one if you want to run *Note `mysqld': mysqld. on an
     OpenServer 5.0.6 machine.

   * If you use SCO OpenServer 5, you may need to recompile FSU
     pthreads with `-DDRAFT7' in `CFLAGS'. Otherwise, `InnoDB' may hang
     at a *Note `mysqld': mysqld. startup.

   * SCO provides operating system patches at
     `ftp://ftp.sco.com/pub/openserver5' for OpenServer 5.0.x.

   * SCO provides security fixes and `libsocket.so.2' at
     `ftp://ftp.sco.com/pub/security/OpenServer' and
     `ftp://ftp.sco.com/pub/security/sse' for OpenServer 5.0.x.

   * Pre-OSR506 security fixes. Also, the `telnetd' fix at
     `ftp://stage.caldera.com/pub/security/openserver/' or
     `ftp://stage.caldera.com/pub/security/openserver/CSSA-2001-SCO.10/'
     as both `libsocket.so.2' and `libresolv.so.1' with instructions for
     installing on pre-OSR506 systems.

     It is probably a good idea to install these patches before trying
     to compile/use MySQL.

Beginning with Legend/OpenServer 6.0.0, there are native threads and no
2GB file size limit.


File: manual.info,  Node: sco-openserver,  Next: sco-unixware,  Prev: sco,  Up: other-unix-notes

2.12.5.9 SCO OpenServer 6.0.x Notes
...................................

OpenServer 6 includes these key improvements:

   * Larger file support up to 1 TB

   * Multiprocessor support increased from 4 to 32 processors

   * Increased memory support up to 64GB

   * Extending the power of UnixWare into OpenServer 6

   * Dramatic performance improvement

OpenServer 6.0.0 commands are organized as follows:

   * `/bin' is for commands that behave exactly the same as on
     OpenServer 5.0.x.

   * `/u95/bin' is for commands that have better standards conformance,
     for example Large File System (LFS) support.

   * `/udk/bin' is for commands that behave the same as on UnixWare
     7.1.4. The default is for the LFS support.

The following is a guide to setting `PATH' on OpenServer 6. If the user
wants the traditional OpenServer 5.0.x then `PATH' should be `/bin'
first. If the user wants LFS support, the path should be
`/u95/bin:/bin'. If the user wants UnixWare 7 support first, the path
would be `/udk/bin:/u95/bin:/bin:'.

We recommend using the latest production release of MySQL.  Should you
choose to use an older release of MySQL on OpenServer 6.0.x, you must
use a version of MySQL at least as recent as 3.22.13 to get fixes for
some portability and OS problems.

MySQL distribution files with names of the following form are `tar'
archives of media are tar archives of media images suitable for
installation with the SCO Software Manager (`/etc/custom') on SCO
OpenServer 6:

     mysql-PRODUCT-6.0.12-sco-osr6-i686.VOLS.tar

A distribution where PRODUCT is `pro-cert' is the Commercially licensed
MySQL Pro Certified server. A distribution where PRODUCT is
`pro-gpl-cert' is the MySQL Pro Certified server licensed under the
terms of the General Public License (GPL).

Select whichever distribution you wish to install and, after download,
extract the `tar' archive into an empty directory. For example:

     shell> mkdir /tmp/mysql-pro
     shell> cd /tmp/mysql-pro
     shell> tar xf /tmp/mysql-pro-cert-6.0.12-sco-osr6-i686.VOLS.tar

Prior to installation, back up your data in accordance with the
procedures outlined in *Note upgrade::.

Remove any previously installed `pkgadd' version of MySQL:

     shell> pkginfo mysql 2>&1 > /dev/null && pkgrm mysql

Install MySQL Pro from media images using the SCO Software Manager:

     shell> /etc/custom -p SCO:MySQL -i -z /tmp/mysql-pro

Alternatively, the SCO Software Manager can be displayed graphically by
clicking on the `Software Manager' icon on the desktop, selecting
`Software -> Install New', selecting the host, selecting `Media Images'
for the Media Device, and entering `/tmp/mysql-pro' as the Image
Directory.

After installation, run `mkdev mysql' as the `root' user to configure
your newly installed MySQL Pro Certified server.

*Note*:

The installation procedure for VOLS packages does not create the
`mysql' user and group that the package uses by default. You should
either create the `mysql' user and group, or else select a different
user and group using an option in `mkdev mysql'.

If you wish to configure your MySQL Pro server to interface with the
Apache Web server via PHP, download and install the PHP update from SCO
at `ftp://ftp.sco.com/pub/updates/OpenServer/SCOSA-2006.17/'.

We have been able to compile MySQL with the following `configure'
command on OpenServer 6.0.x:

     CC=cc CFLAGS="-D_FILE_OFFSET_BITS=64 -O3" \
     CXX=CC CXXFLAGS="-D_FILE_OFFSET_BITS=64 -O3" \
     ./configure --prefix=/usr/local/mysql \
         --enable-thread-safe-client  \
         --with-extra-charsets=complex \
         --build=i686-unknown-sysv5SCO_SV6.0.0

If you use `gcc', you must use `gcc' 2.95.3 or newer.

     CC=gcc CXX=g++ ... ./configure ...

SCO provides OpenServer 6 operating system patches at
`ftp://ftp.sco.com/pub/openserver6'.

SCO provides information about security fixes at
`ftp://ftp.sco.com/pub/security/OpenServer'.

By default, the maximum file size on a OpenServer 6.0.0 system is 1TB.
Some operating system utilities have a limitation of 2GB. The maximum
possible file size on UnixWare 7 is 1TB with VXFS or HTFS.

OpenServer 6 can be configured for large file support (file sizes
greater than 2GB) by tuning the UNIX kernel.

By default, the entries in `/etc/conf/cf.d/mtune' are set as follows:

     Value           Default         Min             Max
     -----           -------         ---             ---
     SVMMLIM         0x9000000       0x1000000       0x7FFFFFFF
     HVMMLIM         0x9000000       0x1000000       0x7FFFFFFF

To make changes to the kernel, use the `idtune NAME PARAMETER' command.
`idtune' modifies the `/etc/conf/cf.d/stune' file for you. We recommend
setting the kernel values by executing the following commands as `root':

     # /etc/conf/bin/idtune SDATLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune HDATLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune SVMMLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune HVMMLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune SFNOLIM 2048
     # /etc/conf/bin/idtune HFNOLIM 2048

Then rebuild and reboot the kernel by issuing this command:

     # /etc/conf/bin/idbuild -B && init 6

We recommend tuning the system, but the proper parameter values to use
depend on the number of users accessing the application or database and
size the of the database (that is, the used buffer pool). The following
kernel parameters can be set with `idtune':

   * `SHMMAX' (recommended setting: 128MB) and `SHMSEG' (recommended
     setting: 15). These parameters have an influence on the MySQL
     database engine to create user buffer pools.

   * `SFNOLIM' and `HFNOLIM' should be at maximum 2048.

   * `NPROC' should be set to at least 3000/4000 (depends on number of
     users).

   * We also recommend using the following formulas to calculate values
     for `SEMMSL', `SEMMNS', and `SEMMNU':

          SEMMSL = 13

     13 is what has been found to be the best for both Progress and
     MySQL.

          SEMMNS = SEMMSL x NUMBER OF DB SERVERS TO BE RUN ON THE SYSTEM

     Set `SEMMNS' to the value of `SEMMSL' multiplied by the number of
     database servers (maximum) that you are running on the system at
     one time.

          SEMMNU = SEMMNS

     Set the value of `SEMMNU' to equal the value of `SEMMNS'. You
     could probably set this to 75% of `SEMMNS', but this is a
     conservative estimate.


File: manual.info,  Node: sco-unixware,  Prev: sco-openserver,  Up: other-unix-notes

2.12.5.10 SCO UnixWare 7.1.x and OpenUNIX 8.0.0 Notes
.....................................................

We recommend using the latest production release of MySQL.  Should you
choose to use an older release of MySQL on UnixWare 7.1.x, you must use
a version of MySQL at least as recent as 3.22.13 to get fixes for some
portability and OS problems.

We have been able to compile MySQL with the following `configure'
command on UnixWare 7.1.x:

     CC="cc" CFLAGS="-I/usr/local/include" \
     CXX="CC" CXXFLAGS="-I/usr/local/include" \
     ./configure --prefix=/usr/local/mysql \
         --enable-thread-safe-client \
         --with-innodb --with-openssl --with-extra-charsets=complex

If you want to use `gcc', you must use `gcc' 2.95.3 or newer.

     CC=gcc CXX=g++ ... ./configure ...

SCO provides operating system patches at
`ftp://ftp.sco.com/pub/unixware7' for UnixWare 7.1.1,
`ftp://ftp.sco.com/pub/unixware7/713/' for UnixWare 7.1.3,
`ftp://ftp.sco.com/pub/unixware7/714/' for UnixWare 7.1.4, and
`ftp://ftp.sco.com/pub/openunix8' for OpenUNIX 8.0.0.

SCO provides information about security fixes at
`ftp://ftp.sco.com/pub/security/OpenUNIX' for OpenUNIX and
`ftp://ftp.sco.com/pub/security/UnixWare' for UnixWare.

The UnixWare 7 file size limit is 1 TB with VXFS. Some OS utilities
have a limitation of 2GB.

On UnixWare 7.1.4 you do not need to do anything to get large file
support, but to enable large file support on prior versions of UnixWare
7.1.x, run `fsadm'.

     # fsadm -Fvxfs -o largefiles /
     # fsadm /         * Note
     # ulimit unlimited
     # /etc/conf/bin/idtune SFSZLIM 0x7FFFFFFF     ** Note
     # /etc/conf/bin/idtune HFSZLIM 0x7FFFFFFF     ** Note
     # /etc/conf/bin/idbuild -B

     * This should report "largefiles".
     ** 0x7FFFFFFF represents infinity for these values.

Reboot the system using `shutdown'.

By default, the entries in `/etc/conf/cf.d/mtune' are set as follows:

     Value           Default         Min             Max
     -----           -------         ---             ---
     SVMMLIM         0x9000000       0x1000000       0x7FFFFFFF
     HVMMLIM         0x9000000       0x1000000       0x7FFFFFFF

To make changes to the kernel, use the `idtune NAME PARAMETER' command.
`idtune' modifies the `/etc/conf/cf.d/stune' file for you. We recommend
setting the kernel values by executing the following commands as `root':

     # /etc/conf/bin/idtune SDATLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune HDATLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune SVMMLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune HVMMLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune SFNOLIM 2048
     # /etc/conf/bin/idtune HFNOLIM 2048

Then rebuild and reboot the kernel by issuing this command:

     # /etc/conf/bin/idbuild -B && init 6

We recommend tuning the system, but the proper parameter values to use
depend on the number of users accessing the application or database and
size the of the database (that is, the used buffer pool). The following
kernel parameters can be set with `idtune':

   * `SHMMAX' (recommended setting: 128MB) and `SHMSEG' (recommended
     setting: 15). These parameters have an influence on the MySQL
     database engine to create user buffer pools.

   * `SFNOLIM' and `HFNOLIM' should be at maximum 2048.

   * `NPROC' should be set to at least 3000/4000 (depends on number of
     users).

   * We also recommend using the following formulas to calculate values
     for `SEMMSL', `SEMMNS', and `SEMMNU':

          SEMMSL = 13

     13 is what has been found to be the best for both Progress and
     MySQL.

          SEMMNS = SEMMSL x NUMBER OF DB SERVERS TO BE RUN ON THE SYSTEM

     Set `SEMMNS' to the value of `SEMMSL' multiplied by the number of
     database servers (maximum) that you are running on the system at
     one time.

          SEMMNU = SEMMNS

     Set the value of `SEMMNU' to equal the value of `SEMMNS'. You
     could probably set this to 75% of `SEMMNS', but this is a
     conservative estimate.


File: manual.info,  Node: environment-variables,  Next: perl-support,  Prev: operating-system-specific-notes,  Up: installing

2.13 Environment Variables
==========================

This section lists all the environment variables that are used directly
or indirectly by MySQL. Most of these can also be found in other places
in this manual.

Note that any options on the command line take precedence over values
specified in option files and environment variables, and values in
option files take precedence over values in environment variables.

In many cases, it is preferable to use an option file instead of
environment variables to modify the behavior of MySQL. See *Note
option-files::.

*Variable*         *Description*
`CXX'              The name of your C++ compiler (for running
                   `configure').
`CC'               The name of your C compiler (for running `configure').
`CFLAGS'           Flags for your C compiler (for running `configure').
`CXXFLAGS'         Flags for your C++ compiler (for running `configure').
`DBI_USER'         The default user name for Perl DBI.
`DBI_TRACE'        Trace options for Perl DBI.
`HOME'             The default path for the *Note `mysql': mysql.
                   history file is `$HOME/.mysql_history'.
`LD_RUN_PATH'      Used to specify the location of `libmysqlclient.so'.
`MYSQL_DEBUG'      Debug trace options when debugging.
`MYSQL_GROUP_SUFFIX'Option group suffix value (like specifying
                   `--defaults-group-suffix').
`MYSQL_HISTFILE'   The path to the *Note `mysql': mysql. history file.
                   If this variable is set, its value overrides the
                   default for `$HOME/.mysql_history'.
`MYSQL_HOME'       The path to the directory in which the server-specific
                   `my.cnf' file resides (as of MySQL 5.0.3).
`MYSQL_HOST'       The default host name used by the *Note `mysql':
                   mysql. command-line client.
`MYSQL_PS1'        The command prompt to use in the *Note `mysql':
                   mysql. command-line client.
`MYSQL_PWD'        The default password when connecting to *Note
                   `mysqld': mysqld. Note that using this is insecure.
                   See *Note password-security-user::.
`MYSQL_TCP_PORT'   The default TCP/IP port number.
`MYSQL_UNIX_PORT'  The default Unix socket file name; used for
                   connections to `localhost'.
`PATH'             Used by the shell to find MySQL programs.
`TMPDIR'           The directory where temporary files are created.
`TZ'               This should be set to your local time zone. See *Note
                   timezone-problems::.
`UMASK'            The user-file creation mode when creating files. See
                   note following table.
`UMASK_DIR'        The user-directory creation mode when creating
                   directories. See note following table.
`USER'             The default user name on Windows and NetWare used
                   when connecting to *Note `mysqld': mysqld.

The `UMASK' and `UMASK_DIR' variables, despite their names, are used as
modes, not masks:

   * If `UMASK' is set, *Note `mysqld': mysqld.  uses `($UMASK | 0600)'
     as the mode for file creation, so that newly created files have a
     mode in the range from 0600 to 0666 (all values octal).

   * If `UMASK_DIR' is set, *Note `mysqld': mysqld. uses `($UMASK_DIR |
     0700)' as the base mode for directory creation, which then is
     AND-ed with `~(~$UMASK & 0666)', so that newly created directories
     have a mode in the range from 0700 to 0777 (all values octal). The
     AND operation may remove read and write permissions from the
     directory mode, but not execute permissions.

MySQL assumes that the value for `UMASK' or `UMASK_DIR' is in octal if
it starts with a zero.


File: manual.info,  Node: perl-support,  Prev: environment-variables,  Up: installing

2.14 Perl Installation Notes
============================

* Menu:

* perl-installation::            Installing Perl on Unix
* activestate-perl::             Installing ActiveState Perl on Windows
* perl-support-problems::        Problems Using the Perl `DBI'/`DBD' Interface

Perl support for MySQL is provided by means of the `DBI'/`DBD' client
interface.  The interface requires Perl 5.6.0, and 5.6.1 or later is
preferred. DBI _does not work_ if you have an older version of Perl.

If you want to use transactions with Perl DBI, you need to have
`DBD::mysql' 2.0900. If you are using the MySQL 4.1 or newer client
library, you must use `DBD::mysql' 2.9003 or newer. Support for
server-side prepared statements requires `DBD::mysql' 3.0009 or newer.

Perl support is not included with MySQL distributions. You can obtain
the necessary modules from `http://search.cpan.org' for Unix, or by
using the ActiveState `ppm' program on Windows. The following sections
describe how to do this.

Perl support for MySQL must be installed if you want to run the MySQL
benchmark scripts; see *Note mysql-benchmarks::.


File: manual.info,  Node: perl-installation,  Next: activestate-perl,  Prev: perl-support,  Up: perl-support

2.14.1 Installing Perl on Unix
------------------------------

MySQL Perl support requires that you have installed MySQL client
programming support (libraries and header files). Most installation
methods install the necessary files. However, if you installed MySQL
from RPM files on Linux, be sure that you've installed the developer
RPM. The client programs are in the client RPM, but client programming
support is in the developer RPM.

If you want to install Perl support, the files you need can be obtained
from the CPAN (Comprehensive Perl Archive Network) at
`http://search.cpan.org'.

The easiest way to install Perl modules on Unix is to use the `CPAN'
module. For example:

     shell> perl -MCPAN -e shell
     cpan> install DBI
     cpan> install DBD::mysql

The `DBD::mysql' installation runs a number of tests. These tests
attempt to connect to the local MySQL server using the default user
name and password. (The default user name is your login name on Unix,
and `ODBC' on Windows. The default password is `no password.') If you
cannot connect to the server with those values (for example, if your
account has a password), the tests fail. You can use `force install
DBD::mysql' to ignore the failed tests.

`DBI' requires the `Data::Dumper' module. It may be installed; if not,
you should install it before installing `DBI'.

It is also possible to download the module distributions in the form of
compressed `tar' archives and build the modules manually. For example,
to unpack and build a DBI distribution, use a procedure such as this:

  1. Unpack the distribution into the current directory:

          shell> gunzip < DBI-VERSION.tar.gz | tar xvf -

     This command creates a directory named `DBI-VERSION'.

  2. Change location into the top-level directory of the unpacked
     distribution:

          shell> cd DBI-VERSION

  3. Build the distribution and compile everything:

          shell> perl Makefile.PL
          shell> make
          shell> make test
          shell> make install

The `make test' command is important because it verifies that the
module is working. Note that when you run that command during the
`DBD::mysql' installation to exercise the interface code, the MySQL
server must be running or the test fails.

It is a good idea to rebuild and reinstall the `DBD::mysql'
distribution whenever you install a new release of MySQL, particularly
if you notice symptoms such as that all your `DBI' scripts fail after
you upgrade MySQL.

If you do not have access rights to install Perl modules in the system
directory or if you want to install local Perl modules, the following
reference may be useful:
`http://servers.digitaldaze.com/extensions/perl/modules.html#modules'

Look under the heading `Installing New Modules that Require Locally
Installed Modules.'


File: manual.info,  Node: activestate-perl,  Next: perl-support-problems,  Prev: perl-installation,  Up: perl-support

2.14.2 Installing ActiveState Perl on Windows
---------------------------------------------

On Windows, you should do the following to install the MySQL `DBD'
module with ActiveState Perl:

  1. Get ActiveState Perl from
     `http://www.activestate.com/Products/ActivePerl/' and install it.

  2. Open a console window (a `DOS window').

  3. If necessary, set the `HTTP_proxy' variable. For example, you
     might try a setting like this:

          set HTTP_proxy=my.proxy.com:3128

  4. Start the PPM program:

          C:\> C:\perl\bin\ppm.pl

  5. If you have not previously done so, install `DBI':

          ppm> install DBI

  6. If this succeeds, run the following command:

          ppm> install DBD-mysql

This procedure should work with ActiveState Perl 5.6 or newer.

If you cannot get the procedure to work, you should install the MyODBC
driver instead and connect to the MySQL server through ODBC:

     use DBI;
     $dbh= DBI->connect("DBI:ODBC:$dsn",$user,$password) ||
       die "Got error $DBI::errstr when connecting to $dsn\n";


File: manual.info,  Node: perl-support-problems,  Prev: activestate-perl,  Up: perl-support

2.14.3 Problems Using the Perl `DBI'/`DBD' Interface
----------------------------------------------------

If Perl reports that it cannot find the `../mysql/mysql.so' module, the
problem is probably that Perl cannot locate the `libmysqlclient.so'
shared library. You should be able to fix this problem by one of the
following methods:

   * Compile the `DBD::mysql' distribution with `perl Makefile.PL
     -static -config' rather than `perl Makefile.PL'.

   * Copy `libmysqlclient.so' to the directory where your other shared
     libraries are located (probably `/usr/lib' or `/lib').

   * Modify the `-L' options used to compile `DBD::mysql' to reflect
     the actual location of `libmysqlclient.so'.

   * On Linux, you can add the path name of the directory where
     `libmysqlclient.so' is located to the `/etc/ld.so.conf' file.

   * Add the path name of the directory where `libmysqlclient.so' is
     located to the `LD_RUN_PATH' environment variable. Some systems
     use `LD_LIBRARY_PATH' instead.

Note that you may also need to modify the `-L' options if there are
other libraries that the linker fails to find. For example, if the
linker cannot find `libc' because it is in `/lib' and the link command
specifies `-L/usr/lib', change the `-L' option to `-L/lib' or add
`-L/lib' to the existing link command.

If you get the following errors from `DBD::mysql', you are probably
using `gcc' (or using an old binary compiled with `gcc'):

     /usr/bin/perl: can't resolve symbol '__moddi3'
     /usr/bin/perl: can't resolve symbol '__divdi3'

Add `-L/usr/lib/gcc-lib/... -lgcc' to the link command when the
`mysql.so' library gets built (check the output from `make' for
`mysql.so' when you compile the Perl client).  The `-L' option should
specify the path name of the directory where `libgcc.a' is located on
your system.

Another cause of this problem may be that Perl and MySQL are not both
compiled with `gcc'. In this case, you can solve the mismatch by
compiling both with `gcc'.

You may see the following error from `DBD::mysql' when you run the
tests:

     t/00base............install_driver(mysql) failed:
     Can't load '../blib/arch/auto/DBD/mysql/mysql.so' for module DBD::mysql:
     ../blib/arch/auto/DBD/mysql/mysql.so: undefined symbol:
     uncompress at /usr/lib/perl5/5.00503/i586-linux/DynaLoader.pm line 169.

This means that you need to include the `-lz' compression library on
the link line. That can be done by changing the following line in the
file `lib/DBD/mysql/Install.pm':

     $sysliblist .= " -lm";

Change that line to:

     $sysliblist .= " -lm -lz";

After this, you _must_ run `make realclean' and then proceed with the
installation from the beginning.

If you want to install DBI on SCO, you have to edit the `Makefile' in
DBI-XXX and each subdirectory. Note that the following assumes `gcc'
2.95.2 or newer:

     OLD:                                  NEW:
     CC = cc                               CC = gcc
     CCCDLFLAGS = -KPIC -W1,-Bexport       CCCDLFLAGS = -fpic
     CCDLFLAGS = -wl,-Bexport              CCDLFLAGS =

     LD = ld                               LD = gcc -G -fpic
     LDDLFLAGS = -G -L/usr/local/lib       LDDLFLAGS = -L/usr/local/lib
     LDFLAGS = -belf -L/usr/local/lib      LDFLAGS = -L/usr/local/lib

     LD = ld                               LD = gcc -G -fpic
     OPTIMISE = -Od                        OPTIMISE = -O1

     OLD:
     CCCFLAGS = -belf -dy -w0 -U M_XENIX -DPERL_SCO5 -I/usr/local/include

     NEW:
     CCFLAGS = -U M_XENIX -DPERL_SCO5 -I/usr/local/include

These changes are necessary because the Perl dynaloader does not load
the `DBI' modules if they were compiled with `icc' or `cc'.

If you want to use the Perl module on a system that does not support
dynamic linking (such as SCO), you can generate a static version of
Perl that includes `DBI' and `DBD::mysql'. The way this works is that
you generate a version of Perl with the `DBI' code linked in and
install it on top of your current Perl. Then you use that to build a
version of Perl that additionally has the `DBD' code linked in, and
install that.

On SCO, you must have the following environment variables set:

     LD_LIBRARY_PATH=/lib:/usr/lib:/usr/local/lib:/usr/progressive/lib

Or:

     LD_LIBRARY_PATH=/usr/lib:/lib:/usr/local/lib:/usr/ccs/lib:\
         /usr/progressive/lib:/usr/skunk/lib
     LIBPATH=/usr/lib:/lib:/usr/local/lib:/usr/ccs/lib:\
         /usr/progressive/lib:/usr/skunk/lib
     MANPATH=scohelp:/usr/man:/usr/local1/man:/usr/local/man:\
         /usr/skunk/man:

First, create a Perl that includes a statically linked `DBI' module by
running these commands in the directory where your `DBI' distribution is
located:

     shell> perl Makefile.PL -static -config
     shell> make
     shell> make install
     shell> make perl

Then you must install the new Perl. The output of `make perl' indicates
the exact `make' command you need to execute to perform the
installation. On SCO, this is `make -f Makefile.aperl inst_perl
MAP_TARGET=perl'.

Next, use the just-created Perl to create another Perl that also
includes a statically linked `DBD::mysql' by running these commands in
the directory where your `DBD::mysql' distribution is located:

     shell> perl Makefile.PL -static -config
     shell> make
     shell> make install
     shell> make perl

Finally, you should install this new Perl. Again, the output of `make
perl' indicates the command to use.


File: manual.info,  Node: tutorial,  Next: programs,  Prev: installing,  Up: Top

3 Tutorial
**********

* Menu:

* connecting-disconnecting::     Connecting to and Disconnecting from the Server
* entering-queries::             Entering Queries
* database-use::                 Creating and Using a Database
* getting-information::          Getting Information About Databases and Tables
* batch-mode::                   Using `mysql' in Batch Mode
* examples::                     Examples of Common Queries
* twin::                         Queries from the Twin Project
* apache::                       Using MySQL with Apache

This chapter provides a tutorial introduction to MySQL by showing how
to use the *Note `mysql': mysql. client program to create and use a
simple database. *Note `mysql': mysql. (sometimes referred to as the
`terminal monitor' or just `monitor') is an interactive program that
allows you to connect to a MySQL server, run queries, and view the
results.  *Note `mysql': mysql. may also be used in batch mode: you
place your queries in a file beforehand, then tell *Note `mysql':
mysql. to execute the contents of the file. Both ways of using *Note
`mysql': mysql. are covered here.

To see a list of options provided by *Note `mysql': mysql, invoke it
with the `--help' option:

     shell> mysql --help

This chapter assumes that *Note `mysql': mysql. is installed on your
machine and that a MySQL server is available to which you can connect.
If this is not true, contact your MySQL administrator. (If _you_ are
the administrator, you need to consult the relevant portions of this
manual, such as *Note server-administration::.)

This chapter describes the entire process of setting up and using a
database. If you are interested only in accessing an existing database,
you may want to skip over the sections that describe how to create the
database and the tables it contains.

Because this chapter is tutorial in nature, many details are
necessarily omitted. Consult the relevant sections of the manual for
more information on the topics covered here.


File: manual.info,  Node: connecting-disconnecting,  Next: entering-queries,  Prev: tutorial,  Up: tutorial

3.1 Connecting to and Disconnecting from the Server
===================================================

To connect to the server, you will usually need to provide a MySQL user
name when you invoke *Note `mysql': mysql. and, most likely, a
password. If the server runs on a machine other than the one where you
log in, you will also need to specify a host name.  Contact your
administrator to find out what connection parameters you should use to
connect (that is, what host, user name, and password to use). Once you
know the proper parameters, you should be able to connect like this:

     shell> mysql -h HOST -u USER -p
     Enter password: ********

`host' and `user' represent the host name where your MySQL server is
running and the user name of your MySQL account. Substitute appropriate
values for your setup.  The `********' represents your password; enter
it when *Note `mysql': mysql. displays the `Enter password:' prompt.

If that works, you should see some introductory information followed by
a `mysql>' prompt:

     shell> mysql -h HOST -u USER -p
     Enter password: ********
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 25338 to server version: 6.0.12-standard

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql>

The `mysql>' prompt tells you that *Note `mysql': mysql. is ready for
you to enter commands.

If you are logging in on the same machine that MySQL is running on, you
can omit the host, and simply use the following:

     shell> mysql -u USER -p

If, when you attempt to log in, you get an error message such as `ERROR
2002 (HY000): Can't connect to local MySQL server through socket
'/tmp/mysql.sock' (2)', it means that that MySQL server daemon (Unix)
or service (Windows) is not running. Consult the administrator or see
the section of *Note installing:: that is appropriate to your operating
system.

For help with other problems often encountered when trying to log in,
see *Note common-errors::.

Some MySQL installations allow users to connect as the anonymous
(unnamed) user to the server running on the local host. If this is the
case on your machine, you should be able to connect to that server by
invoking *Note `mysql': mysql. without any options:

     shell> mysql

After you have connected successfully, you can disconnect any time by
typing `QUIT' (or `\q') at the `mysql>' prompt:

     mysql> QUIT
     Bye

On Unix, you can also disconnect by pressing Control-D.

Most examples in the following sections assume that you are connected
to the server. They indicate this by the `mysql>' prompt.


File: manual.info,  Node: entering-queries,  Next: database-use,  Prev: connecting-disconnecting,  Up: tutorial

3.2 Entering Queries
====================

Make sure that you are connected to the server, as discussed in the
previous section. Doing so does not in itself select any database to
work with, but that is okay. At this point, it is more important to
find out a little about how to issue queries than to jump right in
creating tables, loading data into them, and retrieving data from them.
This section describes the basic principles of entering commands, using
several queries you can try out to familiarize yourself with how *Note
`mysql': mysql.  works.

Here is a simple command that asks the server to tell you its version
number and the current date. Type it in as shown here following the
`mysql>' prompt and press Enter:

     mysql> SELECT VERSION(), CURRENT_DATE;
     +-----------------+--------------+
     | VERSION()       | CURRENT_DATE |
     +-----------------+--------------+
     | 5.1.2-alpha-log | 2005-10-11   |
     +-----------------+--------------+
     1 row in set (0.01 sec)
     mysql>

This query illustrates several things about *Note `mysql': mysql.:

   * A command normally consists of an SQL statement followed by a
     semicolon. (There are some exceptions where a semicolon may be
     omitted. `QUIT', mentioned earlier, is one of them. We'll get to
     others later.)

   * When you issue a command, *Note `mysql': mysql. sends it to the
     server for execution and displays the results, then prints another
     `mysql>' prompt to indicate that it is ready for another command.

   * *Note `mysql': mysql. displays query output in tabular form (rows
     and columns). The first row contains labels for the columns. The
     rows following are the query results. Normally, column labels are
     the names of the columns you fetch from database tables. If you're
     retrieving the value of an expression rather than a table column
     (as in the example just shown), *Note `mysql': mysql. labels the
     column using the expression itself.

   * *Note `mysql': mysql. shows how many rows were returned and how
     long the query took to execute, which gives you a rough idea of
     server performance. These values are imprecise because they
     represent wall clock time (not CPU or machine time), and because
     they are affected by factors such as server load and network
     latency. (For brevity, the `rows in set' line is sometimes not
     shown in the remaining examples in this chapter.)

Keywords may be entered in any lettercase. The following queries are
equivalent:

     mysql> SELECT VERSION(), CURRENT_DATE;
     mysql> select version(), current_date;
     mysql> SeLeCt vErSiOn(), current_DATE;

Here is another query. It demonstrates that you can use *Note `mysql':
mysql. as a simple calculator:

     mysql> SELECT SIN(PI()/4), (4+1)*5;
     +------------------+---------+
     | SIN(PI()/4)      | (4+1)*5 |
     +------------------+---------+
     | 0.70710678118655 |      25 |
     +------------------+---------+
     1 row in set (0.02 sec)

The queries shown thus far have been relatively short, single-line
statements. You can even enter multiple statements on a single line.
Just end each one with a semicolon:

     mysql> SELECT VERSION(); SELECT NOW();
     +-----------------+
     | VERSION()       |
     +-----------------+
     | 5.1.2-alpha-log |
     +-----------------+
     1 row in set (0.00 sec)

     +---------------------+
     | NOW()               |
     +---------------------+
     | 2005-10-11 15:15:00 |
     +---------------------+
     1 row in set (0.00 sec)

A command need not be given all on a single line, so lengthy commands
that require several lines are not a problem.  *Note `mysql': mysql.
determines where your statement ends by looking for the terminating
semicolon, not by looking for the end of the input line. (In other
words, *Note `mysql': mysql.  accepts free-format input: it collects
input lines but does not execute them until it sees the semicolon.)

Here is a simple multiple-line statement:

     mysql> SELECT
         -> USER()
         -> ,
         -> CURRENT_DATE;
     +---------------+--------------+
     | USER()        | CURRENT_DATE |
     +---------------+--------------+
     | jon@localhost | 2005-10-11   |
     +---------------+--------------+

In this example, notice how the prompt changes from `mysql>' to `->'
after you enter the first line of a multiple-line query. This is how
*Note `mysql': mysql. indicates that it has not yet seen a complete
statement and is waiting for the rest. The prompt is your friend,
because it provides valuable feedback. If you use that feedback, you
can always be aware of what *Note `mysql': mysql.  is waiting for.

If you decide you do not want to execute a command that you are in the
process of entering, cancel it by typing `\c':

     mysql> SELECT
         -> USER()
         -> \c
     mysql>

Here, too, notice the prompt. It switches back to `mysql>' after you
type `\c', providing feedback to indicate that *Note `mysql': mysql. is
ready for a new command.

The following table shows each of the prompts you may see and
summarizes what they mean about the state that *Note `mysql': mysql. is
in.

*Prompt**Meaning*
`mysql>'Ready for new command.
`->'    Waiting for next line of multiple-line command.
`'>'    Waiting for next line, waiting for completion of a string
        that began with a single quote (``''').
`">'    Waiting for next line, waiting for completion of a string
        that began with a double quote (``"'').
``>'    Waiting for next line, waiting for completion of an
        identifier that began with a backtick (```'').
`/*>'   Waiting for next line, waiting for completion of a
        comment that began with `/*'.

Multiple-line statements commonly occur by accident when you intend to
issue a command on a single line, but forget the terminating semicolon.
In this case, *Note `mysql': mysql.  waits for more input:

     mysql> SELECT USER()
         ->

If this happens to you (you think you've entered a statement but the
only response is a `->' prompt), most likely *Note `mysql': mysql. is
waiting for the semicolon. If you don't notice what the prompt is
telling you, you might sit there for a while before realizing what you
need to do. Enter a semicolon to complete the statement, and *Note
`mysql': mysql.  executes it:

     mysql> SELECT USER()
         -> ;
     +---------------+
     | USER()        |
     +---------------+
     | jon@localhost |
     +---------------+

The `'>' and `">' prompts occur during string collection (another way
of saying that MySQL is waiting for completion of a string). In MySQL,
you can write strings surrounded by either ``''' or ``"'' characters
(for example, `'hello'' or `"goodbye"'), and *Note `mysql': mysql. lets
you enter strings that span multiple lines. When you see a `'>' or `">'
prompt, it means that you have entered a line containing a string that
begins with a ``''' or ``"'' quote character, but have not yet entered
the matching quote that terminates the string. This often indicates
that you have inadvertently left out a quote character. For example:

     mysql> SELECT * FROM my_table WHERE name = 'Smith AND age < 30;
         '>

If you enter this *Note `SELECT': select. statement, then press `Enter'
and wait for the result, nothing happens. Instead of wondering why this
query takes so long, notice the clue provided by the `'>' prompt. It
tells you that *Note `mysql': mysql. expects to see the rest of an
unterminated string. (Do you see the error in the statement? The string
`'Smith' is missing the second single quote mark.)

At this point, what do you do? The simplest thing is to cancel the
command. However, you cannot just type `\c' in this case, because *Note
`mysql': mysql. interprets it as part of the string that it is
collecting. Instead, enter the closing quote character (so *Note
`mysql': mysql. knows you've finished the string), then type `\c':

     mysql> SELECT * FROM my_table WHERE name = 'Smith AND age < 30;
         '> '\c
     mysql>

The prompt changes back to `mysql>', indicating that *Note `mysql':
mysql. is ready for a new command.

The ``>' prompt is similar to the `'>' and `">' prompts, but indicates
that you have begun but not completed a backtick-quoted identifier.

It is important to know what the `'>', `">', and ``>' prompts signify,
because if you mistakenly enter an unterminated string, any further
lines you type appear to be ignored by *Note `mysql': mysql. --
including a line containing `QUIT'. This can be quite confusing,
especially if you do not know that you need to supply the terminating
quote before you can cancel the current command.


File: manual.info,  Node: database-use,  Next: getting-information,  Prev: entering-queries,  Up: tutorial

3.3 Creating and Using a Database
=================================

* Menu:

* creating-database::            Creating and Selecting a Database
* creating-tables::              Creating a Table
* loading-tables::               Loading Data into a Table
* retrieving-data::              Retrieving Information from a Table

Once you know how to enter commands, you are ready to access a database.

Suppose that you have several pets in your home (your menagerie) and
you would like to keep track of various types of information about
them. You can do so by creating tables to hold your data and loading
them with the desired information. Then you can answer different sorts
of questions about your animals by retrieving data from the tables.
This section shows you how to:

   * Create a database

   * Create a table

   * Load data into the table

   * Retrieve data from the table in various ways

   * Use multiple tables

The menagerie database is simple (deliberately), but it is not
difficult to think of real-world situations in which a similar type of
database might be used. For example, a database like this could be used
by a farmer to keep track of livestock, or by a veterinarian to keep
track of patient records. A menagerie distribution containing some of
the queries and sample data used in the following sections can be
obtained from the MySQL Web site.  It is available in both compressed
`tar' file and Zip formats at `http://dev.mysql.com/doc/'.

Use the *Note `SHOW': show. statement to find out what databases
currently exist on the server:

     mysql> SHOW DATABASES;
     +----------+
     | Database |
     +----------+
     | mysql    |
     | test     |
     | tmp      |
     +----------+

The `mysql' database describes user access privileges. The `test'
database often is available as a workspace for users to try things out.

The list of databases displayed by the statement may be different on
your machine; *Note `SHOW DATABASES': show-databases.  does not show
databases that you have no privileges for if you do not have the *Note
`SHOW DATABASES': show-databases.  privilege. See *Note
show-databases::.

If the `test' database exists, try to access it:

     mysql> USE test
     Database changed

Note that *Note `USE': use, like `QUIT', does not require a semicolon.
(You can terminate such statements with a semicolon if you like; it
does no harm.) The *Note `USE': use. statement is special in another
way, too: it must be given on a single line.

You can use the `test' database (if you have access to it) for the
examples that follow, but anything you create in that database can be
removed by anyone else with access to it. For this reason, you should
probably ask your MySQL administrator for permission to use a database
of your own.  Suppose that you want to call yours `menagerie'.  The
administrator needs to execute a command like this:

     mysql> GRANT ALL ON menagerie.* TO 'your_mysql_name'@'your_client_host';

where `your_mysql_name' is the MySQL user name assigned to you and
`your_client_host' is the host from which you connect to the server.


File: manual.info,  Node: creating-database,  Next: creating-tables,  Prev: database-use,  Up: database-use

3.3.1 Creating and Selecting a Database
---------------------------------------

If the administrator creates your database for you when setting up your
permissions, you can begin using it. Otherwise, you need to create it
yourself:

     mysql> CREATE DATABASE menagerie;

Under Unix, database names are case sensitive (unlike SQL keywords), so
you must always refer to your database as `menagerie', not as
`Menagerie', `MENAGERIE', or some other variant. This is also true for
table names. (Under Windows, this restriction does not apply, although
you must refer to databases and tables using the same lettercase
throughout a given query. However, for a variety of reasons, our
recommended best practice is always to use the same lettercase that was
used when the database was created.)

*Note*:

If you get an error such as `ERROR 1044 (42000): Access denied for user
'monty'@'localhost' to database 'menagerie'' when attempting to create
a database, this means that your user account does not have the
necessary privileges to do so. Discuss this with the administrator or
see *Note privilege-system::.

Creating a database does not select it for use; you must do that
explicitly. To make `menagerie' the current database, use this command:

     mysql> USE menagerie
     Database changed

Your database needs to be created only once, but you must select it for
use each time you begin a *Note `mysql': mysql.  session. You can do
this by issuing a *Note `USE': use. statement as shown in the example.
Alternatively, you can select the database on the command line when you
invoke *Note `mysql': mysql. Just specify its name after any connection
parameters that you might need to provide. For example:

     shell> mysql -h HOST -u USER -p menagerie
     Enter password: ********

Note that `menagerie' in the command just shown is *not* your password.
If you want to supply your password on the command line after the `-p'
option, you must do so with no intervening space (for example, as
`-pmypassword', not as `-p mypassword'). However, putting your password
on the command line is not recommended, because doing so exposes it to
snooping by other users logged in on your machine.


File: manual.info,  Node: creating-tables,  Next: loading-tables,  Prev: creating-database,  Up: database-use

3.3.2 Creating a Table
----------------------

Creating the database is the easy part, but at this point it is empty,
as *Note `SHOW TABLES': show-tables. tells you:

     mysql> SHOW TABLES;
     Empty set (0.00 sec)

The harder part is deciding what the structure of your database should
be: what tables you need and what columns should be in each of them.

You want a table that contains a record for each of your pets.  This
can be called the `pet' table, and it should contain, as a bare
minimum, each animal's name. Because the name by itself is not very
interesting, the table should contain other information. For example,
if more than one person in your family keeps pets, you might want to
list each animal's owner. You might also want to record some basic
descriptive information such as species and sex.

How about age? That might be of interest, but it is not a good thing to
store in a database. Age changes as time passes, which means you'd have
to update your records often. Instead, it is better to store a fixed
value such as date of birth. Then, whenever you need age, you can
calculate it as the difference between the current date and the birth
date. MySQL provides functions for doing date arithmetic, so this is
not difficult.  Storing birth date rather than age has other
advantages, too:

   * You can use the database for tasks such as generating reminders
     for upcoming pet birthdays. (If you think this type of query is
     somewhat silly, note that it is the same question you might ask in
     the context of a business database to identify clients to whom you
     need to send out birthday greetings in the current week or month,
     for that computer-assisted personal touch.)

   * You can calculate age in relation to dates other than the current
     date. For example, if you store death date in the database, you
     can easily calculate how old a pet was when it died.

You can probably think of other types of information that would be
useful in the `pet' table, but the ones identified so far are
sufficient: name, owner, species, sex, birth, and death.

Use a *Note `CREATE TABLE': create-table. statement to specify the
layout of your table:

     mysql> CREATE TABLE pet (name VARCHAR(20), owner VARCHAR(20),
         -> species VARCHAR(20), sex CHAR(1), birth DATE, death DATE);

*Note `VARCHAR': char. is a good choice for the `name', `owner', and
`species' columns because the column values vary in length. The lengths
in those column definitions need not all be the same, and need not be
`20'. You can normally pick any length from `1' to `65535', whatever
seems most reasonable to you.  If you make a poor choice and it turns
out later that you need a longer field, MySQL provides an *Note `ALTER
TABLE': alter-table. statement.

Several types of values can be chosen to represent sex in animal
records, such as `'m'' and `'f'', or perhaps `'male'' and `'female''.
It is simplest to use the single characters `'m'' and `'f''.

The use of the *Note `DATE': datetime. data type for the `birth' and
`death' columns is a fairly obvious choice.

Once you have created a table, *Note `SHOW TABLES': show-tables. should
produce some output:

     mysql> SHOW TABLES;
     +---------------------+
     | Tables in menagerie |
     +---------------------+
     | pet                 |
     +---------------------+

To verify that your table was created the way you expected, use a *Note
`DESCRIBE': describe. statement:

     mysql> DESCRIBE pet;
     +---------+-------------+------+-----+---------+-------+
     | Field   | Type        | Null | Key | Default | Extra |
     +---------+-------------+------+-----+---------+-------+
     | name    | varchar(20) | YES  |     | NULL    |       |
     | owner   | varchar(20) | YES  |     | NULL    |       |
     | species | varchar(20) | YES  |     | NULL    |       |
     | sex     | char(1)     | YES  |     | NULL    |       |
     | birth   | date        | YES  |     | NULL    |       |
     | death   | date        | YES  |     | NULL    |       |
     +---------+-------------+------+-----+---------+-------+

You can use *Note `DESCRIBE': describe. any time, for example, if you
forget the names of the columns in your table or what types they have.

For more information about MySQL data types, see *Note data-types::.


File: manual.info,  Node: loading-tables,  Next: retrieving-data,  Prev: creating-tables,  Up: database-use

3.3.3 Loading Data into a Table
-------------------------------

After creating your table, you need to populate it. The *Note `LOAD
DATA': load-data. and *Note `INSERT': insert. statements are useful for
this.

Suppose that your pet records can be described as shown here.  (Observe
that MySQL expects dates in `'YYYY-MM-DD'' format; this may be different
from what you are used to.)

*name*  *owner* *species**sex**birth*        *death*
Fluffy  Harold  cat     f    1993-02-04     
Claws   Gwen    cat     m    1994-03-17     
Buffy   Harold  dog     f    1989-05-13     
Fang    Benny   dog     m    1990-08-27     
Bowser  Diane   dog     m    1979-08-31     1995-07-29
Chirpy  Gwen    bird    f    1998-09-11     
WhistlerGwen    bird         1997-12-09     
Slim    Benny   snake   m    1996-04-29     

Because you are beginning with an empty table, an easy way to populate
it is to create a text file containing a row for each of your animals,
then load the contents of the file into the table with a single
statement.

You could create a text file `pet.txt' containing one record per line,
with values separated by tabs, and given in the order in which the
columns were listed in the *Note `CREATE TABLE': create-table.
statement. For missing values (such as unknown sexes or death dates for
animals that are still living), you can use `NULL' values. To represent
these in your text file, use `\N' (backslash, capital-N). For example,
the record for Whistler the bird would look like this (where the
whitespace between values is a single tab character):

     Whistler        Gwen    bird    \N      1997-12-09      \N

To load the text file `pet.txt' into the `pet' table, use this command:

     mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet;

Note that if you created the file on Windows with an editor that uses
`\r\n' as a line terminator, you should use:

     mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet
         -> LINES TERMINATED BY '\r\n';

(On an Apple machine running OS X, you would likely want to use `LINES
TERMINATED BY '\r''.)

You can specify the column value separator and end of line marker
explicitly in the *Note `LOAD DATA': load-data. statement if you wish,
but the defaults are tab and linefeed. These are sufficient for the
statement to read the file `pet.txt' properly.

If the statement fails, it is likely that your MySQL installation does
not have local file capability enabled by default. See *Note
load-data-local::, for information on how to change this.

When you want to add new records one at a time, the *Note `INSERT':
insert. statement is useful. In its simplest form, you supply values
for each column, in the order in which the columns were listed in the
*Note `CREATE TABLE': create-table. statement. Suppose that Diane gets
a new hamster named `Puffball.' You could add a new record using an
*Note `INSERT': insert. statement like this:

     mysql> INSERT INTO pet
         -> VALUES ('Puffball','Diane','hamster','f','1999-03-30',NULL);

Note that string and date values are specified as quoted strings here.
Also, with *Note `INSERT': insert, you can insert `NULL' directly to
represent a missing value. You do not use `\N' like you do with *Note
`LOAD DATA': load-data.

From this example, you should be able to see that there would be a lot
more typing involved to load your records initially using several *Note
`INSERT': insert. statements rather than a single *Note `LOAD DATA':
load-data.  statement.


File: manual.info,  Node: retrieving-data,  Prev: loading-tables,  Up: database-use

3.3.4 Retrieving Information from a Table
-----------------------------------------

* Menu:

* selecting-all::                Selecting All Data
* selecting-rows::               Selecting Particular Rows
* selecting-columns::            Selecting Particular Columns
* sorting-rows::                 Sorting Rows
* date-calculations::            Date Calculations
* working-with-null::            Working with `NULL' Values
* pattern-matching::             Pattern Matching
* counting-rows::                Counting Rows
* multiple-tables::              Using More Than one Table

The *Note `SELECT': select. statement is used to pull information from
a table. The general form of the statement is:

     SELECT WHAT_TO_SELECT
     FROM WHICH_TABLE
     WHERE CONDITIONS_TO_SATISFY;

WHAT_TO_SELECT indicates what you want to see. This can be a list of
columns, or `*' to indicate `all columns.' WHICH_TABLE indicates the
table from which you want to retrieve data. The `WHERE' clause is
optional. If it is present, CONDITIONS_TO_SATISFY specifies one or more
conditions that rows must satisfy to qualify for retrieval.


File: manual.info,  Node: selecting-all,  Next: selecting-rows,  Prev: retrieving-data,  Up: retrieving-data

3.3.4.1 Selecting All Data
..........................

The simplest form of *Note `SELECT': select.  retrieves everything from
a table:

     mysql> SELECT * FROM pet;
     +----------+--------+---------+------+------------+------------+
     | name     | owner  | species | sex  | birth      | death      |
     +----------+--------+---------+------+------------+------------+
     | Fluffy   | Harold | cat     | f    | 1993-02-04 | NULL       |
     | Claws    | Gwen   | cat     | m    | 1994-03-17 | NULL       |
     | Buffy    | Harold | dog     | f    | 1989-05-13 | NULL       |
     | Fang     | Benny  | dog     | m    | 1990-08-27 | NULL       |
     | Bowser   | Diane  | dog     | m    | 1979-08-31 | 1995-07-29 |
     | Chirpy   | Gwen   | bird    | f    | 1998-09-11 | NULL       |
     | Whistler | Gwen   | bird    | NULL | 1997-12-09 | NULL       |
     | Slim     | Benny  | snake   | m    | 1996-04-29 | NULL       |
     | Puffball | Diane  | hamster | f    | 1999-03-30 | NULL       |
     +----------+--------+---------+------+------------+------------+

This form of *Note `SELECT': select. is useful if you want to review
your entire table, for example, after you've just loaded it with your
initial data set. For example, you may happen to think that the birth
date for Bowser doesn't seem quite right. Consulting your original
pedigree papers, you find that the correct birth year should be 1989,
not 1979.

There are at least two ways to fix this:

   * Edit the file `pet.txt' to correct the error, then empty the table
     and reload it using *Note `DELETE': delete. and *Note `LOAD DATA':
     load-data.:

          mysql> DELETE FROM pet;
          mysql> LOAD DATA LOCAL INFILE 'pet.txt' INTO TABLE pet;

     However, if you do this, you must also re-enter the record for
     Puffball.

   * Fix only the erroneous record with an *Note `UPDATE': update.
     statement:

          mysql> UPDATE pet SET birth = '1989-08-31' WHERE name = 'Bowser';

     The *Note `UPDATE': update. changes only the record in question
     and does not require you to reload the table.


File: manual.info,  Node: selecting-rows,  Next: selecting-columns,  Prev: selecting-all,  Up: retrieving-data

3.3.4.2 Selecting Particular Rows
.................................

As shown in the preceding section, it is easy to retrieve an entire
table. Just omit the `WHERE' clause from the *Note `SELECT': select.
statement. But typically you don't want to see the entire table,
particularly when it becomes large. Instead, you're usually more
interested in answering a particular question, in which case you specify
some constraints on the information you want. Let's look at some
selection queries in terms of questions about your pets that they
answer.

You can select only particular rows from your table. For example, if
you want to verify the change that you made to Bowser's birth date,
select Bowser's record like this:

     mysql> SELECT * FROM pet WHERE name = 'Bowser';
     +--------+-------+---------+------+------------+------------+
     | name   | owner | species | sex  | birth      | death      |
     +--------+-------+---------+------+------------+------------+
     | Bowser | Diane | dog     | m    | 1989-08-31 | 1995-07-29 |
     +--------+-------+---------+------+------------+------------+

The output confirms that the year is correctly recorded as 1989, not
1979.

String comparisons normally are case-insensitive, so you can specify
the name as `'bowser'', `'BOWSER'', and so forth. The query result is
the same.

You can specify conditions on any column, not just `name'. For example,
if you want to know which animals were born during or after 1998, test
the `birth' column:

     mysql> SELECT * FROM pet WHERE birth >= '1998-1-1';
     +----------+-------+---------+------+------------+-------+
     | name     | owner | species | sex  | birth      | death |
     +----------+-------+---------+------+------------+-------+
     | Chirpy   | Gwen  | bird    | f    | 1998-09-11 | NULL  |
     | Puffball | Diane | hamster | f    | 1999-03-30 | NULL  |
     +----------+-------+---------+------+------------+-------+

You can combine conditions, for example, to locate female dogs:

     mysql> SELECT * FROM pet WHERE species = 'dog' AND sex = 'f';
     +-------+--------+---------+------+------------+-------+
     | name  | owner  | species | sex  | birth      | death |
     +-------+--------+---------+------+------------+-------+
     | Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
     +-------+--------+---------+------+------------+-------+

The preceding query uses the `AND' logical operator. There is also an
`OR' operator:

     mysql> SELECT * FROM pet WHERE species = 'snake' OR species = 'bird';
     +----------+-------+---------+------+------------+-------+
     | name     | owner | species | sex  | birth      | death |
     +----------+-------+---------+------+------------+-------+
     | Chirpy   | Gwen  | bird    | f    | 1998-09-11 | NULL  |
     | Whistler | Gwen  | bird    | NULL | 1997-12-09 | NULL  |
     | Slim     | Benny | snake   | m    | 1996-04-29 | NULL  |
     +----------+-------+---------+------+------------+-------+

`AND' and `OR' may be intermixed, although `AND' has higher precedence
than `OR'. If you use both operators, it is a good idea to use
parentheses to indicate explicitly how conditions should be grouped:

     mysql> SELECT * FROM pet WHERE (species = 'cat' AND sex = 'm')
         -> OR (species = 'dog' AND sex = 'f');
     +-------+--------+---------+------+------------+-------+
     | name  | owner  | species | sex  | birth      | death |
     +-------+--------+---------+------+------------+-------+
     | Claws | Gwen   | cat     | m    | 1994-03-17 | NULL  |
     | Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
     +-------+--------+---------+------+------------+-------+


File: manual.info,  Node: selecting-columns,  Next: sorting-rows,  Prev: selecting-rows,  Up: retrieving-data

3.3.4.3 Selecting Particular Columns
....................................

If you do not want to see entire rows from your table, just name the
columns in which you are interested, separated by commas. For example,
if you want to know when your animals were born, select the `name' and
`birth' columns:

     mysql> SELECT name, birth FROM pet;
     +----------+------------+
     | name     | birth      |
     +----------+------------+
     | Fluffy   | 1993-02-04 |
     | Claws    | 1994-03-17 |
     | Buffy    | 1989-05-13 |
     | Fang     | 1990-08-27 |
     | Bowser   | 1989-08-31 |
     | Chirpy   | 1998-09-11 |
     | Whistler | 1997-12-09 |
     | Slim     | 1996-04-29 |
     | Puffball | 1999-03-30 |
     +----------+------------+

To find out who owns pets, use this query:

     mysql> SELECT owner FROM pet;
     +--------+
     | owner  |
     +--------+
     | Harold |
     | Gwen   |
     | Harold |
     | Benny  |
     | Diane  |
     | Gwen   |
     | Gwen   |
     | Benny  |
     | Diane  |
     +--------+

Notice that the query simply retrieves the `owner' column from each
record, and some of them appear more than once. To minimize the output,
retrieve each unique output record just once by adding the keyword
`DISTINCT':

     mysql> SELECT DISTINCT owner FROM pet;
     +--------+
     | owner  |
     +--------+
     | Benny  |
     | Diane  |
     | Gwen   |
     | Harold |
     +--------+

You can use a `WHERE' clause to combine row selection with column
selection. For example, to get birth dates for dogs and cats only, use
this query:

     mysql> SELECT name, species, birth FROM pet
         -> WHERE species = 'dog' OR species = 'cat';
     +--------+---------+------------+
     | name   | species | birth      |
     +--------+---------+------------+
     | Fluffy | cat     | 1993-02-04 |
     | Claws  | cat     | 1994-03-17 |
     | Buffy  | dog     | 1989-05-13 |
     | Fang   | dog     | 1990-08-27 |
     | Bowser | dog     | 1989-08-31 |
     +--------+---------+------------+


File: manual.info,  Node: sorting-rows,  Next: date-calculations,  Prev: selecting-columns,  Up: retrieving-data

3.3.4.4 Sorting Rows
....................

You may have noticed in the preceding examples that the result rows are
displayed in no particular order. It is often easier to examine query
output when the rows are sorted in some meaningful way. To sort a
result, use an `ORDER BY' clause.

Here are animal birthdays, sorted by date:

     mysql> SELECT name, birth FROM pet ORDER BY birth;
     +----------+------------+
     | name     | birth      |
     +----------+------------+
     | Buffy    | 1989-05-13 |
     | Bowser   | 1989-08-31 |
     | Fang     | 1990-08-27 |
     | Fluffy   | 1993-02-04 |
     | Claws    | 1994-03-17 |
     | Slim     | 1996-04-29 |
     | Whistler | 1997-12-09 |
     | Chirpy   | 1998-09-11 |
     | Puffball | 1999-03-30 |
     +----------+------------+

On character type columns, sorting -- like all other comparison
operations -- is normally performed in a case-insensitive fashion. This
means that the order is undefined for columns that are identical except
for their case. You can force a case-sensitive sort for a column by
using `BINARY' like so: `ORDER BY BINARY COL_NAME'.

The default sort order is ascending, with smallest values first. To
sort in reverse (descending) order, add the `DESC' keyword to the name
of the column you are sorting by:

     mysql> SELECT name, birth FROM pet ORDER BY birth DESC;
     +----------+------------+
     | name     | birth      |
     +----------+------------+
     | Puffball | 1999-03-30 |
     | Chirpy   | 1998-09-11 |
     | Whistler | 1997-12-09 |
     | Slim     | 1996-04-29 |
     | Claws    | 1994-03-17 |
     | Fluffy   | 1993-02-04 |
     | Fang     | 1990-08-27 |
     | Bowser   | 1989-08-31 |
     | Buffy    | 1989-05-13 |
     +----------+------------+

You can sort on multiple columns, and you can sort different columns in
different directions. For example, to sort by type of animal in
ascending order, then by birth date within animal type in descending
order (youngest animals first), use the following query:

     mysql> SELECT name, species, birth FROM pet
         -> ORDER BY species, birth DESC;
     +----------+---------+------------+
     | name     | species | birth      |
     +----------+---------+------------+
     | Chirpy   | bird    | 1998-09-11 |
     | Whistler | bird    | 1997-12-09 |
     | Claws    | cat     | 1994-03-17 |
     | Fluffy   | cat     | 1993-02-04 |
     | Fang     | dog     | 1990-08-27 |
     | Bowser   | dog     | 1989-08-31 |
     | Buffy    | dog     | 1989-05-13 |
     | Puffball | hamster | 1999-03-30 |
     | Slim     | snake   | 1996-04-29 |
     +----------+---------+------------+

Note that the `DESC' keyword applies only to the column name
immediately preceding it (`birth'); it does not affect the `species'
column sort order.


File: manual.info,  Node: date-calculations,  Next: working-with-null,  Prev: sorting-rows,  Up: retrieving-data

3.3.4.5 Date Calculations
.........................

MySQL provides several functions that you can use to perform
calculations on dates, for example, to calculate ages or extract parts
of dates.

To determine how many years old each of your pets is, compute the
difference in the year part of the current date and the birth date,
then subtract one if the current date occurs earlier in the calendar
year than the birth date. The following query shows, for each pet, the
birth date, the current date, and the age in years.

     mysql> SELECT name, birth, CURDATE(),
         -> (YEAR(CURDATE())-YEAR(birth))
         -> - (RIGHT(CURDATE(),5)<RIGHT(birth,5))
         -> AS age
         -> FROM pet;
     +----------+------------+------------+------+
     | name     | birth      | CURDATE()  | age  |
     +----------+------------+------------+------+
     | Fluffy   | 1993-02-04 | 2003-08-19 |   10 |
     | Claws    | 1994-03-17 | 2003-08-19 |    9 |
     | Buffy    | 1989-05-13 | 2003-08-19 |   14 |
     | Fang     | 1990-08-27 | 2003-08-19 |   12 |
     | Bowser   | 1989-08-31 | 2003-08-19 |   13 |
     | Chirpy   | 1998-09-11 | 2003-08-19 |    4 |
     | Whistler | 1997-12-09 | 2003-08-19 |    5 |
     | Slim     | 1996-04-29 | 2003-08-19 |    7 |
     | Puffball | 1999-03-30 | 2003-08-19 |    4 |
     +----------+------------+------------+------+

Here, `YEAR()' pulls out the year part of a date and `RIGHT()' pulls
off the rightmost five characters that represent the `MM-DD' (calendar
year) part of the date. The part of the expression that compares the
`MM-DD' values evaluates to 1 or 0, which adjusts the year difference
down a year if `CURDATE()' occurs earlier in the year than `birth'. The
full expression is somewhat ungainly, so an _alias_ (`age') is used to
make the output column label more meaningful.

The query works, but the result could be scanned more easily if the
rows were presented in some order. This can be done by adding an `ORDER
BY name' clause to sort the output by name:

     mysql> SELECT name, birth, CURDATE(),
         -> (YEAR(CURDATE())-YEAR(birth))
         -> - (RIGHT(CURDATE(),5)<RIGHT(birth,5))
         -> AS age
         -> FROM pet ORDER BY name;
     +----------+------------+------------+------+
     | name     | birth      | CURDATE()  | age  |
     +----------+------------+------------+------+
     | Bowser   | 1989-08-31 | 2003-08-19 |   13 |
     | Buffy    | 1989-05-13 | 2003-08-19 |   14 |
     | Chirpy   | 1998-09-11 | 2003-08-19 |    4 |
     | Claws    | 1994-03-17 | 2003-08-19 |    9 |
     | Fang     | 1990-08-27 | 2003-08-19 |   12 |
     | Fluffy   | 1993-02-04 | 2003-08-19 |   10 |
     | Puffball | 1999-03-30 | 2003-08-19 |    4 |
     | Slim     | 1996-04-29 | 2003-08-19 |    7 |
     | Whistler | 1997-12-09 | 2003-08-19 |    5 |
     +----------+------------+------------+------+

To sort the output by `age' rather than `name', just use a different
`ORDER BY' clause:

     mysql> SELECT name, birth, CURDATE(),
         -> (YEAR(CURDATE())-YEAR(birth))
         -> - (RIGHT(CURDATE(),5)<RIGHT(birth,5))
         -> AS age
         -> FROM pet ORDER BY age;
     +----------+------------+------------+------+
     | name     | birth      | CURDATE()  | age  |
     +----------+------------+------------+------+
     | Chirpy   | 1998-09-11 | 2003-08-19 |    4 |
     | Puffball | 1999-03-30 | 2003-08-19 |    4 |
     | Whistler | 1997-12-09 | 2003-08-19 |    5 |
     | Slim     | 1996-04-29 | 2003-08-19 |    7 |
     | Claws    | 1994-03-17 | 2003-08-19 |    9 |
     | Fluffy   | 1993-02-04 | 2003-08-19 |   10 |
     | Fang     | 1990-08-27 | 2003-08-19 |   12 |
     | Bowser   | 1989-08-31 | 2003-08-19 |   13 |
     | Buffy    | 1989-05-13 | 2003-08-19 |   14 |
     +----------+------------+------------+------+

A similar query can be used to determine age at death for animals that
have died. You determine which animals these are by checking whether
the `death' value is `NULL'. Then, for those with non-`NULL' values,
compute the difference between the `death' and `birth' values:

     mysql> SELECT name, birth, death,
         -> (YEAR(death)-YEAR(birth)) - (RIGHT(death,5)<RIGHT(birth,5))
         -> AS age
         -> FROM pet WHERE death IS NOT NULL ORDER BY age;
     +--------+------------+------------+------+
     | name   | birth      | death      | age  |
     +--------+------------+------------+------+
     | Bowser | 1989-08-31 | 1995-07-29 |    5 |
     +--------+------------+------------+------+

The query uses `death IS NOT NULL' rather than `death <> NULL' because
`NULL' is a special value that cannot be compared using the usual
comparison operators. This is discussed later. See *Note
working-with-null::.

What if you want to know which animals have birthdays next month? For
this type of calculation, year and day are irrelevant; you simply want
to extract the month part of the `birth' column. MySQL provides several
functions for extracting parts of dates, such as `YEAR()', `MONTH()',
and `DAYOFMONTH()'.  `MONTH()' is the appropriate function here. To see
how it works, run a simple query that displays the value of both
`birth' and `MONTH(birth)':

     mysql> SELECT name, birth, MONTH(birth) FROM pet;
     +----------+------------+--------------+
     | name     | birth      | MONTH(birth) |
     +----------+------------+--------------+
     | Fluffy   | 1993-02-04 |            2 |
     | Claws    | 1994-03-17 |            3 |
     | Buffy    | 1989-05-13 |            5 |
     | Fang     | 1990-08-27 |            8 |
     | Bowser   | 1989-08-31 |            8 |
     | Chirpy   | 1998-09-11 |            9 |
     | Whistler | 1997-12-09 |           12 |
     | Slim     | 1996-04-29 |            4 |
     | Puffball | 1999-03-30 |            3 |
     +----------+------------+--------------+

Finding animals with birthdays in the upcoming month is also simple.
Suppose that the current month is April. Then the month value is `4'
and you can look for animals born in May (month `5') like this:

     mysql> SELECT name, birth FROM pet WHERE MONTH(birth) = 5;
     +-------+------------+
     | name  | birth      |
     +-------+------------+
     | Buffy | 1989-05-13 |
     +-------+------------+

There is a small complication if the current month is December. You
cannot merely add one to the month number (`12') and look for animals
born in month `13', because there is no such month.  Instead, you look
for animals born in January (month `1').

You can write the query so that it works no matter what the current
month is, so that you do not have to use the number for a particular
month.  `DATE_ADD()' allows you to add a time interval to a given date.
If you add a month to the value of `CURDATE()', then extract the month
part with `MONTH()', the result produces the month in which to look for
birthdays:

     mysql> SELECT name, birth FROM pet
         -> WHERE MONTH(birth) = MONTH(DATE_ADD(CURDATE(),INTERVAL 1 MONTH));

A different way to accomplish the same task is to add `1' to get the
next month after the current one after using the modulo function (`MOD')
to wrap the month value to `0' if it is currently `12':

     mysql> SELECT name, birth FROM pet
         -> WHERE MONTH(birth) = MOD(MONTH(CURDATE()), 12) + 1;

Note that `MONTH()' returns a number between `1' and `12'.  And
`MOD(something,12)' returns a number between `0' and `11'.  So the
addition has to be after the `MOD()', otherwise we would go from
November (`11') to January (`1').


File: manual.info,  Node: working-with-null,  Next: pattern-matching,  Prev: date-calculations,  Up: retrieving-data

3.3.4.6 Working with `NULL' Values
..................................

The `NULL' value can be surprising until you get used to it.
Conceptually, `NULL' means `a missing unknown value' and it is treated
somewhat differently from other values. To test for `NULL', you cannot
use the arithmetic comparison operators such as `=', `<', or `<>'. To
demonstrate this for yourself, try the following query:

     mysql> SELECT 1 = NULL, 1 <> NULL, 1 < NULL, 1 > NULL;
     +----------+-----------+----------+----------+
     | 1 = NULL | 1 <> NULL | 1 < NULL | 1 > NULL |
     +----------+-----------+----------+----------+
     |     NULL |      NULL |     NULL |     NULL |
     +----------+-----------+----------+----------+

Clearly you get no meaningful results from these comparisons.  Use the
`IS NULL' and `IS NOT NULL' operators instead:

     mysql> SELECT 1 IS NULL, 1 IS NOT NULL;
     +-----------+---------------+
     | 1 IS NULL | 1 IS NOT NULL |
     +-----------+---------------+
     |         0 |             1 |
     +-----------+---------------+

Note that in MySQL, `0' or `NULL' means false and anything else means
true. The default truth value from a boolean operation is `1'.

This special treatment of `NULL' is why, in the previous section, it
was necessary to determine which animals are no longer alive using
`death IS NOT NULL' instead of `death <> NULL'.

Two `NULL' values are regarded as equal in a `GROUP BY'.

When doing an `ORDER BY', `NULL' values are presented first if you do
`ORDER BY ... ASC' and last if you do `ORDER BY ... DESC'.

A common error when working with `NULL' is to assume that it is not
possible to insert a zero or an empty string into a column defined as
`NOT NULL', but this is not the case. These are in fact values, whereas
`NULL' means `not having a value.' You can test this easily enough by
using `IS '[`NOT']` NULL' as shown:

     mysql> SELECT 0 IS NULL, 0 IS NOT NULL, '' IS NULL, '' IS NOT NULL;
     +-----------+---------------+------------+----------------+
     | 0 IS NULL | 0 IS NOT NULL | '' IS NULL | '' IS NOT NULL |
     +-----------+---------------+------------+----------------+
     |         0 |             1 |          0 |              1 |
     +-----------+---------------+------------+----------------+

Thus it is entirely possible to insert a zero or empty string into a
`NOT NULL' column, as these are in fact `NOT NULL'. See *Note
problems-with-null::.


File: manual.info,  Node: pattern-matching,  Next: counting-rows,  Prev: working-with-null,  Up: retrieving-data

3.3.4.7 Pattern Matching
........................

MySQL provides standard SQL pattern matching as well as a form of
pattern matching based on extended regular expressions similar to those
used by Unix utilities such as `vi', `grep', and `sed'.

SQL pattern matching allows you to use ``_'' to match any single
character and ``%'' to match an arbitrary number of characters
(including zero characters). In MySQL, SQL patterns are
case-insensitive by default. Some examples are shown here. Note that
you do not use `=' or `<>' when you use SQL patterns; use the `LIKE' or
`NOT LIKE' comparison operators instead.

To find names beginning with ``b'':

     mysql> SELECT * FROM pet WHERE name LIKE 'b%';
     +--------+--------+---------+------+------------+------------+
     | name   | owner  | species | sex  | birth      | death      |
     +--------+--------+---------+------+------------+------------+
     | Buffy  | Harold | dog     | f    | 1989-05-13 | NULL       |
     | Bowser | Diane  | dog     | m    | 1989-08-31 | 1995-07-29 |
     +--------+--------+---------+------+------------+------------+

To find names ending with ``fy'':

     mysql> SELECT * FROM pet WHERE name LIKE '%fy';
     +--------+--------+---------+------+------------+-------+
     | name   | owner  | species | sex  | birth      | death |
     +--------+--------+---------+------+------------+-------+
     | Fluffy | Harold | cat     | f    | 1993-02-04 | NULL  |
     | Buffy  | Harold | dog     | f    | 1989-05-13 | NULL  |
     +--------+--------+---------+------+------------+-------+

To find names containing a ``w'':

     mysql> SELECT * FROM pet WHERE name LIKE '%w%';
     +----------+-------+---------+------+------------+------------+
     | name     | owner | species | sex  | birth      | death      |
     +----------+-------+---------+------+------------+------------+
     | Claws    | Gwen  | cat     | m    | 1994-03-17 | NULL       |
     | Bowser   | Diane | dog     | m    | 1989-08-31 | 1995-07-29 |
     | Whistler | Gwen  | bird    | NULL | 1997-12-09 | NULL       |
     +----------+-------+---------+------+------------+------------+

To find names containing exactly five characters, use five instances of
the ``_'' pattern character:

     mysql> SELECT * FROM pet WHERE name LIKE '_____';
     +-------+--------+---------+------+------------+-------+
     | name  | owner  | species | sex  | birth      | death |
     +-------+--------+---------+------+------------+-------+
     | Claws | Gwen   | cat     | m    | 1994-03-17 | NULL  |
     | Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
     +-------+--------+---------+------+------------+-------+

The other type of pattern matching provided by MySQL uses extended
regular expressions. When you test for a match for this type of
pattern, use the `REGEXP' and `NOT REGEXP' operators (or `RLIKE' and
`NOT RLIKE', which are synonyms).

Some characteristics of extended regular expressions are:

   * ``.'' matches any single character.

   * A character class ``[...]'' matches any character within the
     brackets. For example, ``[abc]'' matches ``a'', ``b'', or ``c''.
     To name a range of characters, use a dash.  ``[a-z]'' matches any
     letter, whereas ``[0-9]'' matches any digit.

   * ``*'' matches zero or more instances of the thing preceding it.
     For example, ``x*'' matches any number of ``x'' characters,
     ``[0-9]*'' matches any number of digits, and ``.*'' matches any
     number of anything.

   * A `REGEXP' pattern match succeeds if the pattern matches anywhere
     in the value being tested. (This differs from a `LIKE' pattern
     match, which succeeds only if the pattern matches the entire
     value.)

   * To anchor a pattern so that it must match the beginning or end of
     the value being tested, use ``^'' at the beginning or ``$'' at the
     end of the pattern.

To demonstrate how extended regular expressions work, the `LIKE'
queries shown previously are rewritten here to use `REGEXP'.

To find names beginning with ``b'', use ``^'' to match the beginning of
the name:

     mysql> SELECT * FROM pet WHERE name REGEXP '^b';
     +--------+--------+---------+------+------------+------------+
     | name   | owner  | species | sex  | birth      | death      |
     +--------+--------+---------+------+------------+------------+
     | Buffy  | Harold | dog     | f    | 1989-05-13 | NULL       |
     | Bowser | Diane  | dog     | m    | 1989-08-31 | 1995-07-29 |
     +--------+--------+---------+------+------------+------------+

If you really want to force a `REGEXP' comparison to be case sensitive,
use the `BINARY' keyword to make one of the strings a binary string.
This query matches only lowercase ``b'' at the beginning of a name:

     mysql> SELECT * FROM pet WHERE name REGEXP BINARY '^b';

To find names ending with ``fy'', use ``$'' to match the end of the
name:

     mysql> SELECT * FROM pet WHERE name REGEXP 'fy$';
     +--------+--------+---------+------+------------+-------+
     | name   | owner  | species | sex  | birth      | death |
     +--------+--------+---------+------+------------+-------+
     | Fluffy | Harold | cat     | f    | 1993-02-04 | NULL  |
     | Buffy  | Harold | dog     | f    | 1989-05-13 | NULL  |
     +--------+--------+---------+------+------------+-------+

To find names containing a ``w'', use this query:

     mysql> SELECT * FROM pet WHERE name REGEXP 'w';
     +----------+-------+---------+------+------------+------------+
     | name     | owner | species | sex  | birth      | death      |
     +----------+-------+---------+------+------------+------------+
     | Claws    | Gwen  | cat     | m    | 1994-03-17 | NULL       |
     | Bowser   | Diane | dog     | m    | 1989-08-31 | 1995-07-29 |
     | Whistler | Gwen  | bird    | NULL | 1997-12-09 | NULL       |
     +----------+-------+---------+------+------------+------------+

Because a regular expression pattern matches if it occurs anywhere in
the value, it is not necessary in the previous query to put a wildcard
on either side of the pattern to get it to match the entire value like
it would be if you used an SQL pattern.

To find names containing exactly five characters, use ``^'' and ``$''
to match the beginning and end of the name, and five instances of ``.''
in between:

     mysql> SELECT * FROM pet WHERE name REGEXP '^.....$';
     +-------+--------+---------+------+------------+-------+
     | name  | owner  | species | sex  | birth      | death |
     +-------+--------+---------+------+------------+-------+
     | Claws | Gwen   | cat     | m    | 1994-03-17 | NULL  |
     | Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
     +-------+--------+---------+------+------------+-------+

You could also write the previous query using the `{N}'
(`repeat-N-times') operator:

     mysql> SELECT * FROM pet WHERE name REGEXP '^.{5}$';
     +-------+--------+---------+------+------------+-------+
     | name  | owner  | species | sex  | birth      | death |
     +-------+--------+---------+------+------------+-------+
     | Claws | Gwen   | cat     | m    | 1994-03-17 | NULL  |
     | Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
     +-------+--------+---------+------+------------+-------+

*Note regexp::, provides more information about the syntax for regular
expressions.


File: manual.info,  Node: counting-rows,  Next: multiple-tables,  Prev: pattern-matching,  Up: retrieving-data

3.3.4.8 Counting Rows
.....................

Databases are often used to answer the question, `How often does a
certain type of data occur in a table?' For example, you might want to
know how many pets you have, or how many pets each owner has, or you
might want to perform various kinds of census operations on your
animals.

Counting the total number of animals you have is the same question as
`How many rows are in the `pet' table?' because there is one record per
pet. `COUNT(*)' counts the number of rows, so the query to count your
animals looks like this:

     mysql> SELECT COUNT(*) FROM pet;
     +----------+
     | COUNT(*) |
     +----------+
     |        9 |
     +----------+

Earlier, you retrieved the names of the people who owned pets.  You can
use `COUNT()' if you want to find out how many pets each owner has:

     mysql> SELECT owner, COUNT(*) FROM pet GROUP BY owner;
     +--------+----------+
     | owner  | COUNT(*) |
     +--------+----------+
     | Benny  |        2 |
     | Diane  |        2 |
     | Gwen   |        3 |
     | Harold |        2 |
     +--------+----------+

Note the use of `GROUP BY' to group all records for each `owner'.
Without it, all you get is an error message:

     mysql> SELECT owner, COUNT(*) FROM pet;
     ERROR 1140 (42000): Mixing of GROUP columns (MIN(),MAX(),COUNT(),...)
     with no GROUP columns is illegal if there is no GROUP BY clause

`COUNT()' and `GROUP BY' are useful for characterizing your data in
various ways. The following examples show different ways to perform
animal census operations.

Number of animals per species:

     mysql> SELECT species, COUNT(*) FROM pet GROUP BY species;
     +---------+----------+
     | species | COUNT(*) |
     +---------+----------+
     | bird    |        2 |
     | cat     |        2 |
     | dog     |        3 |
     | hamster |        1 |
     | snake   |        1 |
     +---------+----------+

Number of animals per sex:

     mysql> SELECT sex, COUNT(*) FROM pet GROUP BY sex;
     +------+----------+
     | sex  | COUNT(*) |
     +------+----------+
     | NULL |        1 |
     | f    |        4 |
     | m    |        4 |
     +------+----------+

(In this output, `NULL' indicates that the sex is unknown.)

Number of animals per combination of species and sex:

     mysql> SELECT species, sex, COUNT(*) FROM pet GROUP BY species, sex;
     +---------+------+----------+
     | species | sex  | COUNT(*) |
     +---------+------+----------+
     | bird    | NULL |        1 |
     | bird    | f    |        1 |
     | cat     | f    |        1 |
     | cat     | m    |        1 |
     | dog     | f    |        1 |
     | dog     | m    |        2 |
     | hamster | f    |        1 |
     | snake   | m    |        1 |
     +---------+------+----------+

You need not retrieve an entire table when you use `COUNT()'. For
example, the previous query, when performed just on dogs and cats, looks
like this:

     mysql> SELECT species, sex, COUNT(*) FROM pet
         -> WHERE species = 'dog' OR species = 'cat'
         -> GROUP BY species, sex;
     +---------+------+----------+
     | species | sex  | COUNT(*) |
     +---------+------+----------+
     | cat     | f    |        1 |
     | cat     | m    |        1 |
     | dog     | f    |        1 |
     | dog     | m    |        2 |
     +---------+------+----------+

Or, if you wanted the number of animals per sex only for animals whose
sex is known:

     mysql> SELECT species, sex, COUNT(*) FROM pet
         -> WHERE sex IS NOT NULL
         -> GROUP BY species, sex;
     +---------+------+----------+
     | species | sex  | COUNT(*) |
     +---------+------+----------+
     | bird    | f    |        1 |
     | cat     | f    |        1 |
     | cat     | m    |        1 |
     | dog     | f    |        1 |
     | dog     | m    |        2 |
     | hamster | f    |        1 |
     | snake   | m    |        1 |
     +---------+------+----------+


File: manual.info,  Node: multiple-tables,  Prev: counting-rows,  Up: retrieving-data

3.3.4.9 Using More Than one Table
.................................

The `pet' table keeps track of which pets you have. If you want to
record other information about them, such as events in their lives like
visits to the vet or when litters are born, you need another table.
What should this table look like? It needs:

   * To contain the pet name so that you know which animal each event
     pertains to.

   * A date so that you know when the event occurred.

   * A field to describe the event.

   * An event type field, if you want to be able to categorize events.

Given these considerations, the *Note `CREATE TABLE': create-table.
statement for the `event' table might look like this:

     mysql> CREATE TABLE event (name VARCHAR(20), date DATE,
         -> type VARCHAR(15), remark VARCHAR(255));

As with the `pet' table, it is easiest to load the initial records by
creating a tab-delimited text file containing the following information.

*name*      *date*      *type*      *remark*
Fluffy      1995-05-15  litter      4 kittens, 3 female, 1
                                    male
Buffy       1993-06-23  litter      5 puppies, 2 female, 3
                                    male
Buffy       1994-06-19  litter      3 puppies, 3 female
Chirpy      1999-03-21  vet         needed beak straightened
Slim        1997-08-03  vet         broken rib
Bowser      1991-10-12  kennel      
Fang        1991-10-12  kennel      
Fang        1998-08-28  birthday    Gave him a new chew toy
Claws       1998-03-17  birthday    Gave him a new flea
                                    collar
Whistler    1998-12-09  birthday    First birthday

Load the records like this:

     mysql> LOAD DATA LOCAL INFILE 'event.txt' INTO TABLE event;

Based on what you have learned from the queries that you have run on
the `pet' table, you should be able to perform retrievals on the
records in the `event' table; the principles are the same.  But when is
the `event' table by itself insufficient to answer questions you might
ask?

Suppose that you want to find out the ages at which each pet had its
litters. We saw earlier how to calculate ages from two dates. The
litter date of the mother is in the `event' table, but to calculate her
age on that date you need her birth date, which is stored in the `pet'
table. This means the query requires both tables:

     mysql> SELECT pet.name,
         -> (YEAR(date)-YEAR(birth)) - (RIGHT(date,5)<RIGHT(birth,5)) AS age,
         -> remark
         -> FROM pet INNER JOIN event
         ->   ON pet.name = event.name
         -> WHERE event.type = 'litter';
     +--------+------+-----------------------------+
     | name   | age  | remark                      |
     +--------+------+-----------------------------+
     | Fluffy |    2 | 4 kittens, 3 female, 1 male |
     | Buffy  |    4 | 5 puppies, 2 female, 3 male |
     | Buffy  |    5 | 3 puppies, 3 female         |
     +--------+------+-----------------------------+

There are several things to note about this query:

   * The `FROM' clause joins two tables because the query needs to pull
     information from both of them.

   * When combining (joining) information from multiple tables, you
     need to specify how records in one table can be matched to records
     in the other. This is easy because they both have a `name' column.
     The query uses an `ON' clause to match up records in the two
     tables based on the `name' values.

     The query uses an `INNER JOIN' to combine the tables. An `INNER
     JOIN' allows for rows from either table to appear in the result if
     and only if both tables meet the conditions specified in the `ON'
     clause. In this example, the `ON' clause specifies that the `name'
     column in the `pet' table must match the `name' column in the
     `event' table. If a name appears in one table but not the other,
     the row will not appear in the result because the condition in the
     `ON' clause fails.

   * Because the `name' column occurs in both tables, you must be
     specific about which table you mean when referring to the column.
     This is done by prepending the table name to the column name.

You need not have two different tables to perform a join.  Sometimes it
is useful to join a table to itself, if you want to compare records in
a table to other records in that same table. For example, to find
breeding pairs among your pets, you can join the `pet' table with
itself to produce candidate pairs of males and females of like species:

     mysql> SELECT p1.name, p1.sex, p2.name, p2.sex, p1.species
         -> FROM pet AS p1 INNER JOIN pet AS p2
         ->   ON p1.species = p2.species AND p1.sex = 'f' AND p2.sex = 'm';
     +--------+------+--------+------+---------+
     | name   | sex  | name   | sex  | species |
     +--------+------+--------+------+---------+
     | Fluffy | f    | Claws  | m    | cat     |
     | Buffy  | f    | Fang   | m    | dog     |
     | Buffy  | f    | Bowser | m    | dog     |
     +--------+------+--------+------+---------+

In this query, we specify aliases for the table name to refer to the
columns and keep straight which instance of the table each column
reference is associated with.


File: manual.info,  Node: getting-information,  Next: batch-mode,  Prev: database-use,  Up: tutorial

3.4 Getting Information About Databases and Tables
==================================================

What if you forget the name of a database or table, or what the
structure of a given table is (for example, what its columns are
called)? MySQL addresses this problem through several statements that
provide information about the databases and tables it supports.

You have previously seen *Note `SHOW DATABASES': show-databases, which
lists the databases managed by the server. To find out which database
is currently selected, use the `DATABASE()' function:

     mysql> SELECT DATABASE();
     +------------+
     | DATABASE() |
     +------------+
     | menagerie  |
     +------------+

If you have not yet selected any database, the result is `NULL'.

To find out what tables the default database contains (for example,
when you are not sure about the name of a table), use this command:

     mysql> SHOW TABLES;
     +---------------------+
     | Tables_in_menagerie |
     +---------------------+
     | event               |
     | pet                 |
     +---------------------+

The name of the column in the output produced by this statement is
always `Tables_in_DB_NAME', where DB_NAME is the name of the database.
See *Note show-tables::, for more information.

If you want to find out about the structure of a table, the *Note
`DESCRIBE': describe. command is useful; it displays information about
each of a table's columns:

     mysql> DESCRIBE pet;
     +---------+-------------+------+-----+---------+-------+
     | Field   | Type        | Null | Key | Default | Extra |
     +---------+-------------+------+-----+---------+-------+
     | name    | varchar(20) | YES  |     | NULL    |       |
     | owner   | varchar(20) | YES  |     | NULL    |       |
     | species | varchar(20) | YES  |     | NULL    |       |
     | sex     | char(1)     | YES  |     | NULL    |       |
     | birth   | date        | YES  |     | NULL    |       |
     | death   | date        | YES  |     | NULL    |       |
     +---------+-------------+------+-----+---------+-------+

`Field' indicates the column name, `Type' is the data type for the
column, `NULL' indicates whether the column can contain `NULL' values,
`Key' indicates whether the column is indexed, and `Default' specifies
the column's default value. `Extra' displays special information about
columns: If a column was created with the `AUTO_INCREMENT' option, the
value will be `auto_increment' rather than empty.

`DESC' is a short form of *Note `DESCRIBE': describe. See *Note
describe::, for more information.

You can obtain the *Note `CREATE TABLE': create-table.  statement
necessary to create an existing table using the *Note `SHOW CREATE
TABLE': show-create-table. statement. See *Note show-create-table::.

If you have indexes on a table, `SHOW INDEX FROM TBL_NAME' produces
information about them. See *Note show-index::, for more about this
statement.


File: manual.info,  Node: batch-mode,  Next: examples,  Prev: getting-information,  Up: tutorial

3.5 Using `mysql' in Batch Mode
===============================

In the previous sections, you used *Note `mysql': mysql.  interactively
to enter queries and view the results. You can also run *Note `mysql':
mysql. in batch mode. To do this, put the commands you want to run in a
file, then tell *Note `mysql': mysql. to read its input from the file:

     shell> mysql < BATCH-FILE

If you are running *Note `mysql': mysql. under Windows and have some
special characters in the file that cause problems, you can do this:

     C:\> mysql -e "source BATCH-FILE"

If you need to specify connection parameters on the command line, the
command might look like this:

     shell> mysql -h HOST -u USER -p < BATCH-FILE
     Enter password: ********

When you use *Note `mysql': mysql. this way, you are creating a script
file, then executing the script.

If you want the script to continue even if some of the statements in it
produce errors, you should use the `--force' command-line option.

Why use a script? Here are a few reasons:

   * If you run a query repeatedly (say, every day or every week),
     making it a script allows you to avoid retyping it each time you
     execute it.

   * You can generate new queries from existing ones that are similar
     by copying and editing script files.

   * Batch mode can also be useful while you're developing a query,
     particularly for multiple-line commands or multiple-statement
     sequences of commands. If you make a mistake, you don't have to
     retype everything. Just edit your script to correct the error,
     then tell *Note `mysql': mysql. to execute it again.

   * If you have a query that produces a lot of output, you can run the
     output through a pager rather than watching it scroll off the top
     of your screen:

          shell> mysql < BATCH-FILE | more

   * You can catch the output in a file for further processing:

          shell> mysql < BATCH-FILE > mysql.out

   * You can distribute your script to other people so that they can
     also run the commands.

   * Some situations do not allow for interactive use, for example,
     when you run a query from a `cron' job. In this case, you must use
     batch mode.

The default output format is different (more concise) when you run
*Note `mysql': mysql. in batch mode than when you use it interactively.
For example, the output of `SELECT DISTINCT species FROM pet' looks
like this when *Note `mysql': mysql. is run interactively:

     +---------+
     | species |
     +---------+
     | bird    |
     | cat     |
     | dog     |
     | hamster |
     | snake   |
     +---------+

In batch mode, the output looks like this instead:

     species
     bird
     cat
     dog
     hamster
     snake

If you want to get the interactive output format in batch mode, use
`mysql -t'. To echo to the output the commands that are executed, use
`mysql -vvv'.

You can also use scripts from the *Note `mysql': mysql. prompt by using
the `source' command or `\.' command:

     mysql> source FILENAME;
     mysql> \. FILENAME

See *Note batch-commands::, for more information.


File: manual.info,  Node: examples,  Next: twin,  Prev: batch-mode,  Up: tutorial

3.6 Examples of Common Queries
==============================

* Menu:

* example-maximum-column::       The Maximum Value for a Column
* example-maximum-row::          The Row Holding the Maximum of a Certain Column
* example-maximum-column-group::  Maximum of Column per Group
* example-maximum-column-group-row::  The Rows Holding the Group-wise Maximum of a Certain Field
* example-user-variables::       Using User-Defined Variables
* example-foreign-keys::         Using Foreign Keys
* searching-on-two-keys::        Searching on Two Keys
* calculating-days::             Calculating Visits Per Day
* example-auto-increment::       Using `AUTO_INCREMENT'

Here are examples of how to solve some common problems with MySQL.

Some of the examples use the table `shop' to hold the price of each
article (item number) for certain traders (dealers). Supposing that
each trader has a single fixed price per article, then (`article',
`dealer') is a primary key for the records.

Start the command-line tool *Note `mysql': mysql. and select a database:

     shell> mysql YOUR-DATABASE-NAME

(In most MySQL installations, you can use the database named `test').

You can create and populate the example table with these statements:

     CREATE TABLE shop (
         article INT(4) UNSIGNED ZEROFILL DEFAULT '0000' NOT NULL,
         dealer  CHAR(20)                 DEFAULT ''     NOT NULL,
         price   DOUBLE(16,2)             DEFAULT '0.00' NOT NULL,
         PRIMARY KEY(article, dealer));
     INSERT INTO shop VALUES
         (1,'A',3.45),(1,'B',3.99),(2,'A',10.99),(3,'B',1.45),
         (3,'C',1.69),(3,'D',1.25),(4,'D',19.95);

After issuing the statements, the table should have the following
contents:

     SELECT * FROM shop;

     +---------+--------+-------+
     | article | dealer | price |
     +---------+--------+-------+
     |    0001 | A      |  3.45 |
     |    0001 | B      |  3.99 |
     |    0002 | A      | 10.99 |
     |    0003 | B      |  1.45 |
     |    0003 | C      |  1.69 |
     |    0003 | D      |  1.25 |
     |    0004 | D      | 19.95 |
     +---------+--------+-------+


File: manual.info,  Node: example-maximum-column,  Next: example-maximum-row,  Prev: examples,  Up: examples

3.6.1 The Maximum Value for a Column
------------------------------------

`What is the highest item number?'

     SELECT MAX(article) AS article FROM shop;

     +---------+
     | article |
     +---------+
     |       4 |
     +---------+


File: manual.info,  Node: example-maximum-row,  Next: example-maximum-column-group,  Prev: example-maximum-column,  Up: examples

3.6.2 The Row Holding the Maximum of a Certain Column
-----------------------------------------------------

_Task: Find the number, dealer, and price of the most expensive
article._

This is easily done with a subquery:

     SELECT article, dealer, price
     FROM   shop
     WHERE  price=(SELECT MAX(price) FROM shop);

Another solution is to sort all rows descending by price and get only
the first row using the MySQL-specific `LIMIT' clause:

     SELECT article, dealer, price
     FROM shop
     ORDER BY price DESC
     LIMIT 1;

*Note*:

If there were several most expensive articles, each with a price of
19.95, the `LIMIT' solution would show only one of them.


File: manual.info,  Node: example-maximum-column-group,  Next: example-maximum-column-group-row,  Prev: example-maximum-row,  Up: examples

3.6.3 Maximum of Column per Group
---------------------------------

_Task: Find the highest price per article._

     SELECT article, MAX(price) AS price
     FROM   shop
     GROUP BY article;

     +---------+-------+
     | article | price |
     +---------+-------+
     |    0001 |  3.99 |
     |    0002 | 10.99 |
     |    0003 |  1.69 |
     |    0004 | 19.95 |
     +---------+-------+


File: manual.info,  Node: example-maximum-column-group-row,  Next: example-user-variables,  Prev: example-maximum-column-group,  Up: examples

3.6.4 The Rows Holding the Group-wise Maximum of a Certain Field
----------------------------------------------------------------

_Task: For each article, find the dealer or dealers with the most
expensive price._

This problem can be solved with a subquery like this one:

     SELECT article, dealer, price
     FROM   shop s1
     WHERE  price=(SELECT MAX(s2.price)
                   FROM shop s2
                   WHERE s1.article = s2.article);

     +---------+--------+-------+
     | article | dealer | price |
     +---------+--------+-------+
     |    0001 | B      |  3.99 |
     |    0002 | A      | 10.99 |
     |    0003 | C      |  1.69 |
     |    0004 | D      | 19.95 |
     +---------+--------+-------+

The preceding example uses a correlated subquery, which can be
inefficient (see *Note correlated-subqueries::). Other possibilities
for solving the problem are to use a uncorrelated subquery in the
`FROM' clause or a `LEFT JOIN':

     SELECT s1.article, dealer, s1.price
     FROM shop s1
     JOIN (
       SELECT article, MAX(price) AS price
       FROM shop
       GROUP BY article) AS s2
       ON s1.article = s2.article AND s1.price = s2.price;

     SELECT s1.article, s1.dealer, s1.price
     FROM shop s1
     LEFT JOIN shop s2 ON s1.article = s2.article AND s1.price < s2.price
     WHERE s2.article IS NULL;

The `LEFT JOIN' works on the basis that when `s1.price' is at its
maximum value, there is no `s2.price' with a greater value and the `s2'
rows values will be `NULL'. See *Note join::.


File: manual.info,  Node: example-user-variables,  Next: example-foreign-keys,  Prev: example-maximum-column-group-row,  Up: examples

3.6.5 Using User-Defined Variables
----------------------------------

You can employ MySQL user variables to remember results without having
to store them in temporary variables in the client. (See *Note
user-variables::.)

For example, to find the articles with the highest and lowest price you
can do this:

     mysql> SELECT @min_price:=MIN(price),@max_price:=MAX(price) FROM shop;
     mysql> SELECT * FROM shop WHERE price=@min_price OR price=@max_price;
     +---------+--------+-------+
     | article | dealer | price |
     +---------+--------+-------+
     |    0003 | D      |  1.25 |
     |    0004 | D      | 19.95 |
     +---------+--------+-------+

*Note*:

It is also possible to store the name of a database object such as a
table or a column in a user variable and then to use this variable in
an SQL statement; however, this requires the use of a prepared
statement. See *Note sql-syntax-prepared-statements::, for more
information.


File: manual.info,  Node: example-foreign-keys,  Next: searching-on-two-keys,  Prev: example-user-variables,  Up: examples

3.6.6 Using Foreign Keys
------------------------

In MySQL, `InnoDB' tables support checking of foreign key constraints.
See *Note innodb::, and *Note ansi-diff-foreign-keys::.

A foreign key constraint is not required merely to join two tables. For
storage engines other than `InnoDB', it is possible when defining a
column to use a `REFERENCES TBL_NAME(COL_NAME)' clause, which has no
actual effect, and _serves only as a memo or comment to you that the
column which you are currently defining is intended to refer to a
column in another table_. It is extremely important to realize when
using this syntax that:

   * MySQL does not perform any sort of `CHECK' to make sure that
     COL_NAME actually exists in TBL_NAME (or even that TBL_NAME itself
     exists).

   * MySQL does not perform any sort of action on TBL_NAME such as
     deleting rows in response to actions taken on rows in the table
     which you are defining; in other words, this syntax induces no `ON
     DELETE' or `ON UPDATE' behavior whatsoever. (Although you can
     write an `ON DELETE' or `ON UPDATE' clause as part of the
     `REFERENCES' clause, it is also ignored.)

   * This syntax creates a _column_; it does *not* create any sort of
     index or key.

You can use a column so created as a join column, as shown here:

     CREATE TABLE person (
         id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
         name CHAR(60) NOT NULL,
         PRIMARY KEY (id)
     );

     CREATE TABLE shirt (
         id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
         style ENUM('t-shirt', 'polo', 'dress') NOT NULL,
         color ENUM('red', 'blue', 'orange', 'white', 'black') NOT NULL,
         owner SMALLINT UNSIGNED NOT NULL REFERENCES person(id),
         PRIMARY KEY (id)
     );

     INSERT INTO person VALUES (NULL, 'Antonio Paz');

     SELECT @last := LAST_INSERT_ID();

     INSERT INTO shirt VALUES
     (NULL, 'polo', 'blue', @last),
     (NULL, 'dress', 'white', @last),
     (NULL, 't-shirt', 'blue', @last);

     INSERT INTO person VALUES (NULL, 'Lilliana Angelovska');

     SELECT @last := LAST_INSERT_ID();

     INSERT INTO shirt VALUES
     (NULL, 'dress', 'orange', @last),
     (NULL, 'polo', 'red', @last),
     (NULL, 'dress', 'blue', @last),
     (NULL, 't-shirt', 'white', @last);

     SELECT * FROM person;
     +----+---------------------+
     | id | name                |
     +----+---------------------+
     |  1 | Antonio Paz         |
     |  2 | Lilliana Angelovska |
     +----+---------------------+

     SELECT * FROM shirt;
     +----+---------+--------+-------+
     | id | style   | color  | owner |
     +----+---------+--------+-------+
     |  1 | polo    | blue   |     1 |
     |  2 | dress   | white  |     1 |
     |  3 | t-shirt | blue   |     1 |
     |  4 | dress   | orange |     2 |
     |  5 | polo    | red    |     2 |
     |  6 | dress   | blue   |     2 |
     |  7 | t-shirt | white  |     2 |
     +----+---------+--------+-------+

     SELECT s.* FROM person p INNER JOIN shirt s
        ON s.owner = p.id
      WHERE p.name LIKE 'Lilliana%'
        AND s.color <> 'white';

     +----+-------+--------+-------+
     | id | style | color  | owner |
     +----+-------+--------+-------+
     |  4 | dress | orange |     2 |
     |  5 | polo  | red    |     2 |
     |  6 | dress | blue   |     2 |
     +----+-------+--------+-------+

When used in this fashion, the `REFERENCES' clause is not displayed in
the output of *Note `SHOW CREATE TABLE': show-create-table. or *Note
`DESCRIBE': describe.:

     SHOW CREATE TABLE shirt\G
     *************************** 1. row ***************************
     Table: shirt
     Create Table: CREATE TABLE `shirt` (
     `id` smallint(5) unsigned NOT NULL auto_increment,
     `style` enum('t-shirt','polo','dress') NOT NULL,
     `color` enum('red','blue','orange','white','black') NOT NULL,
     `owner` smallint(5) unsigned NOT NULL,
     PRIMARY KEY  (`id`)
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1

The use of `REFERENCES' in this way as a comment or `reminder' in a
column definition works with `MyISAM' tables.


File: manual.info,  Node: searching-on-two-keys,  Next: calculating-days,  Prev: example-foreign-keys,  Up: examples

3.6.7 Searching on Two Keys
---------------------------

An `OR' using a single key is well optimized, as is the handling of
`AND'.

The one tricky case is that of searching on two different keys combined
with `OR':

     SELECT field1_index, field2_index FROM test_table
     WHERE field1_index = '1' OR  field2_index = '1'

This case is optimized. See *Note index-merge-optimization::.

You can also solve the problem efficiently by using a *Note `UNION':
union. that combines the output of two separate *Note `SELECT': select.
statements.  See *Note union::.

Each *Note `SELECT': select. searches only one key and can be optimized:

     SELECT field1_index, field2_index
         FROM test_table WHERE field1_index = '1'
     UNION
     SELECT field1_index, field2_index
         FROM test_table WHERE field2_index = '1';


File: manual.info,  Node: calculating-days,  Next: example-auto-increment,  Prev: searching-on-two-keys,  Up: examples

3.6.8 Calculating Visits Per Day
--------------------------------

The following example shows how you can use the bit group functions to
calculate the number of days per month a user has visited a Web page.

     CREATE TABLE t1 (year YEAR(4), month INT(2) UNSIGNED ZEROFILL,
                  day INT(2) UNSIGNED ZEROFILL);
     INSERT INTO t1 VALUES(2000,1,1),(2000,1,20),(2000,1,30),(2000,2,2),
                 (2000,2,23),(2000,2,23);

The example table contains year-month-day values representing visits by
users to the page. To determine how many different days in each month
these visits occur, use this query:

     SELECT year,month,BIT_COUNT(BIT_OR(1<<day)) AS days FROM t1
            GROUP BY year,month;

Which returns:

     +------+-------+------+
     | year | month | days |
     +------+-------+------+
     | 2000 |    01 |    3 |
     | 2000 |    02 |    2 |
     +------+-------+------+

The query calculates how many different days appear in the table for
each year/month combination, with automatic removal of duplicate
entries.


File: manual.info,  Node: example-auto-increment,  Prev: calculating-days,  Up: examples

3.6.9 Using `AUTO_INCREMENT'
----------------------------

The `AUTO_INCREMENT' attribute can be used to generate a unique
identity for new rows:

     CREATE TABLE animals (
          id MEDIUMINT NOT NULL AUTO_INCREMENT,
          name CHAR(30) NOT NULL,
          PRIMARY KEY (id)
      );

     INSERT INTO animals (name) VALUES
         ('dog'),('cat'),('penguin'),
         ('lax'),('whale'),('ostrich');

     SELECT * FROM animals;

Which returns:

     +----+---------+
     | id | name    |
     +----+---------+
     |  1 | dog     |
     |  2 | cat     |
     |  3 | penguin |
     |  4 | lax     |
     |  5 | whale   |
     |  6 | ostrich |
     +----+---------+

You can retrieve the most recent `AUTO_INCREMENT' value with the
`LAST_INSERT_ID()' SQL function or the *Note `mysql_insert_id()':
mysql-insert-id. C API function. These functions are
connection-specific, so their return values are not affected by another
connection which is also performing inserts.

*Note*:

For a multiple-row insert, `LAST_INSERT_ID()' and *Note
`mysql_insert_id()': mysql-insert-id. actually return the
`AUTO_INCREMENT' key from the _first_ of the inserted rows. This allows
multiple-row inserts to be reproduced correctly on other servers in a
replication setup.

For `MyISAM' tables you can specify `AUTO_INCREMENT' on a secondary
column in a multiple-column index. In this case, the generated value
for the `AUTO_INCREMENT' column is calculated as
`MAX(AUTO_INCREMENT_COLUMN) + 1 WHERE prefix=GIVEN-PREFIX'. This is
useful when you want to put data into ordered groups.

     CREATE TABLE animals (
         grp ENUM('fish','mammal','bird') NOT NULL,
         id MEDIUMINT NOT NULL AUTO_INCREMENT,
         name CHAR(30) NOT NULL,
         PRIMARY KEY (grp,id)
     );

     INSERT INTO animals (grp,name) VALUES
         ('mammal','dog'),('mammal','cat'),
         ('bird','penguin'),('fish','lax'),('mammal','whale'),
         ('bird','ostrich');

     SELECT * FROM animals ORDER BY grp,id;

Which returns:

     +--------+----+---------+
     | grp    | id | name    |
     +--------+----+---------+
     | fish   |  1 | lax     |
     | mammal |  1 | dog     |
     | mammal |  2 | cat     |
     | mammal |  3 | whale   |
     | bird   |  1 | penguin |
     | bird   |  2 | ostrich |
     +--------+----+---------+

Note that in this case (when the `AUTO_INCREMENT' column is part of a
multiple-column index), `AUTO_INCREMENT' values are reused if you
delete the row with the biggest `AUTO_INCREMENT' value in any group.
This happens even for `MyISAM' tables, for which `AUTO_INCREMENT'
values normally are not reused.

If the `AUTO_INCREMENT' column is part of multiple indexes, MySQL will
generate sequence values using the index that begins with the
`AUTO_INCREMENT' column, if there is one. For example, if the `animals'
table contained indexes `PRIMARY KEY (grp, id)' and `INDEX (id)', MySQL
would ignore the `PRIMARY KEY' for generating sequence values. As a
result, the table would contain a single sequence, not a sequence per
`grp' value.

To start with an `AUTO_INCREMENT' value other than 1, you can set that
value with *Note `CREATE TABLE': create-table. or *Note `ALTER TABLE':
alter-table, like this:

     mysql> ALTER TABLE tbl AUTO_INCREMENT = 100;

More information about `AUTO_INCREMENT' is available here:

   * How to assign the `AUTO_INCREMENT' attribute to a column: *Note
     create-table::, and *Note alter-table::.

   * How `AUTO_INCREMENT' behaves depending on the SQL mode: *Note
     server-sql-mode::.

   * Find the row that contains the most recent AUTO_INCREMENT value:
     *Note comparison-operators::.

   * Set the `AUTO_INCREMENT' value to be used: *Note
     server-session-variables::.

   * `AUTO_INCREMENT' and replication: *Note replication-features::.

   * Server-system variables related to `AUTO_INCREMENT'
     (`auto_increment_increment' and `auto_increment_offset') that can
     be used for replication: *Note server-system-variables::.


File: manual.info,  Node: twin,  Next: apache,  Prev: examples,  Up: tutorial

3.7 Queries from the Twin Project
=================================

* Menu:

* twin-pool::                    Find All Non-distributed Twins
* twin-event::                   Show a Table of Twin Pair Status

At the places the early MySQL was developed (Analytikerna and Lentus),
the founders did systems and field work for a big research project.
This project was a collaboration between the Institute of Environmental
Medicine at Karolinska Institutet Stockholm and the Section on Clinical
Research in Aging and Psychology at the University of Southern
California.

The project involved lots of data collection from all twins in Sweden
older than 65 Years (see
`http://ki.se/ki/jsp/polopoly.jsp?d=9610&l=en').

Large parts of the project were administered with a Web interface
written using Perl and MySQL.


File: manual.info,  Node: twin-pool,  Next: twin-event,  Prev: twin,  Up: twin

3.7.1 Find All Non-distributed Twins
------------------------------------

The following query was used to determine what twins should be studied
further after a initial screening. The time for this was around MySQL
3.19 in 1997.

     SELECT
         CONCAT(p1.id, p1.tvab) + 0 AS tvid,
         CONCAT(p1.christian_name, ' ', p1.surname) AS Name,
         p1.postal_code AS Code,
         p1.city AS City,
         pg.abrev AS Area,
         IF(td.participation = 'Aborted', 'A', ' ') AS A,
         p1.dead AS dead1,
         l.event AS event1,
         td.suspect AS tsuspect1,
         id.suspect AS isuspect1,
         td.severe AS tsevere1,
         id.severe AS isevere1,
         p2.dead AS dead2,
         l2.event AS event2,
         h2.nurse AS nurse2,
         h2.doctor AS doctor2,
         td2.suspect AS tsuspect2,
         id2.suspect AS isuspect2,
         td2.severe AS tsevere2,
         id2.severe AS isevere2,
         l.finish_date
     FROM
         twin_project AS tp
         /* For Twin 1 */
         LEFT JOIN twin_data AS td ON tp.id = td.id
                   AND tp.tvab = td.tvab
         LEFT JOIN informant_data AS id ON tp.id = id.id
                   AND tp.tvab = id.tvab
         LEFT JOIN harmony AS h ON tp.id = h.id
                   AND tp.tvab = h.tvab
         LEFT JOIN lentus AS l ON tp.id = l.id
                   AND tp.tvab = l.tvab
         /* For Twin 2 */
         LEFT JOIN twin_data AS td2 ON p2.id = td2.id
                   AND p2.tvab = td2.tvab
         LEFT JOIN informant_data AS id2 ON p2.id = id2.id
                   AND p2.tvab = id2.tvab
         LEFT JOIN harmony AS h2 ON p2.id = h2.id
                   AND p2.tvab = h2.tvab
         LEFT JOIN lentus AS l2 ON p2.id = l2.id
                   AND p2.tvab = l2.tvab,
         person_data AS p1,
         person_data AS p2,
         postal_groups AS pg
     WHERE
         /* p1 gets main twin and p2 gets his/her twin. */
         /* ptvab is a field inverted from tvab */
         p1.id = tp.id AND p1.tvab = tp.tvab AND
         p2.id = p1.id AND p2.ptvab = p1.tvab AND
         /* Just the screening survey */
         tp.survey_no = 5 AND
         /* Skip if partner died before 65 but allow emigration (dead=9) */
         (p2.dead = 0 OR p2.dead = 9 OR
          (p2.dead = 1 AND
           (p2.death_date = 0 OR
            (((TO_DAYS(p2.death_date) - TO_DAYS(p2.birthday)) / 365)
             >= 65))))
         AND
         (
         /* Twin is suspect */
         (td.future_contact = 'Yes' AND td.suspect = 2) OR
         /* Twin is suspect - Informant is Blessed */
         (td.future_contact = 'Yes' AND td.suspect = 1
                                    AND id.suspect = 1) OR
         /* No twin - Informant is Blessed */
         (ISNULL(td.suspect) AND id.suspect = 1
                             AND id.future_contact = 'Yes') OR
         /* Twin broken off - Informant is Blessed */
         (td.participation = 'Aborted'
          AND id.suspect = 1 AND id.future_contact = 'Yes') OR
         /* Twin broken off - No inform - Have partner */
         (td.participation = 'Aborted' AND ISNULL(id.suspect)
                                       AND p2.dead = 0))
         AND
         l.event = 'Finished'
         /* Get at area code */
         AND SUBSTRING(p1.postal_code, 1, 2) = pg.code
         /* Not already distributed */
         AND (h.nurse IS NULL OR h.nurse=00 OR h.doctor=00)
         /* Has not refused or been aborted */
         AND NOT (h.status = 'Refused' OR h.status = 'Aborted'
         OR h.status = 'Died' OR h.status = 'Other')
     ORDER BY
         tvid;

Some explanations:

   * `CONCAT(p1.id, p1.tvab) + 0 AS tvid'

     We want to sort on the concatenated `id' and `tvab' in numerical
     order. Adding `0' to the result causes MySQL to treat the result
     as a number.

   * column `id'

     This identifies a pair of twins. It is an index in all tables.

   * column `tvab'

     This identifies a twin in a pair. It has a value of `1' or `2'.

   * column `ptvab'

     This is an inverse of `tvab'. When `tvab' is `1' this is `2', and
     vice versa. It exists to save typing and to make it easier for
     MySQL to optimize the query.

This query demonstrates, among other things, how to do lookups on a
table from the same table with a join (`p1' and `p2'). In the example,
this is used to check whether a twin's partner died before the age of
65. If so, the row is not returned.

All of the above exist in all tables with twin-related information. We
have an index on both `id, tvab' (all tables), and `id, ptvab'
(`person_data') to make queries faster.

When we did this work, our production machine was a 200MHz UltraSPARC,
and on that old hardware this query returned about 150-200 rows in less
than one second. The main table had 70k Rows.


File: manual.info,  Node: twin-event,  Prev: twin-pool,  Up: twin

3.7.2 Show a Table of Twin Pair Status
--------------------------------------

Each twin has a status code called `event'. The query shown here is
used to select all twin pairs combined by event. This indicates in how
many pairs both twins are finished, in how many pairs one twin is
finished and the other refused, and so on.

     SELECT
             t1.event,
             t2.event,
             COUNT(*)
     FROM
             lentus AS t1,
             lentus AS t2,
             twin_project AS tp
     WHERE
             /* We are looking at one pair at a time */
             t1.id = tp.id
             AND t1.tvab=tp.tvab
             AND t1.id = t2.id
             /* Just the screening survey */
             AND tp.survey_no = 5
             /* This makes each pair only appear once */
             AND t1.tvab='1' AND t2.tvab='2'
     GROUP BY
             t1.event, t2.event;


File: manual.info,  Node: apache,  Prev: twin,  Up: tutorial

3.8 Using MySQL with Apache
===========================

There are programs that let you authenticate your users from a MySQL
database and also let you write your log files into a MySQL table.

You can change the Apache logging format to be easily readable by MySQL
by putting the following into the Apache configuration file:

     LogFormat \
             "\"%h\",%{%Y%m%d%H%M%S}t,%>s,\"%b\",\"%{Content-Type}o\",  \
             \"%U\",\"%{Referer}i\",\"%{User-Agent}i\""

To load a log file in that format into MySQL, you can use a statement
something like this:

     LOAD DATA INFILE '/LOCAL/ACCESS_LOG' INTO TABLE TBL_NAME
     FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' ESCAPED BY '\\'

The named table should be created to have columns that correspond to
those that the `LogFormat' line writes to the log file.


File: manual.info,  Node: programs,  Next: server-administration,  Prev: tutorial,  Up: Top

4 MySQL Programs
****************

* Menu:

* programs-overview::            Overview of MySQL Programs
* programs-using::               Using MySQL Programs
* programs-server::              MySQL Server and Server-Startup Programs
* programs-installation::        MySQL Installation-Related Programs
* programs-client::              MySQL Client Programs
* programs-admin-utils::         MySQL Administrative and Utility Programs
* programs-development::         MySQL Program Development Utilities
* programs-miscellaneous::       Miscellaneous Programs

This chapter provides a brief overview of the command-line programs
provided by MySQL AB. It also discusses the general syntax for
specifying options when you run these programs. Most programs have
options that are specific to their own operation, but the option syntax
is similar for all of them. Finally, the chapter provides more detailed
descriptions of individual programs, including which options they
recognize.


File: manual.info,  Node: programs-overview,  Next: programs-using,  Prev: programs,  Up: programs

4.1 Overview of MySQL Programs
==============================

There are many different programs in a MySQL installation. This section
provides a brief overview of them. Later sections provide a more
detailed description of each one. Each program's description indicates
its invocation syntax and the options that it supports.

Most MySQL distributions include all of these programs, except for
those programs that are platform-specific. (For example, the server
startup scripts are not used on Windows.) The exception is that RPM
distributions are more specialized. There is one RPM for the server,
another for client programs, and so forth. If you appear to be missing
one or more programs, see *Note installing::, for information on types
of distributions and what they contain. It may be that you have a
distribution that does not include all programs and you need to install
an additional package.

Each MySQL program takes many different options. Most programs provide
a `--help' option that you can use to get a description of the
program's different options. For example, try *Note `mysql --help':
mysql.

You can override default option values for MySQL programs by specifying
options on the command line or in an option file. See *Note
programs-using::, for general information on invoking programs and
specifying program options.

The MySQL server, *Note `mysqld': mysqld, is the main program that does
most of the work in a MySQL installation. The server is accompanied by
several related scripts that assist you in starting and stopping the
server:

   * *Note `mysqld': mysqld.

     The SQL daemon (that is, the MySQL server). To use client
     programs, *Note `mysqld': mysqld. must be running, because clients
     gain access to databases by connecting to the server.  See *Note
     mysqld::.

   * *Note `mysqld_safe': mysqld-safe.

     A server startup script. *Note `mysqld_safe': mysqld-safe.
     attempts to start *Note `mysqld': mysqld. See *Note mysqld-safe::.

   * *Note `mysql.server': mysql-server.

     A server startup script. This script is used on systems that use
     System V-style run directories containing scripts that start
     system services for particular run levels. It invokes *Note
     `mysqld_safe': mysqld-safe. to start the MySQL server. See *Note
     mysql-server::.

   * *Note `mysqld_multi': mysqld-multi.

     A server startup script that can start or stop multiple servers
     installed on the system. See *Note mysqld-multi::.

Several programs perform setup operations during MySQL installation or
upgrading:

   * *Note `comp_err': comp-err.

     This program is used during the MySQL build/installation process.
     It compiles error message files from the error source files. See
     *Note comp-err::.

   * `make_binary_distribution'

     This program makes a binary release of a compiled MySQL. This
     could be sent by FTP to `/pub/mysql/upload/' on `ftp.mysql.com'
     for the convenience of other MySQL users.

   * *Note `make_win_bin_dist': make-win-bin-dist.

     This program is used on Windows. It packages a MySQL distribution
     for installation after the source distribution has been built. See
     *Note make-win-bin-dist::.

   * *Note `mysql_install_db': mysql-install-db.

     This script creates the MySQL database and initializes the grant
     tables with default privileges. It is usually executed only once,
     when first installing MySQL on a system. See *Note
     mysql-install-db::, *Note unix-post-installation::, and *Note
     mysql-install-db::.

   * *Note `mysql_secure_installation': mysql-secure-installation.

     This program enables you to improve the security of your MySQL
     installation. SQL. See *Note mysql-secure-installation::.

   * *Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql.

     This program loads the time zone tables in the `mysql' database
     using the contents of the host system _zoneinfo_ database (the set
     of files describing time zones). SQL. See *Note
     mysql-tzinfo-to-sql::.

   * *Note `mysql_upgrade': mysql-upgrade.

     This program is used after a MySQL upgrade operation. It checks
     tables for incompatibilities and repairs them if necessary, and
     updates the grant tables with any changes that have been made in
     newer versions of MySQL. See *Note mysql-upgrade::.

MySQL client programs that connect to the MySQL server:

   * *Note `mysql': mysql.

     The command-line tool for interactively entering SQL statements or
     executing them from a file in batch mode. See *Note mysql::.

   * *Note `mysqladmin': mysqladmin.

     A client that performs administrative operations, such as creating
     or dropping databases, reloading the grant tables, flushing tables
     to disk, and reopening log files.  *Note `mysqladmin': mysqladmin.
     can also be used to retrieve version, process, and status
     information from the server. See *Note mysqladmin::.

   * *Note `mysqlcheck': mysqlcheck.

     A table-maintenance client that checks, repairs, analyzes, and
     optimizes tables. See *Note mysqlcheck::.

   * *Note `mysqldump': mysqldump.

     A client that dumps a MySQL database into a file as SQL, text, or
     XML. See *Note mysqldump::.

   * *Note `mysqlimport': mysqlimport.

     A client that imports text files into their respective tables
     using *Note `LOAD DATA INFILE': load-data. See *Note mysqlimport::.

   * *Note `mysqlshow': mysqlshow.

     A client that displays information about databases, tables,
     columns, and indexes. See *Note mysqlshow::.

   * *Note `mysqlslap': mysqlslap.

     A client that is designed to emulate client load for a MySQL
     server and report the timing of each stage. It works as if
     multiple clients are accessing the server. See *Note mysqlslap::.

MySQL administrative and utility programs:

   * *Note `innochecksum': innochecksum.

     An offline `InnoDB' offline file checksum utility. See *Note
     innochecksum::.

   * *Note `myisam_ftdump': myisam-ftdump.

     A utility that displays information about full-text indexes in
     `MyISAM' tables. See *Note myisam-ftdump::.

   * *Note `myisamchk': myisamchk.

     A utility to describe, check, optimize, and repair `MyISAM'
     tables. See *Note myisamchk::.

   * *Note `myisamlog': myisamlog, `isamlog'

     A utility that processes the contents of a `MyISAM' log file. See
     *Note myisamlog::.

   * *Note `myisampack': myisampack.

     A utility that compresses `MyISAM' tables to produce smaller
     read-only tables. See *Note myisampack::.

   * *Note `mysqlaccess': mysqlaccess.

     A script that checks the access privileges for a host name, user
     name, and database combination. See *Note mysqlaccess::.

   * *Note `mysqlbinlog': mysqlbinlog.

     A utility for reading statements from a binary log. The log of
     executed statements contained in the binary log files can be used
     to help recover from a crash. See *Note mysqlbinlog::.

   * *Note `mysqldumpslow': mysqldumpslow.

     A utility to read and summarize the contents of a slow query log.
     See *Note mysqldumpslow::.

   * *Note `mysqlhotcopy': mysqlhotcopy.

     A utility that quickly makes backups of `MyISAM' tables while the
     server is running.  See *Note mysqlhotcopy::.

   * *Note `mysql_convert_table_format': mysql-convert-table-format.

     A utility that converts tables in a database to use a given
     storage engine. See *Note mysql-convert-table-format::.

   * *Note `mysql_find_rows': mysql-find-rows.

     A utility that reads files containing SQL statements (such as
     update logs) and extracts statements that match a given regular
     expression. See *Note mysql-find-rows::.

   * *Note `mysql_fix_extensions': mysql-fix-extensions.

     A utility that converts the extensions for `MyISAM' table files to
     lowercase. This can be useful after transferring the files from a
     system with case-insensitive file names to a system with
     case-sensitive file names. See *Note mysql-fix-extensions::.

   * *Note `mysql_setpermission': mysql-setpermission.

     A utility for interactively setting permissions in the MySQL grant
     tables. See *Note mysql-setpermission::.

   * *Note `mysql_waitpid': mysql-waitpid.

     A utility that kills the process with a given process ID. See
     *Note mysql-waitpid::.

   * *Note `mysql_zap': mysql-zap.

     A utility that kills processes that match a pattern. See *Note
     mysql-zap::.

MySQL program-development utilities:

   * *Note `msql2mysql': msql2mysql.

     A shell script that converts `mSQL' programs to MySQL. It doesn't
     handle every case, but it gives a good start when converting. See
     *Note msql2mysql::.

   * *Note `mysql_config': mysql-config.

     A shell script that produces the option values needed when
     compiling MySQL programs. See *Note mysql-config::.

   * *Note `my_print_defaults': my-print-defaults.

     A utility that shows which options are present in option groups of
     option files. See *Note my-print-defaults::.

   * *Note `resolve_stack_dump': resolve-stack-dump.

     A utility program that resolves a numeric stack trace dump to
     symbols. See *Note resolve-stack-dump::.

Miscellaneous utilities:

   * *Note `perror': perror.

     A utility that displays the meaning of system or MySQL error
     codes. See *Note perror::.

   * *Note `replace': replace-utility.

     A utility program that performs string replacement in the input
     text. See *Note replace-utility::.

   * *Note `resolveip': resolveip.

     A utility program that resolves a host name to an IP address or
     vice versa. See *Note resolveip::.

MySQL AB also provides several GUI tools for administering and
otherwise working with MySQL Server:

   * MySQL Administrator: This tool is used for administering MySQL
     servers, databases, tables, and user accounts.

   * MySQL Query Browser: This graphical tool is provided by MySQL AB
     for creating, executing, and optimizing queries on MySQL databases.

   * MySQL Migration Toolkit: This tool helps you migrate schemas and
     data from other relational database management systems for use
     with MySQL.

These GUI programs are available at `http://dev.mysql.com/downloads/'.
Each has its own manual that you can access at
`http://dev.mysql.com/doc/'.

MySQL client programs that communicate with the server using the MySQL
client/server library use the following environment variables.

`MYSQL_UNIX_PORT'  The default Unix socket file; used for connections to
                   `localhost'
`MYSQL_TCP_PORT'   The default port number; used for TCP/IP connections
`MYSQL_PWD'        The default password
`MYSQL_DEBUG'      Debug trace options when debugging
`TMPDIR'           The directory where temporary tables and files are
                   created

For a full list of environment variables used by MySQL programs, see
*Note environment-variables::.

Use of `MYSQL_PWD' is insecure. See *Note password-security-user::.


File: manual.info,  Node: programs-using,  Next: programs-server,  Prev: programs-overview,  Up: programs

4.2 Using MySQL Programs
========================

* Menu:

* invoking-programs::            Invoking MySQL Programs
* connecting::                   Connecting to the MySQL Server
* program-options::              Specifying Program Options
* setting-environment-variables::  Setting Environment Variables


File: manual.info,  Node: invoking-programs,  Next: connecting,  Prev: programs-using,  Up: programs-using

4.2.1 Invoking MySQL Programs
-----------------------------

To invoke a MySQL program from the command line (that is, from your
shell or command prompt), enter the program name followed by any
options or other arguments needed to instruct the program what you want
it to do. The following commands show some sample program invocations.
``shell>'' represents the prompt for your command interpreter; it is
not part of what you type. The particular prompt you see depends on your
command interpreter. Typical prompts are `$' for `sh' or `bash', `%'
for `csh' or `tcsh', and `C:\>' for the Windows `command.com' or
`cmd.exe' command interpreters.

     shell> mysql --user=root test
     shell> mysqladmin extended-status variables
     shell> mysqlshow --help
     shell> mysqldump -u root personnel

Arguments that begin with a single or double dash (``-'', ``--'')
specify program options.  Options typically indicate the type of
connection a program should make to the server or affect its
operational mode. Option syntax is described in *Note program-options::.

Non-option arguments (arguments with no leading dash) provide
additional information to the program. For example, the *Note `mysql':
mysql. program interprets the first non-option argument as a database
name, so the command `mysql --user=root test' indicates that you want
to use the `test' database.

Later sections that describe individual programs indicate which options
a program supports and describe the meaning of any additional
non-option arguments.

Some options are common to a number of programs. The most frequently
used of these are the `--host' (or `-h'), `--user' (or `-u'), and
`--password' (or `-p') options that specify connection parameters.
They indicate the host where the MySQL server is running, and the user
name and password of your MySQL account. All MySQL client programs
understand these options; they allow you to specify which server to
connect to and the account to use on that server. Other connection
options are `--port' (or `-P') to specify a TCP/IP port number and
`--socket' (or `-S') to specify a Unix socket file on Unix (or named
pipe name on Windows). For more information on options that specify
connection options, see *Note connecting::.

You may find it necessary to invoke MySQL programs using the path name
to the `bin' directory in which they are installed. This is likely to
be the case if you get a `program not found' error whenever you attempt
to run a MySQL program from any directory other than the `bin'
directory. To make it more convenient to use MySQL, you can add the
path name of the `bin' directory to your `PATH' environment variable
setting. That enables you to run a program by typing only its name, not
its entire path name. For example, if *Note `mysql': mysql. is
installed in `/usr/local/mysql/bin', you can run the program by
invoking it as *Note `mysql': mysql, and it is not necessary to invoke
it as `/usr/local/mysql/bin/mysql'.

Consult the documentation for your command interpreter for instructions
on setting your `PATH' variable. The syntax for setting environment
variables is interpreter-specific.  (Some information is given in *Note
setting-environment-variables::.) After modifying your `PATH' setting,
open a new console window on Windows or log in again on Unix so that
the setting goes into effect.


File: manual.info,  Node: connecting,  Next: program-options,  Prev: invoking-programs,  Up: programs-using

4.2.2 Connecting to the MySQL Server
------------------------------------

For a client program to be able to connect to the MySQL server, it must
use the proper connection parameters, such as the name of the host
where the server is running and the user name and password of your
MySQL account. Each connection parameter has a default value, but you
can override them as necessary using program options specified either
on the command line or in an option file.

The examples here use the *Note `mysql': mysql. client program, but the
principles apply to other clients such as *Note `mysqldump': mysqldump,
*Note `mysqladmin': mysqladmin, or *Note `mysqlshow': mysqlshow.

This command invokes *Note `mysql': mysql. without specifying any
connection parameters explicitly:

     shell> mysql

Because there are no parameter options, the default values apply:

   * The default host name is `localhost'. On Unix, this has a special
     meaning, as described later.

   * The default user name is `ODBC' on Windows or your Unix login name
     on Unix.

   * No password is sent if neither `-p' nor `--password' is given.

   * For *Note `mysql': mysql, the first non-option argument is taken
     as the name of the default database. If there is no such option,
     *Note `mysql': mysql. does not select a default database.

To specify the host name and user name explicitly, as well as a
password, supply appropriate options on the command line:

     shell> mysql --host=localhost --user=myname --password=mypass mydb
     shell> mysql -h localhost -u myname -pmypass mydb

For password options, the password value is optional:

   * If you use a `-p' or `--password' option and specify the password
     value, there must be _no space_ between `-p' or `--password=' and
     the password following it.

   * If you use a `-p' or `--password' option but do not specify the
     password value, the client program prompts you to enter the
     password. The password is not displayed as you enter it. This is
     more secure than giving the password on the command line. Other
     users on your system may be able to see a password specified on
     the command line by executing a command such as `ps auxw'. See
     *Note password-security-user::.

As just mentioned, including the password value on the command line can
be a security risk. To avoid this problem, specify the `--password' or
`-p' option without any following password value:

     shell> mysql --host=localhost --user=myname --password mydb
     shell> mysql -h localhost -u myname -p mydb

When the password option has no password value, the client program
prints a prompt and waits for you to enter the password. (In these
examples, `mydb' is _not_ interpreted as a password because it is
separated from the preceding password option by a space.)

On some systems, the library routine that MySQL uses to prompt for a
password automatically limits the password to eight characters.  That
is a problem with the system library, not with MySQL.  Internally,
MySQL does not have any limit for the length of the password. To work
around the problem, change your MySQL password to a value that is eight
or fewer characters long, or put your password in an option file.

On Unix, MySQL programs treat the host name `localhost' specially, in a
way that is likely different from what you expect compared to other
network-based programs. For connections to `localhost', MySQL programs
attempt to connect to the local server by using a Unix socket file.
This occurs even if a `--port' or `-P' option is given to specify a
port number. To ensure that the client makes a TCP/IP connection to the
local server, use `--host' or `-h' to specify a host name value of
`127.0.0.1', or the IP address or name of the local server. You can
also specify the connection protocol explicitly, even for `localhost',
by using the `--protocol=TCP' option. For example:

     shell> mysql --host=127.0.0.1
     shell> mysql --protocol=TCP

The `--protocol' option enables you to establish a particular type of
connection even when the other options would normally default to some
other protocol.

On Windows, you can force a MySQL client to use a named-pipe connection
by specifying the `--pipe' or `--protocol=PIPE' option, or by
specifying `.' (period) as the host name. If named-pipe connections are
not enabled, an error occurs. Use the `--socket' option to specify the
name of the pipe if you do not want to use the default pipe name.

Connections to remote servers always use TCP/IP. This command connects
to the server running on `remote.example.com' using the default port
number (3306):

     shell> mysql --host=remote.example.com

To specify a port number explicitly, use the `--port' or `-P' option:

     shell> mysql --host=remote.example.com --port=13306

You can specify a port number for connections to a local server, too.
However, as indicated previously, connections to `localhost' on Unix
will use a socket file by default. You will need to force a TCP/IP
connection as already described or any option that specifies a port
number will be ignored.

For this command, the program uses a socket file on Unix and the
`--port' option is ignored:

     shell> mysql --port=13306 --host=localhost

To cause the port number to be used, invoke the program in either of
these ways:

     shell> mysql --port=13306 --host=127.0.0.1
     shell> mysql --port=13306 --protocol=TCP

The following list summarizes the options that can be used to control
how client programs connect to the server:

   *  `--host=HOST_NAME', `-h HOST_NAME'

     The host where the server is running. The default value is
     `localhost'.

   *  `--password[=PASS_VAL]', `-p[PASS_VAL]'

     The password of the MySQL account. As described earlier, the
     password value is optional, but if given, there must be _no space_
     between `-p' or `--password=' and the password following it. The
     default is to send no password.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server. The server must be
     started with the `--enable-named-pipe' option to enable named-pipe
     connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The port number to use for the connection, for connections made
     via TCP/IP. The default port number is 3306.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     This option explicitly specifies a protocol to use for connecting
     to the server. It is useful when the other connection parameters
     normally would cause a protocol to be used other than the one you
     want. For example, connections on Unix to `localhost' are made via
     a Unix socket file by default:

          shell> mysql --host=localhost

     To force a TCP/IP connection to be used instead, specify a
     `--protocol' option:

          shell> mysql --host=localhost --protocol=TCP

     The following table shows the allowable `--protocol' option values
     and indicates the platforms on which each value may be used. The
     values are not case sensitive.

     _`--protocol' _Connection Protocol_              _Allowable
     Value_                                           Operating Systems_
     `TCP'         TCP/IP connection to local or      All
                   remote server                      
     `SOCKET'      Unix socket file connection to     Unix only
                   local server                       
     `PIPE'        Named-pipe connection to local     Windows only
                   server                             
     `MEMORY'      Shared-memory connection to local  Windows only
                   server                             

   *  `--shared-memory-base-name=NAME'

     On Windows, the shared-memory name to use, for connections made
     via shared memory to a local server. The default value is `MYSQL'.
     The shared-memory name is case sensitive.

     The server must be started with the `--shared-memory' option to
     enable shared-memory connections.

   *  `--socket=FILE_NAME', `-S FILE_NAME'

     On Unix, the name of the Unix socket file to use, for connections
     made via a named pipe to a local server. The default Unix socket
     file name is `/tmp/mysql.sock'.

     On Windows, the name of the named pipe to use, for connections to
     a local server. The default Windows pipe name is `MySQL'. The pipe
     name is not case sensitive.

     The server must be started with the `--enable-named-pipe' option to
     enable named-pipe connections.

   * `--ssl*'

     Options that begin with `--ssl' are used for establishing a secure
     connection to the server via SSL, if the server is configured with
     SSL support. For details, see *Note ssl-options::.

   *  `--user=USER_NAME', `-u USER_NAME'

     The user name of the MySQL account you want to use. The default
     user name is `ODBC' on Windows or your Unix login name on Unix.

It is possible to specify different default values to be used when you
make a connection so that you need not enter them on the command line
each time you invoke a client program. This can be done in a couple of
ways:

   * You can specify connection parameters in the `[client]' section of
     an option file. The relevant section of the file might look like
     this:

          [client]
          host=HOST_NAME
          user=USER_NAME
          password=YOUR_PASS

     *Note option-files::, discusses option files further.

   * You can specify some connection parameters using environment
     variables. The host can be specified for *Note `mysql': mysql.
     using `MYSQL_HOST'.  The MySQL user name can be specified using
     `USER' (this is for Windows and NetWare only). The password can be
     specified using `MYSQL_PWD', although this is insecure; see *Note
     password-security-user::. For a list of variables, see *Note
     environment-variables::.


File: manual.info,  Node: program-options,  Next: setting-environment-variables,  Prev: connecting,  Up: programs-using

4.2.3 Specifying Program Options
--------------------------------

* Menu:

* command-line-options::         Using Options on the Command Line
* option-files::                 Using Option Files
* program-variables::            Using Options to Set Program Variables
* option-defaults-equals::       Option Defaults, Options Expecting Values, and the `=' Sign

There are several ways to specify options for MySQL programs:

   * List the options on the command line following the program name.
     This is most common for options that apply to a specific
     invocation of the program.

   * List the options in an option file that the program reads when it
     starts. This is common for options that you want the program to
     use each time it runs.

   * List the options in environment variables (see *Note
     setting-environment-variables::). This method is useful for
     options that you want to apply each time the program runs. In
     practice, option files are used more commonly for this purpose,
     but *Note multiple-unix-servers::, discusses one situation in
     which environment variables can be very helpful. It describes a
     handy technique that uses such variables to specify the TCP/IP
     port number and Unix socket file for the server and for client
     programs.

MySQL programs determine which options are given first by examining
environment variables, then by reading option files, and then by
checking the command line. This means that environment variables have
the lowest precedence and command-line options the highest.

Because options are processed in order, if an option is specified
multiple times, the last occurrence takes precedence. The following
command causes *Note `mysql': mysql. to connect to the server running
on `localhost':

     shell> mysql -h example.com -h localhost

If conflicting or related options are given, later options take
precedence over earlier options. The following command runs *Note
`mysql': mysql. in `no column names' mode:

     shell> mysql --column-names --skip-column-names

An option can be specified by writing it in full or as any unambiguous
prefix. For example, the `--compress' option can be given to *Note
`mysqldump': mysqldump. as `--compr', but not as `--comp' because the
latter is ambiguous:

     shell> mysqldump --comp
     mysqldump: ambiguous option '--comp' (compatible, compress)

Be aware that the use of option prefixes can cause problems in the
event that new options are implemented for a program. A prefix that is
unambiguous now might become ambiguous in the future.

You can take advantage of the way that MySQL programs process options
by specifying default values for a program's options in an option file.
That enables you to avoid typing them each time you run the program,
but also allows you to override the defaults if necessary by using
command-line options.


File: manual.info,  Node: command-line-options,  Next: option-files,  Prev: program-options,  Up: program-options

4.2.3.1 Using Options on the Command Line
.........................................

* Menu:

* option-modifiers::             Program Option Modifiers

Program options specified on the command line follow these rules:

   * Options are given after the command name.

   * An option argument begins with one dash or two dashes, depending
     on whether it is a short form or long form of the option name.
     Many options have both short and long forms.  For example, `-?'
     and `--help' are the short and long forms of the option that
     instructs a MySQL program to display its help message.

   * Option names are case sensitive. `-v' and `-V' are both legal and
     have different meanings. (They are the corresponding short forms
     of the `--verbose' and `--version' options.)

   * Some options take a value following the option name. For example,
     `-h localhost' or `--host=localhost' indicate the MySQL server
     host to a client program. The option value tells the program the
     name of the host where the MySQL server is running.

   * For a long option that takes a value, separate the option name and
     the value by an ``='' sign. For a short option that takes a value,
     the option value can immediately follow the option letter, or
     there can be a space between: `-hlocalhost' and `-h localhost' are
     equivalent. An exception to this rule is the option for specifying
     your MySQL password. This option can be given in long form as
     `--password=PASS_VAL' or as `--password'. In the latter case (with
     no password value given), the program prompts you for the
     password. The password option also may be given in short form as
     `-pPASS_VAL' or as `-p'. However, for the short form, if the
     password value is given, it must follow the option letter with _no
     intervening space_. The reason for this is that if a space follows
     the option letter, the program has no way to tell whether a
     following argument is supposed to be the password value or some
     other kind of argument. Consequently, the following two commands
     have two completely different meanings:

          shell> mysql -ptest
          shell> mysql -p test

     The first command instructs *Note `mysql': mysql. to use a
     password value of `test', but specifies no default database. The
     second instructs *Note `mysql': mysql. to prompt for the password
     value and to use `test' as the default database.

   * Within option names, dash (``-'') and underscore (``_'') may be
     used interchangeably. For example, `--skip-grant-tables' and
     `--skip_grant_tables' are equivalent. (However, the leading dashes
     cannot be given as underscores.)

Another option that may occasionally be useful with *Note `mysql':
mysql. is the `--execute' or `-e' option, which can be used to pass SQL
statements to the server.  When this option is used, *Note `mysql':
mysql. executes the statements and exits. The statements must be
enclosed by quotation marks. For example, you can use the following
command to obtain a list of user accounts:

     shell> mysql -u root -p --execute="SELECT User, Host FROM user" mysql
     Enter password: ******
     +------+-----------+
     | User | Host      |
     +------+-----------+
     |      | gigan     |
     | root | gigan     |
     |      | localhost |
     | jon  | localhost |
     | root | localhost |
     +------+-----------+
     shell>

Note that the long form (`--execute') is followed by an equals sign
(`=').

If you wish to use quoted values within a statement, you will either
need to escape the inner quotes, or use a different type of quotes
within the statement from those used to quote the statement itself. The
capabilities of your command processor dictate your choices for whether
you can use single or double quotation marks and the syntax for
escaping quote characters.  For example, if your command processor
supports quoting with single or double quotes, you can double quotes
around the statement, and single quotes for any quoted values within the
statement.

In the preceding example, the name of the `mysql' database was passed
as a separate argument. However, the same statement could have been
executed using this command, which specifies no default database:

     mysql> mysql -u root -p --execute="SELECT User, Host FROM mysql.user"

Multiple SQL statements may be passed on the command line, separated by
semicolons:

     shell> mysql -u root -p -e "SELECT VERSION();SELECT NOW()"
     Enter password: ******
     +-----------------+
     | VERSION()       |
     +-----------------+
     | 5.1.5-alpha-log |
     +-----------------+
     +---------------------+
     | NOW()               |
     +---------------------+
     | 2006-01-05 21:19:04 |
     +---------------------+


File: manual.info,  Node: option-modifiers,  Prev: command-line-options,  Up: command-line-options

4.2.3.2 Program Option Modifiers
................................

Some options control behavior that can be turned on or off.  For
example, the *Note `mysql': mysql. client supports a `--column-names'
option that determines whether or not to display a row of column names
at the beginning of query results. By default, this option is enabled.
However, you may want to disable it in some instances, such as when
sending the output of *Note `mysql': mysql. into another program that
expects to see only data and not an initial header line.

To disable column names, you can specify the option using any of these
forms:

     --disable-column-names
     --skip-column-names
     --column-names=0

The `--disable' and `--skip' prefixes and the `=0' suffix all have the
same effect: They turn the option off.

The `enabled' form of the option may be specified in any of these ways:

     --column-names
     --enable-column-names
     --column-names=1

If an option is prefixed by `--loose', a program does not exit with an
error if it does not recognize the option, but instead issues only a
warning:

     shell> mysql --loose-no-such-option
     mysql: WARNING: unknown option '--no-such-option'

The `--loose' prefix can be useful when you run programs from multiple
installations of MySQL on the same machine and list options in an
option file, An option that may not be recognized by all versions of a
program can be given using the `--loose' prefix (or `loose' in an
option file). Versions of the program that recognize the option process
it normally, and versions that do not recognize it issue a warning and
ignore it.

*Note `mysqld': mysqld. enables a limit to be placed on how large
client programs can set dynamic system variables. To do this, use a
`--maximum' prefix with the variable name. For example,
`--maximum-query_cache_size=4M' prevents any client from making the
query cache size larger than 4MB.


File: manual.info,  Node: option-files,  Next: program-variables,  Prev: command-line-options,  Up: program-options

4.2.3.3 Using Option Files
..........................

* Menu:

* option-file-options::          Command-Line Options that Affect Option-File Handling
* option-files-preconfigured::   Preconfigured Option Files

Most MySQL programs can read startup options from option files (also
sometimes called configuration files). Option files provide a
convenient way to specify commonly used options so that they need not
be entered on the command line each time you run a program. For the
MySQL server, MySQL provides a number of *Note preconfigured option
files: option-files-preconfigured.

To determine whether a program reads option files, invoke it with the
`--help' option. (For *Note `mysqld': mysqld, use `--verbose' and
`--help'.) If the program reads option files, the help message
indicates which files it looks for and which option groups it
recognizes.

On Windows, MySQL programs read startup options from the following
files.

*File Name*            *Purpose*
`WINDIR\my.ini',       Global options
`WINDIR\my.cnf'        
`C:\my.ini',           Global options
`C:\my.cnf'            
`INSTALLDIR\my.ini',   Global options
`INSTALLDIR\my.cnf'    
`defaults-extra-file'  The file specified with
                       `--defaults-extra-file=PATH', if any

WINDIR represents the location of your Windows directory. This is
commonly `C:\WINDOWS'. You can determine its exact location from the
value of the `WINDIR' environment variable using the following command:

     C:\> echo %WINDIR%

INSTALLDIR represents the MySQL installation directory. This is
typically `C:\PROGRAMDIR\MySQL\MySQL 6.0 Server' where PROGRAMDIR
represents the programs directory (usually `Program Files' on
English-language versions of Windows), when MySQL 6.0 has been
installed using the installation and configuration wizards. See The
Location of the my.ini File
(http://dev.mysql.com/doc/refman/4.1/en/windows-config-wizard.html#mysql-config-wizard-file-location).

On Unix, MySQL programs read startup options from the following files.

*File Name*            *Purpose*
`/etc/my.cnf'          Global options
`/etc/mysql/my.cnf'    Global options
`SYSCONFDIR/my.cnf'    Global options
`$MYSQL_HOME/my.cnf'   Server-specific options
`defaults-extra-file'  The file specified with
                       `--defaults-extra-file=PATH', if any
`~/.my.cnf'            User-specific options

SYSCONFDIR represents the directory specified with the `--sysconfdir'
option to `configure' when MySQL was built. By default, this is the
`etc' directory located under the compiled-in installation directory.

`MYSQL_HOME' is an environment variable containing the path to the
directory in which the server-specific `my.cnf' file resides.

If `MYSQL_HOME' is not set and you start the server using the *Note
`mysqld_safe': mysqld-safe. program, *Note `mysqld_safe': mysqld-safe.
attempts to set `MYSQL_HOME' as follows:

   * Let BASEDIR and DATADIR represent the path names of the MySQL base
     directory and data directory, respectively.

   * If there is a `my.cnf' file in DATADIR but not in BASEDIR, *Note
     `mysqld_safe': mysqld-safe. sets `MYSQL_HOME' to DATADIR.

   * Otherwise, if `MYSQL_HOME' is not set and there is no `my.cnf'
     file in DATADIR, *Note `mysqld_safe': mysqld-safe. sets
     `MYSQL_HOME' to BASEDIR.

In MySQL 6.0, use of DATADIR as the location for `my.cnf' is deprecated.

Typically, DATADIR is `/usr/local/mysql/data' for a binary installation
or `/usr/local/var' for a source installation. Note that this is the
data directory location that was specified at configuration time, not
the one specified with the `--datadir' option when *Note `mysqld':
mysqld. starts. Use of `--datadir' at runtime has no effect on where
the server looks for option files, because it looks for them before
processing any options.

MySQL looks for option files in the order just described and reads any
that exist. If an option file that you want to use does not exist,
create it with a plain text editor.

If multiple instances of a given option are found, the last instance
takes precedence. There is one exception: For *Note `mysqld': mysqld,
the _first_ instance of the `--user' option is used as a security
precaution, to prevent a user specified in an option file from being
overridden on the command line.

*Note*:

On Unix platforms, MySQL ignores configuration files that are
world-writable. This is intentional as a security measure.

Any long option that may be given on the command line when running a
MySQL program can be given in an option file as well.  To get the list
of available options for a program, run it with the `--help' option.

The syntax for specifying options in an option file is similar to
command-line syntax, except that you omit the leading two dashes and
you specify only one option per line. For example, `--quick' and
`--host=localhost' on the command line should be specified as `quick'
and `host=localhost' on separate lines in an option file. To specify an
option of the form `--loose-OPT_NAME' in an option file, write it as
`loose-OPT_NAME'.

Empty lines in option files are ignored. Non-empty lines can take any
of the following forms:

   * `#COMMENT', `;COMMENT'

     Comment lines start with ``#'' or ``;''. A ``#'' comment can start
     in the middle of a line as well.

   * `[GROUP]'

     GROUP is the name of the program or group for which you want to
     set options. After a group line, any option-setting lines apply to
     the named group until the end of the option file or another group
     line is given.

   * `OPT_NAME'

     This is equivalent to `--OPT_NAME' on the command line.

   * `OPT_NAME=VALUE'

     This is equivalent to `--OPT_NAME=VALUE' on the command line. In
     an option file, you can have spaces around the ``='' character,
     something that is not true on the command line. You can enclose
     the value within single quotes or double quotes, which is useful
     if the value contains a ``#'' comment character or whitespace.

For options that take a numeric value, the value can be given with a
suffix of `K', `M', or `G' (either uppercase or lowercase) to indicate
a multiplier of 1024, 1024^2 or 1024^3. For example, the following
command tells *Note `mysqladmin': mysqladmin. to ping the server 1024
times, sleeping 10 seconds between each ping:

     mysql> mysqladmin --count=1K --sleep=10 ping

Leading and trailing blanks are automatically deleted from option names
and values. You may use the escape sequences ``\b'', ``\t'', ``\n'',
``\r'', ``\\'', and ``\s'' in option values to represent the backspace,
tab, newline, carriage return, backslash, and space characters.

Because the ``\\'' escape sequence represents a single backslash, you
must write each ``\'' as ``\\''. Alternatively, you can specify the
value using ``/'' rather than ``\'' as the path name separator.

If an option group name is the same as a program name, options in the
group apply specifically to that program. For example, the `[mysqld]'
and `[mysql]' groups apply to the *Note `mysqld': mysqld. server and the
*Note `mysql': mysql. client program, respectively.

The `[client]' option group is read by all client programs (but _not_ by
*Note `mysqld': mysqld.). This allows you to specify options that apply
to all clients. For example, `[client]' is the perfect group to use to
specify the password that you use to connect to the server. (But make
sure that the option file is readable and writable only by yourself, so
that other people cannot find out your password.)  Be sure not to put
an option in the `[client]' group unless it is recognized by _all_
client programs that you use. Programs that do not understand the
option quit after displaying an error message if you try to run them.

Here is a typical global option file:

     [client]
     port=3306
     socket=/tmp/mysql.sock

     [mysqld]
     port=3306
     socket=/tmp/mysql.sock
     key_buffer_size=16M
     max_allowed_packet=8M

     [mysqldump]
     quick

The preceding option file uses `VAR_NAME=VALUE' syntax for the lines
that set the `key_buffer_size' and `max_allowed_packet' variables.

Here is a typical user option file:

     [client]
     # The following password will be sent to all standard MySQL clients
     password="my_password"

     [mysql]
     no-auto-rehash
     connect_timeout=2

     [mysqlhotcopy]
     interactive-timeout

If you want to create option groups that should be read by *Note
`mysqld': mysqld. servers from a specific MySQL release series only,
you can do this by using groups with names of `[mysqld-5.1]',
`[mysqld-6.0]', and so forth. The following group indicates that the
`--new' option should be used only by MySQL servers with 6.0.x version
numbers:

     [mysqld-6.0]
     new

It is possible to use `!include' directives in option files to include
other option files and `!includedir' to search specific directories for
option files. For example, to include the `/home/mydir/myopt.cnf' file,
use the following directive:

     !include /home/mydir/myopt.cnf

To search the `/home/mydir' directory and read option files found
there, use this directive:

     !includedir /home/mydir

There is no guarantee about the order in which the option files in the
directory will be read.

*Note*:

Currently, any files to be found and included using the `!includedir'
directive on Unix operating systems _must_ have file names ending in
`.cnf'. On Windows, this directive checks for files with the `.ini' or
`.cnf' extension.

Write the contents of an included option file like any other option
file. That is, it should contain groups of options, each preceded by a
`[GROUP]' line that indicates the program to which the options apply.

While an included file is being processed, only those options in groups
that the current program is looking for are used. Other groups are
ignored. Suppose that a `my.cnf' file contains this line:

     !include /home/mydir/myopt.cnf

And suppose that `/home/mydir/myopt.cnf' looks like this:

     [mysqladmin]
     force

     [mysqld]
     key_buffer_size=16M

If `my.cnf' is processed by *Note `mysqld': mysqld, only the `[mysqld]'
group in `/home/mydir/myopt.cnf' is used. If the file is processed by
*Note `mysqladmin': mysqladmin, only the `[mysqldamin]' group is used.
If the file is processed by any other program, no options in
`/home/mydir/myopt.cnf' are used.

The `!includedir' directive is processed similarly except that all
option files in the named directory are read.


File: manual.info,  Node: option-file-options,  Next: option-files-preconfigured,  Prev: option-files,  Up: option-files

4.2.3.4 Command-Line Options that Affect Option-File Handling
.............................................................

Most MySQL programs that support option files handle the following
options. They affect option-file handling, so they must be given on the
command line and not in an option file.  To work properly, each of
these options must immediately follow the command name, with the
exception that `--print-defaults' may be used immediately after
`--defaults-file' or `--defaults-extra-file'. Also, when specifying
file names, you should avoid the use of the ``~'' shell metacharacter
because it might not be interpreted as you expect.

   *  `--defaults-extra-file=FILE_NAME'

     Read this option file after the global option file but (on Unix)
     before the user option file.  FILE_NAME is the full path name to
     the file. If the file does not exist or is otherwise inaccessible,
     the program will exit with an error.

   *  `--defaults-file=FILE_NAME'

     Use only the given option file.  FILE_NAME is the full path name
     to the file. If the file does not exist or is otherwise
     inaccessible, the program will exit with an error.

   *  `--defaults-group-suffix=STR'

     If this option is given, the program reads not only its usual
     option groups, but also groups with the usual names and a suffix
     of STR. For example, the *Note `mysql': mysql. client normally
     reads the `[client]' and `[mysql]' groups. If the
     `--defaults-group-suffix=_other' option is given, *Note `mysql':
     mysql. also reads the `[client_other]' and `[mysql_other]' groups.

   *  `--no-defaults'

     Do not read any option files. If a program does not start because
     it is reading unknown options from an option file, `--no-defaults'
     can be used to prevent the program from reading them.

   *  `--print-defaults'

     Print the program name and all options that it gets from option
     files.


File: manual.info,  Node: option-files-preconfigured,  Prev: option-file-options,  Up: option-files

4.2.3.5 Preconfigured Option Files
..................................

MySQL provides a number of preconfigured option files that can be used
as a basis for tuning the MySQL server. Look for files such as
`my-small.cnf', `my-medium.cnf', `my-large.cnf', and `my-huge.cnf',
which are sample option files for small, medium, large, and very large
systems. On Windows, the extension is `.ini' rather than `.cnf'
extension.

*Note*:

On Windows, the `.cnf' or `.ini' option file extension might not be
displayed.

For a binary distribution, look for the files in or under your
installation directory. If you have a source distribution, look in the
`support-files' directory. You can rename a copy of a sample file and
place it in the appropriate location for use as a base configuration
file.  Regarding names and appropriate location, see the general
information provided in *Note option-files::.


File: manual.info,  Node: program-variables,  Next: option-defaults-equals,  Prev: option-files,  Up: program-options

4.2.3.6 Using Options to Set Program Variables
..............................................

Many MySQL programs have internal variables that can be set at runtime
using the *Note `SET': set-option.  statement. See *Note set-option::,
and *Note using-system-variables::.

Most of these program variables also can be set at server startup by
using the same syntax that applies to specifying program options. For
example, *Note `mysql': mysql. has a `max_allowed_packet' variable that
controls the maximum size of its communication buffer. To set the
`max_allowed_packet' variable for *Note `mysql': mysql. to a value of
16MB, use either of the following commands:

     shell> mysql --max_allowed_packet=16777216
     shell> mysql --max_allowed_packet=16M

The first command specifies the value in bytes. The second specifies
the value in megabytes. For variables that take a numeric value, the
value can be given with a suffix of `K', `M', or `G' (either uppercase
or lowercase) to indicate a multiplier of 1024, 1024^2 or 1024^3. (For
example, when used to set `max_allowed_packet', the suffixes indicate
units of kilobytes, megabytes, or gigabytes.)

In an option file, variable settings are given without the leading
dashes:

     [mysql]
     max_allowed_packet=16777216

Or:

     [mysql]
     max_allowed_packet=16M

If you like, underscores in a variable name can be specified as dashes.
The following option groups are equivalent. Both set the size of the
server's key buffer to 512MB:

     [mysqld]
     key_buffer_size=512M

     [mysqld]
     key-buffer-size=512M

A variable can be specified by writing it in full or as any unambiguous
prefix. For example, the `max_allowed_packet' variable can be set for
*Note `mysql': mysql. as `--max_a', but not as `--max' because the
latter is ambiguous:

     shell> mysql --max=1000000
     mysql: ambiguous option '--max=1000000' (max_allowed_packet, max_join_size)

Be aware that the use of variable prefixes can cause problems in the
event that new variables are implemented for a program. A prefix that
is unambiguous now might become ambiguous in the future.

Suffixes for specifying a value multiplier can be used when setting a
variable at server startup, but not to set the value with *Note `SET':
set-option.  at runtime. On the other hand, with *Note `SET':
set-option. you can assign a variable's value using an expression,
which is not true when you set a variable at server startup. For
example, the first of the following lines is legal at server startup,
but the second is not:

     shell> mysql --max_allowed_packet=16M
     shell> mysql --max_allowed_packet=16*1024*1024

Conversely, the second of the following lines is legal at runtime, but
the first is not:

     mysql> SET GLOBAL max_allowed_packet=16M;
     mysql> SET GLOBAL max_allowed_packet=16*1024*1024;

*Note*:

Before MySQL 4.0.2, the only syntax for setting program variables was
`--set-variable=OPTION=VALUE' (or `set-variable=OPTION=VALUE' in option
files). Underscores cannot be given as dashes, and the variable name
must be specified in full. This syntax still is recognized, but is now
deprecated.


File: manual.info,  Node: option-defaults-equals,  Prev: program-variables,  Up: program-options

4.2.3.7 Option Defaults, Options Expecting Values, and the `=' Sign
...................................................................

By convention, long forms of options that assign a value are written
with an equals (`=') sign, like this:

     shell> mysql --host=tonfisk --user=jon

For options that require a value (that is, not having a default value),
the equals sign is not required, and so the following is also valid:

     shell> mysql --host tonfisk --user jon

In both cases, the *Note `mysql': mysql. client attempts to connect to
a MySQL server running on the host named `tonfisk' using an account
with the user name `jon'.

Due to this behavior, problems can occasionally arise when no value is
provided for an option that expects one. Consider the following
example, where a user connects to a MySQL server running on host
`tonfisk' as user `jon':

     shell> mysql --host 85.224.35.45 --user jon
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 3
     Server version: 6.0.12 Source distribution

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql> SELECT CURRENT_USER();
     +----------------+
     | CURRENT_USER() |
     +----------------+
     | jon@%          |
     +----------------+
     1 row in set (0.00 sec)

Omitting the required value for one of these option yields an error,
such as the one shown here:

     shell> mysql --host 85.224.35.45 --user
     `mysql: option '--user' requires an argument'

In this case, *Note `mysql': mysql. was unable to find a value
following the `--user' option because nothing came after it on the
command line.  However, if you omit the value for an option that is
_not_ the last option to be used, you obtain a different error that you
may not be expecting:

     shell> mysql --host --user jon
     `ERROR 2005 (HY000): Unknown MySQL server host '--user' (1)'

Because *Note `mysql': mysql. assumes that any string following
`--host' on the command line is a host name, `--host' `--user' is
interpreted as `--host=--user', and the client attempts to connect to a
MySQL server running on a host named `--user'.

Options having default values always require an equals sign when
assigning a value; failing to do so causes an error. For example, the
MySQL server `--log-error' option has the default value `HOST_NAME.err',
where HOST_NAME is the name of the host on which MySQL is running.
Assume that you are running MySQL on a computer whose host name is
`tonfisk', and consider the following invocation of *Note
`mysqld_safe': mysqld-safe.:

     shell> mysqld_safe &
     [1] 11699
     shell> 080112 12:53:40 mysqld_safe Logging to '/usr/local/mysql/var/tonfisk.err'.
     080112 12:53:40 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var
     shell>

After shutting down the server, restart it as follows:

     shell> mysqld_safe --log-error &
     [1] 11699
     shell> 080112 12:53:40 mysqld_safe Logging to '/usr/local/mysql/var/tonfisk.err'.
     080112 12:53:40 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var
     shell>

The result is the same, since `--log-error' is not followed by anything
else on the command line, and it supplies its own default value. (The
`&' character tells the operating system to run MySQL in the
background; it is ignored by MySQL itself.) Now suppose that you wish
to log errors to a file named `my-errors.err'. You might try starting
the server with `--log-error my-errors', but this does not have the
intended effect, as shown here:

     shell> mysqld_safe --log-error my-errors &
     [1] 31357
     shell> 080111 22:53:31 mysqld_safe Logging to '/usr/local/mysql/var/tonfisk.err'.
     080111 22:53:32 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var
     080111 22:53:34 mysqld_safe mysqld from pid file /usr/local/mysql/var/tonfisk.pid ended

     [1]+  Done                    ./mysqld_safe --log-error my-errors

The server attempted to start using `/usr/local/mysql/var/tonfisk.err'
as the error log, but then shut down. Examining the last few lines of
this file shows the reason:

     shell> tail /usr/local/mysql/var/tonfisk.err
     080111 22:53:32  InnoDB: Started; log sequence number 0 46409
     `/usr/local/mysql/libexec/mysqld: Too many arguments (first extra is 'my-errors').
     Use --verbose --help to get a list of available options'
     080111 22:53:32 `[ERROR] Aborting'

     080111 22:53:32  InnoDB: Starting shutdown...
     080111 22:53:34  InnoDB: Shutdown completed; log sequence number 0 46409
     080111 22:53:34 [Note] /usr/local/mysql/libexec/mysqld: Shutdown complete

     080111 22:53:34 mysqld_safe mysqld from pid file /usr/local/mysql/var/tonfisk.pid ended

Because the `--log-error' option supplies a default value, you must use
an equals sign to assign a different value to it, as shown here:

     shell> mysqld_safe --log-error=my-errors &
     [1] 31437
     shell> 080111 22:54:15 mysqld_safe Logging to '/usr/local/mysql/var/my-errors.err'.
     080111 22:54:15 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var

     shell>

Now the server has been started successfully, and is logging errors to
the file `/usr/local/mysql/var/my-errors.err'.

Similar issues can arise when specifying option values in option files.
For example, consider a `my.cnf' file that contains the following:

     [mysql]

     host
     user

When the *Note `mysql': mysql. client reads this file, these entries
are parsed as `--host' `--user' or `--host=--user', with the result
shown here:

     shell> mysql
     `ERROR 2005 (HY000): Unknown MySQL server host '--user' (1)'

However, in option files, an equals sign is not assumed. Suppose the
`my.cnf' file is as shown here:

     [mysql]

     user jon

Trying to start *Note `mysql': mysql. in this case causes a different
error:

     shell> mysql
     `mysql: unknown option '--user jon''

A similar error would occur if you were to write `host tonfisk' in the
option file rather than `host=tonfisk'. Instead, you must use the
equals sign:

     [mysql]

     user=jon

     shell> mysql
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 5
     Server version: 6.0.12 Source distribution

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql> SELECT USER();
     +---------------+
     | USER()        |
     +---------------+
     | jon@localhost |
     +---------------+
     1 row in set (0.00 sec)

This is not the same behavior as with the command line, where the
equals sign is not required:

     shell> mysql --user jon --host tonfisk
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 6
     Server version: 6.0.12 Source distribution

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql> SELECT USER();
     +---------------+
     | USER()        |
     +---------------+
     | jon@tonfisk   |
     +---------------+
     1 row in set (0.00 sec)


File: manual.info,  Node: setting-environment-variables,  Prev: program-options,  Up: programs-using

4.2.4 Setting Environment Variables
-----------------------------------

Environment variables can be set at the command prompt to affect the
current invocation of your command processor, or set permanently to
affect future invocations. To set a variable permanently, you can set
it in a startup file or by using the interface provided by your system
for this purpose. Consult the documentation for your command
interpreter for specific details.  *Note environment-variables::, lists
all environment variables that affect MySQL program operation.

To specify a value for an environment variable, use the syntax
appropriate for your command processor. For example, on Windows or
NetWare, you can set the `USER' variable to specify your MySQL account
name. To do so, use this syntax:

     SET USER=YOUR_NAME

The syntax on Unix depends on your shell. Suppose that you want to
specify the TCP/IP port number using the `MYSQL_TCP_PORT' variable.
Typical syntax (such as for `sh', `bash', `zsh', and so on) is as
follows:

     MYSQL_TCP_PORT=3306
     export MYSQL_TCP_PORT

The first command sets the variable, and the `export' command exports
the variable to the shell environment so that its value becomes
accessible to MySQL and other processes.

For `csh' and `tcsh', use `setenv' to make the shell variable available
to the environment:

     setenv MYSQL_TCP_PORT 3306

The commands to set environment variables can be executed at your
command prompt to take effect immediately, but the settings persist
only until you log out. To have the settings take effect each time you
log in, use the interface provided by your system or place the
appropriate command or commands in a startup file that your command
interpreter reads each time it starts.

On Windows, you can set environment variables using the System Control
Panel (under Advanced).

On Unix, typical shell startup files are `.bashrc' or `.bash_profile'
for `bash', or `.tcshrc' for `tcsh'.

Suppose that your MySQL programs are installed in
`/usr/local/mysql/bin' and that you want to make it easy to invoke
these programs. To do this, set the value of the `PATH' environment
variable to include that directory. For example, if your shell is
`bash', add the following line to your `.bashrc' file:

     PATH=${PATH}:/usr/local/mysql/bin

`bash' uses different startup files for login and non-login shells, so
you might want to add the setting to `.bashrc' for login shells and to
`.bash_profile' for non-login shells to make sure that `PATH' is set
regardless.

If your shell is `tcsh', add the following line to your `.tcshrc' file:

     setenv PATH ${PATH}:/usr/local/mysql/bin

If the appropriate startup file does not exist in your home directory,
create it with a text editor.

After modifying your `PATH' setting, open a new console window on
Windows or log in again on Unix so that the setting goes into effect.


File: manual.info,  Node: programs-server,  Next: programs-installation,  Prev: programs-using,  Up: programs

4.3 MySQL Server and Server-Startup Programs
============================================

* Menu:

* mysqld::                       `mysqld' --- The MySQL Server
* mysqld-safe::                  `mysqld_safe' --- MySQL Server Startup Script
* mysql-server::                 `mysql.server' --- MySQL Server Startup Script
* mysqld-multi::                 `mysqld_multi' --- Manage Multiple MySQL Servers

This section describes *Note `mysqld': mysqld, the MySQL server, and
several programs that are used to start the server.


File: manual.info,  Node: mysqld,  Next: mysqld-safe,  Prev: programs-server,  Up: programs-server

4.3.1 `mysqld' -- The MySQL Server
----------------------------------

*Note `mysqld': mysqld, also known as MySQL Server, is the main program
that does most of the work in a MySQL installation.  MySQL Server
manages access to the MySQL data directory that contains databases and
tables. The data directory is also the default location for other
information such as log files and status files.

When MySQL server starts, it listens for network connections from
client programs and manages access to databases on behalf of those
clients.

The *Note `mysqld': mysqld. program has many options that can be
specified at startup. For a complete list of options, run this command:

     shell> mysqld --verbose --help

MySQL Server also has a set of system variables that affect its
operation as it runs. System variables can be set at server startup,
and many of them can be changed at runtime to effect dynamic server
reconfiguration. MySQL Server also has a set of status variables that
provide information about its operation.  You can monitor these status
variables to access runtime performance characteristics.

For a full description of MySQL Server command options, system
variables, and status variables, see *Note mysqld-server::. For
information about installing MySQL and setting up the initial
configuration, see *Note installing::.


File: manual.info,  Node: mysqld-safe,  Next: mysql-server,  Prev: mysqld,  Up: programs-server

4.3.2 `mysqld_safe' -- MySQL Server Startup Script
--------------------------------------------------

*Note `mysqld_safe': mysqld-safe. is the recommended way to start a
*Note `mysqld': mysqld. server on Unix and NetWare.  *Note
`mysqld_safe': mysqld-safe. adds some safety features such as
restarting the server when an error occurs and logging runtime
information to an error log file. Descriptions of error logging and
NetWare-specific behaviors are given later in this section.

*Note `mysqld_safe': mysqld-safe. tries to start an executable named
*Note `mysqld': mysqld. To override the default behavior and specify
explicitly the name of the server you want to run, specify a `--mysqld'
or `--mysqld-version' option to *Note `mysqld_safe': mysqld-safe. You
can also use `--ledir' to indicate the directory where *Note
`mysqld_safe': mysqld-safe. should look for the server.

Many of the options to *Note `mysqld_safe': mysqld-safe. are the same
as the options to *Note `mysqld': mysqld. See *Note server-options::.

All options specified to *Note `mysqld_safe': mysqld-safe. on the
command line are passed to *Note `mysqld': mysqld. If you want to use
any options that are specific to *Note `mysqld_safe': mysqld-safe. and
that *Note `mysqld': mysqld. doesn't support, do not specify them on
the command line. Instead, list them in the `[mysqld_safe]' group of an
option file. See *Note option-files::.

*Note `mysqld_safe': mysqld-safe. reads all options from the
`[mysqld]', `[server]', and `[mysqld_safe]' sections in option files.
For example, if you specify a `[mysqld]' section like this, *Note
`mysqld_safe': mysqld-safe. will find and use the `--log-error' option:

     [mysqld]
     log-error=error.log

For backward compatibility, *Note `mysqld_safe': mysqld-safe. also
reads `[safe_mysqld]' sections, although you should rename such
sections to `[mysqld_safe]' in MySQL 6.0 installations.

*`mysqld_safe' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-autoclose  autoclose   On NetWare, mysqld_safe provides a           
                        screen presence                              
-basedir=pathbasedir     The path to the MySQL installation           
                        directory                                    
-core-file-size=sizecore-file-sizeThe size of the core file that               
                        mysqld should be able to create              
-datadir=pathdatadir     The path to the data directory               
-defaults-extra-file=pathdefaults-extra-fileThe name of an option file to be             
                        read in addition to the usual                
                        option files                                 
-defaults-file=file_namedefaults-fileThe name of an option file to be             
                        read instead of the usual option             
                        files                                        
-help                   Display a help message and exit              
-ledir=path ledir       Use this option to indicate the              
                        path name to the directory where             
                        the server is located                        
-log-error=file_namelog-error   Write the error log to the given             
                        file                                         
-mysqld=prog_namemysqld      The name of the server program (in           
                        the ledir directory) that you  want          
                        to start                                     
-mysqld-version=suffixmysqld-versionThis option is similar to the                
                        -mysqld option, but you specify              
                        only the suffix for the server               
                        program name                                 
-nice=prioritynice        Use the nice program to set the              
                        server's scheduling priority to              
                        the given value                              
-no-defaultsno-defaults Do not read any option files                 
-open-files-limit=countopen-files-limitThe number of files that mysqld              
                        should be able to open                       
-pid-file   pid-file    The path name of the process ID file         
-port=numberport        The port number that the server              
                        should use when listening for                
                        TCP/IP connections                           
-skip-kill-mysqldskip-kill-mysqldDo not try to kill stray mysqld              
                        processes                                    
-skip-syslogskip-syslog Do not write error messages to               
                        syslog; use error log file                   
-socket=pathsocket      The Unix socket file that the                
                        server should use when listening             
                        for  local connections                       
-syslog     syslog      Write error messages to syslog               
-timezone=timezonetimezone    Set the TZ time zone environment             
                        variable to the given option  value          
-user={user_name|user_id}user        Run the mysqld server as the user            
                        having the name user_name or the             
                        numeric user ID user_id                      

*Note `mysqld_safe': mysqld-safe.  supports the options in the
following list. It also reads option files and supports the options for
processing them described at *Note option-file-options::.

   *  `--help'

     Display a help message and exit.

   *  `--autoclose'

     (NetWare only) On NetWare, *Note `mysqld_safe': mysqld-safe.
     provides a screen presence. When you unload (shut down) the *Note
     `mysqld_safe': mysqld-safe. NLM, the screen does not by default go
     away. Instead, it prompts for user input:

          *<NLM has terminated; Press any key to close the screen>*

     If you want NetWare to close the screen automatically instead, use
     the `--autoclose' option to *Note `mysqld_safe': mysqld-safe.

   *  `--basedir=PATH'

     The path to the MySQL installation directory.

   *  `--core-file-size=SIZE'

     The size of the core file that *Note `mysqld': mysqld.  should be
     able to create. The option value is passed to `ulimit -c'.

   *  `--datadir=PATH'

     The path to the data directory.

   *  `--defaults-extra-file=PATH'

     The name of an option file to be read in addition to the usual
     option files. This must be the first option on the command line if
     it is used. If the file does not exist or is otherwise
     inaccessible, the server will exit with an error.

   *  `--defaults-file=FILE_NAME'

     The name of an option file to be read instead of the usual option
     files. This must be the first option on the command line if it is
     used.

   *  `--ledir=PATH'

     If *Note `mysqld_safe': mysqld-safe. cannot find the server, use
     this option to indicate the path name to the directory where the
     server is located.

   *  `--log-error=FILE_NAME'

     Write the error log to the given file. See *Note error-log::.

   *  `--mysqld=PROG_NAME'

     The name of the server program (in the `ledir' directory) that you
     want to start.  This option is needed if you use the MySQL binary
     distribution but have the data directory outside of the binary
     distribution. If *Note `mysqld_safe': mysqld-safe.  cannot find
     the server, use the `--ledir' option to indicate the path name to
     the directory where the server is located.

   *  `--mysqld-version=SUFFIX'

     This option is similar to the `--mysqld' option, but you specify
     only the suffix for the server program name. The basename is
     assumed to be *Note `mysqld': mysqld. For example, if you use
     `--mysqld-version=debug', *Note `mysqld_safe': mysqld-safe. starts
     the *Note `mysqld-debug': mysqld. program in the `ledir'
     directory. If the argument to `--mysqld-version' is empty, *Note
     `mysqld_safe': mysqld-safe. uses *Note `mysqld': mysqld. in the
     `ledir' directory.

   *  `--nice=PRIORITY'

     Use the `nice' program to set the server's scheduling priority to
     the given value.

   *  `--no-defaults'

     Do not read any option files. This must be the first option on the
     command line if it is used.

   *  `--open-files-limit=COUNT'

     The number of files that *Note `mysqld': mysqld. should be able to
     open. The option value is passed to `ulimit -n'. Note that you
     need to start *Note `mysqld_safe': mysqld-safe. as `root' for this
     to work properly!

   *  `--pid-file=FILE_NAME'

     The path name of the process ID file.

   *  `--port=PORT_NUM'

     The port number that the server should use when listening for
     TCP/IP connections. The port number must be 1024 or higher unless
     the server is started by the `root' system user.

   *  `--skip-kill-mysqld'

     Do not try to kill stray *Note `mysqld': mysqld. processes at
     startup. This option works only on Linux.

   *  `--socket=PATH'

     The Unix socket file that the server should use when listening for
     local connections.

   *  `--syslog', `--skip-syslog'

     `--syslog' causes error messages to be sent to `syslog' on systems
     that support the `logger' program.  `--skip-syslog' suppresses the
     use of `syslog'; messages are written to an error log file.

   *  `--syslog-tag=TAG'

     For logging to `syslog', messages from *Note `mysqld_safe':
     mysqld-safe. and *Note `mysqld': mysqld.  are written with a tag
     of `mysqld_safe' and `mysqld', respectively. To specify a suffix
     for the tag, use `--syslog-tag=TAG', which modifies the tags to be
     `mysqld_safe-TAG' and `mysqld-TAG'.

   *  `--timezone=TIMEZONE'

     Set the `TZ' time zone environment variable to the given option
     value. Consult your operating system documentation for legal time
     zone specification formats.

   *  `--user={USER_NAME|USER_ID}'

     Run the *Note `mysqld': mysqld. server as the user having the name
     USER_NAME or the numeric user ID USER_ID.  (`User' in this context
     refers to a system login account, not a MySQL user listed in the
     grant tables.)

If you execute *Note `mysqld_safe': mysqld-safe. with the
`--defaults-file' or `--defaults-extra-file' option to name an option
file, the option must be the first one given on the command line or the
option file will not be used. For example, this command will not use
the named option file:

     mysql> mysqld_safe --port=PORT_NUM --defaults-file=FILE_NAME

Instead, use the following command:

     mysql> mysqld_safe --defaults-file=FILE_NAME --port=PORT_NUM

The *Note `mysqld_safe': mysqld-safe. script is written so that it
normally can start a server that was installed from either a source or
a binary distribution of MySQL, even though these types of
distributions typically install the server in slightly different
locations. (See *Note installation-layouts::.)  *Note `mysqld_safe':
mysqld-safe. expects one of the following conditions to be true:

   * The server and databases can be found relative to the working
     directory (the directory from which *Note `mysqld_safe':
     mysqld-safe. is invoked). For binary distributions, *Note
     `mysqld_safe': mysqld-safe. looks under its working directory for
     `bin' and `data' directories. For source distributions, it looks
     for `libexec' and `var' directories. This condition should be met
     if you execute *Note `mysqld_safe': mysqld-safe. from your MySQL
     installation directory (for example, `/usr/local/mysql' for a
     binary distribution).

   * If the server and databases cannot be found relative to the
     working directory, *Note `mysqld_safe': mysqld-safe. attempts to
     locate them by absolute path names. Typical locations are
     `/usr/local/libexec' and `/usr/local/var'. The actual locations
     are determined from the values configured into the distribution at
     the time it was built. They should be correct if MySQL is
     installed in the location specified at configuration time.

Because *Note `mysqld_safe': mysqld-safe. tries to find the server and
databases relative to its own working directory, you can install a
binary distribution of MySQL anywhere, as long as you run *Note
`mysqld_safe': mysqld-safe. from the MySQL installation directory:

     shell> cd MYSQL_INSTALLATION_DIRECTORY
     shell> bin/mysqld_safe &

If *Note `mysqld_safe': mysqld-safe. fails, even when invoked from the
MySQL installation directory, you can specify the `--ledir' and
`--datadir' options to indicate the directories in which the server and
databases are located on your system.

When you use *Note `mysqld_safe': mysqld-safe. to start *Note `mysqld':
mysqld, *Note `mysqld_safe': mysqld-safe.  arranges for error (and
notice) messages from itself and from *Note `mysqld': mysqld. to go to
the same destination.

There are several *Note `mysqld_safe': mysqld-safe. options for
controlling the destination of these messages:

   * `--syslog': Write error messages to `syslog' on systems that
     support the `logger' program.

   * `--skip-syslog': Do not write error messages to `syslog'.
     Messages are written to the default error log file (`HOST_NAME.err'
     in the data directory), or to a named file if the `--log-error'
     option is given.

   * `--log-error=FILE_NAME': Write error messages to the named error
     file.

If none of these options is given, the default is `--skip-syslog'.

If `--syslog' and `--log-error' are both given, a warning is issued and
`--log-error' takes precedence.

When *Note `mysqld_safe': mysqld-safe. writes a message, notices go to
the logging destination (`syslog' or the error log file) and `stdout'.
Errors go to the logging destination and `stderr'.

Normally, you should not edit the *Note `mysqld_safe': mysqld-safe.
script. Instead, configure *Note `mysqld_safe': mysqld-safe. by using
command-line options or options in the `[mysqld_safe]' section of a
`my.cnf' option file. In rare cases, it might be necessary to edit
*Note `mysqld_safe': mysqld-safe. to get it to start the server
properly. However, if you do this, your modified version of *Note
`mysqld_safe': mysqld-safe. might be overwritten if you upgrade MySQL
in the future, so you should make a copy of your edited version that
you can reinstall.

On NetWare, *Note `mysqld_safe': mysqld-safe. is a NetWare Loadable
Module (NLM) that is ported from the original Unix shell script.  It
starts the server as follows:

  1. Runs a number of system and option checks.

  2. Runs a check on `MyISAM' tables.

  3. Provides a screen presence for the MySQL server.

  4. Starts *Note `mysqld': mysqld, monitors it, and restarts it if it
     terminates in error.

  5. Sends error messages from *Note `mysqld': mysqld. to the
     `HOST_NAME.err' file in the data directory.

  6. Sends *Note `mysqld_safe': mysqld-safe. screen output to the
     `HOST_NAME.safe' file in the data directory.


File: manual.info,  Node: mysql-server,  Next: mysqld-multi,  Prev: mysqld-safe,  Up: programs-server

4.3.3 `mysql.server' -- MySQL Server Startup Script
---------------------------------------------------

MySQL distributions on Unix include a script named *Note
`mysql.server': mysql-server. It can be used on systems such as Linux
and Solaris that use System V-style run directories to start and stop
system services. It is also used by the Mac OS X Startup Item for MySQL.

*Note `mysql.server': mysql-server. can be found in the `support-files'
directory under your MySQL installation directory or in a MySQL source
distribution.

If you use the Linux server RPM package (`MySQL-server-VERSION.rpm'),
the *Note `mysql.server': mysql-server. script will be installed in the
`/etc/init.d' directory with the name `mysql'. You need not install it
manually.  See *Note linux-rpm::, for more information on the Linux RPM
packages.

Some vendors provide RPM packages that install a startup script under a
different name such as *Note `mysqld': mysqld.

If you install MySQL from a source distribution or using a binary
distribution format that does not install *Note `mysql.server':
mysql-server. automatically, you can install it manually. Instructions
are provided in *Note automatic-start::.

*Note `mysql.server': mysql-server. reads options from the
`[mysql.server]' and `[mysqld]' sections of option files. For backward
compatibility, it also reads `[mysql_server]' sections, although you
should rename such sections to `[mysql.server]' when using MySQL 6.0.

*Note `mysql.server': mysql-server. supports the following options:

   *  `--basedir=PATH'

     The path to the MySQL installation directory.

   *  `--datadir=PATH'

     The path to the MySQL data directory.

   *  `--pid-file=FILE_NAME'

     The path name of the file in which the server should write its
     process ID.

   *  `--service-startup-timeout=FILE_NAME'

     How long in seconds to wait for confirmation of server startup. If
     the server does not start within this time, *Note `mysql.server':
     mysql-server. exits with an error. The default value is 900. A
     value of 0 means not to wait at all for startup. Negative values
     mean to wait forever (no timeout).

   *  `--use-mysqld_safe'

     Use *Note `mysqld_safe': mysqld-safe. to start the server. This is
     the default.

   *  `--user=USER_NAME'

     The login user name to use for running *Note `mysqld': mysqld.


File: manual.info,  Node: mysqld-multi,  Prev: mysql-server,  Up: programs-server

4.3.4 `mysqld_multi' -- Manage Multiple MySQL Servers
-----------------------------------------------------

*Note `mysqld_multi': mysqld-multi. is designed to manage several *Note
`mysqld': mysqld. processes that listen for connections on different
Unix socket files and TCP/IP ports. It can start or stop servers, or
report their current status.

*Note `mysqld_multi': mysqld-multi. searches for groups named
`[mysqldN]' in `my.cnf' (or in the file named by the `--config-file'
option).  N can be any positive integer. This number is referred to in
the following discussion as the option group number, or GNR. Group
numbers distinguish option groups from one another and are used as
arguments to *Note `mysqld_multi': mysqld-multi. to specify which
servers you want to start, stop, or obtain a status report for.
Options listed in these groups are the same that you would use in the
`[mysqld]' group used for starting *Note `mysqld': mysqld. (See, for
example, *Note automatic-start::.) However, when using multiple
servers, it is necessary that each one use its own value for options
such as the Unix socket file and TCP/IP port number. For more
information on which options must be unique per server in a
multiple-server environment, see *Note multiple-servers::.

To invoke *Note `mysqld_multi': mysqld-multi, use the following syntax:

     shell> mysqld_multi [OPTIONS] {start|stop|report} [GNR[,GNR] ...]

`start', `stop', and `report' indicate which operation to perform.  You
can perform the designated operation for a single server or multiple
servers, depending on the GNR list that follows the option name. If
there is no list, *Note `mysqld_multi': mysqld-multi.  performs the
operation for all servers in the option file.

Each GNR value represents an option group number or range of group
numbers. The value should be the number at the end of the group name in
the option file. For example, the GNR for a group named `[mysqld17]' is
`17'. To specify a range of numbers, separate the first and last numbers
by a dash. The GNR value `10-13' represents groups `[mysqld10]' through
`[mysqld13]'. Multiple groups or group ranges can be specified on the
command line, separated by commas. There must be no whitespace
characters (spaces or tabs) in the GNR list; anything after a whitespace
character is ignored.

This command starts a single server using option group `[mysqld17]':

     shell> mysqld_multi start 17

This command stops several servers, using option groups `[mysqld8]' and
`[mysqld10]' through `[mysqld13]':

     shell> mysqld_multi stop 8,10-13

For an example of how you might set up an option file, use this command:

     shell> mysqld_multi --example

*Note `mysqld_multi': mysqld-multi. searches for option files as
follows:

   *  With `--no-defaults', no option files are read.

   *  With `--defaults-file=FILE_NAME', only the named file is read.

   *  Otherwise, option files in the standard list of locations are
     read, including any file named by the
     `--defaults-extra-file=FILE_NAME' option, if one is given. (If the
     option is given multiple times, the last value is used.)

Option files read are searched for `[mysqld_multi]' and `[mysqldN]'
option groups.

*Note `mysqld_multi': mysqld-multi. supports the following options:

   *  `--help'

     Display a help message and exit.

   *  `--config-file=FILE_NAME'

     This option is deprecated. If given, it is treated the same way as
     `--defaults-extra-file', described earlier.

   *  `--example'

     Display a sample option file.

   *  `--log=FILE_NAME'

     Specify the name of the log file. If the file exists, log output
     is appended to it.

   *  `--mysqladmin=PROG_NAME'

     The *Note `mysqladmin': mysqladmin. binary to be used to stop
     servers.

   *  `--mysqld=PROG_NAME'

     The *Note `mysqld': mysqld. binary to be used. Note that you can
     specify *Note `mysqld_safe': mysqld-safe. as the value for this
     option also. If you use *Note `mysqld_safe': mysqld-safe. to start
     the server, you can include the `mysqld' or `ledir' options in the
     corresponding `[mysqldN]' option group. These options indicate the
     name of the server that *Note `mysqld_safe': mysqld-safe. should
     start and the path name of the directory where the server is
     located. (See the descriptions for these options in *Note
     mysqld-safe::.) Example:

          [mysqld38]
          mysqld = mysqld-debug
          ledir  = /opt/local/mysql/libexec

   *  `--no-log'

     Print log information to `stdout' rather than to the log file. By
     default, output goes to the log file.

   *  `--password=PASSWORD'

     The password of the MySQL account to use when invoking *Note
     `mysqladmin': mysqladmin. Note that the password value is not
     optional for this option, unlike for other MySQL programs.

   *  `--silent'

     Silent mode; disable warnings.

   *  `--tcp-ip'

     Connect to each MySQL server via the TCP/IP port instead of the
     Unix socket file. (If a socket file is missing, the server might
     still be running, but accessible only via the TCP/IP port.) By
     default, connections are made using the Unix socket file. This
     option affects `stop' and `report' operations.

   *  `--user=USER_NAME'

     The user name of the MySQL account to use when invoking *Note
     `mysqladmin': mysqladmin.

   *  `--verbose'

     Be more verbose.

   *  `--version'

     Display version information and exit.

Some notes about *Note `mysqld_multi': mysqld-multi.:

   * *Most important*: Before using *Note `mysqld_multi': mysqld-multi.
     be sure that you understand the meanings of the options that are
     passed to the *Note `mysqld': mysqld. servers and _why_ you would
     want to have separate *Note `mysqld': mysqld. processes. Beware of
     the dangers of using multiple *Note `mysqld': mysqld. servers with
     the same data directory. Use separate data directories, unless you
     _know_ what you are doing. Starting multiple servers with the same
     data directory does _not_ give you extra performance in a threaded
     system. See *Note multiple-servers::.

   * *Important*:

     Make sure that the data directory for each server is fully
     accessible to the Unix account that the specific *Note `mysqld':
     mysqld. process is started as.  _Do not_ use the Unix ROOT account
     for this, unless you _know_ what you are doing. See *Note
     changing-mysql-user::.

   * Make sure that the MySQL account used for stopping the *Note
     `mysqld': mysqld. servers (with the *Note `mysqladmin':
     mysqladmin. program) has the same user name and password for each
     server. Also, make sure that the account has the `SHUTDOWN'
     privilege. If the servers that you want to manage have different
     user names or passwords for the administrative accounts, you might
     want to create an account on each server that has the same user
     name and password. For example, you might set up a common
     `multi_admin' account by executing the following commands for each
     server:

          shell> mysql -u root -S /tmp/mysql.sock -p
          Enter password:
          mysql> GRANT SHUTDOWN ON *.*
              -> TO 'multi_admin'@'localhost' IDENTIFIED BY 'multipass';

     See *Note privilege-system::. You have to do this for each *Note
     `mysqld': mysqld. server. Change the connection parameters
     appropriately when connecting to each one. Note that the host name
     part of the account name must allow you to connect as
     `multi_admin' from the host where you want to run *Note
     `mysqld_multi': mysqld-multi.

   * The Unix socket file and the TCP/IP port number must be different
     for every *Note `mysqld': mysqld.  (Alternatively, if the host has
     multiple network addresses, you can use `--bind-address' to cause
     different servers to listen to different interfaces.)

   * The `--pid-file' option is very important if you are using *Note
     `mysqld_safe': mysqld-safe. to start *Note `mysqld': mysqld. (for
     example, `--mysqld=mysqld_safe') Every *Note `mysqld': mysqld.
     should have its own process ID file. The advantage of using *Note
     `mysqld_safe': mysqld-safe. instead of *Note `mysqld': mysqld. is
     that *Note `mysqld_safe': mysqld-safe. monitors its *Note
     `mysqld': mysqld. process and restarts it if the process
     terminates due to a signal sent using `kill -9' or for other
     reasons, such as a segmentation fault. Please note that the *Note
     `mysqld_safe': mysqld-safe.  script might require that you start
     it from a certain place.  This means that you might have to change
     location to a certain directory before running *Note
     `mysqld_multi': mysqld-multi. If you have problems starting,
     please see the *Note `mysqld_safe': mysqld-safe.  script. Check
     especially the lines:

          ----------------------------------------------------------------
          MY_PWD=`pwd`
          # Check if we are starting this relative (for the binary release)
          if test -d $MY_PWD/data/mysql -a \
             -f ./share/mysql/english/errmsg.sys -a \
             -x ./bin/mysqld
          ----------------------------------------------------------------

     The test performed by these lines should be successful, or you
     might encounter problems. See *Note mysqld-safe::.

   * You might want to use the `--user' option for *Note `mysqld':
     mysqld, but to do this you need to run the *Note `mysqld_multi':
     mysqld-multi. script as the Unix `root' user. Having the option in
     the option file doesn't matter; you just get a warning if you are
     not the superuser and the *Note `mysqld': mysqld.  processes are
     started under your own Unix account.

The following example shows how you might set up an option file for use
with *Note `mysqld_multi': mysqld-multi. The order in which the *Note
`mysqld': mysqld. programs are started or stopped depends on the order
in which they appear in the option file.  Group numbers need not form
an unbroken sequence. The first and fifth `[mysqldN]' groups were
intentionally omitted from the example to illustrate that you can have
`gaps' in the option file. This gives you more flexibility.

     # This file should probably be in your home dir (~/.my.cnf)
     # or /etc/my.cnf
     # Version 2.1 by Jani Tolonen

     [mysqld_multi]
     mysqld     = /usr/local/bin/mysqld_safe
     mysqladmin = /usr/local/bin/mysqladmin
     user       = multi_admin
     password   = multipass

     [mysqld2]
     socket     = /tmp/mysql.sock2
     port       = 3307
     pid-file   = /usr/local/mysql/var2/hostname.pid2
     datadir    = /usr/local/mysql/var2
     language   = /usr/local/share/mysql/english
     user       = john

     [mysqld3]
     socket     = /tmp/mysql.sock3
     port       = 3308
     pid-file   = /usr/local/mysql/var3/hostname.pid3
     datadir    = /usr/local/mysql/var3
     language   = /usr/local/share/mysql/swedish
     user       = monty

     [mysqld4]
     socket     = /tmp/mysql.sock4
     port       = 3309
     pid-file   = /usr/local/mysql/var4/hostname.pid4
     datadir    = /usr/local/mysql/var4
     language   = /usr/local/share/mysql/estonia
     user       = tonu

     [mysqld6]
     socket     = /tmp/mysql.sock6
     port       = 3311
     pid-file   = /usr/local/mysql/var6/hostname.pid6
     datadir    = /usr/local/mysql/var6
     language   = /usr/local/share/mysql/japanese
     user       = jani

See *Note option-files::.


File: manual.info,  Node: programs-installation,  Next: programs-client,  Prev: programs-server,  Up: programs

4.4 MySQL Installation-Related Programs
=======================================

* Menu:

* comp-err::                     `comp_err' --- Compile MySQL Error Message File
* make-win-bin-dist::            `make_win_bin_dist' --- Package MySQL Distribution as ZIP Archive
* mysqlbug::                     `mysqlbug' --- Generate Bug Report
* mysql-fix-privilege-tables::   `mysql_fix_privilege_tables' --- Upgrade MySQL System Tables
* mysql-install-db::             `mysql_install_db' --- Initialize MySQL Data Directory
* mysql-secure-installation::    `mysql_secure_installation' --- Improve MySQL Installation Security
* mysql-tzinfo-to-sql::          `mysql_tzinfo_to_sql' --- Load the Time Zone Tables
* mysql-upgrade::                `mysql_upgrade' --- Check Tables for MySQL Upgrade

The programs in this section are used when installing or upgrading
MySQL.


File: manual.info,  Node: comp-err,  Next: make-win-bin-dist,  Prev: programs-installation,  Up: programs-installation

4.4.1 `comp_err' -- Compile MySQL Error Message File
----------------------------------------------------

*Note `comp_err': comp-err. creates the `errmsg.sys' file that is used
by *Note `mysqld': mysqld. to determine the error messages to display
for different error codes. *Note `comp_err': comp-err.  normally is run
automatically when MySQL is built. It compiles the `errmsg.sys' file
from the plaintext file located at `sql/share/errmsg.txt' in MySQL
source distributions.

*Note `comp_err': comp-err. also generates `mysqld_error.h',
`mysqld_ername.h', and `sql_state.h' header files.

For more information about how error messages are defined, see the
MySQL Internals Manual.

Invoke *Note `comp_err': comp-err. like this:

     shell> comp_err [OPTIONS]

*Note `comp_err': comp-err. supports the options described in the
following list.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--charset=PATH, -C PATH'

     The character set directory. The default is
     `../sql/share/charsets'.

   *  `--debug=DEBUG_OPTIONS, -# DEBUG_OPTIONS'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:O,FILE_NAME''.  The default is `'d:t:O,/tmp/comp_err.trace''.

   *  `--debug-info', `-T'

     Print some debugging information when the program exits.

   *  `--header_file=FILE_NAME, -H FILE_NAME'

     The name of the error header file. The default is `mysqld_error.h'.

   *  `--in_file=FILE_NAME, -F FILE_NAME'

     The name of the input file. The default is
     `../sql/share/errmsg.txt'.

   *  `--name_file=FILE_NAME, -N FILE_NAME'

     The name of the error name file. The default is `mysqld_ername.h'.

   *  `--out_dir=PATH, -D PATH'

     The name of the output base directory. The default is
     `../sql/share/'.

   *  `--out_file=FILE_NAME, -O FILE_NAME'

     The name of the output file. The default is `errmsg.sys'.

   *  `--statefile=FILE_NAME, -S FILE_NAME'

     The name for the SQLSTATE header file. The default is
     `sql_state.h'.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: make-win-bin-dist,  Next: mysqlbug,  Prev: comp-err,  Up: programs-installation

4.4.2 `make_win_bin_dist' -- Package MySQL Distribution as ZIP Archive
----------------------------------------------------------------------

This script is used on Windows after building a MySQL distribution from
source to create executable programs. It packages the binaries and
support files into a ZIP archive that can be unpacked at the location
where you want to install MySQL.

*Note `make_win_bin_dist': make-win-bin-dist. is a shell script, so you
must have Cygwin installed to use it.

This program's use is subject to change. Currently, you invoke it as
follows from the root directory of your source distribution:

     shell> make_win_bin_dist [OPTIONS] PACKAGE_BASENAME [COPY_DEF ...]

The PACKAGE_BASENAME argument provides the basename for the resulting
ZIP archive. This name will be the name of the directory that results
from unpacking the archive.

Because you might want to include files of directories from other
builds, you can instruct this script do copy them in for you, via
COPY_DEF arguments, which of which is of the form
RELATIVE_DEST_NAME=SOURCE_NAME.

Example:

     bin/mysqld-max.exe=../my-max-build/sql/release/mysqld.exe

If you specify a directory, the entire directory will be copied.

*Note `make_win_bin_dist': make-win-bin-dist. supports the following
options:

   *  `--debug'

     Pack the debug binaries and produce an error if they were not
     built.

   *  `--embedded'

     Pack the embedded server and produce an error if it was not built.
     The default is to pack it if it was built.

   *  `--exe-suffix=SUFFIX'

     Add a suffix to the basename of the *Note `mysql': mysql.  binary.
     For example, a suffix of `-abc' produces a binary named
     `mysqld-abc.exe'.

   *  `--no-debug'

     Don't pack the debug binaries even if they were built.

   *  `--no-embedded'

     Don't pack the embedded server even if it was built.

   *  `--only-debug'

     Use this option when the target for this build was `Debug', and
     you just want to replace the normal binaries with debug versions
     (that is, do not use separate `debug' directories).


File: manual.info,  Node: mysqlbug,  Next: mysql-fix-privilege-tables,  Prev: make-win-bin-dist,  Up: programs-installation

4.4.3 `mysqlbug' -- Generate Bug Report
---------------------------------------

This program enables you to generate a bug report and send it to MySQL
AB. It is a shell script and runs on Unix.

The normal way to report bugs is to visit `http://bugs.mysql.com/',
which is the address for our bugs database. This database is public and
can be browsed and searched by anyone. If you log in to the system, you
can enter new reports. If you have no Web access, you can generate a
bug report by using the *Note `mysqlbug': mysqlbug. script.

*Note `mysqlbug': mysqlbug. helps you generate a report by determining
much of the following information automatically, but if something
important is missing, please include it with your message. *Note
`mysqlbug': mysqlbug. can be found in the `scripts' directory (source
distribution) and in the `bin' directory under your MySQL installation
directory (binary distribution).

Invoke *Note `mysqlbug': mysqlbug. without arguments:

     shell> mysqlbug

The script will place you in an editor with a copy of the report to be
sent. Edit the lines near the beginning that indicate the nature of the
problem. Then write the file to save your changes, quit the editor, and
*Note `mysqlbug': mysqlbug. will send the report by email.


File: manual.info,  Node: mysql-fix-privilege-tables,  Next: mysql-install-db,  Prev: mysqlbug,  Up: programs-installation

4.4.4 `mysql_fix_privilege_tables' -- Upgrade MySQL System Tables
-----------------------------------------------------------------

Some releases of MySQL introduce changes to the structure of the system
tables in the `mysql' database to add new privileges or support new
features. When you update to a new version of MySQL, you should update
your system tables as well to make sure that their structure is up to
date. Otherwise, there might be capabilities that you cannot take
advantage of.

*Note `mysql_fix_privilege_tables': mysql-fix-privilege-tables. is an
older script that previously was used to uprade the system tables in the
`mysql' database after a MySQL upgrade.

*Note*:

As of MySQL 5.1.7, *Note `mysql_fix_privilege_tables':
mysql-fix-privilege-tables. is superseded by *Note `mysql_upgrade':
mysql-upgrade, which should be used instead. See *Note mysql-upgrade::.

Before running *Note `mysql_fix_privilege_tables':
mysql-fix-privilege-tables, make a backup of your `mysql' database.

On Unix or Unix-like systems, update the system tables by running the
*Note `mysql_fix_privilege_tables': mysql-fix-privilege-tables.  script:

     shell> mysql_fix_privilege_tables

You must run this script while the server is running. It attempts to
connect to the server running on the local host as `root'. If your
`root' account requires a password, indicate the password on the
command line like this:

     shell> mysql_fix_privilege_tables --password=ROOT_PASSWORD

The *Note `mysql_fix_privilege_tables': mysql-fix-privilege-tables.
script performs any actions necessary to convert your system tables to
the current format. You might see some `Duplicate column name' warnings
as it runs; you can ignore them.

After running the script, stop the server and restart it so that any
changes made to the system tables take effect.

On Windows systems, MySQL distributions include a
`mysql_fix_privilege_tables.sql' SQL script that you can run using the
*Note `mysql': mysql. client. For example, if your MySQL installation
is located at `C:\Program Files\MySQL\MySQL Server 6.0', the commands
look like this:

     C:\> cd "C:\Program Files\MySQL\MySQL Server 6.0"
     C:\> bin\mysql -u root -p mysql
     mysql> SOURCE scripts/mysql_fix_privilege_tables.sql

The *Note `mysql': mysql. command will prompt you for the `root'
password; enter it when prompted.

If your installation is located in some other directory, adjust the
path names appropriately.

As with the Unix procedure, you might see some `Duplicate column name'
warnings as *Note `mysql': mysql. processes the statements in the
`mysql_fix_privilege_tables.sql' script; you can ignore them.

After running the script, stop the server and restart it.


File: manual.info,  Node: mysql-install-db,  Next: mysql-secure-installation,  Prev: mysql-fix-privilege-tables,  Up: programs-installation

4.4.5 `mysql_install_db' -- Initialize MySQL Data Directory
-----------------------------------------------------------

*Note `mysql_install_db': mysql-install-db. initializes the MySQL data
directory and creates the system tables that it contains, if they do
not exist.

To invoke *Note `mysql_install_db': mysql-install-db, use the following
syntax:

     shell> mysql_install_db [OPTIONS]

Because the MySQL server, *Note `mysqld': mysqld, needs to access the
data directory when it runs later, you should either run *Note
`mysql_install_db': mysql-install-db. from the same account that will
be used for running *Note `mysqld': mysqld. or run it as `root' and use
the `--user' option to indicate the user name that *Note `mysqld':
mysqld. will run as. It might be necessary to specify other options
such as `--basedir' or `--datadir' if *Note `mysql_install_db':
mysql-install-db. does not use the correct locations for the
installation directory or data directory. For example:

     shell> bin/mysql_install_db --user=mysql \
              --basedir=/opt/mysql/mysql \
              --datadir=/opt/mysql/mysql/data

*Note `mysql_install_db': mysql-install-db. needs to invoke *Note
`mysqld': mysqld. with the `--bootstrap' and `--skip-grant-tables'
options (see *Note configure-options::). If MySQL was configured with
the `--disable-grant-options' option, `--bootstrap' and
`--skip-grant-tables' will be disabled. To handle this, set the
`MYSQLD_BOOTSTRAP' environment variable to the full path name of a
server that has all options enabled.  *Note `mysql_install_db':
mysql-install-db. will use that server.

*Note `mysql_install_db': mysql-install-db. supports the options in the
following list. It also reads option files and supports the options for
processing them described at *Note option-file-options::.

   *  `--basedir=PATH'

     The path to the MySQL installation directory.

   *  `--force'

     Causes *Note `mysql_install_db': mysql-install-db. to run even if
     DNS does not work. In that case, grant table entries that normally
     use host names will use IP addresses.

   *  `--datadir=PATH', `--ldata=PATH'

     The path to the MySQL data directory.

   *  `--rpm'

     For internal use. This option is used by RPM files during the
     MySQL installation process.

   *  `--skip-name-resolve'

     Use IP addresses rather than host names when creating grant table
     entries. This option can be useful if your DNS does not work.

   *  `--srcdir=PATH'

     For internal use. The directory under which *Note
     `mysql_install_db': mysql-install-db. looks for support files such
     as the error message file and the file for populating the help
     tables. This option was added in MySQL 5.1.14.

   *  `--user=USER_NAME'

     The login user name to use for running *Note `mysqld': mysqld.
     Files and directories created by *Note `mysqld': mysqld. will be
     owned by this user. You must be `root' to use this option. By
     default, *Note `mysqld': mysqld. runs using your current login
     name and files and directories that it creates will be owned by
     you.

   *  `--verbose'

     Verbose mode. Print more information about what the program does.

   *  `--windows'

     For internal use. This option is used for creating Windows
     distributions.


File: manual.info,  Node: mysql-secure-installation,  Next: mysql-tzinfo-to-sql,  Prev: mysql-install-db,  Up: programs-installation

4.4.6 `mysql_secure_installation' -- Improve MySQL Installation Security
------------------------------------------------------------------------

This program enables you to improve the security of your MySQL
installation in the following ways:

   * You can set a password for `root' accounts.

   * You can remove `root' accounts that are accessible from outside
     the local host.

   * You can remove anonymous-user accounts.

   * You can remove the `test' database, which by default can be
     accessed by anonymous users.

Invoke *Note `mysql_secure_installation': mysql-secure-installation.
without arguments:

     shell> mysql_secure_installation

The script will prompt you to determine which actions to perform.


File: manual.info,  Node: mysql-tzinfo-to-sql,  Next: mysql-upgrade,  Prev: mysql-secure-installation,  Up: programs-installation

4.4.7 `mysql_tzinfo_to_sql' -- Load the Time Zone Tables
--------------------------------------------------------

The *Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql. program loads the
time zone tables in the `mysql' database. It is used on systems that
have a _zoneinfo_ database (the set of files describing time zones).
Examples of such systems are Linux, FreeBSD, Sun Solaris, and Mac OS X.
One likely location for these files is the `/usr/share/zoneinfo'
directory (`/usr/share/lib/zoneinfo' on Solaris). If your system does
not have a zoneinfo database, you can use the downloadable package
described in *Note time-zone-support::.

*Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql. can be invoked several
ways:

     shell> mysql_tzinfo_to_sql TZ_DIR
     shell> mysql_tzinfo_to_sql TZ_FILE TZ_NAME
     shell> mysql_tzinfo_to_sql --leap TZ_FILE

For the first invocation syntax, pass the zoneinfo directory path name
to *Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql. and send the
output into the *Note `mysql': mysql. program. For example:

     shell> mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root mysql

*Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql. reads your system's
time zone files and generates SQL statements from them.  *Note `mysql':
mysql. processes those statements to load the time zone tables.

The second syntax causes *Note `mysql_tzinfo_to_sql':
mysql-tzinfo-to-sql.  to load a single time zone file TZ_FILE that
corresponds to a time zone name TZ_NAME:

     shell> mysql_tzinfo_to_sql TZ_FILE TZ_NAME | mysql -u root mysql

If your time zone needs to account for leap seconds, invoke *Note
`mysql_tzinfo_to_sql': mysql-tzinfo-to-sql. using the third syntax,
which initializes the leap second information.  TZ_FILE is the name of
your time zone file:

     shell> mysql_tzinfo_to_sql --leap TZ_FILE | mysql -u root mysql

After running *Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql, it is
best to restart the server so that it does not continue to use any
previously cached time zone data.


File: manual.info,  Node: mysql-upgrade,  Prev: mysql-tzinfo-to-sql,  Up: programs-installation

4.4.8 `mysql_upgrade' -- Check Tables for MySQL Upgrade
-------------------------------------------------------

*Note `mysql_upgrade': mysql-upgrade. should be executed each time you
upgrade MySQL. It supersedes the older *Note
`mysql_fix_privilege_tables': mysql-fix-privilege-tables. script, which
should no longer be used.

*Note `mysql_upgrade': mysql-upgrade. checks all tables in all
databases for incompatibilities with the current version of MySQL
Server. If a table is found to have a possible incompatibility, it is
checked. If any problems are found, the table is repaired. *Note
`mysql_upgrade': mysql-upgrade. also upgrades the system tables so that
you can take advantage of new privileges or capabilities that might
have been added.

All checked and repaired tables are marked with the current MySQL
version number. This ensures that next time you run *Note
`mysql_upgrade': mysql-upgrade. with the same version of the server, it
can tell whether there is any need to check or repair the table again.

*Note `mysql_upgrade': mysql-upgrade. also saves the MySQL version
number in a file named `mysql_upgrade_info' in the data directory. This
is used to quickly check if all tables have been checked for this
release so that table-checking can be skipped. To ignore this file, use
the `--force' option.

*Caution*:

Some upgrade incompatibilities may require special handling _before_
you upgrade your MySQL installation and run *Note `mysql_upgrade':
mysql-upgrade. See *Note upgrade::, for instructions on determining
whether any such incompatibilities apply to your installation and how
to handle them.

*Note `mysql_upgrade': mysql-upgrade. executes the following commands
to check and repair tables and to upgrade the system tables.
FIX_PRIV_TABLES represents a script generated interally by *Note
`mysql_upgrade': mysql-upgrade. that contains SQL statements to upgrade
the tables in the `mysql' database:

     mysqlcheck --check-upgrade --all-databases --auto-repair
     mysql < FIX_PRIV_TABLES
     mysqlcheck --all-databases --check-upgrade --fix-db-names --fix-table-names

*Note*:

Prior to MySQL 6.0.10, *Note `mysql_upgrade': mysql-upgrade. does not
run the third command, which is necessary to re-encode database or
table names that contain non-alphanumeric characters. (They still
appear after the upgrade with the `#mysql50#' prefix described in *Note
identifier-mapping::.) If you have such database or table names,
execute the third command manually after executing *Note
`mysql_upgrade': mysql-upgrade.

For details about what is checked, see the description of the `FOR
UPGRADE' option of the *Note `CHECK TABLE': check-table. statement (see
*Note check-table::).

In MySQL 5.1.7, `mysql_upgrade ' was added as a shell script and worked
only for Unix systems. As of MySQL 5.1.10, *Note `mysql_upgrade':
mysql-upgrade. is an executable binary and is available on all systems.

If you install MySQL from RPM packages on Linux, you must install the
server and client RPMs.  *Note `mysql_upgrade': mysql-upgrade. is
included in the server RPM but requires the client RPM because the
latter includes *Note `mysqlcheck': mysqlcheck. (See *Note linux-rpm::.)

To use *Note `mysql_upgrade': mysql-upgrade, make sure that the server
is running, and then invoke it like this:

     shell> mysql_upgrade [OPTIONS]

After running *Note `mysql_upgrade': mysql-upgrade, stop the server and
restart it so that any changes made to the system tables take effect.

*Note `mysql_upgrade': mysql-upgrade. supports the options in the
following list. It also reads option files (the `[mysql_upgrade]' and
`[client]' groups) and supports the options for processing them
described at *Note option-file-options::. Other options are passed to
*Note `mysqlcheck': mysqlcheck. For example, it might be necessary to
specify the `--password[=PASSWORD]' option.

   *  `--help'

     Display a short help message and exit.

   *  `--basedir=PATH'

     The path to the MySQL installation directory.

   *  `--datadir=PATH'

     The path to the data directory.

   *  `--debug-check'

     Print some debugging information when the program exits.

   *  `--debug-info', `-T'

     Print debugging information and memory and CPU usage statistics
     when the program exits.

   *  `--force'

     Ignore the `mysql_upgrade_info' file and force execution of *Note
     `mysqlcheck': mysqlcheck. even if *Note `mysql_upgrade':
     mysql-upgrade. has already been executed for the current version
     of MySQL.

   *  `--tmpdir=PATH', `-t PATH'

     The path name of the directory to use for creating temporary
     files. This option was added in MySQL 6.0.6.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL user name to use when connecting to the server.  The
     default user name is `root'.

   *  `--verbose'

     Verbose mode. Print more information about what the program does.


File: manual.info,  Node: programs-client,  Next: programs-admin-utils,  Prev: programs-installation,  Up: programs

4.5 MySQL Client Programs
=========================

* Menu:

* mysql::                        `mysql' --- The MySQL Command-Line Tool
* mysqladmin::                   `mysqladmin' --- Client for Administering a MySQL Server
* mysqlcheck::                   `mysqlcheck' --- A Table Maintenance and Repair Program
* mysqldump::                    `mysqldump' --- A Database Backup Program
* mysqlimport::                  `mysqlimport' --- A Data Import Program
* mysqlshow::                    `mysqlshow' --- Display Database, Table, and Column Information
* mysqlslap::                    `mysqlslap' --- Load Emulation Client


File: manual.info,  Node: mysql,  Next: mysqladmin,  Prev: programs-client,  Up: programs-client

4.5.1 `mysql' -- The MySQL Command-Line Tool
--------------------------------------------

* Menu:

* mysql-command-options::        `mysql' Options
* mysql-commands::               `mysql' Commands
* mysql-server-side-help::       `mysql' Server-Side Help
* batch-commands::               Executing SQL Statements from a Text File
* mysql-tips::                   `mysql' Tips

*Note `mysql': mysql. is a simple SQL shell (with GNU `readline'
capabilities). It supports interactive and non-interactive use. When
used interactively, query results are presented in an ASCII-table
format. When used non-interactively (for example, as a filter), the
result is presented in tab-separated format. The output format can be
changed using command options.

If you have problems due to insufficient memory for large result sets,
use the `--quick' option. This forces *Note `mysql': mysql. to retrieve
results from the server a row at a time rather than retrieving the
entire result set and buffering it in memory before displaying it. This
is done by returning the result set using the *Note
`mysql_use_result()': mysql-use-result. C API function in the
client/server library rather than *Note `mysql_store_result()':
mysql-store-result.

Using *Note `mysql': mysql. is very easy. Invoke it from the prompt of
your command interpreter as follows:

     shell> mysql DB_NAME

Or:

     shell> mysql --user=USER_NAME --password=YOUR_PASSWORD DB_NAME

Then type an SQL statement, end it with ``;'', `\g', or `\G' and press
Enter.

Typing Control-C causes *Note `mysql': mysql. to attempt to kill the
current statement. If this cannot be done, or Control-C is typed again
before the statement is killed, *Note `mysql': mysql. exits.
Previously, Control-C caused *Note `mysql': mysql. to exit in all cases.

You can execute SQL statements in a script file (batch file) like this:

     shell> mysql DB_NAME < SCRIPT.SQL > OUTPUT.TAB


File: manual.info,  Node: mysql-command-options,  Next: mysql-commands,  Prev: mysql,  Up: mysql

4.5.1.1 `mysql' Options
.......................

*`mysql' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-auto-rehashauto-rehash Enable automatic rehashing                   
-auto-vertical-outputauto-vertical-outputEnable automatic vertical result     6.0.4   
                        set display                                  
-batch      batch       Don't use history file                       
-bind-address=host_name            Determine which client network               
                        interface (IP address or host name)          
                        to use when connecting to the                
                        MySQL Server                                 
-character-sets-dir=namecharacter-sets-dirSet the default character set                
-column-namescolumn-namesWrite column names in results                
-column-type-infocolumn-type-infoDisplay result set metadata                  
-comments   comments    Whether to retain or strip comments  6.0.4   
                        in statements sent to the  server            
-compress   compress    Compress all information sent                
                        between the client and the server            
-connect_timeout=valueconnect_timeoutThe number of seconds before                 
                        connection timeout                           
-database=dbnamedatabase    The database to use                          
-debug[=debug_options]debug       Write a debugging log                        
-debug-checkdebug-check Print debugging information when             
                        the program exits                            
-debug-info debug-info  Print debugging information, memory          
                        and CPU statistics when the                  
                        program exits                                
-default-character-set=charset_namedefault-character-setUse charset_name as the default              
                        character set                                
-delimiter=strdelimiter   Set the statement delimiter                  
-execute=statementexecute     Execute the statement and quit               
-force      force       Continue even if an SQL error occurs         
-help                   Display help message and exit                
-host=host_namehost        Connect to the MySQL server on the           
                        given host                                   
-html       html        Produce HTML output                          
-ignore-spacesignore-spacesIgnore spaces after function names           
-line-numbersline-numbersWrite line numbers for errors                
-local-infile[={0|1}]local-infileEnable or disable for LOCAL                  
                        capability for LOAD DATA INFILE              
-max_allowed_packet=valuemax_allowed_packetThe maximum packet length to send            
                        to or receive from the server                
-max_join_size=valuemax_join_sizeThe automatic limit for rows in a            
                        join when using -safe-updates                
-named-commandsnamed-commandsEnable named mysql commands                  
-net_buffer_length=valuenet_buffer_lengthThe buffer size for TCP/IP and               
                        socket communication                         
-no-auto-rehash            Disable automatic rehashing                  
-no-beep    no-beep     Do not beep when errors occur                
-no-named-commandsno-named-commandsDisable named mysql commands                 
-no-pager   no-pager    Deprecated form of -skip-pager               
-no-tee     no-tee      Do not copy output to a file                 
-one-databaseone-databaseIgnore statements except those for           
                        the default database named on  the           
                        command line                                 
-pager[=command]pager       Use the given command for paging             
                        query output                                 
-password[=password]password    The password to use when connecting          
                        to the server                                
-port=port_numport        The TCP/IP port number to use for            
                        the connection                               
-prompt=format_strprompt      Set the prompt to the specified              
                        format                                       
-protocol=typeprotocol    The connection protocol to use               
-quick      quick       Do not cache each query result               
-raw        raw         Write column values without escape           
                        conversion                                   
-reconnect  reconnect   If the connection to the server is           
                        lost, automatically try to                   
                        reconnect                                    
-safe-updatessafe-updatesAllow only UPDATE and DELETE                 
                        statements that specify key values           
-secure-authsecure-auth Do not send passwords to the server          
                        in old (pre-4.1.1) format                    
-select_limit=valueselect_limitThe automatic limit for SELECT               
                        statements when using  -safe-updates         
-show-warningsshow-warningsShow warnings after each statement           
                        if there are any                             
-sigint-ignoresigint-ignoreIgnore SIGINT signals (typically             
                        the result of typing Control-C)              
-silent     silent      Silent mode                                  
-skip-auto-rehashskip-auto-rehashDisable automatic rehashing                  
-skip-column-namesskip-column-namesDo not write column names in results         
-skip-line-numbersskip-line-numbersSkip line numbers for errors                 
-skip-named-commandsskip-named-commandsDisable named mysql commands                 
-skip-pager skip-pager  Disable paging                               
-skip-reconnectskip-reconnectDisable reconnecting                         
-socket=pathsocket      For connections to localhost                 
-ssl-ca=file_namessl-ca      The path to a file that contains a           
                        list of trusted SSL CAs                      
-ssl-capath=directory_namessl-capath  The path to a directory that                 
                        contains trusted SSL CA                      
                        certificates  in PEM format                  
-ssl-cert=file_namessl-cert    The name of the SSL certificate              
                        file to use for establishing a               
                        secure connection                            
-ssl-cipher=cipher_listssl-cipher  A list of allowable ciphers to use           
                        for SSL encryption                           
-ssl-key=file_namessl-key     The name of the SSL key file to use          
                        for establishing a secure                    
                        connection                                   
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in            
                        its certificate is verified                  
                        against the host name used when              
                        connecting to the server                     
-table      table       Display output in tabular format             
-tee=file_nametee         Append a copy of output to the               
                        given file                                   
-unbuffered unbuffered  Flush the buffer after each query            
-user=user_nameuser        The MySQL user name to use when              
                        connecting to the server                     
-verbose                Verbose mode                                 
-version                Display version information and exit         
-vertical   vertical    Print query output rows vertically           
                        (one line per column value)                  
-wait       wait        If the connection cannot be                  
                        established, wait and retry instead          
                        of  aborting                                 
-xml        xml         Produce XML output                           

*Note `mysql': mysql. supports the options in the following list. It
also reads option files and supports the options for processing them
described at *Note option-file-options::.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--auto-rehash'

     Enable automatic rehashing. This option is on by default, which
     enables database, table, and column name completion.  Use
     `--disable-auto-rehash' to disable rehashing. That causes *Note
     `mysql': mysql.  to start faster, but you must issue the `rehash'
     command if you want to use name completion.

     To complete a name, enter the first part and press Tab. If the
     name is unambiguous, *Note `mysql': mysql. completes it.
     Otherwise, you can press Tab again to see the possible names that
     begin with what you have typed so far. Completion does not occur
     if there is no default database.

   *  `--auto-vertical-output'

     Causes result sets to be displayed vertically if they are too wide
     for the current window, and using normal tabular format otherwise.
     (This applies to statements terminated by `;' or `\G'.) This option
     was added in MySQL 6.0.4.

   *  `--batch', `-B'

     Print results using tab as the column separator, with each row on
     a new line. With this option, *Note `mysql': mysql. does not use
     the history file.

     Batch mode results in non-tabular output format and escaping of
     special characters. Escaping may be disabled by using raw mode;
     see the description for the `--raw' option.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--column-names'

     Write column names in results.

   *  `--column-type-info', `-m'

     Display result set metadata.

   *  `--comments', `-c'

     Whether to preserve comments in statements sent to the server. The
     default is -skip-comments (discard comments), enable with
     -comments (preserve comments). This option was added in MySQL
     6.0.4.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--database=DB_NAME', `-D DB_NAME'

     The database to use. This is useful primarily in an option file.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is `'d:t:o,/tmp/mysql.trace''.

   *  `--debug-check'

     Print some debugging information when the program exits.

   *  `--debug-info', `-T'

     Print debugging information and memory and CPU usage statistics
     when the program exits.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.

   *  `--delimiter=STR'

     Set the statement delimiter. The default is the semicolon
     character (``;'').

   *  `--disable-named-commands'

     Disable named commands. Use the `\*' form only, or use named
     commands only at the beginning of a line ending with a semicolon
     (``;'').  *Note `mysql': mysql. starts with this option _enabled_
     by default. However, even with this option, long-format commands
     still work from the first line. See *Note mysql-commands::.

   *  `--execute=STATEMENT', `-e STATEMENT'

     Execute the statement and quit. The default output format is like
     that produced with `--batch'. See *Note command-line-options::,
     for some examples.

   *  `--force', `-f'

     Continue even if an SQL error occurs.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--html', `-H'

     Produce HTML output.

   *  `--ignore-spaces', `-i'

     Ignore spaces after function names. The effect of this is
     described in the discussion for the `IGNORE_SPACE' SQL mode (see
     *Note server-sql-mode::).

   *  `--line-numbers'

     Write line numbers for errors. Disable this with
     `--skip-line-numbers'.

   *  `--local-infile[={0|1}]'

     Enable or disable `LOCAL' capability for *Note `LOAD DATA INFILE':
     load-data. With no value, the option enables `LOCAL'. The option
     may be given as `--local-infile=0' or `--local-infile=1' to
     explicitly disable or enable `LOCAL'. Enabling `LOCAL' has no
     effect if the server does not also support it.

     MySQL Enterprise

     For expert advice on the security implications of enabling
     `LOCAL', subscribe to the MySQL Enterprise Monitor. For more
     information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--named-commands', `-G'

     Enable named *Note `mysql': mysql. commands. Long-format commands
     are allowed, not just short-format commands. For example, `quit'
     and `\q' both are recognized. Use `--skip-named-commands' to
     disable named commands. See *Note mysql-commands::.

   *  `--no-auto-rehash', `-A'

     Deprecated form of `-skip-auto-rehash'.  Use
     `--disable-auto-rehash' instead. See the description for
     `--auto-rehash'.

   *  `--no-beep', `-b'

     Do not beep when errors occur.

   *  `--no-named-commands', `-g'

     Deprecated, use `--disable-named-commands' instead.

   *  `--no-pager'

     Deprecated form of `--skip-pager'.  See the `--pager' option.

   *  `--no-tee'

     Do not copy output to a file.  *Note mysql-commands::, discusses
     tee files further.

   *  `--one-database', `-o'

     Ignore statements except those for the default database named on
     the command line. This is useful for skipping updates to other
     databases in the binary log.

   *  `--pager[=COMMAND]'

     Use the given command for paging query output. If the command is
     omitted, the default pager is the value of your `PAGER'
     environment variable. Valid pagers are `less', `more', `cat [>
     filename]', and so forth. This option works only on Unix. It does
     not work in batch mode.  To disable paging, use `--skip-pager'.
     *Note mysql-commands::, discusses output paging further.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--prompt=FORMAT_STR'

     Set the prompt to the specified format. The default is `mysql>'.
     The special sequences that the prompt can contain are described in
     *Note mysql-commands::.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--quick', `-q'

     Do not cache each query result, print each row as it is received.
     This may slow down the server if the output is suspended. With
     this option, *Note `mysql': mysql. does not use the history file.

   *  `--raw', `-r'

     For tabular output, the `boxing' around columns enables one column
     value to be distinguished from another.  For non-tabular output
     (such as is produced in batch mode or when the `--batch' or
     `--silent' option is given), special characters are escaped in the
     output so they can be identified easily. Newline, tab, `NUL', and
     backslash are written as `\n', `\t', `\0', and `\\'. The `--raw'
     option disables this character escaping.

     The following example demonstrates tabular versus non-tabular
     output and the use of raw mode to disable escaping:

          % mysql
          mysql> SELECT CHAR(92);
          +----------+
          | CHAR(92) |
          +----------+
          | \        |
          +----------+

          % mysql -s
          mysql> SELECT CHAR(92);
          CHAR(92)
          \\

          % mysql -s -r
          mysql> SELECT CHAR(92);
          CHAR(92)
          \

   *  `--reconnect'

     If the connection to the server is lost, automatically try to
     reconnect. A single reconnect attempt is made each time the
     connection is lost. To suppress reconnection behavior, use
     `--skip-reconnect'.

   *  `--safe-updates', `--i-am-a-dummy', `-U'

     Allow only those *Note `UPDATE': update. and *Note `DELETE':
     delete. statements that specify which rows to modify by using key
     values. If you have set this option in an option file, you can
     override it by using `--safe-updates' on the command line. See
     *Note mysql-tips::, for more information about this option.

   *  `--secure-auth'

     Do not send passwords to the server in old (pre-4.1.1) format.
     This prevents connections except for servers that use the newer
     password format.

     MySQL Enterprise

     For expert advice on database security, subscribe to the MySQL
     Enterprise Monitor. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--show-warnings'

     Cause warnings to be shown after each statement if there are any.
     This option applies to interactive and batch mode.

   *  `--sigint-ignore'

     Ignore `SIGINT' signals (typically the result of typing Control-C).

   *  `--silent', `-s'

     Silent mode. Produce less output. This option can be given
     multiple times to produce less and less output.

     This option results in non-tabular output format and escaping of
     special characters. Escaping may be disabled by using raw mode;
     see the description for the `--raw' option.

   *  `--skip-column-names', `-N'

     Do not write column names in results. The short format, `-N' is
     deprecated, use the long format instead.

   *  `--skip-line-numbers', `-L'

     Do not write line numbers for errors. Useful when you want to
     compare result files that include error messages. The short
     format, `-L' is deprecated, use the long format instead.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--table', `-t'

     Display output in table format. This is the default for
     interactive use, but can be used to produce table output in batch
     mode.

   *  `--tee=FILE_NAME'

     Append a copy of output to the given file. This option does not
     work in batch mode. *Note mysql-commands::, discusses tee files
     further.

   *  `--unbuffered', `-n'

     Flush the buffer after each query.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL user name to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Produce more output about what the program does.
     This option can be given multiple times to produce more and more
     output. (For example, `-v -v -v' produces table output format even
     in batch mode.)

   *  `--version', `-V'

     Display version information and exit.

   *  `--vertical', `-E'

     Print query output rows vertically (one line per column value).
     Without this option, you can specify vertical output for
     individual statements by terminating them with `\G'.

   *  `--wait', `-w'

     If the connection cannot be established, wait and retry instead of
     aborting.

   *  `--xml', `-X'

     Produce XML output.

          <field name="COLUMN_NAME">NULL</field>

     The output when `--xml' is used with *Note `mysql': mysql. matches
     that of *Note `mysqldump `--xml'': mysqldump. See *Note
     mysqldump:: for details.

     The XML output also uses an XML namespace, as shown here:

          shell> mysql --xml -uroot -e "SHOW VARIABLES LIKE 'version%'"
          <?xml version="1.0"?>

          <resultset statement="SHOW VARIABLES LIKE 'version%'" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
          <row>
          <field name="Variable_name">version</field>
          <field name="Value">5.0.40-debug</field>
          </row>

          <row>
          <field name="Variable_name">version_comment</field>
          <field name="Value">Source distribution</field>
          </row>

          <row>
          <field name="Variable_name">version_compile_machine</field>
          <field name="Value">i686</field>
          </row>

          <row>
          <field name="Variable_name">version_compile_os</field>
          <field name="Value">suse-linux-gnu</field>
          </row>
          </resultset>

     (See Bug#25946 (http://bugs.mysql.com/25946).)

You can also set the following variables by using `--VAR_NAME=VALUE'.
The `--set-variable' format is deprecated.

   *  `connect_timeout'

     The number of seconds before connection timeout. (Default value is
     `0'.)

   *  `max_allowed_packet'

     The maximum packet length to send to or receive from the server.
     (Default value is 16MB.)

   *  `max_join_size'

     The automatic limit for rows in a join when using
     `--safe-updates'. (Default value is 1,000,000.)

   * `net_buffer_length'

     The buffer size for TCP/IP and socket communication.  (Default
     value is 16KB.)

   *  `select_limit'

     The automatic limit for *Note `SELECT': select. statements when
     using `--safe-updates'. (Default value is 1,000.)

On Unix, the *Note `mysql': mysql. client writes a record of executed
statements to a history file. By default, this file is named
`.mysql_history' and is created in your home directory. To specify a
different file, set the value of the `MYSQL_HISTFILE' environment
variable.

The `.mysql_history' should be protected with a restrictive access mode
because sensitive information might be written to it, such as the text
of SQL statements that contain passwords. See *Note
password-security-user::.

If you do not want to maintain a history file, first remove
`.mysql_history' if it exists, and then use either of the following
techniques:

   * Set the `MYSQL_HISTFILE' variable to `/dev/null'. To cause this
     setting to take effect each time you log in, put the setting in
     one of your shell's startup files.

   * Create `.mysql_history' as a symbolic link to `/dev/null':

          shell> ln -s /dev/null $HOME/.mysql_history

     You need do this only once.


File: manual.info,  Node: mysql-commands,  Next: mysql-server-side-help,  Prev: mysql-command-options,  Up: mysql

4.5.1.2 `mysql' Commands
........................

*Note `mysql': mysql. sends each SQL statement that you issue to the
server to be executed. There is also a set of commands that *Note
`mysql': mysql. itself interprets. For a list of these commands, type
`help' or `\h' at the `mysql>' prompt:

     mysql> help

     List of all MySQL commands:
     Note that all text commands must be first on line and end with ';'
     ?         (\?) Synonym for `help'.
     clear     (\c) Clear command.
     connect   (\r) Reconnect to the server. Optional arguments are db and host.
     delimiter (\d) Set statement delimiter.
     edit      (\e) Edit command with $EDITOR.
     ego       (\G) Send command to mysql server, display result vertically.
     exit      (\q) Exit mysql. Same as quit.
     go        (\g) Send command to mysql server.
     help      (\h) Display this help.
     nopager   (\n) Disable pager, print to stdout.
     notee     (\t) Don't write into outfile.
     pager     (\P) Set PAGER [to_pager]. Print the query results via PAGER.
     print     (\p) Print current command.
     prompt    (\R) Change your mysql prompt.
     quit      (\q) Quit mysql.
     rehash    (\#) Rebuild completion hash.
     source    (\.) Execute an SQL script file. Takes a file name as an argument.
     status    (\s) Get status information from the server.
     system    (\!) Execute a system shell command.
     tee       (\T) Set outfile [to_outfile]. Append everything into given
                    outfile.
     use       (\u) Use another database. Takes database name as argument.
     charset   (\C) Switch to another charset. Might be needed for processing
                    binlog with multi-byte charsets.
     warnings  (\W) Show warnings after every statement.
     nowarning (\w) Don't show warnings after every statement.

     For server side help, type 'help contents'

Each command has both a long and short form. The long form is not case
sensitive; the short form is. The long form can be followed by an
optional semicolon terminator, but the short form should not.

The use of short-form commands within multi-line `/* ...  */' comments
is not supported.

   * *Note `help [ARG]': help, `\h [ARG]', `\? [ARG]', `? [ARG]'

     Displays a help message listing the available *Note `mysql':
     mysql. commands.

     If you provide an argument to the `help' command, *Note `mysql':
     mysql. uses it as a search string to access server-side help from
     the contents of the MySQL Reference Manual. For more information,
     see *Note mysql-server-side-help::.

   * *Note `charset CHARSET_NAME': charset, `\C CHARSET_NAME'

     The `charset' command changes the default character set and issues
     a `SET NAMES' statement. This enables the character set to remain
     synchronized on the client and server if *Note `mysql': mysql. is
     run with auto-reconnect enabled (which is not recommended),
     because the specified character set is used for reconnects.

   * `clear', `\c'

     Clears the current input. Use this if you change your mind about
     executing the statement that you are entering.

   * `connect [DB_NAME HOST_NAME]]', `\r [DB_NAME HOST_NAME]]'

     Reconnects to the server. The optional database name and host name
     arguments may be given to specify the default database or the host
     where the server is running. If omitted, the current values are
     used.

   * `delimiter STR', `\d STR'

     The `delimiter' command changes the string that *Note `mysql':
     mysql. interprets as the separator between SQL statements. The
     default is the semicolon character (``;'').

     The delimiter can be specified as an unquoted or quoted argument.
     Quoting can be done with either single quote (`'') or douple quote
     (`"') characters. To include a quote within a quoted string,
     either quote the string with the other quote character or escape
     the quote with a backslash (``\'') character. Backslash should be
     avoided outside of quoted strings because it is the escape
     character for MySQL. For an unquoted argument, the delmiter is
     read up to the first space or end of line.  For a quoted argument,
     the delimiter is read up to the matching quote on the line.

     When the delimiter recognized by *Note `mysql': mysql. is set to
     something other than the default of ``;'', instances of that
     character are sent to the server without interpretation.  However,
     the server itself still interprets ``;'' as a statement delimiter
     and processes statements accordingly. This behavior on the server
     side comes into play for multiple-statement execution (see *Note
     c-api-multiple-queries::), and for parsing the body of stored
     procedures and functions, triggers, and events (see *Note
     stored-programs-defining::).

   * `edit', `\e'

     Edits the current input statement. *Note `mysql': mysql.  checks
     the values of the `EDITOR' and `VISUAL' environment variables to
     determine which editor to use. The default editor is `vi' if
     neither variable is set.

     The `edit' command works only in Unix.

   * `ego', `\G'

     Sends the current statement to the server to be executed and
     displays the result using vertical format.

   * `exit', `\q'

     Exits *Note `mysql': mysql.

   * `go', `\g'

     Sends the current statement to the server to be executed.

   * `nopager', `\n'

     Disables output paging. See the description for `pager'.

     The `nopager' command works only in Unix.

   * `notee', `\t'

     Disables output copying to the tee file. See the description for
     `tee'.

   * `nowarning', `\w'

     Enables display of warnings after each statement.

   * `pager [COMMAND]', `\P [COMMAND]'

     By using the `--pager' option when you invoke *Note `mysql':
     mysql, it is possible to browse or search query results in
     interactive mode with Unix programs such as `less', `more', or any
     other similar program. If you specify no value for the option,
     *Note `mysql': mysql. checks the value of the `PAGER' environment
     variable and sets the pager to that.

     Output paging can be enabled interactively with the `pager'
     command and disabled with `nopager'. The command takes an optional
     argument; if given, the paging program is set to that. With no
     argument, the pager is set to the pager that was set on the
     command line, or `stdout' if no pager was specified.

     Output paging works only in Unix because it uses the `popen()'
     function, which does not exist on Windows. For Windows, the `tee'
     option can be used instead to save query output, although it is
     not as convenient as `pager' for browsing output in some
     situations.

   * `print', `\p'

     Prints the current input statement without executing it.

   * `prompt [STR]', `\R [STR]'

     Reconfigures the *Note `mysql': mysql. prompt to the given string.
     The special character sequences that can be used in the prompt are
     described later in this section.

     If you specify the `prompt' command with no argument, *Note
     `mysql': mysql. resets the prompt to the default of `mysql>'.

   * `quit', `\q'

     Exits *Note `mysql': mysql.

   * `rehash', `\#'

     Rebuilds the completion hash that enables database, table, and
     column name completion while you are entering statements. (See the
     description for the `--auto-rehash' option.)

   * `source FILE_NAME', `\.  FILE_NAME'

     Reads the named file and executes the statements contained
     therein. On Windows, you can specify path name separators as `/'
     or `\\'.

   * `status', `\s'

     The `status' command provides some information about the
     connection and the server you are using. If you are running in
     `--safe-updates' mode, `status' also prints the values for the
     *Note `mysql': mysql. variables that affect your queries.

   * `system COMMAND', `\!  COMMAND'

     Executes the given command using your default command interpreter.

     The `system' command works only in Unix.

   * `tee [FILE_NAME]', `\T [FILE_NAME]'

     By using the `--tee' option when you invoke *Note `mysql': mysql,
     you can log statements and their output. All the data displayed on
     the screen is appended into a given file. This can be very useful
     for debugging purposes also. *Note `mysql': mysql. flushes results
     to the file after each statement, just before it prints its next
     prompt.

     You can enable this feature interactively with the `tee' command.
     Without a parameter, the previous file is used. The `tee' file can
     be disabled with the `notee' command.  Executing `tee' again
     re-enables logging.

   * *Note `use DB_NAME': use, `\u DB_NAME'

     Uses DB_NAME as the default database.

   * `warnings', `\W'

     Enables display of warnings after each statement (if there are
     any).

Here are a few tips about the `pager' command:

   * You can use it to write to a file and the results go only to the
     file:

          mysql> pager cat > /tmp/log.txt

     You can also pass any options for the program that you want to use
     as your pager:

          mysql> pager less -n -i -S

   * In the preceding example, note the `-S' option. You may find it
     very useful for browsing wide query results. Sometimes a very wide
     result set is difficult to read on the screen. The `-S' option to
     `less' can make the result set much more readable because you can
     scroll it horizontally using the left-arrow and right-arrow keys.
     You can also use `-S' interactively within `less' to switch the
     horizontal-browse mode on and off. For more information, read the
     `less' manual page:

          shell> man less

   * The `-F' and `-X' options may be used with `less' to cause it to
     exit if output fits on one screen, which is convenient when no
     scrolling is necessary:

          mysql> pager less -n -i -S -F -X

   * You can specify very complex pager commands for handling query
     output:

          mysql> pager cat | tee /dr1/tmp/res.txt \
                    | tee /dr2/tmp/res2.txt | less -n -i -S

     In this example, the command would send query results to two files
     in two different directories on two different file systems mounted
     on `/dr1' and `/dr2', yet still display the results onscreen via
     `less'.

You can also combine the `tee' and `pager' functions. Have a `tee' file
enabled and `pager' set to `less', and you are able to browse the
results using the `less' program and still have everything appended
into a file the same time. The difference between the Unix `tee' used
with the `pager' command and the *Note `mysql': mysql. built-in `tee'
command is that the built-in `tee' works even if you do not have the
Unix `tee' available. The built-in `tee' also logs everything that is
printed on the screen, whereas the Unix `tee' used with `pager' does
not log quite that much.  Additionally, `tee' file logging can be turned
on and off interactively from within *Note `mysql': mysql.  This is
useful when you want to log some queries to a file, but not others.

The `prompt' command reconfigures the default `mysql>' prompt. The
string for defining the prompt can contain the following special
sequences.

*Option*    *Description*
`\c'        A counter that increments for each statement you issue
`\D'        The full current date
`\d'        The default database
`\h'        The server host
`\l'        The current delimiter
`\m'        Minutes of the current time
`\n'        A newline character
`\O'        The current month in three-letter format (Jan, Feb,
            ...)
`\o'        The current month in numeric format
`\P'        am/pm
`\p'        The current TCP/IP port or socket file
`\R'        The current time, in 24-hour military time (0-23)
`\r'        The current time, standard 12-hour time (1-12)
`\S'        Semicolon
`\s'        Seconds of the current time
`\t'        A tab character
`\U'        Your full `USER_NAME@HOST_NAME' account name
`\u'        Your user name
`\v'        The server version
`\w'        The current day of the week in three-letter format
            (Mon, Tue, ...)
`\Y'        The current year, four digits
`\y'        The current year, two digits
`\_'        A space
`\ '        A space (a space follows the backslash)
`\''        Single quote
`\"'        Double quote
`\\'        A literal ``\'' backslash character
`\X'        X, for any `X' not listed above

You can set the prompt in several ways:

   * _Use an environment variable._ You can set the `MYSQL_PS1'
     environment variable to a prompt string. For example:

          shell> export MYSQL_PS1="(\u@\h) [\d]> "

   * _Use a command-line option._ You can set the `--prompt' option on
     the command line to *Note `mysql': mysql. For example:

          shell> mysql --prompt="(\u@\h) [\d]> "
          (user@host) [database]>

   * _Use an option file._ You can set the `prompt' option in the
     `[mysql]' group of any MySQL option file, such as `/etc/my.cnf' or
     the `.my.cnf' file in your home directory.  For example:

          [mysql]
          prompt=(\\u@\\h) [\\d]>\\_

     In this example, note that the backslashes are doubled. If you set
     the prompt using the `prompt' option in an option file, it is
     advisable to double the backslashes when using the special prompt
     options. There is some overlap in the set of allowable prompt
     options and the set of special escape sequences that are
     recognized in option files. (These sequences are listed in *Note
     option-files::.) The overlap may cause you problems if you use
     single backslashes. For example, `\s' is interpreted as a space
     rather than as the current seconds value. The following example
     shows how to define a prompt within an option file to include the
     current time in `HH:MM:SS>' format:

          [mysql]
          prompt="\\r:\\m:\\s> "

   * _Set the prompt interactively._ You can change your prompt
     interactively by using the `prompt' (or `\R') command. For example:

          mysql> prompt (\u@\h) [\d]>\_
          PROMPT set to '(\u@\h) [\d]>\_'
          (USER@HOST) [DATABASE]>
          (USER@HOST) [DATABASE]> prompt
          Returning to default PROMPT of mysql>
          mysql>


File: manual.info,  Node: mysql-server-side-help,  Next: batch-commands,  Prev: mysql-commands,  Up: mysql

4.5.1.3 `mysql' Server-Side Help
................................

     mysql> help SEARCH_STRING

If you provide an argument to the `help' command, *Note `mysql': mysql.
uses it as a search string to access server-side help from the contents
of the MySQL Reference Manual. The proper operation of this command
requires that the help tables in the `mysql' database be initialized
with help topic information (see *Note server-side-help-support::).

If there is no match for the search string, the search fails:

     mysql> help me

     Nothing found
     Please try to run 'help contents' for a list of all accessible topics

Use *Note `help contents': help. to see a list of the help categories:

     mysql> help contents
     You asked for help about help category: "Contents"
     For more information, type 'help <item>', where <item> is one of the
     following categories:
        Account Management
        Administration
        Data Definition
        Data Manipulation
        Data Types
        Functions
        Functions and Modifiers for Use with GROUP BY
        Geographic Features
        Language Structure
        Plugins
        Storage Engines
        Stored Routines
        Table Maintenance
        Transactions
        Triggers

If the search string matches multiple items, *Note `mysql': mysql.
shows a list of matching topics:

     mysql> help logs
     Many help items for your request exist.
     To make a more specific request, please type 'help <item>',
     where <item> is one of the following topics:
        SHOW
        SHOW BINARY LOGS
        SHOW ENGINE
        SHOW LOGS

Use a topic as the search string to see the help entry for that topic:

     mysql> help show binary logs
     Name: 'SHOW BINARY LOGS'
     Description:
     Syntax:
     SHOW BINARY LOGS
     SHOW MASTER LOGS

     Lists the binary log files on the server. This statement is used as
     part of the procedure described in [purge-binary-logs], that shows how
     to determine which logs can be purged.

     mysql> SHOW BINARY LOGS;
     +---------------+-----------+
     | Log_name      | File_size |
     +---------------+-----------+
     | binlog.000015 |    724935 |
     | binlog.000016 |    733481 |
     +---------------+-----------+


File: manual.info,  Node: batch-commands,  Next: mysql-tips,  Prev: mysql-server-side-help,  Up: mysql

4.5.1.4 Executing SQL Statements from a Text File
.................................................

The *Note `mysql': mysql. client typically is used interactively, like
this:

     shell> mysql DB_NAME

However, it is also possible to put your SQL statements in a file and
then tell *Note `mysql': mysql. to read its input from that file. To do
so, create a text file TEXT_FILE that contains the statements you wish
to execute. Then invoke *Note `mysql': mysql. as shown here:

     shell> mysql DB_NAME < TEXT_FILE

If you place a `USE DB_NAME' statement as the first statement in the
file, it is unnecessary to specify the database name on the command
line:

     shell> mysql < text_file

If you are already running *Note `mysql': mysql, you can execute an SQL
script file using the `source' command or `\.' command:

     mysql> source FILE_NAME
     mysql> \. FILE_NAME

Sometimes you may want your script to display progress information to
the user. For this you can insert statements like this:

     SELECT '<info_to_display>' AS ' ';

The statement shown outputs `<info_to_display>'.

As of MySQL 6.0.4, *Note `mysql': mysql. ignores Unicode byte order
mark (BOM) characters at the beginning of input files.  Previously, it
read them and sent them to the server, resulting in a syntax error.
Presence of a BOM does not cause *Note `mysql': mysql. to change its
default character set. To do that, invoke *Note `mysql': mysql. with an
option such as `--default-character-set=utf8'.

For more information about batch mode, see *Note batch-mode::.


File: manual.info,  Node: mysql-tips,  Prev: batch-commands,  Up: mysql

4.5.1.5 `mysql' Tips
....................

* Menu:

* vertical-query-results::       Displaying Query Results Vertically
* safe-updates::                 Using the `--safe-updates' Option
* mysql-reconnect::              Disabling `mysql' Auto-Reconnect

This section describes some techniques that can help you use *Note
`mysql': mysql. more effectively.


File: manual.info,  Node: vertical-query-results,  Next: safe-updates,  Prev: mysql-tips,  Up: mysql-tips

4.5.1.6 Displaying Query Results Vertically
...........................................

Some query results are much more readable when displayed vertically,
instead of in the usual horizontal table format.  Queries can be
displayed vertically by terminating the query with \G instead of a
semicolon. For example, longer text values that include newlines often
are much easier to read with vertical output:

     mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G
     *************************** 1. row ***************************
       msg_nro: 3068
          date: 2000-03-01 23:29:50
     time_zone: +0200
     mail_from: Monty
         reply: monty@no.spam.com
       mail_to: "Thimble Smith" <tim@no.spam.com>
           sbj: UTF-8
           txt: >>>>> "Thimble" == Thimble Smith writes:

     Thimble> Hi.  I think this is a good idea.  Is anyone familiar
     Thimble> with UTF-8 or Unicode? Otherwise, I'll put this on my
     Thimble> TODO list and see what happens.

     Yes, please do that.

     Regards,
     Monty
          file: inbox-jani-1
          hash: 190402944
     1 row in set (0.09 sec)


File: manual.info,  Node: safe-updates,  Next: mysql-reconnect,  Prev: vertical-query-results,  Up: mysql-tips

4.5.1.7 Using the `--safe-updates' Option
.........................................

For beginners, a useful startup option is `--safe-updates' (or
`--i-am-a-dummy', which has the same effect). It is helpful for cases
when you might have issued a `DELETE FROM TBL_NAME' statement but
forgotten the `WHERE' clause. Normally, such a statement deletes all
rows from the table. With `--safe-updates', you can delete rows only by
specifying the key values that identify them.  This helps prevent
accidents.

When you use the `--safe-updates' option, *Note `mysql': mysql. issues
the following statement when it connects to the MySQL server:

     SET sql_safe_updates=1, sql_select_limit=1000, sql_max_join_size=1000000;

See *Note server-session-variables::.

The *Note `SET': set-option.  statement has the following effects:

   * You are not allowed to execute an *Note `UPDATE': update. or *Note
     `DELETE': delete. statement unless you specify a key constraint in
     the `WHERE' clause or provide a `LIMIT' clause (or both). For
     example:

          UPDATE TBL_NAME SET NOT_KEY_COLUMN=VAL WHERE KEY_COLUMN=VAL;

          UPDATE TBL_NAME SET NOT_KEY_COLUMN=VAL LIMIT 1;

   * The server limits all large *Note `SELECT': select. results to
     1,000 rows unless the statement includes a `LIMIT' clause.

   * The server aborts multiple-table *Note `SELECT': select.
     statements that probably need to examine more than 1,000,000 row
     combinations.

To specify limits different from 1,000 and 1,000,000, you can override
the defaults by using the `--select_limit' and `--max_join_size'
options:

     shell> mysql --safe-updates --select_limit=500 --max_join_size=10000


File: manual.info,  Node: mysql-reconnect,  Prev: safe-updates,  Up: mysql-tips

4.5.1.8 Disabling `mysql' Auto-Reconnect
........................................

If the *Note `mysql': mysql. client loses its connection to the server
while sending a statement, it immediately and automatically tries to
reconnect once to the server and send the statement again. However,
even if *Note `mysql': mysql.  succeeds in reconnecting, your first
connection has ended and all your previous session objects and settings
are lost: temporary tables, the autocommit mode, and user-defined and
session variables. Also, any current transaction rolls back.  This
behavior may be dangerous for you, as in the following example where
the server was shut down and restarted between the first and second
statements without you knowing it:

     mysql> SET @a=1;
     Query OK, 0 rows affected (0.05 sec)

     mysql> INSERT INTO t VALUES(@a);
     ERROR 2006: MySQL server has gone away
     No connection. Trying to reconnect...
     Connection id:    1
     Current database: test

     Query OK, 1 row affected (1.30 sec)

     mysql> SELECT * FROM t;
     +------+
     | a    |
     +------+
     | NULL |
     +------+
     1 row in set (0.05 sec)

The `@a' user variable has been lost with the connection, and after the
reconnection it is undefined. If it is important to have *Note `mysql':
mysql. terminate with an error if the connection has been lost, you can
start the *Note `mysql': mysql. client with the `--skip-reconnect'
option.

For more information about auto-reconnect and its effect on state
information when a reconnection occurs, see *Note auto-reconnect::.


File: manual.info,  Node: mysqladmin,  Next: mysqlcheck,  Prev: mysql,  Up: programs-client

4.5.2 `mysqladmin' -- Client for Administering a MySQL Server
-------------------------------------------------------------

*Note `mysqladmin': mysqladmin. is a client for performing
administrative operations. You can use it to check the server's
configuration and current status, to create and drop databases, and
more.

Invoke *Note `mysqladmin': mysqladmin. like this:

     shell> mysqladmin [OPTIONS] COMMAND [COMMAND-ARG] [COMMAND [COMMAND-ARG]] ...

*Note `mysqladmin': mysqladmin. supports the commands described in the
following list. Some of the commands take an argument following the
command name.

   *  `create DB_NAME'

     Create a new database named DB_NAME.

   *  `debug'

     Tell the server to write debug information to the error log.

     This includes information about the Event Scheduler. See *Note
     events-status-info::.

   *  `drop DB_NAME'

     Delete the database named DB_NAME and all its tables.

   *  `extended-status'

     Display the server status variables and their values.

     MySQL Enterprise

     For expert advice on using server status variables, subscribe to
     the MySQL Enterprise Monitor. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `flush-hosts'

     Flush all information in the host cache.

   *  `flush-logs'

     Flush all logs.

   *  `flush-privileges'

     Reload the grant tables (same as `reload').

   *  `flush-status'

     Clear status variables.

   *  `flush-tables'

     Flush all tables.

   *  `flush-threads'

     Flush the thread cache.

   *  `kill ID,ID,...'

     Kill server threads. If multiple thread ID values are given, there
     must be no spaces in the list.

   *  `old-password NEW-PASSWORD'

     This is like the `password' command but stores the password using
     the old (pre-4.1) password-hashing format. (See *Note
     password-hashing::.)

     MySQL Enterprise

     For expert advice on the security implications of using the
     `old-password' command, subscribe to the MySQL Enterprise Monitor.
     For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `password NEW-PASSWORD'

     Set a new password. This changes the password to NEW-PASSWORD for
     the account that you use with *Note `mysqladmin': mysqladmin. for
     connecting to the server. Thus, the next time you invoke *Note
     `mysqladmin': mysqladmin. (or any other client program) using the
     same account, you will need to specify the new password.

     If the NEW-PASSWORD value contains spaces or other characters that
     are special to your command interpreter, you need to enclose it
     within quotes.  On Windows, be sure to use double quotes rather
     than single quotes; single quotes are not stripped from the
     password, but rather are interpreted as part of the password. For
     example:

          shell> mysqladmin password "my new password"

     *Caution*:

     Do not use this command used if the server was started with the
     `--skip-grant-tables' option.  No password change will be applied.
     This is true even if you precede the `password' command with
     `flush-privileges' on the same command line to re-enable the grant
     tables because the flush operation occurs after you connect.
     However, you can use *Note `mysqladmin flush-privileges':
     mysqladmin. to re-enable the grant table and then use a separate
     *Note `mysqladmin password': mysqladmin. command to change the
     password.

   *  `ping'

     Check whether the server is alive. The return status from *Note
     `mysqladmin': mysqladmin. is 0 if the server is running, 1 if it
     is not. This is 0 even in case of an error such as `Access
     denied', because this means that the server is running but refused
     the connection, which is different from the server not running.

   *  `processlist'

     Show a list of active server threads. This is like the output of
     the *Note `SHOW PROCESSLIST': show-processlist. statement. If the
     `--verbose' option is given, the output is like that of *Note
     `SHOW FULL PROCESSLIST': show-processlist. (See *Note
     show-processlist::.)

   *  `reload'

     Reload the grant tables.

   *  `refresh'

     Flush all tables and close and open log files.

   *  `shutdown'

     Stop the server.

   *  `start-slave'

     Start replication on a slave server.

   *  `status'

     Display a short server status message.

   *  `stop-slave'

     Stop replication on a slave server.

   *  `variables'

     Display the server system variables and their values.

     MySQL Enterprise

     For expert advice on using server system variables, subscribe to
     the MySQL Enterprise Monitor. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `version'

     Display version information from the server.

All commands can be shortened to any unique prefix. For example:

     shell> mysqladmin proc stat
     +----+-------+-----------+----+---------+------+-------+------------------+
     | Id | User  | Host      | db | Command | Time | State | Info             |
     +----+-------+-----------+----+---------+------+-------+------------------+
     | 51 | monty | localhost |    | Query   | 0    |       | show processlist |
     +----+-------+-----------+----+---------+------+-------+------------------+
     Uptime: 1473624  Threads: 1  Questions: 39487
     Slow queries: 0  Opens: 541  Flush tables: 1
     Open tables: 19  Queries per second avg: 0.0268

The *Note `mysqladmin status': mysqladmin. command result displays the
following values:

   * `Uptime'

     The number of seconds the MySQL server has been running.

   * `Threads'

     The number of active threads (clients).

   * `Questions'

     The number of questions (queries) from clients since the server
     was started.

   * `Slow queries'

     The number of queries that have taken more than `long_query_time'
     seconds.  See *Note slow-query-log::.

   * `Opens'

     The number of tables the server has opened.

   * `Flush tables'

     The number of `flush-*', `refresh', and `reload' commands the
     server has executed.

   * `Open tables'

     The number of tables that currently are open.

   * `Memory in use'

     The amount of memory allocated directly by *Note `mysqld': mysqld.
     This value is displayed only when MySQL has been compiled with
     `--with-debug=full'.

   * `Maximum memory used'

     The maximum amount of memory allocated directly by *Note `mysqld':
     mysqld. This value is displayed only when MySQL has been compiled
     with `--with-debug=full'.

If you execute *Note `mysqladmin shutdown': mysqladmin. when connecting
to a local server using a Unix socket file, *Note `mysqladmin':
mysqladmin. waits until the server's process ID file has been removed,
to ensure that the server has stopped properly.

*`mysqladmin' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-compress   compress    Compress all information sent                
                        between the client and the server            
-connect_timeout=secondsconnect_timeoutThe number of seconds before                 
                        connection timeout                           
-count=#    count       The number of iterations to make             
                        for repeated command execution               
-debug[=debug_options]debug       Write a debugging log                        
-debug-checkdebug-check Print debugging information when             
                        the program exits                            
-debug-info debug-info  Print debugging information, memory          
                        and CPU statistics when the                  
                        program exits                                
-default-character-set=charset_namedefault-character-setUse charset_name as the default              
                        character set                                
-force      force       Continue even if an SQL error occurs         
-help                   Display help message and exit                
-host=host_namehost        Connect to the MySQL server on the           
                        given host                                   
-no-beep    no-beep     Do not beep when errors occur                
-password[=password]password    The password to use when connecting          
                        to the server                                
-pipe                   On Windows, connect to server via a          
                        named pipe                                   
-port=port_numport        The TCP/IP port number to use for            
                        the connection                               
-protocol=typeprotocol    The connection protocol to use               
-relative   relative    Show the difference between the              
                        current and previous values when             
                        used with the -sleep option                  
-shutdown_timeout=secondsshutdown_timeoutThe maximum number of seconds to             
                        wait for server shutdown                     
-silent     silent      Silent mode                                  
-sleep=delaysleep       Execute commands repeatedly,                 
                        sleeping for delay seconds in                
                        between                                      
-socket=pathsocket      For connections to localhost                 
-ssl-ca=file_namessl-ca      The path to a file that contains a           
                        list of trusted SSL CAs                      
-ssl-capath=directory_namessl-capath  The path to a directory that                 
                        contains trusted SSL CA                      
                        certificates  in PEM format                  
-ssl-cert=file_namessl-cert    The name of the SSL certificate              
                        file to use for establishing a               
                        secure connection                            
-ssl-cipher=cipher_listssl-cipher  A list of allowable ciphers to use           
                        for SSL encryption                           
-ssl-key=file_namessl-key     The name of the SSL key file to use          
                        for establishing a secure                    
                        connection                                   
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in            
                        its certificate is verified                  
                        against the host name used when              
                        connecting to the server                     
-user=user_name,user        The MySQL user name to use when              
                        connecting to the server                     
-verbose                Verbose mode                                 
-version                Display version information and exit         
-vertical   vertical    Print query output rows vertically           
                        (one line per column value)                  
-wait       wait        If the connection cannot be                  
                        established, wait and retry instead          
                        of  aborting                                 

*Note `mysqladmin': mysqladmin. supports the options in the following
list. It also reads option files and supports the options for
processing them described at *Note option-file-options::.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--count=N', `-c N'

     The number of iterations to make for repeated command execution if
     the `--sleep' option is given.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is
     `'d:t:o,/tmp/mysqladmin.trace''.

   *  `--debug-check'

     Print some debugging information when the program exits.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.

   *  `--force', `-f'

     Do not ask for confirmation for the `drop DB_NAME' command. With
     multiple commands, continue even if an error occurs.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--no-beep', `-b'

     Suppress the warning beep that is emitted by default for errors
     such as a failure to connect to the server.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--relative', `-r'

     Show the difference between the current and previous values when
     used with the `--sleep' option.  Currently, this option works only
     with the `extended-status' command.

   *  `--silent', `-s'

     Exit silently if a connection to the server cannot be established.

   *  `--sleep=DELAY', `-i DELAY'

     Execute commands repeatedly, sleeping for DELAY seconds in
     between. The `--count' option determines the number of iterations.
     If `--count' is not given, *Note `mysqladmin': mysqladmin.
     executes commands indefinitely until interrupted.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL user name to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.

   *  `--version', `-V'

     Display version information and exit.

   *  `--vertical', `-E'

     Print output vertically. This is similar to `--relative', but
     prints output vertically.

   *  `--wait[=COUNT]', `-w[COUNT]'

     If the connection cannot be established, wait and retry instead of
     aborting. If a COUNT value is given, it indicates the number of
     times to retry.  The default is one time.

You can also set the following variables by using `--VAR_NAME=VALUE'
The `--set-variable' format is deprecated.  syntax:

   *  `connect_timeout'

     The maximum number of seconds before connection timeout. The
     default value is 43200 (12 hours).

   *  `shutdown_timeout'

     The maximum number of seconds to wait for server shutdown.  The
     default value is 3600 (1 hour).


File: manual.info,  Node: mysqlcheck,  Next: mysqldump,  Prev: mysqladmin,  Up: programs-client

4.5.3 `mysqlcheck' -- A Table Maintenance and Repair Program
------------------------------------------------------------

The *Note `mysqlcheck': mysqlcheck. client checks, repairs, optimizes,
and analyzes tables.

*Note `mysqlcheck': mysqlcheck. is similar in function to *Note
`myisamchk': myisamchk, but works differently. The main operational
difference is that *Note `mysqlcheck': mysqlcheck.  must be used when
the *Note `mysqld': mysqld. server is running, whereas *Note
`myisamchk': myisamchk. should be used when it is not. The benefit of
using *Note `mysqlcheck': mysqlcheck. is that you do not have to stop
the server to check or repair your tables.

*Note `mysqlcheck': mysqlcheck. uses the SQL statements *Note `CHECK
TABLE': check-table, *Note `REPAIR TABLE': repair-table, *Note `ANALYZE
TABLE': analyze-table, and *Note `OPTIMIZE TABLE': optimize-table. in a
convenient way for the user. It determines which statements to use for
the operation you want to perform, and then sends the statements to the
server to be executed. For details about which storage engines each
statement works with, see the descriptions for those statements in
*Note sql-syntax::.

The `MyISAM' storage engine supports all four statements, so *Note
`mysqlcheck': mysqlcheck. can be used to perform all four operations on
`MyISAM' tables.  Other storage engines do not necessarily support all
operations.  In such cases, an error message is displayed. For example,
if `test.t' is a `MEMORY' table, an attempt to check it produces this
result:

     shell> mysqlcheck test t
     test.t
     note     : The storage engine for the table doesn't support check

The use of *Note `mysqlcheck': mysqlcheck. with partitioned tables is
not supported before MySQL 6.0.6.

*Caution*:

It is best to make a backup of a table before performing a table repair
operation; under some circumstances the operation might cause data
loss. Possible causes include but are not limited to file system errors.

There are three general ways to invoke *Note `mysqlcheck': mysqlcheck.:

     shell> mysqlcheck [OPTIONS] DB_NAME [TABLES]
     shell> mysqlcheck [OPTIONS] --databases DB_NAME1 [DB_NAME2 DB_NAME3...]
     shell> mysqlcheck [OPTIONS] --all-databases

If you do not name any tables following DB_NAME or if you use the
`--databases' or `--all-databases' option, entire databases are checked.

*Note `mysqlcheck': mysqlcheck. has a special feature compared to other
client programs. The default behavior of checking tables (`--check')
can be changed by renaming the binary. If you want to have a tool that
repairs tables by default, you should just make a copy of *Note
`mysqlcheck': mysqlcheck. named `mysqlrepair', or make a symbolic link
to *Note `mysqlcheck': mysqlcheck. named `mysqlrepair'. If you invoke
`mysqlrepair', it repairs tables.

The following names can be used to change *Note `mysqlcheck':
mysqlcheck. default behavior.

`mysqlrepair'      The default option is `--repair'
`mysqlanalyze'     The default option is `--analyze'
`mysqloptimize'    The default option is `--optimize'

*`mysqlcheck' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-all-databasesall-databasesCheck all tables in all databases            
-all-in-1   all-in-1    Execute a single statement for each          
                        database that names all the  tables          
                        from that database                           
-analyze    analyze     Analyze the tables                           
-auto-repairauto-repair If a checked table is corrupted,             
                        automatically fix it                         
-bind-address=host_name            Determine which client network               
                        interface (IP address or host name)          
                        to use when connecting to the                
                        MySQL Server                                 
-character-sets-dir=pathcharacter-sets-dirThe directory where character sets           
                        are installed                                
-check      check       Check the tables for errors                  
-check-only-changedcheck-only-changedCheck only tables that have changed          
                        since the last check                         
-check-upgradecheck-upgradeInvoke CHECK TABLE with the FOR              
                        UPGRADE option                               
-compress   compress    Compress all information sent                
                        between the client and the server            
-databases  databases   Process all tables in the named              
                        databases                                    
-debug[=debug_options]debug       Write a debugging log                        
-debug-checkdebug-check Print debugging information when             
                        the program exits                            
-debug-info debug-info  Print debugging information, memory          
                        and CPU statistics when the                  
                        program exits                                
-default-character-set=charset_namedefault-character-setUse charset_name as the default              
                        character set                                
-extended   extended    Check and repair tables                      
-fast       fast        Check only tables that have not              
                        been closed properly                         
-fix-db-namesfix-db-namesConvert database names to 5.1 format         
-fix-table-namesfix-table-namesConvert table names to 5.1 format            
-force      force       Continue even if an SQL error occurs         
-help                   Display help message and exit                
-host=host_namehost        Connect to the MySQL server on the           
                        given host                                   
-medium-checkmedium-checkDo a check that is faster than an            
                        -extended operation                          
-optimize   optimize    Optimize the tables                          
-password[=password]password    The password to use when connecting          
                        to the server                                
-pipe                   On Windows, connect to server via a          
                        named pipe                                   
-port=port_numport        The TCP/IP port number to use for            
                        the connection                               
-protocol=typeprotocol    The connection protocol to use               
-quick      quick       The fastest method of checking               
-repair     repair      Perform a repair that can fix                
                        almost anything except unique keys           
                        that are not unique                          
-silent     silent      Silent mode                                  
-socket=pathsocket      For connections to localhost                 
-ssl-ca=file_namessl-ca      The path to a file that contains a           
                        list of trusted SSL CAs                      
-ssl-capath=directory_namessl-capath  The path to a directory that                 
                        contains trusted SSL CA                      
                        certificates  in PEM format                  
-ssl-cert=file_namessl-cert    The name of the SSL certificate              
                        file to use for establishing a               
                        secure connection                            
-ssl-cipher=cipher_listssl-cipher  A list of allowable ciphers to use           
                        for SSL encryption                           
-ssl-key=file_namessl-key     The name of the SSL key file to use          
                        for establishing a secure                    
                        connection                                   
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in            
                        its certificate is verified                  
                        against the host name used when              
                        connecting to the server                     
-tables     tables      Overrides the -databases or -B               
                        option                                       
-use-frm    use-frm     For repair operations on MyISAM              
                        tables                                       
-user=user_name,user        The MySQL user name to use when              
                        connecting to the server                     
-verbose                Verbose mode                                 
-version                Display version information and exit         
-write-binlogwrite-binlogLog ANALYZE, OPTIMIZE, REPAIR                
                        statements to binary log.                    
                        -skip-write-binlog adds                      
                        NO_WRITE_TO_BINLOG to these                  
                        statements.                                  

*Note `mysqlcheck': mysqlcheck. supports the options in the following
list. It also reads option files and supports the options for
processing them described at *Note option-file-options::.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--all-databases', `-A'

     Check all tables in all databases. This is the same as using the
     `--databases' option and naming all the databases on the command
     line.

   *  `--all-in-1', `-1'

     Instead of issuing a statement for each table, execute a single
     statement for each database that names all the tables from that
     database to be processed.

   *  `--analyze', `-a'

     Analyze the tables.

     MySQL Enterprise

     For expert advice on optimizing tables, subscribe to the MySQL
     Enterprise Monitor. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--auto-repair'

     If a checked table is corrupted, automatically fix it. Any
     necessary repairs are done after all tables have been checked.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--check', `-c'

     Check the tables for errors. This is the default operation.

   *  `--check-only-changed', `-C'

     Check only tables that have changed since the last check or that
     have not been closed properly.

   *  `--check-upgrade', `-g'

     Invoke *Note `CHECK TABLE': check-table. with the `FOR UPGRADE'
     option to check tables for incompatibilities with the current
     version of the server.  This option automatically enables the
     `--fix-db-names' and `--fix-table-names' options.

   *  `--compress'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--databases', `-B'

     Process all tables in the named databases. Normally, *Note
     `mysqlcheck': mysqlcheck. treats the first name argument on the
     command line as a database name and following names as table
     names. With this option, it treats all name arguments as database
     names.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is `'d:t:o''.

   *  `--debug-check'

     Print some debugging information when the program exits.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.

   *  `--extended', `-e'

     If you are using this option to check tables, it ensures that they
     are 100% consistent but takes a long time.

     If you are using this option to repair tables, it runs an extended
     repair that may not only take a long time to execute, but may
     produce a lot of garbage rows also!

   *  `--fast', `-F'

     Check only tables that have not been closed properly.

   *  `--fix-db-names'

     Convert database names to 5.1 format. Only database names that
     contain special characters are affected.

   *  `--fix-table-names'

     Convert table names to 5.1 format. Only table names that contain
     special characters are affected. As of MySQL 6.0.5, this option
     also applies to views.

   *  `--force', `-f'

     Continue even if an SQL error occurs.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--medium-check', `-m'

     Do a check that is faster than an `--extended' operation.  This
     finds only 99.99% of all errors, which should be good enough in
     most cases.

   *  `--optimize', `-o'

     Optimize the tables.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--quick', `-q'

     If you are using this option to check tables, it prevents the
     check from scanning the rows to check for incorrect links. This is
     the fastest check method.

     If you are using this option to repair tables, it tries to repair
     only the index tree. This is the fastest repair method.

   *  `--repair', `-r'

     Perform a repair that can fix almost anything except unique keys
     that are not unique.

   *  `--silent', `-s'

     Silent mode. Print only error messages.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--tables'

     Overrides the `--databases' or `-B' option. All name arguments
     following the option are regarded as table names.

   *  `--use-frm'

     For repair operations on `MyISAM' tables, get the table structure
     from the `.frm' file so that the table can be repaired even if the
     `.MYI' header is corrupted.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL user name to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Print information about the various stages of
     program operation.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: mysqldump,  Next: mysqlimport,  Prev: mysqlcheck,  Up: programs-client

4.5.4 `mysqldump' -- A Database Backup Program
----------------------------------------------

The *Note `mysqldump': mysqldump. client is a backup program originally
written by Igor Romanenko. It can be used to dump a database or a
collection of databases for backup or transfer to another SQL server
(not necessarily a MySQL server). The dump typically contains SQL
statements to create the table, populate it, or both. However, *Note
`mysqldump': mysqldump. can also be used to generate files in CSV,
other delimited text, or XML format.

If you are doing a backup on the server and your tables all are
`MyISAM' tables, consider using the *Note `mysqlhotcopy': mysqlhotcopy.
instead because it can accomplish faster backups and faster restores.
See *Note mysqlhotcopy::.

There are three general ways to invoke *Note `mysqldump': mysqldump.:

     shell> mysqldump [OPTIONS] DB_NAME [TABLES]
     shell> mysqldump [OPTIONS] --databases DB_NAME1 [DB_NAME2 DB_NAME3...]
     shell> mysqldump [OPTIONS] --all-databases

If you do not name any tables following DB_NAME or if you use the
`--databases' or `--all-databases' option, entire databases are dumped.

*Note `mysqldump': mysqldump. does not dump the `INFORMATION_SCHEMA'
database. If you name that database explicitly on the command line,
*Note `mysqldump': mysqldump. silently ignores it.

To get a list of the options your version of *Note `mysqldump':
mysqldump. supports, execute *Note `mysqldump --help': mysqldump.

Some *Note `mysqldump': mysqldump. options are shorthand for groups of
other options. `--opt' and `--compact' fall into this category. For
example, use of `--opt' is the same as specifying `--add-drop-table'
`--add-locks' `--create-options' `--disable-keys' `--extended-insert'
`--lock-tables' `--quick' `--set-charset'. Note that all of the options
that `--opt' stands for also are on by default because `--opt' is on by
default.

To reverse the effect of a group option, uses its `--skip-XXX' form
(`--skip-opt' or `--skip-compact').  It is also possible to select only
part of the effect of a group option by following it with options that
enable or disable specific features. Here are some examples:

   * To select the effect of `--opt' except for some features, use the
     `--skip' option for each feature. For example, to disable extended
     inserts and memory buffering, use `--opt' `--skip-extended-insert'
     `--skip-quick'.  (As of MySQL 6.0, `--skip-extended-insert'
     `--skip-quick' is sufficient because `--opt' is on by default.)

   * To reverse `--opt' for all features except index disabling and
     table locking, use `--skip-opt' `--disable-keys' `--lock-tables'.

When you selectively enable or disable the effect of a group option,
order is important because options are processed first to last. For
example, `--disable-keys' `--lock-tables' `--skip-opt' would not have
the intended effect; it is the same as `--skip-opt' by itself.

*Note `mysqldump': mysqldump. can retrieve and dump table contents row
by row, or it can retrieve the entire content from a table and buffer
it in memory before dumping it. Buffering in memory can be a problem if
you are dumping large tables. To dump tables row by row, use the
`--quick' option (or `--opt', which enables `--quick'). The `--opt'
option (and hence `--quick') is enabled by default in MySQL 6.0; to
enable memory buffering, use `--skip-quick'.

If you are using a recent version of *Note `mysqldump': mysqldump. to
generate a dump to be reloaded into a very old MySQL server, you should
not use the `--opt' or `--extended-insert' option. Use `--skip-opt'
instead.

*`mysqldump' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-add-drop-databaseadd-drop-databaseAdd a DROP DATABASE statement                
                        before each CREATE DATABASE                  
                        statement                                    
-add-drop-tableadd-drop-tableAdd a DROP TABLE statement before            
                        each CREATE TABLE statement                  
-add-locks  add-locks   Surround each table dump with LOCK           
                        TABLES and UNLOCK TABLES  statements         
-all-databasesall-databasesDump all tables in all databases             
-allow-keywordsallow-keywordsAllow creation of column names that          
                        are keywords                                 
-apply-slave-statementsapply-slave-statementsInclude STOP SLAVE prior to CHANGE   6.0.4   
                        MASTER statement and START  SLAVE            
                        at end of output                             
-comments   comments    Add comments to the dump file                
-compact    compact     Produce less verbose output                  
-compatible=name[,name,...]compatible  Produce output that is more                  
                        compatible with other database               
                        systems  or with older MySQL servers         
-complete-insertcomplete-insertUse complete INSERT statements that          
                        include column names                         
-create-optionscreate-optionsInclude all MySQL-specific table             
                        options in the CREATE TABLE                  
                        statements                                   
-databases  databases   Dump several databases                       
-debug[=debug_options]debug       Write a debugging log                        
-debug-checkdebug-check Print debugging information when             
                        the program exits                            
-debug-info debug-info  Print debugging information, memory          
                        and CPU statistics when the                  
                        program exits                                
-delayed-insertdelayed-insertWrite INSERT DELAYED statements              
                        rather than INSERT statements                
-delete-master-logsdelete-master-logsOn a master replication server,              
                        delete the binary logs after                 
                        performing the dump operation                
-disable-keysdisable-keysFor each table, surround the INSERT          
                        statements with disable and  enable          
                        keys statements                              
-dump-date  dump-date   Include dump date in "Dump           6.0.4   
                        completed on" comment if -comments           
                        is  given                                    
-dump-slave[=value]dump-slave  Include CHANGE MASTER statement      6.0.4   
                        that lists binary log coordinates            
                        of slave's master                            
-E          events      Dump events from the dumped                  
                        databases                                    
-extended-insertextended-insertUse multiple-row INSERT syntax that          
                        include several VALUES lists                 
-fields-enclosed-by=stringfields-enclosed-byThis option is used with the -T              
                        option and has the same meaning as           
                        the corresponding clause for LOAD            
                        DATA INFILE                                  
-fields-escaped-byfields-escaped-byThis option is used with the -T              
                        option and has the same meaning as           
                        the corresponding clause for LOAD            
                        DATA INFILE                                  
-fields-optionally-enclosed-by=stringfields-optionally-enclosed-byThis option is used with the -T              
                        option and has the same meaning as           
                        the corresponding clause for LOAD            
                        DATA INFILE                                  
-fields-terminated-by=stringfields-terminated-byThis option is used with the -T              
                        option and has the same meaning as           
                        the corresponding clause for LOAD            
                        DATA INFILE                                  
-lock-all-tablesfirst-slave Deprecated. Now renamed to                   
                        -lock-all-tables                             
-flush-logs flush-logs  Flush the MySQL server log files             
                        before starting the dump                     
-flush-privilegesflush-privilegesEmit a FLUSH PRIVILEGES statement            
                        after dumping the mysql database             
-help                   Display help message and exit                
-hex-blob   hex-blob    Dump binary columns using                    
                        hexadecimal notation (for example,           
                        'abc'  becomes 0x616263)                     
-ignore-table=db_name.tbl_nameignore-tableDo not dump the given table                  
-include-master-host-portinclude-master-host-portInclude MASTER_HOST/MASTER_PORT      6.0.4   
                        options in CHANGE MASTER statement           
                        produced with -dump-slave                    
-insert-ignoreinsert-ignoreWrite INSERT statements with the             
                        IGNORE option                                
-lines-terminated-by=stringlines-terminated-byThis option is used with the -T              
                        option and has the same meaning as           
                        the corresponding clause for LOAD            
                        DATA INFILE                                  
-lock-all-tableslock-all-tablesLock all tables across all databases         
-lock-tableslock-tables Lock all tables before dumping them          
-log-error=file_namelog-error   Append warnings and errors to the            
                        named file                                   
-master-data[=value]master-data Write the binary log file name and           
                        position to the output                       
-max_allowed_packet=valuemax_allowed_packetThe maximum packet length to send            
                        to or receive from the server                
-net_buffer_length=valuenet_buffer_lengthThe buffer size for TCP/IP and               
                        socket communication                         
-no-autocommitno-autocommitEnclose the INSERT statements for            
                        each dumped table within SET                 
                        autocommit = 0 and COMMIT statements         
-no-create-dbno-create-dbThis option suppresses the CREATE            
                        DATABASE statements                          
-no-create-infono-create-infoDo not write CREATE TABLE                    
                        statements that re-create each               
                        dumped  table                                
-no-data    no-data     Do not write any table row                   
                        information (that is, do not dump            
                        table  contents)                             
-no-set-namesno-set-namesTurn off complete-insert                     
-opt        opt         This option is shorthand; it is the          
                        same as specifying  -add-drop-table          
                        -add-locks -create-options                   
                        -disable-keys  -extended-insert              
                        -lock-tables -quick -set-charset.            
-order-by-primaryorder-by-primarySorts each table's rows by its               
                        primary key, or by its first unique          
                        index                                        
-password[=password]password    The password to use when connecting          
                        to the server                                
-pipe                   On Windows, connect to server via a          
                        named pipe                                   
-port=port_numport        The TCP/IP port number to use for            
                        the connection                               
-quick      quick       Retrieve rows for a table from the           
                        server a row at a time                       
-quote-namesquote-names Quote database, table, and column            
                        names within backtick characters             
-replace    replace     Write REPLACE statements rather              
                        than INSERT statements                       
-result-file=fileresult-file Direct output to a given file                
-R          routines    Dump stored routines (procedures             
                        and functions) from the dumped               
                        databases                                    
-set-charsetset-charset Add SET NAMES default_character_set          
                        to the output                                
-single-transactionsingle-transactionThis option issues a BEGIN SQL               
                        statement before dumping data from           
                        the server                                   
-skip-add-drop-tableskip-add-drop-tableDo not add                                   
-skip-add-locksskip-add-locksDo not add locks                             
-skip-commentsskip-commentsDo not add comments to the dump file         
-skip-compactskip-compactTurn off compact                             
-skip-disable-keysskip-disable-keysDo not disable keys                          
-skip-extended-insertskip-extended-insertTurn off extended-insert                     
-skip-opt   skip-opt    Turn off the options set by opt              
-skip-quick skip-quick  Do not retrieve rows for a table             
                        from the server a row at a time              
-skip-quote-namesskip-quote-namesTurn off quote names                         
-skip-set-charsetskip-set-charsetSuppress the SET NAMES statement             
-skip-triggersskip-triggersTurn off triggers                            
-skip-tz-utcskip-tz-utc Turn off tz-utc                              
-ssl-ca=file_namessl-ca      The path to a file that contains a           
                        list of trusted SSL CAs                      
-ssl-capath=directory_namessl-capath  The path to a directory that                 
                        contains trusted SSL CA                      
                        certificates  in PEM format                  
-ssl-cert=file_namessl-cert    The name of the SSL certificate              
                        file to use for establishing a               
                        secure connection                            
-ssl-cipher=cipher_listssl-cipher  A list of allowable ciphers to use           
                        for SSL encryption                           
-ssl-key=file_namessl-key     The name of the SSL key file to use          
                        for establishing a secure                    
                        connection                                   
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in            
                        its certificate is verified                  
                        against the host name used when              
                        connecting to the server                     
-tab=path   tab         Produce tab-separated data files             
-tables     tables      Override the -databases or -B option         
-triggers   triggers    Dump triggers for each dumped table          
-tz-utc     tz-utc      Add SET TIME_ZONE='+00:00' to the            
                        dump file                                    
-verbose                Verbose mode                                 
-version                Display version information and exit         
-where='where_condition'where       Dump only rows selected by the               
                        given WHERE condition                        
-xml        xml         Produce XML output                           

*Note `mysqldump': mysqldump. supports the options in the following
list. It also reads option files and supports the options for
processing them described at *Note option-file-options::.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--add-drop-database'

     Add a *Note `DROP DATABASE': drop-database. statement before each
     *Note `CREATE DATABASE': create-database.  statement.

   *  `--add-drop-table'

     Add a *Note `DROP TABLE': drop-table. statement before each *Note
     `CREATE TABLE': create-table.  statement.

   *  `--add-locks'

     Surround each table dump with *Note `LOCK TABLES': lock-tables. and
     *Note `UNLOCK TABLES': lock-tables. statements. This results in
     faster inserts when the dump file is reloaded. See *Note
     insert-speed::.

   *  `--all-databases', `-A'

     Dump all tables in all databases. This is the same as using the
     `--databases' option and naming all the databases on the command
     line.

   *  `--allow-keywords'

     Allow creation of column names that are keywords. This works by
     prefixing each column name with the table name.

   *  `--apply-slave-statements'

     For a slave dump produced with the `--dump-slave' option, add a
     *Note `STOP SLAVE': stop-slave. statement before the *Note `CHANGE
     MASTER TO': change-master-to.  statement and a *Note `START
     SLAVE': start-slave.  statement at the end of the output. This
     option was added in MySQL 6.0.4.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--comments', `-i'

     Write additional information in the dump file such as program
     version, server version, and host. This option is enabled by
     default. To suppress this additional information, use
     `--skip-comments'.

   *  `--compact'

     Produce less verbose output. This option enables the
     `--skip-add-drop-table', `--skip-add-locks', `--skip-comments',
     `--skip-disable-keys', and `--skip-set-charset' options.

   *  `--compatible=NAME'

     Produce output that is more compatible with other database systems
     or with older MySQL servers. The value of `name' can be `ansi',
     `mysql323', `mysql40', `postgresql', `oracle', `mssql', `db2',
     `maxdb', `no_key_options', `no_table_options', or
     `no_field_options'. To use several values, separate them by
     commas. These values have the same meaning as the corresponding
     options for setting the server SQL mode. See *Note
     server-sql-mode::.

     This option does not guarantee compatibility with other servers.
     It only enables those SQL mode values that are currently available
     for making dump output more compatible.  For example,
     `--compatible=oracle' does not map data types to Oracle types or
     use Oracle comment syntax.

     _This option requires a server version of 4.1.0 or higher_. With
     older servers, it does nothing.

   *  `--complete-insert', `-c'

     Use complete *Note `INSERT': insert.  statements that include
     column names.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--create-options'

     Include all MySQL-specific table options in the *Note `CREATE
     TABLE': create-table. statements.

   *  `--databases', `-B'

     Dump several databases. Normally, *Note `mysqldump': mysqldump.
     treats the first name argument on the command line as a database
     name and following names as table names. With this option, it
     treats all name arguments as database names. *Note `CREATE
     DATABASE': create-database. and *Note `USE': use.  statements are
     included in the output before each new database.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default value is
     `'d:t:o,/tmp/mysqldump.trace''.

   *  `--debug-check'

     Print some debugging information when the program exits.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.  If no character set is specified, *Note
     `mysqldump': mysqldump. uses `utf8', and earlier versions use
     `latin1'.

     This option has no effect for output data files produced by using
     the `--tab' option.  See the description for that option.

   *  `--delayed-insert'

     Write *Note `INSERT DELAYED': insert-delayed.  statements rather
     than *Note `INSERT': insert.  statements.

   *  `--delete-master-logs'

     On a master replication server, delete the binary logs after
     performing the dump operation. This option automatically enables
     `--master-data'.

   *  `--disable-keys', `-K'

     For each table, surround the *Note `INSERT': insert. statements
     with `/*!40000 ALTER TABLE TBL_NAME DISABLE KEYS */;' and
     `/*!40000 ALTER TABLE TBL_NAME ENABLE KEYS */;' statements. This
     makes loading the dump file faster because the indexes are created
     after all rows are inserted. This option is effective only for
     non-unique indexes of `MyISAM' tables.

   *  `--dump-date'

     *Note `mysqldump': mysqldump. produces a `-- Dump completed on
     DATE' comment at the end of the dump if the `--comments' option is
     given. However, the date causes dump files for identical data take
     at different times to appear to be different.  `--dump-date' and
     `--skip-dump-date' control whether the date is added to the
     comment. The default is `--dump-date' (include the date in the
     comment).  `--skip-dump-date' suppresses date printing. This
     option was added in MySQL 6.0.4.

   *  `--dump-slave[=VALUE]'

     This option is similar to `--master-data' except that it is used
     to dump a replication slave server to produce a dump file that can
     be used to set up another server as a slave that has the same
     master as the dumped server. It causes the dump output to include a
     *Note `CHANGE MASTER TO': change-master-to. statement that
     indicates the binary log coordinates (file name and position) of
     the dumped slave's master (rather than the coordinates of the
     dumped server, as is done by the `--master-data' option).  These
     are the master server coordinates from which the slave should
     start replicating. This option was added in MySQL 6.0.4.

     The option value is handled the same way as for `--master-data'
     and has the same effect as `--master-data' in terms of enabling or
     disabling other options and in how locking is handled.

     In conjunction with `--dump-slave', the `--apply-slave-statements'
     and `--include-master-host-port' options can also be used.

   *  `--events', `-E'

     Dump events from the dumped databases.

   *  `--extended-insert', `-e'

     Use multiple-row *Note `INSERT': insert.  syntax that include
     several `VALUES' lists.  This results in a smaller dump file and
     speeds up inserts when the file is reloaded.

   *  `--fields-terminated-by=...',

     `--fields-enclosed-by=...',

     `--fields-optionally-enclosed-by=...',

     `--fields-escaped-by=...'

     These options are used with the `-T' option and have the same
     meaning as the corresponding clauses for *Note `LOAD DATA INFILE':
     load-data. See *Note load-data::.

   *  `--first-slave', `-x'

     Deprecated. Now renamed to `--lock-all-tables'.

   *  `--flush-logs', `-F'

     Flush the MySQL server log files before starting the dump.  This
     option requires the `RELOAD' privilege. Note that if you use this
     option in combination with the `--all-databases' (or `-A') option,
     the logs are flushed _for each database dumped_. The exception is
     when using `--lock-all-tables' or `--master-data': In this case,
     the logs are flushed only once, corresponding to the moment that
     all tables are locked. If you want your dump and the log flush to
     happen at exactly the same moment, you should use `--flush-logs'
     together with either `--lock-all-tables' or `--master-data'.

   *  `--flush-privileges'

     Emit a *Note `FLUSH PRIVILEGES': flush. statement after dumping the
     `mysql' database. This option should be used any time the dump
     contains the `mysql' database and any other database that depends
     on the data in the `mysql' database for proper restoration.

   *  `--force', `-f'

     Continue even if an SQL error occurs during a table dump.

     One use for this option is to cause *Note `mysqldump': mysqldump.
     to continue executing even when it encounters a view that has
     become invalid because the definition refers to a table that has
     been dropped. Without `--force', *Note `mysqldump': mysqldump.
     exits with an error message.  With `--force', *Note `mysqldump':
     mysqldump. prints the error message, but it also writes an SQL
     comment containing the view definition to the dump output and
     continues executing.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Dump data from the MySQL server on the given host. The default
     host is `localhost'.

   *  `--hex-blob'

     Dump binary columns using hexadecimal notation (for example,
     `'abc'' becomes `0x616263'). The affected data types are *Note
     `BINARY': binary-varbinary, *Note `VARBINARY': binary-varbinary,
     *Note `BLOB': blob, and *Note `BIT': numeric-types.

   *  `--include-master-host-port'

     For the *Note `CHANGE MASTER TO': change-master-to.  statement in
     a slave dump produced with the `--dump-slave' option, add
     `MASTER_PORT' and `MASTER_PORT' options for the host name and
     TCP/IP port number of the slave's master. This option was added in
     MySQL 6.0.4.

   *  `--ignore-table=DB_NAME.TBL_NAME'

     Do not dump the given table, which must be specified using both
     the database and table names. To ignore multiple tables, use this
     option multiple times. This option also can be used to ignore
     views.

   *  `--insert-ignore'

     Write *Note `INSERT': insert. statements with the `IGNORE' option.

   *  `--lines-terminated-by=...'

     This option is used with the `-T' option and has the same meaning
     as the corresponding clause for *Note `LOAD DATA INFILE':
     load-data. See *Note load-data::.

   *  `--lock-all-tables', `-x'

     Lock all tables across all databases. This is achieved by
     acquiring a global read lock for the duration of the whole dump.
     This option automatically turns off `--single-transaction' and
     `--lock-tables'.

   *  `--lock-tables', `-l'

     Lock all tables before dumping them. The tables are locked with
     `READ LOCAL' to allow concurrent inserts in the case of `MyISAM'
     tables. For transactional tables such as `InnoDB' and `BDB',
     `--single-transaction' is a much better option, because it does
     not need to lock the tables at all.

     Please note that when dumping multiple databases, `--lock-tables'
     locks tables for each database separately. Therefore, this option
     does not guarantee that the tables in the dump file are logically
     consistent between databases. Tables in different databases may be
     dumped in completely different states.

   *  `--log-error=FILE_NAME'

     Append warnings and errors to the named file.

   *  `--master-data[=VALUE]'

     Use this option to dump a master replication server to produce a
     dump file that can be used to set up another server as a slave of
     the master. It causes the dump output to include a *Note `CHANGE
     MASTER TO': change-master-to.  statement that indicates the binary
     log coordinates (file name and position) of the dumped server.
     These are the master server coordinates from which the slave
     should start replicating.

     If the option value is 2, the *Note `CHANGE MASTER TO':
     change-master-to. statement is written as an SQL comment, and thus
     is informative only; it has no effect when the dump file is
     reloaded. If the option value is 1, the statement takes effect
     when the dump file is reloaded. If the option value is not
     specified, the default value is 1.

     This option requires the `RELOAD' privilege and the binary log
     must be enabled.

     The `--master-data' option automatically turns off
     `--lock-tables'. It also turns on `--lock-all-tables', unless
     `--single-transaction' also is specified, in which case, a global
     read lock is acquired only for a short time at the beginning of
     the dump (see the description for `--single-transaction'). In all
     cases, any action on logs happens at the exact moment of the dump.

     It is also possible to set up a slave by dumping an existing slave
     of the master. To do this, use the `--dump-slave' option instead.

   *  `--no-autocommit'

     Enclose the *Note `INSERT': insert. statements for each dumped
     table within `SET autocommit = 0' and *Note `COMMIT': commit.
     statements.

   *  `--no-create-db', `-n'

     This option suppresses the *Note `CREATE DATABASE':
     create-database. statements that are otherwise included in the
     output if the `--databases' or `--all-databases' option is given.

   *  `--no-create-info', `-t'

     Do not write *Note `CREATE TABLE': create-table.  statements that
     re-create each dumped table.

   *  `--no-data', `-d'

     Do not write any table row information (that is, do not dump table
     contents). This is very useful if you want to dump only the *Note
     `CREATE TABLE': create-table.  statement for the table.

   *  `--opt'

     This option is shorthand; it is the same as specifying
     `--add-drop-table' `--add-locks' `--create-options'
     `--disable-keys' `--extended-insert' `--lock-tables' `--quick'
     `--set-charset'. It should give you a fast dump operation and
     produce a dump file that can be reloaded into a MySQL server
     quickly.

     _The `--opt' option is enabled by default. Use `--skip-opt' to
     disable it._ See the discussion at the beginning of this section
     for information about selectively enabling or disabling certain of
     the options affected by `--opt'.

   *  `--order-by-primary'

     Sorts each table's rows by its primary key, or by its first unique
     index, if such an index exists. This is useful when dumping a
     `MyISAM' table to be loaded into an `InnoDB' table, but will make
     the dump itself take considerably longer.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--quick', `-q'

     This option is useful for dumping large tables. It forces *Note
     `mysqldump': mysqldump. to retrieve rows for a table from the
     server a row at a time rather than retrieving the entire row set
     and buffering it in memory before writing it out.

   *  `--quote-names', `-Q'

     Quote database, table, and column names within ```'' characters.
     If the `ANSI_QUOTES' SQL mode is enabled, names are quoted within
     ``"'' characters. This option is enabled by default. It can be
     disabled with `--skip-quote-names', but this option should be
     given after any option such as `--compatible' that may enable
     `--quote-names'.

   *  `--replace'

     Write *Note `REPLACE': replace. statements rather than *Note
     `INSERT': insert.  statements.

   *  `--result-file=FILE_NAME', `-r FILE_NAME'

     Direct output to a given file. This option should be used on
     Windows to prevent newline ``\n'' characters from being converted
     to ``\r\n'' carriage return/newline sequences. The result file is
     created and its contents overwritten, even if an error occurs while
     generating the dump. The previous contents are lost.

   *  `--routines', `-R'

     Dump stored routines (procedures and functions) from the dumped
     databases. Use of this option requires the `SELECT' privilege for
     the `mysql.proc' table. The output generated by using `--routines'
     contains *Note `CREATE PROCEDURE': create-procedure. and *Note
     `CREATE FUNCTION': create-function. statements to re-create the
     routines. However, these statements do not include attributes such
     as the routine creation and modification timestamps. This means
     that when the routines are reloaded, they will be created with the
     timestamps equal to the reload time.

     If you require routines to be re-created with their original
     timestamp attributes, do not use `--routines'. Instead, dump and
     reload the contents of the `mysql.proc' table directly, using a
     MySQL account that has appropriate privileges for the `mysql'
     database.

   *  `--set-charset'

     Add `SET NAMES DEFAULT_CHARACTER_SET' to the output. This option
     is enabled by default. To suppress the `SET NAMES' statement, use
     `--skip-set-charset'.

   *  `--single-transaction'

     This option issues a *Note `BEGIN': commit. SQL statement before
     dumping data from the server. It is useful only with transactional
     tables such as `InnoDB', because then it dumps the consistent
     state of the database at the time when *Note `BEGIN': commit. was
     issued without blocking any applications.

     When using this option, you should keep in mind that only `InnoDB'
     and `Falcon' tables are dumped in a consistent state. For example,
     any `MyISAM' or `MEMORY' tables dumped while using this option may
     still change state.

     While a `--single-transaction' dump is in process, to ensure a
     valid dump file (correct table contents and binary log position),
     no other connection should use the following statements: *Note
     `ALTER TABLE': alter-table, *Note `DROP TABLE': drop-table, *Note
     `RENAME TABLE': rename-table, *Note `TRUNCATE TABLE': truncate. A
     consistent read is not isolated from those statements, so use of
     them on a table to be dumped can cause the *Note `SELECT': select.
     performed by *Note `mysqldump': mysqldump. to retrieve the table
     contents to obtain incorrect contents or fail.

     The `--single-transaction' option and the `--lock-tables' option
     are mutually exclusive, because *Note `LOCK TABLES': lock-tables.
     causes any pending transactions to be committed implicitly.

     To dump large tables, you should combine this option with
     `--quick'.

   *  `--skip-comments'

     See the description for the `--comments' option.

   *  `--skip-opt'

     See the description for the `--opt' option.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--tab=PATH', `-T PATH'

     Produce tab-separated data files. For each dumped table, *Note
     `mysqldump': mysqldump. creates a `TBL_NAME.sql' file that
     contains the *Note `CREATE TABLE': create-table. statement that
     creates the table, and a `TBL_NAME.txt' file that contains its
     data. The option value is the directory in which to write the
     files.

     By default, the `.txt' data files are formatted using tab
     characters between column values and a newline at the end of each
     line. The format can be specified explicitly using the
     `--fields-XXX' and `--lines-terminated-by' options.

     Column values are dumped using the `binary' character set and the
     `--default-character-set' option is ignored. In effect, there is
     no character set conversion. If a table contains columns in
     several character sets, the output data file will as well and you
     may not be able to reload the file correctly.

     *Note*:

     This option should be used only when *Note `mysqldump': mysqldump.
     is run on the same machine as the *Note `mysqld': mysqld. server.
     You must have the `FILE' privilege, and the server must have
     permission to write files in the directory that you specify.

   *  `--tables'

     Override the `--databases' or `-B' option. *Note `mysqldump':
     mysqldump.  regards all name arguments following the option as
     table names.

   *  `--triggers'

     Dump triggers for each dumped table. This option is enabled by
     default; disable it with `--skip-triggers'.

   *  `--tz-utc'

     This option enables *Note `TIMESTAMP': datetime.  columns to be
     dumped and reloaded between servers in different time zones. *Note
     `mysqldump': mysqldump. sets its connection time zone to UTC and
     adds `SET TIME_ZONE='+00:00'' to the dump file. Without this
     option, *Note `TIMESTAMP': datetime. columns are dumped and
     reloaded in the time zones local to the source and destination
     servers, which can cause the values to change. `--tz-utc' also
     protects against changes due to daylight saving time.  `--tz-utc'
     is enabled by default. To disable it, use `--skip-tz-utc'.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL user name to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.

   *  `--version', `-V'

     Display version information and exit.

   *  `--where='WHERE_CONDITION'', `-w 'WHERE_CONDITION''

     Dump only rows selected by the given `WHERE' condition. Quotes
     around the condition are mandatory if it contains spaces or other
     characters that are special to your command interpreter.

     Examples:

          --where="user='jimf'"
          -w"userid>1"
          -w"userid<1"

   *  `--xml', `-X'

     Write dump output as well-formed XML.

     *`NULL', `'NULL'', and Empty Values*: For some column named
     COLUMN_NAME, the `NULL' value, an empty string, and the string
     value `'NULL'' are distinguished from one another in the output
     generated by this option as follows.

     *Value*:                           *XML Representation*:
     `NULL' (_unknown value_)           `<field name="COLUMN_NAME"
                                        xsi:nil="true" />'
     `''' (_empty string_)              `<field
                                        name="COLUMN_NAME"></field>'
     `'NULL'' (_string value_)          `<field
                                        name="COLUMN_NAME">NULL</field>'

     The output from the *Note `mysql': mysql. client when run using
     the `--xml' option also follows these rules. (See *Note
     mysql-command-options::.)

     XML output from *Note `mysqldump': mysqldump. includes the XML
     namespace, as shown here:

          shell> mysqldump --xml -u root world City
          <?xml version="1.0"?>
          <mysqldump xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
          <database name="world">
          <table_structure name="City">
          <field Field="ID" Type="int(11)" Null="NO" Key="PRI" Extra="auto_increment" />
          <field Field="Name" Type="char(35)" Null="NO" Key="" Default="" Extra="" />
          <field Field="CountryCode" Type="char(3)" Null="NO" Key="" Default="" Extra="" />
          <field Field="District" Type="char(20)" Null="NO" Key="" Default="" Extra="" />
          <field Field="Population" Type="int(11)" Null="NO" Key="" Default="0" Extra="" />
          <key Table="City" Non_unique="0" Key_name="PRIMARY" Seq_in_index="1" Column_name="ID" Collation="A" Cardinality="4079"
          Null="" Index_type="BTREE" Comment="" />
          <options Name="City" Engine="MyISAM" Version="10" Row_format="Fixed" Rows="4079" Avg_row_length="67" Data_length="27329
          3" Max_data_length="18858823439613951" Index_length="43008" Data_free="0" Auto_increment="4080" Create_time="2007-03-31 01:47:01" Updat
          e_time="2007-03-31 01:47:02" Collation="latin1_swedish_ci" Create_options="" Comment="" />
          </table_structure>
          <table_data name="City">
          <row>
          <field name="ID">1</field>
          <field name="Name">Kabul</field>
          <field name="CountryCode">AFG</field>
          <field name="District">Kabol</field>
          <field name="Population">1780000</field>
          </row>

          ...

          <row>
          <field name="ID">4079</field>
          <field name="Name">Rafah</field>
          <field name="CountryCode">PSE</field>
          <field name="District">Rafah</field>
          <field name="Population">92020</field>
          </row>
          </table_data>
          </database>
          </mysqldump>

You can also set the following variables by using `--VAR_NAME=VALUE'
syntax:

   * `max_allowed_packet'

     The maximum size of the buffer for client/server communication.
     The maximum is 1GB.

   *  `net_buffer_length'

     The initial size of the buffer for client/server communication.
     When creating multiple-row-insert statements (as with option
     `--extended-insert' or `--opt'), *Note `mysqldump': mysqldump.
     creates rows up to `net_buffer_length' length.  If you increase
     this variable, you should also ensure that the `net_buffer_length'
     variable in the MySQL server is at least this large.

The most common use of *Note `mysqldump': mysqldump. is probably for
making a backup of an entire database:

     shell> mysqldump DB_NAME > BACKUP-FILE.SQL

You can read the dump file back into the server like this:

     shell> mysql DB_NAME < BACKUP-FILE.SQL

Or like this:

     shell> mysql -e "source /PATH-TO-BACKUP/BACKUP-FILE.SQL" DB_NAME

*Note `mysqldump': mysqldump. is also very useful for populating
databases by copying data from one MySQL server to another:

     shell> mysqldump --opt DB_NAME | mysql --host=REMOTE_HOST -C DB_NAME

It is possible to dump several databases with one command:

     shell> mysqldump --databases DB_NAME1 [DB_NAME2 ...] > my_databases.sql

To dump all databases, use the `--all-databases' option:

     shell> mysqldump --all-databases > all_databases.sql

For `InnoDB' tables, *Note `mysqldump': mysqldump. provides a way of
making an online backup:

     shell> mysqldump --all-databases --single-transaction > all_databases.sql

This backup acquires a global read lock on all tables (using *Note
`FLUSH TABLES WITH READ LOCK': flush.) at the beginning of the dump. As
soon as this lock has been acquired, the binary log coordinates are
read and the lock is released. If long updating statements are running
when the *Note `FLUSH': flush. statement is issued, the MySQL server
may get stalled until those statements finish. After that, the dump
becomes lock-free and does not disturb reads and writes on the tables.
If the update statements that the MySQL server receives are short (in
terms of execution time), the initial lock period should not be
noticeable, even with many updates.

For point-in-time recovery (also known as `roll-forward,' when you need
to restore an old backup and replay the changes that happened since
that backup), it is often useful to rotate the binary log (see *Note
binary-log::) or at least know the binary log coordinates to which the
dump corresponds:

     shell> mysqldump --all-databases --master-data=2 > all_databases.sql

Or:

     shell> mysqldump --all-databases --flush-logs --master-data=2
                   > all_databases.sql

The `--master-data' and `--single-transaction' options can be used
simultaneously, which provides a convenient way to make an online
backup suitable for point-in-time recovery if tables are stored using
the `InnoDB' storage engine.

For more information on making backups, see *Note backup::, and *Note
backup-strategy-example::.

If you encounter problems backing up views, please read the section
that covers restrictions on views which describes a workaround for
backing up views when this fails due to insufficient privileges. See
*Note view-restrictions::.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about *Note
`mysqldump': mysqldump. in the Knowledge Base article, How Can I Avoid
Inserting Duplicate Rows From a Dump File?
(https://kb.mysql.com/view.php?id=5285).  Access to the MySQL Knowledge
Base collection of articles is one of the advantages of subscribing to
MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: mysqlimport,  Next: mysqlshow,  Prev: mysqldump,  Up: programs-client

4.5.5 `mysqlimport' -- A Data Import Program
--------------------------------------------

The *Note `mysqlimport': mysqlimport. client provides a command-line
interface to the *Note `LOAD DATA INFILE': load-data. SQL statement.
Most options to *Note `mysqlimport': mysqlimport. correspond directly
to clauses of *Note `LOAD DATA INFILE': load-data. syntax. See *Note
load-data::.

Invoke *Note `mysqlimport': mysqlimport. like this:

     shell> mysqlimport [OPTIONS] DB_NAME TEXTFILE1 [TEXTFILE2 ...]

For each text file named on the command line, *Note `mysqlimport':
mysqlimport. strips any extension from the file name and uses the
result to determine the name of the table into which to import the
file's contents. For example, files named `patient.txt',
`patient.text', and `patient' all would be imported into a table named
`patient'.

*`mysqlimport' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-columns=column_listcolumns     This option takes a comma-separated          
                        list of column names as its  value           
-compress   compress    Compress all information sent                
                        between the client and the server            
-debug[=debug_options]debug       Write a debugging log                        
-debug-checkdebug-check Print debugging information when             
                        the program exits                            
-debug-info debug-info  Print debugging information, memory          
                        and CPU statistics when the                  
                        program exits                                
-default-character-set=charset_namedefault-character-setUse charset_name as the default              
                        character set                                
-delete     delete      Empty the table before importing             
                        the text file                                
-fields-enclosed-by=stringfields-enclosed-byThis option has the same meaning as          
                        the corresponding clause for  LOAD           
                        DATA INFILE                                  
-fields-escaped-byfields-escaped-byThis option has the same meaning as          
                        the corresponding clause for  LOAD           
                        DATA INFILE                                  
-fields-optionally-enclosed-by=stringfields-optionally-enclosed-byThis option has the same meaning as          
                        the corresponding clause for  LOAD           
                        DATA INFILE                                  
-fields-terminated-by=stringfields-terminated-by- This option has the same meaning           
                        as the corresponding clause  for             
                        LOAD DATA INFILE                             
-force      force       Continue even if an SQL error occurs         
-help                   Display help message and exit                
-host=host_namehost        Connect to the MySQL server on the           
                        given host                                   
-ignore     ignore      See the description for the                  
                        -replace option                              
-ignore-lines=#ignore-linesIgnore the first N lines of the              
                        data file                                    
-lines-terminated-by=stringlines-terminated-byThis option has the same meaning as          
                        the corresponding clause for  LOAD           
                        DATA INFILE                                  
-local      local       Read input files locally from the            
                        client host                                  
-lock-tableslock-tables Lock all tables for writing before           
                        processing any text files                    
-low-prioritylow-priorityUse LOW_PRIORITY when loading the            
                        table.                                       
-password[=password]password    The password to use when connecting          
                        to the server                                
-pipe                   On Windows, connect to server via a          
                        named pipe                                   
-port=port_numport        The TCP/IP port number to use for            
                        the connection                               
-protocol=typeprotocol    The connection protocol to use               
-replace    replace     The -replace and -ignore options             
                        control handling of input rows               
                        that duplicate existing rows on              
                        unique key values                            
-silent     silent      Produce output only when errors              
                        occur                                        
-socket=pathsocket      For connections to localhost                 
-ssl-ca=file_namessl-ca      The path to a file that contains a           
                        list of trusted SSL CAs                      
-ssl-capath=directory_namessl-capath  The path to a directory that                 
                        contains trusted SSL CA                      
                        certificates  in PEM format                  
-ssl-cert=file_namessl-cert    The name of the SSL certificate              
                        file to use for establishing a               
                        secure connection                            
-ssl-cipher=cipher_listssl-cipher  A list of allowable ciphers to use           
                        for SSL encryption                           
-ssl-key=file_namessl-key     The name of the SSL key file to use          
                        for establishing a secure                    
                        connection                                   
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in            
                        its certificate is verified                  
                        against the host name used when              
                        connecting to the server                     
-use-threads=#use-threads The number of threads for parallel           
                        file-loading                                 
-user=user_name,user        The MySQL user name to use when              
                        connecting to the server                     
-verbose                Verbose mode                                 
-version                Display version information and exit         

*Note `mysqlimport': mysqlimport. supports the options in the following
list. It also reads option files and supports the options for
processing them described at *Note option-file-options::.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--columns=COLUMN_LIST', `-c COLUMN_LIST'

     This option takes a comma-separated list of column names as its
     value. The order of the column names indicates how to match data
     file columns with table columns.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is `'d:t:o''.

   *  `--debug-check'

     Print some debugging information when the program exits.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.

   *  `--delete', `-D'

     Empty the table before importing the text file.

   *  `--fields-terminated-by=...',

     `--fields-enclosed-by=...',

     `--fields-optionally-enclosed-by=...',

     `--fields-escaped-by=...'

     These options have the same meaning as the corresponding clauses
     for *Note `LOAD DATA INFILE': load-data. See *Note load-data::.

   *  `--force', `-f'

     Ignore errors. For example, if a table for a text file does not
     exist, continue processing any remaining files. Without `--force',
     *Note `mysqlimport': mysqlimport. exits if a table does not exist.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Import data to the MySQL server on the given host. The default
     host is `localhost'.

   *  `--ignore', `-i'

     See the description for the `--replace' option.

   *  `--ignore-lines=N'

     Ignore the first N lines of the data file.

   *  `--lines-terminated-by=...'

     This option has the same meaning as the corresponding clause for
     *Note `LOAD DATA INFILE': load-data. For example, to import
     Windows files that have lines terminated with carriage
     return/linefeed pairs, use `--lines-terminated-by="\r\n"'.  (You
     might have to double the backslashes, depending on the escaping
     conventions of your command interpreter.) See *Note load-data::.

   *  `--local', `-L'

     Read input files locally from the client host.

     MySQL Enterprise

     For expert advice on the security implications of enabling
     `LOCAL', subscribe to the MySQL Enterprise Monitor. For more
     information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--lock-tables', `-l'

     Lock _all_ tables for writing before processing any text files.
     This ensures that all tables are synchronized on the server.

   *  `--low-priority'

     Use `LOW_PRIORITY' when loading the table.  This affects only
     storage engines that use only table-level locking (`MyISAM',
     `MEMORY', `MERGE').

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--replace', `-r'

     The `--replace' and `--ignore' options control handling of input
     rows that duplicate existing rows on unique key values. If you
     specify `--replace', new rows replace existing rows that have the
     same unique key value.  If you specify `--ignore', input rows that
     duplicate an existing row on a unique key value are skipped. If
     you do not specify either option, an error occurs when a duplicate
     key value is found, and the rest of the text file is ignored.

   *  `--silent', `-s'

     Silent mode. Produce output only when errors occur.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL user name to use when connecting to the server.

   *  `--use-threads=N'

     Load files in parallel using N threads.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.

   *  `--version', `-V'

     Display version information and exit.

Here is a sample session that demonstrates use of *Note `mysqlimport':
mysqlimport.:

     shell> mysql -e 'CREATE TABLE imptest(id INT, n VARCHAR(30))' test
     shell> ed
     a
     100     Max Sydow
     101     Count Dracula
     .
     w imptest.txt
     32
     q
     shell> od -c imptest.txt
     0000000   1   0   0  \t   M   a   x       S   y   d   o   w  \n   1   0
     0000020   1  \t   C   o   u   n   t       D   r   a   c   u   l   a  \n
     0000040
     shell> mysqlimport --local test imptest.txt
     test.imptest: Records: 2  Deleted: 0  Skipped: 0  Warnings: 0
     shell> mysql -e 'SELECT * FROM imptest' test
     +------+---------------+
     | id   | n             |
     +------+---------------+
     |  100 | Max Sydow     |
     |  101 | Count Dracula |
     +------+---------------+


File: manual.info,  Node: mysqlshow,  Next: mysqlslap,  Prev: mysqlimport,  Up: programs-client

4.5.6 `mysqlshow' -- Display Database, Table, and Column Information
--------------------------------------------------------------------

The *Note `mysqlshow': mysqlshow. client can be used to quickly see
which databases exist, their tables, or a table's columns or indexes.

*Note `mysqlshow': mysqlshow. provides a command-line interface to
several SQL *Note `SHOW': show. statements.  See *Note show::. The same
information can be obtained by using those statements directly. For
example, you can issue them from the *Note `mysql': mysql. client
program.

Invoke *Note `mysqlshow': mysqlshow. like this:

     shell> mysqlshow [OPTIONS] [DB_NAME [TBL_NAME [COL_NAME]]]

   * If no database is given, a list of database names is shown.

   * If no table is given, all matching tables in the database are
     shown.

   * If no column is given, all matching columns and column types in
     the table are shown.

The output displays only the names of those databases, tables, or
columns for which you have some privileges.

If the last argument contains shell or SQL wildcard characters (``*'',
``?'', ``%'', or ``_''), only those names that are matched by the
wildcard are shown. If a database name contains any underscores, those
should be escaped with a backslash (some Unix shells require two) to
get a list of the proper tables or columns. ``*'' and ``?'' characters
are converted into SQL ``%'' and ``_'' wildcard characters. This might
cause some confusion when you try to display the columns for a table
with a ``_'' in the name, because in this case, *Note `mysqlshow':
mysqlshow. shows you only the table names that match the pattern. This
is easily fixed by adding an extra ``%'' last on the command line as a
separate argument.

*`mysqlshow' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-bind-address=host_name            Determine which client network               
                        interface to use when connecting to          
                        the MySQL Server                             
-compress   compress    Compress all information sent                
                        between the client and the server            
-count      count       Show the number of rows per table            
-debug[=debug_options]debug       Write a debugging log                        
-debug-checkdebug-check Print debugging information when             
                        the program exits                            
-debug-info debug-info  Print debugging information, memory          
                        and CPU statistics when the                  
                        program exits                                
-default-character-set=charset_namedefault-character-setUse charset_name as the default              
                        character set                                
-help                   Display help message and exit                
-host=host_namehost        Connect to the MySQL server on the           
                        given host                                   
-keys       keys        Show table indexes                           
-password[=password]password    The password to use when connecting          
                        to the server                                
-pipe                   On Windows, connect to server via a          
                        named pipe                                   
-port=port_numport        The TCP/IP port number to use for            
                        the connection                               
-protocol=typeprotocol    The connection protocol to use               
-show-table-type            Show a column indicating the table           
                        type                                         
-socket=pathsocket      For connections to localhost                 
-ssl-ca=file_namessl-ca      The path to a file that contains a           
                        list of trusted SSL CAs                      
-ssl-capath=directory_namessl-capath  The path to a directory that                 
                        contains trusted SSL CA                      
                        certificates  in PEM format                  
-ssl-cert=file_namessl-cert    The name of the SSL certificate              
                        file to use for establishing a               
                        secure connection                            
-ssl-cipher=cipher_listssl-cipher  A list of allowable ciphers to use           
                        for SSL encryption                           
-ssl-key=file_namessl-key     The name of the SSL key file to use          
                        for establishing a secure                    
                        connection                                   
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in            
                        its certificate is verified                  
                        against the host name used when              
                        connecting to the server                     
-status     status      Display extra information about              
                        each table                                   
-user=user_name,user        The MySQL user name to use when              
                        connecting to the server                     
-verbose                Verbose mode                                 
-version                Display version information and exit         

*Note `mysqlshow': mysqlshow. supports the options in the following
list. It also reads option files and supports the options for
processing them described at *Note option-file-options::.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--count'

     Show the number of rows per table. This can be slow for
     non-`MyISAM' tables.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is `'d:t:o''.

   *  `--debug-check'

     Print some debugging information when the program exits.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--keys', `-k'

     Show table indexes.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--show-table-type', `-t'

     Show a column indicating the table type, as in `SHOW FULL TABLES'.
     The type is `BASE TABLE' or `VIEW'.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--status', `-i'

     Display extra information about each table.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL user name to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.
     This option can be used multiple times to increase the amount of
     information.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: mysqlslap,  Prev: mysqlshow,  Up: programs-client

4.5.7 `mysqlslap' -- Load Emulation Client
------------------------------------------

*Note `mysqlslap': mysqlslap. is a diagnostic program designed to
emulate client load for a MySQL server and to report the timing of each
stage. It works as if multiple clients are accessing the server.

Invoke *Note `mysqlslap': mysqlslap. like this:

     shell> mysqlslap [OPTIONS]

Some options such as `--create' or `--query' enable you to specify a
string containing an SQL statement or a file containing statements. If
you specify a file, by default it must contain one statement per line.
(That is, the implicit statement delimiter is the newline character.)
Use the `--delimiter' option to specify a different delimiter, which
enables you to specify statements that span multiple lines or place
multiple statements on a single line. You cannot include comments in a
file; *Note `mysqlslap': mysqlslap. does not understand them.

*Note `mysqlslap': mysqlslap. runs in three stages:

  1. Create schema, table, and optionally any stored programs or data
     you want to using for the test. This stage uses a single client
     connection.

  2. Run the load test. This stage can use many client connections.

  3. Clean up (disconnect, drop table if specified). This stage uses a
     single client connection.

Examples:

Supply your own create and query SQL statements, with 50 clients
querying and 200 selects for each:

     mysqlslap --delimiter=";" \
       --create="CREATE TABLE a (b int);INSERT INTO a VALUES (23)" \
       --query="SELECT * FROM a" --concurrency=50 --iterations=200

Let *Note `mysqlslap': mysqlslap. build the query SQL statement with a
table of two *Note `INT': numeric-types. columns and three *Note
`VARCHAR': char. columns. Use five clients querying 20 times each. Do
not create the table or insert the data (that is, use the previous
test's schema and data):

     mysqlslap --concurrency=5 --iterations=20 \
       --number-int-cols=2 --number-char-cols=3 \
       --auto-generate-sql

Tell the program to load the create, insert, and query SQL statements
from the specified files, where the `create.sql' file has multiple
table creation statements delimited by `';'' and multiple insert
statements delimited by `';''. The `--query' file will have multiple
queries delimited by `';''. Run all the load statements, then run all
the queries in the query file with five clients (five times each):

     mysqlslap --concurrency=5 \
       --iterations=5 --query=query.sql --create=create.sql \
       --delimiter=";"

*`mysqlslap' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-auto-generate-sqlauto-generate-sqlGenerate SQL statements                      
                        automatically when they are not              
                        supplied  in files or via command            
                        options                                      
-auto-generate-sql-add-auto-incrementauto-generate-sql-add-auto-incrementAdd AUTO_INCREMENT column to                 
                        automatically generated tables               
-auto-generate-sql-execute-number=#auto-generate-sql-execute-numberSpecify how many queries to                  
                        generate automatically                       
-auto-generate-sql-guid-primaryauto-generate-sql-guid-primaryAdd a GUID-based primary key to              
                        automatically generated tables               
-auto-generate-sql-load-type=typeauto-generate-sql-load-typeSpecify how many queries to                  
                        generate automatically                       
-auto-generate-sql-secondary-indexes=#auto-generate-sql-secondary-indexesSpecify how many secondary indexes           
                        to add to automatically  generated           
                        tables                                       
-auto-generate-sql-select-columns=strauto-generate-sql-select-columnsThe string to use for the select     6.0.3   
                        columns used in automatic tests              
-auto-generate-sql-unique-query-number=#auto-generate-sql-unique-query-numberHow many different queries to                
                        generate for automatic tests.                
-auto-generate-sql-unique-write-number=#auto-generate-sql-unique-write-numberHow many different queries to                
                        generate for                                 
                        -auto-generate-sql-write-number              
-auto-generate-sql-write-number=#auto-generate-sql-write-numberHow many row inserts to perform on           
                        each thread                                  
-burnin     burnin      Run the full test case in an         6.0.3   
                        infinite loop                                
-commit=#   commit      How many statements to execute               
                        before committing.                           
-compress   compress    Compress all information sent                
                        between the client and the server            
-concurrency=#concurrency The number of clients to simulate            
                        when issuing the SELECT  statement           
-create=valuecreate      The file or string containing the            
                        statement to use for creating  the           
                        table                                        
-create-schema=valuecreate-schemaThe schema in which to run the tests         
-csv=[file] csv         Generate output in comma-separated           
                        values format                                
-debug[=debug_options]debug       Write a debugging log                        
-debug-checkdebug-check Print debugging information when             
                        the program exits                            
-debug-info debug-info  Print debugging information, memory          
                        and CPU statistics when the                  
                        program exits                                
-delayed-start=#delayed-startDelay each thread start by random    6.0.3   
                        number of microseconds up to  this           
                        maximum                                      
-delimiter=strdelimiter   The delimiter to use in SQL                  
                        statements                                   
-detach=#   detach      Detach (close and reopen) each               
                        connection after each N statements           
-engine=engine_nameengine      The storage engine to use for                
                        creating the table                           
-help                   Display help message and exit                
-host=host_namehost        Connect to the MySQL server on the           
                        given host                                   
-ignore-sql-errorsignore-sql-errorsIgnore SQL errors during the test    6.0.4   
                        run                                          
-iterations=#iterations  The number of times to run the tests         
-label=str  label       The label to use in SQL statements   6.0.3   
-number-blob-cols=#number-blob-colsThe number of BLOB columns to use    6.0.3   
                        if -auto-generate-sql is  specified          
-number-char-cols=#number-char-colsThe number of VARCHAR columns to             
                        use if -auto-generate-sql is                 
                        specified                                    
-number-int-cols=#number-int-colsThe number of INT columns to use if          
                        -auto-generate-sql is  specified             
-number-of-queries=#number-of-queriesLimit each client to approximately           
                        this number of queries                       
-only-print only-print  Do not connect to databases.                 
                        mysqlslap only prints what it would          
                        have done                                    
-password[=password]password    The password to use when connecting          
                        to the server                                
-pipe                   On Windows, connect to server via a          
                        named pipe                                   
-port=port_numport        The TCP/IP port number to use for            
                        the connection                               
-post-query=valuepost-query  The file or string containing the            
                        statement to execute after the               
                        tests have completed                         
-post-system=strpost-system The string to execute via system()           
                        after the tests have completed               
-pre-query=valuepre-query   The file or string containing the            
                        statement to execute before                  
                        running the tests                            
-pre-system=strpre-system  The string to execute via system()>          
                        before running the tests                     
-preserve-schemapreserve-schemaPreserve the schema from the                 
                        mysqlslap run                                
-protocol=typeprotocol    The connection protocol to use               
-query=valuequery       The file or string containg the              
                        SELECT statement to use for                  
                        retrieving data                              
-set-random-seed=#set-random-seedThe seed value for the randomizer            
-silent     silent      Silent mode                                  
-socket=pathsocket      For connections to localhost                 
-ssl-ca=file_namessl-ca      The path to a file that contains a           
                        list of trusted SSL CAs                      
-ssl-capath=directory_namessl-capath  The path to a directory that                 
                        contains trusted SSL CA                      
                        certificates  in PEM format                  
-ssl-cert=file_namessl-cert    The name of the SSL certificate              
                        file to use for establishing a               
                        secure connection                            
-ssl-cipher=cipher_listssl-cipher  A list of allowable ciphers to use           
                        for SSL encryption                           
-ssl-key=file_namessl-key     The name of the SSL key file to use          
                        for establishing a secure                    
                        connection                                   
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in            
                        its certificate is verified                  
                        against the host name used when              
                        connecting to the server                     
-timer-length=#timer-lengthThe duration in seconds to run each  6.0.3   
                        test                                         
-user=user_name,user        The MySQL user name to use when              
                        connecting to the server                     
-verbose                Verbose mode                                 
-version                Display version information and exit         

*Note `mysqlslap': mysqlslap. supports the options in the following
list. It also reads option files and supports the options for
processing them described at *Note option-file-options::.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--auto-generate-sql', `-a'

     Generate SQL statements automatically when they are not supplied
     in files or via command options.

   *  `--auto-generate-sql-add-autoincrement'

     Add an `AUTO_INCREMENT' column to automatically generated tables.

   *  `--auto-generate-sql-execute-number=N'

     Specify how many queries to generate automatically.

   *  `--auto-generate-sql-guid-primary'

     Add a GUID-based primary key to automatically generated tables.

   *  `--auto-generate-sql-load-type=TYPE'

     Specify the test load type. The allowable values are `read' (scan
     tables), `write' (insert into tables), `key' (read primary keys),
     `update' (update primary keys), or `mixed' (half inserts, half
     scanning selects). The default is `mixed'.

   *  `--auto-generate-sql-secondary-indexes=N'

     Specify how many secondary indexes to add to automatically
     generated tables. By default, none are added.

   *  `--auto-generate-sql-select-columns=STR'

     The string to use for the select columns used in automatic tests.
     You can use this to determine the effect on performance of
     selecting or excluding particular columns.  This option was added
     in MySQL 6.0.3.

   *  `--auto-generate-sql-unique-query-number=N'

     How many different queries to generate for automatic tests.  For
     example, if you run a `key' test that performs 1000 selects, you
     can use this option with a value of 1000 to run 1000 unique
     queries, or with a value of 50 to perform 50 different selects.
     The default is 10.

   *  `--auto-generate-sql-unique-write-number=N'

     How many different queries to generate for
     `--auto-generate-sql-write-number'.  The default is 10.

   *  `--auto-generate-sql-write-number=N'

     How many row inserts to perform on each thread. The default is 100.

   *  `--burnin'

     Run the full test case in an infinite loop. This option was added
     in MySQL 6.0.3.

   *  `--commit=N'

     How many statements to execute before committing. The default is 0
     (no commits are done).

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--concurrency=N', `-c N'

     The number of clients to simulate when issuing the *Note `SELECT':
     select. statement.

   *  `--create=VALUE'

     The file or string containing the statement to use for creating
     the table.

   *  `--create-schema=VALUE'

     The schema in which to run the tests.

   *  `--csv[=FILE_NAME]'

     Generate output in comma-separated values format. The output goes
     to the named file, or to the standard output if no file is given.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is
     `'d:t:o,/tmp/mysqlslap.trace''.

   *  `--debug-check'

     Print some debugging information when the program exits.

   *  `--debug-info', `-T'

     Print debugging information and memory and CPU usage statistics
     when the program exits.

   *  `--delimiter=STR', `-F STR'

     The delimiter to use in SQL statements supplied in files or via
     command options.

   *  `--delayed-start=N'

     The maximum delay in microseconds. Startup of each thread is
     delayed by a random number of microseconds up to this maximum. The
     default is 0. This option was added in MySQL 6.0.3.

   *  `--detach=N'

     Detach (close and reopen) each connection after each N statements.
     The default is 0 (connections are not detached).

   *  `--engine=ENGINE_NAME', `-e ENGINE_NAME'

     The storage engine to use for creating tables.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--ignore-sql-errors'

     Ignore SQL errors during the test run. By default, errors cause
     *Note `mysqlslap': mysqlslap. to exit. This option was added in
     MySQL 6.0.4.

   *  `--iterations=N', `-i N'

     The number of times to run the tests.

   *  `--label=STR'

     The label to use in printed and CSV output. This option was added
     in MySQL 6.0.3.

   *  `--number-blob-cols=STR',

     The number of *Note `BLOB': blob. columns to use if
     `--auto-generate-sql' is specified.
     `--number-blob-cols=3:1024/2048' would give you 3 *Note `BLOB':
     blob. columns with a random size between 1024 and 2048. This
     option was added in MySQL 6.0.3.

   *  `--number-char-cols=N', `-x N'

     The number of *Note `VARCHAR': char. columns to use if
     `--auto-generate-sql' is specified.

   *  `--number-int-cols=N', `-y N'

     The number of *Note `INT': numeric-types. columns to use if
     `--auto-generate-sql' is specified.

   *  `--number-of-queries=N'

     Limit each client to approximately this number of queries.

   *  `--only-print'

     Do not connect to databases. *Note `mysqlslap': mysqlslap.  only
     prints what it would have done.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the

     `--password' or `-p' option on the command line, you are prompted
     for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--post-query=VALUE'

     The file or string containing the statement to execute after the
     tests have completed. This execution is not counted for timing
     purposes.

   *  `--shared-memory-base-name=NAME'

     On Windows, the shared-memory name to use, for connections made
     via shared memory to a local server. This option applies only if
     the server supports shared-memory connections.

   *  `--post-system=STR'

     The string to execute via `system()' after the tests have
     completed. This execution is not counted for timing purposes.

   *  `--pre-query=VALUE'

     The file or string containing the statement to execute before
     running the tests. This execution is not counted for timing
     purposes. This option was added in MySQL 5.1.18.

   *  `--pre-system=STR'

     The string to execute via `system()' before running the tests.
     This execution is not counted for timing purposes.

   *  `--preserve-schema'

     Preserve the schema from the *Note `mysqlslap': mysqlslap.  run.
     The `--auto-generate-sql' and `--create' options disable this
     option. This option was removed in MySQL 6.0.5.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--query=VALUE', `-q VALUE'

     The file or string containing the *Note `SELECT': select.
     statement to use for retrieving data.

   *  `--set-random-seed=VALUE',

     The seed value for the randomizer.

   *  `--silent', `-s'

     Silent mode. No output.

   *  `--slave'

     Follow master locks for other *Note `mysqlslap': mysqlslap.
     clients. Use this option if you are trying to synchronize around
     one master server with `--lock-directory'
     (http://dev.mysql.com/doc/refman/5.1/en/mysqlslap.html#option_mysqlslap_lock-directory)
     plus NFS.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--timer-length=N'

     The duration in seconds to run each test. Tests that run longer
     are terminated. This option was added in MySQL 6.0.3.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL user name to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.
     This option can be used multiple times to increase the amount of
     information.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: programs-admin-utils,  Next: programs-development,  Prev: programs-client,  Up: programs

4.6 MySQL Administrative and Utility Programs
=============================================

* Menu:

* innochecksum::                 `innochecksum' --- Offline InnoDB File Checksum Utility
* myisam-ftdump::                `myisam_ftdump' --- Display Full-Text Index information
* myisamchk::                    `myisamchk' --- MyISAM Table-Maintenance Utility
* myisamlog::                    `myisamlog' --- Display MyISAM Log File Contents
* myisampack::                   `myisampack' --- Generate Compressed, Read-Only MyISAM Tables
* mysqlaccess::                  `mysqlaccess' --- Client for Checking Access Privileges
* mysqlbackup::                  `mysqlbackup' --- Display Backup Information
* mysqlbinlog::                  `mysqlbinlog' --- Utility for Processing Binary Log Files
* mysqldumpslow::                `mysqldumpslow' --- Summarize Slow Query Log Files
* mysqlhotcopy::                 `mysqlhotcopy' --- A Database Backup Program
* mysql-convert-table-format::   `mysql_convert_table_format' --- Convert Tables to Use a Given Storage Engine
* mysql-find-rows::              `mysql_find_rows' --- Extract SQL Statements from Files
* mysql-fix-extensions::         `mysql_fix_extensions' --- Normalize Table File Name Extensions
* mysql-setpermission::          `mysql_setpermission' --- Interactively Set Permissions in Grant Tables
* mysql-waitpid::                `mysql_waitpid' --- Kill Process and Wait for Its Termination
* mysql-zap::                    `mysql_zap' --- Kill Processes That Match a Pattern


File: manual.info,  Node: innochecksum,  Next: myisam-ftdump,  Prev: programs-admin-utils,  Up: programs-admin-utils

4.6.1 `innochecksum' -- Offline InnoDB File Checksum Utility
------------------------------------------------------------

*Note `innochecksum': innochecksum. prints checksums for `InnoDB' files.

Invoke *Note `innochecksum': innochecksum. like this:

     shell> innochecksum [OPTIONS] FILE_NAME

*Note `innochecksum': innochecksum. supports the options described in
the following list. For options that refer to page numbers, the numbers
are zero-based.

   *  `-c'

     Print a count of the number of pages in the file.

   *  `-d'

     Debug mode; prints checksums for each page.

   *  `-e NUM'

     End at this page number.

   *  `-p NUM'

     Check only this page number.

   *  `-s NUM'

     Start at this page number.

   *  `-v'

     Verbose mode; print a progress indicator every five seconds.


File: manual.info,  Node: myisam-ftdump,  Next: myisamchk,  Prev: innochecksum,  Up: programs-admin-utils

4.6.2 `myisam_ftdump' -- Display Full-Text Index information
------------------------------------------------------------

*Note `myisam_ftdump': myisam-ftdump. displays information about
`FULLTEXT' indexes in `MyISAM' tables. It reads the `MyISAM' index file
directly, so it must be run on the server host where the table is
located

Invoke *Note `myisam_ftdump': myisam-ftdump. like this:

     shell> myisam_ftdump [OPTIONS] TBL_NAME INDEX_NUM

The TBL_NAME argument should be the name of a `MyISAM' table. You can
also specify a table by naming its index file (the file with the `.MYI'
suffix). If you do not invoke *Note `myisam_ftdump': myisam-ftdump. in
the directory where the table files are located, the table or index
file name must be preceded by the path name to the table's database
directory.  Index numbers begin with 0.

Example: Suppose that the `test' database contains a table named
`mytexttablel' that has the following definition:

     CREATE TABLE mytexttable
     (
       id   INT NOT NULL,
       txt  TEXT NOT NULL,
       PRIMARY KEY (id),
       FULLTEXT (txt)
     );

The index on `id' is index 0 and the `FULLTEXT' index on `txt' is index
1. If your working directory is the `test' database directory, invoke
*Note `myisam_ftdump': myisam-ftdump. as follows:

     shell> myisam_ftdump mytexttable 1

If the path name to the `test' database directory is
`/usr/local/mysql/data/test', you can also specify the table name
argument using that path name. This is useful if you do not invoke
*Note `myisam_ftdump': myisam-ftdump. in the database directory:

     shell> myisam_ftdump /usr/local/mysql/data/test/mytexttable 1

*Note `myisam_ftdump': myisam-ftdump. supports the following options:

   *  `--help', `-h' `-?'

     Display a help message and exit.

   *  `--count', `-c'

     Calculate per-word statistics (counts and global weights).

   *  `--dump', `-d'

     Dump the index, including data offsets and word weights.

   *  `--length', `-l'

     Report the length distribution.

   *  `--stats', `-s'

     Report global index statistics. This is the default operation if
     no other operation is specified.

   *  `--verbose', `-v'

     Verbose mode. Print more output about what the program does.


File: manual.info,  Node: myisamchk,  Next: myisamlog,  Prev: myisam-ftdump,  Up: programs-admin-utils

4.6.3 `myisamchk' -- MyISAM Table-Maintenance Utility
-----------------------------------------------------

* Menu:

* myisamchk-general-options::    `myisamchk' General Options
* myisamchk-check-options::      `myisamchk' Check Options
* myisamchk-repair-options::     `myisamchk' Repair Options
* myisamchk-other-options::      Other `myisamchk' Options
* myisamchk-memory::             `myisamchk' Memory Usage

The *Note `myisamchk': myisamchk. utility gets information about your
database tables or checks, repairs, or optimizes them.  *Note
`myisamchk': myisamchk. works with `MyISAM' tables (tables that have
`.MYD' and `.MYI' files for storing data and indexes).

The use of *Note `myisamchk': myisamchk. with partitioned tables is not
supported.

*Caution*:

It is best to make a backup of a table before performing a table repair
operation; under some circumstances the operation might cause data
loss. Possible causes include but are not limited to file system errors.

Invoke *Note `myisamchk': myisamchk. like this:

     shell> myisamchk [OPTIONS] TBL_NAME ...

The OPTIONS specify what you want *Note `myisamchk': myisamchk. to do.
They are described in the following sections. You can also get a list
of options by invoking *Note `myisamchk --help': myisamchk.

With no options, *Note `myisamchk': myisamchk. simply checks your table
as the default operation. To get more information or to tell *Note
`myisamchk': myisamchk. to take corrective action, specify options as
described in the following discussion.

TBL_NAME is the database table you want to check or repair. If you run
*Note `myisamchk': myisamchk.  somewhere other than in the database
directory, you must specify the path to the database directory, because
*Note `myisamchk': myisamchk. has no idea where the database is
located. In fact, *Note `myisamchk': myisamchk. does not actually care
whether the files you are working on are located in a database
directory. You can copy the files that correspond to a database table
into some other location and perform recovery operations on them there.

You can name several tables on the *Note `myisamchk': myisamchk.
command line if you wish. You can also specify a table by naming its
index file (the file with the `.MYI' suffix). This allows you to
specify all tables in a directory by using the pattern `*.MYI'. For
example, if you are in a database directory, you can check all the
`MyISAM' tables in that directory like this:

     shell> myisamchk *.MYI

If you are not in the database directory, you can check all the tables
there by specifying the path to the directory:

     shell> myisamchk /PATH/TO/DATABASE_DIR/*.MYI

You can even check all tables in all databases by specifying a wildcard
with the path to the MySQL data directory:

     shell> myisamchk /PATH/TO/DATADIR/*/*.MYI

The recommended way to quickly check all `MyISAM' tables is:

     shell> myisamchk --silent --fast /PATH/TO/DATADIR/*/*.MYI

If you want to check all `MyISAM' tables and repair any that are
corrupted, you can use the following command:

     shell> myisamchk --silent --force --fast --update-state \
               --key_buffer_size=64M --sort_buffer_size=64M \
               --read_buffer_size=1M --write_buffer_size=1M \
               /PATH/TO/DATADIR/*/*.MYI

This command assumes that you have more than 64MB free. For more
information about memory allocation with *Note `myisamchk': myisamchk,
see *Note myisamchk-memory::.

MySQL Enterprise

For expert advice on checking and repairing tables, subscribe to the
MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Important*:

_You must ensure that no other program is using the tables while you
are running *Note `myisamchk': myisamchk._. The most effective means of
doing so is to shut down the MySQL server while running *Note
`myisamchk': myisamchk, or to lock all tables that *Note `myisamchk':
myisamchk. is being used on.

Otherwise, when you run *Note `myisamchk': myisamchk, it may display
the following error message:

     warning: clients are using or haven't closed the table properly

This means that you are trying to check a table that has been updated
by another program (such as the *Note `mysqld': mysqld. server) that
hasn't yet closed the file or that has died without closing the file
properly, which can sometimes lead to the corruption of one or more
`MyISAM' tables.

If *Note `mysqld': mysqld. is running, you must force it to flush any
table modifications that are still buffered in memory by using *Note
`FLUSH TABLES': flush. You should then ensure that no one is using the
tables while you are running *Note `myisamchk': myisamchk.

However, the easiest way to avoid this problem is to use *Note `CHECK
TABLE': check-table. instead of *Note `myisamchk': myisamchk. to check
tables. See *Note check-table::.

*Note `myisamchk': myisamchk. supports the options in the following
table. It also reads option files and supports the options for
processing them described at *Note option-file-options::.

*`myisamchk' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-analyze    analyze     Analyze the distribution of key              
                        values                                       
-backup     backup      Make a backup of the .MYD file as            
                        file_name-time.BAK                           
-block-search=offsetblock-searchFind the record that a block at the          
                        given offset belongs to                      
-check      check       Check the table for errors                   
-check-only-changedcheck-only-changedCheck only tables that have changed          
                        since the last check                         
-correct-checksumcorrect-checksumCorrect the checksum information             
                        for the table                                
-data-file-length=lendata-file-lengthMaximum length of the data file              
                        (when re-creating data file when             
                        it is full)                                  
-debug[=debug_options]debug       Write a debugging log                        
decode_bits=#decode_bits Decode_bits                                  
-descriptiondescription Print some descriptive information           
                        about the table                              
-extend-checkextend-checkDo a repair that tries to recover            
                        every possible row from the data             
                        file                                         
-extended-checkextended-checkCheck the table very thoroughly              
-fast       fast        Check only tables that haven't been          
                        closed properly                              
-force      force       Do a repair operation automatically          
                        if myisamchk finds any errors  in            
                        the table                                    
-force      force-recoverOverwrite old temporary files. For           
                        use with the -r or -o option                 
ft_max_word_len=#ft_max_word_lenMaximum word length for FULLTEXT             
                        indexes                                      
ft_min_word_len=#ft_min_word_lenMinimum word length for FULLTEXT             
                        indexes                                      
ft_stopword_file=valueft_stopword_fileUse stopwords from this file                 
                        instead of built-in list                     
-HELP                   Display help message and exit                
-help                   Display help message and exit                
-informationinformation Print informational statistics               
                        about the table that is checked              
key_buffer_size=#key_buffer_sizeThe size of the buffer used for              
                        index blocks for MyISAM tables               
-keys-used=valkeys-used   A bit-value that indicates which             
                        indexes to update                            
-max-record-length=lenmax-record-lengthSkip rows larger than the given              
                        length if myisamchk cannot                   
                        allocate memory to hold them                 
-medium-checkmedium-checkDo a check that is faster than an            
                        -extend-check operation                      
myisam_block_size=#myisam_block_sizeBlock size to be used for MyISAM             
                        index pages                                  
-parallel-recoverparallel-recoverUses the same technique as -r and            
                        -n, but creates all the keys in              
                        parallel, using different threads            
                        (beta)                                       
-quick      quick       Achieve a faster repair by not               
                        modifying the data file.                     
read_buffer_size=#read_buffer_sizeEach thread that does a sequential           
                        scan allocates a buffer of this              
                        size for each table it scans                 
-read-only  read-only   Don't mark the table as checked              
-recover    recover     Do a repair that can fix almost any          
                        problem except unique keys  that             
                        aren't unique                                
-safe-recoversafe-recoverDo a repair using an old recovery            
                        method that reads through all  rows          
                        in order and updates all index               
                        trees based on the rows found                
-set-auto-increment[=value]set-auto-incrementForce AUTO_INCREMENT numbering for           
                        new records to start at the  given           
                        value                                        
-set-collation=nameset-collationSpecify the collation to use for             
                        sorting table indexes                        
-silent     silent      Silent mode                                  
sort_buffer_size=#sort_buffer_sizeThe buffer that is allocated when            
                        sorting the index when doing a               
                        REPAIR or when creating indexes              
                        with CREATE INDEX or ALTER TABLE             
-sort-index sort-index  Sort the index tree blocks in                
                        high-low order                               
sort_key_blocks=#sort_key_blockssort_key_blocks                              
-sort-records=#sort-recordsSort records according to a                  
                        particular index                             
-sort-recoversort-recoverForce myisamchk to use sorting to            
                        resolve the keys even if the                 
                        temporary files would be very large          
stats_method=valuestats_methodSpecifies how MyISAM index                   
                        statistics collection code should            
                        treat  NULLs                                 
-tmpdir=pathtmpdir      Path of the directory to be used             
                        for storing temporary files                  
-unpack     unpack      Unpack a table that was packed with          
                        myisampack                                   
-update-stateupdate-stateStore information in the .MYI file           
                        to indicate when the table was               
                        checked and whether the table                
                        crashed                                      
-verbose                Verbose mode                                 
-version                Display version information and exit         
write_buffer_size=#write_buffer_sizeWrite buffer size                            


File: manual.info,  Node: myisamchk-general-options,  Next: myisamchk-check-options,  Prev: myisamchk,  Up: myisamchk

4.6.3.1 `myisamchk' General Options
...................................

The options described in this section can be used for any type of table
maintenance operation performed by *Note `myisamchk': myisamchk. The
sections following this one describe options that pertain only to
specific operations, such as table checking or repairing.

   *  `--help', `-?'

     Display a help message and exit. Options are grouped by type of
     operation.

   *  `--HELP', `-H'

     Display a help message and exit. Options are presented in a single
     list.

   *  `--debug=DEBUG_OPTIONS, -# DEBUG_OPTIONS'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is
     `'d:t:o,/tmp/myisamchk.trace''.

   *  `--silent', `-s'

     Silent mode. Write output only when errors occur. You can use `-s'
     twice (`-ss') to make *Note `myisamchk': myisamchk. very silent.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.
     This can be used with `-d' and `-e'. Use `-v' multiple times
     (`-vv', `-vvv') for even more output.

   *  `--version', `-V'

     Display version information and exit.

   *  `--wait', `-w'

     Instead of terminating with an error if the table is locked, wait
     until the table is unlocked before continuing. If you are running
     *Note `mysqld': mysqld. with external locking disabled, the table
     can be locked only by another *Note `myisamchk': myisamchk.
     command.

You can also set the following variables by using `--VAR_NAME=VALUE'
syntax:

*Variable*                *Default Value*
`decode_bits'             9
`ft_max_word_len'         version-dependent
`ft_min_word_len'         4
`ft_stopword_file'        built-in list
`key_buffer_size'         523264
`myisam_block_size'       1024
`read_buffer_size'        262136
`sort_buffer_size'        2097144
`sort_key_blocks'         16
`stats_method'            nulls_unequal
`write_buffer_size'       262136

The possible *Note `myisamchk': myisamchk. variables and their default
values can be examined with *Note `myisamchk --help': myisamchk.:

`sort_buffer_size' is used when the keys are repaired by sorting keys,
which is the normal case when you use `--recover'.

`key_buffer_size' is used when you are checking the table with
`--extend-check' or when the keys are repaired by inserting keys row by
row into the table (like when doing normal inserts). Repairing through
the key buffer is used in the following cases:

   * You use `--safe-recover'.

   * The temporary files needed to sort the keys would be more than
     twice as big as when creating the key file directly.  This is
     often the case when you have large key values for *Note `CHAR':
     char, *Note `VARCHAR': char, or *Note `TEXT': blob. columns,
     because the sort operation needs to store the complete key values
     as it proceeds. If you have lots of temporary space and you can
     force *Note `myisamchk': myisamchk. to repair by sorting, you can
     use the `--sort-recover' option.

Repairing through the key buffer takes much less disk space than using
sorting, but is also much slower.

If you want a faster repair, set the `key_buffer_size' and
`sort_buffer_size' variables to about 25% of your available memory. You
can set both variables to large values, because only one of them is
used at a time.

`myisam_block_size' is the size used for index blocks.

`stats_method' influences how `NULL' values are treated for index
statistics collection when the `--analyze' option is given. It acts
like the `myisam_stats_method' system variable. For more information,
see the description of `myisam_stats_method' in *Note
server-system-variables::, and *Note myisam-index-statistics::. For
MySQL 6.0, `stats_method' was added in MySQL 5.0.14. For older
versions, the statistics collection method is equivalent to
`nulls_equal'.

The `ft_min_word_len' and `ft_max_word_len' variables are available as
of MySQL 4.0.0. `ft_stopword_file' is available as of MySQL 4.0.19.

`ft_min_word_len' and `ft_max_word_len' indicate the minimum and
maximum word length for `FULLTEXT' indexes.  `ft_stopword_file' names
the stopword file.  These need to be set under the following
circumstances.

If you use *Note `myisamchk': myisamchk. to perform an operation that
modifies table indexes (such as repair or analyze), the `FULLTEXT'
indexes are rebuilt using the default full-text parameter values for
minimum and maximum word length and the stopword file unless you
specify otherwise. This can result in queries failing.

The problem occurs because these parameters are known only by the
server. They are not stored in `MyISAM' index files. To avoid the
problem if you have modified the minimum or maximum word length or the
stopword file in the server, specify the same `ft_min_word_len',
`ft_max_word_len', and `ft_stopword_file' values to *Note `myisamchk':
myisamchk. that you use for *Note `mysqld': mysqld. For example, if you
have set the minimum word length to 3, you can repair a table with
*Note `myisamchk': myisamchk. like this:

     shell> myisamchk --recover --ft_min_word_len=3 TBL_NAME.MYI

To ensure that *Note `myisamchk': myisamchk. and the server use the
same values for full-text parameters, you can place each one in both
the `[mysqld]' and `[myisamchk]' sections of an option file:

     [mysqld]
     ft_min_word_len=3

     [myisamchk]
     ft_min_word_len=3

An alternative to using *Note `myisamchk': myisamchk. is to use the
*Note `REPAIR TABLE': repair-table, *Note `ANALYZE TABLE':
analyze-table, *Note `OPTIMIZE TABLE': optimize-table, or *Note `ALTER
TABLE': alter-table. These statements are performed by the server,
which knows the proper full-text parameter values to use.


File: manual.info,  Node: myisamchk-check-options,  Next: myisamchk-repair-options,  Prev: myisamchk-general-options,  Up: myisamchk

4.6.3.2 `myisamchk' Check Options
.................................

*Note `myisamchk': myisamchk. supports the following options for table
checking operations:

   *  `--check', `-c'

     Check the table for errors. This is the default operation if you
     specify no option that selects an operation type explicitly.

   *  `--check-only-changed', `-C'

     Check only tables that have changed since the last check.

   *  `--extend-check', `-e'

     Check the table very thoroughly. This is quite slow if the table
     has many indexes. This option should only be used in extreme
     cases. Normally, *Note `myisamchk': myisamchk. or *Note `myisamchk
     --medium-check': myisamchk. should be able to determine whether
     there are any errors in the table.

     If you are using `--extend-check' and have plenty of memory,
     setting the `key_buffer_size' variable to a large value helps the
     repair operation run faster.

   *  `--fast', `-F'

     Check only tables that haven't been closed properly.

   *  `--force', `-f'

     Do a repair operation automatically if *Note `myisamchk':
     myisamchk. finds any errors in the table.  The repair type is the
     same as that specified with the `--recover' or `-r' option.

   *  `--information', `-i'

     Print informational statistics about the table that is checked.

   *  `--medium-check', `-m'

     Do a check that is faster than an `--extend-check' operation.
     This finds only 99.99% of all errors, which should be good enough
     in most cases.

   *  `--read-only', `-T'

     Do not mark the table as checked. This is useful if you use *Note
     `myisamchk': myisamchk. to check a table that is in use by some
     other application that does not use locking, such as *Note
     `mysqld': mysqld. when run with external locking disabled.

   *  `--update-state', `-U'

     Store information in the `.MYI' file to indicate when the table
     was checked and whether the table crashed. This should be used to
     get full benefit of the `--check-only-changed' option, but you
     shouldn't use this option if the *Note `mysqld': mysqld. server is
     using the table and you are running it with external locking
     disabled.


File: manual.info,  Node: myisamchk-repair-options,  Next: myisamchk-other-options,  Prev: myisamchk-check-options,  Up: myisamchk

4.6.3.3 `myisamchk' Repair Options
..................................

*Note `myisamchk': myisamchk. supports the following options for table
repair operations:

   *  `--backup', `-B'

     Make a backup of the `.MYD' file as `FILE_NAME-TIME.BAK'

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--correct-checksum'

     Correct the checksum information for the table.

   *  `--data-file-length=LEN, -D LEN'

     Maximum length of the data file (when re-creating data file when
     it is `full').

   *  `--extend-check', `-e'

     Do a repair that tries to recover every possible row from the data
     file. Normally, this also finds a lot of garbage rows. Do not use
     this option unless you are desperate.

   * `--force', `-f'

     Overwrite old intermediate files (files with names like
     `TBL_NAME.TMD') instead of aborting.

   *  `--keys-used=VAL', `-k VAL'

     For *Note `myisamchk': myisamchk, the option value is a bit-value
     that indicates which indexes to update. Each binary bit of the
     option value corresponds to a table index, where the first index
     is bit 0. An option value of 0 disables updates to all indexes,
     which can be used to get faster inserts. Deactivated indexes can
     be reactivated by using *Note `myisamchk -r': myisamchk.

   *  `--no-symlinks', `-l'

     Do not follow symbolic links. Normally *Note `myisamchk':
     myisamchk. repairs the table that a symlink points to. This option
     does not exist as of MySQL 4.0 because versions from 4.0 on do not
     remove symlinks during repair operations.

   *  `--max-record-length=LEN'

     Skip rows larger than the given length if *Note `myisamchk':
     myisamchk. cannot allocate memory to hold them.

   *  `--parallel-recover', `-p'

     Uses the same technique as `-r' and `-n', but creates all the keys
     in parallel, using different threads. _This is beta-quality code.
     Use at your own risk!_

   *  `--quick', `-q'

     Achieve a faster repair by not modifying the data file. You can
     specify this option twice to force *Note `myisamchk': myisamchk.
     to modify the original data file in case of duplicate keys.

   *  `--recover', `-r'

     Do a repair that can fix almost any problem except unique keys
     that are not unique (which is an extremely unlikely error with
     `MyISAM' tables). If you want to recover a table, this is the
     option to try first. You should try `--safe-recover' only if *Note
     `myisamchk': myisamchk. reports that the table cannot be recovered
     using `--recover'. (In the unlikely case that `--recover' fails,
     the data file remains intact.)

     If you have lots of memory, you should increase the value of
     `sort_buffer_size'.

   *  `--safe-recover', `-o'

     Do a repair using an old recovery method that reads through all
     rows in order and updates all index trees based on the rows found.
     This is an order of magnitude slower than `--recover', but can
     handle a couple of very unlikely cases that `--recover' cannot.
     This recovery method also uses much less disk space than
     `--recover'. Normally, you should repair first using `--recover',
     and then with `--safe-recover' only if `--recover' fails.

     If you have lots of memory, you should increase the value of
     `key_buffer_size'.

   *  `--set-character-set=NAME'

     Change the character set used by the table indexes. This option
     was replaced by `--set-collation' in MySQL 5.0.3.

   *  `--set-collation=NAME'

     Specify the collation to use for sorting table indexes. The
     character set name is implied by the first part of the collation
     name.

   *  `--sort-recover', `-n'

     Force *Note `myisamchk': myisamchk. to use sorting to resolve the
     keys even if the temporary files would be very large.

   *  `--tmpdir=PATH', `-t PATH'

     Path of the directory to be used for storing temporary files. If
     this is not set, *Note `myisamchk': myisamchk. uses the value of
     the `TMPDIR' environment variable. `tmpdir' can be set to a list of
     directory paths that are used successively in round-robin fashion
     for creating temporary files. The separator character between
     directory names is the colon (``:'') on Unix and the semicolon
     (``;'') on Windows, NetWare, and OS/2.

   *  `--unpack', `-u'

     Unpack a table that was packed with *Note `myisampack': myisampack.


File: manual.info,  Node: myisamchk-other-options,  Next: myisamchk-memory,  Prev: myisamchk-repair-options,  Up: myisamchk

4.6.3.4 Other `myisamchk' Options
.................................

*Note `myisamchk': myisamchk. supports the following options for
actions other than table checks and repairs:

   *  `--analyze', `-a'

     Analyze the distribution of key values. This improves join
     performance by enabling the join optimizer to better choose the
     order in which to join the tables and which indexes it should use.
     To obtain information about the key distribution, use a *Note
     `myisamchk --description --verbose TBL_NAME': myisamchk.  command
     or the `SHOW INDEX FROM TBL_NAME' statement.

     MySQL Enterprise

     For expert advice on optimizing tables, subscribe to the MySQL
     Enterprise Monitor. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--block-search=OFFSET', `-b OFFSET'

     Find the record that a block at the given offset belongs to.

   *  `--description', `-d'

     Print some descriptive information about the table.

   *  `--set-auto-increment[=VALUE]', `-A[VALUE]'

     Force `AUTO_INCREMENT' numbering for new records to start at the
     given value (or higher, if there are existing records with
     `AUTO_INCREMENT' values this large). If VALUE is not specified,
     `AUTO_INCREMENT' numbers for new records begin with the largest
     value currently in the table, plus one.

   *  `--sort-index', `-S'

     Sort the index tree blocks in high-low order. This optimizes seeks
     and makes table scans that use indexes faster.

   *  `--sort-records=N', `-R N'

     Sort records according to a particular index. This makes your data
     much more localized and may speed up range-based *Note `SELECT':
     select. and `ORDER BY' operations that use this index. (The first
     time you use this option to sort a table, it may be very slow.)
     To determine a table's index numbers, use *Note `SHOW INDEX':
     show-index, which displays a table's indexes in the same order that
     *Note `myisamchk': myisamchk. sees them. Indexes are numbered
     beginning with 1.

     If keys are not packed (`PACK_KEYS=0'), they have the same length,
     so when *Note `myisamchk': myisamchk. sorts and moves records, it
     just overwrites record offsets in the index. If keys are packed
     (`PACK_KEYS=1'), *Note `myisamchk': myisamchk. must unpack key
     blocks first, then re-create indexes and pack the key blocks
     again. (In this case, re-creating indexes is faster than updating
     offsets for each index.)


File: manual.info,  Node: myisamchk-memory,  Prev: myisamchk-other-options,  Up: myisamchk

4.6.3.5 `myisamchk' Memory Usage
................................

Memory allocation is important when you run *Note `myisamchk':
myisamchk. *Note `myisamchk': myisamchk. uses no more memory than its
memory-related variables are set to. If you are going to use *Note
`myisamchk': myisamchk. on very large tables, you should first decide
how much memory you want it to use. The default is to use only about
3MB to perform repairs. By using larger values, you can get *Note
`myisamchk': myisamchk. to operate faster. For example, if you have
more than 32MB RAM, you could use options such as these (in addition to
any other options you might specify):

     shell> myisamchk --sort_buffer_size=16M --key_buffer_size=16M \
                --read_buffer_size=1M --write_buffer_size=1M ...

Using `--sort_buffer_size=16M' should probably be enough for most cases.

Be aware that *Note `myisamchk': myisamchk. uses temporary files in
`TMPDIR'. If `TMPDIR' points to a memory file system, you may easily
get out of memory errors. If this happens, run *Note `myisamchk':
myisamchk. with the `--tmpdir=PATH' option to specify some directory
located on a file system that has more space.

When repairing, *Note `myisamchk': myisamchk. also needs a lot of disk
space:

   * Double the size of the data file (the original file and a copy).
     This space is not needed if you do a repair with `--quick'; in
     this case, only the index file is re-created. _This space must be
     available on the same file system as the original data file_, as
     the copy is created in the same directory as the original.

   * Space for the new index file that replaces the old one. The old
     index file is truncated at the start of the repair operation, so
     you usually ignore this space. This space must be available on the
     same file system as the original data file.

   * When using `--recover' or `--sort-recover' (but not when using
     `--safe-recover'), you need space for a sort buffer. The following
     formula yields the amount of space required:

          (LARGEST_KEY + ROW_POINTER_LENGTH) x NUMBER_OF_ROWS x 2

     You can check the length of the keys and the `row_pointer_length'
     with *Note `myisamchk -dv TBL_NAME': myisamchk. This space is
     allocated in the temporary directory (specified by `TMPDIR' or
     `--tmpdir=PATH').

If you have a problem with disk space during repair, you can try
`--safe-recover' instead of `--recover'.


File: manual.info,  Node: myisamlog,  Next: myisampack,  Prev: myisamchk,  Up: programs-admin-utils

4.6.4 `myisamlog' -- Display MyISAM Log File Contents
-----------------------------------------------------

*Note `myisamlog': myisamlog. processes the contents of a `MyISAM' log
file.

Invoke *Note `myisamlog': myisamlog. like this:

     shell> myisamlog [OPTIONS] [LOG_FILE [TBL_NAME] ...]
     shell> isamlog [OPTIONS] [LOG_FILE [TBL_NAME] ...]

The default operation is update (`-u'). If a recovery is done (`-r'),
all writes and possibly updates and deletes are done and errors are
only counted. The default log file name is `myisam.log' for *Note
`myisamlog': myisamlog. and `isam.log' for `isamlog' if no LOG_FILE
argument is given. If tables are named on the command line, only those
tables are updated.

*Note `myisamlog': myisamlog. supports the following options:

   *  `-?', `-I'

     Display a help message and exit.

   * `-c N'

     Execute only N commands.

   *  `-f N'

     Specify the maximum number of open files.

   *  `-i'

     Display extra information before exiting.

   *  `-o OFFSET'

     Specify the starting offset.

   *  `-p N'

     Remove N components from path.

   *  `-r'

     Perform a recovery operation.

   *  `-R RECORD_POS_FILE RECORD_POS'

     Specify record position file and record position.

   *  `-u'

     Perform an update operation.

   *  `-v'

     Verbose mode. Print more output about what the program does.  This
     option can be given multiple times to produce more and more output.

   *  `-w WRITE_FILE'

     Specify the write file.

   *  `-V'

     Display version information.


File: manual.info,  Node: myisampack,  Next: mysqlaccess,  Prev: myisamlog,  Up: programs-admin-utils

4.6.5 `myisampack' -- Generate Compressed, Read-Only MyISAM Tables
------------------------------------------------------------------

The *Note `myisampack': myisampack. utility compresses `MyISAM' tables.
*Note `myisampack': myisampack.  works by compressing each column in
the table separately.  Usually, *Note `myisampack': myisampack. packs
the data file 40%-70%.

When the table is used later, the server reads into memory the
information needed to decompress columns. This results in much better
performance when accessing individual rows, because you only have to
uncompress exactly one row.

MySQL uses `mmap()' when possible to perform memory mapping on
compressed tables. If `mmap()' does not work, MySQL falls back to
normal read/write file operations.

Please note the following:

   * If the *Note `mysqld': mysqld. server was invoked with external
     locking disabled, it is not a good idea to invoke *Note
     `myisampack': myisampack. if the table might be updated by the
     server during the packing process. It is safest to compress tables
     with the server stopped.

   * After packing a table, it becomes read only. This is generally
     intended (such as when accessing packed tables on a CD). Allowing
     writes to a packed table is on our TODO list, but with low
     priority.

Invoke *Note `myisampack': myisampack. like this:

     shell> myisampack [OPTIONS] FILE_NAME ...

Each file name argument should be the name of an index (`.MYI') file.
If you are not in the database directory, you should specify the path
name to the file. It is permissible to omit the `.MYI' extension.

After you compress a table with *Note `myisampack': myisampack, you
should use *Note `myisamchk -rq': myisamchk. to rebuild its indexes.
*Note myisamchk::.

*Note `myisampack': myisampack. supports the options in the following
list. It also reads option files and supports the options for
processing them described at *Note option-file-options::.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--backup', `-b'

     Make a backup of each table's data file using the name
     `TBL_NAME.OLD'.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is `'d:t:o''.

   *  `--force', `-f'

     Produce a packed table even if it becomes larger than the original
     or if the intermediate file from an earlier invocation of *Note
     `myisampack': myisampack. exists.  (*Note `myisampack':
     myisampack. creates an intermediate file named `TBL_NAME.TMD' in
     the database directory while it compresses the table. If you kill
     *Note `myisampack': myisampack, the `.TMD' file might not be
     deleted.)  Normally, *Note `myisampack': myisampack. exits with an
     error if it finds that `TBL_NAME.TMD' exists. With `--force',
     *Note `myisampack': myisampack. packs the table anyway.

   *  `--join=BIG_TBL_NAME', `-j BIG_TBL_NAME'

     Join all tables named on the command line into a single packed
     table BIG_TBL_NAME. All tables that are to be combined _must_ have
     identical structure (same column names and types, same indexes,
     and so forth).

     BIG_TBL_NAME must not exist prior to the join operation. All
     source tables named on the command line to be merged into
     BIG_TBL_NAME must exist. The source tables are read for the join
     operation but not modified. The join operation does not create a
     `.frm' file for BIG_TBL_NAME, so after the join operation
     finishes, copy the `.frm' file from one of the source tables and
     name it `BIG_TBL_NAME.frm'.

   *  `--silent', `-s'

     Silent mode. Write output only when errors occur.

   *  `--test', `-t'

     Do not actually pack the table, just test packing it.

   *  `--tmpdir=PATH', `-T PATH'

     Use the named directory as the location where *Note `myisampack':
     myisampack. creates temporary files.

   *  `--verbose', `-v'

     Verbose mode. Write information about the progress of the packing
     operation and its result.

   *  `--version', `-V'

     Display version information and exit.

   *  `--wait', `-w'

     Wait and retry if the table is in use. If the *Note `mysqld':
     mysqld. server was invoked with external locking disabled, it is
     not a good idea to invoke *Note `myisampack': myisampack. if the
     table might be updated by the server during the packing process.

The following sequence of commands illustrates a typical table
compression session:

     shell> ls -l station.*
     -rw-rw-r--   1 monty    my         994128 Apr 17 19:00 station.MYD
     -rw-rw-r--   1 monty    my          53248 Apr 17 19:00 station.MYI
     -rw-rw-r--   1 monty    my           5767 Apr 17 19:00 station.frm

     shell> myisamchk -dvv station

     MyISAM file:     station
     Isam-version:  2
     Creation time: 1996-03-13 10:08:58
     Recover time:  1997-02-02  3:06:43
     Data records:              1192  Deleted blocks:              0
     Datafile parts:            1192  Deleted data:                0
     Datafile pointer (bytes):     2  Keyfile pointer (bytes):     2
     Max datafile length:   54657023  Max keyfile length:   33554431
     Recordlength:               834
     Record format: Fixed length

     table description:
     Key Start Len Index   Type                 Root  Blocksize    Rec/key
     1   2     4   unique  unsigned long        1024       1024          1
     2   32    30  multip. text                10240       1024          1

     Field Start Length Type
     1     1     1
     2     2     4
     3     6     4
     4     10    1
     5     11    20
     6     31    1
     7     32    30
     8     62    35
     9     97    35
     10    132   35
     11    167   4
     12    171   16
     13    187   35
     14    222   4
     15    226   16
     16    242   20
     17    262   20
     18    282   20
     19    302   30
     20    332   4
     21    336   4
     22    340   1
     23    341   8
     24    349   8
     25    357   8
     26    365   2
     27    367   2
     28    369   4
     29    373   4
     30    377   1
     31    378   2
     32    380   8
     33    388   4
     34    392   4
     35    396   4
     36    400   4
     37    404   1
     38    405   4
     39    409   4
     40    413   4
     41    417   4
     42    421   4
     43    425   4
     44    429   20
     45    449   30
     46    479   1
     47    480   1
     48    481   79
     49    560   79
     50    639   79
     51    718   79
     52    797   8
     53    805   1
     54    806   1
     55    807   20
     56    827   4
     57    831   4

     shell> myisampack station.MYI
     Compressing station.MYI: (1192 records)
     - Calculating statistics

     normal:     20  empty-space:   16  empty-zero:     12  empty-fill:  11
     pre-space:   0  end-space:     12  table-lookups:   5  zero:         7
     Original trees:  57  After join: 17
     - Compressing file
     87.14%
     Remember to run myisamchk -rq on compressed tables

     shell> ls -l station.*
     -rw-rw-r--   1 monty    my         127874 Apr 17 19:00 station.MYD
     -rw-rw-r--   1 monty    my          55296 Apr 17 19:04 station.MYI
     -rw-rw-r--   1 monty    my           5767 Apr 17 19:00 station.frm

     shell> myisamchk -dvv station

     MyISAM file:     station
     Isam-version:  2
     Creation time: 1996-03-13 10:08:58
     Recover time:  1997-04-17 19:04:26
     Data records:               1192  Deleted blocks:              0
     Datafile parts:             1192  Deleted data:                0
     Datafile pointer (bytes):      3  Keyfile pointer (bytes):     1
     Max datafile length:    16777215  Max keyfile length:     131071
     Recordlength:                834
     Record format: Compressed

     table description:
     Key Start Len Index   Type                 Root  Blocksize    Rec/key
     1   2     4   unique  unsigned long       10240       1024          1
     2   32    30  multip. text                54272       1024          1

     Field Start Length Type                         Huff tree  Bits
     1     1     1      constant                             1     0
     2     2     4      zerofill(1)                          2     9
     3     6     4      no zeros, zerofill(1)                2     9
     4     10    1                                           3     9
     5     11    20     table-lookup                         4     0
     6     31    1                                           3     9
     7     32    30     no endspace, not_always              5     9
     8     62    35     no endspace, not_always, no empty    6     9
     9     97    35     no empty                             7     9
     10    132   35     no endspace, not_always, no empty    6     9
     11    167   4      zerofill(1)                          2     9
     12    171   16     no endspace, not_always, no empty    5     9
     13    187   35     no endspace, not_always, no empty    6     9
     14    222   4      zerofill(1)                          2     9
     15    226   16     no endspace, not_always, no empty    5     9
     16    242   20     no endspace, not_always              8     9
     17    262   20     no endspace, no empty                8     9
     18    282   20     no endspace, no empty                5     9
     19    302   30     no endspace, no empty                6     9
     20    332   4      always zero                          2     9
     21    336   4      always zero                          2     9
     22    340   1                                           3     9
     23    341   8      table-lookup                         9     0
     24    349   8      table-lookup                        10     0
     25    357   8      always zero                          2     9
     26    365   2                                           2     9
     27    367   2      no zeros, zerofill(1)                2     9
     28    369   4      no zeros, zerofill(1)                2     9
     29    373   4      table-lookup                        11     0
     30    377   1                                           3     9
     31    378   2      no zeros, zerofill(1)                2     9
     32    380   8      no zeros                             2     9
     33    388   4      always zero                          2     9
     34    392   4      table-lookup                        12     0
     35    396   4      no zeros, zerofill(1)               13     9
     36    400   4      no zeros, zerofill(1)                2     9
     37    404   1                                           2     9
     38    405   4      no zeros                             2     9
     39    409   4      always zero                          2     9
     40    413   4      no zeros                             2     9
     41    417   4      always zero                          2     9
     42    421   4      no zeros                             2     9
     43    425   4      always zero                          2     9
     44    429   20     no empty                             3     9
     45    449   30     no empty                             3     9
     46    479   1                                          14     4
     47    480   1                                          14     4
     48    481   79     no endspace, no empty               15     9
     49    560   79     no empty                             2     9
     50    639   79     no empty                             2     9
     51    718   79     no endspace                         16     9
     52    797   8      no empty                             2     9
     53    805   1                                          17     1
     54    806   1                                           3     9
     55    807   20     no empty                             3     9
     56    827   4      no zeros, zerofill(2)                2     9
     57    831   4      no zeros, zerofill(1)                2     9

*Note `myisampack': myisampack. displays the following kinds of
information:

   * `normal'

     The number of columns for which no extra packing is used.

   * `empty-space'

     The number of columns containing values that are only spaces.
     These occupy one bit.

   * `empty-zero'

     The number of columns containing values that are only binary
     zeros. These occupy one bit.

   * `empty-fill'

     The number of integer columns that do not occupy the full byte
     range of their type. These are changed to a smaller type. For
     example, a *Note `BIGINT': numeric-types.  column (eight bytes)
     can be stored as a *Note `TINYINT': numeric-types. column (one
     byte) if all its values are in the range from `-128' to `127'.

   * `pre-space'

     The number of decimal columns that are stored with leading spaces.
     In this case, each value contains a count for the number of
     leading spaces.

   * `end-space'

     The number of columns that have a lot of trailing spaces. In this
     case, each value contains a count for the number of trailing
     spaces.

   * `table-lookup'

     The column had only a small number of different values, which were
     converted to an *Note `ENUM': enum. before Huffman compression.

   * `zero'

     The number of columns for which all values are zero.

   * `Original trees'

     The initial number of Huffman trees.

   * `After join'

     The number of distinct Huffman trees left after joining trees to
     save some header space.

After a table has been compressed, *Note `myisamchk -dvv': myisamchk.
prints additional information about each column:

   * `Type'

     The data type. The value may contain any of the following
     descriptors:

        * `constant'

          All rows have the same value.

        * `no endspace'

          Do not store endspace.

        * `no endspace, not_always'

          Do not store endspace and do not do endspace compression for
          all values.

        * `no endspace, no empty'

          Do not store endspace. Do not store empty values.

        * `table-lookup'

          The column was converted to an *Note `ENUM': enum.

        * `zerofill(N)'

          The most significant N bytes in the value are always 0 and
          are not stored.

        * `no zeros'

          Do not store zeros.

        * `always zero'

          Zero values are stored using one bit.

   * `Huff tree'

     The number of the Huffman tree associated with the column.

   * `Bits'

     The number of bits used in the Huffman tree.

After you run *Note `myisampack': myisampack, you must run *Note
`myisamchk': myisamchk. to re-create any indexes. At this time, you can
also sort the index blocks and create statistics needed for the MySQL
optimizer to work more efficiently:

     shell> myisamchk -rq --sort-index --analyze TBL_NAME.MYI

After you have installed the packed table into the MySQL database
directory, you should execute *Note `mysqladmin flush-tables':
mysqladmin. to force *Note `mysqld': mysqld. to start using the new
table.

To unpack a packed table, use the `--unpack' option to *Note
`myisamchk': myisamchk.


File: manual.info,  Node: mysqlaccess,  Next: mysqlbackup,  Prev: myisampack,  Up: programs-admin-utils

4.6.6 `mysqlaccess' -- Client for Checking Access Privileges
------------------------------------------------------------

*Note `mysqlaccess': mysqlaccess. is a diagnostic tool that Yves
Carlier has provided for the MySQL distribution. It checks the access
privileges for a host name, user name, and database combination. Note
that *Note `mysqlaccess': mysqlaccess. checks access using only the
`user', `db', and `host' tables. It does not check table, column, or
routine privileges specified in the `tables_priv', `columns_priv', or
`procs_priv' tables.

Invoke *Note `mysqlaccess': mysqlaccess. like this:

     shell> mysqlaccess [HOST_NAME [USER_NAME [DB_NAME]]] [OPTIONS]

*Note `mysqlaccess': mysqlaccess. supports the following options:

*`mysqlaccess' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-brief      brief       Generate reports in single-line              
                        tabular format                               
-commit     commit      Copy the new access privileges from          
                        the temporary tables to the                  
                        original grant tables                        
-copy       copy        Reload the temporary grant tables            
                        from original ones                           
-db=db_name db          Specify the database name                    
-debug=#    debug       Specify the debug level                      
-help                   Display help message and exit                
-host=host_namehost        Connect to the MySQL server on the           
                        given host                                   
-howto      howto       Display some examples that show how          
                        to use mysqlaccess                           
-old_server old_server  Assume that the server is an old             
                        MySQL server (prior to MySQL  3.21)          
-password[=password]password    The password to use when connecting          
                        to the server                                
-plan       plan        Display suggestions and ideas for            
                        future releases                              
-preview    preview     Show the privilege differences               
                        after making changes to the                  
                        temporary grant tables                       
-relnotes   relnotes    Display the release notes                    
-rhost=host_namerhost       Connect to the MySQL server on the           
                        given host                                   
-rollback   rollback    Undo the most recent changes to the          
                        temporary grant tables.                      
-spassword[=password]spassword   The password to use when connecting          
                        to the server as the superuser               
-superuser=user_namesuperuser   Specify the user name for                    
                        connecting as the superuser                  
-table      table       Generate reports in table format             
-user=user_name,user        The MySQL user name to use when              
                        connecting                                   
-version                Display version information and exit         

   *  `--help', `-?'

     Display a help message and exit.

   *  `--brief', `-b'

     Generate reports in single-line tabular format.

   *  `--commit'

     Copy the new access privileges from the temporary tables to the
     original grant tables. The grant tables must be flushed for the
     new privileges to take effect. (For example, execute a *Note
     `mysqladmin reload': mysqladmin. command.)

   *  `--copy'

     Reload the temporary grant tables from original ones.

   *  `--db=DB_NAME', `-d DB_NAME'

     Specify the database name.

   *  `--debug=N'

     Specify the debug level. N can be an integer from 0 to 3.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     The host name to use in the access privileges.

   *  `--howto'

     Display some examples that show how to use *Note `mysqlaccess':
     mysqlaccess.

   *  `--old_server'

     Assume that the server is an old MySQL server (before MySQL 3.21)
     that does not yet know how to handle full `WHERE' clauses.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you omit the
     PASSWORD value following the `--password' or `-p' option on the
     command line, you are prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--plan'

     Display suggestions and ideas for future releases.

   *  `--preview'

     Show the privilege differences after making changes to the
     temporary grant tables.

   *  `--relnotes'

     Display the release notes.

   *  `--rhost=HOST_NAME', `-H HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--rollback'

     Undo the most recent changes to the temporary grant tables.

   *  `--spassword[=PASSWORD]', `-P[PASSWORD]'

     The password to use when connecting to the server as the
     superuser. If you omit the PASSWORD value following the
     `--password' or `-p' option on the command line, you are prompted
     for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--superuser=USER_NAME', `-U USER_NAME'

     Specify the user name for connecting as the superuser.

   *  `--table', `-t'

     Generate reports in table format.

   *  `--user=USER_NAME', `-u USER_NAME'

     The user name to use in the access privileges.

   *  `--version', `-v'

     Display version information and exit.

If your MySQL distribution is installed in some non-standard location,
you must change the location where *Note `mysqlaccess': mysqlaccess.
expects to find the *Note `mysql': mysql. client. Edit the
`mysqlaccess' script at approximately line 18. Search for a line that
looks like this:

     $MYSQL     = '/usr/local/bin/mysql';    # path to mysql executable

Change the path to reflect the location where *Note `mysql': mysql.
actually is stored on your system. If you do not do this, a `Broken
pipe' error will occur when you run *Note `mysqlaccess': mysqlaccess.


File: manual.info,  Node: mysqlbackup,  Next: mysqlbinlog,  Prev: mysqlaccess,  Up: programs-admin-utils

4.6.7 `mysqlbackup' -- Display Backup Information
-------------------------------------------------

*Note `mysqlbackup': mysqlbackup. displays information from backup
images created by the *Note `BACKUP DATABASE': backup-database.
statement. This program was added in MySQL 6.0.11.

*Note `mysqlbackup': mysqlbackup. has these capabilities:

   * List the objects contained in the backup image or information
     about the objects

   * Display the metadata (SQL statements to create objects in the
     backup image)

   * Search the backup image for a particular object

Invoke *Note `mysqlbackup': mysqlbackup. like this:

     shell> mysqlbackup [OPTIONS] BACKUP_IMAGE_FILE

With no options, *Note `mysqlbackup': mysqlbackup. displays a short
summary about the backup image:

     shell> mysqlbackup /tmp/test.bak
     Image path:          '/tmp/test.bak'
     Image size:          12305 bytes
     Image compression:   none
     Image version:       1
     Creation time:       2009-04-08 18:08:43 UTC
     Server version:      6.0.11 (6.0.11-alpha)
     Server byte order:   little-endian

*Note `mysqlbackup': mysqlbackup. supports the following options.  It
also reads option files and supports the options for processing them
described at *Note option-file-options::.

*`mysqlbackup' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-all        all         Display everything except snapshots  6.0.11  
                        and data-chunks                              
-catalog-detailscatalog-detailsDisplay details of the database      6.0.11  
                        objects catalog                              
-catalog-summarycatalog-summaryDisplay summary of the database      6.0.11  
                        objects catalog                              
-data-chunksdata-chunks Display length of each data chunk    6.0.11  
                        contained in the backup image                
-data-totalsdata-totals Display length of data contained in  6.0.11  
                        the backup image for each  object            
-debug[=debug_options]debug       Write a debugging log                6.0.11  
-exact      exact       Display exact number of bytes        6.0.11  
                        instead of KB, MB, GB units                  
-help                   Display help message and exit        6.0.11  
-image-orderimage-order Display catalog items and metadata   6.0.11  
                        in the order of the backup  image            
-metadata-extrametadata-extraDisplay extra metadata for the       6.0.11  
                        database objects                             
-metadata-statementsmetadata-statementsDisplay SQL statements that create   6.0.11  
                        the database objects                         
-open_files_limit=#open_files_limitHow many file descriptors to reserve 6.0.11  
-search=namesearch      Search for object in the backup      6.0.11  
                        image                                        
-snapshots  snapshots   Display information about snapshots  6.0.11  
                        contained in the backup image                
-summary    summary     Display summary information from     6.0.11  
                        end of the backup image                      
-verbose                Verbose mode                         6.0.11  
-version                Display version information and exit 6.0.11  

   *  `--help', `-?'

     Display a help message and exit.

   *  `--all'

     Display everything except snapshots and data-chunks.

   *  `--catalog-details'

     Display the details of the database objects catalog.

   *  `--catalog-summary'

     Display summary of the database objects catalog.

   *  `--data-chunks'

     Display the length of each data chunk contained in the backup
     image.

   *  `--data-totals'

     Display the data length for each object contained in the backup
     image.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is
     `'d:t:o,/tmp/mysqlbackup.trace''.

   *  `--exact'

     Display lengths using the exact number of bytes instead of
     multiplier units such as KB, MB, and GB.

   *  `--image-order'

     Display catalog items and metadata in the order of the backup
     image.

   *  `--metadata-extra'

     Display extra metadata for the database objects.

   *  `--metadata-statements'

     Display SQL statements that create the database objects in the
     backup image.

   *  `--open_files_limit=COUNT'

     Specify how many file descriptors to reserve.

   *  `--search=NAME'

     Search for the given object in the backup image. The name can be
     OBJECT to find a global object or DATABASE.OBJECT to find a
     per-database object. Quoting of database and/or object with `"',
     `'', or ``' is allowed. The wildcard characters `'%'' and `'_'' are
     available and have the same effect as for the `LIKE' operator. Use
     this option with the `--metadata-*' options to see metadata.

   *  `--snapshots'

     Display information about snapshots contained in the backup image.

   *  `--summary'

     Display a summary information from end of the backup image.

   *  `--verbose', `-v'

     Verbose mode. Include more information about the backup image in
     program output.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: mysqlbinlog,  Next: mysqldumpslow,  Prev: mysqlbackup,  Up: programs-admin-utils

4.6.8 `mysqlbinlog' -- Utility for Processing Binary Log Files
--------------------------------------------------------------

* Menu:

* mysqlbinlog-hexdump::          `mysqlbinlog' Hex Dump Format
* mysqlbinlog-row-events::       `mysqlbinlog' Row Event Display

The server's binary log consists of files containing `events' that
describe modifications to database contents. The server writes these
files in binary format. To display their contents in text format, use
the *Note `mysqlbinlog': mysqlbinlog. utility. You can also use *Note
`mysqlbinlog': mysqlbinlog. to display the contents of relay log files
written by a slave server in a replication setup because relay logs
have the same format as binary logs. The binary log and relay log are
discussed further in *Note binary-log::, and *Note slave-logs::.

Invoke *Note `mysqlbinlog': mysqlbinlog. like this:

     shell> mysqlbinlog [OPTIONS] LOG_FILE ...

For example, to display the contents of the binary log file named
`binlog.000003', use this command:

     shell> mysqlbinlog binlog.0000003

The output includes events contained in `binlog.000003'. Event
information includes the statement, the ID of the server on which it
was executed, the timestamp when the statement was executed, how much
time it took, and so forth.

The output from *Note `mysqlbinlog': mysqlbinlog. can be re-executed
(for example, by using it as input to *Note `mysql': mysql.) to reapply
the statements in the log.  This is useful for recovery operations
after a server crash. For other usage examples, see the discussion
later in this section.

Normally, you use *Note `mysqlbinlog': mysqlbinlog. to read binary log
files directly and apply them to the local MySQL server. It is also
possible to read binary logs from a remote server by using the
`--read-from-remote-server' option. When you read remote binary logs,
the connection parameter options can be given to indicate how to
connect to the server. These options are `--host', `--password',
`--port', `--protocol', `--socket', and `--user'; they are ignored
except when you also use the `--read-from-remote-server' option.

*Note `mysqlbinlog': mysqlbinlog. supports the following options.  It
also reads option files and supports the options for processing them
described at *Note option-file-options::.

*`mysqlbinlog' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-base64-output[=value]base64-outputPrint binary log entries using               
                        base-64 encoding                             
-character-sets-dir=pathcharacter-sets-dirThe directory where character sets           
                        are installed                                
-database=db_namedatabase    List entries for just this database          
-debug[=debug_options]debug       Write a debugging log                        
-debug-checkdebug-check Print debugging information when             
                        the program exits                            
-debug-info debug-info  Print debugging information, memory          
                        and CPU statistics when the                  
                        program exits                                
-disable-log-bindisable-log-binDisable binary logging                       
-force-read force-read  If mysqlbinlog reads a binary log            
                        event that it does not  recognize,           
                        it prints a warning                          
-help                   Display help message and exit                
-hexdump    hexdump     Display a hex dump of the log in             
                        comments                                     
-host=host_namehost        Connect to the MySQL server on the           
                        given host                                   
-local-load=pathlocal-load  Prepare local temporary files for            
                        LOAD DATA INFILE in the  specified           
                        directory                                    
-offset=#   offset      Skip the first N entries in the log          
-password[=password]password    The password to use when connecting          
                        to the server                                
-port=port_numport        The TCP/IP port number to use for            
                        the connection                               
-protocol=typeprotocol    The connection protocol to use               
-read-from-remote-serverread-from-remote-serverRead the binary log from a MySQL             
                        server rather than reading a  local          
                        log file                                     
-result-file=nameresult-file Direct output to the given file              
-server-id=idserver-id   Extract only those events created            
                        by the server having the given               
                        server ID                                    
-set-charset=charset_nameset-charset Add a SET NAMES charset_name                 
                        statement to the output                      
-short-form short-form  Display only the statements                  
                        contained in the log                         
-socket=pathsocket      For connections to localhost                 
-start-datetime=datetimestart-datetimeStart reading the binary log at the          
                        first event having a timestamp               
                        equal to or later than the datetime          
                        argument                                     
-start-position=#start-positionStart reading the binary log at the          
                        first event having a position                
                        equal to or greater than the                 
                        argument                                     
-stop-datetime=datetimestop-datetimeStop reading the binary log at the           
                        first event having a timestamp               
                        equal to or greater than the                 
                        datetime argument                            
-stop-position=#stop-positionStop reading the binary log at the           
                        first event having a position                
                        equal to or greater than the                 
                        argument                                     
-to-last-logto-last-log Do not stop at the end of the                
                        requested binary log from a MySQL            
                        server, but rather continue                  
                        printing until the end of the last           
                        binary log                                   
-user=user_name,user        The MySQL user name to use when              
                        connecting to the server                     
-verbose                Reconstruct row events as SQL        6.0.7   
                        statements                                   
-version                Display version information and exit         

   *  `--help', `-?'

     Display a help message and exit.

   *  `--base64-output[=VALUE]'

     This option determines when events should be displayed encoded as
     base-64 strings using *Note `BINLOG': binlog. statements. The
     option has these allowable values (not case sensitive):

        * `AUTO' ("automatic") or `UNSPEC' ("unspecified") displays
          *Note `BINLOG': binlog. statements automatically when
          necessary (that is, for format description events and row
          events). This is the default if no `--base64-output' option
          is given.

          *Note*:

          Automatic *Note `BINLOG': binlog.  display is the only safe
          behavior if you intend to use the output of *Note
          `mysqlbinlog': mysqlbinlog. to re-execute binary log file
          contents. The other option values are intended only for
          debugging or testing purposes because they may produce output
          that does not include all events in executable form.

        * `ALWAYS' displays *Note `BINLOG': binlog. statements whenever
          possible. This is the implied value if the option is given as
          `--base64-output' without a value.

        * `NEVER' causes *Note `BINLOG': binlog. statements not to be
          displayed. *Note `mysqlbinlog': mysqlbinlog. exits with an
          error if a row event is found that must be displayed using
          *Note `BINLOG': binlog.

        * `DECODE-ROWS' specifies to *Note `mysqlbinlog': mysqlbinlog.
          that you intend for row events to be decoded and displayed as
          commented SQL statements by also specifying the `--verbose'
          option.  Like `NEVER', `DECODE-ROWS' suppresses display of
          *Note `BINLOG': binlog. statements, but unlike `NEVER', it
          does not exit with an error if a row event is found.

     Before MySQL 6.0.4, the `--base64-output' option was boolean, to
     be given as `--base64-output' or `--skip-base64-output' (with the
     sense of `AUTO' or `NEVER'). The option values described in the
     preceding list may be used as of MySQL 6.0.4, with the exception
     of `UNSPEC' and `DECODE-ROWS', which are available as of MySQL
     6.0.7.

     For examples that show the effect of `--base64-output' and
     `--verbose' on row event output, see *Note
     mysqlbinlog-row-events::.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--database=DB_NAME', `-d DB_NAME'

     List entries for just this database (local log only). You can only
     specify one database with this option - if you specify multiple
     `--database' options, only the last one is used. This option forces
     *Note `mysqlbinlog': mysqlbinlog. to output entries from the
     binary log where the default database (that is, the one selected
     by *Note `USE': use.) is DB_NAME. Note that this does not
     replicate cross-database statements such as `UPDATE
     SOME_DB.SOME_TABLE SET foo='bar'' while having selected a different
     database or no database.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is
     `'d:t:o,/tmp/mysqlbinlog.trace''.

   *  `--debug-check'

     Print some debugging information when the program exits.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits.

   *  `--disable-log-bin', `-D'

     Disable binary logging. This is useful for avoiding an endless
     loop if you use the `--to-last-log' option and are sending the
     output to the same MySQL server. This option also is useful when
     restoring after a crash to avoid duplication of the statements you
     have logged.

     This option requires that you have the `SUPER' privilege. It causes
     *Note `mysqlbinlog': mysqlbinlog. to include a `SET sql_log_bin =
     0' statement in its output to disable binary logging of the
     remaining output. The *Note `SET': set-option.  statement is
     ineffective unless you have the `SUPER' privilege.

   *  `--force-read', `-f'

     With this option, if *Note `mysqlbinlog': mysqlbinlog. reads a
     binary log event that it does not recognize, it prints a warning,
     ignores the event, and continues. Without this option, *Note
     `mysqlbinlog': mysqlbinlog. stops if it reads such an event.

   *  `--hexdump', `-H'

     Display a hex dump of the log in comments, as described in *Note
     mysqlbinlog-hexdump::. This output can be helpful for replication
     debugging.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Get the binary log from the MySQL server on the given host.

   *  `--local-load=PATH', `-l PATH'

     Prepare local temporary files for *Note `LOAD DATA INFILE':
     load-data. in the specified directory.

   *  `--offset=N', `-o N'

     Skip the first N entries in the log.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for connecting to a remote server.

   *  `--position=N', `-j N'

     Deprecated. Use `--start-position' instead.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--read-from-remote-server', `-R'

     Read the binary log from a MySQL server rather than reading a
     local log file. Any connection parameter options are ignored
     unless this option is given as well. These options are `--host',
     `--password', `--port', `--protocol', `--socket', and `--user'.

     This option requires that the remote server be running. It works
     only for binary log files on the remote server, not relay log
     files.

   *  `--result-file=NAME', `-r NAME'

     Direct output to the given file.

   *  `--server-id=ID'

     Extract only those events created by the server having the given
     server ID.

   *  `--set-charset=CHARSET_NAME'

     Add a `SET NAMES CHARSET_NAME' statement to the output to specify
     the character set to be used for processing log files.

   *  `--short-form', `-s'

     Display only the statements contained in the log, without any
     extra information.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--start-datetime=DATETIME'

     Start reading the binary log at the first event having a timestamp
     equal to or later than the DATETIME argument. The DATETIME value
     is relative to the local time zone on the machine where you run
     *Note `mysqlbinlog': mysqlbinlog. The value should be in a format
     accepted for the *Note `DATETIME': datetime. or *Note `TIMESTAMP':
     datetime. data types. For example:

          shell> mysqlbinlog --start-datetime="2005-12-25 11:25:56" binlog.000003

     This option is useful for point-in-time recovery. See *Note
     backup-strategy-example::.

   *  `--start-position=N'

     Start reading the binary log at the first event having a position
     equal to or greater than N. This option applies to the first log
     file named on the command line.

   *  `--stop-datetime=DATETIME'

     Stop reading the binary log at the first event having a timestamp
     equal to or later than the DATETIME argument. This option is
     useful for point-in-time recovery. See the description of the
     `--start-datetime' option for information about the DATETIME value.

   *  `--stop-position=N'

     Stop reading the binary log at the first event having a position
     equal to or greater than N. This option applies to the last log
     file named on the command line.

   *  `--to-last-log', `-t'

     Do not stop at the end of the requested binary log from a MySQL
     server, but rather continue printing until the end of the last
     binary log. If you send the output to the same MySQL server, this
     may lead to an endless loop. This option requires
     `--read-from-remote-server'.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL user name to use when connecting to a remote server.

   *  `--verbose', `-v'

     Reconstruct row events and display them as commented SQL
     statements. If given twice, the output includes comments to
     indicate column data types and some metadata. This option was
     added in MySQL 6.0.7.

     For examples that show the effect of `--base64-output' and
     `--verbose' on row event output, see *Note
     mysqlbinlog-row-events::.

   *  `--version', `-V'

     Display version information and exit.

   *  `--write-binlog'

     This option is enabled by default, so that *Note `ANALYZE TABLE':
     analyze-table, *Note `OPTIMIZE TABLE': optimize-table, and *Note
     `REPAIR TABLE': repair-table. statements generated by *Note
     `mysqlcheck': mysqlcheck. are written to the binary log. Use
     `--skip-write-binlog' to cause `NO_WRITE_TO_BINLOG' to be added to
     the statements so that they are not logged. Use the
     `--skip-write-binlog' when these statements should not be sent to
     replication slaves or run when using the binary logs for recovery
     from backup.

You can also set the following variable by using `--VAR_NAME=VALUE'
syntax:

   *  `open_files_limit'

     Specify the number of open file descriptors to reserve.

You can pipe the output of *Note `mysqlbinlog': mysqlbinlog. into the
*Note `mysql': mysql. client to execute the statements contained in the
binary log. This is used to recover from a crash when you have an old
backup (see *Note backup::). For example:

     shell> mysqlbinlog binlog.000001 | mysql

Or:

     shell> mysqlbinlog binlog.[0-9]* | mysql

You can also redirect the output of *Note `mysqlbinlog': mysqlbinlog.
to a text file instead, if you need to modify the statement log first
(for example, to remove statements that you do not want to execute for
some reason).  After editing the file, execute the statements that it
contains by using it as input to the *Note `mysql': mysql. program.

*Note `mysqlbinlog': mysqlbinlog. has the `--start-position' option,
which prints only those statements with an offset in the binary log
greater than or equal to a given position (the given position must
match the start of one event). It also has options to stop and start
when it sees an event with a given date and time. This enables you to
perform point-in-time recovery using the `--stop-datetime' option (to
be able to say, for example, `roll forward my databases to how they
were today at 10:30 a.m.').

If you have more than one binary log to execute on the MySQL server,
the safe method is to process them all using a single connection to the
server. Here is an example that demonstrates what may be _unsafe_:

     shell> mysqlbinlog binlog.000001 | mysql # DANGER!!
     shell> mysqlbinlog binlog.000002 | mysql # DANGER!!

Processing binary logs this way using different connections to the
server causes problems if the first log file contains a *Note `CREATE
TEMPORARY TABLE': create-table. statement and the second log contains a
statement that uses the temporary table. When the first *Note `mysql':
mysql. process terminates, the server drops the temporary table. When
the second *Note `mysql': mysql.  process attempts to use the table,
the server reports `unknown table.'

To avoid problems like this, use a _single_ connection to execute the
contents of all binary logs that you want to process. Here is one way
to do so:

     shell> mysqlbinlog binlog.000001 binlog.000002 | mysql

Another approach is to write all the logs to a single file and then
process the file:

     shell> mysqlbinlog binlog.000001 >  /tmp/statements.sql
     shell> mysqlbinlog binlog.000002 >> /tmp/statements.sql
     shell> mysql -e "source /tmp/statements.sql"

*Note `mysqlbinlog': mysqlbinlog. can produce output that reproduces a
*Note `LOAD DATA INFILE': load-data. operation without the original
data file.  *Note `mysqlbinlog': mysqlbinlog. copies the data to a
temporary file and writes a *Note `LOAD DATA LOCAL INFILE': load-data.
statement that refers to the file. The default location of the
directory where these files are written is system-specific. To specify
a directory explicitly, use the `--local-load' option.

Because *Note `mysqlbinlog': mysqlbinlog. converts *Note `LOAD DATA
INFILE': load-data. statements to *Note `LOAD DATA LOCAL INFILE':
load-data. statements (that is, it adds `LOCAL'), both the client and
the server that you use to process the statements must be configured to
allow `LOCAL' capability. See *Note load-data-local::.

MySQL Enterprise

For expert advice on the security implications of enabling `LOCAL',
subscribe to the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Warning*:

The temporary files created for *Note `LOAD DATA LOCAL': load-data.
statements are _not_ automatically deleted because they are needed
until you actually execute those statements. You should delete the
temporary files yourself after you no longer need the statement log.
The files can be found in the temporary file directory and have names
like ORIGINAL_FILE_NAME-#-#.


File: manual.info,  Node: mysqlbinlog-hexdump,  Next: mysqlbinlog-row-events,  Prev: mysqlbinlog,  Up: mysqlbinlog

4.6.8.1 `mysqlbinlog' Hex Dump Format
.....................................

The `--hexdump' option produces a hex dump of the log contents:

     shell> mysqlbinlog --hexdump master-bin.000001

The hex output consists of comment lines beginning with `#', so the
output might look like this for the preceding command:

     /*!40019 SET @@session.max_insert_delayed_threads=0*/;
     /*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
     # at 4
     #051024 17:24:13 server id 1  end_log_pos 98
     # Position  Timestamp   Type   Master ID        Size      Master Pos    Flags
     # 00000004 9d fc 5c 43   0f   01 00 00 00   5e 00 00 00   62 00 00 00   00 00
     # 00000017 04 00 35 2e 30 2e 31 35  2d 64 65 62 75 67 2d 6c |..5.0.15.debug.l|
     # 00000027 6f 67 00 00 00 00 00 00  00 00 00 00 00 00 00 00 |og..............|
     # 00000037 00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00 |................|
     # 00000047 00 00 00 00 9d fc 5c 43  13 38 0d 00 08 00 12 00 |.......C.8......|
     # 00000057 04 04 04 04 12 00 00 4b  00 04 1a                |.......K...|
     #       Start: binlog v 4, server v 5.0.15-debug-log created 051024 17:24:13
     #       at startup
     ROLLBACK;

Hex dump output currently contains the following elements. This format
is subject to change.

   * `Position': The byte position within the log file.

   * `Timestamp': The event timestamp. In the example shown, `'9d fc 5c
     43'' is the representation of `'051024 17:24:13'' in hexadecimal.

   * `Type': The event type code. In the example shown, `'0f''
     indicates a `FORMAT_DESCRIPTION_EVENT'. The following table lists
     the possible type codes.

     Type                               Name          Meaning
     `00'                               `UNKNOWN_EVENT'This event should never be present in the log.
     `01'                               `START_EVENT_V3'This indicates the start of a log file written by
                                                      MySQL 4 or earlier.
     `02'                               `QUERY_EVENT' The most common type of events. These contain
                                                      statements executed on the master.
     `03'                               `STOP_EVENT'  Indicates that master has stopped.
     `04'                               `ROTATE_EVENT'Written when the master switches to a new log
                                                      file.
     `05'                               `INTVAR_EVENT'Used for `AUTO_INCREMENT' values or when the
                                                      `LAST_INSERT_ID()' function is used in the
                                                      statement.
     `06'                               `LOAD_EVENT'  Used for *Note `LOAD DATA INFILE': load-data. in
                                                      MySQL 3.23.
     `07'                               `SLAVE_EVENT' Reserved for future use.
     `08'                               `CREATE_FILE_EVENT'Used for *Note `LOAD DATA INFILE': load-data.
                                                      statements. This indicates the start of execution
                                                      of such a statement. A temporary file is created
                                                      on the slave. Used in MySQL 4 only.
     `09'                               `APPEND_BLOCK_EVENT'Contains data for use in a *Note `LOAD DATA
                                                      INFILE': load-data. statement. The data is stored
                                                      in the temporary file on the slave.
     `0a'                               `EXEC_LOAD_EVENT'Used for *Note `LOAD DATA INFILE': load-data.
                                                      statements. The contents of the temporary file is
                                                      stored in the table on the slave.  Used in MySQL
                                                      4 only.
     `0b'                               `DELETE_FILE_EVENT'Rollback of a *Note `LOAD DATA INFILE':
                                                      load-data. statement. The temporary file should
                                                      be deleted on the slave.
     `0c'                               `NEW_LOAD_EVENT'Used for *Note `LOAD DATA INFILE': load-data. in
                                                      MySQL 4 and earlier.
     `0d'                               `RAND_EVENT'  Used to send information about random values if
                                                      the `RAND()' function is used in the statement.
     `0e'                               `USER_VAR_EVENT'Used to replicate user variables.
     `0f'                               `FORMAT_DESCRIPTION_EVENT'This indicates the start of a log file written by
                                                      MySQL 5 or later.
     `10'                               `XID_EVENT'   Event indicating commit of an XA transaction.
     `11'                               `BEGIN_LOAD_QUERY_EVENT'Used for *Note `LOAD DATA INFILE': load-data.
                                                      statements in MySQL 5 and later.
     `12'                               `EXECUTE_LOAD_QUERY_EVENT'Used for *Note `LOAD DATA INFILE': load-data.
                                                      statements in MySQL 5 and later.
     `13'                               `TABLE_MAP_EVENT'Information about a table definition. Used in
                                                      MySQL 5.1.5 and later.
     `14'                               `PRE_GA_WRITE_ROWS_EVENT'Row data for a single table that should be
                                                      created. Used in MySQL 5.1.5 to 5.1.17.
     `15'                               `PRE_GA_UPDATE_ROWS_EVENT'Row data for a single table that needs to be
                                                      updated. Used in MySQL 5.1.5 to 5.1.17.
     `16'                               `PRE_GA_DELETE_ROWS_EVENT'Row data for a single table that should be
                                                      deleted. Used in MySQL 5.1.5 to 5.1.17.
     `17'                               `WRITE_ROWS_EVENT'Row data for a single table that should be
                                                      created. Used in MySQL 5.1.18 and later.
     `18'                               `UPDATE_ROWS_EVENT'Row data for a single table that needs to be
                                                      updated. Used in MySQL 5.1.18 and later.
     `19'                               `DELETE_ROWS_EVENT'Row data for a single table that should be
                                                      deleted. Used in MySQL 5.1.18 and later.
     `1a'                               `INCIDENT_EVENT'Something out of the ordinary happened. Added in
                                                      MySQL 5.1.18.
     `1b'                               `HEARTBEAT_LOG_EVENT'Heartbeat sent by master to slave. Added in MySQL
                                                      6.0.5.

   * `Master ID': The server ID of the master that created the event.

   * `Size': The size in bytes of the event.

   * `Master Pos': The position of the next event in the original
     master log file.

   * `Flags': 16 flags. Currently, the following flags are used. The
     others are reserved for future use.

     Flag                               Name          Meaning
     `01'                               `LOG_EVENT_BINLOG_IN_USE_F'Log file correctly closed. (Used only in
                                                      `FORMAT_DESCRIPTION_EVENT'.) If this flag is set
                                                      (if the flags are, for example, `'01 00'') in a
                                                      `FORMAT_DESCRIPTION_EVENT', the log file has not
                                                      been properly closed. Most probably this is
                                                      because of a master crash (for example, due to
                                                      power failure).
     `02'                                             Reserved for future use.
     `04'                               `LOG_EVENT_THREAD_SPECIFIC_F'Set if the event is dependent on the connection
                                                      it was executed in (for example, `'04 00''), for
                                                      example, if the event uses temporary tables.
     `08'                               `LOG_EVENT_SUPPRESS_USE_F'Set in some circumstances when the event is not
                                                      dependent on the default database.


File: manual.info,  Node: mysqlbinlog-row-events,  Prev: mysqlbinlog-hexdump,  Up: mysqlbinlog

4.6.8.2 `mysqlbinlog' Row Event Display
.......................................

The following examples illustrate how *Note `mysqlbinlog': mysqlbinlog.
displays row events that specify data modifications. These correspond
to events with the `WRITE_ROWS_EVENT', `UPDATE_ROWS_EVENT', and
`DELETE_ROWS_EVENT' type codes. The `--base64-output=DECODE-ROWS' and
`--verbose' options may be used to affect row event output. These
options are available as of MySQL 6.0.7.

Suppose that the server is using row-based binary logging and that you
execute the following sequence of statements:

     CREATE TABLE t
     (
       id   INT NOT NULL,
       name VARCHAR(20) NOT NULL,
       date DATE NULL
     ) ENGINE = InnoDB;

     START TRANSACTION;
     INSERT INTO t VALUES(1, 'apple', NULL);
     UPDATE t SET name = 'pear', date = '2009-01-01' WHERE id = 1;
     DELETE FROM t WHERE id = 1;
     COMMIT;

By default, *Note `mysqlbinlog': mysqlbinlog. displays row events
encoded as base-64 strings using *Note `BINLOG': binlog. statements.
Omitting extraneous lines, the output for the row events produced by the
preceding statement sequence looks like this:

     shell> mysqlbinlog LOG_FILE
     ...
     # at 218
     #080828 15:03:08 server id 1  end_log_pos 258 	Write_rows: table id 17 flags: STMT_END_F

     BINLOG '
     fAS3SBMBAAAALAAAANoAAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
     fAS3SBcBAAAAKAAAAAIBAAAQABEAAAAAAAEAA//8AQAAAAVhcHBsZQ==
     '/*!*/;
     ...
     # at 302
     #080828 15:03:08 server id 1  end_log_pos 356 	Update_rows: table id 17 flags: STMT_END_F

     BINLOG '
     fAS3SBMBAAAALAAAAC4BAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
     fAS3SBgBAAAANgAAAGQBAAAQABEAAAAAAAEAA////AEAAAAFYXBwbGX4AQAAAARwZWFyIbIP
     '/*!*/;
     ...
     # at 400
     #080828 15:03:08 server id 1  end_log_pos 442 	Delete_rows: table id 17 flags: STMT_END_F

     BINLOG '
     fAS3SBMBAAAALAAAAJABAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
     fAS3SBkBAAAAKgAAALoBAAAQABEAAAAAAAEAA//4AQAAAARwZWFyIbIP
     '/*!*/;

To see the row events as comments in the form of `pseudo-SQL'
statements, run *Note `mysqlbinlog': mysqlbinlog. with the `--verbose'
or `-v' option. The output will contain lines beginning with `###':

     shell> mysqlbinlog -v LOG_FILE
     ...
     # at 218
     #080828 15:03:08 server id 1  end_log_pos 258 	Write_rows: table id 17 flags: STMT_END_F

     BINLOG '
     fAS3SBMBAAAALAAAANoAAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
     fAS3SBcBAAAAKAAAAAIBAAAQABEAAAAAAAEAA//8AQAAAAVhcHBsZQ==
     '/*!*/;
     ### INSERT INTO test.t
     ### SET
     ###   @1=1
     ###   @2='apple'
     ###   @3=NULL
     ...
     # at 302
     #080828 15:03:08 server id 1  end_log_pos 356 	Update_rows: table id 17 flags: STMT_END_F

     BINLOG '
     fAS3SBMBAAAALAAAAC4BAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
     fAS3SBgBAAAANgAAAGQBAAAQABEAAAAAAAEAA////AEAAAAFYXBwbGX4AQAAAARwZWFyIbIP
     '/*!*/;
     ### UPDATE test.t
     ### WHERE
     ###   @1=1
     ###   @2='apple'
     ###   @3=NULL
     ### SET
     ###   @1=1
     ###   @2='pear'
     ###   @3='2009:01:01'
     ...
     # at 400
     #080828 15:03:08 server id 1  end_log_pos 442 	Delete_rows: table id 17 flags: STMT_END_F

     BINLOG '
     fAS3SBMBAAAALAAAAJABAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
     fAS3SBkBAAAAKgAAALoBAAAQABEAAAAAAAEAA//4AQAAAARwZWFyIbIP
     '/*!*/;
     ### DELETE FROM test.t
     ### WHERE
     ###   @1=1
     ###   @2='pear'
     ###   @3='2009:01:01'

Specify `--verbose' or `-v' twice to also display data types and some
metadata for each column. The output will contain an additional comment
following each column change:

     shell> mysqlbinlog -vv LOG_FILE
     ...
     # at 218
     #080828 15:03:08 server id 1  end_log_pos 258 	Write_rows: table id 17 flags: STMT_END_F

     BINLOG '
     fAS3SBMBAAAALAAAANoAAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
     fAS3SBcBAAAAKAAAAAIBAAAQABEAAAAAAAEAA//8AQAAAAVhcHBsZQ==
     '/*!*/;
     ### INSERT INTO test.t
     ### SET
     ###   @1=1 /* INT meta=0 nullable=0 is_null=0 */
     ###   @2='apple' /* VARSTRING(20) meta=20 nullable=0 is_null=0 */
     ###   @3=NULL /* VARSTRING(20) meta=0 nullable=1 is_null=1 */
     ...
     # at 302
     #080828 15:03:08 server id 1  end_log_pos 356 	Update_rows: table id 17 flags: STMT_END_F

     BINLOG '
     fAS3SBMBAAAALAAAAC4BAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
     fAS3SBgBAAAANgAAAGQBAAAQABEAAAAAAAEAA////AEAAAAFYXBwbGX4AQAAAARwZWFyIbIP
     '/*!*/;
     ### UPDATE test.t
     ### WHERE
     ###   @1=1 /* INT meta=0 nullable=0 is_null=0 */
     ###   @2='apple' /* VARSTRING(20) meta=20 nullable=0 is_null=0 */
     ###   @3=NULL /* VARSTRING(20) meta=0 nullable=1 is_null=1 */
     ### SET
     ###   @1=1 /* INT meta=0 nullable=0 is_null=0 */
     ###   @2='pear' /* VARSTRING(20) meta=20 nullable=0 is_null=0 */
     ###   @3='2009:01:01' /* DATE meta=0 nullable=1 is_null=0 */
     ...
     # at 400
     #080828 15:03:08 server id 1  end_log_pos 442 	Delete_rows: table id 17 flags: STMT_END_F

     BINLOG '
     fAS3SBMBAAAALAAAAJABAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
     fAS3SBkBAAAAKgAAALoBAAAQABEAAAAAAAEAA//4AQAAAARwZWFyIbIP
     '/*!*/;
     ### DELETE FROM test.t
     ### WHERE
     ###   @1=1 /* INT meta=0 nullable=0 is_null=0 */
     ###   @2='pear' /* VARSTRING(20) meta=20 nullable=0 is_null=0 */
     ###   @3='2009:01:01' /* DATE meta=0 nullable=1 is_null=0 */

You can tell *Note `mysqlbinlog': mysqlbinlog. to suppress the *Note
`BINLOG': binlog. statements for row events by using the
`--base64-output=DECODE-ROWS' option. This is similar to
`--base64-output=NEVER' but does not exit with an error if a row event
is found. The combination of `--base64-output=DECODE-ROWS' and
`--verbose' provides a convenient way to see row events only as SQL
statements:

     shell> mysqlbinlog -v --base64-output=DECODE-ROWS LOG_FILE
     ...
     # at 218
     #080828 15:03:08 server id 1  end_log_pos 258 	Write_rows: table id 17 flags: STMT_END_F
     ### INSERT INTO test.t
     ### SET
     ###   @1=1
     ###   @2='apple'
     ###   @3=NULL
     ...
     # at 302
     #080828 15:03:08 server id 1  end_log_pos 356 	Update_rows: table id 17 flags: STMT_END_F
     ### UPDATE test.t
     ### WHERE
     ###   @1=1
     ###   @2='apple'
     ###   @3=NULL
     ### SET
     ###   @1=1
     ###   @2='pear'
     ###   @3='2009:01:01'
     ...
     # at 400
     #080828 15:03:08 server id 1  end_log_pos 442 	Delete_rows: table id 17 flags: STMT_END_F
     ### DELETE FROM test.t
     ### WHERE
     ###   @1=1
     ###   @2='pear'
     ###   @3='2009:01:01'

*Note*:

You should not suppress *Note `BINLOG': binlog.  statements if you
intend to re-execute *Note `mysqlbinlog': mysqlbinlog. output.

The SQL statements produced by `--verbose' for row events are much more
readable than the corresponding *Note `BINLOG': binlog. statements.
However, they do not correspond exactly to the original SQL statements
that generated the events. The following limitations apply:

   * The original column names are lost and replace by `@N', where N is
     a column number.

   * Character set information is not available in the binary log,
     which affects string column display:

        * There is no distinction made between corresponding binary and
          non-binary string types (*Note `BINARY': binary-varbinary. and
          *Note `CHAR': char, *Note `VARBINARY': binary-varbinary. and
          *Note `VARCHAR': char, *Note `BLOB': blob. and *Note `TEXT':
          blob.). The output uses a data type of `STRING' for
          fixed-length strings and `VARSTRING' for variable-length
          strings.

        * For multi-byte character sets, the maximum number of bytes
          per character is not present in the binary log, so the length
          for string types is displayed in bytes rather than in
          characters. For example, `STRING(4)' will be used as the data
          type for values from either of these column types:

               CHAR(4) CHARACTER SET latin1
               CHAR(2) CHARACTER SET ucs2

        * Due to the storage format for events of type
          `UPDATE_ROWS_EVENT', *Note `UPDATE': update. statements are
          displayed with the `WHERE' clause preceding the `SET' clause.


File: manual.info,  Node: mysqldumpslow,  Next: mysqlhotcopy,  Prev: mysqlbinlog,  Up: programs-admin-utils

4.6.9 `mysqldumpslow' -- Summarize Slow Query Log Files
-------------------------------------------------------

The MySQL slow query log contains information about queries that take a
long time to execute (see *Note slow-query-log::).  *Note
`mysqldumpslow': mysqldumpslow. parses MySQL slow query log files and
prints a summary of their contents.

Normally, *Note `mysqldumpslow': mysqldumpslow. groups queries that are
similar except for the particular values of number and string data
values. It `abstracts' these values to `N' and `'S'' when displaying
summary output. The `-a' and `-n' options can be used to modify value
abstracting behavior.

Invoke *Note `mysqldumpslow': mysqldumpslow. like this:

     shell> mysqldumpslow [OPTIONS] [LOG_FILE ...]

*`mysqldumpslow' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-a                      Do not abstract all numbers to N             
                        and strings to S                             
-debug      debug       Write debugging information                  
-g pattern              Only consider statements that match          
                        the pattern                                  
-help                   Display help message and exit                
-h name                 Host name of the server in the log           
                        file name                                    
-i name                 Name of the server instance                  
-l                      Do not subtract lock time from               
                        total time                                   
-n num                  Abstract numbers with at least the           
                        specified digits                             
-r                      Reverse the sort order                       
-s value                How to sort output                           
-t num                  Display only first num queries               
-verbose    verbose     Verbose mode                                 

*Note `mysqldumpslow': mysqldumpslow. supports the following options:

   *  `--help'

     Display a help message and exit.

   *  `-a'

     Do not abstract all numbers to `N' and strings to `'S''.

   *  `--debug', `-d'

     Run in debug mode.

   *  `-g PATTERN'

     Consider only queries that match the (`grep'-style) pattern.

   *  `-h HOST_NAME'

     Host name of MySQL server for `*-slow.log' file name. The value can
     contain a wildcare. The default is `*' (match all).

   *  `-i NAME'

     Name of server instance (if using *Note `mysql.server':
     mysql-server. startup script).

   *  `-l'

     Do not subtract lock time from total time.

   *  `-n N'

     Abstract numbers with at least N digits within names.

   *  `-r'

     Reverse the sort order.

   *  `-s SORT_TYPE'

     How to sort the output. The value of SORT_TYPE should be chosen
     from the following list:

        * `t', `at': Sort by query time or average query time

        * `l', `al': Sort by lock time or average lock time

        * `s', `as': Sort by rows sent or average rows went

        * `c': Sort by count

   *  `-t N'

     Display only the first N queries in the output.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.

Example of usage:

     shell> mysqldumpslow

     Reading mysql slow query log from /usr/local/mysql/data/mysqld51-apple-slow.log
     Count: 1  Time=4.32s (4s)  Lock=0.00s (0s)  Rows=0.0 (0), root[root]@localhost
      insert into t2 select * from t1

     Count: 3  Time=2.53s (7s)  Lock=0.00s (0s)  Rows=0.0 (0), root[root]@localhost
      insert into t2 select * from t1 limit N

     Count: 3  Time=2.13s (6s)  Lock=0.00s (0s)  Rows=0.0 (0), root[root]@localhost
      insert into t1 select * from t1


File: manual.info,  Node: mysqlhotcopy,  Next: mysql-convert-table-format,  Prev: mysqldumpslow,  Up: programs-admin-utils

4.6.10 `mysqlhotcopy' -- A Database Backup Program
--------------------------------------------------

*Note `mysqlhotcopy': mysqlhotcopy. is a Perl script that was
originally written and contributed by Tim Bunce. It uses *Note `LOCK
TABLES': lock-tables, *Note `FLUSH TABLES': flush, and `cp' or `scp' to
make a database backup quickly. It is the fastest way to make a backup
of the database or single tables, but it can be run only on the same
machine where the database directories are located.  *Note
`mysqlhotcopy': mysqlhotcopy. works only for backing up `MyISAM' and
`ARCHIVE' tables.  It runs on Unix and NetWare.

     shell> mysqlhotcopy DB_NAME [/PATH/TO/NEW_DIRECTORY]

     shell> mysqlhotcopy DB_NAME_1 ... DB_NAME_N /PATH/TO/NEW_DIRECTORY

Back up tables in the given database that match a regular expression:

     shell> mysqlhotcopy DB_NAME./REGEX/

The regular expression for the table name can be negated by prefixing
it with a tilde (``~''):

     shell> mysqlhotcopy DB_NAME./~REGEX/

*`mysqlhotcopy' Option Reference*

Format      Config File Description                          IntroductionDeprecated
-addtodest  addtodest   Do not rename target directory (if           
                        it exists); merely add files to  it          
-allowold   allowold    Do not abort if a target exists;             
                        rename it by adding an _old  suffix          
-checkpoint=db_name.tbl_namecheckpoint  Insert checkpoint entries                    
-chroot=pathchroot      Base directory of the chroot jail            
                        in which mysqld operates                     
-debug      debug       Write a debugging log                        
-dryrun     dryrun      Report actions without performing            
                        them                                         
-flushlogs  flushlogs   Flush logs after all tables are              
                        locked                                       
-help                   Display help message and exit                
-host=host_namehost        Connect to the MySQL server on the           
                        given host                                   
-keepold    keepold     Do not delete previous (renamed)             
                        target when done                             
-noindices  noindices   Do not include full index files in           
                        the backup                                   
-password[=password]password    The password to use when connecting          
                        to the server                                
-port=port_numport        The TCP/IP port number to use for            
                        the connection                               
-quiet      quiet       Be silent except for errors                  
-regexp     regexp      Copy all databases with names that           
                        match the given regular  expression          
-resetmasterresetmaster Reset the binary log after locking           
                        all the tables                               
-resetslave resetslave  Reset the master.info file after             
                        locking all the tables                       
-socket=pathsocket      For connections to localhost                 
-tmpdir=pathtmpdir      The temporary directory                      
-user=user_name,user        The MySQL user name to use when              
                        connecting to the server                     
-version                Display version information and exit         

*Note `mysqlhotcopy': mysqlhotcopy. supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--addtodest'

     Do not rename target directory (if it exists); merely add files to
     it.

   *  `--allowold'

     Do not abort if a target exists; rename it by adding an `_old'
     suffix.

   *  `--checkpoint=DB_NAME.TBL_NAME'

     Insert checkpoint entries into the specified database DB_NAME and
     table TBL_NAME.

   *  `--chroot=PATH'

     Base directory of the `chroot' jail in which *Note `mysqld':
     mysqld. operates. The PATH value should match that of the
     `--chroot' option given to *Note `mysqld': mysqld.

   *  `--debug'

     Enable debug output.

   *  `--dryrun', `-n'

     Report actions without performing them.

   *  `--flushlog'

     Flush logs after all tables are locked.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     The host name of the local host to use for making a TCP/IP
     connection to the local server. By default, the connection is made
     to `localhost' using a Unix socket file.

   *  `--keepold'

     Do not delete previous (renamed) target when done.

   *  `--method=COMMAND'

     The method for copying files (`cp' or `scp').

   *  `--noindices'

     Do not include full index files in the backup. This makes the
     backup smaller and faster. The indexes for reloaded tables can be
     reconstructed later with *Note `myisamchk -rq': myisamchk.

   *  `--password=PASSWORD', `-pPASSWORD'

     The password to use when connecting to the server. Note that the
     password value is not optional for this option, unlike for other
     MySQL programs. You can use an option file to avoid giving the
     password on the command line.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use when connecting to the local server.

   *  `--quiet', `-q'

     Be silent except for errors.

   *  `--record_log_pos=DB_NAME.TBL_NAME'

     Record master and slave status in the specified database DB_NAME
     and table TBL_NAME.

   *  `--regexp=EXPR'

     Copy all databases with names that match the given regular
     expression.

   *  `--resetmaster'

     Reset the binary log after locking all the tables.

   *  `--resetslave'

     Reset the `master.info' file after locking all the tables.

   *  `--socket=PATH', `-S PATH'

     The Unix socket file to use for the connection.

   *  `--suffix=STR'

     The suffix for names of copied databases.

   *  `--tmpdir=PATH'

     The temporary directory. The default is `/tmp'.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL user name to use when connecting to the server.

*Note `mysqlhotcopy': mysqlhotcopy. reads the `[client]' and
`[mysqlhotcopy]' option groups from option files.

To execute *Note `mysqlhotcopy': mysqlhotcopy, you must have access to
the files for the tables that you are backing up, the `SELECT'
privilege for those tables, the `RELOAD' privilege (to be able to
execute *Note `FLUSH TABLES': flush.), and the `LOCK TABLES' privilege
(to be able to lock the tables).

Use `perldoc' for additional *Note `mysqlhotcopy': mysqlhotcopy.
documentation, including information about the structure of the tables
needed for the `--checkpoint' and `--record_log_pos' options:

     shell> perldoc mysqlhotcopy

MySQL Enterprise

MySQL Enterprise subscribers will find more information about *Note
`mysqlhotcopy': mysqlhotcopy. in the Knowledge Base article, How Does
mysqlhotcopy Work? (https://kb.mysql.com/view.php?id=5919). Access to
the MySQL Knowledge Base collection of articles is one of the
advantages of subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: mysql-convert-table-format,  Next: mysql-find-rows,  Prev: mysqlhotcopy,  Up: programs-admin-utils

4.6.11 `mysql_convert_table_format' -- Convert Tables to Use a Given Storage Engine
-----------------------------------------------------------------------------------

*Note `mysql_convert_table_format': mysql-convert-table-format.
converts the tables in a database to use a particular storage engine
(`MyISAM' by default).  *Note `mysql_convert_table_format':
mysql-convert-table-format. is written in Perl and requires that the
`DBI' and `DBD::mysql' Perl modules be installed (see *Note
perl-support::).

Invoke *Note `mysql_convert_table_format': mysql-convert-table-format.
like this:

     shell> mysql_convert_table_format [OPTIONS]DB_NAME

The DB_NAME argument indicates the database containing the tables to be
converted.

*Note `mysql_convert_table_format': mysql-convert-table-format.
supports the options described in the following list.

   *  `--help'

     Display a help message and exit.

   *  `--force'

     Continue even if errors occur.

   *  `--host=HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--password=PASSWORD'

     The password to use when connecting to the server. Note that the
     password value is not optional for this option, unlike for other
     MySQL programs. You can use an option file to avoid giving the
     password on the command line.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--port=PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--socket=PATH'

     For connections to `localhost', the Unix socket file to use.

   *  `--type=ENGINE_NAME'

     Specify the storage engine that the tables should be converted to
     use. The default is `MyISAM' if this option is not given.

     MySQL Enterprise

     For expert advice on choosing the optimum storage engine,
     subscribe to the MySQL Enterprise Monitor. For more information,
     see `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--user=USER_NAME'

     The MySQL user name to use when connecting to the server.

   *  `--verbose'

     Verbose mode. Print more information about what the program does.

   *  `--version'

     Display version information and exit.


File: manual.info,  Node: mysql-find-rows,  Next: mysql-fix-extensions,  Prev: mysql-convert-table-format,  Up: programs-admin-utils

4.6.12 `mysql_find_rows' -- Extract SQL Statements from Files
-------------------------------------------------------------

*Note `mysql_find_rows': mysql-find-rows. reads files containing SQL
statements and extracts statements that match a given regular
expression or that contain `USE DB_NAME' or *Note `SET': set-option.
statements. The utility was written for use with update log files (as
used prior to MySQL 5.0) and as such expects statements to be
terminated with semicolon (`;') characters. It may be useful with other
files that contain SQL statements as long as statements are terminated
with semicolons.

Invoke *Note `mysql_find_rows': mysql-find-rows. like this:

     shell> mysql_find_rows [OPTIONS] [FILE_NAME ...]

Each FILE_NAME argument should be the name of file containing SQL
statements. If no file names are given, *Note `mysql_find_rows':
mysql-find-rows. reads the standard input.

Examples:

     mysql_find_rows --regexp=problem_table --rows=20 < update.log
     mysql_find_rows --regexp=problem_table  update-log.1 update-log.2

*Note `mysql_find_rows': mysql-find-rows. supports the following
options:

   *  `--help', `--Information'

     Display a help message and exit.

   *  `--regexp=PATTERN'

     Display queries that match the pattern.

   *  `--rows=N'

     Quit after displaying N queries.

   *  `--skip-use-db'

     Do not include `USE DB_NAME' statements in the output.

   *  `--start_row=N'

     Start output from this row.


File: manual.info,  Node: mysql-fix-extensions,  Next: mysql-setpermission,  Prev: mysql-find-rows,  Up: programs-admin-utils

4.6.13 `mysql_fix_extensions' -- Normalize Table File Name Extensions
---------------------------------------------------------------------

*Note `mysql_fix_extensions': mysql-fix-extensions. converts the
extensions for `MyISAM' (or `ISAM') table files to their canonical
forms. It looks for files with extensions matching any lettercase
variant of `.frm', `.myd', `.myi', `.isd', and `.ism' and renames them
to have extensions of `.frm', `.MYD', `.MYI', `.ISD', and `.ISM',
respectively. This can be useful after transferring the files from a
system with case-insensitive file names (such as Windows) to a system
with case-sensitive file names.

Invoke *Note `mysql_fix_extensions': mysql-fix-extensions. like this,
where DATA_DIR is the path name to the MySQL data directory.

     shell> mysql_fix_extensions DATA_DIR


File: manual.info,  Node: mysql-setpermission,  Next: mysql-waitpid,  Prev: mysql-fix-extensions,  Up: programs-admin-utils

4.6.14 `mysql_setpermission' -- Interactively Set Permissions in Grant Tables
-----------------------------------------------------------------------------

*Note `mysql_setpermission': mysql-setpermission. is a Perl script that
was originally written and contributed by Luuk de Boer. It
interactively sets permissions in the MySQL grant tables.  *Note
`mysql_setpermission': mysql-setpermission. is written in Perl and
requires that the `DBI' and `DBD::mysql' Perl modules be installed (see
*Note perl-support::).

Invoke *Note `mysql_setpermission': mysql-setpermission. like this:

     shell> mysql_setpermission [OPTIONS]

OPTIONS should be either `--help' to display the help message, or
options that indicate how to connect to the MySQL server. The account
used when you connect determines which permissions you have when
attempting to modify existing permissions in the grant tables.

`mysql_setpermissions' also reads options from the `[client]' and
`[perl]' groups in the `.my.cnf' file in your home directory, if the
file exists.

*Note `mysql_setpermission': mysql-setpermission. supports the following
options:

   *  `--help'

     Display a help message and exit.

   *  `--host=HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--password=PASSWORD'

     The password to use when connecting to the server. Note that the
     password value is not optional for this option, unlike for other
     MySQL programs. You can use an option file to avoid giving the
     password on the command line.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security-user::.

   *  `--port=PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--socket=PATH'

     For connections to `localhost', the Unix socket file to use.

   *  `--user=USER_NAME'

     The MySQL user name to use when connecting to the server.


File: manual.info,  Node: mysql-waitpid,  Next: mysql-zap,  Prev: mysql-setpermission,  Up: programs-admin-utils

4.6.15 `mysql_waitpid' -- Kill Process and Wait for Its Termination
-------------------------------------------------------------------

*Note `mysql_waitpid': mysql-waitpid. signals a process to terminate
and waits for the process to exit. It uses the `kill()' system call and
Unix signals, so it runs on Unix and Unix-like systems.

Invoke *Note `mysql_waitpid': mysql-waitpid. like this:

     shell> mysql_waitpid [OPTIONS] PID WAIT_TIME

*Note `mysql_waitpid': mysql-waitpid. sends signal 0 to the process
identified by PID and waits up to WAIT_TIME seconds for the process to
terminate. PID and WAIT_TIME must be positive integers.

If process termination occurs within the wait time or the process does
not exist, *Note `mysql_waitpid': mysql-waitpid. returns 0. Otherwise,
it returns 1.

If the `kill()' system call cannot handle signal 0, `mysql_waitpid()'
uses signal 1 instead.

*Note `mysql_waitpid': mysql-waitpid. supports the following options:

   *  `--help', `-?', `-I'

     Display a help message and exit.

   *  `--verbose', `-v'

     Verbose mode. Display a warning if signal 0 could not be used and
     signal 1 is used instead.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: mysql-zap,  Prev: mysql-waitpid,  Up: programs-admin-utils

4.6.16 `mysql_zap' -- Kill Processes That Match a Pattern
---------------------------------------------------------

*Note `mysql_zap': mysql-zap. kills processes that match a pattern. It
uses the `ps' command and Unix signals, so it runs on Unix and
Unix-like systems.

Invoke *Note `mysql_zap': mysql-zap. like this:

     shell> mysql_zap [-SIGNAL] [-?Ift] PATTERN

A process matches if its output line from the `ps' command contains the
pattern. By default, *Note `mysql_zap': mysql-zap. asks for
confirmation for each process. Respond `y' to kill the process, or `q'
to exit *Note `mysql_zap': mysql-zap. For any other response, *Note
`mysql_zap': mysql-zap. does not attempt to kill the process.

If the `-SIGNAL' option is given, it specifies the name or number of
the signal to send to each process. Otherwise, *Note `mysql_zap':
mysql-zap.  tries first with `TERM' (signal 15) and then with *Note
`KILL': kill. (signal 9).

*Note `mysql_zap': mysql-zap. supports the following additional options:

   *  `--help', `-?', `-I'

     Display a help message and exit.

   *  `-f'

     Force mode. *Note `mysql_zap': mysql-zap. attempts to kill each
     process without confirmation.

   *  `-t'

     Test mode. Display information about each process but do not kill
     it.


File: manual.info,  Node: programs-development,  Next: programs-miscellaneous,  Prev: programs-admin-utils,  Up: programs

4.7 MySQL Program Development Utilities
=======================================

* Menu:

* msql2mysql::                   `msql2mysql' --- Convert mSQL Programs for Use with MySQL
* mysql-config::                 `mysql_config' --- Get Compile Options for Compiling Clients
* my-print-defaults::            `my_print_defaults' --- Display Options from Option Files
* resolve-stack-dump::           `resolve_stack_dump' --- Resolve Numeric Stack Trace Dump to Symbols

This section describes some utilities that you may find useful when
developing MySQL programs.

In shell scripts, you can use the *Note `my_print_defaults':
my-print-defaults. program to parse option files and see what options
would be used by a given program. The following example shows the
output that *Note `my_print_defaults': my-print-defaults.  might
produce when asked to show the options found in the `[client]' and
`[mysql]' groups:

     shell> my_print_defaults client mysql
     --port=3306
     --socket=/tmp/mysql.sock
     --no-auto-rehash

*Note_for developers*: Option file handling is implemented in the C
client library simply by processing all options in the appropriate
group or groups before any command-line arguments. This works well for
programs that use the last instance of an option that is specified
multiple times. If you have a C or C++ program that handles multiply
specified options this way but that doesn't read option files, you need
add only two lines to give it that capability. Check the source code of
any of the standard MySQL clients to see how to do this.

Several other language interfaces to MySQL are based on the C client
library, and some of them provide a way to access option file contents.
These include Perl and Python. For details, see the documentation for
your preferred interface.


File: manual.info,  Node: msql2mysql,  Next: mysql-config,  Prev: programs-development,  Up: programs-development

4.7.1 `msql2mysql' -- Convert mSQL Programs for Use with MySQL
--------------------------------------------------------------

Initially, the MySQL C API was developed to be very similar to that for
the mSQL database system. Because of this, mSQL programs often can be
converted relatively easily for use with MySQL by changing the names of
the C API functions.

The *Note `msql2mysql': msql2mysql. utility performs the conversion of
mSQL C API function calls to their MySQL equivalents. *Note
`msql2mysql': msql2mysql. converts the input file in place, so make a
copy of the original before converting it. For example, use *Note
`msql2mysql': msql2mysql. like this:

     shell> cp client-prog.c client-prog.c.orig
     shell> msql2mysql client-prog.c
     client-prog.c converted

Then examine `client-prog.c' and make any post-conversion revisions
that may be necessary.

*Note `msql2mysql': msql2mysql. uses the *Note `replace':
replace-utility. utility to make the function name substitutions. See
*Note replace-utility::.


File: manual.info,  Node: mysql-config,  Next: my-print-defaults,  Prev: msql2mysql,  Up: programs-development

4.7.2 `mysql_config' -- Get Compile Options for Compiling Clients
-----------------------------------------------------------------

*Note `mysql_config': mysql-config. provides you with useful
information for compiling your MySQL client and connecting it to MySQL.

*Note `mysql_config': mysql-config. supports the following options:

   *  `--cflags'

     Compiler flags to find include files and critical compiler flags
     and defines used when compiling the `libmysqlclient' library. The
     options returned are tied to the specific compiler that was used
     when the library was created and might clash with the settings for
     your own compiler. Use `--include' for more portable options that
     contain only include paths.

   *  `--include'

     Compiler options to find MySQL include files.

   *  `--libmysqld-libs', `--embedded'

     Libraries and options required to link with the MySQL embedded
     server.

   *  `--libs'

     Libraries and options required to link with the MySQL client
     library.

   *  `--libs_r'

     Libraries and options required to link with the thread-safe MySQL
     client library.

   *  `--plugindir'

     The default plugin directory path name, defined when configuring
     MySQL. This option was added in MySQL 6.0.5.

   *  `--port'

     The default TCP/IP port number, defined when configuring MySQL.

   *  `--socket'

     The default Unix socket file, defined when configuring MySQL.

   *  `--version'

     Version number for the MySQL distribution.

If you invoke *Note `mysql_config': mysql-config. with no options, it
displays a list of all options that it supports, and their values:

     shell> mysql_config
     Usage: /usr/local/mysql/bin/mysql_config [options]
     Options:
       --cflags         [-I/usr/local/mysql/include/mysql -mcpu=pentiumpro]
       --include        [-I/usr/local/mysql/include/mysql]
       --libs           [-L/usr/local/mysql/lib/mysql -lmysqlclient -lz
                         -lcrypt -lnsl -lm -L/usr/lib -lssl -lcrypto]
       --libs_r         [-L/usr/local/mysql/lib/mysql -lmysqlclient_r
                         -lpthread -lz -lcrypt -lnsl -lm -lpthread]
       --socket         [/tmp/mysql.sock]
       --port           [3306]
       --version        [4.0.16]
       --libmysqld-libs [-L/usr/local/mysql/lib/mysql -lmysqld -lpthread -lz
                         -lcrypt -lnsl -lm -lpthread -lrt]

You can use *Note `mysql_config': mysql-config. within a command line
to include the value that it displays for a particular option. For
example, to compile a MySQL client program, use *Note `mysql_config':
mysql-config. as follows:

     shell> CFG=/usr/local/mysql/bin/mysql_config
     shell> sh -c "gcc -o progname `$CFG --include` progname.c `$CFG --libs`"

When you use *Note `mysql_config': mysql-config. this way, be sure to
invoke it within backtick (```'') characters. That tells the shell to
execute it and substitute its output into the surrounding command.


File: manual.info,  Node: my-print-defaults,  Next: resolve-stack-dump,  Prev: mysql-config,  Up: programs-development

4.7.3 `my_print_defaults' -- Display Options from Option Files
--------------------------------------------------------------

*Note `my_print_defaults': my-print-defaults. displays the options that
are present in option groups of option files. The output indicates what
options will be used by programs that read the specified option groups.
For example, the *Note `mysqlcheck': mysqlcheck. program reads the
`[mysqlcheck]' and `[client]' option groups. To see what options are
present in those groups in the standard option files, invoke *Note
`my_print_defaults': my-print-defaults. like this:

     shell> my_print_defaults mysqlcheck client
     --user=myusername
     --password=secret
     --host=localhost

The output consists of options, one per line, in the form that they
would be specified on the command line.

*Note `my_print_defaults': my-print-defaults. supports the following
options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--config-file=FILE_NAME',

     `--defaults-file=FILE_NAME', `-c FILE_NAME'

     Read only the given option file.

   *  `--debug=DEBUG_OPTIONS, -# DEBUG_OPTIONS'

     Write a debugging log. A typical DEBUG_OPTIONS string is
     `'d:t:o,FILE_NAME''.  The default is
     `'d:t:o,/tmp/my_print_defaults.trace''.

   *  `--defaults-extra-file=FILE_NAME',

     `--extra-file=FILE_NAME', `-e FILE_NAME'

     Read this option file after the global option file but (on Unix)
     before the user option file.

   *  `--defaults-group-suffix=SUFFIX', `-g SUFFIX'

     In addition to the groups named on the command line, read groups
     that have the given suffix.

   *  `--no-defaults', `-n'

     Return an empty string.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: resolve-stack-dump,  Prev: my-print-defaults,  Up: programs-development

4.7.4 `resolve_stack_dump' -- Resolve Numeric Stack Trace Dump to Symbols
-------------------------------------------------------------------------

*Note `resolve_stack_dump': resolve-stack-dump. resolves a numeric stack
dump to symbols.

Invoke *Note `resolve_stack_dump': resolve-stack-dump. like this:

     shell> resolve_stack_dump [OPTIONS] SYMBOLS_FILE [NUMERIC_DUMP_FILE]

The symbols file should include the output from the `nm --numeric-sort
mysqld' command. The numeric dump file should contain a numeric stack
track from *Note `mysqld': mysqld. If no numeric dump file is named on
the command line, the stack trace is read from the standard input.

*Note `resolve_stack_dump': resolve-stack-dump. supports the options
described in the following list.

   *  `--help', `-h'

     Display a help message and exit.

   *  `--numeric-dump-file=FILE_NAME', `-n FILE_NAME'

     Read the stack trace from the given file.

   *  `--symbols-file=FILE_NAME', `-s FILE_NAME'

     Use the given symbols file.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: programs-miscellaneous,  Prev: programs-development,  Up: programs

4.8 Miscellaneous Programs
==========================

* Menu:

* perror::                       `perror' --- Explain Error Codes
* replace-utility::              `replace' --- A String-Replacement Utility
* resolveip::                    `resolveip' --- Resolve Host name to IP Address or Vice Versa


File: manual.info,  Node: perror,  Next: replace-utility,  Prev: programs-miscellaneous,  Up: programs-miscellaneous

4.8.1 `perror' -- Explain Error Codes
-------------------------------------

For most system errors, MySQL displays, in addition to an internal text
message, the system error code in one of the following styles:

     message ... (errno: #)
     message ... (Errcode: #)

You can find out what the error code means by examining the
documentation for your system or by using the *Note `perror': perror.
utility.

*Note `perror': perror. prints a description for a system error code or
for a storage engine (table handler) error code.

Invoke *Note `perror': perror. like this:

     shell> perror [OPTIONS] ERRORCODE ...

Example:

     shell> perror 13 64
     OS error code  13:  Permission denied
     OS error code  64:  Machine is not on the network

Note that the meaning of system error messages may be dependent on your
operating system. A given error code may mean different things on
different operating systems.

*Note `perror': perror. supports the following options:

   *  `--help', `--info', `-I', `-?'

     Display a help message and exit.

   *  `--silent', `-s'

     Silent mode. Print only the error message.

   *  `--verbose', `-v'

     Verbose mode. Print error code and message. This is the default
     behavior.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: replace-utility,  Next: resolveip,  Prev: perror,  Up: programs-miscellaneous

4.8.2 `replace' -- A String-Replacement Utility
-----------------------------------------------

The *Note `replace': replace-utility. utility program changes strings
in place in files or on the standard input.

Invoke *Note `replace': replace-utility. in one of the following ways:

     shell> replace FROM TO [FROM TO] ... -- FILE_NAME [FILE_NAME] ...
     shell> replace FROM TO [FROM TO] ... < FILE_NAME

FROM represents a string to look for and TO represents its replacement.
There can be one or more pairs of strings.

Use the `--' option to indicate where the string-replacement list ends
and the file names begin. In this case, any file named on the command
line is modified in place, so you may want to make a copy of the
original before converting it. REPLACE prints a message indicating
which of the input files it actually modifies.

If the `--' option is not given, *Note `replace': replace-utility.
reads the standard input and writes to the standard output.

*Note `replace': replace-utility. uses a finite state machine to match
longer strings first. It can be used to swap strings. For example, the
following command swaps `a' and `b' in the given files, `file1' and
`file2':

     shell> replace a b b a -- file1 file2 ...

The *Note `replace': replace-utility. program is used by *Note
`msql2mysql': msql2mysql. See *Note msql2mysql::.

*Note `replace': replace-utility. supports the following options:

   *  `-?', `-I'

     Display a help message and exit.

   *  `-#DEBUG_OPTIONS'

     Enable debugging.

   *  `-s'

     Silent mode. Print less information what the program does.

   *  `-v'

     Verbose mode. Print more information about what the program does.

   *  `-V'

     Display version information and exit.


File: manual.info,  Node: resolveip,  Prev: replace-utility,  Up: programs-miscellaneous

4.8.3 `resolveip' -- Resolve Host name to IP Address or Vice Versa
------------------------------------------------------------------

The *Note `resolveip': resolveip. utility resolves host names to IP
addresses and vice versa.

Invoke *Note `resolveip': resolveip. like this:

     shell> resolveip [OPTIONS] {HOST_NAME|IP-ADDR} ...

*Note `resolveip': resolveip. supports the options described in the
following list.

   *  `--help', `--info', `-?', `-I'

     Display a help message and exit.

   *  `--silent', `-s'

     Silent mode. Produce less output.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: server-administration,  Next: backup-and-recovery,  Prev: programs,  Up: Top

5 MySQL Server Administration
*****************************

* Menu:

* mysqld-server::                The MySQL Server
* server-logs::                  MySQL Server Logs
* security::                     General Security Issues
* privilege-system::             The MySQL Access Privilege System
* user-account-management::      MySQL User Account Management
* multiple-servers::             Running Multiple MySQL Servers on the Same Machine
* dba-dtrace-server::            Tracing `mysqld' Using DTrace

MySQL Server (*Note `mysqld': mysqld.) is the main program that does
most of the work in a MySQL installation. This section provides an
overview of MySQL Server and covers topics that deal with administering
a MySQL installation:

   * Server configuration

   * The server log files

   * Security issues and user-account management

   * Management of multiple servers on a single machine


File: manual.info,  Node: mysqld-server,  Next: server-logs,  Prev: server-administration,  Up: server-administration

5.1 The MySQL Server
====================

* Menu:

* mysqld-option-tables::         Server Option and Variable Reference
* server-options::               Server Command Options
* server-system-variables::      Server System Variables
* server-session-variables::     Session System Variables
* using-system-variables::       Using System Variables
* server-status-variables::      Server Status Variables
* server-sql-mode::              Server SQL Modes
* server-side-help-support::     Server-Side Help
* server-signal-response::       Server Response to Signals
* server-shutdown::              The Shutdown Process

*Note `mysqld': mysqld. is the MySQL server. The following discussion
covers these MySQL server configuration topics:

   * Startup options that the server supports

   * Server system variables

   * Server status variables

   * How to set the server SQL mode

   * The server shutdown process

*Note*:

Not all storage engines are supported by all MySQL server binaries and
configurations. To find out how to determine which storage engines are
supported by your MySQL server installation, see *Note show-engines::.


File: manual.info,  Node: mysqld-option-tables,  Next: server-options,  Prev: mysqld-server,  Up: mysqld-server

5.1.1 Server Option and Variable Reference
------------------------------------------

The following table provides a list of all the command line options,
server and status variables applicable within `mysqld'.

The table lists command-line options (Cmd-line), options valid in
configuration files (Option file), server system variables (System
Var), and status variables (Status var) in one unified list, with
notification of where each option/variable is valid. If a server option
set on the command line or in an option file differs from the name of
the corresponding server system or status variable, the variable name
is noted immediately below the corresponding option. For status
variables, the scope of the variable is shown (Scope) as either global,
session, or both. Please see the corresponding sections for details on
setting and using the options and variables. Where appropriate, a
direct link to further information on the item as available.

*`mysqld' Option/Variable Summary*

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
abort-slave-event-count       Yes                                                        Yes                                                                                                                                                                                                                                         
Aborted_clients                                                                                                                                                                                                Yes                                                        Global                                                     No
Aborted_connects                                                                                                                                                                                               Yes                                                        Global                                                     No
allow-suspicious-udfs         Yes                                                        Yes                                                                                                                                                                                                                                         
ansi                          Yes                                                        Yes                                                                                                                                                                                                                                         
auto_increment_increment      Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
auto_increment_offset         Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
autocommit                                                                                                                                          Yes                                                                                                                   Session                                                    Yes
automatic_sp_privileges                                                                                                                             Yes                                                                                                                   Global                                                     Yes
back_log                      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
backup_history_log            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
backup_history_log_file       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
backup_progress_log           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
backup_progress_log_file      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
backup_wait_timeout                                                                                                                                 Yes                                                                                                                   Session                                                    Yes
backupdir                     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
basedir                       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
big-tables                    Yes                                                        Yes                                                                                                                                                                              Session                                                    Yes
- _Variable_: big_tables                                                                                                                            Yes                                                                                                                   Session                                                    Yes
bind-address                  Yes                                                        Yes                                                                                                                                                                                                                                         
Binlog_cache_disk_use                                                                                                                                                                                          Yes                                                        Global                                                     No
binlog_cache_size             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Binlog_cache_use                                                                                                                                                                                               Yes                                                        Global                                                     No
binlog-do-db                  Yes                                                        Yes                                                                                                                                                                                                                                         
binlog-format                 Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: binlog_format                                                                                                                         Yes                                                                                                                   Both                                                       Yes
binlog-ignore-db              Yes                                                        Yes                                                                                                                                                                                                                                         
binlog-row-event-max-size     Yes                                                        Yes                                                                                                                                                                                                                                         
bootstrap                     Yes                                                        Yes                                                                                                                                                                                                                                         
bulk_insert_buffer_size       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Bytes_received                                                                                                                                                                                                 Yes                                                        Both                                                       No
Bytes_sent                                                                                                                                                                                                     Yes                                                        Both                                                       No
character_set_client                                                                                                                                Yes                                                                                                                   Both                                                       Yes
character-set-client-handshakeYes                                                        Yes                                                                                                                                                                                                                                         
character_set_connection                                                                                                                            Yes                                                                                                                   Both                                                       Yes
character_set_database This                                                                                                                         Yes                                                                                                                   Both                                                       Yes
option is dynamic, but only                                                                                                                                                                                                                                                                                                          
the server should set this                                                                                                                                                                                                                                                                                                           
information. You should not                                                                                                                                                                                                                                                                                                          
set the value of this                                                                                                                                                                                                                                                                                                                
variable manually.                                                                                                                                                                                                                                                                                                                   
character-set-filesystem      Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
character_set_filesystem                                                                                                                                                                                                                                                                                                             
character_set_results                                                                                                                               Yes                                                                                                                   Both                                                       Yes
character-set-server          Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
character_set_server                                                                                                                                                                                                                                                                                                                 
character_set_system                                                                                                                                Yes                                                                                                                   Global                                                     No
character-sets-dir            Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
character_sets_dir                                                                                                                                                                                                                                                                                                                   
chroot                        Yes                                                        Yes                                                                                                                                                                                                                                         
collation_connection                                                                                                                                Yes                                                                                                                   Both                                                       Yes
collation_database This                                                                                                                             Yes                                                                                                                   Both                                                       Yes
option is dynamic, but only                                                                                                                                                                                                                                                                                                          
the server should set this                                                                                                                                                                                                                                                                                                           
information. You should not                                                                                                                                                                                                                                                                                                          
set the value of this                                                                                                                                                                                                                                                                                                                
variable manually.                                                                                                                                                                                                                                                                                                                   
collation-server              Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
collation_server                                                                                                                                                                                                                                                                                                                     
Com_admin_commands                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_alter_db                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_alter_event                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_alter_table                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_analyze                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_backup                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_backup_table                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_begin                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_call_procedure                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_change_db                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_change_master                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_check                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_checksum                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_commit                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_create_db                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_create_event                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_create_function                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_create_index                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_create_table                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_create_user                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_dealloc_sql                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_delete                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_delete_multi                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_do                                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_drop_db                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_drop_event                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_drop_function                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_drop_index                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_drop_table                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_drop_user                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_execute_sql                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_flush                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_grant                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_ha_close                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_ha_open                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_ha_read                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_help                                                                                                                                                                                                       Yes                                                        Both                                                       No
Com_insert                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_insert_select                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_kill                                                                                                                                                                                                       Yes                                                        Both                                                       No
Com_load                                                                                                                                                                                                       Yes                                                        Both                                                       No
Com_lock_tables                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_optimize                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_preload_keys                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_prepare_sql                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_purge                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_purge_before_date                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_rename_table                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_repair                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_replace                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_replace_select                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_reset                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_restore                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_restore_table                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_revoke                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_revoke_all                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_rollback                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_savepoint                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_select                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_set_option                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_show_binlog_events                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_binlogs                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_show_charsets                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_show_collations                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_show_column_types                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_show_create_db                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_show_create_event                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_show_create_table                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_show_databases                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_show_engine_logs                                                                                                                                                                                           Yes                                                        Both                                                       No
Com_show_engine_mutex                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_show_engine_status                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_errors                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_events                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_fields                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_grants                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_innodb_status                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_keys                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_show_logs                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_show_master_status                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_ndb_status                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_show_new_master                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_show_open_tables                                                                                                                                                                                           Yes                                                        Both                                                       No
Com_show_plugins                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_show_privileges                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_show_processlist                                                                                                                                                                                           Yes                                                        Both                                                       No
Com_show_profile                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_show_profiles                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_show_slave_hosts                                                                                                                                                                                           Yes                                                        Both                                                       No
Com_show_slave_status                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_show_status                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_storage_engines                                                                                                                                                                                       Yes                                                        Both                                                       No
Com_show_tables                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_triggers                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_show_variables                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_show_warnings                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_slave_start                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_slave_stop                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_stmt_close                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_stmt_execute                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_stmt_fetch                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_stmt_prepare                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_stmt_reprepare                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_stmt_reset                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_stmt_send_long_data                                                                                                                                                                                        Yes                                                        Both                                                       No
Com_truncate                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_unlock_tables                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_update                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_update_multi                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_xa_commit                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_xa_end                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_xa_prepare                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_xa_recover                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_xa_rollback                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_xa_start                                                                                                                                                                                                   Yes                                                        Both                                                       No
completion_type               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Compression                                                                                                                                                                                                    Yes                                                        Session                                                    No
concurrent_insert             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
connect_timeout               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Connections                                                                                                                                                                                                    Yes                                                        Global                                                     No
console                       Yes                                                        Yes                                                                                                                                                                                                                                         
core-file                     Yes                                                        Yes                                                                                                                                                                                                                                         
Created_tmp_disk_tables                                                                                                                                                                                        Yes                                                        Both                                                       No
Created_tmp_files                                                                                                                                                                                              Yes                                                        Global                                                     No
Created_tmp_tables                                                                                                                                                                                             Yes                                                        Both                                                       No
datadir                       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
date_format                                                                                                                                         Yes                                                                                                                   Both                                                       Yes
datetime_format               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
debug                         Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
debug_sync                                                                                                                                          Yes                                                                                                                   Both                                                       Yes
debug-sync-timeout            Yes                                                        Yes                                                                                                                                                                                                                                         
default-storage-engine        Yes                                                        Yes                                                                                                                                                                                                                                         
default-table-type            Yes                                                        Yes                                                                                                                                                                                                                                         
default-time-zone             Yes                                                        Yes                                                                                                                                                                                                                                         
default_week_format           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
defaults-extra-file           Yes                                                                                                                                                                                                                                                                                                    
defaults-file                 Yes                                                                                                                                                                                                                                                                                                    
defaults-group-suffix         Yes                                                                                                                                                                                                                                                                                                    
delay-key-write               Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: delay_key_write                                                                                                                       Yes                                                                                                                   Global                                                     Yes
Delayed_errors                                                                                                                                                                                                 Yes                                                        Global                                                     No
delayed_insert_limit          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Delayed_insert_threads                                                                                                                                                                                         Yes                                                        Global                                                     No
delayed_insert_timeout        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
delayed_queue_size            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Delayed_writes                                                                                                                                                                                                 Yes                                                        Global                                                     No
des-key-file                  Yes                                                        Yes                                                                                                                                                                                                                                         
disconnect-slave-event-count  Yes                                                        Yes                                                                                                                                                                                                                                         
div_precision_increment       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
enable-locking                Yes                                                        Yes                                                                                                                                                                                                                                         
enable-named-pipe             Yes                                                        Yes                                                                                                                                                                                                                                         
enable-pstack                 Yes                                                        Yes                                                                                                                                                                                                                                         
engine-condition-pushdown     Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
engine_condition_pushdown                                                                                                                                                                                                                                                                                                            
error_count                                                                                                                                         Yes                                                                                                                   Session                                                    No
event-scheduler               Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: event_scheduler                                                                                                                       Yes                                                                                                                   Global                                                     Yes
exit-info                     Yes                                                        Yes                                                                                                                                                                                                                                         
expire_logs_days              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
external-locking              Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_:                                                                                                                                                                                                                                                                                                                        
external_locking                                                                                                                                                                                                                                                                                                                     
falcon                        Yes                                                        Yes                                                                                                                                                                                                                                         
falcon_checkpoint_schedule    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_checksums              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_consistent_read        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
falcon_debug_mask             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_debug_server           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_disable_fsync          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_gopher_threads         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_index_chill_threshold  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_initial_allocation     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_io_threads             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_large_blob_threshold   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_lock_wait_timeout      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_max_transaction_backlogYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_page_cache_size        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_page_size              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_record_chill_threshold Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_record_memory_max      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_record_scavenge_floor  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_record_scavenge_thresholdYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_scavenge_schedule      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_serial_log_buffers     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_serial_log_dir         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_serial_log_priority    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_support_xa             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_use_deferred_index_hashYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_use_sectorcache        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_use_supernodes         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
flush                         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Flush_commands                                                                                                                                                                                                 Yes                                                        Global                                                     No
flush_time                    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
foreign_key_checks                                                                                                                                  Yes                                                                                                                   Session                                                    Yes
ft_boolean_syntax             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
ft_max_word_len               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
ft_min_word_len               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
ft_query_expansion_limit      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
ft_stopword_file              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
gdb                           Yes                                                        Yes                                                                                                                                                                                                                                         
general-log                   Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: general_log                                                                                                                           Yes                                                                                                                   Global                                                     Yes
general_log_file              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
group_concat_max_len          Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Handler_commit                                                                                                                                                                                                 Yes                                                        Both                                                       No
Handler_delete                                                                                                                                                                                                 Yes                                                        Both                                                       No
Handler_discover                                                                                                                                                                                               Yes                                                        Both                                                       No
Handler_prepare                                                                                                                                                                                                Yes                                                        Both                                                       No
Handler_read_first                                                                                                                                                                                             Yes                                                        Both                                                       No
Handler_read_key                                                                                                                                                                                               Yes                                                        Both                                                       No
Handler_read_next                                                                                                                                                                                              Yes                                                        Both                                                       No
Handler_read_prev                                                                                                                                                                                              Yes                                                        Both                                                       No
Handler_read_rnd                                                                                                                                                                                               Yes                                                        Both                                                       No
Handler_read_rnd_next                                                                                                                                                                                          Yes                                                        Both                                                       No
Handler_rollback                                                                                                                                                                                               Yes                                                        Both                                                       No
Handler_savepoint                                                                                                                                                                                              Yes                                                        Both                                                       No
Handler_savepoint_rollback                                                                                                                                                                                     Yes                                                        Both                                                       No
Handler_update                                                                                                                                                                                                 Yes                                                        Both                                                       No
Handler_write                                                                                                                                                                                                  Yes                                                        Both                                                       No
have_compress                                                                                                                                       Yes                                                                                                                   Global                                                     No
have_crypt                                                                                                                                          Yes                                                                                                                   Global                                                     No
have_csv                                                                                                                                            Yes                                                                                                                   Global                                                     No
have_dynamic_loading                                                                                                                                Yes                                                                                                                   Global                                                     No
have_geometry                                                                                                                                       Yes                                                                                                                   Global                                                     No
have_innodb                                                                                                                                         Yes                                                                                                                   Global                                                     No
have_ndbcluster                                                                                                                                     Yes                                                                                                                   Global                                                     No
have_openssl                                                                                                                                        Yes                                                                                                                   Global                                                     No
have_partitioning                                                                                                                                   Yes                                                                                                                   Global                                                     No
have_query_cache                                                                                                                                    Yes                                                                                                                   Global                                                     No
have_rtree_keys                                                                                                                                     Yes                                                                                                                   Global                                                     No
have_ssl                                                                                                                                            Yes                                                                                                                   Global                                                     No
have_symlink                                                                                                                                        Yes                                                                                                                   Global                                                     No
help                          Yes                                                        Yes                                                                                                                                                                                                                                         
hostname                                                                                                                                            Yes                                                                                                                   Global                                                     No
identity                                                                                                                                            Yes                                                                                                                   Session                                                    Yes
init_connect                  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
init-file                     Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: init_file                                                                                                                             Yes                                                                                                                   Global                                                     No
init_slave                    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb                        Yes                                                        Yes                                                                                                                                                                                                                                         
innodb_adaptive_hash_index    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_additional_mem_pool_sizeYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_autoextend_increment   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_autoinc_lock_mode      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_buffer_pool_pages_data                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_dirty                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_flushed                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_free                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_latched                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_misc                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_total                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_ahead_rnd                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_ahead_seq                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_requests                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_reads                                                                                                                                                                                       Yes                                                        Global                                                     No
innodb_buffer_pool_size       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_buffer_pool_wait_free                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_buffer_pool_write_requests                                                                                                                                                                                 Yes                                                        Global                                                     No
innodb_checksums              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_commit_concurrency     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_concurrency_tickets    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_data_file_path         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_data_fsyncs                                                                                                                                                                                             Yes                                                        Global                                                     No
innodb_data_home_dir          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_data_pending_fsyncs                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_data_pending_reads                                                                                                                                                                                      Yes                                                        Global                                                     No
Innodb_data_pending_writes                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_data_read                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_data_reads                                                                                                                                                                                              Yes                                                        Global                                                     No
Innodb_data_writes                                                                                                                                                                                             Yes                                                        Global                                                     No
Innodb_data_written                                                                                                                                                                                            Yes                                                        Global                                                     No
Innodb_dblwr_pages_written                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_dblwr_writes                                                                                                                                                                                            Yes                                                        Global                                                     No
innodb_doublewrite            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_fast_shutdown          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_file_io_threads        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_file_per_table         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_flush_log_at_trx_commitYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_flush_method           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_force_recovery         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_lock_wait_timeout      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_locks_unsafe_for_binlogYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_buffer_size        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_file_size          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_files_in_group     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_group_home_dir     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_log_waits                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_log_write_requests                                                                                                                                                                                      Yes                                                        Global                                                     No
Innodb_log_writes                                                                                                                                                                                              Yes                                                        Global                                                     No
innodb_max_dirty_pages_pct    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_max_purge_lag          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_mirrored_log_groups    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_open_files             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_os_log_fsyncs                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_os_log_pending_fsyncs                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_os_log_pending_writes                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_os_log_written                                                                                                                                                                                          Yes                                                        Global                                                     No
Innodb_page_size                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_pages_created                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_pages_read                                                                                                                                                                                              Yes                                                        Global                                                     No
Innodb_pages_written                                                                                                                                                                                           Yes                                                        Global                                                     No
innodb_rollback_on_timeout    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_row_lock_current_waits                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_row_lock_time                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_row_lock_time_avg                                                                                                                                                                                       Yes                                                        Global                                                     No
Innodb_row_lock_time_max                                                                                                                                                                                       Yes                                                        Global                                                     No
Innodb_row_lock_waits                                                                                                                                                                                          Yes                                                        Global                                                     No
Innodb_rows_deleted                                                                                                                                                                                            Yes                                                        Global                                                     No
Innodb_rows_inserted                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_rows_read                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_rows_updated                                                                                                                                                                                            Yes                                                        Global                                                     No
innodb_stats_on_metadata      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_status_file            Yes                                                        Yes                                                                                                                                                                                                                                         
innodb_support_xa             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
innodb_sync_spin_loops        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_table_locks            Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
innodb_thread_concurrency     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_thread_sleep_delay     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
insert_id                                                                                                                                           Yes                                                                                                                   Session                                                    Yes
interactive_timeout           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
join_buffer_size              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
join_cache_level              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
keep_files_on_create          Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Key_blocks_not_flushed                                                                                                                                                                                         Yes                                                        Global                                                     No
Key_blocks_unused                                                                                                                                                                                              Yes                                                        Global                                                     No
Key_blocks_used                                                                                                                                                                                                Yes                                                        Global                                                     No
key_buffer_size               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
key_cache_age_threshold       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
key_cache_block_size          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
key_cache_division_limit      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Key_read_requests                                                                                                                                                                                              Yes                                                        Global                                                     No
Key_reads                                                                                                                                                                                                      Yes                                                        Global                                                     No
Key_write_requests                                                                                                                                                                                             Yes                                                        Global                                                     No
Key_writes                                                                                                                                                                                                     Yes                                                        Global                                                     No
language                      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
large_page_size                                                                                                                                     Yes                                                                                                                   Global                                                     No
large-pages                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: large_pages                                                                                                                           Yes                                                                                                                   Global                                                     No
last_insert_id                                                                                                                                      Yes                                                                                                                   Session                                                    Yes
Last_query_cost                                                                                                                                                                                                Yes                                                        Session                                                    No
lc_time_names                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
license                                                                                                                                             Yes                                                                                                                   Global                                                     No
local_infile                                                                                                                                        Yes                                                                                                                   Global                                                     Yes
local-infile                  Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_: local_infile                                                                                                                                                                                                                                                                                                           
locked_in_memory                                                                                                                                    Yes                                                                                                                   Global                                                     No
log                           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
log-backup-output             Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
log_backup_output                                                                                                                                                                                                                                                                                                                    
log_bin                                                                                                                                             Yes                                                                                                                   Global                                                     No
log-bin                       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
log-bin-index                 Yes                                                        Yes                                                                                                                                                                                                                                         
log-bin-trust-function-creatorsYes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
log_bin_trust_function_creators                                                                                                                                                                                                                                                                                                       
log-error                     Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: log_error                                                                                                                             Yes                                                                                                                   Global                                                     No
log-isam                      Yes                                                        Yes                                                                                                                                                                                                                                         
log-output                    Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: log_output                                                                                                                            Yes                                                                                                                   Global                                                     Yes
log-queries-not-using-indexes Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
log_queries_not_using_indexes                                                                                                                                                                                                                                                                                                        
log-short-format              Yes                                                        Yes                                                                                                                                                                                                                                         
log-slave-updates             Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
log_slave_updates                                                                                                                                                                                                                                                                                                                    
log-slow-admin-statements     Yes                                                        Yes                                                                                                                                                                                                                                         
log-slow-queries              Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
log_slow_queries                                                                                                                                                                                                                                                                                                                     
log-slow-slave-statements     Yes                                                        Yes                                                                                                                                                                                                                                         
log-tc                        Yes                                                        Yes                                                                                                                                                                                                                                         
log-tc-size                   Yes                                                        Yes                                                                                                                                                                                                                                         
log-warnings                  Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: log_warnings                                                                                                                          Yes                                                                                                                   Both                                                       Yes
long_query_time               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
low-priority-updates          Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
low_priority_updates                                                                                                                                                                                                                                                                                                                 
lower_case_file_system        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
lower_case_table_names        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
maria                         Yes                                                        Yes                                                                                                                                                                                                                                         
maria-block-size              Yes                                                        Yes                                                                                                                                                                                                                                         No
- _Variable_:                                                                                                                                       Yes                                                                                                                                                                              No
maria_block_size                                                                                                                                                                                                                                                                                                                     
maria-checkpoint-interval     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
maria-force-start-after-recovery-failuresYes                                                        Yes                                                                                                                                                                                                                                         
maria-log-dir-path            Yes                                                        Yes                                                                                                                                                                                                                                         
maria-log-file-size           Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_log_file_size                                                                                                                                                                                                                                                                                                                  
maria-log-purge-type          Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_log_purge_type                                                                                                                                                                                                                                                                                                                 
maria-max-sort-file-size      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
maria-page-checksum           Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_page_checksum                                                                                                                                                                                                                                                                                                                  
maria-pagecache-age-threshold Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_pagecache_age_threshold                                                                                                                                                                                                                                                                                                        
maria-pagecache-buffer-size   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
maria_pagecache_buffer_size                                                                                                                                                                                                                                                                                                          
maria-pagecache-division-limitYes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_pagecache_division_limit                                                                                                                                                                                                                                                                                                       
maria-recover                 Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: maria_recover                                                                                                                         Yes                                                                                                                   Global                                                     Yes
maria-repair-threads          Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
maria_repair_threads                                                                                                                                                                                                                                                                                                                 
maria-sort-buffer-size        Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
maria_sort_buffer_size                                                                                                                                                                                                                                                                                                               
maria-stats-method            Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
maria_stats_method                                                                                                                                                                                                                                                                                                                   
maria-sync-log-dir            Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_sync_log_dir                                                                                                                                                                                                                                                                                                                   
*Note master-bind:            Yes                                                        Yes                                                        Yes                                                                                                                                                                              No
replication-options.                                                                                                                                                                                                                                                                                                                 
master-info-file              Yes                                                        Yes                                                                                                                                                                                                                                         
master-retry-count            Yes                                                        Yes                                                                                                                                                                                                                                         
max_allowed_packet            Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_binlog_cache_size         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max-binlog-dump-events        Yes                                                        Yes                                                                                                                                                                                                                                         
max_binlog_size               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max_connect_errors            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max_connections               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max_delayed_threads           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_error_count               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_heap_table_size           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_insert_delayed_threads                                                                                                                          Yes                                                                                                                   Both                                                       Yes
max_join_size                 Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_length_for_sort_data      Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_prepared_stmt_count       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max_relay_log_size            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max_seeks_for_key             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_sort_length               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_sp_recursion_depth        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_tmp_tables                Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Max_used_connections                                                                                                                                                                                           Yes                                                        Global                                                     No
max_user_connections          Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_write_lock_count          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
memlock                       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
min-examined-row-limit        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam-block-size             Yes                                                        Yes                                                                                                                                                                                                                                         
myisam_data_pointer_size      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
myisam_max_sort_file_size     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
myisam-recover                Yes                                                        Yes                                                                                                                                                                                                                                         
myisam_recover_options                                                                                                                              Yes                                                                                                                   Global                                                     No
myisam_repair_threads         Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_sort_buffer_size       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_stats_method           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_use_mmap               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
named_pipe                                                                                                                                          Yes                                                                                                                   Global                                                     No
ndb_autoincrement_prefetch_sz Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Ndb_cluster_node_id                                                                                                                                                                                            Yes                                                        Both                                                       No
Ndb_config_from_host                                                                                                                                                                                           Yes                                                        Both                                                       No
Ndb_config_from_port                                                                                                                                                                                           Yes                                                        Both                                                       No
Ndb_conflict_fn_max                                                                                                                                                                                            Yes                                                        Global                                                     No
Ndb_conflict_fn_old                                                                                                                                                                                            Yes                                                        Global                                                     No
ndb_index_stat_cache_entries  Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_index_stat_enable         Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_index_stat_update_freq    Yes                                                        Yes                                                                                                                                                                                                                                         
Ndb_number_of_data_nodes                                                                                                                                                                                       Yes                                                        Global                                                     No
ndb_report_thresh_binlog_epoch_slipYes                                                        Yes                                                                                                                                                                                                                                         
ndb_report_thresh_binlog_mem_usageYes                                                        Yes                                                                                                                                                                                                                                         
ndb_use_transactions          Yes                                                        Yes                                                                                                                                                                                                                                         
net_buffer_length             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
net_read_timeout              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
net_retry_count               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
net_write_timeout             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
new                           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
no-defaults                   Yes                                                                                                                                                                                                                                                                                                    
Not_flushed_delayed_rows                                                                                                                                                                                       Yes                                                        Global                                                     No
old                           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
old-alter-table               Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_: old_alter_table                                                                                                                                                                                                                                                                                                        
old-passwords                 Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: old_passwords                                                                                                                         Yes                                                                                                                   Both                                                       Yes
old-style-user-limits         Yes                                                        Yes                                                                                                                                                                                                                                         
one-thread                    Yes                                                        Yes                                                                                                                                                                                                                                         
Open_files                                                                                                                                                                                                     Yes                                                        Global                                                     No
open-files-limit              Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
open_files_limit                                                                                                                                                                                                                                                                                                                     
Open_streams                                                                                                                                                                                                   Yes                                                        Global                                                     No
Open_table_definitions                                                                                                                                                                                         Yes                                                        Global                                                     No
Open_tables                                                                                                                                                                                                    Yes                                                        Both                                                       No
Opened_files                                                                                                                                                                                                   Yes                                                        Global                                                     No
Opened_table_definitions                                                                                                                                                                                       Yes                                                        Both                                                       No
Opened_tables                                                                                                                                                                                                  Yes                                                        Both                                                       No
optimizer_prune_level         Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
optimizer_search_depth        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
optimizer_switch              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
optimizer_use_mrr                                                                                                                                   Yes                                                                                                                   Both                                                       Yes
pid-file                      Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: pid_file                                                                                                                              Yes                                                                                                                   Global                                                     No
plugin_dir                    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin-load                   Yes                                                        Yes                                                                                                                                                                                                                                         
port                          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
port-open-timeout             Yes                                                        Yes                                                                                                                                                                                                                                         
preload_buffer_size           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
prepared_stmt_count                                                                                                                                 Yes                                                        Yes                                                        Global                                                     No
print-defaults                Yes                                                                                                                                                                                                                                                                                                    
profiling                                                                                                                                           Yes                                                                                                                   Session                                                    Yes
profiling_history_size                                                                                                                              Yes                                                                                                                   Both                                                       Yes
protocol_version                                                                                                                                    Yes                                                                                                                   Global                                                     No
Qcache_free_blocks                                                                                                                                                                                             Yes                                                        Global                                                     No
Qcache_free_memory                                                                                                                                                                                             Yes                                                        Global                                                     No
Qcache_hits                                                                                                                                                                                                    Yes                                                        Global                                                     No
Qcache_inserts                                                                                                                                                                                                 Yes                                                        Global                                                     No
Qcache_lowmem_prunes                                                                                                                                                                                           Yes                                                        Global                                                     No
Qcache_not_cached                                                                                                                                                                                              Yes                                                        Global                                                     No
Qcache_queries_in_cache                                                                                                                                                                                        Yes                                                        Global                                                     No
Qcache_total_blocks                                                                                                                                                                                            Yes                                                        Global                                                     No
Queries                                                                                                                                                                                                        Yes                                                        Both                                                       No
query_alloc_block_size        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
query_cache_limit             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
query_cache_min_res_unit      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
query_cache_size              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
query_cache_type              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
query_cache_wlock_invalidate  Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
query_prealloc_size           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Questions                                                                                                                                                                                                      Yes                                                        Both                                                       No
rand_seed1                                                                                                                                          Yes                                                                                                                   Session                                                    Yes
rand_seed2                                                                                                                                          Yes                                                                                                                   Session                                                    Yes
range_alloc_block_size        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
read_buffer_size              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
read_only                     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
read_rnd_buffer_size          Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
relay-log                     Yes                                                        Yes                                                                                                                                                                                                                                         
relay-log-index               Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_: relay_log_index                                                                                                                                                                                                                                                                                                        
relay-log-info-file           Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_:                                                                                                                                                                                                                                                                                                                        
relay_log_info_file                                                                                                                                                                                                                                                                                                                  
relay_log_purge               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
relay_log_recovery            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
relay_log_space_limit         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
replicate-do-db               Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-do-table            Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-ignore-db           Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-ignore-table        Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-rewrite-db          Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-same-server-id      Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-wild-do-table       Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-wild-ignore-table   Yes                                                        Yes                                                                                                                                                                                                                                         
report-host                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_host                                                                                                                           Yes                                                                                                                   Global                                                     No
report-password               Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_password                                                                                                                       Yes                                                                                                                   Global                                                     No
report-port                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_port                                                                                                                           Yes                                                                                                                   Global                                                     No
report-user                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_user                                                                                                                           Yes                                                                                                                   Global                                                     No
rpl_recovery_rank                                                                                                                                   Yes                                                                                                                   Global                                                     Yes
Rpl_semi_sync_master_clients                                                                                                                                                                                   Yes                                                        Global                                                     No
rpl_semi_sync_master_enabled                                                                                                                        Yes                                                                                                                   Global                                                     Yes
Rpl_semi_sync_master_net_avg_wait_time                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_net_wait_time                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_net_waits                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_no_times                                                                                                                                                                                  Yes                                                        Global                                                     No
Rpl_semi_sync_master_no_tx                                                                                                                                                                                     Yes                                                        Global                                                     No
rpl_semi_sync_master_reply_log_file_pos                                                                                                                      Yes                                                                                                                   Global                                                     Yes
Rpl_semi_sync_master_status                                                                                                                                                                                    Yes                                                        Global                                                     No
Rpl_semi_sync_master_timefunc_failures                                                                                                                                                                                 Yes                                                        Global                                                     No
rpl_semi_sync_master_timeout                                                                                                                        Yes                                                                                                                   Global                                                     Yes
rpl_semi_sync_master_trace_level                                                                                                                      Yes                                                                                                                   Global                                                     Yes
Rpl_semi_sync_master_tx_avg_wait_time                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_tx_wait_time                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_tx_waits                                                                                                                                                                                  Yes                                                        Global                                                     No
Rpl_semi_sync_master_wait_pos_backtraverse                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_wait_sessions                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_yes_tx                                                                                                                                                                                    Yes                                                        Global                                                     No
rpl_semi_sync_slave_enabled                                                                                                                         Yes                                                                                                                   Global                                                     Yes
Rpl_semi_sync_slave_status                                                                                                                                                                                     Yes                                                        Global                                                     No
rpl_semi_sync_slave_trace_level                                                                                                                      Yes                                                                                                                   Global                                                     Yes
Rpl_status                                                                                                                                                                                                     Yes                                                        Global                                                     No
safe-mode                     Yes                                                        Yes                                                                                                                                                                                                                                         
safe-user-create              Yes                                                        Yes                                                                                                                                                                                                                                         
safemalloc-mem-limit          Yes                                                        Yes                                                                                                                                                                                                                                         
secure-auth                   Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: secure_auth                                                                                                                           Yes                                                                                                                   Global                                                     Yes
secure-backup-file-priv       Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
secure_backup_file_priv                                                                                                                                                                                                                                                                                                              
secure-file-priv              Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
secure_file_priv                                                                                                                                                                                                                                                                                                                     
Select_full_join                                                                                                                                                                                               Yes                                                        Both                                                       No
Select_full_range_join                                                                                                                                                                                         Yes                                                        Both                                                       No
Select_range                                                                                                                                                                                                   Yes                                                        Both                                                       No
Select_range_check                                                                                                                                                                                             Yes                                                        Both                                                       No
Select_scan                                                                                                                                                                                                    Yes                                                        Both                                                       No
server-id                     Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: server_id                                                                                                                             Yes                                                                                                                   Global                                                     Yes
shared_memory                                                                                                                                       Yes                                                                                                                   Global                                                     No
shared_memory_base_name                                                                                                                             Yes                                                                                                                   Global                                                     No
show-slave-auth-info          Yes                                                        Yes                                                                                                                                                                                                                                         
skip-character-set-client-handshakeYes                                                        Yes                                                                                                                                                                                                                                         
skip-concurrent-insert        Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_:                                                                                                                                                                                                                                                                                                                        
concurrent_insert                                                                                                                                                                                                                                                                                                                    
skip-external-locking         Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
skip_external_locking                                                                                                                                                                                                                                                                                                                
skip-falcon                   Yes                                                        Yes                                                                                                                                                                                                                                         
skip-grant-tables             Yes                                                        Yes                                                                                                                                                                                                                                         
skip-host-cache               Yes                                                        Yes                                                                                                                                                                                                                                         
skip-innodb                   Yes                                                        Yes                                                                                                                                                                                                                                         
skip-innodb-checksums         Yes                                                        Yes                                                                                                                                                                                                                                         
skip-locking                  Yes                                                        Yes                                                                                                                                                                                                                                         
skip-log-warnings             Yes                                                                                                                                                                                                                                                                                                    
skip-name-resolve             Yes                                                        Yes                                                                                                                                                                                                                                         
skip-ndbcluster               Yes                                                        Yes                                                                                                                                                                                                                                         
skip-networking               Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: skip_networking                                                                                                                       Yes                                                                                                                   Global                                                     No
skip-new                      Yes                                                        Yes                                                                                                                                                                                                                                         
skip-safemalloc               Yes                                                        Yes                                                                                                                                                                                                                                         
skip-show-database            Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
skip_show_database                                                                                                                                                                                                                                                                                                                   
*Note skip-slave-start:       Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
skip-ssl                      Yes                                                        Yes                                                                                                                                                                                                                                         
skip-stack-trace              Yes                                                        Yes                                                                                                                                                                                                                                         
skip-symbolic-links           Yes                                                                                                                                                                                                                                                                                                    
skip-symlink                  Yes                                                        Yes                                                                                                                                                                                                                                         
skip-thread-priority          Yes                                                        Yes                                                                                                                                                                                                                                         
slave_compressed_protocol     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
slave_exec_mode                                                                                                                                     Yes                                                                                                                   Global                                                     Yes
Slave_heartbeat_period                                                                                                                                                                                         Yes                                                        Global                                                     No
*Note slave-load-tmpdir:      Yes                                                        Yes                                                                                                                                                                              Global                                                     No
replication-options.                                                                                                                                                                                                                                                                                                                 
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
slave_load_tmpdir                                                                                                                                                                                                                                                                                                                    
slave-net-timeout             Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
slave_net_timeout                                                                                                                                                                                                                                                                                                                    
Slave_open_temp_tables                                                                                                                                                                                         Yes                                                        Global                                                     No
Slave_received_heartbeats                                                                                                                                                                                      Yes                                                        Global                                                     No
Slave_retried_transactions                                                                                                                                                                                     Yes                                                        Global                                                     No
Slave_running                                                                                                                                                                                                  Yes                                                        Global                                                     No
slave-skip-errors             Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
slave_skip_errors                                                                                                                                                                                                                                                                                                                    
slave_transaction_retries     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Slow_launch_threads                                                                                                                                                                                            Yes                                                        Both                                                       No
slow_launch_time              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Slow_queries                                                                                                                                                                                                   Yes                                                        Both                                                       No
slow-query-log                Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: slow_query_log                                                                                                                        Yes                                                                                                                   Global                                                     Yes
slow_query_log_file           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
socket                        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
sort_buffer_size              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Sort_merge_passes                                                                                                                                                                                              Yes                                                        Both                                                       No
Sort_range                                                                                                                                                                                                     Yes                                                        Both                                                       No
Sort_rows                                                                                                                                                                                                      Yes                                                        Both                                                       No
Sort_scan                                                                                                                                                                                                      Yes                                                        Both                                                       No
sporadic-binlog-dump-fail     Yes                                                        Yes                                                                                                                                                                                                                                         
sql_auto_is_null                                                                                                                                    Yes                                                                                                                   Session                                                    Yes
sql_big_selects                                                                                                                                     Yes                                                                                                                   Session                                                    Yes
sql_big_tables                                                                                                                                      Yes                                                                                                                   Session                                                    Yes
sql_buffer_result                                                                                                                                   Yes                                                                                                                   Session                                                    Yes
sql_log_bin                                                                                                                                         Yes                                                                                                                   Session                                                    Yes
sql_log_off                                                                                                                                         Yes                                                                                                                   Session                                                    Yes
sql_log_update                                                                                                                                      Yes                                                                                                                   Session                                                    Yes
sql_low_priority_updates                                                                                                                            Yes                                                                                                                   Both                                                       Yes
sql_max_join_size                                                                                                                                   Yes                                                                                                                   Both                                                       Yes
sql-mode                      Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: sql_mode                                                                                                                              Yes                                                                                                                   Both                                                       Yes
sql_notes                                                                                                                                           Yes                                                                                                                   Session                                                    Yes
sql_quote_show_create                                                                                                                               Yes                                                                                                                   Session                                                    Yes
sql_safe_updates                                                                                                                                    Yes                                                                                                                   Session                                                    Yes
sql_select_limit                                                                                                                                    Yes                                                                                                                   Both                                                       Yes
sql_slave_skip_counter                                                                                                                              Yes                                                                                                                   Global                                                     Yes
sql_warnings                                                                                                                                        Yes                                                                                                                   Session                                                    Yes
ssl                           Yes                                                        Yes                                                                                                                                                                                                                                         
Ssl_accept_renegotiates                                                                                                                                                                                        Yes                                                        Global                                                     No
Ssl_accepts                                                                                                                                                                                                    Yes                                                        Global                                                     No
ssl-ca                        Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_ca                                                                                                                                Yes                                                                                                                   Global                                                     No
Ssl_callback_cache_hits                                                                                                                                                                                        Yes                                                        Global                                                     No
ssl-capath                    Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_capath                                                                                                                            Yes                                                                                                                   Global                                                     No
ssl-cert                      Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_cert                                                                                                                              Yes                                                                                                                   Global                                                     No
ssl-cipher                    Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_cipher                                                                                                                            Yes                                                                                                                   Global                                                     No
Ssl_cipher                                                                                                                                                                                                     Yes                                                        Both                                                       No
Ssl_cipher_list                                                                                                                                                                                                Yes                                                        Both                                                       No
Ssl_client_connects                                                                                                                                                                                            Yes                                                        Global                                                     No
Ssl_connect_renegotiates                                                                                                                                                                                       Yes                                                        Global                                                     No
Ssl_ctx_verify_depth                                                                                                                                                                                           Yes                                                        Global                                                     No
Ssl_ctx_verify_mode                                                                                                                                                                                            Yes                                                        Global                                                     No
Ssl_default_timeout                                                                                                                                                                                            Yes                                                        Both                                                       No
Ssl_finished_accepts                                                                                                                                                                                           Yes                                                        Global                                                     No
Ssl_finished_connects                                                                                                                                                                                          Yes                                                        Global                                                     No
ssl-key                       Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_key                                                                                                                               Yes                                                                                                                   Global                                                     No
Ssl_session_cache_hits                                                                                                                                                                                         Yes                                                        Global                                                     No
Ssl_session_cache_misses                                                                                                                                                                                       Yes                                                        Global                                                     No
Ssl_session_cache_mode                                                                                                                                                                                         Yes                                                        Global                                                     No
Ssl_session_cache_overflows                                                                                                                                                                                    Yes                                                        Global                                                     No
Ssl_session_cache_size                                                                                                                                                                                         Yes                                                        Global                                                     No
Ssl_session_cache_timeouts                                                                                                                                                                                     Yes                                                        Global                                                     No
Ssl_sessions_reused                                                                                                                                                                                            Yes                                                        Both                                                       No
Ssl_used_session_cache_entries                                                                                                                                                                                 Yes                                                        Global                                                     No
Ssl_verify_depth                                                                                                                                                                                               Yes                                                        Both                                                       No
Ssl_verify_mode                                                                                                                                                                                                Yes                                                        Both                                                       No
ssl-verify-server-cert        Yes                                                        Yes                                                                                                                                                                                                                                         
Ssl_version                                                                                                                                                                                                    Yes                                                        Both                                                       No
standalone                    Yes                                                        Yes                                                                                                                                                                                                                                         
storage_engine                                                                                                                                      Yes                                                                                                                   Both                                                       Yes
symbolic-links                Yes                                                        Yes                                                                                                                                                                                                                                         
sync-binlog                   Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: sync_binlog                                                                                                                           Yes                                                                                                                   Global                                                     Yes
sync-frm                      Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: sync_frm                                                                                                                              Yes                                                                                                                   Global                                                     Yes
sync-master-info              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
sync-relay-log                Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
sync-relay-log-info           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
sysdate-is-now                Yes                                                        Yes                                                                                                                                                                                                                                         
system_time_zone                                                                                                                                    Yes                                                                                                                   Global                                                     No
table_cache                   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
table_definition_cache        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
table_lock_wait_timeout       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Table_locks_immediate                                                                                                                                                                                          Yes                                                        Global                                                     No
Table_locks_waited                                                                                                                                                                                             Yes                                                        Global                                                     No
table_open_cache              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
tc-heuristic-recover          Yes                                                        Yes                                                                                                                                                                                                                                         
Tc_log_max_pages_used                                                                                                                                                                                          Yes                                                        Global                                                     No
Tc_log_page_size                                                                                                                                                                                               Yes                                                        Global                                                     No
Tc_log_page_waits                                                                                                                                                                                              Yes                                                        Global                                                     No
temp-pool                     Yes                                                        Yes                                                                                                                                                                                                                                         
thread_cache_size             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
thread_concurrency            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
thread_handling               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
thread_pool_size              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
thread_stack                  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Threads_cached                                                                                                                                                                                                 Yes                                                        Global                                                     No
Threads_connected                                                                                                                                                                                              Yes                                                        Global                                                     No
Threads_created                                                                                                                                                                                                Yes                                                        Global                                                     No
Threads_running                                                                                                                                                                                                Yes                                                        Global                                                     No
time_format                   Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
time_zone                     Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
timed_mutexes                 Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
timestamp                                                                                                                                           Yes                                                                                                                   Session                                                    Yes
tmp_table_size                Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
tmpdir                        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
transaction_alloc_block_size  Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
transaction-isolation         Yes                                                        Yes                                                                                                                                                                                                                                         
transaction_prealloc_size     Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
tx_isolation                                                                                                                                        Yes                                                                                                                   Both                                                       Yes
unique_checks                                                                                                                                       Yes                                                                                                                   Session                                                    Yes
updatable_views_with_limit    Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Uptime                                                                                                                                                                                                         Yes                                                        Global                                                     No
Uptime_since_flush_status                                                                                                                                                                                      Yes                                                        Global                                                     No
use-symbolic-links            Yes                                                        Yes                                                                                                                                                                                                                                         
user                          Yes                                                        Yes                                                                                                                                                                                                                                         
verbose                       Yes                                                        Yes                                                                                                                                                                                                                                         
version                       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
version_comment                                                                                                                                     Yes                                                                                                                   Global                                                     No
version_compile_machine                                                                                                                             Yes                                                                                                                   Global                                                     No
version_compile_os                                                                                                                                  Yes                                                                                                                   Global                                                     No
wait_timeout                  Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
warning_count                                                                                                                                       Yes                                                                                                                   Session                                                    No


File: manual.info,  Node: server-options,  Next: server-system-variables,  Prev: mysqld-option-tables,  Up: mysqld-server

5.1.2 Server Command Options
----------------------------

When you start the *Note `mysqld': mysqld. server, you can specify
program options using any of the methods described in *Note
program-options::. The most common methods are to provide options in an
option file or on the command line. However, in most cases it is
desirable to make sure that the server uses the same options each time
it runs. The best way to ensure this is to list them in an option file.
See *Note option-files::.

MySQL Enterprise

For expert advice on setting command options, subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Note `mysqld': mysqld. reads options from the `[mysqld]' and `[server]'
groups. *Note `mysqld_safe': mysqld-safe. reads options from the
`[mysqld]', `[server]', `[mysqld_safe]', and `[safe_mysqld]' groups.
*Note `mysql.server': mysql-server. reads options from the `[mysqld]'
and `[mysql.server]' groups.

An embedded MySQL server usually reads options from the `[server]',
`[embedded]', and `[XXXXX_SERVER]' groups, where XXXXX is the name of
the application into which the server is embedded.

*Note `mysqld': mysqld. accepts many command options. For a brief
summary, execute *Note `mysqld --help': mysqld. To see the full list,
use *Note `mysqld --verbose --help': mysqld.

The following list shows some of the most common server options.
Additional options are described in other sections:

   * Options that affect security: See *Note privileges-options::.

   * SSL-related options: See *Note ssl-options::.

   * Binary log control options: See *Note binary-log::.

   * Replication-related options: See *Note replication-options::.

   * Options specific to particular storage engines: See *Note
     myisam-start::, and *Note innodb-parameters::.

You can also set the values of server system variables by using
variable names as options, as described at the end of this section.

   *  `--help', `-?'

     *Command Line        `-?'
     Format*              
     *Config File Format* `help'

     Display a short help message and exit. Use both the `--verbose' and
     `--help' options to see the full message.

   *  `--allow-suspicious-udfs'

     *Command Line        `--allow-suspicious-udfs'
     Format*              
     *Config File Format* `allow-suspicious-udfs'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     This option controls whether user-defined functions that have only
     an `xxx' symbol for the main function can be loaded. By default,
     the option is off and only UDFs that have at least one auxiliary
     symbol can be loaded; this prevents attempts at loading functions
     from shared object files other than those containing legitimate
     UDFs. See *Note udf-security::.

   *  `--ansi'

     *Command Line        `--ansi'
     Format*              
     *Config File Format* `ansi'

     Use standard (ANSI) SQL syntax instead of MySQL syntax. For more
     precise control over the server SQL mode, use the `--sql-mode'
     option instead. See *Note ansi-mode::, and *Note server-sql-mode::.

   *  `--basedir=PATH', `-b PATH'

     *Command Line        `--basedir=name'
     Format*              
     *Config File Format* `basedir'
     *Option Sets         Yes, `basedir'
     Variable*            
     *Variable Name*      `basedir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path to the MySQL installation directory. All paths are
     usually resolved relative to this directory.

   *  `--big-tables'

     *Command Line        `--big-tables'
     Format*              
     *Config File Format* `big-tables'
     *Option Sets         Yes, `big_tables'
     Variable*            
     *Variable Name*      `big-tables'
     *Variable Scope*     Session
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          

     Allow large result sets by saving all temporary sets in files.
     This option prevents most `table full' errors, but also slows down
     queries for which in-memory tables would suffice. Since MySQL
     3.23.2, the server is able to handle large result sets
     automatically by using memory for small temporary tables and
     switching to disk tables where necessary.

   *  `--bind-address=IP'

     *Command Line        `--bind-address=name'
     Format*              
     *Config File Format* `bind-address'
     *Value Set *         
     Typestring           
     Default0.0.0.0       
     Range0.0.0.0-255.255.255.255

     The IP address to bind to. Only one address can be selected.  If
     this option is specified multiple times, the last address given is
     used.

     If no address or `0.0.0.0' is specified, the server listens on all
     interfaces.

   *  `--binlog-format={ROW|STATEMENT|MIXED}'

     *Command Line        `--binlog-format'
     Format*              
     *Config File Format* `binlog-format'
     *Option Sets         Yes, `binlog_format'
     Variable*            
     *Variable Name*      `binlog_format'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultSTATEMENT     
     Valid ValuesROW,     
     STATEMENT, MIXED     

     Specify whether to use row-based, statement-based, or mixed
     replication (mixed is the default in MySQL 6.0).  See *Note
     replication-formats::.

   *  `--bootstrap'

     *Command Line        `--bootstrap'
     Format*              
     *Config File Format* `bootstrap'

     This option is used by the *Note `mysql_install_db':
     mysql-install-db.  script to create the MySQL privilege tables
     without having to start a full MySQL server.

     This option is unavailable if MySQL was configured with the
     `--disable-grant-options' option. See *Note configure-options::.

   *  `--character-sets-dir=PATH'

     *Command Line        `--character-sets-dir=name'
     Format*              
     *Config File Format* `character-sets-dir'
     *Option Sets         Yes, `character_sets_dir'
     Variable*            
     *Variable Name*      `character-sets-dir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--character-set-client-handshake'

     *Command Line        `--character-set-client-handshake'
     Format*              
     *Config File Format* `character-set-client-handshake'
     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     Don't ignore character set information sent by the client. To
     ignore client information and use the default server character
     set, use `--skip-character-set-client-handshake'; this makes MySQL
     behave like MySQL 4.0.

   *  `--character-set-filesystem=CHARSET_NAME'

     *Command Line        `--character-set-filesystem=name'
     Format*              
     *Config File Format* `character-set-filesystem'
     *Option Sets         Yes, `character_set_filesystem'
     Variable*            
     *Variable Name*      `character_set_filesystem'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The file system character set. This option sets the
     `character_set_filesystem' system variable.

   *  `--character-set-server=CHARSET_NAME', `-C CHARSET_NAME'

     *Command Line        `--character-set-server'
     Format*              
     *Config File Format* `character-set-server'
     *Option Sets         Yes, `character_set_server'
     Variable*            
     *Variable Name*      `character_set_server'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     Use CHARSET_NAME as the default server character set. See *Note
     charset-configuration::. If you use this option to specify a
     non-default character set, you should also use
     `--collation-server' to specify the collation.

   *  `--chroot=PATH', `-r PATH'

     *Command Line        `--chroot=name'
     Format*              
     *Config File Format* `chroot'
     *Value Set *         
     Typefilename         

     Put the *Note `mysqld': mysqld. server in a closed environment
     during startup by using the `chroot()' system call. This is a
     recommended security measure. Note that use of this option
     somewhat limits *Note `LOAD DATA INFILE': load-data. and *Note
     `SELECT ... INTO OUTFILE': select.

   *  `--collation-server=COLLATION_NAME'

     *Command Line        `--collation-server'
     Format*              
     *Config File Format* `collation-server'
     *Option Sets         Yes, `collation_server'
     Variable*            
     *Variable Name*      `collation_server'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     Use COLLATION_NAME as the default server collation. See *Note
     charset-configuration::.

   *  `--console'

     *Command Line        `--console'
     Format*              
     *Config File Format* `console'
     *Option Sets         Yes, `console'
     Variable*            
     *Platform Specific*  windows

     (Windows only.) Write error log messages to `stderr' and `stdout'
     even if `--log-error' is specified.  *Note `mysqld': mysqld. does
     not close the console window if this option is used.

   *  `--core-file'

     *Command Line        `--core-file'
     Format*              
     *Config File Format* `core-file'
     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     Write a core file if *Note `mysqld': mysqld. dies. The name and
     location of the core file is system dependent. On Linux, a core
     file named `core.PID' is written to the current working directory
     of the process, which for *Note `mysqld': mysqld. is the data
     directory.  PID represents the process ID of the server process.
     On Mac OS X, a core file named `core.PID' is written to the
     `/cores' directory. On Solaris, use the `coreadm' command to
     specify where to write the core file and how to name it.

     For some systems, to get a core file you must also specify the
     `--core-file-size' option to *Note `mysqld_safe': mysqld-safe. See
     *Note mysqld-safe::. On some systems, such as Solaris, you do not
     get a core file if you are also using the `--user' option. There
     might be additional restrictions or limitations. For example, it
     might be necessary to execute `ulimit -c unlimited' before
     starting the server. Consult your system documentation.

   *  `--datadir=PATH', `-h PATH'

     *Command Line        `--datadir=name'
     Format*              
     *Config File Format* `datadir'
     *Option Sets         Yes, `datadir'
     Variable*            
     *Variable Name*      `datadir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path to the data directory.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     *Command Line        `--debug[=debug_options]'
     Format*              
     *Config File Format* `debug'
     *Variable Name*      `debug'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           
     Default'd:t:o,/tmp/mysqld.trace

     If MySQL is configured with `--with-debug', you can use this
     option to get a trace file of what *Note `mysqld': mysqld. is
     doing. A typical DEBUG_OPTIONS string is `'d:t:o,FILE_NAME''.  The
     default is `'d:t:i:o,mysqld.trace''. See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

     Using `--with-debug' to configure MySQL with debugging support
     enables you to use the `--debug="d,parser_debug"' option when you
     start the server. This causes the Bison parser that is used to
     process SQL statements to dump a parser trace to the server's
     standard error output. Typically, this output is written to the
     error log.

     This option may be given multiple times. Values that begin with
     `+' or `-' are added to or subtracted from the previous value. For
     example, `--debug=T' `--debug=+P' sets the value to `P:T'.

   *  `--debug-sync-timeout[=N]'

     *Version Introduced* 6.0.6
     *Command Line        `--debug-sync-timeout[=#]'
     Format*              
     *Config File Format* `debug-sync-timeout'
     *Value Set *         
     Typenumeric          

     Controls whether the Debug Sync facility for testing and debugging
     is enabled. Use of Debug Sync requires that MySQL be configured
     with the `--enable-debug-sync' option (see *Note
     configure-options::). If Debug Sync is not compiled in, this
     option is not available. The option value is a timeout in seconds.
     The default value is 0, which disables Debug Sync. To enable it,
     specify a value greater than 0; this value also becomes the
     default timeout for individual synchronization points. If the
     option is given without a value, the timeout is set to 300 seconds.

     For a description of the Debug Sync facility and how to use
     synchronization points, see MySQL Internals: Test Synchronization
     (http://forge.mysql.com/wiki/MySQL_Internals_Test_Synchronization).

     This option was added in MySQL 6.0.6.

   *  `--default-character-set=CHARSET_NAME' (_DEPRECATED_)

     *Command Line        `--default-character-set=name'
     Format*              
     *Config File Format* `default-character-set'
     *Deprecated*         5.0
     *Value Set *         
     Typestring           

     Use CHARSET_NAME as the default character set. This option is
     deprecated in favor of `--character-set-server'. See *Note
     charset-configuration::.

   *  `--default-collation=COLLATION_NAME'

     *Command Line        `--default-collation=name'
     Format*              
     *Variable Name*      `default-collation'
     *Variable Scope*     
     *Dynamic Variable*   No
     *Deprecated*         4.1.3
     *Value Set *         
     Typestring           

     Use COLLATION_NAME as the default collation. This option is
     deprecated in favor of `--collation-server'. See *Note
     charset-configuration::.

   *  `--default-storage-engine=TYPE'

     *Command Line        `--default-storage-engine=name'
     Format*              
     *Config File Format* `default-storage-engine'

     Set the default storage engine (table type) for tables. See *Note
     storage-engines::.

   *  `--default-table-type=TYPE'

     *Version Removed*    6.0.8
     *Command Line        `--default-table-type=name'
     Format*              
     *Config File Format* `default-table-type'
     *Deprecated*         5.0, by `default-storage-engine'
     *Value Set *         
     Typestring           

     This option is a deprecated synonym for
     `--default-storage-engine'. It has been removed as of MySQL 6.0.8.

   *  `--default-time-zone=TIMEZONE'

     *Command Line        `--default-time-zone=name'
     Format*              
     *Config File Format* `default-time-zone'
     *Value Set *         
     Typestring           

     Set the default server time zone. This option sets the global
     `time_zone' system variable. If this option is not given, the
     default time zone is the same as the system time zone (given by
     the value of the `system_time_zone' system variable.

   *  `--delay-key-write[={OFF|ON|ALL}]'

     *Command Line        `--delay-key-write[=name]'
     Format*              
     *Config File Format* `delay-key-write'
     *Option Sets         Yes, `delay_key_write'
     Variable*            
     *Variable Name*      `delay-key-write'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultON Valid      
     ValuesON, OFF, ALL   

     Specify how to use delayed key writes. Delayed key writing causes
     key buffers not to be flushed between writes for `MyISAM' tables.
     `OFF' disables delayed key writes. `ON' enables delayed key writes
     for those tables that were created with the `DELAY_KEY_WRITE'
     option.  `ALL' delays key writes for all `MyISAM' tables. See
     *Note server-parameters::, and *Note myisam-start::.

     *Note*:

     If you set this variable to `ALL', you should not use `MyISAM'
     tables from within another program (such as another MySQL server or
     *Note `myisamchk': myisamchk.) when the tables are in use.  Doing
     so leads to index corruption.

   *  `--des-key-file=FILE_NAME'

     *Command Line        `--des-key-file=name'
     Format*              
     *Config File Format* `des-key-file'

     Read the default DES keys from this file. These keys are used by
     the `DES_ENCRYPT()' and `DES_DECRYPT()' functions.

   *  `--enable-named-pipe'

     Enable support for named pipes. This option applies only on
     Windows NT, 2000, XP, and 2003 systems.

   *  `--enable-pstack'

     *Command Line        `--enable-pstack'
     Format*              
     *Config File Format* `enable-pstack'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Print a symbolic stack trace on failure.

   *  `--engine-condition-pushdown={ON|OFF}'

     *Command Line        `--engine-condition-pushdown'
     Format*              
     *Config File Format* `engine-condition-pushdown'
     *Option Sets         Yes, `engine_condition_pushdown'
     Variable*            
     *Variable Name*      `engine_condition_pushdown'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultON            

     When the value of this option is 0 (`OFF'), a query such as
     `SELECT * FROM t WHERE mycol = 42', where `mycol' is a non-indexed
     column, is executed as a full table scan. The storage engine sends
     every row to the MySQL server, which applies the `WHERE'
     condition. If `engine_condition_pushdown' is set to 1 (`ON'), the
     condition is `pushed down' to the storage engine, which uses the
     condition to perform the scan, and sends back to the MySQL server
     only those rows that match the condition. By default, this variable
     is `OFF'.

     In MySQL 6.0, this option can be used only with the `MyISAM'
     storage engine. It may be implemented for additional storage
     engines in future MySQL releases.

     For more information, see *Note condition-pushdown-optimization::.

   *  `--event-scheduler[=VALUE]'

     *Command Line        `--event-scheduler[=value]'
     Format*              
     *Config File Format* `event-scheduler'
     *Option Sets         Yes, `event_scheduler'
     Variable*            
     *Variable Name*      `event_scheduler'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultOFF Valid     
     ValuesON, OFF,       
     DISABLED             

     Enable or disable, and start or stop, the event scheduler.

     For detailed information, see The `event-scheduler' Option.

   *  `--exit-info[=FLAGS]', `-T [FLAGS]'

     *Command Line        `--exit-info[=flags]'
     Format*              
     *Config File Format* `exit-info'
     *Value Set *         
     Typenumeric          

     This is a bit mask of different flags that you can use for
     debugging the *Note `mysqld': mysqld. server. Do not use this
     option unless you know _exactly_ what it does!

   *  `--external-locking'

     *Command Line        `--external-locking'
     Format*              
     *Config File Format* `external-locking'
     *Option Sets         Yes, `external_locking'
     Variable*            
     *Disabled by*        `skip-external-locking'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Enable external locking (system locking), which is disabled by
     default as of MySQL 4.0. Note that if you use this option on a
     system on which `lockd' does not fully work (such as Linux), it is
     easy for *Note `mysqld': mysqld. to deadlock. This option
     previously was named `--enable-locking'.

     For more information about external locking, including conditions
     under which it can and cannot be used, see *Note
     external-locking::.

   *  `--flush'

     *Command Line        `--flush'
     Format*              
     *Config File Format* `flush'
     *Variable Name*      `flush'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Flush (synchronize) all changes to disk after each SQL statement.
     Normally, MySQL does a write of all changes to disk only after
     each SQL statement and lets the operating system handle the
     synchronizing to disk. See *Note crashing::.

   *  `--gdb'

     *Command Line        `--gdb'
     Format*              
     *Config File Format* `gdb'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Install an interrupt handler for `SIGINT' (needed to stop *Note
     `mysqld': mysqld. with `^C' to set breakpoints) and disable stack
     tracing and core file handling. See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   *  `--general-log[={0|1}]'

     *Command Line        `--general-log'
     Format*              
     *Config File Format* `general-log'
     *Option Sets         Yes, `general_log'
     Variable*            
     *Variable Name*      `general_log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Specify the initial general query log state. With no argument or
     an argument of 1, the `--general-log' option enables the log. If
     omitted or given with an argument of 0, the option disables the
     log.

   *  `--init-file=FILE_NAME'

     *Command Line        `--init-file=name'
     Format*              
     *Config File Format* `init-file'
     *Option Sets         Yes, `init_file'
     Variable*            
     *Variable Name*      `init_file'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     Read SQL statements from this file at startup. Each statement must
     be on a single line and should not include comments.

     This option is unavailable if MySQL was configured with the
     `--disable-grant-options' option. See *Note configure-options::.

   * `--innodb-XXX'

     The `InnoDB' options are listed in *Note innodb-parameters::.

   *  `--language=LANG_NAME, -L LANG_NAME'

     *Command Line        `--language=name'
     Format*              
     *Config File Format* `language'
     *Option Sets         Yes, `language'
     Variable*            
     *Variable Name*      `language'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     Default/usr/local/mysql/share/mysql/english/

     Return client error messages in the given language.  LANG_NAME can
     be given as the language name or as the full path name to the
     directory where the language files are installed. See *Note
     error-message-language::.

   *  `--large-pages'

     *Command Line        `--large-pages'
     Format*              
     *Config File Format* `large-pages'
     *Option Sets         Yes, `large_pages'
     Variable*            
     *Variable Name*      `large_pages'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Platform Specific*  linux
     *Value Set *         
     Type (linux)boolean  
     DefaultFALSE         

     Some hardware/operating system architectures support memory pages
     greater than the default (usually 4KB). The actual implementation
     of this support depends on the underlying hardware and operating
     system. Applications that perform a lot of memory accesses may
     obtain performance improvements by using large pages due to
     reduced Translation Lookaside Buffer (TLB) misses.

     Currently, MySQL supports only the Linux implementation of large
     page support (which is called HugeTLB in Linux). See *Note
     large-page-support::.

     This option is disabled by default.

   *  `--log[=FILE_NAME]', `-l [FILE_NAME]'

     *Command Line        `--log[=name]'
     Format*              
     *Config File Format* `log'
     *Option Sets         Yes, `log'
     Variable*            
     *Variable Name*      `log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Deprecated*         5.1.29, by `general-log'
     *Value Set *         
     Typestring           
     DefaultOFF           

     This option enables logging to the general query log, which
     contains entries that record client connections and SQL statements
     received from clients. The log output destination can be selected
     with the `--log-output' option. See *Note log-tables::, and *Note
     query-log::.

     As of MySQL 6.0.8, the `--log' option is deprecated and will be
     removed (along with the `log' system variable) in MySQL 7.0.
     Instead, use the `--general_log' option to enable the general
     query log and the `--general_log_file=FILE_NAME' option to set the
     general query log file name.

   *  `--log-backup-output[=VALUE,...]'

     *Version Introduced* 6.0.8
     *Command Line        `--log-backup-output[=name]'
     Format*              
     *Config File Format* `log-backup-output'
     *Option Sets         Yes, `log_backup_output'
     Variable*            
     *Variable Name*      `log_backup_output'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultTABLE Valid   
     ValuesTABLE, FILE,   
     NONE                 

     This option determines the destination for MySQL Backup history
     and progress log output. The option value can be given as one or
     more of the words `TABLE', `FILE', or `NONE'. If the option is
     given without a value, the default is `TABLE'. `TABLE' selects
     logging to the `backup_history' and `backup_progress' log tables
     in the `mysql' database as a destination.  `FILE' selects logging
     to log files as a destination. `NONE' disables logging. If `NONE'
     is present in the option value, it takes precedence over any other
     words that are present.  `TABLE' and `FILE' can both be given to
     select to both log output destinations.

     This option selects log output destinations, but does not enable
     log output. To do that, use the `--backup_history_log' and
     `--backup_progress_log' options.  For `FILE' logging, the default
     log files are `backup_history.log' and `backup_progress.log' in
     the data directory.  To change the names, set the global
     `backup_history_log_file' and `backup_progress_log_file' system
     variables. For more information, see *Note
     backup-database-restore-log-control::.

     This option was added in MySQL 6.0.8.

   *  `--log-error[=FILE_NAME]'

     *Command Line        `--log-error[=name]'
     Format*              
     *Config File Format* `log-error'
     *Option Sets         Yes, `log_error'
     Variable*            
     *Variable Name*      `log_error'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     Log errors and startup messages to this file. See *Note
     error-log::. If you omit the file name, MySQL uses `HOST_NAME.err'.
     If the file name has no extension, the server adds an extension of
     `.err'.

   *  `--log-isam[=FILE_NAME]'

     *Command Line        `--log-isam[=name]'
     Format*              
     *Config File Format* `log-isam'
     *Value Set *         
     Typefilename         

     Log all `MyISAM' changes to this file (used only when debugging
     `MyISAM').

   *  `--log-long-format' (_DEPRECATED_)

     *Command Line        `--log-long-format'
     Format*              
     *Config File Format* `log-long-format'
     *Deprecated*         4.1

     Log extra information to the binary log and slow query log, if
     they have been activated. For example, the user name and timestamp
     are logged for all queries. This option is deprecated, as it now
     represents the default logging behavior.  (See the description for
     `--log-short-format'.) The `--log-queries-not-using-indexes'
     option is available for the purpose of logging queries that do not
     use indexes to the slow query log.

   *  `--log-output[=VALUE,...]'

     *Command Line        `--log-output[=name]'
     Format*              
     *Config File Format* `log-output'
     *Option Sets         Yes, `log_output'
     Variable*            
     *Variable Name*      `log_output'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultFILE Valid    
     ValuesTABLE, FILE,   
     NONE                 

     This option determines the destination for general query log and
     slow query log output. The option value can be given as one or
     more of the words `TABLE', `FILE', or `NONE'. If the option is
     given without a value, the default is `FILE'. `TABLE' selects
     logging to the `general_log' and `slow_log' tables in the `mysql'
     database as a destination.  `FILE' selects logging to log files as
     a destination. `NONE' disables logging. If `NONE' is present in
     the option value, it takes precedence over any other words that
     are present.  `TABLE' and `FILE' can both be given to select to
     both log output destinations.

     This option selects log output destinations, but does not enable
     log output. To do that, use the `--general_log' and
     `--slow_query_log' options. For `FILE' logging, the
     `--general_log_file' and `-slow_query_log_file' options determine
     the log file location. (Before MySQL 6.0.8, enable the logs with
     the `--log' and `--log-slow-queries' options. The options take an
     optional file name argument to specify the log file name.) For
     more information, see *Note log-tables::.

   *  `--log-queries-not-using-indexes'

     *Command Line        `--log-queries-not-using-indexes'
     Format*              
     *Config File Format* `log-queries-not-using-indexes'
     *Option Sets         Yes, `log_queries_not_using_indexes'
     Variable*            
     *Variable Name*      `log_queries_not_using_indexes'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Deprecated*         5.1.29, by `slow-query-log'
     *Value Set *         
     Typeboolean          

     If you are using this option with the slow query log enabled,
     queries that are expected to retrieve all rows are logged. See
     *Note slow-query-log::. This option does not necessarily mean that
     no index is used. For example, a query that uses a full index scan
     uses an index but would be logged because the index would not
     limit the number of rows.

   *  `--log-short-format'

     *Command Line        `--log-short-format'
     Format*              
     *Config File Format* `log-short-format'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Originally intended to log less information to the binary log and
     slow query log, if they have been activated. However, this option
     is not operational.

   *  `--log-slow-admin-statements'

     *Command Line        `--log-slow-admin-statements'
     Format*              
     *Config File Format* `log-slow-admin-statements'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Log slow administrative statements such as *Note `OPTIMIZE TABLE':
     optimize-table, *Note `ANALYZE TABLE': analyze-table, and *Note
     `ALTER TABLE': alter-table. to the slow query log.

   *  `--log-slow-queries[=FILE_NAME]'

     *Command Line        `--log-slow-queries[=name]'
     Format*              
     *Config File Format* `log-slow-queries'
     *Option Sets         Yes, `log_slow_queries'
     Variable*            
     *Variable Name*      `log_slow_queries'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          

     This option enables logging to the slow query log, which contains
     entries for all queries that have taken more than
     `long_query_time' seconds to execute. See the descriptions of the
     `--log-long-format' and `--log-short-format' options for details.

     The log output destination can be selected with the `--log-output'
     option. If you omit the file name, MySQL uses `HOST_NAME-slow.log'
     as the file name. See *Note log-tables::, and *Note
     slow-query-log::.

     As of MySQL 6.0.8, the `--log-slow-queries' option is deprecated
     and will be removed (along with the `log_slow_queries' system
     variable) in MySQL 7.0. Instead, use the `--slow_query_log' option
     to enable the slow query log and the
     `--slow_query_log_file=FILE_NAME' option to set the slow query log
     file name.

   *  `--log-tc=FILE_NAME'

     *Command Line        `--log-tc=name'
     Format*              
     *Config File Format* `log-tc'
     *Value Set *         
     Typefilename         
     Defaulttc.log        

     The name of the memory-mapped transaction coordinator log file
     (for XA transactions that affect multiple storage engines when the
     binary log is disabled). The default name is `tc.log'. The file is
     created under the data directory if not given as a full path name.
     Currently, this option is unused.

   *  `--log-tc-size=SIZE'

     *Command Line        `--log-tc-size=#'
     Format*              
     *Config File Format* `log-tc-size'
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default24576 Max     
     Value4294967295      
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default24576 Max     
     Value18446744073709547520

     The size in bytes of the memory-mapped transaction coordinator
     log. The default size is 24KB.

   *  `--log-warnings[=LEVEL]', `-W [LEVEL]'

     *Command Line        `--log-warnings[=#]'
     Format*              
     *Config File Format* `log-warnings'
     *Option Sets         Yes, `log_warnings'
     Variable*            
     *Variable Name*      `log_warnings'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Disabled by*        `skip-log-warnings'
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default1             
     Range0-18446744073709547520

     Print out warnings such as `Aborted connection...' to the error
     log. Enabling this option is recommended, for example, if you use
     replication (you get more information about what is happening,
     such as messages about network failures and reconnections). This
     option is enabled (1) by default, and the default LEVEL value if
     omitted is 1. To disable this option, use `--log-warnings=0'. If
     the value is greater than 1, aborted connections are written to the
     error log, and access-denied errors for new connection attempts
     are written. See *Note communication-errors::.

     If a slave server was started with `--log-warnings' enabled, the
     slave prints messages to the error log to provide information
     about its status, such as the binary log and relay log coordinates
     where it starts its job, when it is switching to another relay
     log, when it reconnects after a disconnect, and so forth.

   *  `--low-priority-updates'

     *Command Line        `--low-priority-updates'
     Format*              
     *Config File Format* `low-priority-updates'
     *Option Sets         Yes, `low_priority_updates'
     Variable*            
     *Variable Name*      `low_priority_updates'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Give table-modifying operations (*Note `INSERT': insert, *Note
     `REPLACE': replace, *Note `DELETE': delete, *Note `UPDATE':
     update.) lower priority than selects. This can also be done via
     `{INSERT | REPLACE | DELETE | UPDATE} LOW_PRIORITY ...' to lower
     the priority of only one query, or by `SET LOW_PRIORITY_UPDATES=1'
     to change the priority in one thread. This affects only storage
     engines that use only table-level locking (`MyISAM', `MEMORY',
     `MERGE'). See *Note table-locking::.

   *  `--min-examined-row-limit=NUMBER'

     *Version Introduced* 6.0.4
     *Command Line        `--min-examined-row-limit=#'
     Format*              
     *Config File Format* `min-examined-row-limit'
     *Variable Name*      `min_examined_row_limit'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default0             
     Range0-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default0             
     Range0-18446744073709547520

     When this option is set, queries which examine fewer than NUMBER
     rows are not written to the slow query log. The default is 0.

     This option was introduced in MySQL 6.0.4.

   *  `--memlock'

     *Command Line        `--memlock'
     Format*              
     *Config File Format* `memlock'
     *Variable Name*      `locked_in_memory'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Lock the *Note `mysqld': mysqld. process in memory. This option
     might help if you have a problem where the operating system is
     causing *Note `mysqld': mysqld. to swap to disk.

     `--memlock' works on systems that support the `mlockall()' system
     call; this includes Solaris as well as most Linux distributions
     that use a 2.4 or newer kernel. On Linux systems, you can tell
     whether or not `mlockall()' (and thus this option) is supported by
     checking to see whether or not it is defined in the system
     `mman.h' file, like this:

          shell> grep mlockall /usr/include/sys/mman.h

     If `mlockall()' is supported, you should see in the output of the
     previous command something like the following:

          extern int mlockall (int __flags) __THROW;

     *Important*:

     Using this option requires that you run the server as `root',
     which, for reasons of security, is normally not a good idea. See
     *Note changing-mysql-user::.

     You must not try to use this option on a system that does not
     support the `mlockall()' system call; if you do so, *Note
     `mysqld': mysqld. will very likely crash as soon as you try to
     start it.

   *  `--myisam-block-size=N'

     *Command Line        `--myisam-block-size=#'
     Format*              
     *Config File Format* `myisam-block-size'
     *Value Set *         
     Typenumeric          
     Default1024          
     Range1024-16384      

     The block size to be used for `MyISAM' index pages.

   *  `--myisam-recover[=OPTION[,OPTION]...]]'

     *Command Line        `--myisam-recover[=name]'
     Format*              
     *Config File Format* `myisam-recover'
     *Value Set *         
     Typeenumeration      
     DefaultOFF Valid     
     ValuesDEFAULT,       
     BACKUP, FORCE, QUICK 

     Set the `MyISAM' storage engine recovery mode. The option value is
     any combination of the values of `DEFAULT', `BACKUP', `FORCE', or
     `QUICK'. If you specify multiple values, separate them by commas.
     Specifying the option with no argument is the same as specifying
     `DEFAULT', and specifying with an explicit value of `""' disables
     recovery (same as not giving the option). If recovery is enabled,
     each time *Note `mysqld': mysqld. opens a `MyISAM' table, it
     checks whether the table is marked as crashed or wasn't closed
     properly. (The last option works only if you are running with
     external locking disabled.) If this is the case, *Note `mysqld':
     mysqld. runs a check on the table. If the table was corrupted,
     *Note `mysqld': mysqld. attempts to repair it.

     The following options affect how the repair works.

     *Option*   *Description*
     `DEFAULT'  Recovery without backup, forcing, or quick
                checking.
     `BACKUP'   If the data file was changed during recovery,
                save a backup of the `TBL_NAME.MYD' file as
                `TBL_NAME-DATETIME.BAK'.
     `FORCE'    Run recovery even if we would lose more than
                one row from the `.MYD' file.
     `QUICK'    Don't check the rows in the table if there
                aren't any delete blocks.

     Before the server automatically repairs a table, it writes a note
     about the repair to the error log. If you want to be able to
     recover from most problems without user intervention, you should
     use the options `BACKUP,FORCE'. This forces a repair of a table
     even if some rows would be deleted, but it keeps the old data file
     as a backup so that you can later examine what happened.

     See *Note myisam-start::.

   *  `--old-passwords'

     *Command Line        `--old_passwords'
     Format*              
     *Config File Format* `old-passwords'
     *Option Sets         Yes, `old_passwords'
     Variable*            
     *Variable Name*      `old_passwords'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Force the server to generate short (pre-4.1) password hashes for
     new passwords. This is useful for compatibility when the server
     must support older client programs. See *Note password-hashing::.

   *  `--old-style-user-limits'

     *Command Line        `--old-style-user-limits'
     Format*              
     *Config File Format* `old-style-user-limits'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Enable old-style user limits. (Before MySQL 5.0.3, account
     resource limits were counted separately for each host from which a
     user connected rather than per account row in the `user' table.)
     See *Note user-resources::.

   *  `--one-thread'

     *Command Line        `--one-thread'
     Format*              
     *Config File Format* `one-thread'

     Only use one thread (for debugging under Linux). This option is
     available only if the server is built with debugging enabled. See
     MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

     This option is deprecated; use `--thread_handling=no-threads'
     instead.

   *  `--open-files-limit=COUNT'

     *Command Line        `--open-files-limit=#'
     Format*              
     *Config File Format* `open-files-limit'
     *Option Sets         Yes, `open_files_limit'
     Variable*            
     *Variable Name*      `open_files_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-65535         

     Changes the number of file descriptors available to *Note
     `mysqld': mysqld. You should try increasing the value of this
     option if *Note `mysqld': mysqld. gives you the error `Too many
     open files'.  *Note `mysqld': mysqld. uses the option value to
     reserve descriptors with `setrlimit()'. If the requested number of
     file descriptors cannot be allocated, *Note `mysqld': mysqld.
     writes a warning to the error log.

     *Note `mysqld': mysqld. may attempt to allocate more than the
     requested number of descriptors (if they are available), using the
     values of `max_connections' and `table_open_cache' to estimate
     whether more descriptors will be needed.

   *  `--pid-file=PATH'

     *Command Line        `--pid-file=name'
     Format*              
     *Config File Format* `pid-file'
     *Option Sets         Yes, `pid_file'
     Variable*            
     *Variable Name*      `pid_file'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path name of the process ID file. This file is used by other
     programs such as *Note `mysqld_safe': mysqld-safe. to determine
     the server's process ID.

   *  `--plugin-load=PLUGIN_LIST'

     *Command Line        `--plugin-load=plugin_list'
     Format*              
     *Config File Format* `plugin-load'
     *Value Set *         
     Typestring           

     Under normal startup, the server determines which plugins to load
     by reading the `mysql.plugins' system table. This option enables
     plugins to be loaded even when `--skip-grant-tables' is given
     (which tells the server not to read system tables). This option
     also enables plugins to be loaded at startup under configurations
     when plugins cannot be loaded at runtime.

     The option value is a colon-separated list of `NAME=PLUGIN_LIBRARY'
     values. Each NAME is the name of the plugin, and PLUGIN_LIBRARY is
     the name of the shared library that contains the plugin code.
     Each library file must be located in the directory named by the
     `plugin_dir' system variable. For example, if plugins named
     `myplug1' and `myplug2' have library files `myplug1.so' and
     `myplug2.so', use this option to load them at startup:

          shell> `mysqld --plugin-load=myplug1=myplug1.so:myplug2=myplug2.so'

     All plugins to load must be named in the same `--plugin-load'
     option. If multiple `--plugin-load' options are given, only the
     last one is used.

     The plugins are loaded for a single invocation of *Note `mysqld':
     mysqld. only. After a restart, the plugins are not loaded unless
     `--plugin-load' is used again.  This is in contrast to *Note
     `INSTALL PLUGIN': install-plugin, which adds an entry to the
     `mysql.plugins' table to cause the plugin to be loaded for every
     normal server startup.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     *Command Line        `--port=#'
     Format*              
     *Config File Format* `port'
     *Option Sets         Yes, `port'
     Variable*            
     *Variable Name*      `port'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default3306          

     The port number to use when listening for TCP/IP connections.  The
     port number must be 1024 or higher unless the server is started by
     the `root' system user.

   *  `--port-open-timeout=NUM'

     *Command Line        `--port-open-timeout=#'
     Format*              
     *Config File Format* `port-open-timeout'
     *Value Set *         
     Typenumeric Default0 

     On some systems, when the server is stopped, the TCP/IP port might
     not become available immediately. If the server is restarted
     quickly afterward, its attempt to reopen the port can fail. This
     option indicates how many seconds the server should wait for the
     TCP/IP port to become free if it cannot be opened. The default is
     not to wait.

   *  `--safe-mode'

     *Command Line        `--safe-mode'
     Format*              
     *Config File Format* `safe-mode'
     *Deprecated*         5.0

     Skip some optimization stages.

   *  `--safe-show-database' (_DEPRECATED_)

     *Command Line        `--safe-show-database'
     Format*              
     *Config File Format* `safe-show-database'
     *Option Sets         Yes, `safe_show_database'
     Variable*            
     *Variable Name*      `safe_show_database'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Deprecated*         4.0.2
     *Value Set *         
     Typeboolean          

     See *Note privileges-provided::.

   *  `--safe-user-create'

     *Command Line        `--safe-user-create'
     Format*              
     *Config File Format* `safe-user-create'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     If this option is enabled, a user cannot create new MySQL users by
     using the *Note `GRANT': grant.  statement unless the user has the
     `INSERT' privilege for the `mysql.user' table or any column in the
     table. If you want a user to have the ability to create new users
     that have those privileges that the user has the right to grant,
     you should grant the user the following privilege:

          GRANT INSERT(user) ON mysql.user TO 'USER_NAME'@'HOST_NAME';

     This ensures that the user cannot change any privilege columns
     directly, but has to use the *Note `GRANT': grant. statement to
     give privileges to other users.

   *  `--secure-auth'

     *Command Line        `--secure-auth'
     Format*              
     *Config File Format* `secure-auth'
     *Option Sets         Yes, `secure_auth'
     Variable*            
     *Variable Name*      `secure_auth'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Disallow authentication by clients that attempt to use accounts
     that have old (pre-4.1) passwords.

   *  `--secure-backup-file-priv=PATH'

     *Command Line        `--secure-backup-file-priv'
     Format*              
     *Config File Format* `secure-backup-file-priv'
     *Option Sets         Yes, `secure_backup_file_priv'
     Variable*            
     *Variable Name*      `secure_backup_file_priv'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     This option limits the effect of the *Note `BACKUP DATABASE':
     backup-database. and *Note `RESTORE': restore. statements to work
     only with files in the specified directory. This option was added
     in MySQL 6.0.11; in older releases, use `--secure-file-priv'
     instead.

   *  `--secure-file-priv=PATH'

     *Command Line        `--secure-file-priv'
     Format*              
     *Config File Format* `secure-file-priv'
     *Option Sets         Yes, `secure_file_priv'
     Variable*            
     *Variable Name*      `secure_file_priv'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     This option limits the effect of the `LOAD_FILE()' function and the
     *Note `LOAD DATA': load-data. and *Note `SELECT ... INTO OUTFILE':
     select. statements to work only with files in the specified
     directory. Before MySQL 6.0.11, it also applies to the *Note
     `BACKUP DATABASE': backup-database. and *Note `RESTORE': restore.
     statements; as of 6.0.11, `--secure-backup-file-priv' applies to
     those statements.

   *  `--shared-memory'

     Enable shared-memory connections by local clients. This option is
     available only on Windows.

   *  `--shared-memory-base-name=NAME'

     The name of shared memory to use for shared-memory connections.
     This option is available only on Windows. The default name is
     `MYSQL'. The name is case sensitive.

   *  `--skip-concurrent-insert'

     Turn off the ability to select and insert at the same time on
     `MyISAM' tables. (This is to be used only if you think you have
     found a bug in this feature.) See *Note concurrent-inserts::.

   *  `--skip-external-locking'

     Do not use external locking (system locking). For more information
     about external locking, including conditions under which it can
     and cannot be used, see *Note external-locking::.

     External locking has been disabled by default since MySQL 4.0.

   *  `--skip-grant-tables'

     This option causes the server to start without using the privilege
     system at all, which gives anyone with access to the server
     _unrestricted access to all databases_. You can cause a running
     server to start using the grant tables again by executing *Note
     `mysqladmin flush-privileges': mysqladmin. or *Note `mysqladmin
     reload': mysqladmin. command from a system shell, or by issuing a
     MySQL *Note `FLUSH PRIVILEGES': flush. statement after connecting
     to the server.  This option also suppresses loading of plugins,
     user-defined functions (UDFs), and scheduled events. To cause
     plugins to be loaded anyway, use the `--plugin-load' option.

     `--skip-grant-tables' is unavailable if MySQL was configured with
     the `--disable-grant-options' option. See *Note
     configure-options::.

   *  `--skip-host-cache'

     Do not use the internal host name cache for faster name-to-IP
     resolution. Instead, query the DNS server every time a client
     connects. See *Note dns::.

   *  `--skip-innodb'

     Disable the `InnoDB' storage engine. This saves memory and disk
     space and might speed up some operations. Do not use this option
     if you require `InnoDB' tables.

   *  `--skip-name-resolve'

     Do not resolve host names when checking client connections.  Use
     only IP numbers. If you use this option, all `Host' column values
     in the grant tables must be IP numbers or `localhost'. See *Note
     dns::.

   *  `--skip-networking'

     Don't listen for TCP/IP connections at all. All interaction with
     *Note `mysqld': mysqld. must be made via named pipes or shared
     memory (on Windows) or Unix socket files (on Unix).  This option
     is highly recommended for systems where only local clients are
     allowed. See *Note dns::.

   * `--ssl*'

     Options that begin with `--ssl' specify whether to allow clients
     to connect via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--standalone'

     *Command Line        `--standalone'
     Format*              
     *Config File Format* `standalone'
     *Platform Specific*  windows

     Available on Windows NT-based systems only; instructs the MySQL
     server not to run as a service.

   *  `--symbolic-links', `--skip-symbolic-links'

     *Command Line        `--symbolic-links'
     Format*              
     *Config File Format* `symbolic-links'

     Enable or disable symbolic link support. This option has different
     effects on Windows and Unix:

        * On Windows, enabling symbolic links allows you to establish a
          symbolic link to a database directory by creating a
          `DB_NAME.sym' file that contains the path to the real
          directory. See *Note windows-symbolic-links::.

        * On Unix, enabling symbolic links means that you can link a
          `MyISAM' index file or data file to another directory with
          the `INDEX DIRECTORY' or `DATA DIRECTORY' options of the
          *Note `CREATE TABLE': create-table.  statement. If you delete
          or rename the table, the files that its symbolic links point
          to also are deleted or renamed. See *Note
          symbolic-links-to-tables::.

   *  `--skip-safemalloc'

     *Command Line        `--skip-safe-malloc'
     Format*              
     *Config File Format* `skip-safemalloc'

     If MySQL is configured with `--with-debug=full', all MySQL
     programs check for memory overruns during each memory allocation
     and memory freeing operation. This checking is very slow, so for
     the server you can avoid it when you don't need it by using the
     `--skip-safemalloc' option.

   *  `--skip-show-database'

     *Command Line        `--skip-show-database'
     Format*              
     *Config File Format* `skip-show-database'
     *Option Sets         Yes, `skip_show_database'
     Variable*            
     *Variable Name*      `skip_show_database'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     With this option, the *Note `SHOW DATABASES': show-databases.
     statement is allowed only to users who have the `SHOW DATABASES'
     privilege, and the statement displays all database names.  Without
     this option, *Note `SHOW DATABASES': show-databases. is allowed to
     all users, but displays each database name only if the user has the
     `SHOW DATABASES' privilege or some privilege for the database.
     Note that _any_ global privilege is considered a privilege for the
     database.

   *  `--skip-stack-trace'

     *Command Line        `--skip-stack-trace'
     Format*              
     *Config File Format* `skip-stack-trace'

     Don't write stack traces. This option is useful when you are
     running *Note `mysqld': mysqld. under a debugger. On some systems,
     you also must use this option to get a core file. See MySQL
     Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   *  `--skip-thread-priority'

     *Version Removed*    6.0.8
     *Command Line        `--skip-thread-priority'
     Format*              
     *Config File Format* `skip-thread-priority'
     *Deprecated*         5.1.29

     Disable using thread priorities for faster response time. This
     option was removed in MySQL 6.0.8

   *  `--slow-query-log[={0|1}]'

     *Command Line        `--slow-query-log'
     Format*              
     *Config File Format* `slow-query-log'
     *Option Sets         Yes, `slow_query_log'
     Variable*            
     *Variable Name*      `slow_query_log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Specify the initial slow query log state. With no argument or an
     argument of 1, the `--slow-query-log' option enables the log. If
     omitted or given with an argument of 0, the option disables the
     log.

   *  `--socket=PATH'

     *Command Line        `--socket=name'
     Format*              
     *Config File Format* `socket'
     *Option Sets         Yes, `socket'
     Variable*            
     *Variable Name*      `socket'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     Default/tmp/mysql.sock

     On Unix, this option specifies the Unix socket file to use when
     listening for local connections. The default value is
     `/tmp/mysql.sock'. On Windows, the option specifies the pipe name
     to use when listening for local connections that use a named pipe.
     The default value is `MySQL' (not case sensitive).

   *  `--sql-mode=VALUE[,VALUE[,VALUE...]]'

     *Command Line        `--sql-mode=name'
     Format*              
     *Config File Format* `sql-mode'
     *Option Sets         Yes, `sql_mode'
     Variable*            
     *Variable Name*      `sql_mode'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeset Default"     
     Valid                
     ValuesALLOW_INVALID_DATES,
     ANSI_QUOTES,         
     ERROR_FOR_DIVISION_BY_ZERO,
     HIGH_NOT_PRECEDENCE, 
     IGNORE_SPACE,        
     NO_AUTO_CREATE_USER, 
     NO_AUTO_VALUE_ON_ZERO,
     NO_BACKSLASH_ESCAPES,
     NO_DIR_IN_CREATE,    
     NO_ENGINE_SUBSTITUTION,
     NO_FIELD_OPTIONS,    
     NO_KEY_OPTIONS,      
     NO_TABLE_OPTIONS,    
     NO_UNSIGNED_SUBTRACTION,
     NO_ZERO_DATE,        
     NO_ZERO_IN_DATE,     
     ONLY_FULL_GROUP_BY,  
     PAD_CHAR_TO_FULL_LENGTH,
     PIPES_AS_CONCAT,     
     REAL_AS_FLOAT,       
     STRICT_ALL_TABLES,   
     STRICT_TRANS_TABLES  

     Set the SQL mode. See *Note server-sql-mode::.

   *  `--sysdate-is-now'

     *Command Line        `--sysdate-is-now'
     Format*              
     *Config File Format* `sysdate-is-now'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     `SYSDATE()' by default returns the time at which it executes, not
     the time at which the statement in which it occurs begins
     executing. This differs from the behavior of `NOW()'.  This option
     causes `SYSDATE()' to be an alias for `NOW()'. For information
     about the implications for binary logging and replication, see the
     description for `SYSDATE()' in *Note date-and-time-functions:: and
     for `SET TIMESTAMP' in *Note server-session-variables::.

   *  `--tc-heuristic-recover={COMMIT|ROLLBACK}'

     *Command Line        `--tc-heuristic-recover=name'
     Format*              
     *Config File Format* `tc-heuristic-recover'
     *Value Set *         
     Typeenumeration      
     Valid ValuesCOMMIT,  
     RECOVER              

     The type of decision to use in the heuristic recovery process.
     Currently, this option is unused.

   *  `--temp-pool'

     *Command Line        `--temp-pool'
     Format*              
     *Config File Format* `temp-pool'
     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     This option causes most temporary files created by the server to
     use a small set of names, rather than a unique name for each new
     file. This works around a problem in the Linux kernel dealing with
     creating many new files with different names.  With the old
     behavior, Linux seems to `leak' memory, because it is being
     allocated to the directory entry cache rather than to the disk
     cache. As of MySQL 6.0.10, this option is ignored except on Linux.

   *  `--transaction-isolation=LEVEL'

     *Command Line        `--transaction-isolation=name'
     Format*              
     *Config File Format* `transaction-isolation'
     *Value Set *         
     Typeenumeration      
     Valid                
     ValuesREAD-UNCOMMITTED,
     READ-COMMITTED,      
     REPEATABLE-READ,     
     SERIALIZABLE         

     Sets the default transaction isolation level. The `level' value
     can be `READ-UNCOMMITTED', `READ-COMMITTED', `REPEATABLE-READ', or
     `SERIALIZABLE'. See *Note set-transaction::.

   *  `--tmpdir=PATH', `-t PATH'

     *Command Line        `--tmpdir=name'
     Format*              
     *Config File Format* `tmpdir'
     *Option Sets         Yes, `tmpdir'
     Variable*            
     *Variable Name*      `tmpdir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path of the directory to use for creating temporary files.  It
     might be useful if your default `/tmp' directory resides on a
     partition that is too small to hold temporary tables. This option
     accepts several paths that are used in round-robin fashion. Paths
     should be separated by colon characters (``:'') on Unix and
     semicolon characters (``;'') on Windows, NetWare, and OS/2. If the
     MySQL server is acting as a replication slave, you should not set
     `--tmpdir' to point to a directory on a memory-based file system
     or to a directory that is cleared when the server host restarts.
     For more information about the storage location of temporary
     files, see *Note temporary-files::. A replication slave needs some
     of its temporary files to survive a machine restart so that it can
     replicate temporary tables or *Note `LOAD DATA INFILE': load-data.
     operations. If files in the temporary file directory are lost when
     the server restarts, replication fails.

   *  `--user={USER_NAME|USER_ID}', `-u {USER_NAME|USER_ID}'

     *Command Line        `--user=name'
     Format*              
     *Config File Format* `user'
     *Value Set *         
     Typestring           

     Run the *Note `mysqld': mysqld. server as the user having the name
     USER_NAME or the numeric user ID USER_ID.  (`User' in this context
     refers to a system login account, not a MySQL user listed in the
     grant tables.)

     This option is _mandatory_ when starting *Note `mysqld': mysqld.
     as `root'. The server changes its user ID during its startup
     sequence, causing it to run as that particular user rather than as
     `root'. See *Note security-guidelines::.

     To avoid a possible security hole where a user adds a
     `--user=root' option to a `my.cnf' file (thus causing the server to
     run as `root'), *Note `mysqld': mysqld.  uses only the first
     `--user' option specified and produces a warning if there are
     multiple `--user' options. Options in `/etc/my.cnf' and
     `$MYSQL_HOME/my.cnf' are processed before command-line options, so
     it is recommended that you put a `--user' option in `/etc/my.cnf'
     and specify a value other than `root'. The option in `/etc/my.cnf'
     is found before any other `--user' options, which ensures that the
     server runs as a user other than `root', and that a warning
     results if any other `--user' option is found.

   *  `--verbose', `-v'

     Use this option with the `--help' option for detailed help.

   *  `--version', `-V'

     Display version information and exit.

You can assign a value to a server system variable by using an option
of the form `--VAR_NAME=VALUE'.  For example, `--key_buffer_size=32M'
sets the `key_buffer_size' variable to a value of 32MB.

Note that when you assign a value to a variable, MySQL might
automatically correct the value to stay within a given range, or adjust
the value to the closest allowable value if only certain values are
allowed.

If you want to restrict the maximum value to which a variable can be
set at runtime with *Note `SET': set-option, you can define this by
using the `--maximum-VAR_NAME=VALUE' command-line option.

You can change the values of most system variables for a running server
with the *Note `SET': set-option.  statement. See *Note set-option::.

*Note server-system-variables::, provides a full description for all
variables, and additional information for setting them at server
startup and runtime.  *Note server-parameters::, includes information on
optimizing the server by tuning system variables.


File: manual.info,  Node: server-system-variables,  Next: server-session-variables,  Prev: server-options,  Up: mysqld-server

5.1.3 Server System Variables
-----------------------------

The MySQL server maintains many system variables that indicate how it
is configured. Each system variable has a default value. System
variables can be set at server startup using options on the command
line or in an option file. Most of them can be changed dynamically
while the server is running by means of the *Note `SET': set-option.
statement, which enables you to modify operation of the server without
having to stop and restart it. You can refer to system variable values
in expressions.

There are several ways to see the names and values of system variables:

   * To see the values that a server will use based on its compiled-in
     defaults and any option files that it reads, use this command:

          mysqld --verbose --help

   * To see the values that a server will use based on its compiled-in
     defaults, ignoring the settings in any option files, use this
     command:

          mysqld --no-defaults --verbose --help

   * To see the current values used by a running server, use the *Note
     `SHOW VARIABLES': show-variables. statement.

This section provides a description of each system variable.  Variables
with no version indicated are present in all MySQL 6.0 releases. For
historical information concerning their implementation, please see
`http://dev.mysql.com/doc/refman/5.1/en/',
`http://dev.mysql.com/doc/refman/5.0/en/', and
`http://dev.mysql.com/doc/refman/4.1/en/'.

The following table lists all available system variables:

*`mysqld' System Variable Summary*

*Name*                        *Cmd-Line**Option *System *Var    *Dynamic*
                                      file*   Var*    Scope*  
auto_increment_increment      Yes     Yes     Yes     Both    Yes
auto_increment_offset         Yes     Yes     Yes     Both    Yes
autocommit                                    Yes     Session Yes
automatic_sp_privileges                       Yes     Global  Yes
back_log                      Yes     Yes     Yes     Global  No
backup_history_log            Yes     Yes     Yes     Global  Yes
backup_history_log_file       Yes     Yes     Yes     Global  Yes
backup_progress_log           Yes     Yes     Yes     Global  Yes
backup_progress_log_file      Yes     Yes     Yes     Global  Yes
backup_wait_timeout                           Yes     Session Yes
backupdir                     Yes     Yes     Yes     Global  Yes
basedir                       Yes     Yes     Yes     Global  No
big-tables                    Yes     Yes                     Yes
- _Variable_: big_tables                      Yes     Session Yes
binlog_cache_size             Yes     Yes     Yes     Global  Yes
binlog-format                 Yes     Yes                     Yes
- _Variable_: binlog_format                   Yes     Both    Yes
bulk_insert_buffer_size       Yes     Yes     Yes     Both    Yes
character_set_client                          Yes     Both    Yes
character_set_connection                      Yes     Both    Yes
character_set_database This                   Yes     Both    Yes
option is dynamic, but only                                   
the server should set this                                    
information. You should not                                   
set the value of this                                         
variable manually.                                            
character-set-filesystem      Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
character_set_filesystem                                      
character_set_results                         Yes     Both    Yes
character-set-server          Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
character_set_server                                          
character_set_system                          Yes     Global  No
character-sets-dir            Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
character_sets_dir                                            
collation_connection                          Yes     Both    Yes
collation_database This                       Yes     Both    Yes
option is dynamic, but only                                   
the server should set this                                    
information. You should not                                   
set the value of this                                         
variable manually.                                            
collation-server              Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
collation_server                                              
completion_type               Yes     Yes     Yes     Both    Yes
concurrent_insert             Yes     Yes     Yes     Global  Yes
connect_timeout               Yes     Yes     Yes     Global  Yes
datadir                       Yes     Yes     Yes     Global  No
date_format                                   Yes     Both    Yes
datetime_format               Yes     Yes     Yes     Both    Yes
debug                         Yes     Yes     Yes     Both    Yes
debug_sync                                    Yes     Both    Yes
default_week_format           Yes     Yes     Yes     Both    Yes
delay-key-write               Yes     Yes                     Yes
- _Variable_: delay_key_write                 Yes     Global  Yes
delayed_insert_limit          Yes     Yes     Yes     Global  Yes
delayed_insert_timeout        Yes     Yes     Yes     Global  Yes
delayed_queue_size            Yes     Yes     Yes     Global  Yes
div_precision_increment       Yes     Yes     Yes     Both    Yes
engine-condition-pushdown     Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
engine_condition_pushdown                                     
error_count                                   Yes     Session No
event-scheduler               Yes     Yes                     Yes
- _Variable_: event_scheduler                 Yes     Global  Yes
expire_logs_days              Yes     Yes     Yes     Global  Yes
falcon_checkpoint_schedule    Yes     Yes     Yes     Global  Yes
falcon_checksums              Yes     Yes     Yes     Global  Yes
falcon_consistent_read        Yes     Yes     Yes     Both    Yes
falcon_debug_mask             Yes     Yes     Yes     Global  Yes
falcon_debug_server           Yes     Yes     Yes     Global  No
falcon_disable_fsync          Yes     Yes     Yes     Global  Yes
falcon_gopher_threads         Yes     Yes     Yes     Global  No
falcon_index_chill_threshold  Yes     Yes     Yes     Global  Yes
falcon_initial_allocation     Yes     Yes     Yes     Global  Yes
falcon_io_threads             Yes     Yes     Yes     Global  Yes
falcon_large_blob_threshold   Yes     Yes     Yes     Global  No
falcon_lock_wait_timeout      Yes     Yes     Yes     Global  Yes
falcon_max_transaction_backlogYes     Yes     Yes     Global  Yes
falcon_page_cache_size        Yes     Yes     Yes     Global  No
falcon_page_size              Yes     Yes     Yes     Global  No
falcon_record_chill_threshold Yes     Yes     Yes     Global  Yes
falcon_record_memory_max      Yes     Yes     Yes     Global  Yes
falcon_record_scavenge_floor  Yes     Yes     Yes     Global  Yes
falcon_record_scavenge_thresholdYes     Yes     Yes     Global  Yes
falcon_scavenge_schedule      Yes     Yes     Yes     Global  No
falcon_serial_log_buffers     Yes     Yes     Yes     Global  No
falcon_serial_log_dir         Yes     Yes     Yes     Global  No
falcon_serial_log_priority    Yes     Yes     Yes     Global  Yes
falcon_support_xa             Yes     Yes     Yes     Global  No
falcon_use_deferred_index_hashYes     Yes     Yes     Global  No
falcon_use_sectorcache        Yes     Yes     Yes     Global  No
falcon_use_supernodes         Yes     Yes     Yes     Global  No
flush                         Yes     Yes     Yes     Global  Yes
flush_time                    Yes     Yes     Yes     Global  Yes
foreign_key_checks                            Yes     Session Yes
ft_boolean_syntax             Yes     Yes     Yes     Global  Yes
ft_max_word_len               Yes     Yes     Yes     Global  No
ft_min_word_len               Yes     Yes     Yes     Global  No
ft_query_expansion_limit      Yes     Yes     Yes     Global  No
ft_stopword_file              Yes     Yes     Yes     Global  No
general-log                   Yes     Yes                     Yes
- _Variable_: general_log                     Yes     Global  Yes
general_log_file              Yes     Yes     Yes     Global  Yes
group_concat_max_len          Yes     Yes     Yes     Both    Yes
have_compress                                 Yes     Global  No
have_crypt                                    Yes     Global  No
have_csv                                      Yes     Global  No
have_dynamic_loading                          Yes     Global  No
have_geometry                                 Yes     Global  No
have_innodb                                   Yes     Global  No
have_ndbcluster                               Yes     Global  No
have_openssl                                  Yes     Global  No
have_partitioning                             Yes     Global  No
have_query_cache                              Yes     Global  No
have_rtree_keys                               Yes     Global  No
have_ssl                                      Yes     Global  No
have_symlink                                  Yes     Global  No
hostname                                      Yes     Global  No
identity                                      Yes     Session Yes
init_connect                  Yes     Yes     Yes     Global  Yes
init-file                     Yes     Yes                     No
- _Variable_: init_file                       Yes     Global  No
init_slave                    Yes     Yes     Yes     Global  Yes
innodb_adaptive_hash_index    Yes     Yes     Yes     Global  No
innodb_additional_mem_pool_sizeYes     Yes     Yes     Global  No
innodb_autoextend_increment   Yes     Yes     Yes     Global  Yes
innodb_autoinc_lock_mode      Yes     Yes     Yes     Global  No
innodb_buffer_pool_size       Yes     Yes     Yes     Global  No
innodb_checksums              Yes     Yes     Yes     Global  No
innodb_commit_concurrency     Yes     Yes     Yes     Global  Yes
innodb_concurrency_tickets    Yes     Yes     Yes     Global  Yes
innodb_data_file_path         Yes     Yes     Yes     Global  No
innodb_data_home_dir          Yes     Yes     Yes     Global  No
innodb_doublewrite            Yes     Yes     Yes     Global  No
innodb_fast_shutdown          Yes     Yes     Yes     Global  Yes
innodb_file_io_threads        Yes     Yes     Yes     Global  No
innodb_file_per_table         Yes     Yes     Yes     Global  No
innodb_flush_log_at_trx_commitYes     Yes     Yes     Global  Yes
innodb_flush_method           Yes     Yes     Yes     Global  No
innodb_force_recovery         Yes     Yes     Yes     Global  No
innodb_lock_wait_timeout      Yes     Yes     Yes     Global  No
innodb_locks_unsafe_for_binlogYes     Yes     Yes     Global  No
innodb_log_buffer_size        Yes     Yes     Yes     Global  No
innodb_log_file_size          Yes     Yes     Yes     Global  No
innodb_log_files_in_group     Yes     Yes     Yes     Global  No
innodb_log_group_home_dir     Yes     Yes     Yes     Global  No
innodb_max_dirty_pages_pct    Yes     Yes     Yes     Global  Yes
innodb_max_purge_lag          Yes     Yes     Yes     Global  Yes
innodb_mirrored_log_groups    Yes     Yes     Yes     Global  No
innodb_open_files             Yes     Yes     Yes     Global  No
innodb_rollback_on_timeout    Yes     Yes     Yes     Global  No
innodb_stats_on_metadata      Yes     Yes     Yes     Global  Yes
innodb_support_xa             Yes     Yes     Yes     Both    Yes
innodb_sync_spin_loops        Yes     Yes     Yes     Global  Yes
innodb_table_locks            Yes     Yes     Yes     Both    Yes
innodb_thread_concurrency     Yes     Yes     Yes     Global  Yes
innodb_thread_sleep_delay     Yes     Yes     Yes     Global  Yes
insert_id                                     Yes     Session Yes
interactive_timeout           Yes     Yes     Yes     Both    Yes
join_buffer_size              Yes     Yes     Yes     Both    Yes
join_cache_level              Yes     Yes     Yes     Both    Yes
keep_files_on_create          Yes     Yes     Yes     Both    Yes
key_buffer_size               Yes     Yes     Yes     Global  Yes
key_cache_age_threshold       Yes     Yes     Yes     Global  Yes
key_cache_block_size          Yes     Yes     Yes     Global  Yes
key_cache_division_limit      Yes     Yes     Yes     Global  Yes
language                      Yes     Yes     Yes     Global  No
large_page_size                               Yes     Global  No
large-pages                   Yes     Yes                     No
- _Variable_: large_pages                     Yes     Global  No
last_insert_id                                Yes     Session Yes
lc_time_names                                 Yes     Both    Yes
license                                       Yes     Global  No
local_infile                                  Yes     Global  Yes
locked_in_memory                              Yes     Global  No
log                           Yes     Yes     Yes     Global  Yes
log-backup-output             Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
log_backup_output                                             
log_bin                                       Yes     Global  No
log-bin                       Yes     Yes     Yes     Global  No
log-bin-trust-function-creatorsYes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
log_bin_trust_function_creators                                
log-error                     Yes     Yes                     No
- _Variable_: log_error                       Yes     Global  No
log-output                    Yes     Yes                     Yes
- _Variable_: log_output                      Yes     Global  Yes
log-queries-not-using-indexes Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
log_queries_not_using_indexes                                 
log-slave-updates             Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
log_slave_updates                                             
log-slow-queries              Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
log_slow_queries                                              
log-warnings                  Yes     Yes                     Yes
- _Variable_: log_warnings                    Yes     Both    Yes
long_query_time               Yes     Yes     Yes     Both    Yes
low-priority-updates          Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
low_priority_updates                                          
lower_case_file_system        Yes     Yes     Yes     Global  No
lower_case_table_names        Yes     Yes     Yes     Global  No
maria-block-size              Yes     Yes                     No
- _Variable_:                                 Yes             No
maria_block_size                                              
maria-checkpoint-interval     Yes     Yes     Yes     Global  Yes
maria-log-file-size           Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
maria_log_file_size                                           
maria-log-purge-type          Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
maria_log_purge_type                                          
maria-max-sort-file-size      Yes     Yes     Yes     Global  Yes
maria-page-checksum           Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
maria_page_checksum                                           
maria-pagecache-age-threshold Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
maria_pagecache_age_threshold                                 
maria-pagecache-buffer-size   Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
maria_pagecache_buffer_size                                   
maria-pagecache-division-limitYes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
maria_pagecache_division_limit                                
maria-recover                 Yes     Yes                     Yes
- _Variable_: maria_recover                   Yes     Global  Yes
maria-repair-threads          Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
maria_repair_threads                                          
maria-sort-buffer-size        Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
maria_sort_buffer_size                                        
maria-stats-method            Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
maria_stats_method                                            
maria-sync-log-dir            Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
maria_sync_log_dir                                            
*Note master-bind:            Yes     Yes     Yes             No
replication-options.                                          
max_allowed_packet            Yes     Yes     Yes     Both    Yes
max_binlog_cache_size         Yes     Yes     Yes     Global  Yes
max_binlog_size               Yes     Yes     Yes     Global  Yes
max_connect_errors            Yes     Yes     Yes     Global  Yes
max_connections               Yes     Yes     Yes     Global  Yes
max_delayed_threads           Yes     Yes     Yes     Both    Yes
max_error_count               Yes     Yes     Yes     Both    Yes
max_heap_table_size           Yes     Yes     Yes     Both    Yes
max_insert_delayed_threads                    Yes     Both    Yes
max_join_size                 Yes     Yes     Yes     Both    Yes
max_length_for_sort_data      Yes     Yes     Yes     Both    Yes
max_prepared_stmt_count       Yes     Yes     Yes     Global  Yes
max_relay_log_size            Yes     Yes     Yes     Global  Yes
max_seeks_for_key             Yes     Yes     Yes     Both    Yes
max_sort_length               Yes     Yes     Yes     Both    Yes
max_sp_recursion_depth        Yes     Yes     Yes     Both    Yes
max_tmp_tables                Yes     Yes     Yes     Both    Yes
max_user_connections          Yes     Yes     Yes     Both    Yes
max_write_lock_count          Yes     Yes     Yes     Global  Yes
memlock                       Yes     Yes     Yes     Global  No
min-examined-row-limit        Yes     Yes     Yes     Both    Yes
myisam_data_pointer_size      Yes     Yes     Yes     Global  Yes
myisam_max_sort_file_size     Yes     Yes     Yes     Global  Yes
myisam_recover_options                        Yes     Global  No
myisam_repair_threads         Yes     Yes     Yes     Both    Yes
myisam_sort_buffer_size       Yes     Yes     Yes     Both    Yes
myisam_stats_method           Yes     Yes     Yes     Both    Yes
myisam_use_mmap               Yes     Yes     Yes     Global  Yes
named_pipe                                    Yes     Global  No
ndb_autoincrement_prefetch_sz Yes     Yes     Yes     Both    Yes
net_buffer_length             Yes     Yes     Yes     Both    Yes
net_read_timeout              Yes     Yes     Yes     Both    Yes
net_retry_count               Yes     Yes     Yes     Both    Yes
net_write_timeout             Yes     Yes     Yes     Both    Yes
new                           Yes     Yes     Yes     Both    Yes
old                           Yes     Yes     Yes     Global  No
old-passwords                 Yes     Yes                     Yes
- _Variable_: old_passwords                   Yes     Both    Yes
open-files-limit              Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
open_files_limit                                              
optimizer_prune_level         Yes     Yes     Yes     Both    Yes
optimizer_search_depth        Yes     Yes     Yes     Both    Yes
optimizer_switch              Yes     Yes     Yes     Both    Yes
optimizer_use_mrr                             Yes     Both    Yes
pid-file                      Yes     Yes                     No
- _Variable_: pid_file                        Yes     Global  No
plugin_dir                    Yes     Yes     Yes     Global  No
port                          Yes     Yes     Yes     Global  No
preload_buffer_size           Yes     Yes     Yes     Both    Yes
prepared_stmt_count                           Yes     Global  No
profiling                                     Yes     Session Yes
profiling_history_size                        Yes     Both    Yes
protocol_version                              Yes     Global  No
query_alloc_block_size        Yes     Yes     Yes     Both    Yes
query_cache_limit             Yes     Yes     Yes     Global  Yes
query_cache_min_res_unit      Yes     Yes     Yes     Global  Yes
query_cache_size              Yes     Yes     Yes     Global  Yes
query_cache_type              Yes     Yes     Yes     Both    Yes
query_cache_wlock_invalidate  Yes     Yes     Yes     Both    Yes
query_prealloc_size           Yes     Yes     Yes     Both    Yes
rand_seed1                                    Yes     Session Yes
rand_seed2                                    Yes     Session Yes
range_alloc_block_size        Yes     Yes     Yes     Both    Yes
read_buffer_size              Yes     Yes     Yes     Both    Yes
read_only                     Yes     Yes     Yes     Global  Yes
read_rnd_buffer_size          Yes     Yes     Yes     Both    Yes
relay_log_purge               Yes     Yes     Yes     Global  Yes
relay_log_recovery            Yes     Yes     Yes     Global  Yes
relay_log_space_limit         Yes     Yes     Yes     Global  No
report-host                   Yes     Yes                     No
- _Variable_: report_host                     Yes     Global  No
report-password               Yes     Yes                     No
- _Variable_: report_password                 Yes     Global  No
report-port                   Yes     Yes                     No
- _Variable_: report_port                     Yes     Global  No
report-user                   Yes     Yes                     No
- _Variable_: report_user                     Yes     Global  No
rpl_recovery_rank                             Yes     Global  Yes
rpl_semi_sync_master_enabled                  Yes     Global  Yes
rpl_semi_sync_master_reply_log_file_pos                Yes     Global  Yes
rpl_semi_sync_master_timeout                  Yes     Global  Yes
rpl_semi_sync_master_trace_level                Yes     Global  Yes
rpl_semi_sync_slave_enabled                   Yes     Global  Yes
rpl_semi_sync_slave_trace_level                Yes     Global  Yes
secure-auth                   Yes     Yes                     Yes
- _Variable_: secure_auth                     Yes     Global  Yes
secure-backup-file-priv       Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
secure_backup_file_priv                                       
secure-file-priv              Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
secure_file_priv                                              
server-id                     Yes     Yes                     Yes
- _Variable_: server_id                       Yes     Global  Yes
shared_memory                                 Yes     Global  No
shared_memory_base_name                       Yes     Global  No
skip-external-locking         Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
skip_external_locking                                         
skip-networking               Yes     Yes                     No
- _Variable_: skip_networking                 Yes     Global  No
skip-show-database            Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
skip_show_database                                            
slave_compressed_protocol     Yes     Yes     Yes     Global  Yes
slave_exec_mode                               Yes     Global  Yes
*Note slave-load-tmpdir:      Yes     Yes                     No
replication-options.                                          
- _Variable_:                                 Yes     Global  No
slave_load_tmpdir                                             
slave-net-timeout             Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
slave_net_timeout                                             
slave-skip-errors             Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
slave_skip_errors                                             
slave_transaction_retries     Yes     Yes     Yes     Global  Yes
slow_launch_time              Yes     Yes     Yes     Global  Yes
slow-query-log                Yes     Yes                     Yes
- _Variable_: slow_query_log                  Yes     Global  Yes
slow_query_log_file           Yes     Yes     Yes     Global  Yes
socket                        Yes     Yes     Yes     Global  No
sort_buffer_size              Yes     Yes     Yes     Both    Yes
sql_auto_is_null                              Yes     Session Yes
sql_big_selects                               Yes     Session Yes
sql_big_tables                                Yes     Session Yes
sql_buffer_result                             Yes     Session Yes
sql_log_bin                                   Yes     Session Yes
sql_log_off                                   Yes     Session Yes
sql_log_update                                Yes     Session Yes
sql_low_priority_updates                      Yes     Both    Yes
sql_max_join_size                             Yes     Both    Yes
sql-mode                      Yes     Yes                     Yes
- _Variable_: sql_mode                        Yes     Both    Yes
sql_notes                                     Yes     Session Yes
sql_quote_show_create                         Yes     Session Yes
sql_safe_updates                              Yes     Session Yes
sql_select_limit                              Yes     Both    Yes
sql_slave_skip_counter                        Yes     Global  Yes
sql_warnings                                  Yes     Session Yes
ssl-ca                        Yes     Yes                     No
- _Variable_: ssl_ca                          Yes     Global  No
ssl-capath                    Yes     Yes                     No
- _Variable_: ssl_capath                      Yes     Global  No
ssl-cert                      Yes     Yes                     No
- _Variable_: ssl_cert                        Yes     Global  No
ssl-cipher                    Yes     Yes                     No
- _Variable_: ssl_cipher                      Yes     Global  No
ssl-key                       Yes     Yes                     No
- _Variable_: ssl_key                         Yes     Global  No
storage_engine                                Yes     Both    Yes
sync-binlog                   Yes     Yes                     Yes
- _Variable_: sync_binlog                     Yes     Global  Yes
sync-frm                      Yes     Yes                     Yes
- _Variable_: sync_frm                        Yes     Global  Yes
sync-master-info              Yes     Yes     Yes     Global  Yes
sync-relay-log                Yes     Yes     Yes     Global  Yes
sync-relay-log-info           Yes     Yes     Yes     Global  Yes
system_time_zone                              Yes     Global  No
table_cache                   Yes     Yes     Yes     Global  Yes
table_definition_cache        Yes     Yes     Yes     Global  Yes
table_lock_wait_timeout       Yes     Yes     Yes     Global  Yes
table_open_cache              Yes     Yes     Yes     Global  Yes
thread_cache_size             Yes     Yes     Yes     Global  Yes
thread_concurrency            Yes     Yes     Yes     Global  No
thread_handling               Yes     Yes     Yes     Global  No
thread_pool_size              Yes     Yes     Yes     Global  No
thread_stack                  Yes     Yes     Yes     Global  No
time_format                   Yes     Yes     Yes     Both    Yes
time_zone                     Yes     Yes     Yes     Both    Yes
timed_mutexes                 Yes     Yes     Yes     Global  Yes
timestamp                                     Yes     Session Yes
tmp_table_size                Yes     Yes     Yes     Both    Yes
tmpdir                        Yes     Yes     Yes     Global  No
transaction_alloc_block_size  Yes     Yes     Yes     Both    Yes
transaction_prealloc_size     Yes     Yes     Yes     Both    Yes
tx_isolation                                  Yes     Both    Yes
unique_checks                                 Yes     Session Yes
updatable_views_with_limit    Yes     Yes     Yes     Both    Yes
version                       Yes     Yes     Yes     Global  No
version_comment                               Yes     Global  No
version_compile_machine                       Yes     Global  No
version_compile_os                            Yes     Global  No
wait_timeout                  Yes     Yes     Yes     Both    Yes
warning_count                                 Yes     Session No

For additional system variable information, see these sections:

   * *Note server-session-variables::, describes system variables that
     exist only as session variables (that is, they do not have any
     global counterpart).

   * *Note using-system-variables::, discusses the syntax for setting
     and displaying system variable values.

   * *Note dynamic-system-variables::, lists the variables that can be
     set at runtime.

   * Information on tuning system variables can be found in *Note
     server-parameters::.

   * *Note innodb-parameters::, lists `InnoDB' system variables.

   * For information on server system variables specific to
     replication, see *Note replication-options::.

*Note*:

Some of the following variable descriptions refer to `enabling' or
`disabling' a variable.  These variables can be enabled with the *Note
`SET': set-option.  statement by setting them to `ON' or `1', or
disabled by setting them to `OFF' or `0'. However, to set such a
variable on the command line or in an option file, you must set it to
`1' or `0'; setting it to `ON' or `OFF' will not work. For example, on
the command line, `--delay_key_write=1' works but
`--delay_key_write=ON' does not.

Values for buffer sizes, lengths, and stack sizes are given in bytes
unless otherwise specified.

Some system variables control the size of buffers or caches. For a
given buffer, the server might need to allocate internal data
structures. These structures typically are allocated from the total
memory allocated to the buffer, and the amount of space required might
be platform dependent. This means that when you assign a value to a
system variable that controls a buffer size, the amount of space
actually available might differ from the value assigned. In some cases,
the amount might be less than the value assigned. It is also possible
that the server will adjust a value upward. For example, if you assign
a value of 0 to a variable for which the minimal value is 1024, the
server will set the value to 1024.

   *  `automatic_sp_privileges'

     *Variable Name*      `automatic_sp_privileges'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     When this variable has a value of 1 (the default), the server
     automatically grants the `EXECUTE' and `ALTER ROUTINE' privileges
     to the creator of a stored routine, if the user cannot already
     execute and alter or drop the routine. (The `ALTER ROUTINE'
     privilege is required to drop the routine.) The server also
     automatically drops those privileges when the creator drops the
     routine. If `automatic_sp_privileges' is 0, the server does not
     automatically add or drop these privileges.

   *  `backup_history_log'

     *Version Introduced* 6.0.8
     *Command Line        `--backup_history_log'
     Format*              
     *Config File Format* `backup_history_log'
     *Option Sets         Yes, `backup_history_log'
     Variable*            
     *Variable Name*      `backup_history_log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultON            

     Whether the MySQL Backup history log is enabled. The value can be
     0 (or `OFF') to disable the log or 1 (or `ON') to enable the log.
     The destination for log output is controlled by the
     `log_backup_output' system variable; if that value is `NONE', no
     log entries are written even if the log is enabled. This variable
     was added in MySQL 6.0.8.

   *  `backup_history_log_file'

     *Version Introduced* 6.0.8
     *Command Line        `--backup_history_log_file'
     Format*              
     *Config File Format* `backup_history_log_file'
     *Option Sets         Yes, `backup_history_log_file'
     Variable*            
     *Variable Name*      `backup_history_log_file'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typefilename         
     Defaultbackup_history.log

     The name of the MySQL Backup history log file. The default value
     is `backup_history.log'. This variable was added in MySQL 6.0.8.

   *  `backup_progress_log'

     *Version Introduced* 6.0.8
     *Command Line        `--backup_progress_log'
     Format*              
     *Config File Format* `backup_progress_log'
     *Option Sets         Yes, `backup_progress_log'
     Variable*            
     *Variable Name*      `backup_progress_log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultON            

     Whether the MySQL Backup progress log is enabled. The value can be
     0 (or `OFF') to disable the log or 1 (or `ON') to enable the log.
     The destination for log output is controlled by the
     `log_backup_output' system variable; if that value is `NONE', no
     log entries are written even if the log is enabled. This variable
     was added in MySQL 6.0.8.

   *  `backup_progress_log_file'

     *Version Introduced* 6.0.8
     *Command Line        `--backup_progress_log_file'
     Format*              
     *Config File Format* `backup_progress_log_file'
     *Option Sets         Yes, `backup_progress_log_file'
     Variable*            
     *Variable Name*      `backup_progress_log_file'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typefilename         
     Defaultbackup_progress.log

     The name of the MySQL Backup progress log file. The default value
     is `backup_progress.log'. This variable was added in MySQL 6.0.8.

   *  `back_log'

     *Command Line        `--back_log=#'
     Format*              
     *Config File Format* `back_log'
     *Option Sets         Yes, `back_log'
     Variable*            
     *Variable Name*      `back_log'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default50            
     Range1-65535         

     The number of outstanding connection requests MySQL can have.
     This comes into play when the main MySQL thread gets very many
     connection requests in a very short time. It then takes some time
     (although very little) for the main thread to check the connection
     and start a new thread. The `back_log' value indicates how many
     requests can be stacked during this short time before MySQL
     momentarily stops answering new requests. You need to increase
     this only if you expect a large number of connections in a short
     period of time.

     In other words, this value is the size of the listen queue for
     incoming TCP/IP connections. Your operating system has its own
     limit on the size of this queue. The manual page for the Unix
     `listen()' system call should have more details. Check your OS
     documentation for the maximum value for this variable. `back_log'
     cannot be set higher than your operating system limit.

   *  `backupdir'

     *Version Introduced* 6.0.7
     *Command Line        `--backupdir=name'
     Format*              
     *Config File Format* `backupdir'
     *Option Sets         Yes, `backupdir'
     Variable*            
     *Variable Name*      `backupdir'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typefilename         

     The path to the default image file directory for *Note `BACKUP
     DATABASE': backup-database. and *Note `RESTORE': restore.
     operations. If an image file is named as a relative path name, it
     is interpreted relative to the value of `backupdir'. If the value
     of `backupdir' is itself a relative path name, its value is
     interpreted relative to the data directory. The default value is
     the data directory.

     If `backupdir' is set to a non-existent path, *Note `BACKUP
     DATABASE': backup-database. and *Note `RESTORE': restore.  cannot
     be executed. The same is true if `backupdir' references a symbolic
     link that points at a non-existent path. Specifying the backup
     image file name as an absolute path name does not help.

     If `backupdir' is set to an existing plain file or pipe, *Note
     `BACKUP DATABASE': backup-database. and *Note `RESTORE': restore.
     fail if the value is a relative path, unless it starts with a
     leading `../' component or unless the backup image file name is
     given as an absolute path. The same is true if `backupdir'
     references a symbolic link that points at an existent plain file
     or pipe.

     This variable was added in MySQL 6.0.7.

   *  `basedir'

     *Command Line        `--basedir=name'
     Format*              
     *Config File Format* `basedir'
     *Option Sets         Yes, `basedir'
     Variable*            
     *Variable Name*      `basedir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The MySQL installation base directory. This variable can be set
     with the `--basedir' option.  Relative path names for other
     variables usually are resolved relative to the base directory.

   *  `bulk_insert_buffer_size'

     *Command Line        `--bulk_insert_buffer_size=#'
     Format*              
     *Config File Format* `bulk_insert_buffer_size'
     *Option Sets         Yes, `bulk_insert_buffer_size'
     Variable*            
     *Variable Name*      `bulk_insert_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default8388608       
     Range0-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default8388608       
     Range0-18446744073709547520

     `MyISAM' uses a special tree-like cache to make bulk inserts
     faster for *Note `INSERT ... SELECT': insert-select, `INSERT ...
     VALUES (...), (...), ...', and *Note `LOAD DATA INFILE':
     load-data. when adding data to non-empty tables. This variable
     limits the size of the cache tree in bytes per thread. Setting it
     to 0 disables this optimization. The default value is 8MB.

   *  `character_set_client'

     *Variable Name*      `character_set_client'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The character set for statements that arrive from the client.  The
     session value of this variable is set using the character set
     requested by the client when the client connects to the server.
     (Many clients support a `--default-character-set' option to enable
     this character set to be specified explicitly. See also *Note
     charset-connection::.) The global value of the variable is used to
     set the session value in cases when the client-requested value is
     unknown or not available, or the server is configured to ignore
     client requests:

        * The client is from a version of MySQL older than MySQL 4.1,
          and thus does not request a character set.

        * The client requests a character set not known to the server.
          For example, a Japanese-enabled client requests `sjis' when
          connecting to a server not configured with `sjis' support.

        * *Note `mysqld': mysqld. was started with the
          `--skip-character-set-client-handshake' option, which causes
          it to ignore client character set configuration. This
          reproduces MySQL 4.0 behavior and is useful should you wish
          to upgrade the server without upgrading all the clients.

   *  `character_set_connection'

     *Variable Name*      `character_set_connection'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The character set used for literals that do not have a character
     set introducer and for number-to-string conversion.

   *  `character_set_database'

     *Variable Name*      `character_set_database'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Footnote*           This option is dynamic, but only the server
                          should set this information. You should not
                          set the value of this variable manually.
     *Value Set *         
     Typestring           

     The character set used by the default database. The server sets
     this variable whenever the default database changes. If there is
     no default database, the variable has the same value as
     `character_set_server'.

   *  `character_set_filesystem'

     *Command Line        `--character-set-filesystem=name'
     Format*              
     *Config File Format* `character-set-filesystem'
     *Option Sets         Yes, `character_set_filesystem'
     Variable*            
     *Variable Name*      `character_set_filesystem'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The file system character set. This variable is used to interpret
     string literals that refer to file names, such as in the *Note
     `LOAD DATA INFILE': load-data. and *Note `SELECT ... INTO
     OUTFILE': select. statements and the `LOAD_FILE()' function. Such
     file names are converted from `character_set_client' to
     `character_set_filesystem' before the file opening attempt occurs.
     The default value is `binary', which means that no conversion
     occurs. For systems on which multi-byte file names are allowed, a
     different value may be more appropriate. For example, if the
     system represents file names using UTF-8, set
     `character_set_filesystem' to `'utf8''.

   *  `character_set_results'

     *Variable Name*      `character_set_results'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The character set used for returning query results to the client.

   *  `character_set_server'

     *Command Line        `--character-set-server'
     Format*              
     *Config File Format* `character-set-server'
     *Option Sets         Yes, `character_set_server'
     Variable*            
     *Variable Name*      `character_set_server'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The server's default character set.

   *  `character_set_system'

     *Variable Name*      `character_set_system'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     The character set used by the server for storing identifiers.  The
     value is always `utf8'.

   *  `character_sets_dir'

     *Command Line        `--character-sets-dir=name'
     Format*              
     *Config File Format* `character-sets-dir'
     *Option Sets         Yes, `character_sets_dir'
     Variable*            
     *Variable Name*      `character-sets-dir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The directory where character sets are installed.

   *  `collation_connection'

     *Variable Name*      `collation_connection'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The collation of the connection character set.

   *  `collation_database'

     *Variable Name*      `collation_database'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Footnote*           This option is dynamic, but only the server
                          should set this information. You should not
                          set the value of this variable manually.
     *Value Set *         
     Typestring           

     The collation used by the default database. The server sets this
     variable whenever the default database changes. If there is no
     default database, the variable has the same value as
     `collation_server'.

   *  `collation_server'

     *Command Line        `--collation-server'
     Format*              
     *Config File Format* `collation-server'
     *Option Sets         Yes, `collation_server'
     Variable*            
     *Variable Name*      `collation_server'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The server's default collation.

   *  `completion_type'

     *Command Line        `--completion_type=#'
     Format*              
     *Config File Format* `completion_type'
     *Option Sets         Yes, `completion_type'
     Variable*            
     *Variable Name*      `competion_type'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0 Valid       
     Values0, 1, 2        

     The transaction completion type:

        * If the value is 0 (the default), *Note `COMMIT': commit. and
          *Note `ROLLBACK': commit.  are unaffected.

        * If the value is 1, *Note `COMMIT': commit.  and *Note
          `ROLLBACK': commit.  are equivalent to `COMMIT AND CHAIN' and
          `ROLLBACK AND CHAIN', respectively. (A new transaction starts
          immediately with the same isolation level as the
          just-terminated transaction.)

        * If the value is 2, *Note `COMMIT': commit.  and *Note
          `ROLLBACK': commit.  are equivalent to `COMMIT RELEASE' and
          `ROLLBACK RELEASE', respectively. (The server disconnects
          after terminating the transaction.)

   *  `concurrent_insert'

     *Command Line        `--concurrent_insert[=#]'
     Format*              
     *Config File Format* `concurrent_insert'
     *Option Sets         Yes, `concurrent_insert'
     Variable*            
     *Variable Name*      `concurrent_insert'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1 Valid       
     Values0, 1, 2        

     If 1 (the default), MySQL allows *Note `INSERT': insert. and *Note
     `SELECT': select. statements to run concurrently for `MyISAM'
     tables that have no free blocks in the middle of the data file.
     You can turn this option off by starting *Note `mysqld': mysqld.
     with `--safe-mode' or `--skip-new'.

     This variable can take three integer values.

     *Value* *Description*
     0       Off
     1       (Default) Enables concurrent insert for `MyISAM'
             tables that don't have holes
     2       Enables concurrent inserts for all `MyISAM'
             tables, even those that have holes. For a table
             with a hole, new rows are inserted at the end of
             the table if it is in use by another thread.
             Otherwise, MySQL acquires a normal write lock and
             inserts the row into the hole.

     See also *Note concurrent-inserts::.

   *  `connect_timeout'

     *Command Line        `--connect_timeout=#'
     Format*              
     *Config File Format* `connect_timeout'
     *Option Sets         Yes, `connect_timeout'
     Variable*            
     *Variable Name*      `connect_timeout'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default10            

     The number of seconds that the *Note `mysqld': mysqld.  server
     waits for a connect packet before responding with `Bad handshake'.
     The default value is 10 seconds.

     Increasing the `connect_timeout' value might help if clients
     frequently encounter errors of the form `Lost connection to MySQL
     server at 'XXX', system error: ERRNO'.

   *  `datadir'

     *Command Line        `--datadir=name'
     Format*              
     *Config File Format* `datadir'
     *Option Sets         Yes, `datadir'
     Variable*            
     *Variable Name*      `datadir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The MySQL data directory. This variable can be set with the
     `--datadir' option.

   *  `date_format'

     This variable is unused.

   *  `datetime_format'

     This variable is unused.

   *  `debug'

     *Command Line        `--debug[=debug_options]'
     Format*              
     *Config File Format* `debug'
     *Variable Name*      `debug'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           
     Default'd:t:o,/tmp/mysqld.trace

     This variable indicates the current debugging settings. It is
     available only for servers built with debugging support. The
     initial value comes from the value of instances of the `--debug'
     option given at server startup. The global and session values may
     be set at runtime; the `SUPER' privilege is required, even for the
     session value.

     Assigning a value that begins with `+' or `-' cause the value to
     added to or subtracted from the current value:

          mysql> SET debug = 'T';
          mysql> SELECT @@debug;
          +---------+
          | @@debug |
          +---------+
          | T       |
          +---------+

          mysql> SET debug = '+P';
          mysql> SELECT @@debug;
          +---------+
          | @@debug |
          +---------+
          | P:T     |
          +---------+

          mysql> SET debug = '-P';
          mysql> SELECT @@debug;
          +---------+
          | @@debug |
          +---------+
          | T       |
          +---------+

   *  `debug_sync'

     *Version Introduced* 6.0.6
     *Variable Name*      `debug_sync'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     This variable is the user interface to the Debug Sync facility.
     Use of Debug Sync requires that MySQL be configured with the
     `--enable-debug-sync' option (see *Note configure-options::). If
     Debug Sync is not compiled in, this system variable is not
     available.

     The global variable value is read only and indicates whether the
     facility is enabled. By default, Debug Sync is disabled and the
     value of `debug_sync' is `OFF'. If the server is started with
     `--debug-sync-timeout=N', where N is a timeout value greater than
     0, Debug Sync is enabled and the value of `debug_sync' is `ON -
     current signal' followed by the signal name. Also, N becomes the
     default timeout for individual synchronization points.

     The session value can be read by any user and will have the same
     value as the global variable. The session value can be set by
     users that have the `SUPER' privilege to control synchronization
     points.

     For a description of the Debug Sync facility and how to use
     synchronization points, see MySQL Internals: Test Synchronization
     (http://forge.mysql.com/wiki/MySQL_Internals_Test_Synchronization).

     This variable was added in MySQL 6.0.6.

   *  `default_week_format'

     *Command Line        `--default_week_format=#'
     Format*              
     *Config File Format* `default_week_format'
     *Option Sets         Yes, `default_week_format'
     Variable*            
     *Variable Name*      `default_week_format'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0 Range0-7    

     The default mode value to use for the `WEEK()' function. See *Note
     date-and-time-functions::.

   *  `delay_key_write'

     *Command Line        `--delay-key-write[=name]'
     Format*              
     *Config File Format* `delay-key-write'
     *Option Sets         Yes, `delay_key_write'
     Variable*            
     *Variable Name*      `delay-key-write'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultON Valid      
     ValuesON, OFF, ALL   

     This option applies only to `MyISAM' tables.  It can have one of
     the following values to affect handling of the `DELAY_KEY_WRITE'
     table option that can be used in *Note `CREATE TABLE':
     create-table.  statements.

     *Option**Description*
     `OFF'   `DELAY_KEY_WRITE' is ignored.
     `ON'    MySQL honors any `DELAY_KEY_WRITE' option
             specified in *Note `CREATE TABLE': create-table.
             statements. This is the default value.
     `ALL'   All new opened tables are treated as if they were
             created with the `DELAY_KEY_WRITE' option enabled.

     If `DELAY_KEY_WRITE' is enabled for a table, the key buffer is not
     flushed for the table on every index update, but only when the
     table is closed. This speeds up writes on keys a lot, but if you
     use this feature, you should add automatic checking of all
     `MyISAM' tables by starting the server with the `--myisam-recover'
     option (for example, `--myisam-recover=BACKUP,FORCE').  See *Note
     server-options::, and *Note myisam-start::.

     Note that if you enable external locking with
     `--external-locking', there is no protection against index
     corruption for tables that use delayed key writes.

   *  `delayed_insert_limit'

     *Command Line        `--delayed_insert_limit=#'
     Format*              
     *Config File Format* `delayed_insert_limit'
     *Option Sets         Yes, `delayed_insert_limit'
     Variable*            
     *Variable Name*      `delayed_insert_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default100           
     Range1-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default100           
     Range1-18446744073709547520

     After inserting `delayed_insert_limit' delayed rows, the *Note
     `INSERT DELAYED': insert-delayed.  handler thread checks whether
     there are any *Note `SELECT': select. statements pending. If so,
     it allows them to execute before continuing to insert delayed rows.

   *  `delayed_insert_timeout'

     *Command Line        `--delayed_insert_timeout=#'
     Format*              
     *Config File Format* `delayed_insert_timeout'
     *Option Sets         Yes, `delayed_insert_timeout'
     Variable*            
     *Variable Name*      `delayed_insert_timeout'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default300           

     How many seconds an *Note `INSERT DELAYED': insert-delayed.
     handler thread should wait for *Note `INSERT': insert. statements
     before terminating.

   *  `delayed_queue_size'

     *Command Line        `--delayed_queue_size=#'
     Format*              
     *Config File Format* `delayed_queue_size'
     *Option Sets         Yes, `delayed_queue_size'
     Variable*            
     *Variable Name*      `delayed_queue_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default1000          
     Range1-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default1000          
     Range1-18446744073709547520

     This is a per-table limit on the number of rows to queue when
     handling *Note `INSERT DELAYED': insert-delayed.  statements. If
     the queue becomes full, any client that issues an *Note `INSERT
     DELAYED': insert-delayed. statement waits until there is room in
     the queue again.

   *  `div_precision_increment'

     *Command Line        `--div_precision_increment=#'
     Format*              
     *Config File Format* `div_precision_increment'
     *Option Sets         Yes, `div_precision_increment'
     Variable*            
     *Variable Name*      `div_precision_increment'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default4 Range0-30   

     This variable indicates the number of digits by which to increase
     the scale of the result of division operations performed with the
     `/' operator.  The default value is 4. The minimum and maximum
     values are 0 and 30, respectively. The following example
     illustrates the effect of increasing the default value.

          mysql> SELECT 1/7;
          +--------+
          | 1/7    |
          +--------+
          | 0.1429 |
          +--------+
          mysql> SET div_precision_increment = 12;
          mysql> SELECT 1/7;
          +----------------+
          | 1/7            |
          +----------------+
          | 0.142857142857 |
          +----------------+

   *  `event_scheduler'

     *Command Line        `--event-scheduler[=value]'
     Format*              
     *Config File Format* `event-scheduler'
     *Option Sets         Yes, `event_scheduler'
     Variable*            
     *Variable Name*      `event_scheduler'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultOFF Valid     
     ValuesON, OFF,       
     DISABLED             

     This variable indicates the status of the Event Scheduler;
     possible values are `ON', `OFF', and `DISABLED', with the default
     being `OFF'. This variable and its effects on the Event
     Scheduler's operation are discussed in greater detail in the
     Overview section of the Events chapter.

   *  `expire_logs_days'

     *Command Line        `--expire_logs_days=#'
     Format*              
     *Config File Format* `expire_logs_days'
     *Option Sets         Yes, `expire_logs_days'
     Variable*            
     *Variable Name*      `expire_logs_days'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0 Range0-99   

     The number of days for automatic binary log removal. The default
     is 0, which means `no automatic removal.' Possible removals happen
     at startup and at binary log rotation.

   *  `flush'

     *Command Line        `--flush'
     Format*              
     *Config File Format* `flush'
     *Variable Name*      `flush'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     If `ON', the server flushes (synchronizes) all changes to disk
     after each SQL statement. Normally, MySQL does a write of all
     changes to disk only after each SQL statement and lets the
     operating system handle the synchronizing to disk. See *Note
     crashing::. This variable is set to `ON' if you start *Note
     `mysqld': mysqld. with the `--flush' option.

   *  `flush_time'

     *Command Line        `--flush_time=#'
     Format*              
     *Config File Format* `flush_time'
     *Option Sets         Yes, `flush_time'
     Variable*            
     *Variable Name*      `flush_time'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0 Min Value0  
     *Value Set *         
     Type                 
     (windows)numeric     
     Default1800 Min      
     Value0               

     If this is set to a non-zero value, all tables are closed every
     `flush_time' seconds to free up resources and synchronize
     unflushed data to disk. We recommend that this option be used only
     on Windows 9x or Me, or on systems with minimal resources.

   *  `ft_boolean_syntax'

     *Command Line        `--ft_boolean_syntax=name'
     Format*              
     *Config File Format* `ft_boolean_syntax'
     *Variable Name*      `ft_boolean_syntax'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           
     Default+-><()~*:""&  

     The list of operators supported by boolean full-text searches
     performed using `IN BOOLEAN MODE'. See *Note fulltext-boolean::.

     The default variable value is `'+ -><()~*:""&|''. The rules for
     changing the value are as follows:

        * Operator function is determined by position within the string.

        * The replacement value must be 14 characters.

        * Each character must be an ASCII non-alphanumeric character.

        * Either the first or second character must be a space.

        * No duplicates are allowed except the phrase quoting operators
          in positions 11 and 12. These two characters are not required
          to be the same, but they are the only two that may be.

        * Positions 10, 13, and 14 (which by default are set to ``:'',
          ``&'', and ``|'') are reserved for future extensions.

   *  `ft_max_word_len'

     *Command Line        `--ft_max_word_len=#'
     Format*              
     *Config File Format* `ft_max_word_len'
     *Option Sets         Yes, `ft_max_word_len'
     Variable*            
     *Variable Name*      `ft_max_word_len'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric Min      
     Value10              

     The maximum length of the word to be included in a `FULLTEXT'
     index.

     *Note*:

     `FULLTEXT' indexes must be rebuilt after changing this variable.
     Use `REPAIR TABLE TBL_NAME QUICK'.

   *  `ft_min_word_len'

     *Command Line        `--ft_min_word_len=#'
     Format*              
     *Config File Format* `ft_min_word_len'
     *Option Sets         Yes, `ft_min_word_len'
     Variable*            
     *Variable Name*      `ft_min_word_len'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default4 Min Value1  

     The minimum length of the word to be included in a `FULLTEXT'
     index.

     *Note*:

     `FULLTEXT' indexes must be rebuilt after changing this variable.
     Use `REPAIR TABLE TBL_NAME QUICK'.

   *  `ft_query_expansion_limit'

     *Command Line        `--ft_query_expansion_limit=#'
     Format*              
     *Config File Format* `ft_query_expansion_limit'
     *Option Sets         Yes, `ft_query_expansion_limit'
     Variable*            
     *Variable Name*      `ft_query_expansion_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default20            
     Range0-1000          

     The number of top matches to use for full-text searches performed
     using `WITH QUERY EXPANSION'.

   *  `ft_stopword_file'

     *Command Line        `--ft_stopword_file=name'
     Format*              
     *Config File Format* `ft_stopword_file'
     *Option Sets         Yes, `ft_stopword_file'
     Variable*            
     *Variable Name*      `ft_stopword_file'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The file from which to read the list of stopwords for full-text
     searches. All the words from the file are used; comments are _not_
     honored. By default, a built-in list of stopwords is used (as
     defined in the `storage/myisam/ft_static.c' file). Setting this
     variable to the empty string (`''') disables stopword filtering.

     *Note*:

     `FULLTEXT' indexes must be rebuilt after changing this variable or
     the contents of the stopword file.  Use `REPAIR TABLE TBL_NAME
     QUICK'.

   *  `general_log'

     *Command Line        `--general-log'
     Format*              
     *Config File Format* `general-log'
     *Option Sets         Yes, `general_log'
     Variable*            
     *Variable Name*      `general_log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Whether the general query log is enabled. The value can be 0 (or
     `OFF') to disable the log or 1 (or `ON') to enable the log. The
     default value depends on whether the `--general_log' option is
     given (`--log' before MySQL 6.0.8). The destination for log output
     is controlled by the `log_output' system variable; if that value
     is `NONE', no log entries are written even if the log is enabled.

   *  `general_log_file'

     *Command Line        `--general-log-file=file_name'
     Format*              
     *Config File Format* `general_log_file'
     *Option Sets         Yes, `general_log_file'
     Variable*            
     *Variable Name*      `general_log_file'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typefilename         
     Defaulthost_name.log 

     The name of the general query log file. The default value is
     `HOST_NAME.log', but the initial value can be changed with the
     `--general_log_file' option (`--log' before MySQL 6.0.8).

   *  `group_concat_max_len'

     *Command Line        `--group_concat_max_len=#'
     Format*              
     *Config File Format* `group_concat_max_len'
     *Option Sets         Yes, `group_concat_max_len'
     Variable*            
     *Variable Name*      `group_concat_max_len'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default1024          
     Range4-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default1024          
     Range4-18446744073709547520

     The maximum allowed result length in bytes for the
     `GROUP_CONCAT()' function. The default is 1024.

   *  `have_compress'

     `YES' if the `zlib' compression library is available to the server,
     `NO' if not. If not, the `COMPRESS()' and `UNCOMPRESS()' functions
     cannot be used.

   *  `have_crypt'

     `YES' if the `crypt()' system call is available to the server, `NO'
     if not. If not, the `ENCRYPT()' function cannot be used.

   *  `have_csv'

     `YES' if *Note `mysqld': mysqld. supports `ARCHIVE' tables, `NO' if
     not.

   *  `have_dynamic_loading'

     `YES' if *Note `mysqld': mysqld. supports dynamic loading of
     plugins, `NO' if not.

   *  `have_geometry'

     `YES' if the server supports spatial data types, `NO' if not.

   *  `have_innodb'

     `YES' if *Note `mysqld': mysqld. supports `InnoDB' tables.
     `DISABLED' if `--skip-innodb' is used.

   *  `have_openssl'

     This variable is an alias for `have_ssl'.

   *  `have_partitioning'

     `YES' if *Note `mysqld': mysqld. supports partitioning.

   *  `have_query_cache'

     `YES' if *Note `mysqld': mysqld. supports the query cache, `NO' if
     not.

   *  `have_rtree_keys'

     `YES' if `RTREE' indexes are available, `NO' if not. (These are
     used for spatial indexes in `MyISAM' tables.)

   *  `have_ssl'

     `YES' if *Note `mysqld': mysqld. supports SSL connections, `NO' if
     not.

   *  `have_symlink'

     `YES' if symbolic link support is enabled, `NO' if not. This is
     required on Unix for support of the `DATA DIRECTORY' and `INDEX
     DIRECTORY' table options, and on Windows for support of data
     directory symlinks.

   *  `hostname'

     *Variable Name*      `hostname'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     The server sets this variable to the server host name at startup.

   *  `init_connect'

     *Command Line        `--init-connect=name'
     Format*              
     *Config File Format* `init_connect'
     *Option Sets         Yes, `init_connect'
     Variable*            
     *Variable Name*      `init_connect'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     A string to be executed by the server for each client that
     connects. The string consists of one or more SQL statements.  To
     specify multiple statements, separate them by semicolon
     characters. For example, each client begins by default with
     autocommit mode enabled. There is no global system variable to
     specify that autocommit should be disabled by default, but
     `init_connect' can be used to achieve the same effect:

          SET GLOBAL init_connect='SET autocommit=0';

     This variable can also be set on the command line or in an option
     file. To set the variable as just shown using an option file,
     include these lines:

          [mysqld]
          init_connect='SET autocommit=0'

     Note that the content of `init_connect' is not executed for users
     that have the `SUPER' privilege. This is done so that an erroneous
     value for `init_connect' does not prevent all clients from
     connecting. For example, the value might contain a statement that
     has a syntax error, thus causing client connections to fail. Not
     executing `init_connect' for users that have the `SUPER' privilege
     enables them to open a connection and fix the `init_connect' value.

   *  `init_file'

     *Command Line        `--init-file=name'
     Format*              
     *Config File Format* `init-file'
     *Option Sets         Yes, `init_file'
     Variable*            
     *Variable Name*      `init_file'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The name of the file specified with the `--init-file' option when
     you start the server. This should be a file containing SQL
     statements that you want the server to execute when it starts.
     Each statement must be on a single line and should not include
     comments.

     Note that the `--init-file' option is unavailable if MySQL was
     configured with the `--disable-grant-options' option. See *Note
     configure-options::.

   * `innodb_XXX'

     `InnoDB' system variables are listed in *Note innodb-parameters::.

   *  `interactive_timeout'

     *Command Line        `--interactive_timeout=#'
     Format*              
     *Config File Format* `interactive_timeout'
     *Option Sets         Yes, `interactive_timeout'
     Variable*            
     *Variable Name*      `interactive_timeout'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default28800 Min     
     Value1               

     The number of seconds the server waits for activity on an
     interactive connection before closing it. An interactive client is
     defined as a client that uses the `CLIENT_INTERACTIVE' option to
     *Note `mysql_real_connect()': mysql-real-connect. See also
     `wait_timeout'.

   *  `join_buffer_size'

     *Command Line        `--join_buffer_size=#'
     Format*              
     *Config File Format* `join_buffer_size'
     *Option Sets         Yes, `join_buffer_size'
     Variable*            
     *Variable Name*      `join_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set (<=       
     6.0.8)*              
     Platform Bit Size64  
     Typenumeric          
     Default131072        
     Range8200-18446744073709547520
     *Value Set (>=       
     6.0.9)*              
     Platform Bit Size64  
     Typenumeric          
     Default131072        
     Range128-18446744073709547520

     The size of the buffer that is used for plain index scans, range
     index scans, and joins that do not use indexes and thus perform
     full table scans. Normally, the best way to get fast joins is to
     add indexes. Increase the value of `join_buffer_size' to get a
     faster full join when adding indexes is not possible. One join
     buffer is allocated for each full join between two tables. For a
     complex join between several tables for which indexes are not
     used, multiple join buffers might be necessary.

     The maximum allowable setting for `join_buffer_size' is 4GB. As of
     MySQL 5.2.6, values larger than 4GB are allowed for 64-bit
     platforms (except 64-bit Windows, for which large values are
     truncated to 4GB with a warning).

   *  `join_cache_level'

     *Version Introduced* 6.0.9
     *Command Line        `--join_cache_level=#'
     Format*              
     *Config File Format* `join_cache_level'
     *Option Sets         Yes, `join_cache_level'
     Variable*            
     *Variable Name*      `join_cache_level'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1 Range0-8    

     This variable is use for join buffer managment. It controls for
     which join operations of which types join buffers are supposed to
     be used. See *Note bnl-bka-optimization::. The allowable
     `join_cache_level' values are shown in the following table.

     *Option*   *Description*
     `0'        No join buffer is used for any join operation.
                This setting can be useful to for assessing
                baseline join performance in comparison to
                performance with non-zero values that enable
                use of join buffering.
     `1'        This is the default value. Join buffers are
                employed exactly in the same cases as in
                versions of MySQL prior to 6.0.9: They are
                used only for inner joins that are executed by
                the original Block Nested-Loop (BNL) join
                algorithm. When this algorithm is applied,
                rows of the inner table are accessed through a
                table scan, a plain index scan, or a range
                index scan.
     `2'        The server employs an incremental join buffer
                for a join operation if its first operand is
                produced by a join operation that uses a join
                buffer itself.
     `3'        The BNL algorithm is used for an outer join
                and semi-join operation with one inner table,
                and for inner joins.
     `4'        The BNL algorithm uses incremental buffers for
                inner tables. In this case, the BNL algorithm
                can be used for nested outer joins and
                semi-joins (outer joins and semi-joins with
                several inner tables). Such an operation can be
                executed only if incremental join buffers are
                used to join all inner tables but the first
                one.
     `5'        The BKA algorithm uses regular buffers for any
                join operation with index access to the joined
                table.
     `6'        The BKA algorithm uses incremental buffers for
                any join operation with index access to the
                joined table.
     `7'        The BKA algorithm uses regular join buffers
                with a hash table.
     `8'        The BKA algorithm uses incremental join
                buffers with a hash table.

     This variable was added in MySQL 6.0.9.

   *  `keep_files_on_create'

     *Command Line        `--keep_files_on_create=#'
     Format*              
     *Config File Format* `keep_files_on_create'
     *Option Sets         Yes, `keep_files_on_create'
     Variable*            
     *Variable Name*      `keep_files_on_create'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     If a `MyISAM' table is created with no `DATA DIRECTORY' option, the
     `.MYD' file is created in the database directory. By default, if
     `MyISAM' finds an existing `.MYD' file in this case, it overwrites
     it. The same applies to `.MYI' files for tables created with no
     `INDEX DIRECTORY' option. To suppress this behavior, set the
     `keep_files_on_create' variable to `ON' (1), in which case
     `MyISAM' will not overwrite existing files and returns an error
     instead. The default value is `OFF' (0).

     If a `MyISAM' table is created with a `DATA DIRECTORY' or `INDEX
     DIRECTORY' option and an existing `.MYD' or `.MYI' file is found,
     MyISAM always returns an error. It will not overwrite a file in
     the specified directory.

   *  `key_buffer_size'

     *Command Line        `--key_buffer_size=#'
     Format*              
     *Config File Format* `key_buffer_size'
     *Option Sets         Yes, `key_buffer_size'
     Variable*            
     *Variable Name*      `key_buffer_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default8388608       
     Range8-4294967295    

     Index blocks for `MyISAM' tables are buffered and are shared by
     all threads.  `key_buffer_size' is the size of the buffer used for
     index blocks. The key buffer is also known as the key cache.

     The maximum allowable setting for `key_buffer_size' is 4GB on
     32-bit platforms. Values larger than 4GB are allowed for 64-bit
     platforms. The effective maximum size might be less, depending on
     your available physical RAM and per-process RAM limits imposed by
     your operating system or hardware platform.  The value of this
     variable indicates the amount of memory requested. Internally, the
     server allocates as much memory as possible up to this amount, but
     the actual allocation might be less.

     Increase the value to get better index handling (for all reads and
     multiple writes) to as much as you can afford. Using a value that
     is 25% of total memory on a machine that mainly runs MySQL is
     quite common. However, if you make the value too large (for
     example, more than 50% of your total memory) your system might
     start to page and become extremely slow. MySQL relies on the
     operating system to perform file system caching for data reads, so
     you must leave some room for the file system cache. Consider also
     the memory requirements of other storage engines.

     For even more speed when writing many rows at the same time, use
     *Note `LOCK TABLES': lock-tables. See *Note insert-speed::.

     You can check the performance of the key buffer by issuing a *Note
     `SHOW STATUS': show-status. statement and examining the
     `Key_read_requests', `Key_reads', `Key_write_requests', and
     `Key_writes' status variables.  (See *Note show::.) The
     `Key_reads/Key_read_requests' ratio should normally be less than
     0.01. The `Key_writes/Key_write_requests' ratio is usually near 1
     if you are using mostly updates and deletes, but might be much
     smaller if you tend to do updates that affect many rows at the
     same time or if you are using the `DELAY_KEY_WRITE' table option.

     The fraction of the key buffer in use can be determined using
     `key_buffer_size' in conjunction with the `Key_blocks_unused'
     status variable and the buffer block size, which is available from
     the `key_cache_block_size' system variable:

          1 - ((Key_blocks_unused x key_cache_block_size) / key_buffer_size)

     This value is an approximation because some space in the key
     buffer may be allocated internally for administrative structures.

     It is possible to create multiple `MyISAM' key caches. The size
     limit of 4GB applies to each cache individually, not as a group.
     See *Note myisam-key-cache::.

   *  `key_cache_age_threshold'

     *Command Line        `--key_cache_age_threshold=#'
     Format*              
     *Config File Format* `key_cache_age_threshold'
     *Option Sets         Yes, `key_cache_age_threshold'
     Variable*            
     *Variable Name*      `key_cache_age_threshold'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default300           
     Range100-4294967295  
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default300           
     Range100-18446744073709547520

     This value controls the demotion of buffers from the hot sub-chain
     of a key cache to the warm sub-chain. Lower values cause demotion
     to happen more quickly. The minimum value is 100. The default
     value is 300. See *Note myisam-key-cache::.

   *  `key_cache_block_size'

     *Command Line        `--key_cache_block_size=#'
     Format*              
     *Config File Format* `key_cache_block_size'
     *Option Sets         Yes, `key_cache_block_size'
     Variable*            
     *Variable Name*      `key_cache_block_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1024          
     Range512-16384       

     The size in bytes of blocks in the key cache. The default value is
     1024. See *Note myisam-key-cache::.

   *  `key_cache_division_limit'

     *Command Line        `--key_cache_division_limit=#'
     Format*              
     *Config File Format* `key_cache_division_limit'
     *Option Sets         Yes, `key_cache_division_limit'
     Variable*            
     *Variable Name*      `key_cache_division_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default100           
     Range1-100           

     The division point between the hot and warm sub-chains of the key
     cache buffer chain. The value is the percentage of the buffer
     chain to use for the warm sub-chain. Allowable values range from 1
     to 100. The default value is 100. See *Note myisam-key-cache::.

   *  `language'

     *Command Line        `--language=name'
     Format*              
     *Config File Format* `language'
     *Option Sets         Yes, `language'
     Variable*            
     *Variable Name*      `language'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     Default/usr/local/mysql/share/mysql/english/

     The language used for error messages.

   *  `large_files_support'

     *Variable Name*      `large_files_support'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     Whether *Note `mysqld': mysqld. was compiled with options for
     large file support.

   *  `large_pages'

     *Command Line        `--large-pages'
     Format*              
     *Config File Format* `large-pages'
     *Option Sets         Yes, `large_pages'
     Variable*            
     *Variable Name*      `large_pages'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Platform Specific*  linux
     *Value Set *         
     Type (linux)boolean  
     DefaultFALSE         

     Whether large page support is enabled (via the `--large-pages'
     option). See *Note large-page-support::.

   *  `large_page_size'

     *Variable Name*      `large_page_size'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Type (linux)numeric  
     Default0             

     If large page support is enabled, this shows the size of memory
     pages. Currently, large memory pages are supported only on Linux;
     on other platforms, the value of this variable is always 0. See
     *Note large-page-support::.

   *  `lc_time_names'

     *Variable Name*      `lc_time_names'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     This variable specifies the locale that controls the language used
     to display day and month names and abbreviations. This variable
     affects the output from the `DATE_FORMAT()', `DAYNAME()' and
     `MONTHNAME()' functions. Locale names are POSIX-style values such
     as `'ja_JP'' or `'pt_BR''. The default value is `'en_US''
     regardless of your system's locale setting. For further
     information, see *Note locale-support::.

   *  `license'

     *Variable Name*      `license'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           
     DefaultGPL           

     The type of license the server has.

   *  `local_infile'

     *Variable Name*      `local_infile'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Type                 

     Whether `LOCAL' is supported for *Note `LOAD DATA INFILE':
     load-data. statements. See *Note load-data-local::.

   *  `locked_in_memory'

     *Variable Name*      `locked_in_memory'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     Whether *Note `mysqld': mysqld. was locked in memory with
     `--memlock'.

   *  `log'

     Whether logging of all statements to the general query log is
     enabled. See *Note query-log::.

     This variable is deprecated as of MySQL 6.0.8; use `general_log'
     instead.

   *  `log_bin'

     *Variable Name*      `log_bin'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     Whether the binary log is enabled. See *Note binary-log::.

   *  `log_bin_trust_function_creators'

     *Command Line        `--log-bin-trust-function-creators'
     Format*              
     *Config File Format* `log-bin-trust-function-creators'
     *Option Sets         Yes, `log_bin_trust_function_creators'
     Variable*            
     *Variable Name*      `log_bin_trust_function_creators'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     This variable applies when binary logging is enabled. It controls
     whether stored function creators can be trusted not to create
     stored functions that will cause unsafe events to be written to
     the binary log. If set to 0 (the default), users are not allowed
     to create or alter stored functions unless they have the `SUPER'
     privilege in addition to the `CREATE ROUTINE' or `ALTER ROUTINE'
     privilege. A setting of 0 also enforces the restriction that a
     function must be declared with the `DETERMINISTIC' characteristic,
     or with the `READS SQL DATA' or `NO SQL' characteristic. If the
     variable is set to 1, MySQL does not enforce these restrictions on
     stored function creation. This variable also applies to trigger
     creation. See *Note stored-programs-logging::.

   *  `log_error'

     *Command Line        `--log-error[=name]'
     Format*              
     *Config File Format* `log-error'
     *Option Sets         Yes, `log_error'
     Variable*            
     *Variable Name*      `log_error'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The location of the error log.

   *  `log_output'

     *Command Line        `--log-output[=name]'
     Format*              
     *Config File Format* `log-output'
     *Option Sets         Yes, `log_output'
     Variable*            
     *Variable Name*      `log_output'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultFILE Valid    
     ValuesTABLE, FILE,   
     NONE                 

     The destination for general query log and slow query log output.
     The value can be a comma-separated list of one or more of the
     words `TABLE' (log to tables), `FILE' (log to files), or `NONE'
     (do not log to tables or files). The default value is `TABLE'.
     `NONE', if present, takes precedence over any other specifiers. If
     the value is `NONE' log entries are not written even if the logs
     are enabled. If the logs are not enabled, no logging occurs even
     if the value of `log_output' is not `NONE'. For more information,
     see *Note log-tables::.

   *  `log_queries_not_using_indexes'

     *Command Line        `--log-queries-not-using-indexes'
     Format*              
     *Config File Format* `log-queries-not-using-indexes'
     *Option Sets         Yes, `log_queries_not_using_indexes'
     Variable*            
     *Variable Name*      `log_queries_not_using_indexes'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Deprecated*         5.1.29, by `slow-query-log'
     *Value Set *         
     Typeboolean          

     Whether queries that do not use indexes are logged to the slow
     query log. See *Note slow-query-log::.

   *  `log_slave_updates'

     Whether updates received by a slave server from a master server
     should be logged to the slave's own binary log. Binary logging
     must be enabled on the slave for this variable to have any effect.
     See *Note replication-options::.

   *  `log_slow_queries'

     *Command Line        `--log-slow-queries[=name]'
     Format*              
     *Config File Format* `log-slow-queries'
     *Option Sets         Yes, `log_slow_queries'
     Variable*            
     *Variable Name*      `log_slow_queries'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          

     Whether slow queries should be logged. `Slow' is determined by the
     value of the `long_query_time' variable. See *Note
     slow-query-log::.

     This variable is deprecated as of MySQL 6.0.8; use
     `slow_query_log' instead.

   *  `log_warnings'

     *Command Line        `--log-warnings[=#]'
     Format*              
     *Config File Format* `log-warnings'
     *Option Sets         Yes, `log_warnings'
     Variable*            
     *Variable Name*      `log_warnings'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Disabled by*        `skip-log-warnings'
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default1             
     Range0-18446744073709547520

     Whether to produce additional warning messages. It is enabled (1)
     by default and can be disabled by setting it to 0. Aborted
     connections are not logged to the error log unless the value is
     greater than 1.

   *  `long_query_time'

     *Command Line        `--long_query_time=#'
     Format*              
     *Config File Format* `long_query_time'
     *Option Sets         Yes, `long_query_time'
     Variable*            
     *Variable Name*      `long_query_time'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set (<=       
     6.0.3)*              
     Typenumeric          
     Default10 Min Value1 
     *Value Set (>=       
     6.0.4)*              
     Typenumeric          
     Default10 Min Value0 

     If a query takes longer than this many seconds, the server
     increments the `Slow_queries' status variable. If the slow query
     log is enabled, the query is logged to the slow query log file.
     This value is measured in real time, not CPU time, so a query that
     is under the threshold on a lightly loaded system might be above
     the threshold on a heavily loaded one. Prior to MySQL 6.0.4, the
     minimum value is 1, and the value for this variable must be an
     integer. Beginning with MySQL 6.0.4, the minimum is 0, and a
     resolution of microseconds is supported when logging to a file.
     However, the microseconds part is ignored and only integer values
     are written when logging to tables. The default value is 10. See
     *Note slow-query-log::.

   *  `low_priority_updates'

     *Command Line        `--low-priority-updates'
     Format*              
     *Config File Format* `low-priority-updates'
     *Option Sets         Yes, `low_priority_updates'
     Variable*            
     *Variable Name*      `low_priority_updates'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     If set to `1', all *Note `INSERT': insert, *Note `UPDATE': update,
     *Note `DELETE': delete, and `LOCK TABLE WRITE' statements wait
     until there is no pending *Note `SELECT': select. or `LOCK TABLE
     READ' on the affected table. This affects only storage engines
     that use only table-level locking (`MyISAM', `MEMORY', `MERGE').
     This variable previously was named `sql_low_priority_updates'.

   *  `lower_case_file_system'

     *Command Line        `--lower_case_file_system[=#]'
     Format*              
     *Config File Format* `lower_case_file_system'
     *Option Sets         Yes, `lower_case_file_system'
     Variable*            
     *Variable Name*      `lower_case_file_system'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeboolean          

     This variable describes the case sensitivity of file names on the
     file system where the data directory is located.  `OFF' means file
     names are case sensitive, `ON' means they are not case sensitive.

   *  `lower_case_table_names'

     *Command Line        `--lower_case_table_names[=#]'
     Format*              
     *Config File Format* `lower_case_table_names'
     *Option Sets         Yes, `lower_case_table_names'
     Variable*            
     *Variable Name*      `lower_case_table_names'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default0 Range0-2    

     If set to 1, table names are stored in lowercase on disk and table
     name comparisons are not case sensitive. If set to 2 table names
     are stored as given but compared in lowercase.  This option also
     applies to database names and table aliases.  See *Note
     identifier-case-sensitivity::.

     If you are using `InnoDB' tables, you should set this variable to
     1 on all platforms to force names to be converted to lowercase.

     You should _not_ set this variable to 0 if you are running MySQL
     on a system that does not have case-sensitive file names (such as
     Windows or Mac OS X). If this variable is not set at startup and
     the file system on which the data directory is located does not
     have case-sensitive file names, MySQL automatically sets
     `lower_case_table_names' to 2.

   *  `max_allowed_packet'

     *Command Line        `--max_allowed_packet=#'
     Format*              
     *Config File Format* `max_allowed_packet'
     *Option Sets         Yes, `max_allowed_packet'
     Variable*            
     *Variable Name*      `max_allowed_packet'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1048576       
     Range1024-1073741824 

     The maximum size of one packet or any generated/intermediate
     string.

     The packet message buffer is initialized to `net_buffer_length'
     bytes, but can grow up to `max_allowed_packet' bytes when needed.
     This value by default is small, to catch large (possibly
     incorrect) packets.

     You must increase this value if you are using large *Note `BLOB':
     blob. columns or long strings.  It should be as big as the largest
     *Note `BLOB': blob. you want to use. The protocol limit for
     `max_allowed_packet' is 1GB.  The value should be a multiple of
     1024; non-multiples are rounded down to the nearest multiple.

     When you change the message buffer size by changing the value of
     the `max_allowed_packet' variable, you should also change the
     buffer size on the client side if your client program allows it.
     On the client side, `max_allowed_packet' has a default of 1GB.
     Some programs such as *Note `mysql': mysql.  and *Note
     `mysqldump': mysqldump. enable you to change the client-side value
     by setting `max_allowed_packet' on the command line or in an
     option file.

     As of MySQL 6.0.9, the session value of this variable is read
     only. Before 6.0.9, setting the session value is allowed but has
     no effect.

   *  `max_connect_errors'

     *Command Line        `--max_connect_errors=#'
     Format*              
     *Config File Format* `max_connect_errors'
     *Option Sets         Yes, `max_connect_errors'
     Variable*            
     *Variable Name*      `max_connect_errors'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default10            
     Range1-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default10            
     Range1-18446744073709547520

     If there are more than this number of interrupted connections from
     a host, that host is blocked from further connections.  You can
     unblock blocked hosts with the *Note `FLUSH HOSTS': flush.
     statement.

   *  `max_connections'

     *Command Line        `--max_connections=#'
     Format*              
     *Config File Format* `max_connections'
     *Option Sets         Yes, `max_connections'
     Variable*            
     *Variable Name*      `max_connections'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default151           
     Range1-100000        

     The number of simultaneous client connections allowed. By default,
     this is 151. See *Note too-many-connections::, for more
     information.

     MySQL Enterprise

     For notification that the maximum number of connections is getting
     dangerously high and for advice on setting the optimum value for
     `max_connections' subscribe to the MySQL Enterprise Monitor. For
     more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

     Increasing this value increases the number of file descriptors
     that *Note `mysqld': mysqld. requires. See *Note table-cache::,
     for comments on file descriptor limits.

   *  `max_delayed_threads'

     *Command Line        `--max_delayed_threads=#'
     Format*              
     *Config File Format* `max_delayed_threads'
     *Option Sets         Yes, `max_delayed_threads'
     Variable*            
     *Variable Name*      `max_delayed_threads'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default20            
     Range0-16384         

     Do not start more than this number of threads to handle *Note
     `INSERT DELAYED': insert-delayed. statements. If you try to insert
     data into a new table after all *Note `INSERT DELAYED':
     insert-delayed. threads are in use, the row is inserted as if the
     `DELAYED' attribute wasn't specified. If you set this to 0, MySQL
     never creates a thread to handle `DELAYED' rows; in effect, this
     disables `DELAYED' entirely.

     For the `SESSION' value of this variable, the only valid values
     are 0 or the `GLOBAL' value.

   *  `max_error_count'

     *Command Line        `--max_error_count=#'
     Format*              
     *Config File Format* `max_error_count'
     *Option Sets         Yes, `max_error_count'
     Variable*            
     *Variable Name*      `max_error_count'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default64            
     Range0-65535         

     The maximum number of error, warning, and note messages to be
     stored for display by the *Note `SHOW ERRORS': show-errors. and
     *Note `SHOW WARNINGS': show-warnings. statements.

   *  `max_heap_table_size'

     *Command Line        `--max_heap_table_size=#'
     Format*              
     *Config File Format* `max_heap_table_size'
     *Option Sets         Yes, `max_heap_table_size'
     Variable*            
     *Variable Name*      `max_heap_table_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default16777216      
     Range16384-4294967295

     This variable sets the maximum size to which `MEMORY' tables are
     allowed to grow. The value of the variable is used to calculate
     `MEMORY' table `MAX_ROWS' values. Setting this variable has no
     effect on any existing `MEMORY' table, unless the table is
     re-created with a statement such as *Note `CREATE TABLE':
     create-table. or altered with *Note `ALTER TABLE': alter-table. or
     *Note `TRUNCATE TABLE': truncate. A server restart also sets the
     maximum size of existing `MEMORY' tables to the global
     `max_heap_table_size' value.

     *Note*:

     On 64-bit platforms, the maximum value for this variable is
     1844674407370954752.

     MySQL Enterprise

     Subscribers to the MySQL Enterprise Monitor receive
     recommendations for the optimum setting for `max_heap_table_size'.
     For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `max_insert_delayed_threads'

     *Variable Name*      `max_insert_delayed_threads'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          

     This variable is a synonym for `max_delayed_threads'.

   *  `max_join_size'

     *Command Line        `--max_join_size=#'
     Format*              
     *Config File Format* `max_join_size'
     *Option Sets         Yes, `max_join_size'
     Variable*            
     *Variable Name*      `max_join_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default4294967295    
     Range1-4294967295    

     Do not allow *Note `SELECT': select. statements that probably need
     to examine more than `max_join_size' rows (for single-table
     statements) or row combinations (for multiple-table statements) or
     that are likely to do more than `max_join_size' disk seeks. By
     setting this value, you can catch *Note `SELECT': select.
     statements where keys are not used properly and that would
     probably take a long time. Set it if your users tend to perform
     joins that lack a `WHERE' clause, that take a long time, or that
     return millions of rows.

     Setting this variable to a value other than `DEFAULT' resets the
     value of `sql_big_selects' to `0'. If you set the
     `sql_big_selects' value again, the `max_join_size' variable is
     ignored.

     If a query result is in the query cache, no result size check is
     performed, because the result has previously been computed and it
     does not burden the server to send it to the client.

     This variable previously was named `sql_max_join_size'.

   *  `max_length_for_sort_data'

     *Command Line        `--max_length_for_sort_data=#'
     Format*              
     *Config File Format* `max_length_for_sort_data'
     *Option Sets         Yes, `max_length_for_sort_data'
     Variable*            
     *Variable Name*      `max_length_for_sort_data'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1024          
     Range4-8388608       

     The cutoff on the size of index values that determines which
     `filesort' algorithm to use. See *Note order-by-optimization::.

   *  `max_prepared_stmt_count'

     *Command Line        `--max_prepared_stmt_count=#'
     Format*              
     *Config File Format* `max_prepared_stmt_count'
     *Option Sets         Yes, `max_prepared_stmt_count'
     Variable*            
     *Variable Name*      `max_prepared_stmt_count'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default16382         
     Range0-1048576       

     This variable limits the total number of prepared statements in
     the server. It can be used in environments where there is the
     potential for denial-of-service attacks based on running the
     server out of memory by preparing huge numbers of statements. If
     the value is set lower than the current number of prepared
     statements, existing statements are not affected and can be used,
     but no new statements can be prepared until the current number
     drops below the limit. The default value is 16,382. The allowable
     range of values is from 0 to 1 million.  Setting the value to 0
     disables prepared statements.

   *  `max_relay_log_size'

     *Command Line        `--max_relay_log_size=#'
     Format*              
     *Config File Format* `max_relay_log_size'
     *Option Sets         Yes, `max_relay_log_size'
     Variable*            
     *Variable Name*      `max_relay_log_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-1073741824    

     If a write by a replication slave to its relay log causes the
     current log file size to exceed the value of this variable, the
     slave rotates the relay logs (closes the current file and opens
     the next one). If `max_relay_log_size' is 0, the server uses
     `max_binlog_size' for both the binary log and the relay log. If
     `max_relay_log_size' is greater than 0, it constrains the size of
     the relay log, which enables you to have different sizes for the
     two logs. You must set `max_relay_log_size' to between 4096 bytes
     and 1GB (inclusive), or to 0. The default value is 0. See *Note
     replication-implementation-details::.

   *  `max_seeks_for_key'

     *Command Line        `--max_seeks_for_key=#'
     Format*              
     *Config File Format* `max_seeks_for_key'
     *Option Sets         Yes, `max_seeks_for_key'
     Variable*            
     *Variable Name*      `max_seeks_for_key'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default4294967295    
     Range1-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default18446744073709547520
     Range1-18446744073709547520

     Limit the assumed maximum number of seeks when looking up rows
     based on a key. The MySQL optimizer assumes that no more than this
     number of key seeks are required when searching for matching rows
     in a table by scanning an index, regardless of the actual
     cardinality of the index (see *Note show-index::). By setting this
     to a low value (say, 100), you can force MySQL to prefer indexes
     instead of table scans.

   *  `max_sort_length'

     *Command Line        `--max_sort_length=#'
     Format*              
     *Config File Format* `max_sort_length'
     *Option Sets         Yes, `max_sort_length'
     Variable*            
     *Variable Name*      `max_sort_length'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1024          
     Range4-8388608       

     The number of bytes to use when sorting *Note `BLOB': blob. or
     *Note `TEXT': blob. values. Only the first `max_sort_length' bytes
     of each value are used; the rest are ignored.

   *  `max_sp_recursion_depth'

     *Command Line        `--max_sp_recursion_depth[=#]'
     Format*              
     *Config File Format* `max_sp_recursion_depth'
     *Option Sets         Yes, `max_sp_recursion_depth'
     Variable*            
     *Variable Name*      `max_sp_recursion_depth'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0 Max         
     Value255             

     The number of times that any given stored procedure may be called
     recursively. The default value for this option is 0, which
     completely disallows recursion in stored procedures. The maximum
     value is 255.

     Stored procedure recursion increases the demand on thread stack
     space. If you increase the value of `max_sp_recursion_depth', it
     may be necessary to increase thread stack size by increasing the
     value of `thread_stack' at server startup.

   *  `max_tmp_tables'

     *Command Line        `--max_tmp_tables=#'
     Format*              
     *Config File Format* `max_tmp_tables'
     *Option Sets         Yes, `max_tmp_tables'
     Variable*            
     *Variable Name*      `max_tmp_tables'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default32            
     Range1-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default32            
     Range1-18446744073709547520

     The maximum number of temporary tables a client can keep open at
     the same time. (This option does not yet do anything.)

   *  `max_user_connections'

     *Command Line        `--max_user_connections=#'
     Format*              
     *Config File Format* `max_user_connections'
     *Option Sets         Yes, `max_user_connections'
     Variable*            
     *Variable Name*      `max_user_connections'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Range1-4294967295    

     The maximum number of simultaneous connections allowed to any
     given MySQL account. A value of 0 means `no limit.'

     This variable has both a global scope and a (read-only) session
     scope. The session variable has the same value as the global
     variable unless the current account has a non-zero
     `MAX_USER_CONNECTIONS' resource limit. In that case, the session
     value reflects the account limit.

   *  `max_write_lock_count'

     *Command Line        `--max_write_lock_count=#'
     Format*              
     *Config File Format* `max_write_lock_count'
     *Option Sets         Yes, `max_write_lock_count'
     Variable*            
     *Variable Name*      `max_write_lock_count'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default4294967295    
     Range1-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default18446744073709547520
     Range1-18446744073709547520

     After this many write locks, allow some pending read lock requests
     to be processed in between.

   *  `min_examined_row_limit'

     *Version Introduced* 6.0.4
     *Command Line        `--min-examined-row-limit=#'
     Format*              
     *Config File Format* `min-examined-row-limit'
     *Variable Name*      `min_examined_row_limit'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default0             
     Range0-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default0             
     Range0-18446744073709547520

     Queries that examine fewer than this number of rows are not logged
     to the slow query log. This variable was added in MySQL 6.0.4.

   *  `myisam_data_pointer_size'

     *Command Line        `--myisam_data_pointer_size=#'
     Format*              
     *Config File Format* `myisam_data_pointer_size'
     *Option Sets         Yes, `myisam_data_pointer_size'
     Variable*            
     *Variable Name*      `myisam_data_pointer_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default6 Range2-7    

     The default pointer size in bytes, to be used by *Note `CREATE
     TABLE': create-table. for `MyISAM' tables when no `MAX_ROWS'
     option is specified. This variable cannot be less than 2 or larger
     than 7. The default value is 6. See *Note full-table::.

   *  `myisam_max_sort_file_size'

     *Command Line        `--myisam_max_sort_file_size=#'
     Format*              
     *Config File Format* `myisam_max_sort_file_size'
     *Option Sets         Yes, `myisam_max_sort_file_size'
     Variable*            
     *Variable Name*      `myisam_max_sort_file_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default2147483648    

     The maximum size of the temporary file that MySQL is allowed to
     use while re-creating a `MyISAM' index (during *Note `REPAIR
     TABLE': repair-table, *Note `ALTER TABLE': alter-table, or *Note
     `LOAD DATA INFILE': load-data.). If the file size would be larger
     than this value, the index is created using the key cache instead,
     which is slower. The value is given in bytes.

     The default value is 2GB. If `MyISAM' index files exceed this size
     and disk space is available, increasing the value may help
     performance.

   *  `myisam_recover_options'

     *Variable Name*      `myisam_recover_options'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     The value of the `--myisam-recover' option. See *Note
     server-options::.

   *  `myisam_repair_threads'

     *Command Line        `--myisam_repair_threads=#'
     Format*              
     *Config File Format* `myisam_repair_threads'
     *Option Sets         Yes, `myisam_repair_threads'
     Variable*            
     *Variable Name*      `myisam_repair_threads'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default1             
     Range1-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default1             
     Range1-18446744073709547520

     If this value is greater than 1, `MyISAM' table indexes are
     created in parallel (each index in its own thread) during the
     `Repair by sorting' process. The default value is 1.

     *Note*:

     Multi-threaded repair is still _beta-quality_ code.

   *  `myisam_sort_buffer_size'

     *Command Line        `--myisam_sort_buffer_size=#'
     Format*              
     *Config File Format* `myisam_sort_buffer_size'
     *Option Sets         Yes, `myisam_sort_buffer_size'
     Variable*            
     *Variable Name*      `myisam_sort_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default8388608       
     Range4-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default8388608       
     Range4-18446744073709547520

     The size of the buffer that is allocated when sorting `MyISAM'
     indexes during a *Note `REPAIR TABLE': repair-table. or when
     creating indexes with *Note `CREATE INDEX': create-index. or *Note
     `ALTER TABLE': alter-table.

     The maximum allowable setting for `myisam_sort_buffer_size' is
     4GB. Values larger than 4GB are allowed for 64-bit platforms
     (except 64-bit Windows, for which large values are truncated to
     4GB with a warning).

   *  `myisam_stats_method'

     *Command Line        `--myisam_stats_method=name'
     Format*              
     *Config File Format* `myisam_stats_method'
     *Option Sets         Yes, `myisam_stats_method'
     Variable*            
     *Variable Name*      `myisam_stats_method'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     Valid                
     Valuesnulls_equal,   
     nulls_unequal,       
     nulls_ignored        

     How the server treats `NULL' values when collecting statistics
     about the distribution of index values for `MyISAM' tables. This
     variable has three possible values, `nulls_equal',
     `nulls_unequal', and `nulls_ignored'. For `nulls_equal', all `NULL'
     index values are considered equal and form a single value group
     that has a size equal to the number of `NULL' values. For
     `nulls_unequal', `NULL' values are considered unequal, and each
     `NULL' forms a distinct value group of size 1. For `nulls_ignored',
     `NULL' values are ignored.

     The method that is used for generating table statistics influences
     how the optimizer chooses indexes for query execution, as
     described in *Note myisam-index-statistics::.

     Any unique prefix of a valid value may be used to set the value of
     this variable.

   *  `myisam_use_mmap'

     *Command Line        `--myisam_use_mmap'
     Format*              
     *Config File Format* `myisam_use_mmap'
     *Option Sets         Yes, `myisam_use_mmap'
     Variable*            
     *Variable Name*      `myisam_use_mmap'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Use memory mapping for reading and writing `MyISAM' tables.

   *  `named_pipe'

     *Variable Name*      `named_pipe'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Platform Specific*  windows

     (Windows only.) Indicates whether the server supports connections
     over named pipes.

   *  `net_buffer_length'

     *Command Line        `--net_buffer_length=#'
     Format*              
     *Config File Format* `net_buffer_length'
     *Option Sets         Yes, `net_buffer_length'
     Variable*            
     *Variable Name*      `net_buffer_length'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default16384         
     Range1024-1048576    

     Each client thread is associated with a connection buffer and
     result buffer. Both begin with a size given by `net_buffer_length'
     but are dynamically enlarged up to `max_allowed_packet' bytes as
     needed. The result buffer shrinks to `net_buffer_length' after each
     SQL statement.

     This variable should not normally be changed, but if you have very
     little memory, you can set it to the expected length of statements
     sent by clients. If statements exceed this length, the connection
     buffer is automatically enlarged. The maximum value to which
     `net_buffer_length' can be set is 1MB.

     As of MySQL 6.0.9, the session value of this variable is read
     only. Before 6.0.9, setting the session value is allowed but has
     no effect.

   *  `net_read_timeout'

     *Command Line        `--net_read_timeout=#'
     Format*              
     *Config File Format* `net_read_timeout'
     *Option Sets         Yes, `net_read_timeout'
     Variable*            
     *Variable Name*      `net_read_timeout'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default30 Min Value1 

     The number of seconds to wait for more data from a connection
     before aborting the read. This timeout applies only to TCP/IP
     connections, not to connections made via Unix socket files, named
     pipes, or shared memory. When the server is reading from the
     client, `net_read_timeout' is the timeout value controlling when
     to abort. When the server is writing to the client,
     `net_write_timeout' is the timeout value controlling when to
     abort. See also `slave_net_timeout'
     (http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_net_timeout).

   *  `net_retry_count'

     *Command Line        `--net_retry_count=#'
     Format*              
     *Config File Format* `net_retry_count'
     *Option Sets         Yes, `net_retry_count'
     Variable*            
     *Variable Name*      `net_retry_count'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default10            
     Range1-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default10            
     Range1-18446744073709547520

     If a read on a communication port is interrupted, retry this many
     times before giving up. This value should be set quite high on
     FreeBSD because internal interrupts are sent to all threads.

   *  `net_write_timeout'

     *Command Line        `--net_write_timeout=#'
     Format*              
     *Config File Format* `net_write_timeout'
     *Option Sets         Yes, `net_write_timeout'
     Variable*            
     *Variable Name*      `net_write_timeout'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default60 Min Value1 

     The number of seconds to wait for a block to be written to a
     connection before aborting the write. This timeout applies only to
     TCP/IP connections, not to connections made via Unix socket files,
     named pipes, or shared memory. See also `net_read_timeout'.

   *  `new'

     *Command Line        `--new'
     Format*              
     *Config File Format* `new'
     *Option Sets         Yes, `new'
     Variable*            
     *Variable Name*      `new'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Disabled by*        `skip-new'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     This variable was used in MySQL 4.0 to turn on some 4.1 behaviors,
     and is retained for backward compatibility. In MySQL 6.0, its
     value is always `OFF'.

   *  `old'

     *Command Line        `old'
     Format*              
     *Config File Format* `old'
     *Variable Name*      `old'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     `old' is a compatibility variable. It is disabled by default, but
     can be enabled at startup to revert the server to behaviors
     present in older versions.

     Currently, when `old' is enabled, it changes the default scope of
     index hints to that used prior to MySQL 5.1.17. That is, index
     hints with no `FOR' clause apply only to how indexes are used for
     row retrieval and not to resolution of `ORDER BY' or `GROUP BY'
     clauses. (See *Note index-hints::.) Take care about enabling this
     in a replication setup. With statement-based binary logging,
     having different modes for the master and slaves might lead to
     replication errors.

   *  `old_passwords'

     *Command Line        `--old_passwords'
     Format*              
     *Config File Format* `old-passwords'
     *Option Sets         Yes, `old_passwords'
     Variable*            
     *Variable Name*      `old_passwords'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Whether the server should use pre-4.1-style passwords for MySQL
     user accounts. See *Note old-client::.

   *  `one_shot'

     This is not a variable, but it can be used when setting some
     variables. It is described in *Note set-option::.

   *  `open_files_limit'

     *Command Line        `--open-files-limit=#'
     Format*              
     *Config File Format* `open-files-limit'
     *Option Sets         Yes, `open_files_limit'
     Variable*            
     *Variable Name*      `open_files_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-65535         

     The number of files that the operating system allows *Note
     `mysqld': mysqld. to open. This is the real value allowed by the
     system and might be different from the value you gave using the
     `--open-files-limit' option to *Note `mysqld': mysqld. or *Note
     `mysqld_safe': mysqld-safe.  The value is 0 on systems where MySQL
     can't change the number of open files.

   *  `optimizer_prune_level'

     *Command Line        `--optimizer_prune_level[=#]'
     Format*              
     *Config File Format* `optimizer_prune_level'
     *Option Sets         Yes, `optimizer_prune_level'
     Variable*            
     *Variable Name*      `optimizer_prune_level'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean Default1 

     Controls the heuristics applied during query optimization to prune
     less-promising partial plans from the optimizer search space. A
     value of 0 disables heuristics so that the optimizer performs an
     exhaustive search. A value of 1 causes the optimizer to prune
     plans based on the number of rows retrieved by intermediate plans.

   *  `optimizer_search_depth'

     *Command Line        `--optimizer_search_depth[=#]'
     Format*              
     *Config File Format* `optimizer_search_depth'
     *Option Sets         Yes, `optimizer_search_depth'
     Variable*            
     *Variable Name*      `optimizer_search_depth'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default62            

     The maximum depth of search performed by the query optimizer.
     Values larger than the number of relations in a query result in
     better query plans, but take longer to generate an execution plan
     for a query. Values smaller than the number of relations in a
     query return an execution plan quicker, but the resulting plan may
     be far from being optimal. If set to 0, the system automatically
     picks a reasonable value. If set to the maximum number of tables
     used in a query plus 2, the optimizer switches to the algorithm
     used in MySQL 5.0.0 (and previous versions) for performing
     searches.

   *  `optimizer_switch'

     *Command Line        `--optimizer_switch=value'
     Format*              
     *Config File Format* `optimizer_switch'
     *Option Sets         Yes, `optimizer_switch'
     Variable*            
     *Variable Name*      `optimizer_switch'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set (<=       
     6.0.11)*             
     Typeenumeration      
     Default" Valid       
     Valuesno_semijoin,   
     no_materialization,  
     no_loosescan,        
     no_firstmatch        
     *Value Set (>=       
     6.0.11)*             
     Typeenumeration      
     Valid                
     Valuesindex_merge,   
     index_merge_intersection,
     index_merge_union,   
     semijoin,            
     materialization,     
     loosescan,           
     firstmatch           

     The `optimizer_switch' system variable enables control over
     individual optimizations. As of MySQL 6.0.11, the value of this
     variable is a set of flags, each of which has a value of `on' or
     `off' to indicate whether the corresponding optimization is
     enabled or disabled. This variable has global and session values
     and be changed at runtime. The global default can be set at server
     startup.

     To see the current set of optimizer values, select the variable
     value:

          mysql> SELECT @@optimizer_switch\G
          *************************** 1. row ***************************
          @@optimizer_switch: firstmatch=on,index_merge=on,index_merge_union=on,
                              index_merge_sort_union=on,index_merge_intersection=on,
                              loosescan=on,materialization=on,semijoin=on
          1 row in set (0.00 sec)

     For more information about the syntax of this variable and the set
     of optimizations that it controls, see *Note
     switchable-optimizations::.

     Prior to MySQL 6.1.11, the syntax of `optimizer_switch' is like
     that of an *Note `ENUM': enum. column or the `sql_mode' system
     variable. The value can be set to a comma-separated list of flags
     to disable specific optimizations, chosen from `no_semijoin'
     (disable semi-join), `no_materialization' (disable
     materialization), `no_loosescan' (disable LooseScan, available as
     of MySQL 6.0.7), and `no_firstmatch' (disable FirstMatch,
     available as of MySQL 6.0.10). For example:

          SET @optimizer_switch='no_semijoin,no_materialization';

     Presence or absence of a `no_OPT_NAME' keyword means that its
     optimization is disabled or enabled, respectively. The default
     value is the empty string (no optimizations disabled).

   *  `optimizer_use_mrr'

     *Variable Name*      `optimizer_use_mrr'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     Defaultforce Valid   
     Valuesauto,          
     disable, force       

     Controls whether the optimizer uses the Multi-Range Read (MRR)
     access method for which a number of ranges are sent to a storage
     engine at once during range selects. Sending multiple ranges to a
     handler at once can improve the performance of certain selects
     dramatically.

     The value can be `'force'' (use MRR when possible; this is the
     default), `'disable'' (do not use MRR), or `'auto''. (attempt to
     make a cost-based choice between using and not using MRR).

     Any unique prefix of a valid value may be used to set the value of
     this variable.

     The optimizer interface provided by this variable is tentative.
     (For example, at the moment, the cost formula is such that we do
     not recommend a setting of `'auto''. It is better to use `'force''
     or `'disable''.)  Currently, this variable enables use of MRR to
     be turned on or off, but the syntax might change to allow control
     over additional capabilities.

     The `optimizer_use_mrr' system variable replaces the
     `multi_range_count' variable from older versions of MySQL.

   *  `pid_file'

     *Command Line        `--pid-file=name'
     Format*              
     *Config File Format* `pid-file'
     *Option Sets         Yes, `pid_file'
     Variable*            
     *Variable Name*      `pid_file'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path name of the process ID (PID) file. This variable can be
     set with the `--pid-file' option.

   *  `plugin_dir'

     *Command Line        `--plugin_dir=name'
     Format*              
     *Config File Format* `plugin_dir'
     *Option Sets         Yes, `plugin_dir'
     Variable*            
     *Variable Name*      `plugin_dir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     Default/usr/local/mysql/lib/mysql

     The path name of the plugin directory.

   *  `port'

     *Command Line        `--port=#'
     Format*              
     *Config File Format* `port'
     *Option Sets         Yes, `port'
     Variable*            
     *Variable Name*      `port'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default3306          

     The number of the port on which the server listens for TCP/IP
     connections. This variable can be set with the `--port' option.

   *  `preload_buffer_size'

     *Command Line        `--preload_buffer_size=#'
     Format*              
     *Config File Format* `preload_buffer_size'
     *Option Sets         Yes, `preload_buffer_size'
     Variable*            
     *Variable Name*      `preload_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default32768         
     Range1024-1073741824 

     The size of the buffer that is allocated when preloading indexes.

   *  `protocol_version'

     *Variable Name*      `protocol_version'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          

     The version of the client/server protocol used by the MySQL server.

   *  `query_alloc_block_size'

     *Command Line        `--query_alloc_block_size=#'
     Format*              
     *Config File Format* `query_alloc_block_size'
     *Option Sets         Yes, `query_alloc_block_size'
     Variable*            
     *Variable Name*      `query_alloc_block_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default8192          
     Range1024-4294967295 
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default8192          
     Range1024-18446744073709547520

     The allocation size of memory blocks that are allocated for
     objects created during statement parsing and execution. If you
     have problems with memory fragmentation, it might help to increase
     this a bit.

   *  `query_cache_limit'

     *Command Line        `--query_cache_limit=#'
     Format*              
     *Config File Format* `query_cache_limit'
     *Option Sets         Yes, `query_cache_limit'
     Variable*            
     *Variable Name*      `query_cache_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default1048576       
     Range0-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default1048576       
     Range0-18446744073709547520

     Don't cache results that are larger than this number of bytes.
     The default value is 1MB.

   *  `query_cache_min_res_unit'

     *Command Line        `--query_cache_min_res_unit=#'
     Format*              
     *Config File Format* `query_cache_min_res_unit'
     *Option Sets         Yes, `query_cache_min_res_unit'
     Variable*            
     *Variable Name*      `query_cache_min_res_unit'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default4096          
     Range512-4294967295  
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default4096          
     Range512-18446744073709547520

     The minimum size (in bytes) for blocks allocated by the query
     cache. The default value is 4096 (4KB). Tuning information for
     this variable is given in *Note query-cache-configuration::.

   *  `query_cache_size'

     *Command Line        `--query_cache_size=#'
     Format*              
     *Config File Format* `query_cache_size'
     *Option Sets         Yes, `query_cache_size'
     Variable*            
     *Variable Name*      `query_cache_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default0             
     Range0-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default0             
     Range0-18446744073709547520

     The amount of memory allocated for caching query results. The
     default value is 0, which disables the query cache. The allowable
     values are multiples of 1024; other values are rounded down to the
     nearest multiple. Note that `query_cache_size' bytes of memory are
     allocated even if `query_cache_type' is set to 0.  See *Note
     query-cache-configuration::, for more information.

     The query cache needs a minimum size of about 40KB to allocate its
     structures. (The exact size depends on system architecture.) If
     you set the value of `query_cache_size' too small, you'll get a
     warning, as described in *Note query-cache-configuration::.

   *  `query_cache_type'

     *Command Line        `--query_cache_type=#'
     Format*              
     *Config File Format* `query_cache_type'
     *Option Sets         Yes, `query_cache_type'
     Variable*            
     *Variable Name*      `query_cache_type'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     Default1 Valid       
     Values0, 1, 2        

     Set the query cache type. Setting the `GLOBAL' value sets the type
     for all clients that connect thereafter. Individual clients can
     set the `SESSION' value to affect their own use of the query
     cache. Possible values are shown in the following table.

     *Option*   *Description*
     `0' or     Don't cache results in or retrieve results
     `OFF'      from the query cache. Note that this does not
                deallocate the query cache buffer.  To do
                that, you should set `query_cache_size' to 0.
     `1' or     Cache all cacheable query results except for
     `ON'       those that begin with `SELECT SQL_NO_CACHE'.
     `2' or     Cache results only for cacheable queries that
     `DEMAND'   begin with `SELECT SQL_CACHE'.

     This variable defaults to `ON'.

     Any unique prefix of a valid value may be used to set the value of
     this variable.

   *  `query_cache_wlock_invalidate'

     *Command Line        `--query_cache_wlock_invalidate'
     Format*              
     *Config File Format* `query_cache_wlock_invalidate'
     *Option Sets         Yes, `query_cache_wlock_invalidate'
     Variable*            
     *Variable Name*      `query_cache_wlock_invalidate'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Normally, when one client acquires a `WRITE' lock on a `MyISAM'
     table, other clients are not blocked from issuing statements that
     read from the table if the query results are present in the query
     cache. Setting this variable to 1 causes acquisition of a `WRITE'
     lock for a table to invalidate any queries in the query cache that
     refer to the table. This forces other clients that attempt to
     access the table to wait while the lock is in effect.

   *  `query_prealloc_size'

     *Command Line        `--query_prealloc_size=#'
     Format*              
     *Config File Format* `query_prealloc_size'
     *Option Sets         Yes, `query_prealloc_size'
     Variable*            
     *Variable Name*      `query_prealloc_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default8192          
     Range8192-4294967295 
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default8192          
     Range8192-18446744073709547520

     The size of the persistent buffer used for statement parsing and
     execution. This buffer is not freed between statements. If you are
     running complex queries, a larger `query_prealloc_size' value
     might be helpful in improving performance, because it can reduce
     the need for the server to perform memory allocation during query
     execution operations.

   *  `range_alloc_block_size'

     *Command Line        `--range_alloc_block_size=#'
     Format*              
     *Config File Format* `range_alloc_block_size'
     *Option Sets         Yes, `range_alloc_block_size'
     Variable*            
     *Variable Name*      `range_alloc_block_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default4096          
     Range4096-18446744073709547520

     The size of blocks that are allocated when doing range
     optimization.

   *  `read_buffer_size'

     *Command Line        `--read_buffer_size=#'
     Format*              
     *Config File Format* `read_buffer_size'
     *Option Sets         Yes, `read_buffer_size'
     Variable*            
     *Variable Name*      `read_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default131072        
     Range8200-2147479552 

     Each thread that does a sequential scan allocates a buffer of this
     size (in bytes) for each table it scans. If you do many sequential
     scans, you might want to increase this value, which defaults to
     131072. The value of this variable should be a multiple of 4KB. If
     it is set to a value that is not a multiple of 4KB, its value will
     be rounded down to the nearest multiple of 4KB.

     The maximum allowable setting for `read_buffer_size' is 2GB.

     `read_buffer_size' and `read_rnd_buffer_size' are not specific to
     any storage engine and apply in a general manner for optimization.
     See *Note memory-use::, for example.

   *  `read_only'

     *Command Line        `--read_only'
     Format*              
     *Config File Format* `read_only'
     *Option Sets         Yes, `read_only'
     Variable*            
     *Variable Name*      `read_only'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric Default0 

     This variable is off by default. When it is enabled, the server
     allows no updates except from users that have the `SUPER'
     privilege or (on a slave server) from updates performed by slave
     threads. On a slave server, this can be useful to ensure that the
     slave accepts updates only from its master server and not from
     clients. This variable does not apply to `TEMPORARY' tables, nor
     does it prevent the server from inserting rows into the log tables
     (see *Note log-tables::).

     `read_only' exists only as a `GLOBAL' variable, so changes to its
     value require the `SUPER' privilege.  Changes to `read_only' on a
     master server are not replicated to slave servers. The value can
     be set on a slave server independent of the setting on the master.

     The following conditions apply:

        * If you attempt to enable `read_only' while you have any
          explicit locks (acquired with *Note `LOCK TABLES':
          lock-tables.) or have a pending transaction, an error occurs.

        * If you attempt to enable `read_only' while other clients hold
          explicit table locks or have pending transactions, the
          attempt blocks until the locks are released and the
          transactions end. While the attempt to enable `read_only' is
          pending, requests by other clients for table locks or to
          begin transactions also block until `read_only' has been set.

        * `read_only' can be enabled while you hold a global read lock
          (acquired with *Note `FLUSH TABLES WITH READ LOCK': flush.)
          because that does not involve table locks.

     As of MySQL 6.0.11, attempts to set `read_only' block for active
     transactions that hold metadata locks until those transactions end.

   *  `read_rnd_buffer_size'

     *Command Line        `--read_rnd_buffer_size=#'
     Format*              
     *Config File Format* `read_rnd_buffer_size'
     *Option Sets         Yes, `read_rnd_buffer_size'
     Variable*            
     *Variable Name*      `read_rnd_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default262144        
     Range8200-4294967295 

     When reading rows in sorted order following a key-sorting
     operation, the rows are read through this buffer to avoid disk
     seeks. See *Note order-by-optimization::. Setting the variable to
     a large value can improve `ORDER BY' performance by a lot.
     However, this is a buffer allocated for each client, so you should
     not set the global variable to a large value. Instead, change the
     session variable only from within those clients that need to run
     large queries.

     The maximum allowable setting for `read_rnd_buffer_size' is 2GB.

     `read_buffer_size' and `read_rnd_buffer_size' are not specific to
     any storage engine and apply in a general manner for optimization.
     See *Note memory-use::, for example.

   *  `relay_log_purge'

     *Command Line        `--relay_log_purge'
     Format*              
     *Config File Format* `relay_log_purge'
     *Option Sets         Yes, `relay_log_purge'
     Variable*            
     *Variable Name*      `relay_log_purge'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     Disables or enables automatic purging of relay log files as soon
     as they are not needed any more. The default value is 1 (`ON').

   *  `relay_log_space_limit'

     *Command Line        `--relay_log_space_limit=#'
     Format*              
     *Config File Format* `relay_log_space_limit'
     *Option Sets         Yes, `relay_log_space_limit'
     Variable*            
     *Variable Name*      `relay_log_space_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default0             
     Range0-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default0             
     Range0-18446744073709547520

     The maximum amount of space to use for all relay logs.

   *  `report_host'

     The value of the `--report-host' option. This variable was added
     in MySQL 6.0.5.

   *  `report_password'

     The value of the `--report-password' option. This variable was
     added in MySQL 6.0.5.

   *  `report_port'

     The value of the `--report-port' option. This variable was added
     in MySQL 6.0.5.

   *  `report_user'

     The value of the `--report-user' option. This variable was added
     in MySQL 6.0.5.

   *  `rpl_semi_sync_master_enabled'

     Controls whether semisynchronous replication is enabled on the
     master. To enable or disable the plugin, set this variable to 1 or
     0, respectively. The default is 1.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `rpl_semi_sync_master_reply_log_file_pos'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `rpl_semi_sync_master_timeout'

     A value in seconds that controls how long the master waits on a
     commit for acknowledgment from a slave before timing out and
     reverting to asynchronous replication. The default value is 10
     seconds.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `rpl_semi_sync_master_trace_level'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `rpl_semi_sync_slave_enabled'

     Controls whether semisynchronous replication is enabled on the
     slave. To enable or disable the plugin, set this variable to 1 or
     0, respectively. The default is 1.

     This variable is was added in MySQL 6.0.8. It is available only if
     the slave-side semisynchronous replication plugin is installed.

   *  `rpl_semi_sync_slave_trace_level'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the slave-side semisynchronous replication plugin is installed.

   *  `secure_auth'

     *Command Line        `--secure-auth'
     Format*              
     *Config File Format* `secure-auth'
     *Option Sets         Yes, `secure_auth'
     Variable*            
     *Variable Name*      `secure_auth'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     If the MySQL server has been started with the `--secure-auth'
     option, it blocks connections from all accounts that have
     passwords stored in the old (pre-4.1) format. In that case, the
     value of this variable is `ON', otherwise it is `OFF'.

     You should enable this option if you want to prevent all use of
     passwords employing the old format (and hence insecure
     communication over the network).

     Server startup fails with an error if this option is enabled and
     the privilege tables are in pre-4.1 format. See *Note old-client::.

   *  `secure_backup_file_priv'

     By default, this variable is empty. If set to the name of a
     directory, it limits the effect of the *Note `BACKUP DATABASE':
     backup-database. and *Note `RESTORE': restore. statements to work
     only with files in that directory. This variable was added in MySQL
     6.0.11; in older releases, use `secure_backup_file_priv' instead.

   *  `secure_file_priv'

     *Command Line        `--secure-file-priv'
     Format*              
     *Config File Format* `secure-file-priv'
     *Option Sets         Yes, `secure_file_priv'
     Variable*            
     *Variable Name*      `secure_file_priv'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     By default, this variable is empty. If set to the name of a
     directory, it limits the effect of the `LOAD_FILE()' function and
     the *Note `LOAD DATA': load-data. and *Note `SELECT ... INTO
     OUTFILE': select. statements to work only with files in that
     directory. Before MySQL 6.0.11, it also applies to the *Note
     `BACKUP DATABASE': backup-database. and *Note `RESTORE': restore.
     statements; as of 6.0.11, `secure_backup_file_priv' applies to
     those statements.

   *  `server_id'

     *Command Line        `--server-id=#'
     Format*              
     *Config File Format* `server-id'
     *Option Sets         Yes, `server_id'
     Variable*            
     *Variable Name*      `server_id'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-4294967295    

     The server ID, used in replication to give each master and slave a
     unique identity. This variable is set by the `--server-id' option.
     For each server participating in replication, you should pick a
     positive integer in the range from 1 to 2^32 - 1 to act as that
     server's ID.

   *  `shared_memory'

     *Variable Name*      `shared_memory'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Platform Specific*  windows

     (Windows only.) Whether the server allows shared-memory
     connections.

   *  `shared_memory_base_name'

     *Variable Name*      `shared_memory_base_name'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Platform Specific*  windows

     (Windows only.) The name of shared memory to use for shared-memory
     connections. This is useful when running multiple MySQL instances
     on a single physical machine. The default name is `MYSQL'. The
     name is case sensitive.

   *  `skip_external_locking'

     This is `OFF' if *Note `mysqld': mysqld.  uses external locking,
     `ON' if external locking is disabled.

   *  `skip_networking'

     This is `ON' if the server allows only local (non-TCP/IP)
     connections. On Unix, local connections use a Unix socket file. On
     Windows, local connections use a named pipe or shared memory. On
     NetWare, only TCP/IP connections are supported, so do not set this
     variable to `ON'. This variable can be set to `ON' with the
     `--skip-networking' option.

   *  `skip_show_database'

     This prevents people from using the *Note `SHOW DATABASES':
     show-databases. statement if they do not have the `SHOW DATABASES'
     privilege. This can improve security if you have concerns about
     users being able to see databases belonging to other users. Its
     effect depends on the `SHOW DATABASES' privilege: If the variable
     value is `ON', the *Note `SHOW DATABASES': show-databases.
     statement is allowed only to users who have the `SHOW DATABASES'
     privilege, and the statement displays all database names. If the
     value is `OFF', *Note `SHOW DATABASES': show-databases. is allowed
     to all users, but displays the names of only those databases for
     which the user has the `SHOW DATABASES' or other privilege.

   *  `slow_launch_time'

     *Command Line        `--slow_launch_time=#'
     Format*              
     *Config File Format* `slow_launch_time'
     *Option Sets         Yes, `slow_launch_time'
     Variable*            
     *Variable Name*      `slow_launch_time'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric Default2 

     If creating a thread takes longer than this many seconds, the
     server increments the `Slow_launch_threads' status variable.

   *  `slow_query_log'

     Whether the slow query log is enabled. The value can be 0 (or
     `OFF') to disable the log or 1 (or `ON') to enable the log. The
     default value depends on whether the `--slow_query_log' option is
     given (`--log-slow-queries' before MySQL 6.0.8). The destination
     for log output is controlled by the `log_output' system variable;
     if that value is `NONE', no log entries are written even if the
     log is enabled.

   *  `slow_query_log_file'

     *Command Line        `--slow-query-log-file=file_name'
     Format*              
     *Config File Format* `slow_query_log_file'
     *Option Sets         Yes, `slow_query_log_file'
     Variable*            
     *Variable Name*      `slow_query_log_file'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typefilename         

     The name of the slow query log file. The default value is
     `HOST_NAME-slow.log', but the initial value can be changed with the
     `--slow_query_log_file' option (`--log-slow-queries' before MySQL
     6.0.8).

   *  `socket'

     *Command Line        `--socket=name'
     Format*              
     *Config File Format* `socket'
     *Option Sets         Yes, `socket'
     Variable*            
     *Variable Name*      `socket'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     Default/tmp/mysql.sock

     On Unix platforms, this variable is the name of the socket file
     that is used for local client connections. The default is
     `/tmp/mysql.sock'. (For some distribution formats, the directory
     might be different, such as `/var/lib/mysql' for RPMs.)

     On Windows, this variable is the name of the named pipe that is
     used for local client connections. The default value is `MySQL'
     (not case sensitive).

   *  `sort_buffer_size'

     *Command Line        `--sort_buffer_size=#'
     Format*              
     *Config File Format* `sort_buffer_size'
     *Option Sets         Yes, `sort_buffer_size'
     Variable*            
     *Variable Name*      `sort_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default2097144 Max   
     Value4294967295      
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default2097144 Max   
     Value18446744073709547520

     Each thread that needs to do a sort allocates a buffer of this
     size. Increase this value for faster `ORDER BY' or `GROUP BY'
     operations. See *Note temporary-files::.

     The maximum allowable setting for `sort_buffer_size' is 4GB. As of
     MySQL 5.2.6, values larger than 4GB are allowed for 64-bit
     platforms (except 64-bit Windows, for which large values are
     truncated to 4GB with a warning).

   *  `sql_mode'

     *Command Line        `--sql-mode=name'
     Format*              
     *Config File Format* `sql-mode'
     *Option Sets         Yes, `sql_mode'
     Variable*            
     *Variable Name*      `sql_mode'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeset Default"     
     Valid                
     ValuesALLOW_INVALID_DATES,
     ANSI_QUOTES,         
     ERROR_FOR_DIVISION_BY_ZERO,
     HIGH_NOT_PRECEDENCE, 
     IGNORE_SPACE,        
     NO_AUTO_CREATE_USER, 
     NO_AUTO_VALUE_ON_ZERO,
     NO_BACKSLASH_ESCAPES,
     NO_DIR_IN_CREATE,    
     NO_ENGINE_SUBSTITUTION,
     NO_FIELD_OPTIONS,    
     NO_KEY_OPTIONS,      
     NO_TABLE_OPTIONS,    
     NO_UNSIGNED_SUBTRACTION,
     NO_ZERO_DATE,        
     NO_ZERO_IN_DATE,     
     ONLY_FULL_GROUP_BY,  
     PAD_CHAR_TO_FULL_LENGTH,
     PIPES_AS_CONCAT,     
     REAL_AS_FLOAT,       
     STRICT_ALL_TABLES,   
     STRICT_TRANS_TABLES  

     The current server SQL mode, which can be set dynamically. See
     *Note server-sql-mode::.

   *  `sql_select_limit'

     *Variable Name*      `sql_select_limit'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          

     The maximum number of rows to return from *Note `SELECT': select.
     statements. The default value for a new connection is the maximum
     number of rows that the server allows per table, which depends on
     the server configuration and may be affected if the server build
     was configured with `--with-big-tables'. Typical default values
     are (2^32)-1 or (2^64)-1. If you have changed the limit, the
     default value can be restored by assigning a value of `DEFAULT'.

     If a *Note `SELECT': select. has a `LIMIT' clause, the `LIMIT'
     takes precedence over the value of `sql_select_limit'.

     `sql_select_limit' does not apply to *Note `SELECT': select.
     statements executed within stored routines. It also does not apply
     to *Note `SELECT': select. statements that do not produce a result
     set to be returned to the client. These include *Note `SELECT':
     select. statements in subqueries, `CREATE TABLE ... SELECT', and
     `INSERT INTO ... SELECT'.

   *  `ssl_ca'

     *Command Line        `--ssl-ca=name'
     Format*              
     *Config File Format* `ssl-ca'
     *Option Sets         Yes, `ssl_ca'
     Variable*            
     *Variable Name*      `ssl_ca'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path to a file with a list of trusted SSL CAs.

   *  `ssl_capath'

     *Command Line        `--ssl-capath=name'
     Format*              
     *Config File Format* `ssl-capath'
     *Option Sets         Yes, `ssl_capath'
     Variable*            
     *Variable Name*      `ssl_capath'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path to a directory that contains trusted SSL CA certificates
     in PEM format.

   *  `ssl_cert'

     *Command Line        `--ssl-cert=name'
     Format*              
     *Config File Format* `ssl-cert'
     *Option Sets         Yes, `ssl_cert'
     Variable*            
     *Variable Name*      `ssl_cert'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The name of the SSL certificate file to use for establishing a
     secure connection.

   *  `ssl_cipher'

     *Command Line        `--ssl-cipher=name'
     Format*              
     *Config File Format* `ssl-cipher'
     *Option Sets         Yes, `ssl_cipher'
     Variable*            
     *Variable Name*      `ssl_cipher'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     A list of allowable ciphers to use for SSL encryption.

   *  `ssl_key'

     *Command Line        `--ssl-key=name'
     Format*              
     *Config File Format* `ssl-key'
     *Option Sets         Yes, `ssl_key'
     Variable*            
     *Variable Name*      `ssl_key'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     The name of the SSL key file to use for establishing a secure
     connection.

   *  `storage_engine'

     *Variable Name*      `storage_engine'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      

     The default storage engine (table type). To set the storage engine
     at server startup, use the `--default-storage-engine' option. See
     *Note server-options::.

   *  `sync_frm'

     *Command Line        `--sync-frm'
     Format*              
     *Config File Format* `sync-frm'
     *Option Sets         Yes, `sync_frm'
     Variable*            
     *Variable Name*      `sync_frm'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     If this variable is set to 1, when any non-temporary table is
     created its `.frm' file is synchronized to disk (using
     `fdatasync()'). This is slower but safer in case of a crash. The
     default is 1.

   *  `system_time_zone'

     *Variable Name*      `system_time_zone'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     The server system time zone. When the server begins executing, it
     inherits a time zone setting from the machine defaults, possibly
     modified by the environment of the account used for running the
     server or the startup script. The value is used to set
     `system_time_zone'.  Typically the time zone is specified by the
     `TZ' environment variable. It also can be specified using the
     `--timezone' option of the *Note `mysqld_safe': mysqld-safe.
     script.

     The `system_time_zone' variable differs from `time_zone'.
     Although they might have the same value, the latter variable is
     used to initialize the time zone for each client that connects.
     See *Note time-zone-support::.

   *  `table_definition_cache'

     *Command Line        `--table_definition_cache=#'
     Format*              
     *Config File Format* `table_definition_cache'
     *Option Sets         Yes, `table_definition_cache'
     Variable*            
     *Variable Name*      `table_definition_cache'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set (<=       
     6.0.6)*              
     Typenumeric          
     Default128           
     Range1-524288        
     *Value Set (>=       
     6.0.6)*              
     Typenumeric          
     Default256           
     Range256-524288      

     The number of table definitions that can be stored in the
     definition cache. If you use a large number of tables, you can
     create a large table definition cache to speed up opening of
     tables. The table definition cache takes less space and does not
     use file descriptors, unlike the normal table cache. The minimum
     and default values are 1 and 128 before MySQL 6.0.6.  The minimum
     and default are both 256 as of MySQL 6.0.6.

   *  `table_lock_wait_timeout'

     *Command Line        `--table_lock_wait_timeout=#'
     Format*              
     *Config File Format* `table_lock_wait_timeout'
     *Option Sets         Yes, `table_lock_wait_timeout'
     Variable*            
     *Variable Name*      `table_lock_wait_timeout'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default50            
     Range1-1073741824    

     This variable currently is unused.

   *  `table_open_cache'

     *Command Line        `--table-open-cache=#'
     Format*              
     *Config File Format* `table_open_cache'
     *Variable Name*      `table_open_cache'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default64            
     Range1-524288        

     The number of open tables for all threads. Increasing this value
     increases the number of file descriptors that *Note `mysqld':
     mysqld. requires. You can check whether you need to increase the
     table cache by checking the `Opened_tables' status variable. See
     *Note server-status-variables::. If the value of `Opened_tables'
     is large and you don't do *Note `FLUSH TABLES': flush.  often
     (which just forces all tables to be closed and reopened), then you
     should increase the value of the `table_open_cache' variable.  For
     more information about the table cache, see *Note table-cache::.

   *  `thread_cache_size'

     *Command Line        `--thread_cache_size=#'
     Format*              
     *Config File Format* `thread_cache_size'
     *Option Sets         Yes, `thread_cache_size'
     Variable*            
     *Variable Name*      `thread_cache_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-16384         

     How many threads the server should cache for reuse. When a client
     disconnects, the client's threads are put in the cache if there
     are fewer than `thread_cache_size' threads there. Requests for
     threads are satisfied by reusing threads taken from the cache if
     possible, and only when the cache is empty is a new thread
     created. This variable can be increased to improve performance if
     you have a lot of new connections.  (Normally, this doesn't
     provide a notable performance improvement if you have a good
     thread implementation.) By examining the difference between the
     `Connections' and `Threads_created' status variables, you can see
     how efficient the thread cache is. For details, see *Note
     server-status-variables::.

   *  `thread_concurrency'

     *Command Line        `--thread_concurrency=#'
     Format*              
     *Config File Format* `thread_concurrency'
     *Option Sets         Yes, `thread_concurrency'
     Variable*            
     *Variable Name*      `thread_concurrency'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default10 Range1-512 

     This variable is specific to Solaris systems, for which *Note
     `mysqld': mysqld. invokes the `thr_setconcurrency()' with the
     variable value. This function enables applications to give the
     threads system a hint about the desired number of threads that
     should be run at the same time.

   *  `thread_handling'

     *Command Line        `--thread_handling=name'
     Format*              
     *Config File Format* `thread_handling'
     *Option Sets         Yes, `thread_handling'
     Variable*            
     *Variable Name*      `thread_handling'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set (<=       
     6.0.4)*              
     Typeenumeration      
     Valid                
     Valuesno-threads,    
     one-thread-per-connection
     *Value Set (>=       
     6.0.4)*              
     Typeenumeration      
     Valid                
     Valuesno-threads,    
     one-thread-per-connection,
     pool-of-threads      

     The thread-handling model. The allowable values are `no-threads'
     (the server uses one thread), `one-thread-per-connection' (the
     server uses one thread to handle each client connection),
     `pool-of-threads' (the server does not create a thread per client
     connection, but uses a pool of threads for processing statements).
     `no-threads' is useful for debugging under Linux; see MySQL
     Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).
     `pool-of-threads' is available as of MySQL 6.0.4. To use thread
     pooling, MySQL must be configured with the `--with-libevent'
     option when you run `configure'.

     For information about choosing one thread model over the other and
     tuning the parameters that control thread resources, see *Note
     connection-threads::.

   *  `thread_pool_size'

     *Version Introduced* 6.0.4
     *Command Line        `--thread_pool_size=#'
     Format*              
     *Config File Format* `thread_pool_size'
     *Option Sets         Yes, `thread_pool_size'
     Variable*            
     *Variable Name*      `thread_pool_size'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default20            
     Range1-16384         

     The size of the thread pool that is use if `thread_handling' is
     set to `pool-of-threads'. The default pool size is 20, and the
     range of values is 1 to 16,384. This variable was added in MySQL
     6.0.4.

   *  `thread_stack'

     *Command Line        `--thread_stack=#'
     Format*              
     *Config File Format* `thread_stack'
     *Option Sets         Yes, `thread_stack'
     Variable*            
     *Variable Name*      `thread_stack'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default196608        
     Range131072-4294967295
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default196608        
     Range131072-18446744073709547520

     The stack size for each thread. Many of the limits detected by the
     `crash-me' test are dependent on this value. See *Note
     mysql-benchmarks::. The default (192KB) is large enough for normal
     operation. If the thread stack size is too small, it limits the
     complexity of the SQL statements that the server can handle, the
     recursion depth of stored procedures, and other memory-consuming
     actions.

   *  `time_format'

     This variable is unused.

   *  `time_zone'

     *Command Line        `--default_time_zone=string'
     Format*              
     *Config File Format* `default_time_zone'
     *Variable Name*      `time_zone'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The current time zone. This variable is used to initialize the
     time zone for each client that connects. By default, the initial
     value of this is `'SYSTEM'' (which means, `use the value of
     `system_time_zone'').  The value can be specified explicitly at
     server startup with the `--default-time-zone' option.  See *Note
     time-zone-support::.

   *  `timed_mutexes'

     *Command Line        `--timed_mutexes'
     Format*              
     *Config File Format* `timed_mutexes'
     *Option Sets         Yes, `timed_mutexes'
     Variable*            
     *Variable Name*      `timed_mutexes'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     This variable controls whether `InnoDB' mutexes are timed. If this
     variable is set to 0 or `OFF' (the default), mutex timing is
     disabled. If the variable is set to 1 or `ON', mutex timing is
     enabled. With timing enabled, the `os_wait_times' value in the
     output from *Note `SHOW ENGINE INNODB MUTEX': show-engine.
     indicates the amount of time (in ms) spent in operating system
     waits. Otherwise, the value is 0.

   *  `tmp_table_size'

     *Command Line        `--tmp_table_size=#'
     Format*              
     *Config File Format* `tmp_table_size'
     *Option Sets         Yes, `tmp_table_size'
     Variable*            
     *Variable Name*      `tmp_table_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Defaultsystem        
     dependent            
     Range1024-4294967295 

     The maximum size of internal in-memory temporary tables. (The
     actual limit is determined as the smaller of `max_heap_table_size'
     and `tmp_table_size'.) If an in-memory temporary table exceeds the
     limit, MySQL automatically converts it to an on-disk `MyISAM'
     table. Increase the value of `tmp_table_size' (and
     `max_heap_table_size' if necessary) if you do many advanced `GROUP
     BY' queries and you have lots of memory. This variable does not
     apply to user-created `MEMORY' tables.

   *  `tmpdir'

     *Command Line        `--tmpdir=name'
     Format*              
     *Config File Format* `tmpdir'
     *Option Sets         Yes, `tmpdir'
     Variable*            
     *Variable Name*      `tmpdir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The directory used for temporary files and temporary tables.  This
     variable can be set to a list of several paths that are used in
     round-robin fashion. Paths should be separated by colon characters
     (``:'') on Unix and semicolon characters (``;'') on Windows,
     NetWare, and OS/2.

     The multiple-directory feature can be used to spread the load
     between several physical disks. If the MySQL server is acting as a
     replication slave, you should not set `tmpdir' to point to a
     directory on a memory-based file system or to a directory that is
     cleared when the server host restarts. A replication slave needs
     some of its temporary files to survive a machine restart so that it
     can replicate temporary tables or *Note `LOAD DATA INFILE':
     load-data. operations. If files in the temporary file directory
     are lost when the server restarts, replication fails. However, if
     you are using MySQL 4.0.0 or later, you can set the slave's
     temporary directory using the `slave_load_tmpdir' variable.  In
     that case, the slave won't use the general `tmpdir' value and you
     can set `tmpdir' to a non-permanent location.

   *  `transaction_alloc_block_size'

     *Command Line        `--transaction_alloc_block_size=#'
     Format*              
     *Config File Format* `transaction_alloc_block_size'
     *Option Sets         Yes, `transaction_alloc_block_size'
     Variable*            
     *Variable Name*      `transaction_alloc_block_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default8192          
     Range1024-4294967295 

     The amount in bytes by which to increase a per-transaction memory
     pool which needs memory. See the description of
     `transaction_prealloc_size'.

   *  `transaction_prealloc_size'

     *Command Line        `--transaction_prealloc_size=#'
     Format*              
     *Config File Format* `transaction_prealloc_size'
     *Option Sets         Yes, `transaction_prealloc_size'
     Variable*            
     *Variable Name*      `transaction_prealloc_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default4096          
     Range1024-4294967295 
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default4096          
     Range1024-18446744073709547520

     There is a per-transaction memory pool from which various
     transaction-related allocations take memory. The initial size of
     the pool in bytes is `transaction_prealloc_size'.  For every
     allocation that cannot be satisfied from the pool because it has
     insufficient memory available, the pool is increased by
     `transaction_alloc_block_size' bytes. When the transaction ends,
     the pool is truncated to `transaction_prealloc_size' bytes.

     By making `transaction_prealloc_size' sufficiently large to
     contain all statements within a single transaction, you can avoid
     many `malloc()' calls.

   *  `tx_isolation'

     *Variable Name*      `tx_isolation'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultREPEATABLE-READ
     Valid                
     ValuesREAD-UNCOMMITTED,
     READ-COMMITTED,      
     REPEATABLE-READ,     
     SERIALIZABLE         

     The default transaction isolation level. Defaults to
     `REPEATABLE-READ'.

     This variable is set by the *Note `SET TRANSACTION ISOLATION
     LEVEL': set-transaction. statement. See *Note set-transaction::.
     If you set `tx_isolation' directly to an isolation level name that
     contains a space, the name should be enclosed within quotes, with
     the space replaced by a dash. For example:

          SET tx_isolation = 'READ-COMMITTED';

   *  `updatable_views_with_limit'

     *Command Line        `--updatable_views_with_limit=#'
     Format*              
     *Config File Format* `updatable_views_with_limit'
     *Option Sets         Yes, `updatable_views_with_limit'
     Variable*            
     *Variable Name*      `updatable_views_with_limit'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean Default1 

     This variable controls whether updates to a view can be made when
     the view does not contain all columns of the primary key defined
     in the underlying table, if the update statement contains a
     `LIMIT' clause. (Such updates often are generated by GUI tools.)
     An update is an *Note `UPDATE': update. or *Note `DELETE': delete.
     statement. Primary key here means a `PRIMARY KEY', or a `UNIQUE'
     index in which no column can contain `NULL'.

     The variable can have two values:

        * `1' or `YES': Issue a warning only (not an error message).
          This is the default value.

        * `0' or `NO': Prohibit the update.

   * `version'

     *Command Line        `--version'
     Format*              
     *Config File Format* `version'
     *Variable Name*      `version'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     The version number for the server.

   *  `version_comment'

     The `configure' script has a `--with-comment' option that allows a
     comment to be specified when building MySQL. This variable contains
     the value of that comment.

   *  `version_compile_machine'

     The type of machine or architecture on which MySQL was built.

   *  `version_compile_os'

     *Variable Name*      `version_compile_os'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     The type of operating system on which MySQL was built.

   *  `wait_timeout'

     *Command Line        `--wait_timeout=#'
     Format*              
     *Config File Format* `wait_timeout'
     *Option Sets         Yes, `wait_timeout'
     Variable*            
     *Variable Name*      `wait_timeout'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default28800         
     Range1-31536000      
     *Value Set *         
     Type                 
     (windows)numeric     
     Default28800         
     Range1-2147483       

     The number of seconds the server waits for activity on a
     non-interactive connection before closing it. This timeout applies
     only to TCP/IP and Unix socket file connections, not to
     connections made via named pipes, or shared memory.

     On thread startup, the session `wait_timeout' value is initialized
     from the global `wait_timeout' value or from the global
     `interactive_timeout' value, depending on the type of client (as
     defined by the `CLIENT_INTERACTIVE' connect option to *Note
     `mysql_real_connect()': mysql-real-connect.). See also
     `interactive_timeout'.

MySQL Enterprise

Expert use of server system variables is part of the service offered by
the MySQL Enterprise Monitor. To subscribe, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: server-session-variables,  Next: using-system-variables,  Prev: server-system-variables,  Up: mysqld-server

5.1.4 Session System Variables
------------------------------

Several system variables exist only as session variables. These cannot
be set at server startup but can be assigned values at runtime using the
*Note `SET': set-option.  statement (except for those that are read
only). Most of them are not displayed by *Note `SHOW VARIABLES':
show-variables, but you can obtain their values using *Note `SELECT':
select. This section describes the session system variables. For
information about setting or displaying their values, see *Note
using-system-variables::. For example:

     mysql> SELECT @@autocommit;
     +--------------+
     | @@autocommit |
     +--------------+
     |            1 |
     +--------------+

The lettercase of these variables does not matter.

The following table lists the system variables that have only session
scope:

*`mysqld' Session System Variable Summary*

*Name*                        *Cmd-Line**Option   *System   *Dynamic*
                                        file*     Var*      
autocommit                                        Yes       Yes
backup_wait_timeout                               Yes       Yes
big-tables                    Yes       Yes                 
- _Variable_: big_tables                          Yes       Yes
error_count                                       Yes       No
foreign_key_checks                                Yes       Yes
identity                                          Yes       Yes
insert_id                                         Yes       Yes
last_insert_id                                    Yes       Yes
profiling                                         Yes       Yes
rand_seed1                                        Yes       Yes
rand_seed2                                        Yes       Yes
sql_auto_is_null                                  Yes       Yes
sql_big_selects                                   Yes       Yes
sql_big_tables                                    Yes       Yes
sql_buffer_result                                 Yes       Yes
sql_log_bin                                       Yes       Yes
sql_log_off                                       Yes       Yes
sql_log_update                                    Yes       Yes
sql_notes                                         Yes       Yes
sql_quote_show_create                             Yes       Yes
sql_safe_updates                                  Yes       Yes
sql_warnings                                      Yes       Yes
timestamp                                         Yes       Yes
unique_checks                                     Yes       Yes
warning_count                                     Yes       No

   *  `autocommit'

     The autocommit mode. If set to 1, all changes to a table take
     effect immediately. If set to 0, you must use *Note `COMMIT':
     commit. to accept a transaction or *Note `ROLLBACK': commit.  to
     cancel it. By default, client connections begin with `autocommit'
     set to 1. If you change `autocommit' mode from 0 to 1, MySQL
     performs an automatic *Note `COMMIT': commit. of any open
     transaction.  Another way to begin a transaction is to use a *Note
     `START TRANSACTION': commit. or *Note `BEGIN': commit.  statement.
     See *Note commit::.

   *  `backup_wait_timeout'

     The number of seconds DDL statements wait for a *Note `BACKUP
     DATABASE': backup-database. or *Note `RESTORE': restore. operation
     before aborting with an error. The default value is 50. A value of
     0 means `immediate timeout.' This variable was added in MySQL
     6.0.7.

   *  `big_tables'

     If set to 1, all temporary tables are stored on disk rather than
     in memory. This is a little slower, but the error `The table
     TBL_NAME is full' does not occur for *Note `SELECT': select.
     operations that require a large temporary table. The default value
     for a new connection is 0 (use in-memory temporary tables).
     Normally, you should never need to set this variable, because
     in-memory tables are automatically converted to disk-based tables
     as required.

     *Note*:

     This variable was formerly named `sql_big_tables'.

   *  `error_count'

     The number of errors that resulted from the last statement that
     generated messages. This variable is read only. See *Note
     show-errors::.

   *  `foreign_key_checks'

     If set to 1 (the default), foreign key constraints for `InnoDB'
     tables are checked. If set to 0, they are ignored. Disabling
     foreign key checking can be useful for reloading `InnoDB' tables
     in an order different from that required by their parent/child
     relationships. See *Note innodb-foreign-key-constraints::.

     Setting `foreign_key_checks' to 0 also affects data definition
     statements: *Note `DROP SCHEMA': drop-database. drops a schema
     even if it contains tables that have foreign keys that are
     referred to by tables outside the schema, and *Note `DROP TABLE':
     drop-table.  drops tables that have foreign keys that are referred
     to by other tables.

     *Note*:

     Setting `foreign_key_checks' to 1 does not trigger a scan of the
     existing table data.  Therefore, rows added to the table while
     `foreign_key_checks = 0' will not be verified for consistency.

   *  `identity'

     This variable is a synonym for the `last_insert_id' variable. It
     exists for compatibility with other database systems. You can read
     its value with `SELECT @@identity', and set it using `SET
     identity'.

   *  `insert_id'

     The value to be used by the following *Note `INSERT': insert. or
     *Note `ALTER TABLE': alter-table. statement when inserting an
     `AUTO_INCREMENT' value. This is mainly used with the binary log.

   *  `last_insert_id'

     The value to be returned from `LAST_INSERT_ID()'. This is stored
     in the binary log when you use `LAST_INSERT_ID()' in a statement
     that updates a table. Setting this variable does not update the
     value returned by the *Note `mysql_insert_id()': mysql-insert-id.
     C API function.

   *  `profiling'

     If set to 0 (the default), statement profiling is disabled. If set
     to 1, statement profiling is enabled and the *Note `SHOW
     PROFILES': show-profiles. and *Note `SHOW PROFILE': show-profile.
     statements provide access to profiling information. See *Note
     show-profiles::. This variable was added in MySQL 6.0.5.

   *  `profiling_history_size'

     The number of statements for which to maintain profiling
     information if `profiling' is enabled. The default value is 15.
     The maximum value is 100.  Setting the value to 0 effectively
     disables profiling. See *Note show-profiles::. This variable was
     added in MySQL 6.0.5.

   *  `rand_seed1'

     The `rand_seed1' and `rand_seed2' variables exist as session
     variables only, and can be set but not read. Beginning with MySQL
     6.0.5, the variables -- but not their values -- are shown in the
     output of *Note `SHOW VARIABLES': show-variables.

     The purpose of these variables is to support replication of the
     `RAND()' function. For statements that invoke `RAND()', the master
     passes two values to the slave, where they are used to seed the
     random number generator. The slave uses these values to set the
     session variables `rand_seed1' and `rand_seed2' so that `RAND()'
     on the slave generates the same value as on the master.

   *  `rand_seed2'

     See the description for `rand_seed1'.

   *  `sql_auto_is_null'

     If set to 1 (the default), you can find the last inserted row for
     a table that contains an `AUTO_INCREMENT' column by using the
     following construct:

          WHERE AUTO_INCREMENT_COLUMN IS NULL

     This behavior is used by some ODBC programs, such as Access.

   *  `sql_big_selects'

     If set to 0, MySQL aborts *Note `SELECT': select. statements that
     are likely to take a very long time to execute (that is,
     statements for which the optimizer estimates that the number of
     examined rows exceeds the value of `max_join_size'). This is
     useful when an inadvisable `WHERE' statement has been issued. The
     default value for a new connection is 1, which allows all *Note
     `SELECT': select.  statements.

     If you set the `max_join_size' system variable to a value other
     than `DEFAULT', `sql_big_selects' is set to 0.

   *  `sql_buffer_result'

     If set to 1, `sql_buffer_result' forces results from *Note
     `SELECT': select. statements to be put into temporary tables. This
     helps MySQL free the table locks early and can be beneficial in
     cases where it takes a long time to send results to the client.
     The default value is 0.

   *  `sql_log_bin'

     If set to 0, no logging is done to the binary log for the client.
     The client must have the `SUPER' privilege to set this option. The
     default value is 1.

   *  `sql_log_off'

     If set to 1, no logging is done to the general query log for this
     client. The client must have the `SUPER' privilege to set this
     option. The default value is 0.

   *  `sql_log_update'

     This variable is deprecated, and is mapped to `sql_log_bin'.

   *  `sql_notes'

     If set to 1 (the default), warnings of `Note' level are recorded.
     If set to 0, `Note' warnings are suppressed. *Note `mysqldump':
     mysqldump. includes output to set this variable to 0 so that
     reloading the dump file does not produce warnings for events that
     do not affect the integrity of the reload operation.

   *  `sql_quote_show_create'

     If set to 1 (the default), the server quotes identifiers for *Note
     `SHOW CREATE TABLE': show-create-table. and *Note `SHOW CREATE
     DATABASE': show-create-database.  statements. If set to 0, quoting
     is disabled. This option is enabled by default so that replication
     works for identifiers that require quoting. See *Note
     show-create-table::, and *Note show-create-database::.

   *  `sql_safe_updates'

     If set to 1, MySQL aborts *Note `UPDATE': update. or *Note
     `DELETE': delete. statements that do not use a key in the `WHERE'
     clause or a `LIMIT' clause. This makes it possible to catch *Note
     `UPDATE': update. or *Note `DELETE': delete. statements where keys
     are not used properly and that would probably change or delete a
     large number of rows. The default value is 0.

   *  `sql_warnings'

     This variable controls whether single-row *Note `INSERT': insert.
     statements produce an information string if warnings occur. The
     default is 0. Set the value to 1 to produce an information string.

   *  `timestamp = {TIMESTAMP_VALUE | DEFAULT}'

     Set the time for this client. This is used to get the original
     timestamp if you use the binary log to restore rows.
     TIMESTAMP_VALUE should be a Unix epoch timestamp, not a MySQL
     timestamp.

     `SET timestamp' affects the value returned by `NOW()' but not by
     `SYSDATE()'. This means that timestamp settings in the binary log
     have no effect on invocations of `SYSDATE()'. The server can be
     started with the `--sysdate-is-now' option to cause `SYSDATE()' to
     be an alias for `NOW()', in which case `SET timestamp' affects
     both functions.

   *  `unique_checks'

     If set to 1 (the default), uniqueness checks for secondary indexes
     in `InnoDB' tables are performed. If set to 0, storage engines are
     allowed to assume that duplicate keys are not present in input
     data. If you know for certain that your data does not contain
     uniqueness violations, you can set this to 0 to speed up large
     table imports to `InnoDB'.

     Note that setting this variable to 0 does not _require_ storage
     engines to ignore duplicate keys. An engine is still allowed to
     check for them and issue duplicate-key errors if it detects them.

   *  `warning_count'

     The number of errors, warnings, and notes that resulted from the
     last statement that generated messages. This variable is read
     only. See *Note show-warnings::.


File: manual.info,  Node: using-system-variables,  Next: server-status-variables,  Prev: server-session-variables,  Up: mysqld-server

5.1.5 Using System Variables
----------------------------

* Menu:

* structured-system-variables::  Structured System Variables
* dynamic-system-variables::     Dynamic System Variables

The MySQL server maintains many system variables that indicate how it
is configured. *Note server-system-variables::, describes the meaning
of these variables. Each system variable has a default value. System
variables can be set at server startup using options on the command
line or in an option file. Most of them can be changed dynamically
while the server is running by means of the *Note `SET': set-option.
statement, which enables you to modify operation of the server without
having to stop and restart it. You can refer to system variable values
in expressions.

The server maintains two kinds of system variables. Global variables
affect the overall operation of the server. Session variables affect
its operation for individual client connections.  A given system
variable can have both a global and a session value. Global and session
system variables are related as follows:

   * When the server starts, it initializes all global variables to
     their default values. These defaults can be changed by options
     specified on the command line or in an option file. (See *Note
     program-options::.)

   * The server also maintains a set of session variables for each
     client that connects. The client's session variables are
     initialized at connect time using the current values of the
     corresponding global variables. For example, the client's SQL mode
     is controlled by the session `sql_mode' value, which is
     initialized when the client connects to the value of the global
     `sql_mode' value.

System variable values can be set globally at server startup by using
options on the command line or in an option file. When you use a
startup option to set a variable that takes a numeric value, the value
can be given with a suffix of `K', `M', or `G' (either uppercase or
lowercase) to indicate a multiplier of 1024, 1024^2 or 1024^3; that is,
units of kilobytes, megabytes, or gigabytes, respectively. Thus, the
following command starts the server with a query cache size of 16
megabytes and a maximum packet size of one gigabyte:

     mysqld --query_cache_size=16M --max_allowed_packet=1G

Within an option file, those variables are set like this:

     [mysqld]
     query_cache_size=16M
     max_allowed_packet=1G

The lettercase of suffix letters does not matter; `16M' and `16m' are
equivalent, as are `1G' and `1g'.

If you want to restrict the maximum value to which a system variable
can be set at runtime with the *Note `SET': set-option.  statement, you
can specify this maximum by using an option of the form
`--maximum-VAR_NAME=VALUE' at server startup. For example, to prevent
the value of `query_cache_size' from being increased to more than 32MB
at runtime, use the option `--maximum-query_cache_size=32M'.

Many system variables are dynamic and can be changed while the server
runs by using the *Note `SET': set-option.  statement. For a list, see
*Note dynamic-system-variables::. To change a system variable with
*Note `SET': set-option, refer to it as VAR_NAME, optionally preceded
by a modifier:

   * To indicate explicitly that a variable is a global variable,
     precede its name by `GLOBAL' or `@@global.'. The `SUPER' privilege
     is required to set global variables.

   * To indicate explicitly that a variable is a session variable,
     precede its name by `SESSION', `@@session.', or `@@'.  Setting a
     session variable requires no special privilege, but a client can
     change only its own session variables, not those of any other
     client.

   * `LOCAL' and `@@local.' are synonyms for `SESSION' and `@@session.'.

   * If no modifier is present, *Note `SET': set-option.  changes the
     session variable.

A *Note `SET': set-option.  statement can contain multiple variable
assignments, separated by commas. If you set several system variables,
the most recent `GLOBAL' or `SESSION' modifier in the statement is used
for following variables that have no modifier specified.

Examples:

     SET sort_buffer_size=10000;
     SET @@local.sort_buffer_size=10000;
     SET GLOBAL sort_buffer_size=1000000, SESSION sort_buffer_size=1000000;
     SET @@sort_buffer_size=1000000;
     SET @@global.sort_buffer_size=1000000, @@local.sort_buffer_size=1000000;

The `@@VAR_NAME' syntax for system variables is supported for
compatibility with some other database systems.

If you change a session system variable, the value remains in effect
until your session ends or until you change the variable to a different
value. The change is not visible to other clients.

If you change a global system variable, the value is remembered and
used for new connections until the server restarts. (To make a global
system variable setting permanent, you should set it in an option
file.) The change is visible to any client that accesses that global
variable. However, the change affects the corresponding session
variable only for clients that connect after the change. The global
variable change does not affect the session variable for any client
that is currently connected (not even that of the client that issues the
*Note `SET GLOBAL': set-option.  statement).

To prevent incorrect usage, MySQL produces an error if you use *Note
`SET GLOBAL': set-option.  with a variable that can only be used with
*Note `SET SESSION': set-option.  or if you do not specify `GLOBAL' (or
`@@global.') when setting a global variable.

To set a `SESSION' variable to the `GLOBAL' value or a `GLOBAL' value
to the compiled-in MySQL default value, use the `DEFAULT' keyword. For
example, the following two statements are identical in setting the
session value of `max_join_size' to the global value:

     SET max_join_size=DEFAULT;
     SET @@session.max_join_size=@@global.max_join_size;

Not all system variables can be set to `DEFAULT'.  In such cases, use
of `DEFAULT' results in an error.

You can refer to the values of specific global or sesson system
variables in expressions by using one of the `@@'-modifiers. For
example, you can retrieve values in a *Note `SELECT': select. statement
like this:

     SELECT @@global.sql_mode, @@session.sql_mode, @@sql_mode;

When you refer to a system variable in an expression as `@@VAR_NAME'
(that is, when you do not specify `@@global.' or `@@session.'), MySQL
returns the session value if it exists and the global value otherwise.
(This differs from `SET @@VAR_NAME = VALUE', which always refers to the
session value.)

*Note*:

Some variables displayed by `SHOW VARIABLES' may not not be available
using `SELECT @@VAR_NAME' syntax; an `Unknown system variable' occurs.
As a workaround in such cases, you can use `SHOW VARIABLES LIKE
'VAR_NAME''.

Suffixes for specifying a value multiplier can be used when setting a
variable at server startup, but not to set the value with *Note `SET':
set-option. at runtime. On the other hand, with *Note `SET':
set-option. you can assign a variable's value using an expression,
which is not true when you set a variable at server startup. For
example, the first of the following lines is legal at server startup,
but the second is not:

     shell> mysql --max_allowed_packet=16M
     shell> mysql --max_allowed_packet=16*1024*1024

Conversely, the second of the following lines is legal at runtime, but
the first is not:

     mysql> SET GLOBAL max_allowed_packet=16M;
     mysql> SET GLOBAL max_allowed_packet=16*1024*1024;

*Note*:

Some system variables can be enabled with the *Note `SET': set-option.
statement by setting them to `ON' or `1', or disabled by setting them to
`OFF' or `0'. However, to set such a variable on the command line or in
an option file, you must set it to `1' or `0'; setting it to `ON' or
`OFF' will not work. For example, on the command line,
`--delay_key_write=1' works but `--delay_key_write=ON' does not.

To display system variable names and values, use the *Note `SHOW
VARIABLES': show-variables. statement:

     mysql> SHOW VARIABLES;
     +---------------------------------+-----------------------------------+
     | Variable_name                   | Value                             |
     +---------------------------------+-----------------------------------+
     | auto_increment_increment        | 1                                 |
     | auto_increment_offset           | 1                                 |
     | automatic_sp_privileges         | ON                                |
     | back_log                        | 50                                |
     | basedir                         | /home/mysql/                      |
     | binlog_cache_size               | 32768                             |
     | bulk_insert_buffer_size         | 8388608                           |
     | character_set_client            | latin1                            |
     | character_set_connection        | latin1                            |
     | character_set_database          | latin1                            |
     | character_set_results           | latin1                            |
     | character_set_server            | latin1                            |
     | character_set_system            | utf8                              |
     | character_sets_dir              | /home/mysql/share/mysql/charsets/ |
     | collation_connection            | latin1_swedish_ci                 |
     | collation_database              | latin1_swedish_ci                 |
     | collation_server                | latin1_swedish_ci                 |
     ...
     | innodb_additional_mem_pool_size | 1048576                           |
     | innodb_autoextend_increment     | 8                                 |
     | innodb_buffer_pool_size         | 8388608                           |
     | innodb_checksums                | ON                                |
     | innodb_commit_concurrency       | 0                                 |
     | innodb_concurrency_tickets      | 500                               |
     | innodb_data_file_path           | ibdata1:10M:autoextend            |
     | innodb_data_home_dir            |                                   |
     ...
     | version                         | 5.1.6-alpha-log                   |
     | version_comment                 | Source distribution               |
     | version_compile_machine         | i686                              |
     | version_compile_os              | suse-linux                        |
     | wait_timeout                    | 28800                             |
     +---------------------------------+-----------------------------------+

With a `LIKE' clause, the statement displays only those variables that
match the pattern. To obtain a specific variable name, use a `LIKE'
clause as shown:

     SHOW VARIABLES LIKE 'max_join_size';
     SHOW SESSION VARIABLES LIKE 'max_join_size';

To get a list of variables whose name match a pattern, use the ``%''
wildcard character in a `LIKE' clause:

     SHOW VARIABLES LIKE '%size%';
     SHOW GLOBAL VARIABLES LIKE '%size%';

Wildcard characters can be used in any position within the pattern to
be matched. Strictly speaking, because ``_'' is a wildcard that matches
any single character, you should escape it as ``\_'' to match it
literally. In practice, this is rarely necessary.

For *Note `SHOW VARIABLES': show-variables, if you specify neither
`GLOBAL' nor `SESSION', MySQL returns `SESSION' values.

The reason for requiring the `GLOBAL' keyword when setting
`GLOBAL'-only variables but not when retrieving them is to prevent
problems in the future. If we were to remove a `SESSION' variable that
has the same name as a `GLOBAL' variable, a client with the `SUPER'
privilege might accidentally change the `GLOBAL' variable rather than
just the `SESSION' variable for its own connection. If we add a
`SESSION' variable with the same name as a `GLOBAL' variable, a client
that intends to change the `GLOBAL' variable might find only its own
`SESSION' variable changed.


File: manual.info,  Node: structured-system-variables,  Next: dynamic-system-variables,  Prev: using-system-variables,  Up: using-system-variables

5.1.5.1 Structured System Variables
...................................

A structured variable differs from a regular system variable in two
respects:

   * Its value is a structure with components that specify server
     parameters considered to be closely related.

   * There might be several instances of a given type of structured
     variable. Each one has a different name and refers to a different
     resource maintained by the server.

MySQL 6.0 supports one structured variable type, which specifies
parameters governing the operation of key caches. A key cache
structured variable has these components:

   * `key_buffer_size'

   * `key_cache_block_size'

   * `key_cache_division_limit'

   * `key_cache_age_threshold'

This section describes the syntax for referring to structured
variables. Key cache variables are used for syntax examples, but
specific details about how key caches operate are found elsewhere, in
*Note myisam-key-cache::.

To refer to a component of a structured variable instance, you can use
a compound name in INSTANCE_NAME.COMPONENT_NAME format.  Examples:

     hot_cache.key_buffer_size
     hot_cache.key_cache_block_size
     cold_cache.key_cache_block_size

For each structured system variable, an instance with the name of
`default' is always predefined. If you refer to a component of a
structured variable without any instance name, the `default' instance
is used. Thus, `default.key_buffer_size' and `key_buffer_size' both
refer to the same system variable.

Structured variable instances and components follow these naming rules:

   * For a given type of structured variable, each instance must have a
     name that is unique _within_ variables of that type. However,
     instance names need not be unique _across_ structured variable
     types. For example, each structured variable has an instance named
     `default', so `default' is not unique across variable types.

   * The names of the components of each structured variable type must
     be unique across all system variable names. If this were not true
     (that is, if two different types of structured variables could
     share component member names), it would not be clear which default
     structured variable to use for references to member names that are
     not qualified by an instance name.

   * If a structured variable instance name is not legal as an unquoted
     identifier, refer to it as a quoted identifier using backticks.
     For example, `hot-cache' is not legal, but ``hot-cache`' is.

   * `global', `session', and `local' are not legal instance names. This
     avoids a conflict with notation such as `@@global.VAR_NAME' for
     referring to non-structured system variables.

Currently, the first two rules have no possibility of being violated
because the only structured variable type is the one for key caches.
These rules will assume greater significance if some other type of
structured variable is created in the future.

With one exception, you can refer to structured variable components
using compound names in any context where simple variable names can
occur. For example, you can assign a value to a structured variable
using a command-line option:

     shell> mysqld --hot_cache.key_buffer_size=64K

In an option file, use this syntax:

     [mysqld]
     hot_cache.key_buffer_size=64K

If you start the server with this option, it creates a key cache named
`hot_cache' with a size of 64KB in addition to the default key cache
that has a default size of 8MB.

Suppose that you start the server as follows:

     shell> mysqld --key_buffer_size=256K \
              --extra_cache.key_buffer_size=128K \
              --extra_cache.key_cache_block_size=2048

In this case, the server sets the size of the default key cache to
256KB. (You could also have written `--default.key_buffer_size=256K'.)
In addition, the server creates a second key cache named `extra_cache'
that has a size of 128KB, with the size of block buffers for caching
table index blocks set to 2048 bytes.

The following example starts the server with three different key caches
having sizes in a 3:1:1 ratio:

     shell> mysqld --key_buffer_size=6M \
              --hot_cache.key_buffer_size=2M \
              --cold_cache.key_buffer_size=2M

Structured variable values may be set and retrieved at runtime as well.
For example, to set a key cache named `hot_cache' to a size of 10MB,
use either of these statements:

     mysql> SET GLOBAL hot_cache.key_buffer_size = 10*1024*1024;
     mysql> SET @@global.hot_cache.key_buffer_size = 10*1024*1024;

To retrieve the cache size, do this:

     mysql> SELECT @@global.hot_cache.key_buffer_size;

However, the following statement does not work. The variable is not
interpreted as a compound name, but as a simple string for a `LIKE'
pattern-matching operation:

     mysql> SHOW GLOBAL VARIABLES LIKE 'hot_cache.key_buffer_size';

This is the exception to being able to use structured variable names
anywhere a simple variable name may occur.


File: manual.info,  Node: dynamic-system-variables,  Prev: structured-system-variables,  Up: using-system-variables

5.1.5.2 Dynamic System Variables
................................

Many server system variables are dynamic and can be set at runtime
using *Note `SET GLOBAL': set-option. or *Note `SET SESSION':
set-option. You can also obtain their values using *Note `SELECT':
select. See *Note using-system-variables::.

The following table shows the full list of all dynamic system
variables. The last column indicates for each variable whether `GLOBAL'
or `SESSION' (or both) apply. The table also lists session options that
can be set with the *Note `SET': set-option.  statement. *Note
server-session-variables::, discusses these options.

Variables that have a type of `string' take a string value. Variables
that have a type of `numeric' take a numeric value. Variables that have
a type of `boolean' can be set to 0, 1, `ON' or `OFF'. (If you set them
on the command line or in an option file, use the numeric values.)
Variables that are marked as `enumeration' normally should be set to
one of the available values for the variable, but can also be set to
the number that corresponds to the desired enumeration value. For
enumerated system variables, the first enumeration value corresponds to
0. This differs from *Note `ENUM': enum. columns, for which the first
enumeration value corresponds to 1.

*Variable Name*                             *Variable      *Variable
                                            Type*          Scope*
`auto_increment_increment'                  numeric        `GLOBAL' |
                                                           `SESSION'
`auto_increment_offset'                     numeric        `GLOBAL' |
                                                           `SESSION'
`autocommit'                                boolean        `SESSION'
`automatic_sp_privileges'                   boolean        `GLOBAL'
`backup_history_log'                        boolean        `GLOBAL'
`backup_history_log_file'                   filename       `GLOBAL'
`backup_progress_log'                       boolean        `GLOBAL'
`backup_progress_log_file'                  filename       `GLOBAL'
`backup_wait_timeout'                       numeric        `SESSION'
`backupdir'                                 filename       `GLOBAL'
`big_tables'                                boolean        `SESSION'
`binlog_cache_size'                         numeric        `GLOBAL'
`binlog_format'                             enumeration    `GLOBAL' |
                                                           `SESSION'
`bulk_insert_buffer_size'                   numeric        `GLOBAL' |
                                                           `SESSION'
`character_set_client'                      string         `GLOBAL' |
                                                           `SESSION'
`character_set_connection'                  string         `GLOBAL' |
                                                           `SESSION'
`character_set_database'                    string         `GLOBAL' |
                                                           `SESSION'
`character_set_filesystem'                  string         `GLOBAL' |
                                                           `SESSION'
`character_set_results'                     string         `GLOBAL' |
                                                           `SESSION'
`character_set_server'                      string         `GLOBAL' |
                                                           `SESSION'
`collation_connection'                      string         `GLOBAL' |
                                                           `SESSION'
`collation_database'                        string         `GLOBAL' |
                                                           `SESSION'
`collation_server'                          string         `GLOBAL' |
                                                           `SESSION'
`completion_type'                           numeric        `GLOBAL' |
                                                           `SESSION'
`concurrent_insert'                         boolean        `GLOBAL'
`connect_timeout'                           numeric        `GLOBAL'
`date_format'                               string         `GLOBAL' |
                                                           `SESSION'
`datetime_format'                           string         `GLOBAL' |
                                                           `SESSION'
`debug'                                     string         `GLOBAL' |
                                                           `SESSION'
`debug_sync'                                string         `GLOBAL' |
                                                           `SESSION'
`default_week_format'                       numeric        `GLOBAL' |
                                                           `SESSION'
`delay_key_write'                           enumeration    `GLOBAL'
`delayed_insert_limit'                      numeric        `GLOBAL'
`delayed_insert_timeout'                    numeric        `GLOBAL'
`delayed_queue_size'                        numeric        `GLOBAL'
`div_precision_increment'                   numeric        `GLOBAL' |
                                                           `SESSION'
`engine_condition_pushdown'                 boolean        `GLOBAL' |
                                                           `SESSION'
`event_scheduler'                           enumeration    `GLOBAL'
`expire_logs_days'                          numeric        `GLOBAL'
`falcon_checkpoint_schedule'                string         `GLOBAL'
`falcon_checksums'                          boolean        `GLOBAL'
`falcon_consistent_read'                    boolean        `GLOBAL' |
                                                           `SESSION'
`falcon_debug_mask'                         bitmap         `GLOBAL'
`falcon_disable_fsync'                      boolean        `GLOBAL'
`falcon_index_chill_threshold'              numeric        `GLOBAL'
`falcon_initial_allocation'                 numeric        `GLOBAL'
`falcon_io_threads'                         numeric        `GLOBAL'
`falcon_lock_wait_timeout'                  numeric        `GLOBAL'
`falcon_max_transaction_backlog'            numeric        `GLOBAL'
`falcon_record_chill_threshold'             numeric        `GLOBAL'
`falcon_record_memory_max'                  numeric        `GLOBAL'
`falcon_record_scavenge_floor'              numeric        `GLOBAL'
`falcon_record_scavenge_threshold'          numeric        `GLOBAL'
`falcon_serial_log_priority'                boolean        `GLOBAL'
`flush'                                     boolean        `GLOBAL'
`flush_time'                                numeric        `GLOBAL'
`foreign_key_checks'                        boolean        `SESSION'
`ft_boolean_syntax'                         string         `GLOBAL'
`general_log'                               boolean        `GLOBAL'
`general_log_file'                          filename       `GLOBAL'
`group_concat_max_len'                      numeric        `GLOBAL' |
                                                           `SESSION'
`identity'                                  numeric        `SESSION'
`init_connect'                              string         `GLOBAL'
`init_slave'                                string         `GLOBAL'
`innodb_autoextend_increment'               numeric        `GLOBAL'
`innodb_commit_concurrency'                 numeric        `GLOBAL'
`innodb_concurrency_tickets'                numeric        `GLOBAL'
`innodb_fast_shutdown'                      boolean        `GLOBAL'
`innodb_flush_log_at_trx_commit'            numeric        `GLOBAL'
`innodb_max_dirty_pages_pct'                numeric        `GLOBAL'
`innodb_max_purge_lag'                      numeric        `GLOBAL'
`innodb_stats_on_metadata'                  boolean        `GLOBAL'
`innodb_support_xa'                         boolean        `GLOBAL' |
                                                           `SESSION'
`innodb_sync_spin_loops'                    numeric        `GLOBAL'
`innodb_table_locks'                        boolean        `GLOBAL' |
                                                           `SESSION'
`innodb_thread_concurrency'                 numeric        `GLOBAL'
`innodb_thread_sleep_delay'                 numeric        `GLOBAL'
`insert_id'                                 numeric        `SESSION'
`interactive_timeout'                       numeric        `GLOBAL' |
                                                           `SESSION'
`join_buffer_size'                          numeric        `GLOBAL' |
                                                           `SESSION'
`join_cache_level'                          numeric        `GLOBAL' |
                                                           `SESSION'
`keep_files_on_create'                      boolean        `GLOBAL' |
                                                           `SESSION'
`key_buffer_size'                           numeric        `GLOBAL'
`key_cache_age_threshold'                   numeric        `GLOBAL'
`key_cache_block_size'                      numeric        `GLOBAL'
`key_cache_division_limit'                  numeric        `GLOBAL'
`last_insert_id'                            numeric        `SESSION'
`lc_time_names'                             string         `GLOBAL' |
                                                           `SESSION'
`local_infile'                                             `GLOBAL'
`log'                                       string         `GLOBAL'
`log_backup_output'                         enumeration    `GLOBAL'
`log_bin_trust_function_creators'           boolean        `GLOBAL'
`log_output'                                enumeration    `GLOBAL'
`log_queries_not_using_indexes'             boolean        `GLOBAL'
`log_slow_queries'                          boolean        `GLOBAL'
`log_warnings'                              numeric        `GLOBAL' |
                                                           `SESSION'
`long_query_time'                           numeric        `GLOBAL' |
                                                           `SESSION'
`low_priority_updates'                      boolean        `GLOBAL' |
                                                           `SESSION'
`maria-checkpoint-interval'                                `GLOBAL'
`maria_log_file_size'                       numeric        `GLOBAL'
`maria_log_purge_type'                      enumeration    `GLOBAL'
`maria_max_sort_file_size'                                 `GLOBAL'
`maria_page_checksum'                       enumeration    `GLOBAL'
`maria_pagecache_age_threshold'             numeric        `GLOBAL'
`maria_pagecache_division_limit'            numeric        `GLOBAL'
`maria_recover'                             boolean        `GLOBAL'
`maria_repair_threads'                      numeric        `GLOBAL' |
                                                           `SESSION'
`maria_sort_buffer_size'                    numeric        `GLOBAL' |
                                                           `SESSION'
`maria_stats_method'                        enumeration    `GLOBAL' |
                                                           `SESSION'
`maria_sync_log_dir'                        enumeration    `GLOBAL'
`max_allowed_packet'                        numeric        `GLOBAL' |
                                                           `SESSION'
`max_binlog_cache_size'                     numeric        `GLOBAL'
`max_binlog_size'                           numeric        `GLOBAL'
`max_connect_errors'                        numeric        `GLOBAL'
`max_connections'                           numeric        `GLOBAL'
`max_delayed_threads'                       numeric        `GLOBAL' |
                                                           `SESSION'
`max_error_count'                           numeric        `GLOBAL' |
                                                           `SESSION'
`max_heap_table_size'                       numeric        `GLOBAL' |
                                                           `SESSION'
`max_insert_delayed_threads'                numeric        `GLOBAL' |
                                                           `SESSION'
`max_join_size'                             numeric        `GLOBAL' |
                                                           `SESSION'
`max_length_for_sort_data'                  numeric        `GLOBAL' |
                                                           `SESSION'
`max_prepared_stmt_count'                   numeric        `GLOBAL'
`max_relay_log_size'                        numeric        `GLOBAL'
`max_seeks_for_key'                         numeric        `GLOBAL' |
                                                           `SESSION'
`max_sort_length'                           numeric        `GLOBAL' |
                                                           `SESSION'
`max_sp_recursion_depth'                    numeric        `GLOBAL' |
                                                           `SESSION'
`max_tmp_tables'                            numeric        `GLOBAL' |
                                                           `SESSION'
`max_user_connections'                      numeric        `GLOBAL' |
                                                           `SESSION'
`max_write_lock_count'                      numeric        `GLOBAL'
`min_examined_row_limit'                    numeric        `GLOBAL' |
                                                           `SESSION'
`myisam_data_pointer_size'                  numeric        `GLOBAL'
`myisam_max_sort_file_size'                 numeric        `GLOBAL'
`myisam_repair_threads'                     numeric        `GLOBAL' |
                                                           `SESSION'
`myisam_sort_buffer_size'                   numeric        `GLOBAL' |
                                                           `SESSION'
`myisam_stats_method'                       enumeration    `GLOBAL' |
                                                           `SESSION'
`myisam_use_mmap'                           boolean        `GLOBAL'
`ndb_autoincrement_prefetch_sz'             numeric        `GLOBAL' |
                                                           `SESSION'
`net_buffer_length'                         numeric        `GLOBAL' |
                                                           `SESSION'
`net_read_timeout'                          numeric        `GLOBAL' |
                                                           `SESSION'
`net_retry_count'                           numeric        `GLOBAL' |
                                                           `SESSION'
`net_write_timeout'                         numeric        `GLOBAL' |
                                                           `SESSION'
`new'                                       boolean        `GLOBAL' |
                                                           `SESSION'
`old_passwords'                             boolean        `GLOBAL' |
                                                           `SESSION'
`optimizer_prune_level'                     boolean        `GLOBAL' |
                                                           `SESSION'
`optimizer_search_depth'                    numeric        `GLOBAL' |
                                                           `SESSION'
`optimizer_switch'                          enumeration    `GLOBAL' |
                                                           `SESSION'
`optimizer_use_mrr'                         enumeration    `GLOBAL' |
                                                           `SESSION'
`preload_buffer_size'                       numeric        `GLOBAL' |
                                                           `SESSION'
`profiling'                                 boolean        `SESSION'
`profiling_history_size'                    numeric        `GLOBAL' |
                                                           `SESSION'
`query_alloc_block_size'                    numeric        `GLOBAL' |
                                                           `SESSION'
`query_cache_limit'                         numeric        `GLOBAL'
`query_cache_min_res_unit'                  numeric        `GLOBAL'
`query_cache_size'                          numeric        `GLOBAL'
`query_cache_type'                          enumeration    `GLOBAL' |
                                                           `SESSION'
`query_cache_wlock_invalidate'              boolean        `GLOBAL' |
                                                           `SESSION'
`query_prealloc_size'                       numeric        `GLOBAL' |
                                                           `SESSION'
`rand_seed1'                                numeric        `SESSION'
`rand_seed2'                                numeric        `SESSION'
`range_alloc_block_size'                    numeric        `GLOBAL' |
                                                           `SESSION'
`read_buffer_size'                          numeric        `GLOBAL' |
                                                           `SESSION'
`read_only'                                 numeric        `GLOBAL'
`read_rnd_buffer_size'                      numeric        `GLOBAL' |
                                                           `SESSION'
`relay_log_purge'                           boolean        `GLOBAL'
`relay_log_recovery'                        boolean        `GLOBAL'
`rpl_recovery_rank'                         numeric        `GLOBAL'
`rpl_semi_sync_master_enabled'              numeric        `GLOBAL'
`rpl_semi_sync_master_reply_log_file_pos'   string         `GLOBAL'
`rpl_semi_sync_master_timeout'              numeric        `GLOBAL'
`rpl_semi_sync_master_trace_level'          numeric        `GLOBAL'
`rpl_semi_sync_slave_enabled'               numeric        `GLOBAL'
`rpl_semi_sync_slave_trace_level'           numeric        `GLOBAL'
`secure_auth'                               boolean        `GLOBAL'
`server_id'                                 numeric        `GLOBAL'
`slave_compressed_protocol'                 boolean        `GLOBAL'
`slave_exec_mode'                           enumeration    `GLOBAL'
`slave_net_timeout'                         numeric        `GLOBAL'
`slave_transaction_retries'                 numeric        `GLOBAL'
`slow_launch_time'                          numeric        `GLOBAL'
`slow_query_log'                            boolean        `GLOBAL'
`slow_query_log_file'                       filename       `GLOBAL'
`sort_buffer_size'                          numeric        `GLOBAL' |
                                                           `SESSION'
`sql_auto_is_null'                          boolean        `SESSION'
`sql_big_selects'                           boolean        `SESSION'
`sql_big_tables'                            boolean        `SESSION'
`sql_buffer_result'                         boolean        `SESSION'
`sql_log_bin'                               boolean        `SESSION'
`sql_log_off'                               boolean        `SESSION'
`sql_log_update'                            boolean        `SESSION'
`sql_low_priority_updates'                  boolean        `GLOBAL' |
                                                           `SESSION'
`sql_max_join_size'                         numeric        `GLOBAL' |
                                                           `SESSION'
`sql_mode'                                  set            `GLOBAL' |
                                                           `SESSION'
`sql_notes'                                 boolean        `SESSION'
`sql_quote_show_create'                     boolean        `SESSION'
`sql_safe_updates'                          boolean        `SESSION'
`sql_select_limit'                          numeric        `GLOBAL' |
                                                           `SESSION'
`sql_slave_skip_counter'                    numeric        `GLOBAL'
`sql_warnings'                              boolean        `SESSION'
`storage_engine'                            enumeration    `GLOBAL' |
                                                           `SESSION'
`sync_binlog'                               numeric        `GLOBAL'
`sync_frm'                                  boolean        `GLOBAL'
`sync_master_info'                          numeric        `GLOBAL'
`sync_relay_log'                            numeric        `GLOBAL'
`sync_relay_log_info'                       numeric        `GLOBAL'
`table_cache'                               numeric        `GLOBAL'
`table_definition_cache'                    numeric        `GLOBAL'
`table_lock_wait_timeout'                   numeric        `GLOBAL'
`table_open_cache'                          numeric        `GLOBAL'
`thread_cache_size'                         numeric        `GLOBAL'
`time_format'                               string         `GLOBAL' |
                                                           `SESSION'
`time_zone'                                 string         `GLOBAL' |
                                                           `SESSION'
`timed_mutexes'                             boolean        `GLOBAL'
`timestamp'                                 string         `SESSION'
`tmp_table_size'                            numeric        `GLOBAL' |
                                                           `SESSION'
`transaction_alloc_block_size'              numeric        `GLOBAL' |
                                                           `SESSION'
`transaction_prealloc_size'                 numeric        `GLOBAL' |
                                                           `SESSION'
`tx_isolation'                              enumeration    `GLOBAL' |
                                                           `SESSION'
`unique_checks'                             boolean        `SESSION'
`updatable_views_with_limit'                boolean        `GLOBAL' |
                                                           `SESSION'
`wait_timeout'                              numeric        `GLOBAL' |
                                                           `SESSION'

MySQL Enterprise

Improper configuration of system variables can adversely affect
performance and security. The MySQL Enterprise Monitor continually
monitors system variables and provides expert advice about appropriate
settings. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: server-status-variables,  Next: server-sql-mode,  Prev: using-system-variables,  Up: mysqld-server

5.1.6 Server Status Variables
-----------------------------

The server maintains many status variables that provide information
about its operation. You can view these variables and their values by
using the `SHOW [GLOBAL | SESSION] STATUS' statement (see *Note
show-status::).  The optional `GLOBAL' keyword aggregates the values
over all connections, and `SESSION' shows the values for the current
connection.

     mysql> SHOW GLOBAL STATUS;
     +-----------------------------------+------------+
     | Variable_name                     | Value      |
     +-----------------------------------+------------+
     | Aborted_clients                   | 0          |
     | Aborted_connects                  | 0          |
     | Bytes_received                    | 155372598  |
     | Bytes_sent                        | 1176560426 |
     ...
     | Connections                       | 30023      |
     | Created_tmp_disk_tables           | 0          |
     | Created_tmp_files                 | 3          |
     | Created_tmp_tables                | 2          |
     ...
     | Threads_created                   | 217        |
     | Threads_running                   | 88         |
     | Uptime                            | 1389872    |
     +-----------------------------------+------------+

The following table lists all available server status variables:

*Variable Name*                             *Variable      *Variable
                                            Type*          Scope*
`Aborted_clients'                           numeric        `GLOBAL'
`Aborted_connects'                          numeric        `GLOBAL'
`Binlog_cache_disk_use'                     numeric        `GLOBAL'
`Binlog_cache_use'                          numeric        `GLOBAL'
`Bytes_received'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Bytes_sent'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_admin_commands'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_alter_db'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_alter_event'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_alter_table'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_analyze'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_backup'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_backup_table'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_begin'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_call_procedure'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_change_db'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_change_master'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_check'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_checksum'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_commit'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_db'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_event'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_function'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_index'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_table'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_user'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_dealloc_sql'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_delete'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_delete_multi'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_do'                                    numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_db'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_event'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_function'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_index'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_table'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_user'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_execute_sql'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_flush'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_grant'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_ha_close'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_ha_open'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_ha_read'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_help'                                  numeric        `GLOBAL' |
                                                           `SESSION'
`Com_insert'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_insert_select'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_kill'                                  numeric        `GLOBAL' |
                                                           `SESSION'
`Com_load'                                  numeric        `GLOBAL' |
                                                           `SESSION'
`Com_lock_tables'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_optimize'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_preload_keys'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_prepare_sql'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_purge'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_purge_before_date'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_rename_table'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_repair'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_replace'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_replace_select'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_reset'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_restore'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_restore_table'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_revoke'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_revoke_all'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_rollback'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_savepoint'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_select'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_set_option'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_binlog_events'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_binlogs'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_charsets'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_collations'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_column_types'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_create_db'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_create_event'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_create_table'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_databases'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_engine_logs'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_engine_mutex'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_engine_status'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_errors'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_events'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_fields'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_grants'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_innodb_status'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_keys'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_logs'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_master_status'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_ndb_status'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_new_master'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_open_tables'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_plugins'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_privileges'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_processlist'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_profile'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_profiles'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_slave_hosts'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_slave_status'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_status'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_storage_engines'                  numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_tables'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_triggers'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_variables'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_warnings'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_slave_start'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_slave_stop'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_close'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_execute'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_fetch'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_prepare'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_reprepare'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_reset'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_send_long_data'                   numeric        `GLOBAL' |
                                                           `SESSION'
`Com_truncate'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_unlock_tables'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_update'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_update_multi'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_commit'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_end'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_prepare'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_recover'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_rollback'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_start'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Compression'                               numeric        `SESSION'
`Connections'                               numeric        `GLOBAL'
`Created_tmp_disk_tables'                   numeric        `GLOBAL' |
                                                           `SESSION'
`Created_tmp_files'                         numeric        `GLOBAL'
`Created_tmp_tables'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Delayed_errors'                            numeric        `GLOBAL'
`Delayed_insert_threads'                    numeric        `GLOBAL'
`Delayed_writes'                            numeric        `GLOBAL'
`Flush_commands'                            numeric        `GLOBAL'
`Handler_commit'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_delete'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_discover'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_prepare'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_first'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_key'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_next'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_prev'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_rnd'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_rnd_next'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_rollback'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_savepoint'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_savepoint_rollback'                numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_update'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_write'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Innodb_buffer_pool_pages_data'             numeric        `GLOBAL'
`Innodb_buffer_pool_pages_dirty'            numeric        `GLOBAL'
`Innodb_buffer_pool_pages_flushed'          numeric        `GLOBAL'
`Innodb_buffer_pool_pages_free'             numeric        `GLOBAL'
`Innodb_buffer_pool_pages_latched'          numeric        `GLOBAL'
`Innodb_buffer_pool_pages_misc'             numeric        `GLOBAL'
`Innodb_buffer_pool_pages_total'            numeric        `GLOBAL'
`Innodb_buffer_pool_read_ahead_rnd'         numeric        `GLOBAL'
`Innodb_buffer_pool_read_ahead_seq'         numeric        `GLOBAL'
`Innodb_buffer_pool_read_requests'          numeric        `GLOBAL'
`Innodb_buffer_pool_reads'                  numeric        `GLOBAL'
`Innodb_buffer_pool_wait_free'              numeric        `GLOBAL'
`Innodb_buffer_pool_write_requests'         numeric        `GLOBAL'
`Innodb_data_fsyncs'                        numeric        `GLOBAL'
`Innodb_data_pending_fsyncs'                numeric        `GLOBAL'
`Innodb_data_pending_reads'                 numeric        `GLOBAL'
`Innodb_data_pending_writes'                numeric        `GLOBAL'
`Innodb_data_read'                          numeric        `GLOBAL'
`Innodb_data_reads'                         numeric        `GLOBAL'
`Innodb_data_writes'                        numeric        `GLOBAL'
`Innodb_data_written'                       numeric        `GLOBAL'
`Innodb_dblwr_pages_written'                numeric        `GLOBAL'
`Innodb_dblwr_writes'                       numeric        `GLOBAL'
`Innodb_log_waits'                          numeric        `GLOBAL'
`Innodb_log_write_requests'                 numeric        `GLOBAL'
`Innodb_log_writes'                         numeric        `GLOBAL'
`Innodb_os_log_fsyncs'                      numeric        `GLOBAL'
`Innodb_os_log_pending_fsyncs'              numeric        `GLOBAL'
`Innodb_os_log_pending_writes'              numeric        `GLOBAL'
`Innodb_os_log_written'                     numeric        `GLOBAL'
`Innodb_page_size'                          numeric        `GLOBAL'
`Innodb_pages_created'                      numeric        `GLOBAL'
`Innodb_pages_read'                         numeric        `GLOBAL'
`Innodb_pages_written'                      numeric        `GLOBAL'
`Innodb_row_lock_current_waits'             numeric        `GLOBAL'
`Innodb_row_lock_time'                      numeric        `GLOBAL'
`Innodb_row_lock_time_avg'                  numeric        `GLOBAL'
`Innodb_row_lock_time_max'                  numeric        `GLOBAL'
`Innodb_row_lock_waits'                     numeric        `GLOBAL'
`Innodb_rows_deleted'                       numeric        `GLOBAL'
`Innodb_rows_inserted'                      numeric        `GLOBAL'
`Innodb_rows_read'                          numeric        `GLOBAL'
`Innodb_rows_updated'                       numeric        `GLOBAL'
`Key_blocks_not_flushed'                    numeric        `GLOBAL'
`Key_blocks_unused'                         numeric        `GLOBAL'
`Key_blocks_used'                           numeric        `GLOBAL'
`Key_read_requests'                         numeric        `GLOBAL'
`Key_reads'                                 numeric        `GLOBAL'
`Key_write_requests'                        numeric        `GLOBAL'
`Key_writes'                                numeric        `GLOBAL'
`Last_query_cost'                           numeric        `SESSION'
`Max_used_connections'                      numeric        `GLOBAL'
`Ndb_cluster_node_id'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Ndb_config_from_host'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Ndb_config_from_port'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Ndb_conflict_fn_max'                       numeric        `GLOBAL'
`Ndb_conflict_fn_old'                       numeric        `GLOBAL'
`Ndb_number_of_data_nodes'                  numeric        `GLOBAL'
`Not_flushed_delayed_rows'                  numeric        `GLOBAL'
`Open_files'                                numeric        `GLOBAL'
`Open_streams'                              numeric        `GLOBAL'
`Open_table_definitions'                    numeric        `GLOBAL'
`Open_tables'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Opened_files'                              numeric        `GLOBAL'
`Opened_table_definitions'                  numeric        `GLOBAL' |
                                                           `SESSION'
`Opened_tables'                             numeric        `GLOBAL' |
                                                           `SESSION'
`prepared_stmt_count'                       numeric        `GLOBAL'
`Qcache_free_blocks'                        numeric        `GLOBAL'
`Qcache_free_memory'                        numeric        `GLOBAL'
`Qcache_hits'                               numeric        `GLOBAL'
`Qcache_inserts'                            numeric        `GLOBAL'
`Qcache_lowmem_prunes'                      numeric        `GLOBAL'
`Qcache_not_cached'                         numeric        `GLOBAL'
`Qcache_queries_in_cache'                   numeric        `GLOBAL'
`Qcache_total_blocks'                       numeric        `GLOBAL'
`Queries'                                   numeric        `GLOBAL' |
                                                           `SESSION'
`Questions'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Rpl_semi_sync_master_clients'              numeric        `GLOBAL'
`Rpl_semi_sync_master_net_avg_wait_time'    numeric        `GLOBAL'
`Rpl_semi_sync_master_net_wait_time'        numeric        `GLOBAL'
`Rpl_semi_sync_master_net_waits'            numeric        `GLOBAL'
`Rpl_semi_sync_master_no_times'             numeric        `GLOBAL'
`Rpl_semi_sync_master_no_tx'                numeric        `GLOBAL'
`Rpl_semi_sync_master_status'               numeric        `GLOBAL'
`Rpl_semi_sync_master_timefunc_failures'    numeric        `GLOBAL'
`Rpl_semi_sync_master_tx_avg_wait_time'     numeric        `GLOBAL'
`Rpl_semi_sync_master_tx_wait_time'         numeric        `GLOBAL'
`Rpl_semi_sync_master_tx_waits'             numeric        `GLOBAL'
`Rpl_semi_sync_master_wait_pos_backtraverse'numeric        `GLOBAL'
`Rpl_semi_sync_master_wait_sessions'        numeric        `GLOBAL'
`Rpl_semi_sync_master_yes_tx'               numeric        `GLOBAL'
`Rpl_semi_sync_slave_status'                numeric        `GLOBAL'
`Rpl_status'                                string         `GLOBAL'
`Select_full_join'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Select_full_range_join'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Select_range'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Select_range_check'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Select_scan'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Slave_heartbeat_period'                                   `GLOBAL'
`Slave_open_temp_tables'                    numeric        `GLOBAL'
`Slave_received_heartbeats'                                `GLOBAL'
`Slave_retried_transactions'                numeric        `GLOBAL'
`Slave_running'                             boolean        `GLOBAL'
`Slow_launch_threads'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Slow_queries'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Sort_merge_passes'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Sort_range'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Sort_rows'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Sort_scan'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Ssl_accept_renegotiates'                   numeric        `GLOBAL'
`Ssl_accepts'                               numeric        `GLOBAL'
`Ssl_callback_cache_hits'                   numeric        `GLOBAL'
`Ssl_cipher'                                string         `GLOBAL' |
                                                           `SESSION'
`Ssl_cipher_list'                           string         `GLOBAL' |
                                                           `SESSION'
`Ssl_client_connects'                       numeric        `GLOBAL'
`Ssl_connect_renegotiates'                  numeric        `GLOBAL'
`Ssl_ctx_verify_depth'                      numeric        `GLOBAL'
`Ssl_ctx_verify_mode'                       numeric        `GLOBAL'
`Ssl_default_timeout'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Ssl_finished_accepts'                      numeric        `GLOBAL'
`Ssl_finished_connects'                     numeric        `GLOBAL'
`Ssl_session_cache_hits'                    numeric        `GLOBAL'
`Ssl_session_cache_misses'                  numeric        `GLOBAL'
`Ssl_session_cache_mode'                    string         `GLOBAL'
`Ssl_session_cache_overflows'               numeric        `GLOBAL'
`Ssl_session_cache_size'                    numeric        `GLOBAL'
`Ssl_session_cache_timeouts'                numeric        `GLOBAL'
`Ssl_sessions_reused'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Ssl_used_session_cache_entries'            numeric        `GLOBAL'
`Ssl_verify_depth'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Ssl_verify_mode'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Ssl_version'                               string         `GLOBAL' |
                                                           `SESSION'
`Table_locks_immediate'                     numeric        `GLOBAL'
`Table_locks_waited'                        numeric        `GLOBAL'
`Tc_log_max_pages_used'                     numeric        `GLOBAL'
`Tc_log_page_size'                          numeric        `GLOBAL'
`Tc_log_page_waits'                         numeric        `GLOBAL'
`Threads_cached'                            numeric        `GLOBAL'
`Threads_connected'                         numeric        `GLOBAL'
`Threads_created'                           numeric        `GLOBAL'
`Threads_running'                           numeric        `GLOBAL'
`Uptime'                                    numeric        `GLOBAL'
`Uptime_since_flush_status'                 numeric        `GLOBAL'

Many status variables are reset to 0 by the `FLUSH STATUS' statement.

MySQL Enterprise

For expert advice on using status variables, subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The status variables have the following meanings. Variables with no
version indicated were already present prior to MySQL 6.0. For
information regarding their implementation history, see `MySQL 5.1
Reference Manual'.

   *  `Aborted_clients'

     The number of connections that were aborted because the client
     died without closing the connection properly. See *Note
     communication-errors::.

   *  `Aborted_connects'

     The number of failed attempts to connect to the MySQL server.  See
     *Note communication-errors::.

   *  `Binlog_cache_disk_use'

     The number of transactions that used the temporary binary log
     cache but that exceeded the value of `binlog_cache_size' and used a
     temporary file to store statements from the transaction.

   *  `Binlog_cache_use'

     The number of transactions that used the temporary binary log
     cache.

   *  `Bytes_received'

     The number of bytes received from all clients.

   *  `Bytes_sent'

     The number of bytes sent to all clients.

   *  `Com_XXX'

     The `Com_XXX' statement counter variables indicate the number of
     times each XXX statement has been executed.  There is one status
     variable for each type of statement. For example, `Com_delete' and
     `Com_insert' count *Note `DELETE': delete. and *Note `INSERT':
     insert. statements, respectively. However, if a query result is
     returned from query cache, the server increments the `Qcache_hits'
     status variable, not `Com_select'. See *Note
     query-cache-status-and-maintenance::.

     All of the `Com_stmt_XXX' variables are increased even if a
     prepared statement argument is unknown or an error occurred during
     execution. In other words, their values correspond to the number
     of requests issued, not to the number of requests successfully
     completed.

     The `Com_stmt_XXX' status variables are as follows:

        * `Com_stmt_prepare'

        * `Com_stmt_execute'

        * `Com_stmt_fetch'

        * `Com_stmt_send_long_data'

        * `Com_stmt_reset'

        * `Com_stmt_close'

     Those variables stand for prepared statement commands. Their names
     refer to the `COM_XXX' command set used in the network layer. In
     other words, their values increase whenever prepared statement API
     calls such as `mysql_stmt_prepare()', `mysql_stmt_execute()', and
     so forth are executed. However, `Com_stmt_prepare',
     `Com_stmt_execute' and `Com_stmt_close' also increase for *Note
     `PREPARE': prepare, *Note `EXECUTE': execute, or *Note `DEALLOCATE
     PREPARE': deallocate-prepare, respectively. Additionally, the
     values of the older (available since MySQL 4.1.3) statement
     counter variables `Com_prepare_sql', `Com_execute_sql', and
     `Com_dealloc_sql' increase for the *Note `PREPARE': prepare, *Note
     `EXECUTE': execute, and *Note `DEALLOCATE PREPARE':
     deallocate-prepare. statements.  `Com_stmt_fetch' stands for the
     total number of network round-trips issued when fetching from
     cursors.

     `Com_stmt_reprepare' indicated the number of times statements were
     automatically reprepared by the server after metadata changes to
     tables or views referred to by the statement. This variable was
     added in MySQL 6.0.6. A reprepare operation increments
     `Com_stmt_reprepare' is incremented, and also `Com_stmt_prepare'.

   *  `Compression'

     Whether the client connection uses compression in the
     client/server protocol.

   *  `Connections'

     The number of connection attempts (successful or not) to the MySQL
     server.

   *  `Created_tmp_disk_tables'

     The number of temporary tables on disk created automatically by
     the server while executing statements.

   *  `Created_tmp_files'

     How many temporary files *Note `mysqld': mysqld. has created.

   *  `Created_tmp_tables'

     The number of in-memory temporary tables created automatically by
     the server while executing statements. If
     `Created_tmp_disk_tables' is large, you may want to increase the
     `tmp_table_size' value to cause temporary tables to be
     memory-based instead of disk-based.

   *  `Delayed_errors'

     The number of rows written with *Note `INSERT DELAYED':
     insert-delayed. for which some error occurred (probably `duplicate
     key').

   *  `Delayed_insert_threads'

     The number of *Note `INSERT DELAYED': insert-delayed.  handler
     threads in use.

   *  `Delayed_writes'

     The number of *Note `INSERT DELAYED': insert-delayed.  rows
     written.

   *  `Flush_commands'

     The number of executed *Note `FLUSH': flush.  statements.

   *  `Handler_commit'

     The number of internal *Note `COMMIT': commit.  statements.

   *  `Handler_delete'

     The number of times that rows have been deleted from tables.

   *  `Handler_prepare'

     A counter for the prepare phase of two-phase commit operations.

   *  `Handler_read_first'

     The number of times the first entry was read from an index. If
     this value is high, it suggests that the server is doing a lot of
     full index scans; for example, `SELECT col1 FROM foo', assuming
     that `col1' is indexed.

   *  `Handler_read_key'

     The number of requests to read a row based on a key. If this value
     is high, it is a good indication that your tables are properly
     indexed for your queries.

   *  `Handler_read_next'

     The number of requests to read the next row in key order. This
     value is incremented if you are querying an index column with a
     range constraint or if you are doing an index scan.

   *  `Handler_read_prev'

     The number of requests to read the previous row in key order.
     This read method is mainly used to optimize `ORDER BY ... DESC'.

   *  `Handler_read_rnd'

     The number of requests to read a row based on a fixed position.
     This value is high if you are doing a lot of queries that require
     sorting of the result. You probably have a lot of queries that
     require MySQL to scan entire tables or you have joins that don't
     use keys properly.

   *  `Handler_read_rnd_next'

     The number of requests to read the next row in the data file.
     This value is high if you are doing a lot of table scans.
     Generally this suggests that your tables are not properly indexed
     or that your queries are not written to take advantage of the
     indexes you have.

   *  `Handler_rollback'

     The number of requests for a storage engine to perform a rollback
     operation.

   *  `Handler_savepoint'

     The number of requests for a storage engine to place a savepoint.

   *  `Handler_savepoint_rollback'

     The number of requests for a storage engine to roll back to a
     savepoint.

   *  `Handler_update'

     The number of requests to update a row in a table.

   *  `Handler_write'

     The number of requests to insert a row in a table.

   *  `Innodb_buffer_pool_pages_data'

     The number of pages containing data (dirty or clean).

   *  `Innodb_buffer_pool_pages_dirty'

     The number of pages currently dirty.

   *  `Innodb_buffer_pool_pages_flushed'

     The number of buffer pool page-flush requests.

   *  `Innodb_buffer_pool_pages_free'

     The number of free pages.

   *  `Innodb_buffer_pool_pages_latched'

     The number of latched pages in `InnoDB' buffer pool. These are
     pages currently being read or written or that cannot be flushed or
     removed for some other reason.  Calculation of this variable is
     expensive, so as of MySQL 6.0.6, it is available only when the
     `UNIV_DEBUG' system is defined at server build time.

   *  `Innodb_buffer_pool_pages_misc'

     The number of pages that are busy because they have been allocated
     for administrative overhead such as row locks or the adaptive hash
     index. This value can also be calculated as
     `Innodb_buffer_pool_pages_total' - `Innodb_buffer_pool_pages_free'
     - `Innodb_buffer_pool_pages_data'.

   *  `Innodb_buffer_pool_pages_total'

     The total size of the buffer pool, in pages.

   *  `Innodb_buffer_pool_read_ahead_rnd'

     The number of `random' read-aheads initiated by `InnoDB'. This
     happens when a query scans a large portion of a table but in
     random order.

   *  `Innodb_buffer_pool_read_ahead_seq'

     The number of sequential read-aheads initiated by `InnoDB'. This
     happens when `InnoDB' does a sequential full table scan.

   *  `Innodb_buffer_pool_read_requests'

     The number of logical read requests `InnoDB' has done.

   *  `Innodb_buffer_pool_reads'

     The number of logical reads that `InnoDB' could not satisfy from
     the buffer pool and had to do a single-page read.

   *  `Innodb_buffer_pool_wait_free'

     Normally, writes to the `InnoDB' buffer pool happen in the
     background. However, if it is necessary to read or create a page
     and no clean pages are available, it is also necessary to wait for
     pages to be flushed first. This counter counts instances of these
     waits. If the buffer pool size has been set properly, this value
     should be small.

   *  `Innodb_buffer_pool_write_requests'

     The number writes done to the `InnoDB' buffer pool.

   *  `Innodb_data_fsyncs'

     The number of `fsync()' operations so far.

   *  `Innodb_data_pending_fsyncs'

     The current number of pending `fsync()' operations.

   *  `Innodb_data_pending_reads'

     The current number of pending reads.

   *  `Innodb_data_pending_writes'

     The current number of pending writes.

   *  `Innodb_data_read'

     The amount of data read so far, in bytes.

   *  `Innodb_data_reads'

     The total number of data reads.

   *  `Innodb_data_writes'

     The total number of data writes.

   *  `Innodb_data_written'

     The amount of data written so far, in bytes.

   *  `Innodb_dblwr_pages_written'

     The number of pages that have been written for doublewrite
     operations. See *Note innodb-disk-io::.

   *  `Innodb_dblwr_writes'

     The number of doublewrite operations that have been performed.
     See *Note innodb-disk-io::.

   *  `Innodb_log_waits'

     The number of times that the log buffer was too small and a wait
     was required for it to be flushed before continuing.

   *  `Innodb_log_write_requests'

     The number of log write requests.

   *  `Innodb_log_writes'

     The number of physical writes to the log file.

   *  `Innodb_os_log_fsyncs'

     The number of `fsync()' writes done to the log file.

   *  `Innodb_os_log_pending_fsyncs'

     The number of pending log file `fsync()' operations.

   *  `Innodb_os_log_pending_writes'

     The number of pending log file writes.

   *  `Innodb_os_log_written'

     The number of bytes written to the log file.

   *  `Innodb_page_size'

     The compiled-in `InnoDB' page size (default 16KB). Many values are
     counted in pages; the page size allows them to be easily converted
     to bytes.

   *  `Innodb_pages_created'

     The number of pages created.

   *  `Innodb_pages_read'

     The number of pages read.

   *  `Innodb_pages_written'

     The number of pages written.

   *  `Innodb_row_lock_current_waits'

     The number of row locks currently being waited for.

   *  `Innodb_row_lock_time'

     The total time spent in acquiring row locks, in milliseconds.

   *  `Innodb_row_lock_time_avg'

     The average time to acquire a row lock, in milliseconds.

   *  `Innodb_row_lock_time_max'

     The maximum time to acquire a row lock, in milliseconds.

   *  `Innodb_row_lock_waits'

     The number of times a row lock had to be waited for.

   *  `Innodb_rows_deleted'

     The number of rows deleted from `InnoDB' tables.

   *  `Innodb_rows_inserted'

     The number of rows inserted into `InnoDB' tables.

   *  `Innodb_rows_read'

     The number of rows read from `InnoDB' tables.

   *  `Innodb_rows_updated'

     The number of rows updated in `InnoDB' tables.

   *  `Key_blocks_not_flushed'

     The number of key blocks in the key cache that have changed but
     have not yet been flushed to disk.

   *  `Key_blocks_unused'

     The number of unused blocks in the key cache. You can use this
     value to determine how much of the key cache is in use; see the
     discussion of `key_buffer_size' in *Note server-system-variables::.

   *  `Key_blocks_used'

     The number of used blocks in the key cache. This value is a
     high-water mark that indicates the maximum number of blocks that
     have ever been in use at one time.

   *  `Key_read_requests'

     The number of requests to read a key block from the cache.

   *  `Key_reads'

     The number of physical reads of a key block from disk. If
     `Key_reads' is large, then your `key_buffer_size' value is
     probably too small. The cache miss rate can be calculated as
     `Key_reads'/`Key_read_requests'.

   *  `Key_write_requests'

     The number of requests to write a key block to the cache.

   *  `Key_writes'

     The number of physical writes of a key block to disk.

   *  `Last_query_cost'

     The total cost of the last compiled query as computed by the query
     optimizer. This is useful for comparing the cost of different
     query plans for the same query. The default value of 0 means that
     no query has been compiled yet. The default value is 0.
     `Last_query_cost' has session scope.

     The `Last_query_cost' value can be computed accurately only for
     simple `flat' queries, not complex queries such as those with
     subqueries or *Note `UNION': union. For the latter, the value is
     set to 0.

   *  `Max_used_connections'

     The maximum number of connections that have been in use
     simultaneously since the server started.

   *  `Not_flushed_delayed_rows'

     The number of rows waiting to be written in `INSERT DELAY' queues.

   *  `Open_files'

     The number of files that are open. This count includes regular
     files opened by the server. It does not include other types of
     files such as sockets or pipes. Also, the count does not include
     files that storage engines open using their own internal functions
     rather than asking the server level to do so.

   *  `Open_streams'

     The number of streams that are open (used mainly for logging).

   *  `Open_table_definitions'

     The number of cached `.frm' files.

   *  `Open_tables'

     The number of tables that are open.

   *  `Opened_files'

     The number of files that have been opened with `my_open()' (a
     `mysys' library function). Parts of the server that open files
     without using this function do not increment the count.

   *  `Opened_table_definitions'

     The number of `.frm' files that have been cached. This variable
     was added in MySQL 6.0.4.

   *  `Opened_tables'

     The number of tables that have been opened. If `Opened_tables' is
     big, your `table_open_cache' value is probably too small.

   *  `Prepared_stmt_count'

     The current number of prepared statements. (The maximum number of
     statements is given by the `max_prepared_stmt_count' system
     variable.)

   *  `Qcache_free_blocks'

     The number of free memory blocks in the query cache.

   *  `Qcache_free_memory'

     The amount of free memory for the query cache.

   *  `Qcache_hits'

     The number of query cache hits.

   *  `Qcache_inserts'

     The number of queries added to the query cache.

   *  `Qcache_lowmem_prunes'

     The number of queries that were deleted from the query cache
     because of low memory.

   *  `Qcache_not_cached'

     The number of non-cached queries (not cacheable, or not cached due
     to the `query_cache_type' setting).

   *  `Qcache_queries_in_cache'

     The number of queries registered in the query cache.

   *  `Qcache_total_blocks'

     The total number of blocks in the query cache.

   *  `Queries'

     The number of statements executed by the server. This variable
     includes statements executed within stored programs, unlike the
     `Questions' variable. This variable was added in MySQL 6.0.10.

   *  `Questions'

     The number of statements executed by the server. As of MySQL
     6.0.6, this includes only statements sent to the server by clients
     and no longer includes statements executed within stored programs,
     unlike the `Queries' variable.

   *  `Rpl_semi_sync_master_clients'

     The number of semisynchronous slaves.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_net_avg_wait_time'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_net_wait_time'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_net_waits'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_no_times'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_no_tx'

     The number of commits that were not acknowledged successfully by a
     slave.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_status'

     Whether semisynchronous replication currently is operational on
     the master. The value is 1 if the plugin has been enabled and a
     commit acknowledgment has not occurred. It is 0 if the plugin is
     not enabled or the master has fallen back to asynchronous
     replication due to commit acknowledgment timeout.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_timefunc_failures'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_tx_avg_wait_time'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_tx_wait_time'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_tx_waits'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_wait_pos_backtraverse'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_wait_sessions'

     For internal use.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_master_yes_tx'

     The number of commits that were acknowledged successfully by a
     slave.

     This variable is was added in MySQL 6.0.8. It is available only if
     the master-side semisynchronous replication plugin is installed.

   *  `Rpl_semi_sync_slave_status'

     Whether semisynchronous replication currently is operational on
     the slave. This is 1 if the plugin has been enabled and the slave
     I/O thread is running, 0 otherwise.

     This variable is was added in MySQL 6.0.8. It is available only if
     the slave-side semisynchronous replication plugin is installed.

   *  `Rpl_status'

     The status of fail-safe replication (not yet implemented).

   *  `Select_full_join'

     The number of joins that perform table scans because they do not
     use indexes. If this value is not 0, you should carefully check
     the indexes of your tables.

   *  `Select_full_range_join'

     The number of joins that used a range search on a reference table.

   *  `Select_range'

     The number of joins that used ranges on the first table. This is
     normally not a critical issue even if the value is quite large.

   *  `Select_range_check'

     The number of joins without keys that check for key usage after
     each row. If this is not 0, you should carefully check the indexes
     of your tables.

   *  `Select_scan'

     The number of joins that did a full scan of the first table.

   *  `Slave_heartbeat_period'

     Shows the replication heartbeat interval (in seconds) on a
     replication slave.

     This variable was added in MySQL 6.0.4.

   *  `Slave_open_temp_tables'

     The number of temporary tables that the slave SQL thread currently
     has open.

   *  `Slave_received_heartbeats'

     This counter increments with each replication heartbeat received
     by a replication slave since the last time that the slave was
     restarted or reset, or a *Note `CHANGE MASTER TO':
     change-master-to. statement was issued.

     This variable was added in MySQL 6.0.4.

   *  `Slave_retried_transactions'

     The total number of times since startup that the replication slave
     SQL thread has retried transactions.

   *  `Slave_running'

     In MySQL 6.0.10 and earlier, this is `ON' if this server is a
     replication slave that is connected to a replication master, and
     both the I/O and SQL threads are running; otherwise, it is `OFF'.

     In MySQL 6.0.11 and later, this status variable takes on of 3
     values:

        * `ON', if this server is a slave that is connected to a
          replication master, and both the I/O SQL and threads are
          running

        * `OFF', if the slave I/O thread is not running

        * `CONNECTING', if the slave I/O thread is running, but this
          server is not connected to a replication master

     Also in MySQL 6.0.11 and later, the value of `Slave_running'
     corresponds with the value shown for `Slave_IO_running' in the
     output of *Note `SHOW SLAVE STATUS': show-slave-status, which was
     not always the case previously. (Bug#30703
     (http://bugs.mysql.com/30703))

   *  `Slow_launch_threads'

     The number of threads that have taken more than `slow_launch_time'
     seconds to create.

   *  `Slow_queries'

     The number of queries that have taken more than `long_query_time'
     seconds. See *Note slow-query-log::.

   *  `Sort_merge_passes'

     The number of merge passes that the sort algorithm has had to do.
     If this value is large, you should consider increasing the value
     of the `sort_buffer_size' system variable.

   *  `Sort_range'

     The number of sorts that were done using ranges.

   *  `Sort_rows'

     The number of sorted rows.

   *  `Sort_scan'

     The number of sorts that were done by scanning the table.

   *  `Ssl_accept_renegotiates'

     The number of negotiates needed to establish the connection.

   *  `Ssl_accepts'

     The number of accepted SSL connections.

   *  `Ssl_callback_cache_hits'

     The number of callback cache hits.

   *  `Ssl_cipher'

     The current SSL cipher (empty for non-SSL connections).

   *  `Ssl_cipher_list'

     The list of possible SSL ciphers.

   *  `Ssl_client_connects'

     The number of SSL connection attempts to an SSL-enabled master.

   *  `Ssl_connect_renegotiates'

     The number of negotiates needed to establish the connection to an
     SSL-enabled master.

   *  `Ssl_ctx_verify_depth'

     The SSL context verification depth (how many certificates in the
     chain are tested).

   *  `Ssl_ctx_verify_mode'

     The SSL context verification mode.

   *  `Ssl_default_timeout'

     The default SSL timeout.

   *  `Ssl_finished_accepts'

     The number of successful SSL connections to the server.

   *  `Ssl_finished_connects'

     The number of successful slave connections to an SSL-enabled
     master.

   *  `Ssl_session_cache_hits'

     The number of SSL session cache hits.

   *  `Ssl_session_cache_misses'

     The number of SSL session cache misses.

   *  `Ssl_session_cache_mode'

     The SSL session cache mode.

   *  `Ssl_session_cache_overflows'

     The number of SSL session cache overflows.

   *  `Ssl_session_cache_size'

     The SSL session cache size.

   *  `Ssl_session_cache_timeouts'

     The number of SSL session cache timeouts.

   *  `Ssl_sessions_reused'

     How many SSL connections were reused from the cache.

   *  `Ssl_used_session_cache_entries'

     How many SSL session cache entries were used.

   *  `Ssl_verify_depth'

     The verification depth for replication SSL connections.

   *  `Ssl_verify_mode'

     The verification mode for replication SSL connections.

   *  `Ssl_version'

     The SSL version number.

   *  `Table_locks_immediate'

     The number of times that a request for a table lock could be
     granted immediately.

   *  `Table_locks_waited'

     The number of times that a request for a table lock could not be
     granted immediately and a wait was needed. If this is high and you
     have performance problems, you should first optimize your queries,
     and then either split your table or tables or use replication.

   *  `Tc_log_max_pages_used'

     For the memory-mapped implementation of the log that is used by
     *Note `mysqld': mysqld. when it acts as the transaction
     coordinator for recovery of internal XA transactions, this
     variable indicates the largest number of pages used for the log
     since the server started. If the product of
     `Tc_log_max_pages_used' and `Tc_log_page_size' is always
     significantly less than the log size, the size is larger than
     necessary and can be reduced. (The size is set by the
     `--log-tc-size' option.  Currently, this variable is unused: It is
     unneeded for binary log-based recovery, and the memory-mapped
     recovery log method is not used unless the number of storage
     engines capable of two-phase commit is greater than one.
     (`InnoDB' is the only applicable engine.)

   *  `Tc_log_page_size'

     The page size used for the memory-mapped implementation of the XA
     recovery log. The default value is determined using
     `getpagesize()'. Currently, this variable is unused for the same
     reasons as described for `Tc_log_max_pages_used'.

   *  `Tc_log_page_waits'

     For the memory-mapped implementation of the recovery log, this
     variable increments each time the server was not able to commit a
     transaction and had to wait for a free page in the log. If this
     value is large, you might want to increase the log size (with the
     `--log-tc-size' option). For binary log-based recovery, this
     variable increments each time the binary log cannot be closed
     because there are two-phase commits in progress. (The close
     operation waits until all such transactions are finished.)

   *  `Threads_cached'

     The number of threads in the thread cache.

   *  `Threads_connected'

     The number of currently open connections.

   *  `Threads_created'

     The number of threads created to handle connections. If
     `Threads_created' is big, you may want to increase the
     `thread_cache_size' value. The cache miss rate can be calculated as
     `Threads_created'/`Connections'.

   *  `Threads_running'

     The number of threads that are not sleeping.

   *  `Uptime'

     The number of seconds that the server has been up.

   *  `Uptime_since_flush_status'

     The number of seconds since the most recent `FLUSH STATUS'
     statement. This variable was added in 6.0.5.


File: manual.info,  Node: server-sql-mode,  Next: server-side-help-support,  Prev: server-status-variables,  Up: mysqld-server

5.1.7 Server SQL Modes
----------------------

The MySQL server can operate in different SQL modes, and can apply
these modes differently for different clients. This capability enables
each application to tailor the server's operating mode to its own
requirements.

For answers to some questions that are often asked about server SQL
modes in MySQL, see *Note faqs-sql-modes::.

Modes define what SQL syntax MySQL should support and what kind of data
validation checks it should perform. This makes it easier to use MySQL
in different environments and to use MySQL together with other database
servers.

You can set the default SQL mode by starting *Note `mysqld': mysqld.
with the `--sql-mode="MODES"' option, or by using `sql-mode="MODES"' in
`my.cnf' (Unix operating systems) or `my.ini' (Windows).  MODES is a
list of different modes separated by comma (``,'') characters. The
default value is empty (no modes set). The MODES value also can be empty
(`--sql-mode=""' on the command line, or `sql-mode=""' in `my.cnf' on
Unix systems or in `my.ini' on Windows) if you want to clear it
explicitly.

You can change the SQL mode at runtime by using a `SET [GLOBAL|SESSION]
sql_mode='MODES'' statement to set the `sql_mode' system value.
Setting the `GLOBAL' variable requires the `SUPER' privilege and
affects the operation of all clients that connect from that time on.
Setting the `SESSION' variable affects only the current client. Any
client can change its own session `sql_mode' value at any time.

*Important*:

SQL mode and user-defined partitioning

Changing the server SQL mode after creating and inserting data into
partitioned tables can cause major changes in the behavior of such
tables, and could lead to loss or corruption of data. It is strongly
recommended that you never change the SQL mode once you have created
tables employing user-defined partitioning.

See *Note partitioning-limitations::, for more information.

You can retrieve the current global or session `sql_mode' value with
the following statements:

     SELECT @@GLOBAL.sql_mode;
     SELECT @@SESSION.sql_mode;

The most important `sql_mode' values are probably these:

   * `ANSI'

     This mode changes syntax and behavior to conform more closely to
     standard SQL.

   * `STRICT_TRANS_TABLES'

     If a value could not be inserted as given into a transactional
     table, abort the statement. For a non-transactional table, abort
     the statement if the value occurs in a single-row statement or the
     first row of a multiple-row statement. More detail is given later
     in this section.

   * `TRADITIONAL'

     Make MySQL behave like a `traditional' SQL database system. A
     simple description of this mode is `give an error instead of a
     warning' when inserting an incorrect value into a column.

     *Note*:

     The *Note `INSERT': insert./*Note `UPDATE': update.  aborts as
     soon as the error is noticed. This may not be what you want if you
     are using a non-transactional storage engine, because data changes
     made prior to the error may not be rolled back, resulting in a
     `partially done' update.

When this manual refers to `strict mode,' it means a mode where at
least one of `STRICT_TRANS_TABLES' or `STRICT_ALL_TABLES' is enabled.

The following list describes all supported modes:

   *  `ALLOW_INVALID_DATES'

     Don't do full checking of dates. Check only that the month is in
     the range from 1 to 12 and the day is in the range from 1 to 31.
     This is very convenient for Web applications where you obtain
     year, month, and day in three different fields and you want to
     store exactly what the user inserted (without date validation).
     This mode applies to *Note `DATE': datetime. and *Note `DATETIME':
     datetime. columns. It does not apply *Note `TIMESTAMP': datetime.
     columns, which always require a valid date.

     The server requires that month and day values be legal, and not
     merely in the range 1 to 12 and 1 to 31, respectively.  With
     strict mode disabled, invalid dates such as `'2004-04-31'' are
     converted to `'0000-00-00'' and a warning is generated.  With
     strict mode enabled, invalid dates generate an error. To allow
     such dates, enable `ALLOW_INVALID_DATES'.

   *  `ANSI_QUOTES'

     Treat ``"'' as an identifier quote character (like the ```'' quote
     character) and not as a string quote character. You can still use
     ```'' to quote identifiers with this mode enabled. With
     `ANSI_QUOTES' enabled, you cannot use double quotes to quote
     literal strings, because it is interpreted as an identifier.

   *  `ERROR_FOR_DIVISION_BY_ZERO'

     Produce an error in strict mode (otherwise a warning) when a
     division by zero (or `MOD(X,0)') occurs during an *Note `INSERT':
     insert. or *Note `UPDATE': update. If this mode is not enabled,
     MySQL instead returns `NULL' for divisions by zero. For `INSERT
     IGNORE' or `UPDATE IGNORE', MySQL generates a warning for
     divisions by zero, but the result of the operation is `NULL'.

   *  `HIGH_NOT_PRECEDENCE'

     The precedence of the `NOT' operator is such that expressions such
     as `NOT a BETWEEN b AND c' are parsed as `NOT (a BETWEEN b AND
     c)'. In some older versions of MySQL, the expression was parsed as
     `(NOT a) BETWEEN b AND c'. The old higher-precedence behavior can
     be obtained by enabling the `HIGH_NOT_PRECEDENCE' SQL mode.

          mysql> SET sql_mode = '';
          mysql> SELECT NOT 1 BETWEEN -5 AND 5;
                  -> 0
          mysql> SET sql_mode = 'HIGH_NOT_PRECEDENCE';
          mysql> SELECT NOT 1 BETWEEN -5 AND 5;
                  -> 1

   *  `IGNORE_SPACE'

     Allow spaces between a function name and the ``('' character. This
     causes built-in function names to be treated as reserved words. As
     a result, identifiers that are the same as function names must be
     quoted as described in *Note identifiers::. For example, because
     there is a `COUNT()' function, the use of `count' as a table name
     in the following statement causes an error:

          mysql> CREATE TABLE count (i INT);
          ERROR 1064 (42000): You have an error in your SQL syntax

     The table name should be quoted:

          mysql> CREATE TABLE `count` (i INT);
          Query OK, 0 rows affected (0.00 sec)

     The `IGNORE_SPACE' SQL mode applies to built-in functions, not to
     user-defined functions or stored functions. It is always allowable
     to have spaces after a UDF or stored function name, regardless of
     whether `IGNORE_SPACE' is enabled.

     For further discussion of `IGNORE_SPACE', see *Note
     function-resolution::.

   *  `NO_AUTO_CREATE_USER'

     Prevent the *Note `GRANT': grant. statement from automatically
     creating new users if it would otherwise do so, unless a non-empty
     password also is specified.

   *  `NO_AUTO_VALUE_ON_ZERO'

     `NO_AUTO_VALUE_ON_ZERO' affects handling of `AUTO_INCREMENT'
     columns.  Normally, you generate the next sequence number for the
     column by inserting either `NULL' or `0' into it.
     `NO_AUTO_VALUE_ON_ZERO' suppresses this behavior for `0' so that
     only `NULL' generates the next sequence number.

     This mode can be useful if `0' has been stored in a table's
     `AUTO_INCREMENT' column.  (Storing `0' is not a recommended
     practice, by the way.) For example, if you dump the table with
     *Note `mysqldump': mysqldump. and then reload it, MySQL normally
     generates new sequence numbers when it encounters the `0' values,
     resulting in a table with contents different from the one that was
     dumped. Enabling `NO_AUTO_VALUE_ON_ZERO' before reloading the dump
     file solves this problem.  *Note `mysqldump': mysqldump. now
     automatically includes in its output a statement that enables
     `NO_AUTO_VALUE_ON_ZERO', to avoid this problem.

   *  `NO_BACKSLASH_ESCAPES'

     Disable the use of the backslash character (``\'') as an escape
     character within strings. With this mode enabled, backslash
     becomes an ordinary character like any other.

   *  `NO_DIR_IN_CREATE'

     When creating a table, ignore all `INDEX DIRECTORY' and `DATA
     DIRECTORY' directives. This option is useful on slave replication
     servers.

   *  `NO_ENGINE_SUBSTITUTION'

     Control automatic substitution of the default storage engine when
     a statement such as *Note `CREATE TABLE': create-table. or *Note
     `ALTER TABLE': alter-table.  specifies a storage engine that is
     disabled or not compiled in.

     Because storage engines can be pluggable at runtime, unavailable
     engines are treated the same way:

     With `NO_ENGINE_SUBSTITUTION' disabled, for *Note `CREATE TABLE':
     create-table. the default engine is used and a warning occurs if
     the desired engine is unavailable. For *Note `ALTER TABLE':
     alter-table, a warning occurs and the table is not altered.

     With `NO_ENGINE_SUBSTITUTION' enabled, an error occurs and the
     table is not created or altered if the desired engine is
     unavailable.

   *  `NO_FIELD_OPTIONS'

     Do not print MySQL-specific column options in the output of *Note
     `SHOW CREATE TABLE': show-create-table. This mode is used by *Note
     `mysqldump': mysqldump. in portability mode.

   *  `NO_KEY_OPTIONS'

     Do not print MySQL-specific index options in the output of *Note
     `SHOW CREATE TABLE': show-create-table. This mode is used by *Note
     `mysqldump': mysqldump. in portability mode.

   *  `NO_TABLE_OPTIONS'

     Do not print MySQL-specific table options (such as `ENGINE') in
     the output of *Note `SHOW CREATE TABLE': show-create-table. This
     mode is used by *Note `mysqldump': mysqldump. in portability mode.

   *  `NO_UNSIGNED_SUBTRACTION'

     In integer subtraction operations, do not mark the result as
     `UNSIGNED' if one of the operands is unsigned. In other words,
     _the result of a subtraction is always signed whenever this mode
     is in effect, even if one of the operands is unsigned_. For
     example, compare the type of column `c2' in table `t1' with that
     of column `c2' in table `t2':

          mysql> SET SQL_MODE='';
          mysql> CREATE TABLE test (c1 BIGINT UNSIGNED NOT NULL);
          mysql> CREATE TABLE t1 SELECT c1 - 1 AS c2 FROM test;
          mysql> DESCRIBE t1;
          +-------+---------------------+------+-----+---------+-------+
          | Field | Type                | Null | Key | Default | Extra |
          +-------+---------------------+------+-----+---------+-------+
          | c2    | bigint(21) unsigned |      |     | 0       |       |
          +-------+---------------------+------+-----+---------+-------+

          mysql> SET SQL_MODE='NO_UNSIGNED_SUBTRACTION';
          mysql> CREATE TABLE t2 SELECT c1 - 1 AS c2 FROM test;
          mysql> DESCRIBE t2;
          +-------+------------+------+-----+---------+-------+
          | Field | Type       | Null | Key | Default | Extra |
          +-------+------------+------+-----+---------+-------+
          | c2    | bigint(21) |      |     | 0       |       |
          +-------+------------+------+-----+---------+-------+

     Note that this means that `BIGINT UNSIGNED' is not 100% usable in
     all contexts. See *Note cast-functions::.

          mysql> SET SQL_MODE = '';
          mysql> SELECT CAST(0 AS UNSIGNED) - 1;
          +-------------------------+
          | CAST(0 AS UNSIGNED) - 1 |
          +-------------------------+
          |    18446744073709551615 |
          +-------------------------+

          mysql> SET SQL_MODE = 'NO_UNSIGNED_SUBTRACTION';
          mysql> SELECT CAST(0 AS UNSIGNED) - 1;
          +-------------------------+
          | CAST(0 AS UNSIGNED) - 1 |
          +-------------------------+
          |                      -1 |
          +-------------------------+

   *  `NO_ZERO_DATE'

     In strict mode, don't allow `'0000-00-00'' as a valid date. You
     can still insert zero dates with the `IGNORE' option. When not in
     strict mode, the date is accepted but a warning is generated.

   *  `NO_ZERO_IN_DATE'

     In strict mode, do not accept dates where the year part is
     non-zero but the month or day part is 0 (for example,
     `'0000-00-00'' is legal but `'2010-00-01'' and `'2010-01-00'' are
     not). If used with the `IGNORE' option, MySQL inserts a
     `'0000-00-00'' date for any such date. When not in strict mode,
     the date is accepted but a warning is generated.

   *  `ONLY_FULL_GROUP_BY'

     Do not allow queries for which the *Note `SELECT': select. list
     refers to non-aggregated columns that are not named in the `GROUP
     BY' clause. The following query is invalid with this mode enabled
     because `address' is not named in the `GROUP BY' clause:

          SELECT name, address, MAX(age) FROM t GROUP BY name;

     This mode also restricts references to non-aggregated columns in
     the `HAVING' clause that are not named in the `GROUP BY' clause.

   *  `PAD_CHAR_TO_FULL_LENGTH'

     By default, trailing spaces are trimmed from *Note `CHAR': char.
     column values on retrieval. If `PAD_CHAR_TO_FULL_LENGTH' is
     enabled, trimming does not occur and retrieved *Note `CHAR': char.
     values are padded to their full length. This mode does not apply to
     *Note `VARCHAR': char. columns, for which trailing spaces are
     retained on retrieval.

          mysql> CREATE TABLE t1 (c1 CHAR(10));
          Query OK, 0 rows affected (0.37 sec)

          mysql> INSERT INTO t1 (c1) VALUES('xy');
          Query OK, 1 row affected (0.01 sec)

          mysql> SET sql_mode = '';
          Query OK, 0 rows affected (0.00 sec)

          mysql> SELECT c1, CHAR_LENGTH(c1) FROM t1;
          +------+-----------------+
          | c1   | CHAR_LENGTH(c1) |
          +------+-----------------+
          | xy   |               2 |
          +------+-----------------+
          1 row in set (0.00 sec)

          mysql> SET sql_mode = 'PAD_CHAR_TO_FULL_LENGTH';
          Query OK, 0 rows affected (0.00 sec)

          mysql> SELECT c1, CHAR_LENGTH(c1) FROM t1;
          +------------+-----------------+
          | c1         | CHAR_LENGTH(c1) |
          +------------+-----------------+
          | xy         |              10 |
          +------------+-----------------+
          1 row in set (0.00 sec)

   *  `PIPES_AS_CONCAT'

     Treat `||' as a string concatenation operator (same as `CONCAT()')
     rather than as a synonym for `OR'.

   *  `REAL_AS_FLOAT'

     Treat *Note `REAL': numeric-types. as a synonym for *Note `FLOAT':
     numeric-types. By default, MySQL treats *Note `REAL':
     numeric-types. as a synonym for *Note `DOUBLE': numeric-types.

   *  `STRICT_ALL_TABLES'

     Enable strict mode for all storage engines. Invalid data values
     are rejected. Additional detail follows.

   *  `STRICT_TRANS_TABLES'

     Enable strict mode for transactional storage engines, and when
     possible for non-transactional storage engines. Additional details
     follow.

Strict mode controls how MySQL handles input values that are invalid or
missing. A value can be invalid for several reasons.  For example, it
might have the wrong data type for the column, or it might be out of
range. A value is missing when a new row to be inserted does not
contain a value for a non-`NULL' column that has no explicit `DEFAULT'
clause in its definition. (For a `NULL' column, `NULL' is inserted if
the value is missing.)

For transactional tables, an error occurs for invalid or missing values
in a statement when either of the `STRICT_ALL_TABLES' or
`STRICT_TRANS_TABLES' modes are enabled. The statement is aborted and
rolled back.

For non-transactional tables, the behavior is the same for either mode,
if the bad value occurs in the first row to be inserted or updated. The
statement is aborted and the table remains unchanged.  If the statement
inserts or modifies multiple rows and the bad value occurs in the
second or later row, the result depends on which strict option is
enabled:

   * For `STRICT_ALL_TABLES', MySQL returns an error and ignores the
     rest of the rows. However, in this case, the earlier rows still
     have been inserted or updated. This means that you might get a
     partial update, which might not be what you want. To avoid this,
     it is best to use single-row statements because these can be
     aborted without changing the table.

   * For `STRICT_TRANS_TABLES', MySQL converts an invalid value to the
     closest valid value for the column and insert the adjusted value.
     If a value is missing, MySQL inserts the implicit default value
     for the column data type. In either case, MySQL generates a warning
     rather than an error and continues processing the statement.
     Implicit defaults are described in *Note data-type-defaults::.

Strict mode disallows invalid date values such as `'2004-04-31''. It
does not disallow dates with zero month or day parts such as
`'2004-04-00'' or `zero' dates. To disallow these as well, enable the
`NO_ZERO_IN_DATE' and `NO_ZERO_DATE' SQL modes in addition to strict
mode.

If you are not using strict mode (that is, neither
`STRICT_TRANS_TABLES' nor `STRICT_ALL_TABLES' is enabled), MySQL
inserts adjusted values for invalid or missing values and produces
warnings. In strict mode, you can produce this behavior by using
`INSERT IGNORE' or `UPDATE IGNORE'. See *Note show-warnings::.

Strict mode does not affect whether foreign key constraints are
checked. `foreign_key_checks' can be used for that. (See *Note
server-session-variables::.)

The following special modes are provided as shorthand for combinations
of mode values from the preceding list.

The descriptions include all mode values that are available in the most
recent version of MySQL. For older versions, a combination mode does
not include individual mode values that are not available except in
newer versions.

   *  `ANSI'

     Equivalent to `REAL_AS_FLOAT', `PIPES_AS_CONCAT', `ANSI_QUOTES',
     `IGNORE_SPACE'.

     `ANSI' mode causes the server to return an error for queries where
     a set function S with an outer reference `S(OUTER_REF)' cannot be
     aggregated in the outer query against which the outer reference
     has been resolved. This is such a query:

          SELECT * FROM t1 WHERE t1.a IN (SELECT MAX(t1.b) FROM t2 WHERE ...);

     Here, `MAX(t1.b)' cannot aggregated in the outer query because it
     appears in the `WHERE' clause of that query. Standard SQL requires
     an error in this situation. If `ANSI' mode is not enabled, the
     server treats `S(OUTER_REF)' in such queries the same way that it
     would interpret `S(CONST)'.

     See *Note ansi-mode::.

   *  `DB2'

     Equivalent to `PIPES_AS_CONCAT', `ANSI_QUOTES', `IGNORE_SPACE',
     `NO_KEY_OPTIONS', `NO_TABLE_OPTIONS', `NO_FIELD_OPTIONS'.

   *  `MAXDB'

     Equivalent to `PIPES_AS_CONCAT', `ANSI_QUOTES', `IGNORE_SPACE',
     `NO_KEY_OPTIONS', `NO_TABLE_OPTIONS', `NO_FIELD_OPTIONS',
     `NO_AUTO_CREATE_USER'.

   *  `MSSQL'

     Equivalent to `PIPES_AS_CONCAT', `ANSI_QUOTES', `IGNORE_SPACE',
     `NO_KEY_OPTIONS', `NO_TABLE_OPTIONS', `NO_FIELD_OPTIONS'.

   *  `MYSQL323'

     Equivalent to `NO_FIELD_OPTIONS', `HIGH_NOT_PRECEDENCE'.

   *  `MYSQL40'

     Equivalent to `NO_FIELD_OPTIONS', `HIGH_NOT_PRECEDENCE'.

   *  `ORACLE'

     Equivalent to `PIPES_AS_CONCAT', `ANSI_QUOTES', `IGNORE_SPACE',
     `NO_KEY_OPTIONS', `NO_TABLE_OPTIONS', `NO_FIELD_OPTIONS',
     `NO_AUTO_CREATE_USER'.

   *  `POSTGRESQL'

     Equivalent to `PIPES_AS_CONCAT', `ANSI_QUOTES', `IGNORE_SPACE',
     `NO_KEY_OPTIONS', `NO_TABLE_OPTIONS', `NO_FIELD_OPTIONS'.

   *  `TRADITIONAL'

     Equivalent to `STRICT_TRANS_TABLES', `STRICT_ALL_TABLES',
     `NO_ZERO_IN_DATE', `NO_ZERO_DATE', `ERROR_FOR_DIVISION_BY_ZERO',
     `NO_AUTO_CREATE_USER'.


File: manual.info,  Node: server-side-help-support,  Next: server-signal-response,  Prev: server-sql-mode,  Up: mysqld-server

5.1.8 Server-Side Help
----------------------

MySQL Server supports a *Note `HELP': help.  statement that returns
online information from the MySQL Reference manual (see *Note help::).
The proper operation of this statement requires that the help tables in
the `mysql' database be initialized with help topic information, which
is done by processing the contents of the `fill_help_tables.sql' script.

For a MySQL binary distribution on Unix, help table setup occurs when
you run *Note `mysql_install_db': mysql-install-db. For an RPM
distribution on Linux or binary distribution on Windows, help table
setup occurs as part of the MySQL installation process.

For a MySQL source distribution, you can find the
`fill_help_tables.sql' file in the `scripts' directory. To load the
file manually, make sure that you have initialized the `mysql' database
by running *Note `mysql_install_db': mysql-install-db, and then process
the file with the *Note `mysql': mysql. client as follows:

     shell> mysql -u root mysql < fill_help_tables.sql

If you are working with Bazaar and a MySQL development source tree, the
tree doesn't contain `fill_help_tables.sql'. You can download the
proper file for your version of MySQL from `http://dev.mysql.com/doc/'.
After downloading and uncompressing the file, process it with *Note
`mysql': mysql.  as just described.


File: manual.info,  Node: server-signal-response,  Next: server-shutdown,  Prev: server-side-help-support,  Up: mysqld-server

5.1.9 Server Response to Signals
--------------------------------

On Unix, signals can be sent to processes.  *Note `mysqld': mysqld.
responds to signals sent to it as follows:

   * `SIGTERM' causes the server to shut down.

   * `SIGHUP' causes the server to reload the grant tables and flush
     the logs (like *Note `FLUSH PRIVILEGES': flush. and *Note `FLUSH
     LOGS': flush.).  It also writes a status report to the error log
     that has this format:

          Status information:

          Current dir: /var/mysql/data/
          Running threads: 0  Stack size: 196608
          Current locks:

          Key caches:
          default
          Buffer_size:       8388600
          Block_size:           1024
          Division_limit:        100
          Age_limit:             300
          blocks used:             0
          not flushed:             0
          w_requests:              0
          writes:                  0
          r_requests:              0
          reads:                   0

          handler status:
          read_key:            0
          read_next:           0
          read_rnd             0
          read_first:          1
          write:               0
          delete               0
          update:              0

          Table status:
          Opened tables:          5
          Open tables:            0
          Open files:             7
          Open streams:           0

          Alarm status:
          Active alarms:   1
          Max used alarms: 2
          Next alarm time: 67

On some Mac OS X 10.3 versions, *Note `mysqld': mysqld. ignores
`SIGHUP' and `SIGQUIT'.


File: manual.info,  Node: server-shutdown,  Prev: server-signal-response,  Up: mysqld-server

5.1.10 The Shutdown Process
---------------------------

The server shutdown process takes place as follows:

  1. The shutdown process is initiated.

     Server shutdown can be initiated several ways. For example, a user
     with the `SHUTDOWN' privilege can execute a *Note `mysqladmin
     shutdown': mysqladmin.  command. *Note `mysqladmin': mysqladmin.
     can be used on any platform supported by MySQL. Other operating
     system-specific shutdown initiation methods are possible as well:
     The server shuts down on Unix when it receives a `SIGTERM' signal.
     A server running as a service on Windows shuts down when the
     services manager tells it to.

  2. The server creates a shutdown thread if necessary.

     Depending on how shutdown was initiated, the server might create a
     thread to handle the shutdown process. If shutdown was requested
     by a client, a shutdown thread is created. If shutdown is the
     result of receiving a `SIGTERM' signal, the signal thread might
     handle shutdown itself, or it might create a separate thread to do
     so. If the server tries to create a shutdown thread and cannot
     (for example, if memory is exhausted), it issues a diagnostic
     message that appears in the error log:

          Error: Can't create thread to kill server

  3. The server stops accepting new connections.

     To prevent new activity from being initiated during shutdown, the
     server stops accepting new client connections. It does this by
     closing the network connections to which it normally listens for
     connections: the TCP/IP port, the Unix socket file, the Windows
     named pipe, and shared memory on Windows.

  4. The server terminates current activity.

     For each thread that is associated with a client connection, the
     connection to the client is broken and the thread is marked as
     killed. Threads die when they notice that they are so marked.
     Threads for idle connections die quickly. Threads that currently
     are processing statements check their state periodically and take
     longer to die. For additional information about thread
     termination, see *Note kill::, in particular for the instructions
     about killed *Note `REPAIR TABLE': repair-table. or *Note
     `OPTIMIZE TABLE': optimize-table. operations on `MyISAM' tables.

     For threads that have an open transaction, the transaction is
     rolled back. Note that if a thread is updating a non-transactional
     table, an operation such as a multiple-row *Note `UPDATE': update.
     or *Note `INSERT': insert. may leave the table partially updated,
     because the operation can terminate before completion.

     If the server is a master replication server, threads associated
     with currently connected slaves are treated like other client
     threads. That is, each one is marked as killed and exits when it
     next checks its state.

     If the server is a slave replication server, the I/O and SQL
     threads, if active, are stopped before client threads are marked
     as killed. The SQL thread is allowed to finish its current
     statement (to avoid causing replication problems), and then stops.
     If the SQL thread was in the middle of a transaction at this
     point, the transaction is rolled back.

  5. Storage engines are shut down or closed.

     At this stage, the table cache is flushed and all open tables are
     closed.

     Each storage engine performs any actions necessary for tables that
     it manages. For example, `MyISAM' flushes any pending index writes
     for a table.  `InnoDB' flushes its buffer pool to disk, unless
     `innodb_fast_shutdown' is 2, writes the current LSN to the
     tablespace, and terminates its own internal threads.

  6. The server exits.


File: manual.info,  Node: server-logs,  Next: security,  Prev: mysqld-server,  Up: server-administration

5.2 MySQL Server Logs
=====================

* Menu:

* log-tables::                   Selecting General Query and Slow Query Log Output Destinations
* error-log::                    The Error Log
* query-log::                    The General Query Log
* binary-log::                   The Binary Log
* slow-query-log::               The Slow Query Log
* log-file-maintenance::         Server Log Maintenance

MySQL has several different logs that can help you find out what is
going on inside *Note `mysqld': mysqld.

*Log Type*             *Information Written to Log*
The error log          Problems encountered starting, running, or
                       stopping *Note `mysqld': mysqld.
The general query log  Established client connections and statements
                       received from clients
The binary log         All statements that change data (also used for
                       replication)
The slow query log     All queries that took more than `long_query_time'
                       seconds to execute or didn't use indexes

By default, all log files are created in the *Note `mysqld': mysqld.
data directory. You can force *Note `mysqld': mysqld. to close and
reopen the log files (or in some cases switch to a new log) by flushing
the logs. Log flushing occurs when you issue a *Note `FLUSH LOGS':
flush. statement or execute *Note `mysqladmin flush-logs': mysqladmin.
or *Note `mysqladmin refresh': mysqladmin. See *Note flush::, and *Note
mysqladmin::.

If you are using MySQL replication capabilities, slave replication
servers maintain additional log files called relay logs.  *Note
replication::, discusses relay log contents and configuration.

The server can write general query and slow query entries to log
tables, log files, or both. For details, see *Note log-tables::.

You can also control during runtime the general query and slow query
logs. You can enable or disable logging, or change the name of the log
file. See *Note query-log::, and *Note slow-query-log::.

See *Note password-security-admin::, for information about keeping logs
secure.

MySQL Enterprise

The MySQL Enterprise Monitor provides a number of advisors specifically
related to the various log files. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: log-tables,  Next: error-log,  Prev: server-logs,  Up: server-logs

5.2.1 Selecting General Query and Slow Query Log Output Destinations
--------------------------------------------------------------------

MySQL Server provides flexible control over the destination for log
output. Log entries can be written to log files or to the `general_log'
and `slow_log' tables in the `mysql' database. If logging is enabled,
either or both destinations can be selected.

*Note*:

The log tables are created during the installation procedure along with
the other system tables. If you upgrade MySQL from a release older than
5.1.6 to MySQL 5.1.6 or higher, you must upgrade the system tables
after upgrading to make sure that the log tables exist. See *Note
mysql-upgrade::.

Currently, logging to tables incurs significantly more server overhead
than logging to files. If you enable the general log or slow query log
and require highest performance, you should log to files and not to
tables.

*Log control at server startup.* The `--log-output' option specifies
the destination for log output, if logging is enabled, but the option
does not in itself enable the logs. The syntax for this option is
`--log-output[=VALUE,...]':

   * If `--log-output' is given with a value, the value can be a
     comma-separated list of one or more of the words `TABLE' (log to
     tables), `FILE' (log to files), or `NONE' (do not log to tables or
     files).  `NONE', if present, takes precedence over any other
     specifiers.

   * If `--log-output' is omitted or given without a value, the default
     is `FILE'.

The `--general_log' option, if given, enables logging to the general
query log for the selected log destinations. `--general_log' takes an
optional argument of 1 or 0 to enable or disable the log. To specify a
file name other than the default for file logging, use
`--general_log_file=FILE_NAME'.  Similarly, the `--slow_query_log'
option, if given, enables logging to the slow query log for the
selected destinations and `--slow_query_log_file=FILE_NAME' specifies a
file name for file logging. If either log is enabled, the server opens
the corresponding log file and writes startup messages to it. However,
logging of queries to the file does not occur unless the `FILE' log
destination is selected. Prior to MySQL 6.0.8, the `--log' and
`--log-slow-queries' options enable the general query log and slow
query log. Either option may be given with a file name argument to
specify a log file name to override the default.

Examples:

   * To write general query log entries to the log table and the log
     file, use `--log-output=TABLE,FILE' to select both log
     destinations and the `--general_log' option to enable the general
     query log.

   * To write general and slow query log entries only to the log
     tables, use `--log-output=TABLE' to select tables as the log
     destination and the `--general_log' and `--slow_query_log' options
     to enable both logs.

   * To write slow query log entries only to the log file, use
     `--log-output=FILE' to select files as the log destination and the
     `--slow_query_log' option to enable the slow query log. (In this
     case, because the default log destination is `FILE', you could
     omit the `--log-output' option.)

*Log control at runtime.* Several system variables are associated with
log tables and files and enable runtime control over logging:

   * The global `log_output' system variable indicates the current
     logging destination. It can be modified at runtime to change the
     destination.

   * The global `general_log' and `slow_query_log' variables indicate
     whether the general query log and slow query log are enabled
     (`ON') or disabled (`OFF'). You can set these variables at runtime
     to control whether the logs are enabled.

   * The global `general_log_file' and `slow_query_log_file' variables
     indicate the names of the general query log and slow query log
     files. As of MySQL 6.0.8, you can set these variables at server
     startup or at runtime to change the names of the log files.
     (Before MySQL 6.0.8, you can set these variables only at runtime,
     but the the `--log' and `--log-slow-queries' options can be given
     with a file name argument at startup to change the log file names
     from their default values.)

   * The session `sql_log_off' variable can be set to `ON' or `OFF' to
     disable or enable general query logging for the current connection.

The use of tables for log output offers the following benefits:

   * Log entries have a standard format. To display the current
     structure of the log tables, use these statements:

          SHOW CREATE TABLE mysql.general_log;
          SHOW CREATE TABLE mysql.slow_log;

   * Log contents are accessible via SQL statements. This enables the
     use of queries that select only those log entries that satisfy
     specific criteria. For example, to select log contents associated
     with a particular client (which can be useful for identifying
     problematic queries from that client), it is easier to do this
     using a log table than a log file.

   * Logs are accessible remotely through any client that can connect
     to the server and issue queries (if the client has the appropriate
     log table privileges). It is not necessary to log in to the server
     host and directly access the file system.

The log table implementation has the following characteristics:

   * In general, the primary purpose of log tables is to provide an
     interface for users to observe the runtime execution of the
     server, not to interfere with its runtime execution.

   * *Note `CREATE TABLE': create-table, *Note `ALTER TABLE':
     alter-table, and *Note `DROP TABLE': drop-table. are valid
     operations on a log table. For *Note `ALTER TABLE': alter-table.
     and *Note `DROP TABLE': drop-table, the log table cannot be in use
     and must be disabled, as described later.

   * By default, the log tables use the `CSV' storage engine that
     writes data in comma-separated values format. For users who have
     access to the `.CSV' files that contain log table data, the files
     are easy to import into other programs such as spreadsheets that
     can process CSV input.

     The log tables can be altered to use the `MyISAM' storage engine.
     You cannot use *Note `ALTER TABLE': alter-table. to alter a log
     table that is in use. The log must be disabled first. No engines
     other than `CSV' or `MyISAM' are legal for the log tables.

   * To disable logging so that you can alter (or drop) a log table,
     you can use the following strategy. The example uses the general
     query log; the procedure for the slow query log is similar but
     uses the `slow_log' table and `slow_query_log' system variable.

          SET @old_log_state = @@global.general_log;
          SET GLOBAL general_log = 'OFF';
          ALTER TABLE mysql.general_log ENGINE = MyISAM;
          SET GLOBAL general_log = @old_log_state;

   * *Note `TRUNCATE TABLE': truncate. is a valid operation on a log
     table. It can be used to expire log entries.

   * *Note `RENAME TABLE': rename-table. is a valid operation on a log
     table. You can atomically rename a log table (to perform log
     rotation, for example) using the following strategy:

          USE mysql;
          CREATE TABLE IF NOT EXISTS general_log2 LIKE general_log;
          RENAME TABLE general_log TO general_log_backup, general_log2 TO general_log;

   * *Note `LOCK TABLES': lock-tables. cannot be used on a log table.

   * *Note `INSERT': insert, *Note `DELETE': delete, and *Note
     `UPDATE': update. cannot be used on a log table. These operations
     are allowed only internally to the server itself.

   * *Note `FLUSH TABLES WITH READ LOCK': flush. and the state of the
     global `read_only' system variable have no effect on log tables.
     The server can always write to the log tables.

   * Entries written to the log tables are not written to the binary
     log and thus are not replicated to slave servers.

   * To flush the log tables or log files, use *Note `FLUSH TABLES':
     flush.  or *Note `FLUSH LOGS': flush, respectively.

   * It is not allowed to partition log tables.


File: manual.info,  Node: error-log,  Next: query-log,  Prev: log-tables,  Up: server-logs

5.2.2 The Error Log
-------------------

The error log contains information indicating when *Note `mysqld':
mysqld. was started and stopped and also any critical errors that occur
while the server is running. If *Note `mysqld': mysqld. notices a table
that needs to be automatically checked or repaired, it writes a message
to the error log.

On some operating systems, the error log contains a stack trace if
*Note `mysqld': mysqld. dies. The trace can be used to determine where
*Note `mysqld': mysqld. died. See MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).

You can specify where *Note `mysqld': mysqld. writes the error log with
the `--log-error[=FILE_NAME]' option. If no FILE_NAME value is given,
*Note `mysqld': mysqld. uses the name `HOST_NAME.err' by default and
writes the file in the data directory. If you execute *Note `FLUSH
LOGS': flush, the error log is renamed with the suffix `-old' and *Note
`mysqld': mysqld. creates a new empty log file. (No renaming occurs if
the `--log-error' option was not given to *Note `mysqld': mysqld.)

If you do not specify `--log-error', or (on Windows) if you use the
`--console' option, errors are written to `stderr', the standard error
output.  Usually this is your terminal.

On Windows, error output is always written to the `.err' file if
`--console' is not given.

The `--log-warnings' option or `log_warnings' system variable can be
used to control warning logging to the error log. The default value is
enabled (1). Warning logging can be disabled using a value of 0. If the
value is greater than 1, aborted connections are written to the error
log. See *Note communication-errors::.

If you use *Note `mysqld_safe': mysqld-safe. to start *Note `mysqld':
mysqld, *Note `mysqld_safe': mysqld-safe. arranges for *Note `mysqld':
mysqld. to write error messages to a log file or to `syslog' *Note
`mysqld_safe': mysqld-safe. has three error-logging options, `--syslog',
`--skip-syslog', and `--log-error'. The default with no logging options
or with `--skip-syslog' is to use the default log file. To explicitly
specify use of an error log file, specify `--log-error=FILE_NAME' to
*Note `mysqld_safe': mysqld-safe, and *Note `mysqld_safe': mysqld-safe.
will arrange for *Note `mysqld': mysqld. to write messages to a log
file. To use `syslog' instead, specify the `--syslog' option.

If you specify `--log-error' in an option file in a section that *Note
`mysqld': mysqld. reads, *Note `mysqld_safe': mysqld-safe. also will
find and use the option.

For logging to `syslog', messages from *Note `mysqld_safe':
mysqld-safe. and *Note `mysqld': mysqld. are written with a tag of
`mysqld_safe' and `mysqld', respectively. To specify a suffix for the
tag, use `--syslog-tag=TAG', which modifies the tags to be
`mysqld_safe-TAG' and `mysqld-TAG'.

If *Note `mysqld_safe': mysqld-safe. is used to start *Note `mysqld':
mysqld. and *Note `mysqld': mysqld. dies unexpectedly, *Note
`mysqld_safe': mysqld-safe. notices that it needs to restart *Note
`mysqld': mysqld. and writes a `restarted mysqld' message to the error
log.


File: manual.info,  Node: query-log,  Next: binary-log,  Prev: error-log,  Up: server-logs

5.2.3 The General Query Log
---------------------------

The general query log is a general record of what *Note `mysqld':
mysqld. is doing. The server writes information to this log when
clients connect or disconnect, and it logs each SQL statement received
from clients. The general query log can be very useful when you suspect
an error in a client and want to know exactly what the client sent to
*Note `mysqld': mysqld.

*Note `mysqld': mysqld. writes statements to the query log in the order
that it receives them, which might differ from the order in which they
are executed. This logging order contrasts to the binary log, for which
statements are written after they are executed but before any locks are
released. (Also, the query log contains all statements, whereas the
binary log does not contain statements that only select data.)

To enable the general query log, start *Note `mysqld': mysqld.  with the
`--log[=FILE_NAME]' or `-l [FILE_NAME]' option, and optionally use
`--log-output' to specify the log destination (as described in *Note
log-tables::). As of MySQL 6.0.8, `--log' and `-l' are deprecated: Use
`--general_log' to enable the general query log, and optionally
`--general_log_file=FILE_NAME' to specify a log file name.
`--general_log' takes an optional argument of 1 or 0 to enable or
disable the log.

If you specify no file name for the general query log, the default name
is `HOST_NAME.log' in the data directory. If you specify a file name
that is not an absolute path name, the server writes the file in the
data directory.

When `--log' or `-l' is specified, `--general_log' also may be given to
specify the initial general query log state. With no argument or an
argument of 0, the option disables the log. If omitted or given with an
argument of 1, the option enables the log.

For runtime control of the general query log, use the global
`general_log' and `general_log_file' system variables. Set
`general_log' to 0 (or `OFF') to disable the log or to 1 (or `ON') to
enable it. Set `general_log_file' to specify the name of the log file.
If a log file already is open, it is closed and the new file is opened.

When the general query log is enabled, output is written to any
destinations specified by the `--log-output' option or `log_output'
system variable. If you enable the log, the server opens the log file
and writes startup messages to it. However, logging of queries to the
file does not occur unless the `FILE' log destination is selected. If
the destination is `NONE', no queries are written even if the general
log is enabled. Setting the log file name has no effect on logging if
the log destination value does not contain `FILE'.

Server restarts and log flushing do not cause a new general query log
file to be generated (although flushing closes and reopens it). On
Unix, you can rename the file and create a new one by using the
following commands:

     shell> mv HOST_NAME.log HOST_NAME-old.log
     shell> mysqladmin flush-logs
     shell> cp HOST_NAME-old.log BACKUP-DIRECTORY
     shell> rm HOST_NAME-old.log

On Windows, you can rename the general query log or slow query log
while the server has it open. You cannot rename the error log file
while the server has it open. You must stop the server and rename the
file, and then restart the server to create a new log file.  However, a
stop and restart can be avoided by using *Note `FLUSH LOGS': flush,
which causes the server to rename the error log with an `-old' suffix
and open a new error log.

You can disable the general query log at runtime:

     SET GLOBAL general_log = 'OFF';

With the log disabled, rename the log file externally; for example,
from the command line. Then enable the log again:

     SET GLOBAL general_log = 'ON';

This method works on any platform and does not require a server restart.

The session `sql_log_off' variable can be set to `ON' or `OFF' to
disable or enable general query logging for the current connection.

The general query log should be protected because logged statements
might contain passwords. See *Note password-security-admin::.


File: manual.info,  Node: binary-log,  Next: slow-query-log,  Prev: query-log,  Up: server-logs

5.2.4 The Binary Log
--------------------

* Menu:

* binary-log-formats::           Binary Logging Formats
* binary-log-setting::           Setting The Binary Log Format
* binary-log-mixed::             Mixed Binary Logging Format
* binary-log-mysql-database::    Logging Format for Changes to `mysql' Database Tables

The binary log contains all statements that update data. It also
contains statements that potentially could have updated it (for
example, a *Note `DELETE': delete. which matched no rows), unless
row-based logging is used. Statements are stored in the form of
`events' that describe the modifications.  The binary log also contains
information about how long each statement took that updated data. The
binary log has two important purposes:

   * For replication, the binary log is used on master replication
     servers as a record of the statements to be sent to slave servers.
     The master server sends the events contained in its binary log to
     its slaves, which execute those events to make the same data
     changes that were made on the master. See *Note
     replication-implementation::.

   * Certain data recovery operations require use of the binary log.
     After a backup file has been restored, the events in the binary
     log that were recorded after the backup was made are re-executed.
     These events bring databases up to date from the point of the
     backup. See *Note recovery-from-backups::.

The binary log is not used for statements such as *Note `SELECT':
select. or *Note `SHOW': show. that do not modify data. If you want to
log all statements (for example, to identify a problem query), use the
general query log. See *Note query-log::.

The binary log should be protected because logged statements might
contain passwords. See *Note password-security-admin::.

The format of the events recorded in the binary log is dependent on the
binary logging format. Three format types are supported, row-based
logging, statement-based logging and mixed-base logging.  The binary
logging format used depends on the MySQL version. For more information
on logging formats, see *Note binary-log-formats::.

MySQL Enterprise

The binary log can also be used to track significant DDL events.
Analyzing the binary log in this way is an integral part of the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

Running the server with the binary log enabled makes performance about
1% slower. However, the benefits of the binary log for restore
operations and in allowing you to set up replication generally outweigh
this minor performance decrement.

When started with the `--log-bin[=BASE_NAME]' option, *Note `mysqld':
mysqld. writes a log file containing all SQL statements that update
data (both DDL and DML statements). If no BASE_NAME value is given, the
default name is the value of the `pid-file' option (which by default is
the name of host machine) followed by `-bin'. If the basename is given,
but not as an absolute path name, the server writes the file in the data
directory. It is recommended that you specify a basename; see
Additional Known Issues
(http://dev.mysql.com/doc/refman/5.1/en/bugs.html#open-bugs-general),
for the reason.

*Note*:

From MySQL 6.0.0 through 6.0.3, `mysql' was used when no BASE_NAME was
specified. Also in these versions, a path given as part of the
`--log-bin' options was treated as absolute rather than relative. The
previous behaviors were restored in MySQL 6.0.4. (See Bug#28603
(http://bugs.mysql.com/28603) and Bug#28597
(http://bugs.mysql.com/28597).)

If you supply an extension in the log name (for example,
`--log-bin=BASE_NAME.EXTENSION'), the extension is silently removed and
ignored.

*Note `mysqld': mysqld. appends a numeric extension to the binary log
basename to generate binary log file names. The number increases each
time the server creates a new log file, thus creating an ordered series
of files. The server creates a new file in the series each time it
starts or flushes the logs. The server also creates a new binary log
file automatically when the current log's size reaches
`max_binlog_size'. A binary log file may become larger than
`max_binlog_size' if you are using large transactions because a
transaction is written to the file in one piece, never split between
files.

To keep track of which binary log files have been used, *Note `mysqld':
mysqld. also creates a binary log index file that contains the names of
all used binary log files. By default, this has the same basename as
the binary log file, with the extension `'.index''. You can change the
name of the binary log index file with the `--log-bin-index[=FILE_NAME]'
option. You should not manually edit this file while *Note `mysqld':
mysqld. is running; doing so would confuse *Note `mysqld': mysqld.

You can delete all binary log files with the *Note `RESET MASTER':
reset-master. statement, or a subset of them with *Note `PURGE BINARY
LOGS': purge-binary-logs. See *Note reset::, and *Note
purge-binary-logs::.

Writes to the binary log file and binary log index file are handled in
the same way as writes to `MyISAM' tables. See *Note full-disk::.

The binary log format has some known limitations that can affect
recovery from backups. See *Note replication-features::.

Binary logging for stored routines and triggers is done as described in
*Note stored-programs-logging::.

A replication slave server by default does not write to its own binary
log any data modifications that are received from the replication
master. To log these modifications, start the slave with the
`--log-slave-updates' option (see also *Note
replication-options-slave::).

Evaluation of update selection options

The server evaluates the options for logging or ignoring updates to the
binary log according to the following rules:

  1. Are there `--binlog-do-db' or `--binlog-ignore-db' rules?

        * No: Write the statement to the binary log and exit.

        * Yes: Go to the next step.

  2. There are some rules (`--binlog-do-db', `--binlog-ignore-db', or
     both).  Is there a default database (has any database been
     selected by *Note `USE': use.?)?

        * No: Do _not_ write the statement, and exit.

        * Yes: Go to the next step.

  3. There is a default database. Are there some `--binlog-do-db' rules?

        * Yes: Does the default database match any of the
          `--binlog-do-db' rules?

             * Yes: Write the statement and exit.

             * No: Do _not_ write the statement, and exit.

        * No: Go to the next step.

  4. There are some `--binlog-ignore-db' rules. Does the default
     database match any of the `--binlog-ignore-db' rules?

        * Yes: Do not write the statement, and exit.

        * No: Write the query and exit.

*Important*:

An exception is made in the rules just given for the *Note `CREATE
DATABASE': create-database, *Note `ALTER DATABASE': alter-database, and
*Note `DROP DATABASE': drop-database. statements (see *Note
replication-options-binary-log::). In those cases, the database being
_created, altered, or dropped_ replaces the default database when
determining whether to log or ignore updates.

For example, a slave running with only `--binlog-do-db=sales' does not
write to the binary log any statement for which the default database is
different from `sales' (in other words, `--binlog-do-db' can sometimes
mean `ignore other databases').

If you are using replication, you should not delete old binary log
files until you are sure that no slave still needs to use them.  For
example, if your slaves never run more than three days behind, once a
day you can execute *Note `mysqladmin flush-logs': mysqladmin. on the
master and then remove any logs that are more than three days old. You
can remove the files manually, but it is preferable to use *Note `PURGE
BINARY LOGS': purge-binary-logs, which also safely updates the binary
log index file for you (and which can take a date argument). See *Note
purge-binary-logs::.

A client that has the `SUPER' privilege can disable binary logging of
its own statements by using a `SET sql_log_bin=0' statement. See *Note
server-session-variables::.

You can display the contents of binary log files with the *Note
`mysqlbinlog': mysqlbinlog. utility. This can be useful when you want
to reprocess statements in the log. For example, you can update a MySQL
server from the binary log as follows:

     shell> mysqlbinlog LOG_FILE | mysql -h SERVER_NAME

See *Note mysqlbinlog::, for more information on the *Note
`mysqlbinlog': mysqlbinlog. utility and how to use it.  *Note
`mysqlbinlog': mysqlbinlog. also can be used with relay log files
because they are written using the same format as binary log files.

Binary logging is done immediately after a statement completes but
before any locks are released or any commit is done. This ensures that
the log is logged in execution order.

Updates to non-transactional tables are stored in the binary log
immediately after execution. In MySQL 6.0.3 and earlier versions of
MySQL 6.0, an *Note `UPDATE': update. statement using a stored function
that modified a non-transactional table was not logged if it failed,
and an `INSERT ... ON DUPLICATE KEY UPDATE' statement that encountered
a duplicate key constraint -- but which did not actually change any data
-- was not logged. Beginning with MySQL 6.0.4, both of these statements
are written to the binary log. (Bug#23333 (http://bugs.mysql.com/23333))

Within an uncommitted transaction, all updates (*Note `UPDATE': update,
*Note `DELETE': delete, or *Note `INSERT': insert.) that change
transactional tables such as `BDB' or `InnoDB' tables are cached until
a *Note `COMMIT': commit.  statement is received by the server. At that
point, *Note `mysqld': mysqld. writes the entire transaction to the
binary log before the *Note `COMMIT': commit. is executed. When the
thread that handles the transaction starts, it allocates a buffer of
`binlog_cache_size' to buffer statements. If a statement is bigger than
this, the thread opens a temporary file to store the transaction. The
temporary file is deleted when the thread ends.

Modifications to non-transactional tables cannot be rolled back.  If a
transaction that is rolled back includes modifications to
non-transactional tables, the entire transaction is logged with a *Note
`ROLLBACK': commit.  statement at the end to ensure that the
modifications to those tables are replicated.

The `Binlog_cache_use' status variable shows the number of transactions
that used this buffer (and possibly a temporary file) for storing
statements. The `Binlog_cache_disk_use' status variable shows how many
of those transactions actually had to use a temporary file. These two
variables can be used for tuning `binlog_cache_size' to a large enough
value that avoids the use of temporary files.

The `max_binlog_cache_size' system variable (default 4GB, which is also
the maximum) can be used to restrict the total size used to cache a
multiple-statement transaction. If a transaction is larger than this
many bytes, it fails and rolls back. The minimum value is 4096.

If you are using the binary log and row based logging, concurrent
inserts are converted to normal inserts for `CREATE ...  SELECT' or
*Note `INSERT ... SELECT': insert-select. statement. This is done to
ensure that you can re-create an exact copy of your tables by applying
the log during a backup operation. If you are using statement based
logging then the original statement is written to the log.

Note that the binary log format is different in MySQL 6.0 from previous
versions of MySQL, due to enhancements in replication. See *Note
replication-compatibility::.

By default, the binary log is not synchronized to disk at each write.
So if the operating system or machine (not only the MySQL server)
crashes, there is a chance that the last statements of the binary log
are lost. To prevent this, you can make the binary log be synchronized
to disk after every N writes to the binary log, with the `sync_binlog'
system variable. See *Note server-system-variables::. 1 is the safest
value for `sync_binlog', but also the slowest. Even with `sync_binlog'
set to 1, there is still the chance of an inconsistency between the
table content and binary log content in case of a crash. For example,
if you are using `InnoDB' tables and the MySQL server processes a *Note
`COMMIT': commit.  statement, it writes the whole transaction to the
binary log and then commits this transaction into `InnoDB'. If the
server crashes between those two operations, the transaction is rolled
back by `InnoDB' at restart but still exists in the binary log. To
resolve this, you should set `--innodb_support_xa' to 1. Although this
option is related to the support of XA transactions in InnoDB, it also
ensures that the binary log and InnoDB data files are synchronized.

For this option to provide a greater degree of safety, the MySQL server
should also be configured to synchronize the binary log and the
`InnoDB' logs to disk at every transaction.  The `InnoDB' logs are
synchronized by default, and `sync_binlog=1' can be used to synchronize
the binary log. The effect of this option is that at restart after a
crash, after doing a rollback of transactions, the MySQL server cuts
rolled back `InnoDB' transactions from the binary log. This ensures
that the binary log reflects the exact data of `InnoDB' tables, and so,
that the slave remains in synchrony with the master (not receiving a
statement which has been rolled back).

If the MySQL server discovers at crash recovery that the binary log is
shorter than it should have been, it lacks at least one successfully
committed `InnoDB' transaction. This should not happen if
`sync_binlog=1' and the disk/file system do an actual sync when they
are requested to (some don't), so the server prints an error message
`The binary log <name> is shorter than its expected size'. In this
case, this binary log is not correct and replication should be
restarted from a fresh snapshot of the master's data.

The session values of the following system variables are written to the
binary log and honored by the replication slave when parsing the binary
log:

   * `sql_mode'

   * `foreign_key_checks'

   * `unique_checks'

   * `character_set_client'

   * `collation_connection'

   * `collation_database'

   * `collation_server'

   * `sql_auto_is_null'


File: manual.info,  Node: binary-log-formats,  Next: binary-log-setting,  Prev: binary-log,  Up: binary-log

5.2.4.1 Binary Logging Formats
..............................

A number of different logging formats are used to record information in
the binary log. The exact format employed depends on the version of
MySQL being used. There are three logging formats:

   * Replication capabilities in MySQL originally were based on
     propagation of SQL statements from master to slave. This is called
     _statement-based logging_. You can cause this format to be used by
     starting the server with `--binlog-format=STATEMENT'.

   * In _row-based logging_, the master writes events to the binary log
     that indicate how individual table rows are affected. You can
     cause the server to use row-based logging by starting it with
     `--binlog-format=ROW'.

   * A third option is also available: _mixed logging_. With mixed
     logging, statement-based logging is used by default, but the
     logging mode switches automatically to row-based in certain cases
     as described below. You can cause MySQL to use mixed logging
     explicitly by starting *Note `mysqld': mysqld. with the option
     `--binlog-format=MIXED'.

     Mixed logging is the default logging mode in MySQL 6.0.

     The logging format can also be set or limited by the storage
     engine being used. This helps to eliminate issues when logging,
     and more specifically replicating, certain statements between a
     master and slave which are using different storage engines.


File: manual.info,  Node: binary-log-setting,  Next: binary-log-mixed,  Prev: binary-log-formats,  Up: binary-log

5.2.4.2 Setting The Binary Log Format
.....................................

The default binary logging format is mixed-based in MySQL 6.0.

You can force the replication format by starting the MySQL server with
`--binlog-format=TYPE'.  When set, all replication slaves connecting to
the server will read the events according to this setting. The
supported values for TYPE are:

   * `ROW' causes replication to be row-based.

   * `STATEMENT' causes replication to be statement-based.

   * `MIXED' causes replication to use mixed format.

The logging format also can be switched at runtime. To specify the
format globally for all clients, set the global value of the
`binlog_format' system variable.  (To change the global value, you must
have need the `SUPER' privilege. This is also true for the `SESSION'
value as of MySQL 6.0.8.)

To switch to statement-based format, use either of these statements:

     mysql> SET GLOBAL binlog_format = 'STATEMENT';
     mysql> SET GLOBAL binlog_format = 1;

To switch to row-based format, use either of these statements:

     mysql> SET GLOBAL binlog_format = 'ROW';
     mysql> SET GLOBAL binlog_format = 2;

To switch to mixed format, use either of these statements:

     mysql> SET GLOBAL binlog_format = 'MIXED';
     mysql> SET GLOBAL binlog_format = 3;

An individual client can control the logging format for its own
statements by setting the session value of `binlog_format'. For example:

     mysql> SET SESSION binlog_format = 'STATEMENT';
     mysql> SET SESSION binlog_format = 'ROW';
     mysql> SET SESSION binlog_format = 'MIXED';

In addition to switching the logging format manually, a slave server
may switch the format _automatically_.  This happens when the server is
running in either `STATEMENT' or `MIXED' format and encounters a row in
the binary log that is written in `ROW' logging format. In that case,
the slave switches to row-based replication temporarily for that event,
and switches back to the previous format afterwards.

There are two reasons why you might want to set replication logging on
a per-connection basis:

   * A thread that makes many small changes to the database might want
     to use row-based logging. A thread that performs updates that
     match many rows in the `WHERE' clause might want to use
     statement-based logging because it will be more efficient to log a
     few statements than many rows.

   * Some statements require a lot of execution time on the master, but
     result in just a few rows being modified. It might therefore be
     beneficial to replicate them using row-based logging.

There are exceptions when you cannot switch the replication format at
runtime:

   * From within a stored function or a trigger.

   * If the `NDBCLUSTER' storage engine is enabled.

   * If the session is currently in row-based replication mode and has
     open temporary tables.

Trying to switch the format in any of these cases results in an error.

Switching the replication format at runtime is not recommended when any
temporary tables exist, because temporary tables are logged only when
using statement-based replication, whereas with row-based replication
they are not logged. With mixed replication, temporary tables are
usually logged; exceptions happen with user-defined functions (UDFs)
and with the `UUID()' function.

With the binlog format set to `ROW', many changes are written to the
binary log using the row-based format. Some changes, however, still use
the statement-based format. Examples include all DDL (data definition
language) statements such as *Note `CREATE TABLE': create-table, *Note
`ALTER TABLE': alter-table, or *Note `DROP TABLE': drop-table.

The `--binlog-row-event-max-size' option is available for servers that
are capable of row-based replication. Rows are stored into the binary
log in chunks having a size in bytes not exceeding the value of this
option.  The value must be a multiple of 256. The default value is 1024.

*Warning*:

When using _statement-based logging_ in a replication scenario, it is
possible for the data on the master and slave to become different if a
statement is designed in such a way that the data modification is
_non-deterministic_; that is, it is left to the will of the query
optimizer. In general, this is not a good practice even outside of
replication. For a detailed explanation of this issue, see Additional
Known Issues
(http://dev.mysql.com/doc/refman/5.1/en/bugs.html#open-bugs-general).


File: manual.info,  Node: binary-log-mixed,  Next: binary-log-mysql-database,  Prev: binary-log-setting,  Up: binary-log

5.2.4.3 Mixed Binary Logging Format
...................................

When running in `MIXED' mode, automatic switching from statement-based
to row-based replication takes place under the following conditions:

   * When a function contains `UUID()'

   * When 2 or more tables with `AUTO_INCREMENT' columns are updated

   * When any *Note `INSERT DELAYED': insert-delayed. is executed

   * When the body of a view requires row-based replication, the
     statement creating the view also uses it -- for example, this
     occurs when the statement creating a view uses the `UUID()'
     function

   * When a call to a UDF is involved

   * If a statement is logged by row and the client that executed the
     statement has any temporary tables, then logging by row is used
     for all subsequent statements (except for those accessing
     temporary tables) until all temporary tables in use by that client
     are dropped

     This is true whether or not any temporary tables are actually
     logged

     Temporary tables cannot be logged using the row-based format;
     thus, once row-based logging is used, all subsequent statements
     using that table are unsafe, and we approximate this condition by
     treating all statements made by that client as unsafe until the
     client no longer holds any temporary tables

   * Beginning with MySQL 6.0.4:

        * When `FOUND_ROWS()' or `ROW_COUNT()' is used (Bug#12092
          (http://bugs.mysql.com/12092), Bug#30244
          (http://bugs.mysql.com/30244))

        * When `USER()', `CURRENT_USER()', or `CURRENT_USER' is used
          (Bug#28086 (http://bugs.mysql.com/28086))

        * Beginning with MySQL 6.0.5, when a statement refers to one or
          more system variables. (Bug#31168
          (http://bugs.mysql.com/31168))

*Note*:

A warning is generated if you try to log execute a statement in
statement-logging mode that should be logged in row-logging mode. The
warning is shown both in the client (in the output of *Note `SHOW
WARNINGS': show-warnings.) and through the *Note `mysqld': mysqld.
error log. A warning is added to the *Note `SHOW WARNINGS':
show-warnings. table each time a statement is executed. However, only
the first statement that generated the warning for each client session
is logged to the `mysqld' error log to prevent flooding the error log.

In addition to the decisions above, individual engines can also
determine the logging format used when information in a table is
updated. The following table lists the logging formats supported by
each storage engine.

Storage Engine                       Row Logging        Statement Logging
                                     Supported          Supported
`ARCHIVE'                            Yes                Yes
`BLACKHOLE'                          No                 Yes
`CSV'                                Yes                Yes
`EXAMPLE'                            Yes                No
`Falcon'                             Yes                No
`FEDERATED'                          Yes                Yes
`HEAP'                               Yes                Yes
`InnoDB'                             Yes                Yes
`MyISAM'                             Yes                Yes
`MERGE'                              Yes                Yes

A given storage engine can support either or both logging formats; the
logging capabilities of an individual engine can be further defined as
follows:

   * If an engine supports row-based logging, then the engine is said
     to be _row-logging capable_.

   * If an engine supports statement-based logging, then the engine is
     said to be _statement-logging capable_.

When determining the logging mode to be used, the capabilities of all
the tables affected by the event are combined. The set of affected
tables is then marked according to these rules:

   * A set of tables is defined as _row logging restricted_ if the
     tables are row logging capable but not statement logging capable.

   * A set of tables is defined as _statement logging restricted_ if
     the tables are statement logging capable but not row logging
     capable.

Once the determination of the possible logging formats required by the
statement is complete it is compared to the current `binlog_format'
setting. The following table is used to decide how the information is
recorded in the binary log or, if appropriate, whether an error is
raised. In the table, a safe operation is defined as one that is
deterministic. A number of rules decide whether the statement is
deterministic or not, as shown in the following table (where *RLC*
stands for `row-logging capable' and *SLC* stands for
`statement-logging capable').

ConditionAction                                            
Safe/unsafe`binlog_format'    RLC     SLC     Error/Warning  Logged as
Safe    STATEMENT          N       N       Error: not     
                                           loggable       
Safe    STATEMENT          N       Y                      STATEMENT
Safe    STATEMENT          Y       N       Error: not     
                                           loggable       
Safe    STATEMENT          Y       Y                      STATEMENT
Safe    MIXED              N       N       Error: not     
                                           loggable       
Safe    MIXED              N       Y                      STATEMENT
Safe    MIXED              Y       N                      ROW
Safe    MIXED              Y       Y                      STATEMENT
Safe    ROW                N       N       Error: not     
                                           loggable       
Safe    ROW                N       Y       Error: not     
                                           loggable       
Safe    ROW                Y       N                      ROW
Safe    ROW                Y       Y                      ROW
Unsafe  STATEMENT          N       N       Error: not     
                                           loggable       
Unsafe  STATEMENT          N       Y       Warning:       STATEMENT
                                           unsafe         
Unsafe  STATEMENT          Y       N       Error: not     
                                           loggable       
Unsafe  STATEMENT          Y       Y       Warning:       STATEMENT
                                           unsafe         
Unsafe  MIXED              N       N       Error: not     
                                           loggable       
Unsafe  MIXED              N       Y       Error: not     
                                           loggable       
Unsafe  MIXED              Y       N                      ROW
Unsafe  MIXED              Y       Y                      ROW
Unsafe  ROW                N       N       Error: not     
                                           loggable       
Unsafe  ROW                N       Y       Error: not     
                                           loggable       
Unsafe  ROW                Y       N                      ROW
Unsafe  ROW                Y       Y                      ROW

When a warning is produced by the determination, a standard MySQL
warning is produced (and is available using *Note `SHOW WARNINGS':
show-warnings.). The information is also written to the *Note `mysqld':
mysqld. error log. Only one error for each error instance per client
connection is logged. The log message will include the SQL statement
that was attempted.

If a slave server was started with `--log-warnings' enabled, the slave
prints messages to the error log to provide information about its
status, such as the binary log and relay log coordinates where it
starts its job, when it is switching to another relay log, when it
reconnects after a disconnect, and so forth.


File: manual.info,  Node: binary-log-mysql-database,  Prev: binary-log-mixed,  Up: binary-log

5.2.4.4 Logging Format for Changes to `mysql' Database Tables
.............................................................

The contents of the grant tables in the `mysql' database can be
modified directly (for example, with *Note `INSERT': insert. or *Note
`DELETE': delete.) or indirectly (for example, with *Note `GRANT':
grant. or *Note `CREATE USER': create-user.). Statements that affect
`mysql' database tables are written to the binary log using the
following rules:

   * Data manipulation statements that change data in `mysql' database
     tables directly are logged according to the setting of the
     `binlog_format' system variable. This pertains to statements such
     as *Note `INSERT': insert, *Note `UPDATE': update, *Note `DELETE':
     delete, *Note `REPLACE': replace, *Note `DO': do, *Note `LOAD DATA
     INFILE': load-data, *Note `SELECT': select, and *Note `TRUNCATE':
     truncate.

   * Statements that change the `mysql' database indirectly are logged
     as statements regardless of the value of `binlog_format'. This
     pertains to statements such as *Note `GRANT': grant, *Note
     `REVOKE': revoke, *Note `SET PASSWORD': set-password, *Note
     `RENAME USER': rename-user, `CREATE' (all forms except `CREATE
     TABLE ... SELECT'), `ALTER' (all forms), and `DROP' (all forms).

`CREATE TABLE ... SELECT' is a combination of data definition and data
manipulation. The *Note `CREATE TABLE': create-table. part is logged
using statement format and the *Note `SELECT': select.  part is logged
according to the value of `binlog_format'.


File: manual.info,  Node: slow-query-log,  Next: log-file-maintenance,  Prev: binary-log,  Up: server-logs

5.2.5 The Slow Query Log
------------------------

The slow query log consists of all SQL statements that took more than
`long_query_time' seconds to execute and (as of MySQL 6.0.4) required
at least `min_examined_row_limit' rows to be examined. The time to
acquire the initial table locks is not counted as execution time. *Note
`mysqld': mysqld. writes a statement to the slow query log after it has
been executed and after all locks have been released, so log order
might be different from execution order. The default value of
`long_query_time' is 10. Prior to MySQL 6.0.4, the minimum value is 1,
and the value for this variable must be an integer. Beginning with
MySQL 6.0.4, the minimum is 0, and a resolution of microseconds is
supported when logging to a file. However, the microseconds part is
ignored and only integer values are written when logging to tables.

To enable the slow query log, start *Note `mysqld': mysqld. with the
`--log-slow-queries[=FILE_NAME]' option, and optionally use
`--log-output' to specify the log destination (as described in *Note
log-tables::). As of MySQL 6.0.8, `--log-slow-queries' is deprecated:
Use `--slow_query_log' to enable the slow query log, and optionally
`--slow_query_log_file=FILE_NAME' to specify a log file name.
`--slow_query_log' takes an optional argument of 1 or 0 to enable or
disable the log.

If you specify no file name for the slow query log, the default name is
`HOST_NAME-slow.log' in the data directory. If you specify a file name
that is not an absolute path name, the server writes the file in the
data directory.

When `--log-slow-queries' is specified, `--slow_query_log' also may be
given to specify the initial slow query log state. With no argument or
an argument of 0, the option disables the log. If omitted or given with
an argument of 1, the option enables the log.

For runtime control of the general query log, use the global
`slow_query_log' and `slow_query_log_file' system variables. Set
`slow_query_log' to 0 (or `OFF') to disable the log or to 1 (or `ON')
to enable it. Set `general_log_file' to specify the name of the log
file. If a log file already is open, it is closed and the new file is
opened.

When the slow query log is enabled, output is written to any
destinations specified by the `--log-output' option or `log_output'
system variable. If you enable the log, the server opens the log file
and writes startup messages to it. However, logging of queries to the
file does not occur unless the `FILE' log destination is selected. If
the destination is `NONE', no queries are written even if the slow
query log is enabled. Setting the log file name has no effect on
logging if the log destination value does not contain `FILE'.

When the slow query log is enabled, output is written to any
destinations specified by the `--log-output' option or `log_output'
system variable. If the destination is `NONE', no output is written
even if the slow query log is enabled. Setting the log file name has no
effect on logging if the log destination value does not contain `FILE'.

The slow query log can be used to find queries that take a long time to
execute and are therefore candidates for optimization.  However,
examining a long slow query log can become a difficult task. To make
this easier, you can process the slow query log using the *Note
`mysqldumpslow': mysqldumpslow. command to summarize the queries that
appear in the log. Use *Note `mysqldumpslow --help': mysqldumpslow. to
see the options that this command supports.

In MySQL 6.0, queries that do not use indexes are logged in the slow
query log if the `--log-queries-not-using-indexes' option is specified.
See *Note server-options::.

MySQL Enterprise

Excessive table scans are indicative of missing or poorly optimized
indexes. Using an advisor specifically designed for the task, the MySQL
Enterprise Monitor can identify such problems and offer advice on
resolution. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

In MySQL 6.0, the `--log-slow-admin-statements' server option enables
you to request logging of slow administrative statements such as *Note
`OPTIMIZE TABLE': optimize-table, *Note `ANALYZE TABLE': analyze-table,
and *Note `ALTER TABLE': alter-table. to the slow query log.

Queries handled by the query cache are not added to the slow query log,
nor are queries that would not benefit from the presence of an index
because the table has zero rows or one row.

Prior to MySQL 6.0.11, replication slaves did not write replicated
queries to the slow query log, even if the same queries were written to
the slow query log on the master. (Bug#23300
(http://bugs.mysql.com/23300))

The slow query log should be protected because logged statements might
contain passwords. See *Note password-security-admin::.


File: manual.info,  Node: log-file-maintenance,  Prev: slow-query-log,  Up: server-logs

5.2.6 Server Log Maintenance
----------------------------

MySQL Server can create a number of different log files that make it
easy to see what is going on. See *Note server-logs::. However, you
must clean up these files regularly to ensure that the logs do not take
up too much disk space.

When using MySQL with logging enabled, you may want to back up and
remove old log files from time to time and tell MySQL to start logging
to new files. See *Note backup::.

On a Linux (Red Hat) installation, you can use the `mysql-log-rotate'
script for this. If you installed MySQL from an RPM distribution, this
script should have been installed automatically. You should be careful
with this script if you are using the binary log for replication. You
should not remove binary logs until you are certain that their contents
have been processed by all slaves.

On other systems, you must install a short script yourself that you
start from `cron' (or its equivalent) for handling log files.

For the binary log, you can set the `expire_logs_days' system variable
to expire binary log files automatically after a given number of days
(see *Note server-system-variables::). If you are using replication,
you should set the variable no lower than the maximum number of days
your slaves might lag behind the master.

You can force MySQL to start using new log files by issuing a *Note
`FLUSH LOGS': flush.  statement or executing *Note `mysqladmin
flush-logs': mysqladmin. or *Note `mysqladmin refresh': mysqladmin. See
*Note flush::, and *Note mysqladmin::.

A log flushing operation does the following:

   * If general query logging or slow query logging to a log file is
     enabled, the server closes and reopens the general query log file
     or slow query log file.

   * If binary logging is enabled, the server closes the current binary
     log file and opens a new log file with the next sequence number.

   * If the server was given an error log file name with the
     `--log-error' option, it renames the error log with the suffix
     `-old' and creates a new empty error log file.

The server creates a new binary log file when you flush the logs.
However, it just closes and reopens the general and slow query log
files. To cause new files to be created on Unix, rename the current
logs before flushing them. At flush time, the server will open new logs
with the original names. For example, if the general and slow query
logs are named `mysql.log' and `mysql-slow.log', you can use a series of
commands like this:

     shell> cd MYSQL-DATA-DIRECTORY
     shell> mv mysql.log mysql.old
     shell> mv mysql-slow.log mysql-slow.old
     shell> mysqladmin flush-logs

At this point, you can make a backup of `mysql.old' and
`mysql-slow.log' and then remove them from disk.

On Windows, you can rename the general query log or slow query log
while the server has it open. You cannot rename the error log file
while the server has it open. You must stop the server and rename the
file, and then restart the server to create a new log file.  However, a
stop and restart can be avoided by using *Note `FLUSH LOGS': flush,
which causes the server to rename the error log with an `-old' suffix
and open a new error log.

You can disable the general query log or slow query log at runtime:

     SET GLOBAL general_log = 'OFF';
     SET GLOBAL slow_query_log = 'OFF';

With the logs disabled, rename the log files externally; for example,
from the command line. Then enable the logs again:

     SET GLOBAL general_log = 'ON';
     SET GLOBAL slow_query_log = 'ON';

This method works on any platform and does not require a server restart.


File: manual.info,  Node: security,  Next: privilege-system,  Prev: server-logs,  Up: server-administration

5.3 General Security Issues
===========================

* Menu:

* security-guidelines::          General Security Guidelines
* security-against-attack::      Making MySQL Secure Against Attackers
* privileges-options::           Security-Related `mysqld' Options
* load-data-local::              Security Issues with `LOAD DATA LOCAL'
* changing-mysql-user::          How to Run MySQL as a Normal User

This section describes some general security issues to be aware of and
what you can do to make your MySQL installation more secure against
attack or misuse. For information specifically about the access control
system that MySQL uses for setting up user accounts and checking
database access, see *Note privilege-system::.

For answers to some questions that are often asked about MySQL Server
security issues, see *Note faqs-security::.


File: manual.info,  Node: security-guidelines,  Next: security-against-attack,  Prev: security,  Up: security

5.3.1 General Security Guidelines
---------------------------------

Anyone using MySQL on a computer connected to the Internet should read
this section to avoid the most common security mistakes.

In discussing security, we emphasize the necessity of fully protecting
the entire server host (not just the MySQL server) against all types of
applicable attacks: eavesdropping, altering, playback, and denial of
service. We do not cover all aspects of availability and fault
tolerance here.

MySQL uses security based on Access Control Lists (ACLs) for all
connections, queries, and other operations that users can attempt to
perform. There is also support for SSL-encrypted connections between
MySQL clients and servers. Many of the concepts discussed here are not
specific to MySQL at all; the same general ideas apply to almost all
applications.

When running MySQL, follow these guidelines whenever possible:

   * *Do not ever give anyone (except MySQL `root' accounts) access to
     the `user' table in the `mysql' database!* This is critical.

   * Learn the MySQL access privilege system. The *Note `GRANT': grant.
     and *Note `REVOKE': revoke. statements are used for controlling
     access to MySQL. Do not grant more privileges than necessary.
     Never grant privileges to all hosts.

     Checklist:

        * Try `mysql -u root'. If you are able to connect successfully
          to the server without being asked for a password, anyone can
          connect to your MySQL server as the MySQL `root' user with
          full privileges!  Review the MySQL installation instructions,
          paying particular attention to the information about setting a
          `root' password. See *Note default-privileges::.

        * Use the *Note `SHOW GRANTS': show-grants.  statement to check
          which accounts have access to what.  Then use the *Note
          `REVOKE': revoke.  statement to remove those privileges that
          are not necessary.

   * Do not store any plain-text passwords in your database. If your
     computer becomes compromised, the intruder can take the full list
     of passwords and use them. Instead, use `MD5()', `SHA1()', or some
     other one-way hashing function and store the hash value.

   * Do not choose passwords from dictionaries. Special programs exist
     to break passwords. Even passwords like `xfish98' are very bad.
     Much better is `duag98' which contains the same word `fish' but
     typed one key to the left on a standard QWERTY keyboard. Another
     method is to use a password that is taken from the first
     characters of each word in a sentence (for example, `Mary had a
     little lamb' results in a password of `Mhall'). The password is
     easy to remember and type, but difficult to guess for someone who
     does not know the sentence.

   * Invest in a firewall. This protects you from at least 50% of all
     types of exploits in any software. Put MySQL behind the firewall
     or in a demilitarized zone (DMZ).

     Checklist:

        * Try to scan your ports from the Internet using a tool such as
          `nmap'. MySQL uses port 3306 by default. This port should not
          be accessible from untrusted hosts. Another simple way to
          check whether or not your MySQL port is open is to try the
          following command from some remote machine, where SERVER_HOST
          is the host name or IP number of the host on which your MySQL
          server runs:

               shell> telnet SERVER_HOST 3306

          If you get a connection and some garbage characters, the port
          is open, and should be closed on your firewall or router,
          unless you really have a good reason to keep it open. If
          `telnet' hangs or the connection is refused, the port is
          blocked, which is how you want it to be.

   * Do not trust any data entered by users of your applications.  They
     can try to trick your code by entering special or escaped
     character sequences in Web forms, URLs, or whatever application
     you have built. Be sure that your application remains secure if a
     user enters something like ``; DROP DATABASE mysql;''. This is an
     extreme example, but large security leaks and data loss might
     occur as a result of hackers using similar techniques, if you do
     not prepare for them.

     A common mistake is to protect only string data values.  Remember
     to check numeric data as well. If an application generates a query
     such as `SELECT * FROM table WHERE ID=234' when a user enters the
     value `234', the user can enter the value `234 OR 1=1' to cause
     the application to generate the query `SELECT * FROM table WHERE
     ID=234 OR 1=1'. As a result, the server retrieves every row in the
     table. This exposes every row and causes excessive server load.
     The simplest way to protect from this type of attack is to use
     single quotes around the numeric constants: `SELECT * FROM table
     WHERE ID='234''. If the user enters extra information, it all
     becomes part of the string. In a numeric context, MySQL
     automatically converts this string to a number and strips any
     trailing non-numeric characters from it.

     Sometimes people think that if a database contains only publicly
     available data, it need not be protected. This is incorrect. Even
     if it is allowable to display any row in the database, you should
     still protect against denial of service attacks (for example,
     those that are based on the technique in the preceding paragraph
     that causes the server to waste resources). Otherwise, your server
     becomes unresponsive to legitimate users.

     Checklist:

        * Try to enter single and double quote marks (``''' and ``"'')
          in all of your Web forms. If you get any kind of MySQL error,
          investigate the problem right away.

        * Try to modify dynamic URLs by adding `%22' (``"''), `%23'
          (``#''), and `%27' (``''') to them.

        * Try to modify data types in dynamic URLs from numeric to
          character types using the characters shown in the previous
          examples. Your application should be safe against these and
          similar attacks.

        * Try to enter characters, spaces, and special symbols rather
          than numbers in numeric fields. Your application should
          remove them before passing them to MySQL or else generate an
          error. Passing unchecked values to MySQL is very dangerous!

        * Check the size of data before passing it to MySQL.

        * Have your application connect to the database using a user
          name different from the one you use for administrative
          purposes. Do not give your applications any access privileges
          they do not need.

   * Many application programming interfaces provide a means of
     escaping special characters in data values. Properly used, this
     prevents application users from entering values that cause the
     application to generate statements that have a different effect
     than you intend:

        * MySQL C API: Use the *Note `mysql_real_escape_string()':
          mysql-real-escape-string.  API call.

        * MySQL++: Use the `escape' and `quote' modifiers for query
          streams.

        * PHP: Use the `mysql_real_escape_string()' function (available
          as of PHP 4.3.0, prior to that PHP version use
          `mysql_escape_string()', and prior to PHP 4.0.3, use
          `addslashes()' ). Note that only `mysql_real_escape_string()'
          is character set-aware; the other functions can be `bypassed'
          when using (invalid) multi-byte character sets. In PHP 5, you
          can use the `mysqli' extension, which supports the improved
          MySQL authentication protocol and passwords, as well as
          prepared statements with placeholders.

        * Perl DBI: Use placeholders or the `quote()' method.

        * Ruby DBI: Use placeholders or the `quote()' method.

        * Java JDBC: Use a `PreparedStatement' object and placeholders.

     Other programming interfaces might have similar capabilities.

   * Do not transmit plain (unencrypted) data over the Internet.  This
     information is accessible to everyone who has the time and ability
     to intercept it and use it for their own purposes.  Instead, use
     an encrypted protocol such as SSL or SSH. MySQL supports internal
     SSL connections as of version 4.0. Another technique is to use SSH
     port-forwarding to create an encrypted (and compressed) tunnel for
     the communication.

   * Learn to use the `tcpdump' and `strings' utilities. In most cases,
     you can check whether MySQL data streams are unencrypted by
     issuing a command like the following:

          shell> tcpdump -l -i eth0 -w - src or dst port 3306 | strings

     This works under Linux and should work with small modifications
     under other systems.

     *Warning*:

     If you do not see plaintext data, this does not always mean that
     the information actually is encrypted. If you need high security,
     you should consult with a security expert.


File: manual.info,  Node: security-against-attack,  Next: privileges-options,  Prev: security-guidelines,  Up: security

5.3.2 Making MySQL Secure Against Attackers
-------------------------------------------

When you connect to a MySQL server, you should use a password. The
password is not transmitted in clear text over the connection.
Password handling during the client connection sequence was upgraded in
MySQL 4.1.1 to be very secure. If you are still using pre-4.1.1-style
passwords, the encryption algorithm is not as strong as the newer
algorithm. With some effort, a clever attacker who can sniff the
traffic between the client and the server can crack the password. (See
*Note password-hashing::, for a discussion of the different password
handling methods.)

MySQL Enterprise

The MySQL Enterprise Monitor enforces best practices for maximizing the
security of your servers. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

All other information is transferred as text, and can be read by anyone
who is able to watch the connection. If the connection between the
client and the server goes through an untrusted network, and you are
concerned about this, you can use the compressed protocol to make
traffic much more difficult to decipher. You can also use MySQL's
internal SSL support to make the connection even more secure. See *Note
secure-connections::. Alternatively, use SSH to get an encrypted TCP/IP
connection between a MySQL server and a MySQL client. You can find an
Open Source SSH client at `http://www.openssh.org/', and a commercial
SSH client at `http://www.ssh.com/'.

To make a MySQL system secure, you should strongly consider the
following suggestions:

   * Require all MySQL accounts to have a password. A client program
     does not necessarily know the identity of the person running it.
     It is common for client/server applications that the user can
     specify any user name to the client program. For example, anyone
     can use the *Note `mysql': mysql. program to connect as any other
     person simply by invoking it as `mysql -u OTHER_USER DB_NAME' if
     OTHER_USER has no password. If all accounts have a password,
     connecting using another user's account becomes much more
     difficult.

     For a discussion of methods for setting passwords, see *Note
     passwords::.

   * Never run the MySQL server as the Unix `root' user. This is
     extremely dangerous, because any user with the `FILE' privilege is
     able to cause the server to create files as `root' (for example,
     `~root/.bashrc'). To prevent this, *Note `mysqld': mysqld. refuses
     to run as `root' unless that is specified explicitly using the
     `--user=root' option.

     *Note `mysqld': mysqld. can (and should) be run as an ordinary,
     unprivileged user instead. You can create a separate Unix account
     named `mysql' to make everything even more secure. Use this
     account only for administering MySQL. To start *Note `mysqld':
     mysqld. as a different Unix user, add a `user' option that
     specifies the user name in the `[mysqld]' group of the `my.cnf'
     option file where you specify server options. For example:

          [mysqld]
          user=mysql

     This causes the server to start as the designated user whether you
     start it manually or by using *Note `mysqld_safe': mysqld-safe. or
     *Note `mysql.server': mysql-server. For more details, see *Note
     changing-mysql-user::.

     Running *Note `mysqld': mysqld. as a Unix user other than `root'
     does not mean that you need to change the `root' user name in the
     `user' table. _User names for MySQL accounts have nothing to do
     with user names for Unix accounts_.

   * Do not allow the use of symlinks to tables. (This capability can
     be disabled with the `--skip-symbolic-links' option.) This is
     especially important if you run *Note `mysqld': mysqld. as `root',
     because anyone that has write access to the server's data directory
     then could delete any file in the system! See *Note
     symbolic-links-to-tables::.

   * Make sure that the only Unix user account with read or write
     privileges in the database directories is the account that is used
     for running *Note `mysqld': mysqld.

   * Do not grant the `PROCESS' or `SUPER' privilege to
     non-administrative users. The output of *Note `mysqladmin
     processlist': mysqladmin. and *Note `SHOW PROCESSLIST':
     show-processlist. shows the text of any statements currently being
     executed, so any user who is allowed to see the server process
     list might be able to see statements issued by other users such as
     `UPDATE user SET password=PASSWORD('not_secure')'.

     *Note `mysqld': mysqld. reserves an extra connection for users who
     have the `SUPER' privilege, so that a MySQL `root' user can log in
     and check server activity even if all normal connections are in
     use.

     The `SUPER' privilege can be used to terminate client connections,
     change server operation by changing the value of system variables,
     and control replication servers.

   * Do not grant the `FILE' privilege to non-administrative users. Any
     user that has this privilege can write a file anywhere in the file
     system with the privileges of the *Note `mysqld': mysqld. daemon.
     To make this a bit safer, files generated with *Note `SELECT ...
     INTO OUTFILE': select. do not overwrite existing files and are
     writable by everyone.

     The `FILE' privilege may also be used to read any file that is
     world-readable or accessible to the Unix user that the server runs
     as. With this privilege, you can read any file into a database
     table. This could be abused, for example, by using *Note `LOAD
     DATA': load-data. to load `/etc/passwd' into a table, which then
     can be displayed with *Note `SELECT': select.

   * If you do not trust your DNS, you should use IP numbers rather
     than host names in the grant tables. In any case, you should be
     very careful about creating grant table entries using host name
     values that contain wildcards.

   * If you want to restrict the number of connections allowed to a
     single account, you can do so by setting the
     `max_user_connections' variable in *Note `mysqld': mysqld. The
     *Note `GRANT': grant. statement also supports resource control
     options for limiting the extent of server use allowed to an
     account. See *Note grant::.


File: manual.info,  Node: privileges-options,  Next: load-data-local,  Prev: security-against-attack,  Up: security

5.3.3 Security-Related `mysqld' Options
---------------------------------------

The following *Note `mysqld': mysqld. options affect security:

*`mysqld' Security Option/Variable Summary*

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
allow-suspicious-udfs         Yes                                                        Yes                                                                                                                                                                                                                                         
automatic_sp_privileges                                                                                                                             Yes                                                                                                                   Global                                                     Yes
chroot                        Yes                                                        Yes                                                                                                                                                                                                                                         
des-key-file                  Yes                                                        Yes                                                                                                                                                                                                                                         
local_infile                                                                                                                                        Yes                                                                                                                   Global                                                     Yes
local-infile                  Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_: local_infile                                                                                                                                                                                                                                                                                                           
old-passwords                 Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: old_passwords                                                                                                                         Yes                                                                                                                   Both                                                       Yes
safe-user-create              Yes                                                        Yes                                                                                                                                                                                                                                         
secure-auth                   Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: secure_auth                                                                                                                           Yes                                                                                                                   Global                                                     Yes
secure-backup-file-priv       Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
secure_backup_file_priv                                                                                                                                                                                                                                                                                                              
secure-file-priv              Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
secure_file_priv                                                                                                                                                                                                                                                                                                                     
skip-grant-tables             Yes                                                        Yes                                                                                                                                                                                                                                         
skip-name-resolve             Yes                                                        Yes                                                                                                                                                                                                                                         
skip-networking               Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: skip_networking                                                                                                                       Yes                                                                                                                   Global                                                     No
skip-show-database            Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
skip_show_database                                                                                                                                                                                                                                                                                                                   

   * `--allow-suspicious-udfs'

     This option controls whether user-defined functions that have only
     an `xxx' symbol for the main function can be loaded. By default,
     the option is off and only UDFs that have at least one auxiliary
     symbol can be loaded; this prevents attempts at loading functions
     from shared object files other than those containing legitimate
     UDFs. See *Note udf-security::.

   *  `--local-infile[={0|1}]'

     If you start the server with `--local-infile=0', clients cannot
     use `LOCAL' in *Note `LOAD DATA': load-data. statements. See *Note
     load-data-local::.

   * `--old-passwords'

     Force the server to generate short (pre-4.1) password hashes for
     new passwords. This is useful for compatibility when the server
     must support older client programs. See *Note password-hashing::.

     MySQL Enterprise

     The MySQL Enterprise Monitor offers advice on the security
     implications of using this option. For subscription information,
     see `http://www.mysql.com/products/enterprise/advisors.html'.

   * `--safe-show-database' (_OBSOLETE_)

     In previous versions of MySQL, this option caused the *Note `SHOW
     DATABASES': show-databases. statement to display the names of only
     those databases for which the user had some kind of privilege. In
     MySQL 6.0, this option is no longer available as this is now the
     default behavior, and there is a *Note `SHOW DATABASES':
     show-databases. privilege that can be used to control access to
     database names on a per-account basis. See *Note grant::.

   * `--safe-user-create'

     If this option is enabled, a user cannot create new MySQL users by
     using the *Note `GRANT': grant.  statement unless the user has the
     `INSERT' privilege for the `mysql.user' table or any column in the
     table. If you want a user to have the ability to create new users
     that have those privileges that the user has the right to grant,
     you should grant the user the following privilege:

          GRANT INSERT(user) ON mysql.user TO 'USER_NAME'@'HOST_NAME';

     This ensures that the user cannot change any privilege columns
     directly, but has to use the *Note `GRANT': grant. statement to
     give privileges to other users.

   * `--secure-auth'

     Disallow authentication for accounts that have old (pre-4.1)
     passwords.

     The *Note `mysql': mysql. client also has a `--secure-auth'
     option, which prevents connections to a server if the server
     requires a password in old format for the client account.

   * `--secure-backup-file-priv=PATH'

     *Command Line        `--secure-backup-file-priv'
     Format*              
     *Config File Format* `secure-backup-file-priv'
     *Option Sets         Yes, `secure_backup_file_priv'
     Variable*            
     *Variable Name*      `secure_backup_file_priv'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     This option limits the effect of the *Note `BACKUP DATABASE':
     backup-database. and *Note `RESTORE': restore.  statements to work
     only with files in the specified directory.  This option was added
     in MySQL 6.0.11; in older releases, use `--secure-file-priv'
     instead.

   * `--secure-file-priv=PATH'

     *Command Line        `--secure-file-priv'
     Format*              
     *Config File Format* `secure-file-priv'
     *Option Sets         Yes, `secure_file_priv'
     Variable*            
     *Variable Name*      `secure_file_priv'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     This option limits the effect of the `LOAD_FILE()' function and the
     *Note `LOAD DATA': load-data. and *Note `SELECT ... INTO OUTFILE':
     select.  statements to work only with files in the specified
     directory.  Before MySQL 6.0.11, it also applies to the *Note
     `BACKUP DATABASE': backup-database. and *Note `RESTORE': restore.
     statements; as of 6.0.11, `--secure-backup-file-priv' applies to
     those statements.

   * `--skip-grant-tables'

     This option causes the server not to use the privilege system at
     all. This gives anyone with access to the server _unrestricted
     access_ to _all databases_. You can cause a running server to start
     using the grant tables again by executing *Note `mysqladmin
     flush-privileges': mysqladmin. or *Note `mysqladmin reload':
     mysqladmin. command from a system shell, or by issuing a MySQL
     *Note `FLUSH PRIVILEGES': flush. statement. This option also
     suppresses loading of plugins and user-defined functions (UDFs).

   * `--skip-name-resolve'

     Host names are not resolved. All `Host' column values in the grant
     tables must be IP numbers or `localhost'.

   * `--skip-networking'

     Do not allow TCP/IP connections over the network. All connections
     to *Note `mysqld': mysqld. must be made via Unix socket files.

   * `--skip-show-database'

     With this option, the *Note `SHOW DATABASES': show-databases.
     statement is allowed only to users who have the `SHOW DATABASES'
     privilege, and the statement displays all database names.  Without
     this option, *Note `SHOW DATABASES': show-databases. is allowed to
     all users, but displays each database name only if the user has the
     `SHOW DATABASES' privilege or some privilege for the database.
     Note that any global privilege is a privilege for the database.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to allow clients
     to connect via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.


File: manual.info,  Node: load-data-local,  Next: changing-mysql-user,  Prev: privileges-options,  Up: security

5.3.4 Security Issues with `LOAD DATA LOCAL'
--------------------------------------------

The *Note `LOAD DATA': load-data. statement can load a file that is
located on the server host, or it can load a file that is located on
the client host when the `LOCAL' keyword is specified.

There are two potential security issues with supporting the `LOCAL'
version of *Note `LOAD DATA': load-data. statements:

   * The transfer of the file from the client host to the server host
     is initiated by the MySQL server. In theory, a patched server
     could be built that would tell the client program to transfer a
     file of the server's choosing rather than the file named by the
     client in the *Note `LOAD DATA': load-data. statement. Such a
     server could access any file on the client host to which the
     client user has read access.

   * In a Web environment where the clients are connecting from a Web
     server, a user could use *Note `LOAD DATA LOCAL': load-data. to
     read any files that the Web server process has read access to
     (assuming that a user could run any command against the SQL
     server). In this environment, the client with respect to the MySQL
     server actually is the Web server, not the remote program being
     run by the user who connects to the Web server.

To deal with these problems, we changed how *Note `LOAD DATA LOCAL':
load-data. is handled as of MySQL 3.23.49 and MySQL 4.0.2 (4.0.13 on
Windows):

   * By default, all MySQL clients and libraries in binary
     distributions are compiled with the `--enable-local-infile'
     option, to be compatible with MySQL 3.23.48 and before.

   * If you build MySQL from source but do not invoke `configure' with
     the `--enable-local-infile' option, *Note `LOAD DATA LOCAL':
     load-data. cannot be used by any client unless it is written
     explicitly to invoke *Note `mysql_options(...
     MYSQL_OPT_LOCAL_INFILE, 0)': mysql-options. See *Note
     mysql-options::.

   * You can disable all *Note `LOAD DATA LOCAL': load-data. commands
     from the server side by starting *Note `mysqld': mysqld. with the
     `--local-infile=0' option.

   * For the *Note `mysql': mysql. command-line client, enable *Note
     `LOAD DATA LOCAL': load-data. by specifying the
     `--local-infile[=1]' option, or disable it with the
     `--local-infile=0' option. For *Note `mysqlimport': mysqlimport,
     local data file loading is off by default; enable it with the
     `--local' or `-L' option. In any case, successful use of a local
     load operation requires that the server is enabled to allow it.

   * If you use *Note `LOAD DATA LOCAL': load-data. in Perl scripts or
     other programs that read the `[client]' group from option files,
     you can add the `local-infile=1' option to that group. However, to
     keep this from causing problems for programs that do not understand
     `local-infile', specify it using the `loose-' prefix:

          [client]
          loose-local-infile=1

   * If *Note `LOAD DATA LOCAL': load-data. is disabled, either in the
     server or the client, a client that attempts to issue such a
     statement receives the following error message:

          ERROR 1148: The used command is not allowed with this MySQL version

MySQL Enterprise

Security advisors notify subscribers to the MySQL Enterprise Monitor
whenever a server is started with the `--local-infile' option enabled.
For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: changing-mysql-user,  Prev: load-data-local,  Up: security

5.3.5 How to Run MySQL as a Normal User
---------------------------------------

On Windows, you can run the server as a Windows service using a normal
user account.

On Unix, the MySQL server *Note `mysqld': mysqld. can be started and
run by any user. However, you should avoid running the server as the
Unix `root' user for security reasons. To change *Note `mysqld':
mysqld. to run as a normal unprivileged Unix user USER_NAME, you must
do the following:

  1. Stop the server if it is running (use *Note `mysqladmin shutdown':
     mysqladmin.).

  2. Change the database directories and files so that USER_NAME has
     privileges to read and write files in them (you might need to do
     this as the Unix `root' user):

          shell> chown -R USER_NAME /PATH/TO/MYSQL/DATADIR

     If you do not do this, the server will not be able to access
     databases or tables when it runs as USER_NAME.

     If directories or files within the MySQL data directory are
     symbolic links, `chown -R' might not follow symbolic links for
     you. If it does not, you will also need to follow those links and
     change the directories and files they point to.

  3. Start the server as user USER_NAME.  Another alternative is to
     start *Note `mysqld': mysqld. as the Unix `root' user and use the
     `--user=USER_NAME' option. *Note `mysqld': mysqld. starts up, then
     switches to run as the Unix user USER_NAME before accepting any
     connections.

  4. To start the server as the given user automatically at system
     startup time, specify the user name by adding a `user' option to
     the `[mysqld]' group of the `/etc/my.cnf' option file or the
     `my.cnf' option file in the server's data directory. For example:

          [mysqld]
          user=USER_NAME

If your Unix machine itself isn't secured, you should assign passwords
to the MySQL `root' accounts in the grant tables. Otherwise, any user
with a login account on that machine can run the *Note `mysql': mysql.
client with a `--user=root' option and perform any operation. (It is a
good idea to assign passwords to MySQL accounts in any case, but
especially so when other login accounts exist on the server host.) See
*Note post-installation::.


File: manual.info,  Node: privilege-system,  Next: user-account-management,  Prev: security,  Up: server-administration

5.4 The MySQL Access Privilege System
=====================================

* Menu:

* privileges-provided::          Privileges Provided by MySQL
* grant-table-structure::        Privilege System Grant Tables
* account-names::                Specifying Account Names
* connection-access::            Access Control, Stage 1: Connection Verification
* request-access::               Access Control, Stage 2: Request Verification
* privilege-changes::            When Privilege Changes Take Effect
* access-denied::                Causes of Access-Denied Errors

The primary function of the MySQL privilege system is to authenticate a
user who connects from a given host and to associate that user with
privileges on a database such as *Note `SELECT': select, *Note
`INSERT': insert, *Note `UPDATE': update, and *Note `DELETE': delete.
Additional functionality includes the ability to have anonymous users
and to grant privileges for MySQL-specific functions such as *Note
`LOAD DATA INFILE': load-data. and administrative operations.

There are some things that you cannot do with the MySQL privilege
system:

   * You cannot explicitly specify that a given user should be denied
     access. That is, you cannot explicitly match a user and then
     refuse the connection.

   * You cannot specify that a user has privileges to create or drop
     tables in a database but not to create or drop the database itself.

   * A password applies globally to an account. You cannot associate a
     password with a specific object such as a database, table, or
     routine.

The user interface to the MySQL privilege system consists of SQL
statements such as *Note `CREATE USER': create-user, *Note `GRANT':
grant, and *Note `REVOKE': revoke. See *Note account-management-sql::.

Internally, the server stores privilege information in the grant tables
of the `mysql' database (that is, in the database named `mysql'). The
MySQL server reads the contents of these tables into memory when it
starts and bases access-control decisions on the in-memory copies of
the grant tables.

The MySQL privilege system ensures that all users may perform only the
operations allowed to them. As a user, when you connect to a MySQL
server, your identity is determined by _the host from which you
connect_ and _the user name you specify_. When you issue requests after
connecting, the system grants privileges according to your identity and
_what you want to do_.

MySQL considers both your host name and user name in identifying you
because there is no reason to assume that a given user name belongs to
the same person on all hosts. For example, the user `joe' who connects
from `office.example.com' need not be the same person as the user `joe'
who connects from `home.example.com'. MySQL handles this by allowing
you to distinguish users on different hosts that happen to have the
same name: You can grant one set of privileges for connections by `joe'
from `office.example.com', and a different set of privileges for
connections by `joe' from `home.example.com'. To see what privileges a
given account has, use the *Note `SHOW GRANTS': show-grants. statement.
For example:

     SHOW GRANTS FOR 'joe'@'office.example.com';
     SHOW GRANTS FOR 'joe'@'home.example.com';

MySQL access control involves two stages when you run a client program
that connects to the server:

*Stage 1:* The server accepts or rejects the connection based on your
identity and whether you can verify your identity by supplying the
correct password.

*Stage 2:* Assuming that you can connect, the server checks each
statement you issue to determine whether you have sufficient privileges
to perform it. For example, if you try to select rows from a table in a
database or drop a table from the database, the server verifies that
you have the `SELECT' privilege for the table or the `DROP' privilege
for the database.

For a more detailed description of what happens during each stage, see
*Note connection-access::, and *Note request-access::.

If your privileges are changed (either by yourself or someone else)
while you are connected, those changes do not necessarily take effect
immediately for the next statement that you issue. For details about
the conditions under which the server reloads the grant tables, see
*Note privilege-changes::.

For general security-related advice, see *Note security::.  For help in
diagnosing privilege-related problems, see *Note access-denied::.


File: manual.info,  Node: privileges-provided,  Next: grant-table-structure,  Prev: privilege-system,  Up: privilege-system

5.4.1 Privileges Provided by MySQL
----------------------------------

MySQL provides privileges that apply in different contexts and at
different levels of operation:

   * Administrative privileges enable users to manage operation of the
     MySQL server. These privileges are global because they are not
     specific to a particular database.

   * Database privileges apply to a database and to all objects within
     it. These privileges can be granted for specific databases, or
     globally so that they apply to all databases.

   * Privileges for database objects such as tables, indexes, views,
     and stored routines can be granted for specific objects within a
     database, for all objects of a given type within a database (for
     example, all tables in a database), or globally for all objects of
     a given type in all databases).

Information about account privileges is stored in the `user', `db',
`host', `tables_priv', `columns_priv', and `procs_priv' tables in the
`mysql' database (see *Note grant-table-structure::). The MySQL server
reads the contents of these tables into memory when it starts and
reloads them under the circumstances indicated in *Note
privilege-changes::. Access-control decisions are based on the
in-memory copies of the grant tables.

Some releases of MySQL introduce changes to the structure of the grant
tables to add new access privileges or features. Whenever you update to
a new version of MySQL, you should update your grant tables to make
sure that they have the current structure so that you can take
advantage of any new capabilities. See *Note mysql-upgrade::.

The following table shows the privilege names used at the SQL level in
the *Note `GRANT': grant. and *Note `REVOKE': revoke. statements, along
with the column name associated with each privilege in the grant tables
and the context in which the privilege applies.

*Privilege*            *Column*                 *Context*
`CREATE'               `Create_priv'            databases, tables, or
                                                indexes
`DROP'                 `Drop_priv'              databases or tables
`GRANT OPTION'         `Grant_priv'             databases, tables, or
                                                stored routines
`REFERENCES'           `References_priv'        databases or tables
`EVENT'                `Event_priv'             databases
`ALTER'                `Alter_priv'             tables
`DELETE'               `Delete_priv'            tables
`INDEX'                `Index_priv'             tables
`INSERT'               `Insert_priv'            tables
`SELECT'               `Select_priv'            tables
`UPDATE'               `Update_priv'            tables
`CREATE TEMPORARY      `Create_tmp_table_priv'  tables
TABLES'                                         
`LOCK TABLES'          `Lock_tables_priv'       tables
`TRIGGER'              `Trigger_priv'           tables
`CREATE VIEW'          `Create_view_priv'       views
`SHOW VIEW'            `Show_view_priv'         views
`ALTER ROUTINE'        `Alter_routine_priv'     stored routines
`CREATE ROUTINE'       `Create_routine_priv'    stored routines
`EXECUTE'              `Execute_priv'           stored routines
`FILE'                 `File_priv'              file access on server host
`CREATE TABLESPACE'    `Create_tablespace_priv' server administration
`CREATE USER'          `Create_user_priv'       server administration
`PROCESS'              `Process_priv'           server administration
`RELOAD'               `Reload_priv'            server administration
`REPLICATION CLIENT'   `Repl_client_priv'       server administration
`REPLICATION SLAVE'    `Repl_slave_priv'        server administration
`SHOW DATABASES'       `Show_db_priv'           server administration
`SHUTDOWN'             `Shutdown_priv'          server administration
`SUPER'                `Super_priv'             server administration
`ALL [PRIVILEGES]'                              server administration
`USAGE'                                         server administration

The following list provides a general description of each privilege
available in MySQL. Particular SQL statements might have more specific
privilege requirements than indicated here. If so, the description for
the statement in question provides the details.

   *  The `ALL' or `ALL PRIVILEGES' privilege specifier is shorthand.
     It stands for `all privileges available at a given privilege level'
     (except `GRANT OPTION'). For example, granting `ALL' at the global
     or table level grants all global privileges or all table-level
     privileges.

   *  The `ALTER' privilege enables use of *Note `ALTER TABLE':
     alter-table. to change the structure of or rename tables. (*Note
     `ALTER TABLE': alter-table. also requires the `INSERT' and
     `CREATE' privileges.)

     MySQL Enterprise

     In some circumstances, the `ALTER' privilege is entirely
     unnecessary -- on slaves where there are no non-replicated tables,
     for instance. The MySQL Enterprise Monitor notifies subscribers
     when accounts have inappropriate privileges. For more information,
     see `http://www.mysql.com/products/enterprise/advisors.html'.

   *  The `ALTER ROUTINE' privilege is needed to alter or drop stored
     routines (procedures and functions).

   *  The `CREATE' privilege enables creation of new databases and
     tables.

   *  The `CREATE ROUTINE' privilege is needed to create stored
     routines (procedures and functions).

   *  The `CREATE TABLESPACE' privilege is needed to create, alter, or
     drop tablespaces and log file groups. This privilege was added in
     MySQL 6.0.7.

   *  The `CREATE TEMPORARY TABLES' privilege enables the use of the
     keyword `TEMPORARY' in *Note `CREATE TABLE': create-table.
     statements.

   *  The `CREATE USER' privilege enables use of *Note `CREATE USER':
     create-user, *Note `DROP USER': drop-user, *Note `RENAME USER':
     rename-user, and *Note `REVOKE ALL PRIVILEGES': revoke.

   *  The `CREATE VIEW' privilege enables use of *Note `CREATE VIEW':
     create-view.

   *  The `DELETE' privilege enables rows to be deleted from tables in
     a database.

   *  The `DROP' privilege enables you to drop (remove) existing
     databases, tables, and views. The `DROP' privilege is required in
     order to use the statement `ALTER TABLE ... DROP PARTITION' on a
     partitioned table. The `DROP' privilege is also required for *Note
     `TRUNCATE TABLE': truncate. _If you grant the `DROP' privilege for
     the `mysql' database to a user, that user can drop the database in
     which the MySQL access privileges are stored._

   *  The `EVENT' privilege is required to create, alter, or drop
     events for the Event Scheduler.

   *  The `EXECUTE' privilege is required to execute stored routines
     (procedures and functions).

   *  The `FILE' privilege gives you permission to read and write files
     on the server host using the *Note `LOAD DATA INFILE': load-data.
     and *Note `SELECT ... INTO OUTFILE': select. statements. A user
     who has the `FILE' privilege can read any file on the server host
     that is either world-readable or readable by the MySQL server.
     (This implies the user can read any file in any database
     directory, because the server can access any of those files.) The
     `FILE' privilege also enables the user to create new files in any
     directory where the MySQL server has write access. As a security
     measure, the server will not overwrite existing files.

   *  The `GRANT OPTION' privilege enables you to give to other users
     or remove from other users those privileges that you yourself
     possess.

   *  The `INDEX' privilege enables you to create or drop (remove)
     indexes.  `INDEX' applies to existing tables. If you have the
     `CREATE' privilege for a table, you can include index definitions
     in the *Note `CREATE TABLE': create-table. statement.

   *  The `INSERT' privilege enables rows to be inserted into tables in
     a database.  `INSERT' is also required for the *Note `ANALYZE
     TABLE': analyze-table, *Note `OPTIMIZE TABLE': optimize-table, and
     *Note `REPAIR TABLE': repair-table. table-maintenance statements.

   *  The `LOCK TABLES' privilege enables the use of explicit *Note
     `LOCK TABLES': lock-tables. statements to lock tables for which
     you have the `SELECT' privilege. This includes the use of write
     locks, which prevents other sessions from reading the locked table.

   *  The `PROCESS' privilege pertains to display of information about
     the threads executing within the server (that is, information
     about the statements being executed by sessions). The privilege
     enables use of *Note `SHOW PROCESSLIST': show-processlist. or
     *Note `mysqladmin processlist': mysqladmin. to see threads
     belonging to other accounts; you can always see your own threads.

   *  The `REFERENCES' privilege currently is unused.

   *  The `RELOAD' privilege enables use of the *Note `FLUSH': flush.
     statement. It also enables *Note `mysqladmin': mysqladmin.
     commands that are equivalent to *Note `FLUSH': flush. operations:
     `flush-hosts', `flush-logs', `flush-privileges', `flush-status',
     `flush-tables', `flush-threads', `refresh', and `reload'.

     The `reload' command tells the server to reload the grant tables
     into memory.  `flush-privileges' is a synonym for `reload'. The
     `refresh' command closes and reopens the log files and flushes all
     tables. The other `flush-XXX' commands perform functions similar to
     `refresh', but are more specific and may be preferable in some
     instances. For example, if you want to flush just the log files,
     `flush-logs' is a better choice than `refresh'.

   *  The `REPLICATION CLIENT' privilege enables the use of *Note `SHOW
     MASTER STATUS': show-master-status. and *Note `SHOW SLAVE STATUS':
     show-slave-status.

   *  The `REPLICATION SLAVE' privilege should be granted to accounts
     that are used by slave servers to connect to the current server as
     their master. Without this privilege, the slave cannot request
     updates that have been made to databases on the master server.

   *  The `SELECT' privilege enables you to select rows from tables in
     a database.  *Note `SELECT': select. statements require the
     `SELECT' privilege only if they actually retrieve rows from a
     table. Some *Note `SELECT': select. statements do not access
     tables and can be executed without permission for any database.
     For example, you can use *Note `SELECT': select. as a simple
     calculator to evaluate expressions that make no reference to
     tables:

          SELECT 1+1;
          SELECT PI()*2;

   *  The `SHOW DATABASES' privilege enables the account to see
     database names by issuing the `SHOW DATABASE' statement. Accounts
     that do not have this privilege see only databases for which they
     have some privileges, and cannot use the statement at all if the
     server was started with the `--skip-show-database' option.  Note
     that _any_ global privilege is a privilege for the database.

     MySQL Enterprise

     The `SHOW DATABASES' privilege should be granted only to users who
     need to see all the databases on a MySQL server. Subscribers to
     the MySQL Enterprise Monitor are alerted when servers are started
     without the `--skip-show-database' option.  For more information,
     see `http://www.mysql.com/products/enterprise/advisors.html'.

   *  The `SHOW VIEW' privilege enables use of *Note `SHOW CREATE
     VIEW': show-create-view.

   *  The `SHUTDOWN' privilege enables use of the *Note `mysqladmin
     shutdown': mysqladmin. command.  There is no corresponding SQL
     statement.

   *  The `SUPER' privilege enables use of *Note `CHANGE MASTER TO':
     change-master-to, *Note `KILL': kill. or *Note `mysqladmin kill':
     mysqladmin. to kill threads belonging to other accounts (you can
     always kill your own threads), *Note `PURGE BINARY LOGS':
     purge-binary-logs, and *Note `SET GLOBAL': set-option. statements,
     the *Note `mysqladmin debug': mysqladmin. command, and allows you
     to connect (once) even if the connection limit controlled by the
     `max_connections' system variable is reached.

     To create or alter stored functions if binary logging is enabled,
     you may also need the `SUPER' privilege, as described in *Note
     stored-programs-logging::.

   *  The `TRIGGER' privilege enables you to create and drop triggers.
     You must have this privilege for a table to create or drop
     triggers for that table.

   *  The `UPDATE' privilege enables rows to be updated in tables in a
     database.

   *  The `USAGE' privilege specifier stands for `no privileges.' It is
     used at the global level with *Note `GRANT': grant. to modify
     account attributes such as resource limits or SSL characteristics
     without affecting existing account privileges.

It is a good idea to grant to an account only those privileges that it
needs. You should exercise particular caution in granting the `FILE'
and administrative privileges:

   * The `FILE' privilege can be abused to read into a database table
     any files that the MySQL server can read on the server host. This
     includes all world-readable files and files in the server's data
     directory.  The table can then be accessed using *Note `SELECT':
     select. to transfer its contents to the client host.

   * The `GRANT OPTION' privilege enables users to give their
     privileges to other users. Two users that have different
     privileges and with the `GRANT OPTION' privilege are able to
     combine privileges.

   * The `ALTER' privilege may be used to subvert the privilege system
     by renaming tables.

   * The `SHUTDOWN' privilege can be abused to deny service to other
     users entirely by terminating the server.

   * The `PROCESS' privilege can be used to view the plain text of
     currently executing statements, including statements that set or
     change passwords.

   * The `SUPER' privilege can be used to terminate other sessions or
     change how the server operates.

   * Privileges granted for the `mysql' database itself can be used to
     change passwords and other access privilege information. Passwords
     are stored encrypted, so a malicious user cannot simply read them
     to know the plain text password. However, a user with write access
     to the `user' table `Password' column can change an account's
     password, and then connect to the MySQL server using that account.

     MySQL Enterprise

     Accounts with unnecessary global privileges constitute a security
     risk. Subscribers to the MySQL Enterprise Monitor are
     automatically alerted to the existence of such accounts.  For
     detailed information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: grant-table-structure,  Next: account-names,  Prev: privileges-provided,  Up: privilege-system

5.4.2 Privilege System Grant Tables
-----------------------------------

Normally, you manipulate the contents of the grant tables indirectly by
using statements such as *Note `GRANT': grant. and *Note `REVOKE':
revoke. to set up accounts and control the privileges available to each
one. See *Note account-management-sql::. The discussion here describes
the underlying structure of the grant tables and how the server uses
their contents when interacting with clients.

Each grant table contains scope columns and privilege columns:

   * Scope columns determine the scope of each row (entry) in the
     tables; that is, the context in which the row applies. For
     example, a `user' table row with `Host' and `User' values of
     `'thomas.loc.gov'' and `'bob'' would be used for authenticating
     connections made to the server from the host `thomas.loc.gov' by a
     client that specifies a user name of `bob'. Similarly, a `db'
     table row with `Host', `User', and `Db' column values of
     `'thomas.loc.gov'', `'bob'' and `'reports'' would be used when
     `bob' connects from the host `thomas.loc.gov' to access the
     `reports' database. The `tables_priv' and `columns_priv' tables
     contain scope columns indicating tables or table/column
     combinations to which each row applies. The `procs_priv' scope
     columns indicate the stored routine to which each row applies.

   * Privilege columns indicate which privileges are granted by a table
     row; that is, what operations can be performed. The server
     combines the information in the various grant tables to form a
     complete description of a user's privileges.  *Note
     request-access::, describes the rules that are used to do this.

The server uses the grant tables in the following manner:

   * The `user' table scope columns determine whether to reject or
     allow incoming connections. For allowed connections, any
     privileges granted in the `user' table indicate the user's global
     (superuser) privileges. Any privilege granted in this table
     applies to _all_ databases on the server.

     *Note*:

     Because any global privilege is considered a privilege for all
     databases, any global privilege enables a user to see all database
     names with *Note `SHOW DATABASES': show-databases. or by examining
     the *Note `SCHEMATA': schemata-table. table of
     `INFORMATION_SCHEMA'.

   * The `db' table scope columns determine which users can access
     which databases from which hosts. The privilege columns determine
     which operations are allowed. A privilege granted at the database
     level applies to the database and to all objects in the database,
     such as tables and stored programs.

   * The `host' table is used in conjunction with the `db' table when
     you want a given `db' table row to apply to several hosts. For
     example, if you want a user to be able to use a database from
     several hosts in your network, leave the `Host' value empty in the
     user's `db' table row, then populate the `host' table with a row
     for each of those hosts. This mechanism is described more detail in
     *Note request-access::.

     *Note*:

     The `host' table must be modified directly with statements such as
     *Note `INSERT': insert, *Note `UPDATE': update, and *Note
     `DELETE': delete. It is not affected by statements such as *Note
     `GRANT': grant. and *Note `REVOKE': revoke. that modify the grant
     tables indirectly. Most MySQL installations need not use this
     table at all.

   * The `tables_priv' and `columns_priv' tables are similar to the
     `db' table, but are more fine-grained: They apply at the table and
     column levels rather than at the database level. A privilege
     granted at the table level applies to the table and to all its
     columns. A privilege granted at the column level applies only to a
     specific column.

   * The `procs_priv' table applies to stored routines. A privilege
     granted at the routine level applies only to a single routine.

The server uses the `user', `db', and `host' tables in the `mysql'
database at both the first and second stages of access control (see
*Note privilege-system::).  The columns in the `user' and `db' tables
are shown here. The `host' table is similar to the `db' table but has a
specialized use as described in *Note request-access::.

*Table Name*                  *user*                 *db*
*Scope columns*               `Host'                 `Host'
                              `User'                 `Db'
                              `Password'             `User'
*Privilege columns*           `Select_priv'          `Select_priv'
                              `Insert_priv'          `Insert_priv'
                              `Update_priv'          `Update_priv'
                              `Delete_priv'          `Delete_priv'
                              `Index_priv'           `Index_priv'
                              `Alter_priv'           `Alter_priv'
                              `Create_priv'          `Create_priv'
                              `Drop_priv'            `Drop_priv'
                              `Grant_priv'           `Grant_priv'
                              `Create_view_priv'     `Create_view_priv'
                              `Show_view_priv'       `Show_view_priv'
                              `Create_routine_priv'  `Create_routine_priv'
                              `Alter_routine_priv'   `Alter_routine_priv'
                              `Execute_priv'         `Execute_priv'
                              `Trigger_priv'         `Trigger_priv'
                              `Event_priv'           `Event_priv'
                              `Create_tmp_table_priv'`Create_tmp_table_priv'
                              `Lock_tables_priv'     `Lock_tables_priv'
                              `References_priv'      `References_priv'
                              `Reload_priv'          
                              `Shutdown_priv'        
                              `Process_priv'         
                              `File_priv'            
                              `Show_db_priv'         
                              `Super_priv'           
                              `Repl_slave_priv'      
                              `Repl_client_priv'     
                              `Create_user_priv'     
                              `Create_tablespace_priv'
*Security columns*            `ssl_type'             
                              `ssl_cipher'           
                              `x509_issuer'          
                              `x509_subject'         
*Resource control columns*    `max_questions'        
                              `max_updates'          
                              `max_connections'      
                              `max_user_connections' 

The `Create_tablespace_priv' column was added in MySQL 6.0.7.

During the second stage of access control, the server performs request
verification to make sure that each client has sufficient privileges
for each request that it issues. In addition to the `user', `db', and
`host' grant tables, the server may also consult the `tables_priv' and
`columns_priv' tables for requests that involve tables. The latter
tables provide finer privilege control at the table and column levels.
They have the columns shown in the following table.

*Table Name*   *tables_priv*  *columns_priv*
*Scope         `Host'         `Host'
columns*                      
               `Db'           `Db'
               `User'         `User'
               `Table_name'   `Table_name'
                              `Column_name'
*Privilege     `Table_priv'   `Column_priv'
columns*                      
               `Column_priv'  
*Other         `Timestamp'    `Timestamp'
columns*                      
               `Grantor'      

The `Timestamp' and `Grantor' columns currently are unused and are
discussed no further here.

For verification of requests that involve stored routines, the server
may consult the `procs_priv' table, which has the columns shown in the
following table.

*Table Name*   *procs_priv*
*Scope         `Host'
columns*       
               `Db'
               `User'
               `Routine_name'
               `Routine_type'
*Privilege     `Proc_priv'
columns*       
*Other         `Timestamp'
columns*       
               `Grantor'

The `Routine_type' column is an *Note `ENUM': enum. column with values
of `'FUNCTION'' or `'PROCEDURE'' to indicate the type of routine the
row refers to. This column enables privileges to be granted separately
for a function and a procedure with the same name.

The `Timestamp' and `Grantor' columns currently are unused and are
discussed no further here.

Scope columns in the grant tables contain strings. They are declared as
shown here; the default value for each is the empty string.

*Column Name*  *Type*
`Host'         `CHAR(60)'
`User'         `CHAR(16)'
`Password'     `CHAR(41)'
`Db'           `CHAR(64)'
`Table_name'   `CHAR(64)'
`Column_name'  `CHAR(64)'
`Routine_name' `CHAR(64)'

For access-checking purposes, comparisons of `User', `Password', `Db',
and `Table_name' values are case sensitive. Comparisons of `Host',
`Column_name', and `Routine_name' values are not case sensitive.

In the `user', `db', and `host' tables, each privilege is listed in a
separate column that is declared as `ENUM('N','Y') DEFAULT 'N''. In
other words, each privilege can be disabled or enabled, with the
default being disabled.

In the `tables_priv', `columns_priv', and `procs_priv' tables, the
privilege columns are declared as *Note `SET': set. columns. Values in
these columns can contain any combination of the privileges controlled
by the table. Only those privileges listed in the column value are
enabled.

*Table Name*   *Column     *Possible Set Elements*
               Name*       
`tables_priv'  `Table_priv'`'Select', 'Insert', 'Update',
                           'Delete', 'Create', 'Drop', 'Grant',
                           'References', 'Index', 'Alter', 'Create
                           View', 'Show view', 'Trigger''
`tables_priv'  `Column_priv'`'Select', 'Insert', 'Update',
                           'References''
`columns_priv' `Column_priv'`'Select', 'Insert', 'Update',
                           'References''
`procs_priv'   `Proc_priv' `'Execute', 'Alter Routine', 'Grant''

Administrative privileges (such as `RELOAD' or `SHUTDOWN') are
specified only in the `user' table. Administrative operations are
operations on the server itself and are not database-specific, so there
is no reason to list these privileges in the other grant tables.
Consequently, to determine whether you can perform an administrative
operation, the server need consult only the `user' table.

The `FILE' privilege also is specified only in the `user' table. It is
not an administrative privilege as such, but your ability to read or
write files on the server host is independent of the database you are
accessing.

The *Note `mysqld': mysqld. server reads the contents of the grant
tables into memory when it starts. You can tell it to reload the tables
by issuing a *Note `FLUSH PRIVILEGES': flush.  statement or executing a
*Note `mysqladmin flush-privileges': mysqladmin. or *Note `mysqladmin
reload': mysqladmin.  command. Changes to the grant tables take effect
as indicated in *Note privilege-changes::.

When you modify an account's privileges, it is a good idea to verify
that the changes set up privileges the way you want. To check the
privileges for a given account, use the *Note `SHOW GRANTS':
show-grants. statement (see *Note show-grants::). For example, to
determine the privileges that are granted to an account with user name
and host name values of `bob' and `pc84.example.com', use this
statement:

     SHOW GRANTS FOR 'bob'@'pc84.example.com';


File: manual.info,  Node: account-names,  Next: connection-access,  Prev: grant-table-structure,  Up: privilege-system

5.4.3 Specifying Account Names
------------------------------

MySQL account names consist of a user name and a host name. This
enables creation of accounts for users with the same name who can
connect from different hosts. This section describes how to write
account names, including special values and wildcard rules.

Within SQL statements such as *Note `CREATE USER': create-user, *Note
`GRANT': grant, and *Note `SET PASSWORD': set-password, account names
are written using the following rules:

   * Syntax for account names is `'USER_NAME'@'HOST_NAME''.

   * An account name consisting only of a user name is equivalent to
     `'USER_NAME'@'%''.  For example, `'me'' is equivalent to
     `'me'@'%''.

   * The user name and host name need not be quoted if they are legal
     as unquoted identifiers. Quotes are necessary to specify a
     USER_NAME string containing special characters (such as ``-''), or
     a HOST_NAME string containing special characters or wildcard
     characters (such as ``%''); for example, `'test-user'@'%.com''.

   * Quote user names and host names as identifiers or as strings,
     using either backticks (```''), single quotes (``'''), or double
     quotes (``"'').

   * The user name and host name parts, if quoted, should be quoted
     separately. That is, write `'me'@'localhost'', not
     `'me@localhost''.

Account names are stored in grant tables using separate columns for the
user name and host name parts:

   * The `user' table contains one row for each account. The `User' and
     `Host' columns store the user name and host name. Another column,
     `Password', stores the account password. This table also indicates
     which global privileges the account has.

   * Other grant tables indicate privileges an account has for
     databases and objects within databases. These tables have `User'
     and `Host' columns to store the account name. Each row in these
     tables associates with the account in the `user' table that has
     the same `User' and `Host' values.

For additional detail about grant table structure, see *Note
grant-table-structure::.

User names and host names have certain special values or wildcard
conventions, as described following.

A user name is either a non-blank value that literally matches the user
name for incoming connection attempts, or a blank value (empty string)
that matches any user name. An account with a blank user name is an
anonymous user. To specify an anonymous user in SQL statements, use a
quoted empty user name part, such as `''@'localhost''.

The host part of an account name can take many forms, and wildcards are
allowed:

   * A host value can be a host name or an IP number.  `'localhost''
     indicates the local host.  `'127.0.0.1'' indicates the loopback
     interface.

   * You can use the wildcard characters ``%'' and ``_'' in host
     values. These have the same meaning as for pattern-matching
     operations performed with the `LIKE' operator. For example, a host
     value of `'%'' matches any host name, whereas a value of
     `'%.mysql.com'' matches any host in the `mysql.com' domain.
     `'192.168.1.%'' matches any host in the 192.168.1 class C network.

     Because you can use IP wildcard values in host values (for
     example, `'192.168.1.%'' to match every host on a subnet), someone
     could try to exploit this capability by naming a host
     `192.168.1.somewhere.com'. To foil such attempts, MySQL disallows
     matching on host names that start with digits and a dot. Thus, if
     you have a host named something like `1.2.example.com', its name
     never matches the host part of account names. An IP wildcard value
     can match only IP numbers, not host names.

     MySQL Enterprise

     An overly broad host specifier such as ``%'' constitutes a security
     risk. The MySQL Enterprise Monitor provides safeguards against
     this kind of vulnerability. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   * For host values specified as IP numbers, you can specify a netmask
     indicating how many address bits to use for the network number.
     The syntax if `HOST_IP/NETMARK'For example:

          CREATE USER 'david'@'192.58.197.0/255.255.255.0';

     This enables `david' to connect from any client host having an IP
     number CLIENT_IP for which the following condition is true:

          CLIENT_IP & NETMASK = HOST_IP

     That is, for the *Note `CREATE USER': create-user.  statement just
     shown:

          CLIENT_IP & 255.255.255.0 = 192.58.197.0

     IP numbers that satisfy this condition and can connect to the
     MySQL server are those in the range from `192.58.197.0' to
     `192.58.197.255'.

     The netmask can only be used to tell the server to use 8, 16, 24,
     or 32 bits of the address. Examples:

        * `192.0.0.0/255.0.0.0': anything on the 192 class A network

        * `192.168.0.0/255.255.0.0': anything on the 192.168 class B
          network

        * `192.168.1.0/255.255.255.0': anything on the 192.168.1 class
          C network

        * `192.168.1.1': only this specific IP

     The following netmask (28 bits) will not work:

          192.168.0.1/255.255.255.240


File: manual.info,  Node: connection-access,  Next: request-access,  Prev: account-names,  Up: privilege-system

5.4.4 Access Control, Stage 1: Connection Verification
------------------------------------------------------

When you attempt to connect to a MySQL server, the server accepts or
rejects the connection based on your identity and whether you can
verify your identity by supplying the correct password. If not, the
server denies access to you completely. Otherwise, the server accepts
the connection, and then enters Stage 2 and waits for requests.

Your identity is based on two pieces of information:

   * The client host from which you connect

   * Your MySQL user name

Identity checking is performed using the three `user' table scope
columns (`Host', `User', and `Password'). The server accepts the
connection only if the `Host' and `User' columns in some `user' table
row match the client host name and user name and the client supplies
the password specified in that row. The rules for allowable `Host' and
`User' values are given in *Note account-names::.

If the `User' column value is non-blank, the user name in an incoming
connection must match exactly. If the `User' value is blank, it matches
any user name.  If the `user' table row that matches an incoming
connection has a blank user name, the user is considered to be an
anonymous user with no name, not a user with the name that the client
actually specified. This means that a blank user name is used for all
further access checking for the duration of the connection (that is,
during Stage 2).

The `Password' column can be blank. This is not a wildcard and does not
mean that any password matches. It means that the user must connect
without specifying a password.

Non-blank `Password' values in the `user' table represent encrypted
passwords. MySQL does not store passwords in plaintext form for anyone
to see.  Rather, the password supplied by a user who is attempting to
connect is encrypted (using the `PASSWORD()' function). The encrypted
password then is used during the connection process when checking
whether the password is correct. (This is done without the encrypted
password ever traveling over the connection.) See *Note user-names::.

From MySQL's point of view, the encrypted password is the _real_
password, so you should never give anyone access to it. In particular,
_do not give non-administrative users read access to tables in the
`mysql' database_.

The following table shows how various combinations of `Host' and `User'
values in the `user' table apply to incoming connections.

`Host' *Value*            `User'      *Allowable Connections*
                          *Value*     
`'thomas.loc.gov''        `'fred''    `fred', connecting from
                                      `thomas.loc.gov'
`'thomas.loc.gov''        `'''        Any user, connecting from
                                      `thomas.loc.gov'
`'%''                     `'fred''    `fred', connecting from any host
`'%''                     `'''        Any user, connecting from any host
`'%.loc.gov''             `'fred''    `fred', connecting from any host in
                                      the `loc.gov' domain
`'x.y.%''                 `'fred''    `fred', connecting from `x.y.net',
                                      `x.y.com', `x.y.edu', and so on;
                                      this is probably not useful
`'144.155.166.177''       `'fred''    `fred', connecting from the host
                                      with IP address `144.155.166.177'
`'144.155.166.%''         `'fred''    `fred', connecting from any host in
                                      the `144.155.166' class C subnet
`'144.155.166.0/255.255.255.0''`'fred''    Same as previous example

It is possible for the client host name and user name of an incoming
connection to match more than one row in the `user' table. The
preceding set of examples demonstrates this: Several of the entries
shown match a connection from `thomas.loc.gov' by `fred'.

When multiple matches are possible, the server must determine which of
them to use. It resolves this issue as follows:

   * Whenever the server reads the `user' table into memory, it sorts
     the rows.

   * When a client attempts to connect, the server looks through the
     rows in sorted order.

   * The server uses the first row that matches the client host name
     and user name.

To see how this works, suppose that the `user' table looks like this:

     +-----------+----------+-
     | Host      | User     | ...
     +-----------+----------+-
     | %         | root     | ...
     | %         | jeffrey  | ...
     | localhost | root     | ...
     | localhost |          | ...
     +-----------+----------+-

When the server reads the table into memory, it orders the rows with
the most-specific `Host' values first.  Literal host names and IP
numbers are the most specific. (The specificity if a literal IP number
is not affected by whether it has a netmask, so `192.168.1.13' and
`192.168.1.0/255.255.255.0' are considered equally specific.) The
pattern `'%'' means `any host' and is least specific. Rows with the same
`Host' value are ordered with the most-specific `User' values first (a
blank `User' value means `any user' and is least specific). For the
`user' table just shown, the result after sorting looks like this:

     +-----------+----------+-
     | Host      | User     | ...
     +-----------+----------+-
     | localhost | root     | ...
     | localhost |          | ...
     | %         | jeffrey  | ...
     | %         | root     | ...
     +-----------+----------+-

When a client attempts to connect, the server looks through the sorted
rows and uses the first match found. For a connection from `localhost'
by `jeffrey', two of the rows from the table match: the one with `Host'
and `User' values of `'localhost'' and `''', and the one with values of
`'%'' and `'jeffrey''. The `'localhost'' row appears first in sorted
order, so that is the one the server uses.

Here is another example. Suppose that the `user' table looks like this:

     +----------------+----------+-
     | Host           | User     | ...
     +----------------+----------+-
     | %              | jeffrey  | ...
     | thomas.loc.gov |          | ...
     +----------------+----------+-

The sorted table looks like this:

     +----------------+----------+-
     | Host           | User     | ...
     +----------------+----------+-
     | thomas.loc.gov |          | ...
     | %              | jeffrey  | ...
     +----------------+----------+-

A connection by `jeffrey' from `thomas.loc.gov' is matched by the first
row, whereas a connection by `jeffrey' from any host is matched by the
second.

*Note*:

It is a common misconception to think that, for a given user name, all
rows that explicitly name that user are used first when the server
attempts to find a match for the connection.  This is not true. The
preceding example illustrates this, where a connection from
`thomas.loc.gov' by `jeffrey' is first matched not by the row
containing `'jeffrey'' as the `User' column value, but by the row with
no user name. As a result, `jeffrey' is authenticated as an anonymous
user, even though he specified a user name when connecting.

If you are able to connect to the server, but your privileges are not
what you expect, you probably are being authenticated as some other
account. To find out what account the server used to authenticate you,
use the `CURRENT_USER()' function. (See *Note information-functions::.)
It returns a value in `USER_NAME@HOST_NAME' format that indicates the
`User' and `Host' values from the matching `user' table row. Suppose
that `jeffrey' connects and issues the following query:

     mysql> SELECT CURRENT_USER();
     +----------------+
     | CURRENT_USER() |
     +----------------+
     | @localhost     |
     +----------------+

The result shown here indicates that the matching `user' table row had
a blank `User' column value. In other words, the server is treating
`jeffrey' as an anonymous user.

Another way to diagnose authentication problems is to print out the
`user' table and sort it by hand to see where the first match is being
made.


File: manual.info,  Node: request-access,  Next: privilege-changes,  Prev: connection-access,  Up: privilege-system

5.4.5 Access Control, Stage 2: Request Verification
---------------------------------------------------

After you establish a connection, the server enters Stage 2 of access
control. For each request that you issue via that connection, the
server determines what operation you want to perform, then checks
whether you have sufficient privileges to do so. This is where the
privilege columns in the grant tables come into play. These privileges
can come from any of the `user', `db', `host', `tables_priv',
`columns_priv', or `procs_priv' tables. (You may find it helpful to
refer to *Note grant-table-structure::, which lists the columns present
in each of the grant tables.)

The `user' table grants privileges that are assigned to you on a global
basis and that apply no matter what the default database is. For
example, if the `user' table grants you the `DELETE' privilege, you can
delete rows from any table in any database on the server host! In other
words, `user' table privileges are superuser privileges. It is wise to
grant privileges in the `user' table only to superusers such as database
administrators. For other users, you should leave all privileges in the
`user' table set to `'N'' and grant privileges at more specific levels
only. You can grant privileges for particular databases, tables,
columns, or routines.

The `db' and `host' tables grant database-specific privileges. Values
in the scope columns of these tables can take the following forms:

   * A blank `User' value in the `db' table matches the anonymous user.
     A non-blank value matches literally; there are no wildcards in
     user names.

   * The wildcard characters ``%'' and ``_'' can be used in the `Host'
     and `Db' columns of either table. These have the same meaning as
     for pattern-matching operations performed with the `LIKE'
     operator. If you want to use either character literally when
     granting privileges, you must escape it with a backslash. For
     example, to include the underscore character (``_'') as part of a
     database name, specify it as ``\_'' in the *Note `GRANT': grant.
     statement.

   * A `'%'' `Host' value in the `db' table means `any host.' A blank
     `Host' value in the `db' table means `consult the `host' table for
     further information' (a process that is described later in this
     section).

   * A `'%'' or blank `Host' value in the `host' table means `any host.'

   * A `'%'' or blank `Db' value in either table means `any database.'

The server reads the `db' and `host' tables into memory and sorts them
at the same time that it reads the `user' table. The server sorts the
`db' table based on the `Host', `Db', and `User' scope columns, and
sorts the `host' table based on the `Host' and `Db' scope columns. As
with the `user' table, sorting puts the most-specific values first and
least-specific values last, and when the server looks for matching
entries, it uses the first match that it finds.

The `tables_priv' `columns_priv', and `procs_priv' tables grant
table-specific, column-specific, and routine-specific privileges.
Values in the scope columns of these tables can take the following
forms:

   * The wildcard characters ``%'' and ``_'' can be used in the `Host'
     column. These have the same meaning as for pattern-matching
     operations performed with the `LIKE' operator.

   * A `'%'' or blank `Host' value means `any host.'

   * The `Db', `Table_name', `Column_name', and `Routine_name' columns
     cannot contain wildcards or be blank.

The server sorts the `tables_priv', `columns_priv', and `procs_priv'
tables based on the `Host', `Db', and `User' columns. This is similar
to `db' table sorting, but simpler because only the `Host' column can
contain wildcards.

The server uses the sorted tables to verify each request that it
receives. For requests that require administrative privileges such as
`SHUTDOWN' or `RELOAD', the server checks only the `user' table row
because that is the only table that specifies administrative
privileges. The server grants access if the row allows the requested
operation and denies access otherwise. For example, if you want to
execute *Note `mysqladmin shutdown': mysqladmin. but your `user' table
row doesn't grant the `SHUTDOWN' privilege to you, the server denies
access without even checking the `db' or `host' tables. (They contain
no `Shutdown_priv' column, so there is no need to do so.)

For database-related requests (*Note `INSERT': insert, *Note `UPDATE':
update, and so on), the server first checks the user's global
(superuser) privileges by looking in the `user' table row. If the row
allows the requested operation, access is granted. If the global
privileges in the `user' table are insufficient, the server determines
the user's database-specific privileges by checking the `db' and `host'
tables:

  1. The server looks in the `db' table for a match on the `Host', `Db',
     and `User' columns. The `Host' and `User' columns are matched to
     the connecting user's host name and MySQL user name. The `Db'
     column is matched to the database that the user wants to access.
     If there is no row for the `Host' and `User', access is denied.

  2. If there is a matching `db' table row and its `Host' column is not
     blank, that row defines the user's database-specific privileges.

  3. If the matching `db' table row's `Host' column is blank, it
     signifies that the `host' table enumerates which hosts should be
     allowed access to the database. In this case, a further lookup is
     done in the `host' table to find a match on the `Host' and `Db'
     columns. If no `host' table row matches, access is denied. If
     there is a match, the user's database-specific privileges are
     computed as the intersection (_not_ the union!) of the privileges
     in the `db' and `host' table entries; that is, the privileges that
     are `'Y'' in both entries. (This way you can grant general
     privileges in the `db' table row and then selectively restrict
     them on a host-by-host basis using the `host' table entries.)

After determining the database-specific privileges granted by the `db'
and `host' table entries, the server adds them to the global privileges
granted by the `user' table. If the result allows the requested
operation, access is granted. Otherwise, the server successively checks
the user's table and column privileges in the `tables_priv' and
`columns_priv' tables, adds those to the user's privileges, and allows
or denies access based on the result. For stored-routine operations, the
server uses the `procs_priv' table rather than `tables_priv' and
`columns_priv'.

Expressed in boolean terms, the preceding description of how a user's
privileges are calculated may be summarized like this:

     global privileges
     OR (database privileges AND host privileges)
     OR table privileges
     OR column privileges
     OR routine privileges

It may not be apparent why, if the global `user' row privileges are
initially found to be insufficient for the requested operation, the
server adds those privileges to the database, table, and column
privileges later. The reason is that a request might require more than
one type of privilege. For example, if you execute an `INSERT INTO ...
SELECT' statement, you need both the `INSERT' and the `SELECT'
privileges. Your privileges might be such that the `user' table row
grants one privilege and the `db' table row grants the other. In this
case, you have the necessary privileges to perform the request, but the
server cannot tell that from either table by itself; the privileges
granted by the entries in both tables must be combined.

The `host' table is not affected by the *Note `GRANT': grant. or *Note
`REVOKE': revoke. statements, so it is unused in most MySQL
installations. If you modify it directly, you can use it for some
specialized purposes, such as to maintain a list of secure servers on
the local network that are granted all privileges.

You can also use the `host' table to indicate hosts that are _not_
secure. Suppose that you have a machine `public.your.domain' that is
located in a public area that you do not consider secure. You can
enable access to all hosts on your network except that machine by using
`host' table entries like this:

     +--------------------+----+-
     | Host               | Db | ...
     +--------------------+----+-
     | public.your.domain | %  | ... (all privileges set to 'N')
     | %.your.domain      | %  | ... (all privileges set to 'Y')
     +--------------------+----+-


File: manual.info,  Node: privilege-changes,  Next: access-denied,  Prev: request-access,  Up: privilege-system

5.4.6 When Privilege Changes Take Effect
----------------------------------------

When *Note `mysqld': mysqld. starts, it reads all grant table contents
into memory. The in-memory tables become effective for access control
at that point.

If you modify the grant tables indirectly using account-management
statements such as *Note `GRANT': grant, *Note `REVOKE': revoke, or
*Note `SET PASSWORD': set-password, the server notices these changes
and loads the grant tables into memory again immediately.

If you modify the grant tables directly using statements such as *Note
`INSERT': insert, *Note `UPDATE': update, or *Note `DELETE': delete,
your changes have no effect on privilege checking until you either
restart the server or tell it to reload the tables. If you change the
grant tables directly but forget to reload them, your changes have _no
effect_ until you restart the server. This may leave you wondering why
your changes do not seem to make any difference!

To tell the sever to reload the grant tables, perform a
flush-privileges operation. This can be done by issuing a *Note `FLUSH
PRIVILEGES': flush.  statement or by executing a *Note `mysqladmin
flush-privileges': mysqladmin. or *Note `mysqladmin reload': mysqladmin.
command.

When the server reloads the grant tables, privileges for each existing
client connection are affected as follows:

   * Table and column privilege changes take effect with the client's
     next request.

   * Database privilege changes take effect the next time the client
     executes a `USE DB_NAME' statement.

     *Note*:

     Client applications may cache the database name; thus, this effect
     may not be visible to them without actually changing to a
     different database or flushing the privileges.

   * Global privileges and passwords are unaffected for a connected
     client. These changes take effect only for subsequent connections.

If the server is started with the `--skip-grant-tables' option, it does
not read the grant tables or implement any access control. Anyone can
connect and do anything. To cause a server thus started to read the
tables and enable access checking, flush the privileges.


File: manual.info,  Node: access-denied,  Prev: privilege-changes,  Up: privilege-system

5.4.7 Causes of Access-Denied Errors
------------------------------------

If you encounter problems when you try to connect to the MySQL server,
the following items describe some courses of action you can take to
correct the problem.

   * Make sure that the server is running. If it is not, clients cannot
     connect to it. For example, if an attempt to connect to the server
     fails with a message such as one of those following, one cause
     might be that the server is not running:

          shell> mysql
          ERROR 2003: Can't connect to MySQL server on 'HOST_NAME' (111)
          shell> mysql
          ERROR 2002: Can't connect to local MySQL server through socket
          '/tmp/mysql.sock' (111)

   * It might be that the server is running, but you are trying to
     connect using a TCP/IP port, named pipe, or Unix socket file
     different from the one on which the server is listening. To
     correct this when you invoke a client program, specify a `--port'
     option to indicate the proper port number, or a `--socket' option
     to indicate the proper named pipe or Unix socket file. To find out
     where the socket file is, you can use this command:

          shell> netstat -ln | grep mysql

   * Make sure that the server has not been configured to ignore
     network connections or (if you are attempting to connect remotely)
     that it has not been configured to listen only locally on its
     network interfaces. If the server was started with
     `--skip-networking', it will not accept TCP/IP connections at all.
     If the server was started with `--bind-address=127.0.0.1', it will
     listen for TCP/IP connections only locally on the loopback
     interface and will not accept remote connections.

   * Check to make sure that there is no firewall blocking access to
     MySQL. Your firewall may be configured on the basis of the
     application being executed, or the port number used by MySQL for
     communication (3306 by default). Under Linux or Unix, check your
     IP tables (or similar) configuration to ensure that the port has
     not been blocked. Under Windows, applications such as ZoneAlarm or
     the Windows XP personal firewall may need to be configured not to
     block the MySQL port.

   * The grant tables must be properly set up so that the server can
     use them for access control. For some distribution types (such as
     binary distributions on Windows, or RPM distributions on Linux),
     the installation process initializes the `mysql' database
     containing the grant tables.  For distributions that do not do
     this, you must initialize the grant tables manually by running the
     *Note `mysql_install_db': mysql-install-db. script. For details,
     see *Note unix-post-installation::.

     To determine whether you need to initialize the grant tables, look
     for a `mysql' directory under the data directory. (The data
     directory normally is named `data' or `var' and is located under
     your MySQL installation directory.) Make sure that you have a file
     named `user.MYD' in the `mysql' database directory. If not,
     execute the *Note `mysql_install_db': mysql-install-db. script.
     After running this script and starting the server, test the initial
     privileges by executing this command:

          shell> mysql -u root test

     The server should let you connect without error.

   * After a fresh installation, you should connect to the server and
     set up your users and their access permissions:

          shell> mysql -u root mysql

     The server should let you connect because the MySQL `root' user
     has no password initially. That is also a security risk, so
     setting the password for the `root' accounts is something you
     should do while you're setting up your other MySQL accounts. For
     instructions on setting the initial passwords, see *Note
     default-privileges::.

     MySQL Enterprise

     The MySQL Enterprise Monitor enforces security-related best
     practices. For example, subscribers are alerted whenever there is
     any account without a password. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   * If you have updated an existing MySQL installation to a newer
     version, did you run the *Note `mysql_upgrade': mysql-upgrade.
     script? If not, do so. The structure of the grant tables changes
     occasionally when new capabilities are added, so after an upgrade
     you should always make sure that your tables have the current
     structure. For instructions, see *Note mysql-upgrade::.

   * If a client program receives the following error message when it
     tries to connect, it means that the server expects passwords in a
     newer format than the client is capable of generating:

          shell> mysql
          Client does not support authentication protocol requested
          by server; consider upgrading MySQL client

     For information on how to deal with this, see *Note
     password-hashing::, and *Note old-client::.

   * Remember that client programs use connection parameters specified
     in option files or environment variables. If a client program
     seems to be sending incorrect default connection parameters when
     you have not specified them on the command line, check any
     applicable option files and your environment. For example, if you
     get `Access denied' when you run a client without any options,
     make sure that you have not specified an old password in any of
     your option files!

     You can suppress the use of option files by a client program by
     invoking it with the `--no-defaults' option. For example:

          shell> mysqladmin --no-defaults -u root version

     The option files that clients use are listed in *Note
     option-files::. Environment variables are listed in *Note
     environment-variables::.

   * If you get the following error, it means that you are using an
     incorrect `root' password:

          shell> mysqladmin -u root -pXXXX ver
          Access denied for user 'root'@'localhost' (using password: YES)

     If the preceding error occurs even when you have not specified a
     password, it means that you have an incorrect password listed in
     some option file. Try the `--no-defaults' option as described in
     the previous item.

     For information on changing passwords, see *Note passwords::.

     If you have lost or forgotten the `root' password, see *Note
     resetting-permissions::.

   * If you change a password by using *Note `SET PASSWORD':
     set-password, *Note `INSERT': insert, or *Note `UPDATE': update,
     you must encrypt the password using the `PASSWORD()' function. If
     you do not use `PASSWORD()' for these statements, the password
     will not work. For example, the following statement assigns a
     password, but fails to encrypt it, so the user is not able to
     connect afterward:

          SET PASSWORD FOR 'abe'@'HOST_NAME' = 'eagle';

     Instead, set the password like this:

          SET PASSWORD FOR 'abe'@'HOST_NAME' = PASSWORD('eagle');

     The `PASSWORD()' function is unnecessary when you specify a
     password using the *Note `CREATE USER': create-user. or *Note
     `GRANT': grant. statements or the *Note `mysqladmin password':
     mysqladmin. command. Each of those automatically uses `PASSWORD()'
     to encrypt the password. See *Note passwords::, and *Note
     create-user::.

   * `localhost' is a synonym for your local host name, and is also the
     default host to which clients try to connect if you specify no
     host explicitly.

     To avoid this problem on such systems, you can use a
     `--host=127.0.0.1' option to name the server host explicitly. This
     will make a TCP/IP connection to the local *Note `mysqld': mysqld.
     server. You can also use TCP/IP by specifying a `--host' option
     that uses the actual host name of the local host. In this case,
     the host name must be specified in a `user' table row on the
     server host, even though you are running the client program on the
     same host as the server.

   * The `Access denied' error message tells you who you are trying to
     log in as, the client host from which you are trying to connect,
     and whether you were using a password. Normally, you should have
     one row in the `user' table that exactly matches the host name and
     user name that were given in the error message. For example, if
     you get an error message that contains `using password: NO', it
     means that you tried to log in without a password.

   * If you get an `Access denied' error when trying to connect to the
     database with `mysql -u USER_NAME', you may have a problem with
     the `user' table. Check this by executing `mysql -u root mysql'
     and issuing this SQL statement:

          SELECT * FROM user;

     The result should include a row with the `Host' and `User' columns
     matching your client's host name and your MySQL user name.

   * If the following error occurs when you try to connect from a host
     other than the one on which the MySQL server is running, it means
     that there is no row in the `user' table with a `Host' value that
     matches the client host:

          Host ... is not allowed to connect to this MySQL server

     You can fix this by setting up an account for the combination of
     client host name and user name that you are using when trying to
     connect.

     If you do not know the IP number or host name of the machine from
     which you are connecting, you should put a row with `'%'' as the
     `Host' column value in the `user' table. After trying to connect
     from the client machine, use a `SELECT USER()' query to see how
     you really did connect. Then change the `'%'' in the `user' table
     row to the actual host name that shows up in the log. Otherwise,
     your system is left insecure because it allows connections from
     any host for the given user name.

     On Linux, another reason that this error might occur is that you
     are using a binary MySQL version that is compiled with a different
     version of the `glibc' library than the one you are using. In this
     case, you should either upgrade your operating system or `glibc',
     or download a source distribution of MySQL version and compile it
     yourself. A source RPM is normally trivial to compile and install,
     so this is not a big problem.

   * If you specify a host name when trying to connect, but get an
     error message where the host name is not shown or is an IP number,
     it means that the MySQL server got an error when trying to resolve
     the IP number of the client host to a name:

          shell> mysqladmin -u root -pXXXX -h SOME_HOSTNAME ver
          Access denied for user 'root'@'' (using password: YES)

     If you try to connect as `root' and get the following error, it
     means that you do not have a row in the `user' table with a `User'
     column value of `'root'' and that *Note `mysqld': mysqld. cannot
     resolve the host name for your client:

          Access denied for user ''@'unknown'

     These errors indicate a DNS problem. To fix it, execute *Note
     `mysqladmin flush-hosts': mysqladmin. to reset the internal DNS
     host name cache. See *Note dns::.

     Some permanent solutions are:

        * Determine what is wrong with your DNS server and fix it.

        * Specify IP numbers rather than host names in the MySQL grant
          tables.

        * Put an entry for the client machine name in `/etc/hosts' on
          Unix or `\windows\hosts' on Windows.

        * Start *Note `mysqld': mysqld. with the `--skip-name-resolve'
          option.

        * Start *Note `mysqld': mysqld. with the `--skip-host-cache'
          option.

        * On Unix, if you are running the server and the client on the
          same machine, connect to `localhost'.  Unix connections to
          `localhost' use a Unix socket file rather than TCP/IP.

        * On Windows, if you are running the server and the client on
          the same machine and the server supports named pipe
          connections, connect to the host name `.' (period).
          Connections to `.' use a named pipe rather than TCP/IP.

   * If `mysql -u root test' works but `mysql -h YOUR_HOSTNAME -u root
     test' results in `Access denied' (where YOUR_HOSTNAME is the
     actual host name of the local host), you may not have the correct
     name for your host in the `user' table. A common problem here is
     that the `Host' value in the `user' table row specifies an
     unqualified host name, but your system's name resolution routines
     return a fully qualified domain name (or vice versa). For example,
     if you have an entry with host `'pluto'' in the `user' table, but
     your DNS tells MySQL that your host name is `'pluto.example.com'',
     the entry does not work. Try adding an entry to the `user' table
     that contains the IP number of your host as the `Host' column
     value.  (Alternatively, you could add an entry to the `user' table
     with a `Host' value that contains a wildcard; for example,
     `'pluto.%''. However, use of `Host' values ending with ``%'' is
     _insecure_ and is _not_ recommended!)

   * If `mysql -u USER_NAME test' works but `mysql -u USER_NAME
     OTHER_DB' does not, you have not granted access to the given user
     for the database named OTHER_DB.

   * If `mysql -u USER_NAME' works when executed on the server host,
     but `mysql -h HOST_NAME -u USER_NAME' does not work when executed
     on a remote client host, you have not enabled access to the server
     for the given user name from the remote host.

   * If you cannot figure out why you get `Access denied', remove from
     the `user' table all entries that have `Host' values containing
     wildcards (entries that contain `'%'' or `'_'' characters).  A
     very common error is to insert a new entry with `Host'=`'%'' and
     `User'=`'SOME_USER'', thinking that this allows you to specify
     `localhost' to connect from the same machine.  The reason that
     this does not work is that the default privileges include an entry
     with `Host'=`'localhost'' and `User'=`'''. Because that entry has
     a `Host' value `'localhost'' that is more specific than `'%'', it
     is used in preference to the new entry when connecting from
     `localhost'! The correct procedure is to insert a second entry with
     `Host'=`'localhost'' and `User'=`'SOME_USER'', or to delete the
     entry with `Host'=`'localhost'' and `User'=`'''. After deleting
     the entry, remember to issue a *Note `FLUSH PRIVILEGES': flush.
     statement to reload the grant tables. See also *Note
     connection-access::.

   * If you are able to connect to the MySQL server, but get an `Access
     denied' message whenever you issue a *Note `SELECT ... INTO
     OUTFILE': select. or *Note `LOAD DATA INFILE': load-data.
     statement, your account does not have the `FILE' privilege.

   * If you change the grant tables directly (for example, by using
     *Note `INSERT': insert, *Note `UPDATE': update, or *Note `DELETE':
     delete. statements) and your changes seem to be ignored, remember
     that you must execute a *Note `FLUSH PRIVILEGES': flush. statement
     or a *Note `mysqladmin flush-privileges': mysqladmin. command to
     cause the server to reload the privilege tables. Otherwise, your
     changes have no effect until the next time the server is
     restarted. Remember that after you change the `root' password with
     an *Note `UPDATE': update. command, you will not need to specify
     the new password until after you flush the privileges, because the
     server will not know you've changed the password yet!

   * If your privileges seem to have changed in the middle of a
     session, it may be that a MySQL administrator has changed them.
     Reloading the grant tables affects new client connections, but it
     also affects existing connections as indicated in *Note
     privilege-changes::.

   * If you have access problems with a Perl, PHP, Python, or ODBC
     program, try to connect to the server with `mysql -u USER_NAME
     DB_NAME' or `mysql -u USER_NAME -pYOUR_PASS DB_NAME'. If you are
     able to connect using the *Note `mysql': mysql. client, the
     problem lies with your program, not with the access privileges.
     (There is no space between `-p' and the password; you can also use
     the `--password=YOUR_PASS' syntax to specify the password. If you
     use the `-p' or `--password' option with no password value, MySQL
     prompts you for the password.)

   * For testing purposes, start the *Note `mysqld': mysqld.  server
     with the `--skip-grant-tables' option.  Then you can change the
     MySQL grant tables and use the *Note `mysqlaccess': mysqlaccess.
     script to check whether your modifications have the desired
     effect. When you are satisfied with your changes, execute *Note
     `mysqladmin flush-privileges': mysqladmin. to tell the *Note
     `mysqld': mysqld. server to reload the privileges.  This enables
     you to begin using the new grant table contents without stopping
     and restarting the server.

   * If you get the following error, you may have a problem with the
     `db' or `host' table:

          Access to database denied

     If the entry selected from the `db' table has an empty value in
     the `Host' column, make sure that there are one or more
     corresponding entries in the `host' table specifying which hosts
     the `db' table entry applies to. This problem occurs infrequently
     because the `host' table is rarely used.

   * If everything else fails, start the *Note `mysqld': mysqld.
     server with a debugging option (for example,
     `--debug=d,general,query'). This prints host and user information
     about attempted connections, as well as information about each
     command issued. See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * If you have any other problems with the MySQL grant tables and
     feel you must post the problem to the mailing list, always provide
     a dump of the MySQL grant tables. You can dump the tables with the
     *Note `mysqldump mysql': mysqldump. command. To file a bug report,
     see the instructions at *Note bug-reports::. In some cases, you
     may need to restart *Note `mysqld': mysqld. with
     `--skip-grant-tables' to run *Note `mysqldump': mysqldump.


File: manual.info,  Node: user-account-management,  Next: multiple-servers,  Prev: privilege-system,  Up: server-administration

5.5 MySQL User Account Management
=================================

* Menu:

* user-names::                   User Names and Passwords
* adding-users::                 Adding User Accounts
* removing-users::               Removing User Accounts
* user-resources::               Limiting Account Resources
* passwords::                    Assigning Account Passwords
* password-security::            Password Security in MySQL
* secure-connections::           Using SSL for Secure Connections
* windows-and-ssh::              Connecting to MySQL Remotely from Windows with SSH
* account-activity-auditing::    Auditing MySQL Account Activity

This section describes how to set up accounts for clients of your MySQL
server. It discusses the following topics:

   * The meaning of account names and passwords as used in MySQL and
     how that compares to names and passwords used by your operating
     system

   * How to set up new accounts and remove existing accounts

   * How to change passwords

   * Guidelines for using passwords securely

   * How to use secure connections with SSL

See also *Note account-management-sql::, which describes the syntax and
use for all user-management SQL statements.


File: manual.info,  Node: user-names,  Next: adding-users,  Prev: user-account-management,  Up: user-account-management

5.5.1 User Names and Passwords
------------------------------

A MySQL account is defined in terms of a user name and the client host
or hosts from which the user can connect to the server. The account
also has a password. There are several distinctions between the way
user names and passwords are used by MySQL and the way they are used by
your operating system:

   * User names, as used by MySQL for authentication purposes, have
     nothing to do with user names (login names) as used by Windows or
     Unix. On Unix, most MySQL clients by default try to log in using
     the current Unix user name as the MySQL user name, but that is for
     convenience only. The default can be overridden easily, because
     client programs allow any user name to be specified with a `-u' or
     `--user' option. Because this means that anyone can attempt to
     connect to the server using any user name, you cannot make a
     database secure in any way unless all MySQL accounts have
     passwords. Anyone who specifies a user name for an account that
     has no password is able to connect successfully to the server.

   * MySQL user names can be up to 16 characters long. Operating system
     user names, because they are completely unrelated to MySQL user
     names, may be of a different maximum length. For example, Unix
     user names typically are limited to eight characters.

     *Warning*:

     The limit on MySQL user name length is hard-coded in the MySQL
     servers and clients, and trying to circumvent it by modifying the
     definitions of the tables in the `mysql' database _does not work_.

     You should never alter any of the tables in the `mysql' database
     in any manner whatsoever except by means of the procedure that is
     described in *Note mysql-upgrade::. Attempting to redefine MySQL's
     system tables in any other fashion results in undefined (and
     unsupported!) behavior.

   * MySQL passwords have nothing to do with passwords for logging in
     to your operating system. There is no necessary connection between
     the password you use to log in to a Windows or Unix machine and
     the password you use to access the MySQL server on that machine.

   * MySQL encrypts passwords using its own algorithm. This encryption
     is the same as that implemented by the `PASSWORD()' SQL function
     but differs from that used during the Unix login process. Unix
     password encryption is the same as that implemented by the
     `ENCRYPT()' SQL function. See the descriptions of the `PASSWORD()'
     and `ENCRYPT()' functions in *Note encryption-functions::.

     From version 4.1 on, MySQL employs a stronger authentication
     method that has better password protection during the connection
     process than in earlier versions. It is secure even if TCP/IP
     packets are sniffed or the `mysql' database is captured. (In
     earlier versions, even though passwords are stored in encrypted
     form in the `user' table, knowledge of the encrypted password
     value could be used to connect to the MySQL server.)  *Note
     password-hashing::, discusses password encryption further.

When you install MySQL, the grant tables are populated with an initial
set of accounts. These accounts have names and access privileges that
are described in *Note default-privileges::, which also discusses how to
assign passwords to them. Thereafter, you normally set up, modify, and
remove MySQL accounts using statements such as *Note `GRANT': grant. and
*Note `REVOKE': revoke. See *Note account-management-sql::.

When you connect to a MySQL server with a command-line client, you
should specify the user name and password for the account that you want
to use:

     shell> mysql --user=monty --password=GUESS DB_NAME

If you prefer short options, the command looks like this:

     shell> mysql -u monty -pGUESS DB_NAME

There must be _no space_ between the `-p' option and the following
password value. For additional information about specifying user names,
passwords, and other connection parameters, see *Note connecting::.


File: manual.info,  Node: adding-users,  Next: removing-users,  Prev: user-names,  Up: user-account-management

5.5.2 Adding User Accounts
--------------------------

You can create MySQL accounts in two ways:

   * By using statements intended for creating accounts, such as *Note
     `CREATE USER': create-user. or *Note `GRANT': grant. These
     statements cause the server to make appropriate modifications to
     the grant tables.

   * By manipulating the MySQL grant tables directly with statements
     such as *Note `INSERT': insert, *Note `UPDATE': update, or *Note
     `DELETE': delete.

The preferred method is to use account-creation statements because they
are more concise and less error-prone than manipulating the grant
tables directly. *Note `CREATE USER': create-user.  and *Note `GRANT':
grant. are described in *Note account-management-sql::.

Another option for creating accounts is to use one of several available
third-party programs that offer capabilities for MySQL account
administration. `phpMyAdmin' is one such program.

The following examples show how to use the *Note `mysql': mysql. client
program to set up new accounts.  These examples assume that privileges
have been set up according to the defaults described in *Note
default-privileges::.  This means that to make changes, you must
connect to the MySQL server as the MySQL `root' user, and the `root'
account must have the `INSERT' privilege for the `mysql' database and
the `RELOAD' administrative privilege.

As noted in the examples where appropriate, some of the statements will
fail if the server's SQL mode has been set to enable certain
restrictions. In particular, strict mode (`STRICT_TRANS_TABLES',
`STRICT_ALL_TABLES') and `NO_AUTO_CREATE_USER' will prevent the server
from accepting some of the statements. Workarounds are indicated for
these cases. For more information about SQL modes and their effect on
grant table manipulation, see *Note server-sql-mode::, and *Note
grant::.

First, use the *Note `mysql': mysql. program to connect to the server
as the MySQL `root' user:

     shell> mysql --user=root mysql

If you have assigned a password to the `root' account, you'll also need
to supply a `--password' or `-p' option, both for this *Note `mysql':
mysql. command and for those later in this section.

After connecting to the server as `root', you can add new accounts. The
following statements use *Note `GRANT': grant. to set up four new
accounts:

     mysql> CREATE USER 'monty'@'localhost' IDENTIFIED BY 'some_pass';
     mysql> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'localhost'
         ->     WITH GRANT OPTION;
     mysql> CREATE USER 'monty'@'%' IDENTIFIED BY 'some_pass';
     mysql> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'%'
         ->     WITH GRANT OPTION;
     mysql> CREATE USER 'admin'@'localhost';
     mysql> GRANT RELOAD,PROCESS ON *.* TO 'admin'@'localhost';
     mysql> CREATE USER 'dummy'@'localhost';

The accounts created by these statements have the following properties:

   * Two of the accounts have a user name of `monty' and a password of
     `some_pass'. Both accounts are superuser accounts with full
     privileges to do anything. The `'monty'@'localhost'' account can
     be used only when connecting from the local host. The
     `'monty'@'%'' account uses the `'%'' wildcard for the host part,
     so it can be used to connect from any host.

     It is necessary to have both accounts for `monty' to be able to
     connect from anywhere as `monty'. Without the `localhost' account,
     the anonymous-user account for `localhost' that is created by
     *Note `mysql_install_db': mysql-install-db. would take precedence
     when `monty' connects from the local host. As a result, `monty'
     would be treated as an anonymous user. The reason for this is that
     the anonymous-user account has a more specific `Host' column value
     than the `'monty'@'%'' account and thus comes earlier in the
     `user' table sort order.  (`user' table sorting is discussed in
     *Note connection-access::.)

   * The `'admin'@'localhost'' account has no password. This account
     can be used only by `admin' to connect from the local host. It is
     granted the `RELOAD' and `PROCESS' administrative privileges.
     These privileges allow the `admin' user to execute the *Note
     `mysqladmin reload': mysqladmin, *Note `mysqladmin refresh':
     mysqladmin, and *Note `mysqladmin flush-XXX': mysqladmin.
     commands, as well as *Note `mysqladmin processlist': mysqladmin .
     No privileges are granted for accessing any databases. You could
     add such privileges later by issuing additional *Note `GRANT':
     grant. statements.

   * The `'dummy'@'localhost'' account has no password. This account
     can be used only to connect from the local host. No privileges are
     granted. It is assumed that you will grant specific privileges to
     the account later.

The statements that create accounts with no password will fail if the
`NO_AUTO_CREATE_USER' SQL mode is enabled. To deal with this, use an
`IDENTIFIED BY' clause that specifies a non-empty password.

To check the privileges for an account, use *Note `SHOW GRANTS':
show-grants.:

     mysql> SHOW GRANTS FOR 'admin'@'localhost';
     +-----------------------------------------------------+
     | Grants for admin@localhost                          |
     +-----------------------------------------------------+
     | GRANT RELOAD, PROCESS ON *.* TO 'admin'@'localhost' |
     +-----------------------------------------------------+

As an alternative to *Note `CREATE USER': create-user.  and *Note
`GRANT': grant, you can create the same accounts directly by issuing
*Note `INSERT': insert.  statements and then telling the server to
reload the grant tables using *Note `FLUSH PRIVILEGES': flush.:

     shell> mysql --user=root mysql
     mysql> INSERT INTO user
         ->     VALUES('localhost','monty',PASSWORD('some_pass'),
         ->     'Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y');
     mysql> INSERT INTO user
         ->     VALUES('%','monty',PASSWORD('some_pass'),
         ->     'Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y',
         ->     'Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y',
         ->     '','','','',0,0,0,0);
     mysql> INSERT INTO user SET Host='localhost',User='admin',
         ->     Reload_priv='Y', Process_priv='Y';
     mysql> INSERT INTO user (Host,User,Password)
         ->     VALUES('localhost','dummy','');
     mysql> FLUSH PRIVILEGES;

When you create accounts with *Note `INSERT': insert, it is necessary
to use *Note `FLUSH PRIVILEGES': flush.  to tell the server to reload
the grant tables. Otherwise, the changes go unnoticed until you restart
the server. With *Note `CREATE USER': create-user, *Note `FLUSH
PRIVILEGES': flush.  is unnecessary.

The reason for using the `PASSWORD()' function with *Note `INSERT':
insert. is to encrypt the password. The *Note `CREATE USER':
create-user.  statement encrypts the password for you, so `PASSWORD()'
is unnecessary.

The `'Y'' values enable privileges for the accounts. Depending on your
MySQL version, you may have to use a different number of `'Y'' values
in the first two *Note `INSERT': insert. statements. The *Note
`INSERT': insert. statement for the `admin' account employs the more
readable extended *Note `INSERT': insert. syntax using `SET'.

In the *Note `INSERT': insert. statement for the `dummy' account, only
the `Host', `User', and `Password' columns in the `user' table row are
assigned values. None of the privilege columns are set explicitly, so
MySQL assigns them all the default value of `'N''. This is equivalent
to what *Note `CREATE USER': create-user. does.

If strict SQL mode is enabled, all columns that have no default value
must have a value specified. In this case, *Note `INSERT': insert.
statements must explicitly specify values for the `ssl_cipher',
`x509_issuer', and `x509_subject' columns.

To set up a superuser account, it is necessary only to create a `user'
table entry with the privilege columns set to `'Y''. The `user' table
privileges are global, so no entries in any of the other grant tables
are needed.

The next examples create three accounts and give them access to
specific databases. Each of them has a user name of `custom' and
password of `obscure'.

To create the accounts with *Note `CREATE USER': create-user. and *Note
`GRANT': grant, use the following statements:

     shell> mysql --user=root mysql
     mysql> CREATE USER 'custom'@'localhost' IDENTIFIED BY 'obscure';
     mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
         ->     ON bankaccount.*
         ->     TO 'custom'@'localhost';
     mysql> CREATE USER 'custom'@'host47.example.com' IDENTIFIED BY 'obscure';
     mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
         ->     ON expenses.*
         ->     TO 'custom'@'host47.example.com';
     mysql> CREATE USER 'custom'@'server.domain' IDENTIFIED BY 'obscure';
     mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
         ->     ON customer.*
         ->     TO 'custom'@'server.domain';

The three accounts can be used as follows:

   * The first account can access the `bankaccount' database, but only
     from the local host.

   * The second account can access the `expenses' database, but only
     from the host `host47.example.com'.

   * The third account can access the `customer' database, but only
     from the host `server.domain'.

To set up the `custom' accounts without *Note `GRANT': grant, use *Note
`INSERT': insert. statements as follows to modify the grant tables
directly:

     shell> mysql --user=root mysql
     mysql> INSERT INTO user (Host,User,Password)
         ->     VALUES('localhost','custom',PASSWORD('obscure'));
     mysql> INSERT INTO user (Host,User,Password)
         ->     VALUES('host47.example.com','custom',PASSWORD('obscure'));
     mysql> INSERT INTO user (Host,User,Password)
         ->     VALUES('server.domain','custom',PASSWORD('obscure'));
     mysql> INSERT INTO db
         ->     (Host,Db,User,Select_priv,Insert_priv,
         ->     Update_priv,Delete_priv,Create_priv,Drop_priv)
         ->     VALUES('localhost','bankaccount','custom',
         ->     'Y','Y','Y','Y','Y','Y');
     mysql> INSERT INTO db
         ->     (Host,Db,User,Select_priv,Insert_priv,
         ->     Update_priv,Delete_priv,Create_priv,Drop_priv)
         ->     VALUES('host47.example.com','expenses','custom',
         ->     'Y','Y','Y','Y','Y','Y');
     mysql> INSERT INTO db
         ->     (Host,Db,User,Select_priv,Insert_priv,
         ->     Update_priv,Delete_priv,Create_priv,Drop_priv)
         ->     VALUES('server.domain','customer','custom',
         ->     'Y','Y','Y','Y','Y','Y');
     mysql> FLUSH PRIVILEGES;

The first three *Note `INSERT': insert. statements add `user' table
entries that allow the user `custom' to connect from the various hosts
with the given password, but grant no global privileges (all privileges
are set to the default value of `'N''). The next three *Note `INSERT':
insert. statements add `db' table entries that grant privileges to
`custom' for the `bankaccount', `expenses', and `customer' databases,
but only when accessed from the proper hosts. As usual when you modify
the grant tables directly, you must tell the server to reload them with
*Note `FLUSH PRIVILEGES': flush.  so that the privilege changes take
effect.

To create a user who has access from all machines in a given domain
(for example, `mydomain.com'), you can use the ``%'' wildcard character
in the host part of the account name:

     mysql> CREATE USER 'myname'@'%.mydomain.com' IDENTIFIED BY 'mypass';

To do the same thing by modifying the grant tables directly, do this:

     mysql> INSERT INTO user (Host,User,Password,...)
         ->     VALUES('%.mydomain.com','myname',PASSWORD('mypass'),...);
     mysql> FLUSH PRIVILEGES;


File: manual.info,  Node: removing-users,  Next: user-resources,  Prev: adding-users,  Up: user-account-management

5.5.3 Removing User Accounts
----------------------------

To remove an account, use the *Note `DROP USER': drop-user. statement,
which is described in *Note drop-user::.


File: manual.info,  Node: user-resources,  Next: passwords,  Prev: removing-users,  Up: user-account-management

5.5.4 Limiting Account Resources
--------------------------------

One means of limiting use of MySQL server resources is to set the
`max_user_connections' system variable to a non-zero value. However,
this limits only the number of simultaneous connections made using a
single account, and not what a client can do once connected. In
addition, this method is strictly global, and does not allow for
management of individual accounts. Both types of control are of
interest to many MySQL administrators, particularly those working for
Internet Service Providers.

In MySQL 6.0, you can limit the following server resources for
individual accounts:

   * The number of queries that an account can issue per hour

   * The number of updates that an account can issue per hour

   * The number of times an account can connect to the server per hour

   * The number of simultaneous connections to the server an account
     can have

Any statement that a client can issue counts against the query limit.
Only statements that modify databases or tables count against the
update limit.

An `account' in this context corresponds to a single row in the `user'
table. That is, connections are assessed against the `User' and `Host'
values in the `user' table row that applies to the connection. Suppose
that there is a row in the `user' table that has `User' and `Host'
values of `usera' and `%.example.com', to allow `usera' to connect from
any host in the `example.com' domain. In this case, the server applies
resource limits collectively to all connections by `usera' from any
host in the `example.com' domain because all such connections use the
same account.

Before MySQL 5.0.3, an `account' was assessed against the actual host
from which a user connects. This older method accounting may be
selected by starting the server with the `--old-style-user-limits'
option. In this case, if `usera' connects simultaneously from
`host1.example.com' and `host2.example.com', the server applies the
account resource limits separately to each connection. If `usera'
connects again from `host1.example.com', the server applies the limits
for that connection together with the existing connection from that
host.

The server limits account resources based on the resource-related
columns of the `user' table in the `mysql' database: `max_questions',
`max_updates', `max_connections', and `max_user_connections'. If your
`user' table does not have these columns, it must be upgraded; see
*Note mysql-upgrade::.

To set resource limits, use the *Note `GRANT': grant. statement and
provide a `WITH' clause that names each resource to be limited. For
example, to create a new account that can access the `customer'
database, but only in a limited fashion, issue these statements:

     mysql> CREATE USER 'francis'@'localhost' IDENTIFIED BY 'frank';
     mysql> GRANT ALL ON customer.* TO 'francis'@'localhost'
         ->     WITH MAX_QUERIES_PER_HOUR 20
         ->          MAX_UPDATES_PER_HOUR 10
         ->          MAX_CONNECTIONS_PER_HOUR 5
         ->          MAX_USER_CONNECTIONS 2;

The limit types need not all be named in the `WITH' clause, but those
named can be present in any order. The value for each per-hour limit
should be an integer representing a count per hour. If the *Note
`GRANT': grant. statement has no `WITH' clause, the limits are each set
to the default value of zero (that is, no limit). For
`MAX_USER_CONNECTIONS', the limit is an integer representing the
maximum number of simultaneous connections the account can make at any
one time. If the limit is set to the default value of zero, the
`max_user_connections' system variable determines the number of
simultaneous connections for the account.

To modify limits for an existing account, use a *Note `GRANT USAGE':
grant.  statement at the global level (`ON *.*'). The following
statement changes the query limit for `francis' to 100:

     mysql> GRANT USAGE ON *.* TO 'francis'@'localhost'
         ->     WITH MAX_QUERIES_PER_HOUR 100;

This statement leaves the account's existing privileges unchanged and
modifies only the limit values specified.

To remove an existing limit, set its value to zero. For example, to
remove the limit on how many times per hour `francis' can connect, use
this statement:

     mysql> GRANT USAGE ON *.* TO 'francis'@'localhost'
         ->     WITH MAX_CONNECTIONS_PER_HOUR 0;

Resource-use counting takes place when any account has a non-zero limit
placed on its use of any of the resources.

As the server runs, it counts the number of times each account uses
resources. If an account reaches its limit on number of connections
within the last hour, further connections for the account are rejected
until that hour is up. Similarly, if the account reaches its limit on
the number of queries or updates, further queries or updates are
rejected until the hour is up. In all such cases, an appropriate error
message is issued.

Resource counting is done per account, not per client. For example, if
your account has a query limit of 50, you cannot increase your limit to
100 by making two simultaneous client connections to the server.
Queries issued on both connections are counted together.

Queries for which results are served from the query cache do not count
against the `MAX_QUERIES_PER_HOUR' limit.

The current per-hour resource-use counts can be reset globally for all
accounts, or individually for a given account:

   * To reset the current counts to zero for all accounts, issue a
     *Note `FLUSH USER_RESOURCES': flush. statement. The counts also
     can be reset by reloading the grant tables (for example, with a
     *Note `FLUSH PRIVILEGES': flush. statement or a *Note `mysqladmin
     reload': mysqladmin. command).

   * The counts for an individual account can be set to zero by
     re-granting it any of its limits. To do this, use *Note `GRANT
     USAGE': grant.  as described earlier and specify a limit value
     equal to the value that the account currently has.

Counter resets do not affect the `MAX_USER_CONNECTIONS' limit.

All counts begin at zero when the server starts; counts are not carried
over through a restart.

For the `MAX_USER_CONNECTIONS' limit, an edge case can occur if the
account currently has open the maximum number of connections allowed to
it: A disconnect followed quickly by a connect can result in an error
(`ER_TOO_MANY_USER_CONNECTIONS' or `ER_USER_LIMIT_REACHED') if the
server has not fully processed the disconnect by the time the connect
occurs.  When the server finishes disconnect processing, another
connection will once more be allowed.


File: manual.info,  Node: passwords,  Next: password-security,  Prev: user-resources,  Up: user-account-management

5.5.5 Assigning Account Passwords
---------------------------------

To assign a password when you create a new account with *Note `CREATE
USER': create-user, include an `IDENTIFIED BY' clause:

     mysql> CREATE USER 'jeffrey'@'localhost' IDENTIFIED BY 'biscuit';

To assign or change a password for an existing account, one way is to
issue a *Note `SET PASSWORD': set-password. statement:

     mysql> SET PASSWORD FOR 'jeffrey'@'localhost' = PASSWORD('biscuit');

Only users such as `root' that have update access to the `mysql'
database can change the password for other users. If you are not
connected as an anonymous user, you can change your own password by
omitting the `FOR' clause:

     mysql> SET PASSWORD = PASSWORD('biscuit');

You can also use a *Note `GRANT USAGE': grant. statement at the global
level (`ON *.*') to assign a password to an account without affecting
the account's current privileges:

     mysql> GRANT USAGE ON *.* TO 'jeffrey'@'localhost' IDENTIFIED BY 'biscuit';

Passwords can be assigned from the command line by using the *Note
`mysqladmin': mysqladmin. command:

     shell> mysqladmin -u USER_NAME -h HOST_NAME password "NEWPWD"

The account for which this command resets the password is the one with
a `user' table row that matches USER_NAME in the `User' column and the
client host _from which you connect_ in the `Host' column.

Although it is generally preferable to assign passwords using one of
the preceding methods, you can also do so by modifying the `user' table
directly:

   * To establish a password when creating a new account, provide a
     value for the `Password' column:

          shell> mysql -u root mysql
          mysql> INSERT INTO user (Host,User,Password)
              -> VALUES('localhost','jeffrey',PASSWORD('biscuit'));
          mysql> FLUSH PRIVILEGES;

   * To change the password for an existing account, use *Note
     `UPDATE': update. to set the `Password' column value:

          shell> mysql -u root mysql
          mysql> UPDATE user SET Password = PASSWORD('bagel')
              -> WHERE Host = 'localhost' AND User = 'francis';
          mysql> FLUSH PRIVILEGES;

When you assign passwords using *Note `CREATE USER': create-user. or
*Note `GRANT': grant. with an `IDENTIFIED BY' clause or with the *Note
`mysqladmin password': mysqladmin. command, they take care of
encrypting the password for you.

When you assign an account a non-empty password using *Note `SET
PASSWORD': set-password, *Note `INSERT': insert, or *Note `UPDATE':
update, you must use the `PASSWORD()' function to encrypt the password.
`PASSWORD()' is necessary because the `user' table stores passwords in
encrypted form, not as plaintext. If you forget that fact, you are
likely to set passwords like this:

     shell> mysql -u root mysql
     mysql> INSERT INTO user (Host,User,Password)
         -> VALUES('localhost','jeffrey','biscuit');
     mysql> FLUSH PRIVILEGES;

The result is that the literal value `'biscuit'' is stored as the
password in the `user' table, not the encrypted value. When `jeffrey'
attempts to connect to the server using this password, the value is
encrypted and compared to the value stored in the `user' table.
However, the stored value is the literal string `'biscuit'', so the
comparison fails and the server rejects the connection:

     shell> mysql -u jeffrey -pbiscuit test
     Access denied

*Note*:

`PASSWORD()' encryption differs from Unix password encryption. See
*Note user-names::.


File: manual.info,  Node: password-security,  Next: secure-connections,  Prev: passwords,  Up: user-account-management

5.5.6 Password Security in MySQL
--------------------------------

* Menu:

* password-security-admin::      Administrator Guidelines for Password Security
* password-security-user::       End-User Guidelines for Password Security
* password-hashing::             Password Hashing in MySQL
* application-password-use::     Implications of Password Hashing Changes in MySQL 4.1 for Application Programs

Passwords occur in several contexts within MySQL. The following
sections provide guidelines that enable administrators and end users to
keep these passwords secure and avoid exposing them.  There is also a
discussion of how MySQL uses password hashing internally.


File: manual.info,  Node: password-security-admin,  Next: password-security-user,  Prev: password-security,  Up: password-security

5.5.6.1 Administrator Guidelines for Password Security
......................................................

Database administrators should use the following guidelines to keep
passwords secure.

MySQL stores passwords for user accounts in the `mysql.user' table.
Access to this table should never be granted to any non-administrative
accounts.

Passwords can appear as plain text in SQL statements such as *Note
`CREATE USER': create-user, *Note `GRANT': grant, and *Note `SET
PASSWORD': set-password. If these statements are logged by the MySQL
server, the passwords become available to anyone with access to the
logs. This applies to the general query log, the slow query log, and
the binary log (see *Note server-logs::). To guard against unwarranted
exposure to log files, they should be located in a directory that
restricts access to only the server and the database administrator. If
you log to tables in the `mysql' database, access to the tables should
never be granted to any non-administrative accounts.

Database backups that include tables or log files containing passwords
should be protected using a restricted access mode.


File: manual.info,  Node: password-security-user,  Next: password-hashing,  Prev: password-security-admin,  Up: password-security

5.5.6.2 End-User Guidelines for Password Security
.................................................

MySQL users should use the following guidelines to keep passwords
secure.

When you run a client program to connect to the MySQL server, it is
inadvisable to specify your password in a way that exposes it to
discovery by other users. The methods you can use to specify your
password when you run client programs are listed here, along with an
assessment of the risks of each method. In short, the safest methods
are to have the client program prompt for the password or to specify
the password in a properly protected option file.

   * Use a `-pYOUR_PASS' or `--password=YOUR_PASS' option on the
     command line. For example:

          shell> mysql -u francis -pfrank DB_NAME

     This is convenient _but insecure_, because your password becomes
     visible to system status programs such as `ps' that may be invoked
     by other users to display command lines. MySQL clients typically
     overwrite the command-line password argument with zeros during
     their initialization sequence. However, there is still a brief
     interval during which the value is visible.  Also, on some systems
     this overwriting strategy is ineffective and the password remains
     visible to `ps'. (SystemV Unix systems and perhaps others are
     subject to this problem.)

     If your operating environment is set up to display your current
     command in the title bar of your terminal window, the password
     remains visible as long as the command is running, even if the
     command has scrolled out of view in the window content area.

   * Use the `-p' or `--password' option on the command line with no
     password value specified.  In this case, the client program
     solicits the password interactively:

          shell> mysql -u francis -p DB_NAME
          Enter password: ********

     The ``*'' characters indicate where you enter your password. The
     password is not displayed as you enter it.

     It is more secure to enter your password this way than to specify
     it on the command line because it is not visible to other users.
     However, this method of entering a password is suitable only for
     programs that you run interactively. If you want to invoke a
     client from a script that runs non-interactively, there is no
     opportunity to enter the password from the keyboard. On some
     systems, you may even find that the first line of your script is
     read and interpreted (incorrectly) as your password.

   * Store your password in an option file. For example, on Unix you
     can list your password in the `[client]' section of the `.my.cnf'
     file in your home directory:

          [client]
          password=your_pass

     To keep the password safe, the file should not be accessible to
     anyone but yourself. To ensure this, set the file access mode to
     `400' or `600'.  For example:

          shell> chmod 600 .my.cnf

     *Note option-files::, discusses option files in more detail.

   * Store your password in the `MYSQL_PWD' environment variable. See
     *Note environment-variables::.

     This method of specifying your MySQL password must be considered
     _extremely insecure_ and should not be used. Some versions of `ps'
     include an option to display the environment of running processes.
     If you set `MYSQL_PWD', your password is exposed to any other user
     who runs `ps'. Even on systems without such a version of `ps', it
     is unwise to assume that there are no other methods by which users
     can examine process environments.

On Unix, the *Note `mysql': mysql. client writes a record of executed
statements to a history file (see *Note mysql::). By default, this file
is named `.mysql_history' and is created in your home directory.
Passwords can appear as plain text in SQL statements such as *Note
`CREATE USER': create-user, *Note `GRANT': grant, and *Note `SET
PASSWORD': set-password, so if you use these statements, they are
logged in the history file. To keep this file safe, use a restrictive
access mode, the same way as described earlier for the `.my.cnf' file.


File: manual.info,  Node: password-hashing,  Next: application-password-use,  Prev: password-security-user,  Up: password-security

5.5.6.3 Password Hashing in MySQL
.................................

MySQL user accounts are listed in the `user' table of the `mysql'
database. Each MySQL account is assigned a password, although what is
stored in the `Password' column of the `user' table is not the
plaintext version of the password, but a hash value computed from it.
Password hash values are computed by the `PASSWORD()' function.

MySQL uses passwords in two phases of client/server communication:

   * When a client attempts to connect to the server, there is an
     initial authentication step in which the client must present a
     password that has a hash value matching the hash value stored in
     the `user' table for the account that the client wants to use.

   * After the client connects, it can (if it has sufficient
     privileges) set or change the password hashes for accounts listed
     in the `user' table. The client can do this by using the
     `PASSWORD()' function to generate a password hash, or by using the
     *Note `GRANT': grant. or *Note `SET PASSWORD': set-password.
     statements.

In other words, the server _uses_ hash values during authentication
when a client first attempts to connect.  The server _generates_ hash
values if a connected client invokes the `PASSWORD()' function or uses a
*Note `GRANT': grant. or *Note `SET PASSWORD': set-password. statement
to set or change a password.

The password hashing mechanism was updated in MySQL 4.1 to provide
better security and to reduce the risk of passwords being intercepted.
However, this new mechanism is understood only by MySQL 4.1 (and newer)
servers and clients, which can result in some compatibility problems. A
4.1 or newer client can connect to a pre-4.1 server, because the client
understands both the old and new password hashing mechanisms. However,
a pre-4.1 client that attempts to connect to a 4.1 or newer server may
run into difficulties. For example, a 3.23 *Note `mysql': mysql.
client that attempts to connect to a 6.0 server may fail with the
following error message:

     shell> mysql -h localhost -u root
     Client does not support authentication protocol requested
     by server; consider upgrading MySQL client

Another common example of this phenomenon occurs for attempts to use
the older PHP `mysql' extension after upgrading to MySQL 4.1 or newer.
(See *Note apis-php-problems::.)

The following discussion describes the differences between the old and
new password mechanisms, and what you should do if you upgrade your
server but need to maintain backward compatibility with pre-4.1
clients. Additional information can be found in *Note old-client::.
This information is of particular importance to PHP programmers
migrating MySQL databases from version 4.0 or lower to version 4.1 or
higher.

*Note*:

This discussion contrasts 4.1 behavior with pre-4.1 behavior, but the
4.1 behavior described here actually begins with 4.1.1. MySQL 4.1.0 is
an `odd' release because it has a slightly different mechanism than
that implemented in 4.1.1 and up. Differences between 4.1.0 and more
recent versions are described further in MySQL 5.1 Reference Manual.

Prior to MySQL 4.1, password hashes computed by the `PASSWORD()'
function are 16 bytes long. Such hashes look like this:

     mysql> SELECT PASSWORD('mypass');
     +--------------------+
     | PASSWORD('mypass') |
     +--------------------+
     | 6f8c114b58f2ce9e   |
     +--------------------+

The `Password' column of the `user' table (in which these hashes are
stored) also is 16 bytes long before MySQL 4.1.

As of MySQL 4.1, the `PASSWORD()' function has been modified to produce
a longer 41-byte hash value:

     mysql> SELECT PASSWORD('mypass');
     +-------------------------------------------+
     | PASSWORD('mypass')                        |
     +-------------------------------------------+
     | *6C8989366EAF75BB670AD8EA7A7FC1176A95CEF4 |
     +-------------------------------------------+

Accordingly, the `Password' column in the `user' table also must be 41
bytes long to store these values:

   * If you perform a new installation of MySQL 6.0, the `Password'
     column is made 41 bytes long automatically.

   * Upgrading from MySQL 4.1 (4.1.1 or later in the 4.1 series) to
     MySQL 6.0 should not give rise to any issues in this regard
     because both versions use the same password hashing mechanism. If
     you wish to upgrade an older release of MySQL to version 6.0, you
     should upgrade to version 4.1 first, then upgrade the 4.1
     installation to 6.0.

A widened `Password' column can store password hashes in both the old
and new formats. The format of any given password hash value can be
determined two ways:

   * The obvious difference is the length (16 bytes versus 41 bytes).

   * A second difference is that password hashes in the new format
     always begin with a ``*'' character, whereas passwords in the old
     format never do.

The longer password hash format has better cryptographic properties,
and client authentication based on long hashes is more secure than that
based on the older short hashes.

The differences between short and long password hashes are relevant
both for how the server uses passwords during authentication and for
how it generates password hashes for connected clients that perform
password-changing operations.

The way in which the server uses password hashes during authentication
is affected by the width of the `Password' column:

   * If the column is short, only short-hash authentication is used.

   * If the column is long, it can hold either short or long hashes,
     and the server can use either format:

        * Pre-4.1 clients can connect, although because they know only
          about the old hashing mechanism, they can authenticate only
          using accounts that have short hashes.

        * 4.1 and later clients can authenticate using accounts that
          have short or long hashes.

Even for short-hash accounts, the authentication process is actually a
bit more secure for 4.1 and later clients than for older clients. In
terms of security, the gradient from least to most secure is:

   * Pre-4.1 client authenticating with short password hash

   * 4.1 or later client authenticating with short password hash

   * 4.1 or later client authenticating with long password hash

The way in which the server generates password hashes for connected
clients is affected by the width of the `Password' column and by the
`--old-passwords' option. A 4.1 or later server generates long hashes
only if certain conditions are met: The `Password' column must be wide
enough to hold long values and the `--old-passwords' option must not be
given. These conditions apply as follows:

   * The `Password' column must be wide enough to hold long hashes (41
     bytes). If the column has not been updated and still has the
     pre-4.1 width of 16 bytes, the server notices that long hashes
     cannot fit into it and generates only short hashes when a client
     performs password-changing operations using `PASSWORD()', *Note
     `GRANT': grant, or *Note `SET PASSWORD': set-password. This is the
     behavior that occurs if you have upgraded to 4.1 but have not yet
     run the *Note `mysql_upgrade': mysql-upgrade. program to widen the
     `Password' column.

   * If the `Password' column is wide, it can store either short or
     long password hashes. In this case, `PASSWORD()', *Note `GRANT':
     grant, and *Note `SET PASSWORD': set-password. generate long
     hashes unless the server was started with the `--old-passwords'
     option. That option forces the server to generate short password
     hashes instead.

The purpose of the `--old-passwords' option is to enable you to
maintain backward compatibility with pre-4.1 clients under
circumstances where the server would otherwise generate long password
hashes. The option doesn't affect authentication (4.1 and later clients
can still use accounts that have long password hashes), but it does
prevent creation of a long password hash in the `user' table as the
result of a password-changing operation. Were that to occur, the
account no longer could be used by pre-4.1 clients. Without the
`--old-passwords' option, the following undesirable scenario is
possible:

   * An old client connects to an account that has a short password
     hash.

   * The client changes its own password. Without `--old-passwords',
     this results in the account having a long password hash.

   * The next time the old client attempts to connect to the account,
     it cannot, because the account has a long password hash that
     requires the new hashing mechanism during authentication. (Once an
     account has a long password hash in the user table, only 4.1 and
     later clients can authenticate for it, because pre-4.1 clients do
     not understand long hashes.)

This scenario illustrates that, if you must support older pre-4.1
clients, it is dangerous to run a 4.1 or newer server without using the
`--old-passwords' option. By running the server with `--old-passwords',
password-changing operations do not generate long password hashes and
thus do not cause accounts to become inaccessible to older clients.
(Those clients cannot inadvertently lock themselves out by changing
their password and ending up with a long password hash.)

The downside of the `--old-passwords' option is that any passwords you
create or change use short hashes, even for 4.1 clients. Thus, you lose
the additional security provided by long password hashes. If you want
to create an account that has a long hash (for example, for use by 4.1
clients), you must do so while running the server without
`--old-passwords'.

MySQL Enterprise

Subscribers to the MySQL Enterprise Monitor are automatically alerted
whenever a server is running with the `--old-passwords' option. For
more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The following scenarios are possible for running a 4.1 or later server:

*Scenario 1:* Short `Password' column in user table:

   * Only short hashes can be stored in the `Password' column.

   * The server uses only short hashes during client authentication.

   * For connected clients, password hash-generating operations
     involving `PASSWORD()', *Note `GRANT': grant, or *Note `SET
     PASSWORD': set-password. use short hashes exclusively. Any change
     to an account's password results in that account having a short
     password hash.

   * The `--old-passwords' option can be used but is superfluous
     because with a short `Password' column, the server generates only
     short password hashes anyway.

*Scenario 2:* Long `Password' column; server not started with
`--old-passwords' option:

   * Short or long hashes can be stored in the `Password' column.

   * 4.1 and later clients can authenticate using accounts that have
     short or long hashes.

   * Pre-4.1 clients can authenticate only using accounts that have
     short hashes.

   * For connected clients, password hash-generating operations
     involving `PASSWORD()', *Note `GRANT': grant, or *Note `SET
     PASSWORD': set-password. use long hashes exclusively. A change to
     an account's password results in that account having a long
     password hash.

As indicated earlier, a danger in this scenario is that it is possible
for accounts that have a short password hash to become inaccessible to
pre-4.1 clients. A change to such an account's password made via *Note
`GRANT': grant, `PASSWORD()', or *Note `SET PASSWORD': set-password.
results in the account being given a long password hash. From that
point on, no pre-4.1 client can authenticate to that account until the
client upgrades to 4.1.

To deal with this problem, you can change a password in a special way.
For example, normally you use *Note `SET PASSWORD': set-password. as
follows to change an account password:

     SET PASSWORD FOR 'SOME_USER'@'SOME_HOST' = PASSWORD('mypass');

To change the password but create a short hash, use the
`OLD_PASSWORD()' function instead:

     SET PASSWORD FOR 'SOME_USER'@'SOME_HOST' = OLD_PASSWORD('mypass');

`OLD_PASSWORD()' is useful for situations in which you explicitly want
to generate a short hash.

*Scenario 3:* Long `Password' column; 4.1 or newer server started with
`--old-passwords' option:

   * Short or long hashes can be stored in the `Password' column.

   * 4.1 and later clients can authenticate for accounts that have
     short or long hashes (but note that it is possible to create long
     hashes only when the server is started without `--old-passwords').

   * Pre-4.1 clients can authenticate only for accounts that have short
     hashes.

   * For connected clients, password hash-generating operations
     involving `PASSWORD()', *Note `GRANT': grant, or *Note `SET
     PASSWORD': set-password. use short hashes exclusively. Any change
     to an account's password results in that account having a short
     password hash.

In this scenario, you cannot create accounts that have long password
hashes, because the `--old-passwords' option prevents generation of
long hashes. Also, if you create an account with a long hash before
using the `--old-passwords' option, changing the account's password
while `--old-passwords' is in effect results in the account being given
a short password, causing it to lose the security benefits of a longer
hash.

The disadvantages for these scenarios may be summarized as follows:

In scenario 1, you cannot take advantage of longer hashes that provide
more secure authentication.

In scenario 2, accounts with short hashes become inaccessible to
pre-4.1 clients if you change their passwords without explicitly using
`OLD_PASSWORD()'.

In scenario 3, `--old-passwords' prevents accounts with short hashes
from becoming inaccessible, but password-changing operations cause
accounts with long hashes to revert to short hashes, and you cannot
change them back to long hashes while `--old-passwords' is in effect.


File: manual.info,  Node: application-password-use,  Prev: password-hashing,  Up: password-security

5.5.6.4 Implications of Password Hashing Changes in MySQL 4.1 for Application Programs
......................................................................................

An upgrade to MySQL version 4.1 or later can cause compatibility issues
for applications that use `PASSWORD()' to generate passwords for their
own purposes. Applications really should not do this, because
`PASSWORD()' should be used only to manage passwords for MySQL
accounts. But some applications use `PASSWORD()' for their own purposes
anyway.

If you upgrade to 4.1 or later from a pre-4.1 version of MySQL and run
the server under conditions where it generates long password hashes, an
application using `PASSWORD()' for its own passwords breaks. The
recommended course of action in such cases is to modify the application
to use another function, such as `SHA1()' or `MD5()', to produce hashed
values.  If that is not possible, you can use the `OLD_PASSWORD()'
function, which is provided for generate short hashes in the old
format. However, you should note that `OLD_PASSWORD()' may one day no
longer be supported.

If the server is running under circumstances where it generates short
hashes, `OLD_PASSWORD()' is available but is equivalent to `PASSWORD()'.

PHP programmers migrating their MySQL databases from version 4.0 or
lower to version 4.1 or higher should see *Note apis-php::.


File: manual.info,  Node: secure-connections,  Next: windows-and-ssh,  Prev: password-security,  Up: user-account-management

5.5.7 Using SSL for Secure Connections
--------------------------------------

* Menu:

* secure-basics::                Basic SSL Concepts
* secure-using-ssl::             Using SSL Connections
* ssl-options::                  SSL Command Options
* secure-create-certs::          Setting Up SSL Certificates for MySQL

MySQL supports secure (encrypted) connections between MySQL clients and
the server using the Secure Sockets Layer (SSL) protocol. This section
discusses how to use SSL connections. For information on how to require
users to use SSL connections, see the discussion of the `REQUIRE'
clause of the *Note `GRANT': grant. statement in *Note grant::.

The standard configuration of MySQL is intended to be as fast as
possible, so encrypted connections are not used by default. Doing so
would make the client/server protocol much slower. Encrypting data is a
CPU-intensive operation that requires the computer to do additional
work and can delay other MySQL tasks. For applications that require the
security provided by encrypted connections, the extra computation is
warranted.

MySQL allows encryption to be enabled on a per-connection basis.  You
can choose a normal unencrypted connection or a secure encrypted SSL
connection according the requirements of individual applications.

Secure connections are based on the OpenSSL API and are available
through the MySQL C API. Replication uses the C API, so secure
connections can be used between master and slave servers.

Another way to connect securely is from within an SSH connection to the
MySQL server host. For an example, see *Note windows-and-ssh::.


File: manual.info,  Node: secure-basics,  Next: secure-using-ssl,  Prev: secure-connections,  Up: secure-connections

5.5.7.1 Basic SSL Concepts
..........................

To understand how MySQL uses SSL, it is necessary to explain some basic
SSL and X509 concepts. People who are familiar with these can skip this
part of the discussion.

By default, MySQL uses unencrypted connections between the client and
the server. This means that someone with access to the network could
watch all your traffic and look at the data being sent or received.
They could even change the data while it is in transit between client
and server. To improve security a little, you can compress
client/server traffic by using the `--compress' option when invoking
client programs. However, this does not foil a determined attacker.

When you need to move information over a network in a secure fashion,
an unencrypted connection is unacceptable. Encryption is the way to
make any kind of data unreadable. In fact, today's practice requires
many additional security elements from encryption algorithms. They
should resist many kind of known attacks such as changing the order of
encrypted messages or replaying data twice.

SSL is a protocol that uses different encryption algorithms to ensure
that data received over a public network can be trusted.  It has
mechanisms to detect any data change, loss, or replay.  SSL also
incorporates algorithms that provide identity verification using the
X509 standard.

X509 makes it possible to identify someone on the Internet. It is most
commonly used in e-commerce applications. In basic terms, there should
be some company called a `Certificate Authority' (or CA) that assigns
electronic certificates to anyone who needs them. Certificates rely on
asymmetric encryption algorithms that have two encryption keys (a public
key and a secret key). A certificate owner can show the certificate to
another party as proof of identity. A certificate consists of its
owner's public key. Any data encrypted with this public key can be
decrypted only using the corresponding secret key, which is held by the
owner of the certificate.

If you need more information about SSL, X509, or encryption, use your
favorite Internet search engine to search for the keywords in which you
are interested.


File: manual.info,  Node: secure-using-ssl,  Next: ssl-options,  Prev: secure-basics,  Up: secure-connections

5.5.7.2 Using SSL Connections
.............................

To use SSL connections between the MySQL server and client programs,
your system must support either OpenSSL or yaSSL and your version of
MySQL must be built with SSL support.

To make it easier to use secure connections, MySQL is bundled with
yaSSL. (MySQL and yaSSL employ the same licensing model, whereas
OpenSSL uses an Apache-style license.) yaSSL support initially was
available only for a few platforms, but now it is available on all
MySQL platforms supported by Sun Microsystems, Inc.

To get secure connections to work with MySQL and SSL, you must do the
following:

  1. If you are not using a binary (precompiled) version of MySQL that
     has been built with SSL support, and you are going to use OpenSSL
     rather than the bundled yaSSL library, install OpenSSL if it has
     not already been installed. We have tested MySQL with OpenSSL
     0.9.6. To obtain OpenSSL, visit `http://www.openssl.org'.

  2. If you are not using a binary (precompiled) version of MySQL that
     has been built with SSL support, configure a MySQL source
     distribution to use SSL. When you configure MySQL, invoke the
     `configure' script like this:

          shell> ./configure --with-ssl

     That configures the distribution to use the bundled yaSSL library.
     To use OpenSSL instead, specify the `--with-ssl' option with the
     path to the directory where the OpenSSL header files and libraries
     are located:

          shell> ./configure --with-ssl=PATH

     Note that yaSSL support on Unix platforms requires that either
     `/dev/urandom' or `/dev/random' be available to retrieve true
     random numbers. For additional information (especially regarding
     yaSSL on Solaris versions prior to 2.8 and HP-UX), see Bug#13164
     (http://bugs.mysql.com/13164).

  3. Make sure that the `user' in the `mysql' database includes the
     SSL-related columns (beginning with `ssl_' and `x509_'). If your
     `user' table does not have these columns, it must be upgraded; see
     *Note mysql-upgrade::.

  4. To check whether a server binary is compiled with SSL support,
     invoke it with the `--ssl' option. An error will occur if the
     server does not support SSL:

          shell> mysqld --ssl --help
          060525 14:18:52 [ERROR] mysqld: unknown option '--ssl'

     To check whether a running *Note `mysqld': mysqld. server supports
     SSL, examine the value of the `have_ssl' system variable:

          mysql> SHOW VARIABLES LIKE 'have_ssl';
          +---------------+-------+
          | Variable_name | Value |
          +---------------+-------+
          | have_ssl      | YES   |
          +---------------+-------+

     If the value is `YES', the server supports SSL connections. If the
     value is `DISABLED', the server supports SSL connections but was
     not started with the appropriate `--ssl-XXX' options (described
     later in this section).

To enable SSL connections, the proper SSL-related options must be used
(see *Note ssl-options::).

To start the MySQL server so that it allows clients to connect via SSL,
use the options that identify the key and certificate files the server
needs when establishing a secure connection:

     shell> mysqld --ssl-ca=CACERT.PEM \
            --ssl-cert=SERVER-CERT.PEM \
            --ssl-key=SERVER-KEY.PEM

   * `--ssl-ca' identifies the Certificate Authority (CA) certificate.

   * `--ssl-cert' identifies the server public key. This can be sent to
     the client and authenticated against the CA certificate that it
     has.

   * `--ssl-key' identifies the server private key.

To establish a secure connection to a MySQL server with SSL support,
the options that a client must specify depend on the SSL requirements
of the user account that the client uses. (See the discussion of the
`REQUIRE' clause in *Note grant::.)

If the account has no special SSL requirements or was created using a
*Note `GRANT': grant. statement that includes the `REQUIRE SSL' option,
a client can connect securely by using just the `--ssl-ca' option:

     shell> mysql --ssl-ca=CACERT.PEM

To require that a client certificate also be specified, create the
account using the `REQUIRE X509' option.  Then the client must also
specify the proper client key and certificate files or the server will
reject the connection:

     shell> mysql --ssl-ca=CACERT.PEM \
            --ssl-cert=CLIENT-CERT.PEM \
            --ssl-key=CLIENT-KEY.PEM

In other words, the options are similar to those used for the server.
Note that the Certificate Authority certificate has to be the same.

A client can determine whether the current connection with the server
uses SSL by checking the value of the `Ssl_cipher' status variable.
The value of `Ssl_cipher' is non-empty if SSL is used, and empty
otherwise. For example:

     mysql> SHOW STATUS LIKE 'Ssl_cipher';
     +---------------+--------------------+
     | Variable_name | Value              |
     +---------------+--------------------+
     | Ssl_cipher    | DHE-RSA-AES256-SHA |
     +---------------+--------------------+

For the *Note `mysql': mysql. client, you can use the `STATUS' or `\s'
command and check the `SSL' line:

     mysql> \s
     ...
     SSL:                    Not in use
     ...

Or:

     mysql> \s
     ...
     SSL:                    Cipher in use is DHE-RSA-AES256-SHA
     ...

To establish a secure connection from within an application program,
use the *Note `mysql_ssl_set()': mysql-ssl-set.  C API function to set
the appropriate certificate options before calling *Note
`mysql_real_connect()': mysql-real-connect.  See *Note mysql-ssl-set::.
After the connection is established, you can use *Note
`mysql_get_ssl_cipher()': mysql-get-ssl-cipher. to determine whether
SSL is in use. A non-`NULL' return value indicates a secure connection
and names the SSL cipher used for encryption. A `NULL' return value
indicates that SSL is not being used. See *Note mysql-get-ssl-cipher::.


File: manual.info,  Node: ssl-options,  Next: secure-create-certs,  Prev: secure-using-ssl,  Up: secure-connections

5.5.7.3 SSL Command Options
...........................

The following list describes options that are used for specifying the
use of SSL, certificate files, and key files.  They can be given on the
command line or in an option file.  These options are not available
unless MySQL has been built with SSL support. See *Note
secure-using-ssl::.

*`mysqld' SSL Option/Variable Summary*

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
have_openssl                                                                                                                                        Yes                                                                                                                   Global                                                     No
have_ssl                                                                                                                                            Yes                                                                                                                   Global                                                     No
skip-ssl                      Yes                                                        Yes                                                                                                                                                                                                                                         
ssl                           Yes                                                        Yes                                                                                                                                                                                                                                         
ssl-ca                        Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_ca                                                                                                                                Yes                                                                                                                   Global                                                     No
ssl-capath                    Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_capath                                                                                                                            Yes                                                                                                                   Global                                                     No
ssl-cert                      Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_cert                                                                                                                              Yes                                                                                                                   Global                                                     No
ssl-cipher                    Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_cipher                                                                                                                            Yes                                                                                                                   Global                                                     No
ssl-key                       Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_key                                                                                                                               Yes                                                                                                                   Global                                                     No
ssl-verify-server-cert        Yes                                                        Yes                                                                                                                                                                                                                                         

   *  `--ssl'

     For the server, this option specifies that the server allows SSL
     connections. For a client program, it allows the client to connect
     to the server using SSL. This option is not sufficient in itself
     to cause an SSL connection to be used.  You must also specify the
     `--ssl-ca' option, and possibly the `--ssl-cert' and `--ssl-key'
     options.

     This option is more often used in its opposite form to override
     any other SSL options and indicate that SSL should _not_ be used.
     To do this, specify the option as `--skip-ssl' or `--ssl=0'.

     Note that use of `--ssl' does not _require_ an SSL connection. For
     example, if the server or client is compiled without SSL support,
     a normal unencrypted connection is used.

     The secure way to require use of an SSL connection is to create an
     account on the server that includes a `REQUIRE SSL' clause in the
     *Note `GRANT': grant. statement. Then use that account to connect
     to the server, where both the server and the client have SSL
     support enabled.

     The `REQUIRE' clause allows other SSL-related restrictions as
     well. The description of `REQUIRE' in *Note grant::, provides
     additional detail about which SSL command options may or must be
     specified by clients that connect using accounts that are created
     using the various `REQUIRE' options.

   *  `--ssl-ca=FILE_NAME'

     The path to a file that contains a list of trusted SSL CAs.

   *  `--ssl-capath=DIRECTORY_NAME'

     The path to a directory that contains trusted SSL CA certificates
     in PEM format.

   *  `--ssl-cert=FILE_NAME'

     The name of the SSL certificate file to use for establishing a
     secure connection.

   *  `--ssl-cipher=CIPHER_LIST'

     A list of allowable ciphers to use for SSL encryption. For
     greatest portability, CIPHER_LIST should be a list of one or more
     cipher names, separated by colons. Examples:

          --ssl-cipher=AES128-SHA
          --ssl-cipher=DHE-RSA-AES256-SHA:AES128-SHA

     This format is understood both by OpenSSL and yaSSL. OpenSSL
     supports a more flexible syntax for specifying ciphers, as
     described in the OpenSSL documentation at
     `http://www.openssl.org/docs/apps/ciphers.html'.  However, this
     extended syntax will fail if used with a MySQL installation
     compiled against yaSSL.

     If no cipher in the list is supported, SSL connections will not
     work.

   *  `--ssl-key=FILE_NAME'

     The name of the SSL key file to use for establishing a secure
     connection.

   *  `--ssl-verify-server-cert'

     This option is available for client programs only, not the server.
     It causes the server's Common Name value in the certificate that
     the server sends to the client to be verified against the host
     name that the client uses for connecting to the server, and the
     connection is rejected if there is a mismatch. This feature can be
     used to prevent man-in-the-middle attacks. Verification is
     disabled by default.

If you use SSL when establishing a client connection, you can tell the
client not to authenticate the server certificate by specifying neither
`--ssl-ca' nor `--ssl-capath'. The server still verifies the client
according to any applicable requirements established via *Note `GRANT':
grant. statements for the client, and it still uses any
`--ssl-ca'/`--ssl-capath' values that were passed to server at startup
time.


File: manual.info,  Node: secure-create-certs,  Prev: ssl-options,  Up: secure-connections

5.5.7.4 Setting Up SSL Certificates for MySQL
.............................................

This section demonstrates how to set up SSL certificate and key files
for use by MySQL servers and clients. The first example shows a
simplified procedure such as you might use from the command line. The
second shows a script that contains more detail. The first two examples
are intended for use on Unix and both use the `openssl' command that is
part of OpenSSL. The third example describes how to set up SSL files on
Windows.

Following the third example, instructions are given for using the files
to test SSL connections. You can also use the files as described in
*Note secure-using-ssl::.

*Example 1: Creating SSL files from the command line on Unix*

The following example shows a set of commands to create MySQL server
and client certificate and key files. You will need to respond to
several prompts by the `openssl' commands. For testing, you can press
Enter to all prompts. For production use, you should provide non-empty
responses.

     # Create clean environment
     shell> rm -rf newcerts
     shell> mkdir newcerts && cd newcerts

     # Create CA certificate
     shell> openssl genrsa 2048 > ca-key.pem
     shell> openssl req -new -x509 -nodes -days 1000 \
              -key ca-key.pem > ca-cert.pem

     # Create server certificate
     shell> openssl req -newkey rsa:2048 -days 1000 \
              -nodes -keyout server-key.pem > server-req.pem
     shell> openssl x509 -req -in server-req.pem -days 1000 \
              -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 > server-cert.pem

     # Create client certificate
     shell> openssl req -newkey rsa:2048 -days 1000 \
              -nodes -keyout client-key.pem > client-req.pem
     shell> openssl x509 -req -in client-req.pem -days 1000 \
              -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 > client-cert.pem

*Example 2: Creating SSL files using a script on Unix*

Here is an example script that shows how to set up SSL certificates for
MySQL:

     DIR=`pwd`/openssl
     PRIV=$DIR/private

     mkdir $DIR $PRIV $DIR/newcerts
     cp /usr/share/ssl/openssl.cnf $DIR
     replace ./demoCA $DIR -- $DIR/openssl.cnf

     # Create necessary files: $database, $serial and $new_certs_dir
     # directory (optional)

     touch $DIR/index.txt
     echo "01" > $DIR/serial

     #
     # Generation of Certificate Authority(CA)
     #

     openssl req -new -x509 -keyout $PRIV/cakey.pem -out $DIR/cacert.pem \
         -days 3600 -config $DIR/openssl.cnf

     # Sample output:
     # Using configuration from /home/monty/openssl/openssl.cnf
     # Generating a 1024 bit RSA private key
     # ................++++++
     # .........++++++
     # writing new private key to '/home/monty/openssl/private/cakey.pem'
     # Enter PEM pass phrase:
     # Verifying password - Enter PEM pass phrase:
     # -----
     # You are about to be asked to enter information that will be
     # incorporated into your certificate request.
     # What you are about to enter is what is called a Distinguished Name
     # or a DN.
     # There are quite a few fields but you can leave some blank
     # For some fields there will be a default value,
     # If you enter '.', the field will be left blank.
     # -----
     # Country Name (2 letter code) [AU]:FI
     # State or Province Name (full name) [Some-State]:.
     # Locality Name (eg, city) []:
     # Organization Name (eg, company) [Internet Widgits Pty Ltd]:MySQL AB
     # Organizational Unit Name (eg, section) []:
     # Common Name (eg, YOUR name) []:MySQL admin
     # Email Address []:

     #
     # Create server request and key
     #
     openssl req -new -keyout $DIR/server-key.pem -out \
         $DIR/server-req.pem -days 3600 -config $DIR/openssl.cnf

     # Sample output:
     # Using configuration from /home/monty/openssl/openssl.cnf
     # Generating a 1024 bit RSA private key
     # ..++++++
     # ..........++++++
     # writing new private key to '/home/monty/openssl/server-key.pem'
     # Enter PEM pass phrase:
     # Verifying password - Enter PEM pass phrase:
     # -----
     # You are about to be asked to enter information that will be
     # incorporated into your certificate request.
     # What you are about to enter is what is called a Distinguished Name
     # or a DN.
     # There are quite a few fields but you can leave some blank
     # For some fields there will be a default value,
     # If you enter '.', the field will be left blank.
     # -----
     # Country Name (2 letter code) [AU]:FI
     # State or Province Name (full name) [Some-State]:.
     # Locality Name (eg, city) []:
     # Organization Name (eg, company) [Internet Widgits Pty Ltd]:MySQL AB
     # Organizational Unit Name (eg, section) []:
     # Common Name (eg, YOUR name) []:MySQL server
     # Email Address []:
     #
     # Please enter the following 'extra' attributes
     # to be sent with your certificate request
     # A challenge password []:
     # An optional company name []:

     #
     # Remove the passphrase from the key
     #
     openssl rsa -in $DIR/server-key.pem -out $DIR/server-key.pem

     #
     # Sign server cert
     #
     openssl ca  -policy policy_anything -out $DIR/server-cert.pem \
         -config $DIR/openssl.cnf -infiles $DIR/server-req.pem

     # Sample output:
     # Using configuration from /home/monty/openssl/openssl.cnf
     # Enter PEM pass phrase:
     # Check that the request matches the signature
     # Signature ok
     # The Subjects Distinguished Name is as follows
     # countryName           :PRINTABLE:'FI'
     # organizationName      :PRINTABLE:'MySQL AB'
     # commonName            :PRINTABLE:'MySQL admin'
     # Certificate is to be certified until Sep 13 14:22:46 2003 GMT
     # (365 days)
     # Sign the certificate? [y/n]:y
     #
     #
     # 1 out of 1 certificate requests certified, commit? [y/n]y
     # Write out database with 1 new entries
     # Data Base Updated

     #
     # Create client request and key
     #
     openssl req -new -keyout $DIR/client-key.pem -out \
         $DIR/client-req.pem -days 3600 -config $DIR/openssl.cnf

     # Sample output:
     # Using configuration from /home/monty/openssl/openssl.cnf
     # Generating a 1024 bit RSA private key
     # .....................................++++++
     # .............................................++++++
     # writing new private key to '/home/monty/openssl/client-key.pem'
     # Enter PEM pass phrase:
     # Verifying password - Enter PEM pass phrase:
     # -----
     # You are about to be asked to enter information that will be
     # incorporated into your certificate request.
     # What you are about to enter is what is called a Distinguished Name
     # or a DN.
     # There are quite a few fields but you can leave some blank
     # For some fields there will be a default value,
     # If you enter '.', the field will be left blank.
     # -----
     # Country Name (2 letter code) [AU]:FI
     # State or Province Name (full name) [Some-State]:.
     # Locality Name (eg, city) []:
     # Organization Name (eg, company) [Internet Widgits Pty Ltd]:MySQL AB
     # Organizational Unit Name (eg, section) []:
     # Common Name (eg, YOUR name) []:MySQL user
     # Email Address []:
     #
     # Please enter the following 'extra' attributes
     # to be sent with your certificate request
     # A challenge password []:
     # An optional company name []:

     #
     # Remove the passphrase from the key
     #
     openssl rsa -in $DIR/client-key.pem -out $DIR/client-key.pem

     #
     # Sign client cert
     #

     openssl ca  -policy policy_anything -out $DIR/client-cert.pem \
         -config $DIR/openssl.cnf -infiles $DIR/client-req.pem

     # Sample output:
     # Using configuration from /home/monty/openssl/openssl.cnf
     # Enter PEM pass phrase:
     # Check that the request matches the signature
     # Signature ok
     # The Subjects Distinguished Name is as follows
     # countryName           :PRINTABLE:'FI'
     # organizationName      :PRINTABLE:'MySQL AB'
     # commonName            :PRINTABLE:'MySQL user'
     # Certificate is to be certified until Sep 13 16:45:17 2003 GMT
     # (365 days)
     # Sign the certificate? [y/n]:y
     #
     #
     # 1 out of 1 certificate requests certified, commit? [y/n]y
     # Write out database with 1 new entries
     # Data Base Updated

     #
     # Create a my.cnf file that you can use to test the certificates
     #

     cnf=""
     cnf="$cnf [client]"
     cnf="$cnf ssl-ca=$DIR/cacert.pem"
     cnf="$cnf ssl-cert=$DIR/client-cert.pem"
     cnf="$cnf ssl-key=$DIR/client-key.pem"
     cnf="$cnf [mysqld]"
     cnf="$cnf ssl-ca=$DIR/cacert.pem"
     cnf="$cnf ssl-cert=$DIR/server-cert.pem"
     cnf="$cnf ssl-key=$DIR/server-key.pem"
     echo $cnf | replace " " '
     ' > $DIR/my.cnf

*Example 3: Creating SSL files on Windows*

Download OpenSSL for Windows. An overview of available packages can be
seen here: `http://www.slproweb.com/products/Win32OpenSSL.html'

Choose of the following packages, depending on your architecture
(32-bit or 64-bit):

   * Win32 OpenSSL v0.9.8j Light, available at:
     `http://www.slproweb.com/download/Win32OpenSSL_Light-0_9_8j.exe'

   * Win64 OpenSSL v0.9.8j Light, available at:
     `http://www.slproweb.com/download/Win64OpenSSL_Light-0_9_8j.exe'

if a message occurs during setup indicating `'...critical component is
missing: Microsoft Visual C++ 2008 Redistributables'', cancel the setup
and download one of the following packages as well, again depending on
your architecture (32-bit or 64-bit):

   * Visual C++ 2008 Redistributables (x86), available at:
     `http://www.microsoft.com/downloads/details.aspx?familyid=9B2DA534-3E03-4391-8A4D-074B9F2BC1BF"isplaylang=en'

   * Visual C++ 2008 Redistributables (x64), available at:
     `http://www.microsoft.com/downloads/details.aspx?familyid=bd2a6171-e2d6-4230-b809-9a8d7548c1b6"isplaylang=en'

After installing the additional package, restart the OpenSSL setup.

During installation, leave the default `C:\OpenSSL' as the install
path, and also leave the default option `'Copy OpenSSL DLL files to the
Windows system directory'' selected.

When the installation has finished, add `C:\OpenSSL\bin' to the Windows
System Path variable of your server:

   * On the Windows desktop, right-click on the `My Computer' icon, and
     select `Properties'.

   * Next select the `Advanced' tab from the `System Properties' menu
     that appears, and click the `Environment Variables' button.

   * Under `System Variables', select `Path', and then click the `Edit'
     button. The `Edit System Variable' dialogue should appear.

   * Add `';C:\OpenSSL\bin'' to the end (notice the semicolon).

   * Press OK 3 times.

   * Check that OpenSSL was correctly integrated into the Path variable
     by opening a new command console (`Start>Run>cmd.exe') and
     verifying that OpenSSL is available:

          Microsoft Windows [Version ...]
          Copyright (c) 2006 Microsoft Corporation. All rights reserved.

          C:\Windows\system32>cd \

          C:\>openssl
          OpenSSL> exit <<< If you see the OpenSSL prompt, installation was successful.

          C:\>

Depending on your version of Windows, the preceding instructions might
be slightly different.

After OpenSSL has been installed, use the instructions from Example 1
(shown earlier in this section), with the following changes:

   * Change the follow Unix commands:

          # Create clean environment
          shell> rm -rf newcerts
          shell> mkdir newcerts && cd newcerts

     On Windows, use these commands instead:

          # Create clean environment
          shell> md c:\newcerts
          shell> cd c:\newcerts

   * When a `'\'' character is shown at the end of a command line, this
     `'\'' character must be removed and the command lines entered all
     on a single line.

   * For references to `my.cnf' option files, substitute `my.ini'
     instead.

*Testing SSL connections*

To test SSL connections, start the server as follows, where `$DIR' is
the path name to the directory where the sample `my.cnf' option file is
located:

     shell> mysqld --defaults-file=$DIR/my.cnf &

Then invoke a client program using the same option file:

     shell> mysql --defaults-file=$DIR/my.cnf

If you have a MySQL source distribution, you can also test your setup
by modifying the preceding `my.cnf' file to refer to the demonstration
certificate and key files in the `mysql-test/std_data' directory of the
distribution.


File: manual.info,  Node: windows-and-ssh,  Next: account-activity-auditing,  Prev: secure-connections,  Up: user-account-management

5.5.8 Connecting to MySQL Remotely from Windows with SSH
--------------------------------------------------------

This section describes how to get a secure connection to a remote MySQL
server with SSH. The information was provided by David Carlson
<dcarlson@mplcomm.com>.

  1. Install an SSH client on your Windows machine. As a user, the best
     non-free one I have found is from `SecureCRT' from
     `http://www.vandyke.com/'. Another option is `f-secure' from
     `http://www.f-secure.com/'. You can also find some free ones on
     `Google' at
     `http://directory.google.com/Top/Computers/Internet/Protocols/SSH/Clients/Windows/'.

  2. Start your Windows SSH client. Set `Host_Name =
     YOURMYSQLSERVER_URL_OR_IP'.  Set `userid=YOUR_USERID' to log in to
     your server. This `userid' value might not be the same as the user
     name of your MySQL account.

  3. Set up port forwarding. Either do a remote forward (Set
     `local_port: 3306', `remote_host: YOURMYSQLSERVERNAME_OR_IP',
     `remote_port: 3306' ) or a local forward (Set `port: 3306', `host:
     localhost', `remote port: 3306').

  4. Save everything, otherwise you will have to redo it the next time.

  5. Log in to your server with the SSH session you just created.

  6. On your Windows machine, start some ODBC application (such as
     Access).

  7. Create a new file in Windows and link to MySQL using the ODBC
     driver the same way you normally do, except type in `localhost'
     for the MySQL host server, not YOURMYSQLSERVERNAME.

At this point, you should have an ODBC connection to MySQL, encrypted
using SSH.


File: manual.info,  Node: account-activity-auditing,  Prev: windows-and-ssh,  Up: user-account-management

5.5.9 Auditing MySQL Account Activity
-------------------------------------

Applications can use the following guidelines to perform auditing that
ties database activity to MySQL accounts.

MySQL accounts correspond to rows in the `mysql.user' table. When a
client connects successfully, the server authenticates the client to a
particular row in this table. The `User' and `Host' column values in
this row uniquely identify the account and correspond to the
`'USER_NAME'@'HOST_NAME'' format in which account names are written in
SQL statements.

The account used to authenticate a client determines which privileges
the client has. Normally, the `CURRENT_USER()' function can be invoked
to determine which account this is for the client user.  Its value is
constructed from the `User' and `Host' columns of the `user' table row
for the account.

However, there are circumstances under which the `CURRENT_USER()' value
corresponds not to the client user but to a different account. This
occurs in contexts when privilege checking is not based the client's
account:

   * Stored routines (procedures and functions) defined with the `SQL
     SECURITY DEFINER' characteristic

   * Views defined with the `SQL SECURITY DEFINER' characteristic

   * Triggers and events

In those contexts, privilege checking is done against the `DEFINER'
account and `CURRENT_USER()' refers to that account, not to the account
for the client who invoked the stored routine or view or who caused the
trigger to activate. To determine the invoking user, you can call the
`USER()' function, which returns a value indicating the actual user
name provided by the client and the host from which the client
connected. However, this value does not necessarily correspond directly
to an account in the `user' table, because the `USER()' value never
contains wildcards, whereas account values (as returned by
`CURRENT_USER()') may contain user name and host name wildcards.

For example, a blank user name matches any user, so an account of
`''@'localhost'' enables clients to connect as an anonymous user from
the local host with any user name. If this case, if a client connects
as `user1' from the local host, `USER()' and `CURRENT_USER()' return
different values:

     mysql> SELECT USER(), CURRENT_USER();
     +-----------------+----------------+
     | USER()          | CURRENT_USER() |
     +-----------------+----------------+
     | user1@localhost | @localhost     |
     +-----------------+----------------+

The host name part of an account can contain wildcards, too. If the
host name contains a `'%'' or `'_'' pattern character or uses netmask
notation, the account can be used for clients connecting from multiple
hosts and the `CURRENT_USER()' value will not indicate which one. For
example, the account `'user2'@'%.example.com'' can be used by `user2'
to connect from any host in the `example.com' domain. If `user2'
connects from `remote.example.com', `USER()' and `CURRENT_USER()'
return different values:

     mysql> SELECT USER(), CURRENT_USER();
     +--------------------------+---------------------+
     | USER()                   | CURRENT_USER()      |
     +--------------------------+---------------------+
     | user2@remote.example.com | user2@%.example.com |
     +--------------------------+---------------------+

If an application must invoke `USER()' for user auditing (for example,
if it does auditing from within triggers) but must also be able to
associate the `USER()' value with an account in the `user' table, it is
necessary to avoid accounts that contain wildcards in the `User' or
`Host' column.  Specifically, do not allow `User' to be empty (which
creates an anonymous-user account), and do not allow pattern characters
or netmask notation in `Host' values. All accounts must have a
non-empty `User' value and literal `Host' value.

With respect to the previous examples, the `''@'localhost'' and
`'user2'@'%.example.com'' accounts should be changed not to use
wildcards:

     RENAME USER ''@'localhost' TO 'user1'@'localhost';
     RENAME USER 'user2'@'%.example.com' TO 'user2'@'remote.example.com';

If `user2' must be able to connect from several hosts in the
`example.com' domain, there should be a separate account for each host.

To extract the user name or host name part from a `CURRENT_USER()' or
`USER()' value, use the `SUBSTRING()' function:

     mysql> SELECT SUBSTRING_INDEX(CURRENT_USER(),'@',1);
     +---------------------------------------+
     | SUBSTRING_INDEX(CURRENT_USER(),'@',1) |
     +---------------------------------------+
     | user1                                 |
     +---------------------------------------+

     mysql> SELECT SUBSTRING_INDEX(CURRENT_USER(),'@',-1);
     +----------------------------------------+
     | SUBSTRING_INDEX(CURRENT_USER(),'@',-1) |
     +----------------------------------------+
     | localhost                              |
     +----------------------------------------+


File: manual.info,  Node: multiple-servers,  Next: dba-dtrace-server,  Prev: user-account-management,  Up: server-administration

5.6 Running Multiple MySQL Servers on the Same Machine
======================================================

* Menu:

* multiple-windows-servers::     Running Multiple Servers on Windows
* multiple-unix-servers::        Running Multiple Servers on Unix
* multiple-server-clients::      Using Client Programs in a Multiple-Server Environment

In some cases, you might want to run multiple *Note `mysqld': mysqld.
servers on the same machine. You might want to test a new MySQL release
while leaving your existing production setup undisturbed. Or you might
want to give different users access to different *Note `mysqld':
mysqld. servers that they manage themselves. (For example, you might be
an Internet Service Provider that wants to provide independent MySQL
installations for different customers.)

To run multiple servers on a single machine, each server must have
unique values for several operating parameters. These can be set on the
command line or in option files. See *Note program-options::.

At least the following options must be different for each server:

   * `--port=PORT_NUM'

     `--port' controls the port number for TCP/IP connections.
     (Alternatively, if the host has multiple network addresses, you
     can use `--bind-address' to cause different servers to listen to
     different interfaces.)

   * `--socket=PATH'

     `--socket' controls the Unix socket file path on Unix and the name
     of the named pipe on Windows. On Windows, it is necessary to
     specify distinct pipe names only for those servers that support
     named-pipe connections.

   * `--shared-memory-base-name=NAME'

     This option currently is used only on Windows. It designates the
     shared-memory name used by a Windows server to allow clients to
     connect via shared memory. It is necessary to specify distinct
     shared-memory names only for those servers that support
     shared-memory connections.

   * `--pid-file=FILE_NAME'

     This option is used only on Unix. It indicates the path name of
     the file in which the server writes its process ID.

If you use the following log file options, they must be different for
each server:

   * `--general_log' or `--log[=FILE_NAME]'

   * `--log-bin[=FILE_NAME]'

   * `--slow_query_log' or `--log-slow-queries[=FILE_NAME]'

   * `--log-error[=FILE_NAME]'

*Note log-file-maintenance::, discusses the log file options further.

For better performance, you can specify the following options
differently for each server, to spread the load between several
physical disks:

   * `--tmpdir=PATH'

Having different temporary directories is also recommended to make it
easier to determine which MySQL server created any given temporary file.

With very limited exceptions, each server should use a different data
directory, which is specified using the `--datadir=PATH' option.

*Warning*:

Normally, you should never have two servers that update data in the
same databases. This may lead to unpleasant surprises if your operating
system does not support fault-free system locking. If (despite this
warning) you run multiple servers using the same data directory and
they have logging enabled, you must use the appropriate options to
specify log file names that are unique to each server. Otherwise, the
servers try to log to the same files.  Please note that this kind of
setup only works with `MyISAM' and `MERGE' tables, and not with any of
the other storage engines.

The warning against sharing a data directory among servers also applies
in an NFS environment. Allowing multiple MySQL servers to access a
common data directory over NFS is a _very bad idea_.

   * The primary problem is that NFS is the speed bottleneck. It is not
     meant for such use.

   * Another risk with NFS is that you must devise a way to ensure that
     two or more servers do not interfere with each other.  Usually NFS
     file locking is handled by the `lockd' daemon, but at the moment
     there is no platform that performs locking 100% reliably in every
     situation.

Make it easy for yourself: Forget about sharing a data directory among
servers over NFS. A better solution is to have one computer that
contains several CPUs and use an operating system that handles threads
efficiently.

If you have multiple MySQL installations in different locations, you
can specify the base installation directory for each server with the
`--basedir=PATH' option to cause each server to use a different data
directory, log files, and PID file. (The defaults for all these values
are determined relative to the base directory). In that case, the only
other options you need to specify are the `--socket' and `--port'
options. For example, suppose that you install different versions of
MySQL using `tar' file binary distributions. These install in different
locations, so you can start the server for each installation using the
command `bin/mysqld_safe' under its corresponding base directory.
*Note `mysqld_safe': mysqld-safe. determines the proper `--basedir'
option to pass to *Note `mysqld': mysqld, and you need specify only the
`--socket' and `--port' options to *Note `mysqld_safe': mysqld-safe.

As discussed in the following sections, it is possible to start
additional servers by setting environment variables or by specifying
appropriate command-line options. However, if you need to run multiple
servers on a more permanent basis, it is more convenient to use option
files to specify for each server those option values that must be
unique to it. The `--defaults-file' option is useful for this purpose.


File: manual.info,  Node: multiple-windows-servers,  Next: multiple-unix-servers,  Prev: multiple-servers,  Up: multiple-servers

5.6.1 Running Multiple Servers on Windows
-----------------------------------------

* Menu:

* multiple-windows-command-line-servers::  Starting Multiple Windows Servers at the Command Line
* multiple-windows-services::    Starting Multiple Windows Servers as Services

You can run multiple servers on Windows by starting them manually from
the command line, each with appropriate operating parameters.  On
Windows NT-based systems, you also have the option of installing
several servers as Windows services and running them that way. General
instructions for running MySQL servers from the command line or as
services are given in *Note windows-installation::. This section
describes how to make sure that you start each server with different
values for those startup options that must be unique per server, such
as the data directory. These options are described in *Note
multiple-servers::.


File: manual.info,  Node: multiple-windows-command-line-servers,  Next: multiple-windows-services,  Prev: multiple-windows-servers,  Up: multiple-windows-servers

5.6.1.1 Starting Multiple Windows Servers at the Command Line
.............................................................

To start multiple servers manually from the command line, you can
specify the appropriate options on the command line or in an option
file. It is more convenient to place the options in an option file, but
it is necessary to make sure that each server gets its own set of
options. To do this, create an option file for each server and tell the
server the file name with a `--defaults-file' option when you run it.

Suppose that you want to run *Note `mysqld': mysqld. on port 3307 with
a data directory of `C:\mydata1', and *Note `mysqld-debug': mysqld. on
port 3308 with a data directory of `C:\mydata2'. (To do this, make sure
that before you start the servers, each data directory exists and has
its own copy of the `mysql' database that contains the grant tables.)
Then create two option files. For example, create one file named
`C:\my-opts1.cnf' that looks like this:

     [mysqld]
     datadir = C:/mydata1
     port = 3307

Create a second file named `C:\my-opts2.cnf' that looks like this:

     [mysqld]
     datadir = C:/mydata2
     port = 3308

Then start each server with its own option file:

     C:\> C:\mysql\bin\mysqld --defaults-file=C:\my-opts1.cnf
     C:\> C:\mysql\bin\mysqld-debug --defaults-file=C:\my-opts2.cnf

On NT, each server starts in the foreground (no new prompt appears
until the server exits later), so you will need to issue those two
commands in separate console windows.

To shut down the servers, you must connect to each using the
appropriate port number:

     C:\> C:\mysql\bin\mysqladmin --port=3307 shutdown
     C:\> C:\mysql\bin\mysqladmin --port=3308 shutdown

Servers configured as just described allow clients to connect over
TCP/IP. If your version of Windows supports named pipes specify the
options that enable the named pipe and specify its name. Each server
that supports named-pipe connections must use a unique pipe name. For
example, the `C:\my-opts1.cnf' file might be written like this:

     [mysqld]
     datadir = C:/mydata1
     port = 3307
     enable-named-pipe
     socket = mypipe1

Then start the server this way:

     C:\> C:\mysql\bin\mysqld --defaults-file=C:\my-opts1.cnf

Modify `C:\my-opts2.cnf' similarly for use by the second server.

A similar procedure applies for servers that you want to support
shared-memory connections. Enable such connections with the
`--shared-memory' option and specify a unique shared-memory name for
each server with the `--shared-memory-base-name' option.


File: manual.info,  Node: multiple-windows-services,  Prev: multiple-windows-command-line-servers,  Up: multiple-windows-servers

5.6.1.2 Starting Multiple Windows Servers as Services
.....................................................

On NT-based systems, a MySQL server can run as a Windows service. The
procedures for installing, controlling, and removing a single MySQL
service are described in *Note windows-start-service::.

You can also install multiple MySQL servers as services. In this case,
you must make sure that each server uses a different service name in
addition to all the other parameters that must be unique for each
server.

For the following instructions, assume that you want to run the *Note
`mysqld': mysqld. server from two different versions of MySQL that are
installed at `C:\mysql-5.0.19' and `C:\mysql-6.0.12', respectively.
(This might be the case if you're running 5.0.19 as your production
server, but also want to conduct tests using 6.0.12.)

The following principles apply when installing a MySQL service with the
`--install' or `--install-manual' option:

   * If you specify no service name, the server uses the default
     service name of `MySQL' and the server reads options from the
     `[mysqld]' group in the standard option files.

   * If you specify a service name after the `--install' option, the
     server ignores the `[mysqld]' option group and instead reads
     options from the group that has the same name as the service. The
     server reads options from the standard option files.

   * If you specify a `--defaults-file' option after the service name,
     the server ignores the standard option files and reads options
     only from the `[mysqld]' group of the named file.

*Note*:

Before MySQL 4.0.17, only a server installed using the default service
name (`MySQL') or one installed explicitly with a service name of *Note
`mysqld': mysqld.  will read the `[mysqld]' group in the standard
option files. As of 4.0.17, all servers read the `[mysqld]' group if
they read the standard option files, even if they are installed using
another service name. This allows you to use the `[mysqld]' group for
options that should be used by all MySQL services, and an option group
named after each service for use by the server installed with that
service name.

Based on the preceding information, you have several ways to set up
multiple services. The following instructions describe some examples.
Before trying any of them, be sure that you shut down and remove any
existing MySQL services first.

   * *Approach 1:* Specify the options for all services in one of the
     standard option files. To do this, use a different service name
     for each server. Suppose that you want to run the 5.0.19 *Note
     `mysqld': mysqld. using the service name of `mysqld1' and the
     6.0.12 *Note `mysqld': mysqld. using the service name `mysqld2'.
     In this case, you can use the `[mysqld1]' group for 5.0.19 and the
     `[mysqld2]' group for 6.0.12.  For example, you can set up
     `C:\my.cnf' like this:

          # options for mysqld1 service
          [mysqld1]
          basedir = C:/mysql-5.0.19
          port = 3307
          enable-named-pipe
          socket = mypipe1

          # options for mysqld2 service
          [mysqld2]
          basedir = C:/mysql-6.0.12
          port = 3308
          enable-named-pipe
          socket = mypipe2

     Install the services as follows, using the full server path names
     to ensure that Windows registers the correct executable program
     for each service:

          C:\> C:\mysql-5.0.19\bin\mysqld --install mysqld1
          C:\> C:\mysql-6.0.12\bin\mysqld --install mysqld2

     To start the services, use the services manager, or use `NET
     START' with the appropriate service names:

          C:\> NET START mysqld1
          C:\> NET START mysqld2

     To stop the services, use the services manager, or use `NET STOP'
     with the appropriate service names:

          C:\> NET STOP mysqld1
          C:\> NET STOP mysqld2

   * *Approach 2:* Specify options for each server in separate files
     and use `--defaults-file' when you install the services to tell
     each server what file to use.  In this case, each file should list
     options using a `[mysqld]' group.

     With this approach, to specify options for the 5.0.19 *Note
     `mysqld': mysqld, create a file `C:\my-opts1.cnf' that looks like
     this:

          [mysqld]
          basedir = C:/mysql-5.0.19
          port = 3307
          enable-named-pipe
          socket = mypipe1

     For the 6.0.12 *Note `mysqld': mysqld, create a file
     `C:\my-opts2.cnf' that looks like this:

          [mysqld]
          basedir = C:/mysql-6.0.12
          port = 3308
          enable-named-pipe
          socket = mypipe2

     Install the services as follows (enter each command on a single
     line):

          C:\> C:\mysql-5.0.19\bin\mysqld --install mysqld1
                     --defaults-file=C:\my-opts1.cnf
          C:\> C:\mysql-6.0.12\bin\mysqld --install mysqld2
                     --defaults-file=C:\my-opts2.cnf

     To use a `--defaults-file' option when you install a MySQL server
     as a service, you must precede the option with the service name.

     After installing the services, start and stop them the same way as
     in the preceding example.

To remove multiple services, use *Note `mysqld --remove': mysqld. for
each one, specifying a service name following the `--remove' option. If
the service name is the default (`MySQL'), you can omit it.


File: manual.info,  Node: multiple-unix-servers,  Next: multiple-server-clients,  Prev: multiple-windows-servers,  Up: multiple-servers

5.6.2 Running Multiple Servers on Unix
--------------------------------------

The easiest way is to run multiple servers on Unix is to compile them
with different TCP/IP ports and Unix socket files so that each one is
listening on different network interfaces. Compiling in different base
directories for each installation also results automatically in a
separate, compiled-in data directory, log file, and PID file location
for each server.

Assume that an existing 5.0.19 server is configured for the default
TCP/IP port number (3306) and Unix socket file (`/tmp/mysql.sock'). To
configure a new 6.0.12 server to have different operating parameters,
use a `configure' command something like this:

     shell> ./configure --with-tcp-port=PORT_NUMBER \
                  --with-unix-socket-path=FILE_NAME \
                  --prefix=/usr/local/mysql-6.0.12

Here, PORT_NUMBER and FILE_NAME must be different from the default
TCP/IP port number and Unix socket file path name, and the `--prefix'
value should specify an installation directory different from the one
under which the existing MySQL installation is located.

If you have a MySQL server listening on a given port number, you can
use the following command to find out what operating parameters it is
using for several important configurable variables, including the base
directory and Unix socket file name:

     shell> mysqladmin --host=HOST_NAME --port=PORT_NUMBER variables

With the information displayed by that command, you can tell what
option values _not_ to use when configuring an additional server.

Note that if you specify `localhost' as a host name, *Note
`mysqladmin': mysqladmin. defaults to using a Unix socket file
connection rather than TCP/IP. From MySQL 4.1 onward, you can
explicitly specify the connection protocol to use by using the
`--protocol={TCP|SOCKET|PIPE|MEMORY}' option.

You don't have to compile a new MySQL server just to start with a
different Unix socket file and TCP/IP port number. It is also possible
to use the same server binary and start each invocation of it with
different parameter values at runtime. One way to do so is by using
command-line options:

     shell> mysqld_safe --socket=FILE_NAME --port=PORT_NUMBER

To start a second server, provide different `--socket' and `--port'
option values, and pass a `--datadir=PATH' option to *Note
`mysqld_safe': mysqld-safe. so that the server uses a different data
directory.

Another way to achieve a similar effect is to use environment variables
to set the Unix socket file name and TCP/IP port number:

     shell> MYSQL_UNIX_PORT=/tmp/mysqld-new.sock
     shell> MYSQL_TCP_PORT=3307
     shell> export MYSQL_UNIX_PORT MYSQL_TCP_PORT
     shell> mysql_install_db --user=mysql
     shell> mysqld_safe --datadir=/path/to/datadir &

This is a quick way of starting a second server to use for testing. The
nice thing about this method is that the environment variable settings
apply to any client programs that you invoke from the same shell. Thus,
connections for those clients are automatically directed to the second
server.

*Note environment-variables::, includes a list of other environment
variables you can use to affect *Note `mysqld': mysqld.

For automatic server execution, the startup script that is executed at
boot time should execute the following command once for each server
with an appropriate option file path for each command:

     shell> mysqld_safe --defaults-file=FILE_NAME

Each option file should contain option values specific to a given
server.

On Unix, the *Note `mysqld_multi': mysqld-multi. script is another way
to start multiple servers. See *Note mysqld-multi::.


File: manual.info,  Node: multiple-server-clients,  Prev: multiple-unix-servers,  Up: multiple-servers

5.6.3 Using Client Programs in a Multiple-Server Environment
------------------------------------------------------------

To connect with a client program to a MySQL server that is listening to
different network interfaces from those compiled into your client, you
can use one of the following methods:

   * Start the client with `--host=HOST_NAME' `--port=PORT_NUMBER' to
     connect via TCP/IP to a remote server, with `--host=127.0.0.1'
     `--port=PORT_NUMBER' to connect via TCP/IP to a local server, or
     with `--host=localhost' `--socket=FILE_NAME' to connect to a local
     server via a Unix socket file or a Windows named pipe.

   * As of MySQL 4.1, start the client with `--protocol=TCP' to connect
     via TCP/IP, `--protocol=SOCKET' to connect via a Unix socket file,
     `--protocol=PIPE' to connect via a named pipe, or
     `--protocol=MEMORY' to connect via shared memory. For TCP/IP
     connections, you may also need to specify `--host' and `--port'
     options. For the other types of connections, you may need to
     specify a `--socket' option to specify a Unix socket file or
     Windows named-pipe name, or a `--shared-memory-base-name' option
     to specify the shared-memory name. Shared-memory connections are
     supported only on Windows.

   * On Unix, set the `MYSQL_UNIX_PORT' and `MYSQL_TCP_PORT'
     environment variables to point to the Unix socket file and TCP/IP
     port number before you start your clients. If you normally use a
     specific socket file or port number, you can place commands to set
     these environment variables in your `.login' file so that they
     apply each time you log in. See *Note environment-variables::.

   * Specify the default Unix socket file and TCP/IP port number in the
     `[client]' group of an option file. For example, you can use
     `C:\my.cnf' on Windows, or the `.my.cnf' file in your home
     directory on Unix. See *Note option-files::.

   * In a C program, you can specify the socket file or port number
     arguments in the *Note `mysql_real_connect()': mysql-real-connect.
     call. You can also have the program read option files by calling
     *Note `mysql_options()': mysql-options. See *Note
     c-api-functions::.

   * If you are using the Perl `DBD::mysql' module, you can read
     options from MySQL option files. For example:

          $dsn = "DBI:mysql:test;mysql_read_default_group=client;"
                  . "mysql_read_default_file=/usr/local/mysql/data/my.cnf";
          $dbh = DBI->connect($dsn, $user, $password);

     See *Note apis-perl::.

     Other programming interfaces may provide similar capabilities for
     reading option files.


File: manual.info,  Node: dba-dtrace-server,  Prev: multiple-servers,  Up: server-administration

5.7 Tracing `mysqld' Using DTrace
=================================

* Menu:

* dba-dtrace-mysqld-ref::        `mysqld' DTrace Probe Reference

The DTrace probes in the MySQL server are designed to provide
information about the execution of queries within MySQL and the
different areas of the system being utilized during that process.  The
organization and triggering of the probes means that the execution of
an entire query can be monitored with one level of probes
(`query-start' and `query-done') but by monitoring other probes you can
get successively more detailed information about the execution of the
query in terms of the locks used, sort methods and even row-by-row and
storage-engine level execution information.

The DTrace probes are organized so that you can follow the entire query
process, from the point of connection from a client, through the query
execution, row-level operations, and back out again. You can think of
the probes as being fired within a specific sequence during a typical
client connect/execute/disconnect sequence, as shown in the following
figure.

FIGURE GOES HERE: The MySQL architecture using pluggable storage engines

Global information is provided in the arguments to the DTrace probes at
various levels. Global information, that is, the connection ID and
user/host and where relevant the query string, is provided at key
levels (`connection-start', `command-start', `query-start', and
`query-exec-start'). As you go deeper into the probes, it is assumed
either you are only interested in the individual executions (row-level
probes provide information on the database and table name only), or
that you will combine the row-level probes with the notional parent
probes to provide the information about a specific query. Examples of
this will be given as the format and arguments of each probe are
provided.

For more information on DTrace and writing DTrace scripts, read the
DTrace User Guide (http://docs.sun.com/app/docs/doc/819-5488?l=en).

Support for DTrace probes was added in MySQL 6.0.4, with the
recommended list of probes supported in MySQL 6.0.8 and higher.  DTrace
probes in MySQL are supported on Solaris 10 Update 5 (Solaris 5/08),
and OpenSolaris 2008.05 and higher on SPARC, x86 and x86_64 platforms.
Enabling the probes should be automatic on these platforms. To
explicitly enable or disable the probes during building, use the
`--enable-dtrace' or `--disable-dtrace' option to `configure'.


File: manual.info,  Node: dba-dtrace-mysqld-ref,  Prev: dba-dtrace-server,  Up: dba-dtrace-server

5.7.1 `mysqld' DTrace Probe Reference
-------------------------------------

* Menu:

* dba-dtrace-ref-connection::    Connection Probes
* dba-dtrace-ref-command::       Command Probes
* dba-dtrace-ref-query::         Query Probes
* dba-dtrace-ref-query-parsing::  Query Parsing Probes
* dba-dtrace-ref-querycache::    Query Cache Probes
* dba-dtrace-ref-queryexec::     Query Execution Probes
* dba-dtrace-ref-rowlevel::      Row-Level Probes
* dba-dtrace-ref-lock::          Lock Probes
* dba-dtrace-ref-filesort::      Filesort Probes
* dba-dtrace-ref-statement::     Statement Probes
* dba-dtrace-ref-network::       Network Probes

MySQL supports the following static probes, organized into groups of
functionality, starting with MySQL 6.0.8.

*MySQL DTrace Probes*

Group          Probes                                             Introduced
*Note          `connection-start', `connection-done'              6.0.8
Connection:                                                       
dba-dtrace-ref-connection.                                                   
*Note          `command-start', `command-done'                    6.0.8
Command:                                                          
dba-dtrace-ref-command.                                                   
*Note Query:   `query-start', `query-done'                        6.0.8
dba-dtrace-ref-query.                                                   
*Note Query    `query-parse-start', `query-parse-done'            6.0.8
Parsing:                                                          
dba-dtrace-ref-query-parsing.                                                   
*Note Query    `query-cache-hit', `query-cache-miss'              6.0.8
Cache:                                                            
dba-dtrace-ref-querycache.                                                   
*Note Query    `query-exec-start', `query-exec-done'              6.0.8
Execution:                                                        
dba-dtrace-ref-queryexec.                                                   
*Note Row      `insert-row-start', `insert-row-done'              6.0.8
Level:                                                            
dba-dtrace-ref-rowlevel.                                                   
               `update-row-start', `update-row-done'              6.0.8
               `delete-row-start', `delete-row-done'              6.0.8
*Note Lock:    `handler-rdlock-start', `handler-rdlock-done'      6.0.8
dba-dtrace-ref-lock.                                                   
               `handler-wrlock-start', `handler-wrlock-done'      6.0.8
               `handler-unlock-start', `handler-unlock-done'      6.0.8
*Note          `filesort-start', `filesort-done'                  6.0.8
Filesort:                                                         
dba-dtrace-ref-filesort.                                                   
*Note          `select-start', `select-done'                      6.0.8
Statement:                                                        
dba-dtrace-ref-statement.                                                   
               `insert-start', `insert-done'                      6.0.8
               `insert-select-start', `insert-select-done'        6.0.8
               `update-start ', `update-done'                     6.0.8
               `multi-update-start', `multi-update-done'          6.0.8
               `delete-start', `delete-done'                      6.0.8
               `multi-delete-start', `multi-delete-done'          6.0.8
*Note          `net-read-start', `net-read-done',                 6.0.8
Network:       `net-write-start', `net-write-done'                
dba-dtrace-ref-network.                                                   

*Note*:

When extracting the argument data from the probes, each argument is
available as `argN', starting with `arg0'. To identify each argument
within the definitions they are provided with a descriptive name, but
you must access the information using the corresponding `argN'
parameter.


File: manual.info,  Node: dba-dtrace-ref-connection,  Next: dba-dtrace-ref-command,  Prev: dba-dtrace-mysqld-ref,  Up: dba-dtrace-mysqld-ref

5.7.1.1 Connection Probes
.........................

The `connection-start' and `connection-done' probes enclose a connection
from a client, regardless of whether the connection is through a socket
or network connection.

     connection-start(connectionid, user, host)
     query-done(status, connectionid)

   * `connection-start' -- is triggered after a connection and
     successful login/authentication have been completed by a client.
     The arguments contain the connection information:

        * `connectionid' -- is an `unsigned long' containing the
          connection ID. This is the same as the process ID shown as
          the `Id' value in the output from *Note `SHOW PROCESSLIST':
          show-processlist.

        * `user' -- is the username used when authenticating. The value
          will be blank for the anonymous user.

        * `host' -- is the host of the client connection. For a
          connection made using UNIX sockets, the value will be blank.

   * `connection-done' -- is triggered just as the connection to the
     client has been closed. The arguments are:

        * `status' -- the status of the connection when it was closed.
          A logout operation will have a value of 0; any other
          termination of the connection has a non-zero value.

        * `connectionid' -- the connection ID of the connection that
          was closed.

The following D script will quantify and summarize the average duration
of individual connections, and provide a count, dumping the information
every 60 seconds:

     #!/usr/sbin/dtrace -s

     mysql*:::connection-start
     {
       self->start = timestamp;
     }

     mysql*:::connection-done
     /self->start/
     {
       @ = quantize(((timestamp - self->start)/1000000));
       self->start = 0;
     }

     tick-60s
     {
       printa(@);
     }

When executed on a server with a large number of clients you might see
output similar to this:

       1  57413                        :tick-60s

                value  ------------- Distribution ------------- count
                   -1 |                                         0
                    0 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 30011
                    1 |                                         59
                    2 |                                         5
                    4 |                                         20
                    8 |                                         29
                   16 |                                         18
                   32 |                                         27
                   64 |                                         30
                  128 |                                         11
                  256 |                                         10
                  512 |                                         1
                 1024 |                                         6
                 2048 |                                         8
                 4096 |                                         9
                 8192 |                                         8
                16384 |                                         2
                32768 |                                         1
                65536 |                                         1
               131072 |                                         0
               262144 |                                         1
               524288 |                                         0


File: manual.info,  Node: dba-dtrace-ref-command,  Next: dba-dtrace-ref-query,  Prev: dba-dtrace-ref-connection,  Up: dba-dtrace-mysqld-ref

5.7.1.2 Command Probes
......................

The command probes are executed before and after a client command is
executed, including any SQL statement that might be executed during
that period. Commands include operations such as the initialization of
the DB, use of the `COM_CHANGE_USER' operation (supported by the MySQL
protocol), and manipulation of prepared statements. Many of these
commands are used only by the MySQL client API from various connectors
such as PHP and Java.

     command-start(connectionid, command, user, host)
     command-done(status)

   * `command-start' -- triggered when a command is submitted to the
     server.

        * `connectionid' -- the connection ID of the client executing
          the command.

        * `command' -- an integer representing the command that was
          executed. Possible values are shown in the following table.

          Value  Name         Description
          00     COM_SLEEP    Internal thread state
          01     COM_QUIT     Close connection
          02     COM_INIT_DB  Select database (`USE ...')
          03     COM_QUERY    Execute a query
          04     COM_FIELD_LISTGet a list of fields
          05     COM_CREATE_DBCreate a database (deprecated)
          06     COM_DROP_DB  Drop a database (deprecated)
          07     COM_REFRESH  Refresh connection
          08     COM_SHUTDOWN Shutdown server
          09     COM_STATISTICSGet statistics
          10     COM_PROCESS_INFOGet processes (*Note `SHOW PROCESSLIST':
                              show-processlist.)
          11     COM_CONNECT  Initialize connection
          12     COM_PROCESS_KILLKill process
          13     COM_DEBUG    Get debug information
          14     COM_PING     Ping
          15     COM_TIME     Internal thread state
          16     COM_DELAYED_INSERTInternal thread state
          17     COM_CHANGE_USERChange user
          18     COM_BINLOG_DUMPUsed by a replication slave or *Note
                              `mysqlbinlog': mysqlbinlog. to initiate a
                              binary log read
          19     COM_TABLE_DUMPUsed by a replication slave to get the
                              master table information
          20     COM_CONNECT_OUTUsed by a replication slave to log a
                              connection to the server
          21     COM_REGISTER_SLAVEUsed by a replication slave during
                              registration
          22     COM_STMT_PREPAREPrepare a statement
          23     COM_STMT_EXECUTEExecute a statement
          24     COM_STMT_SEND_LONG_DATAUsed by a client when requesting extended
                              data
          25     COM_STMT_CLOSEClose a prepared statement
          26     COM_STMT_RESETReset a prepared statement
          27     COM_SET_OPTIONSet a server option
          28     COM_STMT_FETCHFetch a prepared statement

        * `user' -- the user executing the command.

        * `host' -- the client host.

   * `command-done' -- triggered when the command execution completes.
     The `status' argument contains 0 if the command executed
     successfully, or 1 if the statement was terminated before normal
     completion.

The `command-start' and `command-done' probes are best used when
combined with the statement probes to get an idea of overall execution
time.


File: manual.info,  Node: dba-dtrace-ref-query,  Next: dba-dtrace-ref-query-parsing,  Prev: dba-dtrace-ref-command,  Up: dba-dtrace-mysqld-ref

5.7.1.3 Query Probes
....................

The `query-start' and `query-done' probes are triggered when a specific
query is received by the server and when the query has been completed
and the information has been successfully sent to the client.

     query-start(query, connectionid, database, user, host)
     query-done(status)

   * `query-start' -- is triggered after the query string has been
     received from the client. The arguments are:

        * `query' -- the full text of the submitted query.

        * `connectionid' -- the connection ID of the client that
          submitted the query. The connection ID equals the connection
          ID returned when the client first connects and the `Id' value
          in the output from *Note `SHOW PROCESSLIST': show-processlist.

        * `database' -- the database name on which the query is being
          executed.

        * `user' -- the username used to connect to the server.

        * `host' -- the hostname of the client.

   * `query-done' -- is triggered once the query has been executed and
     the information has been returned to the client. The probe
     includes a single argument, `status', which returns 0 when the
     query is successfully executed and 1 if there was an error.

You can get a simple report of the execution time for each query using
the following D script:

     #!/usr/sbin/dtrace -s

     #pragma D option quiet

     dtrace:::BEGIN
     {
        printf("%-20s %-20s %-40s %-9s\n", "Who", "Database", "Query", "Time(ms)");
     }

     mysql*:::query-start
     {
        self->query = copyinstr(arg0);
        self->connid = arg1;
        self->db    = copyinstr(arg2);
        self->who   = strjoin(copyinstr(arg3),strjoin("@",copyinstr(arg4)));
        self->querystart = timestamp;
     }

     mysql*:::query-done
     {
        printf("%-20s %-20s %-40s %-9d\n",self->who,self->db,self->query,
               (timestamp - self->querystart) / 1000000);
     }

When executing the above script you should get a basic idea of the
execution time of your queries:

     shell> ./query.d
     Who                  Database             Query                                    Time(ms)
     root@localhost       test                 select * from t1 order by i limit 10     0
     root@localhost       test                 set global query_cache_size=0            0
     root@localhost       test                 select * from t1 order by i limit 10     776
     root@localhost       test                 select * from t1 order by i limit 10     773
     root@localhost       test                 select * from t1 order by i desc limit 10 795


File: manual.info,  Node: dba-dtrace-ref-query-parsing,  Next: dba-dtrace-ref-querycache,  Prev: dba-dtrace-ref-query,  Up: dba-dtrace-mysqld-ref

5.7.1.4 Query Parsing Probes
............................

The query parsing probes are triggered before the original SQL
statement is parsed and when the parsing of the statement and
determination of the execution model required to process the statement
has been completed:

     query-parse-start(query)
     query-parse-done(status)

   * `query-parse-start' -- is triggered just before the statement is
     parsed by the MySQL query parser. The single argument, `query', is
     a string containing the full text of the original query.

   * `query-parse-done' -- is triggered when the parsing of the
     original statement has been completed. The `status' is an integer
     describing the status of the operation. A `0' indicates that the
     query was successfully parsed. A `1' indicates that the parsing of
     the query failed.

For example, you could monitor the execution time for parsing a given
query using the following D script:

     #!/usr/sbin/dtrace -s

     #pragma D option quiet

     mysql*:::query-parse-start
     {
        self->parsestart = timestamp;
        self->parsequery = copyinstr(arg0);
     }

     mysql*:::query-parse-done
     /arg0 == 0/
     {
        printf("Parsing %s: %d microseconds\n", self->parsequery,((timestamp - self->parsestart)/1000));
     }

     mysql*:::query-parse-done
     /arg0 != 0/
     {
        printf("Error parsing %s: %d microseconds\n", self->parsequery,((timestamp - self->parsestart)/1000));
     }

In the above script a predicate is used on `query-parse-done' so that
different output is generated based on the status value of the probe.

When running the script and monitoring the execution:

     shell> ./query-parsing.d
     Error parsing select from t1 join (t2) on (t1.i = t2.i) order by t1.s,t1.i limit 10: 36 ms
     Parsing select * from t1 join (t2) on (t1.i = t2.i) order by t1.s,t1.i limit 10: 176 ms


File: manual.info,  Node: dba-dtrace-ref-querycache,  Next: dba-dtrace-ref-queryexec,  Prev: dba-dtrace-ref-query-parsing,  Up: dba-dtrace-mysqld-ref

5.7.1.5 Query Cache Probes
..........................

The query cache probes are fired when executing any query. The
`query-cache-hit' query is triggered when a query exists in the query
cache and can be used to return the query cache information. The
arguments contain the original query text and the number of rows
returned from the query cache for the query. If the query is not within
the query cache, or the query cache is not enabled, then the
`query-cache-miss' probe is triggered instead.

     query-cache-hit(query, rows)
     query-cache-miss(query)

   * `query-cache-hit' -- triggered when the query has been found
     within the query cache. The first argument, `query', contains the
     original text of the query. The second argument, `rows', is an
     integer containing the number of rows in the cached query.

   * `query-cache-misss' -- triggered when the query is not found
     within the query cache. The first argument, `query', contains the
     original text of the query.

The query cache probes are best combined with a probe on the main query
so that you can determine the differences in times between using or not
using the query cache for specified queries. For example, in the
following D script, the query and query cache information are combined
into the information output during monitoring:

     #!/usr/sbin/dtrace -s

     #pragma D option quiet

     dtrace:::BEGIN
     {
        printf("%-20s %-20s %-40s %2s %-9s\n", "Who", "Database", "Query", "QC", "Time(ms)");
     }

     mysql*:::query-start
     {
        self->query = copyinstr(arg0);
        self->connid = arg1;
        self->db    = copyinstr(arg2);
        self->who   = strjoin(copyinstr(arg3),strjoin("@",copyinstr(arg4)));
        self->querystart = timestamp;
        self->qc = 0;
     }

     mysql*:::query-cache-hit
     {
        self->qc = 1;
     }

     mysql*:::query-cache-miss
     {
        self->qc = 0;
     }

     mysql*:::query-done
     {
        printf("%-20s %-20s %-40s %-2s %-9d\n",self->who,self->db,self->query,(self->qc ? "Y" : "N"),
               (timestamp - self->querystart) / 1000000);
     }

When executing the script you can see the effects of the query cache.
Initially the query cache is disabled. If you set the query cache size
and then execute the query multiple times you should see that the query
cache is being used to return the query data:

     shell> ./query-cache.d
     root@localhost       test                 select * from t1 order by i limit 10     N  1072
     root@localhost                            set global query_cache_size=262144       N  0
     root@localhost       test                 select * from t1 order by i limit 10     N  781
     root@localhost       test                 select * from t1 order by i limit 10     Y  0


File: manual.info,  Node: dba-dtrace-ref-queryexec,  Next: dba-dtrace-ref-rowlevel,  Prev: dba-dtrace-ref-querycache,  Up: dba-dtrace-mysqld-ref

5.7.1.6 Query Execution Probes
..............................

The query execution probe is triggered when the actual execution of the
query starts, after the parsing and checking the query cache but before
any privilege checks or optimization. By comparing the difference
between the start and done probes you can monitor the time actually
spent servicing the query (instead of just handling the parsing and
other elements of the query).

     query-exec-start(query, connectionid, database, user, host, exec_type)
     query-exec-done(status)

     *Note*:

     The information provided in the arguments for `query-start' and
     `query-exec-start' are almost identical and designed so that you
     can choose to monitor either the entire query process (using
     `query-start') or only the execution (using `query-exec-start')
     while exposing the core information about the user, client, and
     query being executed.

   * `query-exec-start' -- is triggered when the execution of a
     individual query is started. The arguments are:

        * `query' -- the full text of the submitted query.

        * `connectionid' -- the connection ID of the client that
          submitted the query. The connection ID equals the connection
          ID returned when the client first connects and the `Id' value
          in the output from *Note `SHOW PROCESSLIST': show-processlist.

        * `database' -- the database name on which the query is being
          executed.

        * `user' -- the username used to connect to the server.

        * `host' -- the hostname of the client.

        * `exec_type' -- the type of execution. Execution types are
          determined based on the contents of the query and where it
          was submitted. The values for each type are shown in the
          following table.

          Value  Description
          0      Executed query from sql_parse, top-level query.
          1      Executed prepared statement
          2      Executed cursor statement
          3      Executed query in stored procedure

   * `query-exec-done' -- is triggered when the execution of the query
     has completed. The probe includes a single argument, `status',
     which returns 0 when the query is successfully executed and 1 if
     there was an error.


File: manual.info,  Node: dba-dtrace-ref-rowlevel,  Next: dba-dtrace-ref-lock,  Prev: dba-dtrace-ref-queryexec,  Up: dba-dtrace-mysqld-ref

5.7.1.7 Row-Level Probes
........................

The `*row-{start,done}' probes are triggered each time a row operation
is pushed down to a storage engine.  For example, if you execute an
*Note `INSERT': insert. statement with 100 rows of data, then the
`insert-row-start' and `insert-row-done' probes will be triggered 100
times each, for each row insert.

     insert-row-start(database, table)
     insert-row-done(status)

     update-row-start(database, table)
     update-row-done(status)

     delete-row-start(database, table)
     delete-row-done(status)

   * `insert-row-start' -- is triggered before a row is inserted into a
     table.

   * `insert-row-done' -- is triggered after a row is inserted into a
     table.

   * `update-row-start' -- is triggered before a row is updated in a
     table.

   * `update-row-done' -- is triggered before a row is updated in a
     table.

   * `delete-row-start' -- is triggered before a row is deleted from a
     table.

   * `delete-row-done' -- is triggered before a row is deleted from a
     table.

The arguments supported by the probes are consistent for the
corresponding `start' and `done' probes in each case:

   * `database' -- the database name.

   * `table' -- the table name.

   * `status' -- the status; 0 for success or 1 for failure.

Because the row-level probes are triggered for each individual row
access, these probes can be triggered many thousands of times each
second, which may have a detrimental effect on both the monitoring
script and MySQL. The DTrace environment should limit the triggering on
these probes to prevent the performance being adversely affected.
Either use the probes sparingly, or use counter or aggregation
functions to report on these probes and then provide a summary when the
script terminates or as part of a `query-done' or `query-exec-done'
probes.

The following example script summarizes the duration of each row
operation within a larger query:

     #!/usr/sbin/dtrace -s

     #pragma D option quiet

     dtrace:::BEGIN
     {
        printf("%-2s %-10s %-10s %9s %9s %-s \n",
               "St", "Who", "DB", "ConnID", "Dur ms", "Query");
     }

     mysql*:::query-start
     {
        self->query = copyinstr(arg0);
        self->who   = strjoin(copyinstr(arg3),strjoin("@",copyinstr(arg4)));
        self->db    = copyinstr(arg2);
        self->connid = arg1;
        self->querystart = timestamp;
        self->rowdur = 0;
     }

     mysql*:::query-done
     {
        this->elapsed = (timestamp - self->querystart) /1000000;
        printf("%2d %-10s %-10s %9d %9d %s\n",
               arg0, self->who, self->db,
               self->connid, this->elapsed, self->query);
     }

     mysql*:::query-done
     / self->rowdur /
     {
        printf("%34s %9d %s\n", "", (self->rowdur/1000000), "-> Row ops");
     }

     mysql*:::insert-row-start
     {
        self->rowstart = timestamp;
     }

     mysql*:::delete-row-start
     {
        self->rowstart = timestamp;
     }

     mysql*:::update-row-start
     {
        self->rowstart = timestamp;
     }

     mysql*:::insert-row-done
     {
        self->rowdur += (timestamp-self->rowstart);
     }

     mysql*:::delete-row-done
     {
        self->rowdur += (timestamp-self->rowstart);
     }

     mysql*:::update-row-done
     {
        self->rowdur += (timestamp-self->rowstart);
     }

Running the above script with a query that inserts data into a table,
you can monitor the exact time spent performing the raw row insertion:

     St Who        DB            ConnID    Dur ms Query
      0 @localhost test              13     20767 insert into t1(select * from t2)
                                             4827 -> Row ops


File: manual.info,  Node: dba-dtrace-ref-lock,  Next: dba-dtrace-ref-filesort,  Prev: dba-dtrace-ref-rowlevel,  Up: dba-dtrace-mysqld-ref

5.7.1.8 Lock Probes
...................

The lock probes are called whenever an external lock is requested by
MySQL for a table using the correspnding lock mechanism on the table as
defined by the table's engine type.  There are three different types of
lock, the read lock, write lock, and unlock operations. Using the
probes you can determine the duration of the external locking routine
(that is, the time taken by the storage engine to implement the lock,
including any time waiting for another lock to become free) and the
total duration of the lock/unlock process.

     handler-rdlock-start(database, table)
     handler-rdlock-done(status)

     handler-wrlock-start(database, table)
     handler-wrlock-done(status)

     handler-unlock-start(database, table)
     handler-unlock-done(status)

   * `handler-rdlock-start' -- triggered when a read lock is requested
     on the specified `database' and `table'.

   * `handler-wrlock-start' -- triggered when a write lock is requested
     on the specified `database' and `table'.

   * `handler-unlock-start' -- triggered when an unlock request is made
     on the specified `database' and `table'.

   * `handler-rdlock-done' -- triggered when a read lock request
     completes. The `status' is 0 if the lock operation succeeded, or
     `>0' on failure.

   * `handler-wrlock-done' -- triggered when a write lock request
     completes. The `status' is 0 if the lock operation succeeded, or
     `>0' on failure.

   * `handler-unlock-done' -- triggered when an unlock request
     completes. The `status' is 0 if the unlock operation succeeded, or
     `>0' on failure.

You can use arrays to monitor the locking and unlocking of individual
tables and then calculate the duration of the entire table lock using
the following script:

     #!/usr/sbin/dtrace -s

     #pragma D option quiet

     mysql*:::handler-rdlock-start
     {
        self->rdlockstart = timestamp;
        this->lockref = strjoin(copyinstr(arg0),strjoin("@",copyinstr(arg1)));
        self->lockmap[this->lockref] = self->rdlockstart;
        printf("Start: Lock->Read   %s.%s\n",copyinstr(arg0),copyinstr(arg1));
     }

     mysql*:::handler-wrlock-start
     {
        self->wrlockstart = timestamp;
        this->lockref = strjoin(copyinstr(arg0),strjoin("@",copyinstr(arg1)));
        self->lockmap[this->lockref] = self->rdlockstart;
        printf("Start: Lock->Write  %s.%s\n",copyinstr(arg0),copyinstr(arg1));
     }

     mysql*:::handler-unlock-start
     {
        self->unlockstart = timestamp;
        this->lockref = strjoin(copyinstr(arg0),strjoin("@",copyinstr(arg1)));
        printf("Start: Lock->Unlock %s.%s (%d ms lock duration)\n",
               copyinstr(arg0),copyinstr(arg1),
               (timestamp - self->lockmap[this->lockref])/1000000);
     }

     mysql*:::handler-rdlock-done
     {
        printf("End:   Lock->Read   %d ms\n",
               (timestamp - self->rdlockstart)/1000000);
     }

     mysql*:::handler-wrlock-done
     {
        printf("End:   Lock->Write  %d ms\n",
               (timestamp - self->wrlockstart)/1000000);
     }

     mysql*:::handler-unlock-done
     {
        printf("End:   Lock->Unlock %d ms\n",
               (timestamp - self->unlockstart)/1000000);
     }

When executed, you should get information both about the duration of
the locking process itself, and of the locks on a specific table:

     Start: Lock->Read   test.t2
     End:   Lock->Read   0 ms
     Start: Lock->Unlock test.t2 (25743 ms lock duration)
     End:   Lock->Unlock 0 ms
     Start: Lock->Read   test.t2
     End:   Lock->Read   0 ms
     Start: Lock->Unlock test.t2 (1 ms lock duration)
     End:   Lock->Unlock 0 ms
     Start: Lock->Read   test.t2
     End:   Lock->Read   0 ms
     Start: Lock->Unlock test.t2 (1 ms lock duration)
     End:   Lock->Unlock 0 ms
     Start: Lock->Read   test.t2
     End:   Lock->Read   0 ms


File: manual.info,  Node: dba-dtrace-ref-filesort,  Next: dba-dtrace-ref-statement,  Prev: dba-dtrace-ref-lock,  Up: dba-dtrace-mysqld-ref

5.7.1.9 Filesort Probes
.......................

The filesort probes are triggered whenever a filesort operation is
applied to a table. For more information on filesort and the conditions
under which it occurs, see *Note order-by-optimization::.

     filesort-start(database, table)
     filesort-done(status, rows)

   * `filesort-start' -- is triggered when the filesort operation
     starts on a table. The two arguments to the probe, `database' and
     `table', will identify the table being sorted.

   * `filesort-done' -- is triggered when the filesort operation
     completes. Two arguments are supplied, the `status' (0 for
     success, 1 for failure), and the number of rows sorted during the
     filesort process.

An example of this is in the following script, which tracks the
duration of the filesort process in addition to the duration of the
main query:

     #!/usr/sbin/dtrace -s

     #pragma D option quiet

     dtrace:::BEGIN
     {
        printf("%-2s %-10s %-10s %9s %18s %-s \n",
               "St", "Who", "DB", "ConnID", "Dur microsec", "Query");
     }

     mysql*:::query-start
     {
        self->query = copyinstr(arg0);
        self->who   = strjoin(copyinstr(arg3),strjoin("@",copyinstr(arg4)));
        self->db    = copyinstr(arg2);
        self->connid = arg1;
        self->querystart = timestamp;
        self->filesort = 0;
        self->fsdb = "";
        self->fstable = "";
     }

     mysql*:::filesort-start
     {
       self->filesort = timestamp;
       self->fsdb = copyinstr(arg0);
       self->fstable = copyinstr(arg1);
     }

     mysql*:::filesort-done
     {
        this->elapsed = (timestamp - self->filesort) /1000;
        printf("%2d %-10s %-10s %9d %18d Filesort on %s\n",
               arg0, self->who, self->fsdb,
               self->connid, this->elapsed, self->fstable);
     }

     mysql*:::query-done
     {
        this->elapsed = (timestamp - self->querystart) /1000;
        printf("%2d %-10s %-10s %9d %18d %s\n",
               arg0, self->who, self->db,
               self->connid, this->elapsed, self->query);
     }

Executing a query on a large table with an `ORDER BY' clause that
triggers a filesort, and then creating an index on the table and then
repeating the same query, you can see the difference in execution speed:

     St Who        DB            ConnID       Dur microsec Query
      0 @localhost test              14           11335469 Filesort on t1
      0 @localhost test              14           11335787 select * from t1 order by i limit 100
      0 @localhost test              14          466734378 create index t1a on t1 (i)
      0 @localhost test              14              26472 select * from t1 order by i limit 100


File: manual.info,  Node: dba-dtrace-ref-statement,  Next: dba-dtrace-ref-network,  Prev: dba-dtrace-ref-filesort,  Up: dba-dtrace-mysqld-ref

5.7.1.10 Statement Probes
.........................

The individual statement probes are provided to give specific
information about different statement types. For the start probes the
string of the query is provided as a the only argument. Depending on
the statement type, the information provided by the corresponding done
probe will differ. For all done probes the status of the operation (`0'
for success, `>0' for failure) is provided.  For *Note `SELECT': select,
*Note `INSERT': insert, *Note `INSERT ... (SELECT FROM ...)': insert,
*Note `DELETE': delete, and *Note `DELETE FROM t1,t2': delete.
operations the number of rows affected is returned.

For *Note `UPDATE': update. and *Note `UPDATE t1,t2 ...': update.
statements the number of rows matched and the number of rows actually
changed is provided. This is because the number of rows actually
matched by the corresponding `WHERE' clause, and the number of rows
changed can differ. MySQL does not update the value of a row if the
value already matches the new setting.

     select-start(query)
     select-done(status,rows)

     insert-start(query)
     insert-done(status,rows)

     insert-select-start(query)
     insert-select-done(status,rows)

     update-start(query)
     update-done(status,rowsmatched,rowschanged)

     multi-update-start(query)
     multi-update-done(status,rowsmatched,rowschanged)

     delete-start(query)
     delete-done(status,rows)

     multi-delete-start(query)
     multi-delete-done(status,rows)

   * `select-start' -- triggered before a *Note `SELECT': select.
     statement.

   * `select-done' -- triggered at the end of a *Note `SELECT': select.
     statement.

   * `insert-start' -- triggered before a *Note `INSERT': insert.
     statement.

   * `insert-done' -- triggered at the end of an *Note `INSERT':
     insert. statement.

   * `insert-select-start' -- triggered before an *Note `INSERT ...
     SELECT': insert. statement.

   * `insert-select-done' -- triggered at the end of an *Note `INSERT
     ... SELECT': insert. statement.

   * `update-start' -- triggered before an *Note `UPDATE': update.
     statement.

   * `update-done' -- triggered at the end of an *Note `UPDATE':
     update. statement.

   * `multi-update-start' -- triggered before an *Note `UPDATE':
     update. statement involving multiple tables.

   * `multi-update-done' -- triggered at the end of an *Note `UPDATE':
     update.  statement involving multiple tables.

   * `delete-start' -- triggered before a *Note `DELETE': delete.
     statement.

   * `delete-done' -- triggered at the end of a *Note `DELETE': delete.
     statement.

   * `multi-delete-start' -- triggered before a *Note `DELETE': delete.
     statement involving multiple tables.

   * `multi-delete-done' -- triggered at the end of a *Note `DELETE':
     delete. statement involving multiple tables.

The arguments for the statement probes are:

   * `query' -- the query string.

   * `status' -- the status of the query.  `0' for success, and `>0'
     for failure.

   * `rows' -- the number of rows affected by the statement. This
     returns the number rows found for *Note `SELECT': select, the
     number of rows deleted for *Note `DELETE': delete, and the number
     of rows successfully inserted for *Note `INSERT': insert.

   * `rowsmatched' -- the number of rows matched by the `WHERE' clause
     of an *Note `UPDATE': update. operation.

   * `rowschanged' -- the number of rows actually changed during an
     *Note `UPDATE': update. operation.

You use these probes to monitor the execution of these statement types
without having to monitor the user or client executing the statements.
A simple example of this is to track the execution times:

     #!/usr/sbin/dtrace -s

     #pragma D option quiet

     dtrace:::BEGIN
     {
        printf("%-60s %-8s %-8s %-8s\n", "Query", "RowsU", "RowsM", "Dur (ms)");
     }

     mysql*:::update-start, mysql*:::insert-start,
     mysql*:::delete-start, mysql*:::multi-delete-start,
     mysql*:::multi-delete-done, mysql*:::select-start,
     mysql*:::insert-select-start, mysql*:::multi-update-start
     {
         self->query = copyinstr(arg0);
         self->querystart = timestamp;
     }

     mysql*:::insert-done, mysql*:::select-done,
     mysql*:::delete-done, mysql*:::multi-delete-done, mysql*:::insert-select-done
     / self->querystart /
     {
         this->elapsed = ((timestamp - self->querystart)/1000000);
         printf("%-60s %-8d %-8d %d\n",
                self->query,
                0,
                arg1,
                this->elapsed);
         self->querystart = 0;
     }

     mysql*:::update-done, mysql*:::multi-update-done
     / self->querystart /
     {
         this->elapsed = ((timestamp - self->querystart)/1000000);
         printf("%-60s %-8d %-8d %d\n",
                self->query,
                arg1,
                arg2,
                this->elapsed);
         self->querystart = 0;
     }

When executed you can see the basic execution times and rows matches:

     Query                                                        RowsU    RowsM    Dur (ms)
     select * from t2                                             0        275      0
     insert into t2 (select * from t2)                            0        275      9
     update t2 set i=5 where i > 75                               110      110      8
     update t2 set i=5 where i < 25                               254      134      12
     delete from t2 where i < 5                                   0        0        0

Another alternative is to use the aggregation functions in DTrace to
aggregate the execution time of individual statements together:

     #!/usr/sbin/dtrace -s

     #pragma D option quiet

     mysql*:::update-start, mysql*:::insert-start,
     mysql*:::delete-start, mysql*:::multi-delete-start,
     mysql*:::multi-delete-done, mysql*:::select-start,
     mysql*:::insert-select-start, mysql*:::multi-update-start
     {
         self->querystart = timestamp;
     }

     mysql*:::select-done
     {
             @statements["select"] = sum(((timestamp - self->querystart)/1000000));
     }

     mysql*:::insert-done, mysql*:::insert-select-done
     {
             @statements["insert"] = sum(((timestamp - self->querystart)/1000000));
     }

     mysql*:::update-done, mysql*:::multi-update-done
     {
             @statements["update"] = sum(((timestamp - self->querystart)/1000000));
     }

     mysql*:::delete-done, mysql*:::multi-delete-done
     {
             @statements["delete"] = sum(((timestamp - self->querystart)/1000000));
     }

     tick-30s
     {
             printa(@statements);
     }

The above scipt aggregates the times spent doing each operation, which
could be used to help benchmark a standard suite of tests.

      delete                                                            0
       update                                                            0
       insert                                                           23
       select                                                         2484

       delete                                                            0
       update                                                            0
       insert                                                           39
       select                                                        10744

       delete                                                            0
       update                                                           26
       insert                                                           56
       select                                                        10944

       delete                                                            0
       update                                                           26
       insert                                                         2287
       select                                                        15985


File: manual.info,  Node: dba-dtrace-ref-network,  Prev: dba-dtrace-ref-statement,  Up: dba-dtrace-mysqld-ref

5.7.1.11 Network Probes
.......................

The network probes monitor the transfer of information from the MySQL
server and clients of all types over the network. The probes are
defined as follows:

     net-read-start()
     net-read-done(status, bytes)
     net-write-start(bytes)
     net-write-done(status)

   * `net-read-start' -- triggered when a network read operation is
     started.

   * `net-read-done' -- triggered when the network read operation
     completes. The `status' is an `integer' representing the return
     status for the operation, `0' for success and `1' for failure. The
     `bytes' argument is an integer specifying the number of bytes read
     during the process.

   * `net-start-bytes' -- triggered when data is written to a network
     socket. The single argument, `bytes', specifies the number of bytes
     written to the network socket.

   * `net-write-done' -- triggered when the the network write operation
     has completed. The single argument, `status', is an integer
     representing the return status for the operation, `0' for success
     and `1' for failure.

You can use the network probes to monitor the time spent reading from
and writing to network clients during execution. The following D script
provides an example of this. Both the cumlative time for the read or
write is calculated, and the number of bytes. Note that the dynamic
variable size has been increased (using the `dynvarsize' option) to
cope with the rapid firing of the individual probes for the network
reads/writes.

     #!/usr/sbin/dtrace -s

     #pragma D option quiet
     #pragma D option dynvarsize=4m

     dtrace:::BEGIN
     {
        printf("%-2s %-30s %-10s %9s %18s %-s \n",
               "St", "Who", "DB", "ConnID", "Dur microsec", "Query");
     }

     mysql*:::query-start
     {
        self->query = copyinstr(arg0);
        self->who   = strjoin(copyinstr(arg3),strjoin("@",copyinstr(arg4)));
        self->db    = copyinstr(arg2);
        self->connid = arg1;
        self->querystart = timestamp;
        self->netwrite = 0;
        self->netwritecum = 0;
        self->netwritebase = 0;
        self->netread = 0;
        self->netreadcum = 0;
        self->netreadbase = 0;
     }

     mysql*:::net-write-start
     {
        self->netwrite += arg0;
        self->netwritebase = timestamp;
     }

     mysql*:::net-write-done
     {
        self->netwritecum += (timestamp - self->netwritebase);
        self->netwritebase = 0;
     }

     mysql*:::net-read-start
     {
        self->netreadbase = timestamp;
     }

     mysql*:::net-read-done
     {
        self->netread += arg1;
        self->netreadcum += (timestamp - self->netreadbase);
        self->netreadbase = 0;
     }

     mysql*:::query-done
     {
        this->elapsed = (timestamp - self->querystart) /1000000;
        printf("%2d %-30s %-10s %9d %18d %s\n",
               arg0, self->who, self->db,
               self->connid, this->elapsed, self->query);
        printf("Net read: %d bytes (%d ms) write: %d bytes (%d ms)\n",
                    self->netread, (self->netreadcum/1000000),
                    self->netwrite, (self->netwritecum/1000000));
     }

When executing the above script on a machine with a remote client, you
can see that approximately a third of the time spent executing the
query is related to writing the query results back to the client.

     St Who                            DB            ConnID       Dur microsec Query
      0 root@::ffff:192.168.0.108      test              31               3495 select * from t1 limit 1000000
     Net read: 0 bytes (0 ms) write: 10000075 bytes (1220 ms)


File: manual.info,  Node: backup-and-recovery,  Next: optimization,  Prev: server-administration,  Up: Top

6 Backup and Recovery
*********************

* Menu:

* backup::                       Database Backups
* backup-strategy-example::      Example Backup and Recovery Strategy
* backup-database-restore::      Using MySQL Backup
* point-in-time-recovery::       Point-in-Time Recovery
* table-maintenance::            Table Maintenance and Crash Recovery

It is important to back up your databases in case problems occur so
that you can recover your data and be up and running again. MySQL
offers a variety of backup strategies from which you can choose to
select whatever methods best suit the requirements for your
installation.

Briefly summarized, backup concepts with which you should be familiar
include the following:

   * Logical versus physical backups

   * Online versus offline backups

   * Local versus remote backups

   * Snapshot backups

   * Full versus incremental backups

   * Point-in-time recovery

   * Backup scheduling, compression, and encryption

   * Table maintenance

     More generally, the following discussion amplifies on the
     properties of different backup methods.

   * *Logical versus physical (raw) backups.* Logical backups save
     information represented as logical database structure (*Note
     `CREATE DATABASE': create-database, *Note `CREATE TABLE':
     create-table.  statements) and content (*Note `INSERT': insert.
     statements or delimited-text files). Physical backups consist of
     raw copies of the directories and files that store database
     contents.

     Logical backup methods have these characteristics:

        * The backup is done by going through the MySQL server to
          obtain database structure and content information.

        * Backup is slower than physical methods because the server
          must access database information, convert it to logical
          format, and send it to the backup program.

        * Output is larger than for physical backup, particularly when
          saved in text format.

        * Backup and restore granularity is available at the server
          level (all databases), database level (all tables in a
          particular database), or table level. This is true regardless
          of storage engine.

        * The backup does not include log or configuration files, or
          other database-related files that are not part of databases.

        * Backups stored in logical format are machine independent and
          highly portable.

        * Logical backups are performed with the MySQL server running
          (the server is not taken offline).

        * Logical backup tools include the *Note `mysqldump':
          mysqldump. program and the *Note `SELECT ... INTO OUTFILE':
          select. statement. These work for any storage engine, even
          `MEMORY'.

          For restore, SQL-format dump files can be processed using the
          *Note `mysql': mysql. client. To load delimited-text files,
          use the *Note `LOAD DATA INFILE': load-data. statement or the
          *Note `mysqlimport': mysqlimport. client.

     Physical backup methods have these characteristics:

        * The backup consists of exact copies of database directories
          and files. Typically this is a copy of all or part of the
          MySQL data directory. Data from `MEMORY' tables cannot be
          backed up this way because their contents are not stored on
          disk.

        * Physical backup methods are faster than logical because they
          involve only file copying without conversion.

        * Output is more compact than for logical backup.

        * Backup and restore granularity extends from the level of the
          entire data directory down to the level of individual files.
          This may or may not provide for table-level granularity,
          depending on storage engine. (Each `MyISAM' table corresponds
          uniquely to a set of files, but an `InnoDB' table shares file
          storage with other `InnoDB' tables.)

        * In addition to databases, the backup can include any related
          files such as log or configuration files.

        * Backups are portable only to other machines that have
          identical or similar hardware characteristics.

        * Backups can be performed while the MySQL server is not
          running. If the server is running, it is necessary to perform
          appropriate locking so that the server does not change
          database contents during the backup.

        * Physical backup tools include file system-level commands
          (such as `cp', `scp', `tar', `rsync'), *Note `mysqlhotcopy':
          mysqlhotcopy. for `MyISAM' tables, `ibbackup' for `InnoDB'
          tables, or `START BACKUP' for `NDB' tables.

          For restore, files copied at the file system level or with
          *Note `mysqlhotcopy': mysqlhotcopy. can be copied back to
          their original locations with file system commands; `ibback'
          restores `InnoDB' tables, and `ndb_restore' restores `NDB'
          tables.

   * *Online versus offline backups.* Online backups take place while
     the MySQL server is running so that the database information can
     be obtained from the server.  Offline backups take place while the
     server is stopped. (This distinction can also be described as
     `hot' versus `cold' backups; a `warm' backup is one where the
     server remains running but locked against modifying data while you
     access database files externally.)

     Online backup methods have these characteristics:

        * Less intrusive to other clients, which can connect to the
          MySQL server during the backup and may be able to access data
          depending on what operations they need to perform.

        * Care must be taken to impose appropriate locking so that data
          modifications do not take place that compromise backup
          integrity.

     Offline backup methods have these characteristics:

        * Affects clients adversely because the server is unavailable
          during backup.

        * Simpler backup procedure because there is no possibility of
          interference from client activity.

   * *Local versus remote backups.* A local backup is performed on the
     same host where the MySQL server runs, whereas a remote backup is
     initiated from a different host.

        * *Note `mysqldump': mysqldump. can connect to local or remote
          servers. For SQL output (`CREATE' and *Note `INSERT': insert.
          statements), local or remote dumps can be done and generate
          output on the client.  For delimited-text output (with the
          `--tab' option), data files are created on the server host.

        * *Note `mysqlhotcopy': mysqlhotcopy. performs only local
          backups: It connects to the server to lock it against data
          modifications and then copies local table files.

        * *Note `SELECT ... INTO OUTFILE': select. can be initiated
          from a remote client host, but the output file is created on
          the server host.

        * Physical backup methods typically are initiated locally on
          the MySQL server host so that the server can be taken
          offline, although the destination for file copies might be
          remote.

   * *Snapshot backups.* Some file system implementations enable
     `snapshots' to be taken. These provide logical copies of the file
     system at a given point in time, without having to physically copy
     the entire file system. (For example, the implementation may use
     copy-on-write techniques so that only parts of the file system
     modified after the snapshot time need be copied.) MySQL itself
     does not provide the capability for taking file system snapshots.
     It is available through third-party solutions such as Veritas or
     LVM.

   * *Full versus incremental backups.* A full backup includes all data
     managed by a MySQL server at a given point in time. An incremental
     backup consists of the changes made to the data since the full
     backup.  MySQL has different ways to perform full backups, such as
     those described in previous items. Incremental backups are made
     possible by enabling the server's binary log, which the server
     uses to record data changes.

   * *Point-in-time recovery.* One use for the binary log is to achieve
     point-in-time recovery. This is done by recovering first from the
     backup files to restore the server to its state when the backup
     was made, and then by re-executing changes in subsequently written
     binary log files to redo data modifications up to the desired
     point in time.

   * *Backup scheduling, compression, and encryption.* Backup
     scheduling is valuable for automating backup procedures.
     Compression of backup output reduces space requirements, and
     encryption of the output provides better security against
     unauthorized access of backed-up data. MySQL itself does not
     provide these capabilities. `ibbackup' can compress `InnoDB'
     backups, and compression or encryption of backup output can be
     achieved using file system utilities.  Other third-party solutions
     may be available.

   * *Table maintenance.* Data integrity can be compromised if tables
     become corrupt. MySQL provides programs for checking tables and
     repairing them should problems be found. These programs apply
     primarily to `MyISAM' tables. See *Note table-maintenance::.

*Additional resources*

Resources related to backup or to maintaining data availability include
the following:

   * A forum dedicated to backup issues is available at
     `http://forums.mysql.com/list.php?93'.

   * The syntax of the SQL statements described here is given in *Note
     sql-syntax::.

   * Details for *Note `mysqldump': mysqldump, *Note `mysqlhotcopy':
     mysqlhotcopy, and other MySQL backup programs can be found in
     *Note programs::.

   * For additional information about `InnoDB' backup procedures, see
     *Note innodb-backup::.

   * Replication enables you to maintain identical data on multiple
     servers. This has several benefits, such as allowing client load
     to be distributed over servers, availability of data even if a
     given server is taken offline or fails, and the ability to make
     backups using a slave server without affecting the master. See
     *Note replication::.

   * MySQL Cluster provides a high-availability, high-redundancy
     version of MySQL adapted for the distributed computing
     environment. See MySQL Cluster NDB 6.X/7.X
     (http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html), which
     provides information about MySQL Cluster NDB 6.2 and 6.3 (based on
     MySQL 5.1 but containing the latest improvements and fixes for the
     `NDBCLUSTER' storage engine).

     *Note*:

     The `NDBCLUSTER' storage engine is currently not supported in
     MySQL 6.0.

   * Distributed Replicated Block Device (DRBD) is another
     high-availability solution. It works by replicating a block device
     from a primary server to a secondary server at the block level.
     See *Note ha-overview::


File: manual.info,  Node: backup,  Next: backup-strategy-example,  Prev: backup-and-recovery,  Up: backup-and-recovery

6.1 Database Backups
====================

This section summarizes some general methods for making backups.

*Making Backups by Copying Files*

`MyISAM' tables are stored as files, so it is easy to do a backup by
copying files. To get a consistent backup, do a *Note `LOCK TABLES':
lock-tables. on the relevant tables, followed by *Note `FLUSH TABLES':
flush. for the tables. See *Note lock-tables::, and *Note flush::. You
need only a read lock; this allows other clients to continue to query
the tables while you are making a copy of the files in the database
directory. The *Note `FLUSH TABLES': flush.  statement is needed to
ensure that the all active index pages are written to disk before you
start the backup.

*Making Delimited-Text File Backups*

To create a text file containing a table's data, you can use `SELECT *
INTO OUTFILE 'FILE_NAME' FROM TBL_NAME'. The file is created on the
MySQL server host, not the client host. For this statement, the output
file cannot already exist because allowing files to be overwritten
would constitute a security risk. See *Note select::. This method works
for any kind of data file, but saves only table data, not the table
structure.

To reload the output file, use *Note `LOAD DATA INFILE': load-data. or
*Note `mysqlimport': mysqlimport.

*Making Backups with *Note `mysqldump': mysqldump. or *Note
`mysqlhotcopy': mysqlhotcopy.*

Another technique for backing up a database is to use the *Note
`mysqldump': mysqldump. program or the *Note `mysqlhotcopy':
mysqlhotcopy. script.  *Note `mysqldump': mysqldump. is more general
because it can back up all kinds of tables. *Note `mysqlhotcopy':
mysqlhotcopy. works only with some storage engines. (See *Note
mysqldump::, and *Note mysqlhotcopy::.)

Create a full backup of your database:

     shell> mysqldump --tab=/PATH/TO/SOME/DIR --opt DB_NAME

Or:

     shell> mysqlhotcopy DB_NAME /PATH/TO/SOME/DIR

You can also create a binary backup simply by copying all table files
(`*.frm', `*.MYD', and `*.MYI' files), as long as the server isn't
updating anything. The *Note `mysqlhotcopy': mysqlhotcopy. script uses
this method. (But note that these methods do not work if your database
contains `InnoDB' tables.  `InnoDB' does not necessarily store table
contents in database directories, and *Note `mysqlhotcopy':
mysqlhotcopy. works only for `MyISAM' and `ISAM' tables.)

For `InnoDB' tables, it is possible to perform an online backup that
takes no locks on tables; see *Note mysqldump::.

*Using the Binary Log to Enable Incremental Backups*

MySQL supports incremental backups: You must start the server with the
`--log-bin' option to enable binary logging; see *Note binary-log::.
The binary log files provide you with the information you need to
replicate changes to the database that are made subsequent to the point
at which you performed a backup. At the moment you want to make an
incremental backup (containing all changes that happened since the last
full or incremental backup), you should rotate the binary log by using
*Note `FLUSH LOGS': flush. This done, you need to copy to the backup
location all binary logs which range from the one of the moment of the
last full or incremental backup to the last but one. These binary logs
are the incremental backup; at restore time, you apply them as
explained in *Note point-in-time-recovery::. The next time you do a
full backup, you should also rotate the binary log using *Note `FLUSH
LOGS': flush, *Note `mysqldump --flush-logs': mysqldump, or *Note
`mysqlhotcopy --flushlog': mysqlhotcopy. See *Note mysqldump::, and
*Note mysqlhotcopy::.

*Backing Up Replication Slaves*

If your MySQL server is a slave replication server, then regardless of
the backup method you choose, you should also back up the `master.info'
and `relay-log.info' files when you back up your slave's data. These
files are always needed to resume replication after you restore the
slave's data. If your slave is subject to replicating *Note `LOAD DATA
INFILE': load-data. commands, you should also back up any `SQL_LOAD-*'
files that may exist in the directory specified by the
`--slave-load-tmpdir' option. (This location defaults to the value of
the `tmpdir' system variable if not specified.) The slave needs these
files to resume replication of any interrupted *Note `LOAD DATA
INFILE': load-data. operations.

MySQL Enterprise

The MySQL Enterprise Monitor provides numerous advisors that issue
immediate warnings should replication issues arise. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

If you have performance problems with your master server while making
backups, one strategy that can help is to set up replication and
perform backups on the slave rather than on the master. See *Note
replication::.

*Recovering Corrupt Tables*

If you have to restore `MyISAM' tables that have become corrupt, try to
recover them using *Note `REPAIR TABLE': repair-table. or *Note
`myisamchk -r': myisamchk. first. That should work in 99.9% of all
cases. If *Note `myisamchk': myisamchk. fails, try the following
procedure.  It is assumed that you have enabled binary logging by
starting MySQL with the `--log-bin' option.

  1. Restore the original *Note `mysqldump': mysqldump. backup, or
     binary backup.

  2. Execute the following command to re-run the updates in the binary
     logs:

          shell> mysqlbinlog binlog.[0-9]* | mysql

     In some cases, you may want to re-run only certain binary logs,
     from certain positions (usually you want to re-run all binary logs
     from the date of the restored backup, excepting possibly some
     incorrect statements). See *Note point-in-time-recovery::.

*Making Backups Using a File System Snapshot*

If you are using a Veritas file system, you can make a backup like this:

  1. From a client program, execute *Note `FLUSH TABLES WITH READ
     LOCK': flush.

  2. From another shell, execute `mount vxfs snapshot'.

  3. From the first client, execute *Note `UNLOCK TABLES': lock-tables.

  4. Copy files from the snapshot.

  5. Unmount the snapshot.


File: manual.info,  Node: backup-strategy-example,  Next: backup-database-restore,  Prev: backup,  Up: backup-and-recovery

6.2 Example Backup and Recovery Strategy
========================================

* Menu:

* backup-policy::                Backup Policy
* recovery-from-backups::        Using Backups for Recovery
* backup-strategy-summary::      Backup Strategy Summary

This section discusses a procedure for performing backups that allows
you to recover data after several types of crashes:

   * Operating system crash

   * Power failure

   * File system crash

   * Hardware problem (hard drive, motherboard, and so forth)

The example commands do not include options such as `--user' and
`--password' for the *Note `mysqldump': mysqldump. and *Note `mysql':
mysql.  programs. You should include such options as necessary so that
the MySQL server allows you to connect to it.

We assume that data is stored in the `InnoDB' storage engine, which has
support for transactions and automatic crash recovery. We also assume
that the MySQL server is under load at the time of the crash. If it
were not, no recovery would ever be needed.

For cases of operating system crashes or power failures, we can assume
that MySQL's disk data is available after a restart. The `InnoDB' data
files might not contain consistent data due to the crash, but `InnoDB'
reads its logs and finds in them the list of pending committed and
non-committed transactions that have not been flushed to the data
files. `InnoDB' automatically rolls back those transactions that were
not committed, and flushes to its data files those that were committed.
Information about this recovery process is conveyed to the user through
the MySQL error log. The following is an example log excerpt:

     InnoDB: Database was not shut down normally.
     InnoDB: Starting recovery from log files...
     InnoDB: Starting log scan based on checkpoint at
     InnoDB: log sequence number 0 13674004
     InnoDB: Doing recovery: scanned up to log sequence number 0 13739520
     InnoDB: Doing recovery: scanned up to log sequence number 0 13805056
     InnoDB: Doing recovery: scanned up to log sequence number 0 13870592
     InnoDB: Doing recovery: scanned up to log sequence number 0 13936128
     ...
     InnoDB: Doing recovery: scanned up to log sequence number 0 20555264
     InnoDB: Doing recovery: scanned up to log sequence number 0 20620800
     InnoDB: Doing recovery: scanned up to log sequence number 0 20664692
     InnoDB: 1 uncommitted transaction(s) which must be rolled back
     InnoDB: Starting rollback of uncommitted transactions
     InnoDB: Rolling back trx no 16745
     InnoDB: Rolling back of trx no 16745 completed
     InnoDB: Rollback of uncommitted transactions completed
     InnoDB: Starting an apply batch of log records to the database...
     InnoDB: Apply batch completed
     InnoDB: Started
     mysqld: ready for connections

For the cases of file system crashes or hardware problems, we can
assume that the MySQL disk data is _not_ available after a restart.
This means that MySQL fails to start successfully because some blocks
of disk data are no longer readable. In this case, it is necessary to
reformat the disk, install a new one, or otherwise correct the
underlying problem.  Then it is necessary to recover our MySQL data
from backups, which means that we must already have made backups. To
make sure that is the case, we should design a backup policy.


File: manual.info,  Node: backup-policy,  Next: recovery-from-backups,  Prev: backup-strategy-example,  Up: backup-strategy-example

6.2.1 Backup Policy
-------------------

We all know that backups must be scheduled periodically. A full backup
(a snapshot of the data at a point in time) can be done in MySQL with
several tools. For example, `InnoDB Hot Backup' provides online
non-blocking physical backup of the `InnoDB' data files, and *Note
`mysqldump': mysqldump. provides online logical backup.  This
discussion uses *Note `mysqldump': mysqldump.

MySQL Enterprise

For expert advice on backups and replication, subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

Assume that we make a backup on Sunday at 1 p.m., when load is low. The
following command makes a full backup of all our `InnoDB' tables in all
databases:

     shell> mysqldump --single-transaction --all-databases > backup_sunday_1_PM.sql

This backup acquires a global read lock on all tables (using *Note
`FLUSH TABLES WITH READ LOCK': flush.) at the beginning of the dump. As
soon as this lock has been acquired, the binary log coordinates are
read and the lock is released. If long updating statements are running
when the *Note `FLUSH': flush. statement is issued, the MySQL server
may get stalled until those statements finish. After that, the dump
becomes lock-free and does not disturb reads and writes on the tables.

We assumed earlier that our tables are `InnoDB' tables, so
`--single-transaction' uses a consistent read and guarantees that data
seen by *Note `mysqldump': mysqldump. does not change. (Changes made by
other clients to `InnoDB' tables are not seen by the *Note `mysqldump':
mysqldump. process.) If we do also have other types of tables, we must
assume that they are not changed during the backup. For example, for the
`MyISAM' tables in the `mysql' database, we must assume that no
administrative changes are being made to MySQL accounts during the
backup.

The resulting `.sql' file produced by *Note `mysqldump': mysqldump.
contains a set of SQL *Note `INSERT': insert. statements that can be
used to reload the dumped tables at a later time.

Full backups are necessary, but they are not always convenient.  They
produce large backup files and take time to generate. They are not
optimal in the sense that each successive full backup includes all
data, even that part that has not changed since the previous full
backup. After we have made the initial full backup, it is more
efficient to make incremental backups. They are smaller and take less
time to produce. The tradeoff is that, at recovery time, you cannot
restore your data just by reloading the full backup. You must also
process the incremental backups to recover the incremental changes.

To make incremental backups, we need to save the incremental changes.
The MySQL server should always be started with the `--log-bin' option
so that it stores these changes in a file while it updates data. This
option enables binary logging, so that the server writes each SQL
statement that updates data into a file called a MySQL binary log.
Looking at the data directory of a MySQL server that was started with
the `--log-bin' option and that has been running for some days, we find
these MySQL binary log files:

     -rw-rw---- 1 guilhem  guilhem   1277324 Nov 10 23:59 gbichot2-bin.000001
     -rw-rw---- 1 guilhem  guilhem         4 Nov 10 23:59 gbichot2-bin.000002
     -rw-rw---- 1 guilhem  guilhem        79 Nov 11 11:06 gbichot2-bin.000003
     -rw-rw---- 1 guilhem  guilhem       508 Nov 11 11:08 gbichot2-bin.000004
     -rw-rw---- 1 guilhem  guilhem 220047446 Nov 12 16:47 gbichot2-bin.000005
     -rw-rw---- 1 guilhem  guilhem    998412 Nov 14 10:08 gbichot2-bin.000006
     -rw-rw---- 1 guilhem  guilhem       361 Nov 14 10:07 gbichot2-bin.index

Each time it restarts, the MySQL server creates a new binary log file
using the next number in the sequence. While the server is running, you
can also tell it to close the current binary log file and begin a new
one manually by issuing a *Note `FLUSH LOGS': flush. SQL statement or
with a *Note `mysqladmin flush-logs': mysqladmin.  command. *Note
`mysqldump': mysqldump. also has an option to flush the logs. The
`.index' file in the data directory contains the list of all MySQL
binary logs in the directory. This file is used for replication.

The MySQL binary logs are important for recovery because they form the
set of incremental backups. If you make sure to flush the logs when you
make your full backup, then any binary log files created afterward
contain all the data changes made since the backup. Let's modify the
previous *Note `mysqldump': mysqldump. command a bit so that it flushes
the MySQL binary logs at the moment of the full backup, and so that the
dump file contains the name of the new current binary log:

     shell> mysqldump --single-transaction --flush-logs --master-data=2 \
              --all-databases > backup_sunday_1_PM.sql

After executing this command, the data directory contains a new binary
log file, `gbichot2-bin.000007'. The resulting `.sql' file includes
these lines:

     -- Position to start replication or point-in-time recovery from
     -- CHANGE MASTER TO MASTER_LOG_FILE='gbichot2-bin.000007',MASTER_LOG_POS=4;

Because the *Note `mysqldump': mysqldump. command made a full backup,
those lines mean two things:

   * The `.sql' file contains all changes made before any changes
     written to the `gbichot2-bin.000007' binary log file or newer.

   * All data changes logged after the backup are not present in the
     `.sql', but are present in the `gbichot2-bin.000007' binary log
     file or newer.

On Monday at 1 p.m., we can create an incremental backup by flushing
the logs to begin a new binary log file. For example, executing a *Note
`mysqladmin flush-logs': mysqladmin. command creates
`gbichot2-bin.000008'. All changes between the Sunday 1 p.m. full
backup and Monday 1 p.m. will be in the `gbichot2-bin.000007' file. This
incremental backup is important, so it is a good idea to copy it to a
safe place. (For example, back it up on tape or DVD, or copy it to
another machine.) On Tuesday at 1 p.m., execute another *Note
`mysqladmin flush-logs': mysqladmin. command. All changes between
Monday 1 p.m. and Tuesday 1 p.m. will be in the `gbichot2-bin.000008'
file (which also should be copied somewhere safe).

The MySQL binary logs take up disk space. To free up space, purge them
from time to time. One way to do this is by deleting the binary logs
that are no longer needed, such as when we make a full backup:

     shell> mysqldump --single-transaction --flush-logs --master-data=2 \
              --all-databases --delete-master-logs > backup_sunday_1_PM.sql

*Note*:

Deleting the MySQL binary logs with *Note `mysqldump
--delete-master-logs': mysqldump. can be dangerous if your server is a
replication master server, because slave servers might not yet fully
have processed the contents of the binary log.  The description for the
*Note `PURGE BINARY LOGS': purge-binary-logs. statement explains what
should be verified before deleting the MySQL binary logs. See *Note
purge-binary-logs::.


File: manual.info,  Node: recovery-from-backups,  Next: backup-strategy-summary,  Prev: backup-policy,  Up: backup-strategy-example

6.2.2 Using Backups for Recovery
--------------------------------

Now, suppose that we have a catastrophic crash on Wednesday at 8 a.m.
that requires recovery from backups. To recover, first we restore the
last full backup we have (the one from Sunday 1 p.m.). The full backup
file is just a set of SQL statements, so restoring it is very easy:

     shell> mysql < backup_sunday_1_PM.sql

At this point, the data is restored to its state as of Sunday 1 p.m..
To restore the changes made since then, we must use the incremental
backups; that is, the `gbichot2-bin.000007' and `gbichot2-bin.000008'
binary log files. Fetch the files if necessary from where they were
backed up, and then process their contents like this:

     shell> mysqlbinlog gbichot2-bin.000007 gbichot2-bin.000008 | mysql

We now have recovered the data to its state as of Tuesday 1 p.m., but
still are missing the changes from that date to the date of the crash.
To not lose them, we would have needed to have the MySQL server store
its MySQL binary logs into a safe location (RAID disks, SAN, ...)
different from the place where it stores its data files, so that these
logs were not on the destroyed disk. (That is, we can start the server
with a `--log-bin' option that specifies a location on a different
physical device from the one on which the data directory resides. That
way, the logs are safe even if the device containing the directory is
lost.) If we had done this, we would have the `gbichot2-bin.000009'
file at hand, and we could apply it using *Note `mysqlbinlog':
mysqlbinlog. and *Note `mysql': mysql. to restore the most recent data
changes with no loss up to the moment of the crash.


File: manual.info,  Node: backup-strategy-summary,  Prev: recovery-from-backups,  Up: backup-strategy-example

6.2.3 Backup Strategy Summary
-----------------------------

In case of an operating system crash or power failure, `InnoDB' itself
does all the job of recovering data. But to make sure that you can
sleep well, observe the following guidelines:

   * Always run the MySQL server with the `--log-bin' option, or even
     `--log-bin=LOG_NAME', where the log file name is located on some
     safe media different from the drive on which the data directory is
     located. If you have such safe media, this technique can also be
     good for disk load balancing (which results in a performance
     improvement).

   * Make periodic full backups, using the *Note `mysqldump':
     mysqldump. command shown earlier in *Note backup-policy::, that
     makes an online, non-blocking backup.

   * Make periodic incremental backups by flushing the logs with *Note
     `FLUSH LOGS': flush.  or *Note `mysqladmin flush-logs': mysqladmin.


File: manual.info,  Node: backup-database-restore,  Next: point-in-time-recovery,  Prev: backup-strategy-example,  Up: backup-and-recovery

6.3 Using MySQL Backup
======================

* Menu:

* backup-database-restore-quick-guide::  Quick Guide to MySQL Backup
* backup-database-restore-implementation::  How MySQL Backup Works
* backup-database-restore-monitoring::  MySQL Backup Status Reporting and Monitoring

MySQL Backup is available as of MySQL 6.0.5. This feature comprises the
*Note `BACKUP DATABASE': backup-database. and *Note `RESTORE': restore.
statements. They provide a way to make a copy of a database or set of
databases at a given point in time, and a way to restore each database
to its state as of that time.

A backup operation can include tables for different storage engines and
the backup image will still be consistent. That is, you need not care
which storage engines you're using.  *Note `BACKUP DATABASE':
backup-database. saves the data in a consistent backup image with
respect to its `validity point.'

The validity point ties the backup to the binary log. Restoring a
backup can be combined with use of the binary log to accomplish
point-in-time recovery: If the restore operation is done because data
loss has occurred after the backup was made (that is, after the
validity point), restored databases can be brought up to the time of
data loss by executing the data changes in the binary log between the
times when the backup was made and when the data loss occurred.

A goal of the *Note `BACKUP DATABASE': backup-database. and *Note
`RESTORE': restore. statements is to enable other database operations
to proceed concurrently, to make it unnecessary to take databases
offline or prevent clients from accessing them. *Note `BACKUP
DATABASE': backup-database.  must block some operations from occurring
(such as dropping tables from a database while it is being backed up),
but the attempt is made to keep blocking to a minimum. Generally,
blocked operations are those involving Data Definition Language (DDL)
statements.  *Note `RESTORE': restore. must do more blocking because it
writes database contents rather than just reading them.

The following discussion covers these aspects of *Note `BACKUP
DATABASE': backup-database. and *Note `RESTORE': restore.:

   * Quick guide to making backups and restoring them

   * How *Note `BACKUP DATABASE': backup-database. and *Note `RESTORE':
     restore. work

   * Status reporting and monitoring for backup and restore operations

For additional information about the *Note `BACKUP DATABASE':
backup-database. and *Note `RESTORE': restore.  statements, see these
sections of the manual:

   * *Note backup-database::, and *Note restore::, describes the syntax
     for these statements.

   * Limitations on the use of these statements are discussed in *Note
     backup-database-restore-restrictions::.


File: manual.info,  Node: backup-database-restore-quick-guide,  Next: backup-database-restore-implementation,  Prev: backup-database-restore,  Up: backup-database-restore

6.3.1 Quick Guide to MySQL Backup
---------------------------------

Use the *Note `BACKUP DATABASE': backup-database. and *Note `RESTORE':
restore. statements like this:

   * *Note `BACKUP DATABASE': backup-database. backs up one or more
     databases to a named file:

          BACKUP DATABASE world TO '/tmp/mybackupfile';

     To back up more than one database, separate the names by commas:

          BACKUP DATABASE world, sakila TO '/tmp/mybackupfile';

     To select all databases for backup, use the `*' selector as a
     shortcut:

          BACKUP DATABASE * TO '/tmp/mybackupfile';

   * *Note `RESTORE': restore. restores databases using the contents of
     the backup file:

          RESTORE FROM '/tmp/mybackupfile';

*Note `BACKUP DATABASE': backup-database. backs up database and table
definitions, table data, stored routines, triggers, events, and views.
`TEMPORARY' tables are not included. Tablespace backup support is
limited to the `Falcon' storage engine.

Prior to MySQL 6.0.7, *Note `BACKUP DATABASE': backup-database. did not
save any privileges in the backup image file and *Note `RESTORE':
restore. did not restore privileges. As of MySQL 6.0.7, privileges are
saved and restored according to these rules:

   * *Note `BACKUP DATABASE': backup-database. saves privileges for the
     backed-up databases in the backup image file. The privileges are
     stored in the form of *Note `GRANT': grant. statements.

   * Only privileges are the database level or below (table, column,
     routine) are saved. Global privileges are not saved because they
     are not specific to the databases included in the backup.

   * Privileges that specify the database name using a pattern
     (containing the `'%'' or `'_'' wildcard character) are not saved
     because they might apply to databases not included in the backup.

   * For restore operations, only those privileges are restore that
     pertain to accounts that exist on the MySQL server performing the
     restore. Other privileges are ignored with a warning. (These
     warnings can be displayed with *Note `SHOW WARNINGS':
     show-warnings.) Suppose that a backup contains this *Note `GRANT':
     grant.  statement:

          GRANT SELECT, INSERT ON db1.* to 'someuser'@'localhost'

     The privileges specified by this statement will be restored if the
     `'someuser'@'localhost'' account exists, and ignored with a
     warning otherwise.

     Restoration of privileges for accounts that do not exist is not
     done because that would implicitly create accounts that have no
     password, which is a security risk.

Storage of *Note `GRANT': grant. statement in backup image files has a
security implication: Backup images should be stored in a secure
location so that unauthorized users cannot modify the *Note `GRANT':
grant.  statements contained therein to change the privileges granted by
restore operations.

For anything else not explicitly listed, assume that it is not backed
up. This includes but is not limited to items such as UDF definitions
and files, logs, and option files.

*Note `BACKUP DATABASE': backup-database. currently does not back up
the contents of the `mysql' database. This database contains the grant
tables that define user accounts and their privileges, as well as other
system information. To make a full server instance backup that includes
account information in addition to data, use the *Note `BACKUP
DATABASE': backup-database. statement together with the *Note
`mysqldump': mysqldump. program. In the following instructions, PATH
represents the full path name to the directory where you store your
backup files.

  1. Use *Note `mysqldump': mysqldump. to back up the `mysql' database.
     This is a blocking operation that prevents changes to the database
     during the dump, but the `mysql' database normally is relatively
     small and can be dumped quickly:

          shell> mysqldump --databases mysql > PATH/mysql-db.sql

  2. Use *Note `BACKUP DATABASE': backup-database. to back up the data
     from other databases. This is a non-blocking operation:

          mysql> BACKUP DATABASE * TO 'PATH/other-dbs.bak';

Restore the server instance later like this:

  1. To restore the user accounts, reload the `mysql' database dump
     file using the *Note `mysql': mysql. client:

          shell> mysql -u root -p < PATH/mysql-db.sql

  2. To restore the data for other databases, use *Note `RESTORE':
     restore. with the image file produced by *Note `BACKUP DATABASE':
     backup-database.:

          mysql> RESTORE FROM 'PATH/other-dbs.bak';

For more information about the operation of the *Note `BACKUP
DATABASE': backup-database. and *Note `RESTORE': restore. statements,
see *Note backup-database::, and *Note restore::.


File: manual.info,  Node: backup-database-restore-implementation,  Next: backup-database-restore-monitoring,  Prev: backup-database-restore-quick-guide,  Up: backup-database-restore

6.3.2 How MySQL Backup Works
----------------------------

A backup operation creates a backup of one or more databases at a given
point in time and saves it as a backup image, a file that contains the
backup data (table contents) and metadata (definitions for databases,
tables, and other objects, and server information).

The backup is intended to provide a consistent snapshot of the
backed-up data as of the point at which the operation began, and it is
intended to provide online operation as much as possible that allows
other server activity to proceed without blocking.

A backup operation begins at time T1 and ends at time T2, producing a
backup image that contains the backup state (database state) at time T,
where T1 < T < T2. The time T is called the validity point of the
backup image. It represents the time when all storage engines are
synchronized for the backup. Restoring this image restores the state to
be the same as it was at time T.

Consistency of the backup means that these constraints must be true:

   * Data from transactional tables is included only for committed
     transactions.

   * Data from non-transactional tables is included only for completed
     statements.

   * Referential integrity is maintained between all backed-up tables
     within a given backup image.

The referential-integrity constraint does not necessarily hold if two
tables are related but only one of them is included in a backup.
Restoring the backup then would restore only the backed-up table, which
can produce tables for which referential integrity no longer holds.

For a backup to proceed properly, certain types of server activity must
be blocked, so the backup system incorporates a commit blocker and a
Backup Metadata Lock.

The commit blocker has these properties:

   * Changes for non-transactional tables must be blocked.

   * Changes for transactional tables are not blocked, but only changes
     that have been committed when the backup occurs appear in the
     backup. Changes that occur during the backup operation are not
     included in the backup image.

When a backup or restore operation is in progress, it is not allowable
to modify the structure of database objects.  Consequently, during the
operation, the Backup Metadata Lock blocks statements that change
database metadata from executing.  A backup image stores metadata for
the following types of objects:

   * Databases

   * Tablespaces

   * Privileges

   * Tables

   * Views

   * Stored programs (functions, procedures, events, triggers)

This requires that the following metadata changes be frozen during
backup operation:

   * Databases being backed up should not disappear or be changed.

   * `BACKUP DATABASE * ...', new databases should not appear.

   * The list of objects inside each database should not change.

   * Metadata for objects in the databases should not change.

   * The set of privileges for each database should not change.

   * Users for which privileges are stored should not disappear or
     change.

   * Tablespaces used by tables being backed up should not disappear or
     change.

To achieve these requirements, the Backup Metadata Lock blocks the
following statements:

     DROP   DATABASE/TABLE/VIEW/FUNCTION/PROCEDURE/EVENT/TRIGGER/INDEX/
            USER/TABLESPACE
     CREATE DATABASE/TABLE/VIEW/FUNCTION/PROCEDURE/EVENT/TRIGGER/INDEX
     ALTER  DATABASE/TABLE/VIEW/FUNCTION/PROCEDURE/EVENT/TABLESPACE
     RENAME TABLE/USER
     GRANT/REVOKE
     TRUNCATE/OPTIMIZE/REPAIR TABLE

Currently, all instances of statements that change metadata are
blocked, even for database or table objects that are not included in
the backup. Eventually, the goal is to block only metadata-changing
statements for objects in the backup.

Blocking works in both directions. A backup or restore blocks DDL
statements, but if a backup or restore operation is initiated while DDL
statements are in progress, the operation waits until the statements
have finished.

Implementation of *Note `BACKUP DATABASE': backup-database.  and *Note
`RESTORE': restore. uses an architecture with the following design:

   * The MySQL server communicates with the backup kernel.

   * The backup kernel is responsible for communicating with backup
     engines and for handling metadata (definitions for databases,
     tables, and other objects, as well as server information).

   * Each backup engine provides backup and restore drivers for the
     backup kernel to use.

   * An engine's backup and restore drivers perform actual transfer of
     data (table contents).

The backup system chooses from among the backup engines available to it:

   * There is a default backup engine to be used if a better one is not
     found. This engine provides default backup and restore drivers
     that use a blocking algorithm. For example, the backup driver
     locks all tables at the start of the backup and unlocks them after
     the last one is processed (which may occur before the operation is
     complete).

   * A consistent-snapshot engine implements the same kind of backup as
     that made by *Note `mysqldump --single-transaction': mysqldump.

     The backup driver for the snapshot engine works with only those
     storage engines that support consistent read via the handler
     interface, which currently includes only `InnoDB' and `Falcon'. The
     backup driver creates a logical backup because it reads rows one
     at a time and returns them to the backup kernel to be stored in
     the backup image.

A backup image must have contents that are consistent with the binary
log coordinates taken from the time of the backup.  Otherwise,
point-in-time recovery using the backup image plus the binary log
contents will not work correctly.  *Note `BACKUP DATABASE':
backup-database. synchronizes with binary logging to make sure that the
backup image and binary log are consistent with each other. This way,
if data loss occurs later, use of the backup image combined with the
binary log makes makes point-in-time recovery possible:

  1. Restore the backup image

  2. Re-execute binary log contents beginning from the coordinates of
     the backup's validity point up to the desired point of recovery


File: manual.info,  Node: backup-database-restore-monitoring,  Prev: backup-database-restore-implementation,  Up: backup-database-restore

6.3.3 MySQL Backup Status Reporting and Monitoring
--------------------------------------------------

* Menu:

* backup-database-restore-log-control::  MySQL Backup Log Control
* backup-database-restore-log-contents::  MySQL Backup Log Contents

MySQL provides information about the status or progress of *Note
`BACKUP DATABASE': backup-database. or *Note `RESTORE': restore.
operations in the following ways:

   * *Note `SHOW PROCESSLIST': show-processlist. displays information
     while a thread performing a backup or restore is executing.

   * Upon successful completion, the *Note `BACKUP DATABASE':
     backup-database. and *Note `RESTORE': restore. statements return a
     result set with the backup number. (This number is the ID for the
     corresponding row or rows in the metadata tables described later.)
     Warnings produced during the operation can be displayed with *Note
     `SHOW WARNINGS': show-warnings.

     If errors occur during a backup or restore operation, they are
     written to the error log, recorded in the progress tables, and are
     available via the *Note `SHOW ERRORS': show-errors. and *Note
     `SHOW WARNINGS': show-warnings. statements.

     If a fatal error occurs, the *Note `BACKUP DATABASE':
     backup-database. or *Note `RESTORE': restore.  statement reports
     it to the user.

   * The server maintains `backup_history' and `backup_progress' tables
     in the `mysql' database that contain metadata indicating backup
     status and progress. It is also possible to write log information
     to files. For information about selecting log destinations, see
     *Note backup-database-restore-log-control::. For a description of
     what is logged, see *Note backup-database-restore-log-contents::.

     If you upgrade to MySQL 6.0.5 or later from an older version, be
     sure to run *Note `mysql_upgrade': mysql-upgrade. to ensure that
     the backup log tables tables exist. From MySQL 6.0.5 through
     6.0.7, these tables were named `online_backup' and
     `online_backup_progress'.

     Currently, there are no `INFORMATION_SCHEMA' tables corresponding
     to the `backup_history' and `backup_progress' tables.


File: manual.info,  Node: backup-database-restore-log-control,  Next: backup-database-restore-log-contents,  Prev: backup-database-restore-monitoring,  Up: backup-database-restore-monitoring

6.3.3.1 MySQL Backup Log Control
................................

MySQL Backup provides status and progress logging. This capability can
be enabled or disabled. If logging is enabled, tables in the `mysql'
database or log files can be used as the destinations for log output.
These features are similar to those provided for the general query log
and slow query log (see *Note log-tables::), although the options and
variables are different.

This section describes how to control MySQL Backup logging.  For a
description of what is logged, see *Note
backup-database-restore-log-contents::.

*Note*:

The features described here are available as of MySQL 6.0.8.  Before
6.0.8, MySQL Backup logs to the `online_backup' and
`online_backup_progress' tables in the `mysql' database. Logging to
files is not supported and logging cannot be disabled.

*Log control at server startup.* The `--log-backup-output' option
specifies the destination for log output, if logging is enabled, but
the option does not in itself enable the logs.  The syntax for this
option is `--log-backup-output[=VALUE,...]':

   * If `--log-backup-output' is given with a value, the value can be a
     comma-separated list of one or more of the words `TABLE' (log to
     tables), `FILE' (log to files), or `NONE' (do not log to tables or
     files). `NONE', if present, takes precedence over any other
     specifiers.

   * If `--log-backup-output' is omitted or given without a value, the
     default is `TABLE'.

The `--backup_history_log' and `--backup_progress_log' options, if
given, enable logging to the history and progress logs for the selected
log destinations. (By default, both logs are enabled.) These options
take an optional argument of 1 or 0 to enable or disable the log. If
either log is enabled, the server opens the corresponding log file and
writes startup messages to it. However, logging to the file does not
occur unless the `FILE' log destination is selected.

Examples:

   * With no logging arguments, MySQL Backup logs to the log tables by
     default.

   * To write log entries to the log tables and log files, use
     `--log-backup-output=TABLE,FILE' to select both log destinations.

*Log control at runtime.* Several system variables are associated with
log tables and files and enable runtime control over logging:

   * The global `log_backup_output' system variable indicates the
     current logging destination. It can be modified at runtime to
     change the destination.

   * The global `backup_history_log' and `backup_progress_log'
     variables indicate whether the history and progress logs are
     enabled (`ON') or disabled (`OFF'). You can set these variables at
     runtime to control whether the logs are enabled.

   * The global `backup_history_log_file' and
     `backup_progress_log_file' variables indicate the names of the
     history and progress log files.  You can set these variables at
     server startup or at runtime to change the names of the log files.


File: manual.info,  Node: backup-database-restore-log-contents,  Prev: backup-database-restore-log-control,  Up: backup-database-restore-monitoring

6.3.3.2 MySQL Backup Log Contents
.................................

If you enable backup logging to tables, MySQL Backup uses the
`backup_history' and `backup_progress' tables in the `mysql' database.
For logging to files, MySQL Backup uses the `backup_history.log' and
`backup_progress.log' files in the MySQL data directory by default. The
log file names can be changed by setting the global
`backup_history_log_file' and `backup_progress_log_file' system
variables. For information about selecting log destinations, see *Note
backup-database-restore-log-control::.

The contents of the log tables are discussed following. For logging to
files, the server writes lines with a field for each column in the
corresponding log table. The server also writes an initial line to the
file at startup to indicate the names of the fields. Backup log
contents can be culled with the *Note `PURGE BACKUP LOGS':
purge-backup-logs.  statement. See *Note purge-backup-logs::.

If the table destination is selected for backup logging, the server
uses these tables:

   * The `backup_history' table contains a row for each backup and
     restore operation. A row is created when an operation completes.
     The rows in this table serve as a history of all backup and
     restore operations performed on the server. The table can be
     queried to obtained detailed information about the operations or
     as a means to create a summary of the operations. The rows are not
     removed from the table by the server. Any table maintenance, such
     as removing old rows, is intended to be performed by the database
     administrator.

   * The `backup_progress' table contains progress data describing the
     steps in the most recent backup or restore operation. There may be
     multiple rows for the operation. Rows are added to this table over
     the course of the operation and are not updated. This enables the
     table to be used to track the current progress of the operation.
     Each row in the table represents a step in the operation and may
     contain informational statements, errors, and other pertinent
     information. The data in this table has a limited lifetime. At the
     start of each operation, the table is truncated and new data is
     added.  The database administrator should not need to perform
     maintenance for this data.

The `backup_history' table has this structure:

     CREATE TABLE backup_history (
         backup_id           BIGINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
         process_id          INT UNSIGNED NOT NULL,
         binlog_pos          INT UNSIGNED DEFAULT 0,
         binlog_file         CHAR(64),
         backup_state        ENUM('complete', 'starting', 'validity point',
                                  'running', 'error', 'cancel') NOT NULL,
         operation           ENUM('backup', 'restore') NOT NULL,
         error_num           INT NOT NULL DEFAULT 0,
         num_objects         INT UNSIGNED NOT NULL DEFAULT 0,
         total_bytes         BIGINT UNSIGNED,
         validity_point_time DATETIME,
         start_time          DATETIME,
         stop_time           DATETIME,
         host_or_server_name CHAR (30),
         username            CHAR (30),
         backup_file         CHAR (100),
         backup_file_path    VARCHAR (512),
         user_comment        VARCHAR (200),
         command             VARCHAR (512),
         engines             VARCHAR (100),
     ) ENGINE=CSV CHARSET=utf8;

The `backup_history' columns are used as follows:

   * `backup_id'

     The ID for the table row. *Note `BACKUP DATABASE':
     backup-database. and *Note `RESTORE': restore. return a result set
     containing a backup ID, which is the value that tells you which
     row in the `backup_history' table corresponds to the backup or
     restore operation.

   * `process_id'

     The process ID that the operation ran as.

   * `binlog_pos', `binlog_file'

     For a backup, the binary log position and file name at the time
     the validity point is generated (the time when all storage engines
     are synchronized). Before that time, the values are 0 and `NULL'.

   * `backup_state'

     The status of the operation.

   * `operation'

     The type of operation.

   * `error_num'

     The error from this operation (0 = no error).

   * `num_objects'

     The number of objects in the backup.

   * `total_bytes'

     The size of the backup image file in bytes.

   * `validity_point_time'

     For a backup, this is the time that the validity point was
     generated. Before that time, the value is `NULL'. For a restore,
     the value currently is always `NULL'.

   * `start_time', `stop_time'

     The date and time when the operation started and stopped.

   * `host_or_server_name'

     The server name where the operation ran.

   * `username'

     The name of the user who ran the operation.

   * `backup_file'

     The name of the backup image file. As of MySQL 6.0.8, this column
     contains the file basename.

   * `backup_file_path'

     The directory containing the image file. This column was added in
     MySQL 6.0.8.

   * `user_comment'

     The comment from the user entered at the command line.

   * `command'

     The statement used to perform the operation.

   * `drivers'

     The names of the drivers used in the operation. Before MySQL
     6.0.7, this column was named `engines'.

The `backup_progress' table has this structure:

     CREATE TABLE backup_progress (
         backup_id   BIGINT UNSIGNED NOT NULL
         object      CHAR (30) NOT NULL
         start_time  DATATIME
         stop_time   DATATIME
         total_bytes BIGINT
         progress    BIGINT UNSIGNED
         error_num   INT NOT NULL DEFAULT 0
         notes       CHAR(100)
     ) ENGINE=CSV CHARSET=utf8;

The `backup_progress' columns are used as follows:

   * `backup_id'

     The `backup_id' value of the `backup_history' table row with which
     the rows in the `backup_progress' table are associated.

   * `object'

     The object being operated on.

   * `start_time', `stop_time'

     The date and time when the operation started and stopped.

   * `total_bytes'

     The size of the object in bytes.

   * `progress'

     The number of bytes processed.

   * `error_num'

     The error from this operation (0 = no error).

   * `notes'

     Commentary from the backup engine.


File: manual.info,  Node: point-in-time-recovery,  Next: table-maintenance,  Prev: backup-database-restore,  Up: backup-and-recovery

6.4 Point-in-Time Recovery
==========================

* Menu:

* point-in-time-recovery-times::  Specifying Times for Recovery
* point-in-time-recovery-positions::  Specifying Positions for Recovery

If a MySQL server was started with the `--log-bin' option to enable
binary logging, you can use the *Note `mysqlbinlog': mysqlbinlog.
utility to recover data from the binary log files, starting from a
specified point in time (for example, since your last backup) until the
present or another specified point in time. For information on enabling
the binary log and using *Note `mysqlbinlog': mysqlbinlog, see *Note
binary-log::, and *Note mysqlbinlog::.

MySQL Enterprise

For maximum data recovery, the MySQL Enterprise Monitor advises
subscribers to synchronize to disk at each write. For more information,
see `http://www.mysql.com/products/enterprise/advisors.html'.

To restore data from a binary log, you must know the location and name
of the current binary log file. By default, the server creates binary
log files in the data directory, but a path name can be specified with
the `--log-bin' option to place the files in a different location.
Typically the option is given in an option file (that is, `my.cnf' or
`my.ini', depending on your system). It can also be given on the command
line when the server is started. To determine the name of the current
binary log file, issue the following statement:

     mysql> SHOW MASTER STATUS

If you prefer, you can execute the following command from the command
line instead:

     shell> mysql -u root -p -E -e "SHOW MASTER STATUS"

Enter the `root' password for your server when *Note `mysql': mysql.
prompts you for it.

To view the contents of a binary log, use `mysqlbinlog'. See *Note
mysqlbinlog::.


File: manual.info,  Node: point-in-time-recovery-times,  Next: point-in-time-recovery-positions,  Prev: point-in-time-recovery,  Up: point-in-time-recovery

6.4.1 Specifying Times for Recovery
-----------------------------------

To indicate the start and end times for recovery, specify the
`--start-datetime' and `--stop-datetime' options for *Note
`mysqlbinlog': mysqlbinlog, in *Note `DATETIME': datetime. format. As
an example, suppose that exactly at 10:00 a.m. on April 20, 2005 an SQL
statement was executed that deleted a large table. To restore the table
and data, you could restore the previous night's backup, and then
execute the following command:

     shell> mysqlbinlog --stop-datetime="2005-04-20 9:59:59" \
              /var/log/mysql/bin.123456 | mysql -u root -p

This command recovers all of the data up until the date and time given
by the `--stop-datetime' option. If you did not detect the erroneous
SQL statement that was entered until hours later, you will probably
also want to recover the activity that occurred afterward. Based on
this, you could run *Note `mysqlbinlog': mysqlbinlog. again with a
start date and time, like so:

     shell> mysqlbinlog --start-datetime="2005-04-20 10:01:00" \
              /var/log/mysql/bin.123456 | mysql -u root -p

In this command, the SQL statements logged from 10:01 a.m. on will be
re-executed. The combination of restoring of the previous night's dump
file and the two *Note `mysqlbinlog': mysqlbinlog. commands restores
everything up until one second before 10:00 a.m. and everything from
10:01 a.m. on. You should examine the log to be sure of the exact times
to specify for the commands. To display the log file contents without
executing them, use this command:

     shell> mysqlbinlog /var/log/mysql/bin.123456 > /tmp/mysql_restore.sql

Then open the file with a text editor to examine it.


File: manual.info,  Node: point-in-time-recovery-positions,  Prev: point-in-time-recovery-times,  Up: point-in-time-recovery

6.4.2 Specifying Positions for Recovery
---------------------------------------

Instead of specifying dates and times, the `--start-position' and
`--stop-position' options for *Note `mysqlbinlog': mysqlbinlog. can be
used for specifying log positions. They work the same as the start and
stop date options, except that you specify log position numbers rather
than dates. Using positions may enable you to be more precise about
which part of the log to recover, especially if many transactions
occurred around the same time as a damaging SQL statement. To determine
the position numbers, run *Note `mysqlbinlog': mysqlbinlog. for a range
of times near the time when the unwanted transaction was executed, but
redirect the results to a text file for examination. This can be done
like so:

     shell> mysqlbinlog --start-datetime="2005-04-20 9:55:00" \
              --stop-datetime="2005-04-20 10:05:00" \
              /var/log/mysql/bin.123456 > /tmp/mysql_restore.sql

This command creates a small text file in the `/tmp' directory that
contains the SQL statements around the time that the deleterious SQL
statement was executed. Open this file with a text editor and look for
the statement that you don't want to repeat. Determine the positions in
the binary log for stopping and resuming the recovery and make note of
them. Positions are labeled as `log_pos' followed by a number. After
restoring the previous backup file, use the position numbers to process
the binary log file. For example, you would use commands something like
these:

     shell> mysqlbinlog --stop-position="368312" /var/log/mysql/bin.123456 \
              | mysql -u root -p

     shell> mysqlbinlog --start-position="368315" /var/log/mysql/bin.123456 \
              | mysql -u root -p

The first command recovers all the transactions up until the stop
position given. The second command recovers all transactions from the
starting position given until the end of the binary log. Because the
output of *Note `mysqlbinlog': mysqlbinlog. includes `SET TIMESTAMP'
statements before each SQL statement recorded, the recovered data and
related MySQL logs will reflect the original times at which the
transactions were executed.


File: manual.info,  Node: table-maintenance,  Prev: point-in-time-recovery,  Up: backup-and-recovery

6.5 Table Maintenance and Crash Recovery
========================================

* Menu:

* crash-recovery::               Using `myisamchk' for Crash Recovery
* check::                        How to Check `MyISAM' Tables for Errors
* repair::                       How to Repair Tables
* table-optimization::           Table Optimization
* table-info::                   Getting Information About a Table
* maintenance-schedule::         Setting Up a Table Maintenance Schedule

This section discusses how to use *Note `myisamchk': myisamchk. to
check or repair `MyISAM' tables (tables that have `.MYD' and `.MYI'
files for storing data and indexes). For general *Note `myisamchk':
myisamchk. background, see *Note myisamchk::.

You can use *Note `myisamchk': myisamchk. to get information about your
database tables or to check, repair, or optimize them. The following
sections describe how to perform these operations and how to set up a
table maintenance schedule.

Even though table repair with *Note `myisamchk': myisamchk. is quite
secure, it is always a good idea to make a backup _before_ doing a
repair or any maintenance operation that could make a lot of changes to
a table.

*Note `myisamchk': myisamchk. operations that affect indexes can cause
`FULLTEXT' indexes to be rebuilt with full-text parameters that are
incompatible with the values used by the MySQL server. To avoid this
problem, follow the guidelines in *Note myisamchk-general-options::.

In many cases, you may find it simpler to do `MyISAM' table maintenance
using the SQL statements that perform operations that *Note
`myisamchk': myisamchk. can do:

   * To check or repair `MyISAM' tables, use *Note `CHECK TABLE':
     check-table. or *Note `REPAIR TABLE': repair-table.

   * To optimize `MyISAM' tables, use *Note `OPTIMIZE TABLE':
     optimize-table.

   * To analyze `MyISAM' tables, use *Note `ANALYZE TABLE':
     analyze-table.

These statements can be used directly or by means of the *Note
`mysqlcheck': mysqlcheck. client program. One advantage of these
statements over *Note `myisamchk': myisamchk. is that the server does
all the work. With *Note `myisamchk': myisamchk, you must make sure
that the server does not use the tables at the same time so that there
is no unwanted interaction between *Note `myisamchk': myisamchk. and
the server. See *Note analyze-table::, *Note check-table::, *Note
optimize-table::, and *Note repair-table::.


File: manual.info,  Node: crash-recovery,  Next: check,  Prev: table-maintenance,  Up: table-maintenance

6.5.1 Using `myisamchk' for Crash Recovery
------------------------------------------

This section describes how to check for and deal with data corruption
in MySQL databases. If your tables become corrupted frequently, you
should try to find the reason why. See *Note crashing::.

For an explanation of how `MyISAM' tables can become corrupted, see
*Note myisam-table-problems::.

If you run *Note `mysqld': mysqld. with external locking disabled
(which is the default as of MySQL 4.0), you cannot reliably use *Note
`myisamchk': myisamchk. to check a table when *Note `mysqld': mysqld.
is using the same table. If you can be certain that no one will access
the tables through *Note `mysqld': mysqld. while you run *Note
`myisamchk': myisamchk, you only have to execute *Note `mysqladmin
flush-tables': mysqladmin. before you start checking the tables. If you
cannot guarantee this, you must stop *Note `mysqld': mysqld. while you
check the tables. If you run *Note `myisamchk': myisamchk. to check
tables that *Note `mysqld': mysqld. is updating at the same time, you
may get a warning that a table is corrupt even when it is not.

If the server is run with external locking enabled, you can use *Note
`myisamchk': myisamchk. to check tables at any time. In this case, if
the server tries to update a table that *Note `myisamchk': myisamchk.
is using, the server will wait for *Note `myisamchk': myisamchk. to
finish before it continues.

If you use *Note `myisamchk': myisamchk. to repair or optimize tables,
you _must_ always ensure that the *Note `mysqld': mysqld. server is not
using the table (this also applies if external locking is disabled). If
you don't stop *Note `mysqld': mysqld, you should at least do a *Note
`mysqladmin flush-tables': mysqladmin. before you run *Note
`myisamchk': myisamchk. Your tables _may become corrupted_ if the
server and *Note `myisamchk': myisamchk. access the tables
simultaneously.

When performing crash recovery, it is important to understand that each
`MyISAM' table TBL_NAME in a database corresponds to the three files in
the database directory shown in the following table.

*File*         *Purpose*
`TBL_NAME.frm' Definition (format) file
`TBL_NAME.MYD' Data file
`TBL_NAME.MYI' Index file

Each of these three file types is subject to corruption in various
ways, but problems occur most often in data files and index files.

*Note `myisamchk': myisamchk. works by creating a copy of the `.MYD'
data file row by row. It ends the repair stage by removing the old
`.MYD' file and renaming the new file to the original file name. If you
use `--quick', *Note `myisamchk': myisamchk. does not create a temporary
`.MYD' file, but instead assumes that the `.MYD' file is correct and
generates only a new index file without touching the `.MYD' file. This
is safe, because *Note `myisamchk': myisamchk.  automatically detects
whether the `.MYD' file is corrupt and aborts the repair if it is. You
can also specify the `--quick' option twice to *Note `myisamchk':
myisamchk. In this case, *Note `myisamchk': myisamchk. does not abort
on some errors (such as duplicate-key errors) but instead tries to
resolve them by modifying the `.MYD' file. Normally the use of two
`--quick' options is useful only if you have too little free disk space
to perform a normal repair. In this case, you should at least make a
backup of the table before running *Note `myisamchk': myisamchk.


File: manual.info,  Node: check,  Next: repair,  Prev: crash-recovery,  Up: table-maintenance

6.5.2 How to Check `MyISAM' Tables for Errors
---------------------------------------------

To check a `MyISAM' table, use the following commands:

   * `myisamchk TBL_NAME'

     This finds 99.99% of all errors. What it cannot find is corruption
     that involves _only_ the data file (which is very unusual). If you
     want to check a table, you should normally run *Note `myisamchk':
     myisamchk. without options or with the `-s' (silent) option.

   * `myisamchk -m TBL_NAME'

     This finds 99.999% of all errors. It first checks all index
     entries for errors and then reads through all rows. It calculates
     a checksum for all key values in the rows and verifies that the
     checksum matches the checksum for the keys in the index tree.

   * `myisamchk -e TBL_NAME'

     This does a complete and thorough check of all data (`-e' means
     `extended check').  It does a check-read of every key for each row
     to verify that they indeed point to the correct row. This may take
     a long time for a large table that has many indexes. Normally,
     *Note `myisamchk': myisamchk. stops after the first error it
     finds. If you want to obtain more information, you can add the
     `-v' (verbose) option. This causes *Note `myisamchk': myisamchk.
     to keep going, up through a maximum of 20 errors.

   * `myisamchk -e -i TBL_NAME'

     This is like the previous command, but the `-i' option tells *Note
     `myisamchk': myisamchk. to print additional statistical
     information.

In most cases, a simple *Note `myisamchk': myisamchk. command with no
arguments other than the table name is sufficient to check a table.


File: manual.info,  Node: repair,  Next: table-optimization,  Prev: check,  Up: table-maintenance

6.5.3 How to Repair Tables
--------------------------

The discussion in this section describes how to use *Note `myisamchk':
myisamchk. on `MyISAM' tables (extensions `.MYI' and `.MYD').

You can also (and should, if possible) use the *Note `CHECK TABLE':
check-table. and *Note `REPAIR TABLE': repair-table. statements to check
and repair `MyISAM' tables. See *Note check-table::, and *Note
repair-table::.

Symptoms of corrupted tables include queries that abort unexpectedly
and observable errors such as these:

   * `TBL_NAME.frm' is locked against change

   * Can't find file `TBL_NAME.MYI' (Errcode: NNN)

   * Unexpected end of file

   * Record file is crashed

   * Got error NNN from table handler

To get more information about the error, run *Note `perror': perror.
NNN, where NNN is the error number. The following example shows how to
use *Note `perror': perror. to find the meanings for the most common
error numbers that indicate a problem with a table:

     shell> perror 126 127 132 134 135 136 141 144 145
     MySQL error code 126 = Index file is crashed
     MySQL error code 127 = Record-file is crashed
     MySQL error code 132 = Old database file
     MySQL error code 134 = Record was already deleted (or record file crashed)
     MySQL error code 135 = No more room in record file
     MySQL error code 136 = No more room in index file
     MySQL error code 141 = Duplicate unique key or constraint on write or update
     MySQL error code 144 = Table is crashed and last repair failed
     MySQL error code 145 = Table was marked as crashed and should be repaired

Note that error 135 (no more room in record file) and error 136 (no
more room in index file) are not errors that can be fixed by a simple
repair. In this case, you must use *Note `ALTER TABLE': alter-table. to
increase the `MAX_ROWS' and `AVG_ROW_LENGTH' table option values:

     ALTER TABLE TBL_NAME MAX_ROWS=XXX AVG_ROW_LENGTH=YYY;

If you do not know the current table option values, use *Note `SHOW
CREATE TABLE': show-create-table.

For the other errors, you must repair your tables.  *Note `myisamchk':
myisamchk. can usually detect and fix most problems that occur.

The repair process involves up to four stages, described here.  Before
you begin, you should change location to the database directory and
check the permissions of the table files. On Unix, make sure that they
are readable by the user that *Note `mysqld': mysqld. runs as (and to
you, because you need to access the files you are checking). If it
turns out you need to modify files, they must also be writable by you.

This section is for the cases where a table check fails (such as those
described in *Note check::), or you want to use the extended features
that *Note `myisamchk': myisamchk.  provides.

The options that you can use for table maintenance with *Note
`myisamchk': myisamchk. are described in *Note myisamchk::.

If you are going to repair a table from the command line, you must
first stop the *Note `mysqld': mysqld. server. Note that when you do
*Note `mysqladmin shutdown': mysqladmin. on a remote server, the *Note
`mysqld': mysqld. server is still alive for a while after *Note
`mysqladmin': mysqladmin. returns, until all statement-processing has
stopped and all index changes have been flushed to disk.

*Stage 1: Checking your tables*

Run *Note `myisamchk *.MYI': myisamchk. or *Note `myisamchk -e *.MYI':
myisamchk. if you have more time. Use the `-s' (silent) option to
suppress unnecessary information.

If the *Note `mysqld': mysqld. server is stopped, you should use the
`--update-state' option to tell *Note `myisamchk': myisamchk. to mark
the table as `checked.'

You have to repair only those tables for which *Note `myisamchk':
myisamchk. announces an error. For such tables, proceed to Stage 2.

If you get unexpected errors when checking (such as `out of memory'
errors), or if *Note `myisamchk': myisamchk.  crashes, go to Stage 3.

*Stage 2: Easy safe repair*

First, try *Note `myisamchk -r -q TBL_NAME': myisamchk. (`-r -q' means
`quick recovery mode'). This attempts to repair the index file without
touching the data file. If the data file contains everything that it
should and the delete links point at the correct locations within the
data file, this should work, and the table is fixed. Start repairing
the next table. Otherwise, use the following procedure:

  1. Make a backup of the data file before continuing.

  2. Use *Note `myisamchk -r TBL_NAME': myisamchk.  (`-r' means
     `recovery mode').  This removes incorrect rows and deleted rows
     from the data file and reconstructs the index file.

  3. If the preceding step fails, use *Note `myisamchk --safe-recover
     TBL_NAME': myisamchk. Safe recovery mode uses an old recovery
     method that handles a few cases that regular recovery mode does
     not (but is slower).

*Note*:

If you want a repair operation to go much faster, you should set the
values of the `sort_buffer_size' and `key_buffer_size' variables each
to about 25% of your available memory when running *Note `myisamchk':
myisamchk.

If you get unexpected errors when repairing (such as `out of memory'
errors), or if *Note `myisamchk': myisamchk. crashes, go to Stage 3.

*Stage 3: Difficult repair*

You should reach this stage only if the first 16KB block in the index
file is destroyed or contains incorrect information, or if the index
file is missing. In this case, it is necessary to create a new index
file. Do so as follows:

  1. Move the data file to a safe place.

  2. Use the table description file to create new (empty) data and
     index files:

          shell> mysql DB_NAME
          mysql> SET autocommit=1;
          mysql> TRUNCATE TABLE TBL_NAME;
          mysql> quit

  3. Copy the old data file back onto the newly created data file. (Do
     not just move the old file back onto the new file.  You want to
     retain a copy in case something goes wrong.)

*Important*:

If you are using replication, you should stop it prior to performing
the above procedure, since it involves file system operations, and
these are not logged by MySQL.

Go back to Stage 2. *Note `myisamchk -r -q': myisamchk. should work.
(This should not be an endless loop.)

You can also use the `REPAIR TABLE TBL_NAME USE_FRM' SQL statement,
which performs the whole procedure automatically.  There is also no
possibility of unwanted interaction between a utility and the server,
because the server does all the work when you use *Note `REPAIR TABLE':
repair-table. See *Note repair-table::.

*Stage 4: Very difficult repair*

You should reach this stage only if the `.frm' description file has
also crashed.  That should never happen, because the description file
is not changed after the table is created:

  1. Restore the description file from a backup and go back to Stage 3.
     You can also restore the index file and go back to Stage 2. In the
     latter case, you should start with *Note `myisamchk -r': myisamchk.

  2. If you do not have a backup but know exactly how the table was
     created, create a copy of the table in another database.  Remove
     the new data file, and then move the `.frm' description and `.MYI'
     index files from the other database to your crashed database. This
     gives you new description and index files, but leaves the `.MYD'
     data file alone. Go back to Stage 2 and attempt to reconstruct the
     index file.


File: manual.info,  Node: table-optimization,  Next: table-info,  Prev: repair,  Up: table-maintenance

6.5.4 Table Optimization
------------------------

To coalesce fragmented rows and eliminate wasted space that results
from deleting or updating rows, run *Note `myisamchk': myisamchk. in
recovery mode:

     shell> myisamchk -r TBL_NAME

You can optimize a table in the same way by using the *Note `OPTIMIZE
TABLE': optimize-table. SQL statement.  *Note `OPTIMIZE TABLE':
optimize-table. does a table repair and a key analysis, and also sorts
the index tree so that key lookups are faster. There is also no
possibility of unwanted interaction between a utility and the server,
because the server does all the work when you use *Note `OPTIMIZE
TABLE': optimize-table. See *Note optimize-table::.

*Note `myisamchk': myisamchk. has a number of other options that you
can use to improve the performance of a table:

   * `--analyze', `-a'

   * `--sort-index', `-S'

   * `--sort-records=INDEX_NUM', `-R INDEX_NUM'

For a full description of all available options, see *Note myisamchk::.


File: manual.info,  Node: table-info,  Next: maintenance-schedule,  Prev: table-optimization,  Up: table-maintenance

6.5.5 Getting Information About a Table
---------------------------------------

To obtain a description of a table or statistics about it, use the
commands shown here. We explain some of the information in more detail
later.

   * *Note `myisamchk -d TBL_NAME': myisamchk.

     Runs *Note `myisamchk': myisamchk. in `describe mode' to produce a
     description of your table. If you start the MySQL server with
     external locking disabled, *Note `myisamchk': myisamchk. may
     report an error for a table that is updated while it runs.
     However, because *Note `myisamchk': myisamchk. does not change the
     table in describe mode, there is no risk of destroying data.

   * *Note `myisamchk -d -v TBL_NAME': myisamchk.

     Adding `-v' runs *Note `myisamchk': myisamchk.  in verbose mode so
     that it produces more information about what it is doing.

   * *Note `myisamchk -eis TBL_NAME': myisamchk.

     Shows only the most important information from a table. This
     operation is slow because it must read the entire table.

   * *Note `myisamchk -eiv TBL_NAME': myisamchk.

     This is like `-eis', but tells you what is being done.

The TBL_NAME argument can be either the name of a `MyISAM' table or the
name of its index file, as described in *Note myisamchk::.  Multiple
TBL_NAME arguments can be given.

Sample output for some of these commands follows. They are based on a
table with these data and index file sizes:

     -rw-rw-r--   1 monty    tcx     317235748 Jan 12 17:30 company.MYD
     -rw-rw-r--   1 davida   tcx      96482304 Jan 12 18:35 company.MYI

Example of *Note `myisamchk -d': myisamchk. output:

     MyISAM file:     company.MYI
     Record format:   Fixed length
     Data records:    1403698  Deleted blocks:         0
     Recordlength:    226

     table description:
     Key Start Len Index   Type
     1   2     8   unique  double
     2   15    10  multip. text packed stripped
     3   219   8   multip. double
     4   63    10  multip. text packed stripped
     5   167   2   multip. unsigned short
     6   177   4   multip. unsigned long
     7   155   4   multip. text
     8   138   4   multip. unsigned long
     9   177   4   multip. unsigned long
         193   1           text

Example of *Note `myisamchk -d -v': myisamchk. output:

     MyISAM file:         company
     Record format:       Fixed length
     File-version:        1
     Creation time:       1999-10-30 12:12:51
     Recover time:        1999-10-31 19:13:01
     Status:              checked
     Data records:            1403698  Deleted blocks:              0
     Datafile parts:          1403698  Deleted data:                0
     Datafile pointer (bytes):      3  Keyfile pointer (bytes):     3
     Max datafile length:  3791650815  Max keyfile length: 4294967294
     Recordlength:                226

     table description:
     Key Start Len Index   Type                  Rec/key     Root Blocksize
     1   2     8   unique  double                      1 15845376      1024
     2   15    10  multip. text packed stripped        2 25062400      1024
     3   219   8   multip. double                     73 40907776      1024
     4   63    10  multip. text packed stripped        5 48097280      1024
     5   167   2   multip. unsigned short           4840 55200768      1024
     6   177   4   multip. unsigned long            1346 65145856      1024
     7   155   4   multip. text                     4995 75090944      1024
     8   138   4   multip. unsigned long              87 85036032      1024
     9   177   4   multip. unsigned long             178 96481280      1024
         193   1           text

Example of *Note `myisamchk -eis': myisamchk. output:

     Checking MyISAM file: company
     Key:  1:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     Key:  2:  Keyblocks used:  98%  Packed:   50%  Max levels:  4
     Key:  3:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     Key:  4:  Keyblocks used:  99%  Packed:   60%  Max levels:  3
     Key:  5:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  6:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  7:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  8:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  9:  Keyblocks used:  98%  Packed:    0%  Max levels:  4
     Total:    Keyblocks used:  98%  Packed:   17%

     Records:          1403698    M.recordlength:     226
     Packed:             0%
     Recordspace used:     100%   Empty space:          0%
     Blocks/Record:   1.00
     Record blocks:    1403698    Delete blocks:        0
     Recorddata:     317235748    Deleted data:         0
     Lost space:             0    Linkdata:             0

     User time 1626.51, System time 232.36
     Maximum resident set size 0, Integral resident set size 0
     Non physical pagefaults 0, Physical pagefaults 627, Swaps 0
     Blocks in 0 out 0, Messages in 0 out 0, Signals 0
     Voluntary context switches 639, Involuntary context switches 28966

Example of *Note `myisamchk -eiv': myisamchk. output:

     Checking MyISAM file: company
     Data records: 1403698   Deleted blocks:       0
     - check file-size
     - check delete-chain
     block_size 1024:
     index  1:
     index  2:
     index  3:
     index  4:
     index  5:
     index  6:
     index  7:
     index  8:
     index  9:
     No recordlinks
     - check index reference
     - check data record references index: 1
     Key:  1:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     - check data record references index: 2
     Key:  2:  Keyblocks used:  98%  Packed:   50%  Max levels:  4
     - check data record references index: 3
     Key:  3:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     - check data record references index: 4
     Key:  4:  Keyblocks used:  99%  Packed:   60%  Max levels:  3
     - check data record references index: 5
     Key:  5:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 6
     Key:  6:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 7
     Key:  7:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 8
     Key:  8:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 9
     Key:  9:  Keyblocks used:  98%  Packed:    0%  Max levels:  4
     Total:    Keyblocks used:   9%  Packed:   17%

     - check records and index references
     *** LOTS OF ROW NUMBERS DELETED ***

     Records:         1403698   M.recordlength:   226   Packed:           0%
     Recordspace used:    100%  Empty space:        0%  Blocks/Record: 1.00
     Record blocks:   1403698   Delete blocks:      0
     Recorddata:    317235748   Deleted data:       0
     Lost space:            0   Linkdata:           0

     User time 1639.63, System time 251.61
     Maximum resident set size 0, Integral resident set size 0
     Non physical pagefaults 0, Physical pagefaults 10580, Swaps 0
     Blocks in 4 out 0, Messages in 0 out 0, Signals 0
     Voluntary context switches 10604, Involuntary context switches 122798

Explanations for the types of information *Note `myisamchk': myisamchk.
produces are given here.  `Keyfile' refers to the index file.  `Record'
and `row' are synonymous.

   * `MyISAM file'

     Name of the `MyISAM' (index) file.

   * `File-version'

     Version of `MyISAM' format. Currently always 2.

   * `Creation time'

     When the data file was created.

   * `Recover time'

     When the index/data file was last reconstructed.

   * `Data records'

     How many rows are in the table.

   * `Deleted blocks'

     How many deleted blocks still have reserved space. You can
     optimize your table to minimize this space. See *Note
     table-optimization::.

   * `Datafile parts'

     For dynamic-row format, this indicates how many data blocks there
     are. For an optimized table without fragmented rows, this is the
     same as `Data records'.

   * `Deleted data'

     How many bytes of unreclaimed deleted data there are. You can
     optimize your table to minimize this space. See *Note
     table-optimization::.

   * `Datafile pointer'

     The size of the data file pointer, in bytes. It is usually 2, 3,
     4, or 5 bytes. Most tables manage with 2 bytes, but this cannot be
     controlled from MySQL yet. For fixed tables, this is a row
     address. For dynamic tables, this is a byte address.

   * `Keyfile pointer'

     The size of the index file pointer, in bytes. It is usually 1, 2,
     or 3 bytes. Most tables manage with 2 bytes, but this is
     calculated automatically by MySQL. It is always a block address.

   * `Max datafile length'

     How long the table data file can become, in bytes.

   * `Max keyfile length'

     How long the table index file can become, in bytes.

   * `Recordlength'

     How much space each row takes, in bytes.

   * `Record format'

     The format used to store table rows. The preceding examples use
     `Fixed length'. Other possible values are `Compressed' and
     `Packed'.

   * `table description'

     A list of all keys in the table. For each key, *Note `myisamchk':
     myisamchk. displays some low-level information:

        * `Key'

          This key's number.

        * `Start'

          Where in the row this portion of the index starts.

        * `Len'

          How long this portion of the index is. For packed numbers,
          this should always be the full length of the column. For
          strings, it may be shorter than the full length of the
          indexed column, because you can index a prefix of a string
          column.

        * `Index'

          Whether a key value can exist multiple times in the index.
          Possible values are `unique' or `multip.' (multiple).

        * `Type'

          What data type this portion of the index has. This is a
          `MyISAM' data type with the possible values `packed',
          `stripped', or `empty'.

        * `Root'

          Address of the root index block.

        * `Blocksize'

          The size of each index block. By default this is 1024, but
          the value may be changed at compile time when MySQL is built
          from source.

        * `Rec/key'

          This is a statistical value used by the optimizer. It tells
          how many rows there are per value for this index.  A unique
          index always has a value of 1. This may be updated after a
          table is loaded (or greatly changed) with *Note `myisamchk
          -a': myisamchk. If this is not updated at all, a default
          value of 30 is given.

     For the table shown in the examples, there are two `table
     description' lines for the ninth index. This indicates that it is
     a multiple-part index with two parts.

   * `Keyblocks used'

     What percentage of the keyblocks are used. When a table has just
     been reorganized with *Note `myisamchk': myisamchk, as for the
     table in the examples, the values are very high (very near
     theoretical maximum).

   * `Packed'

     MySQL tries to pack key values that have a common suffix.  This
     can only be used for indexes on *Note `CHAR': char. and *Note
     `VARCHAR': char. columns. For long indexed strings that have
     similar leftmost parts, this can significantly reduce the space
     used. In the third of the preceding examples, the fourth key is 10
     characters long and a 60% reduction in space is achieved.

   * `Max levels'

     How deep the B-tree for this key is. Large tables with long key
     values get high values.

   * `Records'

     How many rows are in the table.

   * `M.recordlength'

     The average row length. This is the exact row length for tables
     with fixed-length rows, because all rows have the same length.

   * `Packed'

     MySQL strips spaces from the end of strings. The `Packed' value
     indicates the percentage of savings achieved by doing this.

   * `Recordspace used'

     What percentage of the data file is used.

   * `Empty space'

     What percentage of the data file is unused.

   * `Blocks/Record'

     Average number of blocks per row (that is, how many links a
     fragmented row is composed of). This is always 1.0 for
     fixed-format tables. This value should stay as close to 1.0 as
     possible. If it gets too large, you can reorganize the table. See
     *Note table-optimization::.

   * `Recordblocks'

     How many blocks (links) are used. For fixed-format tables, this is
     the same as the number of rows.

   * `Deleteblocks'

     How many blocks (links) are deleted.

   * `Recorddata'

     How many bytes in the data file are used.

   * `Deleted data'

     How many bytes in the data file are deleted (unused).

   * `Lost space'

     If a row is updated to a shorter length, some space is lost.  This
     is the sum of all such losses, in bytes.

   * `Linkdata'

     When the dynamic table format is used, row fragments are linked
     with pointers (4 to 7 bytes each).  `Linkdata' is the sum of the
     amount of storage used by all such pointers.

If a table has been compressed with *Note `myisampack': myisampack,
*Note `myisamchk -d': myisamchk.  prints additional information about
each table column. See *Note myisampack::, for an example of this
information and a description of what it means.


File: manual.info,  Node: maintenance-schedule,  Prev: table-info,  Up: table-maintenance

6.5.6 Setting Up a Table Maintenance Schedule
---------------------------------------------

It is a good idea to perform table checks on a regular basis rather
than waiting for problems to occur. One way to check and repair
`MyISAM' tables is with the *Note `CHECK TABLE': check-table. and *Note
`REPAIR TABLE': repair-table. statements. See *Note check-table::, and
*Note repair-table::.

Another way to check tables is to use *Note `myisamchk': myisamchk. For
maintenance purposes, you can use *Note `myisamchk -s': myisamchk. The
`-s' option (short for `--silent') causes *Note `myisamchk': myisamchk.
to run in silent mode, printing messages only when errors occur.

It is also a good idea to enable automatic `MyISAM' table checking. For
example, whenever the machine has done a restart in the middle of an
update, you usually need to check each table that could have been
affected before it is used further. (These are `expected crashed
tables.') To check `MyISAM' tables automatically, start the server with
the `--myisam-recover' option. See *Note server-options::.

You should also check your tables regularly during normal system
operation. For example, you can run a `cron' job to check important
tables once a week, using a line like this in a `crontab' file:

     35 0 * * 0 /PATH/TO/MYISAMCHK --fast --silent /PATH/TO/DATADIR/*/*.MYI

This prints out information about crashed tables so that you can
examine and repair them as necessary.

We recommend that to start with, you execute *Note `myisamchk -s':
myisamchk. each night on all tables that have been updated during the
last 24 hours. As you see that problems occur infrequently, you can
back off the checking frequency to once a week or so.

Normally, MySQL tables need little maintenance. If you are performing
many updates to `MyISAM' tables with dynamic-sized rows (tables with
*Note `VARCHAR': char, *Note `BLOB': blob, or *Note `TEXT': blob.
columns) or have tables with many deleted rows you may want to
defragment/reclaim space from the tables from time to time. You can do
this by using *Note `OPTIMIZE TABLE': optimize-table. on the tables in
question. Alternatively, if you can stop the *Note `mysqld': mysqld.
server for a while, change location into the data directory and use
this command while the server is stopped:

     shell> myisamchk -r -s --sort-index --sort_buffer_size=16M */*.MYI


File: manual.info,  Node: optimization,  Next: language-structure,  Prev: backup-and-recovery,  Up: Top

7 Optimization
**************

* Menu:

* optimize-overview::            Optimization Overview
* query-speed::                  Optimizing `SELECT' and Other Statements
* locking-issues::               Locking Issues
* optimizing-database-structure::  Optimizing Database Structure
* optimizing-the-server::        Optimizing the MySQL Server
* disk-issues::                  Disk Issues

Optimization is a complex task because ultimately it requires
understanding of the entire system to be optimized. Although it may be
possible to perform some local optimizations with little knowledge of
your system or application, the more optimal you want your system to
become, the more you must know about it.

This chapter tries to explain and give some examples of different ways
to optimize MySQL. Remember, however, that there are always additional
ways to make the system even faster, although they may require
increasing effort to achieve.


File: manual.info,  Node: optimize-overview,  Next: query-speed,  Prev: optimization,  Up: optimization

7.1 Optimization Overview
=========================

* Menu:

* design-limitations::           MySQL Design Limitations and Tradeoffs
* portability::                  Designing Applications for Portability
* internal-use::                 What We Have Used MySQL For
* mysql-benchmarks::             The MySQL Benchmark Suite
* custom-benchmarks::            Using Your Own Benchmarks

The most important factor in making a system fast is its basic design.
You must also know what kinds of processing your system is doing, and
what its bottlenecks are. In most cases, system bottlenecks arise from
these sources:

   * Disk seeks. It takes time for the disk to find a piece of data.
     With modern disks, the mean time for this is usually lower than
     10ms, so we can in theory do about 100 seeks a second. This time
     improves slowly with new disks and is very hard to optimize for a
     single table. The way to optimize seek time is to distribute the
     data onto more than one disk.

   * Disk reading and writing. When the disk is at the correct
     position, we need to read the data. With modern disks, one disk
     delivers at least 10-20MB/s throughput. This is easier to optimize
     than seeks because you can read in parallel from multiple disks.

   * CPU cycles. When we have the data in main memory, we need to
     process it to get our result. Having small tables compared to the
     amount of memory is the most common limiting factor. But with
     small tables, speed is usually not the problem.

   * Memory bandwidth. When the CPU needs more data than can fit in the
     CPU cache, main memory bandwidth becomes a bottleneck.  This is an
     uncommon bottleneck for most systems, but one to be aware of.

MySQL Enterprise

For instant notification of system bottlenecks subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: design-limitations,  Next: portability,  Prev: optimize-overview,  Up: optimize-overview

7.1.1 MySQL Design Limitations and Tradeoffs
--------------------------------------------

When using the `MyISAM' storage engine, MySQL uses extremely fast table
locking that allows multiple readers or a single writer. The biggest
problem with this storage engine occurs when you have a steady stream
of mixed updates and slow selects on a single table. If this is a
problem for certain tables, you can use another storage engine for
them. See *Note storage-engines::.

MySQL can work with both transactional and non-transactional tables. To
make it easier to work smoothly with non-transactional tables (which
cannot roll back if something goes wrong), MySQL has the following
rules. Note that these rules apply _only_ when not running in strict
SQL mode or if you use the `IGNORE' specifier for *Note `INSERT':
insert. or *Note `UPDATE': update.

   * All columns have default values.

   * If you insert an inappropriate or out-of-range value into a
     column, MySQL sets the column to the `best possible value' instead
     of reporting an error. For numerical values, this is 0, the
     smallest possible value or the largest possible value. For
     strings, this is either the empty string or as much of the string
     as can be stored in the column.

   * All calculated expressions return a value that can be used instead
     of signaling an error condition. For example, 1/0 returns `NULL'.

To change the preceding behaviors, you can enable stricter data
handling by setting the server SQL mode appropriately. For more
information about data handling, see *Note constraints::, *Note
server-sql-mode::, and *Note insert::.


File: manual.info,  Node: portability,  Next: internal-use,  Prev: design-limitations,  Up: optimize-overview

7.1.2 Designing Applications for Portability
--------------------------------------------

Because all SQL servers implement different parts of standard SQL, it
takes work to write portable database applications. It is very easy to
achieve portability for very simple selects and inserts, but becomes
more difficult the more capabilities you require. If you want an
application that is fast with many database systems, it becomes even
more difficult.

All database systems have some weak points. That is, they have
different design compromises that lead to different behavior.

To make a complex application portable, you need to determine which SQL
servers it must work with, and then determine what features those
servers support. You can use the MySQL `crash-me' program to find
functions, types, and limits that you can use with a selection of
database servers. `crash-me' does not check for every possible feature,
but it is still reasonably comprehensive, performing about 450 tests.
An example of the type of information `crash-me' can provide is that you
should not use column names that are longer than 18 characters if you
want to be able to use Informix or DB2.

The `crash-me' program and the MySQL benchmarks are all very database
independent. By taking a look at how they are written, you can get a
feeling for what you must do to make your own applications database
independent. The programs can be found in the `sql-bench' directory of
MySQL source distributions. They are written in Perl and use the DBI
database interface. Use of DBI in itself solves part of the portability
problem because it provides database-independent access methods. See
*Note mysql-benchmarks::.

If you strive for database independence, you need to get a good feeling
for each SQL server's bottlenecks. For example, MySQL is very fast in
retrieving and updating rows for `MyISAM' tables, but has a problem in
mixing slow readers and writers on the same table. Transactional
database systems in general are not very good at generating summary
tables from log tables, because in this case row locking is almost
useless.

MySQL Enterprise

For expert advice on choosing the database engine suitable to your
circumstances subscribe to the MySQL Enterprise Monitor.  For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

To make your application _really_ database independent, you should
define an easily extendable interface through which you manipulate your
data. For example, C++ is available on most systems, so it makes sense
to use a C++ class-based interface to the databases.

If you use some feature that is specific to a given database system
(such as the *Note `REPLACE': replace.  statement, which is specific to
MySQL), you should implement the same feature for other SQL servers by
coding an alternative method. Although the alternative might be slower,
it enables the other servers to perform the same tasks.

With MySQL, you can use the `/*! */' syntax to add MySQL-specific
keywords to a statement. The code inside `/* */' is treated as a
comment (and ignored) by most other SQL servers. For information about
writing comments, see *Note comments::.

If high performance is more important than exactness, as for some Web
applications, it is possible to create an application layer that caches
all results to give you even higher performance. By letting old results
expire after a while, you can keep the cache reasonably fresh. This
provides a method to handle high load spikes, in which case you can
dynamically increase the cache size and set the expiration timeout
higher until things get back to normal.

In this case, the table creation information should contain information
about the initial cache size and how often the table should normally be
refreshed.

An attractive alternative to implementing an application cache is to
use the MySQL query cache. By enabling the query cache, the server
handles the details of determining whether a query result can be
reused. This simplifies your application. See *Note query-cache::.


File: manual.info,  Node: internal-use,  Next: mysql-benchmarks,  Prev: portability,  Up: optimize-overview

7.1.3 What We Have Used MySQL For
---------------------------------

This section describes an early application for MySQL.

During MySQL initial development, the features of MySQL were made to
fit our largest customer, which handled data warehousing for a couple
of the largest retailers in Sweden.

From all stores, we got weekly summaries of all bonus card
transactions, and were expected to provide useful information for the
store owners to help them find how their advertising campaigns were
affecting their own customers.

The volume of data was quite huge (about seven million summary
transactions per month), and we had data for 4-10 years that we needed
to present to the users. We got weekly requests from our customers, who
wanted instant access to new reports from this data.

We solved this problem by storing all information per month in
compressed `transaction tables.' We had a set of simple macros that
generated summary tables grouped by different criteria (product group,
customer id, store, and so on) from the tables in which the
transactions were stored. The reports were Web pages that were
dynamically generated by a small Perl script. This script parsed a Web
page, executed the SQL statements in it, and inserted the results. We
would have used PHP or `mod_perl' instead, but they were not available
at the time.

For graphical data, we wrote a simple tool in C that could process SQL
query results and produce GIF images based on those results. This tool
also was dynamically executed from the Perl script that parses the Web
pages.

In most cases, a new report could be created simply by copying an
existing script and modifying the SQL query that it used. In some
cases, we needed to add more columns to an existing summary table or
generate a new one. This also was quite simple because we kept all
transaction-storage tables on disk. (This amounted to about 50GB of
transaction tables and 200GB of other customer data.)

We also let our customers access the summary tables directly with ODBC
so that the advanced users could experiment with the data themselves.

This system worked well and we had no problems handling the data with
quite modest Sun Ultra SPARCstation hardware (2x200MHz). Eventually the
system was migrated to Linux.


File: manual.info,  Node: mysql-benchmarks,  Next: custom-benchmarks,  Prev: internal-use,  Up: optimize-overview

7.1.4 The MySQL Benchmark Suite
-------------------------------

This benchmark suite is meant to tell any user what operations a given
SQL implementation performs well or poorly. You can get a good idea for
how the benchmarks work by looking at the code and results in the
`sql-bench' directory in any MySQL source distribution.

Note that this benchmark is single-threaded, so it measures the minimum
time for the operations performed. We plan to add multi-threaded tests
to the benchmark suite in the future.

To use the benchmark suite, the following requirements must be
satisfied:

   * The benchmark suite is provided with MySQL source distributions.
     You can either download a released distribution from
     `http://dev.mysql.com/downloads/', or use the current development
     source tree. (See *Note installing-source-tree::.)

   * The benchmark scripts are written in Perl and use the Perl DBI
     module to access database servers, so DBI must be installed. You
     also need the server-specific DBD drivers for each of the servers
     you want to test. For example, to test MySQL, PostgreSQL, and DB2,
     you must have the `DBD::mysql', `DBD::Pg', and `DBD::DB2' modules
     installed. See *Note perl-support::.

After you obtain a MySQL source distribution, you can find the
benchmark suite located in its `sql-bench' directory. To run the
benchmark tests, build MySQL, and then change location into the
`sql-bench' directory and execute the `run-all-tests' script:

     shell> cd sql-bench
     shell> perl run-all-tests --server=SERVER_NAME

SERVER_NAME should be the name of one of the supported servers. To get
a list of all options and supported servers, invoke this command:

     shell> perl run-all-tests --help

The `crash-me' script also is located in the `sql-bench' directory.
`crash-me' tries to determine what features a database system supports
and what its capabilities and limitations are by actually running
queries. For example, it determines:

   * What data types are supported

   * How many indexes are supported

   * What functions are supported

   * How big a query can be

   * How big a *Note `VARCHAR': char. column can be

For more information about benchmark results, visit
`http://www.mysql.com/why-mysql/benchmarks/'.


File: manual.info,  Node: custom-benchmarks,  Prev: mysql-benchmarks,  Up: optimize-overview

7.1.5 Using Your Own Benchmarks
-------------------------------

You should definitely benchmark your application and database to find
out where the bottlenecks are. After fixing one bottleneck (or by
replacing it with a `dummy' module), you can proceed to identify the
next bottleneck. Even if the overall performance for your application
currently is acceptable, you should at least make a plan for each
bottleneck and decide how to solve it if someday you really need the
extra performance.

For examples of portable benchmark programs, look at those in the MySQL
benchmark suite. See *Note mysql-benchmarks::. You can take any program
from this suite and modify it for your own needs. By doing this, you
can try different solutions to your problem and test which really is
fastest for you.

Another free benchmark suite is the Open Source Database Benchmark,
available at `http://osdb.sourceforge.net/'.

It is very common for a problem to occur only when the system is very
heavily loaded. We have had many customers who contact us when they
have a (tested) system in production and have encountered load
problems. In most cases, performance problems turn out to be due to
issues of basic database design (for example, table scans are not good
under high load) or problems with the operating system or libraries.
Most of the time, these problems would be much easier to fix if the
systems were not already in production.

To avoid problems like this, you should put some effort into
benchmarking your whole application under the worst possible load:

   * The *Note `mysqlslap': mysqlslap. program can be helpful for
     simulating a high load produced by multiple clients issuing
     queries simultaneously. See *Note mysqlslap::.

   * You can also try Super Smack, available at
     `http://jeremy.zawodny.com/mysql/super-smack/'.

As suggested by the names of these programs, they can bring a system to
its knees, so make sure to use them only on your development systems.


File: manual.info,  Node: query-speed,  Next: locking-issues,  Prev: optimize-overview,  Up: optimization

7.2 Optimizing `SELECT' and Other Statements
============================================

* Menu:

* using-explain::                Optimizing Queries with `EXPLAIN'
* estimating-performance::       Estimating Query Performance
* select-speed::                 Speed of `SELECT' Queries
* where-optimizations::          `WHERE' Clause Optimization
* range-optimization::           Range Optimization
* index-merge-optimization::     Index Merge Optimization
* condition-pushdown-optimization::  Condition Pushdown Optimization
* index-condition-pushdown-optimization::  Index Condition Pushdown Optimization
* is-null-optimization::         `IS NULL' Optimization
* left-join-optimization::       `LEFT JOIN' and `RIGHT JOIN' Optimization
* nested-loop-joins::            Nested-Loop Join Algorithms
* nested-join-optimization::     Nested Join Optimization
* outer-join-simplification::    Outer Join Simplification
* mrr-optimization::             Multi-Range Read Optimization
* bnl-bka-optimization::         Block Nested-Loop and Batched Key Access Joins
* order-by-optimization::        `ORDER BY' Optimization
* group-by-optimization::        `GROUP BY' Optimization
* distinct-optimization::        `DISTINCT' Optimization
* in-subquery-optimization::     Optimizing `IN'/`=ANY' Subqueries
* limit-optimization::           `LIMIT' Optimization
* switchable-optimizations::     Using `optimizer_switch' to Control Optimizations
* how-to-avoid-table-scan::      How to Avoid Table Scans
* information-schema-optimization::  `INFORMATION_SCHEMA' Optimization
* insert-speed::                 Speed of `INSERT' Statements
* update-speed::                 Speed of `UPDATE' Statements
* delete-speed::                 Speed of `DELETE' Statements
* miscellaneous-optimization-tips::  Other Optimization Tips

First, one factor affects all statements: The more complex your
permissions setup, the more overhead you have. Using simpler
permissions when you issue *Note `GRANT': grant.  statements enables
MySQL to reduce permission-checking overhead when clients execute
statements. For example, if you do not grant any table-level or
column-level privileges, the server need not ever check the contents of
the `tables_priv' and `columns_priv' tables. Similarly, if you place no
resource limits on any accounts, the server does not have to perform
resource counting. If you have a very high statement-processing load,
it may be worth the time to use a simplified grant structure to reduce
permission-checking overhead.

If your problem is with a specific MySQL expression or function, you
can perform a timing test by invoking the `BENCHMARK()' function using
the *Note `mysql': mysql. client program. Its syntax is
`BENCHMARK(LOOP_COUNT,EXPRESSION)'.  The return value is always zero,
but *Note `mysql': mysql.  prints a line displaying approximately how
long the statement took to execute. For example:

     mysql> SELECT BENCHMARK(1000000,1+1);
     +------------------------+
     | BENCHMARK(1000000,1+1) |
     +------------------------+
     |                      0 |
     +------------------------+
     1 row in set (0.32 sec)

This result was obtained on a Pentium II 400MHz system. It shows that
MySQL can execute 1,000,000 simple addition expressions in 0.32 seconds
on that system.

All MySQL functions should be highly optimized, but there may be some
exceptions. `BENCHMARK()' is an excellent tool for finding out if some
function is a problem for your queries.


File: manual.info,  Node: using-explain,  Next: estimating-performance,  Prev: query-speed,  Up: query-speed

7.2.1 Optimizing Queries with `EXPLAIN'
---------------------------------------

The *Note `EXPLAIN': explain. statement can be used either as a synonym
for *Note `DESCRIBE': describe.  or as a way to obtain information
about how MySQL executes a *Note `SELECT': select. statement:

   * `EXPLAIN TBL_NAME' is synonymous with `DESCRIBE TBL_NAME' or `SHOW
     COLUMNS FROM TBL_NAME':

          EXPLAIN TBL_NAME

   * When you precede a *Note `SELECT': select.  statement with the
     keyword *Note `EXPLAIN': explain, MySQL displays information from
     the optimizer about the query execution plan. That is, MySQL
     explains how it would process the *Note `SELECT': select,
     including information about how tables are joined and in which
     order:

          EXPLAIN [EXTENDED | PARTITIONS] SELECT SELECT_OPTIONS

   * `EXPLAIN PARTITIONS' is useful only when examining queries
     involving partitioned tables. For details, see *Note
     partitioning-info::.

This section describes the second use of *Note `EXPLAIN': explain. for
obtaining query execution plan information. See also *Note explain::.
For a description of the *Note `DESCRIBE': describe.  and *Note `SHOW
COLUMNS': show-columns. statements, see *Note describe::, and *Note
show-columns::.

With the help of *Note `EXPLAIN': explain, you can see where you should
add indexes to tables to get a faster *Note `SELECT': select. that uses
indexes to find rows. You can also use *Note `EXPLAIN': explain. to
check whether the optimizer joins the tables in an optimal order. To
give a hint to the optimizer to use a join order corresponding to the
order in which the tables are named in the *Note `SELECT': select.
statement, begin the statement with `SELECT STRAIGHT_JOIN' rather than
just *Note `SELECT': select. (See *Note select::.)

If you have a problem with indexes not being used when you believe that
they should be, you should run *Note `ANALYZE TABLE': analyze-table. to
update table statistics such as cardinality of keys, that can affect the
choices the optimizer makes. See *Note analyze-table::.

*Note `EXPLAIN': explain. returns a row of information for each table
used in the *Note `SELECT': select. statement. The tables are listed in
the output in the order that MySQL would read them while processing the
query. MySQL resolves all joins using a _single-sweep multi-join_
method. This means that MySQL reads a row from the first table, and then
finds a matching row in the second table, the third table, and so on.
When all tables are processed, MySQL outputs the selected columns and
backtracks through the table list until a table is found for which
there are more matching rows. The next row is read from this table and
the process continues with the next table.

When the `EXTENDED' keyword is used, *Note `EXPLAIN': explain. produces
extra information that can be viewed by issuing a *Note `SHOW
WARNINGS': show-warnings. statement following the *Note `EXPLAIN':
explain. statement. This information displays how the optimizer
qualifies table and column names in the *Note `SELECT': select.
statement, what the *Note `SELECT': select. looks like after the
application of rewriting and optimization rules, and possibly other
notes about the optimization process.  `EXPLAIN EXTENDED' also displays
the `filtered' column.

*Note*:

You cannot use the `EXTENDED' and `PARTITIONS' keywords together in the
same *Note `EXPLAIN': explain. statement.

Each output row from *Note `EXPLAIN': explain.  provides information
about one table, and each row contains the following columns:

   * `id'

     The *Note `SELECT': select. identifier. This is the sequential
     number of the *Note `SELECT': select. within the query.

   * `select_type'

     The type of *Note `SELECT': select, which can be any of those
     shown in the following table.

     `SIMPLE'          Simple *Note `SELECT': select. (not using *Note
                       `UNION': union. or subqueries)
     `PRIMARY'         Outermost *Note `SELECT': select.
     *Note `UNION':    Second or later *Note `SELECT': select. statement
     union.            in a *Note `UNION': union.
     `DEPENDENT UNION' Second or later *Note `SELECT': select. statement
                       in a *Note `UNION': union, dependent on outer
                       query
     `UNION RESULT'    Result of a *Note `UNION': union.
     `SUBQUERY'        First *Note `SELECT': select. in subquery
     `DEPENDENT        First *Note `SELECT': select. in subquery,
     SUBQUERY'         dependent on outer query
     `DERIVED'         Derived table *Note `SELECT': select. (subquery in
                       `FROM' clause)
     `UNCACHEABLE      A subquery for which the result cannot be cached
     SUBQUERY'         and must be re-evaluated for each row of the
                       outer query
     `UNCACHEABLE      The second or later select in a *Note `UNION':
     UNION'            union.  that belongs to an uncacheable subquery
                       (see `UNCACHEABLE SUBQUERY')

     `DEPENDENT' typically signifies the use of a correlated subquery.
     See *Note correlated-subqueries::.

     `DEPENDENT SUBQUERY' evaluation differs from `UNCACHEABLE
     SUBQUERY' evaluation. For `DEPENDENT SUBQUERY', the subquery is
     re-evaluated only once for each set of different values of the
     variables from its outer context. For `UNCACHEABLE SUBQUERY', the
     subquery is re-evaluated for each row of the outer context.
     Cacheability of subqueries is subject to the restrictions detailed
     in *Note query-cache-operation::. For example, referring to user
     variables makes a subquery uncacheable.

   * `table'

     The table to which the row of output refers.

   * `type'

     The join type. The different join types are listed here, ordered
     from the best type to the worst:

        *  `system'

          The table has only one row (= system table). This is a
          special case of the `const' join type.

        *  `const'

          The table has at most one matching row, which is read at the
          start of the query. Because there is only one row, values
          from the column in this row can be regarded as constants by
          the rest of the optimizer.  `const' tables are very fast
          because they are read only once.

          `const' is used when you compare all parts of a `PRIMARY KEY'
          or `UNIQUE' index to constant values. In the following
          queries, TBL_NAME can be used as a `const' table:

               SELECT * FROM TBL_NAME WHERE PRIMARY_KEY=1;

               SELECT * FROM TBL_NAME
                 WHERE PRIMARY_KEY_PART1=1 AND PRIMARY_KEY_PART2=2;

        *  `eq_ref'

          One row is read from this table for each combination of rows
          from the previous tables. Other than the `system' and `const'
          types, this is the best possible join type. It is used when
          all parts of an index are used by the join and the index is a
          `PRIMARY KEY' or `UNIQUE' index.

          `eq_ref' can be used for indexed columns that are compared
          using the `=' operator. The comparison value can be a
          constant or an expression that uses columns from tables that
          are read before this table. In the following examples, MySQL
          can use an `eq_ref' join to process REF_TABLE:

               SELECT * FROM REF_TABLE,OTHER_TABLE
                 WHERE REF_TABLE.KEY_COLUMN=OTHER_TABLE.COLUMN;

               SELECT * FROM REF_TABLE,OTHER_TABLE
                 WHERE REF_TABLE.KEY_COLUMN_PART1=OTHER_TABLE.COLUMN
                 AND REF_TABLE.KEY_COLUMN_PART2=1;

        *  `ref'

          All rows with matching index values are read from this table
          for each combination of rows from the previous tables. `ref'
          is used if the join uses only a leftmost prefix of the key or
          if the key is not a `PRIMARY KEY' or `UNIQUE' index (in other
          words, if the join cannot select a single row based on the
          key value).  If the key that is used matches only a few rows,
          this is a good join type.

          `ref' can be used for indexed columns that are compared using
          the `=' or `<=>' operator. In the following examples, MySQL
          can use a `ref' join to process REF_TABLE:

               SELECT * FROM REF_TABLE WHERE KEY_COLUMN=EXPR;

               SELECT * FROM REF_TABLE,OTHER_TABLE
                 WHERE REF_TABLE.KEY_COLUMN=OTHER_TABLE.COLUMN;

               SELECT * FROM REF_TABLE,OTHER_TABLE
                 WHERE REF_TABLE.KEY_COLUMN_PART1=OTHER_TABLE.COLUMN
                 AND REF_TABLE.KEY_COLUMN_PART2=1;

        *  `fulltext'

          The join is performed using a `FULLTEXT' index.

        *  `ref_or_null'

          This join type is like `ref', but with the addition that
          MySQL does an extra search for rows that contain `NULL'
          values. This join type optimization is used most often in
          resolving subqueries.  In the following examples, MySQL can
          use a `ref_or_null' join to process REF_TABLE:

               SELECT * FROM REF_TABLE
                 WHERE KEY_COLUMN=EXPR OR KEY_COLUMN IS NULL;

          See *Note is-null-optimization::.

        *  `index_merge'

          This join type indicates that the Index Merge optimization is
          used. In this case, the `key' column in the output row
          contains a list of indexes used, and `key_len' contains a
          list of the longest key parts for the indexes used. For more
          information, see *Note index-merge-optimization::.

        *  `unique_subquery'

          This type replaces `ref' for some `IN' subqueries of the
          following form:

               VALUE IN (SELECT PRIMARY_KEY FROM SINGLE_TABLE WHERE SOME_EXPR)

          `unique_subquery' is just an index lookup function that
          replaces the subquery completely for better efficiency.

        *  `index_subquery'

          This join type is similar to `unique_subquery'. It replaces
          `IN' subqueries, but it works for non-unique indexes in
          subqueries of the following form:

               VALUE IN (SELECT KEY_COLUMN FROM SINGLE_TABLE WHERE SOME_EXPR)

        *  `range'

          Only rows that are in a given range are retrieved, using an
          index to select the rows. The `key' column in the output row
          indicates which index is used.  The `key_len' contains the
          longest key part that was used. The `ref' column is `NULL'
          for this type.

          `range' can be used when a key column is compared to a
          constant using any of the `=', `<>', `>', `>=', `<', `<=',
          `IS NULL', `<=>', `BETWEEN', or `IN()' operators:

               SELECT * FROM TBL_NAME
                 WHERE KEY_COLUMN = 10;

               SELECT * FROM TBL_NAME
                 WHERE KEY_COLUMN BETWEEN 10 and 20;

               SELECT * FROM TBL_NAME
                 WHERE KEY_COLUMN IN (10,20,30);

               SELECT * FROM TBL_NAME
                 WHERE KEY_PART1= 10 AND KEY_PART2 IN (10,20,30);

        *  `index'

          This join type is the same as `ALL', except that only the
          index tree is scanned. This usually is faster than `ALL'
          because the index file usually is smaller than the data file.

          MySQL can use this join type when the query uses only columns
          that are part of a single index.

        *  `ALL'

          A full table scan is done for each combination of rows from
          the previous tables. This is normally not good if the table
          is the first table not marked `const', and usually _very_ bad
          in all other cases.  Normally, you can avoid `ALL' by adding
          indexes that allow row retrieval from the table based on
          constant values or column values from earlier tables.

   * `possible_keys'

     The `possible_keys' column indicates which indexes MySQL can
     choose from use to find the rows in this table. Note that this
     column is totally independent of the order of the tables as
     displayed in the output from *Note `EXPLAIN': explain. That means
     that some of the keys in `possible_keys' might not be usable in
     practice with the generated table order.

     If this column is `NULL', there are no relevant indexes. In this
     case, you may be able to improve the performance of your query by
     examining the `WHERE' clause to check whether it refers to some
     column or columns that would be suitable for indexing. If so,
     create an appropriate index and check the query with *Note
     `EXPLAIN': explain. again. See *Note alter-table::.

     To see what indexes a table has, use `SHOW INDEX FROM TBL_NAME'.

   * `key'

     The `key' column indicates the key (index) that MySQL actually
     decided to use. If MySQL decides to use one of the `possible_keys'
     indexes to look up rows, that index is listed as the key value.

     It is possible that `key' will name an index that is not present
     in the `possible_keys' value. This can happen if none of the
     `possible_keys' indexes are suitable for looking up rows, but all
     the columns selected by the query are columns of some other index.
     That is, the named index covers the selected columns, so although
     it is not used to determine which rows to retrieve, an index scan
     is more efficient than a data row scan.

     For `InnoDB', a secondary index might cover the selected columns
     even if the query also selects the primary key because `InnoDB'
     stores the primary key value with each secondary index. If `key'
     is `NULL', MySQL found no index to use for executing the query more
     efficiently.

     To force MySQL to use or ignore an index listed in the
     `possible_keys' column, use `FORCE INDEX', `USE INDEX', or `IGNORE
     INDEX' in your query. See *Note index-hints::.

     For `MyISAM' tables, running *Note `ANALYZE TABLE': analyze-table.
     helps the optimizer choose better indexes. For `MyISAM' tables,
     *Note `myisamchk --analyze': myisamchk. does the same. See *Note
     analyze-table::, and *Note table-maintenance::.

   * `key_len'

     The `key_len' column indicates the length of the key that MySQL
     decided to use. The length is `NULL' if the `key' column says
     `NULL'. Note that the value of `key_len' enables you to determine
     how many parts of a multiple-part key MySQL actually uses.

   * `ref'

     The `ref' column shows which columns or constants are compared to
     the index named in the `key' column to select rows from the table.

   * `rows'

     The `rows' column indicates the number of rows MySQL believes it
     must examine to execute the query.

   * `filtered'

     The `filtered' column indicates an estimated percentage of table
     rows that will be filtered by the table condition. That is, `rows'
     shows the estimated number of rows examined and `rows' x `filtered'
     / `100' shows the number of rows that will be joined with previous
     tables. This column is displayed if you use `EXPLAIN EXTENDED'.

   * `Extra'

     This column contains additional information about how MySQL
     resolves the query. The following list explains the values that
     can appear in this column. If you want to make your queries as
     fast as possible, you should look out for `Extra' values of `Using
     filesort' and `Using temporary'.

        * `Distinct'

          MySQL is looking for distinct values, so it stops searching
          for more rows for the current row combination after it has
          found the first matching row.

        * `Full scan on NULL key'

          This occurs for subquery optimization as a fallback strategy
          when the optimizer cannot use an index-lookup access method.

        * `Impossible WHERE noticed after reading const tables'

          MySQL has read all `const' (and `system') tables and notice
          that the `WHERE' clause is always false.

        * `No tables'

          The query has no `FROM' clause, or has a `FROM DUAL' clause.

        * `Not exists'

          MySQL was able to do a `LEFT JOIN' optimization on the query
          and does not examine more rows in this table for the previous
          row combination after it finds one row that matches the `LEFT
          JOIN' criteria. Here is an example of the type of query that
          can be optimized this way:

               SELECT * FROM t1 LEFT JOIN t2 ON t1.id=t2.id
                 WHERE t2.id IS NULL;

          Assume that `t2.id' is defined as `NOT NULL'. In this case,
          MySQL scans `t1' and looks up the rows in `t2' using the
          values of `t1.id'. If MySQL finds a matching row in `t2', it
          knows that `t2.id' can never be `NULL', and does not scan
          through the rest of the rows in `t2' that have the same `id'
          value. In other words, for each row in `t1', MySQL needs to do
          only a single lookup in `t2', regardless of how many rows
          actually match in `t2'.

        * `Range checked for each record (index map: N)'

          MySQL found no good index to use, but found that some of
          indexes might be used after column values from preceding
          tables are known. For each row combination in the preceding
          tables, MySQL checks whether it is possible to use a `range'
          or `index_merge' access method to retrieve rows. This is not
          very fast, but is faster than performing a join with no index
          at all. The applicability criteria are as described in *Note
          range-optimization::, and *Note index-merge-optimization::,
          with the exception that all column values for the preceding
          table are known and considered to be constants.

          Indexes are numbered beginning with 1, in the same order as
          shown by *Note `SHOW INDEX': show-index.  for the table. The
          index map value N is a bitmask value that indicates which
          indexes are candidates. For example, a value of `0x19'
          (binary 11001) means that indexes 1, 4, and 5 will be
          considered.

        * `Scanned N databases'

          This indicates how many directory scans the server performs
          when processing a query for `INFORMATION_SCHEMA' tables, as
          described in *Note information-schema-optimization::. The
          value of N can be 0, 1, or `all'.

        * `Select tables optimized away'

          The query contained only aggregate functions (`MIN()',
          `MAX()') that were all resolved using an index, or `COUNT(*)'
          for `MyISAM', and no `GROUP BY' clause. The optimizer
          determined that only one row should be returned.

        * `Skip_open_table', `Open_frm_only', `Open_trigger_only',
          `Open_full_table'

          These values indicate file-opening optimizations that apply
          to queries for `INFORMATION_SCHEMA' tables, as described in
          *Note information-schema-optimization::.

             * `Skip_open_table': Table files do not need to be opened.
               The information has already become available within the
               query by scanning the database directory.

             * `Open_frm_only': Only the table's `.frm' file need be
               opened.

             * `Open_trigger_only': Only the table's `.TRG' file need be
               opened.

             * `Open_full_table': The unoptimized information lookup.
               The `.frm', `.MYD', and `.MYI' files must be opened.

        * `Using filesort'

          MySQL must do an extra pass to find out how to retrieve the
          rows in sorted order. The sort is done by going through all
          rows according to the join type and storing the sort key and
          pointer to the row for all rows that match the `WHERE'
          clause. The keys then are sorted and the rows are retrieved
          in sorted order.  See *Note order-by-optimization::.

        * `Using index'

          The column information is retrieved from the table using only
          information in the index tree without having to do an
          additional seek to read the actual row. This strategy can be
          used when the query uses only columns that are part of a
          single index.

          For `InnoDB' tables that have a user-defined clustered index,
          that index can be used even when `Using index' is absent from
          the `Extra' column. This is the case if `type' is `index' and
          `key' is `PRIMARY'.

        * `Using index condition'

          Tables are read by accessing index tuples and testing them
          first to determine whether to read full table rows.  In this
          way, index information is used to defer (`push down') reading
          full table rows unless it is necessary. See *Note
          index-condition-pushdown-optimization::.

        * `Using index for group-by'

          Similar to the `Using index' table access method, `Using
          index for group-by' indicates that MySQL found an index that
          can be used to retrieve all columns of a `GROUP BY' or
          `DISTINCT' query without any extra disk access to the actual
          table. Additionally, the index is used in the most efficient
          way so that for each group, only a few index entries are
          read. For details, see *Note group-by-optimization::.

        * `Using join buffer'

          Tables from earlier joins are read in portions into the join
          buffer, and then their rows are used from the buffer to
          perform the join with the current table.

        * `Using MRR'

          Tables are read using the Multi-Range Read optimization
          strategy. See *Note mrr-optimization::.

        * `Using sort_union(...)', `Using union(...)', `Using
          intersect(...)'

          These indicate how index scans are merged for the
          `index_merge' join type. See *Note index-merge-optimization::.

        * `Using temporary'

          To resolve the query, MySQL needs to create a temporary table
          to hold the result. This typically happens if the query
          contains `GROUP BY' and `ORDER BY' clauses that list columns
          differently.

        * `Using where'

          A `WHERE' clause is used to restrict which rows to match
          against the next table or send to the client. Unless you
          specifically intend to fetch or examine all rows from the
          table, you may have something wrong in your query if the
          `Extra' value is not `Using where' and the table join type is
          `ALL' or `index'.

You can get a good indication of how good a join is by taking the
product of the values in the `rows' column of the *Note `EXPLAIN':
explain. output. This should tell you roughly how many rows MySQL must
examine to execute the query. If you restrict queries with the
`max_join_size' system variable, this row product also is used to
determine which multiple-table *Note `SELECT': select. statements to
execute and which to abort. See *Note server-parameters::.

The following example shows how a multiple-table join can be optimized
progressively based on the information provided by *Note `EXPLAIN':
explain.

Suppose that you have the *Note `SELECT': select.  statement shown here
and that you plan to examine it using *Note `EXPLAIN': explain.:

     EXPLAIN SELECT tt.TicketNumber, tt.TimeIn,
                    tt.ProjectReference, tt.EstimatedShipDate,
                    tt.ActualShipDate, tt.ClientID,
                    tt.ServiceCodes, tt.RepetitiveID,
                    tt.CurrentProcess, tt.CurrentDPPerson,
                    tt.RecordVolume, tt.DPPrinted, et.COUNTRY,
                    et_1.COUNTRY, do.CUSTNAME
             FROM tt, et, et AS et_1, do
             WHERE tt.SubmitTime IS NULL
               AND tt.ActualPC = et.EMPLOYID
               AND tt.AssignedPC = et_1.EMPLOYID
               AND tt.ClientID = do.CUSTNMBR;

For this example, make the following assumptions:

   * The columns being compared have been declared as follows.

     *Table* *Column*          *Data Type*
     `tt'    `ActualPC'        `CHAR(10)'
     `tt'    `AssignedPC'      `CHAR(10)'
     `tt'    `ClientID'        `CHAR(10)'
     `et'    `EMPLOYID'        `CHAR(15)'
     `do'    `CUSTNMBR'        `CHAR(15)'

   * The tables have the following indexes.

     *Table* *Index*
     `tt'    `ActualPC'
     `tt'    `AssignedPC'
     `tt'    `ClientID'
     `et'    `EMPLOYID' (primary key)
     `do'    `CUSTNMBR' (primary key)

   * The `tt.ActualPC' values are not evenly distributed.

Initially, before any optimizations have been performed, the *Note
`EXPLAIN': explain. statement produces the following information:

     table type possible_keys key  key_len ref  rows  Extra
     et    ALL  PRIMARY       NULL NULL    NULL 74
     do    ALL  PRIMARY       NULL NULL    NULL 2135
     et_1  ALL  PRIMARY       NULL NULL    NULL 74
     tt    ALL  AssignedPC,   NULL NULL    NULL 3872
                ClientID,
                ActualPC
           Range checked for each record (index map: 0x23)

Because `type' is `ALL' for each table, this output indicates that
MySQL is generating a Cartesian product of all the tables; that is,
every combination of rows. This takes quite a long time, because the
product of the number of rows in each table must be examined. For the
case at hand, this product is 74 x 2135 x 74 x 3872 = 45,268,558,720
rows. If the tables were bigger, you can only imagine how long it would
take.

One problem here is that MySQL can use indexes on columns more
efficiently if they are declared as the same type and size. In this
context, *Note `VARCHAR': char. and *Note `CHAR': char. are considered
the same if they are declared as the same size.  `tt.ActualPC' is
declared as `CHAR(10)' and `et.EMPLOYID' is `CHAR(15)', so there is a
length mismatch.

To fix this disparity between column lengths, use *Note `ALTER TABLE':
alter-table. to lengthen `ActualPC' from 10 characters to 15 characters:

     mysql> ALTER TABLE tt MODIFY ActualPC VARCHAR(15);

Now `tt.ActualPC' and `et.EMPLOYID' are both `VARCHAR(15)'. Executing
the *Note `EXPLAIN': explain. statement again produces this result:

     table type   possible_keys key     key_len ref         rows    Extra
     tt    ALL    AssignedPC,   NULL    NULL    NULL        3872    Using
                  ClientID,                                         where
                  ActualPC
     do    ALL    PRIMARY       NULL    NULL    NULL        2135
           Range checked for each record (index map: 0x1)
     et_1  ALL    PRIMARY       NULL    NULL    NULL        74
           Range checked for each record (index map: 0x1)
     et    eq_ref PRIMARY       PRIMARY 15      tt.ActualPC 1

This is not perfect, but is much better: The product of the `rows'
values is less by a factor of 74. This version executes in a couple of
seconds.

A second alteration can be made to eliminate the column length
mismatches for the `tt.AssignedPC = et_1.EMPLOYID' and `tt.ClientID =
do.CUSTNMBR' comparisons:

     mysql> ALTER TABLE tt MODIFY AssignedPC VARCHAR(15),
         ->                MODIFY ClientID   VARCHAR(15);

After that modification, *Note `EXPLAIN': explain.  produces the output
shown here:

     table type   possible_keys key      key_len ref           rows Extra
     et    ALL    PRIMARY       NULL     NULL    NULL          74
     tt    ref    AssignedPC,   ActualPC 15      et.EMPLOYID   52   Using
                  ClientID,                                         where
                  ActualPC
     et_1  eq_ref PRIMARY       PRIMARY  15      tt.AssignedPC 1
     do    eq_ref PRIMARY       PRIMARY  15      tt.ClientID   1

At this point, the query is optimized almost as well as possible. The
remaining problem is that, by default, MySQL assumes that values in the
`tt.ActualPC' column are evenly distributed, and that is not the case
for the `tt' table. Fortunately, it is easy to tell MySQL to analyze
the key distribution:

     mysql> ANALYZE TABLE tt;

With the additional index information, the join is perfect and *Note
`EXPLAIN': explain. produces this result:

     table type   possible_keys key     key_len ref           rows Extra
     tt    ALL    AssignedPC    NULL    NULL    NULL          3872 Using
                  ClientID,                                        where
                  ActualPC
     et    eq_ref PRIMARY       PRIMARY 15      tt.ActualPC   1
     et_1  eq_ref PRIMARY       PRIMARY 15      tt.AssignedPC 1
     do    eq_ref PRIMARY       PRIMARY 15      tt.ClientID   1

Note that the `rows' column in the output from *Note `EXPLAIN':
explain. is an educated guess from the MySQL join optimizer. You should
check whether the numbers are even close to the truth by comparing the
`rows' product with the actual number of rows that the query returns.
If the numbers are quite different, you might get better performance by
using `STRAIGHT_JOIN' in your *Note `SELECT': select. statement and
trying to list the tables in a different order in the `FROM' clause.

It is possible in some cases to execute statements that modify data
when *Note `EXPLAIN SELECT': explain. is used with a subquery; for more
information, see *Note unnamed-views::.

MySQL Enterprise

Subscribers to the MySQL Enterprise Monitor regularly receive expert
advice on optimization. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: estimating-performance,  Next: select-speed,  Prev: using-explain,  Up: query-speed

7.2.2 Estimating Query Performance
----------------------------------

In most cases, you can estimate query performance by counting disk
seeks. For small tables, you can usually find a row in one disk seek
(because the index is probably cached). For bigger tables, you can
estimate that, using B-tree indexes, you need this many seeks to find a
row: `log(ROW_COUNT) / log(INDEX_BLOCK_LENGTH / 3 x 2 / (INDEX_LENGTH +
DATA_POINTER_LENGTH)) + 1'.

In MySQL, an index block is usually 1,024 bytes and the data pointer is
usually four bytes. For a 500,000-row table with an index length of
three bytes (the size of *Note `MEDIUMINT': numeric-types.), the
formula indicates `log(500,000)/log(1024/3x2/(3+4)) + 1' = `4' seeks.

This index would require storage of about 500,000 x 7 x 3/2 = 5.2MB
(assuming a typical index buffer fill ratio of 2/3), so you probably
have much of the index in memory and so need only one or two calls to
read data to find the row.

For writes, however, you need four seek requests to find where to place
a new index value and normally two seeks to update the index and write
the row.

Note that the preceding discussion does not mean that your application
performance slowly degenerates by log N. As long as everything is
cached by the OS or the MySQL server, things become only marginally
slower as the table gets bigger. After the data gets too big to be
cached, things start to go much slower until your applications are
bound only by disk seeks (which increase by log N). To avoid this,
increase the key cache size as the data grows. For `MyISAM' tables, the
key cache size is controlled by the `key_buffer_size' system variable.
See *Note server-parameters::.

MySQL Enterprise

The MySQL Enterprise Monitor provides a number of advisors specifically
designed to improve query performance. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: select-speed,  Next: where-optimizations,  Prev: estimating-performance,  Up: query-speed

7.2.3 Speed of `SELECT' Queries
-------------------------------

In general, when you want to make a slow `SELECT ...  WHERE' query
faster, the first thing to check is whether you can add an index. All
references between different tables should usually be done with
indexes. You can use the *Note `EXPLAIN': explain. statement to
determine which indexes are used for a *Note `SELECT': select. See
*Note using-explain::, and *Note mysql-indexes::.

Some general tips for speeding up queries on `MyISAM' tables:

   * To help MySQL better optimize queries, use *Note `ANALYZE TABLE':
     analyze-table. or run *Note `myisamchk --analyze': myisamchk. on a
     table after it has been loaded with data. This updates a value for
     each index part that indicates the average number of rows that
     have the same value. (For unique indexes, this is always 1.)
     MySQL uses this to decide which index to choose when you join two
     tables based on a non-constant expression. You can check the
     result from the table analysis by using `SHOW INDEX FROM TBL_NAME'
     and examining the `Cardinality' value. *Note `myisamchk
     --description --verbose': myisamchk. shows index distribution
     information.

   * To sort an index and data according to an index, use *Note
     `myisamchk --sort-index --sort-records=1': myisamchk.  (assuming
     that you want to sort on index 1). This is a good way to make
     queries faster if you have a unique index from which you want to
     read all rows in order according to the index. The first time you
     sort a large table this way, it may take a long time.


File: manual.info,  Node: where-optimizations,  Next: range-optimization,  Prev: select-speed,  Up: query-speed

7.2.4 `WHERE' Clause Optimization
---------------------------------

This section discusses optimizations that can be made for processing
`WHERE' clauses. The examples use *Note `SELECT': select. statements,
but the same optimizations apply for `WHERE' clauses in *Note `DELETE':
delete. and *Note `UPDATE': update. statements.

Work on the MySQL optimizer is ongoing, so this section is incomplete.
MySQL performs a great many optimizations, not all of which are
documented here.

Some of the optimizations performed by MySQL follow:

   * Removal of unnecessary parentheses:

             ((a AND b) AND c OR (((a AND b) AND (c AND d))))
          -> (a AND b AND c) OR (a AND b AND c AND d)

   * Constant folding:

             (a<b AND b=c) AND a=5
          -> b>5 AND b=c AND a=5

   * Constant condition removal (needed because of constant folding):

             (B>=5 AND B=5) OR (B=6 AND 5=5) OR (B=7 AND 5=6)
          -> B=5 OR B=6

   * Constant expressions used by indexes are evaluated only once.

   * `COUNT(*)' on a single table without a `WHERE' is retrieved
     directly from the table information for `MyISAM' and `MEMORY'
     tables. This is also done for any `NOT NULL' expression when used
     with only one table.

   * Early detection of invalid constant expressions. MySQL quickly
     detects that some *Note `SELECT': select. statements are
     impossible and returns no rows.

   * `HAVING' is merged with `WHERE' if you do not use `GROUP BY' or
     aggregate functions (`COUNT()', `MIN()', and so on).

   * For each table in a join, a simpler `WHERE' is constructed to get
     a fast `WHERE' evaluation for the table and also to skip rows as
     soon as possible.

   * All constant tables are read first before any other tables in the
     query. A constant table is any of the following:

        * An empty table or a table with one row.

        * A table that is used with a `WHERE' clause on a `PRIMARY KEY'
          or a `UNIQUE' index, where all index parts are compared to
          constant expressions and are defined as `NOT NULL'.

     All of the following tables are used as constant tables:

          SELECT * FROM t WHERE PRIMARY_KEY=1;
          SELECT * FROM t1,t2
            WHERE t1.PRIMARY_KEY=1 AND t2.PRIMARY_KEY=t1.id;

   * The best join combination for joining the tables is found by
     trying all possibilities. If all columns in `ORDER BY' and `GROUP
     BY' clauses come from the same table, that table is preferred
     first when joining.

   * If there is an `ORDER BY' clause and a different `GROUP BY'
     clause, or if the `ORDER BY' or `GROUP BY' contains columns from
     tables other than the first table in the join queue, a temporary
     table is created.

   * If you use the `SQL_SMALL_RESULT' option, MySQL uses an in-memory
     temporary table.

   * Each table index is queried, and the best index is used unless the
     optimizer believes that it is more efficient to use a table scan.
     At one time, a scan was used based on whether the best index
     spanned more than 30% of the table, but a fixed percentage no
     longer determines the choice between using an index or a scan. The
     optimizer now is more complex and bases its estimate on additional
     factors such as table size, number of rows, and I/O block size.

   * In some cases, MySQL can read rows from the index without even
     consulting the data file. If all columns used from the index are
     numeric, only the index tree is used to resolve the query.

   * Before each row is output, those that do not match the `HAVING'
     clause are skipped.

Some examples of queries that are very fast:

     SELECT COUNT(*) FROM TBL_NAME;

     SELECT MIN(KEY_PART1),MAX(KEY_PART1) FROM TBL_NAME;

     SELECT MAX(KEY_PART2) FROM TBL_NAME
       WHERE KEY_PART1=CONSTANT;

     SELECT ... FROM TBL_NAME
       ORDER BY KEY_PART1,KEY_PART2,... LIMIT 10;

     SELECT ... FROM TBL_NAME
       ORDER BY KEY_PART1 DESC, KEY_PART2 DESC, ... LIMIT 10;

MySQL resolves the following queries using only the index tree,
assuming that the indexed columns are numeric:

     SELECT KEY_PART1,KEY_PART2 FROM TBL_NAME WHERE KEY_PART1=VAL;

     SELECT COUNT(*) FROM TBL_NAME
       WHERE KEY_PART1=VAL1 AND KEY_PART2=VAL2;

     SELECT KEY_PART2 FROM TBL_NAME GROUP BY KEY_PART1;

The following queries use indexing to retrieve the rows in sorted order
without a separate sorting pass:

     SELECT ... FROM TBL_NAME
       ORDER BY KEY_PART1,KEY_PART2,... ;

     SELECT ... FROM TBL_NAME
       ORDER BY KEY_PART1 DESC, KEY_PART2 DESC, ... ;


File: manual.info,  Node: range-optimization,  Next: index-merge-optimization,  Prev: where-optimizations,  Up: query-speed

7.2.5 Range Optimization
------------------------

* Menu:

* range-access-single-part::     The Range Access Method for Single-Part Indexes
* range-access-multi-part::      The Range Access Method for Multiple-Part Indexes

The `range' access method uses a single index to retrieve a subset of
table rows that are contained within one or several index value
intervals. It can be used for a single-part or multiple-part index. The
following sections give a detailed description of how intervals are
extracted from the `WHERE' clause.


File: manual.info,  Node: range-access-single-part,  Next: range-access-multi-part,  Prev: range-optimization,  Up: range-optimization

7.2.5.1 The Range Access Method for Single-Part Indexes
.......................................................

For a single-part index, index value intervals can be conveniently
represented by corresponding conditions in the `WHERE' clause, so we
speak of _range conditions_ rather than `intervals.'

The definition of a range condition for a single-part index is as
follows:

   * For both `BTREE' and `HASH' indexes, comparison of a key part with
     a constant value is a range condition when using the `=', `<=>',
     `IN()', `IS NULL', or `IS NOT NULL' operators.

   * For `BTREE' indexes, comparison of a key part with a constant
     value is a range condition when using the `>', `<', `>=', `<=',
     `BETWEEN', `!=', or `<>' operators, or `LIKE' comparisons if the
     argument to `LIKE' is a constant string that does not start with a
     wildcard character.

   * For all types of indexes, multiple range conditions combined with
     `OR' or `AND' form a range condition.

`Constant value' in the preceding descriptions means one of the
following:

   * A constant from the query string

   * A column of a `const' or `system' table from the same join

   * The result of an uncorrelated subquery

   * Any expression composed entirely from subexpressions of the
     preceding types

Here are some examples of queries with range conditions in the `WHERE'
clause:

     SELECT * FROM t1
       WHERE KEY_COL > 1
       AND KEY_COL < 10;

     SELECT * FROM t1
       WHERE KEY_COL = 1
       OR KEY_COL IN (15,18,20);

     SELECT * FROM t1
       WHERE KEY_COL LIKE 'ab%'
       OR KEY_COL BETWEEN 'bar' AND 'foo';

Note that some non-constant values may be converted to constants during
the constant propagation phase.

MySQL tries to extract range conditions from the `WHERE' clause for
each of the possible indexes. During the extraction process, conditions
that cannot be used for constructing the range condition are dropped,
conditions that produce overlapping ranges are combined, and conditions
that produce empty ranges are removed.

Consider the following statement, where `key1' is an indexed column and
`nonkey' is not indexed:

     SELECT * FROM t1 WHERE
       (key1 < 'abc' AND (key1 LIKE 'abcde%' OR key1 LIKE '%b')) OR
       (key1 < 'bar' AND nonkey = 4) OR
       (key1 < 'uux' AND key1 > 'z');

The extraction process for key `key1' is as follows:

  1. Start with original `WHERE' clause:

          (key1 < 'abc' AND (key1 LIKE 'abcde%' OR key1 LIKE '%b')) OR
          (key1 < 'bar' AND nonkey = 4) OR
          (key1 < 'uux' AND key1 > 'z')

  2. Remove `nonkey = 4' and `key1 LIKE '%b'' because they cannot be
     used for a range scan. The correct way to remove them is to replace
     them with `TRUE', so that we do not miss any matching rows when
     doing the range scan. Having replaced them with `TRUE', we get:

          (key1 < 'abc' AND (key1 LIKE 'abcde%' OR TRUE)) OR
          (key1 < 'bar' AND TRUE) OR
          (key1 < 'uux' AND key1 > 'z')

  3. Collapse conditions that are always true or false:

        * `(key1 LIKE 'abcde%' OR TRUE)' is always true

        * `(key1 < 'uux' AND key1 > 'z')' is always false

     Replacing these conditions with constants, we get:

          (key1 < 'abc' AND TRUE) OR (key1 < 'bar' AND TRUE) OR (FALSE)

     Removing unnecessary `TRUE' and `FALSE' constants, we obtain:

          (key1 < 'abc') OR (key1 < 'bar')

  4. Combining overlapping intervals into one yields the final
     condition to be used for the range scan:

          (key1 < 'bar')

In general (and as demonstrated by the preceding example), the
condition used for a range scan is less restrictive than the `WHERE'
clause. MySQL performs an additional check to filter out rows that
satisfy the range condition but not the full `WHERE' clause.

The range condition extraction algorithm can handle nested `AND'/`OR'
constructs of arbitrary depth, and its output does not depend on the
order in which conditions appear in `WHERE' clause.

Currently, MySQL does not support merging multiple ranges for the
`range' access method for spatial indexes. To work around this
limitation, you can use a *Note `UNION': union. with identical *Note
`SELECT': select. statements, except that you put each spatial
predicate in a different *Note `SELECT': select.


File: manual.info,  Node: range-access-multi-part,  Prev: range-access-single-part,  Up: range-optimization

7.2.5.2 The Range Access Method for Multiple-Part Indexes
.........................................................

Range conditions on a multiple-part index are an extension of range
conditions for a single-part index. A range condition on a
multiple-part index restricts index rows to lie within one or several
key tuple intervals. Key tuple intervals are defined over a set of key
tuples, using ordering from the index.

For example, consider a multiple-part index defined as `key1(KEY_PART1,
KEY_PART2, KEY_PART3)', and the following set of key tuples listed in
key order:

     KEY_PART1  KEY_PART2  KEY_PART3
       NULL       1          'abc'
       NULL       1          'xyz'
       NULL       2          'foo'
        1         1          'abc'
        1         1          'xyz'
        1         2          'abc'
        2         1          'aaa'

The condition `KEY_PART1 = 1' defines this interval:

     (1,-inf,-inf) <= (KEY_PART1,KEY_PART2,KEY_PART3) < (1,+inf,+inf)

The interval covers the 4th, 5th, and 6th tuples in the preceding data
set and can be used by the range access method.

By contrast, the condition `KEY_PART3 = 'abc'' does not define a single
interval and cannot be used by the range access method.

The following descriptions indicate how range conditions work for
multiple-part indexes in greater detail.

   * For `HASH' indexes, each interval containing identical values can
     be used. This means that the interval can be produced only for
     conditions in the following form:

              KEY_PART1 CMP CONST1
          AND KEY_PART2 CMP CONST2
          AND ...
          AND KEY_PARTN CMP CONSTN;

     Here, CONST1, CONST2, ... are constants, CMP is one of the `=',
     `<=>', or `IS NULL' comparison operators, and the conditions cover
     all index parts. (That is, there are N conditions, one for each
     part of an N-part index.) For example, the following is a range
     condition for a three-part `HASH' index:

          KEY_PART1 = 1 AND KEY_PART2 IS NULL AND KEY_PART3 = 'foo'

     For the definition of what is considered to be a constant, see
     *Note range-access-single-part::.

   * For a `BTREE' index, an interval might be usable for conditions
     combined with `AND', where each condition compares a key part with
     a constant value using `=', `<=>', `IS NULL', `>', `<', `>=', `<=',
     `!=', `<>', `BETWEEN', or `LIKE 'PATTERN'' (where `'PATTERN'' does
     not start with a wildcard). An interval can be used as long as it
     is possible to determine a single key tuple containing all rows
     that match the condition (or two intervals if `<>' or `!=' is
     used). For example, for this condition:

          KEY_PART1 = 'foo' AND KEY_PART2 >= 10 AND KEY_PART3 > 10

     The single interval is:

          ('foo',10,10) < (KEY_PART1,KEY_PART2,KEY_PART3) < ('foo',+inf,+inf)

     It is possible that the created interval contains more rows than
     the initial condition. For example, the preceding interval
     includes the value `('foo', 11, 0)', which does not satisfy the
     original condition.

   * If conditions that cover sets of rows contained within intervals
     are combined with `OR', they form a condition that covers a set of
     rows contained within the union of their intervals. If the
     conditions are combined with `AND', they form a condition that
     covers a set of rows contained within the intersection of their
     intervals. For example, for this condition on a two-part index:

          (KEY_PART1 = 1 AND KEY_PART2 < 2) OR (KEY_PART1 > 5)

     The intervals are:

          (1,-inf) < (KEY_PART1,KEY_PART2) < (1,2)
          (5,-inf) < (KEY_PART1,KEY_PART2)

     In this example, the interval on the first line uses one key part
     for the left bound and two key parts for the right bound. The
     interval on the second line uses only one key part. The `key_len'
     column in the *Note `EXPLAIN': explain. output indicates the
     maximum length of the key prefix used.

     In some cases, `key_len' may indicate that a key part was used,
     but that might be not what you would expect. Suppose that
     KEY_PART1 and KEY_PART2 can be `NULL'. Then the `key_len' column
     displays two key part lengths for the following condition:

          KEY_PART1 >= 1 AND KEY_PART2 < 2

     But, in fact, the condition is converted to this:

          KEY_PART1 >= 1 AND KEY_PART2 IS NOT NULL

*Note range-access-single-part::, describes how optimizations are
performed to combine or eliminate intervals for range conditions on a
single-part index. Analogous steps are performed for range conditions
on multiple-part indexes.


File: manual.info,  Node: index-merge-optimization,  Next: condition-pushdown-optimization,  Prev: range-optimization,  Up: query-speed

7.2.6 Index Merge Optimization
------------------------------

* Menu:

* index-merge-intersection::     The Index Merge Intersection Access Algorithm
* index-merge-union::            The Index Merge Union Access Algorithm
* index-merge-sort-union::       The Index Merge Sort-Union Access Algorithm

The _Index Merge_ method is used to retrieve rows with several `range'
scans and to merge their results into one. The merge can produce unions,
intersections, or unions-of-intersections of its underlying scans. This
access method merges index scans from a single table; it does not merge
scans across multiple tables.

In *Note `EXPLAIN': explain. output, the Index Merge method appears as
`index_merge' in the `type' column. In this case, the `key' column
contains a list of indexes used, and `key_len' contains a list of the
longest key parts for those indexes.

Examples:

     SELECT * FROM TBL_NAME WHERE KEY1 = 10 OR KEY2 = 20;

     SELECT * FROM TBL_NAME
       WHERE (KEY1 = 10 OR KEY2 = 20) AND NON_KEY=30;

     SELECT * FROM t1, t2
       WHERE (t1.KEY1 IN (1,2) OR t1.KEY2 LIKE 'VALUE%')
       AND t2.KEY1=t1.SOME_COL;

     SELECT * FROM t1, t2
       WHERE t1.KEY1=1
       AND (t2.KEY1=t1.SOME_COL OR t2.KEY2=t1.SOME_COL2);

The Index Merge method has several access algorithms (seen in the
`Extra' field of *Note `EXPLAIN': explain. output):

   * `Using intersect(...)'

   * `Using union(...)'

   * `Using sort_union(...)'

The following sections describe these methods in greater detail.

*Note*:

The Index Merge optimization algorithm has the following known
deficiencies:

   * If a range scan is possible on some key, the optimizer will not
     consider using Index Merge Union or Index Merge Sort-Union
     algorithms. For example, consider this query:

          SELECT * FROM t1 WHERE (goodkey1 < 10 OR goodkey2 < 20) AND badkey < 30;

     For this query, two plans are possible:

        * An Index Merge scan using the `(goodkey1 < 10 OR goodkey2 <
          20)' condition.

        * A range scan using the `badkey < 30' condition.

     However, the optimizer considers only the second plan.

   * If your query has a complex `WHERE' clause with deep `AND'/`OR'
     nesting and MySQL doesn't choose the optimal plan, try
     distributing terms using the following identity laws:

          (X AND Y) OR Z = (X OR Z) AND (Y OR Z)
          (X OR Y) AND Z = (X AND Z) OR (Y AND Z)

   * Index Merge is not applicable to fulltext indexes. We plan to
     extend it to cover these in a future MySQL release.

The choice between different possible variants of the Index Merge
access method and other access methods is based on cost estimates of
various available options.


File: manual.info,  Node: index-merge-intersection,  Next: index-merge-union,  Prev: index-merge-optimization,  Up: index-merge-optimization

7.2.6.1 The Index Merge Intersection Access Algorithm
.....................................................

This access algorithm can be employed when a `WHERE' clause was
converted to several range conditions on different keys combined with
`AND', and each condition is one of the following:

   * In this form, where the index has exactly N parts (that is, all
     index parts are covered):

          KEY_PART1=CONST1 AND KEY_PART2=CONST2 ... AND KEY_PARTN=CONSTN

   * Any range condition over a primary key of an `InnoDB' table.

Examples:

     SELECT * FROM INNODB_TABLE WHERE PRIMARY_KEY < 10 AND KEY_COL1=20;

     SELECT * FROM TBL_NAME
       WHERE (KEY1_PART1=1 AND KEY1_PART2=2) AND KEY2=2;

The Index Merge intersection algorithm performs simultaneous scans on
all used indexes and produces the intersection of row sequences that it
receives from the merged index scans.

If all columns used in the query are covered by the used indexes, full
table rows are not retrieved (*Note `EXPLAIN': explain. output contains
`Using index' in `Extra' field in this case). Here is an example of
such a query:

     SELECT COUNT(*) FROM t1 WHERE key1=1 AND key2=1;

If the used indexes don't cover all columns used in the query, full
rows are retrieved only when the range conditions for all used keys are
satisfied.

If one of the merged conditions is a condition over a primary key of an
`InnoDB' table, it is not used for row retrieval, but is used to filter
out rows retrieved using other conditions.


File: manual.info,  Node: index-merge-union,  Next: index-merge-sort-union,  Prev: index-merge-intersection,  Up: index-merge-optimization

7.2.6.2 The Index Merge Union Access Algorithm
..............................................

The applicability criteria for this algorithm are similar to those for
the Index Merge method intersection algorithm. The algorithm can be
employed when the table's `WHERE' clause was converted to several range
conditions on different keys combined with `OR', and each condition is
one of the following:

   * In this form, where the index has exactly N parts (that is, all
     index parts are covered):

          KEY_PART1=CONST1 AND KEY_PART2=CONST2 ... AND KEY_PARTN=CONSTN

   * Any range condition over a primary key of an `InnoDB' table.

   * A condition for which the Index Merge method intersection
     algorithm is applicable.

Examples:

     SELECT * FROM t1 WHERE KEY1=1 OR KEY2=2 OR KEY3=3;

     SELECT * FROM INNODB_TABLE WHERE (KEY1=1 AND KEY2=2) OR
       (KEY3='foo' AND KEY4='bar') AND KEY5=5;


File: manual.info,  Node: index-merge-sort-union,  Prev: index-merge-union,  Up: index-merge-optimization

7.2.6.3 The Index Merge Sort-Union Access Algorithm
...................................................

This access algorithm is employed when the `WHERE' clause was converted
to several range conditions combined by `OR', but for which the Index
Merge method union algorithm is not applicable.

Examples:

     SELECT * FROM TBL_NAME WHERE KEY_COL1 < 10 OR KEY_COL2 < 20;

     SELECT * FROM TBL_NAME
       WHERE (KEY_COL1 > 10 OR KEY_COL2 = 20) AND NONKEY_COL=30;

The difference between the sort-union algorithm and the union algorithm
is that the sort-union algorithm must first fetch row IDs for all rows
and sort them before returning any rows.


File: manual.info,  Node: condition-pushdown-optimization,  Next: index-condition-pushdown-optimization,  Prev: index-merge-optimization,  Up: query-speed

7.2.7 Condition Pushdown Optimization
-------------------------------------

This optimization improves the efficiency of a direct comparison
between a non-indexed column and a constant. In such cases, the
condition is `pushed down' to the storage engine for evaluation. In
MySQL 6.0, this optimization can be used only by the `MyISAM' storage
engine; it may be implemented for additional storage engines in future
versions of MySQL.

Suppose that a table is defined as follows:

     CREATE TABLE t1 (
         a INT,
         b INT,
         KEY(a)
     ) ENGINE=MyISAM;

*Note*:

It is not necessary to use an explicit `ENGINE' option to create a
`MyISAM' table if this is the default MySQL storage engine type at the
time the table is created; condition pushdown can still be employed
with such a `MyISAM' table.

Condition pushdown can be used with a query against this table such as
the query shown here:

     SELECT a,b FROM t1 WHERE b = 10;

This can be seen in the output of *Note `EXPLAIN SELECT': explain.:

     mysql> EXPLAIN SELECT a,b FROM t1 WHERE b = 10\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: t1
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: 10
             Extra: Using where with pushed condition

However, condition pushdown _cannot_ be used with either of these two
queries:

     SELECT a,b FROM t1 WHERE a = 10;
     SELECT a,b FROM t1 WHERE b + 1 = 10;

With regard to the first of these two queries, condition pushdown is
not applicable because an index exists on column `a'. (An index access
method would be more efficient and so would be chosen in preference to
condition pushdown.) In the case of the second query, condition pushdown
cannot be employed because the comparison involving the non-indexed
column `b' is indirect. (However, condition pushdown could be applied
if you were to reduce `b + 1 = 10' to `b = 9' in the `WHERE' clause.)

Condition pushdown may also be employed when an indexed column is
compared with a constant using a `>' or `<' operator:

     mysql> EXPLAIN SELECT a,b FROM t1 WHERE a<2\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: t1
              type: range
     possible_keys: a
               key: a
           key_len: 5
               ref: NULL
              rows: 2
             Extra: Using where with pushed condition

Other comparisons which are supported for condition pushdown include
the following:

   * `COLUMN [NOT] LIKE PATTERN'

     PATTERN must be a string literal containing the pattern to be
     matched; for syntax, see *Note string-comparison-functions::.

   * `COLUMN IS [NOT] NULL'

   * `COLUMN IN (VALUE_LIST)'

     Each item in the VALUE_LIST must be a constant, literal value.

   * `COLUMN BETWEEN CONSTANT1 AND CONSTANT2'

     CONSTANT1 and CONSTANT2 must each be a constant, literal value.

In all of the cases in the preceding list, it is possible for the
condition to be converted into the form of one or more direct
comparisons between a column and a constant.

Condition pushdown capability is not used by default. To enable it, you
can start *Note `mysqld': mysqld. with the `--engine-condition-pushdown'
option, or you can execute either of the following statements at
runtime:

     SET engine_condition_pushdown=ON;

     SET engine_condition_pushdown=1;

Limitations

Condition pushdown is subject to the following limitations:

   * In MySQL 6.0, condition pushdown is supported by the `MyISAM'
     storage engine only.

   * Columns may be compared with constants only; however, this
     includes expressions which evaluate to constant values.

   * Columns used in comparisons cannot be of any of the *Note `BLOB':
     blob. or *Note `TEXT': blob. types.

   * A string value to be compared with a column must use the same
     collation as the column.

   * Joins are not directly supported; conditions involving multiple
     tables are pushed separately where possible.  Use `EXPLAIN
     EXTENDED' to determine which conditions are actually pushed down.

*Note*:

The `NDBCLUSTER' storage engine used by MySQL Cluster also supports
condition pushdown; however, this storage engine is currently not
available in MySQL 6.0. If you are interested in using MySQL Cluster,
see MySQL Cluster NDB 6.X/7.X
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html), which
provides information about MySQL Cluster NDB 6.2 and 6.3, which are
based on MySQL 5.1 but contain the latest improvements and fixes for
`NDBCLUSTER'.


File: manual.info,  Node: index-condition-pushdown-optimization,  Next: is-null-optimization,  Prev: condition-pushdown-optimization,  Up: query-speed

7.2.8 Index Condition Pushdown Optimization
-------------------------------------------

Index Condition Pushdown optimization is used for the `range', `ref',
`eq_ref', and `ref_or_null' access methods when there is a need to
access full table rows. The optimization is that the server tries to
use index information to defer (`push down') reading of full table rows
unless it is known to be necessary. This is done by performing early
tests on index tuples first. This strategy can be used for `MyISAM'
tables.

To see how this optimization works, consider first how an index scan
proceeds when Index Condition Pushdown is not used:

  1. Get the next row, first by reading the index tuple, and then by
     using the index tuple to locate and read the full table row.

  2. Test the part of the `WHERE' condition that applies to this table.
     Accept or reject the row based on the test result.

When Index Condition Pushdown is used, the scan proceeds like this
instead:

  1. Get the next rows's index tuple (but not the full table row).

  2. Test the part of the `WHERE' condition that applies to this table
     and can be checked using only index columns. If the condition is
     not satisfied, proceed to the next row.

  3. Use the index tuple to locate and read the full table row.

  4. Test the part of the `WHERE' condition that applies to this table.
     Accept or reject the row based on the test result.

When Index Condition Pushdown is used, the `Extra' column in *Note
`EXPLAIN': explain. output shows `Using index condition'. It will not
show `Index only' because that does not apply when full table rows must
be read.

Suppose that we have a table containing information about people and
their addresses and that the table has an index defined as `INDEX
(zipcode, lastname, firstname)'. If we know a person's `zipcode' value
but are not sure about the last name, we can search like this:

     SELECT * FROM people
       WHERE zipcode='95054'
       AND lastname LIKE '%etrunia%'
       AND address LIKE '%Main Street%'

MySQL can use the index to scan through people with `zipcode='95054''.
The second part (`lastname LIKE '%etrunia%'') cannot be used to limit
the number of rows that must be scanned, so without Index Condition
Pushdown, this query must retrieve full table rows for all the people
who have `zipcode='95054''.

With Index Condition Pushdown, MySQL will check the `lastname LIKE
'%etrunia%'' part before reading the full table row. This avoids
reading full rows corresponding to all index tuples that do not match
the `lastname' condition. The full-row test is `pushed down' to take
place later than the index-only test.

Index Condition Pushdown is enabled by default; it can be controlled
with the `engine_condition_pushdown' system variable. This variable
also controls table Condition Pushdown as used for NDB; see *Note
condition-pushdown-optimization::.


File: manual.info,  Node: is-null-optimization,  Next: left-join-optimization,  Prev: index-condition-pushdown-optimization,  Up: query-speed

7.2.9 `IS NULL' Optimization
----------------------------

MySQL can perform the same optimization on COL_NAME `IS NULL' that it
can use for COL_NAME `=' CONSTANT_VALUE. For example, MySQL can use
indexes and ranges to search for `NULL' with `IS NULL'.

Examples:

     SELECT * FROM TBL_NAME WHERE KEY_COL IS NULL;

     SELECT * FROM TBL_NAME WHERE KEY_COL <=> NULL;

     SELECT * FROM TBL_NAME
       WHERE KEY_COL=CONST1 OR KEY_COL=CONST2 OR KEY_COL IS NULL;

If a `WHERE' clause includes a COL_NAME `IS NULL' condition for a
column that is declared as `NOT NULL', that expression is optimized
away.  This optimization does not occur in cases when the column might
produce `NULL' anyway; for example, if it comes from a table on the
right side of a `LEFT JOIN'.

MySQL can also optimize the combination `COL_NAME = EXPR OR COL_NAME IS
NULL', a form that is common in resolved subqueries.  *Note `EXPLAIN':
explain. shows `ref_or_null' when this optimization is used.

This optimization can handle one `IS NULL' for any key part.

Some examples of queries that are optimized, assuming that there is an
index on columns `a' and `b' of table `t2':

     SELECT * FROM t1 WHERE t1.a=EXPR OR t1.a IS NULL;

     SELECT * FROM t1, t2 WHERE t1.a=t2.a OR t2.a IS NULL;

     SELECT * FROM t1, t2
       WHERE (t1.a=t2.a OR t2.a IS NULL) AND t2.b=t1.b;

     SELECT * FROM t1, t2
       WHERE t1.a=t2.a AND (t2.b=t1.b OR t2.b IS NULL);

     SELECT * FROM t1, t2
       WHERE (t1.a=t2.a AND t2.a IS NULL AND ...)
       OR (t1.a=t2.a AND t2.a IS NULL AND ...);

`ref_or_null' works by first doing a read on the reference key, and
then a separate search for rows with a `NULL' key value.

Note that the optimization can handle only one `IS NULL' level. In the
following query, MySQL uses key lookups only on the expression
`(t1.a=t2.a AND t2.a IS NULL)' and is not able to use the key part on
`b':

     SELECT * FROM t1, t2
       WHERE (t1.a=t2.a AND t2.a IS NULL)
       OR (t1.b=t2.b AND t2.b IS NULL);


File: manual.info,  Node: left-join-optimization,  Next: nested-loop-joins,  Prev: is-null-optimization,  Up: query-speed

7.2.10 `LEFT JOIN' and `RIGHT JOIN' Optimization
------------------------------------------------

MySQL implements an `A LEFT JOIN B join_condition' as follows:

   * Table B is set to depend on table A and all tables on which A
     depends.

   * Table A is set to depend on all tables (except B) that are used in
     the `LEFT JOIN' condition.

   * The `LEFT JOIN' condition is used to decide how to retrieve rows
     from table B. (In other words, any condition in the `WHERE' clause
     is not used.)

   * All standard join optimizations are performed, with the exception
     that a table is always read after all tables on which it depends.
     If there is a circular dependence, MySQL issues an error.

   * All standard `WHERE' optimizations are performed.

   * If there is a row in A that matches the `WHERE' clause, but there
     is no row in B that matches the `ON' condition, an extra B row is
     generated with all columns set to `NULL'.

   * If you use `LEFT JOIN' to find rows that do not exist in some
     table and you have the following test: `COL_NAME IS NULL' in the
     `WHERE' part, where COL_NAME is a column that is declared as `NOT
     NULL', MySQL stops searching for more rows (for a particular key
     combination) after it has found one row that matches the `LEFT
     JOIN' condition.

The implementation of `RIGHT JOIN' is analogous to that of `LEFT JOIN'
with the roles of the tables reversed.

The join optimizer calculates the order in which tables should be
joined. The table read order forced by `LEFT JOIN' or `STRAIGHT_JOIN'
helps the join optimizer do its work much more quickly, because there
are fewer table permutations to check. Note that this means that if you
do a query of the following type, MySQL does a full scan on `b' because
the `LEFT JOIN' forces it to be read before `d':

     SELECT *
       FROM a JOIN b LEFT JOIN c ON (c.key=a.key)
       LEFT JOIN d ON (d.key=a.key)
       WHERE b.key=d.key;

The fix in this case is reverse the order in which `a' and `b' are
listed in the `FROM' clause:

     SELECT *
       FROM b JOIN a LEFT JOIN c ON (c.key=a.key)
       LEFT JOIN d ON (d.key=a.key)
       WHERE b.key=d.key;

For a `LEFT JOIN', if the `WHERE' condition is always false for the
generated `NULL' row, the `LEFT JOIN' is changed to a normal join. For
example, the `WHERE' clause would be false in the following query if
`t2.column1' were `NULL':

     SELECT * FROM t1 LEFT JOIN t2 ON (column1) WHERE t2.column2=5;

Therefore, it is safe to convert the query to a normal join:

     SELECT * FROM t1, t2 WHERE t2.column2=5 AND t1.column1=t2.column1;

This can be made faster because MySQL can use table `t2' before table
`t1' if doing so would result in a better query plan. To provide a hint
about the table join order, use `STRAIGHT_JOIN'. (See *Note select::.)


File: manual.info,  Node: nested-loop-joins,  Next: nested-join-optimization,  Prev: left-join-optimization,  Up: query-speed

7.2.11 Nested-Loop Join Algorithms
----------------------------------

MySQL executes joins between tables using a nested-loop algorithm or
variations on it.

*Nested-Loop Join Algorithm*

A simple nested-loop join (NLJ) algorithm reads rows from the first
table in a loop one at a time, passing each row to a nested loop that
processes the next table in the join. This process is repeated as many
times as there remain tables to be joined.

Assume that a join between three tables `t1', `t2', and `t3' is to be
executed using the following join types:

     Table   Join Type
     t1      range
     t2      ref
     t3      ALL

If a simple NLJ algorithm is used, the join would be processed like
this:

     for each row in t1 matching range {
       for each row in t2 matching reference key {
         for each row in t3 {
           if row satisfies join conditions,
           send to client
         }
       }
     }

Because the NLJ algorithm passes rows one at a time from outer loops to
inner loops, tables processed in the inner loops typically are read
many times.

*Block Nested-Loop Join Algorithm*

A Block Nested-Loop (BNL) Join algorithm uses buffering of rows read in
outer loops to reduce the number of times that tables in inner loops
must be read. For example, if 10 rows are read into a buffer and the
buffer is passed to the next inner loop, each row read in the inner
loop can be compared against all 10 rows in the buffer. The reduces the
number of times the inner table must be read by an order of magnitude.

MySQL uses join buffering under these conditions:

   * The `join_buffer_size' system variable determines the size of each
     join buffer.

   * Join buffering can be used when the join is of type `ALL' or
     `index' (in other words, when no possible keys can be used, and a
     full scan is done, of either the data or index rows,
     respectively), or `range'. As of MySQL 6.0.9, use of buffering is
     extended to be applicable to outer joins and semi-joins, as
     described in *Note bnl-bka-optimization::.

   * One buffer is allocated for each join that can be buffered, so a
     given query might be processed using multiple join buffers.

   * A join buffer is never allocated for the first non-const table,
     even if it would be of type `ALL' or `index'.

   * A join buffer is allocated prior to executing the join and freed
     after the query is done.

   * Only columns of interest to the join are stored in the join
     buffer, not whole rows.

For the example join described previously for the NLJ algorithm
(without buffering), the join would be done as follow using join
buffering:

     for each row in t1 matching range {
       for each row in t2 matching reference key {
         store used columns from t1, t2 in join buffer
         if buffer is full {
           for each row in t3 {
             for each t1, t2 combination in join buffer {
               if row satisfies join conditions,
               send to client
             }
           }
           empty buffer
         }
       }
     }

     if buffer is not empty {
       for each row in t3 {
         for each t1, t2 combination in join buffer {
           if row satisfies join conditions,
           send to client
         }
       }
     }

If S is the size of each stored `t1', `t2' combination is the join
buffer and C is the number of combinations in the buffer, the number of
times table `t3' is scanned is:

     (S * C)/join_buffer_size + 1

One implication is that the number of `t3' scans decreases as the value
of `join_buffer_size' increases, up to the point when
`join_buffer_size' is large enough to hold all previous row
combinations. At that point, there is no speed to be gained by making
it larger.


File: manual.info,  Node: nested-join-optimization,  Next: outer-join-simplification,  Prev: nested-loop-joins,  Up: query-speed

7.2.12 Nested Join Optimization
-------------------------------

The syntax for expressing joins allows nested joins. The following
discussion refers to the join syntax described in *Note join::.

The syntax of TABLE_FACTOR is extended in comparison with the SQL
Standard. The latter accepts only TABLE_REFERENCE, not a list of them
inside a pair of parentheses. This is a conservative extension if we
consider each comma in a list of TABLE_REFERENCE items as equivalent to
an inner join. For example:

     SELECT * FROM t1 LEFT JOIN (t2, t3, t4)
                      ON (t2.a=t1.a AND t3.b=t1.b AND t4.c=t1.c)

is equivalent to:

     SELECT * FROM t1 LEFT JOIN (t2 CROSS JOIN t3 CROSS JOIN t4)
                      ON (t2.a=t1.a AND t3.b=t1.b AND t4.c=t1.c)

In MySQL, `CROSS JOIN' is a syntactic equivalent to `INNER JOIN' (they
can replace each other). In standard SQL, they are not equivalent.
`INNER JOIN' is used with an `ON' clause; `CROSS JOIN' is used
otherwise.

In general, parentheses can be ignored in join expressions containing
only inner join operations. After removing parentheses and grouping
operations to the left, the join expression:

     t1 LEFT JOIN (t2 LEFT JOIN t3 ON t2.b=t3.b OR t2.b IS NULL)
        ON t1.a=t2.a

transforms into the expression:

     (t1 LEFT JOIN t2 ON t1.a=t2.a) LEFT JOIN t3
         ON t2.b=t3.b OR t2.b IS NULL

Yet, the two expressions are not equivalent. To see this, suppose that
the tables `t1', `t2', and `t3' have the following state:

   * Table `t1' contains rows `(1)', `(2)'

   * Table `t2' contains row `(1,101)'

   * Table `t3' contains row `(101)'

In this case, the first expression returns a result set including the
rows `(1,1,101,101)', `(2,NULL,NULL,NULL)', whereas the second
expression returns the rows `(1,1,101,101)', `(2,NULL,NULL,101)':

     mysql> SELECT *
         -> FROM t1
         ->      LEFT JOIN
         ->      (t2 LEFT JOIN t3 ON t2.b=t3.b OR t2.b IS NULL)
         ->      ON t1.a=t2.a;
     +------+------+------+------+
     | a    | a    | b    | b    |
     +------+------+------+------+
     |    1 |    1 |  101 |  101 |
     |    2 | NULL | NULL | NULL |
     +------+------+------+------+

     mysql> SELECT *
         -> FROM (t1 LEFT JOIN t2 ON t1.a=t2.a)
         ->      LEFT JOIN t3
         ->      ON t2.b=t3.b OR t2.b IS NULL;
     +------+------+------+------+
     | a    | a    | b    | b    |
     +------+------+------+------+
     |    1 |    1 |  101 |  101 |
     |    2 | NULL | NULL |  101 |
     +------+------+------+------+

In the following example, an outer join operation is used together with
an inner join operation:

     t1 LEFT JOIN (t2, t3) ON t1.a=t2.a

That expression cannot be transformed into the following expression:

     t1 LEFT JOIN t2 ON t1.a=t2.a, t3.

For the given table states, the two expressions return different sets
of rows:

     mysql> SELECT *
         -> FROM t1 LEFT JOIN (t2, t3) ON t1.a=t2.a;
     +------+------+------+------+
     | a    | a    | b    | b    |
     +------+------+------+------+
     |    1 |    1 |  101 |  101 |
     |    2 | NULL | NULL | NULL |
     +------+------+------+------+

     mysql> SELECT *
         -> FROM t1 LEFT JOIN t2 ON t1.a=t2.a, t3;
     +------+------+------+------+
     | a    | a    | b    | b    |
     +------+------+------+------+
     |    1 |    1 |  101 |  101 |
     |    2 | NULL | NULL |  101 |
     +------+------+------+------+

Therefore, if we omit parentheses in a join expression with outer join
operators, we might change the result set for the original expression.

More exactly, we cannot ignore parentheses in the right operand of the
left outer join operation and in the left operand of a right join
operation. In other words, we cannot ignore parentheses for the inner
table expressions of outer join operations. Parentheses for the other
operand (operand for the outer table) can be ignored.

The following expression:

     (t1,t2) LEFT JOIN t3 ON P(t2.b,t3.b)

is equivalent to this expression:

     t1, t2 LEFT JOIN t3 ON P(t2.b,t3.b)

for any tables `t1,t2,t3' and any condition `P' over attributes `t2.b'
and `t3.b'.

Whenever the order of execution of the join operations in a join
expression (JOIN_TABLE) is not from left to right, we talk about nested
joins. Consider the following queries:

     SELECT * FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t2.b=t3.b) ON t1.a=t2.a
       WHERE t1.a > 1

     SELECT * FROM t1 LEFT JOIN (t2, t3) ON t1.a=t2.a
       WHERE (t2.b=t3.b OR t2.b IS NULL) AND t1.a > 1

Those queries are considered to contain these nested joins:

     t2 LEFT JOIN t3 ON t2.b=t3.b
     t2, t3

The nested join is formed in the first query with a left join
operation, whereas in the second query it is formed with an inner join
operation.

In the first query, the parentheses can be omitted: The grammatical
structure of the join expression will dictate the same order of
execution for join operations. For the second query, the parentheses
cannot be omitted, although the join expression here can be interpreted
unambiguously without them.  (In our extended syntax the parentheses in
`(t2, t3)' of the second query are required, although theoretically the
query could be parsed without them: We still would have unambiguous
syntactical structure for the query because `LEFT JOIN' and `ON' would
play the role of the left and right delimiters for the expression
`(t2,t3)'.)

The preceding examples demonstrate these points:

   * For join expressions involving only inner joins (and not outer
     joins), parentheses can be removed. You can remove parentheses and
     evaluate left to right (or, in fact, you can evaluate the tables
     in any order).

   * The same is not true, in general, for outer joins or for outer
     joins mixed with inner joins. Removal of parentheses may change
     the result.

Queries with nested outer joins are executed in the same pipeline
manner as queries with inner joins. More exactly, a variation of the
nested-loop join algorithm is exploited. Recall by what algorithmic
schema the nested-loop join executes a query. Suppose that we have a
join query over 3 tables `T1,T2,T3' of the form:

     SELECT * FROM T1 INNER JOIN T2 ON P1(T1,T2)
                      INNER JOIN T3 ON P2(T2,T3)
       WHERE P(T1,T2,T3).

Here, `P1(T1,T2)' and `P2(T3,T3)' are some join conditions (on
expressions), whereas `P(t1,t2,t3)' is a condition over columns of
tables `T1,T2,T3'.

The nested-loop join algorithm would execute this query in the
following manner:

     FOR each row t1 in T1 {
       FOR each row t2 in T2 such that P1(t1,t2) {
         FOR each row t3 in T3 such that P2(t2,t3) {
           IF P(t1,t2,t3) {
              t:=t1||t2||t3; OUTPUT t;
           }
         }
       }
     }

The notation `t1||t2||t3' means `a row constructed by concatenating the
columns of rows `t1', `t2', and `t3'.' In some of the following
examples, `NULL' where a row name appears means that `NULL' is used for
each column of that row. For example, `t1||t2||NULL' means `a row
constructed by concatenating the columns of rows `t1' and `t2', and
`NULL' for each column of `t3'.'

Now let's consider a query with nested outer joins:

     SELECT * FROM T1 LEFT JOIN
                   (T2 LEFT JOIN T3 ON P2(T2,T3))
                   ON P1(T1,T2)
       WHERE P(T1,T2,T3).

For this query, we modify the nested-loop pattern to get:

     FOR each row t1 in T1 {
       BOOL f1:=FALSE;
       FOR each row t2 in T2 such that P1(t1,t2) {
         BOOL f2:=FALSE;
         FOR each row t3 in T3 such that P2(t2,t3) {
           IF P(t1,t2,t3) {
             t:=t1||t2||t3; OUTPUT t;
           }
           f2=TRUE;
           f1=TRUE;
         }
         IF (!f2) {
           IF P(t1,t2,NULL) {
             t:=t1||t2||NULL; OUTPUT t;
           }
           f1=TRUE;
         }
       }
       IF (!f1) {
         IF P(t1,NULL,NULL) {
           t:=t1||NULL||NULL; OUTPUT t;
         }
       }
     }

In general, for any nested loop for the first inner table in an outer
join operation, a flag is introduced that is turned off before the loop
and is checked after the loop. The flag is turned on when for the
current row from the outer table a match from the table representing
the inner operand is found. If at the end of the loop cycle the flag is
still off, no match has been found for the current row of the outer
table. In this case, the row is complemented by `NULL' values for the
columns of the inner tables. The result row is passed to the final
check for the output or into the next nested loop, but only if the row
satisfies the join condition of all embedded outer joins.

In our example, the outer join table expressed by the following
expression is embedded:

     (T2 LEFT JOIN T3 ON P2(T2,T3))

Note that for the query with inner joins, the optimizer could choose a
different order of nested loops, such as this one:

     FOR each row t3 in T3 {
       FOR each row t2 in T2 such that P2(t2,t3) {
         FOR each row t1 in T1 such that P1(t1,t2) {
           IF P(t1,t2,t3) {
              t:=t1||t2||t3; OUTPUT t;
           }
         }
       }
     }

For the queries with outer joins, the optimizer can choose only such an
order where loops for outer tables precede loops for inner tables.
Thus, for our query with outer joins, only one nesting order is
possible. For the following query, the optimizer will evaluate two
different nestings:

     SELECT * T1 LEFT JOIN (T2,T3) ON P1(T1,T2) AND P2(T1,T3)
       WHERE P(T1,T2,T3)

The nestings are these:

     FOR each row t1 in T1 {
       BOOL f1:=FALSE;
       FOR each row t2 in T2 such that P1(t1,t2) {
         FOR each row t3 in T3 such that P2(t1,t3) {
           IF P(t1,t2,t3) {
             t:=t1||t2||t3; OUTPUT t;
           }
           f1:=TRUE
         }
       }
       IF (!f1) {
         IF P(t1,NULL,NULL) {
           t:=t1||NULL||NULL; OUTPUT t;
         }
       }
     }

and:

     FOR each row t1 in T1 {
       BOOL f1:=FALSE;
       FOR each row t3 in T3 such that P2(t1,t3) {
         FOR each row t2 in T2 such that P1(t1,t2) {
           IF P(t1,t2,t3) {
             t:=t1||t2||t3; OUTPUT t;
           }
           f1:=TRUE
         }
       }
       IF (!f1) {
         IF P(t1,NULL,NULL) {
           t:=t1||NULL||NULL; OUTPUT t;
         }
       }
     }

In both nestings, `T1' must be processed in the outer loop because it
is used in an outer join.  `T2' and `T3' are used in an inner join, so
that join must be processed in the inner loop.  However, because the
join is an inner join, `T2' and `T3' can be processed in either order.

When discussing the nested-loop algorithm for inner joins, we omitted
some details whose impact on the performance of query execution may be
huge. We did not mention so-called `pushed-down' conditions. Suppose
that our `WHERE' condition `P(T1,T2,T3)' can be represented by a
conjunctive formula:

     P(T1,T2,T2) = C1(T1) AND C2(T2) AND C3(T3).

In this case, MySQL actually uses the following nested-loop schema for
the execution of the query with inner joins:

     FOR each row t1 in T1 such that C1(t1) {
       FOR each row t2 in T2 such that P1(t1,t2) AND C2(t2)  {
         FOR each row t3 in T3 such that P2(t2,t3) AND C3(t3) {
           IF P(t1,t2,t3) {
              t:=t1||t2||t3; OUTPUT t;
           }
         }
       }
     }

You see that each of the conjuncts `C1(T1)', `C2(T2)', `C3(T3)' are
pushed out of the most inner loop to the most outer loop where it can
be evaluated. If `C1(T1)' is a very restrictive condition, this
condition pushdown may greatly reduce the number of rows from table
`T1' passed to the inner loops. As a result, the execution time for the
query may improve immensely.

For a query with outer joins, the `WHERE' condition is to be checked
only after it has been found that the current row from the outer table
has a match in the inner tables. Thus, the optimization of pushing
conditions out of the inner nested loops cannot be applied directly to
queries with outer joins. Here we have to introduce conditional
pushed-down predicates guarded by the flags that are turned on when a
match has been encountered.

For our example with outer joins with:

     P(T1,T2,T3)=C1(T1) AND C(T2) AND C3(T3)

the nested-loop schema using guarded pushed-down conditions looks like
this:

     FOR each row t1 in T1 such that C1(t1) {
       BOOL f1:=FALSE;
       FOR each row t2 in T2
           such that P1(t1,t2) AND (f1?C2(t2):TRUE) {
         BOOL f2:=FALSE;
         FOR each row t3 in T3
             such that P2(t2,t3) AND (f1&&f2?C3(t3):TRUE) {
           IF (f1&&f2?TRUE:(C2(t2) AND C3(t3))) {
             t:=t1||t2||t3; OUTPUT t;
           }
           f2=TRUE;
           f1=TRUE;
         }
         IF (!f2) {
           IF (f1?TRUE:C2(t2) && P(t1,t2,NULL)) {
             t:=t1||t2||NULL; OUTPUT t;
           }
           f1=TRUE;
         }
       }
       IF (!f1 && P(t1,NULL,NULL)) {
           t:=t1||NULL||NULL; OUTPUT t;
       }
     }

In general, pushed-down predicates can be extracted from join
conditions such as `P1(T1,T2)' and `P(T2,T3)'. In this case, a
pushed-down predicate is guarded also by a flag that prevents checking
the predicate for the `NULL'-complemented row generated by the
corresponding outer join operation.

Note that access by key from one inner table to another in the same
nested join is prohibited if it is induced by a predicate from the
`WHERE' condition. (We could use conditional key access in this case,
but this technique is not employed yet in MySQL 6.0.)


File: manual.info,  Node: outer-join-simplification,  Next: mrr-optimization,  Prev: nested-join-optimization,  Up: query-speed

7.2.13 Outer Join Simplification
--------------------------------

Table expressions in the `FROM' clause of a query are simplified in
many cases.

At the parser stage, queries with right outer joins operations are
converted to equivalent queries containing only left join operations.
In the general case, the conversion is performed according to the
following rule:

     (T1, ...) RIGHT JOIN (T2,...) ON P(T1,...,T2,...) =
     (T2, ...) LEFT JOIN (T1,...) ON P(T1,...,T2,...)

All inner join expressions of the form `T1 INNER JOIN T2 ON P(T1,T2)'
are replaced by the list `T1,T2', `P(T1,T2)' being joined as a conjunct
to the `WHERE' condition (or to the join condition of the embedding
join, if there is any).

When the optimizer evaluates plans for join queries with outer join
operation, it takes into consideration only the plans where, for each
such operation, the outer tables are accessed before the inner tables.
The optimizer options are limited because only such plans enables us to
execute queries with outer joins operations by the nested loop schema.

Suppose that we have a query of the form:

     SELECT * T1 LEFT JOIN T2 ON P1(T1,T2)
       WHERE P(T1,T2) AND R(T2)

with `R(T2)' narrowing greatly the number of matching rows from table
`T2'. If we executed the query as it is, the optimizer would have no
other choice besides to access table `T1' before table `T2' that may
lead to a very inefficient execution plan.

Fortunately, MySQL converts such a query into a query without an outer
join operation if the `WHERE' condition is null-rejected. A condition
is called null-rejected for an outer join operation if it evaluates to
`FALSE' or to `UNKNOWN' for any `NULL'-complemented row built for the
operation.

Thus, for this outer join:

     T1 LEFT JOIN T2 ON T1.A=T2.A

Conditions such as these are null-rejected:

     T2.B IS NOT NULL,
     T2.B > 3,
     T2.C <= T1.C,
     T2.B < 2 OR T2.C > 1

Conditions such as these are not null-rejected:

     T2.B IS NULL,
     T1.B < 3 OR T2.B IS NOT NULL,
     T1.B < 3 OR T2.B > 3

The general rules for checking whether a condition is null-rejected for
an outer join operation are simple. A condition is null-rejected in the
following cases:

   * If it is of the form `A IS NOT NULL', where `A' is an attribute of
     any of the inner tables

   * If it is a predicate containing a reference to an inner table that
     evaluates to `UNKNOWN' when one of its arguments is `NULL'

   * If it is a conjunction containing a null-rejected condition as a
     conjunct

   * If it is a disjunction of null-rejected conditions

A condition can be null-rejected for one outer join operation in a
query and not null-rejected for another. In the query:

     SELECT * FROM T1 LEFT JOIN T2 ON T2.A=T1.A
                      LEFT JOIN T3 ON T3.B=T1.B
       WHERE T3.C > 0

the `WHERE' condition is null-rejected for the second outer join
operation but is not null-rejected for the first one.

If the `WHERE' condition is null-rejected for an outer join operation
in a query, the outer join operation is replaced by an inner join
operation.

For example, the preceding query is replaced with the query:

     SELECT * FROM T1 LEFT JOIN T2 ON T2.A=T1.A
                      INNER JOIN T3 ON T3.B=T1.B
       WHERE T3.C > 0

For the original query, the optimizer would evaluate plans compatible
with only one access order `T1,T2,T3'. For the replacing query, it
additionally considers the access sequence `T3,T1,T2'.

A conversion of one outer join operation may trigger a conversion of
another. Thus, the query:

     SELECT * FROM T1 LEFT JOIN T2 ON T2.A=T1.A
                      LEFT JOIN T3 ON T3.B=T2.B
       WHERE T3.C > 0

will be first converted to the query:

     SELECT * FROM T1 LEFT JOIN T2 ON T2.A=T1.A
                      INNER JOIN T3 ON T3.B=T2.B
       WHERE T3.C > 0

which is equivalent to the query:

     SELECT * FROM (T1 LEFT JOIN T2 ON T2.A=T1.A), T3
       WHERE T3.C > 0 AND T3.B=T2.B

Now the remaining outer join operation can be replaced by an inner
join, too, because the condition `T3.B=T2.B' is null-rejected and we
get a query without outer joins at all:

     SELECT * FROM (T1 INNER JOIN T2 ON T2.A=T1.A), T3
       WHERE T3.C > 0 AND T3.B=T2.B

Sometimes we succeed in replacing an embedded outer join operation, but
cannot convert the embedding outer join. The following query:

     SELECT * FROM T1 LEFT JOIN
                   (T2 LEFT JOIN T3 ON T3.B=T2.B)
                   ON T2.A=T1.A
       WHERE T3.C > 0

is converted to:

     SELECT * FROM T1 LEFT JOIN
                   (T2 INNER JOIN T3 ON T3.B=T2.B)
                   ON T2.A=T1.A
       WHERE T3.C > 0,

That can be rewritten only to the form still containing the embedding
outer join operation:

     SELECT * FROM T1 LEFT JOIN
                   (T2,T3)
                   ON (T2.A=T1.A AND T3.B=T2.B)
       WHERE T3.C > 0.

When trying to convert an embedded outer join operation in a query, we
must take into account the join condition for the embedding outer join
together with the `WHERE' condition. In the query:

     SELECT * FROM T1 LEFT JOIN
                   (T2 LEFT JOIN T3 ON T3.B=T2.B)
                   ON T2.A=T1.A AND T3.C=T1.C
       WHERE T3.D > 0 OR T1.D > 0

the `WHERE' condition is not null-rejected for the embedded outer join,
but the join condition of the embedding outer join `T2.A=T1.A AND
T3.C=T1.C' is null-rejected. So the query can be converted to:

     SELECT * FROM T1 LEFT JOIN
                   (T2, T3)
                   ON T2.A=T1.A AND T3.C=T1.C AND T3.B=T2.B
       WHERE T3.D > 0 OR T1.D > 0


File: manual.info,  Node: mrr-optimization,  Next: bnl-bka-optimization,  Prev: outer-join-simplification,  Up: query-speed

7.2.14 Multi-Range Read Optimization
------------------------------------

The Multi-Range Read (MRR) optimization provides these benefits:

   * MRR enables data rows to be accessed sequentially rather than in
     random order, based on index tuples. The server obtains a set of
     index tuples that satisfy the query conditions, sorts them
     according to data row ID order, and uses the sorted tuples to
     retrieve data rows in order. This makes data access more efficient
     and less expensive.

   * MRR enables batch processing of requests for key access for
     operations that require access to data rows via index tuples, such
     as range index scans and equi-joins that use an index for the join
     attribute. MRR iterates over a sequence of index ranges to obtain
     qualifying index tuples. As these results accumulate, they are
     used to access the corresponding data rows. It is not necessary to
     acquire all index tuples before starting to read data rows.

The following scenarios illustrate when MRR optimization can be
advantageous:

Scenario A: MRR can be used for `MyISAM' tables for index range scans
and equi-join operations.

  1. A portion of the index tuples are accumulated in a buffer.

  2. The tuples in the buffer are sorted by their data row ID.

  3. Data rows are accessed according to the sorted index tuple
     sequence.

Scenario B: MRR can be used for `NDB' tables for multiple-range index
scans or when performing an equi-join by an attribute.

  1. A portion of ranges, possibly single-key ranges, is accumulated in
     a buffer on the central node where the query is submitted.

  2. The ranges are sent to the execution nodes that access data rows.

  3. The accessed rows are packed into packages and sent back to the
     central node.

  4. The received packages with data rows are placed in a buffer.

  5. Data rows are read from the buffer.

When MRR is used, the `Extra' column in *Note `EXPLAIN': explain.
output shows `Using MRR'.

`MyISAM' does not use MRR if full table rows need not be accessed to
produce the query result. This is the case if results can be produced
entirely on the basis on information in the index tuples; MRR provides
no benefit.

Example query for which MRR can be used, assuming that there is an
index on `(KEY_PART1, KEY_PART2)':

     SELECT * FROM t
       WHERE KEY_PART1 >= 1000 AND KEY_PART1 < 2000
       AND KEY_PART2 = 10000;

The index consists of tuples of `(KEY_PART1, KEY_PART2)' values, ordered
first by KEY_PART1 and then by KEY_PART2.

Without MRR, an index scan covers all index tuples for the KEY_PART1
range from 1000 up to 2000, regardless of the KEY_PART2 value in these
tuples. The scan does extra work to the extent that tuples in the range
contain KEY_PART2 values other than 10000.

With MRR, the scan is broken up into multiple ranges, each for a single
value of KEY_PART1 (1000, 1001, ... , 1999). Each of these scans need
look only for tuples with KEY_PART2 = 10000. If the index contains many
tuples for which KEY_PART2 is not 10000, MRR results in many fewer
index tuples being read.

To express this using interval notation, the non-MRR scan must examine
the index range `[{1000, 10000}, {2000, MIN_INT})', which may include
many tuples other than those for which KEY_PART2 = 10000.  The MRR scan
examines multiple single-point intervals `[{1000, 10000}]', ...,
`[{1999, 10000}]', which includes only tuples with KEY_PART2 = 10000.

The `optimizer_use_mrr' system variable provides an interface to the
use of MRR optimization.  It has supported values of `force' and
`disable'. The default value is `force'. That is, MRR is used whenever
it is applicable.

For MRR, a storage engine uses the value of the `read_rnd_buffer_size'
system variable as a guideline for how much memory it can allocate for
its buffer. The engine uses up to `read_rnd_buffer_size' bytes and
determines the number of ranges to process in a single pass.


File: manual.info,  Node: bnl-bka-optimization,  Next: order-by-optimization,  Prev: mrr-optimization,  Up: query-speed

7.2.15 Block Nested-Loop and Batched Key Access Joins
-----------------------------------------------------

* Menu:

* join-buffer-management::       Join Buffer Management for Block Nested-Loop and Batched Key Access Algorithms
* bnl-optimization::             Block Nested-Loop Algorithm for Outer Joins and Semi-Joins
* bka-optimization::             Batched Key Access Joins

Starting from MySQL 6.0.9, a new algorithm that uses both index access
to the joined table and a join buffer has been implemented. It is
called the Batched Key Access (BKA) Join algorithm. The algorithm
supports inner join, outer join and semi-join operations, including
nested outer joins and nested semi-joins. Also, the Block Nested-Loop
(BNL) Join algorithm previously used only for inner joins has been
extended and can be employed for outer join and semi-join operations,
including nested outer joins and nested semi-joins.

For BKA, benefits include improved join performance for `NDBCLUSTER'
due to a reduced number of round trips, and for disk-based storage
engines such as `MyISAM', `InnoDB', `Falcon', and `Maria' due to more
efficient table scanning.

The following sections discuss the new join buffer management that
underlies the reimplementation of the original BNL algorithm, the
extended BNL algorithm, the BKA algorithm, and describe how these
algorithms operate.


File: manual.info,  Node: join-buffer-management,  Next: bnl-optimization,  Prev: bnl-bka-optimization,  Up: bnl-bka-optimization

7.2.15.1 Join Buffer Management for Block Nested-Loop and Batched Key Access Algorithms
.......................................................................................

Starting from version 6.0.9, MySQL Server can employ join buffers to
execute not only inner joins without index access to the inner table,
but also outer joins and semi-joins that appear after subquery
flattening. Moreover, a join buffer now can be effectively used when
there is an index access to the inner table.

The new join buffer management code slightly more efficiently utilizes
join buffer space when storing the values of the interesting row
columns: No additional bytes are allocated in buffers for a row column
if its value is `NULL', and the minimum number of bytes is allocated
for any value of the *Note `VARCHAR': char. type.

The new code supports two types of buffers, regular and incremental.
Suppose that join buffer `B1' is employed to join tables `t1' and `t2'
and the result of this operation is joined with table `t3' using join
buffer `B2':

   * A regular join buffer contains columns from each join operand. If
     `B2' is a regular join buffer, each row R put into `B2' is
     composed of the columns of a row R1 from `B1' and the interesting
     columns of a matching row R2 from table `t2'.

   * An incremental join buffer contains only columns from rows of the
     table produced by the second join operand. That is, it is
     incremental to a row from the first operand buffer.  If `B2' is an
     incremental join buffer, the interesting columns of the row R2 are
     stored with a link to the row R1 from `B1'.

Incremental join buffers are always incremental relative to a join
buffer from an earlier join operation, so the buffer from the first
join operation is always a regular buffer. In the example just given,
the buffer `B1' used to join tables `t1' and `t2' must be a regular
buffer.

Each row of the incremental buffer used for a join operation contains
only the interesting columns of a row from the table to be joined.
These columns are augmented with a reference to the interesting columns
of the matched row from the table produced by the first join operand.
Several rows in the incremental buffer can refer to the same row R
whose columns are stored in the previous join buffers insofar as all
these rows match row R.

Incremental buffers enable less frequent copying of columns from
buffers used for previous join operations. This provides a savings in
buffer space because in the general case a row produced by the first
join operand can be matched by several rows produced by the second join
operand. It is unnecessary to make several copies of a row from the
first operand.  Incremental buffers also provide a savings in
processing time due to the reduction in copying time.

The `join_cache_level' system variable controls for which join
operations of which types join buffers are supposed to be used. The
allowable `join_cache_level' values are shown in the following table.

*Option*    *Description*
`0'         No join buffer is used for any join operation.
            This setting can be useful to for assessing
            baseline join performance in comparison to
            performance with non-zero values that enable use
            of join buffering.
`1'         This is the default value. Join buffers are
            employed exactly in the same cases as in versions
            of MySQL prior to 6.0.9: They are used only for
            inner joins that are executed by the original
            Block Nested-Loop (BNL) join algorithm. When this
            algorithm is applied, rows of the inner table are
            accessed through a table scan, a plain index
            scan, or a range index scan.
`2'         The server employs an incremental join buffer for
            a join operation if its first operand is produced
            by a join operation that uses a join buffer
            itself.
`3'         The BNL algorithm is used for an outer join and
            semi-join operation with one inner table, and for
            inner joins.
`4'         The BNL algorithm uses incremental buffers for
            inner tables. In this case, the BNL algorithm can
            be used for nested outer joins and semi-joins
            (outer joins and semi-joins with several inner
            tables). Such an operation can be executed only
            if incremental join buffers are used to join all
            inner tables but the first one.
`5'         The BKA algorithm uses regular buffers for any
            join operation with index access to the joined
            table.
`6'         The BKA algorithm uses incremental buffers for
            any join operation with index access to the
            joined table.
`7'         The BKA algorithm uses regular join buffers with
            a hash table.
`8'         The BKA algorithm uses incremental join buffers
            with a hash table.


File: manual.info,  Node: bnl-optimization,  Next: bka-optimization,  Prev: join-buffer-management,  Up: bnl-bka-optimization

7.2.15.2 Block Nested-Loop Algorithm for Outer Joins and Semi-Joins
...................................................................

As of MySQL 6.0.9, the original implementation of the BNL algorithm has
been extended to support outer join and semi-join operations.

When any of these operations is executed with a join buffer, each row
put into the buffer is supplied with a match flag.

If an outer join operation is executed using a join buffer, each row of
the table produced by the second operand is checked for a match against
each row in the join buffer. When a match is found, a new extended row
is formed (the original row plus columns from the second operand) and
sent for further extensions by the remaining join operations. In
addition, the match flag of the matched row in the buffer is enabled.
After all rows of the table to be joined have been examined, the join
buffer is scanned. Each row from the buffer that does not have its
match flag enabled is extended by `NULL' complements (`NULL' values for
each column in the second operand) and sent for further extensions by
the remaining join operations.

If a join buffer is used for a semi-join operation, only the first
extension by a row from the inner table is sent for further extensions
by the remaining join operations.

If the value of `join_cache_level' is 3, the BNL algorithm is used for
an outer join and semi-join operation with one inner table.

If the value of `join_cache_level' is 4, the BNL algorithm uses
incremental buffers for inner tables. In this case, the BNL algorithm
can be used for nested outer joins and semi-joins (outer joins and
semi-joins with several inner tables). Such an operation can be
executed only if incremental join buffers are used to join all inner
tables but the first one.

In *Note `EXPLAIN': explain. output, use of BNL for a table is
signified when the `Extra' value contains `Using join buffer' and the
`type' value is `ALL', `index', or `range'.


File: manual.info,  Node: bka-optimization,  Prev: bnl-optimization,  Up: bnl-bka-optimization

7.2.15.3 Batched Key Access Joins
.................................

MySQL 6.0.9 introduces a new algorithm to join tables called the
Batched Key Access (BKA) join algorithm. BKA can be applied when there
is an index access to the table produced by the second join operand.
Like the BNL join algorithm, the BKA join algorithm employs a join
buffer to accumulate the interesting columns of the rows produced by
the first operand of the join operation. Then the BKA algorithm builds
keys to access the table to be joined for all rows in the buffer and
submits these keys in a batch to the database engine for index lookups.
Each key in the batch is supplemented with a reference to the row in
the join buffer from which the key originates. This reference is called
the key/range association. The keys are submitted to the engine through
the Multi-Range Read (MRR) interface (see *Note mrr-optimization::).
After submission of the keys, the MMR engine functions perform lookups
in the index in an optimal way, fetching the rows of the joined table
found by these keys, and starts feeding the BKA join algorithm with
matching rows.

For BKA to be used, `join_cache_level' must have a value from 5 to 8
(as described shortly) and the value of the `optimizer_use_mrr' system
variable must not be `'disabled''.

Each matching row is coupled with a reference to a row in the join
buffer. This is exactly the reference passed with the key by which the
matching row has been fetched. so this is the reference to the matched
row in the join buffer. The BKA join algorithm effectively uses this
reference to build the joined rows from the matched and the matching
rows.

There are two scenarios by which MRR functions execute:

   * The first scenario is used for remote storage engines such as
     `NDBCLUSTER'. A package of keys for a portion of rows from the
     join buffer, together with their associations, is sent by MySQL
     Server to NDB nodes. In return, the Server receives a package (or
     several packages) of matching rows coupled with corresponding
     associations. The BKA join algorithm takes these rows and builds
     new joined rows. Then a new portion of keys are sent to NDB nodes
     and the rows from the returned packages are used to build new
     joined rows. The process continues until the last keys from the
     join buffer are sent to NDB nodes and the MySQL server receives and
     joins all rows matching these keys. This improves performance
     because the fewer packages with keys the MySQL Server sends to the
     Cluster, the fewer round trips between the server and the Cluster
     nodes are required to perform the join operation.

   * The second scenario is used for conventional disk-based storage
     engine such as `MyISAM', `InnoDB', `Falcon', and `Maria'. For
     these engines, usually the keys for all rows from the join buffer
     are submitted to the MRR interface at once. Engine-specific MRR
     functions perform index lookups for the submitted keys, get row
     IDs (or primary keys) from them, and then fetch rows for all these
     selected row IDs one by one by request from BKA algorithm. Every
     row is returned with an association reference that enables access
     to the matched row in the join buffer. The row are fetched by the
     MRR functions in an optimal way: They are fetched in the row ID
     (primary key) order. This improves performance because reads are
     in disk order rather than random order.

With the second scenario, a portion of the join buffer is reserved to
store row IDs (primary keys) selected by index lookups and passed as a
parameter to the MMR functions.

There is no special buffer to store keys built for rows from the join
buffer. Instead, a function that builds the key for the next row in the
buffer is passed as a parameter to the MRR functions.

If the value of `join_cache_level' is 5 or 6, the BKA algorithm is used
for any join operation with index access to the joined table. Level 5
uses regular join buffers.  Level 6 uses incremental join buffers.

The BKA algorithm supports outer join as well as semi-join operations.
For outer joins and semi-joins with one inner table, both regular and
incremental join buffers can be used.  For nested outer joins and
semi-joins, only incremental join buffers can be used.

Currently, the `Falcon' storage engine cannot use associations passed
to it together with keys. `Falcon' builds a bitmap of rows for keys and
uses this bitmap to access matching rows, so it returns a matching row
without a reference to the matched row. To quickly find all matched
rows in the join buffer, a hash table of the keys passed to the MRR
interface is built at the very end of the join buffer.

Any row in the join buffer with key K is linked to a list of rows with
the same key. The list is attached to the key that is stored in the
hash table.

If the average frequency of keys in the join buffer is 2 or greater, it
makes sense to use a join buffer with a hash table with the `MyISAM' or
`InnoDB' storage engine as well. In this case, fewer keys are passed
for lookups.

To use a join buffer with hash table, set the value of
`join_cache_level' to 7 or 8.  Level 7 is used for regular join buffers
with all interesting columns. Level 8 is used for incremental join
buffers.

In *Note `EXPLAIN': explain. output, use of BKA for a table is
signified when the `Extra' value contains `Using join buffer' and the
`type' value is `ref' or `eq_ref'.


File: manual.info,  Node: order-by-optimization,  Next: group-by-optimization,  Prev: bnl-bka-optimization,  Up: query-speed

7.2.16 `ORDER BY' Optimization
------------------------------

In some cases, MySQL can use an index to satisfy an `ORDER BY' clause
without doing any extra sorting.

The index can also be used even if the `ORDER BY' does not match the
index exactly, as long as all of the unused portions of the index and
all the extra `ORDER BY' columns are constants in the `WHERE' clause.
The following queries use the index to resolve the `ORDER BY' part:

     SELECT * FROM t1
       ORDER BY KEY_PART1,KEY_PART2,... ;

     SELECT * FROM t1
       WHERE KEY_PART1=CONSTANT
       ORDER BY KEY_PART2;

     SELECT * FROM t1
       ORDER BY KEY_PART1 DESC, KEY_PART2 DESC;

     SELECT * FROM t1
       WHERE KEY_PART1=1
       ORDER BY KEY_PART1 DESC, KEY_PART2 DESC;

In some cases, MySQL _cannot_ use indexes to resolve the `ORDER BY',
although it still uses indexes to find the rows that match the `WHERE'
clause. These cases include the following:

   * You use `ORDER BY' on different keys:

          SELECT * FROM t1 ORDER BY KEY1, KEY2;

   * You use `ORDER BY' on non-consecutive parts of a key:

          SELECT * FROM t1 WHERE KEY2=CONSTANT ORDER BY KEY_PART2;

   * You mix `ASC' and `DESC':

          SELECT * FROM t1 ORDER BY KEY_PART1 DESC, KEY_PART2 ASC;

   * The key used to fetch the rows is not the same as the one used in
     the `ORDER BY':

          SELECT * FROM t1 WHERE KEY2=CONSTANT ORDER BY KEY1;

   * You use `ORDER BY' with an expression that includes terms other
     than the key column name:

          SELECT * FROM t1 ORDER BY ABS(KEY);
          SELECT * FROM t1 ORDER BY -KEY;

   * You are joining many tables, and the columns in the `ORDER BY' are
     not all from the first non-constant table that is used to retrieve
     rows. (This is the first table in the *Note `EXPLAIN': explain.
     output that does not have a `const' join type.)

   * You have different `ORDER BY' and `GROUP BY' expressions.

   * You index only a prefix of a column named in the `ORDER BY'
     clause. In this case, the index cannot be used to fully resolve
     the sort order. For example, if you have a *Note `CHAR(20)': char.
     column, but index only the first 10 bytes, the index cannot
     distinguish values past the 10th byte and a `filesort' will be
     needed.

   * The type of table index used does not store rows in order.  For
     example, this is true for a `HASH' index in a `MEMORY' table.

Availability of an index for sorting may be affected by the use of
column aliases. Suppose that the column `t1.a' is indexed. In this
statement, the name of the column in the select list is `a'. It refers
to `t1.a', so for the reference to `a' in the `ORDER BY', the index can
be used:

     SELECT a FROM t1 ORDER BY a;

In this statement, the name of the column in the select list is also
`a', but it is the alias name. It refers to `ABS(a)', so for the
reference to `a' in the `ORDER BY', the index cannot be used:

     SELECT ABS(a) AS a FROM t1 ORDER BY a;

In the following statement, the `ORDER BY' refers to a name that is not
the name of a column in the select list. But there is a column in `t1'
named `a', so the `ORDER BY' uses that, and the index can be used. (The
resulting sort order may be completely different from the order for
`ABS(a)', of course.)

     SELECT ABS(a) AS b FROM t1 ORDER BY a;

By default, MySQL sorts all `GROUP BY COL1, COL2, ...' queries as if you
specified `ORDER BY COL1, COL2, ...' in the query as well. If you
include an `ORDER BY' clause explicitly that contains the same column
list, MySQL optimizes it away without any speed penalty, although the
sorting still occurs. If a query includes `GROUP BY' but you want to
avoid the overhead of sorting the result, you can suppress sorting by
specifying `ORDER BY NULL'.  For example:

     INSERT INTO foo
     SELECT a, COUNT(*) FROM bar GROUP BY a ORDER BY NULL;

With `EXPLAIN SELECT ... ORDER BY', you can check whether MySQL can use
indexes to resolve the query. It cannot if you see `Using filesort' in
the `Extra' column. See *Note using-explain::.

MySQL has two `filesort' algorithms for sorting and retrieving results.
The original method uses only the `ORDER BY' columns. The modified
method uses not just the `ORDER BY' columns, but all the columns used
in the query.

The optimizer selects which `filesort' algorithm to use. It normally
uses the modified algorithm except when *Note `BLOB': blob. or *Note
`TEXT': blob. columns are involved, in which case it uses the original
algorithm.

The original `filesort' algorithm works as follows:

  1. Read all rows according to key or by table scanning. Rows that do
     not match the `WHERE' clause are skipped.

  2. For each row, store a pair of values in a buffer (the sort key and
     the row pointer). The size of the buffer is the value of the
     `sort_buffer_size' system variable.

  3. When the buffer gets full, run a qsort (quicksort) on it and store
     the result in a temporary file. Save a pointer to the sorted
     block. (If all pairs fit into the sort buffer, no temporary file
     is created.)

  4. Repeat the preceding steps until all rows have been read.

  5. Do a multi-merge of up to `MERGEBUFF' (7) regions to one block in
     another temporary file. Repeat until all blocks from the first
     file are in the second file.

  6. Repeat the following until there are fewer than `MERGEBUFF2' (15)
     blocks left.

  7. On the last multi-merge, only the pointer to the row (the last
     part of the sort key) is written to a result file.

  8. Read the rows in sorted order by using the row pointers in the
     result file. To optimize this, we read in a big block of row
     pointers, sort them, and use them to read the rows in sorted order
     into a row buffer. The size of the buffer is the value of the
     `read_rnd_buffer_size' system variable. The code for this step is
     in the `sql/records.cc' source file.

One problem with this approach is that it reads rows twice: One time
when evaluating the `WHERE' clause, and again after sorting the pair
values. And even if the rows were accessed successively the first time
(for example, if a table scan is done), the second time they are
accessed randomly. (The sort keys are ordered, but the row positions
are not.)

The modified `filesort' algorithm incorporates an optimization such
that it records not only the sort key value and row position, but also
the columns required for the query.  This avoids reading the rows
twice. The modified `filesort' algorithm works like this:

  1. Read the rows that match the `WHERE' clause.

  2. For each row, record a tuple of values consisting of the sort key
     value and row position, and also the columns required for the
     query.

  3. Sort the tuples by sort key value

  4. Retrieve the rows in sorted order, but read the required columns
     directly from the sorted tuples rather than by accessing the table
     a second time.

Using the modified `filesort' algorithm, the tuples are longer than the
pairs used in the original method, and fewer of them fit in the sort
buffer (the size of which is given by `sort_buffer_size'). As a result,
it is possible for the extra I/O to make the modified approach slower,
not faster. To avoid a slowdown, the optimization is used only if the
total size of the extra columns in the sort tuple does not exceed the
value of the `max_length_for_sort_data' system variable. (A symptom of
setting the value of this variable too high is that you should see high
disk activity and low CPU activity.)

For slow queries for which `filesort' is not used, you might try
lowering `max_length_for_sort_data' to a value that is appropriate to
trigger a `filesort'.

If you want to increase `ORDER BY' speed, check whether you can get
MySQL to use indexes rather than an extra sorting phase. If this is not
possible, you can try the following strategies:

   * Increase the size of the `sort_buffer_size' variable.

   * Increase the size of the `read_rnd_buffer_size' variable.

   * Use less RAM per row by declaring columns only as large as they
     need to be to hold the values stored in them. For example,
     `CHAR(16)' is better than `CHAR(200)' if values never exceed 16
     characters.

   * Change `tmpdir' to point to a dedicated file system with large
     amounts of free space. Also, this option accepts several paths
     that are used in round-robin fashion, so you can use this feature
     to spread the load across several directories. Paths should be
     separated by colon characters (``:'') on Unix and semicolon
     characters (``;'') on Windows, NetWare, and OS/2. The paths should
     be for directories in file systems that are located on different
     _physical_ disks, not different partitions on the same disk.


File: manual.info,  Node: group-by-optimization,  Next: distinct-optimization,  Prev: order-by-optimization,  Up: query-speed

7.2.17 `GROUP BY' Optimization
------------------------------

* Menu:

* loose-index-scan::             Loose index scan
* tight-index-scan::             Tight index scan

The most general way to satisfy a `GROUP BY' clause is to scan the
whole table and create a new temporary table where all rows from each
group are consecutive, and then use this temporary table to discover
groups and apply aggregate functions (if any). In some cases, MySQL is
able to do much better than that and to avoid creation of temporary
tables by using index access.

The most important preconditions for using indexes for `GROUP BY' are
that all `GROUP BY' columns reference attributes from the same index,
and that the index stores its keys in order (for example, this is a
`BTREE' index and not a `HASH' index). Whether use of temporary tables
can be replaced by index access also depends on which parts of an index
are used in a query, the conditions specified for these parts, and the
selected aggregate functions.

In MySQL, `GROUP BY' is used for sorting, so the server may also apply
`ORDER BY' optimizations to grouping. See *Note order-by-optimization::.

There are two ways to execute a `GROUP BY' query via index access, as
detailed in the following sections.  In the first method, the grouping
operation is applied together with all range predicates (if any). The
second method first performs a range scan, and then groups the
resulting tuples.


File: manual.info,  Node: loose-index-scan,  Next: tight-index-scan,  Prev: group-by-optimization,  Up: group-by-optimization

7.2.17.1 Loose index scan
.........................

The most efficient way to process `GROUP BY' is when the index is used
to directly retrieve the group columns. With this access method, MySQL
uses the property of some index types that the keys are ordered (for
example, `BTREE'). This property enables use of lookup groups in an
index without having to consider all keys in the index that satisfy all
`WHERE' conditions.  This access method considers only a fraction of
the keys in an index, so it is called a _loose index scan_. When there
is no `WHERE' clause, a loose index scan reads as many keys as the
number of groups, which may be a much smaller number than that of all
keys. If the `WHERE' clause contains range predicates (see the
discussion of the `range' join type in *Note using-explain::), a loose
index scan looks up the first key of each group that satisfies the range
conditions, and again reads the least possible number of keys.  This is
possible under the following conditions:

   * The query is over a single table.

   * The `GROUP BY' includes the first consecutive parts of the index.
     (If, instead of `GROUP BY', the query has a `DISTINCT' clause, all
     distinct attributes refer to the beginning of the index.)

   * The only aggregate functions used (if any) are `MIN()' and
     `MAX()', and all of them refer to the same column.

   * Any other parts of the index than those from the `GROUP BY'
     referenced in the query must be constants (that is, they must be
     referenced in equalities with constants), except for the argument
     of `MIN()' or `MAX()' functions.

The *Note `EXPLAIN': explain. output for such queries shows `Using
index for group-by' in the `Extra' column.

The following queries fall into this category, assuming that there is
an index `idx(c1,c2,c3)' on table `t1(c1,c2,c3,c4)':

     SELECT c1, c2 FROM t1 GROUP BY c1, c2;
     SELECT DISTINCT c1, c2 FROM t1;
     SELECT c1, MIN(c2) FROM t1 GROUP BY c1;
     SELECT c1, c2 FROM t1 WHERE c1 < CONST GROUP BY c1, c2;
     SELECT MAX(c3), MIN(c3), c1, c2 FROM t1 WHERE c2 > CONST GROUP BY c1, c2;
     SELECT c2 FROM t1 WHERE c1 < CONST GROUP BY c1, c2;
     SELECT c1, c2 FROM t1 WHERE c3 = CONST GROUP BY c1, c2;

The following queries cannot be executed with this quick select method,
for the reasons given:

   * There are aggregate functions other than `MIN()' or `MAX()', for
     example:

          SELECT c1, SUM(c2) FROM t1 GROUP BY c1;

   * The columns in the `GROUP BY' clause do not refer to the beginning
     of the index, as shown here:

          SELECT c1,c2 FROM t1 GROUP BY c2, c3;

   * The query refers to a part of a key that comes after the `GROUP
     BY' part, and for which there is no equality with a constant, an
     example being:

          SELECT c1,c3 FROM t1 GROUP BY c1, c2;


File: manual.info,  Node: tight-index-scan,  Prev: loose-index-scan,  Up: group-by-optimization

7.2.17.2 Tight index scan
.........................

A tight index scan may be either a full index scan or a range index
scan, depending on the query conditions.

When the conditions for a loose index scan are not met, it is still
possible to avoid creation of temporary tables for `GROUP BY' queries.
If there are range conditions in the `WHERE' clause, this method reads
only the keys that satisfy these conditions. Otherwise, it performs an
index scan. Because this method reads all keys in each range defined by
the `WHERE' clause, or scans the whole index if there are no range
conditions, we term it a _tight index scan_. Notice that with a tight
index scan, the grouping operation is performed only after all keys
that satisfy the range conditions have been found.

For this method to work, it is sufficient that there is a constant
equality condition for all columns in a query referring to parts of the
key coming before or in between parts of the `GROUP BY' key. The
constants from the equality conditions fill in any `gaps' in the search
keys so that it is possible to form complete prefixes of the index.
These index prefixes then can be used for index lookups. If we require
sorting of the `GROUP BY' result, and it is possible to form search keys
that are prefixes of the index, MySQL also avoids extra sorting
operations because searching with prefixes in an ordered index already
retrieves all the keys in order.

The following queries do not work with the loose index scan access
method described earlier, but still work with the tight index scan
access method (assuming that there is an index `idx(c1,c2,c3)' on table
`t1(c1,c2,c3,c4)').

   * There is a gap in the `GROUP BY', but it is covered by the
     condition `c2 = 'a'':

          SELECT c1, c2, c3 FROM t1 WHERE c2 = 'a' GROUP BY c1, c3;

   * The `GROUP BY' does not begin with the first part of the key, but
     there is a condition that provides a constant for that part:

          SELECT c1, c2, c3 FROM t1 WHERE c1 = 'a' GROUP BY c2, c3;


File: manual.info,  Node: distinct-optimization,  Next: in-subquery-optimization,  Prev: group-by-optimization,  Up: query-speed

7.2.18 `DISTINCT' Optimization
------------------------------

`DISTINCT' combined with `ORDER BY' needs a temporary table in many
cases.

Because `DISTINCT' may use `GROUP BY', you should be aware of how MySQL
works with columns in `ORDER BY' or `HAVING' clauses that are not part
of the selected columns. See *Note group-by-hidden-columns::.

In most cases, a `DISTINCT' clause can be considered as a special case
of `GROUP BY'. For example, the following two queries are equivalent:

     SELECT DISTINCT c1, c2, c3 FROM t1
     WHERE c1 > CONST;

     SELECT c1, c2, c3 FROM t1
     WHERE c1 > CONST GROUP BY c1, c2, c3;

Due to this equivalence, the optimizations applicable to `GROUP BY'
queries can be also applied to queries with a `DISTINCT' clause. Thus,
for more details on the optimization possibilities for `DISTINCT'
queries, see *Note group-by-optimization::.

When combining `LIMIT ROW_COUNT' with `DISTINCT', MySQL stops as soon
as it finds ROW_COUNT unique rows.

If you do not use columns from all tables named in a query, MySQL stops
scanning any unused tables as soon as it finds the first match. In the
following case, assuming that `t1' is used before `t2' (which you can
check with *Note `EXPLAIN': explain.), MySQL stops reading from `t2'
(for any particular row in `t1') when it finds the first row in `t2':

     SELECT DISTINCT t1.a FROM t1, t2 where t1.a=t2.a;


File: manual.info,  Node: in-subquery-optimization,  Next: limit-optimization,  Prev: distinct-optimization,  Up: query-speed

7.2.19 Optimizing `IN'/`=ANY' Subqueries
----------------------------------------

Certain optimizations are applicable to comparisons that use the `IN'
operator to test subquery results (or that use `=ANY', which is
equivalent). This section discusses these optimizations, particularly
with regard to the challenges that `NULL' values present.  Suggestions
on what you can do to help the optimizer are given at the end of the
discussion.

Consider the following subquery comparison:

     OUTER_EXPR IN (SELECT INNER_EXPR FROM ... WHERE SUBQUERY_WHERE)

MySQL evaluates queries `from outside to inside.' That is, it first
obtains the value of the outer expression OUTER_EXPR, and then runs the
subquery and captures the rows that it produces.

A very useful optimization is to `inform' the subquery that the only
rows of interest are those where the inner expression INNER_EXPR is
equal to OUTER_EXPR. This is done by pushing down an appropriate
equality into the subquery's `WHERE' clause. That is, the comparison is
converted to this:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE AND OUTER_EXPR=INNER_EXPR)

After the conversion, MySQL can use the pushed-down equality to limit
the number of rows that it must examine when evaluating the subquery.

More generally, a comparison of N values to a subquery that returns
N-value rows is subject to the same conversion. If OE_I and IE_I
represent corresponding outer and inner expression values, this
subquery comparison:

     (OE_1, ..., OE_N) IN
       (SELECT IE_1, ..., IE_N FROM ... WHERE SUBQUERY_WHERE)

Becomes:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE
                               AND OE_1 = IE_1
                               AND ...
                               AND OE_N = IE_N)

The following discussion assumes a single pair of outer and inner
expression values for simplicity.

The conversion just described has its limitations. It is valid only if
we ignore possible `NULL' values. That is, the `pushdown' strategy
works as long as both of these two conditions are true:

   * OUTER_EXPR and INNER_EXPR cannot be `NULL'.

   * You do not need to distinguish `NULL' from `FALSE' subquery
     results. (If the subquery is a part of an `OR' or `AND' expression
     in the `WHERE' clause, MySQL assumes that you don't care.)

When either or both of those conditions do not hold, optimization is
more complex.

Suppose that OUTER_EXPR is known to be a non-`NULL' value but the
subquery does not produce a row such that OUTER_EXPR = INNER_EXPR. Then
`OUTER_EXPR IN (SELECT ...)' evaluates as follows:

   * `NULL', if the *Note `SELECT': select. produces any row where
     INNER_EXPR is `NULL'

   * `FALSE', if the *Note `SELECT': select. produces only non-`NULL'
     values or produces nothing

In this situation, the approach of looking for rows with `OUTER_EXPR =
INNER_EXPR' is no longer valid. It is necessary to look for such rows,
but if none are found, also look for rows where INNER_EXPR is `NULL'.
Roughly speaking, the subquery can be converted to:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE AND
             (OUTER_EXPR=INNER_EXPR OR INNER_EXPR IS NULL))

The need to evaluate the extra `IS NULL' condition is why MySQL has the
`ref_or_null' access method:

     mysql> EXPLAIN
         -> SELECT OUTER_EXPR IN (SELECT t2.maybe_null_key
         ->                       FROM t2, t3 WHERE ...)
         -> FROM t1;
     *************************** 1. row ***************************
                id: 1
       select_type: PRIMARY
             table: t1
     ...
     *************************** 2. row ***************************
                id: 2
       select_type: DEPENDENT SUBQUERY
             table: t2
              type: ref_or_null
     possible_keys: maybe_null_key
               key: maybe_null_key
           key_len: 5
               ref: func
              rows: 2
             Extra: Using where; Using index
     ...

The `unique_subquery' and `index_subquery' subqery-specific access
methods also have or-null variants.  However, they are not visible in
*Note `EXPLAIN': explain. output, so you must use `EXPLAIN EXTENDED'
followed by *Note `SHOW WARNINGS': show-warnings. (note the `checking
NULL' in the warning message):

     mysql> EXPLAIN EXTENDED
         -> SELECT OUTER_EXPR IN (SELECT maybe_null_key FROM t2) FROM t1\G
     *************************** 1. row ***************************
                id: 1
       select_type: PRIMARY
             table: t1
     ...
     *************************** 2. row ***************************
                id: 2
       select_type: DEPENDENT SUBQUERY
             table: t2
              type: index_subquery
     possible_keys: maybe_null_key
               key: maybe_null_key
           key_len: 5
               ref: func
              rows: 2
             Extra: Using index

     mysql> SHOW WARNINGS\G
     *************************** 1. row ***************************
       Level: Note
        Code: 1003
     Message: select (`test`.`t1`.`outer_expr`,
              (((`test`.`t1`.`outer_expr`) in t2 on
              maybe_null_key checking NULL))) AS `outer_expr IN (SELECT
              maybe_null_key FROM t2)` from `test`.`t1`

The additional `OR ... IS NULL' condition makes query execution
slightly more complicated (and some optimizations within the subquery
become inapplicable), but generally this is tolerable.

The situation is much worse when OUTER_EXPR can be `NULL'. According to
the SQL interpretation of `NULL' as `unknown value,' `NULL IN (SELECT
INNER_EXPR ...)' should evaluate to:

   * `NULL', if the *Note `SELECT': select. produces any rows

   * `FALSE', if the *Note `SELECT': select. produces no rows

For proper evaluation, it is necessary to be able to check whether the
*Note `SELECT': select. has produced any rows at all, so `OUTER_EXPR =
INNER_EXPR' cannot be pushed down into the subquery. This is a problem,
because many real world subqueries become very slow unless the equality
can be pushed down.

Essentially, there must be different ways to execute the subquery
depending on the value of OUTER_EXPR.

The optimizer chooses SQL compliance over speed, so it accounts for the
possibility that OUTER_EXPR might be `NULL'.

If OUTER_EXPR is `NULL', to evaluate the following expression, it is
necessary to run the *Note `SELECT': select.  to determine whether it
produces any rows:

     NULL IN (SELECT INNER_EXPR FROM ... WHERE SUBQUERY_WHERE)

It is necessary to run the original *Note `SELECT': select. here,
without any pushed-down equalities of the kind mentioned earlier.

On the other hand, when OUTER_EXPR is not `NULL', it is absolutely
essential that this comparison:

     OUTER_EXPR IN (SELECT INNER_EXPR FROM ... WHERE SUBQUERY_WHERE)

be converted to this expression that uses a pushed-down condition:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE AND OUTER_EXPR=INNER_EXPR)

Without this conversion, subqueries will be slow. To solve the dilemma
of whether to push down or not push down conditions into the subquery,
the conditions are wrapped in `trigger' functions. Thus, an expression
of the following form:

     OUTER_EXPR IN (SELECT INNER_EXPR FROM ... WHERE SUBQUERY_WHERE)

is converted into:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE
                               AND trigcond(OUTER_EXPR=INNER_EXPR))

More generally, if the subquery comparison is based on several pairs of
outer and inner expressions, the conversion takes this comparison:

     (OE_1, ..., OE_N) IN (SELECT IE_1, ..., IE_N FROM ... WHERE SUBQUERY_WHERE)

and converts it to this expression:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE
                               AND trigcond(OE_1=IE_1)
                               AND ...
                               AND trigcond(OE_N=IE_N)
            )

Each `trigcond(X)' is a special function that evaluates to the
following values:

   * X when the `linked' outer expression OE_I is not `NULL'

   * `TRUE' when the `linked' outer expression OE_I is `NULL'

Note that trigger functions are _not_ triggers of the kind that you
create with *Note `CREATE TRIGGER': create-trigger.

Equalities that are wrapped into `trigcond()' functions are not first
class predicates for the query optimizer. Most optimizations cannot
deal with predicates that may be turned on and off at query execution
time, so they assume any `trigcond(X)' to be an unknown function and
ignore it. At the moment, triggered equalities can be used by those
optimizations:

   * Reference optimizations: `trigcond(X=Y [OR Y IS NULL])' can be
     used to construct `ref', `eq_ref', or `ref_or_null' table accesses.

   * Index lookup-based subquery execution engines: `trigcond(X=Y)' can
     be used to construct `unique_subquery' or `index_subquery'
     accesses.

   * Table-condition generator: If the subquery is a join of several
     tables, the triggered condition will be checked as soon as
     possible.

When the optimizer uses a triggered condition to create some kind of
index lookup-based access (as for the first two items of the preceding
list), it must have a fallback strategy for the case when the condition
is turned off. This fallback strategy is always the same: Do a full
table scan. In *Note `EXPLAIN': explain. output, the fallback shows up
as `Full scan on NULL key' in the `Extra' column:

     mysql> EXPLAIN SELECT t1.col1,
         -> t1.col1 IN (SELECT t2.key1 FROM t2 WHERE t2.col2=t1.col2) FROM t1\G
     *************************** 1. row ***************************
                id: 1
       select_type: PRIMARY
             table: t1
             ...
     *************************** 2. row ***************************
                id: 2
       select_type: DEPENDENT SUBQUERY
             table: t2
              type: index_subquery
     possible_keys: key1
               key: key1
           key_len: 5
               ref: func
              rows: 2
             Extra: Using where; Full scan on NULL key

If you run `EXPLAIN EXTENDED' followed by *Note `SHOW WARNINGS':
show-warnings, you can see the triggered condition:

     *************************** 1. row ***************************
       Level: Note
        Code: 1003
     Message: select `test`.`t1`.`col1` AS `col1`,
              <in_optimizer>(`test`.`t1`.`col1`,
              <exists>(<index_lookup>(<cache>(`test`.`t1`.`col1`) in t2
              on key1 checking NULL
              where (`test`.`t2`.`col2` = `test`.`t1`.`col2`) having
              trigcond(<is_not_null_test>(`test`.`t2`.`key1`))))) AS
              `t1.col1 IN (select t2.key1 from t2 where t2.col2=t1.col2)`
              from `test`.`t1`

The use of triggered conditions has some performance implications. A
`NULL IN (SELECT ...)' expression now may cause a full table scan
(which is slow) when it previously did not. This is the price paid for
correct results (the goal of the trigger-condition strategy was to
improve compliance and not speed).

For multiple-table subqueries, execution of `NULL IN (SELECT ...)' will
be particularly slow because the join optimizer doesn't optimize for
the case where the outer expression is `NULL'. It assumes that subquery
evaluations with `NULL' on the left side are very rare, even if there
are statistics that indicate otherwise.  On the other hand, if the
outer expression might be `NULL' but never actually is, there is no
performance penalty.

To help the query optimizer better execute your queries, use these tips:

   * A column must be declared as `NOT NULL' if it really is. (This
     also helps other aspects of the optimizer.)

   * If you don't need to distinguish a `NULL' from `FALSE' subquery
     result, you can easily avoid the slow execution path. Replace a
     comparison that looks like this:

          OUTER_EXPR IN (SELECT INNER_EXPR FROM ...)

     with this expression:

          (OUTER_EXPR IS NOT NULL) AND (OUTER_EXPR IN (SELECT INNER_EXPR FROM ...))

     Then `NULL IN (SELECT ...)' will never be evaluated because MySQL
     stops evaluating `AND' parts as soon as the expression result is
     clear.


File: manual.info,  Node: limit-optimization,  Next: switchable-optimizations,  Prev: in-subquery-optimization,  Up: query-speed

7.2.20 `LIMIT' Optimization
---------------------------

In some cases, MySQL handles a query differently when you are using
`LIMIT ROW_COUNT' and not using `HAVING':

   * If you are selecting only a few rows with `LIMIT', MySQL uses
     indexes in some cases when normally it would prefer to do a full
     table scan.

   * If you use `LIMIT ROW_COUNT' with `ORDER BY', MySQL ends the
     sorting as soon as it has found the first ROW_COUNT rows of the
     sorted result, rather than sorting the entire result. If ordering
     is done by using an index, this is very fast. If a filesort must
     be done, all rows that match the query without the `LIMIT' clause
     must be selected, and most or all of them must be sorted, before
     it can be ascertained that the first ROW_COUNT rows have been
     found. In either case, after the initial rows have been found,
     there is no need to sort any remainder of the result set, and
     MySQL does not do so.

   * When combining `LIMIT ROW_COUNT' with `DISTINCT', MySQL stops as
     soon as it finds ROW_COUNT unique rows.

   * In some cases, a `GROUP BY' can be resolved by reading the key in
     order (or doing a sort on the key) and then calculating summaries
     until the key value changes. In this case, `LIMIT ROW_COUNT' does
     not calculate any unnecessary `GROUP BY' values.

   * As soon as MySQL has sent the required number of rows to the
     client, it aborts the query unless you are using
     `SQL_CALC_FOUND_ROWS'.

   * `LIMIT 0' quickly returns an empty set.  This can be useful for
     checking the validity of a query.  When using one of the MySQL
     APIs, it can also be employed for obtaining the types of the
     result columns. (This trick does not work in the MySQL Monitor (the
     *Note `mysql': mysql. program), which merely displays `Empty set'
     in such cases; you should instead use *Note `SHOW COLUMNS':
     show-columns. or *Note `DESCRIBE': describe. for this purpose.)

   * When the server uses temporary tables to resolve the query, it
     uses the `LIMIT ROW_COUNT' clause to calculate how much space is
     required.


File: manual.info,  Node: switchable-optimizations,  Next: how-to-avoid-table-scan,  Prev: limit-optimization,  Up: query-speed

7.2.21 Using `optimizer_switch' to Control Optimizations
--------------------------------------------------------

The `optimizer_switch' system variable enables control over individual
optimizations.

As of MySQL 6.0.11, the value of the `optimizer_switch' system variable
is a set of flags, each of which has a value of `on' or `off' to
indicate whether the corresponding optimization is enabled or disabled.
This variable has global and session values and be changed at runtime.
The global default can be set at server startup.

To see the current set of optimizer values, select the variable value:

     mysql> SELECT @@optimizer_switch\G
     *************************** 1. row ***************************
     @@optimizer_switch: firstmatch=on,index_merge=on,
                         index_merge_union=on,
                         index_merge_sort_union=on,
                         index_merge_intersection=on,
                         loosescan=on,materialization=on,
                         semijoin=on

To change the value of `optimizer_switch', assign a value consisting of
a comma-separated list of one or more commands:

     SET [GLOBAL|SESSION] optimizer_switch='COMMAND[,COMMAND]...';

Each COMMAND value should have one of the forms shown in the following
table.

*Command Syntax*   *Meaning*
`default'          Reset every optimization to its default value
`OPT_NAME=default' Set the named optimization to its default value
`OPT_NAME=off'     Disable the named optimization
`OPT_NAME=on'      Enable the named optimization

The order of the commands in the value does not matter, although
`default' is executed first if present.  Specifying any given OPT_NAME
more than once in the value is not allowed and causes an error. Any
errors in the value cause the entire statement to fail with an error
and the current value of `optimizer_switch' remains unchanged.

The following table lists the allowable OPT_NAME optimization names.

*Optimization Name*       *Meaning*
`index_merge'             Controls all Index Merge optimizations
`index_merge_union'       Controls the Index Merge Union Access
                          optimization
`index_merge_sort_union'  Controls the Index Merge Sort-Union Access
                          optimization
`index_merge_intersection'Controls the Index Merge Intersection Access
                          optimization
`semijoin'                Controls all semi-join optimizations
`materialization'         Controls materialization (including semi-join
                          materialization)
`loosescan'               Controls the semi-join LooseScan strategy (not
                          to be confused with LooseScan for `GROUP BY')
`firstmatch'              Controls the semi-join FirstMatch strategy

For information about Index Merge, see *Note index-merge-optimization::.

When you assign a value to `optimizer_switch', optimizations that are
not mentioned keep their current values. This makes it possible to
enable or disable specific optimizations in a single statement without
affecting other optimizations. The statement does not depend on what
other optimizer flags exist and what their values are. Suppose that all
Index Merge optimizations are enabled:

     mysql> SELECT @@optimizer_switch\G
     *************************** 1. row ***************************
     @@optimizer_switch: firstmatch=on,index_merge=on,
                         index_merge_union=on,
                         index_merge_sort_union=on,
                         index_merge_intersection=on,
                         loosescan=on,materialization=on,
                         semijoin=on
     1 row in set (0.00 sec)

If the server is using the Index Merge Union or Index Merge Sort-Union
access methods for certain queries and you want to check whether the
optimizer will perform better without them, set the variable value like
this:

     mysql> SET optimizer_switch='index_merge_union=off,index_merge_sort_union=off';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @@optimizer_switch\G
     *************************** 1. row ***************************
     @@optimizer_switch: firstmatch=on,index_merge=on,
                         index_merge_union=off,
                         index_merge_sort_union=off,
                         index_merge_intersection=on,
                         loosescan=on,materialization=on,
                         semijoin=on
     1 row in set (0.00 sec)


File: manual.info,  Node: how-to-avoid-table-scan,  Next: information-schema-optimization,  Prev: switchable-optimizations,  Up: query-speed

7.2.22 How to Avoid Table Scans
-------------------------------

The output from *Note `EXPLAIN': explain. shows `ALL' in the `type'
column when MySQL uses a table scan to resolve a query. This usually
happens under the following conditions:

   * The table is so small that it is faster to perform a table scan
     than to bother with a key lookup. This is common for tables with
     fewer than 10 rows and a short row length.

   * There are no usable restrictions in the `ON' or `WHERE' clause for
     indexed columns.

   * You are comparing indexed columns with constant values and MySQL
     has calculated (based on the index tree) that the constants cover
     too large a part of the table and that a table scan would be
     faster. See *Note where-optimizations::.

   * You are using a key with low cardinality (many rows match the key
     value) through another column. In this case, MySQL assumes that by
     using the key it probably will do many key lookups and that a
     table scan would be faster.

MySQL Enterprise

For expert advice on avoiding excessive table scans subscribe to the
MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

For small tables, a table scan often is appropriate and the performance
impact is negligible. For large tables, try the following techniques to
avoid having the optimizer incorrectly choose a table scan:

   * Use `ANALYZE TABLE TBL_NAME' to update the key distributions for
     the scanned table. See *Note analyze-table::.

   * Use `FORCE INDEX' for the scanned table to tell MySQL that table
     scans are very expensive compared to using the given index:

          SELECT * FROM t1, t2 FORCE INDEX (INDEX_FOR_COLUMN)
            WHERE t1.COL_NAME=t2.COL_NAME;

     See *Note index-hints::.

   * Start *Note `mysqld': mysqld. with the `--max-seeks-for-key=1000'
     option or use `SET max_seeks_for_key=1000' to tell the optimizer
     to assume that no key scan causes more than 1,000 key seeks. See
     *Note server-system-variables::.


File: manual.info,  Node: information-schema-optimization,  Next: insert-speed,  Prev: how-to-avoid-table-scan,  Up: query-speed

7.2.23 `INFORMATION_SCHEMA' Optimization
----------------------------------------

In MySQL 6.0.4, changes to the implementation of `INFORMATION_SCHEMA'
were made that optimize certain types of queries for
`INFORMATION_SCHEMA' tables so that they execute more quickly. This
section provides guidelines on writing queries that take advantage of
these optimizations. In general, the strategies outlined here minimize
the need for the server to access the file system to obtain the
information that makes up the contents of `INFORMATION_SCHEMA' tables.
By writing queries that enable the server to avoid directory scans or
opening table files, you will obtain better performance.

*1) Try to use constant lookup values for database and table names in
the `WHERE' clause*

You can take advantage of this principle as follows:

   * To look up databases or tables, use expressions that evaluate to a
     constant, such as literal values, functions that return a
     constant, or scalar subqueries.

   * Avoid queries that use a non-constant database name lookup value
     (or no lookup value) because they require a scan of the data
     directory to find matching database directory names.

   * Within a database, avoid queries that use a non-constant table
     name lookup value (or no lookup value) because they require a scan
     of the database directory to find matching table files.

This principle applies to the `INFORMATION_SCHEMA' tables shown in the
following table, which shows the columns for which a constant lookup
value enables the server to avoid a directory scan. For example, if you
are selecting from *Note `TABLES': tables-table, using a constant lookup
value for `TABLE_SCHEMA' in the `WHERE' clause enables a data directory
scan to be avoided.

*Table*                  *Column to specify to    *Column to specify to
                         avoid data directory     avoid database directory
                         scan*                    scan*
*Note `COLUMNS':         `TABLE_SCHEMA'           `TABLE_NAME'
columns-table.                                    
*Note                    `TABLE_SCHEMA'           `TABLE_NAME'
`KEY_COLUMN_USAGE':                               
key-column-usage-table.                           
*Note `PARTITIONS':      `TABLE_SCHEMA'           `TABLE_NAME'
partitions-table.                                 
*Note                    `CONSTRAINT_SCHEMA'      `TABLE_NAME'
`REFERENTIAL_CONSTRAINTS':                         
referential-constraints-table.                         
*Note `STATISTICS':      `TABLE_SCHEMA'           `TABLE_NAME'
statistics-table.                                 
*Note `TABLES':          `TABLE_SCHEMA'           `TABLE_NAME'
tables-table.                                     
*Note                    `TABLE_SCHEMA'           `TABLE_NAME'
`TABLE_CONSTRAINTS':                              
table-constraints-table.                          
*Note `TRIGGERS':        `EVENT_OBJECT_SCHEMA'    `EVENT_OBJECT_TABLE'
triggers-table.                                   
*Note `VIEWS':           `TABLE_SCHEMA'           `TABLE_NAME'
views-table.                                      

The benefit of a query that is limited to a specific constant database
name is that checks need be made only for the named database directory.
Example:

     SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA = 'test';

Use of the literal database name `test' enables the server to check
only the `test' database directory, regardless of how many databases
there might be. By contrast, the following query is less efficient
because it requires a scan of the data directory to determine which
database names match the pattern `'test%'':

     SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA LIKE 'test%';

For a query that is limited to a specific constant table name, checks
need be made only for the named table within the corresponding database
directory. Example:

     SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA = 'test' AND TABLE_NAME = 't1';

Use of the literal table name `t1' enables the server to check only the
files for the `t1' table, regardless of how many tables there might be
in the `test' database. By contrast, the following query requires a
scan of the `test' database directory to determine which table names
match the pattern `'t%'':

     SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA = 'test' AND TABLE_NAME LIKE 't%';

The following query requires a scan of the database directory to
determine matching database names for the pattern `'test%'', and for
each matching database, it requires a scan of the database directory to
determine matching table names for the pattern `'t%'':

     SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA = 'test%' AND TABLE_NAME LIKE 't%';

*2) Write queries that minimize the number of table files that must be
opened*

For queries that refer to certain `INFORMATION_SCHEMA' table columns,
several optimizations are available that minimize the number of table
files that must be opened. Example:

     SELECT TABLE_NAME, ENGINE FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA = 'test';

In this case, after the server has scanned the database directory to
determine the names of the tables in the database, those names become
available with no further file system lookups. Thus, `TABLE_NAME'
requires no files to be opened. The `ENGINE' (storage engine) value can
be determined by opening the table's `.frm' file, without touching
other table files such as the `.MYD' or `.MYI' file.

Some values, such as `INDEX_LENGTH' for `MyISAM' tables, require
opening the `.MYD' or `.MYI' file as well.

The file-opening optimization types are denoted thus:

   * `SKIP_OPEN_TABLE': Table files do not need to be opened. The
     information has already become available within the query by
     scanning the database directory.

   * `OPEN_FRM_ONLY': Only the table's `.frm' file need be opened.

   * `OPEN_TRIGGER_ONLY': Only the table's `.TRG' file need be opened.

   * `OPEN_FULL_TABLE': The unoptimized information lookup. The `.frm',
     `.MYD', and `.MYI' files must be opened.

The following list indicates how the preceding optimization types apply
to `INFORMATION_SCHEMA' table columns. For tables and columns not
named, none of the optimizations apply.

   * *Note `COLUMNS': columns-table.: `OPEN_FRM_ONLY' applies to all
     columns

   * *Note `KEY_COLUMN_USAGE': key-column-usage-table.:
     `OPEN_FULL_TABLE' applies to all columns

   * *Note `PARTITIONS': partitions-table.: `OPEN_FULL_TABLE' applies
     to all columns

   * *Note `REFERENTIAL_CONSTRAINTS': referential-constraints-table.:
     `OPEN_FULL_TABLE' applies to all columns

   * *Note `STATISTICS': statistics-table.:

     *Column*                           *Optimization type*
     `TABLE_CATALOG'                    `OPEN_FRM_ONLY'
     `TABLE_SCHEMA'                     `OPEN_FRM_ONLY'
     `TABLE_NAME'                       `OPEN_FRM_ONLY'
     `NON_UNIQUE'                       `OPEN_FRM_ONLY'
     `INDEX_SCHEMA'                     `OPEN_FRM_ONLY'
     `INDEX_NAME'                       `OPEN_FRM_ONLY'
     `SEQ_IN_INDEX'                     `OPEN_FRM_ONLY'
     `COLUMN_NAME'                      `OPEN_FRM_ONLY'
     `COLLATION'                        `OPEN_FRM_ONLY'
     `CARDINALITY'                      `OPEN_FULL_TABLE'
     `SUB_PART'                         `OPEN_FRM_ONLY'
     `PACKED'                           `OPEN_FRM_ONLY'
     `NULLABLE'                         `OPEN_FRM_ONLY'
     `INDEX_TYPE'                       `OPEN_FULL_TABLE'
     `COMMENT'                          `OPEN_FRM_ONLY'

   * *Note `TABLES': tables-table.:

     *Column*                           *Optimization type*
     `TABLE_CATALOG'                    `SKIP_OPEN_TABLE'
     `TABLE_SCHEMA'                     `SKIP_OPEN_TABLE'
     `TABLE_NAME'                       `SKIP_OPEN_TABLE'
     `TABLE_TYPE'                       `OPEN_FRM_ONLY'
     `ENGINE'                           `OPEN_FRM_ONLY'
     `VERSION'                          `OPEN_FRM_ONLY'
     `ROW_FORMAT'                       `OPEN_FULL_TABLE'
     `TABLE_ROWS'                       `OPEN_FULL_TABLE'
     `AVG_ROW_LENGTH'                   `OPEN_FULL_TABLE'
     `DATA_LENGTH'                      `OPEN_FULL_TABLE'
     `MAX_DATA_LENGTH'                  `OPEN_FULL_TABLE'
     `INDEX_LENGTH'                     `OPEN_FULL_TABLE'
     `DATA_FREE'                        `OPEN_FULL_TABLE'
     `AUTO_INCREMENT'                   `OPEN_FULL_TABLE'
     `CREATE_TIME'                      `OPEN_FULL_TABLE'
     `UPDATE_TIME'                      `OPEN_FULL_TABLE'
     `CHECK_TIME'                       `OPEN_FULL_TABLE'
     `TABLE_COLLATION'                  `OPEN_FRM_ONLY'
     `CHECKSUM'                         `OPEN_FULL_TABLE'
     `CREATE_OPTIONS'                   `OPEN_FRM_ONLY'
     `TABLE_COMMENT'                    `OPEN_FRM_ONLY'

   * *Note `TABLE_CONSTRAINTS': table-constraints-table.:
     `OPEN_FULL_TABLE' applies to all columns

   * *Note `TRIGGERS': triggers-table.: `OPEN_TRIGGER_ONLY' applies to
     all columns

   * *Note `VIEWS': views-table.:

     *Column*                           *Optimization type*
     `TABLE_CATALOG'                    `OPEN_FRM_ONLY'
     `TABLE_SCHEMA'                     `OPEN_FRM_ONLY'
     `TABLE_NAME'                       `OPEN_FRM_ONLY'
     `VIEW_DEFINITION'                  `OPEN_FRM_ONLY'
     `CHECK_OPTION'                     `OPEN_FRM_ONLY'
     `IS_UPDATABLE'                     `OPEN_FULL_TABLE'
     `DEFINER'                          `OPEN_FRM_ONLY'
     `SECURITY_TYPE'                    `OPEN_FRM_ONLY'
     `CHARACTER_SET_CLIENT'             `OPEN_FRM_ONLY'
     `COLLATION_CONNECTION'             `OPEN_FRM_ONLY'

*3) Use *Note `EXPLAIN': explain. to determine whether the server can
use `INFORMATION_SCHEMA' optimizations for a query*

The `Extra' value in *Note `EXPLAIN': explain. output indicates which,
if any, of the optimizations described earlier the server can use to
evaluate `INFORMATION_SCHEMA' queries.  The following examples
demonstrate the kinds of information you can expect to see in the
`Extra' value.

     mysql> EXPLAIN SELECT TABLE_NAME FROM INFORMATION_SCHEMA.VIEWS WHERE
         -> TABLE_SCHEMA = 'test' AND TABLE_NAME = 'v1'\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: VIEWS
              type: ALL
     possible_keys: NULL
               key: TABLE_SCHEMA,TABLE_NAME
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra: Using where; Open_frm_only; Scanned 0 databases

Use of constant database and table lookup values enables the server to
avoid directory scans. For references to `VIEWS.TABLE_NAME', only the
`.frm' file need be opened.

     mysql> EXPLAIN SELECT TABLE_NAME, ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: TABLES
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra: Open_full_table; Scanned all databases

No lookup values are provided (there is no `WHERE' clause), so the
server must scan the data directory and each database directory. For
each table thus identified, the table name and row format are selected.
`TABLE_NAME' requires no further table files to be opened (the
`SKIP_OPEN_TABLE' optimization applies). `ROW_FORMAT' requires all
table files to be opened (`OPEN_FULL_TABLE' applies).  *Note `EXPLAIN':
explain. reports `OPEN_FULL_TABLE' because it is more expensive than
`SKIP_OPEN_TABLE'.

     mysql> EXPLAIN SELECT TABLE_NAME, TABLE_TYPE FROM INFORMATION_SCHEMA.TABLES
         -> WHERE TABLE_SCHEMA = 'test'\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: TABLES
              type: ALL
     possible_keys: NULL
               key: TABLE_SCHEMA
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra: Using where; Open_frm_only; Scanned 1 database

No table name lookup value is provided, so the server must scan the
`test' database directory. For the `TABLE_NAME' and `TABLE_TYPE'
columns, the `SKIP_OPEN_TABLE' and `OPEN_FRM_ONLY' optimizations apply,
respectively. *Note `EXPLAIN': explain. reports `OPEN_FRM_ONLY' because
it is more expensive.

     mysql> EXPLAIN SELECT B.TABLE_NAME
         -> FROM INFORMATION_SCHEMA.TABLES AS A, INFORMATION_SCHEMA.COLUMNS AS B
         -> WHERE A.TABLE_SCHEMA = 'test'
         -> AND A.TABLE_NAME = 't1'
         -> AND B.TABLE_NAME = A.TABLE_NAME\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: A
              type: ALL
     possible_keys: NULL
               key: TABLE_SCHEMA,TABLE_NAME
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra: Using where; Skip_open_table; Scanned 0 databases
     *************************** 2. row ***************************
                id: 1
       select_type: SIMPLE
             table: B
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra: Using where; Open_frm_only; Scanned all databases;
                    Using join buffer

For the first *Note `EXPLAIN': explain. output row: Constant database
and table lookup values enable the server to avoid directory scans for
`TABLES' values.  References to `TABLES.TABLE_NAME' require no further
table files.

For the second *Note `EXPLAIN': explain. output row: All *Note
`COLUMNS': columns-table. table values are `OPEN_FRM_ONLY' lookups, so
`COLUMNS.TABLE_NAME' requires the `.frm' file to be opened.

     mysql> EXPLAIN SELECT * FROM INFORMATION_SCHEMA.COLLATIONS\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: COLLATIONS
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra:

In this case, no optimizations apply because *Note `COLLATIONS':
collations-table. is not one of the `INFORMATION_SCHEMA' tables for
which optimizations are available.


File: manual.info,  Node: insert-speed,  Next: update-speed,  Prev: information-schema-optimization,  Up: query-speed

7.2.24 Speed of `INSERT' Statements
-----------------------------------

The time required for inserting a row is determined by the following
factors, where the numbers indicate approximate proportions:

   * Connecting: (3)

   * Sending query to server: (2)

   * Parsing query: (2)

   * Inserting row: (1 x size of row)

   * Inserting indexes: (1 x number of indexes)

   * Closing: (1)

This does not take into consideration the initial overhead to open
tables, which is done once for each concurrently running query.

The size of the table slows down the insertion of indexes by log N,
assuming B-tree indexes.

You can use the following methods to speed up inserts:

   * If you are inserting many rows from the same client at the same
     time, use *Note `INSERT': insert.  statements with multiple
     `VALUES' lists to insert several rows at a time. This is
     considerably faster (many times faster in some cases) than using
     separate single-row *Note `INSERT': insert. statements.  If you
     are adding data to a non-empty table, you can tune the
     `bulk_insert_buffer_size' variable to make data insertion even
     faster. See *Note server-system-variables::.

   * If multiple clients are inserting a lot of rows, you can get
     higher speed by using the *Note `INSERT DELAYED': insert-delayed.
     statement. See *Note insert-delayed::.

   * For a `MyISAM' table, you can use concurrent inserts to add rows
     at the same time that *Note `SELECT': select. statements are
     running, if there are no deleted rows in middle of the data file.
     See *Note concurrent-inserts::.

   * When loading a table from a text file, use *Note `LOAD DATA
     INFILE': load-data. This is usually 20 times faster than using
     *Note `INSERT': insert. statements. See *Note load-data::.

   * With some extra work, it is possible to make *Note `LOAD DATA
     INFILE': load-data. run even faster for a `MyISAM' table when the
     table has many indexes. Use the following procedure:

       1. Optionally create the table with *Note `CREATE TABLE':
          create-table.

       2. Execute a *Note `FLUSH TABLES': flush. statement or a *Note
          `mysqladmin flush-tables': mysqladmin. command.

       3. Use *Note `myisamchk --keys-used=0 -rq
          /PATH/TO/DB/TBL_NAME.': myisamchk.  This removes all use of
          indexes for the table.

       4. Insert data into the table with *Note `LOAD DATA INFILE':
          load-data. This does not update any indexes and therefore is
          very fast.

       5. If you intend only to read from the table in the future, use
          *Note `myisampack': myisampack. to compress it. See *Note
          compressed-format::.

       6. Re-create the indexes with *Note `myisamchk -rq
          /PATH/TO/DB/TBL_NAME': myisamchk.  This creates the index
          tree in memory before writing it to disk, which is much
          faster that updating the index during *Note `LOAD DATA
          INFILE': load-data. because it avoids lots of disk seeks. The
          resulting index tree is also perfectly balanced.

       7. Execute a *Note `FLUSH TABLES': flush. statement or a *Note
          `mysqladmin flush-tables': mysqladmin. command.

     *Note `LOAD DATA INFILE': load-data. performs the preceding
     optimization automatically if the `MyISAM' table into which you
     insert data is empty. The main difference between automatic
     optimization and using the procedure explicitly is that you can
     let *Note `myisamchk': myisamchk. allocate much more temporary
     memory for the index creation than you might want the server to
     allocate for index re-creation when it executes the *Note `LOAD
     DATA INFILE': load-data. statement.

     You can also disable or enable the non-unique indexes for a
     `MyISAM' table by using the following statements rather than *Note
     `myisamchk': myisamchk. If you use these statements, you can skip
     the *Note `FLUSH TABLE': flush.  operations:

          ALTER TABLE TBL_NAME DISABLE KEYS;
          ALTER TABLE TBL_NAME ENABLE KEYS;

   * To speed up *Note `INSERT': insert. operations that are performed
     with multiple statements for non-transactional tables, lock your
     tables:

          LOCK TABLES a WRITE;
          INSERT INTO a VALUES (1,23),(2,34),(4,33);
          INSERT INTO a VALUES (8,26),(6,29);
          ...
          UNLOCK TABLES;

     This benefits performance because the index buffer is flushed to
     disk only once, after all *Note `INSERT': insert. statements have
     completed. Normally, there would be as many index buffer flushes
     as there are *Note `INSERT': insert.  statements. Explicit locking
     statements are not needed if you can insert all rows with a single
     *Note `INSERT': insert.

     To obtain faster insertions for transactional tables, you should
     use *Note `START TRANSACTION': commit. and *Note `COMMIT': commit.
     instead of *Note `LOCK TABLES': lock-tables.

     Locking also lowers the total time for multiple-connection tests,
     although the maximum wait time for individual connections might go
     up because they wait for locks. Suppose that five clients attempt
     to perform inserts simultaneously as follows:

        * Connection 1 does 1000 inserts

        * Connections 2, 3, and 4 do 1 insert

        * Connection 5 does 1000 inserts

     If you do not use locking, connections 2, 3, and 4 finish before 1
     and 5. If you use locking, connections 2, 3, and 4 probably do not
     finish before 1 or 5, but the total time should be about 40%
     faster.

     *Note `INSERT': insert, *Note `UPDATE': update, and *Note
     `DELETE': delete. operations are very fast in MySQL, but you can
     obtain better overall performance by adding locks around
     everything that does more than about five successive inserts or
     updates. If you do very many successive inserts, you could do a
     *Note `LOCK TABLES': lock-tables. followed by an *Note `UNLOCK
     TABLES': lock-tables. once in a while (each 1,000 rows or so) to
     allow other threads access to the table. This would still result
     in a nice performance gain.

     *Note `INSERT': insert. is still much slower for loading data than
     *Note `LOAD DATA INFILE': load-data, even when using the
     strategies just outlined.

   * To increase performance for `MyISAM' tables, for both *Note `LOAD
     DATA INFILE': load-data. and *Note `INSERT': insert, enlarge the
     key cache by increasing the `key_buffer_size' system variable. See
     *Note server-parameters::.

MySQL Enterprise

For more advice on optimizing the performance of your server, subscribe
to the MySQL Enterprise Monitor. Numerous advisors are dedicated to
monitoring performance. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: update-speed,  Next: delete-speed,  Prev: insert-speed,  Up: query-speed

7.2.25 Speed of `UPDATE' Statements
-----------------------------------

An update statement is optimized like a *Note `SELECT': select. query
with the additional overhead of a write. The speed of the write depends
on the amount of data being updated and the number of indexes that are
updated. Indexes that are not changed do not get updated.

Another way to get fast updates is to delay updates and then do many
updates in a row later. Performing multiple updates together is much
quicker than doing one at a time if you lock the table.

For a `MyISAM' table that uses dynamic row format, updating a row to a
longer total length may split the row. If you do this often, it is very
important to use *Note `OPTIMIZE TABLE': optimize-table. occasionally.
See *Note optimize-table::.


File: manual.info,  Node: delete-speed,  Next: miscellaneous-optimization-tips,  Prev: update-speed,  Up: query-speed

7.2.26 Speed of `DELETE' Statements
-----------------------------------

The time required to delete individual rows is exactly proportional to
the number of indexes. To delete rows more quickly, you can increase
the size of the key cache by increasing the `key_buffer_size' system
variable. See *Note server-parameters::.

To delete all rows from a table, `TRUNCATE TABLE TBL_NAME' is faster
than than `DELETE FROM TBL_NAME'. Truncate operations are not
transaction-safe; an error occurs when attempting one in the course of
an active transaction or active table lock. See *Note truncate::.


File: manual.info,  Node: miscellaneous-optimization-tips,  Prev: delete-speed,  Up: query-speed

7.2.27 Other Optimization Tips
------------------------------

This section lists a number of miscellaneous tips for improving query
processing speed:

   * Use persistent connections to the database to avoid connection
     overhead. If you cannot use persistent connections and you are
     initiating many new connections to the database, you may want to
     change the value of the `thread_cache_size' variable.  See *Note
     server-parameters::.

   * Always check whether all your queries really use the indexes that
     you have created in the tables. In MySQL, you can do this with the
     *Note `EXPLAIN': explain.  statement. See *Note using-explain::.

   * Try to avoid complex *Note `SELECT': select.  queries on `MyISAM'
     tables that are updated frequently, to avoid problems with table
     locking that occur due to contention between readers and writers.

   * `MyISAM' supports concurrent inserts: If a table has no free
     blocks in the middle of the data file, you can *Note `INSERT':
     insert. new rows into it at the same time that other threads are
     reading from the table. If it is important to be able to do this,
     you should consider using the table in ways that avoid deleting
     rows.  Another possibility is to run *Note `OPTIMIZE TABLE':
     optimize-table. to defragment the table after you have deleted a
     lot of rows from it. This behavior is altered by setting the
     `concurrent_insert' variable.  You can force new rows to be
     appended (and therefore allow concurrent inserts), even in tables
     that have deleted rows.  See *Note concurrent-inserts::.

     MySQL Enterprise

     For optimization tips geared to your specific circumstances
     subscribe to the MySQL Enterprise Monitor.  For more information,
     see `http://www.mysql.com/products/enterprise/advisors.html'.

   * To fix any compression issues that may have occurred with
     `ARCHIVE' tables, you can use *Note `OPTIMIZE TABLE':
     optimize-table. See *Note archive-storage-engine::.

   * Use `ALTER TABLE ... ORDER BY EXPR1, EXPR2, ...' if you usually
     retrieve rows in `EXPR1, EXPR2, ...' order. By using this option
     after extensive changes to the table, you may be able to get
     higher performance.

   * In some cases, it may make sense to introduce a column that is
     `hashed' based on information from other columns. If this column
     is short, reasonably unique, and indexed, it may be much faster
     than a `wide' index on many columns. In MySQL, it is very easy to
     use this extra column:

          SELECT * FROM TBL_NAME
            WHERE HASH_COL=MD5(CONCAT(COL1,COL2))
            AND COL1='CONSTANT' AND COL2='CONSTANT';

   * For `MyISAM' tables that change frequently, you should try to
     avoid all variable-length columns (*Note `VARCHAR': char, *Note
     `BLOB': blob, and *Note `TEXT': blob.). The table uses dynamic row
     format if it includes even a single variable-length column. See
     *Note storage-engines::.

   * It is normally not useful to split a table into different tables
     just because the rows become large. In accessing a row, the
     biggest performance hit is the disk seek needed to find the first
     byte of the row. After finding the data, most modern disks can
     read the entire row fast enough for most applications. The only
     cases where splitting up a table makes an appreciable difference
     is if it is a `MyISAM' table using dynamic row format that you can
     change to a fixed row size, or if you very often need to scan the
     table but do not need most of the columns. See *Note
     storage-engines::.

   * If you often need to calculate results such as counts based on
     information from a lot of rows, it may be preferable to introduce
     a new table and update the counter in real time.  An update of the
     following form is very fast:

          UPDATE TBL_NAME SET COUNT_COL=COUNT_COL+1 WHERE KEY_COL=CONSTANT;

     This is very important when you use MySQL storage engines such as
     `MyISAM' that has only table-level locking (multiple readers with
     single writers). This also gives better performance with most
     database systems, because the row locking manager in this case has
     less to do.

   * If you need to collect statistics from large log tables, use
     summary tables instead of scanning the entire log table.
     Maintaining the summaries should be much faster than trying to
     calculate statistics `live.' Regenerating new summary tables from
     the logs when things change (depending on business decisions) is
     faster than changing the running application.

   * If possible, you should classify reports as `live' or as
     `statistical,' where data needed for statistical reports is
     created only from summary tables that are generated periodically
     from the live data.

   * Take advantage of the fact that columns have default values.
     Insert values explicitly only when the value to be inserted
     differs from the default. This reduces the parsing that MySQL must
     do and improves the insert speed.

   * In some cases, it is convenient to pack and store data into a
     *Note `BLOB': blob. column. In this case, you must provide code in
     your application to pack and unpack information, but this may save
     a lot of accesses at some stage. This is practical when you have
     data that does not conform well to a rows-and-columns table
     structure.

   * Normally, you should try to keep all data non-redundant (observing
     what is referred to in database theory as _third normal form_).
     However, there may be situations in which it can be advantageous to
     duplicate information or create summary tables to gain more speed.

   * Stored routines or UDFs (user-defined functions) may be a good way
     to gain performance for some tasks. See *Note stored-routines::,
     and *Note adding-functions::, for more information.

   * You can increase performance by caching queries or answers in your
     application and then executing many inserts or updates together.
     If your database system supports table locks (as do MySQL), this
     should help to ensure that the index cache is only flushed once
     after all updates. You can also take advantage of MySQL's query
     cache to achieve similar results; see *Note query-cache::.

   * Use *Note `INSERT DELAYED': insert-delayed. when you do not need
     to know when your data is written. This reduces the overall
     insertion impact because many rows can be written with a single
     disk write.

   * Use `INSERT LOW_PRIORITY' when you want to give *Note `SELECT':
     select. statements higher priority than your inserts.

     Use `SELECT HIGH_PRIORITY' to get retrievals that jump the queue.
     That is, the *Note `SELECT': select. is executed even if there is
     another client waiting to do a write.

     `LOW_PRIORITY' and `HIGH_PRIORITY' have an effect only for storage
     engines that use only table-level locking (`MyISAM', `MEMORY',
     `MERGE').

   * Use multiple-row *Note `INSERT': insert.  statements to store many
     rows with one SQL statement. Many SQL servers support this,
     including MySQL.

   * Use *Note `LOAD DATA INFILE': load-data. to load large amounts of
     data. This is faster than using *Note `INSERT': insert.
     statements.

   * Use `AUTO_INCREMENT' columns so that each row in a table can be
     identified by a single unique value.  unique values.

   * Use *Note `OPTIMIZE TABLE': optimize-table. once in a while to
     avoid fragmentation with dynamic-format `MyISAM' tables. See *Note
     myisam-table-formats::.

   * Use `MEMORY' tables when possible to get more speed. See *Note
     memory-storage-engine::.  `MEMORY' tables are useful for
     non-critical data that is accessed often, such as information
     about the last displayed banner for users who don't have cookies
     enabled in their Web browser. User sessions are another
     alternative available in many Web application environments for
     handling volatile state data.

   * With Web servers, images and other binary assets should normally
     be stored as files. That is, store only a reference to the file
     rather than the file itself in the database.  Most Web servers are
     better at caching files than database contents, so using files is
     generally faster.

   * Columns with identical information in different tables should be
     declared to have identical data types so that joins based on the
     corresponding columns will be faster.

   * Try to keep column names simple. For example, in a table named
     `customer', use a column name of `name' instead of
     `customer_name'. To make your names portable to other SQL servers,
     you should keep them shorter than 18 characters.

   * If you need really high speed, you should take a look at the
     low-level interfaces for data storage that the different SQL
     servers support. For example, by accessing the MySQL `MyISAM'
     storage engine directly, you could get a speed increase of two to
     five times compared to using the SQL interface. To be able to do
     this, the data must be on the same server as the application, and
     usually it should only be accessed by one process (because
     external file locking is really slow). One could eliminate these
     problems by introducing low-level `MyISAM' commands in the MySQL
     server (this could be one easy way to get more performance if
     needed). By carefully designing the database interface, it should
     be quite easy to support this type of optimization.

   * If you are using numerical data, it is faster in many cases to
     access information from a database (using a live connection) than
     to access a text file. Information in the database is likely to be
     stored in a more compact format than in the text file, so
     accessing it involves fewer disk accesses. You also save code in
     your application because you need not parse your text files to
     find line and column boundaries.

   * Replication can provide a performance benefit for some operations.
     You can distribute client retrievals among replication servers to
     split up the load. To avoid slowing down the master while making
     backups, you can make backups using a slave server. See *Note
     replication::.

   * Declaring a `MyISAM' table with the `DELAY_KEY_WRITE=1' table
     option makes index updates faster because they are not flushed to
     disk until the table is closed. The downside is that if something
     kills the server while such a table is open, you should ensure
     that the table is okay by running the server with the
     `--myisam-recover' option, or by running *Note `myisamchk':
     myisamchk. before restarting the server. (However, even in this
     case, you should not lose anything by using `DELAY_KEY_WRITE',
     because the key information can always be generated from the data
     rows.)


File: manual.info,  Node: locking-issues,  Next: optimizing-database-structure,  Prev: query-speed,  Up: optimization

7.3 Locking Issues
==================

* Menu:

* internal-locking::             Internal Locking Methods
* table-locking::                Table Locking Issues
* concurrent-inserts::           Concurrent Inserts
* external-locking::             External Locking

MySQL manages contention for table contents using locking:

   * Internal locking is performed within the MySQL server itself to
     manage contention for table contents by multiple threads.  This
     type of locking is internal because it is performed entirely by
     the server and involves no other programs. See *Note
     internal-locking::.

   * External locking occurs when the server and other programs lock
     table files to coordinate among themselves which program can
     access the tables at which time. See *Note external-locking::.


File: manual.info,  Node: internal-locking,  Next: table-locking,  Prev: locking-issues,  Up: locking-issues

7.3.1 Internal Locking Methods
------------------------------

This section discusses internal locking; that is, locking performed
within the MySQL server itself to manage contention for table contents
by multiple threads. This type of locking is internal because it is
performed entirely by the server and involves no other programs.
External locking occurs when the server and other programs lock table
files to coordinate among themselves which program can access the
tables at which time.  See *Note external-locking::.

MySQL uses table-level locking for `MyISAM' and `MEMORY' tables, and
row-level locking for `InnoDB' tables.

In many cases, you can make an educated guess about which locking type
is best for an application, but generally it is difficult to say that a
given lock type is better than another.  Everything depends on the
application and different parts of an application may require different
lock types.

To decide whether you want to use a storage engine with row-level
locking, you should look at what your application does and what mix of
select and update statements it uses. For example, most Web
applications perform many selects, relatively few deletes, updates
based mainly on key values, and inserts into a few specific tables. The
base MySQL `MyISAM' setup is very well tuned for this.

MySQL Enterprise

The MySQL Enterprise Monitor provides expert advice on when to use
table-level locking and when to use row-level locking. To subscribe see
`http://www.mysql.com/products/enterprise/advisors.html'.

Table locking in MySQL is deadlock-free for storage engines that use
table-level locking. Deadlock avoidance is managed by always requesting
all needed locks at once at the beginning of a query and always locking
the tables in the same order.

MySQL grants table write locks as follows:

  1. If there are no locks on the table, put a write lock on it.

  2. Otherwise, put the lock request in the write lock queue.

MySQL grants table read locks as follows:

  1. If there are no write locks on the table, put a read lock on it.

  2. Otherwise, put the lock request in the read lock queue.

When a lock is released, the lock is made available to the requests in
the write lock queue and then to the requests in the read lock queue.
This means that if you have many updates for a table, *Note `SELECT':
select. statements wait until there are no more updates.

You can analyze the table lock contention on your system by checking the
`Table_locks_immediate' and `Table_locks_waited' status variables,
which indicate the number of times that requests for table locks could
be granted immediately and the number that had to wait, respectively:

     mysql> SHOW STATUS LIKE 'Table%';
     +-----------------------+---------+
     | Variable_name         | Value   |
     +-----------------------+---------+
     | Table_locks_immediate | 1151552 |
     | Table_locks_waited    | 15324   |
     +-----------------------+---------+

The `MyISAM' storage engine supports concurrent inserts to reduce
contention between readers and writers for a given table: If a `MyISAM'
table has no free blocks in the middle of the data file, rows are
always inserted at the end of the data file. In this case, you can
freely mix concurrent *Note `INSERT': insert. and *Note `SELECT':
select. statements for a `MyISAM' table without locks. That is, you can
insert rows into a `MyISAM' table at the same time other clients are
reading from it. Holes can result from rows having been deleted from or
updated in the middle of the table. If there are holes, concurrent
inserts are disabled but are re-enabled automatically when all holes
have been filled with new data.. This behavior is altered by the
`concurrent_insert' system variable. See *Note concurrent-inserts::.

If you acquire a table lock explicitly with *Note `LOCK TABLES':
lock-tables, you can request a `READ LOCAL' lock rather than a `READ'
lock to enable other sessions to perform concurrent inserts while you
have the table locked.

To perform many *Note `INSERT': insert. and *Note `SELECT': select.
operations on a table `real_table' when concurrent inserts are not
possible, you can insert rows into a temporary table `temp_table' and
update the real table with the rows from the temporary table
periodically. This can be done with the following code:

     mysql> LOCK TABLES real_table WRITE, temp_table WRITE;
     mysql> INSERT INTO real_table SELECT * FROM temp_table;
     mysql> DELETE FROM temp_table;
     mysql> UNLOCK TABLES;

`InnoDB' uses row locks. Deadlocks are possible for `InnoDB' because it
automatically acquires locks during the processing of SQL statements,
not at the start of the transaction.

Advantages of row-level locking:

   * Fewer lock conflicts when different sessions access different rows

   * Fewer changes for rollbacks

   * Possible to lock a single row for a long time

Disadvantages of row-level locking:

   * Requires more memory than table-level locks

   * Slower than table-level locks when used on a large part of the
     table because you must acquire many more locks

   * Definitely much slower than other locks if you often do `GROUP BY'
     operations on a large part of the data or if you must scan the
     entire table frequently

Table locks are superior to row-level locks in the following cases:

   * Most statements for the table are reads

   * Statements for the table are a mix of reads and writes, where
     writes are updates or deletes for a single row that can be fetched
     with one key read:

          UPDATE TBL_NAME SET COLUMN=VALUE WHERE UNIQUE_KEY_COL=KEY_VALUE;
          DELETE FROM TBL_NAME WHERE UNIQUE_KEY_COL=KEY_VALUE;

   * *Note `SELECT': select. combined with concurrent *Note `INSERT':
     insert. statements, and very few *Note `UPDATE': update. or *Note
     `DELETE': delete. statements

   * Many scans or `GROUP BY' operations on the entire table without
     any writers

With higher-level locks, you can more easily tune applications by
supporting locks of different types, because the lock overhead is less
than for row-level locks.

Options other than row-level locking:

   * Versioning (such as that used in MySQL for concurrent inserts)
     where it is possible to have one writer at the same time as many
     readers. This means that the database or table supports different
     views for the data depending on when access begins. Other common
     terms for this are `time travel,' `copy on write,' or `copy on
     demand.'

   * Copy on demand is in many cases superior to row-level locking.
     However, in the worst case, it can use much more memory than using
     normal locks.

   * Instead of using row-level locks, you can employ application-level
     locks, such as those provided by `GET_LOCK()' and `RELEASE_LOCK()'
     in MySQL.  These are advisory locks, so they work only with
     applications that cooperate with each other. See *Note
     miscellaneous-functions::.


File: manual.info,  Node: table-locking,  Next: concurrent-inserts,  Prev: internal-locking,  Up: locking-issues

7.3.2 Table Locking Issues
--------------------------

To achieve a very high lock speed, MySQL uses table locking (instead of
page, row, or column locking) for all storage engines except `InnoDB'.

For `InnoDB' tables, MySQL only uses table locking if you explicitly
lock the table with *Note `LOCK TABLES': lock-tables. For these storage
engines, we recommend that you not use *Note `LOCK TABLES':
lock-tables. at all, because `InnoDB' uses automatic row-level locking
to ensure transaction isolation.

For large tables, table locking is much better than row locking for
most applications, but there are some disadvantages:

   * Table locking enables many threads to read from a table at the
     same time, but if a thread wants to write to a table, it must
     first get exclusive access. During the update, all other threads
     that want to access this particular table must wait until the
     update is done.

   * Table updates normally are considered to be more important than
     table retrievals, so they are given higher priority.  This should
     ensure that updates to a table are not `starved' even if there is
     heavy *Note `SELECT': select. activity for the table.

   * Table locking causes problems in cases such as when a thread is
     waiting because the disk is full and free space needs to become
     available before the thread can proceed. In this case, all threads
     that want to access the problem table are also put in a waiting
     state until more disk space is made available.

Table locking is also disadvantageous under the following scenario:

   * A client issues a *Note `SELECT': select. that takes a long time
     to run.

   * Another client then issues an *Note `UPDATE': update. on the same
     table.  This client waits until the *Note `SELECT': select. is
     finished.

   * Another client issues another *Note `SELECT': select. statement on
     the same table. Because *Note `UPDATE': update. has higher
     priority than *Note `SELECT': select, this *Note `SELECT': select.
     waits for the *Note `UPDATE': update. to finish, _and_ for the
     first *Note `SELECT': select. to finish.

The following items describe some ways to avoid or reduce contention
caused by table locking:

   * Try to get the *Note `SELECT': select.  statements to run faster
     so that they lock tables for a shorter time. You might have to
     create some summary tables to do this.

   * Start *Note `mysqld': mysqld. with `--low-priority-updates'. For
     storage engines that use only table-level locking (`MyISAM',
     `MEMORY', `MERGE'), this gives all statements that update (modify)
     a table lower priority than *Note `SELECT': select. statements. In
     this case, the second *Note `SELECT': select.  statement in the
     preceding scenario would execute before the *Note `UPDATE':
     update. statement, and would not need to wait for the first *Note
     `SELECT': select. to finish.

   * You can specify that all updates issued in a specific connection
     should be done with low priority by using the `SET
     LOW_PRIORITY_UPDATES=1' statement. See *Note
     server-session-variables::.

   * You can give a specific *Note `INSERT': insert, *Note `UPDATE':
     update, or *Note `DELETE': delete. statement lower priority with
     the `LOW_PRIORITY' attribute.

   * You can give a specific *Note `SELECT': select. statement higher
     priority with the `HIGH_PRIORITY' attribute. See *Note select::.

   * You can start *Note `mysqld': mysqld. with a low value for the
     `max_write_lock_count' system variable to force MySQL to
     temporarily elevate the priority of all *Note `SELECT': select.
     statements that are waiting for a table after a specific number of
     inserts to the table occur. This allows `READ' locks after a
     certain number of `WRITE' locks.

   * If you have problems with *Note `INSERT': insert. combined with
     *Note `SELECT': select, you might want to consider switching to
     `MyISAM' tables, which support concurrent *Note `SELECT': select.
     and *Note `INSERT': insert. statements. (See *Note
     concurrent-inserts::.)

   * If you mix inserts and deletes on the same table, *Note `INSERT
     DELAYED': insert-delayed. may be of great help. See *Note
     insert-delayed::.

   * If you have problems with mixed *Note `SELECT': select. and *Note
     `DELETE': delete. statements, the `LIMIT' option to *Note
     `DELETE': delete. may help. See *Note delete::.

   * Using `SQL_BUFFER_RESULT' with *Note `SELECT': select. statements
     can help to make the duration of table locks shorter. See *Note
     select::.

   * You could change the locking code in `mysys/thr_lock.c' to use a
     single queue.  In this case, write locks and read locks would have
     the same priority, which might help some applications.

Here are some tips concerning table locks in MySQL:

   * Concurrent users are not a problem if you do not mix updates with
     selects that need to examine many rows in the same table.

   * You can use *Note `LOCK TABLES': lock-tables. to increase speed,
     because many updates within a single lock is much faster than
     updating without locks. Splitting table contents into separate
     tables may also help.

   * If you encounter speed problems with table locks in MySQL, you may
     be able to improve performance by converting some of your tables
     to `InnoDB'. See *Note innodb::.

     MySQL Enterprise

     Lock contention can seriously degrade performance. The MySQL
     Enterprise Monitor provides expert advice on avoiding this
     problem. To subscribe, see
     `http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: concurrent-inserts,  Next: external-locking,  Prev: table-locking,  Up: locking-issues

7.3.3 Concurrent Inserts
------------------------

The `MyISAM' storage engine supports concurrent inserts to reduce
contention between readers and writers for a given table: If a `MyISAM'
table has no holes in the data file (deleted rows in the middle),
inserts can be performed to add rows to the end of the table at the
same time that *Note `SELECT': select. statements are reading rows from
the table.

The `concurrent_insert' system variable can be set to modify the
concurrent-insert processing.  By default, the variable is set to 1 and
concurrent inserts are handled as just described. If
`concurrent_insert' is set to 0, concurrent inserts are disabled. If
the variable is set to 2, concurrent inserts at the end of the table
are allowed even for tables that have deleted rows. See also the
description of the `concurrent_insert' system variable.

Under circumstances where concurrent inserts can be used, there is
seldom any need to use the `DELAYED' modifier for *Note `INSERT':
insert. statements.  See *Note insert-delayed::.

If you are using the binary log, concurrent inserts are converted to
normal inserts for `CREATE ...  SELECT' or *Note `INSERT ... SELECT':
insert-select. statements. This is done to ensure that you can
re-create an exact copy of your tables by applying the log during a
backup operation. See *Note binary-log::. In addition, for those
statements a read lock is placed on the selected-from table such that
inserts into that table are blocked. The effect is that concurrent
inserts for that table must wait as well.

With *Note `LOAD DATA INFILE': load-data, if you specify `CONCURRENT'
with a `MyISAM' table that satisfies the condition for concurrent
inserts (that is, it contains no free blocks in the middle), other
threads can retrieve data from the table while *Note `LOAD DATA':
load-data. is executing. Use of the `CONCURRENT' option affects the
performance of *Note `LOAD DATA': load-data. a bit, even if no other
thread is using the table at the same time.

If you specify `HIGH_PRIORITY', it overrides the effect of the
`--low-priority-updates' option if the server was started with that
option. It also causes concurrent inserts not to be used.

For *Note `LOCK TABLE': lock-tables, the difference between `READ
LOCAL' and `READ' is that `READ LOCAL' allows non-conflicting *Note
`INSERT': insert. statements (concurrent inserts) to execute while the
lock is held. However, this cannot be used if you are going to
manipulate the database using processes external to the server while
you hold the lock.


File: manual.info,  Node: external-locking,  Prev: concurrent-inserts,  Up: locking-issues

7.3.4 External Locking
----------------------

External locking is the use of file system locking to manage contention
for database tables by multiple processes. External locking is used in
situations where a single process such as the MySQL server cannot be
assumed to be the only process that requires access to tables. Here are
some examples:

   * If you run multiple servers that use the same database directory
     (not recommended), each server must have external locking enabled.

   * If you use *Note `myisamchk': myisamchk. to perform table
     maintenance operations on `MyISAM' tables, you must either ensure
     that the server is not running, or that the server has external
     locking enabled so that it locks table files as necessary to
     coordinate with *Note `myisamchk': myisamchk. for access to the
     tables. The same is true for use of *Note `myisampack':
     myisampack. to pack `MyISAM' tables.

With external locking in effect, each process that requires access to a
table acquires a file system lock for the table files before proceeding
to access the table. If all necessary locks cannot be acquired, the
process is blocked from accessing the table until the locks can be
obtained (after the process that currently holds the locks releases
them).

External locking affects server performance because the server must
sometimes wait for other processes before it can access tables.

External locking is unnecessary if you run a single server to access a
given data directory (which is the usual case) and if no other programs
such as *Note `myisamchk': myisamchk. need to modify tables while the
server is running. If you only _read_ tables with other programs,
external locking is not required, although *Note `myisamchk': myisamchk.
might report warnings if the server changes tables while *Note
`myisamchk': myisamchk. is reading them.

With external locking disabled, to use *Note `myisamchk': myisamchk,
you must either stop the server while *Note `myisamchk': myisamchk.
executes or else lock and flush the tables before running *Note
`myisamchk': myisamchk.  (See *Note system-optimization::.) To avoid
this requirement, use the *Note `CHECK TABLE': check-table.  and *Note
`REPAIR TABLE': repair-table. statements to check and repair `MyISAM'
tables.

For *Note `mysqld': mysqld, external locking is controlled by the value
of the `skip_external_locking' system variable. When this variable is
enabled, external locking is disabled, and vice versa. From MySQL 4.0
on, external locking is disabled by default. Before MySQL 4.0, external
locking is enabled by default on Linux or when MySQL is configured to
use MIT-pthreads.

Use of external locking can be controlled at server startup by using
the `--external-locking' or `--skip-external-locking' option.

If you do use external locking option to enable updates to `MyISAM'
tables from many MySQL processes, you must ensure that the following
conditions are satisfied:

   * You should not use the query cache for queries that use tables
     that are updated by another process.

   * You should not start the server with the `--delay-key-write=ALL'
     option or use the `DELAY_KEY_WRITE=1' table option for any shared
     tables. Otherwise, index corruption can occur.

The easiest way to satisfy these conditions is to always use
`--external-locking' together with `--delay-key-write=OFF' and
`--query-cache-size=0'. (This is not done by default because in many
setups it is useful to have a mixture of the preceding options.)


File: manual.info,  Node: optimizing-database-structure,  Next: optimizing-the-server,  Prev: locking-issues,  Up: optimization

7.4 Optimizing Database Structure
=================================

* Menu:

* design::                       Design Choices
* data-size::                    Make Your Data as Small as Possible
* indexes::                      Column Indexes
* multiple-column-indexes::      Multiple-Column Indexes
* mysql-indexes::                How MySQL Uses Indexes
* myisam-key-cache::             The `MyISAM' Key Cache
* myisam-index-statistics::      `MyISAM' Index Statistics Collection
* table-cache::                  How MySQL Opens and Closes Tables
* creating-many-tables::         Disadvantages of Creating Many Tables in the Same Database


File: manual.info,  Node: design,  Next: data-size,  Prev: optimizing-database-structure,  Up: optimizing-database-structure

7.4.1 Design Choices
--------------------

MySQL keeps row data and index data in separate files. Many (almost
all) other database systems mix row and index data in the same file. We
believe that the MySQL choice is better for a very wide range of modern
systems.

Another way to store the row data is to keep the information for each
column in a separate area (examples are SDBM and Focus).  This causes a
performance hit for every query that accesses more than one column.
Because this degenerates so quickly when more than one column is
accessed, we believe that this model is not good for general-purpose
databases.

The more common case is that the index and data are stored together (as
in Oracle/Sybase, et al). In this case, you find the row information at
the leaf page of the index. The good thing with this layout is that it,
in many cases, depending on how well the index is cached, saves a disk
read. The bad things with this layout are:

   * Table scanning is much slower because you have to read through the
     indexes to get at the data.

   * You cannot use only the index table to retrieve data for a query.

   * You use more space because you must duplicate indexes from the
     nodes (you cannot store the row in the nodes).

   * Deletes degenerate the table over time (because indexes in nodes
     are usually not updated on delete).

   * It is more difficult to cache only the index data.


File: manual.info,  Node: data-size,  Next: indexes,  Prev: design,  Up: optimizing-database-structure

7.4.2 Make Your Data as Small as Possible
-----------------------------------------

One of the most basic optimizations is to design your tables to take as
little space on the disk as possible. This can result in huge
improvements because disk reads are faster, and smaller tables normally
require less main memory while their contents are being actively
processed during query execution. Indexing also is a lesser resource
burden if done on smaller columns.

MySQL supports many different storage engines (table types) and row
formats. For each table, you can decide which storage and indexing
method to use. Choosing the proper table format for your application
may give you a big performance gain. See *Note storage-engines::.

You can get better performance for a table and minimize storage space
by using the techniques listed here:

   * Use the most efficient (smallest) data types possible. MySQL has
     many specialized types that save disk space and memory.  For
     example, use the smaller integer types if possible to get smaller
     tables. *Note `MEDIUMINT': numeric-types.  is often a better
     choice than *Note `INT': numeric-types. because a *Note
     `MEDIUMINT': numeric-types. column uses 25% less space.

   * Declare columns to be `NOT NULL' if possible. It makes everything
     faster and you save one bit per column. If you really need `NULL'
     in your application, you should definitely use it. Just avoid
     having it on all columns by default.

   * For `MyISAM' tables, if you do not have any variable-length columns
     (*Note `VARCHAR': char, *Note `TEXT': blob, or *Note `BLOB': blob.
     columns), a fixed-size row format is used. This is faster but
     unfortunately may waste some space. See *Note
     myisam-table-formats::. You can hint that you want to have fixed
     length rows even if you have *Note `VARCHAR': char. columns with
     the *Note `CREATE TABLE': create-table. option `ROW_FORMAT=FIXED'.

   * `InnoDB' tables use a compact storage format. In versions of MySQL
     earlier than 5.0.3, `InnoDB' rows contain some redundant
     information, such as the number of columns and the length of each
     column, even for fixed-size columns. By default, tables are
     created in the compact format (`ROW_FORMAT=COMPACT'). If you wish
     to downgrade to older versions of MySQL, you can request the old
     format with `ROW_FORMAT=REDUNDANT'.

     The presence of the compact row format decreases row storage space
     by about 20% at the cost of increasing CPU use for some
     operations. If your workload is a typical one that is limited by
     cache hit rates and disk speed it is likely to be faster. If it is
     a rare case that is limited by CPU speed, it might be slower.

     The compact `InnoDB' format also changes how *Note `CHAR': char.
     columns containing UTF-8 data are stored. With
     `ROW_FORMAT=REDUNDANT', a UTF-8 `CHAR(N)' occupies 3 x N bytes,
     given that the maximum length of a UTF-8 encoded character is
     three bytes. Many languages can be written primarily using
     single-byte UTF-8 characters, so a fixed storage length often
     wastes space. With `ROW_FORMAT=COMPACT' format, `InnoDB' allocates
     a variable amount of storage in the range from N to 3 x N bytes
     for these columns by stripping trailing spaces if necessary. The
     minimum storage length is kept as N bytes to facilitate in-place
     updates in typical cases.

   * The primary index of a table should be as short as possible.  This
     makes identification of each row easy and efficient.

   * Create only the indexes that you really need. Indexes are good for
     retrieval but bad when you need to store data quickly. If you
     access a table mostly by searching on a combination of columns,
     create an index on them. The first part of the index should be the
     column most used. If you _always_ use many columns when selecting
     from the table, you should use the column with more duplicates
     first to obtain better compression of the index.

   * If it is very likely that a string column has a unique prefix on
     the first number of characters, it is better to index only this
     prefix, using MySQL's support for creating an index on the
     leftmost part of the column (see *Note create-index::). Shorter
     indexes are faster, not only because they require less disk space,
     but because they also give you more hits in the index cache, and
     thus fewer disk seeks. See *Note server-parameters::.

   * In some circumstances, it can be beneficial to split into two a
     table that is scanned very often. This is especially true if it is
     a dynamic-format table and it is possible to use a smaller static
     format table that can be used to find the relevant rows when
     scanning the table.


File: manual.info,  Node: indexes,  Next: multiple-column-indexes,  Prev: data-size,  Up: optimizing-database-structure

7.4.3 Column Indexes
--------------------

All MySQL data types can be indexed. Use of indexes on the relevant
columns is the best way to improve the performance of *Note `SELECT':
select. operations.

The maximum number of indexes per table and the maximum index length is
defined per storage engine. See *Note storage-engines::. All storage
engines support at least 16 indexes per table and a total index length
of at least 256 bytes. Most storage engines have higher limits.

With `COL_NAME(N)' syntax in an index specification, you can create an
index that uses only the first N characters of a string column.
Indexing only a prefix of column values in this way can make the index
file much smaller. When you index a *Note `BLOB': blob. or *Note
`TEXT': blob. column, you _must_ specify a prefix length for the index.
For example:

     CREATE TABLE test (blob_col BLOB, INDEX(blob_col(10)));

Prefixes can be up to 1000 bytes long (767 bytes for `InnoDB' tables).
Note that prefix limits are measured in bytes, whereas the prefix
length in *Note `CREATE TABLE': create-table. statements is interpreted
as number of characters. _Be sure to take this into account when
specifying a prefix length for a column that uses a multi-byte
character set_.

You can also create `FULLTEXT' indexes. These are used for full-text
searches. Only the `MyISAM' storage engine supports `FULLTEXT' indexes
and only for *Note `CHAR': char, *Note `VARCHAR': char, and *Note
`TEXT': blob. columns. Indexing always takes place over the entire
column and column prefix indexing is not supported. For details, see
*Note fulltext-search::.

You can also create indexes on spatial data types. Currently, only
`MyISAM' supports R-tree indexes on spatial types. Other storage
engines use B-trees for indexing spatial types (except for `ARCHIVE',
which does not support spatial type indexing).

The `MEMORY' storage engine uses `HASH' indexes by default, but also
supports `BTREE' indexes.


File: manual.info,  Node: multiple-column-indexes,  Next: mysql-indexes,  Prev: indexes,  Up: optimizing-database-structure

7.4.4 Multiple-Column Indexes
-----------------------------

MySQL can create composite indexes (that is, indexes on multiple
columns). An index may consist of up to 15 columns. For certain data
types, you can index a prefix of the column (see *Note indexes::).

A multiple-column index can be considered a sorted array containing
values that are created by concatenating the values of the indexed
columns.

MySQL uses multiple-column indexes in such a way that queries are fast
when you specify a known quantity for the first column of the index in
a `WHERE' clause, even if you do not specify values for the other
columns.

Suppose that a table has the following specification:

     CREATE TABLE test (
         id         INT NOT NULL,
         last_name  CHAR(30) NOT NULL,
         first_name CHAR(30) NOT NULL,
         PRIMARY KEY (id),
         INDEX name (last_name,first_name)
     );

The `name' index is an index over the `last_name' and `first_name'
columns. The index can be used for queries that specify values in a
known range for `last_name', or for both `last_name' and `first_name'.
Therefore, the `name' index is used in the following queries:

     SELECT * FROM test WHERE last_name='Widenius';

     SELECT * FROM test
       WHERE last_name='Widenius' AND first_name='Michael';

     SELECT * FROM test
       WHERE last_name='Widenius'
       AND (first_name='Michael' OR first_name='Monty');

     SELECT * FROM test
       WHERE last_name='Widenius'
       AND first_name >='M' AND first_name < 'N';

However, the `name' index is _not_ used in the following queries:

     SELECT * FROM test WHERE first_name='Michael';

     SELECT * FROM test
       WHERE last_name='Widenius' OR first_name='Michael';

The manner in which MySQL uses indexes to improve query performance is
discussed further in *Note mysql-indexes::.


File: manual.info,  Node: mysql-indexes,  Next: myisam-key-cache,  Prev: multiple-column-indexes,  Up: optimizing-database-structure

7.4.5 How MySQL Uses Indexes
----------------------------

Indexes are used to find rows with specific column values quickly.
Without an index, MySQL must begin with the first row and then read
through the entire table to find the relevant rows. The larger the
table, the more this costs. If the table has an index for the columns
in question, MySQL can quickly determine the position to seek to in the
middle of the data file without having to look at all the data. If a
table has 1,000 rows, this is at least 100 times faster than reading
sequentially. If you need to access most of the rows, it is faster to
read sequentially, because this minimizes disk seeks.

Most MySQL indexes (`PRIMARY KEY', `UNIQUE', `INDEX', and `FULLTEXT')
are stored in B-trees. Exceptions are that indexes on spatial data
types use R-trees, and that `MEMORY' tables also support hash indexes.

Strings are automatically prefix- and end-space compressed. See *Note
create-index::.

In general, indexes are used as described in the following discussion.
Characteristics specific to hash indexes (as used in `MEMORY' tables)
are described at the end of this section.

MySQL uses indexes for these operations:

   * To find the rows matching a `WHERE' clause quickly.

   * To eliminate rows from consideration. If there is a choice between
     multiple indexes, MySQL normally uses the index that finds the
     smallest number of rows.

   * To retrieve rows from other tables when performing joins.  MySQL
     can use indexes on columns more efficiently if they are declared
     as the same type and size. In this context, *Note `VARCHAR': char.
     and *Note `CHAR': char. are considered the same if they are
     declared as the same size. For example, `VARCHAR(10)' and
     `CHAR(10)' are the same size, but `VARCHAR(10)' and `CHAR(15)' are
     not.

     Comparison of dissimilar columns may prevent use of indexes if
     values cannot be compared directly without conversion.  Suppose
     that a numeric column is compared to a string column. For a given
     value such as `1' in the numeric column, it might compare equal to
     any number of values in the string column such as `'1'', `' 1'',
     `'00001'', or `'01.e1''. This rules out use of any indexes for the
     string column.

   * To find the `MIN()' or `MAX()' value for a specific indexed column
     KEY_COL. This is optimized by a preprocessor that checks whether
     you are using `WHERE KEY_PART_N = CONSTANT' on all key parts that
     occur before KEY_COL in the index. In this case, MySQL does a
     single key lookup for each `MIN()' or `MAX()' expression and
     replaces it with a constant. If all expressions are replaced with
     constants, the query returns at once. For example:

          SELECT MIN(KEY_PART2),MAX(KEY_PART2)
            FROM TBL_NAME WHERE KEY_PART1=10;

   * To sort or group a table if the sorting or grouping is done on a
     leftmost prefix of a usable key (for example, `ORDER BY KEY_PART1,
     KEY_PART2'). If all key parts are followed by `DESC', the key is
     read in reverse order. See *Note order-by-optimization::, and
     *Note group-by-optimization::.

   * In some cases, a query can be optimized to retrieve values without
     consulting the data rows. If a query uses only columns from a
     table that are numeric and that form a leftmost prefix for some
     key, the selected values may be retrieved from the index tree for
     greater speed:

          SELECT KEY_PART3 FROM TBL_NAME
            WHERE KEY_PART1=1

Suppose that you issue the following *Note `SELECT': select. statement:

     mysql> SELECT * FROM TBL_NAME WHERE col1=VAL1 AND col2=VAL2;

If a multiple-column index exists on `col1' and `col2', the appropriate
rows can be fetched directly. If separate single-column indexes exist on
`col1' and `col2', the optimizer will attempt to use the Index Merge
optimization (see *Note index-merge-optimization::), or attempt to find
the most restrictive index by deciding which index finds fewer rows and
using that index to fetch the rows.

If the table has a multiple-column index, any leftmost prefix of the
index can be used by the optimizer to find rows. For example, if you
have a three-column index on `(col1, col2, col3)', you have indexed
search capabilities on `(col1)', `(col1, col2)', and `(col1, col2,
col3)'.

MySQL cannot use an index if the columns do not form a leftmost prefix
of the index. Suppose that you have the *Note `SELECT': select.
statements shown here:

     SELECT * FROM TBL_NAME WHERE col1=VAL1;
     SELECT * FROM TBL_NAME WHERE col1=VAL1 AND col2=VAL2;

     SELECT * FROM TBL_NAME WHERE col2=VAL2;
     SELECT * FROM TBL_NAME WHERE col2=VAL2 AND col3=VAL3;

If an index exists on `(col1, col2, col3)', only the first two queries
use the index. The third and fourth queries do involve indexed columns,
but `(col2)' and `(col2, col3)' are not leftmost prefixes of `(col1,
col2, col3)'.

A B-tree index can be used for column comparisons in expressions that
use the `=', `>', `>=', `<', `<=', or `BETWEEN' operators. The index
also can be used for `LIKE' comparisons if the argument to `LIKE' is a
constant string that does not start with a wildcard character. For
example, the following *Note `SELECT': select. statements use indexes:

     SELECT * FROM TBL_NAME WHERE KEY_COL LIKE 'Patrick%';
     SELECT * FROM TBL_NAME WHERE KEY_COL LIKE 'Pat%_ck%';

In the first statement, only rows with `'Patrick' <= KEY_COL <
'Patricl'' are considered. In the second statement, only rows with
`'Pat' <= KEY_COL < 'Pau'' are considered.

The following *Note `SELECT': select. statements do not use indexes:

     SELECT * FROM TBL_NAME WHERE KEY_COL LIKE '%Patrick%';
     SELECT * FROM TBL_NAME WHERE KEY_COL LIKE OTHER_COL;

In the first statement, the `LIKE' value begins with a wildcard
character. In the second statement, the `LIKE' value is not a constant.

If you use `... LIKE '%STRING%'' and STRING is longer than three
characters, MySQL uses the _Turbo Boyer-Moore algorithm_ to initialize
the pattern for the string and then uses this pattern to perform the
search more quickly.

A search using `COL_NAME IS NULL' employs indexes if COL_NAME is
indexed.

Any index that does not span all `AND' levels in the `WHERE' clause is
not used to optimize the query. In other words, to be able to use an
index, a prefix of the index must be used in every `AND' group.

The following `WHERE' clauses use indexes:

     ... WHERE INDEX_PART1=1 AND INDEX_PART2=2 AND OTHER_COLUMN=3
         /* INDEX = 1 OR INDEX = 2 */
     ... WHERE INDEX=1 OR A=10 AND INDEX=2
         /* optimized like "INDEX_PART1='hello'" */
     ... WHERE INDEX_PART1='hello' AND INDEX_PART3=5
         /* Can use index on INDEX1 but not on INDEX2 or INDEX3 */
     ... WHERE INDEX1=1 AND INDEX2=2 OR INDEX1=3 AND INDEX3=3;

These `WHERE' clauses do _not_ use indexes:

         /* INDEX_PART1 is not used */
     ... WHERE INDEX_PART2=1 AND INDEX_PART3=2

         /*  Index is not used in both parts of the WHERE clause  */
     ... WHERE INDEX=1 OR A=10

         /* No index spans all rows  */
     ... WHERE INDEX_PART1=1 OR INDEX_PART2=10

Sometimes MySQL does not use an index, even if one is available.  One
circumstance under which this occurs is when the optimizer estimates
that using the index would require MySQL to access a very large
percentage of the rows in the table. (In this case, a table scan is
likely to be much faster because it requires fewer seeks.) However, if
such a query uses `LIMIT' to retrieve only some of the rows, MySQL uses
an index anyway, because it can much more quickly find the few rows to
return in the result.

Hash indexes have somewhat different characteristics from those just
discussed:

   * They are used only for equality comparisons that use the `=' or
     `<=>' operators (but are _very_ fast). They are not used for
     comparison operators such as `<' that find a range of values.

   * The optimizer cannot use a hash index to speed up `ORDER BY'
     operations. (This type of index cannot be used to search for the
     next entry in order.)

   * MySQL cannot determine approximately how many rows there are
     between two values (this is used by the range optimizer to decide
     which index to use). This may affect some queries if you change a
     `MyISAM' table to a hash-indexed `MEMORY' table.

   * Only whole keys can be used to search for a row. (With a B-tree
     index, any leftmost prefix of the key can be used to find rows.)

MySQL Enterprise

Often, it is not possible to predict exactly what indexes will be
required or will be most efficient -- actual table usage is the best
indicator. The MySQL Enterprise Monitor provides expert advice on this
topic. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: myisam-key-cache,  Next: myisam-index-statistics,  Prev: mysql-indexes,  Up: optimizing-database-structure

7.4.6 The `MyISAM' Key Cache
----------------------------

* Menu:

* shared-key-cache::             Shared Key Cache Access
* multiple-key-caches::          Multiple Key Caches
* midpoint-insertion::           Midpoint Insertion Strategy
* index-preloading::             Index Preloading
* key-cache-block-size::         Key Cache Block Size
* key-cache-restructuring::      Restructuring a Key Cache

To minimize disk I/O, the `MyISAM' storage engine exploits a strategy
that is used by many database management systems. It employs a cache
mechanism to keep the most frequently accessed table blocks in memory:

   * For index blocks, a special structure called the _key cache_ (or
     _key buffer_) is maintained. The structure contains a number of
     block buffers where the most-used index blocks are placed.

   * For data blocks, MySQL uses no special cache. Instead it relies on
     the native operating system file system cache.

This section first describes the basic operation of the `MyISAM' key
cache. Then it discusses features that improve key cache performance
and that enable you to better control cache operation:

   * Multiple threads can access the cache concurrently.

   * You can set up multiple key caches and assign table indexes to
     specific caches.

To control the size of the key cache, use the `key_buffer_size' system
variable. If this variable is set equal to zero, no key cache is used.
The key cache also is not used if the `key_buffer_size' value is too
small to allocate the minimal number of block buffers (8).

MySQL Enterprise

For expert advice on identifying the optimum size for
`key_buffer_size', subscribe to the MySQL Enterprise Monitor. See
`http://www.mysql.com/products/enterprise/advisors.html'.

When the key cache is not operational, index files are accessed using
only the native file system buffering provided by the operating system.
(In other words, table index blocks are accessed using the same
strategy as that employed for table data blocks.)

An index block is a contiguous unit of access to the `MyISAM' index
files. Usually the size of an index block is equal to the size of nodes
of the index B-tree.  (Indexes are represented on disk using a B-tree
data structure.  Nodes at the bottom of the tree are leaf nodes. Nodes
above the leaf nodes are non-leaf nodes.)

All block buffers in a key cache structure are the same size.  This
size can be equal to, greater than, or less than the size of a table
index block. Usually one these two values is a multiple of the other.

When data from any table index block must be accessed, the server first
checks whether it is available in some block buffer of the key cache.
If it is, the server accesses data in the key cache rather than on
disk. That is, it reads from the cache or writes into it rather than
reading from or writing to disk.  Otherwise, the server chooses a cache
block buffer containing a different table index block (or blocks) and
replaces the data there by a copy of required table index block. As
soon as the new index block is in the cache, the index data can be
accessed.

If it happens that a block selected for replacement has been modified,
the block is considered `dirty.' In this case, prior to being replaced,
its contents are flushed to the table index from which it came.

Usually the server follows an _LRU (Least Recently Used)_ strategy:
When choosing a block for replacement, it selects the least recently
used index block. To make this choice easier, the key cache module
maintains a special queue (_LRU chain_) of all used blocks. When a
block is accessed, it is placed at the end of the queue. When blocks
need to be replaced, blocks at the beginning of the queue are the least
recently used and become the first candidates for eviction.


File: manual.info,  Node: shared-key-cache,  Next: multiple-key-caches,  Prev: myisam-key-cache,  Up: myisam-key-cache

7.4.6.1 Shared Key Cache Access
...............................

Threads can access key cache buffers simultaneously, subject to the
following conditions:

   * A buffer that is not being updated can be accessed by multiple
     threads.

   * A buffer that is being updated causes threads that need to use it
     to wait until the update is complete.

   * Multiple threads can initiate requests that result in cache block
     replacements, as long as they do not interfere with each other
     (that is, as long as they need different index blocks, and thus
     cause different cache blocks to be replaced).

Shared access to the key cache enables the server to improve throughput
significantly.


File: manual.info,  Node: multiple-key-caches,  Next: midpoint-insertion,  Prev: shared-key-cache,  Up: myisam-key-cache

7.4.6.2 Multiple Key Caches
...........................

Shared access to the key cache improves performance but does not
eliminate contention among threads entirely. They still compete for
control structures that manage access to the key cache buffers. To
reduce key cache access contention further, MySQL also provides
multiple key caches. This feature enables you to assign different table
indexes to different key caches.

Where there are multiple key caches, the server must know which cache
to use when processing queries for a given `MyISAM' table. By default,
all `MyISAM' table indexes are cached in the default key cache. To
assign table indexes to a specific key cache, use the *Note `CACHE
INDEX': cache-index.  statement (see *Note cache-index::). For example,
the following statement assigns indexes from the tables `t1', `t2', and
`t3' to the key cache named `hot_cache':

     mysql> CACHE INDEX t1, t2, t3 IN hot_cache;
     +---------+--------------------+----------+----------+
     | Table   | Op                 | Msg_type | Msg_text |
     +---------+--------------------+----------+----------+
     | test.t1 | assign_to_keycache | status   | OK       |
     | test.t2 | assign_to_keycache | status   | OK       |
     | test.t3 | assign_to_keycache | status   | OK       |
     +---------+--------------------+----------+----------+

The key cache referred to in a *Note `CACHE INDEX': cache-index.
statement can be created by setting its size with a *Note `SET GLOBAL':
set-option. parameter setting statement or by using server startup
options. For example:

     mysql> SET GLOBAL keycache1.key_buffer_size=128*1024;

To destroy a key cache, set its size to zero:

     mysql> SET GLOBAL keycache1.key_buffer_size=0;

Note that you cannot destroy the default key cache. Any attempt to do
this will be ignored:

     mysql> SET GLOBAL key_buffer_size = 0;

     mysql> SHOW VARIABLES LIKE 'key_buffer_size';
     +-----------------+---------+
     | Variable_name   | Value   |
     +-----------------+---------+
     | key_buffer_size | 8384512 |
     +-----------------+---------+

Key cache variables are structured system variables that have a name
and components. For `keycache1.key_buffer_size', `keycache1' is the
cache variable name and `key_buffer_size' is the cache component. See
*Note structured-system-variables::, for a description of the syntax
used for referring to structured key cache system variables.

By default, table indexes are assigned to the main (default) key cache
created at the server startup. When a key cache is destroyed, all
indexes assigned to it are reassigned to the default key cache.

For a busy server, we recommend a strategy that uses three key caches:

   * A `hot' key cache that takes up 20% of the space allocated for all
     key caches. Use this for tables that are heavily used for searches
     but that are not updated.

   * A `cold' key cache that takes up 20% of the space allocated for
     all key caches. Use this cache for medium-sized, intensively
     modified tables, such as temporary tables.

   * A `warm' key cache that takes up 60% of the key cache space.
     Employ this as the default key cache, to be used by default for
     all other tables.

One reason the use of three key caches is beneficial is that access to
one key cache structure does not block access to the others. Statements
that access tables assigned to one cache do not compete with statements
that access tables assigned to another cache. Performance gains occur
for other reasons as well:

   * The hot cache is used only for retrieval queries, so its contents
     are never modified. Consequently, whenever an index block needs to
     be pulled in from disk, the contents of the cache block chosen for
     replacement need not be flushed first.

   * For an index assigned to the hot cache, if there are no queries
     requiring an index scan, there is a high probability that the
     index blocks corresponding to non-leaf nodes of the index B-tree
     remain in the cache.

   * An update operation most frequently executed for temporary tables
     is performed much faster when the updated node is in the cache and
     need not be read in from disk first. If the size of the indexes of
     the temporary tables are comparable with the size of cold key
     cache, the probability is very high that the updated node is in the
     cache.

*Note `CACHE INDEX': cache-index. sets up an association between a
table and a key cache, but the association is lost each time the server
restarts. If you want the association to take effect each time the
server starts, one way to accomplish this is to use an option file:
Include variable settings that configure your key caches, and an
`init-file' option that names a file containing *Note `CACHE INDEX':
cache-index.  statements to be executed. For example:

     key_buffer_size = 4G
     hot_cache.key_buffer_size = 2G
     cold_cache.key_buffer_size = 2G
     init_file=/PATH/TO/DATA-DIRECTORY/mysqld_init.sql

MySQL Enterprise

For advice on how best to configure your `my.cnf/my.ini ' option file
subscribe to MySQL Enterprise Monitor. Recommendations are based on
actual table usage. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The statements in `mysqld_init.sql' are executed each time the server
starts. The file should contain one SQL statement per line. The
following example assigns several tables each to `hot_cache' and
`cold_cache':

     CACHE INDEX db1.t1, db1.t2, db2.t3 IN hot_cache
     CACHE INDEX db1.t4, db2.t5, db2.t6 IN cold_cache


File: manual.info,  Node: midpoint-insertion,  Next: index-preloading,  Prev: multiple-key-caches,  Up: myisam-key-cache

7.4.6.3 Midpoint Insertion Strategy
...................................

By default, the key cache management system uses the LRU strategy for
choosing key cache blocks to be evicted, but it also supports a more
sophisticated method called the _midpoint insertion strategy._

When using the midpoint insertion strategy, the LRU chain is divided
into two parts: a hot sub-chain and a warm sub-chain.  The division
point between two parts is not fixed, but the key cache management
system takes care that the warm part is not `too short,' always
containing at least `key_cache_division_limit' percent of the key cache
blocks.  `key_cache_division_limit' is a component of structured key
cache variables, so its value is a parameter that can be set per cache.

When an index block is read from a table into the key cache, it is
placed at the end of the warm sub-chain. After a certain number of hits
(accesses of the block), it is promoted to the hot sub-chain. At
present, the number of hits required to promote a block (3) is the same
for all index blocks.

A block promoted into the hot sub-chain is placed at the end of the
chain. The block then circulates within this sub-chain.  If the block
stays at the beginning of the sub-chain for a long enough time, it is
demoted to the warm chain. This time is determined by the value of the
`key_cache_age_threshold' component of the key cache.

The threshold value prescribes that, for a key cache containing N
blocks, the block at the beginning of the hot sub-chain not accessed
within the last `N x key_cache_age_threshold / 100' hits is to be moved
to the beginning of the warm sub-chain. It then becomes the first
candidate for eviction, because blocks for replacement always are taken
from the beginning of the warm sub-chain.

The midpoint insertion strategy allows you to keep more-valued blocks
always in the cache. If you prefer to use the plain LRU strategy, leave
the `key_cache_division_limit' value set to its default of 100.

The midpoint insertion strategy helps to improve performance when
execution of a query that requires an index scan effectively pushes out
of the cache all the index blocks corresponding to valuable high-level
B-tree nodes. To avoid this, you must use a midpoint insertion strategy
with the `key_cache_division_limit' set to much less than 100. Then
valuable frequently hit nodes are preserved in the hot sub-chain during
an index scan operation as well.


File: manual.info,  Node: index-preloading,  Next: key-cache-block-size,  Prev: midpoint-insertion,  Up: myisam-key-cache

7.4.6.4 Index Preloading
........................

If there are enough blocks in a key cache to hold blocks of an entire
index, or at least the blocks corresponding to its non-leaf nodes, it
makes sense to preload the key cache with index blocks before starting
to use it. Preloading allows you to put the table index blocks into a
key cache buffer in the most efficient way: by reading the index blocks
from disk sequentially.

Without preloading, the blocks are still placed into the key cache as
needed by queries. Although the blocks will stay in the cache, because
there are enough buffers for all of them, they are fetched from disk in
random order, and not sequentially.

To preload an index into a cache, use the *Note `LOAD INDEX INTO
CACHE': load-index. statement. For example, the following statement
preloads nodes (index blocks) of indexes of the tables `t1' and `t2':

     mysql> LOAD INDEX INTO CACHE t1, t2 IGNORE LEAVES;
     +---------+--------------+----------+----------+
     | Table   | Op           | Msg_type | Msg_text |
     +---------+--------------+----------+----------+
     | test.t1 | preload_keys | status   | OK       |
     | test.t2 | preload_keys | status   | OK       |
     +---------+--------------+----------+----------+

The `IGNORE LEAVES' modifier causes only blocks for the non-leaf nodes
of the index to be preloaded.  Thus, the statement shown preloads all
index blocks from `t1', but only blocks for the non-leaf nodes from
`t2'.

If an index has been assigned to a key cache using a *Note `CACHE
INDEX': cache-index. statement, preloading places index blocks into
that cache. Otherwise, the index is loaded into the default key cache.


File: manual.info,  Node: key-cache-block-size,  Next: key-cache-restructuring,  Prev: index-preloading,  Up: myisam-key-cache

7.4.6.5 Key Cache Block Size
............................

It is possible to specify the size of the block buffers for an
individual key cache using the `key_cache_block_size' variable. This
permits tuning of the performance of I/O operations for index files.

The best performance for I/O operations is achieved when the size of
read buffers is equal to the size of the native operating system I/O
buffers. But setting the size of key nodes equal to the size of the I/O
buffer does not always ensure the best overall performance. When
reading the big leaf nodes, the server pulls in a lot of unnecessary
data, effectively preventing reading other leaf nodes.

To control the size of blocks in the `.MYI' index file of `MyISAM'
tables, use the `--myisam-block-size' option at server startup.


File: manual.info,  Node: key-cache-restructuring,  Prev: key-cache-block-size,  Up: myisam-key-cache

7.4.6.6 Restructuring a Key Cache
.................................

A key cache can be restructured at any time by updating its parameter
values. For example:

     mysql> SET GLOBAL cold_cache.key_buffer_size=4*1024*1024;

If you assign to either the `key_buffer_size' or `key_cache_block_size'
key cache component a value that differs from the component's current
value, the server destroys the cache's old structure and creates a new
one based on the new values. If the cache contains any dirty blocks,
the server saves them to disk before destroying and re-creating the
cache. Restructuring does not occur if you change other key cache
parameters.

When restructuring a key cache, the server first flushes the contents
of any dirty buffers to disk. After that, the cache contents become
unavailable. However, restructuring does not block queries that need to
use indexes assigned to the cache.  Instead, the server directly
accesses the table indexes using native file system caching. File
system caching is not as efficient as using a key cache, so although
queries execute, a slowdown can be anticipated. After the cache has been
restructured, it becomes available again for caching indexes assigned
to it, and the use of file system caching for the indexes ceases.


File: manual.info,  Node: myisam-index-statistics,  Next: table-cache,  Prev: myisam-key-cache,  Up: optimizing-database-structure

7.4.7 `MyISAM' Index Statistics Collection
------------------------------------------

Storage engines collect statistics about tables for use by the
optimizer. Table statistics are based on value groups, where a value
group is a set of rows with the same key prefix value. For optimizer
purposes, an important statistic is the average value group size.

MySQL uses the average value group size in the following ways:

   * To estimate how may rows must be read for each `ref' access

   * To estimate how many row a partial join will produce; that is, the
     number of rows that an operation of this form will produce:

          (...) JOIN TBL_NAME ON TBL_NAME.KEY = EXPR

As the average value group size for an index increases, the index is
less useful for those two purposes because the average number of rows
per lookup increases: For the index to be good for optimization
purposes, it is best that each index value target a small number of
rows in the table. When a given index value yields a large number of
rows, the index is less useful and MySQL is less likely to use it.

The average value group size is related to table cardinality, which is
the number of value groups. The *Note `SHOW INDEX': show-index.
statement displays a cardinality value based on N/S, where N is the
number of rows in the table and S is the average value group size. That
ratio yields an approximate number of value groups in the table.

For a join based on the `<=>' comparison operator, `NULL' is not
treated differently from any other value: `NULL <=> NULL', just as `N
<=> N' for any other N.

However, for a join based on the `=' operator, `NULL' is different from
non-`NULL' values: `EXPR1 = EXPR2' is not true when EXPR1 or EXPR2 (or
both) are `NULL'. This affects `ref' accesses for comparisons of the
form `TBL_NAME.KEY = EXPR': MySQL will not access the table if the
current value of EXPR is `NULL', because the comparison cannot be true.

For `=' comparisons, it does not matter how many `NULL' values are in
the table. For optimization purposes, the relevant value is the average
size of the non-`NULL' value groups. However, MySQL does not currently
allow that average size to be collected or used.

For `MyISAM' tables, you have some control over collection of table
statistics by means of the `myisam_stats_method' system variable. This
variable has three possible values, which differ as follows:

   * When `myisam_stats_method' is `nulls_equal', all `NULL' values are
     treated as identical (that is, they all form a single value group).

     If the `NULL' value group size is much higher than the average
     non-`NULL' value group size, this method skews the average value
     group size upward. This makes index appear to the optimizer to be
     less useful than it really is for joins that look for non-`NULL'
     values. Consequently, the `nulls_equal' method may cause the
     optimizer not to use the index for `ref' accesses when it should.

   * When `myisam_stats_method' is `nulls_unequal', `NULL' values are
     not considered the same. Instead, each `NULL' value forms a
     separate value group of size 1.

     If you have many `NULL' values, this method skews the average
     value group size downward. If the average non-`NULL' value group
     size is large, counting `NULL' values each as a group of size 1
     causes the optimizer to overestimate the value of the index for
     joins that look for non-`NULL' values. Consequently, the
     `nulls_unequal' method may cause the optimizer to use this index
     for `ref' lookups when other methods may be better.

   * When `myisam_stats_method' is `nulls_ignored', `NULL' values are
     ignored.

If you tend to use many joins that use `<=>' rather than `=', `NULL'
values are not special in comparisons and one `NULL' is equal to
another. In this case, `nulls_equal' is the appropriate statistics
method.

The `myisam_stats_method' system variable has global and session
values. Setting the global value affects `MyISAM' statistics collection
for all `MyISAM' tables. Setting the session value affects statistics
collection only for the current client connection. This means that you
can force a table's statistics to be regenerated with a given method
without affecting other clients by setting the session value of
`myisam_stats_method'.

To regenerate table statistics, you can use any of the following
methods:

   * Execute *Note `myisamchk --stats_method=METHOD_NAME --analyze':
     myisamchk.

   * Change the table to cause its statistics to go out of date (for
     example, insert a row and then delete it), and then set
     `myisam_stats_method' and issue an *Note `ANALYZE TABLE':
     analyze-table.  statement

Some caveats regarding the use of `myisam_stats_method':

   * You can force table statistics to be collected explicitly, as just
     described. However, MySQL may also collect statistics
     automatically. For example, if during the course of executing
     statements for a table, some of those statements modify the table,
     MySQL may collect statistics.  (This may occur for bulk inserts or
     deletes, or some *Note `ALTER TABLE': alter-table. statements, for
     example.) If this happens, the statistics are collected using
     whatever value `myisam_stats_method' has at the time. Thus, if you
     collect statistics using one method, but `myisam_stats_method' is
     set to the other method when a table's statistics are collected
     automatically later, the other method will be used.

   * There is no way to tell which method was used to generate
     statistics for a given `MyISAM' table.

   * `myisam_stats_method' applies only to `MyISAM' tables. Other
     storage engines have only one method for collecting table
     statistics. Usually it is closer to the `nulls_equal' method.


File: manual.info,  Node: table-cache,  Next: creating-many-tables,  Prev: myisam-index-statistics,  Up: optimizing-database-structure

7.4.8 How MySQL Opens and Closes Tables
---------------------------------------

When you execute a *Note `mysqladmin status': mysqladmin. command, you
should see something like this:

     Uptime: 426 Running threads: 1 Questions: 11082
     Reloads: 1 Open tables: 12

The `Open tables' value of 12 can be somewhat puzzling if you have only
six tables.

MySQL is multi-threaded, so there may be many clients issuing queries
for a given table simultaneously. To minimize the problem with multiple
client threads having different states on the same table, the table is
opened independently by each concurrent thread. This uses additional
memory but normally increases performance. With `MyISAM' tables, one
extra file descriptor is required for the data file for each client
that has the table open. (By contrast, the index file descriptor is
shared between all threads.)

The `table_open_cache', `max_connections', and `max_tmp_tables' system
variables affect the maximum number of files the server keeps open. If
you increase one or more of these values, you may run up against a
limit imposed by your operating system on the per-process number of
open file descriptors. Many operating systems allow you to increase the
open-files limit, although the method varies widely from system to
system. Consult your operating system documentation to determine
whether it is possible to increase the limit and how to do so.

`table_open_cache' is related to `max_connections'. For example, for
200 concurrent running connections, you should have a table cache size
of at least `200 x N', where N is the maximum number of tables per join
in any of the queries which you execute. You must also reserve some
extra file descriptors for temporary tables and files.

Make sure that your operating system can handle the number of open file
descriptors implied by the `table_open_cache' setting. If
`table_open_cache' is set too high, MySQL may run out of file
descriptors and refuse connections, fail to perform queries, and be
very unreliable.  You also have to take into account that the `MyISAM'
storage engine needs two file descriptors for each unique open table.
You can increase the number of file descriptors available to MySQL
using the `--open-files-limit' startup option to *Note `mysqld':
mysqld. See *Note not-enough-file-handles::.

The cache of open tables is kept at a level of `table_open_cache'
entries. The default value is 64; this can be changed with the
`--table_open_cache' option to *Note `mysqld': mysqld. Note that MySQL
may temporarily open more tables than this to execute queries.

MySQL Enterprise

Performance may suffer if `table_open_cache' is set too low. For expert
advice on the optimum value for this variable, subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

MySQL closes an unused table and removes it from the table cache under
the following circumstances:

   * When the cache is full and a thread tries to open a table that is
     not in the cache.

   * When the cache contains more than `table_open_cache' entries and a
     table in the cache is no longer being used by any threads.

   * When a table flushing operation occurs. This happens when someone
     issues a *Note `FLUSH TABLES': flush. statement or executes a
     *Note `mysqladmin flush-tables': mysqladmin. or *Note `mysqladmin
     refresh': mysqladmin. command.

When the table cache fills up, the server uses the following procedure
to locate a cache entry to use:

   * Tables that are not currently in use are released, beginning with
     the table least recently used.

   * If a new table needs to be opened, but the cache is full and no
     tables can be released, the cache is temporarily extended as
     necessary. When the cache is in a temporarily extended state and a
     table goes from a used to unused state, the table is closed and
     released from the cache.

A `MyISAM' table is opened for each concurrent access. This means the
table needs to be opened twice if two threads access the same table or
if a thread accesses the table twice in the same query (for example, by
joining the table to itself). Each concurrent open requires an entry in
the table cache. The first open of any `MyISAM' table takes two file
descriptors: one for the data file and one for the index file. Each
additional use of the table takes only one file descriptor for the data
file. The index file descriptor is shared among all threads.

If you are opening a table with the `HANDLER TBL_NAME OPEN' statement, a
dedicated table object is allocated for the thread. This table object
is not shared by other threads and is not closed until the thread calls
`HANDLER TBL_NAME CLOSE' or the thread terminates. When this happens,
the table is put back in the table cache (if the cache is not full). See
*Note handler::.

You can determine whether your table cache is too small by checking the
*Note `mysqld': mysqld. status variable `Opened_tables', which indicates
the number of table-opening operations since the server started:

     mysql> SHOW GLOBAL STATUS LIKE 'Opened_tables';
     +---------------+-------+
     | Variable_name | Value |
     +---------------+-------+
     | Opened_tables | 2741  |
     +---------------+-------+

If the value is very large or increases rapidly, even when you have not
issued many *Note `FLUSH TABLES': flush.  statements, you should
increase the table cache size. See *Note server-system-variables::, and
*Note server-status-variables::.


File: manual.info,  Node: creating-many-tables,  Prev: table-cache,  Up: optimizing-database-structure

7.4.9 Disadvantages of Creating Many Tables in the Same Database
----------------------------------------------------------------

If you have many `MyISAM' tables in the same database directory, open,
close, and create operations are slow.  If you execute *Note `SELECT':
select. statements on many different tables, there is a little overhead
when the table cache is full, because for every table that has to be
opened, another must be closed. You can reduce this overhead by
increasing the number of entries allowed in the table cache.


File: manual.info,  Node: optimizing-the-server,  Next: disk-issues,  Prev: optimizing-database-structure,  Up: optimization

7.5 Optimizing the MySQL Server
===============================

* Menu:

* compile-and-link-options::     How Compiling and Linking Affects the Speed of MySQL
* system-optimization::          System Factors and Startup Parameter Tuning
* server-parameters::            Tuning Server Parameters
* controlling-optimizer::        Controlling Query Optimizer Performance
* query-cache::                  The MySQL Query Cache
* thread-information::           Examining Thread Information
* connection-threads::           How MySQL Uses Threads for Client Connections
* memory-use::                   How MySQL Uses Memory
* large-page-support::           Enabling Large Page Support
* internal-temporary-tables::    How MySQL Uses Internal Temporary Tables
* dns::                          How MySQL Uses DNS


File: manual.info,  Node: compile-and-link-options,  Next: system-optimization,  Prev: optimizing-the-server,  Up: optimizing-the-server

7.5.1 How Compiling and Linking Affects the Speed of MySQL
----------------------------------------------------------

Most of the following tests were performed on Linux with the MySQL
benchmarks, but they should give some indication for other operating
systems and workloads.

You obtain the fastest executables when you link with `-static'.

On Linux, it is best to compile the server with `pgcc' and `-O3'. You
need about 200MB memory to compile `sql_yacc.cc' with these options,
because `gcc' or `pgcc' needs a great deal of memory to make all
functions inline. You should also set `CXX=gcc' when configuring MySQL
to avoid inclusion of the `libstdc++' library, which is not needed. Note
that with some versions of `pgcc', the resulting binary runs only on
true Pentium processors, even if you use the compiler option indicating
that you want the resulting code to work on all x586-type processors
(such as AMD).

By using a better compiler and compilation options, you can obtain a
10-30% speed increase in applications. This is particularly important
if you compile the MySQL server yourself.

When we tested both the Cygnus CodeFusion and Fujitsu compilers,
neither was sufficiently bug-free to allow MySQL to be compiled with
optimizations enabled.

The standard MySQL binary distributions are compiled with support for
all character sets. When you compile MySQL yourself, you should include
support only for the character sets that you are going to use. This is
controlled by the `--with-charset' option to `configure'.

Here is a list of some measurements that we have made:

   * If you use `pgcc' and compile everything with `-O6', the *Note
     `mysqld': mysqld.  server is 1% faster than with `gcc' 2.95.2.

   * If you link dynamically (without `-static'), the result is 13%
     slower on Linux. Note that you still can use a dynamically linked
     MySQL library for your client applications. It is the server that
     is most critical for performance.

   * For a connection from a client to a server running on the same
     host, if you connect using TCP/IP rather than a Unix socket file,
     performance is 7.5% slower. (On Unix, if you connect to the host
     name `localhost', MySQL uses a socket file by default.)

   * For TCP/IP connections from a client to a server, connecting to a
     remote server on another host is 8-11% slower than connecting to a
     server on the same host, even for connections faster than 100Mb/s
     Ethernet.

   * When running our benchmark tests using secure connections (all
     data encrypted with internal SSL support) performance was 55%
     slower than with unencrypted connections.

   * If you compile with `--with-debug=full', most queries are 20%
     slower. Some queries may take substantially longer; for example,
     the MySQL benchmarks run 35% slower. If you use `--with-debug'
     (without `=full'), the speed decrease is only 15%. For a version
     of *Note `mysqld': mysqld. that has been compiled with
     `--with-debug=full', you can disable memory checking at runtime by
     starting it with the `--skip-safemalloc' option. The execution
     speed should then be close to that obtained when configuring with
     `--with-debug'.

   * On a Sun UltraSPARC-IIe, a server compiled with Forte 5.0 is 4%
     faster than one compiled with `gcc' 3.2.

   * On a Sun UltraSPARC-IIe, a server compiled with Forte 5.0 is 4%
     faster in 32-bit mode than in 64-bit mode.

   * Compiling with `gcc' 2.95.2 for UltraSPARC with the `-mcpu=v8
     -Wa,-xarch=v8plusa' options gives 4% more performance.

   * On Solaris 2.5.1, MIT-pthreads is 8-12% slower than Solaris native
     threads on a single processor. With greater loads or more CPUs,
     the difference should be larger.

   * Compiling on Linux-x86 using `gcc' without frame pointers
     (`-fomit-frame-pointer' or `-fomit-frame-pointer -ffixed-ebp')
     makes *Note `mysqld': mysqld. 1-4% faster.

Binary MySQL distributions for Linux that are provided by MySQL AB used
to be compiled with `pgcc'. We had to go back to regular `gcc' due to a
bug in `pgcc' that would generate binaries that do not run on AMD. We
will continue using `gcc' until that bug is resolved. In the meantime,
if you have a non-AMD machine, you can build a faster binary by
compiling with `pgcc'. The standard MySQL Linux binary is linked
statically to make it faster and more portable.


File: manual.info,  Node: system-optimization,  Next: server-parameters,  Prev: compile-and-link-options,  Up: optimizing-the-server

7.5.2 System Factors and Startup Parameter Tuning
-------------------------------------------------

We start with system-level factors, because some of these decisions
must be made very early to achieve large performance gains. In other
cases, a quick look at this section may suffice.  However, it is always
nice to have a sense of how much can be gained by changing factors that
apply at this level.

The operating system to use is very important. To get the best use of
multiple-CPU machines, you should use Solaris (because its threads
implementation works well) or Linux (because the 2.4 and later kernels
have good SMP support). Note that older Linux kernels have a 2GB
filesize limit by default. If you have such a kernel and a need for
files larger than 2GB, you should get the Large File Support (LFS)
patch for the ext2 file system. Other file systems such as ReiserFS and
XFS do not have this 2GB limitation.

Before using MySQL in production, we advise you to test it on your
intended platform.

Other tips:

   * If you have enough RAM, you could remove all swap devices.  Some
     operating systems use a swap device in some contexts even if you
     have free memory.

   * Avoid external locking. Since MySQL 4.0, the default has been for
     external locking to be disabled on all systems. The
     `--external-locking' and `--skip-external-locking' options
     explicitly enable and disable external locking.

     Note that disabling external locking does not affect MySQL's
     functionality as long as you run only one server. Just remember to
     take down the server (or lock and flush the relevant tables)
     before you run *Note `myisamchk': myisamchk. On some systems it is
     mandatory to disable external locking because it does not work,
     anyway.

     The only case in which you cannot disable external locking is when
     you run multiple MySQL _servers_ (not clients) on the same data,
     or if you run *Note `myisamchk': myisamchk. to check (not repair)
     a table without telling the server to flush and lock the tables
     first. Note that using multiple MySQL servers to access the same
     data concurrently is generally _not_ recommended, except when
     using MySQL Cluster.

     *Note*:

     MySQL Cluster is currently not supported in MySQL 6.0.  Users
     wishing to upgrade a MySQL Cluster from MySQL 5.0 or 5.1 should
     instead migrate to MySQL Cluster NDB 6.2 or 6.3; these are based
     on MySQL 5.1 but contain the latest improvements and fixes for
     `NDBCLUSTER'.

     The *Note `LOCK TABLES': lock-tables. and *Note `UNLOCK TABLES':
     lock-tables. statements use internal locking, so you can use them
     even if external locking is disabled.


File: manual.info,  Node: server-parameters,  Next: controlling-optimizer,  Prev: system-optimization,  Up: optimizing-the-server

7.5.3 Tuning Server Parameters
------------------------------

You can determine the default buffer sizes used by the *Note `mysqld':
mysqld. server using this command:

     shell> mysqld --verbose --help

This command produces a list of all *Note `mysqld': mysqld.  options
and configurable system variables. The output includes the default
variable values and looks something like this:

     abort-slave-event-count           0
     allow-suspicious-udfs             FALSE
     archive                           TRUE
     auto-increment-increment          1
     auto-increment-offset             1
     automatic-sp-privileges           TRUE
     backup-history-log                TRUE
     backup-progress-log               TRUE
     backupdir                         /home/jon/bin/mysql-6.0/var/
     back_log                          50
     basedir                           /home/jon/bin/mysql-6.0/
     bind-address                      (No default value)
     binlog-row-event-max-size         1024
     binlog_cache_size                 32768
     binlog_format                     (No default value)
     bulk_insert_buffer_size           8388608
     character-set-client-handshake    TRUE
     character-set-filesystem          binary
     character-set-server              latin1
     character-sets-dir                /home/jon/bin/mysql-6.0/share/mysql/charsets/
     chroot                            (No default value)
     collation-server                  latin1_swedish_ci
     completion-type                   0
     concurrent-insert                 1
     connect_timeout                   10
     console                           FALSE
     datadir                           .
     datetime_format                   %Y-%m-%d %H:%i:%s
     date_format                       %Y-%m-%d
     default-character-set             latin1
     default-collation                 latin1_swedish_ci
     default-storage-engine            MyISAM
     default-table-type                MyISAM
     default-time-zone                 (No default value)
     default_week_format               0
     delayed_insert_limit              100
     delayed_insert_timeout            300
     delayed_queue_size                1000
     des-key-file                      (No default value)
     disconnect-slave-event-count      0
     div_precision_increment           4
     enable-locking                    FALSE
     engine-condition-pushdown         TRUE
     expire_logs_days                  0
     external-locking                  FALSE
     falcon                            TRUE
     falcon-checkpoint-schedule        7 * * * * *
     falcon-checksums                  TRUE
     falcon-consistent-read            TRUE
     falcon-debug-mask                 0
     falcon-debug-server               FALSE
     falcon-debug-trace                0
     falcon-direct-io                  1
     falcon-gopher-threads             5
     falcon-index-chill-threshold      4194304
     falcon-io-threads                 2
     falcon-large-blob-threshold       160000
     falcon-lock-wait-timeout          50
     falcon-page-cache-size            4194304
     falcon-page-size                  4096
     falcon-record-chill-threshold     5242880
     falcon-record-memory-max          262144000
     falcon-record-scavenge-floor      50
     falcon-record-scavenge-threshold  67
     falcon-scavenge-schedule          15,45 * * * * *
     falcon-serial-log-block-size      0
     falcon-serial-log-buffers         20
     falcon-serial-log-dir             /home/jon/bin/mysql-6.0/var/
     falcon-serial-log-file-size       10485760
     falcon-serial-log-priority        1
     falcon-support-xa                 FALSE
     falcon-use-deferred-index-hash    FALSE
     falcon-use-sectorcache            FALSE
     falcon-use-supernodes             TRUE
     flush_time                        0
     ft_max_word_len                   84
     ft_min_word_len                   4
     ft_query_expansion_limit          20
     ft_stopword_file                  (No default value)
     gdb                               FALSE
     general-log                       FALSE
     group_concat_max_len              1024
     help                              TRUE
     init-connect                      (No default value)
     init-file                         (No default value)
     init-slave                        (No default value)
     innodb                            TRUE
     innodb-adaptive-hash-index        TRUE
     innodb-additional-mem-pool-size   1048576
     innodb-autoextend-increment       8
     innodb-autoinc-lock-mode          1
     innodb-buffer-pool-size           8388608
     innodb-checksums                  TRUE
     innodb-commit-concurrency         0
     innodb-concurrency-tickets        500
     innodb-data-file-path             (No default value)
     innodb-data-home-dir              (No default value)
     innodb-doublewrite                TRUE
     innodb-fast-shutdown              1
     innodb-file-io-threads            4
     innodb-file-per-table             FALSE
     innodb-flush-log-at-trx-commit    1
     innodb-flush-method               (No default value)
     innodb-force-recovery             0
     innodb-lock-wait-timeout          50
     innodb-locks-unsafe-for-binlog    FALSE
     innodb-log-buffer-size            1048576
     innodb-log-file-size              5242880
     innodb-log-files-in-group         2
     innodb-log-group-home-dir         (No default value)
     innodb-max-dirty-pages-pct        90
     innodb-max-purge-lag              0
     innodb-mirrored-log-groups        1
     innodb-open-files                 300
     innodb-rollback-on-timeout        FALSE
     innodb-stats-on-metadata          TRUE
     innodb-status-file                FALSE
     innodb-support-xa                 TRUE
     innodb-sync-spin-loops            20
     innodb-table-locks                TRUE
     innodb-thread-concurrency         8
     innodb-thread-sleep-delay         10000
     interactive_timeout               28800
     join_buffer_size                  131072
     keep_files_on_create              FALSE
     key_buffer_size                   8388600
     key_cache_age_threshold           300
     key_cache_block_size              1024
     key_cache_division_limit          100
     language                          /home/jon/bin/mysql-6.0/share/mysql/english/
     large-pages                       FALSE
     lc-time-names                     en_US
     local-infile                      TRUE
     log                               (No default value)
     log-backup-output                 TABLE
     log-bin                           (No default value)
     log-bin-index                     (No default value)
     log-bin-trust-function-creators   FALSE
     log-bin-trust-routine-creators    FALSE
     log-error
     log-isam                          myisam.log
     log-output                        FILE
     log-queries-not-using-indexes     FALSE
     log-short-format                  FALSE
     log-slave-updates                 FALSE
     log-slow-admin-statements         FALSE
     log-slow-queries                  (No default value)
     log-slow-slave-statements         FALSE
     log-tc                            tc.log
     log-tc-size                       24576
     log-update                        (No default value)
     log-warnings                      1
     long_query_time                   10
     low-priority-updates              FALSE
     lower_case_table_names            0
     maria                             TRUE
     maria-block-size                  8192
     maria-checkpoint-interval         30
     maria-force-start-after-recovery-failures 0
     maria-log-dir-path                /home/jon/bin/mysql-6.0/var/
     maria-log-file-size               1073741824
     maria-log-purge-type              immediate
     maria-max-sort-file-size          9223372036854775807
     maria-page-checksum               TRUE
     maria-pagecache-age-threshold     300
     maria-pagecache-buffer-size       8388600
     maria-pagecache-division-limit    100
     maria-recover                     OFF
     maria-repair-threads              1
     maria-sort-buffer-size            8388608
     maria-stats-method                nulls_unequal
     maria-sync-log-dir                NEWFILE
     master-info-file                  master.info
     master-retry-count                86400
     max-binlog-dump-events            0
     max_allowed_packet                1048576
     max_binlog_cache_size             18446744073709551615
     max_binlog_size                   1073741824
     max_connections                   151
     max_connect_errors                10
     max_delayed_threads               20
     max_error_count                   64
     max_heap_table_size               16777216
     max_join_size                     18446744073709551615
     max_length_for_sort_data          1024
     max_prepared_stmt_count           16382
     max_relay_log_size                0
     max_seeks_for_key                 18446744073709551615
     max_sort_length                   1024
     max_sp_recursion_depth            0
     max_tmp_tables                    32
     max_user_connections              0
     max_write_lock_count              18446744073709551615
     memlock                           FALSE
     min_examined_row_limit            0
     myisam-recover                    OFF
     myisam_block_size                 1024
     myisam_data_pointer_size          6
     myisam_max_sort_file_size         9223372036854775807
     myisam_repair_threads             1
     myisam_sort_buffer_size           8388608
     myisam_stats_method               nulls_unequal
     myisam_use_mmap                   FALSE
     net_buffer_length                 16384
     net_read_timeout                  30
     net_retry_count                   10
     net_write_timeout                 60
     new                               FALSE
     old                               FALSE
     old-alter-table                   FALSE
     old-passwords                     FALSE
     old-style-user-limits             FALSE
     open_files_limit                  1024
     optimizer_prune_level             1
     optimizer_search_depth            62
     pid-file                          /home/jon/bin/mysql-6.0/var/tonfisk.pid
     plugin_dir                        /home/jon/bin/mysql-6.0/lib/mysql/plugin
     plugin_load                       (No default value)
     port                              3306
     port-open-timeout                 0
     preload_buffer_size               32768
     profiling_history_size            15
     query_alloc_block_size            8192
     query_cache_limit                 1048576
     query_cache_min_res_unit          4096
     query_cache_size                  0
     query_cache_type                  1
     query_cache_wlock_invalidate      FALSE
     query_prealloc_size               8192
     range_alloc_block_size            4096
     read_buffer_size                  131072
     read_only                         FALSE
     read_rnd_buffer_size              262144
     record_buffer                     131072
     relay-log                         (No default value)
     relay-log-index                   (No default value)
     relay-log-info-file               relay-log.info
     relay_log_purge                   TRUE
     relay_log_space_limit             0
     replicate-same-server-id          FALSE
     report-host                       (No default value)
     report-password                   (No default value)
     report-port                       3306
     report-user                       (No default value)
     rpl-recovery-rank                 0
     safe-user-create                  FALSE
     secure-auth                       FALSE
     secure-backup-file-priv           (No default value)
     secure-file-priv                  (No default value)
     server-id                         0
     show-slave-auth-info              FALSE
     skip-grant-tables                 FALSE
     skip-slave-start                  FALSE
     slave-allow-batching              FALSE
     slave-exec-mode                   STRICT
     slave-load-tmpdir                 /tmp
     slave_compressed_protocol         FALSE
     slave_net_timeout                 3600
     slave_transaction_retries         10
     slow-query-log                    FALSE
     slow_launch_time                  2
     socket                            /tmp/mysql.sock
     sort_buffer_size                  2097144
     sporadic-binlog-dump-fail         FALSE
     sql-mode                          OFF
     ssl                               FALSE
     ssl-ca                            (No default value)
     ssl-capath                        (No default value)
     ssl-cert                          (No default value)
     ssl-cipher                        (No default value)
     ssl-key                           (No default value)
     symbolic-links                    TRUE
     sync-binlog                       0
     sync-frm                          TRUE
     sysdate-is-now                    FALSE
     table_cache                       64
     table_definition_cache            256
     table_lock_wait_timeout           50
     table_open_cache                  64
     tc-heuristic-recover              (No default value)
     temp-pool                         TRUE
     thread_cache_size                 0
     thread_concurrency                10
     thread_stack                      262144
     timed_mutexes                     FALSE
     time_format                       %H:%i:%s
     tmpdir                            (No default value)
     tmp_table_size                    16777216
     transaction_alloc_block_size      8192
     transaction_prealloc_size         4096
     updatable_views_with_limit        1
     use-symbolic-links                TRUE
     verbose                           TRUE
     wait_timeout                      28800
     warnings                          1

For a *Note `mysqld': mysqld. server that is currently running, you can
see the current values of its system variables by connecting to it and
issuing this statement:

     mysql> SHOW VARIABLES;

You can also see some statistical and status indicators for a running
server by issuing this statement:

     mysql> SHOW STATUS;

System variable and status information also can be obtained using *Note
`mysqladmin': mysqladmin.:

     shell> mysqladmin variables
     shell> mysqladmin extended-status

For a full description of all system and status variables, see *Note
server-system-variables::, and *Note server-status-variables::.

MySQL uses algorithms that are very scalable, so you can usually run
with very little memory. However, normally you get better performance
by giving MySQL more memory.

When tuning a MySQL server, the two most important variables to
configure are `key_buffer_size' and `table_open_cache'. You should
first feel confident that you have these set appropriately before
trying to change any other variables.

The following examples indicate some typical variable values for
different runtime configurations.

   * If you have at least 256MB of memory and many tables and want
     maximum performance with a moderate number of clients, you should
     use something like this:

          shell> mysqld_safe --key_buffer_size=64M --table_open_cache=256 \
                     --sort_buffer_size=4M --read_buffer_size=1M &

   * If you have only 128MB of memory and only a few tables, but you
     still do a lot of sorting, you can use something like this:

          shell> mysqld_safe --key_buffer_size=16M --sort_buffer_size=1M

     If there are very many simultaneous connections, swapping problems
     may occur unless *Note `mysqld': mysqld. has been configured to
     use very little memory for each connection.  *Note `mysqld':
     mysqld. performs better if you have enough memory for all
     connections.

   * With little memory and lots of connections, use something like
     this:

          shell> mysqld_safe --key_buffer_size=512K --sort_buffer_size=100K \
                     --read_buffer_size=100K &

     Or even this:

          shell> mysqld_safe --key_buffer_size=512K --sort_buffer_size=16K \
                     --table_open_cache=32 --read_buffer_size=8K \
                     --net_buffer_length=1K &

If you are performing `GROUP BY' or `ORDER BY' operations on tables
that are much larger than your available memory, you should increase
the value of `read_rnd_buffer_size' to speed up the reading of rows
following sorting operations.

You can make use of the example option files included with your MySQL
distribution; see *Note option-files-preconfigured::.

If you specify an option on the command line for *Note `mysqld':
mysqld. or *Note `mysqld_safe': mysqld-safe, it remains in effect only
for that invocation of the server. To use the option every time the
server runs, put it in an option file.

To see the effects of a parameter change, do something like this:

     shell> mysqld --key_buffer_size=32M --verbose --help

The variable values are listed near the end of the output. Make sure
that the `--verbose' and `--help' options are last.  Otherwise, the
effect of any options listed after them on the command line are not
reflected in the output.

For information on tuning the `InnoDB' storage engine, see *Note
innodb-tuning::.

MySQL Enterprise

For expert advice on tuning system parameters subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: controlling-optimizer,  Next: query-cache,  Prev: server-parameters,  Up: optimizing-the-server

7.5.4 Controlling Query Optimizer Performance
---------------------------------------------

The task of the query optimizer is to find an optimal plan for
executing an SQL query. Because the difference in performance between
`good' and `bad' plans can be orders of magnitude (that is, seconds
versus hours or even days), most query optimizers, including that of
MySQL, perform a more or less exhaustive search for an optimal plan
among all possible query evaluation plans. For join queries, the number
of possible plans investigated by the MySQL optimizer grows
exponentially with the number of tables referenced in a query.  For
small numbers of tables (typically less than 7-10) this is not a
problem. However, when larger queries are submitted, the time spent in
query optimization may easily become the major bottleneck in the
server's performance.

A more flexible method for query optimization allows the user to
control how exhaustive the optimizer is in its search for an optimal
query evaluation plan. The general idea is that the fewer plans that
are investigated by the optimizer, the less time it spends in compiling
a query. On the other hand, because the optimizer skips some plans, it
may miss finding an optimal plan.

The behavior of the optimizer with respect to the number of plans it
evaluates can be controlled via two system variables:

   * The `optimizer_prune_level' variable tells the optimizer to skip
     certain plans based on estimates of the number of rows accessed
     for each table. Our experience shows that this kind of `educated
     guess' rarely misses optimal plans, and may dramatically reduce
     query compilation times. That is why this option is on
     (`optimizer_prune_level=1') by default.  However, if you believe
     that the optimizer missed a better query plan, this option can be
     switched off (`optimizer_prune_level=0') with the risk that query
     compilation may take much longer. Note that, even with the use of
     this heuristic, the optimizer still explores a roughly exponential
     number of plans.

   * The `optimizer_search_depth' variable tells how far into the
     `future' of each incomplete plan the optimizer should look to
     evaluate whether it should be expanded further. Smaller values of
     `optimizer_search_depth' may result in orders of magnitude smaller
     query compilation times. For example, queries with 12, 13, or more
     tables may easily require hours and even days to compile if
     `optimizer_search_depth' is close to the number of tables in the
     query. At the same time, if compiled with `optimizer_search_depth'
     equal to 3 or 4, the optimizer may compile in less than a minute
     for the same query. If you are unsure of what a reasonable value
     is for `optimizer_search_depth', this variable can be set to 0 to
     tell the optimizer to determine the value automatically.


File: manual.info,  Node: query-cache,  Next: thread-information,  Prev: controlling-optimizer,  Up: optimizing-the-server

7.5.5 The MySQL Query Cache
---------------------------

* Menu:

* query-cache-operation::        How the Query Cache Operates
* query-cache-in-select::        Query Cache `SELECT' Options
* query-cache-configuration::    Query Cache Configuration
* query-cache-status-and-maintenance::  Query Cache Status and Maintenance

The query cache stores the text of a *Note `SELECT': select. statement
together with the corresponding result that was sent to the client. If
an identical statement is received later, the server retrieves the
results from the query cache rather than parsing and executing the
statement again. The query cache is shared among sessions, so a result
set generated by one client can be sent in response to the same query
issued by another client.

The query cache is extremely useful in an environment where you have
tables that do not change very often and for which the server receives
many identical queries. This is a typical situation for many Web
servers that generate many dynamic pages based on database content.

The query cache does not return stale data. When tables are modified,
any relevant entries in the query cache are flushed.

*Note*:

The query cache does not work in an environment where you have multiple
*Note `mysqld': mysqld. servers updating the same `MyISAM' tables.

Some performance data for the query cache follows. These results were
generated by running the MySQL benchmark suite on a Linux Alpha
2x500MHz system with 2GB RAM and a 64MB query cache.

   * If all the queries you are performing are simple (such as
     selecting a row from a table with one row), but still differ so
     that the queries cannot be cached, the overhead for having the
     query cache active is 13%. This could be regarded as the worst
     case scenario. In real life, queries tend to be much more
     complicated, so the overhead normally is significantly lower.

   * Searches for a single row in a single-row table are 238% faster
     with the query cache than without it. This can be regarded as
     close to the minimum speedup to be expected for a query that is
     cached.

To disable the query cache at server startup, set the
`query_cache_size' system variable to 0. By disabling the query cache
code, there is no noticeable overhead. If you build MySQL from source,
query cache capabilities can be excluded from the server entirely by
invoking `configure' with the `--without-query-cache' option.

The query cache offers the potential for substantial performance
improvement, but you should not assume that it will do so under all
circumstances. With some query cache configurations or server
workloads, you might actually see a performance decrease:

   * Be cautious about sizing the query cache excessively large, which
     increases the overhead required to maintain the cache, possibly
     beyond the benefit of enabling it. Sizes in tens of megabytes are
     usually beneficial. Sizes in the hundreds of megabytes might not
     be.

   * Server workload has a significant effect on query cache
     efficiency. A query mix consisting almost entirely of a fixed set
     of *Note `SELECT': select.  statements is much more likely to
     benefit from enabling the cache than a mix in which frequent *Note
     `INSERT': insert. statements cause continual invalidation of
     results in the cache. In some cases, a workaround is to use the
     `SQL_NO_CACHE' option to prevent results from even entering the
     cache for *Note `SELECT': select. statements that use frequently
     modified tables. (See *Note query-cache-in-select::.)

To verify that enabling the query cache is beneficial, test the
operation of your MySQL server with the cache enabled and disabled.
Then retest periodically because query cache efficiency may change as
server workload changes.


File: manual.info,  Node: query-cache-operation,  Next: query-cache-in-select,  Prev: query-cache,  Up: query-cache

7.5.5.1 How the Query Cache Operates
....................................

This section describes how the query cache works when it is
operational. *Note query-cache-configuration::, describes how to
control whether it is operational.

Incoming queries are compared to those in the query cache before
parsing, so the following two queries are regarded as different by the
query cache:

     SELECT * FROM TBL_NAME
     Select * from TBL_NAME

Queries must be _exactly_ the same (byte for byte) to be seen as
identical. In addition, query strings that are identical may be treated
as different for other reasons. Queries that use different databases,
different protocol versions, or different default character sets are
considered different queries and are cached separately.

The cache is not used for queries of the following types:

   * Queries that are a subquery of an outer query

   * Queries executed within the body of a stored function, trigger, or
     event

Before a query result is fetched from the query cache, MySQL checks
whether the user has *Note `SELECT': select. privilege for all
databases and tables involved. If this is not the case, the cached
result is not used.

If a query result is returned from query cache, the server increments
the `Qcache_hits' status variable, not `Com_select'. See *Note
query-cache-status-and-maintenance::.

If a table changes, all cached queries that use the table become
invalid and are removed from the cache. This includes queries that use
`MERGE' tables that map to the changed table. A table can be changed by
many types of statements, such as *Note `INSERT': insert, *Note
`UPDATE': update, *Note `DELETE': delete, *Note `TRUNCATE': truncate,
*Note `ALTER TABLE': alter-table, *Note `DROP TABLE': drop-table, or
*Note `DROP DATABASE': drop-database.

The query cache also works within transactions when using `InnoDB'
tables.

In MySQL 6.0, the result from a *Note `SELECT': select. query on a view
is cached.

The query cache works for `SELECT SQL_CALC_FOUND_ROWS ...' queries and
stores a value that is returned by a following `SELECT FOUND_ROWS()'
query.  `FOUND_ROWS()' returns the correct value even if the preceding
query was fetched from the cache because the number of found rows is
also stored in the cache. The `SELECT FOUND_ROWS()' query itself cannot
be cached.

Prepared statements that are issued via the binary protocol using *Note
`mysql_stmt_prepare()': mysql-stmt-prepare. and *Note
`mysql_stmt_execute()': mysql-stmt-execute. (see *Note
c-api-prepared-statements::), are subject to limitations on caching.
Comparison with statements in the query cache is based on the text of
the statement after expansion of `?' parameter markers. The statement
is compared only with other cached statements that were executed via
the binary protocol. That is, for query cache purposes, prepared
statements issued via the binary protocol are distinct from prepared
statements issued via the text protocol (see *Note
sql-syntax-prepared-statements::).

A query cannot be cached if it contains any of the functions shown in
the following table.

`BENCHMARK()'            `CONNECTION_ID()'        `CONVERT_TZ()'
`CURDATE()'              `CURRENT_DATE()'         `CURRENT_TIME()'
`CURRENT_TIMESTAMP()'    `CURTIME()'              `DATABASE()'
`ENCRYPT()' with one     `FOUND_ROWS()'           `GET_LOCK()'
parameter                                         
`LAST_INSERT_ID()'       `LOAD_FILE()'            `MASTER_POS_WAIT()'
`NOW()'                  `RAND()'                 `RELEASE_LOCK()'
`SLEEP()'                `SYSDATE()'              `UNIX_TIMESTAMP()' with
                                                  no parameters
`USER()'                 `UUID()'                 `UUID_SHORT()'

A query also is not cached under these conditions:

   * It refers to user-defined functions (UDFs) or stored functions.

   * It refers to user variables or local stored program variables.

   * It refers to tables in the `mysql' or `INFORMATION_SCHEMA' system
     database.

   * It is of any of the following forms:

          SELECT ... LOCK IN SHARE MODE
          SELECT ... FOR UPDATE
          SELECT ... INTO OUTFILE ...
          SELECT ... INTO DUMPFILE ...
          SELECT * FROM ... WHERE autoincrement_col IS NULL

     The last form is not cached because it is used as the ODBC
     workaround for obtaining the last insert ID value. See the MyODBC
     section of *Note connectors-apis::.

   * It uses `TEMPORARY' tables.

   * It does not use any tables.

   * It generates warnings.

   * The user has a column-level privilege for any of the involved
     tables.


File: manual.info,  Node: query-cache-in-select,  Next: query-cache-configuration,  Prev: query-cache-operation,  Up: query-cache

7.5.5.2 Query Cache `SELECT' Options
....................................

Two query cache-related options may be specified in *Note `SELECT':
select. statements:

   * `SQL_CACHE'

     The query result is cached if it is cacheable and the value of the
     `query_cache_type' system variable is `ON' or `DEMAND'.

   * `SQL_NO_CACHE'

     The query result is not cached.

Examples:

     SELECT SQL_CACHE id, name FROM customer;
     SELECT SQL_NO_CACHE id, name FROM customer;


File: manual.info,  Node: query-cache-configuration,  Next: query-cache-status-and-maintenance,  Prev: query-cache-in-select,  Up: query-cache

7.5.5.3 Query Cache Configuration
.................................

The `have_query_cache' server system variable indicates whether the
query cache is available:

     mysql> SHOW VARIABLES LIKE 'have_query_cache';
     +------------------+-------+
     | Variable_name    | Value |
     +------------------+-------+
     | have_query_cache | YES   |
     +------------------+-------+

When using a standard MySQL binary, this value is always `YES', even if
query caching is disabled.

Several other system variables control query cache operation.  These
can be set in an option file or on the command line when starting *Note
`mysqld': mysqld. The query cache system variables all have names that
begin with `query_cache_'. They are described briefly in *Note
server-system-variables::, with additional configuration information
given here.

To set the size of the query cache, set the `query_cache_size' system
variable. Setting it to 0 disables the query cache. The default size is
0, so the query cache is disabled by default.

MySQL Enterprise

For expert advice on configuring the query cache subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Note*:

When using the Windows Configuration Wizard to install or configure
MySQL, the default value for `query_cache_size' will be configured
automatically for you based on the different configuration types
available. When using the Windows Configuration Wizard, the query cache
may be enabled (that is, set to a non-zero value) due to the selected
configuration. The query cache is also controlled by the setting of the
`query_cache_type' variable.  You should check the values of these
variables as set in your `my.ini' file after configuration has taken
place.

When you set `query_cache_size' to a non-zero value, keep in mind that
the query cache needs a minimum size of about 40KB to allocate its
structures. (The exact size depends on system architecture.) If you set
the value too small, you'll get a warning, as in this example:

     mysql> SET GLOBAL query_cache_size = 40000;
     Query OK, 0 rows affected, 1 warning (0.00 sec)

     mysql> SHOW WARNINGS\G
     *************************** 1. row ***************************
       Level: Warning
        Code: 1282
     Message: Query cache failed to set size 39936;
              new query cache size is 0

     mysql> SET GLOBAL query_cache_size = 41984;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SHOW VARIABLES LIKE 'query_cache_size';
     +------------------+-------+
     | Variable_name    | Value |
     +------------------+-------+
     | query_cache_size | 41984 |
     +------------------+-------+

For the query cache to actually be able to hold any query results, its
size must be set larger:

     mysql> SET GLOBAL query_cache_size = 1000000;
     Query OK, 0 rows affected (0.04 sec)

     mysql> SHOW VARIABLES LIKE 'query_cache_size';
     +------------------+--------+
     | Variable_name    | Value  |
     +------------------+--------+
     | query_cache_size | 999424 |
     +------------------+--------+
     1 row in set (0.00 sec)

The `query_cache_size' value is aligned to the nearest 1024 byte block.
The value reported may therefore be different from the value that you
assign.

If the query cache size is greater than 0, the `query_cache_type'
variable influences how it works. This variable can be set to the
following values:

   * A value of `0' or `OFF' prevents caching or retrieval of cached
     results.

   * A value of `1' or `ON' allows caching except of those statements
     that begin with `SELECT SQL_NO_CACHE'.

   * A value of `2' or `DEMAND' causes caching of only those statements
     that begin with `SELECT SQL_CACHE'.

Setting the `GLOBAL' `query_cache_type' value determines query cache
behavior for all clients that connect after the change is made.
Individual clients can control cache behavior for their own connection
by setting the `SESSION' `query_cache_type' value. For example, a
client can disable use of the query cache for its own queries like this:

     mysql> SET SESSION query_cache_type = OFF;

If you set `query_cache_type' at server startup (rather than at runtime
with a *Note `SET': set-option.  statement), only the numeric values
are allowed.

To control the maximum size of individual query results that can be
cached, set the `query_cache_limit' system variable. The default value
is 1MB.

*Note*:

You can set the maximum size that can be specified for the query cache
at run time with the *Note `SET': set-option.  statement by using the
`--maximum-query_cache_size=32M' option on the command line or in the
configuration file.

When a query is to be cached, its result (the data sent to the client)
is stored in the query cache during result retrieval.  Therefore the
data usually is not handled in one big chunk.  The query cache
allocates blocks for storing this data on demand, so when one block is
filled, a new block is allocated.  Because memory allocation operation
is costly (timewise), the query cache allocates blocks with a minimum
size given by the `query_cache_min_res_unit' system variable. When a
query is executed, the last result block is trimmed to the actual data
size so that unused memory is freed. Depending on the types of queries
your server executes, you might find it helpful to tune the value of
`query_cache_min_res_unit':

   * The default value of `query_cache_min_res_unit' is 4KB. This
     should be adequate for most cases.

   * If you have a lot of queries with small results, the default block
     size may lead to memory fragmentation, as indicated by a large
     number of free blocks. Fragmentation can force the query cache to
     prune (delete) queries from the cache due to lack of memory. In
     this case, you should decrease the value of
     `query_cache_min_res_unit'.  The number of free blocks and queries
     removed due to pruning are given by the values of the
     `Qcache_free_blocks' and `Qcache_lowmem_prunes' status variables.

   * If most of your queries have large results (check the
     `Qcache_total_blocks' and `Qcache_queries_in_cache' status
     variables), you can increase performance by increasing
     `query_cache_min_res_unit'.  However, be careful to not make it
     too large (see the previous item).

MySQL Enterprise

If the query cache is under-utilized, performance will suffer. Advice
on avoiding this problem is provided to subscribers to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: query-cache-status-and-maintenance,  Prev: query-cache-configuration,  Up: query-cache

7.5.5.4 Query Cache Status and Maintenance
..........................................

You can check whether the query cache is present in your MySQL server
using the following statement:

     mysql> SHOW VARIABLES LIKE 'have_query_cache';
     +------------------+-------+
     | Variable_name    | Value |
     +------------------+-------+
     | have_query_cache | YES   |
     +------------------+-------+

You can defragment the query cache to better utilize its memory with
the *Note `FLUSH QUERY CACHE': flush. statement. The statement does not
remove any queries from the cache.

The `RESET QUERY CACHE' statement removes all query results from the
query cache. The *Note `FLUSH TABLES': flush.  statement also does this.

To monitor query cache performance, use *Note `SHOW STATUS':
show-status. to view the cache status variables:

     mysql> SHOW STATUS LIKE 'Qcache%';
     +-------------------------+--------+
     | Variable_name           | Value  |
     +-------------------------+--------+
     | Qcache_free_blocks      | 36     |
     | Qcache_free_memory      | 138488 |
     | Qcache_hits             | 79570  |
     | Qcache_inserts          | 27087  |
     | Qcache_lowmem_prunes    | 3114   |
     | Qcache_not_cached       | 22989  |
     | Qcache_queries_in_cache | 415    |
     | Qcache_total_blocks     | 912    |
     +-------------------------+--------+

Descriptions of each of these variables are given in *Note
server-status-variables::. Some uses for them are described here.

The total number of *Note `SELECT': select.  queries is given by this
formula:

       Com_select
     + Qcache_hits
     + queries with errors found by parser

The `Com_select' value is given by this formula:

       Qcache_inserts
     + Qcache_not_cached
     + queries with errors found during the column-privileges check

The query cache uses variable-length blocks, so `Qcache_total_blocks'
and `Qcache_free_blocks' may indicate query cache memory fragmentation.
After *Note `FLUSH QUERY CACHE': flush, only a single free block
remains.

Every cached query requires a minimum of two blocks (one for the query
text and one or more for the query results). Also, every table that is
used by a query requires one block.  However, if two or more queries
use the same table, only one table block needs to be allocated.

The information provided by the `Qcache_lowmem_prunes' status variable
can help you tune the query cache size. It counts the number of queries
that have been removed from the cache to free up memory for caching new
queries. The query cache uses a least recently used (LRU) strategy to
decide which queries to remove from the cache. Tuning information is
given in *Note query-cache-configuration::.


File: manual.info,  Node: thread-information,  Next: connection-threads,  Prev: query-cache,  Up: optimizing-the-server

7.5.6 Examining Thread Information
----------------------------------

* Menu:

* thread-commands::              Thread Command Values
* general-thread-states::        General Thread States
* delayed-insert-thread-states::  Delayed-Insert Thread States
* master-thread-states::         Replication Master Thread States
* slave-io-thread-states::       Replication Slave I/O Thread States
* slave-sql-thread-states::      Replication Slave SQL Thread States
* slave-connection-thread-states::  Replication Slave Connection Thread States
* event-scheduler-thread-states::  Event Scheduler Thread States

When you are attempting to ascertain what your MySQL server is doing,
it can be helpful to examine the process list, which is the set of
threads currently executing within the server.  Process list
information is available from these sources:

   * The `SHOW [FULL] PROCESSLIST' statement (*Note show-processlist::)

   * The *Note `SHOW PROFILE': show-profile. statement (*Note
     show-profiles::)

   * The `INFORMATION_SCHEMA' *Note `PROCESSLIST': processlist-table.
     table (*Note processlist-table::)

   * The *Note `mysqladmin processlist': mysqladmin. command (*Note
     mysqladmin::)

You can always view information about your own threads. To view
information about threads being executed for other accounts, you must
have the `PROCESS' privilege.

Each process list entry contains several pieces of information:

   * `Id' is the connection identifier for the client associated with
     the thread.

   * `User' and `Host' indicate the account associated with the thread.

   * `db' is the default database for the thread, or `NULL' if none is
     selected.

   * `Command' and `State' indicate what the thread is doing.

     Most states correspond to very quick operations. If a thread stays
     in a given state for many seconds, there might be a problem that
     needs to be investigated.

   * `Time' indicates how long the thread has been in its current
     state. The thread's notion of the current time may be altered in
     some cases: The thread can change the time with *Note `SET
     TIMESTAMP = VALUE': set-option. For a thread running on a slave
     that is processing events from the master, the thread time is set
     to the time found in the events and thus reflects current time on
     the master and not the slave.

   * `Info' contains the text of the statement being executed by the
     thread, or `NULL' if it is not executing one. By default, this
     value contains only the first 100 characters of the statement. To
     see the complete statements, use *Note `SHOW FULL PROCESSLIST':
     show-processlist.

The following sections list the possible `Command' values, and `State'
values grouped by category. The meaning for some of these values is
self-evident. For others, additional description is provided.


File: manual.info,  Node: thread-commands,  Next: general-thread-states,  Prev: thread-information,  Up: thread-information

7.5.6.1 Thread Command Values
.............................

A thread can have any of the following `Command' values:

   * `Binlog Dump'

     This is a thread on a master server for sending binary log
     contents to a slave server.

   * `Change user'

     The thread is executing a change-user operation.

   * `Close stmt'

     The thread is closing a prepared statement.

   * `Connect'

     A replication slave is connected to its master.

   * `Connect Out'

     A replication slave is connecting to its master.

   * `Create DB'

     The thread is executing a create-database operation.

   * `Daemon'

     This thread is internal to the server, not a thread that services
     a client connection.

   * `Debug'

     The thread is generating debugging information.

   * `Delayed insert'

     The thread is a delayed-insert handler.

   * `Drop DB'

     The thread is executing a drop-database operation.

   * `Error'

   * `Execute'

     The thread is executing a prepared statement.

   * `Fetch'

     The thread is fetching the results from executing a prepared
     statement.

   * `Field List'

     The thread is retrieving information for table columns.

   * `Init DB'

     The thread is selecting a default database.

   * `Kill'

     The thread is killing another thread.

   * `Long Data'

     The thread is retrieving long data in the result of executing a
     prepared statement.

   * `Ping'

     The thread is handling a server-ping request.

   * `Prepare'

     The thread is preparing a prepared statement.

   * `Processlist'

     The thread is producing information about server threads.

   * `Query'

     The thread is executing a statement.

   * `Quit'

     The thread is terminating.

   * `Refresh'

     The thread is flushing table, logs, or caches, or resetting status
     variable or replication server information.

   * `Register Slave'

     The thread is registering a slave server.

   * `Reset stmt'

     The thread is resetting a prepared statement.

   * `Set option'

     The thread is setting or resetting a client statement-execution
     option.

   * `Shutdown'

     The thread is shutting down the server.

   * `Sleep'

     The thread is waiting for the client to send a new statement to it.

   * `Statistics'

     The thread is producing server-status information.

   * `Table Dump'

     The thread is sending table contents to a slave server.

   * `Time'

     Unused.


File: manual.info,  Node: general-thread-states,  Next: delayed-insert-thread-states,  Prev: thread-commands,  Up: thread-information

7.5.6.2 General Thread States
.............................

The following list describes thread `State' values that are associated
with general query processing and not more specialized activities such
as replication. Many of these are useful only for finding bugs in the
server.

   * `After create'

     Occurs when the thread creates a table (including internal
     temporary tables), at the end of the function that creates the
     table. This state is used even if the table could not be created
     due to some error.

   * `Analyzing'

     The thread is calculating a `MyISAM' table key distributions (for
     example, for *Note `ANALYZE TABLE': analyze-table.).

   * `checking permissions'

     The thread is checking whether the server has the required
     privileges to execute the statement.

   * `Checking table'

     The thread is performing a table check operation.

   * `cleaning up'

     The thread has processed one command and is preparing to free
     memory and reset certain state variables.

   * `closing tables'

     Means that the thread is flushing the changed table data to disk
     and closing the used tables. This should be a fast operation. If
     not, you should verify that you do not have a full disk and that
     the disk is not in very heavy use.

   * `converting HEAP to MyISAM'

     The thread is converting an internal temporary table from a
     `MEMORY' table to an on-disk `MyISAM' table.

   * `copy to tmp table'

     The thread is processing an *Note `ALTER TABLE': alter-table.
     statement. This state occurs after the table with the new
     structure has been created but before rows are copied into it.

   * `Copying to group table'

     If a statement has different `ORDER BY' and `GROUP BY' criteria,
     the rows are sorted by group and copied to a temporary table.

   * `Copying to tmp table'

     The server is copying to a temporary table in memory.

   * `Copying to tmp table on disk'

     The server is copying to a temporary table on disk. The temporary
     result set was larger than `tmp_table_size' and the thread is
     changing the temporary table from in-memory to disk-based format
     to save memory.

   * `Creating index'

     The thread is processing `ALTER TABLE ... ENABLE KEYS' for a
     `MyISAM' table.

   * `Creating sort index'

     The thread is processing a *Note `SELECT': select. that is resolved
     using an internal temporary table.

   * `creating table'

     The thread is creating a table. This includes creation of
     temporary tables.

   * `Creating tmp table'

     The thread is creating a temporary table in memory or on disk. If
     the table is created in memory but later is converted to an
     on-disk table, the state during that operation will be `Copying to
     tmp table on disk'.

   * `deleting from main table'

     The server is executing the first part of a multiple-table delete.
     It is deleting only from the first table, and saving columns and
     offsets to be used for deleting from the other (reference) tables.

   * `deleting from reference tables'

     The server is executing the second part of a multiple-table delete
     and deleting the matched rows from the other tables.

   * `discard_or_import_tablespace'

     The thread is processing an `ALTER TABLE ...  DISCARD TABLESPACE'
     or `ALTER TABLE ...  IMPORT TABLESPACE' statement.

   * `end'

     This occurs at the end but before the cleanup of *Note `ALTER
     TABLE': alter-table, *Note `CREATE VIEW': create-view, *Note
     `DELETE': delete, *Note `INSERT': insert, *Note `SELECT': select,
     or *Note `UPDATE': update. statements.

   * `executing'

     The thread has begun executing a statement.

   * `Execution of init_command'

     The thread is executing statements in the value of the
     `init_command' system variable.

   * `freeing items'

     The thread has executed a command. This state is usually followed
     by `cleaning up'.

   * `Flushing tables'

     The thread is executing *Note `FLUSH TABLES': flush. and is
     waiting for all threads to close their tables.

   * `FULLTEXT initialization'

     The server is preparing to perform a natural-language full-text
     search.

   * `init'

     This occurs before the initialization of *Note `ALTER TABLE':
     alter-table, *Note `DELETE': delete, *Note `INSERT': insert, *Note
     `SELECT': select, or *Note `UPDATE': update. statements.

   * `Killed'

     Someone has sent a *Note `KILL': kill.  statement to the thread
     and it should abort next time it checks the kill flag. The flag is
     checked in each major loop in MySQL, but in some cases it might
     still take a short time for the thread to die. If the thread is
     locked by some other thread, the kill takes effect as soon as the
     other thread releases its lock.

   * `Locked'

     The query is locked by another query.

   * `logging slow query'

     The thread is writing a statement to the slow-query log.

   * `NULL'

     This state is used for the *Note `SHOW PROCESSLIST':
     show-processlist. state.

   * `login'

     The initial state for a connection thread until the client has
     been authenticated successfully.

   * `Opening tables', `Opening table'

     The thread is trying to open a table. This is should be very fast
     procedure, unless something prevents opening.  For example, an
     *Note `ALTER TABLE': alter-table.  or a *Note `LOCK TABLE':
     lock-tables. statement can prevent opening a table until the
     statement is finished.

   * `preparing'

     This state occurs during query optimization.

   * `Purging old relay logs'

     The thread is removing unneeded relay log files.

   * `query end'

     This state occurs after processing a query but before the `freeing
     items' state.

   * `Reading from net'

     The server is reading a packet from the network.

   * `Removing duplicates'

     The query was using `SELECT DISTINCT' in such a way that MySQL
     could not optimize away the distinct operation at an early stage.
     Because of this, MySQL requires an extra stage to remove all
     duplicated rows before sending the result to the client.

   * `removing tmp table'

     The thread is removing an internal temporary table after
     processing a *Note `SELECT': select.  statement. This state is not
     used if no temporary table was created.

   * `rename'

     The thread is renaming a table.

   * `rename result table'

     The thread is processing an *Note `ALTER TABLE': alter-table.
     statement, has created the new table, and is renaming it to
     replace the original table.

   * `Reopen tables'

     The thread got a lock for the table, but noticed after getting the
     lock that the underlying table structure changed. It has freed the
     lock, closed the table, and is trying to reopen it.

   * `Repair by sorting'

     The repair code is using a sort to create indexes.

   * `Repair done'

     The thread has completed a multi-threaded repair for a `MyISAM'
     table.

   * `Repair with keycache'

     The repair code is using creating keys one by one through the key
     cache. This is much slower than `Repair by sorting'.

   * `Rolling back'

     The thread is rolling back a transaction.

   * `Saving state'

     For `MyISAM' table operations such as repair or analysis, the
     thread is saving the new table state to the `.MYI' file header.
     State includes information such as number of rows, the
     `AUTO_INCREMENT' counter, and key distributions.

   * `Searching rows for update'

     The thread is doing a first phase to find all matching rows before
     updating them. This has to be done if the *Note `UPDATE': update.
     is changing the index that is used to find the involved rows.

   * `Sending data'

     The thread is processing rows for a *Note `SELECT': select.
     statement and also is sending data to the client.

   * `setup'

     The thread is beginning an *Note `ALTER TABLE': alter-table.
     operation.

   * `Sorting for group'

     The thread is doing a sort to satisfy a `GROUP BY'.

   * `Sorting for order'

     The thread is doing a sort to satisfy a `ORDER BY'.

   * `Sorting index'

     The thread is sorting index pages for more efficient access during
     a `MyISAM' table optimization operation.

   * `Sorting result'

     For a *Note `SELECT': select. statement, this is similar to
     `Creating sort index', but for non-temporary tables.

   * `statistics'

     The server is calculating statistics to develop a query execution
     plan.

   * `System lock'

     The thread is going to request or is waiting for an internal or
     external system lock for the table. If this state is being caused
     by requests for external locks and you are not using multiple
     *Note `mysqld': mysqld.  servers that are accessing the same
     tables, you can disable external system locks with the
     `--skip-external-locking' option. However, external locking is
     disabled by default, so it is likely that this option will have no
     effect. For *Note `SHOW PROFILE': show-profile, this state means
     the thread is requesting the lock (not waiting for it).

   * `Table lock'

     The next thread state after `System lock'. The thread has acquired
     an external lock and is going to request an internal table lock.

   * `Updating'

     The thread is searching for rows to update and is updating them.

   * `updating main table'

     The server is executing the first part of a multiple-table update.
     It is updating only the first table, and saving columns and
     offsets to be used for updating the other (reference) tables.

   * `updating reference tables'

     The server is executing the second part of a multiple-table update
     and updating the matched rows from the other tables.

   * `User lock'

     The thread is going to request or is waiting for an advisory lock
     requested with a `GET_LOCK()' call. For *Note `SHOW PROFILE':
     show-profile, this state means the thread is requesting the lock
     (not waiting for it).

   * `Waiting for tables', `Waiting for table'

     The thread got a notification that the underlying structure for a
     table has changed and it needs to reopen the table to get the new
     structure. However, to reopen the table, it must wait until all
     other threads have closed the table in question.

     This notification takes place if another thread has used *Note
     `FLUSH TABLES': flush. or one of the following statements on the
     table in question: `FLUSH TABLES TBL_NAME', *Note `ALTER TABLE':
     alter-table, *Note `RENAME TABLE': rename-table, *Note `REPAIR
     TABLE': repair-table, *Note `ANALYZE TABLE': analyze-table, or
     *Note `OPTIMIZE TABLE': optimize-table.

   * `Waiting on cond'

     A generic state in which the thread is waiting for a condition to
     become true. No specific state information is available.

   * `Writing to net'

     The server is writing a packet to the network.


File: manual.info,  Node: delayed-insert-thread-states,  Next: master-thread-states,  Prev: general-thread-states,  Up: thread-information

7.5.6.3 Delayed-Insert Thread States
....................................

These thread states are associated with processing for `DELAYED'
inserts (see *Note insert-delayed::). Some states are associated with
connection threads that process *Note `INSERT DELAYED': insert-delayed.
statements from clients. Other states are associated with delayed-insert
handler threads that insert the rows. There is a delayed-insert handler
thread for each table for which *Note `INSERT DELAYED': insert-delayed.
statements are issued.

States associated with a connection thread that processes an *Note
`INSERT DELAYED': insert-delayed. statement from the client:

   * `allocating local table'

     The thread is preparing to feed rows to the delayed-insert handler
     thread.

   * `Creating delayed handler'

     The thread is creating a handler for `DELAYED' inserts.

   * `got handler lock'

     This occurs before the `allocating local table' state and after
     the `waiting for handler lock' state, when the connection thread
     gets access to the delayed-insert handler thread.

   * `got old table'

     This occurs after the `waiting for handler open' state. The
     delayed-insert handler thread has signaled that it has ended its
     initialization phase, which includes opening the table for delayed
     inserts.

   * `storing row into queue'

     The thread is adding a new row to the list of rows that the
     delayed-insert handler thread must insert.

   * `update'

   * `waiting for delay_list'

     This occurs during the initialization phase when the thread is
     trying to find the delayed-insert handler thread for the table,
     and before attempting to gain access to the list of delayed-insert
     threads.

   * `waiting for handler insert'

     An *Note `INSERT DELAYED': insert-delayed. handler has processed
     all pending inserts and is waiting for new ones.

   * `waiting for handler lock'

     This occurs before the `allocating local table' state when the
     connection thread waits for access to the delayed-insert handler
     thread.

   * `waiting for handler open'

     This occurs after the `Creating delayed handler' state and before
     the `got old table' state. The delayed-insert handler thread has
     just been started, and the connection thread is waiting for it to
     initialize.

States associated with a delayed-insert handler thread that inserts the
rows:

   * `insert'

     The state that occurs just before inserting rows into the table.

   * `reschedule'

     After inserting a number of rows, the delayed-insert thread sleeps
     to let other threads do work.

   * `upgrading lock'

     A delayed-insert handler is trying to get a lock for the table to
     insert rows.

   * `Waiting for INSERT'

     A delayed-insert handler is waiting for a connection thread to add
     rows to the queue (see `storing row into queue').


File: manual.info,  Node: master-thread-states,  Next: slave-io-thread-states,  Prev: delayed-insert-thread-states,  Up: thread-information

7.5.6.4 Replication Master Thread States
........................................

The following list shows the most common states you may see in the
`State' column for the master's `Binlog Dump' thread. If you see no
`Binlog Dump' threads on a master server, this means that replication
is not running -- that is, that no slaves are currently connected.

   * `Sending binlog event to slave'

     Binary logs consist of _events_, where an event is usually an
     update plus some other information.  The thread has read an event
     from the binary log and is now sending it to the slave.

   * `Finished reading one binlog; switching to next binlog'

     The thread has finished reading a binary log file and is opening
     the next one to send to the slave.

   * `Has sent all binlog to slave; waiting for binlog to be updated'

     The thread has read all outstanding updates from the binary logs
     and sent them to the slave. The thread is now idle, waiting for
     new events to appear in the binary log resulting from new updates
     occurring on the master.

   * `Waiting to finalize termination'

     A very brief state that occurs as the thread is stopping.


File: manual.info,  Node: slave-io-thread-states,  Next: slave-sql-thread-states,  Prev: master-thread-states,  Up: thread-information

7.5.6.5 Replication Slave I/O Thread States
...........................................

The following list shows the most common states you see in the `State'
column for a slave server I/O thread.  This state also appears in the
`Slave_IO_State' column displayed by *Note `SHOW SLAVE STATUS':
show-slave-status, so you can get a good view of what is happening by
using that statement.

   * `Waiting for master update'

     The initial state before `Connecting to master'.

   * `Connecting to master'

     The thread is attempting to connect to the master.

   * `Checking master version'

     A state that occurs very briefly, after the connection to the
     master is established.

   * `Registering slave on master'

     A state that occurs very briefly after the connection to the
     master is established.

   * `Requesting binlog dump'

     A state that occurs very briefly, after the connection to the
     master is established. The thread sends to the master a request
     for the contents of its binary logs, starting from the requested
     binary log file name and position.

   * `Waiting to reconnect after a failed binlog dump request'

     If the binary log dump request failed (due to disconnection), the
     thread goes into this state while it sleeps, then tries to
     reconnect periodically. The interval between retries can be
     specified using the *Note `CHANGE MASTER TO': change-master-to.
     statement.

   * `Reconnecting after a failed binlog dump request'

     The thread is trying to reconnect to the master.

   * `Waiting for master to send event'

     The thread has connected to the master and is waiting for binary
     log events to arrive. This can last for a long time if the master
     is idle. If the wait lasts for `slave_net_timeout'
     (http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_net_timeout)
     seconds, a timeout occurs. At that point, the thread considers the
     connection to be broken and makes an attempt to reconnect.

   * `Queueing master event to the relay log'

     The thread has read an event and is copying it to the relay log so
     that the SQL thread can process it.

   * `Waiting to reconnect after a failed master event read'

     An error occurred while reading (due to disconnection).  The
     thread is sleeping for the number of seconds set by the *Note
     `CHANGE MASTER TO': change-master-to.  statement (default 60)
     before attempting to reconnect.

   * `Reconnecting after a failed master event read'

     The thread is trying to reconnect to the master. When connection
     is established again, the state becomes `Waiting for master to
     send event'.

   * `Waiting for the slave SQL thread to free enough relay log space'

     You are using a non-zero `relay_log_space_limit' value, and the
     relay logs have grown large enough that their combined size
     exceeds this value. The I/O thread is waiting until the SQL thread
     frees enough space by processing relay log contents so that it can
     delete some relay log files.

   * `Waiting for slave mutex on exit'

     A state that occurs briefly as the thread is stopping.


File: manual.info,  Node: slave-sql-thread-states,  Next: slave-connection-thread-states,  Prev: slave-io-thread-states,  Up: thread-information

7.5.6.6 Replication Slave SQL Thread States
...........................................

The following list shows the most common states you may see in the
`State' column for a slave server SQL thread:

   * `Waiting for the next event in relay log'

     The initial state before `Reading event from the relay log'.

   * `Reading event from the relay log'

     The thread has read an event from the relay log so that the event
     can be processed.

   * `Has read all relay log; waiting for the slave I/O thread to
     update it'

     The thread has processed all events in the relay log files, and is
     now waiting for the I/O thread to write new events to the relay
     log.

   * `Making temp file'

     The thread is executing a *Note `LOAD DATA INFILE': load-data.
     statement and is creating a temporary file containing the data
     from which the slave will read rows.

   * `Waiting for slave mutex on exit'

     A very brief state that occurs as the thread is stopping.

The `State' column for the I/O thread may also show the text of a
statement. This indicates that the thread has read an event from the
relay log, extracted the statement from it, and is executing it.


File: manual.info,  Node: slave-connection-thread-states,  Next: event-scheduler-thread-states,  Prev: slave-sql-thread-states,  Up: thread-information

7.5.6.7 Replication Slave Connection Thread States
..................................................

These thread states occur on a replication slave but are associated
with connection threads, not with the I/O or SQL threads.

   * `Changing master'

     The thread is processing a *Note `CHANGE MASTER TO':
     change-master-to. statement.

   * `Killing slave'

     The thread is processing a `SLAVE STOP' statement.

   * `Opening master dump table'

     This state occurs after `Creating table from master dump'.

   * `Reading master dump table data'

     This state occurs after `Opening master dump table'.

   * `Rebuilding the index on master dump table'

     This state occurs after `Reading master dump table data'.


File: manual.info,  Node: event-scheduler-thread-states,  Prev: slave-connection-thread-states,  Up: thread-information

7.5.6.8 Event Scheduler Thread States
.....................................

These states occur for the Event Scheduler thread, threads that are
created to execute scheduled events, or threads that terminate the
scheduler.

   * `Clearing'

     The scheduler thread or a thread that was executing an event is
     terminating and is about to end.

   * `Initialized'

     The scheduler thread or a thread that will execute an event has
     been initialized.

   * `Waiting for next activation'

     The scheduler has a non-empty event queue but the next activation
     is in the future.

   * `Waiting for scheduler to stop'

     The thread issued `SET GLOBAL event_scheduler=OFF' and is waiting
     for the scheduler to stop.

   * `Waiting on empty queue'

     The scheduler's event queue is empty and it is sleeping.


File: manual.info,  Node: connection-threads,  Next: memory-use,  Prev: thread-information,  Up: optimizing-the-server

7.5.7 How MySQL Uses Threads for Client Connections
---------------------------------------------------

Connection manager threads handle client connection requests on the
network interfaces that the server listens to. On all platforms, one
manager thread handles TCP/IP connection requests. On Unix, this
manager thread also handles Unix socket file connection requests. On
Windows, a manager thread handles shared-memory connection requests,
and another handles named-pipe connection requests. The server does not
create threads to handle interfaces that it does not listen to. For
example, a Windows server that does not have support for named-pipe
connections enabled does not create a thread to handle them.

In the original thread model for handing client connections, connection
manager threads associate each client connection with a thread
dedicated to it that handles authentication and request processing for
that connection. Manager threads create a new thread when necessary but
try to avoid doing so by consulting the thread cache first to see
whether it contains a thread that can be used for the connection. When
a connection ends, its thread is returned to the thread cache if the
cache is not full.

The original connection thread model uses as many threads as there are
clients currently connected, which has some disadvantages when server
workload must scale to handle large numbers of connections. For
example, thread creation and disposal becomes expensive. Also, each
thread requires server and kernel resources, such as stack space. To
accommodate a large number of simultaneous connections, the stack size
per thread must be kept small, leading to a situation where it is
either too small or the server consumes large amounts of memory.
Exhaustion of other resources can occur as well, and scheduling
overhead can become significant.

As of MySQL 6.0.4, an alternative thread model is available for dealing
with the preceding issues that occur when scaling to large numbers of
simultaneous connections. This model uses thread pooling:

   * Connection manager threads do not dedicate a thread to each client
     connection. Instead, the connection is added to the set of
     existing connection sockets. The server collects input from these
     sockets and when a complete request has been received from a given
     client, it is queued for service.

   * The server maintains a pool of service threads to process client
     requests. When a queued request is waiting and there is an
     available (not busy) service thread in the pool, the request is
     given to the thread to be handled. After processing the request,
     the service thread becomes available to process other requests.

   * Service threads are created at server startup and exist until the
     server terminates. A given service thread is not tied to a
     specific client connection and the requests that it processes over
     time may originate from different client connections.

   * The pool of service threads has a fixed size, so the amount of
     memory required for it does not increase as the number of client
     connections increases.

Thread pooling works best if the normal workload consists mostly of
lightweight queries, with no more than a few simultaneous transactions
or long-running statements.

Thread pooling is less suitable when you have N threads in the pool but
it is possible that all or most of the threads will be tied up
servicing transactions or long-running statements simultaneously. If
this happens, the workload from other clients will be stalled.
Configuring the server to use a pool larger than the maximum number of
simultaneous transactions or long-running statements will help in this
case.

The following examples illustrate when a too-small thread pool might
cause problems. Assume a thread pool size of 1 for simplicity, but the
same issues can occur for a larger pool and larger number of clients.

   * One client issues a statement that takes a long time to process.
     This ties up the service thread. If other clients issue
     statements, they are queued and must wait for the statement
     currently executing to finish.

   * One client acquires an exclusive lock on a table. If another
     client attempts to use the table, its statement blocks and the
     service thread remains occupied waiting for the block to end. Any
     further statements from the original client cannot execute,
     either, because there is no free thread available.

     In the following scenario, conflicting lock requests cause
     deadlock.

     Session 1:

          LOCK TABLES t1 WRITE;

     The service thread executes the statement and becomes free.

     Session 2:

          LOCK TABLES t1 WRITE;

     The service thread starts to execute the statement but blocks
     waiting for the exiting lock on `t1' to be released. The thread
     does not become free.

     Session 1:

          INSERT INTO t1 VALUES(1,2);

     The statement cannot execute and is queued because the service
     thread remains allocated to session 2. At this point, the clients
     are deadlocked and neither cannot continue.

     A similar situation can occur in the absence of explicit locks if
     simultaneous transactions attempt to access tables such that one
     transaction blocks another. Assume that `t1' is an `InnoDB' table.

     Session 1:

          START TRANSACTION;
          SELECT * FROM t1 WHERE id = 7 FOR UPDATE;

     The service thread executes each of the statements in turn and
     becomes free. The *Note `SELECT': select.  statement acquires an
     exclusive lock for the selected row or rows.

     Session 2:

          START TRANSACTION;
          UPDATE t1 SET a = a+1 WHERE id = 7;

     The service thread executes the first statement and attempts to
     execute the second. However, the *Note `UPDATE': update. blocks
     because it must lock the same rows already locked by session 1, so
     the service thread waits and does not become free.

     Session 1:

          COMMIT;

     The statement cannot execute and is queued because the service
     thread remains allocated to the session 2 statement.  At this
     point, the transactions are deadlocked. Eventually, `InnoDB' times
     out waiting for the lock and the session 2 *Note `UPDATE': update.
     fails with an error. The service thread becomes free and executes
     the *Note `COMMIT': commit. for session 1.

Thread pooling is based on the `libevent' library. To build a server
that includes the thread-pool capability, configure MySQL using the
`--with-libevent' option. The `--without-libevent' option excludes the
`libevent' code. See *Note configure-options::.

To control which thread model the server uses to manage threads that
handle client connections and to monitor thread use, several system and
status variables are relevant:

   * At server startup, the `thread_handling' system variable controls
     which thread model is used.
     `--thread_handling=one-thread-per-connection' is the default and
     selects the model that allocates one thread per connected client
     (the original thread model). To use thread pooling, start the
     server with `--thread_handling=pool-of-threads'.  If `libevent' is
     not compiled into the server, `thread_handling' is unavailable and
     the server defaults to one thread per client.

   * When the server uses thread pooling, `thread_pool_size' controls
     the maximum number of requests that the server should be allowed
     to process simultaneously. The pool has a fixed size over the
     lifetime of server execution, but the size can be specified at
     startup. The default pool size is 20 threads.  Starting the server
     with `--thread_pool_size=N' sets the size to N threads, up to a
     maximum of 16,384. If `libevent' is not compiled into the server,
     `thread_pool_size' is unavailable.

     With thread pooling enabled, InnoDB concurrency control becomes
     unnecessary, so you can disable InnoDB thread concurrency by
     setting `innodb_thread_concurrency' to 0.

   * When the server uses one thread per client connection, it uses the
     thread cache, which has a size determined by the
     `thread_cache_size' system variable. The default value is 0 (no
     caching), which causes a thread to be set up for each new
     connection and disposed of when the connection terminates. Set
     `thread_cache_size' to N to allow N inactive connection threads to
     be cached.  `thread_cache_size' can be set at server startup or
     changed while the server runs. A connection thread becomes
     inactive when the client connection with which it was associated
     terminates.

     To monitor the number of threads in the cache and how many threads
     have been created because a thread could not be taken from the
     cache, monitor the `Threads_cached' and `Threads_created' status
     variables. (See *Note server-status-variables::.)

   * Regardless of thread model, you can set `max_connections' at server
     startup or at runtime to control the maximum number of clients
     that can connect simultaneously.

   * When the thread stack is too small, this limits the complexity of
     the SQL statements which the server can handle, the recursion
     depth of stored procedures, and other memory-consuming actions. To
     set a stack size of N bytes for each thread, start the server with
     `--thread_stack=N'.

For more information on these system and status variables, see *Note
server-system-variables::, and *Note server-status-variables::.


File: manual.info,  Node: memory-use,  Next: large-page-support,  Prev: connection-threads,  Up: optimizing-the-server

7.5.8 How MySQL Uses Memory
---------------------------

The following list indicates some of the ways that the *Note `mysqld':
mysqld. server uses memory. Where applicable, the name of the system
variable relevant to the memory use is given:

   * The key buffer is shared by all threads; its size is determined by
     the `key_buffer_size' variable.  Other buffers used by the server
     are allocated as needed.  See *Note server-parameters::.

   * Each thread that is used to manage client connections uses some
     thread-specific space. The following list indicates these and
     which variables control their size:

        * A stack (default 192KB, variable `thread_stack')

        * A connection buffer (variable `net_buffer_length')

        * A result buffer (variable `net_buffer_length')

     The connection buffer and result buffer both begin with a size
     given by `net_buffer_length' but are dynamically enlarged up to
     `max_allowed_packet' bytes as needed. The result buffer shrinks to
     `net_buffer_length' after each SQL statement. While a statement is
     running, a copy of the current statement string is also allocated.

   * All threads share the same base memory.

   * When a thread is no longer needed, the memory allocated to it is
     released and returned to the system unless the thread goes back
     into the thread cache. In that case, the memory remains allocated.

   * The `myisam_use_mmap' system variable can be set to 1 to enable
     memory-mapping for all `MyISAM' tables.

   * Each request that performs a sequential scan of a table allocates
     a _read buffer_ (variable `read_buffer_size').

   * When reading rows in an arbitrary sequence (for example, following
     a sort), a _random-read buffer_ (variable `read_rnd_buffer_size')
     may be allocated in order to avoid disk seeks.

   * All joins are executed in a single pass, and most joins can be
     done without even using a temporary table. Most temporary tables
     are memory-based hash tables. Temporary tables with a large row
     length (calculated as the sum of all column lengths) or that
     contain *Note `BLOB': blob.  columns are stored on disk.

     If an internal heap table exceeds the size of `tmp_table_size',
     MySQL handles this automatically by changing the in-memory heap
     table to a disk-based `MyISAM' table as necessary. You can also
     increase the temporary table size by setting the `tmp_table_size'
     option to *Note `mysqld': mysqld, or by setting the SQL option
     `sql_big_tables' in the client program. See *Note
     server-session-variables::.

     MySQL Enterprise

     Subscribers to the MySQL Enterprise Monitor are alerted when
     temporary tables exceed `tmp_table_size'. Advisors make
     recommendations for the optimum value of `tmp_table_size' based on
     actual table usage. For more information about the MySQL
     Enterprise Monitor please see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   * Most requests that perform a sort allocate a sort buffer and zero
     to two temporary files depending on the result set size. See *Note
     temporary-files::.

   * Almost all parsing and calculating is done in a local memory
     store. No memory overhead is needed for small items, so the normal
     slow memory allocation and freeing is avoided. Memory is allocated
     only for unexpectedly large strings. This is done with `malloc()'
     and `free()'.

   * For each `MyISAM' table that is opened, the index file is opened
     once; the data file is opened once for each concurrently running
     thread. For each concurrent thread, a table structure, column
     structures for each column, and a buffer of size `3 x N' are
     allocated (where N is the maximum row length, not counting *Note
     `BLOB': blob. columns). A *Note `BLOB': blob. column requires five
     to eight bytes plus the length of the *Note `BLOB': blob. data. The
     `MyISAM' storage engine maintains one extra row buffer for
     internal use.

   * For each table having *Note `BLOB': blob.  columns, a buffer is
     enlarged dynamically to read in larger *Note `BLOB': blob. values.
     If you scan a table, a buffer as large as the largest *Note
     `BLOB': blob. value is allocated.

   * Handler structures for all in-use tables are saved in a cache and
     managed as a FIFO. By default, the cache has 64 entries. If a
     table has been used by two running threads at the same time, the
     cache contains two entries for the table.  See *Note table-cache::.

   * A *Note `FLUSH TABLES': flush. statement or *Note `mysqladmin
     flush-tables': mysqladmin. command closes all tables that are not
     in use at once and marks all in-use tables to be closed when the
     currently executing thread finishes. This effectively frees most
     in-use memory.  *Note `FLUSH TABLES': flush. does not return until
     all tables have been closed.

   * The server caches information in memory as a result of *Note
     `GRANT': grant, *Note `CREATE USER': create-user, *Note `CREATE
     SERVER': create-server, and *Note `INSTALL PLUGIN':
     install-plugin. statements.  This memory is not released by the
     corresponding *Note `REVOKE': revoke, *Note `DROP USER': drop-user,
     *Note `DROP SERVER': drop-server, and *Note `UNINSTALL PLUGIN':
     uninstall-plugin. statements, so for a server that executes many
     instances of the statements that cause caching, there will be an
     increase in memory use. This cached memory can be freed with *Note
     `FLUSH PRIVILEGES': flush.

`ps' and other system status programs may report that *Note `mysqld':
mysqld. uses a lot of memory. This may be caused by thread stacks on
different memory addresses.  For example, the Solaris version of `ps'
counts the unused memory between stacks as used memory. You can verify
this by checking available swap with `swap -s'.  We test *Note
`mysqld': mysqld. with several memory-leakage detectors (both
commercial and Open Source), so there should be no memory leaks.


File: manual.info,  Node: large-page-support,  Next: internal-temporary-tables,  Prev: memory-use,  Up: optimizing-the-server

7.5.9 Enabling Large Page Support
---------------------------------

Some hardware/operating system architectures support memory pages
greater than the default (usually 4KB). The actual implementation of
this support depends on the underlying hardware and operating system.
Applications that perform a lot of memory accesses may obtain
performance improvements by using large pages due to reduced
Translation Lookaside Buffer (TLB) misses.

In MySQL, large pages can be used by InnoDB, to allocate memory for its
buffer pool and additional memory pool.

Currently, MySQL supports only the Linux implementation of large page
support (which is called HugeTLB in Linux). Before large pages can be
used on Linux, the kernel must be enabled to support them and it is
necessary to configure the HugeTLB memory pool. For reference, the
HugeTBL API is documented in the `Documentation/vm/hugetlbpage.txt'
file of your Linux sources.

For some recent systems, such as Red Hat Enterprise Linux, the kernel
appears to have the large pages feature enabled by default. To check
whether this is true for your kernel, use the following command and
look for output lines containing `huge':

     shell> cat /proc/meminfo | grep -i huge
     HugePages_Total:       0
     HugePages_Free:        0
     HugePages_Rsvd:        0
     HugePages_Surp:        0
     Hugepagesize:       4096 kB

The non-empty command output indicates that large page support is
present. The zero values indicate that no pages are configured for use.

If the output is empty, your kernel needs to be reconfigured to support
large pages. Consult the `hugetlbpage.txt' file for instructions.

Assuming that your Linux kernel has large page support enabled,
configure it for use by MySQL using the following commands.  Normally,
you put these in an `rc' file or equivalent startup file that is
executed during the system boot sequence, so that the commands execute
each time the system starts. The commands should execute early in the
boot sequence, before the MySQL server starts. Be sure to change the
allocation numbers and the group number as appropriate for your system.

     # Set the number of pages to be used.
     # Each page is normally 2MB, so a value of 20 = 40MB.
     # This command actually allocates memory, so this much
     # memory must be available.
     echo 20 > /proc/sys/vm/nr_hugepages

     # Set the group number that is allowed to access this
     # memory (102 in this case). The mysql user must be a
     # member of this group.
     echo 102 > /proc/sys/vm/hugetlb_shm_group

     # Increase the amount of shmem allowed per segment
     # (12G in this case).
     echo 1560281088 > /proc/sys/kernel/shmmax

     # Increase total amount of shared memory.  The value
     # is the number of pages. At 4KB/page, 4194304 = 16GB.
     echo 4194304 > /proc/sys/kernel/shmall

For MySQL usage, you normally want the value of `shmmax' to be close to
the value of `shmall'.

To verify the large page configuration, check `/proc/meminfo' again as
described previously. Now you should see some non-zero values:

     shell> cat /proc/meminfo | grep -i huge
     HugePages_Total:      20
     HugePages_Free:       20
     HugePages_Rsvd:        0
     HugePages_Surp:        0
     Hugepagesize:       4096 kB

The final step to make use of the `hugetlb_shm_group' is to give the
`mysql' user an `unlimited' value for the memlock limit. This can by
done either by editing `/etc/security/limits.conf' or by adding the
following command to your *Note `mysqld_safe': mysqld-safe. script:

     ulimit -l unlimited

Adding the `ulimit' command to *Note `mysqld_safe': mysqld-safe. causes
the `root' user to set the memlock limit to `unlimited' before
switching to the `mysql' user. (This assumes that *Note `mysqld_safe':
mysqld-safe. is started by `root'.)

Large page support in MySQL is disabled by default. To enable it, start
the server with the `--large-pages' option. For example, you can use
the following lines in your server's `my.cnf' file:

     [mysqld]
     large-pages

With this option, `InnoDB' uses large pages automatically for its
buffer pool and additional memory pool. If `InnoDB' cannot do this, it
falls back to use of traditional memory and writes a warning to the
error log: `Warning: Using conventional memory pool'

You can verify that large pages are being used by checking
`/proc/meminfo' again:

     shell> cat /proc/meminfo | grep -i huge
     HugePages_Total:      20
     HugePages_Free:       20
     HugePages_Rsvd:        2
     HugePages_Surp:        0
     Hugepagesize:       4096 kB


File: manual.info,  Node: internal-temporary-tables,  Next: dns,  Prev: large-page-support,  Up: optimizing-the-server

7.5.10 How MySQL Uses Internal Temporary Tables
-----------------------------------------------

In some cases, the server creates internal temporary tables while
processing queries. A temporary table can be held in memory and
processed by the `MEMORY' storage engine, or stored on disk and
processed by the `MyISAM' storage engine. Temporary tables can be
created under conditions such as these:

   * If there is an `ORDER BY' clause and a different `GROUP BY'
     clause, or if the `ORDER BY' or `GROUP BY' contains columns from
     tables other than the first table in the join queue, a temporary
     table is created.

   * If you use the `SQL_SMALL_RESULT' option, MySQL uses an in-memory
     temporary table.

   * `DISTINCT' combined with `ORDER BY' may require a temporary table.

You can tell whether a query requires a temporary table by using *Note
`EXPLAIN': explain. and checking the `Extra' column to see whether it
says `Using temporary'. See *Note using-explain::.

Some conditions prevent the use of a `MEMORY' temporary table, in which
case the server uses a `MyISAM' table instead:

   * Presence of a *Note `TEXT': blob. or *Note `BLOB': blob. column in
     the table

   * Presence of any column in a `GROUP BY' or `DISTINCT' clause larger
     than 512 bytes

   * Presence of any column larger than 512 bytes in the *Note
     `SELECT': select. list, if *Note `UNION': union. or *Note `UNION
     ALL': union.  is used.

A temporary table that is created initially as a `MEMORY' table might
be converted to a `MyISAM' table and stored on disk if it becomes too
large. The `max_heap_table_size' system variable determines how large
`MEMORY' tables are allowed to grow. It applies to all `MEMORY' tables,
including those created with *Note `CREATE TABLE': create-table.
However, for internal `MEMORY' tables, the actual maximum size is
determined by `max_heap_table_size' in combination with
`tmp_table_size': Whichever value is smaller is the one that applies.
If the size of an internal `MEMORY' table exceeds the limit, MySQL
automatically converts it to an on-disk `MyISAM' table.


File: manual.info,  Node: dns,  Prev: internal-temporary-tables,  Up: optimizing-the-server

7.5.11 How MySQL Uses DNS
-------------------------

When a new client connects to *Note `mysqld': mysqld, *Note `mysqld':
mysqld. spawns a new thread to handle the request. This thread first
checks whether the host name is in the host name cache. If not, the
thread attempts to resolve the host name:

   * The thread takes the IP address and resolves it to a host name
     (using `gethostbyaddr()'). It then takes that host name and
     resolves it back to the IP address (using `gethostbyname()') and
     compares to ensure it is the original IP address.

   * If the operating system supports the thread-safe
     `gethostbyaddr_r()' and `gethostbyname_r()' calls, the thread uses
     them to perform host name resolution.

   * If the operating system does not support the thread-safe calls,
     the thread locks a mutex and calls `gethostbyaddr()' and
     `gethostbyname()' instead. In this case, no other thread can
     resolve host names that are not in the host name cache until the
     first thread unlocks the mutex.

You can disable DNS host name lookups by starting *Note `mysqld':
mysqld. with the `--skip-name-resolve' option.  However, in this case,
you can use only IP numbers in the MySQL grant tables.

If you have a very slow DNS and many hosts, you can get more
performance by either disabling DNS lookups with `--skip-name-resolve'
or by increasing the `HOST_CACHE_SIZE' define (default value: 128) and
recompiling *Note `mysqld': mysqld.

You can disable the host name cache by starting the server with the
`--skip-host-cache' option. To clear the host name cache, issue a *Note
`FLUSH HOSTS': flush.  statement or execute the *Note `mysqladmin
flush-hosts': mysqladmin. command.

To disallow TCP/IP connections entirely, start *Note `mysqld': mysqld.
with the `--skip-networking' option.


File: manual.info,  Node: disk-issues,  Prev: optimizing-the-server,  Up: optimization

7.6 Disk Issues
===============

* Menu:

* symbolic-links::               Using Symbolic Links

   * Disk seeks are a huge performance bottleneck. This problem becomes
     more apparent when the amount of data starts to grow so large that
     effective caching becomes impossible. For large databases where
     you access data more or less randomly, you can be sure that you
     need at least one disk seek to read and a couple of disk seeks to
     write things. To minimize this problem, use disks with low seek
     times.

   * Increase the number of available disk spindles (and thereby reduce
     the seek overhead) by either symlinking files to different disks
     or striping the disks:

        * Using symbolic links

          This means that, for `MyISAM' tables, you symlink the index
          file and data files from their usual location in the data
          directory to another disk (that may also be striped). This
          makes both the seek and read times better, assuming that the
          disk is not used for other purposes as well. See *Note
          symbolic-links::.

        * Striping

          Striping means that you have many disks and put the first
          block on the first disk, the second block on the second disk,
          and the N-th block on the (`N MOD NUMBER_OF_DISKS') disk, and
          so on. This means if your normal data size is less than the
          stripe size (or perfectly aligned), you get much better
          performance. Striping is very dependent on the operating
          system and the stripe size, so benchmark your application
          with different stripe sizes. See *Note custom-benchmarks::.

          The speed difference for striping is _very_ dependent on the
          parameters.  Depending on how you set the striping parameters
          and number of disks, you may get differences measured in
          orders of magnitude. You have to choose to optimize for
          random or sequential access.

   * For reliability, you may want to use RAID 0+1 (striping plus
     mirroring), but in this case, you need 2 x N drives to hold N
     drives of data. This is probably the best option if you have the
     money for it. However, you may also have to invest in some
     volume-management software to handle it efficiently.

   * A good option is to vary the RAID level according to how critical
     a type of data is. For example, store semi-important data that can
     be regenerated on a RAID 0 disk, but store really important data
     such as host information and logs on a RAID 0+1 or RAID N disk.
     RAID N can be a problem if you have many writes, due to the time
     required to update the parity bits.

   * On Linux, you can get much more performance by using `hdparm' to
     configure your disk's interface.  (Up to 100% under load is not
     uncommon.) The following `hdparm' options should be quite good for
     MySQL, and probably for many other applications:

          hdparm -m 16 -d 1

     Note that performance and reliability when using this command
     depend on your hardware, so we strongly suggest that you test your
     system thoroughly after using `hdparm'.  Please consult the
     `hdparm' manual page for more information. If `hdparm' is not used
     wisely, file system corruption may result, so back up everything
     before experimenting!

   * You can also set the parameters for the file system that the
     database uses:

     If you do not need to know when files were last accessed (which is
     not really useful on a database server), you can mount your file
     systems with the `-o noatime' option. That skips updates to the
     last access time in inodes on the file system, which avoids some
     disk seeks.

     On many operating systems, you can set a file system to be updated
     asynchronously by mounting it with the `-o async' option. If your
     computer is reasonably stable, this should give you more
     performance without sacrificing too much reliability. (This flag
     is on by default on Linux.)


File: manual.info,  Node: symbolic-links,  Prev: disk-issues,  Up: disk-issues

7.6.1 Using Symbolic Links
--------------------------

* Menu:

* symbolic-links-to-databases::  Using Symbolic Links for Databases on Unix
* symbolic-links-to-tables::     Using Symbolic Links for Tables on Unix
* windows-symbolic-links::       Using Symbolic Links for Databases on Windows

You can move tables and databases from the database directory to other
locations and replace them with symbolic links to the new locations.
You might want to do this, for example, to move a database to a file
system with more free space or increase the speed of your system by
spreading your tables to different disk.

The recommended way to do this is simply to symlink databases to a
different disk. Symlink tables only as a last resort.


File: manual.info,  Node: symbolic-links-to-databases,  Next: symbolic-links-to-tables,  Prev: symbolic-links,  Up: symbolic-links

7.6.1.1 Using Symbolic Links for Databases on Unix
..................................................

On Unix, the way to symlink a database is first to create a directory
on some disk where you have free space and then to create a symlink to
it from the MySQL data directory.

     shell> mkdir /dr1/databases/test
     shell> ln -s /dr1/databases/test /PATH/TO/DATADIR

MySQL does not support linking one directory to multiple databases.
Replacing a database directory with a symbolic link works as long as
you do not make a symbolic link between databases. Suppose that you
have a database `db1' under the MySQL data directory, and then make a
symlink `db2' that points to `db1':

     shell> cd /PATH/TO/DATADIR
     shell> ln -s db1 db2

The result is that, or any table `tbl_a' in `db1', there also appears
to be a table `tbl_a' in `db2'. If one client updates `db1.tbl_a' and
another client updates `db2.tbl_a', problems are likely to occur.

However, if you really need to do this, it is possible by altering the
source file `mysys/my_symlink.c', in which you should look for the
following statement:

     if (!(MyFlags & MY_RESOLVE_LINK) ||
         (!lstat(filename,&stat_buff) && S_ISLNK(stat_buff.st_mode)))

Change the statement to this:

     if (1)


File: manual.info,  Node: symbolic-links-to-tables,  Next: windows-symbolic-links,  Prev: symbolic-links-to-databases,  Up: symbolic-links

7.6.1.2 Using Symbolic Links for Tables on Unix
...............................................

You should not symlink tables on systems that do not have a fully
operational `realpath()' call. (Linux and Solaris support
`realpath()'). You can check whether your system supports symbolic
links by issuing a `SHOW VARIABLES LIKE 'have_symlink'' statement.

Symlinks are fully supported only for `MyISAM' tables. For files used
by tables for other storage engines, you may get strange problems if
you try to use symbolic links.

The handling of symbolic links for `MyISAM' tables works as follows:

   * In the data directory, you always have the table format (`.frm')
     file, the data (`.MYD') file, and the index (`.MYI') file. The
     data file and index file can be moved elsewhere and replaced in
     the data directory by symlinks. The format file cannot.

   * You can symlink the data file and the index file independently to
     different directories.

   * You can instruct a running MySQL server to perform the symlinking
     by using the `DATA DIRECTORY' and `INDEX DIRECTORY' options to
     *Note `CREATE TABLE': create-table. See *Note create-table::.
     Alternatively, symlinking can be accomplished manually from the
     command line using `ln -s' if *Note `mysqld': mysqld. is not
     running.

     *Note*:

     Beginning with MySQL 6.0.5, the path used with either or both of
     the `DATA DIRECTORY' and `INDEX DIRECTORY' options may not include
     the MySQL `data' directory.  (Bug#32167
     (http://bugs.mysql.com/32167))

   * *Note `myisamchk': myisamchk. does not replace a symlink with the
     data file or index file. It works directly on the file to which
     the symlink points. Any temporary files are created in the
     directory where the data file or index file is located. The same
     is true for the *Note `ALTER TABLE': alter-table, *Note `OPTIMIZE
     TABLE': optimize-table, and *Note `REPAIR TABLE': repair-table.
     statements.

   * *Note*:

     When you drop a table that is using symlinks, _both the symlink
     and the file to which the symlink points are dropped_. This is an
     extremely good reason why you should _not_ run *Note `mysqld':
     mysqld.  as the system `root' or allow system users to have write
     access to MySQL database directories.

   * If you rename a table with `ALTER TABLE ...  RENAME' or *Note
     `RENAME TABLE': rename-table. and you do not move the table to
     another database, the symlinks in the database directory are
     renamed to the new names and the data file and index file are
     renamed accordingly.

   * If you use `ALTER TABLE ... RENAME' or *Note `RENAME TABLE':
     rename-table. to move a table to another database, the table is
     moved to the other database directory. If the table name changed,
     the symlinks in the new database directory are renamed to the new
     names and the data file and index file are renamed accordingly.

   * If you are not using symlinks, you should use the
     `--skip-symbolic-links' option to *Note `mysqld': mysqld. to
     ensure that no one can use *Note `mysqld': mysqld. to drop or
     rename a file outside of the data directory.

Table symlink operations that are not yet supported:

   * *Note `ALTER TABLE': alter-table. ignores the `DATA DIRECTORY' and
     `INDEX DIRECTORY' table options.

   * The `.frm' file must _never_ be a symbolic link (as indicated
     previously, only the data and index files can be symbolic links).
     Attempting to do this (for example, to make synonyms) produces
     incorrect results. Suppose that you have a database `db1' under
     the MySQL data directory, a table `tbl1' in this database, and in
     the `db1' directory you make a symlink `tbl2' that points to
     `tbl1':

          shell> cd /PATH/TO/DATADIR/db1
          shell> ln -s tbl1.frm tbl2.frm
          shell> ln -s tbl1.MYD tbl2.MYD
          shell> ln -s tbl1.MYI tbl2.MYI

     Problems result if one thread reads `db1.tbl1' and another thread
     updates `db1.tbl2':

        * The query cache is `fooled' (it has no way of knowing that
          `tbl1' has not been updated, so it returns outdated results).

        * `ALTER' statements on `tbl2' fail.


File: manual.info,  Node: windows-symbolic-links,  Prev: symbolic-links-to-tables,  Up: symbolic-links

7.6.1.3 Using Symbolic Links for Databases on Windows
.....................................................

Symbolic links are enabled by default for all Windows servers.  This
enables you to put a database directory on a different disk by setting
up a symbolic link to it. This is similar to the way that database
symbolic links work on Unix, although the procedure for setting up the
link is different. If you do not need symbolic links, you can disable
them using the `--skip-symbolic-links' option.

On Windows, create a symbolic link to a MySQL database by creating a
file in the data directory that contains the path to the destination
directory. The file should be named `DB_NAME.sym', where DB_NAME is the
database name.

Suppose that the MySQL data directory is `C:\mysql\data' and you want
to have database `foo' located at `D:\data\foo'. Set up a symlink using
this procedure

  1. Make sure that the `D:\data\foo' directory exists by creating it
     if necessary. If you already have a database directory named `foo'
     in the data directory, you should move it to `D:\data'. Otherwise,
     the symbolic link will be ineffective. To avoid problems, make
     sure that the server is not running when you move the database
     directory.

  2. Create a text file `C:\mysql\data\foo.sym' that contains the path
     name `D:\data\foo\'.

     *Note*:

     The path name to the new database and tables should be absolute.
     If you specify a relative path, the location will be relative to
     the `foo.sym' file.

After this, all tables created in the database `foo' are created in
`D:\data\foo'.

The following limitations apply to the use of `.sym' files for database
symbolic linking on Windows:

   * The symbolic link is not used if a directory with the same name as
     the database exists in the MySQL data directory.

   * The `--innodb_file_per_table' option cannot be used.

   * If you run *Note `mysqld': mysqld. as a service, you cannot use a
     mapped drive to a remote server as the destination of the symbolic
     link. As a workaround, you can use the full path
     (`\\servername\path\').


File: manual.info,  Node: language-structure,  Next: internationalization-localization,  Prev: optimization,  Up: Top

8 Language Structure
********************

* Menu:

* literals::                     Literal Values
* identifiers::                  Schema Object Names
* reserved-words::               Reserved Words
* user-variables::               User-Defined Variables
* comments::                     Comment Syntax

This chapter discusses the rules for writing the following elements of
SQL statements when using MySQL:

   * Literal values such as strings and numbers

   * Identifiers such as database, table, and column names

   * Reserved words

   * User-defined and system variables

   * Comments


File: manual.info,  Node: literals,  Next: identifiers,  Prev: language-structure,  Up: language-structure

8.1 Literal Values
==================

* Menu:

* string-syntax::                Strings
* number-syntax::                Numbers
* hexadecimal-values::           Hexadecimal Values
* boolean-values::               Boolean Values
* bit-field-values::             Bit-Field Values
* null-values::                  `NULL' Values

This section describes how to write literal values in MySQL. These
include strings, numbers, hexadecimal values, boolean values, and
`NULL'. The section also covers the various nuances and `gotchas' that
you may run into when dealing with these basic types in MySQL.


File: manual.info,  Node: string-syntax,  Next: number-syntax,  Prev: literals,  Up: literals

8.1.1 Strings
-------------

A string is a sequence of bytes or characters, enclosed within either
single quote (``''') or double quote (``"'') characters.  Examples:

     'a string'
     "another string"

Quoted strings placed next to each other are concatenated to a single
string. The following lines are equivalent:

     'a string'
     'a' ' ' 'string'

If the `ANSI_QUOTES' SQL mode is enabled, string literals can be quoted
only within single quotes because a string quoted within double quotes
is interpreted as an identifier.

A _binary string_ is a string of bytes that has no character set or
collation. A _non-binary string_ is a string of characters that has a
character set and collation. For both types of strings, comparisons are
based on the numeric values of the string unit.  For binary strings,
the unit is the byte. For non-binary strings the unit is the character
and some character sets allow multi-byte characters. Character value
ordering is a function of the string collation.

String literals may have an optional character set introducer and
`COLLATE' clause:

     [_CHARSET_NAME]'STRING' [COLLATE COLLATION_NAME]

Examples:

     SELECT _latin1'STRING';
     SELECT _latin1'STRING' COLLATE latin1_danish_ci;

You can use `N'LITERAL'' (or `n'LITERAL'') to create a string in the
national character set. These statements are equivalent:

     SELECT N'some text';
     SELECT n'some text';
     SELECT _utf8'some text';

For more information about these forms of string syntax, see *Note
charset-literal::, and *Note charset-national::.

Within a string, certain sequences have special meaning unless the
`NO_BACKSLASH_ESCAPES' SQL mode is enabled. Each of these sequences
begins with a backslash (``\''), known as the _escape character_. MySQL
recognizes the following escape sequences.

`\0'    An ASCII NUL (`0x00') character.
`\''    A single quote (``''') character.
`\"'    A double quote (``"'') character.
`\b'    A backspace character.
`\n'    A newline (linefeed) character.
`\r'    A carriage return character.
`\t'    A tab character.
`\Z'    ASCII 26 (Control-Z). See note following the table.
`\\'    A backslash (``\'') character.
`\%'    A ``%'' character. See note following the table.
`\_'    A ``_'' character. See note following the table.

For all other escape sequences, backslash is ignored. That is, the
escaped character is interpreted as if it was not escaped.  For
example, ``\x'' is just ``x''.

These sequences are case sensitive. For example, ``\b'' is interpreted
as a backspace, but ``\B'' is interpreted as ``B''.

The ASCII 26 character can be encoded as ``\Z'' to enable you to work
around the problem that ASCII 26 stands for END-OF-FILE on Windows.
ASCII 26 within a file causes problems if you try to use `mysql DB_NAME
< FILE_NAME'.

Escape processing is done according to the character set indicated by
the `character_set_connection' system variable. This is true even for
strings that are preceded by an introducer that indicates a different
character set, as discussed in *Note charset-literal::.

The ``\%'' and ``\_'' sequences are used to search for literal
instances of ``%'' and ``_'' in pattern-matching contexts where they
would otherwise be interpreted as wildcard characters. See the
description of the `LIKE' operator in *Note
string-comparison-functions::. If you use ``\%'' or ``\_'' in
non-pattern-matching contexts, they evaluate to the strings ``\%'' and
``\_'', not to ``%'' and ``_''.

There are several ways to include quote characters within a string:

   * A ``''' inside a string quoted with ``''' may be written as ``''''.

   * A ``"'' inside a string quoted with ``"'' may be written as ``""''.

   * Precede the quote character by an escape character (``\'').

   * A ``''' inside a string quoted with ``"'' needs no special
     treatment and need not be doubled or escaped. In the same way,
     ``"'' inside a string quoted with ``''' needs no special treatment.

The following *Note `SELECT': select. statements demonstrate how
quoting and escaping work:

     mysql> SELECT 'hello', '"hello"', '""hello""', 'hel''lo', '\'hello';
     +-------+---------+-----------+--------+--------+
     | hello | "hello" | ""hello"" | hel'lo | 'hello |
     +-------+---------+-----------+--------+--------+

     mysql> SELECT "hello", "'hello'", "''hello''", "hel""lo", "\"hello";
     +-------+---------+-----------+--------+--------+
     | hello | 'hello' | ''hello'' | hel"lo | "hello |
     +-------+---------+-----------+--------+--------+

     mysql> SELECT 'This\nIs\nFour\nLines';
     +--------------------+
     | This
     Is
     Four
     Lines |
     +--------------------+

     mysql> SELECT 'disappearing\ backslash';
     +------------------------+
     | disappearing backslash |
     +------------------------+

If you want to insert binary data into a string column (such as a *Note
`BLOB': blob. column), the following characters must be represented by
escape sequences.

`NUL'   `NUL' byte (`0x00'). Represent this character by ``\0'' (a
        backslash followed by an ASCII ``0'' character).
`\'     Backslash (ASCII 92). Represent this character by ``\\''.
`''     Single quote (ASCII 39). Represent this character by ``\'''.
`"'     Double quote (ASCII 34). Represent this character by ``\"''.

When writing application programs, any string that might contain any of
these special characters must be properly escaped before the string is
used as a data value in an SQL statement that is sent to the MySQL
server. You can do this in two ways:

   * Process the string with a function that escapes the special
     characters. In a C program, you can use the *Note
     `mysql_real_escape_string()': mysql-real-escape-string. C API
     function to escape characters. See *Note
     mysql-real-escape-string::. The Perl DBI interface provides a
     `quote' method to convert special characters to the proper escape
     sequences.  See *Note apis-perl::. Other language interfaces may
     provide a similar capability.

   * As an alternative to explicitly escaping special characters, many
     MySQL APIs provide a placeholder capability that enables you to
     insert special markers into a statement string, and then bind data
     values to them when you issue the statement. In this case, the API
     takes care of escaping special characters in the values for you.


File: manual.info,  Node: number-syntax,  Next: hexadecimal-values,  Prev: string-syntax,  Up: literals

8.1.2 Numbers
-------------

Integers are represented as a sequence of digits. Floats use ``.'' as a
decimal separator.  Either type of number may be preceded by ``-'' or
``+'' to indicate a negative or positive value, respectively

Examples of valid integers:

     1221
     0
     -32

Examples of valid floating-point numbers:

     294.42
     -32032.6809e+10
     148.00

An integer may be used in a floating-point context; it is interpreted
as the equivalent floating-point number.


File: manual.info,  Node: hexadecimal-values,  Next: boolean-values,  Prev: number-syntax,  Up: literals

8.1.3 Hexadecimal Values
------------------------

MySQL supports hexadecimal values, written using `X'VAL'', `x'VAL'', or
`0xVAL' format, where VAL contains hexadecimal digits (`0..9', `A..F').
Lettercase of the digits does not matter. For values written using
`X'VAL'' or `x'VAL'' format, VAL must contain an even number of digits.
For values written using `0xVAL syntax', values that contain an odd
number of digits are treated as having an extra leading `0'. For
example, `0x0a' and `0xaaa' are interpreted as `0x0a' and `0x0aaa'.

In numeric contexts, hexadecimal values act like integers (64-bit
precision). In string contexts, they act like binary strings, where
each pair of hex digits is converted to a character:

     mysql> SELECT X'4D7953514C';
             -> 'MySQL'
     mysql> SELECT 0x0a+0;
             -> 10
     mysql> SELECT 0x5061756c;
             -> 'Paul'

The default type of a hexadecimal value is a string. If you want to
ensure that the value is treated as a number, you can use `CAST(... AS
UNSIGNED)':

     mysql> SELECT 0x41, CAST(0x41 AS UNSIGNED);
             -> 'A', 65

The `X'HEXSTRING'' syntax is based on standard SQL. The `0x' syntax is
based on ODBC. Hexadecimal strings are often used by ODBC to supply
values for *Note `BLOB': blob.  columns.

You can convert a string or a number to a string in hexadecimal format
with the `HEX()' function:

     mysql> SELECT HEX('cat');
             -> '636174'
     mysql> SELECT 0x636174;
             -> 'cat'


File: manual.info,  Node: boolean-values,  Next: bit-field-values,  Prev: hexadecimal-values,  Up: literals

8.1.4 Boolean Values
--------------------

The constants `TRUE' and `FALSE' evaluate to `1' and `0', respectively.
The constant names can be written in any lettercase.

     mysql> SELECT TRUE, true, FALSE, false;
             -> 1, 1, 0, 0


File: manual.info,  Node: bit-field-values,  Next: null-values,  Prev: boolean-values,  Up: literals

8.1.5 Bit-Field Values
----------------------

Bit-field values can be written using `b'VALUE'' or `0bVALUE' notation.
VALUE is a binary value written using zeros and ones.

Bit-field notation is convenient for specifying values to be assigned
to *Note `BIT': numeric-types. columns:

     mysql> CREATE TABLE t (b BIT(8));
     mysql> INSERT INTO t SET b = b'11111111';
     mysql> INSERT INTO t SET b = b'1010';
     mysql> INSERT INTO t SET b = b'0101';

Bit values are returned as binary values. To display them in printable
form, add 0 or use a conversion function such as `BIN()'. High-order 0
bits are not displayed in the converted value.

     mysql> SELECT b+0, BIN(b+0), OCT(b+0), HEX(b+0) FROM t;
     +------+----------+----------+----------+
     | b+0  | BIN(b+0) | OCT(b+0) | HEX(b+0) |
     +------+----------+----------+----------+
     |  255 | 11111111 | 377      | FF       |
     |   10 | 1010     | 12       | A        |
     |    5 | 101      | 5        | 5        |
     +------+----------+----------+----------+

Bit values assigned to user variables are treated as binary strings. To
assign a bit value as a number to a user variable, use `CAST()' or `+0':

     mysql> SET @v1 = 0b1000001;
     mysql> SET @v2 = CAST(0b1000001 AS UNSIGNED), @v3 = 0b1000001+0;
     mysql> SELECT @v1, @v2, @v3;
     +------+------+------+
     | @v1  | @v2  | @v3  |
     +------+------+------+
     | A    |   65 |   65 |
     +------+------+------+


File: manual.info,  Node: null-values,  Prev: bit-field-values,  Up: literals

8.1.6 `NULL' Values
-------------------

The `NULL' value means `no data.' `NULL' can be written in any
lettercase. A synonym is `\N' (case sensitive).

For text file import or export operations performed with *Note `LOAD
DATA INFILE': load-data. or *Note `SELECT ... INTO OUTFILE': select,
`NULL' is represented by the `\N' sequence. See *Note load-data::.

Be aware that the `NULL' value is different from values such as `0' for
numeric types or the empty string for string types. For more
information, see *Note problems-with-null::.


File: manual.info,  Node: identifiers,  Next: reserved-words,  Prev: literals,  Up: language-structure

8.2 Schema Object Names
=======================

* Menu:

* identifier-qualifiers::        Identifier Qualifiers
* identifier-case-sensitivity::  Identifier Case Sensitivity
* identifier-mapping::           Mapping of Identifiers to File Names
* function-resolution::          Function Name Parsing and Resolution

Certain objects within MySQL, including database, table, index, column,
alias, view, stored procedure, partition, tablespace, and other object
names are known as identifiers. This section describes the allowable
syntax for identifiers in MySQL.  *Note identifier-case-sensitivity::,
describes which types of identifiers are case sensitive and under what
conditions.

An identifier may be quoted or unquoted. If an identifier contains
special characters or is a reserved word, you _must_ quote it whenever
you refer to it. The set of alphanumeric characters from the current
character set, ``_'', and ``$'' are not special. Reserved words are
listed at *Note reserved-words::. (Exception: A reserved word that
follows a period in a qualified name must be an identifier, so it need
not be quoted.)

The identifier quote character is the backtick (```''):

     mysql> SELECT * FROM `select` WHERE `select`.id > 100;

If the `ANSI_QUOTES' SQL mode is enabled, it is also allowable to quote
identifiers within double quotes:

     mysql> CREATE TABLE "test" (col INT);
     ERROR 1064: You have an error in your SQL syntax...
     mysql> SET sql_mode='ANSI_QUOTES';
     mysql> CREATE TABLE "test" (col INT);
     Query OK, 0 rows affected (0.00 sec)

The `ANSI_QUOTES' mode causes the server to interpret double-quoted
strings as identifiers.  Consequently, when this mode is enabled,
string literals must be enclosed within single quotes. They cannot be
enclosed within double quotes. The server SQL mode is controlled as
described in *Note server-sql-mode::.

Identifier quote characters can be included within an identifier if you
quote the identifier. If the character to be included within the
identifier is the same as that used to quote the identifier itself,
then you need to double the character. The following statement creates
a table named `a`b' that contains a column named `c"d':

     mysql> CREATE TABLE `a``b` (`c"d` INT);

Aliases may be quoted either as identifiers or as strings:

     mysql> SELECT 1 AS `one`, 2 AS 'two';
     +-----+-----+
     | one | two |
     +-----+-----+
     |   1 |   2 |
     +-----+-----+

Identifiers may begin with a digit but unless quoted may not consist
solely of digits.

It is recommended that you do not use names of the form `Me' or `MeN',
where M and N are integers. For example, avoid using `1e' or `2e2' as
identifiers, because an expression such as `1e+3' is ambiguous.
Depending on context, it might be interpreted as the expression `1e +
3' or as the number `1e+3'.

Be careful when using `MD5()' to produce table names because it can
produce names in illegal or ambiguous formats such as those just
described.

A user variable cannot be used directly in an SQL statement as an
identifier or as part of an identifier. See *Note user-variables::, for
more information and examples of workarounds.

There are some restrictions on the characters that may appear in
identifiers:

   * No identifier can contain ASCII NUL (`0x00').

   * Database, table, and column names should not end with space
     characters.

Special characters in database and table names are encoded in the
corresponding file system names as described in *Note
identifier-mapping::. If you have databases or tables from an older
version of MySQL that contain special characters and for which the
underlying directory names or file names have not been updated to use
the new encoding, the server displays their names with a prefix of
`#mysql50#'. For information about referring to such names or
converting them to the newer encoding, see that section.

The following table describes the maximum length for each type of
identifier.

*Identifier**Maximum
            Length
            (characters)*
Database    64
Table       64
Column      64
Index       64
Constraint  64
Stored      64
Function    
or          
Procedure   
Trigger     64
View        64
Event       64
Tablespace  64
Server      64
Log File    64
Group       
Alias       256

Identifiers are stored using Unicode (UTF-8). This applies to
identifiers in table definitions that are stored in `.frm' files and to
identifiers stored in the grant tables in the `mysql' database. The
sizes of the identifier string columns in the grant tables are measured
in characters. You can use multi-byte characters without reducing the
number of characters allowed for values stored in these columns,
something not true prior to MySQL 4.1. The allowable Unicode characters
are those in the Basic Multilingual Plane (BMP). Supplementary
characters are not allowed.


File: manual.info,  Node: identifier-qualifiers,  Next: identifier-case-sensitivity,  Prev: identifiers,  Up: identifiers

8.2.1 Identifier Qualifiers
---------------------------

MySQL allows names that consist of a single identifier or multiple
identifiers. The components of a multiple-part name must be separated
by period (``.'') characters. The initial parts of a multiple-part name
act as qualifiers that affect the context within which the final
identifier is interpreted.

In MySQL, you can refer to a table column using any of the following
forms.

*Column Reference*     *Meaning*
COL_NAME               The column COL_NAME from whichever table used in
                       the statement contains a column of that name.
TBL_NAME.COL_NAME      The column COL_NAME from table TBL_NAME of the
                       default database.
DB_NAME.TBL_NAME.COL_NAMEThe column COL_NAME from table TBL_NAME of the
                       database DB_NAME.

If any components of a multiple-part name require quoting, quote them
individually rather than quoting the name as a whole. For example,
write ``my-table`.`my-column`', not ``my-table.my-column`'.

A reserved word that follows a period in a qualified name must be an
identifier, so in that context it need not be quoted.

You need not specify a TBL_NAME or DB_NAME.TBL_NAME prefix for a column
reference in a statement unless the reference would be ambiguous.
Suppose that tables `t1' and `t2' each contain a column `c', and you
retrieve `c' in a *Note `SELECT': select. statement that uses both `t1'
and `t2'. In this case, `c' is ambiguous because it is not unique among
the tables used in the statement. You must qualify it with a table name
as `t1.c' or `t2.c' to indicate which table you mean. Similarly, to
retrieve from a table `t' in database `db1' and from a table `t' in
database `db2' in the same statement, you must refer to columns in
those tables as `db1.t.COL_NAME' and `db2.t.COL_NAME'.

The syntax `.TBL_NAME' means the table TBL_NAME in the default
database. This syntax is accepted for ODBC compatibility because some
ODBC programs prefix table names with a ``.'' character.


File: manual.info,  Node: identifier-case-sensitivity,  Next: identifier-mapping,  Prev: identifier-qualifiers,  Up: identifiers

8.2.2 Identifier Case Sensitivity
---------------------------------

In MySQL, databases correspond to directories within the data
directory. Each table within a database corresponds to at least one
file within the database directory (and possibly more, depending on the
storage engine). Triggers also correspond to files. Consequently, the
case sensitivity of the underlying operating system plays a part in the
case sensitivity of database and table names. This means database,
table, and trigger names are not case sensitive in Windows, but are case
sensitive in most varieties of Unix. One notable exception is Mac OS X,
which is Unix-based but uses a default file system type (HFS+) that is
not case sensitive. However, Mac OS X also supports UFS volumes, which
are case sensitive just as on any Unix. See *Note extensions-to-ansi::.
The `lower_case_table_names' system variable also affects how the
server handles identifier case sensitivity, as described later in this
section.

MySQL Enterprise

`lower_case_table_names' is just one of the system variables monitored
by the MySQL Enterprise Monitor. For information about subscribing to
this service, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Note*:

Although database, table, and trigger names are not case sensitive on
some platforms, you should not refer to one of these using different
cases within the same statement. The following statement would not work
because it refers to a table both as `my_table' and as `MY_TABLE':

     mysql> SELECT * FROM my_table WHERE MY_TABLE.col=1;

Column, index, stored routine, and event names are not case sensitive
on any platform, nor are column aliases.

However, names of triggers and logfile groups are case sensitive. This
differs from standard SQL.

By default, table aliases are case sensitive on Unix, but not so on
Windows or Mac OS X. The following statement would not work on Unix,
because it refers to the alias both as `a' and as `A':

     mysql> SELECT COL_NAME FROM TBL_NAME AS a
         -> WHERE a.COL_NAME = 1 OR A.COL_NAME = 2;

However, this same statement is permitted on Windows. To avoid problems
caused by such differences, it is best to adopt a consistent
convention, such as always creating and referring to databases and
tables using lowercase names. This convention is recommended for
maximum portability and ease of use.

How table and database names are stored on disk and used in MySQL is
affected by the `lower_case_table_names' system variable, which you can
set when starting *Note `mysqld': mysqld.  `lower_case_table_names' can
take the values shown in the following table. This variable does _not_
affect case sensitivity of trigger identifiers. On Unix, the default
value of `lower_case_table_names' is 0. On Windows the default value is
1. On Mac OS X, the default value is 2.

*Value* *Meaning*
`0'     Table and database names are stored on disk using the lettercase
        specified in the *Note `CREATE TABLE': create-table. or *Note
        `CREATE DATABASE': create-database. statement. Name comparisons
        are case sensitive. Note that if you force this variable to 0
        with `--lower-case-table-names=0' on a case-insensitive file
        system and access `MyISAM' tablenames using different
        lettercases, index corruption may result.
`1'     Table names are stored in lowercase on disk and name comparisons
        are not case sensitive. MySQL converts all table names to
        lowercase on storage and lookup. This behavior also applies to
        database names and table aliases.
`2'     Table and database names are stored on disk using the lettercase
        specified in the *Note `CREATE TABLE': create-table. or *Note
        `CREATE DATABASE': create-database. statement, but MySQL
        converts them to lowercase on lookup. Name comparisons are not
        case sensitive. This works _only_ on file systems that are not
        case sensitive!  `InnoDB' table names are stored in lowercase,
        as for `lower_case_table_names=1'.

If you are using MySQL on only one platform, you do not normally have
to change the `lower_case_table_names' variable from its default value.
However, you may encounter difficulties if you want to transfer tables
between platforms that differ in file system case sensitivity. For
example, on Unix, you can have two different tables named `my_table' and
`MY_TABLE', but on Windows these two names are considered identical. To
avoid data transfer problems arising from lettercase of database or
table names, you have two options:

   * Use `lower_case_table_names=1' on all systems. The main
     disadvantage with this is that when you use *Note `SHOW TABLES':
     show-tables. or *Note `SHOW DATABASES': show-databases, you do not
     see the names in their original lettercase.

   * Use `lower_case_table_names=0' on Unix and
     `lower_case_table_names=2' on Windows. This preserves the
     lettercase of database and table names. The disadvantage of this
     is that you must ensure that your statements always refer to your
     database and table names with the correct lettercase on Windows.
     If you transfer your statements to Unix, where lettercase is
     significant, they do not work if the lettercase is incorrect.

     *Exception*: If you are using `InnoDB' tables and you are trying
     to avoid these data transfer problems, you should set
     `lower_case_table_names' to 1 on all platforms to force names to
     be converted to lowercase.

If you plan to set the `lower_case_table_names' system variable to 1 on
Unix, you must first convert your old database and table names to
lowercase before stopping *Note `mysqld': mysqld. and restarting it
with the new variable setting.

Object names may be considered duplicates if their uppercase forms are
equal according to a binary collation. That is true for names of
cursors, conditions, functions, procedures, savepoints, stored routine
parameters, stored program local variables, and plugins. It is not true
for names of columns, constraints, databases, partitions, statements
prepared with *Note `PREPARE': prepare, tables, triggers, users, and
user-defined variables.


File: manual.info,  Node: identifier-mapping,  Next: function-resolution,  Prev: identifier-case-sensitivity,  Up: identifiers

8.2.3 Mapping of Identifiers to File Names
------------------------------------------

There is a correspondence between database and table identifiers and
names in the file system. For the basic structure, MySQL represents
each database as a directory in the data directory, and each table by
one or more files in the appropriate database directory. For the table
format files (`.FRM'), the data is always stored in this structure and
location.

For the data and index files, the exact representation on disk is
storage engine specific. These files may be stored in the same location
as the `FRM' files, or the information may be stored separate file.
`InnoDB' data is stored in the InnoDB data files, and `Falcon' stores
information for a single database within a single file (one file for
each database). If you are using tablespaces with `Falcon' or `InnoDB',
then the specific tablespace files you create are used instead.

Any character is legal in database or table identifiers except ASCII
NUL (`0x00'). MySQL encodes any characters that are problematic in the
corresponding file system objects when it creates database directories
or table files:

   * Basic Latin letters (`a..zA..Z') and digits (`0..9') are encoded
     as is. Consequently, their case sensitivity directly depends on
     file system features.

   * All other national letters from alphabets that have
     uppercase/lowercase mapping are encoded as follows:

          Code range Pattern            Number   Used Unused  Blocks
          -----------------------------------------------------------------------------
          00C0..017F [@][0..4][g..z] 5*20= 100   97     3  Latin1 Supplement + Ext A
          0370..03FF [@][5..9][g..z] 5*20= 100   88    12  Greek + Coptic
          0400..052F [@][g..z][0..6] 20*7= 140  140   137  Cyrillic
          0530..058F [@][g..z][7..8] 20*2=  40   38     2  Armenian
          2160..217F [@][g..z][9]    20*1=  20   16     4  Number Forms
          0180..02AF [@][g..z][a..k] 28*11=220  203    17  Latin Ext B + IPA
          1E00..0EFF [@][g..z][l..r] 20*7= 140  136     4  Latin Additional Extended
          1F00..1FFF [@][g..z][s..z] 20*8= 160  144    16  Greek Extended
          ....  .... [@][a..f][g..z] 6*20= 120    0   120  RESERVED
          24B6..24E9 [@][@][a..z]           26   26     0  Enclosed Alphanumerics
          FF21..FF5A [@][a..z][@]           26   26     0  Full Width forms

     One of the bytes in the sequence encodes lettercase. For example:
     `LATIN CAPITAL LETTER A WITH GRAVE' is encoded as `@0G', whereas
     `LATIN SMALL LETTER A WITH GRAVE' is encoded as `@0g'. Here the
     third byte (`G' or `g') indicates lettercase. (On a
     case-insensitive file system, both letters will be treated as the
     same.)

     For some blocks, such as Cyrillic, the second byte determines
     lettercase. For other blocks, such as Latin1 Supplement, the third
     byte determines lettercase. If two bytes in the sequence are
     letters (as in Greek Extended), the leftmost letter character
     stands for lettercase. All other letter bytes must be in lowercase.

   * All non-letter characters, as well as letters from alphabets that
     do not have uppercase/lowercase mapping (such as Hebrew) are
     encoded using hexadecimal representation using lowercase letters
     for hex digits `a..f':

          0x003F -> @003f
          0xFFFF -> @ffff

     The hexadecimal values correspond to character values in the
     `ucs2' double-byte character set.

On Windows, some names such as `nul', `prn', and `aux' are encoded by
appending `@@@' to the name when the server creates the corresponding
file or directory. This occurs on all platforms for portability of the
corresponding database object between platforms.

If you have databases or tables from a version of MySQL older than
5.1.6 that contain special characters and for which the underlying
directory names or file names have not been updated to use the new
encoding, the server displays their names with a prefix of `#mysql50#'
in the output from `INFORMATION_SCHEMA' tables or *Note `SHOW': show.
statements. For example, if you have a table named `a@b' and its name
encoding has not been updated, *Note `SHOW TABLES': show-tables.
displays it like this:

     mysql> SHOW TABLES;
     +----------------+
     | Tables_in_test |
     +----------------+
     | #mysql50#a@b   |
     +----------------+

To refer to such a name for which the encoding has not been updated,
you must supply the `#mysql50#' prefix:

     mysql> SHOW COLUMNS FROM `a@b`;
     ERROR 1146 (42S02): Table 'test.a@b' doesn't exist

     mysql> SHOW COLUMNS FROM `#mysql50#a@b`;
     +-------+---------+------+-----+---------+-------+
     | Field | Type    | Null | Key | Default | Extra |
     +-------+---------+------+-----+---------+-------+
     | i     | int(11) | YES  |     | NULL    |       |
     +-------+---------+------+-----+---------+-------+

To update old names to eliminate the need to use the special prefix to
refer to them, re-encode them with *Note `mysqlcheck': mysqlcheck. The
following command updates all names to the new encoding:

     shell> mysqlcheck --check-upgrade --fix-db-names --fix-table-names --all-databases

To check only specific databases or tables, omit `--all-databases' and
provide the appropriate database or table arguments. For information
about *Note `mysqlcheck': mysqlcheck. invocation syntax, see *Note
mysqlcheck::.

*Note*:

The `#mysql50#' prefix is intended only to be used internally by the
server. You should not create databases or tables with names that use
this prefix.

Also, *Note `mysqlcheck': mysqlcheck. cannot fix names that contain
literal instances of the `@' character that is used for encoding
special characters. If you have databases or tables that contain this
character, use *Note `mysqldump': mysqldump. to dump them before
upgrading to MySQL 5.1.6 or later, and then reload the dump file after
upgrading.


File: manual.info,  Node: function-resolution,  Prev: identifier-mapping,  Up: identifiers

8.2.4 Function Name Parsing and Resolution
------------------------------------------

MySQL 6.0 supports built-in (native) functions, user-defined functions
(UDFs), and stored functions. This section describes how the server
recognizes whether the name of a built-in function is used as a
function call or as an identifier, and how the server determines which
function to use in cases when functions of different types exist with a
given name.

*Built-In Function Name Parsing*

The parser uses default rules for parsing names of built-in functions.
These rules can be changed by enabling the `IGNORE_SPACE' SQL mode.

When the parser encounters a word that is the name of a built-in
function, it must determine whether the name signifies a function call
or is instead a non-expression reference to an identifier such as a
table or column name. For example, in the following statements, the
first reference to `count' is a function call, whereas the second
reference is a table name:

     SELECT COUNT(*) FROM mytable;
     CREATE TABLE count (i INT);

The parser should recognize the name of a built-in function as
indicating a function call only when parsing what is expected to be an
expression. That is, in non-expression context, function names are
permitted as identifiers.

However, some built-in functions have special parsing or implementation
considerations, so the parser uses the following rules by default to
distinguish whether their names are being used as function calls or as
identifiers in non-expression context:

   * To use the name as a function call in an expression, there must be
     no whitespace between the name and the following ``('' parenthesis
     character.

   * Conversely, to use the function name as an identifier, it must not
     be followed immediately by a parenthesis.

The requirement that function calls be written with no whitespace
between the name and the parenthesis applies only to the built-in
functions that have special considerations.  `COUNT' is one such name.
The exact list of function names for which following whitespace
determines their interpretation are those listed in the
`sql_functions[]' array of the `sql/lex.h' source file. Before MySQL
5.1, these names are rather numerous (about 200), so you may find it
easiest to treat the no-whitespace requirement as applying to all
function calls. In MySQL 5.1 and later, parser improvements reduce to
about 30 the number of affected function names.

For functions not listed in the `sql_functions[]') array, whitespace
does not matter. They are interpreted as function calls only when used
in expression context and may be used freely as identifiers otherwise.
`ASCII' is one such name. However, for these non-affected function
names, interpretation may vary in expression context: `FUNC_NAME ()' is
interpreted as a built-in function if there is one with the given name;
if not, `FUNC_NAME ()' is interpreted as a user-defined function or
stored function if one exists with that name.

The `IGNORE_SPACE' SQL mode can be used to modify how the parser treats
function names that are whitespace-sensitive:

   * With `IGNORE_SPACE' disabled, the parser interprets the name as a
     function call when there is no whitespace between the name and the
     following parenthesis. This occurs even when the function name is
     used in non-expression context:

          mysql> CREATE TABLE count(i INT);
          ERROR 1064 (42000): You have an error in your SQL syntax ...
          near 'count(i INT)'

     To eliminate the error and cause the name to be treated as an
     identifier, either use whitespace following the name or write it
     as a quoted identifier (or both):

          CREATE TABLE count (i INT);
          CREATE TABLE `count`(i INT);
          CREATE TABLE `count` (i INT);

   * With `IGNORE_SPACE' enabled, the parser loosens the requirement
     that there be no whitespace between the function name and the
     following parenthesis. This provides more flexibility in writing
     function calls. For example, either of the following function
     calls are legal:

          SELECT COUNT(*) FROM mytable;
          SELECT COUNT (*) FROM mytable;

     However, enabling `IGNORE_SPACE' also has the side effect that the
     parser treats the affected function names as reserved words (see
     *Note reserved-words::). This means that a space following the
     name no longer signifies its use as an identifier. The name can be
     used in function calls with or without following whitespace, but
     causes a syntax error in non-expression context unless it is
     quoted. For example, with `IGNORE_SPACE' enabled, both of the
     following statements fail with a syntax error because the parser
     interprets `count' as a reserved word:

          CREATE TABLE count(i INT);
          CREATE TABLE count (i INT);

     To use the function name in non-expression context, write it as a
     quoted identifier:

          CREATE TABLE `count`(i INT);
          CREATE TABLE `count` (i INT);

To enable the `IGNORE_SPACE' SQL mode, use this statement:

     SET sql_mode = 'IGNORE_SPACE';

`IGNORE_SPACE' is also enabled by certain other composite modes such as
`ANSI' that include it in their value:

     SET sql_mode = 'ANSI';

Check *Note server-sql-mode::, to see which composite modes enable
`IGNORE_SPACE'.

To minimize the dependency of SQL code on the `IGNORE_SPACE' setting,
use these guidelines:

   * Avoid creating UDFs or stored functions that have the same name as
     a built-in function.

   * Avoid using function names in non-expression context. For example,
     these statements use `count' (one of the affected function names
     affected by `IGNORE_SPACE'), so they fail with or without
     whitespace following the name if `IGNORE_SPACE' is enabled:

          CREATE TABLE count(i INT);
          CREATE TABLE count (i INT);

     If you must use a function name in non-expression context, write
     it as a quoted identifier:

          CREATE TABLE `count`(i INT);
          CREATE TABLE `count` (i INT);

The number of function names affected by `IGNORE_SPACE' was reduced
significantly in MySQL 5.1.13, from about 200 to about 30. As of MySQL
5.1.13, only the following functions are still affected by the
`IGNORE_SPACE' setting.

`ADDDATE'          `BIT_AND'          `BIT_OR'           `BIT_XOR'
`CAST'             `COUNT'            `CURDATE'          `CURTIME'
`DATE_ADD'         `DATE_SUB'         `EXTRACT'          `GROUP_CONCAT'
`MAX'              `MID'              `MIN'              `NOW'
`POSITION'         `SESSION_USER'     `STD'              `STDDEV'
`STDDEV_POP'       `STDDEV_SAMP'      `SUBDATE'          `SUBSTR'
`SUBSTRING'        `SUM'              `SYSDATE'          `SYSTEM_USER'
`TRIM'             `VARIANCE'         `VAR_POP'          `VAR_SAMP'

For earlier versions of MySQL, check the contents of the
`sql_functions[]' array in the `sql/lex.h' source file to see which
functions are affected by `IGNORE_SPACE'.

*Incompatibility warning*: The change in MySQL 5.1.13 that reduces the
number of function names affected by `IGNORE_SPACE' improves the
consistency of parser operation. However, it also introduces the
possibility of incompatibility for old SQL code that relies on the
following conditions:

   * `IGNORE_SPACE' is disabled.

   * The presence or absence of whitespace following a function name is
     used to distinguish between a built-in function and stored
     function that have the same name, such as `PI()' versus `PI ()'.

For functions that are no longer affected by `IGNORE_SPACE' as of MySQL
5.1.13, that strategy no longer works. Either of the following
approaches can be used if you have code that is subject to the
preceding incompatibility:

   * If a stored function has a name that conflicts with a built-in
     function, refer to the stored function with a schema name
     qualifier, regardless of whether whitespace is present. For
     example, write `SCHEMA_NAME.PI()' or `SCHEMA_NAME.PI ()'.

   * Alternatively, rename the stored function to use a non-conflicting
     name and change invocations of the function to use the new name.

*Function Name Resolution*

The following rules describe how the server resolves references to
function names for function creation and invocation:

   * Built-in functions and user-defined functions

     An error occurs if you try to create a UDF with the same name as a
     built-in function.

   * Built-in functions and stored functions

     It is possible to create a stored function with the same name as a
     built-in function, but to invoke the stored function it is
     necessary to qualify it with a schema name.  For example, if you
     create a stored function named `PI' in the `test' schema, you
     invoke it as `test.PI()' because the server resolves `PI()' as a
     reference to the built-in function. The server creates a warning
     if the stored function name collides with a built-in function
     name. The warning can be displayed with *Note `SHOW WARNINGS':
     show-warnings.

   * User-defined functions and stored functions

     User-defined functions and stored functions share the same
     namespace, so you cannot create a UDF and a stored function with
     the same name.

The preceding function name resolution rules have implications for
upgrading to versions of MySQL that implement new built-in functions:

   * If you have already created a user-defined function with a given
     name and upgrade MySQL to a version that implements a new built-in
     function with the same name, the UDF becomes inaccessible. To
     correct this, use *Note `DROP FUNCTION': drop-function. to drop
     the UDF, and then use *Note `CREATE FUNCTION': create-function. to
     re-create the UDF with a different non-conflicting name.

   * If a new version of MySQL implements a built-in function with the
     same name as an existing stored function, you have two choices:
     Rename the stored function to use a non-conflicting name, or
     change calls to the function so that they use a schema qualifier
     (that is, use `SCHEMA_NAME.FUNC_NAME()' syntax).


File: manual.info,  Node: reserved-words,  Next: user-variables,  Prev: identifiers,  Up: language-structure

8.3 Reserved Words
==================

Certain words such as *Note `SELECT': select, *Note `DELETE': delete, or
*Note `BIGINT': numeric-types. are reserved and require special
treatment for use as identifiers such as table and column names. This
may also be true for the names of built-in functions.

Reserved words are permitted as identifiers if you quote them as
described in *Note identifiers:::

     mysql> CREATE TABLE interval (begin INT, end INT);
     ERROR 1064 (42000): You have an error in your SQL syntax ...
     near 'interval (begin INT, end INT)'

     mysql> CREATE TABLE `interval` (begin INT, end INT);
     Query OK, 0 rows affected (0.01 sec)

Exception: A word that follows a period in a qualified name must be an
identifier, so it need not be quoted even if it is reserved:

     mysql> CREATE TABLE mydb.interval (begin INT, end INT);
     Query OK, 0 rows affected (0.01 sec)

Names of built-in functions are permitted as identifiers but may
require care to be used as such. For example, `COUNT' is acceptable as
a column name. However, by default, no whitespace is allowed in
function invocations between the function name and the following ``(''
character. This requirement enables the parser to distinguish whether
the name is used in a function call or in non-function context. For
further detail on recognition of function names, see *Note
function-resolution::.

The words in the following table are explicitly reserved in MySQL 6.0.
In addition, `_FILENAME' is reserved. At some point, you might upgrade
to a higher version, so it is a good idea to have a look at future
reserved words, too.  You can find these in the manuals that cover
higher versions of MySQL. Most of the words in the table are forbidden
by standard SQL as column or table names (for example, `GROUP'). A few
are reserved because MySQL needs them and uses a `yacc' parser. A
reserved word can be used as an identifier if you quote it.

For a more detailed list of reserved words, including differences
between versions, see Reserved Words in MySQL 6.0
(http://dev.mysql.com/doc/mysqld-version-reference/en/mysqld-version-reference-reservedwords-6-0.html).

`ACCESSIBLE'             `ADD'                    `ALL'
`ALTER'                  `ANALYZE'                `AND'
`AS'                     `ASC'                    `ASENSITIVE'
`BEFORE'                 `BETWEEN'                `BIGINT'
`BINARY'                 `BLOB'                   `BOTH'
`BY'                     `CALL'                   `CASCADE'
`CASE'                   `CHANGE'                 `CHAR'
`CHARACTER'              `CHECK'                  `COLLATE'
`COLUMN'                 `CONDITION'              `CONSTRAINT'
`CONTINUE'               `CONVERT'                `CREATE'
`CROSS'                  `CURRENT_DATE'           `CURRENT_TIME'
`CURRENT_TIMESTAMP'      `CURRENT_USER'           `CURSOR'
`DATABASE'               `DATABASES'              `DAY_HOUR'
`DAY_MICROSECOND'        `DAY_MINUTE'             `DAY_SECOND'
`DEC'                    `DECIMAL'                `DECLARE'
`DEFAULT'                `DELAYED'                `DELETE'
`DESC'                   `DESCRIBE'               `DETERMINISTIC'
`DISTINCT'               `DISTINCTROW'            `DIV'
`DOUBLE'                 `DROP'                   `DUAL'
`EACH'                   `ELSE'                   `ELSEIF'
`ENCLOSED'               `ESCAPED'                `EXISTS'
`EXIT'                   `EXPLAIN'                `FALSE'
`FETCH'                  `FLOAT'                  `FLOAT4'
`FLOAT8'                 `FOR'                    `FORCE'
`FOREIGN'                `FROM'                   `FULLTEXT'
`GRANT'                  `GROUP'                  `HAVING'
`HIGH_PRIORITY'          `HOUR_MICROSECOND'       `HOUR_MINUTE'
`HOUR_SECOND'            `IF'                     `IGNORE'
`IGNORE_SERVER_IDS'      `IN'                     `INDEX'
`INFILE'                 `INNER'                  `INOUT'
`INSENSITIVE'            `INSERT'                 `INT'
`INT1'                   `INT2'                   `INT3'
`INT4'                   `INT8'                   `INTEGER'
`INTERVAL'               `INTO'                   `IS'
`ITERATE'                `JOIN'                   `KEY'
`KEYS'                   `KILL'                   `LEADING'
`LEAVE'                  `LEFT'                   `LIKE'
`LIMIT'                  `LINEAR'                 `LINES'
`LOAD'                   `LOCALTIME'              `LOCALTIMESTAMP'
`LOCK'                   `LONG'                   `LONGBLOB'
`LONGTEXT'               `LOOP'                   `LOW_PRIORITY'
`MASTER_HEARTBEAT_PERIOD'`MASTER_SSL_VERIFY_SERVER_CERT'`MATCH'
`MEDIUMBLOB'             `MEDIUMINT'              `MEDIUMTEXT'
`MIDDLEINT'              `MINUTE_MICROSECOND'     `MINUTE_SECOND'
`MOD'                    `MODIFIES'               `NATURAL'
`NOT'                    `NO_WRITE_TO_BINLOG'     `NULL'
`NUMERIC'                `ON'                     `OPTIMIZE'
`OPTION'                 `OPTIONALLY'             `OR'
`ORDER'                  `OUT'                    `OUTER'
`OUTFILE'                `OVERWRITE'              `PRECISION'
`PRIMARY'                `PROCEDURE'              `PURGE'
`RANGE'                  `READ'                   `READS'
`READ_WRITE'             `REAL'                   `REFERENCES'
`REGEXP'                 `RELEASE'                `RENAME'
`REPEAT'                 `REPLACE'                `REQUIRE'
`RESTRICT'               `RETURN'                 `REVOKE'
`RIGHT'                  `RLIKE'                  `SCHEMA'
`SCHEMAS'                `SECOND_MICROSECOND'     `SELECT'
`SENSITIVE'              `SEPARATOR'              `SET'
`SHOW'                   `SMALLINT'               `SPATIAL'
`SPECIFIC'               `SQL'                    `SQLEXCEPTION'
`SQLSTATE'               `SQLWARNING'             `SQL_BIG_RESULT'
`SQL_CALC_FOUND_ROWS'    `SQL_SMALL_RESULT'       `SSL'
`STARTING'               `STRAIGHT_JOIN'          `TABLE'
`TERMINATED'             `THEN'                   `TINYBLOB'
`TINYINT'                `TINYTEXT'               `TO'
`TRAILING'               `TRIGGER'                `TRUE'
`UNDO'                   `UNION'                  `UNIQUE'
`UNLOCK'                 `UNSIGNED'               `UPDATE'
`USAGE'                  `USE'                    `USING'
`UTC_DATE'               `UTC_TIME'               `UTC_TIMESTAMP'
`VALUES'                 `VARBINARY'              `VARCHAR'
`VARCHARACTER'           `VARYING'                `WHEN'
`WHERE'                  `WHILE'                  `WITH'
`WRITE'                  `XOR'                    `YEAR_MONTH'
`ZEROFILL'                                        

The following are new reserved words in MySQL 6.0:

`IGNORE_SERVER_IDS'      `MASTER_HEARTBEAT_PERIOD'`OVERWRITE'

MySQL allows some keywords to be used as unquoted identifiers because
many people previously used them. Examples are those in the following
list:

   * `ACTION'

   * *Note `BIT': numeric-types.

   * *Note `DATE': datetime.

   * *Note `ENUM': enum.

   * `NO'

   * *Note `TEXT': blob.

   * *Note `TIME': time.

   * *Note `TIMESTAMP': datetime.


File: manual.info,  Node: user-variables,  Next: comments,  Prev: reserved-words,  Up: language-structure

8.4 User-Defined Variables
==========================

You can store a value in a user-defined variable and then refer to it
later. This enables you to pass values from one statement to another.
_User-defined variables are connection-specific_. That is, a user
variable defined by one client cannot be seen or used by other clients.
All variables for a given client connection are automatically freed
when that client exits.

User variables are written as `@VAR_NAME', where the variable name
VAR_NAME may consist of alphanumeric characters from the current
character set, ``.'', ``_'', and ``$''. The default character set is
`latin1' (cp1252 West European). This may be changed with the
`--character-set-server' option to *Note `mysqld': mysqld. See *Note
charset-configuration::. A user variable name can contain other
characters if you quote it as a string or identifier (for example,
`@'my-var'', `@"my-var"', or `@`my-var`').

User variable names not case sensitive in MySQL 5.0 and up.

One way to set a user-defined variable is by issuing a *Note `SET':
set-option.  statement:

     SET @VAR_NAME = EXPR [, @VAR_NAME = EXPR] ...

For *Note `SET': set-option, either `=' or `:=' can be used as the
assignment operator.

You can also assign a value to a user variable in statements other than
*Note `SET': set-option. In this case, the assignment operator must be
`:=' and not `=' because `=' is treated as a comparison operator in
non-*Note `SET': set-option.  statements:

     mysql> SET @t1=0, @t2=0, @t3=0;
     mysql> SELECT @t1:=(@t2:=1)+@t3:=4,@t1,@t2,@t3;
     +----------------------+------+------+------+
     | @t1:=(@t2:=1)+@t3:=4 | @t1  | @t2  | @t3  |
     +----------------------+------+------+------+
     |                    5 |    5 |    1 |    4 |
     +----------------------+------+------+------+

User variables can be assigned a value from a limited set of data
types: integer, decimal, floating-point, binary or non-binary string,
or `NULL' value. Assignment of decimal and real values does not
preserve the precision or scale of the value. A value of a type other
than one of the allowable types is converted to an allowable type. For
example, a value having a temporal or spatial data type is converted to
a binary string.

If a user variable is assigned a non-binary (character) string value,
it has the same character set and collation as the string.  The
coercibility of user variables is implicit. (This is the same
coercibility as for table column values.)

Bit values assigned to user variables are treated as binary strings. To
assign a bit value as a number to a user variable, use `CAST()' or `+0':

     mysql> SET @v1 = b'1000001';
     mysql> SET @v2 = CAST(b'1000001' AS UNSIGNED), @v3 = b'1000001'+0;
     mysql> SELECT @v1, @v2, @v3;
     +------+------+------+
     | @v1  | @v2  | @v3  |
     +------+------+------+
     | A    |   65 |   65 |
     +------+------+------+

If the value of a user variable is selected in a result set, it is
returned to the client as a string.

User variables may be used in contexts where expressions are allowed.
This does not currently include contexts that explicitly require a
literal value, such as in the `LIMIT' clause of a *Note `SELECT':
select. statement, or the `IGNORE N LINES' clause of a *Note `LOAD
DATA': load-data. statement.

If you refer to a variable that has not been initialized, it has a
value of `NULL' and a type of string.

*Note*:

In a *Note `SELECT': select. statement, each expression is evaluated
only when sent to the client. This means that in a `HAVING', `GROUP
BY', or `ORDER BY' clause, you cannot refer to an expression that
involves variables that are set in the *Note `SELECT': select. list.
For example, the following statement does _not_ work as expected:

     mysql> SELECT (@aa:=id) AS a, (@aa+3) AS b FROM TBL_NAME HAVING b=5;

The reference to `b' in the `HAVING' clause refers to an alias for an
expression in the *Note `SELECT': select. list that uses `@aa'. This
does not work as expected: `@aa' contains the value of `id' from the
previous selected row, not from the current row.

The order of evaluation for user variables is undefined and may change
based on the elements contained within a given query. In `SELECT @a, @a
:= @a+1 ...', you might think that MySQL will evaluate `@a' first and
then do an assignment second, but changing the query (for example, by
adding a `GROUP BY', `HAVING', or `ORDER BY' clause) may change the
order of evaluation.

The general rule is never to assign a value to a user variable in one
part of a statement _and_ use the same variable in some other part of
the same statement. You might get the results you expect, but this is
not guaranteed.

Another issue with setting a variable and using it in the same
statement is that the default result type of a variable is based on the
type of the variable at the start of the statement. The following
example illustrates this:

     mysql> SET @a='test';
     mysql> SELECT @a,(@a:=20) FROM TBL_NAME;

For this *Note `SELECT': select. statement, MySQL reports to the client
that column one is a string and converts all accesses of `@a' to
strings, even though @a is set to a number for the second row. After the
*Note `SELECT': select. statement executes, `@a' is regarded as a
number for the next statement.

To avoid problems with this behavior, either do not set and use the
same variable within a single statement, or else set the variable to
`0', `0.0', or `''' to define its type before you use it.

User variables are intended to provide data values. They cannot be used
directly in an SQL statement as an identifier or as part of an
identifier, such as in contexts where a table or database name is
expected, or as a reserved word such as *Note `SELECT': select. This is
true even if the variable is quoted, as shown in the following example:

     mysql> SELECT c1 FROM t;
     +----+
     | c1 |
     +----+
     |  0 |
     +----+
     |  1 |
     +----+
     2 rows in set (0.00 sec)

     mysql> SET @col = "c1";
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @col FROM t;
     +------+
     | @col |
     +------+
     | c1   |
     +------+
     1 row in set (0.00 sec)

     mysql> SELECT `@col` FROM t;
     `ERROR 1054 (42S22): Unknown column '@col' in 'field list''

     mysql> SET @col = "`c1`";
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @col FROM t;
     +------+
     | @col |
     +------+
     | `c1` |
     +------+
     1 row in set (0.00 sec)

An exception to this principle that user variables cannot be used to
provide identifiers is that if you are constructing a string for use as
a prepared statement to be executed later. In this case, user variables
can be used to provide any part of the statement. The following example
illustrates how this can be done:

     mysql> SET @c = "c1";
     Query OK, 0 rows affected (0.00 sec)

     mysql> SET @s = CONCAT("SELECT ", @c, " FROM t");
     Query OK, 0 rows affected (0.00 sec)

     mysql> PREPARE stmt FROM @s;
     Query OK, 0 rows affected (0.04 sec)
     Statement prepared

     mysql> EXECUTE stmt;
     +----+
     | c1 |
     +----+
     |  0 |
     +----+
     |  1 |
     +----+
     2 rows in set (0.00 sec)

     mysql> DEALLOCATE PREPARE stmt;
     Query OK, 0 rows affected (0.00 sec)

See *Note sql-syntax-prepared-statements::, for more information.

A similar technique can be used in application programs to construct
SQL statements using program variables, as shown here using PHP 5:

     <?php
       $mysqli = new mysqli("localhost", "user", "pass", "test");

       if( mysqli_connect_errno() )
         die("Connection failed: %s\n", mysqli_connect_error());

       $col = "c1";

       $query = "SELECT $col FROM t";

       $result = $mysqli->query($query);

       while($row = $result->fetch_assoc())
       {
         echo "<p>" . $row["$col"] . "</p>\n";
       }

       $result->close();

       $mysqli->close();
     ?>

Assembling an SQL statement in this fashion is sometimes known as
`Dynamic SQL'.


File: manual.info,  Node: comments,  Prev: user-variables,  Up: language-structure

8.5 Comment Syntax
==================

MySQL Server supports three comment styles:

   * From a ``#'' character to the end of the line.

   * From a ``-- '' sequence to the end of the line. In MySQL, the ``--
     '' (double-dash) comment style requires the second dash to be
     followed by at least one whitespace or control character (such as
     a space, tab, newline, and so on). This syntax differs slightly
     from standard SQL comment syntax, as discussed in *Note
     ansi-diff-comments::.

   * From a `/*' sequence to the following `*/' sequence, as in the C
     programming language. This syntax allows a comment to extend over
     multiple lines because the beginning and closing sequences need
     not be on the same line.

The following example demonstrates all three comment styles:

     mysql> SELECT 1+1;     # This comment continues to the end of line
     mysql> SELECT 1+1;     -- This comment continues to the end of line
     mysql> SELECT 1 /* this is an in-line comment */ + 1;
     mysql> SELECT 1+
     /*
     this is a
     multiple-line comment
     */
     1;

Nested comments are not supported.

MySQL Server supports some variants of C-style comments. These enable
you to write code that includes MySQL extensions, but is still
portable, by using comments of the following form:

     /*! MYSQL-SPECIFIC CODE */

In this case, MySQL Server parses and executes the code within the
comment as it would any other SQL statement, but other SQL servers will
ignore the extensions. For example, MySQL Server recognizes the
`STRAIGHT_JOIN' keyword in the following statement, but other servers
will not:

     SELECT /*! STRAIGHT_JOIN */ col1 FROM table1,table2 WHERE ...

If you add a version number after the ``!'' character, the syntax within
the comment is executed only if the MySQL version is greater than or
equal to the specified version number. The `TEMPORARY' keyword in the
following comment is executed only by servers from MySQL 3.23.02 or
higher:

     CREATE /*!32302 TEMPORARY */ TABLE t (a INT);

The comment syntax just described applies to how the *Note `mysqld':
mysqld. server parses SQL statements. The *Note `mysql': mysql. client
program also performs some parsing of statements before sending them to
the server. (It does this to determine statement boundaries within a
multiple-statement input line.)

The use of short-form *Note `mysql': mysql. commands such as `\C'
within multi-line `/* ...  */' comments is not supported.


File: manual.info,  Node: internationalization-localization,  Next: data-types,  Prev: language-structure,  Up: Top

9 Internationalization and Localization
***************************************

* Menu:

* charset::                      Character Set Support
* charset-configuration::        The Character Set Used for Data and Sorting
* error-message-language::       Setting the Error Message Language
* adding-character-set::         Adding a New Character Set
* adding-collation::             How to Add a New Collation to a Character Set
* problems-with-character-sets::  Problems With Character Sets
* time-zone-support::            MySQL Server Time Zone Support
* locale-support::               MySQL Server Locale Support

This chapter covers issues of internationalization (MySQL's
capabilities for adapting to local use) and localization (selecting
particular local conventions):

   * MySQL support for character sets in SQL statements.

   * How to configure the server to support different character sets.

   * Selecting the language for error messages.

   * How to set the server's time zone and enable per-connection time
     zone support.

   * Selecting the locale for day and month names.


File: manual.info,  Node: charset,  Next: charset-configuration,  Prev: internationalization-localization,  Up: internationalization-localization

9.1 Character Set Support
=========================

* Menu:

* charset-general::              Character Sets and Collations in General
* charset-mysql::                Character Sets and Collations in MySQL
* charset-syntax::               Specifying Character Sets and Collations
* charset-connection::           Connection Character Sets and Collations
* charset-applications::         Configuring the Character Set and Collation for Applications
* charset-collations::           Collation Issues
* charset-repertoire::           String Repertoire
* charset-operations::           Operations Affected by Character Set Support
* charset-unicode::              Unicode Support
* charset-unicode-upgrading::    Upgrading from Previous to Current Unicode Support
* charset-metadata::             UTF-8 for Metadata
* charset-conversion::           Column Character Set Conversion
* charset-charsets::             Character Sets and Collations That MySQL Supports

MySQL includes character set support that enables you to store data
using a variety of character sets and perform comparisons according to
a variety of collations. You can specify character sets at the server,
database, table, and column level. MySQL supports the use of character
sets for the `MyISAM', `MEMORY', and `InnoDB' storage engines.

This chapter discusses the following topics:

   * What are character sets and collations?

   * The multiple-level default system for character set assignment

   * Syntax for specifying character sets and collations

   * Affected functions and operations

   * Unicode support

   * The character sets and collations that are available, with notes

Character set issues affect not only data storage, but also
communication between client programs and the MySQL server. If you want
the client program to communicate with the server using a character set
different from the default, you'll need to indicate which one. For
example, to use the `utf8' Unicode character set, issue this statement
after connecting to the server:

     SET NAMES 'utf8';

For more information about configuring character sets for application
use and character set-related issues in client/server communication,
see *Note charset-applications::, and *Note charset-connection::.


File: manual.info,  Node: charset-general,  Next: charset-mysql,  Prev: charset,  Up: charset

9.1.1 Character Sets and Collations in General
----------------------------------------------

A _character set_ is a set of symbols and encodings. A _collation_ is a
set of rules for comparing characters in a character set. Let's make the
distinction clear with an example of an imaginary character set.

Suppose that we have an alphabet with four letters: ``A'', ``B'', ``a'',
``b''. We give each letter a number: ``A'' = 0, ``B'' = 1, ``a'' = 2,
``b'' = 3. The letter ``A'' is a symbol, the number 0 is the *encoding*
for ``A'', and the combination of all four letters and their encodings
is a *character set*.

Suppose that we want to compare two string values, ``A'' and ``B''. The
simplest way to do this is to look at the encodings: 0 for ``A'' and 1
for ``B''. Because 0 is less than 1, we say ``A'' is less than ``B''.
What we've just done is apply a collation to our character set. The
collation is a set of rules (only one rule in this case): `compare the
encodings.' We call this simplest of all possible collations a _binary_
collation.

But what if we want to say that the lowercase and uppercase letters are
equivalent? Then we would have at least two rules: (1) treat the
lowercase letters ``a'' and ``b'' as equivalent to ``A'' and ``B''; (2)
then compare the encodings. We call this a _case-insensitive_
collation. It is a little more complex than a binary collation.

In real life, most character sets have many characters: not just ``A''
and ``B'' but whole alphabets, sometimes multiple alphabets or eastern
writing systems with thousands of characters, along with many special
symbols and punctuation marks. Also in real life, most collations have
many rules, not just for whether to distinguish lettercase, but also
for whether to distinguish accents (an `accent' is a mark attached to a
character as in German ``O"''), and for multiple-character mappings
(such as the rule that ``O"'' = ``OE'' in one of the two German
collations).

MySQL can do these things for you:

   * Store strings using a variety of character sets

   * Compare strings using a variety of collations

   * Mix strings with different character sets or collations in the
     same server, the same database, or even the same table

   * Allow specification of character set and collation at any level

In these respects, MySQL is far ahead of most other database management
systems. However, to use these features effectively, you need to know
what character sets and collations are available, how to change the
defaults, and how they affect the behavior of string operators and
functions.


File: manual.info,  Node: charset-mysql,  Next: charset-syntax,  Prev: charset-general,  Up: charset

9.1.2 Character Sets and Collations in MySQL
--------------------------------------------

The MySQL server can support multiple character sets. To list the
available character sets, use the *Note `SHOW CHARACTER SET':
show-character-set. statement. A partial listing follows.  For more
complete information, see *Note charset-charsets::.

     mysql> SHOW CHARACTER SET;
     +----------+-----------------------------+---------------------+--------+
     | Charset  | Description                 | Default collation   | Maxlen |
     +----------+-----------------------------+---------------------+--------+
     | big5     | Big5 Traditional Chinese    | big5_chinese_ci     |      2 |
     | dec8     | DEC West European           | dec8_swedish_ci     |      1 |
     | cp850    | DOS West European           | cp850_general_ci    |      1 |
     | hp8      | HP West European            | hp8_english_ci      |      1 |
     | koi8r    | KOI8-R Relcom Russian       | koi8r_general_ci    |      1 |
     | latin1   | cp1252 West European        | latin1_swedish_ci   |      1 |
     | latin2   | ISO 8859-2 Central European | latin2_general_ci   |      1 |
     | swe7     | 7bit Swedish                | swe7_swedish_ci     |      1 |
     | ascii    | US ASCII                    | ascii_general_ci    |      1 |
     | ujis     | EUC-JP Japanese             | ujis_japanese_ci    |      3 |
     | sjis     | Shift-JIS Japanese          | sjis_japanese_ci    |      2 |
     | hebrew   | ISO 8859-8 Hebrew           | hebrew_general_ci   |      1 |
     | tis620   | TIS620 Thai                 | tis620_thai_ci      |      1 |
     | euckr    | EUC-KR Korean               | euckr_korean_ci     |      2 |
     | koi8u    | KOI8-U Ukrainian            | koi8u_general_ci    |      1 |
     | gb2312   | GB2312 Simplified Chinese   | gb2312_chinese_ci   |      2 |
     | greek    | ISO 8859-7 Greek            | greek_general_ci    |      1 |
     | cp1250   | Windows Central European    | cp1250_general_ci   |      1 |
     | gbk      | GBK Simplified Chinese      | gbk_chinese_ci      |      2 |
     | latin5   | ISO 8859-9 Turkish          | latin5_turkish_ci   |      1 |
     ...

Any given character set always has at least one collation. It may have
several collations. To list the collations for a character set, use the
*Note `SHOW COLLATION': show-collation. statement. For example, to see
the collations for the `latin1' (cp1252 West European) character set,
use this statement to find those collation names that begin with
`latin1':

     mysql> SHOW COLLATION LIKE 'latin1%';
     +---------------------+---------+----+---------+----------+---------+
     | Collation           | Charset | Id | Default | Compiled | Sortlen |
     +---------------------+---------+----+---------+----------+---------+
     | latin1_german1_ci   | latin1  |  5 |         |          |       0 |
     | latin1_swedish_ci   | latin1  |  8 | Yes     | Yes      |       1 |
     | latin1_danish_ci    | latin1  | 15 |         |          |       0 |
     | latin1_german2_ci   | latin1  | 31 |         | Yes      |       2 |
     | latin1_bin          | latin1  | 47 |         | Yes      |       1 |
     | latin1_general_ci   | latin1  | 48 |         |          |       0 |
     | latin1_general_cs   | latin1  | 49 |         |          |       0 |
     | latin1_spanish_ci   | latin1  | 94 |         |          |       0 |
     +---------------------+---------+----+---------+----------+---------+

The `latin1' collations have the following meanings.

*Collation*                   *Meaning*
`latin1_german1_ci'           German DIN-1
`latin1_swedish_ci'           Swedish/Finnish
`latin1_danish_ci'            Danish/Norwegian
`latin1_german2_ci'           German DIN-2
`latin1_bin'                  Binary according to `latin1' encoding
`latin1_general_ci'           Multilingual (Western European)
`latin1_general_cs'           Multilingual (ISO Western European), case
                              sensitive
`latin1_spanish_ci'           Modern Spanish

Collations have these general characteristics:

   * Two different character sets cannot have the same collation.

   * Each character set has one collation that is the _default
     collation_. For example, the default collation for `latin1' is
     `latin1_swedish_ci'. The output for *Note `SHOW CHARACTER SET':
     show-character-set. indicates which collation is the default for
     each displayed character set.

   * There is a convention for collation names: They start with the
     name of the character set with which they are associated, they
     usually include a language name, and they end with `_ci' (case
     insensitive), `_cs' (case sensitive), or `_bin' (binary).

In cases where a character set has multiple collations, it might not be
clear which collation is most suitable for a given application. To
avoid choosing the wrong collation, it can be helpful to perform some
comparisons with representative data values to make sure that a given
collation sorts values the way you expect.

Collation-Charts.Org (http://www.collation-charts.org/) is a useful
site for information that shows how one collation compares to another.


File: manual.info,  Node: charset-syntax,  Next: charset-connection,  Prev: charset-mysql,  Up: charset

9.1.3 Specifying Character Sets and Collations
----------------------------------------------

* Menu:

* charset-server::               Server Character Set and Collation
* charset-database::             Database Character Set and Collation
* charset-table::                Table Character Set and Collation
* charset-column::               Column Character Set and Collation
* charset-literal::              Character String Literal Character Set and Collation
* charset-national::             National Character Set
* charset-examples::             Examples of Character Set and Collation Assignment
* charset-compatibility::        Compatibility with Other DBMSs

There are default settings for character sets and collations at four
levels: server, database, table, and column. The description in the
following sections may appear complex, but it has been found in
practice that multiple-level defaulting leads to natural and obvious
results.

`CHARACTER SET' is used in clauses that specify a character set.
`CHARSET' may be used as a synonym for `CHARACTER SET'.

Character set issues affect not only data storage, but also
communication between client programs and the MySQL server. If you want
the client program to communicate with the server using a character set
different from the default, you'll need to indicate which one. For
example, to use the `utf8' Unicode character set, issue this statement
after connecting to the server:

     SET NAMES 'utf8';

For more information about character set-related issues in
client/server communication, see *Note charset-connection::.


File: manual.info,  Node: charset-server,  Next: charset-database,  Prev: charset-syntax,  Up: charset-syntax

9.1.3.1 Server Character Set and Collation
..........................................

MySQL Server has a server character set and a server collation. These
can be set at server startup on the command line or in an option file
and changed at runtime.

Initially, the server character set and collation depend on the options
that you use when you start *Note `mysqld': mysqld. You can use
`--character-set-server' for the character set. Along with it, you can
add `--collation-server' for the collation. If you don't specify a
character set, that is the same as saying
`--character-set-server=latin1'.  If you specify only a character set
(for example, `latin1') but not a collation, that is the same as saying
`--character-set-server=latin1' `--collation-server=latin1_swedish_ci'
because `latin1_swedish_ci' is the default collation for `latin1'.
Therefore, the following three commands all have the same effect:

     shell> mysqld
     shell> mysqld --character-set-server=latin1
     shell> mysqld --character-set-server=latin1 \
                --collation-server=latin1_swedish_ci

One way to change the settings is by recompiling. If you want to change
the default server character set and collation when building from
sources, use: `--with-charset' and `--with-collation' as arguments for
`configure'. For example:

     shell> ./configure --with-charset=latin1

Or:

     shell> ./configure --with-charset=latin1 \
                --with-collation=latin1_german1_ci

Both *Note `mysqld': mysqld. and `configure' verify that the character
set/collation combination is valid. If not, each program displays an
error message and terminates.

The server character set and collation are used as default values if
the database character set and collation are not specified in *Note
`CREATE DATABASE': create-database.  statements. They have no other
purpose.

The current server character set and collation can be determined from
the values of the `character_set_server' and `collation_server' system
variables. These variables can be changed at runtime.


File: manual.info,  Node: charset-database,  Next: charset-table,  Prev: charset-server,  Up: charset-syntax

9.1.3.2 Database Character Set and Collation
............................................

Every database has a database character set and a database collation.
The *Note `CREATE DATABASE': create-database.  and *Note `ALTER
DATABASE': alter-database. statements have optional clauses for
specifying the database character set and collation:

     CREATE DATABASE DB_NAME
         [[DEFAULT] CHARACTER SET CHARSET_NAME]
         [[DEFAULT] COLLATE COLLATION_NAME]

     ALTER DATABASE DB_NAME
         [[DEFAULT] CHARACTER SET CHARSET_NAME]
         [[DEFAULT] COLLATE COLLATION_NAME]

The keyword `SCHEMA' can be used instead of `DATABASE'.

All database options are stored in a text file named `db.opt' that can
be found in the database directory.

The `CHARACTER SET' and `COLLATE' clauses make it possible to create
databases with different character sets and collations on the same
MySQL server.

Example:

     CREATE DATABASE DB_NAME CHARACTER SET latin1 COLLATE latin1_swedish_ci;

MySQL chooses the database character set and database collation in the
following manner:

   * If both `CHARACTER SET X' and `COLLATE Y' are specified, character
     set X and collation Y are used.

   * If `CHARACTER SET X' is specified without `COLLATE', character set
     X and its default collation are used. To see the default collation
     for each character set, use the *Note `SHOW COLLATION':
     show-collation.  statement.

   * If `COLLATE Y' is specified without `CHARACTER SET', the character
     set associated with Y and collation Y are used.

   * Otherwise, the server character set and server collation are used.

The database character set and collation are used as default values for
table definitions if the table character set and collation are not
specified in *Note `CREATE TABLE': create-table. statements. The
database character set also is used by *Note `LOAD DATA INFILE':
load-data. The character set and collation have no other purposes.

The character set and collation for the default database can be
determined from the values of the `character_set_database' and
`collation_database' system variables. The server sets these variables
whenever the default database changes. If there is no default database,
the variables have the same value as the corresponding server-level
system variables, `character_set_server' and `collation_server'.


File: manual.info,  Node: charset-table,  Next: charset-column,  Prev: charset-database,  Up: charset-syntax

9.1.3.3 Table Character Set and Collation
.........................................

Every table has a table character set and a table collation.  The *Note
`CREATE TABLE': create-table. and *Note `ALTER TABLE': alter-table.
statements have optional clauses for specifying the table character set
and collation:

     CREATE TABLE TBL_NAME (COLUMN_LIST)
         [[DEFAULT] CHARACTER SET CHARSET_NAME]
         [COLLATE COLLATION_NAME]]

     ALTER TABLE TBL_NAME
         [[DEFAULT] CHARACTER SET CHARSET_NAME]
         [COLLATE COLLATION_NAME]

Example:

     CREATE TABLE t1 ( ... )
     CHARACTER SET latin1 COLLATE latin1_danish_ci;

MySQL chooses the table character set and collation in the following
manner:

   * If both `CHARACTER SET X' and `COLLATE Y' are specified, character
     set X and collation Y are used.

   * If `CHARACTER SET X' is specified without `COLLATE', character set
     X and its default collation are used. To see the default collation
     for each character set, use the *Note `SHOW COLLATION':
     show-collation.  statement.

   * If `COLLATE Y' is specified without `CHARACTER SET', the character
     set associated with Y and collation Y are used.

   * Otherwise, the database character set and collation are used.

The table character set and collation are used as default values for
column definitions if the column character set and collation are not
specified in individual column definitions.  The table character set
and collation are MySQL extensions; there are no such things in
standard SQL.


File: manual.info,  Node: charset-column,  Next: charset-literal,  Prev: charset-table,  Up: charset-syntax

9.1.3.4 Column Character Set and Collation
..........................................

Every `character' column (that is, a column of type *Note `CHAR': char,
*Note `VARCHAR': char, or *Note `TEXT': blob.) has a column character
set and a column collation. Column definition syntax for *Note `CREATE
TABLE': create-table. and *Note `ALTER TABLE': alter-table. has optional
clauses for specifying the column character set and collation:

     COL_NAME {CHAR | VARCHAR | TEXT} (COL_LENGTH)
         [CHARACTER SET CHARSET_NAME]
         [COLLATE COLLATION_NAME]

These clauses can also be used for *Note `ENUM': enum. and *Note `SET':
set. columns:

     COL_NAME {ENUM | SET} (VAL_LIST)
         [CHARACTER SET CHARSET_NAME]
         [COLLATE COLLATION_NAME]

Examples:

     CREATE TABLE t1
     (
         col1 VARCHAR(5)
           CHARACTER SET latin1
           COLLATE latin1_german1_ci
     );

     ALTER TABLE t1 MODIFY
         col1 VARCHAR(5)
           CHARACTER SET latin1
           COLLATE latin1_swedish_ci;

MySQL chooses the column character set and collation in the following
manner:

   * If both `CHARACTER SET X' and `COLLATE Y' are specified, character
     set X and collation Y are used.

          CREATE TABLE t1
          (
              col1 CHAR(10) CHARACTER SET utf8 COLLATE utf8_unicode_ci
          ) CHARACTER SET latin1 COLLATE latin1_bin;

     The character set and collation are specified for the column, so
     they are used. The column has character set `utf8' and collation
     `utf8_unicode_ci'.

   * If `CHARACTER SET X' is specified without `COLLATE', character set
     X and its default collation are used.

          CREATE TABLE t1
          (
              col1 CHAR(10) CHARACTER SET utf8
          ) CHARACTER SET latin1 COLLATE latin1_bin;

     The character set is specified for the column, but the collation
     is not. The column has character set `utf8' and the default
     collation for `utf8', which is `utf8_general_ci'. To see the
     default collation for each character set, use the *Note `SHOW
     COLLATION': show-collation. statement.

   * If `COLLATE Y' is specified without `CHARACTER SET', the character
     set associated with Y and collation Y are used.

          CREATE TABLE t1
          (
              col1 CHAR(10) COLLATE utf8_polish_ci
          ) CHARACTER SET latin1 COLLATE latin1_bin;

     The collation is specified for the column, but the character set
     is not. The column has collation `utf8_polish_ci' and the
     character set is the one associated with the collation, which is
     `utf8'.

   * Otherwise, the table character set and collation are used.

          CREATE TABLE t1
          (
              col1 CHAR(10)
          ) CHARACTER SET latin1 COLLATE latin1_bin;

     Neither the character set nor collation are specified for the
     column, so the table defaults are used. The column has character
     set `latin1' and collation `latin1_bin'.

The `CHARACTER SET' and `COLLATE' clauses are standard SQL.

If you use *Note `ALTER TABLE': alter-table. to convert a column from
one character set to another, MySQL attempts to map the data values,
but if the character sets are incompatible, there may be data loss.


File: manual.info,  Node: charset-literal,  Next: charset-national,  Prev: charset-column,  Up: charset-syntax

9.1.3.5 Character String Literal Character Set and Collation
............................................................

Every character string literal has a character set and a collation.

A character string literal may have an optional character set
introducer and `COLLATE' clause:

     [_CHARSET_NAME]'STRING' [COLLATE COLLATION_NAME]

Examples:

     SELECT 'STRING';
     SELECT _latin1'STRING';
     SELECT _latin1'STRING' COLLATE latin1_danish_ci;

For the simple statement `SELECT 'STRING'', the string has the
character set and collation defined by the `character_set_connection'
and `collation_connection' system variables.

The `_CHARSET_NAME' expression is formally called an _introducer_. It
tells the parser, `the string that is about to follow uses character set
X.' Because this has confused people in the past, we emphasize that an
introducer does not change the string to the introducer character set
like `CONVERT()' would do. It does not change the string's value,
although padding may occur. The introducer is just a signal. An
introducer is also legal before standard hex literal and numeric hex
literal notation (`x'LITERAL'' and `0xNNNN'), or before bit-field
literal notation (`b'LITERAL'' and `0bNNNN').

Examples:

     SELECT _latin1 x'AABBCC';
     SELECT _latin1 0xAABBCC;
     SELECT _latin1 b'1100011';
     SELECT _latin1 0b1100011;

MySQL determines a literal's character set and collation in the
following manner:

   * If both _X and `COLLATE Y' are specified, character set X and
     collation Y are used.

   * If _X is specified but `COLLATE' is not specified, character set X
     and its default collation are used. To see the default collation
     for each character set, use the *Note `SHOW COLLATION':
     show-collation.  statement.

   * Otherwise, the character set and collation given by the
     `character_set_connection' and `collation_connection' system
     variables are used.

Examples:

   * A string with `latin1' character set and `latin1_german1_ci'
     collation:

          SELECT _latin1'Mu"ller' COLLATE latin1_german1_ci;

   * A string with `latin1' character set and its default collation
     (that is, `latin1_swedish_ci'):

          SELECT _latin1'Mu"ller';

   * A string with the connection default character set and collation:

          SELECT 'Mu"ller';

Character set introducers and the `COLLATE' clause are implemented
according to standard SQL specifications.

An introducer indicates the character set for the following string, but
does not change now how the parser performs escape processing within
the string. Escapes are always interpreted by the parser according to
the character set given by `character_set_connection'.

The following examples show that escape processing occurs using
`character_set_connection' even in the presence of an introducer. The
examples use `SET NAMES' (which changes `character_set_connection', as
discussed in *Note charset-connection::), and display the resulting
strings using the `HEX()' function so that the exact string contents
can be seen.

Example 1:

     mysql> SET NAMES latin1;
     Query OK, 0 rows affected (0.01 sec)

     mysql> SELECT HEX('a`\n'), HEX(_sjis'a`\n');
     +------------+-----------------+
     | HEX('a`\n') | HEX(_sjis'a`\n') |
     +------------+-----------------+
     | E00A       | E00A            |
     +------------+-----------------+
     1 row in set (0.00 sec)

Here, ``a`'' (hex value `E0') is followed by ``\n'', the escape
sequence for newline. The escape sequence is interpreted using the
`character_set_connection' value of `latin1' to produce a literal
newline (hex value `0A'). This happens even for the second string. That
is, the introducer of `_sjis' does not affect the parser's escape
processing.

Example 2:

     mysql> SET NAMES sjis;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT HEX('a`\n'), HEX(_latin1'a`\n');
     +------------+-------------------+
     | HEX('a`\n') | HEX(_latin1'a`\n') |
     +------------+-------------------+
     | E05C6E     | E05C6E            |
     +------------+-------------------+
     1 row in set (0.04 sec)

Here, `character_set_connection' is `sjis', a character set in which
the sequence of ``a`'' followed by ``\'' (hex values `05' and `5C') is
a valid multi-byte character. Hence, the first two bytes of the string
are interpreted as a single `sjis' character, and the ``\'' is not
interpreted as an escape character. The following ``n'' (hex value
`6E') is not interpreted as part of an escape sequence. This is true
even for the second string; the introducer of `_latin1' does not affect
escape processing.


File: manual.info,  Node: charset-national,  Next: charset-examples,  Prev: charset-literal,  Up: charset-syntax

9.1.3.6 National Character Set
..............................

Standard SQL defines *Note `NCHAR': char. or *Note `NATIONAL CHAR':
char. as a way to indicate that a *Note `CHAR': char. column should use
some predefined character set. MySQL 6.0 uses `utf8' as this predefined
character set. For example, these data type declarations are equivalent:

     CHAR(10) CHARACTER SET utf8
     NATIONAL CHARACTER(10)
     NCHAR(10)

As are these:

     VARCHAR(10) CHARACTER SET utf8
     NATIONAL VARCHAR(10)
     NCHAR VARCHAR(10)
     NATIONAL CHARACTER VARYING(10)
     NATIONAL CHAR VARYING(10)

You can use `N'LITERAL'' (or `n'LITERAL'') to create a string in the
national character set. These statements are equivalent:

     SELECT N'some text';
     SELECT n'some text';
     SELECT _utf8'some text';

For information on upgrading character sets to MySQL 6.0 from versions
prior to 4.1, see the `MySQL 3.23, 4.0, 4.1 Reference Manual'.


File: manual.info,  Node: charset-examples,  Next: charset-compatibility,  Prev: charset-national,  Up: charset-syntax

9.1.3.7 Examples of Character Set and Collation Assignment
..........................................................

The following examples show how MySQL determines default character set
and collation values.

*Example 1: Table and Column Definition*

     CREATE TABLE t1
     (
         c1 CHAR(10) CHARACTER SET latin1 COLLATE latin1_german1_ci
     ) DEFAULT CHARACTER SET latin2 COLLATE latin2_bin;

Here we have a column with a `latin1' character set and a
`latin1_german1_ci' collation. The definition is explicit, so that is
straightforward. Notice that there is no problem with storing a
`latin1' column in a `latin2' table.

*Example 2: Table and Column Definition*

     CREATE TABLE t1
     (
         c1 CHAR(10) CHARACTER SET latin1
     ) DEFAULT CHARACTER SET latin1 COLLATE latin1_danish_ci;

This time we have a column with a `latin1' character set and a default
collation. Although it might seem natural, the default collation is not
taken from the table level. Instead, because the default collation for
`latin1' is always `latin1_swedish_ci', column `c1' has a collation of
`latin1_swedish_ci' (not `latin1_danish_ci').

*Example 3: Table and Column Definition*

     CREATE TABLE t1
     (
         c1 CHAR(10)
     ) DEFAULT CHARACTER SET latin1 COLLATE latin1_danish_ci;

We have a column with a default character set and a default collation.
In this circumstance, MySQL checks the table level to determine the
column character set and collation.  Consequently, the character set
for column `c1' is `latin1' and its collation is `latin1_danish_ci'.

*Example 4: Database, Table, and Column Definition*

     CREATE DATABASE d1
         DEFAULT CHARACTER SET latin2 COLLATE latin2_czech_ci;
     USE d1;
     CREATE TABLE t1
     (
         c1 CHAR(10)
     );

We create a column without specifying its character set and collation.
We're also not specifying a character set and a collation at the table
level. In this circumstance, MySQL checks the database level to
determine the table settings, which thereafter become the column
settings.) Consequently, the character set for column `c1' is `latin2'
and its collation is `latin2_czech_ci'.


File: manual.info,  Node: charset-compatibility,  Prev: charset-examples,  Up: charset-syntax

9.1.3.8 Compatibility with Other DBMSs
......................................

For MaxDB compatibility these two statements are the same:

     CREATE TABLE t1 (f1 CHAR(N) UNICODE);
     CREATE TABLE t1 (f1 CHAR(N) CHARACTER SET ucs2);


File: manual.info,  Node: charset-connection,  Next: charset-applications,  Prev: charset-syntax,  Up: charset

9.1.4 Connection Character Sets and Collations
----------------------------------------------

Several character set and collation system variables relate to a
client's interaction with the server. Some of these have been mentioned
in earlier sections:

   * The server character set and collation can be determined from the
     values of the `character_set_server' and `collation_server' system
     variables.

   * The character set and collation of the default database can be
     determined from the values of the `character_set_database' and
     `collation_database' system variables.

Additional character set and collation system variables are involved in
handling traffic for the connection between a client and the server.
Every client has connection-related character set and collation system
variables.

Consider what a `connection' is: It is what you make when you connect
to the server. The client sends SQL statements, such as queries, over
the connection to the server.  The server sends responses, such as
result sets, over the connection back to the client. This leads to
several questions about character set and collation handling for client
connections, each of which can be answered in terms of system variables:

   * What character set is the statement in when it leaves the client?

     The server takes the `character_set_client' system variable to be
     the character set in which statements are sent by the client.

   * What character set should the server translate a statement to
     after receiving it?

     For this, the server uses the `character_set_connection' and
     `collation_connection' system variables. It converts statements
     sent by the client from `character_set_client' to
     `character_set_connection' (except for string literals that have
     an introducer such as `_latin1' or `_utf8').
     `collation_connection' is important for comparisons of literal
     strings. For comparisons of strings with column values,
     `collation_connection' does not matter because columns have their
     own collation, which has a higher collation precedence.

   * What character set should the server translate to before shipping
     result sets or error messages back to the client?

     The `character_set_results' system variable indicates the
     character set in which the server returns query results to the
     client. This includes result data such as column values, and
     result metadata such as column names.

You can fine-tune the settings for these variables, or you can depend
on the defaults (in which case, you can skip the rest of this section).
If you do not use the defaults, you must change the character settings
_for each connection to the server._

There are two statements that affect the connection character sets:

     SET NAMES 'CHARSET_NAME'
     SET CHARACTER SET CHARSET_NAME

`SET NAMES' indicates what character set the client will use to send
SQL statements to the server. Thus, `SET NAMES 'cp1251'' tells the
server `future incoming messages from this client are in character set
`cp1251'.' It also specifies the character set that the server should
use for sending results back to the client. (For example, it indicates
what character set to use for column values if you use a *Note
`SELECT': select. statement.)

A `SET NAMES 'X'' statement is equivalent to these three statements:

     SET character_set_client = X;
     SET character_set_results = X;
     SET character_set_connection = X;

Setting `character_set_connection' to X also sets
`collation_connection' to the default collation for X. It is not
necessary to set that collation explicitly. To specify a particular
collation for the character sets, use the optional `COLLATE' clause:

     SET NAMES 'CHARSET_NAME' COLLATE 'COLLATION_NAME'

`SET CHARACTER SET' is similar to `SET NAMES' but sets
`character_set_connection' and `collation_connection' to
`character_set_database' and `collation_database'. A `SET CHARACTER SET
X' statement is equivalent to these three statements:

     SET character_set_client = X;
     SET character_set_results = X;
     SET collation_connection = @@collation_database;

Setting `collation_connection' also sets `character_set_connection' to
the character set associated with the collation (equivalent to
executing `SET character_set_connection = @@character_set_database').
It is not necessary to set `character_set_connection' explicitly.

When a client connects, it sends to the server the name of the
character set that it wants to use. The server uses the name to set the
`character_set_client', `character_set_results', and
`character_set_connection' system variables. In effect, the server
performs a `SET NAMES' operation using the character set name.

With the *Note `mysql': mysql. client, it is not necessary to execute
`SET NAMES' every time you start up if you want to use a character set
different from the default. You can add the `--default-character-set'
option setting to your *Note `mysql': mysql. statement line, or in your
option file. For example, the following option file setting changes the
three character set variables set to `koi8r' each time you invoke *Note
`mysql': mysql.:

     [mysql]
     default-character-set=koi8r

If you are using the *Note `mysql': mysql. client with auto-reconnect
enabled (which is not recommended), it is preferable to use the
`charset' command rather than `SET NAMES'. For example:

     mysql> charset utf8
     Charset changed

The `charset' command issues a `SET NAMES' statement, and also changes
the default character set that is used if *Note `mysql': mysql.
reconnects after the connection has dropped.

Example: Suppose that `column1' is defined as `CHAR(5) CHARACTER SET
latin2'. If you do not say `SET NAMES' or `SET CHARACTER SET', then for
`SELECT column1 FROM t', the server sends back all the values for
`column1' using the character set that the client specified when it
connected. On the other hand, if you say `SET NAMES 'latin1'' or `SET
CHARACTER SET latin1' before issuing the *Note `SELECT': select.
statement, the server converts the `latin2' values to `latin1' just
before sending results back.  Conversion may be lossy if there are
characters that are not in both character sets.

If you do not want the server to perform any conversion of result sets,
set `character_set_results' to `NULL' or `binary':

     SET character_set_results = NULL;

*Note*:

`ucs2', `utf16', and `utf32' cannot be used as a client character set,
which means that they do not work for `SET NAMES' or `SET CHARACTER
SET'.

To see the values of the character set and collation system variables
that apply to your connection, use these statements:

     SHOW VARIABLES LIKE 'character_set%';
     SHOW VARIABLES LIKE 'collation%';

You must also consider the environment within which your MySQL
applications execute. See *Note charset-applications::.


File: manual.info,  Node: charset-applications,  Next: charset-collations,  Prev: charset-connection,  Up: charset

9.1.5 Configuring the Character Set and Collation for Applications
------------------------------------------------------------------

For applications that store data using the default MySQL character set
and collation (`latin1', `latin1_swedish_ci'), no special configuration
should be needed. If applications require data storage using a
different character set or collation, you can configure character set
information several ways:

   * Specify character settings per database. For example, applications
     that use one database might require `utf8', whereas applications
     that use another database might require `sjis'.

   * Specify character settings at server startup. This causes the
     server to use the given settings for all applications that do not
     make other arrangements.

   * Specify character settings at configuration time, if you build
     MySQL from source. This causes the server to use the given
     settings for all applications, without having to specify them at
     server startup.

When different applications require different character settings, the
per-database technique provides a good deal of flexibility. If most or
all applications use the same character set, specifying character
settings at server startup or configuration time may be most convenient.

For the per-database or server-startup techniques, the settings control
the character set for data storage. Applications must also tell the
server which character set to use for client/server communications, as
described in the following instructions.

The examples shown here assume use of the `utf8' character set and
`utf8_general_ci' collation.

*Specify character settings per database.* To create a database such
that its tables will use a given default character set and collation
for data storage, use a *Note `CREATE DATABASE': create-database.
statement like this:

     CREATE DATABASE mydb
       DEFAULT CHARACTER SET utf8
       DEFAULT COLLATE utf8_general_ci;

Tables created in the database will use `utf8' and `utf8_general_ci' by
default for any character columns.

Applications that use the database should also configure their
connection to the server each time they connect. This can be done by
executing a `SET NAMES 'utf8'' statement after connecting. The
statement can be used regardless of connection method: The *Note
`mysql': mysql. client, PHP scripts, and so forth.

In some cases, it may be possible to configure the connection to use
the desired character set some other way. For example, for connections
made using *Note `mysql': mysql, you can specify the
`--default-character-set=utf8' command-line option to achieve the same
effect as `SET NAMES 'utf8''.

For more information about configuring client connections, see *Note
charset-connection::.

*Specify character settings at server startup.* To select a character
set and collation at server startup, use the `--character-set-server'
and `--collation-server' options. For example, to specify the options
in an option file, include these lines:

     [mysqld]
     character-set-server=utf8
     collation-server=utf8_general_ci

These settings apply server-wide and apply as the defaults for
databases created by any application, and for tables created in those
databases.

It is still necessary for applications to configure their connection
using `SET NAMES' or equivalent after they connect, as described
previously. You might be tempted to start the server with the
`--init_connect="SET NAMES 'utf8'"' option to cause `SET NAMES' to be
executed automatically for each client that connects. However, this will
yield inconsistent results because the `init_connect' value is not
executed for users who have the `SUPER' privilege.

*Specify character settings at MySQL configuration time.* To select a
character set and collation when you configure and build MySQL from
source, use the `--with-charset' and `--with-collation' options:

     shell> ./configure --with-charset=utf8 --with-collation=utf8_general_ci

The resulting server uses `utf8' and `utf8_general_ci' as the default
for databases and tables and for client connections. It is unnecessary
to use `--character-set-server' and `--collation-server' at server
startup. It is also unnecessary for applications to configure their
connection using `SET NAMES' or equivalent after they connect to the
server.

Regardless of how you configure the MySQL character set for application
use, you must also consider the environment within which those
applications execute. If you will send statements using UTF-8 text
taken from a file that you create in an editor, you should edit the
file with the locale of your environment set to UTF-8 so that the
file's encoding is correct and so that the operating system handles it
correctly. If you use the *Note `mysql': mysql. client from within a
terminal window, the window must be configured to use UTF-8 or
characters may not display properly. For a script that executes in a Web
environment, the script must handle character encoding properly for its
interaction with the MySQL server, and it must generate pages that
correctly indicate the encoding so that browsers know how to display
the content of the pages. For example, you can include this `<meta>'
tag within your `<head>' element:

     <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />


File: manual.info,  Node: charset-collations,  Next: charset-repertoire,  Prev: charset-applications,  Up: charset

9.1.6 Collation Issues
----------------------

* Menu:

* charset-collate::              Using `COLLATE' in SQL Statements
* charset-collate-precedence::   `COLLATE' Clause Precedence
* charset-binary-op::            `BINARY' Operator
* charset-binary-collations::    The `_bin' and `binary' Collations
* charset-collate-tricky::       Special Cases Where Collation Determination Is Tricky
* charset-collation-charset::    Collations Must Be for the Right Character Set
* charset-collation-effect::     Examples of the Effect of Collation

The following sections discuss various aspects of character set
collations.


File: manual.info,  Node: charset-collate,  Next: charset-collate-precedence,  Prev: charset-collations,  Up: charset-collations

9.1.6.1 Using `COLLATE' in SQL Statements
.........................................

With the `COLLATE' clause, you can override whatever the default
collation is for a comparison.  `COLLATE' may be used in various parts
of SQL statements. Here are some examples:

   * With `ORDER BY':

          SELECT k
          FROM t1
          ORDER BY k COLLATE latin1_german2_ci;

   * With `AS':

          SELECT k COLLATE latin1_german2_ci AS k1
          FROM t1
          ORDER BY k1;

   * With `GROUP BY':

          SELECT k
          FROM t1
          GROUP BY k COLLATE latin1_german2_ci;

   * With aggregate functions:

          SELECT MAX(k COLLATE latin1_german2_ci)
          FROM t1;

   * With `DISTINCT':

          SELECT DISTINCT k COLLATE latin1_german2_ci
          FROM t1;

   * With `WHERE':

               SELECT *
               FROM t1
               WHERE _latin1 'Mu"ller' COLLATE latin1_german2_ci = k;

               SELECT *
               FROM t1
               WHERE k LIKE _latin1 'Mu"ller' COLLATE latin1_german2_ci;

   * With `HAVING':

          SELECT k
          FROM t1
          GROUP BY k
          HAVING k = _latin1 'Mu"ller' COLLATE latin1_german2_ci;


File: manual.info,  Node: charset-collate-precedence,  Next: charset-binary-op,  Prev: charset-collate,  Up: charset-collations

9.1.6.2 `COLLATE' Clause Precedence
...................................

The `COLLATE' clause has high precedence (higher than `||'), so the
following two expressions are equivalent:

     x || y COLLATE z
     x || (y COLLATE z)


File: manual.info,  Node: charset-binary-op,  Next: charset-binary-collations,  Prev: charset-collate-precedence,  Up: charset-collations

9.1.6.3 `BINARY' Operator
.........................

The `BINARY' operator casts the string following it to a binary string.
This is an easy way to force a comparison to be done byte by byte
rather than character by character. `BINARY' also causes trailing
spaces to be significant.

     mysql> SELECT 'a' = 'A';
             -> 1
     mysql> SELECT BINARY 'a' = 'A';
             -> 0
     mysql> SELECT 'a' = 'a ';
             -> 1
     mysql> SELECT BINARY 'a' = 'a ';
             -> 0

`BINARY STR' is shorthand for `CAST(STR AS BINARY)'.

The `BINARY' attribute in character column definitions has a different
effect. A character column defined with the `BINARY' attribute is
assigned the binary collation of the column's character set. Every
character set has a binary collation. For example, the binary collation
for the `latin1' character set is `latin1_bin', so if the table default
character set is `latin1', these two column definitions are equivalent:

     CHAR(10) BINARY
     CHAR(10) CHARACTER SET latin1 COLLATE latin1_bin

The effect of `BINARY' as a column attribute differs from its effect
prior to MySQL 4.1. Formerly, `BINARY' resulted in a column that was
treated as a binary string. A binary string is a string of bytes that
has no character set or collation, which differs from a non-binary
character string that has a binary collation. For both types of
strings, comparisons are based on the numeric values of the string
unit, but for non-binary strings the unit is the character and some
character sets allow multi-byte characters.  *Note binary-varbinary::.

The use of `CHARACTER SET binary' in the definition of a *Note `CHAR':
char, *Note `VARCHAR': char, or *Note `TEXT': blob. column causes the
column to be treated as a binary data type. For example, the following
pairs of definitions are equivalent:

     CHAR(10) CHARACTER SET binary
     BINARY(10)

     VARCHAR(10) CHARACTER SET binary
     VARBINARY(10)

     TEXT CHARACTER SET binary
     BLOB


File: manual.info,  Node: charset-binary-collations,  Next: charset-collate-tricky,  Prev: charset-binary-op,  Up: charset-collations

9.1.6.4 The `_bin' and `binary' Collations
..........................................

This section describes how `_bin' collations for non-binary strings
differ from the `binary' `collation' for binary strings.

Non-binary strings (as stored in the *Note `CHAR': char, *Note
`VARCHAR': char, and *Note `TEXT': blob. data types) have a character
set and collation. A given character set can have several collations,
each of which defines a particular sorting and comparison order for the
characters in the set. One of these is the binary collation for the
character set, indicated by a `_bin' suffix in the collation name. For
example, `latin1' and `utf8' have binary collations named `latin1_bin'
and `utf8_bin'.

Binary strings (as stored in the *Note `BINARY': binary-varbinary,
*Note `VARBINARY': binary-varbinary, and *Note `BLOB': blob. data
types) have no character set or collation in the sense that non-binary
strings do. (Applied to a binary string, the `CHARSET()' and
`COLLATION()' functions both return a value of `binary'.) Binary
strings are sequences of bytes and the numeric values of those bytes
determine sort order.

The `_bin' collations differ from the `binary' collation in several
respects.

*The unit for sorting and comparison.* Binary strings are sequences of
bytes.  Sorting and comparison is always based on numeric byte values.
Non-binary strings are sequences of characters, which might be
multi-byte. Collations for non-binary strings define an ordering of the
character values for sorting and comparison.  For the `_bin' collation,
this ordering is based solely on numeric values of the characters
(which is similar to ordering for binary strings except that a `_bin'
collation must take into account that a character might contain
multiple bytes). For other collations, character ordering might take
additional factors such as lettercase into account.

*Character set conversion.* A non-binary string has a character set and
is converted to another character set in many cases, even when the
string has a `_bin' collation:

   * When assigning column values from another column that has a
     different character set:

          UPDATE t1 SET utf8_bin_column=latin1_column;
          INSERT INTO t1 (latin1_column) SELECT utf8_bin_column FROM t2;

   * When assigning column values for *Note `INSERT': insert. or *Note
     `UPDATE': update. using a string literal:

          SET NAMES latin1;
          INSERT INTO t1 (utf8_bin_column) VALUES ('string-in-latin1');

   * When sending results from the server to a client:

          SET NAMES latin1;
          SELECT utf8_bin_column FROM t2;

For binary string columns, no conversion occurs. For the preceding
cases, the string value is copied byte-wise.

*Lettercase conversion.* Collations provide information about
lettercase of characters, so characters in a non-binary string can be
converted from one lettercase to another, even for `_bin' collations
that ignore lettercase for ordering:

     mysql> SET NAMES latin1 COLLATE latin1_bin;
     Query OK, 0 rows affected (0.02 sec)

     mysql> SELECT LOWER('aA'), UPPER('zZ');
     +-------------+-------------+
     | LOWER('aA') | UPPER('zZ') |
     +-------------+-------------+
     | aa          | ZZ          |
     +-------------+-------------+
     1 row in set (0.13 sec)

The concept of lettercase does not apply to bytes in a binary string.
To perform lettercase conversion, the string must be converted to a
non-binary string:

     mysql> SET NAMES binary;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT LOWER('aA'), LOWER(CONVERT('aA' USING latin1));
     +-------------+-----------------------------------+
     | LOWER('aA') | LOWER(CONVERT('aA' USING latin1)) |
     +-------------+-----------------------------------+
     | aA          | aa                                |
     +-------------+-----------------------------------+
     1 row in set (0.00 sec)

*Trailing space handling in comparisons.* Non-binary strings have
`PADSPACE' behavior for all collations, including `_bin' collations.
Trailing spaces are insignificant in comparisons:

     mysql> SET NAMES utf8 COLLATE utf8_bin;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT 'a ' = 'a';
     +------------+
     | 'a ' = 'a' |
     +------------+
     |          1 |
     +------------+
     1 row in set (0.00 sec)

For binary strings, all characters are significant in comparisons,
including trailing spaces:

     mysql> SET NAMES binary;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT 'a ' = 'a';
     +------------+
     | 'a ' = 'a' |
     +------------+
     |          0 |
     +------------+
     1 row in set (0.00 sec)

*Trailing space handling for inserts and retrievals.* `CHAR(N)' columns
store non-binary strings. Values shorter than N characters are extended
with spaces on insertion. For retrieval, trailing spaces are removed.

`BINARY(N)' columns store binary strings. Values shorter than N bytes
are extended with `0x00' bytes on insertion. For retrieval, nothing is
removed; a value of the declared length is always returned.

     mysql> CREATE TABLE t1 (
         ->   a CHAR(10) CHARACTER SET utf8 COLLATE utf8_bin,
         ->   b BINARY(10)
         -> );
     Query OK, 0 rows affected (0.09 sec)

     mysql> INSERT INTO t1 VALUES ('a','a');
     Query OK, 1 row affected (0.01 sec)

     mysql> SELECT HEX(a), HEX(b) FROM t1;
     +--------+----------------------+
     | HEX(a) | HEX(b)               |
     +--------+----------------------+
     | 61     | 61000000000000000000 |
     +--------+----------------------+
     1 row in set (0.04 sec)


File: manual.info,  Node: charset-collate-tricky,  Next: charset-collation-charset,  Prev: charset-binary-collations,  Up: charset-collations

9.1.6.5 Special Cases Where Collation Determination Is Tricky
.............................................................

In the great majority of statements, it is obvious what collation MySQL
uses to resolve a comparison operation. For example, in the following
cases, it should be clear that the collation is the collation of column
`x':

     SELECT x FROM T ORDER BY x;
     SELECT x FROM T WHERE x = x;
     SELECT DISTINCT x FROM T;

However, when multiple operands are involved, there can be ambiguity.
For example:

     SELECT x FROM T WHERE x = 'Y';

Should this query use the collation of the column `x', or of the string
literal `'Y''?

Standard SQL resolves such questions using what used to be called
`coercibility' rules. Basically, this means: Both `x' and `'Y'' have
collations, so which collation takes precedence? This can be difficult
to resolve, but the following rules cover most situations:

   * An explicit `COLLATE' clause has a coercibility of 0. (Not
     coercible at all.)

   * The concatenation of two strings with different collations has a
     coercibility of 1.

   * The collation of a column or a stored routine parameter or local
     variable has a coercibility of 2.

   * A `system constant' (the string returned by functions such as
     `USER()' or `VERSION()') has a coercibility of 3.

   * A literal's collation has a coercibility of 4.

   * `NULL' or an expression that is derived from `NULL' has a
     coercibility of 5.

The preceding coercibility values are current for MySQL 6.0.

Those rules resolve ambiguities in the following manner:

   * Use the collation with the lowest coercibility value.

   * If both sides have the same coercibility, then:

        * If both sides are Unicode, or both sides are not Unicode, it
          is an error.

        * If one of the sides has a Unicode character set, and another
          side has a non-Unicode character set, the side with Unicode
          character set wins, and automatic character set conversion is
          applied to the non-Unicode side. For example, the following
          statement will not return an error:

               SELECT CONCAT(utf8_column, latin1_column) FROM t1;

          It will return a result, and the character set of the result
          will be `utf8'. The collation of the result will be the
          collation of `utf8_column'. Values of `latin1_column' will be
          automatically converted to `utf8' before concatenating.

        * For an operation with operands from the same character set
          but that mix a `_bin' collation and a `_ci' or `_cs'
          collation, the `_bin' collation is used. This is similar to
          how operations that mix non-binary and binary strings
          evaluate the operands as binary strings, except that it is
          for collations rather than data types.

Although automatic conversion is not in the SQL standard, the SQL
standard document does say that every character set is (in terms of
supported characters) a `subset' of Unicode. Because it is a well-known
principle that `what applies to a superset can apply to a subset,' we
believe that a collation for Unicode can apply for comparisons with
non-Unicode strings.

Examples:

`column1 = 'A''                      Use collation of `column1'
`column1 = 'A' COLLATE x'            Use collation of `'A' COLLATE x'
`column1 COLLATE x = 'A' COLLATE y'  Error

The `COERCIBILITY()' function can be used to determine the coercibility
of a string expression:

     mysql> SELECT COERCIBILITY('A' COLLATE latin1_swedish_ci);
             -> 0
     mysql> SELECT COERCIBILITY(VERSION());
             -> 3
     mysql> SELECT COERCIBILITY('A');
             -> 4

See *Note information-functions::.


File: manual.info,  Node: charset-collation-charset,  Next: charset-collation-effect,  Prev: charset-collate-tricky,  Up: charset-collations

9.1.6.6 Collations Must Be for the Right Character Set
......................................................

Each character set has one or more collations, but each collation is
associated with one and only one character set.  Therefore, the
following statement causes an error message because the `latin2_bin'
collation is not legal with the `latin1' character set:

     mysql> SELECT _latin1 'x' COLLATE latin2_bin;
     ERROR 1253 (42000): COLLATION 'latin2_bin' is not valid
     for CHARACTER SET 'latin1'


File: manual.info,  Node: charset-collation-effect,  Prev: charset-collation-charset,  Up: charset-collations

9.1.6.7 Examples of the Effect of Collation
...........................................

*Example 1: Sorting German Umlauts*

Suppose that column `X' in table `T' has these `latin1' column values:

     Muffler
     Mu"ller
     MX Systems
     MySQL

Suppose also that the column values are retrieved using the following
statement:

     SELECT X FROM T ORDER BY X COLLATE COLLATION_NAME;

The following table shows the resulting order of the values if we use
`ORDER BY' with different collations.

`latin1_swedish_ci'    `latin1_german1_ci'    `latin1_german2_ci'
Muffler                Muffler                Mu"ller
MX Systems             Mu"ller                Muffler
Mu"ller                MX Systems             MX Systems
MySQL                  MySQL                  MySQL

The character that causes the different sort orders in this example is
the U with two dots over it (`u"'), which the Germans call `U-umlaut.'

   * The first column shows the result of the *Note `SELECT': select.
     using the Swedish/Finnish collating rule, which says that U-umlaut
     sorts with Y.

   * The second column shows the result of the *Note `SELECT': select.
     using the German DIN-1 rule, which says that U-umlaut sorts with U.

   * The third column shows the result of the *Note `SELECT': select.
     using the German DIN-2 rule, which says that U-umlaut sorts with
     UE.

*Example 2: Searching for German Umlauts*

Suppose that you have three tables that differ only by the character
set and collation used:

     mysql> CREATE TABLE german1 (
         ->   c CHAR(10)
         -> ) CHARACTER SET latin1 COLLATE latin1_german1_ci;
     mysql> CREATE TABLE german2 (
         ->   c CHAR(10)
         -> ) CHARACTER SET latin1 COLLATE latin1_german2_ci;
     mysql> CREATE TABLE germanutf8 (
         ->   c CHAR(10)
         -> ) CHARACTER SET utf8 COLLATE utf8_unicode_ci;

Each table contains two records:

     mysql> INSERT INTO german1 VALUES ('Bar'), ('Ba"r');
     mysql> INSERT INTO german2 VALUES ('Bar'), ('Ba"r');
     mysql> INSERT INTO germanutf8 VALUES ('Bar'), ('Ba"r');

Two of the above collations have an `A = A"' equality, and one has no
such equality (`latin1_german2_ci'). For that reason, you'll get these
results in comparisons:

     mysql> SELECT * FROM german1 WHERE c = 'Ba"r';
     +------+
     | c    |
     +------+
     | Bar  |
     | Ba"r  |
     +------+
     mysql> SELECT * FROM german2 WHERE c = 'Ba"r';
     +------+
     | c    |
     +------+
     | Ba"r  |
     +------+
     mysql> SELECT * FROM germanutf8 WHERE c = 'Ba"r';
     +------+
     | c    |
     +------+
     | Bar  |
     | Ba"r  |
     +------+

This is not a bug but rather a consequence of the sorting that
`latin1_german1_ci' or `utf8_unicode_ci' do (the sorting shown is done
according to the German DIN 5007 standard).


File: manual.info,  Node: charset-repertoire,  Next: charset-operations,  Prev: charset-collations,  Up: charset

9.1.7 String Repertoire
-----------------------

The _repertoire_ of a character set is the collection of characters in
the set.

String expressions have a repertoire attribute, which can have two
values:

   * `ASCII': The expression can contain only characters in the Unicode
     range `U+0000' to `U+007F'.

   * `UNICODE': The expression can contain characters in the Unicode
     range `U+0000' to `U+FFFF'.

The `ASCII' range is a subset of `UNICODE' range, so a string with
`ASCII' repertoire can be converted safely without loss of information
to the character set of any string with `UNICODE' repertoire or to a
character set that is a superset of `ASCII'. (All MySQL character sets
are supersets of `ASCII' with the exception of `swe7', which reuses some
punctuation characters for Swedish accented characters.) The use of
repertoire enables character set conversion in expressions for many
cases where MySQL would otherwise return an `illegal mix of collations'
error.

The following discussion provides examples of expressions and their
repertoires, and describes how the use of repertoire changes string
expression evaluation:

   * The repertoire for string constants depends on string content:

          SET NAMES utf8; SELECT 'abc';
          SELECT _utf8'def';
          SELECT N'MySQL';

     Although the character set is `utf8' in each of the preceding
     cases, the strings do not actually contain any characters outside
     the ASCII range, so their repertoire is `ASCII' rather than
     `UNICODE'.

   * Columns having the `ascii' character set have `ASCII' repertoire
     because of their character set. In the following table, `c1' has
     `ASCII' repertoire:

          CREATE TABLE t1 (c1 CHAR(1) CHARACTER SET ascii);

     The following example illustrates how repertoire enables a result
     to be determined in a case where an error occurs without
     repertoire:

          CREATE TABLE t1 (
            c1 CHAR(1) CHARACTER SET latin1,
            c2 CHAR(1) CHARACTER SET ascii
          );
          INSERT INTO t1 VALUES ('a','b');
          SELECT CONCAT(c1,c2) FROM t1;

     Without repertoire, this error occurs:

          ERROR 1267 (HY000): Illegal mix of collations (latin1_swedish_ci,IMPLICIT)
          and (ascii_general_ci,IMPLICIT) for operation 'concat'

     Using repertoire, subset to superset (`ascii' to `latin1')
     conversion can occur and a result is returned:

          +---------------+
          | CONCAT(c1,c2) |
          +---------------+
          | ab            |
          +---------------+

   * Functions with one string argument inherit the repertoire of their
     argument. The result of `UPPER(_utf8'ABC')' has `ASCII'
     repertoire, because its argument has `ASCII' repertoire.

   * For functions that return a string but do not have string
     arguments and use `character_set_connection' as the result
     character set, the result repertoire is `ASCII' if
     `character_set_connection' is `ascii', and `UNICODE' otherwise:

          FORMAT(NUMERIC_COLUMN, 4);

     Use of repertoire changes how MySQL evaluates the following
     example:

          SET NAMES ascii;
          CREATE TABLE t1 (a INT, b VARCHAR(10) CHARACTER SET latin1);
          INSERT INTO t1 VALUES (1,'b');
          SELECT CONCAT(FORMAT(a, 4), b) FROM t1;

     Without repertoire, this error occurs:

          ERROR 1267 (HY000): Illegal mix of collations (ascii_general_ci,COERCIBLE)
          and (latin1_swedish_ci,IMPLICIT) for operation 'concat'

     With repertoire, a result is returned:

          +-------------------------+
          | CONCAT(FORMAT(a, 4), b) |
          +-------------------------+
          | 1.0000b                 |
          +-------------------------+

   * Functions with two or more string arguments use the `widest'
     argument repertoire for the result repertoire (`UNICODE' is wider
     than `ASCII'). Consider the following `CONCAT()' calls:

          CONCAT(_ucs2 0x0041, _ucs2 0x0042)
          CONCAT(_ucs2 0x0041, _ucs2 0x00C2)

     For the first call, the repertoire is `ASCII' because both
     arguments are within the range of the `ascii' character set. For
     the second call, the repertoire is `UNICODE' because the second
     argument is outside the `ascii' character set range.

   * The repertoire for function return values is determined based only
     on the repertoire of the arguments that affect the result's
     character set and collation.

          IF(column1 < column2, 'smaller', 'greater')

     The result repertoire is `ASCII' because the two string arguments
     (the second argument and the third argument) both have `ASCII'
     repertoire. The first argument does not matter for the result
     repertoire, even if the expression uses string values.


File: manual.info,  Node: charset-operations,  Next: charset-unicode,  Prev: charset-repertoire,  Up: charset

9.1.8 Operations Affected by Character Set Support
--------------------------------------------------

* Menu:

* charset-result::               Result Strings
* charset-convert::              `CONVERT()' and `CAST()'
* charset-show::                 `SHOW' Statements and `INFORMATION_SCHEMA'

This section describes operations that take character set information
into account.


File: manual.info,  Node: charset-result,  Next: charset-convert,  Prev: charset-operations,  Up: charset-operations

9.1.8.1 Result Strings
......................

MySQL has many operators and functions that return a string.  This
section answers the question: What is the character set and collation
of such a string?

For simple functions that take string input and return a string result
as output, the output's character set and collation are the same as
those of the principal input value.  For example, `UPPER(X)' returns a
string whose character string and collation are the same as that of X.
The same applies for `INSTR()', `LCASE()', `LOWER()', `LTRIM()',
`MID()', `REPEAT()', `REPLACE()', `REVERSE()', `RIGHT()', `RPAD()',
`RTRIM()', `SOUNDEX()', `SUBSTRING()', `TRIM()', `UCASE()', and
`UPPER()'.

Note: The `REPLACE()' function, unlike all other functions, always
ignores the collation of the string input and performs a case-sensitive
comparison.

If a string input or function result is a binary string, the string has
no character set or collation. This can be checked by using the
`CHARSET()' and `COLLATION()' functions, both of which return `binary'
to indicate that their argument is a binary string:

     mysql> SELECT CHARSET(BINARY 'a'), COLLATION(BINARY 'a');
     +---------------------+-----------------------+
     | CHARSET(BINARY 'a') | COLLATION(BINARY 'a') |
     +---------------------+-----------------------+
     | binary              | binary                |
     +---------------------+-----------------------+

For operations that combine multiple string inputs and return a single
string output, the `aggregation rules' of standard SQL apply for
determining the collation of the result:

   * If an explicit `COLLATE X' occurs, use X.

   * If explicit `COLLATE X' and `COLLATE Y' occur, raise an error.

   * Otherwise, if all collations are X, use X.

   * Otherwise, the result has no collation.

For example, with `CASE ... WHEN a THEN b WHEN b THEN c COLLATE X END',
the resulting collation is X. The same applies for *Note `UNION': union,
`||', `CONCAT()', `ELT()', `GREATEST()', `IF()', and `LEAST()'.

For operations that convert to character data, the character set and
collation of the strings that result from the operations are defined by
the `character_set_connection' and `collation_connection' system
variables. This applies only to `CAST()', `CONV()', `FORMAT()',
`HEX()', and `SPACE()'.

If you are uncertain about the character set or collation of the result
returned by a string function, you can use the `CHARSET()' or
`COLLATION()' function to find out:

     mysql> SELECT USER(), CHARSET(USER()), COLLATION(USER());
     +----------------+-----------------+-------------------+
     | USER()         | CHARSET(USER()) | COLLATION(USER()) |
     +----------------+-----------------+-------------------+
     | test@localhost | utf8            | utf8_general_ci   |
     +----------------+-----------------+-------------------+


File: manual.info,  Node: charset-convert,  Next: charset-show,  Prev: charset-result,  Up: charset-operations

9.1.8.2 `CONVERT()' and `CAST()'
................................

`CONVERT()' provides a way to convert data between different character
sets. The syntax is:

     CONVERT(EXPR USING TRANSCODING_NAME)

In MySQL, transcoding names are the same as the corresponding character
set names.

Examples:

     SELECT CONVERT(_latin1'Mu"ller' USING utf8);
     INSERT INTO utf8table (utf8column)
         SELECT CONVERT(latin1field USING utf8) FROM latin1table;

`CONVERT(... USING ...)' is implemented according to the standard SQL
specification.

You may also use `CAST()' to convert a string to a different character
set. The syntax is:

     CAST(CHARACTER_STRING AS CHARACTER_DATA_TYPE CHARACTER SET CHARSET_NAME)

Example:

     SELECT CAST(_latin1'test' AS CHAR CHARACTER SET utf8);

If you use `CAST()' without specifying `CHARACTER SET', the resulting
character set and collation are defined by the
`character_set_connection' and `collation_connection' system variables.
If you use `CAST()' with `CHARACTER SET X', the resulting character set
and collation are `X' and the default collation of `X'.

You may not use a `COLLATE' clause inside a `CAST()', but you may use it
outside. That is, `CAST(... COLLATE ...)' is illegal, but `CAST(...)
COLLATE ...' is legal.

Example:

     SELECT CAST(_latin1'test' AS CHAR CHARACTER SET utf8) COLLATE utf8_bin;


File: manual.info,  Node: charset-show,  Prev: charset-convert,  Up: charset-operations

9.1.8.3 `SHOW' Statements and `INFORMATION_SCHEMA'
..................................................

Several *Note `SHOW': show. statements provide additional character set
information. These include *Note `SHOW CHARACTER SET':
show-character-set, *Note `SHOW COLLATION': show-collation, *Note `SHOW
CREATE DATABASE': show-create-database, *Note `SHOW CREATE TABLE':
show-create-table. and *Note `SHOW COLUMNS': show-columns. These
statements are described here briefly. For more information, see *Note
show::.

`INFORMATION_SCHEMA' has several tables that contain information
similar to that displayed by the *Note `SHOW': show. statements. For
example, the *Note `CHARACTER_SETS': character-sets-table. and *Note
`COLLATIONS': collations-table. tables contain the information
displayed by *Note `SHOW CHARACTER SET': show-character-set. and *Note
`SHOW COLLATION': show-collation. See *Note information-schema::.

The *Note `SHOW CHARACTER SET': show-character-set. command shows all
available character sets. It takes an optional `LIKE' clause that
indicates which character set names to match. For example:

     mysql> SHOW CHARACTER SET LIKE 'latin%';
     +---------+-----------------------------+-------------------+--------+
     | Charset | Description                 | Default collation | Maxlen |
     +---------+-----------------------------+-------------------+--------+
     | latin1  | cp1252 West European        | latin1_swedish_ci |      1 |
     | latin2  | ISO 8859-2 Central European | latin2_general_ci |      1 |
     | latin5  | ISO 8859-9 Turkish          | latin5_turkish_ci |      1 |
     | latin7  | ISO 8859-13 Baltic          | latin7_general_ci |      1 |
     +---------+-----------------------------+-------------------+--------+

The output from *Note `SHOW COLLATION': show-collation.  includes all
available character sets. It takes an optional `LIKE' clause that
indicates which collation names to match. For example:

     mysql> SHOW COLLATION LIKE 'latin1%';
     +-------------------+---------+----+---------+----------+---------+
     | Collation         | Charset | Id | Default | Compiled | Sortlen |
     +-------------------+---------+----+---------+----------+---------+
     | latin1_german1_ci | latin1  |  5 |         |          |       0 |
     | latin1_swedish_ci | latin1  |  8 | Yes     | Yes      |       0 |
     | latin1_danish_ci  | latin1  | 15 |         |          |       0 |
     | latin1_german2_ci | latin1  | 31 |         | Yes      |       2 |
     | latin1_bin        | latin1  | 47 |         | Yes      |       0 |
     | latin1_general_ci | latin1  | 48 |         |          |       0 |
     | latin1_general_cs | latin1  | 49 |         |          |       0 |
     | latin1_spanish_ci | latin1  | 94 |         |          |       0 |
     +-------------------+---------+----+---------+----------+---------+

*Note `SHOW CREATE DATABASE': show-create-database. displays the *Note
`CREATE DATABASE': create-database. statement that creates a given
database:

     mysql> SHOW CREATE DATABASE test;
     +----------+-----------------------------------------------------------------+
     | Database | Create Database                                                 |
     +----------+-----------------------------------------------------------------+
     | test     | CREATE DATABASE `test` /*!40100 DEFAULT CHARACTER SET latin1 */ |
     +----------+-----------------------------------------------------------------+

If no `COLLATE' clause is shown, the default collation for the
character set applies.

*Note `SHOW CREATE TABLE': show-create-table. is similar, but displays
the *Note `CREATE TABLE': create-table.  statement to create a given
table. The column definitions indicate any character set
specifications, and the table options include character set information.

The *Note `SHOW COLUMNS': show-columns. statement displays the
collations of a table's columns when invoked as *Note `SHOW FULL
COLUMNS': show-columns. Columns with *Note `CHAR': char, *Note
`VARCHAR': char, or *Note `TEXT': blob. data types have collations.
Numeric and other non-character types have no collation (indicated by
`NULL' as the `Collation' value). For example:

     mysql> SHOW FULL COLUMNS FROM person\G
     *************************** 1. row ***************************
          Field: id
           Type: smallint(5) unsigned
      Collation: NULL
           Null: NO
            Key: PRI
        Default: NULL
          Extra: auto_increment
     Privileges: select,insert,update,references
        Comment:
     *************************** 2. row ***************************
          Field: name
           Type: char(60)
      Collation: latin1_swedish_ci
           Null: NO
            Key:
        Default:
          Extra:
     Privileges: select,insert,update,references
        Comment:

The character set is not part of the display but is implied by the
collation name.


File: manual.info,  Node: charset-unicode,  Next: charset-unicode-upgrading,  Prev: charset-operations,  Up: charset

9.1.9 Unicode Support
---------------------

The initial implementation of Unicode support (in MySQL 4.1) included
two character sets for storing Unicode data:

   * `ucs2', the UCS-2 encoding of the Unicode character set using 16
     bits per character

   * `utf8', a UTF-8 encoding of the Unicode character set using one to
     three bytes per character

These two character sets support the characters from the Basic
Multilingual Plane (BMP) of Unicode Version 3.0. BMP characters have
these characteristics:

   * Their code values are between 0 and 65535 (or `U+0000' .. `U+FFFF')

   * They can be encoded with a fixed 16-bit word, as in `ucs2'

   * They can be encoded with 8, 16, or 24 bits, as in `utf8'

   * They are sufficient for almost all characters in major languages

Characters not supported by the aforementioned character sets include
supplementary characters that lie outside the BMP. As of MySQL 6.0
(versions 6.0.4 and up), Unicode support is extended to include
supplementary characters, which requires new character sets that have a
broader range and therefore take more space. The following table shows
a brief feature comparison of previous and current Unicode support.

*Before MySQL 6.0*                   *MySQL 6.0*
All Unicode 3.0 characters           All Unicode 5.0 characters
No supplementary characters          With supplementary characters
`ucs2' character set                 No change
`utf8' character set for up to       Renamed to `utf8mb3'
three bytes                          
                                     New `utf8' character set for up to
                                     four bytes
                                     New `utf16' character set
                                     New `utf32' character set

Most of these changes are upward compatible. For example, the old
`utf8' character set (the three-byte version) has been renamed to
`utf8mb3', so tables created before MySQL 6.0 that used `utf8' are
treated as using `utf8mb3' after an in-place upgrade to MySQL 6.0.
However, the table contents will not have changed in any way.

The new `utf8' character set, as well as `utf16' and `utf32', support
supplementary characters. The Unicode character sets in MySQL 6.0 are:

   * `ucs2', the UCS-2 encoding of the Unicode character set using 16
     bits per character

   * `utf16', the UTF-16 encoding for the Unicode character set; like
     `ucs2' but with an extension for supplementary characters

   * `utf32', the UTF-32 encoding for the Unicode character set using
     32 bits per character

   * `utf8', a UTF-8 encoding of the Unicode character set using one to
     four bytes per character

   * `utf8mb3', a UTF-8 encoding of the Unicode character set using one
     to three bytes per character (known as `utf8' before MySQL 6.0)

A similar set of collations is available for each Unicode character
set. For example, each has a Danish collation, the names of which are
`ucs2_danish_ci', `utf16_danish_ci', `ucs32_danish_ci',
`utf8_danish_ci', and `utf8mb3_danish_ci'. All Unicode collations are
listed at *Note charset-unicode-sets::, which also describes collation
properties for supplementary characters.

Note that although many of the supplementary characters come from East
Asian languages, what MySQL 6.0 adds is support for more Japanese and
Chinese characters in Unicode character sets, not support for new
Japanese and Chinese character sets.

The following discussion provides additional detail on the Unicode
character sets in MySQL. For details on potential incompatibility
issues for your applications, see *Note charset-unicode-upgrading::.
That section also describes how to convert tables from `utf8mb3' to the
new (four-byte) `utf8' character set, and what constraints may apply in
doing so.

The MySQL implementation of UCS-2, UTF-16, and UTF-32 stores characters
in big-endian byte order and does not use a byte order mark (BOM) at
the beginning of values. Other database systems might use little-endian
byte order or a BOM, in which case, conversion of values will need to
be performed when transferring data between those systems and MySQL.

MySQL uses no BOM for UTF-8 values.

Client applications that need to communicate with the server using
Unicode should set the client character set accordingly; for example,
by issuing a `SET NAMES 'utf8'' statement. `ucs2', `utf16', and `utf32'
cannot be used as a client character set, which means that they do not
work for `SET NAMES' or `SET CHARACTER SET'. (See *Note
charset-connection::.)

*The `ucs2' Character Set (UCS-2 Unicode Encoding)*

In UCS-2, every character is represented by a two-byte Unicode code
with the most significant byte first. For example: `LATIN CAPITAL
LETTER A' has the code `0x0041' and it is stored as a two-byte
sequence: `0x00 0x41'. `CYRILLIC SMALL LETTER YERU' (Unicode `0x044B')
is stored as a two-byte sequence: `0x04 0x4B'. For Unicode characters
and their codes, please refer to the Unicode Home Page
(http://www.unicode.org/).

In MySQL, the `ucs2' character set is a fixed 16-bit encoding for
Unicode BMP characters.

*The `utf16' Character Set (UTF-16 Unicode Encoding)*

The `utf16' character set is the `ucs2' character set with an extension
that enables encoding of supplementary characters:

   * For a BMP character, `utf16' and `ucs2' have identical storage
     characteristics: The same code values, same encoding, and same
     length.

   * For a supplementary character, `utf16' has a special sequence for
     representing the character using 32 bits. This is called the
     `surrogate' mechanism: For a number greater than `0xffff', take 10
     bits and add them to `0xd800' and put them in the first 16-bit
     word, take 10 more bits and add them to `0xdc00' and put them in
     the next 16-bit word. Consequently, all supplementary characters
     require 32 bits, where the first 16 bits are a number between
     `0xd800' and `0xdbff', and the last 16 bits are a number between
     `0xdc00' and `0xdfff'.  Examples are in 15.5 Surrogates Area
     (http://unicode.org/versions/Unicode4.0.0/ch15.pdf) in the Unicode
     4.0 document.

Because `utf16' supports surrogates and `ucs2' does not, there is a
validity check that applies only in `utf16': You cannot insert a top
surrogate without a bottom surrogate, or vice versa. For example:

     INSERT INTO t (ucs2_column) VALUES (0xd800); /* legal */
     INSERT INTO t (utf16_column)VALUES (0xd800); /* illegal */

There is no validity check for characters that are technically valid
but are not true Unicode (that is, characters that Unicode considers to
be `unassigned code points' or `private use' characters or even
`illegals' like `0xffff'). For example, since `U+F8FF' is the Apple
Logo, this is legal:

     INSERT INTO t (utf16_column)VALUES (0xf8ff); /* legal */

Such characters cannot be expected to mean the same thing to everyone.

Because MySQL must allow for the worst case (that one character
requires four bytes) the maximum length of a `utf16' column or index is
only half of the maximum length for a `ucs2' column or index.  For
example, at the time of writing the maximum length of a Falcon index
key is 1100 bytes (assuming the default Falcon page size), so these
statements create tables with the longest allowed indexes for `ucs2' and
`utf16' columns:

     CREATE TABLE tf (s1 VARCHAR(550) CHARACTER SET ucs2) ENGINE=FALCON;
     CREATE INDEX i ON tf (s1);
     CREATE TABLE tg (s1 VARCHAR(275) CHARACTER SET utf16) ENGINE=FALCON;
     CREATE INDEX i ON tg (s1);

*The `utf32' Character Set (UTF-32 Unicode Encoding)*

The `utf32' character set is fixed length (like `ucs2' and unlike
`utf16').  `utf32' uses 32 bits for every character, unlike `ucs2'
(which uses 16 bits for every character), and unlike `utf16' (which
uses 16 bits for some characters and 32 bits for others).

`utf32' takes twice as much space as `ucs2' and more space than
`utf16', but `utf32' has the same advantage as `ucs2' that it is
predictable for storage: The required number of bytes for `utf32'
equals the number of characters times 4. Also, unlike `utf16', there
are no tricks for encoding in `utf32', so the stored value equals the
code value.

To demonstrate how the latter advantage is useful, here is an example
that shows how to determine a `utf8' value given the `utf32' code value:

     /* Assume code value = 100cc LINEAR B WHEELED CHARIOT */
     CREATE TABLE tmp (utf32 CHAR(1) CHARACTER SET utf32,
                       utf8 CHAR(1) CHARACTER SET utf8);
     INSERT INTO tmp VALUES (0x000100cc,NULL);
     UPDATE tmp SET utf8 = utf32;
     SELECT HEX(utf32),HEX(utf8) FROM tmp;

MySQL is very forgiving about additions of unassigned Unicode
characters, private-use-area characters, and other code values not
present in the official Unicode 5.0 Character Database
(http://www.unicode.org/Public/UNIDATA/UnicodeData.txt). There is in
fact only one validity check for `utf32': No code value may be greater
than `0x10ffff'. For example, this is illegal:

     INSERT INTO t (utf32_column) VALUES (0x110000); /* illegal */

*The `utf8' Character Set (Four-Byte UTF-8 Unicode Encoding)*

UTF-8 (Unicode Transformation Format with 8-bit units) is an
alternative way to store Unicode data. It is implemented according to
RFC 3629. RFC 3629 describes encoding sequences that take from one to
four bytes. (An older standard for UTF-8 encoding is given by RFC 2279,
which describes UTF-8 sequences that take from one to six bytes. RFC
3629 renders RFC 2279 obsolete; for this reason, sequences with five
and six bytes are no longer used.)

The idea of UTF-8 is that various Unicode characters are encoded using
byte sequences of different lengths:

   * Basic Latin letters, digits, and punctuation signs use one byte.

   * Most European and Middle East script letters fit into a two-byte
     sequence: extended Latin letters (with tilde, macron, acute, grave
     and other accents), Cyrillic, Greek, Armenian, Hebrew, Arabic,
     Syriac, and others.

   * Korean, Chinese, and Japanese ideographs use three-byte or
     four-byte sequences.

*Tip*: To save space with UTF-8, use *Note `VARCHAR': char. instead of
*Note `CHAR': char. Otherwise, MySQL must reserve four bytes for each
character in a `CHAR CHARACTER SET utf8' column because that is the
maximum possible length. For example, MySQL must reserve 40 bytes for a
`CHAR(10) CHARACTER SET utf8' column.

Before MySQL 6.0, the character set named `utf8' contained only BMP
characters and used a maximum of three bytes per character. As of MySQL
6.0, that character set uses a different name, `utf8mb3', but its
characteristics remain the same as before.

In terms of table content (for old tables created before MySQL 6.0),
the old `utf8' (now `utf8mb3)') and new `utf8' are compatible:

   * For a BMP character, the 5.1 and 6.0 versions of `utf8' have
     identical storage characteristics: same code values, same
     encoding, same length.

   * For a supplementary character, `utf8' in 5.1 cannot store the
     character at all, while `utf8' in 6.0 requires four bytes to store.
     Since `utf8' in 5.1 cannot store the character at all, you do not
     have any supplementary characters in `utf8' columns in your 5.1
     database, so you need not worry about converting characters or
     losing data.

*The `utf8mb3' Character Set (Three-Byte UTF-8 Unicode Encoding)*

The `utf8mb3' character set in MySQL 6.0 is the same as the character
set that was called `utf8' before 6.0. In other words, `utf8mb3' in
MySQL 6.0 has exactly the same characteristics as `utf8' in MySQL 5.1:

   * No support for supplementary characters (BMP characters only)

   * Maximum of three bytes per multi-byte character

For the few cases where it is desirable to have complete compatibility
in MySQL 6.0 with the old `utf8' character set, you can define with
`CHARACTER SET utf8mb3'.

Exactly the same set of characters is available in `utf8mb3' as in
`ucs2'. That is, they have the same repertoire.


File: manual.info,  Node: charset-unicode-upgrading,  Next: charset-metadata,  Prev: charset-unicode,  Up: charset

9.1.10 Upgrading from Previous to Current Unicode Support
---------------------------------------------------------

This section describes issues pertaining to Unicode support that you
may face when upgrading from MySQL 5.1 to 6.0. It also provides
guidelines for downgrading from 6.0 back to 5.1.

In most respects, upgrading from MySQL 5.1 to 6.0 should present few
problems with regard to Unicode usage, although there are some
potential areas of incompatibility. Some examples:

   * For the variable-length character data types (*Note `VARCHAR':
     char. and the *Note `TEXT': blob. types), the maximum length in
     characters for `utf8' columns is less in MySQL 6.0 than previously.

   * For all character data types (*Note `CHAR': char, *Note `VARCHAR':
     char, and the *Note `TEXT': blob. types), the maximum number of
     characters for `utf8' columns that can be indexed is less in MySQL
     6.0 than previously.

Consequently, if you want to upgrade tables from the old `utf8' (now
`utf8mb3') to the current `utf8', it may be necessary to change some
column or index definitions.

You can upgrade from MySQL 5.1 to 6.0 in two different ways:

   * You can install 6.0 `in place' on top of an existing 5.1
     installation. In this case, the names of `utf8' character sets and
     collations will change to use `utf8mb3', but no changes to column
     or index lengths in table definitions will be needed.  That is,
     there will be name differences but no structural changes.

   * You can dump your 5.1 data using *Note `mysqldump': mysqldump, and
     then reload the dump into 6.0. Because definitions in the dump
     file will refer to `utf8', the server will use `utf8' in the
     reloaded tables, but these tables will use the new (four-byte)
     `utf8', not the old 5.1 (three-byte) `utf8'. In this case, the
     names of `utf8' character sets and collations will remain the
     same, but changes to column or index lengths might be needed for
     long columns. In other words, there will not be name differences,
     but you might need to make some structural changes.

If you upgrade MySQL in place by installing 6.0 on top of an existing
5.1 installation, the changes in the 6.0 Unicode implementation have
these effects:

   * For `ucs2', there should be no issues

   * Database and tables that used `utf8' in MySQL 5.1 will be reported
     as using `utf8mb3' in 6.0 (for example, if you examine object
     structure with *Note `SHOW': show. statements or select
     definitions from `INFORMATION_SCHEMA' tables). However, no data
     will have been changed and the server can use `utf8mb3' columns and
     indexes with no conversion required.

   * When the server starts, it checks the structure of certain system
     tables in the `mysql' database. If it finds that columns have the
     `utf8mb3' character set when it expects `utf8', it writes warnings
     to the error log but continues to use the tables. To make the
     warnings go away, convert the system tables to `utf8' by running
     *Note `mysql_upgrade': mysql-upgrade.

If you use events, a known issue is that if you upgrade from MySQL 5.1
to 6.0.4 though 6.0.6, the event scheduler will not work, even after
you run *Note `mysql_upgrade': mysql-upgrade. (This is an issue only
for an upgrade, not for a new installation of MySQL 6.0.x.) As of MySQL
6.0.7, *Note `mysql_upgrade': mysql-upgrade. handles upgrading the
system tables properly. If you upgrade to 6.0.4 through 6.0.6, you can
work around this upgrading problem by using these instructions:

  1. In MySQL 5.1, before upgrading, create a dump file containing your
     `mysql.event' table:

          shell> mysqldump -uroot -p mysql event > event.sql

  2. Stop the server, upgrade to MySQL 6.0, and start the server.

  3. Recreate the `mysql.event' table using the dump file:

          shell> mysql -uroot -p mysql < event.sql

  4. Run *Note `mysql_upgrade': mysql-upgrade. to upgrade the other
     system tables in the `mysql' database:

          shell> mysql_upgrade -uroot -p

  5. Restart the server. The event scheduler should run normally.

To following example illustrates what you should see if you use MySQL
5.1 tables with an installation that has been upgraded in place to 6.0.
Suppose that a table was originally defined as follows in MySQL 5.1:

     CREATE TABLE t1 (
       col1 CHAR(10) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
       col2 CHAR(10) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL
     ) CHARACTER SET utf8;

In MySQL 5.1, *Note `SHOW CREATE TABLE': show-create-table.  produces
this result:

     mysql> SHOW CREATE TABLE t1\G
     *************************** 1. row ***************************
            Table: t1
     Create Table: CREATE TABLE `t1` (
       `col1` char(10) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
       `col2` char(10) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL
     ) ENGINE=MyISAM DEFAULT CHARSET=utf8

After upgrading to MySQL 6.0, *Note `SHOW CREATE TABLE':
show-create-table. produces this result instead:

     mysql> SHOW CREATE TABLE t1\G
     *************************** 1. row ***************************
            Table: t1
     Create Table: CREATE TABLE `t1` (
       `col1` char(10) CHARACTER SET utf8mb3 COLLATE utf8mb3_unicode_ci NOT NULL,
       `col2` char(10) CHARACTER SET utf8mb3 COLLATE utf8mb3_bin NOT NULL
     ) ENGINE=MyISAM DEFAULT CHARSET=utf8mb3

Internally, the IDs for the character data have not changed.  Only the
names associated with the IDs have changed. For example, in MySQL 5.1,
we have this:

     mysql> SHOW COLLATION LIKE 'utf8%bin';
     +-----------+---------+----+---------+----------+---------+
     | Collation | Charset | Id | Default | Compiled | Sortlen |
     +-----------+---------+----+---------+----------+---------+
     | utf8_bin  | utf8    | 83 |         | Yes      |       1 |
     +-----------+---------+----+---------+----------+---------+

In MySQL 6.0, we have this:

     mysql> SHOW COLLATION LIKE 'utf8%bin';
     +-------------+---------+----+---------+----------+---------+
     | Collation   | Charset | Id | Default | Compiled | Sortlen |
     +-------------+---------+----+---------+----------+---------+
     | utf8mb3_bin | utf8mb3 | 83 |         | Yes      |       1 |
     | utf8_bin    | utf8    | 46 |         | Yes      |       1 |
     +-------------+---------+----+---------+----------+---------+

Thus, for table `t1', the columnn `col2' still has a collation ID of
83. What has changed is the name associated with 83. In other words, the
collation IDs for the old `utf8' character set now belong to `utf8mb3'.
The collations IDs for the new `utf8' character set are new.

Tables can be converted from `utf8mb3' to `utf8' by using *Note `ALTER
TABLE': alter-table. The following statement does so for `t1':

     ALTER TABLE t1
       DEFAULT CHARACTER SET utf8,
       MODIFY col1 CHAR(10) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
       MODIFY col2 CHAR(10) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL;

In terms of table content, conversion from the old `utf8' to the new
`utf8' presents no problems:

   * For a BMP character, the 5.1 and 6.0 versions of `utf8' have
     identical storage characteristics: same code values, same
     encoding, same length.

   * For a supplementary character, `utf8' in 5.1 cannot store the
     character at all, while `utf8' in 6.0 requires four bytes to store.
     Since `utf8' in 5.1 cannot store the character at all, you do not
     have any supplementary characters in `utf8' columns in your 5.1
     database, so you need not worry about converting characters or
     losing data.

In terms of table structure, the catch when converting from the old
`utf8' to the new `utf8' is that the maximum length of a column or
index key is unchanged in terms of bytes. Therefore, it is smaller in
terms of characters, because the maximum length of a character is four
bytes instead of three. The things to watch for when converting your
MySQL 5.1 tables are:

   * Look at the definitions of `utf8' columns, and make sure they will
     not exceed the maximum length for the storage engine.

   * Look at all indexes on `utf8' columns, and make sure they will not
     exceed the maximum length for the storage engine. Sometimes the
     maximum can change due to storage engine enhancements.

Check those things for the *Note `CHAR': char, *Note `VARCHAR': char,
and *Note `TEXT': blob. data types.

If the preceding conditions apply for you, you will have to reduce the
defined length of columns or indexes, or you will have to use `utf8mb3'
rather than `utf8'.

Here are some examples where structural changes may be needed:

   * A *Note `TINYTEXT': blob. column can hold up to 255 bytes, so it
     can hold up to 85 three-byte or 63 four-byte characters. Suppose
     that you have a *Note `TINYTEXT': blob. column that uses `utf8mb3'
     but must be able to contain more than 63 characters. You cannot
     convert it to `utf8' unless you also change the data type to a
     longer type such as *Note `TEXT': blob.

     Similarly, a very long *Note `VARCHAR': char. column may need to be
     changed to one of the longer *Note `TEXT': blob. types if you want
     to convert it from `utf8mb3' to `utf8'.

   * `InnoDB' has a maximum index length of 767 bytes, so for `utf8mb3'
     or `utf8' columns, you can index a maximum of 255 or 191
     characters, respectively. If you currently have `utf8mb3' columns
     with indexes longer than 191 characters, you will need to index a
     smaller number of characters. In an `InnoDB' table, this column
     and index definition is legal:

          col1 VARCHAR(500) CHARACTER SET utf8mb3, INDEX (col1(255))

     To use `utf8' instead, the index must be smaller:

          col1 VARCHAR(500) CHARACTER SET utf8, INDEX (col1(191))

The preceding types of changes are most likely to be required only if
you have very long columns or indexes. Otherwise, you should be able to
convert your tables from `utf8mb3' to `utf8' without problems. You can
do this either by dumping them with *Note `mysqldump': mysqldump. in
MySQL 5.1 and reloading the dump into 6.0, or by using *Note `ALTER
TABLE': alter-table.  after upgrading in place from 5.1 to 6.0.

The following items summarize other potential areas of incompatibility:

   * Performance of four-byte UTF-8 (`utf8') is slower than for
     three-byte UTF-8 (`utf8mb3'). There are tradeoffs: If you want the
     same character set and collation names, you can convert from
     `utf8mb3' to `utf8'. But that will introduce a small performance
     penalty. If you do not want to incur this penalty, continue to use
     `utf8mb3'.

   * `SET NAMES 'utf8'' now causes use of four-byte character set. As
     long as no four-byte character are sent in either direction, there
     should be no problems.  Otherwise, applications that expect to
     receive a maximum of three bytes per character may have problems.
     Conversely, applications that expect to send four-byte characters
     must ensure that the server understands them.

   * Applications cannot send `utf16' or `utf32' character data to a
     pre-6.0 server.

   * Applications that use the old collation IDs to detect `utf8'
     collations need to be updated unless it is okay that these IDs
     signify `utf8mb3' collations in MySQL 6.0.

   * Applications that test for the string `'utf8'' in character set or
     collation names and expect them to refer to the three-byte `utf8'
     may need to be adjusted to recognize `'utf8mb3'' instead.

   * Look at all application programs that process `utf8' data, and
     make sure that buffer lengths are not calculated with an algorithm
     such as `number of characters times 3.'

   * For replication, if four-byte characters are going to be used, all
     servers involved must understand them.

   * Check for other uses of `utf8', such as `_utf8' introducers,
     `utf8' stored routine variables, or `utf8' function return types.

Similar restrictions apply if you attempt to replicate from a MySQL 6.0
master to a MySQL 5.1 slave.  `utf8mb3' data will be seen as `utf8' by
the slave as long as it is represented in binary log events by ID,
rather than by name (as in statements such as *Note `CREATE TABLE':
create-table.). But you cannot send `utf16' or `utf32' data, or data
for the new `utf8'.

If you have upgraded to MySQL 6.0 and then decide to downgrade back to
5.1, these considerations apply:

   * `ucs2' data should present no problems.

   * For an in-place downgrade, `utf8mb3' data will be seen as `utf8'
     in 5.1 and should present no problems.

   * Any definitions that refer to the `utf8mb3', `utf16', or `utf32'
     character set names will not be recognized by 5.1.

   * For objects with definitions that refer to the `utf8' character
     set name, you can dump them with *Note `mysqldump': mysqldump. in
     6.0 and then reload the dump in 5.1, as long as there are no
     four-byte characters in the data. The 5.1 server will see `utf8'
     in the dump file object definitions and create new objects that
     use the 5.1 (three-byte) `utf8' character set.

   * For tables in the `mysql' database, *Note `mysql_upgrade':
     mysql-upgrade. in 6.0 converts `utf8mb3' columns to `utf8'. Thus,
     if you run *Note `mysql_upgrade': mysql-upgrade. after upgrading
     to 6.0, these tables will not be legal in 5.1. You will need to
     convert `utf8' columns to `utf8mb3' with *Note `ALTER TABLE':
     alter-table. before downgrading, or you can do this:

       1. In MySQL 6.0, before downgrading, create a dump file
          containing the `mysql' database tables:

               shell> mysqldump -uroot -p mysql > mysql.sql

       2. Check the dump file to make sure that there are no instances
          of `utf8mb3'. If there are, change them to `utf8'.

       3. Stop the server, downgrade to MySQL 5.1, and start the server
          with the `--skip-grant-tables' option so that it does not try
          to use the `mysql' database tables.

       4. Recreate the dump file to recreate the `mysql' database
          tables:

               shell> mysql mysql < mysql.sql

       5. Restart the server. It should use the `mysql' database tables
          normally.


File: manual.info,  Node: charset-metadata,  Next: charset-conversion,  Prev: charset-unicode-upgrading,  Up: charset

9.1.11 UTF-8 for Metadata
-------------------------

_Metadata_ is `the data about the data.' Anything that _describes_ the
database -- as opposed to being the _contents_ of the database -- is
metadata. Thus column names, database names, user names, version names,
and most of the string results from *Note `SHOW': show. are metadata.
This is also true of the contents of tables in `INFORMATION_SCHEMA',
because those tables by definition contain information about database
objects.

Representation of metadata must satisfy these requirements:

   * All metadata must be in the same character set. Otherwise, neither
     the *Note `SHOW': show. commands nor *Note `SELECT': select.
     statements for tables in `INFORMATION_SCHEMA' would work properly
     because different rows in the same column of the results of these
     operations would be in different character sets.

   * Metadata must include all characters in all languages.  Otherwise,
     users would not be able to name columns and tables using their own
     languages.

To satisfy both requirements, MySQL stores metadata in a Unicode
character set, namely UTF-8. This does not cause any disruption if you
never use accented or non-Latin characters. But if you do, you should
be aware that metadata is in UTF-8.

The metadata requirements mean that the return values of the `USER()',
`CURRENT_USER()', `SESSION_USER()', `SYSTEM_USER()', `DATABASE()', and
`VERSION()' functions have the UTF-8 character set by default.

The server sets the `character_set_system' system variable to the name
of the metadata character set:

     mysql> SHOW VARIABLES LIKE 'character_set_system';
     +----------------------+-------+
     | Variable_name        | Value |
     +----------------------+-------+
     | character_set_system | utf8  |
     +----------------------+-------+

Storage of metadata using Unicode does _not_ mean that the server
returns headers of columns and the results of *Note `DESCRIBE':
describe. functions in the `character_set_system' character set by
default. When you use `SELECT column1 FROM t', the name `column1'
itself is returned from the server to the client in the character set
determined by the value of the `character_set_results' system variable,
which has a default value of `latin1'. If you want the server to pass
metadata results back in a different character set, use the `SET NAMES'
statement to force the server to perform character set conversion. `SET
NAMES' sets the `character_set_results' and other related system
variables. (See *Note charset-connection::.) Alternatively, a client
program can perform the conversion after receiving the result from the
server. It is more efficient for the client perform the conversion, but
this option is not always available for all clients.

If `character_set_results' is set to `NULL', no conversion is performed
and the server returns metadata using its original character set (the
set indicated by `character_set_system').

Error messages returned from the server to the client are converted to
the client character set automatically, as with metadata.

If you are using (for example) the `USER()' function for comparison or
assignment within a single statement, don't worry. MySQL performs some
automatic conversion for you.

     SELECT * FROM t1 WHERE USER() = latin1_column;

This works because the contents of `latin1_column' are automatically
converted to UTF-8 before the comparison.

     INSERT INTO t1 (latin1_column) SELECT USER();

This works because the contents of `USER()' are automatically converted
to `latin1' before the assignment.

Although automatic conversion is not in the SQL standard, the SQL
standard document does say that every character set is (in terms of
supported characters) a `subset' of Unicode. Because it is a well-known
principle that `what applies to a superset can apply to a subset,' we
believe that a collation for Unicode can apply for comparisons with
non-Unicode strings. For more information about coercion of strings,
see *Note charset-collate-tricky::.


File: manual.info,  Node: charset-conversion,  Next: charset-charsets,  Prev: charset-metadata,  Up: charset

9.1.12 Column Character Set Conversion
--------------------------------------

To convert a binary or non-binary string column to use a particular
character set, use *Note `ALTER TABLE': alter-table. For successful
conversion to occur, one of the following conditions must apply:

   * If the column has a binary data type (*Note `BINARY':
     binary-varbinary, *Note `VARBINARY': binary-varbinary, *Note
     `BLOB': blob.), all the values that it contains must be encoded
     using a single character set (the character set you're converting
     the column to). If you use a binary column to store information in
     multiple character sets, MySQL has no way to know which values use
     which character set and cannot convert the data properly.

   * If the column has a non-binary data type (*Note `CHAR': char,
     *Note `VARCHAR': char, *Note `TEXT': blob.), its contents should be
     encoded in the column's character set, not some other character
     set. If the contents are encoded in a different character set, you
     can convert the column to use a binary data type first, and then
     to a non-binary column with the desired character set.

Suppose that a table `t' has a binary column named `col1' defined as
`VARBINARY(50)'. Assuming that the information in the column is encoded
using a single character set, you can convert it to a non-binary column
that has that character set.  For example, if `col1' contains binary
data representing characters in the `greek' character set, you can
convert it as follows:

     ALTER TABLE t MODIFY col1 VARCHAR(50) CHARACTER SET greek;

If your original column has a type of `BINARY(50)', you could convert
it to `CHAR(50)', but the resulting values will be padded with `0x00'
bytes at the end, which may be undesirable. To remove these bytes, use
the `TRIM()' function:

     UPDATE t SET col1 = TRIM(TRAILING 0x00 FROM col1);

Suppose that table `t' has a non-binary column named `col1' defined as
`CHAR(50) CHARACTER SET latin1' but you want to convert it to use
`utf8' so that you can store values from many languages. The following
statement accomplishes this:

     ALTER TABLE t MODIFY col1 CHAR(50) CHARACTER SET utf8;

Conversion may be lossy if the column contains characters that are not
in both character sets.

A special case occurs if you have old tables from MySQL 4.0 or earlier
where a non-binary column contains values that actually are encoded in
a character set different from the server's default character set. For
example, an application might have stored `sjis' values in a column,
even though MySQL's default character set was `latin1'. It is possible
to convert the column to use the proper character set but an additional
step is required. Suppose that the server's default character set was
`latin1' and `col1' is defined as `CHAR(50)' but its contents are
`sjis' values. The first step is to convert the column to a binary data
type, which removes the existing character set information without
performing any character conversion:

     ALTER TABLE t MODIFY col1 BLOB;

The next step is to convert the column to a non-binary data type with
the proper character set:

     ALTER TABLE t MODIFY col1 CHAR(50) CHARACTER SET sjis;

This procedure requires that the table not have been modified already
with statements such as *Note `INSERT': insert. or *Note `UPDATE':
update. after an upgrade to MySQL 4.1 or later. In that case, MySQL
would store new values in the column using `latin1', and the column will
contain a mix of `sjis' and `latin1' values and cannot be converted
properly.

If you specified attributes when creating a column initially, you
should also specify them when altering the table with *Note `ALTER
TABLE': alter-table. For example, if you specified `NOT NULL' and an
explicit `DEFAULT' value, you should also provide them in the *Note
`ALTER TABLE': alter-table. statement.  Otherwise, the resulting column
definition will not include those attributes.


File: manual.info,  Node: charset-charsets,  Prev: charset-conversion,  Up: charset

9.1.13 Character Sets and Collations That MySQL Supports
--------------------------------------------------------

* Menu:

* charset-unicode-sets::         Unicode Character Sets
* charset-we-sets::              West European Character Sets
* charset-ce-sets::              Central European Character Sets
* charset-se-me-sets::           South European and Middle East Character Sets
* charset-baltic-sets::          Baltic Character Sets
* charset-cyrillic-sets::        Cyrillic Character Sets
* charset-asian-sets::           Asian Character Sets

MySQL supports 70+ collations for 30+ character sets. This section
indicates which character sets MySQL supports. There is one subsection
for each group of related character sets. For each character set, the
allowable collations are listed.

You can always list the available character sets and their default
collations with the *Note `SHOW CHARACTER SET': show-character-set.
statement:

     mysql> SHOW CHARACTER SET;
     +----------+-----------------------------+---------------------+--------+
     | Charset  | Description                 | Default collation   | Maxlen |
     +----------+-----------------------------+---------------------+--------+
     | big5     | Big5 Traditional Chinese    | big5_chinese_ci     |      2 |
     | dec8     | DEC West European           | dec8_swedish_ci     |      1 |
     | cp850    | DOS West European           | cp850_general_ci    |      1 |
     | hp8      | HP West European            | hp8_english_ci      |      1 |
     | koi8r    | KOI8-R Relcom Russian       | koi8r_general_ci    |      1 |
     | latin1   | cp1252 West European        | latin1_swedish_ci   |      1 |
     | latin2   | ISO 8859-2 Central European | latin2_general_ci   |      1 |
     | swe7     | 7bit Swedish                | swe7_swedish_ci     |      1 |
     | ascii    | US ASCII                    | ascii_general_ci    |      1 |
     | ujis     | EUC-JP Japanese             | ujis_japanese_ci    |      3 |
     | sjis     | Shift-JIS Japanese          | sjis_japanese_ci    |      2 |
     | hebrew   | ISO 8859-8 Hebrew           | hebrew_general_ci   |      1 |
     | tis620   | TIS620 Thai                 | tis620_thai_ci      |      1 |
     | euckr    | EUC-KR Korean               | euckr_korean_ci     |      2 |
     | koi8u    | KOI8-U Ukrainian            | koi8u_general_ci    |      1 |
     | gb2312   | GB2312 Simplified Chinese   | gb2312_chinese_ci   |      2 |
     | greek    | ISO 8859-7 Greek            | greek_general_ci    |      1 |
     | cp1250   | Windows Central European    | cp1250_general_ci   |      1 |
     | gbk      | GBK Simplified Chinese      | gbk_chinese_ci      |      2 |
     | latin5   | ISO 8859-9 Turkish          | latin5_turkish_ci   |      1 |
     | armscii8 | ARMSCII-8 Armenian          | armscii8_general_ci |      1 |
     | utf8mb3  | UTF-8 Unicode               | utf8mb3_general_ci  |      3 |
     | ucs2     | UCS-2 Unicode               | ucs2_general_ci     |      2 |
     | cp866    | DOS Russian                 | cp866_general_ci    |      1 |
     | keybcs2  | DOS Kamenicky Czech-Slovak  | keybcs2_general_ci  |      1 |
     | macce    | Mac Central European        | macce_general_ci    |      1 |
     | macroman | Mac West European           | macroman_general_ci |      1 |
     | cp852    | DOS Central European        | cp852_general_ci    |      1 |
     | latin7   | ISO 8859-13 Baltic          | latin7_general_ci   |      1 |
     | utf8     | UTF-8 Unicode               | utf8_general_ci     |      4 |
     | cp1251   | Windows Cyrillic            | cp1251_general_ci   |      1 |
     | utf16    | UTF-16 Unicode              | utf16_general_ci    |      4 |
     | cp1256   | Windows Arabic              | cp1256_general_ci   |      1 |
     | cp1257   | Windows Baltic              | cp1257_general_ci   |      1 |
     | utf32    | UTF-32 Unicode              | utf32_general_ci    |      4 |
     | binary   | Binary pseudo charset       | binary              |      1 |
     | geostd8  | GEOSTD8 Georgian            | geostd8_general_ci  |      1 |
     | cp932    | SJIS for Windows Japanese   | cp932_japanese_ci   |      2 |
     | eucjpms  | UJIS for Windows Japanese   | eucjpms_japanese_ci |      3 |
     +----------+-----------------------------+---------------------+--------+

The `utf8' character set prior to MySQL 6.0.4 encoded BMP characters
using up to three bytes per character. In MySQL 6.0.4, this character
set is renamed to `utf8mb3', and a new `utf8' is added that encodes BMP
and supplementary characters using up to four bytes per character. The
`utf16' and `utf32' character sets also were added in MySQL 6.0.4.

In cases where a character set has multiple collations, it might not be
clear which collation is most suitable for a given application. To
avoid choosing the wrong collation, it can be helpful to perform some
comparisons with representative data values to make sure that a given
collation sorts values the way you expect.

Collation-Charts.Org (http://www.collation-charts.org/) is a useful
site for information that shows how one collation compares to another.


File: manual.info,  Node: charset-unicode-sets,  Next: charset-we-sets,  Prev: charset-charsets,  Up: charset-charsets

9.1.13.1 Unicode Character Sets
...............................

MySQL 6.0 has several Unicode character sets:

   * `ucs2', the UCS-2 encoding of the Unicode character set using 16
     bits per character

   * `utf16', the UTF-16 encoding for the Unicode character set; like
     `ucs2' but with an extension for supplementary characters

   * `utf32', the UTF-32 encoding for the Unicode character set using
     32 bits per character

   * `utf8', a UTF-8 encoding of the Unicode character set using one to
     four bytes per character

   * `utf8mb3', a UTF-8 encoding of the Unicode character set using one
     to three bytes per character (known as `utf8' before MySQL 6.0)

You can store text in about 650 languages using these character sets.
This section lists the collations available for each Unicode character
set. For general information about the character sets, see *Note
charset-unicode::.

A similar set of collations is available for each Unicode character
set. These are shown in the following list, where XXX represents the
character set name. For example, `XXX_danish_ci' represents the Danish
collations, the specific names of which are `ucs2_danish_ci',
`utf16_danish_ci', `ucs32_danish_ci', `utf8_danish_ci', and
`utf8mb3_danish_ci'.

   * `XXX_bin'

   * `XXX_czech_ci'

   * `XXX_danish_ci'

   * `XXX_esperanto_ci'

   * `XXX_estonian_ci'

   * `XXX_general_ci' (default)

   * `XXX_hungarian_ci'

   * `XXX_icelandic_ci'

   * `XXX_latvian_ci'

   * `XXX_lithuanian_ci'

   * `XXX_persian_ci'

   * `XXX_polish_ci'

   * `XXX_roman_ci'

   * `XXX_romanian_ci'

   * `XXX_sinhala_ci'

   * `XXX_slovak_ci'

   * `XXX_slovenian_ci'

   * `XXX_spanish2_ci'

   * `XXX_spanish_ci'

   * `XXX_swedish_ci'

   * `XXX_turkish_ci'

   * `XXX_unicode_ci'

The collations for `utf8mb3', `utf16', and `utf32' were added in MySQL
6.0.4. In 6.0.4, the old (three-byte) `utf8' character set was renamed
to `utf8mb3' and the new (four-byte) `utf8' character set was added.
The collation IDs for the `utf8mb3' collations in MySQL 6.0 are the
same as the IDs for the `utf8' collations in MySQL 5.1. In other words,
the IDs are still associated with data for a particular encoding; it is
the encoding name that has changed.

MySQL implements the `XXX_unicode_ci' collations according to the
Unicode Collation Algorithm (UCA) described at
`http://www.unicode.org/reports/tr10/'. The collation uses the
version-4.0.0 UCA weight keys:
`http://www.unicode.org/Public/UCA/4.0.0/allkeys-4.0.0.txt'.
Currently, the `XXX_unicode_ci' collations have only partial support
for the Unicode Collation Algorithm. Some characters are not supported
yet. Also, combining marks are not fully supported. This affects
primarily Vietnamese, Yoruba, and some smaller languages such as
Navajo. The following discussion uses `utf8_unicode_ci' for
concreteness.

For any Unicode character set, operations performed using the
`XXX_general_ci' collation are faster than those for the
`XXX_unicode_ci' collation. For example, comparisons for the
`utf8_general_ci' collation are faster, but slightly less correct, than
comparisons for `utf8_unicode_ci'. The reason for this is that
`utf8_unicode_ci' supports mappings such as expansions; that is, when
one character compares as equal to combinations of other characters.
For example, in German and some other languages ``ss'' is equal to
``ss''.  `utf8_unicode_ci' also supports contractions and ignorable
characters. `utf8_general_ci' is a legacy collation that does not
support expansions, contractions, or ignorable characters. It can make
only one-to-one comparisons between characters.

To further illustrate, the following equalities hold in both
`utf8_general_ci' and `utf8_unicode_ci' (for the effect this has in
comparisons or when doing searches, see *Note
charset-collation-effect::):

     A" = A
     O" = O
     U" = U

A difference between the collations is that this is true for
`utf8_general_ci':

     ss = s

Whereas this is true for `utf8_unicode_ci':

     ss = ss

MySQL implements language-specific collations for the `utf8' character
set only if the ordering with `utf8_unicode_ci' does not work well for
a language. For example, `utf8_unicode_ci' works fine for German and
French, so there is no need to create special `utf8' collations for
these two languages.

`utf8_general_ci' also is satisfactory for both German and French,
except that ``ss'' is equal to ``s'', and not to ``ss''. If this is
acceptable for your application, then you should use `utf8_general_ci'
because it is faster.  Otherwise, use `utf8_unicode_ci' because it is
more accurate.

`utf8_swedish_ci', like other `utf8' language-specific collations, is
derived from `utf8_unicode_ci' with additional language rules. For
example, in Swedish, the following relationship holds, which is not
something expected by a German or French speaker:

     U" = Y < O"

The `XXX_spanish_ci' and `XXX_spanish2_ci' collations correspond to
modern Spanish and traditional Spanish, respectively. In both
collations, ``ñ'' (n-tilde) is a separate letter between ``n'' and
``o''. In addition, for traditional Spanish, ``ch'' is a separate
letter between ``c'' and ``d'', and ``ll'' is a separate letter between
``l'' and ``m''

In the `XXX_roman_ci' collations, `I' and `J' compare as equal, and `U'
and `V' compare as equal.

For all Unicode collations except the `binary' (`_bin') collations,
MySQL performs a table lookup to find a character's collating weight.
This weight can be displayed using the `WEIGHT_STRING()' function. (See
*Note string-functions::.) But if a character is not in the table (for
example, because it is a `new' character), collating weight
determination becomes more complex:

   * For BMP characters in general collations (for example,
     `utf8_general_ci'), weight = code point.

   * For BMP characters in UCA collations (for example,
     `utf8_unicode_ci'), the following algorithm applies:

          if (code >= 0x3400 && code <= 0x4DB5)
            base= 0xFB80; /* CJK Ideograph Extension */
          else if (code >= 0x4E00 && code <= 0x9FA5)
            base= 0xFB40; /* CJK Ideograph */
          else
            base= 0xFBC0; /* All other characters */
          aaaa= base +  (code >> 15);
          bbbb= (code & 0x7FFF) | 0x8000;

     The result is a sequence of two collating elements, `aaaa'
     followed by `bbbb'. For example:

          mysql> SELECT HEX(WEIGHT_STRING(_ucs2 0x04CF COLLATE ucs2_unicode_ci));
          +----------------------------------------------------------+
          | HEX(WEIGHT_STRING(_ucs2 0x04CF COLLATE ucs2_unicode_ci)) |
          +----------------------------------------------------------+
          | FBC084CF                                                 |
          +----------------------------------------------------------+

     Thus, `U+04cf CYRILLIC SMALL LETTER PALOCHKA' currently is, with
     all UCA collations, greater than `U+04c0 CYRILLIC LETTER
     PALOCHKA'. Eventually, after further collation tuning, all
     palochkas will sort together.

   * For supplementary characters in general collations, the weight is
     the weight for `0xfffd REPLACEMENT CHARACTER'. For supplementary
     characters in UCA collations, their collating weight is `0xfffd'.
     That is, to MySQL, all supplementary characters are equal to each
     other, and greater than almost all BMP characters.

     An example with Deseret characters and `COUNT(DISTINCT)':

          CREATE TABLE t (s1 VARCHAR(5) CHARACTER SET utf32 COLLATE utf32_unicode_ci);
          INSERT INTO t VALUES (0xfffd);   /* REPLACEMENT CHARACTER */
          INSERT INTO t VALUES (0x010412); /* DESERET CAPITAL LETTER BEE */
          INSERT INTO t VALUES (0x010413); /* DESERET CAPITAL LETTER TEE */
          SELECT COUNT(DISTINCT s1) FROM t;

     The result is 1, because Deseret Bee = Deseret Tee = Replacement
     Character, in the MySQL Unicode collation.

     An example with cuneiform characters and `WEIGHT_STRING()':

          /*
          The four characters in the INSERT string are
          00000041  # LATIN CAPITAL LETTER A
          0001218F # CUNEIFORM SIGN KAB
          000121A7 # CUNEIFORM SIGN KISH
          00000042  # LATIN CAPITAL LETTER B
          */
          CREATE TABLE t (s1 CHAR(4) CHARACTER SET utf32 COLLATE utf32_unicode_ci);
          INSERT INTO t VALUES (0x000000410001218f000121a700000042);
          SELECT HEX(WEIGHT_STRING(s1)) FROM t;

     The result is:

          0E33 FFFD FFFD 0E4A

     `0E33' and `0E4A' are primary weights as in UCA 4.0.0
     (ftp://www.unicode.org/Public/UCA/4.0.0/allkeys-4.0.0.txt). `FFFD'
     is the weight for KAB and also for KISH.

The current rule that all supplementary characters are equal to each
other is non-optimal. However, we don't expect the rule to cause
trouble. These characters are very rare, so it will be very rare that a
multi-character string consists entirely of supplementary characters.
In Japan, since the supplementary characters are obscure Kanji
ideographs, the typical user doesn't care what order they're in,
anyway. If you really want to get rows sorted by MySQL's rule and
secondarily by code point value, it is easy:

     ORDER BY s1 COLLATE utf32_unicode_ci, s1 COLLATE utf32_bin

*The utf16_bin Collation*

There is a difference between `ordering by the character's code value'
and `ordering by the character's binary representation,' a difference
that appears only with `utf16_bin', because of surrogates.

Suppose that `utf16_bin' (the binary collation for `utf16') was a binary
comparison `byte by byte' rather than `character by character.' If that
were so, then the order of characters in `utf16_bin' would differ from
the order in `utf8_bin'. For example, here is a chart showing two rare
characters. The first character is in the range `E000'-`FFFF', so it is
greater than a surrogate but less than a supplementary. The second
character is a supplementary.

     Code point  Character                    utf8         utf16
     ----------  ---------                    ----         -----
     0FF9D       HALFWIDTH KATAKANA LETTER N  EF BE 9D     FF 9D
     10384       UGARITIC LETTER DELTA        F0 90 8E 84  D8 00 DF 84

The two characters in the chart are in order by code point value,
because `0xff9d' < `0x10384'. And they are in order by `utf8' value,
because `0xef < 0xf0'. But they are not in order by `utf16' value, if
we use byte-by-byte comparison, because `0xff > 0xd8'.

So MySQL's `utf16_bin' collation is not `byte by byte.' It is `by code
point.' When MySQL sees a supplementary-character encoding in utf16, it
converts to the character's code-point value, and then compares.
Therefore `utf8_bin' and `utf16_bin' are the same ordering. This is
consistent with the SQL:2008 standard requirement for a UCS_BASIC
collation: `UCS_BASIC is a collation in which the ordering is
determined entirely by the Unicode scalar values of the characters in
the strings being sorted. It is applicable to the UCS character
repertoire. Since every character repertoire is a subset of the UCS
repertoire, the UCS_BASIC collation is potentially applicable to every
character set. NOTE 11 --- The Unicode scalar value of a character is
its code point treated as an unsigned integer.'

If the character set is `ucs2', then comparison is byte-by-byte, but
`ucs2' strings shouldn't contain surrogates, anyway.

For additional information about Unicode collations in MySQL, see
Collation-Charts.Org (utf8
(http://www.collation-charts.org/mysql60/by-charset.html#utf8)).


File: manual.info,  Node: charset-we-sets,  Next: charset-ce-sets,  Prev: charset-unicode-sets,  Up: charset-charsets

9.1.13.2 West European Character Sets
.....................................

Western European character sets cover most West European languages,
such as French, Spanish, Catalan, Basque, Portuguese, Italian,
Albanian, Dutch, German, Danish, Swedish, Norwegian, Finnish, Faroese,
Icelandic, Irish, Scottish, and English.

   * `ascii' (US ASCII) collations:

        * `ascii_bin'

        * `ascii_general_ci' (default)

   * `cp850' (DOS West European) collations:

        * `cp850_bin'

        * `cp850_general_ci' (default)

   * `dec8' (DEC Western European) collations:

        * `dec8_bin'

        * `dec8_swedish_ci' (default)

   * `hp8' (HP Western European) collations:

        * `hp8_bin'

        * `hp8_english_ci' (default)

   * `latin1' (cp1252 West European) collations:

        * `latin1_bin'

        * `latin1_danish_ci'

        * `latin1_general_ci'

        * `latin1_general_cs'

        * `latin1_german1_ci'

        * `latin1_german2_ci'

        * `latin1_spanish_ci'

        * `latin1_swedish_ci' (default)

     `latin1' is the default character set.  MySQL's `latin1' is the
     same as the Windows `cp1252' character set. This means it is the
     same as the official `ISO 8859-1' or IANA (Internet Assigned
     Numbers Authority) `latin1', except that IANA `latin1' treats the
     code points between `0x80' and `0x9f' as `undefined,' whereas
     `cp1252', and therefore MySQL's `latin1', assign characters for
     those positions. For example, `0x80' is the Euro sign. For the
     `undefined' entries in `cp1252', MySQL translates `0x81' to Unicode
     `0x0081', `0x8d' to `0x008d', `0x8f' to `0x008f', `0x90' to
     `0x0090', and `0x9d' to `0x009d'.

     The `latin1_swedish_ci' collation is the default that probably is
     used by the majority of MySQL customers. Although it is frequently
     said that it is based on the Swedish/Finnish collation rules,
     there are Swedes and Finns who disagree with this statement.

     The `latin1_german1_ci' and `latin1_german2_ci' collations are
     based on the DIN-1 and DIN-2 standards, where DIN stands for
     _Deutsches Institut fu"r Normung_ (the German equivalent of ANSI).
     DIN-1 is called the `dictionary collation' and DIN-2 is called the
     `phone book collation.' For an example of the effect this has in
     comparisons or when doing searches, see *Note
     charset-collation-effect::.

        * `latin1_german1_ci' (dictionary) rules:

               A" = A
               O" = O
               U" = U
               ss = s

        * `latin1_german2_ci' (phone-book) rules:

               A" = AE
               O" = OE
               U" = UE
               ss = ss

     For an example of the effect this has in comparisons or when doing
     searches, see *Note charset-collation-effect::.

     In the `latin1_spanish_ci' collation, ``ñ'' (n-tilde) is a
     separate letter between ``n'' and ``o''.

   * `macroman' (Mac West European) collations:

        * `macroman_bin'

        * `macroman_general_ci' (default)

   * `swe7' (7bit Swedish) collations:

        * `swe7_bin'

        * `swe7_swedish_ci' (default)

For additional information about Western European collations in MySQL,
see Collation-Charts.Org (ascii
(http://www.collation-charts.org/mysql60/by-charset.html#ascii), cp850
(http://www.collation-charts.org/mysql60/by-charset.html#cp850), dec8
(http://www.collation-charts.org/mysql60/by-charset.html#dec8), hp8
(http://www.collation-charts.org/mysql60/by-charset.html#hp8), latin1
(http://www.collation-charts.org/mysql60/by-charset.html#latin1),
macroman
(http://www.collation-charts.org/mysql60/by-charset.html#macroman),
swe7 (http://www.collation-charts.org/mysql60/by-charset.html#swe7)).


File: manual.info,  Node: charset-ce-sets,  Next: charset-se-me-sets,  Prev: charset-we-sets,  Up: charset-charsets

9.1.13.3 Central European Character Sets
........................................

MySQL provides some support for character sets used in the Czech
Republic, Slovakia, Hungary, Romania, Slovenia, Croatia, Poland, and
Serbia (Latin).

   * `cp1250' (Windows Central European) collations:

        * `cp1250_bin'

        * `cp1250_croatian_ci'

        * `cp1250_czech_cs'

        * `cp1250_general_ci' (default)

        * `cp1250_polish_ci'

   * `cp852' (DOS Central European) collations:

        * `cp852_bin'

        * `cp852_general_ci' (default)

   * `keybcs2' (DOS Kamenicky Czech-Slovak) collations:

        * `keybcs2_bin'

        * `keybcs2_general_ci' (default)

   * `latin2' (ISO 8859-2 Central European) collations:

        * `latin2_bin'

        * `latin2_croatian_ci'

        * `latin2_czech_cs'

        * `latin2_general_ci' (default)

        * `latin2_hungarian_ci'

   * `macce' (Mac Central European) collations:

        * `macce_bin'

        * `macce_general_ci' (default)

For additional information about Central European collations in MySQL,
see Collation-Charts.Org (cp1250
(http://www.collation-charts.org/mysql60/by-charset.html#cp1250), cp852
(http://www.collation-charts.org/mysql60/by-charset.html#cp852),
keybcs2
(http://www.collation-charts.org/mysql60/by-charset.html#keybcs2),
latin2 (http://www.collation-charts.org/mysql60/by-charset.html#latin2),
macce (http://www.collation-charts.org/mysql60/by-charset.html#macce)).


File: manual.info,  Node: charset-se-me-sets,  Next: charset-baltic-sets,  Prev: charset-ce-sets,  Up: charset-charsets

9.1.13.4 South European and Middle East Character Sets
......................................................

South European and Middle Eastern character sets supported by MySQL
include Armenian, Arabic, Georgian, Greek, Hebrew, and Turkish.

   * `armscii8' (ARMSCII-8 Armenian) collations:

        * `armscii8_bin'

        * `armscii8_general_ci' (default)

   * `cp1256' (Windows Arabic) collations:

        * `cp1256_bin'

        * `cp1256_general_ci' (default)

   * `geostd8' (GEOSTD8 Georgian) collations:

        * `geostd8_bin'

        * `geostd8_general_ci' (default)

   * `greek' (ISO 8859-7 Greek) collations:

        * `greek_bin'

        * `greek_general_ci' (default)

   * `hebrew' (ISO 8859-8 Hebrew) collations:

        * `hebrew_bin'

        * `hebrew_general_ci' (default)

   * `latin5' (ISO 8859-9 Turkish) collations:

        * `latin5_bin'

        * `latin5_turkish_ci' (default)

For additional information about South European and Middle Eastern
collations in MySQL, see Collation-Charts.Org (armscii8
(http://www.collation-charts.org/mysql60/by-charset.html#armscii8),
cp1256 (http://www.collation-charts.org/mysql60/by-charset.html#cp1256),
geostd8
(http://www.collation-charts.org/mysql60/by-charset.html#geostd8),
greek (http://www.collation-charts.org/mysql60/by-charset.html#greek),
hebrew (http://www.collation-charts.org/mysql60/by-charset.html#hebrew),
latin5
(http://www.collation-charts.org/mysql60/by-charset.html#latin5)).


File: manual.info,  Node: charset-baltic-sets,  Next: charset-cyrillic-sets,  Prev: charset-se-me-sets,  Up: charset-charsets

9.1.13.5 Baltic Character Sets
..............................

The Baltic character sets cover Estonian, Latvian, and Lithuanian
languages.

   * `cp1257' (Windows Baltic) collations:

        * `cp1257_bin'

        * `cp1257_general_ci' (default)

        * `cp1257_lithuanian_ci'

   * `latin7' (ISO 8859-13 Baltic) collations:

        * `latin7_bin'

        * `latin7_estonian_cs'

        * `latin7_general_ci' (default)

        * `latin7_general_cs'

For additional information about Baltic collations in MySQL, see
Collation-Charts.Org (cp1257
(http://www.collation-charts.org/mysql60/by-charset.html#cp1257),
latin7
(http://www.collation-charts.org/mysql60/by-charset.html#latin7)).


File: manual.info,  Node: charset-cyrillic-sets,  Next: charset-asian-sets,  Prev: charset-baltic-sets,  Up: charset-charsets

9.1.13.6 Cyrillic Character Sets
................................

The Cyrillic character sets and collations are for use with Belarusian,
Bulgarian, Russian, Ukrainian, and Serbian (Cyrillic) languages.

   * `cp1251' (Windows Cyrillic) collations:

        * `cp1251_bin'

        * `cp1251_bulgarian_ci'

        * `cp1251_general_ci' (default)

        * `cp1251_general_cs'

        * `cp1251_ukrainian_ci'

   * `cp866' (DOS Russian) collations:

        * `cp866_bin'

        * `cp866_general_ci' (default)

   * `koi8r' (KOI8-R Relcom Russian) collations:

        * `koi8r_bin'

        * `koi8r_general_ci' (default)

   * `koi8u' (KOI8-U Ukrainian) collations:

        * `koi8u_bin'

        * `koi8u_general_ci' (default)

For additional information about Cyrillic collations in MySQL, see
Collation-Charts.Org (cp1251
(http://www.collation-charts.org/mysql60/by-charset.html#cp1251), cp866
(http://www.collation-charts.org/mysql60/by-charset.html#cp866), koi8r
(http://www.collation-charts.org/mysql60/by-charset.html#koi8r), koi8u
(http://www.collation-charts.org/mysql60/by-charset.html#koi8u)).  ).


File: manual.info,  Node: charset-asian-sets,  Prev: charset-cyrillic-sets,  Up: charset-charsets

9.1.13.7 Asian Character Sets
.............................

* Menu:

* charset-cp932::                The `cp932' Character Set

The Asian character sets that we support include Chinese, Japanese,
Korean, and Thai. These can be complicated. For example, the Chinese
sets must allow for thousands of different characters. See *Note
charset-cp932::, for additional information about the `cp932' and
`sjis' character sets.

For answers to some common questions and problems relating support for
Asian character sets in MySQL, see *Note faqs-cjk::.

   * `big5' (Big5 Traditional Chinese) collations:

        * `big5_bin'

        * `big5_chinese_ci' (default)

   * `cp932' (SJIS for Windows Japanese) collations:

        * `cp932_bin'

        * `cp932_japanese_ci' (default)

   * `eucjpms' (UJIS for Windows Japanese) collations:

        * `eucjpms_bin'

        * `eucjpms_japanese_ci' (default)

   * `euckr' (EUC-KR Korean) collations:

        * `euckr_bin'

        * `euckr_korean_ci' (default)

   * `gb2312' (GB2312 Simplified Chinese) collations:

        * `gb2312_bin'

        * `gb2312_chinese_ci' (default)

   * `gbk' (GBK Simplified Chinese) collations:

        * `gbk_bin'

        * `gbk_chinese_ci' (default)

   * `sjis' (Shift-JIS Japanese) collations:

        * `sjis_bin'

        * `sjis_japanese_ci' (default)

   * `tis620' (TIS620 Thai) collations:

        * `tis620_bin'

        * `tis620_thai_ci' (default)

   * `ujis' (EUC-JP Japanese) collations:

        * `ujis_bin'

        * `ujis_japanese_ci' (default)

The `big5_chinese_ci' collation sorts on number of strokes.

For additional information about Asian collations in MySQL, see
Collation-Charts.Org (big5
(http://www.collation-charts.org/mysql60/by-charset.html#big5), cp932
(http://www.collation-charts.org/mysql60/by-charset.html#cp932),
eucjpms
(http://www.collation-charts.org/mysql60/by-charset.html#eucjpms),
euckr (http://www.collation-charts.org/mysql60/by-charset.html#euckr),
gb2312 (http://www.collation-charts.org/mysql60/by-charset.html#gb2312),
gbk (http://www.collation-charts.org/mysql60/by-charset.html#gbk), sjis
(http://www.collation-charts.org/mysql60/by-charset.html#sjis), tis620
(http://www.collation-charts.org/mysql60/by-charset.html#tis620), ujis
(http://www.collation-charts.org/mysql60/by-charset.html#ujis)).


File: manual.info,  Node: charset-cp932,  Prev: charset-asian-sets,  Up: charset-asian-sets

9.1.13.8 The `cp932' Character Set
..................................

*Why is `cp932' needed?*

In MySQL, the `sjis' character set corresponds to the `Shift_JIS'
character set defined by IANA, which supports JIS X0201 and JIS X0208
characters. (See `http://www.iana.org/assignments/character-sets'.)

However, the meaning of `SHIFT JIS' as a descriptive term has become
very vague and it often includes the extensions to `Shift_JIS' that are
defined by various vendors.

For example, `SHIFT JIS' used in Japanese Windows environments is a
Microsoft extension of `Shift_JIS' and its exact name is `Microsoft
Windows Codepage : 932' or `cp932'. In addition to the characters
supported by `Shift_JIS', `cp932' supports extension characters such as
NEC special characters, NEC selected -- IBM extended characters, and
IBM extended characters.

Many Japanese users have experienced problems using these extension
characters. These problems stem from the following factors:

   * MySQL automatically converts character sets.

   * Character sets are converted via Unicode (`ucs2').

   * The `sjis' character set does not support the conversion of these
     extension characters.

   * There are several conversion rules from so-called `SHIFT JIS' to
     Unicode, and some characters are converted to Unicode differently
     depending on the conversion rule. MySQL supports only one of these
     rules (described later).

The MySQL `cp932' character set is designed to solve these problems.

Because MySQL supports character set conversion, it is important to
separate IANA `Shift_JIS' and `cp932' into two different character sets
because they provide different conversion rules.

*How does `cp932' differ from `sjis'?*

The `cp932' character set differs from `sjis' in the following ways:

   * `cp932' supports NEC special characters, NEC selected -- IBM
     extended characters, and IBM selected characters.

   * Some `cp932' characters have two different code points, both of
     which convert to the same Unicode code point. When converting from
     Unicode back to `cp932', one of the code points must be selected.
     For this `round trip conversion,' the rule recommended by
     Microsoft is used. (See
     `http://support.microsoft.com/kb/170559/EN-US/'.)

     The conversion rule works like this:

        * If the character is in both JIS X 0208 and NEC special
          characters, use the code point of JIS X 0208.

        * If the character is in both NEC special characters and IBM
          selected characters, use the code point of NEC special
          characters.

        * If the character is in both IBM selected characters and NEC
          selected -- IBM extended characters, use the code point of
          IBM extended characters.

     The table shown at
     `http://www.microsoft.com/globaldev/reference/dbcs/932.htm'
     provides information about the Unicode values of `cp932'
     characters. For `cp932' table entries with characters under which
     a four-digit number appears, the number represents the
     corresponding Unicode (`ucs2') encoding. For table entries with an
     underlined two-digit value appears, there is a range of `cp932'
     character values that begin with those two digits. Clicking such a
     table entry takes you to a page that displays the Unicode value for
     each of the `cp932' characters that begin with those digits.

     The following links are of special interest. They correspond to
     the encodings for the following sets of characters:

        * NEC special characters:

               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_87.htm'

        * NEC selected -- IBM extended characters:

               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_ED.htm'
               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_EE.htm'

        * IBM selected characters:

               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_FA.htm'
               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_FB.htm'
               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_FC.htm'

   * `cp932' supports conversion of user-defined characters in
     combination with `eucjpms', and solves the problems with
     `sjis'/`ujis' conversion. For details, please refer to
     `http://www.opengroup.or.jp/jvc/cde/sjis-euc-e.html'.

For some characters, conversion to and from `ucs2' is different for
`sjis' and `cp932'. The following tables illustrate these differences.

Conversion to `ucs2':

*`sjis'/`cp932' Value*   *`sjis' -> `ucs2'        *`cp932' -> `ucs2'
                         Conversion*              Conversion*
5C                       005C                     005C
7E                       007E                     007E
815C                     2015                     2015
815F                     005C                     FF3C
8160                     301C                     FF5E
8161                     2016                     2225
817C                     2212                     FF0D
8191                     00A2                     FFE0
8192                     00A3                     FFE1
81CA                     00AC                     FFE2

Conversion from `ucs2':

*`ucs2' value*           *`ucs2' -> `sjis'        *`ucs2' -> `cp932'
                         Conversion*              Conversion*
005C                     815F                     5C
007E                     7E                       7E
00A2                     8191                     3F
00A3                     8192                     3F
00AC                     81CA                     3F
2015                     815C                     815C
2016                     8161                     3F
2212                     817C                     3F
2225                     3F                       8161
301C                     8160                     3F
FF0D                     3F                       817C
FF3C                     3F                       815F
FF5E                     3F                       8160
FFE0                     3F                       8191
FFE1                     3F                       8192
FFE2                     3F                       81CA

Users of any Japanese character sets should be aware that using
`--character-set-client-handshake' (or
`--skip-character-set-client-handshake') has an important effect. See
*Note server-options::.


File: manual.info,  Node: charset-configuration,  Next: error-message-language,  Prev: charset,  Up: internationalization-localization

9.2 The Character Set Used for Data and Sorting
===============================================

* Menu:

* german-character-set::         Using the German Character Set

By default, MySQL uses the `latin1' (cp1252 West European) character
set and the `latin1_swedish_ci' collation that sorts according to
Swedish/Finnish rules. These defaults are suitable for the United
States and most of Western Europe.

All MySQL binary distributions are compiled with
`--with-extra-charsets=complex'.  This adds code to all standard
programs that enables them to handle `latin1' and all multi-byte
character sets within the binary. Other character sets are loaded from a
character-set definition file when needed.

The character set determines what characters are allowed in
identifiers. The collation determines how strings are sorted by the
`ORDER BY' and `GROUP BY' clauses of the *Note `SELECT': select.
statement.

You can change the default server character set and collation with the
`--character-set-server' and `--collation-server' options when you
start the server. The collation must be a legal collation for the
default character set. (Use the *Note `SHOW COLLATION': show-collation.
statement to determine which collations are available for each
character set.) See *Note server-options::.

The character sets available depend on the `--with-charset=CHARSET_NAME'
and `--with-extra-charsets=LIST-OF-CHARSETS | complex | all | none'
options to `configure', and the character set configuration files
listed in `SHAREDIR/charsets/Index'.  See *Note configure-options::.

If you change the character set when running MySQL, that may also
change the sort order. Consequently, you must run *Note `myisamchk -r
-q --set-collation=COLLATION_NAME': myisamchk.  on all `MyISAM' tables,
or your indexes may not be ordered correctly.

When a client connects to a MySQL server, the server indicates to the
client what the server's default character set is. The client switches
to this character set for this connection.

You should use *Note `mysql_real_escape_string()':
mysql-real-escape-string. when escaping strings for an SQL query.
*Note `mysql_real_escape_string()': mysql-real-escape-string. is
identical to the old *Note `mysql_escape_string()':
mysql-escape-string. function, except that it takes the `MYSQL'
connection handle as the first parameter so that the appropriate
character set can be taken into account when escaping characters.

If the client is compiled with paths that differ from where the server
is installed and the user who configured MySQL didn't include all
character sets in the MySQL binary, you must tell the client where it
can find the additional character sets it needs if the server runs with
a different character set from the client.  You can do this by
specifying a `--character-sets-dir' option to indicate the path to the
directory in which the dynamic MySQL character sets are stored. For
example, you can put the following in an option file:

     [client]
     character-sets-dir=/usr/local/mysql/share/mysql/charsets

You can force the client to use specific character set as follows:

     [client]
     default-character-set=CHARSET_NAME

This is normally unnecessary, however.


File: manual.info,  Node: german-character-set,  Prev: charset-configuration,  Up: charset-configuration

9.2.1 Using the German Character Set
------------------------------------

In MySQL 6.0, character set and collation are specified separately.
This means that if you want German sort order, you should select the
`latin1' character set and either the `latin1_german1_ci' or
`latin1_german2_ci' collation. For example, to start the server with
the `latin1_german1_ci' collation, use the
`--character-set-server=latin1' and
`--collation-server=latin1_german1_ci' options.

For information on the differences between these two collations, see
*Note charset-we-sets::.


File: manual.info,  Node: error-message-language,  Next: adding-character-set,  Prev: charset-configuration,  Up: internationalization-localization

9.3 Setting the Error Message Language
======================================

By default, *Note `mysqld': mysqld. produces error messages in English,
but they can also be displayed in any of these other languages: Czech,
Danish, Dutch, Estonian, French, German, Greek, Hungarian, Italian,
Japanese, Korean, Norwegian, Norwegian-ny, Polish, Portuguese,
Romanian, Russian, Slovak, Spanish, or Swedish.

To start *Note `mysqld': mysqld. with a particular language for error
messages, use the `--language' or `-L' option. The option value can be
a language name or the full path to the error message file. For example:

     shell> mysqld --language=swedish

Or:

     shell> mysqld --language=/usr/local/share/swedish

The language name should be specified in lowercase.

By default, the language files are located in the `share/LANGUAGE'
directory under the MySQL base directory.

You can also change the content of the error messages produced by the
server. Details can be found in the MySQL Internals manual, available at
`http://forge.mysql.com/wiki/MySQL_Internals_Error_Messages'.  If you
upgrade to a newer version of MySQL after changing the error messages,
remember to repeat your changes after the upgrade.


File: manual.info,  Node: adding-character-set,  Next: adding-collation,  Prev: error-message-language,  Up: internationalization-localization

9.4 Adding a New Character Set
==============================

* Menu:

* character-arrays::             The Character Definition Arrays
* string-collating::             String Collating Support
* multi-byte-characters::        Multi-Byte Character Support

This section discusses the procedure for adding a new character set to
MySQL. You must have a MySQL source distribution to use these
instructions. The proper procedure depends on whether the character set
is simple or complex:

   * If the character set does not need to use special string collating
     routines for sorting and does not need multi-byte character
     support, it is simple.

   * If the character set needs either of those features, it is complex.

For example, `greek' and `swe7' are simple character sets, whereas
`big5' and `czech' are complex character sets.

In the following instructions, MYSET represents the name of the
character set that you want to add.

  1. Add a `<charset>' element for MYSET to the
     `sql/share/charsets/Index.xml' file. Use the existing contents in
     the file as a guide to adding new contents.

     The `<charset>' element must list all the collations for the
     character set. These must include at least a binary collation and
     a default collation. The default collation is usually named using
     a suffix of `general_ci' (general, case insensitive). It is
     possible for the binary collation to be the default collation, but
     usually they are different. The default collation should have a
     `primary' flag. The binary collation should have a `binary' flag.

     You must assign a unique ID number to each collation. As of MySQL
     6.0.8, the range of IDs from 1024 to 2047 is reserved for
     user-defined collations. Before 6.0.8, the ID must be chosen from
     the range 1 to 254. To find the maximum of the currently used
     collation IDs, use this query:

          SELECT MAX(ID) FROM INFORMATION_SCHEMA.COLLATIONS;

  2. This step depends on whether you are adding a simple or complex
     character set. A simple character set requires only a
     configuration file, whereas a complex character set requires C
     source file that defines collation functions, multi-byte
     functions, or both.

     For a simple character set, create a configuration file,
     `MYSET.xml', that describes the character set properties. Create
     this file in the `sql/share/charsets' directory. (You can use a
     copy of `latin1.xml' as the basis for this file.) The syntax for
     the file is very simple:

        * Comments are written as ordinary XML comments (`<!-- TEXT
          -->').

        * Words within `<map>' array elements are separated by
          arbitrary amounts of whitespace.

        * Each word within `<map>' array elements must be a number in
          hexadecimal format.

        * The `<map>' array element for the `<ctype>' element has 257
          words.  The other `<map>' array elements after that have 256
          words. See *Note character-arrays::.

        * For each collation listed in the `<charset>' element for the
          character set in `Index.xml', `MYSET.xml' must contain a
          `<collation>' element that defines the character ordering.

     For a complex character set, create a C source file that describes
     the character set properties and defines the support routines
     necessary to properly perform operations on the character set:

       1. Create the file `ctype-MYSET.c' in the `strings' directory.
          Look at one of the existing `ctype-*.c' files (such as
          `ctype-big5.c') to see what needs to be defined. The arrays
          in your file must have names like `ctype_MYSET',
          `to_lower_MYSET', and so on. These correspond to the arrays
          for a simple character set. See *Note character-arrays::.

       2. For each collation listed in the `<charset>' element for the
          character set in `Index.xml', the `ctype-MYSET.c' file must
          provide an implementation of the collation.

       3. If you need string collating functions, see *Note
          string-collating::.

       4. If you need multi-byte character support, see *Note
          multi-byte-characters::.

  3. Follow these steps to modify the configuration information.  Use
     the existing configuration information as a guide to adding
     information for MYSYS. The example here assumes that the character
     set has default and binary collations, but more lines will be
     needed if MYSET has additional collations.

       1. Edit `mysys/charset-def.c', and `register' the collations for
          the new character set.

          Add these lines to the `declaration' section:

               #ifdef HAVE_CHARSET_MYSET
               extern CHARSET_INFO my_charset_MYSET_general_ci;
               extern CHARSET_INFO my_charset_MYSET_bin;
               #endif

          Add these lines to the `registration' section:

               #ifdef HAVE_CHARSET_MYSET
                 add_compiled_collation(&my_charset_MYSET_general_ci);
                 add_compiled_collation(&my_charset_MYSET_bin);
               #endif

       2. If the character set uses `ctype-MYSET.c', edit
          `strings/Makefile.am' and add `ctype-MYSET.c' to each
          definition of the `CSRCS' variable, and to the `EXTRA_DIST'
          variable.

       3. If the character set uses `ctype-MYSET.c', edit
          `libmysql/Makefile.shared' and add `ctype-MYSET.lo' to the
          `mystringsobjects' definition.

       4. Edit `config/ac-macros/character_sets.m4':

            1. Add MYSET to one of the `define(CHARSETS_AVAILABLE...)'
               lines in alphabetic order.

            2. Add MYSET to `CHARSETS_COMPLEX'. This is needed even for
               simple character sets, or `configure' will not recognize
               `--with-charset=MYSET'.

            3. Add MYSET to the first `case' control structure. Omit the
               `USE_MB' and `USE_MB_IDENT' lines for 8-bit character
               sets.

                    MYSET)
                      AC_DEFINE(HAVE_CHARSET_MYSET, 1, [Define to enable charset MYSET])
                      AC_DEFINE([USE_MB], 1, [Use multi-byte character routines])
                      AC_DEFINE(USE_MB_IDENT, 1)
                      ;;

            4. Add MYSET to the second `case' control structure:

                    MYSET)
                      default_charset_default_collation="MYSET_general_ci"
                      default_charset_collations="MYSET_general_ci MYSET_bin"
                      ;;

  4. Reconfigure, recompile, and test.


File: manual.info,  Node: character-arrays,  Next: string-collating,  Prev: adding-character-set,  Up: adding-character-set

9.4.1 The Character Definition Arrays
-------------------------------------

Each simple character set has a configuration file located in the
`sql/share/charsets' directory. The file is named `MYSET.xml'. It uses
`<map>' array elements to list character set properties. `<map>'
elements appear within these elements:

   * `<ctype>' defines attributes for each character

   * `<lower>' and `<upper>' list the lowercase and uppercase characters

   * `<unicode>' maps 8-bit character values to Unicode values

   * `<collation>' elements indicate character ordering for comparisons
     and sorts, one element per collation (binary collations need no
     `<map>' element because the character codes themselves provide the
     ordering)

For a complex character set as implemented in a `ctype-MYSET.c' file in
the `strings' directory, there are corresponding arrays:
`ctype_MYSET[]', `to_lower_MYSET[]', and so forth. Not every complex
character set has all of the arrays. See the existing `ctype-*.c' files
for examples. See the `CHARSET_INFO.txt' file in the `strings'
directory for additional information.

The `ctype' array is indexed by character value + 1 and has 257
elements. This is an old legacy convention for handling `EOF'. The
other arrays are indexed by character value and have 256 elements.

`ctype' array elements are bit values. Each element describes the
attributes of a single character in the character set. Each attribute
is associated with a bitmask, as defined in `include/m_ctype.h':

     #define _MY_U   01      /* Upper case */
     #define _MY_L   02      /* Lower case */
     #define _MY_NMR 04      /* Numeral (digit) */
     #define _MY_SPC 010     /* Spacing character */
     #define _MY_PNT 020     /* Punctuation */
     #define _MY_CTR 040     /* Control character */
     #define _MY_B   0100    /* Blank */
     #define _MY_X   0200    /* heXadecimal digit */

The `ctype' value for a given character should be the union of the
applicable bitmask values that describe the character. For example,
`'A'' is an uppercase character (`_MY_U') as well as a hexadecimal
digit (`_MY_X'), so its `ctype' value should be defined like this:

     ctype['A'+1] = _MY_U | _MY_X = 01 | 0200 = 0201

The bitmask values in `m_ctype.h' are octal values, but the elements of
the `ctype' array in `MYSET.xml' should be written as hexadecimal
values.

The `lower' and `upper' arrays hold the lowercase and uppercase
characters corresponding to each member of the character set. For
example:

     lower['A'] should contain 'a'
     upper['a'] should contain 'A'

Each `collation' array is a map indicating how characters should be
ordered for comparison and sorting purposes. MySQL sorts characters
based on the values of this information. In some cases, this is the
same as the `upper' array, which means that sorting is
case-insensitive. For more complicated sorting rules (for complex
character sets), see the discussion of string collating in *Note
string-collating::.


File: manual.info,  Node: string-collating,  Next: multi-byte-characters,  Prev: character-arrays,  Up: adding-character-set

9.4.2 String Collating Support
------------------------------

For simple character sets, sorting rules are specified in the
`MYSET.xml' configuration file using `<map>' array elements within
`<collation>' elements.  If the sorting rules for your language are too
complex to be handled with simple arrays, you need to define string
collating functions in the `ctype-MYSET.c' source file in the `strings'
directory.

The existing character sets provide the best documentation and examples
to show how these functions are implemented. Look at the `ctype-*.c'
files in the `strings' directory, such as the files for the `big5',
`czech', `gbk', `sjis', and `tis160' character sets. Take a look at the
`MY_COLLATION_HANDLER' structures to see how they are used, and see the
`CHARSET_INFO.txt' file in the `strings' directory for additional
information.


File: manual.info,  Node: multi-byte-characters,  Prev: string-collating,  Up: adding-character-set

9.4.3 Multi-Byte Character Support
----------------------------------

If you want to add support for a new character set that includes
multi-byte characters, you need to use multi-byte character functions
in the `ctype-MYSET.c' source file in the `strings' directory.

The existing character sets provide the best documentation and examples
to show how these functions are implemented. Look at the `ctype-*.c'
files in the `strings' directory, such as the files for the `euc_kr',
`gb2312', `gbk', `sjis', and `ujis' character sets. Take a look at the
`MY_CHARSET_HANDLER' structures to see how they are used, and see the
`CHARSET_INFO.txt' file in the `strings' directory for additional
information.


File: manual.info,  Node: adding-collation,  Next: problems-with-character-sets,  Prev: adding-character-set,  Up: internationalization-localization

9.5 How to Add a New Collation to a Character Set
=================================================

* Menu:

* charset-collation-implementations::  Collation Implementation Types
* adding-collation-choosing-id::  Choosing a Collation ID
* adding-collation-simple-8bit::  Adding a Simple Collation to an 8-Bit Character Set
* adding-collation-unicode-uca::  Adding a UCA Collation to a Unicode Character Set

A collation is a set of rules that defines how to compare and sort
character strings. Each collation in MySQL belongs to a single
character set. Every character set has at least one collation, and most
have two or more collations.

A collation orders characters based on weights. Each character in a
character set maps to a weight. Characters with equal weights compare
as equal, and characters with unequal weights compare according to the
relative magnitude of their weights.

The `WEIGHT_STRING()' function can be used to see the weights for the
characters in a string. The value that it returns to indicate weights
is a binary string, so it is convenient to use `HEX(WEIGHT_STRING(STR))'
to display the weights in printable form. The following example shows
that weights do not differ for lettercase for the letters in `'AaBb''
it if is a non-binary case-insensitive string, but do differ if it is a
binary string:

     mysql> SELECT HEX(WEIGHT_STRING('AaBb' COLLATE latin1_swedish_ci));
     +------------------------------------------------------+
     | HEX(WEIGHT_STRING('AaBb' COLLATE latin1_swedish_ci)) |
     +------------------------------------------------------+
     | 41414242                                             |
     +------------------------------------------------------+
     mysql> SELECT HEX(WEIGHT_STRING(BINARY 'AaBb'));
     +-----------------------------------+
     | HEX(WEIGHT_STRING(BINARY 'AaBb')) |
     +-----------------------------------+
     | 41614262                          |
     +-----------------------------------+

MySQL supports several collation implementations, as discussed in *Note
charset-collation-implementations::. Some of these can be added to
MySQL without recompiling:

   * Simple collations for 8-bit character sets

   * UCA-based collations for Unicode character sets

   * Binary (`XXX_bin') collations

The following discussion describes how to add collations of the first
two types to existing character sets. All existing character sets
already have a binary collation, so there is no need here to describe
how to add one.

Summary of the procedure for adding a new collation:

  1. Choose a collation ID

  2. Add configuration information that names the collation and
     describes the character-ordering rules

  3. Restart the server

  4. Verify that the collation is present

The instructions here cover only collations that can be added without
recompiling MySQL. To add a collation that does require recompiling (as
implemented by means of functions in a C source file), use the
instructions in *Note adding-character-set::. However, instead of adding
all the information required for a complete character set, just modify
the appropriate files for an existing character set. That is, based on
what is already present for the character set's current collations, add
new data structures, functions, and configuration information for the
new collation. For an example, see the MySQL Blog article in the
following list of additional resources.

*Additional resources*

   * The Unicode Collation Algorithm (UCA) specification:
     `http://www.unicode.org/reports/tr10/'

   * The Locale Data Markup Language (LDML) specification:
     `http://www.unicode.org/reports/tr35/'

   * MySQL University session `How to Add a Collation':
     `http://forge.mysql.com/wiki/How_to_Add_a_Collation'

   * MySQL Blog article `Instructions for adding a new Unicode
     collation':
     `http://blogs.mysql.com/peterg/2008/05/19/instructions-for-adding-a-new-unicode-collation/'


File: manual.info,  Node: charset-collation-implementations,  Next: adding-collation-choosing-id,  Prev: adding-collation,  Up: adding-collation

9.5.1 Collation Implementation Types
------------------------------------

MySQL implements several types of collations:

*Simple collations for 8-bit character sets*

This kind of collation is implemented using an array of 256 weights
that defines a one-to-one mapping from character codes to weights.
`latin1_swedish_ci' is an example.  It is a case-insensitive collation,
so the uppercase and lowercase versions of a character have the same
weights and they compare as equal.

     mysql> SET NAMES 'latin1' COLLATE 'latin1_swedish_ci';
     Query OK, 0 rows affected (0.01 sec)

     mysql> SELECT HEX(WEIGHT_STRING('a')), HEX(WEIGHT_STRING('A'));
     +-------------------------+-------------------------+
     | HEX(WEIGHT_STRING('a')) | HEX(WEIGHT_STRING('A')) |
     +-------------------------+-------------------------+
     | 41                      | 41                      |
     +-------------------------+-------------------------+
     1 row in set (0.01 sec)

     mysql> SELECT 'a' = 'A';
     +-----------+
     | 'a' = 'A' |
     +-----------+
     |         1 |
     +-----------+
     1 row in set (0.12 sec)

*Complex collations for 8-bit character sets*

This kind of collation is implemented using functions in a C source
file that define how to order characters, as described in *Note
adding-character-set::.

*Collations for non-Unicode multi-byte character sets*

For this type of collation, 8-bit (single-byte) and multi-byte
characters are handled differently. For 8-bit characters, character
codes map to weights in case-insensitive fashion. (For example, the
single-byte characters `'a'' and `'A'' both have a weight of `0x41'.)
For multi-byte characters, there are two types of relationship between
character codes and weights:

   * Weights equal character codes.  `sjis_japanese_ci' is an example
     of this kind of collation. The multi-byte character `'ぢ'' has a
     character code of `0x82C0', and the weight is also `0x82C0'.

          mysql> CREATE TABLE t1
              -> (c1 VARCHAR(2) CHARACTER SET sjis COLLATE sjis_japanese_ci);
          Query OK, 0 rows affected (0.01 sec)

          mysql> INSERT INTO t1 VALUES ('a'),('A'),(0x82C0);
          Query OK, 3 rows affected (0.00 sec)
          Records: 3  Duplicates: 0  Warnings: 0

          mysql> SELECT c1, HEX(c1), HEX(WEIGHT_STRING(c1)) FROM t1;
          +------+---------+------------------------+
          | c1   | HEX(c1) | HEX(WEIGHT_STRING(c1)) |
          +------+---------+------------------------+
          | a    | 61      | 41                     |
          | A    | 41      | 41                     |
          | ぢ    | 82C0    | 82C0                   |
          +------+---------+------------------------+
          3 rows in set (0.00 sec)

   * Character codes map one-to-one to weights, but a code is not
     necessarily equal to the weight.  `gbk_chinese_ci' is an example
     of this kind of collation. The multi-byte character `'膰'' has a
     character code of `0x81B0' but a weight of `0xC286'.

          mysql> CREATE TABLE t1
              -> (c1 VARCHAR(2) CHARACTER SET gbk COLLATE gbk_chinese_ci);
          Query OK, 0 rows affected (0.33 sec)

          mysql> INSERT INTO t1 VALUES ('a'),('A'),(0x81B0);
          Query OK, 3 rows affected (0.00 sec)
          Records: 3  Duplicates: 0  Warnings: 0

          mysql> SELECT c1, HEX(c1), HEX(WEIGHT_STRING(c1)) FROM t1;
          +------+---------+------------------------+
          | c1   | HEX(c1) | HEX(WEIGHT_STRING(c1)) |
          +------+---------+------------------------+
          | a    | 61      | 41                     |
          | A    | 41      | 41                     |
          | 膰    | 81B0    | C286                   |
          +------+---------+------------------------+
          3 rows in set (0.00 sec)

*Collations for Unicode multi-byte character sets*

Some of these collations are based on the Unicode Collation Algorithm
(UCA), others are not.

Non-UCA collations have a one-to-one mapping from character code to
weight. In MySQL, such collations are case insensitive and accent
insensitive. `utf8_general_ci' is an example: `'a'', `'A'', `'A`'', and
`'a''' each have different character codes but all have a weight of
`0x0041' and compare as equal.

     mysql> SET NAMES 'utf8' COLLATE 'utf8_general_ci';
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t1
         -> (c1 CHAR(1) CHARACTER SET UTF8 COLLATE utf8_general_ci);
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO t1 VALUES ('a'),('A'),('A`'),('a'');
     Query OK, 4 rows affected (0.00 sec)
     Records: 4  Duplicates: 0  Warnings: 0

     mysql> SELECT c1, HEX(c1), HEX(WEIGHT_STRING(c1)) FROM t1;
     +------+---------+------------------------+
     | c1   | HEX(c1) | HEX(WEIGHT_STRING(c1)) |
     +------+---------+------------------------+
     | a    | 61      | 0041                   |
     | A    | 41      | 0041                   |
     | A`    | C380    | 0041                   |
     | a'    | C3A1    | 0041                   |
     +------+---------+------------------------+
     4 rows in set (0.00 sec)

UCA-based collations in MySQL have these properties:

   * If a character has weights, each weight uses 2 bytes (16 bits)

   * A character may have zero weights (or an empty weight). In this
     case, the character is ignorable. Example: "U+0000 NULL" does not
     have a weight and is ignorable.

   * A character may have one weight. Example: `'a'' has a weight of
     `0x0E33'.

          mysql> SET NAMES 'utf8' COLLATE 'utf8_unicode_ci';
          Query OK, 0 rows affected (0.05 sec)

          mysql> SELECT HEX('a'), HEX(WEIGHT_STRING('a'));
          +----------+-------------------------+
          | HEX('a') | HEX(WEIGHT_STRING('a')) |
          +----------+-------------------------+
          | 61       | 0E33                    |
          +----------+-------------------------+
          1 row in set (0.02 sec)

   * A character may have many weights. This is an expansion.  Example:
     The German letter `'ss'' (SZ LEAGUE, or SHARP S) has a weight of
     `0x0FEA0FEA'.

          mysql> SET NAMES 'utf8' COLLATE 'utf8_unicode_ci';
          Query OK, 0 rows affected (0.11 sec)

          mysql> SELECT HEX('ss'), HEX(WEIGHT_STRING('ss'));
          +-----------+--------------------------+
          | HEX('ss')  | HEX(WEIGHT_STRING('ss'))  |
          +-----------+--------------------------+
          | C39F      | 0FEA0FEA                 |
          +-----------+--------------------------+
          1 row in set (0.00 sec)

   * Many characters may have one weight. This is a contraction.
     Example: `'ch'' is a single letter in Czech and has a weight of
     `0x0EE2'.

          mysql> SET NAMES 'utf8' COLLATE 'utf8_czech_ci';
          Query OK, 0 rows affected (0.09 sec)

          mysql> SELECT HEX('ch'), HEX(WEIGHT_STRING('ch'));
          +-----------+--------------------------+
          | HEX('ch') | HEX(WEIGHT_STRING('ch')) |
          +-----------+--------------------------+
          | 6368      | 0EE2                     |
          +-----------+--------------------------+
          1 row in set (0.00 sec)

A many-characters-to-many-weights mapping is also possible (this is
contraction with expansion), but is not supported by MySQL.

*Miscellaneous collations*

There are also a few collations that do not fall into any of the
previous categories.


File: manual.info,  Node: adding-collation-choosing-id,  Next: adding-collation-simple-8bit,  Prev: charset-collation-implementations,  Up: adding-collation

9.5.2 Choosing a Collation ID
-----------------------------

Each collation must have a unique ID. To add a new collation, you must
choose an ID value that is not currently used. As of MySQL 6.0.8, the
range of IDs from 1024 to 2047 is reserved for user-defined collations.
Before 6.0.8, the ID must be chosen from the range 1 to 254. The
collation ID that you choose will show up in these contexts:

   * The `Id' column of *Note `SHOW COLLATION': show-collation. output

   * The `ID' column of the *Note `INFORMATION_SCHEMA.COLLATIONS':
     collations-table.  table

   * The `charsetnr' member of the `MYSQL_FIELD' C API data structure

   * The `number' member of the `MY_CHARSET_INFO' data structure
     returned by the *Note `mysql_get_character_set_info()':
     mysql-get-character-set-info.  C API function

To determine the largest currently used ID, issue the following
statement:

     mysql> SELECT MAX(ID) FROM INFORMATION_SCHEMA.COLLATIONS;
     +---------+
     | MAX(ID) |
     +---------+
     |     210 |
     +---------+

To display a list of all currently used IDs, issue this statement:

     mysql> SELECT ID FROM INFORMATION_SCHEMA.COLLATIONS ORDER BY ID;
     +-----+
     | ID  |
     +-----+
     |   1 |
     |   2 |
     | ... |
     |  52 |
     |  53 |
     |  57 |
     |  58 |
     | ... |
     |  98 |
     |  99 |
     | 128 |
     | 129 |
     | ... |
     | 210 |
     +-----+

*Warning*:

Before MySQL 6.0.8, which provides for a range of user-defined
collation IDs, you must choose an ID in the range from 1 to 254. In
this case, if you upgrade MySQL, you may find that the collation ID you
choose has been assigned to a collation included in the new MySQL
distribution. In this case, you will need to choose a new value for
your own collation.

In addition, before upgrading, you should save the configuration files
that you change. If you upgrade in place, the process will replace the
your modified files.


File: manual.info,  Node: adding-collation-simple-8bit,  Next: adding-collation-unicode-uca,  Prev: adding-collation-choosing-id,  Up: adding-collation

9.5.3 Adding a Simple Collation to an 8-Bit Character Set
---------------------------------------------------------

To add a simple collation for an 8-bit character set without
recompiling MySQL, use the following procedure. The example adds a
collation named `latin1_test_ci' to the `latin1' character set.

  1. Choose a collation ID, as shown in *Note
     adding-collation-choosing-id::. The following steps use an ID of
     1024.

  2. You will need to modify the `Index.xml' and `latin1.xml'
     configuration files. These files will be located in the directory
     named by the `character_sets_dir' system variable. You can check
     the variable value as follows, although the path name might be
     different on your system:

          mysql> SHOW VARIABLES LIKE 'character_sets_dir';
          +--------------------+-----------------------------------------+
          | Variable_name      | Value                                   |
          +--------------------+-----------------------------------------+
          | character_sets_dir | /user/local/mysql/share/mysql/charsets/ |
          +--------------------+-----------------------------------------+

  3. Choose a name for the collation and list it in the `Index.xml'
     file. Find the `<charset>' element for the character set to which
     the collation is being added, and add a `<collation>' element that
     indicates the collation name and ID. For example:

          <charset name="latin1">
            ...
            <!-- associate collation name with its ID -->
            <collation name="latin1_test_ci" id="1024"/>
            ...
          </charset>

  4. In the `latin1.xml' configuration file, add a `<collation>'
     element that names the collation and that contains a `<map>'
     element that defines a character code-to-weight mapping table.
     Each word within the `<map>' element must be a number in
     hexadecimal format.

          <collation name="latin1_test_ci">
          <map>
           00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
           10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F
           20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F
           30 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F
           40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F
           50 51 52 53 54 55 56 57 58 59 5A 5B 5C 5D 5E 5F
           60 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F
           50 51 52 53 54 55 56 57 58 59 5A 7B 7C 7D 7E 7F
           80 81 82 83 84 85 86 87 88 89 8A 8B 8C 8D 8E 8F
           90 91 92 93 94 95 96 97 98 99 9A 9B 9C 9D 9E 9F
           A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 AA AB AC AD AE AF
           B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 BA BB BC BD BE BF
           41 41 41 41 5B 5D 5B 43 45 45 45 45 49 49 49 49
           44 4E 4F 4F 4F 4F 5C D7 5C 55 55 55 59 59 DE DF
           41 41 41 41 5B 5D 5B 43 45 45 45 45 49 49 49 49
           44 4E 4F 4F 4F 4F 5C F7 5C 55 55 55 59 59 DE FF
          </map>
          </collation>

  5. Restart the server and use this statement to verify that the
     collation is present:

          mysql> SHOW COLLATION LIKE 'latin1_test_ci';
          +----------------+---------+------+---------+----------+---------+
          | Collation      | Charset | Id   | Default | Compiled | Sortlen |
          +----------------+---------+------+---------+----------+---------+
          | latin1_test_ci | latin1  | 1024 |         |          |       1 |
          +----------------+---------+------+---------+----------+---------+


File: manual.info,  Node: adding-collation-unicode-uca,  Prev: adding-collation-simple-8bit,  Up: adding-collation

9.5.4 Adding a UCA Collation to a Unicode Character Set
-------------------------------------------------------

UCA collations for Unicode character sets can be added to MySQL without
recompiling by using a subset of the Locale Data Markup Language
(LDML), which is available at `http://www.unicode.org/reports/tr35/'. In
6.0, this method of adding collations is supported as of MySQL 6.0.4.
With this method, you begin with an existing `base' collation. Then you
describe the new collation in terms of how it differs from the base
collation, rather than defining the entire collation. The following
table lists the base collations for the Unicode character sets.

*Character Set*        *Base Collation*
`utf8'                 `utf8_unicode_ci'
`ucs2'                 `ucs2_unicode_ci'
`utf16'                `utf16_unicode_ci'
`utf32'                `utf32_unicode_ci'

The following brief summary describes the LDML characteristics required
for understanding the procedure for adding a collation given later in
this section:

   * LDML has reset, shift, and identity rules.

   * Characters named in these rules can be written in `\uNNNN' format,
     where NNNN is the hexadecimal Unicode code point value. Basic
     Latin letters `A-Z' and `a-z' can also be written literally (this
     is a MySQL limitation; the LDML specification allows literal
     non-Latin1 characters in the rules). Only characters in the Basic
     Multilingual Plane can be specified. This notation does not apply
     to characters outside the BMP range of `0000' to `FFFF'.

   * A reset rule does not specify any ordering in and of itself.
     Instead, it `resets' the ordering for subsequent shift rules to
     cause them to be taken in relation to a given character. Either of
     the following rules resets subsequent shift rules to be taken in
     relation to the letter `'A'':

          <reset>A</reset>

          <reset>\u0041</reset>

   * Shift rules define primary, secondary, and tertiary differences of
     a character from another character. They are specified using `<p>',
     `<s>', and `<t>' elements. Either of the following rules specifies
     a primary shift rule for the `'G'' character:

          <p>G</p>

          <p>\u0047</p>

        * Use primary differences to distinguish separate letters.

        * Use secondary differences to distinguish accent variations.

        * Use tertiary differences to distinguish lettercase variations.

   * Identity rules indicate that one character sorts identically to
     another. The following rules cause `'b'' sort the same as `'a'':

          <reset>a</reset>
          <i>b</i>

     Identity rules are supported as of MySQL 6.0.9. Prior to 6.0.9,
     use `<s> ... </s>' instead.

To add a UCA collation for a Unicode character set without recompiling
MySQL, use the following procedure. The example adds a collation named
`utf8_phone_ci' to the `utf8' character set. The collation is designed
for a scenario involving a Web application for which users post their
names and phone numbers. Phone numbers can be given in very different
formats:

     +7-12345-67
     +7-12-345-67
     +7 12 345 67
     +7 (12) 345 67
     +71234567

The problem raised by dealing with these kinds of values is that the
varying allowable formats make searching for a specific phone number
very difficult. The solution is to define a new collation that reorders
punctuation characters, making them ignorable.

  1. Choose a collation ID, as shown in *Note
     adding-collation-choosing-id::. The following steps use an ID of
     1029.

  2. You will need to modify the `Index.xml' configuration file. This
     file will be located in the directory named by the
     `character_sets_dir' system variable. You can check the variable
     value as follows, although the path name might be different on
     your system:

          mysql> SHOW VARIABLES LIKE 'character_sets_dir';
          +--------------------+-----------------------------------------+
          | Variable_name      | Value                                   |
          +--------------------+-----------------------------------------+
          | character_sets_dir | /user/local/mysql/share/mysql/charsets/ |
          +--------------------+-----------------------------------------+

  3. Choose a name for the collation and list it in the `Index.xml'
     file. In addition, you'll need to provide the collation ordering
     rules. Find the `<charset>' element for the character set to which
     the collation is being added, and add a `<collation>' element that
     indicates the collation name and ID. Within the `<collation>'
     element, provide a `<rules>' element containing the ordering rules:

          <charset name="utf8">
            ...
            <!-- associate collation name with its ID -->
            <collation name="utf8_phone_ci" id="1029">
              <rules>
                <reset>\u0000</reset>
                  <i>\u0020</i> <!-- space -->
                  <i>\u0028</i> <!-- left parenthesis -->
                  <i>\u0029</i> <!-- right parenthesis -->
                  <i>\u002B</i> <!-- plus -->
                  <i>\u002D</i> <!-- hyphen -->
              </rules>
            </collation>
            ...
          </charset>

  4. If you want a similar collation for other Unicode character sets,
     add other `<collation>' elements. For example, to define
     `ucs2_phone_ci', add a `<collation>' element to the `<charset
     name="ucs2">' element.  Remember that each collation must have its
     own unique ID.

  5. Restart the server and use this statement to verify that the
     collation is present:

          mysql> SHOW COLLATION LIKE 'utf8_phone_ci';
          +---------------+---------+------+---------+----------+---------+
          | Collation     | Charset | Id   | Default | Compiled | Sortlen |
          +---------------+---------+------+---------+----------+---------+
          | utf8_phone_ci | utf8    | 1029 |         |          |       8 |
          +---------------+---------+------+---------+----------+---------+

Now we can test the collation to make sure that it has the desired
properties.

Create a table containing some sample phone numbers using the new
collation:

     mysql> CREATE TABLE phonebook (
         ->   name VARCHAR(64),
         ->   phone VARCHAR(64) CHARACTER SET utf8 COLLATE utf8_phone_ci
         -> );
     Query OK, 0 rows affected (0.09 sec)

     mysql> INSERT INTO phonebook VALUES ('Svoj','+7 912 800 80 02');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO phonebook VALUES ('Hf','+7 (912) 800 80 04');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO phonebook VALUES ('Bar','+7-912-800-80-01');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO phonebook VALUES ('Ramil','(7912) 800 80 03');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO phonebook VALUES ('Sanja','+380 (912) 8008005');
     Query OK, 1 row affected (0.00 sec)

Run some queries to see whether the ignored punctuation characters are
in fact ignored for sorting and comparisons:

     mysql> SELECT * FROM phonebook ORDER BY phone;
     +-------+--------------------+
     | name  | phone              |
     +-------+--------------------+
     | Sanja | +380 (912) 8008005 |
     | Bar   | +7-912-800-80-01   |
     | Svoj  | +7 912 800 80 02   |
     | Ramil | (7912) 800 80 03   |
     | Hf    | +7 (912) 800 80 04 |
     +-------+--------------------+
     5 rows in set (0.00 sec)

     mysql> SELECT * FROM phonebook WHERE phone='+7(912)800-80-01';
     +------+------------------+
     | name | phone            |
     +------+------------------+
     | Bar  | +7-912-800-80-01 |
     +------+------------------+
     1 row in set (0.00 sec)

     mysql> SELECT * FROM phonebook WHERE phone='79128008001';
     +------+------------------+
     | name | phone            |
     +------+------------------+
     | Bar  | +7-912-800-80-01 |
     +------+------------------+
     1 row in set (0.00 sec)

     mysql> SELECT * FROM phonebook WHERE phone='7 9 1 2 8 0 0 8 0 0 1';
     +------+------------------+
     | name | phone            |
     +------+------------------+
     | Bar  | +7-912-800-80-01 |
     +------+------------------+
     1 row in set (0.00 sec)


File: manual.info,  Node: problems-with-character-sets,  Next: time-zone-support,  Prev: adding-collation,  Up: internationalization-localization

9.6 Problems With Character Sets
================================

If you try to use a character set that is not compiled into your
binary, you might run into the following problems:

   * Your program uses an incorrect path to determine where the
     character sets are stored (which is typically the
     `share/mysql/charsets' or `share/charsets' directory under the
     MySQL installation directory). This can be fixed by using the
     `--character-sets-dir' option when you run the program in
     question. For example, to specify a directory to be used by MySQL
     client programs, list it in the `[client]' group of your option
     file. The examples given here show what the setting might look
     like for Unix or Windows, respectively:

          [client]
          character-sets-dir=/usr/local/mysql/share/mysql/charsets

          [client]
          character-sets-dir="C:/Program Files/MySQL/MySQL Server 6.0/share/charsets"

   * The character set is a complex character set that cannot be loaded
     dynamically. In this case, you must recompile the program with
     support for the character set.

     For Unicode character sets, you can define collations without
     recompiling by using LDML notation. See *Note
     adding-collation-unicode-uca::.

   * The character set is a dynamic character set, but you do not have
     a configuration file for it. In this case, you should install the
     configuration file for the character set from a new MySQL
     distribution.

   * If your character set index file does not contain the name for the
     character set, your program displays an error message. The file is
     named `Index.xml' and the message is:

          Character set 'CHARSET_NAME' is not a compiled character set and is not
          specified in the '/usr/share/mysql/charsets/Index.xml' file

     To solve this problem, you should either get a new index file or
     manually add the name of any missing character sets to the current
     file.

For `MyISAM' tables, you can check the character set name and number
for a table with *Note `myisamchk -dvv TBL_NAME': myisamchk.


File: manual.info,  Node: time-zone-support,  Next: locale-support,  Prev: problems-with-character-sets,  Up: internationalization-localization

9.7 MySQL Server Time Zone Support
==================================

* Menu:

* time-zone-upgrades::           Staying Current with Time Zone Changes
* time-zone-leap-seconds::       Time Zone Leap Second Support

The MySQL server maintains several time zone settings:

   * The system time zone. When the server starts, it attempts to
     determine the time zone of the host machine and uses it to set the
     `system_time_zone' system variable. The value does not change
     thereafter.

     You can set the system time zone for MySQL Server at startup with
     the `--timezone=TIMEZONE_NAME' option to *Note `mysqld_safe':
     mysqld-safe. You can also set it by setting the `TZ' environment
     variable before you start *Note `mysqld': mysqld. The allowable
     values for `--timezone' or `TZ' are system-dependent. Consult your
     operating system documentation to see what values are acceptable.

   * The server's current time zone. The global `time_zone' system
     variable indicates the time zone the server currently is operating
     in.  The initial value for `time_zone' is `'SYSTEM'', which
     indicates that the server time zone is the same as the system time
     zone.

     The initial global server time zone value can be specified
     explicitly at startup with the `--default-time-zone=TIMEZONE'
     option on the command line, or you can use the following line in
     an option file:

          default-time-zone='TIMEZONE'

     If you have the `SUPER' privilege, you can set the global server
     time zone value at runtime with this statement:

          mysql> SET GLOBAL time_zone = TIMEZONE;

   * Per-connection time zones. Each client that connects has its own
     time zone setting, given by the session `time_zone' variable.
     Initially, the session variable takes its value from the global
     `time_zone' variable, but the client can change its own time zone
     with this statement:

          mysql> SET time_zone = TIMEZONE;

The current session time zone setting affects display and storage of
time values that are zone-sensitive. This includes the values displayed
by functions such as `NOW()' or `CURTIME()', and values stored in and
retrieved from *Note `TIMESTAMP': datetime. columns.  Values for *Note
`TIMESTAMP': datetime. columns are converted from the current time zone
to UTC for storage, and from UTC to the current time zone for retrieval.

The current time zone setting does not affect values displayed by
functions such as `UTC_TIMESTAMP()' or values in *Note `DATE': datetime,
*Note `TIME': time, or *Note `DATETIME': datetime. columns. Nor are
values in those data types stored in UTC; the time zone applies for them
only when converting from `TIMESTAMP' values. If you want
locale-specific arithmetic for *Note `DATE': datetime, *Note `TIME':
time, or *Note `DATETIME': datetime. values, convert them to UTC,
perform the arithmetic, and then convert back.

The current values of the global and client-specific time zones can be
retrieved like this:

     mysql> SELECT @@global.time_zone, @@session.time_zone;

TIMEZONE values can be given in several formats, none of which are case
sensitive:

   * The value `'SYSTEM'' indicates that the time zone should be the
     same as the system time zone.

   * The value can be given as a string indicating an offset from UTC,
     such as `'+10:00'' or `'-6:00''.

   * The value can be given as a named time zone, such as
     `'Europe/Helsinki'', `'US/Eastern'', or `'MET''.  Named time zones
     can be used only if the time zone information tables in the
     `mysql' database have been created and populated.

The MySQL installation procedure creates the time zone tables in the
`mysql' database, but does not load them. You must do so manually using
the following instructions. (If you are upgrading to MySQL 4.1.3 or
later from an earlier version, you can create the tables by upgrading
your `mysql' database. Use the instructions in *Note mysql-upgrade::.
After creating the tables, you can load them.)

*Note*:

Loading the time zone information is not necessarily a one-time
operation because the information changes occasionally. For example,
the rules for Daylight Saving Time in the United States, Mexico, and
parts of Canada changed in 2007. When such changes occur, applications
that use the old rules become out of date and you may find it necessary
to reload the time zone tables to keep the information used by your
MySQL server current. See the notes at the end of this section.

If your system has its own _zoneinfo_ database (the set of files
describing time zones), you should use the *Note `mysql_tzinfo_to_sql':
mysql-tzinfo-to-sql. program for filling the time zone tables. Examples
of such systems are Linux, FreeBSD, Sun Solaris, and Mac OS X. One
likely location for these files is the `/usr/share/zoneinfo' directory.
If your system does not have a zoneinfo database, you can use the
downloadable package described later in this section.

The *Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql. program is used
to load the time zone tables. On the command line, pass the zoneinfo
directory path name to *Note `mysql_tzinfo_to_sql':
mysql-tzinfo-to-sql. and send the output into the *Note `mysql': mysql.
program. For example:

     shell> mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root mysql

*Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql. reads your system's
time zone files and generates SQL statements from them.  *Note `mysql':
mysql. processes those statements to load the time zone tables.

*Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql. also can be used to
load a single time zone file or to generate leap second information:

   * To load a single time zone file TZ_FILE that corresponds to a time
     zone name TZ_NAME, invoke *Note `mysql_tzinfo_to_sql':
     mysql-tzinfo-to-sql. like this:

          shell> mysql_tzinfo_to_sql TZ_FILE TZ_NAME | mysql -u root mysql

     With this approach, you must execute a separate command to load
     the time zone file for each named zone that the server needs to
     know about.

   * If your time zone needs to account for leap seconds, initialize
     the leap second information like this, where TZ_FILE is the name
     of your time zone file:

          shell> mysql_tzinfo_to_sql --leap TZ_FILE | mysql -u root mysql

   * After running *Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql, it
     is best to restart the server so that it does not continue to use
     any previously cached time zone data.

If your system is one that has no zoneinfo database (for example,
Windows or HP-UX), you can use the package of pre-built time zone
tables that is available for download at the MySQL Developer Zone:

     `http://dev.mysql.com/downloads/timezones.html'

This time zone package contains `.frm', `.MYD', and `.MYI' files for
the `MyISAM' time zone tables. These tables should be part of the
`mysql' database, so you should place the files in the `mysql'
subdirectory of your MySQL server's data directory. The server should
be stopped while you do this and restarted afterward.

*Warning*:

Do not use the downloadable package if your system has a zoneinfo
database. Use the *Note `mysql_tzinfo_to_sql': mysql-tzinfo-to-sql.
utility instead.  Otherwise, you may cause a difference in datetime
handling between MySQL and other applications on your system.

For information about time zone settings in replication setup, please
see *Note replication-features::.


File: manual.info,  Node: time-zone-upgrades,  Next: time-zone-leap-seconds,  Prev: time-zone-support,  Up: time-zone-support

9.7.1 Staying Current with Time Zone Changes
--------------------------------------------

As mentioned earlier, when the time zone rules change, applications
that use the old rules become out of date. To stay current, it is
necessary to make sure that your system uses current time zone
information is used. For MySQL, there are two factors to consider in
staying current:

   * The operating system time affects the value that the MySQL server
     uses for times if its time zone is set to `SYSTEM'. Make sure that
     your operating system is using the latest time zone information.
     For most operating systems, the latest update or service pack
     prepares your system for the time changes. Check the Web site for
     your operating system vendor for an update that addresses the time
     changes.

   * If you replace the system's `/etc/localtime' timezone file with a
     version that uses rules differing from those in effect at *Note
     `mysqld': mysqld. startup, you should restart *Note `mysqld':
     mysqld. so that it uses the updated rules.  Otherwise, *Note
     `mysqld': mysqld. might not notice when the system changes its
     time.

   * If you use named time zones with MySQL, make sure that the time
     zone tables in the `mysql' database are up to date. If your system
     has its own zoneinfo database, you should reload the MySQL time
     zone tables whenever the zoneinfo database is updated, using the
     instructions given earlier in this section. For systems that do
     not have their own zoneinfo database, check the MySQL Developer
     Zone for updates. When a new update is available, download it and
     use it to replace your current time zone tables. *Note `mysqld':
     mysqld. caches time zone information that it looks up, so after
     replacing the time zone tables, you should restart *Note `mysqld':
     mysqld. to make sure that it does not continue to serve outdated
     time zone data.

If you are uncertain whether named time zones are available, for use
either as the server's time zone setting or by clients that set their
own time zone, check whether your time zone tables are empty. The
following query determines whether the table that contains time zone
names has any rows:

     mysql> SELECT COUNT(*) FROM mysql.time_zone_name;
     +----------+
     | COUNT(*) |
     +----------+
     |        0 |
     +----------+

A count of zero indicates that the table is empty. In this case, no one
can be using named time zones, and you don't need to update the tables.
A count greater than zero indicates that the table is not empty and
that its contents are available to be used for named time zone support.
In this case, you should be sure to reload your time zone tables so
that anyone who uses named time zones will get correct query results.

To check whether your MySQL installation is updated properly for a
change in Daylight Saving Time rules, use a test like the one
following. The example uses values that are appropriate for the 2007
DST 1-hour change that occurs in the United States on March 11 at 2 a.m.

The test uses these two queries:

     SELECT CONVERT_TZ('2007-03-11 2:00:00','US/Eastern','US/Central');
     SELECT CONVERT_TZ('2007-03-11 3:00:00','US/Eastern','US/Central');

The two time values indicate the times at which the DST change occurs,
and the use of named time zones requires that the time zone tables be
used. The desired result is that both queries return the same result
(the input time, converted to the equivalent value in the 'US/Central'
time zone).

Before updating the time zone tables, you would see an incorrect result
like this:

     mysql> SELECT CONVERT_TZ('2007-03-11 2:00:00','US/Eastern','US/Central');
     +------------------------------------------------------------+
     | CONVERT_TZ('2007-03-11 2:00:00','US/Eastern','US/Central') |
     +------------------------------------------------------------+
     | 2007-03-11 01:00:00                                        |
     +------------------------------------------------------------+

     mysql> SELECT CONVERT_TZ('2007-03-11 3:00:00','US/Eastern','US/Central');
     +------------------------------------------------------------+
     | CONVERT_TZ('2007-03-11 3:00:00','US/Eastern','US/Central') |
     +------------------------------------------------------------+
     | 2007-03-11 02:00:00                                        |
     +------------------------------------------------------------+

After updating the tables, you should see the correct result:

     mysql> SELECT CONVERT_TZ('2007-03-11 2:00:00','US/Eastern','US/Central');
     +------------------------------------------------------------+
     | CONVERT_TZ('2007-03-11 2:00:00','US/Eastern','US/Central') |
     +------------------------------------------------------------+
     | 2007-03-11 01:00:00                                        |
     +------------------------------------------------------------+

     mysql> SELECT CONVERT_TZ('2007-03-11 3:00:00','US/Eastern','US/Central');
     +------------------------------------------------------------+
     | CONVERT_TZ('2007-03-11 3:00:00','US/Eastern','US/Central') |
     +------------------------------------------------------------+
     | 2007-03-11 01:00:00                                        |
     +------------------------------------------------------------+


File: manual.info,  Node: time-zone-leap-seconds,  Prev: time-zone-upgrades,  Up: time-zone-support

9.7.2 Time Zone Leap Second Support
-----------------------------------

Before MySQL 6.0.9, if the operating system is configured to return
leap seconds from OS time calls or if the MySQL server uses a time zone
definition that has leap seconds, functions such as `NOW()' could
return a value having a time part that ends with `:59:60' or `:59:61'.
If such values are inserted into a table, they would be dumped as is by
*Note `mysqldump': mysqldump. but considered invalid when reloaded,
leading to backup/restore problems.

As of MySQL 6.0.9, leap second values are returned with a time part
that ends with `:59:59'. This means that a function such as `NOW()' can
return the same value for two or three consecutive seconds during the
leap second. It remains true that literal temporal values having a time
part that ends with `:59:60' or `:59:61' are considered invalid.

If it is necessary to search for *Note `TIMESTAMP': datetime. values
one second before the leap second, anomalous results may be obtained if
you use a comparison with `'YYYY-MM-DD hh:mm:ss'' values:

     mysql> CREATE TABLE t1 (a INT, ts TIMESTAMP DEFAULT NOW(), PRIMARY KEY (ts));
     Query OK, 0 rows affected (0.11 sec)

     mysql> # Simulate NOW() = '2009-01-01 02:59:59'
     mysql> SET timestamp = 1230768022;
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO t1 (a) VALUES (1);
     Query OK, 1 row affected (0.07 sec)

     mysql> # Simulate NOW() = '2009-01-01 02:59:60'
     mysql> SET timestamp = 1230768023;
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO t1 (a) VALUES (2);
     Query OK, 1 row affected (0.02 sec)

     mysql> SELECT * FROM t1;
     +------+---------------------+
     | a    | ts                  |
     +------+---------------------+
     |    1 | 2008-12-31 18:00:22 |
     |    2 | 2008-12-31 18:00:23 |
     +------+---------------------+
     2 rows in set (0.02 sec)

     mysql> SELECT * FROM t1 WHERE ts = '2009-01-01 02:59:59';
     Empty set (0.03 sec)

To work around this, you can use a comparison based on the UTC value
actually stored in column, which has the leap second correction applied:

     mysql> SELECT * FROM t1 WHERE UNIX_TIMESTAMP(ts) = 1230768023;
     +------+---------------------+
     | a    | ts                  |
     +------+---------------------+
     |    2 | 2008-12-31 18:00:23 |
     +------+---------------------+
     1 row in set (0.02 sec)


File: manual.info,  Node: locale-support,  Prev: time-zone-support,  Up: internationalization-localization

9.8 MySQL Server Locale Support
===============================

The locale indicated by the `lc_time_names' system variable controls
the language used to display day and month names and abbreviations.
This variable affects the output from the `DATE_FORMAT()', `DAYNAME()'
and `MONTHNAME()' functions.

Locale names are POSIX-style values such as `'ja_JP'' or `'pt_BR''. The
default value is `'en_US'' regardless of your system's locale setting,
but you can set the value at server startup or set the `GLOBAL' value
if you have the `SUPER' privilege. Any client can examine the value of
`lc_time_names' or set its `SESSION' value to affect the locale for its
own connection.

     mysql> SET NAMES 'utf8';
     Query OK, 0 rows affected (0.09 sec)

     mysql> SELECT @@lc_time_names;
     +-----------------+
     | @@lc_time_names |
     +-----------------+
     | en_US           |
     +-----------------+
     1 row in set (0.00 sec)

     mysql> SELECT DAYNAME('2010-01-01'), MONTHNAME('2010-01-01');
     +-----------------------+-------------------------+
     | DAYNAME('2010-01-01') | MONTHNAME('2010-01-01') |
     +-----------------------+-------------------------+
     | Friday                | January                 |
     +-----------------------+-------------------------+
     1 row in set (0.00 sec)

     mysql> SELECT DATE_FORMAT('2010-01-01','%W %a %M %b');
     +-----------------------------------------+
     | DATE_FORMAT('2010-01-01','%W %a %M %b') |
     +-----------------------------------------+
     | Friday Fri January Jan                  |
     +-----------------------------------------+
     1 row in set (0.00 sec)

     mysql> SET lc_time_names = 'es_MX';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @@lc_time_names;
     +-----------------+
     | @@lc_time_names |
     +-----------------+
     | es_MX           |
     +-----------------+
     1 row in set (0.00 sec)

     mysql> SELECT DAYNAME('2010-01-01'), MONTHNAME('2010-01-01');
     +-----------------------+-------------------------+
     | DAYNAME('2010-01-01') | MONTHNAME('2010-01-01') |
     +-----------------------+-------------------------+
     | viernes               | enero                   |
     +-----------------------+-------------------------+
     1 row in set (0.00 sec)

     mysql> SELECT DATE_FORMAT('2010-01-01','%W %a %M %b');
     +-----------------------------------------+
     | DATE_FORMAT('2010-01-01','%W %a %M %b') |
     +-----------------------------------------+
     | viernes vie enero ene                   |
     +-----------------------------------------+
     1 row in set (0.00 sec)

The day or month name for each of the affected functions is converted
from `utf8' to the character set indicated by the
`character_set_connection' system variable.

`lc_time_names' may be set to any of the following locale values.

`ar_AE': Arabic - United Arab        `ar_BH': Arabic - Bahrain
Emirates                             
`ar_DZ': Arabic - Algeria            `ar_EG': Arabic - Egypt
`ar_IN': Arabic - Iran               `ar_IQ': Arabic - Iraq
`ar_JO': Arabic - Jordan             `ar_KW': Arabic - Kuwait
`ar_LB': Arabic - Lebanon            `ar_LY': Arabic - Libya
`ar_MA': Arabic - Morocco            `ar_OM': Arabic - Oman
`ar_QA': Arabic - Qatar              `ar_SA': Arabic - Saudi Arabia
`ar_SD': Arabic - Sudan              `ar_SY': Arabic - Syria
`ar_TN': Arabic - Tunisia            `ar_YE': Arabic - Yemen
`be_BY': Belarusian - Belarus        `bg_BG': Bulgarian - Bulgaria
`ca_ES': Catalan - Catalan           `cs_CZ': Czech - Czech Republic
`da_DK': Danish - Denmark            `de_AT': German - Austria
`de_BE': German - Belgium            `de_CH': German - Switzerland
`de_DE': German - Germany            `de_LU': German - Luxembourg
`EE': Estonian - Estonia             `en_AU': English - Australia
`en_CA': English - Canada            `en_GB': English - United Kingdom
`en_IN': English - India             `en_NZ': English - New Zealand
`en_PH': English - Philippines       `en_US': English - United States
`en_ZA': English - South Africa      `en_ZW': English - Zimbabwe
`es_AR': Spanish - Argentina         `es_BO': Spanish - Bolivia
`es_CL': Spanish - Chile             `es_CO': Spanish - Columbia
`es_CR': Spanish - Costa Rica        `es_DO': Spanish - Dominican
                                     Republic
`es_EC': Spanish - Ecuador           `es_ES': Spanish - Spain
`es_GT': Spanish - Guatemala         `es_HN': Spanish - Honduras
`es_MX': Spanish - Mexico            `es_NI': Spanish - Nicaragua
`es_PA': Spanish - Panama            `es_PE': Spanish - Peru
`es_PR': Spanish - Puerto Rico       `es_PY': Spanish - Paraguay
`es_SV': Spanish - El Salvador       `es_US': Spanish - United States
`es_UY': Spanish - Uruguay           `es_VE': Spanish - Venezuela
`eu_ES': Basque - Basque             `fi_FI': Finnish - Finland
`fo_FO': Faroese - Faroe Islands     `fr_BE': French - Belgium
`fr_CA': French - Canada             `fr_CH': French - Switzerland
`fr_FR': French - France             `fr_LU': French - Luxembourg
`gl_ES': Galician - Galician         `gu_IN': Gujarati - India
`he_IL': Hebrew - Israel             `hi_IN': Hindi - India
`hr_HR': Croatian - Croatia          `hu_HU': Hungarian - Hungary
`id_ID': Indonesian - Indonesia      `is_IS': Icelandic - Iceland
`it_CH': Italian - Switzerland       `it_IT': Italian - Italy
`ja_JP': Japanese - Japan            `ko_KR': Korean - Korea
`lt_LT': Lithuanian - Lithuania      `lv_LV': Latvian - Latvia
`mk_MK': Macedonian - FYROM          `mn_MN': Mongolia - Mongolian
`ms_MY': Malay - Malaysia            `nb_NO': Norwegian(Bokml) - Norway
`nl_BE': Dutch - Belgium             `nl_NL': Dutch - The Netherlands
`no_NO': Norwegian - Norway          `pl_PL': Polish - Poland
`pt_BR': Portugese - Brazil          `pt_PT': Portugese - Portugal
`ro_RO': Romanian - Romania          `ru_RU': Russian - Russia
`ru_UA': Russian - Ukraine           `sk_SK': Slovak - Slovakia
`sl_SI': Slovenian - Slovenia        `sq_AL': Albanian - Albania
`sr_YU': Serbian - Yugoslavia        `sv_FI': Swedish - Finland
`sv_SE': Swedish - Sweden            `ta_IN': Tamil - India
`te_IN': Telugu - India              `th_TH': Thai - Thailand
`tr_TR': Turkish - Turkey            `uk_UA': Ukrainian - Ukraine
`ur_PK': Urdu - Pakistan             `vi_VN': Vietnamese - Vietnam
`zh_CN': Chinese - Peoples Republic  `zh_HK': Chinese - Hong Kong SAR
of China                             
`zh_TW': Chinese - Taiwan            

`lc_time_names' currently does not affect the `STR_TO_DATE()' or
`GET_FORMAT()' function.


File: manual.info,  Node: data-types,  Next: functions,  Prev: internationalization-localization,  Up: Top

10 Data Types
*************

* Menu:

* data-type-overview::           Data Type Overview
* numeric-types::                Numeric Types
* date-and-time-types::          Date and Time Types
* string-types::                 String Types
* storage-requirements::         Data Type Storage Requirements
* choosing-types::               Choosing the Right Type for a Column
* other-vendor-data-types::      Using Data Types from Other Database Engines

MySQL supports a number of data types in several categories: numeric
types, date and time types, and string (character) types. This chapter
first gives an overview of these data types, and then provides a more
detailed description of the properties of the types in each category,
and a summary of the data type storage requirements. The initial
overview is intentionally brief. The more detailed descriptions later
in the chapter should be consulted for additional information about
particular data types, such as the allowable formats in which you can
specify values.

MySQL also supports extensions for handing spatial data.  *Note
spatial-extensions::, provides information about these data types.

Data type descriptions use these conventions:

   * M indicates the maximum display width for integer types. For
     floating-point and fixed-point types, M is the total number of
     digits that can be stored. For string types, M is the maximum
     length. The maximum allowable value of M depends on the data type.

   * D applies to floating-point and fixed-point types and indicates
     the number of digits following the decimal point. The maximum
     possible value is 30, but should be no greater than M-2.

   * Square brackets (``['' and ``]'') indicate optional parts of type
     definitions.


File: manual.info,  Node: data-type-overview,  Next: numeric-types,  Prev: data-types,  Up: data-types

10.1 Data Type Overview
=======================

* Menu:

* numeric-type-overview::        Overview of Numeric Types
* date-and-time-type-overview::  Overview of Date and Time Types
* string-type-overview::         Overview of String Types
* data-type-defaults::           Data Type Default Values


File: manual.info,  Node: numeric-type-overview,  Next: date-and-time-type-overview,  Prev: data-type-overview,  Up: data-type-overview

10.1.1 Overview of Numeric Types
--------------------------------

A summary of the numeric data types follows. For additional information
about properties of the numeric types, see *Note numeric-types::.
Storage requirements are given in *Note storage-requirements::.

M indicates the maximum display width for integer types. The maximum
legal display width is 255.  Display width is unrelated to the range of
values a type can contain, as described in *Note numeric-types::. For
floating-point and fixed-point types, M is the total number of digits
that can be stored.

If you specify `ZEROFILL' for a numeric column, MySQL automatically
adds the `UNSIGNED' attribute to the column.

Numeric data types that allow the `UNSIGNED' attribute also allow
`SIGNED'. However, these data types are signed by default, so the
`SIGNED' attribute has no effect.

`SERIAL' is an alias for `BIGINT UNSIGNED NOT NULL AUTO_INCREMENT
UNIQUE'.

`SERIAL DEFAULT VALUE' in the definition of an integer column is an
alias for `NOT NULL AUTO_INCREMENT UNIQUE'.

*Warning*:

When you use subtraction between integer values where one is of type
`UNSIGNED', the result is unsigned unless the `NO_UNSIGNED_SUBTRACTION'
SQL mode is enabled. See *Note cast-functions::.

   * `BIT[(M)]'

     A bit-field type. M indicates the number of bits per value, from 1
     to 64. The default is 1 if M is omitted.

   * `TINYINT[(M)] [UNSIGNED] [ZEROFILL]'

     A very small integer. The signed range is `-128' to `127'. The
     unsigned range is `0' to `255'.

   * *Note `BOOL': numeric-types, *Note `BOOLEAN': numeric-types.

     These types are synonyms for `TINYINT(1)'.  A value of zero is
     considered false. Non-zero values are considered true:

          mysql> SELECT IF(0, 'true', 'false');
          +------------------------+
          | IF(0, 'true', 'false') |
          +------------------------+
          | false                  |
          +------------------------+

          mysql> SELECT IF(1, 'true', 'false');
          +------------------------+
          | IF(1, 'true', 'false') |
          +------------------------+
          | true                   |
          +------------------------+

          mysql> SELECT IF(2, 'true', 'false');
          +------------------------+
          | IF(2, 'true', 'false') |
          +------------------------+
          | true                   |
          +------------------------+

     However, the values `TRUE' and `FALSE' are merely aliases for `1'
     and `0', respectively, as shown here:

          mysql> SELECT IF(0 = FALSE, 'true', 'false');
          +--------------------------------+
          | IF(0 = FALSE, 'true', 'false') |
          +--------------------------------+
          | true                           |
          +--------------------------------+

          mysql> SELECT IF(1 = TRUE, 'true', 'false');
          +-------------------------------+
          | IF(1 = TRUE, 'true', 'false') |
          +-------------------------------+
          | true                          |
          +-------------------------------+

          mysql> SELECT IF(2 = TRUE, 'true', 'false');
          +-------------------------------+
          | IF(2 = TRUE, 'true', 'false') |
          +-------------------------------+
          | false                         |
          +-------------------------------+

          mysql> SELECT IF(2 = FALSE, 'true', 'false');
          +--------------------------------+
          | IF(2 = FALSE, 'true', 'false') |
          +--------------------------------+
          | false                          |
          +--------------------------------+

     The last two statements display the results shown because `2' is
     equal to neither `1' nor `0'.

     We intend to implement full boolean type handling, in accordance
     with standard SQL, in a future MySQL release.

   * `SMALLINT[(M)] [UNSIGNED] [ZEROFILL]'

     A small integer. The signed range is `-32768' to `32767'. The
     unsigned range is `0' to `65535'.

   * `MEDIUMINT[(M)] [UNSIGNED] [ZEROFILL]'

     A medium-sized integer. The signed range is `-8388608' to
     `8388607'.  The unsigned range is `0' to `16777215'.

   * `INT[(M)] [UNSIGNED] [ZEROFILL]'

     A normal-size integer. The signed range is `-2147483648' to
     `2147483647'. The unsigned range is `0' to `4294967295'.

   * `INTEGER[(M)] [UNSIGNED] [ZEROFILL]'

     This type is a synonym for *Note `INT': numeric-types.

   * `BIGINT[(M)] [UNSIGNED] [ZEROFILL]'

     A large integer. The signed range is `-9223372036854775808' to
     `9223372036854775807'. The unsigned range is `0' to
     `18446744073709551615'.

     `SERIAL' is an alias for `BIGINT UNSIGNED NOT NULL AUTO_INCREMENT
     UNIQUE'.

     Some things you should be aware of with respect to *Note `BIGINT':
     numeric-types. columns:

        * All arithmetic is done using signed *Note `BIGINT':
          numeric-types. or *Note `DOUBLE': numeric-types. values, so
          you should not use unsigned big integers larger than
          `9223372036854775807' (63 bits) except with bit functions! If
          you do that, some of the last digits in the result may be
          wrong because of rounding errors when converting a *Note
          `BIGINT': numeric-types. value to a *Note `DOUBLE':
          numeric-types.

          MySQL can handle *Note `BIGINT': numeric-types.  in the
          following cases:

             * When using integers to store large unsigned values in a
               *Note `BIGINT': numeric-types. column.

             * In `MIN(COL_NAME)' or `MAX(COL_NAME)', where COL_NAME
               refers to a *Note `BIGINT': numeric-types. column.

             * When using operators (`+', `-', `*', and so on) where
               both operands are integers.

        * You can always store an exact integer value in a *Note
          `BIGINT': numeric-types. column by storing it using a string.
          In this case, MySQL performs a string-to-number conversion
          that involves no intermediate double-precision representation.

        * The `-', `+', and `*' operators use *Note `BIGINT':
          numeric-types.  arithmetic when both operands are integer
          values. This means that if you multiply two big integers (or
          results from functions that return integers), you may get
          unexpected results when the result is larger than
          `9223372036854775807'.

   * `FLOAT[(M,D)] [UNSIGNED] [ZEROFILL]'

     A small (single-precision) floating-point number. Allowable values
     are `-3.402823466E+38' to `-1.175494351E-38', `0', and
     `1.175494351E-38' to `3.402823466E+38'. These are the theoretical
     limits, based on the IEEE standard. The actual range might be
     slightly smaller depending on your hardware or operating system.

     M is the total number of digits and D is the number of digits
     following the decimal point. If M and D are omitted, values are
     stored to the limits allowed by the hardware. A single-precision
     floating-point number is accurate to approximately 7 decimal
     places.

     `UNSIGNED', if specified, disallows negative values.

     Using *Note `FLOAT': numeric-types. might give you some unexpected
     problems because all calculations in MySQL are done with double
     precision. See *Note no-matching-rows::.

   * `DOUBLE[(M,D)] [UNSIGNED] [ZEROFILL]'

     A normal-size (double-precision) floating-point number.  Allowable
     values are `-1.7976931348623157E+308' to
     `-2.2250738585072014E-308', `0', and `2.2250738585072014E-308' to
     `1.7976931348623157E+308'. These are the theoretical limits, based
     on the IEEE standard. The actual range might be slightly smaller
     depending on your hardware or operating system.

     M is the total number of digits and D is the number of digits
     following the decimal point. If M and D are omitted, values are
     stored to the limits allowed by the hardware. A double-precision
     floating-point number is accurate to approximately 15 decimal
     places.

     `UNSIGNED', if specified, disallows negative values.

   * `DOUBLE PRECISION[(M,D)] [UNSIGNED] [ZEROFILL]', `REAL[(M,D)]
     [UNSIGNED] [ZEROFILL]'

     These types are synonyms for *Note `DOUBLE': numeric-types.
     Exception: If the `REAL_AS_FLOAT' SQL mode is enabled, *Note
     `REAL': numeric-types. is a synonym for *Note `FLOAT':
     numeric-types. rather than *Note `DOUBLE': numeric-types.

   * `FLOAT(P) [UNSIGNED] [ZEROFILL]'

     A floating-point number. P represents the precision in bits, but
     MySQL uses this value only to determine whether to use *Note
     `FLOAT': numeric-types. or *Note `DOUBLE': numeric-types. for the
     resulting data type. If P is from 0 to 24, the data type becomes
     *Note `FLOAT': numeric-types. with no M or D values. If P is from
     25 to 53, the data type becomes *Note `DOUBLE': numeric-types.
     with no M or D values. The range of the resulting column is the
     same as for the single-precision *Note `FLOAT': numeric-types. or
     double-precision *Note `DOUBLE': numeric-types. data types
     described earlier in this section.

     `FLOAT(P)' syntax is provided for ODBC compatibility.

   * `DECIMAL[(M[,D])] [UNSIGNED] [ZEROFILL]'

     A packed `exact' fixed-point number.  M is the total number of
     digits (the precision) and D is the number of digits after the
     decimal point (the scale). The decimal point and (for negative
     numbers) the ``-'' sign are not counted in M. If D is 0, values
     have no decimal point or fractional part. The maximum number of
     digits (M) for *Note `DECIMAL': numeric-types. is 65. The maximum
     number of supported decimals (D) is 30. If D is omitted, the
     default is 0. If M is omitted, the default is 10.

     `UNSIGNED', if specified, disallows negative values.

     All basic calculations (`+, -, *, /') with *Note `DECIMAL':
     numeric-types. columns are done with a precision of 65 digits.

   * `DEC[(M[,D])] [UNSIGNED] [ZEROFILL]', `NUMERIC[(M[,D])] [UNSIGNED]
     [ZEROFILL]', `FIXED[(M[,D])] [UNSIGNED] [ZEROFILL]'

     These types are synonyms for *Note `DECIMAL': numeric-types. The
     *Note `FIXED': numeric-types. synonym is available for
     compatibility with other database systems.


File: manual.info,  Node: date-and-time-type-overview,  Next: string-type-overview,  Prev: numeric-type-overview,  Up: data-type-overview

10.1.2 Overview of Date and Time Types
--------------------------------------

A summary of the temporal data types follows. For additional
information about properties of the temporal types, see *Note
date-and-time-types::. Storage requirements are given in *Note
storage-requirements::. Functions that operate on temporal values are
described at *Note date-and-time-functions::.

For the *Note `DATETIME': datetime. and *Note `DATE': datetime. range
descriptions, `supported' means that although earlier values might
work, there is no guarantee.

   * *Note `DATE': datetime.

     A date. The supported range is `'1000-01-01'' to `'9999-12-31''.
     MySQL displays *Note `DATE': datetime. values in `'YYYY-MM-DD''
     format, but allows assignment of values to *Note `DATE': datetime.
     columns using either strings or numbers.

   * *Note `DATETIME': datetime.

     A date and time combination. The supported range is `'1000-01-01
     00:00:00'' to `'9999-12-31 23:59:59''. MySQL displays *Note
     `DATETIME': datetime. values in `'YYYY-MM-DD HH:MM:SS'' format,
     but allows assignment of values to *Note `DATETIME': datetime.
     columns using either strings or numbers.

   * *Note `TIMESTAMP': datetime.

     A timestamp. The range is `'1970-01-01 00:00:01'' UTC to
     `'2038-01-09 03:14:07'' UTC.  *Note `TIMESTAMP': datetime. values
     are stored as the number of seconds since the epoch (`'1970-01-01
     00:00:00'' UTC). A *Note `TIMESTAMP': datetime. cannot represent
     the value `'1970-01-01 00:00:00'' because that is equivalent to 0
     seconds from the epoch and the value 0 is reserved for
     representing `'0000-00-00 00:00:00'', the `zero' *Note
     `TIMESTAMP': datetime. value.

     A *Note `TIMESTAMP': datetime. column is useful for recording the
     date and time of an *Note `INSERT': insert. or *Note `UPDATE':
     update. operation. By default, the first *Note `TIMESTAMP':
     datetime. column in a table is automatically set to the date and
     time of the most recent operation if you do not assign it a value
     yourself. You can also set any *Note `TIMESTAMP': datetime. column
     to the current date and time by assigning it a `NULL' value.
     Variations on automatic initialization and update properties are
     described in *Note timestamp::.

     A *Note `TIMESTAMP': datetime. value is returned as a string in
     the format `'YYYY-MM-DD HH:MM:SS'' with a display width fixed at 19
     characters. To obtain the value as a number, you should add `+0'
     to the timestamp column.

     *Note*:

     The *Note `TIMESTAMP': datetime. format that was used prior to
     MySQL 4.1 is not supported in MySQL 6.0; see `MySQL 3.23, 4.0, 4.1
     Reference Manual' for information regarding the old format.

   * *Note `TIME': time.

     A time. The range is `'-838:59:59'' to `'838:59:59''. MySQL
     displays *Note `TIME': time. values in `'HH:MM:SS'' format, but
     allows assignment of values to *Note `TIME': time. columns using
     either strings or numbers.

   * `YEAR[(2|4)]'

     A year in two-digit or four-digit format. The default is
     four-digit format. In four-digit format, the allowable values are
     `1901' to `2155', and `0000'. In two-digit format, the allowable
     values are `70' to `69', representing years from 1970 to 2069.
     MySQL displays *Note `YEAR': year. values in `YYYY' format, but
     allows you to assign values to *Note `YEAR': year. columns using
     either strings or numbers.

The `SUM()' and `AVG()' aggregate functions do not work with temporal
values. (They convert the values to numbers, which loses the part after
the first non-numeric character.) To work around this problem, you can
convert to numeric units, perform the aggregate operation, and convert
back to a temporal value. Examples:

     SELECT SEC_TO_TIME(SUM(TIME_TO_SEC(TIME_COL))) FROM TBL_NAME;
     SELECT FROM_DAYS(SUM(TO_DAYS(DATE_COL))) FROM TBL_NAME;


File: manual.info,  Node: string-type-overview,  Next: data-type-defaults,  Prev: date-and-time-type-overview,  Up: data-type-overview

10.1.3 Overview of String Types
-------------------------------

A summary of the string data types follows. For additional information
about properties of the string types, see *Note string-types::. Storage
requirements are given in *Note storage-requirements::.

In some cases, MySQL may change a string column to a type different
from that given in a *Note `CREATE TABLE': create-table. or *Note
`ALTER TABLE': alter-table.  statement. See *Note
silent-column-changes::.

MySQL interprets length specifications in character column definitions
in character units. This applies to *Note `CHAR': char, *Note
`VARCHAR': char, and the *Note `TEXT': blob. types.

Column definitions for many string data types can include attributes
that specify the character set or collation of the column. These
attributes apply to the *Note `CHAR': char, *Note `VARCHAR': char, the
*Note `TEXT': blob. types, *Note `ENUM': enum, and *Note `SET': set.
data types:

   * The `CHARACTER SET' attribute specifies the character set, and the
     `COLLATE' attribute specifies a collation for the character set.
     For example:

          CREATE TABLE t
          (
              c1 VARCHAR(20) CHARACTER SET utf8,
              c2 TEXT CHARACTER SET latin1 COLLATE latin1_general_cs
          );

     This table definition creates a column named `c1' that has a
     character set of `utf8' with the default collation for that
     character set, and a column named `c2' that has a character set of
     `latin1' and a case-sensitive collation.

     The rules for assigning the character set and collation when
     either or both of the `CHARACTER SET' and `COLLATE' attributes are
     missing are described in *Note charset-column::.

     `CHARSET' is a synonym for `CHARACTER SET'.

   * Specifying the `CHARACTER SET binary' attribute for a character
     data type causes the column to be created as the corresponding
     binary data type: *Note `CHAR': char. becomes *Note `BINARY':
     binary-varbinary, *Note `VARCHAR': char. becomes *Note
     `VARBINARY': binary-varbinary, and *Note `TEXT': blob. becomes
     *Note `BLOB': blob. For the *Note `ENUM': enum. and *Note `SET':
     set. data types, this does not occur; they are created as
     declared. Suppose that you specify a table using this definition:

          CREATE TABLE t
          (
            c1 VARCHAR(10) CHARACTER SET binary,
            c2 TEXT CHARACTER SET binary,
            c3 ENUM('a','b','c') CHARACTER SET binary
          );

     The resulting table has this definition:

          CREATE TABLE t
          (
            c1 VARBINARY(10),
            c2 BLOB,
            c3 ENUM('a','b','c') CHARACTER SET binary
          );

   * The `ASCII' attribute is shorthand for `CHARACTER SET latin1'.

   * The `UNICODE' attribute is shorthand for `CHARACTER SET ucs2'.

   * The `BINARY' attribute is shorthand for specifying the binary
     collation of the column character set.  In this case, sorting and
     comparison are based on numeric character values.

Character column sorting and comparison are based on the character set
assigned to the column. For the *Note `CHAR': char, *Note `VARCHAR':
char, *Note `TEXT': blob, *Note `ENUM': enum, and *Note `SET': set.
data types, you can declare a column with a binary collation or the
`BINARY' attribute to cause sorting and comparison to use the underlying
character code values rather than a lexical ordering.

*Note charset::, provides additional information about use of character
sets in MySQL.

   * `[NATIONAL] CHAR[(M)] [CHARACTER SET CHARSET_NAME] [COLLATE
     COLLATION_NAME]'

     A fixed-length string that is always right-padded with spaces to
     the specified length when stored.  M represents the column length
     in characters. The range of M is 0 to 255. If M is omitted, the
     length is 1.

     *Note*:

     Trailing spaces are removed when *Note `CHAR': char. values are
     retrieved unless the `PAD_CHAR_TO_FULL_LENGTH' SQL mode is enabled.

     *Note `CHAR': char. is shorthand for *Note `CHARACTER': char.
     *Note `NATIONAL CHAR': char. (or its equivalent short form, *Note
     `NCHAR': char.)  is the standard SQL way to define that a *Note
     `CHAR': char. column should use some predefined character set.
     MySQL 4.1 and up uses `utf8' as this predefined character set.
     *Note charset-national::.

     The *Note `CHAR BYTE': binary-varbinary. data type is an alias for
     the *Note `BINARY': binary-varbinary. data type. This is a
     compatibility feature.

     MySQL allows you to create a column of type `CHAR(0)'. This is
     useful primarily when you have to be compliant with old
     applications that depend on the existence of a column but that do
     not actually use its value. `CHAR(0)' is also quite nice when you
     need a column that can take only two values: A column that is
     defined as `CHAR(0) NULL' occupies only one bit and can take only
     the values `NULL' and `''' (the empty string).

   * `[NATIONAL] VARCHAR(M) [CHARACTER SET CHARSET_NAME] [COLLATE
     COLLATION_NAME]'

     A variable-length string. M represents the maximum column length
     in characters. The range of M is 0 to 65,535. The effective
     maximum length of a *Note `VARCHAR': char. is subject to the
     maximum row size (65,535 bytes, which is shared among all columns)
     and the character set used. For example, `utf8' characters can
     require up to four bytes per character, so a *Note `VARCHAR':
     char. column that uses the `utf8' character set can be declared to
     be a maximum of 16,383 characters.

     MySQL stores *Note `VARCHAR': char. values as a one-byte or
     two-byte length prefix plus data. The length prefix indicates the
     number of bytes in the value. A *Note `VARCHAR': char. column uses
     one length byte if values require no more than 255 bytes, two
     length bytes if values may require more than 255 bytes.

     *Note*:

     MySQL 6.0 follows the standard SQL specification, and does _not_
     remove trailing spaces from *Note `VARCHAR': char. values.

     *Note `VARCHAR': char. is shorthand for *Note `CHARACTER VARYING':
     char.  *Note `NATIONAL VARCHAR': char. is the standard SQL way to
     define that a *Note `VARCHAR': char. column should use some
     predefined character set. MySQL 4.1 and up uses `utf8' as this
     predefined character set.  *Note charset-national::.  *Note
     `NVARCHAR': char. is shorthand for *Note `NATIONAL VARCHAR': char.

   * `BINARY(M)'

     The *Note `BINARY': binary-varbinary. type is similar to the *Note
     `CHAR': char. type, but stores binary byte strings rather than
     non-binary character strings. M represents the column length in
     bytes.

   * `VARBINARY(M)'

     The *Note `VARBINARY': binary-varbinary. type is similar to the
     *Note `VARCHAR': char. type, but stores binary byte strings rather
     than non-binary character strings. M represents the maximum column
     length in bytes.

   * *Note `TINYBLOB': blob.

     A *Note `BLOB': blob. column with a maximum length of 255 (2^8 - 1)
     bytes. Each *Note `TINYBLOB': blob. value is stored using a
     one-byte length prefix that indicates the number of bytes in the
     value.

   * `TINYTEXT [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]'

     A *Note `TEXT': blob. column with a maximum length of 255 (2^8 - 1)
     characters. The effective maximum length is less if the value
     contains multi-byte characters. Each *Note `TINYTEXT': blob. value
     is stored using a one-byte length prefix that indicates the number
     of bytes in the value.

   * `BLOB[(M)]'

     A *Note `BLOB': blob. column with a maximum length of 65,535 (2^16
     - 1) bytes. Each *Note `BLOB': blob. value is stored using a
     two-byte length prefix that indicates the number of bytes in the
     value.

     An optional length M can be given for this type. If this is done,
     MySQL creates the column as the smallest *Note `BLOB': blob. type
     large enough to hold values M bytes long.

   * `TEXT[(M)] [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]'

     A *Note `TEXT': blob. column with a maximum length of 65,535 (2^16
     - 1) characters. The effective maximum length is less if the value
     contains multi-byte characters. Each *Note `TEXT': blob. value is
     stored using a two-byte length prefix that indicates the number of
     bytes in the value.

     An optional length M can be given for this type. If this is done,
     MySQL creates the column as the smallest *Note `TEXT': blob. type
     large enough to hold values M characters long.

   * *Note `MEDIUMBLOB': blob.

     A *Note `BLOB': blob. column with a maximum length of 16,777,215
     (2^24 - 1) bytes. Each *Note `MEDIUMBLOB': blob.  value is stored
     using a three-byte length prefix that indicates the number of
     bytes in the value.

   * `MEDIUMTEXT [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]'

     A *Note `TEXT': blob. column with a maximum length of 16,777,215
     (2^24 - 1) characters. The effective maximum length is less if the
     value contains multi-byte characters. Each *Note `MEDIUMTEXT':
     blob. value is stored using a three-byte length prefix that
     indicates the number of bytes in the value.

   * *Note `LONGBLOB': blob.

     A *Note `BLOB': blob. column with a maximum length of
     4,294,967,295 or 4GB (2^32 - 1) bytes. The effective maximum
     length of *Note `LONGBLOB': blob. columns depends on the
     configured maximum packet size in the client/server protocol and
     available memory. Each *Note `LONGBLOB': blob. value is stored
     using a four-byte length prefix that indicates the number of bytes
     in the value.

   * `LONGTEXT [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]'

     A *Note `TEXT': blob. column with a maximum length of
     4,294,967,295 or 4GB (2^32 - 1) characters. The effective maximum
     length is less if the value contains multi-byte characters. The
     effective maximum length of *Note `LONGTEXT': blob. columns also
     depends on the configured maximum packet size in the client/server
     protocol and available memory. Each *Note `LONGTEXT': blob. value
     is stored using a four-byte length prefix that indicates the
     number of bytes in the value.

   * `ENUM('VALUE1','VALUE2',...)  [CHARACTER SET CHARSET_NAME] [COLLATE
     COLLATION_NAME]'

     An enumeration. A string object that can have only one value,
     chosen from the list of values `'VALUE1'', `'VALUE2'', `...',
     `NULL' or the special `''' error value. An *Note `ENUM': enum.
     column can have a maximum of 65,535 distinct values.  *Note
     `ENUM': enum. values are represented internally as integers.

   * `SET('VALUE1','VALUE2',...)  [CHARACTER SET CHARSET_NAME] [COLLATE
     COLLATION_NAME]'

     A set. A string object that can have zero or more values, each of
     which must be chosen from the list of values `'VALUE1'',
     `'VALUE2'', `...' A *Note `SET': set.  column can have a maximum
     of 64 members.  *Note `SET': set. values are represented
     internally as integers.


File: manual.info,  Node: data-type-defaults,  Prev: string-type-overview,  Up: data-type-overview

10.1.4 Data Type Default Values
-------------------------------

The `DEFAULT VALUE' clause in a data type specification indicates a
default value for a column. With one exception, the default value must
be a constant; it cannot be a function or an expression. This means,
for example, that you cannot set the default for a date column to be
the value of a function such as `NOW()' or `CURRENT_DATE'. The
exception is that you can specify `CURRENT_TIMESTAMP' as the default
for a *Note `TIMESTAMP': datetime. column. See *Note timestamp::.

*Note `BLOB': blob. and *Note `TEXT': blob. columns cannot be assigned a
default value.

If a column definition includes no explicit `DEFAULT' value, MySQL
determines the default value as follows:

If the column can take `NULL' as a value, the column is defined with an
explicit `DEFAULT NULL' clause.

If the column cannot take `NULL' as the value, MySQL defines the column
with no explicit `DEFAULT' clause. For data entry, if an *Note
`INSERT': insert. or *Note `REPLACE': replace. statement includes no
value for the column, or an *Note `UPDATE': update. statement sets the
column to `NULL', MySQL handles the column according to the SQL mode in
effect at the time:

   * If strict SQL mode is not enabled, MySQL sets the column to the
     implicit default value for the column data type.

   * If strict mode is enabled, an error occurs for transactional
     tables and the statement is rolled back. For non-transactional
     tables, an error occurs, but if this happens for the second or
     subsequent row of a multiple-row statement, the preceding rows
     will have been inserted.

Suppose that a table `t' is defined as follows:

     CREATE TABLE t (i INT NOT NULL);

In this case, `i' has no explicit default, so in strict mode each of
the following statements produce an error and no row is inserted. When
not using strict mode, only the third statement produces an error; the
implicit default is inserted for the first two statements, but the
third fails because `DEFAULT(i)' cannot produce a value:

     INSERT INTO t VALUES();
     INSERT INTO t VALUES(DEFAULT);
     INSERT INTO t VALUES(DEFAULT(i));

See *Note server-sql-mode::.

For a given table, you can use the *Note `SHOW CREATE TABLE':
show-create-table. statement to see which columns have an explicit
`DEFAULT' clause.

Implicit defaults are defined as follows:

   * For numeric types, the default is `0', with the exception that for
     integer or floating-point types declared with the `AUTO_INCREMENT'
     attribute, the default is the next value in the sequence.

   * For date and time types other than *Note `TIMESTAMP': datetime,
     the default is the appropriate `zero' value for the type. For the
     first *Note `TIMESTAMP': datetime. column in a table, the default
     value is the current date and time. See *Note
     date-and-time-types::.

   * For string types other than *Note `ENUM': enum, the default value
     is the empty string. For *Note `ENUM': enum, the default is the
     first enumeration value.

`SERIAL DEFAULT VALUE' in the definition of an integer column is an
alias for `NOT NULL AUTO_INCREMENT UNIQUE'.


File: manual.info,  Node: numeric-types,  Next: date-and-time-types,  Prev: data-type-overview,  Up: data-types

10.2 Numeric Types
==================

MySQL supports all of the standard SQL numeric data types. These types
include the exact numeric data types (*Note `INTEGER': numeric-types,
*Note `SMALLINT': numeric-types, *Note `DECIMAL': numeric-types, and
*Note `NUMERIC': numeric-types.), as well as the approximate numeric
data types (*Note `FLOAT': numeric-types, *Note `REAL': numeric-types,
and *Note `DOUBLE PRECISION': numeric-types.). The keyword *Note `INT':
numeric-types. is a synonym for *Note `INTEGER': numeric-types, and the
keyword *Note `DEC': numeric-types. is a synonym for *Note `DECIMAL':
numeric-types. For numeric type storage requirements, see *Note
storage-requirements::.

The numeric types used for the results of calculations depends on the
operations being performed and the numeric types of the operands; for
more information, see *Note arithmetic-functions::.

The *Note `BIT': numeric-types. data type stores bit-field values and
is supported for `MyISAM', `MEMORY', `InnoDB', and `Falcon' tables.

As an extension to the SQL standard, MySQL also supports the integer
types *Note `TINYINT': numeric-types, *Note `MEDIUMINT': numeric-types,
and *Note `BIGINT': numeric-types. The following table shows the
required storage and range for each of the integer types.

*Type*      *Bytes*     *Minimum Value*           *Maximum Value*
                        *(Signed/Unsigned)*       *(Signed/Unsigned)*
*Note       1           `-128'                    `127'
`TINYINT':                                        
numeric-types.                                      
                        `0'                       `255'
*Note       2           `-32768'                  `32767'
`SMALLINT':                                       
numeric-types.                                      
                        `0'                       `65535'
*Note       3           `-8388608'                `8388607'
`MEDIUMINT':                                      
numeric-types.                                      
                        `0'                       `16777215'
*Note       4           `-2147483648'             `2147483647'
`INT':                                            
numeric-types.                                      
                        `0'                       `4294967295'
*Note       8           `-9223372036854775808'    `9223372036854775807'
`BIGINT':                                         
numeric-types.                                      
                        `0'                       `18446744073709551615'

Another extension is supported by MySQL for optionally specifying the
display width of integer data types in parentheses following the base
keyword for the type (for example, `INT(4)'). This optional display
width may be used by applications to display integer values having a
width less than the width specified for the column by left-padding them
with spaces. (That is, this width is present in the metadata returned
with result sets. Whether it is used or not is up to the application.)

The display width does _not_ constrain the range of values that can be
stored in the column, nor the number of digits that are displayed for
values having a width exceeding that specified for the column. For
example, a column specified as `SMALLINT(3)' has the usual *Note
`SMALLINT': numeric-types. range of `-32768' to `32767', and values
outside the range allowed by three characters are displayed using more
than three characters.

When used in conjunction with the optional extension attribute
`ZEROFILL', the default padding of spaces is replaced with zeros. For
example, for a column declared as `INT(5) ZEROFILL', a value of `4' is
retrieved as `00004'.  Note that if you store larger values than the
display width in an integer column, you may experience problems when
MySQL generates temporary tables for some complicated joins, because in
these cases MySQL assumes that the data fits into the original column
width.

*Note*:

The `ZEROFILL' attribute is ignored when a column is involved in
expressions or *Note `UNION': union. queries.

All integer types can have an optional (non-standard) attribute
`UNSIGNED'. Unsigned values can be used when you want to allow only
non-negative numbers in a column and you need a larger upper numeric
range for the column. For example, if an *Note `INT': numeric-types.
column is `UNSIGNED', the size of the column's range is the same but
its endpoints shift from `-2147483648' and `2147483647' up to `0' and
`4294967295'.

Floating-point and fixed-point types also can be `UNSIGNED'. As with
integer types, this attribute prevents negative values from being
stored in the column. However, unlike the integer types, the upper
range of column values remains the same.

If you specify `ZEROFILL' for a numeric column, MySQL automatically
adds the `UNSIGNED' attribute to the column.

Integer or floating-point data types can have the additional attribute
`AUTO_INCREMENT'. When you insert a value of `NULL' (recommended) or
`0' into an indexed `AUTO_INCREMENT' column, the column is set to the
next sequence value. Typically this is `VALUE+1', where VALUE is the
largest value for the column currently in the table. `AUTO_INCREMENT'
sequences begin with `1'.

For floating-point data types, MySQL uses four bytes for
single-precision values and eight bytes for double-precision values.

The *Note `FLOAT': numeric-types. and *Note `DOUBLE': numeric-types.
data types are used to represent approximate numeric data values. For
*Note `FLOAT': numeric-types, the SQL standard allows an optional
specification of the precision (but not the range of the exponent) in
bits following the keyword *Note `FLOAT': numeric-types. in
parentheses. MySQL also supports this optional precision specification,
but the precision value is used only to determine storage size. A
precision from 0 to 23 results in a four-byte single-precision *Note
`FLOAT': numeric-types. column. A precision from 24 to 53 results in an
eight-byte double-precision *Note `DOUBLE': numeric-types. column.

MySQL allows a non-standard syntax: `FLOAT(M,D)' or `REAL(M,D)' or
`DOUBLE PRECISION(M,D)'.  Here, ``(M,D)'' means than values can be
stored with up to M digits in total, of which D digits may be after the
decimal point. For example, a column defined as `FLOAT(7,4)' will look
like `-999.9999' when displayed. MySQL performs rounding when storing
values, so if you insert `999.00009' into a `FLOAT(7,4)' column, the
approximate result is `999.0001'.

MySQL treats *Note `DOUBLE': numeric-types. as a synonym for *Note
`DOUBLE PRECISION': numeric-types. (a non-standard extension). MySQL
also treats *Note `REAL': numeric-types. as a synonym for *Note `DOUBLE
PRECISION': numeric-types. (a non-standard variation), unless the
`REAL_AS_FLOAT' SQL mode is enabled.

For maximum portability, code requiring storage of approximate numeric
data values should use *Note `FLOAT': numeric-types. or *Note `DOUBLE
PRECISION': numeric-types. with no specification of precision or number
of digits.

The *Note `DECIMAL': numeric-types. and *Note `NUMERIC': numeric-types.
data types are used to store exact numeric data values. In MySQL, *Note
`NUMERIC': numeric-types. is implemented as *Note `DECIMAL':
numeric-types. These types are used to store values for which it is
important to preserve exact precision, for example with monetary data.

MySQL 6.0 stores *Note `DECIMAL': numeric-types. and *Note `NUMERIC':
numeric-types. values in binary format.  Before MySQL 5.0.3, they were
stored as strings. See *Note precision-math::.

When declaring a *Note `DECIMAL': numeric-types. or *Note `NUMERIC':
numeric-types. column, the precision and scale can be (and usually is)
specified; for example:

     salary DECIMAL(5,2)

In this example, `5' is the precision and `2' is the scale. The
precision represents the number of significant digits that are stored
for values, and the scale represents the number of digits that can be
stored following the decimal point. If the scale is 0, *Note `DECIMAL':
numeric-types. and *Note `NUMERIC': numeric-types. values contain no
decimal point or fractional part.

Standard SQL requires that the `salary' column be able to store any
value with five digits and two decimals. In this case, therefore, the
range of values that can be stored in the `salary' column is from
`-999.99' to `999.99'.

In standard SQL, the syntax `DECIMAL(M)' is equivalent to
`DECIMAL(M,0)'.  Similarly, the syntax *Note `DECIMAL': numeric-types.
is equivalent to `DECIMAL(M,0)', where the implementation is allowed to
decide the value of M. MySQL supports both of these variant forms of
the *Note `DECIMAL': numeric-types. and *Note `NUMERIC': numeric-types.
syntax. The default value of M is 10.

The maximum number of digits for *Note `DECIMAL': numeric-types. or
*Note `NUMERIC': numeric-types. is 65, but the actual range for a given
*Note `DECIMAL': numeric-types. or *Note `NUMERIC': numeric-types.
column can be constrained by the precision or scale for a given column.
When such a column is assigned a value with more digits following the
decimal point than are allowed by the specified scale, the value is
converted to that scale. (The precise behavior is operating
system-specific, but generally the effect is truncation to the
allowable number of digits.)

The *Note `BIT': numeric-types. data type is used to store bit-field
values. A type of `BIT(M)' allows for storage of M-bit values.  M can
range from 1 to 64.

To specify bit values, `b'VALUE'' notation can be used. VALUE is a
binary value written using zeros and ones. For example, `b'111'' and
`b'10000000'' represent 7 and 128, respectively. See *Note
bit-field-values::.

If you assign a value to a `BIT(M)' column that is less than M bits
long, the value is padded on the left with zeros. For example,
assigning a value of `b'101'' to a `BIT(6)' column is, in effect, the
same as assigning `b'000101''.

When asked to store a value in a numeric column that is outside the
data type's allowable range, MySQL's behavior depends on the SQL mode
in effect at the time. For example, if no restrictive modes are
enabled, MySQL clips the value to the appropriate endpoint of the range
and stores the resulting value instead.  However, if strict SQL mode is
enabled, MySQL rejects a value that is out of range with an error, and
the insert fails, in accordance with the SQL standard.

In non-strict mode, when an out-of-range value is assigned to an
integer column, MySQL stores the value representing the corresponding
endpoint of the column data type range. If you store 256 into a *Note
`TINYINT': numeric-types. or `TINYINT UNSIGNED' column, MySQL stores
127 or 255, respectively. When a floating-point or fixed-point column is
assigned a value that exceeds the range implied by the specified (or
default) precision and scale, MySQL stores the value representing the
corresponding endpoint of that range.

Subtraction between integer values, where one is of type `UNSIGNED',
produces an unsigned result by default. If the result would otherwise
have been negative, it becomes the maximum integer value. If the
`NO_UNSIGNED_SUBTRACTION' SQL mode is enabled, the result is negative.

     mysql> SET SQL_MODE = '';
     mysql> SELECT CAST(0 AS UNSIGNED) - 1;
     +-------------------------+
     | CAST(0 AS UNSIGNED) - 1 |
     +-------------------------+
     |    18446744073709551615 |
     +-------------------------+

     mysql> SET SQL_MODE = 'NO_UNSIGNED_SUBTRACTION';
     mysql> SELECT CAST(0 AS UNSIGNED) - 1;
     +-------------------------+
     | CAST(0 AS UNSIGNED) - 1 |
     +-------------------------+
     |                      -1 |
     +-------------------------+

If the result of such an operation is used to update an `UNSIGNED'
integer column, the result is clipped to the maximum value for the
column type, or clipped to 0 if `NO_UNSIGNED_SUBTRACTION' is enabled.
If strict SQL mode is enabled, an error occurs and the column remains
unchanged.

Conversions that occur due to clipping when MySQL is not operating in
strict mode are reported as warnings for *Note `ALTER TABLE':
alter-table, *Note `LOAD DATA INFILE': load-data, *Note `UPDATE':
update, and multiple-row *Note `INSERT': insert. statements.  When
MySQL is operating in strict mode, these statements fail, and some or
all of the values will not be inserted or changed, depending on whether
the table is a transactional table and other factors. For details, see
*Note server-sql-mode::.


File: manual.info,  Node: date-and-time-types,  Next: string-types,  Prev: numeric-types,  Up: data-types

10.3 Date and Time Types
========================

* Menu:

* datetime::                     The `DATETIME', `DATE', and `TIMESTAMP' Types
* time::                         The `TIME' Type
* year::                         The `YEAR' Type
* y2k-issues::                   Year 2000 Issues and Date Types

The date and time types for representing temporal values are *Note
`DATETIME': datetime, *Note `DATE': datetime, *Note `TIMESTAMP':
datetime, *Note `TIME': time, and *Note `YEAR': year. Each temporal
type has a range of legal values, as well as a `zero' value that may be
used when you specify an illegal value that MySQL cannot represent. The
*Note `TIMESTAMP': datetime. type has special automatic updating
behavior, described later on. For temporal type storage requirements,
see *Note storage-requirements::.

MySQL gives warnings or errors if you try to insert an illegal date. By
setting the SQL mode to the appropriate value, you can specify more
exactly what kind of dates you want MySQL to support.  (See *Note
server-sql-mode::.) You can get MySQL to accept certain dates, such as
`'2009-11-31'', by using the `ALLOW_INVALID_DATES' SQL mode. This is
useful when you want to store a `possibly wrong' value which the user
has specified (for example, in a web form) in the database for future
processing. Under this mode, MySQL verifies only that the month is in
the range from 0 to 12 and that the day is in the range from 0 to 31.
These ranges are defined to include zero because MySQL allows you to
store dates where the day or month and day are zero in a *Note `DATE':
datetime. or *Note `DATETIME': datetime. column. This is extremely
useful for applications that need to store a birthdate for which you do
not know the exact date. In this case, you simply store the date as
`'2009-00-00'' or `'2009-01-00''. If you store dates such as these, you
should not expect to get correct results for functions such as
`DATE_SUB()' or `DATE_ADD()' that require complete dates. (If you do
_not_ want to allow zero in dates, you can use the `NO_ZERO_IN_DATE'
SQL mode).

A *Note `DATE': datetime. value is coerced to the *Note `DATETIME':
datetime. type by adding the time portion as `'00:00:00''. To perform
the comparison by ignoring the time part of the *Note `DATETIME':
datetime. value instead, use the `CAST()' function to perform the
comparison in the following way:

     DATE_COL = CAST(NOW() as DATE);

MySQL also allows you to store `'0000-00-00'' as a `dummy date' (if you
are not using the `NO_ZERO_DATE' SQL mode). This is in some cases more
convenient (and uses less data and index space) than using `NULL'
values.

Here are some general considerations to keep in mind when working with
date and time types:

   * MySQL retrieves values for a given date or time type in a standard
     output format, but it attempts to interpret a variety of formats
     for input values that you supply (for example, when you specify a
     value to be assigned to or compared to a date or time type). Only
     the formats described in the following sections are supported. It
     is expected that you supply legal values. Unpredictable results
     may occur if you use values in other formats.

   * Dates containing two-digit year values are ambiguous because the
     century is unknown. MySQL interprets two-digit year values using
     the following rules:

        * Year values in the range `70-99' are converted to `1970-1999'.

        * Year values in the range `00-69' are converted to `2000-2069'.

   * Although MySQL tries to interpret values in several formats, dates
     always must be given in year-month-day order (for example,
     `'98-09-04''), rather than in the month-day-year or day-month-year
     orders commonly used elsewhere (for example, `'09-04-98'',
     `'04-09-98'').

   * MySQL automatically converts a date or time type value to a number
     if the value is used in a numeric context and vice versa.

   * By default, when MySQL encounters a value for a date or time type
     that is out of range or otherwise illegal for the type (as
     described at the beginning of this section), it converts the value
     to the `zero' value for that type. The exception is that
     out-of-range *Note `TIME': time. values are clipped to the
     appropriate endpoint of the *Note `TIME': time. range.

     The following table shows the format of the `zero' value for each
     type. Note that the use of these values produces warnings if the
     `NO_ZERO_DATE' SQL mode is enabled.

     *Data Type*          *`Zero' Value*
     *Note `DATETIME':    `'0000-00-00 00:00:00''
     datetime.            
     *Note `DATE':        `'0000-00-00''
     datetime.            
     *Note `TIMESTAMP':   `'0000-00-00 00:00:00''
     datetime.            
     *Note `TIME': time.  `'00:00:00''
     *Note `YEAR': year.  `0000'

   * The `zero' values are special, but you can store or refer to them
     explicitly using the values shown in the table. You can also do
     this using the values `'0'' or `0', which are easier to write.

   * `Zero' date or time values used through MyODBC are converted
     automatically to `NULL' in MyODBC 2.50.12 and above, because ODBC
     cannot handle such values.


File: manual.info,  Node: datetime,  Next: time,  Prev: date-and-time-types,  Up: date-and-time-types

10.3.1 The `DATETIME', `DATE', and `TIMESTAMP' Types
----------------------------------------------------

* Menu:

* timestamp::                    `TIMESTAMP' Properties

The *Note `DATETIME': datetime, *Note `DATE': datetime, and *Note
`TIMESTAMP': datetime. types are related. This section describes their
characteristics, how they are similar, and how they differ.

The *Note `DATETIME': datetime. type is used when you need values that
contain both date and time information.  MySQL retrieves and displays
*Note `DATETIME': datetime. values in `'YYYY-MM-DD HH:MM:SS'' format.
The supported range is `'1000-01-01 00:00:00'' to `'9999-12-31
23:59:59''.

The *Note `DATE': datetime. type is used when you need only a date
value, without a time part. MySQL retrieves and displays *Note `DATE':
datetime. values in `'YYYY-MM-DD'' format. The supported range is
`'1000-01-01'' to `'9999-12-31''.

For the *Note `DATETIME': datetime. and *Note `DATE': datetime. range
descriptions, `supported' means that although earlier values might
work, there is no guarantee.

The *Note `TIMESTAMP': datetime. data type has a range of `'1970-01-01
00:00:01'' UTC to `'2038-01-09 03:14:07'' UTC. It has varying
properties, depending on the MySQL version and the SQL mode the server
is running in. These properties are described later in this section.

You can specify *Note `DATETIME': datetime, *Note `DATE': datetime, and
*Note `TIMESTAMP': datetime. values using any of a common set of
formats:

   * As a string in either `'YYYY-MM-DD HH:MM:SS'' or `'YY-MM-DD
     HH:MM:SS'' format. A `relaxed' syntax is allowed: Any punctuation
     character may be used as the delimiter between date parts or time
     parts. For example, `'98-12-31 11:30:45'', `'98.12.31 11+30+45'',
     `'98/12/31 11*30*45'', and `'98@12@31 11^30^45'' are equivalent.

   * As a string in either `'YYYY-MM-DD'' or `'YY-MM-DD'' format. A
     `relaxed' syntax is allowed here, too. For example, `'98-12-31'',
     `'98.12.31'', `'98/12/31'', and `'98@12@31'' are equivalent.

   * As a string with no delimiters in either `'YYYYMMDDHHMMSS'' or
     `'YYMMDDHHMMSS'' format, provided that the string makes sense as a
     date. For example, `'20070523091528'' and `'070523091528'' are
     interpreted as `'2007-05-23 09:15:28'', but `'071122129015'' is
     illegal (it has a nonsensical minute part) and becomes `'0000-00-00
     00:00:00''.

   * As a string with no delimiters in either `'YYYYMMDD'' or `'YYMMDD''
     format, provided that the string makes sense as a date. For
     example, `'20070523'' and `'070523'' are interpreted as
     `'2007-05-23'', but `'071332'' is illegal (it has nonsensical
     month and day parts) and becomes `'0000-00-00''.

   * As a number in either `YYYYMMDDHHMMSS' or `YYMMDDHHMMSS' format,
     provided that the number makes sense as a date. For example,
     `19830905132800' and `830905132800' are interpreted as
     `'1983-09-05 13:28:00''.

   * As a number in either `YYYYMMDD' or `YYMMDD' format, provided that
     the number makes sense as a date. For example, `19830905' and
     `830905' are interpreted as `'1983-09-05''.

   * As the result of a function that returns a value that is
     acceptable in a *Note `DATETIME': datetime, *Note `DATE':
     datetime, or *Note `TIMESTAMP': datetime. context, such as `NOW()'
     or `CURRENT_DATE'.

A microseconds part is allowable in temporal values in some contexts,
such as in literal values, and in the arguments to or return values
from some temporal functions. Microseconds are specified as a trailing
`.uuuuuu' part in the value. Example:

     mysql> SELECT MICROSECOND('2010-12-10 14:12:09.019473');
     +-------------------------------------------+
     | MICROSECOND('2010-12-10 14:12:09.019473') |
     +-------------------------------------------+
     |                                     19473 |
     +-------------------------------------------+

However, microseconds cannot be stored into a column of any temporal
data type. Any microseconds part is discarded.

Conversion of *Note `TIME': time. or *Note `DATETIME': datetime. values
to numeric form (for example, by adding `+0') results in a double value
with a microseconds part of `.000000':

     mysql> SELECT CURTIME(), CURTIME()+0;
     +-----------+---------------+
     | CURTIME() | CURTIME()+0   |
     +-----------+---------------+
     | 10:41:36  | 104136.000000 |
     +-----------+---------------+
     mysql> SELECT NOW(), NOW()+0;
     +---------------------+-----------------------+
     | NOW()               | NOW()+0               |
     +---------------------+-----------------------+
     | 2007-11-30 10:41:47 | 20071130104147.000000 |
     +---------------------+-----------------------+

Illegal *Note `DATETIME': datetime, *Note `DATE': datetime, or *Note
`TIMESTAMP': datetime. values are converted to the `zero' value of the
appropriate type (`'0000-00-00 00:00:00'' or `'0000-00-00'').

For values specified as strings that include date part delimiters, it
is not necessary to specify two digits for month or day values that are
less than `10'.  `'1979-6-9'' is the same as `'1979-06-09''. Similarly,
for values specified as strings that include time part delimiters, it
is not necessary to specify two digits for hour, minute, or second
values that are less than `10'.  `'1979-10-30 1:2:3'' is the same as
`'1979-10-30 01:02:03''.

Values specified as numbers should be 6, 8, 12, or 14 digits long. If a
number is 8 or 14 digits long, it is assumed to be in `YYYYMMDD' or
`YYYYMMDDHHMMSS' format and that the year is given by the first 4
digits. If the number is 6 or 12 digits long, it is assumed to be in
`YYMMDD' or `YYMMDDHHMMSS' format and that the year is given by the
first 2 digits. Numbers that are not one of these lengths are
interpreted as though padded with leading zeros to the closest length.

Values specified as non-delimited strings are interpreted using their
length as given. If the string is 8 or 14 characters long, the year is
assumed to be given by the first 4 characters.  Otherwise, the year is
assumed to be given by the first 2 characters. The string is
interpreted from left to right to find year, month, day, hour, minute,
and second values, for as many parts as are present in the string. This
means you should not use strings that have fewer than 6 characters. For
example, if you specify `'9903'', thinking that represents March, 1999,
MySQL inserts a `zero' date value into your table. This occurs because
the year and month values are `99' and `03', but the day part is
completely missing, so the value is not a legal date.  However, you can
explicitly specify a value of zero to represent missing month or day
parts. For example, you can use `'990300'' to insert the value
`'1999-03-00''.

You can to some extent assign values of one date type to an object of a
different date type. However, there may be some alteration of the value
or loss of information:

   * If you assign a *Note `DATE': datetime. value to a *Note
     `DATETIME': datetime. or *Note `TIMESTAMP': datetime. object, the
     time part of the resulting value is set to `'00:00:00'' because the
     *Note `DATE': datetime. value contains no time information.

   * If you assign a *Note `DATETIME': datetime. or *Note `TIMESTAMP':
     datetime. value to a *Note `DATE': datetime. object, the time part
     of the resulting value is deleted because the *Note `DATE':
     datetime. type stores no time information.

   * Remember that although *Note `DATETIME': datetime, *Note `DATE':
     datetime, and *Note `TIMESTAMP': datetime. values all can be
     specified using the same set of formats, the types do not all have
     the same range of values. For example, *Note `TIMESTAMP':
     datetime. values cannot be earlier than `1970' UTC or later than
     `'2038-01-09 03:14:07'' UTC. This means that a date such as
     `'1968-01-01'', while legal as a *Note `DATETIME': datetime. or
     *Note `DATE': datetime. value, is not valid as a *Note
     `TIMESTAMP': datetime. value and is converted to `0'.

Be aware of certain problems when specifying date values:

   * The relaxed format allowed for values specified as strings can be
     deceiving. For example, a value such as `'10:11:12'' might look
     like a time value because of the ``:'' delimiter, but if used in a
     date context is interpreted as the year `'2010-11-12''. The value
     `'10:45:15'' is converted to `'0000-00-00'' because `'45'' is not
     a legal month.

   * The server requires that month and day values be legal, and not
     merely in the range 1 to 12 and 1 to 31, respectively.  With
     strict mode disabled, invalid dates such as `'2004-04-31'' are
     converted to `'0000-00-00'' and a warning is generated.  With
     strict mode enabled, invalid dates generate an error.  To allow
     such dates, enable `ALLOW_INVALID_DATES'. See *Note
     server-sql-mode::, for more information.

   * MySQL does not accept timestamp values that include a zero in the
     day or month column or values that are not a valid date. The sole
     exception to this rule is the special value `'0000-00-00
     00:00:00''.

   * Dates containing two-digit year values are ambiguous because the
     century is unknown. MySQL interprets two-digit year values using
     the following rules:

        * Year values in the range `00-69' are converted to `2000-2069'.

        * Year values in the range `70-99' are converted to `1970-1999'.


File: manual.info,  Node: timestamp,  Prev: datetime,  Up: datetime

10.3.1.1 `TIMESTAMP' Properties
...............................

*Note `TIMESTAMP': datetime. columns are displayed in the same format
as *Note `DATETIME': datetime.  columns. In other words, the display
width is fixed at 19 characters, and the format is `'YYYY-MM-DD
HH:MM:SS''.

*Note `TIMESTAMP': datetime. values are converted from the current time
zone to UTC for storage, and converted back from UTC to the current
time zone for retrieval. (This occurs only for the *Note `TIMESTAMP':
datetime.  data type, not for other types such as *Note `DATETIME':
datetime.) By default, the current time zone for each connection is the
server's time.  The time zone can be set on a per-connection basis, as
described in *Note time-zone-support::. As long as the time zone
setting remains constant, you get back the same value you store. If you
store a *Note `TIMESTAMP': datetime. value, and then change the time
zone and retrieve the value, the retrieved value is different from the
value you stored. This occurs because the same time zone was not used
for conversion in both directions. The current time zone is available
as the value of the `time_zone' system variable.

The *Note `TIMESTAMP': datetime. data type offers automatic
initialization and updating. You can choose whether to use these
properties and which column should have them:

   * For one *Note `TIMESTAMP': datetime. column in a table, you can
     assign the current timestamp as the default value and the
     auto-update value. It is possible to have the current timestamp be
     the default value for initializing the column, for the auto-update
     value, or both. It is not possible to have the current timestamp be
     the default value for one column and the auto-update value for
     another column.

   * Any single *Note `TIMESTAMP': datetime. column in a table can be
     used as the one that is initialized to the current date and time,
     or updated automatically. This need not be the first *Note
     `TIMESTAMP': datetime. column.

   * If a `DEFAULT' value is specified for the first *Note `TIMESTAMP':
     datetime. column in a table, it is not ignored. The default can be
     `CURRENT_TIMESTAMP' or a constant date and time value.

   * In a *Note `CREATE TABLE': create-table.  statement, the first
     *Note `TIMESTAMP': datetime. column can be declared in any of the
     following ways:

        * With both `DEFAULT CURRENT_TIMESTAMP' and `ON UPDATE
          CURRENT_TIMESTAMP' clauses, the column has the current
          timestamp for its default value, and is automatically updated.

        * With neither `DEFAULT' nor `ON UPDATE' clauses, it is the same
          as `DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP'.

        * With a `DEFAULT CURRENT_TIMESTAMP' clause and no `ON UPDATE'
          clause, the column has the current timestamp for its default
          value but is not automatically updated.

        * With no `DEFAULT' clause and with an `ON UPDATE
          CURRENT_TIMESTAMP' clause, the column has a default of 0 and
          is automatically updated.

        * With a constant `DEFAULT' value, the column has the given
          default and is not automatically initialized to the current
          timestamp. If the column also has an `ON UPDATE
          CURRENT_TIMESTAMP' clause, it is automatically updated;
          otherwise, it has a constant default and is not automatically
          updated.

     In other words, you can use the current timestamp for both the
     initial value and the auto-update value, or either one, or
     neither. (For example, you can specify `ON UPDATE' to enable
     auto-update without also having the column auto-initialized.) The
     following column definitions demonstrate each of the possibilities:

        * Auto-initialization and auto-update:

               ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP

        * Auto-initialization only:

               ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP

        * Auto-update only:

               ts TIMESTAMP DEFAULT 0 ON UPDATE CURRENT_TIMESTAMP

        * Neither:

               ts TIMESTAMP DEFAULT 0

   * To specify automatic default or updating for a *Note `TIMESTAMP':
     datetime. column other than the first one, you must suppress the
     automatic initialization and update behaviors for the first *Note
     `TIMESTAMP': datetime. column by explicitly assigning it a constant
     `DEFAULT' value (for example, `DEFAULT 0' or `DEFAULT '2003-01-01
     00:00:00''). Then, for the other *Note `TIMESTAMP': datetime.
     column, the rules are the same as for the first *Note `TIMESTAMP':
     datetime. column, except that if you omit both of the `DEFAULT'
     and `ON UPDATE' clauses, no automatic initialization or updating
     occurs.

     Example:

          CREATE TABLE t (
              ts1 TIMESTAMP DEFAULT 0,
              ts2 TIMESTAMP DEFAULT CURRENT_TIMESTAMP
                            ON UPDATE CURRENT_TIMESTAMP);

   * `CURRENT_TIMESTAMP' or any of its synonyms (`CURRENT_TIMESTAMP()',
     `NOW()', `LOCALTIME', `LOCALTIME()', `LOCALTIMESTAMP', or
     `LOCALTIMESTAMP()') can be used in the `DEFAULT' and `ON UPDATE'
     clauses. They all mean `the current timestamp.' (`UTC_TIMESTAMP'
     is not allowed. Its range of values does not align with those of
     the *Note `TIMESTAMP': datetime. column anyway unless the current
     time zone is `UTC'.)

   * The order of the `DEFAULT' and `ON UPDATE' attributes does not
     matter.  If both `DEFAULT' and `ON UPDATE' are specified for a
     *Note `TIMESTAMP': datetime. column, either can precede the other.
     For example, these statements are equivalent:

          CREATE TABLE t (ts TIMESTAMP);
          CREATE TABLE t (ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP
                                       ON UPDATE CURRENT_TIMESTAMP);
          CREATE TABLE t (ts TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
                                       DEFAULT CURRENT_TIMESTAMP);

*Note*:

The examples that use `DEFAULT 0' will not work if the `NO_ZERO_DATE'
SQL mode is enabled because that mode causes `zero' date values
(specified as `0', `'0000-00-00', or `'0000-00-00 00:00:00'') to be
rejected. Be aware that the `TRADITIONAL' SQL mode includes
`NO_ZERO_DATE'.

*Note `TIMESTAMP': datetime. columns are `NOT NULL' by default, cannot
contain `NULL' values, and assigning `NULL' assigns the current
timestamp.  However, a *Note `TIMESTAMP': datetime. column can be
allowed to contain `NULL' by declaring it with the `NULL' attribute. In
this case, the default value also becomes `NULL' unless overridden with
a `DEFAULT' clause that specifies a different default value. `DEFAULT
NULL' can be used to explicitly specify `NULL' as the default value.
(For a *Note `TIMESTAMP': datetime. column not declared with the `NULL'
attribute, `DEFAULT NULL' is illegal.) If a *Note `TIMESTAMP':
datetime. column allows `NULL' values, assigning `NULL' sets it to
`NULL', not to the current timestamp.

The following table contains several *Note `TIMESTAMP': datetime.
columns that allow `NULL' values:

     CREATE TABLE t
     (
       ts1 TIMESTAMP NULL DEFAULT NULL,
       ts2 TIMESTAMP NULL DEFAULT 0,
       ts3 TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP
     );

Note that a *Note `TIMESTAMP': datetime. column that allows `NULL'
values will _not_ take on the current timestamp except under one of the
following conditions:

   * Its default value is defined as `CURRENT_TIMESTAMP'

   * `NOW()' or `CURRENT_TIMESTAMP' is inserted into the column

In other words, a *Note `TIMESTAMP': datetime.  column defined as
`NULL' will auto-initialize only if it is created using a definition
such as the following:

     CREATE TABLE t (ts TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP);

Otherwise -- that is, if the *Note `TIMESTAMP': datetime. column is
defined to allow `NULL' values but not using `DEFAULT
CURRENT_TIMESTAMP', as shown here...

     CREATE TABLE t1 (ts TIMESTAMP NULL DEFAULT NULL);
     CREATE TABLE t2 (ts TIMESTAMP NULL DEFAULT '0000-00-00 00:00:00');

...then you must explicitly insert a value corresponding to the current
date and time. For example:

     INSERT INTO t1 VALUES (NOW());
     INSERT INTO t2 VALUES (CURRENT_TIMESTAMP);

*Note*:

The MySQL server can be run with the `MAXDB' SQL mode enabled.  When
the server runs with this mode enabled, *Note `TIMESTAMP': datetime. is
identical with *Note `DATETIME': datetime. That is, if this mode is
enabled at the time that a table is created, *Note `TIMESTAMP':
datetime. columns are created as *Note `DATETIME': datetime. columns.
As a result, such columns use *Note `DATETIME': datetime. display
format, have the same range of values, and there is no automatic
initialization or updating to the current date and time.

To enable `MAXDB' mode, set the server SQL mode to `MAXDB' at startup
using the `--sql-mode=MAXDB' server option or by setting the global
`sql_mode' variable at runtime:

     mysql> SET GLOBAL sql_mode=MAXDB;

A client can cause the server to run in `MAXDB' mode for its own
connection as follows:

     mysql> SET SESSION sql_mode=MAXDB;


File: manual.info,  Node: time,  Next: year,  Prev: datetime,  Up: date-and-time-types

10.3.2 The `TIME' Type
----------------------

MySQL retrieves and displays *Note `TIME': time.  values in
`'HH:MM:SS'' format (or `'HHH:MM:SS'' format for large hours values).
*Note `TIME': time. values may range from `'-838:59:59'' to
`'838:59:59''. The hours part may be so large because the *Note `TIME':
time. type can be used not only to represent a time of day (which must
be less than 24 hours), but also elapsed time or a time interval
between two events (which may be much greater than 24 hours, or even
negative).

You can specify *Note `TIME': time. values in a variety of formats:

   * As a string in `'D HH:MM:SS.fraction'' format. You can also use
     one of the following `relaxed' syntaxes: `'HH:MM:SS.fraction'',
     `'HH:MM:SS'', `'HH:MM'', `'D HH:MM:SS'', `'D HH:MM'', `'D HH'', or
     `'SS''. Here `D' represents days and can have a value from 0 to
     34. Note that MySQL does not store the fraction part.

   * As a string with no delimiters in `'HHMMSS'' format, provided that
     it makes sense as a time. For example, `'101112'' is understood as
     `'10:11:12'', but `'109712'' is illegal (it has a nonsensical
     minute part) and becomes `'00:00:00''.

   * As a number in `HHMMSS' format, provided that it makes sense as a
     time. For example, `101112' is understood as `'10:11:12''. The
     following alternative formats are also understood: `SS', `MMSS',
     `HHMMSS', `HHMMSS.fraction'. Note that MySQL does not store the
     fraction part.

   * As the result of a function that returns a value that is
     acceptable in a *Note `TIME': time. context, such as
     `CURRENT_TIME'.

A trailing `.uuuuuu' microseconds part of *Note `TIME': time. values is
allowed under the same conditions as for other temporal values, as
described in *Note datetime::. This includes the property that any
microseconds part is discarded from values stored into *Note `TIME':
time. columns.

For *Note `TIME': time. values specified as strings that include a time
part delimiter, it is not necessary to specify two digits for hours,
minutes, or seconds values that are less than `10'. `'8:3:2'' is the
same as `'08:03:02''.

Be careful about assigning abbreviated values to a *Note `TIME': time.
column. Without colons, MySQL interprets values using the assumption
that the two rightmost digits represent seconds. (MySQL interprets
*Note `TIME': time. values as elapsed time rather than as time of day.)
For example, you might think of `'1112'' and `1112' as meaning
`'11:12:00'' (12 minutes after 11 o'clock), but MySQL interprets them
as `'00:11:12'' (11 minutes, 12 seconds). Similarly, `'12'' and `12'
are interpreted as `'00:00:12''.  *Note `TIME': time. values with
colons, by contrast, are always treated as time of the day. That is,
`'11:12'' mean `'11:12:00'', not `'00:11:12''.

By default, values that lie outside the *Note `TIME': time. range but
are otherwise legal are clipped to the closest endpoint of the range.
For example, `'-850:00:00'' and `'850:00:00'' are converted to
`'-838:59:59'' and `'838:59:59''. Illegal *Note `TIME': time. values
are converted to `'00:00:00''. Note that because `'00:00:00'' is itself
a legal *Note `TIME': time. value, there is no way to tell, from a
value of `'00:00:00'' stored in a table, whether the original value was
specified as `'00:00:00'' or whether it was illegal.

For more restrictive treatment of invalid *Note `TIME': time. values,
enable strict SQL mode to cause errors to occur. See *Note
server-sql-mode::.


File: manual.info,  Node: year,  Next: y2k-issues,  Prev: time,  Up: date-and-time-types

10.3.3 The `YEAR' Type
----------------------

The *Note `YEAR': year. type is a one-byte type used for representing
years. It can be declared as `YEAR(2)' or `YEAR(4)' to specify a
display width of two or four characters. The default is four characters
if no width is given.

For four-digit format, MySQL displays *Note `YEAR': year. values in
`YYYY' format, with a range of `1901' to `2155'. For two-digit format,
MySQL displays values with a range of `70' (1970) to `69' (2069).

You can specify input *Note `YEAR': year. values in a variety of
formats:

   * As a four-digit string in the range `'1901'' to `'2155''.

   * As a four-digit number in the range `1901' to `2155'.

   * As a two-digit string in the range `'00'' to `'99''. Values in the
     ranges `'00'' to `'69'' and `'70'' to `'99'' are converted to
     *Note `YEAR': year. values in the ranges `2000' to `2069' and
     `1970' to `1999'.

   * As a two-digit number in the range `1' to `99'. Values in the
     ranges `1' to `69' and `70' to `99' are converted to *Note `YEAR':
     year. values in the ranges `2001' to `2069' and `1970' to `1999'.
     Note that the range for two-digit numbers is slightly different
     from the range for two-digit strings, because you cannot specify
     zero directly as a number and have it be interpreted as `2000'.
     You must specify it as a string `'0'' or `'00'' or it is
     interpreted as `0000'.

   * As the result of a function that returns a value that is
     acceptable in a *Note `YEAR': year. context, such as `NOW()'.

Illegal *Note `YEAR': year. values are converted to `0000'.


File: manual.info,  Node: y2k-issues,  Prev: year,  Up: date-and-time-types

10.3.4 Year 2000 Issues and Date Types
--------------------------------------

MySQL Server itself has no problems with Year 2000 (Y2K) compliance:

   * MySQL Server uses Unix time functions that handle dates into the
     year `2038' for *Note `TIMESTAMP': datetime. values. For *Note
     `DATE': datetime. and *Note `DATETIME': datetime. values, dates
     through the year `9999' are accepted.

   * All MySQL date functions are implemented in one source file,
     `sql/time.cc', and are coded very carefully to be year 2000-safe.

   * In MySQL, the *Note `YEAR': year. data type can store the years
     `0' and `1901' to `2155' in one byte and display them using two or
     four digits. All two-digit years are considered to be in the range
     `1970' to `2069', which means that if you store `01' in a *Note
     `YEAR': year. column, MySQL Server treats it as `2001'.

Although MySQL Server itself is Y2K-safe, you may run into problems if
you use it with applications that are not Y2K-safe.  For example, many
old applications store or manipulate years using two-digit values
(which are ambiguous) rather than four-digit values. This problem may
be compounded by applications that use values such as `00' or `99' as
`missing' value indicators. Unfortunately, these problems may be
difficult to fix because different applications may be written by
different programmers, each of whom may use a different set of
conventions and date-handling functions.

Thus, even though MySQL Server has no Y2K problems, _it is the
application's responsibility to provide unambiguous input_. Any value
containing a two-digit year is ambiguous, because the century is
unknown. Such values must be interpreted into four-digit form because
MySQL stores years internally using four digits.

For *Note `DATETIME': datetime, *Note `DATE': datetime, *Note
`TIMESTAMP': datetime, and *Note `YEAR': year. types, MySQL interprets
dates with ambiguous year values using the following rules:

   * Year values in the range `00-69' are converted to `2000-2069'.

   * Year values in the range `70-99' are converted to `1970-1999'.

Remember that these rules are only heuristics that provide reasonable
guesses as to what your data values mean. If the rules used by MySQL do
not produce the correct values, you should provide unambiguous input
containing four-digit year values.

`ORDER BY' properly sorts *Note `YEAR': year. values that have two-digit
years.

Some functions like `MIN()' and `MAX()' convert a *Note `YEAR': year.
to a number. This means that a value with a two-digit year does not
work properly with these functions. The fix in this case is to convert
the *Note `TIMESTAMP': datetime. or *Note `YEAR': year. to four-digit
year format.


File: manual.info,  Node: string-types,  Next: storage-requirements,  Prev: date-and-time-types,  Up: data-types

10.4 String Types
=================

* Menu:

* char::                         The `CHAR' and `VARCHAR' Types
* binary-varbinary::             The `BINARY' and `VARBINARY' Types
* blob::                         The `BLOB' and `TEXT' Types
* enum::                         The `ENUM' Type
* set::                          The `SET' Type

The string types are *Note `CHAR': char, *Note `VARCHAR': char, *Note
`BINARY': binary-varbinary, *Note `VARBINARY': binary-varbinary, *Note
`BLOB': blob, *Note `TEXT': blob, *Note `ENUM': enum, and *Note `SET':
set. This section describes how these types work and how to use them in
your queries. For string type storage requirements, see *Note
storage-requirements::.


File: manual.info,  Node: char,  Next: binary-varbinary,  Prev: string-types,  Up: string-types

10.4.1 The `CHAR' and `VARCHAR' Types
-------------------------------------

The *Note `CHAR': char. and *Note `VARCHAR': char. types are similar,
but differ in the way they are stored and retrieved. They also differ
in maximum length and in whether trailing spaces are retained.

The *Note `CHAR': char. and *Note `VARCHAR': char. types are declared
with a length that indicates the maximum number of characters you want
to store. For example, `CHAR(30)' can hold up to 30 characters.

The length of a *Note `CHAR': char. column is fixed to the length that
you declare when you create the table.  The length can be any value
from 0 to 255. When *Note `CHAR': char. values are stored, they are
right-padded with spaces to the specified length. When *Note `CHAR':
char. values are retrieved, trailing spaces are removed unless the
`PAD_CHAR_TO_FULL_LENGTH' SQL mode is enabled.

Values in *Note `VARCHAR': char. columns are variable-length strings.
The length can be specified as a value from 0 to 65,535. The effective
maximum length of a *Note `VARCHAR': char. is subject to the maximum
row size (65,535 bytes, which is shared among all columns) and the
character set used.

In contrast to *Note `CHAR': char, *Note `VARCHAR': char. values are
stored as a one-byte or two-byte length prefix plus data. The length
prefix indicates the number of bytes in the value. A column uses one
length byte if values require no more than 255 bytes, two length bytes
if values may require more than 255 bytes.

If strict SQL mode is not enabled and you assign a value to a *Note
`CHAR': char. or *Note `VARCHAR': char. column that exceeds the
column's maximum length, the value is truncated to fit and a warning is
generated. For truncation of non-space characters, you can cause an
error to occur (rather than a warning) and suppress insertion of the
value by using strict SQL mode. See *Note server-sql-mode::.

For *Note `VARCHAR': char. columns, trailing spaces in excess of the
column length are truncated prior to insertion and a warning is
generated, regardless of the SQL mode in use. For *Note `CHAR': char.
columns, truncation of excess trailing spaces from inserted values is
performed silently regardless of the SQL mode.

*Note `VARCHAR': char. values are not padded when they are stored.
Trailing spaces are retained when values are stored and retrieved, in
conformance with standard SQL.

The following table illustrates the differences between *Note `CHAR':
char. and *Note `VARCHAR': char. by showing the result of storing
various string values into `CHAR(4)' and `VARCHAR(4)' columns (assuming
that the column uses a single-byte character set such as `latin1').

*Value*     `CHAR(4)'   *Storage       `VARCHAR(4)'*Storage
                        Required*                  Required*
`'''        `'    ''    4 bytes        `'''        1 byte
`'ab''      `'ab  ''    4 bytes        `'ab''      3 bytes
`'abcd''    `'abcd''    4 bytes        `'abcd''    5 bytes
`'abcdefgh''`'abcd''    4 bytes        `'abcd''    5 bytes

The values shown as stored in the last row of the table apply _only
when not using strict mode_; if MySQL is running in strict mode, values
that exceed the column length are _not stored_, and an error results.

If a given value is stored into the `CHAR(4)' and `VARCHAR(4)' columns,
the values retrieved from the columns are not always the same because
trailing spaces are removed from *Note `CHAR': char. columns upon
retrieval. The following example illustrates this difference:

     mysql> CREATE TABLE vc (v VARCHAR(4), c CHAR(4));
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO vc VALUES ('ab  ', 'ab  ');
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT CONCAT('(', v, ')'), CONCAT('(', c, ')') FROM vc;
     +---------------------+---------------------+
     | CONCAT('(', v, ')') | CONCAT('(', c, ')') |
     +---------------------+---------------------+
     | (ab  )              | (ab)                |
     +---------------------+---------------------+
     1 row in set (0.06 sec)

Values in *Note `CHAR': char. and *Note `VARCHAR': char. columns are
sorted and compared according to the character set collation assigned to
the column.

All MySQL collations are of type `PADSPACE'.  This means that all *Note
`CHAR': char. and *Note `VARCHAR': char. values in MySQL are compared
without regard to any trailing spaces. For example:

     mysql> CREATE TABLE names (myname CHAR(10), yourname VARCHAR(10));
     Query OK, 0 rows affected (0.09 sec)

     mysql> INSERT INTO names VALUES ('Monty ', 'Monty ');
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT myname = 'Monty  ', yourname = 'Monty  ' FROM names;
     +--------------------+----------------------+
     | myname = 'Monty  ' | yourname = 'Monty  ' |
     +--------------------+----------------------+
     |                  1 |                    1 |
     +--------------------+----------------------+
     1 row in set (0.00 sec)

This is true for all MySQL versions, and that it is not affected by the
server SQL mode.

For those cases where trailing pad characters are stripped or
comparisons ignore them, if a column has an index that requires unique
values, inserting into the column values that differ only in number of
trailing pad characters will result in a duplicate-key error. For
example, if a table contains `'a'', an attempt to store `'a '' causes a
duplicate-key error.


File: manual.info,  Node: binary-varbinary,  Next: blob,  Prev: char,  Up: string-types

10.4.2 The `BINARY' and `VARBINARY' Types
-----------------------------------------

The *Note `BINARY': binary-varbinary. and *Note `VARBINARY':
binary-varbinary. types are similar to *Note `CHAR': char. and *Note
`VARCHAR': char, except that they contain binary strings rather than
non-binary strings. That is, they contain byte strings rather than
character strings. This means that they have no character set, and
sorting and comparison are based on the numeric values of the bytes in
the values.

The allowable maximum length is the same for *Note `BINARY':
binary-varbinary. and *Note `VARBINARY': binary-varbinary. as it is for
*Note `CHAR': char. and *Note `VARCHAR': char, except that the length
for *Note `BINARY': binary-varbinary. and *Note `VARBINARY':
binary-varbinary. is a length in bytes rather than in characters.

The *Note `BINARY': binary-varbinary. and *Note `VARBINARY':
binary-varbinary. data types are distinct from the `CHAR BINARY' and
`VARCHAR BINARY' data types. For the latter types, the `BINARY'
attribute does not cause the column to be treated as a binary string
column. Instead, it causes the binary collation for the column
character set to be used, and the column itself contains non-binary
character strings rather than binary byte strings. For example, `CHAR(5)
BINARY' is treated as `CHAR(5) CHARACTER SET latin1 COLLATE
latin1_bin', assuming that the default character set is `latin1'. This
differs from `BINARY(5)', which stores 5-bytes binary strings that have
no character set or collation. For information about differences
between non-binary string binary collations and binary strings, see
*Note charset-binary-collations::.

If strict SQL mode is not enabled and you assign a value to a *Note
`BINARY': binary-varbinary. or *Note `VARBINARY': binary-varbinary.
column that exceeds the column's maximum length, the value is truncated
to fit and a warning is generated. For cases of truncation, you can
cause an error to occur (rather than a warning) and suppress insertion
of the value by using strict SQL mode. See *Note server-sql-mode::.

When *Note `BINARY': binary-varbinary. values are stored, they are
right-padded with the pad value to the specified length. The pad value
is `0x00' (the zero byte). Values are right-padded with `0x00' on
insert, and no trailing bytes are removed on select. All bytes are
significant in comparisons, including `ORDER BY' and `DISTINCT'
operations.  `0x00' bytes and spaces are different in comparisons, with
`0x00' < space.

Example: For a `BINARY(3)' column, `'a '' becomes `'a \0'' when
inserted.  `'a\0'' becomes `'a\0\0'' when inserted. Both inserted
values remain unchanged when selected.

For *Note `VARBINARY': binary-varbinary, there is no padding on insert
and no bytes are stripped on select. All bytes are significant in
comparisons, including `ORDER BY' and `DISTINCT' operations.  `0x00'
bytes and spaces are different in comparisons, with `0x00' < space.

For those cases where trailing pad bytes are stripped or comparisons
ignore them, if a column has an index that requires unique values,
inserting into the column values that differ only in number of trailing
pad bytes will result in a duplicate-key error. For example, if a table
contains `'a'', an attempt to store `'a\0'' causes a duplicate-key
error.

You should consider the preceding padding and stripping characteristics
carefully if you plan to use the *Note `BINARY': binary-varbinary. data
type for storing binary data and you require that the value retrieved
be exactly the same as the value stored. The following example
illustrates how `0x00'-padding of *Note `BINARY': binary-varbinary.
values affects column value comparisons:

     mysql> CREATE TABLE t (c BINARY(3));
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO t SET c = 'a';
     Query OK, 1 row affected (0.01 sec)

     mysql> SELECT HEX(c), c = 'a', c = 'a\0\0' from t;
     +--------+---------+-------------+
     | HEX(c) | c = 'a' | c = 'a\0\0' |
     +--------+---------+-------------+
     | 610000 |       0 |           1 |
     +--------+---------+-------------+
     1 row in set (0.09 sec)

If the value retrieved must be the same as the value specified for
storage with no padding, it might be preferable to use *Note
`VARBINARY': binary-varbinary. or one of the *Note `BLOB': blob. data
types instead.


File: manual.info,  Node: blob,  Next: enum,  Prev: binary-varbinary,  Up: string-types

10.4.3 The `BLOB' and `TEXT' Types
----------------------------------

A *Note `BLOB': blob. is a binary large object that can hold a variable
amount of data. The four *Note `BLOB': blob. types are *Note
`TINYBLOB': blob, *Note `BLOB': blob, *Note `MEDIUMBLOB': blob, and
*Note `LONGBLOB': blob. These differ only in the maximum length of the
values they can hold. The four *Note `TEXT': blob. types are *Note
`TINYTEXT': blob, *Note `TEXT': blob, *Note `MEDIUMTEXT': blob, and
*Note `LONGTEXT': blob. These correspond to the four *Note `BLOB':
blob. types and have the same maximum lengths and storage requirements.
See *Note storage-requirements::.

*Note `BLOB': blob. columns are treated as binary strings (byte
strings).  *Note `TEXT': blob. columns are treated as non-binary
strings (character strings).  *Note `BLOB': blob. columns have no
character set, and sorting and comparison are based on the numeric
values of the bytes in column values.  *Note `TEXT': blob. columns have
a character set, and values are sorted and compared based on the
collation of the character set.

If strict SQL mode is not enabled and you assign a value to a *Note
`BLOB': blob. or *Note `TEXT': blob. column that exceeds the column's
maximum length, the value is truncated to fit and a warning is
generated. For truncation of non-space characters, you can cause an
error to occur (rather than a warning) and suppress insertion of the
value by using strict SQL mode. See *Note server-sql-mode::.

Beginning with MySQL 6.0.5, truncation of excess trailing spaces from
values to be inserted into *Note `TEXT': blob. columns always generates
a warning, regardless of the SQL mode. (Bug#30059
(http://bugs.mysql.com/30059))

If a *Note `TEXT': blob. column is indexed, index entry comparisons are
space-padded at the end. This means that, if the index requires unique
values, duplicate-key errors will occur for values that differ only in
the number of trailing spaces. For example, if a table contains `'a'',
an attempt to store `'a '' causes a duplicate-key error. This is not
true for *Note `BLOB': blob. columns.

In most respects, you can regard a *Note `BLOB': blob. column as a
*Note `VARBINARY': binary-varbinary. column that can be as large as you
like. Similarly, you can regard a *Note `TEXT': blob. column as a *Note
`VARCHAR': char. column.  *Note `BLOB': blob. and *Note `TEXT': blob.
differ from *Note `VARBINARY': binary-varbinary. and *Note `VARCHAR':
char. in the following ways:

   * For indexes on *Note `BLOB': blob. and *Note `TEXT': blob.
     columns, you must specify an index prefix length. For *Note
     `CHAR': char. and *Note `VARCHAR': char, a prefix length is
     optional. See *Note indexes::.

   * *Note `BLOB': blob. and *Note `TEXT': blob. columns cannot have
     `DEFAULT' values.

`LONG' and `LONG VARCHAR' map to the *Note `MEDIUMTEXT': blob. data
type. This is a compatibility feature. If you use the `BINARY'
attribute with a *Note `TEXT': blob. data type, the column is assigned
the binary collation of the column character set.

MySQL Connector/ODBC defines *Note `BLOB': blob.  values as
`LONGVARBINARY' and *Note `TEXT': blob. values as `LONGVARCHAR'.

Because *Note `BLOB': blob. and *Note `TEXT': blob. values can be
extremely long, you might encounter some constraints in using them:

   * Only the first `max_sort_length' bytes of the column are used when
     sorting. The default value of `max_sort_length' is 1024.  This
     value can be changed using the `--max_sort_length=N' option when
     starting the *Note `mysqld': mysqld. server.  See *Note
     server-system-variables::.

     You can make more bytes significant in sorting or grouping by
     increasing the value of `max_sort_length' at runtime.  Any client
     can change the value of its session `max_sort_length' variable:

          mysql> SET max_sort_length = 2000;
          mysql> SELECT id, comment FROM t
              -> ORDER BY comment;

     Another way to use `GROUP BY' or `ORDER BY' on a *Note `BLOB':
     blob. or *Note `TEXT': blob. column containing long values when
     you want more than `max_sort_length' bytes to be significant is to
     convert the column value into a fixed-length object. The standard
     way to do this is with the `SUBSTRING()' function. For example,
     the following statement causes 2000 bytes of the `comment' column
     to be taken into account for sorting:

          mysql> SELECT id, SUBSTRING(comment,1,2000) FROM t
              -> ORDER BY SUBSTRING(comment,1,2000);

   * The maximum size of a *Note `BLOB': blob. or *Note `TEXT': blob.
     object is determined by its type, but the largest value you
     actually can transmit between the client and server is determined
     by the amount of available memory and the size of the
     communications buffers.  You can change the message buffer size by
     changing the value of the `max_allowed_packet' variable, but you
     must do so for both the server and your client program. For
     example, both *Note `mysql': mysql.  and *Note `mysqldump':
     mysqldump. allow you to change the client-side
     `max_allowed_packet' value.  See *Note server-parameters::, *Note
     mysql::, and *Note mysqldump::.  You may also want to compare the
     packet sizes and the size of the data objects you are storing with
     the storage requirements, see *Note storage-requirements::

Each *Note `BLOB': blob. or *Note `TEXT': blob. value is represented
internally by a separately allocated object. This is in contrast to all
other data types, for which storage is allocated once per column when
the table is opened.

In some cases, it may be desirable to store binary data such as media
files in *Note `BLOB': blob. or *Note `TEXT': blob. columns. You may
find MySQL's string handling functions useful for working with such
data. See *Note string-functions::. For security and other reasons, it
is usually preferable to do so using application code rather than
allowing application users the `FILE' privilege. You can discuss
specifics for various languages and platforms in the MySQL Forums
(`http://forums.mysql.com/').


File: manual.info,  Node: enum,  Next: set,  Prev: blob,  Up: string-types

10.4.4 The `ENUM' Type
----------------------

An *Note `ENUM': enum. is a string object with a value chosen from a
list of allowed values that are enumerated explicitly in the column
specification at table creation time.

An enumeration value must be a quoted string literal; it may not be an
expression, even one that evaluates to a string value. For example, you
can create a table with an *Note `ENUM': enum. column like this:

     CREATE TABLE sizes (
         name ENUM('small', 'medium', 'large')
     );

However, this version of the previous *Note `CREATE TABLE':
create-table. statement does _not_ work:

     CREATE TABLE sizes (
         c1 ENUM('small', CONCAT('med','ium'), 'large')
     );

You also may not employ a user variable as an enumeration value.  This
pair of statements do _not_ work:

     SET @mysize = 'medium';

     CREATE TABLE sizes (
         name ENUM('small', @mysize, 'large')
     );

If you wish to use a number as an enumeration value, you must enclose
it in quotes.

Duplicate values in the definition cause a warning, or an error if
strict SQL mode is enabled.

The value may also be the empty string (`''') or `NULL' under certain
circumstances:

   * If you insert an invalid value into an *Note `ENUM': enum. (that
     is, a string not present in the list of allowed values), the empty
     string is inserted instead as a special error value. This string
     can be distinguished from a `normal' empty string by the fact that
     this string has the numerical value 0. More about this later.

     If strict SQL mode is enabled, attempts to insert invalid *Note
     `ENUM': enum. values result in an error.

   * If an *Note `ENUM': enum. column is declared to allow `NULL', the
     `NULL' value is a legal value for the column, and the default
     value is `NULL'. If an *Note `ENUM': enum. column is declared `NOT
     NULL', its default value is the first element of the list of
     allowed values.

Each enumeration value has an index:

   * Values from the list of allowable elements in the column
     specification are numbered beginning with 1.

   * The index value of the empty string error value is 0. This means
     that you can use the following *Note `SELECT': select. statement
     to find rows into which invalid *Note `ENUM': enum.  values were
     assigned:

          mysql> SELECT * FROM TBL_NAME WHERE ENUM_COL=0;

   * The index of the `NULL' value is `NULL'.

   * The term `index' here refers only to position within the list of
     enumeration values. It has nothing to do with table indexes.

For example, a column specified as `ENUM('one', 'two', 'three')' can
have any of the values shown here. The index of each value is also
shown.

*Value*     *Index*
`NULL'      `NULL'
`'''        0
`'one''     1
`'two''     2
`'three''   3

An enumeration can have a maximum of 65,535 elements.

Trailing spaces are automatically deleted from *Note `ENUM': enum.
member values in the table definition when a table is created.

When retrieved, values stored into an *Note `ENUM': enum. column are
displayed using the lettercase that was used in the column definition.
Note that *Note `ENUM': enum. columns can be assigned a character set
and collation. For binary or case-sensitive collations, lettercase is
taken into account when assigning values to the column.

If you retrieve an *Note `ENUM': enum. value in a numeric context, the
column value's index is returned. For example, you can retrieve numeric
values from an *Note `ENUM': enum. column like this:

     mysql> SELECT ENUM_COL+0 FROM TBL_NAME;

If you store a number into an *Note `ENUM': enum. column, the number is
treated as the index into the possible values, and the value stored is
the enumeration member with that index. (However, this does _not_ work
with *Note `LOAD DATA': load-data, which treats all input as strings.)
If the numeric value is quoted, it is still interpreted as an index if
there is no matching string in the list of enumeration values. For
these reasons, it is not advisable to define an *Note `ENUM': enum.
column with enumeration values that look like numbers, because this can
easily become confusing. For example, the following column has
enumeration members with string values of `'0'', `'1'', and `'2'', but
numeric index values of `1', `2', and `3':

     numbers ENUM('0','1','2')

If you store `2', it is interpreted as an index value, and becomes
`'1'' (the value with index 2). If you store `'2'', it matches an
enumeration value, so it is stored as `'2''. If you store `'3'', it
does not match any enumeration value, so it is treated as an index and
becomes `'2'' (the value with index 3).

     mysql> INSERT INTO t (numbers) VALUES(2),('2'),('3');
     mysql> SELECT * FROM t;
     +---------+
     | numbers |
     +---------+
     | 1       |
     | 2       |
     | 2       |
     +---------+

*Note `ENUM': enum. values are sorted according to the order in which
the enumeration members were listed in the column specification. (In
other words, *Note `ENUM': enum. values are sorted according to their
index numbers.) For example, `'a'' sorts before `'b'' for `ENUM('a',
'b')', but `'b'' sorts before `'a'' for `ENUM('b', 'a')'.  The empty
string sorts before non-empty strings, and `NULL' values sort before
all other enumeration values. To prevent unexpected results, specify the
*Note `ENUM': enum. list in alphabetical order.  You can also use
`GROUP BY CAST(col AS CHAR)' or `GROUP BY CONCAT(col)' to make sure
that the column is sorted lexically rather than by index number.

Functions such as `SUM()' or `AVG()' that expect a numeric argument
cast the argument to a number if necessary. For *Note `ENUM': enum.
values, the cast operation causes the index number to be used.

If you want to determine all possible values for an *Note `ENUM': enum.
column, use `SHOW COLUMNS FROM TBL_NAME LIKE ENUM_COL' and parse the
*Note `ENUM': enum. definition in the `Type' column of the output.


File: manual.info,  Node: set,  Prev: enum,  Up: string-types

10.4.5 The `SET' Type
---------------------

A *Note `SET': set. is a string object that can have zero or more
values, each of which must be chosen from a list of allowed values
specified when the table is created.  *Note `SET': set. column values
that consist of multiple set members are specified with members
separated by commas (``,''). A consequence of this is that *Note `SET':
set. member values should not themselves contain commas.

For example, a column specified as `SET('one', 'two') NOT NULL' can
have any of these values:

     ''
     'one'
     'two'
     'one,two'

A *Note `SET': set. can have a maximum of 64 different members.

Duplicate values in the definition cause a warning, or an error if
strict SQL mode is enabled.

Trailing spaces are automatically deleted from *Note `SET': set. member
values in the table definition when a table is created.

When retrieved, values stored in a *Note `SET': set. column are
displayed using the lettercase that was used in the column definition.
Note that *Note `SET': set. columns can be assigned a character set and
collation. For binary or case-sensitive collations, lettercase is taken
into account when assigning values to the column.

MySQL stores *Note `SET': set. values numerically, with the low-order
bit of the stored value corresponding to the first set member. If you
retrieve a *Note `SET': set. value in a numeric context, the value
retrieved has bits set corresponding to the set members that make up
the column value. For example, you can retrieve numeric values from a
*Note `SET': set. column like this:

     mysql> SELECT SET_COL+0 FROM TBL_NAME;

If a number is stored into a *Note `SET': set.  column, the bits that
are set in the binary representation of the number determine the set
members in the column value. For a column specified as
`SET('a','b','c','d')', the members have the following decimal and
binary values.

*Note       *Decimal       *Binary Value*
`SET': set. Value*         
*Member*                   
`'a''       `1'            `0001'
`'b''       `2'            `0010'
`'c''       `4'            `0100'
`'d''       `8'            `1000'

If you assign a value of `9' to this column, that is `1001' in binary,
so the first and fourth *Note `SET': set. value members `'a'' and `'d''
are selected and the resulting value is `'a,d''.

For a value containing more than one *Note `SET': set. element, it does
not matter what order the elements are listed in when you insert the
value.  It also does not matter how many times a given element is listed
in the value. When the value is retrieved later, each element in the
value appears once, with elements listed according to the order in
which they were specified at table creation time. For example, suppose
that a column is specified as `SET('a','b','c','d')':

     mysql> CREATE TABLE myset (col SET('a', 'b', 'c', 'd'));

If you insert the values `'a,d'', `'d,a'', `'a,d,d'', `'a,d,a'', and
`'d,a,d'':

     mysql> INSERT INTO myset (col) VALUES
     -> ('a,d'), ('d,a'), ('a,d,a'), ('a,d,d'), ('d,a,d');
     Query OK, 5 rows affected (0.01 sec)
     Records: 5  Duplicates: 0  Warnings: 0

Then all of these values appear as `'a,d'' when retrieved:

     mysql> SELECT col FROM myset;
     +------+
     | col  |
     +------+
     | a,d  |
     | a,d  |
     | a,d  |
     | a,d  |
     | a,d  |
     +------+
     5 rows in set (0.04 sec)

If you set a *Note `SET': set. column to an unsupported value, the
value is ignored and a warning is issued:

     mysql> INSERT INTO myset (col) VALUES ('a,d,d,s');
     Query OK, 1 row affected, 1 warning (0.03 sec)

     mysql> SHOW WARNINGS;
     +---------+------+------------------------------------------+
     | Level   | Code | Message                                  |
     +---------+------+------------------------------------------+
     | Warning | 1265 | Data truncated for column 'col' at row 1 |
     +---------+------+------------------------------------------+
     1 row in set (0.04 sec)

     mysql> SELECT col FROM myset;
     +------+
     | col  |
     +------+
     | a,d  |
     | a,d  |
     | a,d  |
     | a,d  |
     | a,d  |
     | a,d  |
     +------+
     6 rows in set (0.01 sec)

If strict SQL mode is enabled, attempts to insert invalid *Note `SET':
set. values result in an error.

*Note `SET': set. values are sorted numerically. `NULL' values sort
before non-`NULL' *Note `SET': set.  values.

Functions such as `SUM()' or `AVG()' that expect a numeric argument
cast the argument to a number if necessary. For *Note `SET': set.
values, the cast operation causes the numeric value to be used.

Normally, you search for *Note `SET': set.  values using the
`FIND_IN_SET()' function or the `LIKE' operator:

     mysql> SELECT * FROM TBL_NAME WHERE FIND_IN_SET('VALUE',SET_COL)>0;
     mysql> SELECT * FROM TBL_NAME WHERE SET_COL LIKE '%VALUE%';

The first statement finds rows where SET_COL contains the VALUE set
member. The second is similar, but not the same: It finds rows where
SET_COL contains VALUE anywhere, even as a substring of another set
member.

The following statements also are legal:

     mysql> SELECT * FROM TBL_NAME WHERE SET_COL & 1;
     mysql> SELECT * FROM TBL_NAME WHERE SET_COL = 'VAL1,VAL2';

The first of these statements looks for values containing the first set
member. The second looks for an exact match. Be careful with
comparisons of the second type. Comparing set values to `'VAL1,VAL2''
returns different results than comparing values to `'VAL2,VAL1''.  You
should specify the values in the same order they are listed in the
column definition.

If you want to determine all possible values for a *Note `SET': set.
column, use `SHOW COLUMNS FROM TBL_NAME LIKE SET_COL' and parse the
*Note `SET': set. definition in the `Type' column of the output.


File: manual.info,  Node: storage-requirements,  Next: choosing-types,  Prev: string-types,  Up: data-types

10.5 Data Type Storage Requirements
===================================

The storage requirements for each of the data types supported by MySQL
are listed here by category.

The maximum size of a row in a `MyISAM' table is 65,535 bytes.
(However, each *Note `BLOB': blob.  or *Note `TEXT': blob. column
contributes only 9-12 bytes toward this size.) This limitation may be
shared by other storage engines as well. See *Note storage-engines::,
for more information.

*Storage Requirements for Numeric Types*

*Data Type*                   *Storage Required*
*Note `TINYINT':              1 byte
numeric-types.                
*Note `SMALLINT':             2 bytes
numeric-types.                
*Note `MEDIUMINT':            3 bytes
numeric-types.                
*Note `INT': numeric-types,   4 bytes
*Note `INTEGER':              
numeric-types.                
*Note `BIGINT':               8 bytes
numeric-types.                
`FLOAT(P)'                    4 bytes if 0 <= P <= 24, 8 bytes if 25 <=
                              P <= 53
*Note `FLOAT': numeric-types. 4 bytes
`DOUBLE [PRECISION]', *Note   8 bytes
`REAL': numeric-types.        
`DECIMAL(M,D)',               Varies; see following discussion
`NUMERIC(M,D)'                
`BIT(M)'                      approximately (M+7)/8 bytes

Values for *Note `DECIMAL': numeric-types. (and *Note `NUMERIC':
numeric-types.) columns are represented using a binary format that
packs nine decimal (base 10) digits into four bytes. Storage for the
integer and fractional parts of each value are determined separately.
Each multiple of nine digits requires four bytes, and the `leftover'
digits require some fraction of four bytes. The storage required for
excess digits is given by the following table.

*Leftover Digits*  *Number of Bytes*
0                  0
1                  1
2                  1
3                  2
4                  2
5                  3
6                  3
7                  4
8                  4

*Storage Requirements for Date and Time Types*

*Data Type*                   *Storage Required*
*Note `DATE': datetime.       3 bytes
*Note `TIME': time.           3 bytes
*Note `DATETIME': datetime.   8 bytes
*Note `TIMESTAMP': datetime.  4 bytes
*Note `YEAR': year.           1 byte

The storage requirements shown in the table arise from the way that
MySQL represents temporal values:

   * *Note `DATE': datetime.: A three-byte integer packed as `DD' +
     `MM'x32 + `YYYY'x16x32

   * *Note `TIME': time.: A three-byte integer packed as `DD'x24x3600 +
     `HH'x3600 + `MM'x60 + `SS'

   * *Note `DATETIME': datetime.: Eight bytes:

        * A four-byte integer packed as `YYYY'x10000 + `MM'x100 + `DD'

        * A four-byte integer packed as `HH'x10000 + `MM'x100 + `SS'

   * *Note `TIMESTAMP': datetime.: A four-byte integer representing
     seconds UTC since the epoch (`'1970-01-01 00:00:00'' UTC)

   * *Note `YEAR': year.: A one-byte integer

*Storage Requirements for String Types*

In the following table, M represents the declared column length in
characters for non-binary string types and bytes for binary string
types.  L represents the actual length in bytes of a given string value.

*Data Type*                   *Storage Required*
`CHAR(M)'                     M x W bytes, 0 `<= M <=' 255, where W is
                              the number of bytes required for the
                              maximum-length character in the character
                              set
`BINARY(M)'                   M bytes, 0 `<= M <=' 255
`VARCHAR(M)', `VARBINARY(M)'  L + 1 bytes if column values require 0 -
                              255 bytes, L + 2 bytes if values may
                              require more than 255 bytes
*Note `TINYBLOB': blob,       L + 1 bytes, where L < 2^8
*Note `TINYTEXT': blob.       
*Note `BLOB': blob, *Note     L + 2 bytes, where L < 2^16
`TEXT': blob.                 
*Note `MEDIUMBLOB': blob,     L + 3 bytes, where L < 2^24
*Note `MEDIUMTEXT': blob.     
*Note `LONGBLOB': blob,       L + 4 bytes, where L < 2^32
*Note `LONGTEXT': blob.       
`ENUM('VALUE1','VALUE2',...)' 1 or 2 bytes, depending on the number of
                              enumeration values (65,535 values maximum)
`SET('VALUE1','VALUE2',...)'  1, 2, 3, 4, or 8 bytes, depending on the
                              number of set members (64 members maximum)

Variable-length string types are stored using a length prefix plus
data. The length prefix requires from one to four bytes depending on
the data type, and the value of the prefix is L (the byte length of the
string). For example, storage for a *Note `MEDIUMTEXT': blob.  value
requires L bytes to store the value plus three bytes to store the
length of the value.

To calculate the number of bytes used to store a particular *Note
`CHAR': char, *Note `VARCHAR': char, or *Note `TEXT': blob. column
value, you must take into account the character set used for that
column and whether the value contains multi-byte characters. In
particular, when using the `utf8' Unicode character set, you must keep
in mind that not all `utf8' characters use the same number of bytes and
can require up to four bytes per character. For a breakdown of the
storage used for different categories of `utf8' characters, see *Note
charset-unicode::.

*Note `VARCHAR': char, *Note `VARBINARY': binary-varbinary, and the
*Note `BLOB': blob. and *Note `TEXT': blob. types are variable-length
types. For each, the storage requirements depend on these factors:

   * The actual length of the column value

   * The column's maximum possible length

   * The character set used for the column, because some character sets
     contain multi-byte characters

For example, a `VARCHAR(255)' column can hold a string with a maximum
length of 255 characters. Assuming that the column uses the `latin1'
character set (one byte per character), the actual storage required is
the length of the string (L), plus one byte to record the length of the
string. For the string `'abcd'', L is 4 and the storage requirement is
five bytes. If the same column is instead declared to use the `ucs2'
double-byte character set, the storage requirement is 10 bytes: The
length of `'abcd'' is eight bytes and the column requires two bytes to
store lengths because the maximum length is greater than 255 (up to 510
bytes).

*Note*:

The effective maximum number of _bytes_ that can be stored in a *Note
`VARCHAR': char. or *Note `VARBINARY': binary-varbinary. column is
subject to the maximum row size of 65,535 bytes, which is shared among
all columns. For a *Note `VARCHAR': char. column that stores multi-byte
characters, the effective maximum number of _characters_ is less. For
example, `utf8' characters can require up to four bytes per character,
so a *Note `VARCHAR': char.  column that uses the `utf8' character set
can be declared to be a maximum of 16,383 characters.

The size of an *Note `ENUM': enum. object is determined by the number
of different enumeration values. One byte is used for enumerations with
up to 255 possible values. Two bytes are used for enumerations having
between 256 and 65,535 possible values. See *Note enum::.

The size of a *Note `SET': set. object is determined by the number of
different set members. If the set size is N, the object occupies
`(N+7)/8' bytes, rounded up to 1, 2, 3, 4, or 8 bytes. A *Note `SET':
set. can have a maximum of 64 members. See *Note set::.


File: manual.info,  Node: choosing-types,  Next: other-vendor-data-types,  Prev: storage-requirements,  Up: data-types

10.6 Choosing the Right Type for a Column
=========================================

For optimum storage, you should try to use the most precise type in all
cases. For example, if an integer column is used for values in the
range from `1' to `99999', `MEDIUMINT UNSIGNED' is the best type. Of
the types that represent all the required values, this type uses the
least amount of storage.

All basic calculations (`+', `-', `*', and `/') with *Note `DECIMAL':
numeric-types.  columns are done with precision of 65 decimal (base 10)
digits.  See *Note numeric-type-overview::.

If accuracy is not too important or if speed is the highest priority,
the *Note `DOUBLE': numeric-types. type may be good enough. For high
precision, you can always convert to a fixed-point type stored in a
*Note `BIGINT': numeric-types. This allows you to do all calculations
with 64-bit integers and then convert results back to floating-point
values as necessary.

`PROCEDURE ANALYSE' can be used to obtain suggestions for optimal
column data types. For more information, see *Note procedure-analyse::.


File: manual.info,  Node: other-vendor-data-types,  Prev: choosing-types,  Up: data-types

10.7 Using Data Types from Other Database Engines
=================================================

To facilitate the use of code written for SQL implementations from
other vendors, MySQL maps data types as shown in the following table.
These mappings make it easier to import table definitions from other
database systems into MySQL.

*Other Vendor Type*       *MySQL Type*
*Note `BOOL':             *Note `TINYINT': numeric-types.
numeric-types.            
*Note `BOOLEAN':          *Note `TINYINT': numeric-types.
numeric-types.            
`CHARACTER VARYING(M)'    `VARCHAR(M)'
*Note `FIXED':            *Note `DECIMAL': numeric-types.
numeric-types.            
*Note `FLOAT4':           *Note `FLOAT': numeric-types.
numeric-types.            
*Note `FLOAT8':           *Note `DOUBLE': numeric-types.
numeric-types.            
*Note `INT1':             *Note `TINYINT': numeric-types.
numeric-types.            
*Note `INT2':             *Note `SMALLINT': numeric-types.
numeric-types.            
*Note `INT3':             *Note `MEDIUMINT': numeric-types.
numeric-types.            
*Note `INT4':             *Note `INT': numeric-types.
numeric-types.            
`INT8'                    *Note `BIGINT': numeric-types.
`LONG VARBINARY'          *Note `MEDIUMBLOB': blob.
`LONG VARCHAR'            *Note `MEDIUMTEXT': blob.
`LONG'                    *Note `MEDIUMTEXT': blob.
*Note `MIDDLEINT':        *Note `MEDIUMINT': numeric-types.
numeric-types.            
*Note `NUMERIC':          *Note `DECIMAL': numeric-types.
numeric-types.            

Data type mapping occurs at table creation time, after which the
original type specifications are discarded. If you create a table with
types used by other vendors and then issue a `DESCRIBE TBL_NAME'
statement, MySQL reports the table structure using the equivalent MySQL
types. For example:

     mysql> CREATE TABLE t (a BOOL, b FLOAT8, c LONG VARCHAR, d NUMERIC);
     Query OK, 0 rows affected (0.00 sec)

     mysql> DESCRIBE t;
     +-------+---------------+------+-----+---------+-------+
     | Field | Type          | Null | Key | Default | Extra |
     +-------+---------------+------+-----+---------+-------+
     | a     | tinyint(1)    | YES  |     | NULL    |       |
     | b     | double        | YES  |     | NULL    |       |
     | c     | mediumtext    | YES  |     | NULL    |       |
     | d     | decimal(10,0) | YES  |     | NULL    |       |
     +-------+---------------+------+-----+---------+-------+
     4 rows in set (0.01 sec)


File: manual.info,  Node: functions,  Next: sql-syntax,  Prev: data-types,  Up: Top

11 Functions and Operators
**************************

* Menu:

* func-op-summary-ref::          Operator and Function Reference
* non-typed-operators::          Operators
* control-flow-functions::       Control Flow Functions
* string-functions::             String Functions
* numeric-functions::            Numeric Functions
* date-and-time-functions::      Date and Time Functions
* mysql-calendar::               What Calendar Is Used By MySQL?
* fulltext-search::              Full-Text Search Functions
* cast-functions::               Cast Functions and Operators
* xml-functions::                XML Functions
* other-functions::              Other Functions
* group-by-functions-and-modifiers::  Functions and Modifiers for Use with `GROUP BY' Clauses
* spatial-extensions::           Spatial Extensions
* precision-math::               Precision Math

Expressions can be used at several points in SQL statements, such as in
the `ORDER BY' or `HAVING' clauses of *Note `SELECT': select.
statements, in the `WHERE' clause of a *Note `SELECT': select, *Note
`DELETE': delete, or *Note `UPDATE': update. statement, or in *Note
`SET': set-option.  statements. Expressions can be written using
literal values, column values, `NULL', built-in functions, stored
functions, user-defined functions, and operators. This chapter
describes the functions and operators that are allowed for writing
expressions in MySQL. Instructions for writing stored functions and
user-defined functions are given in *Note stored-routines::, and *Note
adding-functions::. See *Note function-resolution::, for the rules
describing how the server interprets references to different kinds of
functions.

An expression that contains `NULL' always produces a `NULL' value
unless otherwise indicated in the documentation for a particular
function or operator.

*Note*:

By default, there must be no whitespace between a function name and the
parenthesis following it. This helps the MySQL parser distinguish
between function calls and references to tables or columns that happen
to have the same name as a function. However, spaces around function
arguments are permitted.

You can tell the MySQL server to accept spaces after function names by
starting it with the `--sql-mode=IGNORE_SPACE' option. (See *Note
server-sql-mode::.) Individual client programs can request this
behavior by using the `CLIENT_IGNORE_SPACE' option for *Note
`mysql_real_connect()': mysql-real-connect. In either case, all
function names become reserved words.

For the sake of brevity, most examples in this chapter display the
output from the *Note `mysql': mysql. program in abbreviated form.
Rather than showing examples in this format:

     mysql> SELECT MOD(29,9);
     +-----------+
     | mod(29,9) |
     +-----------+
     |         2 |
     +-----------+
     1 rows in set (0.00 sec)

This format is used instead:

     mysql> SELECT MOD(29,9);
             -> 2


File: manual.info,  Node: func-op-summary-ref,  Next: non-typed-operators,  Prev: functions,  Up: functions

11.1 Operator and Function Reference
====================================

*Note*:

This table is part of an ongoing process to expand and simplify the
information provided on these elements. Further improvements to the
table, and corresponding descriptions will be applied over the coming
months.

*Name*                        *Description*
`ABS()'                       Return the absolute value
`ACOS()'                      Return the arc cosine
`ADDDATE()'(v4.1.1)           Add dates
`ADDTIME()'(v4.1.1)           Add time
`AES_DECRYPT()'               Decrypt using AES
`AES_ENCRYPT()'               Encrypt using AES
`AND', `&&'                   Logical AND
`ASCII()'                     Return numeric value of left-most character
`ASIN()'                      Return the arc sine
`ATAN2()', `ATAN()'           Return the arc tangent of the two arguments
`ATAN()'                      Return the arc tangent
`AVG()'                       Return the average value of the argument
`BENCHMARK()'                 Repeatedly execute an expression
`BETWEEN ... AND ... '        Check whether a value is within a range of
                              values
`BIN()'                       Return a string representation of the
                              argument
`BINARY'                      Cast a string to a binary string
`BIT_AND()'                   Return bitwise and
`BIT_COUNT()'                 Return the number of bits that are set
`BIT_LENGTH()'                Return length of argument in bits
`BIT_OR()'                    Return bitwise or
`BIT_XOR()'(v4.1.1)           Return bitwise xor
`&'                           Bitwise AND
`~'                           Invert bits
`|'                           Bitwise OR
`^'                           Bitwise XOR
`CASE'                        Case operator
`CAST()'                      Cast a value as a certain type
`CEIL()'                      Return the smallest integer value not less
                              than  the argument
`CEILING()'                   Return the smallest integer value not less
                              than  the argument
`CHAR_LENGTH()'               Return number of characters in argument
`CHAR()'                      Return the character for each integer
                              passed
`CHARACTER_LENGTH()'          A synonym for CHAR_LENGTH()
`CHARSET()'(v4.1.0)           Return the character set of the argument
`COALESCE()'                  Return the first non-NULL argument
`COERCIBILITY()'(v4.1.1)      Return the collation coercibility value of
                              the string  argument
`COLLATION()'(v4.1.0)         Return the collation of the string argument
`COMPRESS()'(v4.1.1)          Return result as a binary string
`CONCAT_WS()'                 Return concatenate with  separator
`CONCAT()'                    Return concatenated string
`CONNECTION_ID()'             Return the connection ID (thread ID)   for
                              the connection
`CONV()'                      Convert numbers between different number
                              bases
`CONVERT_TZ()'(v4.1.3)        Convert from one timezone to another
`Convert()'                   Cast a value as a certain type
`COS()'                       Return the cosine
`COT()'                       Return the cotangent
`COUNT(DISTINCT)'             Return the count of a number of different
                              values
`COUNT()'                     Return a count of the number of rows
                              returned
`CRC32()'(v4.1.0)             Compute a cyclic redundancy check value
`CURDATE()'                   Return the current date
`CURRENT_DATE()',             Synonyms for CURDATE()
`CURRENT_DATE'                
`CURRENT_TIME()',             Synonyms for CURTIME()
`CURRENT_TIME'                
`CURRENT_TIMESTAMP()',        Synonyms for NOW()
`CURRENT_TIMESTAMP'           
`CURRENT_USER()',             Return the user name and host name
`CURRENT_USER'                combination
`CURTIME()'                   Return the current time
`DATABASE()'                  Return the default (current) database name
`DATE_ADD()'                  Add two dates
`DATE_FORMAT()'               Format date as specified
`DATE_SUB()'                  Subtract two dates
`DATE()'(v4.1.1)              Extract the date part of a date or
                              datetime expression
`DATEDIFF()'(v4.1.1)          Subtract two dates
`DAY()'(v4.1.1)               Synonym for DAYOFMONTH()
`DAYNAME()'(v4.1.21)          Return the name of the weekday
`DAYOFMONTH()'                Return the day of the month (0-31)
`DAYOFWEEK()'                 Return the weekday index of the argument
`DAYOFYEAR()'                 Return the day of the year (1-366)
`DECODE()'                    Decodes a string encrypted using ENCODE()
`DEFAULT()'                   Return the default value for a table column
`DEGREES()'                   Convert radians to degrees
`DES_DECRYPT()'               Decrypt a string
`DES_ENCRYPT()'               Encrypt a string
`DIV'(v4.1.0)                 Integer division
`/'                           Division operator
`ELT()'                       Return string at index number
`ENCODE()'                    Encode a string
`ENCRYPT()'                   Encrypt a string
`<=>'                         NULL-safe equal to operator
`='                           Equal operator
`EXP()'                       Raise to the power of
`EXPORT_SET()'                Return a string such that for every bit
                              set in the value  bits, you get an on
                              string and for every unset bit, you get an
                              off string
`EXTRACT'                     Extract part of a date
`ExtractValue()'(v5.1.5)      Extracts a value from an XML string using
                              XPath notation
`FIELD()'                     Return the index (position) of the first
                              argument  in the subsequent arguments
`FIND_IN_SET()'               Return the index position of  the first
                              argument within the second argument
`FLOOR()'                     Return the largest integer value not
                              greater than  the argument
`FORMAT()'                    Return a number formatted to specified
                              number of decimal places
`FOUND_ROWS()'                For a SELECT with a LIMIT clause, the
                              number of rows that would be returned were
                              there no LIMIT clause
`FROM_DAYS()'                 Convert a day number to a date
`FROM_UNIXTIME()'             Format UNIX timestamp as a date
`GET_FORMAT()'(v4.1.1)        Return a date format string
`GET_LOCK()'                  Get a named lock
`>='                          Greater than or equal operator
`>'                           Greater than operator
`GREATEST()'                  Return the largest argument
`GROUP_CONCAT()'(v4.1)        Return a concatenated string
`HEX()'                       Return a hexadecimal representation of a
                              decimal or string value
`HOUR()'                      Extract the hour
`IF()'                        If/else construct
`IFNULL()'                    Null if/else construct
`IN()'                        Check whether a value is within a set of
                              values
`INET_ATON()'                 Return the numeric value of an IP address
`INET_NTOA()'                 Return the IP address from a numeric value
`INSERT()'                    Insert a substring at the specified
                              position up to  the specified number of
                              characters
`INSTR()'                     Return the index of the first occurrence
                              of substring
`INTERVAL()'                  Return the index of the argument   that is
                              less than the first argument
`IS_FREE_LOCK()'              Checks whether the named lock  is free
`IS NOT NULL'                 NOT NULL value test
`IS NOT'                      Test a value against a boolean
`IS NULL'                     NULL value test
`IS_USED_LOCK()'(v4.1.0)      Checks whether the named lock is in use.
                              Return connection identifier if true.
`IS'                          Test a value against a boolean
`ISNULL()'                    Test whether the argument is NULL
`LAST_DAY'(v4.1.1)            Return the last day of the month for the
                              argument
`LAST_INSERT_ID()'            Value of the AUTOINCREMENT column   for
                              the last INSERT
`LCASE()'                     Synonym for LOWER()
`LEAST()'                     Return the smallest argument
`<<'                          Left shift
`LEFT()'                      Return the leftmost number of characters
                              as specified
`LENGTH()'                    Return the length of a string in bytes
`<='                          Less than or equal operator
`<'                           Less than operator
`LIKE'                        Simple pattern matching
`LN()'                        Return the natural logarithm of the
                              argument
`LOAD_FILE()'                 Load the named file
`LOCALTIME()', `LOCALTIME'    Synonym for NOW()
`LOCALTIMESTAMP',             Synonym for NOW()
`LOCALTIMESTAMP()'(v4.0.6)    
`LOCATE()'                    Return the position of the first
                              occurrence  of substring
`LOG10()'                     Return the base-10 logarithm of the
                              argument
`LOG2()'                      Return the base-2 logarithm of the argument
`LOG()'                       Return the natural logarithm of the first
                              argument
`LOWER()'                     Return the argument in lowercase
`LPAD()'                      Return the string argument, left-padded
                              with the specified string
`LTRIM()'                     Remove leading spaces
`MAKE_SET()'                  Return a set of comma-separated strings
                              that have the corresponding bit in bits set
`MAKEDATE()'(v4.1.1)          Create a date from the year and day of year
`MAKETIME'(v4.1.1)            MAKETIME()
`MASTER_POS_WAIT()'           Block until the slave has read and
                              applied all updates up to the specified
                              position
`MATCH'                       Perform full-text search
`MAX()'                       Return the maximum value
`MD5()'                       Calculate MD5 checksum
`MICROSECOND()'(v4.1.1)       Return the microseconds from argument
`MID()'                       Return a substring starting from the
                              specified position
`MIN()'                       Return the minimum value
`-'                           Minus operator
`MINUTE()'                    Return the minute from the argument
`MOD()'                       Return the remainder
`%'                           Modulo operator
`MONTH()'                     Return the month from the date passed
`MONTHNAME()'(v4.1.21)        Return the name of the month
`NAME_CONST()'(v5.0.12)       Causes the column to have the given name
`NOT BETWEEN ... AND ...'     Check whether a value is not within a
                              range of values
`!=', `<>'                    Not equal operator
`NOT IN()'                    Check whether a value is not within a set
                              of values
`NOT LIKE'                    Negation of simple pattern matching
`NOT REGEXP'                  Negation of REGEXP
`NOT', `!'                    Negates value
`NOW()'                       Return the current date and time
`NULLIF()'                    Return NULL if expr1 = expr2
`OCT()'                       Return an octal representation of a
                              decimal  number
`OCTET_LENGTH()'              A synonym for LENGTH()
`OLD_PASSWORD()'(v4.1)        Return the value of the  old (pre-4.1)
                              implementation of PASSWORD
`||', `OR'                    Logical OR
`ORD()'                       Return character code for leftmost
                              character of the  argument
`PASSWORD()'                  Calculate and return a password string
`PERIOD_ADD()'                Add a period to a year-month
`PERIOD_DIFF()'               Return the number of months between periods
`PI()'                        Return the value of pi
`+'                           Addition operator
`POSITION()'                  A synonym for LOCATE()
`POW()'                       Return the argument raised to the
                              specified power
`POWER()'                     Return the argument raised to the
                              specified power
*Note `PROCEDURE ANALYSE()':  Analyze the results of a query
procedure-analyse.            
`QUARTER()'                   Return the quarter from a date argument
`QUOTE()'                     Escape the argument for use in an SQL
                              statement
`RADIANS()'                   Return argument converted to radians
`RAND()'                      Return a random floating-point value
`REGEXP'                      Pattern matching using regular expressions
`RELEASE_LOCK()'              Releases the named lock
`REPEAT()'                    Repeat a string the specified number of
                              times
`REPLACE()'                   Replace occurrences of a specified string
`REVERSE()'                   Reverse the characters in a string
`>>'                          Right shift
`RIGHT()'                     Return the specified rightmost number of
                              characters
`RLIKE'                       Synonym for REGEXP
`ROUND()'                     Round the argument
`ROW_COUNT()'(v5.0.1)         The number of rows  updated
`RPAD()'                      Append string the specified number of times
`RTRIM()'                     Remove trailing spaces
`SCHEMA()'(v5.0.2)            A synonym for DATABASE()
`SEC_TO_TIME()'               Converts seconds to 'HH:MM:SS' format
`SECOND()'                    Return the second (0-59)
`SESSION_USER()'              Synonym for USER()
`SHA1()', `SHA()'             Calculate an SHA-1 160-bit checksum
`SHA2()'(v6.0.5)              Calculate an SHA-2 checksum
`SIGN()'                      Return the sign of the argument
`SIN()'                       Return the sine of the argument
`SLEEP()'(v5.0.12)            Sleep for a number of seconds
`SOUNDEX()'                   Return a soundex string
`SOUNDS LIKE'(v4.1.0)         Compare sounds
`SPACE()'                     Return a string of the specified number of
                              spaces
`SQRT()'                      Return the square root of the argument
`STD()'                       Return the population standard deviation
`STDDEV_POP()'(v5.0.3)        Return the population standard deviation
`STDDEV_SAMP()'(v5.0.3)       Return the sample standard deviation
`STDDEV()'                    Return the population standard deviation
`STR_TO_DATE()'(v4.1.1)       Convert a string to a date
`STRCMP()'                    Compare two strings
`SUBDATE()'                   A synonym for DATE_SUB() when invoked with
                              three arguments
`SUBSTR()'                    Return the substring as specified
`SUBSTRING_INDEX()'           Return a substring from a  string before
                              the specified number of occurrences of the
                              delimiter
`SUBSTRING()'                 Return the substring as specified
`SUBTIME()'(v4.1.1)           Subtract times
`SUM()'                       Return the sum
`SYSDATE()'                   Return the time at which the function
                              executes
`SYSTEM_USER()'               Synonym for USER()
`TAN()'                       Return the tangent of the argument
`TIME_FORMAT()'               Format as time
`TIME_TO_SEC()'               Return the argument converted to seconds
`TIME()'(v4.1.1)              Extract the time portion of the expression
                              passed
`TIMEDIFF()'(v4.1.1)          Subtract time
`*'                           Times operator
`TIMESTAMP()'(v4.1.1)         With a single argument, this function
                              returns the date or  datetime expression;
                              with two arguments, the sum of the
                              arguments
`TIMESTAMPADD()'(v5.0.0)      Add an interval to a datetime expression
`TIMESTAMPDIFF()'(v5.0.0)     Subtract an interval from a datetime
                              expression
`TO_DAYS()'                   Return the date argument converted to days
`TRIM()'                      Remove leading and trailing spaces
`TRUNCATE()'                  Truncate to specified number of decimal
                              places
`UCASE()'                     Synonym for UPPER()
`-'                           Change the sign of the argument
`UNCOMPRESS()'(v4.1.1)        Uncompress a string compressed
`UNCOMPRESSED_LENGTH()'(v4.1.1)Return the length of a string before
                              compression
`UNHEX()'(v4.1.2)             Convert each pair of hexadecimal digits
                              to a character
`UNIX_TIMESTAMP()'            Return a UNIX timestamp
`UpdateXML()'(v5.1.5)         Return replaced XML fragment
`UPPER()'                     Convert to uppercase
`USER()'                      Return the current user name and host name
`UTC_DATE()'(v4.1.1)          Return the current UTC date
`UTC_TIME()'(v4.1.1)          Return the current UTC time
`UTC_TIMESTAMP()'(v4.1.1)     Return the current UTC date and time
`UUID_SHORT()'(v5.1.20)       Return an integer-valued universal
                              identifier
`UUID()'(v4.1.2)              Return a Universal Unique Identifier (UUID)
`VALUES()'(v4.1.1)            Defines the values to be used during an
                              INSERT
`VAR_POP()'(v5.0.3)           Return the population standard variance
`VAR_SAMP()'(v5.0.3)          Return the sample variance
`VARIANCE()'(v4.1)            Return the population standard variance
`VERSION()'                   Returns a string that indicates the MySQL
                              server version
`WEEK()'                      Return the week number
`WEEKDAY()'                   Return the weekday index
`WEEKOFYEAR()'(v4.1.1)        Return the calendar week of the date (0-53)
`WEIGHT_STRING()'(v5.2.4)     Return the weight string for a string
`XOR'                         Logical XOR
`YEAR()'                      Return the year
`YEARWEEK()'                  Return the year and week


File: manual.info,  Node: non-typed-operators,  Next: control-flow-functions,  Prev: func-op-summary-ref,  Up: functions

11.2 Operators
==============

* Menu:

* operator-precedence::          Operator Precedence
* type-conversion::              Type Conversion in Expression Evaluation
* comparison-operators::         Comparison Functions and Operators
* logical-operators::            Logical Operators

*Name*                        *Description*
`AND', `&&'                   Logical AND
`BETWEEN ... AND ... '        Check whether a value is within a range of
                              values
`BINARY'                      Cast a string to a binary string
`&'                           Bitwise AND
`~'                           Invert bits
`|'                           Bitwise OR
`^'                           Bitwise XOR
`CASE'                        Case operator
`DIV'(v4.1.0)                 Integer division
`/'                           Division operator
`<=>'                         NULL-safe equal to operator
`='                           Equal operator
`>='                          Greater than or equal operator
`>'                           Greater than operator
`IS NOT NULL'                 NOT NULL value test
`IS NOT'                      Test a value against a boolean
`IS NULL'                     NULL value test
`IS'                          Test a value against a boolean
`<<'                          Left shift
`<='                          Less than or equal operator
`<'                           Less than operator
`LIKE'                        Simple pattern matching
`-'                           Minus operator
`%'                           Modulo operator
`NOT BETWEEN ... AND ...'     Check whether a value is not within a
                              range of values
`!=', `<>'                    Not equal operator
`NOT LIKE'                    Negation of simple pattern matching
`NOT REGEXP'                  Negation of REGEXP
`NOT', `!'                    Negates value
`||', `OR'                    Logical OR
`+'                           Addition operator
`REGEXP'                      Pattern matching using regular expressions
`>>'                          Right shift
`RLIKE'                       Synonym for REGEXP
`SOUNDS LIKE'(v4.1.0)         Compare sounds
`*'                           Times operator
`-'                           Change the sign of the argument
`XOR'                         Logical XOR


File: manual.info,  Node: operator-precedence,  Next: type-conversion,  Prev: non-typed-operators,  Up: non-typed-operators

11.2.1 Operator Precedence
--------------------------

Operator precedences are shown in the following list, from highest
precedence to the lowest. Operators that are shown together on a line
have the same precedence.

     INTERVAL
     BINARY, COLLATE
     !
     - (unary minus), ~ (unary bit inversion)
     ^
     *, /, DIV, %, MOD
     -, +
     <<, >>
     &
     |
     =, <=>, >=, >, <=, <, <>, !=, IS, LIKE, REGEXP, IN
     BETWEEN, CASE, WHEN, THEN, ELSE
     NOT
     &&, AND
     XOR
     ||, OR
     :=

The `||' operator has a precedence between `^' and the unary operators
if the `PIPES_AS_CONCAT' SQL mode is enabled.

*Note*:

If the `HIGH_NOT_PRECEDENCE' SQL mode is enabled, the precedence of
`NOT' is the same as that of the `!' operator. See *Note
server-sql-mode::.

The precedence of operators determines the order of evaluation of terms
in an expression. To override this order and group terms explicitly,
use parentheses. For example:

     mysql> SELECT 1+2*3;
             -> 7
     mysql> SELECT (1+2)*3;
             -> 9


File: manual.info,  Node: type-conversion,  Next: comparison-operators,  Prev: operator-precedence,  Up: non-typed-operators

11.2.2 Type Conversion in Expression Evaluation
-----------------------------------------------

When an operator is used with operands of different types, type
conversion occurs to make the operands compatible. Some conversions
occur implicitly. For example, MySQL automatically converts numbers to
strings as necessary, and vice versa.

     mysql> SELECT 1+'1';
             -> 2
     mysql> SELECT CONCAT(2,' test');
             -> '2 test'

It is also possible to perform explicit conversions. If you want to
convert a number to a string explicitly, use the `CAST()' or `CONCAT()'
function (`CAST()' is preferable):

     mysql> SELECT 38.8, CAST(38.8 AS CHAR);
             -> 38.8, '38.8'
     mysql> SELECT 38.8, CONCAT(38.8);
             -> 38.8, '38.8'

The following rules describe how conversion occurs for comparison
operations:

   * If one or both arguments are `NULL', the result of the comparison
     is `NULL', except for the `NULL'-safe `<=>' equality comparison
     operator. For `NULL <=> NULL', the result is true.

   * If both arguments in a comparison operation are strings, they are
     compared as strings.

   * If both arguments are integers, they are compared as integers.

   * Hexadecimal values are treated as binary strings if not compared
     to a number.

   * If one of the arguments is a *Note `TIMESTAMP': datetime. or *Note
     `DATETIME': datetime. column and the other argument is a constant,
     the constant is converted to a timestamp before the comparison is
     performed. This is done to be more ODBC-friendly. Note that this
     is not done for the arguments to `IN()'! To be safe, always use
     complete datetime, date, or time strings when doing comparisons.

   * In all other cases, the arguments are compared as floating-point
     (real) numbers.

The following examples illustrate conversion of strings to numbers for
comparison operations:

     mysql> SELECT 1 > '6x';
             -> 0
     mysql> SELECT 7 > '6x';
             -> 1
     mysql> SELECT 0 > 'x6';
             -> 0
     mysql> SELECT 0 = 'x6';
             -> 1

Note that when you are comparing a string column with a number, MySQL
cannot use an index on the column to look up the value quickly. If
STR_COL is an indexed string column, the index cannot be used when
performing the lookup in the following statement:

     SELECT * FROM TBL_NAME WHERE STR_COL=1;

The reason for this is that there are many different strings that may
convert to the value `1', such as `'1'', `' 1'', or `'1a''.

Comparisons that use floating-point numbers (or values that are
converted to floating-point numbers) are approximate because such
numbers are inexact. This might lead to results that appear
inconsistent:

     mysql> SELECT '18015376320243458' = 18015376320243458;
             -> 1
     mysql> SELECT '18015376320243459' = 18015376320243459;
             -> 0

Such results can occur because the values are converted to
floating-point numbers, which have only 53 bits of precision and are
subject to rounding:

     mysql> SELECT '18015376320243459'+0.0;
             -> 1.8015376320243e+16

Furthermore, the conversion from string to floating-point and from
integer to floating-point do not necessarily occur the same way. The
integer may be converted to floating-point by the CPU, whereas the
string is converted digit by digit in an operation that involves
floating-point multiplications.

The results shown will vary on different systems, and can be affected
by factors such as computer architecture or the compiler version or
optimization level. One way to avoid such problems is to use `CAST()'
so that a value will not be converted implicitly to a float-point
number:

     mysql> SELECT CAST('18015376320243459' AS UNSIGNED) = 18015376320243459;
             -> 1

For more information about floating-point comparisons, see *Note
problems-with-float::.

As of MySQL 6.0.5, the server includes `dtoa', a conversion library
that provides the basis for improved conversion between string or *Note
`DECIMAL': numeric-types. values and approximate-value (FLOAT/DOUBLE)
numbers:

   * Consistent conversion results across platforms, which eliminates,
     for example, Unix versus Windows conversion differences.

   * Accurate representation of values in cases where results
     previously did not provide sufficient precision, such as for
     values close to IEEE limits.

   * Conversion of numbers to string format with the best possible
     precision. The precision of `dtoa' is always the same or bettter
     than that of the standard C library functions.

Because the conversions produced by this library differ in some cases
from previous results, the potential exists for incompatibilities in
applications that rely on previous results.  For example, applications
that depend on a specific exact result from previous conversions might
need adjustment to accommodate additional precision.

The `dtoa' library provides conversions with the following properties. D
represents a value with a *Note `DECIMAL': numeric-types.  or string
representation, and F represents a floating-point number in native
binary (IEEE) format.

   * F -> D conversion is done with the best possible precision,
     returning D as the shortest string that yields F when read back in
     and rounded to the nearest value in native binary format as
     specified by IEEE.

   * D -> F conversion is done such that F is the nearest native binary
     number to the input decimal string D.

These properties imply that F -> D -> F conversions are lossless unless
F is `-inf', `+inf', or `NaN'. The latter values are not supported
because the SQL standard defines them as invalid values for *Note
`FLOAT': numeric-types. or *Note `DOUBLE': numeric-types.

For D -> F -> D conversions, a sufficient condition for losslessness is
that D uses 15 or fewer digits of precision, is not a denormal value,
`-inf', `+inf', or `NaN'. In some cases, the conversion is lossless
even if D has more than 15 digits of precision, but this is not always
the case.


File: manual.info,  Node: comparison-operators,  Next: logical-operators,  Prev: type-conversion,  Up: non-typed-operators

11.2.3 Comparison Functions and Operators
-----------------------------------------

*Name*                        *Description*
`BETWEEN ... AND ... '        Check whether a value is within a range of
                              values
`COALESCE()'                  Return the first non-NULL argument
`<=>'                         NULL-safe equal to operator
`='                           Equal operator
`>='                          Greater than or equal operator
`>'                           Greater than operator
`GREATEST()'                  Return the largest argument
`IN()'                        Check whether a value is within a set of
                              values
`INTERVAL()'                  Return the index of the argument   that is
                              less than the first argument
`IS NOT NULL'                 NOT NULL value test
`IS NOT'                      Test a value against a boolean
`IS NULL'                     NULL value test
`IS'                          Test a value against a boolean
`ISNULL()'                    Test whether the argument is NULL
`LEAST()'                     Return the smallest argument
`<='                          Less than or equal operator
`<'                           Less than operator
`LIKE'                        Simple pattern matching
`NOT BETWEEN ... AND ...'     Check whether a value is not within a
                              range of values
`!=', `<>'                    Not equal operator
`NOT IN()'                    Check whether a value is not within a set
                              of values
`NOT LIKE'                    Negation of simple pattern matching
`STRCMP()'                    Compare two strings

Comparison operations result in a value of `1' (`TRUE'), `0' (`FALSE'),
or `NULL'. These operations work for both numbers and strings. Strings
are automatically converted to numbers and numbers to strings as
necessary.

The following relational comparison operators can be used to compare
not only scalar operands, but row operands:

     =  >  <  >=  <=  <>  !=

For examples of row comparisons, see *Note row-subqueries::.

Some of the functions in this section return values other than `1'
(`TRUE'), `0' (`FALSE'), or `NULL'. For example, `LEAST()' and
`GREATEST()'. However, the value they return is based on comparison
operations performed according to the rules described in *Note
type-conversion::.

To convert a value to a specific type for comparison purposes, you can
use the `CAST()' function.  String values can be converted to a
different character set using `CONVERT()'. See *Note cast-functions::.

By default, string comparisons are not case sensitive and use the
current character set. The default is `latin1' (cp1252 West European),
which also works well for English.

   *  `='

     Equal:

          mysql> SELECT 1 = 0;
                  -> 0
          mysql> SELECT '0' = 0;
                  -> 1
          mysql> SELECT '0.0' = 0;
                  -> 1
          mysql> SELECT '0.01' = 0;
                  -> 0
          mysql> SELECT '.01' = 0.01;
                  -> 1

   *  `<=>'

     `NULL'-safe equal. This operator performs an equality comparison
     like the `=' operator, but returns `1' rather than `NULL' if both
     operands are `NULL', and `0' rather than `NULL' if one operand is
     `NULL'.

          mysql> SELECT 1 <=> 1, NULL <=> NULL, 1 <=> NULL;
                  -> 1, 1, 0
          mysql> SELECT 1 = 1, NULL = NULL, 1 = NULL;
                  -> 1, NULL, NULL

   *  `<>', `!='

     Not equal:

          mysql> SELECT '.01' <> '0.01';
                  -> 1
          mysql> SELECT .01 <> '0.01';
                  -> 0
          mysql> SELECT 'zapp' <> 'zappp';
                  -> 1

   *  `<='

     Less than or equal:

          mysql> SELECT 0.1 <= 2;
                  -> 1

   *  `<'

     Less than:

          mysql> SELECT 2 < 2;
                  -> 0

   *  `>='

     Greater than or equal:

          mysql> SELECT 2 >= 2;
                  -> 1

   *  `>'

     Greater than:

          mysql> SELECT 2 > 2;
                  -> 0

   *  `IS BOOLEAN_VALUE'

     Tests a value against a boolean value, where BOOLEAN_VALUE can be
     `TRUE', `FALSE', or `UNKNOWN'.

          mysql> SELECT 1 IS TRUE, 0 IS FALSE, NULL IS UNKNOWN;
                  -> 1, 1, 1

   *  `IS NOT BOOLEAN_VALUE'

     Tests a value against a boolean value, where BOOLEAN_VALUE can be
     `TRUE', `FALSE', or `UNKNOWN'.

          mysql> SELECT 1 IS NOT UNKNOWN, 0 IS NOT UNKNOWN, NULL IS NOT UNKNOWN;
                  -> 1, 1, 0

   *  `IS NULL'

     Tests whether a value is `NULL'.

          mysql> SELECT 1 IS NULL, 0 IS NULL, NULL IS NULL;
                  -> 0, 0, 1

     To work well with ODBC programs, MySQL supports the following
     extra features when using `IS NULL':

        * You can find the row that contains the most recent
          `AUTO_INCREMENT' value by issuing a statement of the
          following form immediately after generating the value:

               SELECT * FROM TBL_NAME WHERE AUTO_COL IS NULL

          This behavior can be disabled by setting `sql_auto_is_null =
          0'.  See *Note server-session-variables::.

        * For *Note `DATE': datetime. and *Note `DATETIME': datetime.
          columns that are declared as `NOT NULL', you can find the
          special date `'0000-00-00'' by using a statement like this:

               SELECT * FROM TBL_NAME WHERE DATE_COLUMN IS NULL

          This is needed to get some ODBC applications to work because
          ODBC does not support a `'0000-00-00'' date value.

   *  `IS NOT NULL'

     Tests whether a value is not `NULL'.

          mysql> SELECT 1 IS NOT NULL, 0 IS NOT NULL, NULL IS NOT NULL;
                  -> 1, 1, 0

   *  `EXPR BETWEEN MIN AND MAX'

     If EXPR is greater than or equal to MIN and EXPR is less than or
     equal to MAX, `BETWEEN' returns `1', otherwise it returns `0'.
     This is equivalent to the expression `(MIN <= EXPR AND EXPR <=
     MAX)' if all the arguments are of the same type. Otherwise type
     conversion takes place according to the rules described in *Note
     type-conversion::, but applied to all the three arguments.

          mysql> SELECT 1 BETWEEN 2 AND 3;
                  -> 0
          mysql> SELECT 'b' BETWEEN 'a' AND 'c';
                  -> 1
          mysql> SELECT 2 BETWEEN 2 AND '3';
                  -> 1
          mysql> SELECT 2 BETWEEN 2 AND 'x-3';
                  -> 0

     For best results when using `BETWEEN' with date or time values,
     you should use `CAST()' to explicitly convert the values to the
     desired data type.  Examples: If you compare a *Note `DATETIME':
     datetime. to two *Note `DATE': datetime. values, convert the *Note
     `DATE': datetime. values to *Note `DATETIME': datetime. values. If
     you use a string constant such as `'2001-1-1'' in a comparison to
     a *Note `DATE': datetime, cast the string to a *Note `DATE':
     datetime.

   *  `EXPR NOT BETWEEN MIN AND MAX'

     This is the same as `NOT (EXPR BETWEEN MIN AND MAX)'.

   *  `COALESCE(VALUE,...)'

     Returns the first non-`NULL' value in the list, or `NULL' if there
     are no non-`NULL' values.

          mysql> SELECT COALESCE(NULL,1);
                  -> 1
          mysql> SELECT COALESCE(NULL,NULL,NULL);
                  -> NULL

   *  `GREATEST(VALUE1,VALUE2,...)'

     With two or more arguments, returns the largest (maximum-valued)
     argument. The arguments are compared using the same rules as for
     `LEAST()'.

          mysql> SELECT GREATEST(2,0);
                  -> 2
          mysql> SELECT GREATEST(34.0,3.0,5.0,767.0);
                  -> 767.0
          mysql> SELECT GREATEST('B','A','C');
                  -> 'C'

     `GREATEST()' returns `NULL' if any argument is `NULL'.

   *  `EXPR IN (VALUE,...)'

     Returns `1' if EXPR is equal to any of the values in the `IN'
     list, else returns `0'. If all values are constants, they are
     evaluated according to the type of EXPR and sorted. The search for
     the item then is done using a binary search. This means `IN' is
     very quick if the `IN' value list consists entirely of constants.
     Otherwise, type conversion takes place according to the rules
     described in *Note type-conversion::, but applied to all the
     arguments.

          mysql> SELECT 2 IN (0,3,5,7);
                  -> 0
          mysql> SELECT 'wefwf' IN ('wee','wefwf','weg');
                  -> 1

     You should never mix quoted and unquoted values in an `IN' list
     because the comparison rules for quoted values (such as strings)
     and unquoted values (such as numbers) differ. Mixing types may
     therefore lead to inconsistent results. For example, do not write
     an `IN' expression like this:

          SELECT val1 FROM tbl1 WHERE val1 IN (1,2,'a');

     Instead, write it like this:

          SELECT val1 FROM tbl1 WHERE val1 IN ('1','2','a');

     The number of values in the `IN' list is only limited by the
     `max_allowed_packet' value.

     To comply with the SQL standard, `IN' returns `NULL' not only if
     the expression on the left hand side is `NULL', but also if no
     match is found in the list and one of the expressions in the list
     is `NULL'.

     `IN()' syntax can also be used to write certain types of
     subqueries. See *Note any-in-some-subqueries::.

   *  `EXPR NOT IN (VALUE,...)'

     This is the same as `NOT (EXPR IN (VALUE,...))'.

   *  `ISNULL(EXPR)'

     If EXPR is `NULL', `ISNULL()' returns `1', otherwise it returns
     `0'.

          mysql> SELECT ISNULL(1+1);
                  -> 0
          mysql> SELECT ISNULL(1/0);
                  -> 1

     `ISNULL()' can be used instead of `=' to test whether a value is
     `NULL'. (Comparing a value to `NULL' using `=' always yields
     false.)

     The `ISNULL()' function shares some special behaviors with the `IS
     NULL' comparison operator. See the description of `IS NULL'.

   *  `INTERVAL(N,N1,N2,N3,...)'

     Returns `0' if N < N1, `1' if N < N2 and so on or `-1' if N is
     `NULL'. All arguments are treated as integers. It is required that
     N1 < N2 < N3 < `...' < NN for this function to work correctly.
     This is because a binary search is used (very fast).

          mysql> SELECT INTERVAL(23, 1, 15, 17, 30, 44, 200);
                  -> 3
          mysql> SELECT INTERVAL(10, 1, 10, 100, 1000);
                  -> 2
          mysql> SELECT INTERVAL(22, 23, 30, 44, 200);
                  -> 0

   *  `LEAST(VALUE1,VALUE2,...)'

     With two or more arguments, returns the smallest (minimum-valued)
     argument. The arguments are compared using the following rules:

        * If the return value is used in an *Note `INTEGER':
          numeric-types. context or all arguments are integer-valued,
          they are compared as integers.

        * If the return value is used in a *Note `REAL': numeric-types.
          context or all arguments are real-valued, they are compared
          as reals.

        * If any argument is a case-sensitive string, the arguments are
          compared as case-sensitive strings.

        * In all other cases, the arguments are compared as
          case-insensitive strings.

     `LEAST()' returns `NULL' if any argument is `NULL'.

          mysql> SELECT LEAST(2,0);
                  -> 0
          mysql> SELECT LEAST(34.0,3.0,5.0,767.0);
                  -> 3.0
          mysql> SELECT LEAST('B','A','C');
                  -> 'A'

     Note that the preceding conversion rules can produce strange
     results in some borderline cases:

          mysql> SELECT CAST(LEAST(3600, 9223372036854775808.0) as SIGNED);
                  -> -9223372036854775808

     This happens because MySQL reads `9223372036854775808.0' in an
     integer context. The integer representation is not good enough to
     hold the value, so it wraps to a signed integer.


File: manual.info,  Node: logical-operators,  Prev: comparison-operators,  Up: non-typed-operators

11.2.4 Logical Operators
------------------------

*Name*                        *Description*
`AND', `&&'                   Logical AND
`NOT', `!'                    Negates value
`||', `OR'                    Logical OR
`XOR'                         Logical XOR

In SQL, all logical operators evaluate to `TRUE', `FALSE', or `NULL'
(`UNKNOWN'). In MySQL, these are implemented as 1 (`TRUE'), 0
(`FALSE'), and `NULL'. Most of this is common to different SQL database
servers, although some servers may return any non-zero value for `TRUE'.

Note that MySQL evaluates any non-zero or non-`NULL' value to `TRUE'.
For example, the following statements all assess to `TRUE':

     mysql> SELECT 10 IS TRUE;
     -> 1
     mysql> SELECT -10 IS TRUE;
     -> 1
     mysql> SELECT 'string' IS NOT NULL;
     -> 1

   *  `NOT', `!'

     Logical NOT. Evaluates to `1' if the operand is `0', to `0' if the
     operand is non-zero, and `NOT NULL' returns `NULL'.

          mysql> SELECT NOT 10;
                  -> 0
          mysql> SELECT NOT 0;
                  -> 1
          mysql> SELECT NOT NULL;
                  -> NULL
          mysql> SELECT ! (1+1);
                  -> 0
          mysql> SELECT ! 1+1;
                  -> 1

     The last example produces `1' because the expression evaluates the
     same way as `(!1)+1'.

   *  `AND', `&&'

     Logical AND. Evaluates to `1' if all operands are non-zero and not
     `NULL', to `0' if one or more operands are `0', otherwise `NULL' is
     returned.

          mysql> SELECT 1 && 1;
                  -> 1
          mysql> SELECT 1 && 0;
                  -> 0
          mysql> SELECT 1 && NULL;
                  -> NULL
          mysql> SELECT 0 && NULL;
                  -> 0
          mysql> SELECT NULL && 0;
                  -> 0

   *  `OR', `||'

     Logical OR. When both operands are non-`NULL', the result is `1'
     if any operand is non-zero, and `0' otherwise. With a `NULL'
     operand, the result is `1' if the other operand is non-zero, and
     `NULL' otherwise. If both operands are `NULL', the result is
     `NULL'.

          mysql> SELECT 1 || 1;
                  -> 1
          mysql> SELECT 1 || 0;
                  -> 1
          mysql> SELECT 0 || 0;
                  -> 0
          mysql> SELECT 0 || NULL;
                  -> NULL
          mysql> SELECT 1 || NULL;
                  -> 1

   *  `XOR'

     Logical XOR. Returns `NULL' if either operand is `NULL'. For
     non-`NULL' operands, evaluates to `1' if an odd number of operands
     is non-zero, otherwise `0' is returned.

          mysql> SELECT 1 XOR 1;
                  -> 0
          mysql> SELECT 1 XOR 0;
                  -> 1
          mysql> SELECT 1 XOR NULL;
                  -> NULL
          mysql> SELECT 1 XOR 1 XOR 1;
                  -> 1

     `a XOR b' is mathematically equal to `(a AND (NOT b)) OR ((NOT a)
     and b)'.


File: manual.info,  Node: control-flow-functions,  Next: string-functions,  Prev: non-typed-operators,  Up: functions

11.3 Control Flow Functions
===========================

*Name*                        *Description*
`CASE'                        Case operator
`IF()'                        If/else construct
`IFNULL()'                    Null if/else construct
`NULLIF()'                    Return NULL if expr1 = expr2

   *  `CASE VALUE WHEN [COMPARE_VALUE] THEN RESULT [WHEN
     [COMPARE_VALUE] THEN RESULT ...] [ELSE RESULT] END'

     `CASE WHEN [CONDITION] THEN RESULT [WHEN [CONDITION] THEN RESULT
     ...] [ELSE RESULT] END'

     The first version returns the RESULT where `VALUE=COMPARE_VALUE'.
     The second version returns the result for the first condition that
     is true. If there was no matching result value, the result after
     `ELSE' is returned, or `NULL' if there is no `ELSE' part.

          mysql> SELECT CASE 1 WHEN 1 THEN 'one'
              ->     WHEN 2 THEN 'two' ELSE 'more' END;
                  -> 'one'
          mysql> SELECT CASE WHEN 1>0 THEN 'true' ELSE 'false' END;
                  -> 'true'
          mysql> SELECT CASE BINARY 'B'
              ->     WHEN 'a' THEN 1 WHEN 'b' THEN 2 END;
                  -> NULL

     The default return type of a `CASE' expression is the compatible
     aggregated type of all return values, but also depends on the
     context in which it is used.  If used in a string context, the
     result is returned as a string. If used in a numeric context, then
     the result is returned as a decimal, real, or integer value.

     *Note*:

     The syntax of the `CASE' _expression_ shown here differs slightly
     from that of the SQL *Note `CASE': case-statement.  _statement_
     described in *Note case-statement::, for use inside stored
     programs. The *Note `CASE': case-statement.  statement cannot have
     an `ELSE NULL' clause, and it is terminated with `END CASE'
     instead of `END'.

   *  `IF(EXPR1,EXPR2,EXPR3)'

     If EXPR1 is `TRUE' (`EXPR1 <> 0' and `EXPR1 <> NULL') then `IF()'
     returns EXPR2; otherwise it returns EXPR3.  `IF()' returns a
     numeric or string value, depending on the context in which it is
     used.

          mysql> SELECT IF(1>2,2,3);
                  -> 3
          mysql> SELECT IF(1<2,'yes','no');
                  -> 'yes'
          mysql> SELECT IF(STRCMP('test','test1'),'no','yes');
                  -> 'no'

     If only one of EXPR2 or EXPR3 is explicitly `NULL', the result
     type of the `IF()' function is the type of the non-`NULL'
     expression.

     The default return type of `IF()' (which may matter when it is
     stored into a temporary table) is calculated as follows.

     *Expression*                       *Return
                                        Value*
     EXPR2 or EXPR3 returns a string    string
     EXPR2 or EXPR3 returns a           floating-point
     floating-point value               
     EXPR2 or EXPR3 returns an integer  integer

     If EXPR2 and EXPR3 are both strings, the result is case sensitive
     if either string is case sensitive.

     *Note*:

     There is also an *Note `IF': if-statement.  _statement_, which
     differs from the `IF()' _function_ described here. See *Note
     if-statement::.

   *  `IFNULL(EXPR1,EXPR2)'

     If EXPR1 is not `NULL', `IFNULL()' returns EXPR1; otherwise it
     returns EXPR2.  `IFNULL()' returns a numeric or string value,
     depending on the context in which it is used.

          mysql> SELECT IFNULL(1,0);
                  -> 1
          mysql> SELECT IFNULL(NULL,10);
                  -> 10
          mysql> SELECT IFNULL(1/0,10);
                  -> 10
          mysql> SELECT IFNULL(1/0,'yes');
                  -> 'yes'

     The default result value of `IFNULL(EXPR1,EXPR2)' is the more
     `general' of the two expressions, in the order `STRING', *Note
     `REAL': numeric-types, or *Note `INTEGER': numeric-types. Consider
     the case of a table based on expressions or where MySQL must
     internally store a value returned by `IFNULL()' in a temporary
     table:

          mysql> CREATE TABLE tmp SELECT IFNULL(1,'test') AS test;
          mysql> DESCRIBE tmp;
          +-------+--------------+------+-----+---------+-------+
          | Field | Type         | Null | Key | Default | Extra |
          +-------+--------------+------+-----+---------+-------+
          | test  | varbinary(4) | NO   |     |         |       |
          +-------+--------------+------+-----+---------+-------+

     In this example, the type of the `test' column is `CHAR(4)'.

   *  `NULLIF(EXPR1,EXPR2)'

     Returns `NULL' if `EXPR1 = EXPR2' is true, otherwise returns
     EXPR1. This is the same as `CASE WHEN EXPR1 = EXPR2 THEN NULL ELSE
     EXPR1 END'.

          mysql> SELECT NULLIF(1,1);
                  -> NULL
          mysql> SELECT NULLIF(1,2);
                  -> 1

     Note that MySQL evaluates EXPR1 twice if the arguments are not
     equal.


File: manual.info,  Node: string-functions,  Next: numeric-functions,  Prev: control-flow-functions,  Up: functions

11.4 String Functions
=====================

* Menu:

* string-comparison-functions::  String Comparison Functions
* regexp::                       Regular Expressions

*Name*                        *Description*
`ASCII()'                     Return numeric value of left-most character
`BIN()'                       Return a string representation of the
                              argument
`BIT_LENGTH()'                Return length of argument in bits
`CHAR_LENGTH()'               Return number of characters in argument
`CHAR()'                      Return the character for each integer
                              passed
`CHARACTER_LENGTH()'          A synonym for CHAR_LENGTH()
`CONCAT_WS()'                 Return concatenate with  separator
`CONCAT()'                    Return concatenated string
`ELT()'                       Return string at index number
`EXPORT_SET()'                Return a string such that for every bit
                              set in the value  bits, you get an on
                              string and for every unset bit, you get an
                              off string
`FIELD()'                     Return the index (position) of the first
                              argument  in the subsequent arguments
`FIND_IN_SET()'               Return the index position of  the first
                              argument within the second argument
`FORMAT()'                    Return a number formatted to specified
                              number of decimal places
`HEX()'                       Return a hexadecimal representation of a
                              decimal or string value
`INSERT()'                    Insert a substring at the specified
                              position up to  the specified number of
                              characters
`INSTR()'                     Return the index of the first occurrence
                              of substring
`LCASE()'                     Synonym for LOWER()
`LEFT()'                      Return the leftmost number of characters
                              as specified
`LENGTH()'                    Return the length of a string in bytes
`LIKE'                        Simple pattern matching
`LOAD_FILE()'                 Load the named file
`LOCATE()'                    Return the position of the first
                              occurrence  of substring
`LOWER()'                     Return the argument in lowercase
`LPAD()'                      Return the string argument, left-padded
                              with the specified string
`LTRIM()'                     Remove leading spaces
`MAKE_SET()'                  Return a set of comma-separated strings
                              that have the corresponding bit in bits set
`MATCH'                       Perform full-text search
`MID()'                       Return a substring starting from the
                              specified position
`NOT LIKE'                    Negation of simple pattern matching
`NOT REGEXP'                  Negation of REGEXP
`OCTET_LENGTH()'              A synonym for LENGTH()
`ORD()'                       Return character code for leftmost
                              character of the  argument
`POSITION()'                  A synonym for LOCATE()
`QUOTE()'                     Escape the argument for use in an SQL
                              statement
`REGEXP'                      Pattern matching using regular expressions
`REPEAT()'                    Repeat a string the specified number of
                              times
`REPLACE()'                   Replace occurrences of a specified string
`REVERSE()'                   Reverse the characters in a string
`RIGHT()'                     Return the specified rightmost number of
                              characters
`RLIKE'                       Synonym for REGEXP
`RPAD()'                      Append string the specified number of times
`RTRIM()'                     Remove trailing spaces
`SOUNDEX()'                   Return a soundex string
`SOUNDS LIKE'(v4.1.0)         Compare sounds
`SPACE()'                     Return a string of the specified number of
                              spaces
`STRCMP()'                    Compare two strings
`SUBSTR()'                    Return the substring as specified
`SUBSTRING_INDEX()'           Return a substring from a  string before
                              the specified number of occurrences of the
                              delimiter
`SUBSTRING()'                 Return the substring as specified
`TRIM()'                      Remove leading and trailing spaces
`UCASE()'                     Synonym for UPPER()
`UNHEX()'(v4.1.2)             Convert each pair of hexadecimal digits
                              to a character
`UPPER()'                     Convert to uppercase
`WEIGHT_STRING()'(v5.2.4)     Return the weight string for a string

String-valued functions return `NULL' if the length of the result would
be greater than the value of the `max_allowed_packet' system variable.
See *Note server-parameters::.

For functions that operate on string positions, the first position is
numbered 1.

For functions that take length arguments, non-integer arguments are
rounded to the nearest integer.

   *  `ASCII(STR)'

     Returns the numeric value of the leftmost character of the string
     STR. Returns `0' if STR is the empty string. Returns `NULL' if STR
     is `NULL'.  `ASCII()' works for 8-bit characters.

          mysql> SELECT ASCII('2');
                  -> 50
          mysql> SELECT ASCII(2);
                  -> 50
          mysql> SELECT ASCII('dx');
                  -> 100

     See also the `ORD()' function.

   *  `BIN(N)'

     Returns a string representation of the binary value of N, where N
     is a longlong (*Note `BIGINT': numeric-types.) number. This is
     equivalent to `CONV(N,10,2)'.  Returns `NULL' if N is `NULL'.

          mysql> SELECT BIN(12);
                  -> '1100'

   *  `BIT_LENGTH(STR)'

     Returns the length of the string STR in bits.

          mysql> SELECT BIT_LENGTH('text');
                  -> 32

   *  `CHAR(N,...  [USING CHARSET_NAME])'

     `CHAR()' interprets each argument N as an integer and returns a
     string consisting of the characters given by the code values of
     those integers. `NULL' values are skipped.

          mysql> SELECT CHAR(77,121,83,81,'76');
                  -> 'MySQL'
          mysql> SELECT CHAR(77,77.3,'77.3');
                  -> 'MMM'

     `CHAR()' arguments larger than 255 are converted into multiple
     result bytes. For example, `CHAR(256)' is equivalent to
     `CHAR(1,0)', and `CHAR(256*256)' is equivalent to `CHAR(1,0,0)':

          mysql> SELECT HEX(CHAR(1,0)), HEX(CHAR(256));
          +----------------+----------------+
          | HEX(CHAR(1,0)) | HEX(CHAR(256)) |
          +----------------+----------------+
          | 0100           | 0100           |
          +----------------+----------------+
          mysql> SELECT HEX(CHAR(1,0,0)), HEX(CHAR(256*256));
          +------------------+--------------------+
          | HEX(CHAR(1,0,0)) | HEX(CHAR(256*256)) |
          +------------------+--------------------+
          | 010000           | 010000             |
          +------------------+--------------------+

     By default, `CHAR()' returns a binary string. To produce a string
     in a given character set, use the optional `USING' clause:

          mysql> SELECT CHARSET(CHAR(0x65)), CHARSET(CHAR(0x65 USING utf8));
          +---------------------+--------------------------------+
          | CHARSET(CHAR(0x65)) | CHARSET(CHAR(0x65 USING utf8)) |
          +---------------------+--------------------------------+
          | binary              | utf8                           |
          +---------------------+--------------------------------+

     If `USING' is given and the result string is illegal for the given
     character set, a warning is issued.  Also, if strict SQL mode is
     enabled, the result from `CHAR()' becomes `NULL'.

   *  `CHAR_LENGTH(STR)'

     Returns the length of the string STR, measured in characters. A
     multi-byte character counts as a single character. This means that
     for a string containing five two-byte characters, `LENGTH()'
     returns `10', whereas `CHAR_LENGTH()' returns `5'.

   *  `CHARACTER_LENGTH(STR)'

     `CHARACTER_LENGTH()' is a synonym for `CHAR_LENGTH()'.

   *  `CONCAT(STR1,STR2,...)'

     Returns the string that results from concatenating the arguments.
     May have one or more arguments. If all arguments are non-binary
     strings, the result is a non-binary string. If the arguments
     include any binary strings, the result is a binary string. A
     numeric argument is converted to its equivalent binary string
     form; if you want to avoid that, you can use an explicit type
     cast, as in this example:

          SELECT CONCAT(CAST(INT_COL AS CHAR), CHAR_COL);

     `CONCAT()' returns `NULL' if any argument is `NULL'.

          mysql> SELECT CONCAT('My', 'S', 'QL');
                  -> 'MySQL'
          mysql> SELECT CONCAT('My', NULL, 'QL');
                  -> NULL
          mysql> SELECT CONCAT(14.3);
                  -> '14.3'

     For quoted strings, concatenation can be performed by placing the
     strings next to each other:

          mysql> SELECT 'My' 'S' 'QL';
                  -> 'MySQL'

   *  `CONCAT_WS(SEPARATOR,STR1,STR2,...)'

     `CONCAT_WS()' stands for Concatenate With Separator and is a
     special form of `CONCAT()'. The first argument is the separator
     for the rest of the arguments. The separator is added between the
     strings to be concatenated. The separator can be a string, as can
     the rest of the arguments. If the separator is `NULL', the result
     is `NULL'.

          mysql> SELECT CONCAT_WS(',','First name','Second name','Last Name');
                  -> 'First name,Second name,Last Name'
          mysql> SELECT CONCAT_WS(',','First name',NULL,'Last Name');
                  -> 'First name,Last Name'

     `CONCAT_WS()' does not skip empty strings. However, it does skip
     any `NULL' values after the separator argument.

   *  `ELT(N,STR1,STR2,STR3,...)'

     Returns STR1 if N = `1', STR2 if N = `2', and so on. Returns
     `NULL' if N is less than `1' or greater than the number of
     arguments.  `ELT()' is the complement of `FIELD()'.

          mysql> SELECT ELT(1, 'ej', 'Heja', 'hej', 'foo');
                  -> 'ej'
          mysql> SELECT ELT(4, 'ej', 'Heja', 'hej', 'foo');
                  -> 'foo'

   *  `EXPORT_SET(BITS,ON,OFF[,SEPARATOR[,NUMBER_OF_BITS]])'

     Returns a string such that for every bit set in the value BITS,
     you get an ON string and for every bit not set in the value, you
     get an OFF string. Bits in BITS are examined from right to left
     (from low-order to high-order bits).  Strings are added to the
     result from left to right, separated by the SEPARATOR string (the
     default being the comma character ``,''). The number of bits
     examined is given by NUMBER_OF_BITS (defaults to 64).

          mysql> SELECT EXPORT_SET(5,'Y','N',',',4);
                  -> 'Y,N,Y,N'
          mysql> SELECT EXPORT_SET(6,'1','0',',',10);
                  -> '0,1,1,0,0,0,0,0,0,0'

   *  `FIELD(STR,STR1,STR2,STR3,...)'

     Returns the index (position) of STR in the STR1, STR2, STR3, `...'
     list.  Returns `0' if STR is not found.

     If all arguments to `FIELD()' are strings, all arguments are
     compared as strings. If all arguments are numbers, they are
     compared as numbers.  Otherwise, the arguments are compared as
     double.

     If STR is `NULL', the return value is `0' because `NULL' fails
     equality comparison with any value. `FIELD()' is the complement of
     `ELT()'.

          mysql> SELECT FIELD('ej', 'Hej', 'ej', 'Heja', 'hej', 'foo');
                  -> 2
          mysql> SELECT FIELD('fo', 'Hej', 'ej', 'Heja', 'hej', 'foo');
                  -> 0

   *  `FIND_IN_SET(STR,STRLIST)'

     Returns a value in the range of 1 to N if the string STR is in the
     string list STRLIST consisting of N substrings. A string list is a
     string composed of substrings separated by ``,'' characters. If
     the first argument is a constant string and the second is a column
     of type *Note `SET': set, the `FIND_IN_SET()' function is
     optimized to use bit arithmetic. Returns `0' if STR is not in
     STRLIST or if STRLIST is the empty string.  Returns `NULL' if
     either argument is `NULL'. This function does not work properly if
     the first argument contains a comma (``,'') character.

          mysql> SELECT FIND_IN_SET('b','a,b,c,d');
                  -> 2

   *  `FORMAT(X,D)'

     Formats the number X to a format like `'#,###,###.##'', rounded to
     D decimal places, and returns the result as a string. If D is `0',
     the result has no decimal point or fractional part.

          mysql> SELECT FORMAT(12332.123456, 4);
                  -> '12,332.1235'
          mysql> SELECT FORMAT(12332.1,4);
                  -> '12,332.1000'
          mysql> SELECT FORMAT(12332.2,0);
                  -> '12,332'

   *  `HEX(N_OR_S)'

     If N_OR_S is a number, returns a string representation of the
     hexadecimal value of N, where N is a longlong (*Note `BIGINT':
     numeric-types.) number. This is equivalent to `CONV(N,10,16)'.

     If N_OR_S is a string, returns a hexadecimal string representation
     of N_OR_S where each character in N_OR_S is converted to two
     hexadecimal digits. The inverse of this operation is performed by
     the `UNHEX()' function.

          mysql> SELECT HEX(255);
                  -> 'FF'
          mysql> SELECT 0x616263;
                  -> 'abc'
          mysql> SELECT HEX('abc');
                  -> 616263

   *  `INSERT(STR,POS,LEN,NEWSTR)'

     Returns the string STR, with the substring beginning at position
     POS and LEN characters long replaced by the string NEWSTR. Returns
     the original string if POS is not within the length of the string.
     Replaces the rest of the string from position POS if LEN is not
     within the length of the rest of the string. Returns `NULL' if any
     argument is `NULL'.

          mysql> SELECT INSERT('Quadratic', 3, 4, 'What');
                  -> 'QuWhattic'
          mysql> SELECT INSERT('Quadratic', -1, 4, 'What');
                  -> 'Quadratic'
          mysql> SELECT INSERT('Quadratic', 3, 100, 'What');
                  -> 'QuWhat'

     This function is multi-byte safe.

   *  `INSTR(STR,SUBSTR)'

     Returns the position of the first occurrence of substring SUBSTR
     in string STR. This is the same as the two-argument form of
     `LOCATE()', except that the order of the arguments is reversed.

          mysql> SELECT INSTR('foobarbar', 'bar');
                  -> 4
          mysql> SELECT INSTR('xbar', 'foobar');
                  -> 0

     This function is multi-byte safe, and is case sensitive only if at
     least one argument is a binary string.

   *  `LCASE(STR)'

     `LCASE()' is a synonym for `LOWER()'.

   *  `LEFT(STR,LEN)'

     Returns the leftmost LEN characters from the string STR, or `NULL'
     if any argument is `NULL'.

          mysql> SELECT LEFT('foobarbar', 5);
                  -> 'fooba'

   *  `LENGTH(STR)'

     Returns the length of the string STR, measured in bytes. A
     multi-byte character counts as multiple bytes. This means that for
     a string containing five two-byte characters, `LENGTH()' returns
     `10', whereas `CHAR_LENGTH()' returns `5'.

          mysql> SELECT LENGTH('text');
                  -> 4

   *  `LOAD_FILE(FILE_NAME)'

     Reads the file and returns the file contents as a string. To use
     this function, the file must be located on the server host, you
     must specify the full path name to the file, and you must have the
     `FILE' privilege.  The file must be readable by all and its size
     less than `max_allowed_packet' bytes. If the `secure_file_priv'
     system variable is set to a non-empty directory name, the file to
     be loaded must be located in that directory.

     If the file does not exist or cannot be read because one of the
     preceding conditions is not satisfied, the function returns `NULL'.

     The `character_set_filesystem' system variable controls
     interpretation of file names that are given as literal strings.

          mysql> UPDATE t
                      SET blob_col=LOAD_FILE('/tmp/picture')
                      WHERE id=1;

   *  `LOCATE(SUBSTR,STR)', `LOCATE(SUBSTR,STR,POS)'

     The first syntax returns the position of the first occurrence of
     substring SUBSTR in string STR. The second syntax returns the
     position of the first occurrence of substring SUBSTR in string
     STR, starting at position POS. Returns `0' if SUBSTR is not in STR.

          mysql> SELECT LOCATE('bar', 'foobarbar');
                  -> 4
          mysql> SELECT LOCATE('xbar', 'foobar');
                  -> 0
          mysql> SELECT LOCATE('bar', 'foobarbar', 5);
                  -> 7

     This function is multi-byte safe, and is case-sensitive only if at
     least one argument is a binary string.

   *  `LOWER(STR)'

     Returns the string STR with all characters changed to lowercase
     according to the current character set mapping. The default is
     `latin1' (cp1252 West European).

          mysql> SELECT LOWER('QUADRATICALLY');
                  -> 'quadratically'

     `LOWER()' (and `UPPER()') are ineffective when applied to binary
     strings (*Note `BINARY': binary-varbinary, *Note `VARBINARY':
     binary-varbinary, *Note `BLOB': blob.). To perform lettercase
     conversion, convert the string to a non-binary string:

          mysql> SET @str = BINARY 'New York';
          mysql> SELECT LOWER(@str), LOWER(CONVERT(@str USING latin1));
          +-------------+-----------------------------------+
          | LOWER(@str) | LOWER(CONVERT(@str USING latin1)) |
          +-------------+-----------------------------------+
          | New York    | new york                          |
          +-------------+-----------------------------------+

     This function is multi-byte safe.

   *  `LPAD(STR,LEN,PADSTR)'

     Returns the string STR, left-padded with the string PADSTR to a
     length of LEN characters. If STR is longer than LEN, the return
     value is shortened to LEN characters.

          mysql> SELECT LPAD('hi',4,'??');
                  -> '??hi'
          mysql> SELECT LPAD('hi',1,'??');
                  -> 'h'

   *  `LTRIM(STR)'

     Returns the string STR with leading space characters removed.

          mysql> SELECT LTRIM('  barbar');
                  -> 'barbar'

     This function is multi-byte safe.

   *  `MAKE_SET(BITS,STR1,STR2,...)'

     Returns a set value (a string containing substrings separated by
     ``,'' characters) consisting of the strings that have the
     corresponding bit in BITS set.  STR1 corresponds to bit 0, STR2 to
     bit 1, and so on.  `NULL' values in STR1, STR2, `...' are not
     appended to the result.

          mysql> SELECT MAKE_SET(1,'a','b','c');
                  -> 'a'
          mysql> SELECT MAKE_SET(1 | 4,'hello','nice','world');
                  -> 'hello,world'
          mysql> SELECT MAKE_SET(1 | 4,'hello','nice',NULL,'world');
                  -> 'hello'
          mysql> SELECT MAKE_SET(0,'a','b','c');
                  -> ''

   *  `MID(STR,POS,LEN)'

     `MID(STR,POS,LEN)' is a synonym for `SUBSTRING(STR,POS,LEN)'.

   *  `OCTET_LENGTH(STR)'

     `OCTET_LENGTH()' is a synonym for `LENGTH()'.

   *  `ORD(STR)'

     If the leftmost character of the string STR is a multi-byte
     character, returns the code for that character, calculated from the
     numeric values of its constituent bytes using this formula:

            (1st byte code)
          + (2nd byte code x 256)
          + (3rd byte code x 256^2) ...

     If the leftmost character is not a multi-byte character, `ORD()'
     returns the same value as the `ASCII()' function.

          mysql> SELECT ORD('2');
                  -> 50

   *  `POSITION(SUBSTR IN STR)'

     `POSITION(SUBSTR IN STR)' is a synonym for `LOCATE(SUBSTR,STR)'.

   *  `QUOTE(STR)'

     Quotes a string to produce a result that can be used as a properly
     escaped data value in an SQL statement. The string is returned
     enclosed by single quotes and with each instance of single quote
     (``'''), backslash (``\''), ASCII `NUL', and Control-Z preceded by
     a backslash.  If the argument is `NULL', the return value is the
     word `NULL' without enclosing single quotes.

          mysql> SELECT QUOTE('Don\'t!');
                  -> 'Don\'t!'
          mysql> SELECT QUOTE(NULL);
                  -> NULL

   *  `REPEAT(STR,COUNT)'

     Returns a string consisting of the string STR repeated COUNT
     times. If COUNT is less than 1, returns an empty string. Returns
     `NULL' if STR or COUNT are `NULL'.

          mysql> SELECT REPEAT('MySQL', 3);
                  -> 'MySQLMySQLMySQL'

   *  `REPLACE(STR,FROM_STR,TO_STR)'

     Returns the string STR with all occurrences of the string FROM_STR
     replaced by the string TO_STR.  `REPLACE()' performs a
     case-sensitive match when searching for FROM_STR.

          mysql> SELECT REPLACE('www.mysql.com', 'w', 'Ww');
                  -> 'WwWwWw.mysql.com'

     This function is multi-byte safe.

   *  `REVERSE(STR)'

     Returns the string STR with the order of the characters reversed.

          mysql> SELECT REVERSE('abc');
                  -> 'cba'

     This function is multi-byte safe.

   *  `RIGHT(STR,LEN)'

     Returns the rightmost LEN characters from the string STR, or
     `NULL' if any argument is `NULL'.

          mysql> SELECT RIGHT('foobarbar', 4);
                  -> 'rbar'

     This function is multi-byte safe.

   *  `RPAD(STR,LEN,PADSTR)'

     Returns the string STR, right-padded with the string PADSTR to a
     length of LEN characters. If STR is longer than LEN, the return
     value is shortened to LEN characters.

          mysql> SELECT RPAD('hi',5,'?');
                  -> 'hi???'
          mysql> SELECT RPAD('hi',1,'?');
                  -> 'h'

     This function is multi-byte safe.

   *  `RTRIM(STR)'

     Returns the string STR with trailing space characters removed.

          mysql> SELECT RTRIM('barbar   ');
                  -> 'barbar'

     This function is multi-byte safe.

   *  `SOUNDEX(STR)'

     Returns a soundex string from STR.  Two strings that sound almost
     the same should have identical soundex strings. A standard soundex
     string is four characters long, but the `SOUNDEX()' function
     returns an arbitrarily long string. You can use `SUBSTRING()' on
     the result to get a standard soundex string. All non-alphabetic
     characters in STR are ignored. All international alphabetic
     characters outside the A-Z range are treated as vowels.

     *Important*:

     When using `SOUNDEX()', you should be aware of the following
     limitations:

        * This function, as currently implemented, is intended to work
          well with strings that are in the English language only.
          Strings in other languages may not produce reliable results.

        * This function is not guaranteed to provide consistent results
          with strings that use multi-byte character sets, including
          `utf-8'.

          We hope to remove these limitations in a future release.  See
          Bug#22638 (http://bugs.mysql.com/22638) for more information.

          mysql> SELECT SOUNDEX('Hello');
                  -> 'H400'
          mysql> SELECT SOUNDEX('Quadratically');
                  -> 'Q36324'

     *Note*:

     This function implements the original Soundex algorithm, not the
     more popular enhanced version (also described by D.  Knuth). The
     difference is that original version discards vowels first and
     duplicates second, whereas the enhanced version discards
     duplicates first and vowels second.

   *  `EXPR1 SOUNDS LIKE EXPR2'

     This is the same as `SOUNDEX(EXPR1) = SOUNDEX(EXPR2)'.

   *  `SPACE(N)'

     Returns a string consisting of N space characters.

          mysql> SELECT SPACE(6);
                  -> '      '

   *  `SUBSTR(STR,POS)', `SUBSTR(STR FROM POS)', `SUBSTR(STR,POS,LEN)',
     `SUBSTR(STR FROM POS FOR LEN)'

     `SUBSTR()' is a synonym for `SUBSTRING()'.

   *  `SUBSTRING(STR,POS)', `SUBSTRING(STR FROM POS)',
     `SUBSTRING(STR,POS,LEN)', `SUBSTRING(STR FROM POS FOR LEN)'

     The forms without a LEN argument return a substring from string STR
     starting at position POS. The forms with a LEN argument return a
     substring LEN characters long from string STR, starting at position
     POS. The forms that use `FROM' are standard SQL syntax. It is also
     possible to use a negative value for POS. In this case, the
     beginning of the substring is POS characters from the end of the
     string, rather than the beginning. A negative value may be used
     for POS in any of the forms of this function.

     For all forms of `SUBSTRING()', the position of the first
     character in the string from which the substring is to be
     extracted is reckoned as `1'.

          mysql> SELECT SUBSTRING('Quadratically',5);
                  -> 'ratically'
          mysql> SELECT SUBSTRING('foobarbar' FROM 4);
                  -> 'barbar'
          mysql> SELECT SUBSTRING('Quadratically',5,6);
                  -> 'ratica'
          mysql> SELECT SUBSTRING('Sakila', -3);
                  -> 'ila'
          mysql> SELECT SUBSTRING('Sakila', -5, 3);
                  -> 'aki'
          mysql> SELECT SUBSTRING('Sakila' FROM -4 FOR 2);
                  -> 'ki'

     This function is multi-byte safe.

     If LEN is less than 1, the result is the empty string.

   *  `SUBSTRING_INDEX(STR,DELIM,COUNT)'

     Returns the substring from string STR before COUNT occurrences of
     the delimiter DELIM. If COUNT is positive, everything to the left
     of the final delimiter (counting from the left) is returned. If
     COUNT is negative, everything to the right of the final delimiter
     (counting from the right) is returned.  `SUBSTRING_INDEX()'
     performs a case-sensitive match when searching for DELIM.

          mysql> SELECT SUBSTRING_INDEX('www.mysql.com', '.', 2);
                  -> 'www.mysql'
          mysql> SELECT SUBSTRING_INDEX('www.mysql.com', '.', -2);
                  -> 'mysql.com'

     This function is multi-byte safe.

   *  `TRIM([{BOTH | LEADING | TRAILING} [REMSTR] FROM] STR)',
     `TRIM([REMSTR FROM] STR)'

     Returns the string STR with all REMSTR prefixes or suffixes
     removed. If none of the specifiers `BOTH', `LEADING', or
     `TRAILING' is given, `BOTH' is assumed.  REMSTR is optional and,
     if not specified, spaces are removed.

          mysql> SELECT TRIM('  bar   ');
                  -> 'bar'
          mysql> SELECT TRIM(LEADING 'x' FROM 'xxxbarxxx');
                  -> 'barxxx'
          mysql> SELECT TRIM(BOTH 'x' FROM 'xxxbarxxx');
                  -> 'bar'
          mysql> SELECT TRIM(TRAILING 'xyz' FROM 'barxxyz');
                  -> 'barx'

     This function is multi-byte safe.

   *  `UCASE(STR)'

     `UCASE()' is a synonym for `UPPER()'.

   *  `UNHEX(STR)'

     Performs the inverse operation of `HEX(STR)'.  That is, it
     interprets each pair of hexadecimal digits in the argument as a
     number and converts it to the character represented by the number.
     The resulting characters are returned as a binary string.

          mysql> SELECT UNHEX('4D7953514C');
                  -> 'MySQL'
          mysql> SELECT 0x4D7953514C;
                  -> 'MySQL'
          mysql> SELECT UNHEX(HEX('string'));
                  -> 'string'
          mysql> SELECT HEX(UNHEX('1267'));
                  -> '1267'

     The characters in the argument string must be legal hexadecimal
     digits: `'0'' ..  `'9'', `'A'' ..  `'F'', `'a'' ..  `'f''. If
     `UNHEX()' encounters any non-hexadecimal digits in the argument,
     it returns `NULL':

          mysql> SELECT UNHEX('GG');
          +-------------+
          | UNHEX('GG') |
          +-------------+
          | NULL        |
          +-------------+

     A `NULL' result can occur if the argument to `UNHEX()' is a *Note
     `BINARY': binary-varbinary. column, because values are padded with
     0x00 bytes when stored but those bytes are not stripped on
     retrieval. For example `'aa'' is stored into a `CHAR(3)' column as
     `'aa '' and retrieved as `'aa'' (with the trailing pad space
     stripped), so `UNHEX()' for the column value returns `'A''. By
     contrast `'aa'' is stored into a `BINARY(3)' column as `'aa\0''
     and retrieved as `'aa\0'' (with the trailing pad `0x00' byte not
     stripped).  `'\0'' is not a legal hexadecimal digit, so `UNHEX()'
     for the column value returns `NULL'.

   *  `UPPER(STR)'

     Returns the string STR with all characters changed to uppercase
     according to the current character set mapping. The default is
     `latin1' (cp1252 West European).

          mysql> SELECT UPPER('Hej');
                  -> 'HEJ'

     `UPPER()' is ineffective when applied to binary strings (*Note
     `BINARY': binary-varbinary, *Note `VARBINARY': binary-varbinary,
     *Note `BLOB': blob.). The description of `LOWER()' shows how to
     perform lettercase conversion of binary strings.

     This function is multi-byte safe.

   *  `WEIGHT_STRING(STR [AS {CHAR|BINARY}(N)] [LEVEL LEVELS] [FLAGS])'

     `LEVELS: N [ASC|DESC|REVERSE] [, N [ASC|DESC|REVERSE]] ...'

     This function returns the weight string for the input string.  The
     return value is a binary string that represents the sorting and
     comparison value of the string. It has these properties:

        * If `WEIGHT_STRING(STR1)' = `WEIGHT_STRING(STR2)', then `STR1 =
          STR2' (STR1 and STR2 are considered equal)

        * If `WEIGHT_STRING(STR1)' < `WEIGHT_STRING(STR2)', then `STR1 <
          STR2' (STR1 sorts before STR2)

     `WEIGHT_STRING()' can be used for testing and debugging of
     collations, especially if you are adding a new collation. See
     *Note adding-collation::.

     The input string, STR, is a string expression. If the input is a
     non-binary (character) string such as a *Note `CHAR': char, *Note
     `VARCHAR': char, or *Note `TEXT': blob. value, the return value
     contains the collation weights for the string. If the input is a
     binary (byte) string such as a *Note `BINARY': binary-varbinary,
     *Note `VARBINARY': binary-varbinary, or *Note `BLOB': blob. value,
     the return value is the same as the input (the weight for each
     byte in a binary string is the byte value). If the input is `NULL',
     `WEIGHT_STRING()' returns `NULL'.

     Examples:

          mysql> SET @s = _latin1 'AB' COLLATE latin1_swedish_ci;
          mysql> SELECT @s, HEX(@s), HEX(WEIGHT_STRING(@s));
          +------+---------+------------------------+
          | @s   | HEX(@s) | HEX(WEIGHT_STRING(@s)) |
          +------+---------+------------------------+
          | AB   | 4142    | 4142                   |
          +------+---------+------------------------+

          mysql> SET @s = _latin1 'ab' COLLATE latin1_swedish_ci;
          mysql> SELECT @s, HEX(@s), HEX(WEIGHT_STRING(@s));
          +------+---------+------------------------+
          | @s   | HEX(@s) | HEX(WEIGHT_STRING(@s)) |
          +------+---------+------------------------+
          | ab   | 6162    | 4142                   |
          +------+---------+------------------------+

          mysql> SET @s = CAST('AB' AS BINARY);
          mysql> SELECT @s, HEX(@s), HEX(WEIGHT_STRING(@s));
          +------+---------+------------------------+
          | @s   | HEX(@s) | HEX(WEIGHT_STRING(@s)) |
          +------+---------+------------------------+
          | AB   | 4142    | 4142                   |
          +------+---------+------------------------+

          mysql> SET @s = CAST('ab' AS BINARY);
          mysql> SELECT @s, HEX(@s), HEX(WEIGHT_STRING(@s));
          +------+---------+------------------------+
          | @s   | HEX(@s) | HEX(WEIGHT_STRING(@s)) |
          +------+---------+------------------------+
          | ab   | 6162    | 6162                   |
          +------+---------+------------------------+

     The preceding examples use `HEX()' to display the
     `WEIGHT_STRING()' result. Because the result is a binary value,
     `HEX()' can be especially useful when the result contains
     non-printing values, to display it in printable form:

          mysql> SET @s = CONVERT(0xC39F USING utf8) COLLATE utf8_czech_ci;
          mysql> SELECT HEX(WEIGHT_STRING(@s));
          +------------------------+
          | HEX(WEIGHT_STRING(@s)) |
          +------------------------+
          | 0FEA0FEA               |
          +------------------------+

     For non-`NULL' return values, the data type of the value is *Note
     `VARBINARY': binary-varbinary. if its length is within the maximum
     length for *Note `VARBINARY': binary-varbinary, otherwise the data
     type is *Note `BLOB': blob.

     The `AS' clause may be given to cast the input string to a
     non-binary or binary string and to force it to a given length:

        * `AS CHAR(N)' casts the string to a non-binary string and pads
          it on the right with spaces to a length of N characters.  N
          must be at least 1. If N is less than the length of the input
          string, the string is truncated to N characters. No warning
          occurs for truncation.

        * `AS BINARY(N)' is similar but casts the string to a binary
          string, N is measured in bytes (not characters), and padding
          uses `0x00' bytes (not spaces).

          mysql> SELECT HEX(WEIGHT_STRING('ab' AS CHAR(4)));
          +-------------------------------------+
          | HEX(WEIGHT_STRING('ab' AS CHAR(4))) |
          +-------------------------------------+
          | 41422020                            |
          +-------------------------------------+

          mysql> SELECT HEX(WEIGHT_STRING('ab' AS BINARY(4)));
          +---------------------------------------+
          | HEX(WEIGHT_STRING('ab' AS BINARY(4))) |
          +---------------------------------------+
          | 61620000                              |
          +---------------------------------------+

     The `LEVEL' clause may be given to specify that the return value
     should contain weights for specific collation levels.

     The LEVELS specifier following the `LEVEL' keyword may be given
     either as a list of one or more integers separated by commas, or
     as a range of two integers separated by a dash. Whitespace around
     the punctuation characters does not matter.

     Examples:

          LEVEL 1
          LEVEL 2, 3, 5
          LEVEL 1-3

     Any level less than 1 is treated as 1. Any level greater than the
     maximum for the input string collation is treated as maximum for
     the collation. The maximum varies per collation, but is never
     greater than 6.

     In a list of levels, levels must be given in increasing order.  In
     a range of levels, if the second number is less than the first, it
     is treated as the first number (for example, 4-2 is the same as
     4-4).

     If the `LEVEL' clause is omitted, MySQL assumes `LEVEL 1 - MAX',
     where MAX is the maximum level for the collation.

     If `LEVEL' is specified using list syntax (not range syntax), any
     level number can be followed by these modifiers:

        * `ASC': Return the weights without modification. This is the
          default.

        * `DESC': Return bitwise-inverted weights (for example, `0x78f0
          DESC' = `0x870f').

        * `REVERSE': Return the weights in reverse order (that is,the
          weights for the reversed string, with the first character
          last and the last first).

     Examples:

          mysql> SELECT HEX(WEIGHT_STRING(0x007fff LEVEL 1));
          +--------------------------------------+
          | HEX(WEIGHT_STRING(0x007fff LEVEL 1)) |
          +--------------------------------------+
          | 007FFF                               |
          +--------------------------------------+

          mysql> SELECT HEX(WEIGHT_STRING(0x007fff LEVEL 1 DESC));
          +-------------------------------------------+
          | HEX(WEIGHT_STRING(0x007fff LEVEL 1 DESC)) |
          +-------------------------------------------+
          | FF8000                                    |
          +-------------------------------------------+

          mysql> SELECT HEX(WEIGHT_STRING(0x007fff LEVEL 1 REVERSE));
          +----------------------------------------------+
          | HEX(WEIGHT_STRING(0x007fff LEVEL 1 REVERSE)) |
          +----------------------------------------------+
          | FF7F00                                       |
          +----------------------------------------------+

          mysql> SELECT HEX(WEIGHT_STRING(0x007fff LEVEL 1 DESC REVERSE));
          +---------------------------------------------------+
          | HEX(WEIGHT_STRING(0x007fff LEVEL 1 DESC REVERSE)) |
          +---------------------------------------------------+
          | 0080FF                                            |
          +---------------------------------------------------+

     The FLAGS clause currently is unused.


File: manual.info,  Node: string-comparison-functions,  Next: regexp,  Prev: string-functions,  Up: string-functions

11.4.1 String Comparison Functions
----------------------------------

*Name*                        *Description*
`LIKE'                        Simple pattern matching
`NOT LIKE'                    Negation of simple pattern matching
`STRCMP()'                    Compare two strings

If a string function is given a binary string as an argument, the
resulting string is also a binary string. A number converted to a
string is treated as a binary string. This affects only comparisons.

Normally, if any expression in a string comparison is case sensitive,
the comparison is performed in case-sensitive fashion.

   *  `EXPR LIKE PAT [ESCAPE 'ESCAPE_CHAR']'

     Pattern matching using SQL simple regular expression comparison.
     Returns `1' (`TRUE') or `0' (`FALSE'). If either EXPR or PAT is
     `NULL', the result is `NULL'.

     The pattern need not be a literal string. For example, it can be
     specified as a string expression or table column.

     Per the SQL standard, `LIKE' performs matching on a per-character
     basis, thus it can produce results different from the `='
     comparison operator:

          mysql> SELECT 'a"' LIKE 'ae' COLLATE latin1_german2_ci;
          +-----------------------------------------+
          | 'a"' LIKE 'ae' COLLATE latin1_german2_ci |
          +-----------------------------------------+
          |                                       0 |
          +-----------------------------------------+
          mysql> SELECT 'a"' = 'ae' COLLATE latin1_german2_ci;
          +--------------------------------------+
          | 'a"' = 'ae' COLLATE latin1_german2_ci |
          +--------------------------------------+
          |                                    1 |
          +--------------------------------------+

     In particular, trailing spaces are significant, which is not true
     for *Note `CHAR': char. or *Note `VARCHAR': char. comparisons
     performed with the `=' operator:

          mysql> SELECT 'a' = 'a ', 'a' LIKE 'a ';
          +------------+---------------+
          | 'a' = 'a ' | 'a' LIKE 'a ' |
          +------------+---------------+
          |          1 |             0 |
          +------------+---------------+
          1 row in set (0.00 sec)

     With `LIKE' you can use the following two wildcard characters in
     the pattern.

     *Character*   *Description*
     `%'           Matches any number of characters, even zero characters
     `_'           Matches exactly one character

          mysql> SELECT 'David!' LIKE 'David_';
                  -> 1
          mysql> SELECT 'David!' LIKE '%D%v%';
                  -> 1

     To test for literal instances of a wildcard character, precede it
     by the escape character. If you do not specify the `ESCAPE'
     character, ``\'' is assumed.

     *String*      *Description*
     `\%'          Matches one ``%'' character
     `\_'          Matches one ``_'' character

          mysql> SELECT 'David!' LIKE 'David\_';
                  -> 0
          mysql> SELECT 'David_' LIKE 'David\_';
                  -> 1

     To specify a different escape character, use the `ESCAPE' clause:

          mysql> SELECT 'David_' LIKE 'David|_' ESCAPE '|';
                  -> 1

     The escape sequence should be empty or one character long.  If the
     `NO_BACKSLASH_ESCAPES' SQL mode is enabled, the sequence cannot be
     empty.

     The following two statements illustrate that string comparisons
     are not case sensitive unless one of the operands is a binary
     string:

          mysql> SELECT 'abc' LIKE 'ABC';
                  -> 1
          mysql> SELECT 'abc' LIKE BINARY 'ABC';
                  -> 0

     In MySQL, `LIKE' is allowed on numeric expressions. (This is an
     extension to the standard SQL `LIKE'.)

          mysql> SELECT 10 LIKE '1%';
                  -> 1

     *Note*:

     Because MySQL uses C escape syntax in strings (for example, ``\n''
     to represent a newline character), you must double any ``\'' that
     you use in `LIKE' strings. For example, to search for ``\n'',
     specify it as ``\\n''. To search for ``\'', specify it as
     ``\\\\''; this is because the backslashes are stripped once by the
     parser and again when the pattern match is made, leaving a single
     backslash to be matched against. (Exception: At the end of the
     pattern string, backslash can be specified as ``\\''. At the end
     of the string, backslash stands for itself because there is
     nothing following to escape.)

   *  `EXPR NOT LIKE PAT [ESCAPE 'ESCAPE_CHAR']'

     This is the same as `NOT (EXPR LIKE PAT [ESCAPE 'ESCAPE_CHAR'])'.

     *Note*:

     Aggregate queries involving `NOT LIKE' comparisons with columns
     containing `NULL' may yield unexpected results. For example,
     consider the following table and data:

          CREATE TABLE foo (bar VARCHAR(10));

          INSERT INTO foo VALUES (NULL), (NULL);

     The query `SELECT COUNT(*) FROM foo WHERE bar LIKE '%baz%';'
     returns `0'. You might assume that `SELECT COUNT(*) FROM foo WHERE
     bar NOT LIKE '%baz%';' would return `2'. However, this is not the
     case: The second query returns `0'. This is because `NULL NOT LIKE
     EXPR' always returns `NULL', regardless of the value of EXPR. The
     same is true for aggregate queries involving `NULL' and
     comparisons using `NOT RLIKE' or `NOT REGEXP'. In such cases, you
     must test explicitly for `NOT NULL' using `OR' (and not `AND'), as
     shown here:

          SELECT COUNT(*) FROM foo WHERE bar NOT LIKE '%baz%' OR bar IS NULL;

   *  `STRCMP(EXPR1,EXPR2)'

     `STRCMP()' returns `0' if the strings are the same, `-1' if the
     first argument is smaller than the second according to the current
     sort order, and `1' otherwise.

          mysql> SELECT STRCMP('text', 'text2');
                  -> -1
          mysql> SELECT STRCMP('text2', 'text');
                  -> 1
          mysql> SELECT STRCMP('text', 'text');
                  -> 0

     `STRCMP()' uses the current character set when performing
     comparisons. This makes the default comparison behavior case
     insensitive unless one or both of the operands are binary strings.


File: manual.info,  Node: regexp,  Prev: string-comparison-functions,  Up: string-functions

11.4.2 Regular Expressions
--------------------------

*Name*                        *Description*
`NOT REGEXP'                  Negation of REGEXP
`REGEXP'                      Pattern matching using regular expressions
`RLIKE'                       Synonym for REGEXP

A regular expression is a powerful way of specifying a pattern for a
complex search.

MySQL uses Henry Spencer's implementation of regular expressions, which
is aimed at conformance with POSIX 1003.2.  See *Note credits::. MySQL
uses the extended version to support pattern-matching operations
performed with the `REGEXP' operator in SQL statements.

This section summarizes, with examples, the special characters and
constructs that can be used in MySQL for `REGEXP' operations. It does
not contain all the details that can be found in Henry Spencer's
`regex(7)' manual page. That manual page is included in MySQL source
distributions, in the `regex.7' file under the `regex' directory. See
also *Note pattern-matching::.

   *  `EXPR NOT REGEXP PAT', `EXPR NOT RLIKE PAT'

     This is the same as `NOT (EXPR REGEXP PAT)'.

   *  `EXPR REGEXP PAT', `EXPR RLIKE PAT'

     Performs a pattern match of a string expression EXPR against a
     pattern PAT. The pattern can be an extended regular expression.
     The syntax for regular expressions is discussed in *Note regexp::.
     Returns `1' if EXPR matches PAT; otherwise it returns `0'. If
     either EXPR or PAT is `NULL', the result is `NULL'.  `RLIKE' is a
     synonym for `REGEXP', provided for `mSQL' compatibility.

     The pattern need not be a literal string. For example, it can be
     specified as a string expression or table column.

     *Note*:

     Because MySQL uses the C escape syntax in strings (for example,
     ``\n'' to represent the newline character), you must double any
     ``\'' that you use in your `REGEXP' strings.

     `REGEXP' is not case sensitive, except when used with binary
     strings.

          mysql> SELECT 'Monty!' REGEXP 'm%y%%';
                  -> 0
          mysql> SELECT 'Monty!' REGEXP '.*';
                  -> 1
          mysql> SELECT 'new*\n*line' REGEXP 'new\\*.\\*line';
                  -> 1
          mysql> SELECT 'a' REGEXP 'A', 'a' REGEXP BINARY 'A';
                  -> 1  0
          mysql> SELECT 'a' REGEXP '^[a-d]';
                  -> 1

     `REGEXP' and `RLIKE' use the current character set when deciding
     the type of a character. The default is `latin1' (cp1252 West
     European).

     *Warning*:

     The `REGEXP' and `RLIKE' operators work in byte-wise fashion, so
     they are not multi-byte safe and may produce unexpected results
     with multi-byte character sets. In addition, these operators
     compare characters by their byte values and accented characters
     may not compare as equal even if a given collation treats them as
     equal.

A regular expression describes a set of strings. The simplest regular
expression is one that has no special characters in it.  For example,
the regular expression `hello' matches `hello' and nothing else.

Non-trivial regular expressions use certain special constructs so that
they can match more than one string. For example, the regular
expression `hello|word' matches either the string `hello' or the string
`word'.

As a more complex example, the regular expression `B[an]*s' matches any
of the strings `Bananas', `Baaaaas', `Bs', and any other string
starting with a `B', ending with an `s', and containing any number of
`a' or `n' characters in between.

A regular expression for the `REGEXP' operator may use any of the
following special characters and constructs:

   * `^'

     Match the beginning of a string.

          mysql> SELECT 'fo\nfo' REGEXP '^fo$';                   -> 0
          mysql> SELECT 'fofo' REGEXP '^fo';                      -> 1

   * `$'

     Match the end of a string.

          mysql> SELECT 'fo\no' REGEXP '^fo\no$';                 -> 1
          mysql> SELECT 'fo\no' REGEXP '^fo$';                    -> 0

   * `.'

     Match any character (including carriage return and newline).

          mysql> SELECT 'fofo' REGEXP '^f.*$';                    -> 1
          mysql> SELECT 'fo\r\nfo' REGEXP '^f.*$';                -> 1

   * `a*'

     Match any sequence of zero or more `a' characters.

          mysql> SELECT 'Ban' REGEXP '^Ba*n';                     -> 1
          mysql> SELECT 'Baaan' REGEXP '^Ba*n';                   -> 1
          mysql> SELECT 'Bn' REGEXP '^Ba*n';                      -> 1

   * `a+'

     Match any sequence of one or more `a' characters.

          mysql> SELECT 'Ban' REGEXP '^Ba+n';                     -> 1
          mysql> SELECT 'Bn' REGEXP '^Ba+n';                      -> 0

   * `a?'

     Match either zero or one `a' character.

          mysql> SELECT 'Bn' REGEXP '^Ba?n';                      -> 1
          mysql> SELECT 'Ban' REGEXP '^Ba?n';                     -> 1
          mysql> SELECT 'Baan' REGEXP '^Ba?n';                    -> 0

   * `de|abc'

     Match either of the sequences `de' or `abc'.

          mysql> SELECT 'pi' REGEXP 'pi|apa';                     -> 1
          mysql> SELECT 'axe' REGEXP 'pi|apa';                    -> 0
          mysql> SELECT 'apa' REGEXP 'pi|apa';                    -> 1
          mysql> SELECT 'apa' REGEXP '^(pi|apa)$';                -> 1
          mysql> SELECT 'pi' REGEXP '^(pi|apa)$';                 -> 1
          mysql> SELECT 'pix' REGEXP '^(pi|apa)$';                -> 0

   * `(abc)*'

     Match zero or more instances of the sequence `abc'.

          mysql> SELECT 'pi' REGEXP '^(pi)*$';                    -> 1
          mysql> SELECT 'pip' REGEXP '^(pi)*$';                   -> 0
          mysql> SELECT 'pipi' REGEXP '^(pi)*$';                  -> 1

   * `{1}', `{2,3}'

     `{n}' or `{m,n}' notation provides a more general way of writing
     regular expressions that match many occurrences of the previous
     atom (or `piece') of the pattern. `m' and `n' are integers.

        * `a*'

          Can be written as `a{0,}'.

        * `a+'

          Can be written as `a{1,}'.

        * `a?'

          Can be written as `a{0,1}'.

     To be more precise, `a{n}' matches exactly `n' instances of `a'.
     `a{n,}' matches `n' or more instances of `a'.  `a{m,n}' matches `m'
     through `n' instances of `a', inclusive.

     `m' and `n' must be in the range from `0' to `RE_DUP_MAX' (default
     255), inclusive. If both `m' and `n' are given, `m' must be less
     than or equal to `n'.

          mysql> SELECT 'abcde' REGEXP 'a[bcd]{2}e';              -> 0
          mysql> SELECT 'abcde' REGEXP 'a[bcd]{3}e';              -> 1
          mysql> SELECT 'abcde' REGEXP 'a[bcd]{1,10}e';           -> 1

   * `[a-dX]', `[^a-dX]'

     Matches any character that is (or is not, if ^ is used) either
     `a', `b', `c', `d' or `X'. A `-' character between two other
     characters forms a range that matches all characters from the
     first character to the second. For example, `[0-9]' matches any
     decimal digit.  To include a literal `]' character, it must
     immediately follow the opening bracket `['.  To include a literal
     `-' character, it must be written first or last. Any character
     that does not have a defined special meaning inside a `[]' pair
     matches only itself.

          mysql> SELECT 'aXbc' REGEXP '[a-dXYZ]';                 -> 1
          mysql> SELECT 'aXbc' REGEXP '^[a-dXYZ]$';               -> 0
          mysql> SELECT 'aXbc' REGEXP '^[a-dXYZ]+$';              -> 1
          mysql> SELECT 'aXbc' REGEXP '^[^a-dXYZ]+$';             -> 0
          mysql> SELECT 'gheis' REGEXP '^[^a-dXYZ]+$';            -> 1
          mysql> SELECT 'gheisa' REGEXP '^[^a-dXYZ]+$';           -> 0

   * `[.characters.]'

     Within a bracket expression (written using `[' and `]'), matches
     the sequence of characters of that collating element.
     `characters' is either a single character or a character name like
     `newline'. The following table lists the allowable character names.

     The following table shows the allowable character names and the
     characters that they match. For characters given as numeric
     values, the values are represented in octal.

     *Name*            *Character*       *Name*            *Character*
     `NUL'             `0'               `SOH'             `001'
     `STX'             `002'             `ETX'             `003'
     `EOT'             `004'             `ENQ'             `005'
     `ACK'             `006'             `BEL'             `007'
     `alert'           `007'             `BS'              `010'
     `backspace'       `'\b''            `HT'              `011'
     `tab'             `'\t''            `LF'              `012'
     `newline'         `'\n''            `VT'              `013'
     `vertical-tab'    `'\v''            `FF'              `014'
     `form-feed'       `'\f''            `CR'              `015'
     `carriage-return' `'\r''            `SO'              `016'
     `SI'              `017'             `DLE'             `020'
     `DC1'             `021'             `DC2'             `022'
     `DC3'             `023'             `DC4'             `024'
     `NAK'             `025'             `SYN'             `026'
     `ETB'             `027'             `CAN'             `030'
     `EM'              `031'             `SUB'             `032'
     `ESC'             `033'             `IS4'             `034'
     `FS'              `034'             `IS3'             `035'
     `GS'              `035'             `IS2'             `036'
     `RS'              `036'             `IS1'             `037'
     `US'              `037'             `space'           `' ''
     `exclamation-mark'`'!''             `quotation-mark'  `'"''
     `number-sign'     `'#''             `dollar-sign'     `'$''
     `percent-sign'    `'%''             `ampersand'       `'&''
     `apostrophe'      `'\'''            `left-parenthesis'`'(''
     `right-parenthesis'`')''             `asterisk'        `'*''
     `plus-sign'       `'+''             `comma'           `',''
     `hyphen'          `'-''             `hyphen-minus'    `'-''
     `period'          `'.''             `full-stop'       `'.''
     `slash'           `'/''             `solidus'         `'/''
     `zero'            `'0''             `one'             `'1''
     `two'             `'2''             `three'           `'3''
     `four'            `'4''             `five'            `'5''
     `six'             `'6''             `seven'           `'7''
     `eight'           `'8''             `nine'            `'9''
     `colon'           `':''             `semicolon'       `';''
     `less-than-sign'  `'<''             `equals-sign'     `'=''
     `greater-than-sign'`'>''             `question-mark'   `'?''
     `commercial-at'   `'@''             `left-square-bracket'`'[''
     `backslash'       `'\\''            `reverse-solidus' `'\\''
     `right-square-bracket'`']''             `circumflex'      `'^''
     `circumflex-accent'`'^''             `underscore'      `'_''
     `low-line'        `'_''             `grave-accent'    `'`''
     `left-brace'      `'{''             `left-curly-bracket'`'{''
     `vertical-line'   `'|''             `right-brace'     `'}''
     `right-curly-bracket'`'}''             `tilde'           `'~''
     `DEL'             `177'                               

          mysql> SELECT '~' REGEXP '[[.~.]]';                     -> 1
          mysql> SELECT '~' REGEXP '[[.tilde.]]';                 -> 1

   * `[=character_class=]'

     Within a bracket expression (written using `[' and `]'),
     `[=character_class=]' represents an equivalence class. It matches
     all characters with the same collation value, including itself.
     For example, if `o' and `(+)' are the members of an equivalence
     class, then `[[=o=]]', `[[=(+)=]]', and `[o(+)]' are all
     synonymous. An equivalence class may not be used as an endpoint of
     a range.

   * `[:character_class:]'

     Within a bracket expression (written using `[' and `]'),
     `[:character_class:]' represents a character class that matches
     all characters belonging to that class. The following table lists
     the standard class names. These names stand for the character
     classes defined in the `ctype(3)' manual page. A particular locale
     may provide other class names. A character class may not be used
     as an endpoint of a range.

     `alnum' Alphanumeric characters
     `alpha' Alphabetic characters
     `blank' Whitespace characters
     `cntrl' Control characters
     `digit' Digit characters
     `graph' Graphic characters
     `lower' Lowercase alphabetic characters
     `print' Graphic or space characters
     `punct' Punctuation characters
     `space' Space, tab, newline, and carriage return
     `upper' Uppercase alphabetic characters
     `xdigit'Hexadecimal digit characters

          mysql> SELECT 'justalnums' REGEXP '[[:alnum:]]+';       -> 1
          mysql> SELECT '!!' REGEXP '[[:alnum:]]+';               -> 0

   * `[[:<:]]', `[[:>:]]'

     These markers stand for word boundaries. They match the beginning
     and end of words, respectively. A word is a sequence of word
     characters that is not preceded by or followed by word characters.
     A word character is an alphanumeric character in the `alnum' class
     or an underscore (`_').

          mysql> SELECT 'a word a' REGEXP '[[:<:]]word[[:>:]]';   -> 1
          mysql> SELECT 'a xword a' REGEXP '[[:<:]]word[[:>:]]';  -> 0

To use a literal instance of a special character in a regular
expression, precede it by two backslash (\) characters. The MySQL
parser interprets one of the backslashes, and the regular expression
library interprets the other. For example, to match the string `1+2'
that contains the special `+' character, only the last of the following
regular expressions is the correct one:

     mysql> SELECT '1+2' REGEXP '1+2';                       -> 0
     mysql> SELECT '1+2' REGEXP '1\+2';                      -> 0
     mysql> SELECT '1+2' REGEXP '1\\+2';                     -> 1


File: manual.info,  Node: numeric-functions,  Next: date-and-time-functions,  Prev: string-functions,  Up: functions

11.5 Numeric Functions
======================

* Menu:

* arithmetic-functions::         Arithmetic Operators
* mathematical-functions::       Mathematical Functions

*Name*                        *Description*
`ABS()'                       Return the absolute value
`ACOS()'                      Return the arc cosine
`ASIN()'                      Return the arc sine
`ATAN2()', `ATAN()'           Return the arc tangent of the two arguments
`ATAN()'                      Return the arc tangent
`CEIL()'                      Return the smallest integer value not less
                              than  the argument
`CEILING()'                   Return the smallest integer value not less
                              than  the argument
`CONV()'                      Convert numbers between different number
                              bases
`COS()'                       Return the cosine
`COT()'                       Return the cotangent
`CRC32()'(v4.1.0)             Compute a cyclic redundancy check value
`DEGREES()'                   Convert radians to degrees
`DIV'(v4.1.0)                 Integer division
`/'                           Division operator
`EXP()'                       Raise to the power of
`FLOOR()'                     Return the largest integer value not
                              greater than  the argument
`LN()'                        Return the natural logarithm of the
                              argument
`LOG10()'                     Return the base-10 logarithm of the
                              argument
`LOG2()'                      Return the base-2 logarithm of the argument
`LOG()'                       Return the natural logarithm of the first
                              argument
`-'                           Minus operator
`MOD()'                       Return the remainder
`%'                           Modulo operator
`OCT()'                       Return an octal representation of a
                              decimal  number
`PI()'                        Return the value of pi
`+'                           Addition operator
`POW()'                       Return the argument raised to the
                              specified power
`POWER()'                     Return the argument raised to the
                              specified power
`RADIANS()'                   Return argument converted to radians
`RAND()'                      Return a random floating-point value
`ROUND()'                     Round the argument
`SIGN()'                      Return the sign of the argument
`SIN()'                       Return the sine of the argument
`SQRT()'                      Return the square root of the argument
`TAN()'                       Return the tangent of the argument
`*'                           Times operator
`TRUNCATE()'                  Truncate to specified number of decimal
                              places
`-'                           Change the sign of the argument


File: manual.info,  Node: arithmetic-functions,  Next: mathematical-functions,  Prev: numeric-functions,  Up: numeric-functions

11.5.1 Arithmetic Operators
---------------------------

*Name*                        *Description*
`DIV'(v4.1.0)                 Integer division
`/'                           Division operator
`-'                           Minus operator
`%'                           Modulo operator
`+'                           Addition operator
`*'                           Times operator
`-'                           Change the sign of the argument

The usual arithmetic operators are available. The result is determined
according to the following rules:

   * In the case of `-', `+', and `*', the result is calculated with
     *Note `BIGINT': numeric-types.  (64-bit) precision if both
     arguments are integers.

   * If one of the arguments is an unsigned integer, and the other
     argument is also an integer, the result is an unsigned integer.

   * If any of the operands of a `+', `-', `/', `*', `%' is a real or
     string value, then the precision of the result is the precision of
     the argument with the maximum precision.

   * In division performed with `/', the scale of the result when using
     two exact values is the scale of the first argument plus the value
     of the `div_precision_increment' system variable (which is 4 by
     default). For example, the result of the expression `5.05 / 0.014'
     has a scale of six decimal places (`360.714286').

These rules are applied for each operation, such that nested
calculations imply the precision of each component. Hence, `(14620 /
9432456) / (24250 / 9432456)', would resolve first to `(0.0014) /
(0.0026)', with the final result having 8 decimal places (`0.60288653').

Because of these rules and the way they are applied, care should be
taken to ensure that components and sub-components of a calculation use
the appropriate level of precision. See *Note cast-functions::.

   *  `+'

     Addition:

          mysql> SELECT 3+5;
                  -> 8

   *  `-'

     Subtraction:

          mysql> SELECT 3-5;
                  -> -2

   *  `-'

     Unary minus. This operator changes the sign of the argument.

          mysql> SELECT - 2;
                  -> -2

     *Note*:

     If this operator is used with a *Note `BIGINT': numeric-types, the
     return value is also a *Note `BIGINT': numeric-types. This means
     that you should avoid using `-' on integers that may have the
     value of -2^63.

   *  `*'

     Multiplication:

          mysql> SELECT 3*5;
                  -> 15
          mysql> SELECT 18014398509481984*18014398509481984.0;
                  -> 324518553658426726783156020576256.0
          mysql> SELECT 18014398509481984*18014398509481984;
                  -> 0

     The result of the last expression is incorrect because the result
     of the integer multiplication exceeds the 64-bit range of *Note
     `BIGINT': numeric-types. calculations.  (See *Note
     numeric-types::.)

   *  `/'

     Division:

          mysql> SELECT 3/5;
                  -> 0.60

     Division by zero produces a `NULL' result:

          mysql> SELECT 102/(1-1);
                  -> NULL

     A division is calculated with *Note `BIGINT': numeric-types.
     arithmetic only if performed in a context where its result is
     converted to an integer.

   *  `DIV'

     Integer division. Similar to `FLOOR()', but is safe with *Note
     `BIGINT': numeric-types. values.

     As of MySQL 6.0.10, if either operand has a non-integer type, the
     operands are converted to *Note `DECIMAL': numeric-types. and
     divided using *Note `DECIMAL': numeric-types. arithmetic before
     converting the result to *Note `BIGINT': numeric-types. If the
     result exceeds `BIGINT' range, an error occurs. Before MySQL
     6.0.10, incorrect results may occur for non-integer operands that
     exceed *Note `BIGINT': numeric-types.  range.

          mysql> SELECT 5 DIV 2;
                  -> 2

   *  `N % M'

     Modulo operation. Returns the remainder of N divided by M. For
     more information, see the description for the `MOD()' function in
     *Note mathematical-functions::.


File: manual.info,  Node: mathematical-functions,  Prev: arithmetic-functions,  Up: numeric-functions

11.5.2 Mathematical Functions
-----------------------------

*Name*                        *Description*
`ABS()'                       Return the absolute value
`ACOS()'                      Return the arc cosine
`ASIN()'                      Return the arc sine
`ATAN2()', `ATAN()'           Return the arc tangent of the two arguments
`ATAN()'                      Return the arc tangent
`CEIL()'                      Return the smallest integer value not less
                              than  the argument
`CEILING()'                   Return the smallest integer value not less
                              than  the argument
`CONV()'                      Convert numbers between different number
                              bases
`COS()'                       Return the cosine
`COT()'                       Return the cotangent
`CRC32()'(v4.1.0)             Compute a cyclic redundancy check value
`DEGREES()'                   Convert radians to degrees
`EXP()'                       Raise to the power of
`FLOOR()'                     Return the largest integer value not
                              greater than  the argument
`LN()'                        Return the natural logarithm of the
                              argument
`LOG10()'                     Return the base-10 logarithm of the
                              argument
`LOG2()'                      Return the base-2 logarithm of the argument
`LOG()'                       Return the natural logarithm of the first
                              argument
`MOD()'                       Return the remainder
`OCT()'                       Return an octal representation of a
                              decimal  number
`PI()'                        Return the value of pi
`POW()'                       Return the argument raised to the
                              specified power
`POWER()'                     Return the argument raised to the
                              specified power
`RADIANS()'                   Return argument converted to radians
`RAND()'                      Return a random floating-point value
`ROUND()'                     Round the argument
`SIGN()'                      Return the sign of the argument
`SIN()'                       Return the sine of the argument
`SQRT()'                      Return the square root of the argument
`TAN()'                       Return the tangent of the argument
`TRUNCATE()'                  Truncate to specified number of decimal
                              places

All mathematical functions return `NULL' in the event of an error.

   *  `ABS(X)'

     Returns the absolute value of X.

          mysql> SELECT ABS(2);
                  -> 2
          mysql> SELECT ABS(-32);
                  -> 32

     This function is safe to use with *Note `BIGINT': numeric-types.
     values.

   *  `ACOS(X)'

     Returns the arc cosine of X, that is, the value whose cosine is X.
     Returns `NULL' if X is not in the range `-1' to `1'.

          mysql> SELECT ACOS(1);
                  -> 0
          mysql> SELECT ACOS(1.0001);
                  -> NULL
          mysql> SELECT ACOS(0);
                  -> 1.5707963267949

   *  `ASIN(X)'

     Returns the arc sine of X, that is, the value whose sine is X.
     Returns `NULL' if X is not in the range `-1' to `1'.

          mysql> SELECT ASIN(0.2);
                  -> 0.20135792079033
          mysql> SELECT ASIN('foo');

          +-------------+
          | ASIN('foo') |
          +-------------+
          |           0 |
          +-------------+
          1 row in set, 1 warning (0.00 sec)

          mysql> SHOW WARNINGS;
          +---------+------+-----------------------------------------+
          | Level   | Code | Message                                 |
          +---------+------+-----------------------------------------+
          | Warning | 1292 | Truncated incorrect DOUBLE value: 'foo' |
          +---------+------+-----------------------------------------+

   *  `ATAN(X)'

     Returns the arc tangent of X, that is, the value whose tangent is
     X.

          mysql> SELECT ATAN(2);
                  -> 1.1071487177941
          mysql> SELECT ATAN(-2);
                  -> -1.1071487177941

   *  `ATAN(Y,X)', `ATAN2(Y,X)'

     Returns the arc tangent of the two variables X and Y. It is
     similar to calculating the arc tangent of `Y / X', except that the
     signs of both arguments are used to determine the quadrant of the
     result.

          mysql> SELECT ATAN(-2,2);
                  -> -0.78539816339745
          mysql> SELECT ATAN2(PI(),0);
                  -> 1.5707963267949

   *  `CEIL(X)'

     `CEIL()' is a synonym for `CEILING()'.

   *  `CEILING(X)'

     Returns the smallest integer value not less than X.

          mysql> SELECT CEILING(1.23);
                  -> 2
          mysql> SELECT CEILING(-1.23);
                  -> -1

     For exact-value numeric arguments, the return value has an
     exact-value numeric type. For string or floating-point arguments,
     the return value has a floating-point type.

   *  `CONV(N,FROM_BASE,TO_BASE)'

     Converts numbers between different number bases. Returns a string
     representation of the number N, converted from base FROM_BASE to
     base TO_BASE. Returns `NULL' if any argument is `NULL'. The
     argument N is interpreted as an integer, but may be specified as
     an integer or a string. The minimum base is `2' and the maximum
     base is `36'. If TO_BASE is a negative number, N is regarded as a
     signed number. Otherwise, N is treated as unsigned.  `CONV()'
     works with 64-bit precision.

          mysql> SELECT CONV('a',16,2);
                  -> '1010'
          mysql> SELECT CONV('6E',18,8);
                  -> '172'
          mysql> SELECT CONV(-17,10,-18);
                  -> '-H'
          mysql> SELECT CONV(10+'10'+'10'+0xa,10,10);
                  -> '40'

   *  `COS(X)'

     Returns the cosine of X, where X is given in radians.

          mysql> SELECT COS(PI());
                  -> -1

   *  `COT(X)'

     Returns the cotangent of X.

          mysql> SELECT COT(12);
                  -> -1.5726734063977
          mysql> SELECT COT(0);
                  -> NULL

   *  `CRC32(EXPR)'

     Computes a cyclic redundancy check value and returns a 32-bit
     unsigned value. The result is `NULL' if the argument is `NULL'.
     The argument is expected to be a string and (if possible) is
     treated as one if it is not.

          mysql> SELECT CRC32('MySQL');
                  -> 3259397556
          mysql> SELECT CRC32('mysql');
                  -> 2501908538

   *  `DEGREES(X)'

     Returns the argument X, converted from radians to degrees.

          mysql> SELECT DEGREES(PI());
                  -> 180
          mysql> SELECT DEGREES(PI() / 2);
                  -> 90

   *  `EXP(X)'

     Returns the value of _e_ (the base of natural logarithms) raised
     to the power of X. The inverse of this function is `LOG()' (using
     a single argument only) or `LN()'.

          mysql> SELECT EXP(2);
                  -> 7.3890560989307
          mysql> SELECT EXP(-2);
                  -> 0.13533528323661
          mysql> SELECT EXP(0);
                  -> 1

   *  `FLOOR(X)'

     Returns the largest integer value not greater than X.

          mysql> SELECT FLOOR(1.23);
                  -> 1
          mysql> SELECT FLOOR(-1.23);
                  -> -2

     For exact-value numeric arguments, the return value has an
     exact-value numeric type. For string or floating-point arguments,
     the return value has a floating-point type.

   * `FORMAT(X,D)'

     Formats the number X to a format like `'#,###,###.##'', rounded to
     D decimal places, and returns the result as a string. For details,
     see *Note string-functions::.

   * `HEX(N_or_S)'

     This function can be used to obtain a hexadecimal representation
     of a decimal number or a string; the manner in which it does so
     varies according to the argument's type. See this function's
     description in *Note string-functions::, for details.

   *  `LN(X)'

     Returns the natural logarithm of X; that is, the base-_e_
     logarithm of X. If X is less than or equal to 0, then `NULL' is
     returned.

          mysql> SELECT LN(2);
                  -> 0.69314718055995
          mysql> SELECT LN(-2);
                  -> NULL

     This function is synonymous with `LOG(X)'.  The inverse of this
     function is the `EXP()' function.

   *  `LOG(X)', `LOG(B,X)'

     If called with one parameter, this function returns the natural
     logarithm of X. If X is less than or equal to 0, then `NULL' is
     returned.

     The inverse of this function (when called with a single argument)
     is the `EXP()' function.

          mysql> SELECT LOG(2);
                  -> 0.69314718055995
          mysql> SELECT LOG(-2);
                  -> NULL

     If called with two parameters, this function returns the logarithm
     of X to the base B. If X is less than or equal to 0, or if B is
     less than or equal to 1, then `NULL' is returned.

          mysql> SELECT LOG(2,65536);
                  -> 16
          mysql> SELECT LOG(10,100);
                  -> 2
          mysql> SELECT LOG(1,100);
                  -> NULL

     `LOG(B,X)' is equivalent to `LOG(X) / LOG(B)'.

   *  `LOG2(X)'

     Returns the base-2 logarithm of `X'.

          mysql> SELECT LOG2(65536);
                  -> 16
          mysql> SELECT LOG2(-100);
                  -> NULL

     `LOG2()' is useful for finding out how many bits a number requires
     for storage. This function is equivalent to the expression `LOG(X)
     / LOG(2)'.

   *  `LOG10(X)'

     Returns the base-10 logarithm of X.

          mysql> SELECT LOG10(2);
                  -> 0.30102999566398
          mysql> SELECT LOG10(100);
                  -> 2
          mysql> SELECT LOG10(-100);
                  -> NULL

     `LOG10(X)' is equivalent to `LOG(10,X)'.

   *  `MOD(N,M)', `N % M', `N MOD M'

     Modulo operation. Returns the remainder of N divided by M.

          mysql> SELECT MOD(234, 10);
                  -> 4
          mysql> SELECT 253 % 7;
                  -> 1
          mysql> SELECT MOD(29,9);
                  -> 2
          mysql> SELECT 29 MOD 9;
                  -> 2

     This function is safe to use with *Note `BIGINT': numeric-types.
     values.

     `MOD()' also works on values that have a fractional part and
     returns the exact remainder after division:

          mysql> SELECT MOD(34.5,3);
                  -> 1.5

     `MOD(N,0)' returns `NULL'.

   *  `OCT(N)'

     Returns a string representation of the octal value of N, where N
     is a longlong (*Note `BIGINT': numeric-types.) number. This is
     equivalent to `CONV(N,10,8)'.  Returns `NULL' if N is `NULL'.

          mysql> SELECT OCT(12);
                  -> '14'

   *  `PI()'

     Returns the value of π (pi). The default number of decimal places
     displayed is seven, but MySQL uses the full double-precision value
     internally.

          mysql> SELECT PI();
                  -> 3.141593
          mysql> SELECT PI()+0.000000000000000000;
                  -> 3.141592653589793116

   *  `POW(X,Y)'

     Returns the value of X raised to the power of Y.

          mysql> SELECT POW(2,2);
                  -> 4
          mysql> SELECT POW(2,-2);
                  -> 0.25

   *  `POWER(X,Y)'

     This is a synonym for `POW()'.

   *  `RADIANS(X)'

     Returns the argument X, converted from degrees to radians. (Note
     that π radians equals 180 degrees.)

          mysql> SELECT RADIANS(90);
                  -> 1.5707963267949

   *  `RAND()', `RAND(N)'

     Returns a random floating-point value V in the range `0' <= V <
     `1.0'. If a constant integer argument N is specified, it is used
     as the seed value, which produces a repeatable sequence of column
     values. In the following example, note that the sequences of
     values produced by `RAND(3)' is the same both places where it
     occurs.

          mysql> CREATE TABLE t (i INT);
          Query OK, 0 rows affected (0.42 sec)

          mysql> INSERT INTO t VALUES(1),(2),(3);
          Query OK, 3 rows affected (0.00 sec)
          Records: 3  Duplicates: 0  Warnings: 0

          mysql> SELECT i, RAND() FROM t;
          +------+------------------+
          | i    | RAND()           |
          +------+------------------+
          |    1 | 0.61914388706828 |
          |    2 | 0.93845168309142 |
          |    3 | 0.83482678498591 |
          +------+------------------+
          3 rows in set (0.00 sec)

          mysql> SELECT i, RAND(3) FROM t;
          +------+------------------+
          | i    | RAND(3)          |
          +------+------------------+
          |    1 | 0.90576975597606 |
          |    2 | 0.37307905813035 |
          |    3 | 0.14808605345719 |
          +------+------------------+
          3 rows in set (0.00 sec)

          mysql> SELECT i, RAND() FROM t;
          +------+------------------+
          | i    | RAND()           |
          +------+------------------+
          |    1 | 0.35877890638893 |
          |    2 | 0.28941420772058 |
          |    3 | 0.37073435016976 |
          +------+------------------+
          3 rows in set (0.00 sec)

          mysql> SELECT i, RAND(3) FROM t;
          +------+------------------+
          | i    | RAND(3)          |
          +------+------------------+
          |    1 | 0.90576975597606 |
          |    2 | 0.37307905813035 |
          |    3 | 0.14808605345719 |
          +------+------------------+
          3 rows in set (0.01 sec)

     With a constant initializer, the seed is initialized once when the
     statement is compiled, prior to execution. If a non-constant
     initializer (such as a column name) is used as the argument, the
     seed is initialized with the value for each invocation of `RAND()'.
     (One implication of this is that for equal argument values,
     `RAND()' will return the same value each time.)

     To obtain a random integer R in the range I <= R < J, use the
     expression `FLOOR(I + RAND() * (J - I))'. For example, to obtain a
     random integer in the range the range `7' <= R < `12', you could
     use the following statement:

          SELECT FLOOR(7 + (RAND() * 5));

     `RAND()' in a `WHERE' clause is re-evaluated every time the
     `WHERE' is executed.

     You cannot use a column with `RAND()' values in an `ORDER BY'
     clause, because `ORDER BY' would evaluate the column multiple
     times.  However, you can retrieve rows in random order like this:

          mysql> SELECT * FROM TBL_NAME ORDER BY RAND();

     `ORDER BY RAND()' combined with `LIMIT' is useful for selecting a
     random sample from a set of rows:

          mysql> SELECT * FROM table1, table2 WHERE a=b AND c<d -> ORDER BY RAND() LIMIT 1000;

     `RAND()' is not meant to be a perfect random generator, but
     instead is a fast way to generate _ad hoc_ random numbers which is
     portable between platforms for the same MySQL version.

   *  `ROUND(X)', `ROUND(X,D)'

     Rounds the argument X to D decimal places. The rounding algorithm
     depends on the data type of X. D defaults to 0 if not specified. D
     can be negative to cause D digits left of the decimal point of the
     value X to become zero.

          mysql> SELECT ROUND(-1.23);
                  -> -1
          mysql> SELECT ROUND(-1.58);
                  -> -2
          mysql> SELECT ROUND(1.58);
                  -> 2
          mysql> SELECT ROUND(1.298, 1);
                  -> 1.3
          mysql> SELECT ROUND(1.298, 0);
                  -> 1
          mysql> SELECT ROUND(23.298, -1);
                  -> 20

     The return type is the same type as that of the first argument
     (assuming that it is integer, double, or decimal).  This means
     that for an integer argument, the result is an integer (no decimal
     places):

          mysql> SELECT ROUND(150.000,2), ROUND(150,2);
          +------------------+--------------+
          | ROUND(150.000,2) | ROUND(150,2) |
          +------------------+--------------+
          |           150.00 |          150 |
          +------------------+--------------+

     `ROUND()' uses the following rules depending on the type of the
     first argument:

        * For exact-value numbers, `ROUND()' uses the `round half up'
          or `round toward nearest' rule: A value with a fractional
          part of .5 or greater is rounded up to the next integer if
          positive or down to the next integer if negative. (In other
          words, it is rounded away from zero.) A value with a
          fractional part less than .5 is rounded down to the next
          integer if positive or up to the next integer if negative.

        * For approximate-value numbers, the result depends on the C
          library. On many systems, this means that `ROUND()' uses the
          "round to nearest even" rule: A value with any fractional part
          is rounded to the nearest even integer.

     The following example shows how rounding differs for exact and
     approximate values:

          mysql> SELECT ROUND(2.5), ROUND(25E-1);
          +------------+--------------+
          | ROUND(2.5) | ROUND(25E-1) |
          +------------+--------------+
          | 3          |            2 |
          +------------+--------------+

     For more information, see *Note precision-math::.

   *  `SIGN(X)'

     Returns the sign of the argument as `-1', `0', or `1', depending on
     whether X is negative, zero, or positive.

          mysql> SELECT SIGN(-32);
                  -> -1
          mysql> SELECT SIGN(0);
                  -> 0
          mysql> SELECT SIGN(234);
                  -> 1

   *  `SIN(X)'

     Returns the sine of X, where X is given in radians.

          mysql> SELECT SIN(PI());
                  -> 1.2246063538224e-16
          mysql> SELECT ROUND(SIN(PI()));
                  -> 0

   *  `SQRT(X)'

     Returns the square root of a non-negative number X.

          mysql> SELECT SQRT(4);
                  -> 2
          mysql> SELECT SQRT(20);
                  -> 4.4721359549996
          mysql> SELECT SQRT(-16);
                  -> NULL

   *  `TAN(X)'

     Returns the tangent of X, where X is given in radians.

          mysql> SELECT TAN(PI());
                  -> -1.2246063538224e-16
          mysql> SELECT TAN(PI()+1);
                  -> 1.5574077246549

   *  `TRUNCATE(X,D)'

     Returns the number X, truncated to D decimal places. If D is `0',
     the result has no decimal point or fractional part.  D can be
     negative to cause D digits left of the decimal point of the value
     X to become zero.

          mysql> SELECT TRUNCATE(1.223,1);
                  -> 1.2
          mysql> SELECT TRUNCATE(1.999,1);
                  -> 1.9
          mysql> SELECT TRUNCATE(1.999,0);
                  -> 1
          mysql> SELECT TRUNCATE(-1.999,1);
                  -> -1.9
          mysql> SELECT TRUNCATE(122,-2);
                 -> 100
          mysql> SELECT TRUNCATE(10.28*100,0);
                 -> 1028

     All numbers are rounded toward zero.


File: manual.info,  Node: date-and-time-functions,  Next: mysql-calendar,  Prev: numeric-functions,  Up: functions

11.6 Date and Time Functions
============================

This section describes the functions that can be used to manipulate
temporal values. See *Note date-and-time-types::, for a description of
the range of values each date and time type has and the valid formats
in which values may be specified.

*Name*                        *Description*
`ADDDATE()'(v4.1.1)           Add dates
`ADDTIME()'(v4.1.1)           Add time
`CONVERT_TZ()'(v4.1.3)        Convert from one timezone to another
`CURDATE()'                   Return the current date
`CURRENT_DATE()',             Synonyms for CURDATE()
`CURRENT_DATE'                
`CURRENT_TIME()',             Synonyms for CURTIME()
`CURRENT_TIME'                
`CURRENT_TIMESTAMP()',        Synonyms for NOW()
`CURRENT_TIMESTAMP'           
`CURTIME()'                   Return the current time
`DATE_ADD()'                  Add two dates
`DATE_FORMAT()'               Format date as specified
`DATE_SUB()'                  Subtract two dates
`DATE()'(v4.1.1)              Extract the date part of a date or
                              datetime expression
`DATEDIFF()'(v4.1.1)          Subtract two dates
`DAY()'(v4.1.1)               Synonym for DAYOFMONTH()
`DAYNAME()'(v4.1.21)          Return the name of the weekday
`DAYOFMONTH()'                Return the day of the month (0-31)
`DAYOFWEEK()'                 Return the weekday index of the argument
`DAYOFYEAR()'                 Return the day of the year (1-366)
`EXTRACT'                     Extract part of a date
`FROM_DAYS()'                 Convert a day number to a date
`FROM_UNIXTIME()'             Format UNIX timestamp as a date
`GET_FORMAT()'(v4.1.1)        Return a date format string
`HOUR()'                      Extract the hour
`LAST_DAY'(v4.1.1)            Return the last day of the month for the
                              argument
`LOCALTIME()', `LOCALTIME'    Synonym for NOW()
`LOCALTIMESTAMP',             Synonym for NOW()
`LOCALTIMESTAMP()'(v4.0.6)    
`MAKEDATE()'(v4.1.1)          Create a date from the year and day of year
`MAKETIME'(v4.1.1)            MAKETIME()
`MICROSECOND()'(v4.1.1)       Return the microseconds from argument
`MINUTE()'                    Return the minute from the argument
`MONTH()'                     Return the month from the date passed
`MONTHNAME()'(v4.1.21)        Return the name of the month
`NOW()'                       Return the current date and time
`PERIOD_ADD()'                Add a period to a year-month
`PERIOD_DIFF()'               Return the number of months between periods
`QUARTER()'                   Return the quarter from a date argument
`SEC_TO_TIME()'               Converts seconds to 'HH:MM:SS' format
`SECOND()'                    Return the second (0-59)
`STR_TO_DATE()'(v4.1.1)       Convert a string to a date
`SUBDATE()'                   A synonym for DATE_SUB() when invoked with
                              three arguments
`SUBTIME()'(v4.1.1)           Subtract times
`SYSDATE()'                   Return the time at which the function
                              executes
`TIME_FORMAT()'               Format as time
`TIME_TO_SEC()'               Return the argument converted to seconds
`TIME()'(v4.1.1)              Extract the time portion of the expression
                              passed
`TIMEDIFF()'(v4.1.1)          Subtract time
`TIMESTAMP()'(v4.1.1)         With a single argument, this function
                              returns the date or  datetime expression;
                              with two arguments, the sum of the
                              arguments
`TIMESTAMPADD()'(v5.0.0)      Add an interval to a datetime expression
`TIMESTAMPDIFF()'(v5.0.0)     Subtract an interval from a datetime
                              expression
`TO_DAYS()'                   Return the date argument converted to days
`UNIX_TIMESTAMP()'            Return a UNIX timestamp
`UTC_DATE()'(v4.1.1)          Return the current UTC date
`UTC_TIME()'(v4.1.1)          Return the current UTC time
`UTC_TIMESTAMP()'(v4.1.1)     Return the current UTC date and time
`WEEK()'                      Return the week number
`WEEKDAY()'                   Return the weekday index
`WEEKOFYEAR()'(v4.1.1)        Return the calendar week of the date (0-53)
`YEAR()'                      Return the year
`YEARWEEK()'                  Return the year and week

Here is an example that uses date functions. The following query
selects all rows with a DATE_COL value from within the last 30 days:

     mysql> SELECT SOMETHING FROM TBL_NAME
         -> WHERE DATE_SUB(CURDATE(),INTERVAL 30 DAY) <= DATE_COL;

The query also selects rows with dates that lie in the future.

Functions that expect date values usually accept datetime values and
ignore the time part. Functions that expect time values usually accept
datetime values and ignore the date part.

Functions that return the current date or time each are evaluated only
once per query at the start of query execution. This means that
multiple references to a function such as `NOW()' within a single query
always produce the same result. (For our purposes, a single query also
includes a call to a stored program (stored routine, trigger, or event)
and all sub-programs called by that program.) This principle also
applies to `CURDATE()', `CURTIME()', `UTC_DATE()', `UTC_TIME()',
`UTC_TIMESTAMP()', and to any of their synonyms.

The `CURRENT_TIMESTAMP()', `CURRENT_TIME()', `CURRENT_DATE()', and
`FROM_UNIXTIME()' functions return values in the connection's current
time zone, which is available as the value of the `time_zone' system
variable. In addition, `UNIX_TIMESTAMP()' assumes that its argument is
a datetime value in the current time zone. See *Note
time-zone-support::.

Some date functions can be used with `zero' dates or incomplete dates
such as `'2001-11-00'', whereas others cannot. Functions that extract
parts of dates typically work with incomplete dates and thus can return
0 when you might otherwise expect a non-zero value. For example:

     mysql> SELECT DAYOFMONTH('2001-11-00'), MONTH('2005-00-00');
             -> 0, 0

Other functions expect complete dates and return `NULL' for incomplete
dates. These include functions that perform date arithmetic or that map
parts of dates to names. For example:

     mysql> SELECT DATE_ADD('2006-05-00',INTERVAL 1 DAY);
             -> NULL
     mysql> SELECT DAYNAME('2006-05-00');
             -> NULL

   *  `ADDDATE(DATE,INTERVAL EXPR UNIT)', `ADDDATE(EXPR,DAYS)'

     When invoked with the `INTERVAL' form of the second argument,
     `ADDDATE()' is a synonym for `DATE_ADD()'. The related function
     `SUBDATE()' is a synonym for `DATE_SUB()'. For information on the
     `INTERVAL' UNIT argument, see the discussion for `DATE_ADD()'.

          mysql> SELECT DATE_ADD('2008-01-02', INTERVAL 31 DAY);
                  -> '2008-02-02'
          mysql> SELECT ADDDATE('2008-01-02', INTERVAL 31 DAY);
                  -> '2008-02-02'

     When invoked with the DAYS form of the second argument, MySQL
     treats it as an integer number of days to be added to EXPR.

          mysql> SELECT ADDDATE('2008-01-02', 31);
                  -> '2008-02-02'

   *  `ADDTIME(EXPR1,EXPR2)'

     `ADDTIME()' adds EXPR2 to EXPR1 and returns the result.  EXPR1 is
     a time or datetime expression, and EXPR2 is a time expression.

          mysql> SELECT ADDTIME('2007-12-31 23:59:59.999999', '1 1:1:1.000002');
                  -> '2008-01-02 01:01:01.000001'
          mysql> SELECT ADDTIME('01:00:00.999999', '02:00:00.999998');
                  -> '03:00:01.999997'

   *  `CONVERT_TZ(DT,FROM_TZ,TO_TZ)'

     `CONVERT_TZ()' converts a datetime value DT from the time zone
     given by FROM_TZ to the time zone given by TO_TZ and returns the
     resulting value. Time zones are specified as described in *Note
     time-zone-support::. This function returns `NULL' if the arguments
     are invalid.

     If the value falls out of the supported range of the *Note
     `TIMESTAMP': datetime. type when converted from FROM_TZ to UTC, no
     conversion occurs. The *Note `TIMESTAMP': datetime. range is
     described in *Note date-and-time-type-overview::.

          mysql> SELECT CONVERT_TZ('2004-01-01 12:00:00','GMT','MET');
                  -> '2004-01-01 13:00:00'
          mysql> SELECT CONVERT_TZ('2004-01-01 12:00:00','+00:00','+10:00');
                  -> '2004-01-01 22:00:00'

     *Note*:

     To use named time zones such as `'MET'' or `'Europe/Moscow'', the
     time zone tables must be properly set up. See *Note
     time-zone-support::, for instructions.

   *  `CURDATE()'

     Returns the current date as a value in `'YYYY-MM-DD'' or `YYYYMMDD'
     format, depending on whether the function is used in a string or
     numeric context.

          mysql> SELECT CURDATE();
                  -> '2008-06-13'
          mysql> SELECT CURDATE() + 0;
                  -> 20080613

   *  `CURRENT_DATE', `CURRENT_DATE()'

     `CURRENT_DATE' and `CURRENT_DATE()' are synonyms for `CURDATE()'.

   *  `CURTIME()'

     Returns the current time as a value in `'HH:MM:SS'' or
     `HHMMSS.uuuuuu' format, depending on whether the function is used
     in a string or numeric context. The value is expressed in the
     current time zone.

          mysql> SELECT CURTIME();
                  -> '23:50:26'
          mysql> SELECT CURTIME() + 0;
                  -> 235026.000000

   *  `CURRENT_TIME', `CURRENT_TIME()'

     `CURRENT_TIME' and `CURRENT_TIME()' are synonyms for `CURTIME()'.

   *  `CURRENT_TIMESTAMP', `CURRENT_TIMESTAMP()'

     `CURRENT_TIMESTAMP' and `CURRENT_TIMESTAMP()' are synonyms for
     `NOW()'.

   *  `DATE(EXPR)'

     Extracts the date part of the date or datetime expression EXPR.

          mysql> SELECT DATE('2003-12-31 01:02:03');
                  -> '2003-12-31'

   *  `DATEDIFF(EXPR1,EXPR2)'

     `DATEDIFF()' returns EXPR1 - EXPR2 expressed as a value in days
     from one date to the other. EXPR1 and EXPR2 are date or
     date-and-time expressions. Only the date parts of the values are
     used in the calculation.

          mysql> SELECT DATEDIFF('2007-12-31 23:59:59','2007-12-30');
                  -> 1
          mysql> SELECT DATEDIFF('2010-11-30 23:59:59','2010-12-31');
                  -> -31

   *  `DATE_ADD(DATE,INTERVAL EXPR UNIT)', `DATE_SUB(DATE,INTERVAL EXPR
     UNIT)'

     These functions perform date arithmetic. The DATE argument
     specifies the starting date or datetime value.  EXPR is an
     expression specifying the interval value to be added or subtracted
     from the starting date. EXPR is a string; it may start with a
     ``-'' for negative intervals. UNIT is a keyword indicating the
     units in which the expression should be interpreted.

     The `INTERVAL' keyword and the UNIT specifier are not case
     sensitive.

     The following table shows the expected form of the EXPR argument
     for each UNIT value.

     UNIT *Value*                       *Expected* EXPR *Format*
     `MICROSECOND'                      `MICROSECONDS'
     `SECOND'                           `SECONDS'
     `MINUTE'                           `MINUTES'
     `HOUR'                             `HOURS'
     `DAY'                              `DAYS'
     `WEEK'                             `WEEKS'
     `MONTH'                            `MONTHS'
     `QUARTER'                          `QUARTERS'
     `YEAR'                             `YEARS'
     `SECOND_MICROSECOND'               `'SECONDS.MICROSECONDS''
     `MINUTE_MICROSECOND'               `'MINUTES:SECONDS.MICROSECONDS''
     `MINUTE_SECOND'                    `'MINUTES:SECONDS''
     `HOUR_MICROSECOND'                 `'HOURS:MINUTES:SECONDS.MICROSECONDS''
     `HOUR_SECOND'                      `'HOURS:MINUTES:SECONDS''
     `HOUR_MINUTE'                      `'HOURS:MINUTES''
     `DAY_MICROSECOND'                  `'DAYS
                                        HOURS:MINUTES:SECONDS.MICROSECONDS''
     `DAY_SECOND'                       `'DAYS HOURS:MINUTES:SECONDS''
     `DAY_MINUTE'                       `'DAYS HOURS:MINUTES''
     `DAY_HOUR'                         `'DAYS HOURS''
     `YEAR_MONTH'                       `'YEARS-MONTHS''

     The return value depends on the arguments:

        * *Note `DATETIME': datetime. if the first argument is a *Note
          `DATETIME': datetime. (or *Note `TIMESTAMP': datetime.)
          value, or if the first argument is a *Note `DATE': datetime.
          and the UNIT value uses `HOURS', `MINUTES', or `SECONDS'.

        * String otherwise.

     To ensure that the result is *Note `DATETIME': datetime, you can
     use `CAST()' to convert the first argument to *Note `DATETIME':
     datetime.

     MySQL allows any punctuation delimiter in the EXPR format. Those
     shown in the table are the suggested delimiters. If the DATE
     argument is a *Note `DATE': datetime. value and your calculations
     involve only `YEAR', `MONTH', and `DAY' parts (that is, no time
     parts), the result is a *Note `DATE': datetime. value. Otherwise,
     the result is a *Note `DATETIME': datetime. value.

     Date arithmetic also can be performed using `INTERVAL' together
     with the `+' or `-' operator:

          `date' + INTERVAL EXPR UNIT
          `date' - INTERVAL EXPR UNIT

     `INTERVAL EXPR UNIT' is allowed on either side of the `+' operator
     if the expression on the other side is a date or datetime value.
     For the `-' operator, `INTERVAL EXPR UNIT' is allowed only on the
     right side, because it makes no sense to subtract a date or
     datetime value from an interval.

          mysql> SELECT '2008-12-31 23:59:59' + INTERVAL 1 SECOND;
                  -> '2009-01-01 00:00:00'
          mysql> SELECT INTERVAL 1 DAY + '2008-12-31';
                  -> '2009-01-01'
          mysql> SELECT '2005-01-01' - INTERVAL 1 SECOND;
                  -> '2004-12-31 23:59:59'
          mysql> SELECT DATE_ADD('2000-12-31 23:59:59',
              ->                 INTERVAL 1 SECOND);
                  -> '2001-01-01 00:00:00'
          mysql> SELECT DATE_ADD('2010-12-31 23:59:59',
              ->                 INTERVAL 1 DAY);
                  -> '2011-01-01 23:59:59'
          mysql> SELECT DATE_ADD('2100-12-31 23:59:59',
              ->                 INTERVAL '1:1' MINUTE_SECOND);
                  -> '2101-01-01 00:01:00'
          mysql> SELECT DATE_SUB('2005-01-01 00:00:00',
              ->                 INTERVAL '1 1:1:1' DAY_SECOND);
                  -> '2004-12-30 22:58:59'
          mysql> SELECT DATE_ADD('1900-01-01 00:00:00',
              ->                 INTERVAL '-1 10' DAY_HOUR);
                  -> '1899-12-30 14:00:00'
          mysql> SELECT DATE_SUB('1998-01-02', INTERVAL 31 DAY);
                  -> '1997-12-02'
          mysql> SELECT DATE_ADD('1992-12-31 23:59:59.000002',
              ->            INTERVAL '1.999999' SECOND_MICROSECOND);
                  -> '1993-01-01 00:00:01.000001'

     If you specify an interval value that is too short (does not
     include all the interval parts that would be expected from the
     UNIT keyword), MySQL assumes that you have left out the leftmost
     parts of the interval value.  For example, if you specify a UNIT
     of `DAY_SECOND', the value of EXPR is expected to have days,
     hours, minutes, and seconds parts. If you specify a value like
     `'1:10'', MySQL assumes that the days and hours parts are missing
     and the value represents minutes and seconds. In other words,
     `'1:10' DAY_SECOND' is interpreted in such a way that it is
     equivalent to `'1:10' MINUTE_SECOND'. This is analogous to the way
     that MySQL interprets *Note `TIME': time. values as representing
     elapsed time rather than as a time of day.

     Because EXPR is treated as a string, be careful if you specify a
     non-string value with `INTERVAL'. For example, with an interval
     specifier of `HOUR_MINUTE', `6/4' evaluates to `1.5000' and is
     treated as 1 hour, 5000 minutes:

          mysql> SELECT 6/4;
                  -> 1.5000
          mysql> SELECT DATE_ADD('2009-01-01', INTERVAL 6/4 HOUR_MINUTE);
                  -> '2009-01-04 12:20:00'

     To ensure interpretation of the interval value as you expect, a
     `CAST()' operation may be used.  To treat `6/4' as 1 hour, 5
     minutes, cast it to a *Note `DECIMAL': numeric-types. value with a
     single fractional digit:

          mysql> SELECT CAST(6/4 AS DECIMAL(3,1));
                  -> 1.5
          mysql> SELECT DATE_ADD('1970-01-01 12:00:00',
              ->                 INTERVAL CAST(6/4 AS DECIMAL(3,1)) HOUR_MINUTE);
                  -> '1970-01-01 13:05:00'

     If you add to or subtract from a date value something that
     contains a time part, the result is automatically converted to a
     datetime value:

          mysql> SELECT DATE_ADD('2013-01-01', INTERVAL 1 DAY);
                  -> '2013-01-02'
          mysql> SELECT DATE_ADD('2013-01-01', INTERVAL 1 HOUR);
                  -> '2013-01-01 01:00:00'

     If you add `MONTH', `YEAR_MONTH', or `YEAR' and the resulting date
     has a day that is larger than the maximum day for the new month,
     the day is adjusted to the maximum days in the new month:

          mysql> SELECT DATE_ADD('2009-01-30', INTERVAL 1 MONTH);
                  -> '2009-02-28'

     Date arithmetic operations require complete dates and do not work
     with incomplete dates such as `'2006-07-00'' or badly malformed
     dates:

          mysql> SELECT DATE_ADD('2006-07-00', INTERVAL 1 DAY);
                  -> NULL
          mysql> SELECT '2005-03-32' + INTERVAL 1 MONTH;
                  -> NULL

   *  `DATE_FORMAT(DATE,FORMAT)'

     Formats the DATE value according to the FORMAT string.

     The following specifiers may be used in the FORMAT string. The
     ``%'' character is required before format specifier characters.

     *Specifier*   *Description*
     `%a'          Abbreviated weekday name (`Sun'..`Sat')
     `%b'          Abbreviated month name (`Jan'..`Dec')
     `%c'          Month, numeric (`0'..`12')
     `%D'          Day of the month with English suffix (`0th',
                   `1st', `2nd', `3rd', ...)
     `%d'          Day of the month, numeric (`00'..`31')
     `%e'          Day of the month, numeric (`0'..`31')
     `%f'          Microseconds (`000000'..`999999')
     `%H'          Hour (`00'..`23')
     `%h'          Hour (`01'..`12')
     `%I'          Hour (`01'..`12')
     `%i'          Minutes, numeric (`00'..`59')
     `%j'          Day of year (`001'..`366')
     `%k'          Hour (`0'..`23')
     `%l'          Hour (`1'..`12')
     `%M'          Month name (`January'..`December')
     `%m'          Month, numeric (`00'..`12')
     `%p'          `AM' or `PM'
     `%r'          Time, 12-hour (`hh:mm:ss' followed by `AM' or
                   `PM')
     `%S'          Seconds (`00'..`59')
     `%s'          Seconds (`00'..`59')
     `%T'          Time, 24-hour (`hh:mm:ss')
     `%U'          Week (`00'..`53'), where Sunday is the first
                   day of the week
     `%u'          Week (`00'..`53'), where Monday is the first
                   day of the week
     `%V'          Week (`01'..`53'), where Sunday is the first
                   day of the week; used with `%X'
     `%v'          Week (`01'..`53'), where Monday is the first
                   day of the week; used with `%x'
     `%W'          Weekday name (`Sunday'..`Saturday')
     `%w'          Day of the week (`0'=Sunday..`6'=Saturday)
     `%X'          Year for the week where Sunday is the first
                   day of the week, numeric, four digits; used
                   with `%V'
     `%x'          Year for the week, where Monday is the first
                   day of the week, numeric, four digits; used
                   with `%v'
     `%Y'          Year, numeric, four digits
     `%y'          Year, numeric (two digits)
     `%%'          A literal ``%'' character
     `%X'          X, for any `X' not listed above

     Ranges for the month and day specifiers begin with zero due to the
     fact that MySQL allows the storing of incomplete dates such as
     `'2014-00-00''.

     The language used for day and month names and abbreviations is
     controlled by the value of the `lc_time_names' system variable
     (*Note locale-support::).

     The `DATE_FORMAT()' returns a string with a character set and
     collation given by `character_set_connection' and
     `collation_connection' so that it can return month and weekday
     names containing non-ASCII characters.

          mysql> SELECT DATE_FORMAT('2009-10-04 22:23:00', '%W %M %Y');
                  -> 'Sunday October 2009'
          mysql> SELECT DATE_FORMAT('2007-10-04 22:23:00', '%H:%i:%s');
                  -> '22:23:00'
          mysql> SELECT DATE_FORMAT('1900-10-04 22:23:00',
              ->                 '%D %y %a %d %m %b %j');
                  -> '4th 00 Thu 04 10 Oct 277'
          mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00',
              ->                 '%H %k %I %r %T %S %w');
                  -> '22 22 10 10:23:00 PM 22:23:00 00 6'
          mysql> SELECT DATE_FORMAT('1999-01-01', '%X %V');
                  -> '1998 52'
          mysql> SELECT DATE_FORMAT('2006-06-00', '%d');
                  -> '00'

   *  `DATE_SUB(DATE,INTERVAL EXPR UNIT)'

     See the description for `DATE_ADD()'.

   *  `DAY(DATE)'

     `DAY()' is a synonym for `DAYOFMONTH()'.

   *  `DAYNAME(DATE)'

     Returns the name of the weekday for DATE. The language used for the
     name is controlled by the value of the `lc_time_names' system
     variable (*Note locale-support::).

          mysql> SELECT DAYNAME('2007-02-03');
                  -> 'Saturday'

   *  `DAYOFMONTH(DATE)'

     Returns the day of the month for DATE, in the range `1' to `31', or
     `0' for dates such as `'0000-00-00'' or `'2008-00-00'' that have a
     zero day part.

          mysql> SELECT DAYOFMONTH('2007-02-03');
                  -> 3

   *  `DAYOFWEEK(DATE)'

     Returns the weekday index for DATE (`1' = Sunday, `2' = Monday,
     ..., `7' = Saturday). These index values correspond to the ODBC
     standard.

          mysql> SELECT DAYOFWEEK('2007-02-03');
                  -> 7

   *  `DAYOFYEAR(DATE)'

     Returns the day of the year for DATE, in the range `1' to `366'.

          mysql> SELECT DAYOFYEAR('2007-02-03');
                  -> 34

   *  `EXTRACT(UNIT FROM DATE)'

     The `EXTRACT()' function uses the same kinds of unit specifiers as
     `DATE_ADD()' or `DATE_SUB()', but extracts parts from the date
     rather than performing date arithmetic.

          mysql> SELECT EXTRACT(YEAR FROM '2009-07-02');
                 -> 2009
          mysql> SELECT EXTRACT(YEAR_MONTH FROM '2009-07-02 01:02:03');
                 -> 200907
          mysql> SELECT EXTRACT(DAY_MINUTE FROM '2009-07-02 01:02:03');
                 -> 20102
          mysql> SELECT EXTRACT(MICROSECOND
              ->                FROM '2003-01-02 10:30:00.000123');
                  -> 123

   *  `FROM_DAYS(N)'

     Given a day number N, returns a *Note `DATE': datetime. value.

          mysql> SELECT FROM_DAYS(730669);
                  -> '2007-07-03'

     Use `FROM_DAYS()' with caution on old dates. It is not intended
     for use with values that precede the advent of the Gregorian
     calendar (1582). See *Note mysql-calendar::.

   *  `FROM_UNIXTIME(UNIX_TIMESTAMP)',
     `FROM_UNIXTIME(UNIX_TIMESTAMP,FORMAT)'

     Returns a representation of the UNIX_TIMESTAMP argument as a value
     in `'YYYY-MM-DD HH:MM:SS'' or `YYYYMMDDHHMMSS.uuuuuu' format,
     depending on whether the function is used in a string or numeric
     context.  The value is expressed in the current time zone.
     UNIX_TIMESTAMP is an internal timestamp value such as is produced
     by the `UNIX_TIMESTAMP()' function.

     If FORMAT is given, the result is formatted according to the FORMAT
     string, which is used the same way as listed in the entry for the
     `DATE_FORMAT()' function.

          mysql> SELECT FROM_UNIXTIME(1196440219);
                  -> '2007-11-30 10:30:19'
          mysql> SELECT FROM_UNIXTIME(1196440219) + 0;
                  -> 20071130103019.000000
          mysql> SELECT FROM_UNIXTIME(UNIX_TIMESTAMP(),
              ->                      '%Y %D %M %h:%i:%s %x');
                  -> '2007 30th November 10:30:59 2007'

     Note: If you use `UNIX_TIMESTAMP()' and `FROM_UNIXTIME()' to
     convert between *Note `TIMESTAMP': datetime. values and Unix
     timestamp values, the conversion is lossy because the mapping is
     not one-to-one in both directions. For details, see the
     description of the `UNIX_TIMESTAMP()' function.

   *  `GET_FORMAT({DATE|TIME|DATETIME},
     {'EUR'|'USA'|'JIS'|'ISO'|'INTERNAL'})'

     Returns a format string. This function is useful in combination
     with the `DATE_FORMAT()' and the `STR_TO_DATE()' functions.

     The possible values for the first and second arguments result in
     several possible format strings (for the specifiers used, see the
     table in the `DATE_FORMAT()' function description). ISO format
     refers to ISO 9075, not ISO 8601.

     *Function Call*                          *Result*
     `GET_FORMAT(DATE,'USA')'                 `'%m.%d.%Y''
     `GET_FORMAT(DATE,'JIS')'                 `'%Y-%m-%d''
     `GET_FORMAT(DATE,'ISO')'                 `'%Y-%m-%d''
     `GET_FORMAT(DATE,'EUR')'                 `'%d.%m.%Y''
     `GET_FORMAT(DATE,'INTERNAL')'            `'%Y%m%d''
     `GET_FORMAT(DATETIME,'USA')'             `'%Y-%m-%d %H.%i.%s''
     `GET_FORMAT(DATETIME,'JIS')'             `'%Y-%m-%d %H:%i:%s''
     `GET_FORMAT(DATETIME,'ISO')'             `'%Y-%m-%d %H:%i:%s''
     `GET_FORMAT(DATETIME,'EUR')'             `'%Y-%m-%d %H.%i.%s''
     `GET_FORMAT(DATETIME,'INTERNAL')'        `'%Y%m%d%H%i%s''
     `GET_FORMAT(TIME,'USA')'                 `'%h:%i:%s %p''
     `GET_FORMAT(TIME,'JIS')'                 `'%H:%i:%s''
     `GET_FORMAT(TIME,'ISO')'                 `'%H:%i:%s''
     `GET_FORMAT(TIME,'EUR')'                 `'%H.%i.%s''
     `GET_FORMAT(TIME,'INTERNAL')'            `'%H%i%s''

     *Note `TIMESTAMP': datetime. can also be used as the first
     argument to `GET_FORMAT()', in which case the function returns the
     same values as for *Note `DATETIME': datetime.

          mysql> SELECT DATE_FORMAT('2003-10-03',GET_FORMAT(DATE,'EUR'));
                  -> '03.10.2003'
          mysql> SELECT STR_TO_DATE('10.31.2003',GET_FORMAT(DATE,'USA'));
                  -> '2003-10-31'

   *  `HOUR(TIME)'

     Returns the hour for TIME. The range of the return value is `0' to
     `23' for time-of-day values. However, the range of *Note `TIME':
     time. values actually is much larger, so `HOUR' can return values
     greater than `23'.

          mysql> SELECT HOUR('10:05:03');
                  -> 10
          mysql> SELECT HOUR('272:59:59');
                  -> 272

   *  `LAST_DAY(DATE)'

     Takes a date or datetime value and returns the corresponding value
     for the last day of the month. Returns `NULL' if the argument is
     invalid.

          mysql> SELECT LAST_DAY('2003-02-05');
                  -> '2003-02-28'
          mysql> SELECT LAST_DAY('2004-02-05');
                  -> '2004-02-29'
          mysql> SELECT LAST_DAY('2004-01-01 01:01:01');
                  -> '2004-01-31'
          mysql> SELECT LAST_DAY('2003-03-32');
                  -> NULL

   *  `LOCALTIME', `LOCALTIME()'

     `LOCALTIME' and `LOCALTIME()' are synonyms for `NOW()'.

   *  `LOCALTIMESTAMP', `LOCALTIMESTAMP()'

     `LOCALTIMESTAMP' and `LOCALTIMESTAMP()' are synonyms for `NOW()'.

   *  `MAKEDATE(YEAR,DAYOFYEAR)'

     Returns a date, given year and day-of-year values.  DAYOFYEAR must
     be greater than 0 or the result is `NULL'.

          mysql> SELECT MAKEDATE(2011,31), MAKEDATE(2011,32);
                  -> '2011-01-31', '2011-02-01'
          mysql> SELECT MAKEDATE(2011,365), MAKEDATE(2014,365);
                  -> '2011-12-31', '2014-12-31'
          mysql> SELECT MAKEDATE(2011,0);
                  -> NULL

   *  `MAKETIME(HOUR,MINUTE,SECOND)'

     Returns a time value calculated from the HOUR, MINUTE, and SECOND
     arguments.

          mysql> SELECT MAKETIME(12,15,30);
                  -> '12:15:30'

   *  `MICROSECOND(EXPR)'

     Returns the microseconds from the time or datetime expression EXPR
     as a number in the range from `0' to `999999'.

          mysql> SELECT MICROSECOND('12:00:00.123456');
                  -> 123456
          mysql> SELECT MICROSECOND('2009-12-31 23:59:59.000010');
                  -> 10

   *  `MINUTE(TIME)'

     Returns the minute for TIME, in the range `0' to `59'.

          mysql> SELECT MINUTE('2008-02-03 10:05:03');
                  -> 5

   *  `MONTH(DATE)'

     Returns the month for DATE, in the range `1' to `12' for January
     to December, or `0' for dates such as `'0000-00-00'' or
     `'2008-00-00'' that have a zero month part.

          mysql> SELECT MONTH('2008-02-03');
                  -> 2

   *  `MONTHNAME(DATE)'

     Returns the full name of the month for DATE. The language used for
     the name is controlled by the value of the `lc_time_names' system
     variable (*Note locale-support::).

          mysql> SELECT MONTHNAME('2008-02-03');
                  -> 'February'

   *  `NOW()'

     Returns the current date and time as a value in `'YYYY-MM-DD
     HH:MM:SS'' or `YYYYMMDDHHMMSS.uuuuuu' format, depending on whether
     the function is used in a string or numeric context.  The value is
     expressed in the current time zone.

          mysql> SELECT NOW();
                  -> '2007-12-15 23:50:26'
          mysql> SELECT NOW() + 0;
                  -> 20071215235026.000000

     `NOW()' returns a constant time that indicates the time at which
     the statement began to execute. (Within a stored routine or
     trigger, `NOW()' returns the time at which the routine or
     triggering statement began to execute.) This differs from the
     behavior for `SYSDATE()', which returns the exact time at which it
     executes.

          mysql> SELECT NOW(), SLEEP(2), NOW();
          +---------------------+----------+---------------------+
          | NOW()               | SLEEP(2) | NOW()               |
          +---------------------+----------+---------------------+
          | 2006-04-12 13:47:36 |        0 | 2006-04-12 13:47:36 |
          +---------------------+----------+---------------------+

          mysql> SELECT SYSDATE(), SLEEP(2), SYSDATE();
          +---------------------+----------+---------------------+
          | SYSDATE()           | SLEEP(2) | SYSDATE()           |
          +---------------------+----------+---------------------+
          | 2006-04-12 13:47:44 |        0 | 2006-04-12 13:47:46 |
          +---------------------+----------+---------------------+

     In addition, the `SET TIMESTAMP' statement affects the value
     returned by `NOW()' but not by `SYSDATE()'. This means that
     timestamp settings in the binary log have no effect on invocations
     of `SYSDATE()'.

     See the description for `SYSDATE()' for additional information
     about the differences between the two functions.

   *  `PERIOD_ADD(P,N)'

     Adds N months to period P (in the format `YYMM' or `YYYYMM').
     Returns a value in the format `YYYYMM'. Note that the period
     argument P is _not_ a date value.

          mysql> SELECT PERIOD_ADD(200801,2);
                  -> 200803

   *  `PERIOD_DIFF(P1,P2)'

     Returns the number of months between periods P1 and P2. P1 and P2
     should be in the format `YYMM' or `YYYYMM'. Note that the period
     arguments P1 and P2 are _not_ date values.

          mysql> SELECT PERIOD_DIFF(200802,200703);
                  -> 11

   *  `QUARTER(DATE)'

     Returns the quarter of the year for DATE, in the range `1' to `4'.

          mysql> SELECT QUARTER('2008-04-01');
                  -> 2

   *  `SECOND(TIME)'

     Returns the second for TIME, in the range `0' to `59'.

          mysql> SELECT SECOND('10:05:03');
                  -> 3

   *  `SEC_TO_TIME(SECONDS)'

     Returns the SECONDS argument, converted to hours, minutes, and
     seconds, as a *Note `TIME': time. value. The range of the result
     is constrained to that of the *Note `TIME': time. data type. A
     warning occurs if the argument corresponds to a value outside that
     range.

          mysql> SELECT SEC_TO_TIME(2378);
                  -> '00:39:38'
          mysql> SELECT SEC_TO_TIME(2378) + 0;
                  -> 3938

   *  `STR_TO_DATE(STR,FORMAT)'

     This is the inverse of the `DATE_FORMAT()' function. It takes a
     string STR and a format string FORMAT.  `STR_TO_DATE()' returns a
     *Note `DATETIME': datetime. value if the format string contains
     both date and time parts, or a *Note `DATE': datetime. or *Note
     `TIME': time. value if the string contains only date or time parts.

     The date, time, or datetime values contained in STR should be
     given in the format indicated by FORMAT. For the specifiers that
     can be used in FORMAT, see the `DATE_FORMAT()' function
     description. If STR contains an illegal date, time, or datetime
     value, `STR_TO_DATE()' returns `NULL'. An illegal value also
     produces a warning.

     Range checking on the parts of date values is as described in
     *Note datetime::. This means, for example, that `zero' dates or
     dates with part values of 0 are allowed unless the SQL mode is set
     to disallow such values.

          mysql> SELECT STR_TO_DATE('00/00/0000', '%m/%d/%Y');
                  -> '0000-00-00'
          mysql> SELECT STR_TO_DATE('04/31/2004', '%m/%d/%Y');
                  -> '2004-04-31'

     *Note*:

     You cannot use format `"%X%V"' to convert a year-week string to a
     date because the combination of a year and week does not uniquely
     identify a year and month if the week crosses a month boundary. To
     convert a year-week to a date, then you should also specify the
     weekday:

          mysql> SELECT STR_TO_DATE('200442 Monday', '%X%V %W');
                  -> '2004-10-18'

   *  `SUBDATE(DATE,INTERVAL EXPR UNIT)', `SUBDATE(EXPR,DAYS)'

     When invoked with the `INTERVAL' form of the second argument,
     `SUBDATE()' is a synonym for `DATE_SUB()'. For information on the
     `INTERVAL' UNIT argument, see the discussion for `DATE_ADD()'.

          mysql> SELECT DATE_SUB('2008-01-02', INTERVAL 31 DAY);
                  -> '2007-12-02'
          mysql> SELECT SUBDATE('2008-01-02', INTERVAL 31 DAY);
                  -> '2007-12-02'

     The second form allows the use of an integer value for DAYS. In
     such cases, it is interpreted as the number of days to be
     subtracted from the date or datetime expression EXPR.

          mysql> SELECT SUBDATE('2008-01-02 12:00:00', 31);
                  -> '2007-12-02 12:00:00'

   *  `SUBTIME(EXPR1,EXPR2)'

     `SUBTIME()' returns EXPR1 - EXPR2 expressed as a value in the same
     format as EXPR1.  EXPR1 is a time or datetime expression, and
     EXPR2 is a time expression.

          mysql> SELECT SUBTIME('2007-12-31 23:59:59.999999','1 1:1:1.000002');
                  -> '2007-12-30 22:58:58.999997'
          mysql> SELECT SUBTIME('01:00:00.999999', '02:00:00.999998');
                  -> '-00:59:59.999999'

   *  `SYSDATE()'

     Returns the current date and time as a value in `'YYYY-MM-DD
     HH:MM:SS'' or `YYYYMMDDHHMMSS.uuuuuu' format, depending on whether
     the function is used in a string or numeric context.

     `SYSDATE()' returns the time at which it executes. This differs
     from the behavior for `NOW()', which returns a constant time that
     indicates the time at which the statement began to execute.
     (Within a stored routine or trigger, `NOW()' returns the time at
     which the routine or triggering statement began to execute.)

          mysql> SELECT NOW(), SLEEP(2), NOW();
          +---------------------+----------+---------------------+
          | NOW()               | SLEEP(2) | NOW()               |
          +---------------------+----------+---------------------+
          | 2006-04-12 13:47:36 |        0 | 2006-04-12 13:47:36 |
          +---------------------+----------+---------------------+

          mysql> SELECT SYSDATE(), SLEEP(2), SYSDATE();
          +---------------------+----------+---------------------+
          | SYSDATE()           | SLEEP(2) | SYSDATE()           |
          +---------------------+----------+---------------------+
          | 2006-04-12 13:47:44 |        0 | 2006-04-12 13:47:46 |
          +---------------------+----------+---------------------+

     In addition, the `SET TIMESTAMP' statement affects the value
     returned by `NOW()' but not by `SYSDATE()'. This means that
     timestamp settings in the binary log have no effect on invocations
     of `SYSDATE()'.

     Because `SYSDATE()' can return different values even within the
     same statement, and is not affected by `SET TIMESTAMP', it is
     non-deterministic and therefore unsafe for replication if
     statement-based binary logging is used. If that is a problem, you
     can use row-based logging, or start the server with the
     `--sysdate-is-now' option to cause `SYSDATE()' to be an alias for
     `NOW()'. The non-deterministic nature of `SYSDATE()' also means
     that indexes cannot be used for evaluating expressions that refer
     to it.

   *  `TIME(EXPR)'

     Extracts the time part of the time or datetime expression EXPR and
     returns it as a string.

          mysql> SELECT TIME('2003-12-31 01:02:03');
                  -> '01:02:03'
          mysql> SELECT TIME('2003-12-31 01:02:03.000123');
                  -> '01:02:03.000123'

   *  `TIMEDIFF(EXPR1,EXPR2)'

     `TIMEDIFF()' returns EXPR1 - EXPR2 expressed as a time value.
     EXPR1 and EXPR2 are time or date-and-time expressions, but both
     must be of the same type.

          mysql> SELECT TIMEDIFF('2000:01:01 00:00:00',
              ->                 '2000:01:01 00:00:00.000001');
                  -> '-00:00:00.000001'
          mysql> SELECT TIMEDIFF('2008-12-31 23:59:59.000001',
              ->                 '2008-12-30 01:01:01.000002');
                  -> '46:58:57.999999'

   *  `TIMESTAMP(EXPR)', `TIMESTAMP(EXPR1,EXPR2)'

     With a single argument, this function returns the date or datetime
     expression EXPR as a datetime value. With two arguments, it adds
     the time expression EXPR2 to the date or datetime expression EXPR1
     and returns the result as a datetime value.

          mysql> SELECT TIMESTAMP('2003-12-31');
                  -> '2003-12-31 00:00:00'
          mysql> SELECT TIMESTAMP('2003-12-31 12:00:00','12:00:00');
                  -> '2004-01-01 00:00:00'

   *  `TIMESTAMPADD(UNIT,INTERVAL,DATETIME_EXPR)'

     Adds the integer expression INTERVAL to the date or datetime
     expression DATETIME_EXPR. The unit for INTERVAL is given by the
     UNIT argument, which should be one of the following values:
     `FRAC_SECOND' (microseconds), `SECOND', `MINUTE', `HOUR', `DAY',
     `WEEK', `MONTH', `QUARTER', or `YEAR'.

     Beginning with MySQL 6.0.5, it is possible to use `MICROSECOND' in
     place of `FRAC_SECOND' with this function, and `FRAC_SECOND' is
     deprecated.

     The UNIT value may be specified using one of keywords as shown, or
     with a prefix of `SQL_TSI_'. For example, `DAY' and `SQL_TSI_DAY'
     both are legal.

          mysql> SELECT TIMESTAMPADD(MINUTE,1,'2003-01-02');
                  -> '2003-01-02 00:01:00'
          mysql> SELECT TIMESTAMPADD(WEEK,1,'2003-01-02');
                  -> '2003-01-09'

   *  `TIMESTAMPDIFF(UNIT,DATETIME_EXPR1,DATETIME_EXPR2)'

     Returns `DATETIME_EXPR2 - DATETIME_EXPR1', where DATETIME_EXPR1 and
     DATETIME_EXPR2 are date or datetime expressions. One expression
     may be a date and the other a datetime; a date value is treated as
     a datetime having the time part `'00:00:00'' where necessary. The
     unit for the result (an integer) is given by the UNIT argument.
     The legal values for UNIT are the same as those listed in the
     description of the `TIMESTAMPADD()' function.

          mysql> SELECT TIMESTAMPDIFF(MONTH,'2003-02-01','2003-05-01');
                  -> 3
          mysql> SELECT TIMESTAMPDIFF(YEAR,'2002-05-01','2001-01-01');
                  -> -1
          mysql> SELECT TIMESTAMPDIFF(MINUTE,'2003-02-01','2003-05-01 12:05:55');
                  -> 128885

     *Note*:

     The order of the date or datetime arguments for this function is
     the opposite of that used with the `TIMESTAMP()' function when
     invoked with 2 arguments.

   *  `TIME_FORMAT(TIME,FORMAT)'

     This is used like the `DATE_FORMAT()' function, but the FORMAT
     string may contain format specifiers only for hours, minutes, and
     seconds. Other specifiers produce a `NULL' value or `0'.

     If the TIME value contains an hour part that is greater than `23',
     the `%H' and `%k' hour format specifiers produce a value larger
     than the usual range of `0..23'. The other hour format specifiers
     produce the hour value modulo 12.

          mysql> SELECT TIME_FORMAT('100:00:00', '%H %k %h %I %l');
                  -> '100 100 04 04 4'

   *  `TIME_TO_SEC(TIME)'

     Returns the TIME argument, converted to seconds.

          mysql> SELECT TIME_TO_SEC('22:23:00');
                  -> 80580
          mysql> SELECT TIME_TO_SEC('00:39:38');
                  -> 2378

   *  `TO_DAYS(DATE)'

     Given a date DATE, returns a day number (the number of days since
     year 0).

          mysql> SELECT TO_DAYS(950501);
                  -> 728779
          mysql> SELECT TO_DAYS('2007-10-07');
                  -> 733321

     `TO_DAYS()' is not intended for use with values that precede the
     advent of the Gregorian calendar (1582), because it does not take
     into account the days that were lost when the calendar was
     changed. For dates before 1582 (and possibly a later year in other
     locales), results from this function are not reliable. See *Note
     mysql-calendar::, for details.

     Remember that MySQL converts two-digit year values in dates to
     four-digit form using the rules in *Note date-and-time-types::.
     For example, `'2008-10-07'' and `'08-10-07'' are seen as identical
     dates:

          mysql> SELECT TO_DAYS('2008-10-07'), TO_DAYS('08-10-07');
                  -> 733687, 733687

   *  `UNIX_TIMESTAMP()', `UNIX_TIMESTAMP(DATE)'

     If called with no argument, returns a Unix timestamp (seconds
     since `'1970-01-01 00:00:00'' UTC) as an unsigned integer. If
     `UNIX_TIMESTAMP()' is called with a DATE argument, it returns the
     value of the argument as seconds since `'1970-01-01 00:00:00''
     UTC. DATE may be a *Note `DATE': datetime. string, a *Note
     `DATETIME': datetime. string, a *Note `TIMESTAMP': datetime, or a
     number in the format `YYMMDD' or `YYYYMMDD'. The server interprets
     DATE as a value in the current time zone and converts it to an
     internal value in UTC. Clients can set their time zone as
     described in *Note time-zone-support::.

          mysql> SELECT UNIX_TIMESTAMP();
                  -> 1196440210
          mysql> SELECT UNIX_TIMESTAMP('2007-11-30 10:30:19');
                  -> 1196440219

     When `UNIX_TIMESTAMP()' is used on a *Note `TIMESTAMP': datetime.
     column, the function returns the internal timestamp value
     directly, with no implicit `string-to-Unix-timestamp' conversion.
     If you pass an out-of-range date to `UNIX_TIMESTAMP()', it returns
     `0'.

     Note: If you use `UNIX_TIMESTAMP()' and `FROM_UNIXTIME()' to
     convert between *Note `TIMESTAMP': datetime. values and Unix
     timestamp values, the conversion is lossy because the mapping is
     not one-to-one in both directions. For example, due to conventions
     for local time zone changes, it is possible for two
     `UNIX_TIMESTAMP()' to map two *Note `TIMESTAMP': datetime. values
     to the same Unix timestamp value.  `FROM_UNIXTIME()' will map that
     value back to only one of the original *Note `TIMESTAMP':
     datetime. values. Here is an example, using *Note `TIMESTAMP':
     datetime. values in the `CET' time zone:

          mysql> SELECT UNIX_TIMESTAMP('2005-03-27 03:00:00');
          +---------------------------------------+
          | UNIX_TIMESTAMP('2005-03-27 03:00:00') |
          +---------------------------------------+
          |                            1111885200 |
          +---------------------------------------+
          mysql> SELECT UNIX_TIMESTAMP('2005-03-27 02:00:00');
          +---------------------------------------+
          | UNIX_TIMESTAMP('2005-03-27 02:00:00') |
          +---------------------------------------+
          |                            1111885200 |
          +---------------------------------------+
          mysql> SELECT FROM_UNIXTIME(1111885200);
          +---------------------------+
          | FROM_UNIXTIME(1111885200) |
          +---------------------------+
          | 2005-03-27 03:00:00       |
          +---------------------------+

     If you want to subtract `UNIX_TIMESTAMP()' columns, you might want
     to cast the result to signed integers. See *Note cast-functions::.

   *  `UTC_DATE', `UTC_DATE()'

     Returns the current UTC date as a value in `'YYYY-MM-DD'' or
     `YYYYMMDD' format, depending on whether the function is used in a
     string or numeric context.

          mysql> SELECT UTC_DATE(), UTC_DATE() + 0;
                  -> '2003-08-14', 20030814

   *  `UTC_TIME', `UTC_TIME()'

     Returns the current UTC time as a value in `'HH:MM:SS'' or
     `HHMMSS.uuuuuu' format, depending on whether the function is used
     in a string or numeric context.

          mysql> SELECT UTC_TIME(), UTC_TIME() + 0;
                  -> '18:07:53', 180753.000000

   *  `UTC_TIMESTAMP', `UTC_TIMESTAMP()'

     Returns the current UTC date and time as a value in `'YYYY-MM-DD
     HH:MM:SS'' or `YYYYMMDDHHMMSS.uuuuuu' format, depending on whether
     the function is used in a string or numeric context.

          mysql> SELECT UTC_TIMESTAMP(), UTC_TIMESTAMP() + 0;
                  -> '2003-08-14 18:08:04', 20030814180804.000000

   *  `WEEK(DATE[,MODE])'

     This function returns the week number for DATE. The two-argument
     form of `WEEK()' allows you to specify whether the week starts on
     Sunday or Monday and whether the return value should be in the
     range from `0' to `53' or from `1' to `53'. If the MODE argument
     is omitted, the value of the `default_week_format' system variable
     is used. See *Note server-system-variables::.

     The following table describes how the MODE argument works.

     *Mode*  *First day    *Range*       *Week 1 is the first week ...*
             of week*                    
     0       Sunday        0-53          with a Sunday in this year
     1       Monday        0-53          with more than 3 days this year
     2       Sunday        1-53          with a Sunday in this year
     3       Monday        1-53          with more than 3 days this year
     4       Sunday        0-53          with more than 3 days this year
     5       Monday        0-53          with a Monday in this year
     6       Sunday        1-53          with more than 3 days this year
     7       Monday        1-53          with a Monday in this year

          mysql> SELECT WEEK('2008-02-20');
                  -> 7
          mysql> SELECT WEEK('2008-02-20',0);
                  -> 7
          mysql> SELECT WEEK('2008-02-20',1);
                  -> 8
          mysql> SELECT WEEK('2008-12-31',1);
                  -> 53

     Note that if a date falls in the last week of the previous year,
     MySQL returns `0' if you do not use `2', `3', `6', or `7' as the
     optional MODE argument:

          mysql> SELECT YEAR('2000-01-01'), WEEK('2000-01-01',0);
                  -> 2000, 0

     One might argue that MySQL should return `52' for the `WEEK()'
     function, because the given date actually occurs in the 52nd week
     of 1999. We decided to return `0' instead because we want the
     function to return `the week number in the given year.' This makes
     use of the `WEEK()' function reliable when combined with other
     functions that extract a date part from a date.

     If you would prefer the result to be evaluated with respect to the
     year that contains the first day of the week for the given date,
     use `0', `2', `5', or `7' as the optional MODE argument.

          mysql> SELECT WEEK('2000-01-01',2);
                  -> 52

     Alternatively, use the `YEARWEEK()' function:

          mysql> SELECT YEARWEEK('2000-01-01');
                  -> 199952
          mysql> SELECT MID(YEARWEEK('2000-01-01'),5,2);
                  -> '52'

   *  `WEEKDAY(DATE)'

     Returns the weekday index for DATE (`0' = Monday, `1' = Tuesday,
     ... `6' = Sunday).

          mysql> SELECT WEEKDAY('2008-02-03 22:23:00');
                  -> 6
          mysql> SELECT WEEKDAY('2007-11-06');
                  -> 1

   *  `WEEKOFYEAR(DATE)'

     Returns the calendar week of the date as a number in the range
     from `1' to `53'.  `WEEKOFYEAR()' is a compatibility function that
     is equivalent to `WEEK(DATE,3)'.

          mysql> SELECT WEEKOFYEAR('2008-02-20');
                  -> 8

   *  `YEAR(DATE)'

     Returns the year for DATE, in the range `1000' to `9999', or `0'
     for the `zero' date.

          mysql> SELECT YEAR('1987-01-01');
                  -> 1987

   *  `YEARWEEK(DATE)', `YEARWEEK(DATE,MODE)'

     Returns year and week for a date. The MODE argument works exactly
     like the MODE argument to `WEEK()'. The year in the result may be
     different from the year in the date argument for the first and the
     last week of the year.

          mysql> SELECT YEARWEEK('1987-01-01');
                  -> 198653

     Note that the week number is different from what the `WEEK()'
     function would return (`0') for optional arguments `0' or `1', as
     `WEEK()' then returns the week in the context of the given year.


File: manual.info,  Node: mysql-calendar,  Next: fulltext-search,  Prev: date-and-time-functions,  Up: functions

11.7 What Calendar Is Used By MySQL?
====================================

MySQL uses what is known as a _proleptic Gregorian calendar_.

Every country that has switched from the Julian to the Gregorian
calendar has had to discard at least ten days during the switch.  To
see how this works, consider the month of October 1582, when the first
Julian-to-Gregorian switch occurred.

Monday     Tuesday    Wednesday  Thursday   Friday     Saturday   Sunday
1          2          3          4          15         16         17
18         19         20         21         22         23         24
25         26         27         28         29         30         31

There are no dates between October 4 and October 15. This discontinuity
is called the _cutover_. Any dates before the cutover are Julian, and
any dates following the cutover are Gregorian. Dates during a cutover
are non-existent.

A calendar applied to dates when it wasn't actually in use is called
_proleptic_. Thus, if we assume there was never a cutover and Gregorian
rules always rule, we have a proleptic Gregorian calendar. This is what
is used by MySQL, as is required by standard SQL. For this reason,
dates prior to the cutover stored as MySQL *Note `DATE': datetime. or
*Note `DATETIME': datetime. values must be adjusted to compensate for
the difference. It is important to realize that the cutover did not
occur at the same time in all countries, and that the later it
happened, the more days were lost. For example, in Great Britain, it
took place in 1752, when Wednesday September 2 was followed by Thursday
September 14. Russia remained on the Julian calendar until 1918, losing
13 days in the process, and what is popularly referred to as its
`October Revolution' occurred in November according to the Gregorian
calendar.


File: manual.info,  Node: fulltext-search,  Next: cast-functions,  Prev: mysql-calendar,  Up: functions

11.8 Full-Text Search Functions
===============================

* Menu:

* fulltext-natural-language::    Natural Language Full-Text Searches
* fulltext-boolean::             Boolean Full-Text Searches
* fulltext-query-expansion::     Full-Text Searches with Query Expansion
* fulltext-stopwords::           Full-Text Stopwords
* fulltext-restrictions::        Full-Text Restrictions
* fulltext-fine-tuning::         Fine-Tuning MySQL Full-Text Search

`MATCH (COL1,COL2,...)  AGAINST (EXPR [SEARCH_MODIFIER])'

     SEARCH_MODIFIER:
       {
            IN BOOLEAN MODE
          | IN NATURAL LANGUAGE MODE
          | IN NATURAL LANGUAGE MODE WITH QUERY EXPANSION
          | WITH QUERY EXPANSION
       }

MySQL has support for full-text indexing and searching:

   * A full-text index in MySQL is an index of type `FULLTEXT'.

   * Full-text indexes can be used only with `MyISAM' tables, and can
     be created only for *Note `CHAR': char, *Note `VARCHAR': char, or
     *Note `TEXT': blob. columns.

   * A `FULLTEXT' index definition can be given in the *Note `CREATE
     TABLE': create-table. statement when a table is created, or added
     later using *Note `ALTER TABLE': alter-table. or *Note `CREATE
     INDEX': create-index.

   * For large data sets, it is much faster to load your data into a
     table that has no `FULLTEXT' index and then create the index after
     that, than to load data into a table that has an existing
     `FULLTEXT' index.

Full-text searching is performed using `MATCH() ... AGAINST' syntax.
`MATCH()' takes a comma-separated list that names the columns to be
searched.  `AGAINST' takes a string to search for, and an optional
modifier that indicates what type of search to perform.  The search
string must be a literal string, not a variable or a column name. There
are three types of full-text searches:

   * A boolean search interprets the search string using the rules of a
     special query language. The string contains the words to search
     for. It can also contain operators that specify requirements such
     that a word must be present or absent in matching rows, or that it
     should be weighted higher or lower than usual. Common words such
     as `some' or `then' are stopwords and do not match if present in
     the search string. The `IN BOOLEAN MODE' modifier specifies a
     boolean search. For more information, see *Note fulltext-boolean::.

   * A natural language search interprets the search string as a phrase
     in natural human language (a phrase in free text).  There are no
     special operators. The stopword list applies. In addition, words
     that are present in 50% or more of the rows are considered common
     and do not match. Full-text searches are natural language searches
     if the `IN NATURAL LANGUAGE MODE' modifier is given or if no
     modifier is given.

   * A query expansion search is a modification of a natural language
     search. The search string is used to perform a natural language
     search. Then words from the most relevant rows returned by the
     search are added to the search string and the search is done
     again. The query returns the rows from the second search. The `IN
     NATURAL LANGUAGE MODE WITH QUERY EXPANSION' or `WITH QUERY
     EXPANSION' modifier specifies a query expansion search. For more
     information, see *Note fulltext-query-expansion::.

Constraints on full-text searching are listed in *Note
fulltext-restrictions::.


File: manual.info,  Node: fulltext-natural-language,  Next: fulltext-boolean,  Prev: fulltext-search,  Up: fulltext-search

11.8.1 Natural Language Full-Text Searches
------------------------------------------

By default or with the `IN NATURAL LANGUAGE MODE' modifier, the
`MATCH()' function performs a natural language search for a string
against a _text collection_. A collection is a set of one or more
columns included in a `FULLTEXT' index. The search string is given as
the argument to `AGAINST()'. For each row in the table, `MATCH()'
returns a relevance value; that is, a similarity measure between the
search string and the text in that row in the columns named in the
`MATCH()' list.

     mysql> CREATE TABLE articles (
         ->   id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
         ->   title VARCHAR(200),
         ->   body TEXT,
         ->   FULLTEXT (title,body)
         -> );
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO articles (title,body) VALUES
         -> ('MySQL Tutorial','DBMS stands for DataBase ...'),
         -> ('How To Use MySQL Well','After you went through a ...'),
         -> ('Optimizing MySQL','In this tutorial we will show ...'),
         -> ('1001 MySQL Tricks','1. Never run mysqld as root. 2. ...'),
         -> ('MySQL vs. YourSQL','In the following database comparison ...'),
         -> ('MySQL Security','When configured properly, MySQL ...');
     Query OK, 6 rows affected (0.00 sec)
     Records: 6  Duplicates: 0  Warnings: 0

     mysql> SELECT * FROM articles
         -> WHERE MATCH (title,body)
         -> AGAINST ('database' IN NATURAL LANGUAGE MODE);
     +----+-------------------+------------------------------------------+
     | id | title             | body                                     |
     +----+-------------------+------------------------------------------+
     |  5 | MySQL vs. YourSQL | In the following database comparison ... |
     |  1 | MySQL Tutorial    | DBMS stands for DataBase ...             |
     +----+-------------------+------------------------------------------+
     2 rows in set (0.00 sec)

By default, the search is performed in case-insensitive fashion.
However, you can perform a case-sensitive full-text search by using a
binary collation for the indexed columns. For example, a column that
uses the `latin1' character set of can be assigned a collation of
`latin1_bin' to make it case sensitive for full-text searches.

When `MATCH()' is used in a `WHERE' clause, as in the example shown
earlier, the rows returned are automatically sorted with the highest
relevance first. Relevance values are non-negative floating-point
numbers. Zero relevance means no similarity.  Relevance is computed
based on the number of words in the row, the number of unique words in
that row, the total number of words in the collection, and the number
of documents (rows) that contain a particular word.

To simply count matches, you could use a query like this:

     mysql> SELECT COUNT(*) FROM articles
         -> WHERE MATCH (title,body)
         -> AGAINST ('database' IN NATURAL LANGUAGE MODE);
     +----------+
     | COUNT(*) |
     +----------+
     |        2 |
     +----------+
     1 row in set (0.00 sec)

However, you might find it quicker to rewrite the query as follows:

     mysql> SELECT
         -> COUNT(IF(MATCH (title,body) AGAINST ('database' IN NATURAL LANGUAGE MODE), 1, NULL))
         -> AS count
         -> FROM articles;
     +-------+
     | count |
     +-------+
     |     2 |
     +-------+
     1 row in set (0.03 sec)

The first query sorts the results by relevance whereas the second does
not. However, the second query performs a full table scan and the first
does not. The first may be faster if the search matches few rows;
otherwise, the second may be faster because it would read many rows
anyway.

For natural-language full-text searches, it is a requirement that the
columns named in the `MATCH()' function be the same columns included in
some `FULLTEXT' index in your table. For the preceding query, note that
the columns named in the `MATCH()' function (`title' and `body') are the
same as those named in the definition of the `article' table's
`FULLTEXT' index. If you wanted to search the `title' or `body'
separately, you would need to create separate `FULLTEXT' indexes for
each column.

It is also possible to perform a boolean search or a search with query
expansion. These search types are described in *Note
fulltext-boolean::, and *Note fulltext-query-expansion::.

A full-text search that uses an index can name columns only from a
single table in the `MATCH()' clause because an index cannot span
multiple tables. A boolean search can be done in the absence of an
index (albeit more slowly), in which case it is possible to name
columns from multiple tables.

The preceding example is a basic illustration that shows how to use the
`MATCH()' function where rows are returned in order of decreasing
relevance. The next example shows how to retrieve the relevance values
explicitly.  Returned rows are not ordered because the *Note `SELECT':
select. statement includes neither `WHERE' nor `ORDER BY' clauses:

     mysql> SELECT id, MATCH (title,body)
         -> AGAINST ('Tutorial' IN NATURAL LANGUAGE MODE) AS score
         -> FROM articles;
     +----+------------------+
     | id | score            |
     +----+------------------+
     |  1 | 0.65545833110809 |
     |  2 |                0 |
     |  3 | 0.66266459226608 |
     |  4 |                0 |
     |  5 |                0 |
     |  6 |                0 |
     +----+------------------+
     6 rows in set (0.00 sec)

The following example is more complex. The query returns the relevance
values and it also sorts the rows in order of decreasing relevance. To
achieve this result, you should specify `MATCH()' twice: once in the
*Note `SELECT': select. list and once in the `WHERE' clause. This
causes no additional overhead, because the MySQL optimizer notices that
the two `MATCH()' calls are identical and invokes the full-text search
code only once.

     mysql> SELECT id, body, MATCH (title,body) AGAINST
         -> ('Security implications of running MySQL as root'
         -> IN NATURAL LANGUAGE MODE) AS score
         -> FROM articles WHERE MATCH (title,body) AGAINST
         -> ('Security implications of running MySQL as root'
         -> IN NATURAL LANGUAGE MODE);
     +----+-------------------------------------+-----------------+
     | id | body                                | score           |
     +----+-------------------------------------+-----------------+
     |  4 | 1. Never run mysqld as root. 2. ... | 1.5219271183014 |
     |  6 | When configured properly, MySQL ... | 1.3114095926285 |
     +----+-------------------------------------+-----------------+
     2 rows in set (0.00 sec)

The MySQL `FULLTEXT' implementation regards any sequence of true word
characters (letters, digits, and underscores) as a word. That sequence
may also contain apostrophes (``'''), but not more than one in a row.
This means that `aaa'bbb' is regarded as one word, but `aaa''bbb' is
regarded as two words. Apostrophes at the beginning or the end of a
word are stripped by the `FULLTEXT' parser; `'aaa'bbb'' would be parsed
as `aaa'bbb'.

The `FULLTEXT' parser determines where words start and end by looking
for certain delimiter characters; for example, `` '' (space), ``,''
(comma), and ``.'' (period). If words are not separated by delimiters
(as in, for example, Chinese), the `FULLTEXT' parser cannot determine
where a word begins or ends. To be able to add words or other indexed
terms in such languages to a `FULLTEXT' index, you must preprocess them
so that they are separated by some arbitrary delimiter such as ``"''.

In MySQL 6.0, it is possible to write a plugin that replaces the
built-in full-text parser. For details, see *Note plugin-api::. For
example parser plugin source code, see the `plugin/fulltext' directory
of a MySQL source distribution.

Some words are ignored in full-text searches:

   * Any word that is too short is ignored. The default minimum length
     of words that are found by full-text searches is four characters.

   * Words in the stopword list are ignored. A stopword is a word such
     as `the' or `some' that is so common that it is considered to have
     zero semantic value.  There is a built-in stopword list, but it
     can be overwritten by a user-defined list.

The default stopword list is given in *Note fulltext-stopwords::. The
default minimum word length and stopword list can be changed as
described in *Note fulltext-fine-tuning::.

Every correct word in the collection and in the query is weighted
according to its significance in the collection or query. Consequently,
a word that is present in many documents has a lower weight (and may
even have a zero weight), because it has lower semantic value in this
particular collection.  Conversely, if the word is rare, it receives a
higher weight.  The weights of the words are combined to compute the
relevance of the row.

Such a technique works best with large collections (in fact, it was
carefully tuned this way). For very small tables, word distribution
does not adequately reflect their semantic value, and this model may
sometimes produce bizarre results. For example, although the word
`MySQL' is present in every row of the `articles' table shown earlier,
a search for the word produces no results:

     mysql> SELECT * FROM articles
         -> WHERE MATCH (title,body)
         -> AGAINST ('MySQL' IN NATURAL LANGUAGE MODE);
     Empty set (0.00 sec)

The search result is empty because the word `MySQL' is present in at
least 50% of the rows. As such, it is effectively treated as a
stopword. For large data sets, this is the most desirable behavior: A
natural language query should not return every second row from a 1GB
table. For small data sets, it may be less desirable.

A word that matches half of the rows in a table is less likely to
locate relevant documents. In fact, it most likely finds plenty of
irrelevant documents. We all know this happens far too often when we
are trying to find something on the Internet with a search engine. It
is with this reasoning that rows containing the word are assigned a low
semantic value for _the particular data set in which they occur_. A
given word may reach the 50% threshold in one data set but not another.

The 50% threshold has a significant implication when you first try
full-text searching to see how it works: If you create a table and
insert only one or two rows of text into it, every word in the text
occurs in at least 50% of the rows. As a result, no search returns any
results. Be sure to insert at least three rows, and preferably many
more. Users who need to bypass the 50% limitation can use the boolean
search mode; see *Note fulltext-boolean::.


File: manual.info,  Node: fulltext-boolean,  Next: fulltext-query-expansion,  Prev: fulltext-natural-language,  Up: fulltext-search

11.8.2 Boolean Full-Text Searches
---------------------------------

MySQL can perform boolean full-text searches using the `IN BOOLEAN
MODE' modifier:

     mysql> SELECT * FROM articles WHERE MATCH (title,body)
         -> AGAINST ('+MySQL -YourSQL' IN BOOLEAN MODE);
     +----+-----------------------+-------------------------------------+
     | id | title                 | body                                |
     +----+-----------------------+-------------------------------------+
     |  1 | MySQL Tutorial        | DBMS stands for DataBase ...        |
     |  2 | How To Use MySQL Well | After you went through a ...        |
     |  3 | Optimizing MySQL      | In this tutorial we will show ...   |
     |  4 | 1001 MySQL Tricks     | 1. Never run mysqld as root. 2. ... |
     |  6 | MySQL Security        | When configured properly, MySQL ... |
     +----+-----------------------+-------------------------------------+

The `+' and `-' operators indicate that a word is required to be
present or absent, respectively, for a match to occur. Thus, this query
retrieves all the rows that contain the word `MySQL' but that do _not_
contain the word `YourSQL'.

*Note*:

In implementing this feature, MySQL uses what is sometimes referred to
as _implied Boolean logic_, in which

   * `+' stands for `AND'

   * `-' stands for `NOT'

   * [_no operator_] implies `OR'

Boolean full-text searches have these characteristics:

   * They do not use the 50% threshold.

   * They do not automatically sort rows in order of decreasing
     relevance. You can see this from the preceding query result: The
     row with the highest relevance is the one that contains `MySQL'
     twice, but it is listed last, not first.

   * They can work even without a `FULLTEXT' index, although a search
     executed in this fashion would be quite slow.

   * The minimum and maximum word length full-text parameters apply.

   * The stopword list applies.

The boolean full-text search capability supports the following
operators:

   * `+'

     A leading plus sign indicates that this word _must_ be present in
     each row that is returned.

   * `-'

     A leading minus sign indicates that this word must _not_ be
     present in any of the rows that are returned.

     Note: The `-' operator acts only to exclude rows that are
     otherwise matched by other search terms. Thus, a boolean-mode
     search that contains only terms preceded by `-' returns an empty
     result. It does not return `all rows except those containing any
     of the excluded terms.'

   * (no operator)

     By default (when neither `+' nor `-' is specified) the word is
     optional, but the rows that contain it are rated higher. This
     mimics the behavior of `MATCH() ...  AGAINST()' without the `IN
     BOOLEAN MODE' modifier.

   * `> <'

     These two operators are used to change a word's contribution to
     the relevance value that is assigned to a row. The `>' operator
     increases the contribution and the `<' operator decreases it. See
     the example following this list.

   * `( )'

     Parentheses group words into subexpressions. Parenthesized groups
     can be nested.

   * `~'

     A leading tilde acts as a negation operator, causing the word's
     contribution to the row's relevance to be negative.  This is
     useful for marking `noise' words. A row containing such a word is
     rated lower than others, but is not excluded altogether, as it
     would be with the `-' operator.

   * `*'

     The asterisk serves as the truncation (or wildcard) operator.
     Unlike the other operators, it should be _appended_ to the word to
     be affected.  Words match if they begin with the word preceding the
     `*' operator.

     If a stopword or too-short word is specified with the truncation
     operator, it will not be stripped from a boolean query. For
     example, a search for `'+word +stopword*'' will likely return
     fewer rows than a search for `'+word +stopword'' because the
     former query remains as is and requires `stopword*' to be present
     in a document.  The latter query is transformed to `+word'.

   * `"'

     A phrase that is enclosed within double quote (``"'') characters
     matches only rows that contain the phrase _literally, as it was
     typed_. The full-text engine splits the phrase into words,
     performs a search in the `FULLTEXT' index for the words. Non-word
     characters need not be matched exactly: Phrase searching requires
     only that matches contain exactly the same words as the phrase and
     in the same order. For example, `"test phrase"' matches `"test,
     phrase"'.

     If the phrase contains no words that are in the index, the result
     is empty. For example, if all words are either stopwords or
     shorter than the minimum length of indexed words, the result is
     empty.

The following examples demonstrate some search strings that use boolean
full-text operators:

   * `'apple banana''

     Find rows that contain at least one of the two words.

   * `'+apple +juice''

     Find rows that contain both words.

   * `'+apple macintosh''

     Find rows that contain the word `apple', but rank rows higher if
     they also contain `macintosh'.

   * `'+apple -macintosh''

     Find rows that contain the word `apple' but not `macintosh'.

   * `'+apple ~macintosh''

     Find rows that contain the word `apple', but if the row also
     contains the word `macintosh', rate it lower than if row does not.
     This is `softer' than a search for `'+apple -macintosh'', for
     which the presence of `macintosh' causes the row not to be returned
     at all.

   * `'+apple +(>turnover <strudel)''

     Find rows that contain the words `apple' and `turnover', or
     `apple' and `strudel' (in any order), but rank `apple turnover'
     higher than `apple strudel'.

   * `'apple*''

     Find rows that contain words such as `apple', `apples',
     `applesauce', or `applet'.

   * `'"some words"''

     Find rows that contain the exact phrase `some words' (for example,
     rows that contain `some words of wisdom' but not `some noise
     words'). Note that the ``"'' characters that enclose the phrase
     are operator characters that delimit the phrase.  They are not the
     quotes that enclose the search string itself.


File: manual.info,  Node: fulltext-query-expansion,  Next: fulltext-stopwords,  Prev: fulltext-boolean,  Up: fulltext-search

11.8.3 Full-Text Searches with Query Expansion
----------------------------------------------

Full-text search supports query expansion (and in particular, its
variant `blind query expansion'). This is generally useful when a
search phrase is too short, which often means that the user is relying
on implied knowledge that the full-text search engine lacks. For
example, a user searching for `database' may really mean that `MySQL',
`Oracle', `DB2', and `RDBMS' all are phrases that should match
`databases' and should be returned, too. This is implied knowledge.

Blind query expansion (also known as automatic relevance feedback) is
enabled by adding `WITH QUERY EXPANSION' or `IN NATURAL LANGUAGE MODE
WITH QUERY EXPANSION' following the search phrase. It works by
performing the search twice, where the search phrase for the second
search is the original search phrase concatenated with the few most
highly relevant documents from the first search.  Thus, if one of these
documents contains the word `databases' and the word `MySQL', the
second search finds the documents that contain the word `MySQL' even if
they do not contain the word `database'. The following example shows
this difference:

     mysql> SELECT * FROM articles
         -> WHERE MATCH (title,body)
         -> AGAINST ('database' IN NATURAL LANGUAGE MODE);
     +----+-------------------+------------------------------------------+
     | id | title             | body                                     |
     +----+-------------------+------------------------------------------+
     |  5 | MySQL vs. YourSQL | In the following database comparison ... |
     |  1 | MySQL Tutorial    | DBMS stands for DataBase ...             |
     +----+-------------------+------------------------------------------+
     2 rows in set (0.00 sec)

     mysql> SELECT * FROM articles
         -> WHERE MATCH (title,body)
         -> AGAINST ('database' WITH QUERY EXPANSION);
     +----+-------------------+------------------------------------------+
     | id | title             | body                                     |
     +----+-------------------+------------------------------------------+
     |  1 | MySQL Tutorial    | DBMS stands for DataBase ...             |
     |  5 | MySQL vs. YourSQL | In the following database comparison ... |
     |  3 | Optimizing MySQL  | In this tutorial we will show ...        |
     +----+-------------------+------------------------------------------+
     3 rows in set (0.00 sec)

Another example could be searching for books by Georges Simenon about
Maigret, when a user is not sure how to spell `Maigret'. A search for
`Megre and the reluctant witnesses' finds only `Maigret and the
Reluctant Witnesses' without query expansion. A search with query
expansion finds all books with the word `Maigret' on the second pass.

*Note*:

Because blind query expansion tends to increase noise significantly by
returning non-relevant documents, it is meaningful to use only when a
search phrase is rather short.


File: manual.info,  Node: fulltext-stopwords,  Next: fulltext-restrictions,  Prev: fulltext-query-expansion,  Up: fulltext-search

11.8.4 Full-Text Stopwords
--------------------------

The following table shows the default list of full-text stopwords.

a's            able           about          above          according
accordingly    across         actually       after          afterwards
again          against        ain't          all            allow
allows         almost         alone          along          already
also           although       always         am             among
amongst        an             and            another        any
anybody        anyhow         anyone         anything       anyway
anyways        anywhere       apart          appear         appreciate
appropriate    are            aren't         around         as
aside          ask            asking         associated     at
available      away           awfully        be             became
because        become         becomes        becoming       been
before         beforehand     behind         being          believe
below          beside         besides        best           better
between        beyond         both           brief          but
by             c'mon          c's            came           can
can't          cannot         cant           cause          causes
certain        certainly      changes        clearly        co
com            come           comes          concerning     consequently
consider       considering    contain        containing     contains
corresponding  could          couldn't       course         currently
definitely     described      despite        did            didn't
different      do             does           doesn't        doing
don't          done           down           downwards      during
each           edu            eg             eight          either
else           elsewhere      enough         entirely       especially
et             etc            even           ever           every
everybody      everyone       everything     everywhere     ex
exactly        example        except         far            few
fifth          first          five           followed       following
follows        for            former         formerly       forth
four           from           further        furthermore    get
gets           getting        given          gives          go
goes           going          gone           got            gotten
greetings      had            hadn't         happens        hardly
has            hasn't         have           haven't        having
he             he's           hello          help           hence
her            here           here's         hereafter      hereby
herein         hereupon       hers           herself        hi
him            himself        his            hither         hopefully
how            howbeit        however        i'd            i'll
i'm            i've           ie             if             ignored
immediate      in             inasmuch       inc            indeed
indicate       indicated      indicates      inner          insofar
instead        into           inward         is             isn't
it             it'd           it'll          it's           its
itself         just           keep           keeps          kept
know           knows          known          last           lately
later          latter         latterly       least          less
lest           let            let's          like           liked
likely         little         look           looking        looks
ltd            mainly         many           may            maybe
me             mean           meanwhile      merely         might
more           moreover       most           mostly         much
must           my             myself         name           namely
nd             near           nearly         necessary      need
needs          neither        never          nevertheless   new
next           nine           no             nobody         non
none           noone          nor            normally       not
nothing        novel          now            nowhere        obviously
of             off            often          oh             ok
okay           old            on             once           one
ones           only           onto           or             other
others         otherwise      ought          our            ours
ourselves      out            outside        over           overall
own            particular     particularly   per            perhaps
placed         please         plus           possible       presumably
probably       provides       que            quite          qv
rather         rd             re             really         reasonably
regarding      regardless     regards        relatively     respectively
right          said           same           saw            say
saying         says           second         secondly       see
seeing         seem           seemed         seeming        seems
seen           self           selves         sensible       sent
serious        seriously      seven          several        shall
she            should         shouldn't      since          six
so             some           somebody       somehow        someone
something      sometime       sometimes      somewhat       somewhere
soon           sorry          specified      specify        specifying
still          sub            such           sup            sure
t's            take           taken          tell           tends
th             than           thank          thanks         thanx
that           that's         thats          the            their
theirs         them           themselves     then           thence
there          there's        thereafter     thereby        therefore
therein        theres         thereupon      these          they
they'd         they'll        they're        they've        think
third          this           thorough       thoroughly     those
though         three          through        throughout     thru
thus           to             together       too            took
toward         towards        tried          tries          truly
try            trying         twice          two            un
under          unfortunately  unless         unlikely       until
unto           up             upon           us             use
used           useful         uses           using          usually
value          various        very           via            viz
vs             want           wants          was            wasn't
way            we             we'd           we'll          we're
we've          welcome        well           went           were
weren't        what           what's         whatever       when
whence         whenever       where          where's        whereafter
whereas        whereby        wherein        whereupon      wherever
whether        which          while          whither        who
who's          whoever        whole          whom           whose
why            will           willing        wish           with
within         without        won't          wonder         would
would          wouldn't       yes            yet            you
you'd          you'll         you're         you've         your
yours          yourself       yourselves     zero           


File: manual.info,  Node: fulltext-restrictions,  Next: fulltext-fine-tuning,  Prev: fulltext-stopwords,  Up: fulltext-search

11.8.5 Full-Text Restrictions
-----------------------------

   * Full-text searches are supported for `MyISAM' tables only.

   * Full-text searches can be used with most multi-byte character
     sets. The exception is that for Unicode, the `utf8' character set
     can be used, but not the `ucs2' character set. However, although
     `FULLTEXT' indexes on `ucs2' columns cannot be used, you can
     perform `IN BOOLEAN MODE' searches on a `ucs2' column that has no
     such index.

     The remarks for `utf8' also apply to `utf8mb3', and the remarks for
     `ucs2' also apply to `utf16' and `utf32'.

   * Ideographic languages such as Chinese and Japanese do not have
     word delimiters. Therefore, the `FULLTEXT' parser _cannot
     determine where words begin and end in these and other such
     languages_. The implications of this and some workarounds for the
     problem are described in *Note fulltext-search::.

   * Although the use of multiple character sets within a single table
     is supported, all columns in a `FULLTEXT' index must use the same
     character set and collation.

   * The `MATCH()' column list must match exactly the column list in
     some `FULLTEXT' index definition for the table, unless this
     `MATCH()' is `IN BOOLEAN MODE'. Boolean-mode searches can be done
     on non-indexed columns, although they are likely to be slow.

   * The argument to `AGAINST()' must be a constant string.

   * Index hints are more limited for `FULLTEXT' searches than for
     non-`FULLTEXT' searches.  See *Note index-hints::.


File: manual.info,  Node: fulltext-fine-tuning,  Prev: fulltext-restrictions,  Up: fulltext-search

11.8.6 Fine-Tuning MySQL Full-Text Search
-----------------------------------------

MySQL's full-text search capability has few user-tunable parameters.
You can exert more control over full-text searching behavior if you
have a MySQL source distribution because some changes require source
code modifications. See *Note installing-source::.

Note that full-text search is carefully tuned for the most
effectiveness. Modifying the default behavior in most cases can
actually decrease effectiveness. _Do not alter the MySQL sources unless
you know what you are doing_.

Most full-text variables described in this section must be set at
server startup time. A server restart is required to change them; they
cannot be modified while the server is running.

Some variable changes require that you rebuild the `FULLTEXT' indexes
in your tables. Instructions for doing this are given at the end of
this section.

   * The minimum and maximum lengths of words to be indexed are defined
     by the `ft_min_word_len' and `ft_max_word_len' system variables.
     (See *Note server-system-variables::.)  The default minimum value
     is four characters; the default maximum is version dependent. If
     you change either value, you must rebuild your `FULLTEXT' indexes.
     For example, if you want three-character words to be searchable,
     you can set the `ft_min_word_len' variable by putting the
     following lines in an option file:

          [mysqld]
          ft_min_word_len=3

     Then you must restart the server and rebuild your `FULLTEXT'
     indexes. Note particularly the remarks regarding *Note
     `myisamchk': myisamchk. in the instructions following this list.

   * To override the default stopword list, set the `ft_stopword_file'
     system variable. (See *Note server-system-variables::.)  The
     variable value should be the path name of the file containing the
     stopword list, or the empty string to disable stopword filtering.
     After changing the value of this variable or the contents of the
     stopword file, restart the server and rebuild your `FULLTEXT'
     indexes.

     The stopword list is free-form. That is, you may use any
     non-alphanumeric character such as newline, space, or comma to
     separate stopwords. Exceptions are the underscore character
     (``_'') and a single apostrophe (``''') which are treated as part
     of a word. The character set of the stopword list is the server's
     default character set; see *Note charset-server::.

   * The 50% threshold for natural language searches is determined by
     the particular weighting scheme chosen. To disable it, look for
     the following line in `storage/myisam/ftdefs.h':

          #define GWS_IN_USE GWS_PROB

     Change that line to this:

          #define GWS_IN_USE GWS_FREQ

     Then recompile MySQL. There is no need to rebuild the indexes in
     this case.

     *Note*:

     By making this change, you _severely_ decrease MySQL's ability to
     provide adequate relevance values for the `MATCH()' function. If
     you really need to search for such common words, it would be
     better to search using `IN BOOLEAN MODE' instead, which does not
     observe the 50% threshold.

   * To change the operators used for boolean full-text searches, set
     the `ft_boolean_syntax' system variable. This variable can be
     changed while the server is running, but you must have the `SUPER'
     privilege to do so. No rebuilding of indexes is necessary in this
     case. See *Note server-system-variables::, which describes the
     rules governing how to set this variable.

   * If you want to change the set of characters that are considered
     word characters, you can do so in two ways.  Suppose that you want
     to treat the hyphen character ('-') as a word character. Use
     either of these methods:

        * Modify the MySQL source: In `storage/myisam/ftdefs.h', see the
          `true_word_char()' and `misc_word_char()' macros. Add `'-''
          to one of those macros and recompile MySQL.

        * Modify a character set file: This requires no recompilation.
          The `true_word_char()' macro uses a `character type' table to
          distinguish letters and numbers from other characters. .  You
          can edit the `<ctype><map>' contents in one of the character
          set XML files to specify that `'-'' is a `letter.' Then use
          the given character set for your `FULLTEXT' indexes.

     After making the modification, you must rebuild the indexes for
     each table that contains any `FULLTEXT' indexes.

If you modify full-text variables that affect indexing
(`ft_min_word_len', `ft_max_word_len', or `ft_stopword_file'), or if you
change the stopword file itself, you must rebuild your `FULLTEXT'
indexes after making the changes and restarting the server. To rebuild
the indexes in this case, it is sufficient to do a `QUICK' repair
operation:

     mysql> REPAIR TABLE TBL_NAME QUICK;

Each table that contains any `FULLTEXT' index must be repaired as just
shown. Otherwise, queries for the table may yield incorrect results,
and modifications to the table will cause the server to see the table
as corrupt and in need of repair.

Note that if you use *Note `myisamchk': myisamchk. to perform an
operation that modifies table indexes (such as repair or analyze), the
`FULLTEXT' indexes are rebuilt using the _default_ full-text parameter
values for minimum word length, maximum word length, and stopword file
unless you specify otherwise. This can result in queries failing.

The problem occurs because these parameters are known only by the
server. They are not stored in `MyISAM' index files. To avoid the
problem if you have modified the minimum or maximum word length or
stopword file values used by the server, specify the same
`ft_min_word_len', `ft_max_word_len', and `ft_stopword_file' values to
*Note `myisamchk': myisamchk. that you use for *Note `mysqld': mysqld.
For example, if you have set the minimum word length to 3, you can
repair a table with *Note `myisamchk': myisamchk. like this:

     shell> myisamchk --recover --ft_min_word_len=3 TBL_NAME.MYI

To ensure that *Note `myisamchk': myisamchk. and the server use the
same values for full-text parameters, place each one in both the
`[mysqld]' and `[myisamchk]' sections of an option file:

     [mysqld]
     ft_min_word_len=3

     [myisamchk]
     ft_min_word_len=3

An alternative to using *Note `myisamchk': myisamchk. is to use the
*Note `REPAIR TABLE': repair-table, *Note `ANALYZE TABLE':
analyze-table, *Note `OPTIMIZE TABLE': optimize-table, or *Note `ALTER
TABLE': alter-table. statements. These statements are performed by the
server, which knows the proper full-text parameter values to use.


File: manual.info,  Node: cast-functions,  Next: xml-functions,  Prev: fulltext-search,  Up: functions

11.9 Cast Functions and Operators
=================================

*Name*                        *Description*
`BINARY'                      Cast a string to a binary string
`CAST()'                      Cast a value as a certain type
`Convert()'                   Cast a value as a certain type

   *  `BINARY'

     The `BINARY' operator casts the string following it to a binary
     string. This is an easy way to force a column comparison to be
     done byte by byte rather than character by character. This causes
     the comparison to be case sensitive even if the column isn't
     defined as *Note `BINARY': binary-varbinary. or *Note `BLOB': blob.
     `BINARY' also causes trailing spaces to be significant.

          mysql> SELECT 'a' = 'A';
                  -> 1
          mysql> SELECT BINARY 'a' = 'A';
                  -> 0
          mysql> SELECT 'a' = 'a ';
                  -> 1
          mysql> SELECT BINARY 'a' = 'a ';
                  -> 0

     In a comparison, `BINARY' affects the entire operation; it can be
     given before either operand with the same result.

     `BINARY STR' is shorthand for `CAST(STR AS BINARY)'.

     Note that in some contexts, if you cast an indexed column to
     `BINARY', MySQL is not able to use the index efficiently.

   *  `CAST(EXPR AS TYPE)'

     The `CAST()' function takes a value of one type and produce a
     value of another type, similar to `CONVERT()'. See the description
     of `CONVERT()' for more information.

   *  `CONVERT(EXPR,TYPE)', `CONVERT(EXPR USING TRANSCODING_NAME)'

     The `CONVERT()' and `CAST()' functions take a value of one type
     and produce a value of another type.

     The TYPE can be one of the following values:

        * `BINARY[(N)]'

        * `CHAR[(N)]'

        * *Note `DATE': datetime.

        * *Note `DATETIME': datetime.

        * `DECIMAL[(M[,D])]'

        * `SIGNED [INTEGER]'

        * *Note `TIME': time.

        * `UNSIGNED [INTEGER]'

     *Note `BINARY': binary-varbinary. produces a string with the *Note
     `BINARY': binary-varbinary. data type. See *Note
     binary-varbinary:: for a description of how this affects
     comparisons. If the optional length N is given, `BINARY(N)' causes
     the cast to use no more than N bytes of the argument. Values
     shorter than N bytes are padded with `0x00' bytes to a length of N.

     `CHAR(N)' causes the cast to use no more than N characters of the
     argument.

     `CAST()' and `CONVERT(... USING ...)' are standard SQL syntax. The
     non-`USING' form of `CONVERT()' is ODBC syntax.

     `CONVERT()' with `USING' is used to convert data between different
     character sets. In MySQL, transcoding names are the same as the
     corresponding character set names. For example, this statement
     converts the string `'abc'' in the default character set to the
     corresponding string in the `utf8' character set:

          SELECT CONVERT('abc' USING utf8);

Normally, you cannot compare a *Note `BLOB': blob.  value or other
binary string in case-insensitive fashion because binary strings have
no character set, and thus no concept of lettercase. To perform a
case-insensitive comparison, use the `CONVERT()' function to convert the
value to a non-binary string. If the character set of the result has a
case-insensitive collation, the `LIKE' operation is not case sensitive:

     SELECT 'A' LIKE CONVERT(BLOB_COL USING latin1) FROM TBL_NAME;

To use a different character set, substitute its name for `latin1' in
the preceding statement. To ensure that a case-insensitive collation is
used, specify a `COLLATE' clause following the `CONVERT()' call.

`CONVERT()' can be used more generally for comparing strings that are
represented in different character sets.

The cast functions are useful when you want to create a column with a
specific type in a `CREATE ... SELECT' statement:

     CREATE TABLE new_table SELECT CAST('2000-01-01' AS DATE);

The functions also can be useful for sorting *Note `ENUM': enum.
columns in lexical order.  Normally, sorting of *Note `ENUM': enum.
columns occurs using the internal numeric values. Casting the values to
*Note `CHAR': char. results in a lexical sort:

     SELECT ENUM_COL FROM TBL_NAME ORDER BY CAST(ENUM_COL AS CHAR);

`CAST(STR AS BINARY)' is the same thing as `BINARY STR'.  `CAST(EXPR AS
CHAR)' treats the expression as a string with the default character set.

`CAST()' also changes the result if you use it as part of a more
complex expression such as `CONCAT('Date: ',CAST(NOW() AS DATE))'.

You should not use `CAST()' to extract data in different formats but
instead use string functions like `LEFT()' or `EXTRACT()'. See *Note
date-and-time-functions::.

To cast a string to a numeric value in numeric context, you normally do
not have to do anything other than to use the string value as though it
were a number:

     mysql> SELECT 1+'1';
            -> 2

If you use a number in string context, the number automatically is
converted to a *Note `BINARY': binary-varbinary. string.

     mysql> SELECT CONCAT('hello you ',2);
             -> 'hello you 2'

MySQL supports arithmetic with both signed and unsigned 64-bit values.
If you are using numeric operators (such as `+' or `-') and one of the
operands is an unsigned integer, the result is unsigned. You can
override this by using the `SIGNED' and `UNSIGNED' cast operators to
cast the operation to a signed or unsigned 64-bit integer, respectively.

     mysql> SELECT CAST(1-2 AS UNSIGNED)
             -> 18446744073709551615
     mysql> SELECT CAST(CAST(1-2 AS UNSIGNED) AS SIGNED);
             -> -1

Note that if either operand is a floating-point value, the result is a
floating-point value and is not affected by the preceding rule. (In
this context, *Note `DECIMAL': numeric-types.  column values are
regarded as floating-point values.)

     mysql> SELECT CAST(1 AS UNSIGNED) - 2.0;
             -> -1.0

If you are using a string in an arithmetic operation, this is converted
to a floating-point number.

If you convert a `zero' date string to a date, `CONVERT()' and `CAST()'
return `NULL' and produce a warning when the `NO_ZERO_DATE' SQL mode is
enabled.


File: manual.info,  Node: xml-functions,  Next: other-functions,  Prev: cast-functions,  Up: functions

11.10 XML Functions
===================

*Name*                        *Description*
`ExtractValue()'(v5.1.5)      Extracts a value from an XML string using
                              XPath notation
`UpdateXML()'(v5.1.5)         Return replaced XML fragment

This section discusses XML and related functionality in MySQL.

*Note*:

It is possible to obtain XML-formatted output from MySQL in the *Note
`mysql': mysql. and *Note `mysqldump': mysqldump.  clients by invoking
them with the `--xml' option. See *Note mysql::, and *Note mysqldump::.

Two functions providing basic XPath (XML Path Language) capabilities
are available. Some basic information about XPath syntax and usage is
provided later in this section; however, an in-depth discussion of
these topics is beyond the scope of this Manual, and you should refer
to the XML Path Language (XPath) 1.0 standard
(http://www.w3.org/TR/xpath) for definitive information. A useful
resource for those new to XPath or who desire a refresher in the basics
is the Zvon.org XPath Tutorial
(http://www.zvon.org/xxl/XPathTutorial/), which is available in several
languages.

*Note*:

These functions remain under development. We continue to improve these
and other aspects of XML and XPath functionality in MySQL 6.0 and
onwards. You may discuss these, ask questions about them, and obtain
help from other users with them in the MySQL XML User Forum
(http://forums.mysql.com/list.php?44).

XPath expressions used with these functions support user variables and
local stored program variables. User variables are weakly checked;
variables local to stored programs are strongly checked (see also
Bug#26518 (http://bugs.mysql.com/26518)):

   * User variables (weak checking)

     Variables using the syntax `$@VARIABLE_NAME' (that is, user
     variables) are not checked. No warnings or errors are issued by
     the server if a variable has the wrong type or has previously not
     been assigned a value. This also means the user is fully
     responsible for any typographical errors, since no warnings will
     be given if (for example) `$@myvairable' is used where
     `$@myvariable' was intended.

     Example

          mysql> SET @xml = '<a><b>X</b><b>Y</b></a>';
          Query OK, 0 rows affected (0.00 sec)

          mysql> SET @i =1, @j = 2;
          Query OK, 0 rows affected (0.00 sec)

          mysql> SELECT @i, ExtractValue(@xml, '//b[$@i]');
          +------+--------------------------------+
          | @i   | ExtractValue(@xml, '//b[$@i]') |
          +------+--------------------------------+
          |    1 | X                              |
          +------+--------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT @j, ExtractValue(@xml, '//b[$@j]');
          +------+--------------------------------+
          | @j   | ExtractValue(@xml, '//b[$@j]') |
          +------+--------------------------------+
          |    2 | Y                              |
          +------+--------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT @k, ExtractValue(@xml, '//b[$@k]');
          +------+--------------------------------+
          | @k   | ExtractValue(@xml, '//b[$@k]') |
          +------+--------------------------------+
          | NULL |                                |
          +------+--------------------------------+
          1 row in set (0.00 sec)

   * Variables in stored programs (strong checking)

     Variables using the syntax `$VARIABLE_NAME' can be declared and
     used with these functions when they are called inside stored
     programs. Such variables are local to the stored program in which
     they are defined, and are strongly checked for type and value.

     Example

          mysql> DELIMITER |

          mysql> CREATE PROCEDURE myproc ()
              -> BEGIN
              ->   DECLARE i INT DEFAULT 1;
              ->   DECLARE xml VARCHAR(25) DEFAULT '<a>X</a><a>Y</a><a>Z</a>';
              ->
              ->   WHILE i < 4 DO
              ->     SELECT xml, i, ExtractValue(xml, '//a[$i]');
              ->     SET i = i+1;
              ->   END WHILE;
              -> END |
          Query OK, 0 rows affected (0.01 sec)

          mysql> DELIMITER ;

          mysql> CALL myproc;
          +--------------------------+---+------------------------------+
          | xml                      | i | ExtractValue(xml, '//a[$i]') |
          +--------------------------+---+------------------------------+
          | <a>X</a><a>Y</a><a>Z</a> | 1 | X                            |
          +--------------------------+---+------------------------------+
          1 row in set (0.00 sec)

          +--------------------------+---+------------------------------+
          | xml                      | i | ExtractValue(xml, '//a[$i]') |
          +--------------------------+---+------------------------------+
          | <a>X</a><a>Y</a><a>Z</a> | 2 | Y                            |
          +--------------------------+---+------------------------------+
          1 row in set (0.01 sec)

          +--------------------------+---+------------------------------+
          | xml                      | i | ExtractValue(xml, '//a[$i]') |
          +--------------------------+---+------------------------------+
          | <a>X</a><a>Y</a><a>Z</a> | 3 | Z                            |
          +--------------------------+---+------------------------------+
          1 row in set (0.01 sec)

     Parameters

     Variables used in XPath expressions inside stored routines that
     are passed in as parameters are also subject to strong checking.

Expressions containing user variables or variables local to stored
programs must otherwise (except for notation) conform to the rules for
XPath expressions containing variables as given in the XPath 1.0
specification.

*Note*:

Currently, a user variable used to store an XPath expression is treated
as an empty string. Because of this, it is not possible to store an
XPath expression as a user variable. We intend to fix this issue in a
future MySQL release. (Bug#32911 (http://bugs.mysql.com/32911))

   *  `ExtractValue(XML_FRAG, XPATH_EXPR)'

     `ExtractValue()' takes two string arguments, a fragment of XML
     markup XML_FRAG and an XPath expression XPATH_EXPR (also known as a
     _locator_); it returns the text (`CDATA') of the first text node
     which is a child of the element(s) matched by the XPath
     expression. It is the equivalent of performing a match using the
     XPATH_EXPR after appending `/text()'. In other words,
     `ExtractValue('<a><b>Sakila</b></a>', '/a/b')' and
     `ExtractValue('<a><b>Sakila</b></a>', '/a/b/text()')' produce the
     same result.

     If multiple matches are found, then the content of the first child
     text node of each matching element is returned (in the order
     matched) as a single, space-delimited string.

     If no matching text node is found for the expression (including
     the implicit `/text()') -- for whatever reason, as long as
     XPATH_EXPR is valid, and XML_FRAG consists of elements which are
     properly nested and closed -- an empty string is returned. No
     distinction is made between a match on an empty element and no
     match at all. This is by design.

     If you need to determine whether no matching element was found in
     XML_FRAG or such an element was found but contained no child text
     nodes, you should test the result of an expression that uses the
     XPath `count()' function. For example, both of these statements
     return an empty string, as shown here:

          mysql> SELECT ExtractValue('<a><b/></a>', '/a/b');
          +-------------------------------------+
          | ExtractValue('<a><b/></a>', '/a/b') |
          +-------------------------------------+
          |                                     |
          +-------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue('<a><c/></a>', '/a/b');
          +-------------------------------------+
          | ExtractValue('<a><c/></a>', '/a/b') |
          +-------------------------------------+
          |                                     |
          +-------------------------------------+
          1 row in set (0.00 sec)

     However, you can determine whether there was actually a matching
     element using the following:

          mysql> SELECT ExtractValue('<a><b/></a>', 'count(/a/b)');
          +-------------------------------------+
          | ExtractValue('<a><b/></a>', 'count(/a/b)') |
          +-------------------------------------+
          | 1                                   |
          +-------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue('<a><c/></a>', 'count(/a/b)');
          +-------------------------------------+
          | ExtractValue('<a><c/></a>', 'count(/a/b)') |
          +-------------------------------------+
          | 0                                   |
          +-------------------------------------+
          1 row in set (0.01 sec)

     *Important*:

     `ExtractValue()' returns only `CDATA', and does not return any
     tags that might be contained within a matching tag, nor any of
     their content (see the result returned as `val1' in the following
     example).

          mysql> SELECT
              ->   ExtractValue('<a>ccc<b>ddd</b></a>', '/a') AS val1,
              ->   ExtractValue('<a>ccc<b>ddd</b></a>', '/a/b') AS val2,
              ->   ExtractValue('<a>ccc<b>ddd</b></a>', '//b') AS val3,
              ->   ExtractValue('<a>ccc<b>ddd</b></a>', '/b') AS val4,
              ->   ExtractValue('<a>ccc<b>ddd</b><b>eee</b></a>', '//b') AS val5;

          +------+------+------+------+---------+
          | val1 | val2 | val3 | val4 | val5    |
          +------+------+------+------+---------+
          | ccc  | ddd  | ddd  |      | ddd eee |
          +------+------+------+------+---------+

     This function uses the current SQL collation for making
     comparisons with `contains()', performing the same collation
     aggregation as other string functions (such as `CONCAT()'), in
     taking into account the collation coercibility of their arguments;
     see *Note charset-collate-tricky::, for an explanation of the
     rules governing this behavior.

     `NULL' is returned if XML_FRAG contains elements which are not
     properly nested or closed, and a warning is generated, as shown in
     this example:

          mysql> SELECT ExtractValue('<a>c</a><b', '//a');
          +-----------------------------------+
          | ExtractValue('<a>c</a><b', '//a') |
          +-----------------------------------+
          | NULL                              |
          +-----------------------------------+
          1 row in set, 1 warning (0.00 sec)

          mysql> SHOW WARNINGS;
          +---------+------+-------------------------------------------------------------------------------------------+
          | Level   | Code | Message                                                                                   |
          +---------+------+-------------------------------------------------------------------------------------------+
          | Warning | 1523 | Incorrect XML value: 'parse error at line 1 pos 11: END-OF-INPUT unexpected ('>' wanted)' |
          +---------+------+-------------------------------------------------------------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue('<a>c</a><b/>', '//a');
          +-------------------------------------+
          | ExtractValue('<a>c</a><b/>', '//a') |
          +-------------------------------------+
          | c                                   |
          +-------------------------------------+
          1 row in set (0.00 sec)

   *  `UpdateXML(XML_TARGET, XPATH_EXPR, NEW_XML)'

     This function replaces a single portion of a given fragment of XML
     markup XML_TARGET with a new XML fragment NEW_XML, and then
     returns the changed XML. The portion of XML_TARGET that is
     replaced matches an XPath expression XPATH_EXPR supplied by the
     user. If no expression matching XPATH_EXPR is found, or if multiple
     matches are found, the function returns the original XML_TARGET
     XML fragment. All three arguments should be strings.

          mysql> SELECT
              ->   UpdateXML('<a><b>ccc</b><d></d></a>', '/a', '<e>fff</e>') AS val1,
              ->   UpdateXML('<a><b>ccc</b><d></d></a>', '/b', '<e>fff</e>') AS val2,
              ->   UpdateXML('<a><b>ccc</b><d></d></a>', '//b', '<e>fff</e>') AS val3,
              ->   UpdateXML('<a><b>ccc</b><d></d></a>', '/a/d', '<e>fff</e>') AS val4,
              ->   UpdateXML('<a><d></d><b>ccc</b><d></d></a>', '/a/d', '<e>fff</e>') AS val5
              -> \G

          *************************** 1. row ***************************
          val1: <e>fff</e>
          val2: <a><b>ccc</b><d></d></a>
          val3: <a><e>fff</e><d></d></a>
          val4: <a><b>ccc</b><e>fff</e></a>
          val5: <a><d></d><b>ccc</b><d></d></a>

*Note*:

A discussion in depth of XPath syntax and usage are beyond the scope of
this Manual. Please see the XML Path Language (XPath) 1.0 specification
(http://www.w3.org/TR/xpath) for definitive information. A useful
resource for those new to XPath or who are wishing a refresher in the
basics is the Zvon.org XPath Tutorial
(http://www.zvon.org/xxl/XPathTutorial/), which is available in several
languages.

Descriptions and examples of some basic XPath expressions follow:

   * `/TAG'

     Matches `<TAG/>' if and only if `<TAG/>' is the root element.

     Example: `/a' has a match in `<a><b/></a>' because it matches the
     outermost (root) tag. It does not match the inner A element in
     `<b><a/></b>' because in this instance it is the child of another
     element.

   * `/TAG1/TAG2'

     Matches `<TAG2/>' if and only if it is a child of `<TAG1/>', and
     `<TAG1/>' is the root element.

     Example: `/a/b' matches the B element in the XML fragment
     `<a><b/></a>' because it is a child of the root element A. It does
     not have a match in `<b><a/></b>' because in this case, B is the
     root element (and hence the child of no other element). Nor does
     the XPath expression have a match in `<a><c><b/></c></a>'; here, B
     is a descendant of A, but not actually a child of A.

     This construct is extendable to three or more elements. For
     example, the XPath expression `/a/b/c' matches the C element in the
     fragment `<a><b><c/></b></a>'.

   * `//TAG'

     Matches any instance of `<TAG>'.

     Example: `//a' matches the A element in any of the following:
     `<a><b><c/></b></a>'; `<c><a><b/></a></b>'; `<c><b><a/></b></c>'.

     `//' can be combined with `/'. For example, `//a/b' matches the B
     element in either of the fragments `<a><b/></a>' or
     `<a><b><c/></b></a>'

     *Note*:

     `//TAG' is the equivalent of `/descendant-or-self::*/TAG'.  A
     common error is to confuse this with `/descendant-or-self::TAG',
     although the latter expression can actually lead to very different
     results, as can be seen here:

          mysql> SET @xml = '<a><b><c>w</c><b>x</b><d>y</d>z</b></a>';
          Query OK, 0 rows affected (0.00 sec)

          mysql> SELECT @xml;
          +-----------------------------------------+
          | @xml                                    |
          +-----------------------------------------+
          | <a><b><c>w</c><b>x</b><d>y</d>z</b></a> |
          +-----------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue(@xml, '//b[1]');
          +------------------------------+
          | ExtractValue(@xml, '//b[1]') |
          +------------------------------+
          | x z                          |
          +------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue(@xml, '//b[2]');
          +------------------------------+
          | ExtractValue(@xml, '//b[2]') |
          +------------------------------+
          |                              |
          +------------------------------+
          1 row in set (0.01 sec)

          mysql> SELECT ExtractValue(@xml, '/descendant-or-self::*/b[1]');
          +---------------------------------------------------+
          | ExtractValue(@xml, '/descendant-or-self::*/b[1]') |
          +---------------------------------------------------+
          | x z                                               |
          +---------------------------------------------------+
          1 row in set (0.06 sec)

          mysql> SELECT ExtractValue(@xml, '/descendant-or-self::*/b[2]');
          +---------------------------------------------------+
          | ExtractValue(@xml, '/descendant-or-self::*/b[2]') |
          +---------------------------------------------------+
          |                                                   |
          +---------------------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue(@xml, '/descendant-or-self::b[1]');
          +-------------------------------------------------+
          | ExtractValue(@xml, '/descendant-or-self::b[1]') |
          +-------------------------------------------------+
          | z                                               |
          +-------------------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue(@xml, '/descendant-or-self::b[2]');
          +-------------------------------------------------+
          | ExtractValue(@xml, '/descendant-or-self::b[2]') |
          +-------------------------------------------------+
          | x                                               |
          +-------------------------------------------------+
          1 row in set (0.00 sec)

   * The `*' operator acts as a `wildcard' that matches any element.
     For example, the expression `/*/b' matches the B element in either
     of the XML fragments `<a><b/></a>' or `<c><b/></c>'. However, the
     expression does not produce a match in the fragment `<b><a/></b>'
     because B must be a child of some other element. The wildcard may
     be used in any position: The expression `/*/b/*' will match any
     child of a B element that is itself not the root element.

   * You can match any of several locators using the `|' (*Note
     `UNION': union.)  operator. For example, the expression `//b|//c'
     matches all B and C elements in the XML target.

   * It is also possible to match an element based on the value of one
     or more of its attributes. This done using the syntax
     `TAG[@ATTRIBUTE="VALUE"]'.  For example, the expression
     `//b[@id="idB"]' matches the second B element in the fragment
     `<a><b id="idA"/><c/><b id="idB"/></a>'. To match against _any_
     element having `ATTRIBUTE="VALUE"', use the XPath expression
     `//*[ATTRIBUTE="VALUE"]'.

     To filter multiple attribute values, simply use multiple
     attribute-comparison clauses in succession. For example, the
     expression `//b[@c="x"][@d="y"]' matches the element `<b c="x"
     d="y"/>' occurring anywhere in a given XML fragment.

     To find elements for which the same attribute matches any of
     several values, you can use multiple locators joined by the `|'
     operator. For example, to match all B elements whose C attributes
     have either of the values 23 or 17, use the expression
     `//b[@c="23"]|//b[@c="17"]'. You can also use the logical `or'
     operator for this purpose: `//b[@c="23" or @c="17"]'.

     *Note*:

     The difference between `or' and `|' is that `or' joins conditions,
     while `|' joins result sets.

XPath Limitations

The XPath syntax supported by these functions is currently subject to
the following limitations:

   * Nodeset-to-nodeset comparison (such as `'/a/b[@c=@d]'') is not
     supported.

   * All of the standard XPath comparison operators are supported.

   * Relative locator expressions are resolved in the context of the
     root node. For example, consider the following query and result:

          mysql> SELECT ExtractValue(
              ->   '<a><b c="1">X</b><b c="2">Y</b></a>',
              ->    'a/b'
              -> ) AS result;
          +--------+
          | result |
          +--------+
          | X Y    |
          +--------+
          1 row in set (0.03 sec)

     In this case, the locator `a/b' resolves to `/a/b'.

     Relative locators are also supported within predicates. In the
     following example, `d[../@c="1"]' is resolved as `/a/b[@c="1"]/d':

          mysql> SELECT ExtractValue(
              ->      '<a>
              ->        <b c="1"><d>X</d></b>
              ->        <b c="2"><d>X</d></b>
              ->      </a>',
              ->      'a/b/d[../@c="1"]')
              -> AS result;
          +--------+
          | result |
          +--------+
          | X      |
          +--------+
          1 row in set (0.00 sec)

   * Locators prefixed with expressions that evaluate as scalar values
     -- including variable references, literals, numbers,and scalar
     function calls -- are not supported. Beginning with MySQL 6.0.10,
     they are disallowed, and their use results in an error. (Bug#42495
     (http://bugs.mysql.com/42495))

   * The `::' operator is not supported in combination with node types
     such as the following:

        * `AXIS::comment()'

        * `AXIS::text()'

        * `AXIS::processing-instructions()'

        * `AXIS::node()'

     However, name tests (such as `AXIS::NAME' and `AXIS::*') are
     supported, as shown in these examples:

          mysql> SELECT ExtractValue('<a><b>x</b><c>y</c></a>','/a/child::b');
          +-------------------------------------------------------+
          | ExtractValue('<a><b>x</b><c>y</c></a>','/a/child::b') |
          +-------------------------------------------------------+
          | x                                                     |
          +-------------------------------------------------------+
          1 row in set (0.02 sec)

          mysql> SELECT ExtractValue('<a><b>x</b><c>y</c></a>','/a/child::*');
          +-------------------------------------------------------+
          | ExtractValue('<a><b>x</b><c>y</c></a>','/a/child::*') |
          +-------------------------------------------------------+
          | x y                                                   |
          +-------------------------------------------------------+
          1 row in set (0.01 sec)

   * `Up-and-down' navigation is not supported in cases where the path
     would lead `above' the root element. That is, you cannot use
     expressions which match on descendants of ancestors of a given
     element, where one or more of the ancestors of the current element
     is also an ancestor of the root element (see Bug#16321
     (http://bugs.mysql.com/16321)).

   * The following XPath functions are not supported, or have known
     issues as indicated:

        * Prior to MySQL 6.0.7, the `boolean()' function did not
          produce correct results for some string and nodeset values,
          including the `NULL' string (see Bug#26051
          (http://bugs.mysql.com/26051)).

        * `id()'

        * `lang()'

        * `local-name()'

        * `name()'

        * `namespace-uri()'

        * `normalize-space()'

        * `starts-with()'

        * `string()'

        * `substring-after()'

        * `substring-before()'

        * `translate()'

   * The following axes are not supported:

        * `following-sibling'

        * `following'

        * `preceding-sibling'

        * `preceding'

XPath expressions passed as arguments to `ExtractValue()' and
`UpdateXML()' may contain the colon character (``:'') in element
selectors, which enables their use with markup employing XML namespaces
notation. For example:

     mysql> SET @xml = '<a>111<b:c>222<d>333</d><e:f>444</e:f></b:c></a>';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT ExtractValue(@xml, '//e:f');
     +-----------------------------+
     | ExtractValue(@xml, '//e:f') |
     +-----------------------------+
     | 444                         |
     +-----------------------------+
     1 row in set (0.00 sec)

     mysql> SELECT UpdateXML(@xml, '//b:c', '<g:h>555</g:h>');
     +--------------------------------------------+
     | UpdateXML(@xml, '//b:c', '<g:h>555</g:h>') |
     +--------------------------------------------+
     | <a>111<g:h>555</g:h></a>                   |
     +--------------------------------------------+
     1 row in set (0.00 sec)

This is similar in some respects to what is allowed by Apache Xalan
(http://xalan.apache.org/) and some other parsers, and is much simpler
than requiring namespace declarations or the use of the
`namespace-uri()' and `local-name()' functions.

Error handling

For both `ExtractValue()' and `UpdateXML()', the XPath locator used
must be valid and the XML to be searched must consist of elements which
are properly nested and closed. If the locator is invalid, an error is
generated:

     mysql> SELECT ExtractValue('<a>c</a><b/>', '/&a');
     `ERROR 1105 (HY000): XPATH syntax error: '&a''

If XML_FRAG does not consist of elements which are properly nested and
closed, then `NULL' is returned, and a warning is generated, as shown
in this example:

     mysql> SELECT ExtractValue('<a>c</a><b', '//a');
     +-----------------------------------+
     | ExtractValue('<a>c</a><b', '//a') |
     +-----------------------------------+
     | NULL                              |
     +-----------------------------------+
     1 row in set, 1 warning (0.00 sec)

     mysql> SHOW WARNINGS;
     +---------+------+-------------------------------------------------------------------------------------------+
     | Level   | Code | Message                                                                                   |
     +---------+------+-------------------------------------------------------------------------------------------+
     | Warning | 1523 | Incorrect XML value: 'parse error at line 1 pos 11: END-OF-INPUT unexpected ('>' wanted)' |
     +---------+------+-------------------------------------------------------------------------------------------+
     1 row in set (0.00 sec)

     mysql> SELECT ExtractValue('<a>c</a><b/>', '//a');
     +-------------------------------------+
     | ExtractValue('<a>c</a><b/>', '//a') |
     +-------------------------------------+
     | c                                   |
     +-------------------------------------+
     1 row in set (0.00 sec)

*Important*:

The replacement XML used as the third argument to `UpdateXML()' is
_not_ checked to determine whether it consists solely of elements which
are properly nested and closed.

XPath Injection

_code injection_ occurs when malicious code is introduced into the
system to gain unauthorized access to privileges and data. It is based
on exploiting assumptions made by developers about the type and content
of data input from users. XPath is no exception in this regard.

A common scenario in which this can happen is the case of application
which handles authorization by matching the combination of a login name
and password with those found in an XML file, using an XPath expression
like this one:

     //user[login/text()='neapolitan' and password/text()='1c3cr34m']/attribute::id

This is the XPath equivalent of an SQL statement like this one:

     SELECT id FROM users WHERE login='neapolitan' AND password='1c3cr34m';

A PHP application employing XPath might handle the login process like
this:

     <?php

       $file     =   "users.xml";

       $login    =   $POST["login"];
       $password =   $POST["password"];

       $xpath = "//user[login/text()=$login and password/text()=$password]/attribute::id";

       if( file_exists($file) )
       {
         $xml = simplexml_load_file($file);

         if($result = $xml->xpath($xpath))
           echo "You are now logged in as user $result[0].";
         else
           echo "Invalid login name or password.";
       }
       else
         exit("Failed to open $file.");

     ?>

No checks are performed on the input. This means that a malevolent user
can `short-circuit' the test by entering `' or 1=1' for both the login
name and password, resulting in $xpath being evaluated as shown here:

     //user[login/text()='' or 1=1 and password/text()='' or 1=1]/attribute::id

Since the expression inside the square brackets always evaluates as
`true', it is effectively the same as this one, which matches the `id'
attribute of every `user' element in the XML document:

     //user/attribute::id

One way in which this particular attack can be circumvented is simply
by quoting the variable names to be interpolated in the definition of
`$xpath', forcing the values passed from a Web form to be converted to
strings:

     $xpath = "//user[login/text()='$login' and password/text()='$password']/attribute::id";

This is the same strategy that is often recommended for preventing SQL
injection attacks. In general, the practices you should follow for
preventing XPath injection attacks are the same as for preventing SQL
injection:

   * Never accepted untested data from users in your application.

   * Check all user-submited data for type; reject or convert data that
     is of the wrong type

   * Test numerical data for out of range values; truncate, round, or
     reject values that are out of range. Test strings for illegal
     characters and either strip them out or reject input containing
     them.

   * Do not output explicit error messages that might provide an
     unauthorized user with clues that could be used to compromise the
     system; log these to a file or database table instead.

Just as SQL injection attacks can be used to obtain information about
database schemas, so can XPath injection be used to traverse XML files
to uncover their structure, as discussed in Amit Klein's paper Blind
XPath Injection
(http://www.packetstormsecurity.org/papers/bypass/Blind_XPath_Injection_20040518.pdf)
(PDF file, 46KB).

It is also important to check the output being sent back to the client.
Consider what can happen when we use the MySQL `ExtractValue()'
function:

     mysql> SELECT ExtractValue(
         ->     LOAD_FILE('users.xml'),
         ->     '//user[login/text()="" or 1=1 and password/text()="" or 1=1]/attribute::id'
         -> ) AS id;
     +-------------------------------+
     | id                            |
     +-------------------------------+
     | 00327 13579 02403 42354 28570 |
     +-------------------------------+
     1 row in set (0.01 sec)

Because `ExtractValue()' returns multiple matches as a single
space-delimited string, this injection attack provides every valid ID
contained within `users.xml' to the user as a single row of output. As
an extra safeguard, you should also test output before returning it to
the user. Here is a simple example:

     mysql> SELECT @id = ExtractValue(
         ->     LOAD_FILE('users.xml'),
         ->     '//user[login/text()="" or 1=1 and password/text()="" or 1=1]/attribute::id'
         -> );
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT IF(
         ->     INSTR(@id, ' ') = 0,
         ->     @id,
         ->     'Unable to retrieve user ID')
         -> AS singleID;
     +----------------------------+
     | singleID                   |
     +----------------------------+
     | Unable to retrieve user ID |
     +----------------------------+
     1 row in set (0.00 sec)

In general, the guidelines for returning data to users securely are the
same as for accepting user input. These can be summed up as:

   * Always test outgoing data for type and allowable values.

   * Never allow unauthorized users to view error messages that might
     provide information about the application that could be used to
     exploit it.


File: manual.info,  Node: other-functions,  Next: group-by-functions-and-modifiers,  Prev: xml-functions,  Up: functions

11.11 Other Functions
=====================

* Menu:

* bit-functions::                Bit Functions
* encryption-functions::         Encryption and Compression Functions
* information-functions::        Information Functions
* miscellaneous-functions::      Miscellaneous Functions

*Name*                        *Description*
`AES_DECRYPT()'               Decrypt using AES
`AES_ENCRYPT()'               Encrypt using AES
`BENCHMARK()'                 Repeatedly execute an expression
`BIT_COUNT()'                 Return the number of bits that are set
`&'                           Bitwise AND
`~'                           Invert bits
`|'                           Bitwise OR
`^'                           Bitwise XOR
`CHARSET()'(v4.1.0)           Return the character set of the argument
`COERCIBILITY()'(v4.1.1)      Return the collation coercibility value of
                              the string  argument
`COLLATION()'(v4.1.0)         Return the collation of the string argument
`COMPRESS()'(v4.1.1)          Return result as a binary string
`CONNECTION_ID()'             Return the connection ID (thread ID)   for
                              the connection
`CURRENT_USER()',             Return the user name and host name
`CURRENT_USER'                combination
`DATABASE()'                  Return the default (current) database name
`DECODE()'                    Decodes a string encrypted using ENCODE()
`DEFAULT()'                   Return the default value for a table column
`DES_DECRYPT()'               Decrypt a string
`DES_ENCRYPT()'               Encrypt a string
`ENCODE()'                    Encode a string
`ENCRYPT()'                   Encrypt a string
`FOUND_ROWS()'                For a SELECT with a LIMIT clause, the
                              number of rows that would be returned were
                              there no LIMIT clause
`GET_LOCK()'                  Get a named lock
`INET_ATON()'                 Return the numeric value of an IP address
`INET_NTOA()'                 Return the IP address from a numeric value
`IS_FREE_LOCK()'              Checks whether the named lock  is free
`IS_USED_LOCK()'(v4.1.0)      Checks whether the named lock is in use.
                              Return connection identifier if true.
`LAST_INSERT_ID()'            Value of the AUTOINCREMENT column   for
                              the last INSERT
`<<'                          Left shift
`MASTER_POS_WAIT()'           Block until the slave has read and
                              applied all updates up to the specified
                              position
`MD5()'                       Calculate MD5 checksum
`NAME_CONST()'(v5.0.12)       Causes the column to have the given name
`OLD_PASSWORD()'(v4.1)        Return the value of the  old (pre-4.1)
                              implementation of PASSWORD
`PASSWORD()'                  Calculate and return a password string
`RAND()'                      Return a random floating-point value
`RELEASE_LOCK()'              Releases the named lock
`>>'                          Right shift
`ROW_COUNT()'(v5.0.1)         The number of rows  updated
`SCHEMA()'(v5.0.2)            A synonym for DATABASE()
`SESSION_USER()'              Synonym for USER()
`SHA1()', `SHA()'             Calculate an SHA-1 160-bit checksum
`SHA2()'(v6.0.5)              Calculate an SHA-2 checksum
`SLEEP()'(v5.0.12)            Sleep for a number of seconds
`SYSTEM_USER()'               Synonym for USER()
`UNCOMPRESS()'(v4.1.1)        Uncompress a string compressed
`UNCOMPRESSED_LENGTH()'(v4.1.1)Return the length of a string before
                              compression
`USER()'                      Return the current user name and host name
`UUID_SHORT()'(v5.1.20)       Return an integer-valued universal
                              identifier
`UUID()'(v4.1.2)              Return a Universal Unique Identifier (UUID)
`VALUES()'(v4.1.1)            Defines the values to be used during an
                              INSERT
`VERSION()'                   Returns a string that indicates the MySQL
                              server version


File: manual.info,  Node: bit-functions,  Next: encryption-functions,  Prev: other-functions,  Up: other-functions

11.11.1 Bit Functions
---------------------

*Name*                        *Description*
`BIT_COUNT()'                 Return the number of bits that are set
`&'                           Bitwise AND
`~'                           Invert bits
`|'                           Bitwise OR
`^'                           Bitwise XOR
`<<'                          Left shift
`>>'                          Right shift

MySQL uses *Note `BIGINT': numeric-types. (64-bit) arithmetic for bit
operations, so these operators have a maximum range of 64 bits.

   *  `|'

     Bitwise OR:

          mysql> SELECT 29 | 15;
                  -> 31

     The result is an unsigned 64-bit integer.

   *  `&'

     Bitwise AND:

          mysql> SELECT 29 & 15;
                  -> 13

     The result is an unsigned 64-bit integer.

   *  `^'

     Bitwise XOR:

          mysql> SELECT 1 ^ 1;
                  -> 0
          mysql> SELECT 1 ^ 0;
                  -> 1
          mysql> SELECT 11 ^ 3;
                  -> 8

     The result is an unsigned 64-bit integer.

   *  `<<'

     Shifts a longlong (*Note `BIGINT': numeric-types.)  number to the
     left.

          mysql> SELECT 1 << 2;
                  -> 4

     The result is an unsigned 64-bit integer. The value is truncated
     to 64 bits. In particular, if the shift count is greater or equal
     to the width of an unsigned 64-bit number, the result is zero.

   *  `>>'

     Shifts a longlong (*Note `BIGINT': numeric-types.)  number to the
     right.

          mysql> SELECT 4 >> 2;
                  -> 1

     The result is an unsigned 64-bit integer. The value is truncated
     to 64 bits. In particular, if the shift count is greater or equal
     to the width of an unsigned 64-bit number, the result is zero.

   *  `~'

     Invert all bits.

          mysql> SELECT 5 & ~1;
                  -> 4

     The result is an unsigned 64-bit integer.

   *  `BIT_COUNT(N)'

     Returns the number of bits that are set in the argument N.

          mysql> SELECT BIT_COUNT(29), BIT_COUNT(b'101010');
                  -> 4, 3


File: manual.info,  Node: encryption-functions,  Next: information-functions,  Prev: bit-functions,  Up: other-functions

11.11.2 Encryption and Compression Functions
--------------------------------------------

*Name*                        *Description*
`AES_DECRYPT()'               Decrypt using AES
`AES_ENCRYPT()'               Encrypt using AES
`COMPRESS()'(v4.1.1)          Return result as a binary string
`DECODE()'                    Decodes a string encrypted using ENCODE()
`DES_DECRYPT()'               Decrypt a string
`DES_ENCRYPT()'               Encrypt a string
`ENCODE()'                    Encode a string
`ENCRYPT()'                   Encrypt a string
`MD5()'                       Calculate MD5 checksum
`OLD_PASSWORD()'(v4.1)        Return the value of the  old (pre-4.1)
                              implementation of PASSWORD
`PASSWORD()'                  Calculate and return a password string
`SHA1()', `SHA()'             Calculate an SHA-1 160-bit checksum
`SHA2()'(v6.0.5)              Calculate an SHA-2 checksum
`UNCOMPRESS()'(v4.1.1)        Uncompress a string compressed
`UNCOMPRESSED_LENGTH()'(v4.1.1)Return the length of a string before
                              compression

*Note*:

The encryption and compression functions return binary strings. For
many of these functions, the result might contain arbitrary byte
values. If you want to store these results, use a column with a *Note
`VARBINARY': binary-varbinary. or *Note `BLOB': blob. binary string
data type.  This will avoid potential problems with trailing space
removal or character set conversion that would change data values, such
as may occur if you use a non-binary string data type (*Note `CHAR':
char, *Note `VARCHAR': char, *Note `TEXT': blob.).

*Note*:

Exploits for the MD5 and SHA-1 algorithms have become known.  You may
wish to consider using one of the other encryption functions described
in this section instead, such as `SHA2()'.

   *  `AES_DECRYPT(CRYPT_STR,KEY_STR)'

     This function allows decryption of data using the official AES
     (Advanced Encryption Standard) algorithm. For more information,
     see the description of `AES_ENCRYPT()'.

   *  `AES_ENCRYPT(STR,KEY_STR)'

     `AES_ENCRYPT()' and `AES_DECRYPT()' allow encryption and
     decryption of data using the official AES (Advanced Encryption
     Standard) algorithm, previously known as `Rijndael.' Encoding with
     a 128-bit key length is used, but you can extend it up to 256 bits
     by modifying the source. We chose 128 bits because it is much
     faster and it is secure enough for most purposes.

     `AES_ENCRYPT()' encrypts a string and returns a binary string.
     `AES_DECRYPT()' decrypts the encrypted string and returns the
     original string. The input arguments may be any length. If either
     argument is `NULL', the result of this function is also `NULL'.

     Because AES is a block-level algorithm, padding is used to encode
     uneven length strings and so the result string length may be
     calculated using this formula:

          16 x (trunc(STRING_LENGTH / 16) + 1)

     If `AES_DECRYPT()' detects invalid data or incorrect padding, it
     returns `NULL'. However, it is possible for `AES_DECRYPT()' to
     return a non-`NULL' value (possibly garbage) if the input data or
     the key is invalid.

     You can use the AES functions to store data in an encrypted form
     by modifying your queries:

          INSERT INTO t VALUES (1,AES_ENCRYPT('text','password'));

     `AES_ENCRYPT()' and `AES_DECRYPT()' can be considered the most
     cryptographically secure encryption functions currently available
     in MySQL.

   *  `COMPRESS(STRING_TO_COMPRESS)'

     Compresses a string and returns the result as a binary string.
     This function requires MySQL to have been compiled with a
     compression library such as `zlib'.  Otherwise, the return value
     is always `NULL'. The compressed string can be uncompressed with
     `UNCOMPRESS()'.

          mysql> SELECT LENGTH(COMPRESS(REPEAT('a',1000)));
                  -> 21
          mysql> SELECT LENGTH(COMPRESS(''));
                  -> 0
          mysql> SELECT LENGTH(COMPRESS('a'));
                  -> 13
          mysql> SELECT LENGTH(COMPRESS(REPEAT('a',16)));
                  -> 15

     The compressed string contents are stored the following way:

        * Empty strings are stored as empty strings.

        * Non-empty strings are stored as a four-byte length of the
          uncompressed string (low byte first), followed by the
          compressed string. If the string ends with space, an extra
          ``.'' character is added to avoid problems with endspace
          trimming should the result be stored in a *Note `CHAR': char.
          or *Note `VARCHAR': char. column. (However, use of non-binary
          string data types such as *Note `CHAR': char. or *Note
          `VARCHAR': char. to store compressed strings is not
          recommended anyway because character set conversion may
          occur. Use a *Note `VARBINARY': binary-varbinary. or *Note
          `BLOB': blob. binary string column instead.)

   *  `DECODE(CRYPT_STR,PASS_STR)'

     Decrypts the encrypted string CRYPT_STR using PASS_STR as the
     password.  CRYPT_STR should be a string returned from `ENCODE()'.

   *  `ENCODE(STR,PASS_STR)'

     Encrypt STR using PASS_STR as the password. To decrypt the result,
     use `DECODE()'.

     The result is a binary string of the same length as STR.

     The strength of the encryption is based on how good the random
     generator is. It should suffice for short strings.

   *  `DES_DECRYPT(CRYPT_STR[,KEY_STR])'

     Decrypts a string encrypted with `DES_ENCRYPT()'. If an error
     occurs, this function returns `NULL'.

     This function works only if MySQL has been configured with SSL
     support. See *Note secure-connections::.

     If no KEY_STR argument is given, `DES_DECRYPT()' examines the
     first byte of the encrypted string to determine the DES key number
     that was used to encrypt the original string, and then reads the
     key from the DES key file to decrypt the message. For this to
     work, the user must have the `SUPER' privilege. The key file can
     be specified with the `--des-key-file' server option.

     If you pass this function a KEY_STR argument, that string is used
     as the key for decrypting the message.

     If the CRYPT_STR argument does not appear to be an encrypted
     string, MySQL returns the given CRYPT_STR.

   *  `DES_ENCRYPT(STR[,{KEY_NUM|KEY_STR}])'

     Encrypts the string with the given key using the Triple-DES
     algorithm.

     This function works only if MySQL has been configured with SSL
     support. See *Note secure-connections::.

     The encryption key to use is chosen based on the second argument
     to `DES_ENCRYPT()', if one was given. With no argument, the first
     key from the DES key file is used. With a KEY_NUM argument, the
     given key number (0-9) from the DES key file is used. With a
     KEY_STR argument, the given key string is used to encrypt STR.

     The key file can be specified with the `--des-key-file' server
     option.

     The return string is a binary string where the first character is
     `CHAR(128 | KEY_NUM)'. If an error occurs, `DES_ENCRYPT()' returns
     `NULL'.

     The 128 is added to make it easier to recognize an encrypted key.
     If you use a string key, KEY_NUM is 127.

     The string length for the result is given by this formula:

          NEW_LEN = ORIG_LEN + (8 - (ORIG_LEN % 8)) + 1

     Each line in the DES key file has the following format:

          KEY_NUM DES_KEY_STR

     Each KEY_NUM value must be a number in the range from `0' to `9'.
     Lines in the file may be in any order.  DES_KEY_STR is the string
     that is used to encrypt the message. There should be at least one
     space between the number and the key. The first key is the default
     key that is used if you do not specify any key argument to
     `DES_ENCRYPT()'.

     You can tell MySQL to read new key values from the key file with
     the *Note `FLUSH DES_KEY_FILE': flush. statement. This requires the
     `RELOAD' privilege.

     One benefit of having a set of default keys is that it gives
     applications a way to check for the existence of encrypted column
     values, without giving the end user the right to decrypt those
     values.

          mysql> SELECT customer_address FROM customer_table
               > WHERE crypted_credit_card = DES_ENCRYPT('credit_card_number');

   *  `ENCRYPT(STR[,SALT])'

     Encrypts STR using the Unix `crypt()' system call and returns a
     binary string. The SALT argument should be a string with at least
     two characters. If no SALT argument is given, a random value is
     used.

          mysql> SELECT ENCRYPT('hello');
                  -> 'VxuFAJXVARROc'

     `ENCRYPT()' ignores all but the first eight characters of STR, at
     least on some systems. This behavior is determined by the
     implementation of the underlying `crypt()' system call.

     The use of `ENCRYPT()' with multi-byte character sets other than
     `utf8' or `utf8mb3' is not recommended because the system call
     expects a string terminated by a zero byte.

     If `crypt()' is not available on your system (as is the case with
     Windows), `ENCRYPT()' always returns `NULL'.

   *  `MD5(STR)'

     Calculates an MD5 128-bit checksum for the string. The value is
     returned as a binary string of 32 hex digits, or `NULL' if the
     argument was `NULL'. The return value can, for example, be used as
     a hash key.

          mysql> SELECT MD5('testing');
                  -> 'ae2b1fca515949e5d54fb22b8ed95575'

     This is the `RSA Data Security, Inc. MD5 Message-Digest Algorithm.'

     If you want to convert the value to uppercase, see the description
     of binary string conversion given in the entry for the `BINARY'
     operator in *Note cast-functions::.

     See the note regarding the MD5 algorithm at the beginning this
     section.

   *  `OLD_PASSWORD(STR)'

     `OLD_PASSWORD()' was added to MySQL when the implementation of
     `PASSWORD()' was changed to improve security.  `OLD_PASSWORD()'
     returns the value of the old (pre-4.1) implementation of
     `PASSWORD()' as a binary string, and is intended to permit you to
     reset passwords for any pre-4.1 clients that need to connect to
     your version 6.0 MySQL server without locking them out. See *Note
     password-hashing::.

   *  `PASSWORD(STR)'

     Calculates and returns a password string from the plaintext
     password STR and returns a binary string, or `NULL' if the
     argument was `NULL'. This is the function that is used for
     encrypting MySQL passwords for storage in the `Password' column of
     the `user' grant table.

          mysql> SELECT PASSWORD('badpwd');
                  -> '*AAB3E285149C0135D51A520E1940DD3263DC008C'

     `PASSWORD()' encryption is one-way (not reversible).

     `PASSWORD()' does not perform password encryption in the same way
     that Unix passwords are encrypted. See `ENCRYPT()'.

     *Note*:

     The `PASSWORD()' function is used by the authentication system in
     MySQL Server; you should _not_ use it in your own applications.
     For that purpose, consider `MD5()' or `SHA1()' instead. Also see
     section 2 (Challenge-Response Authentication Mechanism (CRAM)),
     for more information about handling passwords and authentication
     securely in your applications.

   *  `SHA1(STR)', `SHA(STR)'

     Calculates an SHA-1 160-bit checksum for the string, as described
     in RFC 3174 (Secure Hash Algorithm). The value is returned as a
     binary string of 40 hex digits, or `NULL' if the argument was
     `NULL'. One of the possible uses for this function is as a hash
     key. You can also use it as a cryptographic function for storing
     passwords.  `SHA()' is synonymous with `SHA1()'.

          mysql> SELECT SHA1('abc');
                  -> 'a9993e364706816aba3e25717850c26c9cd0d89d'

     `SHA1()' can be considered a cryptographically more secure
     equivalent of `MD5()'. However, see the note regarding the MD5 and
     SHA-1 algorithms at the beginning this section.

   *  `SHA2(STR, HASH_LENGTH)'

     Calculates the SHA-2 family of hash functions (SHA-224, SHA-256,
     SHA-384, and SHA-512). The first argument is the cleartext string
     to be hashed. The second argument indicates the desired bit length
     of the result, which must have a value of 224, 256, 384, or 512.
     If either argument is `NULL' or the hash length is not one of the
     allowed values, the return value is `NULL'.  Otherwise, the
     function result is a hash value containing the desired number of
     bits, returned as a binary string of hex digits.

          mysql> SELECT SHA2('abc', 224);
                  -> '23097d223405d8228642a477bda255b32aadbce4bda0b3f7e36c9da7'

     This function works only if MySQL has been configured with SSL
     support. See *Note secure-connections::.

     `SHA2()' can be considered cryptographically more secure than
     `MD5()' or `SHA1()'.

     `SHA2()' was added in MySQL 6.0.5.

   *  `UNCOMPRESS(STRING_TO_UNCOMPRESS)'

     Uncompresses a string compressed by the `COMPRESS()' function. If
     the argument is not a compressed value, the result is `NULL'. This
     function requires MySQL to have been compiled with a compression
     library such as `zlib'. Otherwise, the return value is always
     `NULL'.

          mysql> SELECT UNCOMPRESS(COMPRESS('any string'));
                  -> 'any string'
          mysql> SELECT UNCOMPRESS('any string');
                  -> NULL

   *  `UNCOMPRESSED_LENGTH(COMPRESSED_STRING)'

     Returns the length that the compressed string had before being
     compressed.

          mysql> SELECT UNCOMPRESSED_LENGTH(COMPRESS(REPEAT('a',30)));
                  -> 30


File: manual.info,  Node: information-functions,  Next: miscellaneous-functions,  Prev: encryption-functions,  Up: other-functions

11.11.3 Information Functions
-----------------------------

*Name*                        *Description*
`BENCHMARK()'                 Repeatedly execute an expression
`CHARSET()'(v4.1.0)           Return the character set of the argument
`COERCIBILITY()'(v4.1.1)      Return the collation coercibility value of
                              the string  argument
`COLLATION()'(v4.1.0)         Return the collation of the string argument
`CONNECTION_ID()'             Return the connection ID (thread ID)   for
                              the connection
`CURRENT_USER()',             Return the user name and host name
`CURRENT_USER'                combination
`DATABASE()'                  Return the default (current) database name
`FOUND_ROWS()'                For a SELECT with a LIMIT clause, the
                              number of rows that would be returned were
                              there no LIMIT clause
`LAST_INSERT_ID()'            Value of the AUTOINCREMENT column   for
                              the last INSERT
`ROW_COUNT()'(v5.0.1)         The number of rows  updated
`SCHEMA()'(v5.0.2)            A synonym for DATABASE()
`SESSION_USER()'              Synonym for USER()
`SYSTEM_USER()'               Synonym for USER()
`USER()'                      Return the current user name and host name
`VERSION()'                   Returns a string that indicates the MySQL
                              server version

   *  `BENCHMARK(COUNT,EXPR)'

     The `BENCHMARK()' function executes the expression EXPR repeatedly
     COUNT times. It may be used to time how quickly MySQL processes
     the expression. The result value is always `0'. The intended use
     is from within the *Note `mysql': mysql. client, which reports
     query execution times:

          mysql> SELECT BENCHMARK(1000000,ENCODE('hello','goodbye'));
          +----------------------------------------------+
          | BENCHMARK(1000000,ENCODE('hello','goodbye')) |
          +----------------------------------------------+
          |                                            0 |
          +----------------------------------------------+
          1 row in set (4.74 sec)

     The time reported is elapsed time on the client end, not CPU time
     on the server end. It is advisable to execute `BENCHMARK()'
     several times, and to interpret the result with regard to how
     heavily loaded the server machine is.

     `BENCHMARK()' is intended for measuring the runtime performance of
     scalar expressions, which has some significant implications for
     the way that you use it and interpret the results:

        * Only scalar expressions can be used. Although the expression
          can be a subquery, it must return a single column and at most
          a single row. For example, `BENCHMARK(10, (SELECT * FROM t))'
          will fail if the table `t' has more than one column or more
          than one row.

        * Executing a `SELECT EXPR' statement N times differs from
          executing `SELECT BENCHMARK(N, EXPR)' in terms of the amount
          of overhead involved. The two have very different execution
          profiles and you should not expect them to take the same
          amount of time. The former involves the parser, optimizer,
          table locking, and runtime evaluation N times each. The
          latter involves only runtime evaluation N times, and all the
          other components just once. Memory structures already
          allocated are reused, and runtime optimizations such as local
          caching of results already evaluated for aggregate functions
          can alter the results. Use of `BENCHMARK()' thus measures
          performance of the runtime component by giving more weight to
          that component and removing the `noise' introduced by the
          network, parser, optimizer, and so forth.

   *  `CHARSET(STR)'

     Returns the character set of the string argument.

          mysql> SELECT CHARSET('abc');
                  -> 'latin1'
          mysql> SELECT CHARSET(CONVERT('abc' USING utf8));
                  -> 'utf8'
          mysql> SELECT CHARSET(USER());
                  -> 'utf8'

   *  `COERCIBILITY(STR)'

     Returns the collation coercibility value of the string argument.

          mysql> SELECT COERCIBILITY('abc' COLLATE latin1_swedish_ci);
                  -> 0
          mysql> SELECT COERCIBILITY(USER());
                  -> 3
          mysql> SELECT COERCIBILITY('abc');
                  -> 4

     The return values have the meanings shown in the following table.
     Lower values have higher precedence.

     *Coercibility**Meaning*  *Example*
     `0'        Explicit   Value with `COLLATE' clause
                collation  
     `1'        No         Concatenation of strings with different
                collation  collations
     `2'        Implicit   Column value, stored routine parameter or
                collation  local variable
     `3'        System     `USER()' return value
                constant   
     `4'        Coercible  Literal string
     `5'        Ignorable  `NULL' or an expression derived from `NULL'

   *  `COLLATION(STR)'

     Returns the collation of the string argument.

          mysql> SELECT COLLATION('abc');
                  -> 'latin1_swedish_ci'
          mysql> SELECT COLLATION(_utf8'abc');
                  -> 'utf8_general_ci'

   *  `CONNECTION_ID()'

     Returns the connection ID (thread ID) for the connection.  Every
     connection has an ID that is unique among the set of currently
     connected clients.

          mysql> SELECT CONNECTION_ID();
                  -> 23786

   *  `CURRENT_USER', `CURRENT_USER()'

     Returns the user name and host name combination for the MySQL
     account that the server used to authenticate the current client.
     This account determines your access privileges. The return value
     is a string in the `utf8' character set.

     The value of `CURRENT_USER()' can differ from the value of
     `USER()'.

          mysql> SELECT USER();
                  -> 'davida@localhost'
          mysql> SELECT * FROM mysql.user;
          ERROR 1044: Access denied for user ''@'localhost' to
          database 'mysql'
          mysql> SELECT CURRENT_USER();
                  -> '@localhost'

     The example illustrates that although the client specified a user
     name of `davida' (as indicated by the value of the `USER()'
     function), the server authenticated the client using an anonymous
     user account (as seen by the empty user name part of the
     `CURRENT_USER()' value).  One way this might occur is that there
     is no account listed in the grant tables for `davida'.

     Within a stored program or view, `CURRENT_USER()' returns the
     account for the user who defined the object (as given by its
     `DEFINER' value). For stored procedures and functions and views
     defined with the `SQL SECURITY INVOKER' characteristic,
     `CURRENT_USER()' returns the object's invoker.

   *  `DATABASE()'

     Returns the default (current) database name as a string in the
     `utf8' character set. If there is no default database, `DATABASE()'
     returns `NULL'. Within a stored routine, the default database is
     the database that the routine is associated with, which is not
     necessarily the same as the database that is the default in the
     calling context.

          mysql> SELECT DATABASE();
                  -> 'test'

     If there is no default database, `DATABASE()' returns `NULL'.

   *  `FOUND_ROWS()'

     A *Note `SELECT': select. statement may include a `LIMIT' clause
     to restrict the number of rows the server returns to the client.
     In some cases, it is desirable to know how many rows the statement
     would have returned without the `LIMIT', but without running the
     statement again. To obtain this row count, include a
     `SQL_CALC_FOUND_ROWS' option in the *Note `SELECT': select.
     statement, and then invoke `FOUND_ROWS()' afterward:

          mysql> SELECT SQL_CALC_FOUND_ROWS * FROM TBL_NAME
              -> WHERE id > 100 LIMIT 10;
          mysql> SELECT FOUND_ROWS();

     The second *Note `SELECT': select. returns a number indicating how
     many rows the first *Note `SELECT': select. would have returned
     had it been written without the `LIMIT' clause.

     In the absence of the `SQL_CALC_FOUND_ROWS' option in the most
     recent successful *Note `SELECT': select. statement,
     `FOUND_ROWS()' returns the number of rows in the result set
     returned by that statement.  If the statement includes a `LIMIT'
     clause, `FOUND_ROWS()' returns the number of rows up to the limit.
     For example, `FOUND_ROWS()' returns 10 or 60, respectively, if the
     statement includes `LIMIT 10' or `LIMIT 50, 10'.

     The row count available through `FOUND_ROWS()' is transient and
     not intended to be available past the statement following the
     `SELECT SQL_CALC_FOUND_ROWS' statement.  If you need to refer to
     the value later, save it:

          mysql> SELECT SQL_CALC_FOUND_ROWS * FROM ... ;
          mysql> SET @rows = FOUND_ROWS();

     If you are using `SELECT SQL_CALC_FOUND_ROWS', MySQL must
     calculate how many rows are in the full result set. However, this
     is faster than running the query again without `LIMIT', because
     the result set need not be sent to the client.

     `SQL_CALC_FOUND_ROWS' and `FOUND_ROWS()' can be useful in
     situations when you want to restrict the number of rows that a
     query returns, but also determine the number of rows in the full
     result set without running the query again. An example is a Web
     script that presents a paged display containing links to the pages
     that show other sections of a search result. Using `FOUND_ROWS()'
     allows you to determine how many other pages are needed for the
     rest of the result.

     The use of `SQL_CALC_FOUND_ROWS' and `FOUND_ROWS()' is more complex
     for *Note `UNION': union. statements than for simple *Note
     `SELECT': select. statements, because `LIMIT' may occur at multiple
     places in a *Note `UNION': union. It may be applied to individual
     *Note `SELECT': select.  statements in the *Note `UNION': union, or
     global to the *Note `UNION': union. result as a whole.

     The intent of `SQL_CALC_FOUND_ROWS' for *Note `UNION': union. is
     that it should return the row count that would be returned without
     a global `LIMIT'. The conditions for use of `SQL_CALC_FOUND_ROWS'
     with *Note `UNION': union. are:

        * The `SQL_CALC_FOUND_ROWS' keyword must appear in the first
          *Note `SELECT': select. of the *Note `UNION': union.

        * The value of `FOUND_ROWS()' is exact only if *Note `UNION
          ALL': union. is used. If *Note `UNION': union. without `ALL'
          is used, duplicate removal occurs and the value of
          `FOUND_ROWS()' is only approximate.

        * If no `LIMIT' is present in the *Note `UNION': union,
          `SQL_CALC_FOUND_ROWS' is ignored and returns the number of
          rows in the temporary table that is created to process the
          *Note `UNION': union.

     Beyond the cases described here, the behavior of `FOUND_ROWS()' is
     undefined (for example, its value following a *Note `SELECT':
     select. statement that fails with an error).

     *Important*:

     `FOUND_ROWS()' is not replicated reliably using statement-based
     replication.  Starting with MySQL 6.0.4, this function is
     automatically replicated using row-based replication.

   *  `LAST_INSERT_ID()', `LAST_INSERT_ID(EXPR)'

     `LAST_INSERT_ID()' (no arguments) returns the _first_
     automatically generated value _successfully_ inserted for an
     `AUTO_INCREMENT' column as a result of the most recently executed
     *Note `INSERT': insert.  statement. The value of
     `LAST_INSERT_ID()' remains unchanged if no rows are successfully
     inserted.

     For example, after inserting a row that generates an
     `AUTO_INCREMENT' value, you can get the value like this:

          mysql> SELECT LAST_INSERT_ID();
                  -> 195

     The value of `LAST_INSERT_ID()' will be consistent across all
     versions if all rows in the *Note `INSERT': insert. or *Note
     `UPDATE': update. statement were successful.

     The currently executing statement does not affect the value of
     `LAST_INSERT_ID()'. Suppose that you generate an `AUTO_INCREMENT'
     value with one statement, and then refer to `LAST_INSERT_ID()' in a
     multiple-row *Note `INSERT': insert. statement that inserts rows
     into a table with its own `AUTO_INCREMENT' column. The value of
     `LAST_INSERT_ID()' will remain stable in the second statement; its
     value for the second and later rows is not affected by the earlier
     row insertions.  (However, if you mix references to
     `LAST_INSERT_ID()' and `LAST_INSERT_ID(EXPR)', the effect is
     undefined.)

     If the previous statement returned an error, the value of
     `LAST_INSERT_ID()' is undefined. For transactional tables, if the
     statement is rolled back due to an error, the value of
     `LAST_INSERT_ID()' is left undefined. For manual *Note `ROLLBACK':
     commit, the value of `LAST_INSERT_ID()' is not restored to that
     before the transaction; it remains as it was at the point of the
     *Note `ROLLBACK': commit.

     Within the body of a stored routine (procedure or function) or a
     trigger, the value of `LAST_INSERT_ID()' changes the same way as
     for statements executed outside the body of these kinds of
     objects. The effect of a stored routine or trigger upon the value
     of `LAST_INSERT_ID()' that is seen by following statements depends
     on the kind of routine:

        * If a stored procedure executes statements that change the
          value of `LAST_INSERT_ID()', the changed value will be seen
          by statements that follow the procedure call.

        * For stored functions and triggers that change the value, the
          value is restored when the function or trigger ends, so
          following statements will not see a changed value.

     The ID that was generated is maintained in the server on a
     _per-connection basis_. This means that the value returned by the
     function to a given client is the first `AUTO_INCREMENT' value
     generated for most recent statement affecting an `AUTO_INCREMENT'
     column _by that client_. This value cannot be affected by other
     clients, even if they generate `AUTO_INCREMENT' values of their
     own. This behavior ensures that each client can retrieve its own ID
     without concern for the activity of other clients, and without the
     need for locks or transactions.

     The value of `LAST_INSERT_ID()' is not changed if you set the
     `AUTO_INCREMENT' column of a row to a non-`magic' value (that is,
     a value that is not `NULL' and not `0').

     *Important*:

     If you insert multiple rows using a single *Note `INSERT': insert.
     statement, `LAST_INSERT_ID()' returns the value generated for the
     _first_ inserted row _only_. The reason for this is to make it
     possible to reproduce easily the same *Note `INSERT': insert.
     statement against some other server.

     For example:

          mysql> USE test;
          Database changed
          mysql> CREATE TABLE t (
              ->   id INT AUTO_INCREMENT NOT NULL PRIMARY KEY,
              ->   name VARCHAR(10) NOT NULL
              -> );
          Query OK, 0 rows affected (0.09 sec)

          mysql> INSERT INTO t VALUES (NULL, 'Bob');
          Query OK, 1 row affected (0.01 sec)

          mysql> SELECT * FROM t;
          +----+------+
          | id | name |
          +----+------+
          |  1 | Bob  |
          +----+------+
          1 row in set (0.01 sec)

          mysql> SELECT LAST_INSERT_ID();
          +------------------+
          | LAST_INSERT_ID() |
          +------------------+
          |                1 |
          +------------------+
          1 row in set (0.00 sec)

          mysql> INSERT INTO t VALUES
              -> (NULL, 'Mary'), (NULL, 'Jane'), (NULL, 'Lisa');
          Query OK, 3 rows affected (0.00 sec)
          Records: 3  Duplicates: 0  Warnings: 0

          mysql> SELECT * FROM t;
          +----+------+
          | id | name |
          +----+------+
          |  1 | Bob  |
          |  2 | Mary |
          |  3 | Jane |
          |  4 | Lisa |
          +----+------+
          4 rows in set (0.01 sec)

          mysql> SELECT LAST_INSERT_ID();
          +------------------+
          | LAST_INSERT_ID() |
          +------------------+
          |                2 |
          +------------------+
          1 row in set (0.00 sec)

     Although the second *Note `INSERT': insert.  statement inserted
     three new rows into `t', the ID generated for the first of these
     rows was `2', and it is this value that is returned by
     `LAST_INSERT_ID()' for the following *Note `SELECT': select.
     statement.

     If you use `INSERT IGNORE' and the row is ignored, the
     `AUTO_INCREMENT' counter is not incremented and `LAST_INSERT_ID()'
     returns `0', which reflects that no row was inserted.

     If EXPR is given as an argument to `LAST_INSERT_ID()', the value
     of the argument is returned by the function and is remembered as
     the next value to be returned by `LAST_INSERT_ID()'. This can be
     used to simulate sequences:

       1. Create a table to hold the sequence counter and initialize it:

               mysql> CREATE TABLE sequence (id INT NOT NULL);
               mysql> INSERT INTO sequence VALUES (0);

       2. Use the table to generate sequence numbers like this:

               mysql> UPDATE sequence SET id=LAST_INSERT_ID(id+1);
               mysql> SELECT LAST_INSERT_ID();

          The *Note `UPDATE': update. statement increments the sequence
          counter and causes the next call to `LAST_INSERT_ID()' to
          return the updated value. The *Note `SELECT': select.
          statement retrieves that value. The *Note
          `mysql_insert_id()': mysql-insert-id. C API function can also
          be used to get the value. See *Note mysql-insert-id::.

     You can generate sequences without calling `LAST_INSERT_ID()', but
     the utility of using the function this way is that the ID value is
     maintained in the server as the last automatically generated
     value. It is multi-user safe because multiple clients can issue
     the *Note `UPDATE': update.  statement and get their own sequence
     value with the *Note `SELECT': select. statement (or *Note
     `mysql_insert_id()': mysql-insert-id.), without affecting or being
     affected by other clients that generate their own sequence values.

     Note that *Note `mysql_insert_id()': mysql-insert-id.  is only
     updated after *Note `INSERT': insert.  and *Note `UPDATE': update.
     statements, so you cannot use the C API function to retrieve the
     value for `LAST_INSERT_ID(EXPR)' after executing other SQL
     statements like *Note `SELECT': select. or *Note `SET': set-option.

   *  `ROW_COUNT()'

     `ROW_COUNT()' returns the number of rows updated, inserted, or
     deleted by the preceding statement. This is the same as the row
     count that the *Note `mysql': mysql. client displays and the value
     from the *Note `mysql_affected_rows()': mysql-affected-rows. C API
     function.

          mysql> INSERT INTO t VALUES(1),(2),(3);
          Query OK, 3 rows affected (0.00 sec)
          Records: 3  Duplicates: 0  Warnings: 0

          mysql> SELECT ROW_COUNT();
          +-------------+
          | ROW_COUNT() |
          +-------------+
          |           3 |
          +-------------+
          1 row in set (0.00 sec)

          mysql> DELETE FROM t WHERE i IN(1,2);
          Query OK, 2 rows affected (0.00 sec)

          mysql> SELECT ROW_COUNT();
          +-------------+
          | ROW_COUNT() |
          +-------------+
          |           2 |
          +-------------+
          1 row in set (0.00 sec)

   *  `SCHEMA()'

     This function is a synonym for `DATABASE()'.

   *  `SESSION_USER()'

     `SESSION_USER()' is a synonym for `USER()'.

   *  `SYSTEM_USER()'

     `SYSTEM_USER()' is a synonym for `USER()'.

   *  `USER()'

     Returns the current MySQL user name and host name as a string in
     the `utf8' character set.

          mysql> SELECT USER();
                  -> 'davida@localhost'

     The value indicates the user name you specified when connecting to
     the server, and the client host from which you connected. The
     value can be different from that of `CURRENT_USER()'.

     You can extract only the user name part like this:

          mysql> SELECT SUBSTRING_INDEX(USER(),'@',1);
                  -> 'davida'

   *  `VERSION()'

     Returns a string that indicates the MySQL server version.  The
     string uses the `utf8' character set.

          mysql> SELECT VERSION();
                  -> '6.0.12-standard'

     Note that if your version string ends with `-log' this means that
     logging is enabled.


File: manual.info,  Node: miscellaneous-functions,  Prev: information-functions,  Up: other-functions

11.11.4 Miscellaneous Functions
-------------------------------

*Name*                        *Description*
`DEFAULT()'                   Return the default value for a table column
`GET_LOCK()'                  Get a named lock
`INET_ATON()'                 Return the numeric value of an IP address
`INET_NTOA()'                 Return the IP address from a numeric value
`IS_FREE_LOCK()'              Checks whether the named lock  is free
`IS_USED_LOCK()'(v4.1.0)      Checks whether the named lock is in use.
                              Return connection identifier if true.
`MASTER_POS_WAIT()'           Block until the slave has read and
                              applied all updates up to the specified
                              position
`NAME_CONST()'(v5.0.12)       Causes the column to have the given name
`RAND()'                      Return a random floating-point value
`RELEASE_LOCK()'              Releases the named lock
`SLEEP()'(v5.0.12)            Sleep for a number of seconds
`UUID_SHORT()'(v5.1.20)       Return an integer-valued universal
                              identifier
`UUID()'(v4.1.2)              Return a Universal Unique Identifier (UUID)
`VALUES()'(v4.1.1)            Defines the values to be used during an
                              INSERT

   *  `DEFAULT(COL_NAME)'

     Returns the default value for a table column. An error results if
     the column has no default value.

          mysql> UPDATE t SET i = DEFAULT(i)+1 WHERE id < 100;

   * `FORMAT(X,D)'

     Formats the number X to a format like `'#,###,###.##'', rounded to
     D decimal places, and returns the result as a string. For details,
     see *Note string-functions::.

   *  `GET_LOCK(STR,TIMEOUT)'

     Tries to obtain a lock with a name given by the string STR, using
     a timeout of TIMEOUT seconds. Returns `1' if the lock was obtained
     successfully, `0' if the attempt timed out (for example, because
     another client has previously locked the name), or `NULL' if an
     error occurred (such as running out of memory or the thread was
     killed with *Note `mysqladmin kill': mysqladmin.). If you have a
     lock obtained with `GET_LOCK()', it is released when you execute
     `RELEASE_LOCK()', execute a new `GET_LOCK()', or your connection
     terminates (either normally or abnormally). Locks obtained with
     `GET_LOCK()' do not interact with transactions. That is,
     committing a transaction does not release any such locks obtained
     during the transaction.

     This function can be used to implement application locks or to
     simulate record locks. Names are locked on a server-wide basis. If
     a name has been locked by one client, `GET_LOCK()' blocks any
     request by another client for a lock with the same name. This
     allows clients that agree on a given lock name to use the name to
     perform cooperative advisory locking. But be aware that it also
     allows a client that is not among the set of cooperating clients
     to lock a name, either inadvertently or deliberately, and thus
     prevent any of the cooperating clients from locking that name. One
     way to reduce the likelihood of this is to use lock names that are
     database-specific or application-specific. For example, use lock
     names of the form DB_NAME.STR or APP_NAME.STR.

          mysql> SELECT GET_LOCK('lock1',10);
                  -> 1
          mysql> SELECT IS_FREE_LOCK('lock2');
                  -> 1
          mysql> SELECT GET_LOCK('lock2',10);
                  -> 1
          mysql> SELECT RELEASE_LOCK('lock2');
                  -> 1
          mysql> SELECT RELEASE_LOCK('lock1');
                  -> NULL

     The second `RELEASE_LOCK()' call returns `NULL' because the lock
     `'lock1'' was automatically released by the second `GET_LOCK()'
     call.

     If multiple clients are waiting for a lock, the order in which
     they will acquire it is undefined and depends on factors such as
     the thread library in use. In particular, applications should not
     assume that clients will acquire the lock in the same order that
     they issued the lock requests.

     *Note*:

     Before MySQL 6.0.6, if a client attempts to acquire a lock that is
     already held by another client, it blocks according to the TIMEOUT
     argument. If the blocked client terminates, its thread does not
     die until the lock request times out.

   *  `INET_ATON(EXPR)'

     Given the dotted-quad representation of a network address as a
     string, returns an integer that represents the numeric value of
     the address. Addresses may be 4- or 8-byte addresses.

          mysql> SELECT INET_ATON('209.207.224.40');
                  -> 3520061480

     The generated number is always in network byte order. For the
     example just shown, the number is calculated as 209x256^3 +
     207x256^2 + 224x256 + 40.

     `INET_ATON()' also understands short-form IP addresses:

          mysql> SELECT INET_ATON('127.0.0.1'), INET_ATON('127.1');
                  -> 2130706433, 2130706433

     *Note*:

     When storing values generated by `INET_ATON()', it is recommended
     that you use an `INT UNSIGNED' column. If you use a (signed) *Note
     `INT': numeric-types. column, values corresponding to IP addresses
     for which the first octet is greater than 127 cannot be stored
     correctly. See *Note numeric-types::.

   *  `INET_NTOA(EXPR)'

     Given a numeric network address in network byte order (4 or 8
     byte), returns the dotted-quad representation of the address as a
     string.

          mysql> SELECT INET_NTOA(3520061480);
                  -> '209.207.224.40'

   *  `IS_FREE_LOCK(STR)'

     Checks whether the lock named STR is free to use (that is, not
     locked). Returns `1' if the lock is free (no one is using the
     lock), `0' if the lock is in use, and `NULL' if an error occurs
     (such as an incorrect argument).

   *  `IS_USED_LOCK(STR)'

     Checks whether the lock named STR is in use (that is, locked). If
     so, it returns the connection identifier of the client that holds
     the lock.  Otherwise, it returns `NULL'.

   *  `MASTER_POS_WAIT(LOG_NAME,LOG_POS[,TIMEOUT])'

     This function is useful for control of master/slave
     synchronization. It blocks until the slave has read and applied
     all updates up to the specified position in the master log. The
     return value is the number of log events the slave had to wait for
     to advance to the specified position.  The function returns `NULL'
     if the slave SQL thread is not started, the slave's master
     information is not initialized, the arguments are incorrect, or an
     error occurs. It returns `-1' if the timeout has been exceeded. If
     the slave SQL thread stops while `MASTER_POS_WAIT()' is waiting,
     the function returns `NULL'. If the slave is past the specified
     position, the function returns immediately.

     If a TIMEOUT value is specified, `MASTER_POS_WAIT()' stops waiting
     when TIMEOUT seconds have elapsed. TIMEOUT must be greater than 0;
     a zero or negative TIMEOUT means no timeout.

   *  `NAME_CONST(NAME,VALUE)'

     Returns the given value. When used to produce a result set column,
     `NAME_CONST()' causes the column to have the given name. The
     arguments should be constants.

          mysql> SELECT NAME_CONST('myname', 14);
          +--------+
          | myname |
          +--------+
          |     14 |
          +--------+

     This function was added in MySQL 5.0.12. It is for internal use
     only. The server uses it when writing statements from stored
     programs that contain references to local program variables, as
     described in *Note stored-programs-logging::, You might see this
     function in the output from *Note `mysqlbinlog': mysqlbinlog.

   *  `RELEASE_LOCK(STR)'

     Releases the lock named by the string STR that was obtained with
     `GET_LOCK()'. Returns `1' if the lock was released, `0' if the
     lock was not established by this thread (in which case the lock is
     not released), and `NULL' if the named lock did not exist. The
     lock does not exist if it was never obtained by a call to
     `GET_LOCK()' or if it has previously been released.

     The *Note `DO': do. statement is convenient to use with
     `RELEASE_LOCK()'. See *Note do::.

   *  `SLEEP(DURATION)'

     Sleeps (pauses) for the number of seconds given by the DURATION
     argument, then returns 0. If `SLEEP()' is interrupted, it returns
     1. The duration may have a fractional part given in microseconds.

   *  `UUID()'

     Returns a Universal Unique Identifier (UUID) generated according
     to `DCE 1.1: Remote Procedure Call' (Appendix A) CAE (Common
     Applications Environment) Specifications published by The Open
     Group in October 1997 (Document Number C706,
     `http://www.opengroup.org/public/pubs/catalog/c706.htm').

     A UUID is designed as a number that is globally unique in space
     and time. Two calls to `UUID()' are expected to generate two
     different values, even if these calls are performed on two
     separate computers that are not connected to each other.

     A UUID is a 128-bit number represented by a `utf8' string of five
     hexadecimal numbers in `aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee'
     format:

        * The first three numbers are generated from a timestamp.

        * The fourth number preserves temporal uniqueness in case the
          timestamp value loses monotonicity (for example, due to
          daylight saving time).

        * The fifth number is an IEEE 802 node number that provides
          spatial uniqueness. A random number is substituted if the
          latter is not available (for example, because the host
          computer has no Ethernet card, or we do not know how to find
          the hardware address of an interface on your operating
          system). In this case, spatial uniqueness cannot be
          guaranteed. Nevertheless, a collision should have _very_ low
          probability.

          Currently, the MAC address of an interface is taken into
          account only on FreeBSD and Linux. On other operating
          systems, MySQL uses a randomly generated 48-bit number.

          mysql> SELECT UUID();
                  -> '6ccd780c-baba-1026-9564-0040f4311e29'

     *Warning*:

     The `UUID()' function returns a string using the character set
     defined by the `character_set_server' parameter. If you are using
     UUID values in your tables and these columns are indexed the
     character set of your column or table should match the character
     set used when the `UUID()' was called. If you do not use the same
     character set for the column and the UUID value, then the indexes
     on those columns will not be used, which may lead to a reduction
     in performance and locked tables during operations as the table is
     searched sequentially for the value.

     You can convert between different character sets when using
     UUID-based strings using the `CONVERT()' function.

     *Note*:

     `UUID()' does not work with statement-based replication.

   *  `UUID_SHORT()'

     Returns a `short' universal identifier as a 64-bit unsigned
     integer (rather than a string-form 128-bit identifier as returned
     by the `UUID()' function).

     The value of `UUID_SHORT()' is guaranteed to be unique if the
     following conditions hold:

        * The `server_id' of the current host is unique among your set
          of master and slave servers

        * `server_id' is between 0 and 255

        * You don't set back your system time for your server between
          *Note `mysqld': mysqld. restarts

        * You do not invoke `UUID_SHORT()' on average more than 16
          million times per second between *Note `mysqld': mysqld.
          restarts

     The `UUID_SHORT()' return value is constructed this way:

            (server_id & 255) << 56
          + (server_startup_time_in_seconds << 24)
          + incremented_variable++;

          mysql> SELECT UUID_SHORT();
                  -> 92395783831158784

     Note that `UUID_SHORT()' does not work with statement-based
     replication.

   *  `VALUES(COL_NAME)'

     In an `INSERT ... ON DUPLICATE KEY UPDATE' statement, you can use
     the `VALUES(COL_NAME)' function in the *Note `UPDATE': update.
     clause to refer to column values from the *Note `INSERT': insert.
     portion of the statement. In other words, `VALUES(COL_NAME)' in
     the *Note `UPDATE': update. clause refers to the value of COL_NAME
     that would be inserted, had no duplicate-key conflict occurred.
     This function is especially useful in multiple-row inserts.  The
     `VALUES()' function is meaningful only in `INSERT ... ON DUPLICATE
     KEY UPDATE' statements and returns `NULL' otherwise.  *Note
     insert-on-duplicate::.

          mysql> INSERT INTO table (a,b,c) VALUES (1,2,3),(4,5,6)
              -> ON DUPLICATE KEY UPDATE c=VALUES(a)+VALUES(b);


File: manual.info,  Node: group-by-functions-and-modifiers,  Next: spatial-extensions,  Prev: other-functions,  Up: functions

11.12 Functions and Modifiers for Use with `GROUP BY' Clauses
=============================================================

* Menu:

* group-by-functions::           `GROUP BY' (Aggregate) Functions
* group-by-modifiers::           `GROUP BY' Modifiers
* group-by-hidden-columns::      `GROUP BY' and `HAVING' with Hidden Columns


File: manual.info,  Node: group-by-functions,  Next: group-by-modifiers,  Prev: group-by-functions-and-modifiers,  Up: group-by-functions-and-modifiers

11.12.1 `GROUP BY' (Aggregate) Functions
----------------------------------------

*Name*                        *Description*
`AVG()'                       Return the average value of the argument
`BIT_AND()'                   Return bitwise and
`BIT_OR()'                    Return bitwise or
`BIT_XOR()'(v4.1.1)           Return bitwise xor
`COUNT(DISTINCT)'             Return the count of a number of different
                              values
`COUNT()'                     Return a count of the number of rows
                              returned
`GROUP_CONCAT()'(v4.1)        Return a concatenated string
`MAX()'                       Return the maximum value
`MIN()'                       Return the minimum value
`STD()'                       Return the population standard deviation
`STDDEV_POP()'(v5.0.3)        Return the population standard deviation
`STDDEV_SAMP()'(v5.0.3)       Return the sample standard deviation
`STDDEV()'                    Return the population standard deviation
`SUM()'                       Return the sum
`VAR_POP()'(v5.0.3)           Return the population standard variance
`VAR_SAMP()'(v5.0.3)          Return the sample variance
`VARIANCE()'(v4.1)            Return the population standard variance

This section describes group (aggregate) functions that operate on sets
of values. Unless otherwise stated, group functions ignore `NULL'
values.

If you use a group function in a statement containing no `GROUP BY'
clause, it is equivalent to grouping on all rows.

For numeric arguments, the variance and standard deviation functions
return a *Note `DOUBLE': numeric-types. value.  The `SUM()' and `AVG()'
functions return a *Note `DECIMAL': numeric-types. value for exact-value
arguments (integer or *Note `DECIMAL': numeric-types.), and a *Note
`DOUBLE': numeric-types. value for approximate-value arguments (*Note
`FLOAT': numeric-types. or *Note `DOUBLE': numeric-types.).

The `SUM()' and `AVG()' aggregate functions do not work with temporal
values. (They convert the values to numbers, losing everything after
the first non-numeric character.) To work around this problem, you can
convert to numeric units, perform the aggregate operation, and convert
back to a temporal value. Examples:

     SELECT SEC_TO_TIME(SUM(TIME_TO_SEC(TIME_COL))) FROM TBL_NAME;
     SELECT FROM_DAYS(SUM(TO_DAYS(DATE_COL))) FROM TBL_NAME;

Functions such as `SUM()' or `AVG()' that expect a numeric argument
cast the argument to a number if necessary. For *Note `SET': set. or
*Note `ENUM': enum. values, the cast operation causes the underlying
numeric value to be used.

   *  `AVG([DISTINCT] EXPR)'

     Returns the average value of `EXPR'. The `DISTINCT' option can be
     used to return the average of the distinct values of EXPR.

     `AVG()' returns `NULL' if there were no matching rows.

          mysql> SELECT student_name, AVG(test_score)
              ->        FROM student
              ->        GROUP BY student_name;

   *  `BIT_AND(EXPR)'

     Returns the bitwise `AND' of all bits in EXPR. The calculation is
     performed with 64-bit (*Note `BIGINT': numeric-types.) precision.

     This function returns `18446744073709551615' if there were no
     matching rows. (This is the value of an unsigned *Note `BIGINT':
     numeric-types. value with all bits set to 1.)

   *  `BIT_OR(EXPR)'

     Returns the bitwise `OR' of all bits in EXPR. The calculation is
     performed with 64-bit (*Note `BIGINT': numeric-types.) precision.

     This function returns `0' if there were no matching rows.

   *  `BIT_XOR(EXPR)'

     Returns the bitwise `XOR' of all bits in EXPR. The calculation is
     performed with 64-bit (*Note `BIGINT': numeric-types.) precision.

     This function returns `0' if there were no matching rows.

   *  `COUNT(EXPR)'

     Returns a count of the number of non-`NULL' values of EXPR in the
     rows retrieved by a *Note `SELECT': select.  statement. The result
     is a *Note `BIGINT': numeric-types. value.

     `COUNT()' returns `0' if there were no matching rows.

          mysql> SELECT student.student_name,COUNT(*)
              ->        FROM student,course
              ->        WHERE student.student_id=course.student_id
              ->        GROUP BY student_name;

     `COUNT(*)' is somewhat different in that it returns a count of the
     number of rows retrieved, whether or not they contain `NULL'
     values.

     `COUNT(*)' is optimized to return very quickly if the *Note
     `SELECT': select. retrieves from one table, no other columns are
     retrieved, and there is no `WHERE' clause. For example:

          mysql> SELECT COUNT(*) FROM student;

     This optimization applies only to `MyISAM' tables only, because an
     exact row count is stored for this storage engine and can be
     accessed very quickly. For transactional storage engines such as
     `InnoDB', storing an exact row count is more problematic because
     multiple transactions may be occurring, each of which may affect
     the count.

   *  `COUNT(DISTINCT EXPR,[EXPR...])'

     Returns a count of the number of different non-`NULL' values.

     `COUNT(DISTINCT)' returns `0' if there were no matching rows.

          mysql> SELECT COUNT(DISTINCT results) FROM student;

     In MySQL, you can obtain the number of distinct expression
     combinations that do not contain `NULL' by giving a list of
     expressions. In standard SQL, you would have to do a concatenation
     of all expressions inside `COUNT(DISTINCT ...)'.

   *  `GROUP_CONCAT(EXPR)'

     This function returns a string result with the concatenated
     non-`NULL' values from a group. It returns `NULL' if there are no
     non-`NULL' values. The full syntax is as follows:

          GROUP_CONCAT([DISTINCT] EXPR [,EXPR ...]
                       [ORDER BY {UNSIGNED_INTEGER | COL_NAME | EXPR}
                           [ASC | DESC] [,COL_NAME ...]]
                       [SEPARATOR STR_VAL])

          mysql> SELECT student_name,
              ->     GROUP_CONCAT(test_score)
              ->     FROM student
              ->     GROUP BY student_name;

     Or:

          mysql> SELECT student_name,
              ->     GROUP_CONCAT(DISTINCT test_score
              ->               ORDER BY test_score DESC SEPARATOR ' ')
              ->     FROM student
              ->     GROUP BY student_name;

     In MySQL, you can get the concatenated values of expression
     combinations. You can eliminate duplicate values by using
     `DISTINCT'. If you want to sort values in the result, you should
     use `ORDER BY' clause. To sort in reverse order, add the `DESC'
     (descending) keyword to the name of the column you are sorting by
     in the `ORDER BY' clause. The default is ascending order; this may
     be specified explicitly using the `ASC' keyword. `SEPARATOR' is
     followed by the string value that should be inserted between
     values of result. The default is a comma (``,''). You can
     eliminate the separator altogether by specifying `SEPARATOR '''.

     The result is truncated to the maximum length that is given by the
     `group_concat_max_len' system variable, which has a default value
     of 1024. The value can be set higher, although the effective
     maximum length of the return value is constrained by the value of
     `max_allowed_packet'. The syntax to change the value of
     `group_concat_max_len' at runtime is as follows, where VAL is an
     unsigned integer:

          SET [GLOBAL | SESSION] group_concat_max_len = VAL;

     See also `CONCAT()' and `CONCAT_WS()': *Note string-functions::.

   *  `MAX([DISTINCT] EXPR)'

     Returns the maximum value of EXPR.  `MAX()' may take a string
     argument; in such cases, it returns the maximum string value. See
     *Note mysql-indexes::. The `DISTINCT' keyword can be used to find
     the maximum of the distinct values of EXPR, however, this produces
     the same result as omitting `DISTINCT'.

     `MAX()' returns `NULL' if there were no matching rows.

          mysql> SELECT student_name, MIN(test_score), MAX(test_score)
              ->        FROM student
              ->        GROUP BY student_name;

     For `MAX()', MySQL currently compares *Note `ENUM': enum. and
     *Note `SET': set. columns by their string value rather than by the
     string's relative position in the set. This differs from how
     `ORDER BY' compares them. This is expected to be rectified in a
     future MySQL release.

   *  `MIN([DISTINCT] EXPR)'

     Returns the minimum value of EXPR.  `MIN()' may take a string
     argument; in such cases, it returns the minimum string value. See
     *Note mysql-indexes::. The `DISTINCT' keyword can be used to find
     the minimum of the distinct values of EXPR, however, this produces
     the same result as omitting `DISTINCT'.

     `MIN()' returns `NULL' if there were no matching rows.

          mysql> SELECT student_name, MIN(test_score), MAX(test_score)
              ->        FROM student
              ->        GROUP BY student_name;

     For `MIN()', MySQL currently compares *Note `ENUM': enum. and
     *Note `SET': set. columns by their string value rather than by the
     string's relative position in the set. This differs from how
     `ORDER BY' compares them. This is expected to be rectified in a
     future MySQL release.

   *  `STD(EXPR)'

     Returns the population standard deviation of EXPR. This is an
     extension to standard SQL. The standard SQL function
     `STDDEV_POP()' can be used instead.

     This function returns `NULL' if there were no matching rows.

   *  `STDDEV(EXPR)'

     Returns the population standard deviation of EXPR. This function
     is provided for compatibility with Oracle. The standard SQL
     function `STDDEV_POP()' can be used instead.

     This function returns `NULL' if there were no matching rows.

   *  `STDDEV_POP(EXPR)'

     Returns the population standard deviation of EXPR (the square root
     of `VAR_POP()'). You can also use `STD()' or `STDDEV()', which are
     equivalent but not standard SQL.

     `STDDEV_POP()' returns `NULL' if there were no matching rows.

   *  `STDDEV_SAMP(EXPR)'

     Returns the sample standard deviation of EXPR (the square root of
     `VAR_SAMP()'.

     `STDDEV_SAMP()' returns `NULL' if there were no matching rows.

   *  `SUM([DISTINCT] EXPR)'

     Returns the sum of EXPR. If the return set has no rows, `SUM()'
     returns `NULL'. The `DISTINCT' keyword can be used in MySQL 6.0 to
     sum only the distinct values of EXPR.

     `SUM()' returns `NULL' if there were no matching rows.

   *  `VAR_POP(EXPR)'

     Returns the population standard variance of EXPR. It considers
     rows as the whole population, not as a sample, so it has the
     number of rows as the denominator. You can also use `VARIANCE()',
     which is equivalent but is not standard SQL.

     `VAR_POP()' returns `NULL' if there were no matching rows.

   *  `VAR_SAMP(EXPR)'

     Returns the sample variance of EXPR. That is, the denominator is
     the number of rows minus one.

     `VAR_SAMP()' returns `NULL' if there were no matching rows.

   *  `VARIANCE(EXPR)'

     Returns the population standard variance of EXPR. This is an
     extension to standard SQL. The standard SQL function `VAR_POP()'
     can be used instead.

     `VARIANCE()' returns `NULL' if there were no matching rows.


File: manual.info,  Node: group-by-modifiers,  Next: group-by-hidden-columns,  Prev: group-by-functions,  Up: group-by-functions-and-modifiers

11.12.2 `GROUP BY' Modifiers
----------------------------

The `GROUP BY' clause allows a `WITH ROLLUP' modifier that causes extra
rows to be added to the summary output. These rows represent
higher-level (or super-aggregate) summary operations. `ROLLUP' thus
allows you to answer questions at multiple levels of analysis with a
single query. It can be used, for example, to provide support for OLAP
(Online Analytical Processing) operations.

Suppose that a table named `sales' has `year', `country', `product',
and `profit' columns for recording sales profitability:

     CREATE TABLE sales
     (
         year    INT NOT NULL,
         country VARCHAR(20) NOT NULL,
         product VARCHAR(32) NOT NULL,
         profit  INT
     );

The table's contents can be summarized per year with a simple `GROUP
BY' like this:

     mysql> SELECT year, SUM(profit) FROM sales GROUP BY year;
     +------+-------------+
     | year | SUM(profit) |
     +------+-------------+
     | 2000 |        4525 |
     | 2001 |        3010 |
     +------+-------------+

This output shows the total profit for each year, but if you also want
to determine the total profit summed over all years, you must add up
the individual values yourself or run an additional query.

Or you can use `ROLLUP', which provides both levels of analysis with a
single query. Adding a `WITH ROLLUP' modifier to the `GROUP BY' clause
causes the query to produce another row that shows the grand total over
all year values:

     mysql> SELECT year, SUM(profit) FROM sales GROUP BY year WITH ROLLUP;
     +------+-------------+
     | year | SUM(profit) |
     +------+-------------+
     | 2000 |        4525 |
     | 2001 |        3010 |
     | NULL |        7535 |
     +------+-------------+

The grand total super-aggregate line is identified by the value `NULL'
in the `year' column.

`ROLLUP' has a more complex effect when there are multiple `GROUP BY'
columns. In this case, each time there is a `break' (change in value) in
any but the last grouping column, the query produces an extra
super-aggregate summary row.

For example, without `ROLLUP', a summary on the `sales' table based on
`year', `country', and `product' might look like this:

     mysql> SELECT year, country, product, SUM(profit)
         -> FROM sales
         -> GROUP BY year, country, product;
     +------+---------+------------+-------------+
     | year | country | product    | SUM(profit) |
     +------+---------+------------+-------------+
     | 2000 | Finland | Computer   |        1500 |
     | 2000 | Finland | Phone      |         100 |
     | 2000 | India   | Calculator |         150 |
     | 2000 | India   | Computer   |        1200 |
     | 2000 | USA     | Calculator |          75 |
     | 2000 | USA     | Computer   |        1500 |
     | 2001 | Finland | Phone      |          10 |
     | 2001 | USA     | Calculator |          50 |
     | 2001 | USA     | Computer   |        2700 |
     | 2001 | USA     | TV         |         250 |
     +------+---------+------------+-------------+

The output indicates summary values only at the year/country/product
level of analysis. When `ROLLUP' is added, the query produces several
extra rows:

     mysql> SELECT year, country, product, SUM(profit)
         -> FROM sales
         -> GROUP BY year, country, product WITH ROLLUP;
     +------+---------+------------+-------------+
     | year | country | product    | SUM(profit) |
     +------+---------+------------+-------------+
     | 2000 | Finland | Computer   |        1500 |
     | 2000 | Finland | Phone      |         100 |
     | 2000 | Finland | NULL       |        1600 |
     | 2000 | India   | Calculator |         150 |
     | 2000 | India   | Computer   |        1200 |
     | 2000 | India   | NULL       |        1350 |
     | 2000 | USA     | Calculator |          75 |
     | 2000 | USA     | Computer   |        1500 |
     | 2000 | USA     | NULL       |        1575 |
     | 2000 | NULL    | NULL       |        4525 |
     | 2001 | Finland | Phone      |          10 |
     | 2001 | Finland | NULL       |          10 |
     | 2001 | USA     | Calculator |          50 |
     | 2001 | USA     | Computer   |        2700 |
     | 2001 | USA     | TV         |         250 |
     | 2001 | USA     | NULL       |        3000 |
     | 2001 | NULL    | NULL       |        3010 |
     | NULL | NULL    | NULL       |        7535 |
     +------+---------+------------+-------------+

For this query, adding `ROLLUP' causes the output to include summary
information at four levels of analysis, not just one. Here is how to
interpret the `ROLLUP' output:

   * Following each set of product rows for a given year and country,
     an extra summary row is produced showing the total for all
     products. These rows have the `product' column set to `NULL'.

   * Following each set of rows for a given year, an extra summary row
     is produced showing the total for all countries and products.
     These rows have the `country' and `products' columns set to `NULL'.

   * Finally, following all other rows, an extra summary row is
     produced showing the grand total for all years, countries, and
     products. This row has the `year', `country', and `products'
     columns set to `NULL'.

*Other Considerations When using `ROLLUP'*

The following items list some behaviors specific to the MySQL
implementation of `ROLLUP':

When you use `ROLLUP', you cannot also use an `ORDER BY' clause to sort
the results. In other words, `ROLLUP' and `ORDER BY' are mutually
exclusive. However, you still have some control over sort order. `GROUP
BY' in MySQL sorts results, and you can use explicit `ASC' and `DESC'
keywords with columns named in the `GROUP BY' list to specify sort
order for individual columns. (The higher-level summary rows added by
`ROLLUP' still appear after the rows from which they are calculated,
regardless of the sort order.)

`LIMIT' can be used to restrict the number of rows returned to the
client. `LIMIT' is applied after `ROLLUP', so the limit applies against
the extra rows added by `ROLLUP'. For example:

     mysql> SELECT year, country, product, SUM(profit)
         -> FROM sales
         -> GROUP BY year, country, product WITH ROLLUP
         -> LIMIT 5;
     +------+---------+------------+-------------+
     | year | country | product    | SUM(profit) |
     +------+---------+------------+-------------+
     | 2000 | Finland | Computer   |        1500 |
     | 2000 | Finland | Phone      |         100 |
     | 2000 | Finland | NULL       |        1600 |
     | 2000 | India   | Calculator |         150 |
     | 2000 | India   | Computer   |        1200 |
     +------+---------+------------+-------------+

Using `LIMIT' with `ROLLUP' may produce results that are more difficult
to interpret, because you have less context for understanding the
super-aggregate rows.

The `NULL' indicators in each super-aggregate row are produced when the
row is sent to the client. The server looks at the columns named in the
`GROUP BY' clause following the leftmost one that has changed value. For
any column in the result set with a name that is a lexical match to any
of those names, its value is set to `NULL'. (If you specify grouping
columns by column number, the server identifies which columns to set to
`NULL' by number.)

Because the `NULL' values in the super-aggregate rows are placed into
the result set at such a late stage in query processing, you cannot
test them as `NULL' values within the query itself. For example, you
cannot add `HAVING product IS NULL' to the query to eliminate from the
output all but the super-aggregate rows.

On the other hand, the `NULL' values do appear as `NULL' on the client
side and can be tested as such using any MySQL client programming
interface.


File: manual.info,  Node: group-by-hidden-columns,  Prev: group-by-modifiers,  Up: group-by-functions-and-modifiers

11.12.3 `GROUP BY' and `HAVING' with Hidden Columns
---------------------------------------------------

MySQL extends the use of `GROUP BY' so that you can use non-aggregated
columns or calculations in the *Note `SELECT': select. list that do not
appear in the `GROUP BY' clause. You can use this feature to get better
performance by avoiding unnecessary column sorting and grouping. For
example, you do not need to group on `customer.name' in the following
query:

     SELECT order.custid, customer.name, MAX(payments)
       FROM order,customer
       WHERE order.custid = customer.custid
       GROUP BY order.custid;

In standard SQL, you would have to add `customer.name' to the `GROUP
BY' clause. In MySQL, the name is redundant.

Do _not_ use this feature if the columns you omit from the `GROUP BY'
part are not constant in the group. The server is free to return any
value from the group, so the results are indeterminate unless all
values are the same.

A similar MySQL extension applies to the `HAVING' clause. The SQL
standard does not allow the `HAVING' clause to name any column that is
not found in the `GROUP BY' clause if it is not enclosed in an
aggregate function. MySQL allows the use of such columns to simplify
calculations. This extension assumes that the non-grouped columns will
have the same group-wise values. Otherwise, the result is indeterminate.

If the `ONLY_FULL_GROUP_BY' SQL mode is enabled, the MySQL extension to
`GROUP BY' does not apply. That is, columns not named in the `GROUP BY'
clause cannot be used in the *Note `SELECT': select. list or `HAVING'
clause if not used in an aggregate function.

The select list extension also applies to `ORDER BY'. That is, you can
use non-aggregated columns or calculations in the `ORDER BY' clause
that do not appear in the `GROUP BY' clause. This extension does not
apply if the `ONLY_FULL_GROUP_BY' SQL mode is enabled.

In some cases, you can use `MIN()' and `MAX()' to obtain a specific
column value even if it isn't unique. The following gives the value of
`column' from the row containing the smallest value in the `sort'
column:

     SUBSTR(MIN(CONCAT(RPAD(sort,6,' '),column)),7)

See *Note example-maximum-column-group-row::.

Note that if you are trying to follow standard SQL, you can't use
expressions in `GROUP BY' clauses. You can work around this limitation
by using an alias for the expression:

     SELECT id,FLOOR(value/100) AS val
       FROM TBL_NAME
       GROUP BY id, val;

MySQL does allow expressions in `GROUP BY' clauses. For example:

     SELECT id,FLOOR(value/100)
       FROM TBL_NAME
       GROUP BY id, FLOOR(value/100);


File: manual.info,  Node: spatial-extensions,  Next: precision-math,  Prev: group-by-functions-and-modifiers,  Up: functions

11.13 Spatial Extensions
========================

* Menu:

* gis-introduction::             Introduction to MySQL Spatial Support
* opengis-geometry-model::       The OpenGIS Geometry Model
* supported-spatial-data-formats::  Supported Spatial Data Formats
* creating-a-spatially-enabled-mysql-database::  Creating a Spatially Enabled MySQL Database
* analysing-spatial-information::  Analyzing Spatial Information
* optimizing-spatial-analysis::  Optimizing Spatial Analysis
* mysql-gis-conformance-and-compatibility::  MySQL Conformance and Compatibility

MySQL supports spatial extensions to allow the generation, storage, and
analysis of geographic features. These features are available for
`MyISAM', `InnoDB', `NDB', and `ARCHIVE' tables.

For spatial columns, `MyISAM' supports both `SPATIAL' and non-`SPATIAL'
indexes. Other storage engines support non-`SPATIAL' indexes, as
described in *Note create-index::.

This chapter covers the following topics:

   * The basis of these spatial extensions in the OpenGIS geometry model

   * Data formats for representing spatial data

   * How to use spatial data in MySQL

   * Use of indexing for spatial data

   * MySQL differences from the OpenGIS specification

*Additional resources*

   * The Open Geospatial Consortium publishes the `OpenGIS(R) Simple
     Features Specifications For SQL', a document that proposes several
     conceptual ways for extending an SQL RDBMS to support spatial
     data. This specification is available from the OGC Web site at
     `http://www.opengis.org/docs/99-049.pdf'.

   * If you have questions or concerns about the use of the spatial
     extensions to MySQL, you can discuss them in the GIS forum:
     `http://forums.mysql.com/list.php?23'.


File: manual.info,  Node: gis-introduction,  Next: opengis-geometry-model,  Prev: spatial-extensions,  Up: spatial-extensions

11.13.1 Introduction to MySQL Spatial Support
---------------------------------------------

MySQL implements spatial extensions following the specification of the
Open Geospatial Consortium (OGC). This is an international consortium
of more than 250 companies, agencies, and universities participating in
the development of publicly available conceptual solutions that can be
useful with all kinds of applications that manage spatial data. The OGC
maintains a Web site at `http://www.opengis.org/'.

In 1997, the Open Geospatial Consortium published the `OpenGIS(R)
Simple Features Specifications For SQL', a document that proposes
several conceptual ways for extending an SQL RDBMS to support spatial
data. This specification is available from the OGC Web site at
`http://www.opengis.org/docs/99-049.pdf'. It contains additional
information relevant to this chapter.

MySQL implements a subset of the *SQL with Geometry Types* environment
proposed by OGC. This term refers to an SQL environment that has been
extended with a set of geometry types. A geometry-valued SQL column is
implemented as a column that has a geometry type. The specification
describe a set of SQL geometry types, as well as functions on those
types to create and analyze geometry values.

A *geographic feature* is anything in the world that has a location. A
feature can be:

   * An entity. For example, a mountain, a pond, a city.

   * A space. For example, town district, the tropics.

   * A definable location. For example, a crossroad, as a particular
     place where two streets intersect.

Some documents use the term *geospatial feature* to refer to geographic
features.

*Geometry* is another word that denotes a geographic feature.
Originally the word *geometry* meant measurement of the earth. Another
meaning comes from cartography, referring to the geometric features
that cartographers use to map the world.

This chapter uses all of these terms synonymously: *geographic feature*,
*geospatial feature*, *feature*, or *geometry*. Here, the term most
commonly used is *geometry*, defined as _a point or an aggregate of
points representing anything in the world that has a location_.


File: manual.info,  Node: opengis-geometry-model,  Next: supported-spatial-data-formats,  Prev: gis-introduction,  Up: spatial-extensions

11.13.2 The OpenGIS Geometry Model
----------------------------------

* Menu:

* gis-geometry-class-hierarchy::  The Geometry Class Hierarchy
* gis-class-geometry::           Class `Geometry'
* gis-class-point::              Class `Point'
* gis-class-curve::              Class `Curve'
* gis-class-linestring::         Class `LineString'
* gis-class-surface::            Class `Surface'
* gis-class-polygon::            Class `Polygon'
* gis-class-geometrycollection::  Class `GeometryCollection'
* gis-class-multipoint::         Class `MultiPoint'
* gis-class-multicurve::         Class `MultiCurve'
* gis-class-multilinestring::    Class `MultiLineString'
* gis-class-multisurface::       Class `MultiSurface'
* gis-class-multipolygon::       Class `MultiPolygon'

The set of geometry types proposed by OGC's *SQL with Geometry Types*
environment is based on the *OpenGIS Geometry Model*. In this model,
each geometric object has the following general properties:

   * It is associated with a Spatial Reference System, which describes
     the coordinate space in which the object is defined.

   * It belongs to some geometry class.


File: manual.info,  Node: gis-geometry-class-hierarchy,  Next: gis-class-geometry,  Prev: opengis-geometry-model,  Up: opengis-geometry-model

11.13.2.1 The Geometry Class Hierarchy
......................................

The geometry classes define a hierarchy as follows:

   * `Geometry' (non-instantiable)

        * `Point' (instantiable)

        * `Curve' (non-instantiable)

             * `LineString' (instantiable)

                  * `Line'

                  * `LinearRing'

        * `Surface' (non-instantiable)

             * `Polygon' (instantiable)

        * `GeometryCollection' (instantiable)

             * `MultiPoint' (instantiable)

             * `MultiCurve' (non-instantiable)

                  * `MultiLineString' (instantiable)

             * `MultiSurface' (non-instantiable)

                  * `MultiPolygon' (instantiable)

It is not possible to create objects in non-instantiable classes. It is
possible to create objects in instantiable classes. All classes have
properties, and instantiable classes may also have assertions (rules
that define valid class instances).

`Geometry' is the base class. It is an abstract class. The instantiable
subclasses of `Geometry' are restricted to zero-, one-, and
two-dimensional geometric objects that exist in two-dimensional
coordinate space. All instantiable geometry classes are defined so that
valid instances of a geometry class are topologically closed (that is,
all defined geometries include their boundary).

The base `Geometry' class has subclasses for `Point', `Curve',
`Surface', and `GeometryCollection':

   * `Point' represents zero-dimensional objects.

   * `Curve' represents one-dimensional objects, and has subclass
     `LineString', with sub-subclasses `Line' and `LinearRing'.

   * `Surface' is designed for two-dimensional objects and has subclass
     `Polygon'.

   * `GeometryCollection' has specialized zero-, one-, and
     two-dimensional collection classes named `MultiPoint',
     `MultiLineString', and `MultiPolygon' for modeling geometries
     corresponding to collections of `Points', `LineStrings', and
     `Polygons', respectively.  `MultiCurve' and `MultiSurface' are
     introduced as abstract superclasses that generalize the collection
     interfaces to handle `Curves' and `Surfaces'.

`Geometry', `Curve', `Surface', `MultiCurve', and `MultiSurface' are
defined as non-instantiable classes. They define a common set of
methods for their subclasses and are included for extensibility.

`Point', `LineString', `Polygon', `GeometryCollection', `MultiPoint',
`MultiLineString', and `MultiPolygon' are instantiable classes.


File: manual.info,  Node: gis-class-geometry,  Next: gis-class-point,  Prev: gis-geometry-class-hierarchy,  Up: opengis-geometry-model

11.13.2.2 Class `Geometry'
..........................

`Geometry' is the root class of the hierarchy.  It is a
non-instantiable class but has a number of properties that are common
to all geometry values created from any of the `Geometry' subclasses.
These properties are described in the following list. Particular
subclasses have their own specific properties, described later.

*Geometry Properties*

A geometry value has the following properties:

   * Its *type*. Each geometry belongs to one of the instantiable
     classes in the hierarchy.

   * Its *SRID*, or Spatial Reference Identifier. This value identifies
     the geometry's associated Spatial Reference System that describes
     the coordinate space in which the geometry object is defined.

     In MySQL, the SRID value is just an integer associated with the
     geometry value. All calculations are done assuming Euclidean
     (planar) geometry.

   * Its *coordinates* in its Spatial Reference System, represented as
     double-precision (eight-byte) numbers. All non-empty geometries
     include at least one pair of (X,Y) coordinates. Empty geometries
     contain no coordinates.

     Coordinates are related to the SRID. For example, in different
     coordinate systems, the distance between two objects may differ
     even when objects have the same coordinates, because the distance
     on the *planar* coordinate system and the distance on the
     *geocentric* system (coordinates on the Earth's surface) are
     different things.

   * Its *interior*, *boundary*, and *exterior*.

     Every geometry occupies some position in space. The exterior of a
     geometry is all space not occupied by the geometry. The interior
     is the space occupied by the geometry. The boundary is the
     interface between the geometry's interior and exterior.

   * Its *MBR* (Minimum Bounding Rectangle), or Envelope. This is the
     bounding geometry, formed by the minimum and maximum (X,Y)
     coordinates:

          ((MINX MINY, MAXX MINY, MAXX MAXY, MINX MAXY, MINX MINY))

   * Whether the value is *simple* or *non-simple*. Geometry values of
     types (`LineString', `MultiPoint', `MultiLineString') are either
     simple or non-simple. Each type determines its own assertions for
     being simple or non-simple.

   * Whether the value is *closed* or *not closed*. Geometry values of
     types (`LineString', `MultiString') are either closed or not
     closed. Each type determines its own assertions for being closed
     or not closed.

   * Whether the value is *empty* or *non-empty* A geometry is empty if
     it does not have any points. Exterior, interior, and boundary of
     an empty geometry are not defined (that is, they are represented
     by a `NULL' value). An empty geometry is defined to be always
     simple and has an area of 0.

   * Its *dimension*. A geometry can have a dimension of -1, 0, 1, or 2:

        * -1 for an empty geometry.

        * 0 for a geometry with no length and no area.

        * 1 for a geometry with non-zero length and zero area.

        * 2 for a geometry with non-zero area.

     `Point' objects have a dimension of zero.  `LineString' objects
     have a dimension of 1.  `Polygon' objects have a dimension of 2.
     The dimensions of `MultiPoint', `MultiLineString', and
     `MultiPolygon' objects are the same as the dimensions of the
     elements they consist of.


File: manual.info,  Node: gis-class-point,  Next: gis-class-curve,  Prev: gis-class-geometry,  Up: opengis-geometry-model

11.13.2.3 Class `Point'
.......................

A `Point' is a geometry that represents a single location in coordinate
space.

*`Point' Examples*

   * Imagine a large-scale map of the world with many cities. A `Point'
     object could represent each city.

   * On a city map, a `Point' object could represent a bus stop.

*`Point' Properties*

   * X-coordinate value.

   * Y-coordinate value.

   * `Point' is defined as a zero-dimensional geometry.

   * The boundary of a `Point' is the empty set.


File: manual.info,  Node: gis-class-curve,  Next: gis-class-linestring,  Prev: gis-class-point,  Up: opengis-geometry-model

11.13.2.4 Class `Curve'
.......................

A `Curve' is a one-dimensional geometry, usually represented by a
sequence of points. Particular subclasses of `Curve' define the type of
interpolation between points. `Curve' is a non-instantiable class.

*`Curve' Properties*

   * A `Curve' has the coordinates of its points.

   * A `Curve' is defined as a one-dimensional geometry.

   * A `Curve' is simple if it does not pass through the same point
     twice.

   * A `Curve' is closed if its start point is equal to its endpoint.

   * The boundary of a closed `Curve' is empty.

   * The boundary of a non-closed `Curve' consists of its two endpoints.

   * A `Curve' that is simple and closed is a `LinearRing'.


File: manual.info,  Node: gis-class-linestring,  Next: gis-class-surface,  Prev: gis-class-curve,  Up: opengis-geometry-model

11.13.2.5 Class `LineString'
............................

A `LineString' is a `Curve' with linear interpolation between points.

*`LineString' Examples*

   * On a world map, `LineString' objects could represent rivers.

   * In a city map, `LineString' objects could represent streets.

*`LineString' Properties*

   * A `LineString' has coordinates of segments, defined by each
     consecutive pair of points.

   * A `LineString' is a `Line' if it consists of exactly two points.

   * A `LineString' is a `LinearRing' if it is both closed and simple.


File: manual.info,  Node: gis-class-surface,  Next: gis-class-polygon,  Prev: gis-class-linestring,  Up: opengis-geometry-model

11.13.2.6 Class `Surface'
.........................

A `Surface' is a two-dimensional geometry. It is a non-instantiable
class. Its only instantiable subclass is `Polygon'.

*`Surface' Properties*

   * A `Surface' is defined as a two-dimensional geometry.

   * The OpenGIS specification defines a simple `Surface' as a geometry
     that consists of a single `patch' that is associated with a single
     exterior boundary and zero or more interior boundaries.

   * The boundary of a simple `Surface' is the set of closed curves
     corresponding to its exterior and interior boundaries.


File: manual.info,  Node: gis-class-polygon,  Next: gis-class-geometrycollection,  Prev: gis-class-surface,  Up: opengis-geometry-model

11.13.2.7 Class `Polygon'
.........................

A `Polygon' is a planar `Surface' representing a multisided geometry.
It is defined by a single exterior boundary and zero or more interior
boundaries, where each interior boundary defines a hole in the
`Polygon'.

*`Polygon' Examples*

   * On a region map, `Polygon' objects could represent forests,
     districts, and so on.

*`Polygon' Assertions*

   * The boundary of a `Polygon' consists of a set of `LinearRing'
     objects (that is, `LineString' objects that are both simple and
     closed) that make up its exterior and interior boundaries.

   * A `Polygon' has no rings that cross. The rings in the boundary of
     a `Polygon' may intersect at a `Point', but only as a tangent.

   * A `Polygon' has no lines, spikes, or punctures.

   * A `Polygon' has an interior that is a connected point set.

   * A `Polygon' may have holes. The exterior of a `Polygon' with holes
     is not connected.  Each hole defines a connected component of the
     exterior.

The preceding assertions make a `Polygon' a simple geometry.


File: manual.info,  Node: gis-class-geometrycollection,  Next: gis-class-multipoint,  Prev: gis-class-polygon,  Up: opengis-geometry-model

11.13.2.8 Class `GeometryCollection'
....................................

A `GeometryCollection' is a geometry that is a collection of one or
more geometries of any class.

All the elements in a `GeometryCollection' must be in the same Spatial
Reference System (that is, in the same coordinate system). There are no
other constraints on the elements of a `GeometryCollection', although
the subclasses of `GeometryCollection' described in the following
sections may restrict membership.  Restrictions may be based on:

   * Element type (for example, a `MultiPoint' may contain only `Point'
     elements)

   * Dimension

   * Constraints on the degree of spatial overlap between elements


File: manual.info,  Node: gis-class-multipoint,  Next: gis-class-multicurve,  Prev: gis-class-geometrycollection,  Up: opengis-geometry-model

11.13.2.9 Class `MultiPoint'
............................

A `MultiPoint' is a geometry collection composed of `Point' elements.
The points are not connected or ordered in any way.

*`MultiPoint' Examples*

   * On a world map, a `MultiPoint' could represent a chain of small
     islands.

   * On a city map, a `MultiPoint' could represent the outlets for a
     ticket office.

*`MultiPoint' Properties*

   * A `MultiPoint' is a zero-dimensional geometry.

   * A `MultiPoint' is simple if no two of its `Point' values are equal
     (have identical coordinate values).

   * The boundary of a `MultiPoint' is the empty set.


File: manual.info,  Node: gis-class-multicurve,  Next: gis-class-multilinestring,  Prev: gis-class-multipoint,  Up: opengis-geometry-model

11.13.2.10 Class `MultiCurve'
.............................

A `MultiCurve' is a geometry collection composed of `Curve' elements.
`MultiCurve' is a non-instantiable class.

*`MultiCurve' Properties*

   * A `MultiCurve' is a one-dimensional geometry.

   * A `MultiCurve' is simple if and only if all of its elements are
     simple; the only intersections between any two elements occur at
     points that are on the boundaries of both elements.

   * A `MultiCurve' boundary is obtained by applying the `mod 2 union
     rule' (also known as the `odd-even rule'): A point is in the
     boundary of a `MultiCurve' if it is in the boundaries of an odd
     number of `MultiCurve' elements.

   * A `MultiCurve' is closed if all of its elements are closed.

   * The boundary of a closed `MultiCurve' is always empty.


File: manual.info,  Node: gis-class-multilinestring,  Next: gis-class-multisurface,  Prev: gis-class-multicurve,  Up: opengis-geometry-model

11.13.2.11 Class `MultiLineString'
..................................

A `MultiLineString' is a `MultiCurve' geometry collection composed of
`LineString' elements.

*`MultiLineString' Examples*

   * On a region map, a `MultiLineString' could represent a river
     system or a highway system.


File: manual.info,  Node: gis-class-multisurface,  Next: gis-class-multipolygon,  Prev: gis-class-multilinestring,  Up: opengis-geometry-model

11.13.2.12 Class `MultiSurface'
...............................

A `MultiSurface' is a geometry collection composed of surface elements.
`MultiSurface' is a non-instantiable class. Its only instantiable
subclass is `MultiPolygon'.

*`MultiSurface' Assertions*

   * Two `MultiSurface' surfaces have no interiors that intersect.

   * Two `MultiSurface' elements have boundaries that intersect at most
     at a finite number of points.


File: manual.info,  Node: gis-class-multipolygon,  Prev: gis-class-multisurface,  Up: opengis-geometry-model

11.13.2.13 Class `MultiPolygon'
...............................

A `MultiPolygon' is a `MultiSurface' object composed of `Polygon'
elements.

*`MultiPolygon' Examples*

   * On a region map, a `MultiPolygon' could represent a system of
     lakes.

*`MultiPolygon' Assertions*

   * A `MultiPolygon' has no two `Polygon' elements with interiors that
     intersect.

   * A `MultiPolygon' has no two `Polygon' elements that cross
     (crossing is also forbidden by the previous assertion), or that
     touch at an infinite number of points.

   * A `MultiPolygon' may not have cut lines, spikes, or punctures. A
     `MultiPolygon' is a regular, closed point set.

   * A `MultiPolygon' that has more than one `Polygon' has an interior
     that is not connected. The number of connected components of the
     interior of a `MultiPolygon' is equal to the number of `Polygon'
     values in the `MultiPolygon'.

*`MultiPolygon' Properties*

   * A `MultiPolygon' is a two-dimensional geometry.

   * A `MultiPolygon' boundary is a set of closed curves (`LineString'
     values) corresponding to the boundaries of its `Polygon' elements.

   * Each `Curve' in the boundary of the `MultiPolygon' is in the
     boundary of exactly one `Polygon' element.

   * Every `Curve' in the boundary of an `Polygon' element is in the
     boundary of the `MultiPolygon'.


File: manual.info,  Node: supported-spatial-data-formats,  Next: creating-a-spatially-enabled-mysql-database,  Prev: opengis-geometry-model,  Up: spatial-extensions

11.13.3 Supported Spatial Data Formats
--------------------------------------

* Menu:

* gis-wkt-format::               Well-Known Text (WKT) Format
* gis-wkb-format::               Well-Known Binary (WKB) Format

This section describes the standard spatial data formats that are used
to represent geometry objects in queries. They are:

   * Well-Known Text (WKT) format

   * Well-Known Binary (WKB) format

Internally, MySQL stores geometry values in a format that is not
identical to either WKT or WKB format.


File: manual.info,  Node: gis-wkt-format,  Next: gis-wkb-format,  Prev: supported-spatial-data-formats,  Up: supported-spatial-data-formats

11.13.3.1 Well-Known Text (WKT) Format
......................................

The Well-Known Text (WKT) representation of Geometry is designed to
exchange geometry data in ASCII form.

Examples of WKT representations of geometry objects:

   * A `Point':

          POINT(15 20)

     Note that point coordinates are specified with no separating comma.

   * A `LineString' with four points:

          LINESTRING(0 0, 10 10, 20 25, 50 60)

     Note that point coordinate pairs are separated by commas.

   * A `Polygon' with one exterior ring and one interior ring:

          POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))

   * A `MultiPoint' with three `Point' values:

          MULTIPOINT(0 0, 20 20, 60 60)

   * A `MultiLineString' with two `LineString' values:

          MULTILINESTRING((10 10, 20 20), (15 15, 30 15))

   * A `MultiPolygon' with two `Polygon' values:

          MULTIPOLYGON(((0 0,10 0,10 10,0 10,0 0)),((5 5,7 5,7 7,5 7, 5 5)))

   * A `GeometryCollection' consisting of two `Point' values and one
     `LineString':

          GEOMETRYCOLLECTION(POINT(10 10), POINT(30 30), LINESTRING(15 15, 20 20))

A Backus-Naur grammar that specifies the formal production rules for
writing WKT values can be found in the OpenGIS specification document
referenced near the beginning of this chapter.


File: manual.info,  Node: gis-wkb-format,  Prev: gis-wkt-format,  Up: supported-spatial-data-formats

11.13.3.2 Well-Known Binary (WKB) Format
........................................

The Well-Known Binary (WKB) representation for geometric values is
defined by the OpenGIS specification. It is also defined in the ISO
`SQL/MM Part 3: Spatial' standard.

WKB is used to exchange geometry data as binary streams represented by
*Note `BLOB': blob. values containing geometric WKB information.

WKB uses one-byte unsigned integers, four-byte unsigned integers, and
eight-byte double-precision numbers (IEEE 754 format). A byte is eight
bits.

For example, a WKB value that corresponds to `POINT(1 1)' consists of
this sequence of 21 bytes (each represented here by two hex digits):

     0101000000000000000000F03F000000000000F03F

The sequence may be broken down into these components:

     Byte order : 01
     WKB type   : 01000000
     X          : 000000000000F03F
     Y          : 000000000000F03F

Component representation is as follows:

   * The byte order may be either 1 or 0 to indicate little-endian or
     big-endian storage. The little-endian and big-endian byte orders
     are also known as Network Data Representation (NDR) and External
     Data Representation (XDR), respectively.

   * The WKB type is a code that indicates the geometry type.  Values
     from 1 through 7 indicate `Point', `LineString', `Polygon',
     `MultiPoint', `MultiLineString', `MultiPolygon', and
     `GeometryCollection'.

   * A `Point' value has X and Y coordinates, each represented as a
     double-precision value.

WKB values for more complex geometry values are represented by more
complex data structures, as detailed in the OpenGIS specification.


File: manual.info,  Node: creating-a-spatially-enabled-mysql-database,  Next: analysing-spatial-information,  Prev: supported-spatial-data-formats,  Up: spatial-extensions

11.13.4 Creating a Spatially Enabled MySQL Database
---------------------------------------------------

* Menu:

* mysql-spatial-datatypes::      MySQL Spatial Data Types
* creating-spatial-values::      Creating Spatial Values
* creating-spatial-columns::     Creating Spatial Columns
* populating-spatial-columns::   Populating Spatial Columns
* fetching-spatial-data::        Fetching Spatial Data

This section describes the data types you can use for representing
spatial data in MySQL, and the functions available for creating and
retrieving spatial values.


File: manual.info,  Node: mysql-spatial-datatypes,  Next: creating-spatial-values,  Prev: creating-a-spatially-enabled-mysql-database,  Up: creating-a-spatially-enabled-mysql-database

11.13.4.1 MySQL Spatial Data Types
..................................

MySQL has data types that correspond to OpenGIS classes. Some of these
types hold single geometry values:

   * `GEOMETRY'

   * `POINT'

   * `LINESTRING'

   * `POLYGON'

`GEOMETRY' can store geometry values of any type. The other
single-value types (`POINT', `LINESTRING', and `POLYGON') restrict
their values to a particular geometry type.

The other data types hold collections of values:

   * `MULTIPOINT'

   * `MULTILINESTRING'

   * `MULTIPOLYGON'

   * `GEOMETRYCOLLECTION'

`GEOMETRYCOLLECTION' can store a collection of objects of any type. The
other collection types (`MULTIPOINT', `MULTILINESTRING',
`MULTIPOLYGON', and `GEOMETRYCOLLECTION') restrict collection members
to those having a particular geometry type.


File: manual.info,  Node: creating-spatial-values,  Next: creating-spatial-columns,  Prev: mysql-spatial-datatypes,  Up: creating-a-spatially-enabled-mysql-database

11.13.4.2 Creating Spatial Values
.................................

* Menu:

* gis-wkt-functions::            Creating Geometry Values Using WKT Functions
* gis-wkb-functions::            Creating Geometry Values Using WKB Functions
* gis-mysql-specific-functions::  Creating Geometry Values Using MySQL-Specific Functions

This section describes how to create spatial values using Well-Known
Text and Well-Known Binary functions that are defined in the OpenGIS
standard, and using MySQL-specific functions.


File: manual.info,  Node: gis-wkt-functions,  Next: gis-wkb-functions,  Prev: creating-spatial-values,  Up: creating-spatial-values

11.13.4.3 Creating Geometry Values Using WKT Functions
......................................................

MySQL provides a number of functions that take as input parameters a
Well-Known Text representation and, optionally, a spatial reference
system identifier (SRID). They return the corresponding geometry.

`GeomFromText()' accepts a WKT of any geometry type as its first
argument. An implementation also provides type-specific construction
functions for construction of geometry values of each geometry type.

   *  `GeomCollFromText(WKT[,SRID])',
     `GeometryCollectionFromText(WKT[,SRID])'

     Constructs a `GEOMETRYCOLLECTION' value using its WKT
     representation and SRID.

   *  `GeomFromText(WKT[,SRID])', `GeometryFromText(WKT[,SRID])'

     Constructs a geometry value of any type using its WKT
     representation and SRID.

   *  `LineFromText(WKT[,SRID])', `LineStringFromText(WKT[,SRID])'

     Constructs a `LINESTRING' value using its WKT representation and
     SRID.

   *  `MLineFromText(WKT[,SRID])', `MultiLineStringFromText(WKT[,SRID])'

     Constructs a `MULTILINESTRING' value using its WKT representation
     and SRID.

   *  `MPointFromText(WKT[,SRID])', `MultiPointFromText(WKT[,SRID])'

     Constructs a `MULTIPOINT' value using its WKT representation and
     SRID.

   *  `MPolyFromText(WKT[,SRID])', `MultiPolygonFromText(WKT[,SRID])'

     Constructs a `MULTIPOLYGON' value using its WKT representation and
     SRID.

   *  `PointFromText(WKT[,SRID])'

     Constructs a `POINT' value using its WKT representation and SRID.

   *  `PolyFromText(WKT[,SRID])', `PolygonFromText(WKT[,SRID])'

     Constructs a `POLYGON' value using its WKT representation and SRID.

The OpenGIS specification also defines the following optional
functions, which MySQL does not implement. These functions construct
`Polygon' or `MultiPolygon' values based on the WKT representation of a
collection of rings or closed `LineString' values. These values may
intersect.

   *  `BdMPolyFromText(WKT,SRID)'

     Constructs a `MultiPolygon' value from a `MultiLineString' value
     in WKT format containing an arbitrary collection of closed
     `LineString' values.

   *  `BdPolyFromText(WKT,SRID)'

     Constructs a `Polygon' value from a `MultiLineString' value in WKT
     format containing an arbitrary collection of closed `LineString'
     values.


File: manual.info,  Node: gis-wkb-functions,  Next: gis-mysql-specific-functions,  Prev: gis-wkt-functions,  Up: creating-spatial-values

11.13.4.4 Creating Geometry Values Using WKB Functions
......................................................

MySQL provides a number of functions that take as input parameters a
*Note `BLOB': blob. containing a Well-Known Binary representation and,
optionally, a spatial reference system identifier (SRID). They return
the corresponding geometry.

`GeomFromWKB()' accepts a WKB of any geometry type as its first
argument. An implementation also provides type-specific construction
functions for construction of geometry values of each geometry type.

   *  `GeomCollFromWKB(WKB[,SRID])',
     `GeometryCollectionFromWKB(WKB[,SRID])'

     Constructs a `GEOMETRYCOLLECTION' value using its WKB
     representation and SRID.

   *  `GeomFromWKB(WKB[,SRID])', `GeometryFromWKB(WKB[,SRID])'

     Constructs a geometry value of any type using its WKB
     representation and SRID.

   *  `LineFromWKB(WKB[,SRID])', `LineStringFromWKB(WKB[,SRID])'

     Constructs a `LINESTRING' value using its WKB representation and
     SRID.

   *  `MLineFromWKB(WKB[,SRID])', `MultiLineStringFromWKB(WKB[,SRID])'

     Constructs a `MULTILINESTRING' value using its WKB representation
     and SRID.

   *  `MPointFromWKB(WKB[,SRID])', `MultiPointFromWKB(WKB[,SRID])'

     Constructs a `MULTIPOINT' value using its WKB representation and
     SRID.

   *  `MPolyFromWKB(WKB[,SRID])', `MultiPolygonFromWKB(WKB[,SRID])'

     Constructs a `MULTIPOLYGON' value using its WKB representation and
     SRID.

   *  `PointFromWKB(WKB[,SRID])'

     Constructs a `POINT' value using its WKB representation and SRID.

   *  `PolyFromWKB(WKB[,SRID])', `PolygonFromWKB(WKB[,SRID])'

     Constructs a `POLYGON' value using its WKB representation and SRID.

The OpenGIS specification also describes optional functions for
constructing `Polygon' or `MultiPolygon' values based on the WKB
representation of a collection of rings or closed `LineString' values.
These values may intersect. MySQL does not implement these functions:

   *  `BdMPolyFromWKB(WKB,SRID)'

     Constructs a `MultiPolygon' value from a `MultiLineString' value
     in WKB format containing an arbitrary collection of closed
     `LineString' values.

   *  `BdPolyFromWKB(WKB,SRID)'

     Constructs a `Polygon' value from a `MultiLineString' value in WKB
     format containing an arbitrary collection of closed `LineString'
     values.


File: manual.info,  Node: gis-mysql-specific-functions,  Prev: gis-wkb-functions,  Up: creating-spatial-values

11.13.4.5 Creating Geometry Values Using MySQL-Specific Functions
.................................................................

MySQL provides a set of useful non-standard functions for creating
geometry WKB representations. The functions described in this section
are MySQL extensions to the OpenGIS specification. The results of these
functions are *Note `BLOB': blob. values containing WKB representations
of geometry values with no SRID. The results of these functions can be
substituted as the first argument for any function in the
`GeomFromWKB()' function family.

   *  `GeometryCollection(G1,G2,...)'

     Constructs a WKB `GeometryCollection'. If any argument is not a
     well-formed WKB representation of a geometry, the return value is
     `NULL'.

   *  `LineString(PT1,PT2,...)'

     Constructs a WKB `LineString' value from a number of WKB `Point'
     arguments. If any argument is not a WKB `Point', the return value
     is `NULL'. If the number of `Point' arguments is less than two, the
     return value is `NULL'.

   *  `MultiLineString(LS1,LS2,...)'

     Constructs a WKB `MultiLineString' value using WKB `LineString'
     arguments. If any argument is not a WKB `LineString', the return
     value is `NULL'.

   *  `MultiPoint(PT1,PT2,...)'

     Constructs a WKB `MultiPoint' value using WKB `Point' arguments.
     If any argument is not a WKB `Point', the return value is `NULL'.

   *  `MultiPolygon(POLY1,POLY2,...)'

     Constructs a WKB `MultiPolygon' value from a set of WKB `Polygon'
     arguments. If any argument is not a WKB `Polygon', the return
     value is `NULL'.

   *  `Point(X,Y)'

     Constructs a WKB `Point' using its coordinates.

   *  `Polygon(LS1,LS2,...)'

     Constructs a WKB `Polygon' value from a number of WKB `LineString'
     arguments. If any argument does not represent the WKB of a
     `LinearRing' (that is, not a closed and simple `LineString') the
     return value is `NULL'.


File: manual.info,  Node: creating-spatial-columns,  Next: populating-spatial-columns,  Prev: creating-spatial-values,  Up: creating-a-spatially-enabled-mysql-database

11.13.4.6 Creating Spatial Columns
..................................

MySQL provides a standard way of creating spatial columns for geometry
types, for example, with *Note `CREATE TABLE': create-table. or *Note
`ALTER TABLE': alter-table.  Currently, spatial columns are supported
for `MyISAM', `InnoDB', `NDB', and `ARCHIVE' tables. See also the
annotations about spatial indexes under *Note
creating-spatial-indexes::.

   * Use the *Note `CREATE TABLE': create-table.  statement to create a
     table with a spatial column:

          CREATE TABLE geom (g GEOMETRY);

   * Use the *Note `ALTER TABLE': alter-table. statement to add or drop
     a spatial column to or from an existing table:

          ALTER TABLE geom ADD pt POINT;
          ALTER TABLE geom DROP pt;


File: manual.info,  Node: populating-spatial-columns,  Next: fetching-spatial-data,  Prev: creating-spatial-columns,  Up: creating-a-spatially-enabled-mysql-database

11.13.4.7 Populating Spatial Columns
....................................

After you have created spatial columns, you can populate them with
spatial data.

Values should be stored in internal geometry format, but you can
convert them to that format from either Well-Known Text (WKT) or
Well-Known Binary (WKB) format. The following examples demonstrate how
to insert geometry values into a table by converting WKT values into
internal geometry format:

   * Perform the conversion directly in the *Note `INSERT': insert.
     statement:

          INSERT INTO geom VALUES (GeomFromText('POINT(1 1)'));

          SET @g = 'POINT(1 1)';
          INSERT INTO geom VALUES (GeomFromText(@g));

   * Perform the conversion prior to the *Note `INSERT': insert.:

          SET @g = GeomFromText('POINT(1 1)');
          INSERT INTO geom VALUES (@g);

The following examples insert more complex geometries into the table:

     SET @g = 'LINESTRING(0 0,1 1,2 2)';
     INSERT INTO geom VALUES (GeomFromText(@g));

     SET @g = 'POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))';
     INSERT INTO geom VALUES (GeomFromText(@g));

     SET @g =
     'GEOMETRYCOLLECTION(POINT(1 1),LINESTRING(0 0,1 1,2 2,3 3,4 4))';
     INSERT INTO geom VALUES (GeomFromText(@g));

The preceding examples all use `GeomFromText()' to create geometry
values. You can also use type-specific functions:

     SET @g = 'POINT(1 1)';
     INSERT INTO geom VALUES (PointFromText(@g));

     SET @g = 'LINESTRING(0 0,1 1,2 2)';
     INSERT INTO geom VALUES (LineStringFromText(@g));

     SET @g = 'POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))';
     INSERT INTO geom VALUES (PolygonFromText(@g));

     SET @g =
     'GEOMETRYCOLLECTION(POINT(1 1),LINESTRING(0 0,1 1,2 2,3 3,4 4))';
     INSERT INTO geom VALUES (GeomCollFromText(@g));

Note that if a client application program wants to use WKB
representations of geometry values, it is responsible for sending
correctly formed WKB in queries to the server. However, there are
several ways of satisfying this requirement. For example:

   * Inserting a `POINT(1 1)' value with hex literal syntax:

          mysql> INSERT INTO geom VALUES
              -> (GeomFromWKB(0x0101000000000000000000F03F000000000000F03F));

   * An ODBC application can send a WKB representation, binding it to a
     placeholder using an argument of *Note `BLOB': blob. type:

          INSERT INTO geom VALUES (GeomFromWKB(?))

     Other programming interfaces may support a similar placeholder
     mechanism.

   * In a C program, you can escape a binary value using *Note
     `mysql_real_escape_string()': mysql-real-escape-string.  and
     include the result in a query string that is sent to the server.
     See *Note mysql-real-escape-string::.


File: manual.info,  Node: fetching-spatial-data,  Prev: populating-spatial-columns,  Up: creating-a-spatially-enabled-mysql-database

11.13.4.8 Fetching Spatial Data
...............................

Geometry values stored in a table can be fetched in internal format.
You can also convert them into WKT or WKB format.

   * Fetching spatial data in internal format:

     Fetching geometry values using internal format can be useful in
     table-to-table transfers:

          CREATE TABLE geom2 (g GEOMETRY) SELECT g FROM geom;

   * Fetching spatial data in WKT format:

     The `AsText()' function converts a geometry from internal format
     into a WKT string.

          SELECT AsText(g) FROM geom;

   * Fetching spatial data in WKB format:

     The `AsBinary()' function converts a geometry from internal format
     into a *Note `BLOB': blob. containing the WKB value.

          SELECT AsBinary(g) FROM geom;


File: manual.info,  Node: analysing-spatial-information,  Next: optimizing-spatial-analysis,  Prev: creating-a-spatially-enabled-mysql-database,  Up: spatial-extensions

11.13.5 Analyzing Spatial Information
-------------------------------------

* Menu:

* functions-to-convert-geometries-between-formats::  Geometry Format Conversion Functions
* geometry-property-functions::  `Geometry' Functions
* functions-that-create-new-geometries-from-existing-ones::  Functions That Create New Geometries from Existing Ones
* functions-for-testing-spatial-relations-between-geometric-objects::  Functions for Testing Spatial Relations Between Geometric Objects
* relations-on-geometry-mbr::    Relations on Geometry Minimal Bounding Rectangles (MBRs)
* functions-that-test-spatial-relationships-between-geometries::  Functions That Test Spatial Relationships Between Geometries

After populating spatial columns with values, you are ready to query
and analyze them. MySQL provides a set of functions to perform various
operations on spatial data. These functions can be grouped into four
major categories according to the type of operation they perform:

   * Functions that convert geometries between various formats

   * Functions that provide access to qualitative or quantitative
     properties of a geometry

   * Functions that describe relations between two geometries

   * Functions that create new geometries from existing ones

Spatial analysis functions can be used in many contexts, such as:

   * Any interactive SQL program, such as *Note `mysql': mysql.  or
     MySQL Query Browser

   * Application programs written in any language that supports a MySQL
     client API


File: manual.info,  Node: functions-to-convert-geometries-between-formats,  Next: geometry-property-functions,  Prev: analysing-spatial-information,  Up: analysing-spatial-information

11.13.5.1 Geometry Format Conversion Functions
..............................................

MySQL supports the following functions for converting geometry values
between internal format and either WKT or WKB format:

   *  `AsBinary(G)', `AsWKB(G)'

     Converts a value in internal geometry format to its WKB
     representation and returns the binary result.

          SELECT AsBinary(g) FROM geom;

   *  `AsText(G)', `AsWKT(G)'

     Converts a value in internal geometry format to its WKT
     representation and returns the string result.

          mysql> SET @g = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT AsText(GeomFromText(@g));
          +--------------------------+
          | AsText(GeomFromText(@g)) |
          +--------------------------+
          | LINESTRING(1 1,2 2,3 3)  |
          +--------------------------+

   * `GeomFromText(WKT[,SRID])'

     Converts a string value from its WKT representation into internal
     geometry format and returns the result. A number of type-specific
     functions are also supported, such as `PointFromText()' and
     `LineFromText()'. See *Note gis-wkt-functions::.

   * `GeomFromWKB(WKB[,SRID])'

     Converts a binary value from its WKB representation into internal
     geometry format and returns the result. A number of type-specific
     functions are also supported, such as `PointFromWKB()' and
     `LineFromWKB()'. See *Note gis-wkb-functions::.


File: manual.info,  Node: geometry-property-functions,  Next: functions-that-create-new-geometries-from-existing-ones,  Prev: functions-to-convert-geometries-between-formats,  Up: analysing-spatial-information

11.13.5.2 `Geometry' Functions
..............................

* Menu:

* general-geometry-property-functions::  General Geometry Functions
* point-property-functions::     `Point' Functions
* linestring-property-functions::  `LineString' Functions
* multilinestring-property-functions::  `MultiLineString' Functions
* polygon-property-functions::   `Polygon' Functions
* multipolygon-property-functions::  `MultiPolygon' Functions
* geometrycollection-property-functions::  `GeometryCollection' Functions

Each function that belongs to this group takes a geometry value as its
argument and returns some quantitative or qualitative property of the
geometry. Some functions restrict their argument type. Such functions
return `NULL' if the argument is of an incorrect geometry type. For
example, `Area()' returns `NULL' if the object type is neither
`Polygon' nor `MultiPolygon'.


File: manual.info,  Node: general-geometry-property-functions,  Next: point-property-functions,  Prev: geometry-property-functions,  Up: geometry-property-functions

11.13.5.3 General Geometry Functions
....................................

The functions listed in this section do not restrict their argument and
accept a geometry value of any type.

   *  `Dimension(G)'

     Returns the inherent dimension of the geometry value G. The result
     can be -1, 0, 1, or 2. The meaning of these values is given in
     *Note gis-class-geometry::.

          mysql> SELECT Dimension(GeomFromText('LineString(1 1,2 2)'));
          +------------------------------------------------+
          | Dimension(GeomFromText('LineString(1 1,2 2)')) |
          +------------------------------------------------+
          |                                              1 |
          +------------------------------------------------+

   *  `Envelope(G)'

     Returns the Minimum Bounding Rectangle (MBR) for the geometry
     value G. The result is returned as a `Polygon' value.

     The polygon is defined by the corner points of the bounding box:

          POLYGON((MINX MINY, MAXX MINY, MAXX MAXY, MINX MAXY, MINX MINY))

          mysql> SELECT AsText(Envelope(GeomFromText('LineString(1 1,2 2)')));
          +-------------------------------------------------------+
          | AsText(Envelope(GeomFromText('LineString(1 1,2 2)'))) |
          +-------------------------------------------------------+
          | POLYGON((1 1,2 1,2 2,1 2,1 1))                        |
          +-------------------------------------------------------+

   *  `GeometryType(G)'

     Returns as a string the name of the geometry type of which the
     geometry instance G is a member. The name corresponds to one of
     the instantiable `Geometry' subclasses.

          mysql> SELECT GeometryType(GeomFromText('POINT(1 1)'));
          +------------------------------------------+
          | GeometryType(GeomFromText('POINT(1 1)')) |
          +------------------------------------------+
          | POINT                                    |
          +------------------------------------------+

   *  `SRID(G)'

     Returns an integer indicating the Spatial Reference System ID for
     the geometry value G.

     In MySQL, the SRID value is just an integer associated with the
     geometry value. All calculations are done assuming Euclidean
     (planar) geometry.

          mysql> SELECT SRID(GeomFromText('LineString(1 1,2 2)',101));
          +-----------------------------------------------+
          | SRID(GeomFromText('LineString(1 1,2 2)',101)) |
          +-----------------------------------------------+
          |                                           101 |
          +-----------------------------------------------+

The OpenGIS specification also defines the following functions, which
MySQL does not implement:

   *  `Boundary(G)'

     Returns a geometry that is the closure of the combinatorial
     boundary of the geometry value G.

   *  `IsEmpty(G)'

     Returns 1 if the geometry value G is the empty geometry, 0 if it
     is not empty, and -1 if the argument is `NULL'. If the geometry is
     empty, it represents the empty point set.

   *  `IsSimple(G)'

     Currently, this function is a placeholder and should not be used.
     If implemented, its behavior will be as described in the next
     paragraph.

     Returns 1 if the geometry value G has no anomalous geometric
     points, such as self-intersection or self-tangency.  `IsSimple()'
     returns 0 if the argument is not simple, and -1 if it is `NULL'.

     The description of each instantiable geometric class given earlier
     in the chapter includes the specific conditions that cause an
     instance of that class to be classified as not simple. (See *Note
     gis-geometry-class-hierarchy::.)


File: manual.info,  Node: point-property-functions,  Next: linestring-property-functions,  Prev: general-geometry-property-functions,  Up: geometry-property-functions

11.13.5.4 `Point' Functions
...........................

A `Point' consists of X and Y coordinates, which may be obtained using
the following functions:

   *  `X(P)'

     Returns the X-coordinate value for the point P as a
     double-precision number.

          mysql> SET @pt = 'Point(56.7 53.34)';
          mysql> SELECT X(GeomFromText(@pt));
          +----------------------+
          | X(GeomFromText(@pt)) |
          +----------------------+
          |                 56.7 |
          +----------------------+

   *  `Y(P)'

     Returns the Y-coordinate value for the point P as a
     double-precision number.

          mysql> SET @pt = 'Point(56.7 53.34)';
          mysql> SELECT Y(GeomFromText(@pt));
          +----------------------+
          | Y(GeomFromText(@pt)) |
          +----------------------+
          |                53.34 |
          +----------------------+


File: manual.info,  Node: linestring-property-functions,  Next: multilinestring-property-functions,  Prev: point-property-functions,  Up: geometry-property-functions

11.13.5.5 `LineString' Functions
................................

A `LineString' consists of `Point' values. You can extract particular
points of a `LineString', count the number of points that it contains,
or obtain its length.

   *  `EndPoint(LS)'

     Returns the `Point' that is the endpoint of the `LineString' value
     LS.

          mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT AsText(EndPoint(GeomFromText(@ls)));
          +-------------------------------------+
          | AsText(EndPoint(GeomFromText(@ls))) |
          +-------------------------------------+
          | POINT(3 3)                          |
          +-------------------------------------+

   *  `GLength(LS)'

     Returns as a double-precision number the length of the
     `LineString' value LS in its associated spatial reference.

          mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT GLength(GeomFromText(@ls));
          +----------------------------+
          | GLength(GeomFromText(@ls)) |
          +----------------------------+
          |            2.8284271247462 |
          +----------------------------+

     `GLength()' is a non-standard name. It corresponds to the OpenGIS
     `Length()' function.

   *  `NumPoints(LS)'

     Returns the number of `Point' objects in the `LineString' value LS.

          mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT NumPoints(GeomFromText(@ls));
          +------------------------------+
          | NumPoints(GeomFromText(@ls)) |
          +------------------------------+
          |                            3 |
          +------------------------------+

   *  `PointN(LS,N)'

     Returns the N-th `Point' in the `Linestring' value LS. Points are
     numbered beginning with 1.

          mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT AsText(PointN(GeomFromText(@ls),2));
          +-------------------------------------+
          | AsText(PointN(GeomFromText(@ls),2)) |
          +-------------------------------------+
          | POINT(2 2)                          |
          +-------------------------------------+

   *  `StartPoint(LS)'

     Returns the `Point' that is the start point of the `LineString'
     value LS.

          mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT AsText(StartPoint(GeomFromText(@ls)));
          +---------------------------------------+
          | AsText(StartPoint(GeomFromText(@ls))) |
          +---------------------------------------+
          | POINT(1 1)                            |
          +---------------------------------------+

The OpenGIS specification also defines the following function, which
MySQL does not implement:

   *  `IsRing(LS)'

     Returns 1 if the `LineString' value LS is closed (that is, its
     `StartPoint()' and `EndPoint()' values are the same) and is simple
     (does not pass through the same point more than once). Returns 0 if
     LS is not a ring, and -1 if it is `NULL'.


File: manual.info,  Node: multilinestring-property-functions,  Next: polygon-property-functions,  Prev: linestring-property-functions,  Up: geometry-property-functions

11.13.5.6 `MultiLineString' Functions
.....................................

These functions return properties of `MultiLineString' values.

   * `GLength(MLS)'

     Returns as a double-precision number the length of the
     `MultiLineString' value MLS. The length of MLS is equal to the sum
     of the lengths of its elements.

          mysql> SET @mls = 'MultiLineString((1 1,2 2,3 3),(4 4,5 5))';
          mysql> SELECT GLength(GeomFromText(@mls));
          +-----------------------------+
          | GLength(GeomFromText(@mls)) |
          +-----------------------------+
          |             4.2426406871193 |
          +-----------------------------+

     `GLength()' is a non-standard name. It corresponds to the OpenGIS
     `Length()' function.

   *  `IsClosed(MLS)'

     Returns 1 if the `MultiLineString' value MLS is closed (that is,
     the `StartPoint()' and `EndPoint()' values are the same for each
     `LineString' in MLS). Returns 0 if MLS is not closed, and -1 if it
     is `NULL'.

          mysql> SET @mls = 'MultiLineString((1 1,2 2,3 3),(4 4,5 5))';
          mysql> SELECT IsClosed(GeomFromText(@mls));
          +------------------------------+
          | IsClosed(GeomFromText(@mls)) |
          +------------------------------+
          |                            0 |
          +------------------------------+


File: manual.info,  Node: polygon-property-functions,  Next: multipolygon-property-functions,  Prev: multilinestring-property-functions,  Up: geometry-property-functions

11.13.5.7 `Polygon' Functions
.............................

These functions return properties of `Polygon' values.

   *  `Area(POLY)'

     Returns as a double-precision number the area of the `Polygon'
     value POLY, as measured in its spatial reference system.

          mysql> SET @poly = 'Polygon((0 0,0 3,3 0,0 0),(1 1,1 2,2 1,1 1))';
          mysql> SELECT Area(GeomFromText(@poly));
          +---------------------------+
          | Area(GeomFromText(@poly)) |
          +---------------------------+
          |                         4 |
          +---------------------------+

   *  `ExteriorRing(POLY)'

     Returns the exterior ring of the `Polygon' value POLY as a
     `LineString'.

          mysql> SET @poly =
              -> 'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))';
          mysql> SELECT AsText(ExteriorRing(GeomFromText(@poly)));
          +-------------------------------------------+
          | AsText(ExteriorRing(GeomFromText(@poly))) |
          +-------------------------------------------+
          | LINESTRING(0 0,0 3,3 3,3 0,0 0)           |
          +-------------------------------------------+

   *  `InteriorRingN(POLY,N)'

     Returns the N-th interior ring for the `Polygon' value POLY as a
     `LineString'. Rings are numbered beginning with 1.

          mysql> SET @poly =
              -> 'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))';
          mysql> SELECT AsText(InteriorRingN(GeomFromText(@poly),1));
          +----------------------------------------------+
          | AsText(InteriorRingN(GeomFromText(@poly),1)) |
          +----------------------------------------------+
          | LINESTRING(1 1,1 2,2 2,2 1,1 1)              |
          +----------------------------------------------+

   *  `NumInteriorRings(POLY)'

     Returns the number of interior rings in the `Polygon' value POLY.

          mysql> SET @poly =
              -> 'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))';
          mysql> SELECT NumInteriorRings(GeomFromText(@poly));
          +---------------------------------------+
          | NumInteriorRings(GeomFromText(@poly)) |
          +---------------------------------------+
          |                                     1 |
          +---------------------------------------+


File: manual.info,  Node: multipolygon-property-functions,  Next: geometrycollection-property-functions,  Prev: polygon-property-functions,  Up: geometry-property-functions

11.13.5.8 `MultiPolygon' Functions
..................................

These functions return properties of `MultiPolygon' values.

   * `Area(MPOLY)'

     Returns as a double-precision number the area of the
     `MultiPolygon' value MPOLY, as measured in its spatial reference
     system.

          mysql> SET @mpoly =
              -> 'MultiPolygon(((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1)))';
          mysql> SELECT Area(GeomFromText(@mpoly));
          +----------------------------+
          | Area(GeomFromText(@mpoly)) |
          +----------------------------+
          |                          8 |
          +----------------------------+

The OpenGIS specification also defines the following functions, which
MySQL does not implement:

   *  `Centroid(MPOLY)'

     Returns the mathematical centroid for the `MultiPolygon' value
     MPOLY as a `Point'. The result is not guaranteed to be on the
     `MultiPolygon'.

   * `PointOnSurface(MPOLY)'

     Returns a `Point' value that is guaranteed to be on the
     `MultiPolygon' value MPOLY.


File: manual.info,  Node: geometrycollection-property-functions,  Prev: multipolygon-property-functions,  Up: geometry-property-functions

11.13.5.9 `GeometryCollection' Functions
........................................

These functions return properties of `GeometryCollation' values.

   *  `GeometryN(GC,N)'

     Returns the N-th geometry in the `GeometryCollection' value GC.
     Geometries are numbered beginning with 1.

          mysql> SET @gc = 'GeometryCollection(Point(1 1),LineString(2 2, 3 3))';
          mysql> SELECT AsText(GeometryN(GeomFromText(@gc),1));
          +----------------------------------------+
          | AsText(GeometryN(GeomFromText(@gc),1)) |
          +----------------------------------------+
          | POINT(1 1)                             |
          +----------------------------------------+

   *  `NumGeometries(GC)'

     Returns the number of geometries in the `GeometryCollection' value
     GC.

          mysql> SET @gc = 'GeometryCollection(Point(1 1),LineString(2 2, 3 3))';
          mysql> SELECT NumGeometries(GeomFromText(@gc));
          +----------------------------------+
          | NumGeometries(GeomFromText(@gc)) |
          +----------------------------------+
          |                                2 |
          +----------------------------------+


File: manual.info,  Node: functions-that-create-new-geometries-from-existing-ones,  Next: functions-for-testing-spatial-relations-between-geometric-objects,  Prev: geometry-property-functions,  Up: analysing-spatial-information

11.13.5.10 Functions That Create New Geometries from Existing Ones
..................................................................

* Menu:

* functions-that-produce-new-geometries::  Geometry Functions That Produce New Geometries
* spatial-operators::            Spatial Operators

The following sections describe functions that take geometry values as
arguments and return new geometry values.


File: manual.info,  Node: functions-that-produce-new-geometries,  Next: spatial-operators,  Prev: functions-that-create-new-geometries-from-existing-ones,  Up: functions-that-create-new-geometries-from-existing-ones

11.13.5.11 Geometry Functions That Produce New Geometries
.........................................................

*Note geometry-property-functions::, discusses several functions that
construct new geometries from existing ones. See that section for
descriptions of these functions:

   * `Envelope(G)'

   * `StartPoint(LS)'

   * `EndPoint(LS)'

   * `PointN(LS,N)'

   * `ExteriorRing(POLY)'

   * `InteriorRingN(POLY,N)'

   * `GeometryN(GC,N)'


File: manual.info,  Node: spatial-operators,  Prev: functions-that-produce-new-geometries,  Up: functions-that-create-new-geometries-from-existing-ones

11.13.5.12 Spatial Operators
............................

OpenGIS proposes a number of other functions that can produce
geometries. They are designed to implement spatial operators.

These functions are not implemented in MySQL. They may appear in future
releases.

   *  `Buffer(G,D)'

     Returns a geometry that represents all points whose distance from
     the geometry value G is less than or equal to a distance of D.

   *  `ConvexHull(G)'

     Returns a geometry that represents the convex hull of the geometry
     value G.

   *  `Difference(G1,G2)'

     Returns a geometry that represents the point set difference of the
     geometry value G1 with G2.

   *  `Intersection(G1,G2)'

     Returns a geometry that represents the point set intersection of
     the geometry values G1 with G2.

   *  `SymDifference(G1,G2)'

     Returns a geometry that represents the point set symmetric
     difference of the geometry value G1 with G2.

   *  `Union(G1,G2)'

     Returns a geometry that represents the point set union of the
     geometry values G1 and G2.


File: manual.info,  Node: functions-for-testing-spatial-relations-between-geometric-objects,  Next: relations-on-geometry-mbr,  Prev: functions-that-create-new-geometries-from-existing-ones,  Up: analysing-spatial-information

11.13.5.13 Functions for Testing Spatial Relations Between Geometric Objects
............................................................................

The functions described in these sections take two geometries as input
parameters and return a qualitative or quantitative relation between
them.


File: manual.info,  Node: relations-on-geometry-mbr,  Next: functions-that-test-spatial-relationships-between-geometries,  Prev: functions-for-testing-spatial-relations-between-geometric-objects,  Up: analysing-spatial-information

11.13.5.14 Relations on Geometry Minimal Bounding Rectangles (MBRs)
...................................................................

MySQL provides several functions that test relations between minimal
bounding rectangles of two geometries `g1' and `g2'. The return values
1 and 0 indicate true and false, respectively.

   *  `MBRContains(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangle
     of G1 contains the Minimum Bounding Rectangle of G2.  This tests
     the opposite relationship as `MBRWithin()'.

          mysql> SET @g1 = GeomFromText('Polygon((0 0,0 3,3 3,3 0,0 0))');
          mysql> SET @g2 = GeomFromText('Point(1 1)');
          mysql> SELECT MBRContains(@g1,@g2), MBRContains(@g2,@g1);
          ----------------------+----------------------+
          | MBRContains(@g1,@g2) | MBRContains(@g2,@g1) |
          +----------------------+----------------------+
          |                    1 |                    0 |
          +----------------------+----------------------+

   *  `MBRDisjoint(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangles
     of the two geometries G1 and G2 are disjoint (do not intersect).

   *  `MBREqual(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangles
     of the two geometries G1 and G2 are the same.

   *  `MBRIntersects(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangles
     of the two geometries G1 and G2 intersect.

   *  `MBROverlaps(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangles
     of the two geometries G1 and G2 overlap. The term _spatially
     overlaps_ is used if two geometries intersect and their
     intersection results in a geometry of the same dimension but not
     equal to either of the given geometries.

   *  `MBRTouches(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangles
     of the two geometries G1 and G2 touch. Two geometries _spatially
     touch_ if the interiors of the geometries do not intersect, but
     the boundary of one of the geometries intersects either the
     boundary or the interior of the other.

   *  `MBRWithin(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangle
     of G1 is within the Minimum Bounding Rectangle of G2.  This tests
     the opposite relationship as `MBRContains()'.

          mysql> SET @g1 = GeomFromText('Polygon((0 0,0 3,3 3,3 0,0 0))');
          mysql> SET @g2 = GeomFromText('Polygon((0 0,0 5,5 5,5 0,0 0))');
          mysql> SELECT MBRWithin(@g1,@g2), MBRWithin(@g2,@g1);
          +--------------------+--------------------+
          | MBRWithin(@g1,@g2) | MBRWithin(@g2,@g1) |
          +--------------------+--------------------+
          |                  1 |                  0 |
          +--------------------+--------------------+


File: manual.info,  Node: functions-that-test-spatial-relationships-between-geometries,  Prev: relations-on-geometry-mbr,  Up: analysing-spatial-information

11.13.5.15 Functions That Test Spatial Relationships Between Geometries
.......................................................................

The OpenGIS specification defines the following functions. They test
the relationship between two geometry values `g1' and `g2'.

The return values 1 and 0 indicate true and false, respectively.

*Note*:

Currently, MySQL does not implement these functions according to the
specification. Those that are implemented return the same result as the
corresponding MBR-based functions. This includes functions in the
following list other than `Distance()' and `Related()'.

These functions may be implemented in future releases with full support
for spatial analysis, not just MBR-based support.

   *  `Contains(G1,G2)'

     Returns 1 or 0 to indicate whether G1 completely contains G2. This
     tests the opposite relationship as `Within()'.

   *  `Crosses(G1,G2)'

     Returns 1 if G1 spatially crosses G2. Returns `NULL' if `g1' is a
     `Polygon' or a `MultiPolygon', or if G2 is a `Point' or a
     `MultiPoint'. Otherwise, returns 0.

     The term _spatially crosses_ denotes a spatial relation between
     two given geometries that has the following properties:

        * The two geometries intersect

        * Their intersection results in a geometry that has a dimension
          that is one less than the maximum dimension of the two given
          geometries

        * Their intersection is not equal to either of the two given
          geometries

   *  `Disjoint(G1,G2)'

     Returns 1 or 0 to indicate whether G1 is spatially disjoint from
     (does not intersect) G2.

   *  `Distance(G1,G2)'

     Returns as a double-precision number the shortest distance between
     any two points in the two geometries.

   *  `Equals(G1,G2)'

     Returns 1 or 0 to indicate whether G1 is spatially equal to G2.

   *  `Intersects(G1,G2)'

     Returns 1 or 0 to indicate whether G1 spatially intersects G2.

   *  `Overlaps(G1,G2)'

     Returns 1 or 0 to indicate whether G1 spatially overlaps G2. The
     term _spatially overlaps_ is used if two geometries intersect and
     their intersection results in a geometry of the same dimension but
     not equal to either of the given geometries.

   *  `Related(G1,G2,PATTERN_MATRIX)'

     Returns 1 or 0 to indicate whether the spatial relationship
     specified by PATTERN_MATRIX exists between G1 and G2. Returns -1
     if the arguments are `NULL'. The pattern matrix is a string. Its
     specification will be noted here if this function is implemented.

   *  `Touches(G1,G2)'

     Returns 1 or 0 to indicate whether G1 spatially touches G2. Two
     geometries _spatially touch_ if the interiors of the geometries do
     not intersect, but the boundary of one of the geometries
     intersects either the boundary or the interior of the other.

   *  `Within(G1,G2)'

     Returns 1 or 0 to indicate whether G1 is spatially within G2. This
     tests the opposite relationship as `Contains()'.


File: manual.info,  Node: optimizing-spatial-analysis,  Next: mysql-gis-conformance-and-compatibility,  Prev: analysing-spatial-information,  Up: spatial-extensions

11.13.6 Optimizing Spatial Analysis
-----------------------------------

* Menu:

* creating-spatial-indexes::     Creating Spatial Indexes
* using-a-spatial-index::        Using a Spatial Index

Search operations in non-spatial databases can be optimized using
`SPATIAL' indexes. This is true for spatial databases as well. With the
help of a great variety of multi-dimensional indexing methods that have
previously been designed, it is possible to optimize spatial searches.
The most typical of these are:

   * Point queries that search for all objects that contain a given
     point

   * Region queries that search for all objects that overlap a given
     region

MySQL uses *R-Trees with quadratic splitting* for `SPATIAL' indexes on
spatial columns. A `SPATIAL' index is built using the MBR of a
geometry. For most geometries, the MBR is a minimum rectangle that
surrounds the geometries. For a horizontal or a vertical linestring,
the MBR is a rectangle degenerated into the linestring. For a point,
the MBR is a rectangle degenerated into the point.

It is also possible to create normal indexes on spatial columns.  In a
non-`SPATIAL' index, you must declare a prefix for any spatial column
except for `POINT' columns.

`MyISAM' supports both `SPATIAL' and non-`SPATIAL' indexes. Other
storage engines support non-`SPATIAL' indexes, as described in *Note
create-index::.


File: manual.info,  Node: creating-spatial-indexes,  Next: using-a-spatial-index,  Prev: optimizing-spatial-analysis,  Up: optimizing-spatial-analysis

11.13.6.1 Creating Spatial Indexes
..................................

MySQL can create spatial indexes using syntax similar to that for
creating regular indexes, but extended with the `SPATIAL' keyword.
Currently, columns in spatial indexes must be declared `NOT NULL'.  The
following examples demonstrate how to create spatial indexes:

   * With *Note `CREATE TABLE': create-table.:

          CREATE TABLE geom (g GEOMETRY NOT NULL, SPATIAL INDEX(g));

   * With *Note `ALTER TABLE': alter-table.:

          ALTER TABLE geom ADD SPATIAL INDEX(g);

   * With *Note `CREATE INDEX': create-index.:

          CREATE SPATIAL INDEX sp_index ON geom (g);

For `MyISAM' tables, `SPATIAL INDEX' creates an R-tree index. For
storage engines that support non-spatial indexing of spatial columns,
the engine creates a B-tree index. A B-tree index on spatial values
will be useful for exact-value lookups, but not for range scans.

For more information on indexing spatial columns, see *Note
create-index::.

To drop spatial indexes, use *Note `ALTER TABLE': alter-table. or *Note
`DROP INDEX': drop-index.:

   * With *Note `ALTER TABLE': alter-table.:

          ALTER TABLE geom DROP INDEX g;

   * With *Note `DROP INDEX': drop-index.:

          DROP INDEX sp_index ON geom;

Example: Suppose that a table `geom' contains more than 32,000
geometries, which are stored in the column `g' of type `GEOMETRY'. The
table also has an `AUTO_INCREMENT' column `fid' for storing object ID
values.

     mysql> DESCRIBE geom;
     +-------+----------+------+-----+---------+----------------+
     | Field | Type     | Null | Key | Default | Extra          |
     +-------+----------+------+-----+---------+----------------+
     | fid   | int(11)  |      | PRI | NULL    | auto_increment |
     | g     | geometry |      |     |         |                |
     +-------+----------+------+-----+---------+----------------+
     2 rows in set (0.00 sec)

     mysql> SELECT COUNT(*) FROM geom;
     +----------+
     | count(*) |
     +----------+
     |    32376 |
     +----------+
     1 row in set (0.00 sec)

To add a spatial index on the column `g', use this statement:

     mysql> ALTER TABLE geom ADD SPATIAL INDEX(g);
     Query OK, 32376 rows affected (4.05 sec)
     Records: 32376  Duplicates: 0  Warnings: 0


File: manual.info,  Node: using-a-spatial-index,  Prev: creating-spatial-indexes,  Up: optimizing-spatial-analysis

11.13.6.2 Using a Spatial Index
...............................

The optimizer investigates whether available spatial indexes can be
involved in the search for queries that use a function such as
`MBRContains()' or `MBRWithin()' in the `WHERE' clause. The following
query finds all objects that are in the given rectangle:

     mysql> SET @poly =
         -> 'Polygon((30000 15000,
                                    31000 15000,
                                    31000 16000,
                                    30000 16000,
                                    30000 15000))';
     mysql> SELECT fid,AsText(g) FROM geom WHERE
         -> MBRContains(GeomFromText(@poly),g);
     +-----+---------------------------------------------------------------+
     | fid | AsText(g)                                                     |
     +-----+---------------------------------------------------------------+
     |  21 | LINESTRING(30350.4 15828.8,30350.6 15845,30333.8 15845,30 ... |
     |  22 | LINESTRING(30350.6 15871.4,30350.6 15887.8,30334 15887.8, ... |
     |  23 | LINESTRING(30350.6 15914.2,30350.6 15930.4,30334 15930.4, ... |
     |  24 | LINESTRING(30290.2 15823,30290.2 15839.4,30273.4 15839.4, ... |
     |  25 | LINESTRING(30291.4 15866.2,30291.6 15882.4,30274.8 15882. ... |
     |  26 | LINESTRING(30291.6 15918.2,30291.6 15934.4,30275 15934.4, ... |
     | 249 | LINESTRING(30337.8 15938.6,30337.8 15946.8,30320.4 15946. ... |
     |   1 | LINESTRING(30250.4 15129.2,30248.8 15138.4,30238.2 15136. ... |
     |   2 | LINESTRING(30220.2 15122.8,30217.2 15137.8,30207.6 15136, ... |
     |   3 | LINESTRING(30179 15114.4,30176.6 15129.4,30167 15128,3016 ... |
     |   4 | LINESTRING(30155.2 15121.4,30140.4 15118.6,30142 15109,30 ... |
     |   5 | LINESTRING(30192.4 15085,30177.6 15082.2,30179.2 15072.4, ... |
     |   6 | LINESTRING(30244 15087,30229 15086.2,30229.4 15076.4,3024 ... |
     |   7 | LINESTRING(30200.6 15059.4,30185.6 15058.6,30186 15048.8, ... |
     |  10 | LINESTRING(30179.6 15017.8,30181 15002.8,30190.8 15003.6, ... |
     |  11 | LINESTRING(30154.2 15000.4,30168.6 15004.8,30166 15014.2, ... |
     |  13 | LINESTRING(30105 15065.8,30108.4 15050.8,30118 15053,3011 ... |
     | 154 | LINESTRING(30276.2 15143.8,30261.4 15141,30263 15131.4,30 ... |
     | 155 | LINESTRING(30269.8 15084,30269.4 15093.4,30258.6 15093,30 ... |
     | 157 | LINESTRING(30128.2 15011,30113.2 15010.2,30113.6 15000.4, ... |
     +-----+---------------------------------------------------------------+
     20 rows in set (0.00 sec)

Use *Note `EXPLAIN': explain. to check the way this query is executed:

     mysql> SET @poly =
         -> 'Polygon((30000 15000,
                                    31000 15000,
                                    31000 16000,
                                    30000 16000,
                                    30000 15000))';
     mysql> EXPLAIN SELECT fid,AsText(g) FROM geom WHERE
         -> MBRContains(GeomFromText(@poly),g)\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: geom
              type: range
     possible_keys: g
               key: g
           key_len: 32
               ref: NULL
              rows: 50
             Extra: Using where
     1 row in set (0.00 sec)

Check what would happen without a spatial index:

     mysql> SET @poly =
         -> 'Polygon((30000 15000,
                                    31000 15000,
                                    31000 16000,
                                    30000 16000,
                                    30000 15000))';
     mysql> EXPLAIN SELECT fid,AsText(g) FROM g IGNORE INDEX (g) WHERE
         -> MBRContains(GeomFromText(@poly),g)\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: geom
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: 32376
             Extra: Using where
     1 row in set (0.00 sec)

Executing the *Note `SELECT': select. statement without the spatial
index yields the same result but causes the execution time to rise from
0.00 seconds to 0.46 seconds:

     mysql> SET @poly =
         -> 'Polygon((30000 15000,
                                    31000 15000,
                                    31000 16000,
                                    30000 16000,
                                    30000 15000))';
     mysql> SELECT fid,AsText(g) FROM geom IGNORE INDEX (g) WHERE
         -> MBRContains(GeomFromText(@poly),g);
     +-----+---------------------------------------------------------------+
     | fid | AsText(g)                                                     |
     +-----+---------------------------------------------------------------+
     |   1 | LINESTRING(30250.4 15129.2,30248.8 15138.4,30238.2 15136. ... |
     |   2 | LINESTRING(30220.2 15122.8,30217.2 15137.8,30207.6 15136, ... |
     |   3 | LINESTRING(30179 15114.4,30176.6 15129.4,30167 15128,3016 ... |
     |   4 | LINESTRING(30155.2 15121.4,30140.4 15118.6,30142 15109,30 ... |
     |   5 | LINESTRING(30192.4 15085,30177.6 15082.2,30179.2 15072.4, ... |
     |   6 | LINESTRING(30244 15087,30229 15086.2,30229.4 15076.4,3024 ... |
     |   7 | LINESTRING(30200.6 15059.4,30185.6 15058.6,30186 15048.8, ... |
     |  10 | LINESTRING(30179.6 15017.8,30181 15002.8,30190.8 15003.6, ... |
     |  11 | LINESTRING(30154.2 15000.4,30168.6 15004.8,30166 15014.2, ... |
     |  13 | LINESTRING(30105 15065.8,30108.4 15050.8,30118 15053,3011 ... |
     |  21 | LINESTRING(30350.4 15828.8,30350.6 15845,30333.8 15845,30 ... |
     |  22 | LINESTRING(30350.6 15871.4,30350.6 15887.8,30334 15887.8, ... |
     |  23 | LINESTRING(30350.6 15914.2,30350.6 15930.4,30334 15930.4, ... |
     |  24 | LINESTRING(30290.2 15823,30290.2 15839.4,30273.4 15839.4, ... |
     |  25 | LINESTRING(30291.4 15866.2,30291.6 15882.4,30274.8 15882. ... |
     |  26 | LINESTRING(30291.6 15918.2,30291.6 15934.4,30275 15934.4, ... |
     | 154 | LINESTRING(30276.2 15143.8,30261.4 15141,30263 15131.4,30 ... |
     | 155 | LINESTRING(30269.8 15084,30269.4 15093.4,30258.6 15093,30 ... |
     | 157 | LINESTRING(30128.2 15011,30113.2 15010.2,30113.6 15000.4, ... |
     | 249 | LINESTRING(30337.8 15938.6,30337.8 15946.8,30320.4 15946. ... |
     +-----+---------------------------------------------------------------+
     20 rows in set (0.46 sec)

In future releases, spatial indexes may also be used for optimizing
other functions. See *Note
functions-for-testing-spatial-relations-between-geometric-objects::.


File: manual.info,  Node: mysql-gis-conformance-and-compatibility,  Prev: optimizing-spatial-analysis,  Up: spatial-extensions

11.13.7 MySQL Conformance and Compatibility
-------------------------------------------

MySQL does not yet implement the following GIS features:

   * Additional Metadata Views

     OpenGIS specifications propose several additional metadata views.
     For example, a system view named `GEOMETRY_COLUMNS' contains a
     description of geometry columns, one row for each geometry column
     in the database.

   * The OpenGIS function `Length()' on `LineString' and
     `MultiLineString' currently should be called in MySQL as
     `GLength()'

     The problem is that there is an existing SQL function `Length()'
     that calculates the length of string values, and sometimes it is
     not possible to distinguish whether the function is called in a
     textual or spatial context. We need either to solve this somehow,
     or decide on another function name.


File: manual.info,  Node: precision-math,  Prev: spatial-extensions,  Up: functions

11.14 Precision Math
====================

* Menu:

* precision-math-numbers::       Types of Numeric Values
* precision-math-decimal-changes::  `DECIMAL' Data Type Changes
* precision-math-expressions::   Expression Handling
* precision-math-rounding::      Rounding Behavior
* precision-math-examples::      Precision Math Examples

MySQL 6.0 provides support for precision math: numeric value handling
that results in extremely accurate results and a high degree control
over invalid values. Precision math is based on these two features:

   * SQL modes that control how strict the server is about accepting or
     rejecting invalid data.

   * The MySQL library for fixed-point arithmetic.

These features have several implications for numeric operations:

   * *Precise calculations*: For exact-value numbers, calculations do
     not introduce floating-point errors. Instead, exact precision is
     used. For example, a number such as `.0001' is treated as an exact
     value rather than as an approximation, and summing it 10,000 times
     produces a result of exactly `1', not a value that merely `close'
     to 1.

   * *Well-defined rounding behavior*: For exact-value numbers, the
     result of `ROUND()' depends on its argument, not on environmental
     factors such as how the underlying C library works.

   * *Platform independence*: Operations on exact numeric values are
     the same across different platforms such as Windows and Unix.

   * *Control over handling of invalid values*: Overflow and division
     by zero are detectable and can be treated as errors. For example,
     you can treat a value that is too large for a column as an error
     rather than having the value truncated to lie within the range of
     the column's data type. Similarly, you can treat division by zero
     as an error rather than as an operation that produces a result of
     `NULL'. The choice of which approach to take is determined by the
     setting of the `sql_mode' system variable.

An important result of these features is that MySQL 6.0 provides a high
degree of compliance with standard SQL.

The following discussion covers several aspects of how precision math
works (including possible incompatibilities with older applications).
At the end, some examples are given that demonstrate how MySQL 6.0
handles numeric operations precisely. For information about using the
`sql_mode' system variable to control the SQL mode, see *Note
server-sql-mode::.


File: manual.info,  Node: precision-math-numbers,  Next: precision-math-decimal-changes,  Prev: precision-math,  Up: precision-math

11.14.1 Types of Numeric Values
-------------------------------

The scope of precision math for exact-value operations includes the
exact-value data types (*Note `DECIMAL': numeric-types.  and integer
types) and exact-value numeric literals.  Approximate-value data types
and numeric literals still are handled as floating-point numbers.

Exact-value numeric literals have an integer part or fractional part,
or both. They may be signed. Examples: `1', `.2', `3.4', `-5', `-6.78',
`+9.10'.

Approximate-value numeric literals are represented in scientific
notation with a mantissa and exponent. Either or both parts may be
signed. Examples: `1.2E3', `1.2E-3', `-1.2E3', `-1.2E-3'.

Two numbers that look similar need not be both exact-value or both
approximate-value. For example, `2.34' is an exact-value (fixed-point)
number, whereas `2.34E0' is an approximate-value (floating-point)
number.

The *Note `DECIMAL': numeric-types. data type is a fixed-point type and
calculations are exact. In MySQL, the *Note `DECIMAL': numeric-types.
type has several synonyms: *Note `NUMERIC': numeric-types, *Note `DEC':
numeric-types, *Note `FIXED': numeric-types. The integer types also are
exact-value types.

The *Note `FLOAT': numeric-types. and *Note `DOUBLE': numeric-types.
data types are floating-point types and calculations are approximate.
In MySQL, types that are synonymous with *Note `FLOAT': numeric-types.
or *Note `DOUBLE': numeric-types. are *Note `DOUBLE PRECISION':
numeric-types. and *Note `REAL': numeric-types.


File: manual.info,  Node: precision-math-decimal-changes,  Next: precision-math-expressions,  Prev: precision-math-numbers,  Up: precision-math

11.14.2 `DECIMAL' Data Type Changes
-----------------------------------

This section discusses the characteristics of the *Note `DECIMAL':
numeric-types. data type (and its synonyms) in MySQL 6.0, with
particular regard to the following topics:

   * Maximum number of digits

   * Storage format

   * Storage requirements

   * The non-standard MySQL extension to the upper range of *Note
     `DECIMAL': numeric-types. columns

Possible incompatibilities with applications that are written for older
versions of MySQL are noted throughout this section.

The declaration syntax for a *Note `DECIMAL': numeric-types. column is
`DECIMAL(M,D)'.  The ranges of values for the arguments in MySQL 6.0
are as follows:

   * M is the maximum number of digits (the precision). It has a range
     of 1 to 65. (Older versions of MySQL allowed a range of 1 to 254.)

   * D is the number of digits to the right of the decimal point (the
     scale). It has a range of 0 to 30 and must be no larger than M.

The maximum value of 65 for M means that calculations on *Note
`DECIMAL': numeric-types. values are accurate up to 65 digits. This
limit of 65 digits of precision also applies to exact-value numeric
literals, so the maximum range of such literals is different from
before. (In older versions of MySQL, decimal values could have up to
254 digits. However, calculations were done using floating-point and
thus were approximate, not exact.)

Values for *Note `DECIMAL': numeric-types. columns in MySQL 6.0 are
stored using a binary format that packs nine decimal digits into four
bytes. The storage requirements for the integer and fractional parts of
each value are determined separately. Each multiple of nine digits
requires four bytes, and any digits left over require some fraction of
four bytes. For example, a `DECIMAL(18,9)' column has nine digits on
either side of the decimal point, so the integer part and the
fractional part each require four bytes. A `DECIMAL(20,10)' column has
ten digits on either side of the decimal point. Each part requires four
bytes for nine of the digits, and one byte for the remaining digit.

The storage required for leftover digits is given by the following
table.

*Leftover Digits*  *Number of Bytes*
0                  0
1                  1
2                  1
3                  2
4                  2
5                  3
6                  3
7                  4
8                  4
9                  4

Unlike some older versions of MySQL (prior to 5.0.3), *Note `DECIMAL':
numeric-types. columns in MySQL 6.0 do not store a leading `+'
character or `-' character or leading `0' digits. If you insert
`+0003.1' into a `DECIMAL(5,1)' column, it is stored as `3.1'. For
negative numbers, a literal `-' character is not stored.  Applications
that rely on the older behavior must be modified to account for this
change.

*Note `DECIMAL': numeric-types. columns in MySQL 6.0 do not allow
values larger than the range implied by the column definition. For
example, a `DECIMAL(3,0)' column supports a range of `-999' to `999'. A
`DECIMAL(M,D)' column allows at most M - D digits to the left of the
decimal point. This is not compatible with applications relying on older
versions of MySQL that allowed storing an extra digit in lieu of a `+'
sign.

The SQL standard requires that the precision of `NUMERIC(M,D)' be
_exactly_ M digits. For `DECIMAL(M,D)', the standard requires a
precision of at least M digits but allows more. In MySQL, `DECIMAL(M,D)'
and `NUMERIC(M,D)' are the same, and both have a precision of exactly M
digits.

For more detailed information about porting applications that rely on
the old treatment of the *Note `DECIMAL': numeric-types.  data type,
see the `MySQL 5.0 Reference Manual'.


File: manual.info,  Node: precision-math-expressions,  Next: precision-math-rounding,  Prev: precision-math-decimal-changes,  Up: precision-math

11.14.3 Expression Handling
---------------------------

With precision math, exact-value numbers are used as given whenever
possible. For example, numbers in comparisons are used exactly as given
without a change in value. In strict SQL mode, for *Note `INSERT':
insert. into a column with an exact data type (*Note `DECIMAL':
numeric-types. or integer), a number is inserted with its exact value
if it is within the column range. When retrieved, the value should be
the same as what was inserted. (Without strict mode, truncation for
*Note `INSERT': insert. is allowable.)

Handling of a numeric expression depends on what kind of values the
expression contains:

   * If any approximate values are present, the expression is
     approximate and is evaluated using floating-point arithmetic.

   * If no approximate values are present, the expression contains only
     exact values. If any exact value contains a fractional part (a
     value following the decimal point), the expression is evaluated
     using *Note `DECIMAL': numeric-types. exact arithmetic and has a
     precision of 65 digits. (The term `exact' is subject to the limits
     of what can be represented in binary. For example, `1.0/3.0' can
     be approximated in decimal notation as `.333...', but not written
     as an exact number, so `(1.0/3.0)*3.0' does not evaluate to
     exactly `1.0'.)

   * Otherwise, the expression contains only integer values. The
     expression is exact and is evaluated using integer arithmetic and
     has a precision the same as *Note `BIGINT': numeric-types. (64
     bits).

If a numeric expression contains any strings, they are converted to
double-precision floating-point values and the expression is
approximate.

Inserts into numeric columns are affected by the SQL mode, which is
controlled by the `sql_mode' system variable. (See *Note
server-sql-mode::.) The following discussion mentions strict mode
(selected by the `STRICT_ALL_TABLES' or `STRICT_TRANS_TABLES' mode
values) and `ERROR_FOR_DIVISION_BY_ZERO'.  To turn on all restrictions,
you can simply use `TRADITIONAL' mode, which includes both strict mode
values and `ERROR_FOR_DIVISION_BY_ZERO':

     mysql> SET sql_mode='TRADITIONAL';

If a number is inserted into an exact type column (*Note `DECIMAL':
numeric-types. or integer), it is inserted with its exact value if it
is within the column range.

If the value has too many digits in the fractional part, rounding
occurs and a warning is generated. Rounding is done as described in
*Note precision-math-rounding::.

If the value has too many digits in the integer part, it is too large
and is handled as follows:

   * If strict mode is not enabled, the value is truncated to the
     nearest legal value and a warning is generated.

   * If strict mode is enabled, an overflow error occurs.

Underflow is not detected, so underflow handing is undefined.

By default, division by zero produces a result of `NULL' and no
warning. With the `ERROR_FOR_DIVISION_BY_ZERO' SQL mode enabled, MySQL
handles division by zero differently:

   * If strict mode is not enabled, a warning occurs.

   * If strict mode is enabled, inserts and updates involving division
     by zero are prohibited, and an error occurs.

In other words, inserts and updates involving expressions that perform
division by zero can be treated as errors, but this requires
`ERROR_FOR_DIVISION_BY_ZERO' in addition to strict mode.

Suppose that we have this statement:

     INSERT INTO t SET i = 1/0;

This is what happens for combinations of strict and
`ERROR_FOR_DIVISION_BY_ZERO' modes.

*`sql_mode' Value*                   *Result*
`''' (Default)                       No warning, no error; `i' is set to
                                     `NULL'.
strict                               No warning, no error; `i' is set to
                                     `NULL'.
`ERROR_FOR_DIVISION_BY_ZERO'         Warning, no error; `i' is set to
                                     `NULL'.
strict,`ERROR_FOR_DIVISION_BY_ZERO'  Error condition; no row is inserted.

For inserts of strings into numeric columns, conversion from string to
number is handled as follows if the string has non-numeric contents:

   * A string that does not begin with a number cannot be used as a
     number and produces an error in strict mode, or a warning
     otherwise. _This includes the empty string_.

   * A string that begins with a number can be converted, but the
     trailing non-numeric portion is truncated. If the truncated
     portion contains anything other than spaces, this produces an
     error in strict mode, or a warning otherwise.


File: manual.info,  Node: precision-math-rounding,  Next: precision-math-examples,  Prev: precision-math-expressions,  Up: precision-math

11.14.4 Rounding Behavior
-------------------------

This section discusses precision math rounding for the `ROUND()'
function and for inserts into columns with exact-value types (*Note
`DECIMAL': numeric-types. and integer).

The `ROUND()' function rounds differently depending on whether its
argument is exact or approximate:

   * For exact-value numbers, `ROUND()' uses the `round half up' rule:
     A value with a fractional part of .5 or greater is rounded up to
     the next integer if positive or down to the next integer if
     negative. (In other words, it is rounded away from zero.) A value
     with a fractional part less than .5 is rounded down to the next
     integer if positive or up to the next integer if negative.

   * For approximate-value numbers, the result depends on the C
     library. On many systems, this means that `ROUND()' uses the `round
     to nearest even' rule: A value with any fractional part is rounded
     to the nearest even integer.

The following example shows how rounding differs for exact and
approximate values:

     mysql> SELECT ROUND(2.5), ROUND(25E-1);
     +------------+--------------+
     | ROUND(2.5) | ROUND(25E-1) |
     +------------+--------------+
     | 3          |            2 |
     +------------+--------------+

For inserts into a *Note `DECIMAL': numeric-types. or integer column,
the target is an exact data type, so rounding uses `round half up,'
regardless of whether the value to be inserted is exact or approximate:

     mysql> CREATE TABLE t (d DECIMAL(10,0));
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO t VALUES(2.5),(2.5E0);
     Query OK, 2 rows affected, 2 warnings (0.00 sec)
     Records: 2  Duplicates: 0  Warnings: 2

     mysql> SELECT d FROM t;
     +------+
     | d    |
     +------+
     | 3    |
     | 3    |
     +------+


File: manual.info,  Node: precision-math-examples,  Prev: precision-math-rounding,  Up: precision-math

11.14.5 Precision Math Examples
-------------------------------

This section provides some examples that show precision math query
results in MySQL 6.0.

*Example 1*. Numbers are used with their exact value as given when
possible:

     mysql> SELECT .1 + .2 = .3;
     +--------------+
     | .1 + .2 = .3 |
     +--------------+
     |            1 |
     +--------------+

For floating-point values, results are inexact:

     mysql> SELECT .1E0 + .2E0 = .3E0;
     +--------------------+
     | .1E0 + .2E0 = .3E0 |
     +--------------------+
     |                  0 |
     +--------------------+

Another way to see the difference in exact and approximate value
handling is to add a small number to a sum many times. Consider the
following stored procedure, which adds `.0001' to a variable 1,000
times.

     CREATE PROCEDURE p ()
     BEGIN
       DECLARE i INT DEFAULT 0;
       DECLARE d DECIMAL(10,4) DEFAULT 0;
       DECLARE f FLOAT DEFAULT 0;
       WHILE i < 10000 DO
         SET d = d + .0001;
         SET f = f + .0001E0;
         SET i = i + 1;
       END WHILE;
       SELECT d, f;
     END;

The sum for both `d' and `f' logically should be 1, but that is true
only for the decimal calculation. The floating-point calculation
introduces small errors:

     +--------+------------------+
     | d      | f                |
     +--------+------------------+
     | 1.0000 | 0.99999999999991 |
     +--------+------------------+

*Example 2*. Multiplication is performed with the scale required by
standard SQL. That is, for two numbers X1 and X2 that have scale S1 and
S2, the scale of the result is `S1 + S2':

     mysql> SELECT .01 * .01;
     +-----------+
     | .01 * .01 |
     +-----------+
     | 0.0001    |
     +-----------+

*Example 3*. Rounding behavior is well-defined:

Rounding behavior (for example, with the `ROUND()' function) is
independent of the implementation of the underlying C library, which
means that results are consistent from platform to platform.

Rounding for exact-value columns (*Note `DECIMAL': numeric-types. and
integer) and exact-valued numbers uses the `round half up' rule.
Values with a fractional part of .5 or greater are rounded away from
zero to the nearest integer, as shown here:

     mysql> SELECT ROUND(2.5), ROUND(-2.5);
     +------------+-------------+
     | ROUND(2.5) | ROUND(-2.5) |
     +------------+-------------+
     | 3          | -3          |
     +------------+-------------+

However, rounding for floating-point values uses the C library, which
on many systems uses the `round to nearest even' rule. Values with any
fractional part on such systems are rounded to the nearest even integer:

     mysql> SELECT ROUND(2.5E0), ROUND(-2.5E0);
     +--------------+---------------+
     | ROUND(2.5E0) | ROUND(-2.5E0) |
     +--------------+---------------+
     |            2 |            -2 |
     +--------------+---------------+

*Example 4*. In strict mode, inserting a value that is too large
results in overflow and causes an error, rather than truncation to a
legal value.

When MySQL is not running in strict mode, truncation to a legal value
occurs:

     mysql> SET sql_mode='';
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t (i TINYINT);
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO t SET i = 128;
     Query OK, 1 row affected, 1 warning (0.00 sec)

     mysql> SELECT i FROM t;
     +------+
     | i    |
     +------+
     |  127 |
     +------+
     1 row in set (0.00 sec)

However, an overflow condition occurs if strict mode is in effect:

     mysql> SET sql_mode='STRICT_ALL_TABLES';
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t (i TINYINT);
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO t SET i = 128;
     ERROR 1264 (22003): Out of range value adjusted for column 'i' at row 1

     mysql> SELECT i FROM t;
     Empty set (0.00 sec)

*Example 5*: In strict mode and with `ERROR_FOR_DIVISION_BY_ZERO' set,
division by zero causes an error, and not a result of `NULL'.

In non-strict mode, division by zero has a result of `NULL':

     mysql> SET sql_mode='';
     Query OK, 0 rows affected (0.01 sec)

     mysql> CREATE TABLE t (i TINYINT);
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO t SET i = 1 / 0;
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT i FROM t;
     +------+
     | i    |
     +------+
     | NULL |
     +------+
     1 row in set (0.03 sec)

However, division by zero is an error if the proper SQL modes are in
effect:

     mysql> SET sql_mode='STRICT_ALL_TABLES,ERROR_FOR_DIVISION_BY_ZERO';
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t (i TINYINT);
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO t SET i = 1 / 0;
     ERROR 1365 (22012): Division by 0

     mysql> SELECT i FROM t;
     Empty set (0.01 sec)

*Example 6*. Prior to MySQL 5.0.3 (before precision math was
introduced), exact-value and approximate-value literals both are
converted to double-precision floating-point values:

     mysql> SELECT VERSION();
     +------------+
     | VERSION()  |
     +------------+
     | 4.1.18-log |
     +------------+
     1 row in set (0.01 sec)

     mysql> CREATE TABLE t SELECT 2.5 AS a, 25E-1 AS b;
     Query OK, 1 row affected (0.07 sec)
     Records: 1  Duplicates: 0  Warnings: 0

     mysql> DESCRIBE t;
     +-------+-------------+------+-----+---------+-------+
     | Field | Type        | Null | Key | Default | Extra |
     +-------+-------------+------+-----+---------+-------+
     | a     | double(3,1) |      |     | 0.0     |       |
     | b     | double      |      |     | 0       |       |
     +-------+-------------+------+-----+---------+-------+
     2 rows in set (0.04 sec)

As of MySQL 5.0.3, the approximate-value literal still is converted to
floating-point, but the exact-value literal is handled as *Note
`DECIMAL': numeric-types.:

     mysql> SELECT VERSION();
     +-----------------+
     | VERSION()       |
     +-----------------+
     | 5.1.6-alpha-log |
     +-----------------+
     1 row in set (0.11 sec)

     mysql> CREATE TABLE t SELECT 2.5 AS a, 25E-1 AS b;
     Query OK, 1 row affected (0.01 sec)
     Records: 1  Duplicates: 0  Warnings: 0

     mysql> DESCRIBE t;
     +-------+-----------------------+------+-----+---------+-------+
     | Field | Type                  | Null | Key | Default | Extra |
     +-------+-----------------------+------+-----+---------+-------+
     | a     | decimal(2,1) unsigned | NO   |     | 0.0     |       |
     | b     | double                | NO   |     | 0       |       |
     +-------+-----------------------+------+-----+---------+-------+
     2 rows in set (0.01 sec)

*Example 7*. If the argument to an aggregate function is an exact
numeric type, the result is also an exact numeric type, with a scale at
least that of the argument.

Consider these statements:

     mysql> CREATE TABLE t (i INT, d DECIMAL, f FLOAT);
     mysql> INSERT INTO t VALUES(1,1,1);
     mysql> CREATE TABLE y SELECT AVG(i), AVG(d), AVG(f) FROM t;

Result before MySQL 5.0.3 (prior to the introduction of precision math
in MySQL):

     mysql> DESCRIBE y;
     +--------+--------------+------+-----+---------+-------+
     | Field  | Type         | Null | Key | Default | Extra |
     +--------+--------------+------+-----+---------+-------+
     | AVG(i) | double(17,4) | YES  |     | NULL    |       |
     | AVG(d) | double(17,4) | YES  |     | NULL    |       |
     | AVG(f) | double       | YES  |     | NULL    |       |
     +--------+--------------+------+-----+---------+-------+

The result is a double no matter the argument type.

Result as of MySQL 5.0.3:

     mysql> DESCRIBE y;
     +--------+---------------+------+-----+---------+-------+
     | Field  | Type          | Null | Key | Default | Extra |
     +--------+---------------+------+-----+---------+-------+
     | AVG(i) | decimal(14,4) | YES  |     | NULL    |       |
     | AVG(d) | decimal(14,4) | YES  |     | NULL    |       |
     | AVG(f) | double        | YES  |     | NULL    |       |
     +--------+---------------+------+-----+---------+-------+

The result is a double only for the floating-point argument. For exact
type arguments, the result is also an exact type.


File: manual.info,  Node: sql-syntax,  Next: storage-engines,  Prev: functions,  Up: Top

12 SQL Statement Syntax
***********************

* Menu:

* sql-syntax-data-definition::   Data Definition Statements
* sql-syntax-data-manipulation::  Data Manipulation Statements
* sql-syntax-utility::           MySQL Utility Statements
* sql-syntax-transactions::      MySQL Transactional and Locking Statements
* sql-syntax-server-administration::  Database Administration Statements
* sql-syntax-replication::       Replication Statements
* sql-syntax-prepared-statements::  SQL Syntax for Prepared Statements
* sql-syntax-compound-statements::  MySQL Compound-Statement Syntax

This chapter describes the syntax for the SQL statements supported by
MySQL.


File: manual.info,  Node: sql-syntax-data-definition,  Next: sql-syntax-data-manipulation,  Prev: sql-syntax,  Up: sql-syntax

12.1 Data Definition Statements
===============================

* Menu:

* alter-database::               `ALTER DATABASE' Syntax
* alter-event::                  `ALTER EVENT' Syntax
* alter-function::               `ALTER FUNCTION' Syntax
* alter-procedure::              `ALTER PROCEDURE' Syntax
* alter-server::                 `ALTER SERVER' Syntax
* alter-table::                  `ALTER TABLE' Syntax
* alter-view::                   `ALTER VIEW' Syntax
* create-database::              `CREATE DATABASE' Syntax
* create-event::                 `CREATE EVENT' Syntax
* create-function::              `CREATE FUNCTION' Syntax
* create-index::                 `CREATE INDEX' Syntax
* create-procedure::             `CREATE PROCEDURE' and `CREATE FUNCTION' Syntax
* create-server::                `CREATE SERVER' Syntax
* create-table::                 `CREATE TABLE' Syntax
* create-trigger::               `CREATE TRIGGER' Syntax
* create-view::                  `CREATE VIEW' Syntax
* drop-database::                `DROP DATABASE' Syntax
* drop-event::                   `DROP EVENT' Syntax
* drop-function::                `DROP FUNCTION' Syntax
* drop-index::                   `DROP INDEX' Syntax
* drop-procedure::               `DROP PROCEDURE' and `DROP FUNCTION' Syntax
* drop-server::                  `DROP SERVER' Syntax
* drop-table::                   `DROP TABLE' Syntax
* drop-trigger::                 `DROP TRIGGER' Syntax
* drop-view::                    `DROP VIEW' Syntax
* rename-table::                 `RENAME TABLE' Syntax


File: manual.info,  Node: alter-database,  Next: alter-event,  Prev: sql-syntax-data-definition,  Up: sql-syntax-data-definition

12.1.1 `ALTER DATABASE' Syntax
------------------------------

     ALTER {DATABASE | SCHEMA} [DB_NAME]
         ALTER_SPECIFICATION ...
     ALTER {DATABASE | SCHEMA} DB_NAME
         UPGRADE DATA DIRECTORY NAME

     ALTER_SPECIFICATION:
         [DEFAULT] CHARACTER SET [=] CHARSET_NAME
       | [DEFAULT] COLLATE [=] COLLATION_NAME

*Note `ALTER DATABASE': alter-database. enables you to change the
overall characteristics of a database. These characteristics are stored
in the `db.opt' file in the database directory. To use *Note `ALTER
DATABASE': alter-database, you need the `ALTER' privilege on the
database.  *Note `ALTER SCHEMA': alter-database. is a synonym for *Note
`ALTER DATABASE': alter-database.

The `CHARACTER SET' clause changes the default database character set.
The `COLLATE' clause changes the default database collation. *Note
charset::, discusses character set and collation names.

You can see what character sets and collations are available using,
respectively, the *Note `SHOW CHARACTER SET': show-character-set. and
*Note `SHOW COLLATION': show-collation.  statements. See *Note
show-character-set::, and *Note show-collation::, for more information.

The database name can be omitted from the first syntax, in which case
the statement applies to the default database.

The syntax that includes the `UPGRADE DATA DIRECTORY NAME' clause
updates the name of the directory associated with the database to use
the encoding implemented in MySQL 5.1 for mapping database names to
database directory names (see *Note identifier-mapping::). This clause
is for use under these conditions:

   * It is intended when upgrading MySQL to 5.1 or later from older
     versions.

   * It is intended to update a database directory name to the current
     encoding format if the name contains special characters that need
     encoding.

   * The statement is used by *Note `mysqlcheck': mysqlcheck. (as
     invoked by *Note `mysql_upgrade': mysql-upgrade.).

For example,if a database in MySQL 5.0 has a name of `a-b-c', the name
contains instance of the ``-'' character. In 5.0, the database
directory is also named `a-b-c', which is not necessarily safe for all
file systems. In MySQL 5.1 and up, the same database name is encoded as
`a@002db@002dc' to produce a file system-neutral directory name.

When a MySQL installation is upgraded to MySQL 5.1 or later from an
older version,the server displays a name such as `a-b-c' (which is in
the old format) as `#mysql50#a-b-c', and you must refer to the name
using the `#mysql50#' prefix. Use `UPGRADE DATA DIRECTORY NAME' in this
case to explicitly tell the server to re-encode the database directory
name to the current encoding format:

     ALTER DATABASE `#mysql50#a-b-c` UPGRADE DATA DIRECTORY NAME;

After executing this statement, you can refer to the database as
`a-b-c' without the special `#mysql50#' prefix.

MySQL Enterprise

In a production environment, alteration of a database is not a common
occurrence and may indicate a security breach. Advisors provided as
part of the MySQL Enterprise Monitor automatically alert you when data
definition statements are issued. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: alter-event,  Next: alter-function,  Prev: alter-database,  Up: sql-syntax-data-definition

12.1.2 `ALTER EVENT' Syntax
---------------------------

     ALTER
         [DEFINER = { USER | CURRENT_USER }]
         EVENT EVENT_NAME
         [ON SCHEDULE SCHEDULE]
         [ON COMPLETION [NOT] PRESERVE]
         [RENAME TO NEW_EVENT_NAME]
         [ENABLE | DISABLE | DISABLE ON SLAVE]
         [COMMENT 'COMMENT']
         [DO SQL_STATEMENT]

The *Note `ALTER EVENT': alter-event. statement is used to change one
or more of the characteristics of an existing event without the need to
drop and recreate it. The syntax for each of the `DEFINER', `ON
SCHEDULE', `ON COMPLETION', `COMMENT', `ENABLE' / `DISABLE', and *Note
`DO': do. clauses is exactly the same as when used with *Note `CREATE
EVENT': create-event. (See *Note create-event::.)

Any user can alter an event defined on a database for which that user
has the `EVENT' privilege. When a user executes a successful *Note
`ALTER EVENT': alter-event. statement, that user becomes the definer
for the affected event.

*Note `ALTER EVENT': alter-event. works only with an existing event:

     mysql> ALTER EVENT no_such_event
          >     ON SCHEDULE
          >       EVERY '2:3' DAY_HOUR;
     `ERROR 1517 (HY000): Unknown event 'no_such_event''

In each of the following examples, assume that the event named
`myevent' is defined as shown here:

     CREATE EVENT myevent
         ON SCHEDULE
           EVERY 6 HOUR
         COMMENT 'A sample comment.'
         DO
           UPDATE myschema.mytable SET mycol = mycol + 1;

The following statement changes the schedule for `myevent' from once
every six hours starting immediately to once every twelve hours,
starting four hours from the time the statement is run:

     ALTER EVENT myevent
         ON SCHEDULE
           EVERY 12 HOUR
         STARTS CURRENT_TIMESTAMP + INTERVAL 4 HOUR;

It is possible to change multiple characteristics of an event in a
single statement. This example changes the SQL statement executed by
`myevent' to one that deletes all records from `mytable'; it also
changes the schedule for the event such that it executes once, one day
after this *Note `ALTER EVENT': alter-event. statement is run.

     ALTER TABLE myevent
         ON SCHEDULE
           AT CURRENT_TIMESTAMP + INTERVAL 1 DAY
         DO
           TRUNCATE TABLE myschema.mytable;

It is necessary to include only those options in an *Note `ALTER
EVENT': alter-event. statement which correspond to characteristics that
you actually wish to change; options which are omitted retain their
existing values. This includes any default values for *Note `CREATE
EVENT': create-event. such as `ENABLE'.

To disable `myevent', use this *Note `ALTER EVENT': alter-event.
statement:

     ALTER EVENT myevent
         DISABLE;

A third value may also appear in place of `ENABLED' or `DISABLED';
`DISABLE ON SLAVE' is used on a replication slave to indicate an event
which was created on the master and replicated to the slave, but which
is not executed on the slave.  Normally, `DISABLE ON SLAVE' is set
automatically as required; however, there are some circumstances under
which you may want or need to change it manually. See *Note
replication-features-invoked::, for more information.

The `ON SCHEDULE' clause may use expressions involving built-in MySQL
functions and user variables to obtain any of the TIMESTAMP or INTERVAL
values which it contains. You may not use stored functions or
user-defined functions in such expressions, nor may you use any table
references; however, you may use `SELECT FROM DUAL'. This is true for
both *Note `ALTER EVENT': alter-event. and *Note `CREATE EVENT':
create-event. statements. References to stored functions, user-defined
functions, and tables in such cases are specifically disallowed, and
fail with an error (see Bug#22830 (http://bugs.mysql.com/22830)).

An *Note `ALTER EVENT': alter-event. statement that contains another
*Note `ALTER EVENT': alter-event.  statement in its *Note `DO': do.
clause appears to succeed; however, when the server attempts to execute
the resulting scheduled event, the execution fails with an error.

To rename an event, use the *Note `ALTER EVENT': alter-event.
statement's `RENAME TO' clause.  This statement renames the event
`myevent' to `yourevent':

     ALTER EVENT myevent
         RENAME TO yourevent;

You can also move an event to a different database using `ALTER EVENT
... RENAME TO ...' and `DB_NAME.EVENT_NAME' notation, as shown here:

     ALTER EVENT olddb.myevent
         RENAME TO newdb.myevent;

To execute the previous statement, the user executing it must have the
`EVENT' privilege on both the `olddb' and `newdb' databases.

*Note*:

There is no `RENAME EVENT' statement.


File: manual.info,  Node: alter-function,  Next: alter-procedure,  Prev: alter-event,  Up: sql-syntax-data-definition

12.1.3 `ALTER FUNCTION' Syntax
------------------------------

     ALTER FUNCTION FUNC_NAME [CHARACTERISTIC ...]

     CHARACTERISTIC:
         { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA }
       | SQL SECURITY { DEFINER | INVOKER }
       | COMMENT 'STRING'

This statement can be used to change the characteristics of a stored
function. More than one change may be specified in an *Note `ALTER
FUNCTION': alter-function. statement. However, you cannot change the
parameters or body of a stored function using this statement; to make
such changes, you must drop and re-create the function using *Note
`DROP FUNCTION': drop-function. and *Note `CREATE FUNCTION':
create-function.

You must have the `ALTER ROUTINE' privilege for the function. (That
privilege is granted automatically to the function creator.) If binary
logging is enabled, the *Note `ALTER FUNCTION': alter-function.
statement might also require the `SUPER' privilege, as described in
*Note stored-programs-logging::.


File: manual.info,  Node: alter-procedure,  Next: alter-server,  Prev: alter-function,  Up: sql-syntax-data-definition

12.1.4 `ALTER PROCEDURE' Syntax
-------------------------------

     ALTER PROCEDURE PROC_NAME [CHARACTERISTIC ...]

     CHARACTERISTIC:
         { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA }
       | SQL SECURITY { DEFINER | INVOKER }
       | COMMENT 'STRING'

This statement can be used to change the characteristics of a stored
procedure. More than one change may be specified in an *Note `ALTER
PROCEDURE': alter-procedure. statement. However, you cannot change the
parameters or body of a stored procedure using this statement; to make
such changes, you must drop and re-create the procedure using *Note
`DROP PROCEDURE': drop-procedure. and *Note `CREATE PROCEDURE':
create-procedure.

You must have the `ALTER ROUTINE' privilege for the procedure. (That
privilege is granted automatically to the procedure creator.)


File: manual.info,  Node: alter-server,  Next: alter-table,  Prev: alter-procedure,  Up: sql-syntax-data-definition

12.1.5 `ALTER SERVER' Syntax
----------------------------

     ALTER SERVER  SERVER_NAME
         OPTIONS (OPTION [, OPTION] ...)

Alters the server information for `SERVER_NAME', adjusting the
specified options as per the *Note `CREATE SERVER': create-server.
command. See *Note create-server::. The corresponding fields in the
`mysql.servers' table are updated accordingly.  This statement requires
the `SUPER' privilege.

For example, to update the `USER' option:

     ALTER SERVER s OPTIONS (USER 'sally');

*Note `ALTER SERVER': alter-server. does not cause an automatic commit.


File: manual.info,  Node: alter-table,  Next: alter-view,  Prev: alter-server,  Up: sql-syntax-data-definition

12.1.6 `ALTER TABLE' Syntax
---------------------------

     ALTER [IGNORE] TABLE TBL_NAME
         ALTER_SPECIFICATION [, ALTER_SPECIFICATION] ...

     ALTER_SPECIFICATION:
         TABLE_OPTION ...
       | ADD [COLUMN] COL_NAME COLUMN_DEFINITION
             [FIRST | AFTER COL_NAME ]
       | ADD [COLUMN] (COL_NAME COLUMN_DEFINITION,...)
       | ADD {INDEX|KEY} [INDEX_NAME]
             [INDEX_TYPE] (INDEX_COL_NAME,...) [INDEX_OPTION] ...
       | ADD [CONSTRAINT [SYMBOL]] PRIMARY KEY
             [INDEX_TYPE] (INDEX_COL_NAME,...) [INDEX_OPTION] ...
       | ADD [CONSTRAINT [SYMBOL]]
             UNIQUE [INDEX|KEY] [INDEX_NAME]
             [INDEX_TYPE] (INDEX_COL_NAME,...) [INDEX_OPTION] ...
       | ADD FULLTEXT [INDEX|KEY] [INDEX_NAME]
             (INDEX_COL_NAME,...) [INDEX_OPTION] ...
       | ADD SPATIAL [INDEX|KEY] [INDEX_NAME]
             (INDEX_COL_NAME,...) [INDEX_OPTION] ...
       | ADD [CONSTRAINT [SYMBOL]]
             FOREIGN KEY [INDEX_NAME] (INDEX_COL_NAME,...)
             REFERENCE_DEFINITION
       | ALTER [COLUMN] COL_NAME {SET DEFAULT LITERAL | DROP DEFAULT}
       | CHANGE [COLUMN] OLD_COL_NAME NEW_COL_NAME COLUMN_DEFINITION
             [FIRST|AFTER COL_NAME]
       | MODIFY [COLUMN] COL_NAME COLUMN_DEFINITION
             [FIRST | AFTER COL_NAME]
       | DROP [COLUMN] COL_NAME
       | DROP PRIMARY KEY
       | DROP {INDEX|KEY} INDEX_NAME
       | DROP FOREIGN KEY FK_SYMBOL
       | DISABLE KEYS
       | ENABLE KEYS
       | RENAME [TO] NEW_TBL_NAME
       | ORDER BY COL_NAME [, COL_NAME] ...
       | CONVERT TO CHARACTER SET CHARSET_NAME [COLLATE COLLATION_NAME]
       | [DEFAULT] CHARACTER SET [=] CHARSET_NAME [COLLATE [=] COLLATION_NAME]
       | DISCARD TABLESPACE
       | IMPORT TABLESPACE
       | PARTITION_OPTIONS
       | ADD PARTITION (PARTITION_DEFINITION)
       | DROP PARTITION PARTITION_NAMES
       | COALESCE PARTITION NUMBER
       | REORGANIZE PARTITION PARTITION_NAMES INTO (PARTITION_DEFINITIONS)
       | ANALYZE PARTITION PARTITION_NAMES
       | CHECK PARTITION PARTITION_NAMES
       | OPTIMIZE PARTITION PARTITION_NAMES
       | REBUILD PARTITION PARTITION_NAMES
       | REPAIR PARTITION PARTITION_NAMES
       | REMOVE PARTITIONING

     INDEX_COL_NAME:
         COL_NAME [(LENGTH)] [ASC | DESC]

     INDEX_TYPE:
         USING {BTREE | HASH | RTREE}

     INDEX_OPTION:
         KEY_BLOCK_SIZE [=] VALUE
       | INDEX_TYPE
       | WITH PARSER PARSER_NAME
       | COMMENT 'STRING'

*Note `ALTER TABLE': alter-table. enables you to change the structure
of an existing table. For example, you can add or delete columns,
create or destroy indexes, change the type of existing columns, or
rename columns or the table itself. You can also change the comment for
the table and type of the table.

The syntax for many of the allowable alterations is similar to clauses
of the *Note `CREATE TABLE': create-table.  statement. See *Note
create-table::, for more information.

Some operations may result in warnings if attempted on a table for
which the storage engine does not support the operation. These warnings
can be displayed with *Note `SHOW WARNINGS': show-warnings. See *Note
show-warnings::.

In most cases, *Note `ALTER TABLE': alter-table. works by making a
temporary copy of the original table. The alteration is performed on
the copy, and then the original table is deleted and the new one is
renamed. While *Note `ALTER TABLE': alter-table. is executing, the
original table is readable by other sessions. Updates and writes to the
table are stalled until the new table is ready, and then are
automatically redirected to the new table without any failed updates.
The temporary table is created in the database directory of the new
table. This can be different from the database directory of the
original table if *Note `ALTER TABLE': alter-table. is renaming the
table to a different database.

In some cases, no temporary table is necessary:

   * Alterations that modify only table metadata and not table data can
     be made immediately by altering the table's `.frm' file and not
     touching table contents. The following changes are fast
     alterations that can be made this way:

        * Renaming a column or index.

        * Changing the default value of a column.

        * Changing the definition of an *Note `ENUM': enum. or *Note
          `SET': set. column by adding new enumeration or set members
          to the _end_ of the list of valid member values.

     In some cases, an operation such as changing a `VARCHAR(10)'
     column to `VARCHAR(15)' may be immediate, but this depends on the
     storage engine for the table. A change such as `VARCHAR(10)' to a
     length greater than 255 is not immediate because data values must
     be modified from using one byte to store the length to using two
     bytes.

   * If you use `ALTER TABLE TBL_NAME RENAME TO NEW_TBL_NAME' without
     any other options, MySQL simply renames any files that correspond
     to the table TBL_NAME. (You can also use the *Note `RENAME TABLE':
     rename-table.  statement to rename tables. See *Note
     rename-table::.) Any privileges granted specifically for the
     renamed table are not migrated to the new name. They must be
     changed manually.

   * `ALTER TABLE ... ADD PARTITION' creates no temporary table. `ADD'
     or `DROP' operations for `RANGE' or `LIST' partitions are
     immediate operations or nearly so. `ADD' or `COALESCE' operations
     for `HASH' or `KEY' partitions copy data between changed
     partitions; unless `LINEAR HASH' or `LINEAR KEY' was used, this is
     much the same as creating a new table (although the operation is
     done partition by partition).  `REORGANIZE' operations copy only
     changed partitions and do not touch unchanged ones.

If other cases, MySQL creates a temporary table, even if the data
wouldn't strictly need to be copied. For `MyISAM' tables, you can speed
up the index re-creation operation (which is the slowest part of the
alteration process) by setting the `myisam_sort_buffer_size' system
variable to a high value.

For information on troubleshooting *Note `ALTER TABLE': alter-table,
see *Note alter-table-problems::.

   * To use *Note `ALTER TABLE': alter-table, you need `ALTER',
     `INSERT', and `CREATE' privileges for the table.

   * `ADD INDEX' and *Note `DROP INDEX': drop-index. operations are
     performed online when the indexes are on variable-width columns
     only.

     Online operations are non-copying; that is, they do not require
     that indexes be re-created.

     The server determines automatically whether an `ADD INDEX' or
     *Note `DROP INDEX': drop-index.  operation can be (and is)
     performed online or offline; if the column is of a variable-width
     data type, then the operation is performed online. It is not
     possible to override the server behavior in this regard.

     *Note*:

     The *Note `CREATE INDEX': create-index. and *Note `DROP INDEX':
     drop-index. statements also support online operations. See *Note
     create-index::, and *Note drop-index::, for more information.

   * `IGNORE' is a MySQL extension to standard SQL. It controls how
     *Note `ALTER TABLE': alter-table. works if there are duplicates on
     unique keys in the new table or if warnings occur when strict mode
     is enabled. If `IGNORE' is not specified, the copy is aborted and
     rolled back if duplicate-key errors occur.  If `IGNORE' is
     specified, only the first row is used of rows with duplicates on a
     unique key, The other conflicting rows are deleted. Incorrect
     values are truncated to the closest matching acceptable value.

   * TABLE_OPTION signifies a table option of the kind that can be used
     in the *Note `CREATE TABLE': create-table. statement, such as
     `ENGINE', `AUTO_INCREMENT', or `AVG_ROW_LENGTH'.  (*Note
     create-table::, lists all table options.)  However, *Note `ALTER
     TABLE': alter-table. ignores the `DATA DIRECTORY' and `INDEX
     DIRECTORY' table options.

     For example, to convert a table to be an `InnoDB' table, use this
     statement:

          ALTER TABLE t1 ENGINE = InnoDB;

     The outcome of attempting to change a table's storage engine is
     affected by whether the desired storage engine is available and
     the setting of the `NO_ENGINE_SUBSTITUTION' SQL mode, as described
     in *Note server-sql-mode::.

     To prevent inadvertent loss of data, *Note `ALTER TABLE':
     alter-table. cannot be used to change the storage engine of a
     table to `MERGE' or `BLACKHOLE'.

     To change the value of the `AUTO_INCREMENT' counter to be used for
     new rows, do this:

          ALTER TABLE t2 AUTO_INCREMENT = VALUE;

     You cannot reset the counter to a value less than or equal to any
     that have already been used. For `MyISAM', if the value is less
     than or equal to the maximum value currently in the
     `AUTO_INCREMENT' column, the value is reset to the current maximum
     plus one. For `InnoDB', _if the value is less than the current
     maximum value in the column, no error occurs and the current
     sequence value is not changed._

   * You can issue multiple `ADD', `ALTER', `DROP', and `CHANGE'
     clauses in a single *Note `ALTER TABLE': alter-table. statement,
     separated by commas. This is a MySQL extension to standard SQL,
     which allows only one of each clause per *Note `ALTER TABLE':
     alter-table. statement. For example, to drop multiple columns in a
     single statement, do this:

          ALTER TABLE t2 DROP COLUMN c, DROP COLUMN d;

   * `CHANGE COL_NAME', `DROP COL_NAME', and *Note `DROP INDEX':
     drop-index. are MySQL extensions to standard SQL.

   * `MODIFY' is an Oracle extension to *Note `ALTER TABLE':
     alter-table.

   * The word `COLUMN' is optional and can be omitted.

   * COLUMN_DEFINITION clauses use the same syntax for `ADD' and
     `CHANGE' as for *Note `CREATE TABLE': create-table. See *Note
     create-table::.

   * You can rename a column using a `CHANGE OLD_COL_NAME NEW_COL_NAME
     COLUMN_DEFINITION' clause.  To do so, specify the old and new
     column names and the definition that the column currently has. For
     example, to rename an *Note `INTEGER': numeric-types. column from
     `a' to `b', you can do this:

          ALTER TABLE t1 CHANGE a b INTEGER;

     If you want to change a column's type but not the name, `CHANGE'
     syntax still requires an old and new column name, even if they are
     the same. For example:

          ALTER TABLE t1 CHANGE b b BIGINT NOT NULL;

     You can also use `MODIFY' to change a column's type without
     renaming it:

          ALTER TABLE t1 MODIFY b BIGINT NOT NULL;

     When you use `CHANGE' or `MODIFY', COLUMN_DEFINITION must include
     the data type and all attributes that should apply to the new
     column, other than index attributes such as `PRIMARY KEY' or
     `UNIQUE'. Attributes present in the original definition but not
     specified for the new definition are not carried forward. Suppose
     a column `col1' is defined as `INT UNSIGNED DEFAULT 1 COMMENT 'my
     column'' and you modify the column as follows:

          ALTER TABLE t1 MODIFY col1 BIGINT;

     The resulting column will be defined as `BIGINT', but will not
     include the attributes `UNSIGNED DEFAULT 1 COMMENT 'my column''. To
     retain them, the statement should be:

          ALTER TABLE t1 MODIFY col1 BIGINT UNSIGNED DEFAULT 1 COMMENT 'my column';

   * When you change a data type using `CHANGE' or `MODIFY', MySQL
     tries to convert existing column values to the new type as well as
     possible.

     *Warning*:

     This conversion may result in alteration of data. For example, if
     you shorten a string column, values may be truncated. To prevent
     the operation from succeeding if conversions to the new data type
     would result in loss of data, enable strict SQL mode before using
     *Note `ALTER TABLE': alter-table. (see *Note server-sql-mode::).

   * To add a column at a specific position within a table row, use
     `FIRST' or `AFTER COL_NAME'. The default is to add the column
     last. You can also use `FIRST' and `AFTER' in `CHANGE' or `MODIFY'
     operations to reorder columns within a table.

   * `ALTER ... SET DEFAULT' or `ALTER ...  DROP DEFAULT' specify a new
     default value for a column or remove the old default value,
     respectively. If the old default is removed and the column can be
     `NULL', the new default is `NULL'. If the column cannot be `NULL',
     MySQL assigns a default value as described in *Note
     data-type-defaults::.

   * *Note `DROP INDEX': drop-index. removes an index.  This is a MySQL
     extension to standard SQL. See *Note drop-index::. If you are
     unsure of the index name, use `SHOW INDEX FROM TBL_NAME'.

   * If columns are dropped from a table, the columns are also removed
     from any index of which they are a part. If all columns that make
     up an index are dropped, the index is dropped as well. If you use
     `CHANGE' or `MODIFY' to shorten a column for which an index exists
     on the column, and the resulting column length is less than the
     index length, MySQL shortens the index automatically.

   * If a table contains only one column, the column cannot be dropped.
     If what you intend is to remove the table, use *Note `DROP TABLE':
     drop-table. instead.

   * `DROP PRIMARY KEY' drops the primary key. If there is no primary
     key, an error occurs.

     If you add a `UNIQUE INDEX' or `PRIMARY KEY' to a table, it is
     stored before any non-unique index so that MySQL can detect
     duplicate keys as early as possible.

   * Some storage engines allow you to specify an index type when
     creating an index. The syntax for the INDEX_TYPE specifier is
     `USING TYPE_NAME'.  For details about `USING', see *Note
     create-index::. The index type should be specified after the
     column list.

     INDEX_OPTION values specify additional options for an index.
     `USING' is one such option. For details about allowable
     INDEX_OPTION values, see *Note create-index::.

   * After an *Note `ALTER TABLE': alter-table. statement, it may be
     necessary to run *Note `ANALYZE TABLE': analyze-table. to update
     index cardinality information. See *Note show-index::.

   * `ORDER BY' enables you to create the new table with the rows in a
     specific order. Note that the table does not remain in this order
     after inserts and deletes. This option is useful primarily when
     you know that you are mostly to query the rows in a certain order
     most of the time. By using this option after major changes to the
     table, you might be able to get higher performance. In some cases,
     it might make sorting easier for MySQL if the table is in order by
     the column that you want to order it by later.

     `ORDER BY' syntax allows for one or more column names to be
     specified for sorting, each of which optionally can be followed by
     `ASC' or `DESC' to indicate ascending or descending sort order,
     respectively. The default is ascending order. Only column names
     are allowed as sort criteria; arbitrary expressions are not
     allowed.

     `ORDER BY' does not make sense for `InnoDB' tables that contain a
     user-defined clustered index (`PRIMARY KEY' or `NOT NULL UNIQUE'
     index).  `InnoDB' always orders table rows according to such an
     index if one is present.

     *Note*:

     When used on a partitioned table, `ALTER TABLE ...  ORDER BY'
     orders rows within each partition only.

   * If you use *Note `ALTER TABLE': alter-table. on a `MyISAM' table,
     all non-unique indexes are created in a separate batch (as for
     *Note `REPAIR TABLE': repair-table.). This should make *Note
     `ALTER TABLE': alter-table. much faster when you have many indexes.

     This feature can be activated explicitly for a `MyISAM' table.
     `ALTER TABLE ...  DISABLE KEYS' tells MySQL to stop updating
     non-unique indexes. `ALTER TABLE ... ENABLE KEYS' then should be
     used to re-create missing indexes. MySQL does this with a special
     algorithm that is much faster than inserting keys one by one, so
     disabling keys before performing bulk insert operations should
     give a considerable speedup. Using `ALTER TABLE ... DISABLE KEYS'
     requires the `INDEX' privilege in addition to the privileges
     mentioned earlier.

     While the non-unique indexes are disabled, they are ignored for
     statements such as *Note `SELECT': select.  and *Note `EXPLAIN':
     explain. that otherwise would use them.

   * If *Note `ALTER TABLE': alter-table. for an `InnoDB' table results
     in changes to column values (for example, because a column is
     truncated), `InnoDB''s `FOREIGN KEY' constraint checks do not
     notice possible violations caused by changing the values.

   * The `FOREIGN KEY' and `REFERENCES' clauses are supported by the
     `InnoDB' storage engine, which implements `ADD [CONSTRAINT
     [SYMBOL]] FOREIGN KEY (...) REFERENCES ... (...)'. See *Note
     innodb-foreign-key-constraints::. For other storage engines, the
     clauses are parsed but ignored. The `CHECK' clause is parsed but
     ignored by all storage engines. See *Note create-table::. The
     reason for accepting but ignoring syntax clauses is for
     compatibility, to make it easier to port code from other SQL
     servers, and to run applications that create tables with
     references. See *Note differences-from-ansi::.

     *Important*:

     The inline `REFERENCES' specifications where the references are
     defined as part of the column specification are silently ignored by
     `InnoDB'. InnoDB only accepts `REFERENCES' clauses defined as part
     of a separate `FOREIGN KEY' specification.

     *Note*:

     Partitioned tables do not support foreign keys. See *Note
     partitioning-limitations::, for more information.

   * `InnoDB' supports the use of *Note `ALTER TABLE': alter-table. to
     drop foreign keys:

          ALTER TABLE TBL_NAME DROP FOREIGN KEY FK_SYMBOL;

     For more information, see *Note innodb-foreign-key-constraints::.

   * You cannot add a foreign key and drop a foreign key in separate
     clauses of a single *Note `ALTER TABLE': alter-table. statement.
     You must use separate statements.

   * For an `InnoDB' table that is created with its own tablespace in
     an `.ibd' file, that file can be discarded and imported. To
     discard the `.ibd' file, use this statement:

          ALTER TABLE TBL_NAME DISCARD TABLESPACE;

     This deletes the current `.ibd' file, so be sure that you have a
     backup first. Attempting to access the table while the tablespace
     file is discarded results in an error.

     To import the backup `.ibd' file back into the table, copy it into
     the database directory, and then issue this statement:

          ALTER TABLE TBL_NAME IMPORT TABLESPACE;

     See *Note multiple-tablespaces::.

   * Pending *Note `INSERT DELAYED': insert-delayed.  statements are
     lost if a table is write locked and *Note `ALTER TABLE':
     alter-table. is used to modify the table structure.

   * If you want to change the table default character set and all
     character columns (*Note `CHAR': char, *Note `VARCHAR': char,
     *Note `TEXT': blob.) to a new character set, use a statement like
     this:

          ALTER TABLE TBL_NAME CONVERT TO CHARACTER SET CHARSET_NAME;

     For a column that has a data type of *Note `VARCHAR': char. or one
     of the *Note `TEXT': blob. types, `CONVERT TO CHARACTER SET' will
     change the data type as necessary to ensure that the new column is
     long enough to store as many characters as the original column.
     For example, a *Note `TEXT': blob. column has two length bytes,
     which store the byte-length of values in the column, up to a
     maximum of 65,535. For a `latin1' *Note `TEXT': blob. column, each
     character requires a single byte, so the column can store up to
     65,535 characters. If the column is converted to `utf8', each
     character might require up to four bytes, for a maximum possible
     length of 4 x 65,535 = 262,140 bytes. That length will not fit in a
     *Note `TEXT': blob. column's length bytes, so MySQL will convert
     the data type to *Note `MEDIUMTEXT': blob, which is the smallest
     string type for which the length bytes can record a value of
     262,140. Similarly, a *Note `VARCHAR': char. column might be
     converted to *Note `MEDIUMTEXT': blob.

     To avoid data type changes of the type just described, do not use
     `CONVERT TO CHARACTER SET'. Instead, use `MODIFY' to change
     individual columns. For example:

          ALTER TABLE t MODIFY latin1_text_col TEXT CHARACTER SET utf8;
          ALTER TABLE t MODIFY latin1_varchar_col VARCHAR(M) CHARACTER SET utf8;

     If you specify `CONVERT TO CHARACTER SET binary', the *Note
     `CHAR': char, *Note `VARCHAR': char, and *Note `TEXT': blob.
     columns are converted to their corresponding binary string types
     (*Note `BINARY': binary-varbinary, *Note `VARBINARY':
     binary-varbinary, *Note `BLOB': blob.). This means that the
     columns no longer will have a character set and a subsequent
     `CONVERT TO' operation will not apply to them.

     If CHARSET_NAME is `DEFAULT', the database character set is used.

     *Warning*:

     The `CONVERT TO' operation converts column values between the
     character sets. This is _not_ what you want if you have a column
     in one character set (like `latin1') but the stored values
     actually use some other, incompatible character set (like `utf8').
     In this case, you have to do the following for each such column:

          ALTER TABLE t1 CHANGE c1 c1 BLOB;
          ALTER TABLE t1 CHANGE c1 c1 TEXT CHARACTER SET utf8;

     The reason this works is that there is no conversion when you
     convert to or from *Note `BLOB': blob.  columns.

     To change only the _default_ character set for a table, use this
     statement:

          ALTER TABLE TBL_NAME DEFAULT CHARACTER SET CHARSET_NAME;

     The word `DEFAULT' is optional. The default character set is the
     character set that is used if you do not specify the character set
     for columns that you add to a table later (for example, with
     `ALTER TABLE ... ADD column').

   * Partitioning-related clauses for *Note `ALTER TABLE': alter-table.
     can be used with partitioned tables for repartitioning, for
     adding, dropping, merging, and splitting partitions, and for
     performing partitioning maintenance.

     Simply using a PARTITION_OPTIONS clause with *Note `ALTER TABLE':
     alter-table. on a partitioned table repartitions the table
     according to the partitioning scheme defined by the
     PARTITION_OPTIONS. This clause always begins with `PARTITION BY',
     and follows the same syntax and other rules as apply to the
     PARTITION_OPTIONS clause for *Note `CREATE TABLE': create-table.
     (see *Note create-table::, for more detailed information), and can
     also be used to partition an existing table that is not already
     partitioned. For example, consider a (non-partitioned) table
     defined as shown here:

          CREATE TABLE t1 (
              id INT,
              year_col INT
          );

     This table can be partitioned by `HASH', using the `id' column as
     the partitioning key, into 8 partitions by means of this statement:

          ALTER TABLE t1
              PARTITION BY HASH(id)
              PARTITIONS 8;

     The table that results from using an `ALTER TABLE ...  PARTITION
     BY' statement must follow the same rules as one created using
     `CREATE TABLE ... PARTITION BY'. This includes the rules governing
     the relationship between any unique keys (including any primary
     key) that the table might have, and the column or columns used in
     the partitioning expression, as discussed in *Note
     partitioning-limitations-partitioning-keys-unique-keys::.  The
     `CREATE TABLE ... PARTITION BY' rules for specifying the number of
     partitions also apply to `ALTER TABLE ... PARTITION BY'.

     The PARTITION_DEFINITION clause for `ALTER TABLE ADD PARTITION'
     supports the same options as the clause of the same name for the
     *Note `CREATE TABLE': create-table. statement. (See *Note
     create-table::, for the syntax and description.) Suppose that you
     have the partitioned table created as shown here:

          CREATE TABLE t1 (
              id INT,
              year_col INT
          )
          PARTITION BY RANGE (year_col) (
              PARTITION p0 VALUES LESS THAN (1991),
              PARTITION p1 VALUES LESS THAN (1995),
              PARTITION p2 VALUES LESS THAN (1999)
          );

     You can add a new partition `p3' to this table for storing values
     less than `2002' as follows:

          ALTER TABLE t1 ADD PARTITION (PARTITION p3 VALUES LESS THAN (2002));

     `DROP PARTITION' can be used to drop one or more `RANGE' or `LIST'
     partitions. This statement cannot be used with `HASH' or `KEY'
     partitions; instead, use `COALESCE PARTITION' (see below). Any
     data that was stored in the dropped partitions named in the
     PARTITION_NAMES list is discarded. For example, given the table
     `t1' defined previously, you can drop the partitions named `p0' and
     `p1' as shown here:

          ALTER TABLE t1 DROP PARTITION p0, p1;

     `ADD PARTITION' and `DROP PARTITION' do not currently support `IF
     [NOT] EXISTS'. It is also not possible to rename a partition or a
     partitioned table. Instead, if you wish to rename a partition, you
     must drop and re-create the partition; if you wish to rename a
     partitioned table, you must instead drop all partitions, rename
     the table, and then add back the partitions that were dropped.

     `COALESCE PARTITION' can be used with a table that is partitioned
     by `HASH' or `KEY' to reduce the number of partitions by NUMBER.
     Suppose that you have created table `t2' using the following
     definition:

          CREATE TABLE t2 (
              name VARCHAR (30),
              started DATE
          )
          PARTITION BY HASH( YEAR(started) )
          PARTITIONS 6;

     You can reduce the number of partitions used by `t2' from 6 to 4
     using the following statement:

          ALTER TABLE t2 COALESCE PARTITION 2;

     The data contained in the last NUMBER partitions will be merged
     into the remaining partitions. In this case, partitions 4 and 5
     will be merged into the first 4 partitions (the partitions
     numbered 0, 1, 2, and 3).

     To change some but not all the partitions used by a partitioned
     table, you can use `REORGANIZE PARTITION'. This statement can be
     used in several ways:

        * To merge a set of partitions into a single partition. This
          can be done by naming several partitions in the
          PARTITION_NAMES list and supplying a single definition for
          PARTITION_DEFINITION.

        * To split an existing partition into several partitions.  You
          can accomplish this by naming a single partition for
          PARTITION_NAMES and providing multiple PARTITION_DEFINITIONS.

        * To change the ranges for a subset of partitions defined using
          `VALUES LESS THAN' or the value lists for a subset of
          partitions defined using `VALUES IN'.

     *Note*:

     For partitions that have not been explicitly named, MySQL
     automatically provides the default names `p0', `p1', `p2', and so
     on. The same is true with regard to subpartitions.

     For more detailed information about and examples of `ALTER TABLE
     ... REORGANIZE PARTITION' statements, see *Note
     partitioning-management::.

     *Important*:

     Only a single `PARTITION BY', `ADD PARTITION', `DROP PARTITION',
     `REORGANIZE PARTITION', or `COALESCE PARTITION' clause can be used
     in a given *Note `ALTER TABLE': alter-table.  statement.

   * Several additional options available for providing partition
     maintenance and repair functionality analogous to that implemented
     for non-partitioned tables by statements such as *Note `CHECK
     TABLE': check-table. and *Note `REPAIR TABLE': repair-table.
     (which are are also supported for partitioned tables, beginning
     with MySQL 6.0.6 -- see note at the end of this item). These
     include `ANALYZE PARTITION', `CHECK PARTITION', `OPTIMIZE
     PARTITION', `REBUILD PARTITION', and `REPAIR PARTITION'. Each of
     these options takes a PARTITION_NAMES clause consisting of one or
     more names of partitions, separated by commas. The partitions must
     already exist in the table to be altered. For more information and
     examples, see *Note partitioning-maintenance::.

     The `ANALYZE PARTITION', `CHECK PARTITION', `OPTIMIZE PARTITION',
     and `REPAIR PARTITION' options were disabled in MySQL 6.0.5, and
     re-enabled in MySQL 6.0.6. (Bug#20129
     (http://bugs.mysql.com/20129)) They are not supported for tables
     which are not partitioned; beginning with MySQL 6.0.8, they are
     disallowed for such tables.

     *Note*:

     Beginning with MySQL 6.0.6, you can use the statements *Note
     `ANALYZE TABLE': analyze-table, *Note `CHECK TABLE': check-table,
     *Note `OPTIMIZE TABLE': optimize-table, and *Note `REPAIR TABLE':
     repair-table. on partitioned tables. See *Note
     table-maintenance-sql::, for more information.

   * `REMOVE PARTITIONING' enables you to remove a table's partitioning
     without otherwise affecting the table or its data. This option can
     be combined with other *Note `ALTER TABLE': alter-table. options
     such as those used to add, drop, or rename drop columns or indexes.

   * Using the `ENGINE' option with *Note `ALTER TABLE': alter-table.
     changes the storage engine used by the table without affecting the
     partitioning.

With the *Note `mysql_info()': mysql-info. C API function, you can find
out how many rows were copied, and (when `IGNORE' is used) how many
rows were deleted due to duplication of unique key values. See *Note
mysql-info::.

Here are some examples that show uses of *Note `ALTER TABLE':
alter-table. Begin with a table `t1' that is created as shown here:

     CREATE TABLE t1 (a INTEGER,b CHAR(10));

To rename the table from `t1' to `t2':

     ALTER TABLE t1 RENAME t2;

To change column `a' from *Note `INTEGER': numeric-types. to `TINYINT
NOT NULL' (leaving the name the same), and to change column `b' from
`CHAR(10)' to `CHAR(20)' as well as renaming it from `b' to `c':

     ALTER TABLE t2 MODIFY a TINYINT NOT NULL, CHANGE b c CHAR(20);

To add a new *Note `TIMESTAMP': datetime. column named `d':

     ALTER TABLE t2 ADD d TIMESTAMP;

To add an index on column `d' and a `UNIQUE' index on column `a':

     ALTER TABLE t2 ADD INDEX (d), ADD UNIQUE (a);

To remove column `c':

     ALTER TABLE t2 DROP COLUMN c;

To add a new `AUTO_INCREMENT' integer column named `c':

     ALTER TABLE t2 ADD c INT UNSIGNED NOT NULL AUTO_INCREMENT,
       ADD PRIMARY KEY (c);

Note that we indexed `c' (as a `PRIMARY KEY') because `AUTO_INCREMENT'
columns must be indexed, and also that we declare `c' as `NOT NULL'
because primary key columns cannot be `NULL'.

When you add an `AUTO_INCREMENT' column, column values are filled in
with sequence numbers automatically. For `MyISAM' tables, you can set
the first sequence number by executing `SET INSERT_ID=VALUE' before
*Note `ALTER TABLE': alter-table. or by using the `AUTO_INCREMENT=VALUE'
table option. See *Note server-session-variables::.

With `MyISAM' tables, if you do not change the `AUTO_INCREMENT' column,
the sequence number is not affected. If you drop an `AUTO_INCREMENT'
column and then add another `AUTO_INCREMENT' column, the numbers are
resequenced beginning with 1.

When replication is used, adding an `AUTO_INCREMENT' column to a table
might not produce the same ordering of the rows on the slave and the
master.  This occurs because the order in which the rows are numbered
depends on the specific storage engine used for the table and the order
in which the rows were inserted. If it is important to have the same
order on the master and slave, the rows must be ordered before
assigning an `AUTO_INCREMENT' number.  Assuming that you want to add an
`AUTO_INCREMENT' column to the table `t1', the following statements
produce a new table `t2' identical to `t1' but with an `AUTO_INCREMENT'
column:

     CREATE TABLE t2 (id INT AUTO_INCREMENT PRIMARY KEY)
     SELECT * FROM t1 ORDER BY col1, col2;

This assumes that the table `t1' has columns `col1' and `col2'.

This set of statements will also produce a new table `t2' identical to
`t1', with the addition of an `AUTO_INCREMENT' column:

     CREATE TABLE t2 LIKE t1;
     ALTER TABLE T2 ADD id INT AUTO_INCREMENT PRIMARY KEY;
     INSERT INTO t2 SELECT * FROM t1 ORDER BY col1, col2;

*Important*:

To guarantee the same ordering on both master and slave, _all_ columns
of `t1' must be referenced in the `ORDER BY' clause.

Regardless of the method used to create and populate the copy having
the `AUTO_INCREMENT' column, the final step is to drop the original
table and then rename the copy:

     DROP t1;
     ALTER TABLE t2 RENAME t1;


File: manual.info,  Node: alter-view,  Next: create-database,  Prev: alter-table,  Up: sql-syntax-data-definition

12.1.7 `ALTER VIEW' Syntax
--------------------------

     ALTER
         [ALGORITHM = {UNDEFINED | MERGE | TEMPTABLE}]
         [DEFINER = { USER | CURRENT_USER }]
         [SQL SECURITY { DEFINER | INVOKER }]
         VIEW VIEW_NAME [(COLUMN_LIST)]
         AS SELECT_STATEMENT
         [WITH [CASCADED | LOCAL] CHECK OPTION]

This statement changes the definition of a view, which must exist.  The
syntax is similar to that for *Note `CREATE VIEW': create-view. and the
effect is the same as for `CREATE OR REPLACE VIEW'. See *Note
create-view::. This statement requires the `CREATE VIEW' and `DROP'
privileges for the view, and some privilege for each column referred to
in the *Note `SELECT': select. statement. As of MySQL 6.0.4, *Note
`ALTER VIEW': alter-view. is allowed only to the definer or users with
the `SUPER' privilege.


File: manual.info,  Node: create-database,  Next: create-event,  Prev: alter-view,  Up: sql-syntax-data-definition

12.1.8 `CREATE DATABASE' Syntax
-------------------------------

     CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] DB_NAME
         [CREATE_SPECIFICATION] ...

     CREATE_SPECIFICATION:
         [DEFAULT] CHARACTER SET [=] CHARSET_NAME
       | [DEFAULT] COLLATE [=] COLLATION_NAME

*Note `CREATE DATABASE': create-database. creates a database with the
given name. To use this statement, you need the `CREATE' privilege for
the database.  *Note `CREATE SCHEMA': create-database. is a synonym for
*Note `CREATE DATABASE': create-database.

An error occurs if the database exists and you did not specify `IF NOT
EXISTS'.

CREATE_SPECIFICATION options specify database characteristics. Database
characteristics are stored in the `db.opt' file in the database
directory.  The `CHARACTER SET' clause specifies the default database
character set. The `COLLATE' clause specifies the default database
collation.  *Note charset::, discusses character set and collation
names.

A database in MySQL is implemented as a directory containing files that
correspond to tables in the database. Because there are no tables in a
database when it is initially created, the *Note `CREATE DATABASE':
create-database. statement creates only a directory under the MySQL
data directory and the `db.opt' file. Rules for allowable database
names are given in *Note identifiers::. If a database name contains
special characters, the name for the database directory contains
encoded versions of those characters as described in *Note
identifier-mapping::.

If you manually create a directory under the data directory (for
example, with `mkdir'), the server considers it a database directory
and it shows up in the output of *Note `SHOW DATABASES': show-databases.

You can also use the *Note `mysqladmin': mysqladmin. program to create
databases. See *Note mysqladmin::.


File: manual.info,  Node: create-event,  Next: create-function,  Prev: create-database,  Up: sql-syntax-data-definition

12.1.9 `CREATE EVENT' Syntax
----------------------------

     CREATE
         [DEFINER = { USER | CURRENT_USER }]
         EVENT
         [IF NOT EXISTS]
         EVENT_NAME
         ON SCHEDULE SCHEDULE
         [ON COMPLETION [NOT] PRESERVE]
         [ENABLE | DISABLE | DISABLE ON SLAVE]
         [COMMENT 'COMMENT']
         DO SQL_STATEMENT;

     SCHEDULE:
         AT TIMESTAMP [+ INTERVAL INTERVAL] ...
       | EVERY INTERVAL
         [STARTS TIMESTAMP [+ INTERVAL interval] ...]
         [ENDS TIMESTAMP [+ INTERVAL interval] ...]

     INTERVAL:
         QUANTITY {YEAR | QUARTER | MONTH | DAY | HOUR | MINUTE |
                   WEEK | SECOND | YEAR_MONTH | DAY_HOUR | DAY_MINUTE |
                   DAY_SECOND | HOUR_MINUTE | HOUR_SECOND | MINUTE_SECOND}

This statement creates and schedules a new event. It requires the
`EVENT' privilege for the schema in which the event is to be created.

The minimum requirements for a valid *Note `CREATE EVENT':
create-event. statement are as follows:

   * The keywords *Note `CREATE EVENT': create-event. plus an event
     name, which uniquely identifies the event in the current schema.

   * An `ON SCHEDULE' clause, which determines when and how often the
     event executes.

   * A *Note `DO': do. clause, which contains the SQL statement to be
     executed by an event.

This is an example of a minimal *Note `CREATE EVENT': create-event.
statement:

     CREATE EVENT myevent
         ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 1 HOUR
         DO
           UPDATE myschema.mytable SET mycol = mycol + 1;

The previous statement creates an event named `myevent'. This event
executes once -- one hour following its creation -- by running an SQL
statement that increments the value of the `myschema.mytable' table's
`mycol' column by 1.

The EVENT_NAME must be a valid MySQL identifier with a maximum length
of 64 characters. It may be delimited using back ticks, and may be
qualified with the name of a database schema. An event is associated
with both a MySQL user (the definer) and a schema, and its name must be
unique among names of events within that schema. In general, the rules
governing event names are the same as those for names of stored
routines. See *Note identifiers::.

If no schema is indicated as part of EVENT_NAME, the default (current)
schema is assumed.

*Note*:

MySQL uses case-insensitive comparisons when checking for the
uniqueness of event names. This means that, for example, you cannot
have two events named `myevent' and `MyEvent' in the same database
schema.

The `DEFINER' clause specifies the MySQL account to be used when
checking access privileges at event execution time. If a USER value is
given, it should be a MySQL account in `'USER_NAME'@'HOST_NAME'' format
(the same format used in the *Note `GRANT': grant. statement). The
USER_NAME and HOST_NAME values both are required.  `CURRENT_USER' also
can be given as `CURRENT_USER()'. The default `DEFINER' value is the
user who executes the *Note `CREATE EVENT': create-event. statement.
(This is the same as `DEFINER = CURRENT_USER'.)

If you specify the `DEFINER' clause, these rules determine the legal
`DEFINER' user values:

   * If you do not have the `SUPER' privilege, the only legal USER
     value is your own account, either specified literally or by using
     `CURRENT_USER'. You cannot set the definer to some other account.

   * If you have the `SUPER' privilege, you can specify any
     syntactically legal account name. If the account does not actually
     exist, a warning is generated.

   * Although it is possible to create routines with a non-existent
     `DEFINER' value, an error occurs if the routine executes with
     definer privileges but the definer does not exist at execution
     time.

Within an event, the `CURRENT_USER()' function returns the account used
to check privileges at event execution time, which is the `DEFINER'
user. For information about user auditing within events, see *Note
account-activity-auditing::.

`IF NOT EXISTS' has the same meaning for *Note `CREATE EVENT':
create-event. as for *Note `CREATE TABLE': create-table.: If an event
named EVENT_NAME already exists in the same schema, no action is taken,
and no error results. (However, a warning is generated in such cases.)

The `ON SCHEDULE' clause determines when, how often, and for how long
the SQL_STATEMENT defined for the event repeats. This clause takes one
of two forms:

   * `AT TIMESTAMP' is used for a one-time event. It specifies that the
     event executes one time only at the date and time given by
     TIMESTAMP, which must include both the date and time, or must be
     an expression that resolves to a datetime value. You may use a
     value of either the *Note `DATETIME': datetime. or *Note
     `TIMESTAMP': datetime. type for this purpose. If the date is in
     the past, a warning occurs, as shown here:

          mysql> SELECT NOW();
          +---------------------+
          | NOW()               |
          +---------------------+
          | 2006-02-10 23:59:01 |
          +---------------------+
          1 row in set (0.04 sec)

          mysql> CREATE EVENT e_totals
              ->     ON SCHEDULE AT '2006-02-10 23:59:00'
              ->     DO INSERT INTO test.totals VALUES (NOW());
          Query OK, 0 rows affected, 1 warning (0.00 sec)

          mysql> SHOW WARNINGS\G
          *************************** 1. row ***************************
            Level: Note
             Code: 1588
          Message: Event execution time is in the past and ON COMPLETION NOT
                   PRESERVE is set. The event was dropped immediately after
                   creation.

     *Note `CREATE EVENT': create-event. statements which are
     themselves invalid -- for whatever reason -- fail with an error.

     You may use `CURRENT_TIMESTAMP' to specify the current date and
     time. In such a case, the event acts as soon as it is created.

     To create an event which occurs at some point in the future
     relative to the current date and time -- such as that expressed by
     the phrase `three weeks from now' -- you can use the optional
     clause `+ INTERVAL INTERVAL'. The INTERVAL portion consists of two
     parts, a quantity and a unit of time, and follows the same syntax
     rules that govern intervals used in the `DATE_ADD()' function (see
     *Note date-and-time-functions::. The units keywords are also the
     same, except that you cannot use any units involving microseconds
     when defining an event. With some interval types, complex time
     units may be used. For example, `two minutes and ten seconds' can
     be expressed as `+ INTERVAL '2:10' MINUTE_SECOND'.

     You can also combine intervals. For example, `AT CURRENT_TIMESTAMP
     + INTERVAL 3 WEEK + INTERVAL 2 DAY' is equivalent to `three weeks
     and two days from now'. Each portion of such a clause must begin
     with `+ INTERVAL'.

   * To repeat actions at a regular interval, use an `EVERY' clause.
     The `EVERY' keyword is followed by an INTERVAL as described in the
     previous dicussion of the `AT' keyword. (`+ INTERVAL' is _not_
     used with `EVERY'.) For example, `EVERY 6 WEEK' means `every six
     weeks'.

     Although `+ INTERVAL' clauses are not allowed in an `EVERY'
     clause, you can use the same complex time units allowed in a `+
     INTERVAL'.

     An `EVERY' clause may also contain an optional `STARTS' clause.
     `STARTS' is followed by a TIMESTAMP value which indicates when the
     action should begin repeating, and may also use `+ INTERVAL
     INTERVAL' in order to specify an amount of time `from now'. For
     example, `EVERY 3 MONTH STARTS CURRENT_TIMESTAMP + INTERVAL 1
     WEEK' means `every three months, beginning one week from now'.
     Similarly, you can express `every two weeks, beginning six hours
     and fifteen minutes from now' as `EVERY 2 WEEK STARTS
     CURRENT_TIMESTAMP + INTERVAL '6:15' HOUR_MINUTE'. Not specifying
     `STARTS' is the same as using `STARTS CURRENT_TIMESTAMP' -- that
     is, the action specified for the event begins repeating
     immediately upon creation of the event.

     An `EVERY' clause may also contain an optional `ENDS' clause. The
     `ENDS' keyword is followed by a TIMESTAMP value which tells MySQL
     when the event should stop repeating. You may also use `+ INTERVAL
     INTERVAL' with `ENDS'; for instance, `EVERY 12 HOUR STARTS
     CURRENT_TIMESTAMP + INTERVAL 30 MINUTE ENDS CURRENT_TIMESTAMP +
     INTERVAL 4 WEEK' is equivalent to `every twelve hours, beginning
     thirty minutes from now, and ending four weeks from now'. Not using
     `ENDS' means that the event continues executing indefinitely.

     `ENDS' supports the same syntax for complex time units as `STARTS'
     does.

     You may use `STARTS', `ENDS', both, or neither in an `EVERY'
     clause.

     *Note*:

     In MySQL 6.0, `STARTS' or `ENDS' uses the MySQL server's local time
     zone, as shown in the *Note `INFORMATION_SCHEMA.EVENTS':
     events-table. and `mysql.event' tables, as well as in the output
     of *Note `SHOW EVENTS': show-events.

     See *Note events-table::, and *Note show-events:: for more
     information.

     If a repeating event does not terminate within its scheduling
     interval, the result may be multiple instances of the event
     executing simultaneously. If this is undesirable, you should
     institute a mechanism to prevent simultaneous instances. For
     example, you could use the `GET_LOCK()' function, or row or table
     locking.

The `ON SCHEDULE' clause may use expressions involving built-in MySQL
functions and user variables to obtain any of the TIMESTAMP or INTERVAL
values which it contains. You may not use stored functions or
user-defined functions in such expressions, nor may you use any table
references; however, you may use `SELECT FROM DUAL'. This is true for
both *Note `CREATE EVENT': create-event. and *Note `ALTER EVENT':
alter-event. statements. References to stored functions, user-defined
functions, and tables in such cases are specifically disallowed, and
fail with an error (see Bug#22830 (http://bugs.mysql.com/22830)).

Normally, once an event has expired, it is immediately dropped.  You
can override this behavior by specifying `ON COMPLETION PRESERVE'.
Using `ON COMPLETION NOT PRESERVE' merely makes the default
non-persistent behavior explicit.

You can create an event but keep it from being active using the
`DISABLE' keyword. Alternatively, you may use `ENABLE' to make explicit
the default status, which is active. This is most useful in conjunction
with *Note `ALTER EVENT': alter-event. (see *Note alter-event::).

A third value may also appear in place of `ENABLED' or `DISABLED';
`DISABLE ON SLAVE' is set for the status of an event on a replication
slave to indicate that the event was created on the master and
replicated to the slave, but is not executed on the slave. See *Note
replication-features-invoked::.

You may supply a comment for an event using a `COMMENT' clause.
COMMENT may be any string of up to 64 characters that you wish to use
for describing the event. The comment text, being a string literal,
must be surrounded by quotation marks.

The *Note `DO': do. clause specifies an action carried by the event,
and consists of an SQL statement. Nearly any valid MySQL statement
which can be used in a stored routine can also be used as the action
statement for a scheduled event. (See *Note
stored-program-restrictions::.) For example, the following event
`e_hourly' deletes all rows from the `sessions' table once per hour,
where this table is part of the `site_activity' schema:

     CREATE EVENT e_hourly
         ON SCHEDULE
           EVERY 1 HOUR
         COMMENT 'Clears out sessions table each hour.'
         DO
           DELETE FROM site_activity.sessions;

MySQL stores the `sql_mode' system variable setting that is in effect
at the time an event is created, and always executes the event with
this setting in force, _regardless of the current server SQL mode_.

A *Note `CREATE EVENT': create-event. statement that contains an *Note
`ALTER EVENT': alter-event. statement in its *Note `DO': do. clause
appears to succeed; however, when the server attempts to execute the
resulting scheduled event, the execution fails with an error.

*Note*:

Statements such as *Note `SELECT': select. or *Note `SHOW': show. that
merely return a result set have no effect when used in an event; the
output from these is not sent to the MySQL Monitor, nor is it stored
anywhere.  However, you can use statements such as `SELECT ...  INTO'
and `INSERT INTO ... SELECT' that store a result. (See the next example
in this section for an instance of the latter.)

The schema to which an event belongs is the default schema for table
references in the *Note `DO': do. clause.  Any references to tables in
other schemas must be qualified with the proper schema name.

As with stored routines, you can use compound-statement syntax in the
*Note `DO': do. clause by using the `BEGIN' and `END' keywords, as
shown here:

     delimiter |

     CREATE EVENT e_daily
         ON SCHEDULE
           EVERY 1 DAY
         COMMENT 'Saves total number of sessions then clears the table each day'
         DO
           BEGIN
             INSERT INTO site_activity.totals (time, total)
               SELECT CURRENT_TIMESTAMP, COUNT(*)
                 FROM site_activity.sessions;
             DELETE FROM site_activity.sessions;
           END |

     delimiter ;

Note the use of the `delimiter' command to change the statement
delimiter. See *Note stored-programs-defining::.

More complex compound statements, such as those used in stored
routines, are possible in an event. This example uses local variables,
an error handler, and a flow control construct:

     delimiter |

     CREATE EVENT e
         ON SCHEDULE
           EVERY 5 SECOND
         DO
           BEGIN
             DECLARE v INTEGER;
             DECLARE CONTINUE HANDLER FOR SQLEXCEPTION BEGIN END;

             SET v = 0;

             WHILE v < 5 DO
               INSERT INTO t1 VALUES (0);
               UPDATE t2 SET s1 = s1 + 1;
               SET v = v + 1;
             END WHILE;
         END |

     delimiter ;

There is no way to pass parameters directly to or from events; however,
it is possible to invoke a stored routine with parameters:

     CREATE EVENT e_call_myproc
         ON SCHEDULE
           AT CURRENT_TIMESTAMP + INTERVAL 1 DAY
         DO CALL myproc(5, 27);

In addition, if the event's definer has the `SUPER' privilege, that
event may read and write global variables. As granting this privilege
entails a potential for abuse, extreme care must be taken in doing so.

Generally, any statements which are valid in stored routines may be
used for action statements executed by events. For more information
about statements allowable within stored routines, see *Note
stored-routines-syntax::. You can create an event as part of a stored
routine, but an event cannot be created by another event.


File: manual.info,  Node: create-function,  Next: create-index,  Prev: create-event,  Up: sql-syntax-data-definition

12.1.10 `CREATE FUNCTION' Syntax
--------------------------------

The *Note `CREATE FUNCTION': create-function. statement is used to
create stored functions and user-defined functions (UDFs):

   * For information about creating stored functions, see *Note
     create-procedure::.

   * For information about creating user-defined functions, see *Note
     create-function-udf::.


File: manual.info,  Node: create-index,  Next: create-procedure,  Prev: create-function,  Up: sql-syntax-data-definition

12.1.11 `CREATE INDEX' Syntax
-----------------------------

     CREATE [UNIQUE|FULLTEXT|SPATIAL] INDEX INDEX_NAME
         [INDEX_TYPE]
         ON TBL_NAME (INDEX_COL_NAME,...)
         [INDEX_OPTION] ...

     INDEX_COL_NAME:
         COL_NAME [(LENGTH)] [ASC | DESC]

     INDEX_TYPE:
         USING {BTREE | HASH | RTREE}

     INDEX_OPTION:
         KEY_BLOCK_SIZE [=] VALUE
       | INDEX_TYPE
       | WITH PARSER PARSER_NAME
       | COMMENT 'STRING'

*Note `CREATE INDEX': create-index. is mapped to an *Note `ALTER
TABLE': alter-table. statement to create indexes. See *Note
alter-table::.  *Note `CREATE INDEX': create-index. cannot be used to
create a `PRIMARY KEY'; use *Note `ALTER TABLE': alter-table. instead.
For more information about indexes, see *Note mysql-indexes::.

Normally, you create all indexes on a table at the time the table
itself is created with *Note `CREATE TABLE': create-table. See *Note
create-table::.  *Note `CREATE INDEX': create-index. enables you to add
indexes to existing tables.

A column list of the form `(col1,col2,...)' creates a multiple-column
index. Index values are formed by concatenating the values of the given
columns.

Indexes can be created that use only the leading part of column values,
using `COL_NAME(LENGTH)' syntax to specify an index prefix length:

   * Prefixes can be specified for *Note `CHAR': char, *Note `VARCHAR':
     char, *Note `BINARY': binary-varbinary, and *Note `VARBINARY':
     binary-varbinary. columns.

   * *Note `BLOB': blob. and *Note `TEXT': blob. columns also can be
     indexed, but a prefix length _must_ be given.

   * Prefix lengths are given in characters for non-binary string types
     and in bytes for binary string types. That is, index entries
     consist of the first LENGTH characters of each column value for
     *Note `CHAR': char, *Note `VARCHAR': char, and *Note `TEXT': blob.
     columns, and the first LENGTH bytes of each column value for *Note
     `BINARY': binary-varbinary, *Note `VARBINARY': binary-varbinary,
     and *Note `BLOB': blob. columns.

   * For spatial columns, prefix values cannot be given, as described
     later in this section.

The statement shown here creates an index using the first 10 characters
of the `name' column:

     CREATE INDEX part_of_name ON customer (name(10));

If names in the column usually differ in the first 10 characters, this
index should not be much slower than an index created from the entire
`name' column. Also, using column prefixes for indexes can make the
index file much smaller, which could save a lot of disk space and might
also speed up *Note `INSERT': insert. operations.

Prefix lengths are storage engine-dependent (for example, a prefix can
be up to 1000 bytes long for `MyISAM' tables, 767 bytes for `InnoDB'
tables). Note that prefix limits are measured in bytes, whereas the
prefix length in *Note `CREATE INDEX': create-index. statements is
interpreted as number of characters for non-binary data types (*Note
`CHAR': char, *Note `VARCHAR': char, *Note `TEXT': blob.). Take this
into account when specifying a prefix length for a column that uses a
multi-byte character set. For example, `utf8' columns require up to
four index bytes per character.

Indexes on variable-width columns are created online; that is, creating
the indexes does not require any copying. This is done automatically by
the server whenever it determines that it is possible to do so; you do
not have to use any special SQL syntax or server options to cause it to
happen.

In standard MySQL 6.0 releases, it is not possible to override the
server when it determines that an index is to be created online. For
more information, see *Note alter-table::.

A `UNIQUE' index creates a constraint such that all values in the index
must be distinct. An error occurs if you try to add a new row with a
key value that matches an existing row. For all engines, a `UNIQUE'
index allows multiple `NULL' values for columns that can contain
`NULL'. If you specify a prefix value for a column in a `UNIQUE' index,
the column values must be unique within the prefix.

MySQL Enterprise

Lack of proper indexes can greatly reduce performance. Subscribe to the
MySQL Enterprise Monitor for notification of inefficient use of
indexes. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

`FULLTEXT' indexes are supported only for `MyISAM' tables and can
include only *Note `CHAR': char, *Note `VARCHAR': char, and *Note
`TEXT': blob. columns. Indexing always happens over the entire column;
column prefix indexing is not supported and any prefix length is
ignored if specified. See *Note fulltext-search::, for details of
operation.

The `MyISAM', `InnoDB', `NDB', `BDB', and `ARCHIVE' storage engines
support spatial columns such as (`POINT' and `GEOMETRY'.  (*Note
spatial-extensions::, describes the spatial data types.) However,
support for spatial column indexing varies among engines. Spatial and
non-spatial indexes are available according to the following rules.

Spatial indexes (created using `SPATIAL INDEX'):

   * Available only for `MyISAM' tables.  Specifying a `SPATIAL INDEX'
     for other storage engines results in an error.

   * Indexed columns must be `NOT NULL'.

   * In MySQL 6.0, column prefix lengths are prohibited. The full width
     of each column is indexed.

Non-spatial indexes (created with `INDEX', `UNIQUE', or `PRIMARY KEY'):

   * Allowed for any storage engine that supports spatial columns
     except `ARCHIVE'.

   * Columns can be `NULL' unless the index is a primary key.

   * For each spatial column in a non-`SPATIAL' index except `POINT'
     columns, a column prefix length must be specified. (This is the
     same requirement as for indexed *Note `BLOB': blob. columns.) The
     prefix length is given in bytes.

   * The index type for a non-`SPATIAL' index depends on the storage
     engine. Currently, B-tree is used.

In MySQL 6.0:

   * You can add an index on a column that can have `NULL' values only
     if you are using the `MyISAM', `InnoDB', or `MEMORY' storage
     engine.

   * You can add an index on a *Note `BLOB': blob.  or *Note `TEXT':
     blob. column only if you are using the `MyISAM', or `InnoDB'
     storage engine.

An INDEX_COL_NAME specification can end with `ASC' or `DESC'. These
keywords are allowed for future extensions for specifying ascending or
descending index value storage. Currently, they are parsed but ignored;
index values are always stored in ascending order.

Following the index column list, index options can be given. An
INDEX_OPTION value can be any of the following:

   * `KEY_BLOCK_SIZE [=] VALUE'

     This option provides a hint to the storage engine about the size
     in bytes to use for index key blocks. The engine is allowed to
     change the value if necessary. A value of 0 indicates that the
     default value should be used.

   * INDEX_TYPE

     Some storage engines allow you to specify an index type when
     creating an index. The allowable index type values supported by
     different storage engines are shown in the following table.  Where
     multiple index types are listed, the first one is the default when
     no index type specifier is given.

     *Storage      *Allowable Index Types*
     Engine*       
     `MyISAM'      `BTREE', `RTREE'
     `InnoDB'      `BTREE'
     `MEMORY'/`HEAP'`HASH', `BTREE'
     `NDB'         `HASH', `BTREE' (see note in text)

     The `RTREE' index type is allowable only for `SPATIAL' indexes.

     If you specify an index type that is not legal for a given storage
     engine, but there is another index type available that the engine
     can use without affecting query results, the engine uses the
     available type.

     Examples:

          CREATE TABLE lookup (id INT) ENGINE = MEMORY;
          CREATE INDEX id_index USING BTREE ON lookup (id);

     `TYPE TYPE_NAME' is recognized as a synonym for `USING TYPE_NAME'.
     However, `USING' is the preferred form.

     The INDEX_TYPE option can also be given before the `ON TBL_NAME'
     clause. Use of the option in this position is deprecated; support
     for it is to be dropped in a future MySQL release. If an
     `index_type' option is given in both the earlier and later
     positions, the final option applies.

   * `WITH PARSER PARSER_NAME'

     This option can be used only with `FULLTEXT' indexes. It
     associates a parser plugin with the index if full-text indexing
     and searching operations need special handling. See *Note
     plugin-api::, for details on creating plugins.

   * Index definitions can include an optional comment of up to 1024
     characters.


File: manual.info,  Node: create-procedure,  Next: create-server,  Prev: create-index,  Up: sql-syntax-data-definition

12.1.12 `CREATE PROCEDURE' and `CREATE FUNCTION' Syntax
-------------------------------------------------------

     CREATE
         [DEFINER = { USER | CURRENT_USER }]
         PROCEDURE SP_NAME ([PROC_PARAMETER[,...]])
         [CHARACTERISTIC ...] ROUTINE_BODY

     CREATE
         [DEFINER = { USER | CURRENT_USER }]
         FUNCTION SP_NAME ([FUNC_PARAMETER[,...]])
         RETURNS TYPE
         [CHARACTERISTIC ...] ROUTINE_BODY

     PROC_PARAMETER:
         [ IN | OUT | INOUT ] PARAM_NAME TYPE

     FUNC_PARAMETER:
         PARAM_NAME TYPE

     TYPE:
         ANY VALID MYSQL DATA TYPE

     CHARACTERISTIC:
         LANGUAGE SQL
       | [NOT] DETERMINISTIC
       | { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA }
       | SQL SECURITY { DEFINER | INVOKER }
       | COMMENT 'STRING'

     ROUTINE_BODY:
         VALID SQL PROCEDURE STATEMENT

These statements create stored routines. By default, a routine is
associated with the default database. To associate the routine
explicitly with a given database, specify the name as DB_NAME.SP_NAME
when you create it.

The *Note `CREATE FUNCTION': create-function. statement is also used in
MySQL to support UDFs (user-defined functions). See *Note
adding-functions::. A UDF can be regarded as an external stored
function. However, do note that stored functions share their namespace
with UDFs. See *Note function-resolution::, for the rules describing
how the server interprets references to different kinds of functions.

When the routine is invoked, an implicit `USE DB_NAME' is performed (and
undone when the routine terminates). The causes the routine to have the
given default database while it executes.  *Note `USE': use. statements
within stored routines are disallowed.

When a stored function has been created, you invoke it by referring to
it in an expression. The function returns a value during expression
evaluation. When a stored procedure has been created, you invoke it by
using the *Note `CALL': call. statement (see *Note call::).

To execute the *Note `CREATE PROCEDURE': create-procedure. or *Note
`CREATE FUNCTION': create-function. statement, it is necessary to have
the `CREATE ROUTINE' privilege. By default, MySQL automatically grants
the `ALTER ROUTINE' and `EXECUTE' privileges to the routine creator.
See also *Note stored-routines-privileges::. If binary logging is
enabled, the *Note `CREATE FUNCTION': create-function. statement might
also require the `SUPER' privilege, as described in *Note
stored-programs-logging::.

The `DEFINER' and `SQL SECURITY' clauses specify the security context
to be used when checking access privileges at routine execution time,
as described later.

If the routine name is the same as the name of a built-in SQL function,
you must use a space between the name and the following parenthesis
when defining the routine, or a syntax error occurs.  This is also true
when you invoke the routine later. For this reason, we suggest that it
is better to avoid re-using the names of existing SQL functions for
your own stored routines.

The `IGNORE_SPACE' SQL mode applies to built-in functions, not to
stored routines. It is always allowable to have spaces after a routine
name, regardless of whether `IGNORE_SPACE' is enabled.

The parameter list enclosed within parentheses must always be present.
If there are no parameters, an empty parameter list of `()' should be
used. Parameter names are not case sensitive.

Each parameter can be declared to use any valid data type, except that
the `COLLATE' attribute cannot be used.

Each parameter is an `IN' parameter by default.  To specify otherwise
for a parameter, use the keyword `OUT' or `INOUT' before the parameter
name.

*Note*:

Specifying a parameter as `IN', `OUT', or `INOUT' is valid only for a
`PROCEDURE'.  (`FUNCTION' parameters are always regarded as `IN'
parameters.)

An `IN' parameter passes a value into a procedure. The procedure might
modify the value, but the modification is not visible to the caller
when the procedure returns. An `OUT' parameter passes a value from the
procedure back to the caller. Its initial value is `NULL' within the
procedure, and its value is visible to the caller when the procedure
returns. An `INOUT' parameter is initialized by the caller, can be
modified by the procedure, and any change made by the procedure is
visible to the caller when the procedure returns.

For each `OUT' or `INOUT' parameter, pass a user-defined variable in the
*Note `CALL': call. statement that invokes the procedure so that you
can obtain its value when the procedure returns. If you are calling the
procedure from within another stored procedure or function, you can
also pass a routine parameter or local routine variable as an `IN' or
`INOUT' parameter.

The `RETURNS' clause may be specified only for a `FUNCTION', for which
it is mandatory. It indicates the return type of the function, and the
function body must contain a `RETURN VALUE' statement. If the *Note
`RETURN': return. statement returns a value of a different type, the
value is coerced to the proper type. For example, if a function
specifies an *Note `ENUM': enum. or *Note `SET': set. value in the
`RETURNS' clause, but the *Note `RETURN': return. statement returns an
integer, the value returned from the function is the string for the
corresponding *Note `ENUM': enum. member of set of *Note `SET': set.
members.

The ROUTINE_BODY consists of a valid SQL procedure statement. This can
be a simple statement such as *Note `SELECT': select. or *Note
`INSERT': insert, or it can be a compound statement written using
`BEGIN' and `END'. Compound statements can contain declarations, loops,
and other control structure statements. The syntax for these statements
is described in *Note sql-syntax-compound-statements::.

MySQL allows routines to contain DDL statements, such as `CREATE' and
`DROP'. MySQL also allows stored procedures (but not stored functions)
to contain SQL transaction statements such as *Note `COMMIT': commit.
Stored functions may not contain statements that perform explicit or
implicit commit or rollback. Support for these statements is not
required by the SQL standard, which states that each DBMS vendor may
decide whether to allow them.

Statements that return a result set cannot be used within a stored
function. This includes *Note `SELECT': select.  statements that do not
have an `INTO VAR_LIST' clause and other statements such as *Note
`SHOW': show, *Note `EXPLAIN': explain, and *Note `CHECK TABLE':
check-table. For statements that can be determined at function
definition time to return a result set, a `Not allowed to return a
result set from a function' error occurs (`ER_SP_NO_RETSET'). For
statements that can be determined only at runtime to return a result
set, a `PROCEDURE %s can't return a result set in the given context'
error occurs (`ER_SP_BADSELECT').

For additional information about statements that are not allowed in
stored routines, see *Note stored-program-restrictions::.

The following example shows a simple stored procedure that uses an
`OUT' parameter:

     mysql> delimiter //

     mysql> CREATE PROCEDURE simpleproc (OUT param1 INT)
         -> BEGIN
         ->   SELECT COUNT(*) INTO param1 FROM t;
         -> END;
         -> //
     Query OK, 0 rows affected (0.00 sec)

     mysql> delimiter ;

     mysql> CALL simpleproc(@a);
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @a;
     +------+
     | @a   |
     +------+
     | 3    |
     +------+
     1 row in set (0.00 sec)

The example uses the *Note `mysql': mysql. client `delimiter' command
to change the statement delimiter from `;' to `//' while the procedure
is being defined. This allows the `;' delimiter used in the procedure
body to be passed through to the server rather than being interpreted by
*Note `mysql': mysql. itself. See *Note stored-programs-defining::.

For information about invoking stored procedures from within programs
written in a language that has a MySQL interface, see *Note call::.

The following example function takes a parameter, performs an operation
using an SQL function, and returns the result. In this case, it is
unnecessary to use `delimiter' because the function definition contains
no internal `;' statement delimiters:

     mysql> CREATE FUNCTION hello (s CHAR(20))
     mysql> RETURNS CHAR(50) DETERMINISTIC
         -> RETURN CONCAT('Hello, ',s,'!');
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT hello('world');
     +----------------+
     | hello('world') |
     +----------------+
     | Hello, world!  |
     +----------------+
     1 row in set (0.00 sec)

MySQL stores the `sql_mode' system variable setting that is in effect
at the time a routine is created, and always executes the routine with
this setting in force, _regardless of the server SQL mode in effect when
the routine is invoked_.

A procedure or function is considered `deterministic' if it always
produces the same result for the same input parameters, and `not
deterministic' otherwise. If neither `DETERMINISTIC' nor `NOT
DETERMINISTIC' is given in the routine definition, the default is `NOT
DETERMINISTIC'.

A routine that contains the `NOW()' function (or its synonyms) or
`RAND()' is non-deterministic, but it might still be replication-safe.
For `NOW()', the binary log includes the timestamp and replicates
correctly.  `RAND()' also replicates correctly as long as it is called
only a single time during the execution of a routine. (You can consider
the routine execution timestamp and random number seed as implicit
inputs that are identical on the master and slave.)

Prior to MySQL 6.0.3, the `DETERMINISTIC' characteristic is accepted,
but not used by the optimizer.  However, if binary logging is enabled,
this characteristic always affects which routine definitions MySQL
accepts. See *Note stored-programs-logging::.

Several characteristics provide information about the nature of data
use by the routine. In MySQL, these characteristics are advisory only.
The server does not use them to constrain what kinds of statements a
routine will be allowed to execute.

   * `CONTAINS SQL' indicates that the routine does not contain
     statements that read or write data. This is the default if none of
     these characteristics is given explicitly. Examples of such
     statements are `SET @x = 1' or `DO RELEASE_LOCK('abc')', which
     execute but neither read nor write data.

   * `NO SQL' indicates that the routine contains no SQL statements.

   * `READS SQL DATA' indicates that the routine contains statements
     that read data (for example, *Note `SELECT': select.), but not
     statements that write data.

   * `MODIFIES SQL DATA' indicates that the routine contains statements
     that may write data (for example, *Note `INSERT': insert. or *Note
     `DELETE': delete.).

The `SQL SECURITY' characteristic can be used to specify whether the
routine should be executed using the permissions of the user who
creates the routine or the user who invokes it. The default value is
`DEFINER'. This feature is new in SQL:2003. The creator or invoker must
have permission to access the database with which the routine is
associated. It is necessary to have the `EXECUTE' privilege to be able
to execute the routine. The user that must have this privilege is
either the definer or invoker, depending on how the `SQL SECURITY'
characteristic is set.

The `COMMENT' characteristic is a MySQL extension, and may be used to
describe the stored routine. This information is displayed by the *Note
`SHOW CREATE PROCEDURE': show-create-procedure. and *Note `SHOW CREATE
FUNCTION': show-create-function. statements.

The optional `DEFINER' clause specifies the MySQL account to be used
when checking access privileges at routine execution time for routines
that have the `SQL SECURITY DEFINER' characteristic.

If a USER value is given for the `DEFINER' clause, it should be a MySQL
account in `'USER_NAME'@'HOST_NAME'' format (the same format used in the
*Note `GRANT': grant. statement). The USER_NAME and HOST_NAME values
both are required. The definer can also be given as `CURRENT_USER' or
`CURRENT_USER()'. The default `DEFINER' value is the user who executes
the *Note `CREATE PROCEDURE': create-procedure. or *Note `CREATE
FUNCTION': create-function. or statement. (This is the same as `DEFINER
= CURRENT_USER'.)

If you specify the `DEFINER' clause, these rules determine the legal
`DEFINER' user values:

   * If you do not have the `SUPER' privilege, the only legal USER
     value is your own account, either specified literally or by using
     `CURRENT_USER'. You cannot set the definer to some other account.

   * If you have the `SUPER' privilege, you can specify any
     syntactically legal account name. If the account does not actually
     exist, a warning is generated.

   * Although it is possible to create routines with a non-existent
     `DEFINER' value, an error occurs if the routine executes with
     definer privileges but the definer does not exist at execution
     time.

Within a stored routine that is defined with the `SQL SECURITY DEFINER'
characteristic, `CURRENT_USER' returns the routine's `DEFINER' value.
For information about user auditing within stored routines, see *Note
account-activity-auditing::.

Consider the following procedure, which displays a count of the number
of MySQL accounts listed in the `mysql.user' table:

     CREATE DEFINER = 'admin'@'localhost' PROCEDURE account_count()
     BEGIN
       SELECT 'Number of accounts:', COUNT(*) FROM mysql.user;
     END;

The procedure is assigned a `DEFINER' account of `'admin'@'localhost''
no matter which user defines it. It executes with the privileges of
that account no matter which user invokes it (because the default
security characteristic is `DEFINER'). The procedure succeeds or fails
depending on whether `'admin'@'localhost'' has the `EXECUTE' privilege
for it and the `SELECT' privilege for the `mysql.user' table.

Now suppose that the procedure is defined with the `SQL SECURITY
INVOKER' characteristic:

     CREATE DEFINER = 'admin'@'localhost' PROCEDURE account_count()
     SQL SECURITY INVOKER
     BEGIN
       SELECT 'Number of accounts:', COUNT(*) FROM mysql.user;
     END;

The procedure still has a `DEFINER' of `'admin'@'localhost'', but in
this case, it executes with the privileges of the invoking user. Thus,
the procedure succeeds or fails depending on whether the invoker has
the required privileges.

The server uses the data type of a routine parameter or function return
value as follows. These rules also apply to local routine variables
created with the *Note `DECLARE': declare.  statement (*Note
declare-local-variable::).

   * Assignments are checked for data type mismatches and overflow.
     Conversion and overflow problems result in warnings, or errors in
     strict mode.

   * Only scalar values can be assigned to parameters or variables.
     For example, a statement such as `SET x = (SELECT 1, 2)' is
     invalid.

   * For character data types, if there is a `CHARACTER SET' clause in
     the declaration, the specified character set and its default
     collation are used. If there is no such clause, the database
     character set and collation that are in effect at the time the
     routine is created are used.  (These are given by the values of the
     `character_set_database' and `collation_database' system
     variables.) The `COLLATE' attribute is not supported. (This
     includes use of `BINARY', because in this context `BINARY'
     specifies the binary collation of the character set.)


File: manual.info,  Node: create-server,  Next: create-table,  Prev: create-procedure,  Up: sql-syntax-data-definition

12.1.13 `CREATE SERVER' Syntax
------------------------------

     CREATE SERVER SERVER_NAME
         FOREIGN DATA WRAPPER WRAPPER_NAME
         OPTIONS (OPTION [, OPTION] ...)

     OPTION:
       { HOST CHARACTER-LITERAL
       | DATABASE CHARACTER-LITERAL
       | USER CHARACTER-LITERAL
       | PASSWORD CHARACTER-LITERAL
       | SOCKET CHARACTER-LITERAL
       | OWNER CHARACTER-LITERAL
       | PORT NUMERIC-LITERAL }

This statement creates the definition of a server for use with the
`FEDERATED' storage engine. The *Note `CREATE SERVER': create-server.
statement creates a new row within the `servers' table within the
`mysql' database. This statement requires the `SUPER' privilege.

The `SERVER_NAME' should be a unique reference to the server. Server
definitions are global within the scope of the server, it is not
possible to qualify the server definition to a specific database.
`SERVER_NAME' has a maximum length of 64 characters (names longer than
64 characters are silently truncated), and is case insensitive. You may
specify the name as a quoted string.

The `WRAPPER_NAME' should be `mysql', and may be quoted with single
quotes. Other values for `WRAPPER_NAME' are not currently supported.

For each `OPTION' you must specify either a character literal or
numeric literal.  Character literals are UTF-8, support a maximum
length of 64 characters and default to a blank (empty) string. String
literals are silently truncated to 64 characters. Numeric literals must
be a number between 0 and 9999, default value is 0.

The *Note `CREATE SERVER': create-server. statement creates an entry in
the `mysql.server' table that can later be used with the *Note `CREATE
TABLE': create-table.  statement when creating a `FEDERATED' table. The
options that you specify will be used to populate the columns in the
`mysql.server' table. The table columns are `Server_name', `Host',
`Db', `Username', `Password', `Port' and `Socket'.

*Note*:

Note that the `OWNER' option is currently not applied, and has no
effect on the ownership or operation of the server connection that is
created.

For example:

     CREATE SERVER s
     FOREIGN DATA WRAPPER mysql
     OPTIONS (USER 'Remote', HOST '192.168.1.106', DATABASE 'test');

The data stored in the table can be used when creating a connection to
a `FEDERATED' table:

     CREATE TABLE t (s1 INT) ENGINE=FEDERATED CONNECTION='s';

For more information, see *Note federated-storage-engine::.

*Note `CREATE SERVER': create-server. does not cause an automatic
commit.


File: manual.info,  Node: create-table,  Next: create-trigger,  Prev: create-server,  Up: sql-syntax-data-definition

12.1.14 `CREATE TABLE' Syntax
-----------------------------

* Menu:

* silent-column-changes::        Silent Column Specification Changes

     CREATE [TEMPORARY] TABLE [IF NOT EXISTS] TBL_NAME
         (CREATE_DEFINITION,...)
         [TABLE_OPTION] ...
         [PARTITION_OPTIONS]

Or:

     CREATE [TEMPORARY] TABLE [IF NOT EXISTS] TBL_NAME
         [(CREATE_DEFINITION,...)]
         [TABLE_OPTION] ...
         [PARTITION_OPTIONS]
         SELECT_STATEMENT

Or:

     CREATE [TEMPORARY] TABLE [IF NOT EXISTS] TBL_NAME
         { LIKE OLD_TBL_NAME | (LIKE OLD_TBL_NAME) }

     CREATE_DEFINITION:
         COL_NAME COLUMN_DEFINITION
       | [CONSTRAINT [SYMBOL]] PRIMARY KEY [INDEX_TYPE] (INDEX_COL_NAME,...)
           [INDEX_OPTION] ...
       | {INDEX|KEY} [INDEX_NAME] [INDEX_TYPE] (INDEX_COL_NAME,...)
           [INDEX_OPTION] ...
       | [CONSTRAINT [SYMBOL]] UNIQUE [INDEX|KEY]
           [INDEX_NAME] [INDEX_TYPE] (INDEX_COL_NAME,...)
           [INDEX_OPTION] ...
       | {FULLTEXT|SPATIAL} [INDEX|KEY] [INDEX_NAME] (INDEX_COL_NAME,...)
           [INDEX_OPTION] ...
       | [CONSTRAINT [SYMBOL]] FOREIGN KEY
           [INDEX_NAME] (INDEX_COL_NAME,...) REFERENCE_DEFINITION
       | [CONSTRAINT [SYMBOL]] CHECK (EXPR)

     COLUMN_DEFINITION:
         DATA_TYPE [NOT NULL | NULL] [DEFAULT DEFAULT_VALUE]
           [AUTO_INCREMENT] [UNIQUE [KEY] | [PRIMARY] KEY]
           [COMMENT 'STRING'] [REFERENCE_DEFINITION]

     DATA_TYPE:
         BIT[(LENGTH)]
       | TINYINT[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | SMALLINT[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | MEDIUMINT[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | INT[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | INTEGER[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | BIGINT[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | REAL[(LENGTH,DECIMALS)] [UNSIGNED] [ZEROFILL]
       | DOUBLE[(LENGTH,DECIMALS)] [UNSIGNED] [ZEROFILL]
       | FLOAT[(LENGTH,DECIMALS)] [UNSIGNED] [ZEROFILL]
       | DECIMAL[(LENGTH[,DECIMALS])] [UNSIGNED] [ZEROFILL]
       | NUMERIC[(LENGTH[,DECIMALS])] [UNSIGNED] [ZEROFILL]
       | DATE
       | TIME
       | TIMESTAMP
       | DATETIME
       | YEAR
       | CHAR[(LENGTH)]
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | VARCHAR(LENGTH)
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | BINARY[(LENGTH)]
       | VARBINARY(LENGTH)
       | TINYBLOB
       | BLOB
       | MEDIUMBLOB
       | LONGBLOB
       | TINYTEXT [BINARY]
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | TEXT [BINARY]
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | MEDIUMTEXT [BINARY]
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | LONGTEXT [BINARY]
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | ENUM(VALUE1,VALUE2,VALUE3,...)
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | SET(VALUE1,VALUE2,VALUE3,...)
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | SPATIAL_TYPE

     INDEX_COL_NAME:
         COL_NAME [(LENGTH)] [ASC | DESC]

     INDEX_TYPE:
         USING {BTREE | HASH | RTREE}

     INDEX_OPTION:
         KEY_BLOCK_SIZE [=] VALUE
       | INDEX_TYPE
       | WITH PARSER PARSER_NAME
       | COMMENT 'STRING'

     REFERENCE_DEFINITION:
         REFERENCES TBL_NAME (INDEX_COL_NAME,...)
           [MATCH FULL | MATCH PARTIAL | MATCH SIMPLE]
           [ON DELETE REFERENCE_OPTION]
           [ON UPDATE REFERENCE_OPTION]

     REFERENCE_OPTION:
         RESTRICT | CASCADE | SET NULL | NO ACTION

     TABLE_OPTION:
         ENGINE [=] ENGINE_NAME
       | AUTO_INCREMENT [=] VALUE
       | AVG_ROW_LENGTH [=] VALUE
       | [DEFAULT] CHARACTER SET [=] CHARSET_NAME
       | CHECKSUM [=] {0 | 1}
       | [DEFAULT] COLLATE [=] COLLATION_NAME
       | COMMENT [=] 'STRING'
       | CONNECTION [=] 'CONNECT_STRING'
       | DATA DIRECTORY [=] 'ABSOLUTE PATH TO DIRECTORY'
       | DELAY_KEY_WRITE [=] {0 | 1}
       | INDEX DIRECTORY [=] 'ABSOLUTE PATH TO DIRECTORY'
       | INSERT_METHOD [=] { NO | FIRST | LAST }
       | KEY_BLOCK_SIZE [=] VALUE
       | MAX_ROWS [=] VALUE
       | MIN_ROWS [=] VALUE
       | PACK_KEYS [=] {0 | 1 | DEFAULT}
       | PASSWORD [=] 'STRING'
       | ROW_FORMAT [=] {DEFAULT|DYNAMIC|FIXED|COMPRESSED|REDUNDANT|COMPACT}
       | TABLESPACE TABLESPACE_NAME
       | UNION [=] (TBL_NAME[,TBL_NAME]...)

     PARTITION_OPTIONS:
         PARTITION BY
             { [LINEAR] HASH(EXPR)
             | [LINEAR] KEY(COLUMN_LIST)
             | RANGE(EXPR)
             | LIST(EXPR) }
         [PARTITIONS NUM]
         [SUBPARTITION BY
             { [LINEAR] HASH(EXPR)
             | [LINEAR] KEY(COLUMN_LIST) }
           [SUBPARTITIONS NUM]
         ]
         [(PARTITION_DEFINITION [, PARTITION_DEFINITION] ...)]

     PARTITION_DEFINITION:
         PARTITION PARTITION_NAME
             [VALUES {LESS THAN {(EXPR) | `MAXVALUE'} | IN (VALUE_LIST)}]
             [[STORAGE] ENGINE [=] ENGINE_NAME]
             [COMMENT [=] 'COMMENT_TEXT' ]
             [DATA DIRECTORY [=] '`DATA_DIR'']
             [INDEX DIRECTORY [=] '`INDEX_DIR'']
             [MAX_ROWS [=] MAX_NUMBER_OF_ROWS]
             [MIN_ROWS [=] MIN_NUMBER_OF_ROWS]
             [TABLESPACE [=] TABLESPACE_NAME]
             [NODEGROUP [=] NODE_GROUP_ID]
             [(SUBPARTITION_DEFINITION [, SUBPARTITION_DEFINITION] ...)]

     SUBPARTITION_DEFINITION:
         SUBPARTITION LOGICAL_NAME
             [[STORAGE] ENGINE [=] ENGINE_NAME]
             [COMMENT [=] 'COMMENT_TEXT' ]
             [DATA DIRECTORY [=] '`DATA_DIR'']
             [INDEX DIRECTORY [=] '`INDEX_DIR'']
             [MAX_ROWS [=] MAX_NUMBER_OF_ROWS]
             [MIN_ROWS [=] MIN_NUMBER_OF_ROWS]
             [TABLESPACE [=] TABLESPACE_NAME]
             [NODEGROUP [=] NODE_GROUP_ID]

     SELECT_STATEMENT:
         [IGNORE | REPLACE] [AS] SELECT ...   (SOME LEGAL SELECT STATEMENT)

*Note `CREATE TABLE': create-table. creates a table with the given
name. You must have the `CREATE' privilege for the table.

Rules for allowable table names are given in *Note identifiers::. By
default, the table is created in the default database. An error occurs
if the table exists, if there is no default database, or if the
database does not exist.

The table name can be specified as DB_NAME.TBL_NAME to create the table
in a specific database. This works regardless of whether there is a
default database, assuming that the database exists. If you use quoted
identifiers, quote the database and table names separately.  For
example, write ``mydb`.`mytbl`', not ``mydb.mytbl`'.

You can use the `TEMPORARY' keyword when creating a table. A
`TEMPORARY' table is visible only to the current connection, and is
dropped automatically when the connection is closed. This means that
two different connections can use the same temporary table name without
conflicting with each other or with an existing non-`TEMPORARY' table
of the same name. (The existing table is hidden until the temporary
table is dropped.) To create temporary tables, you must have the
`CREATE TEMPORARY TABLES' privilege.

*Note*:

*Note `CREATE TABLE': create-table. does not automatically commit the
current active transaction if you use the `TEMPORARY' keyword.

The keywords `IF NOT EXISTS' prevent an error from occurring if the
table exists. However, there is no verification that the existing table
has a structure identical to that indicated by the *Note `CREATE
TABLE': create-table.  statement.

*Note*:

If you use `IF NOT EXISTS' in a `CREATE TABLE ... SELECT' statement,
any rows selected by the *Note `SELECT': select. part are inserted
regardless of whether the table already exists.

MySQL represents each table by an `.frm' table format (definition) file
in the database directory. The storage engine for the table might
create other files as well. In the case of `MyISAM' tables, the storage
engine creates data and index files. Thus, for each `MyISAM' table
TBL_NAME, there are three disk files.

*File*                 *Purpose*
`TBL_NAME.frm'         Table format (definition) file
`TBL_NAME.MYD'         Data file
`TBL_NAME.MYI'         Index file

*Note storage-engines::, describes what files each storage engine
creates to represent tables. If a table name contains special
characters, the names for the table files contain encoded versions of
those characters as described in *Note identifier-mapping::.

DATA_TYPE represents the data type in a column definition. SPATIAL_TYPE
represents a spatial data type. The data type syntax shown is
representative only. For a full description of the syntax available for
specifying column data types, as well as information about the
properties of each type, see *Note data-types::, and *Note
spatial-extensions::.

Some attributes do not apply to all data types.  `AUTO_INCREMENT'
applies only to integer and floating-point types. `DEFAULT' does not
apply to the *Note `BLOB': blob. or *Note `TEXT': blob. types.

   * If neither `NULL' nor `NOT NULL' is specified, the column is
     treated as though `NULL' had been specified.

   * An integer or floating-point column can have the additional
     attribute `AUTO_INCREMENT'. When you insert a value of `NULL'
     (recommended) or `0' into an indexed `AUTO_INCREMENT' column, the
     column is set to the next sequence value. Typically this is
     `VALUE+1', where VALUE is the largest value for the column
     currently in the table.  `AUTO_INCREMENT' sequences begin with `1'.

     To retrieve an `AUTO_INCREMENT' value after inserting a row, use
     the `LAST_INSERT_ID()' SQL function or the *Note
     `mysql_insert_id()': mysql-insert-id. C API function. See *Note
     information-functions::, and *Note mysql-insert-id::.

     If the `NO_AUTO_VALUE_ON_ZERO' SQL mode is enabled, you can store
     `0' in `AUTO_INCREMENT' columns as `0' without generating a new
     sequence value.  See *Note server-sql-mode::.

     *Note*:

     There can be only one `AUTO_INCREMENT' column per table, it must
     be indexed, and it cannot have a `DEFAULT' value. An
     `AUTO_INCREMENT' column works properly only if it contains only
     positive values. Inserting a negative number is regarded as
     inserting a very large positive number. This is done to avoid
     precision problems when numbers `wrap' over from positive to
     negative and also to ensure that you do not accidentally get an
     `AUTO_INCREMENT' column that contains `0'.

     For `MyISAM' tables, you can specify an `AUTO_INCREMENT' secondary
     column in a multiple-column key. See *Note
     example-auto-increment::.

     To make MySQL compatible with some ODBC applications, you can find
     the `AUTO_INCREMENT' value for the last inserted row with the
     following query:

          SELECT * FROM TBL_NAME WHERE AUTO_COL IS NULL

     For information about `InnoDB' and `AUTO_INCREMENT', see *Note
     innodb-auto-increment-handling::.

   * Character data types (*Note `CHAR': char, *Note `VARCHAR': char,
     *Note `TEXT': blob.) can include `CHARACTER SET' and `COLLATE'
     attributes to specify the character set and collation for the
     column. For details, see *Note charset::. `CHARSET' is a synonym
     for `CHARACTER SET'. Example:

          CREATE TABLE t (c CHAR(20) CHARACTER SET utf8 COLLATE utf8_bin);

     MySQL 6.0 interprets length specifications in character column
     definitions in characters. (Versions before MySQL 4.1 interpreted
     them in bytes.) Lengths for *Note `BINARY': binary-varbinary. and
     *Note `VARBINARY': binary-varbinary. are in bytes.

   * The `DEFAULT' clause specifies a default value for a column. With
     one exception, the default value must be a constant; it cannot be
     a function or an expression. This means, for example, that you
     cannot set the default for a date column to be the value of a
     function such as `NOW()' or `CURRENT_DATE'. The exception is that
     you can specify `CURRENT_TIMESTAMP' as the default for a *Note
     `TIMESTAMP': datetime. column.  See *Note timestamp::.

     If a column definition includes no explicit `DEFAULT' value, MySQL
     determines the default value as described in *Note
     data-type-defaults::.

     *Note `BLOB': blob. and *Note `TEXT': blob. columns cannot be
     assigned a default value.

     *Note `CREATE TABLE': create-table. fails if a date-valued default
     is not correct according to the `NO_ZERO_IN_DATE' SQL mode, even
     if strict SQL mode is not enabled. For example, `c1 DATE DEFAULT
     '2010-00-00'' causes *Note `CREATE TABLE': create-table. to fail
     with `Invalid default value for 'c1''.

   * A comment for a column can be specified with the `COMMENT' option,
     up to 1024 characters long.  The comment is displayed by the *Note
     `SHOW CREATE TABLE': show-create-table. and *Note `SHOW FULL
     COLUMNS': show-columns. statements.

   * `KEY' is normally a synonym for `INDEX'. The key attribute `PRIMARY
     KEY' can also be specified as just `KEY' when given in a column
     definition. This was implemented for compatibility with other
     database systems.

   * A `UNIQUE' index creates a constraint such that all values in the
     index must be distinct. An error occurs if you try to add a new
     row with a key value that matches an existing row. For all
     engines, a `UNIQUE' index allows multiple `NULL' values for
     columns that can contain `NULL'.

   * A `PRIMARY KEY' is a unique index where all key columns must be
     defined as `NOT NULL'. If they are not explicitly declared as `NOT
     NULL', MySQL declares them so implicitly (and silently). A table
     can have only one `PRIMARY KEY'. If you do not have a `PRIMARY
     KEY' and an application asks for the `PRIMARY KEY' in your tables,
     MySQL returns the first `UNIQUE' index that has no `NULL' columns
     as the `PRIMARY KEY'.

     In `InnoDB' tables, having a long `PRIMARY KEY' wastes a lot of
     space. (See *Note innodb-table-and-index::.)

   * In the created table, a `PRIMARY KEY' is placed first, followed by
     all `UNIQUE' indexes, and then the non-unique indexes. This helps
     the MySQL optimizer to prioritize which index to use and also more
     quickly to detect duplicated `UNIQUE' keys.

   * A `PRIMARY KEY' can be a multiple-column index. However, you
     cannot create a multiple-column index using the `PRIMARY KEY' key
     attribute in a column specification. Doing so only marks that
     single column as primary. You must use a separate `PRIMARY
     KEY(INDEX_COL_NAME, ...)' clause.

   * If a `PRIMARY KEY' or `UNIQUE' index consists of only one column
     that has an integer type, you can also refer to the column as
     `_rowid' in *Note `SELECT': select. statements.

   * In MySQL, the name of a `PRIMARY KEY' is `PRIMARY'. For other
     indexes, if you do not assign a name, the index is assigned the
     same name as the first indexed column, with an optional suffix
     (`_2', `_3', `...') to make it unique. You can see index names for
     a table using `SHOW INDEX FROM TBL_NAME'. See *Note show-index::.

   * Some storage engines allow you to specify an index type when
     creating an index. The syntax for the INDEX_TYPE specifier is
     `USING TYPE_NAME'.

     Example:

          CREATE TABLE lookup
            (id INT, INDEX USING BTREE (id))
            ENGINE = MEMORY;

     The `USING' clause should be given after the column list.

     INDEX_OPTION values specify additional options for an index.
     `USING' is one such option. For details about allowable
     INDEX_OPTION values, see *Note create-index::.

     For more information about indexes, see *Note mysql-indexes::.

   * In MySQL 6.0, only the `MyISAM', `InnoDB', and `MEMORY' storage
     engines support indexes on columns that can have `NULL' values. In
     other cases, you must declare indexed columns as `NOT NULL' or an
     error results.

   * For *Note `CHAR': char, *Note `VARCHAR': char, *Note `BINARY':
     binary-varbinary, and *Note `VARBINARY': binary-varbinary.
     columns, indexes can be created that use only the leading part of
     column values, using `COL_NAME(LENGTH)' syntax to specify an index
     prefix length.  *Note `BLOB': blob. and *Note `TEXT': blob.
     columns also can be indexed, but a prefix length _must_ be given.
     Prefix lengths are given in characters for non-binary string types
     and in bytes for binary string types. That is, index entries
     consist of the first LENGTH characters of each column value for
     *Note `CHAR': char, *Note `VARCHAR': char, and *Note `TEXT': blob.
     columns, and the first LENGTH bytes of each column value for *Note
     `BINARY': binary-varbinary, *Note `VARBINARY': binary-varbinary,
     and *Note `BLOB': blob. columns. Indexing only a prefix of column
     values like this can make the index file much smaller. See *Note
     indexes::.

     Only the `MyISAM' and `InnoDB' storage engines support indexing on
     *Note `BLOB': blob. and *Note `TEXT': blob. columns. For example:

          CREATE TABLE test (blob_col BLOB, INDEX(blob_col(10)));

     Prefixes can be up to 1000 bytes long (767 bytes for `InnoDB'
     tables). Note that prefix limits are measured in bytes, whereas
     the prefix length in *Note `CREATE TABLE': create-table.
     statements is interpreted as number of characters for non-binary
     data types (*Note `CHAR': char, *Note `VARCHAR': char, *Note
     `TEXT': blob.). Take this into account when specifying a prefix
     length for a column that uses a multi-byte character set.

   * An INDEX_COL_NAME specification can end with `ASC' or `DESC'.
     These keywords are allowed for future extensions for specifying
     ascending or descending index value storage.  Currently, they are
     parsed but ignored; index values are always stored in ascending
     order.

   * When you use `ORDER BY' or `GROUP BY' on a *Note `TEXT': blob. or
     *Note `BLOB': blob. column in a *Note `SELECT': select, the server
     sorts values using only the initial number of bytes indicated by
     the `max_sort_length' system variable. See *Note blob::.

   * You can create special `FULLTEXT' indexes, which are used for
     full-text searches. Only the `MyISAM' storage engine supports
     `FULLTEXT' indexes. They can be created only from *Note `CHAR':
     char, *Note `VARCHAR': char, and *Note `TEXT': blob. columns.
     Indexing always happens over the entire column; column prefix
     indexing is not supported and any prefix length is ignored if
     specified. See *Note fulltext-search::, for details of operation. A
     `WITH PARSER' clause can be specified as an INDEX_OPTION value to
     associate a parser plugin with the index if full-text indexing and
     searching operations need special handling. This clause is legal
     only for `FULLTEXT' indexes. See *Note plugin-api::, for details
     on creating plugins.

   * You can create `SPATIAL' indexes on spatial data types. Spatial
     types are supported only for `MyISAM' tables and indexed columns
     must be declared as `NOT NULL'. See *Note spatial-extensions::.

   * Index definitions can include an optional comment of up to 1024
     characters.

   * `InnoDB' tables support checking of foreign key constraints. See
     *Note innodb::. Note that the `FOREIGN KEY' syntax in `InnoDB' is
     more restrictive than the syntax presented for the *Note `CREATE
     TABLE': create-table.  statement at the beginning of this section:
     The columns of the referenced table must always be explicitly
     named.  `InnoDB' supports both `ON DELETE' and `ON UPDATE' actions
     on foreign keys. For the precise syntax, see *Note
     innodb-foreign-key-constraints::.

     For other storage engines, MySQL Server parses and ignores the
     `FOREIGN KEY' and `REFERENCES' syntax in *Note `CREATE TABLE':
     create-table. statements. The `CHECK' clause is parsed but ignored
     by all storage engines. See *Note ansi-diff-foreign-keys::.

     *Important*:

     For users familiar with the ANSI/ISO SQL Standard, please note
     that no storage engine, including `InnoDB', recognizes or enforces
     the `MATCH' clause used in referential integrity constraint
     definitions. Use of an explicit `MATCH' clause will not have the
     specified effect, and also causes `ON DELETE' and `ON UPDATE'
     clauses to be ignored. For these reasons, specifying `MATCH'
     should be avoided.

     The `MATCH' clause in the SQL standard controls how `NULL' values
     in a composite (multiple-column) foreign key are handled when
     comparing to a primary key. `InnoDB' essentially implements the
     semantics defined by `MATCH SIMPLE', which allow a foreign key to
     be all or partially `NULL'. In that case, the (child table) row
     containing such a foreign key is allowed to be inserted, and does
     not match any row in the referenced (parent) table. It is possible
     to implement other semantics using triggers.

     Additionally, MySQL and `InnoDB' require that the referenced
     columns be indexed for performance.  However, the system does not
     enforce a requirement that the referenced columns be `UNIQUE' or be
     declared `NOT NULL'. The handling of foreign key references to
     non-unique keys or keys that contain `NULL' values is not well
     defined for operations such as *Note `UPDATE': update.  or `DELETE
     CASCADE'. You are advised to use foreign keys that reference only
     `UNIQUE' and `NOT NULL' keys.

     Furthermore, `InnoDB' does not recognize or support `inline
     `REFERENCES' specifications' (as defined in the SQL standard)
     where the references are defined as part of the column
     specification. `InnoDB' accepts `REFERENCES' clauses only when
     specified as part of a separate `FOREIGN KEY' specification. For
     other storage engines, MySQL Server parses and ignores foreign key
     specifications.

     *Note*:

     Partitioned tables do not support foreign keys. See *Note
     partitioning-limitations::, for more information.

   * There is a hard limit of 4096 columns per table, but the effective
     maximum may be less for a given table and depends on the factors
     discussed in *Note column-count-limit::.

The `ENGINE' table option specifies the storage engine for the table.

The `ENGINE' table option takes the storage engine names shown in the
following table.

*Storage Engine*   *Description*
`ARCHIVE'          The archiving storage engine. See *Note
                   archive-storage-engine::.
`CSV'              Tables that store rows in comma-separated values
                   format. See *Note csv-storage-engine::.
`EXAMPLE'          An example engine. See *Note
                   example-storage-engine::.
`FEDERATED'        Storage engine that accesses remote tables. See
                   *Note federated-storage-engine::.
`HEAP'             This is a synonym for `MEMORY'.
`ISAM'             Not available in MySQL 6.0. If you are upgrading
(_OBSOLETE_)       to MySQL 6.0 from a previous version, you should
                   convert any existing `ISAM' tables to `MyISAM'
                   _before_ performing the upgrade.
`InnoDB'           Transaction-safe tables with row locking and
                   foreign keys. See *Note innodb::.
`MEMORY'           The data for this storage engine is stored only
                   in memory. See *Note memory-storage-engine::.
`MERGE'            A collection of `MyISAM' tables used as one
                   table. Also known as `MRG_MyISAM'. See *Note
                   merge-storage-engine::.
`MyISAM'           The binary portable storage engine that is the
                   default storage engine used by MySQL. See *Note
                   myisam-storage-engine::.

If a storage engine is specified that is not available, MySQL uses the
default engine instead. Normally, this is `MyISAM'. For example, if a
table definition includes the `ENGINE=INNODB' option but the MySQL
server does not support `INNODB' tables, the table is created as a
`MyISAM' table. This makes it possible to have a replication setup
where you have transactional tables on the master but tables created on
the slave are non-transactional (to get more speed). In MySQL 6.0, a
warning occurs if the storage engine specification is not honored.

Engine substitution can be controlled by the setting of the
`NO_ENGINE_SUBSTITUTION' SQL mode, as described in *Note
server-sql-mode::.

*Note*:

The older `TYPE' option was synonymous with `ENGINE'. `TYPE' was
deprecated in MySQL 4.0, and removed in MySQL 5.2.  _When upgrading to
MySQL 5.2 or later, you must convert existing applications that rely on
`TYPE' to use `ENGINE' instead_.

The other table options are used to optimize the behavior of the table.
In most cases, you do not have to specify any of them.  These options
apply to all storage engines unless otherwise indicated. Options that
do not apply to a given storage engine may be accepted and remembered
as part of the table definition. Such options then apply if you later
use *Note `ALTER TABLE': alter-table. to convert the table to use a
different storage engine.

   * `AUTO_INCREMENT'

     The initial `AUTO_INCREMENT' value for the table. In MySQL 6.0,
     this works for `MyISAM', `MEMORY', `InnoDB', `ARCHIVE' and
     `Falcon' tables. To set the first auto-increment value for engines
     that do not support the `AUTO_INCREMENT' table option, insert a
     `dummy' row with a value one less than the desired value after
     creating the table, and then delete the dummy row.

     For engines that support the `AUTO_INCREMENT' table option in
     *Note `CREATE TABLE': create-table.  statements, you can also use
     `ALTER TABLE TBL_NAME AUTO_INCREMENT = N' to reset the
     `AUTO_INCREMENT' value. The value cannot be set lower than the
     maximum value currently in the column.

   * `AVG_ROW_LENGTH'

     An approximation of the average row length for your table. You
     need to set this only for large tables with variable-size rows.

     When you create a `MyISAM' table, MySQL uses the product of the
     `MAX_ROWS' and `AVG_ROW_LENGTH' options to decide how big the
     resulting table is. If you don't specify either option, the
     maximum size for `MyISAM' data and index files is 256TB by
     default. (If your operating system does not support files that
     large, table sizes are constrained by the file size limit.) If you
     want to keep down the pointer sizes to make the index smaller and
     faster and you don't really need big files, you can decrease the
     default pointer size by setting the `myisam_data_pointer_size'
     system variable. (See *Note server-system-variables::.) If you
     want all your tables to be able to grow above the default limit
     and are willing to have your tables slightly slower and larger than
     necessary, you can increase the default pointer size by setting
     this variable. Setting the value to 7 allows table sizes up to
     65,536TB.

   * `[DEFAULT] CHARACTER SET'

     Specify a default character set for the table.  `CHARSET' is a
     synonym for `CHARACTER SET'. If the character set name is
     `DEFAULT', the database character set is used.

   * `CHECKSUM'

     Set this to 1 if you want MySQL to maintain a live checksum for
     all rows (that is, a checksum that MySQL updates automatically as
     the table changes). This makes the table a little slower to
     update, but also makes it easier to find corrupted tables. The
     *Note `CHECKSUM TABLE': checksum-table. statement reports the
     checksum.  (`MyISAM' only.)

   * `[DEFAULT] COLLATE'

     Specify a default collation for the table.

   * `COMMENT'

     A comment for the table, up to 2048 characters long. (Before
     5.2.4, the limit is 60 characters.)

   * `CONNECTION'

     The connection string for a `FEDERATED' table.

     *Note*:

     Older versions of MySQL used a `COMMENT' option for the connection
     string.

   * `DATA DIRECTORY', `INDEX DIRECTORY'

     By using `DATA DIRECTORY='DIRECTORY'' or `INDEX
     DIRECTORY='DIRECTORY'' you can specify where the `MyISAM' storage
     engine should put a table's data file and index file. The directory
     must be the full path name to the directory, not a relative path.

     *Important*:

     Beginning with MySQL 6.0.4, table-level `DATA DIRECTORY' and
     `INDEX DIRECTORY' options are ignored for partitioned tables.
     (Bug#32091 (http://bugs.mysql.com/32091))

     These options work only when you are not using the
     `--skip-symbolic-links' option. Your operating system must also
     have a working, thread-safe `realpath()' call. See *Note
     symbolic-links-to-tables::, for more complete information.

     If a `MyISAM' table is created with no `DATA DIRECTORY' option, the
     `.MYD' file is created in the database directory. By default, if
     `MyISAM' finds an existing `.MYD' file in this case, it overwrites
     it. The same applies to `.MYI' files for tables created with no
     `INDEX DIRECTORY' option. To suppress this behavior, start the
     server with the `--keep_files_on_create' option, in which case
     `MyISAM' will not overwrite existing files and returns an error
     instead.

     If a `MyISAM' table is created with a `DATA DIRECTORY' or `INDEX
     DIRECTORY' option and an existing `.MYD' or `.MYI' file is found,
     MyISAM always returns an error. It will not overwrite a file in
     the specified directory.

     *Important*:

     Beginning with MySQL 6.0.5, you cannot use path names that contain
     the MySQL data directory with `DATA DIRECTORY' or `INDEX
     DIRECTORY'.  This includes partitioned tables and individual table
     partitions. (See Bug#32167 (http://bugs.mysql.com/32167).)

   * `DELAY_KEY_WRITE'

     Set this to 1 if you want to delay key updates for the table until
     the table is closed. See the description of the `delay_key_write'
     system variable in *Note server-system-variables::.  (`MyISAM'
     only.)

   * `INSERT_METHOD'

     If you want to insert data into a `MERGE' table, you must specify
     with `INSERT_METHOD' the table into which the row should be
     inserted.  `INSERT_METHOD' is an option useful for `MERGE' tables
     only. Use a value of `FIRST' or `LAST' to have inserts go to the
     first or last table, or a value of `NO' to prevent inserts. See
     *Note merge-storage-engine::.

   * `KEY_BLOCK_SIZE'

     This option provides a hint to the storage engine about the size
     in bytes to use for index key blocks. The engine is allowed to
     change the value if necessary. A value of 0 indicates that the
     default value should be used. Individual index definitions can
     specify a `KEY_BLOCK_SIZE' value of their own to override the
     table value.

   * `MAX_ROWS'

     The maximum number of rows you plan to store in the table.  This
     is not a hard limit, but rather a hint to the storage engine that
     the table must be able to store at least this many rows.

   * `MIN_ROWS'

     The minimum number of rows you plan to store in the table. The
     `MEMORY' storage engine uses this option as a hint about memory
     use.

   * `PACK_KEYS'

     `PACK_KEYS' takes effect only with `MyISAM' tables. Set this
     option to 1 if you want to have smaller indexes. This usually
     makes updates slower and reads faster. Setting the option to 0
     disables all packing of keys. Setting it to `DEFAULT' tells the
     storage engine to pack only long *Note `CHAR': char, *Note
     `VARCHAR': char, *Note `BINARY': binary-varbinary, or *Note
     `VARBINARY': binary-varbinary. columns.

     If you do not use `PACK_KEYS', the default is to pack strings, but
     not numbers. If you use `PACK_KEYS=1', numbers are packed as well.

     When packing binary number keys, MySQL uses prefix compression:

        * Every key needs one extra byte to indicate how many bytes of
          the previous key are the same for the next key.

        * The pointer to the row is stored in high-byte-first order
          directly after the key, to improve compression.

     This means that if you have many equal keys on two consecutive
     rows, all following `same' keys usually only take two bytes
     (including the pointer to the row). Compare this to the ordinary
     case where the following keys takes `storage_size_for_key +
     pointer_size' (where the pointer size is usually 4). Conversely,
     you get a significant benefit from prefix compression only if you
     have many numbers that are the same. If all keys are totally
     different, you use one byte more per key, if the key is not a key
     that can have `NULL' values. (In this case, the packed key length
     is stored in the same byte that is used to mark if a key is
     `NULL'.)

   * `PASSWORD'

     This option is unused. If you have a need to scramble your `.frm'
     files and make them unusable to any other MySQL server, please
     contact our sales department.

   * `RAID_TYPE'

     `RAID' support has been removed as of MySQL 5.0. For information
     on `RAID', see `CREATE TABLE' Syntax
     (http://dev.mysql.com/doc/refman/4.1/en/create-table.html).

   * `ROW_FORMAT'

     Defines how the rows should be stored. For `MyISAM' tables, the
     option value can be *Note `FIXED': numeric-types. or `DYNAMIC' for
     static or variable-length row format. *Note `myisampack':
     myisampack. sets the type to `COMPRESSED'. See *Note
     myisam-table-formats::.

     For `InnoDB' tables, rows are stored in compact format
     (`ROW_FORMAT=COMPACT') by default. The non-compact format used in
     older versions of MySQL can still be requested by specifying
     `ROW_FORMAT=REDUNDANT'.

     *Note*:

     When executing a *Note `CREATE TABLE': create-table.  statement,
     if you specify a row format which is not supported by the storage
     engine that is used for the table, the table is created using that
     storage engine's default row format. The information reported in
     this column in response to *Note `SHOW TABLE STATUS':
     show-table-status. is the actual row format used. This may differ
     from the value in the `Create_options' column because the original
     *Note `CREATE TABLE': create-table.  definition is retained during
     creation.

   * *Note `UNION': union.

     *Note `UNION': union. is used when you want to access a collection
     of identical `MyISAM' tables as one. This works only with `MERGE'
     tables. See *Note merge-storage-engine::.

     You must have `SELECT', `UPDATE', and `DELETE' privileges for the
     tables you map to a `MERGE' table.

     *Note*:

     Formerly, all tables used had to be in the same database as the
     `MERGE' table itself. This restriction no longer applies.

PARTITION_OPTIONS can be used to control partitioning of the table
created with *Note `CREATE TABLE': create-table.

*Important*:

Not all options shown in the syntax for PARTITION_OPTIONS at the
beginning of this section are available for all partitioning types.
Please see the listings for the following individual types for
information specific to each type, and see *Note partitioning::, for
more complete information about the workings of and uses for
partitioning in MySQL, as well as additional examples of table creation
and other statements relating to MySQL partitioning.

If used, a PARTITION_OPTIONS clause begins with `PARTITION BY'. This
clause contains the function that is used to determine the partition;
the function returns an integer value ranging from 1 to NUM, where NUM
is the number of partitions. (The maximum number of user-defined
partitions which a table may contain is 1024; the number of
subpartitions -- discussed later in this section -- is included in this
maximum.) The choices that are available for this function in MySQL 6.0
are shown in the following list:

   * `HASH(EXPR)': Hashes one or more columns to create a key for
     placing and locating rows. EXPR is an expression using one or more
     table columns. This can be any legal MySQL expression (including
     MySQL functions) that yields a single integer value. For example,
     these are all valid *Note `CREATE TABLE': create-table. statements
     using `PARTITION BY HASH':

          CREATE TABLE t1 (col1 INT, col2 CHAR(5))
              PARTITION BY HASH(col1);

          CREATE TABLE t1 (col1 INT, col2 CHAR(5))
              PARTITION BY HASH( ORD(col2) );

          CREATE TABLE t1 (col1 INT, col2 CHAR(5), col3 DATETIME)
              PARTITION BY HASH ( YEAR(col3) );

     You may not use either `VALUES LESS THAN' or `VALUES IN' clauses
     with `PARTITION BY HASH'.

     `PARTITION BY HASH' uses the remainder of EXPR divided by the
     number of partitions (that is, the modulus). For examples and
     additional information, see *Note partitioning-hash::.

     The `LINEAR' keyword entails a somewhat different algorithm. In
     this case, the number of the partition in which a row is stored is
     calculated as the result of one or more logical `AND' operations.
     For discussion and examples of linear hashing, see *Note
     partitioning-linear-hash::.

   * `KEY(COLUMN_LIST)': This is similar to `HASH', except that MySQL
     supplies the hashing function so as to guarantee an even data
     distribution. The COLUMN_LIST argument is simply a list of table
     columns. This example shows a simple table partitioned by key,
     with 4 partitions:

          CREATE TABLE tk (col1 INT, col2 CHAR(5), col3 DATE)
              PARTITION BY KEY(col3)
              PARTITIONS 4;

     For tables that are partitioned by key, you can employ linear
     partitioning by using the `LINEAR' keyword.  This has the same
     effect as with tables that are partitioned by `HASH'. That is, the
     partition number is found using the `&' operator rather than the
     modulus (see *Note partitioning-linear-hash::, and *Note
     partitioning-key::, for details). This example uses linear
     partitioning by key to distribute data between 5 partitions:

          CREATE TABLE tk (col1 INT, col2 CHAR(5), col3 DATE)
              PARTITION BY LINEAR KEY(col3)
              PARTITIONS 5;

     You may not use either `VALUES LESS THAN' or `VALUES IN' clauses
     with `PARTITION BY KEY'.

   * `RANGE': In this case, EXPR shows a range of values using a set of
     `VALUES LESS THAN' operators. When using range partitioning, you
     must define at least one partition using `VALUES LESS THAN'. You
     cannot use `VALUES IN' with range partitioning.

     `VALUES LESS THAN' can be used with either a literal value or an
     expression that evaluates to a single value.

     Suppose that you have a table that you wish to partition on a
     column containing year values, according to the following scheme.

     *Partition Number*:         *Years Range*:
     0                           1990 and earlier
     1                           1991 - 1994
     2                           1995 - 1998
     3                           1999 - 2002
     4                           2003 - 2005
     5                           2006 and later

     A table implementing such a partitioning scheme can be realized by
     the *Note `CREATE TABLE': create-table.  statement shown here:

          CREATE TABLE t1 (
              year_col  INT,
              some_data INT
          )
          PARTITION BY RANGE (year_col) (
              PARTITION p0 VALUES LESS THAN (1991),
              PARTITION p1 VALUES LESS THAN (1995),
              PARTITION p2 VALUES LESS THAN (1999),
              PARTITION p3 VALUES LESS THAN (2002),
              PARTITION p4 VALUES LESS THAN (2006),
              PARTITION p5 VALUES LESS THAN MAXVALUE
          );

     `PARTITION ... VALUES LESS THAN ...' statements work in a
     consecutive fashion. `VALUES LESS THAN MAXVALUE' works to specify
     `leftover' values that are greater than the maximum value
     otherwise specified.

     Note that `VALUES LESS THAN' clauses work sequentially in a manner
     similar to that of the `case' portions of a `switch ...  case'
     block (as found in many programming languages such as C, Java, and
     PHP). That is, the clauses must be arranged in such a way that the
     upper limit specified in each successive `VALUES LESS THAN' is
     greater than that of the previous one, with the one referencing
     `MAXVALUE' coming last of all in the list.

   * `LIST(EXPR)': This is useful when assigning partitions based on a
     table column with a restricted set of possible values, such as a
     state or country code. In such a case, all rows pertaining to a
     certain state or country can be assigned to a single partition, or
     a partition can be reserved for a certain set of states or
     countries. It is similar to `RANGE', except that only `VALUES IN'
     may be used to specify allowable values for each partition.

     `VALUES IN' is used with a list of values to be matched. For
     instance, you could create a partitioning scheme such as the
     following:

          CREATE TABLE client_firms (
              id   INT,
              name VARCHAR(35)
          )
          PARTITION BY LIST (id) (
              PARTITION r0 VALUES IN (1, 5, 9, 13, 17, 21),
              PARTITION r1 VALUES IN (2, 6, 10, 14, 18, 22),
              PARTITION r2 VALUES IN (3, 7, 11, 15, 19, 23),
              PARTITION r3 VALUES IN (4, 8, 12, 16, 20, 24)
          );

     When using list partitioning, you must define at least one
     partition using `VALUES IN'. You cannot use `VALUES LESS THAN'
     with `PARTITION BY LIST'.

     *Note*:

     Currently, the value list used with `VALUES IN' must consist of
     integer values only.

   * The number of partitions may optionally be specified with a
     `PARTITIONS NUM' clause, where NUM is the number of partitions. If
     both this clause _and_ any `PARTITION' clauses are used, NUM must
     be equal to the total number of any partitions that are declared
     using `PARTITION' clauses.

     *Note*:

     Whether or not you use a `PARTITIONS' clause in creating a table
     that is partitioned by `RANGE' or `LIST', you must still include
     at least one `PARTITION VALUES' clause in the table definition
     (see below).

   * A partition may optionally be divided into a number of
     subpartitions. This can be indicated by using the optional
     `SUBPARTITION BY' clause. Subpartitioning may be done by `HASH' or
     `KEY'.  Either of these may be `LINEAR'. These work in the same
     way as previously described for the equivalent partitioning types.
     (It is not possible to subpartition by `LIST' or `RANGE'.)

     The number of subpartitions can be indicated using the
     `SUBPARTITIONS' keyword followed by an integer value.

   * Rigorous checking of the value used in `PARTITIONS' or
     `SUBPARTITIONS' clauses is applied and this value must adhere to
     the following rules:

        * The value must be a positive, non-zero integer.

        * No leading zeroes are permitted.

        * The value must be an integer literal, and cannot not be an
          expression. For example, `PARTITIONS 0.2E+01' is not allowed,
          even though `0.2E+01' evaluates to `2'. (Bug#15890
          (http://bugs.mysql.com/15890))

*Note*:

The expression (EXPR) used in a `PARTITION BY' clause cannot refer to
any columns not in the table being created, and attempting to do so
causes the statement to fail with an error. (Bug#29444
(http://bugs.mysql.com/29444))

Each partition may be individually defined using a PARTITION_DEFINITION
clause. The individual parts making up this clause are as follows:

   * `PARTITION PARTITION_NAME': This specifies a logical name for the
     partition.

   * A `VALUES' clause: For range partitioning, each partition must
     include a `VALUES LESS THAN' clause; for list partitioning, you
     must specify a `VALUES IN' clause for each partition. This is used
     to determine which rows are to be stored in this partition. See
     the discussions of partitioning types in *Note partitioning::, for
     syntax examples.

   * An optional `COMMENT' clause may be used to specify a string that
     describes the partition. Example:

          COMMENT = 'Data for the years previous to 1999'

   * `DATA DIRECTORY' and `INDEX DIRECTORY' may be used to indicate the
     directory where, respectively, the data and indexes for this
     partition are to be stored. Both the `DATA_DIR' and the `INDEX_DIR'
     must be absolute system path names. Example:

          CREATE TABLE th (id INT, name VARCHAR(30), adate DATE)
          PARTITION BY LIST(YEAR(adate))
          (
            PARTITION p1999 VALUES IN (1995, 1999, 2003)
              DATA DIRECTORY = '`/var/appdata/95/data''
              INDEX DIRECTORY = '`/var/appdata/95/idx'',
            PARTITION p2000 VALUES IN (1996, 2000, 2004)
              DATA DIRECTORY = '`/var/appdata/96/data''
              INDEX DIRECTORY = '`/var/appdata/96/idx'',
            PARTITION p2001 VALUES IN (1997, 2001, 2005)
              DATA DIRECTORY = '`/var/appdata/97/data''
              INDEX DIRECTORY = '`/var/appdata/97/idx'',
            PARTITION p2000 VALUES IN (1998, 2002, 2006)
              DATA DIRECTORY = '`/var/appdata/98/data''
              INDEX DIRECTORY = '`/var/appdata/98/idx''
          );

     `DATA DIRECTORY' and `INDEX DIRECTORY' behave in the same way as
     in the *Note `CREATE TABLE': create-table. statement's
     TABLE_OPTION clause as used for `MyISAM' tables.

     One data directory and one index directory may be specified per
     partition. If left unspecified, the data and indexes are stored by
     default in the table's database directory.

     On Windows, the `DATA DIRECTORY' and `INDEX DIRECTORY' options are
     not supported for individual partitions or subpartitions.
     Beginning with MySQL 6.0.5, these options are ignored on Windows,
     except that a warning is generated. (Bug#30459
     (http://bugs.mysql.com/30459))

   * `MAX_ROWS' and `MIN_ROWS' may be used to specify, respectively,
     the maximum and minimum number of rows to be stored in the
     partition. The values for MAX_NUMBER_OF_ROWS and
     MIN_NUMBER_OF_ROWS must be positive integers. As with the
     table-level options with the same names, these act only as
     `suggestions' to the server and are not hard limits.

   * The optional `TABLESPACE' clause may be used to designate a
     tablespace for the partition. Used for `Falcon' only.

   * The partitioning handler accepts a `[STORAGE] ENGINE' option for
     both `PARTITION' and `SUBPARTITION'. Currently, the only way in
     which this can be used is to set all partitions or all
     subpartitions to the same storage engine, and an attempt to set
     different storage engines for partitions or subpartitions in the
     same table will give rise to the error `ERROR 1469 (HY000): The
     mix of handlers in the partitions is not allowed in this version
     of MySQL'. We expect to lift this restriction on partitioning in a
     future MySQL release.

   * The partition definition may optionally contain one or more
     SUBPARTITION_DEFINITION clauses.  Each of these consists at a
     minimum of the `SUBPARTITION NAME', where NAME is an identifier
     for the subpartition. Except for the replacement of the
     `PARTITION' keyword with `SUBPARTITION', the syntax for a
     subpartition definition is identical to that for a partition
     definition.

     Subpartitioning must be done by `HASH' or `KEY', and can be done
     only on `RANGE' or `LIST' partitions. See *Note
     partitioning-subpartitions::.

Partitions can be modified, merged, added to tables, and dropped from
tables. For basic information about the MySQL statements to accomplish
these tasks, see *Note alter-table::. For more detailed descriptions
and examples, see *Note partitioning-management::.

*Important*:

The original *Note `CREATE TABLE': create-table.  statement, including
all specifications and table options are stored by MySQL when the table
is created. The information is retained so that if you change storage
engines, collations or other settings using an *Note `ALTER TABLE':
alter-table. statement, the original table options specified are
retained. This allows you to change between `InnoDB' and `MyISAM' table
types even though the row formats supported by the two engines are
different.

Because the text of the original statement is retained, but due to the
way that certain values and options may be silently reconfigured (such
as the `ROW_FORMAT'), the active table definition (accessible through
*Note `DESCRIBE': describe. or with *Note `SHOW TABLE STATUS':
show-table-status.) and the table creation string (accessible through
*Note `SHOW CREATE TABLE': show-create-table.) will report different
values.

You can create one table from another by adding a *Note `SELECT':
select. statement at the end of the *Note `CREATE TABLE': create-table.
statement:

     CREATE TABLE NEW_TBL SELECT * FROM ORIG_TBL;

MySQL creates new columns for all elements in the *Note `SELECT':
select. For example:

     mysql> CREATE TABLE test (a INT NOT NULL AUTO_INCREMENT,
         ->        PRIMARY KEY (a), KEY(b))
         ->        ENGINE=MyISAM SELECT b,c FROM test2;

This creates a `MyISAM' table with three columns, `a', `b', and `c'.
Notice that the columns from the *Note `SELECT': select. statement are
appended to the right side of the table, not overlapped onto it. Take
the following example:

     mysql> SELECT * FROM foo;
     +---+
     | n |
     +---+
     | 1 |
     +---+

     mysql> CREATE TABLE bar (m INT) SELECT n FROM foo;
     Query OK, 1 row affected (0.02 sec)
     Records: 1  Duplicates: 0  Warnings: 0

     mysql> SELECT * FROM bar;
     +------+---+
     | m    | n |
     +------+---+
     | NULL | 1 |
     +------+---+
     1 row in set (0.00 sec)

For each row in table `foo', a row is inserted in `bar' with the values
from `foo' and default values for the new columns.

In a table resulting from `CREATE TABLE ...  SELECT', columns named
only in the *Note `CREATE TABLE': create-table. part come first.
Columns named in both parts or only in the *Note `SELECT': select. part
come after that. The data type of *Note `SELECT': select. columns can be
overridden by also specifying the column in the *Note `CREATE TABLE':
create-table. part.

If any errors occur while copying the data to the table, it is
automatically dropped and not created.

`CREATE TABLE ... SELECT' does not automatically create any indexes for
you. This is done intentionally to make the statement as flexible as
possible. If you want to have indexes in the created table, you should
specify these before the *Note `SELECT': select. statement:

     mysql> CREATE TABLE bar (UNIQUE (n)) SELECT n FROM foo;

Some conversion of data types might occur. For example, the
`AUTO_INCREMENT' attribute is not preserved, and *Note `VARCHAR': char.
columns can become *Note `CHAR': char. columns. Retrained attributes
are `NULL' (or `NOT NULL') and, for those columns that have them,
`CHARACTER SET', `COLLATION', `COMMENT', and the `DEFAULT' clause.

When creating a table with `CREATE ... SELECT', make sure to alias any
function calls or expressions in the query.  If you do not, the
`CREATE' statement might fail or result in undesirable column names.

     CREATE TABLE artists_and_works
       SELECT artist.name, COUNT(work.artist_id) AS number_of_works
       FROM artist LEFT JOIN work ON artist.id = work.artist_id
       GROUP BY artist.id;

You can also explicitly specify the data type for a generated column:

     CREATE TABLE foo (a TINYINT NOT NULL) SELECT b+1 AS a FROM bar;

Use `LIKE' to create an empty table based on the definition of another
table, including any column attributes and indexes defined in the
original table:

     CREATE TABLE NEW_TBL LIKE ORIG_TBL;

The copy is created using the same version of the table storage format
as the original table. The `SELECT' privilege is required on the
original table.

`LIKE' works only for base tables, not for views.

`CREATE TABLE ... LIKE' does not preserve any `DATA DIRECTORY' or `INDEX
DIRECTORY' table options that were specified for the original table, or
any foreign key definitions.

You can precede the *Note `SELECT': select. by `IGNORE' or *Note
`REPLACE': replace. to indicate how to handle rows that duplicate
unique key values. With `IGNORE', new rows that duplicate an existing
row on a unique key value are discarded. With *Note `REPLACE': replace,
new rows replace rows that have the same unique key value. If neither
`IGNORE' nor *Note `REPLACE': replace. is specified, duplicate unique
key values result in an error.

To ensure that the binary log can be used to re-create the original
tables, MySQL does not allow concurrent inserts during `CREATE TABLE
... SELECT'.


File: manual.info,  Node: silent-column-changes,  Prev: create-table,  Up: create-table

12.1.14.1 Silent Column Specification Changes
.............................................

In some cases, MySQL silently changes column specifications from those
given in a *Note `CREATE TABLE': create-table. or *Note `ALTER TABLE':
alter-table. statement. These might be changes to a data type, to
attributes associated with a data type, or to an index specification.

   * *Note `TIMESTAMP': datetime. columns are `NOT NULL' by default.

   * Columns that are part of a `PRIMARY KEY' are made `NOT NULL' even
     if not declared that way.

   * Trailing spaces are automatically deleted from *Note `ENUM': enum.
     and *Note `SET': set. member values when the table is created.

   * MySQL maps certain data types used by other SQL database vendors
     to MySQL types. See *Note other-vendor-data-types::.

   * If you include a `USING' clause to specify an index type that is
     not legal for a given storage engine, but there is another index
     type available that the engine can use without affecting query
     results, the engine uses the available type.

   * If strict SQL mode is not enabled, a *Note `VARCHAR': char. column
     with a length specification greater than 65535 is converted to
     *Note `TEXT': blob, and a *Note `VARBINARY': binary-varbinary.
     column with a length specification greater than 65535 is converted
     to *Note `BLOB': blob. Otherwise, an error occurs in either of
     these cases.

   * Specifying the `CHARACTER SET binary' attribute for a character
     data type causes the column to be created as the corresponding
     binary data type: *Note `CHAR': char. becomes *Note `BINARY':
     binary-varbinary, *Note `VARCHAR': char. becomes *Note
     `VARBINARY': binary-varbinary, and *Note `TEXT': blob. becomes
     *Note `BLOB': blob. For the *Note `ENUM': enum. and *Note `SET':
     set. data types, this does not occur; they are created as
     declared. Suppose that you specify a table using this definition:

          CREATE TABLE t
          (
            c1 VARCHAR(10) CHARACTER SET binary,
            c2 TEXT CHARACTER SET binary,
            c3 ENUM('a','b','c') CHARACTER SET binary
          );

     The resulting table has this definition:

          CREATE TABLE t
          (
            c1 VARBINARY(10),
            c2 BLOB,
            c3 ENUM('a','b','c') CHARACTER SET binary
          );

To see whether MySQL used a data type other than the one you specified,
issue a *Note `DESCRIBE': describe. or *Note `SHOW CREATE TABLE':
show-create-table. statement after creating or altering the table.

Certain other data type changes can occur if you compress a table using
*Note `myisampack': myisampack. See *Note compressed-format::.


File: manual.info,  Node: create-trigger,  Next: create-view,  Prev: create-table,  Up: sql-syntax-data-definition

12.1.15 `CREATE TRIGGER' Syntax
-------------------------------

     CREATE
         [DEFINER = { USER | CURRENT_USER }]
         TRIGGER TRIGGER_NAME TRIGGER_TIME TRIGGER_EVENT
         ON TBL_NAME FOR EACH ROW TRIGGER_STMT

This statement creates a new trigger. A trigger is a named database
object that is associated with a table, and that activates when a
particular event occurs for the table. The trigger becomes associated
with the table named TBL_NAME, which must refer to a permanent table.
You cannot associate a trigger with a `TEMPORARY' table or a view.

MySQL Enterprise

For expert advice on creating triggers subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Note `CREATE TRIGGER': create-trigger. requires the `TRIGGER'
privilege for the table associated with the trigger.

The `DEFINER' clause determines the security context to be used when
checking access privileges at trigger activation time.

TRIGGER_TIME is the trigger action time. It can be `BEFORE' or `AFTER'
to indicate that the trigger activates before or after each row to be
modified.

TRIGGER_EVENT indicates the kind of statement that activates the
trigger. The TRIGGER_EVENT can be one of the following:

   * *Note `INSERT': insert.: The trigger is activated whenever a new
     row is inserted into the table; for example, through *Note
     `INSERT': insert, *Note `LOAD DATA': load-data, and *Note
     `REPLACE': replace. statements.

   * *Note `UPDATE': update.: The trigger is activated whenever a row
     is modified; for example, through *Note `UPDATE': update.
     statements.

   * *Note `DELETE': delete.: The trigger is activated whenever a row
     is deleted from the table; for example, through *Note `DELETE':
     delete. and *Note `REPLACE': replace. statements. However, *Note
     `DROP TABLE': drop-table. and *Note `TRUNCATE': truncate.
     statements on the table do _not_ activate this trigger, because
     they do not use *Note `DELETE': delete.  Dropping a partition does
     not activate *Note `DELETE': delete. triggers, either. See *Note
     truncate::.

It is important to understand that the TRIGGER_EVENT does not represent
a literal type of SQL statement that activates the trigger so much as
it represents a type of table operation. For example, an *Note
`INSERT': insert. trigger is activated by not only *Note `INSERT':
insert. statements but also *Note `LOAD DATA': load-data. statements
because both statements insert rows into a table.

A potentially confusing example of this is the `INSERT INTO ... ON
DUPLICATE KEY UPDATE ...' syntax: a `BEFORE INSERT' trigger will
activate for every row, followed by either an `AFTER INSERT' trigger or
both the `BEFORE UPDATE' and `AFTER UPDATE' triggers, depending on
whether there was a duplicate key for the row.

There cannot be two triggers for a given table that have the same
trigger action time and event. For example, you cannot have two `BEFORE
UPDATE' triggers for a table. But you can have a `BEFORE UPDATE' and a
`BEFORE INSERT' trigger, or a `BEFORE UPDATE' and an `AFTER UPDATE'
trigger.

TRIGGER_STMT is the statement to execute when the trigger activates. If
you want to execute multiple statements, use the `BEGIN ... END'
compound statement construct. This also enables you to use the same
statements that are allowable within stored routines. See *Note
begin-end::. Some statements are not allowed in triggers; see *Note
stored-program-restrictions::.

MySQL stores the `sql_mode' system variable setting that is in effect
at the time a trigger is created, and always executes the trigger with
this setting in force, _regardless of the current server SQL mode_.

*Note*:

Currently, triggers are not activated by cascaded foreign key actions.
This limitation will be lifted as soon as possible.

In MySQL 6.0, you can write triggers containing direct references to
tables by name, such as the trigger named `testref' shown in this
example:

     CREATE TABLE test1(a1 INT);
     CREATE TABLE test2(a2 INT);
     CREATE TABLE test3(a3 INT NOT NULL AUTO_INCREMENT PRIMARY KEY);
     CREATE TABLE test4(
       a4 INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
       b4 INT DEFAULT 0
     );

     delimiter |

     CREATE TRIGGER testref BEFORE INSERT ON test1
       FOR EACH ROW BEGIN
         INSERT INTO test2 SET a2 = NEW.a1;
         DELETE FROM test3 WHERE a3 = NEW.a1;
         UPDATE test4 SET b4 = b4 + 1 WHERE a4 = NEW.a1;
       END;
     |

     delimiter ;

     INSERT INTO test3 (a3) VALUES
       (NULL), (NULL), (NULL), (NULL), (NULL),
       (NULL), (NULL), (NULL), (NULL), (NULL);

     INSERT INTO test4 (a4) VALUES
       (0), (0), (0), (0), (0), (0), (0), (0), (0), (0);

Suppose that you insert the following values into table `test1' as
shown here:

     mysql> INSERT INTO test1 VALUES
         -> (1), (3), (1), (7), (1), (8), (4), (4);
     Query OK, 8 rows affected (0.01 sec)
     Records: 8  Duplicates: 0  Warnings: 0

As a result, the data in the four tables will be as follows:

     mysql> SELECT * FROM test1;
     +------+
     | a1   |
     +------+
     |    1 |
     |    3 |
     |    1 |
     |    7 |
     |    1 |
     |    8 |
     |    4 |
     |    4 |
     +------+
     8 rows in set (0.00 sec)

     mysql> SELECT * FROM test2;
     +------+
     | a2   |
     +------+
     |    1 |
     |    3 |
     |    1 |
     |    7 |
     |    1 |
     |    8 |
     |    4 |
     |    4 |
     +------+
     8 rows in set (0.00 sec)

     mysql> SELECT * FROM test3;
     +----+
     | a3 |
     +----+
     |  2 |
     |  5 |
     |  6 |
     |  9 |
     | 10 |
     +----+
     5 rows in set (0.00 sec)

     mysql> SELECT * FROM test4;
     +----+------+
     | a4 | b4   |
     +----+------+
     |  1 |    3 |
     |  2 |    0 |
     |  3 |    1 |
     |  4 |    2 |
     |  5 |    0 |
     |  6 |    0 |
     |  7 |    1 |
     |  8 |    1 |
     |  9 |    0 |
     | 10 |    0 |
     +----+------+
     10 rows in set (0.00 sec)

You can refer to columns in the subject table (the table associated
with the trigger) by using the aliases `OLD' and `NEW'.  `OLD.COL_NAME'
refers to a column of an existing row before it is updated or deleted.
`NEW.COL_NAME' refers to the column of a new row to be inserted or an
existing row after it is updated.

The `DEFINER' clause specifies the MySQL account to be used when
checking access privileges at trigger activation time. If a USER value
is given, it should be a MySQL account in `'USER_NAME'@'HOST_NAME''
format (the same format used in the *Note `GRANT': grant. statement).
The USER_NAME and HOST_NAME values both are required. The definer can
also be given as `CURRENT_USER' or `CURRENT_USER()'. The default
`DEFINER' value is the user who executes the *Note `CREATE TRIGGER':
create-trigger. statement. (This is the same as `DEFINER =
CURRENT_USER'.)

If you specify the `DEFINER' clause, these rules determine the legal
`DEFINER' user values:

   * If you do not have the `SUPER' privilege, the only legal USER
     value is your own account, either specified literally or by using
     `CURRENT_USER'. You cannot set the definer to some other account.

   * If you have the `SUPER' privilege, you can specify any
     syntactically legal account name. If the account does not actually
     exist, a warning is generated.

   * Although it is possible to create triggers with a non-existent
     `DEFINER' value, it is not a good idea for such triggers to be
     activated until the definer actually does exist. Otherwise, the
     behavior with respect to privilege checking is undefined.

MySQL takes the `DEFINER' user into account when checking trigger
privileges, as follows:

   * At *Note `CREATE TRIGGER': create-trigger. time, the user who
     issues the statement must have the `TRIGGER' privilege.

   * At trigger activation time, privileges are checked against the
     `DEFINER' user. This user must have these privileges:

        * The `TRIGGER' privilege.

        * The `SELECT' privilege for the subject table if references to
          table columns occur via `OLD.COL_NAME' or `NEW.COL_NAME' in
          the trigger definition.

        * The `UPDATE' privilege for the subject table if table columns
          are targets of `SET NEW.COL_NAME = VALUE' assignments in the
          trigger definition.

        * Whatever other privileges normally are required for the
          statements executed by the trigger.

Within a trigger, the `CURRENT_USER()' function returns the account
used to check privileges at trigger activation time. This is the
`DEFINER' user, not the user whose actions caused the trigger to be
activated. For information about user auditing within triggers, see
*Note account-activity-auditing::.

If you use *Note `LOCK TABLES': lock-tables. to lock a table that has
triggers, the tables used within the trigger are also locked, as
described in *Note lock-tables-and-triggers::.


File: manual.info,  Node: create-view,  Next: drop-database,  Prev: create-trigger,  Up: sql-syntax-data-definition

12.1.16 `CREATE VIEW' Syntax
----------------------------

     CREATE
         [OR REPLACE]
         [ALGORITHM = {UNDEFINED | MERGE | TEMPTABLE}]
         [DEFINER = { USER | CURRENT_USER }]
         [SQL SECURITY { DEFINER | INVOKER }]
         VIEW VIEW_NAME [(COLUMN_LIST)]
         AS SELECT_STATEMENT
         [WITH [CASCADED | LOCAL] CHECK OPTION]

The *Note `CREATE VIEW': create-view. statement creates a new view, or
replaces an existing one if the `OR REPLACE' clause is given. If the
view does not exist, `CREATE OR REPLACE VIEW' is the same as *Note
`CREATE VIEW': create-view. If the view does exist, `CREATE OR REPLACE
VIEW' is the same as *Note `ALTER VIEW': alter-view.

The SELECT_STATEMENT is a *Note `SELECT': select. statement that
provides the definition of the view. (When you select from the view,
you select in effect using the *Note `SELECT': select.  statement.)
SELECT_STATEMENT can select from base tables or other views.

The view definition is `frozen' at creation time, so changes to the
underlying tables afterward do not affect the view definition. For
example, if a view is defined as `SELECT *' on a table, new columns
added to the table later do not become part of the view.

The `ALGORITHM' clause affects how MySQL processes the view. The
`DEFINER' and `SQL SECURITY' clauses specify the security context to be
used when checking access privileges at view invocation time. The `WITH
CHECK OPTION' clause can be given to constrain inserts or updates to
rows in tables referenced by the view. These clauses are described
later in this section.

The *Note `CREATE VIEW': create-view. statement requires the `CREATE
VIEW' privilege for the view, and some privilege for each column
selected by the *Note `SELECT': select. statement. For columns used
elsewhere in the *Note `SELECT': select. statement you must have the
`SELECT' privilege.  If the `OR REPLACE' clause is present, you must
also have the `DROP' privilege for the view.

A view belongs to a database. By default, a new view is created in the
default database. To create the view explicitly in a given database,
specify the name as DB_NAME.VIEW_NAME when you create it.

     mysql> CREATE VIEW test.v AS SELECT * FROM t;

Base tables and views share the same namespace within a database, so a
database cannot contain a base table and a view that have the same name.

Views must have unique column names with no duplicates, just like base
tables. By default, the names of the columns retrieved by the *Note
`SELECT': select. statement are used for the view column names. To
define explicit names for the view columns, the optional COLUMN_LIST
clause can be given as a list of comma-separated identifiers. The
number of names in COLUMN_LIST must be the same as the number of
columns retrieved by the *Note `SELECT': select. statement.

*Note*:

Prior to MySQL 6.0.8, When you modify an existing view, the current
view definition is backed up and saved. It is stored in that table's
database directory, in a subdirectory named `arc'. The backup file for
a view `v' is named `v.frm-00001'.  If you alter the view again, the
next backup is named `v.frm-00002'. The three latest view backup
definitions are stored.

Backed up view definitions are not preserved by *Note `mysqldump':
mysqldump, or any other such programs, but you can retain them using a
file copy operation. However, they are not needed for anything but to
provide you with a backup of your previous view definition.

It is safe to remove these backup definitions, but only while *Note
`mysqld': mysqld. is not running. If you delete the `arc' subdirectory
or its files while *Note `mysqld': mysqld. is running, you will receive
an error the next time you try to alter the view:

     mysql> ALTER VIEW v AS SELECT * FROM t;
     ERROR 6 (HY000): Error on delete of '.\test\arc/v.frm-0004' (Errcode:
     2)

Columns retrieved by the *Note `SELECT': select.  statement can be
simple references to table columns. They can also be expressions that
use functions, constant values, operators, and so forth.

Unqualified table or view names in the *Note `SELECT': select.
statement are interpreted with respect to the default database. A view
can refer to tables or views in other databases by qualifying the table
or view name with the proper database name.

A view can be created from many kinds of *Note `SELECT': select.
statements. It can refer to base tables or other views. It can use
joins, *Note `UNION': union, and subqueries. The *Note `SELECT':
select. need not even refer to any tables. The following example
defines a view that selects two columns from another table, as well as
an expression calculated from those columns:

     mysql> CREATE TABLE t (qty INT, price INT);
     mysql> INSERT INTO t VALUES(3, 50);
     mysql> CREATE VIEW v AS SELECT qty, price, qty*price AS value FROM t;
     mysql> SELECT * FROM v;
     +------+-------+-------+
     | qty  | price | value |
     +------+-------+-------+
     |    3 |    50 |   150 |
     +------+-------+-------+

A view definition is subject to the following restrictions:

   * The *Note `SELECT': select. statement cannot contain a subquery in
     the `FROM' clause.

   * The *Note `SELECT': select. statement cannot refer to system or
     user variables.

   * Within a stored program, the definition cannot refer to program
     parameters or local variables.

   * The *Note `SELECT': select. statement cannot refer to prepared
     statement parameters.

   * Any table or view referred to in the definition must exist.
     However, after a view has been created, it is possible to drop a
     table or view that the definition refers to. In this case, use of
     the view results in an error. To check a view definition for
     problems of this kind, use the *Note `CHECK TABLE': check-table.
     statement.

   * The definition cannot refer to a `TEMPORARY' table, and you cannot
     create a `TEMPORARY' view.

   * Any tables named in the view definition must exist at definition
     time.

   * You cannot associate a trigger with a view.

   * As of MySQL 6.0.4, aliases for column names in the *Note `SELECT':
     select. statement are checked against the maximum column length of
     64 characters (not the maximum alias length of 256 characters).

`ORDER BY' is allowed in a view definition, but it is ignored if you
select from a view using a statement that has its own `ORDER BY'.

For other options or clauses in the definition, they are added to the
options or clauses of the statement that references the view, but the
effect is undefined. For example, if a view definition includes a
`LIMIT' clause, and you select from the view using a statement that has
its own `LIMIT' clause, it is undefined which limit applies. This same
principle applies to options such as `ALL', `DISTINCT', or
`SQL_SMALL_RESULT' that follow the *Note `SELECT': select. keyword, and
to clauses such as `INTO', `FOR UPDATE', `LOCK IN SHARE MODE', and
`PROCEDURE'.

If you create a view and then change the query processing environment
by changing system variables, that may affect the results that you get
from the view:

     mysql> CREATE VIEW v (mycol) AS SELECT 'abc';
     Query OK, 0 rows affected (0.01 sec)

     mysql> SET sql_mode = '';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT "mycol" FROM v;
     +-------+
     | mycol |
     +-------+
     | mycol |
     +-------+
     1 row in set (0.01 sec)

     mysql> SET sql_mode = 'ANSI_QUOTES';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT "mycol" FROM v;
     +-------+
     | mycol |
     +-------+
     | abc   |
     +-------+
     1 row in set (0.00 sec)

The `DEFINER' and `SQL SECURITY' clauses determine which MySQL account
to use when checking access privileges for the view when a statement is
executed that references the view. The legal `SQL SECURITY'
characteristic values are `DEFINER' and `INVOKER'. These indicate that
the required privileges must be held by the user who defined or invoked
the view, respectively. The default `SQL SECURITY' value is `DEFINER'.

If a USER value is given for the `DEFINER' clause, it should be a MySQL
account in `'USER_NAME'@'HOST_NAME'' format (the same format used in the
*Note `GRANT': grant. statement). The USER_NAME and HOST_NAME values
both are required. The definer can also be given as `CURRENT_USER' or
`CURRENT_USER()'. The default `DEFINER' value is the user who executes
the *Note `CREATE VIEW': create-view. statement. This is the same as
specifying `DEFINER = CURRENT_USER' explicitly.

If you specify the `DEFINER' clause, these rules determine the legal
`DEFINER' user values:

   * If you do not have the `SUPER' privilege, the only legal USER
     value is your own account, either specified literally or by using
     `CURRENT_USER'. You cannot set the definer to some other account.

   * If you have the `SUPER' privilege, you can specify any
     syntactically legal account name. If the account does not actually
     exist, a warning is generated.

   * If the `SQL SECURITY' value is `DEFINER' but the definer account
     does not exist when the view is referenced, an error occurs.

Within a view definition, `CURRENT_USER' returns the view's `DEFINER'
value by default. For views defined with the `SQL SECURITY INVOKER'
characteristic, `CURRENT_USER' returns the account for the view's
invoker. For information about user auditing within views, see *Note
account-activity-auditing::.

Within a stored routine that is defined with the `SQL SECURITY DEFINER'
characteristic, `CURRENT_USER' returns the routine's `DEFINER' value.
This also affects a view defined within such a program, if the view
definition contains a `DEFINER' value of `CURRENT_USER'.

View privileges are checked like this:

   * At view definition time, the view creator must have the privileges
     needed to use the top-level objects accessed by the view. For
     example, if the view definition refers to table columns, the
     creator must have privileges for the columns, as described
     previously. If the definition refers to a stored function, only
     the privileges needed to invoke the function can be checked. The
     privileges required when the function runs can be checked only as
     it executes: For different invocations of the function, different
     execution paths within the function might be taken.

   * When a view is referenced, privileges for objects accessed by the
     view are checked against the privileges held by the view creator
     or invoker, depending on whether the `SQL SECURITY' characteristic
     is `DEFINER' or `INVOKER', respectively.

   * If reference to a view causes execution of a stored function,
     privilege checking for statements executed within the function
     depend on whether the function is defined with a `SQL SECURITY'
     characteristic of `DEFINER' or `INVOKER'. If the security
     characteristic is `DEFINER', the function runs with the privileges
     of its creator. If the characteristic is `INVOKER', the function
     runs with the privileges determined by the view's `SQL SECURITY'
     characteristic.

Example: A view might depend on a stored function, and that function
might invoke other stored routines. For example, the following view
invokes a stored function `f()':

     CREATE VIEW v AS SELECT * FROM t WHERE t.id = f(t.name);

Suppose that `f()' contains a statement such as this:

     IF name IS NULL then
       CALL p1();
     ELSE
       CALL p2();
     END IF;

The privileges required for executing statements within `f()' need to
be checked when `f()' executes. This might mean that privileges are
needed for `p1()' or `p2()', depending on the execution path within
`f()'.  Those privileges must be checked at runtime, and the user who
must possess the privileges is determined by the `SQL SECURITY' values
of the view `v' and the function `f()'.

The `DEFINER' and `SQL SECURITY' clauses for views are extensions to
standard SQL. In standard SQL, views are handled using the rules for
`SQL SECURITY INVOKER'.

If you invoke a view that was created before MySQL 5.0.13/5.1.2, it is
treated as though it was created with a `SQL SECURITY DEFINER' clause
and with a `DEFINER' value that is the same as your account.  However,
because the actual definer is unknown, MySQL issues a warning. To make
the warning go away, it is sufficient to re-create the view so that the
view definition includes a `DEFINER' clause.

The optional `ALGORITHM' clause is a MySQL extension to standard SQL.
It affects how MySQL processes the view. `ALGORITHM' takes three values:
`MERGE', `TEMPTABLE', or `UNDEFINED'. The default algorithm is
`UNDEFINED' if no `ALGORITHM' clause is present. For more information,
see *Note view-algorithms::.

Some views are updatable. That is, you can use them in statements such
as *Note `UPDATE': update, *Note `DELETE': delete, or *Note `INSERT':
insert. to update the contents of the underlying table. For a view to
be updatable, there must be a one-to-one relationship between the rows
in the view and the rows in the underlying table. There are also
certain other constructs that make a view non-updatable.

The `WITH CHECK OPTION' clause can be given for an updatable view to
prevent inserts or updates to rows except those for which the `WHERE'
clause in the SELECT_STATEMENT is true.

In a `WITH CHECK OPTION' clause for an updatable view, the `LOCAL' and
`CASCADED' keywords determine the scope of check testing when the view
is defined in terms of another view. The `LOCAL' keyword restricts the
`CHECK OPTION' only to the view being defined. `CASCADED' causes the
checks for underlying views to be evaluated as well. When neither
keyword is given, the default is `CASCADED'.

For more information about updatable views and the `WITH CHECK OPTION'
clause, see *Note view-updatability::.


File: manual.info,  Node: drop-database,  Next: drop-event,  Prev: create-view,  Up: sql-syntax-data-definition

12.1.17 `DROP DATABASE' Syntax
------------------------------

     DROP {DATABASE | SCHEMA} [IF EXISTS] DB_NAME

*Note `DROP DATABASE': drop-database. drops all tables in the database
and deletes the database. Be _very_ careful with this statement! To use
*Note `DROP DATABASE': drop-database, you need the `DROP' privilege on
the database.  *Note `DROP SCHEMA': drop-database. is a synonym for
*Note `DROP DATABASE': drop-database.

*Important*:

When a database is dropped, user privileges on the database are _not_
automatically dropped. See *Note grant::.

`IF EXISTS' is used to prevent an error from occurring if the database
does not exist.

If you use *Note `DROP DATABASE': drop-database. on a symbolically
linked database, both the link and the original database are deleted.

*Note `DROP DATABASE': drop-database. returns the number of tables that
were removed. This corresponds to the number of `.frm' files removed.

The *Note `DROP DATABASE': drop-database. statement removes from the
given database directory those files and directories that MySQL itself
may create during normal operation:

   * All files with the following extensions.

     `.BAK'  `.DAT'  `.HSH'  `.MRG'
     `.MYD'  `.MYI'  `.TRG'  `.TRN'
     `.db'   `.frm'  `.ibd'  `.ndb'
     `.par'                  

   * The `db.opt' file, if it exists.

If other files or directories remain in the database directory after
MySQL removes those just listed, the database directory cannot be
removed. In this case, you must remove any remaining files or
directories manually and issue the *Note `DROP DATABASE':
drop-database. statement again.

You can also drop databases with *Note `mysqladmin': mysqladmin.  See
*Note mysqladmin::.


File: manual.info,  Node: drop-event,  Next: drop-function,  Prev: drop-database,  Up: sql-syntax-data-definition

12.1.18 `DROP EVENT' Syntax
---------------------------

     DROP EVENT [IF EXISTS] EVENT_NAME

This statement drops the event named EVENT_NAME. The event immediately
ceases being active, and is deleted completely from the server.

If the event does not exist, the error `ERROR 1517 (HY000): Unknown
event 'EVENT_NAME'' results. You can override this and cause the
statement to generate a warning for non-existent events instead using
`IF EXISTS'.

This statement requires the `EVENT' privilege for the schema to which
the event to be dropped belongs.


File: manual.info,  Node: drop-function,  Next: drop-index,  Prev: drop-event,  Up: sql-syntax-data-definition

12.1.19 `DROP FUNCTION' Syntax
------------------------------

The *Note `DROP FUNCTION': drop-function. statement is used to drop
stored functions and user-defined functions (UDFs):

   * For information about dropping stored functions, see *Note
     drop-procedure::.

   * For information about dropping user-defined functions, see *Note
     drop-function-udf::.


File: manual.info,  Node: drop-index,  Next: drop-procedure,  Prev: drop-function,  Up: sql-syntax-data-definition

12.1.20 `DROP INDEX' Syntax
---------------------------

     DROP INDEX INDEX_NAME ON TBL_NAME

*Note `DROP INDEX': drop-index. drops the index named INDEX_NAME from
the table TBL_NAME. This statement is mapped to an *Note `ALTER TABLE':
alter-table. statement to drop the index. See *Note alter-table::.

Indexes on variable-width columns are dropped online; that is, dropping
the indexes does not require any copying of the table.  This is done
automatically by the server whenever it determines that it is possible
to do so; you do not have to use any special SQL syntax or server
options to cause it to happen.

In standard MySQL 6.0 releases, it is not possible to override the
server when it determines that an index is to be dropped online. For
more information, see *Note alter-table::.


File: manual.info,  Node: drop-procedure,  Next: drop-server,  Prev: drop-index,  Up: sql-syntax-data-definition

12.1.21 `DROP PROCEDURE' and `DROP FUNCTION' Syntax
---------------------------------------------------

     DROP {PROCEDURE | FUNCTION} [IF EXISTS] SP_NAME

This statement is used to drop a stored procedure or function.  That
is, the specified routine is removed from the server. You must have the
`ALTER ROUTINE' privilege for the routine. (That privilege is granted
automatically to the routine creator.)

The `IF EXISTS' clause is a MySQL extension. It prevents an error from
occurring if the procedure or function does not exist. A warning is
produced that can be viewed with *Note `SHOW WARNINGS': show-warnings.

Prior to MySQL 6.0.10, `DROP PROCEDURE IF EXISTS' and `DROP FUNCTION IF
EXISTS' were not written to the binary log if the stored procedure or
function named in the `DROP' statement did not exist on the master.
(Bug#13684 (http://bugs.mysql.com/13684))

*Note `DROP FUNCTION': drop-function. is also used to drop user-defined
functions (see *Note drop-function-udf::).


File: manual.info,  Node: drop-server,  Next: drop-table,  Prev: drop-procedure,  Up: sql-syntax-data-definition

12.1.22 `DROP SERVER' Syntax
----------------------------

     DROP SERVER [ IF EXISTS ] SERVER_NAME

Drops the server definition for the server named `SERVER_NAME'. The
corresponding row within the `mysql.servers' table will be deleted.
This statement requires the `SUPER' privilege.

Dropping a server for a table does not affect any `FEDERATED' tables
that used this connection information when they were created. See *Note
create-server::.

*Note `DROP SERVER': drop-server. does not cause an automatic commit.


File: manual.info,  Node: drop-table,  Next: drop-trigger,  Prev: drop-server,  Up: sql-syntax-data-definition

12.1.23 `DROP TABLE' Syntax
---------------------------

     DROP [TEMPORARY] TABLE [IF EXISTS]
         TBL_NAME [, TBL_NAME] ...
         [RESTRICT | CASCADE]

*Note `DROP TABLE': drop-table. removes one or more tables. You must
have the `DROP' privilege for each table. All table data and the table
definition are _removed_, so _be careful_ with this statement! If any
of the tables named in the argument list do not exist, MySQL returns an
error indicating by name which non-existing tables it was unable to
drop, but it also drops all of the tables in the list that do exist.

*Important*:

When a table is dropped, user privileges on the table are _not_
automatically dropped. See *Note grant::.

Note that for a partitioned table, *Note `DROP TABLE': drop-table.
permanently removes the table definition, all of its partitions, and
all of the data which was stored in those partitions. It also removes
the partitioning definition (`.par') file associated with the dropped
table.

Use `IF EXISTS' to prevent an error from occurring for tables that do
not exist. A `NOTE' is generated for each non-existent table when using
`IF EXISTS'. See *Note show-warnings::.

`RESTRICT' and `CASCADE' are allowed to make porting easier. In MySQL
6.0, they do nothing.

*Note*:

*Note `DROP TABLE': drop-table. automatically commits the current
active transaction, unless you use the `TEMPORARY' keyword.

The `TEMPORARY' keyword has the following effects:

   * The statement drops only `TEMPORARY' tables.

   * The statement does not end an ongoing transaction.

   * No access rights are checked. (A `TEMPORARY' table is visible only
     to the session that created it, so no check is necessary.)

Using `TEMPORARY' is a good way to ensure that you do not accidentally
drop a non-`TEMPORARY' table.

As of MySQL 6.0.3, *Note `DROP TABLE': drop-table. is allowed only if
you have acquired a `WRITE' lock with *Note `LOCK TABLES': lock-tables,
or if you hold no locks, or if the table is a `TEMPORARY' table.
(Previously, if other tables were locked, you could drop a table with a
read lock or no lock, which could lead to deadlocks between sessions.
The current stricter behavior means that some usage scenarios will fail
when previously they did not.)


File: manual.info,  Node: drop-trigger,  Next: drop-view,  Prev: drop-table,  Up: sql-syntax-data-definition

12.1.24 `DROP TRIGGER' Syntax
-----------------------------

     DROP TRIGGER [IF EXISTS] [SCHEMA_NAME.]TRIGGER_NAME

This statement drops a trigger. The schema (database) name is optional.
If the schema is omitted, the trigger is dropped from the default
schema. *Note `DROP TRIGGER': drop-trigger.  was added in MySQL 5.0.2.
Its use requires the `TRIGGER' privilege for the table associated with
the trigger.

Use `IF EXISTS' to prevent an error from occurring for a trigger that
does not exist. A `NOTE' is generated for a non-existent trigger when
using `IF EXISTS'. See *Note show-warnings::.

Triggers for a table are also dropped if you drop the table.


File: manual.info,  Node: drop-view,  Next: rename-table,  Prev: drop-trigger,  Up: sql-syntax-data-definition

12.1.25 `DROP VIEW' Syntax
--------------------------

     DROP VIEW [IF EXISTS]
         VIEW_NAME [, VIEW_NAME] ...
         [RESTRICT | CASCADE]

*Note `DROP VIEW': drop-view. removes one or more views. You must have
the `DROP' privilege for each view. If any of the views named in the
argument list do not exist, MySQL returns an error indicating by name
which non-existing views it was unable to drop, but it also drops all of
the views in the list that do exist.

The `IF EXISTS' clause prevents an error from occurring for views that
don't exist. When this clause is given, a `NOTE' is generated for each
non-existent view.  See *Note show-warnings::.

`RESTRICT' and `CASCADE', if given, are parsed and ignored.


File: manual.info,  Node: rename-table,  Prev: drop-view,  Up: sql-syntax-data-definition

12.1.26 `RENAME TABLE' Syntax
-----------------------------

     RENAME TABLE TBL_NAME TO NEW_TBL_NAME
         [, TBL_NAME2 TO NEW_TBL_NAME2] ...

This statement renames one or more tables.

The rename operation is done atomically, which means that no other
session can access any of the tables while the rename is running.  For
example, if you have an existing table `old_table', you can create
another table `new_table' that has the same structure but is empty, and
then replace the existing table with the empty one as follows (assuming
that `backup_table' does not already exist):

     CREATE TABLE new_table (...);
     RENAME TABLE old_table TO backup_table, new_table TO old_table;

If the statement renames more than one table, renaming operations are
done from left to right. If you want to swap two table names, you can
do so like this (assuming that `tmp_table' does not already exist):

     RENAME TABLE old_table TO tmp_table,
                  new_table TO old_table,
                  tmp_table TO new_table;

As long as two databases are on the same file system, you can use *Note
`RENAME TABLE': rename-table. to move a table from one database to
another:

     RENAME TABLE CURRENT_DB.TBL_NAME TO OTHER_DB.TBL_NAME;

If there are any triggers associated with a table which is moved to a
different database using *Note `RENAME TABLE': rename-table, then the
statement fails with the error `Trigger in wrong schema'.

*Note `RENAME TABLE': rename-table. also works for views, as long as
you do not try to rename a view into a different database.

Any privileges granted specifically for the renamed table or view are
not migrated to the new name. They must be changed manually.

When you execute `RENAME', you cannot have any locked tables or active
transactions. You must also have the `ALTER' and `DROP' privileges on
the original table, and the `CREATE' and `INSERT' privileges on the new
table.

If MySQL encounters any errors in a multiple-table rename, it does a
reverse rename for all renamed tables to return everything to its
original state.

You cannot use `RENAME' to rename a `TEMPORARY' table. However, you can
use *Note `ALTER TABLE': alter-table. instead:

     mysql> ALTER TABLE orig_name RENAME new_name;


File: manual.info,  Node: sql-syntax-data-manipulation,  Next: sql-syntax-utility,  Prev: sql-syntax-data-definition,  Up: sql-syntax

12.2 Data Manipulation Statements
=================================

* Menu:

* call::                         `CALL' Syntax
* delete::                       `DELETE' Syntax
* do::                           `DO' Syntax
* handler::                      `HANDLER' Syntax
* insert::                       `INSERT' Syntax
* load-data::                    `LOAD DATA INFILE' Syntax
* load-xml::                     `LOAD XML' Syntax
* replace::                      `REPLACE' Syntax
* select::                       `SELECT' Syntax
* subqueries::                   Subquery Syntax
* truncate::                     `TRUNCATE' Syntax
* update::                       `UPDATE' Syntax


File: manual.info,  Node: call,  Next: delete,  Prev: sql-syntax-data-manipulation,  Up: sql-syntax-data-manipulation

12.2.1 `CALL' Syntax
--------------------

     CALL SP_NAME([PARAMETER[,...]])
     CALL SP_NAME[()]

The *Note `CALL': call. statement invokes a stored procedure that was
defined previously with *Note `CREATE PROCEDURE': create-procedure.

Stored procedures that take no arguments can be invoked without
parentheses. That is, `CALL p()' and `CALL p' are equivalent.

*Note `CALL': call. can pass back values to its caller using parameters
that are declared as `OUT' or `INOUT' parameters.  When the procedure
returns, a client program can also obtain the number of rows affected
for the final statement executed within the routine: At the SQL level,
call the `ROW_COUNT()' function; from the C API, call the *Note
`mysql_affected_rows()': mysql-affected-rows. function.

To get back a value from a procedure using an `OUT' or `INOUT'
parameter, pass the parameter by means of a user variable, and then
check the value of the variable after the procedure returns. (If you are
calling the procedure from within another stored procedure or function,
you can also pass a routine parameter or local routine variable as an
`IN' or `INOUT' parameter.) For an `INOUT' parameter, initialize its
value before passing it to the procedure. The following procedure has
an `OUT' parameter that the procedure sets to the current server
version, and an `INOUT' value that the procedure increments by one from
its current value:

     CREATE PROCEDURE p (OUT ver_param VARCHAR(25), INOUT incr_param INT)
     BEGIN
       # Set value of OUT parameter
       SELECT VERSION() INTO ver_param;
       # Increment value of INOUT parameter
       SET incr_param = incr_param + 1;
     END;

Before calling the procedure, initialize the variable to be passed as
the `INOUT' parameter. After calling the procedure, the values of the
two variables will have been set or modified:

     mysql> SET @increment = 10;
     mysql> CALL p(@version, @increment);
     mysql> SELECT @version, @increment;
     +------------------+------------+
     | @version         | @increment |
     +------------------+------------+
     | 6.0.10-alpha-log | 11         |
     +------------------+------------+

In prepared *Note `CALL': call. statements used with *Note `PREPARE':
prepare. and *Note `EXECUTE': execute, placeholders can be used for
`IN' parameters. For `OUT' and `INOUT' parameters, placeholder support
is available only as of MySQL 6.0.8. These types of parameters can be
used as follows:

     mysql> SET @increment = 10;
     mysql> PREPARE s FROM 'CALL p(?, ?)';
     mysql> EXECUTE s USING @version, @increment;
     mysql> SELECT @version, @increment;
     +------------------+------------+
     | @version         | @increment |
     +------------------+------------+
     | 6.0.10-alpha-log | 11         |
     +------------------+------------+

Before MySQL 6.0.8, placeholder support is not available for `OUT' or
`INOUT' parameters. To work around this limitation for `OUT' and
`INOUT' parameters, forego the use of placeholders; instead, refer to
user variables in the *Note `CALL': call. statement itself and do not
specify them in the *Note `EXECUTE': execute.  statement:

     mysql> SET @increment = 10;
     mysql> PREPARE s FROM 'CALL p(@version, @increment)';
     mysql> EXECUTE s;
     mysql> SELECT @version, @increment;
     +-----------------+------------+
     | @version        | @increment |
     +-----------------+------------+
     | 6.0.7-alpha-log | 11         |
     +-----------------+------------+

To write C programs that use the *Note `CALL': call. SQL statement to
execute stored procedures that produce result sets, the
`CLIENT_MULTI_RESULTS' flag must be enabled. This is because each *Note
`CALL': call. returns a result to indicate the call status, in addition
to any result sets that might be returned by statements executed within
the procedure. `CLIENT_MULTI_RESULTS' must also be enabled if *Note
`CALL': call. is used to execute any stored procedure that contains
prepared statements. It cannot be determined when such a procedure is
loaded whether those statements will produce result sets, so it is
necessary to assume that they will.

`CLIENT_MULTI_RESULTS' can be enabled when you call *Note
`mysql_real_connect()': mysql-real-connect, either explicitly by
passing the `CLIENT_MULTI_RESULTS' flag itself, or implicitly by passing
`CLIENT_MULTI_STATEMENTS' (which also enables `CLIENT_MULTI_RESULTS').
As of MySQL 6.0.8, `CLIENT_MULTI_RESULTS' is enabled by default.

To process the result of a *Note `CALL': call.  statement executed via
*Note `mysql_query()': mysql-query. or *Note `mysql_real_query()':
mysql-real-query, use a loop that calls *Note `mysql_next_result()':
mysql-next-result. to determine whether there are more results. For an
example, see *Note c-api-multiple-queries::.

For programs written in a language that provides a MySQL interface,
there is no native method prior to MySQL 6.0.8 for directly retrieving
the results of `OUT' or `INOUT' parameters from *Note `CALL': call.
statements. To get the parameter values, pass user-defined variables to
the procedure in the *Note `CALL': call. statement and then execute a
*Note `SELECT': select. statement to produce a result set containing
the variable values. To handle an `INOUT' parameter, execute a
statement prior to the *Note `CALL': call. that sets the corresponding
user variable to the value to be passed to the procedure.

The following example illustrates the technique (without error
checking) for the stored procedure `p' described earlier that has an
`OUT' parameter and an `INOUT' parameter:

     mysql_query(mysql, "SET @increment = 10");
     mysql_query(mysql, "CALL p(@version, @increment)");
     mysql_query(mysql, "SELECT @version, @increment");
     result = mysql_store_result(mysql);
     row = mysql_fetch_row(result);
     mysql_free_result(result);

After the preceding code executes, `row[0]' and `row[1]' contain the
values of `@version' and `@increment', respectively.

As of MySQL 6.0.8, C programs can use the prepared-statement interface
to execute *Note `CALL': call.  statements and access `OUT' and `INOUT'
parameters. This is done by processing the result of a *Note `CALL':
call. statement using a loop that calls *Note
`mysql_stmt_next_result()': mysql-stmt-next-result. to determine
whether there are more results. For an example, see *Note
c-api-prepared-call-statements::. Languages that provide a MySQL
interface can use prepared *Note `CALL': call. statements to directly
retrieve `OUT' and `INOUT' procedure parameters.


File: manual.info,  Node: delete,  Next: do,  Prev: call,  Up: sql-syntax-data-manipulation

12.2.2 `DELETE' Syntax
----------------------

Single-table syntax:

     DELETE [LOW_PRIORITY] [QUICK] [IGNORE] FROM TBL_NAME
         [WHERE WHERE_CONDITION]
         [ORDER BY ...]
         [LIMIT ROW_COUNT]

Multiple-table syntax:

     DELETE [LOW_PRIORITY] [QUICK] [IGNORE]
         TBL_NAME[.*] [, TBL_NAME[.*]] ...
         FROM TABLE_REFERENCES
         [WHERE WHERE_CONDITION]

Or:

     DELETE [LOW_PRIORITY] [QUICK] [IGNORE]
         FROM TBL_NAME[.*] [, TBL_NAME[.*]] ...
         USING TABLE_REFERENCES
         [WHERE WHERE_CONDITION]

For the single-table syntax, the *Note `DELETE': delete. statement
deletes rows from TBL_NAME and returns a count of the number of deleted
rows. This count can be obtained by calling the `ROW_COUNT()' function
(see *Note information-functions::). The `WHERE' clause, if given,
specifies the conditions that identify which rows to delete. With no
`WHERE' clause, all rows are deleted. If the `ORDER BY' clause is
specified, the rows are deleted in the order that is specified. The
`LIMIT' clause places a limit on the number of rows that can be deleted.

For the multiple-table syntax, *Note `DELETE': delete. deletes from each
TBL_NAME the rows that satisfy the conditions. In this case, `ORDER BY'
and `LIMIT' cannot be used.

WHERE_CONDITION is an expression that evaluates to true for each row to
be deleted. It is specified as described in *Note select::.

Currently, you cannot delete from a table and select from the same
table in a subquery.

As stated, a *Note `DELETE': delete. statement with no `WHERE' clause
deletes all rows. A faster way to do this, when you do not need to know
the number of deleted rows, is to use *Note `TRUNCATE TABLE': truncate.
However, within a transaction or if you have a lock on the table, *Note
`TRUNCATE TABLE': truncate.  cannot be used whereas *Note `DELETE':
delete. can.  See *Note truncate::, and *Note lock-tables::.

If you delete the row containing the maximum value for an
`AUTO_INCREMENT' column, the value is not reused for a `MyISAM' or
`InnoDB' table. If you delete all rows in the table with `DELETE FROM
TBL_NAME' (without a `WHERE' clause) in `autocommit' mode, the sequence
starts over for all storage engines except `InnoDB' and `MyISAM'. There
are some exceptions to this behavior for `InnoDB' tables, as discussed
in *Note innodb-auto-increment-handling::.

For `MyISAM' tables, you can specify an `AUTO_INCREMENT' secondary
column in a multiple-column key. In this case, reuse of values deleted
from the top of the sequence occurs even for `MyISAM' tables. See *Note
example-auto-increment::.

The *Note `DELETE': delete. statement supports the following modifiers:

   * If you specify `LOW_PRIORITY', the server delays execution of the
     *Note `DELETE': delete.  until no other clients are reading from
     the table. This affects only storage engines that use only
     table-level locking (`MyISAM', `MEMORY', `MERGE').

   * For `MyISAM' tables, if you use the `QUICK' keyword, the storage
     engine does not merge index leaves during delete, which may speed
     up some kinds of delete operations.

   * The `IGNORE' keyword causes MySQL to ignore all errors during the
     process of deleting rows. (Errors encountered during the parsing
     stage are processed in the usual manner.) Errors that are ignored
     due to the use of `IGNORE' are returned as warnings.

The speed of delete operations may also be affected by factors
discussed in *Note delete-speed::.

In `MyISAM' tables, deleted rows are maintained in a linked list and
subsequent *Note `INSERT': insert. operations reuse old row positions.
To reclaim unused space and reduce file sizes, use the *Note `OPTIMIZE
TABLE': optimize-table. statement or the *Note `myisamchk': myisamchk.
utility to reorganize tables.  *Note `OPTIMIZE TABLE': optimize-table.
is easier to use, but *Note `myisamchk': myisamchk. is faster. See
*Note optimize-table::, and *Note myisamchk::.

The `QUICK' modifier affects whether index leaves are merged for delete
operations. `DELETE QUICK' is most useful for applications where index
values for deleted rows are replaced by similar index values from rows
inserted later. In this case, the holes left by deleted values are
reused.

`DELETE QUICK' is not useful when deleted values lead to underfilled
index blocks spanning a range of index values for which new inserts
occur again. In this case, use of `QUICK' can lead to wasted space in
the index that remains unreclaimed. Here is an example of such a
scenario:

  1. Create a table that contains an indexed `AUTO_INCREMENT' column.

  2. Insert many rows into the table. Each insert results in an index
     value that is added to the high end of the index.

  3. Delete a block of rows at the low end of the column range using
     `DELETE QUICK'.

In this scenario, the index blocks associated with the deleted index
values become underfilled but are not merged with other index blocks
due to the use of `QUICK'. They remain underfilled when new inserts
occur, because new rows do not have index values in the deleted range.
Furthermore, they remain underfilled even if you later use *Note
`DELETE': delete. without `QUICK', unless some of the deleted index
values happen to lie in index blocks within or adjacent to the
underfilled blocks. To reclaim unused index space under these
circumstances, use *Note `OPTIMIZE TABLE': optimize-table.

If you are going to delete many rows from a table, it might be faster
to use `DELETE QUICK' followed by *Note `OPTIMIZE TABLE':
optimize-table. This rebuilds the index rather than performing many
index block merge operations.

The MySQL-specific `LIMIT ROW_COUNT' option to *Note `DELETE': delete.
tells the server the maximum number of rows to be deleted before
control is returned to the client. This can be used to ensure that a
given *Note `DELETE': delete. statement does not take too much time.
You can simply repeat the *Note `DELETE': delete. statement until the
number of affected rows is less than the `LIMIT' value.

If the *Note `DELETE': delete. statement includes an `ORDER BY' clause,
rows are deleted in the order specified by the clause. This is useful
primarily in conjunction with `LIMIT'. For example, the following
statement finds rows matching the `WHERE' clause, sorts them by
`timestamp_column', and deletes the first (oldest) one:

     DELETE FROM somelog WHERE user = 'jcole'
     ORDER BY timestamp_column LIMIT 1;

`ORDER BY' may also be useful in some cases to delete rows in an order
required to avoid referential integrity violations.

If you are deleting many rows from a large table, you may exceed the
the lock table size for an `InnoDB' table. To avoid this problem, or
simply to minimize the time that the table remains locked, the
following strategy (which does not use *Note `DELETE': delete. at all)
might be helpful:

  1. Select the rows _not_ to be deleted into an empty table that has
     the same structure as the original table:

          INSERT INTO t_copy SELECT * FROM t WHERE ... ;

  2. Use *Note `RENAME TABLE': rename-table. to atomically move the
     original table out of the way and rename the copy to the original
     name:

          RENAME TABLE t TO t_old, t_copy TO t;

  3. Drop the original table:

          DROP TABLE t_old;

No other sessions can access the tables involved while *Note `RENAME
TABLE': rename-table. executes, so the rename operation is not subject
to concurrency problems. See *Note rename-table::.

You can specify multiple tables in a *Note `DELETE': delete. statement
to delete rows from one or more tables depending on the particular
condition in the `WHERE' clause. However, you cannot use `ORDER BY' or
`LIMIT' in a multiple-table *Note `DELETE': delete. The
TABLE_REFERENCES clause lists the tables involved in the join. Its
syntax is described in *Note join::.

For the first multiple-table syntax, only matching rows from the tables
listed before the `FROM' clause are deleted. For the second
multiple-table syntax, only matching rows from the tables listed in the
`FROM' clause (before the `USING' clause) are deleted. The effect is
that you can delete rows from many tables at the same time and have
additional tables that are used only for searching:

     DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3
     WHERE t1.id=t2.id AND t2.id=t3.id;

Or:

     DELETE FROM t1, t2 USING t1 INNER JOIN t2 INNER JOIN t3
     WHERE t1.id=t2.id AND t2.id=t3.id;

These statements use all three tables when searching for rows to
delete, but delete matching rows only from tables `t1' and `t2'.

The preceding examples use `INNER JOIN', but multiple-table *Note
`DELETE': delete. statements can use other types of join allowed in
*Note `SELECT': select. statements, such as `LEFT JOIN'. For example,
to delete rows that exist in `t1' that have no match in `t2', use a
`LEFT JOIN':

     DELETE t1 FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.id IS NULL;

The syntax allows `.*' after each TBL_NAME for compatibility with
`Access'.

If you use a multiple-table *Note `DELETE': delete.  statement
involving `InnoDB' tables for which there are foreign key constraints,
the MySQL optimizer might process tables in an order that differs from
that of their parent/child relationship. In this case, the statement
fails and rolls back. Instead, you should delete from a single table and
rely on the `ON DELETE' capabilities that `InnoDB' provides to cause
the other tables to be modified accordingly.

*Note*:

If you declare an alias for a table, you must use the alias when
referring to the table:

     DELETE t1 FROM test AS t1, test2 WHERE ...

Table aliases in a multiple-table *Note `DELETE': delete. statement
should be declared only in the TABLE_REFERENCES part.  Elsewhere in the
statement, alias references are allowed but not alias declarations.

Correct:

     DELETE a1, a2 FROM t1 AS a1 INNER JOIN t2 AS a2
     WHERE a1.id=a2.id;

     DELETE FROM a1, a2 USING t1 AS a1 INNER JOIN t2 AS a2
     WHERE a1.id=a2.id;

Incorrect:

     DELETE t1 AS a1, t2 AS a2 FROM t1 INNER JOIN t2
     WHERE a1.id=a2.id;

     DELETE FROM t1 AS a1, t2 AS a2 USING t1 INNER JOIN t2
     WHERE a1.id=a2.id;

Declaration of aliases other than in the TABLE_REFERENCES part can lead
to ambiguous statements that have unexpected results such as deleting
rows from the wrong table. This is such a statement:

     DELETE FROM t1 AS a2 USING t1 AS a1 INNER JOIN t2 AS a2;

Before MySQL 6.0.5, alias declarations are allowed in other than the
TABLE_REFERENCES part, but should be avoided for the reason just
mentioned.

Cross-database deletes are supported for multiple-table deletes, but
you should be aware that in the list of tables from which to delete
rows, aliases will have a default database unless one is specified
explicitly. For example, if the current database is `test', the
following statement does not work because the unqualified alias `a1'
has a default database of `test':

     DELETE a1, a2 FROM db1.t1 AS a1 INNER JOIN db2.t2 AS a2
     WHERE a1.id=a2.id;

To correctly match the alias, you must explicitly qualify it with the
database of the table being aliased:

     DELETE db1.a1, db2.a2 FROM db1.t1 AS a1 INNER JOIN db2.t2 AS a2
     WHERE a1.id=a2.id;


File: manual.info,  Node: do,  Next: handler,  Prev: delete,  Up: sql-syntax-data-manipulation

12.2.3 `DO' Syntax
------------------

     DO EXPR [, EXPR] ...

*Note `DO': do. executes the expressions but does not return any
results. In most respects, *Note `DO': do. is shorthand for `SELECT
EXPR, ...', but has the advantage that it is slightly faster when you
do not care about the result.

*Note `DO': do. is useful primarily with functions that have side
effects, such as `RELEASE_LOCK()'.


File: manual.info,  Node: handler,  Next: insert,  Prev: do,  Up: sql-syntax-data-manipulation

12.2.4 `HANDLER' Syntax
-----------------------

     HANDLER TBL_NAME OPEN [ [AS] ALIAS]
     HANDLER TBL_NAME READ INDEX_NAME { = | >= | <= | < } (VALUE1,VALUE2,...)
         [ WHERE WHERE_CONDITION ] [LIMIT ... ]
     HANDLER TBL_NAME READ INDEX_NAME { FIRST | NEXT | PREV | LAST }
         [ WHERE WHERE_CONDITION ] [LIMIT ... ]
     HANDLER TBL_NAME READ { FIRST | NEXT }
         [ WHERE WHERE_CONDITION ] [LIMIT ... ]
     HANDLER TBL_NAME CLOSE

The *Note `HANDLER': handler. statement provides direct access to table
storage engine interfaces. It is available for `MyISAM' and `InnoDB'
tables.

The `HANDLER ... OPEN' statement opens a table, making it accessible
via subsequent `HANDLER ...  READ' statements. This table object is not
shared by other sessions and is not closed until the session calls
`HANDLER ... CLOSE' or the session terminates. If you open the table
using an alias, further references to the open table with other *Note
`HANDLER': handler. statements must use the alias rather than the table
name.

The first `HANDLER ... READ' syntax fetches a row where the index
specified satisfies the given values and the `WHERE' condition is met.
If you have a multiple-column index, specify the index column values as
a comma-separated list. Either specify values for all the columns in
the index, or specify values for a leftmost prefix of the index
columns. Suppose that an index `my_idx' includes three columns named
`col_a', `col_b', and `col_c', in that order. The *Note `HANDLER':
handler. statement can specify values for all three columns in the
index, or for the columns in a leftmost prefix. For example:

     HANDLER ... READ my_idx = (col_a_val,col_b_val,col_c_val) ...
     HANDLER ... READ my_idx = (col_a_val,col_b_val) ...
     HANDLER ... READ my_idx = (col_a_val) ...

To employ the *Note `HANDLER': handler. interface to refer to a table's
`PRIMARY KEY', use the quoted identifier ``PRIMARY`':

     HANDLER TBL_NAME READ `PRIMARY` ...

The second `HANDLER ... READ' syntax fetches a row from the table in
index order that matches the `WHERE' condition.

The third `HANDLER ... READ' syntax fetches a row from the table in
natural row order that matches the `WHERE' condition. It is faster than
`HANDLER TBL_NAME READ INDEX_NAME' when a full table scan is desired.
Natural row order is the order in which rows are stored in a `MyISAM'
table data file. This statement works for `InnoDB' tables as well, but
there is no such concept because there is no separate data file.

Without a `LIMIT' clause, all forms of `HANDLER ... READ' fetch a
single row if one is available. To return a specific number of rows,
include a `LIMIT' clause. It has the same syntax as for the *Note
`SELECT': select. statement. See *Note select::.

`HANDLER ... CLOSE' closes a table that was opened with `HANDLER ...
OPEN'.

There are several reasons to use the *Note `HANDLER': handler.
interface instead of normal *Note `SELECT': select. statements:

   * *Note `HANDLER': handler. is faster than *Note `SELECT': select.:

        * A designated storage engine handler object is allocated for
          the `HANDLER ... OPEN'. The object is reused for subsequent
          *Note `HANDLER': handler. statements for that table; it need
          not be reinitialized for each one.

        * There is less parsing involved.

        * There is no optimizer or query-checking overhead.

        * The table does not have to be locked between two handler
          requests.

        * The handler interface does not have to provide a consistent
          look of the data (for example, dirty reads are allowed), so
          the storage engine can use optimizations that *Note `SELECT':
          select. does not normally allow.

   * For applications that use a low-level `ISAM'-like interface, *Note
     `HANDLER': handler. makes it much easier to port them to MySQL.

   * *Note `HANDLER': handler. enables you to traverse a database in a
     manner that is difficult (or even impossible) to accomplish with
     *Note `SELECT': select. The *Note `HANDLER': handler. interface is
     a more natural way to look at data when working with applications
     that provide an interactive user interface to the database.

*Note `HANDLER': handler. is a somewhat low-level statement. For
example, it does not provide consistency. That is, `HANDLER ... OPEN'
does _not_ take a snapshot of the table, and does _not_ lock the table.
This means that after a `HANDLER ...  OPEN' statement is issued, table
data can be modified (by the current session or other sessions) and
these modifications might be only partially visible to `HANDLER ...
NEXT' or `HANDLER ... PREV' scans.

An open handler can be closed and marked for reopen, in which case the
handler loses its position in the table. This occurs when both of the
following circumstances are true:

   * Any session executes *Note `FLUSH TABLES': flush.  or DDL
     statements on the handler's table.

   * The session in which the handler is open executes non-*Note
     `HANDLER': handler. statements that use tables.


File: manual.info,  Node: insert,  Next: load-data,  Prev: handler,  Up: sql-syntax-data-manipulation

12.2.5 `INSERT' Syntax
----------------------

* Menu:

* insert-select::                `INSERT ... SELECT' Syntax
* insert-delayed::               `INSERT DELAYED' Syntax
* insert-on-duplicate::          `INSERT ... ON DUPLICATE KEY UPDATE' Syntax

     INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE]
         [INTO] TBL_NAME [(COL_NAME,...)]
         {VALUES | VALUE} ({EXPR | DEFAULT},...),(...),...
         [ ON DUPLICATE KEY UPDATE
           COL_NAME=EXPR
             [, COL_NAME=EXPR] ... ]

Or:

     INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE]
         [INTO] TBL_NAME
         SET COL_NAME={EXPR | DEFAULT}, ...
         [ ON DUPLICATE KEY UPDATE
           COL_NAME=EXPR
             [, COL_NAME=EXPR] ... ]

Or:

     INSERT [LOW_PRIORITY | HIGH_PRIORITY] [IGNORE]
         [INTO] TBL_NAME [(COL_NAME,...)]
         SELECT ...
         [ ON DUPLICATE KEY UPDATE
           COL_NAME=EXPR
             [, COL_NAME=EXPR] ... ]

*Note `INSERT': insert. inserts new rows into an existing table. The
`INSERT ... VALUES' and `INSERT ... SET' forms of the statement insert
rows based on explicitly specified values. The *Note `INSERT ...
SELECT': insert-select. form inserts rows selected from another table or
tables. *Note `INSERT ... SELECT': insert-select. is discussed further
in *Note insert-select::.

You can use *Note `REPLACE': replace. instead of *Note `INSERT':
insert. to overwrite old rows.  *Note `REPLACE': replace. is the
counterpart to `INSERT IGNORE' in the treatment of new rows that
contain unique key values that duplicate old rows: The new rows are
used to replace the old rows rather than being discarded. See *Note
replace::.

TBL_NAME is the table into which rows should be inserted. The columns
for which the statement provides values can be specified as follows:

   * You can provide a comma-separated list of column names following
     the table name. In this case, a value for each named column must
     be provided by the `VALUES' list or the *Note `SELECT': select.
     statement.

   * If you do not specify a list of column names for `INSERT ...
     VALUES' or *Note `INSERT ... SELECT': insert-select, values for
     every column in the table must be provided by the `VALUES' list or
     the *Note `SELECT': select. statement. If you do not know the
     order of the columns in the table, use `DESCRIBE TBL_NAME' to find
     out.

   * The `SET' clause indicates the column names explicitly.

Column values can be given in several ways:

   * If you are not running in strict SQL mode, any column not
     explicitly given a value is set to its default (explicit or
     implicit) value. For example, if you specify a column list that
     does not name all the columns in the table, unnamed columns are
     set to their default values. Default value assignment is described
     in *Note data-type-defaults::. See also *Note
     constraint-invalid-data::.

     If you want an *Note `INSERT': insert. statement to generate an
     error unless you explicitly specify values for all columns that do
     not have a default value, you should use strict mode. See *Note
     server-sql-mode::.

   * Use the keyword `DEFAULT' to set a column explicitly to its
     default value. This makes it easier to write *Note `INSERT':
     insert. statements that assign values to all but a few columns,
     because it enables you to avoid writing an incomplete `VALUES' list
     that does not include a value for each column in the table.
     Otherwise, you would have to write out the list of column names
     corresponding to each value in the `VALUES' list.

     You can also use `DEFAULT(COL_NAME)' as a more general form that
     can be used in expressions to produce a given column's default
     value.

   * If both the column list and the `VALUES' list are empty, *Note
     `INSERT': insert. creates a row with each column set to its
     default value:

          INSERT INTO TBL_NAME () VALUES();

     In strict mode, an error occurs if any column doesn't have a
     default value. Otherwise, MySQL uses the implicit default value
     for any column that does not have an explicitly defined default.

   * You can specify an expression EXPR to provide a column value. This
     might involve type conversion if the type of the expression does
     not match the type of the column, and conversion of a given value
     can result in different inserted values depending on the data
     type. For example, inserting the string `'1999.0e-2'' into an
     *Note `INT': numeric-types, *Note `FLOAT': numeric-types,
     `DECIMAL(10,6)', or *Note `YEAR': year. column results in the
     values `1999', `19.9921', `19.992100', and `1999' being inserted,
     respectively. The reason the value stored in the *Note `INT':
     numeric-types. and *Note `YEAR': year. columns is `1999' is that
     the string-to-integer conversion looks only at as much of the
     initial part of the string as may be considered a valid integer or
     year. For the floating-point and fixed-point columns, the
     string-to-floating-point conversion considers the entire string a
     valid floating-point value.

     An expression EXPR can refer to any column that was set earlier in
     a value list. For example, you can do this because the value for
     `col2' refers to `col1', which has previously been assigned:

          INSERT INTO TBL_NAME (col1,col2) VALUES(15,col1*2);

     But the following is not legal, because the value for `col1'
     refers to `col2', which is assigned after `col1':

          INSERT INTO TBL_NAME (col1,col2) VALUES(col2*2,15);

     One exception involves columns that contain `AUTO_INCREMENT'
     values. Because the `AUTO_INCREMENT' value is generated after
     other value assignments, any reference to an `AUTO_INCREMENT'
     column in the assignment returns a `0'.

*Note `INSERT': insert. statements that use `VALUES' syntax can insert
multiple rows. To do this, include multiple lists of column values,
each enclosed within parentheses and separated by commas. Example:

     INSERT INTO TBL_NAME (a,b,c) VALUES(1,2,3),(4,5,6),(7,8,9);

The values list for each row must be enclosed within parentheses.  The
following statement is illegal because the number of values in the list
does not match the number of column names:

     INSERT INTO TBL_NAME (a,b,c) VALUES(1,2,3,4,5,6,7,8,9);

`VALUE' is a synonym for `VALUES' in this context. Neither implies
anything about the number of values lists, and either may be used
whether there is a single values list or multiple lists.

The affected-rows value for an *Note `INSERT': insert. can be obtained
using the `ROW_COUNT()' function (see *Note information-functions::),
or the *Note `mysql_affected_rows()': mysql-affected-rows. C API
function (see *Note mysql-affected-rows::).

If you use an `INSERT ... VALUES' statement with multiple value lists or
*Note `INSERT ... SELECT': insert-select, the statement returns an
information string in this format:

     Records: 100 Duplicates: 0 Warnings: 0

`Records' indicates the number of rows processed by the statement.
(This is not necessarily the number of rows actually inserted because
`Duplicates' can be non-zero.) `Duplicates' indicates the number of
rows that could not be inserted because they would duplicate some
existing unique index value. `Warnings' indicates the number of
attempts to insert column values that were problematic in some way.
Warnings can occur under any of the following conditions:

   * Inserting `NULL' into a column that has been declared `NOT NULL'.
     For multiple-row *Note `INSERT': insert. statements or `INSERT
     INTO ... SELECT' statements, the column is set to the implicit
     default value for the column data type. This is `0' for numeric
     types, the empty string (`''') for string types, and the `zero'
     value for date and time types.  `INSERT INTO ... SELECT'
     statements are handled the same way as multiple-row inserts
     because the server does not examine the result set from the *Note
     `SELECT': select. to see whether it returns a single row. (For a
     single-row *Note `INSERT': insert, no warning occurs when `NULL'
     is inserted into a `NOT NULL' column. Instead, the statement fails
     with an error.)

   * Setting a numeric column to a value that lies outside the column's
     range. The value is clipped to the closest endpoint of the range.

   * Assigning a value such as `'10.34 a'' to a numeric column. The
     trailing non-numeric text is stripped off and the remaining
     numeric part is inserted. If the string value has no leading
     numeric part, the column is set to `0'.

   * Inserting a string into a string column (*Note `CHAR': char, *Note
     `VARCHAR': char, *Note `TEXT': blob, or *Note `BLOB': blob.) that
     exceeds the column's maximum length. The value is truncated to the
     column's maximum length.

   * Inserting a value into a date or time column that is illegal for
     the data type. The column is set to the appropriate zero value for
     the type.

If you are using the C API, the information string can be obtained by
invoking the *Note `mysql_info()': mysql-info.  function. See *Note
mysql-info::.

If *Note `INSERT': insert. inserts a row into a table that has an
`AUTO_INCREMENT' column, you can find the value used for that column by
using the SQL `LAST_INSERT_ID()' function. From within the C API, use
the *Note `mysql_insert_id()': mysql-insert-id. function.  However, you
should note that the two functions do not always behave identically.
The behavior of *Note `INSERT': insert. statements with respect to
`AUTO_INCREMENT' columns is discussed further in *Note
information-functions::, and *Note mysql-insert-id::.

The *Note `INSERT': insert. statement supports the following modifiers:

   * If you use the `DELAYED' keyword, the server puts the row or rows
     to be inserted into a buffer, and the client issuing the *Note
     `INSERT DELAYED': insert-delayed. statement can then continue
     immediately. If the table is in use, the server holds the rows.
     When the table is free, the server begins inserting rows, checking
     periodically to see whether there are any new read requests for
     the table. If there are, the delayed row queue is suspended until
     the table becomes free again. See *Note insert-delayed::.

     `DELAYED' is ignored with *Note `INSERT ... SELECT':
     insert-select. or `INSERT ... ON DUPLICATE KEY UPDATE'.

     `DELAYED' is also disregarded for an *Note `INSERT': insert. that
     uses functions accessing tables or triggers, or that is called
     from a function or a trigger.

   * If you use the `LOW_PRIORITY' keyword, execution of the *Note
     `INSERT': insert. is delayed until no other clients are reading
     from the table.  This includes other clients that began reading
     while existing clients are reading, and while the `INSERT
     LOW_PRIORITY' statement is waiting. It is possible, therefore, for
     a client that issues an `INSERT LOW_PRIORITY' statement to wait
     for a very long time (or even forever) in a read-heavy
     environment. (This is in contrast to *Note `INSERT DELAYED':
     insert-delayed, which lets the client continue at once. Note that
     `LOW_PRIORITY' should normally not be used with `MyISAM' tables
     because doing so disables concurrent inserts. See *Note
     concurrent-inserts::.

     If you specify `HIGH_PRIORITY', it overrides the effect of the
     `--low-priority-updates' option if the server was started with
     that option. It also causes concurrent inserts not to be used. See
     *Note concurrent-inserts::.

     `LOW_PRIORITY' and `HIGH_PRIORITY' affect only storage engines
     that use only table-level locking (`MyISAM', `MEMORY', `MERGE').

   * If you use the `IGNORE' keyword, errors that occur while executing
     the *Note `INSERT': insert. statement are treated as warnings
     instead. For example, without `IGNORE', a row that duplicates an
     existing `UNIQUE' index or `PRIMARY KEY' value in the table causes
     a duplicate-key error and the statement is aborted. With `IGNORE',
     the row still is not inserted, but no error is issued.

     `IGNORE' has a similar effect on inserts into partitioned tables
     where no partition matching a given value is found. Without
     `IGNORE', such *Note `INSERT': insert. statements are aborted with
     an error; however, when `INSERT IGNORE' is used, the insert
     operation fails silently for the row containing the unmatched
     value, but any rows that are matched are inserted. For an example,
     see *Note partitioning-list::.

     Data conversions that would trigger errors abort the statement if
     `IGNORE' is not specified. With `IGNORE', invalid values are
     adjusted to the closest values and inserted; warnings are produced
     but the statement does not abort. You can determine with the *Note
     `mysql_info()': mysql-info. C API function how many rows were
     actually inserted into the table.

   * If you specify `ON DUPLICATE KEY UPDATE', and a row is inserted
     that would cause a duplicate value in a `UNIQUE' index or `PRIMARY
     KEY', an *Note `UPDATE': update. of the old row is performed. The
     affected-rows value per row is 1 if the row is inserted as a new
     row and 2 if an existing row is updated. See *Note
     insert-on-duplicate::.

Inserting into a table requires the `INSERT' privilege for the table. If
the `ON DUPLICATE KEY UPDATE' clause is used and a duplicate key causes
an *Note `UPDATE': update. to be performed instead, the statement
requires the `UPDATE' privilege for the columns to be updated. For
columns that are read but not modified you need only the `SELECT'
privilege (such as for a column referenced only on the right hand side
of an COL_NAME=EXPR assignment in an `ON DUPLICATE KEY UPDATE' clause).


File: manual.info,  Node: insert-select,  Next: insert-delayed,  Prev: insert,  Up: insert

12.2.5.1 `INSERT ... SELECT' Syntax
...................................

     INSERT [LOW_PRIORITY | HIGH_PRIORITY] [IGNORE]
         [INTO] TBL_NAME [(COL_NAME,...)]
         SELECT ...
         [ ON DUPLICATE KEY UPDATE COL_NAME=EXPR, ... ]

With *Note `INSERT ... SELECT': insert-select, you can quickly insert
many rows into a table from one or many tables. For example:

     INSERT INTO tbl_temp2 (fld_id)
       SELECT tbl_temp1.fld_order_id
       FROM tbl_temp1 WHERE tbl_temp1.fld_order_id > 100;

The following conditions hold for a *Note `INSERT ... SELECT':
insert-select. statements:

   * Specify `IGNORE' to ignore rows that would cause duplicate-key
     violations.

   * `DELAYED' is ignored with *Note `INSERT ... SELECT': insert-select.

   * The target table of the *Note `INSERT': insert. statement may
     appear in the `FROM' clause of the *Note `SELECT': select. part of
     the query.  (This was not possible in some older versions of
     MySQL.) In this case, MySQL creates a temporary table to hold the
     rows from the *Note `SELECT': select. and then inserts those rows
     into the target table. However, it remains true that you cannot
     use `INSERT INTO t ...  SELECT ... FROM t' when `t' is a
     `TEMPORARY' table, because `TEMPORARY' tables cannot be referred to
     twice in the same statement (see *Note temporary-table-problems::).

   * `AUTO_INCREMENT' columns work as usual.

   * To ensure that the binary log can be used to re-create the
     original tables, MySQL does not allow concurrent inserts for *Note
     `INSERT ... SELECT': insert-select. statements.

   * Currently, you cannot insert into a table and select from the same
     table in a subquery.

   * To avoid ambiguous column reference problems when the *Note
     `SELECT': select. and the *Note `INSERT': insert. refer to the same
     table, provide a unique alias for each table used in the *Note
     `SELECT': select. part, and qualify column names in that part with
     the appropriate alias.

In the values part of `ON DUPLICATE KEY UPDATE', you can refer to
columns in other tables, as long as you do not use `GROUP BY' in the
*Note `SELECT': select. part. One side effect is that you must qualify
non-unique column names in the values part.


File: manual.info,  Node: insert-delayed,  Next: insert-on-duplicate,  Prev: insert-select,  Up: insert

12.2.5.2 `INSERT DELAYED' Syntax
................................

     INSERT DELAYED ...

The `DELAYED' option for the *Note `INSERT': insert. statement is a
MySQL extension to standard SQL that is very useful if you have clients
that cannot or need not wait for the *Note `INSERT': insert. to
complete. This is a common situation when you use MySQL for logging and
you also periodically run *Note `SELECT': select. and *Note `UPDATE':
update. statements that take a long time to complete.

When a client uses *Note `INSERT DELAYED': insert-delayed, it gets an
okay from the server at once, and the row is queued to be inserted when
the table is not in use by any other thread.

Another major benefit of using *Note `INSERT DELAYED': insert-delayed.
is that inserts from many clients are bundled together and written in
one block. This is much faster than performing many separate inserts.

Note that *Note `INSERT DELAYED': insert-delayed. is slower than a
normal *Note `INSERT': insert. if the table is not otherwise in use.
There is also the additional overhead for the server to handle a
separate thread for each table for which there are delayed rows. This
means that you should use *Note `INSERT DELAYED': insert-delayed. only
when you are really sure that you need it.

The queued rows are held only in memory until they are inserted into
the table. This means that if you terminate *Note `mysqld': mysqld.
forcibly (for example, with `kill -9') or if *Note `mysqld': mysqld.
dies unexpectedly, _any queued rows that have not been written to disk
are lost_.

There are some constraints on the use of `DELAYED':

   * *Note `INSERT DELAYED': insert-delayed. works only with `MyISAM',
     `MEMORY', `ARCHIVE', and `BLACKHOLE' tables. For engines that do
     not support `DELAYED', an error occurs.

   * An error occurs for *Note `INSERT DELAYED': insert-delayed. if
     used with a table that has been locked with `LOCK TABLES' because
     the insert must be handled by a separate thread, not by the
     session that holds the lock.

   * For `MyISAM' tables, if there are no free blocks in the middle of
     the data file, concurrent *Note `SELECT': select. and *Note
     `INSERT': insert. statements are supported. Under these
     circumstances, you very seldom need to use *Note `INSERT DELAYED':
     insert-delayed. with `MyISAM'.

   * *Note `INSERT DELAYED': insert-delayed. should be used only for
     *Note `INSERT': insert. statements that specify value lists. The
     server ignores `DELAYED' for *Note `INSERT ... SELECT':
     insert-select. or `INSERT ... ON DUPLICATE KEY UPDATE' statements.

   * Because the *Note `INSERT DELAYED': insert-delayed.  statement
     returns immediately, before the rows are inserted, you cannot use
     `LAST_INSERT_ID()' to get the `AUTO_INCREMENT' value that the
     statement might generate.

   * `DELAYED' rows are not visible to *Note `SELECT': select.
     statements until they actually have been inserted.

   * *Note `INSERT DELAYED': insert-delayed. is treated as a normal
     *Note `INSERT': insert. if the statement inserts multiple rows and
     binary logging is enabled and the global logging format is to use
     statement-based logging (`binlog_format' is set to `STATEMENT').
     This restriction does not apply to row-based binary logging.

   * `DELAYED' is ignored on slave replication servers, so that *Note
     `INSERT DELAYED': insert-delayed. is treated as a normal *Note
     `INSERT': insert. on slaves. This is because `DELAYED' could cause
     the slave to have different data than the master.

   * Pending *Note `INSERT DELAYED': insert-delayed.  statements are
     lost if a table is write locked and *Note `ALTER TABLE':
     alter-table. is used to modify the table structure.

   * *Note `INSERT DELAYED': insert-delayed. is not supported for views.

   * *Note `INSERT DELAYED': insert-delayed. is not supported for
     partitioned tables.

The following describes in detail what happens when you use the
`DELAYED' option to *Note `INSERT': insert. or *Note `REPLACE':
replace. In this description, the `thread' is the thread that received
an *Note `INSERT DELAYED': insert-delayed. statement and `handler' is
the thread that handles all *Note `INSERT DELAYED': insert-delayed.
statements for a particular table.

   * When a thread executes a `DELAYED' statement for a table, a
     handler thread is created to process all `DELAYED' statements for
     the table, if no such handler already exists.

   * The thread checks whether the handler has previously acquired a
     `DELAYED' lock; if not, it tells the handler thread to do so. The
     `DELAYED' lock can be obtained even if other threads have a `READ'
     or `WRITE' lock on the table. However, the handler waits for all
     *Note `ALTER TABLE': alter-table. locks or *Note `FLUSH TABLES':
     flush. statements to finish, to ensure that the table structure is
     up to date.

   * The thread executes the *Note `INSERT': insert. statement, but
     instead of writing the row to the table, it puts a copy of the
     final row into a queue that is managed by the handler thread. Any
     syntax errors are noticed by the thread and reported to the client
     program.

   * The client cannot obtain from the server the number of duplicate
     rows or the `AUTO_INCREMENT' value for the resulting row, because
     the *Note `INSERT': insert. returns before the insert operation
     has been completed. (If you use the C API, the *Note
     `mysql_info()': mysql-info. function does not return anything
     meaningful, for the same reason.)

   * The binary log is updated by the handler thread when the row is
     inserted into the table. In case of multiple-row inserts, the
     binary log is updated when the first row is inserted.

   * Each time that `delayed_insert_limit' rows are written, the
     handler checks whether any *Note `SELECT': select. statements are
     still pending. If so, it allows these to execute before continuing.

   * When the handler has no more rows in its queue, the table is
     unlocked. If no new *Note `INSERT DELAYED': insert-delayed.
     statements are received within `delayed_insert_timeout' seconds,
     the handler terminates.

   * If more than `delayed_queue_size' rows are pending in a specific
     handler queue, the thread requesting *Note `INSERT DELAYED':
     insert-delayed. waits until there is room in the queue. This is
     done to ensure that *Note `mysqld': mysqld. does not use all
     memory for the delayed memory queue.

   * The handler thread shows up in the MySQL process list with
     `delayed_insert' in the `Command' column. It is killed if you
     execute a *Note `FLUSH TABLES': flush. statement or kill it with
     `KILL THREAD_ID'. However, before exiting, it first stores all
     queued rows into the table. During this time it does not accept
     any new *Note `INSERT': insert. statements from other threads. If
     you execute an *Note `INSERT DELAYED': insert-delayed. statement
     after this, a new handler thread is created.

     Note that this means that *Note `INSERT DELAYED': insert-delayed.
     statements have higher priority than normal *Note `INSERT':
     insert. statements if there is an *Note `INSERT DELAYED':
     insert-delayed.  handler running. Other update statements have to
     wait until the *Note `INSERT DELAYED': insert-delayed. queue is
     empty, someone terminates the handler thread (with `KILL
     THREAD_ID'), or someone executes a *Note `FLUSH TABLES': flush.

   * The following status variables provide information about *Note
     `INSERT DELAYED': insert-delayed. statements.

     *Status Variable*              *Meaning*
     `Delayed_insert_threads'       Number of handler threads
     `Delayed_writes'               Number of rows written with *Note
                                    `INSERT DELAYED': insert-delayed.
     `Not_flushed_delayed_rows'     Number of rows waiting to be written

     You can view these variables by issuing a *Note `SHOW STATUS':
     show-status. statement or by executing a *Note `mysqladmin
     extended-status': mysqladmin.  command.


File: manual.info,  Node: insert-on-duplicate,  Prev: insert-delayed,  Up: insert

12.2.5.3 `INSERT ... ON DUPLICATE KEY UPDATE' Syntax
....................................................

If you specify `ON DUPLICATE KEY UPDATE', and a row is inserted that
would cause a duplicate value in a `UNIQUE' index or `PRIMARY KEY', an
*Note `UPDATE': update. of the old row is performed. For example, if
column `a' is declared as `UNIQUE' and contains the value `1', the
following two statements have identical effect:

     INSERT INTO table (a,b,c) VALUES (1,2,3)
       ON DUPLICATE KEY UPDATE c=c+1;

     UPDATE table SET c=c+1 WHERE a=1;

With `ON DUPLICATE KEY UPDATE', the affected-rows value per row is 1 if
the row is inserted as a new row and 2 if an existing row is updated.

If column `b' is also unique, the *Note `INSERT': insert. is equivalent
to this *Note `UPDATE': update. statement instead:

     UPDATE table SET c=c+1 WHERE a=1 OR b=2 LIMIT 1;

If `a=1 OR b=2' matches several rows, only _one_ row is updated. In
general, you should try to avoid using an `ON DUPLICATE KEY UPDATE'
clause on tables with multiple unique indexes.

The `ON DUPLICATE KEY UPDATE' clause can contain multiple column
assignments, separated by commas.

You can use the `VALUES(COL_NAME)' function in the *Note `UPDATE':
update. clause to refer to column values from the *Note `INSERT':
insert. portion of the `INSERT ... ON DUPLICATE KEY UPDATE' statement.
In other words, `VALUES(COL_NAME)' in the `ON DUPLICATE KEY UPDATE'
clause refers to the value of COL_NAME that would be inserted, had no
duplicate-key conflict occurred. This function is especially useful in
multiple-row inserts. The `VALUES()' function is meaningful only in
`INSERT ... UPDATE' statements and returns `NULL' otherwise. Example:

     INSERT INTO table (a,b,c) VALUES (1,2,3),(4,5,6)
       ON DUPLICATE KEY UPDATE c=VALUES(a)+VALUES(b);

That statement is identical to the following two statements:

     INSERT INTO table (a,b,c) VALUES (1,2,3)
       ON DUPLICATE KEY UPDATE c=3;
     INSERT INTO table (a,b,c) VALUES (4,5,6)
       ON DUPLICATE KEY UPDATE c=9;

If a table contains an `AUTO_INCREMENT' column and `INSERT ... ON
DUPLICATE KEY UPDATE' inserts or updates a row, the `LAST_INSERT_ID()'
function returns the `AUTO_INCREMENT' value.

The `DELAYED' option is ignored when you use `ON DUPLICATE KEY UPDATE'.


File: manual.info,  Node: load-data,  Next: load-xml,  Prev: insert,  Up: sql-syntax-data-manipulation

12.2.6 `LOAD DATA INFILE' Syntax
--------------------------------

     LOAD DATA [LOW_PRIORITY | CONCURRENT] [LOCAL] INFILE 'FILE_NAME'
         [REPLACE | IGNORE]
         INTO TABLE TBL_NAME
         [CHARACTER SET CHARSET_NAME]
         [{FIELDS | COLUMNS}
             [TERMINATED BY 'STRING']
             [[OPTIONALLY] ENCLOSED BY 'CHAR']
             [ESCAPED BY 'CHAR']
         ]
         [LINES
             [STARTING BY 'STRING']
             [TERMINATED BY 'STRING']
         ]
         [IGNORE NUMBER LINES]
         [(COL_NAME_OR_USER_VAR,...)]
         [SET COL_NAME = EXPR,...]

The *Note `LOAD DATA INFILE': load-data. statement reads rows from a
text file into a table at a very high speed. The file name must be
given as a literal string.

*Note `LOAD DATA INFILE': load-data. is the complement of *Note `SELECT
... INTO OUTFILE': select. (See *Note select::.) To write data from a
table to a file, use *Note `SELECT ... INTO OUTFILE': select. To read
the file back into a table, use *Note `LOAD DATA INFILE': load-data.
The syntax of the `FIELDS' and `LINES' clauses is the same for both
statements.  Both clauses are optional, but `FIELDS' must precede
`LINES' if both are specified.

For more information about the efficiency of *Note `INSERT': insert.
versus *Note `LOAD DATA INFILE': load-data. and speeding up *Note `LOAD
DATA INFILE': load-data, see *Note insert-speed::.

The character set indicated by the `character_set_database' system
variable is used to interpret the information in the file.  `SET NAMES'
and the setting of `character_set_client' do not affect interpretation
of input. If the contents of the input file use a character set that
differs from the default, it is usually preferable to specify the
character set of the file by using the `CHARACTER SET' clause.

*Note `LOAD DATA INFILE': load-data. interprets all fields in the file
as having the same character set, regardless of the data types of the
columns into which field values are loaded. For proper interpretation of
file contents, you must ensure that it was written with the correct
character set. For example, if you write a data file with *Note
`mysqldump -T': mysqldump. or by issuing a *Note `SELECT ... INTO
OUTFILE': select. statement in *Note `mysql': mysql, be sure to use a
`--default-character-set' option with *Note `mysqldump': mysqldump. or
*Note `mysql': mysql. so that output is written in the character set to
be used when the file is loaded with *Note `LOAD DATA INFILE':
load-data.

Note that it is currently not possible to load data files that use the
`ucs2', `utf16', or `utf32' character set.

The `character_set_filesystem' system variable controls the
interpretation of the file name.

You can also load data files by using the *Note `mysqlimport':
mysqlimport. utility; it operates by sending a *Note `LOAD DATA
INFILE': load-data. statement to the server. The `--local' option causes
*Note `mysqlimport': mysqlimport. to read data files from the client
host. You can specify the `--compress' option to get better performance
over slow networks if the client and server support the compressed
protocol. See *Note mysqlimport::.

If you use `LOW_PRIORITY', execution of the *Note `LOAD DATA':
load-data. statement is delayed until no other clients are reading from
the table. This affects only storage engines that use only table-level
locking (`MyISAM', `MEMORY', `MERGE').

If you specify `CONCURRENT' with a `MyISAM' table that satisfies the
condition for concurrent inserts (that is, it contains no free blocks
in the middle), other threads can retrieve data from the table while
*Note `LOAD DATA': load-data. is executing. Using this option affects
the performance of *Note `LOAD DATA': load-data. a bit, even if no
other thread is using the table at the same time.

`CONCURRENT' is not replicated when using statement-based replication;
however, it is replicated when using row-based replication. See *Note
replication-features-load-data::, for more information.

*Note*:

Prior to MySQL 6.0.4, *Note `LOAD DATA': load-data.  performed very
poorly when importing into partitioned tables.  The statement now uses
buffering to improve performance; however, the buffer uses 130 KB
memory per partition to achieve this. (Bug#26527
(http://bugs.mysql.com/26527))

The `LOCAL' keyword, if specified, is interpreted with respect to the
client end of the connection:

   * If `LOCAL' is specified, the file is read by the client program on
     the client host and sent to the server.  The file can be given as
     a full path name to specify its exact location. If given as a
     relative path name, the name is interpreted relative to the
     directory in which the client program was started.

   * If `LOCAL' is not specified, the file must be located on the
     server host and is read directly by the server.  The server uses
     the following rules to locate the file:

        * If the file name is an absolute path name, the server uses it
          as given.

        * If the file name is a relative path name with one or more
          leading components, the server searches for the file relative
          to the server's data directory.

        * If a file name with no leading components is given, the
          server looks for the file in the database directory of the
          default database.

Note that, in the non-`LOCAL' case, these rules mean that a file named
as `./myfile.txt' is read from the server's data directory, whereas the
file named as `myfile.txt' is read from the database directory of the
default database. For example, if `db1' is the default database, the
following *Note `LOAD DATA': load-data. statement reads the file
`data.txt' from the database directory for `db1', even though the
statement explicitly loads the file into a table in the `db2' database:

     LOAD DATA INFILE 'data.txt' INTO TABLE db2.my_table;

Windows path names are specified using forward slashes rather than
backslashes. If you do use backslashes, you must double them.

For security reasons, when reading text files located on the server,
the files must either reside in the database directory or be readable
by all. Also, to use *Note `LOAD DATA INFILE': load-data. on server
files, you must have the `FILE' privilege. See *Note
privileges-provided::. For non-`LOCAL' load operations, if the
`secure_file_priv' system variable is set to a non-empty directory
name, the file to be loaded must be located in that directory.

Using `LOCAL' is a bit slower than letting the server access the files
directly, because the contents of the file must be sent over the
connection by the client to the server. On the other hand, you do not
need the `FILE' privilege to load local files.

With `LOCAL', the default behavior is the same as if `IGNORE' is
specified; this is because the server has no way to stop transmission
of the file in the middle of the operation. `IGNORE' is explained
further later in this section.

`LOCAL' works only if your server and your client both have been
enabled to allow it. For example, if *Note `mysqld': mysqld. was
started with `--local-infile=0', `LOCAL' does not work. See *Note
load-data-local::.

On Unix, if you need *Note `LOAD DATA': load-data. to read from a pipe,
you can use the following technique (here we load the listing of the
`/' directory into a table):

     mkfifo /mysql/db/x/x
     chmod 666 /mysql/db/x/x
     find / -ls > /mysql/db/x/x &
     mysql -e "LOAD DATA INFILE 'x' INTO TABLE x" x

Note that you must run the command that generates the data to be loaded
and the *Note `mysql': mysql. commands either on separate terminals, or
run the data generation process in the background (as shown in the
preceding example). If you do not do this, the pipe will block until
data is read by the *Note `mysql': mysql. process.

The *Note `REPLACE': replace. and `IGNORE' keywords control handling of
input rows that duplicate existing rows on unique key values:

   * If you specify *Note `REPLACE': replace, input rows replace
     existing rows. In other words, rows that have the same value for a
     primary key or unique index as an existing row. See *Note
     replace::.

   * If you specify `IGNORE', input rows that duplicate an existing row
     on a unique key value are skipped.  If you do not specify either
     option, the behavior depends on whether the `LOCAL' keyword is
     specified.  Without `LOCAL', an error occurs when a duplicate key
     value is found, and the rest of the text file is ignored. With
     `LOCAL', the default behavior is the same as if `IGNORE' is
     specified; this is because the server has no way to stop
     transmission of the file in the middle of the operation.

If you want to ignore foreign key constraints during the load
operation, you can issue a `SET foreign_key_checks = 0' statement
before executing *Note `LOAD DATA': load-data.

If you use *Note `LOAD DATA INFILE': load-data. on an empty `MyISAM'
table, all non-unique indexes are created in a separate batch (as for
*Note `REPAIR TABLE': repair-table.). Normally, this makes *Note `LOAD
DATA INFILE': load-data. much faster when you have many indexes. In some
extreme cases, you can create the indexes even faster by turning them
off with `ALTER TABLE ... DISABLE KEYS' before loading the file into
the table and using `ALTER TABLE ... ENABLE KEYS' to re-create the
indexes after loading the file. See *Note insert-speed::.

For both the *Note `LOAD DATA INFILE': load-data. and *Note `SELECT ...
INTO OUTFILE': select. statements, the syntax of the `FIELDS' and
`LINES' clauses is the same. Both clauses are optional, but `FIELDS'
must precede `LINES' if both are specified.

If you specify a `FIELDS' clause, each of its subclauses (`TERMINATED
BY', `[OPTIONALLY] ENCLOSED BY', and `ESCAPED BY') is also optional,
except that you must specify at least one of them.

If you specify no `FIELDS' clause, the defaults are the same as if you
had written this:

     FIELDS TERMINATED BY '\t' ENCLOSED BY '' ESCAPED BY '\\'

If you specify no `LINES' clause, the defaults are the same as if you
had written this:

     LINES TERMINATED BY '\n' STARTING BY ''

In other words, the defaults cause *Note `LOAD DATA INFILE': load-data.
to act as follows when reading input:

   * Look for line boundaries at newlines.

   * Do not skip over any line prefix.

   * Break lines into fields at tabs.

   * Do not expect fields to be enclosed within any quoting characters.

   * Interpret occurrences of tab, newline, or ``\'' preceded by ``\''
     as literal characters that are part of field values.

Conversely, the defaults cause *Note `SELECT ... INTO OUTFILE': select.
to act as follows when writing output:

   * Write tabs between fields.

   * Do not enclose fields within any quoting characters.

   * Use ``\'' to escape instances of tab, newline, or ``\'' that occur
     within field values.

   * Write newlines at the ends of lines.

Backslash is the MySQL escape character within strings, so to write
`FIELDS ESCAPED BY '\\'', you must specify two backslashes for the
value to be interpreted as a single backslash.

*Note*:

If you have generated the text file on a Windows system, you might have
to use `LINES TERMINATED BY '\r\n'' to read the file properly, because
Windows programs typically use two characters as a line terminator.
Some programs, such as `WordPad', might use `\r' as a line terminator
when writing files. To read such files, use `LINES TERMINATED BY '\r''.

If all the lines you want to read in have a common prefix that you want
to ignore, you can use `LINES STARTING BY 'PREFIX_STRING'' to skip over
the prefix, _and anything before it_. If a line does not include the
prefix, the entire line is skipped. Suppose that you issue the
following statement:

     LOAD DATA INFILE '/tmp/test.txt' INTO TABLE test
       FIELDS TERMINATED BY ','  LINES STARTING BY 'xxx';

If the data file looks like this:

     xxx"abc",1
     something xxx"def",2
     "ghi",3

The resulting rows will be `("abc",1)' and `("def",2)'. The third row
in the file is skipped because it does not contain the prefix.

The `IGNORE NUMBER LINES' option can be used to ignore lines at the
start of the file. For example, you can use `IGNORE 1 LINES' to skip
over an initial header line containing column names:

     LOAD DATA INFILE '/tmp/test.txt' INTO TABLE test IGNORE 1 LINES;

When you use *Note `SELECT ... INTO OUTFILE': select. in tandem with
*Note `LOAD DATA INFILE': load-data. to write data from a database into
a file and then read the file back into the database later, the field-
and line-handling options for both statements must match. Otherwise,
*Note `LOAD DATA INFILE': load-data. will not interpret the contents of
the file properly. Suppose that you use *Note `SELECT ... INTO
OUTFILE': select. to write a file with fields delimited by commas:

     SELECT * INTO OUTFILE 'data.txt'
       FIELDS TERMINATED BY ','
       FROM table2;

To read the comma-delimited file back in, the correct statement would
be:

     LOAD DATA INFILE 'data.txt' INTO TABLE table2
       FIELDS TERMINATED BY ',';

If instead you tried to read in the file with the statement shown
following, it wouldn't work because it instructs *Note `LOAD DATA
INFILE': load-data. to look for tabs between fields:

     LOAD DATA INFILE 'data.txt' INTO TABLE table2
       FIELDS TERMINATED BY '\t';

The likely result is that each input line would be interpreted as a
single field.

*Note `LOAD DATA INFILE': load-data. can be used to read files obtained
from external sources. For example, many programs can export data in
comma-separated values (CSV) format, such that lines have fields
separated by commas and enclosed within double quotes. If lines in such
a file are terminated by newlines, the statement shown here illustrates
the field- and line-handling options you would use to load the file:

     LOAD DATA INFILE 'data.txt' INTO TABLE TBL_NAME
       FIELDS TERMINATED BY ',' ENCLOSED BY '"'
       LINES TERMINATED BY '\n';

If the input values are not necessarily enclosed within quotes, use
`OPTIONALLY' before the `ENCLOSED BY' keywords.

Any of the field- or line-handling options can specify an empty string
(`'''). If not empty, the `FIELDS [OPTIONALLY] ENCLOSED BY' and `FIELDS
ESCAPED BY' values must be a single character. The `FIELDS TERMINATED
BY', `LINES STARTING BY', and `LINES TERMINATED BY' values can be more
than one character. For example, to write lines that are terminated by
carriage return/linefeed pairs, or to read a file containing such
lines, specify a `LINES TERMINATED BY '\r\n'' clause.

To read a file containing jokes that are separated by lines consisting
of `%%', you can do this

     CREATE TABLE jokes
       (a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
       joke TEXT NOT NULL);
     LOAD DATA INFILE '/tmp/jokes.txt' INTO TABLE jokes
       FIELDS TERMINATED BY ''
       LINES TERMINATED BY '\n%%\n' (joke);

`FIELDS [OPTIONALLY] ENCLOSED BY' controls quoting of fields. For output
(*Note `SELECT ... INTO OUTFILE': select.), if you omit the word
`OPTIONALLY', all fields are enclosed by the `ENCLOSED BY' character.
An example of such output (using a comma as the field delimiter) is
shown here:

     "1","a string","100.20"
     "2","a string containing a , comma","102.20"
     "3","a string containing a \" quote","102.20"
     "4","a string containing a \", quote and comma","102.20"

If you specify `OPTIONALLY', the `ENCLOSED BY' character is used only
to enclose values from columns that have a string data type (such as
*Note `CHAR': char, *Note `BINARY': binary-varbinary, *Note `TEXT':
blob, or *Note `ENUM': enum.):

     1,"a string",100.20
     2,"a string containing a , comma",102.20
     3,"a string containing a \" quote",102.20
     4,"a string containing a \", quote and comma",102.20

Note that occurrences of the `ENCLOSED BY' character within a field
value are escaped by prefixing them with the `ESCAPED BY' character.
Also note that if you specify an empty `ESCAPED BY' value, it is
possible to inadvertently generate output that cannot be read properly
by *Note `LOAD DATA INFILE': load-data. For example, the preceding
output just shown would appear as follows if the escape character is
empty. Observe that the second field in the fourth line contains a comma
following the quote, which (erroneously) appears to terminate the field:

     1,"a string",100.20
     2,"a string containing a , comma",102.20
     3,"a string containing a " quote",102.20
     4,"a string containing a ", quote and comma",102.20

For input, the `ENCLOSED BY' character, if present, is stripped from
the ends of field values. (This is true regardless of whether
`OPTIONALLY' is specified; `OPTIONALLY' has no effect on input
interpretation.) Occurrences of the `ENCLOSED BY' character preceded by
the `ESCAPED BY' character are interpreted as part of the current field
value.

If the field begins with the `ENCLOSED BY' character, instances of that
character are recognized as terminating a field value only if followed
by the field or line `TERMINATED BY' sequence. To avoid ambiguity,
occurrences of the `ENCLOSED BY' character within a field value can be
doubled and are interpreted as a single instance of the character. For
example, if `ENCLOSED BY '"'' is specified, quotes are handled as shown
here:

     "The ""BIG"" boss"  -> The "BIG" boss
     The "BIG" boss      -> The "BIG" boss
     The ""BIG"" boss    -> The ""BIG"" boss

`FIELDS ESCAPED BY' controls how to write or read special characters.
If the `FIELDS ESCAPED BY' character is not empty, it is used to prefix
the following characters on output:

   * The `FIELDS ESCAPED BY' character

   * The `FIELDS [OPTIONALLY] ENCLOSED BY' character

   * The first character of the `FIELDS TERMINATED BY' and `LINES
     TERMINATED BY' values

   * ASCII `0' (what is actually written following the escape character
     is ASCII ``0'', not a zero-valued byte)

If the `FIELDS ESCAPED BY' character is empty, no characters are
escaped and `NULL' is output as `NULL', not `\N'. It is probably not a
good idea to specify an empty escape character, particularly if field
values in your data contain any of the characters in the list just
given.

For input, if the `FIELDS ESCAPED BY' character is not empty,
occurrences of that character are stripped and the following character
is taken literally as part of a field value.  Some two-character
sequences that are exceptions, where the first character is the escape
character. These sequences are shown in the following table (using
``\'' for the escape character). The rules for `NULL' handling are
described later in this section.

`\0'    An ASCII NUL (`0x00') character
`\b'    A backspace character
`\n'    A newline (linefeed) character
`\r'    A carriage return character
`\t'    A tab character.
`\Z'    ASCII 26 (Control-Z)
`\N'    NULL

For more information about ``\''-escape syntax, see *Note literals::.

In certain cases, field- and line-handling options interact:

   * If `LINES TERMINATED BY' is an empty string and `FIELDS TERMINATED
     BY' is non-empty, lines are also terminated with `FIELDS TERMINATED
     BY'.

   * If the `FIELDS TERMINATED BY' and `FIELDS ENCLOSED BY' values are
     both empty (`'''), a fixed-row (non-delimited) format is used.
     With fixed-row format, no delimiters are used between fields (but
     you can still have a line terminator). Instead, column values are
     read and written using a field width wide enough to hold all
     values in the field. For *Note `TINYINT': numeric-types, *Note
     `SMALLINT': numeric-types, *Note `MEDIUMINT': numeric-types, *Note
     `INT': numeric-types, and *Note `BIGINT': numeric-types, the field
     widths are 4, 6, 8, 11, and 20, respectively, no matter what the
     declared display width is.

     `LINES TERMINATED BY' is still used to separate lines. If a line
     does not contain all fields, the rest of the columns are set to
     their default values. If you do not have a line terminator, you
     should set this to `'''. In this case, the text file must contain
     all fields for each row.

     Fixed-row format also affects handling of `NULL' values, as
     described later. Note that fixed-size format does not work if you
     are using a multi-byte character set.

Handling of `NULL' values varies according to the `FIELDS' and `LINES'
options in use:

   * For the default `FIELDS' and `LINES' values, `NULL' is written as
     a field value of `\N' for output, and a field value of `\N' is
     read as `NULL' for input (assuming that the `ESCAPED BY' character
     is ``\'').

   * If `FIELDS ENCLOSED BY' is not empty, a field containing the
     literal word `NULL' as its value is read as a `NULL' value. This
     differs from the word `NULL' enclosed within `FIELDS ENCLOSED BY'
     characters, which is read as the string `'NULL''.

   * If `FIELDS ESCAPED BY' is empty, `NULL' is written as the word
     `NULL'.

   * With fixed-row format (which is used when `FIELDS TERMINATED BY'
     and `FIELDS ENCLOSED BY' are both empty), `NULL' is written as an
     empty string. Note that this causes both `NULL' values and empty
     strings in the table to be indistinguishable when written to the
     file because both are written as empty strings. If you need to be
     able to tell the two apart when reading the file back in, you
     should not use fixed-row format.

An attempt to load `NULL' into a `NOT NULL' column causes assignment of
the implicit default value for the column's data type and a warning, or
an error in strict SQL mode. Implicit default values are discussed in
*Note data-type-defaults::.

Some cases are not supported by *Note `LOAD DATA INFILE': load-data.:

   * Fixed-size rows (`FIELDS TERMINATED BY' and `FIELDS ENCLOSED BY'
     both empty) and *Note `BLOB': blob. or *Note `TEXT': blob. columns.

   * If you specify one separator that is the same as or a prefix of
     another, *Note `LOAD DATA INFILE': load-data. cannot interpret the
     input properly. For example, the following `FIELDS' clause would
     cause problems:

          FIELDS TERMINATED BY '"' ENCLOSED BY '"'

   * If `FIELDS ESCAPED BY' is empty, a field value that contains an
     occurrence of `FIELDS ENCLOSED BY' or `LINES TERMINATED BY'
     followed by the `FIELDS TERMINATED BY' value causes *Note `LOAD
     DATA INFILE': load-data. to stop reading a field or line too early.
     This happens because *Note `LOAD DATA INFILE': load-data. cannot
     properly determine where the field or line value ends.

The following example loads all columns of the `persondata' table:

     LOAD DATA INFILE 'persondata.txt' INTO TABLE persondata;

By default, when no column list is provided at the end of the *Note
`LOAD DATA INFILE': load-data. statement, input lines are expected to
contain a field for each table column. If you want to load only some of
a table's columns, specify a column list:

     LOAD DATA INFILE 'persondata.txt' INTO TABLE persondata (col1,col2,...);

You must also specify a column list if the order of the fields in the
input file differs from the order of the columns in the table.
Otherwise, MySQL cannot tell how to match input fields with table
columns.

The column list can contain either column names or user variables.
With user variables, the `SET' clause enables you to perform
transformations on their values before assigning the result to columns.

User variables in the `SET' clause can be used in several ways. The
following example uses the first input column directly for the value of
`t1.column1', and assigns the second input column to a user variable
that is subjected to a division operation before being used for the
value of `t1.column2':

     LOAD DATA INFILE 'file.txt'
       INTO TABLE t1
       (column1, @var1)
       SET column2 = @var1/100;

The `SET' clause can be used to supply values not derived from the
input file. The following statement sets `column3' to the current date
and time:

     LOAD DATA INFILE 'file.txt'
       INTO TABLE t1
       (column1, column2)
       SET column3 = CURRENT_TIMESTAMP;

You can also discard an input value by assigning it to a user variable
and not assigning the variable to a table column:

     LOAD DATA INFILE 'file.txt'
       INTO TABLE t1
       (column1, @dummy, column2, @dummy, column3);

Use of the column/variable list and `SET' clause is subject to the
following restrictions:

   * Assignments in the `SET' clause should have only column names on
     the left hand side of assignment operators.

   * You can use subqueries in the right hand side of `SET'
     assignments. A subquery that returns a value to be assigned to a
     column may be a scalar subquery only. Also, you cannot use a
     subquery to select from the table that is being loaded.

   * Lines ignored by an `IGNORE' clause are not processed for the
     column/variable list or `SET' clause.

   * User variables cannot be used when loading data with fixed-row
     format because user variables do not have a display width.

When processing an input line, *Note `LOAD DATA': load-data. splits it
into fields and uses the values according to the column/variable list
and the `SET' clause, if they are present. Then the resulting row is
inserted into the table. If there are `BEFORE INSERT' or `AFTER INSERT'
triggers for the table, they are activated before or after inserting
the row, respectively.

If an input line has too many fields, the extra fields are ignored and
the number of warnings is incremented.

If an input line has too few fields, the table columns for which input
fields are missing are set to their default values. Default value
assignment is described in *Note data-type-defaults::.

An empty field value is interpreted differently than if the field value
is missing:

   * For string types, the column is set to the empty string.

   * For numeric types, the column is set to `0'.

   * For date and time types, the column is set to the appropriate
     `zero' value for the type. See *Note date-and-time-types::.

These are the same values that result if you assign an empty string
explicitly to a string, numeric, or date or time type explicitly in an
*Note `INSERT': insert. or *Note `UPDATE': update. statement.

*Note `TIMESTAMP': datetime. columns are set to the current date and
time only if there is a `NULL' value for the column (that is, `\N') and
the column is not declared to allow `NULL' values, or if the *Note
`TIMESTAMP': datetime. column's default value is the current timestamp
and it is omitted from the field list when a field list is specified.

*Note `LOAD DATA INFILE': load-data. regards all input as strings, so
you cannot use numeric values for *Note `ENUM': enum. or *Note `SET':
set. columns the way you can with *Note `INSERT': insert. statements.
All *Note `ENUM': enum. and *Note `SET': set. values must be specified
as strings.

*Note `BIT': numeric-types. values cannot be loaded using binary
notation (for example, `b'011010''). To work around this, specify the
values as regular integers and use the `SET' clause to convert them so
that MySQL performs a numeric type conversion and loads them into the
*Note `BIT': numeric-types. column properly:

     shell> cat /tmp/bit_test.txt
     2
     127
     shell> mysql test
     mysql> LOAD DATA INFILE '/tmp/bit_test.txt'
         -> INTO TABLE bit_test (@var1) SET b= CAST(@var1 AS UNSIGNED);
     Query OK, 2 rows affected (0.00 sec)
     Records: 2  Deleted: 0  Skipped: 0  Warnings: 0

     mysql> SELECT BIN(b+0) FROM bit_test;
     +----------+
     | bin(b+0) |
     +----------+
     | 10       |
     | 1111111  |
     +----------+
     2 rows in set (0.00 sec)

When the *Note `LOAD DATA INFILE': load-data. statement finishes, it
returns an information string in the following format:

     Records: 1  Deleted: 0  Skipped: 0  Warnings: 0

If you are using the C API, you can get information about the statement
by calling the *Note `mysql_info()': mysql-info. function. See *Note
mysql-info::.

Warnings occur under the same circumstances as when values are inserted
via the *Note `INSERT': insert. statement (see *Note insert::), except
that *Note `LOAD DATA INFILE': load-data. also generates warnings when
there are too few or too many fields in the input row. The warnings are
not stored anywhere; the number of warnings can be used only as an
indication of whether everything went well.

You can use *Note `SHOW WARNINGS': show-warnings. to get a list of the
first `max_error_count' warnings as information about what went wrong.
See *Note show-warnings::.


File: manual.info,  Node: load-xml,  Next: replace,  Prev: load-data,  Up: sql-syntax-data-manipulation

12.2.7 `LOAD XML' Syntax
------------------------

     LOAD XML [LOW_PRIORITY | CONCURRENT] [LOCAL] INFILE 'FILE_NAME'
     [REPLACE | IGNORE]
     INTO TABLE [DB_NAME.]TBL_NAME
     [CHARACTER SET CHARSET_NAME]
     [ROWS IDENTIFIED BY '<TAGNAME>']
     [IGNORE NUMBER [LINES | ROWS]]
     [(COLUMN_OR_USER_VAR,...)]
     [SET COL_NAME = EXPR,...]

The *Note `LOAD XML': load-xml. statement reads data from an XML file
into a table. The FILE_NAME must be given as a literal string. The
TAGNAME in the optional `ROWS IDENTIFIED BY' clause must also be given
as a literal string, and must be surrounded by angle brackets (`<' and
`>').

*Note `LOAD XML': load-xml. acts as the complement of running the *Note
`mysql': mysql. client in XML output mode (that is, starting the client
with the `--xml' option). To write data from a table to an XML file,
use a command such as the following one from the system shell:

     shell> mysql --xml -e 'SELECT * FROM mytable' > file.xml

To read the file back into a table, use `LOAD XML INFILE'. By default,
the `<row>' element is considered to be the equivalent of a database
table row; this can be changed using the `ROWS IDENTIFIED BY' clause.

This statement supports three different XML formats:

   * Column names as attributes and column values as attribute values:

          <ROW COLUMN1="VALUE1" COLUMN2="VALUE2" .../>

   * Column names as tags and column values as the content of these
     tags:

          <ROW>
            <COLUMN1>VALUE1</COLUMN1>
            <COLUMN2>VALUE2</COLUMN2>
          </ROW>

   * Column names are the `name' attributes of `<field>' tags, and
     values are the contents of these tags:

          <row>
            <field name='COLUMN1'>VALUE1</field>
            <field name='COLUMN2'>VALUE2</field>
          </row>

     This is the format used by other MySQL tools, such as *Note
     `mysqldump': mysqldump.

All 3 formats can be used in the same XML file; the import routine
automatically detects the format for each row and interpets it
correctly. Tags are matched based on the tag or attribute name and the
column name.

The following clauses work essentially the same way for *Note `LOAD
XML': load-xml. as they do for *Note `LOAD DATA': load-data.:

   * `LOW_PRIORITY' or `CONCURRENT'

   * `LOCAL'

   * *Note `REPLACE': replace. or `IGNORE'

   * `CHARACTER SET'

   * `(COLUMN_OR_USER_VAR,...)'

   * `SET'

See *Note load-data::, for more information about these clauses.

The `IGNORE NUMBER LINES' or `IGNORE NUMBER ROWS' clause causes the
first NUMBER rows in the XML file to be skipped. It is analogous to the
*Note `LOAD DATA': load-data. statement's `IGNORE ... LINES' clause.

To illustrate how this statement is used, suppose that we have a table
created as follows:

     USE test;

     CREATE TABLE person (
         person_id INT NOT NULL PRIMARY KEY,
         fname VARCHAR(40) NULL,
         lname VARCHAR(40) NULL,
         created TIMESTAMP
     );

Suppose further that this table is initially empty.

Now suppose we have a simple XML file `person.xml', whose contents are
as shown here:

     <?xml version="1.0"?>
     <list>
       <person person_id="1" fname="Pekka" lname="Nousiainen"/>
       <person person_id="2" fname="Jonas" lname="Oreland"/>
       <person person_id="3"><fname>Mikael</fname><lname>Ronstro"m</lname></person>
       <person person_id="4"><fname>Lars</fname><lname>Thalmann</lname></person>
       <person><field name="person_id">5</field><field name="fname">Tomas</field><field name="lname">Ulin</field></person>
       <person><field name="person_id">6</field><field name="fname">Martin</field><field name="lname">Sko"ld</field></person>
     </list>

Each of the allowable XML formats discussed previously is represented
in this example file.

To import the data in `person.xml' into the `person' table, you can use
this statement:

     mysql> LOAD XML LOCAL INFILE 'person.xml'
         ->   INTO TABLE person
         ->   ROWS IDENTIFIED BY '<person>';

     Query OK, 6 rows affected (0.00 sec)
     Records: 6  Deleted: 0  Skipped: 0  Warnings: 0

Here, we assume that `person.xml' is located in the MySQL data
directory. If the file cannot be found, the following error results:

     `ERROR 2 (HY000): File '/person.xml' not found (Errcode: 2)'

The `ROWS IDENTIFIED BY '<person>'' clause means that each `<person>'
element in the XML file is considered equivalent to a row in the table
into which the data is to be imported. In this case, this is the
`person' table in the `test' database.

As can be seen by the response from the server, 6 rows were imported
into the `test.person' table. This can be verified by a simple *Note
`SELECT': select.  statement:

     mysql> SELECT * FROM person;
     +-----------+--------+------------+---------------------+
     | person_id | fname  | lname      | created             |
     +-----------+--------+------------+---------------------+
     |         1 | Pekka  | Nousiainen | 2007-07-13 16:18:47 |
     |         2 | Jonas  | Oreland    | 2007-07-13 16:18:47 |
     |         3 | Mikael | Ronstro"m   | 2007-07-13 16:18:47 |
     |         4 | Lars   | Thalmann   | 2007-07-13 16:18:47 |
     |         5 | Tomas  | Ulin       | 2007-07-13 16:18:47 |
     |         6 | Martin | Sko"ld      | 2007-07-13 16:18:47 |
     +-----------+--------+------------+---------------------+
     6 rows in set (0.00 sec)

This is shows, as stated earlier in this section, that any or all of
the 3 permitted XML formats may appear in a single file and be read in
using *Note `LOAD XML': load-xml.

The inverse of the above operation -- that is, dumping MySQL table data
into an XML file -- can be accomplished using the mysql client from the
system shell, as shown here:

*Note*:

The `--xml' option causes the *Note `mysql': mysql. client to use XML
formatting for its output; the `-e' option causes the client to execute
the SQL statement immediately following the option.

     shell> mysql --xml -e "SELECT * FROM test.person" > person-dump.xml
     shell> cat person-dump.xml
     <?xml version="1.0"?>

     <resultset statement="SELECT * FROM test.person" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
       <row>
             <field name="person_id">1</field>
             <field name="fname">Pekka</field>
             <field name="lname">Nousiainen</field>
             <field name="created">2007-07-13 16:18:47</field>
       </row>

       <row>
             <field name="person_id">2</field>
             <field name="fname">Jonas</field>
             <field name="lname">Oreland</field>
             <field name="created">2007-07-13 16:18:47</field>
       </row>

       <row>
             <field name="person_id">3</field>
             <field name="fname">Mikael</field>
             <field name="lname">Ronstro"m</field>
             <field name="created">2007-07-13 16:18:47</field>
       </row>

       <row>
             <field name="person_id">4</field>
             <field name="fname">Lars</field>
             <field name="lname">Thalmann</field>
             <field name="created">2007-07-13 16:18:47</field>
       </row>

       <row>
             <field name="person_id">5</field>
             <field name="fname">Tomas</field>
             <field name="lname">Ulin</field>
             <field name="created">2007-07-13 16:18:47</field>
       </row>

       <row>
             <field name="person_id">6</field>
             <field name="fname">Martin</field>
             <field name="lname">Sko"ld</field>
             <field name="created">2007-07-13 16:18:47</field>
       </row>
     </resultset>

You can verify that the dump is valid by creating a copy of the
`person' and then importing the dump file into the new table, like this:

     mysql> USE test;
     mysql> CREATE TABLE person2 LIKE person;
     Query OK, 0 rows affected (0.00 sec)

     mysql> LOAD XML LOCAL INFILE 'person-dump.xml'
         ->   INTO TABLE person2;
     Query OK, 6 rows affected (0.01 sec)
     Records: 6  Deleted: 0  Skipped: 0  Warnings: 0

     mysql> SELECT * FROM person2;
     +-----------+--------+------------+---------------------+
     | person_id | fname  | lname      | created             |
     +-----------+--------+------------+---------------------+
     |         1 | Pekka  | Nousiainen | 2007-07-13 16:18:47 |
     |         2 | Jonas  | Oreland    | 2007-07-13 16:18:47 |
     |         3 | Mikael | Ronstro"m   | 2007-07-13 16:18:47 |
     |         4 | Lars   | Thalmann   | 2007-07-13 16:18:47 |
     |         5 | Tomas  | Ulin       | 2007-07-13 16:18:47 |
     |         6 | Martin | Sko"ld      | 2007-07-13 16:18:47 |
     +-----------+--------+------------+---------------------+
     6 rows in set (0.00 sec)

Using a `ROWS IDENTIFIED BY '<TAGNAME>'' clause, it is possible to
import data from the same XML file into database tables with different
definitions. For this example, suppose you have a file named
`address.xml' which contains the following XML:

     <?xml version="1.0"?>

     <list>
       <person person_id="1">
         <fname>Robert</fname>
         <lname>Jones</lname>
         <address address_id="1" street="Mill Creek Road" zip="45365" city="Sidney"/>
         <address address_id="2" street="Main Street" zip="28681" city="Taylorsville"/>
       </person>

       <person person_id="2">
         <fname>Mary</fname>
         <lname>Smith</lname>
         <address address_id="3" street="River Road" zip="80239" city="Denver"/>
         <!-- <address address_id="4" street="North Street" zip="37920" city="Knoxville"/> -->
       </person>

     </list>

You can again use the `test.person' table as defined previously in this
section, after clearing all the existing records from the table and
then showing its structure as shown here:

     mysql< TRUNCATE person;
     Query OK, 0 rows affected (0.04 sec)

     mysql< SHOW CREATE TABLE person\G
     *************************** 1. row ***************************
            Table: person
     Create Table: CREATE TABLE `person` (
       `person_id` int(11) NOT NULL,
       `fname` varchar(40) DEFAULT NULL,
       `lname` varchar(40) DEFAULT NULL,
       `created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
       PRIMARY KEY (`person_id`)
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1
     1 row in set (0.00 sec)

Now create an `address' table in the `test' database using the following
*Note `CREATE TABLE': create-table. statement:

     CREATE TABLE address (
         address_id INT NOT NULL PRIMARY KEY,
         person_id INT NULL,
         street VARCHAR(40) NULL,
         zip INT NULL,
         city VARCHAR(40) NULL,
         created TIMESTAMP
     );

To import the data from the XML file into the `person' table, execute
the following *Note `LOAD XML': load-xml. statement, which specifies
that rows are to be specified by the `<person>' element, as shown here;

     mysql> LOAD XML LOCAL INFILE 'address.xml'
         ->   INTO TABLE person
         ->   ROWS IDENTIFIED BY '<person>';
     Query OK, 2 rows affected (0.00 sec)
     Records: 2  Deleted: 0  Skipped: 0  Warnings: 0

You can verify that the records were imported using a *Note `SELECT':
select. statement:

     mysql> SELECT * FROM person;
     +-----------+--------+-------+---------------------+
     | person_id | fname  | lname | created             |
     +-----------+--------+-------+---------------------+
     |         1 | Robert | Jones | 2007-07-24 17:37:06 |
     |         2 | Mary   | Smith | 2007-07-24 17:37:06 |
     +-----------+--------+-------+---------------------+
     2 rows in set (0.00 sec)

Since the `<address>' elements in the XML file have no corresponding
columns in the `person' table, they are skipped.

To import the data from the `<address>' elements into the `address'
table, use the *Note `LOAD XML': load-xml. statement shown here:

     mysql> LOAD XML LOCAL INFILE 'address.xml'
         ->   INTO TABLE address
         ->   ROWS IDENTIFIED BY '<address>';
     Query OK, 3 rows affected (0.00 sec)
     Records: 3  Deleted: 0  Skipped: 0  Warnings: 0

You can see that the data was imported using a *Note `SELECT': select.
statement such as this one:

     mysql> SELECT * FROM address;
     +------------+-----------+-----------------+-------+--------------+---------------------+
     | address_id | person_id | street          | zip   | city         | created             |
     +------------+-----------+-----------------+-------+--------------+---------------------+
     |          1 |         1 | Mill Creek Road | 45365 | Sidney       | 2007-07-24 17:37:37 |
     |          2 |         1 | Main Street     | 28681 | Taylorsville | 2007-07-24 17:37:37 |
     |          3 |         2 | River Road      | 80239 | Denver       | 2007-07-24 17:37:37 |
     +------------+-----------+-----------------+-------+--------------+---------------------+
     3 rows in set (0.00 sec)

The data from the `<address>' element that is enclosed in XML comments
is not imported. However, since there is a `person_id' column in the
`address' table, the value of the `person_id' attribute from the parent
`<person>' element for each `<address>' _is_ imported into the
`address' table.

Security Considerations

As with the *Note `LOAD DATA': load-data. statement, the transfer of
the XML file from the client host to the server host is initiated by
the MySQL server. In theory, a patched server could be built that would
tell the client program to transfer a file of the server's choosing
rather than the file named by the client in the *Note `LOAD XML':
load-xml. statement. Such a server could access any file on the client
host to which the client user has read access.

In a Web environment, clients usually connect to MySQL from a Web
server. A user that can run any command against the MySQL server can
use `LOAD XML LOCAL' to read any files to which the Web server process
has read access. In this environment, the client with respect to the
MySQL server is actually the Web server, not the remote program being
run by the user who connects to the Web server.

You can disable loading of XML files from clients by starting the
server with `--local-infile=0' or `--local-infile=OFF'. This option can
also be used when starting the *Note `mysql': mysql. client to disable
*Note `LOAD XML': load-xml. for the duration of the client session.

To prevent a client from loading XML files from the server, do not
grant the `FILE' privilege to the corresponding MySQL user account, or
revoke this privilege if the client user account already has it.

*Important*:

Revoking the `FILE' privilege (or not granting it in the first place)
keeps the user only from executing the `LOAD XML INFILE' statement (as
well as the `LOAD_FILE()' function; it does _not_ prevent the user from
executing `LOAD XML LOCAL INFILE'. To disallow this statement, you must
start the server or the client with `--local-infile=OFF'.

In other words, the `FILE' privilege affects only whether the client
can read files on the server; it has no bearing on whether the client
can read files on the local file system.


File: manual.info,  Node: replace,  Next: select,  Prev: load-xml,  Up: sql-syntax-data-manipulation

12.2.8 `REPLACE' Syntax
-----------------------

     REPLACE [LOW_PRIORITY | DELAYED]
         [INTO] TBL_NAME [(COL_NAME,...)]
         {VALUES | VALUE} ({EXPR | DEFAULT},...),(...),...

Or:

     REPLACE [LOW_PRIORITY | DELAYED]
         [INTO] TBL_NAME
         SET COL_NAME={EXPR | DEFAULT}, ...

Or:

     REPLACE [LOW_PRIORITY | DELAYED]
         [INTO] TBL_NAME [(COL_NAME,...)]
         SELECT ...

*Note `REPLACE': replace. works exactly like *Note `INSERT': insert,
except that if an old row in the table has the same value as a new row
for a `PRIMARY KEY' or a `UNIQUE' index, the old row is deleted before
the new row is inserted. See *Note insert::.

*Note `REPLACE': replace. is a MySQL extension to the SQL standard. It
either inserts, or _deletes_ and inserts. For another MySQL extension
to standard SQL -- that either inserts or _updates_ -- see *Note
insert-on-duplicate::.

Note that unless the table has a `PRIMARY KEY' or `UNIQUE' index, using
a *Note `REPLACE': replace. statement makes no sense.  It becomes
equivalent to *Note `INSERT': insert, because there is no index to be
used to determine whether a new row duplicates another.

Values for all columns are taken from the values specified in the *Note
`REPLACE': replace. statement. Any missing columns are set to their
default values, just as happens for *Note `INSERT': insert. You cannot
refer to values from the current row and use them in the new row. If
you use an assignment such as `SET COL_NAME = COL_NAME + 1', the
reference to the column name on the right hand side is treated as
`DEFAULT(COL_NAME)', so the assignment is equivalent to `SET COL_NAME =
DEFAULT(COL_NAME) + 1'.

To use *Note `REPLACE': replace, you must have both the `INSERT' and
`DELETE' privileges for the table.

The *Note `REPLACE': replace. statement returns a count to indicate the
number of rows affected. This is the sum of the rows deleted and
inserted. If the count is 1 for a single-row *Note `REPLACE': replace,
a row was inserted and no rows were deleted. If the count is greater
than 1, one or more old rows were deleted before the new row was
inserted. It is possible for a single row to replace more than one old
row if the table contains multiple unique indexes and the new row
duplicates values for different old rows in different unique indexes.

The affected-rows count makes it easy to determine whether *Note
`REPLACE': replace. only added a row or whether it also replaced any
rows: Check whether the count is 1 (added) or greater (replaced).

If you are using the C API, the affected-rows count can be obtained
using the *Note `mysql_affected_rows()': mysql-affected-rows. function.

Currently, you cannot replace into a table and select from the same
table in a subquery.

MySQL uses the following algorithm for *Note `REPLACE': replace. (and
`LOAD DATA ...  REPLACE'):

  1. Try to insert the new row into the table

  2. While the insertion fails because a duplicate-key error occurs for
     a primary key or unique index:

       1. Delete from the table the conflicting row that has the
          duplicate key value

       2. Try again to insert the new row into the table


File: manual.info,  Node: select,  Next: subqueries,  Prev: replace,  Up: sql-syntax-data-manipulation

12.2.9 `SELECT' Syntax
----------------------

* Menu:

* join::                         `JOIN' Syntax
* index-hints::                  Index Hint Syntax
* union::                        `UNION' Syntax

     SELECT
         [ALL | DISTINCT | DISTINCTROW ]
           [HIGH_PRIORITY]
           [STRAIGHT_JOIN]
           [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT]
           [SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS]
         SELECT_EXPR [, SELECT_EXPR ...]
         [FROM TABLE_REFERENCES
         [WHERE WHERE_CONDITION]
         [GROUP BY {COL_NAME | EXPR | POSITION}
           [ASC | DESC], ... [WITH ROLLUP]]
         [HAVING WHERE_CONDITION]
         [ORDER BY {COL_NAME | EXPR | POSITION}
           [ASC | DESC], ...]
         [LIMIT {[OFFSET,] ROW_COUNT | ROW_COUNT OFFSET OFFSET}]
         [PROCEDURE PROCEDURE_NAME(ARGUMENT_LIST)]
         [INTO OUTFILE 'FILE_NAME' EXPORT_OPTIONS
           | INTO DUMPFILE 'FILE_NAME'
           | INTO VAR_NAME [, VAR_NAME]]
         [FOR UPDATE | LOCK IN SHARE MODE]]

*Note `SELECT': select. is used to retrieve rows selected from one or
more tables, and can include *Note `UNION': union. statements and
subqueries.  See *Note union::, and *Note subqueries::.

The most commonly used clauses of *Note `SELECT': select. statements
are these:

   * Each SELECT_EXPR indicates a column that you want to retrieve.
     There must be at least one SELECT_EXPR.

   * TABLE_REFERENCES indicates the table or tables from which to
     retrieve rows. Its syntax is described in *Note join::.

   * The `WHERE' clause, if given, indicates the condition or
     conditions that rows must satisfy to be selected.  WHERE_CONDITION
     is an expression that evaluates to true for each row to be
     selected. The statement selects all rows if there is no `WHERE'
     clause.

     In the `WHERE' clause, you can use any of the functions and
     operators that MySQL supports, except for aggregate (summary)
     functions. See *Note functions::.

*Note `SELECT': select. can also be used to retrieve rows computed
without reference to any table.

For example:

     mysql> SELECT 1 + 1;
             -> 2

You are allowed to specify `DUAL' as a dummy table name in situations
where no tables are referenced:

     mysql> SELECT 1 + 1 FROM DUAL;
             -> 2

`DUAL' is purely for the convenience of people who require that all
*Note `SELECT': select.  statements should have `FROM' and possibly
other clauses. MySQL may ignore the clauses. MySQL does not require
`FROM DUAL' if no tables are referenced.

In general, clauses used must be given in exactly the order shown in
the syntax description. For example, a `HAVING' clause must come after
any `GROUP BY' clause and before any `ORDER BY' clause. The exception
is that the `INTO' clause can appear either as shown in the syntax
description or immediately following the SELECT_EXPR list.

The list of SELECT_EXPR terms comprises the select list that indicates
which columns to retrieve. Terms specify a column or expression or can
use `*'-shorthand:

   * A select list consisting only of a single unqualified `*' can be
     used as shorthand to select all columns from all tables:

          SELECT * FROM t1 INNER JOIN t2 ...

   * `TBL_NAME.*' can be used as a qualified shorthand to select all
     columns from the named table:

          SELECT t1.*, t2.* FROM t1 INNER JOIN t2 ...

   * Use of an unqualified `*' with other items in the select list may
     produce a parse error. To avoid this problem, use a qualified
     `TBL_NAME.*' reference

          SELECT AVG(score), t1.* FROM t1 ...

The following list provides additional information about other `SELECT'
clauses:

   * A SELECT_EXPR can be given an alias using `AS ALIAS_NAME'. The
     alias is used as the expression's column name and can be used in
     `GROUP BY', `ORDER BY', or `HAVING' clauses. For example:

          SELECT CONCAT(last_name,', ',first_name) AS full_name
            FROM mytable ORDER BY full_name;

     The `AS' keyword is optional when aliasing a SELECT_EXPR. The
     preceding example could have been written like this:

          SELECT CONCAT(last_name,', ',first_name) full_name
            FROM mytable ORDER BY full_name;

     However, because the `AS' is optional, a subtle problem can occur
     if you forget the comma between two SELECT_EXPR expressions: MySQL
     interprets the second as an alias name. For example, in the
     following statement, `columnb' is treated as an alias name:

          SELECT columna columnb FROM mytable;

     For this reason, it is good practice to be in the habit of using
     `AS' explicitly when specifying column aliases.

     It is not allowable to refer to a column alias in a `WHERE'
     clause, because the column value might not yet be determined when
     the `WHERE' clause is executed. See *Note problems-with-alias::.

   * The `FROM TABLE_REFERENCES' clause indicates the table or tables
     from which to retrieve rows. If you name more than one table, you
     are performing a join. For information on join syntax, see *Note
     join::. For each table specified, you can optionally specify an
     alias.

          TBL_NAME [[AS] ALIAS] [INDEX_HINT]

     The use of index hints provides the optimizer with information
     about how to choose indexes during query processing. For a
     description of the syntax for specifying these hints, see *Note
     index-hints::.

     You can use `SET max_seeks_for_key=VALUE' as an alternative way to
     force MySQL to prefer key scans instead of table scans. See *Note
     server-system-variables::.

   * You can refer to a table within the default database as TBL_NAME,
     or as DB_NAME.TBL_NAME to specify a database explicitly. You can
     refer to a column as COL_NAME, TBL_NAME.COL_NAME, or
     DB_NAME.TBL_NAME.COL_NAME.  You need not specify a TBL_NAME or
     DB_NAME.TBL_NAME prefix for a column reference unless the
     reference would be ambiguous. See *Note identifier-qualifiers::,
     for examples of ambiguity that require the more explicit column
     reference forms.

   * A table reference can be aliased using `TBL_NAME AS ALIAS_NAME' or
     TBL_NAME ALIAS_NAME:

          SELECT t1.name, t2.salary FROM employee AS t1, info AS t2
            WHERE t1.name = t2.name;

          SELECT t1.name, t2.salary FROM employee t1, info t2
            WHERE t1.name = t2.name;

   * Columns selected for output can be referred to in `ORDER BY' and
     `GROUP BY' clauses using column names, column aliases, or column
     positions. Column positions are integers and begin with 1:

          SELECT college, region, seed FROM tournament
            ORDER BY region, seed;

          SELECT college, region AS r, seed AS s FROM tournament
            ORDER BY r, s;

          SELECT college, region, seed FROM tournament
            ORDER BY 2, 3;

     To sort in reverse order, add the `DESC' (descending) keyword to
     the name of the column in the `ORDER BY' clause that you are
     sorting by.  The default is ascending order; this can be specified
     explicitly using the `ASC' keyword.

     If `ORDER BY' occurs within a subquery and also is applied in the
     outer query, the outermost `ORDER BY' takes precedence. For
     example, results for the following statement are sorted in
     descending order, not ascending order:

          (SELECT ... ORDER BY a) ORDER BY a DESC;

     Use of column positions is deprecated because the syntax has been
     removed from the SQL standard.

   * If you use `GROUP BY', output rows are sorted according to the
     `GROUP BY' columns as if you had an `ORDER BY' for the same
     columns. To avoid the overhead of sorting that `GROUP BY'
     produces, add `ORDER BY NULL':

          SELECT a, COUNT(b) FROM test_table GROUP BY a ORDER BY NULL;

   * MySQL extends the `GROUP BY' clause so that you can also specify
     `ASC' and `DESC' after columns named in the clause:

          SELECT a, COUNT(b) FROM test_table GROUP BY a DESC;

   * MySQL extends the use of `GROUP BY' to allow selecting fields that
     are not mentioned in the `GROUP BY' clause. If you are not getting
     the results that you expect from your query, please read the
     description of `GROUP BY' found in *Note
     group-by-functions-and-modifiers::.

   * `GROUP BY' allows a `WITH ROLLUP' modifier. See *Note
     group-by-modifiers::.

   * The `HAVING' clause is applied nearly last, just before items are
     sent to the client, with no optimization. (`LIMIT' is applied after
     `HAVING'.)

     The SQL standard requires that `HAVING' must reference only
     columns in the `GROUP BY' clause or columns used in aggregate
     functions. However, MySQL supports an extension to this behavior,
     and allows `HAVING' to refer to columns in the *Note `SELECT':
     select. list and columns in outer subqueries as well.

     If the `HAVING' clause refers to a column that is ambiguous, a
     warning occurs. In the following statement, `col2' is ambiguous
     because it is used as both an alias and a column name:

          SELECT COUNT(col1) AS col2 FROM t GROUP BY col2 HAVING col2 = 2;

     Preference is given to standard SQL behavior, so if a `HAVING'
     column name is used both in `GROUP BY' and as an aliased column in
     the output column list, preference is given to the column in the
     `GROUP BY' column.

   * Do not use `HAVING' for items that should be in the `WHERE'
     clause. For example, do not write the following:

          SELECT COL_NAME FROM TBL_NAME HAVING COL_NAME > 0;

     Write this instead:

          SELECT COL_NAME FROM TBL_NAME WHERE COL_NAME > 0;

   * The `HAVING' clause can refer to aggregate functions, which the
     `WHERE' clause cannot:

          SELECT user, MAX(salary) FROM users
            GROUP BY user HAVING MAX(salary) > 10;

     (This did not work in some older versions of MySQL.)

   * MySQL allows duplicate column names. That is, there can be more
     than one SELECT_EXPR with the same name. This is an extension to
     standard SQL. Because MySQL also allows `GROUP BY' and `HAVING' to
     refer to SELECT_EXPR values, this can result in an ambiguity:

          SELECT 12 AS a, a FROM t GROUP BY a;

     In that statement, both columns have the name `a'. To ensure that
     the correct column is used for grouping, use different names for
     each SELECT_EXPR.

   * MySQL resolves unqualified column or alias references in `ORDER
     BY' clauses by searching in the SELECT_EXPR values, then in the
     columns of the tables in the `FROM' clause.  For `GROUP BY' or
     `HAVING' clauses, it searches the `FROM' clause before searching
     in the SELECT_EXPR values. (For `GROUP BY' and `HAVING', this
     differs from the pre-MySQL 5.0 behavior that used the same rules
     as for `ORDER BY'.)

   * The `LIMIT' clause can be used to constrain the number of rows
     returned by the *Note `SELECT': select. statement.  `LIMIT' takes
     one or two numeric arguments, which must both be non-negative
     integer constants (except when using prepared statements).

     With two arguments, the first argument specifies the offset of the
     first row to return, and the second specifies the maximum number
     of rows to return. The offset of the initial row is 0 (not 1):

          SELECT * FROM tbl LIMIT 5,10;  # Retrieve rows 6-15

     To retrieve all rows from a certain offset up to the end of the
     result set, you can use some large number for the second
     parameter. This statement retrieves all rows from the 96th row to
     the last:

          SELECT * FROM tbl LIMIT 95,18446744073709551615;

     With one argument, the value specifies the number of rows to
     return from the beginning of the result set:

          SELECT * FROM tbl LIMIT 5;     # Retrieve first 5 rows

     In other words, `LIMIT ROW_COUNT' is equivalent to `LIMIT 0,
     ROW_COUNT'.

     For prepared statements, you can use placeholders. The following
     statements will return one row from the `tbl' table:

          SET @a=1;
          PREPARE STMT FROM 'SELECT * FROM tbl LIMIT ?';
          EXECUTE STMT USING @a;

     The following statements will return the second to sixth row from
     the `tbl' table:

          SET @skip=1; SET @numrows=5;
          PREPARE STMT FROM 'SELECT * FROM tbl LIMIT ?, ?';
          EXECUTE STMT USING @skip, @numrows;

     For compatibility with PostgreSQL, MySQL also supports the `LIMIT
     ROW_COUNT OFFSET OFFSET' syntax.

     If `LIMIT' occurs within a subquery and also is applied in the
     outer query, the outermost `LIMIT' takes precedence. For example,
     the following statement produces two rows, not one:

          (SELECT ... LIMIT 1) LIMIT 2;

   * A `PROCEDURE' clause names a procedure that should process the
     data in the result set. For an example, see *Note
     procedure-analyse::.

   * The `SELECT ... INTO OUTFILE 'FILE_NAME'' form of *Note `SELECT':
     select. writes the selected rows to a file. The file is created on
     the server host, so you must have the `FILE' privilege to use this
     syntax. FILE_NAME cannot be an existing file, which among other
     things prevents files such as `/etc/passwd' and database tables
     from being destroyed. The `character_set_filesystem' system
     variable controls the interpretation of the file name.

     The *Note `SELECT ... INTO OUTFILE': select. statement is intended
     primarily to let you very quickly dump a table to a text file on
     the server machine. If you want to create the resulting file on
     some client host other than the server host, you cannot use *Note
     `SELECT ... INTO OUTFILE': select. In that case, you should
     instead use a command such as `mysql -e "SELECT ..." > FILE_NAME'
     to generate the file on the client host.

     *Note `SELECT ... INTO OUTFILE': select. is the complement of
     *Note `LOAD DATA INFILE': load-data.; the syntax for the
     EXPORT_OPTIONS part of the statement consists of the same `FIELDS'
     and `LINES' clauses that are used with the *Note `LOAD DATA
     INFILE': load-data. statement. See *Note load-data::.

     Column values are dumped using the `binary' character set. In
     effect, there is no character set conversion. If a table contains
     columns in several character sets, the output data file will as
     well and you may not be able to reload the file correctly.

     `FIELDS ESCAPED BY' controls how to write special characters. If
     the `FIELDS ESCAPED BY' character is not empty, it is used as a
     prefix that precedes following characters on output:

        * The `FIELDS ESCAPED BY' character

        * The `FIELDS [OPTIONALLY] ENCLOSED BY' character

        * The first character of the `FIELDS TERMINATED BY' and `LINES
          TERMINATED BY' values

        * ASCII `NUL' (the zero-valued byte; what is actually written
          following the escape character is ASCII ``0'', not a
          zero-valued byte)

     The `FIELDS TERMINATED BY', `ENCLOSED BY', `ESCAPED BY', or `LINES
     TERMINATED BY' characters _must_ be escaped so that you can read
     the file back in reliably.  ASCII `NUL' is escaped to make it
     easier to view with some pagers.

     The resulting file does not have to conform to SQL syntax, so
     nothing else need be escaped.

     If the `FIELDS ESCAPED BY' character is empty, no characters are
     escaped and `NULL' is output as `NULL', not `\N'. It is probably
     not a good idea to specify an empty escape character, particularly
     if field values in your data contain any of the characters in the
     list just given.

     Here is an example that produces a file in the comma-separated
     values (CSV) format used by many programs:

          SELECT a,b,a+b INTO OUTFILE '/tmp/result.txt'
            FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
            LINES TERMINATED BY '\n'
            FROM test_table;

   * If you use `INTO DUMPFILE' instead of `INTO OUTFILE', MySQL writes
     only one row into the file, without any column or line termination
     and without performing any escape processing. This is useful if
     you want to store a *Note `BLOB': blob. value in a file.

   * *Note*:

     Any file created by `INTO OUTFILE' or `INTO DUMPFILE' is writable
     by all users on the server host. The reason for this is that the
     MySQL server cannot create a file that is owned by anyone other
     than the user under whose account it is running. (You should
     _never_ run *Note `mysqld': mysqld. as `root' for this and other
     reasons.) The file thus must be world-writable so that you can
     manipulate its contents.

     If the `secure_file_priv' system variable is set to a non-empty
     directory name, the file to be written must be located in that
     directory.

   * The `INTO' clause can name a list of one or more variables, which
     can be user-defined variables, or parameters or local variables
     within a stored function or procedure body (see *Note
     select-into-statement::).  The selected values are assigned to the
     variables. The number of variables must match the number of
     columns. The query should return a single row. If the query
     returns no rows, a warning with error code 1329 occurs (`No
     data'), and the variable values remain unchanged. If the query
     returns multiple rows, error 1172 occurs (`Result consisted of
     more than one row'). If it is possible that the statement may
     retrieve multiple rows, you can use `LIMIT 1' to limit the result
     set to a single row.

     In the context of such statements that occur as part of events
     executed by the Event Scheduler, diagnostics messages (not only
     errors, but also warnings) are written to the error log, and, on
     Windows, to the application event log. For additional information,
     see *Note events-status-info::.

   * The *Note `SELECT': select. syntax description at the beginning
     this section shows the `INTO' clause near the end of the statement.
     It is also possible to use `INTO' immediately following the
     SELECT_EXPR list.

   * An `INTO' clause should not be used in a nested *Note `SELECT':
     select. because such a *Note `SELECT': select. must return its
     result to the outer context.

   * If you use `FOR UPDATE' with a storage engine that uses page or
     row locks, rows examined by the query are write-locked until the
     end of the current transaction. Using `LOCK IN SHARE MODE' sets a
     shared lock that allows other transactions to read the examined
     rows but not to update or delete them. See *Note
     innodb-locking-reads::.

Following the *Note `SELECT': select. keyword, you can use a number of
options that affect the operation of the statement.

The `ALL', `DISTINCT', and `DISTINCTROW' options specify whether
duplicate rows should be returned. If none of these options are given,
the default is `ALL' (all matching rows are returned). `DISTINCT' and
`DISTINCTROW' are synonyms and specify removal of duplicate rows from
the result set.

`HIGH_PRIORITY', `STRAIGHT_JOIN', and options beginning with `SQL_' are
MySQL extensions to standard SQL.

   * `HIGH_PRIORITY' gives the *Note `SELECT': select. higher priority
     than a statement that updates a table. You should use this only for
     queries that are very fast and must be done at once. A `SELECT
     HIGH_PRIORITY' query that is issued while the table is locked for
     reading runs even if there is an update statement waiting for the
     table to be free. This affects only storage engines that use only
     table-level locking (`MyISAM', `MEMORY', `MERGE').

     `HIGH_PRIORITY' cannot be used with *Note `SELECT': select.
     statements that are part of a *Note `UNION': union.

   * `STRAIGHT_JOIN' is a hint to the optimizer that it should join the
     tables in the order in which they are listed in the `FROM' clause.
     You can use this to speed up a query if the optimizer joins the
     tables in non-optimal order. `STRAIGHT_JOIN' also can be used in
     the TABLE_REFERENCES list. See *Note join::.

     `STRAIGHT_JOIN' does not apply to any table that the optimizer
     treats as a `const' or `system' table. Such a table produces a
     single row, is read during the optimization phase of query
     execution, and references to its columns are replaced with the
     appropriate column values before query execution proceeds. These
     tables will appear first in the query plan displayed by *Note
     `EXPLAIN': explain. See *Note using-explain::. This exception may
     not apply to `const' or `system' tables that are used on the
     `NULL'-complemented side of an outer join (that is, the right-side
     table of a `LEFT JOIN' or the left-side table of a `RIGHT JOIN'.

   * `SQL_BIG_RESULT' can be used with `GROUP BY' or `DISTINCT' to tell
     the optimizer that the result set has many rows. In this case,
     MySQL directly uses disk-based temporary tables if needed, and
     prefers sorting to using a temporary table with a key on the
     `GROUP BY' elements.

   * `SQL_BUFFER_RESULT' forces the result to be put into a temporary
     table. This helps MySQL free the table locks early and helps in
     cases where it takes a long time to send the result set to the
     client. This option can be used only for top-level *Note `SELECT':
     select.  statements, not for subqueries or following *Note
     `UNION': union.

   * `SQL_SMALL_RESULT' can be used with `GROUP BY' or `DISTINCT' to
     tell the optimizer that the result set is small. In this case,
     MySQL uses fast temporary tables to store the resulting table
     instead of using sorting. This should not normally be needed.

   * `SQL_CALC_FOUND_ROWS' tells MySQL to calculate how many rows there
     would be in the result set, disregarding any `LIMIT' clause. The
     number of rows can then be retrieved with `SELECT FOUND_ROWS()'.
     See *Note information-functions::.

   * The `SQL_CACHE' and `SQL_NO_CACHE' options affect caching of query
     results in the query cache (see *Note query-cache::). `SQL_CACHE'
     tells MySQL to store the result in the query cache if it is
     cacheable and the value of the `query_cache_type' system variable
     is `2' or `DEMAND'.  `SQL_NO_CACHE' tells MySQL not to store the
     result in the query cache.

     For views, `SQL_NO_CACHE' applies if it appears in any *Note
     `SELECT': select. in the query. For a cacheable query, `SQL_CACHE'
     applies if it appears in the first *Note `SELECT': select. of a
     view referred to by the query.

     As of MySQL 6.0.6, the parser checks whether both of these options
     appear in the same *Note `SELECT': select. statement and generates
     an error if so. Also, these options are disallowed in subqueries
     (including subqueries in the `FROM' clause, and *Note `SELECT':
     select. statements in unions other than the first *Note `SELECT':
     select.

     Before MySQL 6.0.6, for a query that uses *Note `UNION': union. or
     subqueries, the following rules apply:

        * `SQL_NO_CACHE' applies if it appears in any *Note `SELECT':
          select. in the query.

        * For a cacheable query, `SQL_CACHE' applies if it appears in
          the first *Note `SELECT': select. of the query.


File: manual.info,  Node: join,  Next: index-hints,  Prev: select,  Up: select

12.2.9.1 `JOIN' Syntax
......................

MySQL supports the following `JOIN' syntaxes for the TABLE_REFERENCES
part of *Note `SELECT': select. statements and multiple-table *Note
`DELETE': delete. and *Note `UPDATE': update. statements:

     TABLE_REFERENCES:
         TABLE_REFERENCE [, TABLE_REFERENCE] ...

     TABLE_REFERENCE:
         TABLE_FACTOR
       | JOIN_TABLE

     TABLE_FACTOR:
         TBL_NAME [[AS] ALIAS] [INDEX_HINT_LIST]
       | TABLE_SUBQUERY [AS] ALIAS
       | ( TABLE_REFERENCES )
       | { OJ TABLE_REFERENCE LEFT OUTER JOIN TABLE_REFERENCE
             ON CONDITIONAL_EXPR }

     JOIN_TABLE:
         TABLE_REFERENCE [INNER | CROSS] JOIN TABLE_FACTOR [JOIN_CONDITION]
       | TABLE_REFERENCE STRAIGHT_JOIN TABLE_FACTOR
       | TABLE_REFERENCE STRAIGHT_JOIN TABLE_FACTOR ON CONDITIONAL_EXPR
       | TABLE_REFERENCE {LEFT|RIGHT} [OUTER] JOIN TABLE_REFERENCE JOIN_CONDITION
       | TABLE_REFERENCE NATURAL [{LEFT|RIGHT} [OUTER]] JOIN TABLE_FACTOR

     JOIN_CONDITION:
         ON CONDITIONAL_EXPR
       | USING (COLUMN_LIST)

     INDEX_HINT_LIST:
         INDEX_HINT [, INDEX_HINT] ...

     INDEX_HINT:
         USE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] ([INDEX_LIST])
       | IGNORE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] (INDEX_LIST)
       | FORCE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] (INDEX_LIST)

     INDEX_LIST:
         INDEX_NAME [, INDEX_NAME] ...

A table reference is also known as a join expression.

The syntax of TABLE_FACTOR is extended in comparison with the SQL
Standard. The latter accepts only TABLE_REFERENCE, not a list of them
inside a pair of parentheses.

This is a conservative extension if we consider each comma in a list of
TABLE_REFERENCE items as equivalent to an inner join. For example:

     SELECT * FROM t1 LEFT JOIN (t2, t3, t4)
                      ON (t2.a=t1.a AND t3.b=t1.b AND t4.c=t1.c)

is equivalent to:

     SELECT * FROM t1 LEFT JOIN (t2 CROSS JOIN t3 CROSS JOIN t4)
                      ON (t2.a=t1.a AND t3.b=t1.b AND t4.c=t1.c)

In MySQL, `CROSS JOIN' is a syntactic equivalent to `INNER JOIN' (they
can replace each other). In standard SQL, they are not equivalent.
`INNER JOIN' is used with an `ON' clause, `CROSS JOIN' is used
otherwise.

In general, parentheses can be ignored in join expressions containing
only inner join operations. MySQL also supports nested joins (see *Note
nested-join-optimization::).

Index hints can be specified to affect how the MySQL optimizer makes
use of indexes. For more information, see *Note index-hints::.

The following list describes general factors to take into account when
writing joins.

   * A table reference can be aliased using `TBL_NAME AS ALIAS_NAME' or
     TBL_NAME ALIAS_NAME:

          SELECT t1.name, t2.salary
            FROM employee AS t1 INNER JOIN info AS t2 ON t1.name = t2.name;

          SELECT t1.name, t2.salary
            FROM employee t1 INNER JOIN info t2 ON t1.name = t2.name;

   * A TABLE_SUBQUERY is also known as a subquery in the `FROM' clause.
     Such subqueries _must_ include an alias to give the subquery
     result a table name. A trivial example follows; see also *Note
     unnamed-views::.

          SELECT * FROM (SELECT 1, 2, 3) AS t1;

   * `INNER JOIN' and `,' (comma) are semantically equivalent in the
     absence of a join condition: both produce a Cartesian product
     between the specified tables (that is, each and every row in the
     first table is joined to each and every row in the second table).

     However, the precedence of the comma operator is less than of
     `INNER JOIN', `CROSS JOIN', `LEFT JOIN', and so on. If you mix
     comma joins with the other join types when there is a join
     condition, an error of the form `Unknown column 'COL_NAME' in 'on
     clause'' may occur. Information about dealing with this problem is
     given later in this section.

   * The CONDITIONAL_EXPR used with `ON' is any conditional expression
     of the form that can be used in a `WHERE' clause.  Generally, you
     should use the `ON' clause for conditions that specify how to join
     tables, and the `WHERE' clause to restrict which rows you want in
     the result set.

   * If there is no matching row for the right table in the `ON' or
     `USING' part in a `LEFT JOIN', a row with all columns set to
     `NULL' is used for the right table. You can use this fact to find
     rows in a table that have no counterpart in another table:

          SELECT left_tbl.*
            FROM left_tbl LEFT JOIN right_tbl ON left_tbl.id = right_tbl.id
            WHERE right_tbl.id IS NULL;

     This example finds all rows in `left_tbl' with an `id' value that
     is not present in `right_tbl' (that is, all rows in `left_tbl'
     with no corresponding row in `right_tbl'). This assumes that
     `right_tbl.id' is declared `NOT NULL'. See *Note
     left-join-optimization::.

   * The `USING(COLUMN_LIST)' clause names a list of columns that must
     exist in both tables. If tables `a' and `b' both contain columns
     `c1', `c2', and `c3', the following join compares corresponding
     columns from the two tables:

          a LEFT JOIN b USING (c1,c2,c3)

   * The `NATURAL [LEFT] JOIN' of two tables is defined to be
     semantically equivalent to an `INNER JOIN' or a `LEFT JOIN' with a
     `USING' clause that names all columns that exist in both tables.

   * `RIGHT JOIN' works analogously to `LEFT JOIN'. To keep code
     portable across databases, it is recommended that you use `LEFT
     JOIN' instead of `RIGHT JOIN'.

   * The `{ OJ ... LEFT OUTER JOIN ...}' syntax shown in the join
     syntax description exists only for compatibility with ODBC. The
     curly braces in the syntax should be written literally; they are
     not metasyntax as used elsewhere in syntax descriptions.

          SELECT left_tbl.*
              FROM { OJ left_tbl LEFT OUTER JOIN right_tbl ON left_tbl.id = right_tbl.id }
              WHERE right_tbl.id IS NULL;

     As of MySQL 6.0.5, you can use other types of joins within `{ OJ
     ... }', such as `INNER JOIN' or `RIGHT OUTER JOIN'. This helps
     with compatibility with some third-party applications, but is not
     official ODBC syntax.

   * `STRAIGHT_JOIN' is similar to `JOIN', except that the left table is
     always read before the right table. This can be used for those
     (few) cases for which the join optimizer puts the tables in the
     wrong order.

Some join examples:

     SELECT * FROM table1, table2;

     SELECT * FROM table1 INNER JOIN table2 ON table1.id=table2.id;

     SELECT * FROM table1 LEFT JOIN table2 ON table1.id=table2.id;

     SELECT * FROM table1 LEFT JOIN table2 USING (id);

     SELECT * FROM table1 LEFT JOIN table2 ON table1.id=table2.id
       LEFT JOIN table3 ON table2.id=table3.id;

*Join Processing Changes in MySQL 5.0.12*

*Note*:

Natural joins and joins with `USING', including outer join variants,
are processed according to the SQL:2003 standard. The goal was to align
the syntax and semantics of MySQL with respect to `NATURAL JOIN' and
`JOIN ... USING' according to SQL:2003. However, these changes in join
processing can result in different output columns for some joins. Also,
some queries that appeared to work correctly in older versions (prior
to 5.0.12) must be rewritten to comply with the standard.

These changes have five main aspects:

   * The way that MySQL determines the result columns of `NATURAL' or
     `USING' join operations (and thus the result of the entire `FROM'
     clause).

   * Expansion of `SELECT *' and `SELECT TBL_NAME.*' into a list of
     selected columns.

   * Resolution of column names in `NATURAL' or `USING' joins.

   * Transformation of `NATURAL' or `USING' joins into `JOIN ...  ON'.

   * Resolution of column names in the `ON' condition of a `JOIN ...
     ON'.

The following list provides more detail about several effects of
current join processing versus join processing in older versions. The
term `previously' means `prior to MySQL 5.0.12.'

   * The columns of a `NATURAL' join or a `USING' join may be different
     from previously. Specifically, redundant output columns no longer
     appear, and the order of columns for `SELECT *' expansion may be
     different from before.

     Consider this set of statements:

          CREATE TABLE t1 (i INT, j INT);
          CREATE TABLE t2 (k INT, j INT);
          INSERT INTO t1 VALUES(1,1);
          INSERT INTO t2 VALUES(1,1);
          SELECT * FROM t1 NATURAL JOIN t2;
          SELECT * FROM t1 JOIN t2 USING (j);

     Previously, the statements produced this output:

          +------+------+------+------+
          | i    | j    | k    | j    |
          +------+------+------+------+
          |    1 |    1 |    1 |    1 |
          +------+------+------+------+
          +------+------+------+------+
          | i    | j    | k    | j    |
          +------+------+------+------+
          |    1 |    1 |    1 |    1 |
          +------+------+------+------+

     In the first *Note `SELECT': select.  statement, column `j'
     appears in both tables and thus becomes a join column, so,
     according to standard SQL, it should appear only once in the
     output, not twice. Similarly, in the second SELECT statement,
     column `j' is named in the `USING' clause and should appear only
     once in the output, not twice. But in both cases, the redundant
     column is not eliminated. Also, the order of the columns is not
     correct according to standard SQL.

     Now the statements produce this output:

          +------+------+------+
          | j    | i    | k    |
          +------+------+------+
          |    1 |    1 |    1 |
          +------+------+------+
          +------+------+------+
          | j    | i    | k    |
          +------+------+------+
          |    1 |    1 |    1 |
          +------+------+------+

     The redundant column is eliminated and the column order is correct
     according to standard SQL:

        * First, coalesced common columns of the two joined tables, in
          the order in which they occur in the first table

        * Second, columns unique to the first table, in order in which
          they occur in that table

        * Third, columns unique to the second table, in order in which
          they occur in that table

     The single result column that replaces two common columns is
     defined via the coalesce operation. That is, for two `t1.a' and
     `t2.a' the resulting single join column `a' is defined as `a =
     COALESCE(t1.a, t2.a)', where:

          COALESCE(x, y) = (CASE WHEN V1 IS NOT NULL THEN V1 ELSE V2 END)

     If the join operation is any other join, the result columns of the
     join consists of the concatenation of all columns of the joined
     tables. This is the same as previously.

     A consequence of the definition of coalesced columns is that, for
     outer joins, the coalesced column contains the value of the
     non-`NULL' column if one of the two columns is always `NULL'. If
     neither or both columns are `NULL', both common columns have the
     same value, so it doesn't matter which one is chosen as the value
     of the coalesced column. A simple way to interpret this is to
     consider that a coalesced column of an outer join is represented
     by the common column of the inner table of a `JOIN'. Suppose that
     the tables `t1(a,b)' and `t2(a,c)' have the following contents:

          t1    t2
          ----  ----
          1 x   2 z
          2 y   3 w

     Then:

          mysql> SELECT * FROM t1 NATURAL LEFT JOIN t2;
          +------+------+------+
          | a    | b    | c    |
          +------+------+------+
          |    1 | x    | NULL |
          |    2 | y    | z    |
          +------+------+------+

     Here column `a' contains the values of `t1.a'.

          mysql> SELECT * FROM t1 NATURAL RIGHT JOIN t2;
          +------+------+------+
          | a    | c    | b    |
          +------+------+------+
          |    2 | z    | y    |
          |    3 | w    | NULL |
          +------+------+------+

     Here column `a' contains the values of `t2.a'.

     Compare these results to the otherwise equivalent queries with
     `JOIN ... ON':

          mysql> SELECT * FROM t1 LEFT JOIN t2 ON (t1.a = t2.a);
          +------+------+------+------+
          | a    | b    | a    | c    |
          +------+------+------+------+
          |    1 | x    | NULL | NULL |
          |    2 | y    |    2 | z    |
          +------+------+------+------+

          mysql> SELECT * FROM t1 RIGHT JOIN t2 ON (t1.a = t2.a);
          +------+------+------+------+
          | a    | b    | a    | c    |
          +------+------+------+------+
          |    2 | y    |    2 | z    |
          | NULL | NULL |    3 | w    |
          +------+------+------+------+

   * Previously, a `USING' clause could be rewritten as an `ON' clause
     that compares corresponding columns. For example, the following two
     clauses were semantically identical:

          a LEFT JOIN b USING (c1,c2,c3)
          a LEFT JOIN b ON a.c1=b.c1 AND a.c2=b.c2 AND a.c3=b.c3

     Now the two clauses no longer are quite the same:

        * With respect to determining which rows satisfy the join
          condition, both joins remain semantically identical.

        * With respect to determining which columns to display for
          `SELECT *' expansion, the two joins are not semantically
          identical. The `USING' join selects the coalesced value of
          corresponding columns, whereas the `ON' join selects all
          columns from all tables. For the preceding `USING' join,
          `SELECT *' selects these values:

               COALESCE(a.c1,b.c1), COALESCE(a.c2,b.c2), COALESCE(a.c3,b.c3)

          For the `ON' join, `SELECT *' selects these values:

               a.c1, a.c2, a.c3, b.c1, b.c2, b.c3

          With an inner join, `COALESCE(a.c1,b.c1)' is the same as
          either `a.c1' or `b.c1' because both columns will have the
          same value. With an outer join (such as `LEFT JOIN'), one of
          the two columns can be `NULL'. That column will be omitted
          from the result.

   * The evaluation of multi-way natural joins differs in a very
     important way that affects the result of `NATURAL' or `USING' joins
     and that can require query rewriting. Suppose that you have three
     tables `t1(a,b)', `t2(c,b)', and `t3(a,c)' that each have one row:
     `t1(1,2)', `t2(10,2)', and `t3(7,10)'. Suppose also that you have
     this `NATURAL JOIN' on the three tables:

          SELECT ... FROM t1 NATURAL JOIN t2 NATURAL JOIN t3;

     Previously, the left operand of the second join was considered to
     be `t2', whereas it should be the nested join `(t1 NATURAL JOIN
     t2)'. As a result, the columns of `t3' are checked for common
     columns only in `t2', and, if `t3' has common columns with `t1',
     these columns are not used as equi-join columns. Thus, previously,
     the preceding query was transformed to the following equi-join:

          SELECT ... FROM t1, t2, t3
            WHERE t1.b = t2.b AND t2.c = t3.c;

     That join is missing one more equi-join predicate `(t1.a = t3.a)'.
     As a result, it produces one row, not the empty result that it
     should. The correct equivalent query is this:

          SELECT ... FROM t1, t2, t3
            WHERE t1.b = t2.b AND t2.c = t3.c AND t1.a = t3.a;

     If you require the same query result in current versions of MySQL
     as in older versions, rewrite the natural join as the first
     equi-join.

   * Previously, the comma operator (`,') and `JOIN' both had the same
     precedence, so the join expression `t1, t2 JOIN t3' was
     interpreted as `((t1, t2) JOIN t3)'. Now `JOIN' has higher
     precedence, so the expression is interpreted as `(t1, (t2 JOIN
     t3))'. This change affects statements that use an `ON' clause,
     because that clause can refer only to columns in the operands of
     the join, and the change in precedence changes interpretation of
     what those operands are.

     Example:

          CREATE TABLE t1 (i1 INT, j1 INT);
          CREATE TABLE t2 (i2 INT, j2 INT);
          CREATE TABLE t3 (i3 INT, j3 INT);
          INSERT INTO t1 VALUES(1,1);
          INSERT INTO t2 VALUES(1,1);
          INSERT INTO t3 VALUES(1,1);
          SELECT * FROM t1, t2 JOIN t3 ON (t1.i1 = t3.i3);

     Previously, the *Note `SELECT': select. was legal due to the
     implicit grouping of `t1,t2' as `(t1,t2)'. Now the `JOIN' takes
     precedence, so the operands for the `ON' clause are `t2' and `t3'.
     Because `t1.i1' is not a column in either of the operands, the
     result is an `Unknown column 't1.i1' in 'on clause'' error. To
     allow the join to be processed, group the first two tables
     explicitly with parentheses so that the operands for the `ON'
     clause are `(t1,t2)' and `t3':

          SELECT * FROM (t1, t2) JOIN t3 ON (t1.i1 = t3.i3);

     Alternatively, avoid the use of the comma operator and use `JOIN'
     instead:

          SELECT * FROM t1 JOIN t2 JOIN t3 ON (t1.i1 = t3.i3);

     This change also applies to statements that mix the comma operator
     with `INNER JOIN', `CROSS JOIN', `LEFT JOIN', and `RIGHT JOIN',
     all of which now have higher precedence than the comma operator.

   * Previously, the `ON' clause could refer to columns in tables named
     to its right. Now an `ON' clause can refer only to its operands.

     Example:

          CREATE TABLE t1 (i1 INT);
          CREATE TABLE t2 (i2 INT);
          CREATE TABLE t3 (i3 INT);
          SELECT * FROM t1 JOIN t2 ON (i1 = i3) JOIN t3;

     Previously, the *Note `SELECT': select.  statement was legal. Now
     the statement fails with an `Unknown column 'i3' in 'on clause''
     error because `i3' is a column in `t3', which is not an operand of
     the `ON' clause. The statement should be rewritten as follows:

          SELECT * FROM t1 JOIN t2 JOIN t3 ON (i1 = i3);

   * Resolution of column names in `NATURAL' or `USING' joins is
     different than previously.  For column names that are outside the
     `FROM' clause, MySQL now handles a superset of the queries
     compared to previously. That is, in cases when MySQL formerly
     issued an error that some column is ambiguous, the query now is
     handled correctly. This is due to the fact that MySQL now treats
     the common columns of `NATURAL' or `USING' joins as a single
     column, so when a query refers to such columns, the query compiler
     does not consider them as ambiguous.

     Example:

          SELECT * FROM t1 NATURAL JOIN t2 WHERE b > 1;

     Previously, this query would produce an error `ERROR 1052 (23000):
     Column 'b' in where clause is ambiguous'. Now the query produces
     the correct result:

          +------+------+------+
          | b    | c    | y    |
          +------+------+------+
          |    4 |    2 |    3 |
          +------+------+------+

     One extension of MySQL compared to the SQL:2003 standard is that
     MySQL allows you to qualify the common (coalesced) columns of
     `NATURAL' or `USING' joins (just as previously), while the
     standard disallows that.


File: manual.info,  Node: index-hints,  Next: union,  Prev: join,  Up: select

12.2.9.2 Index Hint Syntax
..........................

You can provide hints to give the optimizer information about how to
choose indexes during query processing.  *Note join::, describes the
general syntax for specifying tables in a *Note `SELECT': select.
statement. The syntax for an individual table, including that for index
hints, looks like this:

     TBL_NAME [[AS] ALIAS] [INDEX_HINT_LIST]

     INDEX_HINT_LIST:
         INDEX_HINT [, INDEX_HINT] ...

     INDEX_HINT:
         USE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] ([INDEX_LIST])
       | IGNORE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] (INDEX_LIST)
       | FORCE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] (INDEX_LIST)

     INDEX_LIST:
         INDEX_NAME [, INDEX_NAME] ...

By specifying `USE INDEX (INDEX_LIST)', you can tell MySQL to use only
one of the named indexes to find rows in the table. The alternative
syntax `IGNORE INDEX (INDEX_LIST)' can be used to tell MySQL to not use
some particular index or indexes. These hints are useful if *Note
`EXPLAIN': explain. shows that MySQL is using the wrong index from the
list of possible indexes.

You can also use `FORCE INDEX', which acts like `USE INDEX
(INDEX_LIST)' but with the addition that a table scan is assumed to be
_very_ expensive. In other words, a table scan is used only if there is
no way to use one of the given indexes to find rows in the table.

Each hint requires the names of _indexes_, not the names of columns.
The name of a `PRIMARY KEY' is `PRIMARY'. To see the index names for a
table, use *Note `SHOW INDEX': show-index.

An INDEX_NAME value need not be a full index name. It can be an
unambiguous prefix of an index name. If a prefix is ambiguous, an error
occurs.

Examples:

     SELECT * FROM table1 USE INDEX (col1_index,col2_index)
       WHERE col1=1 AND col2=2 AND col3=3;

     SELECT * FROM table1 IGNORE INDEX (col3_index)
       WHERE col1=1 AND col2=2 AND col3=3;

The syntax for index hints has the following characteristics:

   * It is syntactically valid to specify an empty INDEX_LIST for `USE
     INDEX', which means `use no indexes.' Specifying an empty
     INDEX_LIST for `FORCE INDEX' or `IGNORE INDEX' is a syntax error.

   * You can specify the scope of a index hint by adding a `FOR' clause
     to the hint. This provides more fine-grained control over the
     optimizer's selection of an execution plan for various phases of
     query processing. To affect only the indexes used when MySQL
     decides how to find rows in the table and how to process joins,
     use `FOR JOIN'. To influence index usage for sorting or grouping
     rows, use `FOR ORDER BY' or `FOR GROUP BY'. (However, if there is a
     covering index for the table and it is used to access the table,
     the optimizer will ignore `IGNORE INDEX FOR {ORDER BY|GROUP BY}'
     hints that disable that index.)

   * You can specify multiple index hints:

          SELECT * FROM t1 USE INDEX (i1) IGNORE INDEX FOR ORDER BY (i2) ORDER BY a;

     It is not a error to name the same index in several hints (even
     within the same hint):

          SELECT * FROM t1 USE INDEX (i1) USE INDEX (i1,i1);

     However, it is an error to mix `USE INDEX' and `FORCE INDEX' for
     the same table:

          SELECT * FROM t1 USE INDEX FOR JOIN (i1) FORCE INDEX FOR JOIN (i2);

if you specify no `FOR' clause for an index hint, the hint by default
applies to all parts of the statement.  For example, this hint:

     IGNORE INDEX (i1)

is equivalent to this combination of hints:

     IGNORE INDEX FOR JOIN (i1)
     IGNORE INDEX FOR ORDER BY (i1)
     IGNORE INDEX FOR GROUP BY (i1)

To cause the server to use the older behavior for hint scope when no
`FOR' clause is present (so that hints apply only to row retrieval),
enable the `old' system variable at server startup. Take care about
enabling this variable in a replication setup. With statement-based
binary logging, having different modes for the master and slaves might
lead to replication errors.

When index hints are processed, they are collected in a single list by
type (*Note `USE': use, `FORCE', `IGNORE') and by scope (`FOR JOIN',
`FOR ORDER BY', `FOR GROUP BY'). For example:

     SELECT * FROM t1
       USE INDEX () IGNORE INDEX (i2) USE INDEX (i1) USE INDEX (i2);

is equivalent to:

     SELECT * FROM t1
        USE INDEX (i1,i2) IGNORE INDEX (i2);

The index hints then are applied for each scope in the following order:

  1. `{USE|FORCE} INDEX' is applied if present.  (If not, the
     optimizer-determined set of indexes is used.)

  2. `IGNORE INDEX' is applied over the result of the previous step.
     For example, the following two queries are equivalent:

          SELECT * FROM t1 USE INDEX (i1) IGNORE INDEX (i2) USE INDEX (i2);

          SELECT * FROM t1 USE INDEX (i1);

For `FULLTEXT' searches, index hints do not work before MySQL 6.0.9. As
of 6.0.9, index hints work as follows:

   * For natural language mode searches, index hints are silently
     ignored. For example, `IGNORE INDEX(i)' is ignored with no warning
     and the index is still used.

     For boolean mode searches, index hints with `FOR ORDER BY' or `FOR
     GROUP BY' are silently ignored. Index hints with `FOR JOIN' or no
     `FOR' modifier are honored. In contrast to how hints apply for
     non-`FULLTEXT' searches, the hint is used for all phases of query
     execution (finding rows and retrieval, grouping, and ordering).
     This is true even if the hint is given for a non-`FULLTEXT' index.

For example, the following two queries are equivalent:

     SELECT * FROM t
       USE INDEX (index1)
       IGNORE INDEX (index1) FOR ORDER BY
       IGNORE INDEX (index1) FOR GROUP BY
       WHERE ... IN BOOLEAN MODE ... ;

     SELECT * FROM t
       USE INDEX (index1)
       WHERE ... IN BOOLEAN MODE ... ;

Index hints are accepted but ignored for *Note `UPDATE': update.
statements.


File: manual.info,  Node: union,  Prev: index-hints,  Up: select

12.2.9.3 `UNION' Syntax
.......................

     SELECT ...
     UNION [ALL | DISTINCT] SELECT ...
     [UNION [ALL | DISTINCT] SELECT ...]

*Note `UNION': union. is used to combine the result from multiple *Note
`SELECT': select.  statements into a single result set.

The column names from the first *Note `SELECT': select. statement are
used as the column names for the results returned. Selected columns
listed in corresponding positions of each *Note `SELECT': select.
statement should have the same data type. (For example, the first
column selected by the first statement should have the same type as the
first column selected by the other statements.)

If the data types of corresponding *Note `SELECT': select. columns do
not match, the types and lengths of the columns in the *Note `UNION':
union. result take into account the values retrieved by all of the
*Note `SELECT': select. statements. For example, consider the following:

     mysql> SELECT REPEAT('a',1) UNION SELECT REPEAT('b',10);
     +---------------+
     | REPEAT('a',1) |
     +---------------+
     | a             |
     | bbbbbbbbbb    |
     +---------------+

(In some earlier versions of MySQL, only the type and length from the
first *Note `SELECT': select. would have been used and the second row
would have been truncated to a length of 1.)

The *Note `SELECT': select. statements are normal select statements,
but with the following restrictions:

   * Only the last *Note `SELECT': select.  statement can use `INTO
     OUTFILE'. (However, the entire *Note `UNION': union. result is
     written to the file.)

   * `HIGH_PRIORITY' cannot be used with *Note `SELECT': select.
     statements that are part of a *Note `UNION': union. If you specify
     it for the first *Note `SELECT': select, it has no effect. If you
     specify it for any subsequent *Note `SELECT': select. statements,
     a syntax error results.

The default behavior for *Note `UNION': union. is that duplicate rows
are removed from the result. The optional `DISTINCT' keyword has no
effect other than the default because it also specifies duplicate-row
removal. With the optional `ALL' keyword, duplicate-row removal does
not occur and the result includes all matching rows from all the *Note
`SELECT': select. statements.

You can mix *Note `UNION ALL': union. and *Note `UNION DISTINCT':
union. in the same query. Mixed *Note `UNION': union. types are treated
such that a `DISTINCT' union overrides any `ALL' union to its left. A
`DISTINCT' union can be produced explicitly by using *Note `UNION
DISTINCT': union. or implicitly by using *Note `UNION': union. with no
following `DISTINCT' or `ALL' keyword.

To use an `ORDER BY' or `LIMIT' clause to sort or limit the entire
*Note `UNION': union. result, parenthesize the individual *Note
`SELECT': select. statements and place the `ORDER BY' or `LIMIT' after
the last one. The following example uses both clauses:

     (SELECT a FROM t1 WHERE a=10 AND B=1)
     UNION
     (SELECT a FROM t2 WHERE a=11 AND B=2)
     ORDER BY a LIMIT 10;

This kind of `ORDER BY' cannot use column references that include a
table name (that is, names in TBL_NAME.COL_NAME format). Instead,
provide a column alias in the first *Note `SELECT': select. statement
and refer to the alias in the `ORDER BY'. (Alternatively, refer to the
column in the `ORDER BY' using its column position. However, use of
column positions is deprecated.)

Also, if a column to be sorted is aliased, the `ORDER BY' clause _must_
refer to the alias, not the column name. The first of the following
statements will work, but the second will fail with an `Unknown column
'a' in 'order clause'' error:

     (SELECT a AS b FROM t) UNION (SELECT ...) ORDER BY b;
     (SELECT a AS b FROM t) UNION (SELECT ...) ORDER BY a;

To apply `ORDER BY' or `LIMIT' to an individual *Note `SELECT': select,
place the clause inside the parentheses that enclose the *Note
`SELECT': select.:

     (SELECT a FROM t1 WHERE a=10 AND B=1 ORDER BY a LIMIT 10)
     UNION
     (SELECT a FROM t2 WHERE a=11 AND B=2 ORDER BY a LIMIT 10);

However, use of `ORDER BY' for individual *Note `SELECT': select.
statements implies nothing about the order in which the rows appear in
the final result because *Note `UNION': union. by default produces an
unordered set of rows. Therefore, the use of `ORDER BY' in this context
is typically in conjunction with `LIMIT', so that it is used to
determine the subset of the selected rows to retrieve for the *Note
`SELECT': select, even though it does not necessarily affect the order
of those rows in the final *Note `UNION': union. result. If `ORDER BY'
appears without `LIMIT' in a *Note `SELECT': select, it is optimized
away because it will have no effect anyway.

To cause rows in a *Note `UNION': union. result to consist of the sets
of rows retrieved by each *Note `SELECT': select. one after the other,
select an additional column in each *Note `SELECT': select. to use as a
sort column and add an `ORDER BY' following the last *Note `SELECT':
select.:

     (SELECT 1 AS sort_col, col1a, col1b, ... FROM t1)
     UNION
     (SELECT 2, col2a, col2b, ... FROM t2) ORDER BY sort_col;

To additionally maintain sort order within individual *Note `SELECT':
select. results, add a secondary column to the `ORDER BY' clause:

     (SELECT 1 AS sort_col, col1a, col1b, ... FROM t1)
     UNION
     (SELECT 2, col2a, col2b, ... FROM t2) ORDER BY sort_col, col1a;

Use of an additional column also enables you to determine which *Note
`SELECT': select. each row comes from. Extra columns can provide other
identifying information as well, such as a string that indicates a
table name.


File: manual.info,  Node: subqueries,  Next: truncate,  Prev: select,  Up: sql-syntax-data-manipulation

12.2.10 Subquery Syntax
-----------------------

* Menu:

* scalar-subqueries::            The Subquery as Scalar Operand
* comparisons-using-subqueries::  Comparisons Using Subqueries
* any-in-some-subqueries::       Subqueries with `ANY', `IN', and `SOME'
* all-subqueries::               Subqueries with `ALL'
* row-subqueries::               Row Subqueries
* exists-and-not-exists-subqueries::  `EXISTS' and `NOT EXISTS'
* correlated-subqueries::        Correlated Subqueries
* unnamed-views::                Subqueries in the `FROM' clause
* subquery-errors::              Subquery Errors
* optimizing-subqueries::        Optimizing Subqueries
* rewriting-subqueries::         Rewriting Subqueries as Joins

A subquery is a *Note `SELECT': select. statement within another
statement.

Starting with MySQL 4.1, all subquery forms and operations that the SQL
standard requires are supported, as well as a few features that are
MySQL-specific.

Here is an example of a subquery:

     SELECT * FROM t1 WHERE column1 = (SELECT column1 FROM t2);

In this example, `SELECT * FROM t1 ...' is the _outer query_ (or _outer
statement_), and `(SELECT column1 FROM t2)' is the _subquery_. We say
that the subquery is _nested_ within the outer query, and in fact it is
possible to nest subqueries within other subqueries, to a considerable
depth. A subquery must always appear within parentheses.

The main advantages of subqueries are:

   * They allow queries that are _structured_ so that it is possible to
     isolate each part of a statement.

   * They provide alternative ways to perform operations that would
     otherwise require complex joins and unions.

   * They are, in many people's opinion, more readable than complex
     joins or unions. Indeed, it was the innovation of subqueries that
     gave people the original idea of calling the early SQL `Structured
     Query Language.'

Here is an example statement that shows the major points about subquery
syntax as specified by the SQL standard and supported in MySQL:

     DELETE FROM t1
     WHERE s11 > ANY
      (SELECT COUNT(*) /* no hint */ FROM t2
       WHERE NOT EXISTS
        (SELECT * FROM t3
         WHERE ROW(5*t2.s1,77)=
          (SELECT 50,11*s1 FROM t4 UNION SELECT 50,77 FROM
           (SELECT * FROM t5) AS t5)));

A subquery can return a scalar (a single value), a single row, a single
column, or a table (one or more rows of one or more columns). These are
called scalar, column, row, and table subqueries. Subqueries that
return a particular kind of result often can be used only in certain
contexts, as described in the following sections.

There are few restrictions on the type of statements in which
subqueries can be used. A subquery can contain any of the keywords or
clauses that an ordinary *Note `SELECT': select.  can contain:
`DISTINCT', `GROUP BY', `ORDER BY', `LIMIT', joins, index hints, *Note
`UNION': union. constructs, comments, functions, and so on.

One restriction is that a subquery's outer statement must be one of:
*Note `SELECT': select, *Note `INSERT': insert, *Note `UPDATE': update,
*Note `DELETE': delete, *Note `SET': set-option, or *Note `DO': do.
Another restriction is that currently you cannot modify a table and
select from the same table in a subquery. This applies to statements
such as *Note `DELETE': delete, *Note `INSERT': insert, *Note
`REPLACE': replace, *Note `UPDATE': update, and (because subqueries can
be used in the `SET' clause) *Note `LOAD DATA INFILE': load-data.

A more comprehensive discussion of restrictions on subquery use,
including performance issues for certain forms of subquery syntax, is
given in *Note subquery-restrictions::.


File: manual.info,  Node: scalar-subqueries,  Next: comparisons-using-subqueries,  Prev: subqueries,  Up: subqueries

12.2.10.1 The Subquery as Scalar Operand
........................................

In its simplest form, a subquery is a scalar subquery that returns a
single value. A scalar subquery is a simple operand, and you can use it
almost anywhere a single column value or literal is legal, and you can
expect it to have those characteristics that all operands have: a data
type, a length, an indication whether it can be `NULL', and so on. For
example:

     CREATE TABLE t1 (s1 INT, s2 CHAR(5) NOT NULL);
     INSERT INTO t1 VALUES(100, 'abcde');
     SELECT (SELECT s2 FROM t1);

The subquery in this *Note `SELECT': select.  returns a single value
(`'abcde'') that has a data type of *Note `CHAR': char, a length of 5,
a character set and collation equal to the defaults in effect at *Note
`CREATE TABLE': create-table. time, and an indication that the value in
the column can be `NULL'. In fact, almost all subqueries can be `NULL'.
If the table used in the example were empty, the value of the subquery
would be `NULL'.

There are a few contexts in which a scalar subquery cannot be used. If
a statement allows only a literal value, you cannot use a subquery. For
example, `LIMIT' requires literal integer arguments, and *Note `LOAD
DATA INFILE': load-data. requires a literal string file name. You cannot
use subqueries to supply these values.

When you see examples in the following sections that contain the rather
spartan construct `(SELECT column1 FROM t1)', imagine that your own
code contains much more diverse and complex constructions.

Suppose that we make two tables:

     CREATE TABLE t1 (s1 INT);
     INSERT INTO t1 VALUES (1);
     CREATE TABLE t2 (s1 INT);
     INSERT INTO t2 VALUES (2);

Then perform a *Note `SELECT': select.:

     SELECT (SELECT s1 FROM t2) FROM t1;

The result is `2' because there is a row in `t2' containing a column
`s1' that has a value of `2'.

A scalar subquery can be part of an expression, but remember the
parentheses, even if the subquery is an operand that provides an
argument for a function. For example:

     SELECT UPPER((SELECT s1 FROM t1)) FROM t2;


File: manual.info,  Node: comparisons-using-subqueries,  Next: any-in-some-subqueries,  Prev: scalar-subqueries,  Up: subqueries

12.2.10.2 Comparisons Using Subqueries
......................................

The most common use of a subquery is in the form:

     NON_SUBQUERY_OPERAND COMPARISON_OPERATOR (SUBQUERY)

Where COMPARISON_OPERATOR is one of these operators:

     =  >  <  >=  <=  <>  !=  <=>

For example:

     ... 'a' = (SELECT column1 FROM t1)

At one time the only legal place for a subquery was on the right side
of a comparison, and you might still find some old DBMSs that insist on
this.

Here is an example of a common-form subquery comparison that you cannot
do with a join. It finds all the rows in table `t1' for which the
`column1' value is equal to a maximum value in table `t2':

     SELECT * FROM t1
     WHERE column1 = (SELECT MAX(column2) FROM t2);

Here is another example, which again is impossible with a join because
it involves aggregating for one of the tables. It finds all rows in
table `t1' containing a value that occurs twice in a given column:

     SELECT * FROM t1 AS t
     WHERE 2 = (SELECT COUNT(*) FROM t1 WHERE t1.id = t.id);

For a comparison of the subquery to a scalar, the subquery must return
a scalar. For a comparison of the subquery to a row constructor, the
subquery must be a row subquery that returns a row with the same number
of values as the row constructor. See *Note row-subqueries::.


File: manual.info,  Node: any-in-some-subqueries,  Next: all-subqueries,  Prev: comparisons-using-subqueries,  Up: subqueries

12.2.10.3 Subqueries with `ANY', `IN', and `SOME'
.................................................

Syntax:

     OPERAND COMPARISON_OPERATOR ANY (SUBQUERY)
     OPERAND IN (SUBQUERY)
     OPERAND COMPARISON_OPERATOR SOME (SUBQUERY)

The `ANY' keyword, which must follow a comparison operator, means
`return `TRUE' if the comparison is `TRUE' for `ANY' of the values in
the column that the subquery returns.' For example:

     SELECT s1 FROM t1 WHERE s1 > ANY (SELECT s1 FROM t2);

Suppose that there is a row in table `t1' containing `(10)'. The
expression is `TRUE' if table `t2' contains `(21,14,7)' because there
is a value `7' in `t2' that is less than `10'. The expression is
`FALSE' if table `t2' contains `(20,10)', or if table `t2' is empty.
The expression is _unknown_ if table `t2' contains `(NULL,NULL,NULL)'.

When used with a subquery, the word `IN' is an alias for `= ANY'. Thus,
these two statements are the same:

     SELECT s1 FROM t1 WHERE s1 = ANY (SELECT s1 FROM t2);
     SELECT s1 FROM t1 WHERE s1 IN    (SELECT s1 FROM t2);

`IN' and `= ANY' are not synonyms when used with an expression list.
`IN' can take an expression list, but `= ANY' cannot. See *Note
comparison-operators::.

`NOT IN' is not an alias for `<> ANY', but for `<> ALL'. See *Note
all-subqueries::.

The word `SOME' is an alias for `ANY'. Thus, these two statements are
the same:

     SELECT s1 FROM t1 WHERE s1 <> ANY  (SELECT s1 FROM t2);
     SELECT s1 FROM t1 WHERE s1 <> SOME (SELECT s1 FROM t2);

Use of the word `SOME' is rare, but this example shows why it might be
useful. To most people's ears, the English phrase `a is not equal to
any b' means `there is no b which is equal to a,' but that is not what
is meant by the SQL syntax. The syntax means `there is some b to which
a is not equal.' Using `<> SOME' instead helps ensure that everyone
understands the true meaning of the query.


File: manual.info,  Node: all-subqueries,  Next: row-subqueries,  Prev: any-in-some-subqueries,  Up: subqueries

12.2.10.4 Subqueries with `ALL'
...............................

Syntax:

     OPERAND COMPARISON_OPERATOR ALL (SUBQUERY)

The word `ALL', which must follow a comparison operator, means `return
`TRUE' if the comparison is `TRUE' for `ALL' of the values in the
column that the subquery returns.' For example:

     SELECT s1 FROM t1 WHERE s1 > ALL (SELECT s1 FROM t2);

Suppose that there is a row in table `t1' containing `(10)'. The
expression is `TRUE' if table `t2' contains `(-5,0,+5)' because `10' is
greater than all three values in `t2'. The expression is `FALSE' if
table `t2' contains `(12,6,NULL,-100)' because there is a single value
`12' in table `t2' that is greater than `10'. The expression is
_unknown_ (that is, `NULL') if table `t2' contains `(0,NULL,1)'.

Finally, if table `t2' is empty, the result is `TRUE'. So, the
following statement is `TRUE' when table `t2' is empty:

     SELECT * FROM t1 WHERE 1 > ALL (SELECT s1 FROM t2);

But this statement is `NULL' when table `t2' is empty:

     SELECT * FROM t1 WHERE 1 > (SELECT s1 FROM t2);

In addition, the following statement is `NULL' when table `t2' is empty:

     SELECT * FROM t1 WHERE 1 > ALL (SELECT MAX(s1) FROM t2);

In general, _tables containing `NULL' values_ and _empty tables_ are
`edge cases.' When writing subquery code, always consider whether you
have taken those two possibilities into account.

`NOT IN' is an alias for `<> ALL'. Thus, these two statements are the
same:

     SELECT s1 FROM t1 WHERE s1 <> ALL (SELECT s1 FROM t2);
     SELECT s1 FROM t1 WHERE s1 NOT IN (SELECT s1 FROM t2);


File: manual.info,  Node: row-subqueries,  Next: exists-and-not-exists-subqueries,  Prev: all-subqueries,  Up: subqueries

12.2.10.5 Row Subqueries
........................

The discussion to this point has been of scalar or column subqueries;
that is, subqueries that return a single value or a column of values. A
_row subquery_ is a subquery variant that returns a single row and can
thus return more than one column value. Legal operators for row subquery
comparisons are:

     =  >  <  >=  <=  <>  !=  <=>

Here are two examples:

     SELECT * FROM t1 WHERE (1,2) = (SELECT column1, column2 FROM t2);
     SELECT * FROM t1 WHERE ROW(1,2) = (SELECT column1, column2 FROM t2);

The queries here are both `TRUE' if table `t2' has a row where `column1
= 1' and `column2 = 2'.

The expressions `(1,2)' and `ROW(1,2)' are sometimes called _row
constructors_. The two are equivalent. The row constructor and the row
returned by the subquery must contain the same number of values.

Row constructors are legal in other contexts as well. For example, the
following two statements are semantically equivalent:

     SELECT * FROM t1 WHERE (column1,column2) = (1,1);
     SELECT * FROM t1 WHERE column1 = 1 AND column2 = 1;

The normal use of row constructors is for comparisons with subqueries
that return two or more columns. For example, the following query
answers the request, `find all rows in table `t1' that also exist in
table `t2'':

     SELECT column1,column2,column3
            FROM t1
            WHERE (column1,column2,column3) IN
                  (SELECT column1,column2,column3 FROM t2);


File: manual.info,  Node: exists-and-not-exists-subqueries,  Next: correlated-subqueries,  Prev: row-subqueries,  Up: subqueries

12.2.10.6 `EXISTS' and `NOT EXISTS'
...................................

If a subquery returns any rows at all, `EXISTS SUBQUERY' is `TRUE', and
`NOT EXISTS SUBQUERY' is `FALSE'. For example:

     SELECT column1 FROM t1 WHERE EXISTS (SELECT * FROM t2);

Traditionally, an `EXISTS' subquery starts with `SELECT *', but it
could begin with `SELECT 5' or `SELECT column1' or anything at all.
MySQL ignores the *Note `SELECT': select. list in such a subquery, so
it makes no difference.

For the preceding example, if `t2' contains any rows, even rows with
nothing but `NULL' values, the `EXISTS' condition is `TRUE'. This is
actually an unlikely example because a `[NOT] EXISTS' subquery almost
always contains correlations. Here are some more realistic examples:

   * What kind of store is present in one or more cities?

          SELECT DISTINCT store_type FROM stores
            WHERE EXISTS (SELECT * FROM cities_stores
                          WHERE cities_stores.store_type = stores.store_type);

   * What kind of store is present in no cities?

          SELECT DISTINCT store_type FROM stores
            WHERE NOT EXISTS (SELECT * FROM cities_stores
                              WHERE cities_stores.store_type = stores.store_type);

   * What kind of store is present in all cities?

          SELECT DISTINCT store_type FROM stores s1
            WHERE NOT EXISTS (
              SELECT * FROM cities WHERE NOT EXISTS (
                SELECT * FROM cities_stores
                 WHERE cities_stores.city = cities.city
                 AND cities_stores.store_type = stores.store_type));

The last example is a double-nested `NOT EXISTS' query. That is, it has
a `NOT EXISTS' clause within a `NOT EXISTS' clause. Formally, it
answers the question `does a city exist with a store that is not in
`Stores''? But it is easier to say that a nested `NOT EXISTS' answers
the question `is X `TRUE' for all Y?'


File: manual.info,  Node: correlated-subqueries,  Next: unnamed-views,  Prev: exists-and-not-exists-subqueries,  Up: subqueries

12.2.10.7 Correlated Subqueries
...............................

A _correlated subquery_ is a subquery that contains a reference to a
table that also appears in the outer query. For example:

     SELECT * FROM t1 WHERE column1 = ANY
            (SELECT column1 FROM t2 WHERE t2.column2 = t1.column2);

Notice that the subquery contains a reference to a column of `t1', even
though the subquery's `FROM' clause does not mention a table `t1'. So,
MySQL looks outside the subquery, and finds `t1' in the outer query.

Suppose that table `t1' contains a row where `column1 = 5' and `column2
= 6'; meanwhile, table `t2' contains a row where `column1 = 5' and
`column2 = 7'. The simple expression `... WHERE column1 = ANY (SELECT
column1 FROM t2)' would be `TRUE', but in this example, the `WHERE'
clause within the subquery is `FALSE' (because `(5,6)' is not equal to
`(5,7)'), so the subquery as a whole is `FALSE'.

*Scoping rule:* MySQL evaluates from inside to outside. For example:

     SELECT column1 FROM t1 AS x
       WHERE x.column1 = (SELECT column1 FROM t2 AS x
         WHERE x.column1 = (SELECT column1 FROM t3
           WHERE x.column2 = t3.column1));

In this statement, `x.column2' must be a column in table `t2' because
`SELECT column1 FROM t2 AS x ...' renames `t2'. It is not a column in
table `t1' because `SELECT column1 FROM t1 ...' is an outer query that
is _farther out_.

For subqueries in `HAVING' or `ORDER BY' clauses, MySQL also looks for
column names in the outer select list.

For certain cases, a correlated subquery is optimized. For example:

     VAL IN (SELECT KEY_VAL FROM TBL_NAME WHERE CORRELATED_CONDITION)

Otherwise, they are inefficient and likely to be slow. Rewriting the
query as a join might improve performance.

Aggregate functions in correlated subqueries may contain outer
references, provided the function contains nothing but outer
references, and provided the function is not contained in another
function or expression.


File: manual.info,  Node: unnamed-views,  Next: subquery-errors,  Prev: correlated-subqueries,  Up: subqueries

12.2.10.8 Subqueries in the `FROM' clause
.........................................

Subqueries are legal in a *Note `SELECT': select.  statement's `FROM'
clause. The actual syntax is:

     SELECT ... FROM (SUBQUERY) [AS] NAME ...

The `[AS] NAME' clause is mandatory, because every table in a `FROM'
clause must have a name. Any columns in the SUBQUERY select list must
have unique names.

For the sake of illustration, assume that you have this table:

     CREATE TABLE t1 (s1 INT, s2 CHAR(5), s3 FLOAT);

Here is how to use a subquery in the `FROM' clause, using the example
table:

     INSERT INTO t1 VALUES (1,'1',1.0);
     INSERT INTO t1 VALUES (2,'2',2.0);
     SELECT sb1,sb2,sb3
            FROM (SELECT s1 AS sb1, s2 AS sb2, s3*2 AS sb3 FROM t1) AS sb
            WHERE sb1 > 1;

Result: `2, '2', 4.0'.

Here is another example: Suppose that you want to know the average of a
set of sums for a grouped table. This does not work:

     SELECT AVG(SUM(column1)) FROM t1 GROUP BY column1;

However, this query provides the desired information:

     SELECT AVG(sum_column1)
            FROM (SELECT SUM(column1) AS sum_column1
                  FROM t1 GROUP BY column1) AS t1;

Notice that the column name used within the subquery (`sum_column1') is
recognized in the outer query.

Subqueries in the `FROM' clause can return a scalar, column, row, or
table. Subqueries in the `FROM' clause cannot be correlated subqueries,
unless used within the `ON' clause of a `JOIN' operation.

Subqueries in the `FROM' clause are executed even for the *Note
`EXPLAIN': explain. statement (that is, derived temporary tables are
built). This occurs because upper-level queries need information about
all tables during the optimization phase, and the table represented by a
subquery in the `FROM' clause is unavailable unless the subquery is
executed.

It is also possible under certain circumstances to modify table data
using *Note `EXPLAIN SELECT': explain. This can occur if the outer
query accesses any tables and an inner query invokes a stored function
that changes one or more rows of a table. For example, suppose there
are two tables `t1' and `t2' in database `d1', created as shown here:

     mysql> CREATE DATABASE d1;
     Query OK, 1 row affected (0.00 sec)

     mysql> USE d1;
     Database changed

     mysql> CREATE TABLE t1 (c1 INT);
     Query OK, 0 rows affected (0.15 sec)

     mysql> CREATE TABLE t2 (c1 INT);
     Query OK, 0 rows affected (0.08 sec)

Now we create a stored function `f1' which modifies `t2':

     mysql> DELIMITER //
     mysql> CREATE FUNCTION f1(p1 INT) RETURNS INT
     mysql>   BEGIN
     mysql>     INSERT INTO t2 VALUES (p1);
     mysql>     RETURN p1;
     mysql>   END //
     Query OK, 0 rows affected (0.01 sec)

     mysql> DELIMITER ;

Referencing the function directly in an *Note `EXPLAIN SELECT':
explain. does not have any effect on `t2', as shown here:

     mysql> SELECT * FROM t2;
     Empty set (0.00 sec)

     mysql> EXPLAIN SELECT f1(5);
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     | id | select_type | table | type | possible_keys | key  | key_len | ref  | rows | Extra          |
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     |  1 | SIMPLE      | NULL  | NULL | NULL          | NULL | NULL    | NULL | NULL | No tables used |
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     1 row in set (0.00 sec)

     mysql> SELECT * FROM t2;
     Empty set (0.00 sec)

This is because the *Note `SELECT': select.  statement did not
reference any tables, as can be seen in the `table' and `Extra' columns
of the output. This is also true of the following nested *Note
`SELECT': select.:

     mysql> EXPLAIN SELECT NOW() AS a1, (SELECT f1(5)) AS a2;
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     | id | select_type | table | type | possible_keys | key  | key_len | ref  | rows | Extra          |
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     |  1 | PRIMARY     | NULL  | NULL | NULL          | NULL | NULL    | NULL | NULL | No tables used |
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     1 row in set, 1 warning (0.00 sec)

     mysql> SHOW WARNINGS;
     +-------+------+------------------------------------------+
     | Level | Code | Message                                  |
     +-------+------+------------------------------------------+
     | Note  | 1249 | Select 2 was reduced during optimization |
     +-------+------+------------------------------------------+
     1 row in set (0.00 sec)

     mysql> SELECT * FROM t2;
     Empty set (0.00 sec)

However, if the outer *Note `SELECT': select.  references any tables,
then the optimizer executes the statement in the subquery as well:

     mysql> EXPLAIN SELECT * FROM t1 AS a1, (SELECT f1(5)) AS a2;
     +----+-------------+------------+--------+---------------+------+---------+------+------+---------------------+
     | id | select_type | table      | type   | possible_keys | key  | key_len | ref  | rows | Extra               |
     +----+-------------+------------+--------+---------------+------+---------+------+------+---------------------+
     |  1 | PRIMARY     | a1         | system | NULL          | NULL | NULL    | NULL |    0 | const row not found |
     |  1 | PRIMARY     | <derived2> | system | NULL          | NULL | NULL    | NULL |    1 |                     |
     |  2 | DERIVED     | NULL       | NULL   | NULL          | NULL | NULL    | NULL | NULL | No tables used      |
     +----+-------------+------------+--------+---------------+------+---------+------+------+---------------------+
     3 rows in set (0.00 sec)

     mysql> SELECT * FROM t2;
     +------+
     | c1   |
     +------+
     |    5 |
     +------+
     1 row in set (0.00 sec)

This also means that an *Note `EXPLAIN SELECT': explain. statement such
as the one shown here may take a long time to execute:

     EXPLAIN SELECT * FROM t1 AS a1, (SELECT BENCHMARK(1000000, MD5(NOW())));

This is because the `BENCHMARK()' function is executed once for each
row in `t1'.


File: manual.info,  Node: subquery-errors,  Next: optimizing-subqueries,  Prev: unnamed-views,  Up: subqueries

12.2.10.9 Subquery Errors
.........................

There are some errors that apply only to subqueries. This section
describes them.

   * Unsupported subquery syntax:

          ERROR 1235 (ER_NOT_SUPPORTED_YET)
          SQLSTATE = 42000
          Message = "This version of MySQL does not yet support
          'LIMIT & IN/ALL/ANY/SOME subquery'"

     This means that statements of the following form do not work yet:

          SELECT * FROM t1 WHERE s1 IN (SELECT s2 FROM t2 ORDER BY s1 LIMIT 1)

   * Incorrect number of columns from subquery:

          ERROR 1241 (ER_OPERAND_COL)
          SQLSTATE = 21000
          Message = "Operand should contain 1 column(s)"

     This error occurs in cases like this:

          SELECT (SELECT column1, column2 FROM t2) FROM t1;

     You may use a subquery that returns multiple columns, if the
     purpose is comparison. In other contexts, the subquery must be a
     scalar operand. See *Note row-subqueries::.

   * Incorrect number of rows from subquery:

          ERROR 1242 (ER_SUBSELECT_NO_1_ROW)
          SQLSTATE = 21000
          Message = "Subquery returns more than 1 row"

     This error occurs for statements where the subquery returns more
     than one row. Consider the following example:

          SELECT * FROM t1 WHERE column1 = (SELECT column1 FROM t2);

     If `SELECT column1 FROM t2' returns just one row, the previous
     query will work. If the subquery returns more than one row, error
     1242 will occur. In that case, the query should be rewritten as:

          SELECT * FROM t1 WHERE column1 = ANY (SELECT column1 FROM t2);

   * Incorrectly used table in subquery:

          Error 1093 (ER_UPDATE_TABLE_USED)
          SQLSTATE = HY000
          Message = "You can't specify target table 'x'
          for update in FROM clause"

     This error occurs in cases such as the following:

          UPDATE t1 SET column2 = (SELECT MAX(column1) FROM t1);

     You can use a subquery for assignment within an *Note `UPDATE':
     update. statement because subqueries are legal in *Note `UPDATE':
     update. and *Note `DELETE': delete. statements as well as in *Note
     `SELECT': select. statements.  However, you cannot use the same
     table (in this case, table `t1') for both the subquery's `FROM'
     clause and the update target.

For transactional storage engines, the failure of a subquery causes the
entire statement to fail. For non-transactional storage engines, data
modifications made before the error was encountered are preserved.


File: manual.info,  Node: optimizing-subqueries,  Next: rewriting-subqueries,  Prev: subquery-errors,  Up: subqueries

12.2.10.10 Optimizing Subqueries
................................

Development is ongoing, so no optimization tip is reliable for the long
term. The following list provides some interesting tricks that you
might want to play with:

   * Use subquery clauses that affect the number or order of the rows
     in the subquery. For example:

          SELECT * FROM t1 WHERE t1.column1 IN
            (SELECT column1 FROM t2 ORDER BY column1);
          SELECT * FROM t1 WHERE t1.column1 IN
            (SELECT DISTINCT column1 FROM t2);
          SELECT * FROM t1 WHERE EXISTS
            (SELECT * FROM t2 LIMIT 1);

   * Replace a join with a subquery. For example, try this:

          SELECT DISTINCT column1 FROM t1 WHERE t1.column1 IN (
            SELECT column1 FROM t2);

     Instead of this:

          SELECT DISTINCT t1.column1 FROM t1, t2
            WHERE t1.column1 = t2.column1;

   * Some subqueries can be transformed to joins for compatibility with
     older versions of MySQL that do not support subqueries. However,
     in some cases, converting a subquery to a join may improve
     performance. See *Note rewriting-subqueries::.

   * Move clauses from outside to inside the subquery. For example, use
     this query:

          SELECT * FROM t1
            WHERE s1 IN (SELECT s1 FROM t1 UNION ALL SELECT s1 FROM t2);

     Instead of this query:

          SELECT * FROM t1
            WHERE s1 IN (SELECT s1 FROM t1) OR s1 IN (SELECT s1 FROM t2);

     For another example, use this query:

          SELECT (SELECT column1 + 5 FROM t1) FROM t2;

     Instead of this query:

          SELECT (SELECT column1 FROM t1) + 5 FROM t2;

   * Use a row subquery instead of a correlated subquery. For example,
     use this query:

          SELECT * FROM t1
            WHERE (column1,column2) IN (SELECT column1,column2 FROM t2);

     Instead of this query:

          SELECT * FROM t1
            WHERE EXISTS (SELECT * FROM t2 WHERE t2.column1=t1.column1
            AND t2.column2=t1.column2);

   * Use `NOT (a = ANY (...))' rather than `a <> ALL (...)'.

   * Use `x = ANY (TABLE CONTAINING (1,2))' rather than `x=1 OR x=2'.

   * Use `= ANY' rather than `EXISTS'.

   * For uncorrelated subqueries that always return one row, `IN' is
     always slower than `='. For example, use this query:

          SELECT * FROM t1 WHERE t1.COL_NAME
            = (SELECT a FROM t2 WHERE b = SOME_CONST);

     Instead of this query:

          SELECT * FROM t1 WHERE t1.COL_NAME
            IN (SELECT a FROM t2 WHERE b = SOME_CONST);

These tricks might cause programs to go faster or slower. Using MySQL
facilities like the `BENCHMARK()' function, you can get an idea about
what helps in your own situation. See *Note information-functions::.

Some optimizations that MySQL itself makes are:

   * MySQL executes uncorrelated subqueries only once. Use *Note
     `EXPLAIN': explain. to make sure that a given subquery really is
     uncorrelated.

   * MySQL rewrites `IN', `ALL', `ANY', and `SOME' subqueries in an
     attempt to take advantage of the possibility that the select-list
     columns in the subquery are indexed.

   * MySQL replaces subqueries of the following form with an
     index-lookup function, which *Note `EXPLAIN': explain. describes
     as a special join type (`unique_subquery' or `index_subquery'):

          ... IN (SELECT INDEXED_COLUMN FROM SINGLE_TABLE ...)

   * MySQL enhances expressions of the following form with an
     expression involving `MIN()' or `MAX()', unless `NULL' values or
     empty sets are involved:

          VALUE {ALL|ANY|SOME} {> | < | >= | <=} (UNCORRELATED SUBQUERY)

     For example, this `WHERE' clause:

          WHERE 5 > ALL (SELECT x FROM t)

     might be treated by the optimizer like this:

          WHERE 5 > (SELECT MAX(x) FROM t)

See also the MySQL Internals Manual chapter How MySQL Transforms
Subqueries
(http://forge.mysql.com/wiki/MySQL_Internals_Transformations).


File: manual.info,  Node: rewriting-subqueries,  Prev: optimizing-subqueries,  Up: subqueries

12.2.10.11 Rewriting Subqueries as Joins
........................................

Although MySQL 6.0 supports subqueries (see *Note subqueries::), it is
still true that there are sometimes other ways to test membership in a
set of values. It is also true that on some occasions, it is not only
possible to rewrite a query without a subquery, but it can be more
efficient to make use of some of these techniques rather than to use
subqueries. One of these is the `IN()' construct:

For example, this query:

     SELECT * FROM t1 WHERE id IN (SELECT id FROM t2);

Can be rewritten as:

     SELECT DISTINCT t1.* FROM t1, t2 WHERE t1.id=t2.id;

The queries:

     SELECT * FROM t1 WHERE id NOT IN (SELECT id FROM t2);
     SELECT * FROM t1 WHERE NOT EXISTS (SELECT id FROM t2 WHERE t1.id=t2.id);

Can be rewritten as:

     SELECT table1.*
       FROM table1 LEFT JOIN table2 ON table1.id=table2.id
       WHERE table2.id IS NULL;

A `LEFT [OUTER] JOIN' can be faster than an equivalent subquery because
the server might be able to optimize it better -- a fact that is not
specific to MySQL Server alone. Prior to SQL-92, outer joins did not
exist, so subqueries were the only way to do certain things. Today,
MySQL Server and many other modern database systems offer a wide range
of outer join types.

MySQL Server supports multiple-table *Note `DELETE': delete. statements
that can be used to efficiently delete rows based on information from
one table or even from many tables at the same time. Multiple-table
*Note `UPDATE': update. statements are also supported. See *Note
delete::, and *Note update::.


File: manual.info,  Node: truncate,  Next: update,  Prev: subqueries,  Up: sql-syntax-data-manipulation

12.2.11 `TRUNCATE' Syntax
-------------------------

     TRUNCATE [TABLE] TBL_NAME

*Note `TRUNCATE TABLE': truncate.  empties a table completely.
Logically, this is equivalent to a *Note `DELETE': delete. statement
that deletes all rows, but there are practical differences under some
circumstances.

For an `InnoDB' table, `InnoDB' processes *Note `TRUNCATE TABLE':
truncate. by deleting rows one by one if there are any `FOREIGN KEY'
constraints that reference the table. If there are no `FOREIGN KEY'
constraints, `InnoDB' performs fast truncation by dropping the original
table and creating an empty one with the same definition, which is much
faster than deleting rows one by one. The `AUTO_INCREMENT' counter is
reset by *Note `TRUNCATE TABLE': truncate, regardless of whether there
is a `FOREIGN KEY' constraint.

In the case that `FOREIGN KEY' constraints reference the table,
`InnoDB' deletes rows one by one and processes the constraints on each
one. If the `FOREIGN KEY' constraint specifies `DELETE CASCADE', rows
from the child (referenced) table are deleted, and the truncated table
becomes empty. If the `FOREIGN KEY' constraint does _not_ specify
`CASCADE', the *Note `TRUNCATE': truncate. statement deletes rows one
by one and stops if it encounters a parent row that is referenced by
the child, returning this error:

     ERROR 1451 (23000): Cannot delete or update a parent row: a foreign
     key constraint fails (`test`.`child`, CONSTRAINT `child_ibfk_1`
     FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`))

This is the same as a *Note `DELETE': delete.  statement with no
`WHERE' clause.

Beginning with MySQL 6.0.10, *Note `TRUNCATE': truncate. is treated for
purposes of binary logging and replication as *Note `DROP TABLE':
drop-table. followed by *Note `CREATE TABLE': create-table. -- that is,
as DDL rather than DML. This is due to the fact that, when using
`InnoDB' and other transactional storage engines where the transaction
isolation level does not allow for statement-based logging (`READ
COMMITTED' or `READ UNCOMMITTED'), the statement was not logged and
replicated when using `STATEMENT' or `MIXED' logging mode. (Bug#36763
(http://bugs.mysql.com/36763)) However, it is still applied on
replication slaves using `InnoDB' in the manner described previously.

The count of rows affected by *Note `TRUNCATE TABLE': truncate.  is
accurate only when it is mapped to a *Note `DELETE': delete. statement.

For other storage engines, *Note `TRUNCATE TABLE': truncate.  differs
from *Note `DELETE': delete. in the following ways in MySQL 6.0:

   * Truncate operations drop and re-create the table, which is much
     faster than deleting rows one by one, particularly for large
     tables.

   * Truncate operations are not transaction-safe; an error occurs when
     attempting one in the course of an active transaction or active
     table lock.

   * Truncation operations do not return the number of deleted rows.

   * As long as the table format file `TBL_NAME.frm' is valid, the
     table can be re-created as an empty table with *Note `TRUNCATE
     TABLE': truncate, even if the data or index files have become
     corrupted.

   * The table handler does not remember the last used `AUTO_INCREMENT'
     value, but starts counting from the beginning. This is true even
     for `MyISAM' and `InnoDB', which normally do not reuse sequence
     values.

   * When used with partitioned tables, *Note `TRUNCATE TABLE':
     truncate. preserves the partitioning; that is, the data and index
     files are dropped and re-created, while the partition definitions
     (`.par') file is unaffected.

   * Since truncation of a table does not make any use of *Note
     `DELETE': delete, the *Note `TRUNCATE': truncate. statement does
     not invoke `ON DELETE' triggers.

*Note `TRUNCATE TABLE': truncate.  requires the `DROP' privilege.


File: manual.info,  Node: update,  Prev: truncate,  Up: sql-syntax-data-manipulation

12.2.12 `UPDATE' Syntax
-----------------------

Single-table syntax:

     UPDATE [LOW_PRIORITY] [IGNORE] TABLE_REFERENCE
         SET COL_NAME1={EXPR1|DEFAULT} [, COL_NAME2={EXPR2|DEFAULT}] ...
         [WHERE WHERE_CONDITION]
         [ORDER BY ...]
         [LIMIT ROW_COUNT]

Multiple-table syntax:

     UPDATE [LOW_PRIORITY] [IGNORE] TABLE_REFERENCES
         SET COL_NAME1={EXPR1|DEFAULT} [, COL_NAME2={EXPR2|DEFAULT}] ...
         [WHERE WHERE_CONDITION]

For the single-table syntax, the *Note `UPDATE': update. statement
updates columns of existing rows in the named table with new values. The
`SET' clause indicates which columns to modify and the values they
should be given. Each value can be given as an expression, or the
keyword `DEFAULT' to set a column explicitly to its default value. The
`WHERE' clause, if given, specifies the conditions that identify which
rows to update. With no `WHERE' clause, all rows are updated. If the
`ORDER BY' clause is specified, the rows are updated in the order that
is specified. The `LIMIT' clause places a limit on the number of rows
that can be updated.

For the multiple-table syntax, *Note `UPDATE': update. updates rows in
each table named in TABLE_REFERENCES that satisfy the conditions. In
this case, `ORDER BY' and `LIMIT' cannot be used.

WHERE_CONDITION is an expression that evaluates to true for each row to
be updated.

TABLE_REFERENCES and WHERE_CONDITION are is specified as described in
*Note select::.

The *Note `UPDATE': update. statement supports the following modifiers:

   * If you use the `LOW_PRIORITY' keyword, execution of the *Note
     `UPDATE': update. is delayed until no other clients are reading
     from the table.  This affects only storage engines that use only
     table-level locking (`MyISAM', `MEMORY', `MERGE').

   * If you use the `IGNORE' keyword, the update statement does not
     abort even if errors occur during the update. Rows for which
     duplicate-key conflicts occur are not updated. Rows for which
     columns are updated to values that would cause data conversion
     errors are updated to the closest valid values instead.

If you access a column from the table to be updated in an expression,
*Note `UPDATE': update. uses the current value of the column. For
example, the following statement sets the `age' column to one more than
its current value:

     UPDATE persondata SET age=age+1;

Single-table *Note `UPDATE': update. assignments are generally
evaluated from left to right. For multiple-table updates, there is no
guarantee that assignments are carried out in any particular order.

If you set a column to the value it currently has, MySQL notices this
and does not update it.

If you update a column that has been declared `NOT NULL' by setting to
`NULL', an error occurs if strict SQL mode is enabled; otherwise, the
column is set to the implicit default value for the column data type
and the warning count is incremented. The implicit default value is `0'
for numeric types, the empty string (`''') for string types, and the
`zero' value for date and time types. See *Note data-type-defaults::.

*Note `UPDATE': update. returns the number of rows that were actually
changed. The *Note `mysql_info()': mysql-info. C API function returns
the number of rows that were matched and updated and the number of
warnings that occurred during the *Note `UPDATE': update.

You can use `LIMIT ROW_COUNT' to restrict the scope of the *Note
`UPDATE': update. A `LIMIT' clause is a rows-matched restriction. The
statement stops as soon as it has found ROW_COUNT rows that satisfy the
`WHERE' clause, whether or not they actually were changed.

If an *Note `UPDATE': update. statement includes an `ORDER BY' clause,
the rows are updated in the order specified by the clause. This can be
useful in certain situations that might otherwise result in an error.
Suppose that a table `t' contains a column `id' that has a unique
index. The following statement could fail with a duplicate-key error,
depending on the order in which rows are updated:

     UPDATE t SET id = id + 1;

For example, if the table contains 1 and 2 in the `id' column and 1 is
updated to 2 before 2 is updated to 3, an error occurs. To avoid this
problem, add an `ORDER BY' clause to cause the rows with larger `id'
values to be updated before those with smaller values:

     UPDATE t SET id = id + 1 ORDER BY id DESC;

You can also perform *Note `UPDATE': update.  operations covering
multiple tables. However, you cannot use `ORDER BY' or `LIMIT' with a
multiple-table *Note `UPDATE': update. The TABLE_REFERENCES clause
lists the tables involved in the join. Its syntax is described in *Note
join::. Here is an example:

     UPDATE items,month SET items.price=month.price
     WHERE items.id=month.id;

The preceding example shows an inner join that uses the comma operator,
but multiple-table *Note `UPDATE': update.  statements can use any type
of join allowed in *Note `SELECT': select. statements, such as `LEFT
JOIN'.

You need the `UPDATE' privilege only for columns referenced in a
multiple-table *Note `UPDATE': update. that are actually updated.  You
need only the `SELECT' privilege for any columns that are read but not
modified.

If you use a multiple-table *Note `UPDATE': update.  statement
involving `InnoDB' tables for which there are foreign key constraints,
the MySQL optimizer might process tables in an order that differs from
that of their parent/child relationship. In this case, the statement
fails and rolls back. Instead, update a single table and rely on the
`ON UPDATE' capabilities that `InnoDB' provides to cause the other
tables to be modified accordingly. See *Note
innodb-foreign-key-constraints::.

Currently, you cannot update a table and select from the same table in
a subquery.

Index hints (see *Note index-hints::) are accepted but ignored for
*Note `UPDATE': update. statements.


File: manual.info,  Node: sql-syntax-utility,  Next: sql-syntax-transactions,  Prev: sql-syntax-data-manipulation,  Up: sql-syntax

12.3 MySQL Utility Statements
=============================

* Menu:

* describe::                     `DESCRIBE' Syntax
* explain::                      `EXPLAIN' Syntax
* help::                         `HELP' Syntax
* use::                          `USE' Syntax


File: manual.info,  Node: describe,  Next: explain,  Prev: sql-syntax-utility,  Up: sql-syntax-utility

12.3.1 `DESCRIBE' Syntax
------------------------

     {DESCRIBE | DESC} TBL_NAME [COL_NAME | WILD]

*Note `DESCRIBE': describe. provides information about the columns in a
table. It is a shortcut for `SHOW COLUMNS FROM'. These statements also
display information for views. (See *Note show-columns::.)

COL_NAME can be a column name, or a string containing the SQL ``%'' and
``_'' wildcard characters to obtain output only for the columns with
names matching the string. There is no need to enclose the string
within quotes unless it contains spaces or other special characters.

     mysql> DESCRIBE City;
     +------------+----------+------+-----+---------+----------------+
     | Field      | Type     | Null | Key | Default | Extra          |
     +------------+----------+------+-----+---------+----------------+
     | Id         | int(11)  | NO   | PRI | NULL    | auto_increment |
     | Name       | char(35) | NO   |     |         |                |
     | Country    | char(3)  | NO   | UNI |         |                |
     | District   | char(20) | YES  | MUL |         |                |
     | Population | int(11)  | NO   |     | 0       |                |
     +------------+----------+------+-----+---------+----------------+
     5 rows in set (0.00 sec)

The description for *Note `SHOW COLUMNS': show-columns.  provides more
information about the output columns (see *Note show-columns::).

The *Note `DESCRIBE': describe. statement is provided for compatibility
with Oracle.

The *Note `SHOW CREATE TABLE': show-create-table, *Note `SHOW TABLE
STATUS': show-table-status, and *Note `SHOW INDEX': show-index.
statements also provide information about tables. See *Note show::.


File: manual.info,  Node: explain,  Next: help,  Prev: describe,  Up: sql-syntax-utility

12.3.2 `EXPLAIN' Syntax
-----------------------

     EXPLAIN TBL_NAME

Or:

     EXPLAIN [EXTENDED | PARTITIONS] SELECT SELECT_OPTIONS

The *Note `EXPLAIN': explain. statement can be used either as a synonym
for *Note `DESCRIBE': describe. or as a way to obtain information about
how MySQL executes a *Note `SELECT': select. statement:

   * `EXPLAIN TBL_NAME' is synonymous with `DESCRIBE TBL_NAME' or `SHOW
     COLUMNS FROM TBL_NAME'.

     For a description of the *Note `DESCRIBE': describe. and *Note
     `SHOW COLUMNS': show-columns. statements, see *Note describe::, and
     *Note show-columns::.

   * When you precede a *Note `SELECT': select.  statement with the
     keyword *Note `EXPLAIN': explain, MySQL displays information from
     the optimizer about the query execution plan.  That is, MySQL
     explains how it would process the *Note `SELECT': select,
     including information about how tables are joined and in which
     order.  `EXPLAIN EXTENDED' can be used to provide additional
     information.

     For information regarding the use of *Note `EXPLAIN': explain. and
     `EXPLAIN EXTENDED' for obtaining query execution plan information,
     see *Note using-explain::.

   * `EXPLAIN PARTITIONS' is available beginning with MySQL 5.1.5. It
     is useful only when examining queries involving partitioned tables.

     For details, see *Note partitioning-info::.


File: manual.info,  Node: help,  Next: use,  Prev: explain,  Up: sql-syntax-utility

12.3.3 `HELP' Syntax
--------------------

     HELP 'SEARCH_STRING'

The *Note `HELP': help. statement returns online information from the
MySQL Reference manual. Its proper operation requires that the help
tables in the `mysql' database be initialized with help topic
information (see *Note server-side-help-support::).

The *Note `HELP': help. statement searches the help tables for the
given search string and displays the result of the search. The search
string is not case sensitive.

The HELP statement understands several types of search strings:

   * At the most general level, use `contents' to retrieve a list of
     the top-level help categories:

          HELP 'contents'

   * For a list of topics in a given help category, such as `Data
     Types', use the category name:

          HELP 'data types'

   * For help on a specific help topic, such as the `ASCII()' function
     or the *Note `CREATE TABLE': create-table. statement, use the
     associated keyword or keywords:

          HELP 'ascii'
          HELP 'create table'

In other words, the search string matches a category, many topics, or a
single topic. You cannot necessarily tell in advance whether a given
search string will return a list of items or the help information for a
single help topic. However, you can tell what kind of response *Note
`HELP': help. returned by examining the number of rows and columns in
the result set.

The following descriptions indicate the forms that the result set can
take. Output for the example statements is shown using the familiar
`tabular' or `vertical' format that you see when using the *Note
`mysql': mysql. client, but note that *Note `mysql': mysql. itself
reformats *Note `HELP': help. result sets in a different way.

   * Empty result set

     No match could be found for the search string.

   * Result set containing a single row with three columns

     This means that the search string yielded a hit for the help
     topic. The result has three columns:

        * `name': The topic name.

        * `description': Descriptive help text for the topic.

        * `example': Usage example or examples.  This column might be
          blank.

     Example: `HELP 'replace''

     Yields:

          name: REPLACE
          description: Syntax:
          REPLACE(str,from_str,to_str)

          Returns the string str with all occurrences of the string from_str
          replaced by the string to_str. REPLACE() performs a case-sensitive
          match when searching for from_str.
          example: mysql> SELECT REPLACE('www.mysql.com', 'w', 'Ww');
                  -> 'WwWwWw.mysql.com'

   * Result set containing multiple rows with two columns

     This means that the search string matched many help topics.  The
     result set indicates the help topic names:

        * `name': The help topic name.

        * `is_it_category': `Y' if the name represents a help category,
          `N' if it does not. If it does not, the `name' value when
          specified as the argument to the *Note `HELP': help.
          statement should yield a single-row result set containing a
          description for the named item.

     Example: `HELP 'status''

     Yields:

          +-----------------------+----------------+
          | name                  | is_it_category |
          +-----------------------+----------------+
          | SHOW                  | N              |
          | SHOW ENGINE           | N              |
          | SHOW MASTER STATUS    | N              |
          | SHOW PROCEDURE STATUS | N              |
          | SHOW SLAVE STATUS     | N              |
          | SHOW STATUS           | N              |
          | SHOW TABLE STATUS     | N              |
          +-----------------------+----------------+

   * Result set containing multiple rows with three columns

     This means the search string matches a category. The result set
     contains category entries:

        * `source_category_name': The help category name.

        * `name': The category or topic name

        * `is_it_category': `Y' if the name represents a help category,
          `N' if it does not. If it does not, the `name' value when
          specified as the argument to the *Note `HELP': help.
          statement should yield a single-row result set containing a
          description for the named item.

     Example: `HELP 'functions''

     Yields:

          +----------------------+-------------------------+----------------+
          | source_category_name | name                    | is_it_category |
          +----------------------+-------------------------+----------------+
          | Functions            | CREATE FUNCTION         | N              |
          | Functions            | DROP FUNCTION           | N              |
          | Functions            | Bit Functions           | Y              |
          | Functions            | Comparison operators    | Y              |
          | Functions            | Control flow functions  | Y              |
          | Functions            | Date and Time Functions | Y              |
          | Functions            | Encryption Functions    | Y              |
          | Functions            | Information Functions   | Y              |
          | Functions            | Logical operators       | Y              |
          | Functions            | Miscellaneous Functions | Y              |
          | Functions            | Numeric Functions       | Y              |
          | Functions            | String Functions        | Y              |
          +----------------------+-------------------------+----------------+


File: manual.info,  Node: use,  Prev: help,  Up: sql-syntax-utility

12.3.4 `USE' Syntax
-------------------

     USE DB_NAME

The `USE DB_NAME' statement tells MySQL to use the DB_NAME database as
the default (current) database for subsequent statements. The database
remains the default until the end of the session or another *Note
`USE': use. statement is issued:

     USE db1;
     SELECT COUNT(*) FROM mytable;   # selects from db1.mytable
     USE db2;
     SELECT COUNT(*) FROM mytable;   # selects from db2.mytable

Making a particular database the default by means of the *Note `USE':
use. statement does not preclude you from accessing tables in other
databases. The following example accesses the `author' table from the
`db1' database and the `editor' table from the `db2' database:

     USE db1;
     SELECT author_name,editor_name FROM author,db2.editor
       WHERE author.editor_id = db2.editor.editor_id;

The *Note `USE': use. statement is provided for compatibility with
Sybase.


File: manual.info,  Node: sql-syntax-transactions,  Next: sql-syntax-server-administration,  Prev: sql-syntax-utility,  Up: sql-syntax

12.4 MySQL Transactional and Locking Statements
===============================================

* Menu:

* commit::                       `START TRANSACTION', `COMMIT', and `ROLLBACK' Syntax
* cannot-roll-back::             Statements That Cannot Be Rolled Back
* implicit-commit::              Statements That Cause an Implicit Commit
* savepoint::                    `SAVEPOINT' and `ROLLBACK TO SAVEPOINT' Syntax
* lock-tables::                  `LOCK TABLES' and `UNLOCK TABLES' Syntax
* set-transaction::              `SET TRANSACTION' Syntax
* xa::                           XA Transactions

MySQL supports local transactions (within a given client session)
through statements such as *Note `SET autocommit': commit, *Note `START
TRANSACTION': commit, *Note `COMMIT': commit, and *Note `ROLLBACK':
commit. See *Note commit::. XA transaction support enables MySQL to
participate in distributed transactions as well. See *Note xa::.


File: manual.info,  Node: commit,  Next: cannot-roll-back,  Prev: sql-syntax-transactions,  Up: sql-syntax-transactions

12.4.1 `START TRANSACTION', `COMMIT', and `ROLLBACK' Syntax
-----------------------------------------------------------

     START TRANSACTION [WITH CONSISTENT SNAPSHOT] | BEGIN [WORK]
     COMMIT [WORK] [AND [NO] CHAIN] [[NO] RELEASE]
     ROLLBACK [WORK] [AND [NO] CHAIN] [[NO] RELEASE]
     SET autocommit = {0 | 1}

The *Note `START TRANSACTION': commit. or *Note `BEGIN': commit.
statement begins a new transaction. *Note `COMMIT': commit.  commits
the current transaction, making its changes permanent.  *Note
`ROLLBACK': commit. rolls back the current transaction, canceling its
changes. The *Note `SET autocommit': commit.  statement disables or
enables the default autocommit mode for the current session.

The optional `WORK' keyword is supported for *Note `COMMIT': commit. and
*Note `ROLLBACK': commit, as are the `CHAIN' and `RELEASE' clauses.
`CHAIN' and `RELEASE' can be used for additional control over
transaction completion.  The value of the `completion_type' system
variable determines the default completion behavior. See *Note
server-system-variables::.

The `AND CHAIN' clause causes a new transaction to begin as soon as the
current one ends, and the new transaction has the same isolation level
as the just-terminated transaction.  The `RELEASE' clause causes the
server to disconnect the current client session after terminating the
current transaction. Including the `NO' keyword suppresses `CHAIN' or
`RELEASE' completion, which can be useful if the `completion_type'
system variable is set to cause chaining or release completion by
default.

By default, MySQL runs with autocommit mode enabled. This means that as
soon as you execute a statement that updates (modifies) a table, MySQL
stores the update on disk to make it permanent. To disable autocommit
mode, use the following statement:

     SET autocommit=0;

After disabling autocommit mode by setting the `autocommit' variable to
zero, changes to transaction-safe tables (such as those for `InnoDB' or
`NDBCLUSTER') are not made permanent immediately. You must use *Note
`COMMIT': commit. to store your changes to disk or *Note `ROLLBACK':
commit. to ignore the changes.

To disable autocommit mode for a single series of statements, use the
*Note `START TRANSACTION': commit. statement:

*Note*:

The `NDBCLUSTER' storage engine is currently not supported in MySQL
6.0. If you are interested in using MySQL Cluster, see MySQL Cluster
NDB 6.X/7.X
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html), which
provides information about MySQL Cluster NDB 6.2 and 6.3 (based on MySQL
5.1 but containing the latest improvements and fixes for `NDBCLUSTER').

     START TRANSACTION;
     SELECT @A:=SUM(salary) FROM table1 WHERE type=1;
     UPDATE table2 SET summary=@A WHERE type=1;
     COMMIT;

With *Note `START TRANSACTION': commit, autocommit remains disabled
until you end the transaction with *Note `COMMIT': commit. or *Note
`ROLLBACK': commit. The autocommit mode then reverts to its previous
state.

*Note `BEGIN': commit. and *Note `BEGIN WORK': commit. are supported as
aliases of *Note `START TRANSACTION': commit. for initiating a
transaction.  *Note `START TRANSACTION': commit. is standard SQL syntax
and is the recommended way to start an ad-hoc transaction.

*Important*:

Many APIs used for writing MySQL client applications (such as JDBC)
provide their own methods for starting transactions that can (and
sometimes should) be used instead of sending a *Note `START
TRANSACTION': commit. statement from the client. See *Note
connectors-apis::, or the documentation for your API, for more
information.

The *Note `BEGIN': commit.  statement differs from the use of the
`BEGIN' keyword that starts a `BEGIN ... END' compound statement. The
latter does not begin a transaction. See *Note begin-end::.

You can also begin a transaction like this:

     START TRANSACTION WITH CONSISTENT SNAPSHOT;

The `WITH CONSISTENT SNAPSHOT' clause starts a consistent read for
storage engines that are capable of it:

   * For `InnoDB', the effect is the same as issuing a *Note `START
     TRANSACTION': commit. followed by a *Note `SELECT': select. from
     any `InnoDB' table. See *Note innodb-consistent-read::. The `WITH
     CONSISTENT SNAPSHOT' clause does not change the current
     transaction isolation level, so it provides a consistent snapshot
     only if the current isolation level is one that allows consistent
     read (`REPEATABLE READ' or `SERIALIZABLE').

   * For Falcon, the current isolation level does not matter.  `START
     TRANSACTION WITH CONSISTENT SNAPSHOT'a always starts a transaction
     in `REPEATABLE READ' isolation level, as if
     `falcon_consistent_read' is enabled.

Beginning a transaction causes any pending transaction to be committed.
See *Note implicit-commit::, for more information.

Beginning a transaction also causes table locks acquired with *Note
`LOCK TABLES': lock-tables. to be released, as though you had executed
*Note `UNLOCK TABLES': lock-tables. Beginning a transaction does not
release a global read lock acquired with *Note `FLUSH TABLES WITH READ
LOCK': flush.

For best results, transactions should be performed using only tables
managed by a single transaction-safe storage engine.  Otherwise, the
following problems can occur:

   * If you use tables from more than one transaction-safe storage
     engine (such as `InnoDB' and `Falcon'), and the transaction
     isolation level is not `SERIALIZABLE', it is possible that when
     one transaction commits, another ongoing transaction that uses the
     same tables will see only some of the changes made by the first
     transaction. That is, the atomicity of transactions is not
     guaranteed with mixed engines and inconsistencies can result. (If
     mixed-engine transactions are infrequent, you can use *Note `SET
     TRANSACTION ISOLATION LEVEL': set-transaction. to set the isolation
     level to `SERIALIZABLE' on a per-transaction basis as necessary.)

   * If you use tables that are not transaction-safe within a
     transaction, changes to those tables are stored at once,
     regardless of the status of autocommit mode.

   * If you issue a *Note `ROLLBACK': commit.  statement after updating
     a non-transactional table within a transaction, an
     `ER_WARNING_NOT_COMPLETE_ROLLBACK' warning occurs. Changes to
     transaction-safe tables are rolled back, but not changes to
     non-transaction-safe tables.

Each transaction is stored in the binary log in one chunk, upon *Note
`COMMIT': commit. Transactions that are rolled back are not logged.
(*Exception*: Modifications to non-transactional tables cannot be
rolled back. If a transaction that is rolled back includes
modifications to non-transactional tables, the entire transaction is
logged with a *Note `ROLLBACK': commit.  statement at the end to ensure
that modifications to the non-transactional tables are replicated.) See
*Note binary-log::.

You can change the isolation level for transactions with *Note `SET
TRANSACTION ISOLATION LEVEL': set-transaction. See *Note
set-transaction::.

Rolling back can be a slow operation that may occur implicitly without
the user having explicitly asked for it (for example, when an error
occurs). Because of this, *Note `SHOW PROCESSLIST': show-processlist.
displays `Rolling back' in the `State' column for the session, not only
for explicit rollbacks performed with the *Note `ROLLBACK': commit.
statement but also for implicit rollbacks.


File: manual.info,  Node: cannot-roll-back,  Next: implicit-commit,  Prev: commit,  Up: sql-syntax-transactions

12.4.2 Statements That Cannot Be Rolled Back
--------------------------------------------

Some statements cannot be rolled back. In general, these include data
definition language (DDL) statements, such as those that create or drop
databases, those that create, drop, or alter tables or stored routines.

You should design your transactions not to include such statements. If
you issue a statement early in a transaction that cannot be rolled
back, and then another statement later fails, the full effect of the
transaction cannot be rolled back in such cases by issuing a *Note
`ROLLBACK': commit.  statement.


File: manual.info,  Node: implicit-commit,  Next: savepoint,  Prev: cannot-roll-back,  Up: sql-syntax-transactions

12.4.3 Statements That Cause an Implicit Commit
-----------------------------------------------

The statements listed in this section (and any synonyms for them)
implicitly end a transaction, as if you had done a *Note `COMMIT':
commit. before executing the statement. As of MySQL 6.0.8, most of
these statements also cause an implicit commit after executing; for
additional details, see the end of this section.

   * *Data definition language (DDL) statements that define or modify
     database objects.* `ALTER DATABASE ... UPGRADE DATA DIRECTORY
     NAME', *Note `ALTER EVENT': alter-event, *Note `ALTER PROCEDURE':
     alter-procedure, *Note `ALTER TABLE': alter-table, *Note `ALTER
     VIEW': alter-view, *Note `CREATE DATABASE': create-database, *Note
     `CREATE EVENT': create-event, *Note `CREATE INDEX': create-index,
     *Note `CREATE PROCEDURE': create-procedure, *Note `CREATE TABLE':
     create-table, *Note `CREATE TRIGGER': create-trigger, *Note
     `CREATE VIEW': create-view, *Note `DROP DATABASE': drop-database,
     *Note `DROP EVENT': drop-event, *Note `DROP INDEX': drop-index,
     *Note `DROP PROCEDURE': drop-procedure, *Note `DROP TABLE':
     drop-table, *Note `DROP TRIGGER': drop-trigger, *Note `DROP VIEW':
     drop-view, *Note `RENAME TABLE': rename-table, *Note `TRUNCATE
     TABLE': truncate.

     *Note `ALTER FUNCTION': alter-function, *Note `CREATE FUNCTION':
     create-function. and *Note `DROP FUNCTION': drop-function. also
     cause an implicit commit when used with stored functions, but not
     with UDFs. (*Note `ALTER FUNCTION': alter-function. can only be
     used with stored functions.)

     *Note `ALTER TABLE': alter-table, *Note `CREATE TABLE':
     create-table, and *Note `DROP TABLE': drop-table. do not commit a
     transaction if the `TEMPORARY' keyword is used. (This does not
     apply to other operations on temporary tables such as *Note
     `CREATE INDEX': create-index, which do cause a commit.) However,
     although no implicit commit occurs, neither can the statement be
     rolled back. Therefore, use of such statements will violate
     transaction atomicity: For example, if you use *Note `CREATE
     TEMPORARY TABLE': create-table. and then roll back the
     transaction, the table remains in existence.

     The *Note `CREATE TABLE': create-table. statement in `InnoDB' is
     processed as a single transaction. This means that a *Note
     `ROLLBACK': commit.  from the user does not undo *Note `CREATE
     TABLE': create-table. statements the user made during that
     transaction.

     `CREATE TABLE ... SELECT' causes an implicit commit before and
     after the statement is executed when you are creating
     non-temporary tables. (No commit occurs for `CREATE TEMPORARY
     TABLE ... SELECT'.) This is to prevent an issue during replication
     where the table could be created on the master after a rollback,
     but fail to be recorded in the binary log, and therefore not
     replicated to the slave. For more information, see Bug#22865
     (http://bugs.mysql.com/22865).

   * *Statements that implicitly use or modify tables in the `mysql'
     database.* *Note `CREATE USER': create-user, *Note `DROP USER':
     drop-user, *Note `RENAME USER': rename-user.

     Beginning with MySQL 6.0.3, *Note `GRANT': grant. and *Note
     `REVOKE': revoke. statements cause an implicit commit. Beginning
     with MySQL 6.0.4, *Note `SET PASSWORD': set-password. statements
     cause an implicit commit.

   * *Transaction-control and locking statements.* *Note `BEGIN':
     commit, *Note `LOCK TABLES': lock-tables, `SET autocommit = 1' (if
     the value is not already 1), *Note `START TRANSACTION': commit,
     *Note `UNLOCK TABLES': lock-tables.

     *Note `UNLOCK TABLES': lock-tables. commits a transaction only if
     any tables currently have been locked with *Note `LOCK TABLES':
     lock-tables. to acquire non-transactional table locks. A commit
     does not occur for *Note `UNLOCK TABLES': lock-tables. following
     *Note `FLUSH TABLES WITH READ LOCK': flush. because the latter
     statement does not acquire table-level locks.

     Transactions cannot be nested. This is a consequence of the
     implicit commit performed for any current transaction when you
     issue a *Note `START TRANSACTION': commit. statement or one of its
     synonyms.

     Statements that cause an implicit commit cannot be used in an XA
     transaction while the transaction is in an `ACTIVE' state.

     The *Note `BEGIN': commit.  statement differs from the use of the
     `BEGIN' keyword that starts a `BEGIN ... END' compound statement.
     The latter does not cause an implicit commit. See *Note
     begin-end::.

   * *Data loading statements.* *Note `LOAD DATA INFILE': load-data.
     (for `NDB' only; see Bug#11151 (http://bugs.mysql.com/11151)).

   * *Administrative statements.* *Note `ANALYZE TABLE': analyze-table,
     *Note `BACKUP DATABASE': backup-database, *Note `CACHE INDEX':
     cache-index, *Note `CHECK TABLE': check-table, *Note `LOAD INDEX
     INTO CACHE': load-index, *Note `OPTIMIZE TABLE': optimize-table,
     *Note `REPAIR TABLE': repair-table, *Note `RESTORE': restore.

As of MySQL 6.0.8, most statements that previously caused an implicit
commit before executing also do so after executing. The intent is to
handle each such statement in its own special transaction because it
cannot be rolled back anyway. The following list provides additional
details pertaining to this change:

   * The *Note `CREATE TABLE': create-table. variants (*Note `CREATE
     TABLE': create-table. for `InnoDB' tables and `CREATE TABLE ...
     SELECT') that previously were special cases no longer are so
     because *Note `CREATE TABLE': create-table.  uniformly causes an
     implicit commit before and after executing.

   * The *Note `FLUSH': flush. statement causes an implicit commit.

   * Transaction-control and locking statements behave as before.


File: manual.info,  Node: savepoint,  Next: lock-tables,  Prev: implicit-commit,  Up: sql-syntax-transactions

12.4.4 `SAVEPOINT' and `ROLLBACK TO SAVEPOINT' Syntax
-----------------------------------------------------

     SAVEPOINT IDENTIFIER
     ROLLBACK [WORK] TO [SAVEPOINT] IDENTIFIER
     RELEASE SAVEPOINT IDENTIFIER

`InnoDB' and Falcon support the SQL statements *Note `SAVEPOINT':
savepoint, *Note `ROLLBACK TO SAVEPOINT': commit, *Note `RELEASE
SAVEPOINT': commit. and the optional `WORK' keyword for *Note
`ROLLBACK': commit.

The *Note `SAVEPOINT': savepoint. statement sets a named transaction
savepoint with a name of IDENTIFIER. If the current transaction has a
savepoint with the same name, the old savepoint is deleted and a new
one is set.

The *Note `ROLLBACK TO SAVEPOINT': commit. statement rolls back a
transaction to the named savepoint without terminating the transaction.
Modifications that the current transaction made to rows after the
savepoint was set are undone in the rollback, but `InnoDB' does _not_
release the row locks that were stored in memory after the savepoint.
(For a new inserted row, the lock information is carried by the
transaction ID stored in the row; the lock is not separately stored in
memory. In this case, the row lock is released in the undo.) Savepoints
that were set at a later time than the named savepoint are deleted.

If the *Note `ROLLBACK TO SAVEPOINT': commit. statement returns the
following error, it means that no savepoint with the specified name
exists:

     ERROR 1181: Got error 153 during ROLLBACK

The *Note `RELEASE SAVEPOINT': commit. statement removes the named
savepoint from the set of savepoints of the current transaction. No
commit or rollback occurs. It is an error if the savepoint does not
exist.

All savepoints of the current transaction are deleted if you execute a
*Note `COMMIT': commit, or a *Note `ROLLBACK': commit. that does not
name a savepoint.

A new savepoint level is created when a stored function is invoked or a
trigger is activated. The savepoints on previous levels become
unavailable and thus do not conflict with savepoints on the new level.
When the function or trigger terminates, any savepoints it created are
released and the previous savepoint level is restored.


File: manual.info,  Node: lock-tables,  Next: set-transaction,  Prev: savepoint,  Up: sql-syntax-transactions

12.4.5 `LOCK TABLES' and `UNLOCK TABLES' Syntax
-----------------------------------------------

* Menu:

* lock-tables-and-transactions::  Interaction of Table Locking and Transactions
* lock-tables-and-triggers::     `LOCK TABLES' and Triggers
* lock-tables-notes::            Other Table-Locking Notes

     LOCK TABLES
         TBL_NAME [[AS] ALIAS] LOCK_TYPE
         [, TBL_NAME [[AS] ALIAS] LOCK_TYPE] ...

     LOCK_TYPE:
         READ [LOCAL]
       | [LOW_PRIORITY] WRITE
       | IN SHARE MODE [NOWAIT]
       | IN EXCLUSIVE MODE [NOWAIT]

     UNLOCK TABLES

MySQL enables client sessions to acquire table locks explicitly for the
purpose of cooperating with other sessions for access to tables, or to
prevent other sessions from modifying tables during periods when a
session requires exclusive access to them. A session can acquire or
release locks only for itself. One session cannot acquire locks for
another session or release locks held by another session.

MySQL 6.0 supports non-transactional and transactional locks. These are
intended for use in non-transactional or transactional context,
respectively.  Non-transactional locks may be used to emulate
transactions or to get more speed when updating tables. This is
explained in more detail later in this section.

*Note `LOCK TABLES': lock-tables. explicitly acquires non-transactional
or transactional table locks for the current client session. Table
locks can be acquired for base tables or views. You must have the `LOCK
TABLES' privilege, and the `SELECT' privilege for each object to be
locked.

For view locking, *Note `LOCK TABLES': lock-tables. adds all base
tables used in the view to the set of tables to be locked and locks
them automatically. If you lock a table explicitly with *Note `LOCK
TABLES': lock-tables, any tables used in triggers are also locked
implicitly, as described in *Note lock-tables-and-triggers::.

*Note `UNLOCK TABLES': lock-tables. explicitly releases
non-transactional table locks held by the current session.
Transactional table locks are released by ending the current
transaction.

Another use for *Note `UNLOCK TABLES': lock-tables. is to release the
global read lock acquired with the *Note `FLUSH TABLES WITH READ LOCK':
flush. statement, which enables you to lock all tables in all
databases. See *Note flush::. (This is a very convenient way to get
backups if you have a file system such as Veritas that can take
snapshots in time.)

A table lock protects only against inappropriate reads or writes by
other sessions. The session holding the lock can perform table-level
operations such as *Note `DROP TABLE': drop-table. Truncate operations
are not transaction-safe, so an error occurs if the session attempts
one during an active transaction or while holding a table lock.

As of MySQL 6.0.3, *Note `DROP TABLE': drop-table. is allowed only if
you have acquired a `WRITE' lock with *Note `LOCK TABLES': lock-tables,
or if you hold no locks, or if the table is a `TEMPORARY' table.
Previously, if other tables were locked, you could drop a table while
holding a read lock or no lock for it, which could lead to deadlocks
between sessions. The current stricter behavior means that some usage
scenarios will fail when previously they did not.

The following discussion applies only to non-`TEMPORARY' tables. *Note
`LOCK TABLES': lock-tables. is allowed (but ignored) for a `TEMPORARY'
table. The table can be accessed freely by the session within which it
was created, regardless of what other locking may be in effect. No lock
is necessary because no other session can see the table.

*Rules for Lock Acquisition*

To acquire non-transactional or transactional table locks within the
current session, use the *Note `LOCK TABLES': lock-tables. statement.

*Rules for acquisition of non-transactional locks.* MySQL supports
non-transactional read and write table locks. These can be acquired in
non-transactional contexts (that is, when autocommit is enabled).

`READ [LOCAL]' lock:

   * The session that holds the lock can read the table (but not write
     it).

   * Multiple sessions can acquire a `READ' lock for the table at the
     same time.

   * Other sessions can read the table without explicitly acquiring a
     `READ' lock.

   * The `LOCAL' modifier enables concurrent inserts by other sessions
     to proceed while the lock is held.  (See *Note
     concurrent-inserts::.)

`[LOW_PRIORITY] WRITE' lock:

   * The session that holds the lock can read and write the table.

   * Only the session that holds the lock can access the table. No
     other session can access it until the lock is released.

   * Lock requests for the table by other sessions block while the
     `WRITE' lock is held.

   * The `LOW_PRIORITY' modifier affects lock scheduling if the `WRITE'
     lock request must wait, as described later.

A session that requires non-transactional locks must acquire all the
locks that it needs in a single *Note `LOCK TABLES': lock-tables.
statement. While the locks thus obtained are held, the session can
access only the locked tables. For example, in the following sequence
of statements, an error occurs for the attempt to access `t2' because
it was not locked in the *Note `LOCK TABLES': lock-tables. statement:

     mysql> LOCK TABLES t1 READ;
     mysql> SELECT COUNT(*) FROM t1;
     +----------+
     | COUNT(*) |
     +----------+
     |        3 |
     +----------+
     mysql> SELECT COUNT(*) FROM t2;
     ERROR 1100 (HY000): Table 't2' was not locked with LOCK TABLES

Tables in the `INFORMATION_SCHEMA' database are an exception. They can
be accessed without being locked explicitly even while a session holds
table locks obtained with *Note `LOCK TABLES': lock-tables.

A session cannot hold non-transactional locks and use transactions at
the same time. Acquisition of a non-transactional lock implicitly
commits any active transaction for the current session, and beginning a
transaction implicitly releases all locks held by the session.
(Additional information about the interaction between table locking and
transactions is given in *Note lock-tables-and-transactions::.)

The difference between `READ' and `READ LOCAL' is that `READ LOCAL'
allows non-conflicting *Note `INSERT': insert. statements (concurrent
inserts) to execute while the lock is held. However, `READ LOCAL'
cannot be used if you are going to manipulate the database using
processes external to the server while you hold the lock. For `InnoDB'
tables, `READ LOCAL' is the same as `READ'.

`WRITE' locks normally have higher priority than `READ' locks to ensure
that updates are processed as soon as possible. This means that if one
session obtains a `READ' lock and then another session requests a
`WRITE' lock, subsequent `READ' lock requests wait until the session
that requested the `WRITE' lock has obtained the lock and released it.
A request for a `LOW_PRIORITY WRITE' lock, by contrast, allows
subsequent `READ' lock requests by other sessions to be satisfied first
if they occur while the `LOW_PRIORITY WRITE' request is waiting. You
should use `LOW_PRIORITY WRITE' locks only if you are sure that
eventually there will be a time when no sessions have a `READ' lock.
For `InnoDB' tables in transactional mode (autocommit = 0), a waiting
`LOW_PRIORITY WRITE' lock acts like a regular `WRITE' lock and causes
subsequent `READ' lock requests to wait.

For non-transactional locks, *Note `LOCK TABLES': lock-tables. acquires
locks as follows:

  1. Sort all tables to be locked in an internally defined order.  From
     the user standpoint, this order is undefined.

  2. If a table is to be locked with a read and a write lock, put the
     write lock request before the read lock request.

  3. Lock one table at a time until the session gets all locks.

This policy ensures that table locking is deadlock free. There are,
however, other things you need to be aware of about this policy: If you
are using a `LOW_PRIORITY WRITE' lock for a table, it means only that
MySQL waits for this particular lock until there are no other sessions
that want a `READ' lock. When the session has gotten the `WRITE' lock
and is waiting to get the lock for the next table in the lock table
list, all other sessions wait for the `WRITE' lock to be released. If
this becomes a serious problem with your application, you should
consider converting some of your tables to transaction-safe tables.

*Rules for acquisition of transactional locks.* As of MySQL 6.0.3,
MySQL supports transactional shared and exclusive table locks that do
not commit transactions automatically. These locks apply only for
transactional storage engines that support them and only during a
transaction (that is, when autocommit is disabled).

Currently, only `InnoDB' supports transactional locks. For other
transactional storage engines or for non-transactional storage engines,
requests for transactional locks are converted to requests for
non-transactional locks, as described later.

`IN SHARE MODE [NOWAIT]' lock:

   * The session that holds the lock can read the table, and can also
     write the table under some circumstances.

   * Multiple sessions can acquire an `IN SHARE MODE' lock for the
     table at the same time.

   * Other sessions can read the table without explicitly acquiring an
     `IN SHARE MODE' lock.

`IN EXCLUSIVE MODE [NOWAIT]' lock:

   * The session that holds the lock can read and write the table.

   * Only the session that holds the lock can access the table. No
     other session can access it until the lock is released.

   * Lock requests for the table by other sessions block while the `IN
     EXCLUSIVE MODE' lock is held.

By default, *Note `LOCK TABLES': lock-tables. waits if all requested
locks cannot be acquired immediately (for example, if the requests
cannot be granted due to locks held by other sessions). For
transactional locks, the `NOWAIT' modifier can be given. The intent of
this modifier is that the lock request will fail with an error if the
lock cannot be acquired immediately, but `NOWAIT' is not currently
implemented by any storage engine.

A session that requires transactional locks need not acquire them all
in a single *Note `LOCK TABLES': lock-tables.  statement. A session can
acquire transactional locks sequentially with multiple *Note `LOCK
TABLES': lock-tables.  statements, each one adding new locks to the
current set of locks.  It is even possible to acquire additional
transactional locks on a table for which the session already holds
transactional locks.

A session that holds transactional locks can access non-locked tables
while the locks are held.

Transactional locks are not specific to reading or writing. Both
operations are allowed to the holder of the lock, whether it is shared
or exclusive, with some restrictions:

   * The holder of an `IN EXCLUSIVE MODE' lock has exclusive access to
     read and write the table and no other session can lock the table.

   * The holder of an `IN SHARE MODE' lock has shared access to read
     the table. The lock holder can also write the table, as long as no
     other session also has a shared lock for the table. If a session
     that holds a shared lock has written to the table, no other
     session can acquire a lock for the table.

Transactional locks do not apply if a session is not in transactional
context; that is, when autocommit mode is enabled because the session
has not used *Note `START TRANSACTION': commit. or `SET autocommit =
0'. In this case, the lock is released as soon as the *Note `LOCK
TABLES': lock-tables. statement ends, which makes the statement almost
a non-operation. The only difference is that the request blocks if it
must wait for an existing lock to be released, but then the new lock is
immediately released.

For *Note `LOCK TABLES': lock-tables. statements that involve a mix of
non-transactional and transactional locks, requests for transactional
locks are converted to requests for non-transactional locks. This
occurs because a session can hold multiple locks at a time, but cannot
hold a mix of non-transactional and transactional locks:

   * It is permissible to hold multiple `READ' or `WRITE' locks at the
     same time.

   * It is permissible to hold multiple `IN SHARE MODE' or `IN
     EXCLUSIVE MODE' locks at the same time.

   * It is not possible to hold a `READ' or `WRITE' lock at the same
     time as an `IN SHARE MODE' or `IN EXCLUSIVE MODE' lock.

For example, these operations are allowed because they request only
non-transactional locks, or only transactional locks:

     LOCK TABLES t1 READ, t2 WRITE, t3 READ;
     LOCK TABLES t4 IN SHARE MODE, t5 IN EXCLUSIVE MODE, t6 IN SHARE MODE;

But these operations cannot be processed as requested because they
attempt to acquire a mix of non-transactional and transactional locks:

     LOCK TABLES t1 READ, t2 IN SHARE MODE;
     LOCK TABLES t3 WRITE, t4 IN EXCLUSIVE MODE;

For the latter statements, the requests for transactional locks are
converted to requests for non-transactional locks. Lock conversions may
succeed or fail, as described later.

You cannot refer to a locked table multiple times in a single query
using the same name. Use aliases instead, and obtain a separate lock
for the table and each alias:

     mysql> LOCK TABLE t WRITE, t AS t1 READ;
     mysql> INSERT INTO t SELECT * FROM t;
     ERROR 1100: Table 't' was not locked with LOCK TABLES
     mysql> INSERT INTO t SELECT * FROM t AS t1;

The error occurs for the first *Note `INSERT': insert. because there
are two references to the same name for a locked table. The second
*Note `INSERT': insert. succeeds because the references to the table
use different names.

If your statements refer to a table by means of an alias, you must lock
the table using that same alias. It does not work to lock the table
without specifying the alias:

     mysql> LOCK TABLE t READ;
     mysql> SELECT * FROM t AS myalias;
     ERROR 1100: Table 'myalias' was not locked with LOCK TABLES

Conversely, if you lock a table using an alias, you must refer to it in
your statements using that alias:

     mysql> LOCK TABLE t AS myalias READ;
     mysql> SELECT * FROM t;
     ERROR 1100: Table 't' was not locked with LOCK TABLES
     mysql> SELECT * FROM t AS myalias;

*Rules for Lock Release*

When the table locks held by a session are released, they are all
released at the same time. A session can release its locks explicitly,
or locks may be released implicitly under certain conditions.

Rules for lock release when a session holds non-transactional locks:

   * A session can release its locks explicitly with *Note `UNLOCK
     TABLES': lock-tables.

   * If a session issues a *Note `LOCK TABLES': lock-tables. statement
     to acquire a lock while already holding non-transactional locks,
     its existing locks are released implicitly before the new locks
     are granted.

   * If a session begins a transaction, an implicit *Note `UNLOCK
     TABLES': lock-tables. is performed, which causes existing locks to
     be released.

   * If the connection for a client session terminates, the server
     releases the session's locks.

Rules for lock release when a session holds transactional locks:

   * *Note `UNLOCK TABLES': lock-tables. does _not_ release
     transactional locks.

   * Ending a transaction explicitly, by either *Note `COMMIT': commit.
     or *Note `ROLLBACK': commit, releases existing locks.

   * Beginning a transaction implicitly commits the current
     transaction, which releases existing locks.

   * If the session issues a *Note `LOCK TABLES': lock-tables. request
     for a non-transactional lock, that implicitly commits the current
     transaction, which releases existing locks.

   * Any other statement that causes an implicit commit releases the
     existing locks. For a list, see *Note implicit-commit::.

   * If the connection for a client session terminates, the server
     implicitly rolls back the current transaction and releases the
     session's locks.

If a client connection drops, the server releases table locks held by
the client. If the client reconnects, the locks will no longer be in
effect. In addition, if the client had an active transaction, the
server rolls back the transaction upon disconnect, and if reconnect
occurs, the new session begins with autocommit enabled. For this
reason, clients may wish to disable auto-reconnect. With auto-reconnect
in effect, the client is not notified if reconnect occurs but any table
locks or current transaction will have been lost. With auto-reconnect
disabled, if the connection drops, an error occurs for the next
statement issued. The client can detect the error and take appropriate
action such as reacquiring the locks or redoing the transaction.  See
*Note auto-reconnect::.

*Note*:

If you use *Note `ALTER TABLE': alter-table. on a locked table, it may
become unlocked. See *Note alter-table-problems::.

*Rules for Transactional Lock Conversion*

Under some circumstances, a request for a transactional lock cannot be
granted:

   * A session cannot use *Note `LOCK TABLES': lock-tables. to
     simultaneously acquire transactional and non-transactional locks.

   * A session cannot acquire transactional locks while currently
     holding non-transactional locks.

   * A session cannot acquire transactional locks for storage engines
     that do not support them:

        * The table to be locked is non-transactional (for example,
          `MyISAM').

        * The table to be locked is transactional but the storage
          engine does not support transactional locks. (Currently, only
          `InnoDB' supports transactional locks.)

When a transactional lock cannot be granted for the preceding reasons,
the request is converted to a request for a non-transactional lock. The
conversion is handled as follows:

   * If strict SQL mode is enabled, lock conversion is prohibited and
     an error occurs.

          mysql> SET sql_mode = 'STRICT_TRANS_TABLES,STRICT_ALL_TABLES';
          Query OK, 0 rows affected (0.00 sec)

          mysql> LOCK TABLES t1 READ, t2 IN SHARE MODE;
          ERROR 1615 (HY000): Cannot convert to non-transactional lock in
          strict mode on 't2'

   * Otherwise, conversion occurs and a warning is generated.

          mysql> SET sql_mode = '';
          Query OK, 0 rows affected (0.00 sec)

          mysql> LOCK TABLES t1 READ, t2 IN SHARE MODE;
          Query OK, 0 rows affected, 1 warning (0.00 sec)

          mysql> SHOW WARNINGS;
          +---------+------+---------------------------------------------+
          | Level   | Code | Message                                     |
          +---------+------+---------------------------------------------+
          | Warning | 1614 | Converted to non-transactional lock on 't2' |
          +---------+------+---------------------------------------------+
          1 row in set (0.00 sec)

   * When conversion occurs, `IN SHARE MODE' is converted to `READ' and
     `IN EXCLUSIVE MODE' is converted to `WRITE'.

The following notes describe what happens when a session already holds
one type of lock and then requests another lock:

   * Session holds a non-transactional lock, and then requests a
     non-transactional lock:

       1. An implicit *Note `UNLOCK TABLES': lock-tables. occurs, which
          releases the existing non-transactional lock.

       2. The new non-transactional lock is granted.

   * Session holds a non-transactional lock, and then requests a
     transactional lock:

       1. The request is converted to a request for a non-transactional
          lock.

       2. An implicit *Note `UNLOCK TABLES': lock-tables. occurs, which
          releases the existing non-transactional lock.

       3. The new non-transactional lock is granted.

   * Session holds a transactional lock, and then requests a
     transactional lock

     The new transactional lock is granted without releasing the
     existing transactional lock.

   * Session holds a transactional lock, and then requests a
     non-transactional lock

       1. An implicit commit occurs, which releases the existing
          transactional lock.

       2. The new non-transactional lock is granted.

     Thus, the following sequence results in insertion of a row, even
     though there is no explicit commit:

          DROP TABLE IF EXISTS t;
          CREATE TABLE t (i INT) ENGINE = InnoDB;
          START TRANSACTION;
          LOCK TABLE t IN EXCLUSIVE MODE;
          INSERT INTO t VALUES(1);
          LOCK TABLE t READ;
          SELECT * FROM t;


File: manual.info,  Node: lock-tables-and-transactions,  Next: lock-tables-and-triggers,  Prev: lock-tables,  Up: lock-tables

12.4.5.1 Interaction of Table Locking and Transactions
......................................................

*Note `LOCK TABLES': lock-tables. and *Note `UNLOCK TABLES':
lock-tables. interact with the use of transactions as follows:

   * When used to acquire non-transactional locks, *Note `LOCK TABLES':
     lock-tables. is not transaction-safe and implicitly commits any
     active transaction before attempting to lock the tables.

   * *Note `UNLOCK TABLES': lock-tables. implicitly commits any active
     transaction, but only if *Note `LOCK TABLES': lock-tables. has
     been used to acquire non-transactional table locks. For example,
     in the following set of statements, *Note `UNLOCK TABLES':
     lock-tables. releases the global read lock but does not commit the
     transaction because no non-transactional table locks are in effect:

          FLUSH TABLES WITH READ LOCK;
          START TRANSACTION;
          SELECT ... ;
          UNLOCK TABLES;

   * Beginning a transaction (for example, with *Note `START
     TRANSACTION': commit.) implicitly commits any current transaction
     and releases existing locks.

   * Other statements that implicitly cause transactions to be
     committed do not release existing locks. For a list of such
     statements, see *Note implicit-commit::.

   * The correct way to use *Note `LOCK TABLES': lock-tables. and *Note
     `UNLOCK TABLES': lock-tables. with non-tranactional locks and
     transactional tables, such as `InnoDB' tables, is to begin a
     transaction with `SET autocommit = 0' (not *Note `START
     TRANSACTION': commit.) followed by *Note `LOCK TABLES':
     lock-tables, and to not call *Note `UNLOCK TABLES': lock-tables.
     until you commit the transaction explicitly. For example, if you
     need to write to table `t1' and read from table `t2', you can do
     this:

          SET autocommit=0;
          LOCK TABLES t1 WRITE, t2 READ, ...;
          ... DO SOMETHING WITH TABLES T1 AND T2 HERE ...
          COMMIT;
          UNLOCK TABLES;

     When you call *Note `LOCK TABLES': lock-tables, `InnoDB'
     internally takes its own table lock, and MySQL takes its own table
     lock.  `InnoDB' releases its internal table lock at the next
     commit, but for MySQL to release its table lock, you have to call
     *Note `UNLOCK TABLES': lock-tables. You should not have
     `autocommit = 1', because then `InnoDB' releases its internal table
     lock immediately after the call of *Note `LOCK TABLES':
     lock-tables, and deadlocks can very easily happen.  `InnoDB' does
     not acquire the internal table lock at all if `autocommit = 1', to
     help old applications avoid unnecessary deadlocks.

   * *Note `ROLLBACK': commit.  does not release non-transactional
     table locks.

   * *Note `FLUSH TABLES WITH READ LOCK': flush. acquires a global read
     lock and not table locks, so it is not subject to the same
     behavior as *Note `LOCK TABLES': lock-tables. and *Note `UNLOCK
     TABLES': lock-tables. with respect to table locking and implicit
     commits. See *Note flush::.


File: manual.info,  Node: lock-tables-and-triggers,  Next: lock-tables-notes,  Prev: lock-tables-and-transactions,  Up: lock-tables

12.4.5.2 `LOCK TABLES' and Triggers
...................................

If you lock a table explicitly with *Note `LOCK TABLES': lock-tables,
any tables used in triggers are also locked implicitly:

   * The locks are taken as the same time as those acquired explicitly
     with the *Note `LOCK TABLES': lock-tables. statement.

   * The lock on a table used in a trigger depends on whether the table
     is used only for reading. If so, a read lock suffices.  Otherwise,
     a write lock is used.

   * If a table is locked explicitly for reading with *Note `LOCK
     TABLES': lock-tables, but needs to be locked for writing because
     it might be modified within a trigger, a write lock is taken
     rather than a read lock.  (That is, an implicit write lock needed
     due to the table's appearance within a trigger causes an explicit
     read lock request for the table to be converted to a write lock
     request.)

Suppose that you lock two tables, `t1' and `t2', using this statement:

     LOCK TABLES t1 WRITE, t2 READ;

If `t1' or `t2' have any triggers, tables used within the triggers will
also be locked.  Suppose that `t1' has a trigger defined like this:

     CREATE TRIGGER t1_a_ins AFTER INSERT ON t1 FOR EACH ROW
     BEGIN
       UPDATE t4 SET count = count+1
           WHERE id = NEW.id AND EXISTS (SELECT a FROM t3);
       INSERT INTO t2 VALUES(1, 2);
     END;

The result of the *Note `LOCK TABLES': lock-tables.  statement is that
`t1' and `t2' are locked because they appear in the statement, and `t3'
and `t4' are locked because they are used within the trigger:

   * `t1' is locked for writing per the `WRITE' lock request.

   * `t2' is locked for writing, even though the request is for a
     `READ' lock. This occurs because `t2' is inserted into within the
     trigger, so the `READ' request is converted to a `WRITE' request.

   * `t3' is locked for reading because it is only read from within the
     trigger.

   * `t4' is locked for writing because it might be updated within the
     trigger.


File: manual.info,  Node: lock-tables-notes,  Prev: lock-tables-and-triggers,  Up: lock-tables

12.4.5.3 Other Table-Locking Notes
..................................

You can safely use *Note `KILL': kill. to terminate a session that is
waiting for a table lock. See *Note kill::.

You should _not_ lock any tables that you are using with *Note `INSERT
DELAYED': insert-delayed. An *Note `INSERT DELAYED': insert-delayed. in
this case results in an error because the insert must be handled by a
separate thread, not by the session which holds the lock.

For some operations, system tables in the `mysql' database must be
accessed. For example, the *Note `HELP': help. statement requires the
contents of the server-side help tables, and `CONVERT_TZ()' might need
to read the time zone tables. The server implicitly locks the system
tables for reading as necessary so that you need not lock them
explicitly. These tables are treated as just described:

     mysql.help_category
     mysql.help_keyword
     mysql.help_relation
     mysql.help_topic
     mysql.proc
     mysql.time_zone
     mysql.time_zone_leap_second
     mysql.time_zone_name
     mysql.time_zone_transition
     mysql.time_zone_transition_type

If you want to explicitly place a `WRITE' lock on any of those tables
with a *Note `LOCK TABLES': lock-tables. statement, the table must be
the only one locked; no other table can be locked with the same
statement.

Normally, you do not need to lock tables, because all single *Note
`UPDATE': update. statements are atomic; no other session can interfere
with any other currently executing SQL statement. However, there are a
few cases when locking tables may provide an advantage:

   * If you are going to run many operations on a set of `MyISAM'
     tables, it is much faster to lock the tables you are going to use.
     Locking `MyISAM' tables speeds up inserting, updating, or deleting
     on them because MySQL does not flush the key cache for the locked
     tables until *Note `UNLOCK TABLES': lock-tables. is called.
     Normally, the key cache is flushed after each SQL statement.

     The downside to locking the tables is that no session can update a
     `READ'-locked table (including the one holding the lock) and no
     session can access a `WRITE'-locked table other than the one
     holding the lock.

   * If you are using tables for a non-transactional storage engine,
     you must use *Note `LOCK TABLES': lock-tables. if you want to
     ensure that no other session modifies the tables between a *Note
     `SELECT': select. and an *Note `UPDATE': update. The example shown
     here requires *Note `LOCK TABLES': lock-tables. to execute safely:

          LOCK TABLES trans READ, customer WRITE;
          SELECT SUM(value) FROM trans WHERE customer_id=SOME_ID;
          UPDATE customer
            SET total_value=SUM_FROM_PREVIOUS_STATEMENT
            WHERE customer_id=SOME_ID;
          UNLOCK TABLES;

     Without *Note `LOCK TABLES': lock-tables, it is possible that
     another session might insert a new row in the `trans' table
     between execution of the *Note `SELECT': select. and *Note
     `UPDATE': update. statements.

You can avoid using *Note `LOCK TABLES': lock-tables.  in many cases by
using relative updates (`UPDATE customer SET VALUE=VALUE+NEW_VALUE') or
the `LAST_INSERT_ID()' function.  See *Note ansi-diff-transactions::.

You can also avoid locking tables in some cases by using the user-level
advisory lock functions `GET_LOCK()' and `RELEASE_LOCK()'. These locks
are saved in a hash table in the server and implemented with
`pthread_mutex_lock()' and `pthread_mutex_unlock()' for high speed. See
*Note miscellaneous-functions::.

See *Note internal-locking::, for more information on locking policy.


File: manual.info,  Node: set-transaction,  Next: xa,  Prev: lock-tables,  Up: sql-syntax-transactions

12.4.6 `SET TRANSACTION' Syntax
-------------------------------

     SET [GLOBAL | SESSION] TRANSACTION ISOLATION LEVEL
       {
            READ UNCOMMITTED
          | READ COMMITTED
          | REPEATABLE READ
          | SERIALIZABLE
        }

This statement sets the transaction isolation level globally, for the
current session, or for the next transaction:

   * With the `GLOBAL' keyword, the statement sets the default
     transaction level globally for all subsequent sessions. Existing
     sessions are unaffected.

   * With the `SESSION' keyword, the statement sets the default
     transaction level for all subsequent transactions performed within
     the current session.

   * Without any `SESSION' or `GLOBAL' keyword, the statement sets the
     isolation level for the next (not started) transaction performed
     within the current session.

A change to the global default isolation level requires the `SUPER'
privilege. Any session is free to change its session isolation level
(even in the middle of a transaction), or the isolation level for its
next transaction.

To set the global default isolation level at server startup, use the
`--transaction-isolation=LEVEL' option to *Note `mysqld': mysqld. on
the command line or in an option file. Values of LEVEL for this option
use dashes rather than spaces, so the allowable values are
`READ-UNCOMMITTED', `READ-COMMITTED', `REPEATABLE-READ', or
`SERIALIZABLE'. For example, to set the default isolation level to
`REPEATABLE READ', use these lines in the `[mysqld]' section of an
option file:

     [mysqld]
     transaction-isolation = REPEATABLE-READ

To determine the global and session transaction isolation levels at
runtime, check the value of the `tx_isolation' system variable:

     SELECT @@GLOBAL.tx_isolation, @@tx_isolation;

`InnoDB' supports each of the translation isolation levels described
here using different locking strategies. The default level is
`REPEATABLE READ'. For additional information about `InnoDB'
record-level locks and how it uses them to execute various types of
statements, see *Note innodb-record-level-locks::, and *Note
innodb-locks-set::.

The following list describes how MySQL supports the different
transaction levels:

   *  `READ UNCOMMITTED'

     *Note `SELECT': select. statements are performed in a non-locking
     fashion, but a possible earlier version of a row might be used.
     Thus, using this isolation level, such reads are not consistent.
     This is also called a `dirty read.' Otherwise, this isolation
     level works like `READ COMMITTED'.

   *  `READ COMMITTED'

     A somewhat Oracle-like isolation level with respect to consistent
     (non-locking) reads: Each consistent read, even within the same
     transaction, sets and reads its own fresh snapshot. See *Note
     innodb-consistent-read::.

     For locking reads (*Note `SELECT': select. with `FOR UPDATE' or
     `LOCK IN SHARE MODE'), `InnoDB' locks only index records, not the
     gaps before them, and thus allows the free insertion of new
     records next to locked records. For *Note `UPDATE': update. and
     *Note `DELETE': delete. statements, locking depends on whether the
     statement uses a unique index with a unique search condition (such
     as `WHERE id = 100'), or a range-type search condition (such as
     `WHERE id > 100'). For a unique index with a unique search
     condition, `InnoDB' locks only the index record found, not the gap
     before it. For range-type searches, `InnoDB' locks the index range
     scanned, using gap locks or next-key (gap plus index-record) locks
     to block insertions by other sessions into the gaps covered by the
     range. This is necessary because `phantom rows' must be blocked
     for MySQL replication and recovery to work.

     *Note*:

     In MySQL 6.0, if the `READ COMMITTED' isolation level is used or
     the `innodb_locks_unsafe_for_binlog' system variable is enabled,
     there is no `InnoDB' gap locking except for foreign-key constraint
     checking and duplicate-key checking. Also, record locks for
     non-matching rows are released after MySQL has evaluated the
     `WHERE' condition.

     If you use `READ COMMITTED' or enable
     `innodb_locks_unsafe_for_binlog', you _must_ use row-based binary
     logging.

   *  `REPEATABLE READ'

     This is the default isolation level for `InnoDB'. For consistent
     reads, there is an important difference from the `READ COMMITTED'
     isolation level: All consistent reads within the same transaction
     read the snapshot established by the first read. This convention
     means that if you issue several plain (non-locking) *Note
     `SELECT': select. statements within the same transaction, these
     *Note `SELECT': select.  statements are consistent also with
     respect to each other. See *Note innodb-consistent-read::.

     For locking reads (*Note `SELECT': select. with `FOR UPDATE' or
     `LOCK IN SHARE MODE'), *Note `UPDATE': update, and *Note `DELETE':
     delete. statements, locking depends on whether the statement uses
     a unique index with a unique search condition, or a range-type
     search condition. For a unique index with a unique search
     condition, `InnoDB' locks only the index record found, not the gap
     before it. For other search conditions, `InnoDB' locks the index
     range scanned, using gap locks or next-key (gap plus index-record)
     locks to block insertions by other sessions into the gaps covered
     by the range.

   *  `SERIALIZABLE'

     This level is like `REPEATABLE READ', but `InnoDB' implicitly
     converts all plain *Note `SELECT': select.  statements to *Note
     `SELECT ... LOCK IN SHARE MODE': select. if autocommit is
     disabled. If autocommit is enabled, the *Note `SELECT': select. is
     its own transaction.  It therefore is known to be read only and
     can be serialized if performed as a consistent (non-locking) read
     and need not block for other transactions. (This means that to
     force a plain *Note `SELECT': select. to block if other
     transactions have modified the selected rows, you should disable
     autocommit.)


File: manual.info,  Node: xa,  Prev: set-transaction,  Up: sql-syntax-transactions

12.4.7 XA Transactions
----------------------

* Menu:

* xa-statements::                XA Transaction SQL Syntax
* xa-states::                    XA Transaction States

Support for XA transactions is available for the `InnoDB' storage
engine. The MySQL XA implementation is based on the X/Open CAE document
`Distributed Transaction Processing: The XA Specification'. This
document is published by The Open Group and available at
`http://www.opengroup.org/public/pubs/catalog/c193.htm'.  Limitations
of the current XA implementation are described in *Note
xa-restrictions::.

On the client side, there are no special requirements. The XA interface
to a MySQL server consists of SQL statements that begin with the `XA'
keyword. MySQL client programs must be able to send SQL statements and
to understand the semantics of the XA statement interface. They do not
need be linked against a recent client library. Older client libraries
also will work.

Currently, among the MySQL Connectors, MySQL Connector/J 5.0.0 supports
XA directly (by means of a class interface that handles the Xan SQL
statement interface for you).

XA supports distributed transactions; that is, the ability to allow
multiple separate transactional resources to participate in a global
transaction. Transactional resources often are RDBMSs but may be other
kinds of resources.

A global transaction involves several actions that are transactional in
themselves, but that all must either complete successfully as a group,
or all be rolled back as a group. In essence, this extends ACID
properties `up a level' so that multiple ACID transactions can be
executed in concert as components of a global operation that also has
ACID properties.  (However, for a distributed transaction, you must use
the `SERIALIZABLE' isolation level to achieve ACID properties. It is
enough to use `REPEATABLE READ' for a non-distributed transaction, but
not for a distributed transaction.)

Some examples of distributed transactions:

   * An application may act as an integration tool that combines a
     messaging service with an RDBMS. The application makes sure that
     transactions dealing with message sending, retrieval, and
     processing that also involve a transactional database all happen
     in a global transaction. You can think of this as `transactional
     email.'

   * An application performs actions that involve different database
     servers, such as a MySQL server and an Oracle server (or multiple
     MySQL servers), where actions that involve multiple servers must
     happen as part of a global transaction, rather than as separate
     transactions local to each server.

   * A bank keeps account information in an RDBMS and distributes and
     receives money via automated teller machines (ATMs). It is
     necessary to ensure that ATM actions are correctly reflected in
     the accounts, but this cannot be done with the RDBMS alone.  A
     global transaction manager integrates the ATM and database
     resources to ensure overall consistency of financial transactions.

Applications that use global transactions involve one or more Resource
Managers and a Transaction Manager:

   * A Resource Manager (RM) provides access to transactional
     resources. A database server is one kind of resource manager.  It
     must be possible to either commit or roll back transactions
     managed by the RM.

   * A Transaction Manager (TM) coordinates the transactions that are
     part of a global transaction. It communicates with the RMs that
     handle each of these transactions. The individual transactions
     within a global transaction are `branches' of the global
     transaction. Global transactions and their branches are identified
     by a naming scheme described later.

The MySQL implementation of XA MySQL enables a MySQL server to act as a
Resource Manager that handles XA transactions within a global
transaction. A client program that connects to the MySQL server acts as
the Transaction Manager.

To carry out a global transaction, it is necessary to know which
components are involved, and bring each component to a point when it
can be committed or rolled back. Depending on what each component
reports about its ability to succeed, they must all commit or roll back
as an atomic group. That is, either all components must commit, or all
components musts roll back. To manage a global transaction, it is
necessary to take into account that any component or the connecting
network might fail.

The process for executing a global transaction uses two-phase commit
(2PC). This takes place after the actions performed by the branches of
the global transaction have been executed.

  1. In the first phase, all branches are prepared. That is, they are
     told by the TM to get ready to commit. Typically, this means each
     RM that manages a branch records the actions for the branch in
     stable storage. The branches indicate whether they are able to do
     this, and these results are used for the second phase.

  2. In the second phase, the TM tells the RMs whether to commit or
     roll back. If all branches indicated when they were prepared that
     they will be able to commit, all branches are told to commit. If
     any branch indicated when it was prepared that it will not be able
     to commit, all branches are told to roll back.

In some cases, a global transaction might use one-phase commit (1PC).
For example, when a Transaction Manager finds that a global transaction
consists of only one transactional resource (that is, a single branch),
that resource can be told to prepare and commit at the same time.


File: manual.info,  Node: xa-statements,  Next: xa-states,  Prev: xa,  Up: xa

12.4.7.1 XA Transaction SQL Syntax
..................................

To perform XA transactions in MySQL, use the following statements:

     XA {START|BEGIN} XID [JOIN|RESUME]

     XA END XID [SUSPEND [FOR MIGRATE]]

     XA PREPARE XID

     XA COMMIT XID [ONE PHASE]

     XA ROLLBACK XID

     XA RECOVER

For *Note `XA START': xa-statements, the `JOIN' and `RESUME' clauses
are not supported.

For *Note `XA END': xa-statements. the `SUSPEND [FOR MIGRATE]' clause
is not supported.

Each XA statement begins with the `XA' keyword, and most of them
require an XID value. An XID is an XA transaction identifier. It
indicates which transaction the statement applies to. XID values are
supplied by the client, or generated by the MySQL server. An XID value
has from one to three parts:

     XID: GTRID [, BQUAL [, FORMATID ]]

GTRID is a global transaction identifier, BQUAL is a branch qualifier,
and FORMATID is a number that identifies the format used by the GTRID
and BQUAL values. As indicated by the syntax, BQUAL and FORMATID are
optional. The default BQUAL value is `''' if not given. The default
FORMATID value is 1 if not given.

GTRID and BQUAL must be string literals, each up to 64 bytes (not
characters) long.  GTRID and BQUAL can be specified in several ways.
You can use a quoted string (`'ab''), hex string (`0x6162', `X'ab''), or
bit value (`b'NNNN'').

FORMATID is an unsigned integer.

The GTRID and BQUAL values are interpreted in bytes by the MySQL
server's underlying XA support routines. However, while an SQL
statement containing an XA statement is being parsed, the server works
with some specific character set. To be safe, write GTRID and BQUAL as
hex strings.

XID values typically are generated by the Transaction Manager. Values
generated by one TM must be different from values generated by other
TMs. A given TM must be able to recognize its own XID values in a list
of values returned by the *Note `XA RECOVER': xa-statements. statement.

MySQL Enterprise

For expert advice on XA Distributed Transaction Support subscribe to
the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

`XA START XID' starts an XA transaction with the given XID value. Each
XA transaction must have a unique XID value, so the value must not
currently be used by another XA transaction. Uniqueness is assessed
using the GTRID and BQUAL values. All following XA statements for the
XA transaction must be specified using the same XID value as that given
in the *Note `XA START': xa-statements. statement. If you use any of
those statements but specify an XID value that does not correspond to
some existing XA transaction, an error occurs.

One or more XA transactions can be part of the same global transaction.
All XA transactions within a given global transaction must use the same
GTRID value in the XID value. For this reason, GTRID values must be
globally unique so that there is no ambiguity about which global
transaction a given XA transaction is part of. The BQUAL part of the
XID value must be different for each XA transaction within a global
transaction. (The requirement that BQUAL values be different is a
limitation of the current MySQL XA implementation. It is not part of
the XA specification.)

The *Note `XA RECOVER': xa-statements. statement returns information
for those XA transactions on the MySQL server that are in the
`PREPARED' state. (See *Note xa-states::.) The output includes a row
for each such XA transaction on the server, regardless of which client
started it.

*Note `XA RECOVER': xa-statements. output rows look like this (for an
example XID value consisting of the parts `'abc'', `'def'', and `7'):

     mysql> XA RECOVER;
     +----------+--------------+--------------+--------+
     | formatID | gtrid_length | bqual_length | data   |
     +----------+--------------+--------------+--------+
     |        7 |            3 |            3 | abcdef |
     +----------+--------------+--------------+--------+

The output columns have the following meanings:

   * `formatID' is the FORMATID part of the transaction XID

   * `gtrid_length' is the length in bytes of the GTRID part of the XID

   * `bqual_length' is the length in bytes of the BQUAL part of the XID

   * `data' is the concatenation of the GTRID and BQUAL parts of the XID


File: manual.info,  Node: xa-states,  Prev: xa-statements,  Up: xa

12.4.7.2 XA Transaction States
..............................

An XA transaction progresses through the following states:

  1. Use *Note `XA START': xa-statements. to start an XA transaction
     and put it in the `ACTIVE' state.

  2. For an `ACTIVE' XA transaction, issue the SQL statements that make
     up the transaction, and then issue an *Note `XA END':
     xa-statements. statement.  *Note `XA END': xa-statements. puts the
     transaction in the `IDLE' state.

  3. For an `IDLE' XA transaction, you can issue either an *Note `XA
     PREPARE': xa-statements. statement or an `XA COMMIT ... ONE PHASE'
     statement:

        * *Note `XA PREPARE': xa-statements. puts the transaction in the
          `PREPARED' state. An *Note `XA RECOVER': xa-statements.
          statement at this point will include the transaction's XID
          value in its output, because *Note `XA RECOVER':
          xa-statements. lists all XA transactions that are in the
          `PREPARED' state.

        * `XA COMMIT ... ONE PHASE' prepares and commits the
          transaction. The XID value will not be listed by *Note `XA
          RECOVER': xa-statements. because the transaction terminates.

  4. For a `PREPARED' XA transaction, you can issue an *Note `XA
     COMMIT': xa-statements. statement to commit and terminate the
     transaction, or *Note `XA ROLLBACK': xa-statements. to roll back
     and terminate the transaction.

Here is a simple XA transaction that inserts a row into a table as part
of a global transaction:

     mysql> XA START 'xatest';
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO mytable (i) VALUES(10);
     Query OK, 1 row affected (0.04 sec)

     mysql> XA END 'xatest';
     Query OK, 0 rows affected (0.00 sec)

     mysql> XA PREPARE 'xatest';
     Query OK, 0 rows affected (0.00 sec)

     mysql> XA COMMIT 'xatest';
     Query OK, 0 rows affected (0.00 sec)

Within the context of a given client connection, XA transactions and
local (non-XA) transactions are mutually exclusive. For example, if
*Note `XA START': xa-statements. has been issued to begin an XA
transaction, a local transaction cannot be started until the XA
transaction has been committed or rolled back. Conversely, if a local
transaction has been started with *Note `START TRANSACTION': commit, no
XA statements can be used until the transaction has been committed or
rolled back.

Note that if an XA transaction is in the `ACTIVE' state, you cannot
issue any statements that cause an implicit commit. That would violate
the XA contract because you could not roll back the XA transaction. You
will receive the following error if you try to execute such a statement:

     ERROR 1399 (XAE07): XAER_RMFAIL: The command cannot be executed
     when global transaction is in the ACTIVE state

Statements to which the preceding remark applies are listed at *Note
implicit-commit::.


File: manual.info,  Node: sql-syntax-server-administration,  Next: sql-syntax-replication,  Prev: sql-syntax-transactions,  Up: sql-syntax

12.5 Database Administration Statements
=======================================

* Menu:

* account-management-sql::       Account Management Statements
* table-maintenance-sql::        Table Maintenance Statements
* backup-restore-sql::           Backup and Restore Statements
* plugin-sql::                   Plugin and User-Defined Function Statements
* set-option::                   `SET' Syntax
* show::                         `SHOW' Syntax
* other-administrative-sql::     Other Administrative Statements


File: manual.info,  Node: account-management-sql,  Next: table-maintenance-sql,  Prev: sql-syntax-server-administration,  Up: sql-syntax-server-administration

12.5.1 Account Management Statements
------------------------------------

* Menu:

* create-user::                  `CREATE USER' Syntax
* drop-user::                    `DROP USER' Syntax
* grant::                        `GRANT' Syntax
* rename-user::                  `RENAME USER' Syntax
* revoke::                       `REVOKE' Syntax
* set-password::                 `SET PASSWORD' Syntax

MySQL account information is stored in the tables of the `mysql'
database. This database and the access control system are discussed
extensively in *Note server-administration::, which you should consult
for additional details.

*Important*:

Some releases of MySQL introduce changes to the structure of the grant
tables to add new privileges or features. Whenever you update to a new
version of MySQL, you should update your grant tables to make sure that
they have the current structure so that you can take advantage of any
new capabilities. See *Note mysql-upgrade::.

MySQL Enterprise

In a production environment it is always prudent to examine any changes
to users' accounts. The MySQL Enterprise Monitor provides notification
whenever users' privileges are altered.  For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: create-user,  Next: drop-user,  Prev: account-management-sql,  Up: account-management-sql

12.5.1.1 `CREATE USER' Syntax
.............................

     CREATE USER USER [IDENTIFIED BY [PASSWORD] 'PASSWORD']
         [, USER [IDENTIFIED BY [PASSWORD] 'PASSWORD']] ...

The *Note `CREATE USER': create-user. statement creates new MySQL
accounts. To use it, you must have the global `CREATE USER' privilege
or the `INSERT' privilege for the `mysql' database. For each account,
*Note `CREATE USER': create-user. creates a new row in the `mysql.user'
table that has no privileges.  An error occurs if the account already
exists. Each account is named using the same format as for the *Note
`GRANT': grant. statement; for example, `'jeffrey'@'localhost''. If you
specify only the user name part of the account name, a host name part of
`'%'' is used. For additional information about specifying account
names, see *Note grant::.

The account can be given a password with the optional `IDENTIFIED BY'
clause. The USER value and the password are given the same way as for
the *Note `GRANT': grant.  statement. In particular, to specify the
password in plain text, omit the `PASSWORD' keyword. To specify the
password as the hashed value as returned by the `PASSWORD()' function,
include the `PASSWORD' keyword. See *Note grant::.

*Important*:

This statement may be recorded in a history file such as
`~/.mysql_history', which means that plaintext passwords may be read by
anyone having read access to such files.


File: manual.info,  Node: drop-user,  Next: grant,  Prev: create-user,  Up: account-management-sql

12.5.1.2 `DROP USER' Syntax
...........................

     DROP USER USER [, USER] ...

The *Note `DROP USER': drop-user. statement removes one or more MySQL
accounts. It removes privilege rows for the account from all grant
tables. To use this statement, you must have the global `CREATE USER'
privilege or the `DELETE' privilege for the `mysql' database. Each
account is named using the same format as for the *Note `GRANT': grant.
statement; for example, `'jeffrey'@'localhost''. If you specify only
the user name part of the account name, a host name part of `'%'' is
used. For additional information about specifying account names, see
*Note grant::.

With *Note `DROP USER': drop-user, you can remove an account and its
privileges as follows:

     DROP USER USER;

*Important*:

*Note `DROP USER': drop-user. does not automatically close any open
user sessions. Rather, in the event that a user with an open session is
dropped, the statement does not take effect until that user's session is
closed. Once the session is closed, the user is dropped, and that
user's next attempt to log in will fail. _This is by design_.

*Note `DROP USER': drop-user. does not automatically delete or
invalidate any database objects that the user created.  This applies to
tables, views, stored routines, triggers, and events.


File: manual.info,  Node: grant,  Next: rename-user,  Prev: drop-user,  Up: account-management-sql

12.5.1.3 `GRANT' Syntax
.......................

     GRANT
         PRIV_TYPE [(COLUMN_LIST)]
           [, PRIV_TYPE [(COLUMN_LIST)]] ...
         ON [OBJECT_TYPE] PRIV_LEVEL
         TO USER [IDENTIFIED BY [PASSWORD] 'PASSWORD']
             [, USER [IDENTIFIED BY [PASSWORD] 'PASSWORD']] ...
         [REQUIRE {NONE | SSL_OPTION [[AND] SSL_OPTION] ...}]
         [WITH WITH_OPTION [WITH_OPTION] ...]

     OBJECT_TYPE:
         TABLE
       | FUNCTION
       | PROCEDURE

     PRIV_LEVEL:
         *
       | *.*
       | DB_NAME.*
       | DB_NAME.TBL_NAME
       | TBL_NAME
       | DB_NAME.ROUTINE_NAME

     WITH_OPTION:
         GRANT OPTION
       | MAX_QUERIES_PER_HOUR COUNT
       | MAX_UPDATES_PER_HOUR COUNT
       | MAX_CONNECTIONS_PER_HOUR COUNT
       | MAX_USER_CONNECTIONS COUNT

     SSL_OPTION:
         SSL
       | X509
       | CIPHER 'CIPHER'
       | ISSUER 'ISSUER'
       | SUBJECT 'SUBJECT'

The *Note `GRANT': grant. statement enables system administrators to
create MySQL user accounts and to grant rights to accounts. To use
*Note `GRANT': grant, you must have the `GRANT OPTION' privilege, and
you must have the privileges that you are granting. The *Note `REVOKE':
revoke. statement is related and enables administrators to remove
account privileges.  To determine what privileges an account has, use
*Note `SHOW GRANTS': show-grants. See *Note revoke::, and *Note
show-grants::.

MySQL Enterprise

For automated notification of users with inappropriate privileges,
subscribe to the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The following table summarizes the allowable PRIV_TYPE privilege types
that can be specified for the *Note `GRANT': grant. and *Note `REVOKE':
revoke. statements. For additional information about these privileges,
see *Note privileges-provided::.

*Privilege*            *Meaning*
`ALL [PRIVILEGES]'     Grant all privileges at specified access level
                       except `GRANT OPTION'
`ALTER'                Enable use of *Note `ALTER TABLE': alter-table.
`ALTER ROUTINE'        Enable stored routines to be altered or dropped
`CREATE'               Enable database and table creation
`CREATE ROUTINE'       Enable stored routine creation
`CREATE TABLESPACE'    Enable tablespaces and log file groups to be
                       created, altered, or dropped
`CREATE TEMPORARY      Enable use of *Note `CREATE TEMPORARY TABLE':
TABLES'                create-table.
`CREATE USER'          Enable use of *Note `CREATE USER': create-user,
                       *Note `DROP USER': drop-user, *Note `RENAME
                       USER': rename-user, and *Note `REVOKE ALL
                       PRIVILEGES': revoke.
`CREATE VIEW'          Enable views to be created or altered
`DELETE'               Enable use of *Note `DELETE': delete.
`DROP'                 Enable databases, tables, and views to be dropped
`EVENT'                Enable use of events for the Event Scheduler
`EXECUTE'              Enable the user to execute stored routines
`FILE'                 Enable the user to cause the server to read or
                       write files
`GRANT OPTION'         Enable privileges to be granted to or removed
                       from other accounts
`INDEX'                Enable indexes to be created or dropped
`INSERT'               Enable use of *Note `INSERT': insert.
`LOCK TABLES'          Enable use of *Note `LOCK TABLES': lock-tables.
                       on tables for which you have the *Note `SELECT':
                       select.  privilege
`PROCESS'              Enable the user to see all processes with *Note
                       `SHOW PROCESSLIST': show-processlist.
`REFERENCES'           Not implemented
`RELOAD'               Enable use of *Note `FLUSH': flush. operations
`REPLICATION CLIENT'   Enable the user to ask where master or slave
                       servers are
`REPLICATION SLAVE'    Enable replication slaves to read binary log
                       events from the master
`SELECT'               Enable use of *Note `SELECT': select.
`SHOW DATABASES'       Enable *Note `SHOW DATABASES': show-databases. to
                       show all databases
`SHOW VIEW'            Enable use of *Note `SHOW CREATE VIEW':
                       show-create-view.
`SHUTDOWN'             Enable use of *Note `mysqladmin shutdown':
                       mysqladmin.
`SUPER'                Enable use of *Note `CHANGE MASTER TO':
                       change-master-to, *Note `KILL': kill, *Note
                       `PURGE BINARY LOGS': purge-binary-logs, and *Note
                       `SET GLOBAL': set-option. statements, the *Note
                       `mysqladmin debug': mysqladmin. command; allows
                       you to connect (once) even if `max_connections'
                       is reached
`TRIGGER'              Enable triggers to be created or dropped
`UPDATE'               Enable use of *Note `UPDATE': update.
`USAGE'                Synonym for `no privileges'

The `CREATE TABLESPACE' privilege was added in MySQL 6.0.7.

A trigger is associated with a table, so to create or drop a trigger,
you must have the `TRIGGER' privilege for the table, not the trigger.

`USAGE' can be specified when you want to create a user that has no
privileges, or to modify the `REQUIRE' or `WITH' clauses for an account
without changing its existing privileges.

MySQL account information is stored in the tables of the `mysql'
database. This database and the access control system are discussed
extensively in *Note server-administration::, which you should consult
for additional details.

*Important*:

Some releases of MySQL introduce changes to the structure of the grant
tables to add new privileges or features. Whenever you update to a new
version of MySQL, you should update your grant tables to make sure that
they have the current structure so that you can take advantage of any
new capabilities. See *Note mysql-upgrade::.

If the grant tables hold privilege rows that contain mixed-case
database or table names and the `lower_case_table_names' system
variable is set to a non-zero value, *Note `REVOKE': revoke. cannot be
used to revoke these privileges. It will be necessary to manipulate the
grant tables directly. (*Note `GRANT': grant. will not create such rows
when `lower_case_table_names' is set, but such rows might have been
created prior to setting the variable.)

Privileges can be granted at several levels, depending on the syntax
used for the `ON' clause. For *Note `REVOKE': revoke, the same `ON'
syntax specifies which privileges to take away. The examples shown here
include no `IDENTIFIED BY 'PASSWORD'' clause for brevity, but you
should include one if the account does not already exist to avoid
creating an account with no password.

*Global privileges*

Global privileges are administrative or apply to all databases on a
given server. To assign global privileges, use `ON *.*' syntax:

     GRANT ALL ON *.* TO 'someuser'@'somehost';
     GRANT SELECT, INSERT ON *.* TO 'someuser'@'somehost';

Privileges also are assigned at the global level if you use `ON *'
syntax and you have _not_ selected a default database.

The `CREATE TABLESPACE', `CREATE USER' `FILE', `PROCESS', `RELOAD',
`REPLICATION CLIENT', `REPLICATION SLAVE', `SHOW DATABASES',
`SHUTDOWN', and `SUPER' privileges are administrative and can only be
granted globally. Other privileges can be granted globally or at more
specific levels.

Global privileges are stored in the `mysql.user' table.

*Database privileges*

Database privileges apply to all objects in a given database. To assign
database-level privileges, use `ON DB_NAME.*' syntax:

     GRANT ALL ON mydb.* TO 'someuser'@'somehost';
     GRANT SELECT, INSERT ON mydb.* TO 'someuser'@'somehost';

Privileges also are assigned at the database level if you use `ON *'
syntax and you have selected a default database.

The `CREATE', `DROP', `EVENT', and `GRANT OPTION' privileges can be
specified at the database level. Table or routine privileges also can
be specified at the database level, in which case they apply to all
tables or routines in the database.

Database privileges are stored in the `mysql.db' and `mysql.host'
tables. *Note `GRANT': grant. and *Note `REVOKE': revoke. affect the
`db' table, but not the `host' table, which is rarely used.

*Table privileges*

Table privileges apply to all columns in a given table. To assign
table-level privileges, use `ON DB_NAME.TBL_NAME' syntax:

     GRANT ALL ON mydb.mytbl TO 'someuser'@'somehost';
     GRANT SELECT, INSERT ON mydb.mytbl TO 'someuser'@'somehost';

If you specify TBL_NAME rather than DB_NAME.TBL_NAME, the statement
applies to TBL_NAME in the default database. An error occurs if there
is no default database.

The allowable PRIV_TYPE values for a table are `ALTER', `CREATE VIEW',
`CREATE', `DELETE', `DROP', `GRANT OPTION', `INDEX', `INSERT',
`SELECT', `SHOW VIEW', `TRIGGER', and `UPDATE'.

Table privileges are stored in the `mysql.tables_priv' table.

*Column privileges*

Column privileges apply to single columns in a given table. Each
privilege to be granted at the column level must be followed by the
column or columns, enclosed within parentheses.

     GRANT SELECT (col1), INSERT (col1,col2) ON mydb.mytbl TO 'someuser'@'somehost';

The allowable PRIV_TYPE values for a column (that is, when you use a
COLUMN_LIST clause) are `INSERT', `SELECT', and `UPDATE'.

Column privileges are stored in the `mysql.columns_priv' table.

*Routine privileges*

The `ALTER ROUTINE', `CREATE ROUTINE', `EXECUTE', and `GRANT OPTION'
privileges apply to stored routines (procedures and functions). They
can be granted at the global and database levels. Except for `CREATE
ROUTINE', these privileges can be granted at the routine level for
individual routines.

     GRANT CREATE ROUTINE ON mydb.* TO 'someuser'@'somehost';
     GRANT EXECUTE ON PROCEDURE mydb.myproc TO 'someuser'@'somehost';

The allowable PRIV_TYPE values at the routine level are `ALTER ROUTINE',
`EXECUTE', and `GRANT OPTION'.  `CREATE ROUTINE' is not a routine-level
privilege because you must have this privilege to create a routine in
the first place.

Routine-level privileges are stored in the `mysql.procs_priv' table.

For the global, database, table, and routine levels, *Note `GRANT ALL':
grant.  assigns only the privileges that exist at the level you are
granting. For example, `GRANT ALL ON DB_NAME.*' is a database-level
statement, so it does not grant any global-only privileges such as
`FILE'.

The OBJECT_TYPE clause, if present, should be specified as `TABLE',
`FUNCTION', or `PROCEDURE' when the following object is a table, a
stored function, or a stored procedure.

The privileges for a database, table, column, or routine are formed
additively as the logical `OR' of the privileges at each of the
privilege levels. For example, if a user has a global `SELECT'
privilege, the privilege cannot be denied by an absence of the
privilege at the database, table, or column level. Details of the
privilege-checking procedure are presented in *Note request-access::.

MySQL enables you to grant privileges even on database objects that do
not exist. In such cases, the privileges to be granted must include the
`CREATE' privilege. _This behavior is by design_, and is intended to
enable the database administrator to prepare user accounts and
privileges for database objects that are to be created at a later time.

*Important*:

_MySQL does not automatically revoke any privileges when you drop a
database or table_. However, if you drop a routine, any routine-level
privileges granted for that routine are revoked.

The USER value indicates which MySQL account to grant the privileges
to. To accommodate granting rights to users from arbitrary hosts, MySQL
supports specifying the USER value in the form `USER_NAME@HOST_NAME'.
If a USER_NAME or HOST_NAME value is legal as an unquoted identifier,
you need not quote it. However, quotes are necessary to specify a
USER_NAME string containing special characters (such as ``-''), or a
HOST_NAME string containing special characters or wildcard characters
(such as ``%''); for example, `'test-user'@'%.com''. Quote the user
name and host name separately.

You can specify wildcards in the host name. For example,
`USER_NAME@'%.example.com'' applies to USER_NAME for any host in the
`example.com' domain, and `USER_NAME@'192.168.1.%'' applies to
USER_NAME for any host in the `192.168.1' class C subnet.

The simple form USER_NAME is a synonym for `USER_NAME@'%''.

_MySQL does not support wildcards in user names_. To refer to an
anonymous user, specify an account with an empty user name with the
*Note `GRANT': grant. statement:

     GRANT ALL ON test.* TO ''@'localhost' ...

In this case, any user who connects from the local host with the
correct password for the anonymous user will be allowed access, with
the privileges associated with the anonymous-user account.

For additional information about user and host values in account names,
see *Note account-names::.

To specify quoted values, quote database, table, column, and routine
names as identifiers, using backticks (```''). Quote user names and host
names as identifiers or as strings, using either backticks (```''),
single quotes (``'''), or double quotes (``"''). Quote passwords as
strings, using single quotes.

The ``_'' and ``%'' wildcards are allowed when specifying database
names in *Note `GRANT': grant. statements that grant privileges at the
global or database levels. This means, for example, that if you want to
use a ``_'' character as part of a database name, you should specify it
as ``\_'' in the *Note `GRANT': grant. statement, to prevent the user
from being able to access additional databases matching the wildcard
pattern; for example, `GRANT ... ON `foo\_bar`.* TO ...'.

*Warning*:

If you allow anonymous users to connect to the MySQL server, you should
also grant privileges to all local users as `USER_NAME@localhost'.
Otherwise, the anonymous user account for `localhost' in the
`mysql.user' table (created during MySQL installation) is used when
named users try to log in to the MySQL server from the local machine.
For details, see *Note connection-access::.

You can determine whether the preceding warning applies to you by
executing the following query, which lists any anonymous users:

     SELECT Host, User FROM mysql.user WHERE User='';

To avoid the problem just described, delete the local anonymous user
account using this statement:

     DROP USER ''@'localhost';

*Note `GRANT': grant. supports host names up to 60 characters long.
Database, table, column, and routine names can be up to 64 characters.
User names can be up to 16 characters.

*Warning*:

_The allowable length for user names cannot be changed by altering the
`mysql.user' table.  Attempting to do so results in unpredictable
behavior which may even make it impossible for users to log in to the
MySQL server_. You should never alter any of the tables in the `mysql'
database in any manner whatsoever except by means of the procedure
prescribed by MySQL AB that is described in *Note mysql-upgrade::.

If the `NO_AUTO_CREATE_USER' SQL mode is not enabled and the account
named in a *Note `GRANT': grant. statement does not exist in the
`mysql.user' table, *Note `GRANT': grant. creates it. If you specify no
`IDENTIFIED BY' clause or provide an empty password, the user has no
password. _This is very insecure._

If `NO_AUTO_CREATE_USER' is enabled and the account does not exist,
*Note `GRANT': grant. fails and does not create the account unless the
`IDENTIFIED BY' clause is given to provide a non-empty password.

When the `IDENTIFIED BY' clause is present and you have global grant
privileges, the password becomes the new password for the account, even
if the account exists and already has a password.

MySQL Enterprise

The MySQL Enterprise Monitor specifically guards against user accounts
with no passwords. To find out more, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Note `REVOKE': revoke. does not remove `mysql.user' table entries; you
must do that using *Note `DROP USER': drop-user. or *Note `DELETE':
delete.

Passwords can also be set with the *Note `SET PASSWORD': set-password.
statement. See *Note set-password::.

In the `IDENTIFIED BY' clause, the password should be given as the
literal password value. It is unnecessary to use the `PASSWORD()'
function as it is for the *Note `SET PASSWORD': set-password.
statement. For example:

     GRANT ... IDENTIFIED BY 'mypass';

If you do not want to send the password in clear text and you know the
hashed value that `PASSWORD()' would return for the password, you can
specify the hashed value preceded by the keyword `PASSWORD':

     GRANT ...
     IDENTIFIED BY PASSWORD '*6C8989366EAF75BB670AD8EA7A7FC1176A95CEF4';

The `WITH' clause is used for several purposes:

   * To enable a user to grant privileges to other users

   * To specify resource-use limitations on a user

   * To specify whether and how a user must use secure connections to
     the server

The `WITH GRANT OPTION' clause gives the user the ability to give to
other users any privileges the user has at the specified privilege
level. You should be careful to whom you give the `GRANT OPTION'
privilege, because two users with different privileges may be able to
combine privileges!

You cannot grant another user a privilege which you yourself do not
have; the `GRANT OPTION' privilege enables you to assign only those
privileges which you yourself possess.

Be aware that when you grant a user the `GRANT OPTION' privilege at a
particular privilege level, any privileges the user possesses (or may
be given in the future) at that level can also be granted by that user
to other users. Suppose that you grant a user the `INSERT' privilege on
a database. If you then grant the `SELECT' privilege on the database
and specify `WITH GRANT OPTION', that user can give to other users not
only the `SELECT' privilege, but also `INSERT'. If you then grant the
`UPDATE' privilege to the user on the database, the user can grant
`INSERT', `SELECT', and `UPDATE'.

For a non-administrative user, you should not grant the `ALTER'
privilege globally or for the `mysql' database. If you do that, the user
can try to subvert the privilege system by renaming tables!

For additional information about security risks associated with
particular privileges, see *Note privileges-provided::.

The `MAX_QUERIES_PER_HOUR COUNT', `MAX_UPDATES_PER_HOUR COUNT', and
`MAX_CONNECTIONS_PER_HOUR COUNT' options limit the number of queries,
updates, and logins a user can perform during any given one-hour
period. (Queries for which results are served from the query cache do
not count against the `MAX_QUERIES_PER_HOUR' limit.) If COUNT is `0'
(the default), this means that there is no limitation for that user.

The `MAX_USER_CONNECTIONS COUNT' option limits the maximum number of
simultaneous connections that the account can make. If COUNT is `0'
(the default), the `max_user_connections' system variable determines
the number of simultaneous connections for the account.

To specify any of these resource-limit options for an existing user
without affecting existing privileges, use `GRANT USAGE ON *.* ... WITH
MAX_...'.

For more information on restricting resources, see *Note
user-resources::.

MySQL can check X509 certificate attributes in addition to the usual
authentication that is based on the user name and password. To specify
SSL-related options for a MySQL account, use the `REQUIRE' clause of the
*Note `GRANT': grant. statement. (For background information on the use
of SSL with MySQL, see *Note secure-connections::.)

There are a number of different possibilities for limiting connection
types for a given account:

   * `REQUIRE NONE' indicates that the account has no SSL or X509
     requirements. This is the default if no SSL-related `REQUIRE'
     options are specified. Unencrypted connections are allowed if the
     user name and password are valid. However, encrypted connections
     can also be used, at the client's option, if the client has the
     proper certificate and key files. That is, the client need not
     specify any SSL command options, in which case the connection will
     be unencrypted. To use an encrypted connection, the client must
     specify either the `--ssl-ca' option, or all three of the
     `--ssl-ca', `--ssl-key', and `--ssl-cert' options.

   * The `REQUIRE SSL' option tells the server to allow only
     SSL-encrypted connections for the account.

          GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
            IDENTIFIED BY 'goodsecret' REQUIRE SSL;

     To connect, the client must specify the `--ssl-ca' option, and may
     additionally specify the `--ssl-key' and `--ssl-cert' options.

   * `REQUIRE X509' means that the client must have a valid certificate
     but that the exact certificate, issuer, and subject do not matter.
     The only requirement is that it should be possible to verify its
     signature with one of the CA certificates.

          GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
            IDENTIFIED BY 'goodsecret' REQUIRE X509;

     To connect, the client must specify the `--ssl-ca', `--ssl-key',
     and `--ssl-cert' options. This is also true for `ISSUER' and
     `SUBJECT' because those `REQUIRE' options imply `X509'.

   * `REQUIRE ISSUER 'ISSUER'' places the restriction on connection
     attempts that the client must present a valid X509 certificate
     issued by CA `'ISSUER''. If the client presents a certificate that
     is valid but has a different issuer, the server rejects the
     connection. Use of X509 certificates always implies encryption, so
     the `SSL' option is unnecessary in this case.

          GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
            IDENTIFIED BY 'goodsecret'
            REQUIRE ISSUER '/C=FI/ST=Some-State/L=Helsinki/
              O=MySQL Finland AB/CN=Tonu Samuel/Email=tonu@example.com';

     Note that the `'ISSUER'' value should be entered as a single
     string.

   * `REQUIRE SUBJECT 'SUBJECT'' places the restriction on connection
     attempts that the client must present a valid X509 certificate
     containing the subject SUBJECT. If the client presents a
     certificate that is valid but has a different subject, the server
     rejects the connection.

          GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
            IDENTIFIED BY 'goodsecret'
            REQUIRE SUBJECT '/C=EE/ST=Some-State/L=Tallinn/
              O=MySQL demo client certificate/
              CN=Tonu Samuel/Email=tonu@example.com';

     Note that the `'SUBJECT'' value should be entered as a single
     string.

   * `REQUIRE CIPHER 'CIPHER'' is needed to ensure that ciphers and key
     lengths of sufficient strength are used. SSL itself can be weak if
     old algorithms using short encryption keys are used. Using this
     option, you can ask that a specific cipher method is used to allow
     a connection.

          GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
            IDENTIFIED BY 'goodsecret'
            REQUIRE CIPHER 'EDH-RSA-DES-CBC3-SHA';

The `SUBJECT', `ISSUER', and `CIPHER' options can be combined in the
`REQUIRE' clause like this:

     GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
       IDENTIFIED BY 'goodsecret'
       REQUIRE SUBJECT '/C=EE/ST=Some-State/L=Tallinn/
         O=MySQL demo client certificate/
         CN=Tonu Samuel/Email=tonu@example.com'
       AND ISSUER '/C=FI/ST=Some-State/L=Helsinki/
         O=MySQL Finland AB/CN=Tonu Samuel/Email=tonu@example.com'
       AND CIPHER 'EDH-RSA-DES-CBC3-SHA';

The order of the options does not matter, but no option can be
specified twice. The `AND' keyword is optional between `REQUIRE'
options.

If you are using table, column, or routine privileges for even one
user, the server examines table, column, and routine privileges for all
users and this slows down MySQL a bit.  Similarly, if you limit the
number of queries, updates, or connections for any users, the server
must monitor these values.

The biggest differences between the standard SQL and MySQL versions of
*Note `GRANT': grant. are:

   * In MySQL, privileges are associated with the combination of a host
     name and user name and not with only a user name.

   * Standard SQL does not have global or database-level privileges,
     nor does it support all the privilege types that MySQL supports.

   * MySQL does not support the standard SQL `UNDER' privilege.

   * Standard SQL privileges are structured in a hierarchical manner.
     If you remove a user, all privileges the user has been granted are
     revoked. This is also true in MySQL if you use *Note `DROP USER':
     drop-user. See *Note drop-user::.

   * In standard SQL, when you drop a table, all privileges for the
     table are revoked. In standard SQL, when you revoke a privilege,
     all privileges that were granted based on that privilege are also
     revoked. In MySQL, privileges can be dropped only with explicit
     *Note `REVOKE': revoke. statements or by manipulating values
     stored in the MySQL grant tables.

   * In MySQL, it is possible to have the `INSERT' privilege for only
     some of the columns in a table. In this case, you can still
     execute *Note `INSERT': insert. statements on the table, provided
     that you omit those columns for which you do not have the `INSERT'
     privilege. The omitted columns are set to their implicit default
     values if strict SQL mode is not enabled. In strict mode, the
     statement is rejected if any of the omitted columns have no
     default value. (Standard SQL requires you to have the `INSERT'
     privilege on all columns.) *Note server-sql-mode::, discusses
     strict mode. *Note data-type-defaults::, discusses implicit
     default values.


File: manual.info,  Node: rename-user,  Next: revoke,  Prev: grant,  Up: account-management-sql

12.5.1.4 `RENAME USER' Syntax
.............................

     RENAME USER OLD_USER TO NEW_USER
         [, OLD_USER TO NEW_USER] ...

The *Note `RENAME USER': rename-user. statement renames existing MySQL
accounts. To use it, you must have the global `CREATE USER' privilege
or the `UPDATE' privilege for the `mysql' database. An error occurs if
any old account does not exist or any new account exists. Each account
is named using the same format as for the *Note `GRANT': grant.
statement; for example, `'jeffrey'@'localhost''. If you specify only
the user name part of the account name, a host name part of `'%'' is
used. For additional information about specifying account names, see
*Note grant::.

*Note `RENAME USER': rename-user. does not automatically migrate any
database objects that the user created, nor does it migrate any
privileges that the user had prior to the renaming. This applies to
tables, views, stored routines, triggers, and events.


File: manual.info,  Node: revoke,  Next: set-password,  Prev: rename-user,  Up: account-management-sql

12.5.1.5 `REVOKE' Syntax
........................

     REVOKE
         PRIV_TYPE [(COLUMN_LIST)]
           [, PRIV_TYPE [(COLUMN_LIST)]] ...
         ON [OBJECT_TYPE] PRIV_LEVEL
         FROM USER [, USER] ...

     REVOKE ALL PRIVILEGES, GRANT OPTION
         FROM USER [, USER] ...

The *Note `REVOKE': revoke. statement enables system administrators to
revoke privileges from MySQL accounts.  Each account is named using the
same format as for the *Note `GRANT': grant. statement; for example,
`'jeffrey'@'localhost''. If you specify only the user name part of the
account name, a host name part of `'%'' is used. For details on the
levels at which privileges exist, the allowable PRIV_TYPE and
PRIV_LEVEL values, and the syntax for specifying users and passwords,
see *Note grant::

To use the first *Note `REVOKE': revoke. syntax, you must have the
`GRANT OPTION' privilege, and you must have the privileges that you are
revoking.

To revoke all privileges, use the second syntax, which drops all
global, database, table, column, and routine privileges for the named
user or users:

     REVOKE ALL PRIVILEGES, GRANT OPTION FROM USER [, USER] ...

To use this *Note `REVOKE': revoke. syntax, you must have the global
`CREATE USER' privilege or the `UPDATE' privilege for the `mysql'
database.

*Note `REVOKE': revoke. removes privileges, but does not drop
`mysql.user' table entries. To remove a user account entirely, use
*Note `DROP USER': drop-user. (see *Note drop-user::) or *Note
`DELETE': delete.

If the grant tables hold privilege rows that contain mixed-case
database or table names and the `lower_case_table_names' system
variable is set to a non-zero value, *Note `REVOKE': revoke. cannot be
used to revoke these privileges. It will be necessary to manipulate the
grant tables directly. (*Note `GRANT': grant. will not create such rows
when `lower_case_table_names' is set, but such rows might have been
created prior to setting the variable.)

To verify an account's privileges after a *Note `REVOKE': revoke.
operation, use *Note `SHOW GRANTS': show-grants. See *Note
show-grants::.


File: manual.info,  Node: set-password,  Prev: revoke,  Up: account-management-sql

12.5.1.6 `SET PASSWORD' Syntax
..............................

     SET PASSWORD [FOR USER] =
         {
             PASSWORD('SOME PASSWORD')
           | OLD_PASSWORD('SOME PASSWORD')
           | 'ENCRYPTED PASSWORD'
         }

The *Note `SET PASSWORD': set-password. statement assigns a password to
an existing MySQL user account.

If the password is specified using the `PASSWORD()' or `OLD_PASSWORD()'
function, the literal text of the password should be given. If the
password is specified without using either function, the password
should be the already-encrypted password value as returned by
`PASSWORD()'.

With no `FOR' clause, this statement sets the password for the current
user. Any client that has connected to the server using a non-anonymous
account can change the password for that account.

With a `FOR' clause, this statement sets the password for a specific
account on the current server host. Only clients that have the *Note
`UPDATE': update.  privilege for the `mysql' database can do this.  The
USER value should be given in `USER_NAME@HOST_NAME' format, where
USER_NAME and HOST_NAME are exactly as they are listed in the `User' and
`Host' columns of the `mysql.user' table entry. For example, if you had
an entry with `User' and `Host' column values of `'bob'' and
`'%.loc.gov'', you would write the statement like this:

     SET PASSWORD FOR 'bob'@'%.loc.gov' = PASSWORD('NEWPASS');

That is equivalent to the following statements:

     UPDATE mysql.user SET Password=PASSWORD('NEWPASS')
       WHERE User='bob' AND Host='%.loc.gov';
     FLUSH PRIVILEGES;

*Note*:

If you are connecting to a MySQL 4.1 or later server using a pre-4.1
client program, do not use the preceding *Note `SET PASSWORD':
set-password. or *Note `UPDATE': update. statement without reading
*Note password-hashing::, first. The password format changed in MySQL
4.1, and under certain circumstances it is possible that if you change
your password, you might not be able to connect to the server afterward.

You can see which account the server authenticated you as by executing
`SELECT CURRENT_USER()'.

MySQL Enterprise

For automated notification of users without passwords, subscribe to the
MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: table-maintenance-sql,  Next: backup-restore-sql,  Prev: account-management-sql,  Up: sql-syntax-server-administration

12.5.2 Table Maintenance Statements
-----------------------------------

* Menu:

* analyze-table::                `ANALYZE TABLE' Syntax
* check-table::                  `CHECK TABLE' Syntax
* checksum-table::               `CHECKSUM TABLE' Syntax
* optimize-table::               `OPTIMIZE TABLE' Syntax
* repair-table::                 `REPAIR TABLE' Syntax


File: manual.info,  Node: analyze-table,  Next: check-table,  Prev: table-maintenance-sql,  Up: table-maintenance-sql

12.5.2.1 `ANALYZE TABLE' Syntax
...............................

     ANALYZE [NO_WRITE_TO_BINLOG | LOCAL] TABLE
         TBL_NAME [, TBL_NAME] ...

*Note `ANALYZE TABLE': analyze-table. analyzes and stores the key
distribution for a table. During the analysis, the table is locked with
a read lock for `MyISAM'. For `InnoDB' the table is locked with a write
lock.  This statement works with `MyISAM', and `InnoDB' tables. For
`MyISAM' tables, this statement is equivalent to using *Note `myisamchk
--analyze': myisamchk.

For more information on how the analysis works within `InnoDB', see
*Note innodb-restrictions::.

MySQL Enterprise

For expert advice on optimizing tables subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

MySQL uses the stored key distribution to decide the order in which
tables should be joined when you perform a join on something other than
a constant. In addition, key distributions can be used when deciding
which indexes to use for a specific table within a query.

This statement requires `SELECT' and `INSERT' privileges for the table.

Beginning with MySQL 6.0.8, *Note `ANALYZE TABLE': analyze-table. is
also supported for partitioned tables. Also beginning with MySQL 6.0.8,
you can use `ALTER TABLE ...  ANALYZE PARTITION' to analyze one or more
partitions; for more information, see *Note alter-table::, and *Note
partitioning-maintenance::.

*Note `ANALYZE TABLE': analyze-table. returns a result set with the
following columns.

*Column*    *Value*
`Table'     The table name
`Op'        Always `analyze'
`Msg_type'  `status', `error', `info', or `warning'
`Msg_text'  An informational message

You can check the stored key distribution with the *Note `SHOW INDEX':
show-index. statement. See *Note show-index::.

If the table has not changed since the last *Note `ANALYZE TABLE':
analyze-table. statement, the table is not analyzed again.

By default, *Note `ANALYZE TABLE': analyze-table.  statements are
written to the binary log so that they will be replicated to
replication slaves. Logging can be suppressed with the optional
`NO_WRITE_TO_BINLOG' keyword or its alias `LOCAL'.


File: manual.info,  Node: check-table,  Next: checksum-table,  Prev: analyze-table,  Up: table-maintenance-sql

12.5.2.2 `CHECK TABLE' Syntax
.............................

     CHECK TABLE TBL_NAME [, TBL_NAME] ... [OPTION] ...

     OPTION = {FOR UPGRADE | QUICK | FAST | MEDIUM | EXTENDED | CHANGED}

*Note `CHECK TABLE': check-table. checks a table or tables for errors.
*Note `CHECK TABLE': check-table.  works for `MyISAM', `InnoDB',
`ARCHIVE', and `CSV' tables.  For `MyISAM' tables, the key statistics
are updated as well.

To check a table, you must have some privilege for it.

*Note `CHECK TABLE': check-table. can also check views for problems,
such as tables that are referenced in the view definition that no
longer exist.

Beginning with MySQL 6.0.6, *Note `CHECK TABLE': check-table. is also
supported for partitioned tables. Also beginning with MySQL 6.0.6, you
can use `ALTER TABLE ...  CHECK PARTITION' to check one or more
partitions; for more information, see *Note alter-table::, and *Note
partitioning-maintenance::.

*Note `CHECK TABLE': check-table. returns a result set with the
following columns.

*Column*    *Value*
`Table'     The table name
`Op'        Always `check'
`Msg_type'  `status', `error', `info', or `warning'
`Msg_text'  An informational message

Note that the statement might produce many rows of information for each
checked table. The last row has a `Msg_type' value of `status' and the
`Msg_text' normally should be `OK'. If you don't get `OK', or `Table is
already up to date' you should normally run a repair of the table. See
*Note table-maintenance::. `Table is already up to date' means that the
storage engine for the table indicated that there was no need to check
the table.

The `FOR UPGRADE' option checks whether the named tables are compatible
with the current version of MySQL.  With `FOR UPGRADE', the server
checks each table to determine whether there have been any incompatible
changes in any of the table's data types or indexes since the table was
created. If not, the check succeeds. Otherwise, if there is a possible
incompatibility, the server runs a full check on the table (which might
take some time). If the full check succeeds, the server marks the
table's `.frm' file with the current MySQL version number. Marking the
`.frm' file ensures that further checks for the table with the same
version of the server will be fast.

Incompatibilities might occur because the storage format for a data
type has changed or because its sort order has changed. Our aim is to
avoid these changes, but occasionally they are necessary to correct
problems that would be worse than an incompatibility between releases.

Currently, `FOR UPGRADE' discovers these incompatibilities:

   * The indexing order for end-space in *Note `TEXT': blob. columns for
     `InnoDB' and `MyISAM' tables changed between MySQL 4.1 and 5.0.

   * The storage method of the new *Note `DECIMAL': numeric-types. data
     type changed between MySQL 5.0.3 and 5.0.5.

   * As of MySQL 6.0.6, if your table was created by a different
     version of the MySQL server than the one you are currently
     running, `FOR UPGRADE' indicates that the table has an `.frm' file
     with an incompatible version. In this case, the result set returned
     by *Note `CHECK TABLE': check-table. contains a line with a
     `Msg_type' value of `error' and a `Msg_text' value of `Table
     upgrade required. Please do "REPAIR TABLE `TBL_NAME`" to fix it!'

   * Changes are sometimes made to character sets or collations that
     require table indexes to be rebuilt. For details about these
     changes and when `FOR UPGRADE' detects them, see *Note
     checking-index-changes::.

The other check options that can be given are shown in the following
table. These options are passed to the storage engine, which may use
them or not. `MyISAM' uses them; they are ignored for `InnoDB' tables
and views.

*Type*      *Meaning*
`QUICK'     Do not scan the rows to check for incorrect links.
`FAST'      Check only tables that have not been closed properly.
`CHANGED'   Check only tables that have been changed since the last
            check or that have not been closed properly.
`MEDIUM'    Scan rows to verify that deleted links are valid. This also
            calculates a key checksum for the rows and verifies this
            with a calculated checksum for the keys.
`EXTENDED'  Do a full key lookup for all keys for each row. This ensures
            that the table is 100% consistent, but takes a long time.

If none of the options `QUICK', `MEDIUM', or `EXTENDED' are specified,
the default check type for dynamic-format `MyISAM' tables is `MEDIUM'.
This has the same result as running *Note `myisamchk --medium-check
TBL_NAME': myisamchk. on the table. The default check type also is
`MEDIUM' for static-format `MyISAM' tables, unless `CHANGED' or `FAST'
is specified. In that case, the default is `QUICK'. The row scan is
skipped for `CHANGED' and `FAST' because the rows are very seldom
corrupted.

You can combine check options, as in the following example that does a
quick check on the table to determine whether it was closed properly:

     CHECK TABLE test_table FAST QUICK;

*Note*:

In some cases, *Note `CHECK TABLE': check-table.  changes the table.
This happens if the table is marked as `corrupted' or `not closed
properly' but *Note `CHECK TABLE': check-table. does not find any
problems in the table. In this case, *Note `CHECK TABLE': check-table.
marks the table as okay.

If a table is corrupted, it is most likely that the problem is in the
indexes and not in the data part. All of the preceding check types
check the indexes thoroughly and should thus find most errors.

If you just want to check a table that you assume is okay, you should
use no check options or the `QUICK' option. The latter should be used
when you are in a hurry and can take the very small risk that `QUICK'
does not find an error in the data file. (In most cases, under normal
usage, MySQL should find any error in the data file. If this happens,
the table is marked as `corrupted' and cannot be used until it is
repaired.)

`FAST' and `CHANGED' are mostly intended to be used from a script (for
example, to be executed from `cron') if you want to check tables from
time to time. In most cases, `FAST' is to be preferred over `CHANGED'.
(The only case when it is not preferred is when you suspect that you
have found a bug in the `MyISAM' code.)

`EXTENDED' is to be used only after you have run a normal check but
still get strange errors from a table when MySQL tries to update a row
or find a row by key. This is very unlikely if a normal check has
succeeded.

Use of *Note `CHECK TABLE ... EXTENDED': check-table. might influence
the execution plan generated by the query optimizer.

Some problems reported by *Note `CHECK TABLE': check-table. cannot be
corrected automatically:

   * `Found row where the auto_increment column has the value 0'.

     This means that you have a row in the table where the
     `AUTO_INCREMENT' index column contains the value 0. (It is
     possible to create a row where the `AUTO_INCREMENT' column is 0 by
     explicitly setting the column to 0 with an *Note `UPDATE': update.
     statement.)

     This is not an error in itself, but could cause trouble if you
     decide to dump the table and restore it or do an *Note `ALTER
     TABLE': alter-table. on the table. In this case, the
     `AUTO_INCREMENT' column changes value according to the rules of
     `AUTO_INCREMENT' columns, which could cause problems such as a
     duplicate-key error.

     To get rid of the warning, simply execute an *Note `UPDATE':
     update. statement to set the column to some value other than 0.

   * If *Note `CHECK TABLE': check-table. finds a problem for an
     `InnoDB' table, the server shuts down to prevent error
     propagation. Details of the error will be written to the error log.


File: manual.info,  Node: checksum-table,  Next: optimize-table,  Prev: check-table,  Up: table-maintenance-sql

12.5.2.3 `CHECKSUM TABLE' Syntax
................................

     CHECKSUM TABLE TBL_NAME [, TBL_NAME] ... [ QUICK | EXTENDED ]

*Note `CHECKSUM TABLE': checksum-table. reports a table checksum. This
statement requires the `SELECT' privilege for the table.

With `QUICK', the live table checksum is reported if it is available,
or `NULL' otherwise. This is very fast. A live checksum is enabled by
specifying the `CHECKSUM=1' table option when you create the table;
currently, this is supported only for `MyISAM' tables. See *Note
create-table::.

With `EXTENDED', the entire table is read row by row and the checksum
is calculated. This can be very slow for large tables.

If neither `QUICK' nor `EXTENDED' is specified, MySQL returns a live
checksum if the table storage engine supports it and scans the table
otherwise.

For a non-existent table, *Note `CHECKSUM TABLE': checksum-table.
returns `NULL' and generates a warning.

The checksum value depends on the table row format. If the row format
changes, the checksum also changes. For example, the storage format for
*Note `VARCHAR': char.  changed between MySQL 4.1 and 5.0, so if a 4.1
table is upgraded to MySQL 5.0, the checksum value may change.

*Important*:

If the checksums for two tables are different, then the tables are
different in some way. However, the fact that two tables produce the
same checksum does _not_ mean that the tables are identical.


File: manual.info,  Node: optimize-table,  Next: repair-table,  Prev: checksum-table,  Up: table-maintenance-sql

12.5.2.4 `OPTIMIZE TABLE' Syntax
................................

     OPTIMIZE [NO_WRITE_TO_BINLOG | LOCAL] TABLE
         TBL_NAME [, TBL_NAME] ...

*Note `OPTIMIZE TABLE': optimize-table. should be used if you have
deleted a large part of a table or if you have made many changes to a
table with variable-length rows (tables that have *Note `VARCHAR': char,
*Note `VARBINARY': binary-varbinary, *Note `BLOB': blob, or *Note
`TEXT': blob. columns). Deleted rows are maintained in a linked list
and subsequent *Note `INSERT': insert. operations reuse old row
positions. You can use *Note `OPTIMIZE TABLE': optimize-table. to
reclaim the unused space and to defragment the data file.

This statement requires `SELECT' and `INSERT' privileges for the table.

Beginning with MySQL 6.0.6, *Note `OPTIMIZE TABLE': optimize-table. is
also supported for partitioned tables. Also beginning with MySQL 6.0.6,
you can use `ALTER TABLE ...  OPTIMIZE PARTITION' to optimize one or
more partitions; for more information, see *Note alter-table::, and
*Note partitioning-maintenance::.

In most setups, you need not run *Note `OPTIMIZE TABLE':
optimize-table. at all. Even if you do a lot of updates to
variable-length rows, it is not likely that you need to do this more
than once a week or month and only on certain tables.

*Note `OPTIMIZE TABLE': optimize-table. works _only_ for `MyISAM',
`InnoDB', and `ARCHIVE' tables. It does _not_ work for tables created
using any other storage engine supported in MySQL 6.0.

For `MyISAM' tables, *Note `OPTIMIZE TABLE': optimize-table. works as
follows:

  1. If the table has deleted or split rows, repair the table.

  2. If the index pages are not sorted, sort them.

  3. If the table's statistics are not up to date (and the repair could
     not be accomplished by sorting the index), update them.

For `InnoDB' tables, *Note `OPTIMIZE TABLE': optimize-table. is mapped
to *Note `ALTER TABLE': alter-table, which rebuilds the table to update
index statistics and free unused space in the clustered index.
Beginning with MySQL 6.0.6, this is displayed in the output of *Note
`OPTIMIZE TABLE': optimize-table.  when you run it on an `InnoDB'
table, as shown here:

     mysql> OPTIMIZE TABLE foo;
     +----------+----------+----------+-------------------------------------------------------------------+
     | Table    | Op       | Msg_type | Msg_text                                                          |
     +----------+----------+----------+-------------------------------------------------------------------+
     | test.foo | optimize | note     | Table does not support optimize, doing recreate + analyze instead |
     | test.foo | optimize | status   | OK                                                                |
     +----------+----------+----------+-------------------------------------------------------------------+

You can make *Note `OPTIMIZE TABLE': optimize-table. work on other
storage engines by starting *Note `mysqld': mysqld.  with the
`--skip-new' or `--safe-mode' option. In this case, *Note `OPTIMIZE
TABLE': optimize-table. is just mapped to *Note `ALTER TABLE':
alter-table.

*Note `OPTIMIZE TABLE': optimize-table. returns a result set with the
following columns.

*Column*    *Value*
`Table'     The table name
`Op'        Always `optimize'
`Msg_type'  `status', `error', `info', or `warning'
`Msg_text'  An informational message

Note that MySQL locks the table during the time *Note `OPTIMIZE TABLE':
optimize-table. is running.

By default, *Note `OPTIMIZE TABLE': optimize-table.  statements are
written to the binary log so that they will be replicated to
replication slaves. Logging can be suppressed with the optional
`NO_WRITE_TO_BINLOG' keyword or its alias `LOCAL'.

*Note `OPTIMIZE TABLE': optimize-table. does not sort R-tree indexes,
such as spatial indexes on `POINT' columns. (Bug#23578
(http://bugs.mysql.com/23578))


File: manual.info,  Node: repair-table,  Prev: optimize-table,  Up: table-maintenance-sql

12.5.2.5 `REPAIR TABLE' Syntax
..............................

     REPAIR [NO_WRITE_TO_BINLOG | LOCAL] TABLE
         TBL_NAME [, TBL_NAME] ...
         [QUICK] [EXTENDED] [USE_FRM]

*Note `REPAIR TABLE': repair-table. repairs a possibly corrupted table.
By default, it has the same effect as *Note `myisamchk --recover
TBL_NAME': myisamchk.  *Note `REPAIR TABLE': repair-table. works for
`MyISAM', `ARCHIVE', and `CSV' tables. See *Note
myisam-storage-engine::, and *Note archive-storage-engine::, and *Note
csv-storage-engine::

This statement requires `SELECT' and `INSERT' privileges for the table.

Beginning with MySQL 6.0.6, *Note `REPAIR TABLE': repair-table. is also
supported for partitioned tables.  However, the `USE_FRM' option cannot
be used with this statement on a partitioned table.

Also beginning with MySQL 6.0.6, you can use `ALTER TABLE ... REPAIR
PARTITION' to repair one or more partitions; for more information, see
*Note alter-table::, and *Note partitioning-maintenance::.

Normally, you should never have to run *Note `REPAIR TABLE':
repair-table. However, if disaster strikes, this statement is very
likely to get back all your data from a `MyISAM' table. If your tables
become corrupted often, you should try to find the reason for it, to
eliminate the need to use *Note `REPAIR TABLE': repair-table. See *Note
crashing::, and *Note myisam-table-problems::.

*Caution*:

It is best to make a backup of a table before performing a table repair
operation; under some circumstances the operation might cause data
loss. Possible causes include but are not limited to file system errors.

*Warning*:

If the server dies during a *Note `REPAIR TABLE': repair-table.
operation, it is essential after restarting it that you immediately
execute another *Note `REPAIR TABLE': repair-table. statement for the
table before performing any other operations on it. In the worst case,
you might have a new clean index file without information about the
data file, and then the next operation you perform could overwrite the
data file. This is an unlikely but possible scenario that underscores
the value of making a backup first.

*Note `REPAIR TABLE': repair-table. returns a result set with the
following columns.

*Column*    *Value*
`Table'     The table name
`Op'        Always `repair'
`Msg_type'  `status', `error', `info', or `warning'
`Msg_text'  An informational message

The *Note `REPAIR TABLE': repair-table. statement might produce many
rows of information for each repaired table. The last row has a
`Msg_type' value of `status' and `Msg_test' normally should be `OK'. If
you do not get `OK' for a `MyISAM' table, you should try repairing it
with *Note `myisamchk --safe-recover': myisamchk. (*Note `REPAIR
TABLE': repair-table. does not implement all the options of *Note
`myisamchk': myisamchk.) With *Note `myisamchk --safe-recover':
myisamchk, you can also use options that *Note `REPAIR TABLE':
repair-table. does not support, such as `--max-record-length'.

If you use the `QUICK' option, *Note `REPAIR TABLE': repair-table.
tries to repair only the index tree. This type of repair is like that
done by *Note `myisamchk --recover --quick': myisamchk.

If you use the `EXTENDED' option, MySQL creates the index row by row
instead of creating one index at a time with sorting. This type of
repair is like that done by *Note `myisamchk --safe-recover': myisamchk.

The `USE_FRM' option is available for use if the `.MYI' index file is
missing or if its header is corrupted. This option tells MySQL not to
trust the information in the `.MYI' file header and to re-create it
using information from the `.frm' file. This kind of repair cannot be
done with *Note `myisamchk': myisamchk.

*Note*:

Use the `USE_FRM' option _only_ if you cannot use regular `REPAIR'
modes! Telling the server to ignore the `.MYI' file makes important
table metadata stored in the `.MYI' unavailable to the repair process,
which can have deleterious consequences:

   * The current `AUTO_INCREMENT' value is lost.

   * The link to deleted records in the table is lost, which means that
     free space for deleted records will remain unoccupied thereafter.

   * The `.MYI' header indicates whether the table is compressed. If
     the server ignores this information, it cannot tell that a table
     is compressed and repair can cause change or loss of table
     contents. This means that `USE_FRM' should not be used with
     compressed tables. That should not be necessary, anyway:
     Compressed tables are read only, so they should not become corrupt.

*Caution*:

As of MySQL 6.0.6, if you use `USE_FRM' for a table that was created by
a different version of the MySQL server than the one you are currently
running, *Note `REPAIR TABLE': repair-table. will not attempt to repair
the table. In this case, the result set returned by *Note `REPAIR
TABLE': repair-table. contains a line with a `Msg_type' value of
`error' and a `Msg_text' value of `Failed repairing incompatible .FRM
file'.

Prior to MySQL 6.0.6, _do not use_ `USE_FRM' if your table was created
by a different version of the MySQL server. Doing so risks the loss of
all rows in the table. It is particularly dangerous to use `USE_FRM'
after the server returns this message:

     Table upgrade required. Please do
     "REPAIR TABLE `TBL_NAME`" to fix it!

If `USE_FRM' is _not_ used, *Note `REPAIR TABLE': repair-table. checks
the table to see whether an upgrade is required. If so, it performs the
upgrade, following the same rules as *Note `CHECK TABLE ... FOR
UPGRADE': check-table. See *Note check-table::, for more information.
As of MySQL 6.0.6, *Note `REPAIR TABLE': repair-table. without
`USE_FRM' upgrades the `.frm' file to the current version.

By default, *Note `REPAIR TABLE': repair-table.  statements are written
to the binary log so that they will be replicated to replication
slaves. Logging can be suppressed with the optional
`NO_WRITE_TO_BINLOG' keyword or its alias `LOCAL'.


File: manual.info,  Node: backup-restore-sql,  Next: plugin-sql,  Prev: table-maintenance-sql,  Up: sql-syntax-server-administration

12.5.3 Backup and Restore Statements
------------------------------------

* Menu:

* backup-database::              `BACKUP DATABASE' Syntax
* purge-backup-logs::            `PURGE BACKUP LOGS' Syntax
* restore::                      `RESTORE' Syntax


File: manual.info,  Node: backup-database,  Next: purge-backup-logs,  Prev: backup-restore-sql,  Up: backup-restore-sql

12.5.3.1 `BACKUP DATABASE' Syntax
.................................

     BACKUP {DATABASE | SCHEMA}
         { * | DB_NAME [, DB_NAME] ... }
         TO 'IMAGE_FILE_NAME'
         [WITH COMPRESSION
           [COMPRESSION_ALGORITHM [=] ALGORITHM_NAME]]

This statement backs up one or more databases and writes the backup
contents to an image file (a file containing database contents). The
file must be named as a literal string. The file can be a regular file,
in which case, it must not already exist.  As of MySQL 6.0.6, the file
can be an existing FIFO on Unix. The file is written to the server
host. Its location must be in a directory where the server can create
and write files. If the `secure_backup_file_priv' system variable is
set to a non-empty directory name, the image file must be located in
that directory. (Before MySQL 6.0.11, `secure_file_priv' applies
instead.)

As of MySQL 6.0.7, the `backupdir' system variable value is the default
image file directory for *Note `BACKUP DATABASE': backup-database.
operations. If an image file is named as a relative path name, it is
interpreted relative to the value of `backupdir'. The default value is
the data directory. Before MySQL 6.0.7, the file should be specified as
a full path name.

*Note `BACKUP DATABASE': backup-database. requires the `SUPER' and
`FILE' privileges, as well as the `SELECT' privilege for all objects to
be backed up.

The databases to back up may be specified using `*' to name all
databases, or using a comma-separated list of one or more names. All
specified databases are backed up to the same image file. If databases
are named, no name can appear more than once, and all the databases
must exist.

     BACKUP DATABASE * TO '/tmp/all.backup';
     BACKUP DATABASE world TO '/tmp/world.backup';
     BACKUP DATABASE db1, db2 TO '/tmp/db1-db2.backup';

The resulting image file contains information about which databases it
contains and can be used later with a *Note `RESTORE': restore.
statement to restore the contents of those databases to their state at
the time of the backup operation.

Upon successful completion, the *Note `BACKUP DATABASE':
backup-database. statement returns a result set with the backup number.
Warnings produced during the operation can be displayed with *Note
`SHOW WARNINGS': show-warnings. If the backup operation fails, it
returns an error and any file created by the operation is deleted.

     mysql> BACKUP DATABASE test TO '/tmp/world.backup';
     +-----------+
     | backup_id |
     +-----------+
     | 8         |
     +-----------+

While the operation is in progress, it can be monitored as described in
*Note backup-database-restore-monitoring::.

As of MySQL 6.0.7, you can use the `WITH COMPRESSION' clause to cause
*Note `BACKUP DATABASE': backup-database. to compress the backup. This
reduces the image size. The optional `COMPRESSION_ALGORITHM' clause may
be given when using `WITH COMPRESSION'. The only allowable algorithm
name is `gzip', which is also the default. `gzip' compression is the
same as that done by the `gzip' command-line utility; it follows the
conventions described as `http://www.faqs.org/rfcs/rfc1952.html'.

If `WITH COMPRESSION' is given, the entire backup is compressed. It is
not possible to selectively compress some databases but not others
within a single backup operation.

Use of compression does not cause *Note `BACKUP DATABASE':
backup-database. to modify the given image file name. We recommend that
you use an appropriate suffix. For example, if you name a backup image
`mybackup.bak' normally, name it `mybackup.bak.gz' instead if you
specify `WITH COMPRESSION'.

*Note `RESTORE': restore. detects whether a backup image is compressed
and uncompresses it automatically as necessary.

It is possible to manually compress and uncompressed image or
uncompress a compressed image by using a `gzip'-compatible tool. In
either case, *Note `RESTORE': restore. will detect whether the image
needs to be compressed.

For a MySQL server to be able to produce compressed images, it must be
compiled with `zlib' support (see *Note configure-options::). If `WITH
COMPRESSION' is specified and `zlib' support is not present, *Note
`BACKUP DATABASE': backup-database. fails with an error.

If you produce a compressed image with a server that has `zlib'
support, the image cannot be restored by another server unless that
server also has `zlib' support, or unless you manually uncompress the
image first. Otherwise, the *Note `RESTORE': restore. operation will
fail with an error.

Use of compression may make backup and restore operations faster by
reducing the amount of disk I/O. There is some tradeoff due to the
increased CPU load required for compression and uncompression
calculations, but in general we expect this to be outweighed by the
time savings from reduced I/O.

*Note `BACKUP DATABASE': backup-database. backs up database and table
definitions, table data, stored routines, triggers, events, and views.
`TEMPORARY' tables are not included. Tablespace backup support is
limited to the `Falcon' storage engine. Privileges are not saved before
MySQL 6.0.7. As of 6.0.7, privileges for backed-up databases are saved.
This includes privileges at the database level and below (table,
column, routine). Global privileges are not saved. For additional
information about how privileges are backed up, see *Note
backup-database-restore-quick-guide::.

For anything else not explicitly listed, assume that it is not backed
up. This includes but is not limited to items such as UDF definitions
and files, logs, and option files.

The *Note `BACKUP DATABASE': backup-database. statement does not back
up the `mysql' or `INFORMATION_SCHEMA' databases. The statement
silently ignores them if you use the `*' database selector syntax. Do
not include them in the list of names if you specify database names
explicitly. To back up the `mysql' database, you can use the *Note
`mysqldump': mysqldump. program. For an example backup strategy that
combines *Note `BACKUP DATABASE': backup-database. with *Note
`mysqldump': mysqldump, see *Note backup-database-restore-quick-guide::.

The *Note `BACKUP DATABASE': backup-database. statement is not written
to the binary log and does not replicate to slave servers.

For general information about *Note `BACKUP DATABASE': backup-database.
and *Note `RESTORE': restore, see *Note backup-database-restore::.
Limitations on the use of these statements are discussed in *Note
backup-database-restore-restrictions::.

*Note `BACKUP DATABASE': backup-database. was added in MySQL 6.0.5.


File: manual.info,  Node: purge-backup-logs,  Next: restore,  Prev: backup-database,  Up: backup-restore-sql

12.5.3.2 `PURGE BACKUP LOGS' Syntax
...................................

     PURGE BACKUP LOGS
         ] TO ID | BEFORE DATETIME_EXPR ]

The *Note `PURGE BACKUP LOGS': purge-backup-logs. statement removes
rows from the MySQL Backup log tables in the `mysql' database,
`backup_history' and `backup_progress' (see *Note
backup-database-restore-monitoring::). This statement requires the
`SUPER' privilege.

With no `TO' or `BEFORE' clause, the statement deletes all rows in the
log tables. With a `TO' clause, the statement deletes rows with a
`backup_id' column value less than the ID value. With a `BEFORE'
clause, the statement deletes rows with a `start_time' column value
less than the DATETIME_EXPR value. The DATETIME_EXPR argument should
evaluate to a *Note `DATETIME': datetime. value (a value in
`'YYYY-MM-DD hh:mm:ss'' format).

Examples:

     PURGE BACKUP LOGS TO 143;
     PURGE BACKUP LOGS BEFORE '2008-10-31 14:32:19';

*Note `PURGE BACKUP LOGS': purge-backup-logs. was added in MySQL 6.0.9.


File: manual.info,  Node: restore,  Prev: purge-backup-logs,  Up: backup-restore-sql

12.5.3.3 `RESTORE' Syntax
.........................

     RESTORE FROM 'IMAGE_FILE_NAME'
         [OPTION] ...

     OPTION = {OVERWRITE | SKIP_GAP_EVENT}

Given a backup image file created by the *Note `BACKUP DATABASE':
backup-database. statement, *Note `RESTORE': restore. restores the
databases contained in the image. The image file must be named as a
literal string. Its location must be in a directory where the server
can read files. If the `secure_file_priv' system variable is set to a
non-empty directory name, the image file must be located in that
directory. (Before MySQL 6.0.11, `secure_file_priv' applies instead.)

As of MySQL 6.0.7, the `backupdir' system variable value is the default
image file directory for *Note `RESTORE': restore. operations. If an
image file is named as a relative path name, it is interpreted relative
to the value of `backupdir'. The default value is the data directory.
Before MySQL 6.0.7, the file should be specified as a full path name.

*Note `RESTORE': restore. requires the `SUPER' privilege.

The *Note `RESTORE': restore. statement takes no database names
specifying which databases to restore. It restores the entire contents
of the image file. The databases are restored to their state at the
time that the image file was created. Restoring the image file can be
combined with use of the binary log to achieve point-in-time recovery
(see *Note point-in-time-recovery::).

Upon successful completion, the *Note `RESTORE': restore. statement
returns a result set with the backup number. Warnings produced during
the operation can be displayed with *Note `SHOW WARNINGS':
show-warnings. If the restore operation fails, it returns an error.

     mysql> RESTORE FROM '/tmp/world.backup';
     +-----------+
     | backup_id |
     +-----------+
     | 9         |
     +-----------+

While the operation is in progress, it can be monitored as described in
*Note backup-database-restore-monitoring::.

*Note `RESTORE': restore. detects whether the image file is compressed
and uncompresses it automatically as necessary. (Compressed image files
can be produced by using the `WITH COMPRESSION' clause in the *Note
`BACKUP DATABASE': backup-database. statement.)

As of MySQL 6.0.9, *Note `RESTORE': restore. aborts with an error if
the backup image contains any databases that currently exist on the
server, unless the optional keyword `OVERWRITE' is given following the
image file name. With `OVERWRITE', *Note `RESTORE': restore. is a
destructive operation. Each restored database is first dropped and then
created and populated with the tables contained in the backup image.
There is no warning about existing data being overwritten.

*Caution*:

The `OVERWRITE' is not available before MySQL 6.0.9 and *Note
`RESTORE': restore. is always a destructive operation.

The `SKIP_GAP_EVENT' can be useful when executing a *Note `RESTORE':
restore. statement on a replication master. Normally, when a restore
operation executes on a master, a gap event is written to the binary log
to signal all slaves to stop replication. This is a protective measure
to ensure that whatever changes the restore makes on the master do not
break replication.

The normal process is for the user to assess the effect of the restore
and, if appropriate, to apply the restore on the slaves as well prior
to restarting replication. However, it is possible that the slaves are
not replicating the databases in the backup image. In this case, the
restore operation would have no affect on the slave. Under these
conditions, the slaves need not be stopped and the restore is safe to
execute without disrupting replication. The `SKIP_GAP_EVENT' option
accomplishes this because it causes the gap event not to be written to
the binary log. This option is available as of MySQL 6.0.11.

During a *Note `RESTORE': restore. operation, foreign key constraints
are disabled so that the operation can create and populate tables
without causing warnings or errors related to foreign keys.

The *Note `RESTORE': restore. statement is not written to the binary
log and does not replicate to slave servers.

For general information about *Note `BACKUP DATABASE': backup-database.
and *Note `RESTORE': restore, see *Note backup-database-restore::.
Limitations on the use of these statements are discussed in *Note
backup-database-restore-restrictions::.

*Note `RESTORE': restore. was added in MySQL 6.0.5.


File: manual.info,  Node: plugin-sql,  Next: set-option,  Prev: backup-restore-sql,  Up: sql-syntax-server-administration

12.5.4 Plugin and User-Defined Function Statements
--------------------------------------------------

* Menu:

* create-function-udf::          `CREATE FUNCTION' Syntax
* drop-function-udf::            `DROP FUNCTION' Syntax
* install-plugin::               `INSTALL PLUGIN' Syntax
* uninstall-plugin::             `UNINSTALL PLUGIN' Syntax


File: manual.info,  Node: create-function-udf,  Next: drop-function-udf,  Prev: plugin-sql,  Up: plugin-sql

12.5.4.1 `CREATE FUNCTION' Syntax
.................................

     CREATE [AGGREGATE] FUNCTION FUNCTION_NAME RETURNS {STRING|INTEGER|REAL|DECIMAL}
         SONAME SHARED_LIBRARY_NAME

A user-defined function (UDF) is a way to extend MySQL with a new
function that works like a native (built-in) MySQL function such as
`ABS()' or `CONCAT()'.

FUNCTION_NAME is the name that should be used in SQL statements to
invoke the function. The `RETURNS' clause indicates the type of the
function's return value. *Note `DECIMAL': numeric-types.  is a legal
value after `RETURNS', but currently *Note `DECIMAL': numeric-types.
functions return string values and should be written like `STRING'
functions.

SHARED_LIBRARY_NAME is the basename of the shared object file that
contains the code that implements the function. The file must be
located in the plugin directory.  This directory is given by the value
of the `plugin_dir' system variable.

To create a function, you must have the `INSERT' privilege for the
`mysql' database. This is necessary because *Note `CREATE FUNCTION':
create-function. adds a row to the `mysql.func' system table that
records the function's name, type, and shared library name. If you do
not have this table, you should run the *Note `mysql_upgrade':
mysql-upgrade. command to create it. See *Note mysql-upgrade::.

An active function is one that has been loaded with *Note `CREATE
FUNCTION': create-function. and not removed with *Note `DROP FUNCTION':
drop-function. All active functions are reloaded each time the server
starts, unless you start *Note `mysqld': mysqld. with the
`--skip-grant-tables' option. In this case, UDF initialization is
skipped and UDFs are unavailable.

For instructions on writing user-defined functions, see *Note
adding-udf::. For the UDF mechanism to work, functions must be written
in C or C++ (or another language that can use C calling conventions),
your operating system must support dynamic loading and you must have
compiled *Note `mysqld': mysqld. dynamically (not statically).

An `AGGREGATE' function works exactly like a native MySQL aggregate
(summary) function such as `SUM' or `COUNT()'. For `AGGREGATE' to work,
your `mysql.func' table must contain a `type' column. If your
`mysql.func' table does not have this column, you should run the *Note
`mysql_upgrade': mysql-upgrade. program to create it (see *Note
mysql-upgrade::).

*Note*:

To upgrade the shared library associated with a UDF, issue a *Note
`DROP FUNCTION': drop-function. statement, upgrade the shared library,
and then issue a *Note `CREATE FUNCTION': create-function. statement. If
you upgrade the shared library first and then use *Note `DROP
FUNCTION': drop-function, the server may crash.


File: manual.info,  Node: drop-function-udf,  Next: install-plugin,  Prev: create-function-udf,  Up: plugin-sql

12.5.4.2 `DROP FUNCTION' Syntax
...............................

     DROP FUNCTION FUNCTION_NAME

This statement drops the user-defined function (UDF) named
FUNCTION_NAME.

To drop a function, you must have the `DELETE' privilege for the
`mysql' database. This is because *Note `DROP FUNCTION': drop-function.
removes a row from the `mysql.func' system table that records the
function's name, type, and shared library name.

*Note*:

To upgrade the shared library associated with a UDF, issue a *Note
`DROP FUNCTION': drop-function. statement, upgrade the shared library,
and then issue a *Note `CREATE FUNCTION': create-function. statement. If
you upgrade the shared library first and then use *Note `DROP
FUNCTION': drop-function, the server may crash.

*Note `DROP FUNCTION': drop-function. is also used to drop stored
functions (see *Note drop-procedure::).


File: manual.info,  Node: install-plugin,  Next: uninstall-plugin,  Prev: drop-function-udf,  Up: plugin-sql

12.5.4.3 `INSTALL PLUGIN' Syntax
................................

     INSTALL PLUGIN PLUGIN_NAME SONAME 'PLUGIN_LIBRARY'

This statement installs a plugin.

PLUGIN_NAME is the name of the plugin as defined in the plugin
declaration structure contained in the library file. Plugin names are
not case sensitive. For maximal compatibility, plugin names should be
limited to ASCII letters, digits, and underscore, because they are used
in C source files, shell command lines, M4 and Bourne shell scripts,
and SQL environments.

PLUGIN_LIBRARY is the name of the shared library that contains the
plugin code. The name includes the file name extension (for example,
`libmyplugin.so' or `libmyplugin.dylib').

The shared library must be located in the plugin directory (that is,
the directory named by the `plugin_dir' system variable).  The library
must be in the plugin directory itself, not in a subdirectory. By
default, `plugin_dir' is `plugin' directory under the directory named
by the `pkglibdir' configuration variable, but it can be changed by
setting the value of `plugin_dir' at server startup.  For example, set
its value in a `my.cnf' file:

     [mysqld]
     plugin_dir=/PATH/TO/PLUGIN/DIRECTORY

If the value of `plugin_dir' is a relative path name, it is taken to be
relative to the MySQL base directory (the value of the `basedir' system
variable).

*Note `INSTALL PLUGIN': install-plugin. adds a line to the
`mysql.plugin' table that describes the `plugin'. This table contains
the plugin name and library file name.

*Note `INSTALL PLUGIN': install-plugin. also loads and initializes the
plugin code to make the plugin available for use. A plugin is
initialized by executing its initialization function, which handles any
setup that the plugin must perform before it can be used.

To use *Note `INSTALL PLUGIN': install-plugin, you must have the
`INSERT privilege' for the `mysql.plugin' table.

At server startup, the server loads and initializes any plugin that is
listed in the `mysql.plugin' table.  This means that a plugin is
installed with *Note `INSTALL PLUGIN': install-plugin. only once, not
every time the server starts. Plugin loading at startup does not occur
if the server is started with the `--skip-grant-tables' option.

When the server shuts down, it executes the deinitialization function
for each plugin that is loaded so that the plugin has a change to
perform any final cleanup.

If you need to load plugins for a single server startup when the
`--skip-grant-tables' option is given (which tells the server not to
read system tables), use the `--plugin-load' option. See *Note
server-options::.

To remove a plugin entirely, use the *Note `UNINSTALL PLUGIN':
uninstall-plugin. statement:

To see what plugins are installed, use the `SHOW PLUGIN' statement.

If you recompile a plugin library and need to reinstall it, you can use
either of the following procedures:

   * Use *Note `UNINSTALL PLUGIN': uninstall-plugin. to uninstall all
     plugins in the library, install the new plugin library file in the
     plugin directory, and then use *Note `INSTALL PLUGIN':
     install-plugin. to install all plugins in the library. This
     procedure has the advantage that it can be used without stopping
     the server. However, if the plugin library contains many plugins,
     you must issue many *Note `INSTALL PLUGIN': install-plugin. and
     *Note `UNINSTALL PLUGIN': uninstall-plugin. statements.

   * Alternatively, stop the server, install the new plugin library
     file in the plugin directory, and then restart the server.


File: manual.info,  Node: uninstall-plugin,  Prev: install-plugin,  Up: plugin-sql

12.5.4.4 `UNINSTALL PLUGIN' Syntax
..................................

     UNINSTALL PLUGIN PLUGIN_NAME

This statement removes an installed plugin. You cannot uninstall a
plugin if any table that uses it is open.

PLUGIN_NAME must be the name of some plugin that is listed in the
`mysql.plugin' table. The server executes the plugin's deinitialization
function and removes the row for the plugin from the `mysql.plugin'
table, so that subsequent server restarts will not load and initialize
the plugin.  *Note `UNINSTALL PLUGIN': uninstall-plugin. does not remove
the plugin's shared library file.

To use *Note `UNINSTALL PLUGIN': uninstall-plugin, you must have the
`DELETE' privilege for the `mysql.plugin' table.

Plugin removal has implications for the use of associated tables. For
example, if a full-text parser plugin is associated with a `FULLTEXT'
index on the table, uninstalling the plugin makes the table unusable.
Any attempt to access the table results in an error. The table cannot
even be opened, so you cannot drop an index for which the plugin is
used. This means that uninstalling a plugin is something to do with
care unless you do not care about the table contents. If you are
uninstalling a plugin with no intention of reinstalling it later and
you care about the table contents, you should dump the table with *Note
`mysqldump': mysqldump. and remove the `WITH PARSER' clause from the
dumped *Note `CREATE TABLE': create-table. statement so that you can
reload the table later. If you do not care about the table, *Note `DROP
TABLE': drop-table. can be used even if any plugins associated with the
table are missing.


File: manual.info,  Node: set-option,  Next: show,  Prev: plugin-sql,  Up: sql-syntax-server-administration

12.5.5 `SET' Syntax
-------------------

     SET VARIABLE_ASSIGNMENT [, VARIABLE_ASSIGNMENT] ...

     VARIABLE_ASSIGNMENT:
           USER_VAR_NAME = EXPR
         | [GLOBAL | SESSION] SYSTEM_VAR_NAME = EXPR
         | [@@global. | @@session. | @@]SYSTEM_VAR_NAME = EXPR

The *Note `SET': set-option.  statement assigns values to different
types of variables that affect the operation of the server or your
client. Older versions of MySQL employed `SET OPTION', but this syntax
is deprecated in favor of *Note `SET': set-option. without `OPTION'.

This section describes use of *Note `SET': set-option. for assigning
values to system variables or user variables. For general information
about these types of variables, see *Note server-system-variables::,
*Note server-session-variables::, and *Note user-variables::. System
variables also can be set at server startup, as described in *Note
using-system-variables::.

Some variants of *Note `SET': set-option. syntax are used in other
contexts:

   * `SET CHARACTER SET' and `SET NAMES' assign values to character set
     and collation variables associated with the connection to the
     server.  `SET ONESHOT' is used for replication. These variants are
     described later in this section.

   * *Note `SET PASSWORD': set-password. assigns account passwords. See
     *Note set-password::.

   * *Note `SET TRANSACTION ISOLATION LEVEL': set-transaction. sets the
     isolation level for transaction processing. See *Note
     set-transaction::.

   * `SET' is used within stored routines to assign values to local
     routine variables. See *Note set-statement::.

The following discussion shows the different *Note `SET': set-option.
syntaxes that you can use to set variables. The examples use the `='
assignment operator, but the `:=' operator also is allowable.

A user variable is written as `@VAR_NAME' and can be set as follows:

     SET @VAR_NAME = EXPR;

Many system variables are dynamic and can be changed while the server
runs by using the *Note `SET': set-option.  statement. For a list, see
*Note dynamic-system-variables::. To change a system variable with
*Note `SET': set-option, refer to it as VAR_NAME, optionally preceded
by a modifier:

   * To indicate explicitly that a variable is a global variable,
     precede its name by `GLOBAL' or `@@global.'. The `SUPER' privilege
     is required to set global variables.

   * To indicate explicitly that a variable is a session variable,
     precede its name by `SESSION', `@@session.', or `@@'.  Setting a
     session variable requires no special privilege, but a client can
     change only its own session variables, not those of any other
     client.

   * `LOCAL' and `@@local.' are synonyms for `SESSION' and `@@session.'.

   * If no modifier is present, *Note `SET': set-option.  changes the
     session variable.

MySQL Enterprise

The MySQL Enterprise Monitor makes extensive use of system variables to
determine the state of your server. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

A *Note `SET': set-option.  statement can contain multiple variable
assignments, separated by commas. If you set several system variables,
the most recent `GLOBAL' or `SESSION' modifier in the statement is used
for following variables that have no modifier specified.

Examples:

     SET sort_buffer_size=10000;
     SET @@local.sort_buffer_size=10000;
     SET GLOBAL sort_buffer_size=1000000, SESSION sort_buffer_size=1000000;
     SET @@sort_buffer_size=1000000;
     SET @@global.sort_buffer_size=1000000, @@local.sort_buffer_size=1000000;

The `@@VAR_NAME' syntax for system variables is supported for
compatibility with some other database systems.

If you change a session system variable, the value remains in effect
until your session ends or until you change the variable to a different
value. The change is not visible to other clients.

If you change a global system variable, the value is remembered and
used for new connections until the server restarts. (To make a global
system variable setting permanent, you should set it in an option
file.) The change is visible to any client that accesses that global
variable. However, the change affects the corresponding session
variable only for clients that connect after the change. The global
variable change does not affect the session variable for any client
that is currently connected (not even that of the client that issues the
*Note `SET GLOBAL': set-option.  statement).

To prevent incorrect usage, MySQL produces an error if you use *Note
`SET GLOBAL': set-option.  with a variable that can only be used with
*Note `SET SESSION': set-option.  or if you do not specify `GLOBAL' (or
`@@global.') when setting a global variable.

To set a `SESSION' variable to the `GLOBAL' value or a `GLOBAL' value
to the compiled-in MySQL default value, use the `DEFAULT' keyword. For
example, the following two statements are identical in setting the
session value of `max_join_size' to the global value:

     SET max_join_size=DEFAULT;
     SET @@session.max_join_size=@@global.max_join_size;

Not all system variables can be set to `DEFAULT'.  In such cases, use
of `DEFAULT' results in an error.

You can refer to the values of specific global or sesson system
variables in expressions by using one of the `@@'-modifiers. For
example, you can retrieve values in a *Note `SELECT': select. statement
like this:

     SELECT @@global.sql_mode, @@session.sql_mode, @@sql_mode;

When you refer to a system variable in an expression as `@@VAR_NAME'
(that is, when you do not specify `@@global.' or `@@session.'), MySQL
returns the session value if it exists and the global value otherwise.
(This differs from `SET @@VAR_NAME = VALUE', which always refers to the
session value.)

*Note*:

Some variables displayed by `SHOW VARIABLES' may not not be available
using `SELECT @@VAR_NAME' syntax; an `Unknown system variable' occurs.
As a workaround in such cases, you can use `SHOW VARIABLES LIKE
'VAR_NAME''.

Suffixes for specifying a value multiplier can be used when setting a
variable at server startup, but not to set the value with *Note `SET':
set-option. at runtime. On the other hand, with *Note `SET':
set-option. you can assign a variable's value using an expression,
which is not true when you set a variable at server startup. For
example, the first of the following lines is legal at server startup,
but the second is not:

     shell> mysql --max_allowed_packet=16M
     shell> mysql --max_allowed_packet=16*1024*1024

Conversely, the second of the following lines is legal at runtime, but
the first is not:

     mysql> SET GLOBAL max_allowed_packet=16M;
     mysql> SET GLOBAL max_allowed_packet=16*1024*1024;

To display system variables names and values, use the *Note `SHOW
VARIABLES': show-variables. statement. (See *Note show-variables::.)

The following list describes *Note `SET': set-option. options that have
non-standard syntax (that is, options that are not set with `NAME =
VALUE' syntax).

   * `CHARACTER SET {CHARSET_NAME | DEFAULT}'

     This maps all strings from and to the client with the given
     mapping. You can add new mappings by editing `sql/convert.cc' in
     the MySQL source distribution. `SET CHARACTER SET' sets three
     session system variables: `character_set_client' and
     `character_set_results' are set to the given character set, and
     `character_set_connection' to the value of
     `character_set_database'. See *Note charset-connection::.

     The default mapping can be restored by using the value `DEFAULT'.
     The default depends on the server configuration.

     `ucs2', `utf16', and `utf32' cannot be used as a client character
     set, which means that they do not work for `SET CHARACTER SET'.

   * `NAMES {'CHARSET_NAME' [COLLATE 'COLLATION_NAME'] | DEFAULT}'

     `SET NAMES' sets the three session system variables
     `character_set_client', `character_set_connection', and
     `character_set_results' to the given character set. Setting
     `character_set_connection' to `charset_name' also sets
     `collation_connection' to the default collation for
     `charset_name'. The optional `COLLATE' clause may be used to
     specify a collation explicitly. See *Note charset-connection::.

     The default mapping can be restored by using a value of `DEFAULT'.
     The default depends on the server configuration.

     `ucs2', `utf16', and `utf32' cannot be used as a client character
     set, which means that they do not work for `SET NAMES'.

   * `ONE_SHOT'

     This option is a modifier, not a variable. It can be used to
     influence the effect of variables that set the character set, the
     collation, and the time zone. `ONE_SHOT' is primarily used for
     replication purposes: *Note `mysqlbinlog': mysqlbinlog. uses `SET
     ONE_SHOT' to modify temporarily the values of character set,
     collation, and time zone variables to reflect at rollforward what
     they were originally.  `ONE_SHOT' is for internal use only and is
     deprecated for MySQL 5.0 and up.

     You cannot use `ONE_SHOT' with other than the allowed set of
     variables; if you try, you get an error like this:

          mysql> SET ONE_SHOT max_allowed_packet = 1;
          ERROR 1382 (HY000): The 'SET ONE_SHOT' syntax is reserved for purposes
          internal to the MySQL server

     If `ONE_SHOT' is used with the allowed variables, it changes the
     variables as requested, but only for the next non-*Note `SET':
     set-option.  statement. After that, the server resets all
     character set, collation, and time zone-related system variables
     to their previous values. Example:

          mysql> SET ONE_SHOT character_set_connection = latin5;

          mysql> SET ONE_SHOT collation_connection = latin5_turkish_ci;

          mysql> SHOW VARIABLES LIKE '%_connection';
          +--------------------------+-------------------+
          | Variable_name            | Value             |
          +--------------------------+-------------------+
          | character_set_connection | latin5            |
          | collation_connection     | latin5_turkish_ci |
          +--------------------------+-------------------+

          mysql> SHOW VARIABLES LIKE '%_connection';
          +--------------------------+-------------------+
          | Variable_name            | Value             |
          +--------------------------+-------------------+
          | character_set_connection | latin1            |
          | collation_connection     | latin1_swedish_ci |
          +--------------------------+-------------------+


File: manual.info,  Node: show,  Next: other-administrative-sql,  Prev: set-option,  Up: sql-syntax-server-administration

12.5.6 `SHOW' Syntax
--------------------

* Menu:

* show-authors::                 `SHOW AUTHORS' Syntax
* show-binary-logs::             `SHOW BINARY LOGS' Syntax
* show-binlog-events::           `SHOW BINLOG EVENTS' Syntax
* show-character-set::           `SHOW CHARACTER SET' Syntax
* show-collation::               `SHOW COLLATION' Syntax
* show-columns::                 `SHOW COLUMNS' Syntax
* show-contributors::            `SHOW CONTRIBUTORS' Syntax
* show-create-database::         `SHOW CREATE DATABASE' Syntax
* show-create-event::            `SHOW CREATE EVENT' Syntax
* show-create-function::         `SHOW CREATE FUNCTION' Syntax
* show-create-procedure::        `SHOW CREATE PROCEDURE' Syntax
* show-create-table::            `SHOW CREATE TABLE' Syntax
* show-create-trigger::          `SHOW CREATE TRIGGER' Syntax
* show-create-view::             `SHOW CREATE VIEW' Syntax
* show-databases::               `SHOW DATABASES' Syntax
* show-engine::                  `SHOW ENGINE' Syntax
* show-engines::                 `SHOW ENGINES' Syntax
* show-errors::                  `SHOW ERRORS' Syntax
* show-events::                  `SHOW EVENTS' Syntax
* show-function-code::           `SHOW FUNCTION CODE' Syntax
* show-function-status::         `SHOW FUNCTION STATUS' Syntax
* show-grants::                  `SHOW GRANTS' Syntax
* show-index::                   `SHOW INDEX' Syntax
* show-master-status::           `SHOW MASTER STATUS' Syntax
* show-open-tables::             `SHOW OPEN TABLES' Syntax
* show-plugins::                 `SHOW PLUGINS' Syntax
* show-privileges::              `SHOW PRIVILEGES' Syntax
* show-procedure-code::          `SHOW PROCEDURE CODE' Syntax
* show-procedure-status::        `SHOW PROCEDURE STATUS' Syntax
* show-processlist::             `SHOW PROCESSLIST' Syntax
* show-profile::                 `SHOW PROFILE' Syntax
* show-profiles::                `SHOW PROFILES' Syntax
* show-slave-hosts::             `SHOW SLAVE HOSTS' Syntax
* show-slave-status::            `SHOW SLAVE STATUS' Syntax
* show-status::                  `SHOW STATUS' Syntax
* show-table-status::            `SHOW TABLE STATUS' Syntax
* show-tables::                  `SHOW TABLES' Syntax
* show-triggers::                `SHOW TRIGGERS' Syntax
* show-variables::               `SHOW VARIABLES' Syntax
* show-warnings::                `SHOW WARNINGS' Syntax

*Note `SHOW': show. has many forms that provide information about
databases, tables, columns, or status information about the server.
This section describes those following:

     SHOW AUTHORS
     SHOW CHARACTER SET [LIKE_OR_WHERE]
     SHOW COLLATION [LIKE_OR_WHERE]
     SHOW [FULL] COLUMNS FROM TBL_NAME [FROM DB_NAME] [LIKE_OR_WHERE]
     SHOW CONTRIBUTORS
     SHOW CREATE DATABASE DB_NAME
     SHOW CREATE EVENT EVENT_NAME
     SHOW CREATE FUNCTION FUNC_NAME
     SHOW CREATE PROCEDURE PROC_NAME
     SHOW CREATE TABLE TBL_NAME
     SHOW CREATE TRIGGER TRIGGER_NAME
     SHOW CREATE VIEW VIEW_NAME
     SHOW DATABASES [LIKE_OR_WHERE]
     SHOW ENGINE ENGINE_NAME {STATUS | MUTEX}
     SHOW [STORAGE] ENGINES
     SHOW ERRORS [LIMIT [OFFSET,] ROW_COUNT]
     SHOW [FULL] EVENTS
     SHOW FUNCTION CODE FUNC_NAME
     SHOW FUNCTION STATUS [LIKE_OR_WHERE]
     SHOW GRANTS FOR USER
     SHOW INDEX FROM TBL_NAME [FROM DB_NAME]
     SHOW OPEN TABLES [FROM DB_NAME] [LIKE_OR_WHERE]
     SHOW PLUGINS
     SHOW PROCEDURE CODE PROC_NAME
     SHOW PROCEDURE STATUS [LIKE_OR_WHERE]
     SHOW PRIVILEGES
     SHOW [FULL] PROCESSLIST
     SHOW PROFILE [TYPES] [FOR QUERY N] [OFFSET N] [LIMIT N]
     SHOW PROFILES
     SHOW SCHEDULER STATUS
     SHOW [GLOBAL | SESSION] STATUS [LIKE_OR_WHERE]
     SHOW TABLE STATUS [FROM DB_NAME] [LIKE_OR_WHERE]
     SHOW TABLES [FROM DB_NAME] [LIKE_OR_WHERE]
     SHOW TRIGGERS [FROM DB_NAME] [LIKE_OR_WHERE]
     SHOW [GLOBAL | SESSION] VARIABLES [LIKE_OR_WHERE]
     SHOW WARNINGS [LIMIT [OFFSET,] ROW_COUNT]

     LIKE_OR_WHERE:
         LIKE 'PATTERN'
       | WHERE EXPR

If the syntax for a given *Note `SHOW': show.  statement includes a
`LIKE 'PATTERN'' part, `'PATTERN'' is a string that can contain the SQL
``%'' and ``_'' wildcard characters. The pattern is useful for
restricting statement output to matching values.

Several *Note `SHOW': show. statements also accept a `WHERE' clause
that provides more flexibility in specifying which rows to display. See
*Note extended-show::.

Many MySQL APIs (such as PHP) allow you to treat the result returned
from a *Note `SHOW': show. statement as you would a result set from a
*Note `SELECT': select.; see *Note connectors-apis::, or your API
documentation for more information. In addition, you can work in SQL
with results from queries on tables in the `INFORMATION_SCHEMA'
database, which you cannot easily do with results from *Note `SHOW':
show.  statements. See *Note information-schema::.


File: manual.info,  Node: show-authors,  Next: show-binary-logs,  Prev: show,  Up: show

12.5.6.1 `SHOW AUTHORS' Syntax
..............................

     SHOW AUTHORS

The *Note `SHOW AUTHORS': show-authors. statement displays information
about the people who work on MySQL. For each author, it displays `Name',
`Location', and `Comment' values.


File: manual.info,  Node: show-binary-logs,  Next: show-binlog-events,  Prev: show-authors,  Up: show

12.5.6.2 `SHOW BINARY LOGS' Syntax
..................................

     SHOW BINARY LOGS
     SHOW MASTER LOGS

Lists the binary log files on the server. This statement is used as
part of the procedure described in *Note purge-binary-logs::, that
shows how to determine which logs can be purged.

     mysql> SHOW BINARY LOGS;
     +---------------+-----------+
     | Log_name      | File_size |
     +---------------+-----------+
     | binlog.000015 |    724935 |
     | binlog.000016 |    733481 |
     +---------------+-----------+

*Note `SHOW MASTER LOGS': show-binary-logs. is equivalent to *Note
`SHOW BINARY LOGS': show-binary-logs.


File: manual.info,  Node: show-binlog-events,  Next: show-character-set,  Prev: show-binary-logs,  Up: show

12.5.6.3 `SHOW BINLOG EVENTS' Syntax
....................................

     SHOW BINLOG EVENTS
        [IN 'LOG_NAME'] [FROM POS] [LIMIT [OFFSET,] ROW_COUNT]

Shows the events in the binary log. If you do not specify `'LOG_NAME'',
the first binary log is displayed.

The `LIMIT' clause has the same syntax as for the *Note `SELECT':
select. statement. See *Note select::.

*Note*:

Issuing a *Note `SHOW BINLOG EVENTS': show-binlog-events.  with no
`LIMIT' clause could start a very time- and resource-consuming process
because the server returns to the client the complete contents of the
binary log (which includes all statements executed by the server that
modify data). As an alternative to *Note `SHOW BINLOG EVENTS':
show-binlog-events, use the *Note `mysqlbinlog': mysqlbinlog. utility
to save the binary log to a text file for later examination and
analysis. See *Note mysqlbinlog::.

*Note*:

Events relating to the setting of variables are not included in the
output from *Note `SHOW BINLOG EVENTS': show-binlog-events. To get
complete coverage of events within a binary log, use *Note
`mysqlbinlog': mysqlbinlog.


File: manual.info,  Node: show-character-set,  Next: show-collation,  Prev: show-binlog-events,  Up: show

12.5.6.4 `SHOW CHARACTER SET' Syntax
....................................

     SHOW CHARACTER SET
         [LIKE 'PATTERN' | WHERE EXPR]

The *Note `SHOW CHARACTER SET': show-character-set. statement shows all
available character sets. The `LIKE' clause, if present, indicates
which character set names to match. The `WHERE' clause can be given to
select rows using more general conditions, as discussed in *Note
extended-show::. For example:

     mysql> SHOW CHARACTER SET LIKE 'latin%';
     +---------+-----------------------------+-------------------+--------+
     | Charset | Description                 | Default collation | Maxlen |
     +---------+-----------------------------+-------------------+--------+
     | latin1  | cp1252 West European        | latin1_swedish_ci |      1 |
     | latin2  | ISO 8859-2 Central European | latin2_general_ci |      1 |
     | latin5  | ISO 8859-9 Turkish          | latin5_turkish_ci |      1 |
     | latin7  | ISO 8859-13 Baltic          | latin7_general_ci |      1 |
     +---------+-----------------------------+-------------------+--------+

The `Maxlen' column shows the maximum number of bytes required to store
one character.


File: manual.info,  Node: show-collation,  Next: show-columns,  Prev: show-character-set,  Up: show

12.5.6.5 `SHOW COLLATION' Syntax
................................

     SHOW COLLATION
         [LIKE 'PATTERN' | WHERE EXPR]

The output from *Note `SHOW COLLATION': show-collation.  includes all
available character sets. The `LIKE' clause, if present, indicates
which collation names to match. The `WHERE' clause can be given to
select rows using more general conditions, as discussed in *Note
extended-show::. For example:

     mysql> SHOW COLLATION LIKE 'latin1%';
     +-------------------+---------+----+---------+----------+---------+
     | Collation         | Charset | Id | Default | Compiled | Sortlen |
     +-------------------+---------+----+---------+----------+---------+
     | latin1_german1_ci | latin1  |  5 |         |          |       0 |
     | latin1_swedish_ci | latin1  |  8 | Yes     | Yes      |       0 |
     | latin1_danish_ci  | latin1  | 15 |         |          |       0 |
     | latin1_german2_ci | latin1  | 31 |         | Yes      |       2 |
     | latin1_bin        | latin1  | 47 |         | Yes      |       0 |
     | latin1_general_ci | latin1  | 48 |         |          |       0 |
     | latin1_general_cs | latin1  | 49 |         |          |       0 |
     | latin1_spanish_ci | latin1  | 94 |         |          |       0 |
     +-------------------+---------+----+---------+----------+---------+

The `Default' column indicates whether a collation is the default for
its character set.  `Compiled' indicates whether the character set is
compiled into the server. `Sortlen' is related to the amount of memory
required to sort strings expressed in the character set.

To see the default collation for each character set, use the following
statement. `Default' is a reserved word, so to use it as an identifier,
it must be quoted as such:

     mysql> SHOW COLLATION WHERE `Default` = 'Yes';
     +---------------------+----------+----+---------+----------+---------+
     | Collation           | Charset  | Id | Default | Compiled | Sortlen |
     +---------------------+----------+----+---------+----------+---------+
     | big5_chinese_ci     | big5     |  1 | Yes     | Yes      |       1 |
     | dec8_swedish_ci     | dec8     |  3 | Yes     | Yes      |       1 |
     | cp850_general_ci    | cp850    |  4 | Yes     | Yes      |       1 |
     | hp8_english_ci      | hp8      |  6 | Yes     | Yes      |       1 |
     | koi8r_general_ci    | koi8r    |  7 | Yes     | Yes      |       1 |
     | latin1_swedish_ci   | latin1   |  8 | Yes     | Yes      |       1 |
     ...


File: manual.info,  Node: show-columns,  Next: show-contributors,  Prev: show-collation,  Up: show

12.5.6.6 `SHOW COLUMNS' Syntax
..............................

     SHOW [FULL] COLUMNS {FROM | IN} TBL_NAME [{FROM | IN} DB_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

*Note `SHOW COLUMNS': show-columns. displays information about the
columns in a given table. It also works for views. The `LIKE' clause,
if present, indicates which column names to match. The `WHERE' clause
can be given to select rows using more general conditions, as discussed
in *Note extended-show::.

*Note `SHOW COLUMNS': show-columns. displays information only for those
columns that you have some privilege for.

     mysql> SHOW COLUMNS FROM City;
     +------------+----------+------+-----+---------+----------------+
     | Field      | Type     | Null | Key | Default | Extra          |
     +------------+----------+------+-----+---------+----------------+
     | Id         | int(11)  | NO   | PRI | NULL    | auto_increment |
     | Name       | char(35) | NO   |     |         |                |
     | Country    | char(3)  | NO   | UNI |         |                |
     | District   | char(20) | YES  | MUL |         |                |
     | Population | int(11)  | NO   |     | 0       |                |
     +------------+----------+------+-----+---------+----------------+
     5 rows in set (0.00 sec)

The `FULL' keyword causes the output to include the column collation
and comments, as well as the privileges you have for each column.

You can use DB_NAME.TBL_NAME as an alternative to the `TBL_NAME FROM
DB_NAME' syntax. In other words, these two statements are equivalent:

     mysql> SHOW COLUMNS FROM mytable FROM mydb;
     mysql> SHOW COLUMNS FROM mydb.mytable;

*Note `SHOW COLUMNS': show-columns. displays the following values for
each table column:

`Field' indicates the column name.

`Type' indicates the column data type.

`Collation' indicates the collation for non-binary string columns, or
`NULL' for other columns. This value is displayed only if you use the
`FULL' keyword.

The `Null' field contains `YES' if `NULL' values can be stored in the
column, `NO' if not.

The `Key' field indicates whether the column is indexed:

   * If `Key' is empty, the column either is not indexed or is indexed
     only as a secondary column in a multiple-column, non-unique index.

   * If `Key' is `PRI', the column is a `PRIMARY KEY' or is one of the
     columns in a multiple-column `PRIMARY KEY'.

   * If `Key' is `UNI', the column is the first column of a
     unique-valued index that cannot contain `NULL' values.

   * If `Key' is `MUL', multiple occurrences of a given value are
     allowed within the column. The column is the first column of a
     non-unique index or a unique-valued index that can contain `NULL'
     values.

If more than one of the `Key' values applies to a given column of a
table, `Key' displays the one with the highest priority, in the order
`PRI', `UNI', `MUL'.

A `UNIQUE' index may be displayed as `PRI' if it cannot contain `NULL'
values and there is no `PRIMARY KEY' in the table. A `UNIQUE' index may
display as `MUL' if several columns form a composite `UNIQUE' index;
although the combination of the columns is unique, each column can
still hold multiple occurrences of a given value.

The `Default' field indicates the default value that is assigned to the
column.

The `Extra' field contains any additional information that is available
about a given column. The value is `auto_increment' if the column was
created with the `AUTO_INCREMENT' keyword and empty otherwise.

`Privileges' indicates the privileges you have for the column. This
value is displayed only if you use the `FULL' keyword.

`Comment' indicates any comment the column has.  This value is
displayed only if you use the `FULL' keyword.

`SHOW FIELDS' is a synonym for *Note `SHOW COLUMNS': show-columns. You
can also list a table's columns with the *Note `mysqlshow DB_NAME
TBL_NAME': mysqlshow. command.

The *Note `DESCRIBE': describe. statement provides information similar
to *Note `SHOW COLUMNS': show-columns. See *Note describe::.

The *Note `SHOW CREATE TABLE': show-create-table, *Note `SHOW TABLE
STATUS': show-table-status, and *Note `SHOW INDEX': show-index.
statements also provide information about tables. See *Note show::.


File: manual.info,  Node: show-contributors,  Next: show-create-database,  Prev: show-columns,  Up: show

12.5.6.7 `SHOW CONTRIBUTORS' Syntax
...................................

     SHOW CONTRIBUTORS

The *Note `SHOW CONTRIBUTORS': show-contributors. statement displays
information about the people who contribute to MySQL source or to
causes that MySQL AB supports. For each contributor, it displays `Name',
`Location', and `Comment' values.


File: manual.info,  Node: show-create-database,  Next: show-create-event,  Prev: show-contributors,  Up: show

12.5.6.8 `SHOW CREATE DATABASE' Syntax
......................................

     SHOW CREATE {DATABASE | SCHEMA} DB_NAME

Shows the *Note `CREATE DATABASE': create-database.  statement that
creates the given database.  *Note `SHOW CREATE SCHEMA':
show-create-database. is a synonym for *Note `SHOW CREATE DATABASE':
show-create-database.

     mysql> SHOW CREATE DATABASE test\G
     *************************** 1. row ***************************
            Database: test
     Create Database: CREATE DATABASE `test`
                      /*!40100 DEFAULT CHARACTER SET latin1 */

     mysql> SHOW CREATE SCHEMA test\G
     *************************** 1. row ***************************
            Database: test
     Create Database: CREATE DATABASE `test`
                      /*!40100 DEFAULT CHARACTER SET latin1 */

*Note `SHOW CREATE DATABASE': show-create-database. quotes table and
column names according to the value of the `sql_quote_show_create'
option.  See *Note server-session-variables::.


File: manual.info,  Node: show-create-event,  Next: show-create-function,  Prev: show-create-database,  Up: show

12.5.6.9 `SHOW CREATE EVENT' Syntax
...................................

     SHOW CREATE EVENT EVENT_NAME

This statement displays the *Note `CREATE EVENT': create-event.
statement needed to re-create a given event. For example (using the
same event `e_daily' defined and then altered in *Note show-events::):

     mysql> SHOW CREATE EVENT test.e_daily\G
     *************************** 1. row ***************************
                    Event: e_daily
                 sql_mode:
                time_zone: SYSTEM
             Create Event: CREATE EVENT `e_daily`
                             ON SCHEDULE EVERY 1 DAY
                             STARTS CURRENT_TIMESTAMP + INTERVAL 6 HOUR
                             ON COMPLETION NOT PRESERVE
                             ENABLE
                             COMMENT 'Saves total number of sessions then
                                     clears the table each day'
                             DO BEGIN
                               INSERT INTO site_activity.totals (time, total)
                                 SELECT CURRENT_TIMESTAMP, COUNT(*)
                                 FROM site_activity.sessions;
                               DELETE FROM site_activity.sessions;
                             END
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

`character_set_client' is the session value of the
`character_set_client' system variable when the event was created.
`collation_connection' is the session value of the
`collation_connection' system variable when the event was created.
`Database Collation' is the collation of the database with which the
event is associated.

Note that the output reflects the current status of the event
(`ENABLE') rather than the status with which it was created.


File: manual.info,  Node: show-create-function,  Next: show-create-procedure,  Prev: show-create-event,  Up: show

12.5.6.10 `SHOW CREATE FUNCTION' Syntax
.......................................

     SHOW CREATE FUNCTION FUNC_NAME

This statement is similar to *Note `SHOW CREATE PROCEDURE':
show-create-procedure. but for stored functions. See *Note
show-create-procedure::.


File: manual.info,  Node: show-create-procedure,  Next: show-create-table,  Prev: show-create-function,  Up: show

12.5.6.11 `SHOW CREATE PROCEDURE' Syntax
........................................

     SHOW CREATE PROCEDURE PROC_NAME

This statement is a MySQL extension. It returns the exact string that
can be used to re-create the named stored procedure. A similar
statement, *Note `SHOW CREATE FUNCTION': show-create-function, displays
information about stored functions (see *Note show-create-function::).

Both statements require that you be the owner of the routine or have
*Note `SELECT': select. access to the `mysql.proc' table. If you do not
have privileges for the routine itself, the value displayed for the
`Create Procedure' or `Create Function' field will be `NULL'.

     mysql> SHOW CREATE PROCEDURE test.simpleproc\G
     *************************** 1. row ***************************
                Procedure: simpleproc
                 sql_mode:
         Create Procedure: CREATE PROCEDURE `simpleproc`(OUT param1 INT)
                           BEGIN
                           SELECT COUNT(*) INTO param1 FROM t;
                           END
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

     mysql> SHOW CREATE FUNCTION test.hello\G
     *************************** 1. row ***************************
                 Function: hello
                 sql_mode:
          Create Function: CREATE FUNCTION `hello`(s CHAR(20))
                           RETURNS CHAR(50)
                           RETURN CONCAT('Hello, ',s,'!')
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

`character_set_client' is the session value of the
`character_set_client' system variable when the routine was created.
`collation_connection' is the session value of the
`collation_connection' system variable when the routine was created.
`Database Collation' is the collation of the database with which the
routine is associated.


File: manual.info,  Node: show-create-table,  Next: show-create-trigger,  Prev: show-create-procedure,  Up: show

12.5.6.12 `SHOW CREATE TABLE' Syntax
....................................

     SHOW CREATE TABLE TBL_NAME

Shows the *Note `CREATE TABLE': create-table. statement that creates
the given table. To use the statement, it is sufficient to have any
privilege for the table as of MySQL 6.0.6. Previously, the statement
requires the `SELECT' privilege for the table.  This statement also
works with views.

     mysql> SHOW CREATE TABLE t\G
     *************************** 1. row ***************************
            Table: t
     Create Table: CREATE TABLE t (
       id INT(11) default NULL auto_increment,
       s char(60) default NULL,
       PRIMARY KEY (id)
     ) ENGINE=MyISAM

*Note `SHOW CREATE TABLE': show-create-table. quotes table and column
names according to the value of the `sql_quote_show_create' option.
See *Note server-session-variables::.


File: manual.info,  Node: show-create-trigger,  Next: show-create-view,  Prev: show-create-table,  Up: show

12.5.6.13 `SHOW CREATE TRIGGER' Syntax
......................................

     SHOW CREATE TRIGGER TRIGGER_NAME

This statement shows a *Note `CREATE TRIGGER': create-trigger.
statement that creates the given trigger.

     mysql> SHOW CREATE TRIGGER ins_sum\G
     *************************** 1. row ***************************
                    Trigger: ins_sum
                   sql_mode:
     SQL Original Statement: CREATE DEFINER=`bob`@`localhost` TRIGGER ins_sum
                             BEFORE INSERT ON account
                             FOR EACH ROW SET @sum = @sum + NEW.amount
       character_set_client: latin1
       collation_connection: latin1_swedish_ci
         Database Collation: latin1_swedish_ci

You can also obtain information about trigger objects from
`INFORMATION_SCHEMA', which contains a *Note `TRIGGERS':
triggers-table. table. See *Note triggers-table::.


File: manual.info,  Node: show-create-view,  Next: show-databases,  Prev: show-create-trigger,  Up: show

12.5.6.14 `SHOW CREATE VIEW' Syntax
...................................

     SHOW CREATE VIEW VIEW_NAME

This statement shows a *Note `CREATE VIEW': create-view. statement that
creates the given view.

     mysql> SHOW CREATE VIEW v\G
     *************************** 1. row ***************************
                     View: v
              Create View: CREATE ALGORITHM=UNDEFINED
                           DEFINER=`bob`@`localhost`
                           SQL SECURITY DEFINER VIEW
                           `v` AS select 1 AS `a`,2 AS `b`
     character_set_client: latin1
     collation_connection: latin1_swedish_ci

`character_set_client' is the session value of the
`character_set_client' system variable when the routine was created.
`collation_connection' is the session value of the
`collation_connection' system variable when the routine was created.

Use of *Note `SHOW CREATE VIEW': show-create-view. requires the `SHOW
VIEW' privilege and the `SELECT' privilege for the view in question.

You can also obtain information about view objects from
`INFORMATION_SCHEMA', which contains a *Note `VIEWS': views-table.
table. See *Note views-table::.

MySQL lets you use different `sql_mode' settings to tell the server the
type of SQL syntax to support. For example, you might use the `ANSI'
SQL mode to ensure MySQL correctly interprets the standard SQL
concatenation operator, the double bar (`||'), in your queries. If you
then create a view that concatenates items, you might worry that
changing the `sql_mode' setting to a value different from `ANSI' could
cause the view to become invalid. But this is not the case. No matter
how you write out a view definition, MySQL always stores it the same
way, in a canonical form. Here is an example that shows how the server
changes a double bar concatenation operator to a `CONCAT()' function:

     mysql> SET sql_mode = 'ANSI';
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE VIEW test.v AS SELECT 'a' || 'b' as col1;
     Query OK, 0 rows affected (0.01 sec)

     mysql> SHOW CREATE VIEW test.v\G
     *************************** 1. row ***************************
                     View: v
              Create View: CREATE VIEW "v" AS select concat('a','b') AS "col1"
     ...
     1 row in set (0.00 sec)

The advantage of storing a view definition in canonical form is that
changes made later to the value of `sql_mode' will not affect the
results from the view. However an additional consequence is that
comments prior to *Note `SELECT': select. are stripped from the
definition by the server.


File: manual.info,  Node: show-databases,  Next: show-engine,  Prev: show-create-view,  Up: show

12.5.6.15 `SHOW DATABASES' Syntax
.................................

     SHOW {DATABASES | SCHEMAS}
         [LIKE 'PATTERN' | WHERE EXPR]

*Note `SHOW DATABASES': show-databases. lists the databases on the
MySQL server host.  *Note `SHOW SCHEMAS': show-databases. is a synonym
for *Note `SHOW DATABASES': show-databases. The `LIKE' clause, if
present, indicates which database names to match. The `WHERE' clause
can be given to select rows using more general conditions, as discussed
in *Note extended-show::.

You see only those databases for which you have some kind of privilege,
unless you have the global *Note `SHOW DATABASES': show-databases.
privilege. You can also get this list using the *Note `mysqlshow':
mysqlshow. command.

If the server was started with the `--skip-show-database' option, you
cannot use this statement at all unless you have the `SHOW DATABASES'
privilege.

*Note `SHOW SCHEMAS': show-databases. can also be used.


File: manual.info,  Node: show-engine,  Next: show-engines,  Prev: show-databases,  Up: show

12.5.6.16 `SHOW ENGINE' Syntax
..............................

     SHOW ENGINE ENGINE_NAME {STATUS | MUTEX}

*Note `SHOW ENGINE': show-engine. displays operational information
about a storage engine. The following statements currently are
supported:

     SHOW ENGINE INNODB STATUS
     SHOW ENGINE INNODB MUTEX

*Note `SHOW ENGINE INNODB STATUS': show-engine. displays extensive
information from the standard `InnoDB' Monitor about the state of the
`InnoDB' storage engine. For information about the standard monitor and
other `InnoDB' Monitors that provide information about `InnoDB'
processing, see *Note innodb-monitors::.

*Note `SHOW ENGINE INNODB MUTEX': show-engine. displays `InnoDB' mutex
statistics. The statement displays the following fields:

   * `Type'

     Always `InnoDB'.

   * `Name'

     The source file where the mutex is implemented, and the line
     number in the file where the mutex is created. The line number may
     change depending on your version of MySQL.

   * `Status'

     The mutex status. This field displays several values if
     `UNIV_DEBUG' was defined at MySQL compilation time (for example, in
     `include/univ.h' in the `InnoDB' part of the MySQL source tree). If
     `UNIV_DEBUG' was not defined, the statement displays only the
     `os_waits' value. In the latter case (without UNIV_DEBUG), the
     information on which the output is based is insufficient to
     distinguish regular mutexes and mutexes that protect rw-locks
     (which allow multiple readers or a single writer). Consequently,
     the output may appear to contain multiple rows for the same mutex.

        * `count' indicates how many times the mutex was requested.

        * `spin_waits' indicates how many times the spinlock had to run.

        * `spin_rounds' indicates the number of spinlock rounds.
          (`spin_rounds' divided by `spin_waits' provides the average
          round count.)

        * `os_waits' indicates the number of operating system waits.
          This occurs when the spinlock did not work (the mutex was not
          locked during the spinlock and it was necessary to yield to
          the operating system and wait).

        * `os_yields' indicates the number of times a the thread trying
          to lock a mutex gave up its timeslice and yielded to the
          operating system (on the presumption that allowing other
          threads to run will free the mutex so that it can be locked).

        * `os_wait_times' indicates the amount of time (in ms) spent in
          operating system waits, if the `timed_mutexes' system
          variable is 1 (`ON'). If `timed_mutexes' is 0 (`OFF'), timing
          is disabled, so `os_wait_times' is 0.  `timed_mutexes' is off
          by default.

Information from this statement can be used to diagnose system
problems. For example, large values of `spin_waits' and `spin_rounds'
may indicate scalability problems.

MySQL Enterprise

The `SHOW ENGINE ENGINE_NAME STATUS' statement provides valuable
information about the state of your server. For expert interpretation
of this information, subscribe to the MySQL Enterprise Monitor. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: show-engines,  Next: show-errors,  Prev: show-engine,  Up: show

12.5.6.17 `SHOW ENGINES' Syntax
...............................

     SHOW [STORAGE] ENGINES

*Note `SHOW ENGINES': show-engines. displays status information about
the server's storage engines. This is particularly useful for checking
whether a storage engine is supported, or to see what the default
engine is.

     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 4
     Server version: 6.0.2-alpha-log Source distribution

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql>> show engines\G
     *************************** 1. row ***************************
           Engine: FEDERATED
          Support: YES
          Comment: Federated MySQL storage engine
     Transactions: YES
               XA: NO
       Savepoints: NO
     *************************** 2. row ***************************
           Engine: MRG_MYISAM
          Support: YES
          Comment: Collection of identical MyISAM tables
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 3. row ***************************
           Engine: CSV
          Support: YES
          Comment: CSV storage engine
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 4. row ***************************
           Engine: Falcon
          Support: YES
          Comment: Falcon storage engine
     Transactions: YES
               XA: NO
       Savepoints: YES
     *************************** 5. row ***************************
           Engine: BLACKHOLE
          Support: YES
          Comment: /dev/null storage engine (anything you write to it disappears)
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 6. row ***************************
           Engine: MEMORY
          Support: YES
          Comment: Hash based, stored in memory, useful for temporary tables
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 7. row ***************************
           Engine: ARCHIVE
          Support: YES
          Comment: Archive storage engine
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 8. row ***************************
           Engine: InnoDB
          Support: YES
          Comment: Supports transactions, row-level locking, and foreign keys
     Transactions: YES
               XA: YES
       Savepoints: YES
     *************************** 9. row ***************************
           Engine: MyISAM
          Support: DEFAULT
          Comment: Default engine as of MySQL 3.23 with great performance
     Transactions: NO
               XA: NO
       Savepoints: NO
     9 rows in set (0.00 sec)

The output from *Note `SHOW ENGINES': show-engines. may vary according
to the MySQL version used and other factors. The values shown in the
`Support' column indicate the server's level of support for the storage
engine, as shown in the following table.

*Value*     *Meaning*
`YES'       The engine is supported and is active
`DEFAULT'   Like `YES', plus this is the default engine
`NO'        The engine is not supported
`DISABLED'  The engine is supported but has been disabled

A value of `NO' means that the server was compiled without support for
the engine, so it cannot be activated at runtime.

A value of `DISABLED' occurs either because the server was started with
an option that disables the engine, or because not all options required
to enable it were given. In the latter case, the error log file should
contain a reason indicating why the option is disabled. See *Note
error-log::.

You might also see `DISABLED' for a storage engine if the server was
compiled to support it, but was started with a `--skip-ENGINE_NAME'
option.

All MySQL servers support `MyISAM' tables, because `MyISAM' is the
default storage engine.  It is not possible to disable `MyISAM'.

The `Transactions', `XA', and `Savepoints' columns indicate whether the
storage engine supports transactions, XA transactions, and savepoints,
respectively.


File: manual.info,  Node: show-errors,  Next: show-events,  Prev: show-engines,  Up: show

12.5.6.18 `SHOW ERRORS' Syntax
..............................

     SHOW ERRORS [LIMIT [OFFSET,] ROW_COUNT]
     SHOW COUNT(*) ERRORS

This statement is similar to *Note `SHOW WARNINGS': show-warnings,
except that instead of displaying errors, warnings, and notes, it
displays only errors.

The `LIMIT' clause has the same syntax as for the *Note `SELECT':
select. statement. See *Note select::.

The `SHOW COUNT(*) ERRORS' statement displays the number of errors. You
can also retrieve this number from the `error_count' variable:

     SHOW COUNT(*) ERRORS;
     SELECT @@error_count;

For more information, see *Note show-warnings::.


File: manual.info,  Node: show-events,  Next: show-function-code,  Prev: show-errors,  Up: show

12.5.6.19 `SHOW EVENTS' Syntax
..............................

     SHOW EVENTS [{FROM | IN} SCHEMA_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

In its simplest form, *Note `SHOW EVENTS': show-events.  lists all of
the events in the current schema:

     mysql> SELECT CURRENT_USER(), SCHEMA();
     +----------------+----------+
     | CURRENT_USER() | SCHEMA() |
     +----------------+----------+
     | jon@ghidora    | myschema |
     +----------------+----------+
     1 row in set (0.00 sec)

     mysql> SHOW EVENTS\G
     *************************** 1. row ***************************
                       Db: myschema
                     Name: e_daily
                  Definer: jon@ghidora
                Time zone: SYSTEM
                     Type: RECURRING
               Execute at: NULL
           Interval value: 10
           Interval field: SECOND
                   Starts: 2006-02-09 10:41:23
                     Ends: 0000-00-00 00:00:00
                   Status: ENABLED
               Originator: 0
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

The `LIKE' clause, if present, indicates which event names to match. The
`WHERE' clause can be given to select rows using more general
conditions, as discussed in *Note extended-show::.

The columns in the output of *Note `SHOW EVENTS': show-events. -- which
are similar to, but not identical to the columns in the *Note
`INFORMATION_SCHEMA.EVENTS': events-table. table -- are shown here:

   * `Db': The schema (database) on which the event is defined.

   * `Name': The name of the event.

   * `Time zone': The time zone in effect when schedule for the event
     was last modified. If the event's schedule has not been modified
     since the event was created, then this is the time zone that was
     in effect at the event's creation. The default value is `SYSTEM'.

   * `Definer': The user account (`USER_NAME@HOST_NAME') which created
     the event.

   * `Type': One of the two values `ONE TIME' (transient) or
     `RECURRING'.

   * `Execute At': The date and time when a transient event is set to
     execute. Shown as a *Note `DATETIME': datetime. value.

     For a recurring event, the value of this column is always `NULL'.

   * `Interval Value': For a recurring event, the number of intervals
     to wait between event executions.

     For a transient event, the value of this column is always `NULL'.

   * `Interval Field': The time units used for the interval which a
     recurring event waits before repeating.

     For a transient event, the value of this column is always `NULL'.

   * `Starts': The start date and time for a recurring event. This is
     displayed as a *Note `DATETIME': datetime. value, and is empty if
     no start date and time are defined for the event.

     For a transient event, the value of this column is always `NULL'.

   * `Ends': The end date and time for a recurring event. This is
     displayed as a *Note `DATETIME': datetime. value, and defaults to
     `'0000-00-00 00:00:00'' if no end date and time is defined for the
     event.

     For a transient event, the value of this column is always `NULL'.

   * `Status': The event status. One of `ENABLED', `DISABLED', or
     `SLAVESIDE_DISABLED'.

     `SLAVESIDE_DISABLED' indicates that the creation of the event
     occurred on another MySQL server acting as a replication master
     and replicated to the current MySQL server which is acting as a
     slave, but the event is not presently being executed on the slave.

   * `Originator': The server ID of the MySQL server on which the event
     was created. Defaults to 0.

   * `character_set_client' is the session value of the
     `character_set_client' system variable when the routine was
     created.  `collation_connection' is the session value of the
     `collation_connection' system variable when the routine was
     created. `Database Collation' is the collation of the database with
     which the routine is associated.

For more information about `SLAVE_DISABLED' and the `Originator'
column, see *Note replication-features-invoked::.

Note that the action statement is not shown in the output of *Note
`SHOW EVENTS': show-events.

These times are all given in terms of local time as determined by the
MySQL server's `time_zone' setting. See also *Note events-table::.

To see events for a different schema, you can use the `FROM' clause.
For example, if the `test' schema had been selected in the preceding
example, you could view events defined on `myschema' using the
following statement:

     SHOW EVENTS FROM myschema;

You can filter the list returned by this statement on the event name
using `LIKE' plus a pattern.

See also *Note events-table::.


File: manual.info,  Node: show-function-code,  Next: show-function-status,  Prev: show-events,  Up: show

12.5.6.20 `SHOW FUNCTION CODE' Syntax
.....................................

     SHOW FUNCTION CODE FUNC_NAME

This statement is similar to *Note `SHOW PROCEDURE CODE':
show-procedure-code. but for stored functions. See *Note
show-procedure-code::.


File: manual.info,  Node: show-function-status,  Next: show-grants,  Prev: show-function-code,  Up: show

12.5.6.21 `SHOW FUNCTION STATUS' Syntax
.......................................

     SHOW FUNCTION STATUS
         [LIKE 'PATTERN' | WHERE EXPR]

This statement is similar to *Note `SHOW PROCEDURE STATUS':
show-procedure-status. but for stored functions. See *Note
show-procedure-status::.


File: manual.info,  Node: show-grants,  Next: show-index,  Prev: show-function-status,  Up: show

12.5.6.22 `SHOW GRANTS' Syntax
..............................

     SHOW GRANTS [FOR USER]

This statement lists the *Note `GRANT': grant.  statement or statements
that must be issued to duplicate the privileges that are granted to a
MySQL user account. The account is named using the same format as for
the *Note `GRANT': grant. statement; for example,
`'jeffrey'@'localhost''. If you specify only the user name part of the
account name, a host name part of `'%'' is used. For additional
information about specifying account names, see *Note grant::.

     mysql> SHOW GRANTS FOR 'root'@'localhost';
     +---------------------------------------------------------------------+
     | Grants for root@localhost                                           |
     +---------------------------------------------------------------------+
     | GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
     +---------------------------------------------------------------------+

To list the privileges granted to the account that you are using to
connect to the server, you can use any of the following statements:

     SHOW GRANTS;
     SHOW GRANTS FOR CURRENT_USER;
     SHOW GRANTS FOR CURRENT_USER();

`SHOW GRANTS FOR CURRENT_USER' (or any of the equivalent syntaxes) is
used in `DEFINER' context, such as within a stored procedure that is
defined with `SQL SECURITY DEFINER'), the grants displayed are those of
the definer and not the invoker.

*Note `SHOW GRANTS': show-grants. displays only the privileges granted
explicitly to the named account. Other privileges might be available to
the account, but they are not displayed. For example, if an anonymous
account exists, the named account might be able to use its privileges,
but *Note `SHOW GRANTS': show-grants. will not display them.

*Note `SHOW GRANTS': show-grants. requires the `SELECT' privilege for
the `mysql' database.


File: manual.info,  Node: show-index,  Next: show-master-status,  Prev: show-grants,  Up: show

12.5.6.23 `SHOW INDEX' Syntax
.............................

     SHOW {INDEX | INDEXES | KEYS}
         {FROM | IN} TBL_NAME
         [{FROM | IN} DB_NAME]

*Note `SHOW INDEX': show-index. returns table index information. The
format resembles that of the `SQLStatistics' call in ODBC. This
statement requires some privilege for any column in the table.

*Note `SHOW INDEX': show-index. returns the following fields:

   * `Table'

     The name of the table.

   * `Non_unique'

     0 if the index cannot contain duplicates, 1 if it can.

   * `Key_name'

     The name of the index.

   * `Seq_in_index'

     The column sequence number in the index, starting with 1.

   * `Column_name'

     The column name.

   * `Collation'

     How the column is sorted in the index. In MySQL, this can have
     values ``A'' (Ascending) or `NULL' (Not sorted).

   * `Cardinality'

     An estimate of the number of unique values in the index.  This is
     updated by running *Note `ANALYZE TABLE': analyze-table. or *Note
     `myisamchk -a': myisamchk.  `Cardinality' is counted based on
     statistics stored as integers, so the value is not necessarily
     exact even for small tables. The higher the cardinality, the
     greater the chance that MySQL uses the index when doing joins.

   * `Sub_part'

     The number of indexed characters if the column is only partly
     indexed, `NULL' if the entire column is indexed.

   * `Packed'

     Indicates how the key is packed. `NULL' if it is not.

   * `Null'

     Contains `YES' if the column may contain `NULL'. If not, the
     column contains `NO'.

     Contains `YES' if the column may contain `NULL' values and `''' if
     not.

   * `Index_type'

     The index method used (`BTREE', `FULLTEXT', `HASH', `RTREE').

   * `Comment'

     Various remarks.

   * `Index_comment'

     Any comment provided for the index with a `COMMENT' attribute when
     the index was created.

You can use DB_NAME.TBL_NAME as an alternative to the `TBL_NAME FROM
DB_NAME' syntax. These two statements are equivalent:

     SHOW INDEX FROM mytable FROM mydb;
     SHOW INDEX FROM mydb.mytable;

You can also list a table's indexes with the *Note `mysqlshow -k
DB_NAME TBL_NAME': mysqlshow. command.


File: manual.info,  Node: show-master-status,  Next: show-open-tables,  Prev: show-index,  Up: show

12.5.6.24 `SHOW MASTER STATUS' Syntax
.....................................

     SHOW MASTER STATUS

Provides status information about the binary log files of the master.
Example:

     mysql> SHOW MASTER STATUS;
     +---------------+----------+--------------+------------------+
     | File          | Position | Binlog_Do_DB | Binlog_Ignore_DB |
     +---------------+----------+--------------+------------------+
     | mysql-bin.003 | 73       | test         | manual,mysql     |
     +---------------+----------+--------------+------------------+


File: manual.info,  Node: show-open-tables,  Next: show-plugins,  Prev: show-master-status,  Up: show

12.5.6.25 `SHOW OPEN TABLES' Syntax
...................................

     SHOW OPEN TABLES [{FROM | IN} DB_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

*Note `SHOW OPEN TABLES': show-open-tables. lists the non-`TEMPORARY'
tables that are currently open in the table cache. See *Note
table-cache::. The `LIKE' clause, if present, indicates which table
names to match. The `WHERE' clause can be given to select rows using
more general conditions, as discussed in *Note extended-show::.

*Note `SHOW OPEN TABLES': show-open-tables. returns the following
columns:

   * `Database'

     The database containing the table.

   * `Table'

     The table name.

   * `In_use'

     The number of table locks or lock requests there are for the
     table. For example, if one client acquires a lock for a table
     using `LOCK TABLE t1 WRITE', `In_use' will be 1. If another client
     issues `LOCK TABLE t1 WRITE' while the table remains locked, the
     client will block waiting for the lock, but the lock request
     causes `In_use' to be 2. If the count is zero, the table is open
     but not currently being used. `In_use' is also increased by the
     *Note `HANDLER ... OPEN': handler. statement and decreased by
     *Note `HANDLER ... CLOSE': handler.

   * `Name_locked'

     Whether the table name is locked. Name locking is used for
     operations such as dropping or renaming tables.

If you have no privileges for a table, it does not show up in the
output from *Note `SHOW OPEN TABLES': show-open-tables.


File: manual.info,  Node: show-plugins,  Next: show-privileges,  Prev: show-open-tables,  Up: show

12.5.6.26 `SHOW PLUGINS' Syntax
...............................

     SHOW PLUGINS

*Note `SHOW PLUGINS': show-plugins. displays information about known
plugins.

     mysql> SHOW PLUGINS;
     +------------+--------+----------------+---------+
     | Name       | Status | Type           | Library |
     +------------+--------+----------------+---------+
     | MEMORY     | ACTIVE | STORAGE ENGINE | NULL    |
     | MyISAM     | ACTIVE | STORAGE ENGINE | NULL    |
     | InnoDB     | ACTIVE | STORAGE ENGINE | NULL    |
     | ARCHIVE    | ACTIVE | STORAGE ENGINE | NULL    |
     | CSV        | ACTIVE | STORAGE ENGINE | NULL    |
     | BLACKHOLE  | ACTIVE | STORAGE ENGINE | NULL    |
     | FEDERATED  | ACTIVE | STORAGE ENGINE | NULL    |
     | MRG_MYISAM | ACTIVE | STORAGE ENGINE | NULL    |
     +------------+--------+----------------+---------+


File: manual.info,  Node: show-privileges,  Next: show-procedure-code,  Prev: show-plugins,  Up: show

12.5.6.27 `SHOW PRIVILEGES' Syntax
..................................

     SHOW PRIVILEGES

*Note `SHOW PRIVILEGES': show-privileges. shows the list of system
privileges that the MySQL server supports. The exact list of privileges
depends on the version of your server.

     mysql> SHOW PRIVILEGES\G
     *************************** 1. row ***************************
     Privilege: Alter
     Context: Tables
     Comment: To alter the table
     *************************** 2. row ***************************
     Privilege: Alter routine
     Context: Functions,Procedures
     Comment: To alter or drop stored functions/procedures
     *************************** 3. row ***************************
     Privilege: Create
     Context: Databases,Tables,Indexes
     Comment: To create new databases and tables
     *************************** 4. row ***************************
     Privilege: Create routine
     Context: Functions,Procedures
     Comment: To use CREATE FUNCTION/PROCEDURE
     *************************** 5. row ***************************
     Privilege: Create temporary tables
     Context: Databases
     Comment: To use CREATE TEMPORARY TABLE
     ...

Privileges belonging to a specific user are displayed by the *Note
`SHOW GRANTS': show-grants. statement. See *Note show-grants::, for
more information.


File: manual.info,  Node: show-procedure-code,  Next: show-procedure-status,  Prev: show-privileges,  Up: show

12.5.6.28 `SHOW PROCEDURE CODE' Syntax
......................................

     SHOW PROCEDURE CODE PROC_NAME

This statement is a MySQL extension that is available only for servers
that have been built with debugging support. It displays a
representation of the internal implementation of the named stored
procedure. A similar statement, *Note `SHOW FUNCTION CODE':
show-function-code, displays information about stored functions (see
*Note show-function-code::).

Both statements require that you be the owner of the routine or have
*Note `SELECT': select. access to the `mysql.proc' table.

If the named routine is available, each statement produces a result
set. Each row in the result set corresponds to one `instruction' in the
routine. The first column is `Pos', which is an ordinal number beginning
with 0. The second column is `Instruction', which contains an SQL
statement (usually changed from the original source), or a directive
which has meaning only to the stored-routine handler.

     mysql> DELIMITER //
     mysql> CREATE PROCEDURE p1 ()
         -> BEGIN
         ->   DECLARE fanta INT DEFAULT 55;
         ->   DROP TABLE t2;
         ->   LOOP
         ->     INSERT INTO t3 VALUES (fanta);
         ->     END LOOP;
         ->   END//
     Query OK, 0 rows affected (0.00 sec)

     mysql> SHOW PROCEDURE CODE p1//
     +-----+----------------------------------------+
     | Pos | Instruction                            |
     +-----+----------------------------------------+
     |   0 | set fanta@0 55                         |
     |   1 | stmt 9 "DROP TABLE t2"                 |
     |   2 | stmt 5 "INSERT INTO t3 VALUES (fanta)" |
     |   3 | jump 2                                 |
     +-----+----------------------------------------+
     4 rows in set (0.00 sec)

In this example, the non-executable `BEGIN' and `END' statements have
disappeared, and for the `DECLARE VARIABLE_NAME' statement, only the
executable part appears (the part where the default is assigned). For
each statement that is taken from source, there is a code word `stmt'
followed by a type (9 means `DROP', 5 means *Note `INSERT': insert, and
so on). The final row contains an instruction `jump 2', meaning `GOTO
instruction #2'.


File: manual.info,  Node: show-procedure-status,  Next: show-processlist,  Prev: show-procedure-code,  Up: show

12.5.6.29 `SHOW PROCEDURE STATUS' Syntax
........................................

     SHOW PROCEDURE STATUS
         [LIKE 'PATTERN' | WHERE EXPR]

This statement is a MySQL extension. It returns characteristics of a
stored procedure, such as the database, name, type, creator, creation
and modification dates, and character set information. A similar
statement, *Note `SHOW FUNCTION STATUS': show-function-status, displays
information about stored functions (see *Note show-function-status::).

The `LIKE' clause, if present, indicates which procedure or function
names to match. The `WHERE' clause can be given to select rows using
more general conditions, as discussed in *Note extended-show::.

     mysql> SHOW PROCEDURE STATUS LIKE 'sp1'\G
     *************************** 1. row ***************************
                       Db: test
                     Name: sp1
                     Type: PROCEDURE
                  Definer: testuser@localhost
                 Modified: 2004-08-03 15:29:37
                  Created: 2004-08-03 15:29:37
            Security_type: DEFINER
                  Comment:
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

`character_set_client' is the session value of the
`character_set_client' system variable when the routine was created.
`collation_connection' is the session value of the
`collation_connection' system variable when the routine was created.
`Database Collation' is the collation of the database with which the
routine is associated.

You can also get information about stored routines from the *Note
`ROUTINES': routines-table. table in `INFORMATION_SCHEMA'. See *Note
routines-table::.


File: manual.info,  Node: show-processlist,  Next: show-profile,  Prev: show-procedure-status,  Up: show

12.5.6.30 `SHOW PROCESSLIST' Syntax
...................................

     SHOW [FULL] PROCESSLIST

*Note `SHOW PROCESSLIST': show-processlist. shows you which threads are
running. You can also get this information from the `INFORMATION_SCHEMA'
*Note `PROCESSLIST': processlist-table. table or the *Note `mysqladmin
processlist': mysqladmin. command. If you have the `PROCESS' privilege,
you can see all threads. Otherwise, you can see only your own threads
(that is, threads associated with the MySQL account that you are
using). If you do not use the `FULL' keyword, only the first 100
characters of each statement are shown in the `Info' field.

MySQL Enterprise

Subscribers to MySQL Enterprise Monitor receive instant notification
and expert advice on resolution when there are too many concurrent
processes. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

This statement is very useful if you get the `too many connections'
error message and want to find out what is going on. MySQL reserves one
extra connection to be used by accounts that have the `SUPER'
privilege, to ensure that administrators should always be able to
connect and check the system (assuming that you are not giving this
privilege to all your users).

Threads can be killed with the *Note `KILL': kill. statement. See *Note
kill::.

Here is an example of what *Note `SHOW PROCESSLIST': show-processlist.
output looks like:

     mysql> SHOW FULL PROCESSLIST\G
     *************************** 1. row ***************************
     Id: 1
     User: system user
     Host:
     db: NULL
     Command: Connect
     Time: 1030455
     State: Waiting for master to send event
     Info: NULL
     *************************** 2. row ***************************
     Id: 2
     User: system user
     Host:
     db: NULL
     Command: Connect
     Time: 1004
     State: Has read all relay log; waiting for the slave
            I/O thread to update it
     Info: NULL
     *************************** 3. row ***************************
     Id: 3112
     User: replikator
     Host: artemis:2204
     db: NULL
     Command: Binlog Dump
     Time: 2144
     State: Has sent all binlog to slave; waiting for binlog to be updated
     Info: NULL
     *************************** 4. row ***************************
     Id: 3113
     User: replikator
     Host: iconnect2:45781
     db: NULL
     Command: Binlog Dump
     Time: 2086
     State: Has sent all binlog to slave; waiting for binlog to be updated
     Info: NULL
     *************************** 5. row ***************************
     Id: 3123
     User: stefan
     Host: localhost
     db: apollon
     Command: Query
     Time: 0
     State: NULL
     Info: SHOW FULL PROCESSLIST
     5 rows in set (0.00 sec)

The columns have the following meaning:

   * `Id'

     The connection identifier.

   * `User'

     The MySQL user who issued the statement. If this is `system user',
     it refers to a non-client thread spawned by the server to handle
     tasks internally.  This could be the I/O or SQL thread used on
     replication slaves or a delayed-row handler. `unauthenticated
     user' refers to a thread that has become associated with a client
     connection but for which authentication of the client user has not
     yet been done.  `event_scheduler' refers to the thread that
     monitors scheduled events. For `system user' or `event_scheduler',
     there is no host specified in the `Host' column.

   * `Host'

     The host name of the client issuing the statement (except for
     `system user' where there is no host).  *Note `SHOW PROCESSLIST':
     show-processlist. reports the host name for TCP/IP connections in
     `HOST_NAME:CLIENT_PORT' format to make it easier to determine
     which client is doing what.

   * `db'

     The default database, if one is selected, otherwise `NULL'.

   * `Command'

     The type of command the thread is executing. Descriptions for
     thread commands can be found at *Note thread-information::. The
     value of this column corresponds to the `COM_XXX' commands of the
     client/server protocol. See *Note server-status-variables::

   * `Time'

     The time in seconds that the thread has been in its current state.

   * `State'

     An action, event, or state that indicates what the thread is
     doing. Descriptions for `State' values can be found at *Note
     thread-information::.

     Most states correspond to very quick operations. If a thread stays
     in a given state for many seconds, there might be a problem that
     needs to be investigated.

     For the *Note `SHOW PROCESSLIST': show-processlist.  statement,
     the value of `State' is `NULL'.

   * `Info'

     The statement that the thread is executing, or `NULL' if it is not
     executing any statement. The statement might be the one sent to the
     server, or an innermost statement if the statement executes other
     statements. For example, if a `CALL p1()' statement executes a
     stored procedure `p1()', and the procedure is executing a *Note
     `SELECT': select. statement, the `Info' value shows the *Note
     `SELECT': select. statement.


File: manual.info,  Node: show-profile,  Next: show-profiles,  Prev: show-processlist,  Up: show

12.5.6.31 `SHOW PROFILE' Syntax
...............................

     SHOW PROFILES

The *Note `SHOW PROFILE': show-profile. statement display profiling
information that indicates resource usage for statements executed
during the course of the current session. It is used together with
*Note `SHOW PROFILES': show-profiles.; see *Note show-profiles::.


File: manual.info,  Node: show-profiles,  Next: show-slave-hosts,  Prev: show-profile,  Up: show

12.5.6.32 `SHOW PROFILES' Syntax
................................

     SHOW PROFILE [TYPE [, TYPE] ... ]
         [FOR QUERY N]
         [LIMIT ROW_COUNT [OFFSET OFFSET]]

     TYPE:
         ALL
       | BLOCK IO
       | CONTEXT SWITCHES
       | CPU
       | IPC
       | MEMORY
       | PAGE FAULTS
       | SOURCE
       | SWAPS

The *Note `SHOW PROFILES': show-profiles. and *Note `SHOW PROFILE':
show-profile. statements display profiling information that indicates
resource usage for statements executed during the course of the current
session.

Profiling is controlled by the `profiling' session variable, which has
a default value of 0 (`OFF').  Profiling is enabled by setting
`profiling' to 1 or `ON':

     mysql> SET profiling = 1;

*Note `SHOW PROFILES': show-profiles. displays a list of the most
recent statements sent to the master. The size of the list is
controlled by the `profiling_history_size' session variable, which has
a default value of 15. The maximum value is 100. Setting the value to 0
has the practical effect of disabling profiling.

All statements are profiled except *Note `SHOW PROFILES':
show-profiles. and *Note `SHOW PROFILE': show-profile, so you will find
neither of those statements in the profile list. Malformed statements
are profiled. For example, `SHOW PROFILING' is an illegal statement,
and a syntax error occurs if you try to execute it, but it will show up
in the profiling list.

*Note `SHOW PROFILE': show-profile. displays detailed information about
a single statement. Without the `FOR QUERY N' clause, the output
pertains to the most recently executed statement. If `FOR QUERY N' is
included, *Note `SHOW PROFILE': show-profile. displays information for
statement N. The values of N correspond to the `Query_ID' values
displayed by *Note `SHOW PROFILES': show-profiles.

The `LIMIT ROW_COUNT' clause may be given to limit the output to
ROW_COUNT rows. If `LIMIT' is given, `OFFSET OFFSET' may be added to
begin the output OFFSET rows into the full set of rows.

By default, *Note `SHOW PROFILE': show-profile. displays `Status' and
`Duration' columns. The `Status' values are like the `State' values
displayed by *Note `SHOW PROCESSLIST': show-processlist, althought there
might be some minor differences in interpretion for the two statements
for some status values (see *Note thread-information::).

Optional TYPE values may be specified to display specific additional
types of information:

   * `ALL' displays all information

   * `BLOCK IO' displays counts for block input and output operations

   * `CONTEXT SWITCHES' displays counts for voluntary and involuntary
     context switches

   * `CPU' displays user and system CPU usage times

   * `IPC' displays counts for messages sent and received

   * `MEMORY' is not currently implemented

   * `PAGE FAULTS' displays counts for major and minor page faults

   * `SOURCE' displays the names of functions from the source code,
     together with the name and line number of the file in which the
     function occurs

   * `SWAPS' displays swap counts

Profiling is enabled per session. When a session ends, its profiling
information is lost.

     mysql> SELECT @@profiling;
     +-------------+
     | @@profiling |
     +-------------+
     |           0 |
     +-------------+
     1 row in set (0.00 sec)

     mysql> SET profiling = 1;
     Query OK, 0 rows affected (0.00 sec)

     mysql> DROP TABLE IF EXISTS t1;
     Query OK, 0 rows affected, 1 warning (0.00 sec)

     mysql> CREATE TABLE T1 (id INT);
     Query OK, 0 rows affected (0.01 sec)

     mysql> SHOW PROFILES;
     +----------+----------+--------------------------+
     | Query_ID | Duration | Query                    |
     +----------+----------+--------------------------+
     |        0 | 0.000088 | SET PROFILING = 1        |
     |        1 | 0.000136 | DROP TABLE IF EXISTS t1  |
     |        2 | 0.011947 | CREATE TABLE t1 (id INT) |
     +----------+----------+--------------------------+
     3 rows in set (0.00 sec)

     mysql> SHOW PROFILE;
     +----------------------+----------+
     | Status               | Duration |
     +----------------------+----------+
     | checking permissions | 0.000040 |
     | creating table       | 0.000056 |
     | After create         | 0.011363 |
     | query end            | 0.000375 |
     | freeing items        | 0.000089 |
     | logging slow query   | 0.000019 |
     | cleaning up          | 0.000005 |
     +----------------------+----------+
     7 rows in set (0.00 sec)

     mysql> SHOW PROFILE FOR QUERY 1;
     +--------------------+----------+
     | Status             | Duration |
     +--------------------+----------+
     | query end          | 0.000107 |
     | freeing items      | 0.000008 |
     | logging slow query | 0.000015 |
     | cleaning up        | 0.000006 |
     +--------------------+----------+
     4 rows in set (0.00 sec)

     mysql> SHOW PROFILE CPU FOR QUERY 2;
     +----------------------+----------+----------+------------+
     | Status               | Duration | CPU_user | CPU_system |
     +----------------------+----------+----------+------------+
     | checking permissions | 0.000040 | 0.000038 |   0.000002 |
     | creating table       | 0.000056 | 0.000028 |   0.000028 |
     | After create         | 0.011363 | 0.000217 |   0.001571 |
     | query end            | 0.000375 | 0.000013 |   0.000028 |
     | freeing items        | 0.000089 | 0.000010 |   0.000014 |
     | logging slow query   | 0.000019 | 0.000009 |   0.000010 |
     | cleaning up          | 0.000005 | 0.000003 |   0.000002 |
     +----------------------+----------+----------+------------+
     7 rows in set (0.00 sec)

*Note*:

Profiling is only partially functional on some architectures.  For
values that depend on the `getrusage()' system call, `NULL' is returned
on systems such as Windows that do not support the call. In addition,
profiling is per process and not per thread. This means that activity
on threads within the server other than your own may affect the timing
information that you see.

*Note `SHOW PROFILES': show-profiles. and *Note `SHOW PROFILE':
show-profile. were added in MySQL 6.0.5.

You can also get profiling information from the *Note `PROFILING':
profiling-table. table in `INFORMATION_SCHEMA'. See *Note
profiling-table::. For example, the following queries produce the same
result:

     SHOW PROFILE FOR QUERY 2;

     SELECT STATE, FORMAT(DURATION, 6) AS DURATION
     FROM INFORMATION_SCHEMA.PROFILING
     WHERE QUERY_ID = 2 ORDER BY SEQ;


File: manual.info,  Node: show-slave-hosts,  Next: show-slave-status,  Prev: show-profiles,  Up: show

12.5.6.33 `SHOW SLAVE HOSTS' Syntax
...................................

     SHOW SLAVE HOSTS

Displays a list of replication slaves currently registered with the
master. Only slaves started with the `--report-host=HOST_NAME' option
are visible in this list.

The list is displayed on any server (not just the master server). The
output looks like this:

     mysql> SHOW SLAVE HOSTS;
     +------------+-----------+------+-----------+
     | Server_id  | Host      | Port | Master_id |
     +------------+-----------+------+-----------+
     |  192168010 | iconnect2 | 3306 | 192168011 |
     | 1921680101 | athena    | 3306 | 192168011 |
     +------------+-----------+------+-----------+

   * `Server_id': The unique server ID of the slave server, as
     configured in the server's option file, or on the command line with
     `--server-id=VALUE'.

   * `Host': The host name of the slave server, as configured in the
     server's option file, or on the command line with
     `--report-host=HOST_NAME'.  Note that this can differ from the
     machine name as configured in the operating system.

   * `Port': The port the slave server is listening on.

   * `Master_id': The unique server ID of the master server that the
     slave server is replicating from.

Some MySQL versions report another variable, `Rpl_recovery_rank'. This
variable was never used, and was eventually removed.


File: manual.info,  Node: show-slave-status,  Next: show-status,  Prev: show-slave-hosts,  Up: show

12.5.6.34 `SHOW SLAVE STATUS' Syntax
....................................

     SHOW SLAVE STATUS

This statement provides status information on essential parameters of
the slave threads. If you issue this statement using the *Note `mysql':
mysql. client, you can use a `\G' statement terminator rather than a
semicolon to obtain a more readable vertical layout:

     mysql> SHOW SLAVE STATUS\G
     *************************** 1. row ***************************
                    Slave_IO_State: Waiting for master to send event
                       Master_Host: localhost
                       Master_User: root
                       Master_Port: 3306
                     Connect_Retry: 3
                   Master_Log_File: gbichot-bin.005
               Read_Master_Log_Pos: 79
                    Relay_Log_File: gbichot-relay-bin.005
                     Relay_Log_Pos: 548
             Relay_Master_Log_File: gbichot-bin.005
                  Slave_IO_Running: Yes
                 Slave_SQL_Running: Yes
                   Replicate_Do_DB:
               Replicate_Ignore_DB:
                        Last_Errno: 0
                        Last_Error:
                      Skip_Counter: 0
               Exec_Master_Log_Pos: 79
                   Relay_Log_Space: 552
                   Until_Condition: None
                    Until_Log_File:
                     Until_Log_Pos: 0
                Master_SSL_Allowed: No
                Master_SSL_CA_File:
                Master_SSL_CA_Path:
                   Master_SSL_Cert:
                 Master_SSL_Cipher:
                    Master_SSL_Key:
             Seconds_Behind_Master: 8
     Master_SSL_Verify_Server_Cert: No
                     Last_IO_Errno: 0
                     Last_IO_Error:
                    Last_SQL_Errno: 0
                    Last_SQL_Error:
       Replicate_Ignore_Server_Ids: 0

*Note `SHOW SLAVE STATUS': show-slave-status. returns the following
fields:

   * `Slave_IO_State'

     A copy of the `State' field of the output of *Note `SHOW
     PROCESSLIST': show-processlist. for the slave I/O thread. This
     tells you what the thread is doing: trying to connect to the
     master, waiting for events from the master, reconnecting to the
     master, and so on. Possible states are listed in *Note
     replication-implementation-details::. It is necessary to check
     this field for older versions of MySQL which allowed the thread to
     continue running while unsuccessfully trying to connect to the
     master. If it is running, there is no problem; if it is not, you
     can find the error in the `Last_Error' field (described below).

   * `Master_Host'

     The current master host.

   * `Master_User'

     The current user used to connect to the master.

   * `Master_Port'

     The current master port.

   * `Connect_Retry'

     The number of seconds between connect retries (default 60).  This
     may be set with the *Note `CHANGE MASTER TO': change-master-to.
     statement.

   * `Master_Log_File'

     The name of the master binary log file from which the I/O thread
     is currently reading.

   * `Read_Master_Log_Pos'

     The position up to which the I/O thread has read in the current
     master binary log.

   * `Relay_Log_File'

     The name of the relay log file from which the SQL thread is
     currently reading and executing.

   * `Relay_Log_Pos'

     The position up to which the SQL thread has read and executed in
     the current relay log.

   * `Relay_Master_Log_File'

     The name of the master binary log file containing the most recent
     event executed by the SQL thread.

   * `Slave_IO_Running'

     Whether the I/O thread is started and has connected successfully
     to the master. Internally, the state of this thread is represented
     by one of 3 values; these are shown with their meanings in the
     following list:

        * `MYSQL_SLAVE_NOT_RUN'

          The slave I/O thread is not running.

        * `MYSQL_SLAVE_RUN_NOT_CONNECT'

          The slave I/O thread is running, but is not connected to a
          replication master.

        * `MYSQL_SLAVE_RUN_CONNECT'

          The slave I/O thread is running, and is connected to a
          replication master.

     Different values are displayed for `Slave_IO_running' depending on
     the slave I/O thread's actual state and the version of MySQL used
     on the replication slave, as shown in the following table.

     MySQL   `MYSQL_SLAVE_NOT_RUN'`MYSQL_SLAVE_RUN_NOT_CONNECT'`MYSQL_SLAVE_RUN_CONNECT'
     Version                                           
     4.1     `No'                 `Yes'                `Yes'
     (4.1.13                                           
     and                                               
     earlier);                                          
     5.0                                               
     (5.0.11                                           
     and                                               
     earlier)                                          
     4.1     `No'                 `No'                 `Yes'
     (4.1.14                                           
     and                                               
     later);                                           
     5.0                                               
     (5.0.12                                           
     and                                               
     later)                                            
     5.1     `No'                 `No'                 `Yes'
     (all)                                             
     6.0     `No'                 `No'                 `Yes'
     (6.0.10                                           
     and                                               
     earlier)                                          
     6.0     `No'                 `Connecting'         `Yes'
     (6.0.11                                           
     and                                               
     later)                                            

     Beginning with MySQL 6.0.11, the value of the `Slave_running'
     system status variable corresponds with this value. (Bug#30703
     (http://bugs.mysql.com/30703))

   * `Slave_SQL_Running'

     Whether the SQL thread is started.

   * `Replicate_Do_DB', `Replicate_Ignore_DB'

     The lists of databases that were specified with the
     `--replicate-do-db' and `--replicate-ignore-db' options, if any.

   * `Replicate_Do_Table', `Replicate_Ignore_Table',
     `Replicate_Wild_Do_Table', `Replicate_Wild_Ignore_Table'

     The lists of tables that were specified with the
     `--replicate-do-table', `--replicate-ignore-table',
     `--replicate-wild-do-table', and `--replicate-wild-ignore-table'
     options, if any.

   * `Last_Errno', `Last_Error'

     These columns are aliases for `Last_SQL_Errno' and
     `Last_SQL_Error'.

     Beginning with MySQL 6.0.10, issuing *Note `RESET MASTER':
     reset-master. or *Note `RESET SLAVE': reset-slave. resets the
     values shown in these columns.

     *Note*:

     When the slave SQL thread receives an error, it reports the error
     first, then stops the SQL thread. This means that there is a small
     window of time during which `SHOW SLAVE STATUS' shows a nonzero
     value for `Last_SQL_Errno' even though `Slave_SQL_Running' still
     displays `Yes'.

   * `Skip_Counter'

     The most recently used value for `SQL_SLAVE_SKIP_COUNTER'.

   * `Exec_Master_Log_Pos'

     The position of the last event executed by the SQL thread from the
     master's binary log (`Relay_Master_Log_File').
     (`Relay_Master_Log_File', `Exec_Master_Log_Pos') in the master's
     binary log corresponds to (`Relay_Log_File', `Relay_Log_Pos') in
     the relay log.

   * `Relay_Log_Space'

     The total combined size of all existing relay logs.

   * `Until_Condition', `Until_Log_File', `Until_Log_Pos'

     The values specified in the `UNTIL' clause of the *Note `START
     SLAVE': start-slave. statement.

     `Until_Condition' has these values:

        * `None' if no `UNTIL' clause was specified

        * `Master' if the slave is reading until a given position in
          the master's binary logs

        * `Relay' if the slave is reading until a given position in its
          relay logs

     `Until_Log_File' and `Until_Log_Pos' indicate the log file name
     and position values that define the point at which the SQL thread
     stops executing.

   * `Master_SSL_Allowed', `Master_SSL_CA_File', `Master_SSL_CA_Path',
     `Master_SSL_Cert', `Master_SSL_Cipher', `Master_SSL_Key'

     These fields show the SSL parameters used by the slave to connect
     to the master, if any.

     `Master_SSL_Allowed' has these values:

        * `Yes' if an SSL connection to the master is permitted

        * `No' if an SSL connection to the master is not permitted

        * `Ignored' if an SSL connection is permitted but the slave
          server does not have SSL support enabled

     The values of the other SSL-related fields correspond to the
     values of the `MASTER_SSL_CA', `MASTER_SSL_CAPATH',
     `MASTER_SSL_CERT', `MASTER_SSL_CIPHER', `MASTER_SSL_KEY', and
     `MASTER_SSL_VERIFY_SERVER_CERT' options to the *Note `CHANGE
     MASTER TO': change-master-to.  statement. See *Note
     change-master-to::.

   * `Seconds_Behind_Master'

     This field is an indication of how `late' the slave is:

        * When the slave SQL thread is actively running (processing
          updates), this field is the number of seconds that have
          elapsed since the timestamp of the most recent event on the
          master executed by that thread.

        * When the SQL thread has caught up to the slave I/O thread and
          goes idle waiting for more events from the I/O thread, this
          field is zero.

     In essence, this field measures the time difference in seconds
     between the slave SQL thread and the slave I/O thread.

     If the network connection between master and slave is fast, the
     slave I/O thread is very close to the master, so this field is a
     good approximation of how late the slave SQL thread is compared to
     the master. If the network is slow, this is _not_ a good
     approximation; the slave SQL thread may quite often be caught up
     with the slow-reading slave I/O thread, so `Seconds_Behind_Master'
     often shows a value of 0, even if the I/O thread is late compared
     to the master.  In other words, _this column is useful only for
     fast networks_.

     This time difference computation works even though the master and
     slave do not have identical clocks (the clock difference is
     computed when the slave I/O thread starts, and assumed to remain
     constant from then on).  `Seconds_Behind_Master' is `NULL' (which
     means `unknown') if the slave SQL thread is not running, or if the
     slave I/O thread is not running or not connected to master. For
     example if the slave I/O thread is sleeping for the number of
     seconds set by the *Note `CHANGE MASTER TO': change-master-to.
     statement (default 60) before reconnecting, `NULL' is shown, as
     the slave cannot know what the master is doing, and so cannot say
     reliably how late it is.

     This field has one limitation. The timestamp is preserved through
     replication, which means that, if a master M1 is itself a slave of
     M0, any event from M1's binlog which originates in replicating an
     event from M0's binlog has the timestamp of that event. This
     enables MySQL to replicate *Note `TIMESTAMP': datetime.
     successfully.  However, the problem for `Seconds_Behind_Master' is
     that if M1 also receives direct updates from clients, the value
     randomly deviates, because sometimes the last M1's event is from M0
     and sometimes it is the most recent timestamp from a direct update.

   * `Last_IO_Errno', `Last_IO_Error'

     The error number and error message of the last error that caused
     the I/O thread to stop. An error number of 0 and message of the
     empty string mean `no error.' If the `Last_IO_Error' value is not
     empty, it also appears as a message in the slave's error log.

     Beginning with MySQL 6.0.10, issuing *Note `RESET MASTER':
     reset-master. or *Note `RESET SLAVE': reset-slave. resets the
     values shown in these columns.

   * `Last_SQL_Errno', `Last_SQL_Error'

     The error number and error message of the last error that caused
     the SQL thread to stop. An error number of 0 and message of the
     empty string mean `no error.' If the `Last_IO_Error' value is not
     empty, it also appears as a message in the slave's error log.

     Example:

          Last_SQL_Errno: 1051
          Last_SQL_Error: error 'Unknown table 'z'' on query 'drop table z'

     The message indicates that the table `z' existed on the master and
     was dropped there, but it did not exist on the slave, so *Note
     `DROP TABLE': drop-table. failed on the slave. (This might occur,
     for example, if you forget to copy the table to the slave when
     setting up replication.)

     Beginning with MySQL 6.0.10, issuing *Note `RESET MASTER':
     reset-master. or *Note `RESET SLAVE': reset-slave. resets the
     values shown in these columns.

   * `Replicate_Ignore_Server_Ids'

     Beginning with MySQL 6.0.10, you can tell a slave to ignore events
     from 0 or more masters using the `IGNORE_SERVER_IDS' option in a
     *Note `CHANGE MASTER TO': change-master-to. statement.  This is
     normally of interest only when using a circular or other
     multi-master replication setup.

     The message shown for `Replicate_Ignore_Server_Ids' consists of a
     space-delimited list of 1 or more numbers, the first number
     indicating the number of servers to be ignored; if not 0 (the
     default), then this number is followed by the actual server IDs.
     For example, if a slave has been told to ignore masters having the
     server IDs 2, 6, and 9 (using a *Note `CHANGE MASTER TO':
     change-master-to. statement containing the option
     `IGNORE_SERVER_IDS = (2,6,9)'), then this row appears as shown
     here:

            Replicate_Ignore_Server_Ids: 3 2 6 9


File: manual.info,  Node: show-status,  Next: show-table-status,  Prev: show-slave-status,  Up: show

12.5.6.35 `SHOW STATUS' Syntax
..............................

     SHOW [GLOBAL | SESSION] STATUS
         [LIKE 'PATTERN' | WHERE EXPR]

*Note `SHOW STATUS': show-status. provides server status information.
This information also can be obtained using the *Note `mysqladmin
extended-status': mysqladmin. command. The `LIKE' clause, if present,
indicates which variable names to match. The `WHERE' clause can be
given to select rows using more general conditions, as discussed in
*Note extended-show::.

Partial output is shown here. The list of names and values may be
different for your server. The meaning of each variable is given in
*Note server-status-variables::.

     mysql> SHOW STATUS;
     +--------------------------+------------+
     | Variable_name            | Value      |
     +--------------------------+------------+
     | Aborted_clients          | 0          |
     | Aborted_connects         | 0          |
     | Bytes_received           | 155372598  |
     | Bytes_sent               | 1176560426 |
     | Connections              | 30023      |
     | Created_tmp_disk_tables  | 0          |
     | Created_tmp_tables       | 8340       |
     | Created_tmp_files        | 60         |
     ...
     | Open_tables              | 1          |
     | Open_files               | 2          |
     | Open_streams             | 0          |
     | Opened_tables            | 44600      |
     | Questions                | 2026873    |
     ...
     | Table_locks_immediate    | 1920382    |
     | Table_locks_waited       | 0          |
     | Threads_cached           | 0          |
     | Threads_created          | 30022      |
     | Threads_connected        | 1          |
     | Threads_running          | 1          |
     | Uptime                   | 80380      |
     +--------------------------+------------+

With a `LIKE' clause, the statement displays only rows for those
variables with names that match the pattern:

     mysql> SHOW STATUS LIKE 'Key%';
     +--------------------+----------+
     | Variable_name      | Value    |
     +--------------------+----------+
     | Key_blocks_used    | 14955    |
     | Key_read_requests  | 96854827 |
     | Key_reads          | 162040   |
     | Key_write_requests | 7589728  |
     | Key_writes         | 3813196  |
     +--------------------+----------+

With the `GLOBAL' modifier, *Note `SHOW STATUS': show-status. displays
the status values for all connections to MySQL. With `SESSION', it
displays the status values for the current connection. If no modifier
is present, the default is `SESSION'. `LOCAL' is a synonym for
`SESSION'.

Some status variables have only a global value. For these, you get the
same value for both `GLOBAL' and `SESSION'. The scope for each status
variable is listed at *Note server-status-variables::.

MySQL Enterprise

Status variables provide valuable clues to the state of your servers.
For expert interpretation of the information provided by status
variables, subscribe to the MySQL Enterprise Monitor. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: show-table-status,  Next: show-tables,  Prev: show-status,  Up: show

12.5.6.36 `SHOW TABLE STATUS' Syntax
....................................

     SHOW TABLE STATUS [{FROM | IN} DB_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

*Note `SHOW TABLE STATUS': show-table-status. works likes *Note `SHOW
TABLES': show-tables, but provides a lot of information about each
non-`TEMPORARY' table. You can also get this list using the *Note
`mysqlshow --status DB_NAME': mysqlshow. command.  The `LIKE' clause,
if present, indicates which table names to match. The `WHERE' clause
can be given to select rows using more general conditions, as discussed
in *Note extended-show::.

This statement also displays information about views.

*Note `SHOW TABLE STATUS': show-table-status. returns the following
fields:

   * `Name'

     The name of the table.

   * `Engine'

     The storage engine for the table. See *Note storage-engines::.

   * `Version'

     The version number of the table's `.frm' file.

   * `Row_format'

     The row storage format (`Fixed', `Dynamic', `Compressed',
     `Redundant', `Compact').  The format of `InnoDB' tables is reported
     as `Redundant' or `Compact'.

   * `Rows'

     The number of rows. Some storage engines, such as `MyISAM', store
     the exact count. For other storage engines, such as `InnoDB', this
     value is an approximation, and may vary from the actual value by
     as much as 40 to 50%. In such cases, use `SELECT COUNT(*)' to
     obtain an accurate count.

     The `Rows' value is `NULL' for tables in the `INFORMATION_SCHEMA'
     database.

   * `Avg_row_length'

     The average row length.

   * `Data_length'

     The length of the data file.

   * `Max_data_length'

     The maximum length of the data file. This is the total number of
     bytes of data that can be stored in the table, given the data
     pointer size used.

   * `Index_length'

     The length of the index file.

   * `Data_free'

     The number of allocated but unused bytes.

     Beginning with MySQL 6.0.5, this information is also shown for
     `InnoDB' tables (previously, it was in the `Comment' value).
     `InnoDB' tables report the free space of the tablespace to which
     the table belongs. For a table located in the shared tablespace,
     this is the free space of the shared tablespace. If you are using
     multiple tablespaces and the table has its own tablespace, the
     free space is for only that table. Free space means the number of
     completely free 1MB extents minus a safety margin. Even if free
     space displays as 0, it may be possible to insert rows as long as
     new extents need not be allocated.

     For partitioned tables, this value is only an estimate and may not
     be absolutely correct. A more accurate method of obtaining this
     information in such cases is to query the
     `INFORMATION_SCHEMA.PARTITIONS' table, as shown in this example:

          SELECT    SUM(DATA_FREE)
              FROM  INFORMATION_SCHEMA.PARTITIONS
              WHERE TABLE_SCHEMA = 'mydb'
              AND   TABLE_NAME   = 'mytable';

     For more information, see *Note partitions-table::.

   * `Auto_increment'

     The next `AUTO_INCREMENT' value.

   * `Create_time'

     When the table was created.

   * `Update_time'

     When the data file was last updated. For some storage engines,
     this value is `NULL'. For example, `InnoDB' stores multiple tables
     in its tablespace and the data file timestamp does not apply. For
     `MyISAM', the data file timestamp is used; however, on Windows the
     timestamp is not updated by updates so the value is inaccurate.

   * `Check_time'

     When the table was last checked. Not all storage engines update
     this time, in which case the value is always `NULL'.

   * `Collation'

     The table's character set and collation.

   * `Checksum'

     The live checksum value (if any).

   * `Create_options'

     Extra options used with *Note `CREATE TABLE': create-table. The
     original options supplied when *Note `CREATE TABLE': create-table.
     is called are retained and the options reported here may differ
     from the active table settings and options.

   * `Comment'

     The comment used when creating the table (or information as to why
     MySQL could not access the table information).

     Before MySQL 6.0.5, free space for `InnoDB' tables is reported in
     the comment. As of 6.0.5, it is reported in the `Data_free' column.

For `MEMORY' tables, the `Data_length', `Max_data_length', and
`Index_length' values approximate the actual amount of allocated
memory. The allocation algorithm reserves memory in large amounts to
reduce the number of allocation operations.

For views, all the fields displayed by *Note `SHOW TABLE STATUS':
show-table-status. are `NULL' except that `Name' indicates the view
name and `Comment' says `view'.


File: manual.info,  Node: show-tables,  Next: show-triggers,  Prev: show-table-status,  Up: show

12.5.6.37 `SHOW TABLES' Syntax
..............................

     SHOW [FULL] TABLES [{FROM | IN} DB_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

*Note `SHOW TABLES': show-tables. lists the non-`TEMPORARY' tables in a
given database. You can also get this list using the *Note `mysqlshow
DB_NAME': mysqlshow. command. The `LIKE' clause, if present, indicates
which table names to match. The `WHERE' clause can be given to select
rows using more general conditions, as discussed in *Note
extended-show::.

This statement also lists any views in the database. The `FULL'
modifier is supported such that `SHOW FULL TABLES' displays a second
output column. Values for the second column are `BASE TABLE' for a
table and `VIEW' for a view.

If you have no privileges for a base table or view, it does not show up
in the output from *Note `SHOW TABLES': show-tables. or *Note
`mysqlshow db_name': mysqlshow.


File: manual.info,  Node: show-triggers,  Next: show-variables,  Prev: show-tables,  Up: show

12.5.6.38 `SHOW TRIGGERS' Syntax
................................

     SHOW TRIGGERS [{FROM | IN} DB_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

*Note `SHOW TRIGGERS': show-triggers. lists the triggers currently
defined for tables in a database (the default database unless a `FROM'
clause is given). This statement requires the `TRIGGER' privilege. The
`LIKE' clause, if present, indicates which table names to match and
causes the statement to display triggers for those tables. The `WHERE'
clause can be given to select rows using more general conditions, as
discussed in *Note extended-show::.

For the trigger `ins_sum' as defined in *Note triggers::, the output of
this statement is as shown here:

     mysql> SHOW TRIGGERS LIKE 'acc%'\G
     *************************** 1. row ***************************
                  Trigger: ins_sum
                    Event: INSERT
                    Table: account
                Statement: SET @sum = @sum + NEW.amount
                   Timing: BEFORE
                  Created: NULL
                 sql_mode:
                  Definer: myname@localhost
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

`character_set_client' is the session value of the
`character_set_client' system variable when the trigger was created.
`collation_connection' is the session value of the
`collation_connection' system variable when the trigger was created.
`Database Collation' is the collation of the database with which the
trigger is associated.

*Note*:

When using a `LIKE' clause with *Note `SHOW TRIGGERS': show-triggers,
the expression to be matched (EXPR) is compared with the name of the
table on which the trigger is declared, and not with the name of the
trigger:

     mysql> SHOW TRIGGERS LIKE 'ins%';
     Empty set (0.01 sec)

A brief explanation of the columns in the output of this statement is
shown here:

   * `Trigger'

     The name of the trigger.

   * `Event'

     The event that causes trigger activation: one of `'INSERT'',
     `'UPDATE'', or `'DELETE''.

   * `Table'

     The table for which the trigger is defined.

   * `Statement'

     The statement to be executed when the trigger is activated.  This
     is the same as the text shown in the `ACTION_STATEMENT' column of
     *Note `INFORMATION_SCHEMA.TRIGGERS': triggers-table.

   * `Timing'

     One of the two values `'BEFORE'' or `'AFTER''.

   * `Created'

     Currently, the value of this column is always `NULL'.

   * `sql_mode'

     The SQL mode in effect when the trigger executes.

   * `Definer'

     The account that created the trigger.

See also *Note triggers-table::.


File: manual.info,  Node: show-variables,  Next: show-warnings,  Prev: show-triggers,  Up: show

12.5.6.39 `SHOW VARIABLES' Syntax
.................................

     SHOW [GLOBAL | SESSION] VARIABLES
         [LIKE 'PATTERN' | WHERE EXPR]

*Note `SHOW VARIABLES': show-variables. shows the values of MySQL
system variables. This information also can be obtained using the *Note
`mysqladmin variables': mysqladmin. command. The `LIKE' clause, if
present, indicates which variable names to match. The `WHERE' clause
can be given to select rows using more general conditions, as discussed
in *Note extended-show::.

With the `GLOBAL' modifier, *Note `SHOW VARIABLES': show-variables.
displays the values that are used for new connections to MySQL. With
`SESSION', it displays the values that are in effect for the current
connection. If no modifier is present, the default is `SESSION'.
`LOCAL' is a synonym for `SESSION'.

If the default system variable values are unsuitable, you can set them
using command options when *Note `mysqld': mysqld.  starts, and most
can be changed at runtime with the *Note `SET': set-option.  statement.
See *Note using-system-variables::, and *Note set-option::.

Partial output is shown here. The list of names and values may be
different for your server.  *Note server-system-variables::, describes
the meaning of each variable, and *Note server-parameters::, provides
information about tuning them.

     +-------------------------------------------+-------------------------------------------------+
     | Variable_name                             | Value                                           |
     +-------------------------------------------+-------------------------------------------------+
     | archive_aio                               | OFF                                             |
     | auto_increment_increment                  | 1                                               |
     | auto_increment_offset                     | 1                                               |
     | autocommit                                | ON                                              |
     | automatic_sp_privileges                   | ON                                              |
     | back_log                                  | 50                                              |
     | backup_history_log                        | ON                                              |
     | backup_history_log_file                   | /home/jon/bin/mysql-6.0/var/backup_history.log  |
     | backup_progress_log                       | ON                                              |
     | backup_progress_log_file                  | /home/jon/bin/mysql-6.0/var/backup_progress.log |
     | backup_wait_timeout                       | 50                                              |
     | backupdir                                 | /home/jon/bin/mysql-6.0/var/                    |
     | basedir                                   | /home/jon/bin/mysql-6.0/                        |
     | big_tables                                | OFF                                             |
     | binlog_cache_size                         | 32768                                           |
     | binlog_format                             | MIXED                                           |
     | bulk_insert_buffer_size                   | 8388608                                         |
     | character_set_client                      | latin1                                          |
     | character_set_connection                  | latin1                                          |
     | character_set_database                    | latin1                                          |
     | character_set_filesystem                  | binary                                          |
     | character_set_results                     | latin1                                          |
     | character_set_server                      | latin1                                          |
     | character_set_system                      | utf8                                            |
     ...
     | falcon_record_memory_max                  | 262144000                                       |
     | falcon_record_scavenge_floor              | 50                                              |
     | falcon_record_scavenge_threshold          | 67                                              |
     | falcon_scavenge_schedule                  | 15,45 * * * * *                                 |
     | falcon_serial_log_block_size              | 0                                               |
     | falcon_serial_log_buffers                 | 20                                              |
     | falcon_serial_log_dir                     | /home/jon/bin/mysql-6.0/var/                    |
     | falcon_serial_log_file_size               | 10485760                                        |
     | falcon_serial_log_priority                | 1                                               |
     | falcon_support_xa                         | OFF                                             |
     | falcon_use_deferred_index_hash            | OFF                                             |
     | falcon_use_sectorcache                    | OFF                                             |
     | falcon_use_supernodes                     | ON                                              |
     | flush                                     | OFF                                             |
     | flush_time                                | 0                                               |
     | foreign_key_checks                        | ON                                              |
     | ft_boolean_syntax                         | + -><()~*:""&|                                  |
     | ft_max_word_len                           | 84                                              |
     | ft_min_word_len                           | 4                                               |
     | ft_query_expansion_limit                  | 20                                              |
     ...
     | have_partitioning                         | YES                                             |
     | have_query_cache                          | YES                                             |
     | have_rtree_keys                           | YES                                             |
     | have_ssl                                  | NO                                              |
     | have_symlink                              | YES                                             |
     | hostname                                  | tonfisk                                         |
     | identity                                  | 0                                               |
     | init_connect                              |                                                 |
     | init_file                                 |                                                 |
     | init_slave                                |                                                 |
     | innodb_adaptive_hash_index                | ON                                              |
     | innodb_additional_mem_pool_size           | 1048576                                         |
     | innodb_autoextend_increment               | 8                                               |
     | innodb_autoinc_lock_mode                  | 1                                               |
     | innodb_buffer_pool_size                   | 8388608                                         |
     | innodb_checksums                          | ON                                              |
     | innodb_commit_concurrency                 | 0                                               |
     | innodb_concurrency_tickets                | 500                                             |
     | innodb_data_file_path                     | ibdata1:10M:autoextend                          |
     | innodb_data_home_dir                      |                                                 |
     | innodb_doublewrite                        | ON                                              |
     | innodb_fast_shutdown                      | 1                                               |
     | innodb_file_io_threads                    | 4                                               |
     | innodb_file_per_table                     | OFF                                             |
     ...
     | maria_max_sort_file_size                  | 9223372036853727232                             |
     | maria_page_checksum                       | ON                                              |
     | maria_pagecache_age_threshold             | 300                                             |
     | maria_pagecache_buffer_size               | 8384512                                         |
     | maria_pagecache_division_limit            | 100                                             |
     | maria_recover                             | OFF                                             |
     | maria_repair_threads                      | 1                                               |
     | maria_sort_buffer_size                    | 8388608                                         |
     | maria_stats_method                        | nulls_unequal                                   |
     | maria_sync_log_dir                        | NEWFILE                                         |
     | max_allowed_packet                        | 1048576                                         |
     | max_binlog_cache_size                     | 18446744073709547520                            |
     | max_binlog_size                           | 1073741824                                      |
     | max_connect_errors                        | 10                                              |
     | max_connections                           | 151                                             |
     | max_delayed_threads                       | 20                                              |
     | max_error_count                           | 64                                              |
     | max_heap_table_size                       | 16777216                                        |
     | max_insert_delayed_threads                | 20                                              |
     | max_join_size                             | 18446744073709551615                            |
     | max_length_for_sort_data                  | 1024                                            |
     | max_prepared_stmt_count                   | 16382                                           |
     | max_relay_log_size                        | 0                                               |
     | max_seeks_for_key                         | 18446744073709551615                            |
     | max_sort_length                           | 1024                                            |
     | max_sp_recursion_depth                    | 0                                               |
     | max_tmp_tables                            | 32                                              |
     | max_user_connections                      | 0                                               |
     | max_write_lock_count                      | 18446744073709551615                            |
     ...
     | query_cache_wlock_invalidate              | OFF                                             |
     | query_prealloc_size                       | 8192                                            |
     | rand_seed1                                |                                                 |
     | rand_seed2                                |                                                 |
     | range_alloc_block_size                    | 4096                                            |
     | read_buffer_size                          | 131072                                          |
     | read_only                                 | OFF                                             |
     | read_rnd_buffer_size                      | 262144                                          |
     | relay_log                                 |                                                 |
     | relay_log_index                           |                                                 |
     | relay_log_info_file                       | relay-log.info                                  |
     | relay_log_purge                           | ON                                              |
     | relay_log_space_limit                     | 0                                               |
     | report_host                               |                                                 |
     | report_password                           |                                                 |
     ...
     | thread_stack                              | 262144                                          |
     | time_format                               | %H:%i:%s                                        |
     | time_zone                                 | SYSTEM                                          |
     | timed_mutexes                             | OFF                                             |
     | timestamp                                 | 1233608154                                      |
     | tmp_table_size                            | 16777216                                        |
     | tmpdir                                    | /tmp                                            |
     | transaction_alloc_block_size              | 8192                                            |
     | transaction_prealloc_size                 | 4096                                            |
     | tx_isolation                              | REPEATABLE-READ                                 |
     | unique_checks                             | ON                                              |
     | updatable_views_with_limit                | YES                                             |
     | version                                   | 6.0.10-alpha                                    |
     | version_comment                           | Source distribution                             |
     | version_compile_machine                   | x86_64                                          |
     | version_compile_os                        | suse-linux-gnu                                  |
     | wait_timeout                              | 28800                                           |
     | warning_count                             | 0                                               |
     +-------------------------------------------+-------------------------------------------------+

With a `LIKE' clause, the statement displays only rows for those
variables with names that match the pattern. To obtain the row for a
specific variable, use a `LIKE' clause as shown:

     SHOW VARIABLES LIKE 'max_join_size';
     SHOW SESSION VARIABLES LIKE 'max_join_size';

To get a list of variables whose name match a pattern, use the ``%''
wildcard character in a `LIKE' clause:

     SHOW VARIABLES LIKE '%size%';
     SHOW GLOBAL VARIABLES LIKE '%size%';

Wildcard characters can be used in any position within the pattern to
be matched. Strictly speaking, because ``_'' is a wildcard that matches
any single character, you should escape it as ``\_'' to match it
literally. In practice, this is rarely necessary.


File: manual.info,  Node: show-warnings,  Prev: show-variables,  Up: show

12.5.6.40 `SHOW WARNINGS' Syntax
................................

     SHOW WARNINGS [LIMIT [OFFSET,] ROW_COUNT]
     SHOW COUNT(*) WARNINGS

*Note `SHOW WARNINGS': show-warnings. shows the error, warning, and
note messages that resulted from the last statement that generated
messages in the current session. It shows nothing if the last statement
used a table and generated no messages.  (That is, a statement that
uses a table but generates no messages clears the message list.)
Statements that do not use tables and do not generate messages have no
effect on the message list.

A related statement, *Note `SHOW ERRORS': show-errors, shows only the
errors. See *Note show-errors::.

The `SHOW COUNT(*) WARNINGS' statement displays the total number of
errors, warnings, and notes. You can also retrieve this number from the
`warning_count' variable:

     SHOW COUNT(*) WARNINGS;
     SELECT @@warning_count;

The value of `warning_count' might be greater than the number of
messages displayed by *Note `SHOW WARNINGS': show-warnings. if the
`max_error_count' system variable is set so low that not all messages
are stored. An example shown later in this section demonstrates how
this can happen.

The `LIMIT' clause has the same syntax as for the *Note `SELECT':
select. statement. See *Note select::.

The MySQL server sends back the total number of errors, warnings, and
notes resulting from the last statement. If you are using the C API,
this value can be obtained by calling *Note `mysql_warning_count()':
mysql-warning-count. See *Note mysql-warning-count::.

Warnings are generated for statements such as *Note `LOAD DATA INFILE':
load-data. and DML statements such as *Note `INSERT': insert, *Note
`UPDATE': update, *Note `CREATE TABLE': create-table, and *Note `ALTER
TABLE': alter-table.

The following *Note `DROP TABLE': drop-table.  statement results in a
note:

     mysql> DROP TABLE IF EXISTS no_such_table;
     mysql> SHOW WARNINGS;
     +-------+------+-------------------------------+
     | Level | Code | Message                       |
     +-------+------+-------------------------------+
     | Note  | 1051 | Unknown table 'no_such_table' |
     +-------+------+-------------------------------+

Here is a simple example that shows a syntax warning for *Note `CREATE
TABLE': create-table. and conversion warnings for *Note `INSERT':
insert.:

     mysql> CREATE TABLE t1 (a TINYINT NOT NULL, b CHAR(4)) TYPE=MyISAM;
     Query OK, 0 rows affected, 1 warning (0.00 sec)
     mysql> SHOW WARNINGS\G
     *************************** 1. row ***************************
       Level: Warning
        Code: 1287
     Message: 'TYPE=storage_engine' is deprecated, use
              'ENGINE=storage_engine' instead
     1 row in set (0.00 sec)

     mysql> INSERT INTO t1 VALUES(10,'mysql'),(NULL,'test'),
         -> (300,'Open Source');
     Query OK, 3 rows affected, 4 warnings (0.01 sec)
     Records: 3  Duplicates: 0  Warnings: 4

     mysql> SHOW WARNINGS\G
     *************************** 1. row ***************************
       Level: Warning
        Code: 1265
     Message: Data truncated for column 'b' at row 1
     *************************** 2. row ***************************
       Level: Warning
        Code: 1263
     Message: Data truncated, NULL supplied to NOT NULL column 'a' at row 2
     *************************** 3. row ***************************
       Level: Warning
        Code: 1264
     Message: Data truncated, out of range for column 'a' at row 3
     *************************** 4. row ***************************
       Level: Warning
        Code: 1265
     Message: Data truncated for column 'b' at row 3
     4 rows in set (0.00 sec)

The maximum number of error, warning, and note messages to store is
controlled by the `max_error_count' system variable. By default, its
value is 64. To change the number of messages you want stored, change
the value of `max_error_count'. In the following example, the *Note
`ALTER TABLE': alter-table. statement produces three warning messages,
but only one is stored because `max_error_count' has been set to 1:

     mysql> SHOW VARIABLES LIKE 'max_error_count';
     +-----------------+-------+
     | Variable_name   | Value |
     +-----------------+-------+
     | max_error_count | 64    |
     +-----------------+-------+
     1 row in set (0.00 sec)

     mysql> SET max_error_count=1;
     Query OK, 0 rows affected (0.00 sec)

     mysql> ALTER TABLE t1 MODIFY b CHAR;
     Query OK, 3 rows affected, 3 warnings (0.00 sec)
     Records: 3  Duplicates: 0  Warnings: 3

     mysql> SELECT @@warning_count;
     +-----------------+
     | @@warning_count |
     +-----------------+
     |               3 |
     +-----------------+
     1 row in set (0.01 sec)

     mysql> SHOW WARNINGS;
     +---------+------+----------------------------------------+
     | Level   | Code | Message                                |
     +---------+------+----------------------------------------+
     | Warning | 1263 | Data truncated for column 'b' at row 1 |
     +---------+------+----------------------------------------+
     1 row in set (0.00 sec)

To disable warnings, set `max_error_count' to 0. In this case,
`warning_count' still indicates how many warnings have occurred, but
none of the messages are stored.

You can set the `sql_notes' session variable to 0 to cause `Note'-level
warnings not to be recorded.


File: manual.info,  Node: other-administrative-sql,  Prev: show,  Up: sql-syntax-server-administration

12.5.7 Other Administrative Statements
--------------------------------------

* Menu:

* binlog::                       `BINLOG' Syntax
* cache-index::                  `CACHE INDEX' Syntax
* flush::                        `FLUSH' Syntax
* kill::                         `KILL' Syntax
* load-index::                   `LOAD INDEX INTO CACHE' Syntax
* reset::                        `RESET' Syntax


File: manual.info,  Node: binlog,  Next: cache-index,  Prev: other-administrative-sql,  Up: other-administrative-sql

12.5.7.1 `BINLOG' Syntax
........................

     BINLOG 'STR'

*Note `BINLOG': binlog. is an internal-use statement. It is generated
by the *Note `mysqlbinlog': mysqlbinlog.  program as the printable
representation of certain events in binary log files. (See *Note
mysqlbinlog::.) The `'STR'' value is a base 64-encoded string the that
server decodes to determine the data change indicated by the
corresponding event. This statement requires the `SUPER' privilege.


File: manual.info,  Node: cache-index,  Next: flush,  Prev: binlog,  Up: other-administrative-sql

12.5.7.2 `CACHE INDEX' Syntax
.............................

     CACHE INDEX
       TBL_INDEX_LIST [, TBL_INDEX_LIST] ...
       IN KEY_CACHE_NAME

     TBL_INDEX_LIST:
       TBL_NAME [[INDEX|KEY] (INDEX_NAME[, INDEX_NAME] ...)]

The *Note `CACHE INDEX': cache-index. statement assigns table indexes
to a specific key cache. It is used only for `MyISAM' tables.

The following statement assigns indexes from the tables `t1', `t2', and
`t3' to the key cache named `hot_cache':

     mysql> CACHE INDEX t1, t2, t3 IN hot_cache;
     +---------+--------------------+----------+----------+
     | Table   | Op                 | Msg_type | Msg_text |
     +---------+--------------------+----------+----------+
     | test.t1 | assign_to_keycache | status   | OK       |
     | test.t2 | assign_to_keycache | status   | OK       |
     | test.t3 | assign_to_keycache | status   | OK       |
     +---------+--------------------+----------+----------+

The syntax of *Note `CACHE INDEX': cache-index. enables you to specify
that only particular indexes from a table should be assigned to the
cache. The current implementation assigns all the table's indexes to
the cache, so there is no reason to specify anything other than the
table name.

The key cache referred to in a *Note `CACHE INDEX': cache-index.
statement can be created by setting its size with a parameter setting
statement or in the server parameter settings. For example:

     mysql> SET GLOBAL keycache1.key_buffer_size=128*1024;

Key cache parameters can be accessed as members of a structured system
variable. See *Note structured-system-variables::.

A key cache must exist before you can assign indexes to it:

     mysql> CACHE INDEX t1 IN non_existent_cache;
     ERROR 1284 (HY000): Unknown key cache 'non_existent_cache'

By default, table indexes are assigned to the main (default) key cache
created at the server startup. When a key cache is destroyed, all
indexes assigned to it become assigned to the default key cache again.

Index assignment affects the server globally: If one client assigns an
index to a given cache, this cache is used for all queries involving
the index, no matter which client issues the queries.


File: manual.info,  Node: flush,  Next: kill,  Prev: cache-index,  Up: other-administrative-sql

12.5.7.3 `FLUSH' Syntax
.......................

     FLUSH [NO_WRITE_TO_BINLOG | LOCAL]
         FLUSH_OPTION [, FLUSH_OPTION] ...

The *Note `FLUSH': flush. statement clears or reloads various internal
caches used by MySQL. To execute *Note `FLUSH': flush, you must have the
`RELOAD' privilege.

The *Note `RESET': reset. statement is similar to *Note `FLUSH': flush.
See *Note reset::.

FLUSH_OPTION can be any of the following:

   * `BACKUP LOGS'

     Closes and reopens the backup log files. This option was added in
     MySQL 6.0.8.

   * `DES_KEY_FILE'

     Reloads the DES keys from the file that was specified with the
     `--des-key-file' option at server startup time.

   * `HOSTS'

     Empties the host cache tables. You should flush the host tables if
     some of your hosts change IP number or if you get the error
     message `Host 'HOST_NAME' is blocked'.  When more than
     `max_connect_errors' errors occur successively for a given host
     while connecting to the MySQL server, MySQL assumes that something
     is wrong and blocks the host from further connection requests.
     Flushing the host tables enables further connection attempts from
     the host. See *Note blocked-host::. You can start *Note `mysqld':
     mysqld. with `--max_connect_errors=999999999' to avoid this error
     message.

   * `LOGS'

     Closes and reopens all log files. If binary logging is enabled,
     the sequence number of the binary log file is incremented by one
     relative to the previous file. On Unix, this is the same thing as
     sending a `SIGHUP' signal to the *Note `mysqld': mysqld. server
     (except on some Mac OS X 10.3 versions where *Note `mysqld':
     mysqld. ignores `SIGHUP' and `SIGQUIT').

     If the server is writing error output to a named file (for
     example, if it was started with the `--log-error' option), *Note
     `FLUSH LOGS': flush.  causes it to rename the current error log
     file with a suffix of `-old' and create a new empty log file.  No
     renaming occurs if the server is not writing to a named file (for
     example, if it is writing errors to the console).

   * `MASTER' (_DEPRECATED_).  Deletes all binary logs, resets the
     binary log index file and creates a new binary log.  *Note `FLUSH
     MASTER': flush. is deprecated in favor of *Note `RESET MASTER':
     reset-master, and is supported for backward compatibility only. See
     *Note reset-master::.

   * `PRIVILEGES'

     Reloads the privileges from the grant tables in the `mysql'
     database. On Unix, this also occurs if the server receives a
     `SIGHUP' signal.

     The server caches information in memory as a result of *Note
     `GRANT': grant, *Note `CREATE USER': create-user, *Note `CREATE
     SERVER': create-server, and *Note `INSTALL PLUGIN':
     install-plugin. statements.  This memory is not released by the
     corresponding *Note `REVOKE': revoke, *Note `DROP USER': drop-user,
     *Note `DROP SERVER': drop-server, and *Note `UNINSTALL PLUGIN':
     uninstall-plugin. statements, so for a server that executes many
     instances of the statements that cause caching, there will be an
     increase in memory use. This cached memory can be freed with *Note
     `FLUSH PRIVILEGES': flush.

   * `QUERY CACHE'

     Defragment the query cache to better utilize its memory.  *Note
     `FLUSH QUERY CACHE': flush. does not remove any queries from the
     cache, unlike *Note `FLUSH TABLES': flush. or `RESET QUERY CACHE'.

   * `SLAVE' (_DEPRECATED_).  Resets all replication slave parameters,
     including relay log files and replication position in the master's
     binary logs.  *Note `FLUSH SLAVE': flush.  is deprecated in favor
     of *Note `RESET SLAVE': reset-slave, and is supported for backward
     compatibility only. See *Note reset-slave::.

   * `STATUS'

     This option adds the current thread's session status variable
     values to the global values and resets the session values to zero.
     It also resets the counters for key caches (default and named) to
     zero and sets `Max_used_connections' to the current number of open
     connections. This is something you should use only when debugging
     a query. See *Note bug-reports::.

   * `{TABLE | TABLES} [TBL_NAME [, TBL_NAME] ...]'

     When no tables are named, closes all open tables, forces all
     tables in use to be closed, and flushes the query cache.  With one
     or more table names, flushes only the given tables.  *Note `FLUSH
     TABLES': flush. also removes all query results from the query
     cache, like the `RESET QUERY CACHE' statement. No error occurs if
     a named table does not exist.

   * `TABLES WITH READ LOCK'

     Closes all open tables and locks all tables for all databases with
     a read lock until you explicitly release the lock by executing
     *Note `UNLOCK TABLES': lock-tables. This is very convenient way to
     get backups if you have a file system such as Veritas that can take
     snapshots in time.

     *Note `FLUSH TABLES WITH READ LOCK': flush. acquires a global read
     lock and not table locks, so it is not subject to the same
     behavior as *Note `LOCK TABLES': lock-tables. and *Note `UNLOCK
     TABLES': lock-tables. with respect to table locking and implicit
     commits:

        * *Note `UNLOCK TABLES': lock-tables. implicitly commits any
          active transaction only if any tables currently have been
          locked with *Note `LOCK TABLES': lock-tables.  The commit
          does not occur for *Note `UNLOCK TABLES': lock-tables.
          following *Note `FLUSH TABLES WITH READ LOCK': flush. because
          the latter statement does not acquire table locks.

        * Beginning a transaction causes table locks acquired with
          *Note `LOCK TABLES': lock-tables. to be released, as though
          you had executed *Note `UNLOCK TABLES': lock-tables.
          Beginning a transaction does not release a global read lock
          acquired with *Note `FLUSH TABLES WITH READ LOCK': flush.

     *Note `FLUSH TABLES WITH READ LOCK': flush. does not prevent the
     server from inserting rows into the log tables (see *Note
     log-tables::).

     As of MySQL 6.0.11, *Note `FLUSH TABLES WITH READ LOCK': flush.
     blocks for active transactions that hold metadata locks until
     those transactions end.

   * `USER_RESOURCES'

     Resets all per-hour user resources to zero. This enables clients
     that have reached their hourly connection, query, or update limits
     to resume activity immediately.  *Note `FLUSH USER_RESOURCES':
     flush. does not apply to the limit on maximum simultaneous
     connections. See *Note grant::.

By default, *Note `FLUSH': flush. statements are written to the binary
log so that they will be replicated to replication slaves. Logging can
be suppressed with the optional `NO_WRITE_TO_BINLOG' keyword or its
alias `LOCAL'.

See also *Note reset::, for information about how the *Note `RESET':
reset. statement is used with replication.

*Note*:

*Note `FLUSH LOGS': flush, *Note `FLUSH MASTER': flush, *Note `FLUSH
SLAVE': flush, and *Note `FLUSH TABLES WITH READ LOCK': flush. are not
written to the binary log in any case because they would cause problems
if replicated to a slave.

The *Note `mysqladmin': mysqladmin. utility provides a command-line
interface to some flush operations, via the `flush-hosts', `flush-logs',
`flush-privileges', `flush-status', and `flush-tables' commands.

*Note*:

It is not possible in MySQL 6.0 to issue *Note `FLUSH': flush.
statements within stored functions or triggers. However, you may use
*Note `FLUSH': flush. in stored procedures, so long as these are not
called from stored functions or triggers. See *Note
stored-program-restrictions::.


File: manual.info,  Node: kill,  Next: load-index,  Prev: flush,  Up: other-administrative-sql

12.5.7.4 `KILL' Syntax
......................

     KILL [CONNECTION | QUERY] THREAD_ID

Each connection to *Note `mysqld': mysqld. runs in a separate thread.
You can see which threads are running with the *Note `SHOW
PROCESSLIST': show-processlist. statement and kill a thread with the
`KILL THREAD_ID' statement.

*Note `KILL': kill. allows the optional `CONNECTION' or `QUERY'
modifier:

   * *Note `KILL CONNECTION': kill. is the same as *Note `KILL': kill.
     with no modifier: It terminates the connection associated with the
     given THREAD_ID.

   * *Note `KILL QUERY': kill.  terminates the statement that the
     connection is currently executing, but leaves the connection
     itself intact.

If you have the `PROCESS' privilege, you can see all threads. If you
have the `SUPER' privilege, you can kill all threads and statements.
Otherwise, you can see and kill only your own threads and statements.

You can also use the *Note `mysqladmin processlist': mysqladmin.  and
*Note `mysqladmin kill': mysqladmin. commands to examine and kill
threads.

*Note*:

You cannot use *Note `KILL': kill. with the Embedded MySQL Server
library, because the embedded server merely runs inside the threads of
the host application. It does not create any connection threads of its
own.

When you use *Note `KILL': kill, a thread-specific kill flag is set for
the thread. In most cases, it might take some time for the thread to
die, because the kill flag is checked only at specific intervals:

   * In *Note `SELECT': select, `ORDER BY' and `GROUP BY' loops, the
     flag is checked after reading a block of rows. If the kill flag is
     set, the statement is aborted.

   * During *Note `ALTER TABLE': alter-table, the kill flag is checked
     before each block of rows are read from the original table. If the
     kill flag was set, the statement is aborted and the temporary
     table is deleted.

   * During *Note `UPDATE': update. or *Note `DELETE': delete.
     operations, the kill flag is checked after each block read and
     after each updated or deleted row. If the kill flag is set, the
     statement is aborted. Note that if you are not using transactions,
     the changes are not rolled back.

   * `GET_LOCK()' aborts and returns `NULL'.

   * An *Note `INSERT DELAYED': insert-delayed. thread quickly flushes
     (inserts) all rows it has in memory and then terminates.

   * If the thread is in the table lock handler (state: `Locked'), the
     table lock is quickly aborted.

   * If the thread is waiting for free disk space in a write call, the
     write is aborted with a `disk full' error message.

   * *Warning*:

     Killing a *Note `REPAIR TABLE': repair-table. or *Note `OPTIMIZE
     TABLE': optimize-table. operation on a `MyISAM' table results in a
     table that is corrupted and unusable. Any reads or writes to such a
     table fail until you optimize or repair it again (without
     interruption).


File: manual.info,  Node: load-index,  Next: reset,  Prev: kill,  Up: other-administrative-sql

12.5.7.5 `LOAD INDEX INTO CACHE' Syntax
.......................................

     LOAD INDEX INTO CACHE
       TBL_INDEX_LIST [, TBL_INDEX_LIST] ...

     TBL_INDEX_LIST:
       TBL_NAME
         [[INDEX|KEY] (INDEX_NAME[, INDEX_NAME] ...)]
         [IGNORE LEAVES]

The *Note `LOAD INDEX INTO CACHE': load-index. statement preloads a
table index into the key cache to which it has been assigned by an
explicit *Note `CACHE INDEX': cache-index. statement, or into the
default key cache otherwise.  *Note `LOAD INDEX INTO CACHE':
load-index. is used only for `MyISAM' tables. It is not supported for
tables having user-defined partitioning (see *Note
partitioning-limitations::.)

The `IGNORE LEAVES' modifier causes only blocks for the non-leaf nodes
of the index to be preloaded.

The following statement preloads nodes (index blocks) of indexes for
the tables `t1' and `t2':

     mysql> LOAD INDEX INTO CACHE t1, t2 IGNORE LEAVES;
     +---------+--------------+----------+----------+
     | Table   | Op           | Msg_type | Msg_text |
     +---------+--------------+----------+----------+
     | test.t1 | preload_keys | status   | OK       |
     | test.t2 | preload_keys | status   | OK       |
     +---------+--------------+----------+----------+

This statement preloads all index blocks from `t1'. It preloads only
blocks for the non-leaf nodes from `t2'.

The syntax of *Note `LOAD INDEX INTO CACHE': load-index. enables you to
specify that only particular indexes from a table should be preloaded.
The current implementation preloads all the table's indexes into the
cache, so there is no reason to specify anything other than the table
name.

`LOAD INDEX INTO CACHE ... IGNORE LEAVES' fails unless all indexes in a
table have the same block size. You can determine index block sizes for
a table by using *Note `myisamchk -dv': myisamchk. and checking the
`Blocksize' column.


File: manual.info,  Node: reset,  Prev: load-index,  Up: other-administrative-sql

12.5.7.6 `RESET' Syntax
.......................

     RESET RESET_OPTION [, RESET_OPTION] ...

The *Note `RESET': reset. statement is used to clear the state of
various server operations. You must have the `RELOAD' privilege to
execute *Note `RESET': reset.

*Note `RESET': reset. acts as a stronger version of the *Note `FLUSH':
flush. statement. See *Note flush::.

RESET_OPTION can be any of the following:

   * `MASTER'

     Deletes all binary logs listed in the index file, resets the
     binary log index file to be empty, and creates a new binary log
     file.

   * `QUERY CACHE'

     Removes all query results from the query cache.

   * `SLAVE'

     Makes the slave forget its replication position in the master
     binary logs. Also resets the relay log by deleting any existing
     relay log files and beginning a new one.


File: manual.info,  Node: sql-syntax-replication,  Next: sql-syntax-prepared-statements,  Prev: sql-syntax-server-administration,  Up: sql-syntax

12.6 Replication Statements
===========================

* Menu:

* replication-master-sql::       SQL Statements for Controlling Master Servers
* replication-slave-sql::        SQL Statements for Controlling Slave Servers

This section describes SQL statements related to replication. One group
of statements is used for controlling master servers. The other is used
for controlling slave servers.


File: manual.info,  Node: replication-master-sql,  Next: replication-slave-sql,  Prev: sql-syntax-replication,  Up: sql-syntax-replication

12.6.1 SQL Statements for Controlling Master Servers
----------------------------------------------------

* Menu:

* purge-binary-logs::            `PURGE BINARY LOGS' Syntax
* reset-master::                 `RESET MASTER' Syntax
* set-sql-log-bin::              `SET sql_log_bin' Syntax

Replication can be controlled through the SQL interface. This section
discusses statements for managing master replication servers. *Note
replication-slave-sql::, discusses statements for managing slave
servers.

The following *Note `SHOW': show. statements are used with master
servers in replication:

   * *Note `SHOW BINARY LOGS': show-binary-logs.

   * *Note `SHOW BINLOG EVENTS': show-binlog-events.

   * *Note `SHOW MASTER STATUS': show-master-status.

   * *Note `SHOW SLAVE HOSTS': show-slave-hosts.

For information about these statements, see *Note show::.


File: manual.info,  Node: purge-binary-logs,  Next: reset-master,  Prev: replication-master-sql,  Up: replication-master-sql

12.6.1.1 `PURGE BINARY LOGS' Syntax
...................................

     PURGE { BINARY | MASTER } LOGS
         { TO 'LOG_NAME' | BEFORE DATETIME_EXPR }

The binary log is a set of files that contain information about data
modifications made by the MySQL server. The log consists of a set of
binary log files, plus an index file.

The *Note `PURGE BINARY LOGS': purge-binary-logs. statement deletes all
the binary log files listed in the log index file prior to the
specified log file name or date. The log files also are removed from
the list recorded in the index file, so that the given log file becomes
the first.

This statement has no effect if the `--log-bin' option has not been
enabled.

Examples:

     PURGE BINARY LOGS TO 'mysql-bin.010';
     PURGE BINARY LOGS BEFORE '2008-04-02 22:46:26';

The `BEFORE' variant's DATETIME_EXPR argument should evaluate to a
*Note `DATETIME': datetime. value (a value in `'YYYY-MM-DD hh:mm:ss''
format).  `BINARY' and `MASTER' are synonyms.

This statement is safe to run while slaves are replicating. You do not
need to stop them. If you have an active slave that currently is
reading one of the logs you are trying to delete, this statement does
nothing and fails with an error. However, if a slave is dormant and you
happen to purge one of the logs it has yet to read, the slave will be
unable to replicate after it comes up.

To safely purge logs, follow this procedure:

  1. On each slave server, use *Note `SHOW SLAVE STATUS':
     show-slave-status. to check which log it is reading.

  2. Obtain a listing of the binary logs on the master server with
     *Note `SHOW BINARY LOGS': show-binary-logs.

  3. Determine the earliest log among all the slaves. This is the
     target log. If all the slaves are up to date, this is the last log
     on the list.

  4. Make a backup of all the logs you are about to delete. (This step
     is optional, but always advisable.)

  5. Purge all logs up to but not including the target log.

You can also set the `expire_logs_days' system variable to expire
binary log files automatically after a given number of days (see *Note
server-system-variables::).  If you are using replication, you should
set the variable no lower than the maximum number of days your slaves
might lag behind the master.

Prior to MySQL 6.0.5, `PURGE BINARY LOGS TO' and `PURGE BINARY LOGS
BEFORE' did not behave in the same way (and neither one behaved
correctly) when binary log files listed in the `.index' file had been
removed from the system by some other means (such as using rm on
Linux). Beginning with MySQL 6.0.5, both variants of the statement fail
with an error in such cases. (Bug#18199 (http://bugs.mysql.com/18199),
Bug#18453 (http://bugs.mysql.com/18453)) You can handle such errors by
editing the `.index' file (which is a simple text file) manually and
insuring that it lists only the binary log files that are actually
present, then running again the *Note `PURGE BINARY LOGS':
purge-binary-logs. statement that failed.


File: manual.info,  Node: reset-master,  Next: set-sql-log-bin,  Prev: purge-binary-logs,  Up: replication-master-sql

12.6.1.2 `RESET MASTER' Syntax
..............................

     RESET MASTER

Deletes all binary logs listed in the index file, resets the binary log
index file to be empty, and creates a new binary log file. It is
intended to be used only when the master is started for the first time.

*Important*:

This effects of this statement differ from those of *Note `PURGE BINARY
LOGS': purge-binary-logs. in 2 key ways:

  1. *Note `RESET MASTER': reset-master. removes _all_ binary logs that
     are listed in the index file, leaving only a single, empty binary
     log file named master-bin.000001, whereas the numbering is not
     reset by *Note `PURGE BINARY LOGS': purge-binary-logs.

  2. *Note `RESET MASTER': reset-master. is _not_ intended to be used
     while any replication slaves are running. The behavior of *Note
     `RESET MASTER': reset-master. when used while slaves are running
     is undefined (and thus unsupported), whereas *Note `PURGE BINARY
     LOGS': purge-binary-logs. may be safely used while replication
     slaves are running.

See also *Note purge-binary-logs::.

*Note `RESET MASTER': reset-master. can prove useful when you first set
up the master and the slave, so that you can verify the setup as
follows:

  1. Start the master and slave, and start replication (see *Note
     replication-howto::)

  2. Execute a few test queries on the master

  3. Check that the queries were replicated to the slave

  4. When replication is running correctly, issue *Note `STOP SLAVE':
     stop-slave. on the slave, followed by *Note `RESET SLAVE':
     reset-slave.; verify that any unwanted data no longer exists on
     the slave

  5. Issue *Note `RESET MASTER': reset-master. on the master to clean
     up the test queries

After verifying the setup and getting rid of any unwanted and logs
generated by testing, you can start the slave and begin replicating.


File: manual.info,  Node: set-sql-log-bin,  Prev: reset-master,  Up: replication-master-sql

12.6.1.3 `SET sql_log_bin' Syntax
.................................

     SET sql_log_bin = {0|1}

Disables or enables binary logging for the current connection
(`sql_log_bin' is a session variable) if the client has the `SUPER'
privilege. The statement is refused with an error if the client does
not have that privilege.


File: manual.info,  Node: replication-slave-sql,  Prev: replication-master-sql,  Up: sql-syntax-replication

12.6.2 SQL Statements for Controlling Slave Servers
---------------------------------------------------

* Menu:

* change-master-to::             `CHANGE MASTER TO' Syntax
* master-pos-wait::              `MASTER_POS_WAIT()' Syntax
* reset-slave::                  `RESET SLAVE' Syntax
* set-global-sql-slave-skip-counter::  `SET GLOBAL SQL_SLAVE_SKIP_COUNTER' Syntax
* start-slave::                  `START SLAVE' Syntax
* stop-slave::                   `STOP SLAVE' Syntax

Replication can be controlled through the SQL interface. This section
discusses statements for managing slave replication servers. *Note
replication-master-sql::, discusses statements for managing master
servers.

*Note `SHOW SLAVE STATUS': show-slave-status. is also used with
replication slaves. For information about this statement, see *Note
show-slave-status::.


File: manual.info,  Node: change-master-to,  Next: master-pos-wait,  Prev: replication-slave-sql,  Up: replication-slave-sql

12.6.2.1 `CHANGE MASTER TO' Syntax
..................................

     CHANGE MASTER TO MASTER_DEF [, MASTER_DEF] ...

     MASTER_DEF:
         MASTER_HOST = 'HOST_NAME'
       | MASTER_USER = 'USER_NAME'
       | MASTER_PASSWORD = 'PASSWORD'
       | MASTER_PORT = PORT_NUM
       | MASTER_CONNECT_RETRY = INTERVAL
       | MASTER_HEARTBEAT_PERIOD = INTERVAL
       | MASTER_LOG_FILE = 'MASTER_LOG_NAME'
       | MASTER_LOG_POS = MASTER_LOG_POS
       | RELAY_LOG_FILE = 'RELAY_LOG_NAME'
       | RELAY_LOG_POS = RELAY_LOG_POS
       | MASTER_SSL = {0|1}
       | MASTER_SSL_CA = 'CA_FILE_NAME'
       | MASTER_SSL_CAPATH = 'CA_DIRECTORY_NAME'
       | MASTER_SSL_CERT = 'CERT_FILE_NAME'
       | MASTER_SSL_KEY = 'KEY_FILE_NAME'
       | MASTER_SSL_CIPHER = 'CIPHER_LIST'
       | MASTER_SSL_VERIFY_SERVER_CERT = {0|1}
       | IGNORE_SERVER_IDS = (SERVER_ID_LIST)

     SERVER_ID_LIST:
         [SERVER_ID_1[, SERVER_ID_2[ ... ]]]

*Note `CHANGE MASTER TO': change-master-to. changes the parameters that
the slave server uses for connecting to and communicating with the
master server. It also updates the contents of the `master.info' and
`relay-log.info' files.

`MASTER_USER', `MASTER_PASSWORD', `MASTER_SSL', `MASTER_SSL_CA',
`MASTER_SSL_CAPATH', `MASTER_SSL_CERT', `MASTER_SSL_KEY',
`MASTER_SSL_CIPHER', and `MASTER_SSL_VERIFY_SERVER_CERT' provide
information to the slave about how to connect to its master. See *Note
ssl-options::.

`MASTER_CONNECT_RETRY' specifies how many seconds to wait between
connect retries. The default is 60. The _number_ of reconnection
attempts is limited by the `--master-retry-count' server option; for
more information, see *Note replication-options::.

The SSL options (`MASTER_SSL', `MASTER_SSL_CA', `MASTER_SSL_CAPATH',
`MASTER_SSL_CERT', `MASTER_SSL_KEY', `MASTER_SSL_CIPHER'), and
`MASTER_SSL_VERIFY_SERVER_CERT' can be changed even on slaves that are
compiled without SSL support. They are saved to the `master.info' file,
but are ignored unless you use a server that has SSL support enabled.

If you don't specify a given parameter, it keeps its old value, except
as indicated in the following discussion. For example, if the password
to connect to your MySQL master has changed, you just need to issue
these statements to tell the slave about the new password:

     STOP SLAVE; -- if replication was running
     CHANGE MASTER TO MASTER_PASSWORD='new3cret';
     START SLAVE; -- if you want to restart replication

There is no need to specify the parameters that do not change (host,
port, user, and so forth).

`MASTER_HOST' and `MASTER_PORT' are the host name (or IP address) of
the master host and its TCP/IP port.

`MASTER_HEARTBEAT_PERIOD' is used to set the interval in seconds
between replication heartbeats. Whenever the master's binlog is updated
with an event, the waiting period for the next heartbeat is reset.
INTERVAL is a decimal value having the range 0 to 4294967 seconds and a
resolution to hundredths of a second; the smallest nonzero value is
0.001. Heartbeats are sent by the master only if there are no unsent
events in the binlog file for a period longer than INTERVAL.

`MASTER_HEARTBEAT_PERIOD' was added in MySQL 6.0.4.

Setting INTERVAL to 0 disables heartbeats altogether. The default value
for INTERVAL is equal to the value of `slave_net_timeout'
(http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_net_timeout)
divided by 2.

*Note*:

Setting `@@global.slave_net_timeout' to a value less than that of the
current heartbeat interval results in a warning being issued.

Issuing *Note `RESET SLAVE': reset-slave. resets the heartbeat interval
to the default.

*Note*:

Replication cannot use Unix socket files. You must be able to connect
to the master MySQL server using TCP/IP.

If you specify `MASTER_HOST' or `MASTER_PORT', the slave assumes that
the master server is different from before (even if you specify a host
or port value that is the same as the current value.) In this case, the
old values for the master binary log name and position are considered
no longer applicable, so if you do not specify `MASTER_LOG_FILE' and
`MASTER_LOG_POS' in the statement, `MASTER_LOG_FILE=''' and
`MASTER_LOG_POS=4' are silently appended to it.

Setting `MASTER_HOST=''' -- that is, setting its value explicitly to an
empty string -- is _not_ the same as not setting `MASTER_HOST' at all.
Previously, setting `MASTER_HOST' to an empty string caused *Note
`START SLAVE': start-slave. subsequently to fail.  Beginning with MySQL
6.0.11, trying to set `MASTER_HOST' to an empty string fails with an
error. (Bug#28796 (http://bugs.mysql.com/28796))

`MASTER_LOG_FILE' and `MASTER_LOG_POS' are the coordinates at which the
slave I/O thread should begin reading from the master the next time the
thread starts. If you specify either of them, you cannot specify
`RELAY_LOG_FILE' or `RELAY_LOG_POS'. If neither of `MASTER_LOG_FILE' or
`MASTER_LOG_POS' are specified, the slave uses the last coordinates of
the _slave SQL thread_ before *Note `CHANGE MASTER TO':
change-master-to. was issued. This ensures that there is no
discontinuity in replication, even if the slave SQL thread was late
compared to the slave I/O thread, when you merely want to change, say,
the password to use.

`IGNORE_SERVER_IDS' was added in MySQL 6.0.10.  This option takes a
comma-separated list of 0 or more server IDs; events from the
corresponding servers are ignored, with the exception of log rotation
and deletion events, which are still recorded in the relay log.

In circular replication, the originating server normally acts as the
terminator of its own events, so that they are not applied more than
once. Thus, this option is useful in circular replication when one of
the servers in the circle is removed.  For example, suppose that you
have a circular replication setup with 4 servers, having server IDs 1,
2, 3, and 4, and server 3 fails. When bridging the gap by starting
replication from server 2 to server 4, you can include
`IGNORE_SERVER_IDS = (3)' in the `CHANGE MASTER TO' statement that you
issue on server 4 to tell it to use server 2 as its master instead of
server 3. Doing so causes it to ignore and not to propagate any
statements that originated with the server that is no longer in use.

If a `CHANGE MASTER TO' statement is issued without any
`IGNORE_SERVER_IDS' option, any existing list is preserved; *Note
`RESET SLAVE': reset-slave. also has no effect on the server ID list. To
clear the list of servers that are ignored, it is necessary to use the
option with an empty list (that is, as `IGNORE_SERVER_IDS = ()').

If `IGNORE_SERVER_IDS' contains the server's own ID and the server was
started with the `--replicate-same-server-id' option enabled, an error
results.

Also beginning with MySQL 6.0.10, the `master.info' file and the output
of `SHOW SLAVE STATUS' are extended to provide the list of servers that
are currently ignored. For more information, see *Note
slave-logs-status::, and *Note show-slave-status::.

*Note `CHANGE MASTER TO': change-master-to.  _deletes all relay log
files_ and starts a new one, unless you specify `RELAY_LOG_FILE' or
`RELAY_LOG_POS'. In that case, relay logs are kept; the
`relay_log_purge' global variable is set silently to 0.

*Note `CHANGE MASTER TO': change-master-to. is useful for setting up a
slave when you have the snapshot of the master and have recorded the
log and the offset corresponding to it. After loading the snapshot into
the slave, you can run `CHANGE MASTER TO
MASTER_LOG_FILE='LOG_NAME_ON_MASTER',
MASTER_LOG_POS=LOG_OFFSET_ON_MASTER' on the slave.

The following example changes the master and master's binary log
coordinates. This is used when you want to set up the slave to
replicate the master:

     CHANGE MASTER TO
       MASTER_HOST='master2.mycompany.com',
       MASTER_USER='replication',
       MASTER_PASSWORD='bigs3cret',
       MASTER_PORT=3306,
       MASTER_LOG_FILE='master2-bin.001',
       MASTER_LOG_POS=4,
       MASTER_CONNECT_RETRY=10;

The next example shows an operation that is less frequently employed.
It is used when the slave has relay logs that you want it to execute
again for some reason. To do this, the master need not be reachable.
You need only use *Note `CHANGE MASTER TO': change-master-to. and start
the SQL thread (`START SLAVE SQL_THREAD'):

     CHANGE MASTER TO
       RELAY_LOG_FILE='slave-relay-bin.006',
       RELAY_LOG_POS=4025;

You can even use the second operation in a non-replication setup with a
standalone, non-slave server for recovery following a crash. Suppose
that your server has crashed and you have restored a backup. You want
to replay the server's own binary logs (not relay logs, but regular
binary logs), named (for example) `myhost-bin.*'. First, make a backup
copy of these binary logs in some safe place, in case you don't exactly
follow the procedure below and accidentally have the server purge the
binary logs. Use `SET GLOBAL relay_log_purge=0' for additional safety.
Then start the server without the `--log-bin' option, Instead, use the
`--replicate-same-server-id', `--relay-log=myhost-bin' (to make the
server believe that these regular binary logs are relay logs) and
`--skip-slave-start' options. After the server starts, issue these
statements:

     CHANGE MASTER TO
       RELAY_LOG_FILE='myhost-bin.153',
       RELAY_LOG_POS=410,
       MASTER_HOST='some_dummy_string';
     START SLAVE SQL_THREAD;

The server reads and executes its own binary logs, thus achieving crash
recovery. Once the recovery is finished, run *Note `STOP SLAVE':
stop-slave, shut down the server, delete the `master.info' and
`relay-log.info' files, and restart the server with its original
options.

Specifying the `MASTER_HOST' option (even with a dummy value) is
required to make the server think it is a slave.


File: manual.info,  Node: master-pos-wait,  Next: reset-slave,  Prev: change-master-to,  Up: replication-slave-sql

12.6.2.2 `MASTER_POS_WAIT()' Syntax
...................................

     SELECT MASTER_POS_WAIT('MASTER_LOG_FILE', MASTER_LOG_POS [, TIMEOUT])

This is actually a function, not a statement. It is used to ensure that
the slave has read and executed events up to a given position in the
master's binary log. See *Note miscellaneous-functions::, for a full
description.


File: manual.info,  Node: reset-slave,  Next: set-global-sql-slave-skip-counter,  Prev: master-pos-wait,  Up: replication-slave-sql

12.6.2.3 `RESET SLAVE' Syntax
.............................

     RESET SLAVE

*Note `RESET SLAVE': reset-slave. makes the slave forget its
replication position in the master's binary logs.  This statement is
meant to be used for a clean start: It deletes the `master.info' and
`relay-log.info' files, all the relay logs, and starts a new relay log.

*Note*:

All relay logs are deleted, even if they have not been completely
executed by the slave SQL thread. (This is a condition likely to exist
on a replication slave if you have issued a *Note `STOP SLAVE':
stop-slave. statement or if the slave is highly loaded.)

In MySQL 6.0 -- unlike the case in MySQL 5.1 and earlier -- `RESET
SLAVE' no longer changes replication connection parameters such as
master host, master port, master user, and master password. (This means
that *Note `START SLAVE': start-slave. can be issued without requiring
a *Note `CHANGE MASTER TO': change-master-to.  statement following
`RESET SLAVE'.) However, connection parameters (which are now retained
in memory even after `RESET SLAVE' is issued) are reset if the slave is
shut down.

If the slave SQL thread was in the middle of replicating temporary
tables when it was stopped, and `RESET SLAVE' is issued, these
replicated temporary tables are deleted on the slave.


File: manual.info,  Node: set-global-sql-slave-skip-counter,  Next: start-slave,  Prev: reset-slave,  Up: replication-slave-sql

12.6.2.4 `SET GLOBAL SQL_SLAVE_SKIP_COUNTER' Syntax
...................................................

     SET GLOBAL SQL_SLAVE_SKIP_COUNTER = N

This statement skips the next N events from the master. This is useful
for recovering from replication stops caused by a statement.

This statement is valid only when the slave thread is not running.
Otherwise, it produces an error.

When using this statement, it is important to understand that the
binary log is actually organized as a sequence of groups known as
_event groups_. Each event group consists of a sequence of events.

   * For transactional tables, an event group corresponds to a
     transaction.

   * For non-transactional tables, an event group corresponds to a
     single SQL statement.

*Note*:

A single transaction can contain changes to both transactional and
non-transactional tables.

When you use `SET GLOBAL SQL_SLAVE_SKIP_COUNTER' to skip events and the
result is in the middle of a group, the slave continues to skip events
until it reaches the end of the group. Execution then starts with the
next event group.


File: manual.info,  Node: start-slave,  Next: stop-slave,  Prev: set-global-sql-slave-skip-counter,  Up: replication-slave-sql

12.6.2.5 `START SLAVE' Syntax
.............................

     START SLAVE [THREAD_TYPE [, THREAD_TYPE] ... ]
     START SLAVE [SQL_THREAD] UNTIL
         MASTER_LOG_FILE = 'LOG_NAME', MASTER_LOG_POS = LOG_POS
     START SLAVE [SQL_THREAD] UNTIL
         RELAY_LOG_FILE = 'LOG_NAME', RELAY_LOG_POS = LOG_POS

     THREAD_TYPE: IO_THREAD | SQL_THREAD

*Note `START SLAVE': start-slave. with no THREAD_TYPE options starts
both of the slave threads. The I/O thread reads queries from the master
server and stores them in the relay log. The SQL thread reads the relay
log and executes the queries.  *Note `START SLAVE': start-slave.
requires the `SUPER' privilege.

If *Note `START SLAVE': start-slave. succeeds in starting the slave
threads, it returns without any error.  However, even in that case, it
might be that the slave threads start and then later stop (for example,
because they do not manage to connect to the master or read its binary
logs, or some other problem). *Note `START SLAVE': start-slave. does
not warn you about this. You must check the slave's error log for error
messages generated by the slave threads, or check that they are running
satisfactorily with *Note `SHOW SLAVE STATUS': show-slave-status.

*Note `START SLAVE': start-slave. sends an acknowledgement to the user
after both the IO thread and the SQL thread have started. However, the
IO thread may not yet have connected. For this reason, a successful
*Note `START SLAVE': start-slave. causes *Note `SHOW SLAVE STATUS':
show-slave-status. to show `Slave_SQL_Running=Yes', but this does not
guarantee that `Slave_IO_Running=Yes' (because `Slave_IO_Running=Yes'
only if the IO thread is running _and connected_). For more
information, see *Note show-slave-status::, and *Note
replication-administration-status::.

You can add `IO_THREAD' and `SQL_THREAD' options to the statement to
name which of the threads to start.

An `UNTIL' clause may be added to specify that the slave should start
and run until the SQL thread reaches a given point in the master binary
logs or in the slave relay logs. When the SQL thread reaches that
point, it stops. If the `SQL_THREAD' option is specified in the
statement, it starts only the SQL thread. Otherwise, it starts both
slave threads. If the SQL thread is running, the `UNTIL' clause is
ignored and a warning is issued.

For an `UNTIL' clause, you must specify both a log file name and
position. Do not mix master and relay log options.

Any `UNTIL' condition is reset by a subsequent *Note `STOP SLAVE':
stop-slave. statement, a *Note `START SLAVE': start-slave. statement
that includes no `UNTIL' clause, or a server restart.

The `UNTIL' clause can be useful for debugging replication, or to cause
replication to proceed until just before the point where you want to
avoid having the slave replicate a statement. For example, if an unwise
*Note `DROP TABLE': drop-table. statement was executed on the master,
you can use `UNTIL' to tell the slave to execute up to that point but
no farther. To find what the event is, use *Note `mysqlbinlog':
mysqlbinlog. with the master logs or slave relay logs, or by using a
*Note `SHOW BINLOG EVENTS': show-binlog-events. statement.

If you are using `UNTIL' to have the slave process replicated queries
in sections, it is recommended that you start the slave with the
`--skip-slave-start' option to prevent the SQL thread from running when
the slave server starts. It is probably best to use this option in an
option file rather than on the command line, so that an unexpected
server restart does not cause it to be forgotten.

The *Note `SHOW SLAVE STATUS': show-slave-status. statement includes
output fields that display the current values of the `UNTIL' condition.

In old versions of MySQL (before 4.0.5), this statement was called
`SLAVE START'. This usage is still accepted in MySQL 6.0 for backward
compatibility, but is deprecated.


File: manual.info,  Node: stop-slave,  Prev: start-slave,  Up: replication-slave-sql

12.6.2.6 `STOP SLAVE' Syntax
............................

     STOP SLAVE [THREAD_TYPE [, THREAD_TYPE] ... ]

     THREAD_TYPE: IO_THREAD | SQL_THREAD

Stops the slave threads. *Note `STOP SLAVE': stop-slave. requires the
`SUPER' privilege.

Like *Note `START SLAVE': start-slave, this statement may be used with
the `IO_THREAD' and `SQL_THREAD' options to name the thread or threads
to be stopped.

In old versions of MySQL (before 4.0.5), this statement was called
`SLAVE STOP'. This usage is still accepted in MySQL 6.0 for backward
compatibility, but is deprecated.


File: manual.info,  Node: sql-syntax-prepared-statements,  Next: sql-syntax-compound-statements,  Prev: sql-syntax-replication,  Up: sql-syntax

12.7 SQL Syntax for Prepared Statements
=======================================

* Menu:

* prepare::                      `PREPARE' Syntax
* execute::                      `EXECUTE' Syntax
* deallocate-prepare::           `DEALLOCATE PREPARE' Syntax
* statement-repreparation::      Automatic Prepared Statement Repreparation

MySQL 6.0 provides support for server-side prepared statements. This
support takes advantage of the efficient client/server binary protocol
implemented in MySQL 4.1, provided that you use an appropriate client
programming interface. Candidate interfaces include the MySQL C API
client library (for C programs), MySQL Connector/J (for Java programs),
and MySQL Connector/NET. For example, the C API provides a set of
function calls that make up its prepared statement API. See *Note
c-api-prepared-statements::. Other language interfaces can provide
support for prepared statements that use the binary protocol by linking
in the C client library, one example being the `mysqli' extension
(http://php.net/mysqli), available in PHP 5.0 and later.

An alternative SQL interface to prepared statements is available.  This
interface is not as efficient as using the binary protocol through a
prepared statement API, but requires no programming because it is
available directly at the SQL level:

   * You can use it when no programming interface is available to you.

   * You can use it from any program that allows you to send SQL
     statements to the server to be executed, such as the *Note
     `mysql': mysql. client program.

   * You can use it even if the client is using an old version of the
     client library. The only requirement is that you be able to
     connect to a server that is recent enough to support SQL syntax
     for prepared statements.

SQL syntax for prepared statements is intended to be used for
situations such as these:

   * You want to test how prepared statements work in your application
     before coding it.

   * An application has problems executing prepared statements and you
     want to determine interactively what the problem is.

   * You want to create a test case that describes a problem you are
     having with prepared statements, so that you can file a bug report.

   * You need to use prepared statements but do not have access to a
     programming API that supports them.

SQL syntax for prepared statements is based on three SQL statements:

   * *Note `PREPARE': prepare. prepares a statement for execution (see
     *Note prepare::).

   * *Note `EXECUTE': execute. executes a prepared statement (see *Note
     execute::).

   * *Note `DEALLOCATE PREPARE': deallocate-prepare. releases a
     prepared statement (see *Note deallocate-prepare::).

The following examples show two equivalent ways of preparing a
statement that computes the hypotenuse of a triangle given the lengths
of the two sides.

The first example shows how to create a prepared statement by using a
string literal to supply the text of the statement:

     mysql> PREPARE stmt1 FROM 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse';
     mysql> SET @a = 3;
     mysql> SET @b = 4;
     mysql> EXECUTE stmt1 USING @a, @b;
     +------------+
     | hypotenuse |
     +------------+
     |          5 |
     +------------+
     mysql> DEALLOCATE PREPARE stmt1;

The second example is similar, but supplies the text of the statement
as a user variable:

     mysql> SET @s = 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse';
     mysql> PREPARE stmt2 FROM @s;
     mysql> SET @a = 6;
     mysql> SET @b = 8;
     mysql> EXECUTE stmt2 USING @a, @b;
     +------------+
     | hypotenuse |
     +------------+
     |         10 |
     +------------+
     mysql> DEALLOCATE PREPARE stmt2;

Here is an additional example which demonstrates how to choose the
table on which to perform a query at run time, by storing the name of
the table as a user variable:

     mysql> USE test;
     mysql> CREATE TABLE t1 (a INT NOT NULL);
     mysql> INSERT INTO t1 VALUES (4), (8), (11), (32), (80);

     mysql> SET @table = 't1';
     mysql> SET @s = CONCAT('SELECT * FROM ', @table);

     mysql> PREPARE stmt3 FROM @s;
     mysql> EXECUTE stmt3;
     +----+
     | a  |
     +----+
     |  4 |
     |  8 |
     | 11 |
     | 32 |
     | 80 |
     +----+

     mysql> DEALLOCATE PREPARE stmt3;

A prepared statement is specific to the session in which it was
created. If you terminate a session without deallocating a previously
prepared statement, the server deallocates it automatically.

A prepared statement is also global to the session. If you create a
prepared statement within a stored routine, it is not deallocated when
the stored routine ends.

To guard against too many prepared statements being created
simultaneously, set the `max_prepared_stmt_count' system variable. To
prevent the use of prepared statements, set the value to 0.

The following SQL statements can be used as prepared statements:

     ALTER TABLE
     ANALYZE TABLE
     CACHE INDEX
     CALL
     CHANGE MASTER
     CHECKSUM {TABLE | TABLES}
     COMMIT
     {CREATE | DROP} DATABASE
     {CREATE | RENAME | DROP} USER
     CREATE INDEX
     CREATE TABLE
     DELETE
     DO
     DROP INDEX
     DROP TABLE
     FLUSH {TABLE | TABLES | TABLES WITH READ LOCK | HOSTS | PRIVILEGES
       | LOGS | STATUS | MASTER | SLAVE | DES_KEY_FILE | USER_RESOURCES}
     GRANT
     INSERT
     INSTALL PLUGIN
     KILL
     LOAD INDEX INTO CACHE
     OPTIMIZE TABLE
     RENAME TABLE
     REPAIR TABLE
     REPLACE
     RESET {MASTER | SLAVE | QUERY CACHE}
     REVOKE
     SELECT
     SET
     SHOW BINLOG EVENTS
     SHOW CREATE {PROCEDURE | FUNCTION | EVENT | TABLE | VIEW}
     SHOW {AUTHORS | CONTRIBUTORS | WARNINGS | ERRORS}
     SHOW {MASTER | BINARY} LOGS
     SHOW {MASTER | SLAVE} STATUS
     SLAVE {START | STOP}
     UNINSTALL PLUGIN
     UPDATE

Other statements are not yet supported.

Statements not allowed in SQL prepared statements are generally also
not permitted in stored routines. Any exceptions to this rule are noted
in *Note stored-routines::.

Placeholders can be used for the arguments of the `LIMIT' clause when
using prepared statements. See *Note select::.

In prepared *Note `CALL': call. statements used with *Note `PREPARE':
prepare. and *Note `EXECUTE': execute, placeholder support for `OUT'
and `INOUT' parameters is not available until MySQL 6.0.8. See *Note
call::, for an example and a workaround for earlier versions.
Placeholders can be used for `IN' parameters regardless of version.

SQL syntax for prepared statements cannot be used in nested fashion.
That is, a statement passed to *Note `PREPARE': prepare. cannot itself
be a *Note `PREPARE': prepare, *Note `EXECUTE': execute, or *Note
`DEALLOCATE PREPARE': deallocate-prepare. statement.

SQL syntax for prepared statements is distinct from using prepared
statement API calls. For example, you cannot use the *Note
`mysql_stmt_prepare()': mysql-stmt-prepare. C API function to prepare a
*Note `PREPARE': prepare, *Note `EXECUTE': execute, or *Note
`DEALLOCATE PREPARE': deallocate-prepare. statement.

SQL syntax for prepared statements can be used within stored
procedures, but not in stored functions or triggers. However, a cursor
cannot be used for a dynamic statement that is prepared and executed
with *Note `PREPARE': prepare. and *Note `EXECUTE': execute. The
statement for a cursor is checked at cursor creation time, so the
statement cannot be dynamic.

SQL syntax for prepared statements does not support multi-statements
(that is, multiple statements within a single string separated by ``;''
characters).

Prepared statements use the query cache under the conditions described
in *Note query-cache-operation::.

To write C programs that use the *Note `CALL': call.  SQL statement to
execute stored procedures that contain prepared statements, the
`CLIENT_MULTI_RESULTS' flag must be enabled. This is because each *Note
`CALL': call.  returns a result to indicate the call status, in
addition to any result sets that might be returned by statements
executed within the procedure.

`CLIENT_MULTI_RESULTS' can be enabled when you call *Note
`mysql_real_connect()': mysql-real-connect, either explicitly by
passing the `CLIENT_MULTI_RESULTS' flag itself, or implicitly by passing
`CLIENT_MULTI_STATEMENTS' (which also enables `CLIENT_MULTI_RESULTS').
For additional information, see *Note call::.


File: manual.info,  Node: prepare,  Next: execute,  Prev: sql-syntax-prepared-statements,  Up: sql-syntax-prepared-statements

12.7.1 `PREPARE' Syntax
-----------------------

     PREPARE STMT_NAME FROM PREPARABLE_STMT

The *Note `PREPARE': prepare. statement prepares a statement and
assigns it a name, STMT_NAME, by which to refer to the statement later.
Statement names are not case sensitive.  PREPARABLE_STMT is either a
string literal or a user variable that contains the text of the
statement. The text must represent a single SQL statement, not multiple
statements. Within the statement, ``?'' characters can be used as
parameter markers to indicate where data values are to be bound to the
query later when you execute it. The ``?'' characters should not be
enclosed within quotes, even if you intend to bind them to string
values. Parameter markers can be used only where data values should
appear, not for SQL keywords, identifiers, and so forth.

If a prepared statement with the given name already exists, it is
deallocated implicitly before the new statement is prepared. This means
that if the new statement contains an error and cannot be prepared, an
error is returned and no statement with the given name exists.

A prepared statement is executed with *Note `EXECUTE': execute. and
released with *Note `DEALLOCATE PREPARE': deallocate-prepare.

The scope of a prepared statement is the session within which it is
created. Other sessions cannot see it.

For examples, see *Note sql-syntax-prepared-statements::.


File: manual.info,  Node: execute,  Next: deallocate-prepare,  Prev: prepare,  Up: sql-syntax-prepared-statements

12.7.2 `EXECUTE' Syntax
-----------------------

     EXECUTE STMT_NAME
         [USING @VAR_NAME [, @VAR_NAME] ...]

After preparing a statement with *Note `PREPARE': prepare, you execute
it with an *Note `EXECUTE': execute. statement that refers to the
prepared statement name. If the prepared statement contains any
parameter markers, you must supply a `USING' clause that lists user
variables containing the values to be bound to the parameters.
Parameter values can be supplied only by user variables, and the
`USING' clause must name exactly as many variables as the number of
parameter markers in the statement.

You can execute a given prepared statement multiple times, passing
different variables to it or setting the variables to different values
before each execution.

For examples, see *Note sql-syntax-prepared-statements::.


File: manual.info,  Node: deallocate-prepare,  Next: statement-repreparation,  Prev: execute,  Up: sql-syntax-prepared-statements

12.7.3 `DEALLOCATE PREPARE' Syntax
----------------------------------

     {DEALLOCATE | DROP} PREPARE STMT_NAME

To deallocate a prepared statement produced with *Note `PREPARE':
prepare, use a *Note `DEALLOCATE PREPARE': deallocate-prepare.
statement that refers to the prepared statement name. Attempting to
execute a prepared statement after deallocating it results in an error.

For examples, see *Note sql-syntax-prepared-statements::.


File: manual.info,  Node: statement-repreparation,  Prev: deallocate-prepare,  Up: sql-syntax-prepared-statements

12.7.4 Automatic Prepared Statement Repreparation
-------------------------------------------------

As of MySQL 6.0.6, metadata changes to tables or views referred to by
prepared statements are detected and cause automatic repreparation of
the statement when it is next executed. This applies to prepared
statements processed at the SQL level (using the *Note `PREPARE':
prepare. statement) and those processed using the binary client-server
protocol (using the *Note `mysql_stmt_prepare()': mysql-stmt-prepare. C
API function).

Metadata changes occur for DDL statements such as those that create,
drop, alter, rename, or truncate tables, or that analyze, optimize, or
repair tables. Repreparation also occurs after referenced tables or
views are flushed from the table definition cache, either implicitly to
make room for new entries in the cache, or explicitly due to *Note
`FLUSH TABLES': flush.

Repreparation is automatic, but to the extent that it occurs,
performance of prepared statements is diminished.

When a statement is reprepared, the default database and SQL mode that
were in effect for the original preparation are used.

Table content changes (for example, with *Note `INSERT': insert. or
*Note `UPDATE': update.) do not cause repreparation, nor do *Note
`SELECT': select. statements.

An incompatibility with previous versions of MySQL is that a prepared
statement may return a different set of columns or different column
types from one execution to the next. For example, if the prepared
statement is `SELECT * FROM t1', altering `t1' to contain a different
number of columns causes the next execution to return a number of
columns different from the previous execution.

Older versions of the client library cannot handle this change in
behavior. For applications that use prepared statements with a server
that performs automatic repreparation, an upgrade to the new client
library is strongly recommended.

The `Com_stmt_reprepare' status variable tracks the number of
repreparations.


File: manual.info,  Node: sql-syntax-compound-statements,  Prev: sql-syntax-prepared-statements,  Up: sql-syntax

12.8 MySQL Compound-Statement Syntax
====================================

* Menu:

* begin-end::                    `BEGIN ... END' Compound Statement Syntax
* declare::                      `DECLARE' Syntax
* variables-in-stored-programs::  Variables in Stored Programs
* conditions-and-handlers::      Conditions and Handlers
* cursors::                      Cursors
* flow-control-constructs::      Flow Control Constructs
* return::                       `RETURN' Syntax
* signal-resignal::              `SIGNAL' and `RESIGNAL'

This section describes the syntax for the `BEGIN ...  END' compound
statement and other statements that can be used in the body of stored
programs: Stored procedures and functions, triggers, and events. These
objects are defined in terms of SQL code that is stored on the server
for later invocation (see *Note stored-programs-views::).


File: manual.info,  Node: begin-end,  Next: declare,  Prev: sql-syntax-compound-statements,  Up: sql-syntax-compound-statements

12.8.1 `BEGIN ... END' Compound Statement Syntax
------------------------------------------------

     [BEGIN_LABEL:] BEGIN
         [STATEMENT_LIST]
     END [END_LABEL]

`BEGIN ... END' syntax is used for writing compound statements, which
can appear within stored programs. A compound statement can contain
multiple statements, enclosed by the `BEGIN' and `END' keywords.
STATEMENT_LIST represents a list of one or more statements, each
terminated by a semicolon (`;') statement delimiter.  STATEMENT_LIST is
optional, which means that the empty compound statement (`BEGIN END')
is legal.

Use of multiple statements requires that a client is able to send
statement strings containing the `;' statement delimiter. This is
handled in the *Note `mysql': mysql.  command-line client with the
`delimiter' command.  Changing the `;' end-of-statement delimiter (for
example, to `//') allows `;' to be used in a program body. For an
example, see *Note stored-programs-defining::.

A compound statement can be labeled.  END_LABEL cannot be given unless
BEGIN_LABEL also is present. If both are present, they must be the same.

The optional `[NOT] ATOMIC' clause is not supported. This means that no
transactional savepoint is set at the start of the instruction block
and the `BEGIN' clause used in this context has no effect on the
current transaction.


File: manual.info,  Node: declare,  Next: variables-in-stored-programs,  Prev: begin-end,  Up: sql-syntax-compound-statements

12.8.2 `DECLARE' Syntax
-----------------------

The *Note `DECLARE': declare. statement is used to define various items
local to a program:

   * Local variables. See *Note variables-in-stored-programs::.

   * Conditions and handlers. See *Note conditions-and-handlers::.

   * Cursors. See *Note cursors::.

*Note `DECLARE': declare. is allowed only inside a `BEGIN ... END'
compound statement and must be at its start, before any other
statements.

Declarations must follow a certain order. Cursors must be declared
before declaring handlers, and variables and conditions must be
declared before declaring either cursors or handlers.


File: manual.info,  Node: variables-in-stored-programs,  Next: conditions-and-handlers,  Prev: declare,  Up: sql-syntax-compound-statements

12.8.3 Variables in Stored Programs
-----------------------------------

* Menu:

* declare-local-variable::       `DECLARE' for Local Variables
* set-statement::                Variable `SET' Statement
* select-into-statement::        `SELECT ... INTO' Statement
* local-variable-scope::         Scope and Resolution of Local Variables

You may declare and use variables within stored programs.


File: manual.info,  Node: declare-local-variable,  Next: set-statement,  Prev: variables-in-stored-programs,  Up: variables-in-stored-programs

12.8.3.1 `DECLARE' for Local Variables
......................................

     DECLARE VAR_NAME [, VAR_NAME] ... TYPE [DEFAULT VALUE]

This statement is used to declare local variables within stored
programs. To provide a default value for the variable, include a
`DEFAULT' clause. The value can be specified as an expression; it need
not be a constant. If the `DEFAULT' clause is missing, the initial value
is `NULL'.

Local variables are treated like stored routine parameters with respect
to data type and overflow checking. See *Note create-procedure::.

Local variable names are not case sensitive.

The scope of a local variable is within the `BEGIN ...  END' block
where it is declared. The variable can be referred to in blocks nested
within the declaring block, except those blocks that declare a variable
with the same name.


File: manual.info,  Node: set-statement,  Next: select-into-statement,  Prev: declare-local-variable,  Up: variables-in-stored-programs

12.8.3.2 Variable `SET' Statement
.................................

     SET VAR_NAME = EXPR [, VAR_NAME = EXPR] ...

The `SET' statement in stored programs is an extended version of the
general *Note `SET': set-option.  statement (see *Note set-option::).
Referenced variables may be ones declared inside a stored program,
global system variables, or user-defined variables.

The `SET' statement in stored programs is implemented as part of the
pre-existing *Note `SET': set-option.  syntax. This allows an extended
syntax of `SET a=x, b=y, ...' where different variable types (locally
declared variables, global and session server variables, user-defined
variables) can be mixed. This also allows combinations of local
variables and some options that make sense only for system variables;
in that case, the options are recognized but ignored.


File: manual.info,  Node: select-into-statement,  Next: local-variable-scope,  Prev: set-statement,  Up: variables-in-stored-programs

12.8.3.3 `SELECT ... INTO' Statement
....................................

     SELECT COL_NAME [, COL_NAME] ...
         INTO VAR_NAME [, VAR_NAME] ...
         TABLE_EXPR

`SELECT ... INTO' syntax enables selected columns to be stored directly
into variables. The query should return a single row. If the query
returns no rows, a warning with error code 1329 occurs (`No data'), and
the variable values remain unchanged. If the query returns multiple
rows, error 1172 occurs (`Result consisted of more than one row'). If
it is possible that the statement may retrieve multiple rows, you can
use `LIMIT 1' to limit the result set to a single row.

In the context of such statements that occur as part of events executed
by the Event Scheduler, diagnostics messages (not only errors, but also
warnings) are written to the error log, and, on Windows, to the
application event log. For additional information, see *Note
events-status-info::.

     SELECT id,data INTO x,y FROM test.t1 LIMIT 1;

User variable names are not case sensitive. See *Note user-variables::.


File: manual.info,  Node: local-variable-scope,  Prev: select-into-statement,  Up: variables-in-stored-programs

12.8.3.4 Scope and Resolution of Local Variables
................................................

The scope of a local variable is within the `BEGIN ...  END' block
where it is declared. The variable can be referred to in blocks nested
within the declaring block, except those blocks that declare a variable
with the same name.

Local variable names should not be the same as column names. If an SQL
statement, such as a `SELECT ... INTO' statement, contains a reference
to a column and a declared local variable with the same name, MySQL
currently interprets the reference as the name of a variable. For
example, in the following statement, `xname' is interpreted as a
reference to the `xname' _variable_ rather than the `xname' _column_:

     CREATE PROCEDURE sp1 (x VARCHAR(5))
       BEGIN
         DECLARE xname VARCHAR(5) DEFAULT 'bob';
         DECLARE newname VARCHAR(5);
         DECLARE xid INT;

         SELECT xname,id INTO newname,xid
           FROM table1 WHERE xname = xname;
         SELECT newname;
       END;

When this procedure is called, the `newname' variable returns the value
`'bob'' regardless of the value of the `table1.xname' column.

See also *Note stored-program-restrictions::.


File: manual.info,  Node: conditions-and-handlers,  Next: cursors,  Prev: variables-in-stored-programs,  Up: sql-syntax-compound-statements

12.8.4 Conditions and Handlers
------------------------------

* Menu:

* declare-condition::            `DECLARE' for Conditions
* declare-handler::              `DECLARE' for Handlers

Certain conditions may require specific handling. These conditions can
relate to errors or warnings, as well as to general flow control inside
a stored program.


File: manual.info,  Node: declare-condition,  Next: declare-handler,  Prev: conditions-and-handlers,  Up: conditions-and-handlers

12.8.4.1 `DECLARE' for Conditions
.................................

     DECLARE CONDITION_NAME CONDITION FOR CONDITION_VALUE

     CONDITION_VALUE:
         SQLSTATE [VALUE] SQLSTATE_VALUE
       | MYSQL_ERROR_CODE

The `DECLARE ... CONDITION' statement defines a named error condition.
It specifies a condition that needs specific handling and associates a
name with that condition. The name can be referred to in a subsequence
`DECLARE ...  HANDLER' statement. See *Note declare-handler::.

A CONDITION_VALUE for `DECLARE ... CONDITION' can be an SQLSTATE value
(a 5-character string literal) or a MySQL error code (a number). You
should not use SQLSTATE value `'00000'' or MySQL error code 0, because
those indicate sucess rather than an error condition. For a list of
SQLSTATE values and MySQL error codes, see *Note
error-messages-server::.


File: manual.info,  Node: declare-handler,  Prev: declare-condition,  Up: conditions-and-handlers

12.8.4.2 `DECLARE' for Handlers
...............................

     DECLARE HANDLER_TYPE HANDLER
         FOR CONDITION_VALUE [, CONDITION_VALUE] ...
         STATEMENT

     HANDLER_TYPE:
         CONTINUE
       | EXIT
       | UNDO

     CONDITION_VALUE:
         SQLSTATE [VALUE] SQLSTATE_VALUE
       | CONDITION_NAME
       | SQLWARNING
       | NOT FOUND
       | SQLEXCEPTION
       | MYSQL_ERROR_CODE

The `DECLARE ... HANDLER' statement specifies handlers that each may
deal with one or more conditions. If one of these conditions occurs,
the specified STATEMENT is executed.  STATEMENT can be a simple
statement (for example, `SET VAR_NAME = VALUE'), or it can be a
compound statement written using `BEGIN' and `END' (see *Note
begin-end::).

For a `CONTINUE' handler, execution of the current program continues
after execution of the handler statement. For an `EXIT' handler,
execution terminates for the `BEGIN ... END' compound statement in
which the handler is declared. (This is true even if the condition
occurs in an inner block.) The `UNDO' handler type statement is not
supported.

If a condition occurs for which no handler has been declared, the
default action is `EXIT'.

A CONDITION_VALUE for `DECLARE ... HANDLER' can be any of the following
values:

   * An SQLSTATE value (a 5-character string literal) or a MySQL error
     code (a number). You should not use SQLSTATE value `'00000'' or
     MySQL error code 0, because those indicate sucess rather than an
     error condition. For a list of SQLSTATE values and MySQL error
     codes, see *Note error-messages-server::.

   * A condition name previously specified with `DECLARE ...
     CONDITION'. See *Note declare-condition::.

   * `SQLWARNING' is shorthand for the class of SQLSTATE values that
     begin with `'01''.

   * `NOT FOUND' is shorthand for the class of SQLSTATE values that
     begin with `'02''.  This is relevant only the context of cursors
     and is used to control what happens when a cursor reaches the end
     of a data set. If no more rows are available, a No Data condition
     occurs with SQLSTATE value 02000. To detect this condition, you
     can set up a handler for it (or for a `NOT FOUND' condition). An
     example is shown in *Note cursors::. This condition also occurs for
     `SELECT ... INTO VAR_LIST' statements that retrieve no rows.

   * `SQLEXCEPTION' is shorthand for the class of SQLSTATE values that
     do not begin with `'00'', `'01'', or `'02''.

Example:

     mysql> CREATE TABLE test.t (s1 INT, PRIMARY KEY (s1));
     Query OK, 0 rows affected (0.00 sec)

     mysql> delimiter //

     mysql> CREATE PROCEDURE handlerdemo ()
         -> BEGIN
         ->   DECLARE CONTINUE HANDLER FOR SQLSTATE '23000' SET @x2 = 1;
         ->   SET @x = 1;
         ->   INSERT INTO test.t VALUES (1);
         ->   SET @x = 2;
         ->   INSERT INTO test.t VALUES (1);
         ->   SET @x = 3;
         -> END;
         -> //
     Query OK, 0 rows affected (0.00 sec)

     mysql> CALL handlerdemo()//
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @x//
         +------+
         | @x   |
         +------+
         | 3    |
         +------+
         1 row in set (0.00 sec)

The example associates a handler with SQLSTATE value `'23000'', which
occurs for a duplicate-key error. Notice that `@x' is `3' after the
procedure executes, which shows that execution continued to the end of
the procedure. If the `DECLARE ... HANDLER' statement had not been
present, MySQL would have taken the default path (`EXIT') after the
second *Note `INSERT': insert. failed due to the `PRIMARY KEY'
constraint, and `SELECT @x' would have returned `2'.

If you want to ignore a condition, you can declare a `CONTINUE' handler
for it and associate it with an empty block. For example:

     DECLARE CONTINUE HANDLER FOR SQLWARNING BEGIN END;

The statement associated with a handler cannot use *Note `ITERATE':
iterate-statement.  or *Note `LEAVE': leave-statement.  to refer to
labels for blocks that enclose the handler declaration. That is, the
scope of a block label does not include the code for handlers declared
within the block.  Consider the following example, where the *Note
`REPEAT': repeat-statement.  block has a label of `retry':

     CREATE PROCEDURE p ()
     BEGIN
       DECLARE i INT DEFAULT 3;
       retry:
         REPEAT
           BEGIN
             DECLARE CONTINUE HANDLER FOR SQLWARNING
               BEGIN
                 ITERATE retry;  # illegal
               END;
           END;
           IF i < 0 THEN
             LEAVE retry;        # legal
           END IF;
           SET i = i - 1;
         UNTIL FALSE END REPEAT;
     END;

The label is in scope for the *Note `IF': if-statement.  statement
within the block. It is not in scope for the `CONTINUE' handler, so the
reference there is invalid and results in an error:

     ERROR 1308 (42000): LEAVE with no matching label: retry

To avoid using references to outer labels in handlers, you can use
these strategies:

   * To leave the block, use an `EXIT' handler:

          DECLARE EXIT HANDLER FOR SQLWARNING BEGIN END;

   * To iterate, set a status variable in the handler that can be
     checked in the enclosing block to determine whether the handler
     was invoked. The following example uses the variable `done' for
     this purpose:

          CREATE PROCEDURE p ()
          BEGIN
            DECLARE i INT DEFAULT 3;
            DECLARE done INT DEFAULT FALSE;
            retry:
              REPEAT
                BEGIN
                  DECLARE CONTINUE HANDLER FOR SQLWARNING
                    BEGIN
                      SET done = TRUE;
                    END;
                END;
                IF NOT done AND i < 0 THEN
                  LEAVE retry;
                END IF;
                SET i = i - 1;
              UNTIL FALSE END REPEAT;
          END;


File: manual.info,  Node: cursors,  Next: flow-control-constructs,  Prev: conditions-and-handlers,  Up: sql-syntax-compound-statements

12.8.5 Cursors
--------------

* Menu:

* declare-cursor::               `DECLARE' for Cursors
* open::                         Cursor `OPEN' Statement
* fetch::                        Cursor `FETCH' Statement
* close::                        Cursor `CLOSE' Statement

Cursors are supported inside stored routines, triggers, and events. The
syntax is as in embedded SQL. Cursors in MySQL have these properties:

   * Asensitive: The server may or may not make a copy of its result
     table

   * Read only: Not updatable

   * Non-scrollable: Can be traversed only in one direction and cannot
     skip rows

Cursors must be declared before declaring handlers. Variables and
conditions must be declared before declaring either cursors or handlers.

Example:

     CREATE PROCEDURE curdemo()
     BEGIN
       DECLARE done INT DEFAULT 0;
       DECLARE a CHAR(16);
       DECLARE b,c INT;
       DECLARE cur1 CURSOR FOR SELECT id,data FROM test.t1;
       DECLARE cur2 CURSOR FOR SELECT i FROM test.t2;
       DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

       OPEN cur1;
       OPEN cur2;

       REPEAT
         FETCH cur1 INTO a, b;
         FETCH cur2 INTO c;
         IF NOT done THEN
            IF b < c THEN
               INSERT INTO test.t3 VALUES (a,b);
            ELSE
               INSERT INTO test.t3 VALUES (a,c);
            END IF;
         END IF;
       UNTIL done END REPEAT;

       CLOSE cur1;
       CLOSE cur2;
     END


File: manual.info,  Node: declare-cursor,  Next: open,  Prev: cursors,  Up: cursors

12.8.5.1 `DECLARE' for Cursors
..............................

     DECLARE CURSOR_NAME CURSOR FOR SELECT_STATEMENT

This statement declares a cursor. Multiple cursors may be declared in a
stored program, but each cursor in a given block must have a unique
name.

The *Note `SELECT': select. statement cannot have an `INTO' clause.


File: manual.info,  Node: open,  Next: fetch,  Prev: declare-cursor,  Up: cursors

12.8.5.2 Cursor `OPEN' Statement
................................

     OPEN CURSOR_NAME

This statement opens a previously declared cursor.


File: manual.info,  Node: fetch,  Next: close,  Prev: open,  Up: cursors

12.8.5.3 Cursor `FETCH' Statement
.................................

     FETCH CURSOR_NAME INTO VAR_NAME [, VAR_NAME] ...

This statement fetches the next row (if a row exists) using the
specified open cursor, and advances the cursor pointer.

If no more rows are available, a No Data condition occurs with SQLSTATE
value 02000. To detect this condition, you can set up a handler for it
(or for a `NOT FOUND' condition). An example is shown in *Note
cursors::.


File: manual.info,  Node: close,  Prev: fetch,  Up: cursors

12.8.5.4 Cursor `CLOSE' Statement
.................................

     CLOSE CURSOR_NAME

This statement closes a previously opened cursor.

If not closed explicitly, a cursor is closed at the end of the compound
statement in which it was declared.


File: manual.info,  Node: flow-control-constructs,  Next: return,  Prev: cursors,  Up: sql-syntax-compound-statements

12.8.6 Flow Control Constructs
------------------------------

* Menu:

* if-statement::                 `IF' Statement
* case-statement::               `CASE' Statement
* loop-statement::               `LOOP' Statement
* leave-statement::              `LEAVE' Statement
* iterate-statement::            `ITERATE' Statement
* repeat-statement::             `REPEAT' Statement
* while-statement::              `WHILE' Statement

MySQL supports the *Note `IF': if-statement, *Note `CASE':
case-statement, *Note `ITERATE': iterate-statement, *Note `LEAVE':
leave-statement.  *Note `LOOP': loop-statement, *Note `WHILE':
while-statement, and *Note `REPEAT': repeat-statement.  constructs for
flow control within stored programs.

Many of these constructs contain other statements, as indicated by the
grammar specifications in the following sections. Such constructs may
be nested. For example, an *Note `IF': if-statement.  statement might
contain a *Note `WHILE': while-statement.  loop, which itself contains a
*Note `CASE': case-statement.  statement.

`FOR' loops are not supported.


File: manual.info,  Node: if-statement,  Next: case-statement,  Prev: flow-control-constructs,  Up: flow-control-constructs

12.8.6.1 `IF' Statement
.......................

     IF SEARCH_CONDITION THEN STATEMENT_LIST
         [ELSEIF SEARCH_CONDITION THEN STATEMENT_LIST] ...
         [ELSE STATEMENT_LIST]
     END IF

*Note `IF': if-statement.  implements a basic conditional construct. If
the SEARCH_CONDITION evaluates to true, the corresponding SQL statement
list is executed. If no SEARCH_CONDITION matches, the statement list in
the `ELSE' clause is executed. Each STATEMENT_LIST consists of one or
more statements.

*Note*:

There is also an `IF()' _function_, which differs from the *Note `IF':
if-statement.  _statement_ described here. See *Note
control-flow-functions::.

An `IF ... END IF' block, like all other flow-control blocks used
within stored programs, must be terminated with a semicolon, as shown
in this example:

     DELIMITER //

     CREATE FUNCTION SimpleCompare(n INT, m INT)
       RETURNS VARCHAR(20)

       BEGIN
         DECLARE s VARCHAR(20);

         IF n > m THEN SET s = '>';
         ELSEIF n = m THEN SET s = '=';
         ELSE SET s = '<';
         END IF;

         SET s = CONCAT(n, ' ', s, ' ', m);

         RETURN s;
       END //

     DELIMITER ;

As with other flow-control constructs, `IF ... END IF' blocks may be
nested within other flow-control constructs, including other *Note
`IF': if-statement.  statements. Each *Note `IF': if-statement. must be
terminated by its own `END IF' followed by a semicolon. You can use
indentation to make nested flow-control blocks more easily readable by
humans (although this is not required by MySQL), as shown here:

     DELIMITER //

     CREATE FUNCTION VerboseCompare (n INT, m INT)
       RETURNS VARCHAR(50)

       BEGIN
         DECLARE s VARCHAR(50);

         IF n = m THEN SET s = 'equals';
         ELSE
           IF n > m THEN SET s = 'greater';
           ELSE SET s = 'less';
           END IF;

           SET s = CONCAT('is ', s, ' than');
         END IF;

         SET s = CONCAT(n, ' ', s, ' ', m, '.');

         RETURN s;
       END //

     DELIMITER ;

In this example, the inner *Note `IF': if-statement. is evaluated only
if `n' is not equal to `m'.


File: manual.info,  Node: case-statement,  Next: loop-statement,  Prev: if-statement,  Up: flow-control-constructs

12.8.6.2 `CASE' Statement
.........................

     CASE CASE_VALUE
         WHEN WHEN_VALUE THEN STATEMENT_LIST
         [WHEN WHEN_VALUE THEN STATEMENT_LIST] ...
         [ELSE STATEMENT_LIST]
     END CASE

Or:

     CASE
         WHEN SEARCH_CONDITION THEN STATEMENT_LIST
         [WHEN SEARCH_CONDITION THEN STATEMENT_LIST] ...
         [ELSE STATEMENT_LIST]
     END CASE

The *Note `CASE': case-statement.  statement for stored programs
implements a complex conditional construct. If a SEARCH_CONDITION
evaluates to true, the corresponding SQL statement list is executed. If
no search condition matches, the statement list in the `ELSE' clause is
executed. Each STATEMENT_LIST consists of one or more statements.

If no WHEN_VALUE or SEARCH_CONDITION matches the value tested and the
*Note `CASE': case-statement.  statement contains no `ELSE' clause, a
`Case not found for CASE statement' error results.

Each STATEMENT_LIST consists of one or more statements; an empty
STATEMENT_LIST is not allowed. To handle situations where no value is
matched by any `WHEN' clause, use an `ELSE' containing an empty `BEGIN
... END' block, as shown in this example:

     DELIMITER |

     CREATE PROCEDURE p()
       BEGIN
         DECLARE v INT DEFAULT 1;

         CASE v
           WHEN 2 THEN SELECT v;
           WHEN 3 THEN SELECT 0;
           ELSE
             BEGIN
             END;
         END CASE;
       END;
       |

(The indentation used here in the `ELSE' clause is for purposes of
clarity only, and is not otherwise significant.)

*Note*:

The syntax of the *Note `CASE': case-statement.  _statement_ used
inside stored programs differs slightly from that of the SQL `CASE'
_expression_ described in *Note control-flow-functions::. The *Note
`CASE': case-statement.  statement cannot have an `ELSE NULL' clause,
and it is terminated with `END CASE' instead of `END'.


File: manual.info,  Node: loop-statement,  Next: leave-statement,  Prev: case-statement,  Up: flow-control-constructs

12.8.6.3 `LOOP' Statement
.........................

     [BEGIN_LABEL:] LOOP
         STATEMENT_LIST
     END LOOP [END_LABEL]

*Note `LOOP': loop-statement.  implements a simple loop construct,
enabling repeated execution of the statement list, which consists of
one or more statements, each terminated by a semicolon (`;') statement
delimiter. The statements within the loop are repeated until the loop
is exited; usually this is accomplished with a *Note `LEAVE':
leave-statement.  statement.

A *Note `LOOP': loop-statement.  statement can be labeled. END_LABEL
cannot be given unless BEGIN_LABEL also is present. If both are
present, they must be the same.


File: manual.info,  Node: leave-statement,  Next: iterate-statement,  Prev: loop-statement,  Up: flow-control-constructs

12.8.6.4 `LEAVE' Statement
..........................

     LEAVE LABEL

This statement is used to exit the flow control construct that has the
given label. It can be used within `BEGIN ...  END' or loop constructs
(*Note `LOOP': loop-statement, *Note `REPEAT': repeat-statement, *Note
`WHILE': while-statement.).


File: manual.info,  Node: iterate-statement,  Next: repeat-statement,  Prev: leave-statement,  Up: flow-control-constructs

12.8.6.5 `ITERATE' Statement
............................

     ITERATE LABEL

*Note `ITERATE': iterate-statement.  can appear only within *Note
`LOOP': loop-statement, *Note `REPEAT': repeat-statement, and *Note
`WHILE': while-statement.  statements.  *Note `ITERATE':
iterate-statement.  means `do the loop again.'

Example:

     CREATE PROCEDURE doiterate(p1 INT)
     BEGIN
       label1: LOOP
         SET p1 = p1 + 1;
         IF p1 < 10 THEN ITERATE label1; END IF;
         LEAVE label1;
       END LOOP label1;
       SET @x = p1;
     END


File: manual.info,  Node: repeat-statement,  Next: while-statement,  Prev: iterate-statement,  Up: flow-control-constructs

12.8.6.6 `REPEAT' Statement
...........................

     [BEGIN_LABEL:] REPEAT
         STATEMENT_LIST
     UNTIL SEARCH_CONDITION
     END REPEAT [END_LABEL]

The statement list within a *Note `REPEAT': repeat-statement.
statement is repeated until the SEARCH_CONDITION is true. Thus, a *Note
`REPEAT': repeat-statement.  always enters the loop at least once.
STATEMENT_LIST consists of one or more statements, each terminated by a
semicolon (`;') statement delimiter.

A *Note `REPEAT': repeat-statement.  statement can be labeled. END_LABEL
cannot be given unless BEGIN_LABEL also is present. If both are
present, they must be the same.

Example:

     mysql> delimiter //

     mysql> CREATE PROCEDURE dorepeat(p1 INT)
         -> BEGIN
         ->   SET @x = 0;
         ->   REPEAT SET @x = @x + 1; UNTIL @x > p1 END REPEAT;
         -> END
         -> //
     Query OK, 0 rows affected (0.00 sec)

     mysql> CALL dorepeat(1000)//
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @x//
     +------+
     | @x   |
     +------+
     | 1001 |
     +------+
     1 row in set (0.00 sec)


File: manual.info,  Node: while-statement,  Prev: repeat-statement,  Up: flow-control-constructs

12.8.6.7 `WHILE' Statement
..........................

     [BEGIN_LABEL:] WHILE SEARCH_CONDITION DO
         STATEMENT_LIST
     END WHILE [END_LABEL]

The statement list within a *Note `WHILE': while-statement.  statement
is repeated as long as the SEARCH_CONDITION is true.  STATEMENT_LIST
consists of one or more statements.

A *Note `WHILE': while-statement.  statement can be labeled. END_LABEL
cannot be given unless BEGIN_LABEL also is present. If both are
present, they must be the same.

Example:

     CREATE PROCEDURE dowhile()
     BEGIN
       DECLARE v1 INT DEFAULT 5;

       WHILE v1 > 0 DO
         ...
         SET v1 = v1 - 1;
       END WHILE;
     END


File: manual.info,  Node: return,  Next: signal-resignal,  Prev: flow-control-constructs,  Up: sql-syntax-compound-statements

12.8.7 `RETURN' Syntax
----------------------

     RETURN EXPR

The *Note `RETURN': return. statement terminates execution of a stored
function and returns the value EXPR to the function caller. There must
be at least one *Note `RETURN': return. statement in a stored function.
There may be more than one if the function has multiple exit points.

This statement is not used in stored procedures, triggers, or events.


File: manual.info,  Node: signal-resignal,  Prev: return,  Up: sql-syntax-compound-statements

12.8.8 `SIGNAL' and `RESIGNAL'
------------------------------

* Menu:

* signal::                       `SIGNAL' Syntax
* resignal::                     `RESIGNAL' Syntax

This section documents the *Note `SIGNAL': signal.  and *Note
`RESIGNAL': resignal. statements. See also *Note signal-restrictions::.


File: manual.info,  Node: signal,  Next: resignal,  Prev: signal-resignal,  Up: signal-resignal

12.8.8.1 `SIGNAL' Syntax
........................

* Menu:

* signal-condition-information-items::  Signal Condition Information Items
* signal-effects::               Effect of Signals on Handlers, Cursors, and Statements

     SIGNAL CONDITION_VALUE
         [SET SIGNAL_INFORMATION [, SIGNAL_INFORMATION] ...]

     CONDITION_VALUE:
         SQLSTATE [VALUE] SQLSTATE_VALUE
       | CONDITION_NAME

     SIGNAL_INFORMATION:
         CONDITION_INFORMATION_ITEM = SIMPLE_VALUE_SPECIFICATION

     CONDITION_INFORMATION_ITEM:
     {
         CLASS_ORIGIN
       | SUBCLASS_ORIGIN
       | CONSTRAINT_CATALOG
       | CONSTRAINT_SCHEMA
       | CONSTRAINT_NAME
       | CATALOG_NAME
       | SCHEMA_NAME
       | TABLE_NAME
       | COLUMN_NAME
       | CURSOR_NAME
       | MESSAGE_TEXT
       | MYSQL_ERRNO
     }

     SIMPLE_VALUE_SPECIFICATION: (see following discussion)

*Note `SIGNAL': signal. is the way to `return' an error.  *Note
`SIGNAL': signal. provides error information to a handler, to an outer
portion of the application, or to the client. Also, it provides control
over the error's characteristics (error number, `SQLSTATE' value,
message). Without *Note `SIGNAL': signal, it is necessary to resort to
workarounds such as deliberately referring to a non-existent table to
cause a routine to return an error. This statement was added in MySQL
6.0.11.

No special privileges are required to execute the *Note `SIGNAL':
signal. statement.

The CONDITION_VALUE in a *Note `SIGNAL': signal. statement indicates the
error value to be returned. It can be an `SQLSTATE' value (a
5-character string literal) or a CONDITION_NAME that refers to a named
condition previously defined with *Note `DECLARE ... CONDITION':
declare-condition. (see *Note declare-condition::).

An `SQLSTATE' value can indicate errors, warnings, or `not found.' The
first two characters of the value indicate its error class, as
discussed in *Note signal-condition-information-items::. Some signal
values cause statement termination; see *Note signal-effects::.

The `SQLSTATE' value for a *Note `SIGNAL': signal. statement should not
start with `'00'' because such values indicate success and are not
valid for signaling an error. This is true whether the `SQLSTATE' value
is specified directly in the *Note `SIGNAL': signal. statement or in a
named condition referred to in the statement. If the value is invalid,
a `Bad SQLSTATE' error occurs.

To signal a generic `SQLSTATE' value, use `'45000'', which means
`unhandled user-defined exception.'

The *Note `SIGNAL': signal. statement optionally includes a `SET'
clause that contains multiple signal items, in a comma-separated list of
CONDITION_INFORMATION_ITEM = SIMPLE_VALUE_SPECIFICATION assignments.

All CONDITION_INFORMATION_ITEM values are standard SQL except
`MYSQL_ERRNO', which is a MySQL extension.  *Note
signal-condition-information-items::. discusses allowable
CONDITION_INFORMATION_ITEM values.

Each CONDITION_INFORMATION_ITEM may be specified only once in the `SET'
clause.  Otherwise, a `Duplicate condition information item' error
occurs.

For MySQL, valid SIMPLE_VALUE_SPECIFICATION terms include local
variables declared with *Note `DECLARE': declare, user-defined
variables, system variables, parameters (that is, input parameters of
functions or procedures), and literals, but not `NULL' values. A
character literal may include a _CHARSET introducer.

The following procedure signals an error or warning depending on the
value of `pval', its input parameter:

     CREATE PROCEDURE p (pval INT)
     BEGIN
       DECLARE specialty CONDITION FOR SQLSTATE '45000';
       IF pval = 0 THEN
         SIGNAL SQLSTATE '01000';
       ELSEIF pval = 1 THEN
         SIGNAL SQLSTATE '45000'
           SET MESSAGE_TEXT = 'An error occurred';
       ELSEIF pval = 2 THEN
         SIGNAL specialty
           SET MESSAGE_TEXT = 'An error occurred';
       ELSE
         SIGNAL SQLSTATE '01000'
           SET MESSAGE_TEXT = 'A warning occurred', MYSQL_ERRNO = 1000;
         SIGNAL SQLSTATE '45000'
           SET MESSAGE_TEXT = 'An error occurred', MYSQL_ERRNO = 1001;
       END IF;
     END;

If `pval' is 0, `p()' signals a warning because `SQLSTATE' values that
begin with `'01'' are signals in the warning class.  The warning does
not terminate the procedure, and can be seen with *Note `SHOW
WARNINGS': show-warnings. after the procedure returns.

If `pval' is 1, `p()' signals an error and sets the `MESSAGE_TEXT'
condition information item. The error terminates the procedure, and the
text is returned with the error information.

If `pval' is 2, the same error is signaled, although the `SQLSTATE'
value is specified using a named condition in this case.

If `pval' is anything else, `p()' first signals a warning and sets the
message text and error number condition information items. This warning
does not terminate the procedure, so execution continues and `p()' then
signals an error. The error does terminate the procedure. The message
text and error number set by the warning are replaced by the values set
by the error, which are returned with the error information.

*Note `SIGNAL': signal. is typically used within compound statements,
but it is a MySQL extension that *Note `SIGNAL': signal. is allowed
outside compound statements, For example, if you invoke the *Note
`mysql': mysql. program, you can enter any of these statements at the
prompt:

     mysql> SIGNAL SQLSTATE '77777';
     mysql> CREATE TRIGGER t_bi BEFORE INSERT ON t
         -> FOR EACH ROW SIGNAL SQLSTATE '77777';
     mysql> CREATE EVENT e ON SCHEDULE EVERY 1 SECOND
         -> DO SIGNAL SQLSTATE '77777';

*Note `SIGNAL': signal. executes according to the following rules:

If the *Note `SIGNAL': signal. statement indicates a particular
`SQLSTATE' value, that value is used to signal the condition specified.
Example:

     CREATE PROCEDURE p (divisor INT)
     BEGIN
       IF divisor = 0 THEN
         SIGNAL SQLSTATE '22012';
       END IF;
     END;

If the *Note `SIGNAL': signal. statement uses a named condition, the
condition must satisfy the following requirements:

   * The condition must be declared in some scope that applies to the
     *Note `SIGNAL': signal. statement.

   * The condition must be defined with `SQLSTATE', not with a MySQL
     error number.

Example:

     CREATE PROCEDURE p (divisor INT)
     BEGIN
       DECLARE divide_by_zero CONDITION FOR SQLSTATE '22012';
       IF divisor = 0 THEN
         SIGNAL divide_by_zero;
       END IF;
     END;

If the named condition does not exist in the scope of the *Note
`SIGNAL': signal. statement, an `Undefined CONDITION' error occurs.

If *Note `SIGNAL': signal. refers to a named condition that is not
defined with `SQLSTATE', a `SIGNAL/RESIGNAL can only use a CONDITION
defined with SQLSTATE' error occurs. The following statements cause
that error because the condition is associated with a MySQL error
number:

     DECLARE x CONDITION FOR 1234;
     SIGNAL x;

If a named condition is declared multiple times, the declaration with
the most local scope applies. Consider the following procedure:

     CREATE PROCEDURE p (divisor INT)
     BEGIN
       DECLARE my_error CONDITION FOR SQLSTATE '45000';
       IF divisor = 0 THEN
         BEGIN
           DECLARE my_error CONDITION FOR SQLSTATE '22012';
           SIGNAL my_error;
         END;
       END IF;
       SIGNAL my_error;
     END;

If `divisor' is 0, the first *Note `SIGNAL': signal. statement
executes. The innermost `my_error' condition declaration applies,
raising `SQLSTATE' value `'22012''.

If `divisor' is not 0, the second *Note `SIGNAL': signal. statement
executes. The outermost `my_error' condition declaration applies,
raising `SQLSTATE' value `'45000''.

Signals can be raised within exception handlers:

     CREATE PROCEDURE p ()
     BEGIN
       DECLARE EXIT HANDLER FOR SQLEXCEPTION
       BEGIN
         SIGNAL SQLSTATE VALUE '99999'
           SET MESSAGE_TEXT = 'An error occurred';
       END;
       DROP TABLE no_such_table;
     END;

`CALL p()' reaches the *Note `DROP TABLE': drop-table. statement. There
is no table named `no_such_table', so the error handler comes into
play. The error handler destroys the original error (`no such table')
and makes a new error with `SQLSTATE' value `'99999'' and message `An
error occurred'.


File: manual.info,  Node: signal-condition-information-items,  Next: signal-effects,  Prev: signal,  Up: signal

12.8.8.2 Signal Condition Information Items
...........................................

The following table lists the condition information items that can be
set in a *Note `SIGNAL': signal.  statement. All items are standard SQL
except `MYSQL_ERRNO', which is a MySQL extension.

     Item Name             Definition
     ---------             ----------
     CLASS_ORIGIN          VARCHAR(64)
     SUBCLASS_ORIGIN       VARCHAR(64)
     CONSTRAINT_CATALOG    VARCHAR(64)
     CONSTRAINT_SCHEMA     VARCHAR(64)
     CONSTRAINT_NAME       VARCHAR(64)
     CATALOG_NAME          VARCHAR(64)
     SCHEMA_NAME           VARCHAR(64)
     TABLE_NAME            VARCHAR(64)
     COLUMN_NAME           VARCHAR(64)
     CURSOR_NAME           VARCHAR(64)
     MESSAGE_TEXT          VARCHAR(128)
     MYSQL_ERRNO           SMALLINT UNSIGNED

All character items are UTF-8. UTF-8 may have 4-byte characters, so
*Note `VARCHAR(128)': char. can require 512 bytes. Characters that are
not valid UTF-8 are converted to `'?'' characters.

It is illegal to assign `NULL' to a condition information item in a
*Note `SIGNAL': signal.  statement.

A *Note `SIGNAL': signal. statement always specifies an `SQLSTATE'
value, either directly, or indirectly by referring to a named condition
defined with an `SQLSTATE' value. The first two letters of an
`SQLSTATE' value are its class, and the class determines the default
value for the condition information items:

   * Class = `'00'' (success)

     Illegal. This cannot happen because `SQLSTATE' values that begin
     with `'00'' indicate success and are not valid for *Note `SIGNAL':
     signal.

   * Class = `'01'' (warning)

          MESSAGE_TEXT = 'Unhandled user-defined warning';
          MYSQL_ERRNO = ER_SIGNAL_WARN

   * Class = `'02'' (not found)

          MESSAGE_TEXT = 'Unhandled user-defined not found';
          MYSQL_ERRNO = ER_SIGNAL_NOT_FOUND

   * Class > `'02'' (exception)

          MESSAGE_TEXT = 'Unhandled user-defined exception';
          MYSQL_ERRNO = ER_SIGNAL_EXCEPTION

For legal classes, the other condition information items are set as
follows:

     CLASS_ORIGIN = SUBCLASS_ORIGIN = '';
     CONSTRAINT_CATALOG = CONSTRAINT_SCHEMA = CONSTRAINT_NAME = '';
     CATALOG_NAME = SCHEMA_NAME = TABLE_NAME = COLUMN_NAME = '';
     CURSOR_NAME = '';

The error values that are accessible after *Note `SIGNAL': signal.
executes are the `SQLSTATE' value raised by the *Note `SIGNAL': signal.
statement and the `MESSAGE_TEXT' and `MYSQL_ERRNO' items. These values
are available from the C API:

   * `SQLSTATE' value: Call *Note `mysql_sqlstate()': mysql-sqlstate.

   * `MYSQL_ERRNO' value: Call *Note `mysql_errno()': mysql-errno.

   * `MESSAGE_TEXT' value: Call *Note `mysql_error()': mysql-error.

From SQL, the output from *Note `SHOW WARNINGS': show-warnings. and
*Note `SHOW ERRORS': show-errors. indicates the `MYSQL_ERRNO' and
`MESSAGE_TEXT' values in the `Code' and `Message' columns.

Other condition information items can be set, but currently have no
effect, in the sense that they are not accessible from error returns.
For example, you can set `CLASS_ORIGIN' in a *Note `SIGNAL': signal.
statement, but cannot see it after *Note `SIGNAL': signal. executes.


File: manual.info,  Node: signal-effects,  Prev: signal-condition-information-items,  Up: signal

12.8.8.3 Effect of Signals on Handlers, Cursors, and Statements
...............................................................

Signals have different effects on statement execution depending on the
signal class. The class determines how severe an error is. MySQL
ignores the `sql_mode' value; in particular, strict SQL mode does not
matter. MySQL also ignores `IGNORE': The intent of *Note `SIGNAL':
signal. is to raise a user-generated error explicitly, so a signal is
never ignored.

In the following descriptions, `unhandled' means that no handler for
the signaled `SQLSTATE' value has been defined with *Note `DECLARE ...
HANDLER': declare-handler.

   * Class = `'00'' (success)

     Illegal. This cannot happen because `SQLSTATE' values that begin
     with `'00'' indicate success and are not valid for *Note `SIGNAL':
     signal.

   * Class = `'01'' (warning)

     The value of the `warning_count' system variable goes up. *Note
     `SHOW WARNINGS': show-warnings. shows the signal.  `SQLWARNING'
     handlers catch the signal.  If the signal is unhandled in a
     function, statements do not end.

   * Class = `'02'' (not found)

     `NOT FOUND' handlers catch the signal.  There is no effect on
     cursors. If the signal is unhandled in a function, statements end.

   * Class > `'02'' (exception)

     `SQLEXCEPTION' handlers catch the signal.  If the signal is
     unhandled in a function, statements end.

   * Class = `'40''

     Treated as an ordinary exception.

Example:

     mysql> delimiter //
     mysql> CREATE FUNCTION f () RETURNS INT
         -> BEGIN
         ->   SIGNAL SQLSTATE '01234';  -- signal a warning
         ->   RETURN 5;
         -> END//
     mysql> delimiter ;
     mysql> CREATE TABLE t (s1 INT);
     mysql> INSERT INTO t VALUES (f());

The result is that a row containing 5 is inserted into table `t'. The
warning that is signaled can be viewed with *Note `SHOW WARNINGS':
show-warnings.


File: manual.info,  Node: resignal,  Prev: signal,  Up: signal-resignal

12.8.8.4 `RESIGNAL' Syntax
..........................

* Menu:

* resignal-alone::               `RESIGNAL' Alone
* resignal-with-new-signal::     `RESIGNAL' with New Signal Information
* resignal-with-condition::      `RESIGNAL' with a Condition Value and Optional New Signal Information
* resignal-handler::             `RESIGNAL' Requires an Active Handler

     RESIGNAL [CONDITION_VALUE]
         [SET SIGNAL_INFORMATION [, SIGNAL_INFORMATION] ...];

     CONDITION_VALUE:
         SQLSTATE [VALUE] SQLSTATE_VALUE
       | CONDITION_NAME

     SIGNAL_INFORMATION:
         CONDITION_INFORMATION_ITEM = SIMPLE_VALUE_SPECIFICATION

     CONDITION_INFORMATION_ITEM:
     {
         CLASS_ORIGIN
       | SUBCLASS_ORIGIN
       | CONSTRAINT_CATALOG
       | CONSTRAINT_SCHEMA
       | CONSTRAINT_NAME
       | CATALOG_NAME
       | SCHEMA_NAME
       | TABLE_NAME
       | COLUMN_NAME
       | CURSOR_NAME
       | MESSAGE_TEXT
       | MYSQL_ERRNO
     }

     SIMPLE_VALUE_SPECIFICATION: (see following discussion)

*Note `RESIGNAL': resignal. passes on the error condition information
that is available during execution of a condition handler within a
compound statement inside a stored procedure or function, trigger, or
event.  *Note `RESIGNAL': resignal. may change some or all information
before passing it on. This statement was added in MySQL 6.0.11.

*Note `RESIGNAL': resignal. makes it possible to both handle an error
and return the error information.  Otherwise, by executing an SQL
statement within the handler, information that caused the handler's
activation is destroyed.  *Note `RESIGNAL': resignal. also can make some
procedures shorter if a given handler could handle part of a situation,
then pass the condition `up the line' to another handler.

No special privileges are required to execute the *Note `RESIGNAL':
resignal. statement.

Unless otherwise indicated, the definitions and rules for
CONDITION_VALUE and SIGNAL_INFORMATION are the same for the *Note
`RESIGNAL': resignal. statement as for *Note `SIGNAL': signal. (see
*Note signal::).

The *Note `RESIGNAL': resignal. statement takes CONDITION_VALUE and
`SET' clauses, both of which are optional. This leads to several
possible uses:

   * *Note `RESIGNAL': resignal. alone:

          RESIGNAL;

   * *Note `RESIGNAL': resignal. with new signal information:

          RESIGNAL SET SIGNAL_INFORMATION [, SIGNAL_INFORMATION] ...;

   * *Note `RESIGNAL': resignal. with a condition value and possibly
     new signal information:

          RESIGNAL CONDITION_VALUE
              [SET SIGNAL_INFORMATION [, SIGNAL_INFORMATION] ...];

These use cases all cause changes to the diagnostic and condition areas:

   * A diagnostics area contains one or more condition areas.

   * A condition area contains condition information items, such as the
     `SQLSTATE' value, `MYSQL_ERRNO', or `MESSAGE_TEXT'.

There is a stack of diagnostics areas. When a handler takes control, it
pushes the top of the stack, so there are two diagnostics areas during
handler execution:

   * The current diagnostics area, which starts as a copy of the last
     diagnostics area, but will be overwritten by the first procedure
     statement in the handler.

   * The last diagnostics area, which has the condition areas that were
     set up before the handler took control.

The maximum number of condition areas in a diagnostics area is
determined by the value of the `max_error_count' system variable.


File: manual.info,  Node: resignal-alone,  Next: resignal-with-new-signal,  Prev: resignal,  Up: resignal

12.8.8.5 `RESIGNAL' Alone
.........................

A simple *Note `RESIGNAL': resignal. alone means `pass on the error
with no change.' It restores the last diagnostics area and makes it the
current diagnostics area. That is, it `pops' the diagnostics area stack.

Within a condition handler that catches a condition, one use for *Note
`RESIGNAL': resignal. alone is to perform some other actions, and then
pass on without change the original condition information (the
information that existed before entry into the handler).

Example:

     DROP TABLE IF EXISTS xx;
     delimiter //
     CREATE PROCEDURE p ()
     BEGIN
       DECLARE EXIT HANDLER FOR SQLEXCEPTION
       BEGIN
         SET @error_count = @error_count + 1;
         IF @a = 0 THEN RESIGNAL; END IF;
       END;
       DROP TABLE xx;
     END//
     delimiter ;
     SET @error_count = 0;
     SET @a = 0;
     CALL p();

The `DROP TABLE xx' statement fails. The diagnostics area stack looks
like this:

     1. ERROR 1051 (42S02): Unknown table 'xx'

Then execution enters the `EXIT' handler. It starts by pushing the top
of the diagnostics area stack, which now looks like this:

     1. ERROR 1051 (42S02): Unknown table 'xx'
     2. ERROR 1051 (42S02): Unknown table 'xx'

Usually a procedure statement clears the first diagnostics area (also
called the `current' diagnostics area). `BEGIN' is an exception, it
does not clear, it does nothing. `SET' is not an exception, it clears,
performs the operation, and then produces a result of `success.' The
diagnostics area stack now looks like this:

     1. ERROR 0000 (00000): Successful operation
     2. ERROR 1051 (42S02): Unknown table 'xx'

At this point, if `@a = 0', *Note `RESIGNAL': resignal. pops the
diagnostics area stack, which now looks like this:

     1. ERROR 1051 (42S02): Unknown table 'xx'

And that is what the caller sees.

If `@a' is not 0, the handler simply ends, which means that there is no
more use for the last diagnostics area (it has been `handled'), so it
can be thrown away. The diagnostics area stack looks like this:

     1. ERROR 0000 (00000): Successful operation

The details make it look complex, but the end result is quite useful:
Handlers can execute without destroying information about the condition
that caused activation of the handler.


File: manual.info,  Node: resignal-with-new-signal,  Next: resignal-with-condition,  Prev: resignal-alone,  Up: resignal

12.8.8.6 `RESIGNAL' with New Signal Information
...............................................

*Note `RESIGNAL': resignal. with a `SET' clause provides new signal
information, so the statement means `pass on the error with changes':

     RESIGNAL SET SIGNAL_INFORMATION [, SIGNAL_INFORMATION] ...;

As with *Note `RESIGNAL': resignal. alone, the idea is to pop the
diagnostics area stack so that the original information will go out.
Unlike *Note `RESIGNAL': resignal. alone, anything specified in the
`SET' clause changes.

Example:

     DROP TABLE IF EXISTS xx;
     delimiter //
     CREATE PROCEDURE p ()
     BEGIN
       DECLARE EXIT HANDLER FOR SQLEXCEPTION
       BEGIN
         SET @error_count = @error_count + 1;
         IF @a = 0 THEN RESIGNAL SET MYSQL_ERRNO = 5; END IF;
       END;
       DROP TABLE xx;
     END//
     delimiter ;
     SET @error_count = 0;
     SET @a = 0;
     CALL p();

Remember from the previous discussion that *Note `RESIGNAL': resignal.
alone results in a diagnostics area stack like this:

     1. ERROR 1051 (42S02): Unknown table 'xx'

The `RESIGNAL SET MYSQL_ERRNO = 5' statement results in this stack
instead:

     1. ERROR 5 (42S02): Unknown table 'xx'

In other words, it changes the error number, and nothing else.

The *Note `RESIGNAL': resignal. statement can change any or all of the
signal information items, making the first condition area of the
diagnostics area look quite different.


File: manual.info,  Node: resignal-with-condition,  Next: resignal-handler,  Prev: resignal-with-new-signal,  Up: resignal

12.8.8.7 `RESIGNAL' with a Condition Value and Optional New Signal Information
..............................................................................

*Note `RESIGNAL': resignal. with a condition value means `push a
condition into the current diagnostic stack area.' If the `SET' clause
is present, it also changes the error information.

     RESIGNAL CONDITION_VALUE
         [SET SIGNAL_INFORMATION [, SIGNAL_INFORMATION] ...];

This form of *Note `RESIGNAL': resignal. restores the last diagnostics
area and makes it the current diagnostics area. That is, it `pops' the
diagnostics area stack, which is the same as what a simple *Note
`RESIGNAL': resignal. alone would do.  However, it also changes the
diagnostics area depending on the condition value or signal information.

Example:

     DROP TABLE IF EXISTS xx;
     delimiter //
     CREATE PROCEDURE p ()
     BEGIN
       DECLARE EXIT HANDLER FOR SQLEXCEPTION
       BEGIN
         SET @error_count = @error_count + 1;
         IF @a = 0 THEN RESIGNAL SQLSTATE '45000' SET MYSQL_ERRNO=5; END IF;
       END;
       DROP TABLE xx;
     END//
     delimiter ;
     SET @error_count = 0;
     SET @a = 0;
     SET @@max_error_count = 2;
     CALL p();
     SHOW ERRORS;

This is similar to the previous example, and the effects are the same,
except that if *Note `RESIGNAL': resignal. happens the current
condition area looks different at the end. (The reason the condition is
added rather than replaced is the use of a condition value.)

The *Note `RESIGNAL': resignal. statement includes a condition value
(`SQLSTATE '45000''), so it `pushes' a new condition area, resulting in
a diagnostics area stack that looks like this:

     1. (condition 1) ERROR 5 (45000) Unknown table 'xx'
        (condition 2) ERROR 1051 (42S02): Unknown table 'xx'

The result of *Note `CALL p()': call. and *Note `SHOW ERRORS':
show-errors.  for this example is:

     mysql> CALL p();
     ERROR 5 (45000): Unknown table 'xx'
     mysql> SHOW ERRORS;
     +-------+------+----------------------------------+
     | Level | Code | Message                          |
     +-------+------+----------------------------------+
     | Error |    5 | Unknown table 'xx'               |
     | Error | 1051 | Unknown table 'xx'               |
     +-------+------+----------------------------------+


File: manual.info,  Node: resignal-handler,  Prev: resignal-with-condition,  Up: resignal

12.8.8.8 `RESIGNAL' Requires an Active Handler
..............................................

All forms of *Note `RESIGNAL': resignal. require that a handler be
active when it executes. If no handler is active, *Note `RESIGNAL':
resignal. is illegal and a `resignal when handler not active' error
occurs. For example:

     mysql> CREATE PROCEDURE p () RESIGNAL;
     Query OK, 0 rows affected (0.00 sec)

     mysql> CALL p();
     ERROR 1739 (0K000): RESIGNAL when handler not active

Here is a more difficult example:

     delimiter //
     CREATE FUNCTION f () RETURNS INT
     BEGIN
       RESIGNAL;
       RETURN 5;
     END//
     CREATE PROCEDURE p ()
     BEGIN
       DECLARE EXIT HANDLER FOR SQLEXCEPTION SET @a=f();
       SIGNAL SQLSTATE '55555';
     END//
     delimiter ;
     CALL p();

At the time the *Note `RESIGNAL': resignal.  executes, there is a
handler, even though the *Note `RESIGNAL': resignal. is not defined
inside the handler.

A statement such as the one following may appear bizarre because *Note
`RESIGNAL': resignal. apparently is not in a handler:

     CREATE TRIGGER t_bi BEFORE INSERT ON t FOR EACH ROW RESIGNAL;

But it does not matter.  *Note `RESIGNAL': resignal. does not have to be
technically `in' (that is, contained in), a handler declaration. The
requirement is that a handler must be active.


File: manual.info,  Node: storage-engines,  Next: ha-overview,  Prev: sql-syntax,  Up: Top

13 Storage Engines
******************

* Menu:

* storage-engine-compare-transactions::  Comparing Transaction and Non-Transaction Engines
* storage-engines-other::        Other Storage Engines
* storage-engine-setting::       Setting the Storage Engine
* pluggable-storage-overview::   Overview of MySQL Storage Engine Architecture
* myisam-storage-engine::        The `MyISAM' Storage Engine
* se-maria::                     The `Maria' Storage Engine
* innodb::                       The `InnoDB' Storage Engine
* se-falcon::                    The `Falcon' Storage Engine
* merge-storage-engine::         The `MERGE' Storage Engine
* memory-storage-engine::        The `MEMORY' (`HEAP') Storage Engine
* example-storage-engine::       The `EXAMPLE' Storage Engine
* federated-storage-engine::     The `FEDERATED' Storage Engine
* archive-storage-engine::       The `ARCHIVE' Storage Engine
* csv-storage-engine::           The `CSV' Storage Engine
* blackhole-storage-engine::     The `BLACKHOLE' Storage Engine

MySQL supports several storage engines that act as handlers for
different table types. MySQL storage engines include both those that
handle transaction-safe tables and those that handle
non-transaction-safe tables.

With MySQL 5.1, MySQL AB has introduced a new pluggable storage engine
architecture that allows storage engines to be loaded into and unloaded
from a running MySQL server.

To determine which storage engines your server supports by using the
*Note `SHOW ENGINES': show-engines. statement. The value in the
`Support' column indicates whether an engine can be used. A value of
`YES', `NO', or `DEFAULT' indicates that an engine is available, not
available, or avaiable and current set as the default storage engine.

     mysql> SHOW ENGINES\G
     *************************** 1. row ***************************
           Engine: FEDERATED
          Support: NO
          Comment: Federated MySQL storage engine
     Transactions: NULL
               XA: NULL
       Savepoints: NULL
     *************************** 2. row ***************************
           Engine: MRG_MYISAM
          Support: YES
          Comment: Collection of identical MyISAM tables
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 3. row ***************************
           Engine: MyISAM
          Support: DEFAULT
          Comment: Default engine as of MySQL 3.23 with great performance
     Transactions: NO
               XA: NO
       Savepoints: NO
     ...

This chapter describes each of the MySQL storage engines except for
`NDBCLUSTER', which is covered in MySQL Cluster NDB 6.X/7.X
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html). It also
contains a description of the pluggable storage engine architecture (see
*Note pluggable-storage-overview::).

For information about storage engine support offered in commercial
MySQL Server binaries, see `MySQL Enterprise Server 5.1'
(http://www.mysql.com/products/enterprise/server.html), on the MySQL
website. The storage engines available might depend on which edition of
Enterprise Server you are using.

For answers to some commonly asked questions about MySQL storage
engines, see *Note faqs-storage-engines::.

*MySQL 6.0 supported storage engines:*

   * *Note `MyISAM': myisam-storage-engine.  -- The default MySQL
     storage engine and the one that is used the most in Web, data
     warehousing, and other application environments. `MyISAM' is
     supported in all MySQL configurations, and is the default storage
     engine unless you have configured MySQL to use a different one by
     default.

   * *Note `InnoDB': innodb. -- A transaction-safe (ACID compliant)
     storage engine for MySQL that has commit, rollback, and
     crash-recovery capabilities to protect user data. `InnoDB'
     row-level locking (without escalation to coarser granularity
     locks) and Oracle-style consistent non-locking reads increase
     multi-user concurrency and performance. `InnoDB' stores user data
     in clustered indexes to reduce I/O for common queries based on
     primary keys. To maintain data integrity, `InnoDB' also supports
     `FOREIGN KEY' referential-integrity constraints.

   * *Note `Falcon': se-falcon.  -- Designed with modern database
     requirements in mind, and particularly for use within high-volume
     web serving or other environment that requires high performance,
     while still supporting the transactional and logging functionality
     required in this environment. Multi Version Concurrency Control
     (MVCC) enables records and tables to be updated without the
     overhead associated with row-level locking mechanisms.  `Falcon'
     is transaction-safe (fully ACID-compliant) and able to handle
     multiple concurrent transactions.

   * *Note `Maria': se-maria. -- A crash safe version of `MyISAM'. The
     `Maria' storage engine supports all of the main functionality of
     the `MyISAM' engine, but includes recovery support (in the event
     of a system crash), full logging (including `CREATE', `DROP',
     `RENAME' and *Note `TRUNCATE': truncate. operations), all `MyISAM'
     row formats and a new `Maria' specific row format.

   * *Note `Memory': memory-storage-engine.  -- Stores all data in RAM
     for extremely fast access in environments that require quick
     lookups of reference and other like data. This engine was formerly
     known as the `HEAP' engine.

   * *Note `Merge': merge-storage-engine.  -- Allows a MySQL DBA or
     developer to logically group a series of identical `MyISAM' tables
     and reference them as one object. Good for VLDB environments such
     as data warehousing.

   * *Note `Archive': archive-storage-engine.  -- Provides the perfect
     solution for storing and retrieving large amounts of
     seldom-referenced historical, archived, or security audit
     information.

   * *Note `Federated': federated-storage-engine.  -- Offers the
     ability to link separate MySQL servers to create one logical
     database from many physical servers. Very good for distributed or
     data mart environments.

   * *Note `CSV': csv-storage-engine.  -- The CSV storage engine stores
     data in text files using comma-separated values format. You can
     use the CSV engine to easily exchange data between other software
     and applications that can import and export in CSV format.

   * *Note `Blackhole': blackhole-storage-engine.  -- The Blackhole
     storage engine accepts but does not store data and retrievals
     always return an empty set. The functionality can be used in
     distributed database design where data is automatically
     replicated, but not stored locally.

   * *Note `Example': example-storage-engine.  -- The Example storage
     engine is `stub' engine that does nothing. You can create tables
     with this engine, but no data can be stored in them or retrieved
     from them. The purpose of this engine is to serve as an example in
     the MySQL source code that illustrates how to begin writing new
     storage engines. As such, it is primarily of interest to
     developers.

This chapter describes each of the MySQL storage engines except for
`NDBCLUSTER', which is covered in MySQL Cluster NDB 6.X/7.X
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html).

*Note*:

The `NDBCLUSTER' storage engine is currently not supported in MySQL
6.0. `NDB' users wishing to upgrade from MySQL 5.0 or 5.1 should
instead migrate to MySQL Cluster NDB 6.2 or 6.3; these are based on
MySQL 5.1 but contain the latest improvements and fixes for
`NDBCLUSTER'.

It is important to remember that you are not restricted to using the
same storage engine for an entire server or schema: you can use a
different storage engine for each table in your schema.

*Choosing a Storage Engine*

The various storage engines provided with MySQL are designed with
different use-cases in mind. To use the pluggable storage architecture
effectively, it is good to have an idea of the advantages and
disadvantages of the various storage engines. The following table
provides an overview of some storage engines provided with MySQL:

*Storage Engine Features*

Feature MyISAM       Memory       InnoDB       Archive      Falcon
Storage 256TB        RAM          64TB         None         512ZB
limits                                                      
TransactionsNo           No           Yes          No           Yes
Locking Table        Table        Row          Row          Row
granularity                                                    
MVCC    No           No           Yes          No           Yes
GeospatialYes          No           Yes          Yes          No
datatype                                                    
support                                                     
GeospatialYes          No           No           No           No
indexing                                                    
support                                                     
B-tree  Yes          Yes          Yes          No           Yes
indexes                                                     
Hash    No           Yes          No           No           No
indexes                                                     
Full-textYes          No           No           No           No
search                                                      
indexes                                                     
ClusteredNo           No           Yes          No           No
indexes                                                     
Data    No           N/A          Yes          No           Yes
caches                                                      
Index   Yes          N/A          Yes          No           Yes
caches                                                      
CompressedYes          No           Yes          Yes          Yes
data    Compressed                Compressed                
        MyISAM                    InnoDB                    
        tables are                tables are                
        supported                 supported                 
        only when                 only by                   
        using the                 InnoDB                    
        compressed                Plugin.                   
        row format.                                         
        Tables                                              
        using the                                           
        compressed                                          
        row format                                          
        with MyISAM                                         
        are read                                            
        only.                                               
EncryptedYes          Yes          Yes          Yes          Yes
data                                                        
Implemented                                                    
in the                                                      
server                                                      
(via                                                        
encryption                                                    
functions),                                                    
rather                                                      
than                                                        
in the                                                      
storage                                                     
engine.                                                     
Cluster No           No           No           No           No
database                                                    
support                                                     
ReplicationYes          Yes          Yes          Yes          Yes
support                                                     
Implemented                                                    
in the                                                      
server,                                                     
rather                                                      
than                                                        
in the                                                      
storage                                                     
engine                                                      
Foreign No           No           Yes          No           No
key                                                         
support                                                     
Backup  Yes          Yes          Yes          Yes          Yes
/                                                           
point-in-time                                                    
recovery                                                    
Implemented                                                    
in the                                                      
server,                                                     
rather                                                      
than                                                        
in the                                                      
storage                                                     
engine                                                      
Query   Yes          Yes          Yes          Yes          Yes
cache                                                       
support                                                     
Update  Yes          Yes          Yes          Yes          Yes
statistics                                                    
for                                                         
data                                                        
dictionary                                                    


File: manual.info,  Node: storage-engine-compare-transactions,  Next: storage-engines-other,  Prev: storage-engines,  Up: storage-engines

13.1 Comparing Transaction and Non-Transaction Engines
======================================================

Transaction-safe tables (TSTs) have several advantages over
non-transaction-safe tables (NTSTs):

   * They are safer. Even if MySQL crashes or you get hardware
     problems, you can get your data back, either by automatic recovery
     or from a backup plus the transaction log.

   * You can combine many statements and accept them all at the same
     time with the *Note `COMMIT': commit.  statement (if autocommit is
     disabled).

   * You can execute *Note `ROLLBACK': commit. to ignore your changes
     (if autocommit is disabled).

   * If an update fails, all of your changes are reverted. (With
     non-transaction-safe tables, all changes that have taken place are
     permanent.)

   * Transaction-safe storage engines can provide better concurrency
     for tables that get many updates concurrently with reads.

You can combine transaction-safe and non-transaction-safe tables in the
same statements to get the best of both worlds. However, although MySQL
supports several transaction-safe storage engines, for best results,
you should not mix different storage engines within a transaction with
autocommit disabled. For example, if you do this, changes to
non-transaction-safe tables still are committed immediately and cannot
be rolled back. For information about this and other problems that can
occur in transactions that use mixed storage engines, see *Note
commit::.

Non-transaction-safe tables have several advantages of their own, all
of which occur because there is no transaction overhead:

   * Much faster

   * Lower disk space requirements

   * Less memory required to perform updates


File: manual.info,  Node: storage-engines-other,  Next: storage-engine-setting,  Prev: storage-engine-compare-transactions,  Up: storage-engines

13.2 Other Storage Engines
==========================

Other storage engines may be available from third parties and community
members that have used the Custom Storage Engine interface.

You can find more information on the list of third party storage
engines on the MySQL Forge Storage Engines
(http://forge.mysql.com/projects/search.php?t=tag&k=storage%20engine)
page.

*Note*:

Third party engines are not supported by MySQL. For further
information, documentation, installation guides, bug reporting or for
any help or assistance with these engines, please contact the developer
of the engine directly.

Third party engines that are known to be available include the
following; please see the MySQL Forge links provided for more
information:

   * *PrimeBase XT (PBXT)
     (http://forge.mysql.com/projects/project.php?id=43)* -- PBXT has
     been designed for modern, web-based, high concurrency environments.

   * *RitmarkFS (http://forge.mysql.com/projects/project.php?id=82)* --
     RitmarkFS allows you to access and manipulate the file system
     using SQL queries. RitmarkFS also supports file system replication
     and directory change tracking.

   * *Distributed Data Engine
     (http://forge.mysql.com/projects/project.php?id=91)* -- The
     Distributed Data Engine is an Open Source project that is
     dedicated to provide a Storage Engine for distributed data
     according to workload statistics.

   * *mdbtools (http://forge.mysql.com/projects/project.php?id=98)* --
     A pluggable storage engine that allows read-only access to
     Microsoft Access `.mdb' database files.

   * *solidDB for MySQL
     (http://forge.mysql.com/projects/project.php?id=139)* -- solidDB
     Storage Engine for MySQL is an open source, transactional storage
     engine for MySQL Server. It is designed for mission-critical
     implementations that require a robust, transactional database.
     solidDB Storage Engine for MySQL is a multi-threaded storage
     engine that supports full ACID compliance with all expected
     transaction isolation levels, row-level locking, and Multi-Version
     Concurrency Control (MVCC) with non-blocking reads and writes.

   * *BLOB Streaming Engine (MyBS) (http://www.blobstreaming.org/)* --
     The Scalable BLOB Streaming infrastructure for MySQL will
     transform MySQL into a scalable media server capable of streaming
     pictures, films, MP3 files and other binary and text objects
     (BLOBs) directly in and out of the database.

For more information on developing a customer storage engine that can
be used with the Pluggable Storage Engine Architecture, see Writing a
Custom Storage Engine
(http://forge.mysql.com/wiki/MySQL_Internals_Custom_Engine) on MySQL
Forge (http://forge.mysql.com/wiki).


File: manual.info,  Node: storage-engine-setting,  Next: pluggable-storage-overview,  Prev: storage-engines-other,  Up: storage-engines

13.3 Setting the Storage Engine
===============================

When you create a new table, you can specify which storage engine to
use by adding an `ENGINE' table option to the *Note `CREATE TABLE':
create-table. statement:

     CREATE TABLE t (i INT) ENGINE = INNODB;

If you omit the `ENGINE' or `TYPE' option, the default storage engine is
used. Normally, this is `MyISAM', but you can change it by using the
`--default-storage-engine' or `--default-table-type' server startup
option, or by setting the `default-storage-engine' or
`default-table-type' option in the `my.cnf' configuration file.

You can set the default storage engine to be used during the current
session by setting the `storage_engine' variable:

     SET storage_engine=MYISAM;

When MySQL is installed on Windows using the MySQL Configuration
Wizard, the `InnoDB' storage engine can be selected as the default
instead of `MyISAM'. See *Note mysql-config-wizard-database-usage::.

To convert a table from one storage engine to another, use an *Note
`ALTER TABLE': alter-table. statement that indicates the new engine:

     ALTER TABLE t ENGINE = MYISAM;

See *Note create-table::, and *Note alter-table::.

If you try to use a storage engine that is not compiled in or that is
compiled in but deactivated, MySQL instead creates a table using the
default storage engine, usually `MyISAM'. This behavior is convenient
when you want to copy tables between MySQL servers that support
different storage engines. (For example, in a replication setup, perhaps
your master server supports transactional storage engines for increased
safety, but the slave servers use only non-transactional storage
engines for greater speed.)

This automatic substitution of the default storage engine for
unavailable engines can be confusing for new MySQL users. A warning is
generated whenever a storage engine is automatically changed.

For new tables, MySQL always creates an `.frm' file to hold the table
and column definitions. The table's index and data may be stored in one
or more other files, depending on the storage engine. The server
creates the `.frm' file above the storage engine level.  Individual
storage engines create any additional files required for the tables
that they manage. If a table name contains special characters, the
names for the table files contain encoded versions of those characters
as described in *Note identifier-mapping::.

A database may contain tables of different types. That is, tables need
not all be created with the same storage engine.


File: manual.info,  Node: pluggable-storage-overview,  Next: myisam-storage-engine,  Prev: storage-engine-setting,  Up: storage-engines

13.4 Overview of MySQL Storage Engine Architecture
==================================================

* Menu:

* pluggable-storage-common-layer::  The Common Database Server Layer
* pluggable-storage::            Pluggable Storage Engine Architecture

The MySQL pluggable storage engine architecture allows a database
professional to select a specialized storage engine for a particular
application need while being completely shielded from the need to
manage any specific application coding requirements.  The MySQL server
architecture isolates the application programmer and DBA from all of
the low-level implementation details at the storage level, providing a
consistent and easy application model and API. Thus, although there are
different capabilities across different storage engines, the
application is shielded from these differences.

The MySQL pluggable storage engine architecture is shown in *Note
figure-storage-engine-architecture::.

FIGURE GOES HERE: The MySQL architecture using pluggable storage engines

The pluggable storage engine architecture provides a standard set of
management and support services that are common among all underlying
storage engines. The storage engines themselves are the components of
the database server that actually perform actions on the underlying
data that is maintained at the physical server level.

This efficient and modular architecture provides huge benefits for
those wishing to specifically target a particular application need --
such as data warehousing, transaction processing, or high availability
situations -- while enjoying the advantage of utilizing a set of
interfaces and services that are independent of any one storage engine.

The application programmer and DBA interact with the MySQL database
through Connector APIs and service layers that are above the storage
engines. If application changes bring about requirements that demand
the underlying storage engine change, or that one or more additional
storage engines be added to support new needs, no significant coding or
process changes are required to make things work. The MySQL server
architecture shields the application from the underlying complexity of
the storage engine by presenting a consistent and easy-to-use API that
applies across storage engines.


File: manual.info,  Node: pluggable-storage-common-layer,  Next: pluggable-storage,  Prev: pluggable-storage-overview,  Up: pluggable-storage-overview

13.4.1 The Common Database Server Layer
---------------------------------------

A MySQL pluggable storage engine is the component in the MySQL database
server that is responsible for performing the actual data I/O
operations for a database as well as enabling and enforcing certain
feature sets that target a specific application need. A major benefit
of using specific storage engines is that you are only delivered the
features needed for a particular application, and therefore you have
less system overhead in the database, with the end result being more
efficient and higher database performance. This is one of the reasons
that MySQL has always been known to have such high performance,
matching or beating proprietary monolithic databases in industry
standard benchmarks.

From a technical perspective, what are some of the unique supporting
infrastructure components that are in a storage engine? Some of the key
feature differentiations include:

   * _Concurrency_ -- some applications have more granular lock
     requirements (such as row-level locks) than others. Choosing the
     right locking strategy can reduce overhead and therefore improve
     overall performance.  This area also includes support for
     capabilities such as multi-version concurrency control or
     `snapshot' read.

   * _Transaction Support_ -- Not every application needs transactions,
     but for those that do, there are very well defined requirements
     such as ACID compliance and more.

   * _Referential Integrity_ -- The need to have the server enforce
     relational database referential integrity through DDL defined
     foreign keys.

   * _Physical Storage_ -- This involves everything from the overall
     page size for tables and indexes as well as the format used for
     storing data to physical disk.

   * _Index Support_ -- Different application scenarios tend to benefit
     from different index strategies. Each storage engine generally has
     its own indexing methods, although some (such as B-tree indexes)
     are common to nearly all engines.

   * _Memory Caches_ -- Different applications respond better to some
     memory caching strategies than others, so although some memory
     caches are common to all storage engines (such as those used for
     user connections or MySQL's high-speed Query Cache), others are
     uniquely defined only when a particular storage engine is put in
     play.

   * _Performance Aids_ -- This includes multiple I/O threads for
     parallel operations, thread concurrency, database checkpointing,
     bulk insert handling, and more.

   * _Miscellaneous Target Features_ -- This may include support for
     geospatial operations, security restrictions for certain data
     manipulation operations, and other similar features.

Each set of the pluggable storage engine infrastructure components are
designed to offer a selective set of benefits for a particular
application. Conversely, avoiding a set of component features helps
reduce unnecessary overhead. It stands to reason that understanding a
particular application's set of requirements and selecting the proper
MySQL storage engine can have a dramatic impact on overall system
efficiency and performance.


File: manual.info,  Node: pluggable-storage,  Prev: pluggable-storage-common-layer,  Up: pluggable-storage-overview

13.4.2 Pluggable Storage Engine Architecture
--------------------------------------------

* Menu:

* pluggable-storage-plugging::   Plugging in a Storage Engine
* pluggable-storage-unplugging::  Unplugging a Storage Engine
* pluggable-storage-security::   Security Implications of Pluggable Storage

With MySQL 5.1, MySQL AB has introduced a new pluggable storage engine
architecture that allows storage engines to be loaded into and unloaded
from a running MySQL server.


File: manual.info,  Node: pluggable-storage-plugging,  Next: pluggable-storage-unplugging,  Prev: pluggable-storage,  Up: pluggable-storage

13.4.2.1 Plugging in a Storage Engine
.....................................

Before a storage engine can be used, the storage engine plugin shared
library must be loaded into MySQL using the *Note `INSTALL PLUGIN':
install-plugin. statement. For example, if the `EXAMPLE' engine plugin
is named `ha_example' and the shared library is named `ha_example.so',
you load it with the following statement:

     INSTALL PLUGIN ha_example SONAME 'ha_example.so';

The shared library must be located in the MySQL server plugin
directory, the location of which is given by the `plugin_dir' system
variable.


File: manual.info,  Node: pluggable-storage-unplugging,  Next: pluggable-storage-security,  Prev: pluggable-storage-plugging,  Up: pluggable-storage

13.4.2.2 Unplugging a Storage Engine
....................................

To unplug a storage engine, use the *Note `UNINSTALL PLUGIN':
uninstall-plugin. statement:

     UNINSTALL PLUGIN ha_example;

If you unplug a storage engine that is needed by existing tables, those
tables become inaccessible, but will still be present on disk (where
applicable). Ensure that there are no tables using a storage engine
before you unplug the storage engine.


File: manual.info,  Node: pluggable-storage-security,  Prev: pluggable-storage-unplugging,  Up: pluggable-storage

13.4.2.3 Security Implications of Pluggable Storage
...................................................

To install a pluggable storage engine, the plugin file must be located
in the MySQL plugin directory, and the user issuing the *Note `INSTALL
PLUGIN': install-plugin. statement must have the `INSERT' privilege for
the `mysql.plugin' table.


File: manual.info,  Node: myisam-storage-engine,  Next: se-maria,  Prev: pluggable-storage-overview,  Up: storage-engines

13.5 The `MyISAM' Storage Engine
================================

* Menu:

* myisam-start::                 `MyISAM' Startup Options
* key-space::                    Space Needed for Keys
* myisam-table-formats::         `MyISAM' Table Storage Formats
* myisam-table-problems::        `MyISAM' Table Problems

`MyISAM' is the default storage engine. It is based on the older `ISAM'
code but has many useful extensions. (Note that MySQL 6.0 does _not_
support `ISAM'.)

*MyISAM Features*

*Storage limits* 256TB    *Transactions*   No       *Locking         Table
                                                    granularity*     
*MVCC*           No       *Geospatial      Yes      *Geospatial      Yes
                          datatype                  indexing         
                          support*                  support*         
*B-tree indexes* Yes      *Hash indexes*   No       *Full-text       Yes
                                                    search indexes*  
*Clustered       No       *Data caches*    No       *Index caches*   Yes
indexes*                                                             
*Compressed      Yes      *Encrypted data  Yes      *Cluster         No
data*            CompressedImplemented in            database         
                 MyISAM   the server (via           support*         
                 tables   encryption                                 
                 are      functions),                                
                 supportedrather than in                             
                 only     the storage                                
                 when     engine.*                                   
                 using                                               
                 the                                                 
                 compressed                                           
                 row                                                 
                 format.                                             
                 Tables                                              
                 using                                               
                 the                                                 
                 compressed                                           
                 row                                                 
                 format                                              
                 with                                                
                 MyISAM                                              
                 are                                                 
                 read                                                
                 only.                                               
*Replication     Yes      *Foreign key     No       *Backup /        Yes
support                   support*                  point-in-time    
Implemented in                                      recovery         
the server,                                         Implemented in   
rather than in                                      the server,      
the storage                                         rather than in   
engine*                                             the storage      
                                                    engine*          
*Query cache     Yes      *Update          Yes                       
support*                  statistics for                             
                          data dictionary*                           

Each `MyISAM' table is stored on disk in three files. The files have
names that begin with the table name and have an extension to indicate
the file type. An `.frm' file stores the table format. The data file
has an `.MYD' (`MYData') extension. The index file has an `.MYI'
(`MYIndex') extension.

To specify explicitly that you want a `MyISAM' table, indicate that
with an `ENGINE' table option:

     CREATE TABLE t (i INT) ENGINE = MYISAM;

Normally, it is unnecesary to use `ENGINE' to specify the `MyISAM'
storage engine.  `MyISAM' is the default engine unless the default has
been changed. To ensure that `MyISAM' is used in situations where the
default might have been changed, include the `ENGINE' option explicitly.

You can check or repair `MyISAM' tables with the *Note `mysqlcheck':
mysqlcheck. client or *Note `myisamchk': myisamchk.  utility. You can
also compress `MyISAM' tables with *Note `myisampack': myisampack. to
take up much less space. See *Note mysqlcheck::, *Note
crash-recovery::, and *Note myisampack::.

`MyISAM' tables have the following characteristics:

   * All data values are stored with the low byte first. This makes the
     data machine and operating system independent. The only
     requirements for binary portability are that the machine uses
     two's-complement signed integers and IEEE floating-point format.
     These requirements are widely used among mainstream machines.
     Binary compatibility might not be applicable to embedded systems,
     which sometimes have peculiar processors.

     There is no significant speed penalty for storing data low byte
     first; the bytes in a table row normally are unaligned and it
     takes little more processing to read an unaligned byte in order
     than in reverse order. Also, the code in the server that fetches
     column values is not time critical compared to other code.

   * All numeric key values are stored with the high byte first to
     allow better index compression.

   * Large files (up to 63-bit file length) are supported on file
     systems and operating systems that support large files.

   * There is a limit of 2^32 (~4.295E+09) rows in a `MyISAM' table. If
     you build MySQL with the `--with-big-tables' option, the row
     limitation is increased to (2^32)^2 (1.844E+19) rows. See *Note
     configure-options::.  Binary distributions for Unix and Linux are
     built with this option.

   * The maximum number of indexes per `MyISAM' table is 64. This can
     be changed by recompiling. You can configure the build by invoking
     `configure' with the `--with-max-indexes=N' option, where N is the
     maximum number of indexes to permit per `MyISAM' table.  N must be
     less than or equal to 128.

     The maximum number of columns per index is 16.

   * The maximum key length is 1000 bytes. This can also be changed by
     changing the source and recompiling. For the case of a key longer
     than 250 bytes, a larger key block size than the default of 1024
     bytes is used.

   * When rows are inserted in sorted order (as when you are using an
     `AUTO_INCREMENT' column), the index tree is split so that the high
     node only contains one key. This improves space utilization in the
     index tree.

   * Internal handling of one `AUTO_INCREMENT' column per table is
     supported. `MyISAM' automatically updates this column for *Note
     `INSERT': insert. and *Note `UPDATE': update. operations. This
     makes `AUTO_INCREMENT' columns faster (at least 10%).  Values at
     the top of the sequence are not reused after being deleted. (When
     an `AUTO_INCREMENT' column is defined as the last column of a
     multiple-column index, reuse of values deleted from the top of a
     sequence does occur.) The `AUTO_INCREMENT' value can be reset with
     *Note `ALTER TABLE': alter-table. or *Note `myisamchk': myisamchk.

   * Dynamic-sized rows are much less fragmented when mixing deletes
     with updates and inserts. This is done by automatically combining
     adjacent deleted blocks and by extending blocks if the next block
     is deleted.

   * `MyISAM' supports concurrent inserts: If a table has no free
     blocks in the middle of the data file, you can *Note `INSERT':
     insert. new rows into it at the same time that other threads are
     reading from the table. A free block can occur as a result of
     deleting rows or an update of a dynamic length row with more data
     than its current contents.  When all free blocks are used up
     (filled in), future inserts become concurrent again. See *Note
     concurrent-inserts::.

   * You can put the data file and index file in different directories
     on different physical devices to get more speed with the `DATA
     DIRECTORY' and `INDEX DIRECTORY' table options to *Note `CREATE
     TABLE': create-table. See *Note create-table::.

   * *Note `BLOB': blob. and *Note `TEXT': blob. columns can be indexed.

   * `NULL' values are allowed in indexed columns.  This takes 0-1
     bytes per key.

   * Each character column can have a different character set. See
     *Note charset::.

   * There is a flag in the `MyISAM' index file that indicates whether
     the table was closed correctly. If *Note `mysqld': mysqld. is
     started with the `--myisam-recover' option, `MyISAM' tables are
     automatically checked when opened, and are repaired if the table
     wasn't closed properly.

   * *Note `myisamchk': myisamchk. marks tables as checked if you run
     it with the `--update-state' option. *Note `myisamchk --fast':
     myisamchk. checks only those tables that don't have this mark.

   * *Note `myisamchk --analyze': myisamchk. stores statistics for
     portions of keys, as well as for entire keys.

   * *Note `myisampack': myisampack. can pack *Note `BLOB': blob. and
     *Note `VARCHAR': char. columns.

`MyISAM' also supports the following features:

   * Support for a true *Note `VARCHAR': char. type; a *Note `VARCHAR':
     char. column starts with a length stored in one or two bytes.

   * Tables with *Note `VARCHAR': char. columns may have fixed or
     dynamic row length.

   * The sum of the lengths of the *Note `VARCHAR': char. and *Note
     `CHAR': char. columns in a table may be up to 64KB.

   * Arbitrary length `UNIQUE' constraints.

*Additional resources*

   * A forum dedicated to the `MyISAM' storage engine is available at
     `http://forums.mysql.com/list.php?21'.


File: manual.info,  Node: myisam-start,  Next: key-space,  Prev: myisam-storage-engine,  Up: myisam-storage-engine

13.5.1 `MyISAM' Startup Options
-------------------------------

The following options to *Note `mysqld': mysqld. can be used to change
the behavior of `MyISAM' tables. For additional information, see *Note
server-options::.

*`mysqld' MyISAM Option/Variable Reference*

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
bulk_insert_buffer_size       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
concurrent_insert             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
delay-key-write               Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: delay_key_write                                                                                                                       Yes                                                                                                                   Global                                                     Yes
have_rtree_keys                                                                                                                                     Yes                                                                                                                   Global                                                     No
key_buffer_size               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
log-isam                      Yes                                                        Yes                                                                                                                                                                                                                                         
myisam-block-size             Yes                                                        Yes                                                                                                                                                                                                                                         
myisam_data_pointer_size      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
myisam_max_sort_file_size     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
myisam-recover                Yes                                                        Yes                                                                                                                                                                                                                                         
myisam_recover_options                                                                                                                              Yes                                                                                                                   Global                                                     No
myisam_repair_threads         Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_sort_buffer_size       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_stats_method           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_use_mmap               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
skip-concurrent-insert        Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_:                                                                                                                                                                                                                                                                                                                        
concurrent_insert                                                                                                                                                                                                                                                                                                                    
tmp_table_size                Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes

   * `--myisam-recover=MODE'

     Set the mode for automatic recovery of crashed `MyISAM' tables.

   * `--delay-key-write=ALL'

     Don't flush key buffers between writes for any `MyISAM' table.

     *Note*:

     If you do this, you should not access `MyISAM' tables from another
     program (such as from another MySQL server or with *Note
     `myisamchk': myisamchk.) when the tables are in use.  Doing so
     risks index corruption. Using `--external-locking' does not
     eliminate this risk.

The following system variables affect the behavior of `MyISAM' tables.
For additional information, see *Note server-system-variables::.

   * `bulk_insert_buffer_size'

     The size of the tree cache used in bulk insert optimization.

     *Note*:

     This is a limit _per thread_!

   * `myisam_max_sort_file_size'

     The maximum size of the temporary file that MySQL is allowed to
     use while re-creating a `MyISAM' index (during *Note `REPAIR
     TABLE': repair-table, *Note `ALTER TABLE': alter-table, or *Note
     `LOAD DATA INFILE': load-data.). If the file size would be larger
     than this value, the index is created using the key cache instead,
     which is slower. The value is given in bytes.

   * `myisam_sort_buffer_size'

     Set the size of the buffer used when recovering tables.

Automatic recovery is activated if you start *Note `mysqld': mysqld.
with the `--myisam-recover' option. In this case, when the server opens
a `MyISAM' table, it checks whether the table is marked as crashed or
whether the open count variable for the table is not 0 and you are
running the server with external locking disabled. If either of these
conditions is true, the following happens:

   * The server checks the table for errors.

   * If the server finds an error, it tries to do a fast table repair
     (with sorting and without re-creating the data file).

   * If the repair fails because of an error in the data file (for
     example, a duplicate-key error), the server tries again, this time
     re-creating the data file.

   * If the repair still fails, the server tries once more with the old
     repair option method (write row by row without sorting).  This
     method should be able to repair any type of error and has low disk
     space requirements.

MySQL Enterprise

Subscribers to MySQL Enterprise Monitor receive notification if the
`--myisam-recover' option has not been set. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

If the recovery wouldn't be able to recover all rows from previously
completed statements and you didn't specify `FORCE' in the value of the
`--myisam-recover' option, automatic repair aborts with an error
message in the error log:

     Error: Couldn't repair table: test.g00pages

If you specify `FORCE', a warning like this is written instead:

     Warning: Found 344 of 354 rows when repairing ./test/g00pages

Note that if the automatic recovery value includes `BACKUP', the
recovery process creates files with names of the form
`TBL_NAME-DATETIME.BAK'.  You should have a `cron' script that
automatically moves these files from the database directories to backup
media.


File: manual.info,  Node: key-space,  Next: myisam-table-formats,  Prev: myisam-start,  Up: myisam-storage-engine

13.5.2 Space Needed for Keys
----------------------------

`MyISAM' tables use B-tree indexes. You can roughly calculate the size
for the index file as `(key_length+4)/0.67', summed over all keys. This
is for the worst case when all keys are inserted in sorted order and
the table doesn't have any compressed keys.

String indexes are space compressed. If the first index part is a
string, it is also prefix compressed. Space compression makes the index
file smaller than the worst-case figure if a string column has a lot of
trailing space or is a *Note `VARCHAR': char. column that is not always
used to the full length. Prefix compression is used on keys that start
with a string. Prefix compression helps if there are many strings with
an identical prefix.

In `MyISAM' tables, you can also prefix compress numbers by specifying
the `PACK_KEYS=1' table option when you create the table. Numbers are
stored with the high byte first, so this helps when you have many
integer keys that have an identical prefix.


File: manual.info,  Node: myisam-table-formats,  Next: myisam-table-problems,  Prev: key-space,  Up: myisam-storage-engine

13.5.3 `MyISAM' Table Storage Formats
-------------------------------------

* Menu:

* static-format::                Static (Fixed-Length) Table Characteristics
* dynamic-format::               Dynamic Table Characteristics
* compressed-format::            Compressed Table Characteristics

`MyISAM' supports three different storage formats. Two of them, fixed
and dynamic format, are chosen automatically depending on the type of
columns you are using. The third, compressed format, can be created
only with the *Note `myisampack': myisampack. utility (see *Note
myisampack::).

When you use *Note `CREATE TABLE': create-table. or *Note `ALTER
TABLE': alter-table. for a table that has no *Note `BLOB': blob. or
*Note `TEXT': blob. columns, you can force the table format to *Note
`FIXED': numeric-types. or `DYNAMIC' with the `ROW_FORMAT' table option.

See *Note create-table::, for information about `ROW_FORMAT'.

You can decompress (unpack) compressed `MyISAM' tables using *Note
`myisamchk `--unpack'': myisamchk.; see *Note myisamchk::, for more
information.


File: manual.info,  Node: static-format,  Next: dynamic-format,  Prev: myisam-table-formats,  Up: myisam-table-formats

13.5.3.1 Static (Fixed-Length) Table Characteristics
....................................................

Static format is the default for `MyISAM' tables. It is used when the
table contains no variable-length columns (*Note `VARCHAR': char, *Note
`VARBINARY': binary-varbinary, *Note `BLOB': blob, or *Note `TEXT':
blob.). Each row is stored using a fixed number of bytes.

Of the three `MyISAM' storage formats, static format is the simplest
and most secure (least subject to corruption). It is also the fastest
of the on-disk formats due to the ease with which rows in the data file
can be found on disk: To look up a row based on a row number in the
index, multiply the row number by the row length to calculate the row
position. Also, when scanning a table, it is very easy to read a
constant number of rows with each disk read operation.

The security is evidenced if your computer crashes while the MySQL
server is writing to a fixed-format `MyISAM' file. In this case, *Note
`myisamchk': myisamchk. can easily determine where each row starts and
ends, so it can usually reclaim all rows except the partially written
one. Note that `MyISAM' table indexes can always be reconstructed based
on the data rows.

*Note*:

Fixed-length row format is only available for tables without *Note
`BLOB': blob. or *Note `TEXT': blob. columns. Creating a table with
these columns with an explicit `ROW_FORMAT' clause will not raise an
error or warning; the format specification will be ignored.

Static-format tables have these characteristics:

   * *Note `CHAR': char. and *Note `VARCHAR': char. columns are
     space-padded to the specified column width, although the column
     type is not altered.  *Note `BINARY': binary-varbinary. and *Note
     `VARBINARY': binary-varbinary. columns are padded with `0x00'
     bytes to the column width.

   * Very quick.

   * Easy to cache.

   * Easy to reconstruct after a crash, because rows are located in
     fixed positions.

   * Reorganization is unnecessary unless you delete a huge number of
     rows and want to return free disk space to the operating system.
     To do this, use *Note `OPTIMIZE TABLE': optimize-table. or *Note
     `myisamchk -r': myisamchk.

   * Usually require more disk space than dynamic-format tables.


File: manual.info,  Node: dynamic-format,  Next: compressed-format,  Prev: static-format,  Up: myisam-table-formats

13.5.3.2 Dynamic Table Characteristics
......................................

Dynamic storage format is used if a `MyISAM' table contains any
variable-length columns (*Note `VARCHAR': char, *Note `VARBINARY':
binary-varbinary, *Note `BLOB': blob, or *Note `TEXT': blob.), or if
the table was created with the `ROW_FORMAT=DYNAMIC' table option.

Dynamic format is a little more complex than static format because each
row has a header that indicates how long it is. A row can become
fragmented (stored in non-contiguous pieces) when it is made longer as
a result of an update.

You can use *Note `OPTIMIZE TABLE': optimize-table. or *Note `myisamchk
-r': myisamchk. to defragment a table. If you have fixed-length columns
that you access or change frequently in a table that also contains some
variable-length columns, it might be a good idea to move the
variable-length columns to other tables just to avoid fragmentation.

Dynamic-format tables have these characteristics:

   * All string columns are dynamic except those with a length less
     than four.

   * Each row is preceded by a bitmap that indicates which columns
     contain the empty string (for string columns) or zero (for numeric
     columns). Note that this does not include columns that contain
     `NULL' values. If a string column has a length of zero after
     trailing space removal, or a numeric column has a value of zero,
     it is marked in the bitmap and not saved to disk. Non-empty
     strings are saved as a length byte plus the string contents.

   * Much less disk space usually is required than for fixed-length
     tables.

   * Each row uses only as much space as is required. However, if a row
     becomes larger, it is split into as many pieces as are required,
     resulting in row fragmentation. For example, if you update a row
     with information that extends the row length, the row becomes
     fragmented. In this case, you may have to run *Note `OPTIMIZE
     TABLE': optimize-table. or *Note `myisamchk -r': myisamchk. from
     time to time to improve performance. Use *Note `myisamchk -ei':
     myisamchk. to obtain table statistics.

   * More difficult than static-format tables to reconstruct after a
     crash, because rows may be fragmented into many pieces and links
     (fragments) may be missing.

   * The expected row length for dynamic-sized rows is calculated using
     the following expression:

          3
          + (NUMBER OF COLUMNS + 7) / 8
          + (NUMBER OF CHAR COLUMNS)
          + (PACKED SIZE OF NUMERIC COLUMNS)
          + (LENGTH OF STRINGS)
          + (NUMBER OF NULL COLUMNS + 7) / 8

     There is a penalty of 6 bytes for each link. A dynamic row is
     linked whenever an update causes an enlargement of the row. Each
     new link is at least 20 bytes, so the next enlargement probably
     goes in the same link. If not, another link is created. You can
     find the number of links using *Note `myisamchk -ed': myisamchk.
     All links may be removed with *Note `OPTIMIZE TABLE':
     optimize-table. or *Note `myisamchk -r': myisamchk.


File: manual.info,  Node: compressed-format,  Prev: dynamic-format,  Up: myisam-table-formats

13.5.3.3 Compressed Table Characteristics
.........................................

Compressed storage format is a read-only format that is generated with
the *Note `myisampack': myisampack. tool.  Compressed tables can be
uncompressed with *Note `myisamchk': myisamchk.

Compressed tables have the following characteristics:

   * Compressed tables take very little disk space. This minimizes disk
     usage, which is helpful when using slow disks (such as CD-ROMs).

   * Each row is compressed separately, so there is very little access
     overhead. The header for a row takes up one to three bytes
     depending on the biggest row in the table. Each column is
     compressed differently. There is usually a different Huffman tree
     for each column. Some of the compression types are:

        * Suffix space compression.

        * Prefix space compression.

        * Numbers with a value of zero are stored using one bit.

        * If values in an integer column have a small range, the column
          is stored using the smallest possible type. For example, a
          *Note `BIGINT': numeric-types. column (eight bytes) can be
          stored as a *Note `TINYINT': numeric-types. column (one byte)
          if all its values are in the range from `-128' to `127'.

        * If a column has only a small set of possible values, the data
          type is converted to *Note `ENUM': enum.

        * A column may use any combination of the preceding compression
          types.

   * Can be used for fixed-length or dynamic-length rows.

*Note*:

While a compressed table is read only, and you cannot therefore update
or add rows in the table, DDL (Data Definition Language) operations are
still valid. For example, you may still use `DROP' to drop the table,
and *Note `TRUNCATE': truncate. to empty the table.


File: manual.info,  Node: myisam-table-problems,  Prev: myisam-table-formats,  Up: myisam-storage-engine

13.5.4 `MyISAM' Table Problems
------------------------------

* Menu:

* corrupted-myisam-tables::      Corrupted `MyISAM' Tables
* myisam-table-close::           Problems from Tables Not Being Closed Properly

The file format that MySQL uses to store data has been extensively
tested, but there are always circumstances that may cause database
tables to become corrupted. The following discussion describes how this
can happen and how to handle it.


File: manual.info,  Node: corrupted-myisam-tables,  Next: myisam-table-close,  Prev: myisam-table-problems,  Up: myisam-table-problems

13.5.4.1 Corrupted `MyISAM' Tables
..................................

Even though the `MyISAM' table format is very reliable (all changes to
a table made by an SQL statement are written before the statement
returns), you can still get corrupted tables if any of the following
events occur:

   * The *Note `mysqld': mysqld. process is killed in the middle of a
     write.

   * An unexpected computer shutdown occurs (for example, the computer
     is turned off).

   * Hardware failures.

   * You are using an external program (such as *Note `myisamchk':
     myisamchk.) to modify a table that is being modified by the server
     at the same time.

   * A software bug in the MySQL or `MyISAM' code.

Typical symptoms of a corrupt table are:

   * You get the following error while selecting data from the table:

          Incorrect key file for table: '...'. Try to repair it

   * Queries don't find rows in the table or return incomplete results.

You can check the health of a `MyISAM' table using the *Note `CHECK
TABLE': check-table. statement, and repair a corrupted `MyISAM' table
with *Note `REPAIR TABLE': repair-table. When *Note `mysqld': mysqld.
is not running, you can also check or repair a table with the *Note
`myisamchk': myisamchk. command.  See *Note check-table::, *Note
repair-table::, and *Note myisamchk::.

If your tables become corrupted frequently, you should try to determine
why this is happening. The most important thing to know is whether the
table became corrupted as a result of a server crash. You can verify
this easily by looking for a recent `restarted mysqld' message in the
error log. If there is such a message, it is likely that table
corruption is a result of the server dying. Otherwise, corruption may
have occurred during normal operation. This is a bug. You should try to
create a reproducible test case that demonstrates the problem. See
*Note crashing::, and MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).

MySQL Enterprise

Find out about problems before they occur. Subscribe to the MySQL
Enterprise Monitor for expert advice about the state of your servers.
For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: myisam-table-close,  Prev: corrupted-myisam-tables,  Up: myisam-table-problems

13.5.4.2 Problems from Tables Not Being Closed Properly
.......................................................

Each `MyISAM' index file (`.MYI' file) has a counter in the header that
can be used to check whether a table has been closed properly. If you
get the following warning from *Note `CHECK TABLE': check-table. or
*Note `myisamchk': myisamchk, it means that this counter has gone out
of sync:

     clients are using or haven't closed the table properly

This warning doesn't necessarily mean that the table is corrupted, but
you should at least check the table.

The counter works as follows:

   * The first time a table is updated in MySQL, a counter in the
     header of the index files is incremented.

   * The counter is not changed during further updates.

   * When the last instance of a table is closed (because a *Note
     `FLUSH TABLES': flush. operation was performed or because there is
     no room in the table cache), the counter is decremented if the
     table has been updated at any point.

   * When you repair the table or check the table and it is found to be
     okay, the counter is reset to zero.

   * To avoid problems with interaction with other processes that might
     check the table, the counter is not decremented on close if it was
     zero.

In other words, the counter can become incorrect only under these
conditions:

   * A `MyISAM' table is copied without first issuing *Note `LOCK
     TABLES': lock-tables. and *Note `FLUSH TABLES': flush.

   * MySQL has crashed between an update and the final close.  (Note
     that the table may still be okay, because MySQL always issues
     writes for everything between each statement.)

   * A table was modified by *Note `myisamchk --recover': myisamchk. or
     *Note `myisamchk --update-state': myisamchk. at the same time that
     it was in use by *Note `mysqld': mysqld.

   * Multiple *Note `mysqld': mysqld. servers are using the table and
     one server performed a *Note `REPAIR TABLE': repair-table. or
     *Note `CHECK TABLE': check-table. on the table while it was in use
     by another server. In this setup, it is safe to use *Note `CHECK
     TABLE': check-table, although you might get the warning from other
     servers. However, *Note `REPAIR TABLE': repair-table. should be
     avoided because when one server replaces the data file with a new
     one, this is not known to the other servers.

     In general, it is a bad idea to share a data directory among
     multiple servers. See *Note multiple-servers::, for additional
     discussion.


File: manual.info,  Node: se-maria,  Next: innodb,  Prev: myisam-storage-engine,  Up: storage-engines

13.6 The `Maria' Storage Engine
===============================

* Menu:

* se-maria-configuration::       `Maria' Configuration
* se-maria-tableoptions::        `Maria' Table Options
* se-maria-log::                 `Maria' Transaction Log
* se-maria-recovery::            `Maria' Recovery
* se-maria-usagenotes::          `Maria' Usage Notes
* se-maria-concurrency::         `Maria' Statement Concurrency
* se-maria-designnotes::         `Maria' Design Notes
* se-maria-tools::               `Maria' Command-line Tools
* se-maria-openbugs::            `Maria' Open Bugs
* se-maria-faq::                 `Maria' FAQ

*Note*:

The `Maria' storage engine was introduced in MySQL 6.0.6.

`Maria' is a crash safe version of `MyISAM'. The `Maria' storage engine
supports all of the main functionality of the `MyISAM' engine, but
includes recovery support (in the event of a system crash), full
logging (including `CREATE', `DROP', `RENAME' and *Note `TRUNCATE':
truncate. operations), all `MyISAM' row formats and a new `Maria'
specific row format.

`Maria' has been designed as a replacement for the `MyISAM' storage
engine, supporting the speed and flexibility of the original `MyISAM'
implementation, in combination with MVCC transaction support. Within
the current release, a limited level of concurrency for *Note `INSERT':
insert./*Note `UPDATE': update.  and *Note `SELECT': select.
functionality is supported. For more information, see *Note
se-maria-concurrency::.

For more information on known bugs and limitations in `Maria', see
*Note se-maria-openbugs::

To create a `Maria' table you must specify the engine when using the
*Note `CREATE TABLE': create-table.  statement:

     mysql> CREATE TABLE maria_table (id int) ENGINE=Maria;

You can also use *Note `ALTER TABLE': alter-table. to convert an
existing table to the `Maria' engine:

     mysql> ALTER TABLE myisam_table ENGINE=Maria;

Data in `Maria' tables is stored in three files:

   * `table.frm' -- the standard MySQL FRM file containing the table
     definition.

   * `table.MAD' -- the `Maria' data file.

   * `table.MAI' -- the `Maria' index file.

In addition, `Maria' creates at least two additional files in your
standard `datadir' directory:

   * `maria_log.????????' -- the `Maria' log file. Each file is named
     numerically and sequentially, with new files automatically created
     when the log file limit has been reached. You can control the log
     file size using `maria_log_file_size' option, and control the
     deletion of logs using `maria_log_purge_type'.  The newly created
     files stay in place until deleted either automatically or manually.

   * `maria_log_control' -- a control file that holds information about
     the current state of the `Maria' engine.

     *Warning*:

     You should not delete the `maria_log_control' file from an active
     `Maria' installation as it records information about the current
     state of the `Maria' engine, including information about the log
     files and the default page block size used for the log and data
     files.

The basic functionality of `Maria' matches the functionality of
`MyISAM' with a number of differences. These are:

   * Two types of tables are supported. Non-crash safe tables
     (non-transactional) are written immediately to their corresponding
     data file. Transactional tables are crash safe and data is written
     into the `Maria' log. For more information on the log, see *Note
     se-maria-log::. Data which had already been written to the log is
     then applied to the data and index files as the statement
     completes.

   * `Maria' supports auto-recovery in the event of a crash. For more
     information, see *Note se-maria-recovery::.

   * `Maria' supports a single writer and multiple readers. The writer
     supports both *Note `INSERT': insert. and *Note `UPDATE': update.
     operations.  `MyISAM' supports only concurrent *Note `INSERT':
     insert. and *Note `SELECT': select. statements. For more
     information, see *Note se-maria-concurrency::.

   * `Maria' provides a new row format, `PAGE'. For more information,
     see *Note se-maria-tableoptions::. Existing `MyISAM' row formats
     are also supported on non-transactional tables.

   * `Maria' supports crash-safe operations over many statements by
     enclosing statements within *Note `LOCK TABLES': lock-tables. and
     *Note `UNLOCK TABLES': lock-tables. statements.


File: manual.info,  Node: se-maria-configuration,  Next: se-maria-tableoptions,  Prev: se-maria,  Up: se-maria

13.6.1 `Maria' Configuration
----------------------------

`Maria' supports a number of configuration options to control the
operation and performance of the storage engine. Many of the options
are similar to options that are already available within the `MyISAM'
configuration options. See *Note myisam-storage-engine::.

`Maria' command options:

*`mysqld' Maria Option/Variable Reference*

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
maria                         Yes                                                        Yes                                                                                                                                                                                                                                         
maria-block-size              Yes                                                        Yes                                                                                                                                                                                                                                         No
- _Variable_:                                                                                                                                       Yes                                                                                                                                                                              No
maria_block_size                                                                                                                                                                                                                                                                                                                     
maria-checkpoint-interval     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
maria-force-start-after-recovery-failuresYes                                                        Yes                                                                                                                                                                                                                                         
maria-log-dir-path            Yes                                                        Yes                                                                                                                                                                                                                                         
maria-log-file-size           Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_log_file_size                                                                                                                                                                                                                                                                                                                  
maria-log-purge-type          Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_log_purge_type                                                                                                                                                                                                                                                                                                                 
maria-max-sort-file-size      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
maria-page-checksum           Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_page_checksum                                                                                                                                                                                                                                                                                                                  
maria-pagecache-age-threshold Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_pagecache_age_threshold                                                                                                                                                                                                                                                                                                        
maria-pagecache-buffer-size   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
maria_pagecache_buffer_size                                                                                                                                                                                                                                                                                                          
maria-pagecache-division-limitYes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_pagecache_division_limit                                                                                                                                                                                                                                                                                                       
maria-recover                 Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: maria_recover                                                                                                                         Yes                                                                                                                   Global                                                     Yes
maria-repair-threads          Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
maria_repair_threads                                                                                                                                                                                                                                                                                                                 
maria-sort-buffer-size        Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
maria_sort_buffer_size                                                                                                                                                                                                                                                                                                               
maria-stats-method            Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
maria_stats_method                                                                                                                                                                                                                                                                                                                   
maria-sync-log-dir            Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
maria_sync_log_dir                                                                                                                                                                                                                                                                                                                   

   *  `maria' enables the `Maria' plugin. You can disable `Maria' by
     using `--skip-maria'.

     Default is for the `Maria' plugin to be enabled.

     *Note*:

     You cannot disable `Maria' if you have enabled `Maria' as the
     default engine for temporary tables using the `configure'
     `--with-maria-tmp-tables' option. If `--with-maria-tmp-tables' has
     been enabled it will be used for all temporary tables, including
     `INFORMATION_SCHEMA' tables.

   *  `maria-block-size'

     Sets the block size to be used for `Maria' index pages and data
     pages for the new `PAGE' row format. Once the page size has been
     set the first time `mysqld' has been run, you cannot change the
     page size without recreating all your `Maria' tables.

     *Note*:

     To change the block size of existing tables, you should use *Note
     `mysqldump': mysqldump. to save a copy of the table data, cleanly
     shutdown *Note `mysqld': mysqld, remove the `maria_log_control'
     file and associated logs, and reconfigure the block size before
     starting up *Note `mysqld': mysqld. again.

     The configuration setting of this value is recorded within the
     `maria_log_control' file the first time MySQL is started with the
     `Maria' engine enabled.

     The default size is 8192 (8KB).

   *  `maria-checkpoint-interval'

     Sets the interval between automatic checkpoints. Checkpoints in
     `Maria' synchronize the in-memory and on-disk data and then
     collate information about the current status of different
     transactions, before writing the information about the current
     status to the `Maria' log. The use of checkpoints improves the
     ability and speed of `Maria' when recovering from a crash, as
     recovery can continue from the last stable checkpoint in the log,
     instead of replaying the entire log.

     The default checkpoint interval is 30 seconds. You can disable
     checkpoints by setting the value to 0, but disabling checkpoints
     will increase the time taken to recover in the event of a failure.
     You should only set the value to 0 during testing.

     *Note*:

     This parameter was previously known as `maria_check_interval'.

   *  `maria-force-start-after-recovery-failures'

     Sets the maximum number of recovery operations to attempt before
     deleting the `Maria' log files and forcing *Note `mysqld': mysqld.
     to start. Recovery of the `Maria' tables using the log files may
     fail during startup, preventing *Note `mysqld': mysqld. from
     starting.

     Setting `maria-force-start-after-recovery-failures' to a non-zero
     value forces `Maria' to check the recovery count within the
     `Maria' log control file. This value is incremented each time a
     recovery is attempted. If the number of attempts matches the value
     of `maria-force-start-after-recovery-failures', then `Maria' will
     delete all the current log files before *Note `mysqld': mysqld.
     starts.

     Because forcing a start without recovery leaves tables in an
     inconsistent state, you should only set
     `maria-force-start-after-recovery-failures' in conjunction with
     the `maria-recovery' option, which forces checking and recovery of
     tables during startup without requiring the Maria log files.

     The default value is 0.

     *Note*:

     Setting `maria-force-start-after-recovery' may increase the
     downtime and recovery time, as the recovery will be attempted a
     number of times before startup is forced. However, without it,
     *Note `mysqld': mysqld. will fail to start up if there are broken
     tables.

   *  `maria_log_dir_path'

     Sets the path to the directory where the transactional log files
     and the log control file will be stored. You can set this to
     another device to improve performance.

     The default value is to use the same directory as the `datadir'
     option.

     *Note*:

     This option is only available through the configuration or
     command-line. You cannot change the location of the log files
     while *Note `mysqld': mysqld. is running.

   *  `maria_log_file_size'

     Sets the size of each of the `Maria' log files. When the log
     reaches this figure, a new log file (with a new sequential log
     file number) is created, and the `maria_log_control' file is
     updated.

     The default size is 1GB. The minimum log file size is 8MB and the
     maximum log file size is (4GB - 8192 bytes)

   *  `maria_log_purge_type'

     Specifies how the transactional log will be purged. Supported
     types are as follows:

        * `at_flush' -- the logs will be removed (deleted from disk)
          only when they have been marked 'free' (i.e. there are no
          pending transactions), and a *Note `FLUSH LOGS': flush.
          statement has been executed.

        * `immediate' -- the logs are deleted as soon as they no longer
          have pending transactions.

        * `external' -- the logs are not deleted automatically; it is
          assumed an external utility is responsible for actually
          deleting the logs. This can be used in combination with a
          backup solution to delete the logs only once a backup has
          been completed.

     Default is `immediate'.

   *  `maria_max_sort_file_size'

     Don't use the fast sort index method to create the index if the
     temporary file would get bigger than this size.

     Default is the maximum file size.

   *  `maria_page_checksum'

     Sets the default mode for page checksums. If a table has page
     checksums, then `Maria' will use the checksum to ensure that the
     page information is not corrupted. You can override page checksums
     on a table by table level by using the `PAGE_CHECKSUM' or
     `CHECKSUM' option during *Note `CREATE TABLE': create-table.

     Default is for `maria_page_checksum' to be enabled.

   *  `maria_pagecache_age_threshold'

     The number of hits that a hot block in the page cache has to be
     untouched until it is considered old enough to be downgraded to a
     warm block. Lower values cause demotion to happen more quickly.

     The default is 300.

   *  `maria_pagecache_buffer_size'

     Sets the size of the buffer used for data and index pages to
     `Maria' tables. You should increase this value to improve
     performance on data and index reads and writes, ideally to the
     maximum figure supported by your environment.

     The default value is 8MB.

   *  `maria_pagecache_division_limit'

     The minimum percentage of warm blocks in the page cache.

     The default value is 100.

   *  `maria_recover'

     Forces recovery of corrupted `Maria' tables without using the log
     files. Unlike the automatic recovery supported by `Maria' on
     transactional tables, `maria-recover' will work for all `Maria'
     tables.

   *  `maria_repair_threads'

     Number of threads to be used when repairing `Maria' tables when
     using *Note `REPAIR TABLE': repair-table. The default value of 1
     disables parallel repair.

   *  `maria_sort_buffer_size'

     Sets the size of the buffer that is allocated when sorting the
     index when doing a `REPAIR' or when creating indexes using *Note
     `CREATE INDEX': create-index. or *Note `ALTER TABLE': alter-table.
     Increasing this option will improve the speed of the index
     creation process.

     The default value is 8MB.

   *  `maria_stats_method'

     Specifies how index statistics collection treats `NULL' values.
     Valid choices are `nulls_unequal', `nulls_equal', `nulls_ignored'.

     The default setting is `nulls_unequal'.

   *  `maria_sync_log_dir'

     Controls the synchronization of the directory after a log file has
     been extended or a new log file has been created.  Supported
     values are `never', `newfile' (only when a new log file is
     created), and `always'.

     The default setting is `newfile'.


File: manual.info,  Node: se-maria-tableoptions,  Next: se-maria-log,  Prev: se-maria-configuration,  Up: se-maria

13.6.2 `Maria' Table Options
----------------------------

There are a number of options available when you create a new `Maria'
table:

   * `PAGE_CHECKSUM'

     The `PAGE_CHECKSUM' table option specifies whether a page checksum
     for the table should be enabled. The checksum can either be
     switched on (value 1) or off (value 0).  The default value of this
     option is implied by the `maria_page_checksum' variable.

     Because the default value of the `PAGE_CHECKSUM' option is
     configurable, the checksum setting is always included in the
     output of *Note `SHOW CREATE TABLE': show-create-table. if it was
     enabled when the table was created.

   * `TRANSACTIONAL'

     `Maria' tables can be either transactional or non-transactional.
     For `Maria' versions less than 2.0, `TRANSACTIONAL' means
     crash-safe.  Full transaction support will only be available with
     `Maria' 2.0 and later.

     Changes to transactional tables are recorded in the `Maria' log
     and use slightly more space per row than non-transactional tables.
     By default all tables are transactional i.e. `TRANSACTIONAL=1' is
     implied within the *Note `CREATE TABLE': create-table.
     definition. This means that the transactional status of the table
     is not written in the output of the *Note `SHOW CREATE TABLE':
     show-create-table. output:

          mysql> create table maria_trans (id int, title char(20)) engine=Maria;
          Query OK, 0 rows affected (0.05 sec)

          mysql> SHOW CREATE TABLE maria_trans;
          +-------------+---------------------------------------+
          | Table       | Create Table                          |
          +-------------+---------------------------------------+
          | maria_trans | CREATE TABLE `maria_trans` (
             `id` int(11) DEFAULT NULL,
             `title` char(20) DEFAULT NULL
          ) ENGINE=MARIA DEFAULT CHARSET=latin1 PAGE_CHECKSUM=1 |
          +-------------+---------------------------------------+
          1 row in set (0.00 sec)

     If you create a non-crash safe (non-transactional) table then the
     option is shown

          mysql> CREATE TABLE maria_nontrans (id INT, title CHAR(20)) ENGINE=Maria TRANSACTIONAL=0;
          Query OK, 0 rows affected (0.02 sec)

          mysql> SHOW CREATE TABLE maria_nontrans;
          +----------------+----------------------------------------------------+
          | Table          | Create Table                                       |
          +----------------+----------------------------------------------------+
          | maria_nontrans | CREATE TABLE `maria_nontrans` (
             `id` int(11) DEFAULT NULL,
             `title` char(20) DEFAULT NULL
          ) ENGINE=MARIA DEFAULT CHARSET=latin1 PAGE_CHECKSUM=1 TRANSACTIONAL=0 |
          +----------------+----------------------------------------------------+
          1 row in set (0.00 sec)

     Currently, transactional tables cannot handle `SPATIAL' or
     `FULLTEXT' indexes. You must use a non-transactional table if you
     want to use these index key types. If you try to create a table
     with these options, then an error will occur during *Note `CREATE
     TABLE': create-table.

   * `TABLE_CHECKSUM', `CHECKSUM'

     Forces MySQL to maintain a live checksum for all rows in the
     table. This maintains a rolling checksum (i.e. one that changes
     when the table data changes), and can be used to identify
     corrupted tables. This is identical to the `CHECKSUM' on `MyISAM'
     tables.

     The *Note `CHECKSUM TABLE': checksum-table. statement, which
     returns the checksum for a given table, ignores record's columns
     which have a `NULL' value. This is different behavior from
     standard MySQL 5.1.

In addition, `Maria' supports the following row formats:

   * *Note `FIXED': numeric-types. -- identical to the *Note `FIXED':
     numeric-types. row format used by `MyISAM'. Must be used with
     non-transactional tables (i.e. where `TRANSACTIONAL=0').

   * `DYNAMIC' -- identical to the `DYNAMIC' row format used by
     `MyISAM'. Must be used with non-transactional tables (i.e. where
     `TRANSACTIONAL=0').

   * `PAGE' -- new `Maria' row format where data and index information
     is written into pages. The `PAGE' option can be used with
     `TRANSACTIONAL=0' or `TRANSACTIONAL=1'. The `PAGE' format uses a
     different caching mechanism than `MyISAM'. For more information,
     see *Note se-maria-configuration::.

     `Maria' data pages in `PAGE' format have an overhead of 10
     bytes/page and 5 bytes/row.  Transaction and multiple concurrent
     writer support will use an additional overhead of 7 bytes for new
     rows, 14 bytes for deleted rows and 0 bytes for old compacted rows.


File: manual.info,  Node: se-maria-log,  Next: se-maria-recovery,  Prev: se-maria-tableoptions,  Up: se-maria

13.6.3 `Maria' Transaction Log
------------------------------

The transaction log within `Maria' keeps a record of all changes,
including DDL, to tables created using the `TRANSACTIONAL' table
option. Events from all tables and all databases are written into a
single log file sequence. The `Maria' log consists of one log control
file (`maria_log_control') and one or more maria log files (named
`maria_log.????????', where `????????' is an eight-digit number with a
maximum value of 16777215). The log control file and log file are
created automatically when *Note `mysqld': mysqld. is started.

The log contains a copy of all the data and the log can be used to
replay and verify the contents of the data files in the event of a
crash. Checkpoints saves information about the current transactions,
opened files and other statusw information that will be required if the
log needs to be used during recover.  Checkpoints are written every 30
seconds by default, although you can increase or decrease this value.

For tables using the transactional format, statements that change data
(DML statements) are recorded in the log file and these changes are
also ultimately written to the data and index files.  There is no fixed
point when the application of data written to the log is also written
to the data and index files. The process happens continuously in the
background during normal execution.  Although the data and index files
and the transaction log may be out of sync, all of the information is
always available. In the event of a crash, the recovery process will
replay and apply the contents of the log to bring the data and log
files back into synchronization.

Additional log files are created when the log file reaches the
configured maximum size (as controlled by `maria_log_file_size'). The
default value is 1GB.  This option can be controlled as a global
variable and set with the configuration file or on the command line.

You can determine the list of current log files using the statement
*Note `SHOW ENGINE MARIA LOGS': show-engine.:

     mysql> SHOW ENGINE MARIA LOGS;
     +--------+-------------------------------------------------------------+----------+
     | Type   | Name                                                        | Status   |
     +--------+-------------------------------------------------------------+----------+
     | maria  | Size    191627264 ; /usr/local/mysql/var/maria_log.00000009 | unknown  |
     +--------+-------------------------------------------------------------+----------+
     1 row in set (0.00 sec)

The `Status' shows the current status of the log file:

   * `unknown' -- no checkpoint has taken place, so the current status
     of the log file is unknown.

   * `in-use' -- information is still being written to or read from the
     log, or outstanding statements are still active that have
     information active within the log file.

   * `free' -- the log file and any statements related to it have been
     completed and safely committed to disk, and the log file is no
     longer active.

Any other message indicates an error in reading the log file
information.

New log files are created automatically as the size of the current log
file reaches the configured size. For example, shown below are the log
files after a statement that inserted a large volume of data was
executed after the `maria_log_file_size' variable has been reduced to
8MB (the minimum supported value):

     mysql> SHOW ENGINE MARIA LOGS;
     +--------+-------------------------------------------------------------+---------+
     | Type   | Name                                                        | Status  |
     +--------+-------------------------------------------------------------+---------+
     | maria  | Size    191627264 ; /usr/local/mysql/var/maria_log.00000009 | in use  |
     | maria  | Size      8388608 ; /usr/local/mysql/var/maria_log.00000010 | in use  |
     | maria  | Size      8388608 ; /usr/local/mysql/var/maria_log.00000011 | in use  |
     | maria  | Size      8388608 ; /usr/local/mysql/var/maria_log.00000012 | in use  |
     | maria  | Size      8388608 ; /usr/local/mysql/var/maria_log.00000013 | in use  |
     | maria  | Size      8388608 ; /usr/local/mysql/var/maria_log.00000014 | in use  |
     | maria  | Size      8388608 ; /usr/local/mysql/var/maria_log.00000015 | in use  |
     | maria  | Size       139264 ; /usr/local/mysql/var/maria_log.00000016 | in use  |
     +--------+-------------------------------------------------------------+---------+
     8 rows in set (0.00 sec)

Log files that no longer have transactions or outstanding events where
the data has been safely committed on disk are marked 'free':

     mysql> SHOW ENGINE MARIA LOGS;
     +--------+-------------------------------------------------------------+---------+
     | Type   | Name                                                        | Status  |
     +--------+-------------------------------------------------------------+---------+
     | maria  | Size      8388608 ; /usr/local/mysql/var/maria_log.00000002 | free    |
     | maria  | Size      2170880 ; /usr/local/mysql/var/maria_log.00000003 | in use  |
     +--------+-------------------------------------------------------------+---------+
     2 rows in set (0.00 sec)

Log files are deleted according to the setting of the
`maria_log_purge_type' dynamic variable. Three options are supported,
`immediate', `external' and `at_flush'.

In `immediate' mode, the log files are deleted as soon as they no
longer have outstanding transactions or events.  This reduces the disk
space used by these logs, but means that the logs cannot be transferred
to another machine for replaying. This setting should not affect
recovery functionality, as only logs where there is no outstanding data
to be committed are deleted.

In `at_flush' mode, the log files are only deleted when you execute the
*Note `FLUSH LOGS': flush.  statement. Issuing this statement will
delete the logs that have the 'free' status, and therefore will not
affect logs with outstanding transactions or events.

     mysql> SHOW ENGINE MARIA LOGS;
     +--------+-------------------------------------------------------------+---------+
     | Type   | Name                                                        | Status  |
     +--------+-------------------------------------------------------------+---------+
     | maria  | Size      8388608 ; /usr/local/mysql/var/maria_log.00000002 | free    |
     | maria  | Size      8388608 ; /usr/local/mysql/var/maria_log.00000003 | free    |
     | maria  | Size      8388608 ; /usr/local/mysql/var/maria_log.00000004 | free    |
     | maria  | Size      4325376 ; /usr/local/mysql/var/maria_log.00000005 | in use  |
     +--------+-------------------------------------------------------------+---------+
     4 rows in set (0.00 sec)

     mysql> FLUSH LOGS;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SHOW ENGINE MARIA LOGS;
     +--------+-------------------------------------------------------------+---------+
     | Type   | Name                                                        | Status  |
     +--------+-------------------------------------------------------------+---------+
     | maria  | Size      4325376 ; /usr/local/mysql/var/maria_log.00000005 | in use  |
     +--------+-------------------------------------------------------------+---------+
     1 row in set (0.00 sec)

When `maria_log_purge_type' is set to `external', log files are not
deleted by MySQL at all. Instead, it is assumed that an external
process is responsible for deleting log files. Care should be taken
with this setting as you should only delete log files that `Maria' is
no longer using.

Transaction log file events can be viewed using the `maria_read_log'
command, which also provides the ability to replay log file contents
and apply them to tables without running *Note `mysqld': mysqld. For
more information, see *Note se-maria-tools::.


File: manual.info,  Node: se-maria-recovery,  Next: se-maria-usagenotes,  Prev: se-maria-log,  Up: se-maria

13.6.4 `Maria' Recovery
-----------------------

Any change (creation, insertion, deletion, update, etc.) in a `Maria'
table using the transactional format is automatically written to the
`Maria' log. Changes to non-transactional tables are not written to the
log.

The basic operation of the recovery process is in two main stages:

   * Replay the contents of the log and update the data and index
     information.

   * Roll back any statements that had not completed, or where the
     transactions have not been committed.

More specifically, in the event of a crash or other failure of *Note
`mysqld': mysqld, the following takes place during the next invocation
of *Note `mysqld': mysqld.:

   * Last checkpoint will be read from the log and the log will be
     replayed from the point calculated on the data contained within
     the checkpoint record. This point may be before the actual
     checkpoint.

   * If a checkpoint is not available (for example, if the log file was
     newly created and no checkpoint was written when the crash
     occurred), then all events are replayed from the start of the log
     file.

   * For each active connection, events are replayed until the last
     statement that completed before the crash occured, unless the
     statement was executed after a *Note `LOCK TABLES': lock-tables.
     statement, in which case recovery takes place to the last
     statement executed before the *Note `LOCK TABLES': lock-tables.
     statement was issued.

     Because multiple connections can be active at the same time,
     recovery takes place for each connection individually.

   * During recovery, if a statement fails due to a unique key
     violation, then the entire statement is not rolled back. Only the
     data that would have triggered the unique key violation is rolled
     back. For example, if you had executed the following statements
     into a table with a unique key:

          INSERT VALUES (1);
          INSERT VALUES (2),(1)

     The second statement would generate a unique key violation, but
     during recovery the statement would not be rolled back.  The table
     would still contain two rows containing the first two values.

You can see a sample of the recovery process after a crash below:

     080111 16:42:05 mysqld_safe Number of processes running now: 0
     080111 16:42:05 mysqld_safe mysqld restarted
     080111 16:42:05 [Note] mysqld: Maria engine: starting recovery
     recovered pages: 0% 99% 100% (0.9 seconds); transactions to roll back: 1 0 (3.8 seconds); tables to flush: 1 0 (0.5 seconds);
     080111 16:42:10 [Note] mysqld: Maria engine: recovery done
     080111 16:42:10 [Note] Event Scheduler: Loaded 0 events
     080111 16:42:10 [Note] /usr/local/mysql/libexec/mysqld: ready for connections.

Recovery is automatic, but the length of time for recovery increases in
line with the number of incomplete statements and tables known to be
out of synchronization with the log. The recovery process is
single-threaded and cannot be configured.


File: manual.info,  Node: se-maria-usagenotes,  Next: se-maria-concurrency,  Prev: se-maria-recovery,  Up: se-maria

13.6.5 `Maria' Usage Notes
--------------------------

When using `Maria' you should be aware of the following information and
notes:

   * When using `Maria' tables and transactions, statements operate
     using the `REPEATABLE READ' isolation level, except when running
     *Note `REPAIR TABLE': repair-table, *Note `OPTIMIZE TABLE':
     optimize-table, or *Note `ALTER TABLE': alter-table, when all rows
     are exposed to all statements regardless of the isolation level.

   * When `Maria' is enabled, and if MySQL has been built using the
     `configure' option `--with-maria-tmp-tables', then all internal
     on-disk temporary tables, including `INFORMATION_SCHEMA', will be
     created using the `Maria' storage engine, in place of `MyISAM'.

   * You should not delete the `maria_log_control', or the associated
     log files, except within the following circumstances:

        * When changing the size of the pages used in `Maria' data and
          index files.

        * If the `maria_log_control' gets corrupted.

        * If you want to rebuild all your `Maria' tables.

     Outside of these situations, deleting the `maria_log_control' may
     cause loss of data.

     If you delete `maria_log_control' and then want to use any
     existing `Maria' tables, you should shutdown *Note `mysqld':
     mysqld. You can then either manually run `maria_check --zerofill'
     to check the structure and format of each `Maria' table, or you
     can wait until the first access of the table, when the check will
     be performed automatically. On very large tables, the check should
     be performed manually to ensure that there is no delay during
     usage.

   * If you want to copy `Maria' tables from one system to another, use
     the following sequence:

       1. Check the status of the `Maria' logs and ensure that the
          events written to the log have been applied to the tables.

       2. Shutdown the `mysqld' server.

       3. Copy the `Maria' table files. Do not copy the log files or the
          `maria_log_control'.

       4. On the new system, run `maria_check --zerofill' on each table
          that you have copied to the new system.


File: manual.info,  Node: se-maria-concurrency,  Next: se-maria-designnotes,  Prev: se-maria-usagenotes,  Up: se-maria

13.6.6 `Maria' Statement Concurrency
------------------------------------

The concurrency of statement execution on tables is handled differently
in `Maria' depending on whether you are using non-transactional or
transactional tables.

For non-transactional tables, the rules are identical to MyISAM:

   * *Note `SELECT': select.

     All issued *Note `SELECT': select.'s are running concurrently.
     While a *Note `SELECT': select. is running, all writers (*Note
     `INSERT': insert, *Note `DELETE': delete, *Note `UPDATE': update.)
     are blocked from using any of the used tables (i.e., they wait for
     the table to be free before continuing) . The only exception is
     that one `INSERT CONCURRENT' can be run on each table that doesn't
     have any deleted rows.

   * *Note `UPDATE': update.

     Only one *Note `UPDATE': update. statement can run at the same
     time on each table. While the *Note `UPDATE': update. is running
     all other threads are blocked from using this table.

   * *Note `DELETE': delete.

     Only one *Note `DELETE': delete. statement can run at the same
     time on each table. While the *Note `DELETE': delete. is running
     all other threads are blocked from using this table.

   * *Note `INSERT': insert.

     If `INSERT CONCURRENT' is used, and there are no deleted rows in
     the table, only one `INSERT CONCURRENT' statement can run at the
     same time on each table. While the `INSERT CONCURRENT' is running
     all other writer threads are blocked for using this table. Any
     number of *Note `SELECT': select.  statements can use this table.

     If normal *Note `INSERT': insert. is used or if there are deleted
     rows in the table, only one INSERT statement can run at the same
     time on the table. While the *Note `INSERT': insert. is running all
     *Note `SELECT': select, *Note `INSERT': insert, *Note `DELETE':
     delete. and *Note `UPDATE': update. are blocked from using this
     table.

   * `CREATE' or `DROP'

     `CREATE''s on different tables can be run concurrently. On the
     same table, first creator wins.  `DROP' waits until all statements
     using the tables are completed, after which the table is dropped.

When using transactional tables, `Maria' supports a single writer and
multiple readers. The single writer supports both *Note `INSERT':
insert. and *Note `UPDATE': update. operations.

   * *Note `SELECT': select.

     All issued *Note `SELECT': select.'s are running concurrently.
     While a *Note `SELECT': select. is running, all writers (*Note
     `INSERT': insert, *Note `DELETE': delete, *Note `UPDATE': update.)
     are blocked from using any of the used tables (ie, they wait for
     the table to be free before continuing).

   * *Note `UPDATE': update.

     As part of the single writer, only one *Note `UPDATE': update.
     statement can run at the same time on each table. While the *Note
     `UPDATE': update. is running all other threads using *Note
     `UPDATE': update. or *Note `INSERT': insert. are blocked from using
     this table.

   * *Note `INSERT': insert.

     As part of the single writer, only one *Note `INSERT': insert.
     statement can run at the same time on the table. While the *Note
     `INSERT': insert. is running all other threads using *Note
     `UPDATE': update. or *Note `INSERT': insert. are blocked from using
     this table.

   * *Note `DELETE': delete.

     Only one *Note `DELETE': delete. statement can run at the same
     time on each table. While the *Note `DELETE': delete. is running
     all other threads are blocked from using this table.

   * `CREATE' or `DROP'

     `CREATE' operations on different tables can be run concurrently.
     On the same table, first creator wins.  `DROP' waits until all
     statements using the tables are completed, after which the table
     is dropped.

Multiple concurrent *Note `INSERT': insert.  statements are supported,
with the following notes:

   * To use multiple writers you should lock tables using the statement:

          LOCK TABLES TABLE_NAME WRITE CONCURRENT

   * During multiple write operations, all *Note `SELECT': select.
     statements operate in `REPEATABLE READ' mode.

   * All *Note `INSERT': insert. statements are considered atomic, and
     will use concurrent insert locks to ensure consistency.

   * Concurrent inserts are not supported on:

        * Non-transactional tables.

        * Transactional tables that have GIS (spatial) or `FULLTEXT'
          indexes.

        * Empty tables.


File: manual.info,  Node: se-maria-designnotes,  Next: se-maria-tools,  Prev: se-maria-concurrency,  Up: se-maria

13.6.7 `Maria' Design Notes
---------------------------

`Maria' supports all aspects of `MyISAM', except as noted below. This
includes external and internal check/repair/compressing of rows,
different row formats, different index compress formats, maria_check
etc.  After a normal shutdown one can copy `Maria' files between
servers.

*Advantages of `Maria' (Compared to `MyISAM') *

   * Data and indexes are crash safe. On crash, things will rollback to
     state of the start of statement or last *Note `LOCK TABLES':
     lock-tables. commands.

   * `Maria' can replay everything from the log.  Including
     `CREATE'/`DROP'/`RENAME'/*Note `TRUNCATE': truncate.  tables.

   * *Note `LOAD INDEX': load-index. can skip index blocks for not
     wanted indexes

   * Supports all `MyISAM' row formats and the new transactional format
     where data is stored in pages.

   * When using transactional format (default) row data can be cached.

   * `Maria' has unit tests of most parts

   * Supports both crash safe (soon to be transactional) and not
     transactional tables. (Not transactional tables are not logged and
     rows uses less space.) `CREATE TABLE foo (...)  TRANSACTIONAL=0|1'

   * Transactional is the only crashsafe/transactional row format.

   * Block format should give a notable speed improvement on systems
     with bad data caching (for example Windows).

*Differences between `Maria' and `MyISAM' *

   * `Maria' uses big (1GB by default) log files.

   * `Maria' has a log control file (`maria_log_control') and log files
     ( `maria_log.????????'). The log files can be automatically purged
     when not needed or purged on demand (after backup).

   * `Maria' uses by default 8K pages for indexes (`MyISAM' 1K). `Maria'
     should be faster on static size indexes but slower on variable
     length keys (until we add a directory to index pages).

*Disadvantages of `Maria' (compared to `MyISAM'), that will be fixed in
forthcoming releases.*

   * `Maria' 1.0 has one writer or many readers.  (`MyISAM' can have
     one inserter and many readers when using concurrent inserts.)

   * Storage of very small rows (< 25 bytes) is not efficient for
     `PAGE' format.

   * In `Maria' `PAGE' format there is an overhead of 10 bytes/page and
     5 bytes/row.  Transaction and multiple concurrent writer support
     will use an additional overhead of 7 bytes for new rows, 14 bytes
     for deleted rows and 0 bytes for old compacted rows.

   * `Maria' doesn't support *Note `INSERT DELAYED': insert-delayed.

   * The `maria_page_buffer_size' system variable that controls the
     `Maria' page cache size is not dynamically settable like the
     corresponding `MyISAM' variable, `key_buffer_size'.

*Differences that are not likely to be fixed*

   * No external locking (`MyISAM' has external locking, but it is not
     much used).

   * `Maria' has one page size for both index and data (defined when
     `Maria' is used first time). `MyISAM' supports different page sizes
     per index.

   * Index requires one extra byte per index page.

   * `Maria' doesn't support RAID (disabled in `MyISAM' too).

   * Minimum data file size for `PAGE' format is 16K (with 8K pages).


File: manual.info,  Node: se-maria-tools,  Next: se-maria-openbugs,  Prev: se-maria-designnotes,  Up: se-maria

13.6.8 `Maria' Command-line Tools
---------------------------------

`Maria' supports a number of command-line tools which operate in a
similar fashion to the corresponding `MyISAM' tools. These are:

   * `maria_chk' -- checks `Maria' tables for corruption. Similar to the
     *Note `myisamchk': myisamchk. command; see *Note myisamchk::.

   * `maria_ftdump' -- dumps information about fulltext indexes in
     `Maria' tables.  Similar to the *Note `myisam_ftdump':
     myisam-ftdump. command; see *Note myisam-ftdump::.

   * `maria_pack' -- packs a `Maria' table to save space. Similar to the
     *Note `myisampack': myisampack. command; see *Note myisampack::.

   * `maria_read_log' -- displays the contents of a `Maria' log file or
     applies the contents to existing tables. This tool is a utility
     for the log files but is not used or required for recovery of data
     from the log file.

   * `maria_dump_log' -- used for interpreting log content for people
     who understand maria transaction log internals.


File: manual.info,  Node: se-maria-openbugs,  Next: se-maria-faq,  Prev: se-maria-tools,  Up: se-maria

13.6.9 `Maria' Open Bugs
------------------------

This section contains all known fatal bugs in the `Maria' storage
engine for the last source or binary release. Minor bugs, extensions
and feature requests and bugs, found since this release can be found in
the MySQL bugs databases at: http://bugs.mysql.com/
(http://bugs.mysql.com/).  When reporting a bug, make sure you select
the `Maria' category for the bug.

*Note*:

You can find additional information in the `KNOWN_BUGS.txt' file within
the `Maria' repository.

There shouldn't normally be any bugs that affect normal operations in
any `Maria' release. Still, there are always exceptions and edge cases
and that is what this section is for.

If you have found a bug that is not listed here, please add it to
http://bugs.mysql.com/ (http://bugs.mysql.com/) so that we can either
fix it for next release or in the worst case add it here for others to
know! When reporting a bug, make sure you select the `Maria' category
for the bug.

*Known bugs that are planned to be fixed before next minor release*

   * If the log files are damaged or inconsistent, `Maria' may fail to
     start. We should fix that if this happens and mysqld is restarted
     (thanks to mysqld_safe, instance manager or other script) it should
     disregard the old logs, start anyway and automatically repair any
     tables that were found to be crashed on open.

     Temporary fix is to remove ` maria_log.????????' files from the
     data directory, restart *Note `mysqld': mysqld. and run *Note
     `CHECK TABLE': check-table./*Note `REPAIR TABLE': repair-table. or
     *Note `mysqlcheck': mysqlcheck. on your `Maria' tables.

     *Warning*:

     Do not remove the `maria_log_control' file, as this contains the
     page size information required for reading `Maria' log and data
     files.

*Known bugs that are planned to be fixed before Beta *

   * If we get a write failure on disk for the log, we should stop all
     usage of transactional tables and mark all transactional tables
     that are changed as crashed.

   * *Missing features that are planned to be fixed before Beta*

   * We will add a maria-recover option to automatically repair any
     crashed tables on open. (This is needed for non-transactional
     tables and also in edge cases for transactional tables when the
     table crashed because of a bug in MySQL or `Maria' code)

*Features planned for future releases*

You can find details on additional features and functionality planned
for `Maria', see MySQL Forge Worklog (http://forge.mysql.com/worklog/).


File: manual.info,  Node: se-maria-faq,  Prev: se-maria-openbugs,  Up: se-maria

13.6.10 `Maria' FAQ
-------------------

The following entries cover some of the frequently asked questions
about `Maria'.

*Questions*
   * 13.6.10.1: Is `DELAY_KEY_WRITE' honored on Maria tables?

   * 13.6.10.2: Is there compression of text/blob columns or entire
     pages in Maria?

*Questions and Answers* *13.6.10.1: ** Is `DELAY_KEY_WRITE' honored on
Maria tables?  *

If you are using non-transactional `Maria' tables (`CREATE TABLE...
ENGINE=MARIA TRANSACTIONAL=0'), which are similar to `MyISAM', then
`DELAY_KEY_WRITE' works as you expect. If you are using transactional
`Maria' tables (the default), then `DELAY_KEY_WRITE' is always enabled.
In `MyISAM' and non-transactional `Maria' tables (which have no
logging), by default all the table's key pages are flushed to the OS at
the end of each statement, to guarantee some durability.
`DELAY_KEY_WRITE' removes this flush, giving less durability. In
transactional `Maria' tables, key pages are flushed by a background
job, regularly, not necessarily at the end of each statement, and
durability is guaranteed thanks to logging.

*13.6.10.2: ** Is there compression of text/blob columns or entire
pages in Maria?  *

No, there is no compression of `TEXT'/`BLOB' in `Maria'. You can use the
`compress()'/`uncompress()' functions on the SQL level to store/retrieve
`BLOB'/`TEXT' in compressed format.


File: manual.info,  Node: innodb,  Next: se-falcon,  Prev: se-maria,  Up: storage-engines

13.7 The `InnoDB' Storage Engine
================================

* Menu:

* innodb-contact-information::   `InnoDB' Contact Information
* innodb-configuration::         `InnoDB' Configuration
* innodb-parameters::            `InnoDB' Startup Options and System Variables
* using-innodb-tables::          Creating and Using `InnoDB' Tables
* adding-and-removing::          Adding, Removing, or Resizing `InnoDB' Data and Log Files
* innodb-backup::                Backing Up and Recovering an `InnoDB' Database
* moving::                       Moving an `InnoDB' Database to Another Machine
* innodb-transaction-model::     The `InnoDB' Transaction Model and Locking
* innodb-multi-versioning::      `InnoDB' Multi-Versioning
* innodb-table-and-index::       `InnoDB' Table and Index Structures
* file-space-management::        `InnoDB' Disk I/O and File Space Management
* innodb-error-handling::        `InnoDB' Error Handling
* innodb-tuning-troubleshooting::  `InnoDB' Performance Tuning and Troubleshooting
* innodb-restrictions::          Restrictions on `InnoDB' Tables

`InnoDB' is a transaction-safe (ACID compliant) storage engine for
MySQL that has commit, rollback, and crash-recovery capabilities to
protect user data.  `InnoDB' row-level locking (without escalation to
coarser granularity locks) and Oracle-style consistent non-locking
reads increase multi-user concurrency and performance.  `InnoDB' stores
user data in clustered indexes to reduce I/O for common queries based
on primary keys. To maintain data integrity, `InnoDB' also supports
`FOREIGN KEY' referential-integrity constraints.  You can freely mix
`InnoDB' tables with tables from other MySQL storage engines, even
within the same statement.

To determine whether your server supports `InnoDB' use the *Note `SHOW
ENGINES': show-engines. statement. See *Note show-engines::.

*InnoDB Features*

*Storage limits* 64TB     *Transactions*   Yes      *Locking         Row
                                                    granularity*     
*MVCC*           Yes      *Geospatial      Yes      *Geospatial      No
                          datatype                  indexing         
                          support*                  support*         
*B-tree indexes* Yes      *Hash indexes*   No       *Full-text       No
                                                    search indexes*  
*Clustered       Yes      *Data caches*    Yes      *Index caches*   Yes
indexes*                                                             
*Compressed      Yes      *Encrypted data  Yes      *Cluster         No
data*            CompressedImplemented in            database         
                 InnoDB   the server (via           support*         
                 tables   encryption                                 
                 are      functions),                                
                 supportedrather than in                             
                 only by  the storage                                
                 InnoDB   engine.*                                   
                 Plugin.                                             
*Replication     Yes      *Foreign key     Yes      *Backup /        Yes
support                   support*                  point-in-time    
Implemented in                                      recovery         
the server,                                         Implemented in   
rather than in                                      the server,      
the storage                                         rather than in   
engine*                                             the storage      
                                                    engine*          
*Query cache     Yes      *Update          Yes                       
support*                  statistics for                             
                          data dictionary*                           

`InnoDB' has been designed for maximum performance when processing
large data volumes. Its CPU efficiency is probably not matched by any
other disk-based relational database engine.

The `InnoDB' storage engine maintains its own buffer pool for caching
data and indexes in main memory.  `InnoDB' stores its tables and
indexes in a tablespace, which may consist of several files (or raw disk
partitions). This is different from, for example, `MyISAM' tables where
each table is stored using separate files. `InnoDB' tables can be very
large even on operating systems where file size is limited to 2GB.

The Windows Essentials installer makes `InnoDB' the MySQL default
storage engine on Windows, if the server being installed supports
`InnoDB'.

`InnoDB' is used in production at numerous large database sites
requiring high performance. The famous Internet news site Slashdot.org
runs on `InnoDB'. Mytrix, Inc.  stores more than 1TB of data in
`InnoDB', and another site handles an average load of 800
inserts/updates per second in `InnoDB'.

`InnoDB' is published under the same GNU GPL License Version 2 (of June
1991) as MySQL. For more information on MySQL licensing, see
`http://www.mysql.com/company/legal/licensing/'.

*Additional resources*

   * A forum dedicated to the `InnoDB' storage engine is available at
     `http://forums.mysql.com/list.php?22'.

   * Innobase Oy also hosts several forums, available at
     `http://forums.innodb.com'.

   * `InnoDB Hot Backup' enables you to back up a running MySQL
     database, including `InnoDB' and `MyISAM' tables, with minimal
     disruption to operations while producing a consistent snapshot of
     the database. When `InnoDB Hot Backup' is copying `InnoDB' tables,
     reads and writes to both `InnoDB' and `MyISAM' tables can
     continue. During the copying of `MyISAM' tables, reads (but not
     writes) to those tables are permitted. In addition, `InnoDB Hot
     Backup' supports creating compressed backup files, and performing
     backups of subsets of `InnoDB' tables. In conjunction with MySQL's
     binary log, users can perform point-in-time recovery.  `InnoDB Hot
     Backup' is commercially licensed by Innobase Oy. For a more
     complete description of `InnoDB Hot Backup', see
     `http://www.innodb.com/hot-backup/features/' or download the
     documentation from
     `http://www.innodb.com/doc/hot_backup/manual.html'.  You can order
     trial, term, and perpetual licenses from Innobase at
     `http://www.innodb.com/hot-backup/order/'.


File: manual.info,  Node: innodb-contact-information,  Next: innodb-configuration,  Prev: innodb,  Up: innodb

13.7.1 `InnoDB' Contact Information
-----------------------------------

Contact information for Innobase Oy, producer of the `InnoDB' engine:

Web site: `http://www.innodb.com/'

Email: `innodb_sales_ww at oracle.com' or use this contact form:
`http://www.innodb.com/contact-form'

Phone:

     +358-9-6969 3250 (office, Heikki Tuuri)
     +358-40-5617367 (mobile, Heikki Tuuri)
     +358-40-5939732 (mobile, Satu Sire'n)

Address:

     Innobase Oy Inc.
     World Trade Center Helsinki
     Aleksanterinkatu 17
     P.O.Box 800
     00101 Helsinki
     Finland


File: manual.info,  Node: innodb-configuration,  Next: innodb-parameters,  Prev: innodb-contact-information,  Up: innodb

13.7.2 `InnoDB' Configuration
-----------------------------

* Menu:

* multiple-tablespaces::         Using Per-Table Tablespaces
* innodb-raw-devices::           Using Raw Devices for the Shared Tablespace
* innodb-init::                  Creating the `InnoDB' Tablespace
* error-creating-innodb::        Dealing with `InnoDB' Initialization Problems

If you do not want to use `InnoDB' tables, start the server with the
`--skip-innodb' option to disable the `InnoDB' startup engine.

*Caution*:

`InnoDB' is a transaction-safe (ACID compliant) storage engine for
MySQL that has commit, rollback, and crash-recovery capabilities to
protect user data.  *However, it cannot do so* if the underlying
operating system or hardware does not work as advertised. Many
operating systems or disk subsystems may delay or reorder write
operations to improve performance. On some operating systems, the very
`fsync()' system call that should wait until all unwritten data for a
file has been flushed might actually return before the data has been
flushed to stable storage. Because of this, an operating system crash
or a power outage may destroy recently committed data, or in the worst
case, even corrupt the database because of write operations having been
reordered. If data integrity is important to you, you should perform
some `pull-the-plug' tests before using anything in production. On Mac
OS X 10.3 and up, `InnoDB' uses a special `fcntl()' file flush method.
Under Linux, it is advisable to *disable the write-back cache*.

On ATA/SATA disk drives, a command such `hdparm -W0 /dev/hda' may work
to disable the write-back cache.  *Beware that some drives or disk
controllers may be unable to disable the write-back cache.*

Two important disk-based resources managed by the `InnoDB' storage
engine are its tablespace data files and its log files. If you specify
no `InnoDB' configuration options, MySQL creates an auto-extending 10MB
data file named `ibdata1' and two 5MB log files named `ib_logfile0' and
`ib_logfile1' in the MySQL data directory. To get good performance, you
should explicitly provide `InnoDB' parameters as discussed in the
following examples. Naturally, you should edit the settings to suit your
hardware and requirements.

*Caution*:

It is not a good idea to configure `InnoDB' to use data files or log
files on NFS volumes. Otherwise, the files might be locked by other
processes and become unavailable for use by MySQL.

MySQL Enterprise

For advice on settings suitable to your specific circumstances,
subscribe to the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The examples shown here are representative. See *Note
innodb-parameters:: for additional information about `InnoDB'-related
configuration parameters.

To set up the `InnoDB' tablespace files, use the
`innodb_data_file_path' option in the `[mysqld]' section of the
`my.cnf' option file. On Windows, you can use `my.ini' instead. The
value of `innodb_data_file_path' should be a list of one or more data
file specifications. If you name more than one data file, separate them
by semicolon (``;'') characters:

     innodb_data_file_path=DATAFILE_SPEC1[;DATAFILE_SPEC2]...

For example, the following setting explicitly creates a tablespace
having the same characteristics as the default:

     [mysqld]
     innodb_data_file_path=ibdata1:10M:autoextend

This setting configures a single 10MB data file named `ibdata1' that is
auto-extending. No location for the file is given, so by default,
`InnoDB' creates it in the MySQL data directory.

Sizes are specified using `K', `M', or `G' suffix letters to indicate
units of KB, MB, or GB.

A tablespace containing a fixed-size 50MB data file named `ibdata1' and
a 50MB auto-extending file named `ibdata2' in the data directory can be
configured like this:

     [mysqld]
     innodb_data_file_path=ibdata1:50M;ibdata2:50M:autoextend

The full syntax for a data file specification includes the file name,
its size, and several optional attributes:

     FILE_NAME:FILE_SIZE[:autoextend[:max:MAX_FILE_SIZE]]

The `autoextend' and `max' attributes can be used only for the last
data file in the `innodb_data_file_path' line.

If you specify the `autoextend' option for the last data file, `InnoDB'
extends the data file if it runs out of free space in the tablespace.
The increment is 8MB at a time by default. To modify the increment,
change the `innodb_autoextend_increment' system variable.

If the disk becomes full, you might want to add another data file on
another disk. For tablespace reconfiguration instructions, see *Note
adding-and-removing::.

`InnoDB' is not aware of the file system maximum file size, so be
cautious on file systems where the maximum file size is a small value
such as 2GB. To specify a maximum size for an auto-extending data file,
use the `max' attribute following the `autoextend' attribute.  The
following configuration allows `ibdata1' to grow up to a limit of 500MB:

     [mysqld]
     innodb_data_file_path=ibdata1:10M:autoextend:max:500M

`InnoDB' creates tablespace files in the MySQL data directory by
default. To specify a location explicitly, use the
`innodb_data_home_dir' option.  For example, to use two files named
`ibdata1' and `ibdata2' but create them in the `/ibdata' directory,
configure `InnoDB' like this:

     [mysqld]
     innodb_data_home_dir = /ibdata
     innodb_data_file_path=ibdata1:50M;ibdata2:50M:autoextend

*Note*:

`InnoDB' does not create directories, so make sure that the `/ibdata'
directory exists before you start the server. This is also true of any
log file directories that you configure. Use the Unix or DOS `mkdir'
command to create any necessary directories.

Make sure that the MySQL server has the proper access rights to create
files in the data directory. More generally, the server must have
access rights in any directory where it needs to create data files or
log files.

`InnoDB' forms the directory path for each data file by textually
concatenating the value of `innodb_data_home_dir' to the data file
name, adding a path name separator (slash or backslash) between values
if necessary. If the `innodb_data_home_dir' option is not mentioned in
`my.cnf' at all, the default value is the `dot' directory `./', which
means the MySQL data directory. (The MySQL server changes its current
working directory to its data directory when it begins executing.)

If you specify `innodb_data_home_dir' as an empty string, you can
specify absolute paths for the data files listed in the
`innodb_data_file_path' value. The following example is equivalent to
the preceding one:

     [mysqld]
     innodb_data_home_dir =
     innodb_data_file_path=/ibdata/ibdata1:50M;/ibdata/ibdata2:50M:autoextend

*A simple `my.cnf' example.* Suppose that you have a computer with 512MB
RAM and one hard disk. The following example shows possible
configuration parameters in `my.cnf' or `my.ini' for `InnoDB',
including the `autoextend' attribute. The example suits most users,
both on Unix and Windows, who do not want to distribute `InnoDB' data
files and log files onto several disks. It creates an auto-extending
data file `ibdata1' and two `InnoDB' log files `ib_logfile0' and
`ib_logfile1' in the MySQL data directory.

     [mysqld]
     # You can write your other MySQL server options here
     # ...
     # Data files must be able to hold your data and indexes.
     # Make sure that you have enough free disk space.
     innodb_data_file_path = ibdata1:10M:autoextend
     #
     # Set buffer pool size to 50-80% of your computer's memory
     innodb_buffer_pool_size=256M
     innodb_additional_mem_pool_size=20M
     #
     # Set the log file size to about 25% of the buffer pool size
     innodb_log_file_size=64M
     innodb_log_buffer_size=8M
     #
     innodb_flush_log_at_trx_commit=1

Note that data files must be less than 2GB in some file systems.  The
combined size of the log files must be less than 4GB. The combined size
of data files must be at least 10MB.

When you create an `InnoDB' tablespace for the first time, it is best
that you start the MySQL server from the command prompt. `InnoDB' then
prints the information about the database creation to the screen, so
you can see what is happening. For example, on Windows, if *Note
`mysqld': mysqld. is located in `C:\Program Files\MySQL\MySQL Server
6.0\bin', you can start it like this:

     C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqld" --console

If you do not send server output to the screen, check the server's
error log to see what `InnoDB' prints during the startup process.

For an example of what the information displayed by `InnoDB' should
look like, see *Note innodb-init::.

You can place `InnoDB' options in the `[mysqld]' group of any option
file that your server reads when it starts. The locations for option
files are described in *Note option-files::.

If you installed MySQL on Windows using the installation and
configuration wizards, the option file will be the `my.ini' file
located in your MySQL installation directory. See The Location of the
my.ini File
(http://dev.mysql.com/doc/refman/4.1/en/windows-config-wizard.html#mysql-config-wizard-file-location).

If your PC uses a boot loader where the `C:' drive is not the boot
drive, your only option is to use the `my.ini' file in your Windows
directory (typically `C:\WINDOWS'). You can use the `SET' command at
the command prompt in a console window to print the value of `WINDIR':

     C:\> SET WINDIR
     windir=C:\WINDOWS

To make sure that *Note `mysqld': mysqld. reads options only from a
specific file, use the `--defaults-file' option as the first option on
the command line when starting the server:

     mysqld --defaults-file=YOUR_PATH_TO_MY_CNF

*An advanced `my.cnf' example.* Suppose that you have a Linux computer
with 2GB RAM and three 60GB hard disks at directory paths `/', `/dr2'
and `/dr3'. The following example shows possible configuration
parameters in `my.cnf' for `InnoDB'.

     [mysqld]
     # You can write your other MySQL server options here
     # ...
     innodb_data_home_dir =
     #
     # Data files must be able to hold your data and indexes
     innodb_data_file_path = /db/ibdata1:2000M;/dr2/db/ibdata2:2000M:autoextend
     #
     # Set buffer pool size to 50-80% of your computer's memory,
     # but make sure on Linux x86 total memory usage is < 2GB
     innodb_buffer_pool_size=1G
     innodb_additional_mem_pool_size=20M
     innodb_log_group_home_dir = /dr3/iblogs
     #
     # Set the log file size to about 25% of the buffer pool size
     innodb_log_file_size=250M
     innodb_log_buffer_size=8M
     #
     innodb_flush_log_at_trx_commit=1
     innodb_lock_wait_timeout=50
     #
     # Uncomment the next line if you want to use it
     #innodb_thread_concurrency=5

In some cases, database performance improves if the data is not all
placed on the same physical disk. Putting log files on a different disk
from data is very often beneficial for performance.  The example
illustrates how to do this. It places the two data files on different
disks and places the log files on the third disk. `InnoDB' fills the
tablespace beginning with the first data file. You can also use raw
disk partitions (raw devices) as `InnoDB' data files, which may speed
up I/O. See *Note innodb-raw-devices::.

*Warning*:

On 32-bit GNU/Linux x86, you must be careful not to set memory usage
too high. `glibc' may allow the process heap to grow over thread
stacks, which crashes your server. It is a risk if the value of the
following expression is close to or exceeds 2GB:

     innodb_buffer_pool_size
     + key_buffer_size
     + max_connections*(sort_buffer_size+read_buffer_size+binlog_cache_size)
     + max_connections*2MB

Each thread uses a stack (often 2MB, but only 256KB in MySQL AB
binaries) and in the worst case also uses `sort_buffer_size +
read_buffer_size' additional memory.

*Tuning other *Note `mysqld': mysqld.  server parameters.* The
following values are typical and suit most users:

     [mysqld]
     skip-external-locking
     max_connections=200
     read_buffer_size=1M
     sort_buffer_size=1M
     #
     # Set key_buffer to 5 - 50% of your RAM depending on how much
     # you use MyISAM tables, but keep key_buffer_size + InnoDB
     # buffer pool size < 80% of your RAM
     key_buffer_size=VALUE

On Linux, if the kernel is enabled for large page support, `InnoDB' can
use large pages to allocate memory for its buffer pool and additional
memory pool. See *Note large-page-support::.


File: manual.info,  Node: multiple-tablespaces,  Next: innodb-raw-devices,  Prev: innodb-configuration,  Up: innodb-configuration

13.7.2.1 Using Per-Table Tablespaces
....................................

You can store each `InnoDB' table and its indexes in its own file. This
feature is called `multiple tablespaces' because in effect each table
has its own tablespace.

Using multiple tablespaces can be beneficial to users who want to move
specific tables to separate physical disks or who wish to restore
backups of single tables quickly without interrupting the use of other
`InnoDB' tables.

To enable multiple tablespaces, start the server with the
`--innodb_file_per_table' option.  For example, add a line to the
`[mysqld]' section of `my.cnf':

     [mysqld]
     innodb_file_per_table

With multiple tablespaces enabled, `InnoDB' stores each newly created
table into its own `TBL_NAME.ibd' file in the database directory where
the table belongs. This is similar to what the `MyISAM' storage engine
does, but `MyISAM' divides the table into a `TBL_NAME.MYD' data file
and an `TBL_NAME.MYI' index file. For `InnoDB', the data and the
indexes are stored together in the `.ibd' file. The `TBL_NAME.frm' file
is still created as usual.

You cannot freely move `.ibd' files between database directories as you
can with `MyISAM' table files. This is because the table definition
that is stored in the `InnoDB' shared tablespace includes the database
name, and because `InnoDB' must preserve the consistency of transaction
IDs and log sequence numbers.

If you remove the `innodb_file_per_table' line from `my.cnf' and
restart the server, `InnoDB' creates tables inside the shared
tablespace files again.

The `--innodb_file_per_table' option affects only table creation, not
access to existing tables. If you start the server with this option,
new tables are created using `.ibd' files, but you can still access
tables that exist in the shared tablespace. If you start the server
without this option, new tables are created in the shared tablespace,
but you can still access any tables that were created using multiple
tablespaces.

*Note*:

`InnoDB' always needs the shared tablespace because it puts its
internal data dictionary and undo logs there. The `.ibd' files are not
sufficient for `InnoDB' to operate.

To move an `.ibd' file and the associated table from one database to
another, use a *Note `RENAME TABLE': rename-table. statement:

     RENAME TABLE DB1.TBL_NAME TO DB2.TBL_NAME;

If you have a `clean' backup of an `.ibd' file, you can restore it to
the MySQL installation from which it originated as follows:

  1. Issue this *Note `ALTER TABLE': alter-table.  statement to delete
     the current `.ibd' file:

          ALTER TABLE TBL_NAME DISCARD TABLESPACE;

  2. Copy the backup `.ibd' file to the proper database directory.

  3. Issue this *Note `ALTER TABLE': alter-table.  statement to tell
     `InnoDB' to use the new `.ibd' file for the table:

          ALTER TABLE TBL_NAME IMPORT TABLESPACE;

In this context, a `clean' `.ibd' file backup is one for which the
following requirements are satisfied:

   * There are no uncommitted modifications by transactions in the
     `.ibd' file.

   * There are no unmerged insert buffer entries in the `.ibd' file.

   * Purge has removed all delete-marked index records from the `.ibd'
     file.

   * *Note `mysqld': mysqld. has flushed all modified pages of the
     `.ibd' file from the buffer pool to the file.

You can make a clean backup `.ibd' file using the following method:

  1. Stop all activity from the *Note `mysqld': mysqld. server and
     commit all transactions.

  2. Wait until *Note `SHOW ENGINE INNODB STATUS': show-engine. shows
     that there are no active transactions in the database, and the
     main thread status of `InnoDB' is `Waiting for server activity'.
     Then you can make a copy of the `.ibd' file.

Another method for making a clean copy of an `.ibd' file is to use the
commercial `InnoDB Hot Backup' tool:

  1. Use `InnoDB Hot Backup' to back up the `InnoDB' installation.

  2. Start a second *Note `mysqld': mysqld. server on the backup and
     let it clean up the `.ibd' files in the backup.


File: manual.info,  Node: innodb-raw-devices,  Next: innodb-init,  Prev: multiple-tablespaces,  Up: innodb-configuration

13.7.2.2 Using Raw Devices for the Shared Tablespace
....................................................

You can use raw disk partitions as data files in the shared tablespace.
By using a raw disk, you can perform non-buffered I/O on Windows and on
some Unix systems without file system overhead. This may improve
performance, but you are advised to perform tests with and without raw
partitions to verify whether this is actually so on your system.

When you create a new data file, you must put the keyword `newraw'
immediately after the data file size in `innodb_data_file_path'. The
partition must be at least as large as the size that you specify. Note
that 1MB in `InnoDB' is 1024 x 1024 bytes, whereas 1MB in disk
specifications usually means 1,000,000 bytes.

     [mysqld]
     innodb_data_home_dir=
     innodb_data_file_path=/dev/hdd1:3Gnewraw;/dev/hdd2:2Gnewraw

The next time you start the server, `InnoDB' notices the `newraw'
keyword and initializes the new partition. However, do not create or
change any `InnoDB' tables yet. Otherwise, when you next restart the
server, `InnoDB' reinitializes the partition and your changes are lost.
(As a safety measure `InnoDB' prevents users from modifying data when
any partition with `newraw' is specified.)

After `InnoDB' has initialized the new partition, stop the server,
change `newraw' in the data file specification to `raw':

     [mysqld]
     innodb_data_home_dir=
     innodb_data_file_path=/dev/hdd1:5Graw;/dev/hdd2:2Graw

Then restart the server and `InnoDB' allows changes to be made.

On Windows, you can allocate a disk partition as a data file like this:

     [mysqld]
     innodb_data_home_dir=
     innodb_data_file_path=//./D::10Gnewraw

The `//./' corresponds to the Windows syntax of `\\.\' for accessing
physical drives.

When you use a raw disk partition, be sure that it has permissions that
allow read and write access by the account used for running the MySQL
server. For example, if you run the server as the `mysql' user, the
partition must allow read and write access to `mysql'. If you run the
server with the `--memlock' option, the server must be run as `root', so
the partition must allow access to `root'.


File: manual.info,  Node: innodb-init,  Next: error-creating-innodb,  Prev: innodb-raw-devices,  Up: innodb-configuration

13.7.2.3 Creating the `InnoDB' Tablespace
.........................................

Suppose that you have installed MySQL and have edited your option file
so that it contains the necessary `InnoDB' configuration parameters.
Before starting MySQL, you should verify that the directories you have
specified for `InnoDB' data files and log files exist and that the
MySQL server has access rights to those directories. `InnoDB' does not
create directories, only files. Check also that you have enough disk
space for the data and log files.

It is best to run the MySQL server *Note `mysqld': mysqld.  from the
command prompt when you first start the server with `InnoDB' enabled,
not from *Note `mysqld_safe': mysqld-safe. or as a Windows service.
When you run from a command prompt you see what *Note `mysqld': mysqld.
prints and what is happening. On Unix, just invoke *Note `mysqld':
mysqld. On Windows, start *Note `mysqld': mysqld. with the `--console'
option to direct the output to the console window.

When you start the MySQL server after initially configuring `InnoDB' in
your option file, `InnoDB' creates your data files and log files, and
prints something like this:

     InnoDB: The first specified datafile /home/heikki/data/ibdata1
     did not exist:
     InnoDB: a new database to be created!
     InnoDB: Setting file /home/heikki/data/ibdata1 size to 134217728
     InnoDB: Database physically writes the file full: wait...
     InnoDB: datafile /home/heikki/data/ibdata2 did not exist:
     new to be created
     InnoDB: Setting file /home/heikki/data/ibdata2 size to 262144000
     InnoDB: Database physically writes the file full: wait...
     InnoDB: Log file /home/heikki/data/logs/ib_logfile0 did not exist:
     new to be created
     InnoDB: Setting log file /home/heikki/data/logs/ib_logfile0 size
     to 5242880
     InnoDB: Log file /home/heikki/data/logs/ib_logfile1 did not exist:
     new to be created
     InnoDB: Setting log file /home/heikki/data/logs/ib_logfile1 size
     to 5242880
     InnoDB: Doublewrite buffer not found: creating new
     InnoDB: Doublewrite buffer created
     InnoDB: Creating foreign key constraint system tables
     InnoDB: Foreign key constraint system tables created
     InnoDB: Started
     mysqld: ready for connections

At this point `InnoDB' has initialized its tablespace and log files.
You can connect to the MySQL server with the usual MySQL client
programs like *Note `mysql': mysql. When you shut down the MySQL server
with *Note `mysqladmin shutdown': mysqladmin, the output is like this:

     010321 18:33:34  mysqld: Normal shutdown
     010321 18:33:34  mysqld: Shutdown Complete
     InnoDB: Starting shutdown...
     InnoDB: Shutdown completed

You can look at the data file and log directories and you see the files
created there. When MySQL is started again, the data files and log
files have been created already, so the output is much briefer:

     InnoDB: Started
     mysqld: ready for connections

If you add the `innodb_file_per_table' option to `my.cnf', `InnoDB'
stores each table in its own `.ibd' file in the same MySQL database
directory where the `.frm' file is created. See *Note
multiple-tablespaces::.


File: manual.info,  Node: error-creating-innodb,  Prev: innodb-init,  Up: innodb-configuration

13.7.2.4 Dealing with `InnoDB' Initialization Problems
......................................................

If `InnoDB' prints an operating system error during a file operation,
usually the problem has one of the following causes:

   * You did not create the `InnoDB' data file directory or the
     `InnoDB' log directory.

   * *Note `mysqld': mysqld. does not have access rights to create
     files in those directories.

   * *Note `mysqld': mysqld. cannot read the proper `my.cnf' or `my.ini'
     option file, and consequently does not see the options that you
     specified.

   * The disk is full or a disk quota is exceeded.

   * You have created a subdirectory whose name is equal to a data file
     that you specified, so the name cannot be used as a file name.

   * There is a syntax error in the `innodb_data_home_dir' or
     `innodb_data_file_path' value.

If something goes wrong when `InnoDB' attempts to initialize its
tablespace or its log files, you should delete all files created by
`InnoDB'. This means all `ibdata' files and all `ib_logfile' files. In
case you have already created some `InnoDB' tables, delete the
corresponding `.frm' files for these tables (and any `.ibd' files if
you are using multiple tablespaces) from the MySQL database directories
as well. Then you can try the `InnoDB' database creation again. It is
best to start the MySQL server from a command prompt so that you see
what is happening.


File: manual.info,  Node: innodb-parameters,  Next: using-innodb-tables,  Prev: innodb-configuration,  Up: innodb

13.7.3 `InnoDB' Startup Options and System Variables
----------------------------------------------------

This section describes the `InnoDB'-related command options and system
variables. System variables that are true or false can be enabled at
server startup by naming them, or disabled by using a `--skip' prefix.
For example, to enable or disable `InnoDB' checksums, you can use
`--innodb_checksums' or `--skip-innodb_checksums' on the command line,
or `innodb_checksums' or `skip-innodb_checksums' in an option file.
System variables that take a numeric value can be specified as
`--VAR_NAME=VALUE' on the command line or as `VAR_NAME=VALUE' in option
files. For more information on specifying options and system variables,
see *Note program-options::. Many of the system variables can be
changed at runtime (see *Note dynamic-system-variables::).

MySQL Enterprise

The MySQL Enterprise Monitor provides expert advice on InnoDB start-up
options and related system variables. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*`mysqld' InnoDB Option/Variable Reference*

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
Com_show_innodb_status                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_ndb_status                                                                                                                                                                                            Yes                                                        Both                                                       No
foreign_key_checks                                                                                                                                  Yes                                                                                                                   Session                                                    Yes
have_innodb                                                                                                                                         Yes                                                                                                                   Global                                                     No
innodb                        Yes                                                        Yes                                                                                                                                                                                                                                         
innodb_adaptive_hash_index    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_additional_mem_pool_sizeYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_autoextend_increment   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_autoinc_lock_mode      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_buffer_pool_pages_data                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_dirty                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_flushed                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_free                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_latched                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_misc                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_total                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_ahead_rnd                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_ahead_seq                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_requests                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_reads                                                                                                                                                                                       Yes                                                        Global                                                     No
innodb_buffer_pool_size       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_buffer_pool_wait_free                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_buffer_pool_write_requests                                                                                                                                                                                 Yes                                                        Global                                                     No
innodb_checksums              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_commit_concurrency     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_concurrency_tickets    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_data_file_path         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_data_fsyncs                                                                                                                                                                                             Yes                                                        Global                                                     No
innodb_data_home_dir          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_data_pending_fsyncs                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_data_pending_reads                                                                                                                                                                                      Yes                                                        Global                                                     No
Innodb_data_pending_writes                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_data_read                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_data_reads                                                                                                                                                                                              Yes                                                        Global                                                     No
Innodb_data_writes                                                                                                                                                                                             Yes                                                        Global                                                     No
Innodb_data_written                                                                                                                                                                                            Yes                                                        Global                                                     No
Innodb_dblwr_pages_written                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_dblwr_writes                                                                                                                                                                                            Yes                                                        Global                                                     No
innodb_doublewrite            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_fast_shutdown          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_file_io_threads        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_file_per_table         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_flush_log_at_trx_commitYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_flush_method           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_force_recovery         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_lock_wait_timeout      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_locks_unsafe_for_binlogYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_buffer_size        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_file_size          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_files_in_group     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_group_home_dir     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_log_waits                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_log_write_requests                                                                                                                                                                                      Yes                                                        Global                                                     No
Innodb_log_writes                                                                                                                                                                                              Yes                                                        Global                                                     No
innodb_max_dirty_pages_pct    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_max_purge_lag          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_mirrored_log_groups    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_open_files             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_os_log_fsyncs                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_os_log_pending_fsyncs                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_os_log_pending_writes                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_os_log_written                                                                                                                                                                                          Yes                                                        Global                                                     No
Innodb_page_size                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_pages_created                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_pages_read                                                                                                                                                                                              Yes                                                        Global                                                     No
Innodb_pages_written                                                                                                                                                                                           Yes                                                        Global                                                     No
innodb_rollback_on_timeout    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_row_lock_current_waits                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_row_lock_time                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_row_lock_time_avg                                                                                                                                                                                       Yes                                                        Global                                                     No
Innodb_row_lock_time_max                                                                                                                                                                                       Yes                                                        Global                                                     No
Innodb_row_lock_waits                                                                                                                                                                                          Yes                                                        Global                                                     No
Innodb_rows_deleted                                                                                                                                                                                            Yes                                                        Global                                                     No
Innodb_rows_inserted                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_rows_read                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_rows_updated                                                                                                                                                                                            Yes                                                        Global                                                     No
innodb_stats_on_metadata      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_status_file            Yes                                                        Yes                                                                                                                                                                                                                                         
innodb_support_xa             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
innodb_sync_spin_loops        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_table_locks            Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
innodb_thread_concurrency     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_thread_sleep_delay     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
skip-innodb                   Yes                                                        Yes                                                                                                                                                                                                                                         
skip-innodb-checksums         Yes                                                        Yes                                                                                                                                                                                                                                         
timed_mutexes                 Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
unique_checks                                                                                                                                       Yes                                                                                                                   Session                                                    Yes

`InnoDB' command options:

   *  `--innodb'

     Enables the `InnoDB' storage engine, if the server was compiled
     with `InnoDB' support.  Use `--skip-innodb' to disable `InnoDB'.

   *  `--innodb_status_file'

     Controls whether `InnoDB' creates a file named
     `innodb_status.<PID>' in the MySQL data directory. If enabled,
     `InnoDB' periodically writes the output of *Note `SHOW ENGINE
     INNODB STATUS': show-engine. to this file.

     By default, the file is not created. To create it, start *Note
     `mysqld': mysqld. with the `--innodb_status_file=1' option.  The
     file is deleted during normal shutdown.

`InnoDB' system variables:

   *  `innodb_adaptive_hash_index'

     Whether InnoDB adaptive hash indexes are enabled or disabled (see
     *Note innodb-adaptive-hash::). This variable is enabled by
     default. Use `--skip-innodb_adaptive_hash_index' at server startup
     to disable it. This variable was added in MySQL 6.0.5.

   *  `innodb_additional_mem_pool_size'

     The size in bytes of a memory pool `InnoDB' uses to store data
     dictionary information and other internal data structures. The
     more tables you have in your application, the more memory you need
     to allocate here. If `InnoDB' runs out of memory in this pool, it
     starts to allocate memory from the operating system and writes
     warning messages to the MySQL error log. The default value is 1MB.

   *  `innodb_autoextend_increment'

     The increment size (in MB) for extending the size of an
     auto-extending tablespace file when it becomes full. The default
     value is 8.

   *  `innodb_autoinc_lock_mode'

     The locking mode to use for generating auto-increment values.  The
     allowable values are 0, 1, or 2, for `traditional', `consecutive',
     or `interleaved' lock mode, respectively.  *Note
     innodb-auto-increment-handling::, describes the characteristics of
     these modes.

     This variable has a default of 1 (`consecutive' lock mode).

   *  `innodb_buffer_pool_size'

     The size in bytes of the memory buffer `InnoDB' uses to cache data
     and indexes of its tables. The default value is 8MB. The larger
     you set this value, the less disk I/O is needed to access data in
     tables.  On a dedicated database server, you may set this to up to
     80% of the machine physical memory size. However, do not set it
     too large because competition for physical memory might cause
     paging in the operating system.

   *  `innodb_checksums'

     `InnoDB' can use checksum validation on all pages read from the
     disk to ensure extra fault tolerance against broken hardware or
     data files. This validation is enabled by default. However, under
     some rare circumstances (such as when running benchmarks) this
     extra safety feature is unneeded and can be disabled with
     `--skip-innodb-checksums'.

   *  `innodb_commit_concurrency'

     The number of threads that can commit at the same time. A value of
     0 (the default) allows any number of transactions to commit
     simultaneously.

   *  `innodb_concurrency_tickets'

     The number of threads that can enter `InnoDB' concurrently is
     determined by the `innodb_thread_concurrency' variable. A thread
     is placed in a queue when it tries to enter `InnoDB' if the number
     of threads has already reached the concurrency limit. When a
     thread is allowed to enter `InnoDB', it is given a number of `free
     tickets' equal to the value of `innodb_concurrency_tickets', and
     the thread can enter and leave `InnoDB' freely until it has used
     up its tickets. After that point, the thread again becomes subject
     to the concurrency check (and possible queuing) the next time it
     tries to enter `InnoDB'. The default value is 500.

   *  `innodb_data_file_path'

     The paths to individual data files and their sizes. The full
     directory path to each data file is formed by concatenating
     `innodb_data_home_dir' to each path specified here. The file sizes
     are specified in KB, MB, or GB (1024MB) by appending `K', `M', or
     `G' to the size value. The sum of the sizes of the files must be
     at least 10MB. If you do not specify `innodb_data_file_path', the
     default behavior is to create a single 10MB auto-extending data
     file named `ibdata1'. The size limit of individual files is
     determined by your operating system.  You can set the file size to
     more than 4GB on those operating systems that support big files.
     You can also use raw disk partitions as data files. For detailed
     information on configuring `InnoDB' tablespace files, see *Note
     innodb-configuration::.

   *  `innodb_data_home_dir'

     The common part of the directory path for all `InnoDB' data files.
     The default value is the MySQL data directory. If you specify the
     value as an empty string, you can use absolute file paths in
     `innodb_data_file_path'.

   *  `innodb_doublewrite'

     If this variable is enabled (the default), `InnoDB' stores all
     data twice, first to the doublewrite buffer, and then to the
     actual data files. This variable can be turned off with
     `--skip-innodb_doublewrite' for benchmarks or cases when top
     performance is needed rather than concern for data integrity or
     possible failures.

   *  `innodb_fast_shutdown'

     The `InnoDB' shutdown mode. By default, the value is 1, which
     causes a `fast' shutdown (the normal type of shutdown). If the
     value is 0, `InnoDB' does a full purge and an insert buffer merge
     before a shutdown. These operations can take minutes, or even
     hours in extreme cases. If the value is 1, `InnoDB' skips these
     operations at shutdown.  If the value is 2, `InnoDB' will just
     flush its logs and then shut down cold, as if MySQL had crashed; no
     committed transaction will be lost, but crash recovery will be
     done at the next startup. A value of 2 cannot be used on NetWare.

   *  `innodb_file_io_threads'

     The number of file I/O threads in `InnoDB'.  Normally, this should
     be left at the default value of 4, but disk I/O on Windows may
     benefit from a larger number. On Unix, increasing the number has
     no effect; `InnoDB' always uses the default value.

   *  `innodb_file_per_table'

     If `innodb_file_per_table' is disabled (the default), `InnoDB'
     creates tables in the shared tablespace. If
     `innodb_file_per_table' is enabled, `InnoDB' creates each new table
     using its own `.ibd' file for storing data and indexes, rather
     than in the shared tablespace. See *Note multiple-tablespaces::.

   *  `innodb_flush_log_at_trx_commit'

     If the value of `innodb_flush_log_at_trx_commit' is 0, the log
     buffer is written out to the log file once per second and the
     flush to disk operation is performed on the log file, but nothing
     is done at a transaction commit. When the value is 1 (the
     default), the log buffer is written out to the log file at each
     transaction commit and the flush to disk operation is performed on
     the log file. When the value is 2, the log buffer is written out
     to the file at each commit, but the flush to disk operation is not
     performed on it. However, the flushing on the log file takes place
     once per second also when the value is 2. Note that the
     once-per-second flushing is not 100% guaranteed to happen every
     second, due to process scheduling issues.

     The default value of 1 is the value required for ACID compliance.
     You can achieve better performance by setting the value different
     from 1, but then you can lose at most one second worth of
     transactions in a crash. With a value of 0, any *Note `mysqld':
     mysqld. process crash can erase the last second of transactions.
     With a value of 2, then only an operating system crash or a power
     outage can erase the last second of transactions. However,
     `InnoDB''s crash recovery is not affected and thus crash recovery
     does work regardless of the value.

     For the greatest possible durability and consistency in a
     replication setup using `InnoDB' with transactions, use
     `innodb_flush_log_at_trx_commit = 1' and `sync_binlog = 1' in your
     master server `my.cnf' file.

     *Caution*:

     Many operating systems and some disk hardware fool the
     flush-to-disk operation. They may tell *Note `mysqld': mysqld.
     that the flush has taken place, even though it has not. Then the
     durability of transactions is not guaranteed even with the setting
     1, and in the worst case a power outage can even corrupt the
     `InnoDB' database. Using a battery-backed disk cache in the SCSI
     disk controller or in the disk itself speeds up file flushes, and
     makes the operation safer. You can also try using the Unix command
     `hdparm' to disable the caching of disk writes in hardware caches,
     or use some other command specific to the hardware vendor.

   *  `innodb_flush_method'

     By default, `InnoDB' uses `fsync()' to flush both the data and log
     files. If `innodb_flush_method' option is set to `O_DSYNC',
     `InnoDB' uses `O_SYNC' to open and flush the log files, and
     `fsync()' to flush the data files. If `O_DIRECT' is specified
     (available on some GNU/Linux versions, FreeBSD, and Solaris),
     `InnoDB' uses `O_DIRECT' (or `directio()' on Solaris) to open the
     data files, and uses `fsync()' to flush both the data and log
     files. Note that `InnoDB' uses `fsync()' instead of `fdatasync()',
     and it does not use `O_DSYNC' by default because there have been
     problems with it on many varieties of Unix. This variable is
     relevant only for Unix. On Windows, the flush method is always
     `async_unbuffered' and cannot be changed.

     Different values of this variable can have a marked effect on
     `InnoDB' performance. For example, on some systems where `InnoDB'
     data and log files are located on a SAN, it has been found that
     setting `innodb_flush_method' to `O_DIRECT' can degrade
     performance of simple *Note `SELECT': select. statements by a
     factor of three.

   *  `innodb_force_recovery'

     The crash recovery mode. Possible values are from 0 to 6. The
     meanings of these values are described in *Note forcing-recovery::.

     *Warning*:

     This variable should be set greater than 0 only in an emergency
     situation when you want to dump your tables from a corrupt
     database! As a safety measure, `InnoDB' prevents any changes to
     its data when this variable is greater than 0.

   *  `innodb_lock_wait_timeout'

     The timeout in seconds an `InnoDB' transaction may wait for a row
     lock before giving up. The default value is 50 seconds. A
     transaction that tries to access a row that is locked by another
     `InnoDB' transaction will hang for at most this many seconds
     before issuing the following error:

          ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction

     When a lock wait timeout occurs, the current statement is not
     executed. The current transaction is _not_ rolled back. (To have
     the entire transaction roll back, start the server with the
     `--innodb_rollback_on_timeout' option. See also *Note
     innodb-error-handling::.)

     `innodb_lock_wait_timeout' applies to `InnoDB' row locks only. A
     MySQL table lock does not happen inside `InnoDB' and this timeout
     does not apply to waits for table locks.

     `InnoDB' does detect transaction deadlocks in its own lock table
     immediately and rolls back one transaction.  The lock wait timeout
     value does not apply to such a wait.

   *  `innodb_locks_unsafe_for_binlog'

     This variable affects how `InnoDB' uses gap locking for searches
     and index scans. Normally, `InnoDB' uses an algorithm called
     _next-key locking_ that combines index-row locking with gap
     locking. `InnoDB' performs row-level locking in such a way that
     when it searches or scans a table index, it sets shared or
     exclusive locks on the index records it encounters. Thus, the
     row-level locks are actually index-record locks. In addition, a
     next-key lock on an index record also affects the `gap' before
     that index record. That is, a next-key lock is an index-record
     lock plus a gap lock on the gap preceding the index record. If one
     session has a shared or exclusive lock on record `R' in an index,
     another session cannot insert a new index record in the gap
     immediately before `R' in the index order. See *Note
     innodb-record-level-locks::.

     By default, the value of `innodb_locks_unsafe_for_binlog' is 0
     (disabled), which means that gap locking is enabled: `InnoDB' uses
     next-key locks for searches and index scans. To enable the
     variable, set it to 1. This causes gap locking to be disabled:
     `InnoDB' uses only index-record locks for searches and index scans.

     Enabling `innodb_locks_unsafe_for_binlog' does not disable the use
     of gap locking for foreign-key constraint checking or
     duplicate-key checking.

     The effect of enabling `innodb_locks_unsafe_for_binlog' is similar
     to but not identical to setting the transaction isolation level to
     `READ COMMITTED':

        * Enabling `innodb_locks_unsafe_for_binlog' is a global setting
          and affects all sessions, whereas the isolation level can be
          set globally for all sessions, or individually per sesssion.

        * `innodb_locks_unsafe_for_binlog' can be set only at server
          startup, whereas the isolation level can be set at startup or
          changed at runtime.

     `READ COMMITTED' therefore offers finer and more flexible control
     than `innodb_locks_unsafe_for_binlog'.  For additional details
     about the effect of isolation level on gap locking, see *Note
     set-transaction::.

     Enabling `innodb_locks_unsafe_for_binlog' may cause phantom
     problems because other sessions can insert new rows into the gaps
     when gap locking is disabled. Suppose that there is an index on
     the `id' column of the `child' table and that you want to read and
     lock all rows from the table having an identifier value larger
     than 100, with the intention of updating some column in the
     selected rows later:

          SELECT * FROM child WHERE id > 100 FOR UPDATE;

     The query scans the index starting from the first record where
     `id' is greater than 100. If the locks set on the index records in
     that range do not lock out inserts made in the gaps, another
     session can insert a new row into the table. Consequently, if you
     were to execute the same *Note `SELECT': select. again within the
     same transaction, you would see a new row in the result set
     returned by the query. This also means that if new items are added
     to the database, `InnoDB' does not guarantee serializability.
     Therefore, if `innodb_locks_unsafe_for_binlog' is enabled,
     `InnoDB' guarantees at most an isolation level of `READ
     COMMITTED'. (Conflict serializability is still guaranteed.) For
     additional information about phantoms, see *Note
     innodb-next-key-locking::.

     Enabling `innodb_locks_unsafe_for_binlog' has additional effects:

        * For *Note `UPDATE': update. or *Note `DELETE': delete.
          statements, `InnoDB' holds locks only for rows that it
          updates or deletes. Record locks for non-matching rows are
          released after MySQL has evaluated the `WHERE' condition.
          This greatly reduces the probability of deadlocks, but they
          can still happen.

        * For *Note `UPDATE': update. statements, if a row is already
          locked, `InnoDB' performs a `semi-consistent' read, returning
          the latest committed version to MySQL so that MySQL can
          determine whether the row matches the `WHERE' condition of the
          *Note `UPDATE': update. If the row matches (must be updated),
          MySQL reads the row again and this time `InnoDB' either locks
          it or waits for a lock on it.

     Consider the following example, beginning with this table:

          CREATE TABLE t (a INT NOT NULL, b INT) ENGINE = InnoDB;
          INSERT INTO t VALUES (1,2),(2,3),(3,2),(4,3),(5,2);
          COMMIT;

     In this case, table has no indexes, so searches and index scans
     use the hidden clustered index for record locking (see *Note
     innodb-index-types::).

     Suppose that one client performs an *Note `UPDATE': update. using
     these statements:

          SET autocommit = 0;
          UPDATE t SET b = 5 WHERE b = 3;

     Suppose also that a second client performs an *Note `UPDATE':
     update. by executing these statements following those of the first
     client:

          SET autocommit = 0;
          UPDATE t SET b = 4 WHERE b = 2;

     As `InnoDB' executes each *Note `UPDATE': update, it first
     acquires an exclusive lock for each row, and then determines
     whether to modify it. If `InnoDB' does not modify the row and
     `innodb_locks_unsafe_for_binlog' is enabled, it releases the lock.
     Otherwise, `InnoDB' retains the lock until the end of the
     transaction. This affects transaction processing as follows.

     If `innodb_locks_unsafe_for_binlog' is disabled, the first *Note
     `UPDATE': update.  acquires x-locks and does not release any of
     them:

          x-lock(1,2); retain x-lock
          x-lock(2,3); update(2,3) to (2,5); retain x-lock
          x-lock(3,2); retain x-lock
          x-lock(4,3); update(4,3) to (4,5); retain x-lock
          x-lock(5,2); retain x-lock

     The second *Note `UPDATE': update. blocks as soon as it tries to
     acquire any locks (because first update has retained locks on all
     rows), and does not proceed until the first *Note `UPDATE':
     update. commits or rolls back:

          x-lock(1,2); block and wait for first UPDATE to commit or roll back

     If `innodb_locks_unsafe_for_binlog' is enabled, the first *Note
     `UPDATE': update.  acquires x-locks and releases those for rows
     that it does not modify:

          x-lock(1,2); unlock(1,2)
          x-lock(2,3); update(2,3) to (2,5); retain x-lock
          x-lock(3,2); unlock(3,2)
          x-lock(4,3); update(4,3) to (4,5); retain x-lock
          x-lock(5,2); unlock(5,2)

     For the second `UPDATE', `InnoDB' does a `semi-consistent' read,
     returning the latest committed version of each row to MySQL so
     that MySQL can determine whether the row matches the `WHERE'
     condition of the *Note `UPDATE': update.:

          x-lock(1,2); update(1,2) to (1,4); retain x-lock
          x-lock(2,3); unlock(2,3)
          x-lock(3,2); update(3,2) to (3,4); retain x-lock
          x-lock(4,3); unlock(4,3)
          x-lock(5,2); update(5,2) to (5,4); retain x-lock

   *  `innodb_log_buffer_size'

     The size in bytes of the buffer that `InnoDB' uses to write to the
     log files on disk. The default value is 1MB. Sensible values range
     from 1MB to 8MB. A large log buffer allows large transactions to
     run without a need to write the log to disk before the
     transactions commit. Thus, if you have big transactions, making
     the log buffer larger saves disk I/O.

   *  `innodb_log_file_size'

     The size in bytes of each log file in a log group. The combined
     size of log files must be less than 4GB. The default value is 5MB.
     Sensible values range from 1MB to 1/N-th of the size of the buffer
     pool, where N is the number of log files in the group. The larger
     the value, the less checkpoint flush activity is needed in the
     buffer pool, saving disk I/O.  But larger log files also mean that
     recovery is slower in case of a crash.

   *  `innodb_log_files_in_group'

     The number of log files in the log group.  `InnoDB' writes to the
     files in a circular fashion. The default (and recommended) value
     is 2.

   *  `innodb_log_group_home_dir'

     The directory path to the `InnoDB' log files.  If you do not
     specify any `InnoDB' log variables, the default is to create two
     5MB files names `ib_logfile0' and `ib_logfile1' in the MySQL data
     directory.

   *  `innodb_max_dirty_pages_pct'

     This is an integer in the range from 0 to 100. The default value
     is 90. The main thread in `InnoDB' tries to write pages from the
     buffer pool so that the percentage of dirty (not yet written)
     pages will not exceed this value.

   *  `innodb_max_purge_lag'

     This variable controls how to delay *Note `INSERT': insert, *Note
     `UPDATE': update, and *Note `DELETE': delete. operations when purge
     operations are lagging (see *Note innodb-multi-versioning::). The
     default value 0 (no delays).

     The `InnoDB' transaction system maintains a list of transactions
     that have delete-marked index records by *Note `UPDATE': update. or
     *Note `DELETE': delete. operations. Let the length of this list be
     PURGE_LAG.  When PURGE_LAG exceeds `innodb_max_purge_lag', each
     *Note `INSERT': insert, *Note `UPDATE': update, and *Note
     `DELETE': delete. operation is delayed by
     ((PURGE_LAG/`innodb_max_purge_lag')x10)-5 milliseconds. The delay
     is computed in the beginning of a purge batch, every ten seconds.
     The operations are not delayed if purge cannot run because of an
     old consistent read view that could see the rows to be purged.

     A typical setting for a problematic workload might be 1 million,
     assuming that transactions are small, only 100 bytes in size, and
     it is allowable to have 100MB of unpurged `InnoDB' table rows.

   *  `innodb_mirrored_log_groups'

     The number of identical copies of log groups to keep for the
     database. This should be set to 1.

   *  `innodb_open_files'

     This variable is relevant only if you use multiple tablespaces in
     `InnoDB'. It specifies the maximum number of `.ibd' files that
     `InnoDB' can keep open at one time. The minimum value is 10. The
     default value is 300.

     The file descriptors used for `.ibd' files are for `InnoDB' only.
     They are independent of those specified by the
     `--open-files-limit' server option, and do not affect the
     operation of the table cache.

   *  `innodb_rollback_on_timeout'

     In MySQL 6.0, `InnoDB' rolls back only the last statement on a
     transaction timeout by default. If `--innodb_rollback_on_timeout'
     is specified, a transaction timeout causes `InnoDB' to abort and
     roll back the entire transaction (the same behavior as in MySQL
     4.1).

   *  `innodb_stats_on_metadata'

     When this variable is enabled (which is the default, as before the
     variable was created), `InnoDB' updates statistics during metadata
     statements such as *Note `SHOW TABLE STATUS': show-table-status. or
     *Note `SHOW INDEX': show-index, or when accessing the
     `INFORMATION_SCHEMA' tables *Note `TABLES': tables-table. or *Note
     `STATISTICS': statistics-table. (These updates are similar to what
     happens for *Note `ANALYZE TABLE': analyze-table.) When disabled,
     `InnoDB' does not updates statistics during these operations.
     Disabling this variable can improve access speed for schemas that
     have a large number of tables or indexes. It can also improve the
     stability of execution plans for queries that involve `InnoDB'
     tables.

   *  `innodb_support_xa'

     When the variable is enabled (the default), `InnoDB' support for
     two-phase commit in XA transactions is enabled, which causes an
     extra disk flush for transaction preparation.

     If you do not wish to use XA transactions, you can disable this
     variable to reduce the number of disk flushes and get better
     `InnoDB' performance.

     Having `innodb_support_xa' enabled on a replication master -- or
     on any MySQL server where binary logging is in use -- ensures that
     the binary log does not get out of sync compared to the table data.

   *  `innodb_sync_spin_loops'

     The number of times a thread waits for an `InnoDB' mutex to be
     freed before the thread is suspended. The default value is 20.

   *  `innodb_table_locks'

     If `autocommit = 0', `InnoDB' honors *Note `LOCK TABLES':
     lock-tables.; MySQL does not return from `LOCK TABLES ... WRITE'
     until all other threads have released all their locks to the
     table. The default value of `innodb_table_locks' is 1, which means
     that *Note `LOCK TABLES': lock-tables.  causes InnoDB to lock a
     table internally if `autocommit = 0'.

   *  `innodb_thread_concurrency'

     `InnoDB' tries to keep the number of operating system threads
     concurrently inside `InnoDB' less than or equal to the limit given
     by this variable. Once the number of threads reaches this limit,
     additional threads are placed into a wait state within a FIFO
     queue for execution. Threads waiting for locks are not counted in
     the number of concurrently executing threads.

     The correct value for this variable is dependent on environment
     and workload. You will need to try a range of different values to
     determine what value works for your applications.

     The range of this variable is 0 to 1000. You can disable thread
     concurrency checking by setting the value to 0.  Disabling thread
     concurrency checking allows InnoDB to create as many threads as it
     needs.

     The default value is 8.

   *  `innodb_thread_sleep_delay'

     How long `InnoDB' threads sleep before joining the `InnoDB' queue,
     in microseconds.  The default value is 10,000. A value of 0
     disables sleep.

   * `sync_binlog'

     If the value of this variable is greater than 0, the MySQL server
     synchronizes its binary log to disk (using `fdatasync()') after
     every `sync_binlog' writes to the binary log. There is one write
     to the binary log per statement if autocommit is enabled, and one
     write per transaction otherwise. The default value of
     `sync_binlog' is 0, which does no synchronizing to disk. A value
     of 1 is the safest choice, because in the event of a crash you
     lose at most one statement or transaction from the binary log.
     However, it is also the slowest choice (unless the disk has a
     battery-backed cache, which makes synchronization very fast).


File: manual.info,  Node: using-innodb-tables,  Next: adding-and-removing,  Prev: innodb-parameters,  Up: innodb

13.7.4 Creating and Using `InnoDB' Tables
-----------------------------------------

* Menu:

* innodb-transactions-with-different-apis::  How to Use Transactions in `InnoDB' with Different APIs
* converting-tables-to-innodb::  Converting Tables from Other Storage Engines to `InnoDB'
* innodb-auto-increment-handling::  `AUTO_INCREMENT' Handling in `InnoDB'
* innodb-foreign-key-constraints::  `FOREIGN KEY' Constraints
* innodb-and-mysql-replication::  `InnoDB' and MySQL Replication

To create an `InnoDB' table, specify an `ENGINE = InnoDB' option in the
*Note `CREATE TABLE': create-table. statement:

     CREATE TABLE customers (a INT, b CHAR (20), INDEX (a)) ENGINE=InnoDB;

The statement creates a table and an index on column `a' in the
`InnoDB' tablespace that consists of the data files that you specified
in `my.cnf'. In addition, MySQL creates a file `customers.frm' in the
`test' directory under the MySQL database directory. Internally,
`InnoDB' adds an entry for the table to its own data dictionary. The
entry includes the database name. For example, if `test' is the
database in which the `customers' table is created, the entry is for
`'test/customers''.  This means you can create a table of the same name
`customers' in some other database, and the table names do not collide
inside `InnoDB'.

You can query the amount of free space in the `InnoDB' tablespace by
issuing a *Note `SHOW TABLE STATUS': show-table-status. statement for
any `InnoDB' table. The amount of free space in the tablespace appears
in the `Data_free' section in the output of *Note `SHOW TABLE STATUS':
show-table-status. (or the `Comment' section prior to MySQL 6.0.5). For
example:

     SHOW TABLE STATUS FROM test LIKE 'customers'

The statistics *Note `SHOW': show. displays for `InnoDB' tables are
only approximate. They are used in SQL optimization. Table and index
reserved sizes in bytes are accurate, though.


File: manual.info,  Node: innodb-transactions-with-different-apis,  Next: converting-tables-to-innodb,  Prev: using-innodb-tables,  Up: using-innodb-tables

13.7.4.1 How to Use Transactions in `InnoDB' with Different APIs
................................................................

By default, each client that connects to the MySQL server begins with
autocommit mode enabled, which automatically commits every SQL
statement as you execute it. To use multiple-statement transactions,
you can switch autocommit off with the SQL statement `SET autocommit =
0' and end each transaction with either *Note `COMMIT': commit. or
*Note `ROLLBACK': commit. If you want to leave autocommit on, you can
begin your transactions within *Note `START TRANSACTION': commit. and
end them with *Note `COMMIT': commit. or *Note `ROLLBACK': commit. The
following example shows two transactions. The first is committed; the
second is rolled back.

     shell> mysql test

     mysql> CREATE TABLE customer (a INT, b CHAR (20), INDEX (a))
         -> ENGINE=InnoDB;
     Query OK, 0 rows affected (0.00 sec)
     mysql> START TRANSACTION;
     Query OK, 0 rows affected (0.00 sec)
     mysql> INSERT INTO customer VALUES (10, 'Heikki');
     Query OK, 1 row affected (0.00 sec)
     mysql> COMMIT;
     Query OK, 0 rows affected (0.00 sec)
     mysql> SET autocommit=0;
     Query OK, 0 rows affected (0.00 sec)
     mysql> INSERT INTO customer VALUES (15, 'John');
     Query OK, 1 row affected (0.00 sec)
     mysql> ROLLBACK;
     Query OK, 0 rows affected (0.00 sec)
     mysql> SELECT * FROM customer;
     +------+--------+
     | a    | b      |
     +------+--------+
     |   10 | Heikki |
     +------+--------+
     1 row in set (0.00 sec)
     mysql>

In APIs such as PHP, Perl DBI, JDBC, ODBC, or the standard C call
interface of MySQL, you can send transaction control statements such as
*Note `COMMIT': commit. to the MySQL server as strings just like any
other SQL statements such as *Note `SELECT': select. or *Note `INSERT':
insert. Some APIs also offer separate special transaction commit and
rollback functions or methods.


File: manual.info,  Node: converting-tables-to-innodb,  Next: innodb-auto-increment-handling,  Prev: innodb-transactions-with-different-apis,  Up: using-innodb-tables

13.7.4.2 Converting Tables from Other Storage Engines to `InnoDB'
.................................................................

To convert a non-`InnoDB' table to use `InnoDB' use *Note `ALTER
TABLE': alter-table.:

     ALTER TABLE t1 ENGINE=InnoDB;

*Important*:

Do not convert MySQL system tables in the `mysql' database (such as
`user' or `host') to the `InnoDB' type. This is an unsupported
operation. The system tables must always be of the `MyISAM' type.

`InnoDB' does not have a special optimization for separate index
creation the way the `MyISAM' storage engine does. Therefore, it does
not pay to export and import the table and create indexes afterward.
The fastest way to alter a table to `InnoDB' is to do the inserts
directly to an `InnoDB' table. That is, use `ALTER TABLE ...
ENGINE=INNODB', or create an empty `InnoDB' table with identical
definitions and insert the rows with `INSERT INTO ... SELECT * FROM
...'.

If you have `UNIQUE' constraints on secondary keys, you can speed up a
table import by turning off the uniqueness checks temporarily during
the import operation:

     SET unique_checks=0;
     ... IMPORT OPERATION ...
     SET unique_checks=1;

For big tables, this saves a lot of disk I/O because `InnoDB' can then
use its insert buffer to write secondary index records as a batch. Be
certain that the data contains no duplicate keys.  `unique_checks'
allows but does not require storage engines to ignore duplicate keys.

To get better control over the insertion process, it might be good to
insert big tables in pieces:

     INSERT INTO newtable SELECT * FROM oldtable
        WHERE yourkey > something AND yourkey <= somethingelse;

After all records have been inserted, you can rename the tables.

During the conversion of big tables, you should increase the size of
the `InnoDB' buffer pool to reduce disk I/O. Do not use more than 80%
of the physical memory, though.  You can also increase the sizes of the
`InnoDB' log files.

Make sure that you do not fill up the tablespace: `InnoDB' tables
require a lot more disk space than `MyISAM' tables. If an *Note `ALTER
TABLE': alter-table. operation runs out of space, it starts a rollback,
and that can take hours if it is disk-bound. For inserts, `InnoDB' uses
the insert buffer to merge secondary index records to indexes in
batches. That saves a lot of disk I/O. For rollback, no such mechanism
is used, and the rollback can take 30 times longer than the insertion.

In the case of a runaway rollback, if you do not have valuable data in
your database, it may be advisable to kill the database process rather
than wait for millions of disk I/O operations to complete. For the
complete procedure, see *Note forcing-recovery::.

If you want all your (non-system) tables to be created as `InnoDB'
tables, add the line `default-storage-engine=innodb' to the `[mysqld]'
section of your server option file.


File: manual.info,  Node: innodb-auto-increment-handling,  Next: innodb-foreign-key-constraints,  Prev: converting-tables-to-innodb,  Up: using-innodb-tables

13.7.4.3 `AUTO_INCREMENT' Handling in `InnoDB'
..............................................

* Menu:

* innodb-auto-increment-traditional::  `Traditional' `InnoDB' Auto-Increment Locking
* innodb-auto-increment-configurable::  Configurable `InnoDB' Auto-Increment Locking

`InnoDB' provides a locking strategy that significantly improves
scalability and performance of SQL statements that add rows to tables
with `AUTO_INCREMENT' columns. This section provides background
information on the original (`traditional') implementation of
auto-increment locking in `InnoDB', explains the configurable locking
mechanism, documents the parameter for configuring the mechanism, and
describes its behavior and interaction with replication.


File: manual.info,  Node: innodb-auto-increment-traditional,  Next: innodb-auto-increment-configurable,  Prev: innodb-auto-increment-handling,  Up: innodb-auto-increment-handling

13.7.4.4 `Traditional' `InnoDB' Auto-Increment Locking
......................................................

The original implementation of auto-increment handling in `InnoDB' uses
the following strategy to prevent problems when using the binary log
for statement-based replication or for certain recovery scenarios.

If you specify an `AUTO_INCREMENT' column for an `InnoDB' table, the
table handle in the `InnoDB' data dictionary contains a special counter
called the auto-increment counter that is used in assigning new values
for the column. This counter is stored only in main memory, not on disk.

`InnoDB' uses the following algorithm to initialize the auto-increment
counter for a table `t' that contains an `AUTO_INCREMENT' column named
`ai_col': After a server startup, for the first insert into a table `t',
`InnoDB' executes the equivalent of this statement:

     SELECT MAX(ai_col) FROM t FOR UPDATE;

`InnoDB' increments by one the value retrieved by the statement and
assigns it to the column and to the auto-increment counter for the
table. If the table is empty, `InnoDB' uses the value `1'. If a user
invokes a *Note `SHOW TABLE STATUS': show-table-status. statement that
displays output for the table `t' and the auto-increment counter has
not been initialized, `InnoDB' initializes but does not increment the
value and stores it for use by later inserts. This initialization uses
a normal exclusive-locking read on the table and the lock lasts to the
end of the transaction.

`InnoDB' follows the same procedure for initializing the auto-increment
counter for a freshly created table.

After the auto-increment counter has been initialized, if a user does
not explicitly specify a value for an `AUTO_INCREMENT' column, `InnoDB'
increments the counter by one and assigns the new value to the column.
If the user inserts a row that explicitly specifies the column value,
and the value is bigger than the current counter value, the counter is
set to the specified column value.

When accessing the auto-increment counter, `InnoDB' uses a special
table-level `AUTO-INC' lock that it keeps to the end of the current SQL
statement, not to the end of the transaction.  The special lock release
strategy was introduced to improve concurrency for inserts into a table
containing an `AUTO_INCREMENT' column. Nevertheless, two transactions
cannot have the `AUTO-INC' lock on the same table simultaneously, which
can have a performance impact if the `AUTO-INC' lock is held for a long
time. That might be the case for a statement such as `INSERT INTO t1
... SELECT ... FROM t2' that inserts all rows from one table into
another.

`InnoDB' uses the in-memory auto-increment counter as long as the
server runs. When the server is stopped and restarted, `InnoDB'
reinitializes the counter for each table for the first *Note `INSERT':
insert. to the table, as described earlier.

You may see gaps in the sequence of values assigned to the
`AUTO_INCREMENT' column if you roll back transactions that have
generated numbers using the counter.

If a user specifies `NULL' or `0' for the `AUTO_INCREMENT' column in an
*Note `INSERT': insert, `InnoDB' treats the row as if the value had not
been specified and generates a new value for it.

The behavior of the auto-increment mechanism is not defined if a user
assigns a negative value to the column or if the value becomes bigger
than the maximum integer that can be stored in the specified integer
type.

An `AUTO_INCREMENT' column must appear as the first column in an index
on an `InnoDB' table.

`InnoDB' supports the `AUTO_INCREMENT = N' table option in *Note
`CREATE TABLE': create-table. and *Note `ALTER TABLE': alter-table.
statements, to set the initial counter value or alter the current
counter value.  The effect of this option is canceled by a server
restart, for reasons discussed earlier in this section.


File: manual.info,  Node: innodb-auto-increment-configurable,  Prev: innodb-auto-increment-traditional,  Up: innodb-auto-increment-handling

13.7.4.5 Configurable `InnoDB' Auto-Increment Locking
.....................................................

As described in the previous section, `InnoDB' uses a special lock
called the table-level `AUTO-INC' lock for inserts into tables with
`AUTO_INCREMENT' columns. This lock is normally held to the end of the
statement (not to the end of the transaction), to ensure that
auto-increment numbers are assigned in a predictable and repeatable
order for a given sequence of *Note `INSERT': insert. statements.

In the case of statement-based replication, this means that when an SQL
statement is replicated on a slave server, the same values are used for
the auto-increment column as on the master server. The result of
execution of multiple *Note `INSERT': insert. statements is
deterministic, and the slave reproduces the same data as on the master.
If auto-increment values generated by multiple *Note `INSERT': insert.
statements were interleaved, the result of two concurrent *Note
`INSERT': insert. statements would be non-deterministic, and could not
reliably be propagated to a slave server using statement-based
replication.

To make this clear, consider an example that uses this table:

     CREATE TABLE t1 (
       c1 INT(11) NOT NULL AUTO_INCREMENT,
       c2 VARCHAR(10) DEFAULT NULL,
       PRIMARY KEY (c1)
     ) ENGINE=InnoDB;

Suppose that there are two transactions running, each inserting rows
into a table with an `AUTO_INCREMENT' column. One transaction is using
an *Note `INSERT ... SELECT': insert-select. statement that inserts
1000 rows, and another is using a simple *Note `INSERT': insert.
statement that inserts one row:

     Tx1: INSERT INTO t1 (c2) SELECT 1000 rows from another table ...
     Tx2: INSERT INTO t1 (c2) VALUES ('xxx');

`InnoDB' cannot tell in advance how many rows will be retrieved from the
*Note `SELECT': select. in the *Note `INSERT': insert. statement in
Tx1, and it assigns the auto-increment values one at a time as the
statement proceeds. With a table-level lock, held to the end of the
statement, only one *Note `INSERT': insert. statement referring to
table `t1' can execute at a time, and the generation of auto-increment
numbers by different statements is not interleaved. The auto-increment
value generated by the Tx1 *Note `INSERT ... SELECT': insert-select.
statement will be consecutive, and the (single) auto-increment value
used by the *Note `INSERT': insert. statement in Tx2 will either be
smaller or larger than all those used for Tx1, depending on which
statement executes first.

As long as the SQL statements execute in the same order when replayed
from the binary log (when using statement-based replication, or in
recovery scenarios), the results will be the same as they were when Tx1
and Tx2 first ran. Thus, table-level locks held until the end of a
statement make *Note `INSERT': insert. statements using auto-increment
safe for use with statement-based replication.  However, those locks
limit concurrency and scalability when multiple transactions are
executing insert statements at the same time.

In the preceding example, if there were no table-level lock, the value
of the auto-increment column used for the *Note `INSERT': insert. in
Tx2 depends on precisely when the statement executes. If the *Note
`INSERT': insert. of Tx2 executes while the *Note `INSERT': insert. of
Tx1 is running (rather than before it starts or after it completes), the
specific auto-increment values assigned by the two *Note `INSERT':
insert. statements are non-deterministic, and may vary from run to run.

In MySQL 6.0, `InnoDB' can avoid using the table-level `AUTO-INC' lock
for a class of *Note `INSERT': insert. statements where the number of
rows is known in advance, and still preserve deterministic execution
and safety for statement-based replication. Further, if you are not
using the binary log to replay SQL statements as part of recovery or
replication, you can entirely eliminate use of the table-level
`AUTO-INC' lock for even greater concurrency and performance--at the
cost of permitting gaps in auto-increment numbers assigned by a
statement and potentially having the numbers assigned by concurrently
executing statements interleaved.

For *Note `INSERT': insert. statements where the number of rows to be
inserted is known at the beginning of processing the statement,
`InnoDB' quickly allocates the required number of auto-increment values
without taking any lock, but only if there is no concurrent session
already holding the table-level `AUTO-INC' lock (because that other
statement will be allocating auto-increment values one-by-one as it
proceeds). More precisely, such an *Note `INSERT': insert.  statement
obtains auto-increment values under the control of a mutex (a
light-weight lock) that is _not_ held until the statement completes,
but only for the duration of the allocation process.

This new locking scheme allows much greater scalability, but it does
introduce some subtle differences in how auto-increment values are
assigned compared to the original mechanism. To describe the way
auto-increment works in `InnoDB', the following discussion defines some
terms, and explains how `InnoDB' behaves using different settings of
the new `innodb_autoinc_lock_mode' configuration parameter. Additional
considerations are described following the explanation of
auto-increment locking behavior.

First, some definitions:

   * `*Note `INSERT': insert.-like' statements

     All statements that generate new rows in a table, including *Note
     `INSERT': insert, *Note `INSERT ... SELECT': insert-select, *Note
     `REPLACE': replace, `REPLACE ... SELECT', and *Note `LOAD DATA':
     load-data.

   * `Simple inserts'

     Statements for which the number of rows to be inserted can be
     determined in advance (when the statement is initially processed).
     This includes single-row and multiple-row *Note `INSERT': insert.
     and *Note `REPLACE': replace. statements that do not have a nested
     subquery, but not `INSERT ... ON DUPLICATE KEY UPDATE'.

   * `Bulk inserts'

     Statements for which the number of rows to be inserted (and the
     number of required auto-increment values) is not known in advance.
     This includes *Note `INSERT ... SELECT': insert-select, `REPLACE
     ... SELECT', and *Note `LOAD DATA': load-data. statements.
     `InnoDB' will assign new values for the `AUTO_INCREMENT' column
     one at a time as each row is processed.

   * `Mixed-mode inserts'

     These are `simple insert' statements that specify the
     auto-increment value for some (but not all) of the new rows. An
     example follows, where `c1' is an `AUTO_INCREMENT' column of table
     `t1':

          INSERT INTO t1 (c1,c2) VALUES (1,'a'), (NULL,'b'), (5,'c'), (NULL,'d');

     Another type of `mixed-mode insert' is `INSERT ... ON DUPLICATE
     KEY UPDATE', which in the worst case is in effect an *Note
     `INSERT': insert. followed by a *Note `UPDATE': update, where the
     allocated value for the `AUTO_INCREMENT' column may or may not be
     used during the update phase.

In MySQL 6.0, there is a new configuration parameter that controls how
`InnoDB' uses locking when generating values for `AUTO_INCREMENT'
columns. This parameter can be set using the
`--innodb-autoinc-lock-mode' option at *Note `mysqld': mysqld. startup.

In general, if you encounter problems with the way auto-increment works
(which will most likely involve replication), you can force use of the
original behavior by setting the lock mode to 0.

There are three possible settings for the `innodb_autoinc_lock_mode'
parameter:

   * `innodb_autoinc_lock_mode = 0' (`traditional' lock mode)

     This lock mode provides the same behavior as before
     `innodb_autoinc_lock_mode' existed. For all `*Note `INSERT':
     insert.-like' statements, a special table-level `AUTO-INC' lock is
     obtained and held to the end of the statement. This assures that
     the auto-increment values assigned by any given statement are
     consecutive (although `gaps' can exist within a table if a
     transaction that generated auto-increment values is rolled back,
     as discussed later).

     This lock mode is provided only for backward compatibility and
     performance testing. There is little reason to use this lock mode
     unless you use `mixed-mode inserts' and care about the important
     difference in semantics described later.

   * `innodb_autoinc_lock_mode = 1' (`consecutive' lock mode)

     This is the default lock mode. In this mode, `bulk inserts' use
     the special `AUTO-INC' table-level lock and hold it until the end
     of the statement. This applies to all *Note `INSERT ... SELECT':
     insert-select, `REPLACE ... SELECT', and *Note `LOAD DATA':
     load-data. statements.  Only one statement holding the `AUTO-INC'
     lock can execute at a time.

     With this lock mode, `simple inserts' (only) use a new locking
     model where a light-weight mutex is used during the allocation of
     auto-increment values, and no table-level `AUTO-INC' lock is used,
     unless an `AUTO-INC' lock is held by another transaction. If
     another transaction does hold an `AUTO-INC' lock, a `simple
     insert' waits for the `AUTO-INC' lock, as if it too were a `bulk
     insert.'

     This lock mode ensures that, in the presence of *Note `INSERT':
     insert. statements where the number of rows is not known in
     advance (and where auto-increment numbers are assigned as the
     statement progresses), all auto-increment values assigned by any
     `*Note `INSERT': insert.-like' statement are consecutive, and
     operations are safe for statement-based replication.

     Simply put, the important impact of this lock mode is
     significantly better scalability. This mode is safe for use with
     statement-based replication. Further, as with `traditional' lock
     mode, auto-increment numbers assigned by any given statement are
     _consecutive_. In this mode, there is _no change_ in semantics
     compared to `traditional' mode for any statement that uses
     auto-increment, with one important exception.

     The exception is for `mixed-mode inserts', where the user provides
     explicit values for an `AUTO_INCREMENT' column for some, but not
     all, rows in a multiple-row `simple insert.' For such inserts,
     `InnoDB' will allocate more auto-increment values than the number
     of rows to be inserted. However, all values automatically assigned
     are consecutively generated (and thus higher than) the
     auto-increment value generated by the most recently executed
     previous statement. `Excess' numbers are lost.

     A similar situation exists if you use `INSERT ...  ON DUPLICATE
     KEY UPDATE'. This statement is also classified as a `mixed-mode
     insert' since an auto-increment value is not necessarily generated
     for each row. Because `InnoDB' allocates the auto-increment value
     before the insert is actually attempted, it cannot know whether an
     inserted value will be a duplicate of an existing value and thus
     cannot know whether the auto-increment value it generates will be
     used for a new row. Therefore, if you are using statement-based
     replication, you must either avoid `INSERT ... ON DUPLICATE KEY
     UPDATE' or use `innodb_autoinc_lock_mode = 0' (`traditional' lock
     mode).

   * `innodb_autoinc_lock_mode = 2' (`interleaved' lock mode)

     In this lock mode, no `*Note `INSERT': insert.-like' statements
     use the table-level `AUTO-INC' lock, and multiple statements can
     execute at the same time. This is the fastest and most scalable
     lock mode, but it is _not safe_ when using statement-based
     replication or recovery scenarios when SQL statements are replayed
     from the binary log.

     In this lock mode, auto-increment values are guaranteed to be
     unique and monotonically increasing across all concurrently
     executing `*Note `INSERT': insert.-like' statements. However,
     because multiple statements can be generating numbers at the same
     time (that is, allocation of numbers is _interleaved_ across
     statements), the values generated for the rows inserted by any
     given statement may not be consecutive.

     If the only statements executing are `simple inserts' where the
     number of rows to be inserted is known ahead of time, there will
     be no gaps in the numbers generated for a single statement, except
     for `mixed-mode inserts.' However, when `bulk inserts' are
     executed, there may be gaps in the auto-increment values assigned
     by any given statement.

The auto-increment locking modes provided by `innodb_autoinc_lock_mode'
have several usage implications:

   * Using auto-increment with replication

     If you are using statement-based replication, you should set
     `innodb_autoinc_lock_mode' to 0 or 1 and use the same value on the
     master and its slaves. Auto-increment values are not ensured to be
     the same on the slaves as on the master if you use
     `innodb_autoinc_lock_mode' = 2 (`interleaved') or configurations
     where the master and slaves do not use the same lock mode.

     If you are using row-based replication, all of the auto-increment
     lock modes are safe. Row-based replication is not sensitive to the
     order of execution of the SQL statements.

   * `Lost' auto-increment values and sequence gaps

     In all lock modes (0, 1, and 2), if a transaction that generated
     auto-increment values rolls back, those auto-increment values are
     `lost.' Once a value is generated for an auto-increment column, it
     cannot be rolled back, whether or not the `*Note `INSERT':
     insert.-like' statement is completed, and whether or not the
     containing transaction is rolled back. Such lost values are not
     reused. Thus, there may be gaps in the values stored in an
     `AUTO_INCREMENT' column of a table.

   * Auto-increment values assigned by `mixed-mode inserts'

     Consider a `mixed-mode insert,' where a `simple insert' specifies
     the auto-increment value for some (but not all) resulting rows.
     Such a statement will behave differently in lock modes 0, 1, and
     2. For example, assume `c1' is an `AUTO_INCREMENT' column of table
     `t1', and that the most recent automatically generated sequence
     number is 100. Consider the following `mixed-mode insert'
     statement:

          INSERT INTO t1 (c1,c2) VALUES (1,'a'), (NULL,'b'), (5,'c'), (NULL,'d');

     With `innodb_autoinc_lock_mode' set to 0 (`traditional'), the four
     new rows will be:

          +-----+------+
          | c1  | c2   |
          +-----+------+
          |   1 | a    |
          | 101 | b    |
          |   5 | c    |
          | 102 | d    |
          +-----+------+

     The next available auto-increment value will be 103 because the
     auto-increment values are allocated one at a time, not all at once
     at the beginning of statement execution. This result is true
     whether or not there are concurrently executing `*Note `INSERT':
     insert.-like' statements (of any type).

     With `innodb_autoinc_lock_mode' set to 1 (`consecutive'), the four
     new rows will also be:

          +-----+------+
          | c1  | c2   |
          +-----+------+
          |   1 | a    |
          | 101 | b    |
          |   5 | c    |
          | 102 | d    |
          +-----+------+

     However, in this case, the next available auto-increment value
     will be 105, not 103 because four auto-increment values are
     allocated at the time the statement is processed, but only two are
     used. This result is true whether or not there are concurrently
     executing `*Note `INSERT': insert.-like' statements (of any type).

     With `innodb_autoinc_lock_mode' set to mode 2 (`interleaved'), the
     four new rows will be:

          +-----+------+
          | c1  | c2   |
          +-----+------+
          |   1 | a    |
          |   X | b    |
          |   5 | c    |
          |   Y | d    |
          +-----+------+

     The values of X and Y will be unique and larger than any
     previously generated rows. However, the specific values of X and Y
     will depend on the number of auto-increment values generated by
     concurrently executing statements.

     Finally, consider the following statement, issued when the
     most-recently generated sequence number was the value 4:

          INSERT INTO t1 (c1,c2) VALUES (1,'a'), (NULL,'b'), (5,'c'), (NULL,'d');

     With any `innodb_autoinc_lock_mode' setting, this statement will
     generate a duplicate-key error 23000 (`Can't write; duplicate key
     in table') because 5 will be allocated for the row `(NULL, 'b')'
     and insertion of the row `(5, 'c')' will fail.

   * Gaps in auto-increment values for `bulk inserts'

     With `innodb_autoinc_lock_mode' set to 0 (`traditional') or 1
     (`consecutive'), the auto-increment values generated by any given
     statement will be consecutive, without gaps, because the
     table-level `AUTO-INC' lock is held until the end of the
     statement, and only one such statement can execute at a time.

     With `innodb_autoinc_lock_mode' set to 2 (`interleaved'), there
     may be gaps in the auto-increment values generated by `bulk
     inserts,' but only if there are concurrently executing `*Note
     `INSERT': insert.-like' statements.


File: manual.info,  Node: innodb-foreign-key-constraints,  Next: innodb-and-mysql-replication,  Prev: innodb-auto-increment-handling,  Up: using-innodb-tables

13.7.4.6 `FOREIGN KEY' Constraints
..................................

`InnoDB' supports foreign key constraints. The syntax for a foreign key
constraint definition in `InnoDB' looks like this:

     [CONSTRAINT [SYMBOL]] FOREIGN KEY
         [INDEX_NAME] (INDEX_COL_NAME, ...)
         REFERENCES TBL_NAME (INDEX_COL_NAME,...)
         [ON DELETE REFERENCE_OPTION]
         [ON UPDATE REFERENCE_OPTION]

     REFERENCE_OPTION:
         RESTRICT | CASCADE | SET NULL | NO ACTION

INDEX_NAME represents a foreign key ID. If given, this is ignored if an
index for the foreign key is defined explicitly. Otherwise, if `InnoDB'
creates an index for the foreign key, it uses INDEX_NAME for the index
name.

Foreign keys definitions are subject to the following conditions:

   * Both tables must be `InnoDB' tables and they must not be
     `TEMPORARY' tables.

   * Corresponding columns in the foreign key and the referenced key
     must have similar internal data types inside `InnoDB' so that they
     can be compared without a type conversion. _The size and sign of
     integer types must be the same_. The length of string types need
     not be the same. For non-binary (character) string columns, the
     character set and collation must be the same.

   * `InnoDB' requires indexes on foreign keys and referenced keys so
     that foreign key checks can be fast and not require a table scan.
     In the referencing table, there must be an index where the foreign
     key columns are listed as the _first_ columns in the same order.
     Such an index is created on the referencing table automatically if
     it does not exist. (This is in contrast to some older versions, in
     which indexes had to be created explicitly or the creation of
     foreign key constraints would fail.) INDEX_NAME, if given, is used
     as described previously.

   * `InnoDB' allows a foreign key to reference any index column or
     group of columns. However, in the referenced table, there must be
     an index where the referenced columns are listed as the _first_
     columns in the same order.

   * Index prefixes on foreign key columns are not supported. One
     consequence of this is that *Note `BLOB': blob. and *Note `TEXT':
     blob. columns cannot be included in a foreign key because indexes
     on those columns must always include a prefix length.

   * If the `CONSTRAINT SYMBOL' clause is given, the SYMBOL value must
     be unique in the database. If the clause is not given, `InnoDB'
     creates the name automatically.

`InnoDB' rejects any *Note `INSERT': insert. or *Note `UPDATE': update.
operation that attempts to create a foreign key value in a child table
if there is no a matching candidate key value in the parent table. The
action `InnoDB' takes for any *Note `UPDATE': update. or *Note
`DELETE': delete. operation that attempts to update or delete a
candidate key value in the parent table that has some matching rows in
the child table is dependent on the _referential action_ specified using
`ON UPDATE' and `ON DELETE' subclauses of the `FOREIGN KEY' clause. When
the user attempts to delete or update a row from a parent table, and
there are one or more matching rows in the child table, `InnoDB'
supports five options regarding the action to be taken. If `ON DELETE'
or `ON UPDATE' are not specified, the default action is `RESTRICT'.

   * `CASCADE': Delete or update the row from the parent table and
     automatically delete or update the matching rows in the child
     table. Both `ON DELETE CASCADE' and `ON UPDATE CASCADE' are
     supported. Between two tables, you should not define several `ON
     UPDATE CASCADE' clauses that act on the same column in the parent
     table or in the child table.

     *Note*:

     Currently, cascaded foreign key actions to not activate triggers.

   * `SET NULL': Delete or update the row from the parent table and set
     the foreign key column or columns in the child table to `NULL'.
     This is valid only if the foreign key columns do not have the `NOT
     NULL' qualifier specified. Both `ON DELETE SET NULL' and `ON
     UPDATE SET NULL' clauses are supported.

     If you specify a `SET NULL' action, _make sure that you have not
     declared the columns in the child table as `NOT NULL'_.

   * `NO ACTION': In standard SQL, `NO ACTION' means _no action_ in the
     sense that an attempt to delete or update a primary key value is
     not allowed to proceed if there is a related foreign key value in
     the referenced table.  `InnoDB' rejects the delete or update
     operation for the parent table.

   * `RESTRICT': Rejects the delete or update operation for the parent
     table. Specifying `RESTRICT' (or `NO ACTION') is the same as
     omitting the `ON DELETE' or `ON UPDATE' clause.  (Some database
     systems have deferred checks, and `NO ACTION' is a deferred check.
     In MySQL, foreign key constraints are checked immediately, so `NO
     ACTION' is the same as `RESTRICT'.)

   * `SET DEFAULT': This action is recognized by the parser, but
     `InnoDB' rejects table definitions containing `ON DELETE SET
     DEFAULT' or `ON UPDATE SET DEFAULT' clauses.

`InnoDB' supports foreign key references within a table. In these
cases, `child table records' really refers to dependent records within
the same table.

Here is a simple example that relates `parent' and `child' tables
through a single-column foreign key:

     CREATE TABLE parent (id INT NOT NULL,
                          PRIMARY KEY (id)
     ) ENGINE=INNODB;
     CREATE TABLE child (id INT, parent_id INT,
                         INDEX par_ind (parent_id),
                         FOREIGN KEY (parent_id) REFERENCES parent(id)
                           ON DELETE CASCADE
     ) ENGINE=INNODB;

A more complex example in which a `product_order' table has foreign
keys for two other tables. One foreign key references a two-column
index in the `product' table. The other references a single-column
index in the `customer' table:

     CREATE TABLE product (category INT NOT NULL, id INT NOT NULL,
                           price DECIMAL,
                           PRIMARY KEY(category, id)) ENGINE=INNODB;
     CREATE TABLE customer (id INT NOT NULL,
                            PRIMARY KEY (id)) ENGINE=INNODB;
     CREATE TABLE product_order (no INT NOT NULL AUTO_INCREMENT,
                                 product_category INT NOT NULL,
                                 product_id INT NOT NULL,
                                 customer_id INT NOT NULL,
                                 PRIMARY KEY(no),
                                 INDEX (product_category, product_id),
                                 FOREIGN KEY (product_category, product_id)
                                   REFERENCES product(category, id)
                                   ON UPDATE CASCADE ON DELETE RESTRICT,
                                 INDEX (customer_id),
                                 FOREIGN KEY (customer_id)
                                   REFERENCES customer(id)) ENGINE=INNODB;

`InnoDB' allows you to add a new foreign key constraint to a table by
using *Note `ALTER TABLE': alter-table.:

     ALTER TABLE TBL_NAME
         ADD [CONSTRAINT [SYMBOL]] FOREIGN KEY
         [INDEX_NAME] (INDEX_COL_NAME, ...)
         REFERENCES TBL_NAME (INDEX_COL_NAME,...)
         [ON DELETE REFERENCE_OPTION]
         [ON UPDATE REFERENCE_OPTION]

The foreign key can be self referential (referring to the same table).
When you add a foreign key constraint to a table using *Note `ALTER
TABLE': alter-table, _remember to create the required indexes first._

`InnoDB' supports the use of *Note `ALTER TABLE': alter-table. to drop
foreign keys:

     ALTER TABLE TBL_NAME DROP FOREIGN KEY FK_SYMBOL;

If the `FOREIGN KEY' clause included a `CONSTRAINT' name when you
created the foreign key, you can refer to that name to drop the foreign
key.  Otherwise, the FK_SYMBOL value is internally generated by
`InnoDB' when the foreign key is created. To find out the symbol value
when you want to drop a foreign key, use the *Note `SHOW CREATE TABLE':
show-create-table. statement. For example:

     mysql> SHOW CREATE TABLE ibtest11c\G
     *************************** 1. row ***************************
            Table: ibtest11c
     Create Table: CREATE TABLE `ibtest11c` (
       `A` int(11) NOT NULL auto_increment,
       `D` int(11) NOT NULL default '0',
       `B` varchar(200) NOT NULL default '',
       `C` varchar(175) default NULL,
       PRIMARY KEY  (`A`,`D`,`B`),
       KEY `B` (`B`,`C`),
       KEY `C` (`C`),
       CONSTRAINT `0_38775` FOREIGN KEY (`A`, `D`)
     REFERENCES `ibtest11a` (`A`, `D`)
     ON DELETE CASCADE ON UPDATE CASCADE,
       CONSTRAINT `0_38776` FOREIGN KEY (`B`, `C`)
     REFERENCES `ibtest11a` (`B`, `C`)
     ON DELETE CASCADE ON UPDATE CASCADE
     ) ENGINE=INNODB CHARSET=latin1
     1 row in set (0.01 sec)

     mysql> ALTER TABLE ibtest11c DROP FOREIGN KEY `0_38775`;

You cannot add a foreign key and drop a foreign key in separate clauses
of a single *Note `ALTER TABLE': alter-table.  statement. Separate
statements are required.

If *Note `ALTER TABLE': alter-table. for an `InnoDB' table results in
changes to column values (for example, because a column is truncated),
`InnoDB''s `FOREIGN KEY' constraint checks do not notice possible
violations caused by changing the values.

The `InnoDB' parser allows table and column identifiers in a `FOREIGN
KEY ... REFERENCES ...' clause to be quoted within backticks.
(Alternatively, double quotes can be used if the `ANSI_QUOTES' SQL mode
is enabled.) The `InnoDB' parser also takes into account the setting of
the `lower_case_table_names' system variable.

`InnoDB' returns a table's foreign key definitions as part of the
output of the *Note `SHOW CREATE TABLE': show-create-table. statement:

     SHOW CREATE TABLE TBL_NAME;

*Note `mysqldump': mysqldump. also produces correct definitions of
tables in the dump file, and does not forget about the foreign keys.

You can also display the foreign key constraints for a table like this:

     SHOW TABLE STATUS FROM DB_NAME LIKE 'TBL_NAME';

The foreign key constraints are listed in the `Comment' column of the
output.

When performing foreign key checks, `InnoDB' sets shared row-level
locks on child or parent records it has to look at. `InnoDB' checks
foreign key constraints immediately; the check is not deferred to
transaction commit.

To make it easier to reload dump files for tables that have foreign key
relationships, *Note `mysqldump': mysqldump.  automatically includes a
statement in the dump output to set `foreign_key_checks' to 0. This
avoids problems with tables having to be reloaded in a particular order
when the dump is reloaded. It is also possible to set this variable
manually:

     mysql> SET foreign_key_checks = 0;
     mysql> SOURCE DUMP_FILE_NAME;
     mysql> SET foreign_key_checks = 1;

This allows you to import the tables in any order if the dump file
contains tables that are not correctly ordered for foreign keys. It
also speeds up the import operation. Setting `foreign_key_checks' to 0
can also be useful for ignoring foreign key constraints during *Note
`LOAD DATA': load-data. and *Note `ALTER TABLE': alter-table.
operations. However, even if `foreign_key_checks = 0', InnoDB does not
allow the creation of a foreign key constraint where a column
references a non-matching column type. Also, if an `InnoDB' table has
foreign key constraints, *Note `ALTER TABLE': alter-table. cannot be
used to change the table to use another storage engine. To alter the
storage engine, you must drop any foreign key constraints first.

`InnoDB' does not allow you to drop a table that is referenced by a
`FOREIGN KEY' constraint, unless you do `SET foreign_key_checks = 0'.
When you drop a table, the constraints that were defined in its create
statement are also dropped.

If you re-create a table that was dropped, it must have a definition
that conforms to the foreign key constraints referencing it. It must
have the right column names and types, and it must have indexes on the
referenced keys, as stated earlier. If these are not satisfied, MySQL
returns error number 1005 and refers to error 150 in the error message.

If MySQL reports an error number 1005 from a *Note `CREATE TABLE':
create-table. statement, and the error message refers to error 150,
table creation failed because a foreign key constraint was not
correctly formed. Similarly, if an *Note `ALTER TABLE': alter-table.
fails and it refers to error 150, that means a foreign key definition
would be incorrectly formed for the altered table. You can use *Note
`SHOW ENGINE INNODB STATUS': show-engine. to display a detailed
explanation of the most recent `InnoDB' foreign key error in the server.

*Important*:

For users familiar with the ANSI/ISO SQL Standard, please note that no
storage engine, including `InnoDB', recognizes or enforces the `MATCH'
clause used in referential-integrity constraint definitions. Use of an
explicit `MATCH' clause will not have the specified effect, and also
causes `ON DELETE' and `ON UPDATE' clauses to be ignored. For these
reasons, specifying `MATCH' should be avoided.

The `MATCH' clause in the SQL standard controls how `NULL' values in a
composite (multiple-column) foreign key are handled when comparing to a
primary key. `InnoDB' essentially implements the semantics defined by
`MATCH SIMPLE', which allow a foreign key to be all or partially
`NULL'. In that case, the (child table) row containing such a foreign
key is allowed to be inserted, and does not match any row in the
referenced (parent) table. It is possible to implement other semantics
using triggers.

Additionally, MySQL and `InnoDB' require that the referenced columns be
indexed for performance. However, the system does not enforce a
requirement that the referenced columns be `UNIQUE' or be declared `NOT
NULL'. The handling of foreign key references to non-unique keys or
keys that contain `NULL' values is not well defined for operations such
as *Note `UPDATE': update. or `DELETE CASCADE'. You are advised to use
foreign keys that reference only `UNIQUE' and `NOT NULL' keys.

Furthermore, `InnoDB' does not recognize or support `inline `REFERENCES'
specifications' (as defined in the SQL standard) where the references
are defined as part of the column specification. `InnoDB' accepts
`REFERENCES' clauses only when specified as part of a separate `FOREIGN
KEY' specification. For other storage engines, MySQL Server parses and
ignores foreign key specifications.

*Deviation from SQL standards*: If there are several rows in the parent
table that have the same referenced key value, `InnoDB' acts in foreign
key checks as if the other parent rows with the same key value do not
exist. For example, if you have defined a `RESTRICT' type constraint,
and there is a child row with several parent rows, `InnoDB' does not
allow the deletion of any of those parent rows.

`InnoDB' performs cascading operations through a depth-first algorithm,
based on records in the indexes corresponding to the foreign key
constraints.

*Deviation from SQL standards*: A `FOREIGN KEY' constraint that
references a non-`UNIQUE' key is not standard SQL. It is an `InnoDB'
extension to standard SQL.

*Deviation from SQL standards*: If `ON UPDATE CASCADE' or `ON UPDATE
SET NULL' recurses to update the _same table_ it has previously updated
during the cascade, it acts like `RESTRICT'. This means that you cannot
use self-referential `ON UPDATE CASCADE' or `ON UPDATE SET NULL'
operations. This is to prevent infinite loops resulting from cascaded
updates. A self-referential `ON DELETE SET NULL', on the other hand, is
possible, as is a self-referential `ON DELETE CASCADE'. Cascading
operations may not be nested more than 15 levels deep.

*Deviation from SQL standards*: Like MySQL in general, in an SQL
statement that inserts, deletes, or updates many rows, `InnoDB' checks
`UNIQUE' and `FOREIGN KEY' constraints row-by-row. According to the SQL
standard, the default behavior should be deferred checking. That is,
constraints are only checked after the _entire SQL statement_ has been
processed. Until `InnoDB' implements deferred constraint checking, some
things will be impossible, such as deleting a record that refers to
itself via a foreign key.


File: manual.info,  Node: innodb-and-mysql-replication,  Prev: innodb-foreign-key-constraints,  Up: using-innodb-tables

13.7.4.7 `InnoDB' and MySQL Replication
.......................................

MySQL replication works for `InnoDB' tables as it does for `MyISAM'
tables. It is also possible to use replication in a way where the
storage engine on the slave is not the same as the original storage
engine on the master. For example, you can replicate modifications to an
`InnoDB' table on the master to a `MyISAM' table on the slave.

To set up a new slave for a master, you have to make a copy of the
`InnoDB' tablespace and the log files, as well as the `.frm' files of
the `InnoDB' tables, and move the copies to the slave. If the
`innodb_file_per_table' variable is enabled, you must also copy the
`.ibd' files as well. For the proper procedure to do this, see *Note
innodb-backup::.

If you can shut down the master or an existing slave, you can take a
cold backup of the `InnoDB' tablespace and log files and use that to
set up a slave. To make a new slave without taking down any server you
can also use the commercial `InnoDB' Hot Backup tool
(http://www.innodb.com/hot-backup).

Transactions that fail on the master do not affect replication at all.
MySQL replication is based on the binary log where MySQL writes SQL
statements that modify data. A transaction that fails (for example,
because of a foreign key violation, or because it is rolled back) is
not written to the binary log, so it is not sent to slaves. See *Note
commit::.

Replication and `CASCADE'

Cascading actions for `InnoDB' tables on the master are replicated on
the slave _only_ if the tables sharing the foreign key relation use
`InnoDB' on both the master and slave. This is true whether you are
using statement-based or row-based replication. For example, suppose
you have started replication, and then create two tables on the master
using the following *Note `CREATE TABLE': create-table.  statements:

     CREATE TABLE fc1 (
         i INT PRIMARY KEY,
         j INT
     ) ENGINE = InnoDB;

     CREATE TABLE fc2 (
         m INT PRIMARY KEY,
         n INT,
         FOREIGN KEY ni (n) REFERENCES fc1 (i)
             ON DELETE CASCADE
     ) ENGINE = InnoDB;

Suppose that the slave does not have `InnoDB' support enabled. If this
is the case, then the tables on the slave are created, but they use the
`MyISAM' storage engine, and the `FOREIGN KEY' option is ignored. Now
we insert some rows into the tables on the master:

     master> INSERT INTO fc1 VALUES (1, 1), (2, 2);
     Query OK, 2 rows affected (0.09 sec)
     Records: 2  Duplicates: 0  Warnings: 0

     master> INSERT INTO fc2 VALUES (1, 1), (2, 2), (3, 1);
     Query OK, 3 rows affected (0.19 sec)
     Records: 3  Duplicates: 0  Warnings: 0

At this point, on both the master and the slave, table `fc1' contains 2
rows, and table `fc2' contains 3 rows, as shown here:

     master> SELECT * FROM fc1;
     +---+------+
     | i | j    |
     +---+------+
     | 1 |    1 |
     | 2 |    2 |
     +---+------+
     2 rows in set (0.00 sec)

     master> SELECT * FROM fc2;
     +---+------+
     | m | n    |
     +---+------+
     | 1 |    1 |
     | 2 |    2 |
     | 3 |    1 |
     +---+------+
     3 rows in set (0.00 sec)

     slave> SELECT * FROM fc1;
     +---+------+
     | i | j    |
     +---+------+
     | 1 |    1 |
     | 2 |    2 |
     +---+------+
     2 rows in set (0.00 sec)

     slave> SELECT * FROM fc2;
     +---+------+
     | m | n    |
     +---+------+
     | 1 |    1 |
     | 2 |    2 |
     | 3 |    1 |
     +---+------+
     3 rows in set (0.00 sec)

Now suppose that you perform the following *Note `DELETE': delete.
statement on the master:

     master> DELETE FROM fc1 WHERE i=1;
     Query OK, 1 row affected (0.09 sec)

Due to the cascade, table `fc2' on the master now contains only 1 row:

     master> SELECT * FROM fc2;
     +---+---+
     | m | n |
     +---+---+
     | 2 | 2 |
     +---+---+
     1 row in set (0.00 sec)

However, the cascade does not propagate on the slave because on the
slave the *Note `DELETE': delete. for `fc1' deletes no rows from `fc2'.
The slave's copy of `fc2' still contains all of the rows that were
originally inserted:

     slave> SELECT * FROM fc2;
     +---+---+
     | m | n |
     +---+---+
     | 1 | 1 |
     | 3 | 1 |
     | 2 | 2 |
     +---+---+
     3 rows in set (0.00 sec)

This difference is due to the fact that the cascading deletes are
handled internally by the `InnoDB' storage engine, which means that
none of the changes are logged.


File: manual.info,  Node: adding-and-removing,  Next: innodb-backup,  Prev: using-innodb-tables,  Up: innodb

13.7.5 Adding, Removing, or Resizing `InnoDB' Data and Log Files
----------------------------------------------------------------

This section describes what you can do when your `InnoDB' tablespace
runs out of room or when you want to change the size of the log files.

The easiest way to increase the size of the `InnoDB' tablespace is to
configure it from the beginning to be auto-extending. Specify the
`autoextend' attribute for the last data file in the tablespace
definition. Then `InnoDB' increases the size of that file automatically
in 8MB increments when it runs out of space. The increment size can be
changed by setting the value of the `innodb_autoextend_increment'
system variable, which is measured in MB.

Alternatively, you can increase the size of your tablespace by adding
another data file. To do this, you have to shut down the MySQL server,
change the tablespace configuration to add a new data file to the end of
`innodb_data_file_path', and start the server again.

If your last data file was defined with the keyword `autoextend', the
procedure for reconfiguring the tablespace must take into account the
size to which the last data file has grown. Obtain the size of the data
file, round it down to the closest multiple of 1024 x 1024 bytes (=
1MB), and specify the rounded size explicitly in
`innodb_data_file_path'. Then you can add another data file. Remember
that only the last data file in the `innodb_data_file_path' can be
specified as auto-extending.

As an example, assume that the tablespace has just one auto-extending
data file `ibdata1':

     innodb_data_home_dir =
     innodb_data_file_path = /ibdata/ibdata1:10M:autoextend

Suppose that this data file, over time, has grown to 988MB. Here is the
configuration line after modifying the original data file to not be
auto-extending and adding another auto-extending data file:

     innodb_data_home_dir =
     innodb_data_file_path = /ibdata/ibdata1:988M;/disk2/ibdata2:50M:autoextend

When you add a new file to the tablespace configuration, make sure that
it does not exist. `InnoDB' will create and initialize the file when
you restart the server.

Currently, you cannot remove a data file from the tablespace. To
decrease the size of your tablespace, use this procedure:

  1. Use *Note `mysqldump': mysqldump. to dump all your `InnoDB' tables.

  2. Stop the server.

  3. Remove all the existing tablespace files, including the `ibdata'
     and `ib_log' files. If you want to keep a backup copy of the
     information, then copy all the `ib*' files to another location
     before the removing the files in your MySQL installation.

  4. Remove any `.frm' files for `InnoDB' tables.

  5. Configure a new tablespace.

  6. Restart the server.

  7. Import the dump files.

If you want to change the number or the size of your `InnoDB' log
files, use the following instructions. The procedure to use depends on
the value of `innodb_fast_shutdown':

   * If `innodb_fast_shutdown' is not set to 2: Stop the MySQL server
     and make sure that it shuts down without errors (to ensure that
     there is no information for outstanding transactions in the log).
     Copy the old log files into a safe place in case something went
     wrong during the shutdown and you need them to recover the
     tablespace. Delete the old log files from the log file directory,
     edit `my.cnf' to change the log file configuration, and start the
     MySQL server again.  *Note `mysqld': mysqld. sees that no `InnoDB'
     log files exist at startup and creates new ones.

   * If `innodb_fast_shutdown' is set to 2: Shut down the server, set
     `innodb_fast_shutdown' to 1, and restart the server. The server
     should be allowed to recover. Then you should shut down the server
     again and follow the procedure described in the preceding item to
     change `InnoDB' log file size. Set `innodb_fast_shutdown' back to
     2 and restart the server.


File: manual.info,  Node: innodb-backup,  Next: moving,  Prev: adding-and-removing,  Up: innodb

13.7.6 Backing Up and Recovering an `InnoDB' Database
-----------------------------------------------------

* Menu:

* forcing-recovery::             Forcing `InnoDB' Recovery
* innodb-checkpoints::           `InnoDB' Checkpoints

The key to safe database management is making regular backups.

`InnoDB Hot Backup' enables you to back up a running MySQL database,
including `InnoDB' and `MyISAM' tables, with minimal disruption to
operations while producing a consistent snapshot of the database.  When
`InnoDB Hot Backup' is copying `InnoDB' tables, reads and writes to both
`InnoDB' and `MyISAM' tables can continue. During the copying of
`MyISAM' tables, reads (but not writes) to those tables are permitted.
In addition, `InnoDB Hot Backup' supports creating compressed backup
files, and performing backups of subsets of `InnoDB' tables. In
conjunction with MySQL's binary log, users can perform point-in-time
recovery.  `InnoDB Hot Backup' is commercially licensed by Innobase Oy.
For a more complete description of `InnoDB Hot Backup', see
`http://www.innodb.com/hot-backup/features/' or download the
documentation from `http://www.innodb.com/doc/hot_backup/manual.html'.
You can order trial, term, and perpetual licenses from Innobase at
`http://www.innodb.com/hot-backup/order/'.

If you are able to shut down your MySQL server, you can make a binary
backup that consists of all files used by `InnoDB' to manage its
tables. Use the following procedure:

  1. Shut down your MySQL server and make sure that it shuts down
     without errors.

  2. Copy all your data files (`ibdata' files and `.ibd' files) into a
     safe place.

  3. Copy all your `ib_logfile' files to a safe place.

  4. Copy your `my.cnf' configuration file or files to a safe place.

  5. Copy all the `.frm' files for your `InnoDB' tables to a safe place.

Replication works with `InnoDB' tables, so you can use MySQL
replication capabilities to keep a copy of your database at database
sites requiring high availability.

In addition to making binary backups as just described, you should also
regularly make dumps of your tables with *Note `mysqldump': mysqldump.
The reason for this is that a binary file might be corrupted without
you noticing it. Dumped tables are stored into text files that are
human-readable, so spotting table corruption becomes easier. Also,
because the format is simpler, the chance for serious data corruption
is smaller.  *Note `mysqldump': mysqldump. also has a
`--single-transaction' option that you can use to make a consistent
snapshot without locking out other clients. See *Note backup-policy::.

To be able to recover your `InnoDB' database to the present from the
binary backup just described, you have to run your MySQL server with
binary logging turned on. To achieve point-in-time recovery after
restoring a backup, you can apply changes from the binary log that
occurred after the backup was made. See See *Note
point-in-time-recovery::.

To recover from a crash of your MySQL server, the only requirement is
to restart it. `InnoDB' automatically checks the logs and performs a
roll-forward of the database to the present. `InnoDB' automatically
rolls back uncommitted transactions that were present at the time of the
crash. During recovery, *Note `mysqld': mysqld. displays output
something like this:

     InnoDB: Database was not shut down normally.
     InnoDB: Starting recovery from log files...
     InnoDB: Starting log scan based on checkpoint at
     InnoDB: log sequence number 0 13674004
     InnoDB: Doing recovery: scanned up to log sequence number 0 13739520
     InnoDB: Doing recovery: scanned up to log sequence number 0 13805056
     InnoDB: Doing recovery: scanned up to log sequence number 0 13870592
     InnoDB: Doing recovery: scanned up to log sequence number 0 13936128
     ...
     InnoDB: Doing recovery: scanned up to log sequence number 0 20555264
     InnoDB: Doing recovery: scanned up to log sequence number 0 20620800
     InnoDB: Doing recovery: scanned up to log sequence number 0 20664692
     InnoDB: 1 uncommitted transaction(s) which must be rolled back
     InnoDB: Starting rollback of uncommitted transactions
     InnoDB: Rolling back trx no 16745
     InnoDB: Rolling back of trx no 16745 completed
     InnoDB: Rollback of uncommitted transactions completed
     InnoDB: Starting an apply batch of log records to the database...
     InnoDB: Apply batch completed
     InnoDB: Started
     mysqld: ready for connections

If your database gets corrupted or your disk fails, you have to do the
recovery from a backup. In the case of corruption, you should first
find a backup that is not corrupted. After restoring the base backup,
do the recovery from the binary log files using *Note `mysqlbinlog':
mysqlbinlog. and *Note `mysql': mysql. to restore the changes that
occurred after the backup was made.

In some cases of database corruption it is enough just to dump, drop,
and re-create one or a few corrupt tables. You can use the *Note `CHECK
TABLE': check-table. SQL statement to check whether a table is corrupt,
although *Note `CHECK TABLE': check-table. naturally cannot detect
every possible kind of corruption. You can use the Tablespace Monitor
to check the integrity of the file space management inside the
tablespace files.

In some cases, apparent database page corruption is actually due to the
operating system corrupting its own file cache, and the data on disk
may be okay. It is best first to try restarting your computer. Doing so
may eliminate errors that appeared to be database page corruption.


File: manual.info,  Node: forcing-recovery,  Next: innodb-checkpoints,  Prev: innodb-backup,  Up: innodb-backup

13.7.6.1 Forcing `InnoDB' Recovery
..................................

If there is database page corruption, you may want to dump your tables
from the database with `SELECT INTO ...  OUTFILE'. Usually, most of the
data obtained in this way is intact. However, it is possible that the
corruption might cause `SELECT * FROM TBL_NAME' statements or `InnoDB'
background operations to crash or assert, or even cause `InnoDB'
roll-forward recovery to crash. In such cases, you can use the
`innodb_force_recovery' option to force the `InnoDB' storage engine to
start up while preventing background operations from running, so that
you are able to dump your tables. For example, you can add the
following line to the `[mysqld]' section of your option file before
restarting the server:

     [mysqld]
     innodb_force_recovery = 4

`innodb_force_recovery' is 0 by default (normal startup without forced
recovery) The allowable non-zero values for `innodb_force_recovery'
follow. A larger number includes all precautions of smaller numbers. If
you are able to dump your tables with an option value of at most 4,
then you are relatively safe that only some data on corrupt individual
pages is lost. A value of 6 is more drastic because database pages are
left in an obsolete state, which in turn may introduce more corruption
into B-trees and other database structures.

   * `1' (`SRV_FORCE_IGNORE_CORRUPT')

     Let the server run even if it detects a corrupt page. Try to make
     `SELECT * FROM TBL_NAME' jump over corrupt index records and
     pages, which helps in dumping tables.

   * `2' (`SRV_FORCE_NO_BACKGROUND')

     Prevent the main thread from running. If a crash would occur
     during the purge operation, this recovery value prevents it.

   * `3' (`SRV_FORCE_NO_TRX_UNDO')

     Do not run transaction rollbacks after recovery.

   * `4' (`SRV_FORCE_NO_IBUF_MERGE')

     Prevent insert buffer merge operations. If they would cause a
     crash, do not do them. Do not calculate table statistics.

   * `5' (`SRV_FORCE_NO_UNDO_LOG_SCAN')

     Do not look at undo logs when starting the database: `InnoDB'
     treats even incomplete transactions as committed.

   * `6' (`SRV_FORCE_NO_LOG_REDO')

     Do not do the log roll-forward in connection with recovery.

_The database must not otherwise be used with any non-zero value of
`innodb_force_recovery'_.  As a safety measure, `InnoDB' prevents users
from performing *Note `INSERT': insert, *Note `UPDATE': update, or
*Note `DELETE': delete. operations when `innodb_force_recovery' is
greater than 0.

You can *Note `SELECT': select. from tables to dump them, or `DROP' or
`CREATE' tables even if forced recovery is used. If you know that a
given table is causing a crash on rollback, you can drop it. You can
also use this to stop a runaway rollback caused by a failing mass
import or *Note `ALTER TABLE': alter-table. You can kill the *Note
`mysqld': mysqld. process and set `innodb_force_recovery' to `3' to
bring the database up without the rollback, then `DROP' the table that
is causing the runaway rollback.


File: manual.info,  Node: innodb-checkpoints,  Prev: forcing-recovery,  Up: innodb-backup

13.7.6.2 `InnoDB' Checkpoints
.............................

`InnoDB' implements a checkpoint mechanism known as `fuzzy'
checkpointing.  `InnoDB' flushes modified database pages from the
buffer pool in small batches. There is no need to flush the buffer pool
in one single batch, which would in practice stop processing of user
SQL statements during the checkpointing process.

During crash recovery, `InnoDB' looks for a checkpoint label written to
the log files. It knows that all modifications to the database before
the label are present in the disk image of the database. Then `InnoDB'
scans the log files forward from the checkpoint, applying the logged
modifications to the database.

`InnoDB' writes to its log files on a rotating basis. All committed
modifications that make the database pages in the buffer pool different
from the images on disk must be available in the log files in case
`InnoDB' has to do a recovery. This means that when `InnoDB' starts to
reuse a log file, it has to make sure that the database page images on
disk contain the modifications logged in the log file that `InnoDB' is
going to reuse.  In other words, `InnoDB' must create a checkpoint and
this often involves flushing of modified database pages to disk.

The preceding description explains why making your log files very large
may reduce disk I/O in checkpointing. It often makes sense to set the
total size of the log files as large as the buffer pool or even larger.
The disadvantage of using large log files is that crash recovery can
take longer because there is more logged information to apply to the
database.


File: manual.info,  Node: moving,  Next: innodb-transaction-model,  Prev: innodb-backup,  Up: innodb

13.7.7 Moving an `InnoDB' Database to Another Machine
-----------------------------------------------------

On Windows, `InnoDB' always stores database and table names internally
in lowercase. To move databases in a binary format from Unix to Windows
or from Windows to Unix, you should create all databases and tables
using lowercase names. A convenient way to accomplish this is to add
the following line to the `[mysqld]' section of your `my.cnf' or
`my.ini' file before creating any databases or tables:

     [mysqld]
     lower_case_table_names=1

Like `MyISAM' data files, `InnoDB' data and log files are
binary-compatible on all platforms having the same floating-point
number format. You can move an `InnoDB' database simply by copying all
the relevant files listed in *Note innodb-backup::.  If the
floating-point formats differ but you have not used *Note `FLOAT':
numeric-types. or *Note `DOUBLE': numeric-types. data types in your
tables, then the procedure is the same: simply copy the relevant files.
If you use *Note `mysqldump': mysqldump. to dump your tables on one
machine and then import the dump files on the other machine, it does
not matter whether the formats differ or your tables contain
floating-point data.

One way to increase performance is to switch off autocommit mode when
importing data, assuming that the tablespace has enough space for the
big rollback segment that the import transactions generate. Do the
commit only after importing a whole table or a segment of a table.


File: manual.info,  Node: innodb-transaction-model,  Next: innodb-multi-versioning,  Prev: moving,  Up: innodb

13.7.8 The `InnoDB' Transaction Model and Locking
-------------------------------------------------

* Menu:

* innodb-lock-modes::            `InnoDB' Lock Modes
* innodb-consistent-read::       Consistent Non-Locking Reads
* innodb-locking-reads::         `SELECT ... FOR UPDATE' and `SELECT ... LOCK IN SHARE MODE' Locking Reads
* innodb-record-level-locks::    `InnoDB' Record, Gap, and Next-Key Locks
* innodb-next-key-locking::      Avoiding the Phantom Problem Using Next-Key Locking
* innodb-locks-set::             Locks Set by Different SQL Statements in `InnoDB'
* innodb-implicit-commit::       Implicit Transaction Commit and Rollback
* innodb-deadlock-detection::    Deadlock Detection and Rollback
* innodb-deadlocks::             How to Cope with Deadlocks

In the `InnoDB' transaction model, the goal is to combine the best
properties of a multi-versioning database with traditional two-phase
locking. `InnoDB' does locking on the row level and runs queries as
non-locking consistent reads by default, in the style of Oracle. The
lock table in `InnoDB' is stored so space-efficiently that lock
escalation is not needed: Typically several users are allowed to lock
every row in `InnoDB' tables, or any random subset of the rows, without
causing `InnoDB' memory exhaustion.

In `InnoDB', all user activity occurs inside a transaction. If
autocommit mode is enabled, each SQL statement forms a single
transaction on its own. By default, MySQL starts the session for each
new connection with autocommit enabled, so MySQL does a commit after
each SQL statement if that statement did not return an error. If a
statement returns an error, the commit or rollback behavior depends on
the error. See *Note innodb-error-handling::.

A session that has autocommit enabled can perform a multiple-statement
transaction by starting it with an explicit *Note `START TRANSACTION':
commit. or *Note `BEGIN': commit. statement and ending it with a *Note
`COMMIT': commit. or *Note `ROLLBACK': commit.  statement.

If autocommit mode is disabled within a session with `SET autocommit =
0', the session always has a transaction open. A *Note `COMMIT':
commit. or *Note `ROLLBACK': commit.  statement ends the current
transaction and a new one starts.

A *Note `COMMIT': commit. means that the changes made in the current
transaction are made permanent and become visible to other sessions. A
*Note `ROLLBACK': commit.  statement, on the other hand, cancels all
modifications made by the current transaction. Both *Note `COMMIT':
commit. and *Note `ROLLBACK': commit. release all `InnoDB' locks that
were set during the current transaction.

In terms of the SQL:1992 transaction isolation levels, the default
`InnoDB' level is `REPEATABLE READ'.  `InnoDB' offers all four
transaction isolation levels described by the SQL standard: `READ
UNCOMMITTED', `READ COMMITTED', `REPEATABLE READ', and `SERIALIZABLE'.

A user can change the isolation level for a single session or for all
subsequent connections with the *Note `SET TRANSACTION':
set-transaction. statement. To set the server's default isolation level
for all connections, use the `--transaction-isolation' option on the
command line or in an option file. For detailed information about
isolation levels and level-setting syntax, see *Note set-transaction::.

In row-level locking, `InnoDB' normally uses next-key locking. That
means that besides index records, `InnoDB' can also lock the `gap'
preceding an index record to block insertions by other sessions in the
gap immediately before the index record. A next-key lock refers to a
lock that locks an index record and the gap before it.  A gap lock
refers to a lock that locks only the gap before some index record.

For more information about row-level locking, and the circumstances
under which gap locking is disabled, see *Note
innodb-record-level-locks::.


File: manual.info,  Node: innodb-lock-modes,  Next: innodb-consistent-read,  Prev: innodb-transaction-model,  Up: innodb-transaction-model

13.7.8.1 `InnoDB' Lock Modes
............................

`InnoDB' implements standard row-level locking where there are two
types of locks:

   * A shared (S) lock allows a transaction to read a row.

   * An exclusive (X) lock allows a transaction to update or delete a
     row.

If transaction `T1' holds a shared (S) lock on row `r', then requests
from some distinct transaction `T2' for a lock on row `r' are handled
as follows:

   * A request by `T2' for an S lock can be granted immediately. As a
     result, both `T1' and `T2' hold an S lock on `r'.

   * A request by `T2' for an X lock cannot be granted immediately.

If a transaction `T1' holds an exclusive (X) lock on row `r', a request
from some distinct transaction `T2' for a lock of either type on `r'
cannot be granted immediately. Instead, transaction `T2' has to wait
for transaction `T1' to release its lock on row `r'.

Additionally, `InnoDB' supports _multiple granularity locking_ which
allows coexistence of record locks and locks on entire tables. To make
locking at multiple granularity levels practical, additional types of
locks called _intention locks_ are used. Intention locks are table
locks in `InnoDB'. The idea behind intention locks is for a transaction
to indicate which type of lock (shared or exclusive) it will require
later for a row in that table. There are two types of intention locks
used in `InnoDB' (assume that transaction `T' has requested a lock of
the indicated type on table `t'):

   * Intention shared (IS): Transaction `T' intends to set S locks on
     individual rows in table `t'.

   * Intention exclusive (IX): Transaction `T' intends to set X locks
     on those rows.

For example, *Note `SELECT ... LOCK IN SHARE MODE': select. sets an IS
lock and *Note `SELECT ... FOR UPDATE': select. sets an IX lock.

The intention locking protocol is as follows:

   * Before a transaction can acquire an S lock on a row in table `t',
     it must first acquire an IS or stronger lock on `t'.

   * Before a transaction can acquire an X lock on a row, it must first
     acquire an IX lock on `t'.

These rules can be conveniently summarized by means of the following
_lock type compatibility matrix_.

               X              IX             S              IS
X              Conflict       Conflict       Conflict       Conflict
IX             Conflict       Compatible     Conflict       Compatible
S              Conflict       Conflict       Compatible     Compatible
IS             Conflict       Compatible     Compatible     Compatible

A lock is granted to a requesting transaction if it is compatible with
existing locks, but not if it conflicts with existing locks. A
transaction waits until the conflicting existing lock is released. If a
lock request conflicts with an existing lock and cannot be granted
because it would cause deadlock, an error occurs.

Thus, intention locks do not block anything except full table requests
(for example, `LOCK TABLES ...  WRITE'). The main purpose of IX and IS
locks is to show that someone is locking a row, or going to lock a row
in the table.

The following example illustrates how an error can occur when a lock
request would cause a deadlock. The example involves two clients, A and
B.

First, client A creates a table containing one row, and then begins a
transaction. Within the transaction, A obtains an S lock on the row by
selecting it in share mode:

     mysql> CREATE TABLE t (i INT) ENGINE = InnoDB;
     Query OK, 0 rows affected (1.07 sec)

     mysql> INSERT INTO t (i) VALUES(1);
     Query OK, 1 row affected (0.09 sec)

     mysql> START TRANSACTION;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT * FROM t WHERE i = 1 LOCK IN SHARE MODE;
     +------+
     | i    |
     +------+
     |    1 |
     +------+
     1 row in set (0.10 sec)

Next, client B begins a transaction and attempts to delete the row from
the table:

     mysql> START TRANSACTION;
     Query OK, 0 rows affected (0.00 sec)

     mysql> DELETE FROM t WHERE i = 1;

The delete operation requires an X lock. The lock cannot be granted
because it is incompatible with the S lock that client A holds, so the
request goes on the queue of lock requests for the row and client B
blocks.

Finally, client A also attempts to delete the row from the table:

     mysql> DELETE FROM t WHERE i = 1;
     ERROR 1213 (40001): Deadlock found when trying to get lock;
     try restarting transaction

Deadlock occurs here because client A needs an X lock to delete the
row. However, that lock request cannot be granted because client B
already has a request for an X lock and is waiting for client A to
release its S lock. Nor can the S lock held by A be upgraded to an X
lock because of the prior request by B for an X lock. As a result,
`InnoDB' generates an error for client A and releases its locks. At
that point, the lock request for client B can be granted and B deletes
the row from the table.


File: manual.info,  Node: innodb-consistent-read,  Next: innodb-locking-reads,  Prev: innodb-lock-modes,  Up: innodb-transaction-model

13.7.8.2 Consistent Non-Locking Reads
.....................................

A consistent read means that `InnoDB' uses multi-versioning to present
to a query a snapshot of the database at a point in time. The query
sees the changes made by transactions that committed before that point
of time, and no changes made by later or uncommitted transactions. The
exception to this rule is that the query sees the changes made by
earlier statements within the same transaction. This exception causes
the following anomaly: If you update some rows in a table, a *Note
`SELECT': select. will see the latest version of the updated rows, but
it might also see older versions of any rows. If other sessions
simultaneously update the same table, the anomaly means that you may
see the table in a state that never existed in the database.

If the transaction isolation level is `REPEATABLE READ' (the default
level), all consistent reads within the same transaction read the
snapshot established by the first such read in that transaction. You
can get a fresher snapshot for your queries by committing the current
transaction and after that issuing new queries.

With `READ COMMITTED' isolation level, each consistent read within a
transaction sets and reads its own fresh snapshot.

Consistent read is the default mode in which `InnoDB' processes *Note
`SELECT': select. statements in `READ COMMITTED' and `REPEATABLE READ'
isolation levels. A consistent read does not set any locks on the tables
it accesses, and therefore other sessions are free to modify those
tables at the same time a consistent read is being performed on the
table.

Suppose that you are running in the default `REPEATABLE READ' isolation
level. When you issue a consistent read (that is, an ordinary *Note
`SELECT': select. statement), `InnoDB' gives your transaction a
timepoint according to which your query sees the database. If another
transaction deletes a row and commits after your timepoint was
assigned, you do not see the row as having been deleted. Inserts and
updates are treated similarly.

You can advance your timepoint by committing your transaction and then
doing another *Note `SELECT': select.

This is called _multi-versioned concurrency control_.

In the following example, session A sees the row inserted by B only
when B has committed the insert and A has committed as well, so that
the timepoint is advanced past the commit of B.

                  Session A              Session B

                SET autocommit=0;      SET autocommit=0;
     time
     |          SELECT * FROM t;
     |          empty set
     |                                 INSERT INTO t VALUES (1, 2);
     |
     v          SELECT * FROM t;
                empty set
                                       COMMIT;

                SELECT * FROM t;
                empty set

                COMMIT;

                SELECT * FROM t;
                ---------------------
                |    1    |    2    |
                ---------------------
                1 row in set

If you want to see the `freshest' state of the database, you should use
either the `READ COMMITTED' isolation level or a locking read:

     SELECT * FROM t LOCK IN SHARE MODE;

With `READ COMMITTED' isolation level, each consistent read within a
transaction sets and reads its own fresh snapshot. With `LOCK IN SHARE
MODE', a locking read occurs instead: A `SELECT' blocks until the
transaction containing the freshest rows ends (see *Note
innodb-locking-reads::).

Consistent read does not work over *Note `DROP TABLE': drop-table. or
over *Note `ALTER TABLE': alter-table.:

   * Consistent read does not work over *Note `DROP TABLE': drop-table.
     because MySQL cannot use a table that has been dropped and
     `InnoDB' destroys the table.

   * Consistent read does not work over *Note `ALTER TABLE':
     alter-table. because *Note `ALTER TABLE': alter-table. works by
     making a temporary copy of the original table and deleting the
     original table when the temporary copy is built. When you reissue
     a consistent read within a transaction, rows in the new table are
     not visible because those rows did not exist when the
     transaction's snapshot was taken.

`InnoDB' uses a consistent read for select in clauses like *Note
`INSERT INTO ... SELECT': insert, *Note `UPDATE ... (SELECT)': update,
and *Note `CREATE TABLE ... SELECT': create-table. that do not specify
`FOR UPDATE' or `LOCK IN SHARE MODE' if the
`innodb_locks_unsafe_for_binlog' option is set and the isolation level
of the transaction is not set to `SERIALIZABLE'. Thus, no locks are set
on rows read from the selected table. Otherwise, `InnoDB' uses stronger
locks and the *Note `SELECT': select. part acts like `READ COMMITTED',
where each consistent read, even within the same transaction, sets and
reads its own fresh snapshot.


File: manual.info,  Node: innodb-locking-reads,  Next: innodb-record-level-locks,  Prev: innodb-consistent-read,  Up: innodb-transaction-model

13.7.8.3 `SELECT ... FOR UPDATE' and `SELECT ... LOCK IN SHARE MODE' Locking Reads
..................................................................................

In some circumstances, a consistent (non-locking) read is not
convenient and a locking read is required instead.  `InnoDB' supports
two types of locking reads:

   * *Note `SELECT ... LOCK IN SHARE MODE': select. sets a shared mode
     lock on the rows read. A shared mode lock enables other sessions
     to read the rows but not to modify them. The rows read are the
     latest available, so if they belong to another transaction that has
     not yet committed, the read blocks until that transaction ends.

   * *Note `SELECT ... FOR UPDATE': select. sets an exclusive lock on
     the rows read. An exclusive lock prevents other sessions from
     accessing the rows for reading or writing.

Locks set by `LOCK IN SHARE MODE' and `FOR UPDATE' reads are released
when the transaction is committed or rolled back.

As an example of a situation in which a locking read is useful, suppose
that you want to insert a new row into a table `child', and make sure
that the child row has a parent row in table `parent'. The following
discussion describes how to implement referential integrity in
application code.

Suppose that you use a consistent read to read the table `parent' and
indeed see the parent row of the to-be-inserted child row in the table.
Can you safely insert the child row to table `child'? No, because it is
possible for some other session to delete the parent row from the table
`parent' in the meantime without you being aware of it.

The solution is to perform the *Note `SELECT': select. in a locking
mode using `LOCK IN SHARE MODE':

     SELECT * FROM parent WHERE NAME = 'Jones' LOCK IN SHARE MODE;

A read performed with `LOCK IN SHARE MODE' reads the latest available
data and sets a shared mode lock on the rows read. A shared mode lock
prevents others from updating or deleting the row read. Also, if the
latest data belongs to a yet uncommitted transaction of another
session, we wait until that transaction ends. After we see that the
`LOCK IN SHARE MODE' query returns the parent `'Jones'', we can safely
add the child record to the `child' table and commit our transaction.

Let us look at another example: We have an integer counter field in a
table `child_codes' that we use to assign a unique identifier to each
child added to table `child'. It is not a good idea to use either
consistent read or a shared mode read to read the present value of the
counter because two users of the database may then see the same value
for the counter, and a duplicate-key error occurs if two users attempt
to add children with the same identifier to the table.

Here, `LOCK IN SHARE MODE' is not a good solution because if two users
read the counter at the same time, at least one of them ends up in
deadlock when it attempts to update the counter.

In this case, there are two good ways to implement reading and
incrementing the counter:

   * First update the counter by incrementing it by 1, and then read it.

   * First perform a locking read of the counter using `FOR UPDATE',
     and then increment the counter.

The latter approach can be implemented as follows:

     SELECT counter_field FROM child_codes FOR UPDATE;
     UPDATE child_codes SET counter_field = counter_field + 1;

A *Note `SELECT ... FOR UPDATE': select. reads the latest available
data, setting exclusive locks on each row it reads. Thus, it sets the
same locks a searched SQL *Note `UPDATE': update. would set on the rows.

The preceding description is merely an example of how *Note `SELECT ...
FOR UPDATE': select. works. In MySQL, the specific task of generating a
unique identifier actually can be accomplished using only a single
access to the table:

     UPDATE child_codes SET counter_field = LAST_INSERT_ID(counter_field + 1);
     SELECT LAST_INSERT_ID();

The *Note `SELECT': select. statement merely retrieves the identifier
information (specific to the current connection). It does not access
any table.

*Note*:

Locking of rows for update using `SELECT FOR UPDATE' only applies when
autocommit is disabled (either by beginning transaction with *Note
`START TRANSACTION': commit. or by setting `autocommit' to 0. If
autocommit is enabled, the rows matching the specification are not
locked.


File: manual.info,  Node: innodb-record-level-locks,  Next: innodb-next-key-locking,  Prev: innodb-locking-reads,  Up: innodb-transaction-model

13.7.8.4 `InnoDB' Record, Gap, and Next-Key Locks
.................................................

`InnoDB' has several types of record-level locks:

   * Record lock: This is a lock on an index record.

   * Gap lock: This is a lock on a gap between index records, or a lock
     on the gap before the first or after the last index record.

   * Next-key lock: This is a combination of a record lock on the index
     record and a gap lock on the gap before the index record.

Record locks always lock index records, even if a table is defined with
no indexes. For such cases, `InnoDB' creates a hidden clustered index
and uses this index for record locking. See *Note innodb-index-types::.

By default, `InnoDB' operates in `REPEATABLE READ' transaction
isolation level and with the `innodb_locks_unsafe_for_binlog' system
variable disabled. In this case, `InnoDB' uses next-key locks for
searches and index scans, which prevents phantom rows (see *Note
innodb-next-key-locking::).

Next-key locking combines index-row locking with gap locking.  `InnoDB'
performs row-level locking in such a way that when it searches or scans
a table index, it sets shared or exclusive locks on the index records
it encounters. Thus, the row-level locks are actually index-record
locks. In addition, a next-key lock on an index record also affects the
`gap' before that index record. That is, a next-key lock is an
index-record lock plus a gap lock on the gap preceding the index
record. If one session has a shared or exclusive lock on record `R' in
an index, another session cannot insert a new index record in the gap
immediately before `R' in the index order.

Suppose that an index contains the values 10, 11, 13, and 20.  The
possible next-key locks for this index cover the following intervals,
where `(' or `)' denote exclusion of the interval endpoint and `[' or
`]' denote inclusion of the endpoint:

     (negative infinity, 10]
     (10, 11]
     (11, 13]
     (13, 20]
     (20, positive infinity)

For the last interval, the next-key lock locks the gap above the
largest value in the index and the `supremum' pseudo-record having a
value higher than any value actually in the index. The supremum is not
a real index record, so, in effect, this next-key lock locks only the
gap following the largest index value.

The preceding example shows that a gap might span a single index value,
multiple index values, or even be empty.

Gap locking is not needed for statements that lock rows using a unique
index to search for a unique row. For example, if the `id' column has a
unique index, the following statement uses only an index-record lock
for the row having `id' value 100 and it does not matter whether other
sessions insert rows in the preceding gap:

     SELECT * FROM child WHERE id = 100;

If `id' is not indexed or has a non-unique index, the statement does
lock the preceding gap.

A type of gap lock called an insertion intention gap lock is set by
*Note `INSERT': insert. operations prior to row insertion. This lock
signals the intent to insert in such a way that multiple transactions
inserting into the same index gap need not wait for each other if they
are not inserting at the same position within the gap. Suppose that
there are index records with values of 4 and 7. Separate transactions
that attempt to insert values of 5 and 6 each lock the gap between 4
and 7 with insert intention locks prior to obtaining the exclusive lock
on the inserted row, but do not block each other because the rows are
non-conflicting.

Gap locking can be disabled explicitly. This occurs if you change the
transaction isolation level to `READ COMMITTED' or enable the
`innodb_locks_unsafe_for_binlog' system variable. Under these
circumstances, gap locking is disabled for searches and index scans and
is used only for foreign-key constraint checking and duplicate-key
checking.

There are also other effects of using the `READ COMMITTED' isolation
level or enabling `innodb_locks_unsafe_for_binlog': Record locks for
non-matching rows are released after MySQL has evaluated the `WHERE'
condition. For `UPDATE' statements, `InnoDB' does a `semi-consistent'
read, such that it returns the latest committed version to MySQL so
that MySQL can determine whether the row matches the `WHERE' condition
of the *Note `UPDATE': update.


File: manual.info,  Node: innodb-next-key-locking,  Next: innodb-locks-set,  Prev: innodb-record-level-locks,  Up: innodb-transaction-model

13.7.8.5 Avoiding the Phantom Problem Using Next-Key Locking
............................................................

The so-called _phantom_ problem occurs within a transaction when the
same query produces different sets of rows at different times. For
example, if a *Note `SELECT': select. is executed twice, but returns a
row the second time that was not returned the first time, the row is a
`phantom' row.

Suppose that there is an index on the `id' column of the `child' table
and that you want to read and lock all rows from the table having an
identifier value larger than 100, with the intention of updating some
column in the selected rows later:

     SELECT * FROM child WHERE id > 100 FOR UPDATE;

The query scans the index starting from the first record where `id' is
bigger than 100. Let the table contain rows having `id' values of 90
and 102. If the locks set on the index records in the scanned range do
not lock out inserts made in the gaps (in this case, the gap between 90
and 102), another session can insert a new row into the table with an
`id' of 101. If you were to execute the same *Note `SELECT': select.
within the same transaction, you would see a new row with an `id' of
101 (a `phantom') in the result set returned by the query. If we regard
a set of rows as a data item, the new phantom child would violate the
isolation principle of transactions that a transaction should be able to
run so that the data it has read does not change during the transaction.

To prevent phantoms, `InnoDB' uses an algorithm called _next-key
locking_ that combines index-row locking with gap locking. `InnoDB'
performs row-level locking in such a way that when it searches or scans
a table index, it sets shared or exclusive locks on the index records
it encounters. Thus, the row-level locks are actually index-record
locks. In addition, a next-key lock on an index record also affects the
`gap' before that index record. That is, a next-key lock is an
index-record lock plus a gap lock on the gap preceding the index
record. If one session has a shared or exclusive lock on record `R' in
an index, another session cannot insert a new index record in the gap
immediately before `R' in the index order.

When `InnoDB' scans an index, it can also lock the gap after the last
record in the index. Just that happens in the preceding example: To
prevent any insert into the table where `id' would be bigger than 100,
the locks set by `InnoDB' include a lock on the gap following `id'
value 102.

You can use next-key locking to implement a uniqueness check in your
application: If you read your data in share mode and do not see a
duplicate for a row you are going to insert, then you can safely insert
your row and know that the next-key lock set on the successor of your
row during the read prevents anyone meanwhile inserting a duplicate for
your row. Thus, the next-key locking allows you to `lock' the
non-existence of something in your table.

Gap locking can be disabled as discussed in *Note
innodb-record-level-locks::. This may cause phantom problems because
other sessions can insert new rows into the gaps when gap locking is
disabled.


File: manual.info,  Node: innodb-locks-set,  Next: innodb-implicit-commit,  Prev: innodb-next-key-locking,  Up: innodb-transaction-model

13.7.8.6 Locks Set by Different SQL Statements in `InnoDB'
..........................................................

A locking read, an *Note `UPDATE': update, or a *Note `DELETE': delete.
generally set record locks on every index record that is scanned in the
processing of the SQL statement. It does not matter whether there are
`WHERE' conditions in the statement that would exclude the row.
`InnoDB' does not remember the exact `WHERE' condition, but only knows
which index ranges were scanned. The locks are normally next-key locks
that also block inserts into the `gap' immediately before the record.
However, gap locking can be disabled explicitly, which causes next-key
locking not to be used. For more information, see *Note
innodb-record-level-locks::.

Differences between shared and exclusive locks are described in *Note
innodb-lock-modes::.

If you have no indexes suitable for your statement and MySQL must scan
the entire table to process the statement, every row of the table
becomes locked, which in turn blocks all inserts by other users to the
table. It is important to create good indexes so that your queries do
not unnecessarily scan many rows.

For *Note `SELECT ... FOR UPDATE': select. or *Note `SELECT ... LOCK IN
SHARE MODE': select, locks are acquired for scanned rows, and expected
to be released for rows that do not qualify for inclusion in the result
set (for example, if they do not meet the criteria given in the `WHERE'
clause).  However, in some cases, rows might not be unlocked immediately
because the relationship between a result row and its original source
is lost during query execution. For example, in a *Note `UNION': union,
scanned (and locked) rows from a table might be inserted into a
temporary table before evaluation whether they qualify for the result
set. In this circumstance, the relationship of the rows in the temporary
table to the rows in the original table is lost and the latter rows are
not unlocked until the end of query execution.

`InnoDB' sets specific types of locks as follows. If a secondary index
is used in the search and index record locks to be set are exclusive,
`InnoDB' also retrieves the corresponding clustered index records and
sets locks on them.

   * *Note `SELECT ... FROM': select. is a consistent read, reading a
     snapshot of the database and setting no locks unless the
     transaction isolation level is set to `SERIALIZABLE'. For
     `SERIALIZABLE' level, the search sets shared next-key locks on the
     index records it encounters.

   * *Note `SELECT ... FROM ... LOCK IN SHARE MODE': select. sets
     shared next-key locks on all index records the search encounters.

   * *Note `SELECT ... FROM ... FOR UPDATE': select. sets exclusive
     next-key locks on all index records the search encounters.

   * *Note `UPDATE ... WHERE ...': update. sets an exclusive next-key
     lock on every record the search encounters.

   * *Note `DELETE FROM ... WHERE ...': delete. sets an exclusive
     next-key lock on every record the search encounters.

   * *Note `INSERT': insert. sets an exclusive lock on the inserted
     row. This lock is an index-record lock, not a next-key lock (that
     is, there is no gap lock) and does not prevent other sessions from
     inserting into the gap before the inserted row.

     Prior to inserting the row, a type of gap lock called an insertion
     intention gap lock is set. This lock signals the intent to insert
     in such a way that multiple transactions inserting into the same
     index gap need not wait for each other if they are not inserting
     at the same position within the gap. Suppose that there are index
     records with values of 4 and 7. Separate transactions that attempt
     to insert values of 5 and 6 each lock the gap between 4 and 7 with
     insert intention locks prior to obtaining the exclusive lock on the
     inserted row, but do not block each other because the rows are
     non-conflicting.

     If a duplicate-key error occurs, a shared lock on the duplicate
     index record is set. This use of a shared lock can result in
     deadlock should there be multiple sessions trying to insert the
     same row if another session already has an exclusive lock. This
     can occur if another session deletes the row. Suppose that an
     `InnoDB' table `t1' has the following structure:

          CREATE TABLE t1 (i INT, PRIMARY KEY (i)) ENGINE = InnoDB;

     Now suppose that three sessions perform the following operations
     in order:

     Session 1:

          START TRANSACTION;
          INSERT INTO t1 VALUES(1);

     Session 2:

          START TRANSACTION;
          INSERT INTO t1 VALUES(1);

     Session 3:

          START TRANSACTION;
          INSERT INTO t1 VALUES(1);

     Session 1:

          ROLLBACK;

     The first operation by session 1 acquires an exclusive lock for
     the row. The operations by sessions 2 and 3 both result in a
     duplicate-key error and they both request a shared lock for the
     row. When session 1 rolls back, it releases its exclusive lock on
     the row and the queued shared lock requests for sessions 2 and 3
     are granted. At this point, sessions 2 and 3 deadlock: Neither can
     acquire an exclusive lock for the row because of the shared lock
     held by the other.

     A similar situation occurs if the table already contains a row
     with key value 1 and three sessions perform the following
     operations in order:

     Session 1:

          START TRANSACTION;
          DELETE FROM t1 WHERE i = 1;

     Session 2:

          START TRANSACTION;
          INSERT INTO t1 VALUES(1);

     Session 3:

          START TRANSACTION;
          INSERT INTO t1 VALUES(1);

     Session 1:

          COMMIT;

     The first operation by session 1 acquires an exclusive lock for
     the row. The operations by sessions 2 and 3 both result in a
     duplicate-key error and they both request a shared lock for the
     row. When session 1 commits, it releases its exclusive lock on the
     row and the queued shared lock requests for sessions 2 and 3 are
     granted. At this point, sessions 2 and 3 deadlock: Neither can
     acquire an exclusive lock for the row because of the shared lock
     held by the other.

   * *Note `REPLACE': replace. is done like an *Note `INSERT': insert.
     if there is no collision on a unique key. Otherwise, an exclusive
     next-key lock is placed on the row that must be updated.

   * `INSERT INTO T SELECT ... FROM S WHERE ...' sets an exclusive
     index record without a gap lock on each row inserted into `T'. If
     `innodb_locks_unsafe_for_binlog' is enabled or the transaction
     isolation level is `READ COMMITTED', `InnoDB' does the search on
     `S' as a consistent read (no locks).  Otherwise, `InnoDB' sets
     shared next-key locks on rows from `S'.  `InnoDB' has to set locks
     in the latter case: In roll-forward recovery from a backup, every
     SQL statement must be executed in exactly the same way it was done
     originally.

   * `CREATE TABLE ... SELECT ...' performs the *Note `SELECT': select.
     with shared locks or as a consistent read, as in the previous
     `INSERT ...  SELECT' item.

   * While initializing a previously specified `AUTO_INCREMENT' column
     on a table, `InnoDB' sets an exclusive lock on the end of the
     index associated with the `AUTO_INCREMENT' column. In accessing the
     auto-increment counter, `InnoDB' uses a specific `AUTO-INC' table
     lock mode where the lock lasts only to the end of the current SQL
     statement, not to the end of the entire transaction. Other sessions
     cannot insert into the table while the `AUTO-INC' table lock is
     held; see *Note innodb-transaction-model::.

     `InnoDB' fetches the value of a previously initialized
     `AUTO_INCREMENT' column without setting any locks.

   * If a `FOREIGN KEY' constraint is defined on a table, any insert,
     update, or delete that requires the constraint condition to be
     checked sets shared record-level locks on the records that it
     looks at to check the constraint. `InnoDB' also sets these locks
     in the case where the constraint fails.

   * *Note `LOCK TABLES': lock-tables. sets table locks, but it is the
     higher MySQL layer above the `InnoDB' layer that sets these locks.
     `InnoDB' is aware of table locks if `innodb_table_locks = 1' (the
     default) and `autocommit = 0', and the MySQL layer above `InnoDB'
     knows about row-level locks.

     Otherwise, `InnoDB''s automatic deadlock detection cannot detect
     deadlocks where such table locks are involved. Also, because in
     this case the higher MySQL layer does not know about row-level
     locks, it is possible to get a table lock on a table where another
     session currently has row-level locks. However, this does not
     endanger transaction integrity, as discussed in *Note
     innodb-deadlock-detection::. See also *Note innodb-restrictions::.


File: manual.info,  Node: innodb-implicit-commit,  Next: innodb-deadlock-detection,  Prev: innodb-locks-set,  Up: innodb-transaction-model

13.7.8.7 Implicit Transaction Commit and Rollback
.................................................

By default, MySQL starts the session for each new connection with
autocommit mode enabled, so MySQL does a commit after each SQL
statement if that statement did not return an error. If a statement
returns an error, the commit or rollback behavior depends on the error.
See *Note innodb-error-handling::.

If a session that has autocommit disabled ends without explicitly
committing the final transaction, MySQL rolls back that transaction.

Some statements implicitly end a transaction, as if you had done a
*Note `COMMIT': commit. before executing the statement. For details,
see *Note implicit-commit::.


File: manual.info,  Node: innodb-deadlock-detection,  Next: innodb-deadlocks,  Prev: innodb-implicit-commit,  Up: innodb-transaction-model

13.7.8.8 Deadlock Detection and Rollback
........................................

`InnoDB' automatically detects transaction deadlocks and rolls back a
transaction or transactions to break the deadlock. `InnoDB' tries to
pick small transactions to roll back, where the size of a transaction is
determined by the number of rows inserted, updated, or deleted.

`InnoDB' is aware of table locks if `innodb_table_locks = 1' (the
default) and `autocommit = 0', and the MySQL layer above it knows about
row-level locks. Otherwise, `InnoDB' cannot detect deadlocks where a
table lock set by a MySQL *Note `LOCK TABLES': lock-tables.  statement
or a lock set by a storage engine other than `InnoDB' is involved. You
must resolve these situations by setting the value of the
`innodb_lock_wait_timeout' system variable.

When `InnoDB' performs a complete rollback of a transaction, all locks
set by the transaction are released.  However, if just a single SQL
statement is rolled back as a result of an error, some of the locks set
by the statement may be preserved. This happens because `InnoDB' stores
row locks in a format such that it cannot know afterward which lock was
set by which statement.

As of MySQL 6.0.5, if a *Note `SELECT': select.  calls a stored
function in a transaction, and a statement within the function fails,
that statement rolls back. Furthermore, if *Note `ROLLBACK': commit. is
executed after that, the entire transaction rolls back. Before 6.0.5,
the failed statement did not roll back when it failed (even though it
might ultimately get rolled back by a *Note `ROLLBACK': commit. later
that rolls back the entire transaction).


File: manual.info,  Node: innodb-deadlocks,  Prev: innodb-deadlock-detection,  Up: innodb-transaction-model

13.7.8.9 How to Cope with Deadlocks
...................................

Deadlocks are a classic problem in transactional databases, but they
are not dangerous unless they are so frequent that you cannot run
certain transactions at all. Normally, you must write your applications
so that they are always prepared to re-issue a transaction if it gets
rolled back because of a deadlock.

`InnoDB' uses automatic row-level locking. You can get deadlocks even
in the case of transactions that just insert or delete a single row.
That is because these operations are not really `atomic'; they
automatically set locks on the (possibly several) index records of the
row inserted or deleted.

You can cope with deadlocks and reduce the likelihood of their
occurrence with the following techniques:

   * Use *Note `SHOW ENGINE INNODB STATUS': show-engine. to determine
     the cause of the latest deadlock. That can help you to tune your
     application to avoid deadlocks.

   * Always be prepared to re-issue a transaction if it fails due to
     deadlock. Deadlocks are not dangerous. Just try again.

   * Commit your transactions often. Small transactions are less prone
     to collision.

   * If you are using locking reads (*Note `SELECT ... FOR UPDATE':
     select. or `SELECT ...  LOCK IN SHARE MODE'), try using a lower
     isolation level such as `READ COMMITTED'.

   * Access your tables and rows in a fixed order. Then transactions
     form well-defined queues and do not deadlock.

   * Add well-chosen indexes to your tables. Then your queries need to
     scan fewer index records and consequently set fewer locks. Use
     *Note `EXPLAIN SELECT': explain. to determine which indexes the
     MySQL server regards as the most appropriate for your queries.

   * Use less locking. If you can afford to allow a *Note `SELECT':
     select. to return data from an old snapshot, do not add the clause
     `FOR UPDATE' or `LOCK IN SHARE MODE' to it. Using the `READ
     COMMITTED' isolation level is good here, because each consistent
     read within the same transaction reads from its own fresh snapshot.

   * If nothing else helps, serialize your transactions with
     table-level locks. The correct way to use *Note `LOCK TABLES':
     lock-tables. with transactional tables, such as `InnoDB' tables,
     is to begin a transaction with `SET autocommit = 0' (not *Note
     `START TRANSACTION': commit.) followed by *Note `LOCK TABLES':
     lock-tables, and to not call *Note `UNLOCK TABLES': lock-tables.
     until you commit the transaction explicitly. For example, if you
     need to write to table `t1' and read from table `t2', you can do
     this:

          SET autocommit=0;
          LOCK TABLES t1 WRITE, t2 READ, ...;
          ... DO SOMETHING WITH TABLES T1 AND T2 HERE ...
          COMMIT;
          UNLOCK TABLES;

     Table-level locks make your transactions queue nicely and avoid
     deadlocks.

   * Another way to serialize transactions is to create an auxiliary
     `semaphore' table that contains just a single row. Have each
     transaction update that row before accessing other tables. In that
     way, all transactions happen in a serial fashion. Note that the
     `InnoDB' instant deadlock detection algorithm also works in this
     case, because the serializing lock is a row-level lock. With MySQL
     table-level locks, the timeout method must be used to resolve
     deadlocks.


File: manual.info,  Node: innodb-multi-versioning,  Next: innodb-table-and-index,  Prev: innodb-transaction-model,  Up: innodb

13.7.9 `InnoDB' Multi-Versioning
--------------------------------

Because `InnoDB' is a multi-versioned storage engine, it must keep
information about old versions of rows in the tablespace. This
information is stored in a data structure called a _rollback segment_
(after an analogous data structure in Oracle).

Internally, `InnoDB' adds three fields to each row stored in the
database. A 6-byte `DB_TRX_ID' field indicates the transaction
identifier for the last transaction that inserted or updated the row.
Also, a deletion is treated internally as an update where a special bit
in the row is set to mark it as deleted. Each row also contains a 7-byte
`DB_ROLL_PTR' field called the roll pointer. The roll pointer points to
an undo log record written to the rollback segment. If the row was
updated, the undo log record contains the information necessary to
rebuild the content of the row before it was updated. A 6-byte
`DB_ROW_ID' field contains a row ID that increases monotonically as new
rows are inserted. If `InnoDB' generates a clustered index
automatically, the index contains row ID values. Otherwise, the
`DB_ROW_ID' column does not appear in any index.

`InnoDB' uses the information in the rollback segment to perform the
undo operations needed in a transaction rollback. It also uses the
information to build earlier versions of a row for a consistent read.

Undo logs in the rollback segment are divided into insert and update
undo logs. Insert undo logs are needed only in transaction rollback and
can be discarded as soon as the transaction commits.  Update undo logs
are used also in consistent reads, but they can be discarded only after
there is no transaction present for which `InnoDB' has assigned a
snapshot that in a consistent read could need the information in the
update undo log to build an earlier version of a database row.

You must remember to commit your transactions regularly, including
those transactions that issue only consistent reads. Otherwise,
`InnoDB' cannot discard data from the update undo logs, and the
rollback segment may grow too big, filling up your tablespace.

The physical size of an undo log record in the rollback segment is
typically smaller than the corresponding inserted or updated row.  You
can use this information to calculate the space need for your rollback
segment.

In the `InnoDB' multi-versioning scheme, a row is not physically
removed from the database immediately when you delete it with an SQL
statement. Only when `InnoDB' can discard the update undo log record
written for the deletion can it also physically remove the
corresponding row and its index records from the database. This removal
operation is called a purge, and it is quite fast, usually taking the
same order of time as the SQL statement that did the deletion.

In a scenario where the user inserts and deletes rows in smallish
batches at about the same rate in the table, it is possible that the
purge thread starts to lag behind, and the table grows bigger and
bigger, making everything disk-bound and very slow. Even if the table
carries just 10MB of useful data, it may grow to occupy 10GB with all
the `dead' rows. In such a case, it would be good to throttle new row
operations and allocate more resources to the purge thread. The
`innodb_max_purge_lag' system variable exists for exactly this purpose.
See *Note innodb-parameters::, for more information.


File: manual.info,  Node: innodb-table-and-index,  Next: file-space-management,  Prev: innodb-multi-versioning,  Up: innodb

13.7.10 `InnoDB' Table and Index Structures
-------------------------------------------

* Menu:

* innodb-index-types::           Clustered and Secondary Indexes
* innodb-physical-structure::    Physical Structure of an Index
* innodb-insert-buffering::      Insert Buffering
* innodb-adaptive-hash::         Adaptive Hash Indexes
* innodb-physical-record::       Physical Row Structure

MySQL stores its data dictionary information for tables in `.frm' files
in database directories. This is true for all MySQL storage engines,
but every `InnoDB' table also has its own entry in the `InnoDB'
internal data dictionary inside the tablespace. When MySQL drops a
table or a database, it has to delete one or more `.frm' files as well
as the corresponding entries inside the `InnoDB' data dictionary.
Consequently, you cannot move `InnoDB' tables between databases simply
by moving the `.frm' files.


File: manual.info,  Node: innodb-index-types,  Next: innodb-physical-structure,  Prev: innodb-table-and-index,  Up: innodb-table-and-index

13.7.10.1 Clustered and Secondary Indexes
.........................................

Every `InnoDB' table has a special index called the _clustered index_
where the data for the rows is stored:

   * If you define a `PRIMARY KEY' on your table, `InnoDB' uses it as
     the clustered index.

   * If you do not define a `PRIMARY KEY' for your table, MySQL picks
     the first `UNIQUE' index that has only `NOT NULL' columns as the
     primary key and `InnoDB' uses it as the clustered index.

   * If the table has no `PRIMARY KEY' or suitable `UNIQUE' index,
     `InnoDB' internally generates a hidden clustered index on a
     synthetic column containing row ID values. The rows are ordered by
     the ID that `InnoDB' assigns to the rows in such a table. The row
     ID is a 6-byte field that increases monotonically as new rows are
     inserted. Thus, the rows ordered by the row ID are physically in
     insertion order.

Accessing a row through the clustered index is fast because the row
data is on the same page where the index search leads. If a table is
large, the clustered index architecture often saves a disk I/O
operation when compared to storage organizations that store row data
using a different page from the index record.  (For example, `MyISAM'
uses one file for data rows and another for index records.)

In `InnoDB', the records in non-clustered indexes (also called
secondary indexes) contain the primary key columns for the row that are
not in the secondary index.  `InnoDB' uses this primary key value to
search for the row in the clustered index. If the primary key is long,
the secondary indexes use more space, so it is advantageous to have a
short primary key.


File: manual.info,  Node: innodb-physical-structure,  Next: innodb-insert-buffering,  Prev: innodb-index-types,  Up: innodb-table-and-index

13.7.10.2 Physical Structure of an Index
........................................

All `InnoDB' indexes are B-trees where the index records are stored in
the leaf pages of the tree. The default size of an index page is 16KB.
When new records are inserted, `InnoDB' tries to leave 1/16 of the page
free for future insertions and updates of the index records.

If index records are inserted in a sequential order (ascending or
descending), the resulting index pages are about 15/16 full.  If
records are inserted in a random order, the pages are from 1/2 to 15/16
full. If the fill factor of an index page drops below 1/2, `InnoDB'
tries to contract the index tree to free the page.


File: manual.info,  Node: innodb-insert-buffering,  Next: innodb-adaptive-hash,  Prev: innodb-physical-structure,  Up: innodb-table-and-index

13.7.10.3 Insert Buffering
..........................

It is a common situation in database applications that the primary key
is a unique identifier and new rows are inserted in the ascending order
of the primary key. Thus, insertions into the clustered index do not
require random reads from a disk.

On the other hand, secondary indexes are usually non-unique, and
insertions into secondary indexes happen in a relatively random order.
This would cause a lot of random disk I/O operations without a special
mechanism used in `InnoDB'.

If an index record should be inserted into a non-unique secondary
index, `InnoDB' checks whether the secondary index page is in the
buffer pool. If that is the case, `InnoDB' does the insertion directly
to the index page. If the index page is not found in the buffer pool,
`InnoDB' inserts the record to a special insert buffer structure. The
insert buffer is kept so small that it fits entirely in the buffer
pool, and insertions can be done very fast.

Periodically, the insert buffer is merged into the secondary index
trees in the database. Often it is possible to merge several insertions
into the same page of the index tree, saving disk I/O operations. It
has been measured that the insert buffer can speed up insertions into a
table up to 15 times.

The insert buffer merging may continue to happen _after_ the inserting
transaction has been committed. In fact, it may continue to happen
after a server shutdown and restart (see *Note forcing-recovery::).

Insert buffer merging may take many hours when many secondary indexes
must be updated and many rows have been inserted. During this time,
disk I/O will be increased, which can cause significant slowdown on
disk-bound queries. Another significant background I/O operation is the
purge thread (see *Note innodb-multi-versioning::).


File: manual.info,  Node: innodb-adaptive-hash,  Next: innodb-physical-record,  Prev: innodb-insert-buffering,  Up: innodb-table-and-index

13.7.10.4 Adaptive Hash Indexes
...............................

If a table fits almost entirely in main memory, the fastest way to
perform queries on it is to use hash indexes.  `InnoDB' has a mechanism
that monitors index searches made to the indexes defined for a table. If
`InnoDB' notices that queries could benefit from building a hash index,
it does so automatically.

The hash index is always built based on an existing B-tree index on the
table. `InnoDB' can build a hash index on a prefix of any length of the
key defined for the B-tree, depending on the pattern of searches that
`InnoDB' observes for the B-tree index. A hash index can be partial: It
is not required that the whole B-tree index is cached in the buffer
pool. `InnoDB' builds hash indexes on demand for those pages of the
index that are often accessed.

In a sense, `InnoDB' tailors itself through the adaptive hash index
mechanism to ample main memory, coming closer to the architecture of
main-memory databases.


File: manual.info,  Node: innodb-physical-record,  Prev: innodb-adaptive-hash,  Up: innodb-table-and-index

13.7.10.5 Physical Row Structure
................................

The physical row structure for an `InnoDB' table depends on the row
format specified when the table was created. `InnoDB' uses the
`COMPACT' format by default, but the `REDUNDANT' format is available to
retain compatibility with older versions of MySQL. To check the row
format of an `InnoDB' table, use *Note `SHOW TABLE STATUS':
show-table-status.

The compact row format decreases row storage space by about 20% at the
cost of increasing CPU use for some operations. If your workload is a
typical one that is limited by cache hit rates and disk speed, compact
format is likely to be faster. If the workload is a rare case that is
limited by CPU speed, compact format might be slower.

Rows in `InnoDB' tables that use `REDUNDANT' row format have the
following characteristics:

   * Each index record contains a six-byte header. The header is used
     to link together consecutive records, and also in row-level
     locking.

   * Records in the clustered index contain fields for all user-defined
     columns. In addition, there is a six-byte transaction ID field and
     a seven-byte roll pointer field.

   * If no primary key was defined for a table, each clustered index
     record also contains a six-byte row ID field.

   * Each secondary index record also contains all the primary key
     fields defined for the clustered index key that are not in the
     secondary index.

   * A record contains a pointer to each field of the record. If the
     total length of the fields in a record is less than 128 bytes, the
     pointer is one byte; otherwise, two bytes. The array of these
     pointers is called the record directory. The area where these
     pointers point is called the data part of the record.

   * Internally, `InnoDB' stores fixed-length character columns such as
     *Note `CHAR(10)': char. in a fixed-length format. `InnoDB' does
     not truncate trailing spaces from *Note `VARCHAR': char. columns.

   * An SQL `NULL' value reserves one or two bytes in the record
     directory. Besides that, an SQL `NULL' value reserves zero bytes
     in the data part of the record if stored in a variable length
     column. In a fixed-length column, it reserves the fixed length of
     the column in the data part of the record.  Reserving the fixed
     space for `NULL' values enables an update of the column from `NULL'
     to a non-`NULL' value to be done in place without causing
     fragmentation of the index page.

Rows in `InnoDB' tables that use `COMPACT' row format have the following
characteristics:

   * Each index record contains a five-byte header that may be preceded
     by a variable-length header. The header is used to link together
     consecutive records, and also in row-level locking.

   * The variable-length part of the record header contains a bit
     vector for indicating `NULL' columns. If the number of columns in
     the index that can be `NULL' is N, the bit vector occupies (N+7)/8
     bytes. Columns that are `NULL' do not occupy space other than the
     bit in this vector. The variable-length part of the header also
     contains the lengths of variable-length columns. Each length takes
     one or two bytes, depending on the maximum length of the column.
     If all columns in the index are `NOT NULL' and have a fixed
     length, the record header has no variable-length part.

   * For each non-`NULL' variable-length field, the record header
     contains the length of the column in one or two bytes. Two bytes
     will only be needed if part of the column is stored externally in
     overflow pages or the maximum length exceeds 255 bytes and the
     actual length exceeds 127 bytes. For an externally stored column,
     the two-byte length indicates the length of the internally stored
     part plus the 20-byte pointer to the externally stored part. The
     internal part is 768 bytes, so the length is 768+20. The 20-byte
     pointer stores the true length of the column.

   * The record header is followed by the data contents of the
     non-`NULL' columns.

   * Records in the clustered index contain fields for all user-defined
     columns. In addition, there is a six-byte transaction ID field and
     a seven-byte roll pointer field.

   * If no primary key was defined for a table, each clustered index
     record also contains a six-byte row ID field.

   * Each secondary index record also contains all the primary key
     fields defined for the clustered index key that are not in the
     secondary index. If any of these primary key fields are variable
     length, the record header for each secondary index will have a
     variable-length part to record their lengths, even if the
     secondary index is defined on fixed-length columns.

   * Internally, `InnoDB' stores fixed-length, fixed-width character
     columns such as *Note `CHAR(10)': char. in a fixed-length format.
     `InnoDB' does not truncate trailing spaces from *Note `VARCHAR':
     char. columns.

   * Internally, `InnoDB' attempts to store UTF-8 *Note `CHAR(N)': char.
     columns in N bytes by trimming trailing spaces. (With `REDUNDANT'
     row format, such columns occupy 4 x N bytes.) Reserving the minimum
     space N in many cases enables column updates to be done in place
     without causing fragmentation of the index page.


File: manual.info,  Node: file-space-management,  Next: innodb-error-handling,  Prev: innodb-table-and-index,  Up: innodb

13.7.11 `InnoDB' Disk I/O and File Space Management
---------------------------------------------------

* Menu:

* innodb-disk-io::               `InnoDB' Disk I/O
* innodb-file-space::            File Space Management
* innodb-file-defragmenting::    Defragmenting a Table


File: manual.info,  Node: innodb-disk-io,  Next: innodb-file-space,  Prev: file-space-management,  Up: file-space-management

13.7.11.1 `InnoDB' Disk I/O
...........................

`InnoDB' uses simulated asynchronous disk I/O: `InnoDB' creates a
number of threads to take care of I/O operations, such as read-ahead.

There are two read-ahead heuristics in `InnoDB':

   * In sequential read-ahead, if `InnoDB' notices that the access
     pattern to a segment in the tablespace is sequential, it posts in
     advance a batch of reads of database pages to the I/O system.

   * In random read-ahead, if `InnoDB' notices that some area in a
     tablespace seems to be in the process of being fully read into the
     buffer pool, it posts the remaining reads to the I/O system.

`InnoDB' uses a novel file flush technique called _doublewrite_. It
adds safety to recovery following an operating system crash or a power
outage, and improves performance on most varieties of Unix by reducing
the need for `fsync()' operations.

Doublewrite means that before writing pages to a data file, `InnoDB'
first writes them to a contiguous tablespace area called the
doublewrite buffer. Only after the write and the flush to the
doublewrite buffer has completed does `InnoDB' write the pages to their
proper positions in the data file. If the operating system crashes in
the middle of a page write, `InnoDB' can later find a good copy of the
page from the doublewrite buffer during recovery.


File: manual.info,  Node: innodb-file-space,  Next: innodb-file-defragmenting,  Prev: innodb-disk-io,  Up: file-space-management

13.7.11.2 File Space Management
...............................

The data files that you define in the configuration file form the
`InnoDB' tablespace. The files are simply concatenated to form the
tablespace. There is no striping in use. Currently, you cannot define
where within the tablespace your tables are allocated. However, in a
newly created tablespace, `InnoDB' allocates space starting from the
first data file.

The tablespace consists of database pages with a default size of 16KB.
The pages are grouped into extents of size 1MB (64 consecutive pages).
The `files' inside a tablespace are called _segments_ in `InnoDB'. The
term `rollback segment' is somewhat confusing because it actually
contains many tablespace segments.

When a segment grows inside the tablespace, `InnoDB' allocates the
first 32 pages to it individually. After that, `InnoDB' starts to
allocate whole extents to the segment. `InnoDB' can add up to 4 extents
at a time to a large segment to ensure good sequentiality of data.

Two segments are allocated for each index in `InnoDB'. One is for
non-leaf nodes of the B-tree, the other is for the leaf nodes. The idea
here is to achieve better sequentiality for the leaf nodes, which
contain the data.

Some pages in the tablespace contain bitmaps of other pages, and
therefore a few extents in an `InnoDB' tablespace cannot be allocated
to segments as a whole, but only as individual pages.

When you ask for available free space in the tablespace by issuing a
*Note `SHOW TABLE STATUS': show-table-status.  statement, `InnoDB'
reports the extents that are definitely free in the tablespace. `InnoDB'
always reserves some extents for cleanup and other internal purposes;
these reserved extents are not included in the free space.

When you delete data from a table, `InnoDB' contracts the corresponding
B-tree indexes. Whether the freed space becomes available for other
users depends on whether the pattern of deletes frees individual pages
or extents to the tablespace. Dropping a table or deleting all rows
from it is guaranteed to release the space to other users, but remember
that deleted rows are physically removed only in an (automatic) purge
operation after they are no longer needed for transaction rollbacks or
consistent reads. (See *Note innodb-multi-versioning::.)

The maximum row length, except for variable-length columns (*Note
`VARBINARY': binary-varbinary, *Note `VARCHAR': char, *Note `BLOB':
blob. and *Note `TEXT': blob.), is slightly less than half of a
database page. That is, the maximum row length is about 8000 bytes.
*Note `LONGBLOB': blob. and *Note `LONGTEXT': blob. columns must be less
than 4GB, and the total row length, including *Note `BLOB': blob. and
*Note `TEXT': blob. columns, must be less than 4GB.

If a row is less than half a page long, all of it is stored locally
within the page. If it exceeds half a page, variable-length columns are
chosen for external off-page storage until the row fits within half a
page. For a column chosen for off-page storage, `InnoDB' stores the
first 768 bytes locally in the row, and the rest externally into
overflow pages. Each such column has its own list of overflow pages. The
768-byte prefix is accompanied by a 20-byte value that stores the true
length of the column and points into the overflow list where the rest
of the value is stored.

To see information about the tablespace, use the Tablespace Monitor.
See *Note innodb-monitors::.


File: manual.info,  Node: innodb-file-defragmenting,  Prev: innodb-file-space,  Up: file-space-management

13.7.11.3 Defragmenting a Table
...............................

If there are random insertions into or deletions from the indexes of a
table, the indexes may become fragmented.  Fragmentation means that the
physical ordering of the index pages on the disk is not close to the
index ordering of the records on the pages, or that there are many
unused pages in the 64-page blocks that were allocated to the index.

One symptom of fragmentation is that a table takes more space than it
`should' take. How much that is exactly, is difficult to determine. All
`InnoDB' data and indexes are stored in B-trees, and their fill factor
may vary from 50% to 100%. Another symptom of fragmentation is that a
table scan such as this takes more time than it `should' take:

     SELECT COUNT(*) FROM t WHERE a_non_indexed_column <> 12345;

(In the preceding query, we are `fooling' the SQL optimizer into
scanning the clustered index rather than a secondary index.) Most disks
can read 10MB/s to 50MB/s, which can be used to estimate how fast a
table scan should be.

It can speed up index scans if you periodically perform a `null' *Note
`ALTER TABLE': alter-table.  operation, which causes MySQL to rebuild
the table:

     ALTER TABLE TBL_NAME ENGINE=INNODB

Another way to perform a defragmentation operation is to use *Note
`mysqldump': mysqldump. to dump the table to a text file, drop the
table, and reload it from the dump file.

If the insertions into an index are always ascending and records are
deleted only from the end, the `InnoDB' filespace management algorithm
guarantees that fragmentation in the index does not occur.


File: manual.info,  Node: innodb-error-handling,  Next: innodb-tuning-troubleshooting,  Prev: file-space-management,  Up: innodb

13.7.12 `InnoDB' Error Handling
-------------------------------

* Menu:

* innodb-error-codes::           `InnoDB' Error Codes
* operating-system-error-codes::  Operating System Error Codes

Error handling in `InnoDB' is not always the same as specified in the
SQL standard. According to the standard, any error during an SQL
statement should cause rollback of that statement. `InnoDB' sometimes
rolls back only part of the statement, or the whole transaction. The
following items describe how `InnoDB' performs error handling:

   * If you run out of file space in the tablespace, a MySQL `Table is
     full' error occurs and `InnoDB' rolls back the SQL statement.

   * A transaction deadlock causes `InnoDB' to roll back the entire
     transaction. You should normally retry the whole transaction when
     this happens.

     A lock wait timeout causes `InnoDB' to roll back only the single
     statement that was waiting for the lock and encountered the
     timeout. (To have the entire transaction roll back, start the
     server with the `--innodb_rollback_on_timeout' option.) You should
     normally retry the statement if using the current behavior or the
     entire transaction if using `--innodb_rollback_on_timeout'.

     Both deadlocks and lock wait timeouts are normal on busy servers
     and it is necessary for applications to be aware that they may
     happen and handle them by retrying. You can make them less likely
     by doing as little work as possible between the first change to
     data during a transaction and the commit, so the locks are held
     for the shortest possible time and for the smallest possible
     number of rows. Sometimes splitting work between different
     transactions may be practical and helpful.

     When a transaction rollback occurs due to a deadlock or lock wait
     timeout, it cancels the effect of the statements within the
     transaction. But if the start-transaction statement was *Note
     `START TRANSACTION': commit. or *Note `BEGIN': commit.  statement,
     rollback does not cancel that statement. Further SQL statements
     become part of the transaction until the occurrence of *Note
     `COMMIT': commit, *Note `ROLLBACK': commit, or some SQL statement
     that causes an implicit commit.

   * A duplicate-key error rolls back the SQL statement, if you have
     not specified the `IGNORE' option in your statement.

   * A `row too long error' rolls back the SQL statement.

   * Other errors are mostly detected by the MySQL layer of code (above
     the `InnoDB' storage engine level), and they roll back the
     corresponding SQL statement. Locks are not released in a rollback
     of a single SQL statement.

During implicit rollbacks, as well as during the execution of an
explicit *Note `ROLLBACK': commit. SQL statement, *Note `SHOW
PROCESSLIST': show-processlist.  displays `Rolling back' in the `State'
column for the relevant connection.


File: manual.info,  Node: innodb-error-codes,  Next: operating-system-error-codes,  Prev: innodb-error-handling,  Up: innodb-error-handling

13.7.12.1 `InnoDB' Error Codes
..............................

The following is a non-exhaustive list of common `InnoDB'-specific
errors that you may encounter, with information about why each occurs
and how to resolve the problem.

   * `1005 (ER_CANT_CREATE_TABLE)'

     Cannot create table. If the error message refers to error 150,
     table creation failed because a foreign key constraint was not
     correctly formed. If the error message refers to error -1, table
     creation probably failed because the table includes a column name
     that matched the name of an internal `InnoDB' table.

   * `1016 (ER_CANT_OPEN_FILE)'

     Cannot find the `InnoDB' table from the `InnoDB' data files,
     although the `.frm' file for the table exists. See *Note
     innodb-troubleshooting-datadict::.

   * `1114 (ER_RECORD_FILE_FULL)'

     `InnoDB' has run out of free space in the tablespace. You should
     reconfigure the tablespace to add a new data file.

   * `1205 (ER_LOCK_WAIT_TIMEOUT)'

     Lock wait timeout expired. Transaction was rolled back.

   * `1213 (ER_LOCK_DEADLOCK)'

     Transaction deadlock. You should rerun the transaction.

   * `1216 (ER_NO_REFERENCED_ROW)'

     You are trying to add a row but there is no parent row, and a
     foreign key constraint fails. You should add the parent row first.

   * `1217 (ER_ROW_IS_REFERENCED)'

     You are trying to delete a parent row that has children, and a
     foreign key constraint fails. You should delete the children first.


File: manual.info,  Node: operating-system-error-codes,  Prev: innodb-error-codes,  Up: innodb-error-handling

13.7.12.2 Operating System Error Codes
......................................

To print the meaning of an operating system error number, use the *Note
`perror': perror. program that comes with the MySQL distribution.

The following table provides a list of some common Linux system error
codes. For a more complete list, see Linux source code
(http://www.iglu.org.il/lxr/source/include/asm-i386/errno.h).

   * `1 (EPERM)'

     Operation not permitted

   * `2 (ENOENT)'

     No such file or directory

   * `3 (ESRCH)'

     No such process

   * `4 (EINTR)'

     Interrupted system call

   * `5 (EIO)'

     I/O error

   * `6 (ENXIO)'

     No such device or address

   * `7 (E2BIG)'

     Arg list too long

   * `8 (ENOEXEC)'

     Exec format error

   * `9 (EBADF)'

     Bad file number

   * `10 (ECHILD)'

     No child processes

   * `11 (EAGAIN)'

     Try again

   * `12 (ENOMEM)'

     Out of memory

   * `13 (EACCES)'

     Permission denied

   * `14 (EFAULT)'

     Bad address

   * `15 (ENOTBLK)'

     Block device required

   * `16 (EBUSY)'

     Device or resource busy

   * `17 (EEXIST)'

     File exists

   * `18 (EXDEV)'

     Cross-device link

   * `19 (ENODEV)'

     No such device

   * `20 (ENOTDIR)'

     Not a directory

   * `21 (EISDIR)'

     Is a directory

   * `22 (EINVAL)'

     Invalid argument

   * `23 (ENFILE)'

     File table overflow

   * `24 (EMFILE)'

     Too many open files

   * `25 (ENOTTY)'

     Inappropriate ioctl for device

   * `26 (ETXTBSY)'

     Text file busy

   * `27 (EFBIG)'

     File too large

   * `28 (ENOSPC)'

     No space left on device

   * `29 (ESPIPE)'

     Illegal seek

   * `30 (EROFS)'

     Read-only file system

   * `31 (EMLINK)'

     Too many links

The following table provides a list of some common Windows system error
codes. For a complete list, see the Microsoft Web site
(http://msdn.microsoft.com/en-us/library/ms681381.aspx).

   * `1 (ERROR_INVALID_FUNCTION)'

     Incorrect function.

   * `2 (ERROR_FILE_NOT_FOUND)'

     The system cannot find the file specified.

   * `3 (ERROR_PATH_NOT_FOUND)'

     The system cannot find the path specified.

   * `4 (ERROR_TOO_MANY_OPEN_FILES)'

     The system cannot open the file.

   * `5 (ERROR_ACCESS_DENIED)'

     Access is denied.

   * `6 (ERROR_INVALID_HANDLE)'

     The handle is invalid.

   * `7 (ERROR_ARENA_TRASHED)'

     The storage control blocks were destroyed.

   * `8 (ERROR_NOT_ENOUGH_MEMORY)'

     Not enough storage is available to process this command.

   * `9 (ERROR_INVALID_BLOCK)'

     The storage control block address is invalid.

   * `10 (ERROR_BAD_ENVIRONMENT)'

     The environment is incorrect.

   * `11 (ERROR_BAD_FORMAT)'

     An attempt was made to load a program with an incorrect format.

   * `12 (ERROR_INVALID_ACCESS)'

     The access code is invalid.

   * `13 (ERROR_INVALID_DATA)'

     The data is invalid.

   * `14 (ERROR_OUTOFMEMORY)'

     Not enough storage is available to complete this operation.

   * `15 (ERROR_INVALID_DRIVE)'

     The system cannot find the drive specified.

   * `16 (ERROR_CURRENT_DIRECTORY)'

     The directory cannot be removed.

   * `17 (ERROR_NOT_SAME_DEVICE)'

     The system cannot move the file to a different disk drive.

   * `18 (ERROR_NO_MORE_FILES)'

     There are no more files.

   * `19 (ERROR_WRITE_PROTECT)'

     The media is write protected.

   * `20 (ERROR_BAD_UNIT)'

     The system cannot find the device specified.

   * `21 (ERROR_NOT_READY)'

     The device is not ready.

   * `22 (ERROR_BAD_COMMAND)'

     The device does not recognize the command.

   * `23 (ERROR_CRC)'

     Data error (cyclic redundancy check).

   * `24 (ERROR_BAD_LENGTH)'

     The program issued a command but the command length is incorrect.

   * `25 (ERROR_SEEK)'

     The drive cannot locate a specific area or track on the disk.

   * `26 (ERROR_NOT_DOS_DISK)'

     The specified disk or diskette cannot be accessed.

   * `27 (ERROR_SECTOR_NOT_FOUND)'

     The drive cannot find the sector requested.

   * `28 (ERROR_OUT_OF_PAPER)'

     The printer is out of paper.

   * `29 (ERROR_WRITE_FAULT)'

     The system cannot write to the specified device.

   * `30 (ERROR_READ_FAULT)'

     The system cannot read from the specified device.

   * `31 (ERROR_GEN_FAILURE)'

     A device attached to the system is not functioning.

   * `32 (ERROR_SHARING_VIOLATION)'

     The process cannot access the file because it is being used by
     another process.

   * `33 (ERROR_LOCK_VIOLATION)'

     The process cannot access the file because another process has
     locked a portion of the file.

   * `34 (ERROR_WRONG_DISK)'

     The wrong diskette is in the drive. Insert %2 (Volume Serial
     Number: %3) into drive %1.

   * `36 (ERROR_SHARING_BUFFER_EXCEEDED)'

     Too many files opened for sharing.

   * `38 (ERROR_HANDLE_EOF)'

     Reached the end of the file.

   * `39 (ERROR_HANDLE_DISK_FULL)'

     The disk is full.

   * `87 (ERROR_INVALID_PARAMETER)'

     The parameter is incorrect.

   * `112 (ERROR_DISK_FULL)'

     The disk is full.

   * `123 (ERROR_INVALID_NAME)'

     The file name, directory name, or volume label syntax is incorrect.

   * `1450 (ERROR_NO_SYSTEM_RESOURCES)'

     Insufficient system resources exist to complete the requested
     service.


File: manual.info,  Node: innodb-tuning-troubleshooting,  Next: innodb-restrictions,  Prev: innodb-error-handling,  Up: innodb

13.7.13 `InnoDB' Performance Tuning and Troubleshooting
-------------------------------------------------------

* Menu:

* innodb-tuning::                `InnoDB' Performance Tuning Tips
* innodb-monitors::              `SHOW ENGINE INNODB STATUS' and the `InnoDB' Monitors
* innodb-troubleshooting::       `InnoDB' General Troubleshooting
* innodb-troubleshooting-datadict::  Troubleshooting `InnoDB' Data Dictionary Operations


File: manual.info,  Node: innodb-tuning,  Next: innodb-monitors,  Prev: innodb-tuning-troubleshooting,  Up: innodb-tuning-troubleshooting

13.7.13.1 `InnoDB' Performance Tuning Tips
..........................................

   * In `InnoDB', having a long `PRIMARY KEY' wastes a lot of disk
     space because its value must be stored with every secondary index
     record. (See *Note innodb-table-and-index::.) Create an
     `AUTO_INCREMENT' column as the primary key if your primary key is
     long.

   * If you have `UNIQUE' constraints on secondary keys, you can speed
     up table imports by temporarily turning off the uniqueness checks
     during the import session:

          SET unique_checks=0;
          ... IMPORT OPERATION ...
          SET unique_checks=1;

     For big tables, this saves a lot of disk I/O because `InnoDB' can
     use its insert buffer to write secondary index records in a batch.
     Be certain that the data contains no duplicate keys.

   * If you have `FOREIGN KEY' constraints in your tables, you can
     speed up table imports by turning the foreign key checks off for
     the duration of the import session:

          SET foreign_key_checks=0;
          ... IMPORT OPERATION ...
          SET foreign_key_checks=1;

     For big tables, this can save a lot of disk I/O.

   * If the Unix `top' tool or the Windows Task Manager shows that the
     CPU usage percentage with your workload is less than 70%, your
     workload is probably disk-bound. Maybe you are making too many
     transaction commits, or the buffer pool is too small. Making the
     buffer pool bigger can help, but do not set it equal to more than
     80% of physical memory.

   * Wrap several modifications into a single transaction to reduce the
     number of flush operations.  `InnoDB' must flush the log to disk
     at each transaction commit if that transaction made modifications
     to the database. The rotation speed of a disk is typically at most
     167 revolutions/second, which constrains the number of commits to
     the same 167^th of a second if the disk does not `fool' the
     operating system.

   * If you can afford the loss of some of the latest committed
     transactions if a crash occurs, you can set the
     `innodb_flush_log_at_trx_commit' parameter to 0. `InnoDB' tries to
     flush the log once per second anyway, although the flush is not
     guaranteed. You should also set the value of `innodb_support_xa'
     to 0, which will reduce the number of disk flushes due to
     synchronizing on disk data and the binary log.

   * Make your log files big, even as big as the buffer pool.  When
     `InnoDB' has written the log files full, it must write the
     modified contents of the buffer pool to disk in a checkpoint.
     Small log files cause many unnecessary disk writes. The
     disadvantage of big log files is that the recovery time is longer.

   * Make the log buffer quite large as well (on the order of 8MB).

   * Use the *Note `VARCHAR': char. data type instead of *Note `CHAR':
     char. if you are storing variable-length strings or if the column
     may contain many `NULL' values. A *Note `CHAR(N)': char.  column
     always takes N characters to store data, even if the string is
     shorter or its value is `NULL'. Smaller tables fit better in the
     buffer pool and reduce disk I/O.

     When using `COMPACT' row format (the default `InnoDB' format in
     MySQL 6.0) and variable-length character sets, such as `utf8' or
     `sjis', *Note `CHAR(N)': char.  will occupy a variable amount of
     space, at least N bytes.

   * In some versions of GNU/Linux and Unix, flushing files to disk
     with the Unix `fsync()' call (which `InnoDB' uses by default) and
     other similar methods is surprisingly slow. If you are
     dissatisfied with database write performance, you might try
     setting the `innodb_flush_method' parameter to `O_DSYNC'. The
     `O_DSYNC' flush method seems to perform slower on most systems,
     but yours might not be one of them.

   * When using the `InnoDB' storage engine on Solaris 10 for x86_64
     architecture (AMD Opteron), it is important to mount any file
     systems used for storing `InnoDB'-related files using the
     `forcedirectio' option. (The default on Solaris 10/x86_64 is _not_
     to use this option.) Failure to use `forcedirectio' causes a
     serious degradation of `InnoDB''s speed and performance on this
     platform.

     When using the `InnoDB' storage engine with a large
     `innodb_buffer_pool_size' value on any release of Solaris 2.6 and
     up and any platform (sparc/x86/x64/amd64), a significant
     performance gain might be achieved by placing `InnoDB' data files
     and log files on raw devices or on a separate direct I/O UFS file
     system (using the `forcedirectio' mount option; see
     `mount_ufs(1M)'). Users of the Veritas file system VxFS should use
     the `convosync=direct' mount option. You are advised to perform
     tests with and without raw partitions or direct I/O file systems
     to verify whether performance is improved on your system.

     Other MySQL data files, such as those for `MyISAM' tables, should
     not be placed on a direct I/O file system. Executables or libraries
     _must not_ be placed on a direct I/O file system.

   * When importing data into `InnoDB', make sure that MySQL does not
     have autocommit mode enabled because that requires a log flush to
     disk for every insert.  To disable autocommit during your import
     operation, surround it with *Note `SET autocommit': commit. and
     *Note `COMMIT': commit. statements:

          SET autocommit=0;
          ... SQL IMPORT STATEMENTS ...
          COMMIT;

     If you use the *Note `mysqldump': mysqldump. option `--opt', you
     get dump files that are fast to import into an `InnoDB' table,
     even without wrapping them with the *Note `SET autocommit':
     commit. and *Note `COMMIT': commit. statements.

   * Beware of big rollbacks of mass inserts: `InnoDB' uses the insert
     buffer to save disk I/O in inserts, but no such mechanism is used
     in a corresponding rollback. A disk-bound rollback can take 30
     times as long to perform as the corresponding insert.  Killing the
     database process does not help because the rollback starts again
     on server startup. The only way to get rid of a runaway rollback
     is to increase the buffer pool so that the rollback becomes
     CPU-bound and runs fast, or to use a special procedure. See *Note
     forcing-recovery::.

   * Beware also of other big disk-bound operations. Use *Note `DROP
     TABLE': drop-table. and *Note `CREATE TABLE': create-table. to
     empty a table, not `DELETE FROM TBL_NAME'.

   * Use the multiple-row *Note `INSERT': insert.  syntax to reduce
     communication overhead between the client and the server if you
     need to insert many rows:

          INSERT INTO yourtable VALUES (1,2), (5,5), ...;

     This tip is valid for inserts into any table, not just `InnoDB'
     tables.

   * If you often have recurring queries for tables that are not
     updated frequently, enable the query cache:

          [mysqld]
          query_cache_type = 1
          query_cache_size = 10M

   * Unlike `MyISAM', `InnoDB' does not store an index cardinality
     value in its tables.  Instead, `InnoDB' computes a cardinality for
     a table the first time it accesses it after startup.  With a large
     number of tables, this might take significant time. It is the
     initial table open operation that is important, so to `warm up' a
     table for later use, access it immediately after startup by
     issuing a statement such as `SELECT 1 FROM TBL_NAME LIMIT 1'.

MySQL Enterprise

For optimization recommendations geared to your specific circumstances
subscribe to the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: innodb-monitors,  Next: innodb-troubleshooting,  Prev: innodb-tuning,  Up: innodb-tuning-troubleshooting

13.7.13.2 `SHOW ENGINE INNODB STATUS' and the `InnoDB' Monitors
...............................................................

* Menu:

* innodb-general-monitor::       `InnoDB' Standard and Lock Monitor Output
* innodb-tablespace-monitor::    `InnoDB' Tablespace Monitor Output
* innodb-table-monitor::         `InnoDB' Table Monitor Output

`InnoDB' Monitors provide information about the `InnoDB' internal
state. This information is useful for performance tuning. Each Monitor
can be enabled by creating a table with a special name, which causes
`InnoDB' to write Monitor output periodically.  Also, output for the
standard `InnoDB' Monitor is available on demand via the *Note `SHOW
ENGINE INNODB STATUS': show-engine. SQL statement.

There are several types of `InnoDB' Monitors:

   * The standard `InnoDB' Monitor displays the following types of
     information:

        * Table and record locks held by each active transaction

        * Lock waits of a transactions

        * Semaphore waits of threads

        * Pending file I/O requests

        * Buffer pool statistics

        * Purge and insert buffer merge activity of the main `InnoDB'
          thread

     For a discussion of `InnoDB' lock modes, see *Note
     innodb-lock-modes::.

     To enable the standard `InnoDB' Monitor for periodic output,
     create a table named `innodb_monitor'. To obtain Monitor output on
     demand, use the *Note `SHOW ENGINE INNODB STATUS': show-engine.
     SQL statement to fetch the output to your client program. If you
     are using the *Note `mysql': mysql. interactive client, the output
     is more readable if you replace the usual semicolon statement
     terminator with `\G':

          mysql> SHOW ENGINE INNODB STATUS\G

   * The `InnoDB' Lock Monitor is like the standard Monitor but also
     provides extensive lock information. To enable this Monitor for
     periodic output, create a table named `innodb_lock_monitor'.

   * The `InnoDB' Tablespace Monitor prints a list of file segments in
     the shared tablespace and validates the tablespace allocation data
     structures. To enable this Monitor for periodic output, create a
     table named `innodb_tablespace_monitor'.

   * The `InnoDB' Table Monitor prints the contents of the `InnoDB'
     internal data dictionary. To enable this Monitor for periodic
     output, create a table named `innodb_table_monitor'.

To enable an `InnoDB' Monitor for periodic output, use a `CREATE TABLE'
statement to create the table associated with the Monitor. For example,
to enable the standard `InnoDB' Monitor, create the `innodb_monitor'
table:

     CREATE TABLE innodb_monitor (a INT) ENGINE=INNODB;

To stop the Monitor, drop the table:

     DROP TABLE innodb_monitor;

The *Note `CREATE TABLE': create-table. syntax is just a way to pass a
command to the `InnoDB' engine through MySQL's SQL parser: The only
things that matter are the table name `innodb_monitor' and that it be an
`InnoDB' table. The structure of the table is not relevant at all for
the `InnoDB' Monitor.  If you shut down the server, the Monitor does
not restart automatically when you restart the server. You must drop the
Monitor table and issue a new *Note `CREATE TABLE': create-table.
statement to start the Monitor. (This syntax may change in a future
release.)

As of MySQL 6.0.5, the `PROCESS' privilege is required to start or stop
the `InnoDB' Monitor tables.

When you enable `InnoDB' Monitors for periodic output, `InnoDB' writes
their output to the *Note `mysqld': mysqld. server standard error output
(`stderr'). In this case, no output is sent to clients. When switched
on, `InnoDB' Monitors print data about every 15 seconds. Server output
usually is directed to the error log (see *Note error-log::).  This
data is useful in performance tuning. On Windows, you must start the
server from a command prompt in a console window with the `--console'
option if you want to direct the output to the window rather than to
the error log.

`InnoDB' sends diagnostic output to `stderr' or to files rather than to
`stdout' or fixed-size memory buffers, to avoid potential buffer
overflows. As a side effect, the output of *Note `SHOW ENGINE INNODB
STATUS': show-engine. is written to a status file in the MySQL data
directory every fifteen seconds. The name of the file is
`innodb_status.PID', where PID is the server process ID.  `InnoDB'
removes the file for a normal shutdown. If abnormal shutdowns have
occurred, instances of these status files may be present and must be
removed manually.  Before removing them, you might want to examine them
to see whether they contain useful information about the cause of
abnormal shutdowns. The `innodb_status.PID' file is created only if the
configuration option `innodb_status_file=1' is set.

`InnoDB' Monitors should be enabled only when you actually want to see
Monitor information because output generation does result in some
performance decrement. Also, if you enable monitor output by creating
the associated table, your error log may become quite large if you
forget to remove the table later.

For additional information about `InnoDB' monitors, see the following
resources:

   * Mark Leith: InnoDB Table and Tablespace Monitors
     (http://www.markleith.co.uk/?p=25)

   * MySQL Performance Blog: SHOW INNODB STATUS walk through
     (http://www.mysqlperformanceblog.com/2006/07/17/show-innodb-status-walk-through/)

Each monitor begins with a header containing a timestamp and the
monitor name. For example:

     ================================================
     090407 12:06:19 INNODB TABLESPACE MONITOR OUTPUT
     ================================================

The header for the standard Monitor (`INNODB MONITOR OUTPUT') is also
used for the Lock Monitor because the latter produces the same output
with the addition of extra lock information.

The following sections describe the output for each Monitor.


File: manual.info,  Node: innodb-general-monitor,  Next: innodb-tablespace-monitor,  Prev: innodb-monitors,  Up: innodb-monitors

13.7.13.3 `InnoDB' Standard and Lock Monitor Output
...................................................

The Lock Monitor is the same as the standard Monitor except that it
includes additional lock information. Enabling either monitor for
periodic output by creating the associated `InnoDB' table turns on the
same output stream, but the stream includes the extra information if the
Lock Monitor is enabled. For example, if you create the
`innodb_monitor' and `innodb_lock_monitor' tables, that turns on a
single output stream. The stream includes extra lock information until
you disable the Lock Monitor by removing the `innodb_lock_monitor'
table.

Example `InnoDB' Monitor output:

     mysql> SHOW ENGINE INNODB STATUS\G
     *************************** 1. row ***************************
     Status:
     =====================================
     030709 13:00:59 INNODB MONITOR OUTPUT
     =====================================
     Per second averages calculated from the last 18 seconds
     ----------
     SEMAPHORES
     ----------
     OS WAIT ARRAY INFO: reservation count 413452, signal count 378357
     --Thread 32782 has waited at btr0sea.c line 1477 for 0.00 seconds the
     semaphore: X-lock on RW-latch at 41a28668 created in file btr0sea.c line 135
     a writer (thread id 32782) has reserved it in mode wait exclusive
     number of readers 1, waiters flag 1
     Last time read locked in file btr0sea.c line 731
     Last time write locked in file btr0sea.c line 1347
     Mutex spin waits 0, rounds 0, OS waits 0
     RW-shared spins 108462, OS waits 37964; RW-excl spins 681824, OS waits
     375485
     ------------------------
     LATEST FOREIGN KEY ERROR
     ------------------------
     030709 13:00:59 Transaction:
     TRANSACTION 0 290328284, ACTIVE 0 sec, process no 3195, OS thread id 34831
     inserting
     15 lock struct(s), heap size 2496, undo log entries 9
     MySQL thread id 25, query id 4668733 localhost heikki update
     insert into ibtest11a (D, B, C) values (5, 'khDk' ,'khDk')
     Foreign key constraint fails for table test/ibtest11a:
     ,
       CONSTRAINT `0_219242` FOREIGN KEY (`A`, `D`) REFERENCES `ibtest11b` (`A`,
       `D`) ON DELETE CASCADE ON UPDATE CASCADE
     Trying to add in child table, in index PRIMARY tuple:
      0: len 4; hex 80000101; asc ....;; 1: len 4; hex 80000005; asc ....;; 2:
      len 4; hex 6b68446b; asc khDk;; 3: len 6; hex 0000114e0edc; asc ...N..;; 4:
      len 7; hex 00000000c3e0a7; asc .......;; 5: len 4; hex 6b68446b; asc khDk;;
     But in parent table test/ibtest11b, in index PRIMARY,
     the closest match we can find is record:
     RECORD: info bits 0 0: len 4; hex 8000015b; asc ...[;; 1: len 4; hex
     80000005; asc ....;; 2: len 3; hex 6b6864; asc khd;; 3: len 6; hex
     0000111ef3eb; asc ......;; 4: len 7; hex 800001001e0084; asc .......;; 5:
     len 3; hex 6b6864; asc khd;;
     ------------------------
     LATEST DETECTED DEADLOCK
     ------------------------
     030709 12:59:58
     *** (1) TRANSACTION:
     TRANSACTION 0 290252780, ACTIVE 1 sec, process no 3185, OS thread id 30733
     inserting
     LOCK WAIT 3 lock struct(s), heap size 320, undo log entries 146
     MySQL thread id 21, query id 4553379 localhost heikki update
     INSERT INTO alex1 VALUES(86, 86, 794,'aA35818','bb','c79166','d4766t',
     'e187358f','g84586','h794',date_format('2001-04-03 12:54:22','%Y-%m-%d
     %H:%i'),7
     *** (1) WAITING FOR THIS LOCK TO BE GRANTED:
     RECORD LOCKS space id 0 page no 48310 n bits 568 table test/alex1 index
     symbole trx id 0 290252780 lock mode S waiting
     Record lock, heap no 324 RECORD: info bits 0 0: len 7; hex 61613335383138;
     asc aa35818;; 1:
     *** (2) TRANSACTION:
     TRANSACTION 0 290251546, ACTIVE 2 sec, process no 3190, OS thread id 32782
     inserting
     130 lock struct(s), heap size 11584, undo log entries 437
     MySQL thread id 23, query id 4554396 localhost heikki update
     REPLACE INTO alex1 VALUES(NULL, 32, NULL,'aa3572','','c3572','d6012t','',
     NULL,'h396', NULL, NULL, 7.31,7.31,7.31,200)
     *** (2) HOLDS THE LOCK(S):
     RECORD LOCKS space id 0 page no 48310 n bits 568 table test/alex1 index
     symbole trx id 0 290251546 lock_mode X locks rec but not gap
     Record lock, heap no 324 RECORD: info bits 0 0: len 7; hex 61613335383138;
     asc aa35818;; 1:
     *** (2) WAITING FOR THIS LOCK TO BE GRANTED:
     RECORD LOCKS space id 0 page no 48310 n bits 568 table test/alex1 index
     symbole trx id 0 290251546 lock_mode X locks gap before rec insert intention
     waiting
     Record lock, heap no 82 RECORD: info bits 0 0: len 7; hex 61613335373230;
     asc aa35720;; 1:
     *** WE ROLL BACK TRANSACTION (1)
     ------------
     TRANSACTIONS
     ------------
     Trx id counter 0 290328385
     Purge done for trx's n:o < 0 290315608 undo n:o < 0 17
     Total number of lock structs in row lock hash table 70
     LIST OF TRANSACTIONS FOR EACH SESSION:
     ---TRANSACTION 0 0, not started, process no 3491, OS thread id 42002
     MySQL thread id 32, query id 4668737 localhost heikki
     show innodb status
     ---TRANSACTION 0 290328384, ACTIVE 0 sec, process no 3205, OS thread id
     38929 inserting
     1 lock struct(s), heap size 320
     MySQL thread id 29, query id 4668736 localhost heikki update
     insert into speedc values (1519229,1, 'hgjhjgghggjgjgjgjgjggjgjgjgjgjgggjgjg
     jlhhgghggggghhjhghgggggghjhghghghghghhhhghghghjhhjghjghjkghjghjghjghjfhjfh
     ---TRANSACTION 0 290328383, ACTIVE 0 sec, process no 3180, OS thread id
     28684 committing
     1 lock struct(s), heap size 320, undo log entries 1
     MySQL thread id 19, query id 4668734 localhost heikki update
     insert into speedcm values (1603393,1, 'hgjhjgghggjgjgjgjgjggjgjgjgjgjgggjgj
     gjlhhgghggggghhjhghgggggghjhghghghghghhhhghghghjhhjghjghjkghjghjghjghjfhjf
     ---TRANSACTION 0 290328327, ACTIVE 0 sec, process no 3200, OS thread id
     36880 starting index read
     LOCK WAIT 2 lock struct(s), heap size 320
     MySQL thread id 27, query id 4668644 localhost heikki Searching rows for
     update
     update ibtest11a set B = 'kHdkkkk' where A = 89572
     ------- TRX HAS BEEN WAITING 0 SEC FOR THIS LOCK TO BE GRANTED:
     RECORD LOCKS space id 0 page no 65556 n bits 232 table test/ibtest11a index
     PRIMARY trx id 0 290328327 lock_mode X waiting
     Record lock, heap no 1 RECORD: info bits 0 0: len 9; hex 73757072656d756d00;
     asc supremum.;;
     ------------------
     ---TRANSACTION 0 290328284, ACTIVE 0 sec, process no 3195, OS thread id
     34831 rollback of SQL statement
     ROLLING BACK 14 lock struct(s), heap size 2496, undo log entries 9
     MySQL thread id 25, query id 4668733 localhost heikki update
     insert into ibtest11a (D, B, C) values (5, 'khDk' ,'khDk')
     ---TRANSACTION 0 290327208, ACTIVE 1 sec, process no 3190, OS thread id
     32782
     58 lock struct(s), heap size 5504, undo log entries 159
     MySQL thread id 23, query id 4668732 localhost heikki update
     REPLACE INTO alex1 VALUES(86, 46, 538,'aa95666','bb','c95666','d9486t',
     'e200498f','g86814','h538',date_format('2001-04-03 12:54:22','%Y-%m-%d
     %H:%i'),
     ---TRANSACTION 0 290323325, ACTIVE 3 sec, process no 3185, OS thread id
     30733 inserting
     4 lock struct(s), heap size 1024, undo log entries 165
     MySQL thread id 21, query id 4668735 localhost heikki update
     INSERT INTO alex1 VALUES(NULL, 49, NULL,'aa42837','','c56319','d1719t','',
     NULL,'h321', NULL, NULL, 7.31,7.31,7.31,200)
     --------
     FILE I/O
     --------
     I/O thread 0 state: waiting for i/o request (insert buffer thread)
     I/O thread 1 state: waiting for i/o request (log thread)
     I/O thread 2 state: waiting for i/o request (read thread)
     I/O thread 3 state: waiting for i/o request (write thread)
     Pending normal aio reads: 0, aio writes: 0,
      ibuf aio reads: 0, log i/o's: 0, sync i/o's: 0
     Pending flushes (fsync) log: 0; buffer pool: 0
     151671 OS file reads, 94747 OS file writes, 8750 OS fsyncs
     25.44 reads/s, 18494 avg bytes/read, 17.55 writes/s, 2.33 fsyncs/s
     -------------------------------------
     INSERT BUFFER AND ADAPTIVE HASH INDEX
     -------------------------------------
     Ibuf for space 0: size 1, free list len 19, seg size 21,
     85004 inserts, 85004 merged recs, 26669 merges
     Hash table size 207619, used cells 14461, node heap has 16 buffer(s)
     1877.67 hash searches/s, 5121.10 non-hash searches/s
     ---
     LOG
     ---
     Log sequence number 18 1212842764
     Log flushed up to   18 1212665295
     Last checkpoint at  18 1135877290
     0 pending log writes, 0 pending chkp writes
     4341 log i/o's done, 1.22 log i/o's/second
     ----------------------
     BUFFER POOL AND MEMORY
     ----------------------
     Total memory allocated 84966343; in additional pool allocated 1402624
     Buffer pool size   3200
     Free buffers       110
     Database pages     3074
     Modified db pages  2674
     Pending reads 0
     Pending writes: LRU 0, flush list 0, single page 0
     Pages read 171380, created 51968, written 194688
     28.72 reads/s, 20.72 creates/s, 47.55 writes/s
     Buffer pool hit rate 999 / 1000
     --------------
     ROW OPERATIONS
     --------------
     0 queries inside InnoDB, 0 queries in queue
     Main thread process no. 3004, id 7176, state: purging
     Number of rows inserted 3738558, updated 127415, deleted 33707, read 755779
     1586.13 inserts/s, 50.89 updates/s, 28.44 deletes/s, 107.88 reads/s
     ----------------------------
     END OF INNODB MONITOR OUTPUT
     ============================

`InnoDB' Monitor output is limited to 64,000 bytes when produced via the
*Note `SHOW ENGINE INNODB STATUS': show-engine. statement. This limit
does not apply to output written to the server's error output.

Some notes on the output sections:

   * `SEMAPHORES'

     This section reports threads waiting for a semaphore and
     statistics on how many times threads have needed a spin or a wait
     on a mutex or a rw-lock semaphore. A large number of threads
     waiting for semaphores may be a result of disk I/O, or contention
     problems inside `InnoDB'. Contention can be due to heavy
     parallelism of queries or problems in operating system thread
     scheduling. Setting the `innodb_thread_concurrency' system
     variable smaller than the default value might help in such
     situations.

   * `LATEST FOREIGN KEY ERROR'

     This section provides information about the most recent foreign
     key constraint error. It is not present if no such error has
     occurred. The contents include the statement that failed as well
     as information about the the constraint that failed and the
     referenced and referencing tables.

   * `LATEST DETECTED DEADLOCK'

     This section provides information about the most recent deadlock.
     It is not present if no deadlock has occurred.  The contents show
     which transactions are involved, the statement each was attempting
     to execute, the locks they have and need, and which transaction
     `InnoDB' decided to roll back to break the deadlock. The lock
     modes reported in this section are explained in *Note
     innodb-lock-modes::.

   * `TRANSACTIONS'

     If this section reports lock waits, your applications might have
     lock contention. The output can also help to trace the reasons for
     transaction deadlocks.

   * `FILE I/O'

     This section provides information about threads that `InnoDB' uses
     to perform various types of I/O. The first few of these are
     dedicated to general `InnoDB' processing. The contents also
     display information for pending I/O operations and statistics for
     I/O performance.

     On Unix, the number of threads is always 4. On Windows, the number
     depends on the setting of the `innodb_file_io_threads' system
     variable.

   * `INSERT BUFFER AND ADAPTIVE HASH INDEX'

     This section shows the status of the `InnoDB' insert buffer and
     adaptive hash index. (See *Note innodb-insert-buffering::, and
     *Note innodb-adaptive-hash::.) The contents include the number of
     operations performed for each, plus statistics for hash index
     performance.

   * `LOG'

     This section displays information about the `InnoDB' log. The
     contents include the current log sequence number, how far the log
     has been flushed to disk, and the position at which `InnoDB' last
     took a checkpoint. (See *Note innodb-checkpoints::.) The section
     also displays information about pending writes and write
     performance statistics.

   * `BUFFER POOL AND MEMORY'

     This section gives you statistics on pages read and written. You
     can calculate from these numbers how many data file I/O operations
     your queries currently are doing.

   * `ROW OPERATIONS'

     This section shows what the main thread is doing, including the
     number and performance rate for each type of row operation.


File: manual.info,  Node: innodb-tablespace-monitor,  Next: innodb-table-monitor,  Prev: innodb-general-monitor,  Up: innodb-monitors

13.7.13.4 `InnoDB' Tablespace Monitor Output
............................................

The `InnoDB' Tablespace Monitor prints information about the file
segments in the shared tablespace and validates the tablespace
allocation data structures. If you use individual tablespaces by
enabling `innodb_file_per_table', the Tablespace Monitor does not
describe those tablespaces.

Example `InnoDB' Tablespace Monitor output:

     ================================================
     090408 21:28:09 INNODB TABLESPACE MONITOR OUTPUT
     ================================================
     FILE SPACE INFO: id 0
     size 13440, free limit 3136, free extents 28
     not full frag extents 2: used pages 78, full frag extents 3
     first seg id not used 0 23845
     SEGMENT id 0 1 space 0; page 2; res 96 used 46; full ext 0
     fragm pages 32; free extents 0; not full extents 1: pages 14
     SEGMENT id 0 2 space 0; page 2; res 1 used 1; full ext 0
     fragm pages 1; free extents 0; not full extents 0: pages 0
     SEGMENT id 0 3 space 0; page 2; res 1 used 1; full ext 0
     fragm pages 1; free extents 0; not full extents 0: pages 0
     ...
     SEGMENT id 0 15 space 0; page 2; res 160 used 160; full ext 2
     fragm pages 32; free extents 0; not full extents 0: pages 0
     SEGMENT id 0 488 space 0; page 2; res 1 used 1; full ext 0
     fragm pages 1; free extents 0; not full extents 0: pages 0
     SEGMENT id 0 17 space 0; page 2; res 1 used 1; full ext 0
     fragm pages 1; free extents 0; not full extents 0: pages 0
     ...
     SEGMENT id 0 171 space 0; page 2; res 592 used 481; full ext 7
     fragm pages 16; free extents 0; not full extents 2: pages 17
     SEGMENT id 0 172 space 0; page 2; res 1 used 1; full ext 0
     fragm pages 1; free extents 0; not full extents 0: pages 0
     SEGMENT id 0 173 space 0; page 2; res 96 used 44; full ext 0
     fragm pages 32; free extents 0; not full extents 1: pages 12
     ...
     SEGMENT id 0 601 space 0; page 2; res 1 used 1; full ext 0
     fragm pages 1; free extents 0; not full extents 0: pages 0
     NUMBER of file segments: 73
     Validating tablespace
     Validation ok
     ---------------------------------------
     END OF INNODB TABLESPACE MONITOR OUTPUT
     =======================================

The Tablespace Monitor output includes information about the shared
tablespace as a whole, followed by a list containing a breakdown for
each segment within the tablespace.

The tablespace consists of database pages with a default size of 16KB.
The pages are grouped into extents of size 1MB (64 consecutive pages).

The initial part of the output that displays overall tablespace
information has this format:

     FILE SPACE INFO: id 0
     size 13440, free limit 3136, free extents 28
     not full frag extents 2: used pages 78, full frag extents 3
     first seg id not used 0 23845

Individual segment information has this format:

     SEGMENT id 0 15 space 0; page 2; res 160 used 160; full ext 2
     fragm pages 32; free extents 0; not full extents 0: pages 0

Segment information includes these values:

`id': The segment ID.

`space', `page': The segment `inode' tablespace number and page within
the tablespace. A tablespace number of 0 indicates the shared
tablespace.

`res': The number of pages allocated (reserved) for the segment.

`used': The number of allocated pages in use by the segment.

`full ext': The number of extents allocated for the segment that are
completely used.

`fragm pages': The number of initial pages that have been allocated to
the segment.

`free extents': The number of extents allocated for the segment that
are completely unused.

`not full extents': The number of extents allocated for the segment
that are partially used.

`pages': The number of pages used within the not-full extents.

When a segment grows, it starts as a single page, and `InnoDB'
allocates the first pages for it individually, up to 32 pages (this is
the `fragm pages' value). After that, `InnoDB' allocates complete
64-page extents. `InnoDB' can add up to 4 extents at a time to a large
segment to ensure good sequentiality of data.

For the example segment shown earlier, it has 32 fragment pages, plus 2
full extents (64 pages each), for a total of 160 pages used out of 160
pages allocated. The following segment has 32 fragment pages and one
partially full extent using 14 pages for a total of 46 pages used out
of 96 pages allocated:

     SEGMENT id 0 1 space 0; page 2; res 96 used 46; full ext 0
     fragm pages 32; free extents 0; not full extents 1: pages 14

It is possible for a segment that has extents allocated to it to have a
`fragm pages' value less than 32 if some of the individual pages have
been deallocated subsequent to extent allocation.


File: manual.info,  Node: innodb-table-monitor,  Prev: innodb-tablespace-monitor,  Up: innodb-monitors

13.7.13.5 `InnoDB' Table Monitor Output
.......................................

The `InnoDB' Table Monitor prints the contents of the `InnoDB' internal
data dictionary.

The output contains one section per table. The `SYS_FOREIGN' and
`SYS_FOREIGN_COLS' sections are for internal data dictionary tables
that maintain information about foreign keys. There are also sections
for the Table Monitor table and each user-created `InnoDB' table.
Suppose that the following two tables have been created in the `test'
database:

     CREATE TABLE parent
     (
       par_id    INT NOT NULL,
       fname      CHAR(20),
       lname      CHAR(20),
       PRIMARY KEY (par_id),
       UNIQUE INDEX (lname, fname)
     ) ENGINE = INNODB;

     CREATE TABLE child
     (
       par_id      INT NOT NULL,
       child_id    INT NOT NULL,
       name        VARCHAR(40),
       birth       DATE,
       weight      DECIMAL(10,2),
       misc_info   VARCHAR(255),
       last_update TIMESTAMP,
       PRIMARY KEY (par_id, child_id),
       INDEX (name),
       FOREIGN KEY (par_id) REFERENCES parent (par_id)
         ON DELETE CASCADE
         ON UPDATE CASCADE
     ) ENGINE = INNODB;

Then the Table Monitor output will look something like this
(reformatted slightly):

     ===========================================
     090420 12:11:23 INNODB TABLE MONITOR OUTPUT
     ===========================================
     --------------------------------------
     TABLE: name SYS_FOREIGN, id 0 11, columns 7, indexes 3, appr.rows 1
       COLUMNS: ID: DATA_VARCHAR DATA_ENGLISH len 0;
                FOR_NAME: DATA_VARCHAR DATA_ENGLISH len 0;
                REF_NAME: DATA_VARCHAR DATA_ENGLISH len 0;
                N_COLS: DATA_INT len 4;
                DB_ROW_ID: DATA_SYS prtype 256 len 6;
                DB_TRX_ID: DATA_SYS prtype 257 len 6;
       INDEX: name ID_IND, id 0 11, fields 1/6, uniq 1, type 3
        root page 46, appr.key vals 1, leaf pages 1, size pages 1
        FIELDS:  ID DB_TRX_ID DB_ROLL_PTR FOR_NAME REF_NAME N_COLS
       INDEX: name FOR_IND, id 0 12, fields 1/2, uniq 2, type 0
        root page 47, appr.key vals 1, leaf pages 1, size pages 1
        FIELDS:  FOR_NAME ID
       INDEX: name REF_IND, id 0 13, fields 1/2, uniq 2, type 0
        root page 48, appr.key vals 1, leaf pages 1, size pages 1
        FIELDS:  REF_NAME ID
     --------------------------------------
     TABLE: name SYS_FOREIGN_COLS, id 0 12, columns 7, indexes 1, appr.rows 1
       COLUMNS: ID: DATA_VARCHAR DATA_ENGLISH len 0;
                POS: DATA_INT len 4;
                FOR_COL_NAME: DATA_VARCHAR DATA_ENGLISH len 0;
                REF_COL_NAME: DATA_VARCHAR DATA_ENGLISH len 0;
                DB_ROW_ID: DATA_SYS prtype 256 len 6;
                DB_TRX_ID: DATA_SYS prtype 257 len 6;
       INDEX: name ID_IND, id 0 14, fields 2/6, uniq 2, type 3
        root page 49, appr.key vals 1, leaf pages 1, size pages 1
        FIELDS:  ID POS DB_TRX_ID DB_ROLL_PTR FOR_COL_NAME REF_COL_NAME
     --------------------------------------
     TABLE: name test/child, id 0 14, columns 10, indexes 2, appr.rows 201
       COLUMNS: par_id: DATA_INT DATA_BINARY_TYPE DATA_NOT_NULL len 4;
                child_id: DATA_INT DATA_BINARY_TYPE DATA_NOT_NULL len 4;
                name: DATA_VARCHAR prtype 524303 len 40;
                birth: DATA_INT DATA_BINARY_TYPE len 3;
                weight: DATA_FIXBINARY DATA_BINARY_TYPE len 5;
                misc_info: DATA_VARCHAR prtype 524303 len 255;
                last_update: DATA_INT DATA_UNSIGNED DATA_BINARY_TYPE DATA_NOT_NULL len 4;
                DB_ROW_ID: DATA_SYS prtype 256 len 6;
                DB_TRX_ID: DATA_SYS prtype 257 len 6;
       INDEX: name PRIMARY, id 0 17, fields 2/9, uniq 2, type 3
        root page 52, appr.key vals 201, leaf pages 5, size pages 6
        FIELDS:  par_id child_id DB_TRX_ID DB_ROLL_PTR name birth weight misc_info last_update
       INDEX: name name, id 0 18, fields 1/3, uniq 3, type 0
        root page 53, appr.key vals 210, leaf pages 1, size pages 1
        FIELDS:  name par_id child_id
       FOREIGN KEY CONSTRAINT test/child_ibfk_1: test/child ( par_id )
                  REFERENCES test/parent ( par_id )
     --------------------------------------
     TABLE: name test/innodb_table_monitor, id 0 15, columns 4, indexes 1, appr.rows 0
       COLUMNS: i: DATA_INT DATA_BINARY_TYPE len 4;
                DB_ROW_ID: DATA_SYS prtype 256 len 6;
                DB_TRX_ID: DATA_SYS prtype 257 len 6;
       INDEX: name GEN_CLUST_INDEX, id 0 19, fields 0/4, uniq 1, type 1
        root page 62, appr.key vals 0, leaf pages 1, size pages 1
        FIELDS:  DB_ROW_ID DB_TRX_ID DB_ROLL_PTR i
     --------------------------------------
     TABLE: name test/parent, id 0 13, columns 6, indexes 2, appr.rows 299
       COLUMNS: par_id: DATA_INT DATA_BINARY_TYPE DATA_NOT_NULL len 4;
                fname: DATA_CHAR prtype 524542 len 20;
                lname: DATA_CHAR prtype 524542 len 20;
                DB_ROW_ID: DATA_SYS prtype 256 len 6;
                DB_TRX_ID: DATA_SYS prtype 257 len 6;
       INDEX: name PRIMARY, id 0 15, fields 1/5, uniq 1, type 3
        root page 50, appr.key vals 299, leaf pages 2, size pages 3
        FIELDS:  par_id DB_TRX_ID DB_ROLL_PTR fname lname
       INDEX: name lname, id 0 16, fields 2/3, uniq 2, type 2
        root page 51, appr.key vals 300, leaf pages 1, size pages 1
        FIELDS:  lname fname par_id
       FOREIGN KEY CONSTRAINT test/child_ibfk_1: test/child ( par_id )
                  REFERENCES test/parent ( par_id )
     -----------------------------------
     END OF INNODB TABLE MONITOR OUTPUT
     ==================================

For each table, Table Monitor output contains a section that displays
general information about the table and specific information about its
columns, indexes, and foreign keys.

The general information for each table includes the table name (in
`DB_NAME/TBL_NAME' format except for internal tables), its ID, the
number of columns and indexes, and an approximate row count.

The `COLUMNS' part of a table section lists each column in the table.
Information for each column indicates its name and data type
characteristics. Some internal columns are added by `InnoDB', such as
`DB_ROW_ID' (row ID) and `DB_TRX_ID' (transaction ID).

   * `DATA_XXX': These symbols indicate the data type. There may be
     multiple `DATA_XXX' symbols for a given column.

   * `prtype': The column's `precise' type. This field includes
     information such as the column data type, character set code,
     nullability, signedness, and whether it is a binary string. This
     field is described in the `innobase/include/data0type.h' source
     file.

   * `len': The column length in bytes.

Each `INDEX' part of the table section provides the name and
characteristics of one table index:

   * `name': The index name. If the name is `PRIMARY', the index is a
     primary key. If the name is `GEN_CLUST_INDEX', the index is the
     clustered index that is created automatically if the table
     definition doesn't include a primary key or non-`NULL' unique
     index. See *Note innodb-index-types::.

   * `id': The index ID.

   * `fields': The number of fields in the index, as a value in `M/N'
     format:

        * M is the number of user-defined columns; that is, the number
          of columns you would see in the index definition in a `CREATE
          TABLE' statement.

        * N is the total number of index columns, including those added
          internally. For the clustered index, the total includes the
          other columns in the table definition, plus any columns added
          internally. For a secondary index, the total includes the
          columns from the primary key that are not part of the
          secondary index.

   * `uniq': The number of leading fields that are enough to determine
     index values uniquely.

   * `type': The index type. This is a bit field. For example, 1
     indicates a clustered index and 2 indicates a unique index, so a
     clustered index (which always contains unique values), will have a
     `type' value of 3. An index with a `type' value of 0 is neither
     clustered nor unique. The flag values are defined in the
     `innobase/include/dict0mem.h' source file.

   * `root page': The index root page number.

   * `appr. key vals': The approximate index cardinality.

   * `leaf pages': The approximate number of leaf pages in the index.

   * `size pages': The approximate total number of pages in the index.

   * `FIELDS': The names of the fields in the index. For a clustered
     index that was generated automatically, the field list begins with
     the internal `DB_ROW_ID' (row ID) field.  `DB_TRX_ID' and
     `DB_ROLL_PTR' are always added internally to the clustered index,
     following the fields that comprise the primary key. For a
     secondary index, the final fields are those from the primary key
     that are not part of the secondary index.

The end of the table section lists the `FOREIGN KEY' definitions that
apply to the table. This information appears whether the table is a
referencing or referenced table.


File: manual.info,  Node: innodb-troubleshooting,  Next: innodb-troubleshooting-datadict,  Prev: innodb-monitors,  Up: innodb-tuning-troubleshooting

13.7.13.6 `InnoDB' General Troubleshooting
..........................................

The following general guidelines apply to troubleshooting `InnoDB'
problems:

   * When an operation fails or you suspect a bug, you should look at
     the MySQL server error log (see *Note error-log::).

   * When troubleshooting, it is usually best to run the MySQL server
     from the command prompt, rather than through *Note `mysqld_safe':
     mysqld-safe. or as a Windows service. You can then see what *Note
     `mysqld': mysqld. prints to the console, and so have a better
     grasp of what is going on. On Windows, start *Note `mysqld':
     mysqld. with the `--console' option to direct the output to the
     console window.

   * Use the `InnoDB' Monitors to obtain information about a problem
     (see *Note innodb-monitors::). If the problem is
     performance-related, or your server appears to be hung, you should
     use the standard Monitor to print information about the internal
     state of `InnoDB'. If the problem is with locks, use the Lock
     Monitor. If the problem is in creation of tables or other data
     dictionary operations, use the Table Monitor to print the contents
     of the `InnoDB' internal data dictionary. To see tablespace
     information use the Tablespace Monitor.

   * If you suspect that a table is corrupt, run *Note `CHECK TABLE':
     check-table. on that table.

MySQL Enterprise

The MySQL Enterprise Monitor provides a number of advisors specifically
designed for monitoring InnoDB tables. In some cases, these advisors
can anticipate potential problems. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: innodb-troubleshooting-datadict,  Prev: innodb-troubleshooting,  Up: innodb-tuning-troubleshooting

13.7.13.7 Troubleshooting `InnoDB' Data Dictionary Operations
.............................................................

A specific issue with tables is that the MySQL server keeps data
dictionary information in `.frm' files it stores in the database
directories, whereas `InnoDB' also stores the information into its own
data dictionary inside the tablespace files. If you move `.frm' files
around, or if the server crashes in the middle of a data dictionary
operation, the locations of the `.frm' files may end up out of synchrony
with the locations recorded in the `InnoDB' internal data dictionary.

A symptom of an out-of-sync data dictionary is that a *Note `CREATE
TABLE': create-table. statement fails. If this occurs, you should look
in the server's error log. If the log says that the table already
exists inside the `InnoDB' internal data dictionary, you have an
orphaned table inside the `InnoDB' tablespace files that has no
corresponding `.frm' file.  The error message looks like this:

     InnoDB: Error: table test/parent already exists in InnoDB internal
     InnoDB: data dictionary. Have you deleted the .frm file
     InnoDB: and not used DROP TABLE? Have you used DROP DATABASE
     InnoDB: for InnoDB tables in MySQL version <= 3.23.43?
     InnoDB: See the Restrictions section of the InnoDB manual.
     InnoDB: You can drop the orphaned table inside InnoDB by
     InnoDB: creating an InnoDB table with the same name in another
     InnoDB: database and moving the .frm file to the current database.
     InnoDB: Then MySQL thinks the table exists, and DROP TABLE will
     InnoDB: succeed.

You can drop the orphaned table by following the instructions given in
the error message. If you are still unable to use *Note `DROP TABLE':
drop-table. successfully, the problem may be due to name completion in
the *Note `mysql': mysql. client. To work around this problem, start
the *Note `mysql': mysql. client with the `--skip-auto-rehash' option
and try *Note `DROP TABLE': drop-table. again.  (With name completion
on, *Note `mysql': mysql. tries to construct a list of table names,
which fails when a problem such as just described exists.)

Another symptom of an out-of-sync data dictionary is that MySQL prints
an error that it cannot open a `.InnoDB' file:

     ERROR 1016: Can't open file: 'child2.InnoDB'. (errno: 1)

In the error log you can find a message like this:

     InnoDB: Cannot find table test/child2 from the internal data dictionary
     InnoDB: of InnoDB though the .frm file for the table exists. Maybe you
     InnoDB: have deleted and recreated InnoDB data files but have forgotten
     InnoDB: to delete the corresponding .frm files of InnoDB tables?

This means that there is an orphaned `.frm' file without a
corresponding table inside `InnoDB'. You can drop the orphaned `.frm'
file by deleting it manually.

If MySQL crashes in the middle of an *Note `ALTER TABLE': alter-table.
operation, you may end up with an orphaned temporary table inside the
`InnoDB' tablespace.  Using the Table Monitor, you can see listed a
table with a name that begins with `#sql-'. You can perform SQL
statements on tables whose name contains the character ``#'' if you
enclose the name within backticks. Thus, you can drop such an orphaned
table like any other orphaned table using the method described earlier.
To copy or rename a file in the Unix shell, you need to put the file
name in double quotes if the file name contains ``#''.


File: manual.info,  Node: innodb-restrictions,  Prev: innodb-tuning-troubleshooting,  Up: innodb

13.7.14 Restrictions on `InnoDB' Tables
---------------------------------------

*Warning*:

Do _not_ convert MySQL system tables in the `mysql' database from
`MyISAM' to `InnoDB' tables! This is an unsupported operation. If you
do this, MySQL does not restart until you restore the old system tables
from a backup or re-generate them with the *Note `mysql_install_db':
mysql-install-db. script.

*Warning*:

It is not a good idea to configure `InnoDB' to use data files or log
files on NFS volumes. Otherwise, the files might be locked by other
processes and become unavailable for use by MySQL.

   * A table cannot contain more than 1000 columns.

   * The `InnoDB' internal maximum key length is 3500 bytes, but MySQL
     itself restricts this to 3072 bytes.

   * Index key prefixes can be up to 767 bytes. See *Note
     create-index::.

   * The maximum row length, except for variable-length columns (*Note
     `VARBINARY': binary-varbinary, *Note `VARCHAR': char, *Note
     `BLOB': blob. and *Note `TEXT': blob.), is slightly less than half
     of a database page. That is, the maximum row length is about 8000
     bytes. *Note `LONGBLOB': blob. and *Note `LONGTEXT': blob. columns
     must be less than 4GB, and the total row length, including *Note
     `BLOB': blob. and *Note `TEXT': blob. columns, must be less than
     4GB.

     If a row is less than half a page long, all of it is stored
     locally within the page. If it exceeds half a page,
     variable-length columns are chosen for external off-page storage
     until the row fits within half a page, as described in *Note
     innodb-file-space::.

   * Although `InnoDB' supports row sizes larger than 65535 internally,
     you cannot define a row containing *Note `VARBINARY':
     binary-varbinary. or *Note `VARCHAR': char. columns with a combined
     size larger than 65535:

          mysql> CREATE TABLE t (a VARCHAR(8000), b VARCHAR(10000),
              -> c VARCHAR(10000), d VARCHAR(10000), e VARCHAR(10000),
              -> f VARCHAR(10000), g VARCHAR(10000)) ENGINE=InnoDB;
          ERROR 1118 (42000): Row size too large. The maximum row size for the
          used table type, not counting BLOBs, is 65535. You have to change some
          columns to TEXT or BLOBs

   * On some older operating systems, files must be less than 2GB.
     This is not a limitation of `InnoDB' itself, but if you require a
     large tablespace, you will need to configure it using several
     smaller data files rather than one or a file large data files.

   * The combined size of the `InnoDB' log files must be less than 4GB.

   * The minimum tablespace size is 10MB. The maximum tablespace size
     is four billion database pages (64TB). This is also the maximum
     size for a table.

   * `InnoDB' tables do not support `FULLTEXT' indexes.

   * `InnoDB' tables support spatial data types, but not indexes on
     them.

   * *Note `ANALYZE TABLE': analyze-table. determines index cardinality
     (as displayed in the `Cardinality' column of *Note `SHOW INDEX':
     show-index. output) by doing ten random dives to each of the index
     trees and updating index cardinality estimates accordingly.
     Because these are only estimates, repeated runs of *Note `ANALYZE
     TABLE': analyze-table. may produce different numbers. This makes
     *Note `ANALYZE TABLE': analyze-table. fast on `InnoDB' tables but
     not 100% accurate because it does not take all rows into account.

     MySQL uses index cardinality estimates only in join optimization.
     If some join is not optimized in the right way, you can try using
     *Note `ANALYZE TABLE': analyze-table. In the few cases that *Note
     `ANALYZE TABLE': analyze-table. does not produce values good
     enough for your particular tables, you can use `FORCE INDEX' with
     your queries to force the use of a particular index, or set the
     `max_seeks_for_key' system variable to ensure that MySQL prefers
     index lookups over table scans. See *Note
     server-system-variables::, and *Note optimizer-issues::.

   * *Note `SHOW TABLE STATUS': show-table-status. does not give
     accurate statistics on `InnoDB' tables, except for the physical
     size reserved by the table. The row count is only a rough estimate
     used in SQL optimization.

   * `InnoDB' does not keep an internal count of rows in a table. (In
     practice, this would be somewhat complicated due to
     multi-versioning.) To process a `SELECT COUNT(*) FROM t' statement,
     `InnoDB' must scan an index of the table, which takes some time if
     the index is not entirely in the buffer pool. If your table does
     not change often, using the MySQL query cache is a good solution.
     To get a fast count, you have to use a counter table you create
     yourself and let your application update it according to the
     inserts and deletes it does. *Note `SHOW TABLE STATUS':
     show-table-status. also can be used if an approximate row count is
     sufficient. See *Note innodb-tuning::.

   * On Windows, `InnoDB' always stores database and table names
     internally in lowercase. To move databases in a binary format from
     Unix to Windows or from Windows to Unix, you should create all
     databases and tables using lowercase names.

   * For an `AUTO_INCREMENT' column, you must always define an index
     for the table, and that index must contain just the
     `AUTO_INCREMENT' column. In `MyISAM' tables, the `AUTO_INCREMENT'
     column may be part of a multi-column index.

   * While initializing a previously specified `AUTO_INCREMENT' column
     on a table, `InnoDB' sets an exclusive lock on the end of the
     index associated with the `AUTO_INCREMENT' column. In accessing the
     auto-increment counter, `InnoDB' uses a specific table lock mode
     `AUTO-INC' where the lock lasts only to the end of the current SQL
     statement, not to the end of the entire transaction. Other clients
     cannot insert into the table while the `AUTO-INC' table lock is
     held; see *Note innodb-auto-increment-handling::.

   * When you restart the MySQL server, `InnoDB' may reuse an old value
     that was generated for an `AUTO_INCREMENT' column but never stored
     (that is, a value that was generated during an old transaction
     that was rolled back).

   * When an `AUTO_INCREMENT' column runs out of values, `InnoDB' wraps
     a *Note `BIGINT': numeric-types. to `-9223372036854775808' and
     `BIGINT UNSIGNED' to `1'. However, *Note `BIGINT': numeric-types.
     values have 64 bits, so if you were to insert one million rows per
     second, it would still take nearly three hundred thousand years
     before *Note `BIGINT': numeric-types. reached its upper bound.
     With all other integer type columns, a duplicate-key error
     results. This is similar to how `MyISAM' works, because it is
     mostly general MySQL behavior and not about any storage engine in
     particular.

   * `DELETE FROM TBL_NAME' does not regenerate the table but instead
     deletes all rows, one by one.

   * Under some conditions, `TRUNCATE TBL_NAME' for an `InnoDB' table
     is mapped to `DELETE FROM TBL_NAME'. See *Note truncate::.

   * In MySQL 6.0, the MySQL *Note `LOCK TABLES': lock-tables.
     operation acquires two locks on each table if `innodb_table_locks
     = 1' (the default). In addition to a table lock on the MySQL
     layer, it also acquires an `InnoDB' table lock. Older versions of
     MySQL did not acquire `InnoDB' table locks; the old behavior can
     be selected by setting `innodb_table_locks = 0'. If no `InnoDB'
     table lock is acquired, *Note `LOCK TABLES': lock-tables.
     completes even if some records of the tables are being locked by
     other transactions.

   * All `InnoDB' locks held by a transaction are released when the
     transaction is committed or aborted. Thus, it does not make much
     sense to invoke *Note `LOCK TABLES': lock-tables. on `InnoDB'
     tables in `autocommit = 1' mode, because the acquired `InnoDB'
     table locks would be released immediately.

   * Sometimes it would be useful to lock further tables in the course
     of a transaction. Unfortunately, *Note `LOCK TABLES': lock-tables.
     in MySQL performs an implicit *Note `COMMIT': commit. and *Note
     `UNLOCK TABLES': lock-tables. if you use non-transactional locks.
     As of MySQL 6.0, *Note `LOCK TABLES': lock-tables. supports
     transactional locks that can be executed in the middle of a
     transaction.

   * The default database page size in `InnoDB' is 16KB. By recompiling
     the code, you can set it to values ranging from 8KB to 64KB. You
     must update the values of `UNIV_PAGE_SIZE' and
     `UNIV_PAGE_SIZE_SHIFT' in the `univ.i' source file.

   * Currently, cascaded foreign key actions to not activate triggers.

   * You cannot create a table with a column name that matches the name
     of an internal InnoDB column (including `DB_ROW_ID', `DB_TRX_ID',
     `DB_ROLL_PTR', and `DB_MIX_ID'). The server will report error 1005
     and refers to error -1 in the error message. This limitation
     applies only to use of the names in uppercase.

   * `InnoDB' has a limit of 1023 concurrent transactions that have
     created undo records by modifying data.  Workarounds include
     keeping transactions as small and fast as possible, delaying
     changes until near the end of the transaction, and using stored
     routines to reduce client-server latency delays. Applications
     should commit transactions before doing time-consuming client-side
     operations.


File: manual.info,  Node: se-falcon,  Next: merge-storage-engine,  Prev: innodb,  Up: storage-engines

13.8 The `Falcon' Storage Engine
================================

* Menu:

* se-falcon-features::           `Falcon' Features
* se-falcon-configuration::      Configuration Parameters
* se-falcon-createdb::           Creating the `Falcon' Tablespace
* se-falcon-createtable::        Creating Tables and Indexes within `Falcon'
* se-falcon-stats::              Obtaining Performance Diagnostics
* se-falcon-principles::         Principles and Terminology
* se-falcon-limits::             Notes and Limits
* se-falcon-roadmap::            `Falcon' Roadmap

The `Falcon' Storage Engine has been designed with modern database
requirements in mind, and particularly for use within high-volume web
serving or other environment that requires high performance, while
still supporting the transactional and logging functionality required
in this environment.

*Falcon Features*

*Storage limits* 512ZB    *Transactions*   Yes      *Locking         Row
                                                    granularity*     
*MVCC*           Yes      *Geospatial      No       *Geospatial      No
                          datatype                  indexing         
                          support*                  support*         
*B-tree indexes* Yes      *Hash indexes*   No       *Full-text       No
                                                    search indexes*  
*Clustered       No       *Data caches*    Yes      *Index caches*   Yes
indexes*                                                             
*Compressed      Yes      *Encrypted data  Yes      *Cluster         No
data*                     Implemented in            database         
                          the server (via           support*         
                          encryption                                 
                          functions),                                
                          rather than in                             
                          the storage                                
                          engine.*                                   
*Replication     Yes      *Foreign key     No       *Backup /        Yes
support                   support*                  point-in-time    
Implemented in                                      recovery         
the server,                                         Implemented in   
rather than in                                      the server,      
the storage                                         rather than in   
engine*                                             the storage      
                                                    engine*          
*Query cache     Yes      *Update          Yes                       
support*                  statistics for                             
                          data dictionary*                           

`Falcon' is available for the 32-bit Windows and 32-bit or 64-bit Linux
operating systems. As of MySQL 6.0.4 and later, support is also
provided for Mac OS X on x86 or PowerPC and Solaris/Linux on SPARC
platforms. We intend to support `Falcon' on additional platforms in
future MySQL releases.


File: manual.info,  Node: se-falcon-features,  Next: se-falcon-configuration,  Prev: se-falcon,  Up: se-falcon

13.8.1 `Falcon' Features
------------------------

`Falcon' has been specially developed for systems that are able to
support larger memory architectures and multi-threaded or multi-core
CPU environments. Most 64-bit architectures are ideal platforms for the
`Falcon' engine, where there is a larger available memory space and 2-,
4- or 8-core CPUs available. It can also be deployed within a standard
32-bit environment.

The `Falcon' storage engine is designed to work within high-traffic
transactional applications. It supports a number of key features that
make this possible:

   * Multi Version Concurrency Control (MVCC) enables records and
     tables to be updated without the overhead associated with
     row-level locking mechanisms. The MVCC implementation does not use
     two-phase locking and virtually eliminates the need to lock tables
     or rows during the update process.

   * Flexible locking, including flexible locking levels and smart
     deadlock detection keep data protected and transactions and
     operations flowing at full speed.

   * Optimized for modern CPUs and environments to support multiple
     threads allowing multiple transactions and fast transaction
     handling.

   * Transaction-safe (fully ACID-compliant) and able to handle
     multiple concurrent transactions.

   * Serial Log provides high performance and recovery capabilities
     without sacrificing performance.

   * Advanced B-Tree indexes.

   * Data compression stores the information on disk in a compressed
     format, compressing and decompressing data on the fly. The result
     is in smaller and more efficient physical data sizes.

   * Intelligent disk management automatically manages data files and
     extensions. Space within log and data files is automatically
     reclaimed and reused.

   * Data and index caching provides quick access to data without the
     requirement to load index data from disk.

   * Implicit savepoints ensure data integrity during transactions.

You can test out the `Falcon' storage engine using the MySQL Query
Browser (http://dev.mysql.com/doc/query-browser/en/index.html).


File: manual.info,  Node: se-falcon-configuration,  Next: se-falcon-createdb,  Prev: se-falcon-features,  Up: se-falcon

13.8.2 Configuration Parameters
-------------------------------

Parameters are configured through the standard MySQL `my.cnf' or
`my.ini' file.  Parameters can be configured by specifying the
parameter name and the corresponding value, separated by a space.
Memory values can be specified in bytes, or with a number followed by
`K', `M' or `G'.

*`mysqld' Falcon Option/Variable Reference*

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
falcon                        Yes                                                        Yes                                                                                                                                                                                                                                         
falcon_checkpoint_schedule    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_checksums              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_consistent_read        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
falcon_debug_mask             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_debug_server           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_disable_fsync          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_gopher_threads         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_index_chill_threshold  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_initial_allocation     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_io_threads             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_large_blob_threshold   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_lock_wait_timeout      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_max_transaction_backlogYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_page_cache_size        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_page_size              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_record_chill_threshold Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_record_memory_max      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_record_scavenge_floor  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_record_scavenge_thresholdYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_scavenge_schedule      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_serial_log_buffers     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_serial_log_dir         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_serial_log_priority    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
falcon_use_deferred_index_hashYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_use_sectorcache        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
falcon_use_supernodes         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
skip-falcon                   Yes                                                        Yes                                                                                                                                                                                                                                         

You can obtain a list of variables relevant to `Falcon' using *Note
`SHOW VARIABLES': show-variables.:

     mysql> SHOW VARIABLES LIKE '%falcon%';
     +----------------------------------+------------------------------+
     | Variable_name                    | Value                        |
     +----------------------------------+------------------------------+
     | falcon_checkpoint_schedule       | 7 * * * * *                  |
     | falcon_checksums                 | ON                           |
     | falcon_consistent_read           | ON                           |
     | falcon_debug_mask                | 0                            |
     | falcon_debug_server              | OFF                          |
     | falcon_debug_trace               | 0                            |
     | falcon_direct_io                 | 1                            |
     | falcon_gopher_threads            | 5                            |
     | falcon_index_chill_threshold     | 4194304                      |
     | falcon_io_threads                | 2                            |
     | falcon_large_blob_threshold      | 160000                       |
     | falcon_lock_wait_timeout         | 50                           |
     | falcon_page_cache_size           | 4194304                      |
     | falcon_page_size                 | 4096                         |
     | falcon_record_chill_threshold    | 5242880                      |
     | falcon_record_memory_max         | 262144000                    |
     | falcon_record_scavenge_floor     | 50                           |
     | falcon_record_scavenge_threshold | 67                           |
     | falcon_scavenge_schedule         | 15,45 * * * * *              |
     | falcon_serial_log_block_size     | 0                            |
     | falcon_serial_log_buffers        | 20                           |
     | falcon_serial_log_dir            | /home/jon/bin/mysql-6.0/var/ |
     | falcon_serial_log_file_size      | 10485760                     |
     | falcon_serial_log_priority       | 1                            |
     | falcon_support_xa                | OFF                          |
     | falcon_use_deferred_index_hash   | OFF                          |
     | falcon_use_sectorcache           | OFF                          |
     | falcon_use_supernodes            | ON                           |
     +----------------------------------+------------------------------+

   *  `falcon'

     *Version Introduced* 6.0.0
     *Command Line        `falcon'
     Format*              
     *Config File Format* `falcon'
     *Value Set *         
     Typeboolean          
     Defaultyes           

     Enables the `Falcon' storage engine.

   *  `skip-falcon'

     *Version Introduced* 6.0.0
     *Command Line        `--skip-falcon'
     Format*              
     *Config File Format* `skip-falcon'

     Disables the `Falcon' storage engine.

   *  `falcon_checkpoint_schedule'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_checkpoint_schedule'
     Format*              
     *Config File Format* `falcon_checkpoint_schedule'
     *Option Sets         Yes, `falcon_checkpoint_schedule'
     Variable*            
     *Variable Name*      `falcon_checkpoint_schedule'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring Default7  
     * * * * *            

     The checkpoint schedule (the frequency with which `fsync()' is
     called to synchronize the in-memory and disk data). Specification
     is in the form of a `crontab'-style series of values, separated by
     spaces. Each specification has six fields, identical to `crontab',
     but with the addition of seconds.  Within the specification, from
     left to right these are:

        * seconds (0-59)

        * minutes (0-59)

        * hours (0-23)

        * day of month (1-31)

        * month (1-12)

        * day of week (0-7, where 0 and 7 are Sunday)

     The values specified can either be absolute, or you can specify a
     range or comma-separated list of matching values.  For example,
     the specification:

          7,37 * * * * *

     Would checkpoint every 7 and 37 seconds of every minute, of every
     hour of ever day. The following specification would checkpoint
     only during 6am and 6pm each day at 0 and 30 seconds of every
     minute.

          0,30 * 6-17 * * *

     The default setting is every minute, seven seconds past the
     minute, i.e.:

          7 * * * * *

   *  `falcon_checksums'

     *Version Introduced* 6.0.6
     *Command Line        `falcon_checksums'
     Format*              
     *Config File Format* `falcon_checksums'
     *Option Sets         Yes, `falcon_checksums'
     Variable*            
     *Variable Name*      `falcon_checksums'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Enable Falcon checksum validation

   *  `falcon_consistent_read'

     *Version Introduced* 6.0.4
     *Command Line        `falcon_consistent_read'
     Format*              
     *Config File Format* `falcon_consistent_read'
     *Option Sets         Yes, `falcon_consistent_read'
     Variable*            
     *Variable Name*      `falcon_consistent_read'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultON            

     Sets the repeatable read transaction isolation level. Set to On,
     repeatable read transactions are truly consistent-read.  Changes
     made by younger transactions will not be exposed and newer records
     cannot be read or written within a repeatable read transaction.
     Set to Off, `Falcon' works in read-committed transaction isolation
     level.

     *Note*:

     If the currently selected transaction isolation level is
     `read_committed' and you set the transaction isolation level to
     `serializable' when using a `Falcon' table then the transaction
     level will default to repeatable read, ignoring both the new and
     previous settings.

     The `falcon_consistent_read' variable has only local scope. You
     can set the global value, using *Note `SET GLOBAL': set-option,
     but this affects only the current local scope and all new
     connections made after the global variable was set.

   *  `falcon_debug_mask'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_debug_mask'
     Format*              
     *Config File Format* `falcon_debug_mask'
     *Option Sets         Yes, `falcon_debug_mask'
     Variable*            
     *Variable Name*      `falcon_debug_mask'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     TypeBitmap Default0  
     Valid Values1, 2,    
     4, 8, 16, 32, 64,    
     128, 256, 512        

     Sets the log information that is output to the standard output of
     *Note `mysqld': mysqld. in the event of an error. The value is a
     bit mask; you must combine values to enables different
     combinations of error message types. Formerly known as
     `falcon_log_mask'. The supported values are:

     *Version Introduced* 6.0.2
     *Command Line        `falcon_debug_mask'
     Format*              
     *Config File Format* `falcon_debug_mask'
     *Option Sets         Yes, `falcon_debug_mask'
     Variable*            
     *Variable Name*      `falcon_debug_mask'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     TypeBitmap Default0  
     Valid Values1, 2,    
     4, 8, 16, 32, 64,    
     128, 256, 512        

     Sets the log information that is output to the standard output of
     *Note `mysqld': mysqld. in the event of an error. The value is a
     bit mask; you must combine values to enables different
     combinations of error message types. Formerly known as
     `falcon_log_mask'. The supported values are:

     Value   Name          Description
     1       LogLog        Outputs minor errors, index, record and other
                           faults.
     2       LogDebug      Outputs detailed status and progress
                           information for the purposes of debugging
                           errors.
     4       LogInfo       Generates general information and status
                           messages
     8       Unused        Currently unused.
     16      Unused        Currently unused.
     32      LogGG         
     64      LogPanic      
     128     LogScrub      
     256     LogException  Logs exceptions and SQL errors.
     512     LogScavenge   Reports record scavenger statistics.

   *  `falcon_debug_server'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_debug_server'
     Format*              
     *Config File Format* `falcon_debug_server'
     *Option Sets         Yes, `falcon_debug_server'
     Variable*            
     *Variable Name*      `falcon_debug_server'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Specifies whether the debug server should be enabled.

   *  `falcon_disable_fsync'

     *Version Introduced* 6.0.2
     *Version Removed*    6.0.4
     *Command Line        `falcon_disable_fsync'
     Format*              
     *Config File Format* `falcon_disable_fsync'
     *Option Sets         Yes, `falcon_disable_fsync'
     Variable*            
     *Variable Name*      `falcon_disable_fsync'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     If true, the periodic `fsync' operation to synchronize data on
     disk is disabled. Setting this value to true may lead to data
     loss, but may increase performance.

     Default value is false (`fsync' is enabled).

   *  `falcon_gopher_threads'

     *Version Introduced* 6.0.4
     *Command Line        `falcon_gopher_threads'
     Format*              
     *Config File Format* `falcon_gopher_threads'
     *Option Sets         Yes, `falcon_gopher_threads'
     Variable*            
     *Variable Name*      `falcon_gopher_threads'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default5 Min Value1  

     Number of threads that process committed changes in the serial log
     to the database.

   *  `falcon_index_chill_threshold'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_index_chill_threshold'
     Format*              
     *Config File Format* `falcon_index_chill_threshold'
     *Option Sets         Yes, `falcon_index_chill_threshold'
     Variable*            
     *Variable Name*      `falcon_index_chill_threshold'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set (<=       
     6.0.6)*              
     Typenumeric          
     Default4 Range1-1024 
     *Value Set (>=       
     6.0.7)*              
     Typenumeric          
     Default4194304       
     Range1048576-1073741824

     The size of the pending index data that should be stored during a
     large transaction before the index changes are flushed to the
     serial log. If the index is unique, or the transaction regularly
     re-reads the index data, then the index data is stored in memory
     (for faster access). The flushing of the index data to the serial
     log is called chilling. Chilling pending indexes helps `Falcon' to
     load large data sets in a single transaction without exhausting
     memory.

     For versions up to MySQL 6.0.6, the value is specified in
     megabytes, with the minimum accepted value is 1, the maximum is
     1024 and the default value is 4.

     For versions of MySQL 6.0.7 and later, the value is specified in
     bytes, with the minimum accepted value is 1048576, the maximum is
     1073741824 and the default value is 4194304.

     This configuration option is available within *Note `mysqld':
     mysqld. as a server variable.

   *  `falcon_initial_allocation'

     *Version Introduced* 6.0.2
     *Version Removed*    6.0.6
     *Command Line        `falcon_initial_allocation'
     Format*              
     *Config File Format* `falcon_initial_allocation'
     *Option Sets         Yes, `falcon_initial_allocation'
     Variable*            
     *Variable Name*      `falcon_initial_allocation'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0 Min Value10 

     The amount of space, in MB, that should be preallocated on disk
     when a new `Falcon' tablespace file is created.

     This configuration option was removed in MySQL 6.0.6.

   *  `falcon_io_threads'

     *Version Introduced* 6.0.3
     *Command Line        `falcon_io_threads'
     Format*              
     *Config File Format* `falcon_io_threads'
     *Option Sets         Yes, `falcon_io_threads'
     Variable*            
     *Variable Name*      `falcon_io_threads'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric Default2 

     The number of asynchronous threads to be used when performing
     writes to disk.

   *  `falcon_max_transaction_backlog'

     *Version Introduced* 6.0.2
     *Version Removed*    6.0.6
     *Command Line        `falcon_max_transaction_backlog'
     Format*              
     *Config File Format* `falcon_max_transaction_backlog'
     *Option Sets         Yes, `falcon_max_transaction_backlog'
     Variable*            
     *Variable Name*      `falcon_max_transaction_backlog'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default150           

     The maximum number of pending transactions that will be active
     before the update process is blocked until the number of pending
     transactions reduces.

     This configuration option was removed in MySQL 6.0.6.

   *  `falcon_large_blob_threshold'

     *Version Introduced* 6.0.4
     *Command Line        `falcon_large_blob_threshold'
     Format*              
     *Config File Format* `falcon_large_blob_threshold'
     *Option Sets         Yes, `falcon_large_blob_threshold'
     Variable*            
     *Variable Name*      `falcon_large_blob_threshold'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          

     `BLOB' data below this threshold is stored in data pages, instead
     of `BLOB' pages. This can improve performance for smaller blobs
     because only the serial log needs to be flushed at the end of a
     transaction, and not the serial log and the blob pages.

   *  `falcon_lock_wait_timeout'

     *Version Introduced* 6.0.4
     *Command Line        `--falcon-lock-wait-timeout'
     Format*              
     *Config File Format* `falcon-lock-wait-timeout'
     *Option Sets         Yes, `falcon_lock_wait_timeout'
     Variable*            
     *Variable Name*      `falcon_lock_wait_timeout'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default50            

     The period (in seconds) that a `Falcon' transaction will wait for
     another transaction to complete when both transactions need access
     to a locked table. A value 0 indicates that `Falcon' will wait
     indefinitely for another transaction to complete.

     This variable was added in MySQL 6.0.4. (Previously, in 6.0.3,
     there was a variable named `falcon_lock_timeout' which was
     measured in milliseconds and had a default of 0.)

   *  `falcon_page_cache_size'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_page_cache_size'
     Format*              
     *Config File Format* `falcon_page_cache_size'
     *Option Sets         Yes, `falcon_page_cache_size'
     Variable*            
     *Variable Name*      `falcon_page_cache_size'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default4194304       

     Sets the amount of memory that will be allocated for caching pages
     from the tablespace file.

   *  `falcon_page_size'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_page_size'
     Format*              
     *Config File Format* `falcon_page_size'
     *Option Sets         Yes, `falcon_page_size'
     Variable*            
     *Variable Name*      `falcon_page_size'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set (<=       
     6.0.5)*              
     Typenumeric          
     Default4096 Valid    
     Values1024, 2048,    
     4096, 8192, 16384,   
     32768                
     *Value Set (>=       
     6.0.6)*              
     Typenumeric          
     Default4096 Valid    
     Values2048, 4096,    
     8192, 16384, 32768   

     Controls the size of the pages used to store information within
     the tablespace. Valid sizes are 2, 4, 8, 16 and 32 KB.

     The specified page size also affects the maximum index key lengths
     supported. The table below shows the relationship between the page
     size and the maximum index key length.

     Page Size                          Maximum Index Key Length
     2K                                 540
     4K                                 1100
     8K                                 2200
     16K                                4500
     32K                                9000

   *  `falcon_record_chill_threshold'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_record_chill_threshold'
     Format*              
     *Config File Format* `falcon_record_chill_threshold'
     *Option Sets         Yes, `falcon_record_chill_threshold'
     Variable*            
     *Variable Name*      `falcon_record_chill_threshold'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set (<=       
     6.0.6)*              
     Typenumeric          
     Default5 Range1-1024 
     *Value Set (>=       
     6.0.7)*              
     Typenumeric          
     Default5242880       
     Range1048576-1073741824

     The number of Mbytes of pending record data that `Falcon' will
     keep in memory during a large transaction before flushing these
     records to the serial log.  This flushing is called chilling since
     it makes the data not immediately available. If chilled records
     are accessed again during the transaction, they are immediately
     restored (thawed) from the serial log. Chilling pending records
     helps `Falcon' to accomplish very large transactions without
     running out of memory.

     For versions up to MySQL 6.0.6, the value is specified in
     megabytes, with the minimum accepted value is 1, the maximum is
     1024 and the default value is 5.

     For versions of MySQL 6.0.7 and later, the value is specified in
     bytes, with the minimum accepted value is 1048576, the maximum is
     1073741824 and the default value is 5242880.

   *  `falcon_record_memory_max'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_record_memory_max'
     Format*              
     *Config File Format* `falcon_record_memory_max'
     *Option Sets         Yes, `falcon_record_memory_max'
     Variable*            
     *Variable Name*      `falcon_record_memory_max'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set (<=       
     6.0.8)*              
     Typenumeric          
     Default20            
     *Value Set (>=       
     6.0.9)*              
     Typenumeric          
     Default262144000     

     Sets the maximum amount of memory that will be allocated for
     caching record data.

   *  `falcon_record_scavenge_floor'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_record_scavenge_floor'
     Format*              
     *Config File Format* `falcon_record_scavenge_floor'
     *Option Sets         Yes, `falcon_record_scavenge_floor'
     Variable*            
     *Variable Name*      `falcon_record_scavenge_floor'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default50 Range10-90 

     The percentage of `falcon_record_scavenge_threshold' that will be
     retained in the record cache after the scavenger thread has
     completed execution.

     You can determine the minimum size of the record cache using this
     formula:

          min(falcon_record_memory_max
              * (falcon_record_scavenge_threshold/100)
              * (falcon_record_scavenge_floor/100))

   *  `falcon_record_scavenge_threshold'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_record_scavenge_threshold'
     Format*              
     *Config File Format* `falcon_record_scavenge_threshold'
     *Option Sets         Yes, `falcon_record_scavenge_threshold'
     Variable*            
     *Variable Name*      `falcon_record_scavenge_threshold'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default67            
     Range10-100          

     The percentage of `falcon_record_memory_max' that will cause the
     scavenger thread to start removing old generations of records from
     the record cache.

     Default value is 67. The minimum accepted value is 10, and the
     maximum is 100.

   *  `falcon_scavenge_schedule'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_scavenge_schedule'
     Format*              
     *Config File Format* `falcon_scavenge_schedule'
     *Option Sets         Yes, `falcon_scavenge_schedule'
     Variable*            
     *Variable Name*      `falcon_scavenge_schedule'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           
     Default15,45 * * *   
     * *                  

     The record scavenging schedule, specified as a `crontab' style
     schedule. See `falcon_checkpoint_schedule'.

   *  `falcon_serial_log_buffers'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_serial_log_buffers'
     Format*              
     *Config File Format* `falcon_serial_log_buffers'
     *Option Sets         Yes, `falcon_serial_log_buffers'
     Variable*            
     *Variable Name*      `falcon_serial_log_buffers'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default10            
     Range10-1000         

     The number of memory windows allocated for the `Falcon' serial
     log. Each window is 1 MByte in size. Formerly `falcon_log_windows'.

   *  `falcon_serial_log_dir'

     *Version Introduced* 6.0.2
     *Command Line        `falcon_serial_log_dir'
     Format*              
     *Config File Format* `falcon_serial_log_dir'
     *Option Sets         Yes, `falcon_serial_log_dir'
     Variable*            
     *Variable Name*      `falcon_serial_log_dir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     Sets the directory for storing the serial log. The file names used
     by the serial log (two files are create for storing serial data)
     are allocated according to the name of the tablespace.

   *  `falcon_serial_log_priority'

     *Version Introduced* 6.0.4
     *Command Line        `falcon_serial_log_priority'
     Format*              
     *Config File Format* `falcon_serial_log_priority'
     *Option Sets         Yes, `falcon_serial_log_priority'
     Variable*            
     *Variable Name*      `falcon_serial_log_priority'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean Default1 

     Sets whether the serial log has priority other writes.

   *  `falcon_support_xa'

     *Version Introduced* 6.0.4
     *Command Line        `falcon_support_xa'
     Format*              
     *Config File Format* `falcon_support_xa'
     *Option Sets         Yes, `falcon_support_xa'
     Variable*            
     *Variable Name*      `falcon_support_xa'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeboolean          

     Specifies whether `Falcon' should support two-phase commit. When
     set to 0 (default), commits are single phase. When set to 1,
     `Falcon' reports itself as a two-phase commit supporting engine
     and supports two-phase commits.

   *  `falcon_use_deferred_index_hash'

     *Version Introduced* 6.0.4
     *Command Line        `falcon_use_deferred_index_hash'
     Format*              
     *Config File Format* `falcon_use_deferred_index_hash'
     *Option Sets         Yes, `falcon_use_deferred_index_hash'
     Variable*            
     *Variable Name*      `falcon_use_deferred_index_hash'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Enable the deferred index hash.

     Default is off

   *  `falcon_use_sectorcache'

     *Version Introduced* 6.0.6
     *Command Line        `falcon_use_sectorcache'
     Format*              
     *Config File Format* `falcon_use_sectorcache'
     *Option Sets         Yes, `falcon_use_sectorcache'
     Variable*            
     *Variable Name*      `falcon_use_sectorcache'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeboolean          
     Defaultoff           

     Use the sector cache. When enabled, disk reads are in blocks of
     64KB. When switched off, disk reads are based on the page size (as
     set by `falcon_page_size'.

     Default is off

   *  `falcon_use_supernodes'

     *Version Introduced* 6.0.5
     *Command Line        `falcon_use_supernodes'
     Format*              
     *Config File Format* `falcon_use_supernodes'
     *Option Sets         Yes, `falcon_use_supernodes'
     Variable*            
     *Variable Name*      `falcon_use_supernodes'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeboolean          
     Defaulton            

     Use supernodes within the Falcon index. Supernodes are an array of
     16 vectors into each index page to keys that are fully expanded
     with noprefix compression. This allows the page to be searched
     quicker using a binary search of supernode keys followed by the
     normal sequential search. Without enabling supernodes, the whole
     page has to be searched sequentially.

     Default is on

The relationship between the record cache and the page cache is driven
by the information that is cached by each system. Whole records that
are in active use (being read or updated) are stored within the record
cache, however, *Note `BLOB': blob. data is stored only within the page
cache.

The page cache is used to store database metadata, *Note `BLOB': blob.
data and table indexes.

`Falcon' parameters can be also be set on the command-line to *Note
`mysqld': mysqld. using the following command-line options:

   * `--falcon-max-record-memory=#'

   * `--falcon-min-record-memory=#'

   * `--falcon-page-cache-size=#'

You can also enable and disable the `Falcon' storage engine at startup
by supplying these options to *Note `mysqld': mysqld, providing that the
`mysqld' binary includes the `Falcon' Storage Engine.

   * `--falcon' enables the `Falcon' storage engine.

   * `--skip-falcon' disables the `Falcon' Storage Engine.


File: manual.info,  Node: se-falcon-createdb,  Next: se-falcon-createtable,  Prev: se-falcon-configuration,  Up: se-falcon

13.8.3 Creating the `Falcon' Tablespace
---------------------------------------

Within `Falcon', all data within one database is stored within a
tablespace file within the MySQL directory structure. By default, the
`falcon_user' tablespace file will be used for table storage,
irrespective of the table's MySQL database schema.

`Falcon' also supports named tablespaces which allow you to store
tables within specific files that may be different to the default
`Falcon' storage file for that database. Three `Falcon' tablespaces are
created automatically when the `Falcon' storage engine is enabled
within the server. These tables are:

   * An unnamed internal tablespace used to hold system tables.

   * `falcon_user', used as the default location for user defined
     tables.

   * `falcon_temporary', used to hold temporary tables.

All tablespaces share the same log files, memory and threads.
Transactions run transparently across all tablespaces. There is no
inherent relationship between a tablespace and the database/schema to
which it relates.

To create a new tablespace, use the `CREATE TABLESPACE' statement:

     CREATE TABLESPACE TABLESPACE_NAME
         ADD DATAFILE 'FILE_NAME'
         ENGINE [=] Falcon

Two further files are created by `Falcon', and these contain the
on-disk copy of the `Falcon' serial log. The log files are named
`falcon_master.fl1' and `falcon_master.fl2'.

Table definitions are, as with the other MySQL engines, stored within a
`.frm' file within a database specific directory. For example, the
table `falcontest' within the `test' database will create the table
definition file `falcontest.frm' within the directory `test'.


File: manual.info,  Node: se-falcon-createtable,  Next: se-falcon-stats,  Prev: se-falcon-createdb,  Up: se-falcon

13.8.4 Creating Tables and Indexes within `Falcon'
--------------------------------------------------

`Falcon' supports all of the standard column data types supported by
MySQL.

To create a table that uses the `Falcon' engine, employ the `ENGINE =
`Falcon'' option within the *Note `CREATE TABLE': create-table.
statement:

     CREATE TABLE names (
         id    INT,
         fname VARCHAR (20),
         lname VARCHAR (20)
     ) ENGINE=Falcon

Indexes can be created using all of the standard methods; for example
you can explicitly specify an index on a column:

     CREATE TABLE ids (
         id INT,
         INDEX (id)
     ) ENGINE=Falcon

Generate one as part of a primary key:

     CREATE TABLE ids (
         id INT,
         PRIMARY KEY (id)
     ) ENGINE=Falcon

Or you can create multi-key and multiple indexes:

     CREATE TABLE t1 (
         id   INT NOT NULL,
         id2  INT NOT NULL,
         id3  INT NOT NULL,
         name CHAR(30),
         PRIMARY KEY (id,id2),
         INDEX index_id3 (id3)
     ) ENGINE=Falcon

To create a table within a specific tablespace, add the `TABLESPACE'
definition:

     CREATE TABLE names (id INT, fname VARCHAR (20), lname VARCHAR (20))
         TABLESPACE my_big_tables ENGINE=Falcon

You can use *Note `ALTER TABLE': alter-table. to change the tablespace
for a given table; `Falcon' will move the table data to the new
tablespace:

     ALTER TABLE names TABLESPACE my_small_tables

You can drop a tablespace when it is empty (i.e. when it no longer
contains any tables) using `DROP TABLESPACE':

     DROP TABLESPACE my_big_tables ENGINE=Falcon

You cannot currently alter a tablespace (using `ALTER TABLESPACE').

*Note*:

In MySQL 6.0.3 and earlier, creating a tablespace with the same name as
another tablespace would produce an error. Also, when dropping a file
associated with a tablespace, the file itself is not physically deleted
from the file system. In either case the error returned will be: `ERROR
65433 (HY000): Unknown error -103'.

In MySQL 6.0.4 and later, the files associated with a tablespace are
deleted, and a suitable error message is returned when creating a
duplicate tablespace.


File: manual.info,  Node: se-falcon-stats,  Next: se-falcon-principles,  Prev: se-falcon-createtable,  Up: se-falcon

13.8.5 Obtaining Performance Diagnostics
----------------------------------------

`Falcon' exports internal performance diagnostic information into the
global `INFORMATION_SCHEMA' tables. Currently, `Falcon' provides
information in the following tables:

     mysql> SHOW TABLES FROM INFORMATION_SCHEMA LIKE 'falcon%';
     +----------------------------------------+
     | Tables_in_INFORMATION_SCHEMA (FALCON%) |
     +----------------------------------------+
     | FALCON_RECORD_CACHE_SUMMARY            |
     | FALCON_SYSTEM_MEMORY_DETAIL            |
     | FALCON_TABLESPACE_IO                   |
     | FALCON_SYSTEM_MEMORY_SUMMARY           |
     | FALCON_VERSION                         |
     | FALCON_TRANSACTION_SUMMARY             |
     | FALCON_SERIAL_LOG_INFO                 |
     | FALCON_SYNCOBJECTS                     |
     | FALCON_TRANSACTIONS                    |
     | FALCON_RECORD_CACHE_DETAIL             |
     +----------------------------------------+

*Note*:

The `FALCON_TABLES' and `FALCON_TABLESPACE_FILES' have been removed
from MySQL 6.0.6 and MySQL 6.0.7 respectively. From MySQL 6.0.8 the
*Note `INFORMATION_SCHEMA.TABLES': tables-table, *Note
`INFORMATION_SCHEMA.TABLESPACES': tablespaces-table. and *Note
`INFORMATION_SCHEMA.FILES': files-table. tables provide the level of
information, and are usable by other engines.

*`Falcon' `INFORMATION_SCHEMA' performance diagnostic tables*

`INFORMATION_SCHEMA'   Description
Table                  
`FALCON_SYSTEM_MEMORY_DETAIL'System memory detail; gives a detailed account of
                       the object and memory usage across the different
                       object instances of classes within `Falcon'.
`FALCON_SYSTEM_MEMORY_SUMMARY'System system memory summary; provides an
                       overview of the memory usage in `Falcon',
                       including the total memory allocated, free space
                       and fragmentation.
`FALCON_RECORD_CACHE_DETAIL'Record cache detail; shows the number of active
                       records held in the record cache and the space
                       they are currently consuming.
`FALCON_RECORD_CACHE_SUMMARY'Record cache summary shows the space allocated
                       and available for record storage, including an
                       indication of fragmentation of the record cache.
`FALCON_TRANSACTIONS'  Transactions; shows the currently active
                       transactions and their status and dependencies,
                       including the number of records affected and the
                       age of the transaction.
`FALCON_TRANSACTION_SUMMARY'Transaction summary for active transactions.
`FALCON_SYNCOBJECTS'   SyncObjects; shows detail on internal `Falcon'
                       object usage. Note that because there are a
                       separate set of synchronization objects for each
                       active database, you may get duplicate rows of
                       information in the generated table.
`FALCON_SERIAL_LOG_INFO'Serial log status information. Shows transactions
                       and serial log object usage per database. This
                       table was known as `FALCON_SERIAL_LOG' in MySQL
                       6.0.3 and earlier.
`FALCON_TABLESPACE_IO' I/O statistics showing page size, buffer size,
                       and reads/writes on a per tablespace basis.
`FALCON_VERSION'       Shows the internal `Falcon' version number and
                       release date.

The `FALCON_RECORD_CACHE_DETAIL', `FALCON_RECORD_CACHE_SUMMARY',
`FALCON_SYSTEM_MEMORY_DETAIL', and `FALCON_SYSTEM_MEMORY_SUMMARY'
tables return no information except for debug builds of MySQL. For more
information, see *Note the-dbug-package::.

The `FALCON_TABLES' table formerly listed all `Falcon' tables. This
table was removed in MySQL 6.0.7.

To obtain the diagnostic information you can run a standard *Note
`SELECT': select. statement. Depending on the `INFORMATION_SCHEMA'
table you have chosen, the information may be provided on a database or
table basis. If the information is based on a table name and that table
is stored within a unique tablespace, then the tablespace name is
quoted in the table name. For example, you can get statistics on I/O for
`Falcon' databases from the `falcon_tablespace_io' table:

     mysql> SELECT * FROM INFORMATION_SCHEMA.FALCON_TABLESPACE_IO;
     +------------------+-----------+---------+----------------+--------+---------------+-------+
     | TABLESPACE       | PAGE_SIZE | BUFFERS | PHYSICAL_READS | WRITES | LOGICAL_READS | FAKES |
     +------------------+-----------+---------+----------------+--------+---------------+-------+
     | FALCON_MASTER    |      4096 |    1024 |             59 |      0 |          1186 |     3 |
     | FALCON_TEMPORARY |      4096 |    1024 |              1 |      0 |             0 |     1 |
     | FALCON_USER      |      4096 |    1024 |              2 |      0 |             4 |     3 |
     +------------------+-----------+---------+----------------+--------+---------------+-------+

You can also `JOIN' information between tables to obtain more specific
statistics information. For example, the statement below will show the
list of statements on `Falcon' tables that are currently blocking
during transactions:

     mysql> SELECT a.id AS thread, a.user, b.id AS txn_id, b.database,
         ->        a.time, b.waiting_for, statement
         -> FROM INFORMATION_SCHEMA.PROCESSLIST a,
         ->      INFORMATION_SCHEMA.FALCON_TRANSACTIONS b
         -> WHERE a.id = b.thread_id;
     +--------+------+--------+----------+------+-------------+--------------------------------+
     | thread | user | txn_id | database | time | waiting_for | statement                      |
     +--------+------+--------+----------+------+-------------+--------------------------------+
     |      2 | root |      8 | GIMF     |    0 |           0 |                                |
     |      3 | root |      9 | GIMF     |   76 |           8 | update rms set c1=5 where c1=1 |
     +--------+------+--------+----------+------+-------------+--------------------------------+


File: manual.info,  Node: se-falcon-principles,  Next: se-falcon-limits,  Prev: se-falcon-stats,  Up: se-falcon

13.8.6 Principles and Terminology
---------------------------------

* Menu:

* se-falcon-principles-tablespace::  `Falcon' data file and data structures
* se-falcon-principles-logging::  `Falcon' Serial Log
* se-falcon-principles-recovery::  `Falcon' Crash Recovery
* se-falcon-principles-caches::  `Falcon' Memory Caches
* se-falcon-principles-threads::  `Falcon' Threads
* se-falcon-principles-compression::  Data Compression
* se-falcon-principles-recordslot::  Record Slot

To get the best out of the `Falcon' engine you should understand the
following basic principles and terminology.

The MySQL `Falcon' architecture combines advanced techniques with a
simplified structure that results in a high-performance transactional
database that requires little maintenance or troubleshooting by the
database administrator.

   * *User data file* -- stores the `Falcon' data.

   * *`Falcon' serial log* -- contains recently committed data changes,
     index changes and transactional information. Also provides data
     recovery facilities.

   * *Page cache* -- holds database pages being read or written.

   * *Record cache* -- holds copies of active and uncommitted records.

   * *System memory* -- contains transaction context information, index
     accelerators and system metadata.

   * *Work Threads* -- are background threads. There are two threads,
     the "gopher" thread moves data from the `Falcon' Serial Log into
     the database page cache and from the page cache to disk. The
     second is the page writer thread which writes blob pages.


File: manual.info,  Node: se-falcon-principles-tablespace,  Next: se-falcon-principles-logging,  Prev: se-falcon-principles,  Up: se-falcon-principles

13.8.6.1 `Falcon' data file and data structures
...............................................

A single `Falcon' database file stores all record data, indexes,
database structure and other information.  The individual information
is stored within a series of pages.

Pages describe the internal storage allocation block within the
`Falcon' storage engine. Pages are used to store data and index
information. The page size and how the `Falcon' engine caches and
allocates pages for use when storing information affect the performance
of the engine depending on the records that are being stored, index
complexity

Pages cached in memory are used to store indexes, blobs and the
structural data for a given tablespace. Active records (those read or
updated are stored within a separate record cache.

All transactions on the database are logged and stored within a
separate log file. The log file is automatically flushed and the
changes written to disk when there is a *Note `COMMIT': commit.
command, when auto-commit is enabled, or automatically every 30 seconds
when transactions are not being employed.


File: manual.info,  Node: se-falcon-principles-logging,  Next: se-falcon-principles-recovery,  Prev: se-falcon-principles-tablespace,  Up: se-falcon-principles

13.8.6.2 `Falcon' Serial Log
............................

* Menu:

* se-falcon-principles-logging-rollback::  Rollback Process
* se-falcon-principles-logging-groupcommit::  Group Commits

`Falcon' uses a Serial Log to hold certain types of information before
that data is finally committed to the database. The log is used to
store the following types of information:

   * Data records during the commit phase.

   * Physical database changes required for data recovery after a crash.

   * Logical database changes required for resource recovery after a
     crash.

   * Transaction state changes for all active transactions (active to
     committed, active to rolled back, active to limbo).

All transactions within `Falcon' are written to the `Falcon' Serial Log
and then committed to the database, either automatically when
`autocommit' is enabled, or manually when the *Note `COMMIT': commit.
command is used.

Logging information is stored in memory and unwritten changes to the
log are periodically flushed to disk. A background thread processes the
contents of the log, committing the log changes to the database. The
commit process sets the final status of all records and pages,
regardless of any intervening states; only the final state is actually
written to disk.

Note, however, that the serial log commit process only updates the
record data through the in-memory page cache. The actual record data
will be written to disk when the checkpoint process occurs. The
exception to this rule are index and log entries, which are immediately
written to disk as part of the commit process.

`Falcon' creates two serial log files. The first log file is used to
store the serial log data until the log reaches a specified size. Once
that size has been reached, logging is switched to the second serial
log file. The commit process continues to read from the first log file
until all transactions have been written to the database. The first log
file is then released and recreated.

Log entries in the second file are then processed until all
transactions in the log have been completed. That file is then released
and recreated, ready to be pressed into use as soon as the first log
file is full or becomes locked for commits.


File: manual.info,  Node: se-falcon-principles-logging-rollback,  Next: se-falcon-principles-logging-groupcommit,  Prev: se-falcon-principles-logging,  Up: se-falcon-principles-logging

13.8.6.3 Rollback Process
.........................

Transaction rollbacks are handled by the thread for that transaction.
The rollback process performs the following actions:

   * Backing out index updates.

   * Backing out any blob data created by the transaction.

   * Releasing allocated record slots.

   * Backing out record versions created in memory.


File: manual.info,  Node: se-falcon-principles-logging-groupcommit,  Prev: se-falcon-principles-logging-rollback,  Up: se-falcon-principles-logging

13.8.6.4 Group Commits
......................

For performance, `Falcon' uses a group commit system that ensures that
all pending updates to the serial log are written to disk at the same
time.  `Falcon' can have multiple active transactions, but only one
transactions writes all the pending changes into the serial log on
disk, reducing the number of disk writes and improving the overall
performance of the serial log.

For example:

  1. Transaction 1 commits, creates all the necessary log entries, and
     starts to write the log to disk.

  2. While Transaction 1 commits are being written, Transactions 2 and
     3 write their log entries into the serial log.

  3. Once Transaction 1 has finished the physical write, either
     transaction 2 or 3 (but not both) will write out the unwritten
     portion of the in-memory log to disk. Because both transactions
     have occurred since the last disk-write of the serial log, the
     information for both is written to the disk at the same time.

  4. While transactions 2 and 3 are writing, transactions 4, 5 and 6
     are being written to the in-memory log. When the write for 2 and 3
     completes, the entries for 4, 5 and 6 are written.

The result of the above process is that there are only three physical
writes to disk, even though there are six transactions in the sequence:

   * Transaction 1

   * Transactions 2 and 3

   * Transactions 4, 5 and 6

The process continues, with just one transaction writing all the
in-memory serial log entries to disk since the last write.  The entire
system ensures that the in-memory and disk logs are kept in
synchronization, with the fewest possible physical disk writes.


File: manual.info,  Node: se-falcon-principles-recovery,  Next: se-falcon-principles-caches,  Prev: se-falcon-principles-logging,  Up: se-falcon-principles

13.8.6.5 `Falcon' Crash Recovery
................................

The `Falcon' Serial Log is examined when the first table in a `Falcon'
database is opened.  If the state of the log indicates that there are
uncommitted transactions, the recovery process starts automatically and
updates the database. When transactions and changes are written to the
Serial Log the log includes entries that record changes to all areas of
the database, including the indexes, changes to *Note `BLOB': blob.
data, and any structural changes to the database.

During crash recovery, `Falcon' examines the serial log and identifies
the first entry that has not been committed to the database. The
recovery process writes all unwritten data, changes index and blob
data, releases any necessary record slots (from deleted records) and
commits any structural changes.


File: manual.info,  Node: se-falcon-principles-caches,  Next: se-falcon-principles-threads,  Prev: se-falcon-principles-recovery,  Up: se-falcon-principles

13.8.6.6 `Falcon' Memory Caches
...............................

`Falcon' was designed to perform best on systems with generous amounts
of memory. The memory caches utilized by `Falcon' are similar in some
respects with other RDBMS's and MySQL engines; however, the cache
structures offer a number of improvements over traditional memory
caching strategies. The mechanisms used by `Falcon' with respect to
memory caching include:

   * *Log Cache* -- log information is kept in memory and flushed to the
     `Falcon' Log when transactions commit.  `Falcon' keeps eight 1 MB
     windows into the log file for reading and writing.

   * *System and Index Cache* -- data needed by `Falcon' (table and
     field definitions, transaction state, etc.) is also maintained in
     memory for quick reference. In addition, local index accelerators
     represent index segments created by a running transaction are also
     stored in the system memory.  When a transaction changes indexed
     fields, it builds an index accelerator section in system memory,
     representing its changes. On commit, all index changes for the
     transaction are written to the serial log in sorted order and later
     merged with the permanent index by the worker thread.

   * *Page Cache* -- database pages read from disk for a particular
     database. The page cache size is controlled by the
     `falcon_page_cache_size' parameter, which defaults to 4MB, and is
     set in the my.cnf file. Although record and index changes go to
     the serial log before being written to database pages, blob data
     is written directly into the page cache. This avoids logging large
     data items that are rarely referenced or changed by the
     transaction that creates them.

   * *Record Cache* -- the record cache is a memory region devoted to
     holding rows that have been requested by end-user queries for a
     particular database or created by active transactions. Note that
     this cache differs from traditional data caches in that only
     specific rows needed by applications reside in the cache as
     opposed to entire data pages (which may contain only subsets of
     needed information). The record cache can hold several versions of
     records that have been modified or deleted. This technique
     guarantees that active data needed to satisfy user requests is in
     memory, shortens row access time, and reduces cache bloat by not
     including unrequested information. The record cache also assists
     in supporting the multi-version concurrency control (MVCC)
     mechanisms of the `Falcon' engine. The record cache is controlled
     by two parameters. The `falcon_min_record_memory' parameter
     (default 10MB) determines the minimum amount of RAM supplied to
     the record cache and the `falcon_max_record_memory' (default 20MB)
     limits the total amount of memory available to the cache.

   * Because of the support the record cache supplies to transactions,
     a scavenge thread is used to ensure only "hot" data resides in the
     cache. When the `falcon_max_record_memory' limit is reached,
     `Falcon' surveys the demographics of the generational data in the
     cache, and removes the oldest generations. This process is more
     complicated than the standard LRU algorithm used by many database
     systems, but it is more efficient and faster.


File: manual.info,  Node: se-falcon-principles-threads,  Next: se-falcon-principles-compression,  Prev: se-falcon-principles-caches,  Up: se-falcon-principles

13.8.6.7 `Falcon' Threads
.........................

`Falcon' uses two worker threads to process information within the
`Falcon' structures. One thread, the "gopher" thread, is devoted to
moving committed data changes from the `Falcon' log to data pages and
to merge index changes with permanent index data. The second thread
handles the periodic flushing of the page cache and scavenges space
allocated within the record cache.


File: manual.info,  Node: se-falcon-principles-compression,  Next: se-falcon-principles-recordslot,  Prev: se-falcon-principles-threads,  Up: se-falcon-principles

13.8.6.8 Data Compression
.........................

Data stored in the `Falcon' tablespace is compressed on disk, but is
stored in an uncompressed format in memory. Compression occurs
automatically when data is committed to disk.


File: manual.info,  Node: se-falcon-principles-recordslot,  Prev: se-falcon-principles-compression,  Up: se-falcon-principles

13.8.6.9 Record Slot
....................

A record slot is an internal record identifier that is used to find
records in memory and on disk. It is essentially a pointer to the pages
that contain the data for a particular record. A new record slot is
created for each record for the duration of that record's existence.
The record slot is only relinquished when the record is erased from the
database.


File: manual.info,  Node: se-falcon-limits,  Next: se-falcon-roadmap,  Prev: se-falcon-principles,  Up: se-falcon

13.8.7 Notes and Limits
-----------------------

You should be aware of the following points when using the `Falcon'
storage engine:

   * When creating a table using `AUTO_INCREMENT' within `Falcon' you
     should be aware that `Falcon' uses a persistent auto increment
     counter. Generated values will never be reused, even when the
     MySQL server is restarted after rolling back a transaction that
     allocated auto increment values.

   * When creating temporary tables within `Falcon', the tables are
     automatically created in the `FALCON_TEMPORARY' tablespace.  If
     you specify an alternate tablespace to the *Note `CREATE TABLE':
     create-table. statement then a warning will be issued.

   * `Falcon' uses sequences when creating values in tables with an
     `AUTO_INCREMENT' column.  Once a sequence has been created, the
     auto-increment value has already been allocated, even if the
     transaction is rolled back. This means that the information report
     by *Note `SHOW TABLE STATUS': show-table-status. about the next
     auto-increment value in the table is correct, but may be different
     from what you expect compared to the behavior of `InnoDB' tables.

   * During a transaction, the count of the number of records within a
     `Falcon' table shown by *Note `SHOW TABLE STATUS':
     show-table-status. reflects the number of rows in the table before
     the transaction was started. Because of this, the value is
     consistent even if the user later roll back the transaction. The
     information is only updated when the records are finally committed
     to the table.

     If the table is empty, then the row count shown by *Note `SHOW
     TABLE STATUS': show-table-status. will be 2.  During a transaction
     where new rows written into a table with an `AUTO_INCREMENT'
     column, the row count will continue to register the lower value,
     even though the `next_increment' value will show the correct value
     and show that rows have been inserted into the table.  This is
     because `Falcon' uses sequences that allocate the increment value,
     and increment values are never re-used, even if the transactions
     are rolled back.

     This behaviour is different to both `MyISAM' and `InnoDB' behavior
     when comparing the output of *Note `SHOW TABLE STATUS':
     show-table-status. and auto incremented values.

There are a number of limits in the alpha release of `Falcon'; these
will be addressed in forthcoming releases:

   * Starting with MySQL 6.0.4, `Falcon' will reject tables where an
     `AUTO_INCREMENT' column has been declared as part of a
     multi-column index but is not the first column in the index. This
     mirrors the behaviour of InnoDB, but is incompatible with the
     support provided in MyISAM for such tables. For more information on
     this behavior, see *Note example-auto-increment::.

   * Starting with MySQL 6.0.6, Falcon provides Page checksum
     protection.

   * Falcon does not currently support live downgrades due to the
     changes in the structure of the serial log and tablespace
     structures. For example, you cannot downgrade from MySQL 6.0.5 to
     MySQL 6.0.4. If you need to downgrade your current installation to
     an earlier version, you must dump your database using *Note
     `mysqldump': mysqldump, downgrade, and then re-import the dumped
     database.

   * `Falcon' behaves as if the `lower_case_table_names' option has
     been enabled irrespective of the current platform.

   * There is a limit of 2^32 (4.29 billion) rows for a single table.
     By using multiple tables within the same tablespace you can have
     more than this number of records. In future releases this limit
     will be removed.

   * Each tablespace has a limit of 2^32 pages within a single
     tablespace. Through a combination of the page size and the maximum
     number of pages in a tablespace, there is a limit of
     140,737,488,355,328 bytes (128 TB) to a single tablespace.

   * Online backup is not supported, but support is planned in a future
     release.

   * Foreign key support is currently not available.

   * Falcon does not support statement-based logging and replication.
     If you have set `--binlog-format=STATEMENT', or
     `--binlog-format=MIXED' then logging for Falcon tables will
     automatically use `ROW' based logging, irrespective of those
     settings.

   * Although the maximum available storage within a tablespace is
     128TB, the true number of records and quantity of data that you
     can store is dependent on a number of factors:

        * Record storage requirements

        * Index storage requirements

        * Compression ratio of stored data

     Because of the complex relationship between the storage, indexing
     and compression facilities it is impossible to predict or
     calculate the disk storage space required for a specific data set.


File: manual.info,  Node: se-falcon-roadmap,  Prev: se-falcon-limits,  Up: se-falcon

13.8.8 `Falcon' Roadmap
-----------------------

The following features will be added to `Falcon' before it reaches GA
(General Availability). This section is subject to change as long as
MySQL `Falcon' development is in its early stages.

   * XA Transactions including durable two phase commit

   * On-line index add and drop

   * Log file truncation


File: manual.info,  Node: merge-storage-engine,  Next: memory-storage-engine,  Prev: se-falcon,  Up: storage-engines

13.9 The `MERGE' Storage Engine
===============================

* Menu:

* merge-table-problems::         `MERGE' Table Problems

The `MERGE' storage engine, also known as the `MRG_MyISAM' engine, is a
collection of identical `MyISAM' tables that can be used as one.
`Identical' means that all tables have identical column and index
information. You cannot merge `MyISAM' tables in which the columns are
listed in a different order, do not have exactly the same columns, or
have the indexes in different order. However, any or all of the
`MyISAM' tables can be compressed with *Note `myisampack': myisampack.
See *Note myisampack::. Differences in table options such as
`AVG_ROW_LENGTH', `MAX_ROWS', or `PACK_KEYS' do not matter.

When you create a `MERGE' table, MySQL creates two files on disk. The
files have names that begin with the table name and have an extension
to indicate the file type. An `.frm' file stores the table format, and
an `.MRG' file contains the names of the tables that should be used as
one. The tables do not have to be in the same database as the `MERGE'
table itself.

You can use *Note `SELECT': select, *Note `DELETE': delete, *Note
`UPDATE': update, and *Note `INSERT': insert. on `MERGE' tables. You
must have `SELECT', `UPDATE', and `DELETE' privileges on the `MyISAM'
tables that you map to a `MERGE' table.

*Note*:

The use of `MERGE' tables entails the following security issue: If a
user has access to `MyISAM' table T, that user can create a `MERGE'
table M that accesses T. However, if the user's privileges on T are
subsequently revoked, the user can continue to access T by doing so
through M.

If you `DROP' the `MERGE' table, you are dropping only the `MERGE'
specification.  The underlying tables are not affected.

To create a `MERGE' table, you must specify a `UNION=(LIST-OF-TABLES)'
clause that indicates which `MyISAM' tables you want to use as one. You
can optionally specify an `INSERT_METHOD' option if you want inserts
for the `MERGE' table to take place in the first or last table of the
*Note `UNION': union. list. Use a value of `FIRST' or `LAST' to cause
inserts to be made in the first or last table, respectively. If you do
not specify an `INSERT_METHOD' option or if you specify it with a value
of `NO', attempts to insert rows into the `MERGE' table result in an
error.

The following example shows how to create a `MERGE' table:

     mysql> CREATE TABLE t1 (
         ->    a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
         ->    message CHAR(20)) ENGINE=MyISAM;
     mysql> CREATE TABLE t2 (
         ->    a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
         ->    message CHAR(20)) ENGINE=MyISAM;
     mysql> INSERT INTO t1 (message) VALUES ('Testing'),('table'),('t1');
     mysql> INSERT INTO t2 (message) VALUES ('Testing'),('table'),('t2');
     mysql> CREATE TABLE total (
         ->    a INT NOT NULL AUTO_INCREMENT,
         ->    message CHAR(20), INDEX(a))
         ->    ENGINE=MERGE UNION=(t1,t2) INSERT_METHOD=LAST;

Note that the `a' column is indexed as a `PRIMARY KEY' in the underlying
`MyISAM' tables, but not in the `MERGE' table. There it is indexed but
not as a `PRIMARY KEY' because a `MERGE' table cannot enforce
uniqueness over the set of underlying tables.

When a table that is part of a `MERGE' table is opened, the following
checks are applied before opening each table.  If any table fails the
conformance checks, then the operation that triggered the opening of
the table will fail. The conformance checks applied to each table are:

   * Table must have exactly the same amount of columns that `MERGE'
     table has.

   * Column order in the `MERGE' table must match the column order in
     the underlying tables.

   * Additionally, the specification for each column in the parent
     `MERGE' table and the underlying table are compared. For each
     column, MySQL checks:

        * Column type in the underlying table equals the column type of
          `MERGE' table.

        * Column length in the underlying table equals the column
          length of `MERGE' table.

        * Column of underlying table and column of `MERGE' table can be
          `NULL'.

   * Underlying table must have at least the same amount of keys that
     merge table has. The underlying table may have more keys than the
     `MERGE' table, but cannot have less.

     *Note*:

     A known issue exists that keys on the some columns must be
     identical in order in both the `MERGE' table and the underlying
     `MyISAM' table. See Bug#33653 (http://bugs.mysql.com/33653).

     For each key:

        * Check if the key type of underlying table equals the key type
          of merge table.

        * Check if number of key parts (i.e. multiple columns within a
          compound key) in the underlying table key definition equals
          the number of key parts in merge table key definition.

        * For each key part:

             * Check if key part lengths are equal.

             * Check if key part types are equal.

             * Check if key part languages are equal.

             * Check if key part can be `NULL'.

After creating the `MERGE' table, you can issue queries that operate on
the group of tables as a whole:

     mysql> SELECT * FROM total;
     +---+---------+
     | a | message |
     +---+---------+
     | 1 | Testing |
     | 2 | table   |
     | 3 | t1      |
     | 1 | Testing |
     | 2 | table   |
     | 3 | t2      |
     +---+---------+

To remap a `MERGE' table to a different collection of `MyISAM' tables,
you can use one of the following methods:

   * `DROP' the `MERGE' table and re-create it.

   * Use `ALTER TABLE TBL_NAME UNION=(...)' to change the list of
     underlying tables.

     Beginning with MySQL 6.0.5, it is also possible to use `ALTER
     TABLE ... UNION=()' (that is, with an empty *Note `UNION': union.
     clause) to remove all of the underlying tables. (Bug#28248
     (http://bugs.mysql.com/28248))

`MERGE' tables can help you solve the following problems:

   * Easily manage a set of log tables. For example, you can put data
     from different months into separate tables, compress some of them
     with *Note `myisampack': myisampack, and then create a `MERGE'
     table to use them as one.

   * Obtain more speed. You can split a big read-only table based on
     some criteria, and then put individual tables on different disks.
     A `MERGE' table on this could be much faster than using the big
     table.

   * Perform more efficient searches. If you know exactly what you are
     looking for, you can search in just one of the split tables for
     some queries and use a `MERGE' table for others. You can even have
     many different `MERGE' tables that use overlapping sets of tables.

   * Perform more efficient repairs. It is easier to repair individual
     tables that are mapped to a `MERGE' table than to repair a single
     large table.

   * Instantly map many tables as one. A `MERGE' table need not
     maintain an index of its own because it uses the indexes of the
     individual tables. As a result, `MERGE' table collections are
     _very_ fast to create or remap. (Note that you must still specify
     the index definitions when you create a `MERGE' table, even though
     no indexes are created.)

   * If you have a set of tables from which you create a large table on
     demand, you should instead create a `MERGE' table on them on
     demand. This is much faster and saves a lot of disk space.

   * Exceed the file size limit for the operating system. Each `MyISAM'
     table is bound by this limit, but a collection of `MyISAM' tables
     is not.

   * You can create an alias or synonym for a `MyISAM' table by
     defining a `MERGE' table that maps to that single table.  There
     should be no really notable performance impact from doing this
     (only a couple of indirect calls and `memcpy()' calls for each
     read).

The disadvantages of `MERGE' tables are:

   * You can use only identical `MyISAM' tables for a `MERGE' table.

   * You cannot use a number of `MyISAM' features in `MERGE' tables.
     For example, you cannot create `FULLTEXT' indexes on `MERGE'
     tables. (You can, of course, create `FULLTEXT' indexes on the
     underlying `MyISAM' tables, but you cannot search the `MERGE'
     table with a full-text search.)

   * If the `MERGE' table is non-temporary, all underlying `MyISAM'
     tables must be non-temporary, too. If the `MERGE' table is
     temporary, the `MyISAM' tables can be any mix of temporary and
     non-temporary.

   * `MERGE' tables use more file descriptors. If 10 clients are using
     a `MERGE' table that maps to 10 tables, the server uses (10 x 10)
     + 10 file descriptors. (10 data file descriptors for each of the 10
     clients, and 10 index file descriptors shared among the clients.)

   * Key reads are slower. When you read a key, the `MERGE' storage
     engine needs to issue a read on all underlying tables to check
     which one most closely matches the given key. To read the next
     key, the `MERGE' storage engine needs to search the read buffers
     to find the next key. Only when one key buffer is used up does the
     storage engine need to read the next key block. This makes `MERGE'
     keys much slower on `eq_ref' searches, but not much slower on
     `ref' searches. See *Note explain::, for more information about
     `eq_ref' and `ref'.

*Additional resources*

   * A forum dedicated to the `MERGE' storage engine is available at
     `http://forums.mysql.com/list.php?93'.


File: manual.info,  Node: merge-table-problems,  Prev: merge-storage-engine,  Up: merge-storage-engine

13.9.1 `MERGE' Table Problems
-----------------------------

The following are known problems with `MERGE' tables:

   * If you use *Note `ALTER TABLE': alter-table. to change a `MERGE'
     table to another storage engine, the mapping to the underlying
     tables is lost. Instead, the rows from the underlying `MyISAM'
     tables are copied into the altered table, which then uses the
     specified storage engine.

   * *Note `REPLACE': replace. does not work as expected because the
     `MERGE' engine cannot enforce uniqueness over the set of
     underlying tables. The two key facts are:

        * *Note `REPLACE': replace. can detect unique key violations
          only in the underlying table to which it is going to write
          (which is determined by `INSERT_METHOD'). This differs from
          violations in the `MERGE' table itself.

        * If *Note `REPLACE': replace. detects such a violation, it
          will only change the corresponding row in the first
          underlying table in which the row is present, whereas a row
          with the same unique key value may be present in all
          underlying tables.

     Similar considerations apply for `INSERT ... ON DUPLICATE KEY
     UPDATE'.

   * `MERGE' tables do not support partitioning.  That is, you cannot
     partition a `MERGE' table, nor can any of a `MERGE' table's
     underlying `MyISAM' tables be partitioned.

   * You cannot use *Note `REPAIR TABLE': repair-table, *Note `OPTIMIZE
     TABLE': optimize-table, *Note `DROP TABLE': drop-table, *Note
     `ALTER TABLE': alter-table, *Note `DELETE': delete. without a
     `WHERE' clause, *Note `TRUNCATE TABLE': truncate, or *Note
     `ANALYZE TABLE': analyze-table. on any of the tables that are
     mapped into an open `MERGE' table. If you do so, the `MERGE' table
     may still refer to the original table, which yields unexpected
     results. The easiest way to work around this deficiency is to
     ensure that no `MERGE' tables remain open by issuing a *Note
     `FLUSH TABLES': flush.  statement prior to performing any of those
     operations.

     The unexpected results include the possibility that the operation
     on the `MERGE' table will report table corruption. However, if
     this occurs after operations on the underlying `MyISAM' tables
     such as those listed in the previous paragraph (*Note `REPAIR
     TABLE': repair-table, *Note `OPTIMIZE TABLE': optimize-table, and
     so forth), the corruption message is spurious. To deal with this,
     issue a *Note `FLUSH TABLES': flush.  statement after modifying
     the `MyISAM' tables.

   * *Note `DROP TABLE': drop-table. on a table that is in use by a
     `MERGE' table does not work on Windows because the `MERGE' storage
     engine's table mapping is hidden from the upper layer of MySQL.
     Windows does not allow open files to be deleted, so you first must
     flush all `MERGE' tables (with *Note `FLUSH TABLES': flush.)  or
     drop the `MERGE' table before dropping the table.

   * A `MERGE' table cannot maintain uniqueness constraints over the
     entire table. When you perform an *Note `INSERT': insert, the data
     goes into the first or last `MyISAM' table (depending on the value
     of the `INSERT_METHOD' option).  MySQL ensures that unique key
     values remain unique within that `MyISAM' table, but not across
     all the tables in the collection.

   * The `INSERT_METHOD' table option for a `MERGE' table indicates
     which underlying `MyISAM' table to use for inserts into the
     `MERGE' table. However, use of the `AUTO_INCREMENT' table option
     for that `MyISAM' table has no effect for inserts into the `MERGE'
     table until at least one row has been inserted directly into the
     `MyISAM' table.

   * The definition of the `MyISAM' tables and the `MERGE' table are
     checked when the tables are accessed (for example, as part of a
     *Note `SELECT': select. or *Note `INSERT': insert. statement). The
     checks ensure that the definitions of the tables and the parent
     `MERGE' table definition match by comparing column order, types,
     sizes and associated indexes. If there is a difference between the
     tables then an error will be returned and the statement will fail.

     Because these checks take place when the tables are opened, any
     changes to the definition of a single table, including column
     changes, column ordering and engine alterations will cause the
     statement to fail.

   * The order of indexes in the `MERGE' table and its underlying
     tables should be the same. If you use *Note `ALTER TABLE':
     alter-table. to add a `UNIQUE' index to a table used in a `MERGE'
     table, and then use *Note `ALTER TABLE': alter-table. to add a
     non-unique index on the `MERGE' table, the index ordering is
     different for the tables if there was already a non-unique index
     in the underlying table. (This happens because *Note `ALTER
     TABLE': alter-table. puts `UNIQUE' indexes before non-unique
     indexes to facilitate rapid detection of duplicate keys.)
     Consequently, queries on tables with such indexes may return
     unexpected results.

   * If you encounter an error message similar to `ERROR 1017 (HY000):
     Can't find file: 'MM.MRG' (errno: 2)' it generally indicates that
     some of the base tables are not using the `MyISAM' storage engine.
     Confirm that all of these tables are `MyISAM'.

   * The maximum number of rows in a `MERGE' table is 2^64 (~1.844E+19;
     the same as for a `MyISAM' table), provided that the server was
     built using the `--with-big-tables' option.  (All standard MySQL
     6.0 standard binaries are built with this option; for more
     information, see *Note configure-options::.) It is not possible to
     merge multiple `MyISAM' tables into a single `MERGE' table that
     would have more than this number of rows.

   * The `MERGE' storage engine does not support *Note `INSERT
     DELAYED': insert-delayed. statements.

   * Using different underlying row formats in `MyISAM' tables with a
     parent `MERGE' table is currently known to fail. See Bug#32364
     (http://bugs.mysql.com/32364).

   * Starting with MySQL 6.0.4, you cannot change the union list of a
     non-temporary `MERGE' table when LOCK TABLES is in effect. The
     following does _not_ work:

          CREATE TABLE m1 ... ENGINE=MRG_MYISAM ...;
                    LOCK TABLES t1 WRITE, t2 WRITE, m1 WRITE;
                    ALTER TABLE m1 ... UNION=(t1,t2) ...;

     However, you can do this with a temporary `MERGE' table.

   * Starting with MySQL 6.0.4, you cannot create a `MERGE' table with
     `CREATE ...  SELECT', neither as a temporary `MERGE' table, nor as
     a non-temporary `MERGE' table. For example:

          CREATE TABLE m1 ... ENGINE=MRG_MYISAM ... SELECT ...;

     Gives error message: table is not `BASE TABLE'.


File: manual.info,  Node: memory-storage-engine,  Next: example-storage-engine,  Prev: merge-storage-engine,  Up: storage-engines

13.10 The `MEMORY' (`HEAP') Storage Engine
==========================================

The `MEMORY' storage engine creates tables with contents that are
stored in memory. Formerly, these were known as `HEAP' tables. `MEMORY'
is the preferred term, although `HEAP' remains supported for backward
compatibility.

*Memory Features*

*Storage limits* RAM      *Transactions*   No       *Locking         Table
                                                    granularity*     
*MVCC*           No       *Geospatial      No       *Geospatial      No
                          datatype                  indexing         
                          support*                  support*         
*B-tree indexes* Yes      *Hash indexes*   Yes      *Full-text       No
                                                    search indexes*  
*Clustered       No       *Data caches*    N/A      *Index caches*   N/A
indexes*                                                             
*Compressed      No       *Encrypted data  Yes      *Cluster         No
data*                     Implemented in            database         
                          the server (via           support*         
                          encryption                                 
                          functions),                                
                          rather than in                             
                          the storage                                
                          engine.*                                   
*Replication     Yes      *Foreign key     No       *Backup /        Yes
support                   support*                  point-in-time    
Implemented in                                      recovery         
the server,                                         Implemented in   
rather than in                                      the server,      
the storage                                         rather than in   
engine*                                             the storage      
                                                    engine*          
*Query cache     Yes      *Update          Yes                       
support*                  statistics for                             
                          data dictionary*                           

Each `MEMORY' table is associated with one disk file. The file name
begins with the table name and has an extension of `.frm' to indicate
that it stores the table definition.

To specify explicitly that you want to create a `MEMORY' table,
indicate that with an `ENGINE' table option:

     CREATE TABLE t (i INT) ENGINE = MEMORY;

As indicated by the name, `MEMORY' tables are stored in memory. They
use hash indexes by default, which makes them very fast, and very
useful for creating temporary tables. However, when the server shuts
down, all rows stored in `MEMORY' tables are lost. The tables themselves
continue to exist because their definitions are stored in `.frm' files
on disk, but they are empty when the server restarts.

This example shows how you might create, use, and remove a `MEMORY'
table:

     mysql> CREATE TABLE test ENGINE=MEMORY
         ->     SELECT ip,SUM(downloads) AS down
         ->     FROM log_table GROUP BY ip;
     mysql> SELECT COUNT(ip),AVG(down) FROM test;
     mysql> DROP TABLE test;

`MEMORY' tables have the following characteristics:

   * Space for `MEMORY' tables is allocated in small blocks. Tables use
     100% dynamic hashing for inserts. No overflow area or extra key
     space is needed. No extra space is needed for free lists. Deleted
     rows are put in a linked list and are reused when you insert new
     data into the table.  `MEMORY' tables also have none of the
     problems commonly associated with deletes plus inserts in hashed
     tables.

   * `MEMORY' tables can have up to 32 indexes per table, 16 columns
     per index and a maximum key length of 500 bytes.

   * The `MEMORY' storage engine implements both `HASH' and `BTREE'
     indexes.  You can specify one or the other for a given index by
     adding a `USING' clause as shown here:

          CREATE TABLE lookup
              (id INT, INDEX USING HASH (id))
              ENGINE = MEMORY;
          CREATE TABLE lookup
              (id INT, INDEX USING BTREE (id))
              ENGINE = MEMORY;

     General characteristics of B-tree and hash indexes are described
     in *Note mysql-indexes::.

   * You can have non-unique keys in a `MEMORY' table. (This is an
     uncommon feature for implementations of hash indexes.)

   * If you have a hash index on a `MEMORY' table that has a high
     degree of key duplication (many index entries containing the same
     value), updates to the table that affect key values and all
     deletes are significantly slower. The degree of this slowdown is
     proportional to the degree of duplication (or, inversely
     proportional to the index cardinality). You can use a `BTREE'
     index to avoid this problem.

   * Columns that are indexed can contain `NULL' values.

   * `MEMORY' tables use a fixed-length row storage format.

   * `MEMORY' tables cannot contain *Note `BLOB': blob. or *Note
     `TEXT': blob. columns.

   * `MEMORY' includes support for `AUTO_INCREMENT' columns.

   * You can use *Note `INSERT DELAYED': insert-delayed. with `MEMORY'
     tables. See *Note insert-delayed::.

   * `MEMORY' tables are shared among all clients (just like any other
     non-`TEMPORARY' table).

   * `MEMORY' table contents are stored in memory, which is a property
     that `MEMORY' tables share with internal tables that the server
     creates on the fly while processing queries. However, the two
     types of tables differ in that `MEMORY' tables are not subject to
     storage conversion, whereas internal tables are:

        * If an internal table becomes too large, the server
          automatically converts it to an on-disk table. The size limit
          is determined by the value of the `tmp_table_size' system
          variable.

        * `MEMORY' tables are never converted to disk tables.

        * The maximum size of `MEMORY' tables is limited by the
          `max_heap_table_size' system variable, which has a default
          value of 16MB. To have larger (or smaller) `MEMORY' tables,
          you must change the value of this variable. The value in
          effect at the time a `MEMORY' table is created is the value
          used for the life of the table. (If you use *Note `ALTER
          TABLE': alter-table. or *Note `TRUNCATE TABLE': truncate, the
          value in effect at that time becomes the new maximum size for
          the table. A server restart also sets the maximum size of
          existing `MEMORY' tables to the global `max_heap_table_size'
          value.)  You can set the size for individual tables as
          described later in this section.

   * The server needs sufficient memory to maintain all `MEMORY' tables
     that are in use at the same time.

   * Memory used by a `MEMORY' table is not reclaimed if you delete
     individual rows from the table. Memory is only reclaimed when the
     entire table is deleted. Memory that was previously used for rows
     that have been deleted will be re-used for new rows only within
     the same table. To free up the memory used by rows that have been
     deleted you should use `ALTER TABLE ENGINE=MEMORY' to force a table
     rebuild.

     To free all the memory used by a `MEMORY' table when you no longer
     require its contents, you should execute *Note `DELETE': delete. or
     *Note `TRUNCATE TABLE': truncate, or remove the table altogether
     using *Note `DROP TABLE': drop-table.

   * If you want to populate a `MEMORY' table when the MySQL server
     starts, you can use the `--init-file' option. For example, you can
     put statements such as `INSERT INTO ...  SELECT' or *Note `LOAD
     DATA INFILE': load-data. into this file to load the table from a
     persistent data source. See *Note server-options::, and *Note
     load-data::.

   * If you are using replication, the master server's `MEMORY' tables
     become empty when it is shut down and restarted. However, a slave
     is not aware that these tables have become empty, so it returns
     out-of-date content if you select data from them. When a `MEMORY'
     table is used on the master for the first time since the master
     was started, a *Note `DELETE': delete. statement is written to the
     master's binary log automatically, thus synchronizing the slave to
     the master again. Note that even with this strategy, the slave
     still has outdated data in the table during the interval between
     the master's restart and its first use of the table. However, if
     you use the `--init-file' option to populate the `MEMORY' table on
     the master at startup, it ensures that this time interval is zero.

   * The memory needed for one row in a `MEMORY' table is calculated
     using the following expression:

          SUM_OVER_ALL_BTREE_KEYS(MAX_LENGTH_OF_KEY + sizeof(char*) x 4)
          + SUM_OVER_ALL_HASH_KEYS(sizeof(char*) x 2)
          + ALIGN(LENGTH_OF_ROW+1, sizeof(char*))

     `ALIGN()' represents a round-up factor to cause the row length to
     be an exact multiple of the `char' pointer size.  `sizeof(char*)'
     is 4 on 32-bit machines and 8 on 64-bit machines.

As mentioned earlier, the `max_heap_table_size' system variable sets
the limit on the maximum size of `MEMORY' tables. To control the
maximum size for individual tables, set the session value of this
variable before creating each table. (Do not change the global
`max_heap_table_size' value unless you intend the value to be used for
`MEMORY' tables created by all clients.) The following example creates
two `MEMORY' tables, with a maximum size of 1MB and 2MB, respectively:

     mysql> SET max_heap_table_size = 1024*1024;
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t1 (id INT, UNIQUE(id)) ENGINE = MEMORY;
     Query OK, 0 rows affected (0.01 sec)

     mysql> SET max_heap_table_size = 1024*1024*2;
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t2 (id INT, UNIQUE(id)) ENGINE = MEMORY;
     Query OK, 0 rows affected (0.00 sec)

Both tables will revert to the server's global `max_heap_table_size'
value if the server restarts.

You can also specify a `MAX_ROWS' table option in *Note `CREATE TABLE':
create-table. statements for `MEMORY' tables to provide a hint about
the number of rows you plan to store in them. This does not allow the
table to grow beyond the `max_heap_table_size' value, which still acts
as a constraint on maximum table size. For maximum flexibility in being
able to use `MAX_ROWS', set `max_heap_table_size' at least as high as
the value to which you want each `MEMORY' table to be able to grow.

*Additional resources*

   * A forum dedicated to the `MEMORY' storage engine is available at
     `http://forums.mysql.com/list.php?92'.


File: manual.info,  Node: example-storage-engine,  Next: federated-storage-engine,  Prev: memory-storage-engine,  Up: storage-engines

13.11 The `EXAMPLE' Storage Engine
==================================

The `EXAMPLE' storage engine is a stub engine that does nothing. Its
purpose is to serve as an example in the MySQL source code that
illustrates how to begin writing new storage engines. As such, it is
primarily of interest to developers.

To enable the `EXAMPLE' storage engine if you build MySQL from source,
invoke `configure' with the `--with-example-storage-engine' option.

To examine the source for the `EXAMPLE' engine, look in the
`storage/example' directory of a MySQL source distribution.

When you create an `EXAMPLE' table, the server creates a table format
file in the database directory. The file begins with the table name and
has an `.frm' extension. No other files are created. No data can be
stored into the table. Retrievals return an empty result.

     mysql> CREATE TABLE test (i INT) ENGINE = EXAMPLE;
     Query OK, 0 rows affected (0.78 sec)

     mysql> INSERT INTO test VALUES(1),(2),(3);
     ERROR 1031 (HY000): Table storage engine for 'test' doesn't »
                         have this option

     mysql> SELECT * FROM test;
     Empty set (0.31 sec)

The `EXAMPLE' storage engine does not support indexing.


File: manual.info,  Node: federated-storage-engine,  Next: archive-storage-engine,  Prev: example-storage-engine,  Up: storage-engines

13.12 The `FEDERATED' Storage Engine
====================================

* Menu:

* federated-description::        `FEDERATED' Storage Engine Overview
* federated-create::             How to Create `FEDERATED' Tables
* federated-usagenotes::         `FEDERATED' Storage Engine Notes and Tips
* federated-storage-engine-resources::  `FEDERATED' Storage Engine Resources

The `FEDERATED' storage engine enables data to be accessed from a
remote MySQL database on a local server without using replication or
cluster technology. When using a `FEDERATED' table, queries on the
local server are automatically executed on the remote (federated)
tables. No data is stored on the local tables.

To include the `FEDERATED' storage engine if you build MySQL from
source, invoke `configure' with the `--with-federated-storage-engine'
option.

Beginning with MySQL 6.0.7, the `FEDERATED' storage engine is not
enabled by default in the running server; to enable `FEDERATED', you
must start the MySQL server binary using the `--federated' option.

To examine the source for the `FEDERATED' engine, look in the
`storage/federated' directory of a MySQL source distribution.


File: manual.info,  Node: federated-description,  Next: federated-create,  Prev: federated-storage-engine,  Up: federated-storage-engine

13.12.1 `FEDERATED' Storage Engine Overview
-------------------------------------------

When you create a table using one of the standard storage engines (such
as `MyISAM', `CSV' or `InnoDB'), the table consists of the table
definition and the associated data. When you create a `FEDERATED'
table, the table definition is the same, but the physical storage of
the data is handled on a remote server.

A `FEDERATED' table consists of two elements:

   * A _remote server_ with a database table, which in turn consists of
     the table definition (stored in the `.frm' file) and the
     associated table. The table type of the remote table may be any
     type supported by the remote `mysqld' server, including `MyISAM'
     or `InnoDB'.

   * A _local server_ with a database table, where the table definition
     matches that of the corresponding table on the remote server. The
     table definition is stored within the `.frm' file. However, there
     is no data file on the local server. Instead, the table definition
     includes a connection string that points to the remote table.

When executing queries and statements on a `FEDERATED' table on the
local server, the operations that would normally insert, update or
delete information from a local data file are instead sent to the remote
server for execution, where they update the data file on the remote
server or return matching rows from the remote server.

The basic structure of a `FEDERATED' table setup is shown in *Note
figure-se-federated-structure::.

FIGURE GOES HERE: `FEDERATED' table structure

When a client issues an SQL statement that refers to a `FEDERATED'
table, the flow of information between the local server (where the SQL
statement is executed) and the remote server (where the data is
physically stored) is as follows:

  1. The storage engine looks through each column that the `FEDERATED'
     table has and constructs an appropriate SQL statement that refers
     to the remote table.

  2. The statement is sent to the remote server using the MySQL client
     API.

  3. The remote server processes the statement and the local server
     retrieves any result that the statement produces (an affected-rows
     count or a result set).

  4. If the statement produces a result set, each column is converted
     to internal storage engine format that the `FEDERATED' engine
     expects and can use to display the result to the client that
     issued the original statement.

The local server communicates with the remote server using MySQL client
C API functions. It invokes *Note `mysql_real_query()':
mysql-real-query. to send the statement. To read a result set, it uses
*Note `mysql_store_result()': mysql-store-result. and fetches rows one
at a time using *Note `mysql_fetch_row()': mysql-fetch-row.


File: manual.info,  Node: federated-create,  Next: federated-usagenotes,  Prev: federated-description,  Up: federated-storage-engine

13.12.2 How to Create `FEDERATED' Tables
----------------------------------------

* Menu:

* federated-create-connection::  Creating a `FEDERATED' Table Using `CONNECTION'
* federated-create-server::      Creating a `FEDERATED' Table Using `CREATE SERVER'

To create a `FEDERATED' table you should follow these steps:

  1. Create the table on the remote server. Alternatively, make a note
     of the table definition of an existing table, perhaps using the
     *Note `SHOW CREATE TABLE': show-create-table.  statement.

  2. Create the table on the local server with an identical table
     definition, but adding the connection information that links the
     local table to the remote table.

For example, you could create the following table on the remote server:

     CREATE TABLE test_table (
         id     INT(20) NOT NULL AUTO_INCREMENT,
         name   VARCHAR(32) NOT NULL DEFAULT '',
         other  INT(20) NOT NULL DEFAULT '0',
         PRIMARY KEY  (id),
         INDEX name (name),
         INDEX other_key (other)
     )
     ENGINE=MyISAM
     DEFAULT CHARSET=latin1;

To create the local table that will be federated to the remote table,
there are two options available. You can either create the local table
and specify the connection string (containing the server name, login,
password) to be used to connect to the remote table using the
`CONNECTION', or you can use an existing connection that you have
previously created using the *Note `CREATE SERVER': create-server.
statement.

*Important*:

When you create the local table it _must_ have an identical field
definition to the remote table.

*Note*:

You can improve the performance of a `FEDERATED' table by adding
indexes to the table on the host, even though the tables will not
actually be created locally. The optimization will occur because the
query sent to the remote server will include the contents of the
`WHERE' clause will be sent to the remote server and executed locally.
This reduces the network traffic that would otherwise request the
entire table from the server for local processing.


File: manual.info,  Node: federated-create-connection,  Next: federated-create-server,  Prev: federated-create,  Up: federated-create

13.12.2.1 Creating a `FEDERATED' Table Using `CONNECTION'
.........................................................

To use the first method, you must specify the `CONNECTION' string after
the engine type in a *Note `CREATE TABLE': create-table. statement. For
example:

     CREATE TABLE federated_table (
         id     INT(20) NOT NULL AUTO_INCREMENT,
         name   VARCHAR(32) NOT NULL DEFAULT '',
         other  INT(20) NOT NULL DEFAULT '0',
         PRIMARY KEY  (id),
         INDEX name (name),
         INDEX other_key (other)
     )
     ENGINE=FEDERATED
     DEFAULT CHARSET=latin1
     CONNECTION='mysql://fed_user@remote_host:9306/federated/test_table';

*Note*:

`CONNECTION' replaces the `COMMENT' used in some previous versions of
MySQL.

The `CONNECTION' string contains the information required to connect to
the remote server containing the table that will be used to physically
store the data. The connection string specifies the server name, login
credentials, port number and database/table information. In the
example, the remote table is on the server `remote_host', using port
9306. The name and port number should match the host name (or IP
address) and port number of the remote MySQL server instance you want
to use as your remote table.

The format the connection string is as follows:

     SCHEME://USER_NAME[:PASSWORD]@HOST_NAME[:PORT_NUM]/DB_NAME/TBL_NAME

Where:

   * SCHEME -- is a recognized connection protocol. Only `mysql' is
     supported as the SCHEME value at this point.

   * USER_NAME -- the user name for the connection. This user must have
     been created on the remote server, and must have suitable
     privileges to perform the required actions (*Note `SELECT': select,
     *Note `INSERT': insert, *Note `UPDATE': update, and so forth) on
     the remote table.

   * PASSWORD -- (optional) the corresponding password for USER_NAME.

   * HOST_NAME -- the host name or IP address of the remote server.

   * PORT_NUM -- (optional) the port number for the remote server. The
     default is 3306.

   * DB_NAME -- the name of the database holding the remote table.

   * TBL_NAME -- the name of the remote table. The name of the local
     and the remote table do not have to match.

Sample connection strings:

     CONNECTION='mysql://username:password@hostname:port/database/tablename'
     CONNECTION='mysql://username@hostname/database/tablename'
     CONNECTION='mysql://username:password@hostname/database/tablename'


File: manual.info,  Node: federated-create-server,  Prev: federated-create-connection,  Up: federated-create

13.12.2.2 Creating a `FEDERATED' Table Using `CREATE SERVER'
............................................................

If you are creating a number of `FEDERATED' tables on the same server,
or if you want to simplify the process of creating `FEDERATED' tables,
you can use the *Note `CREATE SERVER': create-server. statement to
define the server connection parameters, just as you would with the
`CONNECTION' string.

The format of the *Note `CREATE SERVER': create-server.  statement is:

     CREATE SERVER
     SERVER_NAME
     FOREIGN DATA WRAPPER WRAPPER_NAME
     OPTIONS (OPTION [, OPTION] ...)

The SERVER_NAME is used in the connection string when creating a new
`FEDERATED' table.

For example, to create a server connection identical to the
`CONNECTION' string:

     CONNECTION='mysql://fed_user@remote_host:9306/federated/test_table';

You would use the following statement:

     CREATE SERVER fedlink
     FOREIGN DATA WRAPPER mysql
     OPTIONS (USER 'fed_user', HOST 'remote_host', PORT 9306, DATABASE 'federated');

To create a `FEDERATED' table that uses this connection, you still use
the `CONNECTION' keyword, but specify the name you used in the *Note
`CREATE SERVER': create-server. statement.

     CREATE TABLE test_table (
         id     INT(20) NOT NULL AUTO_INCREMENT,
         name   VARCHAR(32) NOT NULL DEFAULT '',
         other  INT(20) NOT NULL DEFAULT '0',
         PRIMARY KEY  (id),
         INDEX name (name),
         INDEX other_key (other)
     )
     ENGINE=FEDERATED
     DEFAULT CHARSET=latin1
     CONNECTION='fedlink/test_table';

The connection name in this example contains the name of the connection
(`fedlink') and the name of the table (`test_table') to link to,
separated by a slash. If you specify only the connection name without a
table name, the table name of the local table is used instead.

For more information on *Note `CREATE SERVER': create-server, see *Note
create-server::.

The *Note `CREATE SERVER': create-server. statement accepts the same
arguments as the `CONNECTION' string. The *Note `CREATE SERVER':
create-server.  statement updates the rows in the `mysql.servers'
table. See the following table for information on the correspondence
between parameters in a connection string, options in the *Note `CREATE
SERVER': create-server. statement, and the columns in the
`mysql.servers' table. For reference, the format of the `CONNECTION'
string is as follows:

     SCHEME://USER_NAME[:PASSWORD]@HOST_NAME[:PORT_NUM]/DB_NAME/TBL_NAME

Description        `CONNECTION'       *Note `CREATE      `mysql.servers'
                   string             SERVER':           column
                                      create-server.     
                                      option             
Connection scheme  SCHEME             `wrapper_name'     `Wrapper'
Remote user        USER_NAME          `USER'             `Username'
Remote password    PASSWORD           `PASSWORD'         `Password'
Remote host        HOST_NAME          `HOST'             `Host'
Remote port        PORT_NUM           `PORT'             `Port'
Remote database    DB_NAME            `DATABASE'         `Db'


File: manual.info,  Node: federated-usagenotes,  Next: federated-storage-engine-resources,  Prev: federated-create,  Up: federated-storage-engine

13.12.3 `FEDERATED' Storage Engine Notes and Tips
-------------------------------------------------

You should be aware of the following points when using the `FEDERATED'
storage engine:

   * `FEDERATED' tables may be replicated to other slaves, but you must
     ensure that the slave servers are able to use the user/password
     combination that is defined in the `CONNECTION' string (or the row
     in the `mysql.servers' table) to connect to the remote server.

The following items indicate features that the `FEDERATED' storage
engine does and does not support:

   * The remote server must be a MySQL server. Support by `FEDERATED'
     for other database engines may be added in the future.

   * The remote table that a `FEDERATED' table points to _must_ exist
     before you try to access the table through the `FEDERATED' table.

   * It is possible for one `FEDERATED' table to point to another, but
     you must be careful not to create a loop.

   * A `FEDERATED' table does not support indexes per se. Because
     access to the table is handled remotely, it is the remote table
     that supports the indexes. Care should be taken when creating a
     `FEDERATED' table since the index definition from an equivalent
     `MyISAM' or other table may not be supported.  For example,
     creating a `FEDERATED' table with an index prefix on *Note
     `VARCHAR': char, *Note `TEXT': blob. or *Note `BLOB': blob.
     columns will fail. The following definition in `MyISAM' is valid:

          CREATE TABLE `T1`(`A` VARCHAR(100),UNIQUE KEY(`A`(30))) ENGINE=MYISAM;

     The key prefix in this example is incompatible with the
     `FEDERATED' engine, and the equivalent statement will fail:

          CREATE TABLE `T1`(`A` VARCHAR(100),UNIQUE KEY(`A`(30))) ENGINE=FEDERATED
            CONNECTION='MYSQL://127.0.0.1:3306/TEST/T1';

     If possible, you should try to separate the column and index
     definition when creating tables on both the remote server and the
     local server to avoid these index issues.

   * Internally, the implementation uses *Note `SELECT': select, *Note
     `INSERT': insert, *Note `UPDATE': update, and *Note `DELETE':
     delete, but not *Note `HANDLER': handler.

   * The `FEDERATED' storage engine supports *Note `SELECT': select,
     *Note `INSERT': insert, *Note `UPDATE': update, *Note `DELETE':
     delete, *Note `TRUNCATE': truncate, and indexes. It does not
     support *Note `ALTER TABLE': alter-table, or any Data Definition
     Language statements that directly affect the structure of the
     table, other than *Note `DROP TABLE': drop-table. The current
     implementation does not use prepared statements.

   * `FEDERATED' accepts `INSERT ... ON DUPLICATE KEY UPDATE'
     statements, but if a duplicate-key violation occurs, the statement
     fails with an error.

   * Performance on a `FEDERATED' table when performing bulk inserts
     (for example, on a `INSERT INTO ... SELECT ...' statement) is
     slower than with other table types because each selected row is
     treated as an individual *Note `INSERT': insert. statement on the
     `FEDERATED' table.

   * Transactions are supported, but distributed transactions (XA) are
     not currently supported.

   * For a multiple-row insert into a `FEDERATED' table, the storage
     engine performs bulk-insert handling such that multiple rows are
     sent to the remote table in a batch.  This provides a performance
     improvement. Also, if the remote table is transactional, it
     enables the remote storage engine to perform statement rollback
     properly should an error occur.  This capability has the following
     limitations:

        * The size of the insert cannot exceed the maximum packet size
          between servers. If the insert exceeds this size, it is
          broken into multiple packets and a rollback problem can occur
          if the remote table is transactional: The remote table can
          contain a partial commit (the rows in packets preceding the
          failed one) instead of rolling back the statement completely.

        * Bulk-insert handling does not occur for `INSERT ... ON
          DUPLICATE KEY UPDATE'.

   * There is no way for the `FEDERATED' engine to know if the remote
     table has changed. The reason for this is that this table must
     work like a data file that would never be written to by anything
     other than the database system. The integrity of the data in the
     local table could be breached if there was any change to the
     remote database.

   * When using a `CONNECTION' string, you cannot use an '@' character
     in the password. You can get round this limitation by using the
     *Note `CREATE SERVER': create-server. statement to create a server
     connection.

   * The `insert_id' and `timestamp' options are not propagated to the
     data provider.

   * Any *Note `DROP TABLE': drop-table. statement issued against a
     `FEDERATED' table drops only the local table, not the remote table.

   * `FEDERATED' tables do not work with the query cache.

   * User-defined partitioning is not supported for `FEDERATED' tables.

Some of these limitations may be lifted in future versions of the
`FEDERATED' handler.


File: manual.info,  Node: federated-storage-engine-resources,  Prev: federated-usagenotes,  Up: federated-storage-engine

13.12.4 `FEDERATED' Storage Engine Resources
--------------------------------------------

The following additional resources are available for the `FEDERATED'
storage engine:

   * A forum dedicated to the `FEDERATED' storage engine is available at
     `http://forums.mysql.com/list.php?105'.


File: manual.info,  Node: archive-storage-engine,  Next: csv-storage-engine,  Prev: federated-storage-engine,  Up: storage-engines

13.13 The `ARCHIVE' Storage Engine
==================================

The `ARCHIVE' storage engine is used for storing large amounts of data
without indexes in a very small footprint.

*Archive Features*

*Storage limits* None     *Transactions*   No       *Locking         Row
                                                    granularity*     
*MVCC*           No       *Geospatial      Yes      *Geospatial      No
                          datatype                  indexing         
                          support*                  support*         
*B-tree indexes* No       *Hash indexes*   No       *Full-text       No
                                                    search indexes*  
*Clustered       No       *Data caches*    No       *Index caches*   No
indexes*                                                             
*Compressed      Yes      *Encrypted data  Yes      *Cluster         No
data*                     Implemented in            database         
                          the server (via           support*         
                          encryption                                 
                          functions),                                
                          rather than in                             
                          the storage                                
                          engine.*                                   
*Replication     Yes      *Foreign key     No       *Backup /        Yes
support                   support*                  point-in-time    
Implemented in                                      recovery         
the server,                                         Implemented in   
rather than in                                      the server,      
the storage                                         rather than in   
engine*                                             the storage      
                                                    engine*          
*Query cache     Yes      *Update          Yes                       
support*                  statistics for                             
                          data dictionary*                           

The `ARCHIVE' storage engine is included in MySQL binary distributions.
To enable this storage engine if you build MySQL from source, invoke
`configure' with the `--with-archive-storage-engine' option.

To examine the source for the `ARCHIVE' engine, look in the
`storage/archive' directory of a MySQL source distribution.

You can check whether the `ARCHIVE' storage engine is available with
the *Note `SHOW ENGINES': show-engines.  statement.

When you create an `ARCHIVE' table, the server creates a table format
file in the database directory. The file begins with the table name and
has an `.frm' extension. The storage engine creates other files, all
having names beginning with the table name. The data file has an
extension of `.ARZ'. An `.ARN' file may appear during optimization
operations.

The `ARCHIVE' engine supports *Note `INSERT': insert. and *Note
`SELECT': select, but not *Note `DELETE': delete, *Note `REPLACE':
replace, or *Note `UPDATE': update. It does support `ORDER BY'
operations, *Note `BLOB': blob. columns, and basically all but spatial
data types (see *Note mysql-spatial-datatypes::).  The `ARCHIVE' engine
uses row-level locking.

The `ARCHIVE' engine supports the `AUTO_INCREMENT' column attribute. The
`AUTO_INCREMENT' column can have either a unique or non-unique index.
Attempting to create an index on any other column results in an error.
The `ARCHIVE' engine also supports the `AUTO_INCREMENT' table option in
*Note `CREATE TABLE': create-table. and *Note `ALTER TABLE':
alter-table. statements to specify the initial sequence value for a new
table or reset the sequence value for an existing table, respectively.

The `ARCHIVE' engine ignores *Note `BLOB': blob. columns if they are not
requested and scans past them while reading.

*Storage:* Rows are compressed as they are inserted. The `ARCHIVE'
engine uses `zlib' lossless data compression (see
`http://www.zlib.net/'). You can use *Note `OPTIMIZE TABLE':
optimize-table. to analyze the table and pack it into a smaller format
(for a reason to use *Note `OPTIMIZE TABLE': optimize-table, see later
in this section). The engine also supports *Note `CHECK TABLE':
check-table. There are several types of insertions that are used:

   * An *Note `INSERT': insert. statement just pushes rows into a
     compression buffer, and that buffer flushes as necessary. The
     insertion into the buffer is protected by a lock.  A *Note
     `SELECT': select. forces a flush to occur, unless the only
     insertions that have come in were *Note `INSERT DELAYED':
     insert-delayed. (those flush as necessary). See *Note
     insert-delayed::.

   * A bulk insert is visible only after it completes, unless other
     inserts occur at the same time, in which case it can be seen
     partially. A *Note `SELECT': select. never causes a flush of a
     bulk insert unless a normal insert occurs while it is loading.

*Retrieval*: On retrieval, rows are uncompressed on demand; there is no
row cache. A *Note `SELECT': select. operation performs a complete
table scan: When a *Note `SELECT': select. occurs, it finds out how
many rows are currently available and reads that number of rows. *Note
`SELECT': select. is performed as a consistent read. Note that lots of
*Note `SELECT': select. statements during insertion can deteriorate the
compression, unless only bulk or delayed inserts are used. To achieve
better compression, you can use *Note `OPTIMIZE TABLE': optimize-table.
or *Note `REPAIR TABLE': repair-table. The number of rows in `ARCHIVE'
tables reported by *Note `SHOW TABLE STATUS': show-table-status. is
always accurate.  See *Note optimize-table::, *Note repair-table::, and
*Note show-table-status::.

*Additional resources*

   * A forum dedicated to the `ARCHIVE' storage engine is available at
     `http://forums.mysql.com/list.php?112'.


File: manual.info,  Node: csv-storage-engine,  Next: blackhole-storage-engine,  Prev: archive-storage-engine,  Up: storage-engines

13.14 The `CSV' Storage Engine
==============================

* Menu:

* se-csv-repair::                Repairing and Checking CSV Tables
* se-csv-limitations::           CSV Limitations

The `CSV' storage engine stores data in text files using
comma-separated values format.

To enable the `CSV' storage engine if you build MySQL from source,
invoke `configure' with the `--with-csv-storage-engine' option.

To examine the source for the `CSV' engine, look in the `storage/csv'
directory of a MySQL source distribution.

When you create a `CSV' table, the server creates a table format file
in the database directory. The file begins with the table name and has
an `.frm' extension. The storage engine also creates a data file. Its
name begins with the table name and has a `.CSV' extension. The data
file is a plain text file. When you store data into the table, the
storage engine saves it into the data file in comma-separated values
format.

     mysql> CREATE TABLE test (i INT NOT NULL, c CHAR(10) NOT NULL)
         -> ENGINE = CSV;
     Query OK, 0 rows affected (0.12 sec)

     mysql> INSERT INTO test VALUES(1,'record one'),(2,'record two');
     Query OK, 2 rows affected (0.00 sec)
     Records: 2  Duplicates: 0  Warnings: 0

     mysql> SELECT * FROM test;
     +------+------------+
     | i    | c          |
     +------+------------+
     |    1 | record one |
     |    2 | record two |
     +------+------------+
     2 rows in set (0.00 sec)

Creating a CSV table also creates a corresponding Meta-file that stores
the state of the table and the number of rows that exist in the table.
The name of this file is the same as the name of the table with the
extension `CSM'.

If you examine the `test.CSV' file in the database directory created by
executing the preceding statements, its contents should look like this:

     "1","record one"
     "2","record two"

This format can be read, and even written, by spreadsheet applications
such as Microsoft Excel or StarOffice Calc.


File: manual.info,  Node: se-csv-repair,  Next: se-csv-limitations,  Prev: csv-storage-engine,  Up: csv-storage-engine

13.14.1 Repairing and Checking CSV Tables
-----------------------------------------

The CSV storage engines supports the `CHECK' and `REPAIR' commands to
verify and if possible repair a damaged CSV table.

When running the `CHECK' command, the CSV file will be checked for
validity by looking for the correct field separators, escaped fields
(matching quotes and/or missing quotes), the correct number of fields
compared to the table definition and the existence of a corresponding
CSV metafile. The first invalid row discovered will report an error.
Checking a valid table produces output like that shown below:

     mysql> check table csvtest;
     +--------------+-------+----------+----------+
     | Table        | Op    | Msg_type | Msg_text |
     +--------------+-------+----------+----------+
     | test.csvtest | check | status   | OK       |
     +--------------+-------+----------+----------+
     1 row in set (0.00 sec)

A check on a corrupted table returns a fault:

     mysql> check table csvtest;
     +--------------+-------+----------+----------+
     | Table        | Op    | Msg_type | Msg_text |
     +--------------+-------+----------+----------+
     | test.csvtest | check | error    | Corrupt  |
     +--------------+-------+----------+----------+
     1 row in set (0.01 sec)

If the check fails, the table is marked as crashed (corrupt). Once a
table has been marked as corrupt, it is automatically repaired when you
next run `CHECK' or execute a *Note `SELECT': select. statement. The
corresponding corrupt status and new status will be displayed when
running `CHECK':

     mysql> check table csvtest;
     +--------------+-------+----------+----------------------------+
     | Table        | Op    | Msg_type | Msg_text                   |
     +--------------+-------+----------+----------------------------+
     | test.csvtest | check | warning  | Table is marked as crashed |
     | test.csvtest | check | status   | OK                         |
     +--------------+-------+----------+----------------------------+
     2 rows in set (0.08 sec)

To repair a table you can use `REPAIR', this copies as many valid rows
from the existing CSV data as possible, and then replaces the existing
CSV file with the recovered rows.  Any rows beyond the corrupted data
are lost.

     mysql> repair table csvtest;
     +--------------+--------+----------+----------+
     | Table        | Op     | Msg_type | Msg_text |
     +--------------+--------+----------+----------+
     | test.csvtest | repair | status   | OK       |
     +--------------+--------+----------+----------+
     1 row in set (0.02 sec)

*Warning*:

Note that during repair, only the rows from the CSV file up to the
first damaged row are copied to the new table. All other rows from the
first damaged row to the end of the table are removed, even valid rows.


File: manual.info,  Node: se-csv-limitations,  Prev: se-csv-repair,  Up: csv-storage-engine

13.14.2 CSV Limitations
-----------------------

*Important*:

The `CSV' storage engine does not support indexing.

Partitioning is not supported for tables using the `CSV' storage engine.

Beginning with MySQL 6.0.5, tables using the `CSV' storage engine can
no longer be created with `NULL' columns. However, for backwards
compatibility, you can continue to use such tables that were created in
previous MySQL releases. (Bug#32050 (http://bugs.mysql.com/32050))


File: manual.info,  Node: blackhole-storage-engine,  Prev: csv-storage-engine,  Up: storage-engines

13.15 The `BLACKHOLE' Storage Engine
====================================

The `BLACKHOLE' storage engine acts as a `black hole' that accepts data
but throws it away and does not store it. Retrievals always return an
empty result:

     mysql> CREATE TABLE test(i INT, c CHAR(10)) ENGINE = BLACKHOLE;
     Query OK, 0 rows affected (0.03 sec)

     mysql> INSERT INTO test VALUES(1,'record one'),(2,'record two');
     Query OK, 2 rows affected (0.00 sec)
     Records: 2  Duplicates: 0  Warnings: 0

     mysql> SELECT * FROM test;
     Empty set (0.00 sec)

To enable the `BLACKHOLE' storage engine if you build MySQL from
source, invoke `configure' with the `--with-blackhole-storage-engine'
option.

To examine the source for the `BLACKHOLE' engine, look in the `sql'
directory of a MySQL source distribution.

When you create a `BLACKHOLE' table, the server creates a table format
file in the database directory. The file begins with the table name and
has an `.frm' extension. There are no other files associated with the
table.

The `BLACKHOLE' storage engine supports all kinds of indexes. That is,
you can include index declarations in the table definition.

You can check whether the `BLACKHOLE' storage engine is available with
the *Note `SHOW ENGINES': show-engines. statement.

Inserts into a `BLACKHOLE' table do not store any data, but if the
binary log is enabled, the SQL statements are logged (and replicated to
slave servers). This can be useful as a repeater or filter mechanism.
For example, suppose that your application requires slave-side
filtering rules, but transferring all binary log data to the slave
first results in too much traffic.  In such a case, it is possible to
set up on the master host a `dummy' slave process whose default storage
engine is `BLACKHOLE', depicted as follows:

Replication using `BLACKHOLE' for filtering

The master writes to its binary log. The `dummy' *Note `mysqld':
mysqld. process acts as a slave, applying the desired combination of
`replicate-do-*' and `replicate-ignore-*' rules, and writes a new,
filtered binary log of its own. (See *Note replication-options::.) This
filtered log is provided to the slave.

The dummy process does not actually store any data, so there is little
processing overhead incurred by running the additional *Note `mysqld':
mysqld. process on the replication master host.  This type of setup can
be repeated with additional replication slaves.

*Note `INSERT': insert. triggers for `BLACKHOLE' tables work as
expected. However, because the `BLACKHOLE' table does not actually
store any data, *Note `UPDATE': update. and *Note `DELETE': delete.
triggers are not activated: The `FOR EACH ROW' clause in the trigger
definition does not apply because there are no rows.

Other possible uses for the `BLACKHOLE' storage engine include:

   * Verification of dump file syntax.

   * Measurement of the overhead from binary logging, by comparing
     performance using `BLACKHOLE' with and without binary logging
     enabled.

   * `BLACKHOLE' is essentially a `no-op' storage engine, so it could
     be used for finding performance bottlenecks not related to the
     storage engine itself.

The `BLACKHOLE' engine is transaction-aware, in the sense that
committed transactions are written to the binary log and rolled-back
transactions are not.


File: manual.info,  Node: ha-overview,  Next: mem-introduction,  Prev: storage-engines,  Up: Top

14 High Availability and Scalability
************************************

* Menu:

* ha-drbd::                      Using MySQL with DRBD
* ha-heartbeat::                 Using Linux HA Heartbeat
* ha-vm::                        MySQL and Virtualization
* ha-zfs-replication::           Using ZFS Replication
* ha-memcached::                 Using MySQL with `memcached'
* mysql-proxy::                  MySQL Proxy

When using MySQL you may need to ensure the availability or scalability
of your MySQL installation. Availability refers to the ability to cope
with, and if necessary recover from, failures on the host, including
failures of MySQL, the operating system, or the hardware. Scalability
refers to the ability to spread the load of your application queries
across multiple MySQL servers. As your application and usage increases,
you may need to spread the queries for the application across multiple
servers to improve response times.

There are a number of solutions available for solving issues of
availability and scalability. The two primary solutions supported by
MySQL are MySQL Replication and MySQL Cluster. Further options are
available using third-party solutions such as DRBD (Distributed
Replicated Block Device) and Heartbeat, and more complex scenarios can
be solved through a combination of these technologies. These tools work
in different ways:

   * _MySQL Replication_ enables statements and data from one MySQL
     server instance to be replicated to another MySQL server instance.
     Without using more complex setups, data can only be replicated
     from a single master server to any number of slaves. The
     replication is asynchronous, so the synchronization does not take
     place in real time, and there is no guarantee that data from the
     master will have been replicated to the slaves.

        * *Advantages*

             * MySQL Replication is available on all platforms
               supported by MySQL, and since it isn't operating
               system-specific it can operate across different
               platforms.

             * Replication is asynchronous and can be stopped and
               restarted at any time, making it suitable for
               replicating over slower links, partial links and even
               across geographical boundaries.

             * Data can be replicated from one master to any number of
               slaves, making replication suitable in environments with
               heavy reads, but light writes (for example, many web
               applications), by spreading the load across multiple
               slaves.

        * *Disadvantages*

             * Data can only be written to the master. In advanced
               configurations, though, you can set up a multiple-master
               configuration where the data is replicated around a ring
               configuration.

             * There is no guarantee that data on master and slaves
               will be consistent at a given point in time. Because
               replication is asynchronous there may be a small delay
               between data being written to the master and it being
               available on the slaves. This can cause problems in
               applications where a write to the master must be
               available for a read on the slaves (for example a web
               application).

        * *Recommended uses*

             * Scale-out solutions that require a large number of reads
               but fewer writes (for example, web serving).

             * Logging/data analysis of live data. By replicating live
               data to a slave you can perform queries on the slave
               without affecting the operation of the master.

             * Online backup (availability), where you need an active
               copy of the data available. You need to combine this
               with other tools, such as custom scripts or Heartbeat.
               However, because of the asynchronous architecture, the
               data may be incomplete.

             * Offline backup. You can use replication to keep a copy
               of the data. By replicating the data to a slave, you
               take the slave down and get a reliable snapshot of the
               data (without MySQL running), then restart MySQL and
               replication to catch up. The master (and any other
               slaves) can be kept running during this period.

     For information on setting up and configuring replication, see
     *Note replication::.

   * _MySQL Cluster_ is a synchronous solution that enables multiple
     MySQL instances to share database information. Unlike replication,
     data in a cluster can be read from or written to any node within
     the cluster, and information will be distributed to the other
     nodes.

        * *Advantages*

             * Offers multiple read and write nodes for data storage.

             * Provides automatic failover between nodes. Only
               transaction information for the active node being used
               is lost in the event of a failure.

             * Data on nodes is instantaneously distributed to the
               other data nodes.

        * *Disadvantages*

             * Available on a limited range of platforms.

             * Nodes within a cluster should be connected via a LAN;
               geographically separate nodes are not supported.
               However, you can replicate from one cluster to another
               using MySQL Replication, although the replication in
               this case is still asynchronous.

        * *Recommended uses*

             * Applications that need very high availability, such as
               telecoms and banking.

             * Applications that require an equal or higher number of
               writes compared to reads.

     For information on MySQL Cluster, see MySQL Cluster NDB 6.X/7.X
     (http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html).

   * _DRBD (Distributed Replicated Block Device)_ is a solution from
     Linbit supported only on Linux. DRBD creates a virtual block
     device (which is associated with an underlying physical block
     device) that can be replicated from the primary server to a
     secondary server. You create a file system on the virtual block
     device, and this information is then replicated, at the block
     level, to the secondary server.

     Because the block device, not the data you are storing on it, is
     being replicated the validity of the information is more reliable
     than with data-only replication solutions. DRBD can also ensure
     data integrity by only returning from a write operation on the
     primary server when the data has been written to the underlying
     physical block device on both the primary and secondary servers.

        * *Advantages*

             * Provides high availability and data integrity across two
               servers in the event of hardware or system failure.

             * Can ensure data integrity by enforcing write consistency
               on the primary and secondary nodes.

        * *Disadvantages*

             * Only provides a method for duplicating data across the
               nodes. Secondary nodes cannot use the DRBD device while
               data is being replicated, and so the MySQL on the
               secondary node cannot be simultaneously active.

             * Can not be used to scale performance, since you can not
               redirect reads to the secondary node.

        * *Recommended uses*

             * High availability situations where concurrent access to
               the data is not required, but instant access to the
               active data in the event of a system or hardware failure
               is required.

     For information on configuring DRBD and configuring MySQL for use
     with a DRBD device, see *Note ha-drbd::.

   * _`memcached'_ is a simple, yet highly-scalable key-based cache
     that stores data and objects wherever dedicated or spare RAM is
     available for very quick access by applications. You use
     `memcached' in combination with your application and MySQL to
     reduce the number of reads from the database.

     When writing your application, you first try to load the data from
     the `memcached' cache, if the data you are looking for cannot be
     found, you then load the data from the MySQL database as normal,
     and populate the cache with the information that you loaded.
     Because `memcached' can be used to store entire objects that might
     normally consist of multiple table lookups and aggregations, you
     can significantly increase the speed of your application because
     the requirement to load data directly from the database is reduced
     or even eliminated. Because the cache is entirely in RAM, the
     response time is very fast, and the information can be distributed
     among many servers to make the best use of any spare RAM capacity.

        * *Advantages*

             * Very fast, RAM based, cache.

             * Reduces load on the MySQL server, allowing MySQL to
               concentrate on persistent storage and data writes.

             * Highly distributable and scalable, allowing multiple
               servers to be part of the cache group.

             * Highly portable - the `memcached' interface is supported
               by many languages and systems, including Perl, Python,
               PHP, Ruby, Java and the MySQL server.

        * *Disadvantages*

             * Data is not persistent - you should only use the cache
               to store information that can otherwise be loaded from a
               MySQL database.

             * Fault tolerance is implied, rather than explicit. If a
               `memcached' node fails then your application must be
               capable of loading the data from MySQL and updating the
               cache.

        * *Recommended uses*

             * High scalability situations where you have a very high
               number of reads, particularly of complex data objects
               that can easily be cached in the final, usable, form
               directly within the cache.

     For information on installing, configuring and using `memcached',
     including using the many APIs available for communicating with
     `memcached', see *Note ha-memcached::.

   * _Heartbeat_ is a software solution for Linux.  It is not a data
     replication or synchronization solution, but a solution for
     monitoring servers and switching active MySQL servers
     automatically in the event of failure. Heartbeat needs to be
     combined with MySQL Replication or DRBD to provide automatic
     failover.

     For more information on configuring Heartbeat for use with MySQL
     and DRBD, see *Note ha-heartbeat::.

The information and suitability of the various technologies and
different scenarios is summarized in the following table.

Requirements   MySQL        MySQL        MySQL        MySQL        MySQL +
               Replication  Replication  Heartbeat +  Cluster      `memcached'
                            + Heartbeat  DRBD                      
*Availability*                                                     
Automated IP   No           Yes          Yes          No           No
failover                                                           
Automated      No           No           Yes          Yes          No
database                                                           
failover                                                           
Typical        User/script-dependentVaries       < 30 seconds < 3 seconds  App
failover time                                                      dependent
Automatic      No           No           Yes          Yes          No
resynchronization                                                    
of data                                                            
Geographic     Yes          Yes          Yes, when    Yes, when    No
redundancy                               combined     combined     
support                                  with MySQL   with MySQL   
                                         Replication  Replication  
*Scalability*                                                      
Built-in load  No           No           No           Yes          Yes
balancing                                                          
Supports       Yes          Yes          Yes, when    Yes          Yes
Read-intensive                           combined                  
applications                             with MySQL                
                                         Replication               
Supports       No           No           Yes          Yes          No
Write-intensive                                                    
applications                                                       
Maximum        One master,  One master,  One active   255          Unlimited
number of      multiple     multiple     (primary),                
nodes per      slaves       slaves       one passive               
group                                    (secondary)               
                                         node                      
Maximum        Unlimited    Unlimited    One          Unlimited    Unlimited
number of      (reads only) (reads only) (failover    (reads only) 
slaves                                   only)                     


File: manual.info,  Node: ha-drbd,  Next: ha-heartbeat,  Prev: ha-overview,  Up: ha-overview

14.1 Using MySQL with DRBD
==========================

* Menu:

* ha-drbd-install::              Configuring the DRBD Environment
* ha-drbd-install-mysql::        Configuring MySQL for DRBD
* ha-drbd-performance::          Optimizing Performance and Reliability

The Distributed Replicated Block Device (DRBD) is a Linux Kernel module
that constitutes a distributed storage system. You can use DRBD to
share block devices between Linux servers and, in turn, share file
systems and data.

DRBD implements a block device which can be used for storage and which
is replicated from a primary server to one or more secondary servers.
The distributed block device is handled by the DRBD service. Writes to
the DRBD block device are distributed among the servers. Each DRBD
service writes the information from the DRBD block device to a local
physical block device (hard disk).

On the primary data writes are written both to the underlying physical
block device and distributed to the secondary DRBD services. On the
secondary, the writes received through DRBD and written to the local
physical block device. On both the primary and the secondary, reads
from the DRBD block device are handled by the underlying physical block
device. The information is shared between the primary DRBD server and
the secondary DRBD server synchronously and at a block level, and this
means that DRBD can be used in high-availability solutions where you
need failover support.

FIGURE GOES HERE: DRBD Architecture Overview

When used with MySQL, DRBD can be used to ensure availability in the
event of a failure. MySQL is configured to store information on the
DRBD block device, with one server acting as the primary and a second
machine available to operate as an immediate replacement in the event
of a failure.

For automatic failover support you can combine DRBD with the Linux
Heartbeat project, which will manage the interfaces on the two servers
and automatically configure the secondary (passive) server to replace
the primary (active) server in the event of a failure.  You can also
combine DRBD with MySQL Replication to provide both failover and
scalability within your MySQL environment.

For information on how to configure DRBD and MySQL, including Heartbeat
support, see *Note ha-drbd-install::.

An FAQ for using DRBD and MySQL is available. See *Note
faqs-mysql-drbd-heartbeat::.

*Note*:

Because DRBD is a Linux Kernel module it is currently not supported on
platforms other than Linux.


File: manual.info,  Node: ha-drbd-install,  Next: ha-drbd-install-mysql,  Prev: ha-drbd,  Up: ha-drbd

14.1.1 Configuring the DRBD Environment
---------------------------------------

* Menu:

* ha-drbd-install-os::           Setting Up Your Operating System for DRBD
* ha-drbd-install-drbd::         Installing and Configuring DRBD
* ha-drbd-install-drbd-primary::  Setting Up a DRBD Primary Node
* ha-drbd-install-drbd-secondary::  Setting Up a DRBD Secondary Node
* ha-drbd-install-drbd-using::   Monitoring DRBD Device
* ha-drbd-install-drbd-management::  Managing your DRBD Installation
* ha-drbd-install-drbd-othercfg::  Additional DRBD Configuration Options

To set up DRBD, MySQL and Heartbeat you need to follow a number of
steps that affect the operating system, DRBD and your MySQL
installation.

Before starting the installation process, you should be aware of the
following information, terms and requirements on using DRBD:

   * DRBD is a solution for enabling high-availability, and therefore
     you need to ensure that the two machines within your DRBD setup
     are as identically configured as possible so that the secondary
     machine can act as a direct replacement for the primary machine in
     the event of system failure.

   * DRBD works through two (or more) servers, each called a _node_

   * The node that contains the primary data, has read/write access to
     the data, and in an HA environment is the currently active node is
     called the _primary_.

   * The server to which the data is replicated is referred as
     _secondary_.

   * A collection of nodes that are sharing information are referred to
     as a _DRBD cluster_.

   * For DRBD to operate you must have a block device on which the
     information can be stored on _each_ DRBD node. The _lower level_
     block device can be a physical disk partition, a partition from a
     volume group or RAID device or any other block device.

     Typically you use a spare partition on which the physical data
     will be stored . On the primary node, this disk will hold the raw
     data that you want replicated. On the secondary nodes, the disk
     will hold the data replicated to the secondary server by the DRBD
     service. Ideally, the size of the partition on the two DRBD
     servers should be identical, but this is not necessary as long as
     there is enough space to hold the data that you want distributed
     between the two servers.

   * For the distribution of data to work, DRBD is used to create a
     logical block device that uses the lower level block device for
     the actual storage of information. To store information on the
     distributed device, a file system is created on the DRBD logical
     block device.

   * When used with MySQL, once the file system has been created, you
     move the MySQL data directory (including InnoDB data files and
     binary logs) to the new file system.

   * When you set up the secondary DRBD server, you set up the physical
     block device and the DRBD logical block device that will store the
     data. The block device data is then copied from the primary to the
     secondary server.

The overview for the installation and configuration sequence is as
follows:

  1. First you need to set up your operating system and environment.
     This includes setting the correct host name, updating the system
     and preparing the available packages and software required by
     DRBD, and configuring a physical block device to be used with the
     DRBD block device. See *Note ha-drbd-install-os::.

  2. Installing DRBD requires installing or compiling the DRBD source
     code and then configuring the DRBD service to set up the block
     devices that will be shared. See *Note ha-drbd-install-drbd::.

  3. Once DRBD has been configured, you must alter the configuration
     and storage location of the MySQL data. See *Note
     ha-drbd-install-mysql::.

You may optionally want to configure high availability using the Linux
Heartbeat service. See *Note ha-heartbeat::, for more information.


File: manual.info,  Node: ha-drbd-install-os,  Next: ha-drbd-install-drbd,  Prev: ha-drbd-install,  Up: ha-drbd-install

14.1.1.1 Setting Up Your Operating System for DRBD
..................................................

To set your Linux environment for using DRBD there are a number of
system configuration steps that you must follow.

   * Make sure that the primary and secondary DRBD servers have the
     correct host name, and that the host names are unique.  You can
     verify this by using the `uname' command:

          shell> uname -n
          drbd-one

     If the host name is not set correctly, edit the appropriate file
     (usually `/etc/sysconfig/network', `/etc/hostname', or
     `/etc/conf.d/hostname') and set the name correctly.

   * Each DRBD node must have a unique IP address. Make sure that the
     IP address information is set correctly within the network
     configuration and that the host name and IP address has been set
     correctly within the `/etc/hosts' file.

   * Although you can rely on the DNS or NIS system for host resolving,
     in the event of a major network failure these services may not be
     available. If possible, add the IP address and host name of each
     DRBD node into the /etc/hosts file for each machine. This will
     ensure that the node information can always be determined even if
     the DNS/NIS servers are unavailable.

   * As a general rule, the faster your network connection the better.
     Because the block device data is exchanged over the network,
     everything that will be written to the local disk on the DRBD
     primary will also be written to the network for distribution to
     the DRBD secondary.

     For tips on configuring a faster network connection see *Note
     ha-drbd-performance::.

   * You must have a spare disk or disk partition that you can use as
     the physical storage location for the DRBD data that will be
     replicated. You do not have to have a complete disk available, a
     partition on an existing disk is acceptable.

     If the disk is unpartitioned, partition the disk using `fdisk',
     `cfdisk' or other partitioning solution. Do not create a file
     system on the new partition.

     Remember that you must have a physical disk available for the
     storage of the replicated information on each DRBD node.  Ideally
     the partitions that will be used on each node should be of an
     identical size, although this is not strictly necessary. Do,
     however, ensure that the physical partition on the DRBD secondary
     is at least as big as the partitions on the DRBD primary node.

   * If possible, upgrade your system to the latest available Linux
     kernel for your distribution. Once the kernel has been installed,
     you must reboot to make the kernel active. To use DRBD you will
     also need to install the relevant kernel development and header
     files that are required for building kernel modules. Platform
     specification information for this is available later in this
     section.

Before you compile or install DRBD, you must make sure the following
tools and files are in place:

   * Kernel header files

   * Kernel source files

   * GCC Compiler

   * `glib 2'

   * `flex'

Here are some operating system specific tips for setting up your
installation:

   * *Tips for Red Hat (including CentOS and Fedora)*:

     Use `up2date' or `yum' to update and install the latest kernel and
     kernel header files:

          root-shell> up2date kernel-smp-devel kernel-smp

     Reboot. If you are going to build DRBD from source, then update
     your system with the required development packages:

          root-shell> up2date glib-devel openssl-devel libgcrypt-devel glib2-devel \
          pkgconfig ncurses-devel rpm-build rpm-devel redhat-rpm-config gcc \
          gcc-c++ bison flex gnutls-devel lm_sensors-devel net-snmp-devel \
          python-devel bzip2-devel libselinux-devel perl-DBI

     If you are going to use the pre-built DRBD RPMs:

          root-shell> up2date gnutls lm_sensors net-snmp ncurses libgcrypt glib2 openssl glib

   * *Tips for Debian, Ubuntu, Kubuntu*:

     Use `apt-get' to install the kernel packages

          root-shell> apt-get install linux-headers linux-image-server

     If you are going to use the pre-built Debian packages for DRBD
     then you should not need any additional packages.

     If you want to build DRBD from source, you will need to use the
     following command to install the required components:

          root-shell> apt-get install devscripts flex bison build-essential \
          dpkg-dev kernel-package debconf-utils dpatch debhelper \
          libnet1-dev e2fslibs-dev libglib2.0-dev automake1.9 \
          libgnutls-dev libtool libltdl3 libltdl3-dev

   * *Tips for Gentoo*:

     Gentoo is a source based Linux distribution and therefore many of
     the source files and components that you will need are either
     already installed or will be installed automatically by `emerge'.

     To install DRBD 0.8.x, you must unmask the `sys-cluster/drbd'
     build by adding the following line to
     `/etc/portage/package.keywords':

          sys-cluster/drbd ~x86
          sys-cluster/drbd-kernel ~x86

     If your kernel does not already have the userspace to kernelspace
     linker enabled, then you will need to rebuild the kernel with this
     option. The best way to do this is to use `genkernel' with the
     `--menuconfig' option to select the option and then rebuild the
     kernel. For example, at the command line as `root':

          root-shell> genkernel --menuconfig all

     Then through the menu options, select `Device Drivers', `Connector
     - unified userspace <-> kernelspace linker' and finally press 'y'
     or 'space' to select the `Connector - unified userspace <->
     kernelspace linker' option.  Then exit the menu configuration. The
     kernel will be rebuilt and installed. If this is a new kernel,
     make sure you update your bootloader accordingly. Now reboot to
     enable the new kernel.


File: manual.info,  Node: ha-drbd-install-drbd,  Next: ha-drbd-install-drbd-primary,  Prev: ha-drbd-install-os,  Up: ha-drbd-install

14.1.1.2 Installing and Configuring DRBD
........................................

To install DRBD you can choose either the pre-built binary installation
packages or you can use the source packages and build from source. If
you want to build from source you must have installed the source and
development packages.

If you are installing using a binary distribution then you must ensure
that the kernel version number of the binary package matches your
currently active kernel. You can use `uname' to find out this
information:

     shell> uname -r
     2.6.20-gentoo-r6

Once DRBD has been built and installed, you need to edit the
`/etc/drbd.conf' file and then run a number of commands to build the
block device and set up the replication.

Although the steps below are split into those for the primary node and
the secondary node, it should be noted that the configuration files for
all nodes should be identical, and many of the same steps have to be
repeated on each node to enable the DRBD block device.

Building from source:

To download and install from the source code:

  1. Download the source code.

  2. Unpack the package:

          shell> tar zxf drbd-8.3.0.tar.gz

  3. Change to the extracted directory, and then run `make' to build
     the DRBD driver:

          shell> cd drbd-8.3.0
          shell> make

  4. Install the kernel driver and commands:

          shell> make install

Binary Installation:

   * * SUSE Linux Enterprise Server (SLES)*

     For SUSE, use `yast':

          shell> yast -i drbd

     Alternatively:

          shell> rug install drbd

   * *Debian*

     Use `apt-get' to install the modules. You do not need to install
     any other components.

          shell> apt-get install drbd8-utils drbd8-module

   * *Debian 3.1 and 4.0*

     You must install the `module-assistant' to build the DRBD kernel
     module, in addition to the DRBD components.

          shell> apt-get install drbd0.7-utils drbd0.7-module-source \
            build-essential module-assistant
          shell> module-assistant auto-install drbd0.7

   * *CentOS*

     DRBD can be installed using yum:

          shell> yum install drbd kmod-drbd

   * *Ubuntu*

     You must enable the universe component for your preferred Ubuntu
     mirror in `/etc/apt/sources.list', and then issue these commands:

          shell> apt-get update
          shell> apt-get install drbd8-utils drbd8-module-source \
            build-essential module-assistant
          shell> module-assistant auto-install drbd8

   * *Gentoo*

     You can now `emerge' DRBD 0.8.x into your Gentoo installation:

          root-shell> emerge drbd

     Once `drbd' has been downloaded and installed, you need to
     decompress and copy the default configuration file from
     `/usr/share/doc/drbd-8.0.7/drbd.conf.bz2' into `/etc/drbd.conf'.


File: manual.info,  Node: ha-drbd-install-drbd-primary,  Next: ha-drbd-install-drbd-secondary,  Prev: ha-drbd-install-drbd,  Up: ha-drbd-install

14.1.1.3 Setting Up a DRBD Primary Node
.......................................

To set up a DRBD primary node you need to configure the DRBD service,
create the first DRBD block device and then create a file system on the
device so that you can store files and data.

The DRBD configuration file `/etc/drbd.conf' defines a number of
parameters for your DRBD configuration, including the frequency of
updates and block sizes, security information and the definition of the
DRBD devices that you want to create.

The key elements to configure are the `on' sections which specify the
configuration of each node.

To follow the configuration, the sequence below shows only the changes
from the default `drbd.conf' file.  Configurations within the file can
be both global or tied to specific resource.

  1. Set the synchronization rate between the two nodes. This is the
     rate at which devices are synchronized in the background after a
     disk failure, device replacement or during the initial setup. You
     should keep this in check compared to the speed of your network
     connection. Gigabit Ethernet can support up to 125 MB/second,
     100Mbps Ethernet slightly less than a tenth of that (12MBps). If
     you are using a shared network connection, rather than a
     dedicated, then you should gauge accordingly.

     To set the synchronization rate, edit the `rate' setting within the
     `syncer' block:

          syncer {
              rate 10M;
          }

     You may additionally want to set the `al-extents' parameter. The
     default for this parameter is 257.

     For more detailed information on synchronization, the effects of
     the synchronization rate and the effects on network performance,
     see *Note ha-drbd-performance-syncrate::.

  2. Set up some basic authentication. DRBD supports a simple password
     hash exchange mechanism. This helps to ensure that only those
     hosts with the same shared secret are able to join the DRBD node
     group.

          cram-hmac-alg "sha1";
          shared-secret "SHARED-STRING";

  3. Now you must configure the host information. Remember that you
     must have the node information for the primary and secondary nodes
     in the `drbd.conf' file on each host. You need to configure the
     following information for each node:

        * `device' -- the path of the logical block device that will be
          created by DRBD.

        * `disk' -- the block device that will be used to store the
          data.

        * `address' -- the IP address and port number of the host that
          will hold this DRBD device.

        * `meta-disk' -- the location where the metadata about the DRBD
          device will be stored. You can set this to `internal' and DRBD
          will use the physical block device to store the information,
          by recording the metadata within the last sections of the
          disk. The exact size will depend on the size of the logical
          block device you have created, but it may involve up to 128MB.

     A sample configuration for our primary server might look like this:

          on drbd-one {
          device /dev/drbd0;
          disk /dev/hdd1;
          address 192.168.0.240:8888;
          meta-disk internal;
          }

     The `on' configuration block should be repeated for the secondary
     node (and any further) nodes:

          on drbd-two {
          device /dev/drbd0;
          disk /dev/hdd1;
          address 192.168.0.241:8888;
          meta-disk internal;
          }

     The IP address of each `on' block must match the IP address of the
     corresponding host. Do not set this value to the IP address of the
     corresponding primary or secondary in each case.

  4. Before starting the primary node, you should create the metadata
     for the devices:

          root-shell> drbdadm create-md all

  5. You are now ready to start DRBD:

          root-shell> /etc/init.d/drbd start

     DRBD should now start and initialize, creating the DRBD devices
     that you have configured.

  6. DRBD creates a standard block device - to make it usable, you must
     create a file system on the block device just as you would with
     any standard disk partition. Before you can create the file
     system, you must mark the new device as the primary device (i.e.
     where the data will be written and stored), and initialize the
     device. Because this is a destructive operation, you must specify
     the command line option to overwrite the raw data:

          root-shell> drbdadm -- --overwrite-data-of-peer primary all

     If you are using a version of DRBD 0.7.x or earlier, then you need
     to use a different command-line option:

          root-shell> drbdadm -- --do-what-I-say primary all

     Now create a file system using your chosen file system type:

          root-shell> mkfs.ext3 /dev/drbd0

  7. You can now mount the file system and if necessary copy files to
     the mount point:

          root-shell> mkdir /mnt/drbd
          root-shell> mount /dev/drbd0 /mnt/drbd
          root-shell> echo "DRBD Device" >/mnt/drbd/samplefile

Your primary node is now ready to use. You should now configure your
secondary node or nodes.


File: manual.info,  Node: ha-drbd-install-drbd-secondary,  Next: ha-drbd-install-drbd-using,  Prev: ha-drbd-install-drbd-primary,  Up: ha-drbd-install

14.1.1.4 Setting Up a DRBD Secondary Node
.........................................

The configuration process for setting up a secondary node is the same
as for the primary node, except that you do not have to create the file
system on the secondary node device, as this information will
automatically be transferred from the primary node.

To set up a secondary node:

  1. Copy the `/etc/drbd.conf' file from your primary node to your
     secondary node. It should already contain all the information and
     configuration that you need, since you had to specify the
     secondary node IP address and other information for the primary
     node configuration.

  2. Create the DRBD metadata on the underlying disk device:

          root-shell> drbdadm create-md all

  3. Start DRBD:

          root-shell> /etc/init.d/drbd start

Once DRBD has started, it will start the copy the data from the primary
node to the secondary node. Even with an empty file system this will
take some time, since DRBD is copying the block information from a
block device, not simply copying the file system data.

You can monitor the progress of the copy between the primary and
secondary nodes by viewing the output of `/proc/drbd':

     root-shell> cat /proc/drbd
     version: 8.0.4 (api:86/proto:86)
     SVN Revision: 2947 build by root@drbd-one, 2007-07-30 16:43:05
      0: cs:SyncSource st:Primary/Secondary ds:UpToDate/Inconsistent C r---
         ns:252284 nr:0 dw:0 dr:257280 al:0 bm:15 lo:0 pe:7 ua:157 ap:0
             [==>.................] sync'ed: 12.3% (1845088/2097152)K
             finish: 0:06:06 speed: 4,972 (4,580) K/sec
             resync: used:1/31 hits:15901 misses:16 starving:0 dirty:0 changed:16
             act_log: used:0/257 hits:0 misses:0 starving:0 dirty:0 changed:0

You can monitor the synchronization process by using the `watch'
command to run the command at specific intervals:

     root-shell> watch -n 10 'cat /proc/drbd'


File: manual.info,  Node: ha-drbd-install-drbd-using,  Next: ha-drbd-install-drbd-management,  Prev: ha-drbd-install-drbd-secondary,  Up: ha-drbd-install

14.1.1.5 Monitoring DRBD Device
...............................

Once the primary and secondary machines are configured and
synchronized, you can get the status information about your DRBD device
by viewing the output from `/proc/drbd':

     root-shell> cat /proc/drbd
     version: 8.0.4 (api:86/proto:86)
     SVN Revision: 2947 build by root@drbd-one, 2007-07-30 16:43:05
      0: cs:Connected st:Primary/Secondary ds:UpToDate/UpToDate C r---
         ns:2175704 nr:0 dw:99192 dr:2076641 al:33 bm:128 lo:0 pe:0 ua:0 ap:0
             resync: used:0/31 hits:134841 misses:135 starving:0 dirty:0 changed:135
             act_log: used:0/257 hits:24765 misses:33 starving:0 dirty:0 changed:33

The first line provides the version/revision and build information.

The second line starts the detailed status information for an
individual resource. The individual field headings are as follows:

   * cs -- connection state

   * st -- node state (local/remote)

   * ld -- local data consistency

   * ds -- data consistency

   * ns -- network send

   * nr -- network receive

   * dw -- disk write

   * dr -- disk read

   * pe -- pending (waiting for ack)

   * ua -- unack'd (still need to send ack)

   * al -- access log write count

In the previous example, the information shown indicates that the nodes
are connected, the local node is the primary (because it is listed
first), and the local and remote data is up to date with each other.
The remainder of the information is statistical data about the device,
and the data exchanged that kept the information up to date.

You can also get the status information for DRBD by using the startup
script with the `status' option:

     root-shell> /etc/init.d/drbd status
      * status:  started
      * drbd driver loaded OK; device status: ...                                                                                      [ ok ]
     version: 8.3.0 (api:88/proto:86-89)
     GIT-hash: 9ba8b93e24d842f0dd3fb1f9b90e8348ddb95829 build by root@gentoo1.vmbear, 2009-03-14 23:00:06
      0: cs:Connected ro:Secondary/Secondary ds:UpToDate/UpToDate C r---
         ns:0 nr:0 dw:0 dr:8385604 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:0

The information and statistics are the same.


File: manual.info,  Node: ha-drbd-install-drbd-management,  Next: ha-drbd-install-drbd-othercfg,  Prev: ha-drbd-install-drbd-using,  Up: ha-drbd-install

14.1.1.6 Managing your DRBD Installation
........................................

For administration, the main command is `drbdadm'. There are a number
of commands supported by this tool the control the connectivity and
status of the DRBD devices.

*Note*:

For convenience, a bash completion script is available. This will
provide tab completion for options to `drbdadm'. The file
`drbdadm.bash_completion' can be found within the standard DRBD source
package within the `scripts' directory. To enable, copy the file to
`/etc/bash_completion.d/drbdadm'.  You can load it manually by using:

     shell> source /etc/bash_completion.d/drbdadm

The most common commands are those to set the primary/secondary status
of the local device. You can manually set this information for a number
of reasons, including when you want to check the physical status of the
secondary device (since you cannot mount a DRBD device in primary
mode), or when you are temporarily moving the responsibility of keeping
the data in check to a different machine (for example, during an
upgrade or physical move of the normal primary node). You can set state
of all local device to be the primary using this command:

     root-shell> drbdadm primary all

Or switch the local device to be the secondary using:

     root-shell> drbdadm secondary all

To change only a single DRBD resource, specify the resource name
instead of `all'.

You can temporarily disconnect the DRBD nodes:

     root-shell> drbdadm disconnect all

Reconnect them using `connect':

     root-shell> drbdadm connect all

For other commands and help with `drbdadm' see the DRBD documentation.


File: manual.info,  Node: ha-drbd-install-drbd-othercfg,  Prev: ha-drbd-install-drbd-management,  Up: ha-drbd-install

14.1.1.7 Additional DRBD Configuration Options
..............................................

Additional options you may want to configure:

   * `protocol' -- specifies the level of consistency to be used when
     information is written to the block device. The option is similar
     in principle to the `innodb_flush_log_at_trx_commit' option within
     MySQL. Three levels are supported:

        * `A' -- data is considered written when the information
          reaches the TCP send buffer and the local physical disk.
          There is no guarantee that the data has been written to the
          remote server or the remote physical disk.

        * `B' -- data is considered written when the data has reached
          the local disk and the remote node's network buffer. The data
          has reached the remote server, but there is no guarantee it
          has reached the remote server's physical disk.

        * `C' -- data is considered written when the data has reached
          the local disk and the remote node's physical disk.

     The preferred and recommended protocol is C, as it is the only
     protocol which ensures the consistency of the local and remote
     physical storage.

   * `size' -- if you do not want to use the entire partition space
     with your DRBD block device then you can specify the size of the
     DRBD device to be created.  The size specification can include a
     quantifier. For example, to set the maximum size of the DRBD
     partition to 1GB you would use:

          size 1G;

With the configuration file suitably configured and ready to use, you
now need to populate the lower-level device with the metadata
information, and then start the DRBD service.


File: manual.info,  Node: ha-drbd-install-mysql,  Next: ha-drbd-performance,  Prev: ha-drbd-install,  Up: ha-drbd

14.1.2 Configuring MySQL for DRBD
---------------------------------

Once you have configured DRBD and have an active DRBD device and file
system, you can configure MySQL to use the chosen device to store the
MySQL data.

When performing a new installation of MySQL, you can either select to
install MySQL entirely onto the DRBD device, or just configure the data
directory to be located on the new file system.

In either case, the files and installation must take place on the
primary node, because that is the only DRBD node on which you can mount
the DRBD device file system as read/write.

You should store the following files and information on your DRBD
device:

   * MySQL data files, including the binary log, and InnoDB data files.

   * MySQL configuration file (`my.cnf').

To set up MySQL to use your new DRBD device and file system:

  1. If you are migrating an existing MySQL installation, stop MySQL:

          shell> mysqladmin shutdown

  2. Copy the `my.cnf' onto the DRBD device. If you are not already
     using a configuration file, copy one of the sample configuration
     files from the MySQL distribution.

          root-shell> mkdir /mnt/drbd/mysql
          root-shell> cp /etc/my.cnf /mnt/drbd/mysql

  3. Copy your MySQL data directory to the DRBD device and mounted file
     system.

          root-shell> cp -R /var/lib/mysql /drbd/mysql/data

  4. Edit the configuration file to reflect the change of directory by
     setting the value of the `datadir' option. If you have not already
     enabled the binary log, also set the value of the `log-bin' option.

          datadir = /drbd/mysql/data
            log-bin = mysql-bin

  5. Create a symbolic link from `/etc/my.cnf' to the new configuration
     file on the DRBD device file system.

          root-shell> ln -s /drbd/mysql/my.cnf /etc/my.cnf

  6. Now start MySQL and check that the data that you copied to the
     DRBD device file system is present.

          root-shell> /etc/init.d/mysql start

Your MySQL data should now be located on the file system running on
your DRBD device. The data will be physically stored on the underlying
device that you configured for the DRBD device.  Meanwhile, the content
of your MySQL databases will be copied to the secondary DRBD node.

Note that you cannot access the information on your secondary node, as
a DRBD device working in secondary mode is not available for use.


File: manual.info,  Node: ha-drbd-performance,  Prev: ha-drbd-install-mysql,  Up: ha-drbd

14.1.3 Optimizing Performance and Reliability
---------------------------------------------

* Menu:

* ha-drbd-performance-bonded::   Using Bonded Ethernet Network Interfaces
* ha-drbd-performance-syncrate::  Optimizing the Synchronization Rate

Because of the nature of the DRBD system, the critical requirements are
for a very fast exchange of the information between the two hosts. To
ensure that your DRBD setup is available to switch over in the event of
a failure as quickly as possible, you must transfer the information
between the two hosts using the fastest method available.

Typically, a dedicated network circuit should be used for exchanging
DRBD data between the two hosts. You should then use a separate,
additional, network interface for your standard network connection. For
an example of this layout, see *Note ha-drbd-performance-sepinterface::.

FIGURE GOES HERE: DRBD Architecture Using Separate Network Interfaces

The dedicated DRBD network interfaces should be configured to use a
non-routed TCP/IP network configuration. For example, you might want to
set the primary to use 192.168.0.1 and the secondary 192.168.0.2. These
networks and IP addresses should not be part of normal network subnet.

*Note*:

The preferred setup, whenever possible, is to use a direct cable
connection (using a crossover cable with Ethernet, for example) between
the two machines. This eliminates the risk of loss of connectivity due
to switch failures.


File: manual.info,  Node: ha-drbd-performance-bonded,  Next: ha-drbd-performance-syncrate,  Prev: ha-drbd-performance,  Up: ha-drbd-performance

14.1.3.1 Using Bonded Ethernet Network Interfaces
.................................................

For a set-up where there is a high-throughput of information being
written, you may want to use bonded network interfaces.  This is where
you combine the connectivity of more than one network port, increasing
the throughput linearly according to the number of bonded connections.

Bonding also provides an additional benefit in that with multiple
network interfaces effectively supporting the same communications
channel, a fault within a single network interface in a bonded group
does not stop communication. For example, imagine you have a bonded
setup with four network interfaces providing a single interface channel
between two DRBD servers. If one network interface fails, communication
can continue on the other three without interruption, although it will
be at a lower speed

To enable bonded connections you must enable bonding within the kernel.
You then need to configure the module to specify the bonded devices and
then configure each new bonded device just as you would a standard
network device:

   * To configure the bonded devices, you need to edit the
     `/etc/modprobe.conf' file (RedHat) or add a file to the
     `/etc/modprobe.d' directory.. In each case you will define the
     parameters for the kernel module. First, you need to specify each
     bonding device:

          alias bond0 bonding

     You can then configure additional parameters for the kernel
     module. Typical parameters are the `mode' option and the `miimon'
     option.

     The `mode' option specifies how the network interfaces are used.
     The default setting is 0, which means that each network interface
     is used in a round-robin fashion (this supports aggregation and
     fault tolerance). Using setting 1 sets the bonding mode to
     active-backup. This means that only one network interface is used
     as a time, but that the link will automatically failover to a new
     interface if the primary interface fails. This settings only
     supports fault-tolerance.

     The `miimon' option enables the MII link monitoring. A positive
     value greater than zero indicates the monitoring frequency in
     milliseconds for checking each slave network interface that is
     configured as part of the bonded interface. A typical value is 100.

     You set th options within the module parameter file, and you must
     set the options for each bonded device individually:

          options bond0 miimon=100 mode=1

   * Reboot your server to enable the bonded devices.

   * Configure the network device parameters. There are two parts to
     this, you need to setup the bonded device configuration, and then
     configure the original network interfaces as 'slaves' of the new
     bonded interface.

        * For RedHat Linux:

          Edit the configuration file for the bonded device. For device
          `bond0' this would be
          `/etc/sysconfig/network-scripts/ifcfg-bond0':

               DEVICE=bond0
               BOOTPROTO=none
               ONBOOT=yes
               GATEWAY=192.168.0.254
               NETWORK=192.168.0.0
               NETMASK=255.255.255.0
               IPADDR=192.168.0.1
               USERCTL=no

          Then for each network interface that you want to be part of
          the bonded device, configure the interface as a slave to the
          'master' bond. For example, the configuration of `eth0' in
          `/etc/sysconfig/network-scripts/ifcfg-eth0' might look like
          this::

               DEVICE=eth0
               BOOTPROTO=none
               HWADDR=00:11:22:33:44:55
               ONBOOT=yes
               TYPE=Ethernet
               MASTER=bond0
               SLAVE=yes

        * For Debian Linux:

          Edit the `/etc/iftab' file and configure the logical name and
          MAC address for each devices. For example:

               eth0 mac 00:11:22:33:44:55

          Now you need to set the configuration of the devices in
          `/etc/network/interfaces':

               auto bond0
                   iface bond0 inet static
                   address 192.168.0.1
                   netmask 255.255.255.0
                   network 192.168.0.0
                   gateway 192.168.0.254
                   up /sbin/ifenslave bond0 eth0
                   up /sbin/ifenslave bond0 eth1

        * For Gentoo:

          Use `emerge' to add the `net-misc/ifenslave' package to your
          system.

          Edit the `/etc/conf.d/net' file and specify the network
          interface slaves in a bond, the dependencies and then the
          configuration for the bond itself. A sample configuration
          might look like this:

               slaves_bond0="eth0 eth1 eth2"

               config_bond0=( "192.168.0.1 netmask 255.255.255.0"  )

               depend_bond0() {
               need net.eth0 net.eth1 net.eth2
               }

          Then make sure that you add the new network interface to list
          of interfaces configured during boot:

               root-shell> rc-update add default net.bond0

Once the bonded devices are configured you should reboot your systems.

You can monitor the status of a bonded connection using the `/proc'
file system:

     root-shell> cat /proc/net/bonding/bond0
     Bonding Mode: fault-tolerance (active-backup)
     Primary Slave: None
     Currently Active Slave: eth1
     MII Status: up
     MII Polling Interval (ms): 100
     Up Delay (ms): 200
     Down Delay (ms): 200
     Slave Interface: eth1
     MII Status: up
     Link Failure Count: 0
     Permanent HW addr: 00:11:22:33:44:55
     Slave Interface: eth2
     MII Status: up
     Link Failure Count: 0
     Permanent HW addr: 00:11:22:33:44:56


File: manual.info,  Node: ha-drbd-performance-syncrate,  Prev: ha-drbd-performance-bonded,  Up: ha-drbd-performance

14.1.3.2 Optimizing the Synchronization Rate
............................................

The `syncer rate' configuration parameter should be configured with
care as the synchronization rate can have a significant effect on the
performance of the DRBD setup in the event of a node or disk failure
where the information is being synchronized from the Primary to the
Secondary node.

In DRBD, there are two distinct ways of data being transferred between
peer nodes:

   * _Replication_ refers to the transfer of modified blocks being
     transferred from the primary to the secondary node. This happens
     automatically when the block is modified on the primary node, and
     the replication process uses whatever bandwidth is available over
     the replication link. The replication process cannot be throttled,
     because you want to transfer of the block information to happen as
     quickly as possible during normal operation.

   * _Synchronization_ refers to the process of bringing peers back in
     sync after some sort of outage, due to manual intervention, node
     failure, disk swap, or the initial setup. Synchronization is
     limited to the `syncer rate' configured for the DRBD device.

Both replication and synchronization can take place at the same time.
For example, the block devices can be being synchronized while they are
actively being used by the primary node. Any I/O that updates on the
primary node will automatically trigger replication of the modified
block. In the event of a failure within an HA environment, it is highly
likely that synchronization and replication will take place at the same
time.

Unfortunately, if the synchronization rate is set too high, then the
synchronization process will use up all the available network bandwidth
between the primary and secondary nodes. In turn, the bandwidth
available for replication of changed blocks is zero, which means
replication will stall and I/O will block, and ultimately the
application will fail or degrade.

To avoid enabling the `syncer rate' to consume the available network
bandwidth and prevent the replication of changed blocks you should set
the `syncer rate' to less than the maximum network bandwidth.

You should avoid setting the sync rate to more than 30% of the maximum
bandwidth available to your device and network bandwidth. For example,
if your network bandwidth is based on Gigabit ethernet, you should
achieve 110MB/s. Assuming your disk interface is capable of handling
data at 110MB/s or more, then the sync rate should be configered as
`33M' (33MB/s). If your disk system works at a rate lower than your
network interface, use 30% of your disk interface speed.

Depending on the application, you may wish to limit the synchronization
rate. For example, on a busy server you may wish to configure a
significantly slower synchronization rate to ensure the replication
rate is not affected.

The `al-extents' parameter controls the number of 4MB blocks of the
underlying disk that can be written to at the same time. Increasing
this parameter lowers the frequency of the meta data transactions
required to log the changes to the DRBD device, which in turn lowers
the number of interruptions in your I/O stream when synchronizing
changes. This can lower the latency of changes to the DRBD device.
However, if a crash occurs on your primary, then all of the blocks in
the activity log (i.e. the number of `al-extents' blocks) will need to
be completely resynchronized before replication can continue.


File: manual.info,  Node: ha-heartbeat,  Next: ha-vm,  Prev: ha-drbd,  Up: ha-overview

14.2 Using Linux HA Heartbeat
=============================

* Menu:

* ha-heartbeat-config::          Heartbeat Configuration
* ha-heartbeat-drbd::            Using Heartbeat with MySQL and DRBD
* ha-heartbeat-drbd-dopd::       Using Heartbeat with DRBD and `dopd'
* ha-heartbeat-errors::          Dealing with System Level Errors

The Heartbeat program provides a basis for verifying the availability
of resources on one or more systems within a cluster.  In this context
a resource includes MySQL, the file systems on which the MySQL data is
being stored and, if you are using DRBD, the DRBD device being used for
the file system. Heartbeat also manages a virtual IP address, and the
virtual IP address should be used for all communication to the MySQL
instance.

A cluster within the context of Heartbeat is defined as two computers
notionally providing the same service. By definition, each computer in
the cluster is physically capable of providing the same services as all
the others in the cluster. However, because the cluster is designed for
high-availability, only one of the servers is actively providing the
service at any one time. Each additional server within the cluster is a
`hot-spare' that can be brought into service in the event of a failure
of the master, its next connectivity or the connectivity of the network
in general.

The basics of Heartbeat are very simple. Within the Heartbeat cluster
(see *Note ha-heartbeat-overview::, each machine sends a 'heartbeat'
signal to the other hosts in the cluster. The other cluster nodes
monitor this heartbeat. The heartbeat can be transmitted over many
different systems, including shared network devices, dedicated network
interfaces and serial connections.  Failure to get a heartbeat from a
node is treated as failure of the node. Although we do not know the
reason for the failure (it could be an OS failure, a hardware failure
in the server, or a failure in the network switch), it is safe to
assume that if no heartbeat is produced there is a fault.

FIGURE GOES HERE: Heartbeat Architecture

In addition to checking the heartbeat from the server, the system can
also check the connectivity (using `ping') to another host on the
network, such as the network router. This allows Heartbeat to detect a
failure of communication between a server and the router (and therefore
failure of the server, since it is no longer capable of providing the
necessary service), even if the heartbeat between the servers in the
clusters is working fine.

In the event of a failure, the resources on the failed host are
disabled, and the resources on one of the replacement hosts is enabled
instead. In addition, the Virtual IP address for the cluster is
redirected to the new host in place of the failed device.

When used with MySQL and DRBD, the MySQL data is replicated from the
master to the slave using the DRBD device, but MySQL is only running on
the master. When the master fails, the slave switches the DRBD devices
to be primary, the file systems on those devices are mounted, and MySQL
is started. The original master (if still available) has its resources
disabled, which means shutting down MySQL and unmounting the file
systems and switching the DRBD device to secondary.


File: manual.info,  Node: ha-heartbeat-config,  Next: ha-heartbeat-drbd,  Prev: ha-heartbeat,  Up: ha-heartbeat

14.2.1 Heartbeat Configuration
------------------------------

Heartbeat configuration requires three files located in `/etc/ha.d'.
The `ha.cf' contains the main heartbeat configuration, including the
list of the nodes and times for identifying failures.  `haresources'
contains the list of resources to be managed within the cluster. The
`authkeys' file contains the security information for the cluster.

The contents of these files should be identical on each host within the
Heartbeat cluster. It is important that you keep these files in sync
across all the hosts. Any changes in the information on one host should
be copied to the all the others.

For these examples n example of the `ha.cf' file is shown below:

     logfacility local0
     keepalive 500ms
     deadtime 10
     warntime 5
     initdead 30
     mcast bond0 225.0.0.1 694 2 0
     mcast bond1 225.0.0.2 694 1 0
     auto_failback off
     node drbd1
     node drbd2

The individual lines in the file can be identified as follows:

   * `logfacility' -- sets the logging, in this case setting the
     logging to use `syslog'.

   * `keepalive' -- defines how frequently the heartbeat signal is sent
     to the other hosts.

   * `deadtime'-- the delay in seconds before other hosts in the
     cluster are considered 'dead' (failed).

   * `warntime' -- the delay in seconds before a warning is written to
     the log that a node cannot be contacted.

   * `initdead' -- the period in seconds to wait during system startup
     before the other host is considered to be down.

   * `mcast' -- defines a method for sending a heartbeat signal. In the
     above example, a multicast network address is being used over a
     bonded network device. If you have multiple clusters then the
     multicast address for each cluster should be unique on your
     network. Other choices for the heartbeat exchange exist, including
     a serial connection.

     If you are using multiple network interfaces (for example, one
     interface for your server connectivity and a secondary and/or
     bonded interface for your DRBD data exchange) then you should use
     both interfaces for your heartbeat connection. This decreases the
     chance of a transient failure causing a invalid failure event.

   * `auto_failback' -- sets whether the original (preferred) server
     should be enabled again if it becomes available. Switching this to
     `on' may cause problems if the preferred went offline and then
     comes back on line again. If the DRBD device has not been synced
     properly, or if the problem with the original server happens again
     you may end up with two different datasets on the two servers, or
     with a continually changing environment where the two servers
     flip-flop as the preferred server reboots and then starts again.

   * `node' -- sets the nodes within the Heartbeat cluster group. There
     should be one `node' for each server.

An optional additional set of information provides the configuration
for a ping test that will check the connectivity to another host. You
should use this to ensure that you have connectivity on the public
interface for your servers, so the ping test should be to a reliable
host such as a router or switch. The additional lines specify the
destination machine for the `ping', which should be specified as an IP
address, rather than a host name; the command to run when a failure
occurs, the authority for the failure and the timeout before an
non-response triggers a failure. A sample configure is shown below:

     ping 10.0.0.1
     respawn hacluster /usr/lib64/heartbeat/ipfail
     apiauth ipfail gid=haclient uid=hacluster
     deadping 5

In the above example, the `ipfail' command, which is part of the
Heartbeat solution, is called on a failure and 'fakes' a fault on the
currently active server. You need to configure the user and group ID
under which the command should be executed (using the `apiauth'). The
failure will be triggered after 5 seconds.

*Note*:

The `deadping' value must be less than the `deadtime' value.

The `authkeys' file holds the authorization information for the
Heartbeat cluster. The authorization relies on a single unique 'key'
that is used to verify the two machines in the Heartbeat cluster. The
file is used only to confirm that the two machines are in the same
cluster and is used to ensure that the multiple clusters can co-exist
within the same network.


File: manual.info,  Node: ha-heartbeat-drbd,  Next: ha-heartbeat-drbd-dopd,  Prev: ha-heartbeat-config,  Up: ha-heartbeat

14.2.2 Using Heartbeat with MySQL and DRBD
------------------------------------------

To use Heartbeat in combination with MySQL you should be using DRBD
(see *Note ha-drbd::) or another solution that allows for sharing of
the MySQL database files in event of a system failure. In these
examples, DRBD is used as the data sharing solution.

Heartbeat manages the configuration of different resources to manage
the switching between two servers in the event of a failure. The
resource configuration defines the individual services that should be
brought up (or taken down) in the event of a failure.

The `haresources' file within `/etc/ha.d' defines the resources that
should be managed, and the individual resource mentioned in this file in
turn relates to scripts located within `/etc/ha.d/resource.d'. The
resource definition is defined all on one line:

     drbd1 drbddisk Filesystem::/dev/drbd0::/drbd::ext3 mysql 10.0.0.100

The line is notionally split by whitespace. The first entry (`drbd1')
is the name of the preferred host, i.e.  the server that is normally
responsible for handling the service.  The last field is virtual IP
address or name that should be used to share the service. This is the
IP address that should be used to connect to the MySQL server. It will
automatically be allocated to the server that is active when Heartbeat
starts.

The remaining fields between these two fields define the resources that
should be managed. Each Field should contain the name of the resource
(and each name should refer to a script within `/etc/ha.d/resource.d').
In the event of a failure, these resources are started on the backup
server by calling the corresponding script (with a single argument,
`start'), in order from left to right. If there are additional
arguments to the script, you can use a double colon to separate each
additional argument.

In the above example, we manage the following resources:

   * `drbddisk' -- the DRBD resource script, this will switch the DRBD
     disk on the secondary host into primary mode, making the device
     read/write.

   * `Filesystem' -- manages the Filesystem resource. In this case we
     have supplied additional arguments to specify the DRBD device,
     mount point and file system type.  When executed this should mount
     the specified file system.

   * `mysql' -- manages the MySQL instances and starts the MySQL
     server. You should copy the `mysql.resource' file from the
     `support-files' directory from any MySQL release into the
     `/etc/ha.d/resources.d' directory.

     If this file is not available in your distribution, you can use
     the following as the contents of the
     `/etc/ha.d/resource.d/mysql.resource' file:

          #!/bin/bash
          #
          # This script is inteded to be used as resource script by heartbeat
          #
          # Mar 2006 by Monty Taylor
          #
          ###

          . /etc/ha.d/shellfuncs

          case "$1" in
              start)
                  res=`/etc/init.d/mysql start`
                  ret=$?
                  ha_log $res
                  exit $ret
                  ;;
              stop)
                  res=`/etc/init.d/mysql stop`
                  ret=$?
                  ha_log $res
                  exit $ret
                  ;;
              status)
                  if [ `ps -ef | grep '[m]ysqld'` ] ; then
                     echo "running"
                  else
                     echo "stopped"
                  fi
                  ;;
              *)
                  echo "Usage: mysql {start|stop|status}"
                  exit 1
                  ;;
          esac

          exit 0

If you want to be notified of the failure by email, you can add another
line to the `haresources' file with the address for warnings and the
warning text:

     MailTo::youremail@address.com::DRBDFailure

With the Heartbeat configuration in place, copy the `haresources',
`authkeys' and `ha.cf' files from your primary and secondary servers to
make sure that the configuration is identical. Then start the Heartbeat
service, either by calling `/etc/init.d/heartbeat start' or by rebooting
both primary and secondary servers.

You can test the configuration by running a manual failover, connect to
the primary node and run:

     root-shell> /usr/lib64/heartbeat/hb_standby

This will cause the current node to relinquish its resources cleanly to
the other node.


File: manual.info,  Node: ha-heartbeat-drbd-dopd,  Next: ha-heartbeat-errors,  Prev: ha-heartbeat-drbd,  Up: ha-heartbeat

14.2.3 Using Heartbeat with DRBD and `dopd'
-------------------------------------------

As a further extension to using DRBD and Heartbeat together, you can
enable `dopd'. The `dopd' daemon handles the situation where a DRBD
node is out of date compared to the master and prevents the slave from
being promoted to master in the event of a failure. This stops a
situation where you have two machines that have been masters ending up
different data on the underlying device.

For example, imagine that you have a two server DRBD setup, master and
slave. If the DRBD connectivity between master and slave fails then the
slave would be out of the sync with the master. If Heartbeat identifies
a connectivity issue for master and then switches over to the slave,
the slave DRBD device will be promoted to the primary device, even
though the data on the slave and the master is not in synchronization.

In this situation, with `dopd' enabled, the connectivity failure
between the master and slave would be identified and the metadata on
the slave would be set to `Outdated'. Heartbeat will then refuse to
switch over to the slave even if the master failed. In a dual-host
solution this would effectively render the cluster out of action, as
there is no additional fail over server. In an HA cluster with three or
more servers, control would be passed to the slave that has an up to
date version of the DRBD device data.

To enable `dopd', you need to modify the Heartbeat configuration and
specify `dopd' as part of the commands executed during the monitoring
process. Add the following lines to your `ha.cf' file:

     respawn hacluster /usr/lib/heartbeat/dopd
     apiauth dopd gid=haclient uid=hacluster

Make sure you make the same modification on both your primary and
secondary nodes.

You will need to reload the Heartbeat configuration:

     root-shell> /etc/init.d/heartbeat reload

You will also need to modify your DRBD configuration by configuration
the `outdate-peer' option. You will need to add the configuration line
into the `common' section of `/etc/drbd.conf' on both hosts. An example
of the full block is shown below:

     common {
       handlers {
         outdate-peer "/usr/lib/heartbeat/drbd-peer-outdater";
       }
     }

Finally, set the `fencing' option on your DRBD configured resources:

     resource my-resource {
       disk {
         fencing    resource-only;
       }
     }

Now reload your DRBD configuration:

     root-shell> drbdadmin adjust all

You can test the system by unplugging your DRBD link and monitoring the
output from `/proc/drbd'.


File: manual.info,  Node: ha-heartbeat-errors,  Prev: ha-heartbeat-drbd-dopd,  Up: ha-heartbeat

14.2.4 Dealing with System Level Errors
---------------------------------------

Because a kernel panic or oops may indicate potential problem with your
server, you should configure your server to remove itself from the
cluster in the event of a problem. Typically on a kernel panic your
system will automatically trigger a hard reboot. For a kernel oops a
reboot may not happen automatically, but the issue that caused that
oops may still lead to potential problems.

You can force a reboot by setting the `kernel.panic' and
`kernel.panic_on_oops' parameters of the kernel control file
`/etc/sysctl.conf'. For example:

      kernel.panic_on_oops = 1
      kernel.panic = 1

You can also set these parameters during runtime by using the `sysctl'
command. You can either specify the parameters on the command line:

     shell> sysctl -w kernel.panic=1

Or you can edit your `sysctl.conf' file and then reload the
configuration information:

     shell> sysctl -p

By setting both these parameters to a positive value (actually the
number of seconds to wait before triggering the reboot), the system
will reboot. Your second heartbeat node should then detect that the
server is down and then switch over to the failover host.


File: manual.info,  Node: ha-vm,  Next: ha-zfs-replication,  Prev: ha-heartbeat,  Up: ha-overview

14.3 MySQL and Virtualization
=============================

* Menu:

* ha-vm-commonissues::           Common Issues with Virtualization
* ha-vm-aws::                    Using MySQL within an Amazon EC2 Instance
* ha-vm-resources::              Virtualization Resources

Using virtualization can be an effective way of better utilizing the
hardware of your machine when using MySQL, or to provide improved
security or isolation of different instances of MySQL on the same
machine. In some circumstances, virtualization may be a suitable
solution for scaling out your database environment by enabling you to
easily deploy additional instances of a pre-configured MySQL server and
application environment to new virtualization hosts.

With any virtualization solution there is often a tradeoff between the
flexibility and ease of deployment and performance, or between the
potential performance advantage and complexities of effectively
configuring multiple instances of MySQL to reside within a single
physical host.

Different issues are experienced according to the virtualization
environment you are using. Virtualization generally falls into one of
the following categories:

   * *Native virtualization*, including products like VMware
     Workstation, Parallels Desktop/Parallels Workstation, Microsoft
     Virtual PC and VirtualBox, all work by acting as an application
     that runs within an existing operating system environment. Recent
     versions can take advantage of the virtualization extensions in
     the Intel and AMD CPUs to help improve performance.

     The application-based solutions have a number of advantages,
     including the ability to prioritize CPU usage (including multiple
     CPUs) and easily run multiple virtualized environments
     simultaneously.

     With these solutions, you also have the ability to easily create a
     virtualized environment that can be packaged and shared among
     different virtualization hosts. For example, you can create a
     MySQL environment and configuration that can be deployed multiple
     times to help extend an existing scalability or HA environment.

     The major disadvantage of this type of virtualization environment
     is the effect of the host on the performance of the virtualization
     instances. Disk storage is typically provided by using one or more
     files on the host OS which are then emulated to provide physical
     disks within the virtual instance. Other resources on the host are
     similarly shared, including CPU, network interfaces and additional
     devices (USB). It is also difficult to directly share lower-level
     components, such as PCI devices and that the ability to take
     advantage of RAID storage solutions.

   * *Paravirtualization (Hypervisor)*, including Xen, Solaris xVM
     (based on Xen), VMware ESX Server, Windows Server 2008 Hyper-V, and
     Solaris Logical Domains (LDOM), work by running a specialized
     version of the host operating system. The host OS then allows
     slightly modified versions of different operating systems to run
     within the virtualized environment.

     With paravirtualization, the level of performance and the control
     over the underlying hardware used to support the virtualized
     environments is higher than native virtualization solutions. For
     example, using paravirtualization you can dedicate individual CPU
     cores, RAM, disk drives and even PCI devices to be accessible to
     individual and specific virtual instances.

     For example, within a paravirtualized environment you could
     dedicate a physical disk drive or subsystem to a particular
     virtual environment and gain a performance benefit over a typical
     file-based solution virtual disk.

   * *Operating system-level virtualization*, including BSD jails, and
     Solaris Containers/Zones, offer methods for isolating different
     instances of an operating system environment while sharing the
     same hardware environment. Unlike the other virtualization
     solutions, operating system level virtualization is not normally
     used to run other operating systems, but instead to provide a
     level of security isolation and resource control within the core
     operating environment.

     The isolation of these different instances is the key advantage of
     this type of virtualization. Each virtualized instance sees its
     environment as if it were completely different system. The
     solution can be an effective method to provide isolated computing
     resources for different departments or users, or to provide unique
     instances for testing and development.

The main reasons for using virtualization, particularly with a database
or an application stack that includes a database component, include:

   * *Security* -- separate instances of different operating systems
     running within a single host but with effective isolation from
     each other. When used with MySQL, you can provide an increased
     level of security between different instances of each server.

   * *Consolidation* -- merging a number of individual systems with a
     relatively small load onto a single, larger, server. This can help
     reduce footprint and energy costs, or make more efficient use of a
     larger machine.  Performance is the main issue with this solution
     as the load of many MySQL databases running in individual virtual
     instances on a single machine can be considerable.

   * *Development/QA/Testing* -- by creating different instances of
     different environments and operating systems you can test your
     MySQL-based application in different environments.

   * *Scalability* -- although using virtualization imposes a
     performance hit, many virtualization solutions allow you to create
     a packaged version of an environment, including MySQL and the
     other application components. By distributing the virtualization
     environment package to new hosts you can often very quickly scale
     out by adding new hosts and deploying the virtualized environment.

The remainder of this chapter looks at common issues with using MySQL
in a virtualized environment and tips for using MySQL within different
virtualization tools.

For advice on common issues and problems, including performance and
configuration issues, when using virtualized instances, see *Note
ha-vm-commonissues::.


File: manual.info,  Node: ha-vm-commonissues,  Next: ha-vm-aws,  Prev: ha-vm,  Up: ha-vm

14.3.1 Common Issues with Virtualization
----------------------------------------

* Menu:

* ha-vm-commonissues-performance::  Virtualization Performance Issues
* ha-vm-commonissues-storage::   Virtualization Storage Issues
* ha-vm-commonissues-networking::  Virtualization Networking Issues

There are many issues related to using MySQL within a virtualized
environment that are common across the different virtualization types.
Most are directly related to the performance or security of the
environment in which you are deploying the MySQL server compared to the
host on which you are running the virtualization solution.

Before deciding to use virtualization as a solution for your database,
you should ensure that the expected load for the server and the
expected performance when run in a virtualized environment meet your
needs and requirements.

To help you determine the issues and some of the potential solutions,
use the following sections:

   * For general performance issues, problems and the probable causes,
     see *Note ha-vm-commonissues-performance::.

   * Disk and storage concerns directly affect database storage because
     most database access is limited by the I/O bandwidth.  For some
     examples and issues, see *Note ha-vm-commonissues-storage::.

   * Issues related to network configuration and performance may need
     more careful planning, especially if you are using
     network-specific technologies such as MySQL replication. For
     further examples and details, see *Note
     ha-vm-commonissues-networking::.


File: manual.info,  Node: ha-vm-commonissues-performance,  Next: ha-vm-commonissues-storage,  Prev: ha-vm-commonissues,  Up: ha-vm-commonissues

14.3.1.1 Virtualization Performance Issues
..........................................

Often the biggest consideration is the performance of a virtualized
environment once hosted. In most cases, the virtualized environment
involves some level of emulation of one or more of the hardware
interfaces (CPU, network or disk) of the host environment. The effect
is to reduce the effective performance of the virtualized environment
compared to running an application natively on the host.

Some core resourcing issues to be aware of include:

   * Using virtualization does not reduce the amount of CPU required to
     support a particular application or environment.  If your
     application stack requires 2GB of RAM on an individual machine,
     the same RAM requirement will apply within your virtualized
     environment. The additional overhead of the virtualization layer
     and host operating system or environment often mean that you will
     need 2.5GB or 3GB of RAM to run the same application within the
     virtualized environment.

     You should configure your virtualization environment with the
     correct RAM allocation according to your applications needs, and
     not to maximize the number of virtualized environments that you
     can execute within the virtualization host.

   * Virtualization of the CPU resources is more complex. If your MySQL
     database and application stack do not have a high CPU load, then
     consolidating multiple environments onto a single host is often
     more efficient. You should keep in mind that at peak times your
     application and database CPU requirement may need to grow beyond
     your default allocation.

     With some virtualization environments (Xen, Solaris Containers,
     Solaris LDOMs) you can dedicate CPU or core to a virtual instance.
     You should use this functionality to improve performance for
     database or application loads that have a high constant CPU
     requirement as the performance benefit will outweigh the
     flexibility of dynamic allocation of the CPU resources.

   * Contention of resources within the host should be taken into
     account. In a system with high CPU loads, even when dedicating RAM
     and CPU resources, the I/O channels and interfaces to storage and
     networking resources may exceed the capacity of the host.
     Solutions such as Xen and Solaris LDOMs dedicate specific
     resources to individual virtual instances, but this will not
     eliminate the effects of the overall load on the host.

   * If your database application is time sensitive, including logging
     and real-time database applications, or you are using MySQL
     Cluster, then the effects of virtualization may severely reduce
     the performance of your application. Because of the way the
     virtualized instances are executed and shared between CPUs and the
     effects of load on other resources, the response times for your
     database or application may be much higher than normal. This is
     especially true if you are running a large number of virtualized
     instances on a single host.

   * Be aware of the limitation of using a single host to run multiple
     virtualized instances. In the event of a machine or component
     failure, the problem will affect more than just one database
     instance. For example, a failure in a storage device could bring
     down all your virtualized instances.  Using a RAID solution that
     supports fault tolerance (RAID levels 1,3,4,5 or 6) will help
     protect you from the effects of this.


File: manual.info,  Node: ha-vm-commonissues-storage,  Next: ha-vm-commonissues-networking,  Prev: ha-vm-commonissues-performance,  Up: ha-vm-commonissues

14.3.1.2 Virtualization Storage Issues
......................................

Due to the random I/O nature of any database solution, running MySQL
within a virtualized environment places a heavy load on the storage
solution you are using. To help keep the performance of your
virtualized solution at the highest level, you should use the following
notes to help configure your systems.

   * Some virtualization solutions allow you to use a physical disk
     directly within your virtual host as if it were a local disk. You
     should use this whenever possible to ensure that disk contention
     issues do not affect the performance of your virtual environment.

     When running multiple virtual machines, you should use an
     individual disk for each virtual instance. Using a single disk and
     multiple partitions, with each partition dedicated to a virtual
     host, will lead to the same contention issues.

   * If you are using standard file-based storage for your virtualized
     disks:

        * File-based storage is subject to fragmentation on the host
          disk. To prevent fragmentation, create a fixed-size disk
          (that is, one where the entire space for the disk file is
          preallocated) instead of a dynamic disk that will grow with
          usage. Also be prepared to defragment the disk hosting the
          files at regular intervals to reduce the fragmentation.

        * Use separate disk files for the operating system and database
          disks, and try to avoid partitioning a disk file as this
          increases the contention within the file.

        * Use a high-performance disk solution, such as RAID or SAN, to
          store the disk files for your virtualized environments. This
          will improve the performance of what is essentially a large
          single file on a physical device.

        * When running a number of different virtualized environments
          within a single host, do not use the same physical host drive
          for multiple virtual disks. Instead, spread the virtual disks
          among multiple physical disks.  Even when using a RAID
          device, be aware that each virtual host is equivalent to
          increasing the load linearly on the host RAID device.


File: manual.info,  Node: ha-vm-commonissues-networking,  Prev: ha-vm-commonissues-storage,  Up: ha-vm-commonissues

14.3.1.3 Virtualization Networking Issues
.........................................

When running multiple virtual machines on a host, you should be aware
of the networking implications of each virtualized instance. If your
host machine has only one network card, then you will be sharing the
networking throughput for all of your machines through only one card,
and this may severely limit the performance of your virtual
environments.

If possible, you should use multiple network cards to support your
virtualized instances. Depending on the expected load of each instance,
you should dedicate or spread the allocation of the virtual network
devices across these physical devices to ensure that you do not reach
saturation.

If you are using packaged virtual machines as the basis for deployment
of your MySQL database solution, you should make sure that the network
interfaces are correctly reconfigured. Some solutions duplicate the
hardware MAC address which will cause problems when you start up
additional instances of the same virtualized environment.


File: manual.info,  Node: ha-vm-aws,  Next: ha-vm-resources,  Prev: ha-vm-commonissues,  Up: ha-vm

14.3.2 Using MySQL within an Amazon EC2 Instance
------------------------------------------------

* Menu:

* ha-vm-aws-setup::              Setting Up MySQL on an EC2 AMI
* ha-vm-aws-instance::           EC2 Instance Limitations
* ha-vm-aws-deploy::             Deploying a MySQL Database Using EC2

The Amazon Elastic Compute Cloud (EC2) service provides virtual servers
that you can build and deploy to run a variety of different
applications and services, including MySQL. The EC2 service is based
around the Xen framework, supporting x86, Linux based, platforms with
individual instances of a virtual machine referred to as an Amazon
Machine Image (AMI). You have complete (root) access to the AMI
instance that you create, allowing you to configure and install your
AMI in any way you choose.

To use EC2, you create an AMI based on the configuration and
applications that you want to use and upload the AMI to the Amazon
Simple Storage Service (S3). From the S3 resource, you can deploy one
or more copies of the AMI to run as an instance within the EC2
environment. The EC2 environment provides management and control of the
instance and contextual information about the instance while it is
running.

Because you can create and control the AMI, the configuration, and the
applications, you can deploy and create any environment you choose.
This includes a basic MySQL server in addition to more extensive
replication, HA and scalability scenarios that enable you to take
advantage of the EC2 environment, and the ability to deploy additional
instances as the demand for your MySQL services and applications grow.

To aid the deployment and distribution of work, three different Amazon
EC2 instances are available, small (identified as `m1.small'), large
(`m1.large') and extra large (`m1.xlarge'). The different types provide
different levels of computing power measured in EC2 computer units
(ECU). A summary of the different instance configurations is shown here.

                   Small              Large              Extra Large
Platform           32-bit             64-bit             64-bit
CPU cores          1                  2                  4
ECUs               1                  4                  8
RAM                1.7GB              7.5GB              15GB
Storage            150GB              840GB              1680GB
I/O Performance    Medium             High               High

The typical model for deploying and using MySQL within the EC2
environment is to create a basic AMI that you can use to hold your
database data and application. Once the basic environment for your
database and application has been created you can then choose to deploy
the AMI to a suitable instance. Here the flexibility of having an AMI
that can be re-deployed from the small to the large or extra large EC2
instance makes it easy to upgrade the hardware environment without
rebuilding your application or database stack.

To get started with MySQL on EC2, including information on how to set
up and install MySQL within an EC2 installation and how to port and
migrate your data to the running instance, see *Note ha-vm-aws-setup::.

For tips and advice on how to create a scalable EC2 environment using
MySQL, including guides on setting up replication, see *Note
ha-vm-aws-deploy::.


File: manual.info,  Node: ha-vm-aws-setup,  Next: ha-vm-aws-instance,  Prev: ha-vm-aws,  Up: ha-vm-aws

14.3.2.1 Setting Up MySQL on an EC2 AMI
.......................................

There are many different ways of setting up an EC2 AMI with MySQL,
including using any of the pre-configured AMIs supplied by Amazon.

The default _Getting Started_ AMI provided by Amazon uses Fedora Core
4, and you can install MySQL by using `yum':

     shell> yum install mysql

This will install both the MySQL server and the Perl DBD::mysql driver
for the Perl DBI API.

Alternatively, you can use one of the AMIs that include MySQL within
the standard installation.

Finally, you can also install a standard version of MySQL downloaded
from the MySQL website. The installation process and instructions are
identical to any other installation of MySQL on Linux. See *Note
installing::.

The standard configuration for MySQL places the data files in the
default location, `/var/lib/mysql'. The default data directory on an
EC2 instance is `/mnt' (although on the large and extra large instance
you can alter this configuration). You must edit `/etc/my.cnf' to set
the `datadir' option to point to the larger storage area.

*Important*:

The first time you use the main storage location within an EC2 instance
it needs to be initialized. The initialization process starts
automatically the first time you write to the device. You can start
using the device right away, but the write performance of the new
device is significantly lower on the initial writes until the
initialization process has finished.

To avoid this problem when setting up a new instance, you should start
the initialization process before populating your MySQL database. One
way to do this is to use `dd' to write to the file system:

     root-shell> dd if=/dev/zero of=initialize bs=1024M count=50

The preceding will create a 50GB on the file system and start the
initialization process. You should delete the file once the process has
finished.

The initialization process can be time-consuming. On the small
instance, initialization will take between two and three hours. For the
large and extra large drives, the initialization will be 10 or 20
hours, respectively.

In addition to configuring the correct storage location for your MySQL
data files, you should also consider setting the following other
settings in your instance before you save the instance configuration
for deployment:

   * Set the MySQL server ID so that when you use it for replication
     the ID information is set correctly.

   * Enabling binary logging so that replication can be initialized
     without starting and stopping the server.

   * Set the caching and memory parameters for your storage engines.
     There are no limitations or restrictions on what storage engines
     you use in your EC2 environment. Choose a configuration, possibly
     using one of the standard configurations provided with MySQL
     appropriate for the instance on which you expect to deploy. The
     large and extra large instances have RAM that can be dedicated to
     caching.  Be aware that if you choose to install `memcached' on
     the servers as part of your application stack you must ensure
     there is enough memory for both MySQL and `memcached'.

Once you have configured your AMI with MySQL and the rest of your
application stack, you should save the AMI so that you can deploy and
reuse the instance.

Once you have your application stack configured in an AMI, populating
your MySQL database with data should be performed by creating a dump of
your database using `mysqldump', transferring the dump to the EC2
instance, and then reloading the information into the EC2 instance
database.

Before using your instance with your application in a production
situation you should be aware of the limitations of the EC2 instance
environment. See *Note ha-vm-aws-instance::.  To begin using your MySQL
AMI, you should consult the notes on deployment. See *Note
ha-vm-aws-deploy::.


File: manual.info,  Node: ha-vm-aws-instance,  Next: ha-vm-aws-deploy,  Prev: ha-vm-aws-setup,  Up: ha-vm-aws

14.3.2.2 EC2 Instance Limitations
.................................

There are some limitations of the EC2 instances that you should be
aware of before deploying your applications. Although these shouldn't
affect your ability to deploy within the Amazon EC2 environment, they
may alter the way you setup and configure your environment to support
your application.

   * Data stored within instances is not persistent. If you create an
     instance and populate the instance with data, then the data will
     only remain in place while the machine is running. The data will
     survive a reboot. If you shut down the instance, any data it
     contained will be lost.

     To ensure that you do not lose information, take regular backups
     using *Note `mysqldump': mysqldump. If the data being stored is
     critical, consider using replication to keep a `live' backup of
     your data in the event of a failure. When creating a backup, write
     the data to the Amazon S3 service to avoid the transfer charges
     applied when copying data offsite.

   * EC2 instances are not persistent. If the hardware on which an
     instance is running fails, then the instance will be shut down.
     This can lead to loss of data or service.

   * If you want to use replication with your EC2 instances to a
     non-EC2 environment, be aware of the transfer costs to and from
     the EC2 service. Data transfer between different EC2 instances is
     free, so using replication within the EC2 environment does not
     incur additional charges.

   * Certain HA features are either not directly supported, or have
     limiting factors or problems that may reduce their utility. For
     example, using DRBD or MySQL Cluster may not work. The default
     storage configuration is also not redundant. You can use
     software-based RAID to improve redundancy, but this implies a
     further performance hit.


File: manual.info,  Node: ha-vm-aws-deploy,  Prev: ha-vm-aws-instance,  Up: ha-vm-aws

14.3.2.3 Deploying a MySQL Database Using EC2
.............................................

Because you cannot guarantee the uptime and availability of your EC2
instances, when deploying MySQL within the EC2 environment you should
use an approach that enables you to easily distribute work among your
EC2 instances. There are a number of ways of doing this. Using sharding
techniques, where you split the application across multiple servers
dedicating specific blocks of your dataset and users to different
servers is an effective way of doing this. As a general rule, it is
easier to create more EC2 instances to support more users than to
upgrade the instance to a larger machine.

The EC2 architecture means that you should treat the EC2 instances as
temporary, cache-based solutions, rather than as a long-term, high
availability solution. In addition to using multiple machines, you
should also take advantage of other services, such as `memcached' to
provide additional caching for your application to help reduce the load
on the MySQL server so that it can concentrate on writes. On the large
and extra large instances within EC2, the RAM available can be used to
provide a large memory cache for data.

Most types of scale out topology that you would use with your own
hardware can be used and applied within the EC2 environment.  However,
you should be use the limitations and advice already given to ensure
that any potential failures do not lose you any data. Also, because the
relative power of each EC2 instance is so low, you should be prepared
to alter your application to use sharding and add further EC2 instances
to improve the performance of your application.

For example, take the typical scale-out environment shown following,
where a single master replicates to one or more slaves (three in this
example), with a web server running on each replication slave.

Typical standard scale out structure

You can reproduce this structure completely within the EC2 environment,
using an EC2 instance for the master, and one instance for each of the
web and MySQL slave servers.

*Note*:

Within the EC2 environment, internal (private) IP addresses used by the
EC2 instances are constant. You should always use these internal
addresses and names when communicating between instances. Only use
public IP addresses when communicating with the outside world - for
example, when publicizing your application.

To ensure reliability of your database, you should add at least one
replication slave dedicated to providing an active backup and storage
to the Amazon S3 facility. You can see an example of this in the
following topology.

Typical standard scale out structure with backup using EC2

*Using `memcached'* within your EC2 instances should provide better
performance. The large and extra large instances have a significant
amount of RAM. To use `memcached' in your application, when loading
information from the database, first check whether the item exists in
the cache. If the data you are looking for exists in the cache, use it.
If not, reload the data from the database and populate the cache.

*Sharding* divides up data in your entire database by allocating
individual machines or machine groups to provide a unique set of data
according to an appropriate group. For example, you might put all users
with a surname ending in the letters A-D onto a single server. When a
user connects to the application and their surname is known, queries
can be redirected to the appropriate MySQL server.

When using sharding with EC2 you should separate the web server and
MySQL server into separate EC2 instances, and then apply the sharding
decision logic into your application. Once you know which MySQL server
you should be using for accessing the data you then distribute queries
to the appropriate server. You can see a sample of this in the
following illustration.

Using sharding in EC2 to spread the load

*Warning*:

With sharding and EC2 you should be careful that the potential for
failure of an instance does not affect your application.  If the EC2
instance that provides the MySQL server for a particular shard fails,
then all of the data on that shard will be unavailable.


File: manual.info,  Node: ha-vm-resources,  Prev: ha-vm-aws,  Up: ha-vm

14.3.3 Virtualization Resources
-------------------------------

For more information on virtualization, see the following links:

   * MySQL Virtualization Forum (http://forums.mysql.com/list.php?149)

   * Amazon Elastic Compute Cloud (Amazon EC2)
     (http://aws.amazon.com/ec2)

   * MySQL and Cloud Computing
     (http://www.mysql.com/products/enterprise/cloud.html)

   * MySQL Enterprise for Amazon EC2
     (http://www.mysql.com/products/enterprise/ec2.html)


File: manual.info,  Node: ha-zfs-replication,  Next: ha-memcached,  Prev: ha-vm,  Up: ha-overview

14.4 Using ZFS Replication
==========================

* Menu:

* ha-zfs-config::                Using ZFS for Filesystem Replication
* ha-zfs-mysql::                 Configurating MySQL for ZFS Replication
* ha-zfs-mysql-recovery::        Handling MySQL Recovery with ZFS

To support high availability environments, providing an instant copy of
the information on both the currently active machine and the hot backup
is a critical part of the HA solution. There are many solutions to this
problem, including *Note replication:: and *Note ha-drbd::.

The ZFS filesystem provides functionality that allows you to create a
snapshot of the filesystem contents and to then transfer the snapshot
to another machine and extract the snapshot to recreate the filesystem.
You can create a snapshot at any time, and you can create as many
snapshots as you like. By continually creating, transferring and
restoring snapshots you can provide synchronization between one ore
more machines in a fashion similar to DRBD.

To understand the replication solution within ZFS, you must first
understand the ZFS environment. Below is a simple OpenSolaris system
running with two pools, the `root' pool and another pool mounted at
`/opt':

     Filesystem             size   used  avail capacity  Mounted on
     rpool/ROOT/opensolaris-1
                            7.3G   3.6G   508M    88%    /
     /devices                 0K     0K     0K     0%    /devices
     /dev                     0K     0K     0K     0%    /dev
     ctfs                     0K     0K     0K     0%    /system/contract
     proc                     0K     0K     0K     0%    /proc
     mnttab                   0K     0K     0K     0%    /etc/mnttab
     swap                   465M   312K   465M     1%    /etc/svc/volatile
     objfs                    0K     0K     0K     0%    /system/object
     sharefs                  0K     0K     0K     0%    /etc/dfs/sharetab
     /usr/lib/libc/libc_hwcap1.so.1
                            4.1G   3.6G   508M    88%    /lib/libc.so.1
     fd                       0K     0K     0K     0%    /dev/fd
     swap                   466M   744K   465M     1%    /tmp
     swap                   465M    40K   465M     1%    /var/run
     rpool/export           7.3G    19K   508M     1%    /export
     rpool/export/home      7.3G   1.5G   508M    75%    /export/home
     rpool                  7.3G    60K   508M     1%    /rpool
     rpool/ROOT             7.3G    18K   508M     1%    /rpool/ROOT
     opt                    7.8G   1.0G   6.8G    14%    /opt

The MySQL data will be stored in a directory on `/opt'. To help
demonstrate some of the basic replication functionality, there are also
other items stored in `/opt' as well:

     total 17
     drwxr-xr-x  31 root     bin           50 Jul 21 07:32 DTT/
     drwxr-xr-x   4 root     bin            5 Jul 21 07:32 SUNWmlib/
     drwxr-xr-x  14 root     sys           16 Nov  5 09:56 SUNWspro/
     drwxrwxrwx  19 1000     1000          40 Nov  6 19:16 emacs-22.1/

To create a snapshot of the filesystem, you use `zfs snapshot', and
then specify the pool and the snapshot name:

     root-shell> zfs snapshot opt@snap1

To get a list of snapshots already taken:

     root-shell> zfs list -t snapshot
     NAME                                         USED  AVAIL  REFER  MOUNTPOINT
     opt@snap1                                       0      -  1.03G  -
     rpool@install                               19.5K      -    55K  -
     rpool/ROOT@install                            15K      -    18K  -
     rpool/ROOT/opensolaris-1@install            59.8M      -  2.22G  -
     rpool/ROOT/opensolaris-1@opensolaris-1       100M      -  2.29G  -
     rpool/ROOT/opensolaris-1/opt@install            0      -  3.61M  -
     rpool/ROOT/opensolaris-1/opt@opensolaris-1      0      -  3.61M  -
     rpool/export@install                          15K      -    19K  -
     rpool/export/home@install                     20K      -    21K  -

The snapshots themselves are stored within the filesystem metadata, and
the space required to keep them will vary as time goes on because of
the way the the snapshots are created. The initial creation of a
snapshot is really quick, because instead of taking an entire copy of
the data and metadata required to hold the entire snapshot, ZFS merely
records the point in time and metadata of when the snaphot was created.

As more changes to the original filesystem are made, the size of the
snapshot increases because more space is required to keep the record of
the old blocks. Furthermore, if you create lots of snapshots, say one
per day, and then delete the snapshots from earlier in the week, the
size of the newer snapshots may also increase, as the changes that make
up the newer state have to be included in the more recent snapshots,
rather than being spread over the seven snapshots that make up the week.

The only issue, from a backup perspective, is that snaphots exist
within the confines of the original filesystem. To get the snapshot out
into a format that you can copy to another filesystem, tape, etc. you
use the `zfs send' command to create a stream version of the snapshot.

For example, to write out the snapshot to a file:

     root-shell> zfs send opt@snap1 >/backup/opt-snap1

Or tape:

     root-shell> zfs send opt@snap1 >/dev/rmt/0

You can also write out the incremental changes between two snapshots
using `zfs send':

     root-shell> zfs send opt@snap1 opt@snap2 >/backup/opt-changes

To recover a snapshot, you use `zfs recv' which applies the snapshot
information either to a new filesytem, or to an existing one.


File: manual.info,  Node: ha-zfs-config,  Next: ha-zfs-mysql,  Prev: ha-zfs-replication,  Up: ha-zfs-replication

14.4.1 Using ZFS for Filesystem Replication
-------------------------------------------

Because `zfs send' and `zfs recv' use streams to exchange data, you can
use them to replicate information from one system to another by
combining `zfs send', `ssh', and `zfs recv'.

For example, if a snapshot of the `opt' filesystem has been created and
this needs to be copied to a new system or filesystem called
`slavepool'. You would use the following command, combining the
snapshot of `opt', the transmission to the slave machine (using `ssh'),
and the recovery of the snapshot on the slave using `zfs revc':

     root-shell> zfs send opt@snap1 |ssh mc@slave pfexec zfs recv -F slavepool

The first part, `zfs send opt@snap1', streams the snapshot, the second,
`ssh mc@slave', and the third, `pfexec zfs recv -F slavepool', receives
the streamed snapshot data and writes it to slavepool. In this
instance, I've specified the `-F' option which forces the snapshot data
to be applied, and is therefore destructive. This is fine, as I'm
creating the first version of my replicated filesystem.

On the slave machine, the replicated filesystem contains the exact same
content:

     root-shell> ls -al /slavepool/
     total 23
     drwxr-xr-x   6 root     root           7 Nov  8 09:13 ./
     drwxr-xr-x  29 root     root          34 Nov  9 07:06 ../
     drwxr-xr-x  31 root     bin           50 Jul 21 07:32 DTT/
     drwxr-xr-x   4 root     bin            5 Jul 21 07:32 SUNWmlib/
     drwxr-xr-x  14 root     sys           16 Nov  5 09:56 SUNWspro/
     drwxrwxrwx  19 1000     1000          40 Nov  6 19:16 emacs-22.1/

Once a snapshot has been created, to synchronize the filesystem again,
you need to create a new snapshot, and then use the incremental
snapshot feature of `zfs send' to send the changes between the two
snapshots to the slave machine again:

     root-shell> zfs send -i opt@snapshot1 opt@snapshot2 |ssh mc@192.168.0.93 pfexec zfs recv slavepool

Without further modification, this operation will fail. The reason is
that the filesystem on the slave machine can currently be modified, and
you can't apply the incremental changes to a destination filesystem
that has changed. It is the metadata that has changed. The metadata
about the filesystem, like the last time it was accessed - in this
case, it will have been our `ls' that caused the problem.

To prevent changes on the slave filesystem, you must set the filesystem
on the slave to be read-only:

     root-shell> zfs set readonly=on slavepool

Setting `readonly' means that you cannot change the filesystem on the
slave by normal means, including the filesystem metadata. Operations
that would normally update metadata (like our `ls') will silently
perform their function without attempting to update the filesystem
state.

In essence, the slave filesystem is nothing but a static copy of the
original filesystem. However, even when configured to to be read-only,
a filesystem can have snapshots applied to it. Now the filesystem is
read only, re-run the initial copy:

     root-shell> zfs send opt@snap1 |ssh mc@slave pfexec zfs recv -F slavepool

Now you can make changes to the original filesystem and replicate them
to the slave.


File: manual.info,  Node: ha-zfs-mysql,  Next: ha-zfs-mysql-recovery,  Prev: ha-zfs-config,  Up: ha-zfs-replication

14.4.2 Configurating MySQL for ZFS Replication
----------------------------------------------

Configuring MySQL on the source filesystem is a case of creating the
data on the filesystem that you will be replicating. The configuration
file in the example below has been updated to use `/opt/mysql-data' as
the data directory, and now I can initialize the tables:

     root-shell> mysql_install_db --defaults-file=/etc/mysql/5.0/my.cnf --user=mysql

To synchronize the initial information, perform a new snapshot and then
send an incremental snapshot to the slave using `zfs send':

     root-shell> zfs snapshot opt@snap2
     root-shell> zfs send -i opt@snap1 opt@snap2|ssh mc@192.168.0.93 pfexec zfs recv slavepool

Double check that the slave has the data by looking at the MySQL data
directory on the `slavepool':

     root-shell> ls -al /slavepool/mysql-data/

Now we can start up MySQL, create some data, and then replicate the
changes using `zfs send'/` zfs recv' to the slave to synchronize the
changes.

The rate at which you perform the synchronization is dependent on your
application and environment. The limitation is the speed required to
perform the snapshot and then to send the changes over the network.

To automate the process, you should create a script that performs the
snapshot, send, and receive operation, and then use `cron' to
synchronize the changes at set times or intervals. For automated
operations, see Tim Foster's zfs replication tool
(http://blogs.sun.com/timf/entry/zfs_automatic_snapshots_now_with).


File: manual.info,  Node: ha-zfs-mysql-recovery,  Prev: ha-zfs-mysql,  Up: ha-zfs-replication

14.4.3 Handling MySQL Recovery with ZFS
---------------------------------------

When using ZFS replication to provide a constant copy of your data, you
should ensure that you can recover your tables, either manually or
automatically, in the event of a failure of the original system.

In the event of a failure, you should follow this sequence:

  1. Stop the script on the master, if it is still up and running.

  2. Set the slave filesystem to be read/write:

          root-shell> zfs set readonly=off slavepool

  3. Start up *Note `mysqld': mysqld. on the slave. If you are using
     `InnoDB', `Falcon' or `Maria' you should get auto-recovery, if it
     is needed, to make sure the table data is correct, as shown here
     when I started up from our mid-INSERT snapshot:

          InnoDB: The log sequence number in ibdata files does not match
          InnoDB: the log sequence number in the ib_logfiles!
          081109 15:59:59  InnoDB: Database was not shut down normally!
          InnoDB: Starting crash recovery.
          InnoDB: Reading tablespace information from the .ibd files...
          InnoDB: Restoring possible half-written data pages from the doublewrite
          InnoDB: buffer...
          081109 16:00:03  InnoDB: Started; log sequence number 0 1142807951
          081109 16:00:03 [Note] /slavepool/mysql-5.0.67-solaris10-i386/bin/mysqld: ready for connections.
          Version: '5.0.67'  socket: '/tmp/mysql.sock'  port: 3306  MySQL Community Server (GPL)

On MyISAM, or other tables, you may need to run `REPAIR TABLE', and you
might even have lost some information.  You should use a
recovery-capable storage engine and a regular synchronization schedule
to reduce the risk for significant data loss.


File: manual.info,  Node: ha-memcached,  Next: mysql-proxy,  Prev: ha-zfs-replication,  Up: ha-overview

14.5 Using MySQL with `memcached'
=================================

* Menu:

* ha-memcached-install::         Installing `memcached'
* ha-memcached-using::           Using `memcached'
* ha-memcached-interfaces::      `memcached' Interfaces
* ha-memcached-stats::           Getting `memcached' Statistics
* ha-memcached-faq::             `memcached' FAQ

The largest problem with scalability within a typical environment is
the speed with which you can access information. For frequently
accessed information, using MySQL can be slow because each access of
information requires execution of the SQL query and recovery of the
information from the database. This also means that queries on tables
that are locked or blocking may delay your query and reduce the speed
of recovery of information.

`memcached' is a simple, yet highly-scalable key-based cache that
stores data and objects wherever dedicated or spare RAM is available
for very quick access by applications. To use, you run `memcached' on
one or more hosts and then use the shared cache to store
objects.Because each host's RAM is storing information, the access
speed will be much faster than having to load the information from
disk. This can provide a significant performance boost in retrieving
data versus loading the data natively from a database. Also, because
the cache is just a repository for information, you can use the cache
to store any data, including complex structures that would normally
require a significant amount of effort to create, but in a ready-to-use
format, helping to reduce the load on your MySQL servers.

The typical usage environment is to modify your application so that
information is read from the cache provided by `memcached'. If the
information isn't in `memcached', then the data is loaded from the MySQL
database and written into the cache so that future requests for the
same object benefit from the cached data.

For a typical deployment layout, see *Note ha-memcached-fig-overview::.

FIGURE GOES HERE: `memcached' Architecture Overview

In the example structure, any of the clients can contact one of the
`memcached' servers to request a given key. Each client is configured
to talk to all of the servers shown in the illustration. Within the
client, when the request is made to store the information, the key used
to reference the data is hashed and this hash is then used to select
one of the `memcached' servers. The selection of the `memcached' server
takes place on the client before the server is contacted, keeping the
process lightweight.

The same algorithm is used again when a client requests the same key.
The same key will generate the same hash, and the same `memcached'
server will be selected as the source for the data. Using this method,
the cached data is spread among all of the `memcached' servers, and the
cached information is accessible from any client. The result is a
distributed, memory-based, cache that can return information,
particularly complex data and structures, much faster than natively
reading the information from the database.

The data held within a `memcached' server is never stored on disk (only
in RAM, which means there is no persistence of data), and the RAM cache
is always populated from the backing store (a MySQL database). If a
`memcached' server fails, the data can always be recovered from the
MySQL database, albeit at a slower speed than loading the information
from the cache.


File: manual.info,  Node: ha-memcached-install,  Next: ha-memcached-using,  Prev: ha-memcached,  Up: ha-memcached

14.5.1 Installing `memcached'
-----------------------------

You can build and install `memcached' from the source code directly, or
you can use an existing operating system package or installation.

*Installing `memcached' from a Binary Distribution*

To install `memcached' on a RedHat, Fedora or CentOS host, use `yum':

     root-shell> yum install memcached

To install `memcached' on a Debian or Ubuntu host, use `apt-get':

     root-shell> apt-get install memcached

To install `memcached' on a Gentoo host, use `emerge':

     root-shell> emerge install memcached

To install on OpenSolaris, use the `pkg' command to install the
`SUNWmemcached' package:

     root-shell> pkg install SUNWmemcached

You may also find `memcached' in the Coolstack project. For more
details, see `http://cooltools.sunsource.net/coolstack/'.

*Building `memcached' from Source*

On other Unix-based platforms, including Solaris, AIX, HP-UX and Mac OS
X, and Linux distributions not mentioned already, you will need to
install from source. For Linux, make sure you have a 2.6-based kernel,
which includes the improved `epoll' interface. For all platforms,
ensure that you have `libevent' 1.1 or higher installed. You can obtain
`libevent' from `libevent' web page
(http://www.monkey.org/~provos/libevent/).

You can obtain the source for `memcached' from `memcached' website
(http://www.danga.com/memcached).

To build `memcached', follow these steps:

  1. Extract the `memcached' source package:

          shell> gunzip -c memcached-1.2.5.tar.gz | tar xf -

  2. Change to the `memcached-1.2.5 directory:'

          shell> cd memcached-1.2.5

  3. Run `configure'

          shell> ./configure

     Some additional options you may want to specify to `configure':

        * `--prefix'

          If you want to specify a different installation directory,
          use the `--prefix' option:

               shell> ./configure --prefix=/opt

          The default is to use the `/usr/local' directory.

        * `--with-libevent'

          If you have installed `libevent' and `configure' cannot find
          the library, use the `--with-libevent' option to specify the
          location of the installed library.

        * `--enable-64bit'

          To build a 64-bit version of `memcached' (which will allow
          you to use a single instance with a large RAM allocation), use
          `--enable-64bit'.

        * `--enable-threads'

          To enable multi-threading support in `memcached', which will
          improve the response times on servers with a heavy load, use
          `--enable-threads'. You must have support for the POSIX
          threads within your operating system to enable thread
          support. For more information on the threading support, see
          *Note ha-memcached-using-threads::.

        * `--enable-dtrace'

          `memcached' includes a range of DTrace threads that can be
          used to monitor and benchmark a `memcached' instance. For more
          information, see *Note ha-memcached-using-dtrace::.

  4. Run `make' to build `memcached':

          shell> make

  5. Run `make install' to install `memcached':

          shell> make install


File: manual.info,  Node: ha-memcached-using,  Next: ha-memcached-interfaces,  Prev: ha-memcached-install,  Up: ha-memcached

14.5.2 Using `memcached'
------------------------

* Menu:

* ha-memcached-using-deployment::  `memcached' Deployment
* ha-memcached-using-namespaces::  Using namespaces
* ha-memcached-using-expiry::    Data Expiry
* ha-memcached-using-hashtypes::  `memcached' Distribution Types
* ha-memcached-using-dtrace::    Using `memcached' and DTrace
* ha-memcached-using-memory::    Memory allocation within `memcached'
* ha-memcached-using-threads::   `memcached' thread Support

To start using `memcached', you must start the `memcached' service on
one or more servers.  Running `memcached' sets up the server, allocates
the memory and starts listening for connections from clients.

*Note*:

You do not need to be privileged user (`root') to run `memcached'
unless you want to listen on one of the privileged TCP/IP ports (below
1024). You must, however, use a user that has not had their memory
limits restricted using `setrlimit' or similar.

To start the server, run `memcached' as a non-privileged (i.e.
non-root) user:

     shell> memcached

By default, `memcached' uses the following settings:

   * Memory allocation of 64MB

   * Listens for connections on all network interfaces, using port 11211

   * Supports a maximum of 1024 simultaneous connections

Typically, you would specify the full combination of options that you
want when starting `memcached', and normally provide a startup script
to handle the initialization of `memcached'. For example, the following
line starts `memcached' with a maximum of 1024MB RAM for the cache,
listening on port 11121 on the IP address 192.168.0.110, running has a
background daemon:

     shell> memcached -d -m 1024 -p 11121 -l 192.168.0.110

To ensure that `memcached' is started up on boot you should check the
init script and configuration parameters. On OpenSolaris, `memcached'
is controlled by SMF.  You can enable it by using:

     root-shell> svcadm enable memcached

`memcached' supports the following options:

   * `-u user'

     If you start `memcached' as `root', use the `-u' option to specify
     the user for executing `memcached':

          shell> memcached -u memcache

   * `-m memory'

     Set the amount of memory allocated to `memcached' for object
     storage. Default is 64MB.

     To increase the amount of memory allocated for the cache, use the
     `-m' option to specify the amount of RAM to be allocated (in
     megabytes). The more RAM you allocate, the more data you can store
     and therefore the more effective your cache will be.

     *Warning*:

     Do not specify a memory allocation larger than your available RAM.
     If you specify too large a value, then some RAM allocated for
     `memcached' will be using swap space, and not physical RAM. This
     may lead to delays when storing and retrieving values, because
     data will be swapped to disk, instead of storing the data directly
     in RAM.

     You can use the output of the `vmstat' command to get the free
     memory, as shown in `free' column:

          shell> vmstat
          kthr      memory            page            disk          faults      cpu
          r b w   swap  free  re  mf pi po fr de sr s1 s2 -- --   in   sy   cs us sy id
          0 0 0 5170504 3450392 2  7  2  0  0  0  4  0  0  0  0  296   54  199  0  0 100

     For example, to allocate 3GB of RAM:

          shell> memcached -m 3072

     On 32-bit x86 systems where you are using PAE to access memory
     above the 4GB limit, you will be unable to allocate RAM beyond the
     maximum process size. You can get around this by running multiple
     instances of `memcached', each listening on a different port:

          shell> memcached -m 1024 -p11211
          shell> memcached -m 1024 -p11212
          shell> memcached -m 1024 -p11213

   * `-l interface'

     Specify a network interface/address to listen for connections.
     The default is to listen on all available address (`INADDR_ANY').

          shell> memcached -l 192.168.0.110

     Support for IPv6 address support was added in `memcached' 1.2.5.

   * `-p port'

     Specify the TCP port to use for connections. Default is 18080.

          shell> memcached -p 18080

   * `-U port'

     Specify the UDP port to use for connections. Default is 0 (off).

          shell> memcached -U 18080

   * `-s socket'

     Specify a Unix socket to listen on.

     If you are running `memcached' on the same server as the clients,
     you can disable the network interface and use a local UNIX socket
     using the `-s' option:

          shell> memcached -s /tmp/memcached

     Using a UNIX socket automatically disables network support, and
     saves network ports (allowing more ports to be used by your web
     server or other process).

   * `-a mask'

     Specify the access mask to be used for the Unix socket, in octal.
     Default is 0700.

   * `-c connections'

     Specify the maximum number of simultaneous connections to the
     `memcached' service. The default is 1024.

          shell> memcached -c 2048

     You should use this option, either to reduce the number of
     connections (to prevent overloading `memcached' service) or to
     increase the number to make more effective use of the server
     running `memcached' server.

   * `-t threads'

     Specify the numnber of threads to use when processing incoming
     requests.

     By default, `memcached' is configured to use 4 concurrent threads.
     The threading improves the performance of storing and retrieving
     data in the cache, using a locking system to prevent different
     threads overwriting or updating the same values. You may want to
     increase or decrease the number of threads, use the `-t' option:

          shell> memcached -t 8

   * `-d'

     Run `memcached' as a daemon (background) process:

          shell> memcached -d

   * `-r'

     Maximize the size of the core file limit. In the event of a
     failure, this will attempt to dump the entire memory space to disk
     as a core file, up to any limits imposed by `setrlimit'.

   * `-M'

     Return an error to the client when the memory has been exhausted.
     This replaces the normal behavior of removing older items from the
     cache to make way for new items.

   * `-k'

     Lock down all paged memory.

     *Note*:

     There is a user-level limit on how much memory you may lock.
     Trying to allocate more than the available memory will fail.  You
     can set the limit for the user you started the daemon with (not
     for the `-u user' user) within the shell by using `ulimit -S -l
     NUM_KB'

   * `-v'

     Verbose mode. Prints errors and warnings while executing the main
     event loop.

   * `-vv'

     Very verbose mode. In addition to information printed by `-v',
     also prints each client command and the response.

   * `-h'

     Print the help message and exit.

   * `-i'

     Print the `memcached' and `libevent' license.

   * `-b'

     Run a managed instance.

   * `-P pidfile'

     Save the process ID of the `memcached' instance into `file'.

   * `-f'

     Set the chunk size growth factor. When allocating new memory
     chunks, the allocated size of new chunks will be determined by
     multiple the default slab size by this factor.

   * `-n bytes'

     The minimum space allocated for the key+value+flags information.
     The default is 48 bytes.

   * `-L'

     On systems that support large memory pages, enables large memory
     page use. Using large memory pages enables `memcached' to allocate
     the item cache in one large chunk, which can improve the
     performance by reducing the number misses when accessing memory.


File: manual.info,  Node: ha-memcached-using-deployment,  Next: ha-memcached-using-namespaces,  Prev: ha-memcached-using,  Up: ha-memcached-using

14.5.2.1 `memcached' Deployment
...............................

When using `memcached' you can use a number of different potential
deployment strategies and topologies. The exact strategy you use will
depend on your application and environment. When developing a system
for deploying `memcached' within your system, you should keep in mind
the following points:

   * `memcached' is only a caching mechanism. It shouldn't be used to
     store information that you cannot otherwise afford to lose and
     then load from a different location.

   * There is no security built into the `memcached' protocol. At a
     minimum you should make sure that the servers running `memcached'
     are only accessible from inside your network, and that the network
     ports being used are blocked (using a firewall or similar). If the
     information on the `memcached' servers that is being stored is any
     sensitive, then encrypt the information before storing it in
     `memcached'.

   * `memcached' does not provide any sort of failover. Because there
     is no communication between different `memcached' instances. If an
     instance fails, your application must capable of removing it from
     the list, reloading the data and then writing data to another
     `memcached' instance.

   * Latency between the clients and the `memcached' can be a problem
     if you are using different physical machines for these tasks. If
     you find that the latency is a problem, move the `memcached'
     instances to be on the clients.

   * Key length is determined by the `memcached' server. The default
     maximum key size is 250 bytes.

   * Using a single `memcached' instance, especially for multiple
     clients, is generally a bad idea as it introduces a single point
     of failure. Instead provide at least two `memcached' instances so
     that a failure can be handled appropriately. If possible, you
     should create as many `memcached' nodes as possible. When adding
     and removing `memcached' instances from a pool, the hashing and
     distribution of key/value pairs may be affected.  For information
     on how to avoid problems, see *Note ha-memcached-using-hashtypes::.


File: manual.info,  Node: ha-memcached-using-namespaces,  Next: ha-memcached-using-expiry,  Prev: ha-memcached-using-deployment,  Up: ha-memcached-using

14.5.2.2 Using namespaces
.........................

The `memcached' cache is a very simple massive key/value storage
system, and as such there is no way of compartmentalizing data
automatically into different sections.  For example, if you are storing
information by the unique ID returned from a MySQL database, then
storing the data from two different tables will run into issues because
the same ID will probably be valid in both tables.

Some interfaces provide an automated mechanism for creating
_namespaces_ when storing information into the cache. In practice,
these namespaces are merely a prefix before a given ID that is applied
every time a value is stored or retrieve from the cache.

You can implement the same basic principle by using keys that describe
the object and the unique identifier within the key that you supply
when the object is stored. For example, when storing user data, prefix
the ID of the user with `user:' or `user-'.

*Note*:

Using namespaces or prefixes only controls the keys stored/retrieved.
There is no security within `memcached', and therefore no way to enforce
that a particular client only accesses keys with a particular
namespace. Namespaces are only useful as a method of identifying data
and preventing corruption of key/value pairs.


File: manual.info,  Node: ha-memcached-using-expiry,  Next: ha-memcached-using-hashtypes,  Prev: ha-memcached-using-namespaces,  Up: ha-memcached-using

14.5.2.3 Data Expiry
....................

There are two types of data expiry within a `memcached' instance. The
first type is applied at the point when you store a new key/value pair
into the `memcached' instance. If there is not enough space within a
suitable slab to store the value, then an existing least recently used
(LRU) object is removed (evicted) from the cache to make room for the
new item.

The LRU algorithm ensures that the object that is removed is one that
is either no longer in active use or that was used so long ago that its
data is potentially out of date or of little value.  However, in a
system where the memory allocated to `memcached' is smaller than the
number of regularly used objects required in the cache you will see a
lot of expired items being removed from the cache even though they are
in active use. You use the statistics mechanism to get a better idea of
the level of evictions (expired objects). For more information, see
*Note ha-memcached-stats::.

You can change this eviction behavior by setting the `-M' command-line
option when starting `memcached'. This option forces an error to be
returned when the memory has been exhausted, instead of automatically
evicting older data.

The second type of expiry system is an explicit mechanism that you can
set when a key/value pair is inserted into the cache, or when deleting
an item from the cache. Using an expiration time can be a useful way of
ensuring that the data in the cache is up to date and in line with your
application needs and requirements.

A typical scenario for explicitly setting the expiry time might include
caching session data for a user when accessing a website. `memcached'
uses a lazy expiry mechanism where the explicit expiry time that has
been set is compared with the current time when the object is requested.
Only objects that have not expired are returned.

You can also set the expiry time when explicitly deleting an object
from the cache. In this case, the expiry time is really a timeout and
indicates the period when any attempts to set the value for a given key
are rejected.


File: manual.info,  Node: ha-memcached-using-hashtypes,  Next: ha-memcached-using-dtrace,  Prev: ha-memcached-using-expiry,  Up: ha-memcached-using

14.5.2.4 `memcached' Distribution Types
.......................................

The `memcached' client interface supports a number of different
distribution algorithms that are used in multi-server configurations to
determine which host should be used when setting or getting data from a
given `memcached' instance. When you get or set a value, a hash is
constructed from the supplied key and then used to select a host from
the list of configured servers. Because the hashing mechanism uses the
supplied key as the basis for the hash, the selected server will be the
same during both set and get operations.

For example, if you have three servers, A, B, and C, and you set the
value `myid', then the `memcached' client will create a hash based on
the ID and select server B. When the same key is requested, the same
hash is generated, and the same server, B, will be selected to request
the value.

Because the hashing mechanism is part of the client interface, not the
server interface, the hashing process and selection is very fast. By
performing the hashing on the client, it also means that if you want to
access the same data by the same ID from the same list of servers but
from different client interfaces, you must use the same or compatible
hashing mechanisms. If you do not use the same hashing mechanism then
the same data may be recorded on different servers by different
interfaces, both wasting space on your `memcached' and leading to
potential differences in the information.

*Note*:

One way to use a multi-interface compatible hashing mechanism is to use
the `libmemcached' library and the associated interfaces. Because the
interfaces for the different languages (including C, Ruby, Perl and
Python) are using the same client library interface, they will always
generate the same hash code from the ID.

One issue with the client-side hashing mechanism is that when using
multiple servers and extending or shrinking the list of servers that
you have configured for use with `memcached', the resulting hash may
change. For example, if you have servers A, B, and C; the computed hash
for key `myid' may equate to server B. If you add another server, D,
into this list, then computing the hash for the same ID again may
result in the selection of server D for that key.

This means that servers B and D both contain the information for key
`myid', but there may be differences between the data held by the two
instances. A more significant problem is that you will get a much
higher number of cache-misses when retrieving data as the addition of a
new server will change the distribution of keys, and this will in turn
require rebuilding the cached data on the `memcached' instances and
require an increase in database reads.

For this reason, there are two common types of hashing algorithm,
_consistent_ and _modula_.

With _consistent_ hashing algorithms, the same key when applied to a
list of servers will always use the same server to store or retrieve
the keys, even if the list of configured servers changes. This means
that you can add and remove servers from the configure list and always
use the same server for a given key. There are two types of consistent
hashing algorithms available, Ketama and Wheel. Both types are
supported by `libmemcached', and implementations are available for PHP
and Java.

There are some limitations with any consistent hashing algorithm. When
adding servers to an existing list of configured servers, then keys
will be distributed to the new servers as part of the normal
distribution. When removing servers from the list, the keys will be
re-allocated to another server within the list, which will mean that
the cache will need to be re-populated with the information. Also, a
consistent hashing algorithm does not resolve the issue where you want
consistent selection of a server across multiple clients, but where each
client contains a different list of servers. The consistency is
enforced only within a single client.

With a _modula_ hashing algorithm, the client will select a server by
first computing the hash and then choosing a server from the list of
configured servers. As the list of servers changes, so the server
selected when using a modula hashing algorithm will also change. The
result is the behavior described above; changes to the list of servers
will mean different servers are selected when retrieving data leading
to cache misses and increase in database load as the cache is re-seeded
with information.

If you use only a single `memcached' instance for each client, or your
list of `memcached' servers configured for a client never changes, then
the selection of a hashing algorithm is irrelevant, as you will not
notice the effect.

If you change your servers regularly, or you use a common set of
servers that are shared among a large number of clients, then using a
consistent hashing algorithm should help to ensure that your cache data
is not duplicated and the data is evenly distributed.


File: manual.info,  Node: ha-memcached-using-dtrace,  Next: ha-memcached-using-memory,  Prev: ha-memcached-using-hashtypes,  Up: ha-memcached-using

14.5.2.5 Using `memcached' and DTrace
.....................................

`memcached' includes a number of different DTrace probes that can be
used to monitor the operation of the server. The probes included can
monitor individual connections, slab allocations, and modifications to
the hash table when a key/value pair is added, updated, or removed.

For more information on DTrace and writing DTrace scripts, read the
DTrace User Guide (http://docs.sun.com/app/docs/doc/819-5488?l=en).

Support for DTrace probes was added to `memcached' 1.2.6 includes a
number of DTrace probes that can be used to help monitor your
application. DTrace is supported on Solaris 10, OpenSolaris, Mac OS X
10.5 and FreeBSD. To enable the DTrace probes in `memcached', you
should build from source and use the `--enable-dtrace' option. For more
information, see *Note ha-memcached-install::.

The probes supported by `memcached' are:

   * `conn-allocate(connid)'

     Fired when a connection object is allocated from the connection
     pool.

        * `connid' -- the connection id

   * `conn-release(connid)'

     Fired when a connection object is released back to the connection
     pool.

     Arguments:

        * `connid' -- the connection id

   * `conn-create(ptr)'

     Fired when a new connection object is being created (i.e.  there
     are no free connection objects in the connection pool).

     Arguments:

        * `ptr' -- pointer to the connection object

   * `conn-destroy(ptr)'

     Fired when a connection object is being destroyed.

     Arguments:

        * `ptr' -- pointer to the connection object

   * `conn-dispatch(connid, threadid)'

     Fired when a connection is dispatched from the main or
     connection-management thread to a worker thread.

     Arguments:

        * `connid' -- the connection id

        * `threadid' -- the thread id

   * `slabs-allocate(size, slabclass, slabsize, ptr)'

     Allocate memory from the slab allocator

     Arguments:

        * `size' -- the requested size

        * `slabclass' -- the allocation will be fulfilled in this class

        * `slabsize' -- the size of each item in this class

        * `ptr' -- pointer to allocated memory

   * `slabs-allocate-failed(size, slabclass)'

     Failed to allocate memory (out of memory)

     Arguments:

        * `size' -- the requested size

        * `slabclass' -- the class that failed to fulfill the request

   * `slabs-slabclass-allocate(slabclass)'

     Fired when a slab class needs more space

     Arguments:

        * `slabclass' -- class that needs more memory

   * `slabs-slabclass-allocate-failed(slabclass)'

     Failed to allocate memory (out of memory)

     Arguments:

        * `slabclass' -- the class that failed grab more memory

   * `slabs-free(size, slabclass, ptr)'

     Release memory

     Arguments:

        * `size' -- the size of the memory

        * `slabclass' -- the class the memory belongs to

        * `ptr' -- pointer to the memory to release

   * `assoc-find(key, depth)'

     Fired when the when we have searched the hash table for a named
     key. These two elements provide an insight in how well the hash
     function operates. Traversals are a sign of a less optimal
     function, wasting cpu capacity.

     Arguments:

        * `key' -- the key searched for

        * `depth' -- the depth in the list of hash table

   * `assoc-insert(key, nokeys)'

     Fired when a new item has been inserted.

     Arguments:

        * `key' -- the key just inserted

        * `nokeys' -- the total number of keys currently being stored,
          including the key for which insert was called.

   * `assoc-delete(key, nokeys)'

     Fired when a new item has been removed.

     Arguments:

        * `key' -- the key just deleted

        * `nokeys' -- the total number of keys currently being stored,
          excluding the key for which delete was called.

   * `item-link(key, size)'

     Fired when an item is being linked in the cache

     Arguments:

        * `key' -- the items key

        * `size' -- the size of the data

   * `item-unlink(key, size)'

     Fired when an item is being deleted

     Arguments:

        * `key' -- the items key

        * `size' -- the size of the data

   * `item-remove(key, size)'

     Fired when the refcount for an item is reduced

     Arguments:

        * `key' -- the items key

        * `size' -- the size of the data

   * `item-update(key, size)'

     Fired when the "last referenced" time is updated

     Arguments:

        * `key' -- the items key

        * `size' -- the size of the data

   * `item-replace(oldkey, oldsize, newkey, newsize)'

     Fired when an item is being replaced with another item

     Arguments:

        * `oldkey' -- the key of the item to replace

        * `oldsize' -- the size of the old item

        * `newkey' -- the key of the new item

        * `newsize' -- the size of the new item

   * `process-command-start(connid, request, size)'

     Fired when the processing of a command starts

     Arguments:

        * `connid' -- the connection id

        * `request' -- the incoming request

        * `size' -- the size of the request

   * `process-command-end(connid, response, size)'

     Fired when the processing of a command is done

     Arguments:

        * `connid' -- the connection id

        * `respnse' -- the response to send back to the client

        * `size' -- the size of the response

   * `command-get(connid, key, size)'

     Fired for a get-command

     Arguments:

        * `connid' -- connection id

        * `key' -- requested key

        * `size' -- size of the key's data (or -1 if not found)

   * `command-gets(connid, key, size, casid)'

     Fired for a gets command

     Arguments:

        * `connid' -- connection id

        * `key' -- requested key

        * `size' -- size of the key's data (or -1 if not found)

        * `casid' -- the casid for the item

   * `command-add(connid, key, size)'

     Fired for a add-command

     Arguments:

        * `connid' -- connection id

        * `key' -- requested key

        * `size' -- the new size of the key's data (or -1 if not found)

   * `command-set(connid, key, size)'

     Fired for a set-command

     Arguments:

        * `connid' -- connection id

        * `key' -- requested key

        * `size' -- the new size of the key's data (or -1 if not found)

   * `command-replace(connid, key, size)'

     Fired for a replace-command

     Arguments:

        * `connid' -- connection id

        * `key' -- requested key

        * `size' -- the new size of the key's data (or -1 if not found)

   * `command-prepend(connid, key, size)'

     Fired for a prepend-command

     Arguments:

        * `connid' -- connection id

        * `key' -- requested key

        * `size' -- the new size of the key's data (or -1 if not found)

   * `command-append(connid, key, size)'

     Fired for a append-command

     Arguments:

        * `connid' -- connection id

        * `key' -- requested key

        * `size' -- the new size of the key's data (or -1 if not found)

   * `command-cas(connid, key, size, casid)'

     Fired for a cas-command

     Arguments:

        * `connid' -- connection id

        * `key' -- requested key

        * `size' -- size of the key's data (or -1 if not found)

        * `casid' -- the cas id requested

   * `command-incr(connid, key, val)'

     Fired for incr command

     Arguments:

        * `connid' -- connection id

        * `key' -- the requested key

        * `val' -- the new value

   * `command-decr(connid, key, val)'

     Fired for decr command

     Arguments:

        * `connid' -- connection id

        * `key' -- the requested key

        * `val' -- the new value

   * `command-delete(connid, key, exptime)'

     Fired for a delete command

     Arguments:

        * `connid' -- connection id

        * `key' -- the requested key

        * `exptime' -- the expiry time


File: manual.info,  Node: ha-memcached-using-memory,  Next: ha-memcached-using-threads,  Prev: ha-memcached-using-dtrace,  Up: ha-memcached-using

14.5.2.6 Memory allocation within `memcached'
.............................................

When you first start `memcached', the memory that you have configured
is not automatically allocated.  Instead, `memcached' only starts
allocating and reserving physical memory once you start saving
information into the cache.

When you start to store data into the cache, `memcached' does not
allocate the memory for the data on an item by item basis. Instead, a
slab allocation is used to optimize memory usage and prevent memory
fragmentation when information expires from the cache.

With slab allocation, memory is reserved in blocks of 1MB. The slab is
divided up into a number of blocks of equal size. When you try to store
a value into the cache, `memcached' checks the size of the value that
you are adding to the cache and determines which slab contains the
right size allocation for the item. If a slab with the item size
already exists, the item is written to the block within the slab.

If the new item is bigger than the size of any existing blocks, then a
new slab is created, divided up into blocks of a suitable size. If an
existing slab with the right block size already exists, but there are
no free blocks, a new slab is created. If you update an existing item
with data that is larger than the existing block allocation for that
key, then the key is re-allocated into a suitable slab.

For example, the default size for the smallest block is 88 bytes (40
bytes of value, and the default 48 bytes for the key and flag data). If
the size of the first item you store into the cache is less than 40
bytes, then a slab with a block size of 88 bytes is created and the
value stored.

If the size of the data that you want to store is larger than this
value, then the block size is increased by the chunk size factor until
a block size large enough to hold the value is determined. The block
size is always a function of the scale factor, rounded up to a block
size which is exactly divisible into the chunk size.

For a sample of the structure, see *Note ha-memcached-fig-slabs::.

FIGURE GOES HERE: Memory Allocation in `memcached'

The result is that you have multiple pages allocated within the range
of memory allocated to `memcached'. Each page is 1MB in size (by
default), and will be split into a different number of chunks,
according to the chunk size required to store the key/value pairs. Each
instance will have multiple pages allocated, and a page will always be
created when a new item needs to be created requiring a chunk of a
particular size.  A slab may consist of multiple pages, and each page
within a slab will contain an equal number of chunks.

The chunk size of a new slab is determined by the base chunk size
combined with the chunk size growth factor. For example, if the initial
chunks are 104 bytes in size, and the default chunk size growth factor
is used (1.25), then the next chunk size allocated would be the best
power of 2 fit for 104*1.25, or 136 bytes.

Allocating the pages in this way ensures that memory does not get
fragmented. However, depending on the distribution of the objects that
you want to store, it may lead to an inefficient distribution of the
slabs and chunks if you have significantly different sized items. For
example, having a relatively small number of items within each chunk
size may waste a lot of memory with just few chunks in each allocated
page.

You can tune the growth factor to reduce this effect by using the `-f'
command line option. This will adapt the growth factor applied to make
more effective use of the chunks and slabs allocated. For information
on how to determine the current slab allocation statistics, see *Note
ha-memcached-stats-slabs::.

If your operating system supports it, you can also start `memcached'
with the `-L' command line option. With this option enabled, it will
preallocate all the memory during startup using large memory pages.
This can improve performance by reducing the number of misses in the
CPU memory cache.


File: manual.info,  Node: ha-memcached-using-threads,  Prev: ha-memcached-using-memory,  Up: ha-memcached-using

14.5.2.7 `memcached' thread Support
...................................

If you enable the thread implementation within when building
`memcached' from source, then `memcached' will use multiple threads in
addition to the `libevent' system to handle requests.

When enabled, the the threading implementation operates as follows:

   * Threading is handled by wrapping functions within the code to
     provide basic protection from updating the same global structures
     at the same time.

   * Each thread uses its own instance of the `libevent' to help
     improve performance.

   * TCP/IP connections are handled with a single thread listening on
     the TCP/IP socket. Each connection is then distribution to one of
     the active threads on a simple round-robin basis. Each connection
     then operates solely within this thread while the connection
     remains open.

   * For UDP connections, all the threads listen to a single UDP socket
     for incoming requests. Threads that are not currently dealing with
     another request ignore the incoming packet. One of the remaining,
     non-busy, threads will read the request and send the response.
     This implementation can lead to increased CPU load as threads will
     wake from sleep to potentially process the request.

Using threads can increase the performance on servers that have
multiple CPU cores available, as the requests to update the hash table
can be spread between the individual threads. However, because of the
locking mechanism employed you may want to experiment with different
thread values to achieve the best performance based on the number and
type of requests within your given workload.


File: manual.info,  Node: ha-memcached-interfaces,  Next: ha-memcached-stats,  Prev: ha-memcached-using,  Up: ha-memcached

14.5.3 `memcached' Interfaces
-----------------------------

* Menu:

* ha-memcached-interfaces-libmemcached::  Using `libmemcached'
* ha-memcached-interfaces-perl::  Using MySQL and `memcached' with Perl
* ha-memcached-interfaces-python::  Using MySQL and `memcached' with Python
* ha-memcached-interfaces-php::  Using MySQL and `memcached' with PHP
* ha-memcached-interfaces-ruby::  Using MySQL and `memcached' with Ruby
* ha-memcached-interfaces-java::  Using MySQL and `memcached' with Java
* ha-memcached-interfaces-mysqludf::  Using the MySQL `memcached' UDFs
* ha-memcached-interfaces-protocol::  `memcached' Protocol

A number of interfaces from different languages exist for interacting
with `memcached' servers and storing and retrieving information.
Interfaces for the most common language platforms including Perl, PHP,
Python, Ruby, C and Java.

Data stored into a `memcached' server is referred to by a single string
(the key), with storage into the cache and retrieval from the cache
using the key as the reference. The cache therefore operates like a
large associative array or hash. It is not possible to structure or
otherwise organize the information stored in the cache. If you want to
store information in a structured way, you must use 'formatted' keys.

The following tips may be useful to you when using `memcached':

The general sequence for using `memcached' in any language as a caching
solution is as follows:

  1. Request the item from the cache.

  2. If the item exists, use the item data.

  3. If the item does not exist, load the data from MySQL, and store
     the value into the cache. This means the value will be available
     to the next client that requests it from the cache.

For a flow diagram of this sequence, see *Note
ha-memcached-fig-basicflow::.

FIGURE GOES HERE: Typical `memcached' Application Flowchart

The interface to `memcached' supports the following methods for storing
and retrieving information in the cache, and these are consistent
across all the different APIs, even though the language specific
mechanics may be different:

   * `get(key)' -- retrieves information from the cache. Returns the
     value if it exists, or `NULL', `nil', or `undefined' or the
     closest equivalent in the corresponding language, if the specified
     key does not exist.

   * `set(key, value [, expiry])' -- sets the key in the cache to the
     specified value. Note that this will either update an existing key
     if it already exists, or add a new key/value pair if the key
     doesn't exist. If the expiry time is specified, then the key will
     expire (be deleted) when the expiry time is reached. The time
     should be specified in seconds, and is taken as a relative time if
     the value is less than 30 days (30*24*60*60), or an absolute time
     (epoch) if larger than this value.

   * `add(key, value [, expiry])' -- adds the key to the cache, if the
     specified key doesn't already exist.

   * `replace(key, value [, expiry])' -- replace the `value' of the
     specified `key', only if the key already exists.

   * `delete(key [, time])' -- Deletes the `key' from the cache. If you
     supply a `time', then adding a value with the specified `key' is
     blocked for the specified period.

   * `incr(key [, value])' -- Increment the specified `key' by one or
     the specified `value'.

   * `decr(key [, value])' -- Decrement the specified `key' by one or
     the specified `value'.

   * `flush_all' -- invalidates (or expires) all the current items in
     the cache. Technically they will still exist (they are not
     deleted), but they will be silently destroyed the next time you
     try to access them.

In all implementations, most or all of these functions are duplicated
through the corresponding native language interface.

For all languages and interfaces, you should use `memcached' to store
full items, rather than simply caching single rows of information from
the database. For example, when displaying a record about an object
(invoice, user history, or blog post), all the data for the associated
entry should be loaded from the database, and compiled into the internal
structure that would normally be required by the application. You then
save the complete object into the cache.

Data cannot be stored directly, it needs to be serialized, and most
interfaces will serialize the data for you. Perl uses `Storable', PHP
uses `serialize', Python uses `cPickle' (or `Pickle') and Java uses the
`Serializable' interface. In most cases, the serialization interface
used is customizable. If you want to share data stored in `memcached'
instances between different language interfaces, consider using a common
serialization solution such as JSON (Javascript Object Notation).


File: manual.info,  Node: ha-memcached-interfaces-libmemcached,  Next: ha-memcached-interfaces-perl,  Prev: ha-memcached-interfaces,  Up: ha-memcached-interfaces

14.5.3.1 Using `libmemcached'
.............................

* Menu:

* ha-memcached-interfaces-libmemcached-base::  `libmemcached' Base Functions
* ha-memcached-interfaces-libmemcached-servers::  `libmemcached' Server Functions
* ha-memcached-interfaces-libmemcached-set::  `libmemcached' Set Functions
* ha-memcached-interfaces-libmemcached-get::  `libmemcached' Get Functions
* ha-memcached-interfaces-libmemcached-behaviors::  `libmemcached' Behaviors
* ha-memcached-interfaces-libmemcached-utilities::  `libmemcached' Command-line Utilities

The `libmemcached' library provides both C and C++ interfaces to
`memcached' and is also the basis for a number of different additional
API implementations, including Perl, Python and Ruby. Understanding the
core `libmemcached' functions can help when using these other
interfaces.

The C library is the most comprehensive interface library for
`memcached' and provides a wealth of functions and operational systems
not always exposed in the other interfaces not based on the
`libmemcached' library.

The different functions can be divided up according to their basic
operation. In addition to functions that interface to the core API,
there are a number of utility functions that provide extended
functionality, such as appending and prepending data.

To build and install `libmemcached', download the `libmemcached'
package, run configure, and then build and install:

     shell> tar xjf libmemcached-0.21.tar.gz
     shell> cd libmemcached-0.21
     shell> ./configure
     shell> make
     shell> make install

On many Linux operating systems, you can install the corresponding
`libmemcached' package through the usual `yum', `apt-get' or similar
commands. On OpenSolaris, use `pkg' to install the `SUNWlibmemcached'
package.

To build an application that uses the library, you need to first set
the list of servers. You can do this either by directly manipulating
the servers configured within the main `memcached_st' structure, or by
separately populating a list of servers, and then adding this list to
the `memcached_st' structure. The latter method is used in the
following example. Once the server list has been set, you can call the
functions to store or retrieve data. A simple application for setting a
preset value to localhost is provided here:

     #include <stdio.h>
     #include <string.h>
     #include <unistd.h>
     #include <libmemcached/memcached.h>

     int main(int argc, char *argv[])
     {
       memcached_server_st *servers = NULL;
       memcached_st *memc;
       memcached_return rc;
       char *key= "keystring";
       char *value= "keyvalue";

       memcached_server_st *memcached_servers_parse (char *server_strings);
       memc= memcached_create(NULL);

       servers= memcached_server_list_append(servers, "localhost", 11211, &rc);
       rc= memcached_server_push(memc, servers);

       if (rc == MEMCACHED_SUCCESS)
         fprintf(stderr,"Added server successfully\n");
       else
         fprintf(stderr,"Couldn't add server: %s\n",memcached_strerror(memc, rc));

       rc= memcached_set(memc, key, strlen(key), value, strlen(value), (time_t)0, (uint32_t)0);

       if (rc == MEMCACHED_SUCCESS)
         fprintf(stderr,"Key stored successfully\n");
       else
         fprintf(stderr,"Couldn't store key: %s\n",memcached_strerror(memc, rc));

       return 0;
     }

You can test the success of an operation by using the return value, or
populated result code, for a given function. The value will always be
set to `MEMCACHED_SUCCESS' if the operation succeeded. In the event of
a failure, use the `memcached_strerror()' function to translate the
result code into a printable string.

To build the application, you must specify the `memcached' library:

     shell> gcc -o memc_basic memc_basic.c -lmemcached

Running the above sample application, after starting a `memcached'
server, should return a success message:

     shell> memc_basic
     Added server successfully
     Key stored successfully


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-base,  Next: ha-memcached-interfaces-libmemcached-servers,  Prev: ha-memcached-interfaces-libmemcached,  Up: ha-memcached-interfaces-libmemcached

14.5.3.2 `libmemcached' Base Functions
......................................

The base `libmemcached' functions allow you to create, destroy and
clone the main `memcached_st' structure that is used to interface to
the `memcached' servers. The main functions are defined below:

     memcached_st *memcached_create (memcached_st *ptr);

Creates a new `memcached_st' structure for use with the other
`libmemcached' API functions. You can supply an existing, static,
`memcached_st' structure, or `NULL' to have a new structured allocated.
Returns a pointer to the created structure, or `NULL' on failure.

     void memcached_free (memcached_st *ptr);

Free the structure and memory allocated to a previously created
`memcached_st' structure.

     memcached_st *memcached_clone(memcached_st *clone, memcached_st *source);

Clone an existing `memcached' structure from the specified `source',
copying the defaults and list of servers defined in the structure.


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-servers,  Next: ha-memcached-interfaces-libmemcached-set,  Prev: ha-memcached-interfaces-libmemcached-base,  Up: ha-memcached-interfaces-libmemcached

14.5.3.3 `libmemcached' Server Functions
........................................

The `libmemcached' API uses a list of servers, stored within the
`memcached_server_st' structure, to act as the list of servers used by
the rest of the functions. To use `memcached', you first create the
server list, and then apply the list of servers to a valid
`libmemcached' object.

Because the list of servers, and the list of servers within an active
`libmemcached' object can be manipulated separately, you can update and
manage server lists while an active `libmemcached' interface is running.

The functions for manipulating the list of servers within a
`memcached_st' structure are given below:

     memcached_return
                memcached_server_add (memcached_st *ptr,
                                      char *hostname,
                                      unsigned int port);

Add a server, using the given `hostname' and `port' into the
`memcached_st' structure given in `ptr'.

     memcached_return
                memcached_server_add_unix_socket (memcached_st *ptr,
                                                  char *socket);

Add a Unix socket to the list of servers configured in the
`memcached_st' structure.

     unsigned int memcached_server_count (memcached_st *ptr);

Return a count of the number of configured servers within the
`memcached_st' structure.

     memcached_server_st *
                memcached_server_list (memcached_st *ptr);

Returns an array of all the defined hosts within a `memcached_st'
structure.

     memcached_return
                memcached_server_push (memcached_st *ptr,
                                       memcached_server_st *list);

Pushes an existing list of servers onto list of servers configured for
a current `memcached_st' structure. This adds servers to the end of the
existing list, and duplicates are not checked.

The `memcached_server_st' structure can be used to create a list of
`memcached' servers which can then be applied individually to
`memcached_st' structures.

     memcached_server_st *
                memcached_server_list_append (memcached_server_st *ptr,
                                              char *hostname,
                                              unsigned int port,
                                              memcached_return *error);

Add a server, with `hostname' and `port', to the server list in `ptr'.
The result code is handled by the `error' argument, which should point
to an existing `memcached_return' variable. The function returns a
pointer to the returned list.

      unsigned int memcached_server_list_count (memcached_server_st *ptr);

Return the number of the servers in the server list.

     void memcached_server_list_free (memcached_server_st *ptr);

Free up the memory associated with a server list.

     memcached_server_st *memcached_servers_parse (char *server_strings);

Parses a string containing a list of servers, where individual servers
are separated by a comma and/or space, and where individual servers are
of the form `server[:port]'. The return value is a server list
structure.


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-set,  Next: ha-memcached-interfaces-libmemcached-get,  Prev: ha-memcached-interfaces-libmemcached-servers,  Up: ha-memcached-interfaces-libmemcached

14.5.3.4 `libmemcached' Set Functions
.....................................

The set related functions within `libmemcached' provide the same
functionality as the core functions supported by the `memcached'
protocol. The full definition for the different functions is the same
for all the base functions (add, replace, prepend, append). For
example, the function definition for `memcached_set()' is:

     memcached_return
                memcached_set (memcached_st *ptr,
                               const char *key,
                               size_t key_length,
                               const char *value,
                               size_t value_length,
                               time_t expiration,
                               uint32_t flags);

The `ptr' is the `memcached_st' structure. The `key' and `key_length'
define the key name and length, and `value' and `value_length' the
corresponding value and length. You can also set the expiration and
optional flags. For more information, see *Note
ha-memcached-interfaces-libmemcached-behaviors::.

The following table outlines the remainder of the set-related functions.

`libmemcached' Function              Equivalent to
`memcached_set(memc, key,            Generic `set()' operation.
key_length, value, value_length,     
expiration, flags)'                  
`memcached_add(memc, key,            Generic `add()' function.
key_length, value, value_length,     
expiration, flags)'                  
`memcached_replace(memc, key,        Generic `replace()'.
key_length, value, value_length,     
expiration, flags)'                  
`memcached_prepend(memc, key,        Prepends the specified `value'
key_length, value, value_length,     before the current value of the
expiration, flags)'                  specified `key'.
`memcached_append(memc, key,         Appends the specified `value' after
key_length, value, value_length,     the current value of the specified
expiration, flags)'                  `key'.
`memcached_cas(memc, key,            Overwrites the data for a given key
key_length, value, value_length,     as long as the corresponding `cas'
expiration, flags, cas)'             value is still the same within the
                                     server.
`memcached_set_by_key(memc,          Similar to the generic `set()', but
master_key, master_key_length, key,  has the option of an additional
key_length, value, value_length,     master key that can be used to
expiration, flags)'                  identify an individual server.
`memcached_add_by_key(memc,          Similar to the generic `add()', but
master_key, master_key_length, key,  has the option of an additional
key_length, value, value_length,     master key that can be used to
expiration, flags)'                  identify an individual server.
`memcached_replace_by_key(memc,      Similar to the generic `replace()',
master_key, master_key_length, key,  but has the option of an additional
key_length, value, value_length,     master key that can be used to
expiration, flags)'                  identify an individual server.
`memcached_prepend_by_key(memc,      Similar to the
master_key, master_key_length, key,  `memcached_prepend()', but has the
key_length, value, value_length,     option of an additional master key
expiration, flags)'                  that can be used to identify an
                                     individual server.
`memcached_append_by_key(memc,       Similar to the
master_key, master_key_length, key,  `memcached_append()', but has the
key_length, value, value_length,     option of an additional master key
expiration, flags)'                  that can be used to identify an
                                     individual server.
`memcached_cas_by_key(memc,          Similar to the `memcached_cas()',
master_key, master_key_length, key,  but has the option of an additional
key_length, value, value_length,     master key that can be used to
expiration, flags)'                  identify an individual server.

The `by_key' methods add two further arguments, the master key, to be
used and applied during the hashing stage for selecting the servers.
You can see this in the following definition:

     memcached_return
                memcached_set_by_key(memcached_st *ptr,
                                     const char *master_key,
                                     size_t master_key_length,
                                     const char *key,
                                     size_t key_length,
                                     const char *value,
                                     size_t value_length,
                                     time_t expiration,
                                     uint32_t flags);

All the functions return a value of type `memcached_return', which you
can compare against the `MEMCACHED_SUCCESS' constant.


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-get,  Next: ha-memcached-interfaces-libmemcached-behaviors,  Prev: ha-memcached-interfaces-libmemcached-set,  Up: ha-memcached-interfaces-libmemcached

14.5.3.5 `libmemcached' Get Functions
.....................................

The `libmemcached' functions provide both direct access to a single
item, and a multiple-key request mechanism that provides much faster
responses when fetching a large number of keys simultaneously.

The main get-style function, which is equivalent to the generic `get()'
is `memcached_get()'. The functions a string pointer to the returned
value for a corresponding key.

     char *memcached_get (memcached_st *ptr,
                          const char *key, size_t key_length,
                          size_t *value_length,
                          uint32_t *flags,
                          memcached_return *error);

A multi-key get, `memcached_mget()', is also available. Using a
multiple key get operation is much quicker to do in one block than
retrieving the key values with individual calls to `memcached_get()'. To
start the multi-key get, you need to call `memcached_mget()':

     memcached_return
              memcached_mget (memcached_st *ptr,
                              char **keys, size_t *key_length,
                              unsigned int number_of_keys);

The return value is the success of the operation. The `keys' parameter
should be an array of strings containing the keys, and `key_length' an
array containing the length of each corresponding key.
`number_of_keys' is the number of keys supplied in the array.

To fetch the individual values, you need to use `memcached_fetch()' to
get each corresponding value.

     char *memcached_fetch (memcached_st *ptr,
                              const char *key, size_t *key_length,
                              size_t *value_length,
                              uint32_t *flags,
                              memcached_return *error);

The function returns the key value, with the `key', `key_length' and
`value_length' parameters being populated with the corresponding key
and length information. The function returns `NULL' when there are no
more values to be returned. A full example, including the populating of
the key data and the return of the information is provided here.

     #include <stdio.h>
     #include <sstring.h>
     #include <unistd.h>
     #include <libmemcached/memcached.h>

     int main(int argc, char *argv[])
     {
       memcached_server_st *servers = NULL;
       memcached_st *memc;
       memcached_return rc;
       char *keys[]= {"huey", "dewey", "louie"};
       size_t key_length[3];
       char *values[]= {"red", "blue", "green"};
       size_t value_length[3];
       unsigned int x;
       uint32_t flags;

       char return_key[MEMCACHED_MAX_KEY];
       size_t return_key_length;
       char *return_value;
       size_t return_value_length;

       memc= memcached_create(NULL);

       servers= memcached_server_list_append(servers, "localhost", 11211, &rc);
       rc= memcached_server_push(memc, servers);

       if (rc == MEMCACHED_SUCCESS)
         fprintf(stderr,"Added server successfully\n");
       else
         fprintf(stderr,"Couldn't add server: %s\n",memcached_strerror(memc, rc));

       for(x= 0; x < 3; x++)
         {
           key_length[x] = strlen(keys[x]);
           value_length[x] = strlen(values[x]);

           rc= memcached_set(memc, keys[x], key_length[x], values[x],
                             value_length[x], (time_t)0, (uint32_t)0);
           if (rc == MEMCACHED_SUCCESS)
             fprintf(stderr,"Key %s stored successfully\n",keys[x]);
           else
             fprintf(stderr,"Couldn't store key: %s\n",memcached_strerror(memc, rc));
         }

       rc= memcached_mget(memc, keys, key_length, 3);

       if (rc == MEMCACHED_SUCCESS)
         {
           while ((return_value= memcached_fetch(memc, return_key, &return_key_length,
                                                 &return_value_length, &flags, &rc)) != NULL)
             {
               if (rc == MEMCACHED_SUCCESS)
                 {
                   fprintf(stderr,"Key %s returned %s\n",return_key, return_value);
                 }
             }
         }

       return 0;
     }

Running the above application:

     shell> memc_multi_fetch
     Added server successfully
     Key huey stored successfully
     Key dewey stored successfully
     Key louie stored successfully
     Key huey returned red
     Key dewey returned blue
     Key louie returned green


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-behaviors,  Next: ha-memcached-interfaces-libmemcached-utilities,  Prev: ha-memcached-interfaces-libmemcached-get,  Up: ha-memcached-interfaces-libmemcached

14.5.3.6 `libmemcached' Behaviors
.................................

The behavior of `libmemcached' can be modified by setting one or more
behavior flags. These can either be set globally, or they can be
applied during the call to individual functions. Some behaviors also
accept an additional setting, such as the hashing mechanism used when
selecting servers.

To set global behaviors:

     memcached_return
                memcached_behavior_set (memcached_st *ptr,
                                        memcached_behavior flag,
                                        uint64_t data);

To get the current behavior setting:

     uint64_t
                memcached_behavior_get (memcached_st *ptr,
                                        memcached_behavior flag);

Behavior                      Description
`MEMCACHED_BEHAVIOR_NO_BLOCK' Caused `libmemcached' to use asynchronous
                              I/O.
`MEMCACHED_BEHAVIOR_TCP_NODELAY'Turns on no-delay for network sockets.
`MEMCACHED_BEHAVIOR_HASH'     Without a value, sets the default hashing
                              algorithm for keys to use MD5.  Other
                              valid values include
                              `MEMCACHED_HASH_DEFAULT',
                              `MEMCACHED_HASH_MD5', `MEMCACHED_HASH_CRC',
                              `MEMCACHED_HASH_FNV1_64',
                              `MEMCACHED_HASH_FNV1A_64',
                              `MEMCACHED_HASH_FNV1_32', and
                              `MEMCACHED_HASH_FNV1A_32'.
`MEMCACHED_BEHAVIOR_DISTRIBUTION'Changes the method of selecting the server
                              used to store a given value.  The default
                              method is `MEMCACHED_DISTRIBUTION_MODULA'.
                              You can enable consistent hashing by
                              setting
                              `MEMCACHED_DISTRIBUTION_CONSISTENT'.
                              `MEMCACHED_DISTRIBUTION_CONSISTENT' is an
                              alias for the value
                              `MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA'.
`MEMCACHED_BEHAVIOR_CACHE_LOOKUPS'Cache the lookups made to the DNS service.
                              This can improve the performance if you
                              are using names instead of IP addresses
                              for individual hosts.
`MEMCACHED_BEHAVIOR_SUPPORT_CAS'Support CAS operations. By default, this
                              is disabled because it imposes a
                              performance penalty.
`MEMCACHED_BEHAVIOR_KETAMA'   Sets the default distribution to
                              `MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA'
                              and the hash to `MEMCACHED_HASH_MD5'.
`MEMCACHED_BEHAVIOR_POLL_TIMEOUT'Modify the timeout value used by `poll()'.
                              You should supply a `signed int' pointer
                              for the timeout value.
`MEMCACHED_BEHAVIOR_BUFFER_REQUESTS'Buffers IO requests instead of them being
                              sent. A get operation, or closing the
                              connection will cause the data to be
                              flushed.
`MEMCACHED_BEHAVIOR_VERIFY_KEY'Forces `libmemcached' to verify that a
                              specified key is valid.
`MEMCACHED_BEHAVIOR_SORT_HOSTS'If set, hosts added to the list of
                              configured hosts for a `memcached_st'
                              structure will placed into the host list
                              in sorted order. This will break
                              consistent hashing if that behavior has
                              been enabled.
`MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT'In non-blocking mode this changes the
                              value of the timeout during socket
                              connection.


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-utilities,  Prev: ha-memcached-interfaces-libmemcached-behaviors,  Up: ha-memcached-interfaces-libmemcached

14.5.3.7 `libmemcached' Command-line Utilities
..............................................

In addition to the main C library interface, `libmemcached' also
includes a number of command line utilities that can be useful when
working with and debugging `memcached' applications.

All of the command line tools accept a number of arguments, the most
critical of which is `servers', which specifies the list of servers to
connect to when returning information.

The main tools are:

   * `memcat' -- display the value for each ID given on the command
     line:

          shell> memcat --servers=localhost hwkey
          Hello world

   * `memcp' -- copy the contents of a file into the cache, using the
     file names as the key:

          shell> echo "Hello World" > hwkey
          shell> memcp --servers=localhost hwkey
          shell> memcat --servers=localhost hwkey
          Hello world

   * `memrm' -- remove an item from the cache:

          shell> memcat --servers=localhost hwkey
          Hello world
          shell> memrm --servers=localhost hwkey
          shell> memcat --servers=localhost hwkey

   * `memslap' -- test the load on one or more `memcached' servers,
     simulating get/set and multiple client operations. For example, you
     can simulate the load of 100 clients performing get operations:

          shell> memslap --servers=localhost --concurrency=100 --flush --test=get
          memslap --servers=localhost --concurrency=100 --flush --test=get	Threads connecting to servers 100
          	Took 13.571 seconds to read data

   * `memflush' -- flush (empty) the contents of the `memcached' cache.

          shell> memflush --servers=localhost


File: manual.info,  Node: ha-memcached-interfaces-perl,  Next: ha-memcached-interfaces-python,  Prev: ha-memcached-interfaces-libmemcached,  Up: ha-memcached-interfaces

14.5.3.8 Using MySQL and `memcached' with Perl
..............................................

The `Cache::Memcached' module provides a native interface to the
Memcache protocol, and provides support for the core functions offered
by `memcached'. You should install the module using your hosts native
package management system. Alternatively, you can install the module
using `CPAN':

     root-shell> perl -MCPAN -e 'install Cache::Memcached'

To use `memcached' from Perl through `Cache::Memcached' module, you
first need to create a new `Cache::Memcached' object that defines the
list of servers and other parameters for the connection. The only
argument is a hash containing the options for the cache interface. For
example, to create a new instance that uses three `memcached' servers:

     use Cache::Memcached;

     my $cache = new Cache::Memcached {
         'servers' => [
             '192.168.0.100:11211',
             '192.168.0.101:11211',
             '192.168.0.102:11211',
     	],
     };

*Note*:

When using the `Cache::Memcached' interface with multiple servers, the
API automatically performs certain operations across all the servers in
the group. For example, getting statistical information through
`Cache::Memcached' returns a hash that contains data on a host by host
basis, as well as generalized statistics for all the servers in the
group.

You can set additional properties on the cache object instance when it
is created by specifying the option as part of the option hash.
Alternatively, you can use a corresponding method on the instance:

   * `servers' or method `set_servers()' -- specifies the list of the
     servers to be used. The servers list should be a reference to an
     array of servers, with each element as the address and port number
     combination (separated by a colon).  You can also specify a local
     connection through a UNIX socket (for example
     `/tmp/sock/memcached'). You can also specify the server with a
     weight (indicating how much more frequently the server should be
     used during hashing) by specifying an array reference with the
     `memcached' server instance and a weight number. Higher numbers
     give higher priority.

   * `compress_threshold' or method `set_compress_threshold()'--
     specifies the threshold when values are compressed. Values larger
     than the specified number are automatically compressed (using
     `zlib') during storage and retrieval.

   * `no_rehash' or method `set_norehash()' -- disables finding a new
     server if the original choice is unavailable.

   * `readonly' or method `set_readonly()'-- disables writes to the
     `memcached' servers.

Once the `Cache::Memcached' object instance has been configured you can
use the `set()' and `get()' methods to store and retrieve information
from the `memcached' servers.  Objects stored in the cache are
automatically serialized and deserialized using the `Storable' module.

The `Cache::Memcached' interface supports the following methods for
storing/retrieving data, and relate to the generic methods as shown in
the table.

`Cache::Memcached' Function          Equivalent to
`get()'                              Generic `get()'
`get_multi(keys)'                    Gets multiple `keys' from memcache
                                     using just one query. Returns a
                                     hash reference of key/value pairs.
`set()'                              Generic `set()'
`add()'                              Generic `add()'
`replace()'                          Generic `replace()'
`delete()'                           Generic `delete()'
`incr()'                             Generic `incr()'
`decr()'                             Generic `decr()'

Below is a complete example for using `memcached' with Perl and the
`Cache::Memcached' module:

     root-shell>!/usr/bin/perl

     use Cache::Memcached;
     use DBI;
     use Data::Dumper;

     # Configure the memcached server

     my $cache = new Cache::Memcached {
         'servers' => [
                        'localhost:11211',
                        ],
         };

     # Get the film name from the command line
     # memcached keys must not contain spaces, so create
     # a key name by replacing spaces with underscores

     my $filmname = shift or die "Must specify the film name\n";
     my $filmkey = $filmname;
     $filmkey =~ s/ /_/;

     # Load the data from the cache

     my $filmdata = $cache->get($filmkey);

     # If the data wasn't in the cache, then we load it from the database

     if (!defined($filmdata))
     {
         $filmdata = load_filmdata($filmname);

         if (defined($filmdata))
         {

     # Set the data into the cache, using the key

     	if ($cache->set($filmkey,$filmdata))
             {
                 print STDERR "Film data loaded from database and cached\n";
             }
             else
             {
                 print STDERR "Couldn't store to cache\n";
     	}
         }
         else
         {
          	die "Couldn't find $filmname\n";
         }
     }
     else
     {
         print STDERR "Film data loaded from Memcached\n";
     }

     sub load_filmdata
     {
         my ($filmname) = @_;

         my $dsn = "DBI:mysql:database=sakila;host=localhost;port=3306";

         $dbh = DBI->connect($dsn, 'sakila','password');

         my ($filmbase) = $dbh->selectrow_hashref(sprintf('select * from film where title = %s',
                                                          $dbh->quote($filmname)));

         if (!defined($filmname))
         {
          	return (undef);
         }

         $filmbase->{stars} =
     	$dbh->selectall_arrayref(sprintf('select concat(first_name," ",last_name) ' .
                                              'from film_actor left join (actor) ' .
                                              'on (film_actor.actor_id = actor.actor_id) ' .
                                              ' where film_id=%s',
                                              $dbh->quote($filmbase->{film_id})));

         return($filmbase);
     }

The example uses the Sakila database, obtaining film data from the
database and writing a composite record of the film and actors to
memcache. When calling it for a film does not exist, you should get
this result:

     shell> memcached-sakila.pl "ROCK INSTINCT"
     Film data loaded from database and cached

When accessing a film that has already been added to the cache:

     shell> memcached-sakila.pl "ROCK INSTINCT"
     Film data loaded from Memcached


File: manual.info,  Node: ha-memcached-interfaces-python,  Next: ha-memcached-interfaces-php,  Prev: ha-memcached-interfaces-perl,  Up: ha-memcached-interfaces

14.5.3.9 Using MySQL and `memcached' with Python
................................................

The Python `memcache' module interfaces to `memcached' servers, and is
written in pure python (i.e. without using one of the C APIs). You can
download and install a copy from Python Memcached
(http://www.tummy.com/Community/software/python-memcached/).

To install, download the package and then run the Python installer:

     python setup.py install
     running install
     running bdist_egg
     running egg_info
     creating python_memcached.egg-info
     ...
     removing 'build/bdist.linux-x86_64/egg' (and everything under it)
     Processing python_memcached-1.43-py2.4.egg
     creating /usr/lib64/python2.4/site-packages/python_memcached-1.43-py2.4.egg
     Extracting python_memcached-1.43-py2.4.egg to /usr/lib64/python2.4/site-packages
     Adding python-memcached 1.43 to easy-install.pth file

     Installed /usr/lib64/python2.4/site-packages/python_memcached-1.43-py2.4.egg
     Processing dependencies for python-memcached==1.43
     Finished processing dependencies for python-memcached==1.43

Once installed, the `memcache' module provides a class-based interface
to your `memcached' servers. Serialization of Python structures is
handled by using the Python `cPickle' or `pickle' modules.

To create a new `memcache' interface, import the `memcache' module and
create a new instance of the `memcache.Client' class:

     import memcache
     memc = memcache.Client(['127.0.0.1:11211'])

The first argument should be an array of strings containing the server
and port number for each `memcached' instance you want to use. You can
enable debugging by setting the optional `debug' parameter to 1.

By default, the hashing mechanism used is `crc32'. This provides a
basic module hashing algorithm for selecting among multiple servers.
You can change the function used by setting the value of
`memcache.serverHashFunction' to the alternate function you want to
use. For example:

     from zlib import adler32
     memcache.serverHashFunction = adler32

Once you have defined the servers to use within the `memcache'
instance, the core functions provide the same functionality as in the
generic interface specification. A summary of the supported functions
is provided in the following table.

Python `memcache' Function           Equivalent to
`get()'                              Generic `get()'
`get_multi(keys)'                    Gets multiple values from the
                                     supplied array of `keys'.  Returns
                                     a hash reference of key/value pairs.
`set()'                              Generic `set()'
`set_multi(dict [, expiry [,         Sets multiple key/value pairs from
key_prefix]])'                       the supplied `dict'.
`add()'                              Generic `add()'
`replace()'                          Generic `replace()'
`prepend(key, value [, expiry])'     Prepends the supplied `value' to
                                     the value of the existing `key'.
`append(key, value [, expiry[)'      Appends the supplied `value' to the
                                     value of the existing `key'.
`delete()'                           Generic `delete()'
`delete_multi(keys [, expiry [,      Deletes all the keys from the hash
key_prefix]] )'                      matching each string in the array
                                     `keys'.
`incr()'                             Generic `incr()'
`decr()'                             Generic `decr()'

*Note*:

Within the Python `memcache' module, all the `*_multi()'functions
support an optional `key_prefix' parameter. If supplied, then the
string is used as a prefix to all key lookups. For example, if you call:

     memc.get_multi(['a','b'], key_prefix='users:')

The function will retrieve the keys `users:a' and `users:b' from the
servers.

An example showing the storage and retrieval of information to a
`memcache' instance, loading the raw data from MySQL, is shown below:

     import sys
     import MySQLdb
     import memcache

     memc = memcache.Client(['127.0.0.1:11211'], debug=1);

     try:
         conn = MySQLdb.connect (host = "localhost",
                                 user = "sakila",
                                 passwd = "password",
                                 db = "sakila")
     except MySQLdb.Error, e:
          print "Error %d: %s" % (e.args[0], e.args[1])
          sys.exit (1)

     popularfilms = memc.get('top5films')

     if not popularfilms:
         cursor = conn.cursor()
         cursor.execute('select film_id,title from film order by rental_rate desc limit 5')
         rows = cursor.fetchall()
         memc.set('top5films',rows,60)
         print "Updated memcached with MySQL data"
     else:
         print "Loaded data from memcached"
         for row in popularfilms:
             print "%s, %s" % (row[0], row[1])

When executed for the first time, the data is loaded from the MySQL
database and stored to the `memcached' server.

     shell> python memc_python.py
     Updated memcached with MySQL data

The data is automatically serialized using `cPickle'/`pickle'. This
means when you load the data back from `memcached', you can use the
object directly. In the example above, the information stored to
`memcached' is in the form of rows from a Python DB cursor. When
accessing the information (within the 60 second expiry time), the data
is loaded from `memcached' and dumped:

     shell> python memc_python.py
     Loaded data from memcached
     2, ACE GOLDFINGER
     7, AIRPLANE SIERRA
     8, AIRPORT POLLOCK
     10, ALADDIN CALENDAR
     13, ALI FOREVER

The serialization and deserialization happens automatically, but be
aware that serialization of Python data may be incompatible with other
interfaces and languages. You can change the serialization module used
during initialization, for example to use JSON, which will be more
easily exchanged.


File: manual.info,  Node: ha-memcached-interfaces-php,  Next: ha-memcached-interfaces-ruby,  Prev: ha-memcached-interfaces-python,  Up: ha-memcached-interfaces

14.5.3.10 Using MySQL and `memcached' with PHP
..............................................

PHP provides support for the Memcache functions through a PECL
extension. To enable the PHP `memcache' extensions, you must build PHP
using the `--enable-memcache' option to `configure' when building from
source.

If you are installing on a RedHat based server, you can install the
`php-pecl-memcache' RPM:

     root-shell> yum --install php-pecl-memcache

On Debian based distributions, use the `php-memcache' package.

You can set global runtime configuration options by specifying the
values in the following table within your `php.ini' file.

Configuration option      Default        Description
`memcache.allow_failover' 1              Specifies whether another
                                         server in the list should be
                                         queried if the first server
                                         selected fails.
`memcache.max_failover_attempts'20             Specifies the number of servers
                                         to try before returning a
                                         failure.
`memcache.chunk_size'     8192           Defines the size of network
                                         chunks used to exchange data
                                         with the `memcached' server.
`memcache.default_port'   11211          Defines the default port to use
                                         when communicating with the
                                         `memcached' servers.
`memcache.hash_strategy'  standard       Specifies which hash strategy
                                         to use. Set to `consistent' to
                                         allow servers to be added or
                                         removed from the pool without
                                         causing the keys to be remapped
                                         to other servers. When set to
                                         `standard', an older (modula)
                                         strategy is used that
                                         potentially uses different
                                         servers for storage.
`memcache.hash_function'  crc32          Specifies which function to use
                                         when mapping keys to servers.
                                         `crc32' uses the standard CRC32
                                         hash.  `fnv' uses the FNV-1a
                                         hashing algorithm.

To create a connection to a `memcached' server, you need to create a
new `Memcache' object and then specifying the connection options. For
example:

     <?php

     $cache = new Memcache;
     $cache->connect('localhost',11121);
     ?>

This opens an immediate connection to the specified server.

To use multiple `memcached' servers, you need to add servers to the
memcache object using `addServer()':

     bool Memcache::addServer ( string $host [, int $port [, bool $persistent
                      [, int $weight [, int $timeout [, int $retry_interval
                      [, bool $status [, callback $failure_callback
                      ]]]]]]] )

The server management mechanism within the `php-memcache' module is a
critical part of the interface as it controls the main interface to the
`memcached' instances and how the different instances are selected
through the hashing mechanism.

To create a simple connection to two `memcached' instances:

     <?php

     $cache = new Memcache;
     $cache->addServer('192.168.0.100',11211);
     $cache->addServer('192.168.0.101',11211);
     ?>

In this scenario the instance connection is not explicitly opened, but
only opened when you try to store or retrieve a value. You can enable
persistent connections to `memcached' instances by setting the
`$persistent' argument to true. This is the default setting, and will
cause the connections to remain open.

To help control the distribution of keys to different instances, you
should use the global `memcache.hash_strategy' setting. This sets the
hashing mechanism used to select. You can also add an additional weight
to each server, which effectively increases the number of times the
instance entry appears in the instance list, therefore increasing the
likelihood of the instance being chosen over other instances. To set
the weight, set the value of the `$weight' argument to more than one.

The functions for setting and retrieving information are identical to
the generic functional interface offered by `memcached', as shown in
this table.

PECL `memcache' Function             Equivalent to
`get()'                              Generic `get()'
`set()'                              Generic `set()'
`add()'                              Generic `add()'
`replace()'                          Generic `replace()'
`delete()'                           Generic `delete()'
`increment()'                        Generic `incr()'
`decrement()'                        Generic `decr()'

A full example of the PECL `memcache' interface is provided below. The
code loads film data from the Sakila database when the user provides a
film name. The data stored into the `memcached' instance is recorded as
a `mysqli' result row, and the API automatically serializes the
information for you.

     <?php

     $memc = new Memcache;
     $memc->addServer('localhost','11211');
     ?>

     <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
     <head>
      <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
      <title>Simple Memcache Lookup</title>
     </head>
     <body>
     <form method="post">
       <p><b>Film</b>: <input type="text" size="20" name="film"></p>
     <input type="submit">
     </form>
     <hr/>

     <?php

       echo "Loading data...\n";

     $value = $memc->get($_REQUEST['film']);

     if ($value)
       {
         printf("<p>Film data for %s loaded from memcache</p>",$value['title']);

         foreach (array_keys($value) as $key)
           {
     	printf("<p><b>%s</b>: %s</p>",$key, $value[$key]);
           }
       }
      else
        {
          $con = new mysqli('localhost','sakila','password','sakila') or
            die ("<h1>Database problem</h1>" . mysqli_connect_error());

          $result = $con->query(sprintf('select * from film where title ="%s"',$_REQUEST['film']));

          $row = $result->fetch_array(MYSQLI_ASSOC);

          $memc->set($row['title'],$row);

          printf("<p>Loaded %s from MySQL</p>",$row['title']);
        }

     ?>

With PHP, the connections to the `memcached' instances are kept open as
long as the PHP and associated Apache instance remain running. When
adding a removing servers from the list in a running instance (for
example, when starting another script that mentions additional
servers), the connections will be shared, but the script will only
select among the instances explicitly configured within the script.

To ensure that changes to the server list within a script do not cause
problems, make sure to use the consistent hashing mechanism.


File: manual.info,  Node: ha-memcached-interfaces-ruby,  Next: ha-memcached-interfaces-java,  Prev: ha-memcached-interfaces-php,  Up: ha-memcached-interfaces

14.5.3.11 Using MySQL and `memcached' with Ruby
...............................................

There are a number of different modules for interfacing to `memcached'
within Ruby. The `Ruby-MemCache' client library provides a native
interface to `memcached' that does not require any external libraries,
such as `libmemcached'. You can obtain the installer package from
`http://www.deveiate.org/projects/RMemCache'.

To install, extract the package and then run `install.rb':

     shell> install.rb

If you have RubyGems, you can install the `Ruby-MemCache' gem:

     shell> gem install Ruby-MemCache
     Bulk updating Gem source index for: http://gems.rubyforge.org
     Install required dependency io-reactor? [Yn]  y
     Successfully installed Ruby-MemCache-0.0.1
     Successfully installed io-reactor-0.05
     Installing ri documentation for io-reactor-0.05...
     Installing RDoc documentation for io-reactor-0.05...

To use a `memcached' instance from within Ruby, create a new instance
of the `MemCache' object.

     require 'memcache'
     memc = MemCache::new '192.168.0.100:11211'

You can add a weight to each server to increase the likelihood of the
server being selected during hashing by appending the weight count to
the server host name/port string:

     require 'memcache'
     memc = MemCache::new '192.168.0.100:11211:3'

To add servers to an existing list, you can append them directly to the
`MemCache' object:

     memc += ["192.168.0.101:11211"]

To set data into the cache, you can just assign a value to a key within
the new cache object, which works just like a standard Ruby hash object:

     memc["key"] = "value"

Or to retrieve the value:

     print memc["key"]

For more explicit actions, you can use the method interface, which
mimics the main `memcached' API functions, as summarized in the
following table.

Ruby `MemCache' Method               Equivalent to
`get()'                              Generic `get()'
`get_hash(keys)'                     Get the values of multiple `keys',
                                     returning the information as a hash
                                     of the keys and their values.
`set()'                              Generic `set()'
`set_many(pairs)'                    Set the values of the keys and
                                     values in the hash `pairs'.
`add()'                              Generic `add()'
`replace()'                          Generic `replace()'
`delete()'                           Generic `delete()'
`incr()'                             Generic `incr()'
`decr()'                             Generic `decr()'


File: manual.info,  Node: ha-memcached-interfaces-java,  Next: ha-memcached-interfaces-mysqludf,  Prev: ha-memcached-interfaces-ruby,  Up: ha-memcached-interfaces

14.5.3.12 Using MySQL and `memcached' with Java
...............................................

The `com.danga.MemCached' class within Java provides a native interface
to `memcached' instances. You can obtain the client from
`http://whalin.com/memcached/'. The Java class uses hashes that are
compatible with `libmemcached', so you can mix and match Java and
`libmemcached' applications accessing the same `memcached' instances.
The serialization between Java and other interfaces will not be
compatible. If this is a problem, use JSON or a similar non-binary
serialization format.

On most systems you can download the package and use the `jar'
directly. On OpenSolaris, use `pkg' to install the `SUNWmemcached-java'
package.

To use the `com.danga.MemCached' interface, you create a
`MemCachedClient' instance and then configure the list of servers by
configuring the `SockIOPool'. Through the pool specification you set up
the server list, weighting, and the connection parameters to optimized
the connections between your client and the `memcached' instances that
you configure.

Generally you can configure the `memcached' interface once within a
single class and then use this interface throughout the rest of your
application.

For example, to create a basic interface, first configure the
`MemCachedClient' and base `SockIOPool' settings:

     public class MyClass {

         protected static MemCachedClient mcc = new MemCachedClient();

         static {

             String[] servers =
                 {
                     "localhost:11211",
                 };

             Integer[] weights = { 1 };

             SockIOPool pool = SockIOPool.getInstance();

             pool.setServers( servers );
             pool.setWeights( weights );

In the above sample, the list of servers is configured by creating an
array of the `memcached' instances that you want to use. You can then
configure individual weights for each server.

The remainder of the properties for the connection are optional, but
you can set the connection numbers (initial connections, minimum
connections, maximum connections, and the idle timeout) by setting the
pool parameters:

     pool.setInitConn( 5 );
     pool.setMinConn( 5 );
     pool.setMaxConn( 250 );
     pool.setMaxIdle( 1000 * 60 * 60 * 6

Once the parameters have been configured, initialize the connection
pool:

     pool.initialize();

The pool, and the connection to your `memcached' instances should now
be ready to use.

To set the hashing algorithm used to select the server used when
storing a given key you can use `pool.setHashingAlg()':

     pool.setHashingAlg( SockIOPool.NEW_COMPAT_HASH );

Valid values ares `NEW_COMPAT_HASH', `OLD_COMPAT_HASH' and
`NATIVE_HASH' are also basic modula hashing algorithms. For a
consistent hashing algorithm, use `CONSISTENT_HASH'. These constants are
equivalent to the corresponding hash settings within `libmemcached'.

Java `com.danga.MemCached' Method    Equivalent to
`get()'                              Generic `get()'
`getMulti(keys)'                     Get the values of multiple `keys',
                                     returning the information as Hash
                                     map using `java.lang.String' for
                                     the keys and `java.lang.Object' for
                                     the corresponding values.
`set()'                              Generic `set()'
`add()'                              Generic `add()'
`replace()'                          Generic `replace()'
`delete()'                           Generic `delete()'
`incr()'                             Generic `incr()'
`decr()'                             Generic `decr()'


File: manual.info,  Node: ha-memcached-interfaces-mysqludf,  Next: ha-memcached-interfaces-protocol,  Prev: ha-memcached-interfaces-java,  Up: ha-memcached-interfaces

14.5.3.13 Using the MySQL `memcached' UDFs
..........................................

The `memcached' MySQL User Defined Functions (UDFs) enable you to set
and retrieve objects from within MySQL 5.0 or greater.

To install the MySQL `memcached' UDFs, download the UDF package from
`http://tangent.org/586/Memcached_Functions_for_MySQL.html'.  You will
need to unpack the package and run `configure' to configure the build
process.  When running `configure', use the `--with-mysql' option and
specify the location of the *Note `mysql_config': mysql-config.
command. Note that you must be running :

     shell> tar zxf memcached_functions_mysql-0.5.tar.gz
     shell> cd memcached_functions_mysql-0.5
     shell> ./configure --with-mysql-config=/usr/local/mysql/bin/mysql_config

Now build and install the functions:

     shell> make
     shell> make install

You may want to copy the MySQL `memcached' UDFs into your MySQL plugins
directory:

     shell> cp /usr/local/lib/libmemcached_functions_mysql* /usr/local/mysql/lib/mysql/plugins/

Once installed, you must initialize the function within MySQL using
`CREATE' and specifying the return value and library. For example, to
add the `memc_get()' function:

     mysql> CREATE FUNCTION memc_get RETURNS STRING SONAME "libmemcached_functions_mysql.so";

You must repeat this process for each function that you want to provide
access to within MySQL. Once you have created the association, the
information will be retained, even over restarts of the MySQL server.
You can simplify the process by using the SQL script provided in the
`memcached' UDFs package:

     shell> mysql <sql/install_functions.sql

Alternatively, if you have Perl installed, then you can use the
supplied Perl script, which will check for the existence of each
function and create the function/library association if it has not
already been defined:

     shell> utils/install.pl --silent

The `--silent' option installs everything automatically. Without this
option, the script will ask whether you want to install each of the
available functions.

The interface remains consistent with the other APIs and interfaces. To
set up a list of servers, use the `memc_servers_set()' function, which
accepts a single string containing and comma-separated list of servers:

     mysql> SELECT memc_servers_set('192.168.0.1:11211,192.168.0.2:11211');

*Note*:

The list of servers used by the `memcached' UDFs is not persistent over
restarts of the MySQL server. If the MySQL server fails, then you must
re-set the list of `memcached' servers.

To set a value, use `memc_set':

     mysql> SELECT memc_set('myid', 'myvalue');

To retrieve a stored value:

     mysql> SELECT memc_get('myid');

The list of functions supported by the UDFs, in relation to the
standard protocol functions, is shown in the following table.

MySQL `memcached' UDF Function       Equivalent to
`memc_get()'                         Generic `get()'
`memc_get_by_key(master_key, key,    Like the generic `get()', but uses
value)'                              the supplied master key to select
                                     the server to use.
`memc_set()'                         Generic `set()'
`memc_set_by_key(master_key, key,    Like the generic `set()', but uses
value)'                              the supplied master key to select
                                     the server to use.
`memc_add()'                         Generic `add()'
`memc_add_by_key(master_key, key,    Like the generic `add()', but uses
value)'                              the supplied master key to select
                                     the server to use.
`memc_replace()'                     Generic `replace()'
`memc_replace_by_key(master_key,     Like the generic `replace()', but
key, value)'                         uses the supplied master key to
                                     select the server to use.
`memc_prepend(key, value)'           Prepend the specified `value' to
                                     the current value of the specified
                                     `key'.
`memc_prepend_by_key(master_key,     Prepend the specified `value' to
key, value)'                         the current value of the specified
                                     `key', but uses the supplied master
                                     key to select the server to use.
`memc_append(key, value)'            Append the specified `value' to the
                                     current value of the specified
                                     `key'.
`memc_append_by_key(master_key,      Append the specified `value' to the
key, value)'                         current value of the specified
                                     `key', but uses the supplied master
                                     key to select the server to use.
`memc_delete()'                      Generic `delete()'
`memc_delete_by_key(master_key,      Like the generic `delete()', but
key, value)'                         uses the supplied master key to
                                     select the server to use.
`memc_increment()'                   Generic `incr()'
`memc_decrement()'                   Generic `decr()'

The respective `*_by_key()' functions are useful when you want to store
a specific value into a specific `memcached' server, possibly based on a
differently calculated or constructed key.

The `memcached' UDFs include some additional functions:

   * `memc_server_count()'

     Returns a count of the number of servers in the list of registered
     servers.

   * `memc_servers_set_behavior(behavior_type, value)',
     `memc_set_behavior(behavior_type, value)'

     Set behaviors for the list of servers. These behaviors are
     identical to those provided by the `libmemcached' library. For more
     information on `libmemcached' behaviors, see *Note
     ha-memcached-interfaces-libmemcached::.

     You can use the behavior name as the `behavior_type':

          mysql> SELECT memc_servers_behavior_set("MEMCACHED_BEHAVIOR_KETAMA",1);

   * `memc_servers_behavior_get(behavior_type)',
     `memc_get_behavior(behavior_type, value)'

     Returns the value for a given behavior.

   * `memc_list_behaviors()'

     Returns a list of the known behaviors.

   * `memc_list_hash_types()'

     Returns a list of the supported key-hashing algorithms.

   * `memc_list_distribution_types()'

     Returns a list of the supported distribution types to be used when
     selecting a server to use when storing a particular key.

   * `memc_libmemcached_version()'

     Returns the version of the `libmemcached' library.

   * `memc_stats()'

     Returns the general statistics information from the server.


File: manual.info,  Node: ha-memcached-interfaces-protocol,  Prev: ha-memcached-interfaces-mysqludf,  Up: ha-memcached-interfaces

14.5.3.14 `memcached' Protocol
..............................

* Menu:

* ha-memcached-interfaces-protocol-tcp::  Using the TCP text protocol

Communicating with a `memcached' server can be achieved through either
the TCP or UDP protocols. When using the TCP protocol you can use a
simple text based interface for the exchange of information.


File: manual.info,  Node: ha-memcached-interfaces-protocol-tcp,  Prev: ha-memcached-interfaces-protocol,  Up: ha-memcached-interfaces-protocol

14.5.3.15 Using the TCP text protocol
.....................................

When communicating with `memcached' you can connect to the server using
the port configured for the server. You can open a connection with the
server without requiring authorization or login. As soon as you have
connected, you can start to send commands to the server. When you have
finished, you can terminate the connection without sending any specific
disconnection command. Clients are encouraged to keep their connections
open to decrease latency and improve performance.

Data is sent to the `memcached' server in two forms:

   * Text lines, which are used to send commands to the server, and
     receive responses from the server.

   * Unstructured data, which is used to receive or send the value
     information for a given key. Data is returned to the client in
     exactly the format it was provided.

Both text lines (commands and responses) and unstructured data are
always terminated with the string `\r\n'.  Because the data being
stored may contain this sequence, the length of the data (returned by
the client before the unstructured data is transmitted should be used
to determine the end of the data.

Commands to the server are structured according to their operation:

   * *Storage commands*: `set', `add', `replace', `append', `prepend',
     `cas'

     Storage commands to the server take the form:

          command key [flags] [exptime] length [noreply]

     Or when using compare and swap (cas):

          cas key [flags] [exptime] length [casunique] [noreply]

     Where:

        * `command' -- the command name.

             * `set' -- Store value against key

             * `add' -- Store this value against key if the key does
               not already exist

             * `replace' -- Store this value against key if the key
               already exists

             * `append' -- Append the supplied value to the end of the
               value for the specified key. The `flags' and `exptime'
               arguments should not be used.

             * `prepend' -- Append value currently in the cache to the
               end of the supplied value for the specified key. The
               `flags' and `exptime' arguments should not be used.

             * `cas' -- Set the specified key to the supplied value,
               only if the supplied `casunique' matches. This is
               effectively the equivalent of change the information if
               nobody has updated it since I last fetched it.

        * `key' -- the key. All data is stored using a the specific
          key. The key cannot contain control characters or whitespace,
          and can be up to 250 characters in size.

        * `flags' -- the flags for the operation (as an integer). Flags
          in `memcached' are transparent. The `memcached' server
          ignores the contents of the flags. They can be used by the
          client to indicate any type of information. In `memcached'
          1.2.0 and lower the value is a 16-bit integer value. In
          `memcached' 1.2.1 and higher the value is a 32-bit integer.

        * `exptime' -- the expiry time, or zero for no expiry.

        * `length' -- the length of the supplied value block in bytes,
          excluding the terminating `\r\n' characters.

        * `casunique' -- is a unique 64-bit value of an existing entry.
          This will be used to compare against the existing value. You
          should use the value returned by the `gets' command when
          issuing `cas' updates.

        * `noreply' -- tells the server not to reply to the command.

     For example, to store the value `abcdef' into the key `xyzkey',
     you would use:

          set xyzkey 0 0 6\r\nabcdef\r\n

     The return value from the server will be one line, specifying the
     status or error information. For more information, see *Note
     ha-memcached-interfaces-protocol-responses::.

   * *Retrieval commands*: `get', `gets'

     Retrieval commands take the form:

          get key1 [key2 .... keyn]
          gets key1 [key2 ... keyn]

     You can supply multiple keys to the commands, with each requested
     key separated by whitespace.

     The server will respond with an information line of the form:

          VALUE key flags bytes [casunique]

     Where:

        * `key' -- the key name.

        * `flags' -- the value of the flag integer supplied to the
          `memcached' server when the value was stored.

        * `bytes' -- the size (excluding the terminating `\r\n'
          character sequence) of the stored value.

        * `casunique' -- the unique 64-bit integer that identifies the
          item.

     The information line will immediately be followed by the value
     data block. For example:

          get xyzkey\r\n
          VALUE xyzkey 0 6\r\n
          abcdef\r\n

     If you have requested multiple keys, an information line and data
     block will be returned for each key found. If a requested key does
     not exist in the cache, no information is returned.

   * *Delete commands*: `delete'

     Deletion commands take the form:

          delete key [time] [noreply]

     Where:

        * `key' -- the key name.

        * `time' -- the time in seconds (or a specific Unix time) for
          which the client wishes the server to refuse `add' or
          `replace' commands on this key. All `add', `replace', `get',
          and `gets' commands will fail during this period.  `set'
          operations will succeed. After this period, the key will be
          deleted permanently and all commands will be accepted.

          If not supplied, the value is assumed to be zero (delete
          immediately).

        * `noreply' -- tells the server not to reply to the command.

     Responses to the command will either be `DELETED' to indicate that
     the key was successfully removed, or `NOT_FOUND' to indicate that
     the specified key could not be found.

   * *Increment/Decrement*: `incr', `decr'

     The increment and decrement commands change the value of a key
     within the server without performing a separate get/set sequence.
     The operations assume that the currently stored value is a 64-bit
     integer. If the stored value is not a 64-bit integer, then the
     value is assumed to be zero before the increment or decrement
     operation is applied.

     Increment and decrement commands take the form:

          incr key value [noreply]
          decr key value [noreply]

     Where:

        * `key' -- the key name.

        * `value' -- an integer to be used as the increment or
          decrement value.

        * `noreply' -- tells the server not to reply to the command.

     The response will be:

        * `NOT_FOUND' -- the specified key could not be located.

        * `value' -- the new value of the specified key.

     Values are assumed to be unsigned. For `decr' operations the value
     will never be decremented below 0. For `incr' operations, the
     value will be wrap around the 64-bit maximum.

   * *Statistics commands*: `stats'

     The `stats' command provides detailed statistical information
     about the current status of the `memcached' instance and the data
     it is storing.

     Statistics commands take the form:

          STAT [name] [value]

     Where:

        * `name' -- is the optional name of the statistics to return.
          If not specified, the general statistics are returned.

        * `value' -- a specific value to be used when performing
          certain statistics operations.

     The return value is a list of statistics data, formatted as
     follows:

          STAT name value

     The statistics are terminated with a single line, `END'.

     For more information, see *Note ha-memcached-stats::.

For reference, a list of the different commands supported and their
formats is provided below.

*`memcached' Command Reference*

Command            Command Formats
`set'              `set key flags exptime length', `set key flags
                   exptime length noreply'
`add'              `add key flags exptime length', `add key flags
                   exptime length noreply'
`replace'          `replace key flags exptime length', `replace key
                   flags exptime length noreply'
`append'           `append key length', `append key length noreply'
`prepend'          `prepend key length', `prepend key length noreply'
`cas'              `cas key flags exptime length casunique', `cas key
                   flags exptime length casunique noreply'
`get'              `get key1 [key2 ... keyn]'
`gets'             `'
`delete'           `delete key', `delete key noreply', `delete key
                   expiry', `delete key expory noreply'
`incr'             `incr key', `incr key noreply', `incr key value',
                   `incr key value noreply'
`decr'             `decr key', `decr key noreply', `decr key value',
                   `decr key value noreply'
`stat'             `stat', `stat name', `stat name value'

When sending a command to the server, the response from the server will
be one of the settings in the following table. All response values from
the server are terminated by `\r\n':

*`memcached' Protocol Responses*

String             Description
`STORED'           Value has successfully been stored.
`NOT_STORED'       The value was not stored, but not because of an
                   error. For commands where you are adding a or
                   updating a value if it exists (such as `add' and
                   `replace'), or where the item has already been set to
                   be deleted.
`EXISTS'           When using a `cas' command, the item you are trying to
                   store already exists and has been modified since you
                   last checked it.
`NOT_FOUND'        The item you are trying to store, update or delete
                   does not exist or has already been deleted.
`ERROR'            You submitted a non-existent command name.
`CLIENT_ERROR      There was an error in the input line, the detail is
errorstring'       contained in `errorstring'.
`SERVER_ERROR      There was an error in the server that prevents it
errorstring'       from returning the information. In extreme
                   conditions, the server may disconnect the client
                   after this error occurs.
`VALUE keys flags  The requested key has been found, and the stored
length'            `key', `flags' and data block will be returned, of
                   the specified `length'.
`DELETED'          The requested key was deleted from the server.
`STAT name value'  A line of statistics data.
`END'              The end of the statistics data.


File: manual.info,  Node: ha-memcached-stats,  Next: ha-memcached-faq,  Prev: ha-memcached-interfaces,  Up: ha-memcached

14.5.4 Getting `memcached' Statistics
-------------------------------------

* Menu:

* ha-memcached-stats-general::   `memcached' General Statistics
* ha-memcached-stats-slabs::     `memcached' Slabs Statistics
* ha-memcached-stats-items::     `memcached' Item Statistics
* ha-memcached-stats-sizes::     `memcached' Size Statistics

The `memcached' system has a built in statistics system that collects
information about the data being stored into the cache, cache hit
ratios, and detailed information on the memory usage and distribution
of information through the slab allocation used to store individual
items. Statistics are provided at both a basic level that provide the
core statistics, and more specific statistics for specific areas of the
`memcached' server.

This information can prove be very useful to ensure that you are
getting the correct level of cache and memory usage, and that your slab
allocation and configuration properties are set at an optimal level.

The stats interface is available through the standard `memcached'
protocol, so the reports can be accessed by using `telnet' to connect
to the `memcached'. Alternatively, most of the language API interfaces
provide a function for obtaining the statistics from the server.

For example, to get the basic stats using `telnet':

     shell> telnet localhost 11211
     Trying ::1...
     Connected to localhost.
     Escape character is '^]'.
     stats
     STAT pid 23599
     STAT uptime 675
     STAT time 1211439587
     STAT version 1.2.5
     STAT pointer_size 32
     STAT rusage_user 1.404992
     STAT rusage_system 4.694685
     STAT curr_items 32
     STAT total_items 56361
     STAT bytes 2642
     STAT curr_connections 53
     STAT total_connections 438
     STAT connection_structures 55
     STAT cmd_get 113482
     STAT cmd_set 80519
     STAT get_hits 78926
     STAT get_misses 34556
     STAT evictions 0
     STAT bytes_read 6379783
     STAT bytes_written 4860179
     STAT limit_maxbytes 67108864
     STAT threads 1
     END

When using Perl and the `Cache::Memcached' module, the `stats()'
function returns information about all the servers currently configured
in the connection object, and total statistics for all the `memcached'
servers as a whole.

For example, the following Perl script will obtain the stats and dump
the hash reference that is returned:

     use Cache::Memcached;
     use Data::Dumper;

     my $memc = new Cache::Memcached;
     $memc->set_servers(\@ARGV);

     print Dumper($memc->stats());

When executed on the same `memcached' as used in the `Telnet' example
above we get a hash reference with the host by host and total
statistics:

     $VAR1 = {
         'hosts' => {
                'localhost:11211' => {
                           'misc' => {
                                 'bytes' => '2421',
                                 'curr_connections' => '3',
                                 'connection_structures' => '56',
                                 'pointer_size' => '32',
                                 'time' => '1211440166',
                                 'total_items' => '410956',
                                 'cmd_set' => '588167',
                                 'bytes_written' => '35715151',
                                 'evictions' => '0',
                                 'curr_items' => '31',
                                 'pid' => '23599',
                                 'limit_maxbytes' => '67108864',
                                 'uptime' => '1254',
                                 'rusage_user' => '9.857805',
                                 'cmd_get' => '838451',
                                 'rusage_system' => '34.096988',
                                 'version' => '1.2.5',
                                 'get_hits' => '581511',
                                 'bytes_read' => '46665716',
                                 'threads' => '1',
                                 'total_connections' => '3104',
                                 'get_misses' => '256940'
                               },
                           'sizes' => {
                                  '128' => '16',
                                  '64' => '15'
                                }
                         }
              },
         'self' => {},
         'total' => {
                'cmd_get' => 838451,
                'bytes' => 2421,
                'get_hits' => 581511,
                'connection_structures' => 56,
                'bytes_read' => 46665716,
                'total_items' => 410956,
                'total_connections' => 3104,
                'cmd_set' => 588167,
                'bytes_written' => 35715151,
                'curr_items' => 31,
                'get_misses' => 256940
              }
             };

The statistics are divided up into a number of distinct sections, and
then can be requested by adding the type to the `stats' command. Each
statistics output is covered in more detail in the following sections.

   * General statistics, see *Note ha-memcached-stats-general::.

   * Slab statistics (`slabs'), see *Note ha-memcached-stats-slabs::.

   * Item statistics (`items'), see *Note ha-memcached-stats-items::.

   * Size statistics (`sizes'), see *Note ha-memcached-stats-sizes::.


File: manual.info,  Node: ha-memcached-stats-general,  Next: ha-memcached-stats-slabs,  Prev: ha-memcached-stats,  Up: ha-memcached-stats

14.5.4.1 `memcached' General Statistics
.......................................

The output of the general statistics provides an overview of the
performance and use of the `memcached' instance. The statistics
returned by the command and their meaning is shown in the following
table.

The following terms are used to define the value type for each
statistics value:

   * `32u' -- 32-bit unsigned integer

   * `64u' -- 64-bit unsigned integer

   * `32u32u' -- Two 32-bit unsigned integers separated by a colon

   * `String' -- Character string

Statistic      Description 
pid            32u         Process id of the `memcached' instance.
uptime         32u         Uptime (in seconds) for this `memcached'
                           instance.
time           32u         Current time (as epoch).
version        string      Version string of this instance.
pointer_size   string      Size of pointers for this host specified in
                           bits (32 or 64).
rusage_user    32u:32u     Total user time for this instance
                           (seconds:microseconds).
rusage_system  32u:32u     Total system time for this instance
                           (seconds:microseconds).
curr_items     32u         Current number of items stored by this
                           instance.
total_items    32u         Total number of items stored during the life
                           of this instance.
bytes          64u         Current number of bytes used by this server to
                           store items.
curr_connections32u         Current number of open connections.
total_connections32u         Total number of connections opened since the
                           server started running.
connection_structures32u         Number of connection structures allocated by
                           the server.
cmd_get        64u         Total number of retrieval requests (`get'
                           operations).
cmd_set        64u         Total number of storage requests (`set'
                           operations).
get_hits       64u         Number of keys that have been requested and
                           found present.
get_misses     64u         Number of items that have been requested and
                           not found.
evictions      64u         Number of valid items removed from cache to
                           free memory for new items.
bytes_read     64u         Total number of bytes read by this server from
                           network.
bytes_written  64u         Total number of bytes sent by this server to
                           network.
limit_maxbytes 32u         Number of bytes this server is allowed to use
                           for storage.
threads        32u         Number of worker threads requested.

The most useful statistics from those given here are the number of
cache hits, misses, and evictions.

A large number of `get_misses' may just be an indication that the cache
is still being populated with information. The number should, over
time, decrease in comparison to the number of cache `get_hits'.  If,
however, you have a large number of cache misses compared to cache hits
after an extended period of execution, it may be an indication that the
size of the cache is too small and you either need to increase the
total memory size, or increase the number of the `memcached' instances
to improve the hit ratio.

A large number of `evictions' from the cache, particularly in
comparison to the number of items stored is a sign that your cache is
too small to hold the amount of information that you regularly want to
keep cached. Instead of items being retained in the cache, items are
being evicted to make way for new items keeping the turnover of items
in the cache high, reducing the efficiency of the cache.


File: manual.info,  Node: ha-memcached-stats-slabs,  Next: ha-memcached-stats-items,  Prev: ha-memcached-stats-general,  Up: ha-memcached-stats

14.5.4.2 `memcached' Slabs Statistics
.....................................

To get the `slabs' statistics, use the `stats slabs' command, or the
API equivalent.

The slab statistics provide you with information about the slabs that
have created and allocated for storing information within the cache.
You get information both on each individual slab-class and total
statistics for the whole slab.

     STAT 1:chunk_size 104
     STAT 1:chunks_per_page 10082
     STAT 1:total_pages 1
     STAT 1:total_chunks 10082
     STAT 1:used_chunks 10081
     STAT 1:free_chunks 1
     STAT 1:free_chunks_end 10079
     STAT 9:chunk_size 696
     STAT 9:chunks_per_page 1506
     STAT 9:total_pages 63
     STAT 9:total_chunks 94878
     STAT 9:used_chunks 94878
     STAT 9:free_chunks 0
     STAT 9:free_chunks_end 0
     STAT active_slabs 2
     STAT total_malloced 67083616
     END

Individual stats for each slab class are prefixed with the slab ID. A
unique ID is given to each allocated slab from the smallest size up to
the largest. The prefix number indicates the slab class number in
relation to the calculated chunk from the specified growth factor.
Hence in the example, 1 is the first chunk size and 9 is the 9th chunk
allocated size.

The different parameters returned for each chunk size and the totals
are shown in the following table.

Statistic          Description
chunk_size         Space allocated to each chunk within this slab class.
chunks_per_page    Number of chunks within a single page for this slab
                   class.
total_pages        Number of pages allocated to this slab class.
total_chunks       Number of chunks allocated to the slab class.
used_chunks        Number of chunks allocated to an item..
free_chunks        Number of chunks not yet allocated to items.
free_chunks_end    Number of free chunks at the end of the last
                   allocated page.
active_slabs       Total number of slab classes allocated.
total_malloced     Total amount of memory allocated to slab pages.

The key values in the slab statistics are the `chunk_size', and the
corresponding `total_chunks' and `used_chunks' parameters. These given
an indication of the size usage of the chunks within the system.
Remember that one key/value pair will be placed into a chunk of a
suitable size.

From these stats you can get an idea of your size and chunk allocation
and distribution. If you are storing many items with a number of
largely different sizes, then you may want to adjust the chunk size
growth factor to increase in larger steps to prevent chunk and memory
wastage. A good indication of a bad growth factor is a high number of
different slab classes, but with relatively few chunks actually in use
within each slab.  Increasing the growth factor will create fewer slab
classes and therefore make better use of the allocated pages.


File: manual.info,  Node: ha-memcached-stats-items,  Next: ha-memcached-stats-sizes,  Prev: ha-memcached-stats-slabs,  Up: ha-memcached-stats

14.5.4.3 `memcached' Item Statistics
....................................

To get the `items' statistics, use the `stats items' command, or the
API equivalent.

The `items' statistics give information about the individual items
allocated within a given slab class.

     STAT items:2:number 1
     STAT items:2:age 452
     STAT items:2:evicted 0
     STAT items:2:outofmemory 0
     STAT items:27:number 1
     STAT items:27:age 452
     STAT items:27:evicted 0
     STAT items:27:outofmemory 0

The prefix number against each statistics relates to the corresponding
chunk size, as returned by the `stats slabs' statistics. The result is
a display of the number of items stored within each chunk within each
slab size, and specific statistics about their age, eviction counts, and
out of memory counts. A summary of the statistics is given in the
following table.

Statistic          Description
number             The number of items currently stored in this slab
                   class.
age                The age of the oldest item within the slab class, in
                   seconds.
evicted            The number of items evicted to make way for new
                   entries.
outofmemory        The number of items for this slab class that have
                   triggered an out of memory error (only value when the
                   `-M' command line option is in effect).

Item level statistics can be used to determine how many items are
stored within a given slab and their freshness and recycle rate. You
can use this to help identify whether there are certain slab classes
that are triggering a much larger number of evictions that others.


File: manual.info,  Node: ha-memcached-stats-sizes,  Prev: ha-memcached-stats-items,  Up: ha-memcached-stats

14.5.4.4 `memcached' Size Statistics
....................................

To get size statistics, use the `stats sizes' command, or the API
equivalent.

The size statistics provide information about the sizes and number of
items of each size within the cache. The information is returned as two
columns, the first column is the size of the item (rounded up to the
nearest 32 byte boundary), and the second column is the count of the
number of items of that size within the cache:

     96 35
     128 38
     160 807
     192 804
     224 410
     256 222
     288 83
     320 39
     352 53
     384 33
     416 64
     448 51
     480 30
     512 54
     544 39
     576 10065

*Caution*:

Running this statistic will lock up your cache as each item is read
from the cache and its size calculated. On a large cache, this may take
some time and prevent any set or get operations until the process
completes.

The item size statistics are useful only to determine the sizes of the
objects you are storing. Since the actual memory allocation is relevant
only in terms of the chunk size and page size, the information will
only be useful during a careful debugging or diagnostic session.


File: manual.info,  Node: ha-memcached-faq,  Prev: ha-memcached-stats,  Up: ha-memcached

14.5.5 `memcached' FAQ
----------------------

*Questions*
   * 14.5.5.1: How does an event such as a crash of one of the
     `memcached' servers handled by the `memcached' client?

   * 14.5.5.2: Are there any, or are there any plans to introduce, a
     framework to hide the interaction of memcached from the
     application, i.e., within hibernate?

   * 14.5.5.3: What's a recommended hardware config for a memcached
     server?  Linux or Windows?

   * 14.5.5.4: How expensive is it to establish a memcache connection?
     Should those connections be pooled?

   * 14.5.5.5: How will the data will be handled when the `memcached'
     server is down?

   * 14.5.5.6: Can memcached be run on a Windows environment?

   * 14.5.5.7: What is the max size of an object you can store in
     memcache and is that configurable?

   * 14.5.5.8: Is it true `memcached' will be much more effective with
     db-read-intensive applications than with db-write-intensive
     applications?

   * 14.5.5.9: What are best practices for testing an implementation,
     to ensure that it is an improvement over the MySQL query cache,
     and to measure the impact of `memcached' configuration changes?
     And would you recommend keeping the configuration very simple to
     start?

   * 14.5.5.10: Can MySQL actually trigger/store the changed data to
     memcached?

   * 14.5.5.11: So the responsibility lies with the application to
     populate and get records from the database as opposed to being a
     transparent cache layer for the db?

   * 14.5.5.12: `memcached' is fast - is there any overhead in not
     using persistent connections? If persistent is always recommended,
     what are the downsides (e.g. locking up?)

   * 14.5.5.13: Is compression available?

   * 14.5.5.14: File socket support for `memcached' from the localhost
     use to the local memcached server?

   * 14.5.5.15: What are the advantages of using UDFs when the get/sets
     are manageable from within the client code rather than the db?

   * 14.5.5.16: Is `memcached' typically a better solution for
     improving speed than MySQL Cluster and\or MySQL Proxy?

   * 14.5.5.17: What speed trade offs is there between `memcached' vs
     MySQL Query Cache? Where you check `memcached', and get data from
     MySQL and put it in `memcached' or just make a query and results
     are put into MySQL Query Cache.

   * 14.5.5.18: Does the `-L' flag automatically sense how much memory
     is being used by other memcached?

   * 14.5.5.19: Is the data inside of `memcached' secure?

   * 14.5.5.20: Can we implement different types of `memcached' as
     different nodes in the same server - so can there be deterministic
     and non deterministic in the same server?

   * 14.5.5.21: How easy is it to introduce `memcached' to an existing
     enterprise application instead of inclusion at project design?

   * 14.5.5.22: Can `memcached' work with `ASPX'?

   * 14.5.5.23: If I have an object larger then a MB, do I have to
     manually split it or can I configure `memcached' to handle larger
     objects?

   * 14.5.5.24: How does `memcached' compare to nCache?

   * 14.5.5.25: Doing a direct telnet to the memcached port, is that
     just for that one machine, or does it magically apply across all
     nodes?

   * 14.5.5.26: Is memcached more effective for video and audio as
     opposed to textual read/writes

   * 14.5.5.27: We are caching XML by serialising using saveXML(),
     because PHP cannot serialise DOM objects; Some of the XML is
     variable and is modified per-request. Do you recommend caching
     then using XPath, or is it better to rebuild the DOM from separate
     node-groups?

   * 14.5.5.28: Do the memcache UDFs work under 5.1?

   * 14.5.5.29: How are auto-increment columns in the MySQL database
     coordinated across multiple instances of memcached?

   * 14.5.5.30: If you log a complex class (with methods that do
     calculation etc) will the get from Memcache re-create the class on
     the way out?

*Questions and Answers* *14.5.5.1: ** How does an event such as a crash
of one of the `memcached' servers handled by the `memcached' client?  *

There is no automatic handling of this. If your client fails to get a
response from a server then it should fall back to loading the data
from the MySQL database.

The client APIs all provide the ability to add and remove `memcached'
instances on the fly. If within your application you notice that
`memcached' server is no longer responding, your can remove the server
from the list of servers, and keys will automatically be redistributed
to another `memcached' server in the list. If retaining the cache
content on all your servers is important, make sure you use an API that
supports a consistent hashing algorithm. For more information, see
*Note ha-memcached-using-hashtypes::.

*14.5.5.2: ** Are there any, or are there any plans to introduce, a
framework to hide the interaction of memcached from the application,
i.e., within hibernate?  *

There are lots of projects working with `memcached'. There is a Google
Code implementation of Hibernate and `memcached' working together. See
`http://code.google.com/p/hibernate-memcached/'.

*14.5.5.3: ** What's a recommended hardware config for a memcached
server?  Linux or Windows?  *

`memcached' is only available on Unix/Linux, so using a Windows machine
is not an option. Outside of this, `memcached' has a very low
processing overhead.  All that is required is spare physical RAM
capacity. The point is not that you should necessarily deploy a
dedicated `memcached' server. If you have web, application, or database
servers that have spare RAM capacity, then use them with `memcached'.

If you want to build and deploy a dedicated `memcached' servers, then
you use a relatively low-power CPU, lots of RAM and one or more Gigabit
Ethernet interfaces.

*14.5.5.4: ** How expensive is it to establish a memcache connection?
Should those connections be pooled?  *

Opening the connection is relatively inexpensive, because there is no
security, authentication or other handshake taking place before you can
start sending requests and getting results. Most APIs support a
persistent connection to a `memcached' instance to reduce the latency.
Connection pooling would depend on the API you are using, but if you
are communicating directly over TCP/IP, then connection pooling would
provide some small performance benefit.

*14.5.5.5: ** How will the data will be handled when the `memcached'
server is down?  *

The behavior is entirely application dependent. Most applications will
fall back to loading the data from the database (just as if they were
updating the `memcached') information. If you are using multiple
`memcached' servers, you may also want to remove a server from the list
to prevent the missing server affecting performance. This is because
the client will still attempt to communicate the `memcached' that
corresponds to the key you are trying to load.

*14.5.5.6: ** Can memcached be run on a Windows environment?  *

No. Currently `memcached' is available only on the Unix/Linux platform.
There is an unofficial port available, see
`http://www.codeplex.com/memcachedproviders'.

*14.5.5.7: ** What is the max size of an object you can store in
memcache and is that configurable?  *

The default maximum object size is 1MB. If you want to increase this
size, you have to re-compile `memcached'.  You can modify the value of
the `POWER_BLOCK' within the `slabs.c' file within the source.

*14.5.5.8: ** Is it true `memcached' will be much more effective with
db-read-intensive applications than with db-write-intensive
applications?  *

Yes. `memcached' plays no role in database writes, it is a method of
caching data already read from the database in RAM.

*14.5.5.9: ** What are best practices for testing an implementation, to
ensure that it is an improvement over the MySQL query cache, and to
measure the impact of `memcached' configuration changes? And would you
recommend keeping the configuration very simple to start?  *

The best way to test the performance is to start up a `memcached'
instance. First, modify your application so that it stores the data
just before the data is about to be used or displayed into
`memcached'.Since the APIs handle the serialization of the data, it
should just be a one line modification to your code. Then, modify the
start of the process that would normally load that information from
MySQL with the code that requests the data from `memcached'.  If the
data cannot be loaded from `memcached', default to the MySQL process.

All of the changes required will probably amount to just a few lines of
code. To get the best benefit, make sure you cache entire objects (for
example, all the components of a web page, blog post, discussion
thread, etc.), rather than using `memcached' as a simple cache of
individuals rows of MySQL tables. You should see performance benefits
almost immediately.

Keeping the configuration very simple at the start, or even over the
long term, is very easy with `memcached'.  Once you have the basic
structure up and running, the only addition you may want to make is to
add more servers into the list of servers used by your clients. You
don't need to manage the `memcached' servers, and there is no complex
configuration, just add more servers to the list and let the client API
and the `memcached' servers make the decisions.

*14.5.5.10: ** Can MySQL actually trigger/store the changed data to
memcached?  *

Yes. You can use the MySQL UDFs for `memcached' and either write
statements that directly set the values in the `memcached' server, or
use triggers or stored procedures to do it for you. For more
information, see *Note ha-memcached-interfaces-mysqludf::

*14.5.5.11: ** So the responsibility lies with the application to
populate and get records from the database as opposed to being a
transparent cache layer for the db?  *

Yes. You load the data from the database and write it into the cache
provided by `memcached'. Using `memcached' as a simple database row
cache, however, is probably inefficient. The best way to use
`memcached' is to load all of the information from the database
relating to a particular object, and then cache the entire object. For
example, in a blogging environment, you might load the blog, associated
comments, categories and so on, and then cache all of the information
relating to that blog post. The reading of the data from the database
will require multiple SQL statements and probably multiple rows of data
to complete, which is time consuming. Loading the entire blog post and
the associated information from `memcached' is just one operation and
doesn't involve using the disk or parsing the SQL statement.

*14.5.5.12: ** `memcached' is fast - is there any overhead in not using
persistent connections? If persistent is always recommended, what are
the downsides (e.g. locking up?)  *

If you don't use persistent connections when communicating with
`memcached' then there will be a small increase in the latency of
opening the connection each time. The effect is comparable to use
non-persistent connections with MySQL.

In general, the chance of locking or other issues with persistent
connections is minimal, because there is very little locking within
`memcached'. If there is a problem then eventually your request will
timeout and return no result so your application will need to load from
MySQL again.

*14.5.5.13: ** Is compression available?  *

Yes. Most of the client APIs support some sort of compression, and some
even allow you to specify the threshold at which a value is deemed
appropriate for compression during storage.

*14.5.5.14: ** File socket support for `memcached' from the localhost
use to the local memcached server?  *

You can use the `-s' option to `memcached' to specify the location of a
file socket. This automatically disables network support.

*14.5.5.15: ** What are the advantages of using UDFs when the get/sets
are manageable from within the client code rather than the db?  *

Sometimes you want to be able to be able to update the information
within `memcached' based on a generic database activity, rather than
relying on your client code. For example, you may want to update status
or counter information in `memcached' through the use of a trigger or
stored procedure. For some situations and applications the existing use
of a stored procedure for some operations means that updating the value
in `memcached' from the database is easier than separately loading and
communicating that data to the client just so the client can talk to
`memcached.'

In other situations, when you are using a number of different clients
and different APIs, you don't want to have to write (and maintain) the
code required to update `memcached' in all the environments. Instead,
you do this from within the database and the client never gets involved.

*14.5.5.16: ** Is `memcached' typically a better solution for improving
speed than MySQL Cluster and\or MySQL Proxy?  *

Both MySQL Cluster and MySQL Proxy still require access to the
underlying database to retrieve the information. This implies both a
parsing overhead for the statement and, often, disk based access to
retrieve the data you have selected.

The advantage of `memcached' is that you can store entire objects or
groups of information that may require multiple SQL statements to
obtain. Restoring the result of 20 SQL statements formatted into a
structure that your application can use directly without requiring any
additional processing is always going to be faster than building that
structure by loading the rows from a database.

*14.5.5.17: ** What speed trade offs is there between `memcached' vs
MySQL Query Cache? Where you check `memcached', and get data from MySQL
and put it in `memcached' or just make a query and results are put into
MySQL Query Cache.  *

In general, the time difference between getting data from the MySQL
Query Cache and getting the exact same data from `memcached' is very
small.

However, the benefit of `memcached' is that you can store any
information, including the formatted and processed results of many
queries into a single `memcached' key. Even if all the queries that you
executed could be retrieved from the Query Cache without having to go
to disk, you would still be running multiple queries (with network and
other overhead) compared to just one for the `memcached' equivalent. If
your application uses objects, or does any kind of processing on the
information, with `memcached' you can store the post-processed version,
so the data you load is immediately available to be used. With data
loaded from the Query Cache, you would still have to do that processing.

In addition to these considerations, keep in mind that keeping data in
the MySQL Query Cache is difficult as you have no control over the
queries that are stored. This means that a slightly unusual query can
temporarily clear a frequently used (and normally cached) query,
reducing the effectiveness of your Query Cache. With `memcached' you
can specify which objects are stored, when they are stored, and when
they should be deleted giving you much more control over the
information stored in the cache.

*14.5.5.18: ** Does the `-L' flag automatically sense how much memory
is being used by other memcached?  *

No. There is no communication or sharing of information between
`memcached' instances.

*14.5.5.19: ** Is the data inside of `memcached' secure?  *

No, there is no security required to access or update the information
within a `memcached' instance, which means that anybody with access to
the machine has the ability to read, view and potentially update the
information. If you want to keep the data secure, you can encrypt and
decrypt the information before storing it. If you want to restrict the
users capable of connecting to the server, your only choice is to
either disable network access, or use IPTables or similar to restrict
access to the `memcached' ports to a select set of hosts.

*14.5.5.20: ** Can we implement different types of `memcached' as
different nodes in the same server - so can there be deterministic and
non deterministic in the same server?  *

Yes. You can run multiple instances of `memcached' on a single server,
and in your client configuration you choose the list of servers you
want to use.

*14.5.5.21: ** How easy is it to introduce `memcached' to an existing
enterprise application instead of inclusion at project design?  *

In general, it is very easy. In many languages and environments the
changes to the application will be just a few lines, first to attempt
to read from the cache when loading data and then fall back to the old
method, and to update the cache with information once the data has been
read.

`memcached' is designed to be deployed very easily, and you shouldn't
require significant architectural changes to your application to use
`memcached'.

*14.5.5.22: ** Can `memcached' work with `ASPX'?  *

There are ports and interfaces for many languages and environments.
ASPX relies on an underlying language such as C# or VisualBasic, and if
you are using ASP.NET then there is a C# `memcached' library. For more
information, see . (https://sourceforge.net/projects/memcacheddotnet/)

*14.5.5.23: ** If I have an object larger then a MB, do I have to
manually split it or can I configure `memcached' to handle larger
objects?  *

You would have to manually split it.  `memcached' is very simple, you
give it a key and some data, it tries to cache it in RAM. If you try to
store more than the default maximum size, the value is just truncated
for speed reasons.

*14.5.5.24: ** How does `memcached' compare to nCache?  *

The main benefit of `memcached' is that is very easy to deploy and
works with a wide range of languages and environments, including .NET,
Java, Perl, Python, PHP, even MySQL. `memcached' is also very
lightweight in terms of systems and requirements, and you can easily
add as many or as few `memcached' servers as you need without changing
the individual configuration.  `memcached' does require additional
modifications to the application to take advantage of functionality
such as multiple `memcached' servers.

*14.5.5.25: ** Doing a direct telnet to the memcached port, is that
just for that one machine, or does it magically apply across all nodes?
*

Just one. There is no communication between different instances of
`memcached', even if each instance is running on the same machine.

*14.5.5.26: ** Is memcached more effective for video and audio as
opposed to textual read/writes *

`memcached' doesn't care what information you are storing. To
`memcached', any value you store is just a stream of data. Remember,
though, that the maximum size of an object you can store in `memcached'
without modifying the source code is 1MB, so it's usability with audio
and video content is probably significantly reduced. Also remember that
`memcached' is a solution for caching information for reading. It
shouldn't be used for writes, except when updating the information in
the cache.

*14.5.5.27: ** We are caching XML by serialising using saveXML(),
because PHP cannot serialise DOM objects; Some of the XML is variable
and is modified per-request. Do you recommend caching then using XPath,
or is it better to rebuild the DOM from separate node-groups?  *

You would need to test your application using the different methods to
determine this information. You may find that the default serialization
within PHP may allow you to store DOM objects directly into the cache.

*14.5.5.28: ** Do the memcache UDFs work under 5.1?  *

Yes.

*14.5.5.29: ** How are auto-increment columns in the MySQL database
coordinated across multiple instances of memcached?  *

They aren't. There is no relationship between MySQL and `memcached'
unless your application (or, if you are using the MySQL UDFs for
`memcached', your database definition) creates one.

If you are storing information based on an auto-increment key into
multiple instances of `memcached' then the information will only be
stored on one of the `memcached' instances anyway. The client uses the
key value to determine which `memcached' instance to store the
information, it doesn't store the same information across all the
instances, as that would be a waste of cache memory.

*14.5.5.30: ** If you log a complex class (with methods that do
calculation etc) will the get from Memcache re-create the class on the
way out?  *

In general, yes. If the serialization method within the API/language
that you are using supports it, then methods and other information will
be stored and retrieved.


File: manual.info,  Node: mysql-proxy,  Prev: ha-memcached,  Up: ha-overview

14.6 MySQL Proxy
================

* Menu:

* mysql-proxy-platforms::        MySQL Proxy Supported Platforms
* mysql-proxy-install::          Installing MySQL Proxy
* mysql-proxy-cmdline::          MySQL Proxy Command-Line Options
* mysql-proxy-scripting::        MySQL Proxy Scripting
* mysql-proxy-using::            Using MySQL Proxy
* mysql-proxy-faq::              MySQL Proxy FAQ

The MySQL Proxy is an application that communicates over the network
using the MySQL Network Protocol and provides communication between one
or more MySQL servers and one or more MySQL clients. In the most basic
configuration, MySQL Proxy simply passes on queries from the client to
the MySQL Server and returns the responses from the MySQL Server to the
client.

Because MySQL Proxy uses the MySQL network protocol, any MySQL
compatible client (include the command line client, any clients using
the MySQL client libraries, and any connector that supports the MySQL
network protocol) can connect to the proxy without modification.

In addition to the basic pass-through configuration, the MySQL Proxy is
also capable of monitoring and altering the communication between the
client and the server. This interception of the queries enables you to
add profiling, and the interception of the exchanges is scriptable
using the Lua scripting language.

By intercepting the queries from the client, the proxy can insert
additional queries into the list of queries sent to the server, and
remove the additional results when they are returned by the server.
Using this functionality you can add informational statements to each
query, for example to monitor their execution time or progress, and
separately log the results, while still returning the results from the
original query to the client.

The proxy allows you to perform additional monitoring, filtering or
manipulation on queries without you having to make any modifications to
the client and without the client even being aware that it is
communicating with anything but a genuine MySQL server.

*Warning*:

MySQL Proxy is currently an Alpha release and should not be used within
production environments.

*Important*:

MySQL Proxy is compatible with MySQL 5.0.x or later. Testing has not
been performed with Version 4.1. Please provide feedback on your
experiences via the MySQL Proxy Forum
(http://forums.mysql.com/list.php?146).


File: manual.info,  Node: mysql-proxy-platforms,  Next: mysql-proxy-install,  Prev: mysql-proxy,  Up: mysql-proxy

14.6.1 MySQL Proxy Supported Platforms
--------------------------------------

MySQL Proxy is currently available as a pre-compiled binary for the
following platforms:

   * Linux (including RedHat, Fedora, Debian, SuSE) and derivatives.

   * Mac OS X

   * FreeBSD

   * IBM AIX

   * Sun Solaris

Other Unix/Linux platforms not listed should be compatible by using the
source package and building MySQL Proxy locally.

System requirements for the MySQL Proxy application are the same as the
main MySQL server. Currently MySQL Proxy is compatible only with MySQL
5.0.1 and later. MySQL Proxy is provided as a standalone, statically
linked binary. You do not need to have MySQL or Lua installed.


File: manual.info,  Node: mysql-proxy-install,  Next: mysql-proxy-cmdline,  Prev: mysql-proxy-platforms,  Up: mysql-proxy

14.6.2 Installing MySQL Proxy
-----------------------------

* Menu:

* mysql-proxy-install-binary::   Installing MySQL Proxy from a binary distribution
* mysql-proxy-install-source::   Installing MySQL Proxy from a source distribution
* mysql-proxy-install-svn::      Installing MySQL Proxy from the Subversion repository

You have three choices for installing MySQL Proxy:

   * Pre-compiled binaries are available for a number of different
     platforms. See *Note mysql-proxy-install-binary::.

   * You can install from the source code if you want to build on an
     environment not supported by the binary distributions. See *Note
     mysql-proxy-install-source::.

   * The latest version of the MySQL proxy source code is available
     through a development repository is the best way to stay up to
     date with the latest fixes and revisions. See *Note
     mysql-proxy-install-svn::.


File: manual.info,  Node: mysql-proxy-install-binary,  Next: mysql-proxy-install-source,  Prev: mysql-proxy-install,  Up: mysql-proxy-install

14.6.2.1 Installing MySQL Proxy from a binary distribution
..........................................................

If you download the binary packages then you need only to extract the
package and then copy the *Note `mysql-proxy': mysql-proxy. file to
your desired location.  For example:

     shell> tar zxf MYSQL-PROXY-0.5.0.TAR.GZ
     shell> cp ./mysql-proxy-0.5.0/sbin/mysql-proxy /usr/local/sbin


File: manual.info,  Node: mysql-proxy-install-source,  Next: mysql-proxy-install-svn,  Prev: mysql-proxy-install-binary,  Up: mysql-proxy-install

14.6.2.2 Installing MySQL Proxy from a source distribution
..........................................................

If you have downloaded the source package then you will need to compile
the MySQL Proxy before using it. To build you will need to have the
following installed:

   * libevent 1.x or higher (1.3b or later is preferred)

   * lua 5.1.x or higher

   * glib2 2.6.0 or higher

   * pkg-config

   * MySQL 5.0.x or higher developer files

*Note*:

On some operating systems you may need to manually build the required
components to get the latest version. If you are having trouble
compiling MySQL Proxy then consider using one of the binary
distributions.

Once these components are installed, you need to configure and then
build:

     shell> tar zxf MYSQL-PROXY-0.5.0.TAR.GZ
     shell> cd mysql-proxy-0.5.0
     shell> ./configure
     shell> make

If you want to test the build, then use the `check' target to `make':

     shell> make check

The tests try to connect to `localhost' using the `root' user. If you
need to provide a password, set the `MYSQL_PASSWORD' environment
variable:

     shell> MYSQL_PASSWORD=root_pwd make check

You can install using the `install' target:

     shell> make install

By default *Note `mysql-proxy': mysql-proxy. is installed into
`/usr/local/sbin/mysql-proxy'. The Lua example scripts are copied into
`/usr/local/share'.


File: manual.info,  Node: mysql-proxy-install-svn,  Prev: mysql-proxy-install-source,  Up: mysql-proxy-install

14.6.2.3 Installing MySQL Proxy from the Subversion repository
..............................................................

The MySQL Proxy source is available through a public Subversion
repository and is the quickest way to get hold of the latest releases
and fixes.

To build from the Subversion repository, you need the following
components already installed:

   * Subversion 1.3.0 or higher

   * `libtool' 1.5 or higher

   * `autoconf' 2.56 or higher

   * `automake' 1.9 or higher

   * `libevent' 1.x or higher (1.3b or later is preferred)

   * `lua' 5.1.x or higher

   * `glib2' 2.4.0 or higher

   * `pkg-config'

   * `MySQL' 5.0.x or higher developer files

To checkout a local copy of the Subversion repository, use `svn':

     shell> svn co http://svn.MySQL.com/svnpublic/mysql-proxy/ mysql-proxy

The above command will download a complete version of the Subversion
repository for `mysql-proxy'. The main source files are located within
the `trunk' subdirectory. The configuration scripts need to be
generated before you can configure and build `mysql-proxy'. The
`autogen.sh' script will generate the configuration scripts for you:

     shell> sh ./autogen.sh

The script creates the standard `configure' script, which you can then
use to configure and build with `make':

     shell> ./configure
     shell> make
     shell> make install

If you want to create a standalone source distribution, identical to
the source distribution available for download:

     shell> make distcheck

The above will create the file `mysql-proxy-0.5.0.tar.gz' within the
current directory.


File: manual.info,  Node: mysql-proxy-cmdline,  Next: mysql-proxy-scripting,  Prev: mysql-proxy-install,  Up: mysql-proxy

14.6.3 MySQL Proxy Command-Line Options
---------------------------------------

To start *Note `mysql-proxy': mysql-proxy. you can just run the command
directly. However, for most situations you will want to specify at the
very least the address/host name and port number of the backend MySQL
server to which the MySQL Proxy should pass on queries.

You can get a list of the supported command-line options using the
`--help-all' command-line option. The majority of these options set up
the environment, either in terms of the address/port number that *Note
`mysql-proxy': mysql-proxy. should listen on for connections, or the
onward connection to a MySQL server. A full description of the options
is shown below:

   * `--help-all' -- show all help options.

   * `--help-admin ' -- show options for the admin-module.

   * `--help-proxy' -- Show options for the proxy-module.

   * `--admin-address=host:port' -- specify the host name (or IP
     address) and port for the administration port. The default is
     `localhost:4041'.

   * `--proxy-address=host:port' -- the listening host name (or IP
     address) and port of the proxy server. The default is
     `localhost:4040'.

   * `--proxy-read-only-backend-address=host:port' -- the listening
     host name (or IP address) and port of the proxy server for
     read-only connections. The default is for this information not to
     be set.

   * `--proxy-backend-addresses=host:port' -- the host name (or IP
     address) and port of the MySQL server to connect to. You can
     specify multiple backend servers by supplying multiple options.
     Clients are connected to each backend server in round-robin
     fashion. For example, if you specify two servers A and B, the
     first client connection will go to server A; the second client
     connection to server B and the third client connection to server A.

   * `--proxy-skip-profiling ' -- disables profiling of queries
     (tracking time statistics). The default is for tracking to be
     enabled.

   * `--proxy-fix-bug-25371 ' -- gets round an issue when connecting to
     a MySQL server later than 5.1.12 when using a MySQL client library
     of any earlier version.

   * `--proxy-lua-script=file ' -- specify the Lua script file to be
     loaded. Note that the script file is not physically loaded and
     parsed until a connection is made.  Also note that the specified
     Lua script is reloaded for each connection; if the content of the
     Lua script changes while *Note `mysql-proxy': mysql-proxy. is
     running then the updated content will automatically be used when a
     new connection is made.

   * `--daemon' -- starts the proxy in daemon mode.

   * `--pid-file=file' -- sets the name of the file to be used to store
     the process ID.

   * `--version' -- show the version number.

The most common usage is as a simple proxy service (i.e. without
addition scripting). For basic proxy operation you must specify at
least one `proxy-backend-addresses' option to specify the MySQL server
to connect to by default:

     shell> mysql-proxy
     --proxy-backend-addresses=MySQL.example.com:3306

The default proxy port is `4040', so you can connect to your MySQL
server through the proxy by specifying the host name and port details:

     shell> mysql --host=localhost --port=4040

If your server requires authentication information then this will be
passed through natively without alteration by *Note `mysql-proxy':
mysql-proxy, so you must also specify the authentication information if
required:

     shell> mysql --host=localhost --port=4040 \
        --user=username --password=password

You can also connect to a read-only port (which filters out *Note
`UPDATE': update. and *Note `INSERT': insert. queries) by connecting to
the read-only port. By default the host name is the default, and the
port is `4042', but you can alter the host/port information by using the
`--proxy-read-only-address' command-line option.

For more detailed information on how to use these command line options,
and *Note `mysql-proxy': mysql-proxy. in general in combination with
Lua scripts, see *Note mysql-proxy-using::.


File: manual.info,  Node: mysql-proxy-scripting,  Next: mysql-proxy-using,  Prev: mysql-proxy-cmdline,  Up: mysql-proxy

14.6.4 MySQL Proxy Scripting
----------------------------

* Menu:

* mysql-proxy-scripting-injection::  Proxy Scripting Sequence During Query Injection
* mysql-proxy-scripting-structures::  Internal Structures
* mysql-proxy-scripting-connect-server::  Capturing a connection with `connect_server()'
* mysql-proxy-scripting-read-handshake::  Examining the handshake with `read_handshake()'
* mysql-proxy-scripting-read-auth::  Examining the authentication credentials with `read_auth()'
* mysql-proxy-scripting-read-auth-result::  Accessing authentication information with `read_auth_result()'
* mysql-proxy-scripting-read-query::  Manipulating Queries with `read_query()'
* mysql-proxy-scripting-read-query-result::  Manipulating Results with `read_query_result()'

You can control how MySQL Proxy manipulates and works with the queries
and results that are passed on to the MySQL server through the use of
the embedded Lua scripting language. You can find out more about the
Lua programming language from the Lua Website (http://www.lua.org).

The primary interaction between MySQL Proxy and the server is provided
by defining one or more functions through an Lua script.  A number of
functions are supported, according to different events and operations
in the communication sequence between a client and one or more backend
MySQL servers:

   * `connect_server()' -- this function is called each time a
     connection is made to MySQL Proxy from a client. You can use this
     function during load-balancing to intercept the original
     connection and decide which server the client should ultimately be
     attached to. If you do not define a special solution, then a
     simple round-robin style distribution is used by default.

   * `read_handshake()' -- this function is called when the initial
     handshake information is returned by the server. You can capture
     the handshake information returned and provide additional checks
     before the authorization exchange takes place.

   * `read_auth()' -- this function is called when the authorization
     packet (user name, password, default database) are submitted by
     the client to the server for authentication.

   * `read_auth_result()' -- this function is called when the server
     returns an authorization packet to the client indicating whether
     the authorization succeeded.

   * `read_query()' -- this function is called each time a query is
     sent by the client to the server.  You can use this to edit and
     manipulate the original query, including adding new queries before
     and after the original statement. You can also use this function
     to return information directly to the client, bypassing the server,
     which can be useful to filter unwanted queries or queries that
     exceed known limits.

   * `read_query_result()' -- this function is called each time a
     result is returned from the server, providing you have manually
     injected queries into the query queue. If you have not explicitly
     inject queries within the `read_query()' function then this
     function is not triggered. You can use this to edit the result
     set, or to remove or filter the result sets generated from
     additional queries you injected into the queue when using
     `read_query()'.

The table below describes the direction of flow of information at the
point when the function is triggered.

Function               Supplied Information   Direction
`connect_server()'     None                   Client to Server
`read_handshake()'     Handshake packet       Server to Client
`read_auth()'          Authorization packet   Client to Server
`read_auth_result()'   Authorization response Server to Client
`read_query()'         Query                  Client to Server
`read_query_result()'  Query result           Server to Client

By default, all functions return a result that indicates that the data
should be passed on to the client or server (depending on the direction
of the information being transferred). This return value can be
overridden by explicitly returning a constant indicating that a
particular response should be sent. For example, it is possible to
construct result set information by hand within `read_query()' and to
return the resultset directly to the client without ever sending the
original query to the server.

In addition to these functions, a number of built-in structures provide
control over how MySQL Proxy forwards on queries and returns the
results by providing a simplified interface to elements such as the
list of queries and the groups of result sets that are returned.


File: manual.info,  Node: mysql-proxy-scripting-injection,  Next: mysql-proxy-scripting-structures,  Prev: mysql-proxy-scripting,  Up: mysql-proxy-scripting

14.6.4.1 Proxy Scripting Sequence During Query Injection
........................................................

The figure below gives an example of how the proxy might be used when
injecting queries into the query queue. Because the proxy sits between
the client and MySQL server, what the proxy sends to the server, and
the information that the proxy ultimately returns to the client do not
have to match or correlate. Once the client has connected to the proxy,
the following sequence occurs for each individual query sent by the
client.

MySQL Proxy architecture

  1. The client submits one query to the proxy, the `read_query()'
     function within the proxy is triggered. The function adds the
     query to the query queue.

  2. Once manipulation by `read_query()' has completed, the queries are
     submitted, sequentially, to the MySQL server.

  3. The MySQL server returns the results from each query, one result
     set for each query submitted. The `read_query_result()' function is
     triggered for each result set, and each invocation can decide
     which result set to return to the client

For example, you can queue additional queries into the global query
queue to be processed by the server. This can be used to add
statistical information by adding queries before and after the original
query, changing the original query:

     SELECT * FROM City;

Into a sequence of queries:

     SELECT NOW();
     SELECT * FROM City;
     SELECT NOW();

You can also modify the original statement, for example to add *Note
`EXPLAIN': explain. to each statement executed to get information on
how the statement was processed, again altering our original SQL
statement into a number of statements:

     SELECT * FROM City;
     EXPLAIN SELECT * FROM City;

In both of these examples, the client would have received more result
sets than expected. Regardless of how you manipulate the incoming query
and the returned result, the number of queries returned by the proxy
must match the number of original queries sent by the client.

You could adjust the client to handle the multiple result sets sent by
the proxy, but in most cases you will want the existence of the proxy
to remain transparent. To ensure that the number of queries and result
sets match, you can use the MySQL Proxy `read_query_result()' to
extract the additional result set information and return only the
result set the client originally requested back to the client. You can
achieve this by giving each query that you add to the query queue a
unique ID, and then filter out queries that do not match the original
query ID when processing them with `read_query_result()'.


File: manual.info,  Node: mysql-proxy-scripting-structures,  Next: mysql-proxy-scripting-connect-server,  Prev: mysql-proxy-scripting-injection,  Up: mysql-proxy-scripting

14.6.4.2 Internal Structures
............................

There are a number of internal structures within the scripting element
of MySQL Proxy. The primary structure is `proxy' and this provides an
interface to the many common structures used throughout the script,
such as connection lists and configured backend servers. Other
structures, such as the incoming packet from the client and result sets
are only available within the context of one of the scriptable
functions.

Attribute              Description
`connection'           A structure containing the active client
                       connections. For a list of attributes, see
                       `proxy.connection'.
`servers'              A structure containing the list of configured
                       backend servers. For a list of attributes, see
                       `proxy.backends'.
`queries'              A structure containing the queue of queries that
                       will be sent to the server during a single client
                       query. For a list of attributes, see
                       `proxy.queries'.
`PROXY_VERSION'        The version number of MySQL Proxy, encoded in
                       hex. You can use this to check that the version
                       number supports a particular option from within
                       the Lua script. Note that the value is encoded as
                       a hex value, so to check the version is at least
                       0.5.1 you compare against `0x00501'.

* `proxy.connection' *

The `proxy.connection' object is read only, and provides information
about the current connection.

Attribute              Description
`thread_id'            The thread ID of the connection.
`backend_ndx'          The ID of the server used for this connection.
                       This is an ID valid against the list of
                       configured servers available through the
                       `proxy.backends' object.

* `proxy.backends' *

The `proxy.backends' table is partially writable and contains an array
of all the configured backend servers and the server metadata (IP
address, status, etc.). You can determine the array index of the
current connection using `proxy.connection["backend_ndx"]' which is the
index into this table of the backend server being used by the active
connection.

The attributes for each entry within the `proxy.backends' table are
shown in this table.

Attribute              Description
`address'              The host name/port combination used for this
                       connection
`connected_clients'    The number of clients currently connected.
`state'                The status of the backend server. See *Note
                       mysql-proxy-scripting-structures-backend-states::.

* `proxy.queries' *

The `proxy.queries' object is a queue representing the list of queries
to be sent to the server. The queue is not populated automatically, but
if you do not explicitly populate the queue then queries are passed on
to the backend server verbatim. Also, if you do not populate the query
queue by hand, then the `read_query_result()' function is not triggered.

The following methods are supported for populating the `proxy.queries'
object.

Function               Description
`append(id,packet)'    Appends a query to the end of the query queue.
                       The `id' is an integer identifier that you can
                       use to recognize the query results when they are
                       returned by the server.  The packet should be a
                       properly formatted query packet.
`prepend(id,packet)'   Prepends a query to the query queue. The `id' is
                       an identifier that you can use to recognize the
                       query results when they are returned by the
                       server. The packet should be a properly formatted
                       query packet.
`reset()'              Empties the query queue.
`len()'                Returns the number of query packets in the queue.

For example, you could append a query packet to the `proxy.queries'
queue by using the `append()':

     proxy.queries:append(1,packet)

*`proxy.response'*

The `proxy.response' structure is used when you want to return your own
MySQL response, instead of forwarding a packet that you have received a
backend server. The structure holds the response type information, an
optional error message, and the result set (rows/columns) that you want
to return.

Attribute              Description
`type'                 The type of the response. The type must be either
                       `MYSQLD_PACKET_OK' or `MYSQLD_PACKET_ERR'. If the
                       `MYSQLD_PACKET_ERR', then you should set the
                       value of the `mysql.response.errmsg' with a
                       suitable error message.
`errmsg'               A string containing the error message that will
                       be returned to the client.
`resultset'            A structure containing the result set information
                       (columns and rows), identical to what would be
                       returned when returning a results from a *Note
                       `SELECT': select.  query.

When using `proxy.response' you either set `proxy.response.type' to
`proxy.MYSQLD_PACKET_OK' and then build `resultset' to contain the
results that you want to return, or set `proxy.response.type' to
`proxy.MYSQLD_PACKET_ERR' and set the `proxy.response.errmsg' to a
string with the error message. To send the completed resultset or error
message, you should return the `proxy.PROXY_SEND_RESULT' to trigger the
return of the packet information.

An example of this can be seen in the `tutorial-resultset.lua' script
within the MySQL Proxy package:

     if string.lower(command) == "show" and string.lower(option) == "querycounter" then
             ---
             -- proxy.PROXY_SEND_RESULT requires
             --
             -- proxy.response.type to be either
             -- * proxy.MYSQLD_PACKET_OK or
             -- * proxy.MYSQLD_PACKET_ERR
             --
             -- for proxy.MYSQLD_PACKET_OK you need a resultset
             -- * fields
             -- * rows
             --
             -- for proxy.MYSQLD_PACKET_ERR
             -- * errmsg
             proxy.response.type = proxy.MYSQLD_PACKET_OK
             proxy.response.resultset = {
                     fields = {
                             { type = proxy.MYSQL_TYPE_LONG, name = "global_query_counter", },
                             { type = proxy.MYSQL_TYPE_LONG, name = "query_counter", },
                     },
                     rows = {
                             { proxy.global.query_counter, query_counter }
                     }
             }

             -- we have our result, send it back
             return proxy.PROXY_SEND_RESULT
     elseif string.lower(command) == "show" and string.lower(option) == "myerror" then
             proxy.response.type = proxy.MYSQLD_PACKET_ERR
             proxy.response.errmsg = "my first error"

             return proxy.PROXY_SEND_RESULT

*`proxy.response.resultset'*

The `proxy.response.resultset' structure should be populated with the
rows and columns of data that you want to return. The structure
contains the information about the entire result set, with the
individual elements of the data shown in the table below.

Attribute              Description
`fields'               The definition of the columns being returned.
                       This should be a dictionary structure with the
                       `type' specifying the MySQL data type, and the
                       `name' specifying the column name.  Columns
                       should be listed in the order of the column data
                       that will be returned.
`flags'                A number of flags related to the resultset. Valid
                       flags include `auto_commit' (whether an automatic
                       commit was triggered), `no_good_index_used' (the
                       query executed without using an appropriate
                       index), and `no_index_used' (the query executed
                       without using any index).
`rows'                 The actual row data. The information should be
                       returned as an array of arrays. Each inner array
                       should contain the column data, with the outer
                       array making up the entire result set.
`warning_count'        The number of warnings for this result set.
`affected_rows'        The number of rows affected by the original
                       statement.
`insert_id'            The last insert ID for an auto-incremented column
                       in a table.
`query_status'         The status of the query operation. You can use the
                       `MYSQLD_PACKET_OK' or `MYSQLD_PACKET_ERR'
                       constants to populate this parameter.

For an example of the population of this table, see *Note
mysql-proxy-scripting-structures-response::.

*Proxy Return State Constants*

The following constants are used internally by the proxy to specify the
response to send to the client or server. All constants are exposed as
values within the main `proxy' table.

Constant               Description
`PROXY_SEND_QUERY'     Causes the proxy to send the current contents of
                       the queries queue to the server.
`PROXY_SEND_RESULT'    Causes the proxy to send a result set back to the
                       client.
`PROXY_IGNORE_RESULT'  Causes the proxy to drop the result set (nothing
                       is returned to the client).

As constants, these entities are available without qualification in the
Lua scripts. For example, at the end of the `read_query_result()' you
might return `PROXY_IGNORE_RESULT:'

     return proxy.PROXY_IGNORE_RESULT

*Packet State Constants*

The following states describe the status of a network packet.  These
items are entries within the main `proxy' table.

Constant               Description
`MYSQLD_PACKET_OK'     The packet is OK.
`MYSQLD_PACKET_ERR'    The packet contains error information.
`MYSQLD_PACKET_RAW'    The packet contains raw data.

*Backend State/Type Constants*

The following constants are used either to define the status of the
backend server (the MySQL server to which the proxy is connected) or
the type of backend server. These items are entries within the main
`proxy' table.

Constant               Description
`BACKEND_STATE_UNKNOWN'The current status is unknown.
`BACKEND_STATE_UP'     The backend is known to be up (available).
`BACKEND_STATE_DOWN'   The backend is known to be down (unavailable).
`BACKEND_TYPE_UNKNOWN' Backend type is unknown.
`BACKEND_TYPE_RW'      Backend is available for read/write.
`BACKEND_TYPE_RO'      Backend is available only for read-only use.

*Server Command Constants*

The following values are used in the packets exchanged between the
client and server to identify the information in the rest of the
packet. These items are entries within the main `proxy' table. The
packet type is defined as the first character in the sent packet. For
example, when intercepting packets from the client to edit or monitor a
query you would check that the first byte of the packet was of type
`proxy.COM_QUERY'.

Constant               Description
`COM_SLEEP'            Sleep
`COM_QUIT'             Quit
`COM_INIT_DB'          Initialize database
`COM_QUERY'            Query
`COM_FIELD_LIST'       Field List
`COM_CREATE_DB'        Create database
`COM_DROP_DB'          Drop database
`COM_REFRESH'          Refresh
`COM_SHUTDOWN'         Shutdown
`COM_STATISTICS'       Statistics
`COM_PROCESS_INFO'     Process List
`COM_CONNECT'          Connect
`COM_PROCESS_KILL'     Kill
`COM_DEBUG'            Debug
`COM_PING'             Ping
`COM_TIME'             Time
`COM_DELAYED_INSERT'   Delayed insert
`COM_CHANGE_USER'      Change user
`COM_BINLOG_DUMP'      Binlog dump
`COM_TABLE_DUMP'       Table dump
`COM_CONNECT_OUT'      Connect out
`COM_REGISTER_SLAVE'   Register slave
`COM_STMT_PREPARE'     Prepare server-side statement
`COM_STMT_EXECUTE'     Execute server-side statement
`COM_STMT_SEND_LONG_DATA'Long data
`COM_STMT_CLOSE'       Close server-side statement
`COM_STMT_RESET'       Reset statement
`COM_SET_OPTION'       Set option
`COM_STMT_FETCH'       Fetch statement
`COM_DAEMON'           Daemon (MySQL 5.1 only)
`COM_ERROR'            Error

*MySQL Type Constants*

These constants are used to identify the field types in the query
result data returned to clients from the result of a query. These items
are entries within the main `proxy' table.

Constant               Field Type
`MYSQL_TYPE_DECIMAL'   Decimal
`MYSQL_TYPE_NEWDECIMAL'Decimal (MySQL 5.0 or later)
`MYSQL_TYPE_TINY'      Tiny
`MYSQL_TYPE_SHORT'     Short
`MYSQL_TYPE_LONG'      Long
`MYSQL_TYPE_FLOAT'     Float
`MYSQL_TYPE_DOUBLE'    Double
`MYSQL_TYPE_NULL'      Null
`MYSQL_TYPE_TIMESTAMP' Timestamp
`MYSQL_TYPE_LONGLONG'  Long long
`MYSQL_TYPE_INT24'     Integer
`MYSQL_TYPE_DATE'      Date
`MYSQL_TYPE_TIME'      Time
`MYSQL_TYPE_DATETIME'  Datetime
`MYSQL_TYPE_YEAR'      Year
`MYSQL_TYPE_NEWDATE'   Date (MySQL 5.0 or later)
`MYSQL_TYPE_ENUM'      Enumeration
`MYSQL_TYPE_SET'       Set
`MYSQL_TYPE_TINY_BLOB' Tiny Blob
`MYSQL_TYPE_MEDIUM_BLOB'Medium Blob
`MYSQL_TYPE_LONG_BLOB' Long Blob
`MYSQL_TYPE_BLOB'      Blob
`MYSQL_TYPE_VAR_STRING'Varstring
`MYSQL_TYPE_STRING'    String
`MYSQL_TYPE_TINY'      Tiny (compatible with `MYSQL_TYPE_CHAR)'
`MYSQL_TYPE_ENUM'      Enumeration (compatible with
                       `MYSQL_TYPE_INTERVAL')
`MYSQL_TYPE_GEOMETRY'  Geometry
`MYSQL_TYPE_BIT'       Bit


File: manual.info,  Node: mysql-proxy-scripting-connect-server,  Next: mysql-proxy-scripting-read-handshake,  Prev: mysql-proxy-scripting-structures,  Up: mysql-proxy-scripting

14.6.4.3 Capturing a connection with `connect_server()'
.......................................................

When the proxy accepts a connection from a MySQL client, the
`connect_server()' function is called.

There are no arguments to the function, but you can use and if
necessary manipulate the information in the `proxy.connection' table,
which is unique to each client session.

For example, if you have multiple backend servers then you can set the
server to be used by that connection by setting the value of
`proxy.connection.backend_ndx' to a valid server number. The code below
will choose between two servers based on whether the current time in
minutes is odd or even:

     function connect_server()
             print("--> a client really wants to talk to a server")
             if (tonumber(os.date("%M")) % 2 == 0) then
                     proxy.connection.backend_ndx = 2
                     print("Choosing backend 2")
             else
                     proxy.connection.backend_ndx = 1
                     print("Choosing backend 1")
             end
             print("Using " .. proxy.backends[proxy.connection.backend_ndx].address)
     end

In this example the IP address/port combination is also displayed by
accessing the information from the internal `proxy.backends' table.


File: manual.info,  Node: mysql-proxy-scripting-read-handshake,  Next: mysql-proxy-scripting-read-auth,  Prev: mysql-proxy-scripting-connect-server,  Up: mysql-proxy-scripting

14.6.4.4 Examining the handshake with `read_handshake()'
........................................................

Handshake information is sent by the server to the client after the
initial connection (through `connect_server()') has been made. The
handshake information contains details about the MySQL version, the ID
of the thread that will handle the connection information, and the IP
address of the client and server. This information is exposed through a
Lua table as the only argument to the function.

   * `mysqld_version' -- the version of the MySQL server.

   * `thread_id' -- the thread ID.

   * `scramble' -- the password scramble buffer.

   * `server_addr' -- the IP address of the server.

   * `client_addr' -- the IP address of the client.

For example, you can print out the handshake data and refuse clients by
IP address with the following function:

     function read_handshake( auth )
             print("<-- let's send him some information about us")
             print("    mysqld-version: " .. auth.mysqld_version)
             print("    thread-id     : " .. auth.thread_id)
             print("    scramble-buf  : " .. string.format("%q", auth.scramble))
             print("    server-addr   : " .. auth.server_addr)
             print("    client-addr   : " .. auth.client_addr)

             if not auth.client_addr:match("^127.0.0.1:") then
                     proxy.response.type = proxy.MYSQLD_PACKET_ERR
                     proxy.response.errmsg = "only local connects are allowed"

                     print("we don't like this client");

                     return proxy.PROXY_SEND_RESULT
             end
     end

Note that you have to return an error packet to the client by using
`proxy.PROXY_SEND_RESULT'.


File: manual.info,  Node: mysql-proxy-scripting-read-auth,  Next: mysql-proxy-scripting-read-auth-result,  Prev: mysql-proxy-scripting-read-handshake,  Up: mysql-proxy-scripting

14.6.4.5 Examining the authentication credentials with `read_auth()'
....................................................................

The `read_auth()' function is triggered when an authentication
handshake is initiated by the client. In the execution sequence,
`read_auth()' occurs immediately after `read_handshake()', so the
server selection has already been made, but the connection and
authorization information has not yet been provided to the backend
server.

The function accepts a single argument, an Lua table containing the
authorization information for the handshake process. The entries in the
table are:

   * `username' -- the user login for connecting to the server.

   * `password' -- the password, encrypted, to be used when connecting.

   * `default_db' -- the default database to be used once the
     connection has been made.

For example, you can print the user name and password supplied during
authorization using:

     function read_auth( auth )
             print("    username      : " .. auth.username)
             print("    password      : " .. string.format("%q", auth.password))
     end

You can interrupt the authentication process within this function and
return an error packet back to the client by constructing a new packet
and returning `proxy.PROXY_SEND_RESULT':

     proxy.response.type = proxy.MYSQLD_PACKET_ERR
     proxy.response.errmsg = "Logins are not allowed"
     return proxy.PROXY_SEND_RESULT


File: manual.info,  Node: mysql-proxy-scripting-read-auth-result,  Next: mysql-proxy-scripting-read-query,  Prev: mysql-proxy-scripting-read-auth,  Up: mysql-proxy-scripting

14.6.4.6 Accessing authentication information with `read_auth_result()'
.......................................................................

The return packet from the server during authentication is captured by
`read_auth_result()'. The only argument to this function is the
authentication packet returned by the server. As the packet is a raw
MySQL network protocol packet, you must access the first byte to
identify the packet type and contents. The `MYSQLD_PACKET_ERR' and
`MYSQLD_PACKET_OK' constants can be used to identify whether the
authentication was successful:

     function read_auth_result( auth )
             local state = auth.packet:byte()

             if state == proxy.MYSQLD_PACKET_OK then
                     print("<-- auth ok");
             elseif state == proxy.MYSQLD_PACKET_ERR then
                     print("<-- auth failed");
             else
                     print("<-- auth ... don't know: " .. string.format("%q", auth.packet));
             end
     end


File: manual.info,  Node: mysql-proxy-scripting-read-query,  Next: mysql-proxy-scripting-read-query-result,  Prev: mysql-proxy-scripting-read-auth-result,  Up: mysql-proxy-scripting

14.6.4.7 Manipulating Queries with `read_query()'
.................................................

The `read_query()' function is called once for each query submitted by
the client and accepts a single argument, the query packet that was
provided. To access the content of the packet you must parse the packet
contents manually.

For example, you can intercept a query packet and print out the
contents using the following function definition:

     function read_query( packet )
             if packet:byte() == proxy.COM_QUERY then
                     print("we got a normal query: " .. packet:sub(2))
             end
     end

This example checks the first byte of the packet to determine the type.
If the type is `COM_QUERY' (see *Note
mysql-proxy-scripting-structures-command-constants::), then we extract
the query from the packet and print it out. The structure of the packet
type supplied is important. In the case of a `COM_QUERY' packet, the
remaining contents of the packet are the text of the query string. In
this example, no changes have been made to the query or the list of
queries that will ultimately be sent to the MySQL server.

To modify a query, or add new queries, you must populate the query
queue (`proxy.queries') and then execute the queries that you have
placed into the queue. If you do not modify the original query or the
queue, then the query received from the client is sent to the MySQL
server verbatim.

When adding queries to the queue, you should follow these guidelines:

   * The packets inserted into the queue must be valid query packets.
     For each packet, you must set the initial byte to the packet type.
     If you are appending a query, you can append the query statement
     to the rest of the packet.

   * Once you add a query to the queue, the queue is used as the source
     for queries sent to the server. If you add a query to the queue to
     add more information, you must also add the original query to the
     queue or it will not be executed.

   * Once the queue has been populated, you must set the return value
     from `read_query()' to indicate whether the query queue should be
     sent to the server.

   * When you add queries to the queue, you should add an ID. The ID
     you specify is returned with the result set so that you identify
     each query and corresponding result set. The ID has no other
     purpose than as an identifier for correlating the query and
     resultset. When operating in a passive mode, during profiling for
     example, you want to identify the original query and the
     corresponding resultset so that the results expect by the client
     can be returned correctly.

   * Unless your client is designed to cope with more result sets than
     queries, you should ensure that the number of queries from the
     client match the number of results sets returned to the client.
     Using the unique ID and removing result sets you inserted will
     help.

Normally, the `read_query()' and `read_query_result()' function are
used in conjunction with each other to inject additional queries and
remove the additional result sets. However, `read_query_result()' is
only called if you populate the query queue within `read_query()'.


File: manual.info,  Node: mysql-proxy-scripting-read-query-result,  Prev: mysql-proxy-scripting-read-query,  Up: mysql-proxy-scripting

14.6.4.8 Manipulating Results with `read_query_result()'
........................................................

The `read_query_result()' is called for each result set returned by the
server only if you have manually injected queries into the query queue.
If you have not manipulated the query queue then this function is not
called.  The function supports a single argument, the result packet,
which provides a number of properties:

   * `id' -- the ID of the result set, which corresponds to the ID that
     was set when the query packet was submitted to the server when
     using `append(id)' on the query queue.

   * `query' -- the text of the original query.

   * `query_time' -- the number of microseconds required to receive the
     first row of a result set.

   * `response_time' -- the number of microseconds required to receive
     the last row of the result set.

   * `resultset' -- the content of the result set data.

By accessing the result information from the MySQL server you can
extract the results that match the queries that you injected, return
different result sets (for example, from a modified query), and even
create your own result sets.

The Lua script below, for example, will output the query, followed by
the query time and response time (i.e. the time to execute the query
and the time to return the data for the query) for each query sent to
the server:

     function read_query( packet )
             if packet:byte() == proxy.COM_QUERY then
                     print("we got a normal query: " .. packet:sub(2))

                     proxy.queries:append(1, packet )

                     return proxy.PROXY_SEND_QUERY
             end
     end

     function read_query_result(inj)
             print("query-time: " .. (inj.query_time / 1000) .. "ms")
             print("response-time: " .. (inj.response_time / 1000) .. "ms")
     end

You can access the rows of returned results from the resultset by
accessing the rows property of the resultset property of the result
that is exposed through `read_query_result()'. For example, you can
iterate over the results showing the first column from each row using
this Lua fragment:

     for row in inj.resultset.rows do
             print("injected query returned: " .. row[1])
     end

Just like `read_query()', `read_query_result()' can return different
values for each result according to the result returned. If you have
injected additional queries into the query queue, for example, then you
will want to remove the results returned from those additional queries
and only return the results from the query originally submitted by the
client.

The example below injects additional `SELECT NOW()' statements into the
query queue, giving them a different ID to the ID of the original
query. Within `read_query_result()', if the ID for the injected queries
is identified, we display the result row, and return the
`proxy.PROXY_IGNORE_RESULT' from the function so that the result is not
returned to the client. If the result is from any other query, we print
out the query time information for the query and return the default,
which passes on the result set unchanged. We could also have explicitly
returned `proxy.PROXY_IGNORE_RESULT' to the MySQL client.

     function read_query( packet )
             if packet:byte() == proxy.COM_QUERY then
                     proxy.queries:append(2, string.char(proxy.COM_QUERY) .. "SELECT NOW()" )
                     proxy.queries:append(1, packet )
                     proxy.queries:append(2, string.char(proxy.COM_QUERY) .. "SELECT NOW()" )

                     return proxy.PROXY_SEND_QUERY
             end
     end

     function read_query_result(inj)
             if inj.id == 2 then
                     for row in inj.resultset.rows do
                             print("injected query returned: " .. row[1])
                     end
                     return proxy.PROXY_IGNORE_RESULT
             else
                     print("query-time: " .. (inj.query_time / 1000) .. "ms")
                     print("response-time: " .. (inj.response_time / 1000) .. "ms")
             end
     end

For further examples, see *Note mysql-proxy-using::.


File: manual.info,  Node: mysql-proxy-using,  Next: mysql-proxy-faq,  Prev: mysql-proxy-scripting,  Up: mysql-proxy

14.6.5 Using MySQL Proxy
------------------------

* Menu:

* mysql-proxy-using-admin::      Using the Administration Interface

There are a number of different ways to use MySQL Proxy. At the most
basic level, you can allow MySQL Proxy to pass on queries from clients
to a single server. To use MySQL proxy in this mode, you just have to
specify the backend server that the proxy should connect to on the
command line:

     shell> mysql-proxy --proxy-backend-addresses=sakila:3306

If you specify multiple backend MySQL servers then the proxy will
connect each client to each server in a round-robin fashion. For
example, imagine you have two MySQL servers, A and B. The first client
to connect will be connected to server A, the second to server B, the
third to server C. For example:

     shell> mysql-proxy \
          --proxy-backend-addresses=narcissus:3306 \
          --proxy-backend-addresses=nostromo:3306

When you have specified multiple servers in this way, the proxy will
automatically identify when a MySQL server has become unavailable and
mark it accordingly. New connections will automatically be attached to
a server that is available, and a warning will be reported to the
standard output from *Note `mysql-proxy': mysql-proxy.:

     network-mysqld.c.367: connect(nostromo:3306) failed: Connection refused
     network-mysqld-proxy.c.2405: connecting to backend (nostromo:3306) failed, marking it as down for ...

Lua scripts enable a finer level of control, both over the connections
and their distribution and how queries and result sets are processed.
When using an Lua script, you must specify the name of the script on
the command line using the `--proxy-lua-script' option:

     shell> mysql-proxy --proxy-lua-script=mc.lua --proxy-backend-addresses=sakila:3306

When you specify a script, the script is not executed until a
connection is made. This means that faults with the script will not be
raised until the script is executed. Script faults will not affect the
distribution of queries to backend MySQL servers.

*Note*:

Because the script is not read until the connection is made, you can
modify the contents of the Lua script file while the proxy is still
running and the script will automatically be used for the next
connection. This ensures that MySQL Proxy remains available because it
does not have to be restarted for the changes to take effect.


File: manual.info,  Node: mysql-proxy-using-admin,  Prev: mysql-proxy-using,  Up: mysql-proxy-using

14.6.5.1 Using the Administration Interface
...........................................

The *Note `mysql-proxy': mysql-proxy. administration interface can be
accessed using any MySQL client using the standard protocols.  You can
use the administration interface to gain information about the proxy
server as a whole - standard connections to the proxy are isolated to
operate as if you were connected directly to the backend MySQL server.
Currently, the interface supports a limited set of functionality
designed to provide connection and configuration information.

Because connectivity is provided over the standard MySQL protocol, you
must access this information using SQL syntax. By default, the
administration port is configured as 4041. You can change this port
number using the `--admin-address' command-line option.

To get a list of the currently active connections to the proxy:

     mysql> select * from proxy_connections;
     +------+--------+-------+------+
     | id   | type   | state | db   |
     +------+--------+-------+------+
     |    0 | server | 0     |      |
     |    1 | proxy  | 0     |      |
     |    2 | server | 10    |      |
     +------+--------+-------+------+
     3 rows in set (0.00 sec)

To get the current configuration:

     mysql> select * from proxy_config;
     +----------------------------+----------------------+
     | option                     | value                |
     +----------------------------+----------------------+
     | admin.address              | :4041                |
     | proxy.address              | :4040                |
     | proxy.lua_script           | mc.lua               |
     | proxy.backend_addresses[0] | mysql:3306           |
     | proxy.fix_bug_25371        | 0                    |
     | proxy.profiling            | 1                    |
     +----------------------------+----------------------+
     6 rows in set (0.01 sec)


File: manual.info,  Node: mysql-proxy-faq,  Prev: mysql-proxy-using,  Up: mysql-proxy

14.6.6 MySQL Proxy FAQ
----------------------

*Questions*
   * 14.6.6.1: Is the system context switch expensive, how much
     overhead does the lua script add?

   * 14.6.6.2: How do I use a socket with MySQL Proxy? Proxy change logs
     mention that support for UNIX sockets has been added.

   * 14.6.6.3: If MySQL Proxy has to live on same machine as MySQL, are
     there any tuning considerations to ensure both perform optimally?

   * 14.6.6.4: Do proxy applications run on a separate server? If not,
     what is the overhead incurred by Proxy on the DB server side?

   * 14.6.6.5: Can MySQL Proxy handle SSL connections?

   * 14.6.6.6: What is the limit for `max-connections' on the server?

   * 14.6.6.7: As the script is re-read by proxy, does it cache this or
     is it looking at the file system with each request?

   * 14.6.6.8: With load balancing, what happen to transactions ? Are
     all queries sent to the same server ?

   * 14.6.6.9: Can I run MySQL Proxy as a daemon?

   * 14.6.6.10: What about caching the authorization info so clients
     connecting are given back-end connections that were established
     with identical authorization information, thus saving a few more
     round trips?

   * 14.6.6.11: Could MySQL Proxy be used to capture passwords?

   * 14.6.6.12: Can MySQL Proxy be used on slaves and intercept binlog
     messages?

   * 14.6.6.13: MySQL Proxy can handle about 5000 connections, what is
     the limit on a MySQL server?

   * 14.6.6.14: How does MySQL Proxy compare to DBSlayer ?

   * 14.6.6.15: I currently use SQL Relay for efficient connection
     pooling with a number of apache processes connecting to a MySQL
     server. Can MySQL proxy currently accomplish this. My goal is to
     minimize connection latency while keeping temporary tables
     available.

   * 14.6.6.16: The global namespace variable example with quotas does
     not persist after a reboot, is that correct?

   * 14.6.6.17: I tried using MySQL Proxy without any Lua script to try
     a round-robin type load balancing. In this case, if the first
     database in the list is down, MySQL Proxy would not connect the
     client to the second database in the list.

   * 14.6.6.18: Would the Java-only connection pooling solution work for
     multiple web servers? With this, I'd assume you can pool across
     many web servers at once?

   * 14.6.6.19: Is the MySQL Proxy an API ?

   * 14.6.6.20: If you have multiple databases on the same box, can you
     use proxy to connect to databases on default port 3306?

   * 14.6.6.21: Will Proxy be deprecated for use with connection
     pooling once MySQL 6.x comes out? Or will 6.x integrate proxy more
     deeply?

   * 14.6.6.22: In load balancing, how can I separate reads from writes?

   * 14.6.6.23: We've looked at using MySQL Proxy but we're concerned
     about the alpha status - when do you think the proxy would be
     considered production ready?

   * 14.6.6.24: Will the proxy road map involve moving popular features
     from lua to C? For example Read/Write splitting

   * 14.6.6.25: Are these reserved function names (e.g., error_result)
     that get automatically called?

   * 14.6.6.26: Can you explain the status of your work with
     `memcached' and MySQL Proxy?

   * 14.6.6.27: Is there any big web site using MySQL Proxy ? For what
     purpose and what transaction rate have they achieved.

   * 14.6.6.28: So the authentication when connection pooling has to be
     done at every connection? What's the authentication latency?

   * 14.6.6.29: Is it possible to use the MySQL proxy w/ updating a
     Lucene index (or Solr) by making TCP calls to that server to
     update?

   * 14.6.6.30: Isn't MySQL Proxy similar to what is provided by Java
     connection pools?

   * 14.6.6.31: Are there tools for isolating problems? How can someone
     figure out if a problem is in the client, in the db or in the
     proxy?

   * 14.6.6.32: Can you dynamically reconfigure the pool of MySQL
     servers that MySQL Proxy will load balance to?

   * 14.6.6.33: Given that there is a `connect_server' function, can a
     Lua script link up with multiple servers?

   * 14.6.6.34: Adding a proxy must add latency to the connection, how
     big is that latency?

   * 14.6.6.35: In the quick poll, I see "Load Balancer: read-write
     splitting" as an option, so would it be correct to say that there
     are no scripts written for Proxy yet to do this?

   * 14.6.6.36: Is it "safe" to use `LuaSocket' with proxy scripts?

   * 14.6.6.37: How different is MySQL Proxy from DBCP (Database
     connection pooling) for Apache in terms of connection pooling?

   * 14.6.6.38: Do you have make one large script and call at proxy
     startup, can I change scripts without stopping and restarting
     (interrupting) the proxy?

*Questions and Answers* *14.6.6.1: ** Is the system context switch
expensive, how much overhead does the lua script add?  *

Lua is fast and the overhead should be small enough for most
applications. The raw packet-overhead is around 400 microseconds.

*14.6.6.2: ** How do I use a socket with MySQL Proxy? Proxy change logs
mention that support for UNIX sockets has been added.  *

Just specify the path to the socket:

     --proxy-backend-addresses=/path/to/socket

However it appears that `--proxy-address=/path/to/socket' does not work
on the front end. It would be nice if someone added this feature.

*14.6.6.3: ** If MySQL Proxy has to live on same machine as MySQL, are
there any tuning considerations to ensure both perform optimally?  *

MySQL Proxy can live on any box: application, db or its own box.  MySQL
Proxy uses comparatively little CPU or RAM, so additional requirements
or overhead is negligible.

*14.6.6.4: ** Do proxy applications run on a separate server? If not,
what is the overhead incurred by Proxy on the DB server side?  *

You can run the proxy on the application server, on its own box or on
the DB-server depending on the use-case

*14.6.6.5: ** Can MySQL Proxy handle SSL connections?  *

No, being the man-in-the-middle, Proxy can't handle encrypted sessions
because it cannot share the SSL information.

*14.6.6.6: ** What is the limit for `max-connections' on the server?  *

Around 1024 connections the MySQL Server may run out of threads it can
spawn. Leaving it at around 100 is advised.

*14.6.6.7: ** As the script is re-read by proxy, does it cache this or
is it looking at the file system with each request?  *

It looks for the script at client-connect and reads it if it has
changed, otherwise it uses the cached version.

*14.6.6.8: ** With load balancing, what happen to transactions ? Are all
queries sent to the same server ?  *

Without any special customization the whole connection is sent to the
same server. That keeps the whole connection state intact.

*14.6.6.9: ** Can I run MySQL Proxy as a daemon?  *

Starting from version 0.6.0, the Proxy is launched as a daemon by
default. If you want to avoid this, use the `-D' or `--no-daemon'
option.  To keep track of the process ID, the daemon can be started with
the additional option `--pid-file=file', to save the PID to a known
file name. On version 0.5.x, the Proxy can't be started natively as a
daemon

*14.6.6.10: ** What about caching the authorization info so clients
connecting are given back-end connections that were established with
identical authorization information, thus saving a few more round trips?
*

There is an option that provides this functionality `
--proxy-pool-no-change-user'.

*14.6.6.11: ** Could MySQL Proxy be used to capture passwords?  *

The MySQL network protocol does not allow passwords to be sent in
clear-text, all you could capture is the encrypted version.

*14.6.6.12: ** Can MySQL Proxy be used on slaves and intercept binlog
messages?  *

We are working on that. See
`http://jan.kneschke.de/2008/5/30/mysql-proxy-rbr-to-sbr-decoding' for
an example.

*14.6.6.13: ** MySQL Proxy can handle about 5000 connections, what is
the limit on a MySQL server?  *

Se your `max-connections' settings. By default the setting is 150, the
proxy can handle a lot more.

*14.6.6.14: ** How does MySQL Proxy compare to DBSlayer ?  *

DBSlayer is a REST->MySQL tool, MySQL Proxy is transparent to your
application. No change to the application is needed.

*14.6.6.15: ** I currently use SQL Relay for efficient connection
pooling with a number of apache processes connecting to a MySQL server.
Can MySQL proxy currently accomplish this. My goal is to minimize
connection latency while keeping temporary tables available.  *

Yes.

*14.6.6.16: ** The global namespace variable example with quotas does
not persist after a reboot, is that correct?  *

Yes. if you restart the proxy, you lose the results, unless you save
them in a file.

*14.6.6.17: ** I tried using MySQL Proxy without any Lua script to try a
round-robin type load balancing. In this case, if the first database in
the list is down, MySQL Proxy would not connect the client to the
second database in the list.  *

This issue is fixed in version 0.7.0.

*14.6.6.18: ** Would the Java-only connection pooling solution work for
multiple web servers? With this, I'd assume you can pool across many
web servers at once?  *

Yes. But you can also start one proxy on each application server to get
a similar behaviour as you have it already.

*14.6.6.19: ** Is the MySQL Proxy an API ?  *

No, MySQL Proxy is an application that forwards packets from a client
to a server using the MySQL network protocol. The MySQL proxy provides
a API allowing you to change its behaviour.

*14.6.6.20: ** If you have multiple databases on the same box, can you
use proxy to connect to databases on default port 3306?  *

Yes, MySQL Proxy can listen on any port. Providing none of the MySQL
servers are listening on the same port.

*14.6.6.21: ** Will Proxy be deprecated for use with connection pooling
once MySQL 6.x comes out? Or will 6.x integrate proxy more deeply?  *

The logic about the pooling is controlled by the lua scripts, you can
enable and disable it if you like. There are no plans to embed the
current MySQL Proxy functionality into the MySQL Server.

*14.6.6.22: ** In load balancing, how can I separate reads from writes?
*

There is no automatic separation of queries that perform reads or
writes to the different backend servers. However, you can specify to
*Note `mysql-proxy': mysql-proxy. that one or more of the 'backend'
MyuSQL servers are read-only.

     $ mysql-proxy \
     --proxy-backend-addresses=10.0.1.2:3306 \
     --proxy-read-only-backend-addresses=10.0.1.3:3306 &

In the next releases we will add connection pooling and read/write
splitting to make this more useful. See also MySQL Load Balancer
(http://dev.mysql.com/doc/refman/5.1/en/load-balancer.html).

*14.6.6.23: ** We've looked at using MySQL Proxy but we're concerned
about the alpha status - when do you think the proxy would be considered
production ready?  *

We are on the road to the next feature release: 0.7.0. It will improve
the performance quite a bit. After that we may be able to enter the
beta phase.

*14.6.6.24: ** Will the proxy road map involve moving popular features
from lua to C? For example Read/Write splitting *

We will keep the high-level parts in the Lua layer to be able to adjust
to special situations without a rebuild. Read/Write splitting sometimes
needs external knowledge that may only be available by the DBA.

*14.6.6.25: ** Are these reserved function names (e.g., error_result)
that get automatically called?  *

Only functions and values starting with `proxy.*' are provided by the
proxy. All others are provided by you.

*14.6.6.26: ** Can you explain the status of your work with `memcached'
and MySQL Proxy?  *

There are some ideas to integrate proxy and `memcache' a bit, but no
code yet.

*14.6.6.27: ** Is there any big web site using MySQL Proxy ? For what
purpose and what transaction rate have they achieved.  *

Yes, gaiaonline (http://gaiaonline.com/).  They have tested MySQL Proxy
and seen it handle 2400 queries per second through the proxy.

*14.6.6.28: ** So the authentication when connection pooling has to be
done at every connection? What's the authentication latency?  *

You can skip the round-trip and use the connection as it was added to
the pool. As long as the application cleans up the temporary tables it
used. The overhead is (as always) around 400 microseconds.

*14.6.6.29: ** Is it possible to use the MySQL proxy w/ updating a
Lucene index (or Solr) by making TCP calls to that server to update?  *

Yes, but it isn't advised for now.

*14.6.6.30: ** Isn't MySQL Proxy similar to what is provided by Java
connection pools?  *

Yes and no. Java connection pools are specific to Java applications,
MySQL Proxy works with any client API that talks the MySQL network
protocol. Also, connection pools do not provide any functionality for
intelligently examining the network packets and modifying the contents.

*14.6.6.31: ** Are there tools for isolating problems? How can someone
figure out if a problem is in the client, in the db or in the proxy?  *

You can set a debug script in the proxy, which is an exceptionally good
tool for this purpose. You can see very clearly which component is
causing the problem, if you set the right breakpoints.

*14.6.6.32: ** Can you dynamically reconfigure the pool of MySQL
servers that MySQL Proxy will load balance to?  *

Not yet, it is on the list. We are working on a administration
interface for that purpose.

*14.6.6.33: ** Given that there is a `connect_server' function, can a
Lua script link up with multiple servers?  *

The proxy provides some tutorials in the source-package, one is
`examples/tutorial-keepalive.lua'.

*14.6.6.34: ** Adding a proxy must add latency to the connection, how
big is that latency?  *

In the range of 400microseconds

*14.6.6.35: ** In the quick poll, I see "Load Balancer: read-write
splitting" as an option, so would it be correct to say that there are no
scripts written for Proxy yet to do this?  *

There is a proof of concept script for that included. But its far from
perfect and may not work for you yet.

*14.6.6.36: ** Is it "safe" to use `LuaSocket' with proxy scripts?  *

You can, but it is not advised as it may block.

*14.6.6.37: ** How different is MySQL Proxy from DBCP (Database
connection pooling) for Apache in terms of connection pooling?  *

Connection Pooling is just one use-case of the MySQL Proxy. You can use
it for a lot more and it works in cases where you can't use DBCP (like
if you don't have Java).

*14.6.6.38: ** Do you have make one large script and call at proxy
startup, can I change scripts without stopping and restarting
(interrupting) the proxy?  *

You can just change the script and the proxy will reload it when a
client connects.


File: manual.info,  Node: mem-introduction,  Next: replication,  Prev: ha-overview,  Up: Top

15 MySQL Enterprise Monitor
***************************

* Menu:

* mem-overview::                 An Overview of the Service
* mem-conventions::              Conventions Used in This Document
* mem-install::                  Installation and Upgrades
* mem-deployment::               Deploying MySQL Enterprise Service Manager
* mem-dashboard::                MySQL Enterprise Dashboard
* mem-dashboard-settings::       The Settings Page
* mem-advisors::                 The Advisors Page
* mem-events::                   The Events Page
* mem-graphs::                   The Graphs Page
* mem-query-analysis::           The Query Analyzer Page
* mem-replication::              The Replication Page
* mem-faq::                      MySQL Enterprise Monitor Frequently Asked Questions

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

The MySQL Enterprise Monitor serves as an automated assistant for MySQL
database administrators. This service is designed to help
administrators with their day-to-day tasks by monitoring MySQL servers
and identifying potential problems. These features are designed to save
the database administrator's time and effort by providing the
information you need through a simplified interface.

An extension of existing MySQL Enterprise services, MySQL Enterprise
Monitor monitors enterprise database environments and provides expert
advice on how customers can tighten security and optimize the
performance and uptime of their MySQL servers.

MySQL Enterprise Monitor helps administrators:

   * Intelligently stay up to date with releases and bug fixes

   * Know what's going on with their system

   * Manage day-to-day database maintenance tasks

   * Improve the performance of their system

   * Manage and prevent crises

The MySQL Enterprise Monitor was designed to tackle the job of managing
the performance of any number of MySQL database servers, regardless of
their physical or geographical location. Although MySQL Enterprise
Monitor can easily track just a handful of MySQL servers, the service is
specifically designed to greatly curtail the time it takes to get a
handle on the availability and performance levels of many database
servers at once.

The MySQL Enterprise Monitor does this by providing an web-based
interface -- called the Enterprise Dashboard -- that serves as the
portal for viewing information about your MySQL database servers. MySQL
professionals can manage all their servers by group or individually if
need be.

The Enterprise Dashboard web interface does not have to be installed on
individual desktops, but is instead available from a centrally located
machine that serves as the main location for the Monitoring and
Advisory service.


File: manual.info,  Node: mem-overview,  Next: mem-conventions,  Prev: mem-introduction,  Up: mem-introduction

15.1 An Overview of the Service
===============================

* Menu:

* mem-service-architecture::     The Service Architecture
* mem-features::                 Service Features
* mem-security::                 Security

The MySQL Enterprise Monitor is a collection of components that work
together to monitor and help administer your MySQL server
installations. This service includes server management agents,
advisors, and a central MySQL Enterprise Service Manager, all working
in tandem with the MySQL Enterprise to keep your MySQL servers secure
and up to date. All of this is controlled through the MySQL Enterprise
Dashboard -- a lightweight web-based interface that gives you complete
control of your MySQL servers from any location.

FIGURE GOES HERE: MySQL Enterprise Monitor Architecture

The service is made up of a number of components, including the Monitor
Agent (MySQL Enterprise Monitor Agent), the Service Manager (MySQL
Enterprise Service Manager), the Enterprise Dashboard, the Repository
and the Advisors.


File: manual.info,  Node: mem-service-architecture,  Next: mem-features,  Prev: mem-overview,  Up: mem-overview

15.1.1 The Service Architecture
-------------------------------

The MySQL Enterprise Monitor is powered by a distributed web-based
application that is deployed within the confines of the corporate
firewall.  The Enterprise Dashboard provides the interface to the server
data, advisor notifications, live information and communication with
the MySQL Enterprise Update Service.

Subscribers are kept up to date about the latest releases of the MySQL
server or issues that may affect their specific implementation of MySQL
by using the MySQL Enterprise Update Service. This same mechanism is
used to notify MySQL Enterprise Monitor users of updates to the
application or to the MySQL Advisors and Rules.  The various components
are described below.

   * *Monitor Agent*

     Monitor Agents are the foot soldiers of the MySQL Enterprise
     Monitor; they monitor each MySQL server. Running as a Windows
     service or Unix daemon, the Agent uses a combination of MySQL
     specific commands, SQL queries, and custom scripts to collect and
     report MySQL server or operating system (OS) specific data.  The
     Monitor Agent initiates a `heartbeat' to the Service Manager on a
     regular basis to ensure specific MySQL server and OS level data
     collections are current.

     In the overall architecture, the Monitor Agent is the only
     component of the MySQL Enterprise Monitor that establishes or
     maintains a connection with the monitored MySQL Server. As with any
     MySQL client, the Monitor Agent is authenticated on the monitored
     MySQL server and requires a user name and password to establish a
     connection.

     In addition, the MySQL Enterprise Monitor Agent also provides a
     proxy service that allows for information about queries to be
     captured and reported as part of the Query Analyzer functionality.
     The MySQL Enterprise Monitor Agent accepts client connections and
     forwards the SQL statements on to the server and returns the
     results. In the background, the agent is collecting information
     about the query execution, row counts, times and other data so
     that queries and their execution can be monitored.

   * *Service Manager*

     The Service Manager is the heart and soul of the MySQL Enterprise
     Monitor.  It is built on a collection of Java services hosted on a
     single Windows or Unix server. The Service Manager interacts with
     all of the Monitor Agents under its domain to collect MySQL server
     and OS level data for each of the monitored MySQL servers.

     The Service Manager performs many duties including:

        * Enterprise Dashboard, the main interface to the MySQL
          Enterprise Service Manager.

        * Autodiscovery of monitored MySQL Servers.

        * Creation and management of Monitor Agent tasks.

        * Storage of data collections from Monitor Agents.

        * Monitoring of key MySQL server and OS level metric data
          collections.

        * Reporting MySQL best practice events and violations.

        * Providing MySQL expert advice for MySQL best practice
          violations.

        * Autodiscovery of replication topology (Not available for all
          subscription levels)

   * *The Repository*

     The Repository is built on MySQL 5.0.X and is used to store MySQL
     server and OS level data collections for each of the monitored
     MySQL Servers. This information is used by the Service Manager to
     evaluate and report the health and status of the monitored MySQL
     environment(s).

   * *The Enterprise Dashboard*

     The MySQL Enterprise web client provides the graphical user
     interface (GUI) for the MySQL Enterprise Monitor. This interface
     is the primary means of monitoring the state of your MySQL servers,
     identifying rule violations and providing advice on how best to
     address and correct any underlying issues.

     This interface also provides an easy means of configuring
     advisors, adding users, creating notification groups, and
     receiving updates from MySQL Enterprise.


File: manual.info,  Node: mem-features,  Next: mem-security,  Prev: mem-service-architecture,  Up: mem-overview

15.1.2 Service Features
-----------------------

The key features of the MySQL Enterprise Monitor can be summarized as
follows:

   * Group-level or Server-level management options

   * Enterprise Dashboard for managing all MySQL Servers from a
     consolidated console

   * Monitoring page for `at a glance' global health check of key
     systems

   * MySQL-provided Advisors and Advisor Rules for enforcing MySQL Best
     Practices

   * Advisor Rule Scheduling for unattended operations

   * Customizable Thresholds and Alerts for identifying Advisor Rule
     violations

   * User-Defined Advisor Rules

   * Event/Alert History browser for researching advisor-specific
     events and annotations

   * Query Analyzer functionality allowing you to monitor the execution
     times, row counts and other data about queries executed on your
     MySQL server.

These features are presented through the MySQL Enterprise Dashboard
which is made up of six main pages:

   * The `Monitor' page comprises:

        * The `Server Tree': Easily navigate monitored servers

        * The `Graphing': This capability is built in so you can
          quickly assess critical functions such as activity,
          performance metrics, and number of connections

        * The `Heat Chart': Color-coded buttons provide key operating
          system and database metrics

   * The `Advisors' page

     This page shows the advisors that are currently scheduled.  There
     are advisors for a variety of topics such as security and
     indexing. Users can add, edit, or create their own advisors.

   * The `Events' page

     This page shows rule violations, indicating the server, severity,
     and time of occurrence. A number of filter options are available,
     allowing various views of events.

   * The `Graphs' page

     Use this page to view all the available graphs and to adjust the
     scale of the graphs, for a more or less detailed view as the
     situation requires.

   * The `Query Analyzer' page

   * The `Replication' page

     Use this page to keep track of your masters and their slaves (Not
     available for all subscription levels)

   * The `Settings' page

     On this page you configure servers, users, email addresses, and
     notification groups. Entering a user name and password for MySQL
     Enterprise provides automatic updates.


File: manual.info,  Node: mem-security,  Prev: mem-features,  Up: mem-overview

15.1.3 Security
---------------

Using the Tomcat/Apache web server for the user interface allows an
administrator to configure the web server to meet any security
regulations. The MySQL Enterprise Monitor architecture is designed to
be as secure as possible, even when monitoring systems outside of the
local network.

Communications between the MySQL Enterprise Monitor Agent and MySQL
Enterprise Service Manager can be protected by Secure Socket Layer
(SSL) encryption and server and agent can use SSL certificates to
provide authentication and prevent spoofing.

The MySQL Enterprise Monitor Agent is like a web browser--it is an HTTP
client application that initiates all communication with the MySQL
Enterprise Service Manager. If the server requires action from the
agent, it must wait until the agent next initiates contact and sends
its request in a response. This means you do not need to open an
inbound port on the machine on which the agent is running because it
does not listen for requests. However, an outbound port must be open
for the agent to contact the MySQL Enterprise Service Manager.

As an additional security feature, each Agent can have a separate
Advisory Service login which minimizes exposure should any one agent be
compromised.


File: manual.info,  Node: mem-conventions,  Next: mem-install,  Prev: mem-overview,  Up: mem-introduction

15.2 Conventions Used in This Document
======================================

This document uses certain typographical conventions:

   * `Text in this style' is used for SQL statements; database, table,
     and column names; program listings and source code; and
     environment variables. Example: `To reload the grant tables, use
     the `FLUSH PRIVILEGES' statement.'

   * Text in this style indicates input that you type in examples.

   * `Text in this style' indicates the names of executable programs
     and scripts, examples being *Note `mysql': mysql. (the MySQL
     command line client program) and *Note `mysqld': mysqld. (the
     MySQL server executable).

   * TEXT IN THIS STYLE is used for variable input for which you should
     substitute a value of your own choosing.

   * File names and directory names are written like this: `The global
     `my.cnf' file is located in the `/etc' directory.'

   * Character sequences are written like this: `To specify a wildcard,
     use the ``%'' character.'

   * _Text in this style_ is used for emphasis.

   * *Text in this style* is used in table headings and to convey
     especially strong emphasis.

When commands are shown that are meant to be executed from within a
particular program, the prompt shown preceding the command indicates
which command to use. For example, `shell>' indicates a command that
you execute from your login shell or from the command line in Windows:

     shell> type a shell command here

The `shell' is your command interpreter. On Unix, this is typically a
program such as `sh', `csh', or `bash'. On Windows, the equivalent
program is `command.com' or `cmd.exe', typically run in a console
window.

When you enter a command or statement shown in an example, do not type
the prompt shown in the example.

Sometimes, what appears on one line in a console window cannot be
represented in the documentation on a single line. In cases such as
this the character ``»'' is used. For example:

     Please specify the directory where the MySQL Enterprise Monitor Â»
      will be installed.

Where Unix commands are concerned, the continuation character ``\'' is
used. Doing this allows commands to be copied and pasted to the command
line verbatim. For example:

     shell> /opt/mysql/enterprise/agent/bin/mysql-monitor-agent -f \
      /opt/mysql/enterprise/agent/etc/mysql-monitor-agent.ini

SQL keywords are not case sensitive and may be written in either case.
This document uses uppercase.

In syntax descriptions, square brackets (``['' and ``]'') indicate
optional words or clauses. For example, in the following statement, `IF
EXISTS' is optional:

     DROP TABLE [IF EXISTS] TBL_NAME

When a syntax element consists of a number of alternatives, the
alternatives are separated by vertical bars (``|''). When one member
from a set of choices _may_ be chosen, the alternatives are listed
within square brackets (``['' and ``]''):

     TRIM([[BOTH | LEADING | TRAILING] [REMSTR] FROM] STR)

When one member from a set of choices _must_ be chosen, the
alternatives are listed within braces (``{'' and ``}''):

     {DESCRIBE | DESC} TBL_NAME [COL_NAME | WILD]

An ellipsis (`...') indicates the omission of a section of a statement,
typically to provide a shorter version of more complex syntax. For
example, `INSERT ...  SELECT' is shorthand for the form of `INSERT'
statement that is followed by a `SELECT' statement.

An ellipsis can also indicate that the preceding syntax element of a
statement may be repeated. In the following example, multiple
RESET_OPTION values may be given, with each of those after the first
preceded by commas:

     RESET RESET_OPTION [,RESET_OPTION] ...

Commands for setting shell variables are shown using Bourne shell
syntax. For example, the sequence to set the `CC' environment variable
and run the `configure' command looks like this in Bourne shell syntax:

     shell> CC=gcc ./configure

If you are using `csh' or `tcsh', you must issue commands somewhat
differently:

     shell> setenv CC gcc
     shell> ./configure

Throughout this document the term ``Unix'' is used to describe any Unix
or Unix-like operating system. For an up-to-date list of operating
systems supported by the MySQL Enterprise Monitor please see the MySQL
Enterprise web site (https://enterprise.mysql.com/).


File: manual.info,  Node: mem-install,  Next: mem-deployment,  Prev: mem-conventions,  Up: mem-introduction

15.3 Installation and Upgrades
==============================

* Menu:

* mem-user-roles::               User Roles
* mem-install-server::           Service Manager Installation
* mem-install-agent::            Monitor Agent Installation
* mem-unattended-installation::  Unattended Installation
* mem-install-post-installation::  Post-Installation Considerations
* mem-upgradeorchange::          Upgrading, Re-Installing or Changing Your Installation
* mem-uninstall::                Uninstalling the MySQL Enterprise Monitor

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

This chapter describes the process of installing the MySQL Enterprise
Monitor on all operating systems. A working installation requires the
installation of a MySQL Enterprise Service Manager, the MySQL
Enterprise Advisors and one or more MySQL Enterprise Monitor Agents.
Simply described, the agent inspects the MySQL server it is monitoring,
reports to the Service Manager, and the results are interpreted by the
advisors and displayed in the MySQL Enterprise Dashboard for viewing in
a web browser.

One Monitor Agent is installed for each MySQL server that is being
monitored. The Monitor Agent usually runs on the same machine that
hosts the monitored MySQL server but it may run on any machine that has
access to both the monitored MySQL server and the MySQL Enterprise
Dashboard. The agent reports its findings to the Service Manager and
these results are interpreted by Advisors and displayed in the
dashboard. The end user opens a web browser to view the information
presented in the dashboard. The Service Manager and dashboard run on
the same machine and both have access to a local MySQL server installed
as part of the MySQL Enterprise Monitor. This server is known as the
repository and provides storage for the data provided by the agent.

Installation is a three step process:

  1. Install and start the Service Manager on the monitoring system.

  2. Configure the Service Manager and install the Advisors.

  3. Install and start the Monitor Agent to monitor the targeted MySQL
     server.

*Installation Requirements*

The Service Manager is available for Windows, Mac OS X, and a variety
of Unix and Linux operating systems.

*Note*:

The Mac OS X Service Manager is only supported on Intel architecture.
However, the Mac OS X agent is supported for both Intel and the PowerPC.

To install the MySQL Enterprise Monitor on Windows requires
approximately 260 MB of space and approximately 450 MB on Unix, Linux
and Mac OS X. The installer checks that there is enough free space on
the destination disk. However, disk space usage will increase with time
since the repository stores historical data.

The minimum recommended requirements for the service manager are at
least a 2GHz CPU and at least 1GB of RAM. If you are monitoring a large
number of services, then there will be an increased load on the server
manager. Running the service manager on a machine that is already
running other tasks is only recommended if you are monitoring a small
number of agents. For monitor five or more agents simultaneously, you
should dedicate a machine to the process.

For more information, see *Note mem-deployment-config::.

The Monitor Agent is available for a wide range of operating systems.
For an up-to-date list please see the MySQL Enterprise web site
(https://enterprise.mysql.com/). The agent can be used to monitor any
MySQL server from version 4.0.x through 6.0.x.


File: manual.info,  Node: mem-user-roles,  Next: mem-install-server,  Prev: mem-install,  Up: mem-install

15.3.1 User Roles
-----------------

* Menu:

* mem-existing-users::           Existing Users
* mem-created-users::            User Created During Installation
* mem-users-created-first-login::  Users Created on First Log-in

Prior to installation you will need to have at hand credentials for
access to the MySQL server you plan to monitor and also your MySQL
Enterprise credentials. _During_ installation and when first logging
in, you will set up a variety of users with different roles and
credentials. This can become confusing. This section outlines the
various users associated with the MySQL Enterprise Monitor and gives a
brief description of their roles.


File: manual.info,  Node: mem-existing-users,  Next: mem-created-users,  Prev: mem-user-roles,  Up: mem-user-roles

15.3.1.1 Existing Users
.......................

The *MySQL Enterprise user* - These are the credentials you use to log
in to the MySQL Enterprise web site. You will need them in order to
acquire the Advisor files and receive updates and, if necessary,
acquire a product key.

The *MySQL user* - For Monitor Agents to report the status of a MySQL
server they must have privileges on that server. To perform all
functions an agent must have `SHOW DATABASES', `REPLICATION CLIENT',
`SUPER', `CREATE', and `SELECT' privileges. In short, the Monitor Agent
needs to have read access to all data. Details about this account are
given in *Note mem-agent-rights::.


File: manual.info,  Node: mem-created-users,  Next: mem-users-created-first-login,  Prev: mem-existing-users,  Up: mem-user-roles

15.3.1.2 User Created During Installation
.........................................

The *Repository user* - This user is the only user in the `user' table
in the `mysql' database in the bundled MySQL server. To avoid confusion
with monitored MySQL servers, this server is referred to throughout
this document as the `repository'. The repository user can log in from
`localhost' using the password specified during installation and has
all privileges on all databases.  These credentials are used to create
the repository and its tables and to record data in them. During
installation the default value for the user name for this role is
`service_manager'. No default password is specified. You can use these
credentials to manage the repository from the command line or when
using a program such as MySQL Administrator.

During installation the file `configuration_report.txt' is created.
Reference this file for the credentials of the repository manager.
After the MySQL Enterprise Service Manager is installed, look for this
file in the following directories:

   * Windows - `C:\Program Files\MySQL\Enterprise\Monitor'

   * Unix - `/opt/mysql/enterprise/monitor'

   * Mac OS X - `/Applications/mysql/enterprise/monitor'


File: manual.info,  Node: mem-users-created-first-login,  Prev: mem-created-users,  Up: mem-user-roles

15.3.1.3 Users Created on First Log-in
......................................

The *Root user* - This user is the administrator of the dashboard. The
first time you log in to the dashboard you must log in as this user.
The default user name for this user is `admin'. There is no default
password for this user.

The *Agent user* - The Monitor Agent needs to report the status of the
MySQL server it is monitoring. For this reason it needs to log in to the
dashboard. The default user name for this user is `agent'. There is no
default password for this user.

*Note*:

The Monitor Agent has two roles in the MySQL Enterprise Monitor; it
must have access to the dashboard and to the MySQL server it is
monitoring. For a description of the agent as a MySQL user see *Note
mem-existing-users::.


File: manual.info,  Node: mem-install-server,  Next: mem-install-agent,  Prev: mem-user-roles,  Up: mem-install

15.3.2 Service Manager Installation
-----------------------------------

* Menu:

* mem-server-install-generic::   Service Manager Installation Common Parameters
* mem-server-install-windows::   Service Manager Installation on Windows
* mem-server-install-osx::       Service Manager Installation on Mac OS X
* mem-server-install-unix::      Service Manager Installation on Unix
* mem-server-starting-windows::  Starting/Stopping the MySQL Enterprise Monitor Service on Windows
* mem-server-starting-unix-osx::  Starting/Stopping the MySQL Enterprise Monitor Service on Unix and Mac OS X
* mem-server-initial-config::    MySQL Enterprise Service Manager Configuration Settings and Advisor Installation

The MySQL Enterprise Service Manager is the core element of the MySQL
Enterprise Monitor. The installation process for this element is
completely self-contained, but the installation includes the following
components:

   * Apache Tomcat

   * MySQL Server

   * Java VM

*Note*:

After installation you can determine the version number of the various
components by entering
`http://SERVER_NAME:18080/main?command=list_versions' into the web
browsers address bar.

During installation, versions of MySQL and Tomcat will be installed
onto the machine. The installer automatically provides default network
ports that are different from standard installation for these
applications. You can change the ports during installation.

During installation, default values are shown for user names and ports.
This is for your convenience only; you may choose different values. The
installer detect ports that are already in use and allows you to select
different ports.

*Warning*:

The MySQL Enterprise Service Manager version 2.0 requires agents using
2.0 or higher.

All the installations share the same basic configuration parameters
that you will be asked to confirm during installation. Before you start
your installation, please review the section on these common
paramaters, then proceed to section specific to your installation
platform. For details of the common parameters, see *Note
mem-server-install-generic::. For information on installation under
Windows, see *Note mem-server-install-windows::, for Mac OS X see *Note
mem-server-install-osx::, and for Unix/Linux, see *Note
mem-server-install-unix::.


File: manual.info,  Node: mem-server-install-generic,  Next: mem-server-install-windows,  Prev: mem-install-server,  Up: mem-install-server

15.3.2.1 Service Manager Installation Common Parameters
.......................................................

All installations of the Service Manager install the Tomcat and MySQL
applications using the same basic set of parameters. The defaults
provided by the installation process are designed to be unique so that
they do not interfere with existing installations of either product.
However, you should check these parameters before installation to
ensure that you do not experience any problems.

The common parameters are divided into those applying to the Tomcat
server, and the MySQL server (Repository Configuration):

   * *Tomcat Server Options*

        * Tomcat Server port -- the default port that the Tomcat server
          will use when listening for connections. If you change this
          option, then the port that you need to use when connecting to
          the Service Manager must be modified accordingly. The default
          value is 18080.

          *Note*:

          If you are not currently running a web server on port 80 you
          may find it more convenient to use the well known port rather
          than `18080'. Since port `80' is the default for a web server,
          you can then open the dashboard without specifying a port.

        * Tomcat Shutdown port --the port used by the management
          scripts that is used to shut the Tomcat server down when you
          need to stop the Service Manager. The default value is 18005.

        * Tomcat SSL Port -- the standard port used to connect to the
          Service Manager when you want to use Secure Sockets Layer
          (SSL) encrypted communication. The default value is 18443.

   * *Repository Configuration (MySQL Server)*

        * Repository Username -- the user name created and used to
          store information within the MySQL server to hold the
          information used by the Service Manager. In normal use, you
          should not need to use or modify this information, but it may
          be required if you have a support issue. The default value is
          `service_manager'.

        * Repository User password -- the password to be used for the
          Repository Username. This should be set to a secure password
          so that the repository data is secure.

The information that you configure during installation will always be
recorded within the `configuration_report.txt' file within the
installation directory for the Service Manager.

*Caution*:

Because the information stored within the `configuration_report.txt'
file is in plain text, the Repository user name and password
information are also exposed within this file. Make sure that the
installation directory and file are secure that they can only be
accessed by those users who would need to use the information.


File: manual.info,  Node: mem-server-install-windows,  Next: mem-server-install-osx,  Prev: mem-server-install-generic,  Up: mem-install-server

15.3.2.2 Service Manager Installation on Windows
................................................

On Windows the installation modes are `win32' and `unattended' only.
`unattended' mode is especially useful if you are doing multiple
installations.  For more information on this topic see *Note
mem-unattended-installation::.

*Note*:

In order to install the Service Manager as a Windows service, you must
do the installation as a privileged user.

On Windows Vista, if user account control is on, an operating system
dialog box requests confirmation of the installation.

To install the Service Manager on Windows, find the executable file
named `mysqlmonitor-VERSION-windows-installer.exe' (where VERSION
represents the three-part version number).

  1. Double click on the MySQL Monitor installer. You should be
     presented with the Language Selection prompt. Select the language
     to use for the installer and then click `OK'.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Monitor on
     Windows: Language Selection

  2. With the installation language selected, the remainder of the
     installation sets up the installation location and the main
     configuration parameters required by MySQL Enterprise Service
     Manager. Click `Next' to continue.

  3. Select the installation directory where you want the MySQL
     Enterprise Service Manager components installed. By default on
     Windows the directory is `C:\Program
     Files\MySQL\Enterprise\Monitor'. You click the button next to the
     installation directory field to select a directory using the File
     chooser, or type the directory manually. Click `Next' to continue.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Monitor on
     Windows: Installation Directory

  4. Configure the options that set the network ports used by the
     Tomcat server. For more information, see *Note
     mem-server-install-generic::. Click `Next' to continue.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Monitor on
     Windows: Tomcat Server Options

  5. Configure the repository settings, setting the user name, password
     and port used to communicate with the bundled MySQL server that
     will be used to store the information and statistics for your
     installation. For more information, see *Note
     mem-server-install-generic::. Click `Next' to continue.

     *Note*:

     If the Windows firewall is enabled you will be asked to unblock
     ports for Apache/Tomcat and the MySQL server.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Monitor on
     Windows: Repository Configuration

  6. You will be provided with information and a warning about the
     configuration options and how they are stored in the
     `configuration_report.txt' file, and it's location. Take a note of
     the full path to this file in case you need to look up the
     information later. Click `Next' to continue.

  7. You should now be prompted to start the installation process.
     Click `Next' to continue.

  8. Once the installation has been completed, you will be provided
     with the information on how to uninstall MySQL Enterprise Service
     Manager.  Click `Next' to continue.

  9. To complete the installation and set up your MySQL Enterprise
     Service Manager, you will need to login to the Dashboard. You can
     do this automatically by checking the box on the final window
     before clicking `Finish'. This checkbox is selected by default. If
     you do not want to run the Dashboard at this time, uncheck the box
     and clock `Finish'.

For instructions on starting the MySQL Enterprise Monitor services
under Windows, see *Note mem-server-starting-windows::.


File: manual.info,  Node: mem-server-install-osx,  Next: mem-server-install-unix,  Prev: mem-server-install-windows,  Up: mem-install-server

15.3.2.3 Service Manager Installation on Mac OS X
.................................................

On Mac OS X there are three installation modes `osx', `text', and
`unattended'. For more information on this topic see *Note
mem-unattended-installation::. The `text' mode installation for Mac OS
X is identical to `text' installation under Unix. For `text' mode
installation instructions see *Note mem-server-install-unix::.

Installing the MySQL Enterprise Service Manager on Mac OS X requires an
existing installation of Java. The minimum required version is 1.5.0_7.
If this version is not installed on your machine you can download it
from Apple. This version of Java requires Mac OS X version 10.4.5 as a
minimum, so you may need to upgrade your operating system in order to
install it.

For reasons of backwards compatibility, Mac OS X is usually installed
with multiple versions of Java. When installing in `osx' mode, version
1.5.0_7 must be the default version. Upon installation, Java 1.5.0_7
sets itself as the default so this is usually not a problem.

If you have changed the default you can reset it or you may install the
MySQL Enterprise Service Manager in `text' mode, setting the
environment variables to point to the correct version of Java. To
install in `text' mode, find the `installbuilder' file in the
`Contents/MacOS' directory immediately below the
`mysqlmonitor-VERSION-osx-installer.app' directory. Installing the
MySQL Enterprise Service Manager in `text' mode is identical to the
procedure described in *Note mem-server-install-unix:: with the minor
differences noted above.

To install using the GUI (`osx') installation, follow these
instructions:

  1. Double click on the MySQL Monitor installer. You should be
     presented with the Language Selection prompt. Select the language
     to use for the installer and then click `OK'.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Monitor on
     OS X: Language Selection

  2. If you have multiple Java installations on your machine, you will
     be asked to choose which Java to use with your MySQL Enterprise
     Service Manager installation. Choose the Java version you want to
     use (1.5.0 or later is required), and click `OK'.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Monitor on
     OS X: Java Selection

  3. With the installation language and Java version selected, the
     remainder of the installation sets up the installation location
     and the main configuration parameters required by MySQL Enterprise
     Service Manager. Click `Next' to contintue.

  4. Select the installation directory where you want the MySQL
     Enterprise Service Manager components installed. By default on Mac
     OS X the directory is `/Applications/mysql/enterprise/monitor'.
     You click the button next to the installation directory field to
     select a directory using the File chooser, or type the directory
     manually. Click `Next' to continue.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Monitor on
     OS X: Installation Directory

  5. Configure the options that set the network ports used by the
     Tomcat server. For more information, see *Note
     mem-server-install-generic::. Click `Next' to continue.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Monitor on
     OS X: Tomcat Server Options

  6. Configure the repository settings, setting the user name, password
     and port used to communicate with the bundled MySQL server that
     will be used to store the information and statistics for your
     installation. For more information, see *Note
     mem-server-install-generic::. Click `Next' to continue.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Monitor on
     OS X: Repository Configuration

  7. You will be provided with information and a warning about the
     configuration options and how they are stored in the
     `configuration_report.txt' file, and it's location. Take a note of
     the full path to this file in case you need to look up the
     information later. Click `Next' to continue.

  8. You should now be prompted to start the installation process.
     Click `Next' to continue.

  9. Once the installation has been completed, you will be provided
     with the information on how to uninstall MySQL Enterprise Service
     Manager.  Click `Next' to continue.

 10. To complete the installation and set up your MySQL Enterprise
     Service Manager, you will need to login to the Dashboard. You can
     do this automatically by checking the box on the final window
     before clicking `Finish'. This checkbox is selected by default. If
     you do not want to run the Dashboard at this time, uncheck the box
     and clock `Finish'.

Your installation should now be complete. To continue with the
configuration of MySQL Enterprise Service Manager, see *Note
mem-server-initial-config::.


File: manual.info,  Node: mem-server-install-unix,  Next: mem-server-starting-windows,  Prev: mem-server-install-osx,  Up: mem-install-server

15.3.2.4 Service Manager Installation on Unix
.............................................

To install the Service Manager find the file named
`mysqlmonitor-VERSION-installer.bin' (where VERSION indicates the
version number, the OS, and the architecture ). Ensure that this file is
executable by typing:

     shell> chmod +x mysqlmonitor-VERSION-installer.bin

To install to the default directory (`/opt/mysql/enterprise/monitor')
you need to be logged in as `root'. Installing as an unprivileged user
installs to the `/home/USER_NAME/mysql/enterprise/monitor/' directory.

What follows describes installation from the command line. You may
install the Service Manager graphically by running the installer from
within a windows manager. In both cases the steps are identical. You
may also install the Service Manager in `unattended' mode. This is
especially useful if you are doing multiple installations. For more
information on this topic see *Note mem-unattended-installation::.

  1. Begin installation by typing:

            shell> ./mysqlmonitor-VERSION-installer.bin

  2. First choose the language for the installation:

          Language Selection

          Please select the installation language
          [1] English
          [2] Japanese
          Please choose an option [1] :

  3. Throughout the installation process you will be asked the
     configuration questions for different options. Default values are
     shown between square brackets; to use the default press `Enter'.
     Otherwise, enter the new value and press `Enter':

     First, select the directory where you want MySQL Enterprise
     Service Manager to be installed. The default is
     `/opt/mysql/enterprise/monitor/'. Make sure that the location you
     choose has enough space to hold the installation files and the
     database information that will be created when MySQL Enterprise
     Service Manager is running.


          Please specify the directory where the MySQL Enterprise Service Manager
           will be installed.

          Installation directory [/opt/mysql/enterprise/monitor/]:

  4. Now set the Tomcat Server options. For more details on these
     parameters, see *Note mem-server-install-generic::.

          ----------------------------------------------------------------------------
          Tomcat Server Options

          Please specify the following parameters for the bundled Tomcat Server

          Tomcat Server Port [18080]:

          Tomcat Shutdown Port [18005]:

          Tomcat SSL Port [18443]:

     You will also be asked if SSL support is required. SSL support
     allows your agents and monitor to communicate with each other
     using SSL. Using SSL means that the data exchanged by the agent
     and MySQL Enterprise Service Manager are secure and can be used to
     monitor servers securely, or to monitor agents over a public
     connection.

     You can enable SSL by pressing `Y' when prompted during
     installation:

          Is SSL support required?           [y/N]:

  5. Set the repository (embedded MySQL server) configuration options.
     For more details on these parameters, see *Note
     mem-server-install-generic::.

          ----------------------------------------------------------------------------

          Repository Configuration

          Please specify the following parameters for the bundled MySQL server

          Repository Username  [service_manager]:

          Password :

          Re-enter :

          Bundled MySQL Database Port [13306]:

  6. Before the final installation process, you will provided with the
     location of the file that contains a copy of all of the settings.
     Be sure to follow the instructions and store this report in a
     secure location. There is no password recovery feature.

          ----------------------------------------------------------------------------

          Configuration Report

          Note:

          The settings you specified will be saved here:

          /opt/mysql/enterprise/monitor/configuration_report.txt

          IMPORTANT: This configuration report includes passwords stored in plain text; it
          is intended to help you install and configure your agents. We strongly advise
          you to secure or delete this text file immediately after installation.

          Press [Enter] to continue :

  7. You you will now be asked to confirm the installation process.

          Setup is now ready to begin installing MySQL Enterprise Monitor
           on your computer.

          Do you want to continue? [Y/n]: Y

          Please wait while Setup installs MySQL Enterprise Monitor
           on your computer.

     The installation process may take a few minutes to complete.  Upon
     completion you should see:

          Completed installing files

          Setup has completed installing MySQL Enterprise files on your computer

          Uninstalling the MySQL Enterprise files can be done by invoking:

          /opt/mysql/enterprise/monitor/uninstall

          To complete the installation, launch the MySQL Enterprise Dashboard and complete
          the initial setup and product activation information. Refer to the readme file
          for additional information and a list of known issues.

          Press [Enter] to continue :

  8. Finally, you will be given the opportunity to read a supplied
     `Readme' file that is supplied with the installation. The `Readme'
     contains important information about how to use and start your
     MySQL Enterprise Service Manager.

          ----------------------------------------------------------------------------

          Setup has finished installing MySQL Enterprise Monitor on your computer.

          View Readme File [Y/n]: n

     Once the `Readme' file has been displayed, or if you did not elect
     to read the file, the installation provides information about how
     to continue with your installation.

          Info: To access the MySQL Enterprise Monitor please visit the
          following page: http://localhost:18080/Auth.action

          Press [Enter] to continue :

The Enterprise Dashboard will not start up automatically if you perform
a `text' mode installation. For more information on starting and
stopping MySQL Enterprise Service Manager, see *Note
mem-server-starting-unix-osx::.


File: manual.info,  Node: mem-server-starting-windows,  Next: mem-server-starting-unix-osx,  Prev: mem-server-install-unix,  Up: mem-install-server

15.3.2.5 Starting/Stopping the MySQL Enterprise Monitor Service on Windows
..........................................................................

You can choose to start up the MySQL Enterprise Service Manager on
installation.  The installed services are called:

   * MySQL Enterprise Tomcat

   * MySQL Enterprise MySQL

You can stop or start the services from the Microsoft Management
Console Services window. Look for the `MySQL Enterprise Tomcat' and the
`MySQL Enterprise MySQL' entries.

*Note*:

On Windows Vista, starting these services requires administrative
privileges -- you must be logged in as an administrator. To start or
stop a service right click it and choose the `Run as Administrator'
menu option.  The same restriction applies to using the menu options
discussed in the following and to starting the services from the command
line. To open an administrator `cmd' window right click the `cmd' icon
and choose the `Run as Administrator' menu option.

To start or stop a service, right click it and choose from the options
in the pop-up menu.

There is also a menu entry for starting and stopping the services.
Navigate to the `Program', `MySQL', `MySQL Enterprise Monitor',
`Services' entry to stop or start the services.

You can also stop or start a service from the command line. To start
the Tomcat service type:

     shell> sc start MySQLEnterpriseTomcat

or:

     shell> net start MySQLEnterpriseTomcat

To stop this service type:

     shell> sc stop MySQLEnterpriseTomcat

or:

     shell> net stop MySQLEnterpriseTomcat

In similar fashion, you may stop or start the MySQL server from the
command line. The service name is `MySQLEnterpriseMySQL'.

You may also start, stop, and restart a specific service or both
services using the `mysqlmonitorctl.bat' file.  To execute this file,
go to the command line and navigate to the `C:\Program
Files\MySQL\Enterprise\Monitor' directory. Typing mysqlmonitorctl.bat
help produces the following output:

     usage: mysqlmonitorctl.bat help
            mysqlmonitorctl.bat (start|stop|restart|install|uninstall)
            mysqlmonitorctl.bat (start|stop|restart) tomcat
            mysqlmonitorctl.bat (start|stop|restart) mysql

     help       - this screen
     start      - start the service(s)
     stop       - stop the service(s)
     restart    - restart or start the service(s)
     install    - install the service(s)
     uninstall  - uninstall the service(s)

To stop a specific service, pass the argument `tomcat' or `mysql' in
addition to the status change argument. If you wish to change the
status of both services, do not specify a service name. You may also
uninstall the services using this batch file.

Configuration of the dashboard begins immediately after the Service
Manager is installed. To continue a Windows installation skip the next
section and go to *Note mem-server-initial-config::.


File: manual.info,  Node: mem-server-starting-unix-osx,  Next: mem-server-initial-config,  Prev: mem-server-starting-windows,  Up: mem-install-server

15.3.2.6 Starting/Stopping the MySQL Enterprise Monitor Service on Unix and Mac OS X
....................................................................................

The services incorporated into the MySQL Enterprise Service Manager are:

   * The MySQL Server

   * The Apache/Tomcat Server

Should you need to stop, start, or restart the MySQL Enterprise Service
Manager call the `mysqlmonitorctl.sh' file located in the
`/opt/mysql/enterprise/monitor/' directory on Unix or the
`/Applications/mysql/enterprise/monitor/' on Mac OS X. To see all the
available options navigate to the appropriate directory and type:

     shell> /opt/mysql/enterprise/monitor/mysqlmonitorctl.sh help

Executing this script produces the following output:

     usage: ./mysqlmonitorctl.sh help
     ./mysqlmonitorctl.sh (start|stop|status|restart)
     ./mysqlmonitorctl.sh (start|stop|status|restart) mysql
     ./mysqlmonitorctl.sh (start|stop|status|restart) tomcat

     help       - this screen
     start      - start the service(s)
     stop       - stop  the service(s)
     restart    - restart or start the service(s)
     status     - report the status of the service

Using this script you can stop, start, or restart all the Service
Manager components. To do this make a call to `mysqlmonitorctl.sh
start' from your start-up script.

To start the service:

     shell> ./mysqlmonitorctl.sh start
     ./mysqlmonitorctl.sh : mysql  started
     nohup: redirecting stderr to stdout
     Starting mysqld daemon with databases from /opt/mysql/enterprise/monitor/mysql/data/
     Using CATALINA_BASE:   /opt/mysql/enterprise/monitor/apache-tomcat
     Using CATALINA_HOME:   /opt/mysql/enterprise/monitor/apache-tomcat
     Using CATALINA_TMPDIR: /opt/mysql/enterprise/monitor/apache-tomcat/temp
     Using JRE_HOME:       /opt/mysql/enterprise/monitor/java

If you try to start the service and it is already running, you will be
warned that the services are already running:

     shell> ./mysqlmonitorctl.sh start
     ./mysqlmonitorctl.sh : mysql  (pid 18403) already running
     ./mysqlmonitorctl.sh : tomcat  (pid 18480) already running

To stop the service:

     shell> ./mysqlmonitorctl.sh stop
     Using CATALINA_BASE:   /Applications/mysql/enterprise/monitor/apache-tomcat
     Using CATALINA_HOME:   /Applications/mysql/enterprise/monitor/apache-tomcat
     Using CATALINA_TMPDIR: /Applications/mysql/enterprise/monitor/apache-tomcat/temp
     Using JRE_HOME:       /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home
     Stopping tomcat service .. [ OK ]
     STOPPING server from pid file /Applications/mysql/enterprise/monitor/mysql/data/mysqld.pid
     090209 15:37:09  mysqld ended

The `restart' command is equivalent to executing a `stop' and then
`start' operation.

This script can also be used to check the status of the Tomcat web
server or the MySQL repository.

     shell> ./mysqlmonitorctl.sh status
     MySQL Network MySQL is running
     MySQL Network Tomcat is running

Configuration of the dashboard begins immediately after the MySQL
Enterprise Service Manager is installed.


File: manual.info,  Node: mem-server-initial-config,  Prev: mem-server-starting-unix-osx,  Up: mem-install-server

15.3.2.7 MySQL Enterprise Service Manager Configuration Settings and Advisor Installation
.........................................................................................

* Menu:

* mem-first-login-dashboard::    Initial Dashboard Log-in
* mem-localization::             Setting the Timezone and Locale
* mem-advisor-installation-after-login::  Installing Advisors After Initial Log-in
* mem-upgrading-updating-advisors::  Upgrading and Updating Advisors
* mem-outgoing-email-settings::  Outgoing Email Settings

The Enterprise Dashboard is the web-based interface to the Service
Manager so the procedure for starting the dashboard is identical for
all platforms. From the dashboard you can configure the settings
necessary for receiving updates from MySQL Enterprise and for the
initial installation of the Advisors.

If you installed the Service Manager using a graphical interface, you
have the option of launching the dashboard on the final installation
screen (as long as the `Launch MySQL Enterprise Monitor Now' checkbox
is checked).

Otherwise, you can view the dashboard by typing
`http://localhost:18080/Auth.action' into the address bar of your web
browser. If you are unsure of the host name and port to use, check the
`configuration_report.txt' file.

Under Windows it is also possible to open the dashboard by choosing the
`MySQL' menu item and finding the `MySQL Enterprise Monitor' entry.
Under this entry choose `Start Service Manager'.


File: manual.info,  Node: mem-first-login-dashboard,  Next: mem-localization,  Prev: mem-server-initial-config,  Up: mem-server-initial-config

15.3.2.8 Initial Dashboard Log-in
.................................

If this is the first time that you have attempted to log in to the
dashboard you should see a screen similar to the following:

FIGURE GOES HERE: MySQL Enterprise Monitor: Initial dashboard log-in

Use this screen to perform the following tasks:

   * Install the Advisors

   * Set up your MySQL Enterprise credentials

   * Create a user name and password for the dashboard administrator

   * Create a user name and password for the Monitor Agent

If you have been provided with a `MySQL Enterprise Product Key' and an
Advisors file click the `Browse' button and locate these files. The
advisor file bears the name, `AdvisorScript-VERSION.jar' and the
product key, `SUBSCRIPTION-LEVEL_DATE.xml'.  If you do not allow
Internet access from the dashboard you must install the advisors in
this way. It is strongly recommended that you install the Advisors at
this point, but you may do so later. For instructions on doing this see,
*Note mem-advisor-installation-after-login::. If the product key that
you provide is invalid a notification appears and you will be unable to
import the advisors.

*Note*:

If you are activating the MySQL Enterprise Monitor using a product key
do_not_ enter your MySQL credentials; entering both produces an error
message.

If you have Internet access from the dashboard, activate MySQL
Enterprise Monitor by supplying your MySQL Enterprise credentials. Enter
your email address as the `MySQL Enterprise Login' and enter and
confirm your MySQL Enterprise password. If you specify incorrect
credentials, you receive the error message, `Unable to connect to verify
credentials.'

In the `Create Administrator' section of this screen, enter credentials
for the dashboard administrator. This creates the `root user' described
in *Note mem-users-created-first-login::. Make note of the user name
and password as these credentials are required for any future login.

In the `Configure Agent Credentials' section of this screen enter the
credentials for the agent. This is the `agent user' also described in
*Note mem-users-created-first-login::. The agent needs to log in in
order to report its findings. Make note of the agent's credentials;
this information is required when installing the agent.

When all the settings have been specified, click the `complete setup'
button. If you log in successfully you should see a message displaying
the number of graphs and advisors that have been imported. This number
varies depending upon your subscription level.

If importation of the advisor files fails, you will see the message:

     Unable to import Advisor Jar. You may download the jar
     manually from the Enterprise Portal and import it from the 'Check For Updates' page.

In this case you may download the advisor file from the Enterprise
website and install it as described in *Note
mem-advisor-installation-after-login::.


File: manual.info,  Node: mem-localization,  Next: mem-advisor-installation-after-login,  Prev: mem-first-login-dashboard,  Up: mem-server-initial-config

15.3.2.9 Setting the Timezone and Locale
........................................

If this is the first time that you have launched the dashboard you are
asked to set your time zone and locale. Choose the appropriate values
from the drop-down list boxes. Setting the time zone ensures that you
have an accurate time reference for any notifications from the MySQL
Enterprise Advisors.

*Warning*:

It is especially important that the time zone be set correctly as this
may also affect the way the graphs display. For this reason, also
ensure that the time reported by the operating system is correct. To
change the time zone or locale see *Note mem-user-preferences::.

The locale chosen determines the user's default language when logging
in to the Dashboard. Note that this will override the default browser
settings whenever this specific user logs in.

After specifying your time zone and locale, the dashboard opens on the
`Monitor' page. For a detailed examination of the `Monitor' Screen see,
*Note mem-dashboard::.


File: manual.info,  Node: mem-advisor-installation-after-login,  Next: mem-upgrading-updating-advisors,  Prev: mem-localization,  Up: mem-server-initial-config

15.3.2.10 Installing Advisors After Initial Log-in
..................................................

The Advisors interpret the data sent by the Monitor Agents and display
the results in the dashboard. A minimal set of Advisors are
preinstalled with the Service Manager. To obtain the full set of
Advisors and get the most value from the MySQL Enterprise Monitor, you
must download Advisors from MySQL Enterprise.

If you did not install the Advisors when you first logged in to the
MySQL Enterprise Dashboard, open the dashboard, find the `Advisors'
tab, and choose the `Check for Updates' link. Doing this downloads the
latest version of the Advisors from the MySQL Enterprise web site. In
order to install the advisors in this fashion you must specify your
MySQL Enterprise credentials. Find instructions for doing this in *Note
mem-global-settings::.

If you do not allow Internet access from the dashboard, you must
install the Advisors from a local file. To do this you need an advisor
file bearing the name, `AdvisorScript-VERSION.jar'.  If you don't
already have this file, you can find it on the MySQL Enterprise
downloads page. Download the Advisors file to a location that is
accessible from the dashboard. Use the `Browse' button to find the
Advisors file and then choose `import' to load the advisors.


File: manual.info,  Node: mem-upgrading-updating-advisors,  Next: mem-outgoing-email-settings,  Prev: mem-advisor-installation-after-login,  Up: mem-server-initial-config

15.3.2.11 Upgrading and Updating Advisors
.........................................

The process for upgrading advisors is exactly the same as the initial
installation. Advisors are updated by choosing the `update' button on
the `Check for Updates' page. If you do not have Internet access from
the dashboard you can import the Advisors from a local file as
described in *Note mem-advisor-installation-after-login::.

*Note*:

You may choose to upgrade your MySQL Enterprise Monitor subscription
level at any time.


File: manual.info,  Node: mem-outgoing-email-settings,  Prev: mem-upgrading-updating-advisors,  Up: mem-server-initial-config

15.3.2.12 Outgoing Email Settings
.................................

Alert notification via email is a key component of the MySQL Enterprise
Monitor Advisor solution. For this reason you may want to immediately
configure an SMTP account for at least one recipient.

To do this choose the `Settings' tab and go to the `Global Settings'
screen by clicking the appropriate link. Here you can configure the
email settings.  These settings apply to the currently logged-in user.

Find the `Outgoing Email Settings' on the left of this page.

FIGURE GOES HERE: MySQL Enterprise Monitor: Outgoing email settings

Ensure that the `Enable Email Notifications' checkbox is checked and
enter information as appropriate.

The default value for the SMTP port is `25'. If your mail server runs
on a different port simply specify it, separating it from the server
name using a colon. For example, if your mail server runs on port 587
enter `EMAIL.MYSERVER.COM:587' into the `SMTP Server' text box.

*Note*:

An email server must be available for sending email alerts.

The SMTP client uses Transport Layer Security (TLS) if the SMTP server
supports it.

If your SMTP server incorrectly indicates that it supports TLS, check
the `Disable JavaMail TLS/SSL' check box.

The email settings page is dealt with in more detail in *Note
mem-dashboard-settings::.


File: manual.info,  Node: mem-install-agent,  Next: mem-unattended-installation,  Prev: mem-install-server,  Up: mem-install

15.3.3 Monitor Agent Installation
---------------------------------

* Menu:

* mem-agent-rights::             Creating a MySQL User Account for the Monitor Agent
* mem-install-agent-windows::    Installing the Agent on Microsoft Windows
* mem-install-agent-osx::        Installing the Agent on Mac OS X
* mem-install-agent-unix::       Installing the Monitor Agent on Unix
* agent-starting-stopping::      Starting/Stopping the MySQL Enterprise Monitor Agent
* mem-advanced-agent-configuration::  Advanced Agent Configuration
* mem-troubleshooting-agent-start::  Troubleshooting the Agent

A MySQL Enterprise Monitor Agent monitors a MySQL server and sends data
to the Advisors. These data are interpreted and displayed in the
dashboard.  The Monitor Agent is installed on all platforms using the
steps described in the next section.

*Warning*:

The MySQL Enterprise Service Manager version 2.0 or higher requires
agents with a version number of 2.0 or higher.


File: manual.info,  Node: mem-agent-rights,  Next: mem-install-agent-windows,  Prev: mem-install-agent,  Up: mem-install-agent

15.3.3.1 Creating a MySQL User Account for the Monitor Agent
............................................................

Before setting up an agent to monitor a MySQL server you need to ensure
that there is a user account for the agent on that server.

The privileges required for this user account vary depending on the
information you wish to gather using the MySQL Enterprise Monitor
Agent. The following privileges allow the Monitor Agent to perform its
assigned duties without limitation:

   * `SHOW DATABASES': Allows the MySQL Enterprise Monitor Agent to
     gather inventory about the monitored MySQL server.

   * `REPLICATION CLIENT': Allows the MySQL Enterprise Monitor Agent to
     gather Replication master/slave status data.  This privilege is
     only needed if the MySQL Replication Advisor Rules are employed.

   * `SELECT': Allows the MySQL Enterprise Monitor Agent to collect
     statistics for table objects.

   * `SUPER': Allows the MySQL Enterprise Monitor Agent to execute
     `SHOW ENGINE INNODB STATUS' in order to collect data about InnoDB
     tables.

   * `PROCESS': When monitoring a MySQL server running MySQL 5.1.24 or
     above with `InnoDB', the `PROCESS' privilege is required to
     execute `SHOW ENGINE INNODB STATUS'.

   * `INSERT': Required to create the UUID required by the agent.

   * `CREATE': Allows the MySQL Enterprise Monitor Agent to create
     tables. During discovery, the agent creates the table `inventory'
     within the `mysql' database that is used to the UUID for the
     server. Without this table, the agent cannot determine the UUID of
     the server and therefore use this when sending information to
     MySQL Enterprise Service Manager.

For example, the following `GRANT' statement will give the agent the
required `SELECT', `REPLICATION CLIENT', `SHOW DATABASES' and `SUPER'
rights:

     GRANT SELECT, REPLICATION CLIENT, SHOW DATABASES, SUPER, PROCESS
       ON *.*
       TO  'MYSQLUSER'@'LOCALHOST'
       IDENTIFIED BY 'AGENT_PASSWORD';

For security reasons, you may wish to limit the `CREATE' and `INSERT'
privileges to the agent so that it can only create tables within the
`mysql' database:

     GRANT CREATE, INSERT
       ON mysql.*
       TO  'MYSQLUSER'@'LOCALHOST'
       IDENTIFIED BY 'AGENT_PASSWORD';

To enable replication discovery to work, you should also grant the
`SELECT' privilege on the `mysql.inventory' table for each user with
replication privileges on the corresponding replication master.  This
is required to let the MySQL Enterprise Monitor Agent read the
replication master UUID. For example:

     GRANT SELECT
       ON mysql.inventory
       TO  'REPLICATIONUSER'@'%'
       IDENTIFIED BY 'REPLICATION_PASSWORD';

If the agent is unable to access the information from the table then a
warning containing this information will be written to the agent log.

*Note*:

You may want to disable logging for the grant statement to prevent the
grant information being replicated to the slaves. If this is the case,
execute the statement `SET SQL_LOG_BIN=0' before you execute the above
`GRANT' statement.

In a typical configuration, the agent runs on the same machine as the
MySQL server it is monitoring so the host name will be LOCALHOST.
However, this will change if the agent is running on a machine other
than the one that hosts the monitored MySQL server. In this case, change
LOCALHOST to the appropriate value. For more information about remote
monitoring see *Note mem-install-agent-remote::.


File: manual.info,  Node: mem-install-agent-windows,  Next: mem-install-agent-osx,  Prev: mem-agent-rights,  Up: mem-install-agent

15.3.3.2 Installing the Agent on Microsoft Windows
..................................................

To install the MySQL Enterprise Monitor Agent on Windows, double-click
the `mysqlmonitoragent-VERSION-windows-installer.exe' (where VERSION
indicates the three-part version number) installer.

*Note*:

In order to install the agent as a Windows service, you must do the
installation as a privileged user.

On Windows Vista, if user account control is on, an operating system
dialog box requests confirmation of the installation.

You may also install the Monitor Agent in `unattended' mode. This is
especially useful if you are doing multiple installations. For more
information on this topic see, *Note mem-unattended-installation::.

  1. First, select the language for the MySQL Enterprise Monitor Agent
     installation. Click `OK' to continue installation.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent on
     Windows: Language Selection

  2. Click `Next' to start the installation process.

  3. Select the installation directory. The default installation
     directory is `C:\Program Files\MySQL\Enterprise\Agent'. Select the
     installation directory, or type the new directory location.  Click
     `Next' to continue the installation process.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent on
     Windows: Installation Directory

  4. You need to specify the information about the MySQL server that
     you want to monitor. You must enter the IP address or host name of
     the host you want to monitor, and the port, user name and password
     that you will use to connect to the MySQL server. If you want to
     confirm that the MySQL server is currently reachable using the
     information, ensure that the `Validate MySQL host name or IP
     address' checkbox is selected.

     *Note*:

     Currently, on Windows, the service agent only includes support for
     connecting to the server to be monitored via TCP/IP, so if the
     server has been started with `--skip-networking' it cannot be
     monitored.  If the MySQL server to be monitored has been started
     using the command option `--bind-address' then the server will
     only listen for connections on the IP address specified, that is,
     the IP address of the MySQL server. If the service agent has been
     started using TCP/IP networking and the default address of
     127.0.0.1 it will not be able to connect to the server to be
     monitored. Also, if `localhost' is specified as the host name
     during agent configuration, a connection will not be established,
     as the server will be listening for connections on the address
     specified with the `--bind-address' option, not 127.0.0.1.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent on
     Windows: Monitored Database Information

     Click `Next' to continue the installation.

  5. If you want to use Query Analyzer, then you need to enable the
     MySQL Enterprise Monitor Agent Proxy. The Proxy is enabled by
     default. If you disable the Proxy during installation, you will
     need to enable it later before you are able to use Query Analysis.
     For more information on Query Analyzer, see *Note
     mem-query-analysis::.

     When Proxy is enabled, MySQL Enterprise Monitor Agent listens on a
     network port for client applications, and forwards the connections
     to the backend MySQL server. You can change the port number that
     MySQL Enterprise Monitor Agent listens for connections The default
     port is 4040.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent on
     Windows: Query Analyzer Configuration

  6. The MySQL Enterprise Service Manager that you want to use must be
     configured during installation. The host name, port and agent
     authentication information must be entered. If you have already
     installed MySQL Enterprise Service Manager then you can locate the
     information in the installation report file created during
     installation. Enter the required information and then click `Next'
     to continue.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent on
     Windows: MySQL Enterprise Service Manager Options

  7. You will be provided with a Configuration Report containing the
     information that you have entered during the installation.  Check
     the information provided in the report. If you see a problem, use
     `Back' to go back to the configuration screen and change the
     information. If the information is correct, click `Next' to
     continue.

  8. You are given a final opportunity to change the installation
     parameters. Click `Next' to start the installation process.

  9. Once the agent has been installed, you will get a confirmation
     message. Click `Next' to finalize the installation.

 10. You can start the MySQL Enterprise Monitor Agent automatically now
     the installation has been completed. To allow the agent to be
     started, leave the checkbox selected. To start the agent
     separately, uncheck the checkbox. Click `Finish' to exit the
     installation.

Once the Monitor Agent is installed, it needs to be started. For
information on how to start and stop the Agent, see *Note
mem-starting-agent-windows::.


File: manual.info,  Node: mem-install-agent-osx,  Next: mem-install-agent-unix,  Prev: mem-install-agent-windows,  Up: mem-install-agent

15.3.3.3 Installing the Agent on Mac OS X
.........................................

To install the MySQL Enterprise Monitor Agent on Mac OS X, decompress
the `mysqlmonitoragent-VERSION-installer.app.zip' and then run the
`mysqlenterpriseagent-VERSION-installer' application.

  1. First, select the language for the MySQL Enterprise Monitor Agent
     installation. Click `OK' to continue installation.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent on
     Mac OS X: Language Selection

  2. Click `Next' to start the installation process.

  3. Select the installation directory. The default installation
     directory is `C:\Program Files\MySQL\Enterprise\Agent'. Select the
     installation directory, or type the new directory location.

     You also need to select the method that the agent will use to
     communicate with the MySQL server. You can choose either to use a
     TCP/IP (network) connection, or a Socket (local) connection.
     Choose the connection method, and click `Next'.

     *Note*:

     The service agent always associates `localhost' with the TCP/IP
     address 127.0.0.1, not the MySQL socket. This is in contrast to
     the MySQL Command Line Tool, which connects via the MySQL socket
     by default on Unix, if the hostname `localhost' is specified.  If
     the MySQL server you wish to monitor has been started with the
     `--skip-networking' command option then you will not be able to
     connect to it via TCP/IP, as the server will not listen for TCP/IP
     connections. In this case the service agent will need to be
     configured to use the MySQL socket. This can be done during
     installation by selecting `socket' rather than `TCP/IP' and then
     specifying the MySQL socket name. This can also be configured
     after installation by editing the `agent-instance.ini'
     configuration file, for further information on this refer to *Note
     mem-cfg-agent-ini::.  If the MySQL server to be monitored has been
     started using the command option `--bind-address' then the server
     will only listen for connections on the IP address specified, that
     is, the IP address of the MySQL server. If the service agent has
     been started using TCP/IP networking and the default address of
     127.0.0.1 it will not be able to connect to the server to be
     monitored. Also, if `localhost' is specified as the host name
     during agent configuration, a connection will not be established,
     as the server will be listening for connections on the address
     specified with the `--bind-address' option, not 127.0.0.1.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent on
     Mac OS X: Installation Directory

  4. You need to specify the information about the MySQL server that
     you want to monitor. The configuration information you enter will
     depend on the connection method selected in the previous screen.

        * If you chose TCP/IP as the connection method, you must enter
          the IP address or host name of the host you want to monitor,
          and the port, user name and password that you will use to
          connect to the MySQL server. If you want to confirm that the
          MySQL server is currently reachable using the information,
          ensure that the `Validate MySQL host name or IP address'
          checkbox is selected.

          FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent
          on Mac OS X: Monitored Database Information

        * If you chose Socket as the connection method, you must enter
          the full path name to the Unix socket created by your MySQL
          server, and the user name and password that will be used to
          authenticate with the server. Typical values include
          `/tmp/mysql.sock' and `/var/mysql/mysql.sock'.

          FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent
          on Mac OS X: Monitored Database Information

     Click `Next' to continue the installation.

  5. If you want to use Query Analyzer, then you need to enable the
     MySQL Enterprise Monitor Agent Proxy. The Proxy is enabled by
     default. If you disable the Proxy during installation, you will
     need to enable it later before you are able to use Query Analysis.
     For more information on Query Analyzer, see *Note
     mem-query-analysis::.

     When Proxy is enabled, MySQL Enterprise Monitor Agent listens on a
     network port for client applications, and forwards the connections
     to the backend MySQL server. You can change the port number that
     MySQL Enterprise Monitor Agent listens for connections The default
     port is 4040.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent on
     Mac OS X: Query Analyzer Configuration

  6. The MySQL Enterprise Service Manager that you want to use must be
     configured during installation. The host name, port and agent
     authentication information must be entered. If you have already
     installed MySQL Enterprise Service Manager then you can locate the
     information in the installation report file created during
     installation. Enter the required information and then click `Next'
     to continue.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Installing Agent on
     Mac OS X: MySQL Enterprise Service Manager Options

  7. You will be provided with a Configuration Report containing the
     information that you have entered during the installation.  Check
     the information provided in the report. If you see a problem, use
     `Back' to go back to the configuration screen and change the
     information. If the information is correct, click `Next' to
     continue.

  8. You are given a final opportunity to change the installation
     parameters. Click `Next' to start the installation process.

  9. Once the agent has been installed, you will get a confirmation
     message. Click `Next' to finalize the installation.

 10. You can start the MySQL Enterprise Monitor Agent automatically now
     the installation has been completed. To allow the agent to be
     started, leave the checkbox selected. To start the agent
     separately, uncheck the checkbox. Click `Finish' to exit the
     installation.

Once the Monitor Agent is installed, it needs to be started. For
information on how to start and stop the Agent, see *Note
mem-starting-agent-osx::.


File: manual.info,  Node: mem-install-agent-unix,  Next: agent-starting-stopping,  Prev: mem-install-agent-osx,  Up: mem-install-agent

15.3.3.4 Installing the Monitor Agent on Unix
.............................................

As a prerequisite for installing the MySQL Enterprise Monitor Agent on
Linux systems you must have the Linux Standards Base (LSB)
initialization functions installed.

To install the agent navigate to the directory that contains the file,
`mysqlmonitoragent-VERSION-installer.bin' (where VERSION indicates the
three-part version number, the OS, and the architecture). Ensure that
this file is executable by typing:

     shell> chmod +x mysqlmonitoragent-VERSION-installer.bin

To install to the default directory (`/opt/mysql/enterprise/agent') you
need to be logged in as `root'. Installing as an unprivileged user
installs to the `/home/USER_NAME/mysql/enterprise/agent' directory.

*Note*:

If you install the agent as an unprivileged user, it will not
automatically start up on rebooting.

What follows describes installation from the command line. You may
install the Monitor Agent graphically by running the installer from
within a windows manager. In both cases the steps are identical. You
may also install the Monitor Agent in `unattended' mode. This is
especially useful if you are doing multiple installations. For more
information on this topic see *Note mem-unattended-installation::.

Begin installation from the command line by typing:

     shell> ./mysqlmonitoragent-VERSION-installer.bin --mode text

The various options are shown in what follows. Default values are
indicated by square brackets; to select them press `Enter'. Otherwise
enter a value of your choosing.

  1. First, you must select the Language you want to use during the
     installation process:

          Language Selection

          Please select the installation language
          [1] English
          [2] Japanese
          Please choose an option [1] :

  2. Next, specify the directory where you want the agent installed:

          ----------------------------------------------------------------------------
          Welcome to the MySQL Enterprise Monitor Agent Setup Wizard.

          ----------------------------------------------------------------------------
          Please specify the directory where MySQL Enterprise Monitor Agent will be installed

          Installation directory [/opt/mysql/enterprise/agent]:

  3. Specify the MySQL server that you want to monitor. First, you must
     specify whether you want to use a TCP/IP or socket-based
     connection to communicate with the MySQL Server:

          How will the agent connect to the database it is monitoring?

          [1] TCP/IP
          [2] Socket
          Please choose an option [1] :

     If you select TCP/IP, then you will be asked to enter the TCP/IP
     address and port number:

          ----------------------------------------------------------------------------
          Monitored Database Information

          IMPORTANT: The agent user account specified below requires special MySQL privileges.

          Visit the following URL for more information:
          https://enterprise.mysql.com/docs/monitor/2.0/en/mem-install.html#mem-agent-rights

          MySQL hostname or IP address [127.0.0.1]:

          Validate MySQL hostname or IP address [Y/n]:

          MySQL Port [3306]:

     If you select Socket, then you will be asked to provide the path
     name to the MySQL socket. Typical values are `/tmp/mysql.sock',
     `/var/lib/mysql.sock', or `/var/run/mysql.sock'.

          ----------------------------------------------------------------------------
          Monitored Database Information

          IMPORTANT: The agent user account specified below requires special MySQL privileges.

          Visit the following URL for more information:
          https://enterprise.mysql.com/docs/monitor/2.0/en/mem-install.html#mem-agent-rights

          MySQL Socket []:

     *Note*:

     The service agent always associates `localhost' with the TCP/IP
     address 127.0.0.1, not the MySQL socket. This is in contrast to
     the MySQL Command Line Tool, which connects via the MySQL socket
     by default on Unix, if the hostname `localhost' is specified.  If
     the MySQL server you wish to monitor has been started with the
     `--skip-networking' command option then you will not be able to
     connect to it via TCP/IP, as the server will not listen for TCP/IP
     connections. In this case the service agent will need to be
     configured to use the MySQL socket. This can be done during
     installation by selecting `socket' rather than `TCP/IP' and then
     specifying the MySQL socket name. This can also be configured
     after installation by editing the `agent-instance.ini'
     configuration file, for further information on this refer to *Note
     mem-cfg-agent-ini::.  If the MySQL server to be monitored has been
     started using the command option `--bind-address' then the server
     will only listen for connections on the IP address specified, that
     is, the IP address of the MySQL server. If the service agent has
     been started using TCP/IP networking and the default address of
     127.0.0.1 it will not be able to connect to the server to be
     monitored. Also, if `localhost' is specified as the host name
     during agent configuration, a connection will not be established,
     as the server will be listening for connections on the address
     specified with the `--bind-address' option, not 127.0.0.1.

  4. Specify the user credentials for the MySQL server that you want to
     monitor:


          MySQL Username []: SERVICE_AGENT

          MySQL Password :

          Re-enter :

  5. Select whether you want to enable Query Analyzer. If you disable
     the Query Analyzer during installation, you will need to manually
     edit the configuration file to re-enable the Query Analyzer
     functionality. If you enable Query Analysis (Proxy), you must
     specify the port on which the agent will listen for queries.

          ----------------------------------------------------------------------------
          Query Analyzer Configuration

          MySQL Proxy enables query monitoring and analysis by listening on a specified port for client connections that are then passed through to a backend MySQL database server. It is not needed for basic monitoring functionality.

          Click here for more information.
           [Y/n]:

          Enable Proxy (recommended) [Y/n]:

          Proxy Port [4040]:

          Backend Host: 127.0.0.1   (cannot be changed)

          Backend Port: 3306   (cannot be changed)

     For more information on enabling Query Analyzer if you disabled it
     during installation, see *Note mem-query-analysis::.

  6. Enter the details of the MySQL Enterprise Service Manager that you
     want to use with this agent. The configuration information
     required is available within the installation report generated
     when you installed MySQL Enterprise Service Manager


          ----------------------------------------------------------------------------

          MySQL Enterprise Monitor Options

          Hostname or IP address []: 192.168.0.197

          Tomcat Server Port [18080]:

          Tomcat SSL Port [18443]:

     The agent and MySQL Enterprise Service Manager support using SSL
     for communication. If you want to enable SSL communication between
     the agent and the MySQL Enterprise Service Manager, you must reply
     `Y' to the following question.


          Use SSL? [y/N]:

          Agent Username [agent]:

          Agent Password :

          Re-enter :

          ----------------------------------------------------------------------------

  7. Before installation starts, you will be provided with a summary of
     the installation settings that you have specified:

          Here are the settings you specified:

          Installation directory: /opt/mysql/enterprise/agent

          Monitored MySQL Database:
          -------------------------
          Hostname or IP address: 127.0.0.1
          Port: 3306
          MySQL username: MYSQL_USER
          MySQL password: PASSWORD

          Query Analyzer Configuration
          -------------------------
          Proxy Enabled: yes
          Proxy Port: 4040

          MySQL Enterprise Manager:
          ------------------------------

          Hostname or IP address: 192.168.0.197

          Tomcat Server Port: 18080
          Tomcat SSL Port: 18443
          Use SSL: 0
          Agent username: AGENT

          Press [Enter] to continue :

          ----------------------------------------------------------------------------

          Setup is now ready to begin installing MySQL Enterprise Monitor Agent on your computer.

          Do you want to continue? [Y/n]: y

  8. The installer will copy the necessary files and create the
     configuration file required to run the agent:

          ----------------------------------------------------------------------------
          Please wait while Setup installs MySQL Enterprise Monitor Agent on your computer.

           Installing
           0% ______________ 50% ______________ 100%
           #########################################

          ----------------------------------------------------------------------------
          Info to start MySQL Agent

          The MySQL agent was successfully installed. To start the MySQL Agent please
          invoke:
          /opt/mysql/enterprise/agent/etc/init.d/mysql-monitor-agent start
          Press [Enter] to continue :

          ----------------------------------------------------------------------------
          Setup has finished installing MySQL Enterprise Monitor Agent on your computer.

  9. Finally, you can read the supplied `README' file when prompted.
     The file is provided within the `share/doc/README_en.txt' file
     within the agent installation directory if you would like to read
     this file separately.

For information on starting the agent, see *Note
mem-starting-agent-unix::.


File: manual.info,  Node: agent-starting-stopping,  Next: mem-advanced-agent-configuration,  Prev: mem-install-agent-unix,  Up: mem-install-agent

15.3.3.5 Starting/Stopping the MySQL Enterprise Monitor Agent
.............................................................

* Menu:

* mem-starting-agent-windows::   Starting/Stopping the Agent on Windows
* mem-starting-agent-osx::       Starting/Stopping the Agent on Mac OS X
* mem-starting-agent-unix::      Starting/Stopping the Agent on Unix

The MySQL Enterprise Monitor Agent can be started and stopped at any
time. When not running, information about the current status of your
server will not be available, and MySQL Enterprise Service Manager will
provide a warning if an agent and the MySQL server that it monitors is
unavailable.

*Warning*:

If you are using Query Analyzer, then turning off the agent will
prevent your applications from communicating with the MySQL server. See
*Note mem-query-analysis::.


File: manual.info,  Node: mem-starting-agent-windows,  Next: mem-starting-agent-osx,  Prev: agent-starting-stopping,  Up: agent-starting-stopping

15.3.3.6 Starting/Stopping the Agent on Windows
...............................................

You have the option of starting the Monitor Agent from the final
installation screen. Otherwise you can do this by going to the `Start
Menu' and under `Programs' find `MySQL' and then the `MySQL Enterprise
Monitor Agent' entry. Simply select the `Start MySQL Enterprise Monitor
Agent' option.

*Note*:

On Windows Vista, starting the agent requires administrative privileges
-- you must be logged in as an administrator.  To start or stop the
agent right click the menu item and choose the `Run as Administrator'
menu option. The same restriction applies to starting the agent from
the command line. To open an administrator `cmd' window right-click the
`cmd' icon and choose the `Run as Administrator' menu option.

*Warning*:

To report its findings, the agent needs to be able to connect to the
dashboard through the port specified during installation. The default
value for this port is `18080'; ensure that this port is not blocked.
If you need help troubleshooting the agent installation see, *Note
mem-troubleshooting-agent-start::.

Alternately, you can start the agent from the command line by entering:

     shell> sc start MySQLEnterpriseMonitorAgent

or:

     shell> net start MySQLEnterpriseMonitorAgent

You can also start the agent by issuing the command, `agentctl.bat
start'. Stop the agent by passing the argument, `stop'. This batch file
is found in the `Agent' directory.

For confirmation that the service is running you can open the Microsoft
Management Console Services window. To do this go to the Control Panel,
find `Administrative Tools' and click on the link to `Services'. Locate
the service named `MySQL Enterprise Monitor Agent' and look under the
`Status' column.

You may also start the agent from this window rather than from the
`Start' menu or the command line. Simply right click `MySQL Enterprise
Monitor Agent' and choose `Start' from the pop-up menu. Starting the
agent from this window opens an error dialog box if the agent cannot
connect to the MySQL server it is monitoring. No error is displayed if
the agent is unable to connect to the MySQL Enterprise Service Manager.

The pop-up menu for starting the agent also offers the option of
stopping the agent. To stop the agent from the command line you only
need type:

     shell> sc stop MySQLEnterpriseMonitorAgent

or:

     shell> net stop MySQLEnterpriseMonitorAgent

*Note*:

`MySQLEnterpriseMonitorAgent' is the default name of the Monitor Agent
service. If you have added an additional agent as described in *Note
mem-cfg-agent-ini::, replace `MySQLEnterpriseMonitorAgent' with the
appropriate agent name.


File: manual.info,  Node: mem-starting-agent-osx,  Next: mem-starting-agent-unix,  Prev: mem-starting-agent-windows,  Up: agent-starting-stopping

15.3.3.7 Starting/Stopping the Agent on Mac OS X
................................................

The script to start the agent on Mac OS X is located in the
`/Applications/mysql/enterprise/agent/etc/init.d' directory. To start
the agent navigate to this directory and at the command line type:

     shell> ./mysql-monitor-agent start

To stop the agent, use the `stop' command:

     shell> ./mysql-monitor-agent stop

If the agent cannot be stopped because the `pid' file that contains the
agent's process ID cannot be found, you can use *Note `kill': kill. to
send a `TERM' signal to the running process:

     shell> kill -TERM PID

If you are running more than one agent on a specific machine, you must
also specify the path to the `ini' file when you are stopping the
agent. Executing `mysql-monitor-agent stop' without an `ini' file will
only stop the agent associated with the default `ini' file.

For more information about creating additional agents see, *Note
mem-cfg-agent-ini::.

To verify that the agent is running use the following command:

     shell> ./mysql-monitor-agent status

The resulting message indicates whether the agent is running or not. If
the agent is not running, use the following command to view the last
ten entries in the agent log file:

     shell> tail /Applications/mysql/enterprise/agent/log/mysql-monitor-agent.log

For further information on troubleshooting the agent see *Note
mem-troubleshooting-agent-start::.

Installation creates the directory
`/Applications/mysql/enterprise/agent' with the settings stored in the
`mysql-monitor-agent.ini' file located directly below this directory in
the `etc' directory.  The `log' directory is also located immediately
below the `agent' directory.

To see all the command-line options available when running the service
agent, navigate to the `/Applications/mysql/enterprise/agent/etc/init.d'
directory and execute mysql-monitor-agent `help'. You should see the
message:

     Usage: ./mysql-monitor-agent {start|stop|restart|status} [ini-file-name]

The `ini-file-name' option only needs to be used if the `ini' file is
not installed to the default location or you have changed the name of
the `ini' file. You will need to use this option if you are installing
more than one agent on the same machine.  Pass the full path to the
`ini' file. For example, after navigating to the
`/Applications/mysql/enterprise/agent/etc/init.d' directory, issue the
command:

     shell> ./mysql-monitor-agent start /Applications/mysql/enterprise/agent/etc/NEW-MYSQL-MONITOR-AGENT.ini

If you installed the agent as `root', on reboot the
`mysql-monitor-agent' daemon will start up automatically. If you
installed the agent as an unprivileged user, you must manually start
the agent on reboot or write a script to perform this task. Likewise,
if you have added an additional agent as described in *Note
mem-cfg-agent-ini::, and you wish to start this agent on reboot, create
a system initialization script appropriate to your operating system. To
determine whether the agent is running or not navigate to the `init.d'
directory and issue the command ./mysql-monitor-agent status.

*Warning*:

To report its findings, the agent needs to be able to connect to the
dashboard through the port specified during installation. The default
value for this port is `18080'; ensure that this port is not blocked.
If you need help troubleshooting the agent installation see, *Note
mem-troubleshooting-agent-start::.


File: manual.info,  Node: mem-starting-agent-unix,  Prev: mem-starting-agent-osx,  Up: agent-starting-stopping

15.3.3.8 Starting/Stopping the Agent on Unix
............................................

When installation is finished, you can start the service agent from the
command line by typing:

     shell> /opt/mysql/enterprise/agent/etc/init.d/mysql-monitor-agent start

For a non-root installation the command would be:

     shell> /home/<user name>/mysql/enterprise/agent/etc/init.d/mysql-monitor-agent start

To stop the agent, use the `stop' command:

     shell> ./mysql-monitor-agent stop

If the agent cannot be stopped because the `pid' file that contains the
agent's process ID cannot be found, you can use *Note `kill': kill. to
send a `TERM' signal to the running process:

     shell> kill -TERM PID

If you are running more than one agent on a specific machine, you must
also specify the path to the `ini' file when you are stopping the
agent. Executing `mysql-monitor-agent stop' without an `ini' file will
only stop the agent associated with the default `ini' file.  Likewise,
when checking the status of an agent specify its `ini' file.

For more information about creating additional agents see, *Note
mem-cfg-agent-ini::.

To verify that the agent is running use the following command:

     shell> ./mysql-monitor-agent status

The resulting message indicates whether the agent is running or not. If
the agent is not running, use the following command to view the last
ten entries in the agent log file:

     shell> tail /opt/mysql/enterprise/agent/log/mysql-monitor-agent.log

For further information on troubleshooting the agent see *Note
mem-troubleshooting-agent-start::.

Installation creates the directory `/opt/mysql/enterprise/agent' with
the settings stored in the `mysql-monitor-agent.ini' file located
directly below this directory in the `etc' directory.  The `log'
directory is also located immediately below the `agent' directory.

To see all the command-line options available when running the service
agent, navigate to the `/opt/mysql/enterprise/agent/etc/init.d'
directory and execute mysql-monitor-agent `help'. You should see the
message:

     Usage: ./mysql-monitor-agent {start|stop|restart|status} [ini-file-name]

The `ini-file-name' option only needs to be used if the `ini' file is
not installed to the default location or you have changed the name of
the `ini' file. You will need to use this option if you are installing
more than one agent on the same machine.  Pass the full path to the
`ini' file. For example, after navigating to the
`/opt/mysql/enterprise/agent/etc/init.d' directory, issue the command:

     shell> ./mysql-monitor-agent start /opt/mysql/enterprise/agent/etc/NEW-MYSQL-MONITOR-AGENT.ini

If you installed the agent as `root', on reboot the
`mysql-monitor-agent' daemon will start up automatically. If you
installed the agent as an unprivileged user, you must manually start
the agent on reboot or write a script to perform this task. Likewise,
if you have added an additional agent as described in *Note
mem-cfg-agent-ini::, and you wish to start this agent on reboot, create
a system initialization script appropriate to your operating system. To
determine whether the agent is running or not navigate to the `init.d'
directory and issue the command ./mysql-monitor-agent status.

*Warning*:

To report its findings, the agent needs to be able to connect to the
dashboard through the port specified during installation. The default
value for this port is `18080'; ensure that this port is not blocked.
If you need help troubleshooting the agent installation see, *Note
mem-troubleshooting-agent-start::.


File: manual.info,  Node: mem-advanced-agent-configuration,  Next: mem-troubleshooting-agent-start,  Prev: agent-starting-stopping,  Up: mem-install-agent

15.3.3.9 Advanced Agent Configuration
.....................................

* Menu:

* mem-cfg-mysql-monitor-agent-ini::  MySQL Enterprise Monitor Agent (`mysql-monitor-agent.ini') Configuration
* mem-cfg-agent-ini::            MySQL Server (`agent-instance.ini') Configuration
* mem-install-agent-multiple::   Monitoring Multiple MySQL Servers
* mem-install-agent-remote::     Configuring an Agent to Monitor a Remote MySQL Server
* mem-ssh-tunnel::               Monitoring Outside the Firewall with an SSH Tunnel
* mem-install-new-uuid::         Generating a new UUID

The MySQL Enterprise Monitor Agent is configured through files located
within the `etc' directory within the directory where you installed the
agent.

Configuration is stored in multiple files, according to a predetermined
file and directory layout. The primary configuration file contains
specific information about the agent and how the agent communicates
with MySQL Enterprise Service Manager. The main configuration is
located within the `mysql-monitor-agent.ini' file.

Additional configuration files contain information about the MySQL
server that is being monitored. You can configure which directory is
used for storing this information within the `mysql-monitor-agent.ini'
file. The default location is the `etc/instances' directory within the
MySQL Enterprise Monitor Agent directory.

The server you want to monitor should have a directory within the
specified location, optionally using the name of the server you are
monitoring, and within that directory, an `agent-instance.ini' file.
This file contains the configuration information for connecting to the
MySQL server, including the host name, port, user credentials and
display name.

You can see an example of the file layout of the `etc' directory:

     .
     ./init.d
     ./init.d/mysql-monitor-agent
     ./instances
     ./instances/agent
     ./instances/agent/agent-instance.ini
     ./mysql-monitor-agent.ini

For more information on the configuration of the
`mysql-monitor-agent.ini' file, see *Note
mem-cfg-mysql-monitor-agent-ini::. For details on the content of the
individual MySQL instance configuration files, see *Note
mem-cfg-agent-ini::.


File: manual.info,  Node: mem-cfg-mysql-monitor-agent-ini,  Next: mem-cfg-agent-ini,  Prev: mem-advanced-agent-configuration,  Up: mem-advanced-agent-configuration

15.3.3.10 MySQL Enterprise Monitor Agent (`mysql-monitor-agent.ini') Configuration
..................................................................................

The `mysql-monitor-agent.ini' files contains the base configuration
information for the MySQL Enterprise Monitor Agent. The file sets the
core information about the supported functionality for the entire agent.

You can see a sample of the configuration file below:

     # WARNING - the UUID defined below must be unique for each agent.
     #
     # To use this .ini file as a template for configuring additional
     # agents, do not simply copy and start a new agent without first
     # modifying the UUID.
     #
     # Refer to the documentation for more detailed information and
     # instructions.
     #
     # Version: 20080718_230416_r7011

     [mysql-proxy]

     plugins=proxy,agent
     agent-mgmt-hostname = http://agent:password@monitor-server:18080/heartbeat
     mysqld-instance-dir= etc/instances
     agent-item-files = share/mysql-proxy/items/quan.lua,share/mysql-proxy/items/items-mysql-monitor.xml
     proxy-address=:4040
     proxy-backend-addresses = 127.0.0.1:3306
     proxy-lua-script        = share/mysql-proxy/quan.lua

     agent-uuid = 8770ead5-3632-4b29-a413-4a7c92437e26
     log-file = mysql-monitor-agent.log
     pid-file=/Applications/mysql/enterprise/agent/mysql-monitor-agent.pid

*Note*:

Do not copy the agent configuration information from one machine to
another without changing the `agent-uuid'. Each agent instance must
have a unique agent id.

The main configuration information must be located within the
`[mysql-proxy]' section of the configuration file. The main
configurable parameters within this file are:

   * `plugins' -- configures the plugins to be used by the agent. When
     monitoring servers you must have the `agent' plugin configured. If
     you want to support Query Analyzer then you must also have the
     `proxy' module enabled. Plugins should be specified as a comma
     separated list of plugin names.

     If you selected to support Query Analyzer during installation of
     the agent, the default value will be `proxy,agent'. If you
     disabled Query Analysis during installation, the default value
     will be `agent'.

   * `log-level' -- sets the logging level of the agent. The default
     level is `message'.

     Valid values for `log-level' are as follows:

        * `debug' -- provides detailed information about what the agent
          is doing and the information being provided by the agent to
          the MySQL Enterprise Service Manager.

        * `critical' -- lists critical messages highlighting problems
          with the agent.

        * `error' -- lists error messages.

        * `warning' -- provides only warning messages generated by the
          agent.

        * `message' -- provides information about the agent and basic
          processing information.

        * `info' -- provides messages used for informational purposes.

     *Warning*:

     Be careful when setting the `log-level' to `debug'. Doing this
     will rapidly increase the size of your `mysql-monitor-agent.log'
     file. To avoid disk space problems, put the log files on a
     different drive from your MySQL server and the MySQL Enterprise
     Dashboard.

     It is strongly recommended that you use a `log-level' of
     `critical' or `error' in a production server. Use the
     higher-levels to provide more detailed information only for
     debugging problems with your agent.

     Under Windows, if you restart the agent from the command line
     after setting the `log-level' to `debug', extensive debug
     information is displayed to the console as well as to the log file.

   * `agent-mgmt-hostname' -- sets the URL to use when reporting
     information. This value will be automatically set to your MySQL
     Enterprise Service Manager during installation.

   * `mysqld-instance-dir' -- sets the directory where the
     configuration files that specify the MySQL servers to be monitored
     can be located.

   * `agent-item-files' -- sets the information that is provided up to
     the MySQL Enterprise Service Manager when the agent is reporting
     status information. You should leave this item with the default
     setting of the `share/mysql-proxy/items/quan.lua' (which provides
     Query Analyzer data) and
     `share/mysql-proxy/items/items-mysql-monitor.xml' (which provides
     the core agent monitoring data).

   * `proxy-address' -- sets the address and/or port number for the
     proxy to listen to for connections. The setting is used when
     employing Query Analysis as the address/port that you must
     configure your application to use in place of your normal MySQL
     server. By default this item is set during installation. The
     default value is 4040. If you want to support a different local
     host name/IP address and port, specify the host name and the port
     number, separated by a colon.

   * `proxy-backend-addresses' -- sets the host name and port number to
     be used when communicating the backend MySQL server when employing
     query analyzer. This is the MySQL server where packets from the
     client are sent when communicating with the proxy on the host
     name/port set by the `proxy-address'.

   * `proxy-lua-script' -- sets the Lua script to be used by the proxy
     when forwarding queries. To use Query Analyzer, this parameter
     should be set to `share/mysql-proxy/quan.lua'. This is the default
     value.

   * `agent-uuid' -- sets the UUID (Universally Unique ID) of the
     agent. This value should be unique for all agents communicating
     with the same server, as the UUID is used to uniquely ID the agent
     within MySQL Enterprise Service Manager

     If you are setting up multiple hosts and copying the configuration
     between hosts, make sure that the `agent-uuid' is unique. You can
     have the agent create a new UUID by leavig this configuration
     property blank.

   * `log-file' -- sets the location of the log file used to record
     information about the agent when it is running. If you do not
     specify a full path name, then the log file location is considered
     to be relative to the installation directory of the agent.

   * `pid-file' -- sets the location of the file used to record the
     Process ID of the agent. This is used by the script that shuts
     down the agent to identify the process to be shutdown. The default
     value is the `mysql-monitor-agent.pid' file within the base
     installation directory as created by the agent installer.

A number of optional parameters are also configurable within the
`mysql-monitor-agent.ini' file:

   * `backlog-threshold' -- determines the amount of time that the
     agent will collect information after detecting that the service
     manager is down. The default value for this option is 600 seconds.
     In cases where there is a short network outage no information will
     be lost. If the outage is longer than the value of
     `backlog-threshold' older data is dropped as the new data is
     acquired.

     A setting of 600 seconds means that excessive memory usage is
     avoided should there be a long outage. In most circumstances,
     there is no need to change this option. To set `backlog-threshold'
     to a value other than the default, add a line with the information
     specifying the number of seconds.

     *Warning*:

     Setting this option to a value higher than the default can exhaust
     memory.


File: manual.info,  Node: mem-cfg-agent-ini,  Next: mem-install-agent-multiple,  Prev: mem-cfg-mysql-monitor-agent-ini,  Up: mem-advanced-agent-configuration

15.3.3.11 MySQL Server (`agent-instance.ini') Configuration
...........................................................

For the MySQL server that you want to monitor, you must create an
`agent-instance.ini' within the directory specified by the
`mysqld-instance-dir' configuration parameter within the main
`mysql-monitor-agent.ini' file.

The `agent-instance.ini' file contains the host name and user
credentials for connecting to the MySQL server that you want the agent
to monitor. The format of the file is as follows:

     # WARNING - the displayname defined below must be unique for each
     # MySQL server being monitored.
     #
     # To use this .ini file as a template for configuring additional
     # instances to monitor, do not simply copy and start a new agent
     # without first modifying the displayname.
     #
     # Refer to the documentation for more detailed information and
     # instructions.
     #
     # Version: 20080718_230416_r7011

     [mysqld]
     hostname = 127.0.0.1
     port     = 3306
     user     = root
     password =

The individual configuration parameters can be defined as follows:

   * `hostname' -- the host name of the MySQL server that you want to
     monitor.

   * `port' -- the TCP/IP port of the MySQL server that you want to
     monitor.

   * `user' -- the user to use when connecting to the MySQL server that
     you want to monitor.

   * `password' -- the corresponding password to use when connecting to
     the MySQL server that you want to monitor.

It is also possible to configure the agent to use sockets. This can be
done during installation by selecting `socket' rather than `TCP/IP'
from the menu and then specifying the socket name. This can also be
configured after installation by editing the `agent-instance.ini'
configuration file, and adding the line:

     socket = /full/path/to/mysql.sock


File: manual.info,  Node: mem-install-agent-multiple,  Next: mem-install-agent-remote,  Prev: mem-cfg-agent-ini,  Up: mem-advanced-agent-configuration

15.3.3.12 Monitoring Multiple MySQL Servers
...........................................

You can monitor multiple MySQL servers (either on the same machine, or
across different machines) using two different methods:

   * By using a single agent instance to monitor multiple MySQL
     servers. You can use this method if you want to monitor multiple
     servers, but do not want or need to support Query Analysis on the
     additional servers.

   * By using multiple copies of the MySQL Enterprise Monitor Agent to
     monitor each server individually. Using this method requires
     additional overhead to monitor each server, while also allowing
     you to supply Query Analysis data.

*Using a Single Agent Instance*

To use a single agent to monitor multiple instances, you can create
additional directories and configuration files within the `instances'
directory for the agent. For example, you can see the default structure
of the agent configuration directory:

     ./init.d
     ./init.d/mysql-monitor-agent
     ./instances
     ./instances/agent
     ./instances/agent/agent-instance.ini
     ./mysql-monitor-agent.ini

Within the `instances' directory, you can add further directories, one
for each monitored server. Each additional directory must have a
suitable `agent-instance.ini' file containing the connection
information for the new MySQL server instance. For example, the
following structure demonstrates an agent monitoring four MySQL servers:

     ./init.d
     ./init.d/mysql-monitor-agent
     ./instances
     ./instances/agent
     ./instances/agent/agent-instance.ini
     ./instances/mysql2
     ./instances/mysql2/agent-instance.ini
     ./instances/mysql-rep
     ./instances/mysql-rep/agent-instance.ini
     ./instances/mysql-backup
     ./instances/mysql-backup/agent-instance.ini
     ./mysql-monitor-agent.ini

To add another MySQL monitored server, follow these steps:

  1. Make sure that the MySQL instance that you want to monitor has a
     suitable user to use for connecting to the server. For more
     information, see *Note mem-agent-rights::.

  2. Copy an existing configuration directory and configuration files
     to the new directory:

          shell> cp -R etc/instances/agent etc/instances/MYSQL2

  3. Edit the configuration file within the new directory, for example
     `mysql2/agent-instance.ini', and set the `user', `password' and
     either the `hostname' and `port', or `socket' parameters.

  4. Restart the agent:

          shell> mysql-monitor-agent restart

*Using Multiple Agent Instances*

To use multiple agents to monitor multiple MySQL servers you need to
create a new configuration structure for both the agent and the MySQL
server instances you need to monitor, including the binaries and
configuration files, and then update the configuration to set the
corresponding parameters to monitor the new server. Using this method
allows you to enable query analyis by redirecting requests to the
target server using the built-in proxy service within the agent.

For example, the directory structure below shows the configuration
directory for two agents monitoring a single MySQL server each:

     ./init.d
     ./init.d/mysql-monitor-agent
     ./instances
     ./instances/agent
     ./instances/agent/agent-instance.ini
     ./instances-second/agent
     ./instances-second/agent/agent-instance.ini
     ./mysql-monitor-agent.ini
     ./mysql-second-agent.ini

The `mysql-monitor-agent.ini' file contains the configuration for the
first agent, with the MySQL servers monitored defined within the
`instances' directory. The `mysql-second-agent.ini' file contains the
configuration information for the second agent, with the MySQL servers
monitor defined within the `instances-second' directory.

To set up multiple agents:

  1. Make sure that the MySQL instance that you want to monitor has a
     suitable user to use for connecting to the server. For more
     information, see *Note mem-agent-rights::.

  2. You need to generate a new UUID for the new agent:

          shell> mysql-monitor-agent --agent-generate-uuid
          ee9296d7-f7cd-4fee-8b26-ead884ebf398
          2009-03-05 11:49:37: (critical) shutting down normally

     Keep a record of the UUID to update the configuration file.

     Note, the agent should not be running when the UUID is generated.

  3. Copy the main agent configuration file, `mysql-monitor-agent.ini':

          shell> cp mysql-monitor-agent.ini MYSQL-SECOND-AGENT.INI

  4. Edit the new configuration file, changing the following settings:

        * Change the `mysqld-instance-dir' to the new directory that
          will contain the individual MySQL server configuration files.

        * Change the `proxy-address' to a different value than the
          first agent configuration.

        * Change the `proxy-backend-addresses' to specify the IP
          address and MySQL port number for the MySQL server.

        * Change the `agent-uuid' to the new value obtained in an
          earlier step.

        * Change the `log-file' parameter to specify a different file
          to use when logging errors and problems. You cannot log to
          the same file from two different agents.

        * Change the `pid-file' parameter to specify the file that will
          be used to store the process ID of the agent.

  5. Copy an existing configuration directory and configuration files
     to the new directory:

          shell> cp -R etc/instances etc/INSTANCES-SECOND

  6. Edit the configuration file,
     `instances/second/agent/agent-instance.ini' within the new
     directory, and set the `user', `password' and either the
     `hostname' and `port', or `socket' parameters.

  7. With multiple instances, you must start each agent individually,
     specifying the location of the main configuration file. For
     example, to start the original (default) service:

          shell> mysql-monitor-agent start /opt/mysql/monitor/agent/etc/mysql-monitor-agent.ini

     To start the second instance:

          shell> mysql-monitor-agent start /opt/mysql/monitor/agent/etc/mysql-second-agent.ini


File: manual.info,  Node: mem-install-agent-remote,  Next: mem-ssh-tunnel,  Prev: mem-install-agent-multiple,  Up: mem-advanced-agent-configuration

15.3.3.13 Configuring an Agent to Monitor a Remote MySQL Server
...............................................................

Typically, the agent runs on the same machine as the MySQL server it is
monitoring. Fortunately, this is not a requirement.  If you want to
monitor a MySQL server running on an operating system for which there
is no agent available, you can install the agent on a machine other
than the one hosting the MySQL server.

The process for installing an agent to monitor a MySQL server on a
remote machine is identical to the process described in *Note
mem-install-agent::. Follow the directions given there, being careful
to specify the correct IP address or host name for the MySQL Enterprise
Service Manager and likewise for the MySQL server -- since the agent is
not running on the same machine as the MySQL server, it cannot be the
default, `localhost'.

Don't forget that the agent must be given rights to log in to the MySQL
server from a host other than `localhost' and that the port used by the
MySQL server, typically `3306' must be open for remote access. For more
information about the database credentials required by agents see,
*Note mem-agent-rights::.

The agent also needs to be able to log in to the MySQL Enterprise
Service Manager, typically using port `18080', so ensure that the
appropriate port is open.

*Note*:

Monitoring a MySQL server from a remote machine affects how information
is displayed in the dashboard. The `OS' and `CPU' information applies
to the machine on which the agent is running not the machine hosting
the monitored server. For more information on this topic see *Note
mem-dashboard::.

If your subscription level entitles you to replication autodiscovery,
do *not* use remote monitoring with replication slaves or masters. The
agent must be installed on the same machine as the server you are
monitoring in order for discovery to work properly. For more
information, see *Note mem-replication::.


File: manual.info,  Node: mem-ssh-tunnel,  Next: mem-install-new-uuid,  Prev: mem-install-agent-remote,  Up: mem-advanced-agent-configuration

15.3.3.14 Monitoring Outside the Firewall with an SSH Tunnel
............................................................

If you run an SSH server on the machine that hosts the MySQL Enterprise
Service Manager and an SSH client on the machine that hosts the agent,
you can create an SSH tunnel so that the agent can bypass your
firewall. First, you need to make an adjustment to the `hostname' value
specified in the `[mysql-proxy]' section of the `.ini' file. (For more
information about the contents and location of the `.ini' file see
*Note mem-cfg-mysql-monitor-agent-ini::.) Stop the agent and change the
`hostname' value as shown in the following:

     hostname = http://AGENT_NAME:PASSWORD@localhost:18080/heartbeat

Replace the `agent_name' and `password' with suitable values. Likewise
replace port `18080' if you are not running the dashboard on this port.
Use `localhost' for the host name, since the agent is connecting
through an SSH tunnel.

Next, execute the following command on the machine where the agent is
running:

     shell> `ssh -L 18080:DASHBOARD_HOST:18080 -l USER_NAME -N DASHBOARD_HOST'

When prompted, enter the password for USER_NAME.

If you are not running the MySQL Enterprise Service Manager on port
`18080', substitute the appropriate port number. Likewise, replace
`Dashboard_Host' with the correct value. `user_name' represents a valid
operating system user on the machine that hosts the MySQL Enterprise
Service Manager.

Be sure to restart the agent so that the new value for the `hostname'
takes effect. For instructions on restarting the agent see:

   * Under Windows see, *Note mem-starting-agent-windows::.

   * Under Unix see, *Note mem-starting-agent-unix::.

   * Under Mac OS X see, *Note mem-starting-agent-osx::.


File: manual.info,  Node: mem-install-new-uuid,  Prev: mem-ssh-tunnel,  Up: mem-advanced-agent-configuration

15.3.3.15 Generating a new UUID
...............................

In Unix go to the command line and type:

     shell> /opt/mysql/enterprise/agent/bin/mysql-monitor-agent --agent-generate-uuid

In Mac OS X go to the command line and type:

     shell> /Applications/mysql/enterprise/agent/bin/mysql-monitor-agent --agent-generate-uuid

This should display a line similar to the following:

     ee9296d7-f7cd-4fee-8b26-ead884ebf398

Paste this line into the `[mysql-proxy]' section of the `ini' file for
the `agent-uuid' parameter.

Ensure that the newly created file `mysql-service-agent-3307.ini', is
in the `C:\Program Files\MySQL\Enterprise\Agent' directory.

Navigate to this directory and execute `mysql-service-agent -uf
mysql-service-agent-3307.ini'. Doing this generates a new UUID and
inserts it into the configuration file.


File: manual.info,  Node: mem-troubleshooting-agent-start,  Prev: mem-advanced-agent-configuration,  Up: mem-install-agent

15.3.3.16 Troubleshooting the Agent
...................................

The first step in troubleshooting the agent is finding out whether it
is running or not. To do this see:

   * Windows - *Note mem-starting-agent-windows::

   * Unix - *Note mem-starting-agent-unix::

   * Mac OS X - *Note mem-starting-agent-osx::

If incorrect credentials are specified for the agent login to the MySQL
server that it is monitoring, then the agent will not run on start-up.
Log in to the monitored MySQL server and check the agent's credentials.
Compare the values of the `Host', `User', and `Password' fields in the
`mysql.user' table with the values shown in the `[mysqld]' section of
the `etc/instances/mysql/agent-instance.ini'. If incorrect credentials
are specified in the `ini' file, simply correct them and restart the
agent. Remember, changes to the `ini' file do not take effect until the
agent is restarted.

The agent will not start up if incorrect credentials are specified for
the service manager login. Using incorrect credentials for logging in
to the service manager creates an entry in the agent log file. For the
location of this log file see Agent Log and PID Files
(http://dev.mysql.com/doc/mysql-monitor/2.0/en/mem-agent-log-and-pid-files.html).

If the agent starts up but no server appears in the dashboard, check
the `hostname' specified in the `[mysql-proxy]' portion of the
`mysql-monitor-agent.ini' file. Incorrect credentials, IP address, or
port will all cause the MySQL server to fail to appear in the
dashboard. Also, ensure that the port specified in this file is not
blocked on the machine hosting the MySQL Enterprise Service Manager.

An easy way to confirm that the agent can log in to the service manager
is to type http://DASHBOARD_HOST:18080/heartbeat into the address bar
of your web browser, substituting the appropriate host name and port.
When the HTTP authentication dialog box opens, enter the agent user
name and password. If you log in successfully, you should see the
following message:

     <exceptions>
     <error>E1031:  Agent payload parameter NULL.</error>
     </exceptions>

*Note*:

Despite the fact that the preceding listing shows an error, you have
logged in successfully. This error appears _because_ you have logged in
but with no `payload'.

If you can log in successfully in the way described above and the agent
is running, then there are errors in the `mysql-monitor-agent.ini'
file. Compare the host name, port, agent name, and password found in the
`ini' file with the values you entered into the address bar of your web
browser.

If HTTP authentication fails then you are using incorrect credentials
for the agent. Attempting to log in to the service manager using
incorrect credentials creates an entry in the agent log file. For the
location of this log file see Agent Log and PID Files
(http://dev.mysql.com/doc/mysql-monitor/2.0/en/mem-agent-log-and-pid-files.html).

If no HTTP authentication dialog box appears, and you are unable to
connect at all, then you may have specified an incorrect host name or
port. Confirm the values you entered against those described as the
`Application hostname and port:' in the `configuration_report.txt'
file. Failure to connect could also indicate that the port is blocked
on the machine hosting the MySQL Enterprise Service Manager.

To check if a blocked port is the problem, temporarily bring down your
firewall. If the agent is then able to connect, open up the port
specified during installation and restart the agent. If necessary you
can monitor outside the firewall using an SSH tunnel. For more
information, see *Note mem-ssh-tunnel::.

You can also check the agent error log file to help determine any
problems. An error such as the following might indicate a blocked port:

     (critical) connection to  merlin-server
     'http://AGENT:TEST@172.11.1.1:18080/heartbeat' failed:
     "connect() timed out!" error.

For the location of the agent error log file see, Agent Log and PID
Files
(http://dev.mysql.com/doc/mysql-monitor/2.0/en/mem-agent-log-and-pid-files.html).

Setting the `log-level' entry in your `ini' file is also a good
debugging technique.  For more information on this subject see, *Note
mem-cfg-mysql-monitor-agent-ini::.

Running the agent from the command line sometimes displays errors that
fail to appear in the log file or on the screen when the agent is
started from a menu option. To start the agent from the command line
see the instructions given at the start of this section.

If you have more than one agent running on the same machine, the `UUID'
must be unique and the `log-file' and `pid-file' values must be
different. For more information, see *Note mem-cfg-agent-ini::.

If the agent is not running on the same machine that hosts the MySQL
server it is monitoring, then you must ensure that the correct `host'
is specified for the agent account. The correct port, typically 3306,
must also be open for remote login. For more information about remote
monitoring see, *Note mem-install-agent-remote::.


File: manual.info,  Node: mem-unattended-installation,  Next: mem-install-post-installation,  Prev: mem-install-agent,  Up: mem-install

15.3.4 Unattended Installation
------------------------------

* Menu:

* mem-command-line-options-monitoring::  Command-Line Options
* mem-unattended-windows::       Unattended Windows Installation
* mem-unattended-unix-osx::      Unattended Unix and Mac OS X Installation
* mem-unattended-install-starting-services::  Starting the Services

It is possible to install the MySQL Enterprise Monitor without any
direct user interaction. This is done by passing the command-line option
`--mode unattended' to the installation file.

Using this mode and other command-line parameters means the user will
not be prompted for input during installation. This is especially
useful when doing multiple installations of the MySQL Enterprise
Monitor.

However, rather than passing numerous parameters from the command line,
it is usually more convenient to save your options in a text file and
invoke the installer using the `optionfile' option. This is a more
reusable and less error-prone solution.

Before attempting an unattended installation, it is recommended that
you install the MySQL Enterprise Monitor interactively at least once.
Failing this, as a minimum, read the regular installation instructions
since some tasks still remain after an unattended installation; you must
configure the MySQL Enterprise settings, import the advisors, and start
up all the services/daemons.


File: manual.info,  Node: mem-command-line-options-monitoring,  Next: mem-unattended-windows,  Prev: mem-unattended-installation,  Up: mem-unattended-installation

15.3.4.1 Command-Line Options
.............................

* Menu:

* mem-command-line-options-server::  MySQL Enterprise Service Manager Options
* mem-command-line-options-service-agent::  MySQL Enterprise Monitor Agent Options

To view the available options for the monitor installer or for the
agent installer, at the command line type the executable file name
along with the `help' option.


File: manual.info,  Node: mem-command-line-options-server,  Next: mem-command-line-options-service-agent,  Prev: mem-command-line-options-monitoring,  Up: mem-command-line-options-monitoring

15.3.4.2 MySQL Enterprise Service Manager Options
.................................................

The following listing shows the command line options for the MySQL
Enterprise Service Manager.

     --help                         Display the list of valid options

     --version                      Display product information

     --optionfile <optionfile>      Installation option file

                                    Default:

     --mode <mode>                  Installation mode

                                    (Windows)Default: win32
                                    (Unix)Default: gtk
                                    (Mac OS X)Default: osx
                                    (Windows)Allowed: win32 unattended
                                    (Unix)Allowed: gtk text xwindow unattended
                                    (Mac OS X)Allowed: osx text unattended

*Note*:

The default modes are different for different operating systems. The
values allowed also differ. There is no `text' installation mode under
Windows.

     --debugtrace <debugtrace>      Debug filename
                                    Default:

     --installer-language <installer-language> Language selection
                                    Default:
                                    Allowed: en  jp

     --installdir <installdir>      Installation directory
                                    (Windows)Default:C:\Program »
                                    Files\MySQL\Enterprise\Monitor
                                    (Unix)Default:/opt/mysql/enterprise/monitor/
                                    (Mac OS X)Default:/Applications/mysql/enterprise/monitor/

     --tomcatport <tomcatport>      Tomcat Server Port
                                    Default: 18080

     --tomcatshutdownport <tomcatshutdownport> Tomcat Shutdown Port
                                    Default: 18005

     --tomcatsslport <tomcatsslport>Tomcat SSL Port
                                    Default: 18443

     --usessl <usessl>              Should communication between the Dashboard »
                                           and Service Manager be encrypted?
                                    Default: 0

     --adminuser <adminuser>        Repository Username
                                    Default: service_manager

     --adminpassword <adminpassword>Password
                                    Default:

*Warning*:

The repository user name and password are stored in unencrypted form in
the `config.properties' file. To locate this file on your operating
system see The `config.properties' File
(http://dev.mysql.com/doc/mysql-monitor/2.0/en/mem-config-properties-file-location.html).


     --dbport <dbport>              Bundled MySQL Database Port
                                    Default: 13306

The monitor installation options are the same for all operating systems
except as noted in the preceding listing.


File: manual.info,  Node: mem-command-line-options-service-agent,  Prev: mem-command-line-options-server,  Up: mem-command-line-options-monitoring

15.3.4.3 MySQL Enterprise Monitor Agent Options
...............................................

To view all the options available for an unattended _agent_
installation, invoke the agent installer file passing in the `help'
option.  (Under Windows you must redirect the output to a file as shown
in *Note mem-command-line-options-monitoring::). You should see a
listing similar to the following:

     --help                         Display the list of valid options

     --version                      Display product information
                                    Default:

     --optionfile <optionfile>      Installation option file
                                     Default:

     --mode <mode>                  Installation mode
                                    (Windows)Default: win32
                                    (Unix)Default: gtk
                                    (Mac OS X)Default: osx
                                    (Windows)Allowed: win32 unattended
                                    (Unix)Allowed: gtk text xwindow unattended
                                    (Mac OS X)Allowed: osx text unattended

*Note*:

The default modes are different for different operating systems. The
values allowed also differ. There is no `text' installation mode under
Windows.

     --debugtrace <debugtrace>      Debug filename
                                    Default:

     --installer-language <installer-language> Language selection
                                    Default:
                                    Allowed: en  jp

     --installdir <installdir>      Installation directory
                                    (Windows)Default: C:\Program Files\MySQL\Enterprise\Agent
                                    (Unix)Default:/opt/mysql/enterprise/agent
                                    (Mac OS X)Default:/Applications/mysql/enterprise/agent

     --mysqlhost <mysqlhost>         MySQL hostname or IP address
                                     Default: 127.0.0.1

     --checkmysqlhost <checkMysqlhost>Validation of MySQL hostname or IP address
                                     Default: yes

     --mysqlport <mysqlport>         MySQL port on 127.0.0.1
                                     Default: 3306

     --mysqluser <mysqluser>         User name on 127.0.0.1:3306
                                     Default:

     --mysqlpassword <mysqlpassword> Password for mysqluser on 127.0.0.1:3306
                                     Default:

     --managerhost <managerhost>     Hostname or IP address
                                     Default: 127.0.0.1

     --tomcatport <tomcatport>       Port on 127.0.0.1
                                     Default: 18080

     --agentuser <agentuser>         Agent username on 127.0.0.1:18080
                                     Default: agent

     --agentpassword <agentpassword> Agent password for AGENT on 127.0.0.1:18080
                                     Default:

     --servername <servername>       Hostname to display
                                     Default:

Again, the agent options are the same for all operating systems except
as noted.


File: manual.info,  Node: mem-unattended-windows,  Next: mem-unattended-unix-osx,  Prev: mem-command-line-options-monitoring,  Up: mem-unattended-installation

15.3.4.4 Unattended Windows Installation
........................................

For unattended installation on Windows, create an option file named
`options.server.txt'. The following is an example of what the contents
of an option file might be.

     debugtrace=C:\Program Files\MySQL\Enterprise\install.debugtrace.log
     mode=unattended
     installdir=C:\Program Files\MySQL\Enterprise
     tomcatport=8080
     tomcatshutdownport=8005
     tomcatsslport=8443
     adminpassword=myadminpassword
     dbport=3300

This file identifies a directory and file name for a log file, sets the
`mode' to `unattended', and uses the `installdir' option to specify an
installation directory. The meaning of the other options is fairly
self-evident.

*Note*:

Set the `installdir' and `debugtrace' options to values appropriate to
your locale and operating system.

The only options that must be specified in an option file when
installing the MySQL Enterprise Service Manager are `mode' (if not
specified at the command line), `installdir', and `adminpassword'.

Check the options in your option file closely before installation; no
warnings will be issued if there are errors.

Ensure that the monitor installer file and the options file are in the
same directory and, if you saved the options file as
`options.server.txt', you can invoke an unattended installation from
the command line by typing:

       C:\ mysqlmonitor-VERSION-windows-installer.exe --optionfile options.server.txt

You can install the MySQL Enterprise Monitor Agent in exactly the same
fashion.  Create an agent option file and call the agent installer
using the `optionfile' option.

As a minimum for the agent installation, you must specify the `mode'
(if not specified at the command line), `mysqluser', `installdir',
`mysqlpassword', `installdir', `managerhost', and `agentpassword'
options. Create a file containing these values and use it with the
`optionfile' option for unattended agent installation.

If you wish, you can create one script that calls both the Service
Manager and the Monitor Agent programs passing appropriate `optionfile'
options.


File: manual.info,  Node: mem-unattended-unix-osx,  Next: mem-unattended-install-starting-services,  Prev: mem-unattended-windows,  Up: mem-unattended-installation

15.3.4.5 Unattended Unix and Mac OS X Installation
..................................................

For unattended installation on Unix, create an option file named
`options.server.txt'. The following is an example of what the contents
of an option file might be for installation on Unix.

     debugtrace=/opt/mysql/enterprise/install.debugtrace.monitor.log
     mode=unattended
     installdir=/opt/mysql/enterprise/monitor
     tomcatport=8080
     tomcatshutdownport=8005
     tomcatsslport=8443
     adminpassword=myadminpassword
     dbport=3300

This file identifies a directory and file name for a log file, sets the
`mode' to `unattended', and uses the `installdir' option to specify an
installation directory. The meaning of the other options is fairly
self-evident.

*Note*:

Set the `installdir' and `debugtrace' options to values appropriate to
your locale and operating system.

The only options that must be specified in an option file when
installing the MySQL Enterprise Service Manager are `mode' (if not
specified at the command line), `installdir', and `adminpassword'.

Check the options in your option file closely before installation; no
warnings will be issued if there are errors.

Ensure that the monitor installer file and the options file are in the
same directory and, if you saved the options file as
`options.server.txt', you can invoke an unattended installation from
the command line by typing:

       shell> mysqlmonitor-VERSION-installer.bin --optionfile options.server.txt

You can install the MySQL Enterprise Monitor Agent in exactly the same
fashion.  Create an agent option file and call the agent installer
using the `optionfile' option.

As a minimum for the agent installation, you must specify the `mode'
(if not specified at the command line), `mysqluser', `installdir',
`mysqlpassword', and `agentpassword' options. Create a file containing
these values and use it with the `optionfile' option for unattended
agent installation.

If you wish, you can create one script that calls both the Service
Manager and the Monitor Agent programs passing appropriate `optionfile'
options.

*Note*:

The Service Manager does not automatically start up on rebooting. For
more information, see Bug#31676 (http://bugs.mysql.com/31676).

The procedure for unattended agent installation under Mac OS X is
identical to the procedure under Unix.


File: manual.info,  Node: mem-unattended-install-starting-services,  Prev: mem-unattended-unix-osx,  Up: mem-unattended-installation

15.3.4.6 Starting the Services
..............................

For instructions on starting the services needed by the MySQL
Enterprise Service Manager see, *Note mem-server-starting-windows:: for
Windows and, *Note mem-server-starting-unix-osx:: for Unix and Mac OS X.

For instructions on starting the MySQL Enterprise Monitor Agent see:

   * Windows - *Note mem-starting-agent-windows::

   * Unix - *Note mem-starting-agent-unix::

   * Mac OS X - *Note mem-starting-agent-osx::

If you wish, you can script the startup of these services.


File: manual.info,  Node: mem-install-post-installation,  Next: mem-upgradeorchange,  Prev: mem-unattended-installation,  Up: mem-install

15.3.5 Post-Installation Considerations
---------------------------------------

Depending upon how you plan to use the MySQL Enterprise Monitor, there
are some tasks you may want to perform after installation. Find some
suggestions in the following list:

   * *Email settings* -- Test email notification by deliberately
     triggering an alert.

   * *Auto Startup* -- On Unix systems, the MySQL Enterprise Service
     Manager does not automatically restart when the system is
     rebooted. You may wish to create a system initialization script
     appropriate to your operating system.

   * *Log files* -- Check the log files for any irregularities. For the
     locations of the various log files see Files Associated with The
     MySQL Enterprise Monitor
     (http://dev.mysql.com/doc/mysql-monitor/2.0/en/mem-files.html).

   * *Agent Log file rotation* -- Implement log file rotation for the
     service agent.

   * *Back up the repository* -- For a back-up strategy suitable to
     your circumstances, see the MySQL reference manual documentation
     (http://dev.mysql.com/doc/).

   * *Configuration backup* -- Back up the `mysql-monitor-agent.ini'
     file and the associated `instances' directory and contents.

     For more information about the `mysql-monitor-agent.ini' file see
     *Note mem-advanced-agent-configuration::.

   * *Configuration file* -- Store the `configuration_report.txt' in a
     safe place. There is no mechanism for retrieving the password
     stored in this file.

   * *Repository credentials* -- The repository user name and password
     are stored in unencrypted form in the `config.properties' file.
     Take care to protect this file.

   * *Disk management* -- Remove installation files, and monitor the
     space used by the repository. Ensure that you have adequate disk
     space by regularly purging data. For more information, see *Note
     mem-data-purge::.

   * *Firewall changes* -- You may want to limit or expand access to
     the MySQL Enterprise Service Manager.

   * *Open ports* -- As with firewall changes, you may want to limit or
     expand access to the MySQL Enterprise Service Manager. The
     dashboard uses non-standard ports, none of which are usually open
     by default.

   * *Server upgrades* -- See *Note mem-ungrading-monitored-server:: for
     instructions on upgrading a server.

   * *Repository access* -- You may want to add other users.


File: manual.info,  Node: mem-upgradeorchange,  Next: mem-uninstall,  Prev: mem-install-post-installation,  Up: mem-install

15.3.6 Upgrading, Re-Installing or Changing Your Installation
-------------------------------------------------------------

* Menu:

* mem-upgrading::                Upgrading MySQL Enterprise Monitor
* mem-reinstalling-mysqlmonitor::  Reinstalling MySQL Enterprise Monitor
* mem-changing-installation::    Changing Your MySQL Enterprise Monitor Installation

You can upgrade

   * For instructions on upgrading your existing installation, see
     *Note mem-upgrading::.

   * For more information on re-installing an existing installation,
     see *Note mem-reinstalling-mysqlmonitor::.

   * To change an existing installation, such as changing the monitored
     server, see *Note mem-changing-installation::.


File: manual.info,  Node: mem-upgrading,  Next: mem-reinstalling-mysqlmonitor,  Prev: mem-upgradeorchange,  Up: mem-upgradeorchange

15.3.6.1 Upgrading MySQL Enterprise Monitor
...........................................

* Menu:

* mem-upgrading-2.0::            Upgrading from MySQL Enterprise Monitor 1.3 to 2.0
* mem-unattended-update::        Unattended MySQL Enterprise Monitor Update

From time to time there may be updates to the MySQL Enterprise Service
Manager or the MySQL Enterprise Monitor Agent. This section describes
how to perform an update for either of these components.

You cannot use the update installers to change to a different operating
system or chip architecture. For example, you cannot update a 32-bit
Linux installation to a 64-bit version using an update installer -- in
cases such as this you must do a fresh installation.

The name of the update file varies but it shows the target operating
system and the version the update applies to. If a specific component
is being updated it may also appear in the file name. For example, a
file named `MYSQLENTERPRISEMANAGER-2.0.0-WINDOWS-UPDATE-INSTALLER.EXE'
would indicate a Windows update to MySQL Enterprise Service Manager
version 2.0.0.

You may install an update in the same way that you initially installed
the service manager or the agent; in `win32' or `unattended' mode on
Windows in `gtk', `text', `xwindow', or `unattended' mode on Unix and
in `osx', `text ', or `unattended' mode on OS X.

*Warning*:

Before updating the MySQL Enterprise Service Manager stop all agents
that are reporting to that MySQL Enterprise Service Manager. If you are
updating the MySQL Enterprise Monitor Agent you must also stop the
MySQL Enterprise Service Manager. On a machine that runs more than one
agent, the primary agent will restart when the update is complete. Any
secondary agents must be restarted manually. To stop or start agents
see:

   * Windows - *Note mem-starting-agent-windows::

   * Unix - *Note mem-starting-agent-unix::

   * Mac OS X - *Note mem-starting-agent-osx::

*Important*:

The upgrade installer will overwrite `items-mysql-monitor.xml'. On
Windows this file is found in the `C:\Program
Files\MySQL\Enterprise\Agent\share\mysql-monitor-agent' directory and
on Unix in the `/opt/mysql/enterprise/agent/share/mysql-monitor-agent'
directory. You should back this file up if you have made any changes to
it.

*Warning*:

If you use the Upgrade installer to update MySQL Enterprise Service
Manager and you have made any changes to the `my.cnf' within your MySQL
Enterprise Service Manager installation, any changes will be lost. You
should copy the existing `my.cnf' file before starting the upgrade
installer.

Otherwise, updating is a fairly straightforward process. Run the
installation file and choose the directory of your current installation
and whether or not you wish to back up your current installation. The
time required to complete the process varies depending upon the nature
of the update.

If you chose to back up your current installation, a directory named
`backup' will be created in the current installation directory. This
directory will contain copies of the directory or directories that were
replaced during the update. In cases where only specific files are
replaced, the `backup' directory may contain only these files. If you
are unhappy with the update simply overwrite the new files or
directories with the originals found in the `backup' directory. Be sure
to stop both the MySQL Enterprise Service Manager and MySQL Enterprise
Monitor Agent before restoring the original files. You can delete or
archive this directory when you are satisfied that the update was
successful.

If you choose to back up your current installation, the installer
checks that there is adequate disk space for your repository backup. If
there is not enough space, you are given the option of choosing another
location; you may also choose not to back up the repository.

To update your Advisors see, *Note mem-upgrading-updating-advisors::.


File: manual.info,  Node: mem-upgrading-2.0,  Next: mem-unattended-update,  Prev: mem-upgrading,  Up: mem-upgrading

15.3.6.2 Upgrading from MySQL Enterprise Monitor 1.3 to 2.0
...........................................................

* Menu:

* mem-upgrading-2.0-server::     Upgrading to MySQL Enterprise Service Manager 2.0
* mem-upgrading-2.0-agent::      Upgrading to MySQL Enterprise Monitor Agent 2.0

To upgrade your existing installation from MySQL Enterprise Monitor 1.3
to MySQL Enterprise Monitor 2.0, you need to upgrade both your MySQL
Enterprise Service Manager and your MySQL Enterprise Monitor Agent on
each machine that you are monitoring.

To perform the update process you must use an `update' installer. This
ensures that your current configuration information is migrated to the
new version of MySQL Enterprise Service Manager.

Before you start the migration, shutdown your MySQL Enterprise Service
Manager and MySQL Enterprise Monitor Agent on each monitored host. Then
install the updated MySQL Enterprise Service Manager application to
migrate the configuration and data of the main application and
repository. Once the new MySQL Enterprise Service Manager is running,
you can start to update and migrate each agent.

For more information on upgrading your MySQL Enterprise Service
Manager, see *Note mem-upgrading-2.0-server::. For more information on
upgrading an MySQL Enterprise Monitor Agent, see *Note
mem-upgrading-2.0-agent::.


File: manual.info,  Node: mem-upgrading-2.0-server,  Next: mem-upgrading-2.0-agent,  Prev: mem-upgrading-2.0,  Up: mem-upgrading-2.0

15.3.6.3 Upgrading to MySQL Enterprise Service Manager 2.0
..........................................................

Upgrading MySQL Enterprise Service Manager requires you to use on of the
_update_ installers. The update installer performs a number of
operations during installation:

   * A new database, required to support 2.0 functionality, is created.

   * You core dashboard, user, and rule information is migrated from
     the old database to the new database.

   * The core configuration parameters for the MySQL Enterprise Service
     Manager are migrated from MySQL Enterprise Monitor 1.3 are
     migrated to MySQL Enterprise Monitor 2.0.

The installation of the new software using the update installer follows
this basic sequence:

  1. Request the installation language.

  2. Confirm the location of the current MySQL Enterprise Service
     Manager installation.

  3. Specify whether you want to keep a copy of the old server,
     application, and database files.

  4. Configure the Tomcat server settings, including whether the new
     server should support SSL connections from agents.

  5. If requested, the application and database information is backed
     up and upgraded, before the new application is installed.

The installation process is consistent for all platforms. A sample of
the process for Max OS X has been provided below:

  1. Double click on the update installer. The update installer will
     have `update' in the file name. For example,
     `mysqlmonitor-2.0.0.7101-osx-update-installer.app'.

  2. Confirm the language you want to use when installing the software.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Server Update:
     Language Selection

     Click `OK'

  3. You will be presented with an information screen showing the
     application you are installing. Click `Next' to continue.

  4. Specify, or locate, the previous installation of MySQL Enterprise
     Service Manager If you installed the server within the default
     location, the current version of the application should be located
     automatically.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Server Update:
     Previous Installation

  5. The installer can keep a backup copy of your existing application,
     including keeping a complete backup of the data stored within your
     MySQL Enterprise Monitor repository database.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Server Update: Backup
     of Previous Installation

     Specify the location of the backup (default is to use the `backup'
     directory within your installation directory). Note that backing
     up the database in addition to the main application will increase
     the installation time as the files have to be copied. The larger
     the size of your repository data, the longer the installation
     process will take.

  6. Specify the Tomcat Server options. The Tomcat Server Port is the
     default port you will use to access the MySQL Enterprise
     Dashboard. If you want to support agents using SSL to communicate
     to MySQL Enterprise Service Manager, you must check the `Is SSL
     support required?'

  7. Confirm that you want to continue the installation. Once
     installation has started, the backup of you existing application
     (and database) will start, although the process may take some
     time. Wait until the process completes.

  8. Once the process has completed you will be provided with a
     notification of the installation process, including how to
     uninstall the application if you want to do so in the future. If
     any errors occurred, they will be reported here.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Server Update:
     Completed installing files

  9. The installation has now completed. You can automatically start
     the MySQL Enterprise Service Manager and view the attached Readme
     file by ensuring the checkboxes on this page are selected.

 10. You can now quit the installer.

Once the installation has completed, the first time you login to MySQL
Enterprise Dashboard you will be asked to provide your login
credentials, if they do not already exist in the server configuration,
or to provide a copy of the Advisor jar suitable for your MySQL
Enterprise Service Manager version.

FIGURE GOES HERE: MySQL Enterprise Monitor: Server Update: Final Setup

MySQL Enterprise Monitor has now been updated. You must update each of
your agents to MySQL Enterprise Monitor Agent 2.0 to ensure that they
are providing the correct information to MySQL Enterprise Service
Manager


File: manual.info,  Node: mem-upgrading-2.0-agent,  Prev: mem-upgrading-2.0-server,  Up: mem-upgrading-2.0

15.3.6.4 Upgrading to MySQL Enterprise Monitor Agent 2.0
........................................................

To upgrade an agent you should use a `update' installer. This will
migrate your configuration information, simplifying the upgrade process
significantly.

*Note*:

The agent log file, `mysql-service-agent.log', if it exists, will be
retained during the upgrade. A new log file, `mysql-monitor-agent.log'
is used by MySQL Enterprise Monitor Agent 2.0.

The core sequence is the same on all platforms, the update process on
Linux is shown below:

  1. Start the update installer.

          shell> ./mysqlmonitoragent-2.0.0.7101-linux-glibc2.3-x86-32bit-update-installer.bin

  2. Set the language for the installation process.

          Language Selection

          Please select the installation language
          [1] English
          [2] Japanese
          Please choose an option [1] :

  3. Confirm or update the location of the installation directory of
     the previous version.

          ----------------------------------------------------------------------------
          Welcome to the setup wizard for the MySQL Enterprise Monitor Agent Update

          ----------------------------------------------------------------------------
          Please specify the directory that contains the previous installation of
          the MySQL Enterprise Monitor Agent

          Installation directory [/opt/mysql/enterprise/agent]:

  4. Specify whether you want to create a backup of the current
     application and configuration information, and if so, where the
     backup directory should be created.

          ----------------------------------------------------------------------------
          Current installation backup

          Do you want to create a backup during the update process?

          Backup the current installation [Y/n]: Y

          Backup directory [/opt/mysql/enterprise/agent/patchbackup]:

  5. You will be asked whether you want to enable the Query Analyzer.
     The Query Analyzer enables you to monitor the execution
     stateistics for individual queries executed through your MySQL
     servers. To enable, you must specify the proxy port, MySQL server
     and MySQL server port that you want to use. If you do not enable
     Query Analyzer now, you can enable it later. See *Note
     mem-query-analysis::.

          ----------------------------------------------------------------------------
          Query Analysis Configuration

          MySQL Proxy enables query monitoring and analysis by listening on the port
          specified below for client connections that are then passed through to a
          backend MySQL database server. It is not needed for basic monitoring
          functionality, but is required for query monitoring and analysis.

          Visit the following URL for more information:
          https://enterprise.mysql.com/docs/monitor/2.0/en/mem-query-analysis.html

          Enable Proxy (recommended) [Y/n]:

          Proxy Port [4040]:

          Backend Host: 127.0.0.1   (cannot be changed)

          Backend Port: 3306   (cannot be changed)

  6. You are now ready to complete the installation. Confirm that you
     want to continue.

          ----------------------------------------------------------------------------
          Setup is now ready to begin installing MySQL Enterprise Monitor Agent Update on your computer.

          Do you want to continue? [Y/n]:

          ----------------------------------------------------------------------------
          Please wait while Setup installs MySQL Enterprise Monitor Agent Update on your computer.

           Installing
           0% ______________ 50% ______________ 100%
           #########################################

          ----------------------------------------------------------------------------
          Setup has finished installing MySQL Enterprise Monitor Agent Update on your computer.

          Restart MySQL Enterprise Monitor Agent now [Y/n]:

          View Readme File [Y/n]: n

Before connecting your MySQL Enterprise Monitor Agent to your MySQL
server you must update the grants for the MySQL Enterprise Monitor
Agent. Connect to the MySQL server and run this statement to update the
required grants:

     GRANT CREATE, INSERT
       ON mysql.*
       TO  'MYSQLUSER'@'LOCALHOST'
       IDENTIFIED BY 'AGENT_PASSWORD';

Replacing the `mysqluser' and `agent_password' parameters with the
values used for connecting your agent to your MySQL server.

Once the update agent has communicated with the MySQL Enterprise
Service Manager the core information about the agent and the MySQL
server it is monitoring will be migrated to the new data format
required by MySQL Enterprise Service Manager 2.0. To migrate the
existing stored data, see *Note mem-deployment-migration-2-0::.


File: manual.info,  Node: mem-unattended-update,  Prev: mem-upgrading-2.0,  Up: mem-upgrading

15.3.6.5 Unattended MySQL Enterprise Monitor Update
...................................................

The options available when performing an unattended MySQL Enterprise
Service Manager update are as follows:

     --help                         Display the list of valid options

     --version                      Display product information

     --optionfile <optionfile>      Installation option file
                                    Default:

     --mode <mode>                  Installation mode
                                    (Windows)Default: win32
                                    (Unix)Default: gtk
                                    (Mac OS X)Default: osx
                                    (Windows)Allowed: win32 unattended
                                    (Unix)Allowed: gtk text xwindow unattended
                                    (Mac OS X)Allowed: osx text unattended

     --debugtrace <debugtrace>      Debug filename
                                    Default:

     --installer-language <installer-language> Language selection
                                     Default:
                                     Allowed: en  jp

     --installdir <installdir>      Previous Installation
                                    Default:

     --createDataBackup <createDataBackup>

                                    Default: 1

     --backupDir <backupDir>        Backup directory
                                    Default:

The options for an unattended update of the agent differ only in that
the `createDataBackup' option is replaced by `createBackup'.

If you did not install the MySQL Enterprise Service Manager to the
default directory the `installdir' option must be specified. `mode'
must also be specified when performing an unattended update. Otherwise,
performing an unattended update is identical to the process described in
*Note mem-unattended-installation::.


File: manual.info,  Node: mem-reinstalling-mysqlmonitor,  Next: mem-changing-installation,  Prev: mem-upgrading,  Up: mem-upgradeorchange

15.3.6.6 Reinstalling MySQL Enterprise Monitor
..............................................

In some cases you may want to reinstall MySQL Enterprise Monitor rather
than updating your current installation. To reinstall rather than
update MySQL Enterprise Monitor follow these steps:

  1. Stop all the Monitor Agents

  2. Run the `uninstall' programs for both the MySQL Enterprise Service
     Manager and the MySQL Enterprise Monitor Agent

  3. Begin the new installation

To stop the Monitor Agents see:

   * Windows - *Note mem-starting-agent-windows::

   * Unix - *Note mem-starting-agent-unix::

   * Mac OS X - *Note mem-starting-agent-osx::

Instructions for removing the MySQL Enterprise Service Manager and the
MySQL Enterprise Monitor Agent are given in *Note mem-uninstall::.


File: manual.info,  Node: mem-changing-installation,  Prev: mem-reinstalling-mysqlmonitor,  Up: mem-upgradeorchange

15.3.6.7 Changing Your MySQL Enterprise Monitor Installation
............................................................

* Menu:

* mem-ungrading-monitored-server::  Upgrading the Monitored MySQL Server
* mem-changing-monitored-server::  Changing the Server That an Agent Monitors
* mem-suspending-agent::         Temporarily Suspending the Agent

This section describes the best practices to employ when changing your
MySQL Enterprise Monitor installation.


File: manual.info,  Node: mem-ungrading-monitored-server,  Next: mem-changing-monitored-server,  Prev: mem-changing-installation,  Up: mem-changing-installation

15.3.6.8 Upgrading the Monitored MySQL Server
.............................................

When upgrading a monitored MySQL server first stop the agent. To stop
the agent see:

   * Windows - *Note mem-starting-agent-windows::

   * Unix - *Note mem-starting-agent-unix::

   * Mac OS X - *Note mem-starting-agent-osx::

Stop the MySQL server and perform the upgrade. For instructions on
stopping and restarting the MySQL service under Windows see *Note
mem-server-starting-windows::.

To stop and restart the MySQL daemon under Unix and Mac OS X, see,
*Note mem-server-starting-unix-osx::.

Once the service/daemon is stopped you may upgrade your server.  For
instructions on upgrading your MySQL server see the reference manual
pertaining to your server version. When the upgrade is complete restart
the MySQL server.

*Note*:

The agent's log file will show that the server was down.


File: manual.info,  Node: mem-changing-monitored-server,  Next: mem-suspending-agent,  Prev: mem-ungrading-monitored-server,  Up: mem-changing-installation

15.3.6.9 Changing the Server That an Agent Monitors
...................................................

You need not reinstall the MySQL Enterprise Monitor Agent in order to
change the MySQL server that it monitors. It is possible to adapt an
existing agent so that it monitors a different server.

To do this you must stop the service agent and then remove the server
that it is monitoring. To stop the agent see:

   * Windows - *Note mem-starting-agent-windows::

   * Unix - *Note mem-starting-agent-unix::

   * Mac OS X- *Note mem-starting-agent-osx::

For instructions on removing a server see, *Note
mem-deleting-mysql-server::.

Once the agent is stopped and the server is removed from the Dashboard,
changes may be made to the `mysql-monitor-agent.ini', or the
`agent-instance.ini' file within the agent `instances' instances
directory. You can find the location of the directory by examining the
content of the `mysql-monitor-agent.ini' and checking the value of the
`mysqld-instance-dir' parameter.

If you want to make changes to the monitored MySQL server, edit the
`agent-instance.ini' file. Change the `user', `password', `hostname',
and `port' values if required. For more information, see *Note
mem-cfg-agent-ini::.

To change other settings, such as enabling proxy support (required for
Query Analyzer), the management host, or the port number used by the
agent, modify the `mysql-monitor-agent.ini' file. For more information,
see *Note mem-cfg-mysql-monitor-agent-ini::.

To restart the agent see:

   * Windows - *Note mem-starting-agent-windows::

   * Unix - *Note mem-starting-agent-unix::

   * Mac OS X- *Note mem-starting-agent-osx::

*Note*:

If you are adapting an existing agent to monitor a remote server make
sure that the agent has the credentials for remote access and that the
port on the remote MySQL server instance is open. For more information,
see *Note mem-install-agent-remote::.

If you experience difficulties starting the agent, check *Note
mem-troubleshooting-agent-start::.

Log in to the Dashboard and you should find your new server in the `All
Servers' group.


File: manual.info,  Node: mem-suspending-agent,  Prev: mem-changing-monitored-server,  Up: mem-changing-installation

15.3.6.10 Temporarily Suspending the Agent
..........................................

In some situations you may need to bring down a monitored server. When
this is necessary, it is good practice to stop the agent first--doing
so will avoid generating a `Server is unreachable' event.

For instance, suppose you need to stop the server in order to do a
backup. The steps to follow are:

  1. Stop the agent

  2. Stop the service/daemon

  3. Perform the backup

  4. Restart the service/daemon

  5. Restart the agent

To stop or start the agent see:

   * Windows - see *Note mem-starting-agent-windows::

   * Unix - see *Note mem-starting-agent-unix::

   * Mac OS X - see *Note mem-starting-agent-osx::

To stop the MySQL service/daemon see the MySQL reference manual for
your server version. You can find the manual online at
`http://dev.mysql.com/doc/refman'.

Follow these steps and there will be no `noise' associated with backing
up your server. In contrast, if you leave the agent running while
bringing down the server, you will generate a `Server is unreachable'
event.

As an alternative to stopping the agent, you can change the logic
associated with a rule. For instance, you could alter the threshold of
the rule `Server is unreachable':

     %server.reachable% == THRESHOLD

to:

     %server.reachable% == THRESHOLD  && CURTIME() NOT BETWEEN '22:00:00' AND '23:00:00'

This would effectively blackout the rule between 10 and 11 pm, during
which time you could perform a backup.

For more information about editing rules see *Note
mem-editing-built-in-rules::. To blackout all events associated with a
specific server or group of servers see *Note mem-advisor-blackouts::.


File: manual.info,  Node: mem-uninstall,  Prev: mem-upgradeorchange,  Up: mem-install

15.3.7 Uninstalling the MySQL Enterprise Monitor
------------------------------------------------

* Menu:

* mem-windows-removal::          Removing the MySQL Enterprise Monitor: Windows
* mem-unix-osx-removal::         Removing the MySQL Enterprise Monitor: Unix and Mac OS X

Removal of the MySQL Enterprise Monitor requires removal of the MySQL
Enterprise Service Manager and the MySQL Enterprise Monitor Agent
Service. In some circumstances, when running multiple agents on one
machine for instance, you may not want to remove the entire MySQL
Enterprise Monitor Agent Service but only a single monitored server.


File: manual.info,  Node: mem-windows-removal,  Next: mem-unix-osx-removal,  Prev: mem-uninstall,  Up: mem-uninstall

15.3.7.1 Removing the MySQL Enterprise Monitor: Windows
.......................................................

* Menu:

* mem-remove-windows::           Removing the MySQL Enterprise Service Manager
* mem-removing-agent-windows::   Removing the Monitor Agent


File: manual.info,  Node: mem-remove-windows,  Next: mem-removing-agent-windows,  Prev: mem-windows-removal,  Up: mem-windows-removal

15.3.7.2 Removing the MySQL Enterprise Service Manager
......................................................

* Menu:

* mem-remove-windows-services::  Removing MySQL Enterprise Monitor Services Only

Remove the MySQL Enterprise Service Manager by going to the `Control
Panel' and choosing `Add or Remove Programs'. Find the entry for `MySQL
Enterprise Monitoring and Advisory Service' and remove it. During the
uninstall process you will be given the option of saving existing data
and log files. Choose this option if you plan to reinstall the MySQL
Enterprise Monitor.

If you are not saving existing data, after MySQL Enterprise Service
Manager has been removed you may delete the `C:\Program
Files\MySQL\Enterprise\Monitor' directory.

*Warning*:

If you chose not to remove existing data and log files when
uninstalling MySQL Enterprise Service Manager do *not* remove the
`C:\Program Files\MySQL\Enterprise\Monitor' directory. Doing so will
delete these files.

If you added the Tomcat/Apache web server to the list of Windows
firewall exceptions, remove this service by opening the `Windows
Firewall' from the `Control Panel'. Choose the `Exceptions' tab and
delete the `Tomcat/Apache' entry.


File: manual.info,  Node: mem-remove-windows-services,  Prev: mem-remove-windows,  Up: mem-remove-windows

15.3.7.3 Removing MySQL Enterprise Monitor Services Only
........................................................

When the MySQL Enterprise Service Manager is installed, the
Tomcat/Apache and MySQL server services are started. It is possible to
remove these services without also removing your MySQL Enterprise
Service Manager installation. (For more information about these
services see, *Note mem-server-starting-windows:: or, *Note
mem-server-starting-unix-osx::.)

Do this by finding the `MySQL Enterprise Monitor' menu option and
choosing `Services' and then `Uninstall MySQL Enterprise Monitor
Services'. This will remove all the services associated with MySQL
Enterprise Service Manager.

You can confirm that these services have been removed by checking
services in the Microsoft Management Console Services window.

If you wish to reinstall these services you can do this by using the
`Install MySQL Enterprise Monitor Services' menu option.

It is also possible to remove services using the `mysqlmonitorctl.bat'
file found in the `C:\Program Files\MySQL\Enterprise\Monitor'
directory. To see the available options, go to the command line and
type: myqlnetworkctrl help.  This batch file is discussed in more
detail in *Note mem-server-starting-windows::.


File: manual.info,  Node: mem-removing-agent-windows,  Prev: mem-remove-windows,  Up: mem-windows-removal

15.3.7.4 Removing the Monitor Agent
...................................

* Menu:

* mem-remove-single-agent-windows::  Removing a Single Agent

To remove the Monitor Agent itself, open the `Control Panel' and choose
`Add or Remove Programs'. Find the entry for `MySQL Enterprise Monitor
Agent' and remove it. This will execute the uninstall program located
in the `C:\Program Files\MySQL\MySQL\Enterprise\Agent' directory.

*Warning*:

If you are running more than one agent on the same machine and wish to
remove only one of the agents, do *not* remove the `MySQL Enterprise
Monitor Agent' entry from the `Add or Remove Programs' menu. To remove
a single agent see *Note mem-remove-single-agent-windows::.

After removing the Monitor Agent you may also need to remove the
directories, `C:\Program Files\MySQL\Enterprise' and `C:\Program
Files\MySQL\Enterprise\Agent'.

Removing the Monitor Agent in this fashion will remove the default
service. However, if you are running additional Monitor Agents as
described in *Note mem-cfg-agent-ini::, you will have to remove those
agents manually. See the next section for instructions on doing this.


File: manual.info,  Node: mem-remove-single-agent-windows,  Prev: mem-removing-agent-windows,  Up: mem-removing-agent-windows

15.3.7.5 Removing a Single Agent
................................

If you are running more than one agent on the same machine and wish to
remove only one of the agents, do *not* remove the `MySQL Enterprise
Monitor Agent' entry from the `Add or Remove Programs' menu. To remove
a single agent and leave other agents intact follow these steps:

  1. Stop the agent

  2. Confirm the location of the log files

  3. Remove the agent as a service

  4. Remove/Archive the associated files

It is best to stop the agent before removing it; for instructions on
stopping an agent see, *Note mem-starting-agent-windows::.

You can confirm the location of the agent log files by checking the
`ini' file. For more information on this topic see *Note
mem-cfg-mysql-monitor-agent-ini::.

Go to the command line and remove the MySQL Enterprise Monitor Agent as
a Windows service by typing:

     shell> sc delete AGENTNAME

You can confirm that the agent has been removed by checking the
Microsoft Management Console Services window. There should no longer be
an entry for the removed agent.

You should also remove or archive any log or configuration files
associated with this agent. If you have installed any additional
agents, remove them in the same fashion.


File: manual.info,  Node: mem-unix-osx-removal,  Prev: mem-windows-removal,  Up: mem-uninstall

15.3.7.6 Removing the MySQL Enterprise Monitor: Unix and Mac OS X
.................................................................

* Menu:

* mem-remove-unix-osx::          Removing the MySQL Enterprise Service Manager
* mem-removing-service-agent-unix-osx::  Removing the Monitor Agent


File: manual.info,  Node: mem-remove-unix-osx,  Next: mem-removing-service-agent-unix-osx,  Prev: mem-unix-osx-removal,  Up: mem-unix-osx-removal

15.3.7.7 Removing the MySQL Enterprise Service Manager
......................................................

To remove the MySQL Enterprise Service Manager, find the `uninstall'
file in the `/opt/mysql/enterprise/monitor' directory.

Execute this file by typing:

     shell> ./uninstall

During the uninstall process you will be given the option of saving
existing data and log files. Choose this option if you plan to
reinstall the MySQL Enterprise Monitor.

If you are not saving existing data, after uninstalling the MySQL
Enterprise Service Manager you may remove the
`/opt/mysql/enterprise/monitor' directory.

*Warning*:

If you chose not to remove existing data and log files when
uninstalling the MySQL Enterprise Monitor do *not* remove the
`/opt/mysql/enterprise/monitor' directory; doing so will delete these
files.

On Red Hat Enterprise Linux 4 and Fedora Core 4, the uninstall script
may not stop the Tomcat server. Do this manually if necessary. To do
this see, *Note mem-server-starting-unix-osx::.

There may be other Java processes running on your system. Be careful
not to accidentally stop them.


File: manual.info,  Node: mem-removing-service-agent-unix-osx,  Prev: mem-remove-unix-osx,  Up: mem-unix-osx-removal

15.3.7.8 Removing the Monitor Agent
...................................

* Menu:

* mem-remove-agent-unix-osx::    Removing a Single Agent

Prior to removal of the Monitor Agent Service you should stop any
agents. Do this by changing to the `init.d' directory and issuing the
command, `./mysql-monitor-agent stop'.

You will find the `uninstall' file in the `/opt/mysql/enterprise/agent'
directory under Unix and in the `/Applications/mysql/enterprise/agent'
directory on Mac OS X. Execute this file by navigating to this
directory and typing:

     shell> ./uninstall

After uninstalling the Monitor Agent you may remove the
`/opt/mysql/enterprise/agent' directory.  Under Mac OS X this directory
is called `/Applications/mysql/enterprise/agent'.

Removing the Monitor Agent in this fashion will remove the default
service, and all the configuration files for different instances.


File: manual.info,  Node: mem-remove-agent-unix-osx,  Prev: mem-removing-service-agent-unix-osx,  Up: mem-removing-service-agent-unix-osx

15.3.7.9 Removing a Single Agent
................................

If you are running more than one agent on the same machine and wish to
remove only one of the agents, do *not* run the uninstall program. To
remove a single agent and leave other agents intact follow these steps:

  1. Stop the agent

  2. Confirm the location of the log files

  3. Remove the agent as a service

  4. Remove/Archive associated files

It is best to stop the agent before removing it; for instructions on
stopping an agent see:

   * Unix - *Note mem-starting-agent-unix::

   * Mac OS X - *Note mem-starting-agent-osx::

You can confirm the location of the agent log files by checking the
`ini' file. For more information on this topic see *Note
mem-cfg-mysql-monitor-agent-ini::.

You may then remove the agent as a daemon by removing its entry in the
`init.d' directory. You should also remove or archive any log or
configuration files associated with this agent.

If you have installed any additional agents, remove them in the same
fashion.


File: manual.info,  Node: mem-deployment,  Next: mem-dashboard,  Prev: mem-install,  Up: mem-introduction

15.4 Deploying MySQL Enterprise Service Manager
===============================================

* Menu:

* mem-deployment-backup::        Backing up MySQL Enterprise Service Manager
* mem-deployment-migration-2-0::  Migrating 1.3.x Historical Data to MySQL Enterprise Monitor 2.0
* mem-deployment-maintenance::   Regular MySQL Enterprise Monitor Maintenance
* mem-deployment-config::        Choosing Suitable MySQL Enterprise Service Manager Hardware Configurations

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

This chapter provides some notes and guidance on deploying MySQL
Enterprise Service Manager, including hardware and server requirements
for the MySQL Enterprise Service Manager, and how to backup the
monitoring data.


File: manual.info,  Node: mem-deployment-backup,  Next: mem-deployment-migration-2-0,  Prev: mem-deployment,  Up: mem-deployment

15.4.1 Backing up MySQL Enterprise Service Manager
--------------------------------------------------

If you want to backup the data stored within your MySQL Enterprise
Service Manager, you can use any of the typical backup solutions, such
as `mysqldump', to save your data. All you need to backup the
information is host name, user name and password details that were set
during the installation of the MySQL Enterprise Service Manager

You can locate this information by examining the contents of the
`configuration_report.txt' file that was generated when MySQL
Enterprise Service Manager was installed. A scample of the file is
provided below:

     MySQL Enterprise Monitor (Version 2.0.0.7088 : 20081031_152749_r7088)
     Here are the settings you specified:
     Application hostname and port: http://127.0.0.1:18080
     Tomcat Ports: 18080 - 18443 (SSL)
     MySQL Port : 13306
     Repository Credentials (bundled MySQL):
     ---------------------------------------
     service_manager/Password
     Use the following command to login to the MySQL Enterprise Monitor database:
     mysql -uservice_manager -pPassword -P13306 -h127.0.0.1

The last line provides the information about how to connect to the
server using the standard *Note `mysql': mysql. command line client.

All the MySQL Enterprise Monitor repository information, including your
configuration, rule and historical data is stored within the `mem'
database.

To backup this information using `mysqldump' you might use the
following command:

     shell> mysqldump --single-transaction »
     -uservice_manager -pPassword -P13306 -h127.0.0.1 mem >mem.dump

The above command would create a file, `mem.dump', containing all of
the MySQL Enterprise Monitor data.

To ensure consistency in a recovery situation, you may also want to
backup the agent configuration and metadata stored on each monitored
MySQL server. To do this:

   * Backup the configuration files of each agent. You should keep a
     copy of the `etc' directory for each agent. This directory
     contains the main configuration file, `mysql-monitor-agent.ini',
     and the configuration information for each server being monitored,
     which is stored within the `etc/instances' directory.

   * On each server being monitored, retain a copy of the
     `mysql.inventory' table, which contains the unique ID of the MySQL
     server.


File: manual.info,  Node: mem-deployment-migration-2-0,  Next: mem-deployment-maintenance,  Prev: mem-deployment-backup,  Up: mem-deployment

15.4.2 Migrating 1.3.x Historical Data to MySQL Enterprise Monitor 2.0
----------------------------------------------------------------------

You can migrate the data generated during a MySQL Enterprise Monitor
1.3.x installation using the Data Migration functionality of the
`Server Configuration' panel.

To use the data migration feature, you must have installed MySQL
Enterprise Service Manager using an _update_ installer.  The update
installer performs the initial migration of your configuration, rules,
schedule, and events data. The historical data is not migrated until
you explicitly request the migration of information within the `Manage
Servers' section of the `Settings' panel.

Data migration works on a single server, allowing you to select on
which servers you want to migrate information. The migration is subject
to the following:

   * You must elect to migrate the data from each server individually.

   * Migration takes approximately 5-6 hours, for each month, for each
     server. Therefore, if you have six months of data on 10 servers it
     could take between 300 and 360 hours (15 days) to migrate all of
     your historical data one server at a time.

   * To limit the data migration, set the `Data Purge Behavior' within
     the `Settings' page. Only data more recent than the specified
     purge period will be migrated. Data older than the purge period
     will be ignored.

   * To prevent performance issues, migrate only one or a small number
     of servers concurrently.

   * You can start and stop the migration of the data at any time.  As
     a general guide, you should avoid stopping the data migration
     process and allow it to complete unless:

        * Run out of disk space.

        * MySQL Enterprise Service Manager becomes too slow and
          unresponsive.

        * Migration never completes.

     With the last item, where the migration never completes,
     occasionally there are some aspects of the data that cannot be
     migrated successfully. This will prevent the migration process
     completing, but does not affect the conversion of any data that
     could be migrated.

*Starting Historical Data Migration*

To start data migration:

   * Switch to the `Manage Servers' display of the `Settings' panel
     within MySQL Enterprise Dashboard.

   * Ensure that the data migration functionality has been enabled.
     The `Start' and `Stop' buttons next to `Historical Data Migration'
     will be visible.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Historical Data
     Migration Availability

   * Select the servers you want to migrate by using the checkbox next
     to each server name. You can select one or more servers to
     migrate. Servers that are suitable for migration will show their
     migration status within the `Migration Status' columnn. If the
     server is not able to be migrated, `N/A' will be shown.

   * Click `Start' next to `Historical Data Migration'.

   * You will be presented with a confirmation dialog box. To start the
     migration, click `start migration'.  To cancel migration, click
     `cancel'.

   * The servers that have been selected for migration will show
     `Queued for Migration' in the `Migration Status' column.

     FIGURE GOES HERE: MySQL Enterprise Monitor: Confirming Historical
     Data Migration

*Monitoring Historical Data Migration*

You can check the migration status of any individual server by
examining the `Migration Status' column for each server. You can see an
example of the migration status below.

FIGURE GOES HERE: MySQL Enterprise Monitor: Historical Data Migration
Progress

Note that the migration status is shown according to the state of
migration at the time the page was loaded. The actual migration
continues in the background, and the current state may not match the
state of the migration at the time it is viewed.

Servers showing `Done' in the `Migration Status' column have already
completed their migration.

You can check the overall migration status by examining the `Upgrade
Status' display.

*Stopping Historical Data Migration*

You can stop the migration process for any server that is still
migrating data. The migration can be restarted at any time without
causing any problems.

To stop the historical data migration:

  1. Select the servers you want to stop migrating by using the
     checkbox next to each server name. You can select one or more
     servers to stop migrating.

  2. Click `Stop' next to `Historical Data Migration'.

Confirmation that the migration has been stopped will be provided.  If
migration has already completed, you will be notified.

*Removing Old Data*

Once data migration has been completed for all the servers you want to
migrate, you may want to delete or remove access to the old data within
your MySQL Enterprise Monitor repository. Data for MySQL Enterprise
Monitor 1.3 was stored in a database called `merlin' within the MySQL
repository. Data for MySQL Enterprise Monitor 2.0 is stored within a
database called `mem'.

To create a backup of the old information, use *Note `mysqldump':
mysqldump.:

     shell> mysqldump -uservice_manager -pPassword -P13306 -h127.0.0.1 merlin >data-1.3.sql

The above will create a file, `data-1.3.sql' containg all of the MySQL
Enterprise Monitor 1.3 information.

If you remove access to the old data, then the data migration options
for old servers will be removed from the `Manage Servers' panel within
MySQL Enterprise Service Manager. To remove access, you need to
`REVOKE' access to the `merlin' database:

     mysql& REVOKE ALL on merlin.* FROM 'service_manager';

Note that revoking access to the old data will not reclaim any of the
disk space used by the old data.

To delete the data from the database and free up the space being used
by the historical information, `DROP' the `merlin' database:

     mysql& DROP DATABASE merlin;

Once all the data has been migrated you can hide the migration user
interface by clicking on the `hide migration interface' button.


File: manual.info,  Node: mem-deployment-maintenance,  Next: mem-deployment-config,  Prev: mem-deployment-migration-2-0,  Up: mem-deployment

15.4.3 Regular MySQL Enterprise Monitor Maintenance
---------------------------------------------------

MySQL Enterprise Monitor is generally self managing and does not need
excessive maintenance. You should, however, be aware of certain
maintentnace tasks that you can automate or will need to manually
perform to keep your MySQL Enterprise Monitor running efficiently.

   * Make sure you have set the purge interval for your data to an
     appropriate value according to durationa nd history of data that
     you want to keep. For more information, see *Note mem-data-purge::.

   * Check, and delete, the contents of the temporary directory with
     your MySQL Enterprise Service Manager installation directory.


File: manual.info,  Node: mem-deployment-config,  Prev: mem-deployment-maintenance,  Up: mem-deployment

15.4.4 Choosing Suitable MySQL Enterprise Service Manager Hardware Configurations
---------------------------------------------------------------------------------

Running MySQL Enterprise Service Manager places a reasonable load on
your system, and this load increases linearly as you add more agents
monitoring more servers. Ideally, you should use a dedicated machine for
MySQL Enterprise Service Manager, rather than running it alongside other
applications and services.

*Minimum System Requirements*

   * 2 or more CPU cores

   * 2 or more GB of RAM

   * Disk I/O subsystem applicable for a write-intensive database

*Recommended System Requirements (if monitoring 100 or more MySQL
servers)*

   * 4 or more CPU cores

   * 8 or more GB of RAM

   * Disk I/O subsystem applicable for a write-intensive database
     (RAID10, RAID 0+1)


File: manual.info,  Node: mem-dashboard,  Next: mem-dashboard-settings,  Prev: mem-deployment,  Up: mem-introduction

15.5 MySQL Enterprise Dashboard
===============================

* Menu:

* mem-server-tree::              The Server Tree
* mem-monitor-page-graphs::      The Server Graphs and Critical Events
* mem-heat-chart::               The Heat Chart

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

The purpose of the MySQL Enterprise Dashboard is to provide you with
information about your MySQL servers. It provides a list of the latest
MySQL Enterprise Advisor reports, server status information, MySQL
Enterprise alerts, and updated views of monitored MySQL servers. The
`Monitor' screen gives a quick overview of the status of your MySQL
servers.

Open the Dashboard by typing the host name into the address bar of your
web browser. If you are unsure of the host name check the `Application
host name and port' in the `configuration_report.txt' file. The default
value is `http://127.0.0.1:18080/Auth.action' but this login is only
valid if you are logging in from the machine that hosts the dashboard.
If you are logging in from a remote machine you will have to specify a
value other than `127.0.0.1'. Likewise, choose a different port if you
are not using the default. After logging in, select the `Monitor' tab.

The Monitoring page provides an instant health check for all of the
MySQL servers across the enterprise.

From this page users can:

   * View monitoring data and all critical MySQL Advisor Rule
     violations for all or selected servers.

   * Close and annotate MySQL Advisor Rule violations.

   * Quickly determine if there is a Monitor Agent that is not
     communicating with the Service Manager.

   * Quickly determine if there is a server that is in trouble or
     completely down.

   * View indicator value graphs for key MySQL and operating system
     (OS) level metrics. Graph presentation will default to a thumbnail
     view but will open into a larger image upon being clicked.

The monitored server or servers are displayed in a tab on the left
known as the `Server Tree'. You can navigate to a number pages that
provide more detailed information. These pages include:

   * `Monitor' -- the overview page providing you with a quick summary
     of the servers, their status, events, availability and load. The
     remainder of this chapter details the contents of this page.

   * `Advisors' -- shows the various advisors configured in your
     installation and allows you to schedule their execution on
     different servers, apply and manage rules and manage the advisor
     installation itself. For more information, see *Note
     mem-advisors::.

   * `Events' -- provides an interface into the event system that
     highlights specific issues and problems on your monitored servers.
     For more information on using Events, see *Note mem-events::.

   * `Query Analyzer' -- interfaces to the query monitoring system that
     can be used to monitor and track the individual queries that are
     being executed on a system and help to highlight problem queries
     that may need optimization or that may be affecting server load.
     For more information, see *Note mem-query-analysis::.

   * `Graphs' -- enables you to view and configure a number of
     individual graphcs covering a range of different statistics. For
     more details on how to view and use these graphs, see *Note
     mem-graphs::.

   * `Replication' -- provides information on the status and structure
     of your servers that are using replication. This page is only
     available if you have a suitable subscription level. For more
     information, see *Note mem-replication::.

   * `Settings' -- controls the settings for the server, including
     email configuration, passwords, and server and user management.
     For more information, see *Note mem-dashboard-settings::.

Graphs are shown in the center of the page beneath the tabs. If
applicable, you'll also find a list of critical events.

On the right is the color-coded `Heat Chart', showing the advisors that
are installed by default. The `Heat Chart' shows the most important
advisors, allowing a quick overview of the state of your servers. You
may open the `Heat Chart' in its own window by clicking the `Standalone
Heat Chart' link. If applicable, you'll also find a list of critical
events.

The `Show/Hide Legend' link toggles display of the key to the icons
used in the `Heat Chart'.

*Note*:

Find colorblind-accessible icons in the `alternate' directory. On Linux
this directory is immediately below the
`/monitor/apache-tomcat/webapps/ROOT/web/resources/images/' directory.
These images are stored in the same directory on Windows. To use them,
backup the originals and then copy and paste the alternate set into the
`images' directory.

If a specific server is selected in the `Server Tree' details about
this server are shown beneath the legend in the `Meta Info' area. The
information shown in this area is the host name, the MySQL version
number, the number of scheduled rules, the operating system, and the
CPU.

The `Meta Info' section also shows how long the agent has been running,
when it last contacted the MySQL server it is monitoring, and the last
time the agent contacted the dashboard.  Mouse over the date shown
beside `Up Since' and a pop-up box displays the time that has elapsed
since the server instance was last started. You can also mouse over the
`Last MySQL Contact' and the `Last Agent Contact' dates.

*Note*:

In the case of remote monitoring, the agent runs on a different machine
than the MySQL server that it is monitoring. The `Hostname', `MySQL',
and `Rules' information applies to the system being monitored. The `OS'
and `CPU' information applies to the machine on which the agent is
running.  For more information about remote monitoring see, *Note
mem-install-agent-remote::.

The top of the screen shows the refresh cycle and `Help' and `Log Out'
links. Click the `Help' link to open the documentation in a separate
browser window. Choose `Log Out' if you wish to leave the Dashboard or
to log in as a different user.  Different refresh rates are available
from the drop-down listbox.

In the footer are external links to MySQL Enterprise and information
about the current user. Users can remain connected to the Dashboard and
update their subscription, use the Enterprise Knowledge Base, and
contact technical support. Your subscription information is also
displayed here, showing the number of days remaining and the number of
licenses. The number of licenses indicates to the number of machines
that may be monitored; any number of MySQL servers may be running on a
specific machine.

The footer also contains a link to the `Settings' page. If your
subscription is current it reads `Subscription is up-to-date. More
info....'. For more information about the `Settings' page see *Note
mem-product-info::.


File: manual.info,  Node: mem-server-tree,  Next: mem-monitor-page-graphs,  Prev: mem-dashboard,  Up: mem-dashboard

15.5.1 The Server Tree
----------------------

The tab on the left displays the Server tree. By default the first
group of servers is selected. This selection determines the information
shown on the `Monitor' page.

If a server group is selected, the information presented on the
`Monitor' page is aggregate information for this group; if only one
server is selected the information applies to that server only.

Change your server selection and the information shown in the graphs
and in the `Heat Chart' changes.

*Note*:

For more information about server groups see, *Note
mem-server-grouping::.

The individual server, or server group, selected in the Server Tree
also determines what information appears when the `Advisors' tab or the
`Events' tab is selected.

The Server Tree presents an easy way to navigate to different groups or
to specific servers.


File: manual.info,  Node: mem-monitor-page-graphs,  Next: mem-heat-chart,  Prev: mem-server-tree,  Up: mem-dashboard

15.5.2 The Server Graphs and Critical Events
--------------------------------------------

The center of the `Monitor' page gives a visual representation of the
state of your servers.

FIGURE GOES HERE: MySQL Enterprise Dashboard: The Graphs screen

The graphs present information about the currently selected server or
server group. The default graphs show the hit ratios, CPU utilization,
connections, and database activity for a specific interval.

To set the interval click the `configure graphs' link immediately below
the graphs. This opens a dialog box where you can choose the default
interval for the x-axis of the graphs.  Defining a shorter or longer
interval gives you a shorter or longer term view of server activity.
The thumbnail and full-size graph dimensions can also be adjusted from
this dialog box. Save any changes that you have made and the values
chosen will be the defaults whenever you log in.

You can also choose the default graphs shown on the `Monitor' page. To
do this click the `edit favorites' link and choose the graphs you want
from the drop-down list box. To choose contiguous graphs, hold down the
`Shift' key and click on the desired graphs. For a non-contiguous
selection, click the desired graphs while holding down the `Ctrl' key.
The maximum number of graphs that can be displayed on the `Monitor'
page is six. Save your changes and these will be the default graphs
whenever you log in.

Color coding helps distinguish different aspects of each graph.  With
`Database Activity' for example, you can readily distinguish `SELECT'
statements from database insertions.

Clicking a graph opens a detailed view with `Graph Display' and
`Configure' tabs. Choose the `Configure' tab to temporarily change the
way that a graph displays. Changes made from this tab only apply to the
standalone graph while it is open. Persistent changes are made as
described above.

Dismiss the enlarged graph by clicking the `hide' button.

`Critical' alerts appear on this page immediately below the
graphs-quickly attracting your attention. For a description of all the
different alarm levels see, *Note mem-heat-chart::. This is the subject
of discussion in *Note mem-events::.


File: manual.info,  Node: mem-heat-chart,  Prev: mem-monitor-page-graphs,  Up: mem-dashboard

15.5.3 The Heat Chart
---------------------

The `Heat Chart' is found on the right side of the `Monitor' page and
shows the status of critical rules. Monitored servers are organized by
groups. To view the status of a specific server, click the `+' button
next to the appropriate server group.

Whenever a new agent contacts the Service Manager for the first time,
all the rules in the Heat Chart Advisor are automatically activated.
These Advisors monitor the status of the server and agent, critical
operating system indicators, and important events related to your MySQL
servers. An example follows.

FIGURE GOES HERE: MySQL Enterprise Dashboard: The Heat Chart

To interpret the Heat Chart see the following legend.

FIGURE GOES HERE: MySQL Enterprise Dashboard: The Heat Chart legend

The status `unknown' will typically apply when an agent is down and can
no longer report the status of the server that it is monitoring. The
status `unknown' may also apply if the data collection that should be
collected is not available on the server being monitored.

You may open the Heat Chart in its own browser window by clicking the
`Standalone Heat Chart' link immediately below the `Heat Chart' on the
left. If you like, the refresh rate can be set to a different rate than
the setting on the `Monitor' page.

In addition to showing the most important advisors, the `Heat Chart'
also has columns that display the number of critical, warning, and
informational alarms. Clicking the hyperlink in any one of these
columns takes you to the `Event' screen, which gives more detailed
information. For more information about events see, *Note mem-events::.

When the Dashboard is first installed no notification groups are
associated with the Advisors shown in the Heat Chart. For more
information on this topic see, *Note
mem-advisor-installation-after-login:: and, *Note
mem-notification-groups::.


File: manual.info,  Node: mem-dashboard-settings,  Next: mem-advisors,  Prev: mem-dashboard,  Up: mem-introduction

15.6 The Settings Page
======================

* Menu:

* mem-global-settings::          Global Settings
* mem-user-preferences::         User Preferences
* mem-managing-servers::         Manage Servers
* mem-managing-users::           Managing Users
* mem-notification-groups::      Manage Notification Groups
* mem-logs::                     Logs
* mem-product-info::             The Product Information Screen

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

Upon initial installation you may have configured your MySQL Enterprise
credentials and also outgoing email settings.  This section explores
the configuration settings in more detail, and also shows how to manage
servers, users, notification groups, Simple Network Management Protocol
(SNMP) traps, log files, and the product information screen.

Knowledge of server management is a prerequisite for properly
configuring advisors -- the subject of *Note mem-advisors::.

To get to the `Settings' page open the Dashboard and choose the
`Settings' tab.


File: manual.info,  Node: mem-global-settings,  Next: mem-user-preferences,  Prev: mem-dashboard-settings,  Up: mem-dashboard-settings

15.6.1 Global Settings
----------------------

The `Global Settings' control the main confirguration parameters for
the entire MySQL Enterprise Monitor system, including your email
notifications, data purge, and Enterprise website credentials.

FIGURE GOES HERE: MySQL Enterprise Dashboard: Settings

The `Global Settings' page is divided into a number of different
sections:

   * `Outgoing Email Settings'

     Configures the settings for email notificated by MySQL Enterprise
     Service Manager. You must configure the `From Address' `SMTP
     Server' settings.  If your server requires authorization, complete
     the necessary server login details, and whether SSL is required.

     You can test your configuration immediately by adding an email
     address to the `On Save, Send Test Email Message to' box.

     For more information about `Outgoing Email Settings' see, *Note
     mem-outgoing-email-settings::.

   *  `SNMP Traps'

     The `SNMP Traps' section of the `Global Preferences ' page allows
     you to enable Simple Network Management Protocol so that your
     Network Management System (NMS) can handle events created by the
     MySQL Enterprise Monitor. Configure this section to route alerts
     and notifications to standard SNMP-enabled nodes on your network.

     In the `target' text box enter the IP address or the host name of
     your NMS listener. The port number defaults to the well-known SNMP
     port, `162'.  If you are not using this port, enter the port that
     your Network Management System is listening on.

     Enter the appropriate community string in the `Community String'
     text box. The default value for this string is `public'.

     To ensure that the target you have specified is valid, check the
     `On Save, Send Test Trap' check box. The remaining check boxes
     help you to configure how your NMS responds to MySQL Enterprise
     Monitor. Check the `Up/Down Application' check box to configure
     NMS for starting up or shutting down the MySQL Enterprise Monitor.
     For configuration of advisor events choose a level of severity and
     check the `Advisor event with the severity of CRITICAL' check box.
     Finally, choose the `Application Error' check box to configure NMS
     to support application error traps.  Be sure to save your settings
     before exiting.

     If you wish to enable SNMP traps globally, check the `Enable SNMP
     Notifications' checkbox. To enable SNMP traps only for specific
     rules run against specific servers or server groups leave this
     checkbox unchecked -- enabling specific SNMP traps is done as
     rules are scheduled.  For instructions on doing this see *Note
     mem-scheduling-rules::.

     The Management Information Base (MIB) file associated with SNMP
     trapping is called `MONITOR.MIB'. For the location this file see
     The Management Information Base (MIB) File
     (http://dev.mysql.com/doc/mysql-monitor/2.0/en/mem-mib-file-location.html).

   * `Server Locale'

     The `Server Locale' setting determines the language of
     notification for the following items:

        * Email notifications

        * SNMP traps

        * The naming conventions for shared resources such as a
          replication group name prefix

     The initial value in this drop down list box is the locale for the
     OS on which the Dashboard is running.

   *  `Data Purge Behavior'

     The `Data Purge Behavior' section of the `Global Preferences' page
     lets you remove old log files and also old data from the
     repository. The default purge interval is `never'. If you wish to
     purge data, change this setting by choosing from the drop-down
     list. Choosing `52 weeks', for example, will remove all data that
     is older than a year.

     *Warning*:

     Purging data will permanently remove information from the
     repository. Since events are derived from data contained in the
     repository, they will be purged along with the data.

     Ensure that there is adequate disk space for the repository.  If
     you are monitoring numerous servers and running many rules the
     size of the repository can increase rapidly.  Choose purge
     behavior accordingly.

     The default value for purging, `never', is the safest option.
     However, please choose a purge setting that makes sense for your
     environment.

     *Note*:

     The purge process is started approximately once every minute. If
     you change the purge duration from a larger timespan to a smaller
     one, the data may start to be purged immediately.

     You can configure the data purge behavior for a number of
     different systems individually:

        * *Remove Historial Data Collection Older Than* configures the
          duration that the main data about your servers is retained.
          This includes all data collections, including CPU, memory and
          connections and activity statistics.

        * *Remove Service Manager Logs Older Than* configures the
          duration that the main MySQL Enterprise Service Manager logs
          are retained.

        * *Remove Query Analyzer Data Older Than* configures the
          duration tha the query analyzer statistics and information
          about individual queries is retained.

     *Note*:

     Purging can be carried out manually by enabling the
     `innodb_file_per_table' for the repository database and then using
     an `OPTIMIZE TABLE' operation to reclaim space from deleted rows
     in the table.

   * `Remote Server Inventory Schedule'

     MySQL Enterprise Monitor keeps track of all the databases and
     tables in a server, as well as the amount of RAM, disk space, and
     other items. A re-inventory updates this information in case you've
     added or dropped databases and tables. Depending upon the
     configuration of your system, this operation can tax resources. If
     you are monitoring many remote servers this is an operation you
     may want to perform in off-peak hours only.

   * `MySQL Enterprise Credentials'

     You can specify the credentials for logging into the MySQL
     Enterprise Website. These should match the user name and password
     that you have registered with MySQL for your enterprise
     subscription.

     *Note*:

     Only administrators can change the `MySQL Enterprise Credentials'
     section or enter a product key; for other users, this section does
     not show up in the interface.  For more information about
     different users and their rights see *Note mem-managing-users::.
     Specifying incorrect credentials results in the error message,
     `Your credentials do not appear to be valid.'

   * `MySQL Enterprise Product Key'

     You may update your `MySQL Enterprise Product Key'. If you do not
     have access to the Internet from the Dashboard, this provides an
     alternate way to update or activate the MySQL Enterprise Monitor.

     To enter your product key first download it from the MySQL
     Enterprise website. Copy the key to a location accessible from the
     Dashboard. Use the `Browse' button to locate the key and then
     press the `save' button.

     If you wish to switch from using your MySQL Enterprise credentials
     to using a product key to update MySQL Enterprise Monitor, you
     must first clear your credentials. Do this by removing the email
     address from the `MySQL Enterprise Credentials' section and then
     clicking the `save' button. You may then enter and save your MySQL
     Enterprise product key.

     *Note*:

     Only administrators can change the `MySQL Enterprise Credentials'
     section or enter a product key; for other users, this section does
     not show up in the interface.  For more information about
     different users and their rights see *Note mem-managing-users::.
     Specifying incorrect credentials results in the error message,
     `Your credentials do not appear to be valid.'


File: manual.info,  Node: mem-user-preferences,  Next: mem-managing-servers,  Prev: mem-global-settings,  Up: mem-dashboard-settings

15.6.2 User Preferences
-----------------------

On this page users can change their passwords, user names, and locale
information.

FIGURE GOES HERE: MySQL Enterprise Dashboard: User Preferences

Change your password by entering a new value into the `Password' text
box. To change your user name enter a new value into the `Username'
text box.  Click the `save user properties' button to commit this
change.

You may also adjust your time zone and locale information from this
page. The settings on this page apply only to the user who is currently
logged in.

The MySQL Enterprise Service Manager determines the default value for
the locale by looking at your browser settings. Changing this value,
determines the language setting for any future logins to the Dashboard,
overriding your browser settings.

*Note*:

Be sure to set the correct time zone so that alerts are time stamped
correctly.

This setting applies only to the specific user.


File: manual.info,  Node: mem-managing-servers,  Next: mem-managing-users,  Prev: mem-user-preferences,  Up: mem-dashboard-settings

15.6.3 Manage Servers
---------------------

* Menu:

* mem-server-rename::            Renaming a Server
* mem-server-grouping::          Grouping Servers
* mem-deleting-mysql-server::    Removing a Server From the Dashboard

To help with server management, the Service Manager supports the
logical grouping of MySQL servers. This allows you to group servers in
any fashion you choose. For example, you can manage servers according
to purpose. You can group servers by whether the servers handle
Internet or intranet data, by whether they power finance or HR
applications, or, if you prefer, you may organize them by physical
location rather than by functionality.

FIGURE GOES HERE: MySQL Enterprise Dashboard: Manage Servers

For a server to appear in the Dashboard there must be an agent
monitoring it. If you wish to add a server to the Dashboard follow the
procedure for installing an agent found at *Note mem-install-agent::.
Instructions for adding a remote server are found at *Note
mem-install-agent-remote::.

The `Manage Servers' panel also allows you control the Query Analyzer
and Data Migration. For more information, see *Note
mem-query-analysis-settings:: and *Note mem-deployment-migration-2-0::.

*Note*:

The `All Servers' group is built in and every monitored server is a
member of this group.


File: manual.info,  Node: mem-server-rename,  Next: mem-server-grouping,  Prev: mem-managing-servers,  Up: mem-managing-servers

15.6.3.1 Renaming a Server
..........................

You can rename an existing server without losing the current historical
data or configuration information. Renaming the server also allows you
to modify the name of the server to be more descriptive according to
the server's role within your organization. For example, you may want
to rename a server from the default host name to include the department
and application for the MySQL server.

To rename a server, click the `rename' link next to the server. You
will be prompted with information about the server, including the host
name and registered IP addresses for the agent. Fill in the alternative
name that you want to be displayed in the text box at the bottom of the
window.

FIGURE GOES HERE: MySQL Enterprise Dashboard: Server Renaming


File: manual.info,  Node: mem-server-grouping,  Next: mem-deleting-mysql-server,  Prev: mem-server-rename,  Up: mem-managing-servers

15.6.3.2 Grouping Servers
.........................

All monitored servers are automatically included in the top level
server grouping, `All Servers'. Other server groupings are replication
groups or user-defined groups.

You can create a user-defined group by clicking on the `Manage Servers'
link. Add a group name and then click the `create group' button. The
new group will be displayed immediately.

Replication groups are automatically discovered by MySQL Enterprise
Monitor and in this respect differ from user-defined groups. For more
information about replication groups see *Note mem-replication::.
However, like user-defined groups you can edit the name of a
replication group and add other servers to it.

To add to a group, select the `add to group' link. Choose the server or
servers you wish to add and then complete the operation by choosing the
`add to group' button. You can add a server to a group even if the
agent is down.

To remove a server from a group expand the server group tree and click
the `remove from group' link. To delete a server altogether see *Note
mem-deleting-mysql-server::.

*Note*:

Slaves removed from a replication group will be rediscovered and
re-added to that group.

There are three ways to modify an existing group; by renaming it,
adding to it, or removing it. Select the `rename' link to change the
name of a group and `add to group' to add additional servers.  Deleting
a group simply requires clicking the `remove all from group' link. This
removes the server group but has no effect on individual servers.


File: manual.info,  Node: mem-deleting-mysql-server,  Prev: mem-server-grouping,  Up: mem-managing-servers

15.6.3.3 Removing a Server From the Dashboard
.............................................

If you no longer wish to monitor a MySQL server you can remove it from
the Dashboard. There is no provision for deleting an active server from
the Dashboard--to remove a server you must make it inactive by stopping
the agent.

For instructions on stopping an agent see:

   * Windows - *Note mem-starting-agent-windows::

   * Unix - *Note mem-starting-agent-unix::

   * Mac OS X - *Note mem-starting-agent-osx::

Once the agent is stopped you may delete the monitored server.
Deleting a server simply means that it will no longer show up in the
Dashboard.

Remove a server by choosing the `Settings' tab and then the `Manage
Servers' link. Find the server you wish to remove and delete it by
clicking the `delete' link. Deleting a server from the `All Servers'
group or from any other group will remove it from the Dashboard
entirely.

*Note*:

A `delete' link will not appear beside an active server. You must stop
the agent before this link will appear.

You may remove a server from any group at any time. Removing the last
server from a group also removes that group.


File: manual.info,  Node: mem-managing-users,  Next: mem-notification-groups,  Prev: mem-managing-servers,  Up: mem-dashboard-settings

15.6.4 Managing Users
---------------------

The `Manage Servers' panel allows to create, delete and manage
individual users that have access to MySQL Enterprise Service Manager

FIGURE GOES HERE: MySQL Enterprise Dashboard: Manage Users

To log in to the Dashboard a user account is required. There are three
types of users with varying privileges; Administrators, Database
Administrators, and Agents. The `Administrator' can create additional
users and differs from a `DBA' in this respect. For this reason the
`Manage Users' does not display if a DBA user logs in. Additionally,
only administrators can change the MySQL Enterprise Credentials section
or enter a product key on the `Global Settings' page. These sections do
not appear when DBA users log in. For more information on this subject
see *Note mem-global-settings::. The `Agent' account simply allows the
MySQL Enterprise Monitor Agent to communicate with the Dashboard. There
is no need for more than one agent account but defining an account for
each server that is monitored can be an advantage since this minimizes
exposure should any one agent be compromised. You cannot log in to the
Dashboard using the agent's credentials.

When the Dashboard is first launched there are two default users,
`Administrator' and `Agent', both created during installation. Their
default user names are respectively, `admin' and `agent'. The
Administrator defined during installation as having the root role is
unique; this user cannot be deleted.

If you are logged in as an `Administrator', you can add a new user by
choosing the `Manage Users' link from the `Settings' page. To create a
user click the `create user' button, select a role for the user, and
enter a user name and password.

When a new user first logs in, a dialog box opens requesting time zone
and locale information. This information may be changed later from the
`User Preferences' page. For more information, see *Note
mem-user-preferences::.

If you installed the Advisors through the Dashboard you should have
already configured the settings for the root role user. (See *Note
mem-global-settings:: and following for more information about this
topic.)

*Warning*:

To receive MySQL Enterprise and Advisor updates configure the MySQL
Enterprise settings for at least one user. The MySQL Enterprise
settings were set up on the first login to the Dashboard. For
information on changing these settings see, *Note mem-global-settings::.

To edit an existing user's information, select the `Manage Users' link,
then select the user you wish to edit. Make your desired changes in the
fields provided and then save your changes.

To delete an existing user, merely select the `delete' link.


File: manual.info,  Node: mem-notification-groups,  Next: mem-logs,  Prev: mem-managing-users,  Up: mem-dashboard-settings

15.6.5 Manage Notification Groups
---------------------------------

The `Manage Notification Groups' panels allows you to create and manage
the notification groups used when different notifications and warnings
are distributed.

FIGURE GOES HERE: MySQL Enterprise Dashboard: Manage Notification Groups

Notification groups are collections of users who should be notified
when advisor alerts occur. These users may have login credentials for
the Dashboard but this is not a requirement.

You can create a group by clicking on the `create group' link. Specify
a group name and add recipients.  When adding a user an email address
must be specified. If you are adding multiple users separate them with
commas.

To modify an existing notification group, select the `edit' link next
to the group name. Deleting a group simply requires clicking the
`delete' link.

If a rule triggers an alarm, an email will be sent to the members of
the notification group specified when the rule was scheduled.  For more
information about scheduling rules see *Note mem-scheduling-rules::.

*Note*:

You should ensure that there is a mail server available for sending out
alerts and that there is an account configured for receiving any alerts
that are created.


File: manual.info,  Node: mem-logs,  Next: mem-product-info,  Prev: mem-notification-groups,  Up: mem-dashboard-settings

15.6.6 Logs
-----------

Use the `Logs' link to inspect the various log files associated with
the MySQL Enterprise Service Manager. The following image is an example
of this screen.

FIGURE GOES HERE: MySQL Enterprise Dashboard: Logs

The various categories of logs are shown in alphabetical order.  The
most recent changes to each log are shown in the `Last Modified'
column. The number of entries in any specific log is shown under the
`Entries' column.

To view detailed information click the `Log Name'. This will open a
separate browser window showing the date, time, alert type, and
accompanying message.

On this screen you can filter log information in a couple of ways; by
the message type and by time period .

To filter by message type select from the options in the `level'
drop-down box. These are, in order of decreasing severity:

   * All

   * Error

   * Warning

   * Information

   * Trace

   * Debug

You can also adjust the number of items that appear on each page.

Press the `clear all logs' link to remove all log entries. To remove
entries of a specific kind click the `clear logs' link associated with
the specific log you would like to remove. A confirmation dialog box
allows you to back out of this operation and avoid accidentally
removing log information.

To clear log files of a specific age see the `Data Purge Behavior'
section of the `Global Preferences' page. For more information on this
topic see *Note mem-data-purge::.

Use the `edit log level' link to change the type of error logged. The
value selected from the `Edit Log Level' dialog box determines what
appears under the `Threshold' column (second from the left in *Note
mem-data-purge::).

Selecting `Error' from the list box will create the least number of log
entries and `Debug' the most. Choosing `None' turns off logging
altogether.

It is also possible to download a compressed version of all the log
files. For more information, see *Note mem-product-info::.


File: manual.info,  Node: mem-product-info,  Prev: mem-logs,  Up: mem-dashboard-settings

15.6.7 The Product Information Screen
-------------------------------------

* Menu:

* mem-subscriptions-warning::    Subscription Warning

Use the `Product Information' link to view detailed information about
your subscription level and contract status.

The `Contract Status' section displays the subscription level,
expiration date, contract number, the number of servers supported, and
your MySQL Enterprise user name. The `Subscription Level' section gives
more detailed information, including features and any restrictions that
may apply. You may update your subscription at any time by clicking the
`update' button.

*Note*:

The `update' button was added in version 1.3 of the MySQL Enterprise
Monitor. If your version of MySQL Enterprise Monitor does not have an
`update' button, saving your credentials again will download a new key.
See *Note mem-global-settings:: for instructions on doing this. If you
do not have Internet access from the Dashboard, you can install a new
key manually. This process is described in *Note mem-global-settings::.

This page also contains Enterprise Dashboard Server information; the
version number, uptime, and other information related to the memory
used by the Java Virtual Machine.

The `Enterprise Dashboard Server information' section also contains the
hyperlink, `Download diagnostic report'. Click this link to download a
compressed version of the MySQL Enterprise Service Manager log files.
All the log files found on the `Logs' page (for more information about
logs see *Note mem-logs::) are contained in this file. It also contains
the Java properties file, the monitored MySQL servers property file,
information about the status of the JDBC connection and Java threads,
and the `subscription.xml' file. This report is especially useful for
debugging the MySQL Enterprise Service Manager and the MySQL Enterprise
Monitor Agent.


File: manual.info,  Node: mem-subscriptions-warning,  Prev: mem-product-info,  Up: mem-product-info

15.6.7.1 Subscription Warning
.............................

The `Subscriptions Warning' section on the product information page
displays any warnings relative to your subscription. For example, if
your subscription has expired you may receive a message such as the
following:

     Your Subscription Needs to be Updated
     * Your Platinum subscription expired 3 days ago on Feb 14, 2008 11:59:59 PM.
     If the subscription information on this page is not current, you can
     update it by going to the Enterprise Monitor Global Settings page and
     providing MySQL Enterprise credentials or by importing a new product
     key that you downloaded from http://www.mysql.com/enterprise/download.php.
     To update or renew your subscription, please contact your MySQL
     Account Representative at sales@mysql.com or visit
     http://www.mysql.com/about/contact/renew.html.  After the update or
     renewal is complete you can then follow the above instructions for
     updating your subscription.

Follow these instructions to update your subscription. If you see this
message and your subscription has already been updated, simply click
the `update' button in the `Contract Status' section of this page. This
should update your subscription and remove the warning.

*Note*:

After updating your subscription remember to also update your advisors.
For instructions on doing this see *Note mem-update-advisors::.


File: manual.info,  Node: mem-advisors,  Next: mem-events,  Prev: mem-dashboard-settings,  Up: mem-introduction

15.7 The Advisors Page
======================

* Menu:

* mem-update-advisors::          Installing and Updating Advisors
* mem-scheduling-rules::         Scheduling Rules
* mem-editing-built-in-rules::   Editing Built-in Rules
* mem-creating-advisors-and-rules::  Creating Advisors and Rules
* mem-unscheduling-advisors::    Disabling and Unscheduling Rules
* mem-advisor-blackouts::        Advisor Blackout Periods

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

MySQL Enterprise Advisors are a series of scripts that gather
information from your MySQL servers via the Service Manager and the
Service Agents, analyze that information based on custom rules
developed by MySQL AB, and then offer alerts and advice when necessary.
As new rules are introduced, the MySQL Enterprise Advisors can be
updated through the MySQL Enterprise website.

The MySQL Enterprise Advisors fall into the following categories:

   * Administration

        * Better manage databases

        * Suggest improvements for smoother operation

   * Heat Chart

        * Drive the status indicators in the Heat Chart

        * Identify up/down status and performance issues

   * Performance

        * Identify potential performance bottlenecks

        * Make suggestions for improved database speed

   * Replication

        * Identify replication bottlenecks

        * Improve replication design

   * Schema

        * Identify schema changes

        * Find security loopholes

   * Security

        * Protect MySQL servers

        * Find security loopholes

An advisor category provides a set of rules designed to enforce MySQL
best practices for that specific category. Rules can be targeted to run
at the individual server or group level and, upon rule violation,
provide alerts and expert advice on how to address and correct a
problem before it becomes a costly outage.

Individual rules are defined in the `items-mysql-monitor.xml' file. On
Windows this file is found in the `C:\Program
Files\mySQL\Enterprise\Agent\share\mysql-monitor-agent' directory and
on Unix in the `/opt/mysql/enterprise/agent/share/mysql-monitor-agent'
directory. Find below the rule for discovering a `root' account with no
password.

     <ITEM>
       <NAME>no_root_password</NAME>
       <FIELD>no_password</FIELD>
       <SCOPE>table</SCOPE>
       <CODE>
         <![CDATA[SELECT COUNT(*) AS no_password FROM mysql.user WHERE user='root' AND password='']]>
       </CODE>
       <NAMESPACE>mysql</NAMESPACE>
       <RETURNS>INTEGER</RETURNS>
       <SOURCE>table</SOURCE>
       <INSTANCE>mysql.user</INSTANCE>
     </ITEM>

Your MySQL Enterprise subscription level determines which rules are
available to you. Subscription levels are cumulative, meaning that
higher MySQL Enterprise levels have access to all the rules of the
lower levels.

When the Dashboard is first installed, the only rules that are
scheduled are those that belong to the `Heat Chart' group.

Go to the Advisors screen by logging in to the Dashboard and choosing
the `Advisors' tab.


File: manual.info,  Node: mem-update-advisors,  Next: mem-scheduling-rules,  Prev: mem-advisors,  Up: mem-advisors

15.7.1 Installing and Updating Advisors
---------------------------------------

Instructions for installing Advisors are given in *Note
mem-advisor-installation-after-login::, and following. Principally, you
need to configure your MySQL Enterprise login or enter your product key
before you can update your Advisors.

If your MySQL Enterprise login is configured, you can download the
latest Advisors by navigating to the `Advisors' page and finding the
`Check for Updates' link. You can periodically update advisors in this
way.

*Note*:

If you do not have Internet access and cannot use the online update
option you can manually import advisors. This process is described in
*Note mem-advisor-installation-after-login::.


File: manual.info,  Node: mem-scheduling-rules,  Next: mem-editing-built-in-rules,  Prev: mem-update-advisors,  Up: mem-advisors

15.7.2 Scheduling Rules
-----------------------

* Menu:

* mem-heat-chart-notifications::  Heat Chart Notifications

Once the MySQL Enterprise Advisors have been installed, you can
configure which advisors you would like to run on a scheduled basis.

You can schedule rules by individual server or by group. This is done
by first selecting the desired server or server group from the `Server'
tree found on the left side of the screen. Next select the `Advisors'
tab.

Opening the `Advisors' tab takes you to the `Current Schedule' page. If
you have only just installed the MySQL Enterprise Monitor then you will
only see the `Heat Chart' group of advisors. Clicking the `+' button
will show all the rules in the Heat Chart group.

Clicking the `+' button beside any specific rule will show the servers
that this rule is running on, its frequency, and its status. Initially,
all the `Heat Chart' rules are enabled.

For a more complete description of a rule, click the rule's name.  This
opens a dialog box that gives detailed information about the rule.

To view the advisors other than the Heat Chart group, select the `Add
to Schedule' link. This will show all the advisors available for your
subscription level.

Rules are grouped by functionality and displayed in alphabetic order.
To expand a group click the `+' button to the left of the advisor name.

You may activate all the rules in a group by selecting the checkbox
beside the group name. Once selected you may apply rules against a
specific server or a group of servers. A message showing the group of
servers or the specific server you have selected will display
immediately below the `schedule' button. For example, if the `All
Servers' group is selected in the server tree, then the message will
read, `Schedule Advisors Against *All Servers*'.

To select a specific rule, expand the group tree by clicking the `+'
button. Select the checkbox to the left of the rule you wish to
schedule. Click `schedule' to display the following dialog box:

FIGURE GOES HERE: MySQL Enterprise Dashboard: Scheduling Dialog

The Schedule dialog box allows you to configure the following fields:

   * `Frequency' - Dictates how often the rule will run. The default
     value for different rules varies but a rule can be set to run at
     any interval desired.

     *Warning*:

     Setting the frequency of a rule involves tradeoffs. Rule
     evaluation consumes system resources -- CPU, memory, and disk
     space. While the amount consumed is small, if you run all the
     rules against dozens of servers on a very frequent basis, you may
     put a significant load on the Service Manager. So select an
     appropriate frequency. For example, unless you are stopping and
     restarting your servers frequently, rules that check server
     configuration variables probably don't need to run very often.

     Another consideration is that certain status variables increase
     monotonically until a server is restarted. Examples of these are
     `Key_reads', `Qcache_hits', `Questions', `Table_locks_waited', and
     similar variables. The value returned by `SHOW STATUS' for these
     variables is the value since the server was started (or since the
     last `FLUSH STATUS' command), which is not very useful for
     performance tuning, especially if the server has been running for
     an extended period of time. For performance tuning it is much
     better to know the change in state (i.e.  delta) of these values
     over the last 10 minutes, 1 hour, or whatever time frame is
     appropriate for your application. The frequency at which you
     schedule a rule is the time frame used to calculate the delta
     values of these variables, and it is the delta that is used in
     expression evaluation, not the absolute value. Consequently,
     select a frequency that is appropriate for the metrics being used
     in the expression.

   * `Notifications' - A listbox of users and/or notification groups
     who will be emailed when an advisor reaches an alert level. Single
     or multiple selections are allowed. For instructions on setting up
     notification groups see, *Note mem-notification-groups::.

Set the frequency, identify whomever you wish to notify, and click
`schedule' to schedule the advisor. Upon completion, you should see the
message, `Successfully scheduled'.

If you haven't set up global SNMP traps and would like your Network
Management System (NMS) to handle events related to a specific rule
then check the `Use SNMP Traps' checkbox. For more information about
Simple Network Management Protocol (SNMP) see Simple Network Management
Protocol (SNMP) Traps.

Scheduling rules using the checkbox and the `schedule' button is an
effective way to schedule multiple rules. To schedule a single rule you
may also use the `schedule' link.

When scheduling more than one rule, you have the option of selecting a
checkbox to use the default frequency of each rule or you may choose a
frequency that will apply to all selected rules.  When customizing the
frequency, take care that you choose a value that is appropriate to all
the rules selected.

*Note*:

If the agent does not have the `SUPER' privilege and InnoDB-related
rules are scheduled, a warning will appear in the `DataCollection' log.
This also occurs if `mysqld' is started with the `skip-innodb' option.
For more information about agent rights see *Note mem-agent-rights::.


File: manual.info,  Node: mem-heat-chart-notifications,  Prev: mem-scheduling-rules,  Up: mem-scheduling-rules

15.7.2.1 Heat Chart Notifications
.................................

It is particularly important that `Notifications' be set for the `Heat
Chart' group of rules. This is easily done from the `Current Schedule'
page by clicking the `+' button beside a rule and then clicking a
server.

Doing this opens a window with three tabs--`Overview', `Settings', and
`Advanced'.

The `Overview' tab shows which advisor group a rule belongs to, a
description of its purpose, and a link to the history of this alert.

In the `Settings' tab you can adjust the frequency of this rule and
also specify a notification group. To select more than one contiguous
group press the `Shift' key and click the desired groups. (Some web
browsers may require that you drag your selection.)  Non-contiguous
selections are made by holding down the `Control' key and clicking the
desired groups.

If you haven't set up global SNMP traps and would like your Network
Management System (NMS) to handle events related to a specific rule
then check the `Use SNMP Traps' checkbox. For more information about
Simple Network Management Protocol (SNMP) see *Note mem-snmp-traps::.

The `Advanced' tab gives detailed information about how this rule is
implemented.


File: manual.info,  Node: mem-editing-built-in-rules,  Next: mem-creating-advisors-and-rules,  Prev: mem-scheduling-rules,  Up: mem-advisors

15.7.3 Editing Built-in Rules
-----------------------------

The frequency and thresholds defined for a rule are default
recommendations. To edit these properties choose the `Create/Edit Rule'
link.

The following image shows the screen used to edit rules:

FIGURE GOES HERE: MySQL Enterprise Dashboard: Editing Rules

Beside the rule name is the `Advisor' drop-down list box, used for
setting the advisor group. This list box shows existing groupings and
any you may have added. The `Expression' textarea shows the advisor
rule, `Variable Assignment' the data item associated with variable(s)
used in the rule and `Thresholds' determines when to trigger each alert
type.

The three levels of `Thresholds' are `Info Alert', `Warning Alert', and
`Critical Alert' indicating increasing levels of severity. Levels can
be triggered by the expression result being equal to a certain value,
greater than a certain value, or less than a certain value.

The data items that variables are associated with are operating system
(OS) properties such as available RAM or MySQL characteristics such as
the InnoDB buffer pool. To see all available data items drop down the
`Data Item' list box. For a listing of these data items see The Data
Collection Items Used to Create Rules
(http://dev.mysql.com/doc/monitor/2.0/en/mem-data-items.html).

In *Note fig-mem-edit-advisor:: the drop-down `Data Item' list box
within the `Variable Assignment' frame shows the various MySQL server
status or operating system specific variables that may be used in
expressions. The text boxes below `Thresholds' define the levels at
which informational, warning, or critical alerts are issued.

To lower the threshold for an informational alert, simply increase the
number given in the `Info Alert' text box.

When a data item can apply to multiple objects, you need to specify
which instance to use for that item, hence the `Instance' text box. In
almost all cases this should be set to `local'. The exceptions are as
follows:

   * For CPU-related items set `Instance' to `cpu0'. Additional CPUs on
     a system are referred to as `cpu1, cpu2' and so on.

   * There can be multiple disks mounted on a system. To refer to a
     specific drive set `Instance' to the name of of the mounted drive.
     On Windows this would be `C:, D:', and so on. On Unix systems, use
     whatever is valid for the `df' command.

   * For RAM-related items set `Instance' to `mem'.

   * Where there are table-specific variables, the database name and
     table name must be specified in the `Instance' text box. This
     topic is discussed in detail in what follows.

*Note*:

It is not possible to have a data item that is unrelated to an
instance. This raises the error, `You must map "<variable>" to an
instance', and you will be unable to save the rule.

An agent can only collect data from one MySQL server, so the `instance'
entry for a variable in a rule does not need to specify which MySQL
server to use; no matter how many servers are being monitored there is
always a one-to-one relationship between an agent and its monitored
server.

However, on one server there may be multiple occurrences of a variable.
For example, there are multiple possible occurrences of table-specific
variables such as `Avg_row_length' because there can be multiple
databases and tables defined in a MySQL server. In this case, the
`instance' refers to the database and table that a data item should be
associated with, specified in the form DATABASENAME.TABLENAME.  So, for
example, if you want to reference the `Avg_row_length' of the `mysql'
database `user' table in an expression, select the
`mysql:tablestatus:Avg_row_length' from the `Data Item' list box and
specify `mysql.user' in the `Instance' text box.

On the other hand, in the case of a global server variable, there is
only one possible target. For example, there can only be one instance
of `delay_key_write' because this variable is global and applies to the
server as a whole. In this case specify `local' in the `Instance' text
box.

To save your changes click the `save' button at the bottom of the page.

*Note*:

You can change only the thresholds and the frequency of built-in rules.
So that rules function properly when updated, other changes are
prohibited.

Should you wish to make other changes to a built-in rule, copy it and
modify it as desired.

You can edit a rule even if it is currently scheduled. Your changes
will not be overwritten when new rules are imported using the `Check
for Updates' link.


File: manual.info,  Node: mem-creating-advisors-and-rules,  Next: mem-unscheduling-advisors,  Prev: mem-editing-built-in-rules,  Up: mem-advisors

15.7.4 Creating Advisors and Rules
----------------------------------

* Menu:

* mem-creating-advisors::        Creating Advisors
* mem-creating-rules-overview::  Overview of Rule Creation
* mem-advisors-variables::       Variables
* mem-advisors-thresholds::      Thresholds
* mem-advisors-using-strings::   Using Strings
* mem-advisors-wiki-format::     Wiki Format
* mem-example-creating-rule::    Creating a New Rule: An Example
* mem-custom-data-collection-item::  Creating a Custom Data Collection Item

In addition to using and editing the advisors and rules provided by
MySQL Enterprise, users can create their own advisors and rules to meet
their own unique needs. To do this go to the `Advisors' page and choose
the `Create/Edit Rule' link.


File: manual.info,  Node: mem-creating-advisors,  Next: mem-creating-rules-overview,  Prev: mem-creating-advisors-and-rules,  Up: mem-creating-advisors-and-rules

15.7.4.1 Creating Advisors
..........................

Similar existing rules are grouped together in advisor groups.

The built-in advisors are:

   * Administration

   * Heat Chart

   * Performance

   * Replication

   * Schema

   * Security

The ability to create your own advisor group allows you to create
groupings suitable to your circumstances.

You can create your own grouping by simply clicking the `create
advisor' button. Enter an appropriate name and click the `add' button.
The newly created group will appear in the `Advisor' column.

The newly created advisor is added to the list box of advisors shown in
*Note fig-mem-edit-advisor::. You can now use this category of advisors
when you create a new rule.


File: manual.info,  Node: mem-creating-rules-overview,  Next: mem-advisors-variables,  Prev: mem-creating-advisors,  Up: mem-creating-advisors-and-rules

15.7.4.2 Overview of Rule Creation
..................................

Rules are created using the same screen seen in *Note
fig-mem-edit-advisor::. To begin creating a rule from scratch, click
the `create rule' button. However, the simplest way to create a new
rule is to copy an existing one. Unlike editing an existing rule, when
you copy a rule, every element of that rule is editable.

You can change the rule name, the advisor group that a rule belongs to
and you can set your own version number. In *Note
fig-mem-edit-advisor::, you have already seen how the threshold and
frequency of a rule may be altered.

Most importantly you can alter a rule's expression. Expressions are the
core of a MySQL Enterprise Advisor and are used to define the scenario
being monitored. An expression can be as simple as a single server
parameter or can be quite complex, combining multiple parameters with
various mathematical operations.

An expression has two main characteristics:

   * An expression defines a situation where a best practice is not
     being followed

   * The result of an expression must always be 1 or 0 (that is, true
     or false)

If an expression evaluates to true for a specific server, an alarm is
raised, indicating that a best practice is not being followed. If an
expression evaluates to false no alarm is raised because the best
practice is indeed being followed.

For example, if having binary logging enabled is considered a best
practice for a production server (which we believe it is), then this
best practice is being violated if `log_bin' is `OFF'.  Consequently,
the expression for the `Binary Logging Not Enabled' rule is `%log_bin%
== OFF'. If this evaluates to 1, an alarm is raised because the best
practice is not being followed.

An expression is made up of one or more variables and zero or more
mathematical operators. The MySQL Enterprise Monitor uses the MySQL
database server's expression parser and evaluator For a complete list
of operators and functions see
`http://dev.mysql.com/doc/refman/5.0/en/functions.html'. For a complete
list of the built-in variables used when creating rules see
`http://dev.mysql.com/doc/refman/5.0/en/mysqld-option-tables.html'.

Creating an expression is dependent on variables defined in the
`Variable Assignment' frame. This frame links variables used in the
expression field with data gathered from the target MySQL server
instance--server status variables, operating system status information,
and table information.  Variable names are associated with elements in
the `Data Item' drop-down list. If you need to define more than one
variable simply click the `add row' button. For a complete listing of
the data collection items used in creating rules see The Data
Collection Items Used to Create Rules
(http://dev.mysql.com/doc/monitor/2.0/en/mem-data-items.html).

The remaining fields determine the information that displays in a
notification email or the informational pop-up window associated with
each advisor.

*Note*:

When saving a new rule ensure that you do not duplicate the name of an
existing rule.


File: manual.info,  Node: mem-advisors-variables,  Next: mem-advisors-thresholds,  Prev: mem-creating-rules-overview,  Up: mem-creating-advisors-and-rules

15.7.4.3 Variables
..................

When an expression is evaluated variables get replaced by values. For
example, part of the expression for the `MyISAM Key Cache Has
Sub-Optimal Hit Rate' rule calculates the hit rate as follows:

     100-((%Key_reads% / %Key_read_requests%)*100)

If the current value of `%Key_reads%' is 4522 and the current value of
`%Key_read_requests%' is 125989, the hit ratio assesses to 96.4%:

     100 -((4522 / 125989) * 100)

By convention, the Advisors supplied by MySQL use ``%'' as the
delimiter, for example, `%Key_reads%'. This makes variables more
readily identifiable.

In addition to being used in an expression, variables may also be used
in the `Description', `Advice', `Action', and `Links' attributes of a
rule. This allows you to report the current value of an expression.

For instance, you can add the message, `The current value of Key_reads
is %Key_reads%.' to the `Advice' text box. When this is displayed on
the screen, the value of `%Key_reads%' is substituted into the text.
Supposing `%Key_reads%' has a value of `4522', the message becomes `The
current value of Key_reads is 4522.'


File: manual.info,  Node: mem-advisors-thresholds,  Next: mem-advisors-using-strings,  Prev: mem-advisors-variables,  Up: mem-creating-advisors-and-rules

15.7.4.4 Thresholds
...................

Each expression has a threshold value that triggers an alert.  The
`THRESHOLD' keyword is used to associate that value with an alert
level--either an `Info', `Warning', or `Critical' alert.

For example, the expression for the performance advisor, `Thread Cache
Size May Not Be Optimal', is:

     100-((%Threads_created% / %Connections%) * 100) < THRESHOLD

The `THRESHOLD' is set at 95% for an Info level alert, 85% for a
Warning alert, and 75% for a Critical alert; producing alerts of three
different levels.

Expressions can be quite simple. The expression for `Binary Logging Not
Enabled' (one of the Administration alerts) is:

     %log_bin% == THRESHOLD

When the result is `OFF', only one alert is triggered--a Warning level
alert. In this situation you might think we could just use the
expression `%log_bin% == "OFF"'. However, doing this would not test
binary logging against a threshold so would not result in an alert.

When you create an expression, think carefully about the conditions
under which it should be evaluated and the conditions under which it
should not. For example, the expression for the `MyISAM Key Cache Has
Sub-Optimal Hit Rate' rule is:

     (%Uptime% > 10800) && (%Key_read_requests% > 10000) »
      && (100-((%Key_reads% / %Key_read_requests%) * 100) < THRESHOLD)

The essence of the rule is really: `(100-((%Key_reads% /
%Key_read_requests% ) * 100) < THRESHOLD)'. However, when a server is
first starting up, it may take a while to reach a state that is
representative of normal operations. For example, the key cache and the
query cache may need some period of time before they have cached
typical application data as opposed to start-up and initialization
data. In this case, the first part of the expression, `(%Uptime% >
10800)', holds off evaluating this expression until the system has been
running for 10800 seconds (3 hours).

In addition, if some part of the system is not heavily used an alert
may be triggered based on limited data. For example, if your
application does not use the MyISAM storage engine, the `MyISAM Key
Cache Has Sub-Optimal Hit Rate' rule may be triggered based on very
limited use of other MyISAM tables such as the `mysql.user' table. For
this reason, this advisor has a second part-- `(%Key_read_requests% >
10000)'-meaning the rule won't be evaluated unless there is plenty of
activity associated with the key cache.

In other circumstances, there may be periods of time during which you
don't want a rule to be evaluated--a blackout period. For example, the
expression for the `Slave Too Far Behind Master' rule is:
`%Seconds_Behind_Master% > THRESHOLD'. However, suppose you run a backup
process between 6 and 7 pm on a replication slave, and it's normal for
that slave to get behind the master by an amount more than the
THRESHOLD during that time. In that case you don't want to receive an
alert because the rule violation is expected. You can achieve this by
adding the following to the expression: && CURTIME() NOT BETWEEN
'18:00:00' AND '19:00:00' In essence, this means `don't trigger an
alert between 18:00:00 and 19:00:00 (6 pm and 7 pm)'.


File: manual.info,  Node: mem-advisors-using-strings,  Next: mem-advisors-wiki-format,  Prev: mem-advisors-thresholds,  Up: mem-creating-advisors-and-rules

15.7.4.5 Using Strings
......................

String values may appear in the `Expression' or the `Thresholds' text
boxes. In both cases, they must be enclosed within quotation marks. For
example, the expression for the `Slave I/O Thread Not Running' rule is:

     (%Slave_running% == "ON") && (%Slave_IO_Running% != THRESHOLD)

In similar fashion the `Critical Alerts' threshold text box is set to a
value of `"Yes"'.

When the expression is evaluated, either `"OFF"' or `"ON"' will be
substituted for `%Slave_running%', and `"Yes"' or `"No"' for
`%Slave_IO_Running%', depending on the state of your system. If the
slave is running but the I/O thread is not, the expression then becomes:

     ("ON" == "ON") && ("No" != "Yes")

Without quotation marks this expression would not evaluate to `TRUE' as
it should.

*Note*:

So that it is interpreted properly, the `==' operator is converted to
`=' before being passed to the MySQL expression parser.


File: manual.info,  Node: mem-advisors-wiki-format,  Next: mem-example-creating-rule,  Prev: mem-advisors-using-strings,  Up: mem-creating-advisors-and-rules

15.7.4.6 Wiki Format
....................

When editing or defining a rule, the text entered in the `Problem
Description', `Advice', `Recommended Action', and `Links and Further
Reading' text boxes may be formatted in Wiki format.  This allows you
to format text and add hyperlinks when creating or editing your own
rules.

Find a brief introduction to using Wiki formatting in the following
table.

*MySQL Enterprise Monitor: Wiki formatting*

*Example*      *Description*
__BOLD__       boldface text
~~ITALIC~~     italicize text
\\             create a line break
\\ \\          create a double line
               break
\\\\G          create a backslash
*ITEM 1        create a bulleted
               list item
#ITEM 1        create a numbered
               list item
\_             use the ``\'' to
               escape special
               characters
{moreInfo:name|url}create a hyperlink

So the following Wiki text:

     Replication is a __very nice feature__ of MySQL.  Replication can be very
     useful for solving problems in the following areas:
     * Data Distribution
     * Load Balancing
     * Backup and Recovery
     You can check replication status and start a slave using the following
     commands: SHOW SLAVE STATUS \\\\G\\START SLAVE;
     {moreInfo:MySQL Manual: Replication
           FAQ|http://dev.mysql.com/doc/refman/5.0/en/replication-faq.html}

Would be translated into the following HTML markup:

     Replication is a <b>very nice feature</b> of MySQL.  Replication can be very
     useful for solving problems in the following areas:
     <ul>
       <li>Data distribution</li>
       <li>Load Balancing</li>
       <li>Backup and recovery</li>
     </ul>You can check replication status and start a slave with the following
     commands: SHOW SLAVE STATUS \G;<br/>START SLAVE;
     <a href="../mysql-monitor-2.0/http://dev.mysql.com/doc/refman/5.0/en/replication-faq.html"
       target="_blank" >MySQL Manual: Replication FAQ</a>

To find out more about this format go to the wikipedia.org
(http://wikipedia.org) web site.


File: manual.info,  Node: mem-example-creating-rule,  Next: mem-custom-data-collection-item,  Prev: mem-advisors-wiki-format,  Up: mem-creating-advisors-and-rules

15.7.4.7 Creating a New Rule: An Example
........................................

This section documents the steps required to create a rule.  Before
attempting to create a rule, please review the preceding sections of
this chapter.

This example creates a rule that checks the number of rows in a table.
Having 50,000 rows in this table is deemed to warrant a critical alert.
Lesser numbers are assigned to informational and warning level alerts.

Begin by navigating to the `Advisors' tab and clicking the `manage
rules' link. Then choose the `create rule' button.

Create your custom rule by following these steps:

  1. Using the `Rule Name ' text box, give the rule an appropriate
     name. Something such as "Excessive number of records in TABLE_NAME
     table", may be appropriate.

  2. From the `Advisor' drop down list box choose an advisor group for
     your rule. The `Administration' group of rules might be suitable
     but if you wish, create your own group of advisors. For
     instructions on doing this see *Note mem-creating-advisors::.

  3. Enter the following expression in the `Expression' text area:
     '%TABLE_NAME_num_rows% > THRESHOLD'. Replace TABLE_NAME with the
     name of the table you wish to monitor. Note that the variable
     `%TABLE_NAME_num_rows% ' has not yet been defined.

  4. Set the Thresholds.

       1. Set the `Critical Alert' level to `50000'.

       2. Set the `Warning Alert' level to `10000'.

       3. Set the `Info Alert' level to `5000'.

  5. Define your variable in the `Variable Assignment' frame.

       1. In the `Variable' text box enter `'%TABLE_NAME_num_rows%',
          the variable used in the `Expression' text box

       2. In the `Data Item' drop down list box find and select the
          `mysql:table:numrows' entry. (For a description of all the
          data items available see The Data Collection Items Used to
          Create Rules
          (http://dev.mysql.com/doc/monitor/2.0/en/mem-data-items.html).)

       3. In the `Instance' text box enter DATABASE_NAME.TABLE_NAME.

  6. Add appropriate entries for the `Problem Description', the
     `Advice', and the `Links' text areas. If you wish, use Wiki markup
     for these text areas. See *Note mem-advisors-wiki-format:: for more
     information. Note that you can also reference the
     `'%TABLE_NAME_num_rows%' variable in these text areas. For
     example, you can display the current number of rows with a message
     such as 'TABLE_NAME currently has %TABLE_NAME_num_rows% rows.'

  7. Save the rule.

Once the rule is created it needs to be scheduled against the server
that contains the database table you wish to monitor. For instructions
on scheduling rules see *Note mem-scheduling-rules::.


File: manual.info,  Node: mem-custom-data-collection-item,  Prev: mem-example-creating-rule,  Up: mem-creating-advisors-and-rules

15.7.4.8 Creating a Custom Data Collection Item
...............................................

* Menu:

* mem-custom-data-item-xml-file::  Creating and Using a Custom Data Item XML File

*Note mem-example-creating-rule:: shows how to create a custom rule and
The Data Collection Items Used to Create Rules
(http://dev.mysql.com/doc/monitor/2.0/en/mem-data-items.html) shows the
data items that can be used in rule creation. However, in some
circumstances you may want to create a rule that uses a custom data
collection item.

This section describes how to create a custom data collection item. The
steps are as follows:

  1. Create an XML file to define how the data is collected.

  2. Point the agent configuration file to this XML file.

  3. Restart the agent.


File: manual.info,  Node: mem-custom-data-item-xml-file,  Prev: mem-custom-data-collection-item,  Up: mem-custom-data-collection-item

15.7.4.9 Creating and Using a Custom Data Item XML File
.......................................................

As an example, this section shows how to create a data item for
monitoring the amount of free InnoDB tablespace. The format and content
of the XML file that defines the data to be collected is as follows:

     <?xml version="1.0" encoding="utf-8"?>
     <classes>
       <class>
         <classname>innodb_min_free</classname>
         <namespace>mysql</namespace>
         <query><![CDATA[SELECT MIN(substring_index(substring_index(table_comment," ",3)," ",-1)/1024/1024)
           as Free FROM INFORMATION_SCHEMA.TABLES WHERE engine = 'InnoDB']]></query>
       </class>
     </classes>

Save this file as:

   * Windows - `C:\Program
     Files\MySQL\Enterprise\Agent\share\mysql-proxy\items\innodb_min_free.xml'

   * Unix -
     `/opt/mysql/enterprise/agent/share/mysql-proxy/items/innodb_min_free.xml'

   * Mac OS X -
     `/Applications/mysql/enterprise/agent/share/mysql-proxy/items/innodb_min_free.xml'

After saving this file, you must point your `mysql-monitor-agent.ini'
file to it. ( For the location of this file on your operating system see
*Note mem-cfg-mysql-monitor-agent-ini::.) Find the `[mysql-proxy]'
section and add the file name `innodb_min_free.xml' to the `item-files'
parameter using a semi-colon as a separator. For example:

     [mysql-proxy]
      ...
     item-files = items-mysql-monitor.xml,innodb_min_free.xml
      ...

For this change to take effect you must restart the agent. To do this
see:

   * Windows - *Note mem-starting-agent-windows::

   * Unix - *Note mem-starting-agent-unix::

   * Mac OS X - *Note mem-starting-agent-osx::

Once the agent has restarted, you will find the new data item in the
`Data Item' drop down list box on the `Rule Definition' page. Its fully
qualified name is `mysql:table:innodb_min_free'.


File: manual.info,  Node: mem-unscheduling-advisors,  Next: mem-advisor-blackouts,  Prev: mem-creating-advisors-and-rules,  Up: mem-advisors

15.7.5 Disabling and Unscheduling Rules
---------------------------------------

In some circumstances you may no longer wish to apply a rule against a
specific server or group of servers and in other circumstances you may
want to suspend a rule for a short length of time. With this in mind,
it is possible to disable or unschedule a rule.

To disable or unschedule an advisor choose the `Current Schedule '
screen of the `Advisors' tab.

Rules may be disabled or unscheduled using the buttons on the upper or
lower left of the screen. You may also change a rule by clicking the
`enabled' or `unschedule' hyperlink to the right of a rule.  The
buttons are particularly useful when you are altering more than one
rule.

To no longer run a rule against a specific server, expand the advisor
group and the specific rule by clicking the `+' button. You may then
click the `unschedule' button. When the dialog window opens, choose the
`unschedule' button and that rule will no longer be applied. If you
wish to back out of the operation choose `cancel'. If, at a later date,
you wish to institute this rule again, you may do so from the `Add to
Schedule' page.

If you want to suspend a rule temporarily, use the `disable' button and
follow the same process you would for unscheduling. Once a rule is
disabled the link under the status column changes to red and reads
`disabled'. When a rule is disabled, data is no longer collected for
that rule. A disabled rule is easily re-enabled by clicking the
`disabled' link or by using the `enable' button.

Multiple rules may be altered for one or more servers by selecting the
appropriate checkbox and then clicking the `unschedule', `enable', or
`disable' button.

*Note*:

Rules associated with the heat chart cannot be disabled or unscheduled
as they are required by MySQL Enterprise Monitor.


File: manual.info,  Node: mem-advisor-blackouts,  Prev: mem-unscheduling-advisors,  Up: mem-advisors

15.7.6 Advisor Blackout Periods
-------------------------------

* Menu:

* mem-advisor-scripting-blackouts::  Scripting Blackouts

Database servers require regular maintenance and during these periods
you may wish to stop Monitor Agents from reporting their findings.
During a blackout period rules are not evaluated and notifications are
put on hold but Monitor Agents continue to collect data . In this
respect blacked-out rules differ from disabled rules; data continues to
be collected and stored in the repository.

Blackout periods are enabled by entering the following URL into the
address bar of your browser, substituting the appropriate host name,
port and server name:

     http://LOCALHOST:18080/rest?command=blackout »
      &server_name=SUSE:3306&blackout_state=true

If you are unsure of the host name and port to use, check the
`configuration_report.txt' file. Be sure to specify the correct port
for the Tomcat server. Specify the server you wish to blackout using
the name that appears in the Server Tree, being sure to include a colon
and port number as shown in the preceding example.

An HTTP authentication dialog box requesting your Dashboard user name
and password will open. Specify the administrator's credentials. The
default user name is `admin'; use the password you specified when you
initially logged in to the Dashboard.

You can also blackout a server group by entering the following URL into
the address bar of your browser, substituting the appropriate host
name, and server group name:

     http://LOCALHOST:18080/rest?command=blackout »
      &group_name=FINANCE&blackout_state=true

When the HTTP authentication dialog box opens, enter the
administrator's credentials.

You can confirm that a server is blacked out by looking at the server
name in the Dashboard; the name of a blacked out server is greyed.

To reactivate the blacked-out server or server group, use the
appropriate URL and query string, changing the `blackout_state=true'
name/value pair to `blackout_state=false'. Again, this must be done by
a user with administrative privileges.

*Note*:

Restarting MySQL Enterprise Monitor will *not* reactivate a blacked out
server.


File: manual.info,  Node: mem-advisor-scripting-blackouts,  Prev: mem-advisor-blackouts,  Up: mem-advisor-blackouts

15.7.6.1 Scripting Blackouts
............................

Rather than opening your web browser and blacking out a server by
typing entries into the address bar, you can write a script to achieve
the same effect. This section documents a sample blackout script that
can be run from the command line.

Create the following file and save it as `blackout.pl'.

       #!/usr/bin/perl

       use LWP 5.64;

       # USAGE: blackout.pl servicemanager:18080 admin password servername:3306 true

       # $ARGV[0] = management server hostname:port
       # $ARGV[1] = management server username
       # $ARGV[2] = management server password
       # $ARGV[3] = mysqld managed instance server name and port
       # $ARGV[4] = blackout state (true/false)

       my $browser = LWP::UserAgent->new;
       $browser->credentials(
         $ARGV[0],
         '',
         $ARGV[1],
         $ARGV[2]
       );

       my $url = URI->new('http://'.$ARGV[0].'/rest');

       $url->query_form( # And here the form data pairs:
         'command' => 'blackout',
         'server_name' => $ARGV[3],
         'blackout_state' => $ARGV[4]
       );

       my $response = $browser->post( $url );

       if (!$response->is_success) {
         die $response->status_line . "\n";
       }

*Note*:

Windows users can omit the shebang line.

On Unix systems use the `chmod +x blackout.pl' command to make the file
executable.

At the command line enter blackout.pl SERVICEMANAGER:18080 admin
PASSWORD SERVERNAME:3306 true.

If you are unsure of the host name and port to use, check the
`configuration_report.txt' file. Be sure to specify the correct port
for the Tomcat server. Specify the server you wish to blackout using
the name that appears in the Server Tree, being sure to include a colon
and port number as shown in the preceding example. Make sure that the
user you specify is a "manager". Specifying a user with "dba" rights
only will not black out a server and no error will be displayed.

You can confirm that a server is blacked out by looking at the server
name in the Dashboard; the name of a blacked out server is greyed. To
end the blackout, run the same script, changing the final argument to
`false'.

*Note*:

Restarting MySQL Enterprise Monitor will *not* reactivate a blacked out
server.


File: manual.info,  Node: mem-events,  Next: mem-graphs,  Prev: mem-advisors,  Up: mem-introduction

15.8 The Events Page
====================

* Menu:

* mem-closing-events::           Closing an Event

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

Once an advisor has been scheduled, it will run at set intervals. If it
finds nothing of interest no alerts or emails will be created.

When alerts are triggered, they appear on the `Events' screen. Alerts
also appear on the `Monitor' screen in order of severity. The
notification group or groups associated with a specific rule receive
email notification when an alert is triggered. For more information
about creating notification groups see *Note mem-notification-groups::.

To view open events, click on the `Events' tab. The tree-view on the
left determines which server or server group these events belong to.
Open events are shown in tabular format.

FIGURE GOES HERE: MySQL Enterprise Dashboard: Events screen

The event table has the following columns:

   * `Severity' - An icon indicating the severity of the alert

   * `Server' - The name of the server the alert applies to

   * `Advisor' - The category of the advisor

   * `Rule' - A short description of the rule that has been violated

   * `Time' - The approximate time the event occurred

   * `Status' - The status of the event

   * `Unnamed Column' - Provides a link to the `Close' dialog box

By default, all events are shown but the list of events can be filtered
using the form displayed above the event list. The options include
filtering by:

   * Severity

   * Date

   * Advisor group

   * Specific rule

   * Status

Choose the options you are interested in and click the `filter' button
to refresh the display. You may limit the number of items that appear
on a page by choosing a different value from the `Limit' drop down
listbox.

The drop down list box showing severity has the options: `All',
`Alerts', `Critical', `Warning', `Info', `Success', and `Unknown'.
Selecting the option `All' shows all alerts and also those rules that
have run successfully. A successful rule is one that has not been
violated and is indicated by a star icon. `Alerts' shows only those
rules that have been violated.

Columns are sorted by clicking on the individual column headings.  The
alerts shown in *Note mem-events-screen::, are sorted by decreasing
severity. An octagonal red icon indicates a critical alert, a
triangular yellow icon a warning, and a conversation bubble an
informational alert. A star beside an event indicates that the rule has
run successfully and no alert created. A question mark icon indicates
that the status of the rule is unknown.

The server shown in *Note mem-events-screen::, is filtered for `All'.
Typically, when filtering by severity you would choose `Alerts' and, if
you see a `Critical', `Warning', or `Info' alert, use the `All' filter
to see when the rule last ran successfully. This may assist in
determining the cause of the alert.

Besides filtering for severity, you can also choose to filter for a
specific time period using the `From' and `To' text boxes. You also
have the choice of filtering by specific rules or categories of rules.
The `Status' drop-down list box let's you choose `All', `Open', or
`Closed' events. To avoid excessive scrolling, you can also limit the
number of events that show on a specific page.

For more information about an alert, click on the rule name. A pop-up
window will appear showing a description of the alert and the exact
time of occurrence. This pop-up windows provides links to useful
resources and advice for resolution. You can also view the exact
expression that generated the event.


File: manual.info,  Node: mem-closing-events,  Prev: mem-events,  Up: mem-events

15.8.1 Closing an Event
-----------------------

After determining what action to take, events should be closed.

To resolve an individual alert click the `close' link in the
`Operations/Notes' column. Document the resolution using the `Notes'
text area and choose the `close event(s)' button.

To close a number of alerts simultaneously, select the checkbox beside
the alerts you wish to close and then click the `close' button to the
lower or upper left side of the screen.

Once an event has been closed it appears on the `Events' screen showing
a `resolution notes' link. Click this link to review the notes. Events
that have been closed are saved in the Repository. If you wish to view
closed events filter the display by choosing `Closed' from the `Status'
drop-down box.


File: manual.info,  Node: mem-graphs,  Next: mem-query-analysis,  Prev: mem-events,  Up: mem-introduction

15.9 The Graphs Page
====================

* Menu:

* mem-available-graphs::         Displaying Graphs
* mem-setting-graph-interval::   Setting an Interval
* mem-setting-graph-time-span::  Setting a Time Span

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

Navigate to the `Graphs' page by choosing the `Graphs' tab.

By default four graphs are displayed on the `Monitor page'. These
graphs present information about the currently selected server or
server group, showing the hit ratios, CPU utilization, connections, and
database activity. Color coding helps distinguish different aspects of
each graph.

From the `Monitor' page you can make permanent or temporary changes to
the way a graph is displayed. For example, you can choose to display
the last hour's activity or you can choose to view a specific period of
time.

Persistent changes to the way the graphs display are only made from the
`Monitor' page. You can set the size of the thumbnails and the
full-sized graphs and you can also set their refresh interval. For more
information, see *Note mem-monitor-page-graphs::. As with the `Monitor'
page, the data shown in the graphs is determined by the server or group
of servers selected in the server tree.

The `Graphs' page shows all the available graphs and provides the
capability of adjusting the scale of the graphs, allowing a more or
less detailed view as the situation requires. To ensure that you have
the latest versions of the various graphs click on the `Check For
Updates' link on the top left of this page.


File: manual.info,  Node: mem-available-graphs,  Next: mem-setting-graph-interval,  Prev: mem-graphs,  Up: mem-graphs

15.9.1 Displaying Graphs
------------------------

The total number of graphs varies depending upon your subscription
level. The four graphs that appear by default on the `Monitor' page are:

   * Hit Ratios

   * Database Activity

   * Connections

   * CPU Utilization

When the `Graphs' page is first opened, no graphs are visible. To view
a graph click the `+' button on the left or, to view all graphs, use the
`expand all' button.

The larger size of graphs is the primary reason for viewing graphs on
the `Graphs' page rather than on the `Monitor' page. Additionally, you
can only show a maximum of six graphs on the `Monitor' page; the
remaining graphs can only be viewed from the `Graphs' page.


File: manual.info,  Node: mem-setting-graph-interval,  Next: mem-setting-graph-time-span,  Prev: mem-available-graphs,  Up: mem-graphs

15.9.2 Setting an Interval
--------------------------

Change the interval for a graph by choosing values from the `Hours' and
`Minutes' drop-down list boxes. If necessary adjust the width and
height of the graph and then click the `update' button.  The changes to
the time span apply to all the graphs on the `Graphs' page but have _no_
effect on the graphs on the `Monitor' page.

To change the graphs both here and on the `Monitor' page use the
`configure graphs' link on the top right. This opens a dialog box for
setting the default interval for the x-axis. Save any changes that you
have made and the values chosen will be the defaults whenever you log
in. You can also change the defaults from the `Monitor' page as
described in *Note mem-monitor-page-graphs::; defaults for other users
will be unchanged.

Use the `reset' button to restore the default value for the interval.
Doing this will also reset the default size of the graphs.


File: manual.info,  Node: mem-setting-graph-time-span,  Prev: mem-setting-graph-interval,  Up: mem-graphs

15.9.3 Setting a Time Span
--------------------------

Setting a graph to display a time span gives you a historical
perspective on server activity. You may want to know what was happening
at a specific point in time or you may wish to look at an extended
period in order to determine patterns or trends.  Changing the time
span gives you the flexibility to do this.

In the `Time Display' drop-down list box select the `From/To' option.
Choosing this option updates the display to include `To' and `From'
text boxes.

Set the date you wish to start viewing from by manually entering the
date in year, month, and day format (2007-03-14). However, it is much
easier to click the calendar icon and choose a date from the drop-down
calendar. Enter a terminating date in the same way.  If you wish, you
may also choose the specific time of day by selecting the hour and
minute.

If necessary adjust the width and height of the graph and then click
the `update' button. The changes to the time span apply to all the
graphs on the `Graphs' page but have _no_ effect on the graphs on the
`Monitor' page. You cannot change the time span of the graphs that
appear on the `Monitor' page.  Changes apply only to the current user;
defaults for other users will be unchanged.

Use the `reset' button to cancel your changes.


File: manual.info,  Node: mem-query-analysis,  Next: mem-replication,  Prev: mem-graphs,  Up: mem-introduction

15.10 The Query Analyzer Page
=============================

* Menu:

* mem-query-analysis-enabling::  Enabling Query Analyzer
* mem-query-analysis-queries::   Getting Detailed Query Information
* mem-query-analysis-filtering::  Filtering Query Analyzer Data
* mem-query-analysis-using::     Using Query Analyzer Data
* mem-query-analysis-troubleshooting::  Troubleshooting Query Analyzer
* mem-query-analysis-settings::  Query Analyzer Settings

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

Query Analyzer enables you to monitor the statements being executed on
a monitored server and retrieve information about the query, number of
executions and the execution times of each query. Queries are
normalized, so that the unique data defined within each query has been
removed. By removing the data specific elements of the queries, the
generic queries can be counted and identified more easily.

*Important*:

After this release is pronounced Generally Available, the MySQL Agent
will be ready for use in your production systems; however, we strongly
recommend reading these guidelines before using/deploying MySQL Query
Analyzer.

MySQL Query Analyzer is designed to gather query performance
information from a variety of sources. In this initial release, Query
Analyzer uses a new agent plug-in to proxy your queries and collect
performance data that is then transmitted to the Enterprise Monitor.
This is a new role for the Agent: it is no longer just monitoring, it
is now *optionally* between your application and the mysql server.

Depending upon your system load, it is possible to overload the proxy
or have the proxy/agent consume system resources needed by mysql
itself. In particular, the memory needed by the MySQL Agent for basic
monitoring is fairly small and consistent and depends on the number of
rules you have enabled. However, when the Query Analyzer is enabled,
the Agent can use significantly more memory to monitor and analyze
whatever queries you direct through it. In this case, the amount of
memory used depends on the number of unique normalized queries, example
queries and example `EXPLAIN's being processed plus the network
bandwidth required to send this query performance data to the Service
Manager. In general, the amount of memory used for the Query Analyzer
is well-bounded, but under heavy load or, in some cases under older
versions of linux, RAM usage by Query Analyzer may be too high for your
environment and load.

Therefore we advise you to use this initial release of Query Analyzer
extensively in development, test and stage environments under load for
an extended period of time before considering usage in a production
environment. For all deployments:

  1. We recommend carefully monitoring the Agent's resource consumption
     using the new graph `Memory Usage - Agent' graphs available on the
     `Graph' tab. You can also add an SMTP or SNMP notification to the
     new Heat Chart rule `MySQL Agent Memory Usage Excessive'.

  2. If the amount of memory consumed is too high, consider sampling
     queries during non-peak hours or monitoring only a subset of
     queries on this system.

If you experience any problems with Query Analyzer, we're interested in
working with you closely and quickly to resolve them. Please open a
Support issue right away. We're already working hard on optimizing
Agent/proxy RAM usage and are planning a series of rapid releases to
quickly distribute these and other improvements to you.

Query Analyzer works by intercepting the SQL statements that your
client application sends to the MySQL server. Instead of connecting
direct to the MySQL Server, queries are routed through the MySQL
Enterprise Monitor Agent, the agent/proxy forwards the queries on to the
server and sends the replies back to the client application as normal.
In addition to forwarding the queries, the agent/proxy will also
normalize the queries and then supply the execution information about
each query to the monitor. The forwarding functionality is provided by
the same module that supports the MySQL Proxy application. For
information on MySQL Proxy, see *Note mysql-proxy::.

*Important*:

The MySQL Proxy component, and Query Analyzer, require that clients
connecting through MySQL Enterprise Monitor Agent are using MySQL 5.0 or
later. Clients that use the library provided with MySQL 4.1 or earlier
will not work with MySQL Enterprise Monitor Agent.

Once your application has been configured to communicate via the MySQL
Enterprise Monitor Agent, queries will be monitored and the simplified
queries, without the query specific data, will be sent to the MySQL
Enterprise Monitor Agent.

There are a number of different ways that you can enable Query
Analysis. For more information on the different options, see *Note
mem-query-analysis-enabling::.

To analyse the queries captured by the agent/proxy, change to the
`Query Analyzer' page. You can see an example of the table on that page
in the figure below.

FIGURE GOES HERE: MySQL Enterprise Dashboard: Query Analyzer

The main Query Analyzer table provides the summary information for all
of the queries executed via the agent/proxy. The table will track all
the queries submitted to the server via the agent/proxy.  The table
will show a maximum of 20 rows, and you can page through the list of
queries by using the page numbers, or the `next', `previous', `first',
and `last' buttons.  To filter the list of queries that are displayed,
or to change the number of queries, see *Note
mem-query-analysis-filtering::.

Each row within the table provides the statistical information for one
normalized query statement. If you have configured multiple
agent/proxies to accept and forward queries to different servers, then
you can expand the server view. The summary information displayed is
different depending on whether you have selected a server group or an
individual server.

If you have selected a server group, then the information displayed is
aggregated from across the entire group. The same query executed on
multiple servers will show average, total and minimum/maximum
information for that query across all the servers. If you select an
individual server, then only queries executed on that server are
included within the table.

For each row, the following columns are populated according to the
selected filtering options. For example, if the filter have been
configured to show queries within the last 30 minutes (`Interval'),
then only queries executed during that time will be displayed, and the
corresponding statistics, such as execution times, rows returned and
bytes returned will be according to that 30 minute timespan.

   * `Query' -- the normalized version of the query. Normalization
     removes the query-specific data so that different queries with
     different data parameters are identified as the same basic query.

     The information is shown as one query per row. Each query row is
     expandable, and can be expanded to show the execution times for
     individual servers for that query.

   * `Database' -- the name of the database used in the query. The
     column may be blank if the database name has not been explicitly
     stated within the query.

   * `Exec Count' -- the number of times that the query has been
     executed.

   * `Exec Time' -- the execution time for all the matching queries.
     This is the time, for every invocation of the corresponding query,
     as calculated by comparing the time when the query was submitted
     and when the results were returned by the server. Times are
     expressed in HH:MM::SS.MS (hours, minutes, seconds, and
     milliseconds).

     The `Execution' column is further subdivided into the following
     columns:

        * `Count' -- the total number of executions.

        * `Total' -- the cumulative execution time for all the
          executions of this query.

        * `Max' -- the maximum execution time for an execution of this
          query.

        * `Avg' -- the average execution time for the execution of this
          query.

     When looking at the information provided in this query, you should
     consider comparing the average and maximum execution times to see
     if there was a problem on a specific server or during a specific
     time period when the query took place, as this may indicate an
     issue that needs to be investigated. For more information, see
     *Note mem-query-analysis-using::.

   * `Rows' -- the rows returned by the query. The column is
     sub-divided into the following columns:

        * `Total' -- the sum total number of rows returned by all
          executions of the query.

        * `Max' -- the maximum number of rows returned by a single
          execution of the query.

        * `Avg' -- the average number of rows returned by all
          executions of the query.

   * `Bytes' -- the number of bytes returned by each query. The column
     is sub-divided into the following columns:

        * `Total' -- the sum total bytes returned by all executions of
          the query.

        * `Max' -- the maximum number of bytes returned by a single
          execution of the query.

        * `Avg' -- the average number of bytes returned by all
          executions of the query.

   * `First Seen' -- the first time the query was seen within the given
     filter conditions.

You can sort the list of queries by clicking on the column name. The
direction of the sort (highest to lowest, or lowest to highest) is
indicated by a triangle next to the currently selected column. The
default is to sort the list of queries by the Total Execution time.


File: manual.info,  Node: mem-query-analysis-enabling,  Next: mem-query-analysis-queries,  Prev: mem-query-analysis,  Up: mem-query-analysis

15.10.1 Enabling Query Analyzer
-------------------------------

* Menu:

* mem-query-analysis-enabling-app::  Enabling Query Analyzer by Changing the Application
* mem-query-analysis-enabling-mysql::  Enabling Query Analyzer by Changing MySQL Server

There are three different ways of enabling query analyzer:

   * Change your application to talk to the Proxy port you configured
     during installation. This requires changing your application code,
     and may require that you stop and restart you application, but
     does not require any changes to your MySQL server. For more
     information, see *Note mem-query-analysis-enabling-app::.

   * Change your MySQL server to listen on a different port, and
     configure the Agent/proxy to listen on the original MySQL server
     port. This does not require any changes to your application, but
     will require shutting down and restarting your MySQL server, which
     may affect your cache and performance. For more information, see
     *Note mem-query-analysis-enabling-mysql::.

   * Use IP tables to redirect the network packets to the agent/proxy.

*Important*:

After this release is pronounced Generally Available, the MySQL
Agent/proxy will be ready for use in your production systems; however,
we strongly recommend reading these guidelines before using/deploying
MySQL Query Analyzer.

MySQL Query Analyzer is designed to gather query performance
information from a variety of sources. In this initial release, Query
Analyzer uses a new agent plug-in to proxy your queries and collect
performance data that is then transmitted to the Enterprise Monitor.
This is a new role for the Agent: it is no longer just monitoring, it
is now *optionally* between your application and the mysql server.

Depending upon your system load, it is possible to overload the proxy
or have the proxy/agent consume system resources needed by mysql
itself. In particular, the memory needed by the MySQL Agent for basic
monitoring is fairly small and consistent and depends on the number of
rules you have enabled. However, when the Query Analyzer is enabled,
the Agent can use significantly more memory to monitor and analyze
whatever queries you direct through it. In this case, the amount of
memory used depends on the number of unique normalized queries, example
queries and example `EXPLAIN's being processed plus the network
bandwidth required to send this query performance data to the Service
Manager. In general, the amount of memory used for the Query Analyzer
is well-bounded, but under heavy load or, in some cases under older
versions of linux, RAM usage by Query Analyzer may be too high for your
environment and load.

Therefore we advise you to use this initial release of Query Analyzer
extensively in development, test and stage environments under load for
an extended period of time before considering usage in a production
environment. For all deployments:

  1. We recommend carefully monitoring the Agent's resource consumption
     using the new graph `Memory Usage - Agent' graphs available on the
     `Graph' tab. You can also add an SMTP or SNMP notification to the
     new Heat Chart rule `MySQL Agent Memory Usage Excessive'.

  2. If the amount of memory consumed is too high, consider sampling
     queries during non-peak hours or monitoring only a subset of
     queries on this system.

If you experience any problems with Query Analyzer, we're interested in
working with you closely and quickly to resolve them. Please open a
Support issue right away. We're already working hard on optimizing
Agent/proxy RAM usage and are planning a series of rapid releases to
quickly distribute these and other improvements to you.

Note that you must have enabled Query Analyzer within the agent/proxy
during installation. If you did not enable Query Analyzer during the
installation of the agent/proxy, check the following elements within
the main `mysql-monitor-agent.ini' configuration file:

   * Add the `proxy' plugin to the `plugins' parameter:

          plugins=proxy,agent

   * Ensure that the `quan.lua' items file is enabled in the
     `agent-item-files' configuration property:

          agent-item-files = share/mysql-proxy/items/quan.lua,share/mysql-proxy/items/items-mysql-monitor.xml

   * Check and set the `proxy-address', `proxy-backend-addresses', and
     `proxy-lua-script' settings are configured:

          proxy-address=:4040
          proxy-backend-addresses = 127.0.0.1:3306
          proxy-lua-script        = share/mysql-proxy/quan.lua

For more information on these configuration options, see *Note
mem-cfg-mysql-monitor-agent-ini::.

*Note*:

The Query Analyzer functionality may show as being enabled on a server,
even though the modules within MySQL Enterprise Monitor Agent may not
have been enabled.

You may also need to make some additional changes to the security
configuration on your server to ensure that queries are correctly
reported to MySQL Enterprise Service Manager:

   * You must ensure that each user configured within your application
     that connects through the agent/proxy and is required to report
     query analyzer information is allowed to connect to the server
     from the host on which the agent/proxy is running. When the user
     connects to the agent/proxy, and the agent/proxy connects to the
     server the host of the agent/proxy will be used as the identifying
     client host name during the connection.

     To update your user credentials, you need to use the `GRANT'
     statement. For example:

          mysql> GRANT SELECT,UPDATE,INSERT on database.* to 'user'@'localhost' IDENTIFIED BY 'password';

   * The application user must have `SELECT' privileges on the
     `mysql.inventory' table.  This table contains the server UUID and
     is required to report the query analyzer data to the MySQL
     Enterprise Service Manager. To enable this, use the `GRANT' option:

          mysql> GRANT SELECT on mysql.inventory to 'user'@'localhost' IDENTIFIED BY 'password';


File: manual.info,  Node: mem-query-analysis-enabling-app,  Next: mem-query-analysis-enabling-mysql,  Prev: mem-query-analysis-enabling,  Up: mem-query-analysis-enabling

15.10.1.1 Enabling Query Analyzer by Changing the Application
.............................................................

Generally, changing your application is the easiest and recommended
method. For example, given a typical structure like the one shown in
the figure below, the client application would need to be modified so
that it no longer communicated directly with the MySQL server, but to
the agent/proxy.

FIGURE GOES HERE: MySQL Enterprise Dashboard: Standard agent/monitor
topology

You can see an example of the structure when communicating via the
agent/proxy below.

FIGURE GOES HERE: MySQL Enterprise Dashboard: Query Analyzer
agent/monitor topology

To enable query analyzer within your application:

  1. Make sure that the MySQL Enterprise Service Manager and your MySQL
     Enterprise Monitor Agent are configured and running.

  2. Confirm the configuration of your agent by examining the contents
     of the `etc/mysql-monitor-agent.ini' file within your installed
     Agent directory.

     Queries will be sent to the host specified in the
     `proxy-backend-addresses' parameter, and the agent will listen for
     connections to be redirected to the server on the host name and
     port configured in the `proxy-address' parameter.

  3. Now modify your client application to communicate with the address
     specified in the `proxy-address' parameter.

     Alternatively, if you do not want to modify your application
     directly, you can use iptables or firewall rules to redirect
     queries from the original host/port combination to the agent's
     port.

     Because connections to the MySQL server will be coming from the
     agent/proxy, not the original host, the user credentials used must
     be have a suitable `GRANT' statement for connections from
     `localhost', or the host on which the agent/proxy is executing.
     The user name and password information will be passed on directly
     through the agent/proxy from the client to the server.

  4. Confirm that your application still operates normally. There
     should be no difference between communicating directly with the
     MySQL server and communicating via the agent/proxy.

*Note*:

If you are using the *Note `mysql': mysql. client to connect to the
agent/proxy and your backend servers, make sure that you are
communicating with the proxy over the right port.  By default, if you
specify `localhost' as the host name, then *Note `mysql': mysql. will
connect using the local Unix domain socket, rather than the TCP/IP
socket.

You can enforce *Note `mysql': mysql. to use the right port either by
explicitly requesting the protocol type, or by using the IP address
rather than `localhost'. For example, both of these command lines will
start the client using the right protocol:

     shell> mysql --port=4040 --protocol=tcp
     shell> mysql --port=4040 --host=127.0.0.1

*Note*:

It is recommended that you use one agent/proxy per MySQL server
instance. The agent/proxy is not able to forward queries to multiple
MySQL server backends.


File: manual.info,  Node: mem-query-analysis-enabling-mysql,  Prev: mem-query-analysis-enabling-app,  Up: mem-query-analysis-enabling

15.10.1.2 Enabling Query Analyzer by Changing MySQL Server
..........................................................

When enabling Query Analyzer by changing the MySQL Server, you need to
shutdown your server, edit the MySQL configuration file, and then
restart MySQL. You will also need to change your Agent/proxy
configuration so that the Agent/proxy is listening on the original
MySQL TCP/IP port. To use this method:

  1. Edit the `/etc/my.cnf' or other MySQL configuration file and
     change or add the `port' setting from it's current value (default
     3306), to another value. For example:

          port                                            = 3307

  2. Shutdown your MySQL Server.

  3. Startup your MySQL Server and confirm that is running.

  4. Edit your MySQL Enterprise Monitor Agent configuration so that the
     agent/proxy is listening for connections on the original MySQL
     port:

          proxy-address=:3306
          proxy-backend-addresses = 127.0.0.1:3307

  5. Stop and restart MySQL Enterprise Monitor Agent.

You should now be able to connect to your MySQL server through the
MySQL Enterprise Monitor Agent by connecting on the original port:

     shell> mysql --host=127.0.0.1


File: manual.info,  Node: mem-query-analysis-queries,  Next: mem-query-analysis-filtering,  Prev: mem-query-analysis-enabling,  Up: mem-query-analysis

15.10.2 Getting Detailed Query Information
------------------------------------------

If you click on an individual query, a pop-up window will provide more
detailed information about the individual query. You can see an example
of this in the figure below. The available tabs within this window will
depend on whether you have configured the more detailed query
information. By default, you will always be provided the Summary
Details page. If enabled, you may also view Example Details, which
provide more detailed data about a specific query, including the data
and parameters submitted. In addition, you may also enable Example
Explain, which provides you with the ability to remotely execute an
`EXPLAIN' statement with the specified query and view the resulting
information.

   * The *Canonical Query* tab:

     FIGURE GOES HERE: MySQL Enterprise Dashboard: Canonical Query Tab
     for a Query

     In addition to the summary information given in the table, you
     will get detailed execution statistics, including the minimum
     time, maximum time, average time, total time and the standard
     deviation. The standard deviation will enable you to determine
     whether a particular invocation of a query is outside the normal
     distribution of times for the given query.

     Row statistics provide more detailed contents on the maximum,
     minimum, average, total, and standard deviation for the number of
     rows returned by the query, and the total size and maximum size of
     the data returned. The time period for the total and average
     figures is shown under the Summary Time Span.

     The detailed view for a query also provides three different views
     of the query. The `truncated' version is a shortened version of
     the query. The `full' version of the query is the entire query
     statement. Normalization removes the constants from the individual
     queries so that queries following the same logical structure are
     identified as the same basic query.

     To close the query detail window, click the `Hide' button.

     To simplify the identification of a given query, you can create a
     query alias. The alias will be used in place of the normalized
     query text within the Query Analyzer table. To create an alias for
     a query, click the `create alias' link against the query. The
     maximum length for a query alias is 255 characters.

   * The *Example Query* tab:

     FIGURE GOES HERE: MySQL Enterprise Dashboard: Example Query Tab
     for a Query

     The Example Details tab provides detailed information about the
     most expensive query executed, as determined by the execution time.

     In addition to the full query, with data, that was executed, the
     tab shows the execution time, data, user, thread ID, client host
     and execution host for the given query.

   * The *Explain Query* tab:

     FIGURE GOES HERE: MySQL Enterprise Dashboard: Explain Query Tab
     for a Query

     The Example Explain tab enables you to view the output from
     running the query with the `EXPLAIN' prefix.  For more
     information, see *Note explain::.


File: manual.info,  Node: mem-query-analysis-filtering,  Next: mem-query-analysis-using,  Prev: mem-query-analysis-queries,  Up: mem-query-analysis

15.10.3 Filtering Query Analyzer Data
-------------------------------------

You can filter the queries shown within the Query Analyzer table by
using the form at the top of the table. The different fields of the
form are used to specify the parameters for the filter process. Once
you have specified a filter, all the queries and related statistics
shown within the Query Analyzer table are displayed in relation to the
filter settings. For example, by default, the filter settings show the
queries for the last 30 minutes. All the statistics shown are relative
to the last 30 minutes, including average, maximum and execution counts.

The filter fields are:

   * `Search Type' and `Query Search' support text searching of the
     normalized query. For the search type you can specify either a
     basic text match, or a regular expression match. In addition to
     the basic text match, you can also search for a query that does not
     contain a particular string. For regular expression searches, you
     can specify whether the regular expression should match, or not
     match (negative regexp) the queries. Regular expressions are
     parsed using the standard MySQL `REGEXP()' function. For more
     information, see *Note regexp::.

     *Note*:

     The search is performed against the canonical version of the
     query. You cannot search against specific text or values within
     the parameters of the query itself.

   * `Database' -- limit the queries to those executed within a
     specific database. The database match is performed using the
     `LIKE' match from the MySQL database, hence you can use the `%' and
     `_' characters to multiple and single character matches. For more
     information, see *Note pattern-matching::.

   * The `Time Display' menu selects whether the time selection for
     filtering should be based on the time `interval' (only queries
     recorded within the displayed time period are shown, using the
     `Hours' and `Minutes' popup), or whether the selection should be
     based on a time period (`From/To'), where you can select the time
     range to be displayed.

     Using the `Interval' mode shows queries within the given time
     period from the point the graph was updated. For example, if you
     select 30 minutes, then the queries shown were captured within the
     last 30 minutes. If you updated the display at 14:00, then the
     queries displayed would have been captured between 13:30 and
     14:00. Using interval mode limits the timespan for the filter
     selection to a maximum of 23 hours and 59 minutes.

     Using the `From/To' mode enables you to show queries between
     specific dates and times. Using this mode you can show only the
     queries received during a specific time span, and you can display
     the query history for a much longer time period, for as long as
     you have been recording query analysis information.

   * The `View' selection determines whether the information should be
     returned on a group basis, where an aggregate of the same query
     executed on all monitored servers is shown, or on a `Server'
     basis, where queries are summarized by individual server. If the
     latter option has been selected, the table includes an additional
     column showing the server.

   * `Query Type' lets you select the type of query on which to filter
     queries. Selecting `All' will show all queries. Additional query
     types you can select include `SELECT', `INSERT', `UPDATE' and other
     main SQL query types.

   * `Limit' specifies the number of queries to be displayed within
     each page.

When you have set your filter parameters, you can update the Query
Analysis display by clicking the `filter' button. To reset the fields
to the default settings click the `reset' button.


File: manual.info,  Node: mem-query-analysis-using,  Next: mem-query-analysis-troubleshooting,  Prev: mem-query-analysis-filtering,  Up: mem-query-analysis

15.10.4 Using Query Analyzer Data
---------------------------------

The information provided by Query Analyzer can be complex to understand
and resolve into simple targets and resolutions for your application.
The information can be used in different ways to find problems in your
queries or your servers, or both. Provided below are some tips on how
to get the best out of the Query Analysis interface, and how to
identify different queries and problems based on the information shown
by the Query Analyzer system.

First, consider the information provided by individual columns by your
queries. In particular, the following columns can highlight specific
problems with your queries or database server:

   * *Execution Count* -- High execution counts, especially for a query
     that you expect to be executed very rarely, may indicate that your
     application is either running a simple query to frequently, or may
     be running a query multiple times that could otherwise be cached.
     You should pay particular attention to queries where the execution
     count increases significantly in a short period of time compared
     to the normal execution rate.

     *How to find:* Use the sort feature to sort the queries by
     execution count.

   * *New queries* -- new queries appearing in the Query Analyzer tab,
     especially if they appear after other queries have been in the
     display for a number of hours or days may indicate a number of
     issues:

   * *Execution times* -- long execution times, and a long max
     execution time compared to the average execution time may indicate
     a problem with a specific query and specific parameters.

     *How to find:* Use the sort feature to sort the queries by
     execution count.

You can also use the filtering and sort options to get specific
information about potential problem queries.


File: manual.info,  Node: mem-query-analysis-troubleshooting,  Next: mem-query-analysis-settings,  Prev: mem-query-analysis-using,  Up: mem-query-analysis

15.10.5 Troubleshooting Query Analyzer
--------------------------------------

If you are having trouble with Query Analyzer, either because the
information is not being shown or the full range of queries that you
expect are not appearing in the Query Analyzer page then there are a
number of systems you can check.

To confirm that your system is correctly configured for Query Analysis,
check the following:

   * Confirm that the agent is running by checking the Agent log and
     the status of the server within MySQL Enterprise Service Manager

   * Check the configuration of the agent. You must confirm the
     following:

        * The `plugins' parameter within the main configuration file,
          `mysql-monitor-agent.ini', must contain the `proxy' plugin:

               plugins=proxy,agent

        * The `agent-item-files' parameter within the main
          configurationfile, `mysql-monitor-agent.ini', must specify
          the `share/mysql-proxy/items/quan.lua' script:

               agent-item-files = share/mysql-proxy/items/quan.lua, »
                    share/mysql-proxy/items/items-mysql-monitor.xml

        * The proxy configuration parameters must point to the MySQL
          server where you want your queries to be sent. For example,
          if you are running your agent on the same host as your MySQL
          server then you might have the following lines in your
          `mysql-monitor-agent.ini' file:

               proxy-address=:4040
               proxy-backend-addresses = 127.0.0.1:3306
               proxy-lua-script        = share/mysql-proxy/quan.lua

          The above configuration can means:

             * The agent/proxy will listen on the current machine,
               using port 4040 (`proxy-address').

             * The agent/proxy will send all queries received on to the
               host `127.0.0.1' on port `3306' (the standard MySQL
               port), as per the `proxy-backend-addresses' parameter.

     You can see a sample complete configuration file
     (`mysql-monitor-agent.ini'), using the `127.0.0.1' as the MySQL
     backend server, and reporting to a MySQL Enterprise Service
     Manager called `monitor':

          [mysql-proxy]
          plugins=proxy,agent
          agent-mgmt-hostname = http://agent:password@monitor:18080/heartbeat
          mysqld-instance-dir= etc/instances
          agent-item-files = share/mysql-proxy/items/quan.lua,share/mysql-proxy/items/items-mysql-monitor.xml
          proxy-address=:4040
          proxy-backend-addresses = 127.0.0.1:3306
          proxy-lua-script        = share/mysql-proxy/quan.lua
          agent-uuid = a3113263-4993-4890-8235-cadef9617c4b
          log-file = mysql-monitor-agent.log
          pid-file=/opt/mysql/enterprise/agent/mysql-monitor-agent.pid

   * Confirm that you can connect through the agent proxy to your
     backend MySQL server. You can do this by checking with the MySQL
     client. You must specify the same options as you would if you were
     connecting to the original server, including specifying the same
     user and password information:

          shell> mysql -h 127.0.0.1 --port 4040 --user=root -p
          Enter password:
          Welcome to the MySQL monitor.  Commands end with ; or \g.
          Your MySQL connection id is 299239
          Server version: 5.0.60-log Gentoo Linux mysql-5.0.60-r1
          Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
          mysql>

   * Check that your application is configured to use the configured
     proxy port, instead of the real MySQL port when sending queries.

   * Confirm that Query Analyzer enabled for your host. For more
     information, see *Note mem-query-analysis-settings::.


File: manual.info,  Node: mem-query-analysis-settings,  Prev: mem-query-analysis-troubleshooting,  Up: mem-query-analysis

15.10.6 Query Analyzer Settings
-------------------------------

There are a number of settings related to the Query Analyzer data.  You
can configure the query analyzer operation by using the `configure
query analyzer' link within the `Query Analyzer' tab, or through the
`configure query analyzer' button within the `Manage Servers' tab
within the `Settings' tab. Both methods provide you with the same
dialog:

FIGURE GOES HERE: MySQL Enterprise Dashboard: Query Analyzer
Configuration

Through either solution, the configuration options that you select are
applied to the individual server or server group selected within the
`Servers'navigation panel.

There are three configuration options available through either method:

   * `Enable Query Analyzer' configures whether query analyzer should
     be enabled for this server or server group. If selected, query
     analyzer will be enabled. To disable, delect the check box.

     If Query Analyzer has been enabled, then you can additional
     configure the Example Query function by selecting the `Enable
     Example Query' checkbox. Enabling this option provides an
     additional tab when you open the `Canonical Query' window when
     clicking on a query.

   * `Enable Example Query' allows the Query Analyzer to display more
     information about individual queries.  When enabled, queries and
     their data items (rather than the canonical form shown by default)
     will be provided. Enabling this option may expose the full query
     statements and therefore may present a security issue.

     With the `Example Query' option enabled, an additional tab within
     the query summary details is made available. For more information,
     see *Note mem-query-analysis-queries::.

     If you have enabled `Example Query', then you can additional
     enable `Example Explain', To enable this tab, select the `Enable
     Example Explain' checkbox.

   * `Enable Example Explain' provides another tab when viewing a query
     where you can view the output from `EXPLAIN' output from MySQL for
     the selected query. This will show the full query and how the
     query was executed within the servers.

     Enabling this option may add additional overhead to the execution
     of your server, as the server will run an `EXPLAIN' statement each
     time it identifies a long running query. For more information,
     *Note mem-faq::.

To enable or disable query analyzer for an individual server, go to the
`Settings' page and click on the `Manage Servers' link. To configure
all the properties, click the `configure query analyzer' link next to
server you want modify.

Alternatively, for each server, the `Query Analyzer' column shows the
current setting, On or Off, and whether the `Example' and `Explain'
functionality is enabled. To change any setting, click on the current
status to toggle between the On/Off position.

To disable or enable Query Analyzer for the selected servers, use the
`disable query analyzer' or `enable query analyzer' buttons within the
`Settings' page. You must have selected one or more servers from the
list of available servers before selecting these buttons.

You can use the options that you have just selected as the default for
all new servers that register with MySQL Enterprise Service Manager by
using select the `Make this the default for all new servers' checkbox.
By default, when a new server registers with MySQL Monitor, the server
is automatically configured to supply Query Analysis data. This can
have impact on the performance of your monitor and agent as it
increases the amount of information supplied to the MySQL Monitor.

Configuration of Query Analyzer occurs through the `configure defaults'
button from within the `Query Analyzer' page.


File: manual.info,  Node: mem-replication,  Next: mem-faq,  Prev: mem-query-analysis,  Up: mem-introduction

15.11 The Replication Page
==========================

* Menu:

* mem-replication-details::      Replication Page Details

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

Navigate to the `Replication' page by choosing the `Replication' tab.
This page provides a quick summary view of the state of your
replication servers or, if you wish, you can drill down and determine
specifics about any master or slave.

*Note*:

Servers, whether masters or slaves, must be monitored in order for them
to appear on this page.

*Note*:

There will be no `Replication' page if your subscription level does not
support this feature.

The `Replication' page groups all master servers with their slaves.
Masters and their slaves are autodiscovered and a grouping is created.
This grouping shows up on the replication page and also in the `Heat
Chart' on the `Monitor' page. Scans run on a five minute interval, so
depending upon the order of discovery, it can take as long as 2 polling
intervals to create a complete group.

FIGURE GOES HERE: MySQL Enterprise Dashboard: Replication groups

Discovery events are logged to the `Replication' log. To view this log
navigate to the `Settings' page and choose the `Logs' link. View all
replication-related events by clicking the `Replication' link. This log
can be a useful tool should you need to debug the replication topology
discovery process.

*Warning*:

The agent must be installed on the same machine as the server you are
monitoring in order for discovery to work properly. Do *not* use remote
monitoring.

Replication groups can be managed from the `Manage Servers' page in the
same way as other groups. However, any slaves removed from a server
group will automatically be restored to that group. It is also possible
to add non-slaves to a replication grouping. For more information about
server groupings see *Note mem-server-grouping::.


File: manual.info,  Node: mem-replication-details,  Prev: mem-replication,  Up: mem-replication

15.11.1 Replication Page Details
--------------------------------

Choose a value from the `refresh' drop-down list box to set the rate at
which information is updated. This refresh rate applies only to the
information presented on this page: It is independent of the rate set
for the `Monitor' page.

The following columns describe replication servers and their slaves:

   * Servers - Displays the group name and any master servers and slaves

   * Type - Indicates the topology of a server group or in the case of
     individual servers, whether a server is a master, a master/slave,
     or a slave

   * Slave IO - Reports the status of the slave IO thread

   * Slave SQL - Reports the status of the slave SQL thread

   * Seconds Behind - The number of seconds the slave is behind the
     master. This column is blank if a server is a master.

   * Binlog - The binlog file name

   * Binlog Pos - The current position in the binlog file

   * Master Binlog - The master binlog file name

   * Master Binlog Pos - The current position in the master binlog file

   * Last Error - The most recent error

   * Unlabeled Column - Use the `rename group' link on the server group
     line to edit the server group name

Levels of indentation in the `Servers' column show the relationship
between master servers and their slaves.  Most column headings are
active links that allow you to change the order of display by clicking
on the header. Sorting works differently for different column
groupings. Click the `Seconds Behind' header to order servers by the
number of seconds they are behind their master. However, in all cases,
the server topology is respected. For example, in a `TREE' topology,
ordering occurs within branches only.

If the agent is down, servers show in bold red in the `Servers' column.
The `Slave IO' and the `Slave SQL' columns display `stopped' in red
text if these threads are not running. If an agent is down, italics is
used to display the last know status of the IO or SQL threads.

Clicking on a master server opens a dialog box that displays
information about the server. The information shown includes:

   * The number of slave servers

   * The binlog file name

   * The binlog position

   * Which databases are replicated and which not

The dialog box also includes a link that allows the user to hide or
show the slave servers.

Clicking on a slave server opens a dialog window showing extensive
information about the slave.


File: manual.info,  Node: mem-faq,  Prev: mem-replication,  Up: mem-introduction

15.12 MySQL Enterprise Monitor Frequently Asked Questions
=========================================================

*Note*:

MySQL Enterprise subscription, MySQL Enterprise Monitor, MySQL
Replication Monitor, and MySQL Query Analyzer are only available to
commercial customers. To learn more, see:
http://www.mysql.com/products/enterprise/features.html
(http://www.mysql.com/products/enterprise/features.html).

FAQ Categories

   * *General Usage*

   * *MySQL Enterprise*

   * *MySQL Monitor*

   * *MySQL Query Analyzer*

*General Usage*

*Questions*
   * 15.12.1: While monitoring my network traffic I have noticed that
     the agents communicate information at irregular intervals to the
     MySQL Enterprise Service Manager. I cannot see anything in my
     configuration that would explain this behaviour. What is going on?

   * 15.12.2: How frequently is the data purge process executed?

   * 15.12.3: Does Query Analyzer work with all versions of MySQL and
     the MySQL Client Libraries?

   * 15.12.4: My MySQL Enterprise Service Manager is behind a firewall
     but it cannot communicate with the MySQL Enterprise website to
     register and download my license key and advisor bundle. I
     normally use a proxy service to access external websites. How do I
     configure the proxy settings for MySQL Enterprise Dashboard?

   * 15.12.5: What is the relationship between the advisor JAR file and
     the key?

   * 15.12.6: I have set the graphs to update every 5 minutes, and the
     page refresh to occur every minute. The page is refreshing
     correctly, but the graphs do not seem to update.

   * 15.12.7: Can the Trial-level key work with the Gold-level advisors
     JAR file?

   * 15.12.8: During query analysis, I am unable to obtain an `EXAMPLE'
     or `EXPLAIN' information when examining the detail of the analyzed
     query within the `Query Analyzer' panel.

   * 15.12.9: Does the Gold-level key support Silver-level advisors?

   * 15.12.10: I have enabled `EXPLAIN' queries for Query Analyzer, but
     no queries with the `EXPLAIN' data are showing up in the display.

   * 15.12.11: Can I run MySQL Enterprise Service Manager on machine
     with other applications running?

   * 15.12.12: Why do some rules appear to have a `Severity' of
     `Unknown'?

   * 15.12.13: How do I change the name of a server?

   * 15.12.14: I have started a Data Migration of my old data for a
     server to MySQL Enterprise Service Manager 2.0, but I have noticed
     that the performance of the monitor server has degraded
     significantly. Can I stop the migration?

*Questions and Answers* *15.12.1: ** While monitoring my network
traffic I have noticed that the agents communicate information at
irregular intervals to the MySQL Enterprise Service Manager. I cannot
see anything in my configuration that would explain this behaviour.
What is going on?  *

Each MySQL Enterprise Monitor Agent periodically sends information to
the server about a range of different information, including the core
rule and statistical data, Query Analyzer information and other data
used to monitor the status of your MySQL server.

One element of this is called the MySQL Enterprise Monitor Agent
Heartbeat, which is core information exchange that indicates that the
monitored server is still up and running. The heartbeat information is
vital because it tells the MySQL Enterprise Service Manager that the
agent and server are still communicating. This information is sent
regularly to the MySQL Enterprise Service Manager, but to prevent
multiple agents from sending the information at the same time, and
creating a large network load (or storm), the interval is randomized
with each heartbeat. The randomization ensures that the information is
still uploaded periodically, but without the potential to overload the
network with this data.

*15.12.2: ** How frequently is the data purge process executed?  *

A data purge process is started approximately once a minute. If you
have changed the purge period then the data will start to be purged
within the next minute.

*15.12.3: ** Does Query Analyzer work with all versions of MySQL and the
MySQL Client Libraries?  *

The MySQL Proxy component, and Query Analyzer, require that clients
connecting through MySQL Enterprise Monitor Agent are using MySQL 5.0 or
later. Clients that use the library provided with MySQL 4.1 or earlier
will not work with MySQL Enterprise Monitor Agent.

*15.12.4: ** My MySQL Enterprise Service Manager is behind a firewall
but it cannot communicate with the MySQL Enterprise website to register
and download my license key and advisor bundle. I normally use a proxy
service to access external websites. How do I configure the proxy
settings for MySQL Enterprise Dashboard?  *

To configure a proxy service, you need to edit the
`apache-tomcat/conf/catalina.properties' file within the MySQL
Enterprise Service Manager installation directory. To make the changes,
the proxy configuration information to the end of the file by setting
the `http.proxyHost' and `http.proxyPort' properties:

     http.proxyHost=proxy.example.com
     http.proxyPort=8080

You will need to restart the MySQL Enterprise Service Manager for the
change to take effect:

     shell> mysqlmonitorctl.sh restart

*15.12.5: ** What is the relationship between the advisor JAR file and
the key?  *

The JAR file contains graph and advisor definitions. The key file
contains typical customer validation data such as contract information,
number of servers covered, subscription level and dates.

*15.12.6: ** I have set the graphs to update every 5 minutes, and the
page refresh to occur every minute. The page is refreshing correctly,
but the graphs do not seem to update.  *

The graph refresh and page refresh are two different parameters.  The
graphs will update according to their refresh period, regardless of the
refresh period set for the main display page.

*15.12.7: ** Can the Trial-level key work with the Gold-level advisors
JAR file?  *

The Trial-level key can only be used with the Trial-level advisors JAR
file.

*15.12.8: ** During query analysis, I am unable to obtain an `EXAMPLE'
or `EXPLAIN' information when examining the detail of the analyzed query
within the `Query Analyzer' panel.  *

You must explicitly enable the `EXAMPLE' and `EXPLAIN' query
functionality. Make sure that you have enabled both panels. See *Note
mem-query-analysis-settings::.

*15.12.9: ** Does the Gold-level key support Silver-level advisors?  *

The Gold-level advisor JAR file will contain Silver-level advisors plus
Gold-level advisors. However, you cannot use the Gold-level key with
the Silver-level advisors JAR file. The Gold-level key can only be used
with the Gold-level advisors JAR file.

*15.12.10: ** I have enabled `EXPLAIN' queries for Query Analyzer, but
no queries with the `EXPLAIN' data are showing up in the display.  *

Query Analyzer only obtains `EXPLAIN' information when the MySQL
Enterprise Monitor Agent identifies a long running query. If none of
your queries exceed the defined threshold, then the `EXPLAIN'
information is not obtain and provided to the Query Analyze for display.

To change the query duration at which an `EXPLAIN' is triggered, you
must edit the `share/mysql-proxy/quan.lua' file within the MySQL
Enterprise Monitor Agent directory on each server. You need to change
the value configured in the `auto_explain_min_exec_time_us'. The
default is 500ms:

     ---
     -- configuration
     --
     -- SET GLOBAL analyze_query.auto_filter = 0
     if not proxy.global.config.quan then
             proxy.global.config.quan = {
                     analyze_queries  = true,   -- track all queries
                     query_cutoff     = 160,    -- only show the first 160 chars of the query
                     num_worst_queries = 5,
                     auto_explain     = true,
                     auto_explain_min_exec_time_us = 500 * 1000
             }
     end

The value is expressed in microseconds, which is why the value must be
multiplied by 1000. To reduce this value to 100ms you would modify the
line:

     auto_explain_min_exec_time_us = 100 * 1000

You do not need to restart MySQL Enterprise Monitor Agent for the
changes to take effect.

*15.12.11: ** Can I run MySQL Enterprise Service Manager on machine
with other applications running?  *

You can, but ideally you should be running your MySQL Enterprise
Service Manager on a dedicated machine, especially if you are
monitoring a number of different agents. For more information, see
*Note mem-deployment-config::.

*15.12.12: ** Why do some rules appear to have a `Severity' of
`Unknown'?  *

Due to timing issues, certain rules such as `32-Bit Binary Running on
64-Bit AMD Or Intel System' and `Key Buffer Size Greater Than 4 GB' do
not evaluate correctly due to timing issues. This is a known issue and
will be resolved in future versions of MySQL Enterprise Monitor.

*15.12.13: ** How do I change the name of a server?  *

Go to the `Manage Servers' panel within `Settings' and click `Rename
server'.

*15.12.14: ** I have started a Data Migration of my old data for a
server to MySQL Enterprise Service Manager 2.0, but I have noticed that
the performance of the monitor server has degraded significantly. Can I
stop the migration?  *

You can stop the migration of your historical data at any time.  Go to
the `Manage Servers' display of the `Settings' panel and click `Stop'
next to each server that is being migrated. You can restart the
migration at any point.

*MySQL Enterprise*

*Questions*
   * 15.12.1: How should I decide between MySQL Enterprise Basic,
     Silver, Gold and Platinum?

   * 15.12.2: What is MySQL Enterprise Server?

   * 15.12.3: How do I get a 30-day trial on MySQL Enterprise?

   * 15.12.4: Does MySQL Enterprise include Maintenance, Updates, and
     Upgrades?

   * 15.12.5: What is a Technical Account Manager?

   * 15.12.6: Are there any Webinars available?

   * 15.12.7: What is the pricing of MySQL Enterprise?

   * 15.12.8: Does MySQL Enterprise include Emergency Hot Fix Builds?

   * 15.12.9: Are there any MySQL Enterprise White Papers available?

   * 15.12.10: How do I buy MySQL Enterprise?

   * 15.12.11: What is MySQL Enterprise?

   * 15.12.12: Does MySQL provide IP (Intellectual Property)
     Indemnification?

   * 15.12.13: Can I buy MySQL Enterprise subscriptions for multiple
     years?

   * 15.12.14: What is MySQL Enterprise Unlimited?

   * 15.12.15: What is MySQL Production Support?

   * 15.12.16: Can I buy MySQL Enterprise subscriptions for only some
     of my production MySQL database servers?

   * 15.12.17: Are there any Demo/Tutorials available for MySQL
     Enterprise?

   * 15.12.18: Does MySQL Enterprise include 24x7 Technical Support?

   * 15.12.19: What if I plan to add more MySQL servers to my MySQL
     Enterprise subscription?

   * 15.12.20: What is the list of Supported Platforms?

   * 15.12.21: Do all my MySQL Enterprise subscriptions need to be at
     the same tier?

   * 15.12.22: What is MySQL Consultative Support?

*Questions and Answers* *15.12.1: ** How should I decide between MySQL
Enterprise Basic, Silver, Gold and Platinum?  *

MySQL Enterprise subscriptions are available in 4 tiers, providing you
the flexibility of choosing the capabilities and SLA that best meet
your requirements.  Learn More (/products/enterprise/features.html) If
you have questions and what to discuss your specific requirements,
please Contact MySQL Sales (/about/contact/sales.html?s=corporate)

*15.12.2: ** What is MySQL Enterprise Server?  *

MySQL Enterprise Server software is the most reliable, secure and
up-to-date version of MySQL for cost-effectively delivering E-commerce,
Online Transaction Processing (OLTP), and multi-terabyte Data
Warehousing applications. It is a fully integrated transaction-safe,
ACID compliant database with full commit, rollback, crash recovery and
row level locking capabilities. MySQL delivers the ease of use,
scalability, and performance that has made it MySQL the world's most
popular open source database.  Learn More
(/products/enterprise/server.html)

*15.12.3: ** How do I get a 30-day trial on MySQL Enterprise?  *

You can experience the MySQL Enterprise Monitor for 30 days by
registering to receive an email with login instructions.  Learn More
(/trials/enterprise)

*15.12.4: ** Does MySQL Enterprise include Maintenance, Updates, and
Upgrades?  *

Yes. As long as you have a valid contract for MySQL Enterprise, you
will receive all new MySQL Enterprise Server software releases
including Software Maintenance, Updates, and Upgrades.  The Software
Update Service will automatically notify you of the new releases.

*15.12.5: ** What is a Technical Account Manager?  *

MySQL Enterprise, at the Platinum tier, provides the option for a
Technical Account Manager (TAM). The TAM is your advocate within MySQL,
who proactively works to maximize your benefits from MySQL Support
Services.  Learn More (/products/enterprise/tam.html)

*15.12.6: ** Are there any Webinars available?  *

Yes. MySQL provides regularly scheduled Live Webinars.  Learn More
(/news-and-events/web-seminars/index.html) MySQL also provides
On-Demand Webinars to fit your schedule. These are recordings of
previously held Live Webinars that you can replay at any time.  Learn
More (/news-and-events/web-seminars/index.html)

*15.12.7: ** What is the pricing of MySQL Enterprise?  *

The pricing model for MySQL Enterprise is based on two key components:
per server and per year. MySQL Enterprise does not have artificial
restrictions based on CPUs, Memory, Machine Size, or Named Users. MySQL
Enterprise is available in 4 tiers (Basic, Silver, Gold and Platinum).
Choose the tier that best meets your requirements and budget.  Learn
More (/products/enterprise/features.html)

*15.12.8: ** Does MySQL Enterprise include Emergency Hot Fix Builds?  *

MySQL Enterprise, at the Gold and Platinum tiers, gives you the ability
to request an Emergency Hot Fix Build to fix issues not already fixed
in a MySQL Rapid Update or MySQL Quarterly Service Pack.

*15.12.9: ** Are there any MySQL Enterprise White Papers available?  *

Yes. Detailed architecture, technology, and business white papers are
available.  Learn More (/products/enterprise/whitepapers.html)

*15.12.10: ** How do I buy MySQL Enterprise?  *

For pricing and to buy MySQL Enterprise, visit the Online Shop
(https://shop.mysql.com/enterprise/) For volume discounts or for more
information, please Contact MySQL Sales
(/about/contact/sales.html?s=corporate)

*15.12.11: ** What is MySQL Enterprise?  *

The MySQL Enterprise subscription is the most comprehensive offering of
MySQL database software, services and production support to ensure your
business achieves the highest levels of reliability, security and
uptime.

MySQL Enterprise includes:

   * MySQL Enterprise Server software, the most reliable, secure and
     up-to date version of the world's most popular open source database

   * MySQL Enterprise Monitor that continuously monitors your database
     and proactively advises you on how to implement MySQL best
     practices

   * MySQL 24x7 Production Support with fast response times to assist
     you in the development, deployment and management of MySQL
     applications

MySQL Enterprise is available in 4 tiers (Basic, Silver, Gold,
Platinum). Learn More (/products/enterprise/features.html)

*15.12.12: ** Does MySQL provide IP (Intellectual Property)
Indemnification?  *

MySQL Enterprise, at the Gold and Platinum tiers, has the option of IP
Indemnification, for qualifying customers at no extra cost. This
provides you with legal protection that you expect from enterprise
software providers.  Learn More
(/products/enterprise/indemnification.html)

*15.12.13: ** Can I buy MySQL Enterprise subscriptions for multiple
years?  *

MySQL Enterprise subscriptions have duration of at least 1 year.
Customers have the flexibility of choosing terms with multi-year
durations. To purchase multi-year contracts, please Contact MySQL Sales
(/about/contact/sales.html?s=corporate)

*15.12.14: ** What is MySQL Enterprise Unlimited?  *

MySQL Enterprise Unlimited is a unique offering that allows you to
deploy an unlimited number of MySQL Enterprise Servers for the price of
a single CPU of Oracle Enterprise Edition.  Learn More
(/products/enterprise/unlimited.html)

*15.12.15: ** What is MySQL Production Support?  *

Production Support consists of 4 components:

   * Problem Resolution Support

   * Consultative Support

   * Knowledge Base

   * Technical Account Manager (option)

MySQL Production Support gives you priority access with guaranteed
response times to assist you with the development, deployment and
management of your MySQL applications.  Learn More
(/products/enterprise/support.html)

*15.12.16: ** Can I buy MySQL Enterprise subscriptions for only some of
my production MySQL database servers?  *

When you choose MySQL Enterprise subscriptions, they must cover all
database servers that power that specific application. To negotiate
volume discounts, please Contact MySQL Sales
(/about/contact/sales.html?s=corporate)

*15.12.17: ** Are there any Demo/Tutorials available for MySQL
Enterprise?  *

Yes. Multiple self-running demos are available.  Learn More
(/products/enterprise/demo.html)

*15.12.18: ** Does MySQL Enterprise include 24x7 Technical Support?  *

MySQL Enterprise, at the Gold and Platinum tiers, includes 24x7 phone
and email access to the MySQL Support Team.  Learn More
(/products/enterprise/problemresolution.html)

*15.12.19: ** What if I plan to add more MySQL servers to my MySQL
Enterprise subscription?  *

A great option is the MySQL Enterprise Unlimited offering that allows
you cover an unlimited number of MySQL servers for a fixed, low price.
Learn More (/products/enterprise/unlimited.html)

*15.12.20: ** What is the list of Supported Platforms?  *

MySQL Enterprise provides broad coverage in its list of Supported
Platforms.  Learn More (/support/supportedplatforms/)

*15.12.21: ** Do all my MySQL Enterprise subscriptions need to be at
the same tier?  *

MySQL Enterprise subscriptions must be at the same tier (Basic, Silver,
Gold, Platinum) for all database servers that power that specific
application.

*15.12.22: ** What is MySQL Consultative Support?  *

MySQL Enterprise, at the Gold and Platinum tiers, includes Consultative
Support. This is a proactive approach to support that is designed to
help you avoid critical outages. MySQL Support Engineers advise you on
how to properly design and tune your MySQL servers, schema, queries,
and replication set-up to maximize performance and availability. Also,
by taking the initiative to properly design and tune your MySQL database
applications you can avoid having to purchase expensive hardware for
your IT infrastructure.  Learn More
(/products/enterprise/consultativesupport.html)

*MySQL Monitor*

*Questions*
   * 15.12.1: What is MySQL Enterprise Monitor?

   * 15.12.2: What versions of MySQL are supported by the MySQL
     Enterprise Monitor?

   * 15.12.3: What MySQL Enterprise subscription levels include the
     MySQL Enterprise Monitor?

   * 15.12.4: What are the features and related benefits of the MySQL
     Enterprise Monitor?

   * 15.12.5: What are the MySQL Enterprise Advisors and Advisor Rules?

   * 15.12.6: How is the Enterprise Monitor web application architected?

   * 15.12.7: What operating system platforms are supported by the MySQL
     Enterprise Monitor?

   * 15.12.8: How do I get the MySQL Enterprise Monitor?

   * 15.12.9: What makes MySQL Enterprise unique?

   * 15.12.10: What are the long-term benefits of the MySQL Enterprise
     Monitor?

   * 15.12.11: Which set of Enterprise Advisors, Advisor Rules and
     features are best for my use of MySQL?

   * 15.12.12: How is the MySQL Enterprise Monitor installed and
     deployed?

   * 15.12.13: What are the immediate benefits of implementing the MySQL
     Enterprise Monitor?

   * 15.12.14: How are subscribers notified about the availability of
     new or updated MySQL Enterprise Monitor, MySQL Enterprise Advisors
     and Advisor Rules?

   * 15.12.15: Which Advisors and features are included under different
     MySQL Enterprise subscription levels?

*Questions and Answers* *15.12.1: ** What is MySQL Enterprise Monitor?
*

Included as part of a MySQL Enterprise subscription, the MySQL
Enterprise Monitor is a distributed, web-based application that helps
customers reduce downtime, tighten security and increase throughput of
their MySQL servers by telling them about problems in their database
applications before they occur. It is downloadable from the Enterprise
Customer web site and is deployed within the safety of the customer
datacenter.Learn More (/products/enterprise/monitor.html)

*15.12.2: ** What versions of MySQL are supported by the MySQL
Enterprise Monitor?  *

The MySQL Enterprise Monitor can be used to monitor MySQL versions 4.0
- 5.x.

*15.12.3: ** What MySQL Enterprise subscription levels include the MySQL
Enterprise Monitor?  *

The Enterprise Monitor is available under MySQL Enterprise subscription
levels Silver, Gold and Platinum.  Learn More
(/products/enterprise/features.html)

*15.12.4: ** What are the features and related benefits of the MySQL
Enterprise Monitor?  *

The MySQL Enterprise Monitor is like having a "Virtual DBA Assistant"
at your side to recommend best practices to eliminate security
vulnerabilities, improve replication, and optimize performance. For the
complete features and benefits, visit the MySQL Enterprise Monitor
Features and Benefits page (/products/enterprise/monitor-features.html).

*15.12.5: ** What are the MySQL Enterprise Advisors and Advisor Rules?
*

The MySQL Enterprise Advisors are a set of best practice guidelines for
the optimal use of MySQL. Advisors are spread across database specific
disciplines and are comprised of a set of MySQL Advisor Rules that
proactively monitor all MySQL servers and report on database
application problems before they occur. Each Advisor Rule provides a
detailed overview of the problem it is designed to identify, advices on
how to correct the problem, specifies commands to implement the
recommended fix and links to additional resources for additional
research into the issue at hand.  Learn More
(/products/enterprise/advisors.html)

*15.12.6: ** How is the Enterprise Monitor web application architected?
*

The Enterprise Monitor web application is comprised of 3 components:

   * Service Agent: A lightweight C program that is installed on each
     of the monitored MySQL servers. Its purpose is to collect MySQL
     SQL and operating system metrics that allow the DBA to monitor the
     overall health, availability and performance of the MySQL server.
     The Service Agent is the only component within the application
     that touches or connects to the MySQL Server. It reports the data
     it collects via XML over HTTP to the centralized Service Manager.

   * Service Manager: The main server of the application. The Service
     Manager manages and stores the data collections that come in from
     each service agent. It analyzes these collections using MySQL
     provided best practice Advisor rules to determine the health,
     security, availability and performance of each of the monitored
     MySQL Servers. The Service Manager also provides the content for
     the Enterprise Dashboard which serves as the client user interface
     for the distributed web application.

   * Repository: A MySQL database that is used to stored data
     collections and application-level configuration data.

*15.12.7: ** What operating system platforms are supported by the MySQL
Enterprise Monitor?  *

The Enterprise Monitor Service Manager is fully supported on most
current versions of Linux, Windows XP and Server Editions, Solaris and
Mac OSX. The Service Agent supports any platform supported by the MySQL
Enterprise server. For the complete list of MySQL Enterprise supported
operating systems and CPUs, visit the Supported Platforms page
(/support/supportedplatforms/enterprise.html).

*15.12.8: ** How do I get the MySQL Enterprise Monitor?  *

The MySQL Enterprise Monitor is available for download to MySQL
Enterprise customers at the Silver, Gold and Platinum subscription
levels.

   * To experience the MySQL Enterprise Monitor for 30 days, visit the
     Trial Subscription page (/trials/enterprise)

   * To buy MySQL Enterprise, visit the Online Shop
     (https://shop.mysql.com/enterprise/)

*15.12.9: ** What makes MySQL Enterprise unique?  *

Of the products on the market that monitor MySQL, SQL code and OS
specific metrics, the MySQL Enterprise Monitor is the only solution
that is built and supported by the engineers at MySQL.  Unlike other
solutions that report on raw MySQL and OS level metrics, the MySQL
Enterprise Monitor is designed to optimize the use of MySQL by
proactively monitoring MySQL instances and providing notifications and
"MySQL DBA expertise in a box" advice on corrective measures DBAs can
take before problems occur.

*15.12.10: ** What are the long-term benefits of the MySQL Enterprise
Monitor?  *

Over time, the task of managing even medium-scale MySQL server farms
becomes exponentially more complicated, especially as the load of
users, connections, application queries, and objects on each MySQL
server increases. The Enterprise Monitor continually monitors the
dynamic security, performance, replication and schema relevant metrics
of all MySQL servers, so as the number of MySQL continues to grow, DBAs
are kept up to date on potential problems and proactive measures that
can be implemented to ensure each server continues to operate at the
highest levels of security, performance and reliability.

*15.12.11: ** Which set of Enterprise Advisors, Advisor Rules and
features are best for my use of MySQL?  *

The Enterprise Monitor Advisors and Advisor Rules are available at 3
MySQL Enterprise subscription tiers: Choose MySQL Enterprise Silver if
you need:

   * Assurance you are running the most current, bug-free version of
     MySQL across all of your servers.

   * Recoverability of your MySQL servers.

   * The highest level of security for your MySQL servers.

   * Monitoring of maximum or disallowed MySQL connections.

   * Optimized startup configuration settings.

Choose MySQL Enterprise Gold, when you need everything in Silver, PLUS:

   * Easy collection and detection of problematic SQL code running on
     your production or development systems.

   * Insight and corrective advice on MySQL replication status, sync,
     and performance related issues.

   * Auto detection and documenting of your Replication topologies.

   * Advanced monitoring of your Replication and Scale-out environment.

Choose MySQL Enterprise Platinum, when you need everything in Gold,
PLUS:

   * Identification and advice on unplanned database and object level
     schema changes (Create, Alter, and Drop) across your MySQL servers.

   * Proactive monitoring and advice on tuning the performance of your
     MySQL servers.

*15.12.12: ** How is the MySQL Enterprise Monitor installed and
deployed?  *

The Enterprise Monitor is powered by a distributed web application that
is installed and deployed within the confines of the corporate firewall.

*15.12.13: ** What are the immediate benefits of implementing the MySQL
Enterprise Monitor?  *

Often MySQL installations are implemented with default settings that
may not be best suited for specific applications or usage patterns. The
MySQL Advisors go to work immediately in these environments to identify
potential problems and proactively notify and advise DBAs on key MySQL
settings that can be tuned to improve availability, tighten security,
and increase the throughput of their existing MySQL servers

*15.12.14: ** How are subscribers notified about the availability of
new or updated MySQL Enterprise Monitor, MySQL Enterprise Advisors and
Advisor Rules?  *

Customers will receive notifications of new and updated MySQL
Enterprise Monitor and Advisors as they become available via the MySQL
Enterprise Software Update Service. Notifications will be generated and
sent based on the customer profile and the MySQL Enterprise
subscription level.

*15.12.15: ** Which Advisors and features are included under different
MySQL Enterprise subscription levels?  *

For the complete list of the MySQL Enterprise Advisors that are
available under each MySQL Enterprise subscription level, visit the
Features page (/products/enterprise/features.html).

*MySQL Query Analyzer*

*Questions*
   * 15.12.1: Can I leave the MySQL Query Analyzer enabled at all times?

   * 15.12.2: What are the typical use cases of the MySQL Query
     Analyzer?

   * 15.12.3: What is the MySQL Query Analyzer?

   * 15.12.4: What are the main features and benefits of the MySQL Query
     Analyzer?

   * 15.12.5: What makes the MySQL Query Analyzer unique?

   * 15.12.6: How are subscribers notified about updates to the MySQL
     Query Analyzer application components?

   * 15.12.7: How can I get the MySQL Query Analyzer?

   * 15.12.8: How is the MySQL Query Analyzer installed and enabled?

   * 15.12.9: What overhead can I expect when the MySQL Query Analyzer
     is installed and enabled?

*Questions and Answers* *15.12.1: ** Can I leave the MySQL Query
Analyzer enabled at all times?  *

We have customers who have the Query Analyzer enabled and collecting
queries on their development and QA servers so they can tune their code
and monitor the fixes as part of the development process. For
production systems, Query collection and analysis can easily be toggled
on when a slowdown occurs. To avoid collection mode overhead many users
are using simple scripts to enable the Query Analyzer to sample queries
during non-peak hours, typically during 30 minute windows. They can
then view the collected queries using the date/time or interval filter
options.

*15.12.2: ** What are the typical use cases of the MySQL Query Analyzer?
*

The typical use cases for developers, DBAs and system administrators
are:

   * Developers - Monitor and tune application queries during
     development before they are promoted to production.

   * DBAs and System Administrators - Identify problem SQL code as it
     runs in production and advise development teams on how to tune.
     This use case benefits the most from regular sampling of queries
     as they are running, most often during non-peak hours.

*15.12.3: ** What is the MySQL Query Analyzer?  *

The MySQL Query Analyzer allows DBAs, developers and system
administrators to improve application performance by collecting,
monitoring, and analyzing queries as they run on their MySQL servers.
Learn More (/products/enterprise/query.html)

*15.12.4: ** What are the main features and benefits of the MySQL Query
Analyzer?  *

For the complete features and benefits, visit the MySQL Enterprise
Monitor Features and Benefits page.
(/products/enterprise/monitor-features.html)

*15.12.5: ** What makes the MySQL Query Analyzer unique?  *

Other products (free, open source and commercial) that provide MySQL
query monitoring are dependent on the MySQL Slow Query Log being
enabled and available for sampling. While this provides some time
savings over the DBA collecting and parsing the Log, the Slow Query Log
comes with overhead and does not capture sub millisecond executions.
The log data also grows very large very quickly.

The MySQL Query Analyzer collects queries and execution statistics with
no dependence on the SQL Query Log, it captures all SQL statements sent
to the MySQL server and provides an aggregated view into the most
expensive queries in number of executions and total execution time. It
is also fully supported as part of the MySQL Enterprise subscription.

*15.12.6: ** How are subscribers notified about updates to the MySQL
Query Analyzer application components?  *

Customers will receive notifications of the MySQL Query Analyzer
updates as they become available via the MySQL Enterprise Software
Update and Alert Service. Notifications will be generated and sent
based on the customer profile and the MySQL Enterprise subscription
level.

*15.12.7: ** How can I get the MySQL Query Analyzer?  *

The MySQL Query Analyzer is available for download to MySQL Enterprise
customers at the Gold and Platinum subscription levels.

   * To experience the MySQL Enterprise Monitor for 30 days, visit the
     Trial Subscription page (/trials/enterprise)

   * To buy MySQL Enterprise, visit the Online Shop
     (https://shop.mysql.com/enterprise/)

*15.12.8: ** How is the MySQL Query Analyzer installed and enabled?  *

The Query Analyzer feature is installed with the Service Agent.  It is
enabled during agent installation and can be toggled between collection
and pass-thru modes from the Query Analysis page of the Enterprise
Monitor.

*15.12.9: ** What overhead can I expect when the MySQL Query Analyzer is
installed and enabled?  *

The average overhead when in active collection mode is in the 15-20%
range. In pass-thru mode the overhead is minimal, weighing in at 1-5%
on most MySQL systems of average load.


File: manual.info,  Node: replication,  Next: partitioning,  Prev: mem-introduction,  Up: Top

16 Replication
**************

* Menu:

* replication-configuration::    Replication Configuration
* replication-solutions::        Replication Solutions
* replication-notes::            Replication Notes and Tips
* replication-implementation::   Replication Implementation

Replication enables data from one MySQL database server (called the
master) to be replicated to one or more MySQL database servers
(slaves). Replication is asynchronous by default - your replication
slaves do not need to be connected permanently to receive updates from
the master, which means that updates can occur over long-distance
connections and even temporary solutions such as a dial-up service.
Depending on the configuration, you can replicate all databases,
selected databases, or even selected tables within a database.

The target uses for replication in MySQL include:

   * Scale-out solutions - spreading the load among multiple slaves to
     improve performance. In this environment, all writes and updates
     must take place on the master server. Reads, however, may take
     place on one or more slaves. This model can improve the
     performance of writes (since the master is dedicated to updates),
     while dramatically increasing read speed across an increasing
     number of slaves.

   * Data security - because data is replicated to the slave, and the
     slave can pause the replication process, it is possible to run
     backup services on the slave without corrupting the corresponding
     master data.

   * Analytics - live data can be created on the master, while the
     analysis of the information can take place on the slave without
     affecting the performance of the master.

   * Long-distance data distribution - if a branch office would like to
     work with a copy of your main data, you can use replication to
     create a local copy of the data for their use without requiring
     permanent access to the master.

Replication in MySQL features support for one-way, asynchronous
replication, in which one server acts as the master, while one or more
other servers act as slaves. This is in contrast to the _synchronous_
replication which is a characteristic of MySQL Cluster (see MySQL
Cluster NDB 6.X/7.X
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html)). As of
version 6.0.8, MySQL supports an interface to semisynchronous
replication in addition to the built-in asynchronous replication. With
semisynchronous replication, a commit performed on the master side
blocks before returning to the session that performed the transaction
until at least one slave acknowleges that it has received and logged
the events for the transaction.

There are a number of solutions available for setting up replication
between two servers, but the best method to use depends on the presence
of data and the engine types you are using. For more information on the
available options, see *Note replication-howto::.

There are two core types of replication format, Statement Based
Replication (SBR), which replicates entire SQL statements, and Row
Based Replication (RBR), which replicates only the changed rows. You
may also use a third variety, Mixed Based Replication (MBR), which is
the default mode. For more information on the different replication
formats, see *Note replication-formats::.

Replication is controlled through a number of different options and
variables. These control the core operation of the replication,
timeouts and the databases and filters that can be applied on databases
and tables. For more information on the available options, see *Note
replication-options::.

You can use replication to solve a number of different problems,
including problems with performance, supporting the backup of different
databases and for use as part of a larger solution to alleviate system
failures. For information on how to address these issues, see *Note
replication-solutions::.

For notes and tips on how different data types and statements are
treated during replication, including details of replication features,
version compatibility, upgrades, and problems and their resolution,
including an FAQ, see *Note replication-notes::.

Detailed information on the implementation of replication, how
replication works, the process and contents of the binary log,
background threads and the rules used to decide how statements are
recorded and replication, see *Note replication-implementation::.

MySQL Enterprise

The MySQL Enterprise Monitor provides numerous advisors that provide
immediate feedback about replication-related problems. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: replication-configuration,  Next: replication-solutions,  Prev: replication,  Up: replication

16.1 Replication Configuration
==============================

* Menu:

* replication-howto::            How to Set Up Replication
* replication-formats::          Replication Formats
* replication-options::          Replication and Binary Logging Options and Variables
* replication-administration::   Common Replication Administration Tasks

Replication between servers in MySQL works through the use of the
binary logging mechanism. The MySQL instance operating as the master
(the source of the database changes) writes updates and changes as
`events' to the binary log. The information in the binary log is stored
in different logging formats according to the database changes being
recorded. Slaves are configured to read the binary log from the master
and to execute the events in the binary log on the slave's local
database.

The master is `dumb' in this scenario. Once binary logging has been
enabled, all statements are recorded in the binary log. Each slave will
receive a copy of the entire contents of the binary log. It is the
responsibility of the slave to decide which statements in the binary
log should be executed; you cannot configure the master to log only
certain events. If you do not specify otherwise, all events in the
master binary log are executed on the slave. If required, you can
configure the slave to process only events that apply to particular
databases or tables.

Each slave keeps a record of the binary log file and position within
the log file that it has read and processed from the master. This means
that multiple slaves can be connected to the master and executing
different parts of the same binary log. Because the slaves control this
process, individual slaves can be connected and disconnected from the
server without affecting the master's operation. Also, because each
slave remembers the position within the binary log, it is possible for
slaves to be disconnected, reconnect and then `catch up' by continuing
from the recorded position.

Both the master and each slave must be configured with a unique ID
(using the `server-id' option). In addition, the slave must be
configured with information about the master host name, log file name
and position within that file. These details can be controlled from
within a MySQL session using the *Note `CHANGE MASTER TO':
change-master-to. statement. The details are stored within the
`master.info' file.

In this section the setup and configuration required for a replication
environment is described, including step-by-step instructions for
creating a new replication environment. The major components of this
section are:

   * For a guide to setting up two or more servers for replication see
     *Note replication-howto::. This section deals with the setup of
     the systems and provides methods for copying data between the
     master and slaves.

   * Events in the binary log are recorded using a number of formats.
     These are referred to as statement-based replication (SBR) or
     row-based replication (RBR). A third type, mixed-format
     replication (MIXED), uses SBR or RBR replication automatically to
     take advantage of the benefits of both SBR and RBR formats when
     appropriate. The different formats are discussed in *Note
     replication-formats::.

   * Detailed information on the different configuration options and
     variables that apply to replication is provided in *Note
     replication-options::.

   * Once started, the replication process should require little
     administration or monitoring. However, for advice on common tasks
     that you may want to execute, see *Note
     replication-administration::.


File: manual.info,  Node: replication-howto,  Next: replication-formats,  Prev: replication-configuration,  Up: replication-configuration

16.1.1 How to Set Up Replication
--------------------------------

* Menu:

* replication-howto-repuser::    Creating a User for Replication
* replication-howto-masterbaseconfig::  Setting the Replication Master Configuration
* replication-howto-slavebaseconfig::  Setting the Replication Slave Configuration
* replication-howto-masterstatus::  Obtaining the Master Replication Information
* replication-howto-mysqldump::  Creating a Data Snapshot Using `mysqldump'
* replication-howto-rawdata::    Creating a Data Snapshot Using Raw Data Files
* replication-howto-newservers::  Setting Up Replication with New Master and Slaves
* replication-howto-existingdata::  Setting Up Replication with Existing Data
* replication-howto-additionalslaves::  Introducing Additional Slaves to an Existing Replication Environment
* replication-howto-slaveinit::  Setting the Master Configuration on the Slave

This section describes how to set up complete replication of a MySQL
server. There are a number of different methods for setting up
replication, and the exact method that you use will depend on how you
are setting up replication, and whether you already have data within
your master database.

There are some generic tasks which may be required for all replication
setups:

   * You may want to create a separate user that will be used by your
     slaves to authenticate with the master to read the binary log for
     replication. The step is optional. See *Note
     replication-howto-repuser::.

   * You must configure the master to support the binary log and
     configure a unique ID. See *Note
     replication-howto-masterbaseconfig::.

   * You must configure a unique ID for each slave that you want to
     connect to the master. See *Note
     replication-howto-slavebaseconfig::.

   * Before starting a data snapshot or the replication process, you
     should record the position of the binary log on the master. You
     will need this information when configuring the slave so that the
     slave knows where within the binary log to start executing events.
     See *Note replication-howto-masterstatus::.

   * If you already have data on your master and you want to
     synchronize your slave with this base data, then you will need to
     create a data snapshot of your database. You can create a snapshot
     using *Note `mysqldump': mysqldump. (see *Note
     replication-howto-mysqldump::) or by copying the data files
     directly (see *Note replication-howto-rawdata::).

   * You will need to configure the slave with the master settings,
     such as the host name, login credentials and binary log name and
     positions. See *Note replication-howto-slaveinit::.

Once you have configured the basic options, you will need to follow the
instructions for your replication setup. A number of alternatives are
provided:

   * If you are establishing a new MySQL master and one or more slaves,
     then you need only set up the configuration, as you have no data
     to exchange. For guidance on setting up replication in this
     situation, see *Note replication-howto-newservers::.

   * If you are already running a MySQL server, and therefore already
     have data that will need to be transferred to your slaves before
     replication starts, have not previously configured the binary log
     and are able to shut down your MySQL server for a short period
     during the process, see *Note replication-howto-existingdata::.

   * If you are setting up additional slaves to an existing replication
     environment then you can set up the slaves without affecting the
     master. See *Note replication-howto-additionalslaves::.

If you want to administer a MySQL replication setup, we suggest that
you read this entire chapter through and try all statements mentioned
in *Note replication-master-sql::, and *Note replication-slave-sql::.
You should also familiarize yourself with the replication startup
options described in *Note replication-options::.

*Note*:

Note that certain steps within the setup process require the `SUPER'
privilege. If you do not have this privilege then enabling replication
may not be possible.


File: manual.info,  Node: replication-howto-repuser,  Next: replication-howto-masterbaseconfig,  Prev: replication-howto,  Up: replication-howto

16.1.1.1 Creating a User for Replication
........................................

Each slave must connect to the master using a standard MySQL user name
and password, so there must be a user account on the master that the
slave can use to connect. Any account can be used for this operation,
providing it has been granted the `REPLICATION SLAVE' privilege.

You do not need to create a specific user for replication.  However,
you should be aware that the user name and password will be stored in
plain text within the `master.info' file. Therefore, you may want to
create a user that only has privileges for the replication process.

To create a user or grant an existing user the privileges required for
replication, use the *Note `GRANT': grant. statement. If you create a
user solely for the purposes of replication then that user needs only
the `REPLICATION SLAVE' privilege. For example, to create a user,
`repl', that can connect for replication from any host within the
`mydomain.com' domain, issue this statement on the master:

     mysql> GRANT REPLICATION SLAVE ON *.*
         -> TO 'repl'@'%.mydomain.com' IDENTIFIED BY 'slavepass';

See *Note grant::, for more information on the *Note `GRANT': grant.
statement.

You may wish to create a different user for each slave, or use the same
user for each slave that needs to connect. As long as each user that
you want to use for the replication process has the `REPLICATION SLAVE'
privilege you can create as many users as you require.


File: manual.info,  Node: replication-howto-masterbaseconfig,  Next: replication-howto-slavebaseconfig,  Prev: replication-howto-repuser,  Up: replication-howto

16.1.1.2 Setting the Replication Master Configuration
.....................................................

For replication to work you _must_ enable binary logging on the master.
If binary logging is not enabled, replication will not be possible as
it is the binary log that is used to exchange data between the master
and slaves.

Each server within a replication group must be configured with a unique
`server-id' value. The server ID is used to identify individual servers
within the group, and must be positive integer between 1 and (2^32)-1.
How you organize and select the numbers is entirely up to you.

To configure the binary log and server ID options, you will need to
shut down your MySQL server and edit the configuration of the `my.cnf'
or `my.ini' file.

You will need to add the following options to the configuration file
within the `[mysqld]' section. If these options already exist, but are
commented out, uncomment the options and alter them according to your
needs. For example, to enable binary logging, using a log file name
prefix of `mysql-bin', and setting a server ID of 1:

     [mysqld]
     log-bin=mysql-bin
     server-id=1

*Note*:

For the greatest possible durability and consistency in a replication
setup using `InnoDB' with transactions, you should use
`innodb_flush_log_at_trx_commit=1' and `sync_binlog=1' in the master
`my.cnf' file.

*Note*:

Ensure that the `skip-networking' option has not been enabled on your
replication master. If networking has been disabled, then your slave
will not able to communicate with the master and replication will fail.


File: manual.info,  Node: replication-howto-slavebaseconfig,  Next: replication-howto-masterstatus,  Prev: replication-howto-masterbaseconfig,  Up: replication-howto

16.1.1.3 Setting the Replication Slave Configuration
....................................................

The only option you must configure on the slave is to set the unique
server ID. If this option is not already set, or the current value
conflicts with the value that you have chosen for the master server,
then you should shut down your slave server, and edit the configuration
to specify the server ID. For example:

     [mysqld]
     server-id=2

If you are setting up multiple slaves, each one must have a unique
`server-id' value that differs from that of the master and from each of
the other slaves. Think of `server-id' values as something similar to
IP addresses: These IDs uniquely identify each server instance in the
community of replication partners.

If you do not specify a `server-id' value, it defaults to 0.

*Note*:

If you omit `server-id' (or set it explicitly to 0), a master refuses
connections from all slaves, and a slave refuses to connect to a
master. Thus, omitting `server-id' is good only for backup with a
binary log.

You do not have to enable binary logging on the slave for replication
to be enabled. However, if you enable binary logging on the slave then
you can use the binary log for data backups and crash recovery on the
slave, and also use the slave as part of a more complex replication
topology (for example, where the slave acts as a master to other
slaves).


File: manual.info,  Node: replication-howto-masterstatus,  Next: replication-howto-mysqldump,  Prev: replication-howto-slavebaseconfig,  Up: replication-howto

16.1.1.4 Obtaining the Master Replication Information
.....................................................

To configure replication on the slave you must determine the master's
current point within the master binary log. You will need this
information so that when the slave starts the replication process, it
is able to start processing events from the binary log at the correct
point.

If you have existing data on your master that you want to synchronize
on your slaves before starting the replication process, then you must
stop processing statements on the master, obtain the current position,
and then dump the data, before allowing the master to continue
executing statements. If you do not stop the execution of statements,
the data dump and the master status information that you use will not
match and you will end up with inconsistent or corrupted databases on
the slaves.

To get the master status information, follow these steps:

  1. Start the command-line client and flush all tables and block write
     statements by executing the *Note `FLUSH TABLES WITH READ LOCK':
     flush. statement:

          mysql> FLUSH TABLES WITH READ LOCK;

     For `InnoDB' tables, note that *Note `FLUSH TABLES WITH READ
     LOCK': flush. also blocks *Note `COMMIT': commit. operations.

     *Warning*:

     Leave the client from which you issued the *Note `FLUSH TABLES':
     flush. statement running so that the read lock remains in effect.
     If you exit the client, the lock is released.

  2. Use the *Note `SHOW MASTER STATUS': show-master-status.  statement
     to determine the current binary log file name and offset on the
     master:

          mysql > SHOW MASTER STATUS;
          +---------------+----------+--------------+------------------+
          | File          | Position | Binlog_Do_DB | Binlog_Ignore_DB |
          +---------------+----------+--------------+------------------+
          | mysql-bin.003 | 73       | test         | manual,mysql     |
          +---------------+----------+--------------+------------------+

     The `File' column shows the name of the log file and `Position'
     shows the offset within the file. In this example, the binary log
     file is `mysql-bin.003' and the offset is 73.  Record these
     values. You need them later when you are setting up the slave.
     They represent the replication coordinates at which the slave
     should begin processing new updates from the master.

     If the master has been running previously without binary logging
     enabled, the log name and position values displayed by *Note `SHOW
     MASTER STATUS': show-master-status. or *Note `mysqldump
     --master-data': mysqldump. will be empty. In that case, the values
     that you need to use later when specifying the slave's log file
     and position are the empty string (`''') and `4'.

You now have the information you need to enable the slave to start
reading from the binary log in the correct place to start replication.

If you have existing data that needs be to synchronized with the slave
before you start replication, leave the client running so that the lock
remains in place and then proceed to *Note
replication-howto-mysqldump::, or *Note replication-howto-rawdata::.

If you are setting up a brand new master and slave replication group,
then you can exit the client and release the locks.


File: manual.info,  Node: replication-howto-mysqldump,  Next: replication-howto-rawdata,  Prev: replication-howto-masterstatus,  Up: replication-howto

16.1.1.5 Creating a Data Snapshot Using `mysqldump'
...................................................

One way to create a snapshot of the data in an existing master database
is to use the *Note `mysqldump': mysqldump. tool. Once the data dump
has been completed, you then import this data into the slave before
starting the replication process.

To obtain a snapshot of the data using *Note `mysqldump': mysqldump.:

   * If you haven't already locked the tables on the server to prevent
     statements that update data from executing:

     Start the command-line client and flush all tables and block write
     statements by executing the *Note `FLUSH TABLES WITH READ LOCK':
     flush. statement:

          mysql> FLUSH TABLES WITH READ LOCK;

     Remember to use *Note `SHOW MASTER STATUS': show-master-status.
     and record the binary log details for use when starting up the
     slave. The point in time of your snapshot and the binary log
     position must match. See *Note replication-howto-masterstatus::.

   * In another session, use *Note `mysqldump': mysqldump. to create a
     dump either of all the databases you want to replicate, or of
     selected individual databases. For example:

          shell> mysqldump --all-databases --lock-all-tables >dbdump.db

   * An alternative to using a bare dump, is to use the `--master-data'
     option, which automatically appends the *Note `CHANGE MASTER TO':
     change-master-to.  statement required on the slave to start the
     replication process.

          shell> mysqldump --all-databases --master-data >dbdump.db

   * In the client where you acquired the read lock, release the lock:

          mysql> UNLOCK TABLES;

When choosing databases to include in the dump, remember that you will
need to filter out databases on each slave that you do not want to
include in the replication process.

You will need either to copy the dump file to the slave, or to use the
file from the master when connecting remotely to the slave to import
the data.


File: manual.info,  Node: replication-howto-rawdata,  Next: replication-howto-newservers,  Prev: replication-howto-mysqldump,  Up: replication-howto

16.1.1.6 Creating a Data Snapshot Using Raw Data Files
......................................................

If your database is particularly large, copying the raw data files may
be more efficient than using *Note `mysqldump': mysqldump. and
importing the file on each slave.

However, using this method with tables in storage engines with complex
caching or logging algorithms may not give you a perfect `in time'
snapshot as cache information and logging updates may not have been
applied, even if you have acquired a global read lock. How the storage
engine responds to this depends on its crash recovery abilities.

In addition, this method does not work reliably if the master and slave
have different values for `ft_stopword_file', `ft_min_word_len', or
`ft_max_word_len' and you are copying tables having fulltext indexes.

If you are using `InnoDB' tables, you should use the ``InnoDB' Hot
Backup' tool to obtain a consistent snapshot. This tool records the log
name and offset corresponding to the snapshot to be later used on the
slave. `Hot Backup' is a non-free (commercial) tool that is not
included in the standard MySQL distribution. See the ``InnoDB' Hot
Backup' home page at `http://www.innodb.com/hot-backup' for detailed
information.

Otherwise, you can obtain a reliable binary snapshot of `InnoDB' tables
only after shutting down the MySQL Server.

To create a raw data snapshot of `MyISAM' tables you can use standard
copy tools such as `cp' or `copy', a remote copy tool such as `scp' or
`rsync', an archiving tool such as `zip' or `tar', or a file system
snapshot tool such as `dump', providing that your MySQL data files
exist on a single file system. If you are replicating only certain
databases then make sure you copy only those files that related to
those tables. (For `InnoDB', all tables in all databases are stored in
a single file unless you have the `innodb_file_per_table' option
enabled.)

You may want to specifically exclude the following files from your
archive:

   * Files relating to the `mysql' database.

   * The `master.info' file.

   * The master's binary log files.

   * Any relay log files.

To get the most consistent results with a raw data snapshot you should
shut down the server during the process, as below:

  1. Acquire a read lock and get the master's status. See *Note
     replication-howto-masterstatus::.

  2. In a separate session, shut down the MySQL server:

          shell> mysqladmin shutdown

  3. Make a copy of the MySQL data files. Examples are shown below for
     common ways to do this - you need to choose only one of them:

          shell> tar cf /TMP/DB.TAR ./DATA
          shell> zip -r /TMP/DB.ZIP ./DATA
          shell> rsync --recursive ./DATA /TMP/DBDATA

  4. Start up the MySQL instance on the master.

If you are not using `InnoDB' tables, you can get a snapshot of the
system from a master without shutting down the server as described in
the following steps:

  1. Acquire a read lock and get the master's status. See *Note
     replication-howto-masterstatus::.

  2. Take a copy of the MySQL data files. Examples are shown below for
     common solutions - you need to choose only one of these solutions:

          shell> tar cf /TMP/DB.TAR ./DATA
          shell> zip -r /TMP/DB.ZIP ./DATA
          shell> rsync --recursive ./DATA /TMP/DBDATA

  3. In the client where you acquired the read lock, release the lock:

          mysql> UNLOCK TABLES;

Once you have created the archive or copy of the database, you will
need to copy the files to each slave before starting the slave
replication process.


File: manual.info,  Node: replication-howto-newservers,  Next: replication-howto-existingdata,  Prev: replication-howto-rawdata,  Up: replication-howto

16.1.1.7 Setting Up Replication with New Master and Slaves
..........................................................

Setting up replication with a new master and slaves (that is, with no
existing data) is the easiest and most straightforward method for
setting up replication.

You can also use this method if you are setting up new servers but have
an existing dump of the databases from a different server that you want
to load into your replication configuration. By loading the data into a
new master, the data will be automatically replicated to the slaves.

To set up replication between a new master and slave:

  1. Configure the MySQL master with the necessary configuration
     properties. See *Note replication-howto-masterbaseconfig::.

  2. Start up the MySQL master.

  3. Set up a user. See *Note replication-howto-repuser::.

  4. Obtain the master status information. See *Note
     replication-howto-masterstatus::.

  5. On the master, release the read lock:

          mysql> UNLOCK TABLES;

  6. On the slave, edit the MySQL configuration. See *Note
     replication-howto-slavebaseconfig::.

  7. Start up the MySQL slave.

  8. Execute the *Note `CHANGE MASTER TO': change-master-to.  statement
     to set the master replication server configuration.

Perform the slave setup steps on each slave.

Because there is no data to load or exchange on a new server
configuration you do not need to copy or import any information.

If you are setting up a new replication environment using the data from
a different existing database server, you will now need to run the dump
file generated from that server on the new master. The database updates
will automatically be propagated to the slaves:

     shell> mysql -h master < fulldb.dump


File: manual.info,  Node: replication-howto-existingdata,  Next: replication-howto-additionalslaves,  Prev: replication-howto-newservers,  Up: replication-howto

16.1.1.8 Setting Up Replication with Existing Data
..................................................

When setting up replication with existing data, you will need to decide
how best to get the data from the master to the slave before starting
the replication service.

The basic process for setting up replication with existing data is as
follows:

  1. If you have not already configured the `server-id' and binary
     logging, you will need to shut down your master to configure these
     options. See *Note replication-howto-masterbaseconfig::.

     If you have to shut down your master server, this is a good
     opportunity to take a snapshot of its databases. You should obtain
     the master status (see *Note replication-howto-masterstatus::)
     before taking down the master, updating the configuration and
     taking a snapshot. For information on how to create a snapshot
     using raw data files, see *Note replication-howto-rawdata::.

  2. If your server is already correctly configured, obtain the master
     status (see *Note replication-howto-masterstatus::) and then use
     *Note `mysqldump': mysqldump. to take a snapshot (see *Note
     replication-howto-mysqldump::) or take a raw snapshot of the live
     server using the guide in *Note replication-howto-rawdata::.

  3. With the MySQL master running, create a user to be used by the
     slave when connecting to the master during replication.  See *Note
     replication-howto-repuser::.

  4. Update the configuration of the slave. See *Note
     replication-howto-slavebaseconfig::.

  5. The next step depends on how you created the snapshot of data on
     the master.

     If you used *Note `mysqldump': mysqldump.:

       1. Start the slave, skipping replication by using the
          `--skip-slave' option.

       2. Import the dump file:

               shell> mysql < fulldb.dump

     If you created a snapshot using the raw data files:

       1. Extract the data files into your slave data directory.  For
          example:

               shell> tar xvf dbdump.tar

          You may need to set permissions and ownership on the files to
          match the configuration of your slave.

       2. Start the slave, skipping replication by using the
          `--skip-slave' option.

  6. Configure the slave with the master status information. This will
     tell the slave the binary log file and position within the file
     where replication needs to start, and configure the login
     credentials and host name of the master. For more information on
     the statement required, see *Note replication-howto-slaveinit::.

  7. Start the slave threads:

          mysql> START SLAVE;

After you have performed this procedure, the slave should connect to
the master and catch up on any updates that have occurred since the
snapshot was taken.

If you have forgotten to set the `server-id' option for the master,
slaves cannot connect to it.

If you have forgotten to set the `server-id' option for the slave, you
get the following error in the slave's error log:

     Warning: You should set server-id to a non-0 value if master_host
     is set; we will force server id to 2, but this MySQL server will
     not act as a slave.

You also find error messages in the slave's error log if it is not able
to replicate for any other reason.

Once a slave is replicating, you can find in its data directory one
file named `master.info' and another named `relay-log.info'. The slave
uses these two files to keep track of how much of the master's binary
log it has processed. Do _not_ remove or edit these files unless you
know exactly what you are doing and fully understand the implications.
Even in that case, it is preferred that you use the *Note `CHANGE
MASTER TO': change-master-to.  statement to change replication
parameters. The slave will use the values specified in the statement to
update the status files automatically.

*Note*:

The content of `master.info' overrides some of the server options
specified on the command line or in `my.cnf'. See *Note
replication-options::, for more details.

Once you have a snapshot of the master, you can use it to set up other
slaves by following the slave portion of the procedure just described.
You do not need to take another snapshot of the master; you can use the
same one for each slave.


File: manual.info,  Node: replication-howto-additionalslaves,  Next: replication-howto-slaveinit,  Prev: replication-howto-existingdata,  Up: replication-howto

16.1.1.9 Introducing Additional Slaves to an Existing Replication Environment
.............................................................................

If you want to add another slave to the existing replication
configuration then you can do so without stopping the master.  Instead,
you duplicate the settings on the slaves by making a copy of one of the
slaves.

To duplicate the slave:

  1. Shut down the existing slave:

          shell> mysqladmin shutdown

  2. Copy the data directory from the existing slave to the new slave.
     You can do this by creating an archive using `tar' or `WinZip', or
     by performing a direct copy using a tool such as `cp' or `rsync'.
     Ensure that you also copy the log files and relay log files.

     *Note*:

     A common problem that is encountered when adding new replication
     slaves is that the new slave fails with a series of warning and
     error messages like these:

          071118 16:44:10 [Warning] Neither --relay-log nor --relay-log-index were used; so
          replication may break when this MySQL server acts as a slave and has his hostname
          changed!! Please use '--relay-log=NEW_SLAVE_HOSTNAME-relay-bin' to avoid this problem.
          `071118 16:44:10 [ERROR] Failed to open the relay log './OLD_SLAVE_HOSTNAME-relay-bin.003525'
          (relay_log_pos 22940879)'
          071118 16:44:10 `[ERROR] Could not find target log during relay log initialization'
          071118 16:44:10 `[ERROR] Failed to initialize the master info structure'

     This is due to the fact that, if the `--relay-log' option is not
     specified, the relay log files contain the host name as part of
     their file names. (This is also true of the relay log index file
     if the `--relay-log-index' option is not used. See *Note
     replication-options::, for more information about these options.)

     To avoid this problem, use the same value for `--relay-log' on the
     new slave that was used on the existing slave. (If this option was
     not set explicitly on the existing slave, use
     `EXISTING_SLAVE_HOSTNAME-relay-bin'.)  If this is not feasible,
     then copy the existing slave's relay log index file to the new
     slave and set the `--relay-log-index' option on the new slave to
     match what was used on the existing slave. (If this option was not
     set explicitly on the existing slave, use
     `EXISTING_SLAVE_HOSTNAME-relay-bin.index'.)  Alternatively -- if
     you have already tried to start the new slave (after following the
     remaining steps in this section) and have encountered errors like
     those described previously -- then perform the following steps:

       1. If you have not already done so, issue a *Note `STOP SLAVE':
          stop-slave. on the new slave.

          If you have already started the existing slave again, issue a
          *Note `STOP SLAVE': stop-slave. on the existing slave as well.

       2. Copy the contents of the existing slave's relay log index
          file into the new slave's relay log index file, making sure
          to overwrite any content already in the file.

       3. Proceed with the remaining steps in this section.

  3. Copy the `master.info' and `relay-log.info' files from the existing
     slave to the new slave. These files hold the current log positions.

  4. Start the existing slave.

  5. On the new slave, edit the configuration and the give the new
     slave a new unique `server-id'.

  6. Start the new slave; the `master.info' file options will be used
     to start the replication process.


File: manual.info,  Node: replication-howto-slaveinit,  Prev: replication-howto-additionalslaves,  Up: replication-howto

16.1.1.10 Setting the Master Configuration on the Slave
.......................................................

To set up the slave to communicate with the master for replication, you
must tell the slave the necessary connection information. To do this,
execute the following statement on the slave, replacing the option
values with the actual values relevant to your system:

     mysql> CHANGE MASTER TO
         ->     MASTER_HOST='MASTER_HOST_NAME',
         ->     MASTER_USER='REPLICATION_USER_NAME',
         ->     MASTER_PASSWORD='REPLICATION_PASSWORD',
         ->     MASTER_LOG_FILE='RECORDED_LOG_FILE_NAME',
         ->     MASTER_LOG_POS=RECORDED_LOG_POSITION;

*Note*:

Replication cannot use Unix socket files. You must be able to connect
to the master MySQL server using TCP/IP.

The following table shows the maximum allowable length for the
string-valued options.

*Option*       *Maximum
               Length*
`MASTER_HOST'  60
`MASTER_USER'  16
`MASTER_PASSWORD'32
`MASTER_LOG_FILE'255


File: manual.info,  Node: replication-formats,  Next: replication-options,  Prev: replication-howto,  Up: replication-configuration

16.1.2 Replication Formats
--------------------------

* Menu:

* replication-sbr-rbr::          Comparison of Statement-Based and Row-Based Replication
* replication-rbr-usage::        Usage of Row-based Logging and Row-Based Replication

Replication works because events written to the binary log are read
from the master and then processed on the slave. The events are
recorded within the binary log in different formats according the type
of event being recorded. The different replication formats used
correspond to the binary logging format used when the events were
recorded in the master's binary log. The correlation between binary
logging formats and the terms used during replication are:

   * Replication capabilities in MySQL originally were based on
     propagation of SQL statements from master to slave. This is called
     _statement-based replication_ (often abbreviated as _SBR_), which
     corresponds to the standard statement-based binary logging format.
     In older versions of MySQL (5.1.4 and earlier), binary logging and
     replication used this format exclusively.

   * Row-based binary logging logs changes in individual table rows.
     When used with MySQL replication, this is known as _row-based
     replication_ (often abbreviated as _RBR_). In row-based
     replication, the master writes messages known as _events_ to the
     binary log that indicate how individual table rows are changed.

   * The binary logging format can be changed in real time according to
     the event being logged using _mixed-format logging_.

     When the mixed format is in effect, statement-based logging is
     used by default, but automatically switches to row-based logging
     in particular cases as described below. Replication using the
     mixed format is often referred to as _mixed-based replication_ or
     _mixed-format replication_. For more information, see *Note
     binary-log-mixed::.

The mixed format is the default for MySQL replication.

The binary logging format is determined in part by the storage engine
being used and the statement being executed. For more information on
mixed-format logging and the rules governing the support of different
logging formats, see *Note binary-log-mixed::.

You must have the `SUPER' privilege to set the binary logging format on
the global level. Starting with MySQL 6.0.8, you must also have the
`SUPER' privilege to set the binary logging format for the current
session. (Bug#39106 (http://bugs.mysql.com/39106))

The logging format in a running MySQL server is controlled by setting
the `binlog_format' server system variable. This variable can be set
with session or global scope. The rules governing when and how the new
setting takes effect are the same as for other MySQL server system
variables -- setting the variable for the current session lasts only
until the end of that session, and the change is not visible to other
sessions; setting the variable globally requires a restart of the
server in order to take effect. For more information, see *Note
set-option::.

The statement-based and row-based replication formats have different
issues and limitations. For a comparison of their relative advantages
and disadvantages, see *Note replication-sbr-rbr::.

With statement-based replication, you may encounter issues with
replicating stored routines or triggers. You can avoid these issues by
using row-based replication instead. For more information, see *Note
stored-programs-logging::.

If you build MySQL from source, row-based replication is available by
default unless you invoke `configure' with the
`--without-row-based-replication' option.

For MySQL 5.1.20 and later (and MySQL 5.0.46 for backwards
compatibility), the following session variables are written to the
binary log and honored by the replication slave when parsing the binary
log:

   * `sql_mode'

   * `foreign_key_checks'

   * `unique_checks'

   * `character_set_client'

   * `collation_connection'

   * `collation_database'

   * `collation_server'

   * `sql_auto_is_null'

*Important*:

Even though session variables relating to character sets and collations
are written to the binary log, replication between different character
sets is not supported.


File: manual.info,  Node: replication-sbr-rbr,  Next: replication-rbr-usage,  Prev: replication-formats,  Up: replication-formats

16.1.2.1 Comparison of Statement-Based and Row-Based Replication
................................................................

Each binary logging format has advantages and disadvantages. For most
users, the mixed replication format should provide the best combination
of data integrity and performance. If, however, you want to take
advantage of the features specific to the statement-based or row-based
replication format when performing certain tasks, then you can use the
information in this section, which provides a summary of their relative
advantages and disadvantages, to determine which is best for your needs.

*Advantages of statement-based replication:*

   * Proven technology that has existed in MySQL since 3.23.

   * Less data written to log files. When updates or deletes affect
     many rows, this results in _much_ less storage space required for
     log files. This also means that taking and restoring from backups
     can be accomplished more quickly.

   * Log files contain all statements that made any changes, so they
     can be used to audit the database.

   * Tables replicated using statement-based replication are not
     required to have explicit primary keys.

*Disadvantages of statement-based replication:*

   * Statements which are unsafe for SBR

     Not all statements which modify data (such as *Note `INSERT':
     insert.  *Note `DELETE': delete, *Note `UPDATE': update, and
     `REPLACE' statements) can be replicated using statement-based
     replication. Any non-deterministic behavior is difficult to
     replicate when using statement-based replication. Examples of such
     DML (Data Modification Language) statements include the following:

        * A statement that depends on a UDF or stored program that is
          non-deterministic, since the value returned by such a UDF or
          stored program or depends on factors other than the
          parameters supplied to it. (Row-based replication, however,
          simply replicates the value returned by the UDF or stored
          program, so its effect on table rows and data is the same on
          both the master and slave.) See *Note
          replication-features-invoked::, for more information.

        * *Note `DELETE': delete. and *Note `UPDATE': update.
          statements that use a `LIMIT' clause without an `ORDER BY'
          are also non-deterministic.  See *Note
          replication-features-limit::.

        * Statements using any of the following functions cannot be
          replicated properly using statement-based replication:

             * `LOAD_FILE()'

             * `UUID()', `UUID_SHORT()'

             * `USER()'

             * `FOUND_ROWS()'

             * `SYSDATE()' (unless the server is started with the
               `--sysdate-is-now' option)

          However, all other functions are replicated correctly using
          statement-based replication, including `RAND()', `NOW()',
          *Note `LOAD DATA INFILE': load-data, and so forth.

          For more information, see *Note
          replication-features-functions::.

     When using statement-based replication, statements that cannot be
     replicated correctly using statement-based mode are logged with a
     warning like the one shown here:

          090213 16:58:54 [Warning] Statement is not safe to log in statement format.

     A similar warning is also issued to the client in such cases.

   * *Note `INSERT ... SELECT': insert. requires a greater number of
     row-level locks than with row-based replication.

   * *Note `UPDATE': update. statements that require a table scan
     (because no index is used in the `WHERE' clause) must lock a
     greater number of rows than with row-based replication.

   * For `InnoDB': An *Note `INSERT': insert. statement that uses
     `AUTO_INCREMENT' blocks other non-conflicting *Note `INSERT':
     insert.  statements.

   * For complex statements, the statement must be evaluated and
     executed on the slave before the rows are updated or inserted.
     With row-based replication, the slave only has to run the
     statement to apply the differences, not the full statement.

   * Stored functions execute with the same `NOW()' value as the calling
     statement. However, this is not true of stored procedures.

   * Deterministic UDFs must be applied on the slaves.

   * If there is an error in evaluation on the slave, particularly when
     executing complex statements, then using statement-based
     replication may slowly increase the margin of error across the
     affected rows over time. See *Note
     replication-features-slaveerrors::.

   * Tables must be (nearly) identical on master and slave. See *Note
     replication-features-differing-tables::, for more information.

*Advantages of row-based replication:*

   * All changes can be replicated. This is the safest form of
     replication.

     The `mysql' database is not replicated. The `mysql' database is
     instead seen as a node-specific database. Row-based replication is
     not supported on tables in this database. Instead, statements that
     would normally update this information -- such as *Note `GRANT':
     grant, *Note `REVOKE': revoke. and the manipulation of triggers,
     stored routines (including stored procedures), and views -- are
     all replicated to slaves using statement-based replication.

     For statements like `CREATE ... SELECT', a `CREATE' statement is
     generated from the table definition and replicated using the
     statement-based format, while the row insertions are replicated
     using the row-based format.

   * The technology is the same as in most other database management
     systems; knowledge about other systems transfers to MySQL.

   * Fewer locks are needed (and thus higher concurrency) on the master
     for the following types of statements:

        * *Note `INSERT ... SELECT': insert-select.

        * *Note `INSERT': insert. statements with `AUTO_INCREMENT'

        * *Note `UPDATE': update. or *Note `DELETE': delete. statements
          with `WHERE' clauses that don't use keys or don't change most
          of the examined rows.

   * Fewer locks are required on the slave for any *Note `INSERT':
     insert, *Note `UPDATE': update, or *Note `DELETE': delete.
     statement.

*Disadvantages of row-based replication:*

   * RBR tends to generate more data that must be logged. This is
     because, when using row-based replication to replicate a DML
     statement (such as an *Note `UPDATE': update.  or *Note `DELETE':
     delete. statement), each changed row must be written to the binary
     log. (When using statement-based replication, only the statement
     is written to the binary log.) This means that, if the statement
     changes many rows, row-based replication may write significantly
     more data to the binary log; this is true even for statements that
     are rolled back. This also means that taking and restoring from
     backup can require more time. In addition, the binary log is
     locked for a longer time to write the data, which may cause
     concurrency problems.

   * All tables replicated using row-based replication must have
     explicit primary keys.

   * Deterministic UDFs that generate large *Note `BLOB': blob. values
     take longer to replicate with row-based replication than with
     statement-based replication. This is because, when using row-based
     replication, the *Note `BLOB': blob. column data is itself logged,
     rather than the statement generating the data.

   * You cannot examine the logs to see what statements were executed,
     nor can you see on the slave what statements were received from
     the master and executed.

     However, beginning with MySQL 6.0.7, you can see what data was
     changed using *Note `mysqlbinlog': mysqlbinlog. with the options
     `--base64-output=DECODE-ROWS' and `--verbose'.

   * When performing a bulk operation that includes non-transactional
     storage engines, changes are applied as the statement executes.
     With row-based replication logging, this means that the binary log
     is written while the statement is running. On the master, this
     does not cause problems with concurrency, because tables are
     locked until the bulk operation terminates. On the slave server,
     however, tables are not locked while the slave applies changes,
     because the slave does not know that those changes are part of a
     bulk operation.

     In such cases, if you retrieve data from a table on the master
     (for example, using `SELECT * FROM table_name'), the server waits
     for the bulk operation to complete before executing the *Note
     `SELECT': select. statement, because the table is read-locked. On
     the slave, the server does not wait (because there is no lock).
     This means that, until the bulk operation on the slave has
     completed, you obtain different results for the same *Note
     `SELECT': select.  query on the master and on the slave.

     This behavior is expected to change in a future MySQL release;
     however, until it changes, you may prefer to use statement-based
     replication when your application requires concurrent large bulk
     inserts and selects.


File: manual.info,  Node: replication-rbr-usage,  Prev: replication-sbr-rbr,  Up: replication-formats

16.1.2.2 Usage of Row-based Logging and Row-Based Replication
.............................................................

Using row-based logging or replication, rather than statement-based
logging or replication, can result in major changes in the replication
environment and in the behavior of applications. This section describes
a number of issues known to exist when using row-based logging or
row-based replication, and discusses some best practices for taking
advantage of row-based logging (RBL) and row-based replication (RBR).

For additional information, see *Note replication-sbr-rbr::, and *Note
replication-formats::.

   * RBR and primary keys

     Currently, row-based replication may fail if any table to be
     replicated does not have an explicit primary key. This is a known
     issue which we are working to fix in a future MySQL release.

   * RBL, RBR, and temporary tables

     As noted elsewhere in this chapter (see *Note
     replication-features-temptables::), temporary tables are not
     replicated when using the row-based format. However, you can use
     the mixed format; when mixed format is in effect, `safe'
     statements involving temporary tables are logged using the
     statement-based format. For more information, see *Note
     replication-sbr-rbr::.

     *Note*:

     There is actually no need to replicate temporary tables when using
     RBR. In addition, since temporary tables can be read only from the
     thread which created them, there is seldom if ever any benefit
     obtained from replicating them, even when using statement-based
     mode.

   * RBL and the `BLACKHOLE' storage engine

     Prior to MySQL 6.0.7, *Note `DELETE': delete. and *Note `UPDATE':
     update. statements did not work with RBL and `BLACKHOLE' tables
     (Bug#38360 (http://bugs.mysql.com/38360)).

   * RBL and synchronization of non-transactional tables

     When using row-based replication of a `MyISAM' or other
     non-transactional table, changed rows are written to the
     transaction cache.  Often, when many rows are affected, the set of
     changes are split into several events; when the statement commits,
     all of these events are written to the binary log. When executing
     on the slave, a table lock is taken on all tables involved, then
     the rows are applied in batch mode.  (This may or may not be
     effective, depending on the engine used for the slave's copy of
     the table).

   * Latency and binary log size

     Because RBL writes changes for each row to the binary log, the
     size of the binary log can grow quite rapidly. When used in a
     replication environment, this can significantly increase the time
     required for making the changes on the slave that match those on
     the master. You should be aware of the potential for this delay in
     your applications.

   * Reading the binary log

     Formerly, *Note `mysqlbinlog': mysqlbinlog. was not able to format
     the contents of the binary log in a manner that was easily
     human-readable, which could cause problems if you wanted to read
     or recover from a replication or database failure using the
     contents of the binary log (Bug#31455
     (http://bugs.mysql.com/31455)).  This limitation was removed in
     MySQL 6.0.7, with the addition of the *Note `mysqlbinlog':
     mysqlbinlog.  `--base64-output=DECODE-ROWS' and `--verbose'
     options.  For more information, see *Note mysqlbinlog-row-events::.

   * Binary log execution errors and `slave_exec_mode'

     If you use `slave_exec_mode=IDEMPOTENT', a failure to apply
     changes from RBL because the original row cannot be found does not
     trigger an error, and does not cause replication to fail. This
     means that it is possible that updates are not applied on the
     slave, so that the master and slave are no longer synchronized.
     Latency issues and use of non-transactional tables when using
     `slave_exec_mode=IDEMPOTENT' and RBR can cause the master and
     slave to diverge even further. For more information about
     `slave_exec_mode'
     (http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_exec_mode),
     see *Note server-system-variables::.

     *Note*:

     `slave_exec_mode=IDEMPOTENT' is generally useful only for circular
     replication or multi-master replication with MySQL Cluster. For
     other scenarios, the default value (`slave_exec_mode=STRICT') is
     normally sufficient.

     The `NDBCLUSTER' storage engine is currently not supported in
     MySQL 6.0. MySQL Cluster users wishing to upgrade from MySQL 5.0
     should instead migrate to MySQL Cluster NDB 6.2 or 6.3; these are
     based on MySQL 5.1 but contain the latest improvements and fixes
     for `NDBCLUSTER'. For more information, see MySQL Cluster NDB
     6.X/7.X
     (http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html).

   * Lack of binary log checksums

     No checksums are used for RBL. This means that network, disk, and
     other errors may not be identified when processing the binary log.
     To ensure that data is transmitted without network corruption, you
     may want to consider using SSL, which adds another layer of
     checksumming, for replication connections. See *Note
     secure-connections::, for more information about setting up MySQL
     with SSL.

   * Filtering based on server ID

     A common practice is to filter out changes on some slaves by using
     a `WHERE' clause that includes the relation `@server_id <>
     SERVER-ID' clause with *Note `UPDATE': update. and DELETE
     statements, a simple example of such a clause being `WHERE
     @server_id <> 1'. However, this does not work correctly with
     row-based logging. If you must use the `server_id' system variable
     for statement filtering, then you must also use
     `--binlog_format=STATEMENT'.

     Beginning with MySQL 6.0.10, you can do filtering based on server
     ID by using the `IGNORE_SERVER_IDS' option for the *Note `CHANGE
     MASTER TO': change-master-to. statement. This option works with the
     statement-based and row-based logging formats.

   * Database-level replication options

     The effects of the options `--replicate-do-db',
     `--replicate-ignore-db', and `--replicate-rewrite-db' differ
     considerably depending on whether row-based or statement-based
     logging is in use. Because of this, we recommend that you avoid
     the database-level options and use the table-level options such as
     `--replicate-do-table' and `--replicate-ignore-table' instead. For
     more information about these options and the impact that your
     choice of replication format has on how they operate, see *Note
     replication-options::.


File: manual.info,  Node: replication-options,  Next: replication-administration,  Prev: replication-formats,  Up: replication-configuration

16.1.3 Replication and Binary Logging Options and Variables
-----------------------------------------------------------

* Menu:

* replication-options-table::    Replication and Binary Logging Option and Variable Reference
* replication-options-master::   Replication Master Options and Variables
* replication-options-slave::    Replication Slave Options and Variables
* replication-options-binary-log::  Binary Log Options and Variables

The next few sections contain information about *Note `mysqld': mysqld.
options and server variables that are used in replication and for
controlling the binary log. Options and variables for use on
replication masters and replication slaves are covered separately, as
are options and variables relating to binary logging. A set of
quick-reference tables providing basic information about these options
and variables is also included (in the next section following this one).

Of particular importance is the `--server-id' option.

*Command Line Format*  `--server-id=#'
*Config File Format*   `server-id'
*Option Sets Variable* Yes, `server_id'
*Variable Name*        `server_id'
*Variable Scope*       Global
*Dynamic Variable*     Yes
*Value Set *           
Typenumeric Default0   
Range0-4294967295      

This option is common to both master and slave replication servers, and
is used in replication to enable master and slave servers to identify
themselves uniquely. For additional information, see *Note
replication-options-master::, and *Note replication-options-slave::.

On the master and each slave, you _must_ use the `--server-id' option
to establish a unique replication ID in the range from 1 to 2^32 - 1;
by `unique', we mean that each ID must be different from every other ID
in use by any other replication master or slave. Example: `server-id=3'.

If you omit `--server-id', it assumes the default value 0, in which
case a master refuses connections from all slaves, and a slave refuses
to connect to a master. See *Note replication-howto-slavebaseconfig::,
for more information.


File: manual.info,  Node: replication-options-table,  Next: replication-options-master,  Prev: replication-options,  Up: replication-options

16.1.3.1 Replication and Binary Logging Option and Variable Reference
.....................................................................

The following tables list basic information about the MySQL
command-line options and system variables applicable to replication and
the binary log.

*`mysqld' Replication Option/Variable Summary*

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
abort-slave-event-count       Yes                                                        Yes                                                                                                                                                                                                                                         
Com_change_master                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_show_master_status                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_new_master                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_show_slave_hosts                                                                                                                                                                                           Yes                                                        Both                                                       No
Com_show_slave_status                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_slave_start                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_slave_stop                                                                                                                                                                                                 Yes                                                        Both                                                       No
disconnect-slave-event-count  Yes                                                        Yes                                                                                                                                                                                                                                         
init_slave                    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
log-slave-updates             Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
log_slave_updates                                                                                                                                                                                                                                                                                                                    
*Note master-bind:            Yes                                                        Yes                                                        Yes                                                                                                                                                                              No
replication-options.                                                                                                                                                                                                                                                                                                                 
master-info-file              Yes                                                        Yes                                                                                                                                                                                                                                         
master-retry-count            Yes                                                        Yes                                                                                                                                                                                                                                         
relay-log                     Yes                                                        Yes                                                                                                                                                                                                                                         
relay-log-index               Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_: relay_log_index                                                                                                                                                                                                                                                                                                        
relay_log_purge               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
relay_log_recovery            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
replicate-do-db               Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-do-table            Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-ignore-db           Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-ignore-table        Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-rewrite-db          Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-same-server-id      Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-wild-do-table       Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-wild-ignore-table   Yes                                                        Yes                                                                                                                                                                                                                                         
report-host                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_host                                                                                                                           Yes                                                                                                                   Global                                                     No
report-password               Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_password                                                                                                                       Yes                                                                                                                   Global                                                     No
report-port                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_port                                                                                                                           Yes                                                                                                                   Global                                                     No
report-user                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_user                                                                                                                           Yes                                                                                                                   Global                                                     No
rpl_recovery_rank                                                                                                                                   Yes                                                                                                                   Global                                                     Yes
Rpl_semi_sync_master_clients                                                                                                                                                                                   Yes                                                        Global                                                     No
rpl_semi_sync_master_enabled                                                                                                                        Yes                                                                                                                   Global                                                     Yes
Rpl_semi_sync_master_net_avg_wait_time                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_net_wait_time                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_net_waits                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_no_times                                                                                                                                                                                  Yes                                                        Global                                                     No
Rpl_semi_sync_master_no_tx                                                                                                                                                                                     Yes                                                        Global                                                     No
rpl_semi_sync_master_reply_log_file_pos                                                                                                                      Yes                                                                                                                   Global                                                     Yes
Rpl_semi_sync_master_status                                                                                                                                                                                    Yes                                                        Global                                                     No
Rpl_semi_sync_master_timefunc_failures                                                                                                                                                                                 Yes                                                        Global                                                     No
rpl_semi_sync_master_timeout                                                                                                                        Yes                                                                                                                   Global                                                     Yes
rpl_semi_sync_master_trace_level                                                                                                                      Yes                                                                                                                   Global                                                     Yes
Rpl_semi_sync_master_tx_avg_wait_time                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_tx_wait_time                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_tx_waits                                                                                                                                                                                  Yes                                                        Global                                                     No
Rpl_semi_sync_master_wait_pos_backtraverse                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_wait_sessions                                                                                                                                                                                 Yes                                                        Global                                                     No
Rpl_semi_sync_master_yes_tx                                                                                                                                                                                    Yes                                                        Global                                                     No
rpl_semi_sync_slave_enabled                                                                                                                         Yes                                                                                                                   Global                                                     Yes
Rpl_semi_sync_slave_status                                                                                                                                                                                     Yes                                                        Global                                                     No
rpl_semi_sync_slave_trace_level                                                                                                                      Yes                                                                                                                   Global                                                     Yes
Rpl_status                                                                                                                                                                                                     Yes                                                        Global                                                     No
show-slave-auth-info          Yes                                                        Yes                                                                                                                                                                                                                                         
*Note skip-slave-start:       Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
slave_compressed_protocol     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
slave_exec_mode                                                                                                                                     Yes                                                                                                                   Global                                                     Yes
Slave_heartbeat_period                                                                                                                                                                                         Yes                                                        Global                                                     No
*Note slave-load-tmpdir:      Yes                                                        Yes                                                                                                                                                                              Global                                                     No
replication-options.                                                                                                                                                                                                                                                                                                                 
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
slave_load_tmpdir                                                                                                                                                                                                                                                                                                                    
slave-net-timeout             Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
slave_net_timeout                                                                                                                                                                                                                                                                                                                    
Slave_open_temp_tables                                                                                                                                                                                         Yes                                                        Global                                                     No
Slave_received_heartbeats                                                                                                                                                                                      Yes                                                        Global                                                     No
Slave_retried_transactions                                                                                                                                                                                     Yes                                                        Global                                                     No
Slave_running                                                                                                                                                                                                  Yes                                                        Global                                                     No
slave-skip-errors             Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
slave_skip_errors                                                                                                                                                                                                                                                                                                                    
slave_transaction_retries     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
sql_slave_skip_counter                                                                                                                              Yes                                                                                                                   Global                                                     Yes

*Note replication-options-master::, provides more detailed information
about options and variables relating to replication master servers. For
more information about options and variables relating to replication
slaves *Note replication-options-slave::.

*`mysqld' Binary Logging Option/Variable Summary*

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
Binlog_cache_disk_use                                                                                                                                                                                          Yes                                                        Global                                                     No
binlog_cache_size             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Binlog_cache_use                                                                                                                                                                                               Yes                                                        Global                                                     No
binlog-do-db                  Yes                                                        Yes                                                                                                                                                                                                                                         
binlog-format                 Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: binlog_format                                                                                                                         Yes                                                                                                                   Both                                                       Yes
binlog-ignore-db              Yes                                                        Yes                                                                                                                                                                                                                                         
binlog-row-event-max-size     Yes                                                        Yes                                                                                                                                                                                                                                         
Com_show_binlog_events                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_binlogs                                                                                                                                                                                               Yes                                                        Both                                                       No
max_binlog_cache_size         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max-binlog-dump-events        Yes                                                        Yes                                                                                                                                                                                                                                         
max_binlog_size               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
sporadic-binlog-dump-fail     Yes                                                        Yes                                                                                                                                                                                                                                         

*Note replication-options-binary-log::, provides more detailed
information about options and variables relating to binary logging. For
additional general information about the binary log, see *Note
binary-log::.

For a table showing _all_ command-line options, system and status
variables used with *Note `mysqld': mysqld, see *Note
mysqld-option-tables::.


File: manual.info,  Node: replication-options-master,  Next: replication-options-slave,  Prev: replication-options-table,  Up: replication-options

16.1.3.2 Replication Master Options and Variables
.................................................

This section describes the server options and system variables that you
can use on replication master servers. You can specify the options
either on the *Note command line: command-line-options. or in an *Note
option file: option-files. You can specify system variable values using
*Note `SET': set-option.

On the master and each slave, you must use the `server-id' option to
establish a unique replication ID. For each server, you should pick a
unique positive integer in the range from 1 to 2^32 - 1, and each ID
must be different from every other ID in use by any other replication
master or slave. Example: `server-id=3'.

For options used on the master for controlling binary logging, see
*Note replication-options-binary-log::.

   *  `auto_increment_increment'

     *Command Line        `--auto_increment_increment[=#]'
     Format*              
     *Config File Format* `auto_increment_increment'
     *Option Sets         Yes, `auto_increment_increment'
     Variable*            
     *Variable Name*      `auto_increment_increment'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1             
     Range1-65535         

     `auto_increment_increment' and `auto_increment_offset' are
     intended for use with master-to-master replication, and can be
     used to control the operation of `AUTO_INCREMENT' columns. Both
     variables have global and session values, and each can assume an
     integer value between 1 and 65,535 inclusive. Setting the value of
     either of these two variables to 0 causes its value to be set to 1
     instead. Attempting to set the value of either of these two
     variables to an integer greater than 65,535 or less than 0 causes
     its value to be set to 65,535 instead. Attempting to set the value
     of `auto_increment_increment' or `auto_increment_offset' to a
     non-integer value gives rise to an error, and the actual value of
     the variable remains unchanged.

     These two variables affect `AUTO_INCREMENT' column behavior as
     follows:

        * `auto_increment_increment' controls the interval between
          successive column values.  For example:

               mysql> SHOW VARIABLES LIKE 'auto_inc%';
               +--------------------------+-------+
               | Variable_name            | Value |
               +--------------------------+-------+
               | auto_increment_increment | 1     |
               | auto_increment_offset    | 1     |
               +--------------------------+-------+
               2 rows in set (0.00 sec)

               mysql> CREATE TABLE autoinc1
                   -> (col INT NOT NULL AUTO_INCREMENT PRIMARY KEY);
                 Query OK, 0 rows affected (0.04 sec)

               mysql> SET @@auto_increment_increment=10;
               Query OK, 0 rows affected (0.00 sec)

               mysql> SHOW VARIABLES LIKE 'auto_inc%';
               +--------------------------+-------+
               | Variable_name            | Value |
               +--------------------------+-------+
               | auto_increment_increment | 10    |
               | auto_increment_offset    | 1     |
               +--------------------------+-------+
               2 rows in set (0.01 sec)

               mysql> INSERT INTO autoinc1 VALUES (NULL), (NULL), (NULL), (NULL);
               Query OK, 4 rows affected (0.00 sec)
               Records: 4  Duplicates: 0  Warnings: 0

               mysql> SELECT col FROM autoinc1;
               +-----+
               | col |
               +-----+
               |   1 |
               |  11 |
               |  21 |
               |  31 |
               +-----+
               4 rows in set (0.00 sec)

          (Note how *Note `SHOW VARIABLES': show-variables. is used
          here to obtain the current values for these variables.)

        * `auto_increment_offset' determines the starting point for the
          `AUTO_INCREMENT' column value. Consider the following,
          assuming that these statements are executed during the same
          session as the example given in the description for
          `auto_increment_increment':

               mysql> SET @@auto_increment_offset=5;
               Query OK, 0 rows affected (0.00 sec)

               mysql> SHOW VARIABLES LIKE 'auto_inc%';
               +--------------------------+-------+
               | Variable_name            | Value |
               +--------------------------+-------+
               | auto_increment_increment | 10    |
               | auto_increment_offset    | 5     |
               +--------------------------+-------+
               2 rows in set (0.00 sec)

               mysql> CREATE TABLE autoinc2
                   -> (col INT NOT NULL AUTO_INCREMENT PRIMARY KEY);
               Query OK, 0 rows affected (0.06 sec)

               mysql> INSERT INTO autoinc2 VALUES (NULL), (NULL), (NULL), (NULL);
               Query OK, 4 rows affected (0.00 sec)
               Records: 4  Duplicates: 0  Warnings: 0

               mysql> SELECT col FROM autoinc2;
               +-----+
               | col |
               +-----+
               |   5 |
               |  15 |
               |  25 |
               |  35 |
               +-----+
               4 rows in set (0.02 sec)

          If the value of `auto_increment_offset' is greater than that
          of `auto_increment_increment', the value of
          `auto_increment_offset' is ignored.

     Should one or both of these variables be changed and then new rows
     inserted into a table containing an `AUTO_INCREMENT' column, the
     results may seem counterintuitive because the series of
     `AUTO_INCREMENT' values is calculated without regard to any values
     already present in the column, and the next value inserted is the
     least value in the series that is greater than the maximum
     existing value in the `AUTO_INCREMENT' column. In other words, the
     series is calculated like so:

     `auto_increment_offset + N x auto_increment_increment'

     where N is a positive integer value in the series [1, 2, 3, ...].
     For example:

          mysql> SHOW VARIABLES LIKE 'auto_inc%';
          +--------------------------+-------+
          | Variable_name            | Value |
          +--------------------------+-------+
          | auto_increment_increment | 10    |
          | auto_increment_offset    | 5     |
          +--------------------------+-------+
          2 rows in set (0.00 sec)

          mysql> SELECT col FROM autoinc1;
          +-----+
          | col |
          +-----+
          |   1 |
          |  11 |
          |  21 |
          |  31 |
          +-----+
          4 rows in set (0.00 sec)

          mysql> INSERT INTO autoinc1 VALUES (NULL), (NULL), (NULL), (NULL);
          Query OK, 4 rows affected (0.00 sec)
          Records: 4  Duplicates: 0  Warnings: 0

          mysql> SELECT col FROM autoinc1;
          +-----+
          | col |
          +-----+
          |   1 |
          |  11 |
          |  21 |
          |  31 |
          |  35 |
          |  45 |
          |  55 |
          |  65 |
          +-----+
          8 rows in set (0.00 sec)

     The values shown for `auto_increment_increment' and
     `auto_increment_offset' generate the series 5 + N x 10, that is,
     [5, 15, 25, 35, 45, ...]. The greatest value present in the `col'
     column prior to the *Note `INSERT': insert. is 31, and the next
     available value in the `AUTO_INCREMENT' series is 35, so the
     inserted values for `col' begin at that point and the results are
     as shown for the *Note `SELECT': select. query.

     It is not possible to confine the effects of these two variables
     to a single table, and thus they do not take the place of the
     sequences offered by some other database management systems; these
     variables control the behavior of all `AUTO_INCREMENT' columns in
     _all_ tables on the MySQL server. If the global value of either
     variable is set, its effects persist until the global value is
     changed or overridden by setting the session value, or until *Note
     `mysqld': mysqld. is restarted. If the local value is set, the new
     value affects `AUTO_INCREMENT' columns for all tables into which
     new rows are inserted by the current user for the duration of the
     session, unless the values are changed during that session.

     The default value of `auto_increment_increment' is 1. See *Note
     replication-features-auto-increment::.

   *  `auto_increment_offset'

     *Command Line        `--auto_increment_offset[=#]'
     Format*              
     *Config File Format* `auto_increment_offset'
     *Option Sets         Yes, `auto_increment_offset'
     Variable*            
     *Variable Name*      `auto_increment_offset'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1             
     Range1-65535         

     This variable has a default value of 1. For particulars, see the
     description for `auto_increment_increment'.


File: manual.info,  Node: replication-options-slave,  Next: replication-options-binary-log,  Prev: replication-options-master,  Up: replication-options

16.1.3.3 Replication Slave Options and Variables
................................................

This section describes the server options and system variables that you
can use on slave replication servers. You can specify the options
either on the *Note command line: command-line-options. or in an *Note
option file: option-files. Many of the options can be reset while the
server is running by using the *Note `CHANGE MASTER TO':
change-master-to. statement. You can specify system variable values
using *Note `SET': set-option.

Server ID

On the master and each slave, you must use the `server-id' option to
establish a unique replication ID. For each server, you should pick a
unique positive integer in the range from 1 to 2^32 - 1, and each ID
must be different from every other ID. Example: `server-id=3'.

The `master.info' file format in MySQL 6.0 includes values
corresponding to the SSL options.  In addition, the file format
includes as its first line the number of lines in the file. (See *Note
slave-logs::.) If you upgrade an older server (before MySQL 4.1.1) to a
newer version, the new server upgrades the `master.info' file to the
new format automatically when it starts. However, if you downgrade a
newer server to an older version, you should remove the first line
manually before starting the older server for the first time.

If no `master.info' file exists when the slave server starts, it uses
the values for those options that are specified in option files or on
the command line. This occurs when you start the server as a
replication slave for the very first time, or when you have run *Note
`RESET SLAVE': reset-slave. and then have shut down and restarted the
slave.

If the `master.info' file exists when the slave server starts, the
server uses its contents and ignores any options that correspond to the
values listed in the file. Thus, if you start the slave server with
different values of the startup options that correspond to values in the
`master.info' file, the different values have no effect, because the
server continues to use the `master.info' file. To use different values,
you must either restart after removing the `master.info' file or
(preferably) use the *Note `CHANGE MASTER TO': change-master-to.
statement to reset the values while the slave is running.

Suppose that you specify this option in your `my.cnf' file:

     [mysqld]
     master-host=SOME_HOST

The first time you start the server as a replication slave, it reads
and uses that option from the `my.cnf' file. The server then records
the value in the `master.info' file. The next time you start the
server, it reads the master host value from the `master.info' file only
and ignores the value in the option file. If you modify the `my.cnf'
file to specify a different master host of SOME_OTHER_HOST, the change
still has no effect. You should use *Note `CHANGE MASTER TO':
change-master-to. instead.

This example shows a more extensive use of startup options to configure
a slave server:

     [mysqld]
     server-id=2
     master-host=db-master.mycompany.com
     master-port=3306
     master-user=pertinax
     master-password=freitag
     master-connect-retry=60
     report-host=db-slave.mycompany.com

*Note*:

Because the server gives an existing `master.info' file precedence over
the startup options just described, you might prefer not to use startup
options for these values at all, and instead to specify them by using
the *Note `CHANGE MASTER TO': change-master-to. statement. See *Note
change-master-to::.

Startup options for replication slaves

The following list describes startup options for controlling
replication slaves. Many of these options can be reset while the server
is running by using the *Note `CHANGE MASTER TO': change-master-to.
statement. Others, such as the `--replicate-*' options, can be set only
when the slave server starts. Replication-related system variables are
discussed later in this section.

   *  `--log-slave-updates'

     Normally, a slave does not log to its own binary log any updates
     that are received from a master server. This option tells the
     slave to log the updates performed by its SQL thread to its own
     binary log. For this option to have any effect, the slave must
     also be started with the `--log-bin' option to enable binary
     logging.  `--log-slave-updates' is used when you want to chain
     replication servers. For example, you might want to set up
     replication servers using this arrangement:

          A -> B -> C

     Here, `A' serves as the master for the slave `B', and `B' serves
     as the master for the slave `C'. For this to work, `B' must be
     both a master _and_ a slave. You must start both `A' and `B' with
     `--log-bin' to enable binary logging, and `B' with the
     `--log-slave-updates' option so that updates received from `A' are
     logged by `B' to its binary log.

   *  `--log-slow-slave-statements'

     *Version Introduced* 6.0.4
     *Command Line        `--log-slow-slave-statements'
     Format*              
     *Config File Format* `log-slow-slave-statements'
     *Value Set *         
     Typeboolean          
     Defaultoff           

     When the slow query log is enabled, this option enables logging
     for queries that have taken more than `long_query_time' seconds to
     execute on the slave.

     This option was added in MySQL 6.0.4.

   * `--log-warnings[=LEVEL]'

     This option causes a server to print more messages to the error
     log about what it is doing. With respect to replication, the
     server generates warnings that it succeeded in reconnecting after
     a network/connection failure, and informs you as to how each slave
     thread started. This option is enabled by default; to disable it,
     use `--skip-log-warnings'.  Aborted connections are not logged to
     the error log unless the value is greater than 1.

     Note that the effects of this option are not limited to
     replication. It produces warnings across a spectrum of server
     activities.

   *  `--master-info-file=FILE_NAME'

     The name to use for the file in which the slave records
     information about the master. The default name is `master.info' in
     the data directory.

   *  `--master-retry-count=COUNT'

     The number of times that the slave tries to connect to the master
     before giving up. Reconnects are attempted at intervals set by
     `--master-connect-retry'
     (http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#option_mysqld_master-connect-retry)
     and reconnects are triggered when data reads by the slave time out
     according to the `--slave-net-timeout' option. The default value
     is 86400.

     You can also set the retry count by using the
     `MASTER_CONNECT_RETRY' option for the *Note `CHANGE MASTER TO':
     change-master-to. statement.

   *  `--max-relay-log-size=SIZE'

     The size at which the server rotates relay log files
     automatically. For more information, see *Note slave-logs::. The
     default size is 1GB.

   *  `--read-only'

     Cause the slave to allow no updates except from slave threads or
     from users having the `SUPER' privilege. On a slave server, this
     can be useful to ensure that the slave accepts updates only from
     its master server and not from clients. This variable does not
     apply to `TEMPORARY' tables.

   *  `--relay-log=FILE_NAME'

     The basename for the relay log. The default basename is
     `HOST_NAME-relay-bin'.  The server creates relay log files in
     sequence by adding a numeric suffix to the basename.

     Due to the manner in which MySQL parses server options, if you
     specify this option, you must supply a value; _the default
     basename is used only if the option is not actually specified_. If
     you use the `--relay-log' option without specifying a value,
     unexpected behavior is likely to result; this behavior depends on
     the other options used, the order in which they are specified, and
     whether they are specified on the command line or in an option
     file. For more information about how MySQL handles server options,
     see *Note program-options::.

     If you specify this option, the value specified is also used as
     the basename for the relay log index file. You can override this
     behavior by specifying a different relay log index file basename
     using the `--relay-log-index' option.

     You may find the `--relay-log' option useful in performing the
     following tasks:

        * Creating relay logs whose names are independent of host names.

        * If you need to put the relay logs in some area other than the
          data directory, because your relay logs tend to be very large
          and you do not want to decrease `max_relay_log_size'.

        * To increase speed by using load-balancing between disks.

   *  `--relay-log-index=FILE_NAME'

     The name to use for the relay log index file. The default name is
     `HOST_NAME-relay-bin.index' in the data directory, where HOST_NAME
     is the name of the slave server.

     Due to the manner in which MySQL parses server options, if you
     specify this option, you must supply a value; _the default
     basename is used only if the option is not actually specified_. If
     you use the `--relay-log-index' option without specifying a value,
     unexpected behavior is likely to result; this behavior depends on
     the other options used, the order in which they are specified, and
     whether they are specified on the command line or in an option
     file. For more information about how MySQL handles server options,
     see *Note program-options::.

     If you specify this option, the value specified is also used as
     the basename for the relay logs. You can override this behavior by
     specifying a different relay log file basename using the
     `--relay-log' option.

   *  `--relay-log-info-file=FILE_NAME'

     The name to use for the file in which the slave records
     information about the relay logs. The default name is
     `relay-log.info' in the data directory.

   *  `--relay-log-purge={0|1}'

     Disable or enable automatic purging of relay logs as soon as they
     are no longer needed. The default value is 1 (enabled).  This is a
     global variable that can be changed dynamically with `SET GLOBAL
     relay_log_purge = N'.

   *  `--relay-log-recovery={0|1}'

     Enables automatic relay log recovery immediately following server
     startup, which means that the replication slave discards all
     unprocessed relay logs and retrieves them from the replication
     master. This should be used following a crash on the replication
     slave to insure that no possibly corrupted relay logs are
     processed. The default value is 0 (disabled).

   *  `--relay-log-space-limit=SIZE'

     This option places an upper limit on the total size in bytes of
     all relay logs on the slave. A value of 0 means `no limit.' This
     is useful for a slave server host that has limited disk space.
     When the limit is reached, the I/O thread stops reading binary log
     events from the master server until the SQL thread has caught up
     and deleted some unused relay logs. Note that this limit is not
     absolute: There are cases where the SQL thread needs more events
     before it can delete relay logs. In that case, the I/O thread
     exceeds the limit until it becomes possible for the SQL thread to
     delete some relay logs, because not doing so would cause a
     deadlock. You should not set `--relay-log-space-limit' to less
     than twice the value of `--max-relay-log-size' (or
     `--max-binlog-size' if `--max-relay-log-size' is 0). In that case,
     there is a chance that the I/O thread waits for free space because
     `--relay-log-space-limit' is exceeded, but the SQL thread has no
     relay log to purge and is unable to satisfy the I/O thread. This
     forces the I/O thread to ignore `--relay-log-space-limit'
     temporarily.

   *  `--replicate-do-db=DB_NAME'

     The effects of this option depend on whether statement-based or
     row-based replication is in use.

     Statement-based replication

     Tell the slave to restrict replication to statements where the
     default database (that is, the one selected by *Note `USE': use.)
     is DB_NAME. To specify more than one database, use this option
     multiple times, once for each database; however, doing so does
     _not_ replicate cross-database statements such as `UPDATE
     SOME_DB.SOME_TABLE SET foo='bar'' while a different database (or no
     database) is selected.

     *Warning*:

     To specify multiple databases you _must_ use multiple instances of
     this option. Because database names can contain commas, if you
     supply a comma separated list then the list will be treated as the
     name of a single database.

     An example of what does not work as you might expect when using
     statement-based replication: If the slave is started with
     `--replicate-do-db=sales' and you issue the following statements
     on the master, the *Note `UPDATE': update. statement is _not_
     replicated:

          USE prices;
          UPDATE sales.january SET amount=amount+1000;

     The main reason for this `check just the default database'
     behavior is that it is difficult from the statement alone to know
     whether it should be replicated (for example, if you are using
     multiple-table *Note `DELETE': delete. statements or
     multiple-table *Note `UPDATE': update.  statements that act across
     multiple databases). It is also faster to check only the default
     database rather than all databases if there is no need.

     Row-based replication

     Tells the slave to restrict replication to database DB_NAME. Only
     tables belonging to DB_NAME are changed; the current database has
     no effect on this. For example, suppose that the slave is started
     with `--replicate-do-db=sales' and row-based replication is in
     effect, and then the following statements are run on the master:

          USE prices;
          UPDATE sales.february SET amount=amount+100;

     The `february' table in the `sales' database on the slave is
     changed in accordance with the *Note `UPDATE': update.  statement;
     this occurs whether or not the *Note `USE': use. statement was
     issued.  However, issuing the following statements on the master
     has no effect on the slave when using row-based replication and
     `--replicate-do-db=sales':

          USE prices;
          UPDATE prices.march SET amount=amount-25;

     Even if the statement `USE prices' were changed to `USE sales', the
     *Note `UPDATE': update. statement's effects would still not be
     replicated.

     Another important difference in how `--replicate-do-db' is handled
     in statement-based replication as opposed to row-based replication
     occurs with regard to statements that refer to multiple databases.
     Suppose the slave is started with `--replicate-do-db=db1', and the
     following statements are executed on the master:

          USE db1;
          UPDATE db1.table1 SET col1 = 10, db2.table2 SET col2 = 20;

     If you are using statement-based replication, then both tables are
     updated on the slave. However, when using row-based replication,
     only `table1' is affected on the slave; since `table2' is in a
     different database, `table2' on the slave is not changed by the
     *Note `UPDATE': update. Now suppose that, instead of the `USE db1'
     statement, a `USE db4' statement had been used:

          USE db4;
          UPDATE db1.table1 SET col1 = 10, db2.table2 SET col2 = 20;

     In this case, the *Note `UPDATE': update.  statement would have no
     effect on the slave when using statement-based replication.
     However, if you are using row-based replication, the *Note
     `UPDATE': update. would change `table1' on the slave, but not
     `table2' -- in other words, only tables in the database named by
     `--replicate-do-db' are changed, and the choice of current
     database has no effect on this behavior.

     If you need cross-database updates to work, use
     `--replicate-wild-do-table=DB_NAME.%' instead. See *Note
     replication-rules::.

     *Note*:

     This option effects replication in the same manner that
     `--binlog-do-db' affects binary logging, and the affects of the
     replication format on how `--replicate-do-db' affects replication
     behavior are the same as those of the logging format on the
     behavior of `--binlog-do-db'.

   *  `--replicate-ignore-db=DB_NAME'

     As with `--replicate-do-db', the effects of this option depend on
     whether statement-based or row-based replication is in use.

     Statement-based replication

     Tells the slave to not replicate any statement where the default
     database (that is, the one selected by *Note `USE': use.) is
     DB_NAME.

     Row-based replication

     Tells the slave not to update any tables in the database DB_NAME.
     The current database has no effect.

     When using statement-based replication, the following example does
     not work as you might expect. Suppose that the slave is started
     with `--replicate-ignore-db=sales' and you issue the following
     statements on the master:

          USE prices;
          UPDATE sales.january SET amount=amount+1000;

     The *Note `UPDATE': update. statement _is_ replicated in such a
     case because `--replicate-ignore-db' applies only to the default
     database (determined by the *Note `USE': use. statement). Because
     the `sales' database was specified explicitly in the statement,
     the statement has not been filtered. However, when using row-based
     replication, the *Note `UPDATE': update. statement's effects are
     _not_ propagated to the slave, and the slave's copy of the
     `sales.january' table is unchanged; in this instance,
     `--replicate-ignore-db=sales' causes _all_ changes made to tables
     in the master's copy of the `sales' database to be ignored by the
     slave.

     To specify more than one database to ignore, use this option
     multiple times, once for each database. Because database names can
     contain commas, if you supply a comma separated list then the list
     will be treated as the name of a single database.

     You should not use this option if you are using cross-database
     updates and you do not want these updates to be replicated.  See
     *Note replication-rules::.

     If you need cross-database updates to work, use
     `--replicate-wild-ignore-table=DB_NAME.%' instead. See *Note
     replication-rules::.

     *Note*:

     This option effects replication in the same manner that
     `--binlog-ignore-db' affects binary logging, and the affects of
     the replication format on how `--replicate-ignore-db' affects
     replication behavior are the same as those of the logging format
     on the behavior of `--binlog-ignore-db'.

   *  `--replicate-do-table=DB_NAME.TBL_NAME'

     Tells the slave thread to restrict replication to the specified
     table. To specify more than one table, use this option multiple
     times, once for each table. This works for cross-database updates,
     in contrast to `--replicate-do-db'. See *Note replication-rules::.

   *  `--replicate-ignore-table=DB_NAME.TBL_NAME'

     Tells the slave thread to not replicate any statement that updates
     the specified table, even if any other tables might be updated by
     the same statement. To specify more than one table to ignore, use
     this option multiple times, once for each table. This works for
     cross-database updates, in contrast to `--replicate-ignore-db'. See
     *Note replication-rules::.

   *  `--replicate-rewrite-db=FROM_NAME->TO_NAME'

     Tells the slave to translate the default database (that is, the
     one selected by *Note `USE': use.) to TO_NAME if it was FROM_NAME
     on the master. Only statements involving tables are affected (not
     statements such as *Note `CREATE DATABASE': create-database, *Note
     `DROP DATABASE': drop-database, and *Note `ALTER DATABASE':
     alter-database.), and only if FROM_NAME is the default database on
     the master. This does not work for cross-database updates.  To
     specify multiple rewrites, use this option multiple times.  The
     server uses the first one with a FROM_NAME value that matches. The
     database name translation is done _before_ the `--replicate-*'
     rules are tested.

     If you use this option on the command line and the ``>'' character
     is special to your command interpreter, quote the option value.
     For example:

          shell> mysqld --replicate-rewrite-db="OLDDB->NEWDB"

   *  `--replicate-same-server-id'

     To be used on slave servers. Usually you should use the default
     setting of 0, to prevent infinite loops caused by circular
     replication. If set to 1, the slave does not skip events having
     its own server ID. Normally, this is useful only in rare
     configurations. Cannot be set to 1 if `--log-slave-updates' is
     used. By default, the slave I/O thread does not write binary log
     events to the relay log if they have the slave's server ID (this
     optimization helps save disk usage). If you want to use
     `--replicate-same-server-id', be sure to start the slave with this
     option before you make the slave read its own events that you want
     the slave SQL thread to execute.

   *  `--replicate-wild-do-table=DB_NAME.TBL_NAME'

     Tells the slave thread to restrict replication to statements where
     any of the updated tables match the specified database and table
     name patterns. Patterns can contain the ``%'' and ``_'' wildcard
     characters, which have the same meaning as for the `LIKE'
     pattern-matching operator.  To specify more than one table, use
     this option multiple times, once for each table. This works for
     cross-database updates. See *Note replication-rules::.

     Example: `--replicate-wild-do-table=foo%.bar%' replicates only
     updates that use a table where the database name starts with `foo'
     and the table name starts with `bar'.

     If the table name pattern is `%', it matches any table name and
     the option also applies to database-level statements (*Note
     `CREATE DATABASE': create-database, *Note `DROP DATABASE':
     drop-database, and *Note `ALTER DATABASE': alter-database.). For
     example, if you use `--replicate-wild-do-table=foo%.%',
     database-level statements are replicated if the database name
     matches the pattern `foo%'.

     To include literal wildcard characters in the database or table
     name patterns, escape them with a backslash. For example, to
     replicate all tables of a database that is named `my_own%db', but
     not replicate tables from the `my1ownAABCdb' database, you should
     escape the ``_'' and ``%'' characters like this:
     `--replicate-wild-do-table=my\_own\%db'.  If you're using the
     option on the command line, you might need to double the
     backslashes or quote the option value, depending on your command
     interpreter. For example, with the `bash' shell, you would need to
     type `--replicate-wild-do-table=my\\_own\\%db'.

   *  `--replicate-wild-ignore-table=DB_NAME.TBL_NAME'

     Tells the slave thread not to replicate a statement where any
     table matches the given wildcard pattern. To specify more than one
     table to ignore, use this option multiple times, once for each
     table. This works for cross-database updates. See *Note
     replication-rules::.

     Example: `--replicate-wild-ignore-table=foo%.bar%' does not
     replicate updates that use a table where the database name starts
     with `foo' and the table name starts with `bar'.

     For information about how matching works, see the description of
     the `--replicate-wild-do-table' option. The rules for including
     literal wildcard characters in the option value are the same as for
     `--replicate-wild-ignore-table' as well.

   *  `--report-host=HOST_NAME'

     The host name or IP number of the slave to be reported to the
     master during slave registration. This value appears in the output
     of *Note `SHOW SLAVE HOSTS': show-slave-hosts. on the master
     server. Leave the value unset if you do not want the slave to
     register itself with the master. Note that it is not sufficient
     for the master to simply read the IP number of the slave from the
     TCP/IP socket after the slave connects. Due to NAT and other
     routing issues, that IP may not be valid for connecting to the
     slave from the master or other hosts.

   *  `--report-password=PASSWORD'

     The account password of the slave to be reported to the master
     during slave registration. This value appears in the output of
     *Note `SHOW SLAVE HOSTS': show-slave-hosts. on the master server
     if the `--show-slave-auth-info' option is given.

   *  `--report-port=SLAVE_PORT_NUM'

     The TCP/IP port number for connecting to the slave, to be reported
     to the master during slave registration. Set this only if the
     slave is listening on a non-default port or if you have a special
     tunnel from the master or other clients to the slave. If you are
     not sure, do not use this option.

   *  `--report-user=USER_NAME'

     The account user name of the slave to be reported to the master
     during slave registration. This value appears in the output of
     *Note `SHOW SLAVE HOSTS': show-slave-hosts. on the master server
     if the `--show-slave-auth-info' option is given.

   *  `--show-slave-auth-info'

     Display slave user names and passwords in the output of *Note
     `SHOW SLAVE HOSTS': show-slave-hosts. on the master server for
     slaves started with the `--report-user' and `--report-password'
     options.

   *  `--skip-slave-start'

     Tells the slave server not to start the slave threads when the
     server starts. To start the threads later, use a *Note `START
     SLAVE': start-slave. statement.

   *  `--slave_compressed_protocol={0|1}'

     If this option is set to 1, use compression for the slave/master
     protocol if both the slave and the master support it. The default
     is 0 (no compression).

   *  `--slave-load-tmpdir=FILE_NAME'

     The name of the directory where the slave creates temporary files.
     This option is by default equal to the value of the `tmpdir'
     system variable. When the slave SQL thread replicates a *Note
     `LOAD DATA INFILE': load-data. statement, it extracts the file to
     be loaded from the relay log into temporary files, and then loads
     these into the table. If the file loaded on the master is huge, the
     temporary files on the slave are huge, too. Therefore, it might be
     advisable to use this option to tell the slave to put temporary
     files in a directory located in some file system that has a lot of
     available space. In that case, the relay logs are huge as well, so
     you might also want to use the `--relay-log' option to place the
     relay logs in that file system.

     The directory specified by this option should be located in a
     disk-based file system (not a memory-based file system) because
     the temporary files used to replicate *Note `LOAD DATA INFILE':
     load-data. must survive machine restarts. The directory also
     should not be one that is cleared by the operating system during
     the system startup process.

   *  `--slave-net-timeout=SECONDS'

     The number of seconds to wait for more data from the master before
     the slave considers the connection broken, aborts the read, and
     tries to reconnect. The first retry occurs immediately after the
     timeout. The interval between retries is controlled by the
     `MASTER_CONNECT_RETRY' option for the *Note `CHANGE MASTER TO':
     change-master-to.  statement, and the number of reconnection
     attempts is limited by the `--master-retry-count' option. The
     default is 3600 seconds (one hour).

   *  `--slave-skip-errors=[ERR_CODE1,ERR_CODE2,...|all]'

     Normally, replication stops when an error occurs on the slave.
     This gives you the opportunity to resolve the inconsistency in the
     data manually. This option tells the slave SQL thread to continue
     replication when a statement returns any of the errors listed in
     the option value.

     Do not use this option unless you fully understand why you are
     getting errors. If there are no bugs in your replication setup and
     client programs, and no bugs in MySQL itself, an error that stops
     replication should never occur. Indiscriminate use of this option
     results in slaves becoming hopelessly out of synchrony with the
     master, with you having no idea why this has occurred.

     For error codes, you should use the numbers provided by the error
     message in your slave error log and in the output of *Note `SHOW
     SLAVE STATUS': show-slave-status.  *Note error-handling::, lists
     server error codes.

     You can also (but should not) use the very non-recommended value
     of `all' to cause the slave to ignore all error messages and keeps
     going regardless of what happens.  Needless to say, if you use
     `all', there are no guarantees regarding the integrity of your
     data. Please do not complain (or file bug reports) in this case if
     the slave's data is not anywhere close to what it is on the master.
     _You have been warned_.

     Examples:

          --slave-skip-errors=1062,1053
          --slave-skip-errors=all

   *  `sql_slave_skip_counter'

     *Variable Name*      `sql_slave_skip_counter'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          

     The number of events from the master that a slave server should
     skip.

     *Important*:

     If skipping the number of events specified by setting this
     variable would cause the slave to begin in the middle of an event
     group, the slave continues to skip until it finds the beginning of
     the next event group and begins from that point. See *Note
     set-global-sql-slave-skip-counter::, for more information.

   *  `--abort-slave-event-count'

     *Command Line        `--abort-slave-event-count=#'
     Format*              
     *Config File Format* `abort-slave-event-count'
     *Value Set *         
     Typenumeric          
     Default0 Min Value0  

     When this option is set to some positive integer VALUE other than
     0 (the default) it affects replication behavior as follows: After
     the slave SQL thread has started, VALUE log events are allowed to
     be executed; after that, the slave SQL thread does not receive any
     more events, just as if the network connection from the master
     were cut. The slave thread continues to run, and the output from
     *Note `SHOW SLAVE STATUS': show-slave-status. displays `Yes' in
     both the `Slave_IO_Running' and the `Slave_SQL_Running' columns,
     but no further events are read from the relay log.

     This option is used internally by the MySQL test suite for
     replication testing and debugging. It is not intended for use in a
     production setting.

   *  `--disconnect-slave-event-count'

     *Command Line        `--disconnect-slave-event-count=#'
     Format*              
     *Config File Format* `disconnect-slave-event-count'
     *Value Set *         
     Typenumeric Default0 

     This option is used internally by the MySQL test suite for
     replication testing and debugging.

Obsolete options

_The following options are removed in MySQL 6.0. If you attempt to
start *Note `mysqld': mysqld. with any of these options in MySQL 6.0,
the server aborts with an `unknown variable' error_. To set the
replication parameters formerly associated with these options, you must
use the `CHANGE MASTER TO ...' statement (see *Note change-master-to::).

The options affected are shown in this list:

   * `--master-host'

   * `--master-user'

   * `--master-password'

   * `--master-port'

   * `--master-connect-retry'

   * `--master-ssl'

   * `--master-ssl-ca'

   * `--master-ssl-capath'

   * `--master-ssl-cert'

   * `--master-ssl-cipher'

   * `--master-ssl-key'

System variables used on replication slaves

The following system variables are used for controlling replication
slave servers. Those that can be set are specified using *Note `SET':
set-option.  Server options used with replication slaves are listed
earlier in this section.

   *  `init_slave'

     *Command Line        `--init-slave=name'
     Format*              
     *Config File Format* `init_slave'
     *Option Sets         Yes, `init_slave'
     Variable*            
     *Variable Name*      `init_slave'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     This variable is similar to `init_connect', but is a string to be
     executed by a slave server each time the SQL thread starts. The
     format of the string is the same as for the `init_connect'
     variable.

     *Note*:

     The SQL thread sends an acknowledgement to the client before
     `init_slave' is executed.  Therefore, it is not guaranteed that
     `init_slave' has been executed when *Note `START SLAVE':
     start-slave.  returns. See *Note start-slave::, for more
     information.

   *  `rpl_recovery_rank'

     This variable is unused.

   *  `relay_log_recovery'

     Enables automatic relay log recovery immediately following server
     startup, which means that the replication slave discards all
     unprocessed relay logs and retrieves them from the replication
     master. This should be used following a crash on the replication
     slave to insure that no possibly corrupted relay logs are
     processed. The default value is 0 (disabled).  This global
     variable can be changed dynamically, or by starting the slave with
     the `--relay-log-recovery' option.

   *  `sync_master_info'

     *Version Introduced* 6.0.11
     *Command Line        `--sync-master-info=#'
     Format*              
     *Config File Format* `sync-master-info'
     *Variable Name*      `sync_master_info'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set (>=       
     6.0.11)*             
     Platform Bit Size64  
     Typenumeric          
     Default0             
     Range0-18446744073709547520

     If the value of this variable is greater than 0, a replication
     slave synchronizes its `master.info' file to disk (using
     `fdatasync()') after every `sync_master_info' transactions. The
     default value of `sync_relay_log_info' is 0 (recommended in most
     situations), which does not force any synchronization to disk by
     the MySQL server -- in this case, the server relies on the
     operating system to flush the `master.info' file's contents from
     time to time as for any other file.

     This variable was introduced in MySQL 6.0.11.

   *  `sync_relay_log'

     *Version Introduced* 6.0.10
     *Command Line        `--sync-relay-log=#'
     Format*              
     *Config File Format* `sync-relay-log'
     *Variable Name*      `sync_relay_log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set (>=       
     6.0.10)*             
     Platform Bit Size64  
     Typenumeric          
     Default0             
     Range0-18446744073709547520

     If the value of this variable is greater than 0, the MySQL server
     synchronizes its relay log to disk (using `fdatasync()') after
     every `sync_relay_log' writes to the relay log. There is one write
     to the relay log per statement if autocommit is enabled, and one
     write per transaction otherwise. The default value of
     `sync_relay_log' is 0, which does no synchronizing to disk -- in
     this case, the server relies on the operating system to flush the
     relay log's contents from time to time as for any other file. A
     value of 1 is the safest choice, because in the event of a crash
     you lose at most one statement or transaction from the relay log.
     However, it is also the slowest choice (unless the disk has a
     battery-backed cache, which makes synchronization very fast).

     This variable was introduced in MySQL 6.0.10.

   *  `sync_relay_log_info'

     *Version Introduced* 6.0.11
     *Command Line        `--sync-relay-log-info=#'
     Format*              
     *Config File Format* `sync-relay-log-info'
     *Variable Name*      `sync_relay_log_info'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set (>=       
     6.0.11)*             
     Platform Bit Size64  
     Typenumeric          
     Default0             
     Range0-18446744073709547520

     If the value of this variable is greater than 0, a replication
     slave synchronizes its `relay-log.info' file to disk (using
     `fdatasync()') after every `sync_relay_log_info' transactions. A
     value of 1 is the generally the best choice.  The default value of
     `sync_relay_log_info' is 0, which does not force any
     synchronization to disk by the MySQL server -- in this case, the
     server relies on the operating system to flush the
     `relay-log.info' file's contents from time to time as for any
     other file.

     This variable was introduced in MySQL 6.0.11.

   *  `slave_compressed_protocol'

     *Command Line        `--slave_compressed_protocol'
     Format*              
     *Config File Format* `slave_compressed_protocol'
     *Option Sets         Yes, `slave_compressed_protocol'
     Variable*            
     *Variable Name*      `slave_compressed_protocol'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Whether to use compression of the slave/master protocol if both
     the slave and the master support it.

   *  `slave_exec_mode'

     *Version Introduced* 6.0.5
     *Variable Name*      `slave_exec_mode'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultSTRICT Valid  
     ValuesIDEMPOTENT,    
     STRICT               

     Controls whether `IDEMPOTENT' or `STRICT' mode is used in
     replication conflict resolution and error checking. `IDEMPOTENT'
     mode causes suppression of some errors, including duplicate-key
     and no-key-found errors. Beginning with MySQL 6.0.5, this mode
     should be employed in multi-master replication, circular
     replication, and some other special replication scenarios.
     `STRICT' mode is the default, and is suitable for most other cases.

   *  `slave_load_tmpdir'

     *Command Line        `--slave-load-tmpdir=name'
     Format*              
     *Config File Format* `slave-load-tmpdir'
     *Option Sets         Yes, `slave_load_tmpdir'
     Variable*            
     *Variable Name*      `slave_load_tmpdir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     Default/tmp          

     The name of the directory where the slave creates temporary files
     for replicating *Note `LOAD DATA INFILE': load-data. statements.

   *  `slave_net_timeout'

     *Command Line        `--slave-net-timeout=#'
     Format*              
     *Config File Format* `slave-net-timeout'
     *Option Sets         Yes, `slave_net_timeout'
     Variable*            
     *Variable Name*      `slave_net_timeout'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default3600 Min      
     Value1               

     The number of seconds to wait for more data from a master/slave
     connection before aborting the read. This timeout applies only to
     TCP/IP connections, not to connections made via Unix socket files,
     named pipes, or shared memory.

   *  `slave_skip_errors'

     *Command Line        `--slave-skip-errors=name'
     Format*              
     *Config File Format* `slave-skip-errors'
     *Option Sets         Yes, `slave_skip_errors'
     Variable*            
     *Variable Name*      `slave_skip_errors'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     Normally, replication stops when an error occurs on the slave.
     This gives you the opportunity to resolve the inconsistency in the
     data manually. This variable tells the slave SQL thread to
     continue replication when a statement returns any of the errors
     listed in the variable value.

   *  `slave_transaction_retries'

     *Command Line        `--slave_transaction_retries=#'
     Format*              
     *Config File Format* `slave_transaction_retries'
     *Option Sets         Yes, `slave_transaction_retries'
     Variable*            
     *Variable Name*      `slave_transaction_retries'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default10            
     Range0-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default10            
     Range0-18446744073709547520

     If a replication slave SQL thread fails to execute a transaction
     because of an `InnoDB' deadlock or because the transaction's
     execution time exceeded `InnoDB''s `innodb_lock_wait_timeout', it
     automatically retries `slave_transaction_retries'
     (http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_transaction_retries)
     times before stopping with an error. The default value is 10.


File: manual.info,  Node: replication-options-binary-log,  Prev: replication-options-slave,  Up: replication-options

16.1.3.4 Binary Log Options and Variables
.........................................

You can use the *Note `mysqld': mysqld. options and system variables
that are described in this section to affect the operation of the
binary log as well as to control which statements are written to the
binary log. For additional information about the binary log, see *Note
binary-log::. For additional information about using MySQL server
options and system variables, see *Note server-options::, and *Note
server-system-variables::.

Startup options used with binary logging

The following list describes startup options for for enabling and
configuring the binary log. Many of these options can be reset while
the server is running by using the *Note `CHANGE MASTER TO':
change-master-to. statement.  Others, can be set only when the slave
server starts. System variables used with binary logging are discussed
later in this section.

   *  `--binlog-row-event-max-size=N'

     *Command Line        `--binlog-row-event-max-size=#'
     Format*              
     *Config File Format* `binlog-row-event-max-size'
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default1024          
     Range256-4294967295  
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default1024          
     Range256-18446744073709547520

     Specify the maximum size of a row-based binary log event, in
     bytes. Rows are grouped into events smaller than this size if
     possible. The value should be a multiple of 256. The default is
     1024. See *Note replication-formats::.

   *  `--log-bin[=BASE_NAME]'

     *Command Line        `--log-bin'
     Format*              
     *Config File Format* `log-bin'
     *Variable Name*      `log_bin'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     DefaultOFF           

     Enable binary logging. The server logs all statements that change
     data to the binary log, which is used for backup and replication.
     See *Note binary-log::.

     The option value, if given, is the basename for the log sequence.
     The server creates binary log files in sequence by adding a
     numeric suffix to the basename. It is recommended that you specify
     a basename (see Additional Known Issues
     (http://dev.mysql.com/doc/refman/5.1/en/bugs.html#open-bugs-general),
     for the reason).  Otherwise, MySQL uses `HOST_NAME-bin' as the
     basename.

   *  `--log-bin-index[=FILE_NAME]'

     *Command Line        `--log-bin-index=name'
     Format*              
     *Config File Format* `log-bin-index'
     *Value Set *         
     Typefilename         
     DefaultOFF           

     The index file for binary log file names. See *Note binary-log::.
     If you omit the file name, and if you didn't specify one with
     `--log-bin', MySQL uses `HOST_NAME-bin.index' as the file name.

   * Statement selection options

     The options in the following list affect which statements are
     written to the binary log, and thus sent by a replication master
     server to its slaves.

        *  `--binlog-do-db=DB_NAME'

          This option affects binary logging in the same manner that
          `--replicate-do-db' affects replication.

          The effects of this option depend on whether the
          statement-based or row-based logging format is in use, in the
          same way that the effects of `--replicate-do-db' depend on
          whether statement-based or row-based replication is in use.

          Statement-based logging

          Only those statements where the default database (that is,
          the one selected by *Note `USE': use.) is DB_NAME are written
          to the binary log. To specify more than one database, use this
          option multiple times, once for each database; however, doing
          so does _not_ cause cross-database statements such as `UPDATE
          SOME_DB.SOME_TABLE SET foo='bar'' to be logged while a
          different database (or no database) is selected.

          *Warning*:

          To specify multiple databases you _must_ use multiple
          instances of this option. Because database names can contain
          commas, if you supply a comma separated list then the list
          will be treated as the name of a single database.

          An example of what does not work as you might expect when
          using statement-based logging: If the server is started with
          `--binlog-do-db=sales' and you issue the following
          statements, the *Note `UPDATE': update. statement is _not_
          logged:

               USE prices;
               UPDATE sales.january SET amount=amount+1000;

          The main reason for this `just check the default database'
          behavior is that it is difficult from the statement alone to
          know whether it should be replicated (for example, if you are
          using multiple-table *Note `DELETE': delete. statements or
          multiple-table *Note `UPDATE': update.  statements that act
          across multiple databases). It is also faster to check only
          the default database rather than all databases if there is no
          need.

          Row-based logging

          Logging is restricted to database DB_NAME. Only changes to
          tables belonging to DB_NAME are logged; the current database
          has no effect on this.  For example, suppose that the server
          is started with `--replicate-do-db=sales' and row-based
          logging is in effect, and then the following statements are
          executed:

               USE prices;
               UPDATE sales.february SET amount=amount+100;

          The `february' table in the `sales' database is changed in
          accordance with the *Note `UPDATE': update. statement; this
          occurs whether or not the *Note `USE': use. statement was
          issued.  However, the following statements are not logged when
          using the row-based logging format and `--binlog-do-db=sales':

               USE prices;
               UPDATE prices.march SET amount=amount-25;

          Even if the statement `USE prices' were changed to `USE
          sales', the *Note `UPDATE': update. statement's effects would
          still not be written to the binary log.

          Another important difference in how `--binlog-do-db' is
          handled when using the statement-based logging format as
          opposed to the row-based format occurs with regard to
          statements that refer to multiple databases. Suppose the
          server is started with `--binlog-do-db=db1', and the
          following statements are executed:

               USE db1;
               UPDATE db1.table1 SET col1 = 10, db2.table2 SET col2 = 20;

          If you are using statement-based logging, then the updates to
          both tables are written to the binary log. However, when
          using the row-based format, only the changes to `table1'
          logged; since `table2' is in a different database, it is not
          changed by the *Note `UPDATE': update. Now suppose that,
          instead of the `USE db1' statement, a `USE db4' statement had
          been used:

               USE db4;
               UPDATE db1.table1 SET col1 = 10, db2.table2 SET col2 = 20;

          In this case, the *Note `UPDATE': update.  statement would
          not be written to the binary log when using statement-based
          logging. However, if using row-based logging, the *Note
          `UPDATE': update. would change `table1', but not `table2' --
          in other words, only tables in the database named by
          `--binlog-do-db' are changed, and the choice of current
          database has no effect on this behavior.

        *  `--binlog-ignore-db=DB_NAME'

          This option affects binary logging in the same manner that
          `--replicate-ignore-db' affects replication.

          The effects of this option depend on whether the
          statement-based or row-based logging format is in use, in the
          same way that the effects of `--replicate-ignore-db' depend
          on whether statement-based or row-based replication is in use.

          Statement-based logging

          Tells the server to not log any statement where the default
          database (that is, the one selected by *Note `USE': use.) is
          DB_NAME.

          Row-based format

          Tells the server not to log updates to any tables in the
          database DB_NAME. The current database has no effect.

          When using statement-based logging, the following example
          does not work as you might expect. Suppose that the server is
          started with `--binlog-ignore-db=sales' and you issue the
          following statements:

               USE prices;
               UPDATE sales.january SET amount=amount+1000;

          The *Note `UPDATE': update. statement _is_ logged in such a
          case because `--binlog-ignore-db' applies only to the default
          database (determined by the *Note `USE': use. statement).
          Because the `sales' database was specified explicitly in the
          statement, the statement has not been filtered.  However,
          when using row-based logging, the *Note `UPDATE': update.
          statement's effects are _not_ written to the binary log,
          which means that no changes to the `sales.january' table are
          logged; in this instance, `--binlog-ignore-db=sales' causes
          _all_ changes made to tables in the master's copy of the
          `sales' database to be ignored for purposes of binary logging.

          To specify more than one database to ignore, use this option
          multiple times, once for each database. Because database
          names can contain commas, if you supply a comma separated
          list then the list will be treated as the name of a single
          database.

          You should not use this option if you are using
          cross-database updates and you do not want these updates to
          be logged.

     Additional server options that can be used to control logging also
     affect the binary log. For more information about these, see *Note
     server-options::. For more information about how the options in
     the previous list are applied, see *Note binary-log::.

     There are also options for slave servers that control which
     statements received from the master should be executed or ignored.
     For details, see *Note replication-options-slave::.

   *  `--log-bin-trust-function-creators[={0|1}]'

     *Command Line        `--log-bin-trust-function-creators'
     Format*              
     *Config File Format* `log-bin-trust-function-creators'
     *Option Sets         Yes, `log_bin_trust_function_creators'
     Variable*            
     *Variable Name*      `log_bin_trust_function_creators'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     With no argument or an argument of 1, this option sets the
     `log_bin_trust_function_creators' system variable to 1. With an
     argument of 0, this option sets the system variable to 0.
     `log_bin_trust_function_creators' affects how MySQL enforces
     restrictions on stored function and trigger creation. See *Note
     stored-programs-logging::.

Testing and debugging options

The following binary log options are used in replication testing and
debugging. They are not intended for use in normal operations.

   *  `--max-binlog-dump-events'

     *Command Line        `--max-binlog-dump-events=#'
     Format*              
     *Config File Format* `max-binlog-dump-events'
     *Value Set *         
     Typenumeric Default0 

     This option is used internally by the MySQL test suite for
     replication testing and debugging.

   *  `--sporadic-binlog-dump-fail'

     *Command Line        `--sporadic-binlog-dump-fail'
     Format*              
     *Config File Format* `sporadic-binlog-dump-fail'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     This option is used internally by the MySQL test suite for
     replication testing and debugging.

System variables used with the binary log

The following system variables are used for controlling replication
slave servers. Those that can be set are specified using *Note `SET':
set-option.  Server options used with replication slaves are listed
earlier in this section.

   *  `binlog_cache_size'

     *Command Line        `--binlog_cache_size=#'
     Format*              
     *Config File Format* `binlog_cache_size'
     *Option Sets         Yes, `binlog_cache_size'
     Variable*            
     *Variable Name*      `binlog_cache_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default32768         
     Range4096-4294967295 
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default32768         
     Range4096-18446744073709547520

     The size of the cache to hold the SQL statements for the binary
     log during a transaction. A binary log cache is allocated for each
     client if the server supports any transactional storage engines
     and if the server has the binary log enabled (`--log-bin' option).
     If you often use large, multiple-statement transactions, you can
     increase this cache size to get more performance. The
     `Binlog_cache_use' and `Binlog_cache_disk_use' status variables
     can be useful for tuning the size of this variable.  See *Note
     binary-log::.

     MySQL Enterprise

     For recommendations on the optimum setting for `binlog_cache_size'
     subscribe to the MySQL Enterprise Monitor. For more information,
     see `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `binlog_format'

     *Command Line        `--binlog-format'
     Format*              
     *Config File Format* `binlog-format'
     *Option Sets         Yes, `binlog_format'
     Variable*            
     *Variable Name*      `binlog_format'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultSTATEMENT     
     Valid ValuesROW,     
     STATEMENT, MIXED     

     This variable sets the binary logging format, and can be any one
     of `STATEMENT', `ROW', or `MIXED'.  `binlog_format' is set by the
     `--binlog-format' option at startup, or by the `binlog_format'
     variable at runtime.

     You must have the `SUPER' privilege to set this variable, which
     (unlike with most system variables) is true as of MySQL 6.0.8 even
     for the session value. See *Note replication-formats::.

     The rules governing when changing this variable takes effect and
     how long the effect lasts are the same as for other MySQL server
     system variables. See *Note set-option::, for more information.

     `MIXED' is used by default before MySQL 6.0.8; `STATEMENT' is the
     default beginning with MySQL 6.0.8.

     If `MIXED' is specified, statement-based replication is used
     except for cases where only row-based replication is guaranteed to
     lead to proper results. For example, this happens when statements
     contain user-defined functions (UDF) or the `UUID()' function. An
     exception to this rule is that `MIXED' always uses statement-based
     replication for stored functions and triggers.

     There are exceptions when you cannot switch the replication format
     at runtime:

        * From within a stored function or a trigger.

        * If the session is currently in row-based replication mode and
          has open temporary tables.

     Trying to switch the format in those cases results in an error.

     The binlog format affects the behavior of the following server
     options:

        * `--replicate-do-db'

        * `--replicate-ignore-db'

        * `--binlog-do-db'

        * `--binlog-ignore-db'

     These effects are discussed in detail in the descriptions of the
     individual options.

   *  `max_binlog_cache_size'

     *Command Line        `--max_binlog_cache_size=#'
     Format*              
     *Config File Format* `max_binlog_cache_size'
     *Option Sets         Yes, `max_binlog_cache_size'
     Variable*            
     *Variable Name*      `max_binlog_cache_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default4294967295    
     Range4096-4294967295 
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default18446744073709547520
     Range4096-18446744073709547520

     If a multiple-statement transaction requires more than this many
     bytes of memory, the server generates a `Multi-statement
     transaction required more than 'max_binlog_cache_size' bytes of
     storage' error.  The minimum value is 4096; the maximum and
     default values are 4GB on 32-bit platforms and 16 PB (petabytes)
     on 64-bit platforms.

   *  `max_binlog_size'

     *Command Line        `--max_binlog_size=#'
     Format*              
     *Config File Format* `max_binlog_size'
     *Option Sets         Yes, `max_binlog_size'
     Variable*            
     *Variable Name*      `max_binlog_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1073741824    
     Min Value4096        

     If a write to the binary log causes the current log file size to
     exceed the value of this variable, the server rotates the binary
     logs (closes the current file and opens the next one).  You cannot
     set this variable to more than 1GB or to less than 4096 bytes. The
     default value is 1GB.

     A transaction is written in one chunk to the binary log, so it is
     never split between several binary logs. Therefore, if you have
     big transactions, you might see binary logs larger than
     `max_binlog_size'.

     If `max_relay_log_size' is 0, the value of `max_binlog_size'
     applies to relay logs as well.

   *  `sync_binlog'

     *Command Line        `--sync-binlog=#'
     Format*              
     *Config File Format* `sync-binlog'
     *Option Sets         Yes, `sync_binlog'
     Variable*            
     *Variable Name*      `sync_binlog'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Platform Bit Size32  
     Typenumeric          
     Default0             
     Range0-4294967295    
     *Value Set *         
     Platform Bit Size64  
     Typenumeric          
     Default0             
     Range0-18446744073709547520

     If the value of this variable is greater than 0, the MySQL server
     synchronizes its binary log to disk (using `fdatasync()') after
     every `sync_binlog' writes to the binary log. There is one write
     to the binary log per statement if autocommit is enabled, and one
     write per transaction otherwise. The default value of
     `sync_binlog' is 0, which does no synchronizing to disk -- in this
     case, the server relies on the operating system to flush the
     binary log's contents from to time as for any other file. A value
     of 1 is the safest choice, because in the event of a crash you
     lose at most one statement or transaction from the binary log.
     However, it is also the slowest choice (unless the disk has a
     battery-backed cache, which makes synchronization very fast).


File: manual.info,  Node: replication-administration,  Prev: replication-options,  Up: replication-configuration

16.1.4 Common Replication Administration Tasks
----------------------------------------------

* Menu:

* replication-administration-status::  Checking Replication Status
* replication-administration-pausing::  Pausing Replication on the Slave

Once replication has been started it should execute without requiring
much regular administration. Depending on your replication environment,
you will want to check the replication status of each slave either
periodically, daily, or even more frequently.

MySQL Enterprise

For regular reports regarding the status of your slaves, subscribe to
the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: replication-administration-status,  Next: replication-administration-pausing,  Prev: replication-administration,  Up: replication-administration

16.1.4.1 Checking Replication Status
....................................

The most common task when managing a replication process is to ensure
that replication is taking place and that there have been no errors
between the slave and the master.

The primary statement for this is *Note `SHOW SLAVE STATUS':
show-slave-status. which you must execute on each slave:

     mysql> SHOW SLAVE STATUS\G
     *************************** 1. row ***************************
                  Slave_IO_State: Waiting for master to send event
                     Master_Host: master1
                     Master_User: root
                     Master_Port: 3306
                   Connect_Retry: 60
                 Master_Log_File: mysql-bin.000004
             Read_Master_Log_Pos: 931
                  Relay_Log_File: slave1-relay-bin.000056
                   Relay_Log_Pos: 950
           Relay_Master_Log_File: mysql-bin.000004
                Slave_IO_Running: Yes
               Slave_SQL_Running: Yes
                 Replicate_Do_DB:
             Replicate_Ignore_DB:
              Replicate_Do_Table:
          Replicate_Ignore_Table:
         Replicate_Wild_Do_Table:
     Replicate_Wild_Ignore_Table:
                      Last_Errno: 0
                      Last_Error:
                    Skip_Counter: 0
             Exec_Master_Log_Pos: 931
                 Relay_Log_Space: 1365
                 Until_Condition: None
                  Until_Log_File:
                   Until_Log_Pos: 0
              Master_SSL_Allowed: No
              Master_SSL_CA_File:
              Master_SSL_CA_Path:
                 Master_SSL_Cert:
               Master_SSL_Cipher:
                  Master_SSL_Key:
           Seconds_Behind_Master: 0
     1 row in set (0.01 sec)

The key fields from the status report to examine are:

   * `Slave_IO_State' -- indicates the current status of the slave. See
     *Note slave-io-thread-states::, and *Note
     slave-sql-thread-states::, for more information.

   * `Slave_IO_Running' -- shows whether the IO thread for the reading
     the master's binary log is running.

   * `Slave_SQL_Running' -- shows whether the SQL thread for the
     executing events in the relay log is running.

   * `Last_Error' -- shows the last error registered when processing
     the relay log. Ideally this should be blank, indicating no errors.

   * `Seconds_Behind_Master' -- shows the number of seconds that the
     slave SQL thread is behind processing the master binary log. A
     high number (or an increasing one) can indicate that the slave is
     unable to cope with the large number of statements from the master.

     A value of 0 for `Seconds_Behind_Master' can usually be
     interpreted as meaning that the slave has caught up with the
     master, but there are some cases where this is not strictly true.
     For example, this can occur if the network connection between
     master and slave is broken but the slave I/O thread has not yet
     noticed this -- that is, `slave_net_timeout'
     (http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_net_timeout)
     has not yet elapsed.

     It is also possible that transient values for
     `Seconds_Behind_Master' may not reflect the situation accurately.
     When the slave SQL thread has caught up on I/O,
     `Seconds_Behind_Master' displays 0; but when the slave I/O thread
     is still queuing up a new event, `Seconds_Behind_Master' may show a
     large value until the SQL thread finishes executing the new event.
     This is especially likely when the events have old timestamps; in
     such cases, if you execute *Note `SHOW SLAVE STATUS':
     show-slave-status. several times in a relatively short peiod, you
     may see this value change back and forth repeatedly between 0 and
     a relatively large value.

On the master, you can check the status of slaves by examining the list
of running processes. Slaves execute the `Binlog Dump' command:

     mysql> SHOW PROCESSLIST \G;
     *************************** 4. row ***************************
          Id: 10
        User: root
        Host: slave1:58371
          db: NULL
     Command: Binlog Dump
        Time: 777
       State: Has sent all binlog to slave; waiting for binlog to be updated
        Info: NULL

Because it is the slave that drives the core of the replication
process, very little information is available in this report.

If you have used the `--report-host' option, then the *Note `SHOW SLAVE
HOSTS': show-slave-hosts.  statement will show basic information about
connected slaves:

     mysql> SHOW SLAVE HOSTS;
     +-----------+--------+------+-------------------+-----------+
     | Server_id | Host   | Port | Rpl_recovery_rank | Master_id |
     +-----------+--------+------+-------------------+-----------+
     |        10 | slave1 | 3306 |                 0 |         1 |
     +-----------+--------+------+-------------------+-----------+
     1 row in set (0.00 sec)

The output includes the ID of the slave server, the value of the
`--report-host' option, the connecting port, master ID and the priority
of the slave for receiving binary log updates.


File: manual.info,  Node: replication-administration-pausing,  Prev: replication-administration-status,  Up: replication-administration

16.1.4.2 Pausing Replication on the Slave
.........................................

You can stop and start the replication of statements on the slave using
the *Note `STOP SLAVE': stop-slave. and *Note `START SLAVE':
start-slave. statements.

To stop execution of the binary log from the master, use *Note `STOP
SLAVE': stop-slave.:

     mysql> STOP SLAVE;

When execution is stopped, the slave does not read the binary log from
the master (the `IO_THREAD') and stops processing events from the relay
log that have not yet been executed (the `SQL_THREAD'). You can pause
either the IO or SQL threads individually by specifying the thread
type. For example:

     mysql> STOP SLAVE IO_THREAD;

Stopping the SQL thread can be useful if you want to perform a backup
or other task on a slave that only processes events from the master.
The IO thread will continue to be read from the master, but not
executed, which will make it easier for the slave to catch up when you
start slave operations again.

Stopping the IO thread will allow the statements in the relay log to be
executed up until the point where the relay log has ceased to receive
new events. Using this option can be useful when you want to pause
execution to allow the slave to catch up with events from the master,
when you want to perform administration on the slave but also ensure
you have the latest updates to a specific point. This method can also
be used to pause execution on the slave while you conduct
administration on the master while ensuring that there is not a massive
backlog of events to be executed when replication is started again.

To start execution again, use the *Note `START SLAVE': start-slave.
statement:

     mysql> START SLAVE;

If necessary, you can start either the `IO_THREAD' or `SQL_THREAD'
threads individually.


File: manual.info,  Node: replication-solutions,  Next: replication-notes,  Prev: replication-configuration,  Up: replication

16.2 Replication Solutions
==========================

* Menu:

* replication-solutions-backups::  Using Replication for Backups
* replication-solutions-diffengines::  Using Replication with Different Master and Slave Storage Engines
* replication-solutions-scaleout::  Using Replication for Scale-Out
* replication-solutions-partitioning::  Replicating Different Databases to Different Slaves
* replication-solutions-performance::  Improving Replication Performance
* replication-solutions-switch::  Switching Masters During Failover
* replication-solutions-multi-master-upgrade::  Upgrading Multi-Master Replication
* replication-solutions-ssl::    Setting Up Replication Using SSL
* replication-semisync::         Semisynchronous Replication

Replication can be used in many different environments for a range of
purposes. In this section you will find general notes and advice on
using replication for specific solution types.

For information on using replication in a backup environment, including
notes on the setup, backup procedure, and files to back up, see *Note
replication-solutions-backups::.

For advice and tips on using different storage engines on the master
and slaves, see *Note replication-solutions-diffengines::.

Using replication as a scale-out solution requires some changes in the
logic and operation of applications that use the solution. See *Note
replication-solutions-scaleout::.

For performance or data distribution reasons you may want to replicate
different databases to different replication slaves. See *Note
replication-solutions-partitioning::

As the number of replication slaves increases, the load on the master
can increase (because of the need to replicate the binary log to each
slave) and lead to a reduction in performance of the master.  For tips
on improving your replication performance, including using a single
secondary server as an replication master, see *Note
replication-solutions-performance::.

For guidance on switching masters, or converting slaves into masters as
part of an emergency failover solution, see *Note
replication-solutions-switch::.

To secure your replication communication you can encrypt the
communication channel by using SSL to exchange data. Step-by-step
instructions can be found in *Note replication-solutions-ssl::.


File: manual.info,  Node: replication-solutions-backups,  Next: replication-solutions-diffengines,  Prev: replication-solutions,  Up: replication-solutions

16.2.1 Using Replication for Backups
------------------------------------

* Menu:

* replication-solutions-backups-mysqldump::  Backing Up a Slave Using `mysqldump'
* replication-solutions-backups-rawdata::  Backing Up Raw Data from a Slave
* replication-solutions-backups-read-only::  Backing Up a Master or Slave by Making It Read Only

You can use replication as a backup solution by replicating data from
the master to a slave, and then backing up the data slave.  Because the
slave can be paused and shut down without affecting the running
operation of the master you can produce an effective snapshot of 'live'
data that would otherwise require a shutdown of the master database.

How you back up the database will depend on the size of the database
and whether you are backing up only the data, or the data and the
replication slave state so that you can rebuild the slave in the event
of failure. There are therefore two choices:

If you are using replication as a solution to enable you to back up the
data on the master, and the size of your database is not too large,
then the *Note `mysqldump': mysqldump. tool may be suitable. See *Note
replication-solutions-backups-mysqldump::.

For larger databases, where *Note `mysqldump': mysqldump. would be
impractical or inefficient, you can back up the raw data files instead.
Using the raw data files option also means that you can back up the
binary and relay logs that will enable you to recreate the slave in the
event of a slave failure. For more information, see *Note
replication-solutions-backups-rawdata::.

Another backup strategy, which can be used for either master or slave
servers, is to put the server in a read-only state. The backup is
performed against the read-only server, which then is changed back to
its usual read/write operational status. See *Note
replication-solutions-backups-read-only::.


File: manual.info,  Node: replication-solutions-backups-mysqldump,  Next: replication-solutions-backups-rawdata,  Prev: replication-solutions-backups,  Up: replication-solutions-backups

16.2.1.1 Backing Up a Slave Using `mysqldump'
.............................................

Using *Note `mysqldump': mysqldump. to create a copy of the database
enables you to capture all of the data in the database in a format that
allows the information to be imported into another instance of MySQL.
Because the format of the information is SQL statements the file can
easily be distributed and applied to running servers in the event that
you need access to the data in an emergency. However, if the size of
your data set is very large then *Note `mysqldump': mysqldump. may be
impractical.

When using *Note `mysqldump': mysqldump. you should stop the slave
before starting the dump process to ensure that the dump contains a
consistent set of data:

  1. Stop the slave from processing requests. You can either stop the
     slave completely using *Note `mysqladmin': mysqladmin.:

          shell> mysqladmin stop-slave

     Alternatively, you can stop processing the relay log files by
     stopping the replication SQL thread. Using this method will allow
     the binary log data to be transferred. Within busy replication
     environments this may speed up the catch-up process when you start
     the slave processing again:

          shell> mysql -e 'STOP SLAVE SQL_THREAD;'

  2. Run *Note `mysqldump': mysqldump. to dump your databases. You may
     either select databases to be dumped, or dump all databases. For
     more information, see *Note mysqldump::. For example, to dump all
     databases:

          shell> mysqldump --all-databases >fulldb.dump

  3. Once the dump has completed, start slave operations again:

          shell> mysqladmin start-slave

In the preceding example you may want to add login credentials (user
name, password) to the commands, and bundle the process up into a
script that you can run automatically each day.

If you use this approach, make sure you monitor the slave replication
process to ensure that the time taken to run the backup in this way is
not affecting the slave's ability to keep up with events from the
master. See *Note replication-administration-status::. If the slave is
unable to keep up you may want to add another server and distribute the
backup process. For an example of how to configure this scenario, see
*Note replication-solutions-partitioning::.


File: manual.info,  Node: replication-solutions-backups-rawdata,  Next: replication-solutions-backups-read-only,  Prev: replication-solutions-backups-mysqldump,  Up: replication-solutions-backups

16.2.1.2 Backing Up Raw Data from a Slave
.........................................

To guarantee the integrity of the files that are copied, backing up the
raw data files on your MySQL replication slave should take place while
your slave server is shut down. If the MySQL server is still running
then background tasks, particularly with storage engines with
background processes such as InnoDB, may still be updating the database
files. With InnoDB, these problems should be resolved during crash
recovery, but since the slave server can be shut down during the backup
process without affecting the execution of the master it makes sense to
take advantage of this facility.

To shut down the server and back up the files:

  1. Shut down the slave MySQL server:

          shell> mysqladmin shutdown

  2. Copy the data files. You can use any suitable copying or archive
     utility, including `cp', `tar' or `WinZip':

          shell> tar cf /tmp/dbbackup.tar ./data

  3. Start up the *Note `mysqld': mysqld. process again:

          shell> mysqld_safe &

     Under Windows:

          C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqld"

Normally you should back up the entire data folder for the slave MySQL
server. If you want to be able to restore the data and operate as a
slave (for example, in the event of failure of the slave), then when
you back up the slave's data, you should back up the slave status
files, `master.info' and `relay-log.info', along with the relay log
files. These files are needed to resume replication after you restore
the slave's data.

If you lose the relay logs but still have the `relay-log.info' file,
you can check it to determine how far the SQL thread has executed in
the master binary logs. Then you can use *Note `CHANGE MASTER TO':
change-master-to. with the `MASTER_LOG_FILE' and `MASTER_LOG_POS'
options to tell the slave to re-read the binary logs from that point.
Of course, this requires that the binary logs still exist on the master
server.

If your slave is subject to replicating *Note `LOAD DATA INFILE':
load-data. statements, you should also back up any `SQL_LOAD-*' files
that exist in the directory that the slave uses for this purpose. The
slave needs these files to resume replication of any interrupted *Note
`LOAD DATA INFILE': load-data. operations. The directory location is
specified using the `--slave-load-tmpdir' option. If this option is not
specified, the directory location is the value of the `tmpdir' system
variable.


File: manual.info,  Node: replication-solutions-backups-read-only,  Prev: replication-solutions-backups-rawdata,  Up: replication-solutions-backups

16.2.1.3 Backing Up a Master or Slave by Making It Read Only
............................................................

It is possible to back up either master or slave servers in a
replication setup by acquiring a global read lock and manipulating the
`read_only' system variable to change the read-only state of the server
to be backed up:

  1. Make the server read-only, so that it processes only retrievals
     and blocks updates

  2. Perform the backup

  3. Change the server back to its normal read/write state

The following instructions describe how to do this for a master server
and for a slave server.

*Note*:

The instructions in this section place the server to be backed up in a
state that is safe for backup methods that get the data from the
server, such as *Note `mysqldump': mysqldump.  (see *Note mysqldump::).
You should not attempt to use these instructions to make a binary
backup by copying files directly because the server may still have
modified data cached in memory and not flushed to disk.

For both scenarios discussed here, suppose that you have the following
replication setup:

   * A master server M1

   * A slave server S1 that has M1 as its master

   * A client C1 connected to M1

   * A client C2 connected to S1

*Scenario 1: Backup with a Read-Only Master*

Put the master M1 in a read-only state by executing these statements on
it:

     FLUSH TABLES WITH READ LOCK;
     SET GLOBAL read_only = ON;

While M1 is in a read-only state, the following properties are true:

   * Requests for updates sent by C1 to M1 will fail because the server
     is in read-only mode

   * Requests for retrievals sent by C1 to M1 will succeed

   * Making a backup on M1 is safe

   * Making a backup on S1 is not safe: this server is still running,
     and might be processing the binary log or update requests coming
     from client C2 (S1 might not be in a read-only state)

While M1 is read only, perform the backup. For example, you can use
*Note `mysqldump': mysqldump.

After the backup on M1 has been done, restore M1 to its normal
operational state by executing these statements:

     SET GLOBAL read_only = OFF;
     UNLOCK TABLES;

Although performing the backup on M1 is safe (as far as the backup is
concerned), it is not optimal because clients of M1 are blocked from
executing updates.

This strategy also applies to backing up a single server in a
non-replication setting.

*Scenario 2: Backup with a Read-Only Slave*

Put the slave S1 in a read-only state by executing these statements on
it:

     FLUSH TABLES WITH READ LOCK;
     SET GLOBAL read_only = ON;

While S1 is in a read-only state, the following properties are true:

   * The master M1 will continue to operate

   * Making a backup on the master is not safe

   * The slave S1 is stopped

   * Making a backup on the slave S1 is safe

These properties provide the basis for a popular backup scenario:
Having one slave busy performing a backup for a while is not a problem
because it does not affect the entire network, and the system is still
running during the backup. (For example, clients can still perform
updates on the master server.)

While S1 is read only, perform the backup.

After the backup on S1 has been done, restore S1 to its normal
operational state by executing these statements:

     SET GLOBAL read_only = OFF;
     UNLOCK TABLES;

After the slave is restored to normal operation, it again synchronizes
to the master by catching up with any outstanding updates in the binary
log from the master.

In either scenario, the statements to acquire the global read lock and
manipulate the `read_only' variable are performed on the server to be
backed up and do not propagate to any slaves of that server.


File: manual.info,  Node: replication-solutions-diffengines,  Next: replication-solutions-scaleout,  Prev: replication-solutions-backups,  Up: replication-solutions

16.2.2 Using Replication with Different Master and Slave Storage Engines
------------------------------------------------------------------------

The replication process does not care if the source table on the master
and the replicated table on the slave use different engine types. In
fact, the system variable `storage_engine' is not replicated.

This provides a number of advantages in the replication process in that
you can take advantage of different engine types for different
replication scenarios. For example, in a typical scaleout scenario (see
*Note replication-solutions-scaleout::), you want to use `InnoDB'
tables on the master to take advantage of the transactional
functionality, but use `MyISAM' on the slaves where transaction support
is not required because the data is only read. When using replication
in a data logging environment you may want to use the `Archive' storage
engine on the slave.

Setting up different engines on the master and slave depends on how you
set up the initial replication process:

   * If you used *Note `mysqldump': mysqldump. to create the database
     snapshot on your master then you could edit the dump text to
     change the engine type used on each table.

     Another alternative for *Note `mysqldump': mysqldump. is to
     disable engine types that you do not want to use on the slave
     before using the dump to build the data on the slave. For example,
     you can add the `--skip-innodb' option on your slave to disable
     the `InnoDB' engine. If a specific engine does not exist, MySQL
     will use the default engine type, usually `MyISAM'. If you want to
     disable further engines in this way, you may want to consider
     building a special binary to be used on the slave that only
     supports the engines you want.

   * If you are using raw data files for the population of the slave,
     you will be unable to change the initial table format.  Instead,
     use *Note `ALTER TABLE': alter-table. to change the table types
     after the slave has been started.

   * For new master/slave replication setups where there are currently
     no tables on the master, avoid specifying the engine type when
     creating new tables.

If you are already running a replication solution and want to convert
your existing tables to another engine type, follow these steps:

  1. Stop the slave from running replication updates:

          mysql> STOP SLAVE;

     This will enable you to change engine types without interruptions.

  2. Execute an `ALTER TABLE ...  Engine='ENGINETYPE'' for each table
     where you want to change the engine type.

  3. Start the slave replication process again:

          mysql> START SLAVE;

Although the `storage_engine' variable is not replicated, be aware that
*Note `CREATE TABLE': create-table. and *Note `ALTER TABLE':
alter-table. statements that include the engine specification will be
correctly replicated to the slave. For example, if you have a CSV table
and you execute:

     mysql> ALTER TABLE csvtable Engine='MyISAM';

The above statement will be replicated to the slave and the engine type
on the slave will be converted to `MyISAM', even if you have previously
changed the table type on the slave to an engine other than CSV. If you
want to retain engine differences on the master and slave, you should
be careful to use the `storage_engine' variable on the master when
creating a new table. For example, instead of:

     mysql> CREATE TABLE tablea (columna int) Engine=MyISAM;

Use this format:

     mysql> SET storage_engine=MyISAM;
     mysql> CREATE TABLE tablea (columna int);

When replicated, the `storage_engine' variable will be ignored, and the
*Note `CREATE TABLE': create-table.  statement will be executed with
the slave's default engine type.


File: manual.info,  Node: replication-solutions-scaleout,  Next: replication-solutions-partitioning,  Prev: replication-solutions-diffengines,  Up: replication-solutions

16.2.3 Using Replication for Scale-Out
--------------------------------------

You can use replication as a scale-out solution, i.e. where you want to
split up the load of database queries across multiple database servers,
within some reasonable limitations.

Because replication works from the distribution of one master to one or
more slaves, using replication for scaleout works best in an
environment where you have a high number of reads and low number of
writes/updates. Most websites fit into this category, where users are
browsing the website, reading articles, posts, or viewing products.
Updates only occur during session management, or when making a purchase
or adding a comment/message to a forum.

Replication in this situation enables you to distribute the reads over
the replication slaves, while still allowing your web servers to
communicate with the replication master when a write is required. You
can see a sample replication layout for this scenario in *Note
figure_replication-scaleout::.

FIGURE GOES HERE: Using replication to improve the performance during
scaleout

If the part of your code that is responsible for database access has
been properly abstracted/modularized, converting it to run with a
replicated setup should be very smooth and easy. Change the
implementation of your database access to send all writes to the
master, and to send reads to either the master or a slave. If your code
does not have this level of abstraction, setting up a replicated system
gives you the opportunity and motivation to clean it up. Start by
creating a wrapper library or module that implements the following
functions:

   * `safe_writer_connect()'

   * `safe_reader_connect()'

   * `safe_reader_statement()'

   * `safe_writer_statement()'

`safe_' in each function name means that the function takes care of
handling all error conditions. You can use different names for the
functions. The important thing is to have a unified interface for
connecting for reads, connecting for writes, doing a read, and doing a
write.

Then convert your client code to use the wrapper library. This may be a
painful and scary process at first, but it pays off in the long run.
All applications that use the approach just described are able to take
advantage of a master/slave configuration, even one involving multiple
slaves. The code is much easier to maintain, and adding troubleshooting
options is trivial. You need modify only one or two functions; for
example, to log how long each statement took, or which statement among
those issued gave you an error.

If you have written a lot of code, you may want to automate the
conversion task by using the *Note `replace': replace-utility. utility
that comes with standard MySQL distributions, or write your own
conversion script. Ideally, your code uses consistent programming style
conventions. If not, then you are probably better off rewriting it
anyway, or at least going through and manually regularizing it to use a
consistent style.


File: manual.info,  Node: replication-solutions-partitioning,  Next: replication-solutions-performance,  Prev: replication-solutions-scaleout,  Up: replication-solutions

16.2.4 Replicating Different Databases to Different Slaves
----------------------------------------------------------

There may be situations where you have a single master and want to
replicate different databases to different slaves. For example, you may
want to distribute different sales data to different departments to
help spread the load during data analysis. A sample of this layout is
shown in *Note figure_replication-multi-db::.

FIGURE GOES HERE: Using replication to replicate databases to separate
replication slaves

You can achieve this separation by configuring the master and slaves as
normal, and then limiting the binary log statements that each slave
processes by using the `--replicate-wild-do-table' configuration option
on each slave.

*Important*:

You should _not_ use `--replicate-do-db' for this purpose when using
statement-based replication, since statement-based replication causes
this option's affects to vary according to the database that is
currently selected. This applies to mixed-format replication as well,
since this allows some updates to be replicated using the
statement-based format.

However, it should be to use `--replicate-do-db' for this purpose if
you are using row-based replication only, since in this case the
currently-selected database has no effect on the option's operation.

For example, to support the separation as shown in *Note
figure_replication-multi-db::, you should configure each replication
slave as follows, before executing *Note `START SLAVE': start-slave.:

   * Replication slave 1 should use
     `--replicate-wild-do-table=databaseA.%'.

   * Replication slave 2 should use
     `--replicate-wild-do-table=databaseB.%'.

   * Replication slave 3 should use
     `--replicate-wild-do-table=databaseC.%'.

If you have data that needs to be synchronized to the slaves before
replication starts, you have a number of choices:

   * Synchronize all the data to each slave, and delete the databases,
     tables, or both that you do not want to keep.

   * Use *Note `mysqldump': mysqldump. to create a separate dump file
     for each database and load the appropriate dump file on each slave.

   * Use a raw data file dump and include only the specific files and
     databases that you need for each slave.

     *Note*:

     This does not work with `InnoDB' databases unless you use
     `innodb_file_per_table'.

Each slave in this configuration receives the entire binary log from
the master, but executes only those events from the binary log that
apply to the databases and tables included by the
`--replicate-wild-do-table' option in effect on that slave.


File: manual.info,  Node: replication-solutions-performance,  Next: replication-solutions-switch,  Prev: replication-solutions-partitioning,  Up: replication-solutions

16.2.5 Improving Replication Performance
----------------------------------------

As the number of slaves connecting to a master increases, the load,
although minimal, also increases, as each slave uses up a client
connection to the master. Also, as each slave must receive a full copy
of the master binary log, the network load on the master may also
increase and start to create a bottleneck.

If you are using a large number of slaves connected to one master, and
that master is also busy processing requests (for example, as part of a
scaleout solution), then you may want to improve the performance of the
replication process.

One way to improve the performance of the replication process is to
create a deeper replication structure that enables the master to
replicate to only one slave, and for the remaining slaves to connect to
this primary slave for their individual replication requirements. A
sample of this structure is shown in *Note
figure_replication-performance::.

FIGURE GOES HERE: Using an additional replication host to improve
performance

For this to work, you must configure the MySQL instances as follows:

   * Master 1 is the primary master where all changes and updates are
     written to the database. Binary logging should be enabled on this
     machine.

   * Master 2 is the slave to the Master 1 that provides the
     replication functionality to the remainder of the slaves in the
     replication structure. Master 2 is the only machine allowed to
     connect to Master 1. Master 2 also has binary logging enabled, and
     the `--log-slave-updates' option so that replication instructions
     from Master 1 are also written to Master 2's binary log so that
     they can then be replicated to the true slaves.

   * Slave 1, Slave 2, and Slave 3 act as slaves to Master 2, and
     replicate the information from Master 2, which is really the data
     logged on Master 1.

The above solution reduces the client load and the network interface
load on the primary master, which should improve the overall
performance of the primary master when used as a direct database
solution.

If your slaves are having trouble keeping up with the replication
process on the master then there are a number of options available:

   * If possible, you should put the relay logs and the data files on
     different physical drives. To do this, use the `--relay-log'
     option to specify the location of the relay log.

   * If the slaves are significantly slower than the master, then you
     may want to divide up the responsibility for replicating different
     databases to different slaves. See *Note
     replication-solutions-partitioning::.

   * If your master makes use of transactions and you are not concerned
     about transaction support on your slaves, then use `MyISAM' or
     another non-transactional engine.  See *Note
     replication-solutions-diffengines::.

   * If your slaves are not acting as masters, and you have a potential
     solution in place to ensure that you can bring up a master in the
     event of failure, then you can switch off `--log-slave-updates'.
     This prevents 'dumb' slaves from also logging events they have
     executed into their own binary log.


File: manual.info,  Node: replication-solutions-switch,  Next: replication-solutions-multi-master-upgrade,  Prev: replication-solutions-performance,  Up: replication-solutions

16.2.6 Switching Masters During Failover
----------------------------------------

There is currently no official solution for providing failover between
master and slaves in the event of a failure. With the currently
available features, you would have to set up a master and a slave (or
several slaves), and to write a script that monitors the master to
check whether it is up. Then instruct your applications and the slaves
to change master in case of failure.

Remember that you can tell a slave to change its master at any time,
using the *Note `CHANGE MASTER TO': change-master-to.  statement. The
slave will not check whether the databases on the master are compatible
with the slave, it will just start executing events from the specified
log and position on the new master. In a failover situation all the
servers in the group are probably executing the same events from the
same binary log, so changing the source of the events should not affect
the database structure or integrity providing you are careful.

Run your slaves with the `--log-bin' option and without
`--log-slave-updates'. In this way, the slave is ready to become a
master as soon as you issue *Note `STOP SLAVE': stop-slave.; *Note
`RESET MASTER': reset-master, and *Note `CHANGE MASTER TO':
change-master-to. statement on the other slaves. For example, assume
that you have the structure shown in *Note
figure_replication-redundancy-before::.

FIGURE GOES HERE: Redundancy using replication, initial structure

In this diagram, the `MySQL Master' holds the master database, the
`MySQL Slave' computers are replication slaves, and the `Web Client'
machines are issuing database reads and writes. Web clients that issue
only reads (and would normally be connected to the slaves) are not
shown, as they do not need to switch to a new server in the event of
failure. For a more detailed example of a read/write scaleout
replication structure, see *Note replication-solutions-scaleout::.

Each MySQL Slave (`Slave 1', `Slave 2', and `Slave 3') are slaves
running with `--log-bin' and without `--log-slave-updates'. Because
updates received by a slave from the master are not logged in the
binary log unless `--log-slave-updates' is specified, the binary log on
each slave is empty initially. If for some reason `MySQL Master'
becomes unavailable, you can pick one of the slaves to become the new
master. For example, if you pick `Slave 1', all `Web Clients' should be
redirected to `Slave 1', which will log updates to its binary log.
`Slave 2' and `Slave 3' should then replicate from `Slave 1'.

The reason for running the slave without `--log-slave-updates' is to
prevent slaves from receiving updates twice in case you cause one of the
slaves to become the new master. Suppose that `Slave 1' has
`--log-slave-updates' enabled. Then it will write updates that it
receives from `Master' to its own binary log. When `Slave 2' changes
from `Master' to `Slave 1' as its master, it may receive updates from
`Slave 1' that it has already received from `Master'

Make sure that all slaves have processed any statements in their relay
log. On each slave, issue `STOP SLAVE IO_THREAD', then check the output
of *Note `SHOW PROCESSLIST': show-processlist. until you see `Has read
all relay log'. When this is true for all slaves, they can be
reconfigured to the new setup. On the slave `Slave 1' being promoted to
become the master, issue *Note `STOP SLAVE': stop-slave. and *Note
`RESET MASTER': reset-master.

On the other slaves `Slave 2' and `Slave 3', use *Note `STOP SLAVE':
stop-slave. and `CHANGE MASTER TO MASTER_HOST='Slave1'' (where
`'Slave1'' represents the real host name of `Slave 1'). To use *Note
`CHANGE MASTER TO': change-master-to, add all information about how to
connect to `Slave 1' from `Slave 2' or `Slave 3' (USER, PASSWORD,
PORT). In *Note `CHANGE MASTER TO': change-master-to, there is no need
to specify the name of `Slave 1''s binary log or binary log position to
read from: We know it is the first binary log and position 4, which are
the defaults for *Note `CHANGE MASTER TO': change-master-to. Finally,
use *Note `START SLAVE': start-slave. on `Slave 2' and `Slave 3'.

Once the new replication is in place, you will then need to instruct
each `Web Client' to direct their statements to `Slave 1'. From that
point on, all updates statements sent by `Web Client' to `Slave 1' are
written to the binary log of `Slave 1', which then contains every update
statement sent to `Slave 1' since `Master' died.

The resulting server structure is shown in *Note
figure_replication-redundancy-after::.

FIGURE GOES HERE: Redundancy using replication, after master failure

When `Master' is up again, you must issue on it the same *Note `CHANGE
MASTER TO': change-master-to. as that issued on `Slave 2' and `Slave
3', so that `Master' becomes a slave of `S1' and picks up each `Web
Client' writes that it missed while it was down.

To make `Master' a master again (because it is the most powerful
machine, for example), use the preceding procedure as if `Slave 1' was
unavailable and `Master' was to be the new master. During this
procedure, do not forget to run *Note `RESET MASTER': reset-master. on
`Master' before making `Slave 1', `Slave 2', and `Slave 3' slaves of
`Master'.  Otherwise, they may pick up old `Web Client' writes from
before the point at which `Master' became unavailable.

Note that there is no synchronization between the different slaves to a
master. Some slaves might be ahead of others. This means that the
concept outlined in the previous example might not work. In practice,
however, the relay logs of different slaves will most likely not be far
behind the master, so it would work, anyway (but there is no guarantee).

A good way to keep your applications informed as to the location of the
master is by having a dynamic DNS entry for the master.  With `bind'
you can use `nsupdate' to dynamically update your DNS.


File: manual.info,  Node: replication-solutions-multi-master-upgrade,  Next: replication-solutions-ssl,  Prev: replication-solutions-switch,  Up: replication-solutions

16.2.7 Upgrading Multi-Master Replication
-----------------------------------------

This section discusses how to upgrade the MySQL server software on
several machines in a multi-master replication setup from an older
version to a newer version of the software without taking the entire
system offline. The procedure outlined here is intended to be
illustrative and not necessarily to be followed exactly as written in
all possible scenarios.

There are two sorts of configurations for replication involving
multiple masters:

   * Linear replication

     In this type of setup, one or more masters replicates to a single
     slave. The simplest linear replication topology is shown here,
     where a single master A replicates to a single slave B:

     Simplest case: single master replicates to single slave

     Of greater interest are cases where we actually have multiple
     masters, such as

     when we have a chain of MySQL servers, some of which are acting as
     both masters and slaves. The following diagram depicts server A
     replicating to B, which in turn replicates to C; here, B acts as
     both a master and a slave:

     Several MySQL servers replicate to one another in turn

     In

     this case, the procedure for performing a software upgrade can be
     developed from the simple principle `upgrade the slave first, then
     the master'. In other words,

     we should

     start by upgrading the server that acts only as a slave (C), then
     upgrading its master (B), and so on, until we reach the server
     acting as a master only (A), upgrade it, and so complete the
     process. This can easily be extended to cover an arbitrary number
     of MySQL servers, as shown here:

     Arbitrarily long chain of replication masters and slaves

   * Circular replication

     In a circular replication setup, _each_ MySQL server acts as both
     a master and a slave; thus, there is no `last' server which we can
     use as a starting point to apply `upgrade the slave first, then
     the master'. We therefore require a different approach to
     performing the upgrade, and it is for this reason that the rest of
     this section is devoted to a discussion of upgrading the MySQL
     server software on several hosts configured in a circular
     replication setup.

Basic scenario

Assume that we have three servers, A, B, and C, running MySQL version
6.0, replicating in a circle, as shown in this diagram:

Circular replication with 3 MySQL servers

Our objective is to upgrade, in turn, all three machines from one MySQL
version (for example, MySQL 5.1) to a newer MySQL version (such as
MySQL 6.0) without taking the system as a whole out of production. We
start with server C, which acts as a slave of server B and a master to
server A.

To upgrade this server, we need to perform the following steps:

  1. Stop C

     On C, execute the statement

          STOP SLAVE;

  2. Create a `marker' event on B

     Execute a statement on B that generates an event which is easily
     identified. For this example, we assume that there is no existing
     table named `marker' in the `test' database, and perform the
     following statements to create it:

          USE test;
          CREATE TABLE marker1 (col INT);

     The table schema is completely arbitrary; in fact, the statement
     is itself completely arbitrary. The only requirement is that we
     use an SQL statement that is unique and easily identifiable for
     use as the `marker'.

  3. Find the position of the marker in the binary log

     This can be done by executing *Note `SHOW BINLOG EVENTS':
     show-binlog-events. on B, then checking the `Info' column in the
     output for an event containing the `marker' statement. Note the
     values of the `Log_name' and `Pos' columns, which are needed for
     the next step, where we refer to these values as FILEB and POSB,
     respectively.

  4. Allow C to catch up to the marker

     Execute the following statements on C:

          START SLAVE UNTIL
              MASTER_LOG_FILE=FILEB,
              MASTER_LOG_POS=POSB;

          SELECT MASTER_POS_WAIT(FILEB, POSB);

     This causes C to execute any remaining events sent from B up to
     the point where the `marker' statement was issued, and then to
     stop. The place of the marker in the sequence of events flowing
     from B to C is illustrated here:

     `Marker' event created on server B in the flow of events from B to
     C

  5. Take server C offline

     Ensure that no further actions capable of updating the binary log
     can be taken on C:

        * Redirect any clients using C to A or B. This is best handled
          in application code. Additionally, you may wish to use the
          *Note `SHOW PROCESSLIST': show-processlist. and *Note `KILL':
          kill. statements, as the MySQL `root' user or as another user
          with the `SUPER' privilege, to terminate any remaining client
          processes other than the one you are using to perform tasks
          on C relating to the software upgrade.

          You can prevent any application clients from reconnecting to
          C by executing the following statement as MySQL `root' (or
          another user having the `SUPER' privilege):

               SET @@GLOBAL.MAX_CONNECTIONS = 1;

          Once this has been done, only a single client, having the
          `SUPER' privilege, may connect to C. This works because
          `max_connections + 1' clients are allowed to connect to the
          server, with one of these connections being reserved for a
          client having the `SUPER' privilege.  Therefore, when
          `max_connections' is equal to 1, and no other clients are
          connected, a maximum of 1 client _not_ having `SUPER' may
          connect.  However, a client not having the `SUPER' privilege
          cannot use the extra connection. This means that, when
          `max_connections' is `1' and a client having `SUPER' is
          already connected, no non-`SUPER' clients may connect connect
          to the server.

        * Force all tables to be read-only by executing the following
          statement:

               SET @@GLOBAL.READ_ONLY = ON;

          As an alternative, you can use the following statement, which
          is equivalent to the previous one:

               SET @@GLOBAL.READ_ONLY = 1;

          This places the server into `read-only' mode, which prevents
          any accidental changes to tables on C.

        * Stop the MySQL Event Scheduler on server C by executing the
          following statement:

               SET @@GLOBAL.EVENT_SCHEDULER = OFF;

          This is necessary since the Event Scheduler can perform
          actions that result in writes to the binary log, which could
          cause the binary log on C to diverge from the binary logs on
          the other servers in unexpected ways.

  6. Find the end of the last binary log on C

     This can be accomplished by executing *Note `SHOW MASTER STATUS':
     show-master-status. on C and noting the values shown in the `File'
     and `Position' columns of the output, which we show as FILEC and
     POSC, respectively, in the next step.

  7. Stop and synchronize slave A

     Execute *Note `STOP SLAVE': stop-slave. on A.  Then perform the
     following statements:

          START SLAVE UNTIL
              MASTER_LOG_FILE=FILEC,
              MASTER_LOG_POS=POSC;

          SELECT MASTER_POS_WAIT(FILEC, POSC);

     This causes any remaining unprocessed events up the marker event
     on C to be executed on A, and causes A to stop once this has been
     done. The propagation of the marker from server C to server A is
     shown here:

     Marker event propagates from server C to server A

     This is not the same marker as the previous one -- in fact, the
     best `marker' to use here is the end of C's binary log.

  8. Start replication from B to A

     You can cause A to replicate from B instead of from C by issuing
     the following 2 statements on server A:

          CHANGE MASTER TO
              MASTER_HOST=HOSTB,
              MASTER_LOG_FILE=FILEB,
              MASTER_LOG_POS=POSB;

          START SLAVE;

     In the first of these statements, HOSTB represents the host name
     or IP address for server B; FILEB and POSB are the same as
     determined for these values earlier

     C is now isolated from the other two servers, which are now
     replicating to each other, as shown here:

     Servers A and B in mutual replication; server C isolated

  9. Upgrade C to C'

     Shut down C, and upgrade the MySQL software on C from version X to
     version Y:

     Upgrading Server C running MySQL version X to C', running MySQL
     version Y

     We refer to the upgraded server C as _C'_.

     For general information about performing upgrades, see the
     `Upgrading MySQL' section of the `MySQL Manual' corresponding to
     the versions from which and to which you are upgrading.

 10. Start C' in offline mode

     Start server C', insuring that all its tables are in read-only
     mode, and that no MySQL clients (with the exception of a single
     connection from a superuser account) can connect to it. You can do
     this by starting *Note `mysqld': mysqld. with the options
     `--read_only' `--max_connections=1'. (For more information about
     these options, see *Note server-system-variables::.)

 11. Stop replicating from B to A

     Stop sending events from B to A, and ensure that A has executed
     all events sent to it from B:

        * Issue a *Note `STOP SLAVE': stop-slave. on A

        * Issue a marker statement on B, such as this one:

               CREATE TABLE test.marker2 (col INT);

          As with the previous marker statement, the type and any other
          aspects of the statement are completely arbitrary; the only
          requirement is that the statement must be uniquely
          identifiable.

        * Use *Note `SHOW BINLOG EVENTS': show-binlog-events. on B to
          find the binary log file and position where the marker event
          was recorded, as described previously. We use FILEB' and
          POSB' to denote these in the next item.

        * Start server A and synchronize it with B by issuing the
          following statements on A:

               START SLAVE UNTIL
                   MASTER_LOG_FILE=FILEB',
                   MASTER_LOG_POS=POSB';

               SELECT MASTER_POS_WAIT(FILEB', POSB');

          Once A has executed all events up to and including the second
          marker event, it stops, as shown here:

          Second marker event propagates from server B to server A

 12. Start replicating from B to C'

     Start sending events from B to C' and executing them on C'
     (indicated by the dotted line in the next diagram), ensuring that
     the first event not sent to A is the first event sent to C'. You
     can do this by issuing the following statements on C':

          SET @@GLOBAL.READ_ONLY = OFF;

          CHANGE MASTER TO
              MASTER_HOST=HOSTB,
              MASTER_LOG_FILE=FILEB',
              MASTER_LOG_POS=POSB';

          START SLAVE;

     Replication now occurs as shown here:

     Server B now replicates to server C'

 13. Start replicating from C' to A

     This can be done as follows:

        * Locate the file and position of the second marker event in
          the binary log on server C'. This can be found by issuing
          *Note `SHOW BINLOG EVENTS': show-binlog-events. on C' as
          previously described.

          We denote the file and position within this file as FILEC' and
          POSC', respectively.

        * Start replication on A from this point by issuing the
          following statements, where HOSTC' represents the host name
          or IP address of server C', and FILEC' and POSC' are defined
          as stated in the previous item:

               CHANGE MASTER TO
                   MASTER_HOST=HOSTC',
                   MASTER_LOG_FILE=FILEC',
                   MASTER_LOG_POS=POSC';

               START SLAVE;

 14. Return server C to online status

     This can be done by setting `@@GLOBAL.MAX_CONNECTIONS' to an
     appropriate value greater than `1', thereby once again permitting
     regular clients not having the `SUPER' privilege to connect.

At this point, the original replication topology has been restored, and
all is as before, except that server C running MySQL version X has been
upgrade to C' running MySQL version Y, as shown here:

The circular replication topology is now restored, with server A
replicating to server B, server B replicating to server C', and server
C' replicating to server A

You can now complete the software upgrade process by repeating the
steps shown previously for servers A and B, each in turn.


File: manual.info,  Node: replication-solutions-ssl,  Next: replication-semisync,  Prev: replication-solutions-multi-master-upgrade,  Up: replication-solutions

16.2.8 Setting Up Replication Using SSL
---------------------------------------

Setting up replication using an SSL connection is similar to setting up
a server and client using SSL. You will need to obtain (or create) a
suitable security certificate that you can use on the master, and a
similar certificate (from the same certificate authority) on each slave.

To use SSL for encrypting the transfer of the binary log required
during replication you must first set up the master to support SSL
network connections. If the master does not support SSL connections
(because it has not been compiled or configured for SSL), then
replication through an SSL connection will not be possible.

For more information on setting up a server and client for SSL
connectivity, see *Note secure-using-ssl::.

To enable SSL on the master you will need to create or obtain suitable
certificates and then add the following configuration options to the
master's configuration within the `mysqld' section:

     ssl-ca=CACERT.PEM
     ssl-cert=SERVER-CERT.PEM
     ssl-key=SERVER-KEY.PEM

*Note*:

You should use full path to specify the location of your certificate
files.

The options are as follows:

   * `ssl-ca' identifies the Certificate Authority (CA) certificate.

   * `ssl-cert' identifies the server public key.  This can be sent to
     the client and authenticated against the CA certificate that it
     has.

   * `ssl-key' identifies the server private key.

On the slave, you have two options available for setting the SSL
information. You can either add the slaves certificates to the `client'
section of the slave configuration file, or you can explicitly specify
the SSL information using the *Note `CHANGE MASTER TO':
change-master-to. statement.

Using the former option, add the following lines to the `client'
section of the slave configuration file:

     [client]
     ssl-ca=CACERT.PEM
     ssl-cert=SERVER-CERT.PEM
     ssl-key=SERVER-KEY.PEM

Restart the slave server, using the `--skip-slave' to prevent the slave
from connecting to the master. Use *Note `CHANGE MASTER TO':
change-master-to. to specify the master configuration, using the
`master_ssl' option to enable SSL connectivity:

     mysql> CHANGE MASTER TO \
         MASTER_HOST='master_hostname', \
         MASTER_USER='replicate', \
         MASTER_PASSWORD='password', \
         MASTER_SSL=1;

To specify the SSL certificate options during the *Note `CHANGE MASTER
TO': change-master-to. command, append the SSL options:

     CHANGE MASTER TO \
           MASTER_HOST='master_hostname', \
           MASTER_USER='replicate', \
           MASTER_PASSWORD='password', \
           MASTER_SSL=1, \
           MASTER_SSL_CA = 'ca_file_name', \
           MASTER_SSL_CAPATH = 'ca_directory_name', \
           MASTER_SSL_CERT = 'cert_file_name', \
           MASTER_SSL_KEY = 'key_file_name';

Once the master information has been updated, start the slave
replication process:

     mysql> START SLAVE;

You can use the *Note `SHOW SLAVE STATUS': show-slave-status.  to
confirm that SSL connection has been completed.

For more information on the *Note `CHANGE MASTER TO': change-master-to.
syntax, see *Note change-master-to::.

If you want to enforce SSL connections to be used during replication,
then create a user with the `REPLICATION SLAVE' privilege and use the
`REQUIRE_SSL' option for that user. For example:

     mysql> GRANT REPLICATION SLAVE ON *.*
         -> TO 'repl'@'%.mydomain.com' IDENTIFIED BY 'slavepass' REQUIRE SSL;


File: manual.info,  Node: replication-semisync,  Prev: replication-solutions-ssl,  Up: replication-solutions

16.2.9 Semisynchronous Replication
----------------------------------

* Menu:

* replication-semisync-interface::  Semisynchronous Replication Administrative Interface
* replication-semisync-installation::  Semisynchronous Replication Installation and Configuration
* replication-semisync-monitoring::  Semisynchronous Replication Monitoring

MySQL 6.0 supports an interface to semisynchronous replication in
addition to the built-in asynchronous replication.  This section
discusses what semisynchronous replication is and how it works. The
following sections cover the adminstrative interface to semisynchronous
replication and how to install, configure, and monitor it.

MySQL replication by default is asynchronous. The master writes events
to its binary log but does not know whether or when a slave has
retrieved and processed them. With asynchronous replication, if the
master crashes, transactions that it has committed might not have been
transmitted to any slave. Consequently, failover from master to slave
in this case may result in failover to a server that is missing
transactions relative to the master.

As of MySQL 6.0.8, semisynchronous replication can be used instead:

   * A slave indicates whether it is semisynchronous-capable when it
     connects to the master.

   * If semisynchronous replication is enabled on the master side and
     there is at least one semisynchronous slave, a thread that
     performs a transaction commit on the master blocks after the
     commit is done and waits until at least one semisynchronous slave
     acknowledges that it has received all events for the transaction,
     or until a timeout occurs.

   * The slave acknowledges receipt of a transaction's events only
     after the events have been written to its relay log and flushed to
     disk.

   * If a timeout occurs without any slave having acknowledged the
     transaction, the master reverts to asynchronous replication.  When
     at least one semisynchronous slave catches up, the master returns
     to semisynchronous replication.

   * Semisynchronous replication must be enabled on both the master and
     slave sides. If semisynchronous replication is disabled on the
     master, or enabled on the master but on no slaves, the master uses
     asynchronous replication.

While the master is blocking (waiting for acknowledgment from a slave
after having performed a commit), it does not return to the session
that performed the transaction. When the block ends, the master returns
to the session, which then can proceed to execute other statements. At
this point, the transaction has committed on the master side, and
receipt of its events has been acknowledged by at least one slave.

Blocking also occurs after rollbacks that are written to the binary
log, which occurs when a transaction that modifies non-transactional
tables is rolled back. The rolled-back transaction is logged even
though it has no effect for transactional tables because the
modifications to the non-transactional tables cannot be rolled back and
must be sent to slaves.

For statements that do not occur in transactional context (that is,
when no transaction has been started with *Note `START TRANSACTION':
commit. or `SET autocommit = 0'), autocommit is enabled and each
statement commits implicitly. With semisynchronous replication, the
master blocks after committing each such statement, just as it does for
explicit transaction commits.

To understand what the `semi' in `semisynchronous replication' means,
compare it with asynchronous and fully synchronous replication:

   * With asynchronous replication, the master writes events to its
     binary log and slaves request them when they are ready. There is
     no guarantee that any event will ever reach any slave.

   * With fully synchronous replication, when a master commits a
     transaction, all slaves also will have committed the transaction
     before the master returns to the session that performed the
     transaction. The drawback of this is that there might be a lot of
     delay to complete a transaction.

   * Semisynchronous replication falls between asynchronous and fully
     synchronous replication. The master waits after commit only until
     at least one slave has received and logged the events. It does not
     wait for all slaves to acknowledge receipt, and it requires only
     receipt, not that the events have been fully executed and
     committed on the slave side.

Compared to asynchronous replication, semisynchronous replication
provides improved data integrity. When a commit returns successfully,
it is known that the data exists in at least two places (on the master
and at least one slave). If the master commits but a crash occurs while
the master is waiting for acknowledgment from a slave, it is possible
that the transaction may not have reached any slave.

Semisynchronous replication does have some performance impact because
commits are slower due to the need to wait for slaves.  This is the
tradeoff for increased data integrity. The amount of slowdown is at
least the TCP/IP roundtrip time to send the commit to the slave and
wait for the acknowledgment of receipt by the slave. This means that
semisynchronous replication works best for close servers communicating
over fast networks, and worst for distant servers communicating over
slow networks.


File: manual.info,  Node: replication-semisync-interface,  Next: replication-semisync-installation,  Prev: replication-semisync,  Up: replication-semisync

16.2.9.1 Semisynchronous Replication Administrative Interface
.............................................................

The administrative interface to semisynchronous replication has several
components:

   * Two plugins implement semisynchronous capability. There is one
     plugin for the master side and one for the slave side.

   * System variables control plugin behavior:

        * `rpl_semi_sync_master_enabled'

          Controls whether semisynchronous replication is enabled on
          the master. To enable or disable the plugin, set this
          variable to 1 or 0, respectively. The default is 1.

        * `rpl_semi_sync_master_timeout'

          A value in seconds that controls how long the master waits on
          a commit for acknowledgment from a slave before timing out
          and reverting to asynchronous replication.  The default value
          is 10 seconds.

        * `rpl_semi_sync_slave_enabled'

          Similar to `rpl_semi_sync_master_enabled', but controls the
          slave plugin.

   * Status variables enable semisynchronous replication monitoring:

        * `Rpl_semi_sync_master_clients'

          The number of semisynchronous slaves.

        * `Rpl_semi_sync_master_status'

          Whether semisynchronous replication currently is operational
          on the master. The value is 1 if the plugin has been enabled
          and a commit acknowledgment has not occurred. It is 0 if the
          plugin is not enabled or the master has fallen back to
          asynchronous replication due to commit acknowledgment timeout.

        * `Rpl_semi_sync_master_no_tx'

          The number of commits that were not acknowledged successfully
          by a slave.

        * `Rpl_semi_sync_master_yes_tx'

          The number of commits that were acknowledged successfully by
          a slave.

        * `Rpl_semi_sync_slave_status'

          Whether semisynchronous replication currently is operational
          on the slave. This is 1 if the plugin has been enabled and
          the slave I/O thread is running, 0 otherwise.

The system and status variables are available only if the appropriate
master or slave plugin has been installed with *Note `INSTALL PLUGIN':
install-plugin.


File: manual.info,  Node: replication-semisync-installation,  Next: replication-semisync-monitoring,  Prev: replication-semisync-interface,  Up: replication-semisync

16.2.9.2 Semisynchronous Replication Installation and Configuration
...................................................................

Semisynchronous replication is implemented using plugins, so the
plugins must be installed into the server to make them available. After
a plugin has been installed, you control it by means of the system
variables associated with it. These system variables are unavailable
until the associated plugin has been installed.

To use semisynchronous replication, the following requirements must be
satisfied:

   * MySQL 6.0.8 or higher must be installed.

   * The capability of installing plugins requires a MySQL server that
     supports dynamic loading. To verify this, check that the value of
     the `have_dynamic_loading' system variable is `YES'. Binary
     distributions should support dynamic loading. If you compile MySQL
     from source, do not configure the source distribution with the
     `--with-mysqld-ldflags=-all-static' option.

   * Replication must already be working. For information on creating a
     master/slave relationship, see *Note replication-howto::.

To set up semisynchronous replication, use the following instructions.
The *Note `INSTALL PLUGIN': install-plugin, *Note `SET GLOBAL':
set-option, *Note `STOP SLAVE': stop-slave, and *Note `START SLAVE':
start-slave. statements mentioned here require the `SUPER' privilege.

Obtain the semisynchronous replication plugins. They are not included
with MySQL distributions. Instead, they are distributed as a separate
component. The initial preview release may be obtained from
`http://downloads.mysql.com/forge/replication_preview'.

Currently, the plugins are available only for Linux. Other platforms
are is not yet supported.

Unpack the component distribution, which contains files for the master
side and the slave side.

Install the component files in the plugin directory of the appropriate
server. Install the `libsemisync_master*' files in the plugin directory
of the master server. Install the `libsemisync_slave*' files in the
plugin directory of each slave server. The location of the plugin
directory is available as the value of the server's `plugin_dir' system
variable.

To load the plugins, use the *Note `INSTALL PLUGIN': install-plugin.
statement on the master and on each slave that is to be semisynchronous.

On the master:

     mysql> INSTALL PLUGIN rpl_semi_sync_master SONAME 'libsemisync_master.so';

On each slave:

     mysql> INSTALL PLUGIN rpl_semi_sync_slave SONAME 'libsemisync_slave.so';

The preceding commands use a plugin file name suffix of `.so'. A
different suffix might apply on your system. If you are not sure about
the plugin file name, look for the plugins in the server's plugin
directory.

To see which plugins are installed, use the *Note `SHOW PLUGINS':
show-plugins. statement, or query the *Note
`INFORMATION_SCHEMA.PLUGINS': plugins-table.  table.

After a semisynchronous replication plugin has been installed, it is
enabled by default. The plugins must be enabled both on the master side
and the slave side to enable semisynchronous replication. If only one
side is enabled, replication will be asynchronous.

To control an installed plugin, set the appropriate system variables.
You can set these variables at runtime using *Note `SET GLOBAL':
set-option, or at server startup on the command line or in an option
file.

At runtime, these master-side system variables are available:

     mysql> SET GLOBAL rpl_semi_sync_master_enabled = {0|1};
     mysql> SET GLOBAL rpl_semi_sync_master_timeout = N;

On the slave side, this system variable is available:

     mysql> SET GLOBAL rpl_semi_sync_slave_enabled = {0|1};

For `rpl_semi_sync_master_enabled' or `rpl_semi_sync_slave_enabled',
the value should be 1 to enable semisynchronous replication or 0 to
disable it. By default, these variables are set to 1.

For `rpl_semi_sync_master_timeout', the value N is given in seconds. The
default value is 10.

If you enable semisynchronous replication on a slave at runtime, you
must also start the slave I/O thread (stopping it first if it is
already running) to cause the slave to connect to the master and
register as a semisynchronous slave:

     mysql> STOP SLAVE IO_THREAD; START SLAVE IO_THREAD;

If the I/O thread is already running and you do not restart it, the
slave continues to use asynchronous replication.

At server startup, the variables that control semisynchronous
replication can be set as command-line options or in an option file. A
setting listed in an option file takes effect each time the server
starts. For example, you can set the variables in `my.cnf' files on the
master and slave sides as follows.

On the master:

     [mysqld]
     rpl_semi_sync_master_enabled=1
     rpl_semi_sync_master_timeout=10

On each slave:

     [mysqld]
     rpl_semi_sync_slave_enabled=1


File: manual.info,  Node: replication-semisync-monitoring,  Prev: replication-semisync-installation,  Up: replication-semisync

16.2.9.3 Semisynchronous Replication Monitoring
...............................................

The plugins for the semisynchronous replication capability expose
several system and status variables that you can examine to determine
its configuration and operational state.

The system variable reflect how semisynchronous replication is
configured. To check their values, use *Note `SHOW VARIABLES':
show-variables.:

     mysql> SHOW VARIABLES LIKE 'rpl_semi_sync%';

The status variables enable you to monitor the operation of
semisynchronous replication. To check their values, use *Note `SHOW
STATUS': show-status.:

     mysql> SHOW STATUS LIKE 'Rpl_semi_sync%';

When the master switches between asynchronous or semisynchronous
replication due to commit-blocking timeout or a slave catching up, it
sets the value of the `Rpl_semi_sync_master_status' status variable
appropriately. Automatic fallback from semisynchronous to asynchronous
replication on the master means that it is possible for the
`rpl_semi_sync_master_enabled' system variable to have a value of 1 on
the master side even when semisynchronous replication is in fact not
operational at the moment. You can monitor the
`Rpl_semi_sync_master_status' status variable to determine whether the
master currently is using asynchronous or semisynchronous replication.

To see how many semisynchronous slaves are connected, check
`Rpl_semi_sync_master_clients'.

The number of commits that have been acknowledged successfully or
unsucessfully by slaves are indicated by the
`Rpl_semi_sync_master_yes_tx' and `Rpl_semi_sync_master_no_tx'
variables.

On the slave side, `Rpl_semi_sync_slave_status' indicates whether
semisynchronous replication currently is operational.


File: manual.info,  Node: replication-notes,  Next: replication-implementation,  Prev: replication-solutions,  Up: replication

16.3 Replication Notes and Tips
===============================

* Menu:

* replication-features::         Replication Features and Issues
* replication-compatibility::    Replication Compatibility Between MySQL Versions
* replication-upgrade::          Upgrading a Replication Setup
* replication-faq::              Replication FAQ
* replication-problems::         Troubleshooting Replication
* replication-bugs::             How to Report Replication Bugs or Problems


File: manual.info,  Node: replication-features,  Next: replication-compatibility,  Prev: replication-notes,  Up: replication-notes

16.3.1 Replication Features and Issues
--------------------------------------

* Menu:

* replication-features-auto-increment::  Replication and `AUTO_INCREMENT'
* replication-features-charset::  Replication and Character Sets
* replication-features-create-select::  Replication of `CREATE TABLE ... SELECT' Statements
* replication-features-differing-tables::  Replication with Differing Tables on Master and Slave
* replication-features-directory::  Replication and `DIRECTORY' Table Options
* replication-features-drop-if-exists::  Replication of `DROP ... IF EXISTS' Statements
* replication-features-invoked::  Replication of Invoked Features
* replication-features-floatvalues::  Replication with Floating-Point Values
* replication-features-flush::   Replication and `FLUSH'
* replication-features-functions::  Replication and System Functions
* replication-features-limit::   Replication and `LIMIT'
* replication-features-load-data::  Replication and `LOAD DATA'
* replication-features-logging::  Replication and the Slow Query Log
* replication-features-mastercrash::  Replication During a Master Crash
* replication-features-mastershutdown::  Replication During a Master Shutdown
* replication-features-memory::  Replication with `MEMORY' Tables
* replication-features-mysqldb::  Replication of the System `mysql' Database
* replication-features-optimizer::  Replication and the Query Optimizer
* replication-features-reserved-words::  Replication and Reserved Words
* replication-features-slaveerrors::  Slave Errors during Replication
* replication-features-slaveshutdown::  Replication during a Slave Shutdown
* replication-features-temptables::  Replication and Temporary Tables
* replication-features-timeout::  Replication Retries and Timeouts
* replication-features-timezone::  Replication and Time Zones
* replication-features-transactions::  Replication and Transactions
* replication-features-triggers::  Replication and Triggers
* replication-features-truncate::  Replication and `TRUNCATE'
* replication-features-variables::  Replication and Variables
* replication-features-views::   Replication and Views

The following sections provide information about what is supported and
what is not in MySQL replication, and about specific issues and
situations that may occur when replicating certain statements.

Statement-based replication depends on compatibility at the SQL level
between the master and slave. In others, successful SBR requires that
any SQL features used be supported by both the master and the slave
servers. For example, if you use a feature on the master server that is
available only in MySQL 6.0 (or later), you cannot replicate to a slave
that uses MySQL 5.1 (or earlier).

Such incompatibilities also can occur within a release series when
using pre-production releases of MySQL. For example, the `SLEEP()'
function is available beginning with MySQL 5.0.12. If you use this
function on the master, you cannot replicate to a slave that uses MySQL
5.0.11 or earlier.

For this reason, we recommend that you use Generally Available (GA)
releases of MySQL for statement-based replication in a production
setting, since we do not introduce new SQL statements or change their
behavior within a given release series once that series reaches GA
release status.

If you are planning to use statement-based replication between MySQL
6.0 and a previous MySQL release series, it is also a good idea to
consult the edition of the `MySQL Reference Manual' corresponding to
the earlier release series for information regarding the replication
characteristics of that series.

With MySQL's classic statement-based replication, there may be issues
with replicating stored routines or triggers. You can avoid these
issues by using MySQL's row-based replication instead. For a detailed
list of issues, see *Note stored-programs-logging::. For more
information about row-based replication, see *Note
replication-formats::.

For additional information specific to replication and `InnoDB', see
*Note innodb-and-mysql-replication::. For information relating to
replication with MySQL Cluster, see MySQL Cluster Replication
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-replication.html).


File: manual.info,  Node: replication-features-auto-increment,  Next: replication-features-charset,  Prev: replication-features,  Up: replication-features

16.3.1.1 Replication and `AUTO_INCREMENT'
.........................................

Statement-based replication of `AUTO_INCREMENT', `LAST_INSERT_ID()', and
*Note `TIMESTAMP': datetime. values is done correctly, subject to the
following exceptions:

   * A stored procedure that uses `LAST_INSERT_ID()' does not replicate
     properly using statement-based binary logging.  This limitation is
     lifted in MySQL 5.1.12.

   * Prior to MySQL 5.1.12, when a stored routine or trigger caused an
     *Note `INSERT': insert. into an `AUTO_INCREMENT' column, the
     generated `AUTO_INCREMENT' value was not written into the binary
     log, so a different value could in some cases be inserted on the
     slave.

   * An insert into an `AUTO_INCREMENT' column caused by a stored
     routine or trigger running on a master that uses MySQL 5.0.60 or
     earlier does not replicate correctly to a slave running MySQL
     5.1.12 through 5.1.23 (inclusive). (Bug#33029
     (http://bugs.mysql.com/33029))

   * Table-level `AUTO_INCREMENT' option values were not replicated
     correctly prior to MySQL 6.0.10. (Bug#41986
     (http://bugs.mysql.com/41986))

   * Adding an `AUTO_INCREMENT' column to a table with *Note `ALTER
     TABLE': alter-table. might not produce the same ordering of the
     rows on the slave and the master. This occurs because the order in
     which the rows are numbered depends on the specific storage engine
     used for the table and the order in which the rows were inserted.
     If it is important to have the same order on the master and slave,
     the rows must be ordered before assigning an `AUTO_INCREMENT'
     number. Assuming that you want to add an `AUTO_INCREMENT' column to
     the table `t1', the following statements produce a new table `t2'
     identical to `t1' but with an `AUTO_INCREMENT' column:

          CREATE TABLE t2 LIKE t1;
          ALTER TABLE t2 ADD id INT AUTO_INCREMENT PRIMARY KEY;
          INSERT INTO t2 SELECT * FROM t1 ORDER BY col1, col2;

     This assumes that the table `t1' has columns `col1' and `col2'.

     *Important*:

     To guarantee the same ordering on both master and slave, _all_
     columns of `t1' must be referenced in the `ORDER BY' clause.

     The instructions just given are subject to the limitations of
     `CREATE TABLE ... LIKE': Foreign key definitions are ignored, as
     are the `DATA DIRECTORY' and `INDEX DIRECTORY' table options. If a
     table definition includes any of those characteristics, create
     `t2' using a *Note `CREATE TABLE': create-table. statement that is
     identical to the one used to create `t1', but with the addition of
     the `AUTO_INCREMENT' column.

     Regardless of the method used to create and populate the copy
     having the `AUTO_INCREMENT' column, the final step is to drop the
     original table and then rename the copy:

          DROP t1;
          ALTER TABLE t2 RENAME t1;

     See also *Note alter-table-problems::.


File: manual.info,  Node: replication-features-charset,  Next: replication-features-create-select,  Prev: replication-features-auto-increment,  Up: replication-features

16.3.1.2 Replication and Character Sets
.......................................

The following applies to replication between MySQL servers that use
different character sets:

  1. If the master uses MySQL 4.1, you must _always_ use the same
     _global_ character set and collation on the master and the slave,
     regardless of the MySQL version running on the slave. (These are
     controlled by the `--character-set-server' and
     `--collation-server' options.)  Otherwise, you may get
     duplicate-key errors on the slave, because a key that is unique in
     the master character set might not be unique in the slave
     character set. Note that this is not a cause for concern when
     master and slave are both MySQL 5.0 or later.

  2. If the master is older than MySQL 4.1.3, the character set of any
     client should never be made different from its global value
     because this character set change is not known to the slave. In
     other words, clients should not use `SET NAMES', `SET CHARACTER
     SET', and so forth. If both the master and the slave are 4.1.3 or
     newer, clients can freely set session values for character set
     variables because these settings are written to the binary log and
     so are known to the slave. That is, clients can use `SET NAMES' or
     `SET CHARACTER SET' or can set variables such as
     `collation_client' or `collation_server'. However, clients are
     prevented from changing the _global_ value of these variables; as
     stated previously, the master and slave must always have identical
     global character set values. This is true whether you are using
     statement-based or row-based replication.

  3. If you have databases on the master with character sets that
     differ from the global `character_set_server' value, you should
     design your *Note `CREATE TABLE': create-table. statements so that
     tables in those databases do not implicitly rely on the database
     default character set. A good workaround is to state the character
     set and collation explicitly in *Note `CREATE TABLE':
     create-table. statements.


File: manual.info,  Node: replication-features-create-select,  Next: replication-features-differing-tables,  Prev: replication-features-charset,  Up: replication-features

16.3.1.3 Replication of `CREATE TABLE ... SELECT' Statements
............................................................

This section discusses the rules that are applied when a `CREATE TABLE
... SELECT' statement is replicated.

*Note*:

`CREATE TABLE ... SELECT' always performs an implicit commit (*Note
implicit-commit::).

Statement succeeds

If the `CREATE TABLE ... SELECT' statement succeeds on the master, then
it is replicated as follows:

   * `STATEMENT' or `MIXED' format

     The `CREATE TABLE ... SELECT' statement is itself replicated.

   * `ROW' format

     The statement is replicated as a *Note `CREATE TABLE':
     create-table. statement followed by a series of `binwrite' events
     (that is, binary inserts).

Statement fails

The failure of a `CREATE TABLE ... SELECT' is handled according to the
following criteria:

   * No `IF NOT EXISTS' option

     If the `CREATE TABLE ... SELECT' does not contain an `IF NOT
     EXISTS' option, then the statement has no effect. However, the
     implicit commit caused by the statement is logged.  This is true
     regardless of the replication format, storage engine used, and the
     reason for which the statement failed.

   * Statement uses `IF NOT EXISTS'

     If the `CREATE TABLE ... SELECT' statement includes the `IF NOT
     EXISTS' option and fails, the failure is handled according to the
     replication format. If the row-based format is in use, the action
     taken depends additionally on whether or not the table to be
     created uses a transactional or non-transactional storage engine,
     and on the reason for the failure:

        * `STATEMENT' or `MIXED' format

          When using statement-based or mixed-format replication, the
          `CREATE TABLE IF NOT EXISTS ... SELECT' is logged with an
          error.

        * `ROW' format

          When row-based replication is used, failure of a `CREATE
          TABLE ... SELECT' that includes `IF NOT EXISTS' is handled
          differently depending on the reason for the failure, as shown
          in the following diagram:

          `CREATE TABLE IF NOT EXISTS ... SELECT' Failure Handling (RBR)


File: manual.info,  Node: replication-features-differing-tables,  Next: replication-features-directory,  Prev: replication-features-create-select,  Up: replication-features

16.3.1.4 Replication with Differing Tables on Master and Slave
..............................................................

* Menu:

* replication-features-more-columns::  Replication with More Columns on Master or Slave
* replication-features-different-data-types::  Replication of Columns Having Different Data Types

Source and target tables for replication do not have to be identical. A
table on the master can have more or fewer columns than the slave's
copy of the table. In addition -- subject to certain conditions --
corresponding table columns on the master and the slave can use
different data types.

In all cases where the source and target tables do not have identical
definitions, the following must be true in order for replication to
work:

   * You must be using row-based replication. (Using `MIXED' for the
     binary logging format does not work.)

   * The database and table names must be the same on both the master
     and the slave.

Additional conditions are discussed (and examples provided) in the
following two sections.


File: manual.info,  Node: replication-features-more-columns,  Next: replication-features-different-data-types,  Prev: replication-features-differing-tables,  Up: replication-features-differing-tables

16.3.1.5 Replication with More Columns on Master or Slave
.........................................................

You can replicate a table from the master to the slave such that the
master's copy of the table and the slave's copy of the table do not
have the same number of columns, subject to the following conditions:

   * Each `extra' column in the version of the table having more
     columns must have a default value.

     *Note*:

     A column's default value is determined by a number of factors,
     including its type, whether it is defined with a `DEFAULT' option,
     whether it is declared as `NULL', and the server SQL mode in
     effect at the time of its creation; see *Note
     data-type-defaults::), for more information.

   * Matching columns must be defined in the same order on both the
     master and the slave.

   * Any additional columns must be defined following the matching
     columns.

In addition, when the slave's copy of the table has more columns than
the master's copy, then each matching column must use the same data
type.

Examples

The following examples illustrate some valid and invalid table
definitions:

   * More columns on the master

     The following table definitions are valid:

          master> CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);
          slave>  CREATE TABLE t1 (c1 INT, c2 INT);

     The following table definitions would raise Error 1532
     (ER_BINLOG_ROW_RBR_TO_SBR) because the definitions of the columns
     common to both versions of the table are in a different order on
     the slave than they are on the master:

          master> CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);
          slave>  CREATE TABLE t1 (c2 INT, c1 INT);

     The following table definitions would also raise Error 1532,
     because the definition of the extra column on the master appears
     before the definitions of the columns common to both versions of
     the table:

          master> CREATE TABLE t1 (c3 INT, c1 INT, c2 INT);
          slave>  CREATE TABLE t1 (c1 INT, c2 INT);

   * More columns on the slave

     The following definitions replicate correctly:

          master> CREATE TABLE t1 (c1 INT, c2 INT);
          slave>  CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);

     The following definitions raise Error 1532 because the columns
     common to both versions of the table are not defined in the same
     order on both the master and the slave:

          master> CREATE TABLE t1 (c1 INT, c2 INT);
          slave>  CREATE TABLE t1 (c2 INT, c1 INT, c3 INT);

     The following table definitions also raise Error 1532 because the
     definition for the extra column in the slave's version of the
     table appears before the definitions for the columns which are
     common to both versions of the table:

          master> CREATE TABLE t1 (c1 INT, c2 INT);
          slave>  CREATE TABLE t1 (c3 INT, c1 INT, c2 INT);

     The following table definitions fail, because the slave's version
     of the table has additional columns compared to the master's
     version, and the two versions of the table define column `c2' as a
     different data type.

          master> CREATE TABLE t1 (c1 INT, c2 BIGINT);
          slave>  CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);


File: manual.info,  Node: replication-features-different-data-types,  Prev: replication-features-more-columns,  Up: replication-features-differing-tables

16.3.1.6 Replication of Columns Having Different Data Types
...........................................................

Corresponding columns on the master's and the slave's copies of the
same table should have the same type. However, this is not always
strictly enforced, as long as certain conditions are met. These
conditions are listed here:

   * The slave's copy of the table cannot contain more columns than the
     master's copy.

   * For columns holding numeric data types, the sizes may differ, as
     long as the size of the slave's version of the column is equal or
     greater to the size of the master's version of the column. This is
     sometimes referred to as _attribute promotion_, because the data
     type of the master's version of the column is promoted to a type
     that is the same size or larger on the slave.

     Data type conversions currently supported by attribute promotion
     are shown in the following table, in which X and N both represent
     positive integers.

     Original Data Type                 Promoted Data Type(s)
     `CHAR(X)'                          `CHAR(X+N)'
     `VARCHAR(X)'                       `VARCHAR(X+N)'
     `CHAR(X)'                          `VARCHAR(X+N)'
     `BINARY(X)'                        `BINARY(X+N)'
     `VARBINARY(X)'                     `VARBINARY(X+N)'
     `BINARY(X)'                        `VARBINARY(X+N)'
     `BIT(X) '                          `BIT(X+N)'
     *Note `TINYINT': numeric-types.    *Note `SMALLINT': numeric-types,
                                        *Note `MEDIUMINT': numeric-types,
                                        *Note `INT': numeric-types, or
                                        *Note `BIGINT': numeric-types.
     *Note `SMALLINT': numeric-types.   *Note `MEDIUMINT': numeric-types,
                                        *Note `INT': numeric-types, or
                                        *Note `BIGINT': numeric-types.
     *Note `MEDIUMINT': numeric-types.  *Note `INT': numeric-types. or
                                        *Note `BIGINT': numeric-types.
     *Note `INT': numeric-types.        *Note `BIGINT': numeric-types.

     Unsigned integer columns can be promoted to larger unsigned types;
     for example, a column declared as `TINYINT UNSIGNED' can be
     restored to a column declared as `SMALLINT UNSIGNED', `MEDIUMINT
     UNSIGNED', `INT UNSIGNED', or `BIGINT UNSIGNED'. You cannot
     promote a signed column to an unsigned type, or an unsigned column
     to a signed type.

     For columns holding numeric data types the sizes may differ, as
     long as the size of the slave's version of the column is equal or
     greater to the size of the master's version of the column. For
     example, the following table definitions are allowed:

          master> CREATE TABLE t1 (c1 TINYINT, c2 INT);
          slave>  CREATE TABLE t1 (c1 INT,     c2 INT);

     The slave's versions of both columns `c1' and `c2' are the same
     size as or larger than the master's versions of these columns.
     However, the following definitions would fail:

          master> CREATE TABLE t1 (c1 INT, c2 FLOAT(8,3));
          slave>  CREATE TABLE t1 (c1 INT, c2 FLOAT(7,3));

     In this case, Error 1532 would be raised because the master's copy
     of column `c2' is larger than its counterpart on the slave -- that
     is, the master's copy of `c2' on the master can hold more digits
     than the slave's copy of the column.

   * There is no conversion between integer (*Note `TINYINT':
     numeric-types, *Note `SMALLINT': numeric-types, *Note `MEDIUMINT':
     numeric-types, and so on) and non-integer (*Note `FLOAT':
     numeric-types, *Note `DOUBLE': numeric-types, *Note `DECIMAL':
     numeric-types, and so on) numeric data types, and so the following
     definitions would fail with Error 1532:

          master> CREATE TABLE t1 (c1 INT, c2 FLOAT(8,3));
          slave>  CREATE TABLE t1 (c1 INT, c2 BIGINT);

     A column using a non-integer numeric data type must always have
     the same definition on both the master and the slave.

   * For columns storing *Note `CHAR': char.  and *Note `BINARY':
     binary-varbinary. data, the size of the slave's copy of the column
     must be equal to or greater than the size of the master's copy. For
     example, the following table definitions would replicate
     successfully:

          master> CREATE TABLE t1 (c1 INT, c2 CHAR(30));
          slave>  CREATE TABLE t1 (c1 INT, c2 CHAR(50));

     If the size of the master's version of the column is greater than
     that of the slave's version of the column, replication fails with
     Error 1532.

   * The replication process can convert freely between *Note `BINARY':
     binary-varbinary, *Note `VARBINARY': binary-varbinary, *Note
     `CHAR': char. and *Note `VARCHAR': char. columns, as long as the
     slave's version of the column is the same size as or larger than
     the master's version. For example, the following table definitions
     can be used successfully:

          master> CREATE TABLE t1 (c1 INT, c2 VARBINARY(30));
          slave>  CREATE TABLE t1 (c1 INT, c2 CHAR(30));

     *Note*:

     Since replication is currently not supported between different
     character sets, it is sufficient when comparing sizes of columns
     containing character data to count the number of characters rather
     than the number of bytes.

   * Attribute promotion can be used with both statement-based and
     row-based replication, and is not dependent on the storage engine
     used by either the master or the slave.


File: manual.info,  Node: replication-features-directory,  Next: replication-features-drop-if-exists,  Prev: replication-features-differing-tables,  Up: replication-features

16.3.1.7 Replication and `DIRECTORY' Table Options
..................................................

If a `DATA DIRECTORY' or `INDEX DIRECTORY' table option is used in a
*Note `CREATE TABLE': create-table. statement on the master server, the
table option is also used on the slave. This can cause problems if no
corresponding directory exists in the slave host file system or if it
exists but is not accessible to the slave server. This can be
overridden by using the `NO_DIR_IN_CREATE' server SQL mode on the
slave, which causes the slave to ignore the `DATA DIRECTORY' and `INDEX
DIRECTORY' table options when replicating *Note `CREATE TABLE':
create-table. statements. The result is that `MyISAM' data and index
files are created in the table's database directory.

For more information, see *Note server-sql-mode::.


File: manual.info,  Node: replication-features-drop-if-exists,  Next: replication-features-invoked,  Prev: replication-features-directory,  Up: replication-features

16.3.1.8 Replication of `DROP ... IF EXISTS' Statements
.......................................................

The statements *Note `DROP DATABASE IF EXISTS': drop-database, *Note
`DROP TABLE IF EXISTS': drop-table, and *Note `DROP VIEW IF EXISTS':
drop-view. are always replicated, even if the database, table, or view
to be dropped does not exist on the master. This is to ensure that the
object to be dropped no longer exists on either the master or the
slave, once the slave has caught up with the master.

Beginning with MySQL 6.0.10, the statements *Note `DROP PROCEDURE IF
EXISTS': drop-procedure. and *Note `DROP FUNCTION IF EXISTS':
drop-function. are also replicated, even if the procedure or function
to be dropped does not exist on the master. (Bug#13684
(http://bugs.mysql.com/13684))


File: manual.info,  Node: replication-features-invoked,  Next: replication-features-floatvalues,  Prev: replication-features-drop-if-exists,  Up: replication-features

16.3.1.9 Replication of Invoked Features
........................................

Replication of invoked features such as scheduled events, user-defined
functions (UDFs), stored routines (including both stored procedures and
stored functions), and triggers provide the following characteristics:

   * The effects of the feature are always replicated.

   * The following statements are replicated using statement-based
     replication:

        * *Note `CREATE EVENT': create-event.

        * *Note `ALTER EVENT': alter-event.

        * *Note `DROP EVENT': drop-event.

        * *Note `CREATE PROCEDURE': create-procedure.

        * *Note `DROP PROCEDURE': drop-procedure.

        * *Note `CREATE FUNCTION': create-function.

        * *Note `DROP FUNCTION': drop-function.

        * *Note `CREATE TRIGGER': create-trigger.

        * *Note `DROP TRIGGER': drop-trigger.

     However, the _effects_ of features created, modified, or dropped
     using these statements are replicated using row-based replication.

     *Note*:

     Attempting to replicate invoked features using statement-based
     replication produces the warning `Statement is not safe to log in
     statement format'. For example, trying to replicate a UDF with
     statement-based replication generates this warning because it
     currently cannot be determined by the MySQL server whether the UDF
     is deterministic. If you are absolutely certain that the invoked
     feature's effects are deterministic, you can safely disregard such
     warnings.

     In a future MySQL release, we may implement ways for users to
     indicate that such features are deterministic, so that they can be
     recognized by the server as `safe' for statement-based replication.
     (Bug#34597 (http://bugs.mysql.com/34597))

   * In the case of *Note `CREATE EVENT': create-event.  and *Note
     `ALTER EVENT': alter-event.:

        * The status of the event is set to `SLAVESIDE_DISABLED' on the
          slave regardless of the state specified (this does not apply
          to *Note `DROP EVENT': drop-event.).

        * The master on which the event was created is identified on
          the slave by its server ID. The `ORIGINATOR' column in *Note
          `INFORMATION_SCHEMA.EVENTS': events-table.  and the
          `originator' column in `mysql.event' store this information.
          (See *Note events-table::, and *Note show-events::.)

   * The feature implementation resides on the slave in a renewable
     state so that if the master fails, the slave can be used as the
     master without loss of event processing.

To determine whether there are any scheduled events on a MySQL server
that were created on a different server (that was acting as a
replication master), use *Note `SHOW EVENTS': show-events, like this:

     SHOW EVENTS
         WHERE STATUS = 'SLAVESIDE_DISABLED';

Alternatively, you might wish to query the *Note
`INFORMATION_SCHEMA.EVENTS': events-table. table as shown here:

     SELECT EVENT_SCHEMA, EVENT_NAME, ORIGINATOR
         FROM INFORMATION_SCHEMA.EVENTS
         WHERE STATUS = 'SLAVESIDE_DISABLED';

When promoting a replication slave having such events to a replication
master, use the following query to enable the events:

     UPDATE mysql.event
         SET STATUS = 'ENABLED'
         WHERE STATUS = 'SLAVESIDE_DISABLED';

If more than one master was involved in creating events on this slave,
and you wish to enable events that were created only on a given master
having the server ID MASTER_ID, use the following query instead:

     UPDATE mysql.event
         SET STATUS = 'ENABLED'
         WHERE ORIGINATOR = MASTER_ID
         AND STATUS = 'SLAVESIDE_DISABLED';

*Important*:

Before executing either of the previous two *Note `UPDATE': update.
statements, you should disable the Event Scheduler on the slave (using
`SET GLOBAL EVENT_SCHEDULER = OFF;'), run the *Note `UPDATE': update,
restart the server, then re-enable the Event Scheduler afterwards (using
`SET GLOBAL EVENT_SCHEDULER = ON;').

If you later demote the new master back to being a replication slave,
you must disable manually all events enabled by the *Note `UPDATE':
update. statement. You can do this by storing in a separate table the
event names from the *Note `SELECT': select. statement shown
previously, or using an *Note `UPDATE': update.  statement to rename
the events with a common prefix to identify them, as shown in this
example:

     UPDATE mysql.event
         SET name = CONCAT('replicated_', name)
         WHERE status = 'SLAVESIDE_DISABLED';

When demoting this server back to being a replication slave, you can
then rename and disable the events like this:

     UPDATE mysql.event
         SET name = REPLACE(name, 'replicated_', ''),
             status = 'SLAVESIDE_DISABLED'
         WHERE INSTR(name, 'replicated_') = 1;


File: manual.info,  Node: replication-features-floatvalues,  Next: replication-features-flush,  Prev: replication-features-invoked,  Up: replication-features

16.3.1.10 Replication with Floating-Point Values
................................................

With statement-based replication, values are converted from decimal to
binary. Because conversions between decimal and binary representations
of them may be approximate, comparisons involving floating-point values
are inexact. This is true for operations that use floating-point values
explicitly, or that use values that are converted to floating-point
implicitly.  Comparisons of floating-point values might yield different
results on master and slave servers due to differences in computer
architecture, the compiler used to build MySQL, and so forth. See *Note
type-conversion::, and *Note problems-with-float::.


File: manual.info,  Node: replication-features-flush,  Next: replication-features-functions,  Prev: replication-features-floatvalues,  Up: replication-features

16.3.1.11 Replication and `FLUSH'
.................................

Some forms of the *Note `FLUSH': flush. statement are not logged
because they could cause problems if replicated to a slave: *Note
`FLUSH LOGS': flush, *Note `FLUSH MASTER': flush, *Note `FLUSH SLAVE':
flush, and *Note `FLUSH TABLES WITH READ LOCK': flush. For a syntax
example, see *Note flush::. The *Note `FLUSH TABLES': flush, *Note
`ANALYZE TABLE': analyze-table, *Note `OPTIMIZE TABLE': optimize-table,
and *Note `REPAIR TABLE': repair-table. statements are written to the
binary log and thus replicated to slaves. This is not normally a
problem because these statements do not modify table data.

However, this behavior can cause difficulties under certain
circumstances. If you replicate the privilege tables in the `mysql'
database and update those tables directly without using *Note `GRANT':
grant, you must issue a *Note `FLUSH PRIVILEGES': flush. on the slaves
to put the new privileges into effect. In addition, if you use *Note
`FLUSH TABLES': flush.  when renaming a `MyISAM' table that is part of
a `MERGE' table, you must issue *Note `FLUSH TABLES': flush.  manually
on the slaves. These statements are written to the binary log unless
you specify `NO_WRITE_TO_BINLOG' or its alias `LOCAL'.


File: manual.info,  Node: replication-features-functions,  Next: replication-features-limit,  Prev: replication-features-flush,  Up: replication-features

16.3.1.12 Replication and System Functions
..........................................

Certain functions do not replicate well under some conditions:

   * The `USER()', `CURRENT_USER()', `UUID()', `VERSION()', and
     `LOAD_FILE()' functions are replicated without change and thus do
     not work reliably on the slave unless row-based replication is
     enabled. This is also true for `CURRENT_USER'.  (See *Note
     replication-formats::.)

     Beginning with MySQL 6.0.4, `USER()', `CURRENT_USER()', and
     `CURRENT_USER' are automatically replicated using row-based
     replication when using `MIXED' mode, and generate a warning in
     `STATEMENT' mode. (Bug#28086 (http://bugs.mysql.com/28086))

   * For `NOW()', the binary log includes the timestamp and replicates
     correctly.

     Unlike `NOW()', the `SYSDATE()' function is not replication-safe
     because it is not affected by `SET TIMESTAMP' statements in the
     binary log and is non-deterministic if statement-based logging is
     used. This is not a problem if row-based logging is used. Another
     option is to start the server with the `--sysdate-is-now' option to
     cause `SYSDATE()' to be an alias for `NOW()'.

   * _The following restriction applies to statement-based replication
     only, not to row-based replication._ The `GET_LOCK()',
     `RELEASE_LOCK()', `IS_FREE_LOCK()', and `IS_USED_LOCK()' functions
     that handle user-level locks are replicated without the slave
     knowing the concurrency context on master. Therefore, these
     functions should not be used to insert into a master's table
     because the content on the slave would differ. (For example, do
     not issue a statement such as `INSERT INTO mytable
     VALUES(GET_LOCK(...))'.)

As a workaround for the preceding limitations when statement-based
replication is in effect, you can use the strategy of saving the
problematic function result in a user variable and referring to the
variable in a later statement. For example, the following single-row
*Note `INSERT': insert. is problematic due to the reference to the
`UUID()' function:

     INSERT INTO t VALUES(UUID());

To work around the problem, do this instead:

     SET @my_uuid = UUID();
     INSERT INTO t VALUES(@my_uuid);

That sequence of statements replicates because the value of `@my_uuid'
is stored in the binary log as a user-variable event prior to the *Note
`INSERT': insert. statement and is available for use in the *Note
`INSERT': insert.

The same idea applies to multiple-row inserts, but is more cumbersome
to use. For a two-row insert, you can do this:

     SET @my_uuid1 = UUID(); @my_uuid2 = UUID();
     INSERT INTO t VALUES(@my_uuid1),(@my_uuid2);

However, if the number of rows is large or unknown, the workaround is
difficult or impracticable. For example, you cannot convert the
following statement to one in which a given individual user variable is
associated with each row:

     INSERT INTO t2 SELECT UUID(), * FROM t1;

Within a stored function, `RAND()' replicates correctly as long as it
is invoked only once during the execution of the function. (You can
consider the function execution timestamp and random number seed as
implicit inputs that are identical on the master and slave.)

The `FOUND_ROWS()' and `ROW_COUNT()' functions are not replicated
reliably using statement-based replication. A workaround is to store
the result of the function call in a user variable, and then use that
in the *Note `INSERT': insert. statement. For example, if you wish to
store the result in a table named `mytable', you might normally do so
like this:

     SELECT SQL_CALC_FOUND_ROWS FROM mytable LIMIT 1;
     INSERT INTO mytable VALUES( FOUND_ROWS() );

However, if you are replicating `mytable', then you should use `SELECT
INTO', and then store the variable in the table, like this:

     SELECT SQL_CALC_FOUND_ROWS INTO @found_rows FROM mytable LIMIT 1;
     INSERT INTO mytable VALUES(@found_rows);

In this way, the user variable is replicated as part of the context,
and applied on the slave correctly.

Beginning with MySQL 6.0.4, these functions are automatically
replicated using row-based replication when using `MIXED' mode, and
generate a warning in `STATEMENT' mode. (Bug#12092
(http://bugs.mysql.com/12092), Bug#30244 (http://bugs.mysql.com/30244))


File: manual.info,  Node: replication-features-limit,  Next: replication-features-load-data,  Prev: replication-features-functions,  Up: replication-features

16.3.1.13 Replication and `LIMIT'
.................................

Statement-based replication of `LIMIT' clauses in *Note `DELETE':
delete, *Note `UPDATE': update, and *Note `INSERT ... SELECT':
insert-select. statements is unsafe since the order of the rows
affected is not defined. (Such statements can be replicated correctly
when using `STATEMENT' mode only if they also contain an `ORDER BY'
clause.)  Beginning with MySQL 6.0.5, when such a statement (without
`ORDER BY') is encountered:

   * When using `STATEMENT' mode, a warning that the statement is not
     safe for statement-based replication is now issued.

     Currently, when using `STATEMENT' mode, warnings are issued for
     DML statements containing `LIMIT' even when they also have an
     `ORDER BY' clause (and so are made deterministic). This is a known
     issue which we are working to resolve in a future MySQL release.
     (Bug#42851 (http://bugs.mysql.com/42851))

   * When using `MIXED' mode, the statement is now automatically
     replicated using row-based mode.


File: manual.info,  Node: replication-features-load-data,  Next: replication-features-logging,  Prev: replication-features-limit,  Up: replication-features

16.3.1.14 Replication and `LOAD DATA'
.....................................

The *Note `LOAD DATA': load-data. statement is not replicated correctly
to a slave running MySQL 5.1 or later from a master running MySQL 4.0
or earlier.

When using statement-based replication, the *Note `LOAD DATA INFILE':
load-data. statement's `CONCURRENT' option is not replicated; that is,
`LOAD DATA CONCURRENT INFILE' is replicated as *Note `LOAD DATA
INFILE': load-data, and `LOAD DATA CONCURRENT LOCAL INFILE' is
replicated as *Note `LOAD DATA LOCAL INFILE': load-data. The
`CONCURRENT' option _is_ replicated when using row-based replication.
(Bug#34628 (http://bugs.mysql.com/34628))


File: manual.info,  Node: replication-features-logging,  Next: replication-features-mastercrash,  Prev: replication-features-load-data,  Up: replication-features

16.3.1.15 Replication and the Slow Query Log
............................................

Prior to MySQL 6.0.11, replication slaves did not write replicated
queries to the slow query log, even if the same queries were written to
the slow query log on the master. (Bug#23300
(http://bugs.mysql.com/23300))


File: manual.info,  Node: replication-features-mastercrash,  Next: replication-features-mastershutdown,  Prev: replication-features-logging,  Up: replication-features

16.3.1.16 Replication During a Master Crash
...........................................

A crash on the master side can result in the master's binary log having
a final position less than the most recent position read by the slave,
due to the master's binary log file not being flushed. This can cause
the slave not to be able to replicate when the master comes back up.
Setting `sync_binlog=1' in the master `my.cnf' file helps to minimize
this problem because it causes the master to flush its binary log more
frequently.


File: manual.info,  Node: replication-features-mastershutdown,  Next: replication-features-memory,  Prev: replication-features-mastercrash,  Up: replication-features

16.3.1.17 Replication During a Master Shutdown
..............................................

It is safe to shut down a master server and restart it later.  When a
slave loses its connection to the master, the slave tries to reconnect
immediately and retries periodically if that fails.  The default is to
retry every 60 seconds. This may be changed with the *Note `CHANGE
MASTER TO': change-master-to.  statement. A slave also is able to deal
with network connectivity outages. However, the slave notices the
network outage only after receiving no data from the master for
`slave_net_timeout'
(http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_net_timeout)
seconds. If your outages are short, you may want to decrease
`slave_net_timeout'
(http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_net_timeout).
See *Note server-system-variables::.


File: manual.info,  Node: replication-features-memory,  Next: replication-features-mysqldb,  Prev: replication-features-mastershutdown,  Up: replication-features

16.3.1.18 Replication with `MEMORY' Tables
..........................................

When a server shuts down and restarts, its `MEMORY' tables become
empty. The master replicates this effect to slaves as follows: The
first time that the master uses each `MEMORY' table after startup, it
logs an event that notifies the slaves that the table needs to be
emptied by writing a *Note `DELETE': delete. statement for that table
to the binary log. See *Note memory-storage-engine::, for more
information about `MEMORY' tables.


File: manual.info,  Node: replication-features-mysqldb,  Next: replication-features-optimizer,  Prev: replication-features-memory,  Up: replication-features

16.3.1.19 Replication of the System `mysql' Database
....................................................

Data modification statements made to tables in the `mysql' database are
replicated according to the value of `binlog_format'; if this value is
`MIXED', then these statement are replicated using the row-based
format. However, statements that would normally update this information
indirectly -- such *Note `GRANT': grant, *Note `REVOKE': revoke, and
statements manipulating triggers, stored routines, and views -- are
replicated to slaves using statement-based replication.


File: manual.info,  Node: replication-features-optimizer,  Next: replication-features-reserved-words,  Prev: replication-features-mysqldb,  Up: replication-features

16.3.1.20 Replication and the Query Optimizer
.............................................

It is possible for the data on the master and slave to become different
if a statement is designed in such a way that the data modification is
non-deterministic; that is, left up the query optimizer. (This is in
general not a good practice, even outside of replication.) Examples of
non-deterministic statements include *Note `DELETE': delete. or *Note
`UPDATE': update. statements that use `LIMIT' with no `ORDER BY'
clause; see *Note replication-features-limit::, for a detailed
discussion of these.


File: manual.info,  Node: replication-features-reserved-words,  Next: replication-features-slaveerrors,  Prev: replication-features-optimizer,  Up: replication-features

16.3.1.21 Replication and Reserved Words
........................................

You can encounter problems when you are attempting to replicate from an
older master to a newer slave and you make use of identifiers on the
master that are reserved words in the newer MySQL version running on
the slave. An example of this is using a table column named
`current_user' on a 4.0 master that is replicating to a 4.1 or higher
slave, because `CURRENT_USER' is a reserved word beginning in MySQL
4.1. Replication can fail in such cases with Error 1064 `You have an
error in your SQL syntax...', _even if a database or table named using
the reserved word or a table having a column named using the reserved
word is excluded from replication_. This is due to the fact that each
SQL statement must be parsed by the slave prior to execution, so that
the slave knows which database object or objects would be effected by
the statement; only after the statement is parsed can the slave apply
any filtering rules defined by `--replicate-do-db',
`--replicate-do-table', `--replicate-ignore-db', and
`--replicate-ignore-table'.

To work around the problem of database, table, or column names on the
master which would be regarded as reserved words by the slave, do one
of the following:

   * Use one or more *Note `ALTER TABLE': alter-table.  statements on
     the master to change the names of any database objects where these
     names would be considered reserved words on the slave, and change
     any SQL statements that use the old names to use the new names
     instead.

   * In any SQL statements using these database object names, set the
     names off using backtick characters (``').

For listings of reserved words by MySQL version, see Reserved Words
(http://dev.mysql.com/doc/mysqld-version-reference/en/mysqld-version-reference-optvar.html),
in the `MySQL Server Version Reference'.


File: manual.info,  Node: replication-features-slaveerrors,  Next: replication-features-slaveshutdown,  Prev: replication-features-reserved-words,  Up: replication-features

16.3.1.22 Slave Errors during Replication
.........................................

If a statement on a slave produces an error, the slave SQL thread
terminates, and the slave writes a message to its error log. You should
then connect to the slave manually and determine the cause of the
problem. (*Note `SHOW SLAVE STATUS': show-slave-status. is useful for
this.) Then fix the problem (for example, you might need to create a
non-existent table) and run *Note `START SLAVE': start-slave.

MySQL Enterprise

For instant notification when a slave thread terminates subscribe to
the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: replication-features-slaveshutdown,  Next: replication-features-temptables,  Prev: replication-features-slaveerrors,  Up: replication-features

16.3.1.23 Replication during a Slave Shutdown
.............................................

Shutting down the slave (cleanly) is also safe because it keeps track
of where it left off. Unclean shutdowns might produce problems,
especially if the disk cache was not flushed to disk before the system
went down. Your system fault tolerance is greatly increased if you have
a good uninterruptible power supply. Unclean shutdowns of the master
may cause inconsistencies between the content of tables and the binary
log in master.


File: manual.info,  Node: replication-features-temptables,  Next: replication-features-timeout,  Prev: replication-features-slaveshutdown,  Up: replication-features

16.3.1.24 Replication and Temporary Tables
..........................................

This item does not apply when row-based replication is in use because
in that case temporary tables are not replicated (see *Note
replication-formats::).

Safe shutdown of slaves when using temporary tables

Temporary tables are replicated except in the case where you shut down
the slave server (not just the slave threads) and you have replicated
temporary tables that are used in updates that have not yet been
executed on the slave. If you shut down the slave server, the temporary
tables needed by those updates are no longer available when the slave
is restarted. To avoid this problem, do not shut down the slave while
it has temporary tables open. Instead, use the following procedure:

  1. Issue a `STOP SLAVE SQL_THREAD' statement.

  2. Use *Note `SHOW STATUS': show-status. to check the value of the
     `Slave_open_temp_tables' variable.

  3. If the value is 0, issue a *Note `mysqladmin shutdown':
     mysqladmin. command to stop the slave.

  4. If the value is not 0, restart the slave SQL thread with `START
     SLAVE SQL_THREAD'.

  5. Repeat the procedure later until the `Slave_open_temp_tables'
     variable is 0 and you can stop the slave.

Temporary tables and replication options

By default, all temporary tables are replicated; this happens whether
or not there are any matching `--replicate-do-db',
`--replicate-do-table', or `--replicate-wild-do-table' options in
effect. However, the `--replicate-ignore-table' and
`--replicate-wild-ignore-table' options are honored for temporary
tables.

A recommended practice when using statement-based or mixed-format
replication is to designate a prefix for exclusive use in naming
temporary tables that you do not want replicated, then employ a matching
`--replicate-wild-ignore-table' option. For example, you might give all
such tables names beginning with `norep_' (such as `norep_tablea',
`norep_tableb', and so on), then use
`--replicate-wild-ignore-table=norep_' to prevent the replication of
these tables.


File: manual.info,  Node: replication-features-timeout,  Next: replication-features-timezone,  Prev: replication-features-temptables,  Up: replication-features

16.3.1.25 Replication Retries and Timeouts
..........................................

The global system variable `slave_transaction_retries'
(http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_transaction_retries)
affects replication as follows: If the replication slave SQL thread
fails to execute a transaction because of an `InnoDB' deadlock or
because it exceeded the `InnoDB' `innodb_lock_wait_timeout' value, the
transaction is automatically retried `slave_transaction_retries'
(http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_transaction_retries)
times before stopping with an error. The default value is 10. The total
retry count can be seen in the output of *Note `SHOW STATUS':
show-status.; see *Note server-status-variables::.


File: manual.info,  Node: replication-features-timezone,  Next: replication-features-transactions,  Prev: replication-features-timeout,  Up: replication-features

16.3.1.26 Replication and Time Zones
....................................

If the master uses MySQL 4.1, the same system time zone should be set
for both master and slave. Otherwise some statements will not be
replicated properly, such as statements that use the `NOW()' or
`FROM_UNIXTIME()' functions. You can set the time zone in which MySQL
server runs by using the `--timezone=TIMEZONE_NAME' option of the
`mysqld_safe' script or by setting the `TZ' environment variable. Both
master and slave should also have the same default connection time zone
setting; that is, the `--default-time-zone' parameter should have the
same value for both master and slave. Note that this is not necessary
when the master is MySQL 5.0 or later.

`CONVERT_TZ(...,...,@@session.time_zone)' is properly replicated only
if both master and slave are running MySQL 5.0.4 or newer.


File: manual.info,  Node: replication-features-transactions,  Next: replication-features-triggers,  Prev: replication-features-timezone,  Up: replication-features

16.3.1.27 Replication and Transactions
......................................

It is possible to replicate transactional tables on the master using
non-transactional tables on the slave. For example, you can replicate
an `InnoDB' master table as a `MyISAM' slave table. However, if you do
this, there are problems if the slave is stopped in the middle of a
*Note `BEGIN': commit./*Note `COMMIT': commit.  block because the slave
restarts at the beginning of the *Note `BEGIN': commit. block.

Beginning with MySQL 6.0.10, it is also safe to replicate transactions
from `MyISAM' tables on the master to transactional tables -- such as
tables that use the `InnoDB' storage engine -- on the slave. In such
cases (beginning with MySQL 6.0.10), an `AUTOCOMMIT=1' statement issued
on the master is replicated, thus enforcing `AUTOCOMMIT' mode on the
slave.

Mixing transactional and non-transactional statements within the same
transaction

The semantics of mixing non-transactional and transactional tables in a
transaction in the first statement of a transaction changed in MySQL
6.0.10. Previously, if the first statement in a transaction contained
non-transactional changes, the statement was written directly to the
binary log, in an attempt to mimic the non-transactional behavior of the
statement. Beginning with MySQL 6.0.10, any statement appearing after a
*Note `BEGIN': commit. is always considered part of the transaction and
cached. This means that non-transactional changes do not propagate to
the slave until the transaction is committed and thus written to the
binary log. In addition (also beginning with MySQL 5.1.31), if
`AUTOMCOMMIT' is set to 0, any statement appearing immediately
following a *Note `COMMIT': commit. is handled in the same way.

Previously, a statement was considered non-transactional if it changed
a non-transactional table. This behavior had the following subtle but
non-trivial consequences:

   * A statement containing only non-transactional changes was written
     immediately to the binary log (sometime referred to as
     `write-ahead').

   * A statement containing only transactional changes was always
     cached while waiting for the transaction to be committed.

   * A statement containing a mix of transactional and
     non-transactional changes (that is, a statement updating both
     transaction and non-transactional tables) could lead to mismatched
     tables on the master and the slave.

In situations where transactions mix updates to transactional and
non-transactional tables, the order of statements in the binary log is
correct, and all needed statements are written to the binary log even
in case of a *Note `ROLLBACK': commit.  However, when a second
connection updates the non-transactional table before the first
connection's transaction is complete, statements can be logged out of
order, because the second connection's update is written immediately
after it is performed, regardless of the state of the transaction being
performed by the first connection.

Due to the non-transactional nature of `MyISAM' tables, it is possible
to have a statement that only partially updates a table and returns an
error code. This can happen, for example, on a multiple-row insert that
has one row violating a key constraint, or if a long update statement
is killed after updating some of the rows. If that happens on the
master, the slave thread exits and waits for the database administrator
to decide what to do about it unless the error code is legitimate and
execution of the statement results in the same error code on the slave.
If this error code validation behavior is not desirable, some or all
errors can be masked out (ignored) with the `--slave-skip-errors'
option.

*Caution*:

You should avoid transactions that update both transactional and
non-transactional tables in a replication environment.

When the storage engine type of the slave is non-transactional,
transactions on the master that mix updates of transactional and
non-transactional tables should be avoided because they can cause
inconsistency of the data between the master's transactional table and
the slave's non-transactional table.  That is, such transactions can
lead to master storage engine-specific behavior with the possible
effect of replication going out of synchrony. MySQL does not issue a
warning about this currently, so extra care should be taken when
replicating transactional tables from the master to non-transactional
ones on the slaves.


File: manual.info,  Node: replication-features-triggers,  Next: replication-features-truncate,  Prev: replication-features-transactions,  Up: replication-features

16.3.1.28 Replication and Triggers
..................................

Triggers are not executed on the slave under row-based replication.
However they are are executed on the slave under statement-based
replication. Instead, when using row-based replication, the changes
caused by executing the trigger on the master are applied on the slave.

This behavior is by design. The reason for this is that, if both the
master and the slave applied the changes from the master and, in
addition, the trigger causing these changes were applied on the slave,
the changes would in effect be applied twice on the slave, leading to
different data on the master and the slave.

If you wish for triggers to execute on both the master and the slave --
perhaps because you have different triggers on the master and slave --
then you must use statement-based replication. However, it is not
necessary to use statement-based replication exclusively if you want to
enable slave-side triggers; it is sufficient in such cases to switch to
statement-based replication only for those statements where you want
this effect, and to use row-based replication the rest of the time.

Before MySQL 6.0.10, a trigger that was defined on a transactional
table but that updated a non-transactional tables could cause updates
on the transactional table to be replicated before they were actually
committed on the master, and not be rolled back correctly on the slave
if they were rolled back on the master. (Bug#40116
(http://bugs.mysql.com/40116)) See also *Note
replication-features-transactions::.


File: manual.info,  Node: replication-features-truncate,  Next: replication-features-variables,  Prev: replication-features-triggers,  Up: replication-features

16.3.1.29 Replication and `TRUNCATE'
....................................

*Note `TRUNCATE': truncate. is normally regarded as a DML statement,
and so would be expected to be logged and replicated using row-based
format when the binary logging mode is `ROW' or `MIXED'. However this
caused issues when logging or replicating, in `STATEMENT' or `MIXED'
mode, tables that used transactional storage engines such as `InnoDB'
when the transaction isolation level was `READ COMMITTED' or `READ
UNCOMMITTED', which precludes statement-based logging.

Beginning with MySQL 6.0.10, *Note `TRUNCATE': truncate. is treated for
purposes of logging and replication as DDL rather than DML so that it
can be logged and replicated as a statement. However, the effects of
the statement as applicable to `InnoDB' and other transactional tables
on replication slaves still follow the rules described in *Note
truncate:: governing such tables. (Bug#36763
(http://bugs.mysql.com/36763))


File: manual.info,  Node: replication-features-variables,  Next: replication-features-views,  Prev: replication-features-truncate,  Up: replication-features

16.3.1.30 Replication and Variables
...................................

The `foreign_key_checks', `unique_checks', and `sql_auto_is_null'
variables are all replicated.

`sql_mode' is also replicated except for the `NO_DIR_IN_CREATE' mode.
However, when *Note `mysqlbinlog': mysqlbinlog. parses a `SET
@@sql_mode = VALUE' statement, the full VALUE, including
`NO_DIR_IN_CREATE', is passed to the receiving server.

The `storage_engine' system variable is not replicated, which is a good
thing for replication between different storage engines.

Session variables are not replicated properly when used in statements
that update tables. For example, `SET MAX_JOIN_SIZE=1000' followed by
`INSERT INTO mytable VALUES(@@MAX_JOIN_SIZE)' will not insert the same
data on the master and the slave. This does not apply to the common
sequence of `SET TIME_ZONE=...' followed by `INSERT INTO mytable
VALUES(CONVERT_TZ(...,...,@@time_zone))'.

Replication of session variables is not a problem when row-based
replication is being used. See *Note replication-formats::.


File: manual.info,  Node: replication-features-views,  Prev: replication-features-variables,  Up: replication-features

16.3.1.31 Replication and Views
...............................

Views are always replicated to slaves. Views are filtered by their own
name, not by the tables they refer to. This means that a view can be
replicated to the slave even if the view contains a table that would
normally be filtered out by `replication-ignore-table' rules. Care
should therefore be taken to ensure that views do not replicate table
data that would normally be filtered for security reasons.


File: manual.info,  Node: replication-compatibility,  Next: replication-upgrade,  Prev: replication-features,  Up: replication-notes

16.3.2 Replication Compatibility Between MySQL Versions
-------------------------------------------------------

MySQL supports replication from one major version to the next higher
major version. For example, you can replicate from a master running
MySQL 4.1 to a slave running MySQL 5.0, from a master running MySQL 5.0
to a slave running MySQL 5.1, from a master running MySQL 5.1 to a
slave running MySQL 6.0, and so on.

In some cases, it is also possible to replicate between a master and a
slave that is more than one major version newer than the master.
However, there are known issues with trying to replicate from a master
running MySQL 4.1 or earlier to a slave running MySQL 5.1 or later. To
work around such problems, you can insert one or more MySQL servers
running intermediate versions between the two; for example, rather than
replicating directly from a MySQL 4.1 master to a MySQL 6.0 slave, it
is possible to replicate from a MySQL 4.1 server to a MySQL 5.0 server,
and then from the MySQL 5.0 server to a MySQL 5.1 server, and finally
from the MySQL 5.1 server to a MySQL 6.0 server.

*Important*:

We strongly recommend using the most recent release available within a
given MySQL major version because replication (and other) capabilities
are continually being improved. We also recommend upgrading masters and
slaves that use alpha or beta releases of a major version of MySQL to
GA (production) releases when these become available for that major
version.

Replication from newer masters to older slaves may be possible, but is
generally not supported. This is due to a number of factors:

   * Binary log format changes

     The binary log format can change between major releases.  While we
     attempt to maintain backwards compatiblity, this is not always
     possible. For example, the binary log format implemented in MySQL
     5.0 changed considerably from that used in previous versions,
     especially with regard to handling of character sets, *Note `LOAD
     DATA INFILE': load-data, and time zones. This means that
     replication from a MySQL 5.0 (or later) master to a MySQL 4.1 (or
     earlier) slave is generally not supported.

     This also has significant implications for upgrading replication
     servers; see *Note replication-upgrade::, for more information.

   * Use of row-based replication

     You cannot replicate using row-based replication from any MySQL
     6.0 or later master to a slave running MySQL 5.1.4 or earlier,
     since MySQL versions prior to 5.1.5 do not support RBR.

     For more information about row-based replication, see *Note
     replication-formats::.

   * SQL incompatiblities

     You cannot replicate from a newer master to an older slave using
     statement-based replication if the statements to be replicated use
     SQL features available on the master but not on the slave.

     However, if both the master and the slave support row-based
     replication, and there are no data definition statements to be
     replicated that depend on SQL features found on the master but not
     on the slave, then you can use row-based replication to replicate
     the effects of data modification statements even if the DDL run on
     the master is not supported on the slave.

For more information on potential replication issues, see *Note
replication-features::.


File: manual.info,  Node: replication-upgrade,  Next: replication-faq,  Prev: replication-compatibility,  Up: replication-notes

16.3.3 Upgrading a Replication Setup
------------------------------------

When you upgrade servers that participate in a replication setup, the
procedure for upgrading depends on the current server versions and the
version to which you are upgrading.

This section applies to upgrading replication from MySQL 3.23, 4.0, or
4.1 to MySQL 6.0. A 4.0 server should be 4.0.3 or newer.

When you upgrade a master to 6.0 from an earlier MySQL release series,
you should first ensure that all the slaves of this master are using
the same 6.0.x release. If this is not the case, you should first
upgrade the slaves. To upgrade each slave, shut it down, upgrade it to
the appropriate 6.0.x version, restart it, and restart replication.
The 6.0 slave is able to read the old relay logs written prior to the
upgrade and to execute the statements they contain. Relay logs created
by the slave after the upgrade are in 6.0 format.

After the slaves have been upgraded, shut down the master, upgrade it
to the same 6.0.x release as the slaves, and restart it. The 6.0 master
is able to read the old binary logs written prior to the upgrade and to
send them to the 6.0 slaves. The slaves recognize the old format and
handle it properly. Binary logs created by the master following the
upgrade are in 6.0 format. These too are recognized by the 6.0 slaves.

In other words, there are no measures to take when upgrading to MySQL
6.0, except that the slaves must be MySQL 6.0 before you can upgrade
the master to 6.0. Note that downgrading from 6.0 to older versions
does not work so simply: You must ensure that any 6.0 binary logs or
relay logs have been fully processed, so that you can remove them
before proceeding with the downgrade.

Downgrading a replication setup to a previous version cannot be done
once you have switched from statement-based to row-based replication,
and after the first row-based statement has been written to the binlog.
See *Note replication-formats::.


File: manual.info,  Node: replication-faq,  Next: replication-problems,  Prev: replication-upgrade,  Up: replication-notes

16.3.4 Replication FAQ
----------------------

MySQL Enterprise

For expert advice on replication subscribe to the MySQL Enterprise
Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Questions*
   * 16.3.4.1: Does the slave need to be connected to the master all the
     time?

   * 16.3.4.2: Do I have to enable networking on my master to enable
     replication?

   * 16.3.4.3: How do I know how late a slave is compared to the
     master? In other words, how do I know the date of the last
     statement replicated by the slave?

   * 16.3.4.4: How do I force the master to block updates until the
     slave catches up?

   * 16.3.4.5: What issues should I be aware of when setting up two-way
     replication?

   * 16.3.4.6: 

     How can I use replication to improve performance of my system?

   * 16.3.4.7: What should I do to prepare client code in my own
     applications to use performance-enhancing replication?

   * 16.3.4.8: When and how much can MySQL replication improve the
     performance of my system?

   * 16.3.4.9: How can I use replication to provide redundancy or high
     availability?

   * 16.3.4.10: How do I tell whether a master server is using
     statement-based or row-based binary logging format?

   * 16.3.4.11: How do I tell a slave to use row-based replication?

   * 16.3.4.12: How do I prevent *Note `GRANT': grant. and *Note
     `REVOKE': revoke. statements from replicating to slave machines?

   * 16.3.4.13: Does replication work on mixed operating systems (for
     example, the master runs on Linux while slaves run on Mac OS X and
     Windows)?

   * 16.3.4.14: Does replication work on mixed hardware architectures
     (for example, the master runs on a 64-bit machine while slaves run
     on 32-bit machines)?

*Questions and Answers* *16.3.4.1: ** Does the slave need to be
connected to the master all the time?  *

No, it does not. The slave can go down or stay disconnected for hours
or even days, and then reconnect and catch up on updates. For example,
you can set up a master/slave relationship over a dial-up link where
the link is up only sporadically and for short periods of time. The
implication of this is that, at any given time, the slave is not
guaranteed to be in sync with the master unless you take some special
measures.

To ensure that this is the case, you must not remove binary logs from
the master, where the information has not been replicated to the
slaves. Asynchronous replication can only work if the slave is able to
read the binary log from the last point in the binary logs where it had
read the replication statements.

*16.3.4.2: ** Do I have to enable networking on my master to enable
replication?  *

Networking must be enabled on the master. If networking is not enabled,
then the slave is unable to connect to the master and transfer the
binary log. Check that the `skip-networking' option has not been
enabled in your configuration file.

*16.3.4.3: ** How do I know how late a slave is compared to the master?
In other words, how do I know the date of the last statement replicated
by the slave?  *

You can read the `Seconds_Behind_Master' column in *Note `SHOW SLAVE
STATUS': show-slave-status.  See *Note
replication-implementation-details::.

When the slave SQL thread executes an event read from the master, it
modifies its own time to the event timestamp.  (This is why *Note
`TIMESTAMP': datetime. is well replicated.) In the `Time' column in the
output of *Note `SHOW PROCESSLIST': show-processlist, the number of
seconds displayed for the slave SQL thread is the number of seconds
between the timestamp of the last replicated event and the real time of
the slave machine. You can use this to determine the date of the last
replicated event. Note that if your slave has been disconnected from
the master for one hour, and then reconnects, you may immediately see
`Time' values like 3600 for the slave SQL thread in *Note `SHOW
PROCESSLIST': show-processlist. This is because the slave is executing
statements that are one hour old.

*16.3.4.4: ** How do I force the master to block updates until the slave
catches up?  *

Use the following procedure:

  1. On the master, execute these statements:

          mysql> FLUSH TABLES WITH READ LOCK;
          mysql> SHOW MASTER STATUS;

     Record the replication coordinates (the log file name and offset)
     from the output of the *Note `SHOW': show. statement.

  2. On the slave, issue the following statement, where the arguments
     to the `MASTER_POS_WAIT()' function are the replication coordinate
     values obtained in the previous step:

          mysql> SELECT MASTER_POS_WAIT('LOG_NAME', LOG_OFFSET);

     The *Note `SELECT': select. statement blocks until the slave
     reaches the specified log file and offset. At that point, the
     slave is in synchrony with the master and the statement returns.

  3. On the master, issue the following statement to allow the master
     to begin processing updates again:

          mysql> UNLOCK TABLES;

*16.3.4.5: ** What issues should I be aware of when setting up two-way
replication?  *

MySQL replication currently does not support any locking protocol
between master and slave to guarantee the atomicity of a distributed
(cross-server) update. In other words, it is possible for client A to
make an update to co-master 1, and in the meantime, before it
propagates to co-master 2, client B could make an update to co-master 2
that makes the update of client A work differently than it did on
co-master 1. Thus, when the update of client A makes it to co-master 2,
it produces tables that are different from what you have on co-master
1, even after all the updates from co-master 2 have also propagated.
This means that you should not chain two servers together in a two-way
replication relationship unless you are sure that your updates can
safely happen in any order, or unless you take care of mis-ordered
updates somehow in the client code.

You should also realize that two-way replication actually does not
improve performance very much (if at all) as far as updates are
concerned. Each server must do the same number of updates, just as you
would have a single server do. The only difference is that there is a
little less lock contention, because the updates originating on another
server are serialized in one slave thread. Even this benefit might be
offset by network delays.

*16.3.4.6: ** ** ** How can I use replication to improve performance of
my system?  *

You should set up one server as the master and direct all writes to it.
Then configure as many slaves as you have the budget and rackspace for,
and distribute the reads among the master and the slaves. You can also
start the slaves with the `--skip-innodb', `--low-priority-updates', and
`--delay-key-write=ALL' options to get speed improvements on the slave
end. In this case, the slave uses non-transactional `MyISAM' tables
instead of `InnoDB' tables to get more speed by eliminating
transactional overhead.

*16.3.4.7: ** What should I do to prepare client code in my own
applications to use performance-enhancing replication?  *

See the guide to using replication as a scale-out solution, *Note
replication-solutions-scaleout::.

*16.3.4.8: ** When and how much can MySQL replication improve the
performance of my system?  *

MySQL replication is most beneficial for a system that processes
frequent reads and infrequent writes. In theory, by using a
single-master/multiple-slave setup, you can scale the system by adding
more slaves until you either run out of network bandwidth, or your
update load grows to the point that the master cannot handle it.

To determine how many slaves you can use before the added benefits
begin to level out, and how much you can improve performance of your
site, you need to know your query patterns, and to determine
empirically by benchmarking the relationship between the throughput for
reads (reads per second, or `reads') and for writes (`writes') on a
typical master and a typical slave. The example here shows a rather
simplified calculation of what you can get with replication for a
hypothetical system.

Let's say that system load consists of 10% writes and 90% reads, and we
have determined by benchmarking that `reads' is 1200 - 2 x `writes'. In
other words, the system can do 1,200 reads per second with no writes,
the average write is twice as slow as the average read, and the
relationship is linear. Let us suppose that the master and each slave
have the same capacity, and that we have one master and N slaves. Then
we have for each server (master or slave):

`reads = 1200 - 2 x writes'

`reads = 9 x writes / (N + 1)' (reads are split, but writes go to all
servers)

`9 x writes / (N + 1) + 2 x writes = 1200'

`writes = 1200 / (2 + 9/(N+1))'

The last equation indicates the maximum number of writes for N slaves,
given a maximum possible read rate of 1,200 per minute and a ratio of
nine reads per write.

This analysis yields the following conclusions:

   * If N = 0 (which means we have no replication), our system can
     handle about 1200/11 = 109 writes per second.

   * If N = 1, we get up to 184 writes per second.

   * If N = 8, we get up to 400 writes per second.

   * If N = 17, we get up to 480 writes per second.

   * Eventually, as N approaches infinity (and our budget negative
     infinity), we can get very close to 600 writes per second,
     increasing system throughput about 5.5 times. However, with only
     eight servers, we increase it nearly four times.

Note that these computations assume infinite network bandwidth and
neglect several other factors that could be significant on your system.
In many cases, you may not be able to perform a computation similar to
the one just shown that accurately predicts what will happen on your
system if you add N replication slaves.  However, answering the
following questions should help you decide whether and by how much
replication will improve the performance of your system:

   * What is the read/write ratio on your system?

   * How much more write load can one server handle if you reduce the
     reads?

   * For how many slaves do you have bandwidth available on your
     network?

*16.3.4.9: ** How can I use replication to provide redundancy or high
availability?  *

How you implement redundancy is entirely dependent on your application
and circumstances. High-availability solutions (with automatic
failover) require active monitoring and either custom scripts or third
party tools to provide the failover support from the original MySQL
server to the slave.

To handle the process manually, you should be able to switch from a
failed master to a pre-configured slave by altering your application to
talk to the new server or by adjusting the DNS for the MySQL server
from the failed server to the new server.

For more information and some example solutions, see *Note
replication-solutions-switch::.

*16.3.4.10: ** How do I tell whether a master server is using
statement-based or row-based binary logging format?  *

Check the value of the `binlog_format' system variable:

     mysql> SHOW VARIABLES LIKE 'binlog_format';

The value shown is one of `STATEMENT', `ROW', or `MIXED'. When `MIXED'
mode is in use, row-based replication is preferred but replication
switches automatically to statement-based format under certain
conditions; see *Note binary-log-mixed::, for information about when
this may occur.

*16.3.4.11: ** How do I tell a slave to use row-based replication?  *

Slaves automatically know which format to use.

*16.3.4.12: ** How do I prevent *Note `GRANT': grant. and *Note
`REVOKE': revoke. statements from replicating to slave machines?  *

Start the server with the `--replicate-wild-ignore-table=mysql.%'
option.

*16.3.4.13: ** Does replication work on mixed operating systems (for
example, the master runs on Linux while slaves run on Mac OS X and
Windows)?  *

Yes.

*16.3.4.14: ** Does replication work on mixed hardware architectures
(for example, the master runs on a 64-bit machine while slaves run on
32-bit machines)?  *

Yes.


File: manual.info,  Node: replication-problems,  Next: replication-bugs,  Prev: replication-faq,  Up: replication-notes

16.3.5 Troubleshooting Replication
----------------------------------

If you have followed the instructions, and your replication setup is
not working, the first thing to do is _check the error log for
messages_. Many users have lost time by not doing this soon enough
after encountering problems.

If you cannot tell from the error log what the problem was, try the
following techniques:

   * Verify that the master has binary logging enabled by issuing a
     *Note `SHOW MASTER STATUS': show-master-status. statement.  If
     logging is enabled, `Position' is non-zero. If binary logging is
     not enabled, verify that you are running the master with the
     `--log-bin' and `--server-id' options.

   * Verify that the slave is running. Use *Note `SHOW SLAVE STATUS':
     show-slave-status. to check whether the `Slave_IO_Running' and
     `Slave_SQL_Running' values are both `Yes'. If not, verify the
     options that were used when starting the slave server. For example,
     `--skip-slave-start' prevents the slave threads from starting
     until you issue a *Note `START SLAVE': start-slave. statement.

   * If the slave is running, check whether it established a connection
     to the master. Use *Note `SHOW PROCESSLIST': show-processlist,
     find the I/O and SQL threads and check their `State' column to see
     what they display. See *Note replication-implementation-details::.
     If the I/O thread state says `Connecting to master', check the
     following:

        * Verify the privileges for the user being used for replication
          on the master.

        * Check that the host name of the master is correct and that
          you are using the correct port to connect to the master.  The
          port used for replication is the same as used for client
          network communication (the default is `3306'). For the host
          name, ensure that the name resolves to the correct IP address.

        * Check that networking on the master has not been disabled.
          Look for the `skip-networking' option in the configuration
          file. It should either be commented out or deleted entirely.

        * If the master has a firewall or IP filtering configuration,
          ensure that the network port being used for MySQL is not
          being filtered.

        * Check that you can reach the master by using `ping' or
          `traceroute'/`tracert' to reach the host.

   * If the slave was running previously but has stopped, the reason
     usually is that some statement that succeeded on the master failed
     on the slave. This should never happen if you have taken a proper
     snapshot of the master, and never modified the data on the slave
     outside of the slave thread. If the slave stops unexpectedly, it
     is a bug or you have encountered one of the known replication
     limitations described in *Note replication-features::. If it is a
     bug, see *Note replication-bugs::, for instructions on how to
     report it.

   * If a statement that succeeded on the master refuses to run on the
     slave, try the following procedure if it is not feasible to do a
     full database resynchronization by deleting the slave's databases
     and copying a new snapshot from the master:

       1. Determine whether the affected table on the slave is
          different from the master table. Try to understand how this
          happened. Then make the slave's table identical to the
          master's and run *Note `START SLAVE': start-slave.

       2. If the preceding step does not work or does not apply, try to
          understand whether it would be safe to make the update
          manually (if needed) and then ignore the next statement from
          the master.

       3. If you decide that you can skip the next statement from the
          master, issue the following statements:

               mysql> SET GLOBAL SQL_SLAVE_SKIP_COUNTER = N;
               mysql> START SLAVE;

          The value of N should be 1 if the next statement from the
          master does not use `AUTO_INCREMENT' or `LAST_INSERT_ID()'.
          Otherwise, the value should be 2. The reason for using a
          value of 2 for statements that use `AUTO_INCREMENT' or
          `LAST_INSERT_ID()' is that they take two events in the binary
          log of the master.

          See also *Note set-global-sql-slave-skip-counter::.

       4. If you are sure that the slave started out perfectly
          synchronized with the master, and that no one has updated the
          tables involved outside of the slave thread, then presumably
          the discrepancy is the result of a bug. If you are running
          the most recent version of MySQL, please report the problem.
          If you are running an older version, try upgrading to the
          latest production release to determine whether the problem
          persists.


File: manual.info,  Node: replication-bugs,  Prev: replication-problems,  Up: replication-notes

16.3.6 How to Report Replication Bugs or Problems
-------------------------------------------------

When you have determined that there is no user error involved, and
replication still either does not work at all or is unstable, it is
time to send us a bug report. We need to obtain as much information as
possible from you to be able to track down the bug.  Please spend some
time and effort in preparing a good bug report.

If you have a repeatable test case that demonstrates the bug, please
enter it into our bugs database using the instructions given in *Note
bug-reports::. If you have a `phantom' problem (one that you cannot
duplicate at will), use the following procedure:

  1. Verify that no user error is involved. For example, if you update
     the slave outside of the slave thread, the data goes out of
     synchrony, and you can have unique key violations on updates. In
     this case, the slave thread stops and waits for you to clean up
     the tables manually to bring them into synchrony. _This is not a
     replication problem. It is a problem of outside interference
     causing replication to fail._

  2. Run the slave with the `--log-slave-updates' and `--log-bin'
     options. These options cause the slave to log the updates that it
     receives from the master into its own binary logs.

  3. Save all evidence before resetting the replication state. If we
     have no information or only sketchy information, it becomes
     difficult or impossible for us to track down the problem. The
     evidence you should collect is:

        * All binary logs from the master

        * All binary logs from the slave

        * The output of *Note `SHOW MASTER STATUS': show-master-status.
          from the master at the time you discovered the problem

        * The output of *Note `SHOW SLAVE STATUS': show-slave-status.
          from the slave at the time you discovered the problem

        * Error logs from the master and the slave

  4. Use *Note `mysqlbinlog': mysqlbinlog. to examine the binary logs.
     The following should be helpful to find the problem statement.
     LOG_POS and LOG_FILE are the `Master_Log_File' and
     `Read_Master_Log_Pos' values from *Note `SHOW SLAVE STATUS':
     show-slave-status.

          shell> mysqlbinlog --start-position=LOG_POS LOG_FILE | head

After you have collected the evidence for the problem, try to isolate
it as a separate test case first. Then enter the problem with as much
information as possible into our bugs database using the instructions
at *Note bug-reports::.


File: manual.info,  Node: replication-implementation,  Prev: replication-notes,  Up: replication

16.4 Replication Implementation
===============================

* Menu:

* replication-implementation-details::  Replication Implementation Details
* slave-logs::                   Replication Relay and Status Files
* replication-rules::            How Servers Evaluate Replication Rules

The basic mechanics of replication is based on the master server
keeping track of all changes to your databases (updates, deletes, and
so on) in its binary logs. The binary log serves as a written record of
each to the database from the moment the database was started. The
binary log contains records of all the statements which edit or modify
either the database structure or the data that the structure contains.
Typically *Note `SELECT': select.  statements are not recorded, as they
do not modify the database data or structure.

Each slave that connects to the master receives a copy of the binary
log, and executes the events within the binary log. This has the effect
of repeating the original statements and changes just as they were made
on the master. Tables are created or their structure modified, and data
is inserted, deleted and updated according to the statements that were
originally executed on the master.

Because each slave is independent, the replaying of the statements in
the masters binary log can occur on each slave that is connected to the
master. In addition, because each slave only receives a copy of the
binary log by requesting it from the master (it pulls the data from the
master, rather than the master pushing the data to the slave), the
slave is able to read and update the copy of the database at its own
pace and rate and can start and stop the replication process at will
without affecting the master or the slaves ability to update to the
latest database status.

For more information on the specifics of the replication
implementation, see *Note replication-implementation-details::.

Slaves and masters report their status in respect of the replication
process regularly so that you can monitor the situation. For
information on slave states, see *Note slave-io-thread-states::, and
*Note slave-sql-thread-states::. For master states, see *Note
master-thread-states::.

The master binary log is written to a local relay log on the slave
before it is processed. The slave also records information about the
current position with the master's binary log and the local relayed
log. See *Note slave-logs::.

Databases and tables are updated on the slave according to a set of
rules that are applied according to the various configuration options
and variables that control statement evaluation. For details on how
these rules are applied, see *Note replication-rules::.


File: manual.info,  Node: replication-implementation-details,  Next: slave-logs,  Prev: replication-implementation,  Up: replication-implementation

16.4.1 Replication Implementation Details
-----------------------------------------

MySQL replication capabilities are implemented using three threads (one
on the master server and two on the slave):

   * Slave I/O thread

     When a *Note `START SLAVE': start-slave. statement is issued on a
     slave server, the slave creates an _I/O thread_, which connects to
     the master and asks it to send the updates recorded in its binary
     logs.

     The slave I/O thread reads the updates that the master' `Binlog
     Dump' thread sends (see next item) and copies them to local files
     -- known as _relay logs_ ‐ in the slave's data directory.

     The state of this thread is shown as `Slave_IO_running' in the
     output of *Note `SHOW SLAVE STATUS': show-slave-status. or as
     `Slave_running' in the output of *Note `SHOW STATUS': show-status.

   * Binlog dump thread

     The master creates a thread to send the binary log contents to the
     slave. This thread can be identified in the output of *Note `SHOW
     PROCESSLIST': show-processlist. on the master as the `Binlog Dump'
     thread.

     The binlog dump thread acquires a lock on the master's binary log
     for reading each event that is to be sent to the slave. As soon as
     the event has been read, the lock is released, even before the
     event is sent to the slave.

   * Slave SQL thread

     The slave creates this thread to read the relay logs that were
     written by the slave I/O thread. The _slave SQL thread_ is also
     used to execute the updates contained in the relay logs.

MySQL Enterprise

For constant monitoring of the status of slaves subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

In the preceding description, there are three threads per master/slave
connection. A master that has multiple slaves creates one binlog dump
thread for each currently-connected slave, and each slave has its own
I/O and SQL threads.

The slave uses two threads so that reading updates from the master and
executing them can be separated into two independent tasks.  Thus, the
task of reading statements is not slowed down if statement execution is
slow. For example, if the slave server has not been running for a
while, its I/O thread can quickly fetch all the binary log contents
from the master when the slave starts, even if the SQL thread lags far
behind. If the slave stops before the SQL thread has executed all the
fetched statements, the I/O thread has at least fetched everything so
that a safe copy of the statements is stored locally in the slave's
relay logs, ready for execution the next time that the slave starts.
This enables the master server to purge its binary logs sooner because
it no longer needs to wait for the slave to fetch their contents.

The *Note `SHOW PROCESSLIST': show-processlist. statement provides
information that tells you what is happening on the master and on the
slave regarding replication. See *Note thread-information::, for
descriptions of all replicated-related states.

The following example illustrates how the three threads show up in the
output from *Note `SHOW PROCESSLIST': show-processlist.

On the master server, the output from *Note `SHOW PROCESSLIST':
show-processlist. looks like this:

     mysql> SHOW PROCESSLIST\G
     *************************** 1. row ***************************
          Id: 2
        User: root
        Host: localhost:32931
          db: NULL
     Command: Binlog Dump
        Time: 94
       State: Has sent all binlog to slave; waiting for binlog to
              be updated
        Info: NULL

Here, thread 2 is a `Binlog Dump' replication thread for a connected
slave. The `State' information indicates that all outstanding updates
have been sent to the slave and that the master is waiting for more
updates to occur. If you see no `Binlog Dump' threads on a master
server, this means that replication is not running -- that is, that no
slaves are currently connected.

On the slave server, the output from *Note `SHOW PROCESSLIST':
show-processlist. looks like this:

     mysql> SHOW PROCESSLIST\G
     *************************** 1. row ***************************
          Id: 10
        User: system user
        Host:
          db: NULL
     Command: Connect
        Time: 11
       State: Waiting for master to send event
        Info: NULL
     *************************** 2. row ***************************
          Id: 11
        User: system user
        Host:
          db: NULL
     Command: Connect
        Time: 11
       State: Has read all relay log; waiting for the slave I/O
              thread to update it
        Info: NULL

This information indicates that thread 10 is the I/O thread that is
communicating with the master server, and thread 11 is the SQL thread
that is processing the updates stored in the relay logs. At the time
that the *Note `SHOW PROCESSLIST': show-processlist.  was run, both
threads were idle, waiting for further updates.

The value in the `Time' column can show how late the slave is compared
to the master. See *Note replication-faq::. The amount of time that the
slave lags behind the master that is required before the master
determines that the slave is no longer connected -- as with any other
client connection -- is dependent on the values of `net_write_timeout'
and `net_retry_count'; for more information about these, see *Note
server-system-variables::.


File: manual.info,  Node: slave-logs,  Next: replication-rules,  Prev: replication-implementation-details,  Up: replication-implementation

16.4.2 Replication Relay and Status Files
-----------------------------------------

* Menu:

* slave-logs-relaylog::          The Slave Relay Log
* slave-logs-status::            The Slave Status Files

During replication the MySQL server creates a number of files that are
used to hold the relayed binary log from the master, and record
information about the current status and location within the relayed
log. There are three file types used in the process:

   * The _relay log_ consists of the events read from the binary log of
     the master. Events in this binary log are executed on the slave as
     part of the replication thread.

   * The _master.info_ file contains the status and current
     configuration information for the slave's connectivity to the
     master. The file holds information on the master host name, login
     credentials, and the current position within the master's binary
     log.

   * The _relay-log.info_ file holds the status information about the
     execution point within the slave's relay log files.

The relationship between the three files and the replication process is
as follows. The `master.info' file retains the point within the master
binary log that has been read from the master. These read events are
written to the relay log.  The `relay-log.info' file records the
position within the relay log of the statements that have been executed.


File: manual.info,  Node: slave-logs-relaylog,  Next: slave-logs-status,  Prev: slave-logs,  Up: slave-logs

16.4.2.1 The Slave Relay Log
............................

By default, relay log file names have the form
`HOST_NAME-relay-bin.NNNNNN', where HOST_NAME is the name of the slave
server host and NNNNNN is a sequence number. Successive relay log files
are created using successive sequence numbers, beginning with `000001'.
The slave uses an index file to track the relay log files currently in
use. The default relay log index file name is
`HOST_NAME-relay-bin.index'.  By default, the slave server creates
relay log files in its data directory.

The default file names for relay logs and relay log index files can be
overridden with, respectively, the `--relay-log' and
`--relay-log-index' server options (see *Note replication-options::).
For this reason, changing a replication slave's host name can cause
replication to fail with the errors `Failed to open the relay log' and
`Could not find target log during relay log initialization'. This is a
known issue which we intend to fix in a future MySQL release (see
Bug#2122 (http://bugs.mysql.com/2122)). If you anticipate that a
slave's host name may change in the future (for example, if networking
is set up on the slave such that its host name can be modified via
DHCP), then you can use these options to prevent this problem from
occurring. However, if you encounter this issue, one way to work around
it is to stop the slave server, prepend the contents of the old relay
log index file to the new one, then restart the slave. On a Unix
system, this can be done as shown here, where NEW_HOST_NAME is the new
host name and OLD_HOST_NAME is the old one:

     shell> cat NEW_HOST_NAME-relay-bin.index >> OLD_HOST_NAME-relay-bin.index

     shell> mv OLD_HOST_NAME-relay-bin.index NEW_HOST_NAME-relay-bin.index

Relay logs have the same format as binary logs and can be read using
*Note `mysqlbinlog': mysqlbinlog. The SQL thread automatically deletes
each relay log file as soon as it has executed all events in the file
and no longer needs it. There is no explicit mechanism for deleting
relay logs because the SQL thread takes care of doing so. However,
*Note `FLUSH LOGS': flush.  rotates relay logs, which influences when
the SQL thread deletes them.

A slave server creates a new relay log file under the following
conditions:

   * Each time the I/O thread starts.

   * When the logs are flushed; for example, with *Note `FLUSH LOGS':
     flush.  or *Note `mysqladmin flush-logs': mysqladmin.

   * When the size of the current relay log file becomes too large. The
     meaning of `too large' is determined as follows:

        * If the value of `max_relay_log_size' is greater than 0, that
          is the maximum relay log file size.

        * If the value of `max_relay_log_size' is 0, `max_binlog_size'
          determines the maximum relay log file size.


File: manual.info,  Node: slave-logs-status,  Prev: slave-logs-relaylog,  Up: slave-logs

16.4.2.2 The Slave Status Files
...............................

A slave replication server creates two small files in the data
directory. These _status files_ are named `master.info' and
`relay-log.info' by default. Their names can be changed by using the
`--master-info-file' and `--relay-log-info-file' options.  See *Note
replication-options::.

The two status files contain information like that shown in the output
of the *Note `SHOW SLAVE STATUS': show-slave-status.  statement, which
is discussed in *Note replication-slave-sql::. Because the status files
are stored on disk, they survive a slave server's shutdown. The next
time the slave starts up, it reads the two files to determine how far
it has proceeded in reading binary logs from the master and in
processing its own relay logs.

The I/O thread updates the `master.info' file. The following table
shows the correspondence between the lines in the file and the columns
displayed by *Note `SHOW SLAVE STATUS': show-slave-status.

*Line*      *Status Column*           *Description*
1                                     Number of lines in the file
2           `Master_Log_File'         The name of the master binary log
                                      currently being read from the
                                      master.
3           `Read_Master_Log_Pos'     The current position within the
                                      master binary log that have been
                                      read from the master.
4           `Master_Host'             The host name of the master.
5           `Master_User'             The user name used to connect to
                                      the master.
6           Password (not shown by    The password used to connect to the
            *Note `SHOW SLAVE         master.
            STATUS':                  
            show-slave-status.)       
7           `Master_Port'             The network port used to connect to
                                      the master.
8           `Connect_Retry'           The period (in seconds) that the
                                      slave will wait before trying to
                                      reconnect to the master.
9           `Master_SSL_Allowed'      Indicates whether the server
                                      supports SSL connections.
10          `Master_SSL_CA_File'      The file used for the Certificate
                                      Authority (CA) certificate.
11          `Master_SSL_CA_Path'      The path to the Certificate
                                      Authority (CA) certificates.
12          `Master_SSL_Cert'         The name of the SSL certificate
                                      file.
13          `Master_SSL_Cipher'       The name of the cipher in use for
                                      the SSL connection.
14          `Master_SSL_Key'          The name of the SSL key file.
15          `Master_SSL_Verify_Server_Cert'Whether to verify the server
                                      certificate.
17          `Replicate_Ignore_Server_Ids'The number of server IDs to be
                                      ignored, followed by the actual
                                      server IDs. Added in MySQL 6.0.10.

The SQL thread updates the `relay-log.info' file. The following table
shows the correspondence between the lines in the file and the columns
displayed by *Note `SHOW SLAVE STATUS': show-slave-status.

*Line*      *Status Column*           *Description*
1           `Relay_Log_File'          The name of the current relay log
                                      file.
2           `Relay_Log_Pos'           The current position within the
                                      relay log file. Events up to this
                                      position have been executed on the
                                      slave database.
3           `Relay_Master_Log_File'   The name of the master binary log
                                      file from which the events in the
                                      relay log file were read.
4           `Exec_Master_Log_Pos'     The equivalent position within the
                                      master's binary log file of events
                                      that have already been executed.

The contents of the `relay-log.info' file and the states shown by the
`SHOW SLAVE STATES' command may not match if the `relay-log.info' file
has not been flushed to disk. Ideally, you should only view
`relay-log.info' on a slave that is offline (i.e. `mysqld' is not
running). For a running system, *Note `SHOW SLAVE STATUS':
show-slave-status. should be used.


File: manual.info,  Node: replication-rules,  Prev: slave-logs,  Up: replication-implementation

16.4.3 How Servers Evaluate Replication Rules
---------------------------------------------

If a master server does not write a statement to its binary log, the
statement is not replicated. If the server does log the statement, the
statement is sent to all slaves and each slave determines whether to
execute it or ignore it.

On the master you can control which databases write events to the
binary log using the `--binlog-do-db' and `--binlog-ignore-db' options
to control binary logging. For a description of the rules that servers
use in evaluating these options, see *Note binary-log::. You should not
use these options to control the databases and tables that are
replicated, instead, use filtering on the slave to control the events
that are executed on the slave.

On the slave side, decisions about whether to execute or ignore
statements received from the master are made according to the
`--replicate-*' options that the slave was started with. (See *Note
replication-options::.) The slave evaluates these options using the
following procedure, which first checks the database-level options and
then the table-level options.

In the simplest case, when there are no `--replicate-*' options, the
procedure yields the result that the slave executes all statements that
it receives from the master. Otherwise, the result depends on the
particular options given. In general, to make it easier to determine
what effect an option set will have, it is recommended that you avoid
mixing `do' and `ignore' options, or wildcard and non-wildcard options.

*Stage 1. Check the database options.*

At this stage, the slave checks whether there are any
`--replicate-do-db' or `--replicate-ignore-db' options that specify
database-specific conditions:

   * _No_: Permit the statement and proceed to the table-checking stage.

   * _Yes_: Test the options using the same rules as for the
     `--binlog-do-db' and `--binlog-ignore-db' options to determine
     whether to permit or ignore the statement. What is the result of
     the test?

        * _Permit_: Do not execute the statement immediately. Defer the
          decision and proceed to the table-checking stage.

        * _Ignore_: Ignore the statement and exit.

This stage can permit a statement for further option-checking, or cause
it to be ignored. However, statements that are permitted at this stage
are not actually executed yet. Instead, they pass to the following
stage that checks the table options.

*Stage 2. Check the table options.*

First, as a preliminary condition, the slave checks whether
statement-based replication is enabled. If so and the statement occurs
within a stored function, execute the statement and exit.  (If
row-based replication is enabled, the slave does not know whether a
statement occurred within a stored function on the master, so this
condition does not apply.)

Next, the slave checks for table options and evaluates them. If the
server reaches this point, it executes all statements if there are no
table options. If there are `do' table options, the statement must
match one of them if it is to be executed; otherwise, it is ignored. If
there are any `ignore' options, all statements are executed except
those that match any `ignore' option. The following steps describe how
this evaluation occurs in more detail.

  1. Are there any `--replicate-*-table' options?

        * _No_: There are no table restrictions, so all statements
          match. Execute the statement and exit.

        * _Yes_: There are table restrictions.  Evaluate the tables to
          be updated against them. There might be multiple tables to
          update, so loop through the following steps for each table
          looking for a matching option. In this case, the behavior
          depends on whether statement-based replication or row-based
          replication is enabled:

             * _Statement-based replication_: Proceed to the next step
               and begin evaluating the table options in the order
               shown (first the non-wild options, and then the wild
               options). Only tables that are to be updated are
               compared to the options. For example, if the statement
               is `INSERT INTO sales SELECT * FROM prices', only
               `sales' is compared to the options).  If several tables
               are to be updated (multiple-table statement), the first
               table that matches `do' or `ignore' wins. That is, the
               server checks the first table against the options. If no
               decision could be made, it checks the second table
               against the options, and so on.

             * _Row-based replication_: All table row changes are
               filtered individually. For multiple-table updates, each
               table is filtered separately according to the options.
               Some updates may be executed and some not, depending on
               the options and the changes to be made. Row-based
               replication correctly handles cases that would not
               replicate correctly with statement-based replication, as
               in this example which assumes that tables in the `foo'
               database should be replicated:

                    mysql> USE bar;
                    mysql> INSERT INTO foo.sometable VALUES (1);

  2. Are there any `--replicate-do-table' options?

        * _No_: Proceed to the next step.

        * _Yes_: Does the table match any of them?

             * _No_: Proceed to the next step.

             * _Yes_: Execute the statement and exit.

  3. Are there any `--replicate-ignore-table' options?

        * _No_: Proceed to the next step.

        * _Yes_: Does the table match any of them?

             * _No_: Proceed to the next step.

             * _Yes_: Ignore the statement and exit.

  4. Are there any `--replicate-wild-do-table' options?

        * _No_: Proceed to the next step.

        * _Yes_: Does the table match any of them?

             * _No_: Proceed to the next step.

             * _Yes_: Execute the statement and exit.

  5. Are there any `--replicate-wild-ignore-table' options?

        * _No_: Proceed to the next step.

        * _Yes_: Does the table match any of them?

             * _No_: Proceed to the next step.

             * _Yes_: Ignore the statement and exit.

  6. No `--replicate-*-table' option was matched. Is there another
     table to test against these options?

        * _No_: We have now tested all tables to be updated and could
          not match any option. Are there `--replicate-do-table' or
          `--replicate-wild-do-table' options?

             * _No_: There were no `do' table options, so no explicit
               `do' match is required. Execute the statement and exit.

             * _Yes_: There were `do' table options, so the statement
               is executed only with an explicit match to one of them.
               Ignore the statement and exit.

        * _Yes_: Loop.

Examples:

   * No `--replicate-*' options at all

     The slave executes all statements that it receives from the master.

   * `--replicate-*-db' options, but no table options

     The slave permits or ignores statements using the database
     options. Then it executes all statements permitted by those
     options because there are no table restrictions.

   * `--replicate-*-table' options, but no database options

     All statements are permitted at the database-checking stage
     because there are no database conditions. The slave executes or
     ignores statements based on the table options.

   * A mix of database and table options

     The slave permits or ignores statements using the database
     options. Then it evaluates all statements permitted by those
     options according to the table options. In some cases, this
     process can yield what might seem a counterintuitive result.
     Consider the following set of options:

          [mysqld]
          replicate-do-db    = db1
          replicate-do-table = db2.mytbl2

     Suppose that `db1' is the default database and the slave receives
     this statement:

          INSERT INTO mytbl1 VALUES(1,2,3);

     The database is `db1', which matches the `--replicate-do-db'
     option at the database-checking stage. The algorithm then proceeds
     to the table-checking stage. If there were no table options, the
     statement would be executed. However, because the options include
     a `do' table option, the statement must match if it is to be
     executed. The statement does not match, so it is ignored. (The
     same would happen for any table in `db1'.)


File: manual.info,  Node: partitioning,  Next: stored-programs-views,  Prev: replication,  Up: Top

17 Partitioning
***************

* Menu:

* partitioning-overview::        Overview of Partitioning in MySQL
* partitioning-types::           Partition Types
* partitioning-management::      Partition Management
* partitioning-pruning::         Partition Pruning
* partitioning-limitations::     Restrictions and Limitations on Partitioning

This chapter discusses MySQL's implementation of _user-defined
partitioning_. You can determine whether your MySQL Server supports
partitioning by means of a *Note `SHOW VARIABLES': show-variables.
command such as this one:

     mysql> SHOW VARIABLES LIKE '%partition%';

     +-------------------+-------+
     | Variable_name     | Value |
     +-------------------+-------+
     | have_partitioning | YES   |
     +-------------------+-------+
     1 row in set (0.00 sec)

You can also check the output of the *Note `SHOW PLUGINS':
show-plugins. statement, as shown here:


     mysql> SHOW PLUGINS;
     +------------+----------+----------------+---------+---------+
     | Name       | Status   | Type           | Library | License |
     +------------+----------+----------------+---------+---------+
     | binlog     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
     *| partition  | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |*
     | ARCHIVE    | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
     | BLACKHOLE  | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
     | CSV        | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
     | FEDERATED  | DISABLED | STORAGE ENGINE | NULL    | GPL     |
     | MEMORY     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
     | InnoDB     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
     | MRG_MYISAM | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
     | MyISAM     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
     | ndbcluster | DISABLED | STORAGE ENGINE | NULL    | GPL     |
     +------------+----------+----------------+---------+---------+
     11 rows in set (0.00 sec)

If you do not see the `have_partitioning' variable with the value `YES'
listed in the output of an appropriate *Note `SHOW VARIABLES':
show-variables. statement, or if you do not see the `partition' plugin
listed with the value `ACTIVE' for the `Status' column in the output of
*Note `SHOW PLUGINS': show-plugins.  (show in bold text in the example
just given), then your version of MySQL does not support partitioning.

Community binaries provided by Sun Microsystems include partitioning
support. For information about partitioning support offered in
commercial MySQL Server binaries, see `MySQL Enterprise Server 5.1'
(http://www.mysql.com/products/enterprise/server.html), on the MySQL
website.

If you are compiling MySQL 6.0 from source, the build must be
configured using `--with-partition' to enable partitioning.

If your MySQL binary is built with partitioning support, nothing
further needs to be done in order to enable it (for example, no special
entries are required in your `my.cnf' file).

An introduction to partitioning and partitioning concepts may be found
in *Note partitioning-overview::.

MySQL supports several types of partitioning, which are discussed in
*Note partitioning-types::, as well as subpartitioning, which is
described in *Note partitioning-subpartitions::.

Methods of adding, removing, and altering partitions in existing
partitioned tables are covered in *Note partitioning-management::.

Table maintenance commands for use with partitioned tables are
discussed in *Note partitioning-maintenance::.

The *Note `PARTITIONS': partitions-table. table in the
`INFORMATION_SCHEMA' database provides information about partitions and
partitioned tables. See *Note partitions-table::, for more information;
for some examples of queries against this table, see *Note
partitioning-handling-nulls::.

The partitioning implementation in MySQL 6.0 is still undergoing
development. For known issues with MySQL partitioning, see *Note
partitioning-limitations::, where we have noted these.

You may also find the following resources to be useful when working
with partitioned tables.

Additional Resources

Other sources of information about user-defined partitioning in MySQL
include the following:

   * MySQL Partitioning Forum (http://forums.mysql.com/list.php?106)

     This is the official discussion forum for those interested in or
     experimenting with MySQL Partitioning technology. It features
     announcements and updates from MySQL developers and others. It is
     monitored by members of the Partitioning Development and
     Documentation Teams.

   * Mikael Ronstro"m's Blog (http://mikaelronstrom.blogspot.com/)

     MySQL Partitioning Architect and Lead Developer Mikael Ronstro"m
     frequently posts articles here concerning his work with MySQL
     Partitioning and MySQL Cluster.

   * PlanetMySQL (http://www.planetmysql.org/)

     A MySQL news site featuring MySQL-related blogs, which should be
     of interest to anyone using my MySQL. We encourage you to check
     here for links to blogs kept by those working with MySQL
     Partitioning, or to have your own blog added to those covered.

MySQL 6.0 binaries are available from
`http://dev.mysql.com/downloads/mysql/6.0.html'.  However, for the
latest partitioning bugfixes and feature additions, you can obtain the
source from our Bazaar repository. To enable partitioning, you need to
compile the server using the `--with-partition' option. For more
information about building MySQL, see *Note installing-source::. If you
have problems compiling a partitioning-enabled MySQL 6.0 build, check
the MySQL Partitioning Forum (http://forums.mysql.com/list.php?106) and
ask for assistance there if you do not find a solution to your problem
already posted.


File: manual.info,  Node: partitioning-overview,  Next: partitioning-types,  Prev: partitioning,  Up: partitioning

17.1 Overview of Partitioning in MySQL
======================================

This section provides a conceptual overview of partitioning in MySQL
6.0.

For information on partitioning restrictions and feature limitations,
see *Note partitioning-limitations::.

The SQL standard does not provide much in the way of guidance regarding
the physical aspects of data storage. The SQL language itself is
intended to work independently of any data structures or media
underlying the schemas, tables, rows, or columns with which it works.
Nonetheless, most advanced database management systems have evolved
some means of determining the physical location to be used for storing
specific pieces of data in terms of the file system, hardware or even
both. In MySQL, the `InnoDB' storage engine has long supported the
notion of a tablespace, and the MySQL Server, even prior to the
introduction of partitioning, could be configured to employ different
physical directories for storing different databases (see *Note
symbolic-links::, for an explanation of how this is done).

_Partitioning_ takes this notion a step further, by allowing you to
distribute portions of individual tables across a file system according
to rules which you can set largely as needed. In effect, different
portions of a table are stored as separate tables in different
locations. The user-selected rule by which the division of data is
accomplished is known as a _partitioning function_, which in MySQL can
be the modulus, simple matching against a set of ranges or value lists,
an internal hashing function, or a linear hashing function. The
function is selected according to the partitioning type specified by
the user, and takes as its parameter the value of a user-supplied
expression. This expression can be either an integer column value, or a
function acting on one or more column values and returning an integer.
The value of this expression is passed to the partitioning function,
which returns an integer value representing the number of the partition
in which that particular record should be stored. This function must be
non-constant and non-random. It may not contain any queries, but may
use an SQL expression that is valid in MySQL, as long as that
expression returns either `NULL' or an integer INTVAL such that

     -MAXVALUE <= INTVAL <= MAXVALUE

(`MAXVALUE' is used to represent the least upper bound for the type of
integer in question.  `-MAXVALUE' represents the greatest lower bound.)
There are some additional restrictions on partitioning functions; see
*Note partitioning-limitations::, for more information about these.

Examples of partitioning functions can be found in the discussions of
partitioning types later in this chapter (see *Note
partitioning-types::), as well as in the partitioning syntax
descriptions given in *Note create-table::.

This is known as _horizontal partitioning_ -- that is, different rows
of a table may be assigned to different physical partitions. MySQL 6.0
does not support _vertical partitioning_, in which different columns of
a table are assigned to different physical partitions. There are not at
this time any plans to introduce vertical partitioning into MySQL 6.0.

For creating partitioned tables, you can use most storage engines that
are supported by your MySQL server; the MySQL partitioning engine runs
in a separate layer and can interact with any of these. In MySQL 6.0,
all partitions of the same partitioned table must use the same storage
engine; for example, you cannot use `MyISAM' for one partition and
`InnoDB' for another. However, there is nothing preventing you from
using different storage engines for different partitioned tables on the
same MySQL server or even in the same database.

*Note*:

MySQL partitioning cannot be used with the `MERGE' or `CSV' storage
engines.

To employ a particular storage engine for a partitioned table, it is
necessary only to use the `[STORAGE] ENGINE' option just as you would
for a non-partitioned table. However, you should keep in mind that
`[STORAGE] ENGINE' (and other table options) need to be listed _before_
any partitioning options are used in a *Note `CREATE TABLE':
create-table. statement. This example shows how to create a table that
is partitioned by hash into 6 partitions and which uses the `InnoDB'
storage engine:

     CREATE TABLE ti (id INT, amount DECIMAL(7,2), tr_date DATE)
         ENGINE=INNODB
         PARTITION BY HASH( MONTH(tr_date) )
         PARTITIONS 6;

*Note*:

Each `PARTITION' clause can include a `[STORAGE] ENGINE' option, but in
MySQL 6.0 this has no effect.

*Important*:

Partitioning applies to all data and indexes of a table; you cannot
partition only the data and not the indexes, or _vice versa_, nor can
you partition only a portion of the table.

Data and indexes for each partition can be assigned to a specific
directory using the `DATA DIRECTORY' and `INDEX DIRECTORY' options for
the `PARTITION' clause of the *Note `CREATE TABLE': create-table.
statement used to create the partitioned table.

*Note*:

Prior to MySQL 5.1.18, these options were permitted even when the
`NO_DIR_IN_CREATE' server SQL mode was in effect. (Bug#24633
(http://bugs.mysql.com/24633))

The `DATA DIRECTORY' and `INDEX DIRECTORY' options have no effect when
defining partitions for tables using the `InnoDB' storage engine.

`DATA DIRECTORY' and `INDEX DIRECTORY' are not supported for individual
partitions or subpartitions on Windows. Beginning with MySQL 6.0.5,
these options are ignored on Windows, except that a warning is
generated. (Bug#30459 (http://bugs.mysql.com/30459))

In addition, `MAX_ROWS' and `MIN_ROWS' can be used to determine the
maximum and minimum numbers of rows, respectively, that can be stored in
each partition. See *Note partitioning-management::, for more
information on these options.

Some of the advantages of partitioning include:

   * Being able to store more data in one table than can be held on a
     single disk or file system partition.

   * Data that loses its usefulness can often be easily be removed from
     the table by dropping the partition containing only that data.
     Conversely, the process of adding new data can in some cases be
     greatly facilitated by adding a new partition specifically for
     that data.

   * Some queries can be greatly optimized in virtue of the fact that
     data satisfying a given `WHERE' clause can be stored only on one
     or more partitions, thereby excluding any remaining partitions
     from the search. Because partitions can be altered after a
     partitioned table has been created, you can reorganize your data
     to enhance frequent queries that may not have been so when the
     partitioning scheme was first set up. This capability is sometimes
     referred to as _partition pruning_. For more information, see
     *Note partitioning-pruning::.

Other benefits usually associated with partitioning include those in
the following list. These features are not currently implemented in
MySQL Partitioning, but are high on our list of priorities.

   * Queries involving aggregate functions such as `SUM()' and
     `COUNT()' can easily be parallelized. A simple example of such a
     query might be `SELECT salesperson_id, COUNT(orders) as order_total
     FROM sales GROUP BY salesperson_id;'. By `parallelized,' we mean
     that the query can be run simultaneously on each partition, and
     the final result obtained merely by summing the results obtained
     for all partitions.

   * Achieving greater query throughput in virtue of spreading data
     seeks over multiple disks.

Be sure to check this section and chapter frequently for updates as
Partitioning development continues.


File: manual.info,  Node: partitioning-types,  Next: partitioning-management,  Prev: partitioning-overview,  Up: partitioning

17.2 Partition Types
====================

* Menu:

* partitioning-range::           `RANGE' Partitioning
* partitioning-list::            `LIST' Partitioning
* partitioning-hash::            `HASH' Partitioning
* partitioning-key::             `KEY' Partitioning
* partitioning-subpartitions::   Subpartitioning
* partitioning-handling-nulls::  How MySQL Partitioning Handles `NULL'

This section discusses the types of partitioning which are available in
MySQL 6.0. These include:

   * *`RANGE' partitioning*: Assigns rows to partitions based on column
     values falling within a given range. See *Note
     partitioning-range::.

   * *`LIST' partitioning*: Similar to partitioning by range, except
     that the partition is selected based on columns matching one of a
     set of discrete values. See *Note partitioning-list::.

   * *`HASH' partitioning*: A partition is selected based on the value
     returned by a user-defined expression that operates on column
     values in rows to be inserted into the table. The function may
     consist of any expression valid in MySQL that yields a
     non-negative integer value. See *Note partitioning-hash::.

   * *`KEY' partitioning*: Similar to partitioning by hash, except that
     only one or more columns to be evaluated are supplied, and the
     MySQL server provides its own hashing function. These columns can
     contain other than integer values, since the hashing function
     supplied by MySQL guarantees an integer result regardless of the
     column data type. See *Note partitioning-key::.

A very common use of database partitioning is to segregate data by
date. Some database systems support explicit date partitioning, which
MySQL does not implement in 6.0. However, it is not difficult in MySQL
to create partitioning schemes based on *Note `DATE': datetime, *Note
`TIME': time, or *Note `DATETIME': datetime. columns, or based on
expressions making use of such columns.

When partitioning by `KEY' or `LINEAR KEY', you can use a *Note `DATE':
datetime, *Note `TIME': time, or *Note `DATETIME': datetime. column as
the partitioning column without performing any modification of the
column value.  For example, this table creation statement is perfectly
valid in MySQL:

     CREATE TABLE members (
         firstname VARCHAR(25) NOT NULL,
         lastname VARCHAR(25) NOT NULL,
         username VARCHAR(16) NOT NULL,
         email VARCHAR(35),
         joined DATE NOT NULL
     )
     PARTITION BY KEY(joined)
     PARTITIONS 6;

MySQL's other partitioning types, however, require a partitioning
expression that yields an integer value or `NULL'. If you wish to use
date-based partitioning by `RANGE', `LIST', `HASH', or `LINEAR HASH',
you can simply employ a function that operates on a *Note `DATE':
datetime, *Note `TIME': time, or *Note `DATETIME': datetime. column and
returns such a value, as shown here:

     CREATE TABLE members (
         firstname VARCHAR(25) NOT NULL,
         lastname VARCHAR(25) NOT NULL,
         username VARCHAR(16) NOT NULL,
         email VARCHAR(35),
         joined DATE NOT NULL
     )
     PARTITION BY RANGE( YEAR(joined) ) (
         PARTITION p0 VALUES LESS THAN (1960),
         PARTITION p1 VALUES LESS THAN (1970),
         PARTITION p2 VALUES LESS THAN (1980),
         PARTITION p3 VALUES LESS THAN (1990),
         PARTITION p4 VALUES LESS THAN MAXVALUE
     );

Additional examples of partitioning using dates may be found here:

   * *Note partitioning-range::

   * *Note partitioning-hash::

   * *Note partitioning-linear-hash::

For more complex examples of date-based partitioning, see:

   * *Note partitioning-pruning::

   * *Note partitioning-subpartitions::

MySQL partitioning is optimized for use with the `TO_DAYS()' and
`YEAR()' functions. However, you can use other date and time functions
that return an integer or `NULL', such as `WEEKDAY()', `DAYOFYEAR()', or
`MONTH()'. See *Note date-and-time-functions::, for more information
about such functions.

It is important to remember -- regardless of the type of partitioning
that you use -- that partitions are always numbered automatically and
in sequence when created, starting with `0'. When a new row is inserted
into a partitioned table, it is these partition numbers that are used in
identifying the correct partition. For example, if your table uses 4
partitions, these partitions are numbered `0', `1', `2', and `3'. For
the `RANGE' and `LIST' partitioning types, it is necessary to ensure
that there is a partition defined for each partition number. For `HASH'
partitioning, the user function employed must return an integer value
greater than `0'. For `KEY' partitioning, this issue is taken care of
automatically by the hashing function which the MySQL server employs
internally.

Names of partitions generally follow the rules governing other MySQL
identifiers, such as those for tables and databases.  However, you
should note that partition names are not case-sensitive. For example,
the following *Note `CREATE TABLE': create-table. statement fails as
shown:

     mysql> CREATE TABLE t2 (val INT)
         -> PARTITION BY LIST(val)(
         ->     PARTITION mypart VALUES IN (1,3,5),
         ->     PARTITION MyPart VALUES IN (2,4,6)
         -> );
     ERROR 1488 (HY000): Duplicate partition name mypart

Failure occurs because MySQL sees no difference between the partition
names `mypart' and `MyPart'.

When you specify the number of partitions for the table, this must be
expressed as a positive, non-zero integer literal with no leading
zeroes, and may not be an expression such as `0.8E+01' or `6-2', even
if it evaluates to an integer value. Decimal fractions are not allowed.

In the sections that follow, we do not necessarily provide all possible
forms for the syntax that can be used for creating each partition type;
this information may be found in *Note create-table::.


File: manual.info,  Node: partitioning-range,  Next: partitioning-list,  Prev: partitioning-types,  Up: partitioning-types

17.2.1 `RANGE' Partitioning
---------------------------

A table that is partitioned by range is partitioned in such a way that
each partition contains rows for which the partitioning expression
value lies within a given range. Ranges should be contiguous but not
overlapping, and are defined using the `VALUES LESS THAN' operator. For
the next few examples, suppose that you are creating a table such as the
following to hold personnel records for a chain of 20 video stores,
numbered 1 through 20:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT NOT NULL,
         store_id INT NOT NULL
     );

This table can be partitioned by range in a number of ways, depending
on your needs. One way would be to use the `store_id' column. For
instance, you might decide to partition the table 4 ways by adding a
`PARTITION BY RANGE' clause as shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT NOT NULL,
         store_id INT NOT NULL
     )
     PARTITION BY RANGE (store_id) (
         PARTITION p0 VALUES LESS THAN (6),
         PARTITION p1 VALUES LESS THAN (11),
         PARTITION p2 VALUES LESS THAN (16),
         PARTITION p3 VALUES LESS THAN (21)
     );

In this partitioning scheme, all rows corresponding to employees
working at stores 1 through 5 are stored in partition `p0', to those
employed at stores 6 through 10 are stored in partition `p1', and so
on. Note that each partition is defined in order, from lowest to
highest.  This is a requirement of the `PARTITION BY RANGE' syntax; you
can think of it as being analogous to a series of `if ... elseif ...'
statements in C or Java in this regard.

It is easy to determine that a new row containing the data `(72,
'Michael', 'Widenius', '1998-06-25', NULL, 13)' is inserted into
partition `p2', but what happens when your chain adds a 21^st store?
Under this scheme, there is no rule that covers a row whose `store_id'
is greater than 20, so an error results because the server does not
know where to place it. You can keep this from occurring by using a
`catchall' `VALUES LESS THAN' clause in the *Note `CREATE TABLE':
create-table. statement that provides for all values greater than
highest value explicitly named:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT NOT NULL,
         store_id INT NOT NULL
     )
     PARTITION BY RANGE (store_id) (
         PARTITION p0 VALUES LESS THAN (6),
         PARTITION p1 VALUES LESS THAN (11),
         PARTITION p2 VALUES LESS THAN (16),
         _PARTITION p3 VALUES LESS THAN MAXVALUE_
     );

*Note*:

Another way to avoid an error when no matching value is found is to use
the `IGNORE' keyword as part of the *Note `INSERT': insert. statement.
For an example, see *Note partitioning-list::. Also see *Note insert::,
for general information about `IGNORE'.

`MAXVALUE' represents an integer value that is always greater than the
largest possible integer value (in mathematical language, it serves as
a _least upper bound_). Now, any rows whose `store_id' column value is
greater than or equal to 16 (the highest value defined) are stored in
partition `p3'. At some point in the future -- when the number of
stores has increased to 25, 30, or more -- you can use an *Note `ALTER
TABLE': alter-table.  statement to add new partitions for stores 21-25,
26-30, and so on (see *Note partitioning-management::, for details of
how to do this).

In much the same fashion, you could partition the table based on
employee job codes -- that is, based on ranges of `job_code' column
values. For example -- assuming that two-digit job codes are used for
regular (in-store) workers, three-digit codes are used for office and
support personnel, and four-digit codes are used for management
positions -- you could create the partitioned table using the following:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT NOT NULL,
         store_id INT NOT NULL
     )
     PARTITION BY RANGE (job_code) (
         PARTITION p0 VALUES LESS THAN (100),
         PARTITION p1 VALUES LESS THAN (1000),
         PARTITION p2 VALUES LESS THAN (10000)
     );

In this instance, all rows relating to in-store workers would be stored
in partition `p0', those relating to office and support staff in `p1',
and those relating to managers in partition `p2'.

It is also possible to use an expression in `VALUES LESS THAN' clauses.
However, MySQL must be able to evaluate the expression's return value
as part of a `LESS THAN' (`<') comparison.

Rather than splitting up the table data according to store number, you
can use an expression based on one of the two *Note `DATE': datetime.
columns instead. For example, let us suppose that you wish to partition
based on the year that each employee left the company; that is, the
value of `YEAR(separated)'. An example of a *Note `CREATE TABLE':
create-table. statement that implements such a partitioning scheme is
shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     )
     PARTITION BY RANGE ( YEAR(separated) ) (
         PARTITION p0 VALUES LESS THAN (1991),
         PARTITION p1 VALUES LESS THAN (1996),
         PARTITION p2 VALUES LESS THAN (2001),
         PARTITION p3 VALUES LESS THAN MAXVALUE
     );

In this scheme, for all employees who left before 1991, the rows are
stored in partition `p0'; for those who left in the years 1991 through
1995, in `p1'; for those who left in the years 1996 through 2000, in
`p2'; and for any workers who left after the year 2000, in `p3'.

Range partitioning is particularly useful when:

   * You want or need to delete `old' data. If you are using the
     partitioning scheme shown immediately above, you can simply use
     `ALTER TABLE employees DROP PARTITION p0;' to delete all rows
     relating to employees who stopped working for the firm prior to
     1991.  (See *Note alter-table::, and *Note
     partitioning-management::, for more information.) For a table with
     a great many rows, this can be much more efficient than running a
     *Note `DELETE': delete. query such as `DELETE FROM employees WHERE
     YEAR(separated) <= 1990;'.

   * You want to use a column containing date or time values, or
     containing values arising from some other series.

   * You frequently run queries that depend directly on the column used
     for partitioning the table. For example, when executing a query
     such as `EXPLAIN PARTITIONS SELECT COUNT(*) FROM employees WHERE
     separated BETWEEN '2000-01-01' AND '2000-12-31' GROUP BY
     store_id;', MySQL can quickly determine that only partition `p2'
     needs to be scanned because the remaining partitions cannot
     contain any records satisfying the `WHERE' clause. See *Note
     partitioning-pruning::, for more information about how this is
     accomplished.


File: manual.info,  Node: partitioning-list,  Next: partitioning-hash,  Prev: partitioning-range,  Up: partitioning-types

17.2.2 `LIST' Partitioning
--------------------------

List partitioning in MySQL is similar to range partitioning in many
ways. As in partitioning by `RANGE', each partition must be explicitly
defined. The chief difference is that, in list partitioning, each
partition is defined and selected based on the membership of a column
value in one of a set of value lists, rather than in one of a set of
contiguous ranges of values. This is done by using `PARTITION BY
LIST(EXPR)' where EXPR is a column value or an expression based on a
column value and returning an integer value, and then defining each
partition by means of a `VALUES IN (VALUE_LIST)', where VALUE_LIST is a
comma-separated list of integers.

*Note*:

In MySQL 6.0, it is possible to match against only a list of integers
(and possibly `NULL' -- see *Note partitioning-handling-nulls::) when
partitioning by `LIST'.

Unlike the case with partitions defined by range, list partitions do
not need to be declared in any particular order.  For more detailed
syntactical information, see *Note create-table::.

For the examples that follow, we assume that the basic definition of
the table to be partitioned is provided by the *Note `CREATE TABLE':
create-table. statement shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     );

(This is the same table used as a basis for the examples in *Note
partitioning-range::.)

Suppose that there are 20 video stores distributed among 4 franchises
as shown in the following table.

*Region*               *Store ID Numbers*
North                  3, 5, 6, 9, 17
East                   1, 2, 10, 11, 19, 20
West                   4, 12, 13, 14, 18
Central                7, 8, 15, 16

To partition this table in such a way that rows for stores belonging to
the same region are stored in the same partition, you could use the
*Note `CREATE TABLE': create-table.  statement shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     )
     PARTITION BY LIST(store_id) (
         PARTITION pNorth VALUES IN (3,5,6,9,17),
         PARTITION pEast VALUES IN (1,2,10,11,19,20),
         PARTITION pWest VALUES IN (4,12,13,14,18),
         PARTITION pCentral VALUES IN (7,8,15,16)
     );

This makes it easy to add or drop employee records relating to specific
regions to or from the table. For instance, suppose that all stores in
the West region are sold to another company.  All rows relating to
employees working at stores in that region can be deleted with the
query `ALTER TABLE employees DROP PARTITION pWest;', which can be
executed much more efficiently than the equivalent *Note `DELETE':
delete. statement `DELETE FROM employees WHERE store_id IN
(4,12,13,14,18);'.

As with `RANGE' partitioning, it is possible to combine `LIST'
partitioning with partitioning by hash or key to produce a composite
partitioning (subpartitioning). See *Note partitioning-subpartitions::.

Unlike the case with `RANGE' partitioning, there is no `catch-all' such
as `MAXVALUE'; all expected values for the partitioning expression
should be covered in `PARTITION ... VALUES IN (...)' clauses. An *Note
`INSERT': insert. statement containing an unmatched partitioning column
value fails with an error, as shown in this example:

     mysql> CREATE TABLE h2 (
         ->   c1 INT,
         ->   c2 INT
         -> )
         -> PARTITION BY LIST(c1) (
         ->   PARTITION p0 VALUES IN (1, 4, 7),
         ->   PARTITION p1 VALUES IN (2, 5, 8)
         -> );
     Query OK, 0 rows affected (0.11 sec)

     mysql> INSERT INTO h2 VALUES (3, 5);
     `ERROR 1525 (HY000): Table has no partition for value 3'

When inserting multiple rows using a single *Note `INSERT': insert.
statement, any rows coming before the row containing the unmatched
value are inserted, but any coming after it are not:

     mysql> SELECT * FROM h2;
     Empty set (0.00 sec)

     mysql> INSERT INTO h2 VALUES (4, 7), (3, 5), (6, 0);
     `ERROR 1525 (HY000): Table has no partition for value 3'
     mysql> SELECT * FROM h2;
     +------+------+
     | c1   | c2   |
     +------+------+
     |    4 |    7 |
     +------+------+
     1 row in set (0.00 sec)

You can cause this type of error to be ignored by using the `IGNORE'
key word. If you do so, rows containing unmatched partitioning column
values are not inserted, but any rows with matching values _are_
inserted, and no errors are reported:

     mysql> TRUNCATE h2;
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT * FROM h2;
     Empty set (0.00 sec)

     mysql> INSERT IGNORE INTO h2 VALUES (2, 5), (6, 10), (7, 5), (3, 1), (1, 9);
     Query OK, 3 rows affected (0.00 sec)
     Records: 5  Duplicates: 2  Warnings: 0

     mysql> SELECT * FROM h2;
     +------+------+
     | c1   | c2   |
     +------+------+
     |    7 |    5 |
     |    1 |    9 |
     |    2 |    5 |
     +------+------+
     3 rows in set (0.00 sec)


File: manual.info,  Node: partitioning-hash,  Next: partitioning-key,  Prev: partitioning-list,  Up: partitioning-types

17.2.3 `HASH' Partitioning
--------------------------

* Menu:

* partitioning-linear-hash::     `LINEAR HASH' Partitioning

Partitioning by `HASH' is used primarily to ensure an even distribution
of data among a predetermined number of partitions. With range or list
partitioning, you must specify explicitly into which partition a given
column value or set of column values is to be stored; with hash
partitioning, MySQL takes care of this for you, and you need only
specify a column value or expression based on a column value to be
hashed and the number of partitions into which the partitioned table is
to be divided.

To partition a table using `HASH' partitioning, it is necessary to
append to the *Note `CREATE TABLE': create-table. statement a
`PARTITION BY HASH (EXPR)' clause, where EXPR is an expression that
returns an integer. This can simply be the name of a column whose type
is one of MySQL's integer types. In addition, you will most likely want
to follow this with a `PARTITIONS NUM' clause, where NUM is a positive
integer representing the number of partitions into which the table is to
be divided.

For example, the following statement creates a table that uses hashing
on the `store_id' column and is divided into 4 partitions:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     )
     PARTITION BY HASH(store_id)
     PARTITIONS 4;

If you do not include a `PARTITIONS' clause, the number of partitions
defaults to `1'.

Using the `PARTITIONS' keyword without a number following it results in
a syntax error.

You can also use an SQL expression that returns an integer for EXPR.
For instance, you might want to partition based on the year in which an
employee was hired. This can be done as shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     )
     PARTITION BY HASH( YEAR(hired) )
     PARTITIONS 4;

EXPR must return a non-constant, non-random integer value (in other
words, it should be varying but deterministic), and must not contain
any prohibited constructs as described in *Note
partitioning-limitations::. You should also keep in mind that this
expression is evaluated each time a row is inserted or updated (or
possibly deleted); this means that very complex expressions may give
rise to performance issues, particularly when performing operations
(such as batch inserts) that affect a great many rows at one time.

The most efficient hashing function is one which operates upon a single
table column and whose value increases or decreases consistently with
the column value, as this allows for `pruning' on ranges of partitions.
That is, the more closely that the expression varies with the value of
the column on which it is based, the more efficiently MySQL can use the
expression for hash partitioning.

For example, where `date_col' is a column of type *Note `DATE':
datetime, then the expression `TO_DAYS(date_col)' is said to vary
directly with the value of `date_col', because for every change in the
value of `date_col', the value of the expression changes in a
consistent manner. The variance of the expression `YEAR(date_col)' with
respect to `date_col' is not quite as direct as that of
`TO_DAYS(date_col)', because not every possible change in `date_col'
produces an equivalent change in `YEAR(date_col)'. Even so,
`YEAR(date_col)' is a good candidate for a hashing function, because it
varies directly with a portion of `date_col' and there is no possible
change in `date_col' that produces a disproportionate change in
`YEAR(date_col)'.

By way of contrast, suppose that you have a column named `int_col'
whose type is *Note `INT': numeric-types. Now consider the expression
`POW(5-int_col,3) + 6'. This would be a poor choice for a hashing
function because a change in the value of `int_col' is not guaranteed
to produce a proportional change in the value of the expression.
Changing the value of `int_col' by a given amount can produce by widely
different changes in the value of the expression. For example, changing
`int_col' from `5' to `6' produces a change of `-1' in the value of the
expression, but changing the value of `int_col' from `6' to `7'
produces a change of `-7' in the expression value.

In other words, the more closely the graph of the column value _versus_
the value of the expression follows a straight line as traced by the
equation `y=Nx' where N is some nonzero constant, the better the
expression is suited to hashing. This has to do with the fact that the
more nonlinear an expression is, the more uneven the distribution of
data among the partitions it tends to produce.

In theory, pruning is also possible for expressions involving more than
one column value, but determining which of such expressions are
suitable can be quite difficult and time-consuming. For this reason,
the use of hashing expressions involving multiple columns is not
particularly recommended.

When `PARTITION BY HASH' is used, MySQL determines which partition of
NUM partitions to use based on the modulus of the result of the user
function. In other words, for an expression EXPR, the partition in
which the record is stored is partition number N, where `N = MOD(EXPR,
NUM)'. For example, suppose table `t1' is defined as follows, so that it
has 4 partitions:

     CREATE TABLE t1 (col1 INT, col2 CHAR(5), col3 DATE)
         PARTITION BY HASH( YEAR(col3) )
         PARTITIONS 4;

If you insert a record into `t1' whose `col3' value is `'2005-09-15'',
then the partition in which it is stored is determined as follows:

     MOD(YEAR('2005-09-01'),4)
     =  MOD(2005,4)
     =  1

MySQL 6.0 also supports a variant of `HASH' partitioning known as
_linear hashing_ which employs a more complex algorithm for determining
the placement of new rows inserted into the partitioned table. See
*Note partitioning-linear-hash::, for a description of this algorithm.

The user function is evaluated each time a record is inserted or
updated. It may also -- depending on the circumstances -- be evaluated
when records are deleted.

*Note*:

If a table to be partitioned has a `UNIQUE' key, then any columns
supplied as arguments to the `HASH' user function or to the `KEY''s
COLUMN_LIST must be part of that key.


File: manual.info,  Node: partitioning-linear-hash,  Prev: partitioning-hash,  Up: partitioning-hash

17.2.3.1 `LINEAR HASH' Partitioning
...................................

MySQL also supports linear hashing, which differs from regular hashing
in that linear hashing utilizes a linear powers-of-two algorithm
whereas regular hashing employs the modulus of the hashing function's
value.

Syntactically, the only difference between linear-hash partitioning and
regular hashing is the addition of the `LINEAR' keyword in the
`PARTITION BY' clause, as shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     )
     PARTITION BY LINEAR HASH( YEAR(hired) )
     PARTITIONS 4;

Given an expression EXPR, the partition in which the record is stored
when linear hashing is used is partition number N from among NUM
partitions, where N is derived according to the following algorithm:

  1. Find the next power of 2 greater than NUM. We call this value V;
     it can be calculated as:

          V = POWER(2, CEILING(LOG(2, NUM)))

     (For example, suppose that NUM is 13. Then `LOG(2,13)' is
     3.7004397181411.  `CEILING(3.7004397181411)' is 4, and V =
     `POWER(2,4)', which is 16.)

  2. Set N = F(COLUMN_LIST) & (V - 1).

  3. While N >= NUM:

        * Set V = CEIL(V / 2)

        * Set N = N & (V - 1)

For example, suppose that the table `t1', using linear hash
partitioning and having 6 partitions, is created using this statement:

     CREATE TABLE t1 (col1 INT, col2 CHAR(5), col3 DATE)
         PARTITION BY LINEAR HASH( YEAR(col3) )
         PARTITIONS 6;

Now assume that you want to insert two records into `t1' having the
`col3' column values `'2003-04-14'' and `'1998-10-19''. The partition
number for the first of these is determined as follows:

     V = POWER(2, CEILING( LOG(2,6) )) = 8
     N = YEAR('2003-04-14') & (8 - 1)
        = 2003 & 7
        = 3

     (_3 >= 6 is FALSE: record stored in partition #3_)

The number of the partition where the second record is stored is
calculated as shown here:

     V = 8
     N = YEAR('1998-10-19') & (8-1)
       = 1998 & 7
       = 6

     (_6 >= 6 is TRUE: additional step required_)

     N = 6 & CEILING(8 / 2)
       = 6 & 3
       = 2

     (_2 >= 6 is FALSE: record stored in partition #2_)

The advantage in partitioning by linear hash is that the adding,
dropping, merging, and splitting of partitions is made much faster,
which can be beneficial when dealing with tables containing extremely
large amounts (terabytes) of data. The disadvantage is that data is
less likely to be evenly distributed between partitions as compared
with the distribution obtained using regular hash partitioning.


File: manual.info,  Node: partitioning-key,  Next: partitioning-subpartitions,  Prev: partitioning-hash,  Up: partitioning-types

17.2.4 `KEY' Partitioning
-------------------------

Partitioning by key is similar to partitioning by hash, except that
where hash partitioning employs a user-defined expression, the hashing
function for key partitioning is supplied by the MySQL server. This
function is based on the same algorithm as `PASSWORD()'.

The syntax rules for `CREATE TABLE ... PARTITION BY KEY' are similar to
those for creating a table that is partitioned by hash. The major
differences are that:

   * `KEY' is used rather than `HASH'.

   * `KEY' takes only a list of one or more column names. The column or
     columns used as the partitioning key must comprise part or all of
     the table's primary key, if the table has one.

     `KEY' takes a list of zero or more column names. Where no column
     name is specified as the partitioning key, the table's primary key
     is used, if there is one. For example, the following *Note `CREATE
     TABLE': create-table. statement is valid in MySQL 6.0:

          CREATE TABLE k1 (
              id INT NOT NULL PRIMARY KEY,
              name VARCHAR(20)
          )
          PARTITION BY KEY()
          PARTITIONS 2;

     If there is no primary key but there is a unique key, then the
     unique key is used for the partitioning key:

          CREATE TABLE k1 (
              id INT NOT NULL,
              name VARCHAR(20),
              UNIQUE KEY (id)
          )
          PARTITION BY KEY()
          PARTITIONS 2;

     However, if the unique key column were not defined as `NOT NULL',
     then the previous statement would fail.

     In both of these cases, the partitioning key is the `id' column,
     even though it is not shown in the output of *Note `SHOW CREATE
     TABLE': show-create-table. or in the `PARTITION_EXPRESSION' column
     of the *Note `INFORMATION_SCHEMA.PARTITIONS': partitions-table.
     table.

     Unlike the case with other partitioning types, columns used for
     partitioning by `KEY' are not restricted to integer or `NULL'
     values. For example, the following *Note `CREATE TABLE':
     create-table. statement is valid:

          CREATE TABLE tm1 (
              s1 CHAR(32) PRIMARY KEY
          )
          PARTITION BY KEY(s1)
          PARTITIONS 10;

     The preceding statement would _not_ be valid, were a different
     partitioning type to be specified.

     *Note*:

     In this case, simply using `PARTITION BY KEY()' would also be
     valid and have the same effect as `PARTITION BY KEY(s1)', since
     `s1' is the table's primary key.

     For additional information about this issue, see *Note
     partitioning-limitations::.

     *Important*:

     For a key-partitioned table, you cannot execute an `ALTER TABLE
     DROP PRIMARY KEY', as doing so generates the error `ERROR 1466
     (HY000): Field in list of fields for partition function not found
     in table'.

It is also possible to partition a table by linear key. Here is a
simple example:

     CREATE TABLE tk (
         col1 INT NOT NULL,
         col2 CHAR(5),
         col3 DATE
     )
     PARTITION BY LINEAR KEY (col1)
     PARTITIONS 3;

Using `LINEAR' has the same effect on `KEY' partitioning as it does on
`HASH' partitioning, with the partition number being derived using a
powers-of-two algorithm rather than modulo arithmetic. See *Note
partitioning-linear-hash::, for a description of this algorithm and its
implications.


File: manual.info,  Node: partitioning-subpartitions,  Next: partitioning-handling-nulls,  Prev: partitioning-key,  Up: partitioning-types

17.2.5 Subpartitioning
----------------------

Subpartitioning -- also known as _composite partitioning_ -- is the
further division of each partition in a partitioned table. For example,
consider the following *Note `CREATE TABLE': create-table. statement:

     CREATE TABLE ts (id INT, purchased DATE)
         PARTITION BY RANGE( YEAR(purchased) )
         SUBPARTITION BY HASH( TO_DAYS(purchased) )
         SUBPARTITIONS 2 (
             PARTITION p0 VALUES LESS THAN (1990),
             PARTITION p1 VALUES LESS THAN (2000),
             PARTITION p2 VALUES LESS THAN MAXVALUE
         );

Table `ts' has 3 `RANGE' partitions. Each of these partitions -- `p0',
`p1', and `p2' -- is further divided into 2 subpartitions. In effect,
the entire table is divided into `3 * 2 = 6' partitions. However, due
to the action of the `PARTITION BY RANGE' clause, the first 2 of these
store only those records with a value less than 1990 in the `purchased'
column.

In MySQL 6.0, it is possible to subpartition tables that are
partitioned by `RANGE' or `LIST'. Subpartitions may use either `HASH'
or `KEY' partitioning.  This is also known as _composite partitioning_.

It is also possible to define subpartitions explicitly using
`SUBPARTITION' clauses to specify options for individual subpartitions.
For example, a more verbose fashion of creating the same table `ts' as
shown in the previous example would be:

     CREATE TABLE ts (id INT, purchased DATE)
         PARTITION BY RANGE( YEAR(purchased) )
         SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
             PARTITION p0 VALUES LESS THAN (1990) (
                 SUBPARTITION s0,
                 SUBPARTITION s1
             ),
             PARTITION p1 VALUES LESS THAN (2000) (
                 SUBPARTITION s2,
                 SUBPARTITION s3
             ),
             PARTITION p2 VALUES LESS THAN MAXVALUE (
                 SUBPARTITION s4,
                 SUBPARTITION s5
             )
         );

Some syntactical items of note:

   * Each partition must have the same number of subpartitions.

   * If you explicitly define any subpartitions using `SUBPARTITION' on
     any partition of a partitioned table, you must define them all. In
     other words, the following statement will fail:

          CREATE TABLE ts (id INT, purchased DATE)
              PARTITION BY RANGE( YEAR(purchased) )
              SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
                  PARTITION p0 VALUES LESS THAN (1990) (
                      SUBPARTITION s0,
                      SUBPARTITION s1
                  ),
                  PARTITION p1 VALUES LESS THAN (2000),
                  PARTITION p2 VALUES LESS THAN MAXVALUE (
                      SUBPARTITION s2,
                      SUBPARTITION s3
                  )
              );

     This statement would still fail even if it included a
     `SUBPARTITIONS 2' clause.

   * Each `SUBPARTITION' clause must include (at a minimum) a name for
     the subpartition. Otherwise, you may set any desired option for
     the subpartition or allow it to assume its default setting for
     that option.

   * Subpartition names must be unique across the entire table.  For
     example, the following *Note `CREATE TABLE': create-table.
     statement is valid in MySQL 6.0:

          CREATE TABLE ts (id INT, purchased DATE)
              PARTITION BY RANGE( YEAR(purchased) )
              SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
                  PARTITION p0 VALUES LESS THAN (1990) (
                      SUBPARTITION s0,
                      SUBPARTITION s1
                  ),
                  PARTITION p1 VALUES LESS THAN (2000) (
                      SUBPARTITION s2,
                      SUBPARTITION s3
                  ),
                  PARTITION p2 VALUES LESS THAN MAXVALUE (
                      SUBPARTITION s4,
                      SUBPARTITION s5
                  )
              );

Subpartitions can be used with especially large tables to distribute
data and indexes across many disks. Suppose that you have 6 disks
mounted as `/disk0', `/disk1', `/disk2', and so on. Now consider the
following example:

     CREATE TABLE ts (id INT, purchased DATE)
         PARTITION BY RANGE( YEAR(purchased) )
         SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
             PARTITION p0 VALUES LESS THAN (1990) (
                 SUBPARTITION s0
                     DATA DIRECTORY = '/disk0/data'
                     INDEX DIRECTORY = '/disk0/idx',
                 SUBPARTITION s1
                     DATA DIRECTORY = '/disk1/data'
                     INDEX DIRECTORY = '/disk1/idx'
             ),
             PARTITION p1 VALUES LESS THAN (2000) (
                 SUBPARTITION s2
                     DATA DIRECTORY = '/disk2/data'
                     INDEX DIRECTORY = '/disk2/idx',
                 SUBPARTITION s3
                     DATA DIRECTORY = '/disk3/data'
                     INDEX DIRECTORY = '/disk3/idx'
             ),
             PARTITION p2 VALUES LESS THAN MAXVALUE (
                 SUBPARTITION s4
                     DATA DIRECTORY = '/disk4/data'
                     INDEX DIRECTORY = '/disk4/idx',
                 SUBPARTITION s5
                     DATA DIRECTORY = '/disk5/data'
                     INDEX DIRECTORY = '/disk5/idx'
             )
         );

In this case, a separate disk is used for the data and for the indexes
of each `RANGE'. Many other variations are possible; another example
might be:

     CREATE TABLE ts (id INT, purchased DATE)
         PARTITION BY RANGE(YEAR(purchased))
         SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
             PARTITION p0 VALUES LESS THAN (1990) (
                 SUBPARTITION s0a
                     DATA DIRECTORY = '/disk0'
                     INDEX DIRECTORY = '/disk1',
                 SUBPARTITION s0b
                     DATA DIRECTORY = '/disk2'
                     INDEX DIRECTORY = '/disk3'
             ),
             PARTITION p1 VALUES LESS THAN (2000) (
                 SUBPARTITION s1a
                     DATA DIRECTORY = '/disk4/data'
                     INDEX DIRECTORY = '/disk4/idx',
                 SUBPARTITION s1b
                     DATA DIRECTORY = '/disk5/data'
                     INDEX DIRECTORY = '/disk5/idx'
             ),
             PARTITION p2 VALUES LESS THAN MAXVALUE (
                 SUBPARTITION s2a,
                 SUBPARTITION s2b
             )
         );

Here, the storage is as follows:

   * Rows with `purchased' dates from before 1990 take up a vast amount
     of space, so are split up 4 ways, with a separate disk dedicated
     to the data and to the indexes for each of the two subpartitions
     (`s0a' and `s0b') making up partition `p0'. In other words:

        * The data for subpartition `s0a' is stored on `/disk0'.

        * The indexes for subpartition `s0a' are stored on `/disk1'.

        * The data for subpartition `s0b' is stored on `/disk2'.

        * The indexes for subpartition `s0b' are stored on `/disk3'.

   * Rows containing dates ranging from 1990 to 1999 (partition `p1')
     do not require as much room as those from before 1990. These are
     split between 2 disks (`/disk4' and `/disk5') rather than 4 disks
     as with the legacy records stored in `p0':

        * Data and indexes belonging to `p1''s first subpartition
          (`s1a') are stored on `/disk4' -- the data in `/disk4/data',
          and the indexes in `/disk4/idx'.

        * Data and indexes belonging to `p1''s second subpartition
          (`s1b') are stored on `/disk5' -- the data in `/disk5/data',
          and the indexes in `/disk5/idx'.

   * Rows reflecting dates from the year 2000 to the present (partition
     `p2') do not take up as much space as required by either of the
     two previous ranges.  Currently, it is sufficient to store all of
     these in the default location.

     In future, when the number of purchases for the decade beginning
     with the year 2000 grows to a point where the default location no
     longer provides sufficient space, the corresponding rows can be
     moved using an `ALTER TABLE ... REORGANIZE PARTITION' statement.
     See *Note partitioning-management::, for an explanation of how
     this can be done.

The `DATA DIRECTORY' and `INDEX DIRECTORY' options are disallowed when
the `NO_DIR_IN_CREATE' server SQL mode is in effect. This is true for
partitions and subpartitions.


File: manual.info,  Node: partitioning-handling-nulls,  Prev: partitioning-subpartitions,  Up: partitioning-types

17.2.6 How MySQL Partitioning Handles `NULL'
--------------------------------------------

Partitioning in MySQL does nothing to disallow `NULL' as the value of a
partitioning expression, whether it is a column value or the value of a
user-supplied expression. Even though it is permitted to use `NULL' as
the value of an expression that must otherwise yield an integer, it is
important to keep in mind that `NULL' is not a number. MySQL's
partitioning implementation treats `NULL' as being less than any
non-`NULL' value, just as `ORDER BY' does.

This means that treatment of `NULL' varies between partitioning of
different types, and may produce behavior which you do not expect if
you are not prepared for it.  This being the case, we discuss in this
section how each MySQL partitioning type handles `NULL' values when
determining the partition in which a row should be stored, and provide
examples for each.

Handling of `NULL' with `RANGE' partitioning

If you insert a row into a table partitioned by `RANGE' such that the
column value used to determine the partition is `NULL', the row is
inserted into the lowest partition. For example, consider these two
tables in a database named `p', created as follows:

     mysql> CREATE TABLE t1 (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY RANGE(c1) (
         ->     PARTITION p0 VALUES LESS THAN (0),
         ->     PARTITION p1 VALUES LESS THAN (10),
         ->     PARTITION p2 VALUES LESS THAN MAXVALUE
         -> );
     Query OK, 0 rows affected (0.09 sec)

     mysql> CREATE TABLE t2 (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY RANGE(c1) (
         ->     PARTITION p0 VALUES LESS THAN (-5),
         ->     PARTITION p1 VALUES LESS THAN (0),
         ->     PARTITION p2 VALUES LESS THAN (10),
         ->     PARTITION p3 VALUES LESS THAN MAXVALUE
         -> );
     Query OK, 0 rows affected (0.09 sec)

You can see the partitions created by these two *Note `CREATE TABLE':
create-table. statements using the following query against the *Note
`PARTITIONS': partitions-table. table in the `INFORMATION_SCHEMA'
database:

     mysql> SELECT TABLE_NAME, PARTITION_NAME, TABLE_ROWS, AVG_ROW_LENGTH, DATA_LENGTH
          >   FROM INFORMATION_SCHEMA.PARTITIONS
          >   WHERE TABLE_SCHEMA = 'p' AND TABLE_NAME LIKE 't_';
     +------------+----------------+------------+----------------+-------------+
     | TABLE_NAME | PARTITION_NAME | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH |
     +------------+----------------+------------+----------------+-------------+
     | t1         | p0             |          0 |              0 |           0 |
     | t1         | p1             |          0 |              0 |           0 |
     | t1         | p2             |          0 |              0 |           0 |
     | t2         | p0             |          0 |              0 |           0 |
     | t2         | p1             |          0 |              0 |           0 |
     | t2         | p2             |          0 |              0 |           0 |
     | t2         | p3             |          0 |              0 |           0 |
     +------------+----------------+------------+----------------+-------------+
     7 rows in set (0.00 sec)

(For more information about this table, see *Note partitions-table::.)
Now let us populate each of these tables with a single row containing a
`NULL' in the column used as the partitioning key, and verify that the
rows were inserted using a pair of *Note `SELECT': select. statements:

     mysql> INSERT INTO t1 VALUES (NULL, 'mothra');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO t2 VALUES (NULL, 'mothra');
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT * FROM t1;
     +------+--------+
     | id   | name   |
     +------+--------+
     | NULL | mothra |
     +------+--------+
     1 row in set (0.00 sec)

     mysql> SELECT * FROM t2;
     +------+--------+
     | id   | name   |
     +------+--------+
     | NULL | mothra |
     +------+--------+
     1 row in set (0.00 sec)

You can see which partitions are used to store the inserted rows by
rerunning the previous query against *Note
`INFORMATION_SCHEMA.PARTITIONS': partitions-table. and inspecting the
output:

     mysql> SELECT TABLE_NAME, PARTITION_NAME, TABLE_ROWS, AVG_ROW_LENGTH, DATA_LENGTH
          >   FROM INFORMATION_SCHEMA.PARTITIONS
          >   WHERE TABLE_SCHEMA = 'p' AND TABLE_NAME LIKE 't_';
     +------------+----------------+------------+----------------+-------------+
     | TABLE_NAME | PARTITION_NAME | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH |
     +------------+----------------+------------+----------------+-------------+
     _| t1         | p0             |          1 |             20 |          20 |_
     | t1         | p1             |          0 |              0 |           0 |
     | t1         | p2             |          0 |              0 |           0 |
     _| t2         | p0             |          1 |             20 |          20 |_
     | t2         | p1             |          0 |              0 |           0 |
     | t2         | p2             |          0 |              0 |           0 |
     | t2         | p3             |          0 |              0 |           0 |
     +------------+----------------+------------+----------------+-------------+
     7 rows in set (0.01 sec)

You can also demonstrate that these rows were stored in the lowest
partition of each table by dropping these partitions, and then
re-running the *Note `SELECT': select.  statements:

     mysql> ALTER TABLE t1 DROP PARTITION p0;
     Query OK, 0 rows affected (0.16 sec)

     mysql> ALTER TABLE t2 DROP PARTITION p0;
     Query OK, 0 rows affected (0.16 sec)

     mysql> SELECT * FROM t1;
     Empty set (0.00 sec)

     mysql> SELECT * FROM t2;
     Empty set (0.00 sec)

(For more information on `ALTER TABLE ... DROP PARTITION', see *Note
alter-table::.)

`NULL' is also treated in this way for partitioning expressions that
use SQL functions. Suppose that we define a table using a *Note `CREATE
TABLE': create-table. statement such as this one:

     CREATE TABLE tndate (
         id INT,
         dt DATE
     )
     PARTITION BY RANGE( YEAR(dt) ) (
         PARTITION p0 VALUES LESS THAN (1990),
         PARTITION p1 VALUES LESS THAN (2000),
         PARTITION p2 VALUES LESS THAN MAXVALUE
     );

As with other MySQL functions, `YEAR(NULL)' returns `NULL'. A row with
a `dt' column value of `NULL' is treated as though the partitioning
expression evaluated to a value less than any other value, and so is
inserted into partition `p0'.

Handling of `NULL' with `LIST' partitioning

A table that is partitioned by `LIST' admits `NULL' values if and only
if one of its partitions is defined using that value-list that contains
`NULL'. The converse of this is that a table partitioned by `LIST'
which does not explicitly use `NULL' in a value list rejects rows
resulting in a `NULL' value for the partitioning expression, as shown
in this example:

     mysql> CREATE TABLE ts1 (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY LIST(c1) (
         ->     PARTITION p0 VALUES IN (0, 3, 6),
         ->     PARTITION p1 VALUES IN (1, 4, 7),
         ->     PARTITION p2 VALUES IN (2, 5, 8)
         -> );
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO ts1 VALUES (9, 'mothra');
     `ERROR 1504 (HY000): Table has no partition for value 9'

     mysql> INSERT INTO ts1 VALUES (NULL, 'mothra');
     `ERROR 1504 (HY000): Table has no partition for value NULL'

Only rows having a `c1' value between `0' and `8' inclusive can be
inserted into `ts1'. `NULL' falls outside this range, just like the
number `9'. We can create tables `ts2' and `ts3' having value lists
containing `NULL', as shown here:

     mysql> CREATE TABLE ts2 (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY LIST(c1) (
         ->     PARTITION p0 VALUES IN (0, 3, 6),
         ->     PARTITION p1 VALUES IN (1, 4, 7),
         ->     PARTITION p2 VALUES IN (2, 5, 8),
         ->     PARTITION p3 VALUES IN (NULL)
         -> );
     Query OK, 0 rows affected (0.01 sec)

     mysql> CREATE TABLE ts3 (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY LIST(c1) (
         ->     PARTITION p0 VALUES IN (0, 3, 6),
         ->     PARTITION p1 VALUES IN (1, 4, 7, NULL),
         ->     PARTITION p2 VALUES IN (2, 5, 8)
         -> );
     Query OK, 0 rows affected (0.01 sec)

When defining value lists for partitioning, you can (and should) treat
`NULL' just as you would any other value. For example, both `VALUES IN
(NULL)' and `VALUES IN (1, 4, 7, NULL)' are valid, as are `VALUES IN
(1, NULL, 4, 7)', `VALUES IN (NULL, 1, 4, 7)', and so on. You can
insert a row having `NULL' for column `c1' into each of the tables
`ts2' and `ts3':

     mysql> INSERT INTO ts2 VALUES (NULL, 'mothra');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO ts3 VALUES (NULL, 'mothra');
     Query OK, 1 row affected (0.00 sec)

By issuing the appropriate query against *Note
`INFORMATION_SCHEMA.PARTITIONS': partitions-table, you can determine
which partitions were used to store the rows just inserted (we assume,
as in the previous examples, that the partitioned tables were created
in the `p' database):

     mysql> SELECT TABLE_NAME, PARTITION_NAME, TABLE_ROWS, AVG_ROW_LENGTH, DATA_LENGTH
          >   FROM INFORMATION_SCHEMA.PARTITIONS
          >   WHERE TABLE_SCHEMA = 'p' AND TABLE_NAME LIKE 'ts_';
     +------------+----------------+------------+----------------+-------------+
     | TABLE_NAME | PARTITION_NAME | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH |
     +------------+----------------+------------+----------------+-------------+
     | ts2        | p0             |          0 |              0 |           0 |
     | ts2        | p1             |          0 |              0 |           0 |
     | ts2        | p2             |          0 |              0 |           0 |
     _| ts2        | p3             |          1 |             20 |          20 |_
     | ts3        | p0             |          0 |              0 |           0 |
     _| ts3        | p1             |          1 |             20 |          20 |_
     | ts3        | p2             |          0 |              0 |           0 |
     +------------+----------------+------------+----------------+-------------+
     7 rows in set (0.01 sec)

As shown earlier in this section, you can also verify which partitions
were used for storing the rows by deleting these partitions and then
performing a *Note `SELECT': select.

Handling of `NULL' with `HASH' and `KEY' partitioning

`NULL' is handled somewhat differently for tables partitioned by `HASH'
or `KEY'. In these cases, any partition expression that yields a `NULL'
value is treated as though its return value were zero. We can verify
this behavior by examining the effects on the file system of creating a
table partitioned by `HASH' and populating it with a record containing
appropriate values.  Suppose that you have a table `th' (also in the
`p' database) created using the following statement:

     mysql> CREATE TABLE th (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY HASH(c1)
         -> PARTITIONS 2;
     Query OK, 0 rows affected (0.00 sec)

The partitions belonging to this table can be viewed like this:

     mysql> SELECT TABLE_NAME,PARTITION_NAME,TABLE_ROWS,AVG_ROW_LENGTH,DATA_LENGTH
          >   FROM INFORMATION_SCHEMA.PARTITIONS
          >   WHERE TABLE_SCHEMA = 'p' AND TABLE_NAME ='th';
     +------------+----------------+------------+----------------+-------------+
     | TABLE_NAME | PARTITION_NAME | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH |
     +------------+----------------+------------+----------------+-------------+
     | th         | p0             |          0 |              0 |           0 |
     | th         | p1             |          0 |              0 |           0 |
     +------------+----------------+------------+----------------+-------------+
     2 rows in set (0.00 sec)

Note that TABLE_ROWS for each partition is 0. Now insert two rows into
`th' whose `c1' column values are `NULL' and 0, and verify that these
rows were inserted:

     mysql> INSERT INTO th VALUES (NULL, 'mothra'), (0, 'gigan');
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT * FROM th;
     +------+---------+
     | c1   | c2      |
     +------+---------+
     | NULL | mothra  |
     +------+---------+
     |    0 | gigan   |
     +------+---------+
     2 rows in set (0.01 sec)

Recall that for any integer N, the value of `NULL MOD N' is always
`NULL'. For tables that are partitioned by `HASH' or `KEY', this result
is treated for determining the correct partition as `0'. Checking the
*Note `INFORMATION_SCHEMA.PARTITIONS': partitions-table.  table once
again, we can see that both rows were inserted into partition `p0':

     mysql> SELECT TABLE_NAME, PARTITION_NAME, TABLE_ROWS, AVG_ROW_LENGTH, DATA_LENGTH
          >   FROM INFORMATION_SCHEMA.PARTITIONS
          >   WHERE TABLE_SCHEMA = 'p' AND TABLE_NAME ='th';
     +------------+----------------+------------+----------------+-------------+
     | TABLE_NAME | PARTITION_NAME | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH |
     +------------+----------------+------------+----------------+-------------+
     _| th         | p0             |          2 |             20 |          20 |_
     | th         | p1             |          0 |              0 |           0 |
     +------------+----------------+------------+----------------+-------------+
     2 rows in set (0.00 sec)

If you repeat this example using `PARTITION BY KEY' in place of
`PARTITION BY HASH' in the definition of the table, you can verify
easily that `NULL' is also treated like 0 for this type of partitioning
as well.


File: manual.info,  Node: partitioning-management,  Next: partitioning-pruning,  Prev: partitioning-types,  Up: partitioning

17.3 Partition Management
=========================

* Menu:

* partitioning-management-range-list::  Management of `RANGE' and `LIST' Partitions
* partitioning-management-hash-key::  Management of `HASH' and `KEY' Partitions
* partitioning-maintenance::     Maintenance of Partitions
* partitioning-info::            Obtaining Information About Partitions

MySQL 6.0 provides a number of ways to modify partitioned tables. It is
possible to add, drop, redefine, merge, or split existing partitions.
All of these actions can be carried out using the partitioning
extensions to the *Note `ALTER TABLE': alter-table. command (see *Note
alter-table::, for syntax definitions). There are also ways to obtain
information about partitioned tables and partitions. We discuss these
topics in the sections that follow.

   * For information about partition management in tables partitioned
     by `RANGE' or `LIST', see *Note
     partitioning-management-range-list::.

   * For a discussion of managing `HASH' and `KEY' partitions, see
     *Note partitioning-management-hash-key::.

   * See *Note partitioning-info::, for a discussion of mechanisms
     provided in MySQL 6.0 for obtaining information about partitioned
     tables and partitions.

   * For a discussion of performing maintenance operations on
     partitions, see *Note partitioning-maintenance::.

*Note*:

In MySQL 6.0, all partitions of a partitioned table must have the same
number of subpartitions, and it is not possible to change the
subpartitioning once the table has been created.

To change a table's partitioning scheme, it is necessary only to use
the *Note `ALTER TABLE': alter-table. command with a PARTITION_OPTIONS
clause. This clause has the same syntax as that as used with *Note
`CREATE TABLE': create-table. for creating a partitioned table, and
always begins with the keywords `PARTITION BY'. For example, suppose
that you have a table partitioned by range using the following *Note
`CREATE TABLE': create-table. statement:

     CREATE TABLE trb3 (id INT, name VARCHAR(50), purchased DATE)
         PARTITION BY RANGE( YEAR(purchased) ) (
             PARTITION p0 VALUES LESS THAN (1990),
             PARTITION p1 VALUES LESS THAN (1995),
             PARTITION p2 VALUES LESS THAN (2000),
             PARTITION p3 VALUES LESS THAN (2005)
         );

To repartition this table so that it is partitioned by key into two
partitions using the `id' column value as the basis for the key, you
can use this statement:

     ALTER TABLE trb3 PARTITION BY KEY(id) PARTITIONS 2;

This has the same effect on the structure of the table as dropping the
table and re-creating it using `CREATE TABLE trb3 PARTITION BY KEY(id)
PARTITIONS 2;'.

`ALTER TABLE ... ENGINE = ...' changes only the storage engine used by
the table, and leaves the table's partitioning scheme intact. Use
`ALTER TABLE ... REMOVE PARTITIONING' to remove a table's partitioning.
See *Note alter-table::.

*Important*:

Only a single `PARTITION BY', `ADD PARTITION', `DROP PARTITION',
`REORGANIZE PARTITION', or `COALESCE PARTITION' clause can be used in a
given *Note `ALTER TABLE': alter-table. statement. If you (for example)
wish to drop a partition and reorganize a table's remaining partitions,
you must do so in two separate *Note `ALTER TABLE': alter-table.
statements (one using `DROP PARTITION' and then a second one using
`REORGANIZE PARITITIONS').


File: manual.info,  Node: partitioning-management-range-list,  Next: partitioning-management-hash-key,  Prev: partitioning-management,  Up: partitioning-management

17.3.1 Management of `RANGE' and `LIST' Partitions
--------------------------------------------------

Range and list partitions are very similar with regard to how the
adding and dropping of partitions are handled. For this reason we
discuss the management of both sorts of partitioning in this section.
For information about working with tables that are partitioned by hash
or key, see *Note partitioning-management-hash-key::. Dropping a
`RANGE' or `LIST' partition is more straightforward than adding one, so
we discuss this first.

Dropping a partition from a table that is partitioned by either `RANGE'
or by `LIST' can be accomplished using the *Note `ALTER TABLE':
alter-table. statement with a `DROP PARTITION' clause. Here is a very
basic example, which supposes that you have already created a table
which is partitioned by range and then populated with 10 records using
the following *Note `CREATE TABLE': create-table. and *Note `INSERT':
insert. statements:

     mysql> CREATE TABLE tr (id INT, name VARCHAR(50), purchased DATE)
         ->     PARTITION BY RANGE( YEAR(purchased) ) (
         ->         PARTITION p0 VALUES LESS THAN (1990),
         ->         PARTITION p1 VALUES LESS THAN (1995),
         ->         PARTITION p2 VALUES LESS THAN (2000),
         ->         PARTITION p3 VALUES LESS THAN (2005)
         ->     );
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO tr VALUES
         ->     (1, 'desk organiser', '2003-10-15'),
         ->     (2, 'CD player', '1993-11-05'),
         ->     (3, 'TV set', '1996-03-10'),
         ->     (4, 'bookcase', '1982-01-10'),
         ->     (5, 'exercise bike', '2004-05-09'),
         ->     (6, 'sofa', '1987-06-05'),
         ->     (7, 'popcorn maker', '2001-11-22'),
         ->     (8, 'aquarium', '1992-08-04'),
         ->     (9, 'study desk', '1984-09-16'),
         ->     (10, 'lava lamp', '1998-12-25');
     Query OK, 10 rows affected (0.01 sec)

You can see which items should have been inserted into partition `p2'
as shown here:

     mysql> SELECT * FROM tr
         -> WHERE purchased BETWEEN '1995-01-01' AND '1999-12-31';
     +------+-----------+------------+
     | id   | name      | purchased  |
     +------+-----------+------------+
     |    3 | TV set    | 1996-03-10 |
     |   10 | lava lamp | 1998-12-25 |
     +------+-----------+------------+
     2 rows in set (0.00 sec)

To drop the partition named `p2', execute the following command:

     mysql> ALTER TABLE tr DROP PARTITION p2;
     Query OK, 0 rows affected (0.03 sec)

It is very important to remember that, _when you drop a partition, you
also delete all the data that was stored in that partition_. You can
see that this is the case by re-running the previous *Note `SELECT':
select.  query:

     mysql> SELECT * FROM tr WHERE purchased
         -> BETWEEN '1995-01-01' AND '1999-12-31';
     Empty set (0.00 sec)

Because of this, you must have the `DROP' privilege for a table before
you can execute `ALTER TABLE ... DROP PARTITION' on that table.

If you wish to drop all data from all partitions while preserving the
table definition and its partitioning scheme, use the *Note `TRUNCATE
TABLE': truncate. command. (See *Note truncate::.)

If you intend to change the partitioning of a table _without_ losing
data, use `ALTER TABLE ... REORGANIZE PARTITION' instead. See below or
in *Note alter-table::, for information about `REORGANIZE PARTITION'.

If you now execute a *Note `SHOW CREATE TABLE': show-create-table.
command, you can see how the partitioning makeup of the table has been
changed:

     mysql> SHOW CREATE TABLE tr\G
     *************************** 1. row ***************************
            Table: tr
     Create Table: CREATE TABLE `tr` (
       `id` int(11) default NULL,
       `name` varchar(50) default NULL,
       `purchased` date default NULL
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1
     PARTITION BY RANGE ( YEAR(purchased) ) (
       PARTITION p0 VALUES LESS THAN (1990) ENGINE = MyISAM,
       PARTITION p1 VALUES LESS THAN (1995) ENGINE = MyISAM,
       PARTITION p3 VALUES LESS THAN (2005) ENGINE = MyISAM
     )
     1 row in set (0.01 sec)

When you insert new rows into the changed table with `purchased' column
values between `'1995-01-01'' and `'2004-12-31'' inclusive, those rows
will be stored in partition `p3'. You can verify this as follows:

     mysql> INSERT INTO tr VALUES (11, 'pencil holder', '1995-07-12');
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT * FROM tr WHERE purchased
         -> BETWEEN '1995-01-01' AND '2004-12-31';
     +------+----------------+------------+
     | id   | name           | purchased  |
     +------+----------------+------------+
     |   11 | pencil holder  | 1995-07-12 |
     |    1 | desk organiser | 2003-10-15 |
     |    5 | exercise bike  | 2004-05-09 |
     |    7 | popcorn maker  | 2001-11-22 |
     +------+----------------+------------+
     4 rows in set (0.00 sec)

     mysql> ALTER TABLE tr DROP PARTITION p3;
     Query OK, 0 rows affected (0.03 sec)

     mysql> SELECT * FROM tr WHERE purchased
         -> BETWEEN '1995-01-01' AND '2004-12-31';
     Empty set (0.00 sec)

Note that the number of rows dropped from the table as a result of
`ALTER TABLE ... DROP PARTITION' is not reported by the server as it
would be by the equivalent *Note `DELETE': delete. query.

Dropping `LIST' partitions uses exactly the same `ALTER TABLE ... DROP
PARTITION' syntax as used for dropping `RANGE' partitions. However,
there is one important difference in the effect this has on your use of
the table afterward: You can no longer insert into the table any rows
having any of the values that were included in the value list defining
the deleted partition. (See *Note partitioning-list::, for an example.)

To add a new range or list partition to a previously partitioned table,
use the `ALTER TABLE ... ADD PARTITION' statement. For tables which are
partitioned by `RANGE', this can be used to add a new range to the end
of the list of existing partitions. For example, suppose that you have
a partitioned table containing membership data for your organisation,
which is defined as follows:

     CREATE TABLE members (
         id INT,
         fname VARCHAR(25),
         lname VARCHAR(25),
         dob DATE
     )
     PARTITION BY RANGE( YEAR(dob) ) (
         PARTITION p0 VALUES LESS THAN (1970),
         PARTITION p1 VALUES LESS THAN (1980),
         PARTITION p2 VALUES LESS THAN (1990)
     );

Suppose further that the minimum age for members is 16. As the calendar
approaches the end of 2005, you realize that you will soon be admitting
members who were born in 1990 (and later in years to come). You can
modify the `members' table to accommodate new members born in the years
1990-1999 as shown here:

     ALTER TABLE ADD PARTITION (PARTITION p3 VALUES LESS THAN (2000));

*Important*:

With tables that are partitioned by range, you can use `ADD PARTITION'
to add new partitions to the high end of the partitions list only.
Trying to add a new partition in this manner between or before existing
partitions will result in an error as shown here:

     mysql> ALTER TABLE members
          >     ADD PARTITION (
          >     PARTITION p3 VALUES LESS THAN (1960));
     ERROR 1463 (HY000): VALUES LESS THAN value must be strictly »
        increasing for each partition

In a similar fashion, you can add new partitions to a table that is
partitioned by `LIST'. For example, given a table defined like so:

     CREATE TABLE tt (
         id INT,
         data INT
     )
     PARTITION BY LIST(data) (
         PARTITION p0 VALUES IN (5, 10, 15),
         PARTITION p1 VALUES IN (6, 12, 18)
     );

You can add a new partition in which to store rows having the `data'
column values `7', `14', and `21' as shown:

     ALTER TABLE tt ADD PARTITION (PARTITION p2 VALUES IN (7, 14, 21));

Note that you _cannot_ add a new `LIST' partition encompassing any
values that are already included in the value list of an existing
partition.  If you attempt to do so, an error will result:

     mysql> ALTER TABLE tt ADD PARTITION
          >     (PARTITION np VALUES IN (4, 8, 12));
     ERROR 1465 (HY000): Multiple definition of same constant »
                         in list partitioning

Because any rows with the `data' column value `12' have already been
assigned to partition `p1', you cannot create a new partition on table
`tt' that includes `12' in its value list. To accomplish this, you
could drop `p1', and add `np' and then a new `p1' with a modified
definition. However, as discussed earlier, this would result in the
loss of all data stored in `p1' -- and it is often the case that this
is not what you really want to do. Another solution might appear to be
to make a copy of the table with the new partitioning and to copy the
data into it using `CREATE TABLE ... SELECT ...', then drop the old
table and rename the new one, but this could be very time-consuming when
dealing with a large amounts of data. This also might not be feasible
in situations where high availability is a requirement.

You can add multiple partitions in a single `ALTER TABLE ... ADD
PARTITION' statement as shown here:

     CREATE TABLE employees (
       id INT NOT NULL,
       fname VARCHAR(50) NOT NULL,
       lname VARCHAR(50) NOT NULL,
       hired DATE NOT NULL
     )
     PARTITION BY RANGE( YEAR(hired) ) (
       PARTITION p1 VALUES LESS THAN (1991),
       PARTITION p2 VALUES LESS THAN (1996),
       PARTITION p3 VALUES LESS THAN (2001),
       PARTITION p4 VALUES LESS THAN (2005)
     );

     ALTER TABLE employees ADD PARTITION (
         PARTITION p5 VALUES LESS THAN (2010),
         PARTITION p6 VALUES LESS THAN MAXVALUE
     );

Fortunately, MySQL's partitioning implementation provides ways to
redefine partitions without losing data. Let us look first at a couple
of simple examples involving `RANGE' partitioning. Recall the `members'
table which is now defined as shown here:

     mysql> SHOW CREATE TABLE members\G
     *************************** 1. row ***************************
            Table: members
     Create Table: CREATE TABLE `members` (
       `id` int(11) default NULL,
       `fname` varchar(25) default NULL,
       `lname` varchar(25) default NULL,
       `dob` date default NULL
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1
     PARTITION BY RANGE ( YEAR(dob) ) (
       PARTITION p0 VALUES LESS THAN (1970) ENGINE = MyISAM,
       PARTITION p1 VALUES LESS THAN (1980) ENGINE = MyISAM,
       PARTITION p2 VALUES LESS THAN (1990) ENGINE = MyISAM.
       PARTITION p3 VALUES LESS THAN (2000) ENGINE = MyISAM
     )

Suppose that you would like to move all rows representing members born
before 1960 into a separate partition. As we have already seen, this
cannot be done using `ALTER TABLE ...  ADD PARTITION'. However, you can
use another partition-related extension to *Note `ALTER TABLE':
alter-table. in order to accomplish this:

     ALTER TABLE members REORGANIZE PARTITION p0 INTO (
         PARTITION s0 VALUES LESS THAN (1960),
         PARTITION s1 VALUES LESS THAN (1970)
     );

In effect, this command splits partition `p0' into two new partitions
`s0' and `s1'. It also moves the data that was stored in `p0' into the
new partitions according to the rules embodied in the two `PARTITION
... VALUES ...' clauses, so that `s0' contains only those records for
which `YEAR(dob)' is less than 1960 and `s1' contains those rows in
which `YEAR(dob)' is greater than or equal to 1960 but less than 1970.

A `REORGANIZE PARTITION' clause may also be used for merging adjacent
partitions. You can return the `members' table to its previous
partitioning as shown here:

     ALTER TABLE members REORGANIZE PARTITION s0,s1 INTO (
         PARTITION p0 VALUES LESS THAN (1970)
     );

No data is lost in splitting or merging partitions using `REORGANIZE
PARTITION'. In executing the above statement, MySQL moves all of the
records that were stored in partitions `s0' and `s1' into partition
`p0'.

The general syntax for `REORGANIZE PARTITION' is:

     ALTER TABLE TBL_NAME
         REORGANIZE PARTITION PARTITION_LIST
         INTO (PARTITION_DEFINITIONS);

Here, TBL_NAME is the name of the partitioned table, and PARTITION_LIST
is a comma-separated list of names of one or more existing partitions
to be changed.  PARTITION_DEFINITIONS is a comma-separated list of new
partition definitions, which follow the same rules as for the
PARTITION_DEFINITIONS list used in *Note `CREATE TABLE': create-table.
(see *Note create-table::). It should be noted that you are not limited
to merging several partitions into one, or to splitting one partition
into many, when using `REORGANIZE PARTITION'. For example, you can
reorganize all four partitions of the `members' table into two, as
follows:

     ALTER TABLE members REORGANIZE PARTITION p0,p1,p2,p3 INTO (
         PARTITION m0 VALUES LESS THAN (1980),
         PARTITION m1 VALUES LESS THAN (2000)
     );

You can also use `REORGANIZE PARTITION' with tables that are
partitioned by `LIST'. Let us return to the problem of adding a new
partition to the list-partitioned `tt' table and failing because the
new partition had a value that was already present in the value-list of
one of the existing partitions. We can handle this by adding a
partition that contains only non-conflicting values, and then
reorganizing the new partition and the existing one so that the value
which was stored in the existing one is now moved to the new one:

     ALTER TABLE tt ADD PARTITION (PARTITION np VALUES IN (4, 8));
     ALTER TABLE tt REORGANIZE PARTITION p1,np INTO (
         PARTITION p1 VALUES IN (6, 18),
         PARTITION np VALUES in (4, 8, 12)
     );

Here are some key points to keep in mind when using `ALTER TABLE ...
REORGANIZE PARTITION' to repartition tables that are partitioned by
`RANGE' or `LIST':

   * The `PARTITION' clauses used to determine the new partitioning
     scheme are subject to the same rules as those used with a *Note
     `CREATE TABLE': create-table. statement.

     Most importantly, you should remember that the new partitioning
     scheme cannot have any overlapping ranges (applies to tables
     partitioned by `RANGE') or sets of values (when reorganizing
     tables partitioned by `LIST').

   * The combination of partitions in the PARTITION_DEFINITIONS list
     should account for the same range or set of values overall as the
     combined partitions named in the PARTITION_LIST.

     For instance, in the `members' table used as an example in this
     section, partitions `p1' and `p2' together cover the years 1980
     through 1999. Therefore, any reorganization of these two
     partitions should cover the same range of years overall.

   * For tables partitioned by `RANGE', you can reorganize only
     adjacent partitions; you cannot skip over range partitions.

     For instance, you could not reorganize the `members' table used as
     an example in this section using a statement beginning with `ALTER
     TABLE members REORGANIZE PARTITION p0,p2 INTO ...' because `p0'
     covers the years prior to 1970 and `p2' the years from 1990
     through 1999 inclusive, and thus the two are not adjacent
     partitions.

   * You cannot use `REORGANIZE PARTITION' to change the table's
     partitioning type; that is, you cannot (for example) change
     `RANGE' partitions to `HASH' partitions or _vice versa_. You also
     cannot use this command to change the partitioning expression or
     column. To accomplish either of these tasks without dropping and
     re-creating the table, you can use `ALTER TABLE ... PARTITION BY
     ...'. For example:

          ALTER TABLE members
              PARTITION BY HASH( YEAR(dob) )
              PARTITIONS 8;


File: manual.info,  Node: partitioning-management-hash-key,  Next: partitioning-maintenance,  Prev: partitioning-management-range-list,  Up: partitioning-management

17.3.2 Management of `HASH' and `KEY' Partitions
------------------------------------------------

Tables which are partitioned by hash or by key are very similar to one
another with regard to making changes in a partitioning setup, and both
differ in a number of ways from tables which have been partitioned by
range or list. For that reason, this section addresses the modification
of tables partitioned by hash or by key only. For a discussion of
adding and dropping of partitions of tables that are partitioned by
range or list, see *Note partitioning-management-range-list::.

You cannot drop partitions from tables that are partitioned by `HASH'
or `KEY' in the same way that you can from tables that are partitioned
by `RANGE' or `LIST'. However, you can merge `HASH' or `KEY' partitions
using the `ALTER TABLE ... COALESCE PARTITION' command. For example,
suppose that you have a table containing data about clients, which is
divided into twelve partitions. The `clients' table is defined as shown
here:

     CREATE TABLE clients (
         id INT,
         fname VARCHAR(30),
         lname VARCHAR(30),
         signed DATE
     )
     PARTITION BY HASH( MONTH(signed) )
     PARTITIONS 12;

To reduce the number of partitions from twelve to eight, execute the
following *Note `ALTER TABLE': alter-table.  command:

     mysql> ALTER TABLE clients COALESCE PARTITION 4;
     Query OK, 0 rows affected (0.02 sec)

`COALESCE' works equally well with tables that are partitioned by
`HASH', `KEY', `LINEAR HASH', or `LINEAR KEY'. Here is an example
similar to the previous one, differing only in that the table is
partitioned by `LINEAR KEY':

     mysql> CREATE TABLE clients_lk (
         ->     id INT,
         ->     fname VARCHAR(30),
         ->     lname VARCHAR(30),
         ->     signed DATE
         -> )
         -> PARTITION BY LINEAR KEY(signed)
         -> PARTITIONS 12;
     Query OK, 0 rows affected (0.03 sec)

     mysql> ALTER TABLE clients_lk COALESCE PARTITION 4;
     Query OK, 0 rows affected (0.06 sec)
     Records: 0  Duplicates: 0  Warnings: 0

Note that the number following `COALESCE PARTITION' is the number of
partitions to merge into the remainder -- in other words, it is the
number of partitions to remove from the table.

If you attempt to remove more partitions than the table has, the result
is an error like the one shown:

     mysql> ALTER TABLE clients COALESCE PARTITION 18;
     ERROR 1478 (HY000): Cannot remove all partitions, use DROP TABLE instead

To increase the number of partitions for the `clients' table from 12 to
18. use `ALTER TABLE ... ADD PARTITION' as shown here:

     ALTER TABLE clients ADD PARTITION PARTITIONS 6;


File: manual.info,  Node: partitioning-maintenance,  Next: partitioning-info,  Prev: partitioning-management-hash-key,  Up: partitioning-management

17.3.3 Maintenance of Partitions
--------------------------------

A number of table and partition maintenance tasks can be carried out
using SQL statements intended for such purposes on partitioned tables
in MySQL 6.0.

Table maintenance of partitioned tables can be accomplished using the
statements *Note `CHECK TABLE': check-table, *Note `OPTIMIZE TABLE':
optimize-table, *Note `ANALYZE TABLE': analyze-table, and *Note `REPAIR
TABLE': repair-table, which are supported for partitioned tables as of
MySQL 6.0.6.

Also beginning with MySQL 6.0.6, you can use a number of extensions to
*Note `ALTER TABLE': alter-table. for performing operations of this
type on one or more partitions directly, as described in the following
list:

   * Rebuilding partitions

     Rebuilds the partition; this has the same effect as dropping all
     records stored in the partition, then reinserting them. This can
     be useful for purposes of defragmentation.

     Example:

          ALTER TABLE t1 REBUILD PARTITION p0, p1;

   * Optimizing partitions

     If you have deleted a large number of rows from a partition or if
     you have made many changes to a partitioned table with
     variable-length rows (that is, having `VARCHAR', `BLOB', or `TEXT'
     columns), you can use `ALTER TABLE ... OPTIMIZE PARTITION' to
     reclaim any unused space and to defragment the partition data file.

     Example:

          ALTER TABLE t1 OPTIMIZE PARTITION p0, p1;

     Using `OPTIMIZE PARTITION' on a given partition is equivalent to
     running `CHECK PARTITION', `ANALYZE PARTITION', and `REPAIR
     PARTITION' on that partition.

   * Analyzing partitions

     This reads and stores the key distributions for partitions.

     Example:

          ALTER TABLE t1 ANALYZE PARTITION p3;

   * Repairing partitions

     This repairs corrupted partitions.

     Example:

          ALTER TABLE t1 REPAIR PARTITION p0,p1;

   * Checking partitions

     You can check partitions for errors in much the same way that you
     can use `CHECK TABLE' with non-partitioned tables.

     Example:

          ALTER TABLE trb3 CHECK PARTITION p1;

     This command will tell you if the data or indexes in partition
     `p1' of table `t1' are corrupted. If this is the case, use `ALTER
     TABLE ... REPAIR PARTITION' to repair the partition.

*Note*:

The statements `ALTER TABLE ... ANALYZE PARTITION', `ALTER TABLE ...
CHECK PARTITION', `ALTER TABLE ... OPTIMIZE PARTITION', and `ALTER
TABLE ... REPAIR PARTITION' did not work properly as originally
implemented, and were disabled in MySQL 6.0.5. They were re-introduced
in MySQL 6.0.6. (Bug#20129 (http://bugs.mysql.com/20129)) The use of
these partitioning-specific `ALTER TABLE' statements with tables which
are not partitioned is not supported; beginning with MySQL 6.0.8, it is
expressly disallowed. (Bug#39434 (http://bugs.mysql.com/39434))


File: manual.info,  Node: partitioning-info,  Prev: partitioning-maintenance,  Up: partitioning-management

17.3.4 Obtaining Information About Partitions
---------------------------------------------

This section discusses obtaining information about existing partitions,
which can be done in a number of ways. These include:

   * Using the *Note `SHOW CREATE TABLE': show-create-table.  statement
     to view the partitioning clauses used in creating a partitioned
     table.

   * Using the *Note `SHOW TABLE STATUS': show-table-status.  statement
     to determine whether a table is partitioned.

   * Querying the *Note `INFORMATION_SCHEMA.PARTITIONS':
     partitions-table.  table.

   * Using the statement `EXPLAIN PARTITIONS SELECT' to see which
     partitions are used by a given *Note `SELECT': select.

As discussed elsewhere in this chapter, *Note `SHOW CREATE TABLE':
show-create-table. includes in its output the `PARTITION BY' clause
used to create a partitioned table. For example:

     mysql> SHOW CREATE TABLE trb3\G
     *************************** 1. row ***************************
            Table: trb3
     Create Table: CREATE TABLE `trb3` (
       `id` int(11) default NULL,
       `name` varchar(50) default NULL,
       `purchased` date default NULL
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1
     PARTITION BY RANGE (YEAR(purchased)) (
       PARTITION p0 VALUES LESS THAN (1990) ENGINE = MyISAM,
       PARTITION p1 VALUES LESS THAN (1995) ENGINE = MyISAM,
       PARTITION p2 VALUES LESS THAN (2000) ENGINE = MyISAM,
       PARTITION p3 VALUES LESS THAN (2005) ENGINE = MyISAM
     )
     1 row in set (0.00 sec)

The output from *Note `SHOW TABLE STATUS': show-table-status.  for
partitioned tables is the same as that for non-partitioned tables,
except that the `Create_options' column contains the string
`partitioned'. The `Engine' column contains the name of the storage
engine used by all partitions of the table. (See *Note
show-table-status::, for more information about this statement.)

You can also obtain information about partitions from
`INFORMATION_SCHEMA', which contains a *Note `PARTITIONS':
partitions-table. table. See *Note partitions-table::.

It is possible to determine which partitions of a partitioned table are
involved in a given *Note `SELECT': select. query using `EXPLAIN
PARTITIONS'. The `PARTITIONS' keyword adds a `partitions' column to the
output of *Note `EXPLAIN': explain. listing the partitions from which
records would be matched by the query.

Suppose that you have a table `trb1' defined and populated as follows:

     CREATE TABLE trb1 (id INT, name VARCHAR(50), purchased DATE)
         PARTITION BY RANGE(id)
         (
             PARTITION p0 VALUES LESS THAN (3),
             PARTITION p1 VALUES LESS THAN (7),
             PARTITION p2 VALUES LESS THAN (9),
             PARTITION p3 VALUES LESS THAN (11)
         );

     INSERT INTO trb1 VALUES
         (1, 'desk organiser', '2003-10-15'),
         (2, 'CD player', '1993-11-05'),
         (3, 'TV set', '1996-03-10'),
         (4, 'bookcase', '1982-01-10'),
         (5, 'exercise bike', '2004-05-09'),
         (6, 'sofa', '1987-06-05'),
         (7, 'popcorn maker', '2001-11-22'),
         (8, 'aquarium', '1992-08-04'),
         (9, 'study desk', '1984-09-16'),
         (10, 'lava lamp', '1998-12-25');

You can see which partitions are used in a query such as `SELECT * FROM
trb1;', as shown here:

     mysql> EXPLAIN PARTITIONS SELECT * FROM trb1\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: trb1
        partitions: p0,p1,p2,p3
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: 10
             Extra: Using filesort

In this case, all four partitions are searched. However, when a
limiting condition making use of the partitioning key is added to the
query, you can see that only those partitions containing matching
values are scanned, as shown here:

     mysql> EXPLAIN PARTITIONS SELECT * FROM trb1 WHERE id < 5\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: trb1
        partitions: p0,p1
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: 10
             Extra: Using where

`EXPLAIN PARTITIONS' provides information about keys used and possible
keys, just as with the standard *Note `EXPLAIN SELECT': explain.
statement:

     mysql> ALTER TABLE trb1 ADD PRIMARY KEY (id);
     Query OK, 10 rows affected (0.03 sec)
     Records: 10  Duplicates: 0  Warnings: 0

     mysql> EXPLAIN PARTITIONS SELECT * FROM trb1 WHERE id < 5\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: trb1
        partitions: p0,p1
              type: range
     possible_keys: PRIMARY
               key: PRIMARY
           key_len: 4
               ref: NULL
              rows: 7
             Extra: Using where

You should take note of the following restrictions and limitations on
`EXPLAIN PARTITIONS':

   * You cannot use the `PARTITIONS' and `EXTENDED' keywords together
     in the same `EXPLAIN ... SELECT' statement. Attempting to do so
     produces a syntax error.

   * If `EXPLAIN PARTITIONS' is used to examine a query against a
     non-partitioned table, no error is produced, but the value of the
     `partitions' column is always `NULL'.

As of MySQL 6.0.7, the `rows' column of `EXPLAIN PARTITIONS' output
always displays the total number of records in the table. Previously,
this was the number of matching rows. (Bug#35745
(http://bugs.mysql.com/35745))

See also *Note explain::.


File: manual.info,  Node: partitioning-pruning,  Next: partitioning-limitations,  Prev: partitioning-management,  Up: partitioning

17.4 Partition Pruning
======================

This section discusses an optimization known as _partition pruning_.
The core concept behind partition pruning is relatively simple, and can
be described as `Do not scan partitions where there can be no matching
values'. For example, suppose you have a partitioned table `t1' defined
by this statement:

     CREATE TABLE t1 (
         fname VARCHAR(50) NOT NULL,
         lname VARCHAR(50) NOT NULL,
         region_code TINYINT UNSIGNED NOT NULL,
         dob DATE NOT NULL
     )
     PARTITION BY RANGE( region_code ) (
         PARTITION p0 VALUES LESS THAN (64),
         PARTITION p1 VALUES LESS THAN (128),
         PARTITION p2 VALUES LESS THAN (192),
         PARTITION p3 VALUES LESS THAN MAXVALUE
     );

Consider the case where you wish to obtain results from a query such as
this one:

     SELECT fname, lname, region_code, dob
         FROM t1
         WHERE region_code > 125 AND region_code < 130;

It is easy to see that none of the rows which ought to be returned will
be in either of the partitions `p0' or `p3'; that is, we need to search
only in partitions `p1' and `p2' to find matching rows. By doing so, it
is possible to expend much more time and effort in finding matching
rows than it is to scan all partitions in the table. This `cutting
away' of unneeded partitions is known as _pruning_.  When the optimizer
can make use of partition pruning in performing a query, execution of
the query can be an order of magnitude faster than the same query
against a non-partitioned table containing the same column definitions
and data.

The query optimizer can perform pruning whenever a `WHERE' condition
can be reduced to either one of the following:

   * `PARTITION_COLUMN = CONSTANT'

   * `PARTITION_COLUMN IN (CONSTANT1, CONSTANT2, ..., CONSTANTN)'

In the first case, the optimizer simply evaluates the partitioning
expression for the value given, determines which partition contains
that value, and scans only this partition. In many cases, the equals
sign can be replaced with another arithmetic comparison, including `<',
`>', `<=', `>=', and `<>'. Some queries using `BETWEEN' in the `WHERE'
clause can also take advantage of partition pruning. See the examples
later in this section.

In the second case, the optimizer evaluates the partitioning expression
for each value in the list, creates a list of matching partitions, and
then scans only the partitions in this partition list.

Pruning can also be applied to short ranges, which the optimizer can
convert into equivalent lists of values. For instance, in the previous
example, the `WHERE' clause can be converted to `WHERE region_code IN
(125, 126, 127, 128, 129, 130)'. Then the optimizer can determine that
the first three values in the list are found in partition `p1', the
remaining three values in partition `p2', and that the other partitions
contain no relevant values and so do not need to be searched for
matching rows.

This type of optimization can be applied whenever the partitioning
expression consists of an equality or a range which can be reduced to a
set of equalities, or when the partitioning expression represents an
increasing or decreasing relationship. Pruning can also be applied for
tables partitioned on a *Note `DATE': datetime. or *Note `DATETIME':
datetime. column when the partitioning expression uses the `YEAR()' or
`TO_DAYS()' function.

*Note*:

We plan to add pruning support in a future MySQL release for additional
functions that act on a *Note `DATE': datetime. or *Note `DATETIME':
datetime. value, return an integer, and are increasing or decreasing.

For example, suppose that table `t2', defined as shown here, is
partitioned on a *Note `DATE': datetime. column:

     CREATE TABLE t2 (
         fname VARCHAR(50) NOT NULL,
         lname VARCHAR(50) NOT NULL,
         region_code TINYINT UNSIGNED NOT NULL,
         dob DATE NOT NULL
     )
     PARTITION BY RANGE( YEAR(dob) ) (
         PARTITION d0 VALUES LESS THAN (1970),
         PARTITION d1 VALUES LESS THAN (1975),
         PARTITION d2 VALUES LESS THAN (1980),
         PARTITION d3 VALUES LESS THAN (1985),
         PARTITION d4 VALUES LESS THAN (1990),
         PARTITION d5 VALUES LESS THAN (2000),
         PARTITION d6 VALUES LESS THAN (2005),
         PARTITION d7 VALUES LESS THAN MAXVALUE
     );

The following queries on `t2' can make of use partition pruning:

     SELECT * FROM t2 WHERE dob = '1982-06-23';

     SELECT * FROM t2 WHERE dob BETWEEN '1991-02-15' AND '1997-04-25';

     SELECT * FROM t2 WHERE dob >= '1984-06-21' AND dob <= '1999-06-21'

In the case of the last query, the optimizer can also act as follows:

  1. _Find the partition containing the low end of the range_.

     `YEAR('1984-06-21')' yields the value `1984', which is found in
     partition `d3'.

  2. _Find the partition containing the high end of the range_.

     `YEAR('1999-06-21')' evaluates to `1999', which is found in
     partition `d5'.

  3. _Scan only these two partitions and any partitions that may lie
     between them_.

     In this case, this means that only partitions `d3', `d4', and `d5'
     are scanned. The remaining partitions may be safely ignored (and
     are ignored).

*Important*:

Invalid `DATE' and `DATETIME' values referenced in the `WHERE' clause
of a query on a partitioned table are treated as `NULL'. This means
that a query such as `SELECT * FROM PARTITIONED_TABLE WHERE DATE_COLUMN
< '2008-12-00'' does not return any values (see Bug#40972
(http://bugs.mysql.com/40972)).

So far, we have looked only at examples using `RANGE' partitioning, but
pruning can be applied with other partitioning types as well.

Consider a table that is partitioned by `LIST', where the partitioning
expression is increasing or decreasing, such as the table `t3' shown
here. (In this example, we assume for the sake of brevity that the
`region_code' column is limited to values between 1 and 10 inclusive.)

     CREATE TABLE t3 (
         fname VARCHAR(50) NOT NULL,
         lname VARCHAR(50) NOT NULL,
         region_code TINYINT UNSIGNED NOT NULL,
         dob DATE NOT NULL
     )
     PARTITION BY LIST(region_code) (
         PARTITION r0 VALUES IN (1, 3),
         PARTITION r1 VALUES IN (2, 5, 8),
         PARTITION r2 VALUES IN (4, 9),
         PARTITION r3 VALUES IN (6, 7, 10)
     );

For a query such as `SELECT * FROM t3 WHERE region_code BETWEEN 1 AND
3', the optimizer determines in which partitions the values 1, 2, and 3
are found (`r0' and `r1') and skips the remaining ones (`r2' and `r3').

For tables that are partitioned by `HASH' or `KEY', partition pruning
is also possible in cases in which the `WHERE' clause uses a simple `='
relation against a column used in the partitioning expression. Consider
a table created like this:

     CREATE TABLE t4 (
         fname VARCHAR(50) NOT NULL,
         lname VARCHAR(50) NOT NULL,
         region_code TINYINT UNSIGNED NOT NULL,
         dob DATE NOT NULL
     )
     PARTITION BY KEY(region_code)
     PARTITIONS 8;

Any query such as this one can be pruned:

     SELECT * FROM t4 WHERE region_code = 7;

Pruning can also be employed for short ranges, because the optimizer
can turn such conditions into `IN' relations. For example, using the
same table `t4' as defined previously, queries such as these can be
pruned:

     SELECT * FROM t4 WHERE region_code > 2 AND region_code < 6;

     SELECT * FROM t4 WHERE region_code BETWEEN 3 AND 5;

In both these cases, the `WHERE' clause is transformed by the optimizer
into `WHERE region_code IN (3, 4, 5)'.

*Important*:

This optimization is used only if the range size is smaller than the
number of partitions. Consider this query:

     SELECT * FROM t4 WHERE region_code BETWEEN 4 AND 8;

The range in the `WHERE' clause covers 5 values (4, 5, 6, 7, 8), but
`t4' has only 4 partitions. This means that the previous query cannot
be pruned.

Pruning can be used only on integer columns of tables partitioned by
`HASH' or `KEY'. For example, this query on table `t4' cannot use
pruning because `dob' is a *Note `DATE': datetime. column:

     SELECT * FROM t4 WHERE dob >= '2001-04-14' AND dob <= '2005-10-15';

However, if the table stores year values in an *Note `INT':
numeric-types. column, then a query having `WHERE year_col >= 2001 AND
year_col <= 2005' can be pruned.


File: manual.info,  Node: partitioning-limitations,  Prev: partitioning-pruning,  Up: partitioning

17.5 Restrictions and Limitations on Partitioning
=================================================

* Menu:

* partitioning-limitations-partitioning-keys-unique-keys::  Partitioning Keys, Primary Keys, and Unique Keys
* partitioning-limitations-storage-engines::  Partitioning Limitations Relating to Storage Engines
* partitioning-limitations-functions::  Partitioning Limitations Relating to Functions

This section discusses current restrictions and limitations on MySQL
partitioning support, as listed here:

   * Prohibited constructs

     The following constructs are not permitted in partitioning
     expressions:

        * Stored functions, stored procedures, UDFs, or plugins.

        * Declared variables or user variables.

     For a list of SQL functions which are permitted in partitioning
     expressions, see *Note partitioning-limitations-functions::.

   * Arithmetic and logical operators

     Use of the arithmetic operators `+', `-', and `*' is permitted in
     partitioning expressions. However, the result must be an integer
     value or `NULL' (except in the case of `[LINEAR] KEY' partitioning,
     as discussed elswhere in this chapter -- see *Note
     partitioning-types::, for more information).

     Beginning with MySQL 6.0.4, the `DIV' operator is also supported,
     and the `/' operator is disallowed. (Bug#30188
     (http://bugs.mysql.com/30188), Bug#33182
     (http://bugs.mysql.com/33182))

     The bit operators `|', `&', `^', `<<', `>>', and `~' are not
     permitted in partitioning expressions.

   * Server SQL mode

     Tables employing user-defined partitioning do not preserve the SQL
     mode in effect at the time that they were created.  As discussed
     in *Note server-sql-mode::, the results of many MySQL functions
     and operators may change according to the server SQL mode.
     Therefore, a change in the SQL mode at any time after the creation
     of partitioned tables may lead to major changes in the behavior of
     such tables, and could easily lead to corruption or loss of data.
     For these reasons, _it is strongly recommended that you never
     change the server SQL mode after creating partitioned tables_.

     Examples

     The following examples illustrate some changes in behavior of
     partitioned tables due to a change in the server SQL mode:

       1. Error handling

          Suppose you create a partitioned table whose partitioning
          expression is one such as `COLUMN DIV 0' or `COLUMN MOD 0',
          as shown here:

               mysql> CREATE TABLE tn (c1 INT)
                   ->     PARTITION BY LIST(1 DIV c1) (
                   ->       PARTITION p0 VALUES IN (NULL),
                   ->       PARTITION p1 VALUES IN (1)
                   -> );
               Query OK, 0 rows affected (0.05 sec)

          The default behavior for MySQL is to return `NULL' for the
          result of a division by zero, without producing any errors:

               mysql> SELECT @@SQL_MODE;
               +------------+
               | @@SQL_MODE |
               +------------+
               |            |
               +------------+
               1 row in set (0.00 sec)

               mysql> INSERT INTO tn VALUES (NULL), (0), (1);
               Query OK, 3 rows affected (0.00 sec)
               Records: 3  Duplicates: 0  Warnings: 0

          However, changing the server SQL mode to treat division by
          zero as an error and to enforce strict error handling causes
          the same *Note `INSERT': insert. statement to fail, as shown
          here:

               mysql> SET SQL_MODE='STRICT_ALL_TABLES,ERROR_FOR_DIVISION_BY_ZERO';
               Query OK, 0 rows affected (0.00 sec)

               mysql> INSERT INTO tn VALUES (NULL), (0), (1);
               `ERROR 1365 (22012): Division by 0'

       2. Table accessibility

          Sometimes a change in the server SQL mode can make
          partitioned tables unusable. The following *Note `CREATE
          TABLE': create-table.  statement can be executed successfully
          only if the `NO_UNSIGNED_SUBTRACTION' mode is in effect:

               mysql> SELECT @@SQL_MODE;
               +------------+
               | @@SQL_MODE |
               +------------+
               |            |
               +------------+
               1 row in set (0.00 sec)

               mysql> CREATE TABLE tu (c1 BIGINT UNSIGNED)
                   ->   PARTITION BY RANGE(c1 - 10) (
                   ->     PARTITION p0 VALUES LESS THAN (-5),
                   ->     PARTITION p1 VALUES LESS THAN (0),
                   ->     PARTITION p2 VALUES LESS THAN (5),
                   ->     PARTITION p3 VALUES LESS THAN (10),
                   ->     PARTITION p4 VALUES LESS THAN (MAXVALUE)
                   -> );
               `ERROR 1563 (HY000): Partition constant is out of partition function domain'

               mysql> SET SQL_MODE='NO_UNSIGNED_SUBTRACTION';
               Query OK, 0 rows affected (0.00 sec)

               mysql> SELECT @@SQL_MODE;
               +-------------------------+
               | @@SQL_MODE              |
               +-------------------------+
               | NO_UNSIGNED_SUBTRACTION |
               +-------------------------+
               1 row in set (0.00 sec)

               mysql> CREATE TABLE tu (c1 BIGINT UNSIGNED)
                   ->   PARTITION BY RANGE(c1 - 10) (
                   ->     PARTITION p0 VALUES LESS THAN (-5),
                   ->     PARTITION p1 VALUES LESS THAN (0),
                   ->     PARTITION p2 VALUES LESS THAN (5),
                   ->     PARTITION p3 VALUES LESS THAN (10),
                   ->     PARTITION p4 VALUES LESS THAN (MAXVALUE)
                   -> );
               Query OK, 0 rows affected (0.05 sec)

          If you remove the `NO_UNSIGNED_SUBTRACTION' server SQL mode
          after creating `tu', you may no longer be able to access this
          table:

               mysql> SET SQL_MODE='';
               Query OK, 0 rows affected (0.00 sec)

               mysql> SELECT * FROM tu;
               `ERROR 1563 (HY000): Partition constant is out of partition function domain'
               mysql> INSERT INTO tu VALUES (20);
               `ERROR 1563 (HY000): Partition constant is out of partition function domain'

   * Performance considerations

        * File system operations

          Partitioning and repartitioning operations (such as *Note
          `ALTER TABLE': alter-table. with `PARTITION BY ...',
          `REORGANIZE PARTITIONS', or `REMOVE PARTITIONING') depend on
          file system operations for their implementation.  This means
          that the speed of these operations is affected by such
          factors as file system type and characteristics, disk speed,
          swap space, file handling efficiency of the operating system,
          and MySQL server options and variables that relate to file
          handling. In particular, you should make sure that
          `large_files_support' is enabled and that `open_files_limit'
          is set properly. For partitioned tables using the `MyISAM'
          storage engine, increasing `myisam_max_sort_file_size' may
          improve performance; partitioning and repartitioning
          operations involving `InnoDB' tables may be made more
          efficient by enabling `innodb_file_per_table'.

        * Table locks

          The process executing a partitioning operation on a table
          takes a write lock on the table. Reads from such tables are
          relatively unaffected; pending *Note `INSERT': insert. and
          *Note `UPDATE': update. operations are performed as soon as
          the partitioning operation has completed.

        * Storage engine

          Partitioning operations, queries, and update operations
          generally tend to be faster with `MyISAM' tables than with
          `InnoDB' or `NDB' tables.

        * Use of indexes and partition pruning

          As with non-partitioned tables, proper use of indexes can
          speed up queries on partitioned tables significantly. In
          addition, designing partitioned tables and queries on these
          tables to take advantage of _partition pruning_ can improve
          performance dramatically. See *Note partitioning-pruning::,
          for more information.

        * Performance with `LOAD DATA'

          Prior to MySQL 6.0.4, *Note `LOAD DATA': load-data. performed
          very poorly when importing into partitioned tables. The
          statement now uses buffering to improve performance; however,
          the buffer uses 130 KB memory per partition to achieve this.
          (Bug#26527 (http://bugs.mysql.com/26527))

   * Maximum number of partitions

     The maximum number of partitions possible for a given table is
     1024. This includes subpartitions.

     If, when creating tables with a very large number of partitions
     (but which is less than the maximum stated previously), you
     encounter an error message such as `Got error 24 from storage
     engine', this means that you may need to increase the value of the
     `open_files_limit' system variable. See *Note
     not-enough-file-handles::.

   * Foreign keys not supported

     Partitioned tables do not support foreign keys. This means that:

       1. Definitions of tables employing user-defined partitioning may
          not contain foreign key references to other tables.

       2. No table definition may contain a foreign key reference to a
          partitioned table.

     The scope of these restrictions includes tables that use the
     `InnoDB' storage engine.

   * `ALTER TABLE ... ORDER BY'

     An `ALTER TABLE ... ORDER BY COLUMN' statement run against a
     partitioned table causes ordering of rows only within each
     partition.

   * FULLTEXT indexes

     Partitioned tables do not support `FULLTEXT' indexes. This includes
     partitioned tables employing the `MyISAM' storage engine.

   * Spatial columns

     Columns with spatial data types such as `POINT' or `GEOMETRY'
     cannot be used in partitioned tables.

   * Temporary tables

     Temporary tables cannot be partitioned. (Bug#17497
     (http://bugs.mysql.com/17497))

   * Log tables

     It is not possible to partition the log tables; an `ALTER TABLE
     ... PARTITION BY ...' statement on such a table fails with an
     error. (Bug#27816 (http://bugs.mysql.com/27816))

   * Data type of partitioning key

     A partitioning key must be either an integer column or an
     expression that resolves to an integer. The column or expression
     value may also be `NULL'. (See *Note
     partitioning-handling-nulls::.)

     The lone exception to this restriction occurs when partitioning by
     [`LINEAR'] `KEY', where it is possible to use columns of other
     types as partitioning keys, because MySQL's internal key-hashing
     functions produce the correct data type from these types. For
     example, the following *Note `CREATE TABLE': create-table.
     statement is valid:

          CREATE TABLE tkc (c1 CHAR)
          PARTITION BY KEY(c1)
          PARTITIONS 4;

     This exception does _not_ apply to *Note `BLOB': blob. or *Note
     `TEXT': blob. column types.

   * Subqueries

     A partitioning key may not be a subquery, even if that subquery
     resolves to an integer value or `NULL'.

   * Subpartitions

     Subpartitions are limited to `HASH' or `KEY' partitioning. `HASH'
     and `KEY' partitions cannot be subpartitioned.

   * Key caches not supported

     Key caches are not supported for partitioned tables. The *Note
     `CACHE INDEX': cache-index. and *Note `LOAD INDEX INTO CACHE':
     load-index. statements, when you attempt to use them on tables
     having user-defined partitioning, fail with the errors `The
     storage engine for the table doesn't support assign_to_keycache'
     and `The storage engine for the table doesn't support
     preload_keys', respectively.

   * `DELAYED' option not supported

     Use of *Note `INSERT DELAYED': insert-delayed. to insert rows into
     a partitioned table is not supported.  Beginning with MySQL 6.0.4,
     attempting to do so fails with an error. (Bug#31210
     (http://bugs.mysql.com/31210))

   * `DATA DIRECTORY' and `INDEX DIRECTORY' options

     `DATA DIRECTORY' and `INDEX DIRECTORY' are subject to the following
     restrictions when used with partitioned tables:

        * Beginning with MySQL 6.0.4, table-level `DATA DIRECTORY' and
          `INDEX DIRECTORY' options are ignored. (Bug#32091
          (http://bugs.mysql.com/32091))

        * On Windows, the `DATA DIRECTORY' and `INDEX DIRECTORY'
          options are not supported for individual partitions or
          subpartitions (Bug#30459 (http://bugs.mysql.com/30459)).

   * Repairing and rebuilding partitioned tables

     The statements *Note `CHECK TABLE': check-table, *Note `OPTIMIZE
     TABLE': optimize-table, *Note `ANALYZE TABLE': analyze-table, and
     *Note `REPAIR TABLE': repair-table. are supported for partitioned
     tables beginning with MySQL 6.0.6. (See Bug#20129
     (http://bugs.mysql.com/20129).) *Note `mysqlcheck': mysqlcheck. and
     *Note `myisamchk': myisamchk. are not supported with partitioned
     tables.

     In addition, you can use `ALTER TABLE ... REBUILD PARTITION' to
     rebuild one or more partitions of a partitioned table; `ALTER
     TABLE ... REORGANIZE PARTITION' also causes partitions to be
     rebuilt. See *Note alter-table::, for more information about these
     two statements.


File: manual.info,  Node: partitioning-limitations-partitioning-keys-unique-keys,  Next: partitioning-limitations-storage-engines,  Prev: partitioning-limitations,  Up: partitioning-limitations

17.5.1 Partitioning Keys, Primary Keys, and Unique Keys
-------------------------------------------------------

This section discusses the relationship of partitioning keys with
primary keys and unique keys. The rule governing this relationship can
be expressed as follows: All columns used in the partitioning
expression for a partitioned table must be part of every unique key
that the table may have.

In other words, _every unique key on the table must use every column in
the table's partitioning expression_.  (This also includes the table's
primary key, since it is by definition a unique key. This particular
case is discussed later in this section.) For example, each of the
following table creation statements is invalid:

     CREATE TABLE t1 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         UNIQUE KEY (col1, col2)
     )
     PARTITION BY HASH(col3)
     PARTITIONS 4;

     CREATE TABLE t2 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         UNIQUE KEY (col1),
         UNIQUE KEY (col3)
     )
     PARTITION BY HASH(col1 + col3)
     PARTITIONS 4;

In each case, the proposed table would have at least one unique key
that does not include all columns used in the partitioning expression.

Each of the following statements is valid, and represents one way in
which the corresponding invalid table creation statement could be made
to work:

     CREATE TABLE t1 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         UNIQUE KEY (col1, col2, col3)
     )
     PARTITION BY HASH(col3)
     PARTITIONS 4;

     CREATE TABLE t2 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         UNIQUE KEY (col1, col3)
     )
     PARTITION BY HASH(col1 + col3)
     PARTITIONS 4;

This example shows the error produced in such cases:

     mysql> CREATE TABLE t3 (
         ->     col1 INT NOT NULL,
         ->     col2 DATE NOT NULL,
         ->     col3 INT NOT NULL,
         ->     col4 INT NOT NULL,
         ->     UNIQUE KEY (col1, col2),
         ->     UNIQUE KEY (col3)
         -> )
         -> PARTITION BY HASH(col1 + col3)
         -> PARTITIONS 4;
     `ERROR 1491 (HY000): A PRIMARY KEY must include all columns in the table's partitioning function'

The `CREATE' statement fails because both `col1' and `col3' are included
in the proposed partitioning key, but neither of these columns is part
of both of unique keys on the table. This shows one possible fix for
the invalid table definition;

     mysql> CREATE TABLE t3 (
         ->     col1 INT NOT NULL,
         ->     col2 DATE NOT NULL,
         ->     col3 INT NOT NULL,
         ->     col4 INT NOT NULL,
         ->     UNIQUE KEY (col1, col2, col3),
         ->     UNIQUE KEY (col3)
         -> )
         -> PARTITION BY HASH(col3)
         -> PARTITIONS 4;
     Query OK, 0 rows affected (0.05 sec)

In this case, the proposed partitioning key `col3' is part of both
unique keys, and the table creation statement succeeds.

Since every primary key is by definition a unique key, this restriction
also includes the table's primary key, if it has one. For example, the
next two statements are invalid:

     CREATE TABLE t4 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         PRIMARY KEY(col1, col2)
     )
     PARTITION BY HASH(col3)
     PARTITIONS 4;

     CREATE TABLE t5 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         PRIMARY KEY(col1, col3),
         UNIQUE KEY(col2)
     )
     PARTITION BY HASH( YEAR(col2) )
     PARTITIONS 4;

In both cases, the primary key does not include all columns referenced
in the partitioning expression. However, both of the next two
statements are valid:

     CREATE TABLE t6 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         PRIMARY KEY(col1, col2)
     )
     PARTITION BY HASH(col1 + YEAR(col2))
     PARTITIONS 4;

     CREATE TABLE t7 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         PRIMARY KEY(col1, col2, col4),
         UNIQUE KEY(col2, col1)
     )
     PARTITION BY HASH(col1 + YEAR(col2))
     PARTITIONS 4;

If a table has no unique keys -- this includes having no primary key --
then this restriction does not apply, and you may use any column or
columns in the partitioning expression as long as the column type is
compatible with the partitioning type.

For the same reason, you cannot later add a unique key to a partitioned
table unless the key includes all columns used by the table's
partitioning expression. Consider given the partitioned table defined
as shown here:

     mysql> CREATE TABLE t_no_pk (c1 INT, c2 INT)
         ->     PARTITION BY RANGE(c1) (
         ->         PARTITION p0 VALUES LESS THAN (10),
         ->         PARTITION p1 VALUES LESS THAN (20),
         ->         PARTITION p2 VALUES LESS THAN (30),
         ->         PARTITION p3 VALUES LESS THAN (40)
         ->     );
     Query OK, 0 rows affected (0.12 sec)

It is possible to add a primary key to `t_no_pk' using either of these
*Note `ALTER TABLE': alter-table. statements:

     #  possible PK
     mysql> ALTER TABLE t_no_pk ADD PRIMARY KEY(c1);
     Query OK, 0 rows affected (0.13 sec)
     Records: 0  Duplicates: 0  Warnings: 0

     # drop this PK
     mysql> ALTER TABLE t_no_pk DROP PRIMARY KEY;
     Query OK, 0 rows affected (0.10 sec)
     Records: 0  Duplicates: 0  Warnings: 0

     #  use another possible PK
     mysql> ALTER TABLE t_no_pk ADD PRIMARY KEY(c1, c2);
     Query OK, 0 rows affected (0.12 sec)
     Records: 0  Duplicates: 0  Warnings: 0

     # drop this PK
     mysql> ALTER TABLE t_no_pk DROP PRIMARY KEY;
     Query OK, 0 rows affected (0.09 sec)
     Records: 0  Duplicates: 0  Warnings: 0

However, the next statement fails, because `c1' is part of the
partitioning key, but is not part of the proposed primary key:

     #  fails with error 1503
     mysql> ALTER TABLE t_no_pk ADD PRIMARY KEY(c2);
     `ERROR 1503 (HY000): A PRIMARY KEY must include all columns in the table's partitioning function'

Since `t_no_pk' has only `c1' in its partitioning expression,
attempting to adding a unique key on `c2' alone fails. However, you can
add a unique key that uses both `c1' and `c2'.

These rules also apply to existing non-partitioned tables that you wish
to partition using `ALTER TABLE ... PARTITION BY'. Consider a table
`np_pk' defined as shown here:

     mysql> CREATE TABLE np_pk (
         ->     id INT NOT NULL AUTO_INCREMENT,
         ->     name VARCHAR(50),
         ->     added DATE,
         ->     PRIMARY KEY (id)
         -> );
     Query OK, 0 rows affected (0.08 sec)

The following *Note `ALTER TABLE': alter-table.  statements fails with
an error, because the `added' column is not part of any unique key in
the table:

     mysql> ALTER TABLE np_pk
         ->     PARTITION BY HASH( TO_DAYS(added) )
         ->     PARTITIONS 4;
     `ERROR 1503 (HY000): A PRIMARY KEY must include all columns in the table's partitioning function'

However, this statement using the `id' column for the partitioning
column is valid, as shown here:

     mysql> ALTER TABLE np_pk
         ->     PARTITION BY HASH(id)
         ->     PARTITIONS 4;
     Query OK, 0 rows affected (0.11 sec)
     Records: 0  Duplicates: 0  Warnings: 0

In the case of `np_pk', the only column that may be used as part of a
partitioning expression is `id'; if you wish to partition this table
using any other column or columns in the partitioning expression, you
must first modify the table, either by adding the desired column or
columns to the primary key, or by dropping the primary key altogether.

We are working to remove this limitation in a future MySQL release
series.


File: manual.info,  Node: partitioning-limitations-storage-engines,  Next: partitioning-limitations-functions,  Prev: partitioning-limitations-partitioning-keys-unique-keys,  Up: partitioning-limitations

17.5.2 Partitioning Limitations Relating to Storage Engines
-----------------------------------------------------------

The following limitations apply to the use of storage engines with
user-defined partitioning of tables.

`MERGE' storage engine

User-defined partitioning and the `MERGE' storage engine are not
compatible. Tables using the `MERGE' storage engine cannot be
partitioned.  Partitioned tables cannot be merged.

`FEDERATED' storage engine

Partitioning of `FEDERATED' tables is not supported; it is not possible
to create partitioned `FEDERATED' tables. We are working to remove this
limitation in a future MySQL release.

`CSV' storage engine

Partitioned tables using the `CSV' storage engine are not supported; it
is not possible to create partitioned `CSV' tables.

Upgrading partitioned tables

When performing an upgrade, tables which are partitioned by `KEY' must
be dumped and reloaded.

Same storage engine for all partitions

All partitions of a partitioned table must use the same storage engine
and it must be the same storage engine used by the table as a whole. In
addition, if one does not specify an engine on the table level, then
one must do either of the following when creating or altering a
partitioned table:

   * Do _not_ specify any engine for _any_ partition or subpartition

   * Specify the engine for _all_ partitions or subpartitions

We are working to remove this limitation in a future MySQL release.


File: manual.info,  Node: partitioning-limitations-functions,  Prev: partitioning-limitations-storage-engines,  Up: partitioning-limitations

17.5.3 Partitioning Limitations Relating to Functions
-----------------------------------------------------

This section discusses limitations in MySQL Partitioning relating
specifically to functions used in partitioning expressions.

Only the following MySQL functions are supported in partitioning
expressions:

   * `ABS()'

   * `CEILING()' (see ``CEILING()' and `FLOOR()'', immediately
     following this list)

   * `DAY()'

   * `DAYOFMONTH()'

   * `DAYOFWEEK()'

   * `DAYOFYEAR()'

   * `DATEDIFF()'

   * `EXTRACT()'

   * `FLOOR()' (see ``CEILING()' and `FLOOR()'', immediately following
     this list)

   * `HOUR()'

   * `MICROSECOND()'

   * `MINUTE()'

   * `MOD()'

   * `MONTH()'

   * `QUARTER()'

   * `SECOND()'

   * `TIME_TO_SEC()'

   * `TO_DAYS()'

   * `WEEKDAY()'

   * `YEAR()'

   * `YEARWEEK()'

*Note*:

`CEILING()' and `FLOOR()'

Each of these functions returns an integer only if it is passed an
integer argument. This means, for example, that the following *Note
`CREATE TABLE': create-table.  statement fails with an error, as shown
here:

     mysql> CREATE TABLE t (c FLOAT) PARTITION BY LIST( FLOOR(c) )(
         ->     PARTITION p0 VALUES IN (1,3,5),
         ->     PARTITION p1 VALUES IN (2,4,6)
         -> );
     `ERROR 1490 (HY000): The PARTITION function returns the wrong type'

See *Note mathematical-functions::, for more information about the
return types of these functions.


File: manual.info,  Node: stored-programs-views,  Next: information-schema,  Prev: partitioning,  Up: Top

18 Stored Programs and Views
****************************

* Menu:

* stored-programs-defining::     Defining Stored Programs
* stored-routines::              Using Stored Routines (Procedures and Functions)
* triggers::                     Using Triggers
* events::                       Using the Event Scheduler
* views::                        Using Views
* stored-programs-logging::      Binary Logging of Stored Programs

This chapter discusses stored programs and views, which are database
objects defined in terms of SQL code that is stored on the server for
later invocation.

Stored programs include these objects:

   * Stored routines, that is, stored procedures and functions. A
     stored function is used much like a built-in function. you invoke
     it in an expression and it returns a value during expression
     evaluation. A stored procedure is invoked using the *Note `CALL':
     call. statement. A procedure does not have a return value but can
     modify its parameters for later inspection by the caller. It can
     also generate result sets to be returned to the client program.

   * Triggers. A trigger is a named database object that is associated
     with a table and that is activated when a particular event occurs
     for the table, such as an insert or update.

   * Events. An event is a task that runs according to schedule.

Views are stored queries that when invoked produce a result set. A view
acts as a virtual table.

This chapter describes how to use each type of stored program and views.

Additional information about SQL syntax for statements related to these
objects is available in the following locations:

   * For each object type, there are `CREATE', `ALTER', and `DROP'
     statements that control which objects exist and how they are
     defined. See *Note sql-syntax-data-definition::.

   * The *Note `CALL': call. statement is used to invoke stored
     procedures. See *Note call::.

   * Stored program definitions contain a body that may use compound
     statements, loops, conditionals, and declared variables. See *Note
     sql-syntax-compound-statements::.


File: manual.info,  Node: stored-programs-defining,  Next: stored-routines,  Prev: stored-programs-views,  Up: stored-programs-views

18.1 Defining Stored Programs
=============================

Each stored program contains a body that consists of an SQL statement.
This statement may be a compound statement made up of several
statements separated by semicolon (`;') characters. For example, the
following stored procedure has a body made up of a `BEGIN ... END'
block that contains a *Note `SET': set-option.  statement and a *Note
`REPEAT': repeat-statement.  loop that itself contains another *Note
`SET': set-option.  statement:

     CREATE PROCEDURE dorepeat(p1 INT)
     BEGIN
       SET @x = 0;
       REPEAT SET @x = @x + 1; UNTIL @x > p1 END REPEAT;
     END

If you use the *Note `mysql': mysql. client program to define a stored
program that contains the semicolon characters within its definition, a
problem arises. By default, *Note `mysql': mysql.  itself recognizes
semicolon as a statement delimiter, so you must redefine the delimiter
temporarily to cause *Note `mysql': mysql. to pass the entire stored
program definition to the server.

To redefine the *Note `mysql': mysql. delimiter, use the `delimiter'
command. The following example shows how to do this for the
`dorepeat()' procedure just shown. The delimiter is changed to `//' to
enable the entire definition to be passed to the server as a single
statement, and then restored to `;' before invoking the procedure. This
allows the `;' delimiter used in the procedure body to be passed
through to the server rather than being interpreted by *Note `mysql':
mysql.  itself.

     mysql> delimiter //

     mysql> CREATE PROCEDURE dorepeat(p1 INT)
         -> BEGIN
         ->   SET @x = 0;
         ->   REPEAT SET @x = @x + 1; UNTIL @x > p1 END REPEAT;
         -> END
         -> //
     Query OK, 0 rows affected (0.00 sec)

     mysql> delimiter ;

     mysql> CALL dorepeat(1000);
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @x;
     +------+
     | @x   |
     +------+
     | 1001 |
     +------+
     1 row in set (0.00 sec)

You can redefine the delimiter to a string other than `//', and the
delimiter can consist of a single character or multiple characters. You
should avoid the use of the backslash (``\'') character because that is
the escape character for MySQL.

The following is an example of a function that takes a parameter,
performs an operation using an SQL function, and returns the result. In
this case, it is unnecessary to use `delimiter' because the function
definition contains no internal `;' statement delimiters:

     mysql> CREATE FUNCTION hello (s CHAR(20))
     mysql> RETURNS CHAR(50) DETERMINISTIC
         -> RETURN CONCAT('Hello, ',s,'!');
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT hello('world');
     +----------------+
     | hello('world') |
     +----------------+
     | Hello, world!  |
     +----------------+
     1 row in set (0.00 sec)


File: manual.info,  Node: stored-routines,  Next: triggers,  Prev: stored-programs-defining,  Up: stored-programs-views

18.2 Using Stored Routines (Procedures and Functions)
=====================================================

* Menu:

* stored-routines-syntax::       Stored Routine Syntax
* stored-routines-privileges::   Stored Routines and MySQL Privileges
* stored-routines-metadata::     Stored Routine Metadata
* stored-routines-last-insert-id::  Stored Procedures, Functions, Triggers, and `LAST_INSERT_ID()'

Stored routines (procedures and functions) are supported in MySQL 6.0.
A stored routine is a set of SQL statements that can be stored in the
server. Once this has been done, clients don't need to keep reissuing
the individual statements but can refer to the stored routine instead.

Stored routines require the `proc' table in the `mysql' database. This
table is created during the MySQL 6.0 installation procedure. If you
are upgrading to MySQL 6.0 from an earlier version, be sure to update
your grant tables to make sure that the `proc' table exists. See *Note
mysql-upgrade::.

MySQL Enterprise

For expert advice on using stored procedures and functions subscribe to
the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

Stored routines can be particularly useful in certain situations:

   * When multiple client applications are written in different
     languages or work on different platforms, but need to perform the
     same database operations.

   * When security is paramount. Banks, for example, use stored
     procedures and functions for all common operations. This provides
     a consistent and secure environment, and routines can ensure that
     each operation is properly logged. In such a setup, applications
     and users would have no access to the database tables directly,
     but can only execute specific stored routines.

Stored routines can provide improved performance because less
information needs to be sent between the server and the client. The
tradeoff is that this does increase the load on the database server
because more of the work is done on the server side and less is done on
the client (application) side. Consider this if many client machines
(such as Web servers) are serviced by only one or a few database
servers.

Stored routines also allow you to have libraries of functions in the
database server. This is a feature shared by modern application
languages that allow such design internally (for example, by using
classes). Using these client application language features is
beneficial for the programmer even outside the scope of database use.

MySQL follows the SQL:2003 syntax for stored routines, which is also
used by IBM's DB2.

The MySQL implementation of stored routines is still in progress.  All
syntax described here is supported and any limitations and extensions
are documented where appropriate.

*Additional resources*

   * You may find the Stored Procedures User Forum
     (http://forums.mysql.com/list.php?98) of use when working with
     stored procedures and functions.

   * For answers to some commonly asked questions regarding stored
     routines in MySQL, see *Note faqs-stored-procs::.

   * There are some restrictions on the use of stored routines. See
     *Note stored-program-restrictions::.

   * Binary logging for stored routines takes place as described in
     *Note stored-programs-logging::.


File: manual.info,  Node: stored-routines-syntax,  Next: stored-routines-privileges,  Prev: stored-routines,  Up: stored-routines

18.2.1 Stored Routine Syntax
----------------------------

A stored routine is either a procedure or a function. Stored routines
are created with the *Note `CREATE PROCEDURE': create-procedure. and
*Note `CREATE FUNCTION': create-function. statements (see *Note
create-procedure::). A procedure is invoked using a *Note `CALL': call.
statement (see *Note call::), and can only pass back values using
output variables. A function can be called from inside a statement just
like any other function (that is, by invoking the function's name), and
can return a scalar value. The body of a stored routine can use
compound statements (see *Note sql-syntax-compound-statements::).

Stored routines can be dropped with the *Note `DROP PROCEDURE':
drop-procedure. and *Note `DROP FUNCTION': drop-function. statements
(see *Note drop-procedure::), and altered with the *Note `ALTER
PROCEDURE': alter-procedure. and *Note `ALTER FUNCTION':
alter-function. statements (see *Note alter-procedure::).

A stored procedure or function is associated with a particular
database. This has several implications:

   * When the routine is invoked, an implicit `USE DB_NAME' is
     performed (and undone when the routine terminates).  *Note `USE':
     use. statements within stored routines are disallowed.

   * You can qualify routine names with the database name. This can be
     used to refer to a routine that is not in the current database.
     For example, to invoke a stored procedure `p' or function `f' that
     is associated with the `test' database, you can say `CALL
     test.p()' or `test.f()'.

   * When a database is dropped, all stored routines associated with it
     are dropped as well.

Stored functions cannot be recursive.

Recursion in stored procedures is allowed but disabled by default.  To
enable recursion, set the `max_sp_recursion_depth' server system
variable to a value greater than zero. Stored procedure recursion
increases the demand on thread stack space. If you increase the value of
`max_sp_recursion_depth', it may be necessary to increase thread stack
size by increasing the value of `thread_stack' at server startup.  See
*Note server-system-variables::, for more information.

MySQL supports the very useful extension that allows the use of regular
*Note `SELECT': select. statements (that is, without using cursors or
local variables) inside a stored procedure. The result set of such a
query is simply sent directly to the client. Multiple *Note `SELECT':
select.  statements generate multiple result sets, so the client must
use a MySQL client library that supports multiple result sets. This
means the client must use a client library from a version of MySQL at
least as recent as 4.1. The client should also specify the
`CLIENT_MULTI_RESULTS' option when it connects.  For C programs, this
can be done with the *Note `mysql_real_connect()': mysql-real-connect.
C API function. See *Note mysql-real-connect::, and *Note
c-api-multiple-queries::.

MySQL Enterprise

MySQL Enterprise subscribers will find numerous articles about stored
routines in the MySQL Enterprise Knowledge Base. Access to this
collection of articles is one of the advantages of subscribing to MySQL
Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: stored-routines-privileges,  Next: stored-routines-metadata,  Prev: stored-routines-syntax,  Up: stored-routines

18.2.2 Stored Routines and MySQL Privileges
-------------------------------------------

The MySQL grant system takes stored routines into account as follows:

   * The `CREATE ROUTINE' privilege is needed to create stored routines.

   * The `ALTER ROUTINE' privilege is needed to alter or drop stored
     routines. This privilege is granted automatically to the creator
     of a routine if necessary, and dropped when the routine creator
     drops the routine.

   * The `EXECUTE' privilege is required to execute stored routines.
     However, this privilege is granted automatically to the creator of
     a routine if necessary (and dropped when the creator drops the
     routine).  Also, the default `SQL SECURITY' characteristic for a
     routine is `DEFINER', which enables users who have access to the
     database with which the routine is associated to execute the
     routine.

   * If the `automatic_sp_privileges' system variable is 0, the
     `EXECUTE' and `ALTER ROUTINE' privileges are not automatically
     granted and dropped.

The server manipulates the `mysql.proc' table in response to statements
that create, alter, or drop stored routines. It is not supported that
the server will notice manual manipulation of this table.


File: manual.info,  Node: stored-routines-metadata,  Next: stored-routines-last-insert-id,  Prev: stored-routines-privileges,  Up: stored-routines

18.2.3 Stored Routine Metadata
------------------------------

Metadata about stored routines can be obtained as follows:

   * Query the *Note `ROUTINES': routines-table. and *Note
     `PARAMETERS': parameters-table. tables of the `INFORMATION_SCHEMA'
     database. See *Note routines-table::, and *Note parameters-table::.

   * Use the *Note `SHOW CREATE PROCEDURE': show-create-procedure.  and
     *Note `SHOW CREATE FUNCTION': show-create-function.  statements to
     see routine definitions. See *Note show-create-procedure::.

   * Use the *Note `SHOW PROCEDURE STATUS': show-procedure-status.  and
     *Note `SHOW FUNCTION STATUS': show-function-status.  statements to
     see routine characteristics. See *Note show-procedure-status::.


File: manual.info,  Node: stored-routines-last-insert-id,  Prev: stored-routines-metadata,  Up: stored-routines

18.2.4 Stored Procedures, Functions, Triggers, and `LAST_INSERT_ID()'
---------------------------------------------------------------------

Within the body of a stored routine (procedure or function) or a
trigger, the value of `LAST_INSERT_ID()' changes the same way as for
statements executed outside the body of these kinds of objects (see
*Note information-functions::). The effect of a stored routine or
trigger upon the value of `LAST_INSERT_ID()' that is seen by following
statements depends on the kind of routine:

   * If a stored procedure executes statements that change the value of
     `LAST_INSERT_ID()', the changed value is seen by statements that
     follow the procedure call.

   * For stored functions and triggers that change the value, the value
     is restored when the function or trigger ends, so following
     statements do not see a changed value.


File: manual.info,  Node: triggers,  Next: events,  Prev: stored-routines,  Up: stored-programs-views

18.3 Using Triggers
===================

* Menu:

* trigger-syntax::               Trigger Syntax
* trigger-metadata::             Trigger Metadata

A trigger is a named database object that is associated with a table,
and that activates when a particular event occurs for the table. Some
uses for triggers are to perform checks of values to be inserted into a
table or to perform calculations on values involved in an update.

A trigger is defined to activate when an *Note `INSERT': insert, *Note
`DELETE': delete, or *Note `UPDATE': update. statement executes for the
associated table. A trigger can be set to activate either before or
after the triggering statement. For example, you can have a trigger
activate before each row that is inserted into a table or after each
row that is updated.

*Important*:

MySQL triggers are activated by SQL statements _only_. They are not
activated by changes in tables made by APIs that do not transmit SQL
statements to the MySQL Server; in particular, they are not activated
by updates made using the `NDB' API.

To use triggers if you have upgraded to MySQL 6.0 from an older release
that did not support triggers, you should upgrade your grant tables so
that they contain the trigger-related privileges. See *Note
mysql-upgrade::.

The following discussion describes the syntax for creating and dropping
triggers, and shows some examples of how to use them.

*Additional resources*

   * You may find the Triggers User Forum
     (http://forums.mysql.com/list.php?100) of use when working with
     views.

   * For answers to some commonly asked questions regarding triggers in
     MySQL, see *Note faqs-triggers::.

   * There are some restrictions on the use of triggers; see *Note
     stored-program-restrictions::.

   * Binary logging for triggers takes place as described in *Note
     stored-programs-logging::.


File: manual.info,  Node: trigger-syntax,  Next: trigger-metadata,  Prev: triggers,  Up: triggers

18.3.1 Trigger Syntax
---------------------

To create a trigger or drop a trigger, use the *Note `CREATE TRIGGER':
create-trigger. or *Note `DROP TRIGGER': drop-trigger. statement. The
syntax for these statements is described in *Note create-trigger::, and
*Note drop-trigger::.

Here is a simple example that associates a trigger with a table for
*Note `INSERT': insert. statements. The trigger acts as an accumulator,
summing the values inserted into one of the columns of the table.

     mysql> CREATE TABLE account (acct_num INT, amount DECIMAL(10,2));
     Query OK, 0 rows affected (0.03 sec)

     mysql> CREATE TRIGGER ins_sum BEFORE INSERT ON account
         -> FOR EACH ROW SET @sum = @sum + NEW.amount;
     Query OK, 0 rows affected (0.06 sec)

The *Note `CREATE TRIGGER': create-trigger. statement creates a trigger
named `ins_sum' that is associated with the `account' table. It also
includes clauses that specify the trigger activation time, the
triggering event, and what to do with the trigger activates:

   * The keyword `BEFORE' indicates the trigger action time. In this
     case, the trigger should activate before each row inserted into
     the table. The other allowable keyword here is `AFTER'.

   * The keyword *Note `INSERT': insert. indicates the event that
     activates the trigger. In the example, *Note `INSERT': insert.
     statements cause trigger activation. You can also create triggers
     for *Note `DELETE': delete. and *Note `UPDATE': update. statements.

   * The statement following `FOR EACH ROW' defines the statement to
     execute each time the trigger activates, which occurs once for
     each row affected by the triggering statement In the example, the
     triggered statement is a simple *Note `SET': set-option. that
     accumulates the values inserted into the `amount' column. The
     statement refers to the column as `NEW.amount' which means `the
     value of the `amount' column to be inserted into the new row.'

To use the trigger, set the accumulator variable to zero, execute an
*Note `INSERT': insert. statement, and then see what value the variable
has afterward:

     mysql> SET @sum = 0;
     mysql> INSERT INTO account VALUES(137,14.98),(141,1937.50),(97,-100.00);
     mysql> SELECT @sum AS 'Total amount inserted';
     +-----------------------+
     | Total amount inserted |
     +-----------------------+
     | 1852.48               |
     +-----------------------+

In this case, the value of `@sum' after the *Note `INSERT': insert.
statement has executed is `14.98 + 1937.50 - 100', or `1852.48'.

To destroy the trigger, use a *Note `DROP TRIGGER': drop-trigger.
statement. You must specify the schema name if the trigger is not in
the default schema:

     mysql> DROP TRIGGER test.ins_sum;

Triggers for a table are also dropped if you drop the table.

Trigger names exist in the schema namespace, meaning that all triggers
must have unique names within a schema. Triggers in different schemas
can have the same name.

In addition to the requirement that trigger names be unique for a
schema, there are other limitations on the types of triggers you can
create. In particular, you cannot have two triggers for a table that
have the same activation time and activation event. For example, you
cannot define two `BEFORE INSERT' triggers or two `AFTER UPDATE'
triggers for a table. This should rarely be a significant limitation,
because it is possible to define a trigger that executes multiple
statements by using the `BEGIN ... END' compound statement construct
after `FOR EACH ROW'. (An example appears later in this section.)

The `OLD' and `NEW' keywords enable you to access columns in the rows
affected by a trigger.  (`OLD' and `NEW' are not case sensitive.) In an
*Note `INSERT': insert. trigger, only `NEW.COL_NAME' can be used; there
is no old row. In a *Note `DELETE': delete. trigger, only
`OLD.COL_NAME' can be used; there is no new row. In an *Note `UPDATE':
update. trigger, you can use `OLD.COL_NAME' to refer to the columns of
a row before it is updated and `NEW.COL_NAME' to refer to the columns
of the row after it is updated.

A column named with `OLD' is read only. You can refer to it (if you
have the *Note `SELECT': select.  privilege), but not modify it. A
column named with `NEW' can be referred to if you have the `SELECT'
privilege for it. In a `BEFORE' trigger, you can also change its value
with `SET NEW.COL_NAME = VALUE' if you have the `UPDATE' privilege for
it. This means you can use a trigger to modify the values to be
inserted into a new row or that are used to update a row.

In a `BEFORE' trigger, the `NEW' value for an `AUTO_INCREMENT' column
is 0, not the automatically generated sequence number that will be
generated when the new record actually is inserted.

`OLD' and `NEW' are MySQL extensions to triggers.

By using the `BEGIN ... END' construct, you can define a trigger that
executes multiple statements. Within the `BEGIN' block, you also can
use other syntax that is allowed within stored routines such as
conditionals and loops.  However, just as for stored routines, if you
use the *Note `mysql': mysql. program to define a trigger that executes
multiple statements, it is necessary to redefine the *Note `mysql':
mysql. statement delimiter so that you can use the `;' statement
delimiter within the trigger definition. The following example
illustrates these points. It defines an *Note `UPDATE': update. trigger
that checks the new value to be used for updating each row, and
modifies the value to be within the range from 0 to 100. This must be a
`BEFORE' trigger because the value needs to be checked before it is
used to update the row:

     mysql> delimiter //
     mysql> CREATE TRIGGER upd_check BEFORE UPDATE ON account
         -> FOR EACH ROW
         -> BEGIN
         ->     IF NEW.amount < 0 THEN
         ->         SET NEW.amount = 0;
         ->     ELSEIF NEW.amount > 100 THEN
         ->         SET NEW.amount = 100;
         ->     END IF;
         -> END;//
     mysql> delimiter ;

It can be easier to define a stored procedure separately and then
invoke it from the trigger using a simple *Note `CALL': call.
statement. This is also advantageous if you want to invoke the same
routine from within several triggers.

There are some limitations on what can appear in statements that a
trigger executes when activated:

   * The trigger cannot use the *Note `CALL': call.  statement to
     invoke stored procedures that return data to the client or that
     use dynamic SQL. (Stored procedures are allowed to return data to
     the trigger through `OUT' or `INOUT' parameters.)

   * The trigger cannot use statements that explicitly or implicitly
     begin or end a transaction such as *Note `START TRANSACTION':
     commit, *Note `COMMIT': commit, or *Note `ROLLBACK': commit.

MySQL handles errors during trigger execution as follows:

   * If a `BEFORE' trigger fails, the operation on the corresponding
     row is not performed.

   * A `BEFORE' trigger is activated by the _attempt_ to insert or
     modify the row, regardless of whether the attempt subsequently
     succeeds.

   * An `AFTER' trigger is executed only if the `BEFORE' trigger (if
     any) and the row operation both execute successfully.

   * An error during either a `BEFORE' or `AFTER' trigger results in
     failure of the entire statement that caused trigger invocation.

   * For transactional tables, failure of a statement should cause
     rollback of all changes performed by the statement. Failure of a
     trigger causes the statement to fail, so trigger failure also
     causes rollback. For non-transactional tables, such rollback
     cannot be done, so although the statement fails, any changes
     performed prior to the point of the error remain in effect.


File: manual.info,  Node: trigger-metadata,  Prev: trigger-syntax,  Up: triggers

18.3.2 Trigger Metadata
-----------------------

Metadata about triggers can be obtained as follows:

   * Query the *Note `TRIGGERS': triggers-table. table of the
     `INFORMATION_SCHEMA' database. See *Note triggers-table::.

   * Use the *Note `SHOW TRIGGERS': show-triggers.  statement. See
     *Note show-triggers::.


File: manual.info,  Node: events,  Next: views,  Prev: triggers,  Up: stored-programs-views

18.4 Using the Event Scheduler
==============================

* Menu:

* events-overview::              Event Scheduler Overview
* events-configuration::         Event Scheduler Configuration
* events-syntax::                Event Syntax
* events-metadata::              Event Metadata
* events-status-info::           Event Scheduler Status
* events-privileges::            The Event Scheduler and MySQL Privileges

The _MySQL Event Scheduler_ manages the scheduling and execution of
events: Tasks that run according to schedule. The following discussion
covers the Event Scheduler and is divided into the following sections:

   * *Note events-overview::, provides an introduction to and
     conceptual overview of MySQL Events.

   * *Note events-syntax::, discusses the SQL statements for creating,
     altering, and dropping MySQL Events.

   * *Note events-metadata::, shows how to obtain information about
     events and how this information is stored by the MySQL Server.

   * *Note events-privileges::, discusses the privileges required to
     work with events and the ramifications that events have with
     regard to privileges when executing.

Stored routines require the `event' table in the `mysql' database. This
table is created during the MySQL 6.0 installation procedure. If you
are upgrading to MySQL 6.0 from an earlier version, be sure to update
your grant tables to make sure that the `event' table exists. See *Note
mysql-upgrade::.

*Additional resources*

   * You may find the MySQL Event Scheduler User Forum
     (http://forums.mysql.com/list.php?119) of use when working with
     scheduled events.

   * There are some restrictions on the use of events; see *Note
     stored-program-restrictions::.

   * Binary logging for events takes place as described in *Note
     stored-programs-logging::.


File: manual.info,  Node: events-overview,  Next: events-configuration,  Prev: events,  Up: events

18.4.1 Event Scheduler Overview
-------------------------------

MySQL Events are tasks that run according to a schedule.  Therefore, we
sometimes refer to them as _scheduled_ events. When you create an event,
you are creating a named database object containing one or more SQL
statements to be executed at one or more regular intervals, beginning
and ending at a specific date and time. Conceptually, this is similar
to the idea of the Unix `crontab' (also known as a `cron job') or the
Windows Task Scheduler.

Scheduled tasks of this type are also sometimes known as `temporal
triggers', implying that these are objects that are triggered by the
passage of time. While this is essentially correct, we prefer to use
the term _events_ in order to avoid confusion with triggers of the type
discussed in *Note triggers::.  Events should more specifically not be
confused with `temporary triggers'. Whereas a trigger is a database
object whose statements are executed in response to a specific type of
event that occurs on a given table, a (scheduled) event is an object
whose statements are executed in response to the passage of a specified
time interval.

While there is no provision in the SQL Standard for event scheduling,
there are precedents in other database systems, and you may notice some
similarities between these implementations and that found in the MySQL
Server.

MySQL Events have the following major features and properties:

   * In MySQL 6.0, an event is uniquely identified by its name and the
     schema to which it is assigned.

   * An event performs a specific action according to a schedule.  This
     action consists of an SQL statement, which can be a compound
     statement in a `BEGIN ... END' block if desired (see *Note
     sql-syntax-compound-statements::). An event's timing can be either
     _one-time_ or _recurrent_. A one-time event executes one time
     only. A recurrent event repeats its action at a regular interval,
     and the schedule for a recurring event can be assigned a specific
     start day and time, end day and time, both, or neither. (By
     default, a recurring event's schedule begins as soon as it is
     created, and continues indefinitely, until it is disabled or
     dropped.)

     If a repeating event does not terminate within its scheduling
     interval, the result may be multiple instances of the event
     executing simultaneously. If this is undesirable, you should
     institute a mechanism to prevent simultaneous instances. For
     example, you could use the `GET_LOCK()' function, or row or table
     locking.

   * Users can create, modify, and drop scheduled events using SQL
     statements intended for these purposes. Syntactically invalid
     event creation and modification statements fail with an
     appropriate error message. _A user may include statements in an
     event's action which require privileges that the user does not
     actually have_. The event creation or modification statement
     succeeds but the event's action fails. See *Note
     events-privileges:: for details.

   * Many of the properties of an event can be set or modified using
     SQL statements. These properties include the event's name, timing,
     persistence (that is, whether it is preserved following the
     expiration of its schedule), status (enabled or disabled), action
     to be performed, and the schema to which it is assigned. See *Note
     alter-event::.

     The default definer of an event is the user who created the event,
     unless the event has been altered, in which case the definer is
     the user who issued the last *Note `ALTER EVENT': alter-event.
     statement affecting that event. An event can be modified by any
     user having the `EVENT' privilege on the database for which the
     event is defined. See *Note events-privileges::.

   * An event's action statement may include most SQL statements
     permitted within stored routines. For restrictions, see *Note
     stored-program-restrictions::.


File: manual.info,  Node: events-configuration,  Next: events-syntax,  Prev: events-overview,  Up: events

18.4.2 Event Scheduler Configuration
------------------------------------

Events are executed by a special _event scheduler thread_; when we
refer to the Event Scheduler, we actually refer to this thread. When
running, the event scheduler thread and its current state can be seen
by users having the `PROCESS' privilege in the output of *Note `SHOW
PROCESSLIST': show-processlist, as shown in the discussion that follows.

The global `event_scheduler' system variable determines whether the
Event Scheduler is enabled and running on the server. In MySQL 6.0, it
has one of these 3 values, which affect event scheduling as described
here:

   * `OFF': The Event Scheduler is stopped. The event scheduler thread
     does not run, is not shown in the output of *Note `SHOW
     PROCESSLIST': show-processlist, and no scheduled events are
     executed. `OFF' is the default value for `event_scheduler'.

     When the Event Scheduler is stopped (`event_scheduler' is `OFF'),
     it can be started by setting the value of `event_scheduler' to
     `ON'. (See next item.)

   * `ON': The Event Scheduler is started; the event scheduler thread
     runs and executes all scheduled events.

     When the Event Scheduler is `ON', the event scheduler thread is
     listed in the output of *Note `SHOW PROCESSLIST':
     show-processlist. as a daemon process, and its state is
     represented as shown here:

          mysql> SHOW PROCESSLIST\G
          *************************** 1. row ***************************
               Id: 1
             User: root
             Host: localhost
               db: NULL
          Command: Query
             Time: 0
            State: NULL
             Info: show processlist
          *************************** 2. row ***************************
               Id: 2
             User: event_scheduler
             Host: localhost
               db: NULL
          Command: Daemon
             Time: 3
            State: Waiting for next activation
             Info: NULL
          2 rows in set (0.00 sec)

     Event scheduling can be stopped by setting the value of
     `event_scheduler' to `OFF'.

   * `DISABLED': This value renders the Event Scheduler
     non-operational. When the Event Scheduler is `DISABLED', the event
     scheduler thread does not run (and so does not appear in the
     output of *Note `SHOW PROCESSLIST': show-processlist.). In
     addition, the Event Scheduler state cannot be changed at runtime.

If the Event Scheduler status has not been set to `DISABLED',
`event_scheduler' can be toggled between `ON' and `OFF' (using *Note
`SET': set-option.). It is also possible to use `0' for `OFF', and `1'
for `ON' when setting this variable. Thus, any of the following 4
statements can be used in the *Note `mysql': mysql.  client to turn on
the Event Scheduler:

     SET GLOBAL event_scheduler = ON;
     SET @@global.event_scheduler = ON;
     SET GLOBAL event_scheduler = 1;
     SET @@global.event_scheduler = 1;

Similarly, any of these 4 statements can be used to turn off the Event
Scheduler:

     SET GLOBAL event_scheduler = OFF;
     SET @@global.event_scheduler = OFF;
     SET GLOBAL event_scheduler = 0;
     SET @@global.event_scheduler = 0;

Although `ON' and `OFF' have numeric equivalents, the value displayed
for `event_scheduler' by *Note `SELECT': select. or *Note `SHOW
VARIABLES': show-variables. is always one of `OFF', `ON', or `DISABLED'.
_`DISABLED' has no numeric equivalent_. For this reason, `ON' and `OFF'
are usually preferred over `1' and `0' when setting this variable.

Note that attempting to set `event_scheduler' without specifying it as
a global variable causes an error:

     mysql< SET @@event_scheduler = OFF;
     `ERROR 1229 (HY000): Variable 'event_scheduler' is a GLOBAL
     variable and should be set with SET GLOBAL'

*Important*:

It is possible to set the Event Scheduler to `DISABLED' only at server
startup. If `event_scheduler' is `ON' or `OFF', you cannot set it to
`DISABLED' at runtime. Also, if the Event Scheduler is set to
`DISABLED' at startup, you cannot change the value of `event_scheduler'
at runtime.

To disable the event scheduler, use one of the following two methods:

   * As a command-line option when starting the server:

          --event-scheduler=DISABLED

   * In the server configuration file (`my.cnf', or `my.ini' on Windows
     systems), include the line where it will be read by the server
     (for example, in a `[mysqld]' section):

          event_scheduler=DISABLED

To enable the Event Scheduler, restart the server without the
`--event-scheduler=DISABLED' command-line option, or after removing or
commenting out the line containing `event-scheduler=DISABLED' in the
server configuration file, as appropriate. Alternatively, you can use
`ON' (or `1') or `OFF' (or `0') in place of the `DISABLED' value when
starting the server.

*Note*:

You can issue event-manipulation statements when `event_scheduler' is
set to `DISABLED'. No warnings or errors are generated in such cases
(provided that the statements are themselves valid). However, scheduled
events cannot execute until this variable is set to `ON' (or `1'). Once
this has been done, the event scheduler thread executes all events
whose scheduling conditions are satisfied.

Starting the MySQL server with the `--skip-grant-tables' option causes
`event_scheduler' to be set to `DISABLED', overriding any other value
set either on the command line or in the `my.cnf' or `my.ini' file
(Bug#26807 (http://bugs.mysql.com/26807)).

For SQL statements used to create, alter, and drop events, see *Note
events-syntax::.

MySQL 6.0 provides an *Note `EVENTS': events-table. table in the
`INFORMATION_SCHEMA' database. This table can be queried to obtain
information about scheduled events which have been defined on the
server. See *Note events-metadata::, and *Note events-table::, for more
information.

For information regarding event scheduling and the MySQL privilege
system, see *Note events-privileges::.


File: manual.info,  Node: events-syntax,  Next: events-metadata,  Prev: events-configuration,  Up: events

18.4.3 Event Syntax
-------------------

MySQL 6.0 provides several SQL statements for working with scheduled
events:

   * New events are defined using the *Note `CREATE EVENT':
     create-event. statement. See *Note create-event::.

   * The definition of an existing event can be changed by means of the
     *Note `ALTER EVENT': alter-event. statement. See *Note
     alter-event::.

   * When a scheduled event is no longer wanted or needed, it can be
     deleted from the server by its definer using the *Note `DROP
     EVENT': drop-event. statement. See *Note drop-event::. Whether an
     event persists past the end of its schedule also depends on its `ON
     COMPLETION' clause, if it has one. See *Note create-event::.

     An event can be dropped by any user having the `EVENT' privilege
     for the database on which the event is defined. See *Note
     events-privileges::.


File: manual.info,  Node: events-metadata,  Next: events-status-info,  Prev: events-syntax,  Up: events

18.4.4 Event Metadata
---------------------

Metadata about events can be obtained as follows:

   * Query the *Note `EVENTS': events-table. table of the
     `INFORMATION_SCHEMA' database. See *Note events-table::.

   * Use the *Note `SHOW CREATE EVENT': show-create-event.  statement.
     See *Note show-create-event::.

   * Use the *Note `SHOW EVENTS': show-events. statement.  See *Note
     show-events::.


File: manual.info,  Node: events-status-info,  Next: events-privileges,  Prev: events-metadata,  Up: events

18.4.5 Event Scheduler Status
-----------------------------

The Event Scheduler writes information about event execution that
terminates with an error or warning to the MySQL Server's error log.
See *Note events-privileges:: for an example.  (Before MySQL 6.0.9, the
Event Scheduler also logged messages when events started execution and
terminated successfully.)

Information about the state of the Event Scheduler for debugging and
troubleshooting purposes can be obtained by running *Note `mysqladmin
debug': mysqladmin. (see *Note mysqladmin::); after running this
command, the server's error log contains output relating to the Event
Scheduler, similar to what is shown here:

     Events status:
     LLA = Last Locked At  LUA = Last Unlocked At
     WOC = Waiting On Condition  DL = Data Locked

     Event scheduler status:
     State      : INITIALIZED
     Thread id  : 0
     LLA        : init_scheduler:313
     LUA        : init_scheduler:318
     WOC        : NO
     Workers    : 0
     Executed   : 0
     Data locked: NO

     Event queue status:
     Element count   : 1
     Data locked     : NO
     Attempting lock : NO
     LLA             : init_queue:148
     LUA             : init_queue:168
     WOC             : NO
     Next activation : 0000-00-00 00:00:00

For `SELECT ... INTO VAR_LIST' statements, if the query returns no
rows, a warning with error code 1329 occurs (`No data'), and the
variable values remain unchanged. If the query returns multiple rows,
error 1172 occurs (`Result consisted of more than one row'). In the
context of such statements that occur as part of events executed by the
Event Scheduler, diagnostics messages (not only errors, but also
warnings) are written to the error log, and, on Windows, to the
application event log. For frequently executed events, it is possible
for this to result in many logged messages. For either condition, you
can avoid this problem by declaring a condition handler; see *Note
declare-handler::. For statements that may may retrieve multiple rows,
another strategy is to use `LIMIT 1' to limit the result set to a single
row.


File: manual.info,  Node: events-privileges,  Prev: events-status-info,  Up: events

18.4.6 The Event Scheduler and MySQL Privileges
-----------------------------------------------

To enable or disable the execution of scheduled events, it is necessary
to set the value of the global `event_scheduler' system variable.  This
requires the `SUPER' privilege.

The `EVENT' privilege governs the creation, modification, and deletion
of events. This privilege can be bestowed using *Note `GRANT': grant.
For example, this *Note `GRANT': grant. statement confers the `EVENT'
privilege for the schema named `myschema' on the user `jon@ghidora':

     GRANT EVENT ON myschema.* TO jon@ghidora;

(We assume that this user account already exists, and that we wish for
it to remain unchanged otherwise.)

To grant this same user the `EVENT' privilege on all schemas, use the
following statement:

     GRANT EVENT ON *.* TO jon@ghidora;

The `EVENT' privilege has global or schema-level scope. Therefore,
trying to grant it on a single table results in an error as shown:

     mysql> GRANT EVENT ON myschema.mytable TO jon@ghidora;
     `ERROR 1144 (42000): Illegal GRANT/REVOKE command; please
     consult the manual to see which privileges can be used'

It is important to understand that an event is executed with the
privileges of its definer, and that it cannot perform any actions for
which its definer does not have the requisite privileges. For example,
suppose that `jon@ghidora' has the `EVENT' privilege for `myschema'.
Suppose also that this user has the `SELECT' privilege for `myschema',
but no other privileges for this schema. It is possible for
`jon@ghidora' to create a new event such as this one:

     CREATE EVENT e_store_ts
         ON SCHEDULE
           EVERY 10 SECOND
         DO
           INSERT INTO myschema.mytable VALUES (UNIX_TIMESTAMP());

The user waits for a minute or so, and then performs a `SELECT * FROM
mytable;' query, expecting to see several new rows in the table.
Instead, the table is empty. Since the user does not have the `INSERT'
privilege for the table in question, the event has no effect.

If you inspect the MySQL error log (`HOSTNAME.err'), you can see that
the event is executing, but the action it is attempting to perform
fails, as indicated by `RetCode=0':

     060209 22:39:44 [Note]     EVEX EXECUTING event newdb.e [EXPR:10]
     060209 22:39:44 [Note]     EVEX EXECUTED event newdb.e  [EXPR:10]. RetCode=0
     060209 22:39:54 [Note]     EVEX EXECUTING event newdb.e [EXPR:10]
     060209 22:39:54 [Note]     EVEX EXECUTED event newdb.e  [EXPR:10]. RetCode=0
     060209 22:40:04 [Note]     EVEX EXECUTING event newdb.e [EXPR:10]
     060209 22:40:04 [Note]     EVEX EXECUTED event newdb.e  [EXPR:10]. RetCode=0

Since this user very likely does not have access to the error log, it
is possible to verify whether the event's action statement is valid by
executing it directly:

     mysql> INSERT INTO myschema.mytable VALUES (UNIX_TIMESTAMP());
     `ERROR 1142 (42000): INSERT command denied to user
     'jon'@'ghidora' for table 'mytable''

Inspection of the *Note `INFORMATION_SCHEMA.EVENTS': events-table.
table shows that `e_store_ts' exists and is enabled, but its
`LAST_EXECUTED' column is `NULL':

     mysql> SELECT * FROM INFORMATION_SCHEMA.EVENTS
          >     WHERE EVENT_NAME='e_store_ts'
          >     AND EVENT_SCHEMA='myschema'\G
     *************************** 1. row ***************************
        EVENT_CATALOG: NULL
         EVENT_SCHEMA: myschema
           EVENT_NAME: e_store_ts
              DEFINER: jon@ghidora
           EVENT_BODY: SQL
     EVENT_DEFINITION: INSERT INTO myschema.mytable VALUES (UNIX_TIMESTAMP())
           EVENT_TYPE: RECURRING
           EXECUTE_AT: NULL
       INTERVAL_VALUE: 5
       INTERVAL_FIELD: SECOND
             SQL_MODE: NULL
               STARTS: 0000-00-00 00:00:00
                 ENDS: 0000-00-00 00:00:00
               STATUS: ENABLED
        ON_COMPLETION: NOT PRESERVE
              CREATED: 2006-02-09 22:36:06
         LAST_ALTERED: 2006-02-09 22:36:06
        LAST_EXECUTED: NULL
        EVENT_COMMENT:
     1 row in set (0.00 sec)

To rescind the `EVENT' privilege, use the *Note `REVOKE': revoke.
statement. In this example, the `EVENT' privilege on the schema
`myschema' is removed from the `jon@ghidora' user account:

     REVOKE EVENT ON myschema.* FROM jon@ghidora;

*Important*:

Revoking the `EVENT' privilege from a user does not delete or disable
any events that may have been created by that user.

An event is not migrated or dropped as a result of renaming or dropping
the user who created it.

For example, suppose that the user `jon@ghidora' has been granted the
`EVENT' and `INSERT' privileges on the `myschema' schema. This user
then creates the following event:

     CREATE EVENT e_insert
         ON SCHEDULE
           EVERY 7 SECOND
         DO
           INSERT INTO myschema.mytable;

After this event has been created, `root' revokes the `EVENT' privilege
for `jon@ghidora'. However, `e_insert' continues to execute, inserting
a new row into `mytable' each seven seconds. The same would be true if
`root' had issued either of these statements:

   * `DROP USER jon@ghidora;'

   * `RENAME USER jon@ghidora TO someotherguy@ghidora;'

You can verify that this is true by examining the `mysql.event' table
(discussed later in this section) or the *Note
`INFORMATION_SCHEMA.EVENTS': events-table. table (see *Note
events-table::) before and after issuing a *Note `DROP USER':
drop-user. or *Note `RENAME USER': rename-user. statement.

Event definitions are stored in the `mysql.event' table. To drop an
event created by another user account, the MySQL `root' user (or
another user with the necessary privileges) can delete rows from this
table. For example, to remove the event `e_insert' shown previously,
`root' can use the following statement:

     DELETE FROM mysql.event
         WHERE db = 'myschema'
           AND definer = 'jon@ghidora'
           AND name = 'e_insert';

It is very important to match the event name, database schema name, and
user account when deleting rows from the `mysql.event' table. This is
because the same user can create different events of the same name in
different schemas.

Users' `EVENT' privileges are stored in the `Event_priv' columns of the
`mysql.user' and `mysql.db' tables. In both cases, this column holds
one of the values '`Y'' or '`N''.  '`N'' is the default.
`mysql.user.Event_priv' is set to '`Y'' for a given user only if that
user has the global `EVENT' privilege (that is, if the privilege was
bestowed using `GRANT EVENT ON *.*'). For a schema-level `EVENT'
privilege, *Note `GRANT': grant. creates a row in `mysql.db' and sets
that row's `Db' column to the name of the schema, the `User' column to
the name of the user, and the `Event_priv' column to '`Y''.  There
should never be any need to manipulate these tables directly, since the
*Note `GRANT EVENT': grant. and `REVOKE EVENT' statements perform the
required operations on them.

Five status variables provide counts of event-related operations (but
_not_ of statements executed by events; see *Note
stored-program-restrictions::). These are:

   * `Com_create_event': The number of *Note `CREATE EVENT':
     create-event. statements executed since the last server restart.

   * `Com_alter_event': The number of *Note `ALTER EVENT': alter-event.
     statements executed since the last server restart.

   * `Com_drop_event': The number of *Note `DROP EVENT': drop-event.
     statements executed since the last server restart.

   * `Com_show_create_event': The number of *Note `SHOW CREATE EVENT':
     show-create-event. statements executed since the last server
     restart.

   * `Com_show_events': The number of *Note `SHOW EVENTS': show-events.
     statements executed since the last server restart.

You can view current values for all of these at one time by running the
statement `SHOW STATUS LIKE '%event%';'.


File: manual.info,  Node: views,  Next: stored-programs-logging,  Prev: events,  Up: stored-programs-views

18.5 Using Views
================

* Menu:

* view-syntax::                  View Syntax
* view-algorithms::              View Processing Algorithms
* view-updatability::            Updatable and Insertable Views
* view-metadata::                View Metadata

Views (including updatable views) are available in MySQL Server 6.0.
Views are stored queries that when invoked produce a result set. A view
acts as a virtual table.

To use views if you have upgraded to MySQL 6.0 from an older release
that did not support views, you should upgrade your grant tables so
that they contain the view-related privileges. See *Note
mysql-upgrade::.

The following discussion describes the syntax for creating and dropping
views, and shows some examples of how to use them.

*Additional resources*

   * You may find the Views User Forum
     (http://forums.mysql.com/list.php?100) of use when working with
     views.

   * For answers to some commonly asked questions regarding views in
     MySQL, see *Note faqs-views::.

   * There are some restrictions on the use of views; see *Note
     view-restrictions::.


File: manual.info,  Node: view-syntax,  Next: view-algorithms,  Prev: views,  Up: views

18.5.1 View Syntax
------------------

The *Note `CREATE VIEW': create-view. statement creates a new view (see
*Note create-view::). To alter the definition of a view or drop a view,
use *Note `ALTER VIEW': alter-view. (see *Note alter-view::), or *Note
`DROP VIEW': drop-view. (see *Note drop-view::).

A view can be created from many kinds of *Note `SELECT': select.
statements. It can refer to base tables or other views. It can use
joins, *Note `UNION': union, and subqueries. The *Note `SELECT':
select. need not even refer to any tables. The following example
defines a view that selects two columns from another table, as well as
an expression calculated from those columns:

     mysql> CREATE TABLE t (qty INT, price INT);
     mysql> INSERT INTO t VALUES(3, 50), (5, 60);
     mysql> CREATE VIEW v AS SELECT qty, price, qty*price AS value FROM t;
     mysql> SELECT * FROM v;
     +------+-------+-------+
     | qty  | price | value |
     +------+-------+-------+
     |    3 |    50 |   150 |
     |    5 |    60 |   300 |
     +------+-------+-------+
     mysql> SELECT * FROM v WHERE qty = 5;
     +------+-------+-------+
     | qty  | price | value |
     +------+-------+-------+
     |    5 |    60 |   300 |
     +------+-------+-------+


File: manual.info,  Node: view-algorithms,  Next: view-updatability,  Prev: view-syntax,  Up: views

18.5.2 View Processing Algorithms
---------------------------------

The optional `ALGORITHM' clause for *Note `CREATE VIEW': create-view. or
*Note `ALTER VIEW': alter-view. is a MySQL extension to standard SQL.
It affects how MySQL processes the view.  `ALGORITHM' takes three
values: `MERGE', `TEMPTABLE', or `UNDEFINED'. The default algorithm is
`UNDEFINED' if no `ALGORITHM' clause is present.

For `MERGE', the text of a statement that refers to the view and the
view definition are merged such that parts of the view definition
replace corresponding parts of the statement.

For `TEMPTABLE', the results from the view are retrieved into a
temporary table, which then is used to execute the statement.

For `UNDEFINED', MySQL chooses which algorithm to use. It prefers
`MERGE' over `TEMPTABLE' if possible, because `MERGE' is usually more
efficient and because a view cannot be updatable if a temporary table
is used.

A reason to choose `TEMPTABLE' explicitly is that locks can be released
on underlying tables after the temporary table has been created and
before it is used to finish processing the statement. This might result
in quicker lock release than the `MERGE' algorithm so that other
clients that use the view are not blocked as long.

A view algorithm can be `UNDEFINED' for three reasons:

   * No `ALGORITHM' clause is present in the *Note `CREATE VIEW':
     create-view. statement.

   * The *Note `CREATE VIEW': create-view. statement has an explicit
     `ALGORITHM = UNDEFINED' clause.

   * `ALGORITHM = MERGE' is specified for a view that can be processed
     only with a temporary table. In this case, MySQL generates a
     warning and sets the algorithm to `UNDEFINED'.

As mentioned earlier, `MERGE' is handled by merging corresponding parts
of a view definition into the statement that refers to the view. The
following examples briefly illustrate how the `MERGE' algorithm works.
The examples assume that there is a view `v_merge' that has this
definition:

     CREATE ALGORITHM = MERGE VIEW v_merge (vc1, vc2) AS
     SELECT c1, c2 FROM t WHERE c3 > 100;

Example 1: Suppose that we issue this statement:

     SELECT * FROM v_merge;

MySQL handles the statement as follows:

   * `v_merge' becomes `t'

   * `*' becomes `vc1, vc2', which corresponds to `c1, c2'

   * The view `WHERE' clause is added

The resulting statement to be executed becomes:

     SELECT c1, c2 FROM t WHERE c3 > 100;

Example 2: Suppose that we issue this statement:

     SELECT * FROM v_merge WHERE vc1 < 100;

This statement is handled similarly to the previous one, except that
`vc1 < 100' becomes `c1 < 100' and the view `WHERE' clause is added to
the statement `WHERE' clause using an `AND' connective (and parentheses
are added to make sure the parts of the clause are executed with
correct precedence). The resulting statement to be executed becomes:

     SELECT c1, c2 FROM t WHERE (c3 > 100) AND (c1 < 100);

Effectively, the statement to be executed has a `WHERE' clause of this
form:

     WHERE (select WHERE) AND (view WHERE)

If the `MERGE' algorithm cannot be used, a temporary table must be used
instead. `MERGE' cannot be used if the view contains any of the
following constructs:

   * Aggregate functions (`SUM()', `MIN()', `MAX()', `COUNT()', and so
     forth)

   * `DISTINCT'

   * `GROUP BY'

   * `HAVING'

   * `LIMIT'

   * *Note `UNION': union. or *Note `UNION ALL': union.

   * Subquery in the select list

   * Refers only to literal values (in this case, there is no
     underlying table)


File: manual.info,  Node: view-updatability,  Next: view-metadata,  Prev: view-algorithms,  Up: views

18.5.3 Updatable and Insertable Views
-------------------------------------

Some views are updatable. That is, you can use them in statements such
as *Note `UPDATE': update, *Note `DELETE': delete, or *Note `INSERT':
insert. to update the contents of the underlying table. For a view to
be updatable, there must be a one-to-one relationship between the rows
in the view and the rows in the underlying table. There are also
certain other constructs that make a view non-updatable. To be more
specific, a view is not updatable if it contains any of the following:

   * Aggregate functions (`SUM()', `MIN()', `MAX()', `COUNT()', and so
     forth)

   * `DISTINCT'

   * `GROUP BY'

   * `HAVING'

   * *Note `UNION': union. or *Note `UNION ALL': union.

   * Subquery in the select list

   * Certain joins (see additional join discussion later in this
     section)

   * Non-updatable view in the `FROM' clause

   * A subquery in the `WHERE' clause that refers to a table in the
     `FROM' clause

   * Refers only to literal values (in this case, there is no
     underlying table to update)

   * Uses `ALGORITHM = TEMPTABLE' (use of a temporary table always
     makes a view non-updatable)

   * Multiple references to any column of a base table.

With respect to insertability (being updatable with *Note `INSERT':
insert. statements), an updatable view is insertable if it also
satisfies these additional requirements for the view columns:

   * There must be no duplicate view column names.

   * The view must contain all columns in the base table that do not
     have a default value.

   * The view columns must be simple column references and not derived
     columns. A derived column is one that is not a simple column
     reference but is derived from an expression. These are examples of
     derived columns:

          3.14159
          col1 + 3
          UPPER(col2)
          col3 / col4
          (SUBQUERY)

A view that has a mix of simple column references and derived columns
is not insertable, but it can be updatable if you update only those
columns that are not derived. Consider this view:

     CREATE VIEW v AS SELECT col1, 1 AS col2 FROM t;

This view is not insertable because `col2' is derived from an
expression. But it is updatable if the update does not try to update
`col2'. This update is allowable:

     UPDATE v SET col1 = 0;

This update is not allowable because it attempts to update a derived
column:

     UPDATE v SET col2 = 0;

It is sometimes possible for a multiple-table view to be updatable,
assuming that it can be processed with the `MERGE' algorithm. For this
to work, the view must use an inner join (not an outer join or a *Note
`UNION': union.). Also, only a single table in the view definition can
be updated, so the `SET' clause must name only columns from one of the
tables in the view. Views that use *Note `UNION ALL': union. are
disallowed even though they might be theoretically updatable, because
the implementation uses temporary tables to process them.

For a multiple-table updatable view, *Note `INSERT': insert. can work
if it inserts into a single table. *Note `DELETE': delete. is not
supported.

*Note `INSERT DELAYED': insert-delayed. is not supported for views.

If a table contains an `AUTO_INCREMENT' column, inserting into an
insertable view on the table that does not include the `AUTO_INCREMENT'
column does not change the value of `LAST_INSERT_ID()', because the side
effects of inserting default values into columns not part of the view
should not be visible.

The `WITH CHECK OPTION' clause can be given for an updatable view to
prevent inserts or updates to rows except those for which the `WHERE'
clause in the SELECT_STATEMENT is true.

In a `WITH CHECK OPTION' clause for an updatable view, the `LOCAL' and
`CASCADED' keywords determine the scope of check testing when the view
is defined in terms of another view. The `LOCAL' keyword restricts the
`CHECK OPTION' only to the view being defined. `CASCADED' causes the
checks for underlying views to be evaluated as well. When neither
keyword is given, the default is `CASCADED'. Consider the definitions
for the following table and set of views:

     mysql> CREATE TABLE t1 (a INT);
     mysql> CREATE VIEW v1 AS SELECT * FROM t1 WHERE a < 2
         -> WITH CHECK OPTION;
     mysql> CREATE VIEW v2 AS SELECT * FROM v1 WHERE a > 0
         -> WITH LOCAL CHECK OPTION;
     mysql> CREATE VIEW v3 AS SELECT * FROM v1 WHERE a > 0
         -> WITH CASCADED CHECK OPTION;

Here the `v2' and `v3' views are defined in terms of another view, `v1'.
`v2' has a `LOCAL' check option, so inserts are tested only against the
`v2' check. `v3' has a `CASCADED' check option, so inserts are tested
not only against its own check, but against those of underlying views.
The following statements illustrate these differences:

     mysql> INSERT INTO v2 VALUES (2);
     Query OK, 1 row affected (0.00 sec)
     mysql> INSERT INTO v3 VALUES (2);
     ERROR 1369 (HY000): CHECK OPTION failed 'test.v3'

MySQL sets a flag, called the view updatability flag, at *Note `CREATE
VIEW': create-view. time. The flag is set to `YES' (true) if *Note
`UPDATE': update. and *Note `DELETE': delete. (and similar operations)
are legal for the view. Otherwise, the flag is set to `NO' (false). The
`IS_UPDATABLE' column in the *Note `INFORMATION_SCHEMA.VIEWS':
views-table. table displays the status of this flag. It means that the
server always knows whether a view is updatable. If the view is not
updatable, statements such *Note `UPDATE': update, *Note `DELETE':
delete, and *Note `INSERT': insert. are illegal and will be rejected.
(Note that even if a view is updatable, it might not be possible to
insert into it, as described elsewhere in this section.)

The updatability of views may be affected by the value of the
`updatable_views_with_limit' system variable. See *Note
server-system-variables::.


File: manual.info,  Node: view-metadata,  Prev: view-updatability,  Up: views

18.5.4 View Metadata
--------------------

Metadata about views can be obtained as follows:

   * Query the *Note `VIEWS': views-table. table of the
     `INFORMATION_SCHEMA' database. See *Note views-table::.

   * Use the *Note `SHOW CREATE VIEW': show-create-view.  statement.
     See *Note show-create-view::.


File: manual.info,  Node: stored-programs-logging,  Prev: views,  Up: stored-programs-views

18.6 Binary Logging of Stored Programs
======================================

The binary log contains information about SQL statements that modify
database contents. This information is stored in the form of `events'
that describe the modifications. The binary log has two important
purposes:

   * For replication, the binary log is used on master replication
     servers as a record of the statements to be sent to slave servers.
     The master server sends the events contained in its binary log to
     its slaves, which execute those events to make the same data
     changes that were made on the master. See *Note
     replication-implementation::.

   * Certain data recovery operations require use of the binary log.
     After a backup file has been restored, the events in the binary
     log that were recorded after the backup was made are re-executed.
     These events bring databases up to date from the point of the
     backup. See *Note recovery-from-backups::.

However, there are certain binary logging issues that apply with
respect to stored programs (stored procedures and functions, triggers,
and events), if logging occurs at the statement level:

   * In some cases, it is possible that a statement will affect
     different sets of rows on a master and a slave.

   * Replicated statements executed on a slave are processed by the
     slave SQL thread, which has full privileges. It is possible for a
     procedure to follow different execution paths on master and slave
     servers, so a user can write a routine containing a dangerous
     statement that will execute only on the slave where it is
     processed by a thread that has full privileges.

   * If a stored program that modifies data is non-deterministic, it is
     not repeatable. This can result in different data on a master and
     slave, or cause restored data to differ from the original data.

This section describes how MySQL 6.0 handles binary logging for stored
programs. It states the current conditions that the implementation
places on the use of stored programs, and what you can do to avoid
problems. It also provides additional information about the reasons for
these conditions.

In general, the issues described here result when binary logging occurs
at the SQL statement level. If you use row-based binary logging, the
log contains changes made to individual rows as a result of executing
SQL statements. When routines or triggers execute, row changes are
logged, not the statements that make the changes. For stored
procedures, this means that the *Note `CALL': call. statement is not
logged. For stored functions, row changes made within the function are
logged, not the function invocation. For triggers, row changes made by
the trigger are logged. On the slave side, only the row changes are
seen, not the stored program invocation. For general information about
row-based logging, see *Note replication-formats::.

Unless noted otherwise, the remarks here assume that you have enabled
binary logging by starting the server with the `--log-bin' option. (See
*Note binary-log::.) If the binary log is not enabled, replication is
not possible, nor is the binary log available for data recovery.

The current conditions on the use of stored functions in MySQL 6.0 can
be summarized as follows. These conditions do not apply to stored
procedures or Event Scheduler events and they do not apply unless
binary logging is enabled.

   * To create or alter a stored function, you must have the `SUPER'
     privilege, in addition to the `CREATE ROUTINE' or `ALTER ROUTINE'
     privilege that is normally required.

   * When you create a stored function, you must declare either that it
     is deterministic or that it does not modify data.  Otherwise, it
     may be unsafe for data recovery or replication.

     By default, for a *Note `CREATE FUNCTION': create-function.
     statement to be accepted, at least one of `DETERMINISTIC', `NO
     SQL', or `READS SQL DATA' must be specified explicitly. Otherwise
     an error occurs:

          ERROR 1418 (HY000): This function has none of DETERMINISTIC, NO SQL,
          or READS SQL DATA in its declaration and binary logging is enabled
          (you *might* want to use the less safe log_bin_trust_function_creators
          variable)

     This function is deterministic (and does not modify data), so it
     is safe:

          CREATE FUNCTION f1(i INT)
          RETURNS INT
          DETERMINISTIC
          READS SQL DATA
          BEGIN
            RETURN i;
          END;

     This function uses `UUID()', which is not deterministic, so the
     function also is not deterministic and is not safe:

          CREATE FUNCTION f2()
          RETURNS CHAR(36) CHARACTER SET utf8
          BEGIN
            RETURN UUID();
          END;

     This function modifies data, so it may not be safe:

          CREATE FUNCTION f3(p_id INT)
          RETURNS INT
          BEGIN
            UPDATE t SET modtime = NOW() WHERE id = p_id;
            RETURN ROW_COUNT();
          END;

     Assessment of the nature of a function is based on the `honesty'
     of the creator: MySQL does not check that a function declared
     `DETERMINISTIC' is free of statements that produce
     non-deterministic results.

   * Although it is possible to create a deterministic stored function
     without specifying `DETERMINISTIC', you cannot execute this
     function using statement-based binary logging. To execute such a
     function, you must use row-based or mixed binary logging.
     Alternatively, if you explicitly specify `DETERMINISTIC' in the
     function definition, you can use any kind of logging, including
     statement-based logging.

   * To relax the preceding conditions on function creation (that you
     must have the `SUPER' privilege and that a function must be
     declared deterministic or to not modify data), set the global
     `log_bin_trust_function_creators' system variable to 1. By
     default, this variable has a value of 0, but you can change it
     like this:

          mysql> SET GLOBAL log_bin_trust_function_creators = 1;

     You can also set this variable by using the
     `--log-bin-trust-function-creators=1' option when starting the
     server.

     If binary logging is not enabled, `log_bin_trust_function_creators'
     does not apply and `SUPER' is not required for function creation.

   * For information about built-in functions that may be unsafe for
     replication (and thus cause stored functions that use them to be
     unsafe as well), see *Note replication-features::.

Triggers are similar to stored functions, so the preceding remarks
regarding functions also apply to triggers with the following
exception: *Note `CREATE TRIGGER': create-trigger. does not have an
optional `DETERMINISTIC' characteristic, so triggers are assumed to be
always deterministic. However, this assumption might in some cases be
invalid. For example, the `UUID()' function is non-deterministic (and
does not replicate). You should be careful about using such functions
in triggers.

Triggers can update tables, so error messages similar to those for
stored functions occur with *Note `CREATE TRIGGER': create-trigger. if
you do not have the required privileges. On the slave side, the slave
uses the trigger `DEFINER' attribute to determine which user is
considered to be the creator of the trigger.

The rest of this section provides additional detail about the logging
implementation and its implications. You need not read it unless you
are interested in the background on the rationale for the current
logging-related conditions on stored routine use. This discussion
applies only for statement-based logging, and not for row-based
logging, with the exception of the first item: `CREATE' and `DROP'
statements are logged as statements regardless of the logging mode.

   * The server writes *Note `CREATE EVENT': create-event, *Note
     `CREATE PROCEDURE': create-procedure, *Note `CREATE FUNCTION':
     create-function, *Note `ALTER EVENT': alter-event, *Note `ALTER
     PROCEDURE': alter-procedure, *Note `ALTER FUNCTION':
     alter-function, *Note `DROP EVENT': drop-event, *Note `DROP
     PROCEDURE': drop-procedure, and *Note `DROP FUNCTION':
     drop-function. statements to the binary log.

   * A stored function invocation is logged as a *Note `SELECT':
     select. statement if the function changes data and occurs within a
     statement that would not otherwise be logged. This prevents
     non-replication of data changes that result from use of stored
     functions in non-logged statements. For example, *Note `SELECT':
     select.  statements are not written to the binary log, but a *Note
     `SELECT': select. might invoke a stored function that makes
     changes. To handle this, a `SELECT FUNC_NAME()' statement is
     written to the binary log when the given function makes a change.
     Suppose that the following statements are executed on the master:

          CREATE FUNCTION f1(a INT) RETURNS INT
          BEGIN
            IF (a < 3) THEN
              INSERT INTO t2 VALUES (a);
            END IF;
            RETURN 0;
          END;

          CREATE TABLE t1 (a INT);
          INSERT INTO t1 VALUES (1),(2),(3);

          SELECT f1(a) FROM t1;

     When the *Note `SELECT': select. statement executes, the function
     `f1()' is invoked three times. Two of those invocations insert a
     row, and MySQL logs a *Note `SELECT': select. statement for each
     of them. That is, MySQL writes the following statements to the
     binary log:

          SELECT f1(1);
          SELECT f1(2);

     The server also logs a *Note `SELECT': select.  statement for a
     stored function invocation when the function invokes a stored
     procedure that causes an error. In this case, the server writes
     the *Note `SELECT': select.  statement to the log along with the
     expected error code. On the slave, if the same error occurs, that
     is the expected result and replication continues. Otherwise,
     replication stops.

   * Logging stored function invocations rather than the statements
     executed by a function has a security implication for replication,
     which arises from two factors:

        * It is possible for a function to follow different execution
          paths on master and slave servers.

        * Statements executed on a slave are processed by the slave SQL
          thread which has full privileges.

     The implication is that although a user must have the `CREATE
     ROUTINE' privilege to create a function, the user can write a
     function containing a dangerous statement that will execute only
     on the slave where it is processed by a thread that has full
     privileges. For example, if the master and slave servers have
     server ID values of 1 and 2, respectively, a user on the master
     server could create and invoke an unsafe function `unsafe_func()'
     as follows:

          mysql> delimiter //
          mysql> CREATE FUNCTION unsafe_func () RETURNS INT
              -> BEGIN
              ->   IF @@server_id=2 THEN DANGEROUS_STATEMENT; END IF;
              ->   RETURN 1;
              -> END;
              -> //
          mysql> delimiter ;
          mysql> INSERT INTO t VALUES(unsafe_func());

     The *Note `CREATE FUNCTION': create-function. and *Note `INSERT':
     insert. statements are written to the binary log, so the slave
     will execute them. Because the slave SQL thread has full
     privileges, it will execute the dangerous statement. Thus, the
     function invocation has different effects on the master and slave
     and is not replication-safe.

     To guard against this danger for servers that have binary logging
     enabled, stored function creators must have the `SUPER' privilege,
     in addition to the usual `CREATE ROUTINE' privilege that is
     required. Similarly, to use *Note `ALTER FUNCTION':
     alter-function, you must have the `SUPER' privilege in addition to
     the `ALTER ROUTINE' privilege.  Without the `SUPER' privilege, an
     error will occur:

          ERROR 1419 (HY000): You do not have the SUPER privilege and
          binary logging is enabled (you *might* want to use the less safe
          log_bin_trust_function_creators variable)

     If you do not want to require function creators to have the
     `SUPER' privilege (for example, if all users with the `CREATE
     ROUTINE' privilege on your system are experienced application
     developers), set the global `log_bin_trust_function_creators'
     system variable to 1. You can also set this variable by using the
     `--log-bin-trust-function-creators=1' option when starting the
     server. If binary logging is not enabled,
     `log_bin_trust_function_creators' does not apply and `SUPER' is not
     required for function creation.

   * If a function that performs updates is non-deterministic, it is
     not repeatable. This can have two undesirable effects:

        * It will make a slave different from the master.

        * Restored data will be different from the original data.

     To deal with these problems, MySQL enforces the following
     requirement: On a master server, creation and alteration of a
     function is refused unless you declare the function to be
     deterministic or to not modify data. Two sets of function
     characteristics apply here:

        * The `DETERMINISTIC' and `NOT DETERMINISTIC' characteristics
          indicate whether a function always produces the same result
          for given inputs.  The default is `NOT DETERMINISTIC' if
          neither characteristic is given. To declare that a function
          is deterministic, you must specify `DETERMINISTIC' explicitly.

        * The `CONTAINS SQL', `NO SQL', `READS SQL DATA', and `MODIFIES
          SQL DATA' characteristics provide information about whether
          the function reads or writes data. Either `NO SQL' or `READS
          SQL DATA' indicates that a function does not change data, but
          you must specify one of these explicitly because the default
          is `CONTAINS SQL' if no characteristic is given.

     By default, for a *Note `CREATE FUNCTION': create-function.
     statement to be accepted, at least one of `DETERMINISTIC', `NO
     SQL', or `READS SQL DATA' must be specified explicitly. Otherwise
     an error occurs:

          ERROR 1418 (HY000): This function has none of DETERMINISTIC, NO SQL,
          or READS SQL DATA in its declaration and binary logging is enabled
          (you *might* want to use the less safe log_bin_trust_function_creators
          variable)

     If you set `log_bin_trust_function_creators' to 1, the requirement
     that functions be deterministic or not modify data is dropped.

   * Stored procedure calls are logged at the statement level rather
     than at the *Note `CALL': call. level.  That is, the server does
     not log the *Note `CALL': call. statement, it logs those
     statements within the procedure that actually execute. As a
     result, the same changes that occur on the master will be observed
     on slave servers. This prevents problems that could result from a
     procedure having different execution paths on different machines.

     In general, statements executed within a stored procedure are
     written to the binary log using the same rules that would apply
     were the statements to be executed in standalone fashion. Some
     special care is taken when logging procedure statements because
     statement execution within procedures is not quite the same as in
     non-procedure context:

        * A statement to be logged might contain references to local
          procedure variables. These variables do not exist outside of
          stored procedure context, so a statement that refers to such
          a variable cannot be logged literally. Instead, each
          reference to a local variable is replaced by this construct
          for logging purposes:

               NAME_CONST(VAR_NAME, VAR_VALUE)

          VAR_NAME is the local variable name, and VAR_VALUE is a
          constant indicating the value that the variable has at the
          time the statement is logged.  `NAME_CONST()' has a value of
          VAR_VALUE, and a `name' of VAR_NAME. Thus, if you invoke this
          function directly, you get a result like this:

               mysql> SELECT NAME_CONST('myname', 14);
               +--------+
               | myname |
               +--------+
               |     14 |
               +--------+

          `NAME_CONST()' allows a logged standalone statement to be
          executed on a slave with the same effect as the original
          statement that was executed on the master within a stored
          procedure.

        * A statement to be logged might contain references to
          user-defined variables. To handle this, MySQL writes a *Note
          `SET': set-option.  statement to the binary log to make sure
          that the variable exists on the slave with the same value as
          on the master.  For example, if a statement refers to a
          variable `@my_var', that statement will be preceded in the
          binary log by the following statement, where VALUE is the
          value of `@my_var' on the master:

               SET @my_var = VALUE;

        * Procedure calls can occur within a committed or rolled-back
          transaction. Transactional context is accounted for so that
          the transactional aspects of procedure execution are
          replicated correctly. That is, the server logs those
          statements within the procedure that actually execute and
          modify data, and also logs *Note `BEGIN': commit, *Note
          `COMMIT': commit, and *Note `ROLLBACK': commit.  statements
          as necessary. For example, if a procedure updates only
          transactional tables and is executed within a transaction
          that is rolled back, those updates are not logged. If the
          procedure occurs within a committed transaction, *Note
          `BEGIN': commit.  and *Note `COMMIT': commit. statements are
          logged with the updates. For a procedure that executes within
          a rolled-back transaction, its statements are logged using
          the same rules that would apply if the statements were
          executed in standalone fashion:

             * Updates to transactional tables are not logged.

             * Updates to non-transactional tables are logged because
               rollback does not cancel them.

             * Updates to a mix of transactional and non-transactional
               tables are logged surrounded by *Note `BEGIN': commit.
               and *Note `ROLLBACK': commit.  so that slaves will make
               the same changes and rollbacks as on the master.

   * A stored procedure call is _not_ written to the binary log at the
     statement level if the procedure is invoked from within a stored
     function. In that case, the only thing logged is the statement
     that invokes the function (if it occurs within a statement that is
     logged) or a *Note `DO': do. statement (if it occurs within a
     statement that is not logged). For this reason, care should be
     exercised in the use of stored functions that invoke a procedure,
     even if the procedure is otherwise safe in itself.


File: manual.info,  Node: information-schema,  Next: connectors-apis,  Prev: stored-programs-views,  Up: Top

19 `INFORMATION_SCHEMA' Tables
******************************

* Menu:

* schemata-table::               The `INFORMATION_SCHEMA SCHEMATA' Table
* tables-table::                 The `INFORMATION_SCHEMA TABLES' Table
* columns-table::                The `INFORMATION_SCHEMA COLUMNS' Table
* statistics-table::             The `INFORMATION_SCHEMA STATISTICS' Table
* user-privileges-table::        The `INFORMATION_SCHEMA USER_PRIVILEGES' Table
* schema-privileges-table::      The `INFORMATION_SCHEMA SCHEMA_PRIVILEGES' Table
* table-privileges-table::       The `INFORMATION_SCHEMA TABLE_PRIVILEGES' Table
* column-privileges-table::      The `INFORMATION_SCHEMA COLUMN_PRIVILEGES' Table
* character-sets-table::         The `INFORMATION_SCHEMA CHARACTER_SETS' Table
* collations-table::             The `INFORMATION_SCHEMA COLLATIONS' Table
* collation-character-set-applicability-table::  The `INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY' Table
* table-constraints-table::      The `INFORMATION_SCHEMA TABLE_CONSTRAINTS' Table
* key-column-usage-table::       The `INFORMATION_SCHEMA KEY_COLUMN_USAGE' Table
* routines-table::               The `INFORMATION_SCHEMA ROUTINES' Table
* views-table::                  The `INFORMATION_SCHEMA VIEWS' Table
* triggers-table::               The `INFORMATION_SCHEMA TRIGGERS' Table
* plugins-table::                The `INFORMATION_SCHEMA PLUGINS' Table
* engines-table::                The `INFORMATION_SCHEMA ENGINES' Table
* partitions-table::             The `INFORMATION_SCHEMA PARTITIONS' Table
* events-table::                 The `INFORMATION_SCHEMA EVENTS' Table
* files-table::                  The `INFORMATION_SCHEMA FILES' Table
* tablespaces-table::            The `INFORMATION_SCHEMA TABLESPACES' Table
* processlist-table::            The `INFORMATION_SCHEMA PROCESSLIST' Table
* referential-constraints-table::  The `INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS' Table
* status-table::                 The `INFORMATION_SCHEMA GLOBAL_STATUS' and `SESSION_STATUS' Tables
* variables-table::              The `INFORMATION_SCHEMA GLOBAL_VARIABLES' and `SESSION_VARIABLES' Tables
* parameters-table::             The `INFORMATION_SCHEMA PARAMETERS' Table
* profiling-table::              The `INFORMATION_SCHEMA PROFILING' Table
* other-information-schema-tables::  Other `INFORMATION_SCHEMA' Tables
* extended-show::                Extensions to `SHOW' Statements

`INFORMATION_SCHEMA' provides access to database metadata.

_Metadata_ is data about the data, such as the name of a database or
table, the data type of a column, or access privileges. Other terms
that sometimes are used for this information are _data dictionary_ and
_system catalog_.

`INFORMATION_SCHEMA' is the information database, the place that stores
information about all the other databases that the MySQL server
maintains. Inside `INFORMATION_SCHEMA' there are several read-only
tables. They are actually views, not base tables, so there are no files
associated with them.

In effect, we have a database named `INFORMATION_SCHEMA', although the
server does not create a database directory with that name. It is
possible to select `INFORMATION_SCHEMA' as the default database with a
*Note `USE': use. statement, but it is possible only to read the
contents of tables. You cannot insert into them, update them, or delete
from them.

Here is an example of a statement that retrieves information from
`INFORMATION_SCHEMA':

     mysql> SELECT table_name, table_type, engine
         -> FROM information_schema.tables
         -> WHERE table_schema = 'db5'
         -> ORDER BY table_name DESC;
     +------------+------------+--------+
     | table_name | table_type | engine |
     +------------+------------+--------+
     | v56        | VIEW       | NULL   |
     | v3         | VIEW       | NULL   |
     | v2         | VIEW       | NULL   |
     | v          | VIEW       | NULL   |
     | tables     | BASE TABLE | MyISAM |
     | t7         | BASE TABLE | MyISAM |
     | t3         | BASE TABLE | MyISAM |
     | t2         | BASE TABLE | MyISAM |
     | t          | BASE TABLE | MyISAM |
     | pk         | BASE TABLE | InnoDB |
     | loop       | BASE TABLE | MyISAM |
     | kurs       | BASE TABLE | MyISAM |
     | k          | BASE TABLE | MyISAM |
     | into       | BASE TABLE | MyISAM |
     | goto       | BASE TABLE | MyISAM |
     | fk2        | BASE TABLE | InnoDB |
     | fk         | BASE TABLE | InnoDB |
     +------------+------------+--------+
     17 rows in set (0.01 sec)

Explanation: The statement requests a list of all the tables in
database `db5', in reverse alphabetical order, showing just three
pieces of information: the name of the table, its type, and its storage
engine.

Each MySQL user has the right to access these tables, but can see only
the rows in the tables that correspond to objects for which the user
has the proper access privileges. In some cases (for example, the
`ROUTINE_DEFINITION' column in the *Note `INFORMATION_SCHEMA.ROUTINES':
routines-table. table), users who have insufficient privileges will see
`NULL'.

The `SELECT ... FROM INFORMATION_SCHEMA' statement is intended as a
more consistent way to provide access to the information provided by
the various *Note `SHOW': show. statements that MySQL supports (*Note
`SHOW DATABASES': show-databases, *Note `SHOW TABLES': show-tables, and
so forth). Using *Note `SELECT': select. has these advantages, compared
to *Note `SHOW': show.:

   * It conforms to Codd's rules. That is, all access is done on tables.

   * Nobody needs to learn a new statement syntax. Because they already
     know how *Note `SELECT': select. works, they only need to learn
     the object names.

   * The implementor need not worry about adding keywords.

   * There are millions of possible output variations, instead of just
     one. This provides more flexibility for applications that have
     varying requirements about what metadata they need.

   * Migration is easier because every other DBMS does it this way.

However, because *Note `SHOW': show. is popular with MySQL employees
and users, and because it might be confusing were it to disappear, the
advantages of conventional syntax are not a sufficient reason to
eliminate *Note `SHOW': show.  In fact, along with the implementation of
`INFORMATION_SCHEMA', there are enhancements to *Note `SHOW': show. as
well. These are described in *Note extended-show::.

There is no difference between the privileges required for *Note
`SHOW': show. statements and those required to select information from
`INFORMATION_SCHEMA'. In either case, you have to have some privilege
on an object in order to see information about it.

The implementation for the `INFORMATION_SCHEMA' table structures in
MySQL follows the ANSI/ISO SQL:2003 standard Part 11 `Schemata'. Our
intent is approximate compliance with SQL:2003 core feature F021 `Basic
information schema'.

Users of SQL Server 2000 (which also follows the standard) may notice a
strong similarity. However, MySQL has omitted many columns that are not
relevant for our implementation, and added columns that are
MySQL-specific. One such column is the `ENGINE' column in the *Note
`INFORMATION_SCHEMA.TABLES': tables-table.  table.

Although other DBMSs use a variety of names, like `syscat' or `system',
the standard name is `INFORMATION_SCHEMA'.

The following sections describe each of the tables and columns that are
in `INFORMATION_SCHEMA'. For each column, there are three pieces of
information:

   * ``INFORMATION_SCHEMA' Name' indicates the name for the column in
     the `INFORMATION_SCHEMA' table. This corresponds to the standard
     SQL name unless the `Remarks' field says `MySQL extension.'

   * `*Note `SHOW': show. Name' indicates the equivalent field name in
     the closest *Note `SHOW': show. statement, if there is one.

   * `Remarks' provides additional information where applicable. If
     this field is `NULL', it means that the value of the column is
     always `NULL'.  If this field says `MySQL extension,' the column is
     a MySQL extension to standard SQL.

To avoid using any name that is reserved in the standard or in DB2, SQL
Server, or Oracle, we changed the names of some columns marked `MySQL
extension'. (For example, we changed `COLLATION' to `TABLE_COLLATION'
in the *Note `TABLES': tables-table. table.) See the list of reserved
words near the end of this article:
`http://web.archive.org/web/20070409075643rn_1/www.dbazine.com/db2/db2-disarticles/gulutzan5'.

The definition for character columns (for example, `TABLES.TABLE_NAME')
is generally `VARCHAR(N) CHARACTER SET utf8' where N is at least 64.
MySQL uses the default collation for this character set
(`utf8_general_ci') for all searches, sorts, comparisons, and other
string operations on such columns. If the default collation is not
correct for your needs, you can force a suitable collation with a
`COLLATE' clause (*Note charset-collate::).

Each section indicates what *Note `SHOW': show.  statement is
equivalent to a *Note `SELECT': select.  that retrieves information from
`INFORMATION_SCHEMA', if there is such a statement.  For *Note `SHOW':
show. statements that display information for the current database if
you omit a `FROM DB_NAME' clause, you can often select information for
the current database by adding an `AND TABLE_SCHEMA = CURRENT_SCHEMA()'
condition to the `WHERE' clause of a query that retrieves information
from an `INFORMATION_SCHEMA' table.

*Note*:

At present, there are some missing columns and some columns out of
order. We are working on this and updating the documentation as changes
are made.

For answers to questions that are often asked concerning the
`INFORMATION_SCHEMA' database, see *Note faqs-information-schema::.


File: manual.info,  Node: schemata-table,  Next: tables-table,  Prev: information-schema,  Up: information-schema

19.1 The `INFORMATION_SCHEMA SCHEMATA' Table
============================================

A schema is a database, so the *Note `SCHEMATA': schemata-table. table
provides information about databases.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`CATALOG_NAME'                                       `def'
`SCHEMA_NAME'                                        Database
`DEFAULT_CHARACTER_SET_NAME'                         
`DEFAULT_COLLATION_NAME'                             
`SQL_PATH'                                           `NULL'

The following statements are equivalent:

     SELECT SCHEMA_NAME AS `Database`
       FROM INFORMATION_SCHEMA.SCHEMATA
       [WHERE SCHEMA_NAME LIKE 'WILD']

     SHOW DATABASES
       [LIKE 'WILD']


File: manual.info,  Node: tables-table,  Next: columns-table,  Prev: schemata-table,  Up: information-schema

19.2 The `INFORMATION_SCHEMA TABLES' Table
==========================================

The *Note `TABLES': tables-table. table provides information about
tables in databases.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`TABLE_CATALOG'                                      `def'
`TABLE_SCHEMA'                `Table_'...            
`TABLE_NAME'                  `Table_'...            
`TABLE_TYPE'                                         
`ENGINE'                      `Engine'               MySQL extension
`VERSION'                     `Version'              The version number of
                                                     the table's `.frm'
                                                     file, MySQL extension
`ROW_FORMAT'                  `Row_format'           MySQL extension
`TABLE_ROWS'                  `Rows'                 MySQL extension
`AVG_ROW_LENGTH'              `Avg_row_length'       MySQL extension
`DATA_LENGTH'                 `Data_length'          MySQL extension
`MAX_DATA_LENGTH'             `Max_data_length'      MySQL extension
`INDEX_LENGTH'                `Index_length'         MySQL extension
`DATA_FREE'                   `Data_free'            MySQL extension
`AUTO_INCREMENT'              `Auto_increment'       MySQL extension
`CREATE_TIME'                 `Create_time'          MySQL extension
`UPDATE_TIME'                 `Update_time'          MySQL extension
`CHECK_TIME'                  `Check_time'           MySQL extension
`TABLE_COLLATION'             `Collation'            MySQL extension
`CHECKSUM'                    `Checksum'             MySQL extension
`CREATE_OPTIONS'              `Create_options'       MySQL extension
`TABLE_COMMENT'               `Comment'              MySQL extension

*Notes*:

   * `TABLE_SCHEMA' and `TABLE_NAME' are a single field in a *Note
     `SHOW': show. display, for example `Table_in_db1'.

   * `TABLE_TYPE' should be `BASE TABLE' or `VIEW'. Currently, the
     *Note `TABLES': tables-table. table does not list `TEMPORARY'
     tables.

   * For partitioned tables, the `ENGINE' column shows the name of the
     storage engine used by all partitions.  (Previously, this column
     showed `PARTITION' for such tables.)

   * The `TABLE_ROWS' column is `NULL' if the table is in the
     `INFORMATION_SCHEMA' database. For `InnoDB' tables, the row count
     is only a rough estimate used in SQL optimization.

   * Beginning with MySQL 6.0.6, the `DATA_FREE' column shows the free
     space in bytes for `InnoDB' tables.

   * We have nothing for the table's default character set.
     `TABLE_COLLATION' is close, because collation names begin with a
     character set name.

   * The `CREATE_OPTIONS' column shows `partitioned' if the table is
     partitioned.

The following statements are equivalent:

     SELECT table_name FROM INFORMATION_SCHEMA.TABLES
       WHERE table_schema = 'DB_NAME'
       [AND table_name LIKE 'WILD']

     SHOW TABLES
       FROM DB_NAME
       [LIKE 'WILD']


File: manual.info,  Node: columns-table,  Next: statistics-table,  Prev: tables-table,  Up: information-schema

19.3 The `INFORMATION_SCHEMA COLUMNS' Table
===========================================

The *Note `COLUMNS': columns-table. table provides information about
columns in tables.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`TABLE_CATALOG'                                      `def'
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`COLUMN_NAME'                 `Field'                
`ORDINAL_POSITION'                                   see notes
`COLUMN_DEFAULT'              `Default'              
`IS_NULLABLE'                 `Null'                 
`DATA_TYPE'                   `Type'                 
`CHARACTER_MAXIMUM_LENGTH'    `Type'                 
`CHARACTER_OCTET_LENGTH'                             
`NUMERIC_PRECISION'           `Type'                 
`NUMERIC_SCALE'               `Type'                 
`CHARACTER_SET_NAME'                                 
`COLLATION_NAME'              `Collation'            
`COLUMN_TYPE'                 `Type'                 MySQL extension
`COLUMN_KEY'                  `Key'                  MySQL extension
`EXTRA'                       `Extra'                MySQL extension
`PRIVILEGES'                  `Privileges'           MySQL extension
`COLUMN_COMMENT'              `Comment'              MySQL extension
`STORAGE'                     `Column storage type'  MySQL extension
`FORMAT'                      `Column storage        MySQL extension
                              format'                

*Notes*:

   * In *Note `SHOW': show, the `Type' display includes values from
     several different *Note `COLUMNS': columns-table. columns.

   * `ORDINAL_POSITION' is necessary because you might want to say
     `ORDER BY ORDINAL_POSITION'. Unlike *Note `SHOW': show, *Note
     `SELECT': select. does not have automatic ordering.

   * `CHARACTER_OCTET_LENGTH' should be the same as
     `CHARACTER_MAXIMUM_LENGTH', except for multi-byte character sets.

   * `CHARACTER_SET_NAME' can be derived from `Collation'. For example,
     if you say `SHOW FULL COLUMNS FROM t', and you see in the
     `Collation' column a value of `latin1_swedish_ci', the character
     set is what is before the first underscore: `latin1'.

   * `STORAGE' and `FORMAT' apply to `NDB' tables.  `STORAGE' indicates
     whether a column is stored on disk or memory, and `FORMAT'
     indicates the column storage format (*Note `FIXED': numeric-types,
     `DYNAMIC', or `DEFAULT').

The following statements are nearly equivalent:

     SELECT COLUMN_NAME, DATA_TYPE, IS_NULLABLE, COLUMN_DEFAULT
       FROM INFORMATION_SCHEMA.COLUMNS
       WHERE table_name = 'TBL_NAME'
       [AND table_schema = 'DB_NAME']
       [AND column_name LIKE 'WILD']

     SHOW COLUMNS
       FROM TBL_NAME
       [FROM DB_NAME]
       [LIKE 'WILD']


File: manual.info,  Node: statistics-table,  Next: user-privileges-table,  Prev: columns-table,  Up: information-schema

19.4 The `INFORMATION_SCHEMA STATISTICS' Table
==============================================

The *Note `STATISTICS': statistics-table. table provides information
about table indexes.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`TABLE_CATALOG'                                      `def'
`TABLE_SCHEMA'                                       = Database
`TABLE_NAME'                  `Table'                
`NON_UNIQUE'                  `Non_unique'           
`INDEX_SCHEMA'                                       = Database
`INDEX_NAME'                  `Key_name'             
`SEQ_IN_INDEX'                `Seq_in_index'         
`COLUMN_NAME'                 `Column_name'          
`COLLATION'                   `Collation'            
`CARDINALITY'                 `Cardinality'          
`SUB_PART'                    `Sub_part'             MySQL extension
`PACKED'                      `Packed'               MySQL extension
`NULLABLE'                    `Null'                 MySQL extension
`INDEX_TYPE'                  `Index_type'           MySQL extension
`COMMENT'                     `Comment'              MySQL extension
`INDEX_COMMENT'               `Comment'              MySQL extension

*Notes*:

   * There is no standard table for indexes. The preceding list is
     similar to what SQL Server 2000 returns for `sp_statistics',
     except that we replaced the name `QUALIFIER' with `CATALOG' and we
     replaced the name `OWNER' with `SCHEMA'.

     Clearly, the preceding table and the output from *Note `SHOW
     INDEX': show-index. are derived from the same parent. So the
     correlation is already close.

   * The `INDEX_COMMENT' column indicates any comment provided for the
     index with a `COMMENT' attribute when the index was created.

The following statements are equivalent:

     SELECT * FROM INFORMATION_SCHEMA.STATISTICS
       WHERE table_name = 'TBL_NAME'
       AND table_schema = 'DB_NAME'

     SHOW INDEX
       FROM TBL_NAME
       FROM DB_NAME


File: manual.info,  Node: user-privileges-table,  Next: schema-privileges-table,  Prev: statistics-table,  Up: information-schema

19.5 The `INFORMATION_SCHEMA USER_PRIVILEGES' Table
===================================================

The *Note `USER_PRIVILEGES': user-privileges-table. table provides
information about global privileges. This information comes from the
`mysql.user' grant table.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`GRANTEE'                                            `'USER_NAME'@'HOST_NAME''
                                                     value, MySQL extension
`TABLE_CATALOG'                                      `def', MySQL extension
`PRIVILEGE_TYPE'                                     MySQL extension
`IS_GRANTABLE'                                       MySQL extension

*Notes*:

   * This is a non-standard table. It takes its values from the
     `mysql.user' table.


File: manual.info,  Node: schema-privileges-table,  Next: table-privileges-table,  Prev: user-privileges-table,  Up: information-schema

19.6 The `INFORMATION_SCHEMA SCHEMA_PRIVILEGES' Table
=====================================================

The *Note `SCHEMA_PRIVILEGES': schema-privileges-table. table provides
information about schema (database) privileges. This information comes
from the `mysql.db' grant table.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`GRANTEE'                                            `'USER_NAME'@'HOST_NAME''
                                                     value, MySQL extension
`TABLE_CATALOG'                                      `def', MySQL extension
`TABLE_SCHEMA'                                       MySQL extension
`PRIVILEGE_TYPE'                                     MySQL extension
`IS_GRANTABLE'                                       MySQL extension

*Notes*:

   * This is a non-standard table. It takes its values from the
     `mysql.db' table.


File: manual.info,  Node: table-privileges-table,  Next: column-privileges-table,  Prev: schema-privileges-table,  Up: information-schema

19.7 The `INFORMATION_SCHEMA TABLE_PRIVILEGES' Table
====================================================

The *Note `TABLE_PRIVILEGES': table-privileges-table. table provides
information about table privileges. This information comes from the
`mysql.tables_priv' grant table.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`GRANTEE'                                            `'USER_NAME'@'HOST_NAME''
                                                     value
`TABLE_CATALOG'                                      `def'
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`PRIVILEGE_TYPE'                                     
`IS_GRANTABLE'                                       

*Notes*:

   * `PRIVILEGE_TYPE' can contain one (and only one) of these values:
     `SELECT', `INSERT', `UPDATE', `REFERENCES', `ALTER', `INDEX',
     `DROP', `CREATE VIEW'.

The following statements are _not_ equivalent:

     SELECT ... FROM INFORMATION_SCHEMA.TABLE_PRIVILEGES

     SHOW GRANTS ...


File: manual.info,  Node: column-privileges-table,  Next: character-sets-table,  Prev: table-privileges-table,  Up: information-schema

19.8 The `INFORMATION_SCHEMA COLUMN_PRIVILEGES' Table
=====================================================

The *Note `COLUMN_PRIVILEGES': column-privileges-table. table provides
information about column privileges. This information comes from the
`mysql.columns_priv' grant table.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`GRANTEE'                                            `'USER_NAME'@'HOST_NAME''
                                                     value
`TABLE_CATALOG'                                      `def'
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`COLUMN_NAME'                                        
`PRIVILEGE_TYPE'                                     
`IS_GRANTABLE'                                       

*Notes*:

   * In the output from *Note `SHOW FULL COLUMNS': show-columns, the
     privileges are all in one field and in lowercase, for example,
     `select,insert,update,references'. In *Note `COLUMN_PRIVILEGES':
     column-privileges-table, there is one privilege per row, in
     uppercase.

   * `PRIVILEGE_TYPE' can contain one (and only one) of these values:
     `SELECT', `INSERT', `UPDATE', `REFERENCES'.

   * If the user has `GRANT OPTION' privilege, `IS_GRANTABLE' should be
     `YES'. Otherwise, `IS_GRANTABLE' should be `NO'. The output does
     not list `GRANT OPTION' as a separate privilege.

The following statements are _not_ equivalent:

     SELECT ... FROM INFORMATION_SCHEMA.COLUMN_PRIVILEGES

     SHOW GRANTS ...


File: manual.info,  Node: character-sets-table,  Next: collations-table,  Prev: column-privileges-table,  Up: information-schema

19.9 The `INFORMATION_SCHEMA CHARACTER_SETS' Table
==================================================

The *Note `CHARACTER_SETS': character-sets-table. table provides
information about available character sets.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`CHARACTER_SET_NAME'          `Charset'              
`DEFAULT_COLLATE_NAME'        `Default collation'    
`DESCRIPION'                  `Description'          MySQL extension
`MAXLEN'                      `Maxlen'               MySQL extension

The following statements are equivalent:

     SELECT * FROM INFORMATION_SCHEMA.CHARACTER_SETS
       [WHERE name LIKE 'WILD']

     SHOW CHARACTER SET
       [LIKE 'WILD']


File: manual.info,  Node: collations-table,  Next: collation-character-set-applicability-table,  Prev: character-sets-table,  Up: information-schema

19.10 The `INFORMATION_SCHEMA COLLATIONS' Table
===============================================

The *Note `COLLATIONS': collations-table. table provides information
about collations for each character set.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`COLLATION_NAME'              `Collation'            
`CHARACTER_SET_NAME'          `Charset'              MySQL extension
`ID'                          `Id'                   MySQL extension
`IS_DEFAULT'                  `Default'              MySQL extension
`IS_COMPILED'                 `Compiled'             MySQL extension
`SORTLEN'                     `Sortlen'              MySQL extension

The following statements are equivalent:

     SELECT COLLATION_NAME FROM INFORMATION_SCHEMA.COLLATIONS
       [WHERE collation_name LIKE 'WILD']

     SHOW COLLATION
       [LIKE 'WILD']


File: manual.info,  Node: collation-character-set-applicability-table,  Next: table-constraints-table,  Prev: collations-table,  Up: information-schema

19.11 The `INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY' Table
==========================================================================

The *Note `COLLATION_CHARACTER_SET_APPLICABILITY':
collation-character-set-applicability-table.  table indicates what
character set is applicable for what collation. The columns are
equivalent to the first two display fields that we get from *Note `SHOW
COLLATION': show-collation.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`COLLATION_NAME'              `Collation'            
`CHARACTER_SET_NAME'          `Charset'              


File: manual.info,  Node: table-constraints-table,  Next: key-column-usage-table,  Prev: collation-character-set-applicability-table,  Up: information-schema

19.12 The `INFORMATION_SCHEMA TABLE_CONSTRAINTS' Table
======================================================

The *Note `TABLE_CONSTRAINTS': table-constraints-table. table describes
which tables have constraints.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`CONSTRAINT_CATALOG'                                 `def'
`CONSTRAINT_SCHEMA'                                  
`CONSTRAINT_NAME'                                    
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`CONSTRAINT_TYPE'                                    

*Notes*:

   * The `CONSTRAINT_TYPE' value can be `UNIQUE', `PRIMARY KEY', or
     `FOREIGN KEY'.

   * The `UNIQUE' and `PRIMARY KEY' information is about the same as
     what you get from the `Key_name' field in the output from *Note
     `SHOW INDEX': show-index. when the `Non_unique' field is `0'.

   * The `CONSTRAINT_TYPE' column can contain one of these values:
     `UNIQUE', `PRIMARY KEY', `FOREIGN KEY', `CHECK'. This is a *Note
     `CHAR': char. (not *Note `ENUM': enum.) column. The `CHECK' value
     is not available until we support `CHECK'.


File: manual.info,  Node: key-column-usage-table,  Next: routines-table,  Prev: table-constraints-table,  Up: information-schema

19.13 The `INFORMATION_SCHEMA KEY_COLUMN_USAGE' Table
=====================================================

The *Note `KEY_COLUMN_USAGE': key-column-usage-table. table describes
which key columns have constraints.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`CONSTRAINT_CATALOG'                                 `def'
`CONSTRAINT_SCHEMA'                                  
`CONSTRAINT_NAME'                                    
`TABLE_CATALOG'                                      `def'
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`COLUMN_NAME'                                        
`ORDINAL_POSITION'                                   
`POSITION_IN_UNIQUE_CONSTRAINT'                       
`REFERENCED_TABLE_SCHEMA'                            
`REFERENCED_TABLE_NAME'                              
`REFERENCED_COLUMN_NAME'                             

*Notes*:

   * If the constraint is a foreign key, then this is the column of the
     foreign key, not the column that the foreign key references.

   * The value of `ORDINAL_POSITION' is the column's position within
     the constraint, not the column's position within the table. Column
     positions are numbered beginning with 1.

   * The value of `POSITION_IN_UNIQUE_CONSTRAINT' is `NULL' for unique
     and primary-key constraints. For foreign-key constraints, it is
     the ordinal position in key of the table that is being referenced.

     For example, suppose that there are two tables name `t1' and `t3'
     that have the following definitions:

          CREATE TABLE t1
          (
              s1 INT,
              s2 INT,
              s3 INT,
              PRIMARY KEY(s3)
          ) ENGINE=InnoDB;

          CREATE TABLE t3
          (
              s1 INT,
              s2 INT,
              s3 INT,
              KEY(s1),
              CONSTRAINT CO FOREIGN KEY (s2) REFERENCES t1(s3)
          ) ENGINE=InnoDB;

     For those two tables, the *Note `KEY_COLUMN_USAGE':
     key-column-usage-table. table has two rows:

        * One row with `CONSTRAINT_NAME' = `'PRIMARY'', `TABLE_NAME' =
          `'t1'', `COLUMN_NAME' = `'s3'', `ORDINAL_POSITION' = `1',
          `POSITION_IN_UNIQUE_CONSTRAINT' = `NULL'.

        * One row with `CONSTRAINT_NAME' = `'CO'', `TABLE_NAME' =
          `'t3'', `COLUMN_NAME' = `'s2'', `ORDINAL_POSITION' = `1',
          `POSITION_IN_UNIQUE_CONSTRAINT' = `1'.


File: manual.info,  Node: routines-table,  Next: views-table,  Prev: key-column-usage-table,  Up: information-schema

19.14 The `INFORMATION_SCHEMA ROUTINES' Table
=============================================

The *Note `ROUTINES': routines-table. table provides information about
stored routines (both procedures and functions).  The *Note `ROUTINES':
routines-table. table does not include user-defined functions (UDFs) at
this time.

The column named ``mysql.proc' name' indicates the `mysql.proc' table
column that corresponds to the *Note `INFORMATION_SCHEMA.ROUTINES':
routines-table. table column, if any.

*`INFORMATION_SCHEMA' Name*   *`mysql.proc' Name*    *Remarks*
`SPECIFIC_NAME'               `specific_name'        
`ROUTINE_CATALOG'                                    `def'
`ROUTINE_SCHEMA'              `db'                   
`ROUTINE_NAME'                `name'                 
`ROUTINE_TYPE'                `type'                 `{PROCEDURE|FUNCTION}'
`DATA_TYPE'                                          same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`CHARACTER_MAXIMUM_LENGTH'                           same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`CHARACTER_OCTET_LENGTH'                             same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`NUMERIC_PRECISION'                                  same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`NUMERIC_SCALE'                                      same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`CHARACTER_SET_NAME'                                 same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`COLLATION_NAME'                                     same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`DTD_IDENTIFIER'                                     data type descriptor
`ROUTINE_BODY'                                       `SQL'
`ROUTINE_DEFINITION'          `body'                 
`EXTERNAL_NAME'                                      `NULL'
`EXTERNAL_LANGUAGE'           `language'             `NULL'
`PARAMETER_STYLE'                                    `SQL'
`IS_DETERMINISTIC'            `is_deterministic'     
`SQL_DATA_ACCESS'             `sql_data_access'      
`SQL_PATH'                                           `NULL'
`SECURITY_TYPE'               `security_type'        
`CREATED'                     `created'              
`LAST_ALTERED'                `modified'             
`SQL_MODE'                    `sql_mode'             MySQL extension
`ROUTINE_COMMENT'             `comment'              MySQL extension
`DEFINER'                     `definer'              MySQL extension
`CHARACTER_SET_CLIENT'                               MySQL extension
`COLLATION_CONNECTION'                               MySQL extension
`DATABASE_COLLATION'                                 MySQL extension

*Notes*:

   * MySQL calculates `EXTERNAL_LANGUAGE' thus:

        * If `mysql.proc.language='SQL'', `EXTERNAL_LANGUAGE' is `NULL'

        * Otherwise, `EXTERNAL_LANGUAGE' is what is in
          `mysql.proc.language'. However, we do not have external
          languages yet, so it is always `NULL'.

   * `CHARACTER_SET_CLIENT' is the session value of the
     `character_set_client' system variable when the routine was
     created.  `COLLATION_CONNECTION' is the session value of the
     `collation_connection' system variable when the routine was
     created.  `DATABASE_COLLATION' is the collation of the database
     with which the routine is associated.

   * The `DATA_TYPE', `CHARACTER_MAXIMUM_LENGTH',
     `CHARACTER_OCTET_LENGTH', `NUMERIC_PRECISION', `NUMERIC_SCALE',
     `CHARACTER_SET_NAME', and `COLLATION_NAME' columns provide
     information about the data type for the `RETURNS' clause of stored
     functions. If a stored routine is a stored procedure, these
     columns all are `NULL'.  These columns were added in MySQL 5.2.6.

     Information about stored function `RETURNS' data types is also
     available in the *Note `PARAMETERS': parameters-table. table. The
     return value data type row for a function can be identified as the
     row that has an `ORDINAL_POSITION' value of 0.


File: manual.info,  Node: views-table,  Next: triggers-table,  Prev: routines-table,  Up: information-schema

19.15 The `INFORMATION_SCHEMA VIEWS' Table
==========================================

The *Note `VIEWS': views-table. table provides information about views
in databases. You must have the `SHOW VIEW' privilege to access this
table.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`TABLE_CATALOG'                                      `def'
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`VIEW_DEFINITION'                                    
`CHECK_OPTION'                                       
`IS_UPDATABLE'                                       
`DEFINER'                                            
`SECURITY_TYPE'                                      
`CHARACTER_SET_CLIENT'                               MySQL extension
`COLLATION_CONNECTION'                               MySQL extension

*Notes*:

   * The `VIEW_DEFINITION' column has most of what you see in the
     `Create Table' field that *Note `SHOW CREATE VIEW':
     show-create-view. produces. Skip the words before *Note `SELECT':
     select. and skip the words `WITH CHECK OPTION'. Suppose that the
     original statement was:

          CREATE VIEW v AS
            SELECT s2,s1 FROM t
            WHERE s1 > 5
            ORDER BY s1
            WITH CHECK OPTION;

     Then the view definition looks like this:

          SELECT s2,s1 FROM t WHERE s1 > 5 ORDER BY s1

   * The `CHECK_OPTION' column has a value of `NONE', `CASCADE', or
     `LOCAL'.

   * MySQL sets a flag, called the view updatability flag, at *Note
     `CREATE VIEW': create-view. time. The flag is set to `YES' (true)
     if *Note `UPDATE': update. and *Note `DELETE': delete. (and
     similar operations) are legal for the view. Otherwise, the flag is
     set to `NO' (false). The `IS_UPDATABLE' column in the *Note
     `VIEWS': views-table. table displays the status of this flag. It
     means that the server always knows whether a view is updatable. If
     the view is not updatable, statements such *Note `UPDATE': update,
     *Note `DELETE': delete, and *Note `INSERT': insert. are illegal
     and will be rejected. (Note that even if a view is updatable, it
     might not be possible to insert into it; for details, refer to
     *Note create-view::.)

   * The `DEFINER' column indicates who defined the view.
     `SECURITY_TYPE' has a value of `DEFINER' or `INVOKER'.

   * `CHARACTER_SET_CLIENT' is the session value of the
     `character_set_client' system variable when the view was created.
     `COLLATION_CONNECTION' is the session value of the
     `collation_connection' system variable when the view was created.

MySQL lets you use different `sql_mode' settings to tell the server the
type of SQL syntax to support. For example, you might use the `ANSI'
SQL mode to ensure MySQL correctly interprets the standard SQL
concatenation operator, the double bar (`||'), in your queries.  If you
then create a view that concatenates items, you might worry that
changing the `sql_mode' setting to a value different from `ANSI' could
cause the view to become invalid. But this is not the case. No matter
how you write out a view definition, MySQL always stores it the same
way, in a canonical form. Here is an example that shows how the server
changes a double bar concatenation operator to a `CONCAT()' function:

     mysql> SET sql_mode = 'ANSI';
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE VIEW test.v AS SELECT 'a' || 'b' as col1;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT VIEW_DEFINITION FROM INFORMATION_SCHEMA.VIEWS
         -> WHERE TABLE_SCHEMA = 'test' AND TABLE_NAME = 'v';
     +----------------------------------+
     | VIEW_DEFINITION                  |
     +----------------------------------+
     | select concat('a','b') AS `col1` |
     +----------------------------------+
     1 row in set (0.00 sec)

The advantage of storing a view definition in canonical form is that
changes made later to the value of `sql_mode' will not affect the
results from the view. However an additional consequence is that
comments prior to *Note `SELECT': select. are stripped from the
definition by the server.


File: manual.info,  Node: triggers-table,  Next: plugins-table,  Prev: views-table,  Up: information-schema

19.16 The `INFORMATION_SCHEMA TRIGGERS' Table
=============================================

The *Note `TRIGGERS': triggers-table. table provides information about
triggers. You must have the `TRIGGER' privilege to access this table.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`TRIGGER_CATALOG'                                    `def'
`TRIGGER_SCHEMA'                                     
`TRIGGER_NAME'                `Trigger'              
`EVENT_MANIPULATION'          `Event'                
`EVENT_OBJECT_CATALOG'                               `def'
`EVENT_OBJECT_SCHEMA'                                
`EVENT_OBJECT_TABLE'          `Table'                
`ACTION_ORDER'                                       `0'
`ACTION_CONDITION'                                   `NULL'
`ACTION_STATEMENT'            `Statement'            
`ACTION_ORIENTATION'                                 `ROW'
`ACTION_TIMING'               `Timing'               
`ACTION_REFERENCE_OLD_TABLE'                         `NULL'
`ACTION_REFERENCE_NEW_TABLE'                         `NULL'
`ACTION_REFERENCE_OLD_ROW'                           `OLD'
`ACTION_REFERENCE_NEW_ROW'                           `NEW'
`CREATED'                                            `NULL' (`0')
`SQL_MODE'                                           MySQL extension
`DEFINER'                                            MySQL extension
`CHARACTER_SET_CLIENT'                               MySQL extension
`COLLATION_CONNECTION'                               MySQL extension
`DATABASE_COLLATION'                                 MySQL extension

*Notes*:

   * The `TRIGGER_SCHEMA' and `TRIGGER_NAME' columns contain the name of
     the database in which the trigger occurs and the trigger name,
     respectively.

   * The `EVENT_MANIPULATION' column contains one of the values
     `'INSERT'', `'DELETE'', or `'UPDATE''.

   * As noted in *Note triggers::, every trigger is associated with
     exactly one table. The `EVENT_OBJECT_SCHEMA' and
     `EVENT_OBJECT_TABLE' columns contain the database in which this
     table occurs, and the table's name.

   * The `ACTION_ORDER' statement contains the ordinal position of the
     trigger's action within the list of all similar triggers on the
     same table. Currently, this value is always `0', because it is not
     possible to have more than one trigger with the same
     `EVENT_MANIPULATION' and `ACTION_TIMING' on the same table.

   * The `ACTION_STATEMENT' column contains the statement to be
     executed when the trigger is invoked. This is the same as the text
     displayed in the `Statement' column of the output from *Note `SHOW
     TRIGGERS': show-triggers. Note that this text uses UTF-8 encoding.

   * The `ACTION_ORIENTATION' column always contains the value `'ROW''.

   * The `ACTION_TIMING' column contains one of the two values
     `'BEFORE'' or `'AFTER''.

   * The columns `ACTION_REFERENCE_OLD_ROW' and
     `ACTION_REFERENCE_NEW_ROW' contain the old and new column
     identifiers, respectively. This means that
     `ACTION_REFERENCE_OLD_ROW' always contains the value `'OLD'' and
     `ACTION_REFERENCE_NEW_ROW' always contains the value `'NEW''.

   * The `SQL_MODE' column shows the server SQL mode that was in effect
     at the time when the trigger was created (and thus which remains
     in effect for this trigger whenever it is invoked, _regardless of
     the current server SQL mode_). The possible range of values for
     this column is the same as that of the `sql_mode' system variable.
     See *Note server-sql-mode::.

   * The `DEFINER' column indicates who defined the trigger.

   * `CHARACTER_SET_CLIENT' is the session value of the
     `character_set_client' system variable when the trigger was
     created.  `COLLATION_CONNECTION' is the session value of the
     `collation_connection' system variable when the trigger was
     created.  `DATABASE_COLLATION' is the collation of the database
     with which the trigger is associated.

   * The following columns currently always contain `NULL':
     `ACTION_CONDITION', `ACTION_REFERENCE_OLD_TABLE',
     `ACTION_REFERENCE_NEW_TABLE', and `CREATED'.

Example, using the `ins_sum' trigger defined in *Note triggers:::

     mysql> SELECT * FROM INFORMATION_SCHEMA.TRIGGERS\G
     *************************** 1. row ***************************
                TRIGGER_CATALOG: def
                 TRIGGER_SCHEMA: test
                   TRIGGER_NAME: ins_sum
             EVENT_MANIPULATION: INSERT
           EVENT_OBJECT_CATALOG: def
            EVENT_OBJECT_SCHEMA: test
             EVENT_OBJECT_TABLE: account
                   ACTION_ORDER: 0
               ACTION_CONDITION: NULL
               ACTION_STATEMENT: SET @sum = @sum + NEW.amount
             ACTION_ORIENTATION: ROW
                  ACTION_TIMING: BEFORE
     ACTION_REFERENCE_OLD_TABLE: NULL
     ACTION_REFERENCE_NEW_TABLE: NULL
       ACTION_REFERENCE_OLD_ROW: OLD
       ACTION_REFERENCE_NEW_ROW: NEW
                        CREATED: NULL
                       SQL_MODE:
                        DEFINER: me@localhost

See also *Note show-triggers::.


File: manual.info,  Node: plugins-table,  Next: engines-table,  Prev: triggers-table,  Up: information-schema

19.17 The `INFORMATION_SCHEMA PLUGINS' Table
============================================

The *Note `PLUGINS': plugins-table. table provides information about
server plugins.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`PLUGIN_NAME'                 `Name'                 MySQL extension
`PLUGIN_VERSION'                                     MySQL extension
`PLUGIN_STATUS'               `Status'               MySQL extension
`PLUGIN_TYPE'                 `Type'                 MySQL extension
`PLUGIN_TYPE_VERSION'                                MySQL extension
`PLUGIN_LIBRARY'              `Library'              MySQL extension
`PLUGIN_LIBRARY_VERSION'                             MySQL extension
`PLUGIN_AUTHOR'                                      MySQL extension
`PLUGIN_DESCRIPTION'                                 MySQL extension
`PLUGIN_LICENSE'                                     MySQL extension

*Notes*:

   * The *Note `PLUGINS': plugins-table. table is a non-standard table.

See also *Note show-plugins::.


File: manual.info,  Node: engines-table,  Next: partitions-table,  Prev: plugins-table,  Up: information-schema

19.18 The `INFORMATION_SCHEMA ENGINES' Table
============================================

The *Note `PLUGINS': plugins-table. table provides information about
storage engines.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`ENGINE'                      `Engine'               MySQL extension
`SUPPORT'                     `Support'              MySQL extension
`COMMENT'                     `Comment'              MySQL extension
`TRANSACTIONS'                `Transactions'         MySQL extension
`XA'                          `XA'                   MySQL extension
`SAVEPOINTS'                  `Savepoints'           MySQL extension

*Notes*:

   * The *Note `ENGINES': engines-table. table is a non-standard table.

See also *Note show-engines::.


File: manual.info,  Node: partitions-table,  Next: events-table,  Prev: engines-table,  Up: information-schema

19.19 The `INFORMATION_SCHEMA PARTITIONS' Table
===============================================

The *Note `PARTITIONS': partitions-table. table provides information
about table partitions. See *Note partitioning::, for more information
about partitioning tables.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`TABLE_CATALOG'                                      MySQL extension
`TABLE_SCHEMA'                                       MySQL extension
`TABLE_NAME'                                         MySQL extension
`PARTITION_NAME'                                     MySQL extension
`SUBPARTITION_NAME'                                  MySQL extension
`PARTITION_ORDINAL_POSITION'                         MySQL extension
`SUBPARTITION_ORDINAL_POSITION'                       MySQL extension
`PARTITION_METHOD'                                   MySQL extension
`SUBPARTITION_METHOD'                                MySQL extension
`PARTITION_EXPRESSION'                               MySQL extension
`SUBPARTITION_EXPRESSION'                            MySQL extension
`PARTITION_DESCRIPTION'                              MySQL extension
`TABLE_ROWS'                                         MySQL extension
`AVG_ROW_LENGTH'                                     MySQL extension
`DATA_LENGTH'                                        MySQL extension
`MAX_DATA_LENGTH'                                    MySQL extension
`INDEX_LENGTH'                                       MySQL extension
`DATA_FREE'                                          MySQL extension
`CREATE_TIME'                                        MySQL extension
`UPDATE_TIME'                                        MySQL extension
`CHECK_TIME'                                         MySQL extension
`CHECKSUM'                                           MySQL extension
`PARTITION_COMMENT'                                  MySQL extension
`NODEGROUP'                                          MySQL extension
`TABLESPACE_NAME'                                    MySQL extension

*Notes*:

   * The *Note `PARTITIONS': partitions-table. table is a non-standard
     table.

     Each record in this table corresponds to an individual partition
     or subpartition of a partitioned table.

   * `TABLE_CATALOG': This column is always `def'.

   * `TABLE_SCHEMA': This column contains the name of the database to
     which the table belongs.

   * `TABLE_NAME': This column contains the name of the table
     containing the partition.

   * `PARTITION_NAME': The name of the partition.

   * `SUBPARTITION_NAME': If the *Note `PARTITIONS': partitions-table.
     table record represents a subpartition, then this column contains
     the name of subpartition; otherwise it is `NULL'.

   * `PARTITION_ORDINAL_POSITION': All partitions are indexed in the
     same order as they are defined, with `1' being the number assigned
     to the first partition. The indexing can change as partitions are
     added, dropped, and reorganized; the number shown is this column
     reflects the current order, taking into account any indexing
     changes.

   * `SUBPARTITION_ORDINAL_POSITION': Subpartitions within a given
     partition are also indexed and reindexed in the same manner as
     partitions are indexed within a table.

   * `PARTITION_METHOD': One of the values `RANGE', `LIST', `HASH',
     `LINEAR HASH', `KEY', or `LINEAR KEY'; that is, one of the
     available partitioning types as discussed in *Note
     partitioning-types::.

   * `SUBPARTITION_METHOD': One of the values `HASH', `LINEAR HASH',
     `KEY', or `LINEAR KEY'; that is, one of the available
     subpartitioning types as discussed in *Note
     partitioning-subpartitions::.

   * `PARTITION_EXPRESSION': This is the expression for the
     partitioning function used in the *Note `CREATE TABLE':
     create-table. or *Note `ALTER TABLE': alter-table. statement that
     created the table's current partitioning scheme.

     For example, consider a partitioned table created in the `test'
     database using this statement:

          CREATE TABLE tp (
              c1 INT,
              c2 INT,
              c3 VARCHAR(25)
          )
          PARTITION BY HASH(c1 + c2)
          PARTITIONS 4;

     The `PARTITION_EXPRESSION' column in a PARTITIONS table record for
     a partition from this table displays `c1 + c2', as shown here:

          mysql> SELECT DISTINCT PARTITION_EXPRESSION
               >     FROM INFORMATION_SCHEMA.PARTITIONS
               >     WHERE TABLE_NAME='tp' AND TABLE_SCHEMA='test';
          +----------------------+
          | PARTITION_EXPRESSION |
          +----------------------+
          | c1 + c2              |
          +----------------------+
          1 row in set (0.09 sec)

   * `SUBPARTITION_EXPRESSION': This works in the same fashion for the
     subpartitioning expression that defines the subpartitioning for a
     table as `PARTITION_EXPRESSION' does for the partitioning
     expression used to define a table's partitioning.

     If the table has no subpartitions, then this column is `NULL'.

   * `PARTITION_DESCRIPTION': This column is used for RANGE and LIST
     partitions. For a `RANGE' partition, it contains the value set in
     the partition's `VALUES LESS THAN' clause, which can be either an
     integer or `MAXVALUE'. For a `LIST' partition, this column
     contains the values defined in the partition's `VALUES IN' clause,
     which is a comma-separated list of integer values.

     For partitions whose `PARTITION_METHOD' is other than `RANGE' or
     `LIST', this column is always `NULL'.

   * `TABLE_ROWS': The number of table rows in the partition.

   * `AVG_ROW_LENGTH': The average length of the rows stored in this
     partition or subpartition, in bytes.

     This is the same as `DATA_LENGTH' divided by `TABLE_ROWS'.

   * `DATA_LENGTH': The total length of all rows stored in this
     partition or subpartition, in bytes -- that is, the total number
     of bytes stored in the partition or subpartition.

   * `MAX_DATA_LENGTH': The maximum number of bytes that can be stored
     in this partition or subpartition.

   * `INDEX_LENGTH': The length of the index file for this partition or
     subpartition, in bytes.

   * `DATA_FREE': The number of bytes allocated to the partition or
     subpartition but not used.

   * `CREATE_TIME': The time of the partition's or subpartition's
     creation.

   * `UPDATE_TIME': The time that the partition or subpartition was
     last modified.

   * `CHECK_TIME': The last time that the table to which this partition
     or subpartition belongs was checked.

     *Note*:

     Some storage engines do not update this time; for tables using
     these storage engines, this value is always `NULL'.

   * `CHECKSUM': The checksum value, if any; otherwise, this column is
     `NULL'.

   * `PARTITION_COMMENT': This column contains the text of any comment
     made for the partition.

     The default value for this column is an empty string.

   * `NODEGROUP': This is the nodegroup to which the partition belongs.
     This is relevant only to MySQL Cluster tables; otherwise the value
     of this column is always `0'.

     *Note*:

     The `NDBCLUSTER' storage engine is currently not supported in
     MySQL 6.0. If you are interested in using MySQL Cluster, see MySQL
     Cluster NDB 6.X/7.X
     (http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html), which
     provides information about MySQL Cluster NDB 6.2 and 6.3 (based on
     MySQL 5.1 but containing the latest improvements and fixes for
     `NDBCLUSTER').

   * `TABLESPACE_NAME': This column contains the name of tablespace to
     which the partition belongs. In MySQL 6.0, the value of this
     column is always `DEFAULT'.

   * A non-partitioned table has one record in *Note
     `INFORMATION_SCHEMA.PARTITIONS': partitions-table.; however, the
     values of the `PARTITION_NAME', `SUBPARTITION_NAME',
     `PARTITION_ORDINAL_POSITION', `SUBPARTITION_ORDINAL_POSITION',
     `PARTITION_METHOD', `SUBPARTITION_METHOD', `PARTITION_EXPRESSION',
     `SUBPARTITION_EXPRESSION', and `PARTITION_DESCRIPTION' columns are
     all `NULL'. (The `PARTITION_COMMENT' column in this case is blank.)


File: manual.info,  Node: events-table,  Next: files-table,  Prev: partitions-table,  Up: information-schema

19.20 The `INFORMATION_SCHEMA EVENTS' Table
===========================================

The *Note `EVENTS': events-table. table provides information about
scheduled events, which are discussed in *Note events::.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`EVENT_CATALOG'                                      `def', MySQL extension
`EVENT_SCHEMA'                `Db'                   MySQL extension
`EVENT_NAME'                  `Name'                 MySQL extension
`DEFINER'                     `Definer'              MySQL extension
`TIME_ZONE'                   `Time zone'            MySQL extension
`EVENT_BODY'                                         MySQL extension
`EVENT_DEFINITION'                                   MySQL extension
`EVENT_TYPE'                  `Type'                 MySQL extension
`EXECUTE_AT'                  `Execute at'           MySQL extension
`INTERVAL_VALUE'              `Interval value'       MySQL extension
`INTERVAL_FIELD'              `Interval field'       MySQL extension
`SQL_MODE'                                           MySQL extension
`STARTS'                      `Starts'               MySQL extension
`ENDS'                        `Ends'                 MySQL extension
`STATUS'                      `Status'               MySQL extension
`ON_COMPLETION'                                      MySQL extension
`CREATED'                                            MySQL extension
`LAST_ALTERED'                                       MySQL extension
`LAST_EXECUTED'                                      MySQL extension
`EVENT_COMMENT'                                      MySQL extension
`ORIGINATOR'                  Originator             MySQL extension
`CHARACTER_SET_CLIENT'                               MySQL extension
`COLLATION_CONNECTION'                               MySQL extension
`DATABASE_COLLATION'                                 MySQL extension

*Notes*:

   * The *Note `EVENTS': events-table. table is a non-standard table.

   * `EVENT_CATALOG': The value of this column is always `def'.

   * `EVENT_SCHEMA': The name of the schema (database) to which this
     event belongs.

   * `EVENT_NAME': The name of the event.

   * `DEFINER': The user who created the event.  Always displayed in
     `'USER_NAME'@'HOST_NAME'' format.

   * `TIME_ZONE': The time zone in effect when schedule for the event
     was last modified. If the event's schedule has not been modified
     since the event was created, then this is the time zone that was
     in effect at the event's creation. The default value is `SYSTEM'.

   * `EVENT_BODY': The language used for the statements in the event's
     *Note `DO': do.  clause; in MySQL 6.0, this is always `SQL'.

     This column is not to be confused with the column of the same name
     (now named `EVENT_DEFINITION') that existed in earlier MySQL
     versions.

   * `EVENT_DEFINITION': The text of the SQL statement making up the
     event's *Note `DO': do. clause; in other words, the statement
     executed by this event.

   * `EVENT_TYPE': One of the two values `ONE TIME' or `RECURRING'.

   * `EXECUTE_AT': For a one-time event, this is the *Note `DATETIME':
     datetime. value specified in the `AT' clause of the *Note `CREATE
     EVENT': create-event. statement used to create the event, or of
     the last *Note `ALTER EVENT': alter-event. statement that modified
     the event. The value shown in this column reflects the addition or
     subtraction of any `INTERVAL' value included in the event's `AT'
     clause. For example, if an event is created using `ON SCHEDULE AT
     CURRENT_TIMESTAMP + '1:6' DAY_HOUR', and the event was created at
     2006-02-09 14:05:30, the value shown in this column would be
     `'2006-02-10 20:05:30''.

     If the event's timing is determined by an `EVERY' clause instead
     of an `AT' clause (that is, if the event is recurring), the value
     of this column is `NULL'.

   * `INTERVAL_VALUE': For recurring events, this column contains the
     numeric portion of the event's `EVERY' clause.

     For a one-time event (that is, an event whose timing is determined
     by an `AT' clause), this column's value is `NULL'.

   * `INTERVAL_FIELD': For recurring events, this column contains the
     units portion of the `EVERY' clause governing the timing of the
     event. Thus, this column contains a value such as '*Note `YEAR':
     year.', '`QUARTER'', '`DAY'', and so on.

     For a one-time event (that is, an event whose timing is determined
     by an `AT' clause), this column's value is `NULL'.

   * `SQL_MODE': The SQL mode in effect at the time the event was
     created or altered.

   * `STARTS': For a recurring event whose definition includes a
     `STARTS' clause, this column contains the corresponding *Note
     `DATETIME': datetime. value. As with the `EXECUTE_AT' column, this
     value resolves any expressions used.

     If there is no `STARTS' clause affecting the timing of the event,
     this column is empty.

   * `ENDS': For a recurring event whose definition includes a `ENDS'
     clause, this column contains the corresponding *Note `DATETIME':
     datetime. value. As with the `EXECUTE_AT' column (see previous
     example), this value resolves any expressions used.

     If there is no `ENDS' clause affecting the timing of the event,
     this column contains `NULL'.

   * `STATUS': One of the three values `ENABLED', `DISABLED', or
     `SLAVESIDE_DISABLED'.

     `SLAVESIDE_DISABLED' indicates that the creation of the event
     occurred on another MySQL server acting as a replication master
     and was replicated to the current MySQL server which is acting as
     a slave, but the event is not presently being executed on the
     slave. See *Note replication-features-invoked::, for more
     information.

   * `ON_COMPLETION': One of the two values `PRESERVE' or `NOT
     PRESERVE'.

   * `CREATED': The date and time when the event was created. This is a
     *Note `DATETIME': datetime.  value.

   * `LAST_ALTERED': The date and time when the event was last
     modified. This is a *Note `DATETIME': datetime. value. If the event
     has not been modified since its creation, this column holds the
     same value as the `CREATED' column.

   * `LAST_EXECUTED': The date and time when the event last executed. A
     *Note `DATETIME': datetime.  value. If the event has never
     executed, this column's value is `NULL'.

     Before MySQL 6.0.5, `LAST_EXECUTED' indicates when event finished
     executing. As of 6.0.5, `LAST_EXECUTED' instead indicates when the
     event started. As a result, the `ENDS' column is never less than
     `LAST_EXECUTED'.

   * `EVENT_COMMENT': The text of a comment, if the event has one. If
     there is no comment, the value of this column is an empty string.

   * `ORIGINATOR': The server ID of the MySQL server on which the event
     was created; used in replication.  The default value is 0.

   * `CHARACTER_SET_CLIENT' is the session value of the
     `character_set_client' system variable when the event was created.
     `COLLATION_CONNECTION' is the session value of the
     `collation_connection' system variable when the event was created.
     `DATABASE_COLLATION' is the collation of the database with which
     the event is associated.

*Example*: Suppose the user `jon@ghidora' creates an event named
`e_daily', and then modifies it a few minutes later using an *Note
`ALTER EVENT': alter-event.  statement, as shown here:

     DELIMITER |

     CREATE EVENT e_daily
         ON SCHEDULE
           EVERY 1 DAY
         COMMENT 'Saves total number of sessions then clears the table each day'
         DO
           BEGIN
             INSERT INTO site_activity.totals (time, total)
               SELECT CURRENT_TIMESTAMP, COUNT(*)
                 FROM site_activity.sessions;
             DELETE FROM site_activity.sessions;
           END |

     DELIMITER ;

     ALTER EVENT e_daily
         ENABLED;

(Note that comments can span multiple lines.)

This user can then run the following *Note `SELECT': select. statement,
and obtain the output shown:

     mysql> SELECT * FROM INFORMATION_SCHEMA.EVENTS
          > WHERE EVENT_NAME = 'e_daily'
          > AND EVENT_SCHEMA = 'myschema'\G
     *************************** 1. row ***************************
            EVENT_CATALOG: def
             EVENT_SCHEMA: test
               EVENT_NAME: e_daily
                  DEFINER: paul@localhost
                TIME_ZONE: SYSTEM
               EVENT_BODY: SQL
         EVENT_DEFINITION: BEGIN
             INSERT INTO site_activity.totals (time, total)
               SELECT CURRENT_TIMESTAMP, COUNT(*)
                 FROM site_activity.sessions;
             DELETE FROM site_activity.sessions;
           END
               EVENT_TYPE: RECURRING
               EXECUTE_AT: NULL
           INTERVAL_VALUE: 1
           INTERVAL_FIELD: DAY
                 SQL_MODE:
                   STARTS: 2008-09-03 12:13:39
                     ENDS: NULL
                   STATUS: ENABLED
            ON_COMPLETION: NOT PRESERVE
                  CREATED: 2008-09-03 12:13:39
             LAST_ALTERED: 2008-09-03 12:13:39
            LAST_EXECUTED: NULL
            EVENT_COMMENT: Saves total number of sessions then clears the
                           table each day
               ORIGINATOR: 1
     CHARACTER_SET_CLIENT: latin1
     COLLATION_CONNECTION: latin1_swedish_ci
       DATABASE_COLLATION: latin1_swedish_ci

These times are all given in terms of local time as determined by the
MySQL server's `time_zone' setting. (The same is true of the `starts',
`ends', and `last_executed' columns of the `mysql.event' table as well
as the `Starts' and `Ends' columns in the output of `SHOW [FULL]
EVENTS'.)

The `CREATED' and `LAST_ALTERED' columns use the server time zone (as
do the `created' and `last_altered' columns of the `mysql.event' table).

See also *Note show-events::.


File: manual.info,  Node: files-table,  Next: tablespaces-table,  Prev: events-table,  Up: information-schema

19.21 The `INFORMATION_SCHEMA FILES' Table
==========================================

The *Note `FILES': files-table. table provides information about the
files in which MySQL `Falcon' tablespace data is stored. The table was
added in MySQL 6.0.8.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`FILE_ID'                                            MySQL extension
`FILE_NAME'                                          MySQL extension
`FILE_TYPE'                                          MySQL extension
`TABLESPACE_NAME'                                    MySQL extension
`TABLE_CATALOG'                                      MySQL extension
`TABLE_SCHEMA'                                       MySQL extension
`TABLE_NAME'                                         MySQL extension
`LOGFILE_GROUP_NAME'                                 MySQL extension
`LOGFILE_GROUP_NUMBER'                               MySQL extension
`ENGINE'                                             MySQL extension
`FULLTEXT_KEYS'                                      MySQL extension
`DELETED_ROWS'                                       MySQL extension
`UPDATE_COUNT'                                       MySQL extension
`FREE_EXTENTS'                                       MySQL extension
`TOTAL_EXTENTS'                                      MySQL extension
`EXTENT_SIZE'                                        MySQL extension
`INITIAL_SIZE'                                       MySQL extension
`MAXIMUM_SIZE'                                       MySQL extension
`AUTOEXTEND_SIZE'                                    MySQL extension
`CREATION_TIME'                                      MySQL extension
`LAST_UPDATE_TIME'                                   MySQL extension
`LAST_ACCESS_TIME'                                   MySQL extension
`RECOVER_TIME'                                       MySQL extension
`TRANSACTION_COUNTER'                                MySQL extension
`VERSION'                                            MySQL extension
`ROW_FORMAT'                                         MySQL extension
`TABLE_ROWS'                                         MySQL extension
`AVG_ROW_LENGTH'                                     MySQL extension
`DATA_LENGTH'                                        MySQL extension
`MAX_DATA_LENGTH'                                    MySQL extension
`INDEX_LENGTH'                                       MySQL extension
`DATA_FREE'                                          MySQL extension
`CREATE_TIME'                                        MySQL extension
`UPDATE_TIME'                                        MySQL extension
`CHECK_TIME'                                         MySQL extension
`CHECKSUM'                                           MySQL extension
`STATUS'                                             MySQL extension
`EXTRA'                                              MySQL extension

*Notes*:

   * `FILE_ID' column values are auto-generated.

   * `FILE_NAME' is the name of a data file created by `CREATE
     TABLESPACE' or `ALTER TABLESPACE'.

   * `FILE_TYPE' is `SYSTEM DATAFILE' for the `FALCON_MASTER',
     `FALCON_USER' and `FALCON_TEMPORARY' tablespace files, or `USER
     DATAFILE' for any user-create tablespace files.

   * `TABLESPACE_NAME' is the name of the tablespace with which the
     file is associated.

   * Currently, the value of the `TABLESPACE_CATALOG' column is always
     `NULL'.

   * `TABLE_NAME' is the name of the table with which the file is
     associated, if any.

   * The `EXTENT_SIZE' is always `0'.

   * For MySQL `Falcon' tablespace files, the following columns are
     always `NULL':

        * `TABLESPACE_CATALOG'

        * ` TABLE_SCHEMA'

        * ` TABLE_NAME'

        * ` LOGFILE_GROUP_NAME'

        * ` LOGFILE_GROUP_NUMBER'

        * ` FULLTEXT_KEYS'

        * ` DELETED_ROWS'

        * ` UPDATE_COUNT'

        * ` FREE_EXTENTS'

        * ` TOTAL_EXTENTS'

        * ` INITIAL_SIZE'

        * ` MAXIMUM_SIZE'

        * ` AUTOEXTEND_SIZE'

        * ` CREATION_TIME'

        * ` LAST_UPDATE_TIME'

        * ` LAST_ACCESS_TIME'

        * ` RECOVER_TIME'

        * ` TRANSACTION_COUNTER'

        * `VERSION'

        * `ROW_FORMAT'

        * `TABLE_ROWS'

        * `AVG_ROW_LENGTH'

        * `DATA_LENGTH'

        * `MAX_DATA_LENGTH'

        * `INDEX_LENGTH'

        * `DATA_FREE'

        * `CREATE_TIME'

        * `UPDATE_TIME'

        * `CHECK_TIME'

        * `CHECKSUM'

   * For `Falcon' tablespaces, the value of the `STATUS' column is
     always `NORMAL'.

   * There are no *Note `SHOW': show. commands associated with the
     *Note `FILES': files-table. table.


File: manual.info,  Node: tablespaces-table,  Next: processlist-table,  Prev: files-table,  Up: information-schema

19.22 The `INFORMATION_SCHEMA TABLESPACES' Table
================================================

The *Note `TABLESPACES': tablespaces-table. table provides information
about active tablespaces. The table was added in MySQL 6.0.8.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`TABLESPACE_NAME'                                    MySQL extension
`ENGINE'                                             MySQL extension
`TABLESPACE_TYPE'                                    MySQL extension
`LOGFILE_GROUP_NAME'                                 MySQL extension
`EXTENT_SIZE'                                        MySQL extension
`AUTOEXTEND_SIZE'                                    MySQL extension
`MAXIMUM_SIZE'                                       MySQL extension
`NODEGROUP_ID'                                       MySQL extension
`TABLESPACE_COMMENT'                                 MySQL extension

*Notes*:

   * The `TABLESPACE_NAME' will be filled with the name of the `Falcon'
     tablespace.

   * The `Engine' will be set to `Falcon'.

   * The `TABLESPACE_TYPE' will be set tp `DEFAULT' for the default
     tablespace used by `Falcon'; to `TEMPORARY' for temporary `Falcon'
     tables; to `MASTER CATALOG' for the internal `Falcon' files and
     `USER DEFINED' for all user tablespaces

   * The following fields will be set to `NULL' for `Falcon' tables:

        * `LOGFILE_GROUP_NAME'

        * `EXTENT_SIZE'

        * `AUTOEXTEND_SIZE'

        * `MAXIMUM_SIZE'

        * `NODEGROUP_ID'

        * `TABLESPACE_COMMENT'


File: manual.info,  Node: processlist-table,  Next: referential-constraints-table,  Prev: tablespaces-table,  Up: information-schema

19.23 The `INFORMATION_SCHEMA PROCESSLIST' Table
================================================

The *Note `PROCESSLIST': processlist-table. table provides information
about which threads are running.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`ID'                          `Id'                   MySQL extension
`USER'                        `User'                 MySQL extension
`HOST'                        `Host'                 MySQL extension
`DB'                          `db'                   MySQL extension
`COMMAND'                     `Command'              MySQL extension
*Note `TIME': time.           `Time'                 MySQL extension
`STATE'                       `State'                MySQL extension
`INFO'                        `Info'                 MySQL extension

For an extensive description of the table columns, see *Note
show-processlist::.

*Notes*:

   * The *Note `PROCESSLIST': processlist-table. table is a
     non-standard table.

   * Like the output from the corresponding *Note `SHOW': show.
     statement, the *Note `PROCESSLIST': processlist-table. table will
     only show information about your own threads, unless you have the
     `PROCESS' privilege, in which case you will see information about
     other threads, too. As an anonymous user, you cannot see any rows
     at all.

   * If an SQL statement refers to *Note
     `INFORMATION_SCHEMA.PROCESSLIST': processlist-table, then MySQL
     will populate the entire table once, when statement execution
     begins, so there is read consistency during the statement. There
     is no read consistency for a multi-statement transaction, though.

The following statements are equivalent:

     SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST

     SHOW FULL PROCESSLIST


File: manual.info,  Node: referential-constraints-table,  Next: status-table,  Prev: processlist-table,  Up: information-schema

19.24 The `INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS' Table
============================================================

The *Note `REFERENTIAL_CONSTRAINTS': referential-constraints-table.
table provides information about foreign keys.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
CONSTRAINT_CATALOG                                   def
CONSTRAINT_SCHEMA                                    
CONSTRAINT_NAME                                      
UNIQUE_CONSTRAINT_CATALOG                            def
UNIQUE_CONSTRAINT_SCHEMA                             
UNIQUE_CONSTRAINT_NAME                               
MATCH_OPTION                                         
UPDATE_RULE                                          
DELETE_RULE                                          
TABLE_NAME                                           
REFERENCED_TABLE_NAME                                

*Notes*:

   * `TABLE_NAME' has the same value as `TABLE_NAME' in *Note
     `INFORMATION_SCHEMA.TABLE_CONSTRAINTS': table-constraints-table.

   * `CONSTRAINT_SCHEMA' and `CONSTRAINT_NAME' identify the foreign key.

   * `UNIQUE_CONSTRAINT_SCHEMA', `UNIQUE_CONSTRAINT_NAME', and
     `REFERENCED_TABLE_NAME' identify the referenced key.

   * The only valid value at this time for `MATCH_OPTION' is `NONE'.

   * The possible values for `UPDATE_RULE' or `DELETE_RULE' are
     `CASCADE', `SET NULL', `SET DEFAULT', `RESTRICT', `NO ACTION'.


File: manual.info,  Node: status-table,  Next: variables-table,  Prev: referential-constraints-table,  Up: information-schema

19.25 The `INFORMATION_SCHEMA GLOBAL_STATUS' and `SESSION_STATUS' Tables
========================================================================

The *Note `GLOBAL_STATUS': status-table.  and *Note `SESSION_STATUS':
status-table.  tables provide information about server status
variables. Their contents correspond to the information produced by the
*Note `SHOW GLOBAL STATUS': show-status. and *Note `SHOW SESSION
STATUS': show-status. statements (see *Note show-status::).

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
VARIABLE_NAME                 Variable_name          
VARIABLE_VALUE                Value                  

*Notes*:

   * The `VARIABLE_VALUE' column for each of these tables is defined as
     `VARCHAR(20480)'.


File: manual.info,  Node: variables-table,  Next: parameters-table,  Prev: status-table,  Up: information-schema

19.26 The `INFORMATION_SCHEMA GLOBAL_VARIABLES' and `SESSION_VARIABLES' Tables
==============================================================================

The *Note `GLOBAL_VARIABLES': variables-table.  and *Note
`SESSION_VARIABLES': variables-table.  tables provide information about
server status variables. Their contents correspond to the information
produced by the *Note `SHOW GLOBAL VARIABLES': show-variables. and
*Note `SHOW SESSION VARIABLES': show-variables. statements (see *Note
show-variables::).

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
VARIABLE_NAME                 Variable_name          
VARIABLE_VALUE                Value                  

*Notes*:

   * The `VARIABLE_VALUE' column for each of these tables is defined as
     `VARCHAR(20480)'.


File: manual.info,  Node: parameters-table,  Next: profiling-table,  Prev: variables-table,  Up: information-schema

19.27 The `INFORMATION_SCHEMA PARAMETERS' Table
===============================================

The *Note `PARAMETERS': parameters-table. table provides information
about stored function and procedure parameters, and about return values
for stored functions. Parameter information is similar to the contents
of the `param_list' column in the `mysql.proc' table.

*`INFORMATION_SCHEMA' Name*   *`mysql.proc' Name*    *Remarks*
`SPECIFIC_CATALOG'                                   `def'
`SPECIFIC_SCHEMA'             `db'                   routine database
`SPECIFIC_NAME'               `name'                 routine name
`ORDINAL_POSITION'                                   1, 2, 3, ... for
                                                     parameters, 0 for
                                                     function `RETURNS'
                                                     clause
`PARAMETER_MODE'                                     `IN', `OUT', `INOUT'
                                                     (`NULL' for `RETURNS')
`PARAMETER_NAME'                                     parameter name
                                                     (`NULL' for `RETURNS')
`DATA_TYPE'                                          same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`CHARACTER_MAXIMUM_LENGTH'                           same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`CHARACTER_OCTET_LENGTH'                             same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`NUMERIC_PRECISION'                                  same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`NUMERIC_SCALE'                                      same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`CHARACTER_SET_NAME'                                 same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`COLLATION_NAME'                                     same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`DTD_IDENTIFIER'                                     same as for *Note
                                                     `COLUMNS':
                                                     columns-table. table
`ROUTINE_TYPE'                type                   same as for *Note
                                                     `ROUTINES':
                                                     routines-table. table

*Notes*:

   * The *Note `PARAMETERS': parameters-table. table was added in MySQL
     5.2.6.

   * For successive parameters of a stored function or procedure, the
     `ORDINAL_POSITION' values are 1, 2, 3, and so forth. For a stored
     function, there is also a row that describes the data type for the
     `RETURNS' clause. The return value is not a true parameter, so the
     row that describes it has these unique characteristics:

        * The `ORDINAL_POSITION' value is 0.

        * The `PARAMETER_NAME' and `PARAMETER_MODE' values are `NULL'
          because the return value has no name and the mode does not
          apply.

   * The `ROUTINE_TYPE' column was added in MySQL 6.0.5. (Bug#33106
     (http://bugs.mysql.com/33106))


File: manual.info,  Node: profiling-table,  Next: other-information-schema-tables,  Prev: parameters-table,  Up: information-schema

19.28 The `INFORMATION_SCHEMA PROFILING' Table
==============================================

The *Note `PROFILING': profiling-table. table provides statement
profiling information. Its contents correspond to the information
produced by the *Note `SHOW PROFILES': show-profiles. and *Note `SHOW
PROFILE': show-profile.  statements (see *Note show-profiles::). The
table is empty unless the `profiling' session variable is set to 1.

*`INFORMATION_SCHEMA' Name*   **Note `SHOW': show.   *Remarks*
                              Name*                  
`QUERY_ID'                    `Query_ID'             
`SEQ'                         `'                     
`STATE'                       `Status'               
`DURATION'                    `Duration'             
`CPU_USER'                    `CPU_user'             
`CPU_SYSTEM'                  `CPU_system'           
`CONTEXT_VOLUNTARY'           `Context_voluntary'    
`CONTEXT_INVOLUNTARY'         `Context_involuntary'  
`BLOCK_OPS_IN'                `Block_ops_in'         
`BLOCK_OPS_OUT'               `Block_ops_out'        
`MESSAGES_SENT'               `Messages_sent'        
`MESSAGES_RECEIVED'           `Messages_received'    
`PAGE_FAULTS_MAJOR'           `Page_faults_major'    
`PAGE_FAULTS_MINOR'           `Page_faults_minor'    
`SWAPS'                       `Swaps'                
`SOURCE_FUNCTION'             `Source_function'      
`SOURCE_FILE'                 `Source_file'          
`SOURCE_LINE'                 `Source_line'          

*Notes*:

   * The *Note `PROFILING': profiling-table. table was added in MySQL
     6.0.5.

   * `QUERY_ID' is a numeric statement identifier.

   * `SEQ' is a sequence number indicating the display order for rows
     with the same `QUERY_ID' value.

   * `STATE' is the profiling state to which the row measurements apply.

   * `DURATION' indicates how long statement execution remained in the
     given state, in seconds.

   * `CPU_USER' and `CPU_SYSTEM' indicate user and system CPU use, in
     seconds.

   * `CONTEXT_VOLUNTARY' and `CONTEXT_INVOLUNTARY' indicate how many
     voluntary and involuntary context switches occurred.

   * `BLOCK_OPS_IN' and `BLOCK_OPS_OUT' indicate the number of block
     input and output operations.

   * `MESSAGES_SENT' and `MESSAGES_RECEIVED' indicate the number of
     communication messages sent and received.

   * `PAGE_FAULTS_MAJOR' and `PAGE_FAULTS_MINOR' indicate the number of
     major and minor page faults.

   * `SWAPS' indicates how many swaps occurred.

   * `SOURCE_FUNCTION', `SOURCE_FILE', and `SOURCE_LINE' provide
     information indicating where in the source code the profiled state
     executes.


File: manual.info,  Node: other-information-schema-tables,  Next: extended-show,  Prev: profiling-table,  Up: information-schema

19.29 Other `INFORMATION_SCHEMA' Tables
=======================================

We intend to implement additional `INFORMATION_SCHEMA' tables.


File: manual.info,  Node: extended-show,  Prev: other-information-schema-tables,  Up: information-schema

19.30 Extensions to `SHOW' Statements
=====================================

Some extensions to *Note `SHOW': show. statements accompany the
implementation of `INFORMATION_SCHEMA':

   * *Note `SHOW': show. can be used to get information about the
     structure of `INFORMATION_SCHEMA' itself.

   * Several *Note `SHOW': show. statements accept a `WHERE' clause
     that provides more flexibility in specifying which rows to display.

`INFORMATION_SCHEMA' is an information database, so its name is
included in the output from *Note `SHOW DATABASES': show-databases.
Similarly, *Note `SHOW TABLES': show-tables. can be used with
`INFORMATION_SCHEMA' to obtain a list of its tables:

     mysql> SHOW TABLES FROM INFORMATION_SCHEMA;
     +---------------------------------------+
     | Tables_in_INFORMATION_SCHEMA          |
     +---------------------------------------+
     | CHARACTER_SETS                        |
     | COLLATIONS                            |
     | COLLATION_CHARACTER_SET_APPLICABILITY |
     | COLUMNS                               |
     | COLUMN_PRIVILEGES                     |
     | ENGINES                               |
     | EVENTS                                |
     | FILES                                 |
     | GLOBAL_STATUS                         |
     | GLOBAL_VARIABLES                      |
     | KEY_COLUMN_USAGE                      |
     | PARTITIONS                            |
     | PLUGINS                               |
     | PROCESSLIST                           |
     | REFERENTIAL_CONSTRAINTS               |
     | ROUTINES                              |
     | SCHEMATA                              |
     | SCHEMA_PRIVILEGES                     |
     | SESSION_STATUS                        |
     | SESSION_VARIABLES                     |
     | STATISTICS                            |
     | TABLES                                |
     | TABLE_CONSTRAINTS                     |
     | TABLE_PRIVILEGES                      |
     | TRIGGERS                              |
     | USER_PRIVILEGES                       |
     | VIEWS                                 |
     +---------------------------------------+
     27 rows in set (0.00 sec)

*Note `SHOW COLUMNS': show-columns. and *Note `DESCRIBE': describe. can
display information about the columns in individual
`INFORMATION_SCHEMA' tables.

*Note `SHOW': show. statements that accept a `LIKE' clause to limit the
rows displayed also allow a `WHERE' clause that enables specification
of more general conditions that selected rows must satisfy:

     SHOW CHARACTER SET
     SHOW COLLATION
     SHOW COLUMNS
     SHOW DATABASES
     SHOW FUNCTION STATUS
     SHOW INDEX
     SHOW OPEN TABLES
     SHOW PROCEDURE STATUS
     SHOW STATUS
     SHOW TABLE STATUS
     SHOW TABLES
     SHOW TRIGGERS
     SHOW VARIABLES

The `WHERE' clause, if present, is evaluated against the column names
displayed by the *Note `SHOW': show. statement. For example, the *Note
`SHOW CHARACTER SET': show-character-set. statement produces these
output columns:

     mysql> SHOW CHARACTER SET;
     +----------+-----------------------------+---------------------+--------+
     | Charset  | Description                 | Default collation   | Maxlen |
     +----------+-----------------------------+---------------------+--------+
     | big5     | Big5 Traditional Chinese    | big5_chinese_ci     |      2 |
     | dec8     | DEC West European           | dec8_swedish_ci     |      1 |
     | cp850    | DOS West European           | cp850_general_ci    |      1 |
     | hp8      | HP West European            | hp8_english_ci      |      1 |
     | koi8r    | KOI8-R Relcom Russian       | koi8r_general_ci    |      1 |
     | latin1   | cp1252 West European        | latin1_swedish_ci   |      1 |
     | latin2   | ISO 8859-2 Central European | latin2_general_ci   |      1 |
     ...

To use a `WHERE' clause with *Note `SHOW CHARACTER SET':
show-character-set, you would refer to those column names. As an
example, the following statement displays information about character
sets for which the default collation contains the string `'japanese'':

     mysql> SHOW CHARACTER SET WHERE `Default collation` LIKE '%japanese%';
     +---------+---------------------------+---------------------+--------+
     | Charset | Description               | Default collation   | Maxlen |
     +---------+---------------------------+---------------------+--------+
     | ujis    | EUC-JP Japanese           | ujis_japanese_ci    |      3 |
     | sjis    | Shift-JIS Japanese        | sjis_japanese_ci    |      2 |
     | cp932   | SJIS for Windows Japanese | cp932_japanese_ci   |      2 |
     | eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci |      3 |
     +---------+---------------------------+---------------------+--------+

This statement displays the multi-byte character sets:

     mysql> SHOW CHARACTER SET WHERE Maxlen > 1;
     +---------+---------------------------+---------------------+--------+
     | Charset | Description               | Default collation   | Maxlen |
     +---------+---------------------------+---------------------+--------+
     | big5    | Big5 Traditional Chinese  | big5_chinese_ci     |      2 |
     | ujis    | EUC-JP Japanese           | ujis_japanese_ci    |      3 |
     | sjis    | Shift-JIS Japanese        | sjis_japanese_ci    |      2 |
     | euckr   | EUC-KR Korean             | euckr_korean_ci     |      2 |
     | gb2312  | GB2312 Simplified Chinese | gb2312_chinese_ci   |      2 |
     | gbk     | GBK Simplified Chinese    | gbk_chinese_ci      |      2 |
     | utf8    | UTF-8 Unicode             | utf8_general_ci     |      3 |
     | ucs2    | UCS-2 Unicode             | ucs2_general_ci     |      2 |
     | cp932   | SJIS for Windows Japanese | cp932_japanese_ci   |      2 |
     | eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci |      3 |
     +---------+---------------------------+---------------------+--------+


File: manual.info,  Node: connectors-apis,  Next: extending-mysql,  Prev: information-schema,  Up: Top

20 Connectors and APIs
**********************

* Menu:

* connector-odbc::               MySQL Connector/ODBC
* connector-net::                MySQL Connector/NET
* connector-vstudio::            MySQL Visual Studio Plugin
* connector-j::                  MySQL Connector/J
* connector-mxj::                MySQL Connector/MXJ
* connector-cpp::                MySQL Connector/C++
* connector-c::                  MySQL Connector/C
* connector-ooo::                MySQL Connector/OpenOffice.org
* libmysqld::                    libmysqld, the Embedded MySQL Server Library
* c::                            MySQL C API
* apis-php::                     MySQL PHP API
* apis-perl::                    MySQL Perl API
* apis-cplusplus::               MySQL C++ API
* apis-python::                  MySQL Python API
* apis-ruby::                    MySQL Ruby APIs
* apis-tcl::                     MySQL Tcl API
* apis-eiffel::                  MySQL Eiffel Wrapper

MySQL Connectors provide connectivity to the MySQL server for client
programs. APIs provide low-level access to the MySQL protocol and MySQL
resources. Both Connectors and the APIs enable you to connect and
execute MySQL statements from another language or environment,
including Java (JDBC), ODBC, Perl, Python, PHP, Ruby, and native C and
embedded MySQL instances.

*Note*:

Connector version numbers do not correlate with MySQL Server version
numbers. See also *Note connectors-apis-versions::.

A number of connectors are developed by MySQL:

   * Connector/ODBC provides driver support for connecting to a MySQL
     server using the Open Database Connectivity (ODBC) API. Support is
     available for ODBC connectivity from Windows, Unix and Mac OS X
     platforms.

   * Connector/NET enables developers to create .NET applications that
     use data stored in a MySQL database. Connector/NET implement a
     fully-functional ADO.NET interface and provides support for use
     with ADO.NET aware tools. Applications that want to use
     Connector/NET can be written in any of the supported .NET
     languages.

     The MySQL Visual Studio Plugin works with Connector/NET and Visual
     Studio 2005. The plugin is a MySQL DDEX Provider, which means that
     you can use the schema and data manipulation tools within Visual
     Studio to create and edit objects within a MySQL database.

   * Connector/J provides driver support for connecting to MySQL from a
     Java application using the standard Java Database Connectivity
     (JDBC) API.

   * Connector/MXJ is a tool that enables easy deployment and
     management of MySQL server and database through your Java
     application.

   * Connector/C++ is a tool that enables easy deployment and
     management of MySQL server and database through your C++
     application.

   * Connector/C is a stand-alone replacement for the MySQL Client
     Library (`libmysql').

   * Connector/OpenOffice.org is a tool that enables OpenOffice.org
     applications to connect to MySQL server.

There are two direct access methods for using MySQL natively within a C
application:

   * The C API provides low-level access to the MySQL protocol through
     the `libmysql' client library; this is the primary method used to
     connect to an instance of the MySQL server, and is used both by
     MySQL command line clients and many of the APIs also detailed in
     this section. MySQL Connector/C can now also be used for this
     purpose.

   * `libmysqld' is an embedded MySQL server library that enables you
     to embed an instance of the MySQL server into your C applications.

If you need to access MySQL from a C application, or build an interface
to MySQL for a language not supported by the Connectors or APIs in this
chapter, the C API is where you would start. A number of programmers
utilities are available to help with the process, and also covered in
this section.

The remaining APIs provide an interface to MySQL from specific
application langauges. These solutions are not developed or supported
by MySQL. Basic information on their usage and abilities is provided
here for reference purposes only.

All the language APIs are developed using one of two methods, using
`libmysql' or by building a _native driver_. The two solutions offer
different benefits:

   * Using _`libmysql'_ offers complete compatibility with MySQL as it
     uses the same libraries as the MySQL client applications. However,
     the feature set is limited to the implementation and interfaces
     exposed through `libmysql' and the performance may be lower as
     data is copied between the native langiage, and the MySQL API
     components. MySQL Connector/C is a possible alternative to using
     `libmysql'.

   * _Native drivers_ are an implementation of the MySQL network
     protocol entirely within the host language or environment. Native
     drivers are fast, as there is less copying of data between
     components, and they can offer advanced functionality not
     available through the standard MySQL API.  Native drivers are also
     easier to build and deploy, as you do not need a copy of the MySQL
     client libraries to build the native driver components.

A list of many of the libraries and interfaces available for MySQL are
shown in the table. See *Note connectors-apis-summary::.

*MySQL APIs and Interfaces*

EnvironmentAPI                       Type        Notes
Ada     MySQL Bindings for GNU    `libmysql'  See MySQL Bindings for GNU
        Ada                                   Ada
                                              (http://gnade.sourceforge.net/)
C       Connector/C               Replacement See *Note connector-c::.
                                  for         
                                  `libmysql'  
C++     Connector/C++             `libmysql'  See *Note connector-cpp::.
        MySQL++                   `libmysql'  See *Note apis-cplusplus::.
        MySQL wrapped             `libmysql'  See MySQL wrapped
                                              (http://www.alhem.net/project/mysql/).
Cocoa   MySQL-Cocoa               `libmysql'  Compatible with the
                                              Objective-C Cocoa
                                              environment. See
                                              `http://mysql-cocoa.sourceforge.net/'
D       MySQL for D               `libmysql'  See MySQL for D
                                              (http://www.steinmole.de/d/).
Eiffel  Eiffel MySQL              `libmysql'  See *Note apis-eiffel::.
Erlang  `erlang-mysql-driver'     `libmysql'  See `erlang-mysql-driver'.
                                              (http://code.google.com/p/erlang-mysql-driver/)
Haskell Haskell MySQL Bindings    Native      See Brian O'Sullivan's pure
                                  Driver      Haskell MySQL bindings
                                              (http://www.serpentine.com/software/mysql).
        `hsql-mysql'              `libmysql'  See MySQL driver for Haskell
                                              (http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hsql-mysql-1.7).
Java/JDBCConnector/J               Native      See *Note connector-j::.
                                  Driver      
Kaya    MyDB                      `libmysql'  See MyDB
                                              (http://kayalang.org/library/latest/MyDB).
Lua     LuaSQL                    `libmysql'  See LuaSQL
                                              (http://www.keplerproject.org/luasql/).
.NET/MonoConnector/NET             Native      See *Note connector-net::.
                                  Driver      
ObjectiveMySQL Bindings for        `libmysql'  See MySQL Bindings for
Caml    OBjective Caml                        Objective Caml
                                              (http://raevnos.pennmush.org/code/ocaml-mysql/).
Octave  Database bindings for     `libmysql'  See Database bindings for
        GNU Octave                            GNU Octave
                                              (http://octave.sourceforge.net/database/index.html).
ODBC    Connector/ODBC            `libmysql'  See *Note connector-odbc::.
OpenOfficeMySQL                     `libmysql'  Direct connectivity, without
        Connector/OpenOffice.org              using JDBC/ODBC. See *Note
                                              connector-ooo::.
Perl    `DBI'/`DBD::mysql'        `libmysql'  See *Note apis-perl::.
        `Net::MySQL'              Native      See `Net::MySQL'
                                  Driver      (http://search.cpan.org/dist/Net-MySQL/MySQL.pm)
                                              at CPAN
PHP     `mysql', `ext/mysql'      `libmysql'  See See section
        interface (deprecated)                "apis-php-mysql" in the
                                              online manual.
        `mysqli', `ext/mysqli'    `libmysql'  See See section
        interface                             "apis-php-mysqli" in the
                                              online manual.
        `PDO_MYSQL'               `libmysql'  See See section
                                              "apis-php-ref.pdo-mysql" in
                                              the online manual.
        PDO mysqlnd               Native      See PHP PDO `mysqlnd'.
                                  Driver      (http://forge.mysql.com/wiki/PHP_PDO_MYSQLND)
Python  MySQLdb                   `libmysql'  See *Note apis-python::.
Ruby    MySQL/Ruby                `libmysql'  Uses `libmysql'. See *Note
                                              apis-ruby-mysqlruby::.
        Ruby/MySQL                Native      See *Note
                                  Driver      apis-ruby-rubymysql::.
Scheme  `Myscsh'                  `libmysql'  See `Myscsh'
                                              (http://www-pu.informatik.uni-tuebingen.de/users/knauel/myscsh/).
SPL     `sql_mysql'               `libmysql'  See `sql_mysql' for SPL
                                              (http://www.clifford.at/spl/spldoc/sql_mysql.html).
Tcl     MySQLtcl                  `libmysql'  See *Note apis-tcl::.

*MySQL Connector versions and MySQL Server versions*

Connector                            Connector version  MySQL Server
                                                        version
Connector/C                          6.0.0 (Beta)       6.0
Connector/C++                        1.0.5 (Beta)       5.1, 6.0
Connector/OpenOffice.org             1.0 (Alpha)        5.0, 5.1, 6.0
Connector/J                          5.1                4.1, 5.0, 5.1, 6.0
Connector/NET                        1.0                4.0, 5.0
Connector/NET                        5.2                4.0, 4.1, 5.0,
                                                        5.1, 6.0
Connector/NET                        5.3                4.1, 5.0, 5.1, 6.0
Connector/ODBC                       3.51 (Unicode not  4.1, 5.0, 5.1, 6.0
                                     supported)         
Connector/ODBC                       5.1                4.1, 5.0, 5.1, 6.0


File: manual.info,  Node: connector-odbc,  Next: connector-net,  Prev: connectors-apis,  Up: connectors-apis

20.1 MySQL Connector/ODBC
=========================

* Menu:

* connector-odbc-versions::      Connector/ODBC Versions
* connector-odbc-introduction::  Connector/ODBC Introduction
* connector-odbc-installation::  Connector/ODBC Installation
* connector-odbc-configuration::  Connector/ODBC Configuration
* connector-odbc-examples::      Connector/ODBC Examples
* connector-odbc-reference::     Connector/ODBC Reference
* connector-odbc-usagenotes::    Connector/ODBC Notes and Tips
* connector-odbc-support::       Connector/ODBC Support

The MySQL Connector/ODBC is the name for the family of MySQL ODBC
drivers (previously called MyODBC drivers) that provide access to a
MySQL database using the industry standard Open Database Connectivity
(ODBC) API. This reference covers Connector/ODBC 3.51 and
Connector/ODBC 5.1. Both releases provide an ODBC compliant interface
to MySQL Server.

MySQL Connector/ODBC provides both driver-manager based and native
interfaces to the MySQL database, which full support for MySQL
functionality, including stored procedures, transactions and, with
Connector/ODBC 5.1, full Unicode compliance.

For more information on the ODBC API standard and how to use it, refer
to `http://support.microsoft.com/kb/110093'.

The application development part of this reference assumes a good
working knowledge of C, general DBMS knowledge, and finally, but not
least, familiarity with MySQL. For more information about MySQL
functionality and its syntax, refer to `http://dev.mysql.com/doc/'.

Typically, you need to install Connector/ODBC only on Windows machines.
For Unix and Mac OS X you can use the native MySQL network or named
pipe to communicate with your MySQL database. You may need
Connector/ODBC for Unix or Mac OS X if you have an application that
requires an ODBC interface to communicate with the database.
Applications that require ODBC to communicate with MySQL include
ColdFusion, Microsoft Office, and Filemaker Pro.

*Key topics:*

   * For help installing Connector/ODBC see *Note
     connector-odbc-installation::.

   * For information on the configuration options, see *Note
     connector-odbc-configuration-connection-parameters::.

   * For more information on connecting to a MySQL database from a
     Windows host using Connector/ODBC see *Note
     connector-odbc-examples-walkthrough::.

   * If you want to use Microsoft Access as an interface to a MySQL
     database using Connector/ODBC see *Note
     connector-odbc-examples-tools-with-access::.

   * General tips on using Connector/ODBC, including obtaining the last
     auto-increment ID see *Note
     connector-odbc-usagenotes-functionality::.

   * For tips and common questions on using Connector/ODBC with
     specific application see *Note connector-odbc-usagenotes-apptips::.

   * For a general list of Frequently Asked Questions see *Note
     connector-odbc-errors::.

   * Additional support when using Connector/ODBC is available, see
     *Note connector-odbc-support::.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about MySQL and
ODBC in the Knowledge Base articles about ODBC
(https://kb.mysql.com/search.php?cat=search&category=9). Access to the
MySQL Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: connector-odbc-versions,  Next: connector-odbc-introduction,  Prev: connector-odbc,  Up: connector-odbc

20.1.1 Connector/ODBC Versions
------------------------------

There are currently two version of Connector/ODBC available:

   * Connector/ODBC 5.1, currently in GA status, is a partial rewrite
     of the of the 3.51 code base and is designed to work with all
     versions of MySQL from 4.1. Connector/ODBC 5.1 will be a complete
     implementation of the ODBC Core interface,plus more Level 1 and
     Level 2 functionality of the ODBC specification than that
     currently supported by Connector/ODBC 3.51. See *Note
     connector-odbc-roadmap::.

     Connector/ODBC 5.1 also includes the following changes and
     improvements over the 3.51 release:

        * Improved support on Windows 64-bit platforms.

        * Full Unicode support at the driver level. This includes
          support for the `SQL_WCHAR' datatype, and support for Unicode
          login, password and DSN configurations. For more
          information,. see Microsoft Knowledgebase Article #716246
          (http://msdn2.microsoft.com/en-us/library/ms716246.aspx).

        * Support for the `SQL_NUMERIC_STRUCT' datatype, which provides
          easier access to the precise definition of numeric values.
          For more information, see Microsoft Knowledgebase Article
          #714556
          (http://msdn2.microsoft.com/en-us/library/ms714556.aspx)

        * Native Windows setup library. This replaces the Qt library
          based interface for configuring DSN information within the
          ODBC Data Sources application.

        * Support for the ODBC descriptor, which improves the handling
          and metadata of columns and parameter data. For more
          information, see Microsoft Knowledgebase Article #716339
          (http://msdn2.microsoft.com/en-us/library/ms716339.aspx).

   * Connector/ODBC 3.51 is the current release of the 32-bit ODBC
     driver, also known as the MySQL ODBC 3.51 driver.  Connector/ODBC
     3.51 has support for ODBC 3.5x specification level 1 (complete
     core API + level 2 features) in order to continue to provide all
     functionality of ODBC for accessing MySQL.

The manual for versions of Connector/ODBC older than 3.51 can be
located in the corresponding binary or source distribution. Please note
that versions of Connector/ODBC earlier than the 3.51 revision were not
fully compliant with the ODBC specification.

*Note*:

Development on Connector/ODBC 5.0 was stopped due to development
issues. Connector/ODBC 5.1 is now the current development release.

*Note*:

From this section onward, the primary focus of this guide is the
Connector/ODBC 3.51 and Connector/ODBC 5.1 drivers.

*Note*:

Version numbers for MySQL products are formatted as X.X.X.  However,
Windows tools (Control Panel, properties display) may show the version
numbers as XX.XX.XX. For example, the official MySQL formatted version
number 5.0.9 may be displayed by Windows tools as 5.00.09. The two
versions are the same; only the number display format is different.


File: manual.info,  Node: connector-odbc-introduction,  Next: connector-odbc-installation,  Prev: connector-odbc-versions,  Up: connector-odbc

20.1.2 Connector/ODBC Introduction
----------------------------------

* Menu:

* connector-odbc-roadmap::       Connector/ODBC Roadmap
* connector-odbc-general-information::  General Information About ODBC and Connector/ODBC

ODBC (Open Database Connectivity) provides a way for client programs to
access a wide range of databases or data sources. ODBC is a
standardized API that allows connections to SQL database servers. It
was developed according to the specifications of the SQL Access Group
and defines a set of function calls, error codes, and data types that
can be used to develop database-independent applications. ODBC usually
is used when database independence or simultaneous access to different
data sources is required.

For more information about ODBC, refer to
`http://support.microsoft.com/kb/110093'.


File: manual.info,  Node: connector-odbc-roadmap,  Next: connector-odbc-general-information,  Prev: connector-odbc-introduction,  Up: connector-odbc-introduction

20.1.2.1 Connector/ODBC Roadmap
...............................

Connector/ODBC 5.1 is currently in development and will be a complete
implementation of the ODBC Core interface,plus more Level 1 and Level 2
functionality of the ODBC specification than that currently supported
by Connector/ODBC 3.51.

The following functionality was added or changed as part of 5.1:

   * Add support for SQL_NUMERIC_STRUCT: MSDN Article 714556
     (http://msdn2.microsoft.com/en-us/library/ms714556.aspx).

   * Replace installer library with new implementation (from v5 tree).

   * Implement native Windows setup library.

   * Implement SQLCancel() (Bug#15601 (http://bugs.mysql.com/15601)):
     MSDN Article 714112
     (http://msdn2.microsoft.com/en-us/library/ms714112.aspx).

The following functionality will be added in a version after 5.1:

   * Implement native Mac OS X setup library.

   * Replace OPTIONS flags with individual DSN settings (but support
     OPTIONS for backwards-compatibility).

   * Fix support for SQLBIGINT (Bug#28887
     (http://bugs.mysql.com/28887)): MSDN Article 714121
     (http://msdn2.microsoft.com/en-us/library/ms714121.aspx).

   * Make diagnostics support standards-compliant: MSDN Article 711021
     (http://msdn2.microsoft.com/en-us/library/ms711021.aspx).

   * Add support for SQL_ATTR_METADATA_ID: MSDN Article 716447
     (http://msdn2.microsoft.com/en-us/library/ms716447.aspx).

   * Implement SQLBrowseConnect(): MSDN Article 714565
     (http://msdn2.microsoft.com/en-us/library/ms714565.aspx), MSDN
     Article 712446
     (http://msdn2.microsoft.com/en-us/library/ms712446.aspx).

   * Implement arrays of parameters: MSDN Article 711818
     (http://msdn2.microsoft.com/en-us/library/ms711818.aspx).


File: manual.info,  Node: connector-odbc-general-information,  Prev: connector-odbc-roadmap,  Up: connector-odbc-introduction

20.1.2.2 General Information About ODBC and Connector/ODBC
..........................................................

* Menu:

* connector-odbc-architecture::  Connector/ODBC Architecture
* connector-odbc-driver-manager::  ODBC Driver Managers

Open Database Connectivity (ODBC) is a widely accepted
application-programming interface (API) for database access. It is
based on the Call-Level Interface (CLI) specifications from X/Open and
ISO/IEC for database APIs and uses Structured Query Language (SQL) as
its database access language.

A survey of ODBC functions supported by Connector/ODBC is given at
*Note connector-odbc-reference-api::. For general information about
ODBC, see `http://support.microsoft.com/kb/110093'.


File: manual.info,  Node: connector-odbc-architecture,  Next: connector-odbc-driver-manager,  Prev: connector-odbc-general-information,  Up: connector-odbc-general-information

20.1.2.3 Connector/ODBC Architecture
....................................

The Connector/ODBC architecture is based on five components, as shown
in the following diagram:

Connector/ODBC Architecture

   * *Application:*

     The Application uses the ODBC API to access the data from the
     MySQL server. The ODBC API in turn uses the communicates with the
     Driver Manager. The Application communicates with the Driver
     Manager using the standard ODBC calls. The Application does not
     care where the data is stored, how it is stored, or even how the
     system is configured to access the data. It needs to know only the
     Data Source Name (DSN).

     A number of tasks are common to all applications, no matter how
     they use ODBC. These tasks are:

        * Selecting the MySQL server and connecting to it

        * Submitting SQL statements for execution

        * Retrieving results (if any)

        * Processing errors

        * Committing or rolling back the transaction enclosing the SQL
          statement

        * Disconnecting from the MySQL server

     Because most data access work is done with SQL, the primary tasks
     for applications that use ODBC are submitting SQL statements and
     retrieving any results generated by those statements.

   * *Driver manager:*

     The Driver Manager is a library that manages communication between
     application and driver or drivers. It performs the following tasks:

        * Resolves Data Source Names (DSN). The DSN is a configuration
          string that identifies a given database driver, database,
          database host and optionally authentication information that
          enables an ODBC application to connect to a database using a
          standardized reference.

          Because the database connectivity information is identified
          by the DSN, any ODBC compliant application can connect to the
          data source using the same DSN reference. This eliminates the
          need to separately configure each application that needs
          access to a given database; instead you instruct the
          application to use a pre-configured DSN.

        * Loading and unloading of the driver required to access a
          specific database as defined within the DSN. For example, if
          you have configured a DSN that connects to a MySQL database
          then the driver manager will load the Connector/ODBC driver
          to enable the ODBC API to communicate with the MySQL host.

        * Processes ODBC function calls or passes them to the driver
          for processing.

   * *Connector/ODBC Driver:*

     The Connector/ODBC driver is a library that implements the
     functions supported by the ODBC API. It processes ODBC function
     calls, submits SQL requests to MySQL server, and returns results
     back to the application. If necessary, the driver modifies an
     application's request so that the request conforms to syntax
     supported by MySQL.

   * *DSN Configuration:*

     The ODBC configuration file stores the driver and database
     information required to connect to the server. It is used by the
     Driver Manager to determine which driver to be loaded according to
     the definition in the DSN. The driver uses this to read connection
     parameters based on the DSN specified. For more information, *Note
     connector-odbc-configuration::.

   * *MySQL Server:*

     The MySQL database where the information is stored. The database
     is used as the source of the data (during queries) and the
     destination for data (during inserts and updates).


File: manual.info,  Node: connector-odbc-driver-manager,  Prev: connector-odbc-architecture,  Up: connector-odbc-general-information

20.1.2.4 ODBC Driver Managers
.............................

An ODBC Driver Manager is a library that manages communication between
the ODBC-aware application and any drivers. Its main functionality
includes:

   * Resolving Data Source Names (DSN).

   * Driver loading and unloading.

   * Processing ODBC function calls or passing them to the driver.

Both Windows and Mac OS X include ODBC driver managers with the
operating system. Most ODBC Driver Manager implementations also include
an administration application that makes the configuration of DSN and
drivers easier. Examples and information on these managers, including
Unix ODBC driver managers are listed below:

   * Microsoft Windows ODBC Driver Manager (`odbc32.dll'),
     `http://support.microsoft.com/kb/110093'.

   * Mac OS X includes `ODBC Administrator', a GUI application that
     provides a simpler configuration mechanism for the Unix iODBC
     Driver Manager. You can configure DSN and driver information
     either through ODBC Administrator or through the iODBC
     configuration files.  This also means that you can test ODBC
     Administrator configurations using the `iodbctest' command.
     `http://www.apple.com'.

   * `unixODBC' Driver Manager for Unix (`libodbc.so'). See
     `http://www.unixodbc.org', for more information. The `unixODBC'
     Driver Manager includes the Connector/ODBC driver 3.51 in the
     installation package, starting with version `unixODBC' 2.1.2.

   * `iODBC' ODBC Driver Manager for Unix (`libiodbc.so'), see
     `http://www.iodbc.org', for more information.


File: manual.info,  Node: connector-odbc-installation,  Next: connector-odbc-configuration,  Prev: connector-odbc-introduction,  Up: connector-odbc

20.1.3 Connector/ODBC Installation
----------------------------------

* Menu:

* connector-odbc-installation-binary-windows::  Installing Connector/ODBC from a Binary Distribution on Windows
* connector-odbc-installation-binary-unix::  Installing Connector/ODBC from a Binary Distribution on Unix
* connector-odbc-installation-binary-macosx::  Installing Connector/ODBC from a Binary Distribution on Mac OS X
* connector-odbc-installation-source-windows::  Installing Connector/ODBC from a Source Distribution on Windows
* connector-odbc-installation-source-unix::  Installing Connector/ODBC from a Source Distribution on Unix
* connector-odbc-installation-source-development::  Installing Connector/ODBC from the Development Source Tree

You can install the Connector/ODBC drivers using two different methods,
a binary installation and a source installation. The binary
installation is the easiest and most straightforward method of
installation. Using the source installation methods should only be
necessary on platforms where a binary installation package is not
available, or in situations where you want to customize or modify the
installation process or Connector/ODBC drivers before installation.

*Where to Get Connector/ODBC*

Sun Microsystems, Inc distributes its MySQL products under the General
Public License (GPL). You can get a copy of the latest version of
Connector/ODBC binaries and sources from our Web site at
`http://dev.mysql.com/downloads/'.

For more information about Connector/ODBC, visit
`http://www.mysql.com/products/myodbc/'.

For more information about licensing, visit
`http://www.mysql.com/company/legal/licensing/'.

*Supported Platforms*

Connector/ODBC can be used on all major platforms supported by MySQL.
You can install it on:

   * Windows 95, 98, Me, NT, 2000, XP, and 2003

   * All Unix-like Operating Systems, including: AIX, Amiga, BSDI, DEC,
     FreeBSD, HP-UX 10/11, Linux, NetBSD, OpenBSD, OS/2, SGI Irix,
     Solaris, SunOS, SCO OpenServer, SCO UnixWare, Tru64 Unix

   * Mac OS X and Mac OS X Server

Using a binary distribution offers the most straightforward method for
installing Connector/ODBC. If you want more control over the driver,
the installation location and or to customize elements of the driver
you will need to build and install from the source.

If a binary distribution is not available for a particular platform
build the driver from the original source code. You can contribute the
binaries you create to MySQL by sending a mail message to
<myodbc@lists.mysql.com>, so that it becomes available for other users.

*Note*:

On all non-Windows platforms except Mac OS X, the driver is built
against `unixODBC' and is expecting a 2-byte `SQLWCHAR', not 4 bytes as
`iODBC' is using. For this reason, the binaries are *only* compatible
with `unixODBC' and you will need to recompile the driver against
`iODBC' if you wish to use them together. For further information see
*Note connector-odbc-driver-manager::.

For further instructions:

Platform               Binary                 Source
Windows                *Note Installation     *Note Build
                       Instructions:          Instructions:
                       connector-odbc-installation-binary-windows.connector-odbc-installation-source-windows.
Unix/Linux             *Note Installation     *Note Build
                       Instructions:          Instructions:
                       connector-odbc-installation-binary-unix.connector-odbc-installation-source-unix.
Mac OS X               *Note Installation     
                       Instructions:          
                       connector-odbc-installation-binary-macosx.


File: manual.info,  Node: connector-odbc-installation-binary-windows,  Next: connector-odbc-installation-binary-unix,  Prev: connector-odbc-installation,  Up: connector-odbc-installation

20.1.3.1 Installing Connector/ODBC from a Binary Distribution on Windows
........................................................................

* Menu:

* connector-odbc-installation-binary-windows-installer::  Installing the Windows Connector/ODBC Driver using an installer
* connector-odbc-installation-binary-windows-dll::  Installing the Windows Connector/ODBC Driver using the Zipped DLL package

Before installing the Connector/ODBC drivers on Windows you should
ensure that your Microsoft Data Access Components (MDAC) are up to
date. You can obtain the latest version from the Microsoft Data Access
and Storage (http://support.microsoft.com/kb/110093) Web site.

There are three available distribution types to use when installing for
Windows. The contents in each case are identical, it is only the
installation method which is different.

   * Zipped installer consists of a Zipped package containing a
     standalone installation application. To install from this package,
     you must unzip the installer, and then run the installation
     application. See *Note
     connector-odbc-installation-binary-windows-installer:: to complete
     the installation.

   * MSI installer, an installation file that can be used with the
     installer included in Windows 2000, Windows XP and Windows Server
     2003. See *Note
     connector-odbc-installation-binary-windows-installer:: to complete
     the installation.

   * Zipped DLL package, containing the DLL files that need must be
     manually installed. See *Note
     connector-odbc-installation-binary-windows-dll:: to complete the
     installation.

*Note*:

An OLEDB/ODBC driver for Windows 64-bit is available from Microsoft
Downloads
(http://www.microsoft.com/downloads/details.aspx?FamilyID=000364db-5e8b-44a8-b9be-ca44d18b059b&displaylang=en).


File: manual.info,  Node: connector-odbc-installation-binary-windows-installer,  Next: connector-odbc-installation-binary-windows-dll,  Prev: connector-odbc-installation-binary-windows,  Up: connector-odbc-installation-binary-windows

20.1.3.2 Installing the Windows Connector/ODBC Driver using an installer
........................................................................

The installer packages offer a very simple method for installing the
Connector/ODBC drivers. If you have downloaded the zipped installer
then you must extract the installer application. The basic installation
process is identical for both installers.

You should follow these steps to complete the installation:

  1. Double click on the standalone installer that you extracted, or
     the MSI file you downloaded.

  2. The MySQL Connector/ODBC 3.51 - Setup Wizard will start.  Click
     the `Next' button to begin the installation process.

     Connector/ODBC Windows Installer - Welcome

  3. You will need to choose the installation type. The Typical
     installation provides the standard files you will need to connect
     to a MySQL database using ODBC. The Complete option installs all
     the available files, including debug and utility components. It is
     recommended you choose one of these two options to complete the
     installation. If choose one of these methods, click `Next' and
     then proceed to step 5.

     You may also choose a Custom installation, which enables you to
     select the individual components that you want to install. You
     have chosen this method, click `Next' and then proceed to step 4.

     Connector/ODBC Windows Installer - Choosing a Setup type welcome

  4. If you have chosen a custom installation, use the pop-ups to
     select which components to install and then click `Next' to
     install the necessary files.

     Connector/ODBC Windows Installer - Custom Installation welcome

  5. Once the files have copied to your machine, the installation is
     complete. Click `Finish' to exit the installer.

     Connector/ODBC Windows Installer - Completion welcome

Now the installation is complete, you can continue to configure your
ODBC connections using *Note connector-odbc-configuration::.


File: manual.info,  Node: connector-odbc-installation-binary-windows-dll,  Prev: connector-odbc-installation-binary-windows-installer,  Up: connector-odbc-installation-binary-windows

20.1.3.3 Installing the Windows Connector/ODBC Driver using the Zipped DLL package
..................................................................................

If you have downloaded the Zipped DLL package then you must install the
individual files required for Connector/ODBC operation manually. Once
you have unzipped the installation files, you can either perform this
operation by hand, executing each statement individually, or you can
use the included Batch file to perform an installation to the default
locations.

To install using the Batch file:

  1. Unzip the Connector/ODBC Zipped DLL package.

  2. Open a Command Prompt.

  3. Change to the directory created when you unzipped the
     Connector/ODBC Zipped DLL package.

  4. Run `Install.bat:'

          C:\> Install.bat

     This will copy the necessary files into the default location, and
     then register the Connector/ODBC driver with the Windows ODBC
     manager.

If you want to copy the files to an alternative location - for example,
to run or test different versions of the Connector/ODBC driver on the
same machine, then you must copy the files by hand. It is however not
recommended to install these files in a non-standard location. To copy
the files by hand to the default installation location use the following
steps:

  1. Unzip the Connector/ODBC Zipped DLL package.

  2. Open a Command Prompt.

  3. Change to the directory created when you unzipped the
     Connector/ODBC Zipped DLL package.

  4. Copy the library files to a suitable directory. The default is to
     copy them into the default Windows system directory
     `\Windows\System32':

          C:\> copy lib\myodbc3S.dll \Windows\System32
          C:\> copy lib\myodbc3S.lib \Windows\System32
          C:\> copy lib\myodbc3.dll \Windows\System32
          C:\> copy lib\myodbc3.lib \Windows\System32

  5. Copy the Connector/ODBC tools. These must be placed into a
     directory that is in the system `PATH'.  The default is to install
     these into the Windows system directory `\Windows\System32':

          C:\> copy bin\myodbc3i.exe \Windows\System32
          C:\> copy bin\myodbc3m.exe \Windows\System32
          C:\> copy bin\myodbc3c.exe \Windows\System32

  6. Optionally copy the help files. For these files to be accessible
     through the help system, they must be installed in the Windows
     system directory:

          C:\> copy doc\*.hlp \Windows\System32

  7. Finally, you must register the Connector/ODBC driver with the ODBC
     manager:

          C:\> myodbc3i -a -d -t"MySQL ODBC 3.51 Driver;\
            DRIVER=myodbc3.dll;SETUP=myodbc3S.dll"

     You must change the references to the DLL files and command
     location in the above statement if you have not installed these
     files into the default location.


File: manual.info,  Node: connector-odbc-installation-binary-unix,  Next: connector-odbc-installation-binary-macosx,  Prev: connector-odbc-installation-binary-windows,  Up: connector-odbc-installation

20.1.3.4 Installing Connector/ODBC from a Binary Distribution on Unix
.....................................................................

* Menu:

* connector-odbc-installation-binary-unix-tarball::  Installing Connector/ODBC from a Binary Tarball Distribution
* connector-odbc-installation-binary-unix-rpm::  Installing Connector/ODBC from an RPM Distribution

There are two methods available for installing Connector/ODBC on Unix
from a binary distribution. For most Unix environments you will need to
use the tarball distribution. For Linux systems, there is also an RPM
distribution available.

*Note*:

To install Connector/ODBC 5.1 on Unix you require unixODBC 2.2.12 or
later to be installed.


File: manual.info,  Node: connector-odbc-installation-binary-unix-tarball,  Next: connector-odbc-installation-binary-unix-rpm,  Prev: connector-odbc-installation-binary-unix,  Up: connector-odbc-installation-binary-unix

20.1.3.5 Installing Connector/ODBC from a Binary Tarball Distribution
.....................................................................

To install the driver from a tarball distribution (`.tar.gz' file),
download the latest version of the driver for your operating system and
follow these steps that demonstrate the process using the Linux version
of the tarball:

     shell> su root
     shell> gunzip mysql-connector-odbc-3.51.11-i686-pc-linux.tar.gz
     shell> tar xvf mysql-connector-odbc-3.51.11-i686-pc-linux.tar
     shell> cd mysql-connector-odbc-3.51.11-i686-pc-linux

Read the installation instructions in the `INSTALL' file and execute
these commands.

Then proceed on to *Note connector-odbc-configuration-dsn-unix::, to
configure the DSN for Connector/ODBC. For more information, refer to
the `INSTALL' file that comes with your distribution.


File: manual.info,  Node: connector-odbc-installation-binary-unix-rpm,  Prev: connector-odbc-installation-binary-unix-tarball,  Up: connector-odbc-installation-binary-unix

20.1.3.6 Installing Connector/ODBC from an RPM Distribution
...........................................................

To install or upgrade Connector/ODBC from an RPM distribution on Linux,
simply download the RPM distribution of the latest version of
Connector/ODBC and follow the instructions below.  Use `su root' to
become `root', then install the RPM file.

If you are installing for the first time:

     shell> su root
      shell> rpm -ivh mysql-connector-odbc-3.51.12.i386.rpm

If the driver exists, upgrade it like this:

     shell> su root
     shell> rpm -Uvh mysql-connector-odbc-3.51.12.i386.rpm

If there is any dependency error for MySQL client library,
`libmysqlclient', simply ignore it by supplying the `--nodeps' option,
and then make sure the MySQL client shared library is in the path or set
through `LD_LIBRARY_PATH'.

This installs the driver libraries and related documents to
`/usr/local/lib' and `/usr/share/doc/MyODBC', respectively.  Proceed
onto *Note connector-odbc-configuration-dsn-unix::.

To *uninstall* the driver, become `root' and execute an `rpm' command:

     shell> su root
     shell> rpm -e mysql-connector-odbc


File: manual.info,  Node: connector-odbc-installation-binary-macosx,  Next: connector-odbc-installation-source-windows,  Prev: connector-odbc-installation-binary-unix,  Up: connector-odbc-installation

20.1.3.7 Installing Connector/ODBC from a Binary Distribution on Mac OS X
.........................................................................

Mac OS X is based on the FreeBSD operating system, and you can normally
use the MySQL network port for connecting to MySQL servers on other
hosts. Installing the Connector/ODBC driver enables you to connect to
MySQL databases on any platform through the ODBC interface. You should
only need to install the Connector/ODBC driver when your application
requires an ODBC interface. Applications that require or can use ODBC
(and therefore the Connector/ODBC driver) include ColdFusion, Filemaker
Pro, 4th Dimension and many other applications.

Mac OS X includes its own ODBC manager, based on the `iODBC' manager.
Mac OS X includes an administration tool that provides easier
administration of ODBC drivers and configuration, updating the
underlying `iODBC' configuration files.

The method for installing Connector/ODBC on Mac OS X depends on the
version on Connector/ODBC you are using. For Connector/ODBC 3.51.14 and
later, the package is provided as a compressed tar archive that you
must manually install. For Connector/ODBC 3.51.13 and earlier the
software was provided on a compressed disk image (`.dmg') file and
included an installer.

In either case, the driver is designed to work with the iODBC driver
manager included with Mac OS X.

To install Connector/ODBC 3.51.14 and later:

  1. Download the installation file. Note that versions are available
     for both PowerPC and Intel platforms.

  2. Extract the archive:

          shell> tar zxf mysql-connector-odbc-3.51.16-osx10.4-x86-32bit.tar.gz

  3. The directory created will contain two subdirectories, `lib' and
     `bin'. You need to copy these to a suitable location such as
     `/usr/local':

          shell> cp bin/* /usr/local/bin
          shell> cp lib/* /usr/local/lib

  4. Finally, you must register the driver with iODBC using the
     `myodbc3i' tool you just installed:

          shell> myodbc3i -a -d -t"MySQL ODBC 3.51 Driver;Driver=/usr/local/lib/libmyodbc3.so;Setup=/usr/local/lib/libmyodbc3S.so"

You can verify the installed drivers either by using the ODBC
Administrator application or the `myodbc3i' utility:

     shell> myodbc3i -q -d

To install Connector/ODBC 3.51.13 and earlier, follow these steps:

  1. Download the file to your computer and double-click on the
     downloaded image file.

  2. Within the disk image you will find an installer package (with the
     `.pkg' extension). Double click on this file to start the Mac OS X
     installer.

  3. You will be presented with the installer welcome message.  Click
     the `Continue' button to begin the installation process.

     Connector/ODBC Mac OS X Installer - Installer welcome

  4. Please take the time to read the Important Information as it
     contains guidance on how to complete the installation process.
     Once you have read the notice and collected the necessary
     information, click `Continue'.

     Connector/ODBC Mac OS X Installer - Important Information

  5. Connector/ODBC drivers are made available under the GNU General
     Public License. Please read the license if you are not familiar
     with it before continuing installation. Click `Continue' to
     approve the license (you will be asked to confirm that decision)
     and continue the installation.

     Connector/ODBC Mac OS X Installer - License

  6. Choose a location to install the Connector/ODBC drivers and the
     ODBC Administrator application. You must install the files onto a
     drive with an operating system and you may be limited in the
     choices available. Select the drive you want to use, and then
     click `Continue'.

     Connector/ODBC Mac OS X Installer - Choosing a destination

  7. The installer will automatically select the files that need to be
     installed on your machine. Click `Install' to continue. The
     installer will copy the necessary files to your machine. A progress
     bar will be shown indicating the installation progress.

     Connector/ODBC Mac OS X Installer - Installation type

  8. When installation has been completed you will get a window like
     the one shown below. Click `Close' to close and quit the installer.

     Connector/ODBC Mac OS X Installer - Installation complete


File: manual.info,  Node: connector-odbc-installation-source-windows,  Next: connector-odbc-installation-source-unix,  Prev: connector-odbc-installation-binary-macosx,  Up: connector-odbc-installation

20.1.3.8 Installing Connector/ODBC from a Source Distribution on Windows
........................................................................

* Menu:

* connector-odbc-installation-source-windows-3-51-building::  Building Connector/ODBC 3.51
* connector-odbc-installation-source-windows-3-51-testing::  Testing

You should only need to install Connector/ODBC from source on Windows
if you want to change or modify the source or installation. If you are
unsure whether to install from source, please use the binary
installation detailed in *Note
connector-odbc-installation-binary-windows::.

Installing Connector/ODBC from source on Windows requires a number of
different tools and packages:

   * MDAC, Microsoft Data Access SDK from
     `http://support.microsoft.com/kb/110093'.

   * Suitable C compiler, such as Microsoft Visual C++ or the C
     compiler included with Microsoft Visual Studio.

   * Compatible `make' tool. Microsoft's `nmake' is used in the
     examples in this section.

   * MySQL client libraries and include files from MySQL 4.0.0 or
     higher. (Preferably MySQL 4.0.16 or higher). This is required
     because Connector/ODBC uses new calls and structures that exist
     only starting from this version of the library. To get the client
     libraries and include files, visit
     `http://dev.mysql.com/downloads/'.


File: manual.info,  Node: connector-odbc-installation-source-windows-3-51-building,  Next: connector-odbc-installation-source-windows-3-51-testing,  Prev: connector-odbc-installation-source-windows,  Up: connector-odbc-installation-source-windows

20.1.3.9 Building Connector/ODBC 3.51
.....................................

Connector/ODBC source distributions include `Makefiles' that require the
`nmake' or other `make' utility. In the distribution, you can find
`Makefile' for building the release version and `Makefile_debug' for
building debugging versions of the driver libraries and DLLs.

To build the driver, use this procedure:

  1. Download and extract the sources to a folder, then change
     directory into that folder. The following command assumes the
     folder is named `myodbc3-src':

          C:\> cd myodbc3-src

  2. Edit `Makefile' to specify the correct path for the MySQL client
     libraries and header files. Then use the following commands to
     build and install the release version:

          C:\> nmake -f Makefile
          C:\> nmake -f Makefile install

     `nmake -f Makefile' builds the release version of the driver and
     places the binaries in subdirectory called `Release'.

     `nmake -f Makefile install' installs (copies) the driver DLLs and
     libraries (`myodbc3.dll', `myodbc3.lib') to your system directory.

  3. To build the debug version, use `Makefile_Debug' rather than
     `Makefile', as shown below:

          C:\> nmake -f Makefile_debug
          C:\> nmake -f Makefile_debug install

  4. You can clean and rebuild the driver by using:

          C:\> nmake -f Makefile clean
          C:\> nmake -f Makefile install

*Note*:

   * Make sure to specify the correct MySQL client libraries and header
     files path in the Makefiles (set the `MYSQL_LIB_PATH' and
     `MYSQL_INCLUDE_PATH' variables). The default header file path is
     assumed to be `C:\mysql\include'. The default library path is
     assumed to be `C:\mysql\lib\opt' for release DLLs and
     `C:\mysql\lib\debug' for debug versions.

   * For the complete usage of `nmake', visit
     `http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dv_vcce4/html/evgrfRunningNMAKE.asp'.

   * If you are using the Subversion tree for compiling, all
     Windows-specific `Makefiles' are named as `Win_Makefile*'.


File: manual.info,  Node: connector-odbc-installation-source-windows-3-51-testing,  Prev: connector-odbc-installation-source-windows-3-51-building,  Up: connector-odbc-installation-source-windows

20.1.3.10 Testing
.................

After the driver libraries are copied/installed to the system
directory, you can test whether the libraries are properly built by
using the samples provided in the `samples' subdirectory:

     C:\> cd samples
     C:\> nmake -f Makefile all


File: manual.info,  Node: connector-odbc-installation-source-unix,  Next: connector-odbc-installation-source-development,  Prev: connector-odbc-installation-source-windows,  Up: connector-odbc-installation

20.1.3.11 Installing Connector/ODBC from a Source Distribution on Unix
......................................................................

* Menu:

* connector-odbc-installation-source-unix-configure-options::  Typical `configure' Options
* connector-odbc-installation-source-unix-otheroptions::  Additional configure Options
* connector-odbc-installation-source-unix-building::  Building and Compilation
* connector-odbc-installation-source-unix-shared-libraries::  Building Shared Libraries
* connector-odbc-installation-source-unix-installing::  Installing Driver Libraries
* connector-odbc-installation-source-unix-testing::  Testing Connector/ODBC on Unix
* connector-odbc-installation-source-unix-macosx::  Building Connector/ODBC from Source on Mac OS X
* connector-odbc-installation-source-unix-hpux::  Building Connector/ODBC from Source on HP-UX
* connector-odbc-installation-source-unix-aix::  Building Connector/ODBC from Source on AIX

You need the following tools to build MySQL from source on Unix:

   * A working ANSI C++ compiler. `gcc' 2.95.2 or later, SGI C++, and
     SunPro C++ are some of the compilers that are known to work.

   * A good `make' program. GNU `make' is always recommended and is
     sometimes required.

   * MySQL client libraries and include files from MySQL 4.0.0 or
     higher. (Preferably MySQL 4.0.16 or higher). This is required
     because Connector/ODBC uses new calls and structures that exist
     only starting from this version of the library. To get the client
     libraries and include files, visit
     `http://dev.mysql.com/downloads/'.

     If you have built your own MySQL server and/or client libraries
     from source then you must have used the
     `--enable-thread-safe-client' option to `configure' when the
     libraries were built.

     You should also ensure that the `libmysqlclient' library were
     built and installed as a shared library.

   * A compatible ODBC manager must be installed. Connector/ODBC is
     known to work with the `iODBC' and `unixODBC' managers. See *Note
     connector-odbc-driver-manager::, for more information.

   * If you are using a character set that isn't compiled into the
     MySQL client library then you need to install the MySQL character
     definitions from the `charsets' directory into SHAREDIR (by
     default, `/usr/local/mysql/share/mysql/charsets').  These should
     be in place if you have installed the MySQL server on the same
     machine. See *Note charset::, for more information on character
     set support.

Once you have all the required files, unpack the source files to a
separate directory, you then have to run `configure' and build the
library using `make'.


File: manual.info,  Node: connector-odbc-installation-source-unix-configure-options,  Next: connector-odbc-installation-source-unix-otheroptions,  Prev: connector-odbc-installation-source-unix,  Up: connector-odbc-installation-source-unix

20.1.3.12 Typical `configure' Options
.....................................

The `configure' script gives you a great deal of control over how you
configure your Connector/ODBC build.  Typically you do this using
options on the `configure' command line. You can also affect
`configure' using certain environment variables. For a list of options
and environment variables supported by `configure', run this command:

     shell> ./configure --help

Some of the more commonly used `configure' options are described here:

  1. To compile Connector/ODBC, you need to supply the MySQL client
     include and library files path using the `--with-mysql-path=DIR'
     option, where DIR is the directory where MySQL is installed.

     MySQL compile options can be determined by running
     `DIR/bin/mysql_config'.

  2. Supply the standard header and library files path for your ODBC
     Driver Manager (`iODBC' or `unixODBC').

        * If you are using `iODBC' and `iODBC' is not installed in its
          default location (`/usr/local'), you might have to use the
          `--with-iodbc=DIR' option, where DIR is the directory where
          `iODBC' is installed.

          If the `iODBC' headers do not reside in `DIR/include', you
          can use the `--with-iodbc-includes=INCDIR' option to specify
          their location.

          The applies to libraries. If they are not in `DIR/lib', you
          can use the `--with-iodbc-libs=LIBDIR' option.

        * If you are using `unixODBC', use the `--with-unixODBC=DIR'
          option (case sensitive) to make `configure' look for
          `unixODBC' instead of `iODBC' by default, DIR is the
          directory where `unixODBC' is installed.

          If the `unixODBC' headers and libraries aren't located in
          `DIR/include' and `DIR/lib', use the
          `--with-unixODBC-includes=INCDIR' and
          `--with-unixODBC-libs=LIBDIR' options.

  3. You might want to specify an installation prefix other than
     `/usr/local'. For example, to install the Connector/ODBC drivers in
     `/usr/local/odbc/lib', use the `--prefix=/usr/local/odbc' option.

The final configuration command looks something like this:

     shell> ./configure --prefix=/usr/local \
              --with-iodbc=/usr/local \
              --with-mysql-path=/usr/local/mysql


File: manual.info,  Node: connector-odbc-installation-source-unix-otheroptions,  Next: connector-odbc-installation-source-unix-building,  Prev: connector-odbc-installation-source-unix-configure-options,  Up: connector-odbc-installation-source-unix

20.1.3.13 Additional configure Options
......................................

There are a number of other options that you need, or want, to set when
configuring the Connector/ODBC driver before it is built.

   * To link the driver with MySQL thread safe client libraries
     `libmysqlclient_r.so' or `libmysqlclient_r.a', you must specify
     the following `configure' option:

          --enable-thread-safe

     and can be disabled (default) using

          --disable-thread-safe

     This option enables the building of the driver thread-safe library
     `libmyodbc3_r.so' from by linking with MySQL thread-safe client
     library `libmysqlclient_r.so' (The extensions are OS dependent).

     If the compilation with the thread-safe option fails, it may be
     because the correct thread-libraries on the system could not be
     located. You should set the value of `LIBS' to point to the
     correct thread library for your system.

          LIBS="-lpthread" ./configure ..

   * You can enable or disable the shared and static versions of
     Connector/ODBC using these options:

          --enable-shared[=yes/no]
          --disable-shared
          --enable-static[=yes/no]
          --disable-static

   * By default, all the binary distributions are built as
     non-debugging versions (configured with `--without-debug').

     To enable debugging information, build the driver from source
     distribution and use the `--with-debug' option when you run
     `configure'.

   * This option is available only for source trees that have been
     obtained from the Subversion repository. This option does not
     apply to the packaged source distributions.

     By default, the driver is built with the `--without-docs' option.
     If you would like the documentation to be built, then execute
     `configure' with:

          --with-docs


File: manual.info,  Node: connector-odbc-installation-source-unix-building,  Next: connector-odbc-installation-source-unix-shared-libraries,  Prev: connector-odbc-installation-source-unix-otheroptions,  Up: connector-odbc-installation-source-unix

20.1.3.14 Building and Compilation
..................................

To build the driver libraries, you have to just execute `make'.

     shell> make

If any errors occur, correct them and continue the build process. If
you aren't able to build, then send a detailed email to
<myodbc@lists.mysql.com> for further assistance.


File: manual.info,  Node: connector-odbc-installation-source-unix-shared-libraries,  Next: connector-odbc-installation-source-unix-installing,  Prev: connector-odbc-installation-source-unix-building,  Up: connector-odbc-installation-source-unix

20.1.3.15 Building Shared Libraries
...................................

On most platforms, MySQL does not build or support `.so' (shared)
client libraries by default.  This is based on our experience of
problems when building shared libraries.

In cases like this, you have to download the MySQL distribution and
configure it with these options:

     --without-server --enable-shared

To build shared driver libraries, you must specify the
`--enable-shared' option for `configure'. By default, `configure' does
not enable this option.

If you have configured with the `--disable-shared' option, you can
build the `.so' file from the static libraries using the following
commands:

     shell> cd mysql-connector-odbc-3.51.01
     shell> make
     shell> cd driver
     shell> CC=/usr/bin/gcc \
               $CC -bundle -flat_namespace -undefined error \
               -o .libs/libmyodbc3-3.51.01.so \
               catalog.o connect.o cursor.o dll.o error.o execute.o \
               handle.o info.o misc.o myodbc3.o options.o prepare.o \
               results.o transact.o utility.o \
               -L/usr/local/mysql/lib/mysql/ \
               -L/usr/local/iodbc/lib/ \
               -lz -lc -lmysqlclient -liodbcinst

Make sure to change `-liodbcinst' to `-lodbcinst' if you are using
`unixODBC' instead of `iODBC', and configure the library paths
accordingly.

This builds and places the `libmyodbc3-3.51.01.so' file in the `.libs'
directory. Copy this file to the Connector/ODBC library installation
directory (`/usr/local/lib' (or the `lib' directory under the
installation directory that you supplied with the `--prefix').

     shell> cd .libs
     shell> cp libmyodbc3-3.51.01.so /usr/local/lib
     shell> cd /usr/local/lib
     shell> ln -s libmyodbc3-3.51.01.so libmyodbc3.so

To build the thread-safe driver library:

     shell> CC=/usr/bin/gcc \
               $CC -bundle -flat_namespace -undefined error
               -o .libs/libmyodbc3_r-3.51.01.so
               catalog.o connect.o cursor.o dll.o error.o execute.o
               handle.o info.o misc.o myodbc3.o options.o prepare.o
               results.o transact.o utility.o
               -L/usr/local/mysql/lib/mysql/
               -L/usr/local/iodbc/lib/
               -lz -lc -lmysqlclient_r -liodbcinst


File: manual.info,  Node: connector-odbc-installation-source-unix-installing,  Next: connector-odbc-installation-source-unix-testing,  Prev: connector-odbc-installation-source-unix-shared-libraries,  Up: connector-odbc-installation-source-unix

20.1.3.16 Installing Driver Libraries
.....................................

To install the driver libraries, execute the following command:

     shell> make install

That command installs one of the following sets of libraries:

For Connector/ODBC 3.51:

   * `libmyodbc3.so'

   * `libmyodbc3-3.51.01.so', where 3.51.01 is the version of the driver

   * `libmyodbc3.a'

For thread-safe Connector/ODBC 3.51:

   * `libmyodbc3_r.so'

   * `libmyodbc3-3_r.51.01.so'

   * `libmyodbc3_r.a'

For more information on build process, refer to the `INSTALL' file that
comes with the source distribution. Note that if you are trying to use
the `make' from Sun, you may end up with errors.  On the other hand,
GNU `gmake' should work fine on all platforms.


File: manual.info,  Node: connector-odbc-installation-source-unix-testing,  Next: connector-odbc-installation-source-unix-macosx,  Prev: connector-odbc-installation-source-unix-installing,  Up: connector-odbc-installation-source-unix

20.1.3.17 Testing Connector/ODBC on Unix
........................................

To run the basic samples provided in the distribution with the
libraries that you built, use the following command:

     shell> make test

Before running the tests, create the DSN 'myodbc3' in `odbc.ini' and
set the environment variable `ODBCINI' to the correct `odbc.ini' file;
and MySQL server is running. You can find a sample `odbc.ini' with the
driver distribution.

You can even modify the `samples/run-samples' script to pass the
desired DSN, UID, and PASSWORD values as the command-line arguments to
each sample.


File: manual.info,  Node: connector-odbc-installation-source-unix-macosx,  Next: connector-odbc-installation-source-unix-hpux,  Prev: connector-odbc-installation-source-unix-testing,  Up: connector-odbc-installation-source-unix

20.1.3.18 Building Connector/ODBC from Source on Mac OS X
.........................................................

To build the driver on Mac OS X (Darwin), make use of the following
`configure' example:

     shell> ./configure --prefix=/usr/local
               --with-unixODBC=/usr/local
               --with-mysql-path=/usr/local/mysql
               --disable-shared
               --enable-gui=no
               --host=powerpc-apple

The command assumes that the `unixODBC' and MySQL are installed in the
default locations. If not, configure accordingly.

On Mac OS X, `--enable-shared' builds `.dylib' files by default. You
can build `.so' files like this:

     shell> make
     shell> cd driver
     shell> CC=/usr/bin/gcc \
               $CC -bundle -flat_namespace -undefined error
               -o .libs/libmyodbc3-3.51.01.so *.o
               -L/usr/local/mysql/lib/
               -L/usr/local/iodbc/lib
               -liodbcinst -lmysqlclient -lz -lc

To build the thread-safe driver library:

     shell> CC=/usr/bin/gcc \
               $CC -bundle -flat_namespace -undefined error
               -o .libs/libmyodbc3-3.51.01.so *.o
               -L/usr/local/mysql/lib/
               -L/usr/local/iodbc/lib
               -liodbcinst -lmysqlclienti_r -lz -lc -lpthread

Make sure to change the `-liodbcinst' to `-lodbcinst' in case of using
`unixODBC' instead of `iODBC' and configure the libraries path
accordingly.

In Apple's version of GCC, both `cc' and `gcc' are actually symbolic
links to `gcc3'.

Copy this library to the `$prefix/lib' directory and symlink to
`libmyodbc3.so'.

You can cross-check the output shared-library properties using this
command:

     shell> otool -LD .libs/libmyodbc3-3.51.01.so


File: manual.info,  Node: connector-odbc-installation-source-unix-hpux,  Next: connector-odbc-installation-source-unix-aix,  Prev: connector-odbc-installation-source-unix-macosx,  Up: connector-odbc-installation-source-unix

20.1.3.19 Building Connector/ODBC from Source on HP-UX
......................................................

To build the driver on HP-UX 10.x or 11.x, make use of the following
`configure' example:

If using `cc':

     shell> CC="cc" \
               CFLAGS="+z" \
               LDFLAGS="-Wl,+b:-Wl,+s" \
               ./configure --prefix=/usr/local
               --with-unixodbc=/usr/local
               --with-mysql-path=/usr/local/mysql/lib/mysql
               --enable-shared
               --enable-thread-safe

If using `gcc':

     shell> CC="gcc" \
               LDFLAGS="-Wl,+b:-Wl,+s" \
               ./configure --prefix=/usr/local
               --with-unixodbc=/usr/local
               --with-mysql-path=/usr/local/mysql
               --enable-shared
               --enable-thread-safe

Once the driver is built, cross-check its attributes using `chatr
.libs/libmyodbc3.sl' to determine whether you need to have set the
MySQL client library path using the `SHLIB_PATH' environment variable.
For static versions, ignore all shared-library options and run
`configure' with the `--disable-shared' option.


File: manual.info,  Node: connector-odbc-installation-source-unix-aix,  Prev: connector-odbc-installation-source-unix-hpux,  Up: connector-odbc-installation-source-unix

20.1.3.20 Building Connector/ODBC from Source on AIX
....................................................

To build the driver on AIX, make use of the following `configure'
example:

     shell> ./configure --prefix=/usr/local
               --with-unixodbc=/usr/local
               --with-mysql-path=/usr/local/mysql
               --disable-shared
               --enable-thread-safe

*Note*:

For more information about how to build and set up the static and
shared libraries across the different platforms refer to ' Using static
and shared libraries across platforms
(http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html)'.


File: manual.info,  Node: connector-odbc-installation-source-development,  Prev: connector-odbc-installation-source-unix,  Up: connector-odbc-installation

20.1.3.21 Installing Connector/ODBC from the Development Source Tree
....................................................................

*Caution*:

You should read this section only if you are interested in helping us
test our new code. If you just want to get MySQL Connector/ODBC up and
running on your system, you should use a standard release distribution.

To be able to access the Connector/ODBC source tree, you must have
Subversion installed. Subversion is freely available from
`http://subversion.tigris.org/'.

To build from the source trees, you need the following tools:

   * autoconf 2.52 (or newer)

   * automake 1.4 (or newer)

   * libtool 1.4 (or newer)

   * m4

The most recent development source tree is available from our public
Subversion trees at `http://dev.mysql.com/tech-resources/sources.html'.

To checkout out the Connector/ODBC sources, change to the directory
where you want the copy of the Connector/ODBC tree to be stored, then
use the following command:

     shell> svn co http://svn.mysql.com/svnpublic/connector-odbc3

You should now have a copy of the entire Connector/ODBC source tree in
the directory `connector-odbc3'. To build from this source tree on Unix
or Linux follow these steps:

     shell> cd connector-odbc3
     shell> aclocal
     shell> autoheader
     shell> autoconf
     shell> automake;
     shell> ./configure  # Add your favorite options here
     shell> make

For more information on how to build, refer to the `INSTALL' file
located in the same directory.  For more information on options to
`configure', see *Note
connector-odbc-installation-source-unix-configure-options::

When the build is done, run `make install' to install the
Connector/ODBC 3.51 driver on your system.

If you have gotten to the `make' stage and the distribution does not
compile, please report it to <myodbc@lists.mysql.com>.

On Windows, make use of Windows Makefiles `WIN-Makefile' and
`WIN-Makefile_debug' in building the driver.  For more information, see
*Note connector-odbc-installation-source-windows::.

After the initial checkout operation to get the source tree, you should
run `svn update' periodically update your source according to the
latest version.


File: manual.info,  Node: connector-odbc-configuration,  Next: connector-odbc-examples,  Prev: connector-odbc-installation,  Up: connector-odbc

20.1.4 Connector/ODBC Configuration
-----------------------------------

* Menu:

* connector-odbc-configuration-dsn::  Data Source Names
* connector-odbc-configuration-connection-parameters::  Connector/ODBC Connection Parameters
* connector-odbc-configuration-dsn-windows::  Configuring a Connector/ODBC DSN on Windows
* connector-odbc-configuration-dsn-macosx::  Configuring a Connector/ODBC DSN on Mac OS X
* connector-odbc-configuration-dsn-unix::  Configuring a Connector/ODBC DSN on Unix
* connector-odbc-configuration-connection-without-dsn::  Connecting Without a Predefined DSN
* connector-odbc-configuration-connection-pooling::  ODBC Connection Pooling
* connector-odbc-configuration-trace::  Getting an ODBC Trace File

Before you connect to a MySQL database using the Connector/ODBC driver
you must configure an ODBC _Data Source Name_. The DSN associates the
various configuration parameters required to communicate with a
database to a specific name. You use the DSN in an application to
communicate with the database, rather than specifying individual
parameters within the application itself. DSN information can be user
specific, system specific, or provided in a special file. ODBC data
source names are configured in different ways, depending on your
platform and ODBC driver.


File: manual.info,  Node: connector-odbc-configuration-dsn,  Next: connector-odbc-configuration-connection-parameters,  Prev: connector-odbc-configuration,  Up: connector-odbc-configuration

20.1.4.1 Data Source Names
..........................

A Data Source Name associates the configuration parameters for
communicating with a specific database. Generally a DSN consists of the
following parameters:

   * Name

   * Host Name

   * Database Name

   * Login

   * Password

In addition, different ODBC drivers, including Connector/ODBC, may
accept additional driver-specific options and parameters.

There are three types of DSN:

   * A _System DSN_ is a global DSN definition that is available to any
     user and application on a particular system. A System DSN can
     normally only be configured by a systems administrator, or by a
     user who has specific permissions that let them create System DSNs.

   * A _User DSN_ is specific to an individual user, and can be used to
     store database connectivity information that the user regularly
     uses.

   * A _File DSN_ uses a simple file to define the DSN configuration.
     File DSNs can be shared between users and machines and are
     therefore more practical when installing or deploying DSN
     information as part of an application across many machines.

DSN information is stored in different locations depending on your
platform and environment.


File: manual.info,  Node: connector-odbc-configuration-connection-parameters,  Next: connector-odbc-configuration-dsn-windows,  Prev: connector-odbc-configuration-dsn,  Up: connector-odbc-configuration

20.1.4.2 Connector/ODBC Connection Parameters
.............................................

You can specify the parameters in the following tables for
Connector/ODBC when configuring a DSN. Users on Windows can use the
Options and Advanced panels when configuring a DSN to set these
parameters; see the table for information on which options relate to
which fields and checkboxes. On Unix and Mac OS X, use the parameter
name and value as the keyword/value pair in the DSN configuration.
Alternatively, you can set these parameters within the
`InConnectionString' argument in the `SQLDriverConnect()' call.

Parameter   Default Value  Comment
`user'      ODBC           The user name used to connect to MySQL.
`uid'       ODBC           Synonymous with `user'. Added in 3.51.16.
`server'    `localhost'    The host name of the MySQL server.
`database'                 The default database.
`option'    0              Options that specify how Connector/ODBC should
                           work. See below.
`port'      3306           The TCP/IP port to use if `server' is not
                           `localhost'.
`initstmt'                 Initial statement. A statement to execute when
                           connecting to MySQL. In version 3.51 the
                           parameter is called `stmt'. Note, the driver
                           supports the initial statement being executed
                           only at the time of the initial connection.
`password'                 The password for the `user' account on
                           `server'.
`pwd'                      Synonymous with `password'. Added in 3.51.16.
`socket'                   The Unix socket file or Windows named pipe to
                           connect to if `server' is `localhost'.
`sslca'                    The path to a file with a list of trust SSL
                           CAs. Added in 3.51.16.
`sslcapath'                The path to a directory that contains trusted
                           SSL CA certificates in PEM format. Added in
                           3.51.16.
`sslcert'                  The name of the SSL certificate file to use
                           for establishing a secure connection. Added in
                           3.51.16.
`sslcipher'                A list of allowable ciphers to use for SSL
                           encryption. The cipher list has the same
                           format as the `openssl ciphers' command Added
                           in 3.51.16.
`sslkey'                   The name of the SSL key file to use for
                           establishing a secure connection. Added in
                           3.51.16.
`charset'                  The character set to use for the connection.
                           Added in 3.51.17.
`sslverify'                If set to 1, the SSL certificate will be
                           verified when used with the MySQL connection.
                           If not set, then the default behaviour is to
                           ignore SSL certificate verification.
`readtimeout'               The timeout in seconds for attempts to read
                           from the server. Each attempt uses this
                           timeout value and there are retries if
                           necessary, so the total effective timeout
                           value is three times the option value. You can
                           set the value so that a lost connection can be
                           detected earlier than the TCP/IP
                           `Close_Wait_Timeout' value of 10 minutes. This
                           option works only for TCP/IP connections, and
                           only for Windows prior to MySQL 5.1.12.
                           Corresponds to the `MYSQL_OPT_READ_TIMEOUT'
                           option of the MySQL Client Library. This
                           option was added in Connector/ODBC 3.51.27.
`writetimeout'               The timeout in seconds for attempts to write
                           to the server. Each attempt uses this timeout
                           value and there are `net_retry_count' retries
                           if necessary, so the total effective timeout
                           value is `net_retry_count' times the option
                           value. This option works only for TCP/IP
                           connections, and only for Windows prior to
                           MySQL 5.1.12. Corresponds to the
                           `MYSQL_OPT_WRITE_TIMEOUT' option of the MySQL
                           Client Library. This option was added in
                           Connector/ODBC 3.51.27.

*Note*:

The SSL configuration parameters can also be automatically loaded from
a `my.ini' or `my.cnf' file.

The `option' argument is used to tell Connector/ODBC that the client
isn't 100% ODBC compliant. On Windows, you normally select options by
toggling the checkboxes in the connection screen, but you can also
select them in the `option' argument. The following options are listed
in the order in which they appear in the Connector/ODBC connect screen.

*Value* *Flagname*     *GUI Option*   *Description*
1       `FLAG_FIELD_LENGTH'Do not         The client cannot handle that
                       Optimize       Connector/ODBC returns the real
                       Column Width   width of a column. This option was
                                      removed in 3.51.18.
2       `FLAG_FOUND_ROWS'Return         The client cannot handle that MySQL
                       Matching Rows  returns the true value of affected
                                      rows. If this flag is set, MySQL
                                      returns `found rows' instead. You
                                      must have MySQL 3.21.14 or newer to
                                      get this to work.
4       `FLAG_DEBUG'   Trace Driver   Make a debug log in `C:\myodbc.log'
                       Calls To       on Windows, or `/tmp/myodbc.log' on
                       myodbc.log     Unix variants.  This option was
                                      removed in Connector/ODBC 3.51.18.
8       `FLAG_BIG_PACKETS'Allow Big      Do not set any packet limit for
                       Results        results and bind parameters. Without
                                      this option, parameter binding will
                                      be truncated to 255 characters.
16      `FLAG_NO_PROMPT'Do not Prompt  Do not prompt for questions even if
                       Upon Connect   driver would like to prompt.
32      `FLAG_DYNAMIC_CURSOR'Enable         Enable or disable the dynamic
                       Dynamic Cursor cursor support.
64      `FLAG_NO_SCHEMA'Ignore # in    Ignore use of database name in
                       Table Name     DB_NAME.TBL_NAME.COL_NAME.
128     `FLAG_NO_DEFAULT_CURSOR'User Manager   Force use of ODBC manager cursors
                       Cursors        (experimental).
256     `FLAG_NO_LOCALE'Do not Use     Disable the use of extended fetch
                       Set Locale     (experimental).
512     `FLAG_PAD_SPACE'Pad Char To    Pad *Note `CHAR': char. columns to
                       Full Length    full column length.
1024    `FLAG_FULL_COLUMN_NAMES'Return Table   `SQLDescribeCol()' returns fully
                       Names for      qualified column names.
                       SQLDescribeCol 
2048    `FLAG_COMPRESSED_PROTO'Use            Use the compressed client/server
                       Compressed     protocol.
                       Protocol       
4096    `FLAG_IGNORE_SPACE'Ignore Space   Tell server to ignore space after
                       After          function name and before ``(''
                       Function Names (needed by PowerBuilder). This
                                      makes all function names keywords.
8192    `FLAG_NAMED_PIPE'Force Use of   Connect with named pipes to a *Note
                       Named Pipes    `mysqld': mysqld. server running on
                                      NT.
16384   `FLAG_NO_BIGINT'Change BIGINT  Change *Note `BIGINT':
                       Columns to Int numeric-types. columns to *Note
                                      `INT': numeric-types. columns (some
                                      applications cannot handle *Note
                                      `BIGINT': numeric-types.).
32768   `FLAG_NO_CATALOG'No Catalog     Forces results from the catalog
                                      functions, such as `SQLTables', to
                                      always return `NULL' and the driver
                                      to report that catalogs are not
                                      supported.
65536   `FLAG_USE_MYCNF'Read Options   Read parameters from the `[client]'
                       From `my.cnf'  and `[odbc]' groups from `my.cnf'.
131072  `FLAG_SAFE'    Safe           Add some extra safety checks.
262144  `FLAG_NO_TRANSACTIONS'Disable        Disable transactions.
                       transactions   
524288  `FLAG_LOG_QUERY'Save queries   Enable query logging to
                       to             `c:\myodbc.sql'(`/tmp/myodbc.sql')
                       `myodbc.sql'   file. (Enabled only in debug mode.)
1048576 `FLAG_NO_CACHE'Do not Cache   Do not cache the results locally in
                       Result         the driver, instead read from server
                       (forward only  (*Note `mysql_use_result()':
                       cursors)       mysql-use-result.).  This works
                                      only for forward-only cursors. This
                                      option is very important in dealing
                                      with large tables when you do not
                                      want the driver to cache the entire
                                      result set.
2097152 `FLAG_FORWARD_CURSOR'Force Use Of   Force the use of `Forward-only'
                       Forward Only   cursor type. In case of
                       Cursors        applications setting the default
                                      static/dynamic cursor type, and one
                                      wants the driver to use non-cache
                                      result sets, then this option
                                      ensures the forward-only cursor
                                      behavior.
4194304 `FLAG_AUTO_RECONNECT'Enable         Enables auto-reconnection
                       auto-reconnect.functionality. You should not use
                                      this option with transactions,
                                      since a auto reconnection during a
                                      incomplete transaction may cause
                                      corruption. Note that an
                                      auto-reconnected connection will
                                      not inherit the same settings and
                                      environment as the original. This
                                      option was added in Connector/ODBC
                                      3.51.13.
8388608 `FLAG_AUTO_IS_NULL'Flag Auto Is   When `FLAG_AUTO_IS_NULL' is set, the
                       Null           driver does not change the default
                                      value of `sql_auto_is_null',
                                      leaving it at 1, so you get the
                                      MySQL default, not the SQL standard
                                      behavior.
                                      
                                      When `FLAG_AUTO_IS_NULL' is not set,
                                      the driver changes the default
                                      value of `SQL_AUTO_IS_NULL' to 0
                                      after connecting, so you get the
                                      SQL standard, not the MySQL default
                                      behaviour.
                                      
                                      Thus, omitting the flag disables
                                      the compatibility option and forces
                                      SQL standard behaviour.
                                      
                                      See `IS NULL'. This option was
                                      added in Connector/ODBC 3.51.13.
16777216`FLAG_ZERO_DATE_TO_MIN'Flag Zero      Translates zero dates
                       Date to Min    (`XXXX-00-00') into the minimum
                                      date values supported by ODBC,
                                      `XXXX-01-01'. This resolves an issue
                                      where some statements will not work
                                      because the date returned and the
                                      minimum ODBC date value are
                                      incompatible. This option was added
                                      in Connector/ODBC 3.51.17.
33554432`FLAG_MIN_DATE_TO_ZERO'Flag Min Date  Translates the minimum ODBC date
                       to Zero        value (`XXXX-01-01') to the zero
                                      date format supported by MySQL
                                      (`XXXX-00-00'). This resolves an
                                      issue where some statements will
                                      not work because the date returned
                                      and the minimum ODBC date value are
                                      incompatible. This option was added
                                      in Connector/ODBC 3.51.17.
67108864`FLAG_MULTI_STATEMENTS'Allow          Enables support for batched
                       multiple       statements. This option was added in
                       statements     Connector/ODBC 3.51.18.
134217728`FLAG_COLUMN_SIZE_S32'Limit column   Limits the column size to a signed
                       size to        32-bit value to prevent problems
                       32-bit value   with larger column sizes in
                                      applications that do not support
                                      them. This option is automatically
                                      enabled when working with ADO
                                      applications. This option was added
                                      in Connector/ODBC 3.51.22.
268435456`FLAG_NO_BINARY_RESULT'Always handle  When set this option disables
                       binary         charset 63 for columns with an empty
                       function       `org_table'. This option was added
                       results as     in Connector/ODBC 3.51.26.
                       character data 

To select multiple options, add together their values. For example,
setting `option' to 12 (4+8) gives you debugging without packet limits.

The following table shows some recommended `option' values for various
configurations.

*Configuration*                                               *Option
                                                              Value*
Microsoft Access, Visual Basic                                3
Driver trace generation (Debug mode)                          4
Microsoft Access (with improved DELETE queries)               35
Large tables with too many rows                               2049
Sybase PowerBuilder                                           135168
Query log generation (Debug mode)                             524288
Generate driver trace as well as query log (Debug mode)       524292
Large tables with no-cache results                            3145731


File: manual.info,  Node: connector-odbc-configuration-dsn-windows,  Next: connector-odbc-configuration-dsn-macosx,  Prev: connector-odbc-configuration-connection-parameters,  Up: connector-odbc-configuration

20.1.4.3 Configuring a Connector/ODBC DSN on Windows
....................................................

* Menu:

* connector-odbc-configuration-dsn-windows-3-51::  Configuring a Connector/ODBC 3.51 DSN on Windows
* connector-odbc-configuration-dsn-windows-5-1::  Configuring a Connector/ODBC 5.1 DSN on Windows
* connector-odbc-configuration-dsn-windows-problems::  Errors and Debugging

The `ODBC Data Source Administrator' within Windows enables you to
create DSNs, check driver installation and configure ODBC systems such
as tracing (used for debugging) and connection pooling.

Different editions and versions of Windows store the `ODBC Data Source
Administrator' in different locations depending on the version of
Windows that you are using.

To open the `ODBC Data Source Administrator' in Windows Server 2003:

*Tip*:

Because it is possible to create DSN using either the 32-bit or 64-bit
driver, but using the same DNS identifier, it is advisable to include
the driver being used within the DSN identifier. This will help you to
identify the DSN when using it from applications such as Excel that are
only compatible with the 32-bit driver. For example, you might add
`Using32bitCODBC' to the DSN identifier for the 32-bit interface and
`Using64bitCODBC' for those using the 64-bit Connector/ODBC driver.

  1. On the `Start' menu, choose `Administrative Tools', and then click
     `Data Sources (ODBC)'.

To open the `ODBC Data Source Administrator' in Windows 2000 Server or
Windows 2000 Professional:

  1. On the `Start' menu, choose `Settings', and then click `Control
     Panel'.

  2. In `Control Panel', click `Administrative Tools'.

  3. In `Administrative Tools', click `Data Sources (ODBC)'.

To open the `ODBC Data Source Administrator' on Windows XP:

  1. On the `Start' menu, click `Control Panel'.

  2. In the `Control Panel' when in `Category View' click `Performance
     and Maintenance' and then click `Administrative Tools.'. If you
     are viewing the `Control Panel' in `Classic View', click
     `Administrative Tools'.

  3. In `Administrative Tools', click `Data Sources (ODBC)'.

Irrespective of your Windows version, you should be presented the `ODBC
Data Source Administrator' window:

`ODBC Data Source Administrator' Dialog

Within Windows XP, you can add the `Administrative Tools' folder to
your `Start' menu to make it easier to locate the ODBC Data Source
Administrator.  To do this:

  1. Right click on the `Start' menu.

  2. Select `Properties'.

  3. Click `Customize...'.

  4. Select the `Advanced' tab.

  5. Within `Start menu items', within the `System Administrative
     Tools' section, select `Display on the All Programs menu'.

Within both Windows Server 2003 and Windows XP you may want to
permanently add the `ODBC Data Source Administrator' to your `Start'
menu. To do this, locate the `Data Sources (ODBC)' icon using the
methods shown, then right-click on the icon and then choose `Pin to
Start Menu'.

The interfaces for the 3.51 and 5.1 versions of the Connector/ODBC
driver are different, although the fields and information that you need
to enter remain the same.

To configure a DSN using Connector/ODBC 3.51.x or Connector/ODBC 5.1.0,
see *Note connector-odbc-configuration-dsn-windows-3-51::.

To configure a DSN using Connector/ODBC 5.1.1 or later, see *Note
connector-odbc-configuration-dsn-windows-5-1::.


File: manual.info,  Node: connector-odbc-configuration-dsn-windows-3-51,  Next: connector-odbc-configuration-dsn-windows-5-1,  Prev: connector-odbc-configuration-dsn-windows,  Up: connector-odbc-configuration-dsn-windows

20.1.4.4 Configuring a Connector/ODBC 3.51 DSN on Windows
.........................................................

To add and configure a new Connector/ODBC data source on Windows, use
the `ODBC Data Source Administrator':

  1. Open the `ODBC Data Source Administrator'.

  2. To create a System DSN (which will be available to all users) ,
     select the `System DSN' tab. To create a User DSN, which will be
     unique only to the current user, click the `Add...' button.

  3. You will need to select the ODBC driver for this DSN.

     `MySQL ODBC Driver Selection' Dialog

     Select `MySQL ODBC 3.51 Driver', then click `Finish'.

  4. You now need to configure the specific fields for the DSN you are
     creating through the `Add Data Source Name' dialog.

     `Add Data Source Name' Dialog for Connector/ODBC 3.51.x

     In the `Data Source Name' box, enter the name of the data source
     you want to access. It can be any valid name that you choose.

  5. In the `Description' box, enter some text to help identify the
     connection.

  6. In the `Server' field, enter the name of the MySQL server host
     that you want to access. By default, it is `localhost'.

  7. In the `User' field, enter the user name to use for this
     connection.

  8. In the `Password' field, enter the corresponding password for this
     connection.

  9. The `Database' pop-up should automatically populate with the list
     of databases that the user has permissions to access.

 10. Click `OK' to save the DSN.

A completed DSN configuration may look like this:

Sample`MySQL ODBC DSN Configuration' Dialog

You can verify the connection using the parameters you have entered by
clicking the `Test' button. If the connection could be made
successfully, you will be notified with a `Success; connection was
made!' dialog.

If the connection failed, you can obtain more information on the test
and why it may have failed by clicking the `Diagnostics...' button to
show additional error messages.

You can configure a number of options for a specific DSN by using
either the `Connect Options' or `Advanced' tabs in the DSN configuration
dialog.

Connector/ODBC Connect Options Dialog

The three options you can configure are:

   * `Port' sets the TCP/IP port number to use when communicating with
     MySQL. Communication with MySQL uses port 3306 by default. If your
     server is configured to use a different TCP/IP port, you must
     specify that port number here.

   * `Socket' sets the name or location of a specific socket or Windows
     pipe to use when communicating with MySQL.

   * `Initial Statement' defines an SQL statement that will be executed
     when the connection to MySQL is opened. You can use this to set
     MySQL options for your connection, such as disabling autocommit.

   * `Character Set' is a pop-up list from which you can select the
     default character set to be used with this connection. The
     Character Set option was added in 3.5.17.

The `Advanced' tab enables you to configure Connector/ODBC connection
parameters. Refer to *Note
connector-odbc-configuration-connection-parameters::, for information
about the meaning of these options.

Connector/ODBC Connection Advanced Dialog


File: manual.info,  Node: connector-odbc-configuration-dsn-windows-5-1,  Next: connector-odbc-configuration-dsn-windows-problems,  Prev: connector-odbc-configuration-dsn-windows-3-51,  Up: connector-odbc-configuration-dsn-windows

20.1.4.5 Configuring a Connector/ODBC 5.1 DSN on Windows
........................................................

The DSN configuration when using Connector/ODBC 5.1.1 and later has a
slightly different layout. Also, due to the native Unicode support
within Connector/ODBC 5.1, you no longer need to specify the initial
character set to be used with your connection.

To configure a DSN using the Connector/ODBC 5.1.1 or later driver:

  1. Open the `ODBC Data Source Administrator'.

  2. To create a System DSN (which will be available to all users) ,
     select the `System DSN' tab.  To create a User DSN, which will be
     unique only to the current user, click the `Add...' button.

  3. You will need to select the ODBC driver for this DSN.

     `MySQL ODBC Driver Selection' Dialog

     Select `MySQL ODBC 5.1 Driver', then click `Finish'.

  4. You now need to configure the specific fields for the DSN you are
     creating through the `Connection Parameters' dialog.

     `Add Data Source Name' Dialog for Connector/ODBC 5.1

     In the `Data Source Name' box, enter the name of the data source
     you want to access. It can be any valid name that you choose.

  5. In the `Description' box, enter some text to help identify the
     connection.

  6. In the `Server' field, enter the name of the MySQL server host
     that you want to access. By default, it is `localhost'.

  7. In the `User' field, enter the user name to use for this
     connection.

  8. In the `Password' field, enter the corresponding password for this
     connection.

  9. The `Database' pop-up should automatically populate with the list
     of databases that the user has permissions to access.

 10. To communicate over a different TCP/IP port than the default
     (3306), change the value of the `Port'.

 11. Click `OK' to save the DSN.

You can verify the connection using the parameters you have entered by
clicking the `Test' button. If the connection could be made
successfully, you will be notified with a `Success; connection was
made!' dialog.

You can configure a number of options for a specific DSN by using the
`Details' button.

Connector/ODBC Connect Options Dialog

The `Details' button opens a tabbed display which allows you to set
additional options:

   * `Flags 1', `Flags 2', and `Flags 3' enable you to select the
     additional flags for the DSN connection. For more information on
     these flags, see *Note
     connector-odbc-configuration-connection-parameters::.

   * `Debug' allows you to enable ODBC debugging to record the queries
     you execute through the DSN to the `myodbc.sql' file. For more
     information, see *Note connector-odbc-configuration-trace::.

   * `SSL Settings' configures the additional options required for
     using the Secure Sockets Layer (SSL) when communicating with MySQL
     server. Note that you must have enabled SSL and configured the
     MySQL server with suitable certificates to communicate over SSL.

     Connector/ODBC 5.1 SSL Configuration

The `Advanced' tab enables you to configure Connector/ODBC connection
parameters. Refer to *Note
connector-odbc-configuration-connection-parameters::, for information
about the meaning of these options.


File: manual.info,  Node: connector-odbc-configuration-dsn-windows-problems,  Prev: connector-odbc-configuration-dsn-windows-5-1,  Up: connector-odbc-configuration-dsn-windows

20.1.4.6 Errors and Debugging
.............................

This section answers Connector/ODBC connection-related questions.

   * *While configuring a Connector/ODBC DSN, a `Could Not Load
     Translator or Setup Library' error occurs*

     For more information, refer to MS KnowledgeBase Article(Q260558)
     (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q260558).
     Also, make sure you have the latest valid `ctl3d32.dll' in your
     system directory.

   * On Windows, the default `myodbc3.dll' is compiled for optimal
     performance. If you want to debug Connector/ODBC 3.51 (for
     example, to enable tracing), you should instead use
     `myodbc3d.dll'. To install this file, copy `myodbc3d.dll' over the
     installed `myodbc3.dll' file.  Make sure to revert back to the
     release version of the driver DLL once you are done with the
     debugging because the debug version may cause performance issues.
     Note that the `myodbc3d.dll' isn't included in Connector/ODBC
     3.51.07 through 3.51.11. If you are using one of these versions,
     you should copy that DLL from a previous version (for example,
     3.51.06).


File: manual.info,  Node: connector-odbc-configuration-dsn-macosx,  Next: connector-odbc-configuration-dsn-unix,  Prev: connector-odbc-configuration-dsn-windows,  Up: connector-odbc-configuration

20.1.4.7 Configuring a Connector/ODBC DSN on Mac OS X
.....................................................

To configure a DSN on Mac OS X you can either use the `myodbc3i'
utility, edit the `odbc.ini' file within the `Library/ODBC' directory
of the user or the should use the ODBC Administrator. If you have Mac
OS X 10.2 or earlier, refer to *Note
connector-odbc-configuration-dsn-unix::. Select whether you want to
create a User DSN or a System DSN. If you want to add a System DSN, you
may need to authenticate with the system. You must click the padlock
and enter a user and password with administrator privileges.

For correct operation of ODBC Administrator, you should ensure that the
`/Library/ODBC/odbc.ini' file used to set up ODBC connectivity and DSNs
are writable by the `admin' group. If this file is not writable by this
group then the ODBC Administrator may fail, or may appear to have
worked but not generated the correct entry.

*Warning*:

There are known issues with the OS X ODBC Administrator and
Connector/ODBC that may prevent you from creating a DSN using this
method. In this case you should use the command-line or edit the
`odbc.ini' file directly. Note that existing DSNs or those that you
create via the `myodbc3i' or `myodbc-installer'tool can still be checked
and edited using ODBC Administrator.

To create a DSN using the `myodbc3i' utility, you need only specify the
DSN type and the DSN connection string. For example:

     shell> myodbc3i -a -s -t"DSN=mydb;DRIVER=MySQL ODBC 3.51 Driver;SERVER=mysql;USER=username;PASSWORD=pass"

To use ODBC Administrator:

  1. Open the ODBC Administrator from the `Utilities' folder in the
     `Applications' folder.

     `ODBC Administrator Main Panel' Dialog

  2. On the User DSN or System DSN panel, click `Add.'

  3. Select the Connector/ODBC driver and click `OK'.

  4. You will be presented with the `Data Source Name' dialog. Enter
     The `Data Source Name' and an optional `Description' for the DSN.

     `ODBC Administrator Add DSN' Dialog

  5. Click `Add' to add a new keyword/value pair to the panel. You
     should configure at least four pairs to specify the `server',
     `username', `password' and `database' connection parameters. See
     *Note connector-odbc-configuration-connection-parameters::.

  6. Click `OK' to add the DSN to the list of configured data source
     names.

A completed DSN configuration may look like this:

`ODBC Administrator Sample DSN' Dialog

You can configure additional ODBC options to your DSN by adding further
keyword/value pairs and setting the corresponding values. See *Note
connector-odbc-configuration-connection-parameters::.


File: manual.info,  Node: connector-odbc-configuration-dsn-unix,  Next: connector-odbc-configuration-connection-without-dsn,  Prev: connector-odbc-configuration-dsn-macosx,  Up: connector-odbc-configuration

20.1.4.8 Configuring a Connector/ODBC DSN on Unix
.................................................

On `Unix', you configure DSN entries directly in the `odbc.ini' file.
Here is a typical `odbc.ini' file that configures `myodbc3' as the DSN
name for Connector/ODBC 3.51:

     ;
     ;  odbc.ini configuration for Connector/ODBC and Connector/ODBC 3.51 drivers
     ;

     [ODBC Data Sources]
     myodbc3     = MyODBC 3.51 Driver DSN

     [myodbc3]
     Driver       = /usr/local/lib/libmyodbc3.so
     Description  = Connector/ODBC 3.51 Driver DSN
     SERVER       = localhost
     PORT         =
     USER         = root
     Password     =
     Database     = test
     OPTION       = 3
     SOCKET       =

     [Default]
     Driver       = /usr/local/lib/libmyodbc3.so
     Description  = Connector/ODBC 3.51 Driver DSN
     SERVER       = localhost
     PORT         =
     USER         = root
     Password     =
     Database     = test
     OPTION       = 3
     SOCKET       =

Refer to the *Note connector-odbc-configuration-connection-parameters::,
for the list of connection parameters that can be supplied.

*Note*:

If you are using `unixODBC', you can use the following tools to set up
the DSN:

   * ODBCConfig GUI tool(HOWTO: ODBCConfig
     (http://www.unixodbc.org/config.html))

   * odbcinst

In some cases when using `unixODBC', you might get this error:

     Data source name not found and no default driver specified

If this happens, make sure the `ODBCINI' and `ODBCSYSINI' environment
variables are pointing to the right `odbc.ini' file. For example, if
your `odbc.ini' file is located in `/usr/local/etc', set the environment
variables like this:

     export ODBCINI=/usr/local/etc/odbc.ini
     export ODBCSYSINI=/usr/local/etc


File: manual.info,  Node: connector-odbc-configuration-connection-without-dsn,  Next: connector-odbc-configuration-connection-pooling,  Prev: connector-odbc-configuration-dsn-unix,  Up: connector-odbc-configuration

20.1.4.9 Connecting Without a Predefined DSN
............................................

You can connect to the MySQL server using SQLDriverConnect, by
specifying the `DRIVER' name field. Here are the connection strings for
Connector/ODBC using DSN-Less connections:

*For Connector/ODBC 3.51:*

     ConnectionString = "DRIVER={MySQL ODBC 3.51 Driver};\
                        SERVER=localhost;\
                        DATABASE=test;\
                        USER=venu;\
                        PASSWORD=venu;\
                        OPTION=3;"

If your programming language converts backslash followed by whitespace
to a space, it is preferable to specify the connection string as a
single long string, or to use a concatenation of multiple strings that
does not add spaces in between. For example:

     ConnectionString = "DRIVER={MySQL ODBC 3.51 Driver};"
                        "SERVER=localhost;"
                        "DATABASE=test;"
                        "USER=venu;"
                        "PASSWORD=venu;"
                        "OPTION=3;"

Note

Note that on Mac OS X you may need to specify the full path to the
Connector/ODBC driver library.

Refer to the *Note connector-odbc-configuration-connection-parameters::,
for the list of connection parameters that can be supplied.


File: manual.info,  Node: connector-odbc-configuration-connection-pooling,  Next: connector-odbc-configuration-trace,  Prev: connector-odbc-configuration-connection-without-dsn,  Up: connector-odbc-configuration

20.1.4.10 ODBC Connection Pooling
.................................

Connection pooling enables the ODBC driver to re-use existing
connections to a given database from a pool of connections, instead of
opening a new connection each time the database is accessed. By
enabling connection pooling you can improve the overall performance of
your application by lowering the time taken to open a connection to a
database in the connection pool.

For more information about connection pooling:
`http://support.microsoft.com/default.aspx?scid=kb;EN-US;q169470'.


File: manual.info,  Node: connector-odbc-configuration-trace,  Prev: connector-odbc-configuration-connection-pooling,  Up: connector-odbc-configuration

20.1.4.11 Getting an ODBC Trace File
....................................

* Menu:

* connector-odbc-configuration-trace-windows::  Enabling ODBC Tracing on Windows
* connector-odbc-configuration-trace-macosx::  Enabling ODBC Tracing on Mac OS X
* connector-odbc-configuration-trace-unix::  Enabling ODBC Tracing on Unix
* connector-odbc-configuration-trace-log::  Enabling a Connector/ODBC Log

If you encounter difficulties or problems with Connector/ODBC, you
should start by making a log file from the `ODBC Manager' and
Connector/ODBC. This is called _tracing_, and is enabled through the
ODBC Manager. The procedure for this differs for Windows, Mac OS X and
Unix.


File: manual.info,  Node: connector-odbc-configuration-trace-windows,  Next: connector-odbc-configuration-trace-macosx,  Prev: connector-odbc-configuration-trace,  Up: connector-odbc-configuration-trace

20.1.4.12 Enabling ODBC Tracing on Windows
..........................................

To enable the trace option on Windows:

  1. The `Tracing' tab of the ODBC Data Source Administrator dialog box
     enables you to configure the way ODBC function calls are traced.

     ODBC Data Source Administrator Tracing Dialog

  2. When you activate tracing from the `Tracing' tab, the `Driver
     Manager' logs all ODBC function calls for all subsequently run
     applications.

  3. ODBC function calls from applications running before tracing is
     activated are not logged. ODBC function calls are recorded in a
     log file you specify.

  4. Tracing ceases only after you click `Stop Tracing Now'. Remember
     that while tracing is on, the log file continues to increase in
     size and that tracing affects the performance of all your ODBC
     applications.


File: manual.info,  Node: connector-odbc-configuration-trace-macosx,  Next: connector-odbc-configuration-trace-unix,  Prev: connector-odbc-configuration-trace-windows,  Up: connector-odbc-configuration-trace

20.1.4.13 Enabling ODBC Tracing on Mac OS X
...........................................

To enable the trace option on Mac OS X 10.3 or later you should use the
`Tracing' tab within ODBC Administrator .

  1. Open the ODBC Administrator.

  2. Select the `Tracing' tab.

     ODBC Administrator Tracing Dialog

  3. Select the `Enable Tracing' checkbox.

  4. Enter the location where you want to save the Tracing log.  If you
     want to append information to an existing log file, click the
     `Choose...' button.


File: manual.info,  Node: connector-odbc-configuration-trace-unix,  Next: connector-odbc-configuration-trace-log,  Prev: connector-odbc-configuration-trace-macosx,  Up: connector-odbc-configuration-trace

20.1.4.14 Enabling ODBC Tracing on Unix
.......................................

To enable the trace option on Mac OS X 10.2 (or earlier) or Unix you
must add the `trace' option to the ODBC configuration:

  1. On Unix, you need to explicitly set the `Trace' option in the
     `ODBC.INI' file.

     Set the tracing `ON' or `OFF' by using `TraceFile' and `Trace'
     parameters in `odbc.ini' as shown below:

          TraceFile  = /tmp/odbc.trace
          Trace      = 1

     `TraceFile' specifies the name and full path of the trace file and
     `Trace' is set to `ON' or `OFF'. You can also use `1' or `YES' for
     `ON' and `0' or `NO' for `OFF'. If you are using `ODBCConfig' from
     `unixODBC', then follow the instructions for tracing `unixODBC'
     calls at HOWTO-ODBCConfig (http://www.unixodbc.org/config.html).


File: manual.info,  Node: connector-odbc-configuration-trace-log,  Prev: connector-odbc-configuration-trace-unix,  Up: connector-odbc-configuration-trace

20.1.4.15 Enabling a Connector/ODBC Log
.......................................

To generate a Connector/ODBC log, do the following:

  1. Within Windows, enable the `Trace Connector/ODBC' option flag in
     the Connector/ODBC connect/configure screen. The log is written to
     file `C:\myodbc.log'. If the trace option is not remembered when
     you are going back to the above screen, it means that you are not
     using the `myodbcd.dll' driver, see *Note
     connector-odbc-configuration-dsn-windows-problems::.

     On Mac OS X, Unix, or if you are using DSN-Less connection, then
     you need to supply `OPTION=4' in the connection string or set the
     corresponding keyword/value pair in the DSN.

  2. Start your application and try to get it to fail. Then check the
     Connector/ODBC trace file to find out what could be wrong.

If you need help determining what is wrong, see *Note
connector-odbc-support-community::.


File: manual.info,  Node: connector-odbc-examples,  Next: connector-odbc-reference,  Prev: connector-odbc-configuration,  Up: connector-odbc

20.1.5 Connector/ODBC Examples
------------------------------

* Menu:

* connector-odbc-examples-overview::  Basic Connector/ODBC Application Steps
* connector-odbc-examples-walkthrough::  Step-by-step Guide to Connecting to a MySQL Database through Connector/ODBC
* connector-odbc-examples-tools::  Connector/ODBC and Third-Party ODBC Tools
* connector-odbc-examples-tools-with-access::  Using Connector/ODBC with Microsoft Access
* connector-odbc-examples-tools-with-wordexcel::  Using Connector/ODBC with Microsoft Word or Excel
* connector-odbc-examples-tools-with-crystalreports::  Using Connector/ODBC with Crystal Reports
* connector-odbc-examples-programming::  Connector/ODBC Programming

Once you have configured a DSN to provide access to a database, how you
access and use that connection is dependent on the application or
programming language. As ODBC is a standardized interface, any
application or language that supports ODBC can use the DSN and connect
to the configured database.


File: manual.info,  Node: connector-odbc-examples-overview,  Next: connector-odbc-examples-walkthrough,  Prev: connector-odbc-examples,  Up: connector-odbc-examples

20.1.5.1 Basic Connector/ODBC Application Steps
...............................................

Interacting with a MySQL server from an applications using the
Connector/ODBC typically involves the following operations:

   * Configure the Connector/ODBC DSN

   * Connect to MySQL server

   * Initialization operations

   * Execute SQL statements

   * Retrieve results

   * Perform Transactions

   * Disconnect from the server

Most applications use some variation of these steps. The basic
application steps are shown in the following diagram:

Connector/ODBC Programming Flowchart


File: manual.info,  Node: connector-odbc-examples-walkthrough,  Next: connector-odbc-examples-tools,  Prev: connector-odbc-examples-overview,  Up: connector-odbc-examples

20.1.5.2 Step-by-step Guide to Connecting to a MySQL Database through Connector/ODBC
....................................................................................

A typical installation situation where you would install Connector/ODBC
is when you want to access a database on a Linux or Unix host from a
Windows machine.

As an example of the process required to set up access between two
machines, the steps below take you through the basic steps.  These
instructions assume that you want to connect to system ALPHA from
system BETA with a user name and password of `myuser' and `mypassword'.

On system ALPHA (the MySQL server) follow these steps:

  1. Start the MySQL server.

  2. Use *Note `GRANT': grant. to set up an account with a user name of
     `myuser' that can connect from system BETA using a password of
     `myuser' to the database `test':

          GRANT ALL ON test.* to 'myuser'@'BETA' IDENTIFIED BY 'mypassword';

     For more information about MySQL privileges, refer to *Note
     user-account-management::.

On system BETA (the Connector/ODBC client), follow these steps:

  1. Configure a Connector/ODBC DSN using parameters that match the
     server, database and authentication information that you have just
     configured on system ALPHA.

     *Parameter**Value*       *Comment*
     DSN        remote_test   A name to identify the connection.
     SERVER     ALPHA         The address of the remote server.
     DATABASE   test          The name of the default database.
     USER       myuser        The user name configured for access to this
                              database.
     PASSWORD   mypassword    The password for `myuser'.

  2. Using an ODBC-capable application, such as Microsoft Office,
     connect to the MySQL server using the DSN you have just created.
     If the connection fails, use tracing to examine the connection
     process. See *Note connector-odbc-configuration-trace::, for more
     information.


File: manual.info,  Node: connector-odbc-examples-tools,  Next: connector-odbc-examples-tools-with-access,  Prev: connector-odbc-examples-walkthrough,  Up: connector-odbc-examples

20.1.5.3 Connector/ODBC and Third-Party ODBC Tools
..................................................

Once you have configured your Connector/ODBC DSN, you can access your
MySQL database through any application that supports the ODBC
interface, including programming languages and third-party
applications. This section contains guides and help on using
Connector/ODBC with various ODBC-compatible tools and applications,
including Microsoft Word, Microsoft Excel and Adobe/Macromedia
ColdFusion.

Connector/ODBC has been tested with the following applications.

*Publisher*        *Application*      *Notes*
Adobe              ColdFusion         Formerly Macromedia ColdFusion
Borland            C++ Builder        
                   Builder 4          
                   Delphi             
Business Objects   Crystal Reports    
Claris             Filemaker Pro      
Corel              Paradox            
Computer           Visual Objects     Also known as CAVO
Associates                            
                   AllFusion ERwin    
                   Data Modeler       
Gupta              Team Developer     Previously known as Centura Team
                                      Developer; Gupta SQL/Windows
Gensym             G2-ODBC Bridge     
Inline             iHTML              
Lotus              Notes              Versions 4.5 and 4.6
Microsoft          Access             
                   Excel              
                   Visio Enterprise   
                   Visual C++         
                   Visual Basic       
                   ODBC.NET           Using C#, Visual Basic, C++
                   FoxPro             
                   Visual Interdev    
OpenOffice.org     OpenOffice.org     
Perl               DBD::ODBC          
Pervasive Software DataJunction       
Sambar             Sambar Server      
Technologies                          
SPSS               SPSS               
SoftVelocity       Clarion            
SQLExpress         SQLExpress for     
                   Xbase++            
Sun                StarOffice         
SunSystems         Vision             
Sybase             PowerBuilder       
                   PowerDesigner      
theKompany.com     Data Architect     

If you know of any other applications that work with Connector/ODBC,
please send mail to <myodbc@lists.mysql.com> about them.


File: manual.info,  Node: connector-odbc-examples-tools-with-access,  Next: connector-odbc-examples-tools-with-wordexcel,  Prev: connector-odbc-examples-tools,  Up: connector-odbc-examples

20.1.5.4 Using Connector/ODBC with Microsoft Access
...................................................

* Menu:

* connector-odbc-examples-tools-with-access-export::  Exporting Access Data to MySQL
* connector-odbc-examples-tools-with-access-import::  Importing MySQL Data to Access
* connector-odbc-examples-tools-with-access-linked-tables::  Using Microsoft Access as a Front-end to MySQL

You can use MySQL database with Microsoft Access using Connector/ODBC.
The MySQL database can be used as an import source, an export source,
or as a linked table for direct use within an Access application, so
you can use Access as the front-end interface to a MySQL database.


File: manual.info,  Node: connector-odbc-examples-tools-with-access-export,  Next: connector-odbc-examples-tools-with-access-import,  Prev: connector-odbc-examples-tools-with-access,  Up: connector-odbc-examples-tools-with-access

20.1.5.5 Exporting Access Data to MySQL
.......................................

To export a table of data from an Access database to MySQL, follow
these instructions:

  1. When you open an Access database or an Access project, a Database
     window appears. It displays shortcuts for creating new database
     objects and opening existing objects.

     Access Database

  2. Click the name of the `table' or `query' you want to export, and
     then in the `File' menu, select `Export'.

  3. In the `Export Object Type OBJECT NAME To' dialog box, in the
     `Save As Type' box, select `ODBC Databases ()' as shown here:

     Selecting an ODBC Database

  4. In the `Export' dialog box, enter a name for the file (or use the
     suggested name), and then select `OK'.

  5. The Select Data Source dialog box is displayed; it lists the
     defined data sources for any ODBC drivers installed on your
     computer. Click either the File Data Source or Machine Data Source
     tab, and then double-click the Connector/ODBC or Connector/ODBC
     3.51 data source that you want to export to. To define a new data
     source for Connector/ODBC, please *Note
     connector-odbc-configuration-dsn-windows::.

*Note*:

Ensure that the information that you are exporting to the MySQL table
is valid for the corresponding MySQL data types.  Values that are
outside of the supported range of the MySQL data type but valid within
Access may trigger an `overflow' error during the export.

Microsoft Access connects to the MySQL Server through this data source
and exports new tables and or data.


File: manual.info,  Node: connector-odbc-examples-tools-with-access-import,  Next: connector-odbc-examples-tools-with-access-linked-tables,  Prev: connector-odbc-examples-tools-with-access-export,  Up: connector-odbc-examples-tools-with-access

20.1.5.6 Importing MySQL Data to Access
.......................................

To import a table or tables from MySQL to Access, follow these
instructions:

  1. Open a database, or switch to the Database window for the open
     database.

  2. To import tables, on the `File' menu, point to `Get External
     Data', and then click `Import'.

  3. In the `Import' dialog box, in the Files Of Type box, select `ODBC
     Databases ()'. The Select Data Source dialog box lists the defined
     data sources `The Select Data Source' dialog box is displayed; it
     lists the defined data source names.

  4. If the ODBC data source that you selected requires you to log on,
     enter your login ID and password (additional information might
     also be required), and then click `OK'.

  5. Microsoft Access connects to the MySQL server through `ODBC data
     source ' and displays the list of tables that you can `import'.

  6. Click each table that you want to `import', and then click `OK'.


File: manual.info,  Node: connector-odbc-examples-tools-with-access-linked-tables,  Prev: connector-odbc-examples-tools-with-access-import,  Up: connector-odbc-examples-tools-with-access

20.1.5.7 Using Microsoft Access as a Front-end to MySQL
.......................................................

You can use Microsoft Access as a front end to a MySQL database by
linking tables within your Microsoft Access database to tables that
exist within your MySQL database. When a query is requested on a table
within Access, ODBC is used to execute the queries on the MySQL
database instead.

*To create a linked table*:

  1. Open the Access database that you want to link to MySQL.

  2. From the `File', choose `Get External Data->Link Tables'.

     Linking Microsoft Access tables to MySQL tables

  3. From the browser, choose `ODBC Databases ()' from the `Files of
     type' pop-up.

  4. In the `Select Data Source' window, choose an existing DSN, either
     from a `File Data Source' or `Machine Data Source'.You can also
     create a new DSN using the `New...' button. For more information
     on creating a DSN see *Note
     connector-odbc-configuration-dsn-windows::.

     Linking Microsoft Access tables to MySQL tables, choosing a DSN

  5. In the `Link Tables' dialog, select one or more tables from the
     MySQL database. A link will be created to each table that you
     select from this list.

     Linking Microsoft Access tables to MySQL tables, table selection

  6. If Microsoft Access is unable to determine the unique record
     identifier for a table automatically then it may ask you to
     confirm the column, or combination of columns, to be used to
     uniquely identify each row from the source table. Select the
     columns you want to use and click `OK'.

     Linking Microsoft Access tables to MySQL tables, choosing unique
     record identifier

Once the process has been completed, you can now build interfaces and
queries to the linked tables just as you would for any Access database.

Use the following procedure to view or to refresh links when the
structure or location of a linked table has changed. The Linked Table
Manager lists the paths to all currently linked tables.

*To view or refresh links*:

  1. Open the database that contains links to MySQL tables.

  2. On the `Tools' menu, point to `Add-ins' (`Database Utilities' in
     Access 2000 or newer), and then click `Linked Table Manager'.

  3. Select the check box for the tables whose links you want to
     refresh.

  4. Click OK to refresh the links.

Microsoft Access confirms a successful refresh or, if the table wasn't
found, displays the `Select New Location of' <table name> dialog box in
which you can specify its the table's new location. If several selected
tables have moved to the new location that you specify, the Linked
Table Manager searches that location for all selected tables, and
updates all links in one step.

*To change the path for a set of linked tables*:

  1. Open the database that contains links to tables.

  2. On the `Tools' menu, point to `Add-ins' (`Database Utilities' in
     Access 2000 or newer), and then click `Linked Table Manager'.

  3. Select the `Always Prompt For A New Location' check box.

  4. Select the check box for the tables whose links you want to
     change, and then click `OK'.

  5. In the `Select New Location of' <table name> dialog box, specify
     the new location, click `Open', and then click `OK'.


File: manual.info,  Node: connector-odbc-examples-tools-with-wordexcel,  Next: connector-odbc-examples-tools-with-crystalreports,  Prev: connector-odbc-examples-tools-with-access,  Up: connector-odbc-examples

20.1.5.8 Using Connector/ODBC with Microsoft Word or Excel
..........................................................

You can use Microsoft Word and Microsoft Excel to access information
from a MySQL database using Connector/ODBC. Within Microsoft Word, this
facility is most useful when importing data for mailmerge, or for
tables and data to be included in reports.  Within Microsoft Excel, you
can execute queries on your MySQL server and import the data directly
into an Excel Worksheet, presenting the data as a series of rows and
columns.

With both applications, data is accessed and imported into the
application using Microsoft Query , which enables you to execute a
query though an ODBC source. You use Microsoft Query to build the SQL
statement to be executed, selecting the tables, fields, selection
criteria and sort order.  For example, to insert information from a
table in the World test database into an Excel spreadsheet, using the
DSN samples shown in *Note connector-odbc-configuration:::

  1. Create a new Worksheet.

  2. From the `Data' menu, choose `Import External Data', and then
     select `New Database Query'.

  3. Microsoft Query will start.  First, you need to choose the data
     source, by selecting an existing Data Source Name.

     Microsoft Query, Choose Data Source

  4. Within the `Query Wizard', you must choose the columns that you
     want to import. The list of tables available to the user
     configured through the DSN is shown on the left, the columns that
     will be added to your query are shown on the right. The columns
     you choose are equivalent to those in the first section of a *Note
     `SELECT': select. query. Click `Next' to continue.

     Microsoft Query, Choose Columns

  5. You can filter rows from the query (the equivalent of a `WHERE'
     clause) using the `Filter Data' dialog. Click `Next' to continue.

     Microsoft Query, Filter Data

  6. Select an (optional) sort order for the data. This is equivalent
     to using a `ORDER BY' clause in your SQL query. You can select up
     to three fields for sorting the information returned by the query.
     Click `Next' to continue.

     Microsoft Query, Sort Order

  7. Select the destination for your query. You can select to return
     the data Microsoft Excel, where you can choose a worksheet and
     cell where the data will be inserted; you can continue to view the
     query and results within Microsoft Query, where you can edit the
     SQL query and further filter and sort the information returned; or
     you can create an OLAP Cube from the query, which can then be used
     directly within Microsoft Excel. Click `Finish'.

     Microsoft Query, Selecting a destination

The same process can be used to import data into a Word document, where
the data will be inserted as a table. This can be used for mail merge
purposes (where the field data is read from a Word table), or where you
want to include data and reports within a report or other document.


File: manual.info,  Node: connector-odbc-examples-tools-with-crystalreports,  Next: connector-odbc-examples-programming,  Prev: connector-odbc-examples-tools-with-wordexcel,  Up: connector-odbc-examples

20.1.5.9 Using Connector/ODBC with Crystal Reports
..................................................

Crystal Reports can use an ODBC DSN to connect to a database from which
you to extract data and information for reporting purposes.

*Note*:

There is a known issue with certain versions of Crystal Reports where
the application is unable to open and browse tables and fields through
an ODBC connection. Before using Crystal Reports with MySQL, please
ensure that you have update to the latest version, including any
outstanding service packs and hotfixes. For more information on this
issue, see the Business) Objects Knowledgebase
(http://support.crystaldecisions.com/library/kbase/new_articles/c2013269.asp)
for more information.

For example, to create a simple crosstab report within Crystal Reports
XI, you should follow these steps:

  1. Create a DSN using the `Data Sources (ODBC)' tool. You can either
     specify a complete database, including user name and password, or
     you can build a basic DSN and use Crystal Reports to set the user
     name and password.

     For the purposes of this example, a DSN that provides a connection
     to an instance of the MySQL Sakila sample database has been
     created.

  2. Open Crystal Reports and create a new project, or an open an
     existing reporting project into which you want to insert data from
     your MySQL data source.

  3. Start the Cross-Tab Report Wizard, either by clicking on the
     option on the Start Page. Expand the `Create New Connection'
     folder, then expand the `ODBC (RDO)' folder to obtain a list of
     ODBC data sources.

     You will be asked to select a data source.

     Selecting an Data Source in Crystal Reports

  4. When you first expand the `ODBC (RDO)' folder you will be
     presented the Data Source Selection screen. From here you can
     select either a pre-configured DSN, open a file-based DSN or enter
     and manual connection string. For this example, the `Sakila' DSN
     will be used.

     If the DSN contains a user name/password combination, or you want
     to use different authentication credentials, click `Next' to enter
     the user name and password that you want to use. Otherwise, click
     `Finish' to continue the data source selection wizard.

     Selecting an ODBC Data Source in Crystal Reports

  5. You will be returned the Cross-Tab Report Creation Wizard.  You
     now need to select the database and tables that you want to
     include in your report. For our example, we will expand the
     selected Sakila database. Click the `city' table and use the `>'
     button to add the table to the report. Then repeat the action with
     the `country' table. Alternatively you can select multiple tables
     and add them to the report.

     Finally, you can select the parent `Sakila' resource and add of
     the tables to the report.

     Once you have selected the tables you want to include, click
     `Next' to continue.

     Selecting an tables in Crystal Reports

  6. Crystal Reports will now read the table definitions and
     automatically identify the links between the tables. The
     identification of links between tables enables Crystal Reports to
     automatically lookup and summarize information based on all the
     tables in the database according to your query. If Crystal Reports
     is unable to perform the linking itself, you can manually create
     the links between fields in the tables you have selected.

     Click `Next' to continue the process.

     Table links/structure in Crystal Reports

  7. You can now select the columns and rows that you wish to include
     within the Cross-Tab report. Drag and drop or use the `>' buttons
     to add fields to each area of the report. In the example shown, we
     will report on cities, organized by country, incorporating a count
     of the number of cities within each country. If you want to browse
     the data, select a field and click the `Browse Data...' button.

     Click `Next' to create a graph of the results. Since we are not
     creating a graph from this data, click `Finish' to generate the
     report.

     Cross-tab definition in Crystal Reports

  8. The finished report will be shown, a sample of the output from the
     Sakila sample database is shown below.

     Cross-tab final report in Crystal Reports

Once the ODBC connection has been opened within Crystal Reports, you
can browse and add any fields within the available tables into your
reports.


File: manual.info,  Node: connector-odbc-examples-programming,  Prev: connector-odbc-examples-tools-with-crystalreports,  Up: connector-odbc-examples

20.1.5.10 Connector/ODBC Programming
....................................

* Menu:

* connector-odbc-examples-programming-vb::  Using Connector/ODBC with Visual Basic Using ADO, DAO and RDO
* connector-odbc-examples-programming-net::  Using Connector/ODBC with .NET

With a suitable ODBC Manager and the Connector/ODBC driver installed,
any programming language or environment that can support ODBC should be
able to connect to a MySQL database through Connector/ODBC.

This includes, but is certainly not limited to, Microsoft support
languages (including Visual Basic, C# and interfaces such as ODBC.NET),
Perl (through the DBI module, and the DBD::ODBC driver).


File: manual.info,  Node: connector-odbc-examples-programming-vb,  Next: connector-odbc-examples-programming-net,  Prev: connector-odbc-examples-programming,  Up: connector-odbc-examples-programming

20.1.5.11 Using Connector/ODBC with Visual Basic Using ADO, DAO and RDO
.......................................................................

* Menu:

* connector-odbc-examples-programming-vb-ado::  ADO: `rs.addNew', `rs.delete', and `rs.update'
* connector-odbc-examples-programming-vb-dao::  DAO: `rs.addNew', `rs.update', and Scrolling
* connector-odbc-examples-programming-vb-rdo::  RDO: `rs.addNew' and `rs.update'

This section contains simple examples of the use of MySQL ODBC 3.51
Driver with ADO, DAO and RDO.


File: manual.info,  Node: connector-odbc-examples-programming-vb-ado,  Next: connector-odbc-examples-programming-vb-dao,  Prev: connector-odbc-examples-programming-vb,  Up: connector-odbc-examples-programming-vb

20.1.5.12 ADO: `rs.addNew', `rs.delete', and `rs.update'
........................................................

The following ADO (ActiveX Data Objects) example creates a table
`my_ado' and demonstrates the use of `rs.addNew', `rs.delete', and
`rs.update'.

     Private Sub myodbc_ado_Click()

     Dim conn As ADODB.Connection
     Dim rs As ADODB.Recordset
     Dim fld As ADODB.Field
     Dim sql As String

     'connect to MySQL server using MySQL ODBC 3.51 Driver
     Set conn = New ADODB.Connection
     conn.ConnectionString = "DRIVER={MySQL ODBC 3.51 Driver};"_
     & "SERVER=localhost;"_
     & " DATABASE=test;"_
     & "UID=venu;PWD=venu; OPTION=3"

     conn.Open

     'create table
     conn.Execute "DROP TABLE IF EXISTS my_ado"
     conn.Execute "CREATE TABLE my_ado(id int not null primary key, name varchar(20)," _
     & "txt text, dt date, tm time, ts timestamp)"

     'direct insert
     conn.Execute "INSERT INTO my_ado(id,name,txt) values(1,100,'venu')"
     conn.Execute "INSERT INTO my_ado(id,name,txt) values(2,200,'MySQL')"
     conn.Execute "INSERT INTO my_ado(id,name,txt) values(3,300,'Delete')"

     Set rs = New ADODB.Recordset
     rs.CursorLocation = adUseServer

     'fetch the initial table ..
     rs.Open "SELECT * FROM my_ado", conn
     Debug.Print rs.RecordCount
     rs.MoveFirst
     Debug.Print String(50, "-") & "Initial my_ado Result Set " & String(50, "-")
     For Each fld In rs.Fields
     Debug.Print fld.Name,
     Next
     Debug.Print

     Do Until rs.EOF
     For Each fld In rs.Fields
     Debug.Print fld.Value,
     Next
     rs.MoveNext
     Debug.Print
     Loop
     rs.Close

     'rs insert
     rs.Open "select * from my_ado", conn, adOpenDynamic, adLockOptimistic
     rs.AddNew
     rs!Name = "Monty"
     rs!txt = "Insert row"
     rs.Update
     rs.Close

     'rs update
     rs.Open "SELECT * FROM my_ado"
     rs!Name = "update"
     rs!txt = "updated-row"
     rs.Update
     rs.Close

     'rs update second time..
     rs.Open "SELECT * FROM my_ado"
     rs!Name = "update"
     rs!txt = "updated-second-time"
     rs.Update
     rs.Close

     'rs delete
     rs.Open "SELECT * FROM my_ado"
     rs.MoveNext
     rs.MoveNext
     rs.Delete
     rs.Close

     'fetch the updated table ..
     rs.Open "SELECT * FROM my_ado", conn
     Debug.Print rs.RecordCount
     rs.MoveFirst
     Debug.Print String(50, "-") & "Updated my_ado Result Set " & String(50, "-")
     For Each fld In rs.Fields
     Debug.Print fld.Name,
     Next
     Debug.Print

     Do Until rs.EOF
     For Each fld In rs.Fields
     Debug.Print fld.Value,
     Next
     rs.MoveNext
     Debug.Print
     Loop
     rs.Close
     conn.Close
     End Sub


File: manual.info,  Node: connector-odbc-examples-programming-vb-dao,  Next: connector-odbc-examples-programming-vb-rdo,  Prev: connector-odbc-examples-programming-vb-ado,  Up: connector-odbc-examples-programming-vb

20.1.5.13 DAO: `rs.addNew', `rs.update', and Scrolling
......................................................

The following DAO (Data Access Objects) example creates a table
`my_dao' and demonstrates the use of `rs.addNew', `rs.update', and
result set scrolling.

     Private Sub myodbc_dao_Click()

     Dim ws As Workspace
     Dim conn As Connection
     Dim queryDef As queryDef
     Dim str As String

     'connect to MySQL using MySQL ODBC 3.51 Driver
     Set ws = DBEngine.CreateWorkspace("", "venu", "venu", dbUseODBC)
     str = "odbc;DRIVER={MySQL ODBC 3.51 Driver};"_
     & "SERVER=localhost;"_
     & " DATABASE=test;"_
     & "UID=venu;PWD=venu; OPTION=3"
     Set conn = ws.OpenConnection("test", dbDriverNoPrompt, False, str)

     'Create table my_dao
     Set queryDef = conn.CreateQueryDef("", "drop table if exists my_dao")
     queryDef.Execute

     Set queryDef = conn.CreateQueryDef("", "create table my_dao(Id INT AUTO_INCREMENT PRIMARY KEY, " _
     & "Ts TIMESTAMP(14) NOT NULL, Name varchar(20), Id2 INT)")
     queryDef.Execute

     'Insert new records using rs.addNew
     Set rs = conn.OpenRecordset("my_dao")
     Dim i As Integer

     For i = 10 To 15
     rs.AddNew
     rs!Name = "insert record" & i
     rs!Id2 = i
     rs.Update
     Next i
     rs.Close

     'rs update..
     Set rs = conn.OpenRecordset("my_dao")
     rs.Edit
     rs!Name = "updated-string"
     rs.Update
     rs.Close

     'fetch the table back...
     Set rs = conn.OpenRecordset("my_dao", dbOpenDynamic)
     str = "Results:"
     rs.MoveFirst
     While Not rs.EOF
     str = " " & rs!Id & " , " & rs!Name & ", " & rs!Ts & ", " & rs!Id2
     Debug.Print "DATA:" & str
     rs.MoveNext
     Wend

     'rs Scrolling
     rs.MoveFirst
     str = " FIRST ROW: " & rs!Id & " , " & rs!Name & ", " & rs!Ts & ", " & rs!Id2
     Debug.Print str

     rs.MoveLast
     str = " LAST ROW: " & rs!Id & " , " & rs!Name & ", " & rs!Ts & ", " & rs!Id2
     Debug.Print str

     rs.MovePrevious
     str = " LAST-1 ROW: " & rs!Id & " , " & rs!Name & ", " & rs!Ts & ", " & rs!Id2
     Debug.Print str

     'free all resources
     rs.Close
     queryDef.Close
     conn.Close
     ws.Close

     End Sub


File: manual.info,  Node: connector-odbc-examples-programming-vb-rdo,  Prev: connector-odbc-examples-programming-vb-dao,  Up: connector-odbc-examples-programming-vb

20.1.5.14 RDO: `rs.addNew' and `rs.update'
..........................................

The following RDO (Remote Data Objects) example creates a table
`my_rdo' and demonstrates the use of `rs.addNew' and `rs.update'.

     Dim rs As rdoResultset
     Dim cn As New rdoConnection
     Dim cl As rdoColumn
     Dim SQL As String

     'cn.Connect = "DSN=test;"
     cn.Connect = "DRIVER={MySQL ODBC 3.51 Driver};"_
     & "SERVER=localhost;"_
     & " DATABASE=test;"_
     & "UID=venu;PWD=venu; OPTION=3"

     cn.CursorDriver = rdUseOdbc
     cn.EstablishConnection rdDriverPrompt

     'drop table my_rdo
     SQL = "drop table if exists my_rdo"
     cn.Execute SQL, rdExecDirect

     'create table my_rdo
     SQL = "create table my_rdo(id int, name varchar(20))"
     cn.Execute SQL, rdExecDirect

     'insert - direct
     SQL = "insert into my_rdo values (100,'venu')"
     cn.Execute SQL, rdExecDirect

     SQL = "insert into my_rdo values (200,'MySQL')"
     cn.Execute SQL, rdExecDirect

     'rs insert
     SQL = "select * from my_rdo"
     Set rs = cn.OpenResultset(SQL, rdOpenStatic, rdConcurRowVer, rdExecDirect)
     rs.AddNew
     rs!id = 300
     rs!Name = "Insert1"
     rs.Update
     rs.Close

     'rs insert
     SQL = "select * from my_rdo"
     Set rs = cn.OpenResultset(SQL, rdOpenStatic, rdConcurRowVer, rdExecDirect)
     rs.AddNew
     rs!id = 400
     rs!Name = "Insert 2"
     rs.Update
     rs.Close

     'rs update
     SQL = "select * from my_rdo"
     Set rs = cn.OpenResultset(SQL, rdOpenStatic, rdConcurRowVer, rdExecDirect)
     rs.Edit
     rs!id = 999
     rs!Name = "updated"
     rs.Update
     rs.Close

     'fetch back...
     SQL = "select * from my_rdo"
     Set rs = cn.OpenResultset(SQL, rdOpenStatic, rdConcurRowVer, rdExecDirect)
     Do Until rs.EOF
     For Each cl In rs.rdoColumns
     Debug.Print cl.Value,
     Next
     rs.MoveNext
     Debug.Print
     Loop
     Debug.Print "Row count="; rs.RowCount

     'close
     rs.Close
     cn.Close

     End Sub


File: manual.info,  Node: connector-odbc-examples-programming-net,  Prev: connector-odbc-examples-programming-vb,  Up: connector-odbc-examples-programming

20.1.5.15 Using Connector/ODBC with .NET
........................................

* Menu:

* connector-odbc-examples-programming-net-csharp::  Using Connector/ODBC with ODBC.NET and C# (C sharp)
* connector-odbc-examples-programming-net-vb::  Using Connector/ODBC with ODBC.NET and Visual Basic

This section contains simple examples that demonstrate the use of
Connector/ODBC drivers with ODBC.NET.


File: manual.info,  Node: connector-odbc-examples-programming-net-csharp,  Next: connector-odbc-examples-programming-net-vb,  Prev: connector-odbc-examples-programming-net,  Up: connector-odbc-examples-programming-net

20.1.5.16 Using Connector/ODBC with ODBC.NET and C# (C sharp)
.............................................................

The following sample creates a table `my_odbc_net' and demonstrates its
use in C#.

     /**
      * @sample    : mycon.cs
      * @purpose   : Demo sample for ODBC.NET using Connector/ODBC
      * @author    : Venu, <myodbc@lists.mysql.com>
      *
      * (C) Copyright MySQL AB, 1995-2006
      *
      **/

     /* build command
      *
      *  csc /t:exe
      *      /out:mycon.exe mycon.cs
      *      /r:Microsoft.Data.Odbc.dll
      */

     using Console = System.Console;
     using Microsoft.Data.Odbc;

     namespace myodbc3
     {
       class mycon
       {
         static void Main(string[] args)
         {
           try
             {
               //Connection string for Connector/ODBC 3.51
               string MyConString = "DRIVER={MySQL ODBC 3.51 Driver};" +
                 "SERVER=localhost;" +
                 "DATABASE=test;" +
                 "UID=venu;" +
                 "PASSWORD=venu;" +
                 "OPTION=3";

               //Connect to MySQL using Connector/ODBC
               OdbcConnection MyConnection = new OdbcConnection(MyConString);
               MyConnection.Open();

               Console.WriteLine("\n !!! success, connected successfully !!!\n");

               //Display connection information
               Console.WriteLine("Connection Information:");
               Console.WriteLine("\tConnection String:" +
                                 MyConnection.ConnectionString);
               Console.WriteLine("\tConnection Timeout:" +
                                 MyConnection.ConnectionTimeout);
               Console.WriteLine("\tDatabase:" +
                                 MyConnection.Database);
               Console.WriteLine("\tDataSource:" +
                                 MyConnection.DataSource);
               Console.WriteLine("\tDriver:" +
                                 MyConnection.Driver);
               Console.WriteLine("\tServerVersion:" +
                                 MyConnection.ServerVersion);

               //Create a sample table
               OdbcCommand MyCommand =
                 new OdbcCommand("DROP TABLE IF EXISTS my_odbc_net",
                                 MyConnection);
               MyCommand.ExecuteNonQuery();
               MyCommand.CommandText =
                 "CREATE TABLE my_odbc_net(id int, name varchar(20), idb bigint)";
               MyCommand.ExecuteNonQuery();

               //Insert
               MyCommand.CommandText =
                 "INSERT INTO my_odbc_net VALUES(10,'venu', 300)";
               Console.WriteLine("INSERT, Total rows affected:" +
                                 MyCommand.ExecuteNonQuery());;

               //Insert
               MyCommand.CommandText =
                 "INSERT INTO my_odbc_net VALUES(20,'mysql',400)";
               Console.WriteLine("INSERT, Total rows affected:" +
                                 MyCommand.ExecuteNonQuery());

               //Insert
               MyCommand.CommandText =
                 "INSERT INTO my_odbc_net VALUES(20,'mysql',500)";
               Console.WriteLine("INSERT, Total rows affected:" +
                                 MyCommand.ExecuteNonQuery());

               //Update
               MyCommand.CommandText =
                 "UPDATE my_odbc_net SET id=999 WHERE id=20";
               Console.WriteLine("Update, Total rows affected:" +
                                 MyCommand.ExecuteNonQuery());

               //COUNT(*)
               MyCommand.CommandText =
                 "SELECT COUNT(*) as TRows FROM my_odbc_net";
               Console.WriteLine("Total Rows:" +
                                 MyCommand.ExecuteScalar());

               //Fetch
               MyCommand.CommandText = "SELECT * FROM my_odbc_net";
               OdbcDataReader MyDataReader;
               MyDataReader =  MyCommand.ExecuteReader();
               while (MyDataReader.Read())
                 {
                   if(string.Compare(MyConnection.Driver,"myodbc3.dll") == 0) {
                     //Supported only by Connector/ODBC 3.51
                     Console.WriteLine("Data:" + MyDataReader.GetInt32(0) + " " +
                                       MyDataReader.GetString(1) + " " +
                                       MyDataReader.GetInt64(2));
                   }
                   else {
                     //BIGINTs not supported by Connector/ODBC
                     Console.WriteLine("Data:" + MyDataReader.GetInt32(0) + " " +
                                       MyDataReader.GetString(1) + " " +
                                       MyDataReader.GetInt32(2));
                   }
                 }

               //Close all resources
               MyDataReader.Close();
               MyConnection.Close();
             }
           catch (OdbcException MyOdbcException) //Catch any ODBC exception ..
             {
               for (int i=0; i < MyOdbcException.Errors.Count; i++)
                 {
                   Console.Write("ERROR #" + i + "\n" +
                                 "Message: " +
                                 MyOdbcException.Errors[i].Message + "\n" +
                                 "Native: " +
                                 MyOdbcException.Errors[i].NativeError.ToString() + "\n" +
                                 "Source: " +
                                 MyOdbcException.Errors[i].Source + "\n" +
                                 "SQL: " +
                                 MyOdbcException.Errors[i].SQLState + "\n");
                 }
             }
         }
       }
     }


File: manual.info,  Node: connector-odbc-examples-programming-net-vb,  Prev: connector-odbc-examples-programming-net-csharp,  Up: connector-odbc-examples-programming-net

20.1.5.17 Using Connector/ODBC with ODBC.NET and Visual Basic
.............................................................

The following sample creates a table `my_vb_net' and demonstrates the
use in VB.

     ' @sample    : myvb.vb
     ' @purpose   : Demo sample for ODBC.NET using Connector/ODBC
     ' @author    : Venu, <myodbc@lists.mysql.com>
     '
     ' (C) Copyright MySQL AB, 1995-2006
     '
     '

     '
     ' build command
     '
     ' vbc /target:exe
     '     /out:myvb.exe
     '     /r:Microsoft.Data.Odbc.dll
     '     /r:System.dll
     '     /r:System.Data.dll
     '

     Imports Microsoft.Data.Odbc
     Imports System

     Module myvb
       Sub Main()
         Try

           'Connector/ODBC 3.51 connection string
           Dim MyConString As String = "DRIVER={MySQL ODBC 3.51 Driver};" & _
           "SERVER=localhost;" & _
           "DATABASE=test;" & _
           "UID=venu;" & _
           "PASSWORD=venu;" & _
           "OPTION=3;"

           'Connection
           Dim MyConnection As New OdbcConnection(MyConString)
           MyConnection.Open()

           Console.WriteLine("Connection State::" & MyConnection.State.ToString)

           'Drop
           Console.WriteLine("Dropping table")
           Dim MyCommand As New OdbcCommand()
           MyCommand.Connection = MyConnection
           MyCommand.CommandText = "DROP TABLE IF EXISTS my_vb_net"
           MyCommand.ExecuteNonQuery()

           'Create
           Console.WriteLine("Creating....")
           MyCommand.CommandText = "CREATE TABLE my_vb_net(id int, name varchar(30))"
           MyCommand.ExecuteNonQuery()

           'Insert
           MyCommand.CommandText = "INSERT INTO my_vb_net VALUES(10,'venu')"
           Console.WriteLine("INSERT, Total rows affected:" & _
           MyCommand.ExecuteNonQuery())

           'Insert
           MyCommand.CommandText = "INSERT INTO my_vb_net VALUES(20,'mysql')"
           Console.WriteLine("INSERT, Total rows affected:" & _
           MyCommand.ExecuteNonQuery())

           'Insert
           MyCommand.CommandText = "INSERT INTO my_vb_net VALUES(20,'mysql')"
           Console.WriteLine("INSERT, Total rows affected:" & _
           MyCommand.ExecuteNonQuery())

           'Insert
           MyCommand.CommandText = "INSERT INTO my_vb_net(id) VALUES(30)"
           Console.WriteLine("INSERT, Total rows affected:" & _
                             MyCommand.ExecuteNonQuery())

           'Update
           MyCommand.CommandText = "UPDATE my_vb_net SET id=999 WHERE id=20"
           Console.WriteLine("Update, Total rows affected:" & _
           MyCommand.ExecuteNonQuery())

           'COUNT(*)
           MyCommand.CommandText = "SELECT COUNT(*) as TRows FROM my_vb_net"
           Console.WriteLine("Total Rows:" & MyCommand.ExecuteScalar())

           'Select
           Console.WriteLine("Select * FROM my_vb_net")
           MyCommand.CommandText = "SELECT * FROM my_vb_net"
           Dim MyDataReader As OdbcDataReader
           MyDataReader = MyCommand.ExecuteReader
           While MyDataReader.Read
             If MyDataReader("name") Is DBNull.Value Then
               Console.WriteLine("id = " & _
               CStr(MyDataReader("id")) & "  name = " & _
               "NULL")
             Else
               Console.WriteLine("id = " & _
               CStr(MyDataReader("id")) & "  name = " & _
               CStr(MyDataReader("name")))
             End If
           End While

           'Catch ODBC Exception
         Catch MyOdbcException As OdbcException
           Dim i As Integer
           Console.WriteLine(MyOdbcException.ToString)

           'Catch program exception
         Catch MyException As Exception
           Console.WriteLine(MyException.ToString)
         End Try
       End Sub


File: manual.info,  Node: connector-odbc-reference,  Next: connector-odbc-usagenotes,  Prev: connector-odbc-examples,  Up: connector-odbc

20.1.6 Connector/ODBC Reference
-------------------------------

* Menu:

* connector-odbc-reference-api::  Connector/ODBC API Reference
* connector-odbc-reference-datatypes::  Connector/ODBC Data Types
* connector-odbc-reference-errorcodes::  Connector/ODBC Error Codes

This section provides reference material for the Connector/ODBC API,
showing supported functions and methods, supported MySQL column types
and the corresponding native type in Connector/ODBC, and the error
codes returned by Connector/ODBC when a fault occurs.


File: manual.info,  Node: connector-odbc-reference-api,  Next: connector-odbc-reference-datatypes,  Prev: connector-odbc-reference,  Up: connector-odbc-reference

20.1.6.1 Connector/ODBC API Reference
.....................................

This section summarizes ODBC routines, categorized by functionality.

For the complete ODBC API reference, please refer to the ODBC
Programmer's Reference at
`http://msdn.microsoft.com/en-us/library/ms714177.aspx'.

An application can call `SQLGetInfo' function to obtain conformance
information about Connector/ODBC. To obtain information about support
for a specific function in the driver, an application can call
`SQLGetFunctions'.

*Note*:

For backward compatibility, the Connector/ODBC 3.51 driver supports all
deprecated functions.

The following tables list Connector/ODBC API calls grouped by task:

*Connecting to a data source*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLAllocHandle'    Yes       ISO 92    Obtains an environment, connection,
                                        statement, or descriptor handle.
`SQLConnect'        Yes       ISO 92    Connects to a specific driver by
                                        data source name, user ID, and
                                        password.
`SQLDriverConnect'  Yes       ODBC      Connects to a specific driver by
                                        connection string or requests that
                                        the Driver Manager and driver
                                        display connection dialog boxes for
                                        the user.
`SQLAllocEnv'       Yes       DeprecatedObtains an environment handle
                                        allocated from driver.
`SQLAllocConnect'   Yes       DeprecatedObtains a connection handle

*Obtaining information about a driver and data source*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLDataSources'    No        ISO 92    Returns the list of available data
                                        sources, handled by the Driver
                                        Manager
`SQLDrivers'        No        ODBC      Returns the list of installed
                                        drivers and their attributes,
                                        handles by Driver Manager
`SQLGetInfo'        Yes       ISO 92    Returns information about a
                                        specific driver and data source.
`SQLGetFunctions'   Yes       ISO 92    Returns supported driver functions.
`SQLGetTypeInfo'    Yes       ISO 92    Returns information about supported
                                        data types.

*Setting and retrieving driver attributes*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLSetConnectAttr' Yes       ISO 92    Sets a connection attribute.
`SQLGetConnectAttr' Yes       ISO 92    Returns the value of a connection
                                        attribute.
`SQLSetConnectOption'Yes       DeprecatedSets a connection option
`SQLGetConnectOption'Yes       DeprecatedReturns the value of a connection
                                        option
`SQLSetEnvAttr'     Yes       ISO 92    Sets an environment attribute.
`SQLGetEnvAttr'     Yes       ISO 92    Returns the value of an environment
                                        attribute.
`SQLSetStmtAttr'    Yes       ISO 92    Sets a statement attribute.
`SQLGetStmtAttr'    Yes       ISO 92    Returns the value of a statement
                                        attribute.
`SQLSetStmtOption'  Yes       DeprecatedSets a statement option
`SQLGetStmtOption'  Yes       DeprecatedReturns the value of a statement
                                        option

*Preparing SQL requests*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLAllocStmt'      Yes       DeprecatedAllocates a statement handle
`SQLPrepare'        Yes       ISO 92    Prepares an SQL statement for later
                                        execution.
`SQLBindParameter'  Yes       ODBC      Assigns storage for a parameter in
                                        an SQL statement.
`SQLGetCursorName'  Yes       ISO 92    Returns the cursor name associated
                                        with a statement handle.
`SQLSetCursorName'  Yes       ISO 92    Specifies a cursor name.
`SQLSetScrollOptions'Yes       ODBC      Sets options that control cursor
                                        behavior.

*Submitting requests*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLExecute'        Yes       ISO 92    Executes a prepared statement.
`SQLExecDirect'     Yes       ISO 92    Executes a statement
`SQLNativeSql'      Yes       ODBC      Returns the text of an SQL
                                        statement as translated by the
                                        driver.
`SQLDescribeParam'  Yes       ODBC      Returns the description for a
                                        specific parameter in a statement.
`SQLNumParams'      Yes       ISO 92    Returns the number of parameters in
                                        a statement.
`SQLParamData'      Yes       ISO 92    Used in conjunction with
                                        `SQLPutData' to supply parameter
                                        data at execution time. (Useful for
                                        long data values.)
`SQLPutData'        Yes       ISO 92    Sends part or all of a data value
                                        for a parameter. (Useful for long
                                        data values.)

*Retrieving results and information about results*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLRowCount'       Yes       ISO 92    Returns the number of rows affected
                                        by an insert, update, or delete
                                        request.
`SQLNumResultCols'  Yes       ISO 92    Returns the number of columns in
                                        the result set.
`SQLDescribeCol'    Yes       ISO 92    Describes a column in the result
                                        set.
`SQLColAttribute'   Yes       ISO 92    Describes attributes of a column in
                                        the result set.
`SQLColAttributes'  Yes       DeprecatedDescribes attributes of a column in
                                        the result set.
`SQLFetch'          Yes       ISO 92    Returns multiple result rows.
`SQLFetchScroll'    Yes       ISO 92    Returns scrollable result rows.
`SQLExtendedFetch'  Yes       DeprecatedReturns scrollable result rows.
`SQLSetPos'         Yes       ODBC      Positions a cursor within a fetched
                                        block of data and allows an
                                        application to refresh data in the
                                        rowset or to update or delete data
                                        in the result set.
`SQLBulkOperations' Yes       ODBC      Performs bulk insertions and bulk
                                        bookmark operations, including
                                        update, delete, and fetch by
                                        bookmark.

*Retrieving error or diagnostic information*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLError'          Yes       DeprecatedReturns additional error or status
                                        information
`SQLGetDiagField'   Yes       ISO 92    Returns additional diagnostic
                                        information (a single field of the
                                        diagnostic data structure).
`SQLGetDiagRec'     Yes       ISO 92    Returns additional diagnostic
                                        information (multiple fields of the
                                        diagnostic data structure).

*Obtaining information about the data source's system tables (catalog
functions) item*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLColumnPrivileges'Yes       ODBC      Returns a list of columns and
                                        associated privileges for one or
                                        more tables.
`SQLColumns'        Yes       X/Open    Returns the list of column names in
                                        specified tables.
`SQLForeignKeys'    Yes       ODBC      Returns a list of column names that
                                        make up foreign keys, if they exist
                                        for a specified table.
`SQLPrimaryKeys'    Yes       ODBC      Returns the list of column names
                                        that make up the primary key for a
                                        table.
`SQLSpecialColumns' Yes       X/Open    Returns information about the
                                        optimal set of columns that uniquely
                                        identifies a row in a specified
                                        table, or the columns that are
                                        automatically updated when any
                                        value in the row is updated by a
                                        transaction.
`SQLStatistics'     Yes       ISO 92    Returns statistics about a single
                                        table and the list of indexes
                                        associated with the table.
`SQLTablePrivileges'Yes       ODBC      Returns a list of tables and the
                                        privileges associated with each
                                        table.
`SQLTables'         Yes       X/Open    Returns the list of table names
                                        stored in a specific data source.

*Performing transactions*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLTransact'       Yes       DeprecatedCommits or rolls back a transaction
`SQLEndTran'        Yes       ISO 92    Commits or rolls back a transaction.

*Terminating a statement*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLFreeStmt'       Yes       ISO 92    Ends statement processing, discards
                                        pending results, and, optionally,
                                        frees all resources associated with
                                        the statement handle.
`SQLCloseCursor'    Yes       ISO 92    Closes a cursor that has been
                                        opened on a statement handle.
`SQLCancel'         Yes       ISO 92    Cancels an SQL statement.

*Terminating a connection*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLDisconnect'     Yes       ISO 92    Closes the connection.
`SQLFreeHandle'     Yes       ISO 92    Releases an environment,
                                        connection, statement, or
                                        descriptor handle.
`SQLFreeConnect'    Yes       DeprecatedReleases connection handle
`SQLFreeEnv'        Yes       DeprecatedReleases an environment handle


File: manual.info,  Node: connector-odbc-reference-datatypes,  Next: connector-odbc-reference-errorcodes,  Prev: connector-odbc-reference-api,  Up: connector-odbc-reference

20.1.6.2 Connector/ODBC Data Types
..................................

The following table illustrates how driver maps the server data types
to default SQL and C data types.

*Native Value*           *SQL Type*               *C Type*
`bigint unsigned'        `SQL_BIGINT'             `SQL_C_UBIGINT'
`bigint'                 `SQL_BIGINT'             `SQL_C_SBIGINT'
`bit'                    `SQL_BIT'                `SQL_C_BIT'
`bit'                    `SQL_CHAR'               `SQL_C_CHAR'
`blob'                   `SQL_LONGVARBINARY'      `SQL_C_BINARY'
`bool'                   `SQL_CHAR'               `SQL_C_CHAR'
`char'                   `SQL_CHAR'               `SQL_C_CHAR'
`date'                   `SQL_DATE'               `SQL_C_DATE'
`datetime'               `SQL_TIMESTAMP'          `SQL_C_TIMESTAMP'
`decimal'                `SQL_DECIMAL'            `SQL_C_CHAR'
`double precision'       `SQL_DOUBLE'             `SQL_C_DOUBLE'
`double'                 `SQL_FLOAT'              `SQL_C_DOUBLE'
`enum'                   `SQL_VARCHAR'            `SQL_C_CHAR'
`float'                  `SQL_REAL'               `SQL_C_FLOAT'
`int unsigned'           `SQL_INTEGER'            `SQL_C_ULONG'
`int'                    `SQL_INTEGER'            `SQL_C_SLONG'
`integer unsigned'       `SQL_INTEGER'            `SQL_C_ULONG'
`integer'                `SQL_INTEGER'            `SQL_C_SLONG'
`long varbinary'         `SQL_LONGVARBINARY'      `SQL_C_BINARY'
`long varchar'           `SQL_LONGVARCHAR'        `SQL_C_CHAR'
`longblob'               `SQL_LONGVARBINARY'      `SQL_C_BINARY'
`longtext'               `SQL_LONGVARCHAR'        `SQL_C_CHAR'
`mediumblob'             `SQL_LONGVARBINARY'      `SQL_C_BINARY'
`mediumint unsigned'     `SQL_INTEGER'            `SQL_C_ULONG'
`mediumint'              `SQL_INTEGER'            `SQL_C_SLONG'
`mediumtext'             `SQL_LONGVARCHAR'        `SQL_C_CHAR'
`numeric'                `SQL_NUMERIC'            `SQL_C_CHAR'
`real'                   `SQL_FLOAT'              `SQL_C_DOUBLE'
`set'                    `SQL_VARCHAR'            `SQL_C_CHAR'
`smallint unsigned'      `SQL_SMALLINT'           `SQL_C_USHORT'
`smallint'               `SQL_SMALLINT'           `SQL_C_SSHORT'
`text'                   `SQL_LONGVARCHAR'        `SQL_C_CHAR'
`time'                   `SQL_TIME'               `SQL_C_TIME'
`timestamp'              `SQL_TIMESTAMP'          `SQL_C_TIMESTAMP'
`tinyblob'               `SQL_LONGVARBINARY'      `SQL_C_BINARY'
`tinyint unsigned'       `SQL_TINYINT'            `SQL_C_UTINYINT'
`tinyint'                `SQL_TINYINT'            `SQL_C_STINYINT'
`tinytext'               `SQL_LONGVARCHAR'        `SQL_C_CHAR'
`varchar'                `SQL_VARCHAR'            `SQL_C_CHAR'
`year'                   `SQL_SMALLINT'           `SQL_C_SHORT'


File: manual.info,  Node: connector-odbc-reference-errorcodes,  Prev: connector-odbc-reference-datatypes,  Up: connector-odbc-reference

20.1.6.3 Connector/ODBC Error Codes
...................................

The following tables lists the error codes returned by the driver apart
from the server errors.

*Native *SQLSTATE 2* *SQLSTATE 3* *Error Message*
Code*                             
500     01000        01000        General warning
501     01004        01004        String data, right truncated
502     01S02        01S02        Option value changed
503     01S03        01S03        No rows updated/deleted
504     01S04        01S04        More than one row updated/deleted
505     01S06        01S06        Attempt to fetch before the result set
                                  returned the first row set
506     07001        07002        `SQLBindParameter' not used for all
                                  parameters
507     07005        07005        Prepared statement not a
                                  cursor-specification
508     07009        07009        Invalid descriptor index
509     08002        08002        Connection name in use
510     08003        08003        Connection does not exist
511     24000        24000        Invalid cursor state
512     25000        25000        Invalid transaction state
513     25S01        25S01        Transaction state unknown
514     34000        34000        Invalid cursor name
515     S1000        HY000        General driver defined error
516     S1001        HY001        Memory allocation error
517     S1002        HY002        Invalid column number
518     S1003        HY003        Invalid application buffer type
519     S1004        HY004        Invalid SQL data type
520     S1009        HY009        Invalid use of null pointer
521     S1010        HY010        Function sequence error
522     S1011        HY011        Attribute can not be set now
523     S1012        HY012        Invalid transaction operation code
524     S1013        HY013        Memory management error
525     S1015        HY015        No cursor name available
526     S1024        HY024        Invalid attribute value
527     S1090        HY090        Invalid string or buffer length
528     S1091        HY091        Invalid descriptor field identifier
529     S1092        HY092        Invalid attribute/option identifier
530     S1093        HY093        Invalid parameter number
531     S1095        HY095        Function type out of range
532     S1106        HY106        Fetch type out of range
533     S1117        HY117        Row value out of range
534     S1109        HY109        Invalid cursor position
535     S1C00        HYC00        Optional feature not implemented
0       21S01        21S01        Column count does not match value count
0       23000        23000        Integrity constraint violation
0       42000        42000        Syntax error or access violation
0       42S02        42S02        Base table or view not found
0       42S12        42S12        Index not found
0       42S21        42S21        Column already exists
0       42S22        42S22        Column not found
0       08S01        08S01        Communication link failure


File: manual.info,  Node: connector-odbc-usagenotes,  Next: connector-odbc-support,  Prev: connector-odbc-reference,  Up: connector-odbc

20.1.7 Connector/ODBC Notes and Tips
------------------------------------

* Menu:

* connector-odbc-usagenotes-functionality::  Connector/ODBC General Functionality
* connector-odbc-usagenotes-apptips::  Connector/ODBC Application Specific Tips
* connector-odbc-errors::        Connector/ODBC Errors and Resolutions (FAQ)

Here are some common notes and tips for using Connector/ODBC within
different environments, applications and tools. The notes provided here
are based on the experiences of Connector/ODBC developers and users.


File: manual.info,  Node: connector-odbc-usagenotes-functionality,  Next: connector-odbc-usagenotes-apptips,  Prev: connector-odbc-usagenotes,  Up: connector-odbc-usagenotes

20.1.7.1 Connector/ODBC General Functionality
.............................................

* Menu:

* connector-odbc-usagenotes-functionality-last-insert-id::  Obtaining Auto-Increment Values
* connector-odbc-usagenotes-functionality-dynamic-cursor::  Dynamic Cursor Support
* connector-odbc-usagenotes-functionality-performance::  Connector/ODBC Performance
* connector-odbc-usagenotes-functionality-query-timeout::  Setting ODBC Query Timeout in Windows

This section provides help with common queries and areas of
functionality in MySQL and how to use them with Connector/ODBC.


File: manual.info,  Node: connector-odbc-usagenotes-functionality-last-insert-id,  Next: connector-odbc-usagenotes-functionality-dynamic-cursor,  Prev: connector-odbc-usagenotes-functionality,  Up: connector-odbc-usagenotes-functionality

20.1.7.2 Obtaining Auto-Increment Values
........................................

Obtaining the value of column that uses `AUTO_INCREMENT' after an *Note
`INSERT': insert. statement can be achieved in a number of different
ways. To obtain the value immediately after an *Note `INSERT': insert,
use a *Note `SELECT': select. query with the `LAST_INSERT_ID()'
function.

For example, using Connector/ODBC you would execute two separate
statements, the *Note `INSERT': insert.  statement and the *Note
`SELECT': select. query to obtain the auto-increment value.

     INSERT INTO tbl (auto,text) VALUES(NULL,'text');
     SELECT LAST_INSERT_ID();

If you do not require the value within your application, but do require
the value as part of another *Note `INSERT': insert, the entire process
can be handled by executing the following statements:

     INSERT INTO tbl (auto,text) VALUES(NULL,'text');
     INSERT INTO tbl2 (id,text) VALUES(LAST_INSERT_ID(),'text');

Certain ODBC applications (including Delphi and Access) may have
trouble obtaining the auto-increment value using the previous examples.
In this case, try the following statement as an alternative:

     SELECT * FROM tbl WHERE auto IS NULL;

See *Note getting-unique-id::.


File: manual.info,  Node: connector-odbc-usagenotes-functionality-dynamic-cursor,  Next: connector-odbc-usagenotes-functionality-performance,  Prev: connector-odbc-usagenotes-functionality-last-insert-id,  Up: connector-odbc-usagenotes-functionality

20.1.7.3 Dynamic Cursor Support
...............................

Support for the `dynamic cursor' is provided in Connector/ODBC 3.51,
but dynamic cursors are not enabled by default. You can enable this
function within Windows by selecting the `Enable Dynamic Cursor'
checkbox within the ODBC Data Source Administrator.

On other platforms, you can enable the dynamic cursor by adding `32' to
the `OPTION' value when creating the DSN.


File: manual.info,  Node: connector-odbc-usagenotes-functionality-performance,  Next: connector-odbc-usagenotes-functionality-query-timeout,  Prev: connector-odbc-usagenotes-functionality-dynamic-cursor,  Up: connector-odbc-usagenotes-functionality

20.1.7.4 Connector/ODBC Performance
...................................

The Connector/ODBC driver has been optimized to provide very fast
performance. If you experience problems with the performance of
Connector/ODBC, or notice a large amount of disk activity for simple
queries, there are a number of aspects you should check:

   * Ensure that `ODBC Tracing' is not enabled. With tracing enabled, a
     lot of information is recorded in the tracing file by the ODBC
     Manager. You can check, and disable, tracing within Windows using
     the `Tracing' panel of the ODBC Data Source Administrator. Within
     Mac OS X, check the `Tracing' panel of ODBC Administrator. See
     *Note connector-odbc-configuration-trace::.

   * Make sure you are using the standard version of the driver, and
     not the debug version. The debug version includes additional
     checks and reporting measures.

   * Disable the Connector/ODBC driver trace and query logs.  These
     options are enabled for each DSN, so make sure to examine only the
     DSN that you are using in your application. Within Windows, you
     can disable the Connector/ODBC and query logs by modifying the DSN
     configuration. Within Mac OS X and Unix, ensure that the driver
     trace (option value 4) and query logging (option value 524288) are
     not enabled.


File: manual.info,  Node: connector-odbc-usagenotes-functionality-query-timeout,  Prev: connector-odbc-usagenotes-functionality-performance,  Up: connector-odbc-usagenotes-functionality

20.1.7.5 Setting ODBC Query Timeout in Windows
..............................................

For more information on how to set the query timeout on Microsoft
Windows when executing queries through an ODBC connection, read the
Microsoft knowledgebase document at
`http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B153756'.


File: manual.info,  Node: connector-odbc-usagenotes-apptips,  Next: connector-odbc-errors,  Prev: connector-odbc-usagenotes-functionality,  Up: connector-odbc-usagenotes

20.1.7.6 Connector/ODBC Application Specific Tips
.................................................

* Menu:

* connector-odbc-usagenotes-apptips-microsoft::  Using Connector/ODBC with Microsoft Applications
* connector-odbc-usagenotes-apptips-borland::  Using Connector/ODBC with Borland Applications
* connector-odbc-usagenotes-apptips-coldfusion::  Using Connector/ODBC with ColdFusion
* connector-odbc-usagenotes-apptips-openoffice::  Using Connector/ODBC with OpenOffice.org
* connector-odbc-usagenotes-apptips-sambarserver::  Using Connector/ODBC with Sambar Server
* connector-odbc-usagenotes-apptips-datajunction::  Using Connector/ODBC with Pervasive Software DataJunction
* connector-odbc-usagenotes-apptips-vision::  Using Connector/ODBC with SunSystems Vision

Most programs should work with Connector/ODBC, but for each of those
listed here, there are specific notes and tips to improve or enhance
the way you work with Connector/ODBC and these applications.

With all applications you should ensure that you are using the latest
Connector/ODBC drivers, ODBC Manager and any supporting libraries and
interfaces used by your application. For example, on Windows, using the
latest version of Microsoft Data Access Components (MDAC) will improve
the compatibility with ODBC in general, and with the Connector/ODBC
driver.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-microsoft,  Next: connector-odbc-usagenotes-apptips-borland,  Prev: connector-odbc-usagenotes-apptips,  Up: connector-odbc-usagenotes-apptips

20.1.7.7 Using Connector/ODBC with Microsoft Applications
.........................................................

* Menu:

* connector-odbc-usagenotes-apptips-microsoft-access::  Microsoft Access
* connector-odbc-usagenotes-apptips-microsoft-excel::  Microsoft Excel and Column Types
* connector-odbc-usagenotes-apptips-microsoft-visualbasic::  Microsoft Visual Basic
* connector-odbc-usagenotes-apptips-microsoft-visualinterdev::  Microsoft Visual InterDev
* connector-odbc-usagenotes-apptips-microsoft-visualobjects::  Visual Objects
* connector-odbc-usagenotes-apptips-microsoft-ado::  Microsoft ADO
* connector-odbc-usagenotes-apptips-microsoft-asp::  Using Connector/ODBC with Active Server Pages (ASP)
* connector-odbc-usagenotes-apptips-microsoft-vb-asp::  Using Connector/ODBC with Visual Basic (ADO, DAO and RDO) and ASP

The majority of Microsoft applications have been tested with
Connector/ODBC, including Microsoft Office, Microsoft Access and the
various programming languages supported within ASP and Microsoft Visual
Studio.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-microsoft-access,  Next: connector-odbc-usagenotes-apptips-microsoft-excel,  Prev: connector-odbc-usagenotes-apptips-microsoft,  Up: connector-odbc-usagenotes-apptips-microsoft

20.1.7.8 Microsoft Access
.........................

To improve the integration between Microsoft Access and MySQL through
Connector/ODBC:

   * For all versions of Access, you should enable the Connector/ODBC
     `Return matching rows' option. For Access 2.0, you should
     additionally enable the `Simulate ODBC 1.0' option.

   * You should have a *Note `TIMESTAMP': datetime. column in all
     tables that you want to be able to update. For maximum
     portability, do not use a length specification in the column
     declaration (which is unsupported within MySQL in versions earlier
     than 4.1).

   * You should have a primary key in each MySQL table you want to use
     with Access. If not, new or updated rows may show up as
     `#DELETED#'.

   * Use only *Note `DOUBLE': numeric-types. float fields. Access fails
     when comparing with single-precision floats. The symptom usually
     is that new or updated rows may show up as `#DELETED#' or that you
     cannot find or update rows.

   * If you are using Connector/ODBC to link to a table that has a
     *Note `BIGINT': numeric-types. column, the results are displayed
     as `#DELETED#'.  The work around solution is:

        * Have one more dummy column with *Note `TIMESTAMP': datetime.
          as the data type.

        * Select the `Change BIGINT columns to INT' option in the
          connection dialog in ODBC DSN Administrator.

        * Delete the table link from Access and re-create it.

     Old records may still display as `#DELETED#', but newly
     added/updated records are displayed properly.

   * If you still get the error `Another user has changed your data'
     after adding a *Note `TIMESTAMP': datetime. column, the following
     trick may help you:

     Do not use a `table' data sheet view.  Instead, create a form with
     the fields you want, and use that `form' data sheet view. You
     should set the `DefaultValue' property for the *Note `TIMESTAMP':
     datetime. column to `NOW()'. It may be a good idea to hide the
     *Note `TIMESTAMP': datetime. column from view so your users are
     not confused.

   * In some cases, Access may generate SQL statements that MySQL
     cannot understand. You can fix this by selecting
     `"Query|SQLSpecific|Pass-Through"' from the Access menu.

   * On Windows NT, Access reports *Note `BLOB': blob. columns as `OLE
     OBJECTS'. If you want to have `MEMO' columns instead, you should
     change *Note `BLOB': blob. columns to *Note `TEXT': blob. with
     *Note `ALTER TABLE': alter-table.

   * Access cannot always handle the MySQL *Note `DATE': datetime.
     column properly. If you have a problem with these, change the
     columns to *Note `DATETIME': datetime.

   * If you have in Access a column defined as `BYTE', Access tries to
     export this as *Note `TINYINT': numeric-types. instead of `TINYINT
     UNSIGNED'. This gives you problems if you have values larger than
     127 in the column.

   * If you have very large (long) tables in Access, it might take a
     very long time to open them. Or you might run low on virtual
     memory and eventually get an `ODBC Query Failed' error and the
     table cannot open.  To deal with this, select the following
     options:

        * Return Matching Rows (2)

        * Allow BIG Results (8).

     These add up to a value of 10 (`OPTION=10').

Some external articles and tips that may be useful when using Access,
ODBC and Connector/ODBC:

   * Read How to Trap ODBC Login Error Messages in Access
     (http://support.microsoft.com/support/kb/articles/Q124/9/01.asp?LN=EN-US&SD=gn&FR=0%3CP%3E)

   * Optimizing Access ODBC Applications

        * Optimizing for Client/Server Performance
          (http://support.microsoft.com/default.aspx?scid=kb;en-us;128808)

        * Tips for Converting Applications to Using ODBCDirect
          (http://support.microsoft.com/default.aspx?scid=kb;en-us;164481)

        * Tips for Optimizing Queries on Attached SQL Tables
          (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q99321)

   * For a list of tools that can be used with Access and ODBC data
     sources, refer to converters
     (http://www.mysql.com/portal/software/convertors/) section for
     list of available tools.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about using
ODBC with Access in Knowledge Base articles such as Use MySQL-Specific
Syntax with Microsoft Access (https://kb.mysql.com/view.php?id=5309). To
subscribe to MySQL Enterprise see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-microsoft-excel,  Next: connector-odbc-usagenotes-apptips-microsoft-visualbasic,  Prev: connector-odbc-usagenotes-apptips-microsoft-access,  Up: connector-odbc-usagenotes-apptips-microsoft

20.1.7.9 Microsoft Excel and Column Types
.........................................

If you have problems importing data into Microsoft Excel, particularly
numerical, date, and time values, this is probably because of a bug in
Excel, where the column type of the source data is used to determine
the data type when that data is inserted into a cell within the
worksheet. The result is that Excel incorrectly identifies the content
and this affects both the display format and the data when it is used
within calculations.

To address this issue, use the `CONCAT()' function in your queries. The
use of `CONCAT()' forces Excel to treat the value as a string, which
Excel will then parse and usually correctly identify the embedded
information.

However, even with this option, some data may be incorrectly formatted,
even though the source data remains unchanged.  Use the `Format Cells'
option within Excel to change the format of the displayed information.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-microsoft-visualbasic,  Next: connector-odbc-usagenotes-apptips-microsoft-visualinterdev,  Prev: connector-odbc-usagenotes-apptips-microsoft-excel,  Up: connector-odbc-usagenotes-apptips-microsoft

20.1.7.10 Microsoft Visual Basic
................................

To be able to update a table, you must define a primary key for the
table.

Visual Basic with ADO cannot handle big integers. This means that some
queries like *Note `SHOW PROCESSLIST': show-processlist. do not work
properly. The fix is to use `OPTION=16384' in the ODBC connect string
or to select the `Change BIGINT columns to INT' option in the
Connector/ODBC connect screen.  You may also want to select the `Return
matching rows' option.

MySQL Enterprise

MySQL Enterprise subscribers can find a discussion about using VBA in
the Knowledge Base article, MySQL-Specific Syntax with VBA
(https://kb.mysql.com/view.php?id=5308). To subscribe to MySQL
Enterprise see `http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-microsoft-visualinterdev,  Next: connector-odbc-usagenotes-apptips-microsoft-visualobjects,  Prev: connector-odbc-usagenotes-apptips-microsoft-visualbasic,  Up: connector-odbc-usagenotes-apptips-microsoft

20.1.7.11 Microsoft Visual InterDev
...................................

If you have a *Note `BIGINT': numeric-types. in your result, you may
get the error `[Microsoft][ODBC Driver Manager] Driver does not support
this parameter'. Try selecting the `Change BIGINT columns to INT'
option in the Connector/ODBC connect screen.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-microsoft-visualobjects,  Next: connector-odbc-usagenotes-apptips-microsoft-ado,  Prev: connector-odbc-usagenotes-apptips-microsoft-visualinterdev,  Up: connector-odbc-usagenotes-apptips-microsoft

20.1.7.12 Visual Objects
........................

You should select the `Don't optimize column widths' option.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-microsoft-ado,  Next: connector-odbc-usagenotes-apptips-microsoft-asp,  Prev: connector-odbc-usagenotes-apptips-microsoft-visualobjects,  Up: connector-odbc-usagenotes-apptips-microsoft

20.1.7.13 Microsoft ADO
.......................

When you are coding with the ADO API and Connector/ODBC, you need to
pay attention to some default properties that aren't supported by the
MySQL server. For example, using the `CursorLocation Property' as
`adUseServer' returns a result of -1 for the `RecordCount Property'. To
have the right value, you need to set this property to `adUseClient',
as shown in the VB code here:

     Dim myconn As New ADODB.Connection
     Dim myrs As New Recordset
     Dim mySQL As String
     Dim myrows As Long

     myconn.Open "DSN=MyODBCsample"
     mySQL = "SELECT * from user"
     myrs.Source = mySQL
     Set myrs.ActiveConnection = myconn
     myrs.CursorLocation = adUseClient
     myrs.Open
     myrows = myrs.RecordCount

     myrs.Close
     myconn.Close

Another workaround is to use a `SELECT COUNT(*)' statement for a
similar query to get the correct row count.

To find the number of rows affected by a specific SQL statement in ADO,
use the `RecordsAffected' property in the ADO execute method. For more
information on the usage of execute method, refer to
`http://msdn.microsoft.com/library/default.asp?url=/library/en-us/ado270/htm/mdmthcnnexecute.asp'.

For information, see ActiveX Data Objects(ADO) Frequently Asked
Questions
(http://support.microsoft.com/default.aspx?scid=kb;EN-US;q183606).


File: manual.info,  Node: connector-odbc-usagenotes-apptips-microsoft-asp,  Next: connector-odbc-usagenotes-apptips-microsoft-vb-asp,  Prev: connector-odbc-usagenotes-apptips-microsoft-ado,  Up: connector-odbc-usagenotes-apptips-microsoft

20.1.7.14 Using Connector/ODBC with Active Server Pages (ASP)
.............................................................

You should select the `Return matching rows' option in the DSN.

For more information about how to access MySQL via ASP using
Connector/ODBC, refer to the following articles:

   * Using MyODBC To Access Your MySQL Database Via ASP
     (http://www.devarticles.com/c/a/ASP/Using-MyODBC-To-Access-Your-MySQL-Database-Via-ASP/)

   * ASP and MySQL at DWAM.NT (http://www.dwam.net/mysql/asp_myodbc.asp)

A Frequently Asked Questions list for ASP can be found at
`http://support.microsoft.com/default.aspx?scid=/Support/ActiveServer/faq/data/adofaq.asp'.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-microsoft-vb-asp,  Prev: connector-odbc-usagenotes-apptips-microsoft-asp,  Up: connector-odbc-usagenotes-apptips-microsoft

20.1.7.15 Using Connector/ODBC with Visual Basic (ADO, DAO and RDO) and ASP
...........................................................................

Some articles that may help with Visual Basic and ASP:

   * MySQL BLOB columns and Visual Basic 6
     (http://dev.mysql.com/tech-resources/articles/vb-blob-handling.html)
     by Mike Hillyer (<mike@openwin.org>).

   * How to map Visual basic data type to MySQL types
     (http://dev.mysql.com/tech-resources/articles/visual-basic-datatypes.html)
     by Mike Hillyer (<mike@openwin.org>).


File: manual.info,  Node: connector-odbc-usagenotes-apptips-borland,  Next: connector-odbc-usagenotes-apptips-coldfusion,  Prev: connector-odbc-usagenotes-apptips-microsoft,  Up: connector-odbc-usagenotes-apptips

20.1.7.16 Using Connector/ODBC with Borland Applications
........................................................

* Menu:

* connector-odbc-usagenotes-apptips-borland-builder::  Using Connector/ODBC with Borland Builder 4
* connector-odbc-usagenotes-apptips-borland-delphi::  Using Connector/ODBC with Delphi
* connector-odbc-usagenotes-apptips-borland-cppbuilder::  Using Connector/ODBC with C++ Builder

With all Borland applications where the Borland Database Engine (BDE)
is used, follow these steps to improve compatibility:

   * Update to BDE 3.2 or newer.

   * Enable the `Don't optimize column widths' option in the DSN.

   * Enabled the `Return matching rows' option in the DSN.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-borland-builder,  Next: connector-odbc-usagenotes-apptips-borland-delphi,  Prev: connector-odbc-usagenotes-apptips-borland,  Up: connector-odbc-usagenotes-apptips-borland

20.1.7.17 Using Connector/ODBC with Borland Builder 4
.....................................................

When you start a query, you can use the `Active' property or the `Open'
method. Note that `Active' starts by automatically issuing a `SELECT *
FROM ...' query. That may not be a good thing if your tables are large.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-borland-delphi,  Next: connector-odbc-usagenotes-apptips-borland-cppbuilder,  Prev: connector-odbc-usagenotes-apptips-borland-builder,  Up: connector-odbc-usagenotes-apptips-borland

20.1.7.18 Using Connector/ODBC with Delphi
..........................................

Also, here is some potentially useful Delphi code that sets up both an
ODBC entry and a BDE entry for Connector/ODBC.  The BDE entry requires
a BDE Alias Editor that is free at a Delphi Super Page near you.
(Thanks to Bryan Brunton <bryan@flesherfab.com> for this):

     fReg:= TRegistry.Create;
     fReg.OpenKey('\Software\ODBC\ODBC.INI\DocumentsFab', True);
     fReg.WriteString('Database', 'Documents');
     fReg.WriteString('Description', ' ');
     fReg.WriteString('Driver', 'C:\WINNT\System32\myodbc.dll');
     fReg.WriteString('Flag', '1');
     fReg.WriteString('Password', '');
     fReg.WriteString('Port', ' ');
     fReg.WriteString('Server', 'xmark');
     fReg.WriteString('User', 'winuser');
     fReg.OpenKey('\Software\ODBC\ODBC.INI\ODBC Data Sources', True);
     fReg.WriteString('DocumentsFab', 'MySQL');
     fReg.CloseKey;
     fReg.Free;

     Memo1.Lines.Add('DATABASE NAME=');
     Memo1.Lines.Add('USER NAME=');
     Memo1.Lines.Add('ODBC DSN=DocumentsFab');
     Memo1.Lines.Add('OPEN MODE=READ/WRITE');
     Memo1.Lines.Add('BATCH COUNT=200');
     Memo1.Lines.Add('LANGDRIVER=');
     Memo1.Lines.Add('MAX ROWS=-1');
     Memo1.Lines.Add('SCHEMA CACHE DIR=');
     Memo1.Lines.Add('SCHEMA CACHE SIZE=8');
     Memo1.Lines.Add('SCHEMA CACHE TIME=-1');
     Memo1.Lines.Add('SQLPASSTHRU MODE=SHARED AUTOCOMMIT');
     Memo1.Lines.Add('SQLQRYMODE=');
     Memo1.Lines.Add('ENABLE SCHEMA CACHE=FALSE');
     Memo1.Lines.Add('ENABLE BCD=FALSE');
     Memo1.Lines.Add('ROWSET SIZE=20');
     Memo1.Lines.Add('BLOBS TO CACHE=64');
     Memo1.Lines.Add('BLOB SIZE=32');

     AliasEditor.Add('DocumentsFab','MySQL',Memo1.Lines);


File: manual.info,  Node: connector-odbc-usagenotes-apptips-borland-cppbuilder,  Prev: connector-odbc-usagenotes-apptips-borland-delphi,  Up: connector-odbc-usagenotes-apptips-borland

20.1.7.19 Using Connector/ODBC with C++ Builder
...............................................

Tested with BDE 3.0. The only known problem is that when the table
schema changes, query fields are not updated. BDE, however, does not
seem to recognize primary keys, only the index named `PRIMARY',
although this has not been a problem.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-coldfusion,  Next: connector-odbc-usagenotes-apptips-openoffice,  Prev: connector-odbc-usagenotes-apptips-borland,  Up: connector-odbc-usagenotes-apptips

20.1.7.20 Using Connector/ODBC with ColdFusion
..............................................

The following information is taken from the ColdFusion documentation:

Use the following information to configure ColdFusion Server for Linux
to use the `unixODBC' driver with Connector/ODBC for MySQL data
sources. You can download Connector/ODBC at
`http://dev.mysql.com/downloads/connector/odbc/'.

ColdFusion version 4.5.1 allows you to us the ColdFusion Administrator
to add the MySQL data source. However, the driver is not included with
ColdFusion version 4.5.1. Before the MySQL driver appears in the ODBC
data sources drop-down list, you must build and copy the Connector/ODBC
driver to `/opt/coldfusion/lib/libmyodbc.so'.

The Contrib directory contains the program `mydsn-XXX.zip' which allows
you to build and remove the DSN registry file for the Connector/ODBC
driver on ColdFusion applications.

For more information and guides on using ColdFusion and Connector/ODBC,
see the following external sites:

   * Troubleshooting Data Sources and Database Connectivity for Unix
     Platforms
     (http://www.macromedia.com/v1/handlers/index.cfm?ID=11328&Method=Full&PageCall=/support/index.cfm).


File: manual.info,  Node: connector-odbc-usagenotes-apptips-openoffice,  Next: connector-odbc-usagenotes-apptips-sambarserver,  Prev: connector-odbc-usagenotes-apptips-coldfusion,  Up: connector-odbc-usagenotes-apptips

20.1.7.21 Using Connector/ODBC with OpenOffice.org
..................................................

Open Office (`http://www.openoffice.org') How-to: MySQL + OpenOffice
(http://wiki.services.openoffice.org/wiki/Connect_MySQL_and_Base).
How-to: OpenOffice + MyODBC + unixODBC
(http://www.unixodbc.org/doc/OOoMySQL.pdf).


File: manual.info,  Node: connector-odbc-usagenotes-apptips-sambarserver,  Next: connector-odbc-usagenotes-apptips-datajunction,  Prev: connector-odbc-usagenotes-apptips-openoffice,  Up: connector-odbc-usagenotes-apptips

20.1.7.22 Using Connector/ODBC with Sambar Server
.................................................

Sambar Server (`http://www.sambarserver.info') How-to: MyODBC +
SambarServer + MySQL (http://www.sambarserver.info/article.php?sid=66).


File: manual.info,  Node: connector-odbc-usagenotes-apptips-datajunction,  Next: connector-odbc-usagenotes-apptips-vision,  Prev: connector-odbc-usagenotes-apptips-sambarserver,  Up: connector-odbc-usagenotes-apptips

20.1.7.23 Using Connector/ODBC with Pervasive Software DataJunction
...................................................................

You have to change it to output *Note `VARCHAR': char. rather than
*Note `ENUM': enum, as it exports the latter in a manner that causes
MySQL problems.


File: manual.info,  Node: connector-odbc-usagenotes-apptips-vision,  Prev: connector-odbc-usagenotes-apptips-datajunction,  Up: connector-odbc-usagenotes-apptips

20.1.7.24 Using Connector/ODBC with SunSystems Vision
.....................................................

You should select the `Return matching rows' option.


File: manual.info,  Node: connector-odbc-errors,  Prev: connector-odbc-usagenotes-apptips,  Up: connector-odbc-usagenotes

20.1.7.25 Connector/ODBC Errors and Resolutions (FAQ)
.....................................................

The following section details some common errors and their suggested
fix or alternative solution. If you are still experiencing problems,
use the Connector/ODBC mailing list; see *Note
connector-odbc-support-community::.

Many problems can be resolved by upgrading your Connector/ODBC drivers
to the latest available release. On Windows, you should also make sure
that you have the latest versions of the Microsoft Data Access
Components (MDAC) installed.

*Questions*
   * 20.1.7.3.1: I have installed Connector/ODBC on Windows XP x64
     Edition or Windows Server 2003 R2 x64. The installation completed
     successfully, but the Connector/ODBC driver does not appear in
     `ODBC Data Source Administrator'.

   * 20.1.7.3.2: When connecting or using the `Test' button in `ODBC
     Data Source Administrator' I get error 10061 (Cannot connect to
     server)

   * 20.1.7.3.3: The following error is reported when using
     transactions: `Transactions are not enabled'

   * 20.1.7.3.4: Access reports records as `#DELETED#' when inserting
     or updating records in linked tables.

   * 20.1.7.3.5: How do I handle Write Conflicts or Row Location errors?

   * 20.1.7.3.6: Exporting data from Access 97 to MySQL reports a
     `Syntax Error'.

   * 20.1.7.3.7: Exporting data from Microsoft DTS to MySQL reports a
     `Syntax Error'.

   * 20.1.7.3.8: Using ODBC.NET with Connector/ODBC, while fetching
     empty string (0 length), it starts giving the SQL_NO_DATA
     exception.

   * 20.1.7.3.9: Using `SELECT COUNT(*) FROM TBL_NAME' within Visual
     Basic and ASP returns an error.

   * 20.1.7.3.10: Using the `AppendChunk()' or `GetChunk()' ADO
     methods, the `Multiple-step operation generated errors. Check each
     status value' error is returned.

   * 20.1.7.3.11: Access Returns `Another user had modified the record
     that you have modified' while editing records on a Linked Table.

   * 20.1.7.3.12: When linking an application directly to the
     Connector/ODBC library under Unix/Linux, the application crashes.

   * 20.1.7.3.13: Applications in the Microsoft Office suite are unable
     to update tables that have *Note `DATE': datetime. or *Note
     `TIMESTAMP': datetime. columns.

   * 20.1.7.3.14: When connecting Connector/ODBC 5.x (Beta) to a MySQL
     4.x server, the error `1044 Access denied for user 'xxx'@'%' to
     database 'information_schema'' is returned.

   * 20.1.7.3.15: When calling `SQLTables', the error `S1T00' is
     returned, but I cannot find this in the list of error numbers for
     Connector/ODBC.

   * 20.1.7.3.16: When linking to tables in Access 2000 and generating
     links to tables programmatically, rather than through the table
     designer interface, you may get errors about tables not existing.

   * 20.1.7.3.17: When I try to use batched statements, the excution of
     the batched statements fails.

   * 20.1.7.3.18: When connecting to a MySQL server using ADODB and
     Excel, occasionally the application fails to communicate with the
     server and the error `Got an error reading communication packets'
     appears in the error log.

   * 20.1.7.3.19: When using some applications to access a MySQL server
     using C/ODBC and outer joins, an error is reported regarding the
     Outer Join Escape Sequence.

   * 20.1.7.3.20: I can correctly store extended characters in the
     database (Hebrew/CJK) using C/ODBC 5.1, but when I retrieve the
     data, the text is not formatted correctly and I get garbled
     characters.

   * 20.1.7.3.21: I have a duplicate MySQL Connector/ODBC entry within
     my `Installed Programs' list, but I cannot delete one of them.

   * 20.1.7.3.22: When submitting queries with parameter binding using
     *Note `UPDATE': update, my field values are being truncated to 255
     characters.

   * 20.1.7.3.23: Is it possible to disable data-at-execution using a
     flag?

*Questions and Answers* *20.1.7.3.1: ** I have installed Connector/ODBC
on Windows XP x64 Edition or Windows Server 2003 R2 x64. The
installation completed successfully, but the Connector/ODBC driver does
not appear in `ODBC Data Source Administrator'.  *

This is not a bug, but is related to the way Windows x64 editions
operate with the ODBC driver. On Windows x64 editions, the
Connector/ODBC driver is installed in the `%SystemRoot%\SysWOW64'
folder.  However, the default `ODBC Data Source Administrator' that is
available through the `Administrative Tools' or `Control Panel' in
Windows x64 Editions is located in the `%SystemRoot%\system32' folder,
and only searches this folder for ODBC drivers.

On Windows x64 editions, you should use the ODBC administration tool
located at `%SystemRoot%\SysWOW64\odbcad32.exe', this will correctly
locate the installed Connector/ODBC drivers and enable you to create a
Connector/ODBC DSN.

This issue was originally reported as Bug#20301
(http://bugs.mysql.com/20301).

*20.1.7.3.2: ** When connecting or using the `Test' button in `ODBC
Data Source Administrator' I get error 10061 (Cannot connect to server)
*

This error can be raised by a number of different issues, including
server problems, network problems, and firewall and port blocking
problems. For more information, see *Note can-not-connect-to-server::.

*20.1.7.3.3: ** The following error is reported when using transactions:
`Transactions are not enabled' *

This error indicates that you are trying to use transactions with a
MySQL table that does not support transactions. Transactions are
supported within MySQL when using the `InnoDB' database engine. In
versions of MySQL before Mysql 5.1 you may also use the `BDB' engine.

You should check the following before continuing:

   * Verify that your MySQL server supports a transactional database
     engine. Use *Note `SHOW ENGINES': show-engines. to obtain a list
     of the available engine types.

   * Verify that the tables you are updating use a transaction database
     engine.

   * Ensure that you have not enabled the `disable transactions' option
     in your DSN.

*20.1.7.3.4: ** Access reports records as `#DELETED#' when inserting or
updating records in linked tables.  *

If the inserted or updated records are shown as `#DELETED#' in the
access, then:

   * If you are using Access 2000, you should get and install the
     newest (version 2.6 or higher) Microsoft MDAC (`Microsoft Data
     Access Components') from `http://support.microsoft.com/kb/110093'.
     This fixes a bug in Access that when you export data to MySQL, the
     table and column names aren't specified.

     You should also get and apply the Microsoft Jet 4.0 Service Pack 5
     (SP5) which can be found at
     `http://support.microsoft.com/default.aspx?scid=kb;EN-US;q239114'.
     This fixes some cases where columns are marked as `#DELETED#' in
     Access.

   * For all versions of Access, you should enable the Connector/ODBC
     `Return matching rows' option. For Access 2.0, you should
     additionally enable the `Simulate ODBC 1.0' option.

   * You should have a timestamp in all tables that you want to be able
     to update.

   * You should have a primary key in the table. If not, new or updated
     rows may show up as `#DELETED#'.

   * Use only *Note `DOUBLE': numeric-types. float fields. Access fails
     when comparing with single-precision floats. The symptom usually
     is that new or updated rows may show up as `#DELETED#' or that you
     cannot find or update rows.

   * If you are using Connector/ODBC to link to a table that has a
     *Note `BIGINT': numeric-types.  column, the results are displayed
     as `#DELETED'. The work around solution is:

        * Have one more dummy column with *Note `TIMESTAMP': datetime.
          as the data type.

        * Select the `Change BIGINT columns to INT' option in the
          connection dialog in ODBC DSN Administrator.

        * Delete the table link from Access and re-create it.

     Old records still display as `#DELETED#', but newly added/updated
     records are displayed properly.

*20.1.7.3.5: ** How do I handle Write Conflicts or Row Location errors?
*

If you see the following errors, select the `Return Matching Rows'
option in the DSN configuration dialog, or specify `OPTION=2', as the
connection parameter:

     Write Conflict. Another user has changed your data.

     Row cannot be located for updating. Some values may have been changed
     since it was last read.

*20.1.7.3.6: ** Exporting data from Access 97 to MySQL reports a
`Syntax Error'.  *

This error is specific to Access 97 and versions of Connector/ODBC
earlier than 3.51.02. Update to the latest version of the
Connector/ODBC driver to resolve this problem.

*20.1.7.3.7: ** Exporting data from Microsoft DTS to MySQL reports a
`Syntax Error'.  *

This error occurs only with MySQL tables using the *Note `TEXT': blob.
or *Note `VARCHAR': char. data types. You can fix this error by
upgrading your Connector/ODBC driver to version 3.51.02 or higher.

*20.1.7.3.8: ** Using ODBC.NET with Connector/ODBC, while fetching empty
string (0 length), it starts giving the SQL_NO_DATA exception.  *

You can get the patch that addresses this problem from
`http://support.microsoft.com/default.aspx?scid=kb;EN-US;q319243'.

*20.1.7.3.9: ** Using `SELECT COUNT(*) FROM TBL_NAME' within Visual
Basic and ASP returns an error.  *

This error occurs because the `COUNT(*)' expression is returning a
*Note `BIGINT': numeric-types, and ADO cannot make sense of a number
this big. Select the `Change BIGINT columns to INT' option (option
value 16384).

*20.1.7.3.10: ** Using the `AppendChunk()' or `GetChunk()' ADO methods,
the `Multiple-step operation generated errors. Check each status value'
error is returned.  *

The `GetChunk()' and `AppendChunk()' methods from ADO doesn't work as
expected when the cursor location is specified as `adUseServer'. On the
other hand, you can overcome this error by using `adUseClient'.

A simple example can be found from
`http://www.dwam.net/iishelp/ado/docs/adomth02_4.htm'

*20.1.7.3.11: ** Access Returns `Another user had modified the record
that you have modified' while editing records on a Linked Table.  *

In most cases, this can be solved by doing one of the following things:

   * Add a primary key for the table if one doesn't exist.

   * Add a timestamp column if one doesn't exist.

   * Only use double-precision float fields. Some programs may fail
     when they compare single-precision floats.

If these strategies do not help, you should start by making a log file
from the ODBC manager (the log you get when requesting logs from
ODBCADMIN) and a Connector/ODBC log to help you figure out why things
go wrong. For instructions, see *Note
connector-odbc-configuration-trace::.

*20.1.7.3.12: ** When linking an application directly to the
Connector/ODBC library under Unix/Linux, the application crashes.  *

Connector/ODBC 3.51 under Unix/Linux is not compatible with direct
application linking. You must use a driver manager, such as iODBC or
unixODBC to connect to an ODBC source.

*20.1.7.3.13: ** Applications in the Microsoft Office suite are unable
to update tables that have *Note `DATE': datetime. or *Note
`TIMESTAMP': datetime. columns.  *

This is a known issue with Connector/ODBC. You must ensure that the
field has a default value (rather than `NULL' and that the default
value is non-zeo (i.e. the default value is not `0000-00-00 00:00:00').

*20.1.7.3.14: ** When connecting Connector/ODBC 5.x (Beta) to a MySQL
4.x server, the error `1044 Access denied for user 'xxx'@'%' to
database 'information_schema'' is returned.  *

Connector/ODBC 5.x is designed to work with MySQL 5.0 or later, taking
advantage of the `INFORMATION_SCHEMA' database to determine data
definition information. Support for MySQL 4.1 is planned for the final
release.

*20.1.7.3.15: ** When calling `SQLTables', the error `S1T00' is
returned, but I cannot find this in the list of error numbers for
Connector/ODBC.  *

The `S1T00' error indicates that a general timeout has occurred within
the ODBC system and is not a MySQL error. Typically it indicates that
the connection you are using is stale, the server is too busy to accept
your request or that the server has gone away.

*20.1.7.3.16: ** When linking to tables in Access 2000 and generating
links to tables programmatically, rather than through the table
designer interface, you may get errors about tables not existing.  *

There is a known issue with a specific version of the `msjet40.dll'
that exhibits this issue.  The version affected is 4.0.9025.0.
Reverting to an older version will enable you to create the links. If
you have recently updated your version, check your `WINDOWS' directory
for the older version of the file and copy it to the drivers directory.

*20.1.7.3.17: ** When I try to use batched statements, the excution of
the batched statements fails.  *

Batched statement support was added in 3.51.18. Support for batched
statements is not enabled by default. You must enable option
`FLAG_MULTI_STATEMENTS', value 67108864, or select the `Allow multiple
statements' flag within a GUI configuration.

*20.1.7.3.18: ** When connecting to a MySQL server using ADODB and
Excel, occasionally the application fails to communicate with the
server and the error `Got an error reading communication packets'
appears in the error log.  *

This error may be related to Keyboard Logger 1.1 from PanteraSoft.com,
which is known to interfere with the network communication between
MySQL Connector/ODBC and MySQL.

*20.1.7.3.19: ** When using some applications to access a MySQL server
using C/ODBC and outer joins, an error is reported regarding the Outer
Join Escape Sequence.  *

This is a known issue with MySQL Connector/ODBC which is not correctly
parsing the "Outer Join Escape Sequence", as per the specs at Microsoft
ODBC Specs (http://msdn2.microsoft.com/en-us/library/ms710299.aspx).
Currently, Connector/ODBC will return value > 0 when asked for
`SQL_OJ_CAPABILITIES' even though no parsing takes place in the driver
to handle the outer join escape sequence.

*20.1.7.3.20: ** I can correctly store extended characters in the
database (Hebrew/CJK) using C/ODBC 5.1, but when I retrieve the data,
the text is not formatted correctly and I get garbled characters.  *

When using ASP and UTF8 characters you should add the following to your
ASP files to ensure that the data returned is correctly encoded:

     Response.CodePage = 65001
     Response.CharSet = "utf-8"

*20.1.7.3.21: ** I have a duplicate MySQL Connector/ODBC entry within my
`Installed Programs' list, but I cannot delete one of them.  *

This problem can occur when you upgrade an existing Connector/ODBC
installation, rather than removing and then installing the updated
version.

*Warning*:

To fix the problem you should use any working uninstallers to remove
existing installations and then may have to edit the contents of the
registry. Make sure you have a backup of your registry information
before attempting any editing of the registry contents.

*20.1.7.3.22: ** When submitting queries with parameter binding using
*Note `UPDATE': update, my field values are being truncated to 255
characters.  *

You should ensure that the `FLAG_BIG_PACKETS' option is set for your
connection. This removes the 255 character limitation on bound
parameters.

*20.1.7.3.23: ** Is it possible to disable data-at-execution using a
flag?  *

If you do not wish to use data-at-execution, simply remove the
corresponding calls. For example:

     SQLLEN ylen = SQL_LEN_DATA_AT_EXEC(10);
     SQLBindCol(hstmt,2,SQL_C_BINARY, buf, 10, &ylen);

Would become:

     SQLBindCol(hstmt,2,SQL_C_BINARY, buf, 10, NULL);

Note that in the call to `SQLBindCol()', &ylen has been replaced by
NULL.

For further information please refer to the MSDN documentation
(http://msdn.microsoft.com/en-us/library/ms711010(VS.85).aspx) for
`SQLBindCol()'.


File: manual.info,  Node: connector-odbc-support,  Prev: connector-odbc-usagenotes,  Up: connector-odbc

20.1.8 Connector/ODBC Support
-----------------------------

* Menu:

* connector-odbc-support-community::  Connector/ODBC Community Support
* connector-odbc-support-bug-report::  How to Report Connector/ODBC Problems or Bugs
* connector-odbc-support-patch-submission::  How to Submit a Connector/ODBC Patch
* connector-odbc-support-changehistory::  Connector/ODBC Change History
* connector-odbc-support-credits::  Credits

There are many different places where you can get support for using
Connector/ODBC. You should always try the Connector/ODBC Mailing List
or Connector/ODBC Forum. See *Note connector-odbc-support-community::,
for help before reporting a specific bug or issue to MySQL.


File: manual.info,  Node: connector-odbc-support-community,  Next: connector-odbc-support-bug-report,  Prev: connector-odbc-support,  Up: connector-odbc-support

20.1.8.1 Connector/ODBC Community Support
.........................................

Sun Microsystems, Inc. provides assistance to the user community by
means of its mailing lists. For Connector/ODBC-related issues, you can
get help from experienced users by using the <myodbc@lists.mysql.com>
mailing list. Archives are available online at
`http://lists.mysql.com/myodbc'.

For information about subscribing to MySQL mailing lists or to browse
list archives, visit `http://lists.mysql.com/'. See *Note
mailing-lists::.

Community support from experienced users is also available through the
ODBC Forum (http://forums.mysql.com/list.php?37). You may also find
help from other users in the other MySQL Forums, located at
`http://forums.mysql.com'. See *Note forums::.


File: manual.info,  Node: connector-odbc-support-bug-report,  Next: connector-odbc-support-patch-submission,  Prev: connector-odbc-support-community,  Up: connector-odbc-support

20.1.8.2 How to Report Connector/ODBC Problems or Bugs
......................................................

If you encounter difficulties or problems with Connector/ODBC, you
should start by making a log file from the `ODBC Manager' (the log you
get when requesting logs from `ODBC ADMIN') and Connector/ODBC. The
procedure for doing this is described in *Note
connector-odbc-configuration-trace::.

Check the Connector/ODBC trace file to find out what could be wrong.
You should be able to determine what statements were issued by
searching for the string `>mysql_real_query' in the `myodbc.log' file.

You should also try issuing the statements from the *Note `mysql':
mysql. client program or from `admndemo'. This helps you determine
whether the error is in Connector/ODBC or MySQL.

If you find out something is wrong, please only send the relevant rows
(maximum 40 rows) to the `myodbc' mailing list. See *Note
mailing-lists::. Please never send the whole Connector/ODBC or ODBC log
file!

You should ideally include the following information with the email:

   * Operating system and version

   * Connector/ODBC version

   * ODBC Driver Manager type and version

   * MySQL server version

   * ODBC trace from Driver Manager

   * Connector/ODBC log file from Connector/ODBC driver

   * Simple reproducible sample

Remember that the more information you can supply to us, the more
likely it is that we can fix the problem!

Also, before posting the bug, check the MyODBC mailing list archive at
`http://lists.mysql.com/myodbc'.

If you are unable to find out what is wrong, the last option is to
create an archive in `tar' or Zip format that contains a Connector/ODBC
trace file, the ODBC log file, and a `README' file that explains the
problem. You can send this to `ftp://ftp.mysql.com/pub/mysql/upload/'.
Only MySQL engineers have access to the files you upload, and we are
very discreet with the data.

If you can create a program that also demonstrates the problem, please
include it in the archive as well.

If the program works with another SQL server, you should include an
ODBC log file where you perform exactly the same SQL statements so that
we can compare the results between the two systems.

Remember that the more information you can supply to us, the more
likely it is that we can fix the problem.


File: manual.info,  Node: connector-odbc-support-patch-submission,  Next: connector-odbc-support-changehistory,  Prev: connector-odbc-support-bug-report,  Up: connector-odbc-support

20.1.8.3 How to Submit a Connector/ODBC Patch
.............................................

You can send a patch or suggest a better solution for any existing code
or problems by sending a mail message to <myodbc@lists.mysql.com>.


File: manual.info,  Node: connector-odbc-support-changehistory,  Next: connector-odbc-support-credits,  Prev: connector-odbc-support-patch-submission,  Up: connector-odbc-support

20.1.8.4 Connector/ODBC Change History
......................................

The Connector/ODBC Change History (Changelog) is located with the main
Changelog for MySQL. See *Note connector-odbc-news::.


File: manual.info,  Node: connector-odbc-support-credits,  Prev: connector-odbc-support-changehistory,  Up: connector-odbc-support

20.1.8.5 Credits
................

These are the developers that have worked on the Connector/ODBC and
Connector/ODBC 3.51 Drivers from MySQL AB.

   * Michael (Monty) Widenius

   * Venu Anuganti

   * Peter Harvey


File: manual.info,  Node: connector-net,  Next: connector-vstudio,  Prev: connector-odbc,  Up: connectors-apis

20.2 MySQL Connector/NET
========================

* Menu:

* connector-net-versions::       Connector/NET Versions
* connector-net-installation::   Connector/NET Installation
* connector-net-examples::       Connector/NET Examples and Usage Guide
* connector-net-ref::            Connector/NET Reference
* connector-net-using::          Connector/NET Notes and Tips
* connect-net-support::          Connector/NET Support

Connector/NET enables developers to easily create .NET applications
that require secure, high-performance data connectivity with MySQL.  It
implements the required ADO.NET interfaces and integrates into ADO.NET
aware tools. Developers can build applications using their choice of
.NET languages. Connector/NET is a fully managed ADO.NET driver written
in 100% pure C#.

Connector/NET includes full support for:

   * MySQL 6.0 features

   * MySQL 5.1 features

   * MySQL 5.0 features (such as stored procedures)

   * MySQL 4.1 features (server-side prepared statements, Unicode, and
     shared memory access, and so forth)

   * Large-packet support for sending and receiving rows and BLOBs up
     to 2 gigabytes in size.

   * Protocol compression which allows for compressing the data stream
     between the client and server.

   * Support for connecting using TCP/IP sockets, named pipes, or
     shared memory on Windows.

   * Support for connecting using TCP/IP sockets or Unix sockets on
     Unix.

   * Support for the Open Source Mono framework developed by Novell.

   * Fully managed, does not utilize the MySQL client library.

This document is intended as a user's guide to Connector/NET and
includes a full syntax reference. Syntax information is also included
within the `Documentation.chm' file included with the Connector/NET
distribution.

If you are using MySQL 5.0 or later, and Visual Studio as your
development environment, you may want also want to use the MySQL Visual
Studio Plugin. The plugin acts as a DDEX (Data Designer Extensibility)
provider, enabling you to use the data design tools within Visual
Studio to manipulate the schema and objects within a MySQL database.
For more information, see *Note connector-vstudio::.

*Note*:

Connector/NET 5.1.2 and later include the Visual Studio Plugin by
default.

*Key topics:*

   * For connection string properties when using the MySqlConnection
     class, see *Note
     connector-net-examples-mysqlconnection-connectionstring::.


File: manual.info,  Node: connector-net-versions,  Next: connector-net-installation,  Prev: connector-net,  Up: connector-net

20.2.1 Connector/NET Versions
-----------------------------

There are several versions of Connector/NET available:

   * Connector/NET 1.0 includes support for MySQL 4.0, and MySQL 5.0
     features, and full compatibility with the ADO.NET driver interface.

   * Connector/NET 5.0 includes support for MySQL 4.0, MySQL 4.1, MySQL
     5.0 and MySQL 5.1 features. Connector/NET 5.0 also includes full
     support for the ADO.Net 2.0 interfaces and subclasses, includes
     support for the usage advisor and performance monitor (PerfMon)
     hooks.

   * Connector/NET 5.1 includes support for MySQL 4.0, MySQL 5.0, MySQL
     5.1 and MySQL 6.0 (Falcon Preview) features.  Connector/NET 5.1
     also includes support for a new membership/role provider, Compact
     Framework 2.0, a new stored procedure parser and improvements to
     `GetSchema'. Connector/NET 5.1 also includes the Visual Studio
     Plugin as a standard installable component.

   * Connector/NET 5.2 includes support for MySQL 4.0, MySQL 5.0, MySQL
     5.1 and MySQL 6.0 (Falcon Preview) features.  Connector/NET 5.2
     also includes support for a new membership/role provider, Compact
     Framework 2.0, a new stored procedure parser and improvements to
     `GetSchema'. Connector/NET 5.2 also includes the Visual Studio
     Plugin as a standard installable component.

   * Connector/NET 6.0 includes support for MySQL 4.0, MySQL 5.0, MySQL
     5.1 and MySQL 6.0. Connector/NET 6.0 is currently available as an
     Alpha release.

The latest source code for Connector/NET can be downloaded from the
MySQL public Subversion server. For further details see *Note
connector-net-installation-source::.

The following table shows the .NET Framework version required, and
MySQL Server version supported by Connector/NET:

*Connector/NET     *ADO.NET version   *.NET Framework    *MySQL Server
version*           supported*         version required*  version supported*
1.0                1.x                1.x                4.0, 5.0
5.0                1.x+               1.x+               4.0, 5.0
5.1                1.x+               1.x+               4.0, 5.0, 5.1, 6.0
5.2                1.x+               1.x+               4.0, 5.0, 5.1, 6.0
6.0                2.x+               2.x+               4.0, 5.0, 5.1, 6.0

*Note*:

Version numbers for MySQL products are formatted as X.X.X.  However,
Windows tools (Control Panel, properties display) may show the version
numbers as XX.XX.XX. For example, the official MySQL formatted version
number 5.0.9 may be displayed by Windows tools as 5.00.09. The two
versions are the same; only the number display format is different.


File: manual.info,  Node: connector-net-installation,  Next: connector-net-examples,  Prev: connector-net-versions,  Up: connector-net

20.2.2 Connector/NET Installation
---------------------------------

* Menu:

* connector-net-installation-windows::  Installing Connector/NET on Windows
* connector-net-installation-unix::  Installing Connector/NET on Unix with Mono
* connector-net-installation-source::  Installing Connector/NET from the source code

Connector/NET runs on any platform that supports the .NET framework.
The .NET framework is primarily supported on recent versions of
Microsoft Windows, and is supported on Linux through the Open Source
Mono framework (see `http://www.mono-project.com').

Connector/NET is available for download from
`http://dev.mysql.com/downloads/connector/net/5.2.html'.


File: manual.info,  Node: connector-net-installation-windows,  Next: connector-net-installation-unix,  Prev: connector-net-installation,  Up: connector-net-installation

20.2.2.1 Installing Connector/NET on Windows
............................................

* Menu:

* connector-net-installation-binary-windows-installer::  Installing Connector/NET using the Installer
* connector-net-installation-binary-windows-zip::  Installing Connector/NET using the Zip packages

On Windows, installation is supported either through a binary
installation process or by downloading a Zip file with the
Connector/NET components.

Before installing, you should ensure that your system is up to date,
including installing the latest version of the .NET Framework.


File: manual.info,  Node: connector-net-installation-binary-windows-installer,  Next: connector-net-installation-binary-windows-zip,  Prev: connector-net-installation-windows,  Up: connector-net-installation-windows

20.2.2.2 Installing Connector/NET using the Installer
.....................................................

Using the installer is the most straightforward method of installing
Connector/NET on Windows and the installed components include the
source code, test code and full reference documentation.

Connector/NET is installed through the use of a Windows Installer
(`.msi') installation package, which can be used to install
Connector/NET on all Windows operating systems. The MSI package in
contained within a ZIP archive named `mysql-connector-net-VERSION.zip',
where VERSION indicates the Connector/NET version.

To install Connector/NET:

  1. Double click on the MSI installer file extracted from the Zip you
     downloaded. Click `Next' to start the installation.

     Connector/NET Windows Installer - Welcome

  2. You must choose the type of installation that you want to perform.

     Connector/NET Windows Installer - Installation type

     For most situations, the Typical installation will be suitable.
     Click the `Typical' button and proceed to Step 5. A Complete
     installation installs all the available files. To conduct a
     Complete installation, click the `Complete' button and proceed to
     step 5. If you want to customize your installation, including
     choosing the components to install and some installation options,
     click the `Custom' button and proceed to Step 3.

     The Connector/NET installer will register the connector within the
     Global Assembly Cache (GAC) - this will make the Connector/NET
     component available to all applications, not just those where you
     explicitly reference the Connector/NET component. The installer
     will also create the necessary links in the Start menu to the
     documentation and release notes.

  3. If you have chosen a custom installation, you can select the
     individual components that you want to install, including the core
     interface component, supporting documentation (a CHM file) samples
     and examples and the source code. Select the items, and their
     installation level, and then click `Next' to continue the
     installation.

     *Note*:

     For Connector/NET 1.0.8 or lower and Connector 5.0.4 and lower the
     installer will attempt to install binaries for both 1.x and 2.x of
     the .NET Framework. If you only have one version of the framework
     installed, the connector installation may fail. If this happens,
     you can choose the framework version to be installed through the
     custom installation step.

     Connector/NET Windows Installer - Custom setup

  4. You will be given a final opportunity to confirm the installation.
     Click `Install' to copy and install the files onto your machine.

     Connector/NET Windows Installer - Confirming installation

  5. Once the installation has been completed, click `Finish' to exit
     the installer.

     Connector/NET Windows Installer - Finish installation

Unless you choose otherwise, Connector/NET is installed in `C:\Program
Files\MySQL\MySQL Connector Net X.X.X', where X.X.X is replaced with
the version of Connector/NET you are installing. New installations do
not overwrite existing versions of Connector/NET.

Depending on your installation type, the installed components will
include some or all of the following components:

   * `bin' - Connector/NET MySQL libraries for different versions of
     the .NET environment.

   * `docs' - contains a CHM of the Connector/NET documentation.

   * `samples' - sample code and applications that use the
     Connector/NET component.

   * `src' - the source code for the Connector/NET component.

You may also use the `/quiet' or `/q' command-line option with the
`msiexec' tool to install the Connector/NET package automatically
(using the default options) with no notification to the user. Using
this method the user cannot select options. Additionally, no prompts,
messages or dialog boxes will be displayed.

     C:\> msiexec /package conector-net.msi /quiet

To provide a progress bar to the user during automatic installation,
use the `/passive' option.


File: manual.info,  Node: connector-net-installation-binary-windows-zip,  Prev: connector-net-installation-binary-windows-installer,  Up: connector-net-installation-windows

20.2.2.3 Installing Connector/NET using the Zip packages
........................................................

If you are having problems running the installer, you can download a
Zip file without an installer as an alternative.  That file is called
`mysql-connector-net-VERSION-noinstall.zip'.  Once downloaded, you can
extract the files to a location of your choice.

The file contains the following directories:

   * `bin' - Connector/NET MySQL libraries for different versions of
     the .NET environment.

   * `Docs' - contains a CHM of the Connector/NET documentation.

   * `Samples' - sample code and applications that use the
     Connector/NET component.

Connector/NET 6.0.x has a different directory structure:

   * `Assemblies' - contains a collection of DLLs that make up the
     connector functionality.

   * `Documentation' - contains the Connector/NET documentation as a
     CHM file.

   * `Samples' - sample code and applications that use the
     Connector/NET component.

There is also another Zip file available for download called
`mysql-connector-net-VERSION-src.zip'.  This file contains the source
code distribution.

The file contains the following directories:

   * `Documentation' - This folder contains the source files to build
     the documentation into the compiled HTML (CHM) format.

   * `Installer' - This folder contains the source files to build the
     Connector/NET installer program.

   * `MySql.Data' - This folder contains the source files for the core
     data provider.

   * `MySql.VisualStudio' - This folder contains the source files for
     the Microsoft Visual Studio extensions.

   * `MySql.Web' - This folder contains the source files for the web
     providers. This includes code for the membership provider, role
     provider and profile provider. These are used in ASP.NET web sites.

   * `Samples' - This folder contains the source files for several
     example applications.

   * `Tests' - Ths folder contains a spreadsheet listing test cases.

   * `VisualStudio' - Contains resources used by the Visual Studio plug
     in.

Finally, you need to ensure that `MySql.Data.dll' is accessible to your
program at build time (and run time). If using Microsoft Visual Studio
you will need to add `MySql.Data' as a Reference to your project.


File: manual.info,  Node: connector-net-installation-unix,  Next: connector-net-installation-source,  Prev: connector-net-installation-windows,  Up: connector-net-installation

20.2.2.4 Installing Connector/NET on Unix with Mono
...................................................

There is no installer available for installing the Connector/NET
component on your Unix installation. Before installing, please ensure
that you have a working Mono project installation. You can test whether
your system has Mono installed by typing:

     shell> mono --version

The version of the Mono JIT compiler will be displayed.

To compile C# source code you will also need to make sure a Mono C#
compiler, is installed. Note that there are two Mono C# compilers
available, `mcs', which accesses the 1.0-profile libraries, and `gmcs',
which acesses the 2.0-profile libraries.

To install Connector/NET on Unix/Mono:

  1. Download the `mysql-connector-net-VERSION-noinstall.zip' and
     extract the contents to a directory of your choice, for example:
     `~/connector-net/'.

  2. In the directory where you unzipped the connector to, change into
     the `bin' directory. Ensure the file `MySql.Data.dll' is present.

  3. You must register the Connector/NET component, `MySql.Data', in
     the Global Assembly Cache (GAC). In the current directory enter the
     `gacutil' command:

          root-shell> gacutil /i MySql.Data.dll

     This will register `MySql.Data' into the GAC. You can check this
     by listing the contents of `/usr/lib/mono/gac', where you will find
     `MySql.Data' if the registration has been successful.

You are now ready to compile your application. You must ensure that
when you compile your application you include the Connector/NET
component using the `-r:' command-line option. For example:

     shell> gmcs -r:System.dll -r:System.Data.dll -r:MySql.Data.dll HelloWorld.cs

Note, the assemblies that need to be referenced will depend on the
requirements of the application, but applications using Connector/NET
will need to provide `-r:MySql.Data' as a minimum.

You can further check your installation by running the compiled
program, for example:

     shell> mono HelloWorld.exe


File: manual.info,  Node: connector-net-installation-source,  Prev: connector-net-installation-unix,  Up: connector-net-installation

20.2.2.5 Installing Connector/NET from the source code
......................................................

*Caution*:

You should read this section only if you are interested in helping us
test our new code. If you just want to get Connector/NET up and running
on your system, you should use a standard release distribution.

*Obtaining the source code*

To be able to access the Connector/NET source tree, you must have
Subversion installed. Subversion is freely available from
`http://subversion.tigris.org/'.

The most recent development source tree is available from our public
Subversion trees at `http://dev.mysql.com/tech-resources/sources.html'.

To checkout out the Connector/NET sources, change to the directory
where you want the copy of the Connector/NET tree to be stored, then
use the following command:

     shell> svn co http://svn.mysql.com/svnpublic/connector-net

Source packages are also available on the downloads page.

*Building the source code on Windows*

The following procedure can be used to build the connector on Microsoft
Windows.

   * Obtain the source code, either from the Subversion server, or
     through one of the prepared source code packages.

   * Navigate to the root of the source code tree.

   * A Microsoft Visual Studio 2005 solution file is available to build
     the connector, this is called `MySQL-VS2005.sln'. Click on this
     file to load the solution into Visual Studio.

   * Select `Build', `Build Solution' from the main menu to build the
     solution.

*Building the source code on Unix*

Support for building Connector/NET on Mono/Unix is currently not
available.


File: manual.info,  Node: connector-net-examples,  Next: connector-net-ref,  Prev: connector-net-installation,  Up: connector-net

20.2.3 Connector/NET Examples and Usage Guide
---------------------------------------------

* Menu:

* connector-net-examples-mysqlcommand::  Using MySqlCommand
* connector-net-examples-mysqlcommandbuilder::  Using MySqlCommandBuilder
* connector-net-examples-mysqlconnection::  Using MySqlConnection
* connector-net-examples-mysqldataadapter::  Using MySqlDataAdapter
* connector-net-examples-mysqldatareader::  Using MySqlDataReader
* connector-net-examples-mysqlexception::  Using MySqlException
* connector-net-examples-mysqlparameter::  Using MySqlParameter
* connector-net-examples-mysqlparametercollection::  Using MySqlParameterCollection
* connector-net-examples-mysqltransaction::  Using MySqlTransaction

Connector/NET comprises several classes that are used to connect to the
database, execute queries and statements, and manage query results.

The following are the major classes of Connector/NET:

   * `MySqlCommand': Represents an SQL statement to execute against a
     MySQL database.

   * `MySqlCommandBuilder': Automatically generates single-table
     commands used to reconcile changes made to a DataSet with the
     associated MySQL database.

   * `MySqlConnection': Represents an open connection to a MySQL Server
     database.

   * `MySqlDataAdapter': Represents a set of data commands and a
     database connection that are used to fill a data set and update a
     MySQL database.

   * `MySqlDataReader': Provides a means of reading a forward-only
     stream of rows from a MySQL database.

   * `MySqlException': The exception that is thrown when MySQL returns
     an error.

   * `MySqlHelper': Helper class that makes it easier to work with the
     provider.

   * `MySqlTransaction': Represents an SQL transaction to be made in a
     MySQL database.

This section contains basic information and examples for each of the
above classes. For a more detailed reference guide please see *Note
connector-net-ref::.


File: manual.info,  Node: connector-net-examples-mysqlcommand,  Next: connector-net-examples-mysqlcommandbuilder,  Prev: connector-net-examples,  Up: connector-net-examples

20.2.3.1 Using MySqlCommand
...........................

* Menu:

* connector-net-examples-mysqlcommand-ctor1::  Class MySqlCommand Constructor Form 1
* connector-net-examples-mysqlcommand-ctor2::  Class MySqlCommand Constructor Form 2
* connector-net-examples-mysqlcommand-ctor3::  Class MySqlCommand Constructor Form 3
* connector-net-examples-mysqlcommand-ctor4::  Class MySqlCommand Constructor Form 4
* connector-net-examples-mysqlcommand-executenonquery::  Method ExecuteNonQuery
* connector-net-examples-mysqlcommand-executereader1::  Method ExecuteReader
* connector-net-examples-mysqlcommand-executereader::  Using ExecuteReader
* connector-net-examples-mysqlcommand-prepare::  Using Prepare
* connector-net-examples-mysqlcommand-executescalar::  Method ExecuteScalar
* connector-net-examples-mysqlcommand-commandtext::  Property CommandText
* connector-net-examples-mysqlcommand-commandtimeout::  Property CommandTimeout
* connector-net-examples-mysqlcommand-commandtype::  Property CommandType
* connector-net-examples-mysqlcommand-connection::  Property Connection
* connector-net-examples-mysqlcommand-isprepared::  Property IsPrepared
* connector-net-examples-mysqlcommand-parameters::  Property Parameters
* connector-net-examples-mysqlcommand-transaction::  Property Transaction
* connector-net-examples-mysqlcommand-updatedrowsource::  Property UpdatedRowSource

Represents an SQL statement to execute against a MySQL database.  This
class cannot be inherited.

`MySqlCommand' features the following methods for executing commands at
a MySQL database:

* Item*                              * Description*
* *Note ExecuteReader:               Executes commands that return rows.
connector-net-examples-mysqlcommand-executereader.
*                                    
* *Note ExecuteNonQuery:             Executes commands such as SQL
connector-net-examples-mysqlcommand-executenonquery.INSERT, DELETE, and UPDATE
*                                    statements.
* *Note ExecuteScalar:               Retrieves a single value (for
connector-net-examples-mysqlcommand-executescalar.example, an aggregate value) from a
*                                    database.

You can reset the `CommandText' property and reuse the `MySqlCommand'
object. However, you must close the *Note MySqlDataReader:
connector-net-examples-mysqldatareader.  before you can execute a new
or previous command.

If a *Note MySqlException: connector-net-examples-mysqlexception.  is
generated by the method executing a `MySqlCommand', the *Note
MySqlConnection: connector-net-examples-mysqlconnection.  remains open.
It is the responsibility of the programmer to close the connection.

*Note*:

Using the '@' symbol for parameters is now the preferred approach
although the old pattern of using '?' is still supported.

Please be aware however that using '@' can cause conflicts when user
variables are also used. To help with this situation please see the
documentation on the `Allow User Variables' connection string option,
which can be found here: *Note
connector-net-examples-mysqlconnection-connectionstring::.  The `Old
Syntax' connection string option has now been deprecated.

*Examples*

The following example creates a *Note MySqlCommand:
connector-net-examples-mysqlcommand.  and a `MySqlConnection'. The
`MySqlConnection' is opened and set as the *Note Connection:
connector-net-examples-mysqlconnection.  for the `MySqlCommand'. The
example then calls *Note ExecuteNonQuery:
connector-net-examples-mysqlcommand-executenonquery, and closes the
connection. To accomplish this, the `ExecuteNonQuery' is passed a
connection string and a query string that is an SQL INSERT statement.

Visual Basic example:

     Public Sub InsertRow(myConnectionString As String)
         " If the connection string is null, use a default.
       If myConnectionString = "" Then
         myConnectionString = "Database=Test;Data Source=localhost;User Id=username;Password=pass"
       End If
       Dim myConnection As New MySqlConnection(myConnectionString)
       Dim myInsertQuery As String = "INSERT INTO Orders (id, customerId, amount) Values(1001, 23, 30.66)"
       Dim myCommand As New MySqlCommand(myInsertQuery)
       myCommand.Connection = myConnection
       myConnection.Open()
       myCommand.ExecuteNonQuery()
       myCommand.Connection.Close()
     End Sub

C# example:

     public void InsertRow(string myConnectionString)
     {
       // If the connection string is null, use a default.
       if(myConnectionString == "")
       {
         myConnectionString = "Database=Test;Data Source=localhost;User Id=username;Password=pass";
       }
       MySqlConnection myConnection = new MySqlConnection(myConnectionString);
       string myInsertQuery = "INSERT INTO Orders (id, customerId, amount) Values(1001, 23, 30.66)";
       MySqlCommand myCommand = new MySqlCommand(myInsertQuery);
       myCommand.Connection = myConnection;
       myConnection.Open();
       myCommand.ExecuteNonQuery();
       myCommand.Connection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-ctor1,  Next: connector-net-examples-mysqlcommand-ctor2,  Prev: connector-net-examples-mysqlcommand,  Up: connector-net-examples-mysqlcommand

20.2.3.2 Class MySqlCommand Constructor Form 1
..............................................

*Overload methods for MySqlCommand*

Initializes a new instance of the MySqlCommand class.

*Examples*

The following example creates a MySqlCommand and sets some of its
properties.

*Note*:

This example shows how to use one of the overloaded versions of the
`MySqlCommand' constructor. For other examples that might be available,
see the individual overload topics.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim myConnection As New MySqlConnection _
         ("Persist Security Info=False;database=test;server=myServer")
       myConnection.Open()
       Dim myTrans As MySqlTransaction = myConnection.BeginTransaction()
       Dim mySelectQuery As String = "SELECT * FROM MyTable"
       Dim myCommand As New MySqlCommand(mySelectQuery, myConnection, myTrans)
       myCommand.CommandTimeout = 20
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       MySqlConnection myConnection = new MySqlConnection("Persist Security Info=False;
         database=test;server=myServer");
       myConnection.Open();
       MySqlTransaction myTrans = myConnection.BeginTransaction();
       string mySelectQuery = "SELECT * FROM myTable";
       MySqlCommand myCommand = new MySqlCommand(mySelectQuery, myConnection,myTrans);
       myCommand.CommandTimeout = 20;
     }

C++ example:

     public:
     void CreateMySqlCommand()
     {
       MySqlConnection* myConnection = new MySqlConnection(S"Persist Security Info=False;
         database=test;server=myServer");
       myConnection->Open();
       MySqlTransaction* myTrans = myConnection->BeginTransaction();
       String* mySelectQuery = S"SELECT * FROM myTable";
       MySqlCommand* myCommand = new MySqlCommand(mySelectQuery, myConnection, myTrans);
       myCommand->CommandTimeout = 20;
     };

Initializes a new instance of the MySqlCommand class.

The base constructor initializes all fields to their default values.
The following table shows initial property values for an instance of
`MySqlCommand'.

* Properties*                        * Initial Value*
* `CommandText' *                    * empty string ("")*
* `CommandTimeout' *                 * 30*
* `CommandType' *                    * CommandType.Text*
* `Connection' *                     * Null*

You can change the value for any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim myCommand As New MySqlCommand()
       myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       MySqlCommand myCommand = new MySqlCommand();
       myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-ctor2,  Next: connector-net-examples-mysqlcommand-ctor3,  Prev: connector-net-examples-mysqlcommand-ctor1,  Up: connector-net-examples-mysqlcommand

20.2.3.3 Class MySqlCommand Constructor Form 2
..............................................

Initializes a new instance of the `MySqlCommand' class with the text of
the query.

*Parameters:* The text of the query.

When an instance of `MySqlCommand' is created, the following read/write
properties are set to initial values.

* Properties*                        * Initial Value*
* `CommandText' *                    * `cmdText' *
* `CommandTimeout' *                 * 30*
* `CommandType' *                    * CommandType.Text*
* `Connection' *                     * Null*

You can change the value for any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim sql as String = "SELECT * FROM mytable"
       Dim myCommand As New MySqlCommand(sql)
       myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       string sql = "SELECT * FROM mytable";
       MySqlCommand myCommand = new MySqlCommand(sql);
       myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-ctor3,  Next: connector-net-examples-mysqlcommand-ctor4,  Prev: connector-net-examples-mysqlcommand-ctor2,  Up: connector-net-examples-mysqlcommand

20.2.3.4 Class MySqlCommand Constructor Form 3
..............................................

Initializes a new instance of the `MySqlCommand' class with the text of
the query and a `MySqlConnection'.

*Parameters:* The text of the query.

*Parameters:* A `MySqlConnection' that represents the connection to an
instance of SQL Server.

When an instance of `MySqlCommand' is created, the following read/write
properties are set to initial values.

* Properties*                        * Initial Value*
* `CommandText' *                    * `cmdText' *
* `CommandTimeout' *                 * 30*
* `CommandType' *                    * CommandType.Text*
* `Connection' *                     * `connection' *

You can change the value for any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim conn as new MySqlConnection("server=myServer")
       Dim sql as String = "SELECT * FROM mytable"
       Dim myCommand As New MySqlCommand(sql, conn)
       myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       MySqlConnection conn = new MySqlConnection("server=myserver");
       string sql = "SELECT * FROM mytable";
       MySqlCommand myCommand = new MySqlCommand(sql, conn);
       myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-ctor4,  Next: connector-net-examples-mysqlcommand-executenonquery,  Prev: connector-net-examples-mysqlcommand-ctor3,  Up: connector-net-examples-mysqlcommand

20.2.3.5 Class MySqlCommand Constructor Form 4
..............................................

Initializes a new instance of the `MySqlCommand' class with the text of
the query, a `MySqlConnection', and the `MySqlTransaction'.

*Parameters:* The text of the query.

*Parameters:* A `MySqlConnection' that represents the connection to an
instance of SQL Server.

*Parameters:* The `MySqlTransaction' in which the `MySqlCommand'
executes.

When an instance of `MySqlCommand' is created, the following read/write
properties are set to initial values.

* Properties*                        * Initial Value*
* `CommandText' *                    * `cmdText' *
* `CommandTimeout' *                 * 30*
* `CommandType' *                    * CommandType.Text*
* `Connection' *                     * `connection' *

You can change the value for any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim conn as new MySqlConnection("server=myServer")
       conn.Open();
       Dim txn as MySqlTransaction = conn.BeginTransaction()
       Dim sql as String = "SELECT * FROM mytable"
       Dim myCommand As New MySqlCommand(sql, conn, txn)
       myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       MySqlConnection conn = new MySqlConnection("server=myserver")
       conn.Open();
       MySqlTransaction txn = conn.BeginTransaction();
       string sql = "SELECT * FROM mytable";
       MySqlCommand myCommand = new MySqlCommand(sql, conn, txn);
       myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-executenonquery,  Next: connector-net-examples-mysqlcommand-executereader1,  Prev: connector-net-examples-mysqlcommand-ctor4,  Up: connector-net-examples-mysqlcommand

20.2.3.6 Method ExecuteNonQuery
...............................

Executes an SQL statement against the connection and returns the number
of rows affected.

*Returns:* Number of rows affected

You can use ExecuteNonQuery to perform any type of database operation,
however any resultsets returned will not be available. Any output
parameters used in calling a stored procedure will be populated with
data and can be retrieved after execution is complete. For UPDATE,
INSERT, and DELETE statements, the return value is the number of rows
affected by the command. For all other types of statements, the return
value is -1.

*Examples*

The following example creates a MySqlCommand and then executes it using
ExecuteNonQuery. The example is passed a string that is an SQL
statement (such as UPDATE, INSERT, or DELETE) and a string to use to
connect to the data source.

Visual Basic example:

     Public Sub CreateMySqlCommand(myExecuteQuery As String, myConnection As MySqlConnection)
       Dim myCommand As New MySqlCommand(myExecuteQuery, myConnection)
       myCommand.Connection.Open()
       myCommand.ExecuteNonQuery()
       myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlCommand(string myExecuteQuery, MySqlConnection myConnection)
     {
       MySqlCommand myCommand = new MySqlCommand(myExecuteQuery, myConnection);
       myCommand.Connection.Open();
       myCommand.ExecuteNonQuery();
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-executereader1,  Next: connector-net-examples-mysqlcommand-executereader,  Prev: connector-net-examples-mysqlcommand-executenonquery,  Up: connector-net-examples-mysqlcommand

20.2.3.7 Method ExecuteReader
.............................

Sends the `CommandText' to the `MySqlConnection'Connection, and builds a
`MySqlDataReader' using one of the `CommandBehavior' values.

*Parameters:* One of the `CommandBehavior' values.

When the `CommandType' property is set to `StoredProcedure', the
`CommandText' property should be set to the name of the stored
procedure. The command executes this stored procedure when you call
`ExecuteReader'.

The `MySqlDataReader' supports a special mode that enables large binary
values to be read efficiently. For more information, see the
`SequentialAccess' setting for `CommandBehavior'.

While the `MySqlDataReader' is in use, the associated `MySqlConnection'
is busy serving the `MySqlDataReader'. While in this state, no other
operations can be performed on the `MySqlConnection' other than closing
it. This is the case until the `MySqlDataReader.Close' method of the
`MySqlDataReader' is called. If the `MySqlDataReader' is created with
`CommandBehavior' set to `CloseConnection', closing the
`MySqlDataReader' closes the connection automatically.

*Note*:

When calling `ExecuteReader' with the `SingleRow' behavior, you should
be aware that using a `limit' clause in your SQL will cause all rows
(up to the limit given) to be retrieved by the client. The
`MySqlDataReader.Read' method will still return false after the first
row but pulling all rows of data into the client will have a
performance impact. If the `limit' clause is not necessary, it should
be avoided.

*Returns:* A `MySqlDataReader' object.


File: manual.info,  Node: connector-net-examples-mysqlcommand-executereader,  Next: connector-net-examples-mysqlcommand-prepare,  Prev: connector-net-examples-mysqlcommand-executereader1,  Up: connector-net-examples-mysqlcommand

20.2.3.8 Using ExecuteReader
............................

Sends the `CommandText' to the `MySqlConnection'Connection and builds a
`MySqlDataReader'.

*Returns:* A `MySqlDataReader' object.

When the `CommandType' property is set to `StoredProcedure', the
`CommandText' property should be set to the name of the stored
procedure. The command executes this stored procedure when you call
`ExecuteReader'.

While the `MySqlDataReader' is in use, the associated `MySqlConnection'
is busy serving the `MySqlDataReader'. While in this state, no other
operations can be performed on the `MySqlConnection' other than closing
it. This is the case until the `MySqlDataReader.Close' method of the
`MySqlDataReader' is called.

*Examples*

The following example creates a `MySqlCommand', then executes it by
passing a string that is an SQL *Note `SELECT': select.  statement, and
a string to use to connect to the data source.

Visual Basic example:

     Public Sub CreateMySqlDataReader(mySelectQuery As String, myConnection As MySqlConnection)
       Dim myCommand As New MySqlCommand(mySelectQuery, myConnection)
       myConnection.Open()
       Dim myReader As MySqlDataReader
       myReader = myCommand.ExecuteReader()
       Try
         While myReader.Read()
             Console.WriteLine(myReader.GetString(0))
         End While
       Finally
         myReader.Close
         myConnection.Close
       End Try
     End Sub

C# example:

     public void CreateMySqlDataReader(string mySelectQuery, MySqlConnection myConnection)
     {
       MySqlCommand myCommand = new MySqlCommand(mySelectQuery, myConnection);
       myConnection.Open();
       MySqlDataReader myReader;
       myReader = myCommand.ExecuteReader();
       try
       {
         while(myReader.Read())
         {
           Console.WriteLine(myReader.GetString(0));
         }
       }
       finally
       {
         myReader.Close();
         myConnection.Close();
       }
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-prepare,  Next: connector-net-examples-mysqlcommand-executescalar,  Prev: connector-net-examples-mysqlcommand-executereader,  Up: connector-net-examples-mysqlcommand

20.2.3.9 Using Prepare
......................

Creates a prepared version of the command on an instance of MySQL
Server.

Prepared statements are only supported on MySQL version 4.1 and higher.
Calling prepare while connected to earlier versions of MySQL will
succeed but will execute the statement in the same way as unprepared.

*Examples*

The following example demonstrates the use of the `Prepare' method.

Visual Basic example:

     public sub PrepareExample()
       Dim cmd as New MySqlCommand("INSERT INTO mytable VALUES (?val)", myConnection)
       cmd.Parameters.Add( "?val", 10 )
       cmd.Prepare()
       cmd.ExecuteNonQuery()

       cmd.Parameters(0).Value = 20
       cmd.ExecuteNonQuery()
     end sub

C# example:

     private void PrepareExample()
     {
       MySqlCommand cmd = new MySqlCommand("INSERT INTO mytable VALUES (@val)", myConnection);
       cmd.Parameters.Add( "@val", 10 );
       cmd.Prepare();
       cmd.ExecuteNonQuery();

       cmd.Parameters[0].Value = 20;
       cmd.ExecuteNonQuery();
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-executescalar,  Next: connector-net-examples-mysqlcommand-commandtext,  Prev: connector-net-examples-mysqlcommand-prepare,  Up: connector-net-examples-mysqlcommand

20.2.3.10 Method ExecuteScalar
..............................

Executes the query, and returns the first column of the first row in
the result set returned by the query. Extra columns or rows are ignored.

*Returns:* The first column of the first row in the result set, or a
null reference if the result set is empty

Use the `ExecuteScalar' method to retrieve a single value (for example,
an aggregate value) from a database. This requires less code than using
the `ExecuteReader' method, and then performing the operations
necessary to generate the single value using the data returned by a
`MySqlDataReader'

A typical `ExecuteScalar' query can be formatted as in the following C#
example:

C# example:

     cmd.CommandText = "select count(*) from region";
     Int32 count = (int32) cmd.ExecuteScalar();

*Examples*

The following example creates a `MySqlCommand' and then executes it
using `ExecuteScalar'. The example is passed a string that is an SQL
statement that returns an aggregate result, and a string to use to
connect to the data source.

Visual Basic example:

     Public Sub CreateMySqlCommand(myScalarQuery As String, myConnection As MySqlConnection)
       Dim myCommand As New MySqlCommand(myScalarQuery, myConnection)
       myCommand.Connection.Open()
       myCommand.ExecuteScalar()
       myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlCommand(string myScalarQuery, MySqlConnection myConnection)
     {
       MySqlCommand myCommand = new MySqlCommand(myScalarQuery, myConnection);
       myCommand.Connection.Open();
       myCommand.ExecuteScalar();
       myConnection.Close();
     }

C++ example:

     public:
       void CreateMySqlCommand(String* myScalarQuery, MySqlConnection* myConnection)
       {
         MySqlCommand* myCommand = new MySqlCommand(myScalarQuery, myConnection);
         myCommand->Connection->Open();
         myCommand->ExecuteScalar();
         myConnection->Close();
       }


File: manual.info,  Node: connector-net-examples-mysqlcommand-commandtext,  Next: connector-net-examples-mysqlcommand-commandtimeout,  Prev: connector-net-examples-mysqlcommand-executescalar,  Up: connector-net-examples-mysqlcommand

20.2.3.11 Property CommandText
..............................

Gets or sets the SQL statement to execute at the data source.

*Value:* The SQL statement or stored procedure to execute. The default
is an empty string.

When the `CommandType' property is set to `StoredProcedure', the
`CommandText' property should be set to the name of the stored
procedure. The user may be required to use escape character syntax if
the stored procedure name contains any special characters. The command
executes this stored procedure when you call one of the Execute methods.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim myCommand As New MySqlCommand()
       myCommand.CommandText = "SELECT * FROM Mytable ORDER BY id"
       myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       MySqlCommand myCommand = new MySqlCommand();
       myCommand.CommandText = "SELECT * FROM mytable ORDER BY id";
       myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-commandtimeout,  Next: connector-net-examples-mysqlcommand-commandtype,  Prev: connector-net-examples-mysqlcommand-commandtext,  Up: connector-net-examples-mysqlcommand

20.2.3.12 Property CommandTimeout
.................................

Gets or sets the wait time before terminating the attempt to execute a
command and generating an error.

*Value:* The time (in seconds) to wait for the command to execute. The
default is 30 seconds.

MySQL currently does not support any method of canceling a pending or
executing operation. All commands issued against a MySQL server will
execute until completion or until an exception occurs.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about
CommandTimeout in the Knowledge Base article, Why CommandTimeout is not
Supported (https://kb.mysql.com/view.php?id=4920). Access to the MySQL
Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: connector-net-examples-mysqlcommand-commandtype,  Next: connector-net-examples-mysqlcommand-connection,  Prev: connector-net-examples-mysqlcommand-commandtimeout,  Up: connector-net-examples-mysqlcommand

20.2.3.13 Property CommandType
..............................

Gets or sets a value indicating how the `CommandText' property is to be
interpreted.

*Value:* One of the `System.Data.CommandType' values. The default is
`Text'.

When you set the `CommandType' property to `StoredProcedure', you
should set the `CommandText' property to the name of the stored
procedure. The command executes this stored procedure when you call one
of the Execute methods.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim myCommand As New MySqlCommand()
       myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       MySqlCommand myCommand = new MySqlCommand();
       myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-connection,  Next: connector-net-examples-mysqlcommand-isprepared,  Prev: connector-net-examples-mysqlcommand-commandtype,  Up: connector-net-examples-mysqlcommand

20.2.3.14 Property Connection
.............................

Gets or sets the `MySqlConnection' used by this instance of the
`MySqlCommand'.

*Value:* The connection to a data source. The default value is a null
reference (`Nothing' in Visual Basic).

If you set `Connection' while a transaction is in progress and the
`Transaction' property is not null, an `InvalidOperationException' is
generated. If the `Transaction' property is not null and the
transaction has already been committed or rolled back, `Transaction' is
set to null.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim mySelectQuery As String = "SELECT * FROM mytable ORDER BY id"
       Dim myConnectString As String = "Persist Security Info=False;database=test;server=myServer"
       Dim myCommand As New MySqlCommand(mySelectQuery)
       myCommand.Connection = New MySqlConnection(myConnectString)
       myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       string mySelectQuery = "SELECT * FROM mytable ORDER BY id";
       string myConnectString = "Persist Security Info=False;database=test;server=myServer";
       MySqlCommand myCommand = new MySqlCommand(mySelectQuery);
       myCommand.Connection = new MySqlConnection(myConnectString);
       myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-isprepared,  Next: connector-net-examples-mysqlcommand-parameters,  Prev: connector-net-examples-mysqlcommand-connection,  Up: connector-net-examples-mysqlcommand

20.2.3.15 Property IsPrepared
.............................

Returns true if the statement is prepared.


File: manual.info,  Node: connector-net-examples-mysqlcommand-parameters,  Next: connector-net-examples-mysqlcommand-transaction,  Prev: connector-net-examples-mysqlcommand-isprepared,  Up: connector-net-examples-mysqlcommand

20.2.3.16 Property Parameters
.............................

Get the `MySqlParameterCollection'

*Value:* The parameters of the SQL statement or stored procedure. The
default is an empty collection.

Connector/Net does not support unnamed parameters. Every parameter
added to the collection must have an associated name.

*Examples*

The following example creates a `MySqlCommand' and displays its
parameters.  To accomplish this, the method is passed a
`MySqlConnection', a query string that is a SQL *Note `SELECT': select.
statement, and an array of `MySqlParameter' objects.

Visual Basic example:

     Public Sub CreateMySqlCommand(myConnection As MySqlConnection, _
         mySelectQuery As String, myParamArray() As MySqlParameter)
       Dim myCommand As New MySqlCommand(mySelectQuery, myConnection)
       myCommand.CommandText = "SELECT id, name FROM mytable WHERE age=@age"
       myCommand.UpdatedRowSource = UpdateRowSource.Both
       myCommand.Parameters.Add(myParamArray)
       Dim j As Integer
       For j = 0 To myCommand.Parameters.Count - 1
         myCommand.Parameters.Add(myParamArray(j))
       Next j
       Dim myMessage As String = ""
       Dim i As Integer
       For i = 0 To myCommand.Parameters.Count - 1
         myMessage += myCommand.Parameters(i).ToString() & ControlChars.Cr
       Next i
       Console.WriteLine(myMessage)
     End Sub

C# example:

     public void CreateMySqlCommand(MySqlConnection myConnection,
       string mySelectQuery,
       MySqlParameter[] myParamArray)
     {
       MySqlCommand myCommand = new MySqlCommand(mySelectQuery, myConnection);
       myCommand.CommandText = "SELECT id, name FROM mytable WHERE age=@age";
       myCommand.Parameters.Add(myParamArray);
       for (int j=0; j<myParamArray.Length; j++)
       {
         myCommand.Parameters.Add(myParamArray[j]) ;
       }
       string myMessage = "";
       for (int i = 0; i < myCommand.Parameters.Count; i++)
       {
         myMessage += myCommand.Parameters[i].ToString() + "\n";
       }
       MessageBox.Show(myMessage);
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-transaction,  Next: connector-net-examples-mysqlcommand-updatedrowsource,  Prev: connector-net-examples-mysqlcommand-parameters,  Up: connector-net-examples-mysqlcommand

20.2.3.17 Property Transaction
..............................

Gets or sets the `MySqlTransaction' within which the `MySqlCommand'
executes.

*Value:* The `MySqlTransaction'. The default value is a null reference
(`Nothing' in Visual Basic).

You cannot set the `Transaction' property if it is already set to a
specific value, and the command is in the process of executing. If you
set the transaction property to a `MySqlTransaction' object that is not
connected to the same `MySqlConnection' as the `MySqlCommand' object,
an exception will be thrown the next time you attempt to execute a
statement.


File: manual.info,  Node: connector-net-examples-mysqlcommand-updatedrowsource,  Prev: connector-net-examples-mysqlcommand-transaction,  Up: connector-net-examples-mysqlcommand

20.2.3.18 Property UpdatedRowSource
...................................

Gets or sets how command results are applied to the `DataRow' when used
by the `System.Data.Common.DbDataAdapter.Update' method of the
`System.Data.Common.DbDataAdapter'.

*Value:* One of the `UpdateRowSource' values.

The default `System.Data.UpdateRowSource' value is `Both' unless the
command is automatically generated (as in the case of the
`MySqlCommandBuilder'), in which case the default is `None'.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder,  Next: connector-net-examples-mysqlconnection,  Prev: connector-net-examples-mysqlcommand,  Up: connector-net-examples

20.2.3.19 Using MySqlCommandBuilder
...................................

* Menu:

* connector-net-examples-mysqlcommandbuilder-ctor::  Class MySqlCommandBuilder Constructor
* connector-net-examples-mysqlcommandbuilder-ctor1::  Class MySqlCommandBuilder Constructor Form 1
* connector-net-examples-mysqlcommandbuilder-ctor2::  Class MySqlCommandBuilder Constructor Form 2
* connector-net-examples-mysqlcommandbuilder-ctor3::  Class MySqlCommandBuilder Constructor Form 3
* connector-net-examples-mysqlcommandbuilder-dataadapter::  Property DataAdapter
* connector-net-examples-mysqlcommandbuilder-quoteprefix::  Property QuotePrefix
* connector-net-examples-mysqlcommandbuilder-quotesuffix::  Property QuoteSuffix
* connector-net-examples-mysqlcommandbuilder-getdeletecommand::  Method GetDeleteCommand
* connector-net-examples-mysqlcommandbuilder-getinsertcommand::  Method GetInsertCommand
* connector-net-examples-mysqlcommandbuilder-getupdatecommand::  Method GetUpdateCommand
* connector-net-examples-mysqlcommandbuilder-refreshschema::  Method RefreshSchema

Automatically generates single-table commands used to reconcile changes
made to a DataSet with the associated MySQL database.  This class
cannot be inherited.

The `MySqlDataAdapter' does not automatically generate the SQL
statements required to reconcile changes made to a
`System.Data.DataSet'DataSet with the associated instance of MySQL.
However, you can create a `MySqlCommandBuilder' object to automatically
generate SQL statements for single-table updates if you set the
`MySqlDataAdapter.SelectCommand'SelectCommand property of the
`MySqlDataAdapter'. Then, any additional SQL statements that you do not
set are generated by the `MySqlCommandBuilder'.

The `MySqlCommandBuilder' registers itself as a listener for
`MySqlDataAdapter.OnRowUpdating'RowUpdating events whenever you set the
`DataAdapter' property. You can only associate one `MySqlDataAdapter' or
`MySqlCommandBuilder' object with each other at one time.

To generate INSERT, UPDATE, or DELETE statements, the
`MySqlCommandBuilder' uses the `SelectCommand' property to retrieve a
required set of metadata automatically. If you change the
`SelectCommand' after the metadata has is retrieved (for example, after
the first update), you should call the `RefreshSchema' method to update
the metadata.

The `SelectCommand' must also return at least one primary key or unique
column. If none are present, an `InvalidOperation' exception is
generated, and the commands are not generated.

When using `MySqlCommandbuilder' and *Note `INSERT': insert. you should
set the `ReturnGeneratedIdentifiers' property to `true' to ensure that
`AUTO_INCREMENT' fields in MySQL tables return the automatically
generated value.

The `MySqlCommandBuilder' also uses the
`MySqlCommand.Connection'Connection,
`MySqlCommand.CommandTimeout'CommandTimeout, and
`MySqlCommand.Transaction'Transaction properties referenced by the
`SelectCommand'.  The user should call `RefreshSchema' if any of these
properties are modified, or if the `SelectCommand' itself is replaced.
Otherwise the `MySqlDataAdapter.InsertCommand'InsertCommand,
`MySqlDataAdapter.UpdateCommand'UpdateCommand, and
`MySqlDataAdapter.DeleteCommand'DeleteCommand properties retain their
previous values.

If you call `Dispose', the `MySqlCommandBuilder' is disassociated from
the `MySqlDataAdapter', and the generated commands are no longer used.

*Note*:

Caution must be used when using `MySqlCommandBuilder' on MySql 4.0
systems.  With MySQL 4.0, database/schema information is not provided to
the connector for a query. This means that a query that pulls columns
from two identically named tables in two or more different databases
will not cause an exception to be thrown but will not work correctly.
Even more dangerous is the situation where your select statement
references database X but is executed in database Y and both databases
have tables with similar layouts. This situation can cause unwanted
changes or deletes. This note does not apply to MySQL versions 4.1 and
later.

*Examples*

The following example uses the `MySqlCommand', along `MySqlDataAdapter'
and `MySqlConnection', to select rows from a data source. The example
is passed an initialized `System.Data.DataSet', a connection string, a
query string that is an SQL *Note `SELECT': select. statement, and a
string that is the name of the database table. The example then creates
a `MySqlCommandBuilder'.

Visual Basic example:

     Public Shared Function SelectRows(myConnection As String, mySelectQuery As String, myTableName As String) As DataSet
       Dim myConn As New MySqlConnection(myConnection)
       Dim myDataAdapter As New MySqlDataAdapter()
       myDataAdapter.SelectCommand = New MySqlCommand(mySelectQuery, myConn)
       Dim cb As SqlCommandBuilder = New MySqlCommandBuilder(myDataAdapter)
       myConn.Open()
       Dim ds As DataSet = New DataSet
       myDataAdapter.Fill(ds, myTableName)
       ' Code to modify data in DataSet here
       ' Without the MySqlCommandBuilder this line would fail.
       myDataAdapter.Update(ds, myTableName)
       myConn.Close()
     End Function 'SelectRows

C# example:

     public static DataSet SelectRows(string myConnection, string mySelectQuery, string myTableName)
     {
       MySqlConnection myConn = new MySqlConnection(myConnection);
       MySqlDataAdapter myDataAdapter = new MySqlDataAdapter();
       myDataAdapter.SelectCommand = new MySqlCommand(mySelectQuery, myConn);
       MySqlCommandBuilder cb = new MySqlCommandBuilder(myDataAdapter);
       myConn.Open();
       DataSet ds = new DataSet();
       myDataAdapter.Fill(ds, myTableName);
       //code to modify data in DataSet here
       //Without the MySqlCommandBuilder this line would fail
       myDataAdapter.Update(ds, myTableName);
       myConn.Close();
       return ds;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-ctor,  Next: connector-net-examples-mysqlcommandbuilder-ctor1,  Prev: connector-net-examples-mysqlcommandbuilder,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.20 Class MySqlCommandBuilder Constructor
...............................................

Initializes a new instance of the `MySqlCommandBuilder' class.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-ctor1,  Next: connector-net-examples-mysqlcommandbuilder-ctor2,  Prev: connector-net-examples-mysqlcommandbuilder-ctor,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.21 Class MySqlCommandBuilder Constructor Form 1
......................................................

Initializes a new instance of the `MySqlCommandBuilder' class and sets
the last one wins property.

*Parameters:* False to generate change protection code. True otherwise.

The `lastOneWins' parameter indicates whether SQL code should be
included with the generated DELETE and UPDATE commands that checks the
underlying data for changes.  If `lastOneWins' is true then this code is
not included and data records could be overwritten in a multi-user or
multi-threaded environments. Setting `lastOneWins' to false will
include this check which will cause a concurrency exception to be
thrown if the underlying data record has changed without our knowledge.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-ctor2,  Next: connector-net-examples-mysqlcommandbuilder-ctor3,  Prev: connector-net-examples-mysqlcommandbuilder-ctor1,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.22 Class MySqlCommandBuilder Constructor Form 2
......................................................

Initializes a new instance of the `MySqlCommandBuilder' class with the
associated `MySqlDataAdapter' object.

*Parameters:* The `MySqlDataAdapter' to use.

The `MySqlCommandBuilder' registers itself as a listener for
`MySqlDataAdapter.RowUpdating' events that are generated by the
`MySqlDataAdapter' specified in this property.

When you create a new instance `MySqlCommandBuilder', any existing
`MySqlCommandBuilder' associated with this `MySqlDataAdapter' is
released.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-ctor3,  Next: connector-net-examples-mysqlcommandbuilder-dataadapter,  Prev: connector-net-examples-mysqlcommandbuilder-ctor2,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.23 Class MySqlCommandBuilder Constructor Form 3
......................................................

Initializes a new instance of the `MySqlCommandBuilder' class with the
associated `MySqlDataAdapter' object.

*Parameters:* The `MySqlDataAdapter' to use.

*Parameters:* False to generate change protection code. True otherwise.

The `MySqlCommandBuilder' registers itself as a listener for
`MySqlDataAdapter.RowUpdating' events that are generated by the
`MySqlDataAdapter' specified in this property.

When you create a new instance `MySqlCommandBuilder', any existing
`MySqlCommandBuilder' associated with this `MySqlDataAdapter' is
released.

The `lastOneWins' parameter indicates whether SQL code should be
included with the generated DELETE and UPDATE commands that checks the
underlying data for changes.  If `lastOneWins' is true then this code is
not included and data records could be overwritten in a multi-user or
multi-threaded environments. Setting `lastOneWins' to false will
include this check which will cause a concurrency exception to be
thrown if the underlying data record has changed without our knowledge.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-dataadapter,  Next: connector-net-examples-mysqlcommandbuilder-quoteprefix,  Prev: connector-net-examples-mysqlcommandbuilder-ctor3,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.24 Property DataAdapter
..............................

Gets or sets a `MySqlDataAdapter' object for which SQL statements are
automatically generated.

*Value:* A `MySqlDataAdapter' object.

The `MySqlCommandBuilder' registers itself as a listener for
`MySqlDataAdapter.RowUpdating' events that are generated by the
`MySqlDataAdapter' specified in this property.

When you create a new instance `MySqlCommandBuilder', any existing
`MySqlCommandBuilder' associated with this `MySqlDataAdapter' is
released.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-quoteprefix,  Next: connector-net-examples-mysqlcommandbuilder-quotesuffix,  Prev: connector-net-examples-mysqlcommandbuilder-dataadapter,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.25 Property QuotePrefix
..............................

Gets or sets the beginning character or characters to use when
specifying MySQL database objects (for example, tables or columns)
whose names contain characters such as spaces or reserved tokens.

*Value:* The beginning character or characters to use. The default
value is `.

Database objects in MySQL can contain special characters such as spaces
that would make normal SQL strings impossible to correctly parse. Use
of the `QuotePrefix' and the `QuoteSuffix' properties allows the
`MySqlCommandBuilder' to build SQL statements that handle this
situation.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-quotesuffix,  Next: connector-net-examples-mysqlcommandbuilder-getdeletecommand,  Prev: connector-net-examples-mysqlcommandbuilder-quoteprefix,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.26 Property QuoteSuffix
..............................

Gets or sets the beginning character or characters to use when
specifying MySQL database objects (for example, tables or columns)
whose names contain characters such as spaces or reserved tokens.

*Value:* The beginning character or characters to use. The default
value is `.

Database objects in MySQL can contain special characters such as spaces
that would make normal SQL strings impossible to correctly parse. Use
of the `QuotePrefix' and the `QuoteSuffix' properties allows the
`MySqlCommandBuilder' to build SQL statements that handle this
situation.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-getdeletecommand,  Next: connector-net-examples-mysqlcommandbuilder-getinsertcommand,  Prev: connector-net-examples-mysqlcommandbuilder-quotesuffix,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.27 Method GetDeleteCommand
.................................

Gets the automatically generated `MySqlCommand' object required to
perform deletions on the database.

*Returns:* The `MySqlCommand' object generated to handle delete
operations.

An application can use the `GetDeleteCommand' method for informational
or troubleshooting purposes because it returns the `MySqlCommand'
object to be executed.

You can also use `GetDeleteCommand' as the basis of a modified command.
For example, you might call `GetDeleteCommand' and modify the
`MySqlCommand.CommandTimeout' value, and then explicitly set that on the
`MySqlDataAdapter'.

After the SQL statement is first generated, the application must
explicitly call `RefreshSchema' if it changes the statement in any way.
Otherwise, the `GetDeleteCommand' will be still be using information
from the previous statement, which might not be correct. The SQL
statements are first generated either when the application calls
`System.Data.Common.DataAdapter.Update' or `GetDeleteCommand'.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-getinsertcommand,  Next: connector-net-examples-mysqlcommandbuilder-getupdatecommand,  Prev: connector-net-examples-mysqlcommandbuilder-getdeletecommand,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.28 Method GetInsertCommand
.................................

Gets the automatically generated `MySqlCommand' object required to
perform insertions on the database.

*Returns:* The `MySqlCommand' object generated to handle insert
operations.

An application can use the `GetInsertCommand' method for informational
or troubleshooting purposes because it returns the `MySqlCommand'
object to be executed.

You can also use the `GetInsertCommand' as the basis of a modified
command. For example, you might call `GetInsertCommand' and modify the
`MySqlCommand.CommandTimeout' value, and then explicitly set that on the
`MySqlDataAdapter'.

After the SQL statement is first generated, the application must
explicitly call `RefreshSchema' if it changes the statement in any way.
Otherwise, the `GetInsertCommand' will be still be using information
from the previous statement, which might not be correct. The SQL
statements are first generated either when the application calls
`System.Data.Common.DataAdapter.Update' or `GetInsertCommand'.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-getupdatecommand,  Next: connector-net-examples-mysqlcommandbuilder-refreshschema,  Prev: connector-net-examples-mysqlcommandbuilder-getinsertcommand,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.29 Method GetUpdateCommand
.................................

Gets the automatically generated `MySqlCommand' object required to
perform updates on the database.

*Returns:* The `MySqlCommand' object generated to handle update
operations.

An application can use the `GetUpdateCommand' method for informational
or troubleshooting purposes because it returns the `MySqlCommand'
object to be executed.

You can also use `GetUpdateCommand' as the basis of a modified command.
For example, you might call `GetUpdateCommand' and modify the
`MySqlCommand.CommandTimeout' value, and then explicitly set that on the
`MySqlDataAdapter'.

After the SQL statement is first generated, the application must
explicitly call `RefreshSchema' if it changes the statement in any way.
Otherwise, the `GetUpdateCommand' will be still be using information
from the previous statement, which might not be correct. The SQL
statements are first generated either when the application calls
`System.Data.Common.DataAdapter.Update' or `GetUpdateCommand'.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-refreshschema,  Prev: connector-net-examples-mysqlcommandbuilder-getupdatecommand,  Up: connector-net-examples-mysqlcommandbuilder

20.2.3.30 Method RefreshSchema
..............................

Refreshes the database schema information used to generate INSERT,
UPDATE, or DELETE statements.

An application should call `RefreshSchema' whenever the *Note `SELECT':
select. statement associated with the `MySqlCommandBuilder' changes.

An application should call `RefreshSchema' whenever the
`MySqlDataAdapter.SelectCommand' value of the `MySqlDataAdapter'
changes.

MySQL Enterprise

MySQL Enterprise subscribers will find more information on this topic
in the Knowledge Base article, Understanding MySqlCommandBuilder and
the LastOneWins Setting (https://kb.mysql.com/view.php?id=4922). For
information about subscribing to MySQL Enterprise see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: connector-net-examples-mysqlconnection,  Next: connector-net-examples-mysqldataadapter,  Prev: connector-net-examples-mysqlcommandbuilder,  Up: connector-net-examples

20.2.3.31 Using MySqlConnection
...............................

* Menu:

* connector-net-examples-mysqlconnection-defctor::  Class MySqlConnection Constructor (Default)
* connector-net-examples-mysqlconnection-ctor1::  Class MySqlConnection Constructor Form 1
* connector-net-examples-mysqlconnection-connectionstring::  Property ConnectionString
* connector-net-examples-mysqlconnection-open::  Method Open
* connector-net-examples-mysqlconnection-database::  Property Database
* connector-net-examples-mysqlconnection-state::  Property State
* connector-net-examples-mysqlconnection-serverversion::  Property ServerVersion
* connector-net-examples-mysqlconnection-close::  Method Close
* connector-net-examples-mysqlconnection-createcommand::  Method CreateCommand
* connector-net-examples-mysqlconnection-begintransaction::  Method BeginTransaction
* connector-net-examples-mysqlconnection-begintransaction1::  Method BeginTransaction (overload)
* connector-net-examples-mysqlconnection-changedatabase::  Method ChangeDatabase
* connector-net-examples-mysqlconnection-statechange::  Event Handler StateChange
* connector-net-examples-mysqlconnection-infomessage::  Event Handler InfoMessage
* connector-net-examples-mysqlconnection-connectiontimeout::  Property ConnectionTimeout

Represents an open connection to a MySQL Server database. This class
cannot be inherited.

A `MySqlConnection' object represents a session to a MySQL Server data
source. When you create an instance of `MySqlConnection', all
properties are set to their initial values. For a list of these values,
see the `MySqlConnection' constructor.

If the `MySqlConnection' goes out of scope, it is not closed.
Therefore, you must explicitly close the connection by calling
`MySqlConnection.Close' or `MySqlConnection.Dispose'.

*Examples*

The following example creates a `MySqlCommand' and a `MySqlConnection'.
The `MySqlConnection' is opened and set as the
`MySqlCommand.Connection' for the `MySqlCommand'. The example then calls
`MySqlCommand.ExecuteNonQuery', and closes the connection. To
accomplish this, the `ExecuteNonQuery' is passed a connection string
and a query string that is an SQL INSERT statement.

Visual Basic example:

     Public Sub InsertRow(myConnectionString As String)
       ' If the connection string is null, use a default.
       If myConnectionString = "" Then
         myConnectionString = "Database=Test;Data Source=localhost;User Id=username;Password=pass"
       End If
       Dim myConnection As New MySqlConnection(myConnectionString)
       Dim myInsertQuery As String = "INSERT INTO Orders (id, customerId, amount) Values(1001, 23, 30.66)"
       Dim myCommand As New MySqlCommand(myInsertQuery)
       myCommand.Connection = myConnection
       myConnection.Open()
       myCommand.ExecuteNonQuery()
       myCommand.Connection.Close()
     End Sub

C# example:

     public void InsertRow(string myConnectionString)
     {
       // If the connection string is null, use a default.
       if(myConnectionString == "")
       {
         myConnectionString = "Database=Test;Data Source=localhost;User Id=username;Password=pass";
       }
       MySqlConnection myConnection = new MySqlConnection(myConnectionString);
       string myInsertQuery = "INSERT INTO Orders (id, customerId, amount) Values(1001, 23, 30.66)";
       MySqlCommand myCommand = new MySqlCommand(myInsertQuery);
       myCommand.Connection = myConnection;
       myConnection.Open();
       myCommand.ExecuteNonQuery();
       myCommand.Connection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-defctor,  Next: connector-net-examples-mysqlconnection-ctor1,  Prev: connector-net-examples-mysqlconnection,  Up: connector-net-examples-mysqlconnection

20.2.3.32 Class MySqlConnection Constructor (Default)
.....................................................

Initializes a new instance of the `MySqlConnection' class.

When a new instance of `MySqlConnection' is created, the read/write
properties are set to the following initial values unless they are
specifically set using their associated keywords in the
`ConnectionString' property.

* Properties*                        * Initial Value*
* `ConnectionString' *               * empty string ("")*
* `ConnectionTimeout' *              * 15*
* `Database' *                       * empty string ("")*
* `DataSource' *                     * empty string ("")*
* `ServerVersion' *                  * empty string ("")*

You can change the value for these properties only by using the
`ConnectionString' property.

*Examples*

*Overload methods for MySqlConnection*

Initializes a new instance of the `MySqlConnection' class.


File: manual.info,  Node: connector-net-examples-mysqlconnection-ctor1,  Next: connector-net-examples-mysqlconnection-connectionstring,  Prev: connector-net-examples-mysqlconnection-defctor,  Up: connector-net-examples-mysqlconnection

20.2.3.33 Class MySqlConnection Constructor Form 1
..................................................

Initializes a new instance of the `MySqlConnection' class when given a
string containing the connection string.

When a new instance of `MySqlConnection' is created, the read/write
properties are set to the following initial values unless they are
specifically set using their associated keywords in the
`ConnectionString' property.

* Properties*                        * Initial Value*
* `ConnectionString' *               * empty string ("")*
* `ConnectionTimeout' *              * 15*
* `Database' *                       * empty string ("")*
* `DataSource' *                     * empty string ("")*
* `ServerVersion' *                  * empty string ("")*

You can change the value for these properties only by using the
`ConnectionString' property.

*Examples*

*Parameters:* The connection properties used to open the MySQL database.


File: manual.info,  Node: connector-net-examples-mysqlconnection-connectionstring,  Next: connector-net-examples-mysqlconnection-open,  Prev: connector-net-examples-mysqlconnection-ctor1,  Up: connector-net-examples-mysqlconnection

20.2.3.34 Property ConnectionString
...................................

Gets or sets the string used to connect to a MySQL Server database.

The `ConnectionString' returned may not be exactly like what was
originally set but will be indentical in terms of keyword/value pairs.
Security information will not be included unless the Persist Security
Info value is set to true.

You can use the `ConnectionString' property to connect to a database.
The following example illustrates a typical connection string.

     "Persist Security Info=False;database=MyDB;»
         server=MySqlServer;user id=myUser;Password=myPass"

The `ConnectionString' property can be set only when the connection is
closed. Many of the connection string values have corresponding
read-only properties. When the connection string is set, all of these
properties are updated, except when an error is detected. In this case,
none of the properties are updated.  `MySqlConnection' properties
return only those settings contained in the `ConnectionString'.

To connect to a local machine, specify "localhost" for the server. If
you do not specify a server, localhost is assumed.

Resetting the `ConnectionString' on a closed connection resets all
connection string values (and related properties) including the
password. For example, if you set a connection string that includes
"Database= MyDb", and then reset the connection string to "Data
Source=myserver;User Id=myUser;Password=myPass", the
`MySqlConnection.Database' property is no longer set to MyDb.

The connection string is parsed immediately after being set.  If errors
in syntax are found when parsing, a runtime exception, such as
`ArgumentException', is generated. Other errors can be found only when
an attempt is made to open the connection.

The basic format of a connection string consists of a series of
keyword/value pairs separated by semicolons. The equal sign (`=')
connects each keyword and its value.  Additional notes on setting
values for options:

   * To include values that contain a semicolon, single-quote
     character, or double-quote character, the value must be enclosed
     in double quotes. If the value contains both a semicolon and a
     double-quote character, the value can be enclosed in single
     quotes. The single quote is also useful if the value begins with a
     double-quote character.  Conversely, the double quote can be used
     if the value begins with a single quote. If the value contains both
     single-quote and double-quote characters, the quote character used
     to enclose the value must be doubled each time it occurs within
     the value.

   * To include preceding or trailing spaces in the string value, the
     value must be enclosed in either single quotes or double quotes.
     Any leading or trailing spaces around integer, Boolean, or
     enumerated values are ignored, even if enclosed in quotes.
     However, spaces within a string literal keyword or value are
     preserved. Using .NET Framework version 1.1, single or double
     quotes may be used within a connection string without using
     delimiters (for example, Data Source= my'Server or Data Source=
     my"Server), unless a quote character is the first or last
     character in the value.

   * To include an equal sign (=) in a keyword or value, it must be
     preceded by another equal sign. For example, in the hypothetical
     connection string

          "key==word=value"

     the keyword is "key=word" and the value is "value".

   * If a specific keyword in a keyword= value pair occurs multiple
     times in a connection string, the last occurrence listed is used
     in the value set.

   * Keywords are not case sensitive.

The following table lists the valid names for keyword values within the
`ConnectionString'.

Name                      Default Description
`Connect Timeout',        15      The length of time (in seconds) to wait
`Connection Timeout'              for a connection to the server before
                                  terminating the attempt and generating
                                  an error.
`Host', `Server', `Data   localhostThe name or network address of the
Source', `DataSource',            instance of MySQL to which to connect.
`Address', `Addr',                Multiple hosts can be specified
`Network Address'                 separated by &. This can be useful
                                  where multiple MySQL servers are
                                  configured for replication and you are
                                  not concerned about the precise server
                                  you are connecting to. No attempt is
                                  made by the provider to synchronize
                                  writes to the database so care should
                                  be taken when using this option. In
                                  Unix environment with Mono, this can be
                                  a fully qualified path to MySQL socket
                                  file name. With this configuration, the
                                  Unix socket will be used instead of
                                  TCP/IP socket. Currently only a single
                                  socket name can be given so accessing
                                  MySQL in a replicated environment using
                                  Unix sockets is not currently supported.
`Ignore Prepare'          true    When true, instructs the provider to
                                  ignore any calls to
                                  `MySqlCommand.Prepare()'. This option
                                  is provided to prevent issues with
                                  corruption of the statements when use
                                  with server side prepared statements.
                                  If you want to use server-side prepare
                                  statements, set this option to false.
                                  This option was added in Connector/NET
                                  5.0.3 and Connector/NET 1.0.9.
`Port'                    3306    The port MySQL is using to listen for
                                  connections. This value is ignored if
                                  Unix socket is used.
`Protocol'                socket  Specifies the type of connection to
                                  make to the server. Values can be:
                                  `socket' or `tcp' for a socket
                                  connection, `pipe' for a named pipe
                                  connection, `unix' for a Unix socket
                                  connection, `memory' to use MySQL
                                  shared memory.
`CharSet', `Character             Specifies the character set that should
Set'                              be used to encode all queries sent to
                                  the server. Resultsets are still
                                  returned in the character set of the
                                  data returned.
`Logging'                 false   When true, various pieces of
                                  information is output to any configured
                                  TraceListeners.
`Allow Batch'             true    When true, multiple SQL statements can
                                  be sent with one command execution.
                                  -Note- Starting with MySQL 4.1.1, batch
                                  statements should be separated by the
                                  server-defined separator character.
                                  Commands sent to earlier versions of
                                  MySQL should be separated with ';'.
`Encrypt'                 false   For Connector/NET 5.0.3 and later, when
                                  `true', SSL encryption is used for all
                                  data sent between the client and server
                                  if the server has a certificate
                                  installed. Recognized values are
                                  `true', `false', `yes', and `no'. In
                                  versions before 5.0.3, this option had
                                  no effect.
`Initial Catalog',        mysql   The name of the database to use intially
`Database'                        
`Password', `pwd'                 The password for the MySQL account
                                  being used.
`Persist Security Info'   false   When set to `false' or `no' (strongly
                                  recommended), security-sensitive
                                  information, such as the password, is
                                  not returned as part of the connection
                                  if the connection is open or has ever
                                  been in an open state. Resetting the
                                  connection string resets all connection
                                  string values including the password.
                                  Recognized values are `true', `false',
                                  `yes', and `no'.
`User Id', `Username',            The MySQL login account being used.
`Uid', `User name'                
`Shared Memory Name'      MYSQL   The name of the shared memory object to
                                  use for communication if the connection
                                  protocol is set to memory.
`Allow Zero Datetime'     false   True to have MySqlDataReader.GetValue()
                                  return a MySqlDateTime for date or
                                  datetime columns that have illegal
                                  values. False will cause a
                                  `System.DateTime' object to be returned
                                  for legal values and an exception will
                                  be thrown for illegal values.
`Convert Zero Datetime'   false   True to have
                                  `MySqlDataReader.GetValue()' and
                                  `MySqlDataReader.GetDateTime()' return
                                  DateTime.MinValue for date or datetime
                                  columns that have illegal values.
`Old Syntax', `OldSyntax' false   Allows use of '@' symbol as a parameter
                                  marker. See `MySqlCommand' for more
                                  info. This option was deprecated in
                                  Connector/NET 5.2.2. All future code
                                  should be written using the '@' symbol.
`Pipe Name', `Pipe'       mysql   When set to the name of a named pipe,
                                  the `MySqlConnection' will attempt to
                                  connect to MySQL on that named
                                  pipe.This settings only applies to the
                                  Windows platform.
`Procedure Cache'         25      Sets the size of the stored procedure
                                  cache. By default, Connector/NET will
                                  store the metadata (input/output
                                  datatypes) about the last 25 stored
                                  procedures used. To disable the stored
                                  procedure cache, set the value to zero
                                  (0).  This option was added in
                                  Connector/NET 5.0.2 and Connector/NET
                                  1.0.9.
`Use Procedure Bodies'    true    Setting this option to `false'
                                  indicates that the user connecting to
                                  the database does not have the `SELECT'
                                  privileges for the `mysql.proc' (stored
                                  procedures) table. When to set to
                                  `false', Connector/NET will not rely on
                                  this information being available when
                                  the procedure is called. Because
                                  Connector/NET will be unable to
                                  determine this information, you should
                                  explicitly set the types of the all the
                                  parameters before the call and the
                                  parameters should be added to the
                                  command in the exact same order as they
                                  appear in the procedure definition.
                                  This option was added in Connector/NET
                                  5.0.4 and Connector/NET 1.0.10.
`default command timeout'         Sets the default value of the command
                                  timeout to be used. This does not
                                  supercede the individual command
                                  timeout property on an individual
                                  command object. If you set the command
                                  timeout property, that will be used.
                                  This option was added in Connector/NET
                                  5.1.4
`Treat Tiny As Boolean'   true    Setting this value to `false' indicates
                                  that `TINYINT(1)' will be treated as an
                                  *Note `INT': numeric-types. See also
                                  *Note numeric-type-overview:: for a
                                  further explanation of the *Note
                                  `TINYINT': numeric-types. and *Note
                                  `BOOL': numeric-types. data types.
`Allow User Variables'    false   Setting this to `true' indicates that
                                  the provider expects user variables in
                                  the SQL. This option was added in
                                  Connector/NET version 5.2.2.
`Respect Binary Flags'    true    Setting this option to `false' means
                                  that Connector/NET will ignore a
                                  column's binary flags as set by the
                                  server. This option was added in
                                  Connector/NET version 5.1.3.
`Use Compression'         false   Setting this option to `true' enables
                                  compression of packets exchanged
                                  between the client and the server. This
                                  exchange is defined by the MySQL
                                  client-server protocol.
                                  
                                  Compression is used if both client and
                                  server support ZLIB compression, and
                                  the client has requested compression
                                  using this option.
                                  
                                  A compressed packet header is: packet
                                  length (3 bytes), packet number (1
                                  byte), and Uncompressed Packet Length
                                  (3 bytes). The Uncompressed Packet
                                  Length is the number of bytes in the
                                  original, uncompressed packet. If this
                                  is zero then the data in this packet
                                  has not been compressed. When the
                                  compression protocol is in use, either
                                  the client or the server may compress
                                  packets. However, compression will not
                                  occur if the compressed length is
                                  greater than the original length. Thus,
                                  some packets will contain compressed
                                  data while other packets will not.
`Use Affected Rows'       false   When `true' the connection will report
                                  changed rows instead of found rows.
                                  This option was added in Connector/NET
                                  version 5.2.6.

The following table lists the valid names for connection pooling values
within the `ConnectionString'.  For more information about connection
pooling, see Connection Pooling for the MySQL Data Provider.

Name                      Default Description
`Connection Lifetime'     0       When a connection is returned to the
                                  pool, its creation time is compared
                                  with the current time, and the
                                  connection is destroyed if that time
                                  span (in seconds) exceeds the value
                                  specified by `Connection Lifetime'.
                                  This is useful in clustered
                                  configurations to force load balancing
                                  between a running server and a server
                                  just brought online. A value of zero
                                  (0) causes pooled connections to have
                                  the maximum connection timeout.
`Max Pool Size'           100     The maximum number of connections
                                  allowed in the pool.
`Min Pool Size'           0       The minimum number of connections
                                  allowed in the pool.
`Pooling'                 true    When `true', the `MySqlConnection'
                                  object is drawn from the appropriate
                                  pool, or if necessary, is created and
                                  added to the appropriate pool.
                                  Recognized values are `true', `false',
                                  `yes', and `no'.
`Reset Pooled             true    Specifies whether a ping and a reset
Connections',                     should be sent to the server before a
`ResetConnections',               pooled connection is returned. Not
`ResetPooledConnections'          resetting will yield faster connection
                                  opens but also will not clear out
                                  session items such as temp tables.
`Cache Server             false   Specifies whether server variables
Configuration',                   should be updated when a pooled
`CacheServerConfiguration',        connection is returned. Turning this
`CacheServerConfig'               one will yeild faster opens but will
                                  also not catch any server changes made
                                  by other connections.

When setting keyword or connection pooling values that require a
Boolean value, you can use 'yes' instead of 'true', and 'no' instead of
'false'.

*Note*:

The MySQL Data Provider uses the native socket protocol to communicate
with MySQL. Therefore, it does not support the use of an ODBC data
source name (DSN) when connecting to MySQL because it does not add an
ODBC layer.

*Caution*:

In this release, the application should use caution when constructing a
connection string based on user input (for example when retrieving user
ID and password information from a dialog box, and appending it to the
connection string). The application should ensure that a user cannot
embed extra connection string parameters in these values (for example,
entering a password as "validpassword;database=somedb" in an attempt to
attach to a different database).

*Examples*

The following example creates a `MySqlConnection' and sets some of its
properties

Visual Basic example:

     Public Sub CreateConnection()
       Dim myConnection As New MySqlConnection()
       myConnection.ConnectionString = "Persist Security Info=False;database=myDB;server=myHost;Connect Timeout=30;user id=myUser; pwd=myPass"
       myConnection.Open()
     End Sub 'CreateConnection

C# example:

     public void CreateConnection()
     {
       MySqlConnection myConnection = new MySqlConnection();
       myConnection.ConnectionString = "Persist Security Info=False;database=myDB;server=myHost;Connect Timeout=30;user id=myUser; pwd=myPass";
       myConnection.Open();
     }

*Examples*

The following example creates a `MySqlConnection' in Unix environment
with Mono installed. MySQL socket file name used in this example is
"/var/lib/mysql/mysql.sock". The actual file name depends on your MySQL
configuration.

Visual Basic example:

     Public Sub CreateConnection()
       Dim myConnection As New MySqlConnection()
       myConnection.ConnectionString = "database=myDB;server=/var/lib/mysql/mysql.sock;user id=myUser; pwd=myPass"
       myConnection.Open()
     End Sub 'CreateConnection

C# example:

     public void CreateConnection()
     {
       MySqlConnection myConnection = new MySqlConnection();
       myConnection.ConnectionString = "database=myDB;server=/var/lib/mysql/mysql.sock;user id=myUser; pwd=myPass";
       myConnection.Open();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-open,  Next: connector-net-examples-mysqlconnection-database,  Prev: connector-net-examples-mysqlconnection-connectionstring,  Up: connector-net-examples-mysqlconnection

20.2.3.35 Method Open
.....................

Opens a database connection with the property settings specified by the
ConnectionString.

*Exception:* Cannot open a connection without specifying a data source
or server.

*Exception:* A connection-level error occurred while opening the
connection.

The `MySqlConnection' draws an open connection from the connection pool
if one is available.  Otherwise, it establishes a new connection to an
instance of MySQL.

*Examples*

The following example creates a `MySqlConnection', opens it, displays
some of its properties, then closes the connection.

Visual Basic example:

     Public Sub CreateMySqlConnection(myConnString As String)
       Dim myConnection As New MySqlConnection(myConnString)
       myConnection.Open()
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.Cr + "State: " + myConnection.State.ToString())
       myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion +
               "\nState: " + myConnection.State.ToString());
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-database,  Next: connector-net-examples-mysqlconnection-state,  Prev: connector-net-examples-mysqlconnection-open,  Up: connector-net-examples-mysqlconnection

20.2.3.36 Property Database
...........................

Gets the name of the current database or the database to be used after
a connection is opened.

*Returns:* The name of the current database or the name of the database
to be used after a connection is opened. The default value is an empty
string.

The `Database' property does not update dynamically. If you change the
current database using an SQL statement, then this property may reflect
the wrong value. If you change the current database using the
`ChangeDatabase' method, this property is updated to reflect the new
database.

*Examples*

The following example creates a `MySqlConnection' and displays some of
its read-only properties.

Visual Basic example:

     Public Sub CreateMySqlConnection()
       Dim myConnString As String = _
         "Persist Security Info=False;database=test;server=localhost;user id=joeuser;pwd=pass"
       Dim myConnection As New MySqlConnection( myConnString )
       myConnection.Open()
       MessageBox.Show( "Server Version: " + myConnection.ServerVersion _
         + ControlChars.NewLine + "Database: " + myConnection.Database )
       myConnection.ChangeDatabase( "test2" )
       MessageBox.Show( "ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.NewLine + "Database: " + myConnection.Database )
       myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection()
     {
       string myConnString =
         "Persist Security Info=False;database=test;server=localhost;user id=joeuser;pwd=pass";
       MySqlConnection myConnection = new MySqlConnection( myConnString );
       myConnection.Open();
       MessageBox.Show( "Server Version: " + myConnection.ServerVersion
         + "\nDatabase: " + myConnection.Database );
       myConnection.ChangeDatabase( "test2" );
       MessageBox.Show( "ServerVersion: " + myConnection.ServerVersion
         + "\nDatabase: " + myConnection.Database );
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-state,  Next: connector-net-examples-mysqlconnection-serverversion,  Prev: connector-net-examples-mysqlconnection-database,  Up: connector-net-examples-mysqlconnection

20.2.3.37 Property State
........................

Gets the current state of the connection.

*Returns:* A bitwise combination of the `System.Data.ConnectionState'
values. The default is `Closed'.

The allowed state changes are:

   * From `Closed' to `Open', using the `Open' method of the connection
     object.

   * From `Open' to `Closed', using either the `Close' method or the
     `Dispose' method of the connection object.

*Examples*

The following example creates a `MySqlConnection', opens it, displays
some of its properties, then closes the connection.

Visual Basic example:

     Public Sub CreateMySqlConnection(myConnString As String)
       Dim myConnection As New MySqlConnection(myConnString)
       myConnection.Open()
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.Cr + "State: " + myConnection.State.ToString())
       myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion +
               "\nState: " + myConnection.State.ToString());
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-serverversion,  Next: connector-net-examples-mysqlconnection-close,  Prev: connector-net-examples-mysqlconnection-state,  Up: connector-net-examples-mysqlconnection

20.2.3.38 Property ServerVersion
................................

Gets a string containing the version of the MySQL server to which the
client is connected.

*Returns:* The version of the instance of MySQL.

*Exception:* The connection is closed.

*Examples*

The following example creates a `MySqlConnection', opens it, displays
some of its properties, then closes the connection.

Visual Basic example:

     Public Sub CreateMySqlConnection(myConnString As String)
       Dim myConnection As New MySqlConnection(myConnString)
       myConnection.Open()
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.Cr + "State: " + myConnection.State.ToString())
       myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion +
               "\nState: " + myConnection.State.ToString());
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-close,  Next: connector-net-examples-mysqlconnection-createcommand,  Prev: connector-net-examples-mysqlconnection-serverversion,  Up: connector-net-examples-mysqlconnection

20.2.3.39 Method Close
......................

Closes the connection to the database. This is the preferred method of
closing any open connection.

The `Close' method rolls back any pending transactions. It then
releases the connection to the connection pool, or closes the
connection if connection pooling is disabled.

An application can call `Close' more than one time. No exception is
generated.

*Examples*

The following example creates a `MySqlConnection', opens it, displays
some of its properties, then closes the connection.

Visual Basic example:

     Public Sub CreateMySqlConnection(myConnString As String)
       Dim myConnection As New MySqlConnection(myConnString)
       myConnection.Open()
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.Cr + "State: " + myConnection.State.ToString())
       myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion +
               "\nState: " + myConnection.State.ToString());
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-createcommand,  Next: connector-net-examples-mysqlconnection-begintransaction,  Prev: connector-net-examples-mysqlconnection-close,  Up: connector-net-examples-mysqlconnection

20.2.3.40 Method CreateCommand
..............................

Creates and returns a `MySqlCommand' object associated with the
`MySqlConnection'.

*Returns:* A `MySqlCommand' object.


File: manual.info,  Node: connector-net-examples-mysqlconnection-begintransaction,  Next: connector-net-examples-mysqlconnection-begintransaction1,  Prev: connector-net-examples-mysqlconnection-createcommand,  Up: connector-net-examples-mysqlconnection

20.2.3.41 Method BeginTransaction
.................................

Begins a database transaction.

*Returns:* An object representing the new transaction.

*Exception:* Parallel transactions are not supported.

This command is equivalent to the MySQL BEGIN TRANSACTION command.

You must explicitly commit or roll back the transaction using the
`MySqlTransaction.Commit' or `MySqlTransaction.Rollback' method.

*Note*:

If you do not specify an isolation level, the default isolation level
is used. To specify an isolation level with the `BeginTransaction'
method, use the overload that takes the `iso' parameter.

*Examples*

The following example creates a `MySqlConnection' and a
`MySqlTransaction'. It also demonstrates how to use the
`BeginTransaction', a `MySqlTransaction.Commit', and
`MySqlTransaction.Rollback' methods.

Visual Basic example:

     Public Sub RunTransaction(myConnString As String)
       Dim myConnection As New MySqlConnection(myConnString)
       myConnection.Open()

       Dim myCommand As MySqlCommand = myConnection.CreateCommand()
       Dim myTrans As MySqlTransaction

       ' Start a local transaction
       myTrans = myConnection.BeginTransaction()
       ' Must assign both transaction object and connection
       ' to Command object for a pending local transaction
       myCommand.Connection = myConnection
       myCommand.Transaction = myTrans

       Try
         myCommand.CommandText = "Insert into Test (id, desc) VALUES (100, 'Description')"
         myCommand.ExecuteNonQuery()
         myCommand.CommandText = "Insert into Test (id, desc) VALUES (101, 'Description')"
         myCommand.ExecuteNonQuery()
         myTrans.Commit()
         Console.WriteLine("Both records are written to database.")
       Catch e As Exception
         Try
           myTrans.Rollback()
         Catch ex As MySqlException
           If Not myTrans.Connection Is Nothing Then
             Console.WriteLine("An exception of type " + ex.GetType().ToString() + _
                               " was encountered while attempting to roll back the transaction.")
           End If
         End Try

         Console.WriteLine("An exception of type " + e.GetType().ToString() + _
                         "was encountered while inserting the data.")
         Console.WriteLine("Neither record was written to database.")
       Finally
         myConnection.Close()
       End Try
     End Sub

C# example:

     public void RunTransaction(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MySqlCommand myCommand = myConnection.CreateCommand();
       MySqlTransaction myTrans;
       // Start a local transaction
       myTrans = myConnection.BeginTransaction();
       // Must assign both transaction object and connection
       // to Command object for a pending local transaction
       myCommand.Connection = myConnection;
       myCommand.Transaction = myTrans;
         try
         {
           myCommand.CommandText = "insert into Test (id, desc) VALUES (100, 'Description')";
           myCommand.ExecuteNonQuery();
           myCommand.CommandText = "insert into Test (id, desc) VALUES (101, 'Description')";
           myCommand.ExecuteNonQuery();
           myTrans.Commit();
           Console.WriteLine("Both records are written to database.");
         }
         catch(Exception e)
         {
           try
           {
             myTrans.Rollback();
           }
           catch (SqlException ex)
           {
             if (myTrans.Connection != null)
             {
               Console.WriteLine("An exception of type " + ex.GetType() +
                                 " was encountered while attempting to roll back the transaction.");
             }
           }

           Console.WriteLine("An exception of type " + e.GetType() +
                             " was encountered while inserting the data.");
           Console.WriteLine("Neither record was written to database.");
         }
         finally
         {
           myConnection.Close();
         }
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-begintransaction1,  Next: connector-net-examples-mysqlconnection-changedatabase,  Prev: connector-net-examples-mysqlconnection-begintransaction,  Up: connector-net-examples-mysqlconnection

20.2.3.42 Method BeginTransaction (overload)
............................................

Begins a database transaction with the specified isolation level.

*Parameters:* The isolation level under which the transaction should
run.

*Returns:* An object representing the new transaction.

*Exception:* Parallel exceptions are not supported.

This command is equivalent to the MySQL BEGIN TRANSACTION command.

You must explicitly commit or roll back the transaction using the
`MySqlTransaction.Commit' or `MySqlTransaction.Rollback' method.

*Note*:

If you do not specify an isolation level, the default isolation level
is used. To specify an isolation level with the `BeginTransaction'
method, use the overload that takes the `iso' parameter.

*Examples*

The following example creates a `MySqlConnection' and a
`MySqlTransaction'. It also demonstrates how to use the
`BeginTransaction', a `MySqlTransaction.Commit', and
`MySqlTransaction.Rollback' methods.

Visual Basic example:

     Public Sub RunTransaction(myConnString As String)
       Dim myConnection As New MySqlConnection(myConnString)
       myConnection.Open()

       Dim myCommand As MySqlCommand = myConnection.CreateCommand()
       Dim myTrans As MySqlTransaction

       ' Start a local transaction
       myTrans = myConnection.BeginTransaction()
       ' Must assign both transaction object and connection
       ' to Command object for a pending local transaction
       myCommand.Connection = myConnection
       myCommand.Transaction = myTrans

       Try
         myCommand.CommandText = "Insert into Test (id, desc) VALUES (100, 'Description')"
         myCommand.ExecuteNonQuery()
         myCommand.CommandText = "Insert into Test (id, desc) VALUES (101, 'Description')"
         myCommand.ExecuteNonQuery()
         myTrans.Commit()
         Console.WriteLine("Both records are written to database.")
       Catch e As Exception
         Try
           myTrans.Rollback()
         Catch ex As MySqlException
           If Not myTrans.Connection Is Nothing Then
             Console.WriteLine("An exception of type " + ex.GetType().ToString() + _
                               " was encountered while attempting to roll back the transaction.")
           End If
         End Try

         Console.WriteLine("An exception of type " + e.GetType().ToString() + _
                         "was encountered while inserting the data.")
         Console.WriteLine("Neither record was written to database.")
       Finally
         myConnection.Close()
       End Try
     End Sub

C# example:

     public void RunTransaction(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MySqlCommand myCommand = myConnection.CreateCommand();
       MySqlTransaction myTrans;
       // Start a local transaction
       myTrans = myConnection.BeginTransaction();
       // Must assign both transaction object and connection
       // to Command object for a pending local transaction
       myCommand.Connection = myConnection;
       myCommand.Transaction = myTrans;
         try
         {
           myCommand.CommandText = "insert into Test (id, desc) VALUES (100, 'Description')";
           myCommand.ExecuteNonQuery();
           myCommand.CommandText = "insert into Test (id, desc) VALUES (101, 'Description')";
           myCommand.ExecuteNonQuery();
           myTrans.Commit();
           Console.WriteLine("Both records are written to database.");
         }
         catch(Exception e)
         {
           try
           {
             myTrans.Rollback();
           }
           catch (SqlException ex)
           {
             if (myTrans.Connection != null)
             {
               Console.WriteLine("An exception of type " + ex.GetType() +
                                 " was encountered while attempting to roll back the transaction.");
             }
           }

           Console.WriteLine("An exception of type " + e.GetType() +
                             " was encountered while inserting the data.");
           Console.WriteLine("Neither record was written to database.");
         }
         finally
         {
           myConnection.Close();
         }
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-changedatabase,  Next: connector-net-examples-mysqlconnection-statechange,  Prev: connector-net-examples-mysqlconnection-begintransaction1,  Up: connector-net-examples-mysqlconnection

20.2.3.43 Method ChangeDatabase
...............................

Changes the current database for an open MySqlConnection.

*Parameters:* The name of the database to use.

The value supplied in the `database' parameter must be a valid database
name. The `database' parameter cannot contain a null value, an empty
string, or a string with only blank characters.

When you are using connection pooling against MySQL, and you close the
connection, it is returned to the connection pool.  The next time the
connection is retrieved from the pool, the reset connection request
executes before the user performs any operations.

MySQL Enterprise

MySQL Enterprise subscribers will find more information on this subject
in the Knowledge Base article, Understanding and Using Connection
Pooling (https://kb.mysql.com/view.php?id=4918). Access to the MySQL
Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. To subscribe see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Exception:* The database name is not valid.

*Exception:* The connection is not open.

*Exception:* Cannot change the database.

*Examples*

The following example creates a `MySqlConnection' and displays some of
its read-only properties.

Visual Basic example:

     Public Sub CreateMySqlConnection()
       Dim myConnString As String = _
         "Persist Security Info=False;database=test;server=localhost;user id=joeuser;pwd=pass"
       Dim myConnection As New MySqlConnection( myConnString )
       myConnection.Open()
       MessageBox.Show( "Server Version: " + myConnection.ServerVersion _
         + ControlChars.NewLine + "Database: " + myConnection.Database )
       myConnection.ChangeDatabase( "test2" )
       MessageBox.Show( "ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.NewLine + "Database: " + myConnection.Database )
       myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection()
     {
       string myConnString =
         "Persist Security Info=False;database=test;server=localhost;user id=joeuser;pwd=pass";
       MySqlConnection myConnection = new MySqlConnection( myConnString );
       myConnection.Open();
       MessageBox.Show( "Server Version: " + myConnection.ServerVersion
         + "\nDatabase: " + myConnection.Database );
       myConnection.ChangeDatabase( "test2" );
       MessageBox.Show( "ServerVersion: " + myConnection.ServerVersion
         + "\nDatabase: " + myConnection.Database );
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-statechange,  Next: connector-net-examples-mysqlconnection-infomessage,  Prev: connector-net-examples-mysqlconnection-changedatabase,  Up: connector-net-examples-mysqlconnection

20.2.3.44 Event Handler StateChange
...................................

Occurs when the state of the connection changes.

The `StateChange' event fires whenever the `State' changes from closed
to opened, or from opened to closed. `StateChange' fires immediately
after the `MySqlConnection' transitions.

If an event handler throws an exception from within the `StateChange'
event, the exception propagates to the caller of the `Open' or `Close'
method.

The `StateChange' event is not raised unless you explicitly call
`Close' or `Dispose'.

The event handler receives an argument of type
`System.Data.StateChangeEventArgs' containing data related to this
event. The following `StateChangeEventArgs' properties provide
information specific to this event.

* Property*                          Description
*                                    Gets the new state of the
`System.Data.StateChangeEventArgs.CurrentState'connection. The connection object
*                                    will be in the new state already
                                     when the event is fired.
*                                    Gets the original state of the
`System.Data.StateChangeEventArgs.OriginalState'connection.
*                                    


File: manual.info,  Node: connector-net-examples-mysqlconnection-infomessage,  Next: connector-net-examples-mysqlconnection-connectiontimeout,  Prev: connector-net-examples-mysqlconnection-statechange,  Up: connector-net-examples-mysqlconnection

20.2.3.45 Event Handler InfoMessage
...................................

Occurs when MySQL returns warnings as a result of executing a command
or query.


File: manual.info,  Node: connector-net-examples-mysqlconnection-connectiontimeout,  Prev: connector-net-examples-mysqlconnection-infomessage,  Up: connector-net-examples-mysqlconnection

20.2.3.46 Property ConnectionTimeout
....................................

Gets the time to wait while trying to establish a connection before
terminating the attempt and generating an error.

*Exception:* The value set is less than 0.

A value of 0 indicates no limit, and should be avoided in a
`MySqlConnection.ConnectionString' because an attempt to connect will
wait indefinitely.

*Examples*

The following example creates a MySqlConnection and sets some of its
properties in the connection string.

Visual Basic example:

     Public Sub CreateSqlConnection()
       Dim myConnection As New MySqlConnection()
       myConnection.ConnectionString = "Persist Security Info=False;Username=user;Password=pass;database=test1;server=localhost;Connect Timeout=30"
       myConnection.Open()
     End Sub

C# example:

     public void CreateSqlConnection()
     {
       MySqlConnection myConnection = new MySqlConnection();
       myConnection.ConnectionString = "Persist Security Info=False;Username=user;»
           Password=pass;database=test1;server=localhost;Connect Timeout=30";
       myConnection.Open();
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter,  Next: connector-net-examples-mysqldatareader,  Prev: connector-net-examples-mysqlconnection,  Up: connector-net-examples

20.2.3.47 Using MySqlDataAdapter
................................

* Menu:

* connector-net-examples-mysqldataadapter-ctor::  Class MySqlDataAdapter Constructor
* connector-net-examples-mysqldataadapter-ctor1::  Class MySqlDataAdapter Constructor Form 1
* connector-net-examples-mysqldataadapter-ctor2::  Class MySqlDataAdapter Constructor Form 2
* connector-net-examples-mysqldataadapter-ctor3::  Class MySqlDataAdapter Constructor Form 3
* connector-net-examples-mysqldataadapter-deletecommand::  Property DeleteCommand
* connector-net-examples-mysqldataadapter-insertcommand::  Property InsertCommand
* connector-net-examples-mysqldataadapter-updatecommand::  Property UpdateCommand
* connector-net-examples-mysqldataadapter-selectcommand::  Property SelectCommand

Represents a set of data commands and a database connection that are
used to fill a data set and update a MySQL database. This class cannot
be inherited.

The `MySQLDataAdapter', serves as a bridge between a
`System.Data.DataSet' and MySQL for retrieving and saving data. The
`MySQLDataAdapter' provides this bridge by mapping
`DbDataAdapter.Fill', which changes the data in the `DataSet' to match
the data in the data source, and `DbDataAdapter.Update', which changes
the data in the data source to match the data in the `DataSet', using
the appropriate SQL statements against the data source.

When the `MySQLDataAdapter' fills a `DataSet', it will create the
necessary tables and columns for the returned data if they do not
already exist.  However, primary key information will not be included
in the implicitly created schema unless the
`System.Data.MissingSchemaAction' property is set to
`System.Data.MissingSchemaAction.AddWithKey'.  You may also have the
`MySQLDataAdapter' create the schema of the `DataSet', including primary
key information, before filling it with data using
`System.Data.Common.DbDataAdapter.FillSchema'.

`MySQLDataAdapter' is used in conjunction with `MySqlConnection' and
`MySqlCommand' to increase performance when connecting to a MySQL
database.

The `MySQLDataAdapter' also includes the
`MySqlDataAdapter.SelectCommand', `MySqlDataAdapter.InsertCommand',
`MySqlDataAdapter.DeleteCommand', `MySqlDataAdapter.UpdateCommand', and
`DataAdapter.TableMappings' properties to facilitate the loading and
updating of data.

When an instance of `MySQLDataAdapter' is created, the read/write
properties are set to initial values.  For a list of these values, see
the `MySQLDataAdapter' constructor.

*Note*:

Please be aware that the `DataColumn' class in .NET only allows columns
with type of Int16, Int32, or Int64 to be autoincrement columns. If you
plan to use autoincremement columns with MySQL, you should consider
using signed integer columns.

*Examples*

The following example creates a `MySqlCommand' and a `MySqlConnection'.
The `MySqlConnection' is opened and set as the
`MySqlCommand.Connection' for the `MySqlCommand'. The example then calls
`MySqlCommand.ExecuteNonQuery', and closes the connection. To
accomplish this, the `ExecuteNonQuery' is passed a connection string
and a query string that is an SQL INSERT statement.

Visual Basic example:

     Public Function SelectRows(dataSet As DataSet, connection As String, query As String) As DataSet
       Dim conn As New MySqlConnection(connection)
       Dim adapter As New MySqlDataAdapter()
       adapter.SelectCommand = new MySqlCommand(query, conn)
       adapter.Fill(dataset)
       Return dataset
     End Function

C# example:

     public DataSet SelectRows(DataSet dataset,string connection,string query)
     {
       MySqlConnection conn = new MySqlConnection(connection);
       MySqlDataAdapter adapter = new MySqlDataAdapter();
       adapter.SelectCommand = new MySqlCommand(query, conn);
       adapter.Fill(dataset);
       return dataset;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-ctor,  Next: connector-net-examples-mysqldataadapter-ctor1,  Prev: connector-net-examples-mysqldataadapter,  Up: connector-net-examples-mysqldataadapter

20.2.3.48 Class MySqlDataAdapter Constructor
............................................

*Overload methods for MySqlDataAdapter*

Initializes a new instance of the MySqlDataAdapter class.

When an instance of `MySqlDataAdapter' is created, the following
read/write properties are set to the following initial values.

* Properties*                        * Initial Value*
* `MissingMappingAction' *           * `MissingMappingAction.Passthrough'
                                     *
* `MissingSchemaAction' *            * `MissingSchemaAction.Add' *

You can change the value of any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlDataAdapter' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateSqlDataAdapter()
       Dim conn As MySqlConnection = New MySqlConnection("Data Source=localhost;" & _
         "database=test")
       Dim da As MySqlDataAdapter = New MySqlDataAdapter
       da.MissingSchemaAction = MissingSchemaAction.AddWithKey

       da.SelectCommand = New MySqlCommand("SELECT id, name FROM mytable", conn)
       da.InsertCommand = New MySqlCommand("INSERT INTO mytable (id, name) " & _
                                                 "VALUES (@id, @name)", conn)
       da.UpdateCommand = New MySqlCommand("UPDATE mytable SET id=@id, name=@name " & _
                                                 "WHERE id=@oldId", conn)
       da.DeleteCommand = New MySqlCommand("DELETE FROM mytable WHERE id=@id", conn)
       da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
       da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")

       da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
       da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")
       da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
       da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
     End Sub

C# example:

     public static void CreateSqlDataAdapter()
     {
       MySqlConnection conn = new MySqlConnection("Data Source=localhost;database=test");
       MySqlDataAdapter da = new MySqlDataAdapter();
       da.MissingSchemaAction = MissingSchemaAction.AddWithKey;

       da.SelectCommand = new MySqlCommand("SELECT id, name FROM mytable", conn);
       da.InsertCommand = new MySqlCommand("INSERT INTO mytable (id, name) " +
                                                 "VALUES (@id, @name)", conn);
       da.UpdateCommand = new MySqlCommand("UPDATE mytable SET id=@id, name=@name " +
                                                 "WHERE id=@oldId", conn);
       da.DeleteCommand = new MySqlCommand("DELETE FROM mytable WHERE id=@id", conn);
       da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
       da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");

       da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
       da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");
       da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
       da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-ctor1,  Next: connector-net-examples-mysqldataadapter-ctor2,  Prev: connector-net-examples-mysqldataadapter-ctor,  Up: connector-net-examples-mysqldataadapter

20.2.3.49 Class MySqlDataAdapter Constructor Form 1
...................................................

Initializes a new instance of the `MySqlDataAdapter' class with the
specified `MySqlCommand' as the `SelectCommand' property.

*Parameters:* `MySqlCommand' that is an SQL *Note `SELECT': select.
statement or stored procedure and is set as the `SelectCommand'
property of the `MySqlDataAdapter'.

When an instance of `MySqlDataAdapter' is created, the following
read/write properties are set to the following initial values.

* Properties*                        * Initial Value*
* `MissingMappingAction' *           * `MissingMappingAction.Passthrough'
                                     *
* `MissingSchemaAction' *            * `MissingSchemaAction.Add' *

You can change the value of any of these properties through a separate
call to the property.

When `SelectCommand' (or any of the other command properties) is
assigned to a previously created `MySqlCommand', the `MySqlCommand' is
not cloned. The `SelectCommand' maintains a reference to the previously
created `MySqlCommand' object.

*Examples*

The following example creates a `MySqlDataAdapter' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateSqlDataAdapter()
       Dim conn As MySqlConnection = New MySqlConnection("Data Source=localhost;" & _
         "database=test")
       Dim cmd as new MySqlCommand("SELECT id, name FROM mytable", conn)
       Dim da As MySqlDataAdapter = New MySqlDataAdapter(cmd)
       da.MissingSchemaAction = MissingSchemaAction.AddWithKey

       da.InsertCommand = New MySqlCommand("INSERT INTO mytable (id, name) " & _
                                                 "VALUES (@id, @name)", conn)
       da.UpdateCommand = New MySqlCommand("UPDATE mytable SET id=@id, name=@name " & _
                                                 "WHERE id=@oldId", conn)
       da.DeleteCommand = New MySqlCommand("DELETE FROM mytable WHERE id=@id", conn)
       da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
       da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")

       da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
       da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")
       da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
       da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
     End Sub

C# example:

     public static void CreateSqlDataAdapter()
     {
       MySqlConnection conn = new MySqlConnection("Data Source=localhost;database=test");
       MySqlCommand cmd = new MySqlCommand("SELECT id, name FROM mytable", conn);
       MySqlDataAdapter da = new MySqlDataAdapter(cmd);
       da.MissingSchemaAction = MissingSchemaAction.AddWithKey;

       da.InsertCommand = new MySqlCommand("INSERT INTO mytable (id, name) " +
                                             "VALUES (@id, @name)", conn);
       da.UpdateCommand = new MySqlCommand("UPDATE mytable SET id=@id, name=@name " +
                                             "WHERE id=@oldId", conn);
       da.DeleteCommand = new MySqlCommand("DELETE FROM mytable WHERE id=@id", conn);
       da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
       da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");

       da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
       da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");
       da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
       da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-ctor2,  Next: connector-net-examples-mysqldataadapter-ctor3,  Prev: connector-net-examples-mysqldataadapter-ctor1,  Up: connector-net-examples-mysqldataadapter

20.2.3.50 Class MySqlDataAdapter Constructor Form 2
...................................................

Initializes a new instance of the `MySqlDataAdapter' class with a
`SelectCommand' and a `MySqlConnection' object.

*Parameters:* A `String' that is an SQL *Note `SELECT': select.
statement or stored procedure to be used by the `SelectCommand'
property of the `MySqlDataAdapter'.

*Parameters:* A `MySqlConnection' that represents the connection.

This implementation of the `MySqlDataAdapter' opens and closes a
`MySqlConnection' if it is not already open. This can be useful in a an
application that must call the `DbDataAdapter.Fill' method for two or
more `MySqlDataAdapter' objects. If the `MySqlConnection' is already
open, you must explicitly call `MySqlConnection.Close' or
`MySqlConnection.Dispose' to close it.

When an instance of `MySqlDataAdapter' is created, the following
read/write properties are set to the following initial values.

* Properties*                        * Initial Value*
* `MissingMappingAction' *           * `MissingMappingAction.Passthrough'
                                     *
* `MissingSchemaAction' *            * `MissingSchemaAction.Add' *

You can change the value of any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlDataAdapter' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateSqlDataAdapter()
       Dim conn As MySqlConnection = New MySqlConnection("Data Source=localhost;" & _
         "database=test")
       Dim da As MySqlDataAdapter = New MySqlDataAdapter("SELECT id, name FROM mytable", conn)
       da.MissingSchemaAction = MissingSchemaAction.AddWithKey

       da.InsertCommand = New MySqlCommand("INSERT INTO mytable (id, name) " & _
                                                 "VALUES (@id, @name)", conn)
       da.UpdateCommand = New MySqlCommand("UPDATE mytable SET id=@id, name=@name " & _
                                                 "WHERE id=@oldId", conn)
       da.DeleteCommand = New MySqlCommand("DELETE FROM mytable WHERE id=@id", conn)
       da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
       da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")

       da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
       da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")
       da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
       da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
     End Sub

C# example:

     public static void CreateSqlDataAdapter()
     {
       MySqlConnection conn = new MySqlConnection("Data Source=localhost;database=test");
       MySqlDataAdapter da = new MySqlDataAdapter("SELECT id, name FROM mytable", conn);
       da.MissingSchemaAction = MissingSchemaAction.AddWithKey;

       da.InsertCommand = new MySqlCommand("INSERT INTO mytable (id, name) " +
                                         "VALUES (@id, @name)", conn);
       da.UpdateCommand = new MySqlCommand("UPDATE mytable SET id=@id, name=@name " +
                                         "WHERE id=@oldId", conn);
       da.DeleteCommand = new MySqlCommand("DELETE FROM mytable WHERE id=@id", conn);
       da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
       da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");

       da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
       da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");
       da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
       da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-ctor3,  Next: connector-net-examples-mysqldataadapter-deletecommand,  Prev: connector-net-examples-mysqldataadapter-ctor2,  Up: connector-net-examples-mysqldataadapter

20.2.3.51 Class MySqlDataAdapter Constructor Form 3
...................................................

Initializes a new instance of the `MySqlDataAdapter' class with a
`SelectCommand' and a connection string.

*Parameters:* A `string' that is an SQL *Note `SELECT': select.
statement or stored procedure to be used by the `SelectCommand'
property of the `MySqlDataAdapter'.

*Parameters:* The connection string

When an instance of `MySqlDataAdapter' is created, the following
read/write properties are set to the following initial values.

* Properties*                        * Initial Value*
* `MissingMappingAction' *           * `MissingMappingAction.Passthrough'
                                     *
* `MissingSchemaAction' *            * `MissingSchemaAction.Add' *

You can change the value of any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlDataAdapter' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateSqlDataAdapter()
       Dim da As MySqlDataAdapter = New MySqlDataAdapter("SELECT id, name FROM mytable", "Data Source=localhost;database=test")
       Dim conn As MySqlConnection = da.SelectCommand.Connection
       da.MissingSchemaAction = MissingSchemaAction.AddWithKey

       da.InsertCommand = New MySqlCommand("INSERT INTO mytable (id, name) " & _
                                         "VALUES (@id, @name)", conn)
       da.UpdateCommand = New MySqlCommand("UPDATE mytable SET id=@id, name=@name " & _
                                         "WHERE id=@oldId", conn)
       da.DeleteCommand = New MySqlCommand("DELETE FROM mytable WHERE id=@id", conn)
       da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
       da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")

       da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
       da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")
       da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
       da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
     End Sub

C# example:

     public static void CreateSqlDataAdapter()
     {
       MySqlDataAdapter da = new MySqlDataAdapter("SELECT id, name FROM mytable", "Data Source=localhost;database=test");
       MySqlConnection conn = da.SelectCommand.Connection;
       da.MissingSchemaAction = MissingSchemaAction.AddWithKey;

       da.InsertCommand = new MySqlCommand("INSERT INTO mytable (id, name) " +
                                         "VALUES (@id, @name)", conn);
       da.UpdateCommand = new MySqlCommand("UPDATE mytable SET id=@id, name=@name " +
                                         "WHERE id=@oldId", conn);
       da.DeleteCommand = new MySqlCommand("DELETE FROM mytable WHERE id=@id", conn);
       da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
       da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");

       da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
       da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");
       da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
       da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-deletecommand,  Next: connector-net-examples-mysqldataadapter-insertcommand,  Prev: connector-net-examples-mysqldataadapter-ctor3,  Up: connector-net-examples-mysqldataadapter

20.2.3.52 Property DeleteCommand
................................

Gets or sets an SQL statement or stored procedure used to delete
records from the data set.

*Value:* A `MySqlCommand' used during
`System.Data.Common.DataAdapter.Update' to delete records in the
database that correspond to deleted rows in the `DataSet'.

During `System.Data.Common.DataAdapter.Update', if this property is not
set and primary key information is present in the `DataSet', the
`DeleteCommand' can be generated automatically if you set the
`SelectCommand' property and use the `MySqlCommandBuilder'.  Then, any
additional commands that you do not set are generated by the
`MySqlCommandBuilder'. This generation logic requires key column
information to be present in the `DataSet'.

When `DeleteCommand' is assigned to a previously created
`MySqlCommand', the `MySqlCommand' is not cloned. The `DeleteCommand'
maintains a reference to the previously created `MySqlCommand' object.

*Examples*

The following example creates a `MySqlDataAdapter' and sets the
`SelectCommand' and `DeleteCommand' properties. It assumes you have
already created a `MySqlConnection' object.

Visual Basic example:

     Public Shared Function CreateCustomerAdapter(conn As MySqlConnection) As MySqlDataAdapter
       Dim da As MySqlDataAdapter = New MySqlDataAdapter()
       Dim cmd As MySqlCommand
       Dim parm As MySqlParameter
       ' Create the SelectCommand.
       cmd = New MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn)
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15)
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15)
       da.SelectCommand = cmd
       ' Create the DeleteCommand.
       cmd = New MySqlCommand("DELETE FROM mytable WHERE id=@id", conn)
       parm = cmd.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
       parm.SourceVersion = DataRowVersion.Original
       da.DeleteCommand = cmd
       Return da
     End Function

C# example:

     public static MySqlDataAdapter CreateCustomerAdapter(MySqlConnection conn)
     {
       MySqlDataAdapter da = new MySqlDataAdapter();
       MySqlCommand cmd;
       MySqlParameter parm;
       // Create the SelectCommand.
       cmd = new MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15);
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15);
       da.SelectCommand = cmd;
       // Create the DeleteCommand.
       cmd = new MySqlCommand("DELETE FROM mytable WHERE id=@id", conn);
       parm = cmd.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
       parm.SourceVersion = DataRowVersion.Original;
       da.DeleteCommand = cmd;
       return da;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-insertcommand,  Next: connector-net-examples-mysqldataadapter-updatecommand,  Prev: connector-net-examples-mysqldataadapter-deletecommand,  Up: connector-net-examples-mysqldataadapter

20.2.3.53 Property InsertCommand
................................

Gets or sets an SQL statement or stored procedure used to insert
records into the data set.

*Value:* A `MySqlCommand' used during
`System.Data.Common.DataAdapter.Update' to insert records into the
database that correspond to new rows in the `DataSet'.

During `System.Data.Common.DataAdapter.Update', if this property is not
set and primary key information is present in the `DataSet', the
`InsertCommand' can be generated automatically if you set the
`SelectCommand' property and use the `MySqlCommandBuilder'.  Then, any
additional commands that you do not set are generated by the
`MySqlCommandBuilder'. This generation logic requires key column
information to be present in the `DataSet'.

When `InsertCommand' is assigned to a previously created
`MySqlCommand', the `MySqlCommand' is not cloned. The `InsertCommand'
maintains a reference to the previously created `MySqlCommand' object.

*Note*:

If execution of this command returns rows, these rows may be added to
the `DataSet' depending on how you set the
`MySqlCommand.UpdatedRowSource' property of the `MySqlCommand' object.

*Examples*

The following example creates a `MySqlDataAdapter' and sets the
`SelectCommand' and `InsertCommand' properties. It assumes you have
already created a `MySqlConnection' object.

Visual Basic example:

     Public Shared Function CreateCustomerAdapter(conn As MySqlConnection) As MySqlDataAdapter
       Dim da As MySqlDataAdapter = New MySqlDataAdapter()
       Dim cmd As MySqlCommand
       Dim parm As MySqlParameter
       ' Create the SelectCommand.
       cmd = New MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn)
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15)
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15)
       da.SelectCommand = cmd
       ' Create the InsertCommand.
       cmd = New MySqlCommand("INSERT INTO mytable (id,name) VALUES (@id, @name)", conn)
       cmd.Parameters.Add( "@id", MySqlDbType.VarChar, 15, "id" )
       cmd.Parameters.Add( "@name", MySqlDbType.VarChar, 15, "name" )
       da.InsertCommand = cmd

       Return da
     End Function

C# example:

     public static MySqlDataAdapter CreateCustomerAdapter(MySqlConnection conn)
     {
       MySqlDataAdapter da = new MySqlDataAdapter();
       MySqlCommand cmd;
       MySqlParameter parm;
       // Create the SelectCommand.
       cmd = new MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15);
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15);
       da.SelectCommand = cmd;
       // Create the InsertCommand.
       cmd = new MySqlCommand("INSERT INTO mytable (id,name) VALUES (@id,@name)", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15, "id" );
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15, "name" );

       da.InsertCommand = cmd;
       return da;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-updatecommand,  Next: connector-net-examples-mysqldataadapter-selectcommand,  Prev: connector-net-examples-mysqldataadapter-insertcommand,  Up: connector-net-examples-mysqldataadapter

20.2.3.54 Property UpdateCommand
................................

Gets or sets an SQL statement or stored procedure used to updated
records in the data source.

*Value:* A `MySqlCommand' used during
`System.Data.Common.DataAdapter.Update' to update records in the
database with data from the `DataSet'.

During `System.Data.Common.DataAdapter.Update', if this property is not
set and primary key information is present in the `DataSet', the
`UpdateCommand' can be generated automatically if you set the
`SelectCommand' property and use the `MySqlCommandBuilder'.  Then, any
additional commands that you do not set are generated by the
`MySqlCommandBuilder'. This generation logic requires key column
information to be present in the `DataSet'.

When `UpdateCommand' is assigned to a previously created
`MySqlCommand', the `MySqlCommand' is not cloned. The `UpdateCommand'
maintains a reference to the previously created `MySqlCommand' object.

*Note*:

If execution of this command returns rows, these rows may be merged
with the DataSet depending on how you set the
`MySqlCommand.UpdatedRowSource' property of the `MySqlCommand' object.

*Examples*

The following example creates a `MySqlDataAdapter' and sets the
`SelectCommand' and `UpdateCommand' properties. It assumes you have
already created a `MySqlConnection' object.

Visual Basic example:

     Public Shared Function CreateCustomerAdapter(conn As MySqlConnection) As MySqlDataAdapter
       Dim da As MySqlDataAdapter = New MySqlDataAdapter()
       Dim cmd As MySqlCommand
       Dim parm As MySqlParameter
       ' Create the SelectCommand.
       cmd = New MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn)
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15)
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15)
       da.SelectCommand = cmd
       ' Create the UpdateCommand.
       cmd = New MySqlCommand("UPDATE mytable SET id=@id, name=@name WHERE id=@oldId", conn)
       cmd.Parameters.Add( "@id", MySqlDbType.VarChar, 15, "id" )
       cmd.Parameters.Add( "@name", MySqlDbType.VarChar, 15, "name" )

       parm = cmd.Parameters.Add("@oldId", MySqlDbType.VarChar, 15, "id")
       parm.SourceVersion = DataRowVersion.Original

       da.UpdateCommand = cmd

       Return da
     End Function

C# example:

     public static MySqlDataAdapter CreateCustomerAdapter(MySqlConnection conn)
     {
       MySqlDataAdapter da = new MySqlDataAdapter();
       MySqlCommand cmd;
       MySqlParameter parm;
       // Create the SelectCommand.
       cmd = new MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15);
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15);
       da.SelectCommand = cmd;
       // Create the UpdateCommand.
       cmd = new MySqlCommand("UPDATE mytable SET id=@id, name=@name WHERE id=@oldId", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15, "id" );
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15, "name" );

       parm = cmd.Parameters.Add( "@oldId", MySqlDbType.VarChar, 15, "id" );
       parm.SourceVersion = DataRowVersion.Original;

       da.UpdateCommand = cmd;
       return da;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-selectcommand,  Prev: connector-net-examples-mysqldataadapter-updatecommand,  Up: connector-net-examples-mysqldataadapter

20.2.3.55 Property SelectCommand
................................

Gets or sets an SQL statement or stored procedure used to select
records in the data source.

*Value:* A `MySqlCommand' used during
`System.Data.Common.DbDataAdapter.Fill' to select records from the
database for placement in the `DataSet'.

When `SelectCommand' is assigned to a previously created
`MySqlCommand', the `MySqlCommand' is not cloned. The `SelectCommand'
maintains a reference to the previously created `MySqlCommand' object.

If the `SelectCommand' does not return any rows, no tables are added to
the `DataSet', and no exception is raised.

*Examples*

The following example creates a `MySqlDataAdapter' and sets the
`SelectCommand' and `InsertCommand' properties. It assumes you have
already created a `MySqlConnection' object.

Visual Basic example:

     Public Shared Function CreateCustomerAdapter(conn As MySqlConnection) As MySqlDataAdapter
       Dim da As MySqlDataAdapter = New MySqlDataAdapter()
       Dim cmd As MySqlCommand
       Dim parm As MySqlParameter
       ' Create the SelectCommand.
       cmd = New MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn)
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15)
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15)
       da.SelectCommand = cmd
       ' Create the InsertCommand.
       cmd = New MySqlCommand("INSERT INTO mytable (id,name) VALUES (@id, @name)", conn)
       cmd.Parameters.Add( "@id", MySqlDbType.VarChar, 15, "id" )
       cmd.Parameters.Add( "@name", MySqlDbType.VarChar, 15, "name" )
       da.InsertCommand = cmd

       Return da
     End Function

C# example:

     public static MySqlDataAdapter CreateCustomerAdapter(MySqlConnection conn)
     {
       MySqlDataAdapter da = new MySqlDataAdapter();
       MySqlCommand cmd;
       MySqlParameter parm;
       // Create the SelectCommand.
       cmd = new MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15);
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15);
       da.SelectCommand = cmd;
       // Create the InsertCommand.
       cmd = new MySqlCommand("INSERT INTO mytable (id,name) VALUES (@id,@name)", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15, "id" );
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15, "name" );

       da.InsertCommand = cmd;
       return da;
     }


File: manual.info,  Node: connector-net-examples-mysqldatareader,  Next: connector-net-examples-mysqlexception,  Prev: connector-net-examples-mysqldataadapter,  Up: connector-net-examples

20.2.3.56 Using MySqlDataReader
...............................

* Menu:

* connector-net-examples-mysqldatareader-getbytes::  Method GetBytes
* connector-net-examples-mysqldatareader-gettimespan::  Method GetTimeSpan
* connector-net-examples-mysqldatareader-getdatetime::  Method GetDateTime
* connector-net-examples-mysqldatareader-getmysqldatetime::  Method GetMySqlDateTime
* connector-net-examples-mysqldatareader-getstring::  Method GetString
* connector-net-examples-mysqldatareader-getdecimal::  Method GetDecimal
* connector-net-examples-mysqldatareader-getdouble::  Method GetDouble
* connector-net-examples-mysqldatareader-getfloat::  Method GetFloat
* connector-net-examples-mysqldatareader-getgiud::  Method GetGuid
* connector-net-examples-mysqldatareader-getint16::  Method GetInt16
* connector-net-examples-mysqldatareader-getint32::  Method GetInt32
* connector-net-examples-mysqldatareader-getint64::  Method GetInt64
* connector-net-examples-mysqldatareader-getuint16::  Method GetUInt16
* connector-net-examples-mysqldatareader-getuint32::  Method GetUInt32
* connector-net-examples-mysqldatareader-getuint64::  Method GetUInt64

To create a `MySQLDataReader', you must call the
`MySqlCommand.ExecuteReader' method of the `MySqlCommand' object,
rather than directly using a constructor.

While the `MySqlDataReader' is in use, the associated `MySqlConnection'
is busy serving the `MySqlDataReader', and no other operations can be
performed on the `MySqlConnection' other than closing it. This is the
case until the `MySqlDataReader.Close' method of the `MySqlDataReader'
is called.

`MySqlDataReader.IsClosed' and `MySqlDataReader.RecordsAffected' are
the only properties that you can call after the `MySqlDataReader' is
closed. Though the `RecordsAffected' property may be accessed at any
time while the `MySqlDataReader' exists, always call `Close' before
returning the value of `RecordsAffected' to ensure an accurate return
value.

For optimal performance, `MySqlDataReader' avoids creating unnecessary
objects or making unnecessary copies of data. As a result, multiple
calls to methods such as `MySqlDataReader.GetValue' return a reference
to the same object. Use caution if you are modifying the underlying
value of the objects returned by methods such as `GetValue'.

*Examples*

The following example creates a `MySqlConnection', a `MySqlCommand',
and a `MySqlDataReader'. The example reads through the data, writing it
out to the console. Finally, the example closes the `MySqlDataReader',
then the `MySqlConnection'.

Visual Basic example:

     Public Sub ReadMyData(myConnString As String)
       Dim mySelectQuery As String = "SELECT OrderID, CustomerID FROM Orders"
       Dim myConnection As New MySqlConnection(myConnString)
       Dim myCommand As New MySqlCommand(mySelectQuery, myConnection)
       myConnection.Open()
       Dim myReader As MySqlDataReader
       myReader = myCommand.ExecuteReader()
       ' Always call Read before accessing data.
       While myReader.Read()
         Console.WriteLine((myReader.GetInt32(0) & ", " & myReader.GetString(1)))
       End While
       ' always call Close when done reading.
       myReader.Close()
       ' Close the connection when done with it.
       myConnection.Close()
     End Sub 'ReadMyData

C# example:

     public void ReadMyData(string myConnString) {
       string mySelectQuery = "SELECT OrderID, CustomerID FROM Orders";
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       MySqlCommand myCommand = new MySqlCommand(mySelectQuery,myConnection);
       myConnection.Open();
       MySqlDataReader myReader;
       myReader = myCommand.ExecuteReader();
       // Always call Read before accessing data.
       while (myReader.Read()) {
         Console.WriteLine(myReader.GetInt32(0) + ", " + myReader.GetString(1));
       }
       // always call Close when done reading.
       myReader.Close();
       // Close the connection when done with it.
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqldatareader-getbytes,  Next: connector-net-examples-mysqldatareader-gettimespan,  Prev: connector-net-examples-mysqldatareader,  Up: connector-net-examples-mysqldatareader

20.2.3.57 Method GetBytes
.........................

`GetBytes' returns the number of available bytes in the field. In most
cases this is the exact length of the field. However, the number
returned may be less than the true length of the field if `GetBytes' has
already been used to obtain bytes from the field. This may be the case,
for example, if the `MySqlDataReader' is reading a large data structure
into a buffer. For more information, see the `SequentialAccess' setting
for `MySqlCommand.CommandBehavior'.

If you pass a buffer that is a null reference (`Nothing' in Visual
Basic), `GetBytes' returns the length of the field in bytes.

No conversions are performed; therefore the data retrieved must already
be a byte array.


File: manual.info,  Node: connector-net-examples-mysqldatareader-gettimespan,  Next: connector-net-examples-mysqldatareader-getdatetime,  Prev: connector-net-examples-mysqldatareader-getbytes,  Up: connector-net-examples-mysqldatareader

20.2.3.58 Method GetTimeSpan
............................

Gets the value of the specified column as a `TimeSpan' object.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getdatetime,  Next: connector-net-examples-mysqldatareader-getmysqldatetime,  Prev: connector-net-examples-mysqldatareader-gettimespan,  Up: connector-net-examples-mysqldatareader

20.2.3.59 Method GetDateTime
............................

Gets the value of the specified column as a `System.DateTime' object.

*Note*:

MySQL allows date columns to contain the value '0000-00-00' and
datetime columns to contain the value '0000-00-00 00:00:00'. The
DateTime structure cannot contain or represent these values. To read a
datetime value from a column that might contain zero values, use
`GetMySqlDateTime'. The behavior of reading a zero datetime column
using this method is defined by the `ZeroDateTimeBehavior' connection
string option. For more information on this option, please refer to
`MySqlConnection.ConnectionString'.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getmysqldatetime,  Next: connector-net-examples-mysqldatareader-getstring,  Prev: connector-net-examples-mysqldatareader-getdatetime,  Up: connector-net-examples-mysqldatareader

20.2.3.60 Method GetMySqlDateTime
.................................

Gets the value of the specified column as a
`MySql.Data.Types.MySqlDateTime' object.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getstring,  Next: connector-net-examples-mysqldatareader-getdecimal,  Prev: connector-net-examples-mysqldatareader-getmysqldatetime,  Up: connector-net-examples-mysqldatareader

20.2.3.61 Method GetString
..........................

Gets the value of the specified column as a `String' object.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getdecimal,  Next: connector-net-examples-mysqldatareader-getdouble,  Prev: connector-net-examples-mysqldatareader-getstring,  Up: connector-net-examples-mysqldatareader

20.2.3.62 Method GetDecimal
...........................

Gets the value of the specified column as a `Decimal' object.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getdouble,  Next: connector-net-examples-mysqldatareader-getfloat,  Prev: connector-net-examples-mysqldatareader-getdecimal,  Up: connector-net-examples-mysqldatareader

20.2.3.63 Method GetDouble
..........................

Gets the value of the specified column as a double-precision floating
point number.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getfloat,  Next: connector-net-examples-mysqldatareader-getgiud,  Prev: connector-net-examples-mysqldatareader-getdouble,  Up: connector-net-examples-mysqldatareader

20.2.3.64 Method GetFloat
.........................

Gets the value of the specified column as a single-precision floating
point number.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getgiud,  Next: connector-net-examples-mysqldatareader-getint16,  Prev: connector-net-examples-mysqldatareader-getfloat,  Up: connector-net-examples-mysqldatareader

20.2.3.65 Method GetGuid
........................

Gets the value of the specified column as a globally-unique identifier
(GUID).

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getint16,  Next: connector-net-examples-mysqldatareader-getint32,  Prev: connector-net-examples-mysqldatareader-getgiud,  Up: connector-net-examples-mysqldatareader

20.2.3.66 Method GetInt16
.........................

Gets the value of the specified column as a 16-bit signed integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getint32,  Next: connector-net-examples-mysqldatareader-getint64,  Prev: connector-net-examples-mysqldatareader-getint16,  Up: connector-net-examples-mysqldatareader

20.2.3.67 Method GetInt32
.........................

Gets the value of the specified column as a 32-bit signed integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getint64,  Next: connector-net-examples-mysqldatareader-getuint16,  Prev: connector-net-examples-mysqldatareader-getint32,  Up: connector-net-examples-mysqldatareader

20.2.3.68 Method GetInt64
.........................

Gets the value of the specified column as a 64-bit signed integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getuint16,  Next: connector-net-examples-mysqldatareader-getuint32,  Prev: connector-net-examples-mysqldatareader-getint64,  Up: connector-net-examples-mysqldatareader

20.2.3.69 Method GetUInt16
..........................

Gets the value of the specified column as a 16-bit unsigned integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getuint32,  Next: connector-net-examples-mysqldatareader-getuint64,  Prev: connector-net-examples-mysqldatareader-getuint16,  Up: connector-net-examples-mysqldatareader

20.2.3.70 Method GetUInt32
..........................

Gets the value of the specified column as a 32-bit unsigned integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getuint64,  Prev: connector-net-examples-mysqldatareader-getuint32,  Up: connector-net-examples-mysqldatareader

20.2.3.71 Method GetUInt64
..........................

Gets the value of the specified column as a 64-bit unsigned integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqlexception,  Next: connector-net-examples-mysqlparameter,  Prev: connector-net-examples-mysqldatareader,  Up: connector-net-examples

20.2.3.72 Using MySqlException
..............................

This class is created whenever the MySQL Data Provider encounters an
error generated from the server.

Any open connections are not automatically closed when an exception is
thrown. If the client application determines that the exception is
fatal, it should close any open `MySqlDataReader' objects or
`MySqlConnection' objects.

*Examples*

The following example generates a `MySqlException' due to a missing
server, and then displays the exception.

Visual Basic example:

     Public Sub ShowException()
       Dim mySelectQuery As String = "SELECT column1 FROM table1"
       Dim myConnection As New MySqlConnection ("Data Source=localhost;Database=Sample;")
       Dim myCommand As New MySqlCommand(mySelectQuery, myConnection)
       Try
         myCommand.Connection.Open()
       Catch e As MySqlException
         MessageBox.Show( e.Message )
       End Try
     End Sub

C# example:

     public void ShowException()
     {
       string mySelectQuery = "SELECT column1 FROM table1";
       MySqlConnection myConnection =
           new MySqlConnection("Data Source=localhost;Database=Sample;");
       MySqlCommand myCommand = new MySqlCommand(mySelectQuery,myConnection);
       try
       {
         myCommand.Connection.Open();
       }
       catch (MySqlException e)
       {
         MessageBox.Show( e.Message );
       }
     }


File: manual.info,  Node: connector-net-examples-mysqlparameter,  Next: connector-net-examples-mysqlparametercollection,  Prev: connector-net-examples-mysqlexception,  Up: connector-net-examples

20.2.3.73 Using MySqlParameter
..............................

Parameter names are not case sensitive.

*Examples*

The following example creates multiple instances of `MySqlParameter'
through the `MySqlParameterCollection' collection within the
`MySqlDataAdapter'. These parameters are used to select data from the
data source and place the data in the `DataSet'. This example assumes
that a `DataSet' and a `MySqlDataAdapter' have already been created
with the appropriate schema, commands, and connection.

Visual Basic example:

     Public Sub AddSqlParameters()
       ' ...
       ' create myDataSet and myDataAdapter
       ' ...
       myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", MySqlDbType.VarChar, 80).Value = "toasters"
       myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", MySqlDbType.Long).Value = 239

       myDataAdapter.Fill(myDataSet)
     End Sub 'AddSqlParameters

C# example:

     public void AddSqlParameters()
     {
       // ...
       // create myDataSet and myDataAdapter
       // ...
       myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", MySqlDbType.VarChar, 80).Value = "toasters";
       myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", MySqlDbType.Long).Value = 239;
       myDataAdapter.Fill(myDataSet);
     }


File: manual.info,  Node: connector-net-examples-mysqlparametercollection,  Next: connector-net-examples-mysqltransaction,  Prev: connector-net-examples-mysqlparameter,  Up: connector-net-examples

20.2.3.74 Using MySqlParameterCollection
........................................

The number of the parameters in the collection must be equal to the
number of parameter placeholders within the command text, or an
exception will be generated.

*Examples*

The following example creates multiple instances of `MySqlParameter'
through the `MySqlParameterCollection' collection within the
`MySqlDataAdapter'. These parameters are used to select data within the
data source and place the data in the `DataSet'. This code assumes that
a `DataSet' and a `MySqlDataAdapter' have already been created with the
appropriate schema, commands, and connection.

Visual Basic example:

     Public Sub AddParameters()
       ' ...
       ' create myDataSet and myDataAdapter
       ' ...
       myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", MySqlDbType.VarChar, 80).Value = "toasters"
       myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", MySqlDbType.Long).Value = 239

       myDataAdapter.Fill(myDataSet)
     End Sub 'AddSqlParameters

C# example:

     public void AddSqlParameters()
     {
       // ...
       // create myDataSet and myDataAdapter
       // ...
       myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", MySqlDbType.VarChar, 80).Value = "toasters";
       myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", MySqlDbType.Long).Value = 239;
       myDataAdapter.Fill(myDataSet);
     }


File: manual.info,  Node: connector-net-examples-mysqltransaction,  Prev: connector-net-examples-mysqlparametercollection,  Up: connector-net-examples

20.2.3.75 Using MySqlTransaction
................................

* Menu:

* connector-net-examples-mysqltransaction-rollback::  Method Rollback
* connector-net-examples-mysqltransaction-commit::  Method Commit

Represents an SQL transaction to be made in a MySQL database.  This
class cannot be inherited.

The application creates a `MySqlTransaction' object by calling
`MySqlConnection.BeginTransaction' on the `MySqlConnection' object. All
subsequent operations associated with the transaction (for example,
committing or aborting the transaction), are performed on the
`MySqlTransaction' object.

*Note*:

Once you have started a transaction on a connection all subsequent
commands on that connection are applied within the scope of the
transaction. You cannot execute an SQL statement on the same connection
outside of the transaction scope. If you need to do this while
executing statements that are part of a transaction, open a second a
connection to be used for execution the non-transaction statements.

*Examples*

The following example creates a `MySqlConnection' and a
`MySqlTransaction'. It also demonstrates how to use the
`MySqlConnection.BeginTransaction', `MySqlTransaction.Commit', and
`MySqlTransaction.Rollback' methods.

Visual Basic example:

     Public Sub RunTransaction(myConnString As String)
       Dim myConnection As New MySqlConnection(myConnString)
       myConnection.Open()

       Dim myCommand As MySqlCommand = myConnection.CreateCommand()
       Dim myTrans As MySqlTransaction

       ' Start a local transaction
       myTrans = myConnection.BeginTransaction()
       ' Must assign both transaction object and connection
       ' to Command object for a pending local transaction
       myCommand.Connection = myConnection
       myCommand.Transaction = myTrans

       Try
         myCommand.CommandText = "Insert into Region (RegionID, RegionDescription) VALUES (100, 'Description')"
         myCommand.ExecuteNonQuery()
         myCommand.CommandText = "Insert into Region (RegionID, RegionDescription) VALUES (101, 'Description')"
         myCommand.ExecuteNonQuery()
         myTrans.Commit()
         Console.WriteLine("Both records are written to database.")
       Catch e As Exception
         Try
           myTrans.Rollback()
         Catch ex As MySqlException
           If Not myTrans.Connection Is Nothing Then
             Console.WriteLine("An exception of type " & ex.GetType().ToString() & _
                          " was encountered while attempting to roll back the transaction.")
           End If
         End Try

         Console.WriteLine("An exception of type " & e.GetType().ToString() & _
                           "was encountered while inserting the data.")
         Console.WriteLine("Neither record was written to database.")
       Finally
         myConnection.Close()
       End Try
     End Sub 'RunTransaction

C# example:

     public void RunTransaction(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MySqlCommand myCommand = myConnection.CreateCommand();
       MySqlTransaction myTrans;
       // Start a local transaction
       myTrans = myConnection.BeginTransaction();
       // Must assign both transaction object and connection
       // to Command object for a pending local transaction
       myCommand.Connection = myConnection;
       myCommand.Transaction = myTrans;
       try
       {
         myCommand.CommandText = "Insert into Region (RegionID, RegionDescription) VALUES (100, 'Description')";
         myCommand.ExecuteNonQuery();
         myCommand.CommandText = "Insert into Region (RegionID, RegionDescription) VALUES (101, 'Description')";
         myCommand.ExecuteNonQuery();
         myTrans.Commit();
         Console.WriteLine("Both records are written to database.");
       }
       catch(Exception e)
       {
         try
         {
           myTrans.Rollback();
         }
         catch (MySqlException ex)
         {
           if (myTrans.Connection != null)
           {
             Console.WriteLine("An exception of type " + ex.GetType() +
                               " was encountered while attempting to roll back the transaction.");
           }
         }

         Console.WriteLine("An exception of type " + e.GetType() +
                           " was encountered while inserting the data.");
         Console.WriteLine("Neither record was written to database.");
       }
       finally
       {
         myConnection.Close();
       }
     }


File: manual.info,  Node: connector-net-examples-mysqltransaction-rollback,  Next: connector-net-examples-mysqltransaction-commit,  Prev: connector-net-examples-mysqltransaction,  Up: connector-net-examples-mysqltransaction

20.2.3.76 Method Rollback
.........................

Rolls back a transaction from a pending state.

The Rollback method is equivalent to the MySQL statement ROLLBACK. The
transaction can only be rolled back from a pending state (after
BeginTransaction has been called, but before Commit is called).

*Examples*

The following example creates `MySqlConnection' and a
`MySqlTransaction'. It also demonstrates how to use the
`MySqlConnection.BeginTransaction', `Commit', and `Rollback' methods.

Visual Basic example:

     Public Sub RunSqlTransaction(myConnString As String)
       Dim myConnection As New MySqlConnection(myConnString)
       myConnection.Open()

       Dim myCommand As MySqlCommand = myConnection.CreateCommand()
       Dim myTrans As MySqlTransaction

       ' Start a local transaction
       myTrans = myConnection.BeginTransaction()

       ' Must assign both transaction object and connection
       ' to Command object for a pending local transaction
       myCommand.Connection = myConnection
       myCommand.Transaction = myTrans

       Try
         myCommand.CommandText = "Insert into mytable (id, desc) VALUES (100, 'Description')"
         myCommand.ExecuteNonQuery()
         myCommand.CommandText = "Insert into mytable (id, desc) VALUES (101, 'Description')"
         myCommand.ExecuteNonQuery()
         myTrans.Commit()
         Console.WriteLine("Success.")
       Catch e As Exception
         Try
           myTrans.Rollback()
         Catch ex As MySqlException
           If Not myTrans.Connection Is Nothing Then
             Console.WriteLine("An exception of type " & ex.GetType().ToString() & _
                               " was encountered while attempting to roll back the transaction.")
           End If
         End Try

         Console.WriteLine("An exception of type " & e.GetType().ToString() & _
                           "was encountered while inserting the data.")
         Console.WriteLine("Neither record was written to database.")
       Finally
         myConnection.Close()
       End Try
     End Sub

C# example:

     public void RunSqlTransaction(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MySqlCommand myCommand = myConnection.CreateCommand();
       MySqlTransaction myTrans;
       // Start a local transaction
       myTrans = myConnection.BeginTransaction();
       // Must assign both transaction object and connection
       // to Command object for a pending local transaction
       myCommand.Connection = myConnection;
       myCommand.Transaction = myTrans;
       try
       {
         myCommand.CommandText = "Insert into mytable (id, desc) VALUES (100, 'Description')";
         myCommand.ExecuteNonQuery();
         myCommand.CommandText = "Insert into mytable (id, desc) VALUES (101, 'Description')";
         myCommand.ExecuteNonQuery();
         myTrans.Commit();
         Console.WriteLine("Both records are written to database.");
       }
       catch(Exception e)
       {
         try
         {
           myTrans.Rollback();
         }
         catch (MySqlException ex)
         {
           if (myTrans.Connection != null)
           {
             Console.WriteLine("An exception of type " + ex.GetType() +
                               " was encountered while attempting to roll back the transaction.");
           }
         }

         Console.WriteLine("An exception of type " + e.GetType() +
                           " was encountered while inserting the data.");
         Console.WriteLine("Neither record was written to database.");
       }
       finally
       {
         myConnection.Close();
       }
     }


File: manual.info,  Node: connector-net-examples-mysqltransaction-commit,  Prev: connector-net-examples-mysqltransaction-rollback,  Up: connector-net-examples-mysqltransaction

20.2.3.77 Method Commit
.......................

Commits the database transaction.

The `Commit' method is equivalent to the MySQL SQL statement COMMIT.

*Examples*

The following example creates `MySqlConnection' and a
`MySqlTransaction'. It also demonstrates how to use the
`MySqlConnection.BeginTransaction', `Commit', and `Rollback' methods.

Visual Basic example:

     Public Sub RunSqlTransaction(myConnString As String)
       Dim myConnection As New MySqlConnection(myConnString)
       myConnection.Open()

       Dim myCommand As MySqlCommand = myConnection.CreateCommand()
       Dim myTrans As MySqlTransaction

       ' Start a local transaction
       myTrans = myConnection.BeginTransaction()

       ' Must assign both transaction object and connection
       ' to Command object for a pending local transaction
       myCommand.Connection = myConnection
       myCommand.Transaction = myTrans

       Try
         myCommand.CommandText = "Insert into mytable (id, desc) VALUES (100, 'Description')"
         myCommand.ExecuteNonQuery()
         myCommand.CommandText = "Insert into mytable (id, desc) VALUES (101, 'Description')"
         myCommand.ExecuteNonQuery()
         myTrans.Commit()
         Console.WriteLine("Success.")
       Catch e As Exception
         Try
           myTrans.Rollback()
         Catch ex As MySqlException
           If Not myTrans.Connection Is Nothing Then
             Console.WriteLine("An exception of type " & ex.GetType().ToString() & _
                               " was encountered while attempting to roll back the transaction.")
           End If
         End Try

         Console.WriteLine("An exception of type " & e.GetType().ToString() & _
                           "was encountered while inserting the data.")
         Console.WriteLine("Neither record was written to database.")
       Finally
         myConnection.Close()
       End Try
     End Sub

C# example:

     public void RunSqlTransaction(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MySqlCommand myCommand = myConnection.CreateCommand();
       MySqlTransaction myTrans;
       // Start a local transaction
       myTrans = myConnection.BeginTransaction();
       // Must assign both transaction object and connection
       // to Command object for a pending local transaction
       myCommand.Connection = myConnection;
       myCommand.Transaction = myTrans;
       try
       {
         myCommand.CommandText = "Insert into mytable (id, desc) VALUES (100, 'Description')";
         myCommand.ExecuteNonQuery();
         myCommand.CommandText = "Insert into mytable (id, desc) VALUES (101, 'Description')";
         myCommand.ExecuteNonQuery();
         myTrans.Commit();
         Console.WriteLine("Both records are written to database.");
       }
       catch(Exception e)
       {
         try
         {
           myTrans.Rollback();
         }
         catch (MySqlException ex)
         {
           if (myTrans.Connection != null)
           {
             Console.WriteLine("An exception of type " + ex.GetType() +
                               " was encountered while attempting to roll back the transaction.");
           }
         }

         Console.WriteLine("An exception of type " + e.GetType() +
                           " was encountered while inserting the data.");
         Console.WriteLine("Neither record was written to database.");
       }
       finally
       {
         myConnection.Close();
       }
     }


File: manual.info,  Node: connector-net-ref,  Next: connector-net-using,  Prev: connector-net-examples,  Up: connector-net

20.2.4 Connector/NET Reference
------------------------------

* Menu:

* connector-net-ref-mysqlclient::  `MySql.Data.MySqlClient'
* connector-net-ref-types::      `MySql.Data.Types'

This section of the manual contains a complete reference to the
Connector/NET ADO.NET component, automatically generated from the
embedded documentation.


File: manual.info,  Node: connector-net-ref-mysqlclient,  Next: connector-net-ref-types,  Prev: connector-net-ref,  Up: connector-net-ref

20.2.4.1 `MySql.Data.MySqlClient'
.................................

* Menu:

* connector-net-ref-mysqlclienthierarchy::  `MySql.Data.MySqlClientHierarchy'
* connector-net-ref-mysqlclient-mysqlcommand::  `MySqlCommand' Class
* connector-net-ref-mysqlclient-mysqlcommandbuilder::  `MySqlCommandBuilder' Class
* connector-net-ref-mysqlclient-mysqlexception::  `MySqlException' Class
* connector-net-ref-mysqlclient-mysqlhelper::  `MySqlHelper' Class
* connector-net-ref-mysqlclient-mysqlerrorcode::  `MySqlErrorCode' Enumeration

*Note Namespace hierarchy: connector-net-ref-mysqlclienthierarchy.

*Classes*

*Class*                              *Description*
*Note MySqlCommand:                  
connector-net-ref-mysqlclient-mysqlcommand.
*Note MySqlCommandBuilder:           
connector-net-ref-mysqlclient-mysqlcommandbuilder.
*Note MySqlConnection:               
connector-net-ref-mysqlclient-mysqlconnection.
*Note MySqlDataAdapter:              
connector-net-ref-mysqlclient-mysqldataadapter.
*Note MySqlDataReader:               Provides a means of reading a
connector-net-ref-mysqlclient-mysqldatareader.forward-only stream of rows from a
                                     MySQL database. This class cannot
                                     be inherited.
*Note MySqlError:                    Collection of error codes that can
connector-net-ref-mysqlclient-mysqlerror.be returned by the server
*Note MySqlException:                The exception that is thrown when
connector-net-ref-mysqlclient-mysqlexception.MySQL returns an error. This class
                                     cannot be inherited.
*Note MySqlHelper:                   Helper class that makes it easier
connector-net-ref-mysqlclient-mysqlhelper.to work with the provider.
*Note MySqlInfoMessageEventArgs:     Provides data for the InfoMessage
connector-net-ref-mysqlclient-mysqlinfomessageeventargs.event. This class cannot be
                                     inherited.
*Note MySqlParameter:                Represents a parameter to a *Note
connector-net-ref-mysqlclient-mysqlparameter.MySqlCommand:
                                     connector-net-ref-mysqlclient-mysqlcommand
                                     , and optionally, its mapping to
                                     DataSetcolumns. This class cannot
                                     be inherited.
*Note MySqlParameterCollection:      Represents a collection of
connector-net-ref-mysqlclient-mysqlparametercollection.parameters relevant to a *Note
                                     MySqlCommand:
                                     connector-net-ref-mysqlclient-mysqlcommand.
                                     as well as their respective
                                     mappings to columns in a DataSet.
                                     This class cannot be inherited.
*Note MySqlRowUpdatedEventArgs:      Provides data for the RowUpdated
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs.event. This class cannot be
                                     inherited.
*Note MySqlRowUpdatingEventArgs:     Provides data for the RowUpdating
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs.event. This class cannot be
                                     inherited.
*Note MySqlTransaction:              
connector-net-ref-mysqlclient-mysqltransaction.

*Delegates*

*Delegate*                           *Description*
*Note MySqlInfoMessageEventHandler:  Represents the method that will
connector-net-ref-mysqlclient-mysqlinfomessageeventhandler.handle the *Note InfoMessage:
                                     connector-net-ref-mysqlclient-mysqlconnection-infomessage.
                                     event of a *Note MySqlConnection:
                                     connector-net-ref-mysqlclient-mysqlconnection.
*Note MySqlRowUpdatedEventHandler:   Represents the method that will
connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler.handle the RowUpdatedevent of a
                                     *Note MySqlDataAdapter:
                                     connector-net-ref-mysqlclient-mysqldataadapter
                                     .
*Note MySqlRowUpdatingEventHandler:  Represents the method that will
connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler.handle the RowUpdatingevent of a
                                     *Note MySqlDataAdapter:
                                     connector-net-ref-mysqlclient-mysqldataadapter
                                     .

*Enumerations*

*Enumeration*                        *Description*
*Note MySqlDbType:                   Specifies MySQL specific data type
connector-net-ref-mysqlclient-mysqldbtype.of a field, property, for use in a
                                     *Note MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter
                                     .
*Note MySqlErrorCode:                
connector-net-ref-mysqlclient-mysqlerrorcode.


File: manual.info,  Node: connector-net-ref-mysqlclienthierarchy,  Next: connector-net-ref-mysqlclient-mysqlcommand,  Prev: connector-net-ref-mysqlclient,  Up: connector-net-ref-mysqlclient

20.2.4.2 `MySql.Data.MySqlClientHierarchy'
..........................................

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder,  Prev: connector-net-ref-mysqlclienthierarchy,  Up: connector-net-ref-mysqlclient

20.2.4.3 `MySqlCommand' Class
.............................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandmembers::  `MySqlCommand' Members

For a list of all members of this type, see *Note MySqlCommand Members:
connector-net-ref-mysqlclient-mysqlcommandmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlCommand_
       Inherits Component_
       Implements IDbCommand, ICloneable

*Syntax: C#*

     public sealed class MySqlCommand : Component, IDbCommand, ICloneable

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlCommand Members:
connector-net-ref-mysqlclient-mysqlcommandmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandmembers,  Prev: connector-net-ref-mysqlclient-mysqlcommand,  Up: connector-net-ref-mysqlclient-mysqlcommand

20.2.4.4 `MySqlCommand' Members
...............................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandconstructor::  `MySqlCommand' Constructor
* connector-net-ref-mysqlclient-mysqlcommand-commandtext::  CommandText Property
* connector-net-ref-mysqlclient-mysqlcommand-commandtimeout::  CommandTimeout Property
* connector-net-ref-mysqlclient-mysqlcommand-commandtype::  CommandType Property
* connector-net-ref-mysqlclient-mysqlcommand-connection::  Connection Property
* connector-net-ref-mysqlclient-mysqlcommand-isprepared::  IsPrepared Property
* connector-net-ref-mysqlclient-mysqlcommand-parameters::  Parameters Property
* connector-net-ref-mysqlclient-mysqlcommand-transaction::  Transaction Property
* connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource::  UpdatedRowSource Property
* connector-net-ref-mysqlclient-mysqlcommand-cancel::  `MySqlCommand.Cancel' Method
* connector-net-ref-mysqlclient-mysqlcommand-createparameter::  `MySqlCommand.CreateParameter' Method
* connector-net-ref-mysqlclient-mysqlcommand-executenonquery::  `MySqlCommand.ExecuteNonQuery' Method
* connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads::  ExecuteReader Method
* connector-net-ref-mysqlclient-mysqlcommand-executescalar::  `MySqlCommand.ExecuteScalar' Method
* connector-net-ref-mysqlclient-mysqlcommand-prepare::  `MySqlCommand.Prepare' Method

*Note MySqlCommand overview: connector-net-ref-mysqlclient-mysqlcommand.

*Public Instance Constructors*

*Note MySqlCommand:                  Overloaded. Initializes a new
connector-net-ref-mysqlclient-mysqlcommandconstructor.instance of the MySqlCommand class.

*Public Instance Properties*

*Note CommandText:                   
connector-net-ref-mysqlclient-mysqlcommand-commandtext.
*Note CommandTimeout:                
connector-net-ref-mysqlclient-mysqlcommand-commandtimeout.
*Note CommandType:                   
connector-net-ref-mysqlclient-mysqlcommand-commandtype.
*Note Connection:                    
connector-net-ref-mysqlclient-mysqlcommand-connection.
Container(inherited from Component)  Gets the IContainerthat contains
                                     the Component.
*Note IsPrepared:                    
connector-net-ref-mysqlclient-mysqlcommand-isprepared.
*Note Parameters:                    
connector-net-ref-mysqlclient-mysqlcommand-parameters.
Site(inherited from Component)       Gets or sets the ISiteof the
                                     Component.
*Note Transaction:                   
connector-net-ref-mysqlclient-mysqlcommand-transaction.
*Note UpdatedRowSource:              
connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource.

*Public Instance Methods*

*Note Cancel:                        Attempts to cancel the execution of
connector-net-ref-mysqlclient-mysqlcommand-cancel.a MySqlCommand. This operation is
                                     not supported.
CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
*Note CreateParameter:               Creates a new instance of a *Note
connector-net-ref-mysqlclient-mysqlcommand-createparameter.MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     object.
Dispose(inherited from Component)    Releases all resources used by the
                                     Component.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
*Note ExecuteNonQuery:               
connector-net-ref-mysqlclient-mysqlcommand-executenonquery.
*Note ExecuteReader:                 Overloaded.
connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads.
*Note ExecuteScalar:                 
connector-net-ref-mysqlclient-mysqlcommand-executescalar.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note Prepare:                       
connector-net-ref-mysqlclient-mysqlcommand-prepare.
ToString(inherited from Component)   Returns a Stringcontaining the name
                                     of the Component, if any. This
                                     method should not be overridden.

*Public Instance Events*

Disposed(inherited from Component)   Adds an event handler to listen to
                                     the Disposedevent on the component.

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandconstructor,  Next: connector-net-ref-mysqlclient-mysqlcommand-commandtext,  Prev: connector-net-ref-mysqlclient-mysqlcommandmembers,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.5 `MySqlCommand' Constructor
...................................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandconstructor1::  `MySqlCommand' Constructor ()
* connector-net-ref-mysqlclient-mysqlcommandconstructor2::  `MySqlCommand' Constructor (String)
* connector-net-ref-mysqlclient-mysqlcommandconstructor3::  `MySqlCommand' Constructor
* connector-net-ref-mysqlclient-mysqlcommandconstructor4::  `MySqlCommand' Constructor

Initializes a new instance of the *Note MySqlCommand:
connector-net-ref-mysqlclient-mysqlcommand.  class.

*Overload List*

Initializes a new instance of the *Note MySqlCommand:
connector-net-ref-mysqlclient-mysqlcommand.  class.

   * *Note public MySqlCommand();:
     connector-net-ref-mysqlclient-mysqlcommandconstructor1.

   * *Note public MySqlCommand(string);:
     connector-net-ref-mysqlclient-mysqlcommandconstructor2.

   * *Note public MySqlCommand(string:
     (MySqlConnection);)connector-net-ref-mysqlclient-mysqlcommandconstructor3.

   * *Note public MySqlCommand(string:
     (MySqlConnection)connector-net-ref-mysqlclient-mysqlcommandconstructor4.

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandconstructor1,  Next: connector-net-ref-mysqlclient-mysqlcommandconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor,  Up: connector-net-ref-mysqlclient-mysqlcommandconstructor

20.2.4.6 `MySqlCommand' Constructor ()
......................................

Initializes a new instance of the *Note MySqlCommand:
connector-net-ref-mysqlclient-mysqlcommand.  class.

*Syntax: Visual Basic*

     Overloads Public Sub New()

*Syntax: C#*

     public MySqlCommand();

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandconstructor2,  Next: connector-net-ref-mysqlclient-mysqlcommandconstructor3,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor1,  Up: connector-net-ref-mysqlclient-mysqlcommandconstructor

20.2.4.7 `MySqlCommand' Constructor (String)
............................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal cmdText As String _
     )

*Syntax: C#*

     public MySqlCommand(
     stringcmdText
     );

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandconstructor3,  Next: connector-net-ref-mysqlclient-mysqlcommandconstructor4,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor2,  Up: connector-net-ref-mysqlclient-mysqlcommandconstructor

20.2.4.8 `MySqlCommand' Constructor
...................................

* Menu:

* connector-net-ref-mysqlclient-mysqlconnection::  `MySqlConnection' Class

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal cmdText As String, _
        ByVal connection As MySqlConnection _
     )

*Syntax: C#*

     public MySqlCommand(
     stringcmdText,
     MySqlConnectionconnection
     );

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor3,  Up: connector-net-ref-mysqlclient-mysqlcommandconstructor3

20.2.4.9 `MySqlConnection' Class
................................

* Menu:

* connector-net-ref-mysqlclient-mysqlconnectionmembers::  `MySqlConnection' Members

For a list of all members of this type, see *Note MySqlConnection
Members: connector-net-ref-mysqlclient-mysqlconnectionmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlConnection_
       Inherits Component_
       Implements IDbConnection, ICloneable

*Syntax: C#*

     public sealed class MySqlConnection : Component, IDbConnection, ICloneable

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlConnection Members:
connector-net-ref-mysqlclient-mysqlconnectionmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnectionmembers,  Prev: connector-net-ref-mysqlclient-mysqlconnection,  Up: connector-net-ref-mysqlclient-mysqlconnection

20.2.4.10 `MySqlConnection' Members
...................................

* Menu:

* connector-net-ref-mysqlclient-mysqlconnectionconstructor::  `MySqlConnection' Constructor
* connector-net-ref-mysqlclient-mysqlconnection-connectionstring::  ConnectionString Property
* connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout::  ConnectionTimeout Property
* connector-net-ref-mysqlclient-mysqlconnection-database::  Database Property
* connector-net-ref-mysqlclient-mysqlconnection-datasource::  DataSource Property
* connector-net-ref-mysqlclient-mysqlconnection-serverthread::  ServerThread Property
* connector-net-ref-mysqlclient-mysqlconnection-serverversion::  ServerVersion Property
* connector-net-ref-mysqlclient-mysqlconnection-state::  State Property
* connector-net-ref-mysqlclient-mysqlconnection-usecompression::  UseCompression Property
* connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads::  BeginTransaction Method
* connector-net-ref-mysqlclient-mysqlconnection-changedatabase::  `MySqlConnection.ChangeDatabase' Method
* connector-net-ref-mysqlclient-mysqlconnection-close::  `MySqlConnection.Close' Method
* connector-net-ref-mysqlclient-mysqlconnection-createcommand::  `MySqlConnection.CreateCommand' Method
* connector-net-ref-mysqlclient-mysqlconnection-open::  `MySqlConnection.Open' Method
* connector-net-ref-mysqlclient-mysqlconnection-ping::  `MySqlConnection.Ping' Method
* connector-net-ref-mysqlclient-mysqlconnection-infomessage::  `MySqlConnection.InfoMessage' Event
* connector-net-ref-mysqlclient-mysqlconnection-statechange::  `MySqlConnection.StateChange' Event

*Note MySqlConnection overview:
connector-net-ref-mysqlclient-mysqlconnection.

*Public Instance Constructors*

*Note MySqlConnection:               Overloaded. Initializes a new
connector-net-ref-mysqlclient-mysqlconnectionconstructor.instance of the MySqlConnection
                                     class.

*Public Instance Properties*

*Note ConnectionString:              
connector-net-ref-mysqlclient-mysqlconnection-connectionstring.
*Note ConnectionTimeout:             
connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout.
Container(inherited from Component)  Gets the IContainerthat contains
                                     the Component.
*Note Database:                      
connector-net-ref-mysqlclient-mysqlconnection-database.
*Note DataSource:                    Gets the name of the MySQL server
connector-net-ref-mysqlclient-mysqlconnection-datasource.to which to connect.
*Note ServerThread:                  Returns the id of the server thread
connector-net-ref-mysqlclient-mysqlconnection-serverthread.this connection is executing on
*Note ServerVersion:                 
connector-net-ref-mysqlclient-mysqlconnection-serverversion.
Site(inherited from Component)       Gets or sets the ISiteof the
                                     Component.
*Note State:                         
connector-net-ref-mysqlclient-mysqlconnection-state.
*Note UseCompression:                Indicates if this connection should
connector-net-ref-mysqlclient-mysqlconnection-usecompression.use compression when communicating
                                     with the server.

*Public Instance Methods*

*Note BeginTransaction:              Overloaded.
connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads.
*Note ChangeDatabase:                
connector-net-ref-mysqlclient-mysqlconnection-changedatabase.
*Note Close:                         
connector-net-ref-mysqlclient-mysqlconnection-close.
*Note CreateCommand:                 
connector-net-ref-mysqlclient-mysqlconnection-createcommand.
CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
Dispose(inherited from Component)    Releases all resources used by the
                                     Component.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note Open:                          
connector-net-ref-mysqlclient-mysqlconnection-open.
*Note Ping:                          Ping
connector-net-ref-mysqlclient-mysqlconnection-ping.
ToString(inherited from Component)   Returns a Stringcontaining the name
                                     of the Component, if any. This
                                     method should not be overridden.

*Public Instance Events*

Disposed(inherited from Component)   Adds an event handler to listen to
                                     the Disposedevent on the component.
*Note InfoMessage:                   
connector-net-ref-mysqlclient-mysqlconnection-infomessage.
*Note StateChange:                   
connector-net-ref-mysqlclient-mysqlconnection-statechange.

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnectionconstructor,  Next: connector-net-ref-mysqlclient-mysqlconnection-connectionstring,  Prev: connector-net-ref-mysqlclient-mysqlconnectionmembers,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.11 `MySqlConnection' Constructor
.......................................

* Menu:

* connector-net-ref-mysqlclient-mysqlconnectionconstructor1::  `MySqlConnection' Constructor
* connector-net-ref-mysqlclient-mysqlconnectionconstructor2::  `MySqlConnection' Constructor

Initializes a new instance of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  class.

*Overload List*

Initializes a new instance of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  class.

   * *Note public MySqlConnection();:
     connector-net-ref-mysqlclient-mysqlconnectionconstructor1.

   * *Note public MySqlConnection(string);:
     connector-net-ref-mysqlclient-mysqlconnectionconstructor2.

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnectionconstructor1,  Next: connector-net-ref-mysqlclient-mysqlconnectionconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlconnectionconstructor,  Up: connector-net-ref-mysqlclient-mysqlconnectionconstructor

20.2.4.12 `MySqlConnection' Constructor
.......................................

Initializes a new instance of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  class.

*Syntax: Visual Basic*

     Overloads Public Sub New()

*Syntax: C#*

     public MySqlConnection();

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlConnection Constructor Overload List:
connector-net-ref-mysqlclient-mysqlconnectionconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnectionconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlconnectionconstructor1,  Up: connector-net-ref-mysqlclient-mysqlconnectionconstructor

20.2.4.13 `MySqlConnection' Constructor
.......................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal connectionString As String _
     )

*Syntax: C#*

     public MySqlConnection(
     stringconnectionString
     );

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlConnection Constructor Overload List:
connector-net-ref-mysqlclient-mysqlconnectionconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-connectionstring,  Next: connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout,  Prev: connector-net-ref-mysqlclient-mysqlconnectionconstructor,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.14 ConnectionString Property
...................................

*Syntax: Visual Basic*

     NotOverridable Public Property ConnectionString As String _
     _
       Implements IDbConnection.ConnectionString

*Syntax: C#*

     public string ConnectionString {get; set;}

*Implements*

IDbConnection.ConnectionString

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout,  Next: connector-net-ref-mysqlclient-mysqlconnection-database,  Prev: connector-net-ref-mysqlclient-mysqlconnection-connectionstring,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.15 ConnectionTimeout Property
....................................

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property ConnectionTimeout As Integer _
     _
       Implements IDbConnection.ConnectionTimeout

*Syntax: C#*

     public int ConnectionTimeout {get;}

*Implements*

IDbConnection.ConnectionTimeout

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-database,  Next: connector-net-ref-mysqlclient-mysqlconnection-datasource,  Prev: connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.16 Database Property
...........................

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property Database As String _
     _
       Implements IDbConnection.Database

*Syntax: C#*

     public string Database {get;}

*Implements*

IDbConnection.Database

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-datasource,  Next: connector-net-ref-mysqlclient-mysqlconnection-serverthread,  Prev: connector-net-ref-mysqlclient-mysqlconnection-database,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.17 DataSource Property
.............................

Gets the name of the MySQL server to which to connect.

*Syntax: Visual Basic*

     Public ReadOnly Property DataSource As String

*Syntax: C#*

     public string DataSource {get;}

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-serverthread,  Next: connector-net-ref-mysqlclient-mysqlconnection-serverversion,  Prev: connector-net-ref-mysqlclient-mysqlconnection-datasource,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.18 ServerThread Property
...............................

Returns the id of the server thread this connection is executing on

*Syntax: Visual Basic*

     Public ReadOnly Property ServerThread As Integer

*Syntax: C#*

     public int ServerThread {get;}

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-serverversion,  Next: connector-net-ref-mysqlclient-mysqlconnection-state,  Prev: connector-net-ref-mysqlclient-mysqlconnection-serverthread,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.19 ServerVersion Property
................................

*Syntax: Visual Basic*

     Public ReadOnly Property ServerVersion As String

*Syntax: C#*

     public string ServerVersion {get;}

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-state,  Next: connector-net-ref-mysqlclient-mysqlconnection-usecompression,  Prev: connector-net-ref-mysqlclient-mysqlconnection-serverversion,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.20 State Property
........................

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property State As ConnectionState _
     _
       Implements IDbConnection.State

*Syntax: C#*

     public System.Data.ConnectionState State {get;}

*Implements*

IDbConnection.State

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-usecompression,  Next: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads,  Prev: connector-net-ref-mysqlclient-mysqlconnection-state,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.21 UseCompression Property
.................................

Indicates if this connection should use compression when communicating
with the server.

*Syntax: Visual Basic*

     Public ReadOnly Property UseCompression As Boolean

*Syntax: C#*

     public bool UseCompression {get;}

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads,  Next: connector-net-ref-mysqlclient-mysqlconnection-changedatabase,  Prev: connector-net-ref-mysqlclient-mysqlconnection-usecompression,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.22 BeginTransaction Method
.................................

* Menu:

* connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1::  `MySqlConnection.BeginTransaction' Method
* connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-2::  `MySqlConnection.BeginTransaction' Method

*Overload List*

   * *Note public MySqlTransaction BeginTransaction();:
     connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1.

   * *Note public MySqlTransaction BeginTransaction(IsolationLevel);:
     connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-2.

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1,  Next: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads,  Up: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads

20.2.4.23 `MySqlConnection.BeginTransaction' Method
...................................................

* Menu:

* connector-net-ref-mysqlclient-mysqltransaction::  `MySqlTransaction' Class

*Syntax: Visual Basic*

     Overloads Public Function BeginTransaction() As MySqlTransaction

*Syntax: C#*

     public MySqlTransaction BeginTransaction();

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlConnection.BeginTransaction Overload List:
connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransaction,  Prev: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1,  Up: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1

20.2.4.24 `MySqlTransaction' Class
..................................

* Menu:

* connector-net-ref-mysqlclient-mysqltransactionmembers::  `MySqlTransaction' Members

For a list of all members of this type, see *Note MySqlTransaction
Members: connector-net-ref-mysqlclient-mysqltransactionmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlTransaction_
       Implements IDbTransaction, IDisposable

*Syntax: C#*

     public sealed class MySqlTransaction : IDbTransaction, IDisposable

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlTransaction Members:
connector-net-ref-mysqlclient-mysqltransactionmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransactionmembers,  Prev: connector-net-ref-mysqlclient-mysqltransaction,  Up: connector-net-ref-mysqlclient-mysqltransaction

20.2.4.25 `MySqlTransaction' Members
....................................

* Menu:

* connector-net-ref-mysqlclient-mysqltransaction-connection::  Connection Property
* connector-net-ref-mysqlclient-mysqltransaction-isolationlevel::  IsolationLevel Property
* connector-net-ref-mysqlclient-mysqltransaction-commit::  `MySqlTransaction.Commit' Method
* connector-net-ref-mysqlclient-mysqltransaction-rollback::  `MySqlTransaction.Rollback' Method

*Note MySqlTransaction overview:
connector-net-ref-mysqlclient-mysqltransaction.

*Public Instance Properties*

*Note Connection:                    Gets the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqltransaction-connection.connector-net-ref-mysqlclient-mysqlconnection.
                                     object associated with the
                                     transaction, or a null reference
                                     (Nothing in Visual Basic) if the
                                     transaction is no longer valid.
*Note IsolationLevel:                Specifies the IsolationLevelfor
connector-net-ref-mysqlclient-mysqltransaction-isolationlevel.this transaction.

*Public Instance Methods*

*Note Commit:                        
connector-net-ref-mysqlclient-mysqltransaction-commit.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note Rollback:                      
connector-net-ref-mysqlclient-mysqltransaction-rollback.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlTransaction Class:
connector-net-ref-mysqlclient-mysqltransaction , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransaction-connection,  Next: connector-net-ref-mysqlclient-mysqltransaction-isolationlevel,  Prev: connector-net-ref-mysqlclient-mysqltransactionmembers,  Up: connector-net-ref-mysqlclient-mysqltransactionmembers

20.2.4.26 Connection Property
.............................

Gets the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object associated with
the transaction, or a null reference (Nothing in Visual Basic) if the
transaction is no longer valid.

*Syntax: Visual Basic*

     Public ReadOnly Property Connection As MySqlConnection

*Syntax: C#*

     public MySqlConnection Connection {get;}

*Property Value*

The *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object associated with
this transaction.

*Remarks*

A single application may have multiple database connections, each with
zero or more transactions. This property enables you to determine the
connection object associated with a particular transaction created by
*Note BeginTransaction:
connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1
.

*See Also*

*Note MySqlTransaction Class:
connector-net-ref-mysqlclient-mysqltransaction , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransaction-isolationlevel,  Next: connector-net-ref-mysqlclient-mysqltransaction-commit,  Prev: connector-net-ref-mysqlclient-mysqltransaction-connection,  Up: connector-net-ref-mysqlclient-mysqltransactionmembers

20.2.4.27 IsolationLevel Property
.................................

Specifies the IsolationLevelfor this transaction.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property IsolationLevel As IsolationLevel _
     _
       Implements IDbTransaction.IsolationLevel

*Syntax: C#*

     public System.Data.IsolationLevel IsolationLevel {get;}

*Property Value*

The IsolationLevel for this transaction.  The default is ReadCommitted.

*Implements*

IDbTransaction.IsolationLevel

*Remarks*

Parallel transactions are not supported.  Therefore, the IsolationLevel
applies to the entire transaction.

*See Also*

*Note MySqlTransaction Class:
connector-net-ref-mysqlclient-mysqltransaction , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransaction-commit,  Next: connector-net-ref-mysqlclient-mysqltransaction-rollback,  Prev: connector-net-ref-mysqlclient-mysqltransaction-isolationlevel,  Up: connector-net-ref-mysqlclient-mysqltransactionmembers

20.2.4.28 `MySqlTransaction.Commit' Method
..........................................

*Syntax: Visual Basic*

     NotOverridable Public Sub Commit() _
     _
       Implements IDbTransaction.Commit

*Syntax: C#*

     public void Commit();

*Implements*

IDbTransaction.Commit

*See Also*

*Note MySqlTransaction Class:
connector-net-ref-mysqlclient-mysqltransaction , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransaction-rollback,  Prev: connector-net-ref-mysqlclient-mysqltransaction-commit,  Up: connector-net-ref-mysqlclient-mysqltransactionmembers

20.2.4.29 `MySqlTransaction.Rollback' Method
............................................

*Syntax: Visual Basic*

     NotOverridable Public Sub Rollback() _
     _
       Implements IDbTransaction.Rollback

*Syntax: C#*

     public void Rollback();

*Implements*

IDbTransaction.Rollback

*See Also*

*Note MySqlTransaction Class:
connector-net-ref-mysqlclient-mysqltransaction , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1,  Up: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads

20.2.4.30 `MySqlConnection.BeginTransaction' Method
...................................................

*Syntax: Visual Basic*

     Overloads Public Function BeginTransaction( _
        ByVal iso As IsolationLevel _
     ) As MySqlTransaction

*Syntax: C#*

     public MySqlTransaction BeginTransaction(
     IsolationLeveliso
     );

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlConnection.BeginTransaction Overload List:
connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-changedatabase,  Next: connector-net-ref-mysqlclient-mysqlconnection-close,  Prev: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.31 `MySqlConnection.ChangeDatabase' Method
.................................................

*Syntax: Visual Basic*

     NotOverridable Public Sub ChangeDatabase( _
        ByVal databaseName As String _
     ) _
     _
       Implements IDbConnection.ChangeDatabase

*Syntax: C#*

     public void ChangeDatabase(
     stringdatabaseName
     );

*Implements*

IDbConnection.ChangeDatabase

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-close,  Next: connector-net-ref-mysqlclient-mysqlconnection-createcommand,  Prev: connector-net-ref-mysqlclient-mysqlconnection-changedatabase,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.32 `MySqlConnection.Close' Method
........................................

*Syntax: Visual Basic*

     NotOverridable Public Sub Close() _
     _
       Implements IDbConnection.Close

*Syntax: C#*

     public void Close();

*Implements*

IDbConnection.Close

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-createcommand,  Next: connector-net-ref-mysqlclient-mysqlconnection-open,  Prev: connector-net-ref-mysqlclient-mysqlconnection-close,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.33 `MySqlConnection.CreateCommand' Method
................................................

*Syntax: Visual Basic*

     Public Function CreateCommand() As MySqlCommand

*Syntax: C#*

     public MySqlCommand CreateCommand();

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-open,  Next: connector-net-ref-mysqlclient-mysqlconnection-ping,  Prev: connector-net-ref-mysqlclient-mysqlconnection-createcommand,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.34 `MySqlConnection.Open' Method
.......................................

*Syntax: Visual Basic*

     NotOverridable Public Sub Open() _
     _
       Implements IDbConnection.Open

*Syntax: C#*

     public void Open();

*Implements*

IDbConnection.Open

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-ping,  Next: connector-net-ref-mysqlclient-mysqlconnection-infomessage,  Prev: connector-net-ref-mysqlclient-mysqlconnection-open,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.35 `MySqlConnection.Ping' Method
.......................................

Ping

*Syntax: Visual Basic*

     Public Function Ping() As Boolean

*Syntax: C#*

     public bool Ping();

*Return Value*

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-infomessage,  Next: connector-net-ref-mysqlclient-mysqlconnection-statechange,  Prev: connector-net-ref-mysqlclient-mysqlconnection-ping,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.36 `MySqlConnection.InfoMessage' Event
.............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlinfomessageeventhandler::  `MySqlInfoMessageEventHandler' Delegate

*Syntax: Visual Basic*

     Public Event InfoMessage As MySqlInfoMessageEventHandler

*Syntax: C#*

     public event MySqlInfoMessageEventHandler InfoMessage;

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlinfomessageeventhandler,  Prev: connector-net-ref-mysqlclient-mysqlconnection-infomessage,  Up: connector-net-ref-mysqlclient-mysqlconnection-infomessage

20.2.4.37 `MySqlInfoMessageEventHandler' Delegate
.................................................

* Menu:

* connector-net-ref-mysqlclient-mysqlinfomessageeventargs::  `MySqlInfoMessageEventArgs' Class

Represents the method that will handle the *Note InfoMessage:
connector-net-ref-mysqlclient-mysqlconnection-infomessage.  event of a
*Note MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection .

*Syntax: Visual Basic*

     Public Delegate Sub MySqlInfoMessageEventHandler( _
        ByVal sender As Object, _
        ByVal args As MySqlInfoMessageEventArgs _
     )

*Syntax: C#*

     public delegate void MySqlInfoMessageEventHandler(
     objectsender,
     MySqlInfoMessageEventArgsargs
     );

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargs,  Prev: connector-net-ref-mysqlclient-mysqlinfomessageeventhandler,  Up: connector-net-ref-mysqlclient-mysqlinfomessageeventhandler

20.2.4.38 `MySqlInfoMessageEventArgs' Class
...........................................

* Menu:

* connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers::  `MySqlInfoMessageEventArgs' Members

Provides data for the InfoMessage event. This class cannot be inherited.

For a list of all members of this type, see *Note
MySqlInfoMessageEventArgs Members:
connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers .

*Syntax: Visual Basic*

     Public Class MySqlInfoMessageEventArgs_
       Inherits EventArgs

*Syntax: C#*

     public class MySqlInfoMessageEventArgs : EventArgs

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlInfoMessageEventArgs Members:
connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers,  Prev: connector-net-ref-mysqlclient-mysqlinfomessageeventargs,  Up: connector-net-ref-mysqlclient-mysqlinfomessageeventargs

20.2.4.39 `MySqlInfoMessageEventArgs' Members
.............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlinfomessageeventargsconstructor::  `MySqlInfoMessageEventArgs' Constructor
* connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors::  `MySqlInfoMessageEventArgs.errors' Field

*Note MySqlInfoMessageEventArgs overview:
connector-net-ref-mysqlclient-mysqlinfomessageeventargs.

*Public Instance Constructors*

*Note MySqlInfoMessageEventArgs      Initializes a new instance of the
Constructor:                         *Note MySqlInfoMessageEventArgs:
connector-net-ref-mysqlclient-mysqlinfomessageeventargsconstructor.connector-net-ref-mysqlclient-mysqlinfomessageeventargs.
                                     class.

*Public Instance Fields*

*Note errors:                        
connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors.

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*Protected Instance Methods*

Finalize(inherited from Object)      Allows an Objectto attempt to free
                                     resources and perform other cleanup
                                     operations before the Objectis
                                     reclaimed by garbage collection.
MemberwiseClone(inherited from       Creates a shallow copy of the
Object)                              current Object.

*See Also*

*Note MySqlInfoMessageEventArgs Class:
connector-net-ref-mysqlclient-mysqlinfomessageeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargsconstructor,  Next: connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors,  Prev: connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers,  Up: connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers

20.2.4.40 `MySqlInfoMessageEventArgs' Constructor
.................................................

Initializes a new instance of the *Note MySqlInfoMessageEventArgs:
connector-net-ref-mysqlclient-mysqlinfomessageeventargs.  class.

*Syntax: Visual Basic*

     Public Sub New()

*Syntax: C#*

     public MySqlInfoMessageEventArgs();

*See Also*

*Note MySqlInfoMessageEventArgs Class:
connector-net-ref-mysqlclient-mysqlinfomessageeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors,  Prev: connector-net-ref-mysqlclient-mysqlinfomessageeventargsconstructor,  Up: connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers

20.2.4.41 `MySqlInfoMessageEventArgs.errors' Field
..................................................

* Menu:

* connector-net-ref-mysqlclient-mysqlerror::  `MySqlError' Class

*Syntax: Visual Basic*

     Public errors As MySqlError()

*Syntax: C#*

     public MySqlError[] errors;

*See Also*

*Note MySqlInfoMessageEventArgs Class:
connector-net-ref-mysqlclient-mysqlinfomessageeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerror,  Prev: connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors,  Up: connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors

20.2.4.42 `MySqlError' Class
............................

* Menu:

* connector-net-ref-mysqlclient-mysqlerrormembers::  `MySqlError' Members

Collection of error codes that can be returned by the server

For a list of all members of this type, see *Note MySqlError Members:
connector-net-ref-mysqlclient-mysqlerrormembers .

*Syntax: Visual Basic*

     Public Class MySqlError

*Syntax: C#*

     public class MySqlError

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe for
multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlError Members:
connector-net-ref-mysqlclient-mysqlerrormembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerrormembers,  Prev: connector-net-ref-mysqlclient-mysqlerror,  Up: connector-net-ref-mysqlclient-mysqlerror

20.2.4.43 `MySqlError' Members
..............................

* Menu:

* connector-net-ref-mysqlclient-mysqlerrorconstructor::  `MySqlError' Constructor
* connector-net-ref-mysqlclient-mysqlerror-code::  Code Property
* connector-net-ref-mysqlclient-mysqlerror-level::  Level Property
* connector-net-ref-mysqlclient-mysqlerror-message::  Message Property

*Note MySqlError overview: connector-net-ref-mysqlclient-mysqlerror.

*Public Instance Constructors*

*Note MySqlError Constructor:        
connector-net-ref-mysqlclient-mysqlerrorconstructor.

*Public Instance Properties*

*Note Code:                          Error code
connector-net-ref-mysqlclient-mysqlerror-code.
*Note Level:                         Error level
connector-net-ref-mysqlclient-mysqlerror-level.
*Note Message:                       Error message
connector-net-ref-mysqlclient-mysqlerror-message.

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*Protected Instance Methods*

Finalize(inherited from Object)      Allows an Objectto attempt to free
                                     resources and perform other cleanup
                                     operations before the Objectis
                                     reclaimed by garbage collection.
MemberwiseClone(inherited from       Creates a shallow copy of the
Object)                              current Object.

*See Also*

*Note MySqlError Class: connector-net-ref-mysqlclient-mysqlerror ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerrorconstructor,  Next: connector-net-ref-mysqlclient-mysqlerror-code,  Prev: connector-net-ref-mysqlclient-mysqlerrormembers,  Up: connector-net-ref-mysqlclient-mysqlerrormembers

20.2.4.44 `MySqlError' Constructor
..................................

*Syntax: Visual Basic*

     Public Sub New( _
        ByVal level As String, _
        ByVal code As Integer, _
        ByVal message As String _
     )

*Syntax: C#*

     public MySqlError(
     stringlevel,
     intcode,
     stringmessage
     );

*Parameters*

   * `level':

   * `code':

   * `message':

*See Also*

*Note MySqlError Class: connector-net-ref-mysqlclient-mysqlerror ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerror-code,  Next: connector-net-ref-mysqlclient-mysqlerror-level,  Prev: connector-net-ref-mysqlclient-mysqlerrorconstructor,  Up: connector-net-ref-mysqlclient-mysqlerrormembers

20.2.4.45 Code Property
.......................

Error code

*Syntax: Visual Basic*

     Public ReadOnly Property Code As Integer

*Syntax: C#*

     public int Code {get;}

*See Also*

*Note MySqlError Class: connector-net-ref-mysqlclient-mysqlerror ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerror-level,  Next: connector-net-ref-mysqlclient-mysqlerror-message,  Prev: connector-net-ref-mysqlclient-mysqlerror-code,  Up: connector-net-ref-mysqlclient-mysqlerrormembers

20.2.4.46 Level Property
........................

Error level

*Syntax: Visual Basic*

     Public ReadOnly Property Level As String

*Syntax: C#*

     public string Level {get;}

*See Also*

*Note MySqlError Class: connector-net-ref-mysqlclient-mysqlerror ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerror-message,  Prev: connector-net-ref-mysqlclient-mysqlerror-level,  Up: connector-net-ref-mysqlclient-mysqlerrormembers

20.2.4.47 Message Property
..........................

Error message

*Syntax: Visual Basic*

     Public ReadOnly Property Message As String

*Syntax: C#*

     public string Message {get;}

*See Also*

*Note MySqlError Class: connector-net-ref-mysqlclient-mysqlerror ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-statechange,  Prev: connector-net-ref-mysqlclient-mysqlconnection-infomessage,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

20.2.4.48 `MySqlConnection.StateChange' Event
.............................................

*Syntax: Visual Basic*

     Public Event StateChange As StateChangeEventHandler

*Syntax: C#*

     public event StateChangeEventHandler StateChange;

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandconstructor4,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor3,  Up: connector-net-ref-mysqlclient-mysqlcommandconstructor

20.2.4.49 `MySqlCommand' Constructor
....................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal cmdText As String, _
        ByVal connection As MySqlConnection, _
        ByVal transaction As MySqlTransaction _
     )

*Syntax: C#*

     public MySqlCommand(
     stringcmdText,
     MySqlConnectionconnection,
     MySqlTransactiontransaction
     );

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-commandtext,  Next: connector-net-ref-mysqlclient-mysqlcommand-commandtimeout,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.50 CommandText Property
..............................

*Syntax: Visual Basic*

     NotOverridable Public Property CommandText As String _
     _
       Implements IDbCommand.CommandText

*Syntax: C#*

     public string CommandText {get; set;}

*Implements*

IDbCommand.CommandText

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-commandtimeout,  Next: connector-net-ref-mysqlclient-mysqlcommand-commandtype,  Prev: connector-net-ref-mysqlclient-mysqlcommand-commandtext,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.51 CommandTimeout Property
.................................

*Syntax: Visual Basic*

     NotOverridable Public Property CommandTimeout As Integer _
     _
       Implements IDbCommand.CommandTimeout

*Syntax: C#*

     public int CommandTimeout {get; set;}

*Implements*

IDbCommand.CommandTimeout

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-commandtype,  Next: connector-net-ref-mysqlclient-mysqlcommand-connection,  Prev: connector-net-ref-mysqlclient-mysqlcommand-commandtimeout,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.52 CommandType Property
..............................

*Syntax: Visual Basic*

     NotOverridable Public Property CommandType As CommandType _
     _
       Implements IDbCommand.CommandType

*Syntax: C#*

     public System.Data.CommandType CommandType {get; set;}

*Implements*

IDbCommand.CommandType

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-connection,  Next: connector-net-ref-mysqlclient-mysqlcommand-isprepared,  Prev: connector-net-ref-mysqlclient-mysqlcommand-commandtype,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.53 Connection Property
.............................

*Syntax: Visual Basic*

     Public Property Connection As MySqlConnection

*Syntax: C#*

     public MySqlConnection Connection {get; set;}

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-isprepared,  Next: connector-net-ref-mysqlclient-mysqlcommand-parameters,  Prev: connector-net-ref-mysqlclient-mysqlcommand-connection,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.54 IsPrepared Property
.............................

*Syntax: Visual Basic*

     Public ReadOnly Property IsPrepared As Boolean

*Syntax: C#*

     public bool IsPrepared {get;}

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-parameters,  Next: connector-net-ref-mysqlclient-mysqlcommand-transaction,  Prev: connector-net-ref-mysqlclient-mysqlcommand-isprepared,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.55 Parameters Property
.............................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollection::  `MySqlParameterCollection' Class

*Syntax: Visual Basic*

     Public ReadOnly Property Parameters As MySqlParameterCollection

*Syntax: C#*

     public MySqlParameterCollection Parameters {get;}

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection,  Prev: connector-net-ref-mysqlclient-mysqlcommand-parameters,  Up: connector-net-ref-mysqlclient-mysqlcommand-parameters

20.2.4.56 `MySqlParameterCollection' Class
..........................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollectionmembers::  `MySqlParameterCollection' Members

Represents a collection of parameters relevant to a *Note MySqlCommand:
connector-net-ref-mysqlclient-mysqlcommand.  as well as their
respective mappings to columns in a DataSet. This class cannot be
inherited.

For a list of all members of this type, see *Note
MySqlParameterCollection Members:
connector-net-ref-mysqlclient-mysqlparametercollectionmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlParameterCollection_
       Inherits MarshalByRefObject_
       Implements IDataParameterCollection, IList, ICollection, IEnumerable

*Syntax: C#*

     public sealed class MySqlParameterCollection : MarshalByRefObject, IDataParameterCollection, IList, ICollection, IEnumerable

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlParameterCollection Members:
connector-net-ref-mysqlclient-mysqlparametercollectionmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollectionmembers,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection,  Up: connector-net-ref-mysqlclient-mysqlparametercollection

20.2.4.57 `MySqlParameterCollection' Members
............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollectionconstructor::  `MySqlParameterCollection' Constructor
* connector-net-ref-mysqlclient-mysqlparametercollection-count::  Count Property
* connector-net-ref-mysqlclient-mysqlparametercollectionitem::  Item Property
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads::  Add Method
* connector-net-ref-mysqlclient-mysqlparametercollection-clear::  `MySqlParameterCollection.Clear' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads::  Contains Method
* connector-net-ref-mysqlclient-mysqlparametercollection-copyto::  `MySqlParameterCollection.CopyTo' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads::  IndexOf Method
* connector-net-ref-mysqlclient-mysqlparametercollection-insert::  `MySqlParameterCollection.Insert' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-remove::  `MySqlParameterCollection.Remove' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads::  RemoveAt Method

*Note MySqlParameterCollection overview:
connector-net-ref-mysqlclient-mysqlparametercollection.

*Public Instance Constructors*

*Note MySqlParameterCollection       Initializes a new instance of the
Constructor:                         *Note MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollectionconstructor.connector-net-ref-mysqlclient-mysqlparametercollection.
                                     class.

*Public Instance Properties*

*Note Count:                         Gets the number of MySqlParameter
connector-net-ref-mysqlclient-mysqlparametercollection-count.objects in the collection.
*Note Item:                          Overloaded. Gets the *Note
connector-net-ref-mysqlclient-mysqlparametercollectionitem.MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     with a specified attribute. In C#,
                                     this property is the indexer for the
                                     *Note MySqlParameterCollection:
                                     connector-net-ref-mysqlclient-mysqlparametercollection.
                                     class.

*Public Instance Methods*

*Note Add:                           Overloaded. Adds the specified
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.*Note MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     object to the *Note
                                     MySqlParameterCollection:
                                     connector-net-ref-mysqlclient-mysqlparametercollection
                                     .
*Note Clear:                         Removes all items from the
connector-net-ref-mysqlclient-mysqlparametercollection-clear.collection.
*Note Contains:                      Overloaded. Gets a value indicating
connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads.whether a *Note MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     exists in the collection.
*Note CopyTo:                        Copies MySqlParameter objects from
connector-net-ref-mysqlclient-mysqlparametercollection-copyto.the MySqlParameterCollection to the
                                     specified array.
CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note IndexOf:                       Overloaded. Gets the location of a
connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads.*Note MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     in the collection.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note Insert:                        Inserts a MySqlParameter into the
connector-net-ref-mysqlclient-mysqlparametercollection-insert.collection at the specified index.
*Note Remove:                        Removes the specified
connector-net-ref-mysqlclient-mysqlparametercollection-remove.MySqlParameter from the collection.
*Note RemoveAt:                      Overloaded. Removes the specified
connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads.*Note MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     from the collection.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollectionconstructor,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-count,  Prev: connector-net-ref-mysqlclient-mysqlparametercollectionmembers,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.58 `MySqlParameterCollection' Constructor
................................................

Initializes a new instance of the *Note MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  class.

*Syntax: Visual Basic*

     Public Sub New()

*Syntax: C#*

     public MySqlParameterCollection();

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-count,  Next: connector-net-ref-mysqlclient-mysqlparametercollectionitem,  Prev: connector-net-ref-mysqlclient-mysqlparametercollectionconstructor,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.59 Count Property
........................

Gets the number of MySqlParameter objects in the collection.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property Count As Integer _
     _
       Implements ICollection.Count

*Syntax: C#*

     public int Count {get;}

*Implements*

ICollection.Count

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollectionitem,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-count,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.60 Item Property
.......................

* Menu:

* connector-net-ref-mysqlclient-mysqlparameter::  `MySqlParameter' Class
* connector-net-ref-mysqlclient-mysqlparametercollection-item1::  Item Property (Int32)
* connector-net-ref-mysqlclient-mysqlparametercollection-item2::  Item Property (String)

Gets the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  with a specified
attribute. In C#, this property is the indexer for the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  class.

*Overload List*

Gets the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  at the specified index.

   * *Note public MySqlParameter this[int] {get; set;}:
     connector-net-ref-mysqlclient-mysqlparametercollection-item1.

Gets the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  with the specified name.

   * *Note public MySqlParameter this[string] {get; set;}:
     connector-net-ref-mysqlclient-mysqlparametercollection-item2.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-item1,  Prev: connector-net-ref-mysqlclient-mysqlparametercollectionitem,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionitem

20.2.4.61 `MySqlParameter' Class
................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametermembers::  `MySqlParameter' Members

Represents a parameter to a *Note MySqlCommand:
connector-net-ref-mysqlclient-mysqlcommand , and optionally, its
mapping to DataSetcolumns.  This class cannot be inherited.

For a list of all members of this type, see *Note MySqlParameter
Members: connector-net-ref-mysqlclient-mysqlparametermembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlParameter_
       Inherits MarshalByRefObject_
       Implements IDataParameter, IDbDataParameter, ICloneable

*Syntax: C#*

     public sealed class MySqlParameter : MarshalByRefObject, IDataParameter, IDbDataParameter, ICloneable

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations.  Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlParameter Members:
connector-net-ref-mysqlclient-mysqlparametermembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametermembers,  Prev: connector-net-ref-mysqlclient-mysqlparameter,  Up: connector-net-ref-mysqlclient-mysqlparameter

20.2.4.62 `MySqlParameter' Members
..................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparameterconstructor::  `MySqlParameter' Constructor
* connector-net-ref-mysqlclient-mysqlparameter-dbtype::  DbType Property
* connector-net-ref-mysqlclient-mysqlparameter-direction::  Direction Property
* connector-net-ref-mysqlclient-mysqlparameter-isnullable::  IsNullable Property
* connector-net-ref-mysqlclient-mysqlparameter-isunsigned::  IsUnsigned Property
* connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype::  `MySqlDbType' Property
* connector-net-ref-mysqlclient-mysqlparameter-parametername::  ParameterName Property
* connector-net-ref-mysqlclient-mysqlparameter-precision::  Precision Property
* connector-net-ref-mysqlclient-mysqlparameter-scale::  Scale Property
* connector-net-ref-mysqlclient-mysqlparameter-size::  Size Property
* connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn::  SourceColumn Property
* connector-net-ref-mysqlclient-mysqlparameter-sourceversion::  SourceVersion Property
* connector-net-ref-mysqlclient-mysqlparameter-tostring::  `MySqlParameter.ToString' Method

*Note MySqlParameter overview:
connector-net-ref-mysqlclient-mysqlparameter.

*Public Instance Constructors*

*Note MySqlParameter:                Overloaded. Initializes a new
connector-net-ref-mysqlclient-mysqlparameterconstructor.instance of the MySqlParameter
                                     class.

*Public Instance Properties*

*Note DbType:                        Gets or sets the DbTypeof the
connector-net-ref-mysqlclient-mysqlparameter-dbtype.parameter.
*Note Direction:                     Gets or sets a value indicating
connector-net-ref-mysqlclient-mysqlparameter-direction.whether the parameter is input-only,
                                     output-only, bidirectional, or a
                                     stored procedure return value
                                     parameter. As of MySQL version 4.1
                                     and earlier, input-only is the only
                                     valid choice.
*Note IsNullable:                    Gets or sets a value indicating
connector-net-ref-mysqlclient-mysqlparameter-isnullable.whether the parameter accepts null
                                     values.
*Note IsUnsigned:                    
connector-net-ref-mysqlclient-mysqlparameter-isunsigned.
*Note MySqlDbType:                   Gets or sets the MySqlDbType of the
connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype.parameter.
*Note ParameterName:                 Gets or sets the name of the
connector-net-ref-mysqlclient-mysqlparameter-parametername.MySqlParameter.
*Note Precision:                     Gets or sets the maximum number of
connector-net-ref-mysqlclient-mysqlparameter-precision.digits used to represent the *Note
                                     Value:
                                     connector-net-ref-mysqlclient-mysqlparameter-value.
                                     property.
*Note Scale:                         Gets or sets the number of decimal
connector-net-ref-mysqlclient-mysqlparameter-scale.places to which *Note Value:
                                     connector-net-ref-mysqlclient-mysqlparameter-value.
                                     is resolved.
*Note Size:                          Gets or sets the maximum size, in
connector-net-ref-mysqlclient-mysqlparameter-size.bytes, of the data within the
                                     column.
*Note SourceColumn:                  Gets or sets the name of the source
connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn.column that is mapped to the
                                     DataSetand used for loading or
                                     returning the *Note Value:
                                     connector-net-ref-mysqlclient-mysqlparameter-value
                                     .
*Note SourceVersion:                 Gets or sets the DataRowVersionto
connector-net-ref-mysqlclient-mysqlparameter-sourceversion.use when loading *Note Value:
                                     connector-net-ref-mysqlclient-mysqlparameter-value
                                     .
*Note Value:                         Gets or sets the value of the
connector-net-ref-mysqlclient-mysqlparameter-value.parameter.

*Public Instance Methods*

CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to communicate
                                     with a remote object.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note ToString:                      Overridden. Gets a string
connector-net-ref-mysqlclient-mysqlparameter-tostring.containing the *Note ParameterName:
                                     connector-net-ref-mysqlclient-mysqlparameter-parametername
                                     .

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor,  Next: connector-net-ref-mysqlclient-mysqlparameter-dbtype,  Prev: connector-net-ref-mysqlclient-mysqlparametermembers,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.63 `MySqlParameter' Constructor
......................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparameterconstructor1::  `MySqlParameter' Constructor ()
* connector-net-ref-mysqlclient-mysqlparameterconstructor3::  `MySqlParameter' Constructor
* connector-net-ref-mysqlclient-mysqlparameterconstructor4::  `MySqlParameter' Constructor (String, MySqlDbType, Int32)
* connector-net-ref-mysqlclient-mysqlparameterconstructor6::  `MySqlParameter' Constructor
* connector-net-ref-mysqlclient-mysqlparameterconstructor5::  `MySqlParameter' Constructor
* connector-net-ref-mysqlclient-mysqlparameterconstructor2::  `MySqlParameter' Constructor

Initializes a new instance of the MySqlParameter class.

*Overload List*

Initializes a new instance of the MySqlParameter class.

   * *Note public MySqlParameter();:
     connector-net-ref-mysqlclient-mysqlparameterconstructor1.

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name and the data type.

   * *Note public MySqlParameter(string:
     (MySqlDbType);)connector-net-ref-mysqlclient-mysqlparameterconstructor3.

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the *Note MySqlDbType: connector-net-ref-mysqlclient-mysqldbtype
, and the size.

   * *Note public MySqlParameter(string:
     (MySqlDbType)connector-net-ref-mysqlclient-mysqlparameterconstructor4.

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the type of the parameter, the size of the parameter, a
ParameterDirection, the precision of the parameter, the scale of the
parameter, the source column, a DataRowVersionto use, and the value of
the parameter.

   * *Note public MySqlParameter(string:
     (MySqlDbType)connector-net-ref-mysqlclient-mysqlparameterconstructor6.ParameterDirection,bool,byte,byte,string,DataRowVersion,object);

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the *Note MySqlDbType: connector-net-ref-mysqlclient-mysqldbtype
, the size, and the source column name.

   * *Note public MySqlParameter(string:
     (MySqlDbType)connector-net-ref-mysqlclient-mysqlparameterconstructor5.string);

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name and a value of the new MySqlParameter.

   * *Note public MySqlParameter(string:
     (object);)connector-net-ref-mysqlclient-mysqlparameterconstructor2.

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor1,  Next: connector-net-ref-mysqlclient-mysqlparameterconstructor3,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

20.2.4.64 `MySqlParameter' Constructor ()
.........................................

Initializes a new instance of the MySqlParameter class.

*Syntax: Visual Basic*

     Overloads Public Sub New()

*Syntax: C#*

     public MySqlParameter();

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor3,  Next: connector-net-ref-mysqlclient-mysqlparameterconstructor4,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor1,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

20.2.4.65 `MySqlParameter' Constructor
......................................

* Menu:

* connector-net-ref-mysqlclient-mysqldbtype::  `MySqlDbType' Enumeration

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name and the data type.

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType _
     )

*Syntax: C#*

     public MySqlParameter(
     stringparameterName,
     MySqlDbTypedbType
     );

*Parameters*

   * `parameterName': The name of the parameter to map.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldbtype,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor3,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor3

20.2.4.66 `MySqlDbType' Enumeration
...................................

Specifies MySQL specific data type of a field, property, for use in a
*Note MySqlParameter: connector-net-ref-mysqlclient-mysqlparameter .

*Syntax: Visual Basic*

     Public Enum MySqlDbType

*Syntax: C#*

     public enum MySqlDbType

*Members*

*Member Name*                        *Description*
Newdate                              Obsolete. Use Datetime or Date type.
Timestamp                            A timestamp. The range is
                                     '1970-01-01 00:00:01' to sometime
                                     in the year 2038.
Time                                 The range is '-838:59:59' to
                                     '838:59:59'
Date                                 Date The supported range is
                                     '1000-01-01' to '9999-12-31'
Datetime                             The supported range is '1000-01-01
                                     00:00:00' to '9999-12-31 23:59:59'
Year                                 A year in 2- or 4-digit format
                                     (default is 4-digit). The allowable
                                     values are 1901 to 2155, 0000 in
                                     the 4-digit year format, and
                                     1970-2069 if you use the 2-digit
                                     format (70-69).
TinyBlob                             A BLOB column with a maximum length
                                     of 255 (2^8 - 1) characters
Blob                                 A BLOB column with a maximum length
                                     of 65535 (2^16 - 1) characters
MediumBlob                           A BLOB column with a maximum length
                                     of 16777215 (2^24 - 1) characters
LongBlob                             A BLOB column with a maximum length
                                     of 4294967295 or 4G (2^32 - 1)
                                     characters
Int16                                A 16-bit signed integer. The signed
                                     range is -32768 to 32767.  The
                                     unsigned range is 0 to 65535
Int24                                Specifies a 24 (3 byte) signed or
                                     unsigned value
Int32                                A 32-bit signed integer
Int64                                A 64-bit signed integer
Byte                                 The signed range is -128 to 127.
                                     The unsigned range is 0 to 255.
Float                                A small (single-precision)
                                     floating-point number. Allowable
                                     values are -3.402823466E+38 to
                                     -1.175494351E-38, 0, and
                                     1.175494351E-38 to 3.402823466E+38.
Double                               A normal-size (double-precision)
                                     floating-point number. Allowable
                                     values are -1.7976931348623157E+308
                                     to -2.2250738585072014E-308, 0, and
                                     2.2250738585072014E-308 to
                                     1.7976931348623157E+308.
UByte                                An 8-bit unsigned value
UInt16                               A 16-bit unsigned value
UInt24                               A 24-bit unsigned value
UInt32                               A 32-bit unsigned value
UInt64                               A 64-bit unsigned value
Decimal                              A fixed precision and scale numeric
                                     value between -1038 -1 and 10 38 -1
NewDecimal                           New Decimal
Set                                  A set. A string object that can
                                     have zero or more values, each of
                                     which must be chosen from the list
                                     of values 'value1', 'value2', ... A
                                     SET can have a maximum of 64
                                     members.
String                               Obsolete Use VarChar type
VarChar                              A variable-length string containing
                                     0 to 255 characters
VarString                            A variable-length string containing
                                     0 to 65535 characters
Enum                                 An enumeration. A string object
                                     that can have only one value, chosen
                                     from the list of values 'value1',
                                     'value2', ..., NULL or the special
                                     "" error value. An ENUM can have a
                                     maximum of 65535 distinct values.
Geometry                             
Bit                                  Bit-field data type
TinyText                             A nonbinary string column
                                     supporting a maximum length of 255
                                     (2^8 - 1) characters
Text                                 A nonbinary string column
                                     supporting a maximum length of
                                     65535 (2^16 - 1) characters
MediumText                           A nonbinary string column
                                     supporting a maximum length of
                                     16777215 (2^24 - 1) characters
LongText                             A nonbinary string column
                                     supporting a maximum length of
                                     4294967295 (2^32 - 1) characters

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor4,  Next: connector-net-ref-mysqlclient-mysqlparameterconstructor6,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor3,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

20.2.4.67 `MySqlParameter' Constructor (String, MySqlDbType, Int32)
...................................................................

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the *Note MySqlDbType: connector-net-ref-mysqlclient-mysqldbtype
, and the size.

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType, _
        ByVal size As Integer _
     )

*Syntax: C#*

     public MySqlParameter(
     stringparameterName,
     MySqlDbTypedbType,
     intsize
     );

*Parameters*

   * `parameterName': The name of the parameter to map.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

   * `size': The length of the parameter.

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor6,  Next: connector-net-ref-mysqlclient-mysqlparameterconstructor5,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor4,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

20.2.4.68 `MySqlParameter' Constructor
......................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparameter-value::  Value Property

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the type of the parameter, the size of the parameter, a
ParameterDirection, the precision of the parameter, the scale of the
parameter, the source column, a DataRowVersionto use, and the value of
the parameter.

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType, _
        ByVal size As Integer, _
        ByVal direction As ParameterDirection, _
        ByVal isNullable As Boolean, _
        ByVal precision As Byte, _
        ByVal scale As Byte, _
        ByVal sourceColumn As String, _
        ByVal sourceVersion As DataRowVersion, _
        ByVal value As Object _
     )

*Syntax: C#*

     public MySqlParameter(
     stringparameterName,
     MySqlDbTypedbType,
     intsize,
     ParameterDirectiondirection,
     boolisNullable,
     byteprecision,
     bytescale,
     stringsourceColumn,
     DataRowVersionsourceVersion,
     objectvalue
     );

*Parameters*

   * `parameterName': The name of the parameter to map.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

   * `size': The length of the parameter.

   * `direction': One of the ParameterDirectionvalues.

   * `isNullable': true if the value of the field can be null,
     otherwise false.

   * `precision': The total number of digits to the left and right of
     the decimal point to which *Note Value:
     connector-net-ref-mysqlclient-mysqlparameter-value.  is resolved.

   * `scale': The total number of decimal places to which *Note Value:
     connector-net-ref-mysqlclient-mysqlparameter-value.  is resolved.

   * `sourceColumn': The name of the source column.

   * `sourceVersion': One of the DataRowVersionvalues.

   * `value': An Objectthat is the value of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter .

*Exceptions*

*Exception Type*                     *Condition*
ArgumentException                    

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-value,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor6,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor6

20.2.4.69 Value Property
........................

Gets or sets the value of the parameter.

*Syntax: Visual Basic*

     NotOverridable Public Property Value As Object _
     _
       Implements IDataParameter.Value

*Syntax: C#*

     public object Value {get; set;}

*Implements*

IDataParameter.Value

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor5,  Next: connector-net-ref-mysqlclient-mysqlparameterconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor6,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

20.2.4.70 `MySqlParameter' Constructor
......................................

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the *Note MySqlDbType: connector-net-ref-mysqlclient-mysqldbtype
, the size, and the source column name.

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType, _
        ByVal size As Integer, _
        ByVal sourceColumn As String _
     )

*Syntax: C#*

     public MySqlParameter(
     stringparameterName,
     MySqlDbTypedbType,
     intsize,
     stringsourceColumn
     );

*Parameters*

   * `parameterName': The name of the parameter to map.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

   * `size': The length of the parameter.

   * `sourceColumn': The name of the source column.

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor5,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

20.2.4.71 `MySqlParameter' Constructor
......................................

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name and a value of the new MySqlParameter.

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal parameterName As String, _
        ByVal value As Object _
     )

*Syntax: C#*

     public MySqlParameter(
     stringparameterName,
     objectvalue
     );

*Parameters*

   * `parameterName': The name of the parameter to map.

   * `value': An Objectthat is the value of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter .

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-dbtype,  Next: connector-net-ref-mysqlclient-mysqlparameter-direction,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.72 DbType Property
.........................

Gets or sets the DbTypeof the parameter.

*Syntax: Visual Basic*

     NotOverridable Public Property DbType As DbType _
     _
       Implements IDataParameter.DbType

*Syntax: C#*

     public System.Data.DbType DbType {get; set;}

*Implements*

IDataParameter.DbType

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-direction,  Next: connector-net-ref-mysqlclient-mysqlparameter-isnullable,  Prev: connector-net-ref-mysqlclient-mysqlparameter-dbtype,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.73 Direction Property
............................

Gets or sets a value indicating whether the parameter is input-only,
output-only, bidirectional, or a stored procedure return value
parameter. As of MySQL version 4.1 and earlier, input-only is the only
valid choice.

*Syntax: Visual Basic*

     NotOverridable Public Property Direction As ParameterDirection _
     _
       Implements IDataParameter.Direction

*Syntax: C#*

     public System.Data.ParameterDirection Direction {get; set;}

*Implements*

IDataParameter.Direction

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-isnullable,  Next: connector-net-ref-mysqlclient-mysqlparameter-isunsigned,  Prev: connector-net-ref-mysqlclient-mysqlparameter-direction,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.74 IsNullable Property
.............................

Gets or sets a value indicating whether the parameter accepts null
values.

*Syntax: Visual Basic*

     NotOverridable Public Property IsNullable As Boolean _
     _
       Implements IDataParameter.IsNullable

*Syntax: C#*

     public bool IsNullable {get; set;}

*Implements*

IDataParameter.IsNullable

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-isunsigned,  Next: connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype,  Prev: connector-net-ref-mysqlclient-mysqlparameter-isnullable,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.75 IsUnsigned Property
.............................

*Syntax: Visual Basic*

     Public Property IsUnsigned As Boolean

*Syntax: C#*

     public bool IsUnsigned {get; set;}

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype,  Next: connector-net-ref-mysqlclient-mysqlparameter-parametername,  Prev: connector-net-ref-mysqlclient-mysqlparameter-isunsigned,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.76 `MySqlDbType' Property
................................

Gets or sets the MySqlDbType of the parameter.

*Syntax: Visual Basic*

     Public Property MySqlDbType As MySqlDbType

*Syntax: C#*

     public MySqlDbType MySqlDbType {get; set;}

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-parametername,  Next: connector-net-ref-mysqlclient-mysqlparameter-precision,  Prev: connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.77 ParameterName Property
................................

Gets or sets the name of the MySqlParameter.

*Syntax: Visual Basic*

     NotOverridable Public Property ParameterName As String _
     _
       Implements IDataParameter.ParameterName

*Syntax: C#*

     public string ParameterName {get; set;}

*Implements*

IDataParameter.ParameterName

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-precision,  Next: connector-net-ref-mysqlclient-mysqlparameter-scale,  Prev: connector-net-ref-mysqlclient-mysqlparameter-parametername,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.78 Precision Property
............................

Gets or sets the maximum number of digits used to represent the *Note
Value: connector-net-ref-mysqlclient-mysqlparameter-value.  property.

*Syntax: Visual Basic*

     NotOverridable Public Property Precision As Byte _
     _
       Implements IDbDataParameter.Precision

*Syntax: C#*

     public byte Precision {get; set;}

*Implements*

IDbDataParameter.Precision

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-scale,  Next: connector-net-ref-mysqlclient-mysqlparameter-size,  Prev: connector-net-ref-mysqlclient-mysqlparameter-precision,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.79 Scale Property
........................

Gets or sets the number of decimal places to which *Note Value:
connector-net-ref-mysqlclient-mysqlparameter-value.  is resolved.

*Syntax: Visual Basic*

     NotOverridable Public Property Scale As Byte _
     _
       Implements IDbDataParameter.Scale

*Syntax: C#*

     public byte Scale {get; set;}

*Implements*

IDbDataParameter.Scale

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-size,  Next: connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn,  Prev: connector-net-ref-mysqlclient-mysqlparameter-scale,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.80 Size Property
.......................

Gets or sets the maximum size, in bytes, of the data within the column.

*Syntax: Visual Basic*

     NotOverridable Public Property Size As Integer _
     _
       Implements IDbDataParameter.Size

*Syntax: C#*

     public int Size {get; set;}

*Implements*

IDbDataParameter.Size

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn,  Next: connector-net-ref-mysqlclient-mysqlparameter-sourceversion,  Prev: connector-net-ref-mysqlclient-mysqlparameter-size,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.81 SourceColumn Property
...............................

Gets or sets the name of the source column that is mapped to the
DataSetand used for loading or returning the *Note Value:
connector-net-ref-mysqlclient-mysqlparameter-value .

*Syntax: Visual Basic*

     NotOverridable Public Property SourceColumn As String _
     _
       Implements IDataParameter.SourceColumn

*Syntax: C#*

     public string SourceColumn {get; set;}

*Implements*

IDataParameter.SourceColumn

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-sourceversion,  Next: connector-net-ref-mysqlclient-mysqlparameter-tostring,  Prev: connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.82 SourceVersion Property
................................

Gets or sets the DataRowVersionto use when loading *Note Value:
connector-net-ref-mysqlclient-mysqlparameter-value .

*Syntax: Visual Basic*

     NotOverridable Public Property SourceVersion As DataRowVersion _
     _
       Implements IDataParameter.SourceVersion

*Syntax: C#*

     public System.Data.DataRowVersion SourceVersion {get; set;}

*Implements*

IDataParameter.SourceVersion

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-tostring,  Prev: connector-net-ref-mysqlclient-mysqlparameter-sourceversion,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

20.2.4.83 `MySqlParameter.ToString' Method
..........................................

Overridden. Gets a string containing the *Note ParameterName:
connector-net-ref-mysqlclient-mysqlparameter-parametername .

*Syntax: Visual Basic*

     Overrides Public Function ToString() As String

*Syntax: C#*

     public override string ToString();

*Return Value*

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-item1,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-item2,  Prev: connector-net-ref-mysqlclient-mysqlparameter,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionitem

20.2.4.84 Item Property (Int32)
...............................

Gets the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  at the specified index.

*Syntax: Visual Basic*

     Overloads Public Default Property Item( _
        ByVal index As Integer _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter this[
     intindex
     ] {get; set;}

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Item Overload List:
connector-net-ref-mysqlclient-mysqlparametercollectionitem.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-item2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-item1,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionitem

20.2.4.85 Item Property (String)
................................

Gets the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  with the specified name.

*Syntax: Visual Basic*

     Overloads Public Default Property Item( _
        ByVal name As String _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter this[
     stringname
     ] {get; set;}

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Item Overload List:
connector-net-ref-mysqlclient-mysqlparametercollectionitem.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-clear,  Prev: connector-net-ref-mysqlclient-mysqlparametercollectionitem,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.86 Add Method
....................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-2::  `MySqlParameterCollection.Add' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-1::  `MySqlParameterCollection.Add' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-4::  `MySqlParameterCollection.Add' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-5::  `MySqlParameterCollection.Add' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-6::  `MySqlParameterCollection.Add' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-3::  `MySqlParameterCollection.Add' Method

Adds the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection .

*Overload List*

Adds the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection .

   * *Note public MySqlParameter Add(MySqlParameter);:
     connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-2.

Adds the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection .

   * *Note public int Add(object);:
     connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-1.

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  given the
parameter name and the data type.

   * *Note public MySqlParameter Add(string:
     (MySqlDbType);)connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-4.

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  with the
parameter name, the data type, and the column length.

   * *Note public MySqlParameter Add(string:
     (MySqlDbType)connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-5.

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  with the
parameter name, the data type, the column length, and the source column
name.

   * *Note public MySqlParameter Add(string:
     (MySqlDbType)connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-6.string);

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  given the
specified parameter name and value.

   * *Note public MySqlParameter Add(string:
     (object);)connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-3.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-2,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-1,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

20.2.4.87 `MySqlParameterCollection.Add' Method
...............................................

Adds the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection .

*Syntax: Visual Basic*

     Overloads Public Function Add( _
        ByVal value As MySqlParameter _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter Add(
     MySqlParametervalue
     );

*Parameters*

   * `value': The *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  to add to the
     collection.

*Return Value*

The newly added *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-1,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-4,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-2,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

20.2.4.88 `MySqlParameterCollection.Add' Method
...............................................

Adds the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection .

*Syntax: Visual Basic*

     NotOverridable Overloads Public Function Add( _
        ByVal value As Object _
     ) As Integer _
     _
       Implements IList.Add

*Syntax: C#*

     public int Add(
     objectvalue
     );

*Parameters*

   * `value': The *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  to add to the
     collection.

*Return Value*

The index of the new *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*Implements*

IList.Add

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-4,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-5,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-1,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

20.2.4.89 `MySqlParameterCollection.Add' Method
...............................................

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  given the
parameter name and the data type.

*Syntax: Visual Basic*

     Overloads Public Function Add( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter Add(
     stringparameterName,
     MySqlDbTypedbType
     );

*Parameters*

   * `parameterName': The name of the parameter.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

*Return Value*

The newly added *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-5,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-6,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-4,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

20.2.4.90 `MySqlParameterCollection.Add' Method
...............................................

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  with the
parameter name, the data type, and the column length.

*Syntax: Visual Basic*

     Overloads Public Function Add( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType, _
        ByVal size As Integer _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter Add(
     stringparameterName,
     MySqlDbTypedbType,
     intsize
     );

*Parameters*

   * `parameterName': The name of the parameter.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

   * `size': The length of the column.

*Return Value*

The newly added *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-6,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-3,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-5,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

20.2.4.91 `MySqlParameterCollection.Add' Method
...............................................

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  with the
parameter name, the data type, the column length, and the source column
name.

*Syntax: Visual Basic*

     Overloads Public Function Add( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType, _
        ByVal size As Integer, _
        ByVal sourceColumn As String _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter Add(
     stringparameterName,
     MySqlDbTypedbType,
     intsize,
     stringsourceColumn
     );

*Parameters*

   * `parameterName': The name of the parameter.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

   * `size': The length of the column.

   * `sourceColumn': The name of the source column.

*Return Value*

The newly added *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-3,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-6,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

20.2.4.92 `MySqlParameterCollection.Add' Method
...............................................

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  given the
specified parameter name and value.

*Syntax: Visual Basic*

     Overloads Public Function Add( _
        ByVal parameterName As String, _
        ByVal value As Object _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter Add(
     stringparameterName,
     objectvalue
     );

*Parameters*

   * `parameterName': The name of the parameter.

   * `value': The *Note Value:
     connector-net-ref-mysqlclient-mysqlparameter-value.  of the *Note
     MySqlParameter: connector-net-ref-mysqlclient-mysqlparameter.  to
     add to the collection.

*Return Value*

The newly added *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-clear,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.93 `MySqlParameterCollection.Clear' Method
.................................................

Removes all items from the collection.

*Syntax: Visual Basic*

     NotOverridable Public Sub Clear() _
     _
       Implements IList.Clear

*Syntax: C#*

     public void Clear();

*Implements*

IList.Clear

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-copyto,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-clear,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.94 Contains Method
.........................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-1::  `MySqlParameterCollection.Contains' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-2::  `MySqlParameterCollection.Contains' Method

Gets a value indicating whether a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  exists in the collection.

*Overload List*

Gets a value indicating whether a MySqlParameter exists in the
collection.

   * *Note public bool Contains(object);:
     connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-1.

Gets a value indicating whether a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  with the specified
parameter name exists in the collection.

   * *Note public bool Contains(string);:
     connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-2.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-1,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads

20.2.4.95 `MySqlParameterCollection.Contains' Method
....................................................

Gets a value indicating whether a MySqlParameter exists in the
collection.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Function Contains( _
        ByVal value As Object _
     ) As Boolean _
     _
       Implements IList.Contains

*Syntax: C#*

     public bool Contains(
     objectvalue
     );

*Parameters*

   * `value': The value of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  object to find.

*Return Value*

true if the collection contains the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object; otherwise, false.

*Implements*

IList.Contains

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Contains Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-1,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads

20.2.4.96 `MySqlParameterCollection.Contains' Method
....................................................

Gets a value indicating whether a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  with the specified
parameter name exists in the collection.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Function Contains( _
        ByVal name As String _
     ) As Boolean _
     _
       Implements IDataParameterCollection.Contains

*Syntax: C#*

     public bool Contains(
     stringname
     );

*Parameters*

   * `name': The name of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  object to find.

*Return Value*

true if the collection contains the parameter; otherwise, false.

*Implements*

IDataParameterCollection.Contains

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Contains Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-copyto,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.97 `MySqlParameterCollection.CopyTo' Method
..................................................

Copies MySqlParameter objects from the MySqlParameterCollection to the
specified array.

*Syntax: Visual Basic*

     NotOverridable Public Sub CopyTo( _
        ByVal array As Array, _
        ByVal index As Integer _
     ) _
     _
       Implements ICollection.CopyTo

*Syntax: C#*

     public void CopyTo(
     Arrayarray,
     intindex
     );

*Parameters*

   * `array':

   * `index':

*Implements*

ICollection.CopyTo

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-insert,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-copyto,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.98 IndexOf Method
........................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-1::  `MySqlParameterCollection.IndexOf' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-2::  `MySqlParameterCollection.IndexOf' Method

Gets the location of a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection.

*Overload List*

Gets the location of a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection.

   * *Note public int IndexOf(object);:
     connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-1.

Gets the location of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection with a
specific parameter name.

   * *Note public int IndexOf(string);:
     connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-2.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-1,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads

20.2.4.99 `MySqlParameterCollection.IndexOf' Method
...................................................

Gets the location of a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Function IndexOf( _
        ByVal value As Object _
     ) As Integer _
     _
       Implements IList.IndexOf

*Syntax: C#*

     public int IndexOf(
     objectvalue
     );

*Parameters*

   * `value': The *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  object to locate.

*Return Value*

The zero-based location of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection.

*Implements*

IList.IndexOf

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.IndexOf Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-1,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads

20.2.4.100 `MySqlParameterCollection.IndexOf' Method
....................................................

Gets the location of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection with a
specific parameter name.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Function IndexOf( _
        ByVal parameterName As String _
     ) As Integer _
     _
       Implements IDataParameterCollection.IndexOf

*Syntax: C#*

     public int IndexOf(
     stringparameterName
     );

*Parameters*

   * `parameterName': The name of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  object to retrieve.

*Return Value*

The zero-based location of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection.

*Implements*

IDataParameterCollection.IndexOf

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.IndexOf Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-insert,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-remove,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.101 `MySqlParameterCollection.Insert' Method
...................................................

Inserts a MySqlParameter into the collection at the specified index.

*Syntax: Visual Basic*

     NotOverridable Public Sub Insert( _
        ByVal index As Integer, _
        ByVal value As Object _
     ) _
     _
       Implements IList.Insert

*Syntax: C#*

     public void Insert(
     intindex,
     objectvalue
     );

*Parameters*

   * `index':

   * `value':

*Implements*

IList.Insert

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-remove,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-insert,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.102 `MySqlParameterCollection.Remove' Method
...................................................

Removes the specified MySqlParameter from the collection.

*Syntax: Visual Basic*

     NotOverridable Public Sub Remove( _
        ByVal value As Object _
     ) _
     _
       Implements IList.Remove

*Syntax: C#*

     public void Remove(
     objectvalue
     );

*Parameters*

   * `value':

*Implements*

IList.Remove

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-remove,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

20.2.4.103 RemoveAt Method
..........................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-1::  `MySqlParameterCollection.RemoveAt' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-2::  `MySqlParameterCollection.RemoveAt' Method

Removes the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  from the collection.

*Overload List*

Removes the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  from the collection
using a specific index.

   * *Note public void RemoveAt(int);:
     connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-1.

Removes the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  from the collection
using the parameter name.

   * *Note public void RemoveAt(string);:
     connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-2.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-1,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads

20.2.4.104 `MySqlParameterCollection.RemoveAt' Method
.....................................................

Removes the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  from the collection
using a specific index.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Sub RemoveAt( _
        ByVal index As Integer _
     ) _
     _
       Implements IList.RemoveAt

*Syntax: C#*

     public void RemoveAt(
     intindex
     );

*Parameters*

   * `index': The zero-based index of the parameter.

*Implements*

IList.RemoveAt

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.RemoveAt Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-1,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads

20.2.4.105 `MySqlParameterCollection.RemoveAt' Method
.....................................................

Removes the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  from the collection
using the parameter name.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Sub RemoveAt( _
        ByVal name As String _
     ) _
     _
       Implements IDataParameterCollection.RemoveAt

*Syntax: C#*

     public void RemoveAt(
     stringname
     );

*Parameters*

   * `name': The name of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  object to retrieve.

*Implements*

IDataParameterCollection.RemoveAt

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.RemoveAt Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-transaction,  Next: connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource,  Prev: connector-net-ref-mysqlclient-mysqlcommand-parameters,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.106 Transaction Property
...............................

*Syntax: Visual Basic*

     Public Property Transaction As MySqlTransaction

*Syntax: C#*

     public MySqlTransaction Transaction {get; set;}

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource,  Next: connector-net-ref-mysqlclient-mysqlcommand-cancel,  Prev: connector-net-ref-mysqlclient-mysqlcommand-transaction,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.107 UpdatedRowSource Property
....................................

*Syntax: Visual Basic*

     NotOverridable Public Property UpdatedRowSource As UpdateRowSource _
     _
       Implements IDbCommand.UpdatedRowSource

*Syntax: C#*

     public System.Data.UpdateRowSource UpdatedRowSource {get; set;}

*Implements*

IDbCommand.UpdatedRowSource

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-cancel,  Next: connector-net-ref-mysqlclient-mysqlcommand-createparameter,  Prev: connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.108 `MySqlCommand.Cancel' Method
.......................................

Attempts to cancel the execution of a MySqlCommand. This operation is
not supported.

*Syntax: Visual Basic*

     NotOverridable Public Sub Cancel() _
     _
       Implements IDbCommand.Cancel

*Syntax: C#*

     public void Cancel();

*Implements*

IDbCommand.Cancel

*Remarks*

Cancelling an executing command is currently not supported on any
version of MySQL.

*Exceptions*

*Exception Type*                     *Condition*
NotSupportedException                This operation is not supported.

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-createparameter,  Next: connector-net-ref-mysqlclient-mysqlcommand-executenonquery,  Prev: connector-net-ref-mysqlclient-mysqlcommand-cancel,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.109 `MySqlCommand.CreateParameter' Method
................................................

Creates a new instance of a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*Syntax: Visual Basic*

     Public Function CreateParameter() As MySqlParameter

*Syntax: C#*

     public MySqlParameter CreateParameter();

*Return Value*

A *Note MySqlParameter: connector-net-ref-mysqlclient-mysqlparameter.
object.

*Remarks*

This method is a strongly-typed version of CreateParameter.

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-executenonquery,  Next: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads,  Prev: connector-net-ref-mysqlclient-mysqlcommand-createparameter,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.110 `MySqlCommand.ExecuteNonQuery' Method
................................................

*Syntax: Visual Basic*

     NotOverridable Public Function ExecuteNonQuery() As Integer _
     _
       Implements IDbCommand.ExecuteNonQuery

*Syntax: C#*

     public int ExecuteNonQuery();

*Implements*

IDbCommand.ExecuteNonQuery

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads,  Next: connector-net-ref-mysqlclient-mysqlcommand-executescalar,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executenonquery,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.111 ExecuteReader Method
...............................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1::  `MySqlCommand.ExecuteReader' Method
* connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-2::  `MySqlCommand.ExecuteReader' Method

*Overload List*

   * *Note public MySqlDataReader ExecuteReader();:
     connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1.

   * *Note public MySqlDataReader ExecuteReader(CommandBehavior);:
     connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-2.

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1,  Next: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads,  Up: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads

20.2.4.112 `MySqlCommand.ExecuteReader' Method
..............................................

* Menu:

* connector-net-ref-mysqlclient-mysqldatareader::  `MySqlDataReader' Class

*Syntax: Visual Basic*

     Overloads Public Function ExecuteReader() As MySqlDataReader

*Syntax: C#*

     public MySqlDataReader ExecuteReader();

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand.ExecuteReader Overload List:
connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1,  Up: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1

20.2.4.113 `MySqlDataReader' Class
..................................

* Menu:

* connector-net-ref-mysqlclient-mysqldatareadermembers::  `MySqlDataReader' Members

Provides a means of reading a forward-only stream of rows from a MySQL
database. This class cannot be inherited.

For a list of all members of this type, see *Note MySqlDataReader
Members: connector-net-ref-mysqlclient-mysqldatareadermembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlDataReader_
       Inherits MarshalByRefObject_
       Implements IEnumerable, IDataReader, IDisposable, IDataRecord

*Syntax: C#*

     public sealed class MySqlDataReader : MarshalByRefObject, IEnumerable, IDataReader, IDisposable, IDataRecord

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlDataReader Members:
connector-net-ref-mysqlclient-mysqldatareadermembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareadermembers,  Prev: connector-net-ref-mysqlclient-mysqldatareader,  Up: connector-net-ref-mysqlclient-mysqldatareader

20.2.4.114 `MySqlDataReader' Members
....................................

* Menu:

* connector-net-ref-mysqlclient-mysqldatareader-depth::  Depth Property
* connector-net-ref-mysqlclient-mysqldatareader-fieldcount::  FieldCount Property
* connector-net-ref-mysqlclient-mysqldatareader-hasrows::  HasRows Property
* connector-net-ref-mysqlclient-mysqldatareader-isclosed::  IsClosed Property
* connector-net-ref-mysqlclient-mysqldatareaderitem::  Item Property
* connector-net-ref-mysqlclient-mysqldatareader-recordsaffected::  RecordsAffected Property
* connector-net-ref-mysqlclient-mysqldatareader-close::  `MySqlDataReader.Close' Method
* connector-net-ref-mysqlclient-mysqldatareader-getboolean::  `MySqlDataReader.GetBoolean' Method
* connector-net-ref-mysqlclient-mysqldatareader-getbyte::  `MySqlDataReader.GetByte' Method
* connector-net-ref-mysqlclient-mysqldatareader-getbytes::  `MySqlDataReader.GetBytes' Method
* connector-net-ref-mysqlclient-mysqldatareader-getchar::  `MySqlDataReader.GetChar' Method
* connector-net-ref-mysqlclient-mysqldatareader-getchars::  `MySqlDataReader.GetChars' Method
* connector-net-ref-mysqlclient-mysqldatareader-getdatatypename::  `MySqlDataReader.GetDataTypeName' Method
* connector-net-ref-mysqlclient-mysqldatareader-getdatetime::  `MySqlDataReader.GetDateTime' Method
* connector-net-ref-mysqlclient-mysqldatareader-getdecimal::  `MySqlDataReader.GetDecimal' Method
* connector-net-ref-mysqlclient-mysqldatareader-getdouble::  `MySqlDataReader.GetDouble' Method
* connector-net-ref-mysqlclient-mysqldatareader-getfieldtype::  `MySqlDataReader.GetFieldType' Method
* connector-net-ref-mysqlclient-mysqldatareader-getfloat::  `MySqlDataReader.GetFloat' Method
* connector-net-ref-mysqlclient-mysqldatareader-getguid::  `MySqlDataReader.GetGuid' Method
* connector-net-ref-mysqlclient-mysqldatareader-getint16::  `MySqlDataReader.GetInt16' Method
* connector-net-ref-mysqlclient-mysqldatareader-getint32::  `MySqlDataReader.GetInt32' Method
* connector-net-ref-mysqlclient-mysqldatareader-getint64::  `MySqlDataReader.GetInt64' Method
* connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime::  `MySqlDataReader.GetMySqlDateTime' Method
* connector-net-ref-mysqlclient-mysqldatareader-getname::  `MySqlDataReader.GetName' Method
* connector-net-ref-mysqlclient-mysqldatareader-getordinal::  `MySqlDataReader.GetOrdinal' Method
* connector-net-ref-mysqlclient-mysqldatareader-getschematable::  `MySqlDataReader.GetSchemaTable' Method
* connector-net-ref-mysqlclient-mysqldatareader-getstring::  `MySqlDataReader.GetString' Method
* connector-net-ref-mysqlclient-mysqldatareader-gettimespan::  `MySqlDataReader.GetTimeSpan' Method
* connector-net-ref-mysqlclient-mysqldatareader-getuint16::  `MySqlDataReader.GetUInt16' Method
* connector-net-ref-mysqlclient-mysqldatareader-getuint32::  `MySqlDataReader.GetUInt32' Method
* connector-net-ref-mysqlclient-mysqldatareader-getuint64::  `MySqlDataReader.GetUInt64' Method
* connector-net-ref-mysqlclient-mysqldatareader-getvalue::  `MySqlDataReader.GetValue' Method
* connector-net-ref-mysqlclient-mysqldatareader-getvalues::  `MySqlDataReader.GetValues' Method
* connector-net-ref-mysqlclient-mysqldatareader-isdbnull::  `MySqlDataReader.IsDBNull' Method
* connector-net-ref-mysqlclient-mysqldatareader-nextresult::  `MySqlDataReader.NextResult' Method
* connector-net-ref-mysqlclient-mysqldatareader-read::  `MySqlDataReader.Read' Method

*Note MySqlDataReader overview:
connector-net-ref-mysqlclient-mysqldatareader.

*Public Instance Properties*

*Note Depth:                         Gets a value indicating the depth
connector-net-ref-mysqlclient-mysqldatareader-depth.of nesting for the current row. This
                                     method is not supported currently
                                     and always returns 0.
*Note FieldCount:                    Gets the number of columns in the
connector-net-ref-mysqlclient-mysqldatareader-fieldcount.current row.
*Note HasRows:                       Gets a value indicating whether the
connector-net-ref-mysqlclient-mysqldatareader-hasrows.MySqlDataReader contains one or more
                                     rows.
*Note IsClosed:                      Gets a value indicating whether the
connector-net-ref-mysqlclient-mysqldatareader-isclosed.data reader is closed.
*Note Item:                          Overloaded. Overloaded. Gets the
connector-net-ref-mysqlclient-mysqldatareaderitem.value of a column in its native
                                     format.  In C#, this property is
                                     the indexer for the MySqlDataReader
                                     class.
*Note RecordsAffected:               Gets the number of rows changed,
connector-net-ref-mysqlclient-mysqldatareader-recordsaffected.inserted, or deleted by execution of
                                     the SQL statement.

*Public Instance Methods*

*Note Close:                         Closes the MySqlDataReader object.
connector-net-ref-mysqlclient-mysqldatareader-close.
CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
*Note GetBoolean:                    Gets the value of the specified
connector-net-ref-mysqlclient-mysqldatareader-getboolean.column as a Boolean.
*Note GetByte:                       Gets the value of the specified
connector-net-ref-mysqlclient-mysqldatareader-getbyte.column as a byte.
*Note GetBytes:                      Reads a stream of bytes from the
connector-net-ref-mysqlclient-mysqldatareader-getbytes.specified column offset into the
                                     buffer an array starting at the
                                     given buffer offset.
*Note GetChar:                       Gets the value of the specified
connector-net-ref-mysqlclient-mysqldatareader-getchar.column as a single character.
*Note GetChars:                      Reads a stream of characters from
connector-net-ref-mysqlclient-mysqldatareader-getchars.the specified column offset into the
                                     buffer as an array starting at the
                                     given buffer offset.
*Note GetDataTypeName:               Gets the name of the source data
connector-net-ref-mysqlclient-mysqldatareader-getdatatypename.type.
*Note GetDateTime:                   
connector-net-ref-mysqlclient-mysqldatareader-getdatetime.
*Note GetDecimal:                    
connector-net-ref-mysqlclient-mysqldatareader-getdecimal.
*Note GetDouble:                     
connector-net-ref-mysqlclient-mysqldatareader-getdouble.
*Note GetFieldType:                  Gets the Type that is the data type
connector-net-ref-mysqlclient-mysqldatareader-getfieldtype.of the object.
*Note GetFloat:                      
connector-net-ref-mysqlclient-mysqldatareader-getfloat.
*Note GetGuid:                       
connector-net-ref-mysqlclient-mysqldatareader-getguid.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
*Note GetInt16:                      
connector-net-ref-mysqlclient-mysqldatareader-getint16.
*Note GetInt32:                      
connector-net-ref-mysqlclient-mysqldatareader-getint32.
*Note GetInt64:                      
connector-net-ref-mysqlclient-mysqldatareader-getint64.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
*Note GetMySqlDateTime:              
connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime.
*Note GetName:                       Gets the name of the specified
connector-net-ref-mysqlclient-mysqldatareader-getname.column.
*Note GetOrdinal:                    Gets the column ordinal, given the
connector-net-ref-mysqlclient-mysqldatareader-getordinal.name of the column.
*Note GetSchemaTable:                Returns a DataTable that describes
connector-net-ref-mysqlclient-mysqldatareader-getschematable.the column metadata of the
                                     MySqlDataReader.
*Note GetString:                     
connector-net-ref-mysqlclient-mysqldatareader-getstring.
*Note GetTimeSpan:                   
connector-net-ref-mysqlclient-mysqldatareader-gettimespan.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note GetUInt16:                     
connector-net-ref-mysqlclient-mysqldatareader-getuint16.
*Note GetUInt32:                     
connector-net-ref-mysqlclient-mysqldatareader-getuint32.
*Note GetUInt64:                     
connector-net-ref-mysqlclient-mysqldatareader-getuint64.
*Note GetValue:                      Gets the value of the specified
connector-net-ref-mysqlclient-mysqldatareader-getvalue.column in its native format.
*Note GetValues:                     Gets all attribute columns in the
connector-net-ref-mysqlclient-mysqldatareader-getvalues.collection for the current row.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note IsDBNull:                      Gets a value indicating whether the
connector-net-ref-mysqlclient-mysqldatareader-isdbnull.column contains non-existent or
                                     missing values.
*Note NextResult:                    Advances the data reader to the
connector-net-ref-mysqlclient-mysqldatareader-nextresult.next result, when reading the
                                     results of batch SQL statements.
*Note Read:                          Advances the MySqlDataReader to the
connector-net-ref-mysqlclient-mysqldatareader-read.next record.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-depth,  Next: connector-net-ref-mysqlclient-mysqldatareader-fieldcount,  Prev: connector-net-ref-mysqlclient-mysqldatareadermembers,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.115 Depth Property
.........................

Gets a value indicating the depth of nesting for the current row. This
method is not supported currently and always returns 0.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property Depth As Integer _
     _
       Implements IDataReader.Depth

*Syntax: C#*

     public int Depth {get;}

*Implements*

IDataReader.Depth

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-fieldcount,  Next: connector-net-ref-mysqlclient-mysqldatareader-hasrows,  Prev: connector-net-ref-mysqlclient-mysqldatareader-depth,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.116 FieldCount Property
..............................

Gets the number of columns in the current row.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property FieldCount As Integer _
     _
       Implements IDataRecord.FieldCount

*Syntax: C#*

     public int FieldCount {get;}

*Implements*

IDataRecord.FieldCount

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-hasrows,  Next: connector-net-ref-mysqlclient-mysqldatareader-isclosed,  Prev: connector-net-ref-mysqlclient-mysqldatareader-fieldcount,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.117 HasRows Property
...........................

Gets a value indicating whether the MySqlDataReader contains one or
more rows.

*Syntax: Visual Basic*

     Public ReadOnly Property HasRows As Boolean

*Syntax: C#*

     public bool HasRows {get;}

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-isclosed,  Next: connector-net-ref-mysqlclient-mysqldatareaderitem,  Prev: connector-net-ref-mysqlclient-mysqldatareader-hasrows,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.118 IsClosed Property
............................

Gets a value indicating whether the data reader is closed.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property IsClosed As Boolean _
     _
       Implements IDataReader.IsClosed

*Syntax: C#*

     public bool IsClosed {get;}

*Implements*

IDataReader.IsClosed

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareaderitem,  Next: connector-net-ref-mysqlclient-mysqldatareader-recordsaffected,  Prev: connector-net-ref-mysqlclient-mysqldatareader-isclosed,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.119 Item Property
........................

* Menu:

* connector-net-ref-mysqlclient-mysqldatareader-item1::  Item Property (Int32)
* connector-net-ref-mysqlclient-mysqldatareader-item2::  Item Property (String)

Overloaded. Gets the value of a column in its native format. In C#,
this property is the indexer for the MySqlDataReader class.

*Overload List*

Overloaded. Gets the value of a column in its native format. In C#,
this property is the indexer for the MySqlDataReader class.

   * *Note public object this[int] {get;}:
     connector-net-ref-mysqlclient-mysqldatareader-item1.

Gets the value of a column in its native format.  In C#, this property
is the indexer for the MySqlDataReader class.

   * *Note public object this[string] {get;}:
     connector-net-ref-mysqlclient-mysqldatareader-item2.

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-item1,  Next: connector-net-ref-mysqlclient-mysqldatareader-item2,  Prev: connector-net-ref-mysqlclient-mysqldatareaderitem,  Up: connector-net-ref-mysqlclient-mysqldatareaderitem

20.2.4.120 Item Property (Int32)
................................

Overloaded. Gets the value of a column in its native format. In C#,
this property is the indexer for the MySqlDataReader class.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Default ReadOnly Property Item( _
        ByVal i As Integer _
     ) _
     _
       Implements IDataRecord.Item As Object _
     _
       Implements IDataRecord.Item

*Syntax: C#*

     public object this[
     inti
     ] {get;}

*Implements*

IDataRecord.Item

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataReader.Item Overload List:
connector-net-ref-mysqlclient-mysqldatareaderitem.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-item2,  Prev: connector-net-ref-mysqlclient-mysqldatareader-item1,  Up: connector-net-ref-mysqlclient-mysqldatareaderitem

20.2.4.121 Item Property (String)
.................................

Gets the value of a column in its native format.  In C#, this property
is the indexer for the MySqlDataReader class.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Default ReadOnly Property Item( _
        ByVal name As String _
     ) _
     _
       Implements IDataRecord.Item As Object _
     _
       Implements IDataRecord.Item

*Syntax: C#*

     public object this[
     stringname
     ] {get;}

*Implements*

IDataRecord.Item

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataReader.Item Overload List:
connector-net-ref-mysqlclient-mysqldatareaderitem.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-recordsaffected,  Next: connector-net-ref-mysqlclient-mysqldatareader-close,  Prev: connector-net-ref-mysqlclient-mysqldatareaderitem,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.122 RecordsAffected Property
...................................

Gets the number of rows changed, inserted, or deleted by execution of
the SQL statement.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property RecordsAffected As Integer _
     _
       Implements IDataReader.RecordsAffected

*Syntax: C#*

     public int RecordsAffected {get;}

*Implements*

IDataReader.RecordsAffected

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-close,  Next: connector-net-ref-mysqlclient-mysqldatareader-getboolean,  Prev: connector-net-ref-mysqlclient-mysqldatareader-recordsaffected,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.123 `MySqlDataReader.Close' Method
.........................................

Closes the MySqlDataReader object.

*Syntax: Visual Basic*

     NotOverridable Public Sub Close() _
     _
       Implements IDataReader.Close

*Syntax: C#*

     public void Close();

*Implements*

IDataReader.Close

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getboolean,  Next: connector-net-ref-mysqlclient-mysqldatareader-getbyte,  Prev: connector-net-ref-mysqlclient-mysqldatareader-close,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.124 `MySqlDataReader.GetBoolean' Method
..............................................

Gets the value of the specified column as a Boolean.

*Syntax: Visual Basic*

     NotOverridable Public Function GetBoolean( _
        ByVal i As Integer _
     ) As Boolean _
     _
       Implements IDataRecord.GetBoolean

*Syntax: C#*

     public bool GetBoolean(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetBoolean

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getbyte,  Next: connector-net-ref-mysqlclient-mysqldatareader-getbytes,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getboolean,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.125 `MySqlDataReader.GetByte' Method
...........................................

Gets the value of the specified column as a byte.

*Syntax: Visual Basic*

     NotOverridable Public Function GetByte( _
        ByVal i As Integer _
     ) As Byte _
     _
       Implements IDataRecord.GetByte

*Syntax: C#*

     public byte GetByte(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetByte

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getbytes,  Next: connector-net-ref-mysqlclient-mysqldatareader-getchar,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getbyte,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.126 `MySqlDataReader.GetBytes' Method
............................................

Reads a stream of bytes from the specified column offset into the
buffer an array starting at the given buffer offset.

*Syntax: Visual Basic*

     NotOverridable Public Function GetBytes( _
        ByVal i As Integer, _
        ByVal dataIndex As Long, _
        ByVal buffer As Byte(), _
        ByVal bufferIndex As Integer, _
        ByVal length As Integer _
     ) As Long _
     _
       Implements IDataRecord.GetBytes

*Syntax: C#*

     public long GetBytes(
     inti,
     longdataIndex,
     byte[]buffer,
     intbufferIndex,
     intlength
     );

*Parameters*

   * `i': The zero-based column ordinal.

   * `dataIndex': The index within the field from which to begin the
     read operation.

   * `buffer': The buffer into which to read the stream of bytes.

   * `bufferIndex': The index for buffer to begin the read operation.

   * `length': The maximum length to copy into the buffer.

*Return Value*

The actual number of bytes read.

*Implements*

IDataRecord.GetBytes

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getchar,  Next: connector-net-ref-mysqlclient-mysqldatareader-getchars,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getbytes,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.127 `MySqlDataReader.GetChar' Method
...........................................

Gets the value of the specified column as a single character.

*Syntax: Visual Basic*

     NotOverridable Public Function GetChar( _
        ByVal i As Integer _
     ) As Char _
     _
       Implements IDataRecord.GetChar

*Syntax: C#*

     public char GetChar(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetChar

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getchars,  Next: connector-net-ref-mysqlclient-mysqldatareader-getdatatypename,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getchar,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.128 `MySqlDataReader.GetChars' Method
............................................

Reads a stream of characters from the specified column offset into the
buffer as an array starting at the given buffer offset.

*Syntax: Visual Basic*

     NotOverridable Public Function GetChars( _
        ByVal i As Integer, _
        ByVal fieldOffset As Long, _
        ByVal buffer As Char(), _
        ByVal bufferoffset As Integer, _
        ByVal length As Integer _
     ) As Long _
     _
       Implements IDataRecord.GetChars

*Syntax: C#*

     public long GetChars(
     inti,
     longfieldOffset,
     char[]buffer,
     intbufferoffset,
     intlength
     );

*Parameters*

   * `i':

   * `fieldOffset':

   * `buffer':

   * `bufferoffset':

   * `length':

*Return Value*

*Implements*

IDataRecord.GetChars

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getdatatypename,  Next: connector-net-ref-mysqlclient-mysqldatareader-getdatetime,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getchars,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.129 `MySqlDataReader.GetDataTypeName' Method
...................................................

Gets the name of the source data type.

*Syntax: Visual Basic*

     NotOverridable Public Function GetDataTypeName( _
        ByVal i As Integer _
     ) As String _
     _
       Implements IDataRecord.GetDataTypeName

*Syntax: C#*

     public string GetDataTypeName(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetDataTypeName

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getdatetime,  Next: connector-net-ref-mysqlclient-mysqldatareader-getdecimal,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getdatatypename,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.130 `MySqlDataReader.GetDateTime' Method
...............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetDateTime( _
        ByVal index As Integer _
     ) As Date _
     _
       Implements IDataRecord.GetDateTime

*Syntax: C#*

     public DateTime GetDateTime(
     intindex
     );

*Implements*

IDataRecord.GetDateTime

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getdecimal,  Next: connector-net-ref-mysqlclient-mysqldatareader-getdouble,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getdatetime,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.131 `MySqlDataReader.GetDecimal' Method
..............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetDecimal( _
        ByVal index As Integer _
     ) As Decimal _
     _
       Implements IDataRecord.GetDecimal

*Syntax: C#*

     public decimal GetDecimal(
     intindex
     );

*Implements*

IDataRecord.GetDecimal

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getdouble,  Next: connector-net-ref-mysqlclient-mysqldatareader-getfieldtype,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getdecimal,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.132 `MySqlDataReader.GetDouble' Method
.............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetDouble( _
        ByVal index As Integer _
     ) As Double _
     _
       Implements IDataRecord.GetDouble

*Syntax: C#*

     public double GetDouble(
     intindex
     );

*Implements*

IDataRecord.GetDouble

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getfieldtype,  Next: connector-net-ref-mysqlclient-mysqldatareader-getfloat,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getdouble,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.133 `MySqlDataReader.GetFieldType' Method
................................................

Gets the Type that is the data type of the object.

*Syntax: Visual Basic*

     NotOverridable Public Function GetFieldType( _
        ByVal i As Integer _
     ) As Type _
     _
       Implements IDataRecord.GetFieldType

*Syntax: C#*

     public Type GetFieldType(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetFieldType

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getfloat,  Next: connector-net-ref-mysqlclient-mysqldatareader-getguid,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getfieldtype,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.134 `MySqlDataReader.GetFloat' Method
............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetFloat( _
        ByVal index As Integer _
     ) As Single _
     _
       Implements IDataRecord.GetFloat

*Syntax: C#*

     public float GetFloat(
     intindex
     );

*Implements*

IDataRecord.GetFloat

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getguid,  Next: connector-net-ref-mysqlclient-mysqldatareader-getint16,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getfloat,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.135 `MySqlDataReader.GetGuid' Method
...........................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetGuid( _
        ByVal index As Integer _
     ) As Guid _
     _
       Implements IDataRecord.GetGuid

*Syntax: C#*

     public Guid GetGuid(
     intindex
     );

*Implements*

IDataRecord.GetGuid

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getint16,  Next: connector-net-ref-mysqlclient-mysqldatareader-getint32,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getguid,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.136 `MySqlDataReader.GetInt16' Method
............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetInt16( _
        ByVal index As Integer _
     ) As Short _
     _
       Implements IDataRecord.GetInt16

*Syntax: C#*

     public short GetInt16(
     intindex
     );

*Implements*

IDataRecord.GetInt16

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getint32,  Next: connector-net-ref-mysqlclient-mysqldatareader-getint64,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getint16,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.137 `MySqlDataReader.GetInt32' Method
............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetInt32( _
        ByVal index As Integer _
     ) As Integer _
     _
       Implements IDataRecord.GetInt32

*Syntax: C#*

     public int GetInt32(
     intindex
     );

*Implements*

IDataRecord.GetInt32

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getint64,  Next: connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getint32,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.138 `MySqlDataReader.GetInt64' Method
............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetInt64( _
        ByVal index As Integer _
     ) As Long _
     _
       Implements IDataRecord.GetInt64

*Syntax: C#*

     public long GetInt64(
     intindex
     );

*Implements*

IDataRecord.GetInt64

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime,  Next: connector-net-ref-mysqlclient-mysqldatareader-getname,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getint64,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.139 `MySqlDataReader.GetMySqlDateTime' Method
....................................................

*Syntax: Visual Basic*

     Public Function GetMySqlDateTime( _
        ByVal index As Integer _
     ) As MySqlDateTime

*Syntax: C#*

     public MySqlDateTime GetMySqlDateTime(
     intindex
     );

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getname,  Next: connector-net-ref-mysqlclient-mysqldatareader-getordinal,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.140 `MySqlDataReader.GetName' Method
...........................................

Gets the name of the specified column.

*Syntax: Visual Basic*

     NotOverridable Public Function GetName( _
        ByVal i As Integer _
     ) As String _
     _
       Implements IDataRecord.GetName

*Syntax: C#*

     public string GetName(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetName

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getordinal,  Next: connector-net-ref-mysqlclient-mysqldatareader-getschematable,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getname,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.141 `MySqlDataReader.GetOrdinal' Method
..............................................

Gets the column ordinal, given the name of the column.

*Syntax: Visual Basic*

     NotOverridable Public Function GetOrdinal( _
        ByVal name As String _
     ) As Integer _
     _
       Implements IDataRecord.GetOrdinal

*Syntax: C#*

     public int GetOrdinal(
     stringname
     );

*Parameters*

   * `name':

*Return Value*

*Implements*

IDataRecord.GetOrdinal

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getschematable,  Next: connector-net-ref-mysqlclient-mysqldatareader-getstring,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getordinal,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.142 `MySqlDataReader.GetSchemaTable' Method
..................................................

Returns a DataTable that describes the column metadata of the
MySqlDataReader.

*Syntax: Visual Basic*

     NotOverridable Public Function GetSchemaTable() As DataTable _
     _
       Implements IDataReader.GetSchemaTable

*Syntax: C#*

     public DataTable GetSchemaTable();

*Return Value*

*Implements*

IDataReader.GetSchemaTable

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getstring,  Next: connector-net-ref-mysqlclient-mysqldatareader-gettimespan,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getschematable,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.143 `MySqlDataReader.GetString' Method
.............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetString( _
        ByVal index As Integer _
     ) As String _
     _
       Implements IDataRecord.GetString

*Syntax: C#*

     public string GetString(
     intindex
     );

*Implements*

IDataRecord.GetString

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-gettimespan,  Next: connector-net-ref-mysqlclient-mysqldatareader-getuint16,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getstring,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.144 `MySqlDataReader.GetTimeSpan' Method
...............................................

*Syntax: Visual Basic*

     Public Function GetTimeSpan( _
        ByVal index As Integer _
     ) As TimeSpan

*Syntax: C#*

     public TimeSpan GetTimeSpan(
     intindex
     );

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getuint16,  Next: connector-net-ref-mysqlclient-mysqldatareader-getuint32,  Prev: connector-net-ref-mysqlclient-mysqldatareader-gettimespan,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.145 `MySqlDataReader.GetUInt16' Method
.............................................

*Syntax: Visual Basic*

     Public Function GetUInt16( _
        ByVal index As Integer _
     ) As UInt16

*Syntax: C#*

     public ushort GetUInt16(
     intindex
     );

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getuint32,  Next: connector-net-ref-mysqlclient-mysqldatareader-getuint64,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getuint16,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.146 `MySqlDataReader.GetUInt32' Method
.............................................

*Syntax: Visual Basic*

     Public Function GetUInt32( _
        ByVal index As Integer _
     ) As UInt32

*Syntax: C#*

     public uint GetUInt32(
     intindex
     );

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getuint64,  Next: connector-net-ref-mysqlclient-mysqldatareader-getvalue,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getuint32,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.147 `MySqlDataReader.GetUInt64' Method
.............................................

*Syntax: Visual Basic*

     Public Function GetUInt64( _
        ByVal index As Integer _
     ) As UInt64

*Syntax: C#*

     public ulong GetUInt64(
     intindex
     );

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getvalue,  Next: connector-net-ref-mysqlclient-mysqldatareader-getvalues,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getuint64,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.148 `MySqlDataReader.GetValue' Method
............................................

Gets the value of the specified column in its native format.

*Syntax: Visual Basic*

     NotOverridable Public Function GetValue( _
        ByVal i As Integer _
     ) As Object _
     _
       Implements IDataRecord.GetValue

*Syntax: C#*

     public object GetValue(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetValue

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getvalues,  Next: connector-net-ref-mysqlclient-mysqldatareader-isdbnull,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getvalue,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.149 `MySqlDataReader.GetValues' Method
.............................................

Gets all attribute columns in the collection for the current row.

*Syntax: Visual Basic*

     NotOverridable Public Function GetValues( _
        ByVal values As Object() _
     ) As Integer _
     _
       Implements IDataRecord.GetValues

*Syntax: C#*

     public int GetValues(
     object[]values
     );

*Parameters*

   * `values':

*Return Value*

*Implements*

IDataRecord.GetValues

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-isdbnull,  Next: connector-net-ref-mysqlclient-mysqldatareader-nextresult,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getvalues,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.150 `MySqlDataReader.IsDBNull' Method
............................................

Gets a value indicating whether the column contains non-existent or
missing values.

*Syntax: Visual Basic*

     NotOverridable Public Function IsDBNull( _
        ByVal i As Integer _
     ) As Boolean _
     _
       Implements IDataRecord.IsDBNull

*Syntax: C#*

     public bool IsDBNull(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.IsDBNull

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-nextresult,  Next: connector-net-ref-mysqlclient-mysqldatareader-read,  Prev: connector-net-ref-mysqlclient-mysqldatareader-isdbnull,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.151 `MySqlDataReader.NextResult' Method
..............................................

Advances the data reader to the next result, when reading the results
of batch SQL statements.

*Syntax: Visual Basic*

     NotOverridable Public Function NextResult() As Boolean _
     _
       Implements IDataReader.NextResult

*Syntax: C#*

     public bool NextResult();

*Return Value*

*Implements*

IDataReader.NextResult

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-read,  Prev: connector-net-ref-mysqlclient-mysqldatareader-nextresult,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

20.2.4.152 `MySqlDataReader.Read' Method
........................................

Advances the MySqlDataReader to the next record.

*Syntax: Visual Basic*

     NotOverridable Public Function Read() As Boolean _
     _
       Implements IDataReader.Read

*Syntax: C#*

     public bool Read();

*Return Value*

*Implements*

IDataReader.Read

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1,  Up: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads

20.2.4.153 `MySqlCommand.ExecuteReader' Method
..............................................

*Syntax: Visual Basic*

     Overloads Public Function ExecuteReader( _
        ByVal behavior As CommandBehavior _
     ) As MySqlDataReader

*Syntax: C#*

     public MySqlDataReader ExecuteReader(
     CommandBehaviorbehavior
     );

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand.ExecuteReader Overload List:
connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-executescalar,  Next: connector-net-ref-mysqlclient-mysqlcommand-prepare,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.154 `MySqlCommand.ExecuteScalar' Method
..............................................

*Syntax: Visual Basic*

     NotOverridable Public Function ExecuteScalar() As Object _
     _
       Implements IDbCommand.ExecuteScalar

*Syntax: C#*

     public object ExecuteScalar();

*Implements*

IDbCommand.ExecuteScalar

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-prepare,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executescalar,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

20.2.4.155 `MySqlCommand.Prepare' Method
........................................

*Syntax: Visual Basic*

     NotOverridable Public Sub Prepare() _
     _
       Implements IDbCommand.Prepare

*Syntax: C#*

     public void Prepare();

*Implements*

IDbCommand.Prepare

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder,  Next: connector-net-ref-mysqlclient-mysqlexception,  Prev: connector-net-ref-mysqlclient-mysqlcommand,  Up: connector-net-ref-mysqlclient

20.2.4.156 `MySqlCommandBuilder' Class
......................................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandbuildermembers::  `MySqlCommandBuilder' Members

For a list of all members of this type, see *Note MySqlCommandBuilder
Members: connector-net-ref-mysqlclient-mysqlcommandbuildermembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlCommandBuilder_
       Inherits Component

*Syntax: C#*

     public sealed class MySqlCommandBuilder : Component

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlCommandBuilder Members:
connector-net-ref-mysqlclient-mysqlcommandbuildermembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuildermembers,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilder

20.2.4.157 `MySqlCommandBuilder' Members
........................................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads::  DeriveParameters Method
* connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor::  `MySqlCommandBuilder' Constructor
* connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter::  DataAdapter Property
* connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix::  QuotePrefix Property
* connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix::  QuoteSuffix Property
* connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand::  `MySqlCommandBuilder.GetDeleteCommand' Method
* connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand::  `MySqlCommandBuilder.GetInsertCommand' Method
* connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand::  `MySqlCommandBuilder.GetUpdateCommand' Method
* connector-net-ref-mysqlclient-mysqlcommandbuilder-refreshschema::  `MySqlCommandBuilder.RefreshSchema' Method

*Note MySqlCommandBuilder overview:
connector-net-ref-mysqlclient-mysqlcommandbuilder.

*Public Static (Shared) Methods*

*Note DeriveParameters:              Overloaded. Retrieves parameter
connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads.information from the stored
                                     procedure specified in the
                                     MySqlCommand and populates the
                                     Parameters collection of the
                                     specified MySqlCommand object. This
                                     method is not currently supported
                                     since stored procedures are not
                                     available in MySql.

*Public Instance Constructors*

*Note MySqlCommandBuilder:           Overloaded. Initializes a new
connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor.instance of the MySqlCommandBuilder
                                     class.

*Public Instance Properties*

Container(inherited from Component)  Gets the IContainerthat contains
                                     the Component.
*Note DataAdapter:                   
connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter.
*Note QuotePrefix:                   
connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix.
*Note QuoteSuffix:                   
connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix.
Site(inherited from Component)       Gets or sets the ISiteof the
                                     Component.

*Public Instance Methods*

CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
Dispose(inherited from Component)    Releases all resources used by the
                                     Component.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
*Note GetDeleteCommand:              
connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
*Note GetInsertCommand:              
connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note GetUpdateCommand:              
connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note RefreshSchema:                 
connector-net-ref-mysqlclient-mysqlcommandbuilder-refreshschema.
ToString(inherited from Component)   Returns a Stringcontaining the name
                                     of the Component, if any. This
                                     method should not be overridden.

*Public Instance Events*

Disposed(inherited from Component)   Adds an event handler to listen to
                                     the Disposedevent on the component.

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuildermembers,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

20.2.4.158 DeriveParameters Method
..................................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-1::  `MySqlCommandBuilder.DeriveParameters' Method
* connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-2::  `MySqlCommandBuilder.DeriveParameters' Method

Retrieves parameter information from the stored procedure specified in
the MySqlCommand and populates the Parameters collection of the
specified MySqlCommand object. This method is not currently supported
since stored procedures are not available in MySql.

*Overload List*

Retrieves parameter information from the stored procedure specified in
the MySqlCommand and populates the Parameters collection of the
specified MySqlCommand object. This method is not currently supported
since stored procedures are not available in MySql.

   * *Note public static void DeriveParameters(MySqlCommand);:
     connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-1.

   * *Note public static void DeriveParameters(MySqlCommand:
     (bool);)connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-2.

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-1,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads

20.2.4.159 `MySqlCommandBuilder.DeriveParameters' Method
........................................................

Retrieves parameter information from the stored procedure specified in
the MySqlCommand and populates the Parameters collection of the
specified MySqlCommand object. This method is not currently supported
since stored procedures are not available in MySql.

*Syntax: Visual Basic*

     Overloads Public Shared Sub DeriveParameters( _
        ByVal command As MySqlCommand _
     )

*Syntax: C#*

     public static void DeriveParameters(
     MySqlCommandcommand
     );

*Parameters*

   * `command': The MySqlCommand referencing the stored procedure from
     which the parameter information is to be derived. The derived
     parameters are added to the Parameters collection of the
     MySqlCommand.

*Exceptions*

*Exception Type*                     *Condition*
InvalidOperationException            The command text is not a valid
                                     stored procedure name.

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder.DeriveParameters Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-1,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads

20.2.4.160 `MySqlCommandBuilder.DeriveParameters' Method
........................................................

*Syntax: Visual Basic*

     Overloads Public Shared Sub DeriveParameters( _
        ByVal command As MySqlCommand, _
        ByVal useProc As Boolean _
     )

*Syntax: C#*

     public static void DeriveParameters(
     MySqlCommandcommand,
     booluseProc
     );

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder.DeriveParameters Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

20.2.4.161 `MySqlCommandBuilder' Constructor
............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor1::  `MySqlCommandBuilder' Constructor
* connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3::  `MySqlCommandBuilder' Constructor
* connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor4::  `MySqlCommandBuilder' Constructor
* connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor2::  `MySqlCommandBuilder' Constructor

Initializes a new instance of the *Note MySqlCommandBuilder:
connector-net-ref-mysqlclient-mysqlcommandbuilder.  class.

*Overload List*

Initializes a new instance of the *Note MySqlCommandBuilder:
connector-net-ref-mysqlclient-mysqlcommandbuilder.  class.

   * *Note public MySqlCommandBuilder();:
     connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor1.

   * *Note public MySqlCommandBuilder(MySqlDataAdapter);:
     connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3.

   * *Note public MySqlCommandBuilder(MySqlDataAdapter:
     (bool);)connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor4.

   * *Note public MySqlCommandBuilder(bool);:
     connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor2.

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor1,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor

20.2.4.162 `MySqlCommandBuilder' Constructor
............................................

Initializes a new instance of the *Note MySqlCommandBuilder:
connector-net-ref-mysqlclient-mysqlcommandbuilder.  class.

*Syntax: Visual Basic*

     Overloads Public Sub New()

*Syntax: C#*

     public MySqlCommandBuilder();

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor4,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor1,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor

20.2.4.163 `MySqlCommandBuilder' Constructor
............................................

* Menu:

* connector-net-ref-mysqlclient-mysqldataadapter::  `MySqlDataAdapter' Class

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal adapter As MySqlDataAdapter _
     )

*Syntax: C#*

     public MySqlCommandBuilder(
     MySqlDataAdapteradapter
     );

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3

20.2.4.164 `MySqlDataAdapter' Class
...................................

* Menu:

* connector-net-ref-mysqlclient-mysqldataadaptermembers::  `MySqlDataAdapter' Members

For a list of all members of this type, see *Note MySqlDataAdapter
Members: connector-net-ref-mysqlclient-mysqldataadaptermembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlDataAdapter_
       Inherits DbDataAdapter

*Syntax: C#*

     public sealed class MySqlDataAdapter : DbDataAdapter

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlDataAdapter Members:
connector-net-ref-mysqlclient-mysqldataadaptermembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadaptermembers,  Prev: connector-net-ref-mysqlclient-mysqldataadapter,  Up: connector-net-ref-mysqlclient-mysqldataadapter

20.2.4.165 `MySqlDataAdapter' Members
.....................................

* Menu:

* connector-net-ref-mysqlclient-mysqldataadapterconstructor::  `MySqlDataAdapter' Constructor
* connector-net-ref-mysqlclient-mysqldataadapter-deletecommand1::  DeleteCommand Property
* connector-net-ref-mysqlclient-mysqldataadapter-insertcommand1::  InsertCommand Property
* connector-net-ref-mysqlclient-mysqldataadapter-selectcommand1::  SelectCommand Property
* connector-net-ref-mysqlclient-mysqldataadapter-updatecommand1::  UpdateCommand Property
* connector-net-ref-mysqlclient-mysqldataadapter-rowupdated::  `MySqlDataAdapter.RowUpdated' Event
* connector-net-ref-mysqlclient-mysqldataadapter-rowupdating::  `MySqlDataAdapter.RowUpdating' Event

*Note MySqlDataAdapter overview:
connector-net-ref-mysqlclient-mysqldataadapter.

*Public Instance Constructors*

*Note MySqlDataAdapter:              Overloaded. Initializes a new
connector-net-ref-mysqlclient-mysqldataadapterconstructor.instance of the MySqlDataAdapter
                                     class.

*Public Instance Properties*

AcceptChangesDuringFill(inherited    Gets or sets a value indicating
from DataAdapter)                    whether AcceptChangesis called on a
                                     DataRowafter it is added to the
                                     DataTableduring any of the Fill
                                     operations.
AcceptChangesDuringUpdate(inherited  Gets or sets whether
from DataAdapter)                    AcceptChangesis called during a
                                     Update.
Container(inherited from Component)  Gets the IContainerthat contains
                                     the Component.
ContinueUpdateOnError(inherited      Gets or sets a value that specifies
from DataAdapter)                    whether to generate an exception
                                     when an error is encountered during
                                     a row update.
*Note DeleteCommand:                 Overloaded.
connector-net-ref-mysqlclient-mysqldataadapter-deletecommand1.
FillLoadOption(inherited from        Gets or sets the LoadOptionthat
DataAdapter)                         determines how the adapter fills the
                                     DataTablefrom the DbDataReader.
*Note InsertCommand:                 Overloaded.
connector-net-ref-mysqlclient-mysqldataadapter-insertcommand1.
MissingMappingAction(inherited from  Determines the action to take when
DataAdapter)                         incoming data does not have a
                                     matching table or column.
MissingSchemaAction(inherited from   Determines the action to take when
DataAdapter)                         existing DataSetschema does not
                                     match incoming data.
ReturnProviderSpecificTypes(inheritedGets or sets whether the Fillmethod
from DataAdapter)                    should return provider-specific
                                     values or common CLS-compliant
                                     values.
*Note SelectCommand:                 Overloaded.
connector-net-ref-mysqlclient-mysqldataadapter-selectcommand1.
Site(inherited from Component)       Gets or sets the ISiteof the
                                     Component.
TableMappings(inherited from         Gets a collection that provides the
DataAdapter)                         master mapping between a source
                                     table and a DataTable.
UpdateBatchSize(inherited from       Gets or sets a value that enables
DbDataAdapter)                       or disables batch processing
                                     support, and specifies the number
                                     of commands that can be executed in
                                     a batch.
*Note UpdateCommand:                 Overloaded.
connector-net-ref-mysqlclient-mysqldataadapter-updatecommand1.

*Public Instance Methods*

CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
Dispose(inherited from Component)    Releases all resources used by the
                                     Component.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
Fill(inherited from DbDataAdapter)   Overloaded. Adds or refreshes rows
                                     in the DataSetto match those in the
                                     data source using the DataSetname,
                                     and creates a DataTablenamed
                                     "Table."
FillSchema(inherited from            Overloaded. Configures the schema
DbDataAdapter)                       of the specified DataTablebased on
                                     the specified SchemaType.
GetFillParameters(inherited from     Gets the parameters set by the user
DbDataAdapter)                       when executing an SQL *Note
                                     `SELECT': select.  statement.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
ResetFillLoadOption(inherited from   Resets FillLoadOptionto its default
DataAdapter)                         state and causes Fillto honor
                                     AcceptChangesDuringFill.
ShouldSerializeAcceptChangesDuringFill(inheritedDetermines whether the
from DataAdapter)                    AcceptChangesDuringFillproperty
                                     should be persisted.
ShouldSerializeFillLoadOption(inheritedDetermines whether the
from DataAdapter)                    FillLoadOptionproperty should be
                                     persisted.
ToString(inherited from Component)   Returns a Stringcontaining the name
                                     of the Component, if any. This
                                     method should not be overridden.
Update(inherited from DbDataAdapter) Overloaded. Calls the respective
                                     INSERT, UPDATE, or DELETE statements
                                     for each inserted, updated, or
                                     deleted row in the specified
                                     DataSet.

*Public Instance Events*

Disposed(inherited from Component)   Adds an event handler to listen to
                                     the Disposedevent on the component.
FillError(inherited from             Returned when an error occurs
DataAdapter)                         during a fill operation.
*Note RowUpdated:                    Occurs during Update after a
connector-net-ref-mysqlclient-mysqldataadapter-rowupdated.command is executed against the data
                                     source. The attempt to update is
                                     made, so the event fires.
*Note RowUpdating:                   Occurs during Update before a
connector-net-ref-mysqlclient-mysqldataadapter-rowupdating.command is executed against the data
                                     source. The attempt to update is
                                     made, so the event fires.

*Protected Internal Instance Properties*

FillCommandBehavior(inherited from   Gets or sets the behavior of the
DbDataAdapter)                       command used to fill the data
                                     adapter.

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor,  Next: connector-net-ref-mysqlclient-mysqldataadapter-deletecommand1,  Prev: connector-net-ref-mysqlclient-mysqldataadaptermembers,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

20.2.4.166 `MySqlDataAdapter' Constructor
.........................................

* Menu:

* connector-net-ref-mysqlclient-mysqldataadapterconstructor1::  `MySqlDataAdapter' Constructor
* connector-net-ref-mysqlclient-mysqldataadapterconstructor2::  `MySqlDataAdapter' Constructor
* connector-net-ref-mysqlclient-mysqldataadapterconstructor3::  `MySqlDataAdapter' Constructor
* connector-net-ref-mysqlclient-mysqldataadapterconstructor4::  `MySqlDataAdapter' Constructor

Initializes a new instance of the *Note MySqlDataAdapter:
connector-net-ref-mysqlclient-mysqldataadapter.  class.

*Overload List*

Initializes a new instance of the *Note MySqlDataAdapter:
connector-net-ref-mysqlclient-mysqldataadapter.  class.

   * *Note public MySqlDataAdapter();:
     connector-net-ref-mysqlclient-mysqldataadapterconstructor1.

   * *Note public MySqlDataAdapter(MySqlCommand);:
     connector-net-ref-mysqlclient-mysqldataadapterconstructor2.

   * *Note public MySqlDataAdapter(string:
     (MySqlConnection);)connector-net-ref-mysqlclient-mysqldataadapterconstructor3.

   * *Note public MySqlDataAdapter(string:
     (string);)connector-net-ref-mysqlclient-mysqldataadapterconstructor4.

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor1,  Next: connector-net-ref-mysqlclient-mysqldataadapterconstructor2,  Prev: connector-net-ref-mysqlclient-mysqldataadapterconstructor,  Up: connector-net-ref-mysqlclient-mysqldataadapterconstructor

20.2.4.167 `MySqlDataAdapter' Constructor
.........................................

Initializes a new instance of the *Note MySqlDataAdapter:
connector-net-ref-mysqlclient-mysqldataadapter.  class.

*Syntax: Visual Basic*

     Overloads Public Sub New()

*Syntax: C#*

     public MySqlDataAdapter();

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataAdapter Constructor Overload List:
connector-net-ref-mysqlclient-mysqldataadapterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor2,  Next: connector-net-ref-mysqlclient-mysqldataadapterconstructor3,  Prev: connector-net-ref-mysqlclient-mysqldataadapterconstructor1,  Up: connector-net-ref-mysqlclient-mysqldataadapterconstructor

20.2.4.168 `MySqlDataAdapter' Constructor
.........................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal selectCommand As MySqlCommand _
     )

*Syntax: C#*

     public MySqlDataAdapter(
     MySqlCommandselectCommand
     );

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataAdapter Constructor Overload List:
connector-net-ref-mysqlclient-mysqldataadapterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor3,  Next: connector-net-ref-mysqlclient-mysqldataadapterconstructor4,  Prev: connector-net-ref-mysqlclient-mysqldataadapterconstructor2,  Up: connector-net-ref-mysqlclient-mysqldataadapterconstructor

20.2.4.169 `MySqlDataAdapter' Constructor
.........................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal selectCommandText As String, _
        ByVal connection As MySqlConnection _
     )

*Syntax: C#*

     public MySqlDataAdapter(
     stringselectCommandText,
     MySqlConnectionconnection
     );

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataAdapter Constructor Overload List:
connector-net-ref-mysqlclient-mysqldataadapterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor4,  Prev: connector-net-ref-mysqlclient-mysqldataadapterconstructor3,  Up: connector-net-ref-mysqlclient-mysqldataadapterconstructor

20.2.4.170 `MySqlDataAdapter' Constructor
.........................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal selectCommandText As String, _
        ByVal selectConnString As String _
     )

*Syntax: C#*

     public MySqlDataAdapter(
     stringselectCommandText,
     stringselectConnString
     );

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataAdapter Constructor Overload List:
connector-net-ref-mysqlclient-mysqldataadapterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-deletecommand1,  Next: connector-net-ref-mysqlclient-mysqldataadapter-insertcommand1,  Prev: connector-net-ref-mysqlclient-mysqldataadapterconstructor,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

20.2.4.171 DeleteCommand Property
.................................

*Syntax: Visual Basic*

     Overloads Public Property DeleteCommand As MySqlCommand

*Syntax: C#*

     new public MySqlCommand DeleteCommand {get; set;}

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-insertcommand1,  Next: connector-net-ref-mysqlclient-mysqldataadapter-selectcommand1,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-deletecommand1,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

20.2.4.172 InsertCommand Property
.................................

*Syntax: Visual Basic*

     Overloads Public Property InsertCommand As MySqlCommand

*Syntax: C#*

     new public MySqlCommand InsertCommand {get; set;}

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-selectcommand1,  Next: connector-net-ref-mysqlclient-mysqldataadapter-updatecommand1,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-insertcommand1,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

20.2.4.173 SelectCommand Property
.................................

*Syntax: Visual Basic*

     Overloads Public Property SelectCommand As MySqlCommand

*Syntax: C#*

     new public MySqlCommand SelectCommand {get; set;}

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-updatecommand1,  Next: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-selectcommand1,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

20.2.4.174 UpdateCommand Property
.................................

*Syntax: Visual Basic*

     Overloads Public Property UpdateCommand As MySqlCommand

*Syntax: C#*

     new public MySqlCommand UpdateCommand {get; set;}

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated,  Next: connector-net-ref-mysqlclient-mysqldataadapter-rowupdating,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-updatecommand1,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

20.2.4.175 `MySqlDataAdapter.RowUpdated' Event
..............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler::  `MySqlRowUpdatedEventHandler' Delegate

Occurs during Update after a command is executed against the data
source. The attempt to update is made, so the event fires.

*Syntax: Visual Basic*

     Public Event RowUpdated As MySqlRowUpdatedEventHandler

*Syntax: C#*

     public event MySqlRowUpdatedEventHandler RowUpdated;

*Event Data*

The event handler receives an argument of type *Note
MySqlRowUpdatedEventArgs:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs.  containing
data related to this event. The following
MySqlRowUpdatedEventArgsproperties provide information specific to this
event.

*Property*                           *Description*
*Note Command:                       Gets or sets the MySqlCommand
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command1.executed when Update is called.
Errors                               Gets any errors generated by the
                                     .NET Framework data provider when
                                     the Commandwas executed.
RecordsAffected                      Gets the number of rows changed,
                                     inserted, or deleted by execution of
                                     the SQL statement.
Row                                  Gets the DataRowsent through an
                                     Update.
RowCount                             Gets the number of rows processed
                                     in a batch of updated records.
StatementType                        Gets the type of SQL statement
                                     executed.
Status                               Gets the UpdateStatusof the
                                     Commandproperty.
TableMapping                         Gets the DataTableMappingsent
                                     through an Update.

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated,  Up: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated

20.2.4.176 `MySqlRowUpdatedEventHandler' Delegate
.................................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatedeventargs::  `MySqlRowUpdatedEventArgs' Class

Represents the method that will handle the RowUpdatedevent of a *Note
MySqlDataAdapter: connector-net-ref-mysqlclient-mysqldataadapter .

*Syntax: Visual Basic*

     Public Delegate Sub MySqlRowUpdatedEventHandler( _
        ByVal sender As Object, _
        ByVal e As MySqlRowUpdatedEventArgs _
     )

*Syntax: C#*

     public delegate void MySqlRowUpdatedEventHandler(
     objectsender,
     MySqlRowUpdatedEventArgse
     );

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler,  Up: connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler

20.2.4.177 `MySqlRowUpdatedEventArgs' Class
...........................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers::  `MySqlRowUpdatedEventArgs' Members

Provides data for the RowUpdated event. This class cannot be inherited.

For a list of all members of this type, see *Note
MySqlRowUpdatedEventArgs Members:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlRowUpdatedEventArgs_
       Inherits RowUpdatedEventArgs

*Syntax: C#*

     public sealed class MySqlRowUpdatedEventArgs : RowUpdatedEventArgs

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlRowUpdatedEventArgs Members:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs,  Up: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs

20.2.4.178 `MySqlRowUpdatedEventArgs' Members
.............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatedeventargsconstructor::  `MySqlRowUpdatedEventArgs' Constructor
* connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command1::  Command Property

*Note MySqlRowUpdatedEventArgs overview:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs.

*Public Instance Constructors*

*Note MySqlRowUpdatedEventArgs       Initializes a new instance of the
Constructor:                         MySqlRowUpdatedEventArgs class.
connector-net-ref-mysqlclient-mysqlrowupdatedeventargsconstructor.

*Public Instance Properties*

*Note Command:                       Overloaded. Gets or sets the
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command1.MySqlCommand executed when Update is
                                     called.
Errors(inherited from                Gets any errors generated by the
RowUpdatedEventArgs)                 .NET Framework data provider when
                                     the Commandwas executed.
RecordsAffected(inherited from       Gets the number of rows changed,
RowUpdatedEventArgs)                 inserted, or deleted by execution of
                                     the SQL statement.
Row(inherited from                   Gets the DataRowsent through an
RowUpdatedEventArgs)                 Update.
RowCount(inherited from              Gets the number of rows processed
RowUpdatedEventArgs)                 in a batch of updated records.
StatementType(inherited from         Gets the type of SQL statement
RowUpdatedEventArgs)                 executed.
Status(inherited from                Gets the UpdateStatusof the
RowUpdatedEventArgs)                 Commandproperty.
TableMapping(inherited from          Gets the DataTableMappingsent
RowUpdatedEventArgs)                 through an Update.

*Public Instance Methods*

CopyToRows(inherited from            Overloaded. Copies references to
RowUpdatedEventArgs)                 the modified rows into the provided
                                     array.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlRowUpdatedEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsconstructor,  Next: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command1,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers,  Up: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers

20.2.4.179 `MySqlRowUpdatedEventArgs' Constructor
.................................................

Initializes a new instance of the MySqlRowUpdatedEventArgs class.

*Syntax: Visual Basic*

     Public Sub New( _
        ByVal row As DataRow, _
        ByVal command As IDbCommand, _
        ByVal statementType As StatementType, _
        ByVal tableMapping As DataTableMapping _
     )

*Syntax: C#*

     public MySqlRowUpdatedEventArgs(
     DataRowrow,
     IDbCommandcommand,
     StatementTypestatementType,
     DataTableMappingtableMapping
     );

*Parameters*

   * `row': The DataRowsent through an Update.

   * `command': The IDbCommandexecuted when Updateis called.

   * `statementType': One of the StatementTypevalues that specifies the
     type of query executed.

   * `tableMapping': The DataTableMappingsent through an Update.

*See Also*

*Note MySqlRowUpdatedEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command1,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsconstructor,  Up: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers

20.2.4.180 Command Property
...........................

Gets or sets the MySqlCommand executed when Update is called.

*Syntax: Visual Basic*

     Overloads Public ReadOnly Property Command As MySqlCommand

*Syntax: C#*

     new public MySqlCommand Command {get;}

*See Also*

*Note MySqlRowUpdatedEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-rowupdating,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

20.2.4.181 `MySqlDataAdapter.RowUpdating' Event
...............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler::  `MySqlRowUpdatingEventHandler' Delegate

Occurs during Update before a command is executed against the data
source. The attempt to update is made, so the event fires.

*Syntax: Visual Basic*

     Public Event RowUpdating As MySqlRowUpdatingEventHandler

*Syntax: C#*

     public event MySqlRowUpdatingEventHandler RowUpdating;

*Event Data*

The event handler receives an argument of type *Note
MySqlRowUpdatingEventArgs:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs.  containing
data related to this event. The following
MySqlRowUpdatingEventArgsproperties provide information specific to
this event.

*Property*                           *Description*
*Note Command:                       Gets or sets the MySqlCommand to
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command1.execute when performing the Update.
Errors                               Gets any errors generated by the
                                     .NET Framework data provider when
                                     the Commandexecutes.
Row                                  Gets the DataRowthat will be sent
                                     to the server as part of an insert,
                                     update, or delete operation.
StatementType                        Gets the type of SQL statement to
                                     execute.
Status                               Gets or sets the UpdateStatusof the
                                     Commandproperty.
TableMapping                         Gets the DataTableMappingto send
                                     through the Update.

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-rowupdating,  Up: connector-net-ref-mysqlclient-mysqldataadapter-rowupdating

20.2.4.182 `MySqlRowUpdatingEventHandler' Delegate
..................................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatingeventargs::  `MySqlRowUpdatingEventArgs' Class

Represents the method that will handle the RowUpdatingevent of a *Note
MySqlDataAdapter: connector-net-ref-mysqlclient-mysqldataadapter .

*Syntax: Visual Basic*

     Public Delegate Sub MySqlRowUpdatingEventHandler( _
        ByVal sender As Object, _
        ByVal e As MySqlRowUpdatingEventArgs _
     )

*Syntax: C#*

     public delegate void MySqlRowUpdatingEventHandler(
     objectsender,
     MySqlRowUpdatingEventArgse
     );

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler,  Up: connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler

20.2.4.183 `MySqlRowUpdatingEventArgs' Class
............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers::  `MySqlRowUpdatingEventArgs' Members

Provides data for the RowUpdating event. This class cannot be inherited.

For a list of all members of this type, see *Note
MySqlRowUpdatingEventArgs Members:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlRowUpdatingEventArgs_
       Inherits RowUpdatingEventArgs

*Syntax: C#*

     public sealed class MySqlRowUpdatingEventArgs : RowUpdatingEventArgs

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlRowUpdatingEventArgs Members:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs,  Up: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs

20.2.4.184 `MySqlRowUpdatingEventArgs' Members
..............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatingeventargsconstructor::  `MySqlRowUpdatingEventArgs' Constructor
* connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command1::  Command Property

*Note MySqlRowUpdatingEventArgs overview:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs.

*Public Instance Constructors*

*Note MySqlRowUpdatingEventArgs      Initializes a new instance of the
Constructor:                         MySqlRowUpdatingEventArgs class.
connector-net-ref-mysqlclient-mysqlrowupdatingeventargsconstructor.

*Public Instance Properties*

*Note Command:                       Overloaded. Gets or sets the
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command1.MySqlCommand to execute when
                                     performing the Update.
Errors(inherited from                Gets any errors generated by the
RowUpdatingEventArgs)                .NET Framework data provider when
                                     the Commandexecutes.
Row(inherited from                   Gets the DataRowthat will be sent
RowUpdatingEventArgs)                to the server as part of an insert,
                                     update, or delete operation.
StatementType(inherited from         Gets the type of SQL statement to
RowUpdatingEventArgs)                execute.
Status(inherited from                Gets or sets the UpdateStatusof the
RowUpdatingEventArgs)                Commandproperty.
TableMapping(inherited from          Gets the DataTableMappingto send
RowUpdatingEventArgs)                through the Update.

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlRowUpdatingEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsconstructor,  Next: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command1,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers,  Up: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers

20.2.4.185 `MySqlRowUpdatingEventArgs' Constructor
..................................................

Initializes a new instance of the MySqlRowUpdatingEventArgs class.

*Syntax: Visual Basic*

     Public Sub New( _
        ByVal row As DataRow, _
        ByVal command As IDbCommand, _
        ByVal statementType As StatementType, _
        ByVal tableMapping As DataTableMapping _
     )

*Syntax: C#*

     public MySqlRowUpdatingEventArgs(
     DataRowrow,
     IDbCommandcommand,
     StatementTypestatementType,
     DataTableMappingtableMapping
     );

*Parameters*

   * `row': The DataRowto Update.

   * `command': The IDbCommandto execute during Update.

   * `statementType': One of the StatementTypevalues that specifies the
     type of query executed.

   * `tableMapping': The DataTableMappingsent through an Update.

*See Also*

*Note MySqlRowUpdatingEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command1,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsconstructor,  Up: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers

20.2.4.186 Command Property
...........................

Gets or sets the MySqlCommand to execute when performing the Update.

*Syntax: Visual Basic*

     Overloads Public Property Command As MySqlCommand

*Syntax: C#*

     new public MySqlCommand Command {get; set;}

*See Also*

*Note MySqlRowUpdatingEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor4,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor

20.2.4.187 `MySqlCommandBuilder' Constructor
............................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal adapter As MySqlDataAdapter, _
        ByVal lastOneWins As Boolean _
     )

*Syntax: C#*

     public MySqlCommandBuilder(
     MySqlDataAdapteradapter,
     boollastOneWins
     );

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor4,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor

20.2.4.188 `MySqlCommandBuilder' Constructor
............................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal lastOneWins As Boolean _
     )

*Syntax: C#*

     public MySqlCommandBuilder(
     boollastOneWins
     );

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

20.2.4.189 DataAdapter Property
...............................

*Syntax: Visual Basic*

     Public Property DataAdapter As MySqlDataAdapter

*Syntax: C#*

     public MySqlDataAdapter DataAdapter {get; set;}

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

20.2.4.190 QuotePrefix Property
...............................

*Syntax: Visual Basic*

     Public Property QuotePrefix As String

*Syntax: C#*

     public string QuotePrefix {get; set;}

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

20.2.4.191 QuoteSuffix Property
...............................

*Syntax: Visual Basic*

     Public Property QuoteSuffix As String

*Syntax: C#*

     public string QuoteSuffix {get; set;}

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

20.2.4.192 `MySqlCommandBuilder.GetDeleteCommand' Method
........................................................

*Syntax: Visual Basic*

     Public Function GetDeleteCommand() As MySqlCommand

*Syntax: C#*

     public MySqlCommand GetDeleteCommand();

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

20.2.4.193 `MySqlCommandBuilder.GetInsertCommand' Method
........................................................

*Syntax: Visual Basic*

     Public Function GetInsertCommand() As MySqlCommand

*Syntax: C#*

     public MySqlCommand GetInsertCommand();

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-refreshschema,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

20.2.4.194 `MySqlCommandBuilder.GetUpdateCommand' Method
........................................................

*Syntax: Visual Basic*

     Public Function GetUpdateCommand() As MySqlCommand

*Syntax: C#*

     public MySqlCommand GetUpdateCommand();

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-refreshschema,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

20.2.4.195 `MySqlCommandBuilder.RefreshSchema' Method
.....................................................

*Syntax: Visual Basic*

     Public Sub RefreshSchema()

*Syntax: C#*

     public void RefreshSchema();

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlexception,  Next: connector-net-ref-mysqlclient-mysqlhelper,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder,  Up: connector-net-ref-mysqlclient

20.2.4.196 `MySqlException' Class
.................................

* Menu:

* connector-net-ref-mysqlclient-mysqlexceptionmembers::  `MySqlException' Members

The exception that is thrown when MySQL returns an error. This class
cannot be inherited.

For a list of all members of this type, see *Note MySqlException
Members: connector-net-ref-mysqlclient-mysqlexceptionmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlException_
       Inherits SystemException

*Syntax: C#*

     public sealed class MySqlException : SystemException

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlException Members:
connector-net-ref-mysqlclient-mysqlexceptionmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlexceptionmembers,  Prev: connector-net-ref-mysqlclient-mysqlexception,  Up: connector-net-ref-mysqlclient-mysqlexception

20.2.4.197 `MySqlException' Members
...................................

* Menu:

* connector-net-ref-mysqlclient-mysqlexception-number::  Number Property

*Note MySqlException overview:
connector-net-ref-mysqlclient-mysqlexception.

*Public Instance Properties*

Data(inherited from Exception)       Gets a collection of key/value
                                     pairs that provide additional,
                                     user-defined information about the
                                     exception.
HelpLink(inherited from Exception)   Gets or sets a link to the help
                                     file associated with this exception.
InnerException(inherited from        Gets the Exceptioninstance that
Exception)                           caused the current exception.
Message(inherited from Exception)    Gets a message that describes the
                                     current exception.
*Note Number:                        Gets a number that identifies the
connector-net-ref-mysqlclient-mysqlexception-number.type of error. This number
                                     corresponds to the error numbers
                                     given in *Note
                                     error-messages-server::.
Source(inherited from Exception)     Gets or sets the name of the
                                     application or the object that
                                     causes the error.
StackTrace(inherited from Exception) Gets a string representation of the
                                     frames on the call stack at the time
                                     the current exception was thrown.
TargetSite(inherited from Exception) Gets the method that throws the
                                     current exception.

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetBaseException(inherited from      When overridden in a derived class,
Exception)                           returns the Exceptionthat is the
                                     root cause of one or more
                                     subsequent exceptions.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetObjectData(inherited from         When overridden in a derived class,
Exception)                           sets the SerializationInfowith
                                     information about the exception.
GetType(inherited from Exception)    Gets the runtime type of the
                                     current instance.
ToString(inherited from Exception)   Creates and returns a string
                                     representation of the current
                                     exception.

*See Also*

*Note MySqlException Class:
connector-net-ref-mysqlclient-mysqlexception , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlexception-number,  Prev: connector-net-ref-mysqlclient-mysqlexceptionmembers,  Up: connector-net-ref-mysqlclient-mysqlexceptionmembers

20.2.4.198 Number Property
..........................

Gets a number that identifies the type of error.

*Syntax: Visual Basic*

     Public ReadOnly Property Number As Integer

*Syntax: C#*

     public int Number {get;}

*See Also*

*Note MySqlException Class:
connector-net-ref-mysqlclient-mysqlexception , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper,  Next: connector-net-ref-mysqlclient-mysqlerrorcode,  Prev: connector-net-ref-mysqlclient-mysqlexception,  Up: connector-net-ref-mysqlclient

20.2.4.199 `MySqlHelper' Class
..............................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelpermembers::  `MySqlHelper' Members

Helper class that makes it easier to work with the provider.

For a list of all members of this type, see *Note MySqlHelper Members:
connector-net-ref-mysqlclient-mysqlhelpermembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlHelper

*Syntax: C#*

     public sealed class MySqlHelper

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlHelper Members:
connector-net-ref-mysqlclient-mysqlhelpermembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelpermembers,  Prev: connector-net-ref-mysqlclient-mysqlhelper,  Up: connector-net-ref-mysqlclient-mysqlhelper

20.2.4.200 `MySqlHelper' Members
................................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelper-executedatarow::  `MySqlHelper.ExecuteDataRow' Method
* connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads::  ExecuteDataset Method
* connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads::  ExecuteNonQuery Method
* connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads::  ExecuteReader Method
* connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads::  ExecuteScalar Method
* connector-net-ref-mysqlclient-mysqlhelper-updatedataset::  `MySqlHelper.UpdateDataSet' Method

*Note MySqlHelper overview: connector-net-ref-mysqlclient-mysqlhelper.

*Public Static (Shared) Methods*

*Note ExecuteDataRow:                Executes a single SQL statement and
connector-net-ref-mysqlclient-mysqlhelper-executedatarow.returns the first row of the
                                     resultset. A new MySqlConnection
                                     object is created, opened, and
                                     closed during this method.
*Note ExecuteDataset:                Overloaded. Executes a single SQL
connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads.statement and returns the resultset
                                     in a DataSet. A new MySqlConnection
                                     object is created, opened, and
                                     closed during this method.
*Note ExecuteNonQuery:               Overloaded. Executes a single
connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads.command against a MySQL database.
                                     The *Note MySqlConnection:
                                     connector-net-ref-mysqlclient-mysqlconnection.
                                     is assumed to be open when the
                                     method is called and remains open
                                     after the method completes.
*Note ExecuteReader:                 Overloaded. Executes a single
connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads.command against a MySQL database.
*Note ExecuteScalar:                 Overloaded. Execute a single
connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads.command against a MySQL database.
*Note UpdateDataSet:                 Updates the given table with data
connector-net-ref-mysqlclient-mysqlhelper-updatedataset.from the given DataSet

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedatarow,  Next: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads,  Prev: connector-net-ref-mysqlclient-mysqlhelpermembers,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

20.2.4.201 `MySqlHelper.ExecuteDataRow' Method
..............................................

Executes a single SQL statement and returns the first row of the
resultset. A new MySqlConnection object is created, opened, and closed
during this method.

*Syntax: Visual Basic*

     Public Shared Function ExecuteDataRow( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ParamArray parms As MySqlParameter() _
     ) As DataRow

*Syntax: C#*

     public static DataRow ExecuteDataRow(
     stringconnectionString,
     stringcommandText,
        params MySqlParameter[]parms
     );

*Parameters*

   * `connectionString': Settings to be used for the connection

   * `commandText': Command to execute

   * `parms': Parameters to use for the command

*Return Value*

DataRow containing the first row of the resultset

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads,  Next: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedatarow,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

20.2.4.202 ExecuteDataset Method
................................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-3::  `MySqlHelper.ExecuteDataset' Method
* connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-4::  `MySqlHelper.ExecuteDataset' Method
* connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-1::  `MySqlHelper.ExecuteDataset' Method
* connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-2::  `MySqlHelper.ExecuteDataset' Method

Executes a single SQL statement and returns the resultset in a DataSet.
The state of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object remains
unchanged after execution of this method.

*Overload List*

Executes a single SQL statement and returns the resultset in a DataSet.
The state of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object remains
unchanged after execution of this method.

   * *Note public static DataSet ExecuteDataset(MySqlConnection:
     (string);)connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-3.

Executes a single SQL statement and returns the resultset in a DataSet.
The state of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object remains
unchanged after execution of this method.

   * *Note public static DataSet ExecuteDataset(MySqlConnection:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-4.

Executes a single SQL statement and returns the resultset in a DataSet.
A new MySqlConnection object is created, opened, and closed during this
method.

   * *Note public static DataSet ExecuteDataset(string:
     (string);)connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-1.

Executes a single SQL statement and returns the resultset in a DataSet.
A new MySqlConnection object is created, opened, and closed during this
method.

   * *Note public static DataSet ExecuteDataset(string:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-2.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-3,  Next: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-4,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads

20.2.4.203 `MySqlHelper.ExecuteDataset' Method
..............................................

Executes a single SQL statement and returns the resultset in a DataSet.
The state of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object remains
unchanged after execution of this method.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteDataset( _
        ByVal connection As MySqlConnection, _
        ByVal commandText As String _
     ) As DataSet

*Syntax: C#*

     public static DataSet ExecuteDataset(
     MySqlConnectionconnection,
     stringcommandText
     );

*Parameters*

   * `connection': *Note MySqlConnection:
     connector-net-ref-mysqlclient-mysqlconnection.  object to use

   * `commandText': Command to execute

*Return Value*

DataSetcontaining the resultset

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteDataset Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-4,  Next: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-1,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-3,  Up: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads

20.2.4.204 `MySqlHelper.ExecuteDataset' Method
..............................................

Executes a single SQL statement and returns the resultset in a DataSet.
The state of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object remains
unchanged after execution of this method.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteDataset( _
        ByVal connection As MySqlConnection, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As DataSet

*Syntax: C#*

     public static DataSet ExecuteDataset(
     MySqlConnectionconnection,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connection': *Note MySqlConnection:
     connector-net-ref-mysqlclient-mysqlconnection.  object to use

   * `commandText': Command to execute

   * `commandParameters': Parameters to use for the command

*Return Value*

DataSetcontaining the resultset

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteDataset Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-1,  Next: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-4,  Up: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads

20.2.4.205 `MySqlHelper.ExecuteDataset' Method
..............................................

Executes a single SQL statement and returns the resultset in a DataSet.
A new MySqlConnection object is created, opened, and closed during this
method.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteDataset( _
        ByVal connectionString As String, _
        ByVal commandText As String _
     ) As DataSet

*Syntax: C#*

     public static DataSet ExecuteDataset(
     stringconnectionString,
     stringcommandText
     );

*Parameters*

   * `connectionString': Settings to be used for the connection

   * `commandText': Command to execute

*Return Value*

DataSetcontaining the resultset

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteDataset Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-1,  Up: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads

20.2.4.206 `MySqlHelper.ExecuteDataset' Method
..............................................

Executes a single SQL statement and returns the resultset in a DataSet.
A new MySqlConnection object is created, opened, and closed during this
method.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteDataset( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As DataSet

*Syntax: C#*

     public static DataSet ExecuteDataset(
     stringconnectionString,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connectionString': Settings to be used for the connection

   * `commandText': Command to execute

   * `commandParameters': Parameters to use for the command

*Return Value*

DataSetcontaining the resultset

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteDataset Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads,  Next: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

20.2.4.207 ExecuteNonQuery Method
.................................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-1::  `MySqlHelper.ExecuteNonQuery' Method
* connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-2::  `MySqlHelper.ExecuteNonQuery' Method

Executes a single command against a MySQL database. The *Note
MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection.  is
assumed to be open when the method is called and remains open after the
method completes.

*Overload List*

Executes a single command against a MySQL database. The *Note
MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection.  is
assumed to be open when the method is called and remains open after the
method completes.

   * *Note public static int ExecuteNonQuery(MySqlConnection:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-1.

Executes a single command against a MySQL database. A new *Note
MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection.  is
created using the *Note ConnectionString:
connector-net-ref-mysqlclient-mysqlconnection-connectionstring.  given.

   * *Note public static int ExecuteNonQuery(string:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-2.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-1,  Next: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads

20.2.4.208 `MySqlHelper.ExecuteNonQuery' Method
...............................................

Executes a single command against a MySQL database. The *Note
MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection.  is
assumed to be open when the method is called and remains open after the
method completes.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteNonQuery( _
        ByVal connection As MySqlConnection, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As Integer

*Syntax: C#*

     public static int ExecuteNonQuery(
     MySqlConnectionconnection,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connection': *Note MySqlConnection:
     connector-net-ref-mysqlclient-mysqlconnection.  object to use

   * `commandText': SQL statement to be executed

   * `commandParameters': Array of *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  objects to use with
     the command.

*Return Value*

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteNonQuery Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-1,  Up: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads

20.2.4.209 `MySqlHelper.ExecuteNonQuery' Method
...............................................

Executes a single command against a MySQL database. A new *Note
MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection.  is
created using the *Note ConnectionString:
connector-net-ref-mysqlclient-mysqlconnection-connectionstring.  given.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteNonQuery( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ParamArray parms As MySqlParameter() _
     ) As Integer

*Syntax: C#*

     public static int ExecuteNonQuery(
     stringconnectionString,
     stringcommandText,
        params MySqlParameter[]parms
     );

*Parameters*

   * `connectionString': *Note ConnectionString:
     connector-net-ref-mysqlclient-mysqlconnection-connectionstring.
     to use

   * `commandText': SQL statement to be executed

   * `parms': Array of *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  objects to use with
     the command.

*Return Value*

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteNonQuery Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads,  Next: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

20.2.4.210 ExecuteReader Method
...............................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-1::  `MySqlHelper.ExecuteReader' Method
* connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-2::  `MySqlHelper.ExecuteReader' Method

Executes a single command against a MySQL database.

*Overload List*

Executes a single command against a MySQL database.

   * *Note public static MySqlDataReader ExecuteReader(string:
     (string);)connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-1.

Executes a single command against a MySQL database.

   * *Note public static MySqlDataReader ExecuteReader(string:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-2.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-1,  Next: connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads

20.2.4.211 `MySqlHelper.ExecuteReader' Method
.............................................

Executes a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteReader( _
        ByVal connectionString As String, _
        ByVal commandText As String _
     ) As MySqlDataReader

*Syntax: C#*

     public static MySqlDataReader ExecuteReader(
     stringconnectionString,
     stringcommandText
     );

*Parameters*

   * `connectionString': Settings to use for this command

   * `commandText': Command text to use

*Return Value*

*Note MySqlDataReader: connector-net-ref-mysqlclient-mysqldatareader.
object ready to read the results of the command

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteReader Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-1,  Up: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads

20.2.4.212 `MySqlHelper.ExecuteReader' Method
.............................................

Executes a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteReader( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As MySqlDataReader

*Syntax: C#*

     public static MySqlDataReader ExecuteReader(
     stringconnectionString,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connectionString': Settings to use for this command

   * `commandText': Command text to use

   * `commandParameters': Array of *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  objects to use with
     the command

*Return Value*

*Note MySqlDataReader: connector-net-ref-mysqlclient-mysqldatareader.
object ready to read the results of the command

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteReader Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads,  Next: connector-net-ref-mysqlclient-mysqlhelper-updatedataset,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

20.2.4.213 ExecuteScalar Method
...............................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-3::  `MySqlHelper.ExecuteScalar' Method
* connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-4::  `MySqlHelper.ExecuteScalar' Method
* connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-1::  `MySqlHelper.ExecuteScalar' Method
* connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-2::  `MySqlHelper.ExecuteScalar' Method

Execute a single command against a MySQL database.

*Overload List*

Execute a single command against a MySQL database.

   * *Note public static object ExecuteScalar(MySqlConnection:
     (string);)connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-3.

Execute a single command against a MySQL database.

   * *Note public static object ExecuteScalar(MySqlConnection:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-4.

Execute a single command against a MySQL database.

   * *Note public static object ExecuteScalar(string:
     (string);)connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-1.

Execute a single command against a MySQL database.

   * *Note public static object ExecuteScalar(string:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-2.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-3,  Next: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-4,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads

20.2.4.214 `MySqlHelper.ExecuteScalar' Method
.............................................

Execute a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteScalar( _
        ByVal connection As MySqlConnection, _
        ByVal commandText As String _
     ) As Object

*Syntax: C#*

     public static object ExecuteScalar(
     MySqlConnectionconnection,
     stringcommandText
     );

*Parameters*

   * `connection': *Note MySqlConnection:
     connector-net-ref-mysqlclient-mysqlconnection.  object to use

   * `commandText': Command text to use for the command

*Return Value*

The first column of the first row in the result set, or a null
reference if the result set is empty.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteScalar Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-4,  Next: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-1,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-3,  Up: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads

20.2.4.215 `MySqlHelper.ExecuteScalar' Method
.............................................

Execute a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteScalar( _
        ByVal connection As MySqlConnection, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As Object

*Syntax: C#*

     public static object ExecuteScalar(
     MySqlConnectionconnection,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connection': *Note MySqlConnection:
     connector-net-ref-mysqlclient-mysqlconnection.  object to use

   * `commandText': Command text to use for the command

   * `commandParameters': Parameters to use for the command

*Return Value*

The first column of the first row in the result set, or a null
reference if the result set is empty.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteScalar Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-1,  Next: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-4,  Up: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads

20.2.4.216 `MySqlHelper.ExecuteScalar' Method
.............................................

Execute a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteScalar( _
        ByVal connectionString As String, _
        ByVal commandText As String _
     ) As Object

*Syntax: C#*

     public static object ExecuteScalar(
     stringconnectionString,
     stringcommandText
     );

*Parameters*

   * `connectionString': Settings to use for the update

   * `commandText': Command text to use for the update

*Return Value*

The first column of the first row in the result set, or a null
reference if the result set is empty.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteScalar Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-1,  Up: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads

20.2.4.217 `MySqlHelper.ExecuteScalar' Method
.............................................

Execute a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteScalar( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As Object

*Syntax: C#*

     public static object ExecuteScalar(
     stringconnectionString,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connectionString': Settings to use for the command

   * `commandText': Command text to use for the command

   * `commandParameters': Parameters to use for the command

*Return Value*

The first column of the first row in the result set, or a null
reference if the result set is empty.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteScalar Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-updatedataset,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

20.2.4.218 `MySqlHelper.UpdateDataSet' Method
.............................................

Updates the given table with data from the given DataSet

*Syntax: Visual Basic*

     Public Shared Sub UpdateDataSet( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ByVal ds As DataSet, _
        ByVal tablename As String _
     )

*Syntax: C#*

     public static void UpdateDataSet(
     stringconnectionString,
     stringcommandText,
     DataSetds,
     stringtablename
     );

*Parameters*

   * `connectionString': Settings to use for the update

   * `commandText': Command text to use for the update

   * `ds': DataSetcontaining the new data to use in the update

   * `tablename': Tablename in the data set to update

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerrorcode,  Prev: connector-net-ref-mysqlclient-mysqlhelper,  Up: connector-net-ref-mysqlclient

20.2.4.219 `MySqlErrorCode' Enumeration
.......................................

*Syntax: Visual Basic*

     Public Enum MySqlErrorCode

*Syntax: C#*

     public enum MySqlErrorCode

*Members*

*Member Name*                        *Description*
PacketTooLarge                       
PasswordNotAllowed                   
DuplicateKeyEntry                    
HostNotPrivileged                    
PasswordNoMatch                      
AnonymousUser                        
DuplicateKey                         
KeyNotFound                          
DuplicateKeyName                     

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-types,  Prev: connector-net-ref-mysqlclient,  Up: connector-net-ref

20.2.4.220 `MySql.Data.Types'
.............................

* Menu:

* connector-net-ref-typeshierarchy::  `MySql.Data.TypesHierarchy'
* connector-net-ref-types-mysqlconversionexception::  `MySqlConversionException' Class
* connector-net-ref-types-mysqldatetime::  `MySqlDateTime' Class

*Note Namespace hierarchy: connector-net-ref-typeshierarchy.

*Classes*

*Class*                              *Description*
*Note MySqlConversionException:      Summary description for
connector-net-ref-types-mysqlconversionexception.MySqlConversionException.
*Note MySqlDateTime:                 Summary description for
connector-net-ref-types-mysqldatetime.MySqlDateTime.
*Note MySqlValue:                    
connector-net-ref-types-mysqlvalue.  


File: manual.info,  Node: connector-net-ref-typeshierarchy,  Next: connector-net-ref-types-mysqlconversionexception,  Prev: connector-net-ref-types,  Up: connector-net-ref-types

20.2.4.221 `MySql.Data.TypesHierarchy'
......................................

*See Also*

*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlconversionexception,  Next: connector-net-ref-types-mysqldatetime,  Prev: connector-net-ref-typeshierarchy,  Up: connector-net-ref-types

20.2.4.222 `MySqlConversionException' Class
...........................................

* Menu:

* connector-net-ref-types-mysqlconversionexceptionmembers::  `MySqlConversionException' Members

Summary description for MySqlConversionException.

For a list of all members of this type, see *Note
MySqlConversionException Members:
connector-net-ref-types-mysqlconversionexceptionmembers .

*Syntax: Visual Basic*

     Public Class MySqlConversionException_
       Inherits ApplicationException

*Syntax: C#*

     public class MySqlConversionException : ApplicationException

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.Types: connector-net-ref-types.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlConversionException Members:
connector-net-ref-types-mysqlconversionexceptionmembers , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlconversionexceptionmembers,  Prev: connector-net-ref-types-mysqlconversionexception,  Up: connector-net-ref-types-mysqlconversionexception

20.2.4.223 `MySqlConversionException' Members
.............................................

* Menu:

* connector-net-ref-types-mysqlconversionexceptionconstructor::  `MySqlConversionException' Constructor

*Note MySqlConversionException overview:
connector-net-ref-types-mysqlconversionexception.

*Public Instance Constructors*

*Note MySqlConversionException       Ctor
Constructor:                         
connector-net-ref-types-mysqlconversionexceptionconstructor.

*Public Instance Properties*

Data(inherited from Exception)       Gets a collection of key/value
                                     pairs that provide additional,
                                     user-defined information about the
                                     exception.
HelpLink(inherited from Exception)   Gets or sets a link to the help
                                     file associated with this exception.
InnerException(inherited from        Gets the Exceptioninstance that
Exception)                           caused the current exception.
Message(inherited from Exception)    Gets a message that describes the
                                     current exception.
Source(inherited from Exception)     Gets or sets the name of the
                                     application or the object that
                                     causes the error.
StackTrace(inherited from Exception) Gets a string representation of the
                                     frames on the call stack at the time
                                     the current exception was thrown.
TargetSite(inherited from Exception) Gets the method that throws the
                                     current exception.

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetBaseException(inherited from      When overridden in a derived class,
Exception)                           returns the Exceptionthat is the
                                     root cause of one or more
                                     subsequent exceptions.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetObjectData(inherited from         When overridden in a derived class,
Exception)                           sets the SerializationInfowith
                                     information about the exception.
GetType(inherited from Exception)    Gets the runtime type of the
                                     current instance.
ToString(inherited from Exception)   Creates and returns a string
                                     representation of the current
                                     exception.

*Protected Instance Properties*

HResult(inherited from Exception)    Gets or sets HRESULT, a coded
                                     numerical value that is assigned to
                                     a specific exception.

*Protected Instance Methods*

Finalize(inherited from Object)      Allows an Objectto attempt to free
                                     resources and perform other cleanup
                                     operations before the Objectis
                                     reclaimed by garbage collection.
MemberwiseClone(inherited from       Creates a shallow copy of the
Object)                              current Object.

*See Also*

*Note MySqlConversionException Class:
connector-net-ref-types-mysqlconversionexception , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlconversionexceptionconstructor,  Prev: connector-net-ref-types-mysqlconversionexceptionmembers,  Up: connector-net-ref-types-mysqlconversionexceptionmembers

20.2.4.224 `MySqlConversionException' Constructor
.................................................

*Syntax: Visual Basic*

     Public Sub New( _
        ByVal msg As String _
     )

*Syntax: C#*

     public MySqlConversionException(
     stringmsg
     );

*See Also*

*Note MySqlConversionException Class:
connector-net-ref-types-mysqlconversionexception , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime,  Prev: connector-net-ref-types-mysqlconversionexception,  Up: connector-net-ref-types

20.2.4.225 `MySqlDateTime' Class
................................

* Menu:

* connector-net-ref-types-mysqldatetimemembers::  `MySqlDateTime' Members

Summary description for MySqlDateTime.

For a list of all members of this type, see *Note MySqlDateTime
Members: connector-net-ref-types-mysqldatetimemembers .

*Syntax: Visual Basic*

     Public Class MySqlDateTime_
       Inherits MySqlValue_
       Implements IConvertible, IComparable

*Syntax: C#*

     public class MySqlDateTime : MySqlValue, IConvertible, IComparable

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.Types: connector-net-ref-types.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlDateTime Members:
connector-net-ref-types-mysqldatetimemembers , *Note MySql.Data.Types
Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetimemembers,  Prev: connector-net-ref-types-mysqldatetime,  Up: connector-net-ref-types-mysqldatetime

20.2.4.226 `MySqlDateTime' Members
..................................

* Menu:

* connector-net-ref-types-mysqldatetime-op-explicit::  `MySqlDateTime' Explicit `MySqlDateTime' to `DateTime' Conversion
* connector-net-ref-types-mysqldatetime-day::  Day Property
* connector-net-ref-types-mysqldatetime-hour::  Hour Property
* connector-net-ref-types-mysqlvalue-isnull::  IsNull Property
* connector-net-ref-types-mysqldatetime-isvaliddatetime::  IsValidDateTime Property
* connector-net-ref-types-mysqldatetime-minute::  Minute Property
* connector-net-ref-types-mysqldatetime-month::  Month Property
* connector-net-ref-types-mysqldatetime-second::  Second Property
* connector-net-ref-types-mysqldatetime-year::  Year Property
* connector-net-ref-types-mysqldatetime-getdatetime::  `MySqlDateTime.GetDateTime' Method
* connector-net-ref-types-mysqldatetime-tostring::  `MySqlDateTime.ToString' Method

*Note MySqlDateTime overview: connector-net-ref-types-mysqldatetime.

*Public Static (Shared) Type Conversions*

*Note Explicit MySqlDateTime to      
DateTime Conversion:                 
connector-net-ref-types-mysqldatetime-op-explicit.

*Public Instance Properties*

*Note Day:                           Returns the day portion of this
connector-net-ref-types-mysqldatetime-day.datetime
*Note Hour:                          Returns the hour portion of this
connector-net-ref-types-mysqldatetime-hour.datetime
*Note IsNull:                        
connector-net-ref-types-mysqlvalue-isnull.
(inherited from MySqlValue)          
*Note IsValidDateTime:               Indicates if this object contains a
connector-net-ref-types-mysqldatetime-isvaliddatetime.value that can be represented as a
                                     DateTime
*Note Minute:                        Returns the minute portion of this
connector-net-ref-types-mysqldatetime-minute.datetime
*Note Month:                         Returns the month portion of this
connector-net-ref-types-mysqldatetime-month.datetime
*Note Second:                        Returns the second portion of this
connector-net-ref-types-mysqldatetime-second.datetime
*Note ValueAsObject:                 Returns the value of this field as
connector-net-ref-types-mysqlvalue-valueasobject.an object
(inherited from MySqlValue)          
*Note Year:                          Returns the year portion of this
connector-net-ref-types-mysqldatetime-year.datetime

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
*Note GetDateTime:                   Returns this value as a DateTime
connector-net-ref-types-mysqldatetime-getdatetime.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note ToString:                      Returns a MySQL specific string
connector-net-ref-types-mysqldatetime-tostring.representation of this value

*Protected Instance Fields*

*Note classType:                     The system type represented by this
connector-net-ref-types-mysqlvalue-classtype.value
(inherited from MySqlValue)          
*Note dbType:                        The generic dbtype of this value
connector-net-ref-types-mysqlvalue-dbtype.
(inherited from MySqlValue)          
*Note isNull:                        Is this value null
connector-net-ref-types-mysqlvalue-isnull.
(inherited from MySqlValue)          
*Note mySqlDbType:                   The specific MySQL db type
connector-net-ref-types-mysqlvalue-mysqldbtype.
(inherited from MySqlValue)          
*Note mySqlTypeName:                 The MySQL specific typename of this
connector-net-ref-types-mysqlvalue-mysqltypename.value
(inherited from MySqlValue)          
*Note objectValue:                   
connector-net-ref-types-mysqlvalue-objectvalue.
(inherited from MySqlValue)          

*Protected Instance Methods*

Finalize(inherited from Object)      Allows an Objectto attempt to free
                                     resources and perform other cleanup
                                     operations before the Objectis
                                     reclaimed by garbage collection.
MemberwiseClone(inherited from       Creates a shallow copy of the
Object)                              current Object.

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-op-explicit,  Next: connector-net-ref-types-mysqldatetime-day,  Prev: connector-net-ref-types-mysqldatetimemembers,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.227 `MySqlDateTime' Explicit `MySqlDateTime' to `DateTime' Conversion
............................................................................

*Syntax: Visual Basic*

     MySqlDateTime.op_Explicit(val)

*Syntax: C#*

     public static explicit operator DateTime(
     MySqlDateTimeval
     );

*Parameters*

   * `val':

*Return Value*

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-day,  Next: connector-net-ref-types-mysqldatetime-hour,  Prev: connector-net-ref-types-mysqldatetime-op-explicit,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.228 Day Property
.......................

Returns the day portion of this datetime

*Syntax: Visual Basic*

     Public Property Day As Integer

*Syntax: C#*

     public int Day {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-hour,  Next: connector-net-ref-types-mysqlvalue-isnull,  Prev: connector-net-ref-types-mysqldatetime-day,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.229 Hour Property
........................

Returns the hour portion of this datetime

*Syntax: Visual Basic*

     Public Property Hour As Integer

*Syntax: C#*

     public int Hour {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-isnull,  Next: connector-net-ref-types-mysqldatetime-isvaliddatetime,  Prev: connector-net-ref-types-mysqldatetime-hour,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.230 IsNull Property
..........................

* Menu:

* connector-net-ref-types-mysqlvalue::  `MySqlValue' Class

*Syntax: Visual Basic*

     Public Property IsNull As Boolean

*Syntax: C#*

     public bool IsNull {get; set;}

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue,  Prev: connector-net-ref-types-mysqlvalue-isnull,  Up: connector-net-ref-types-mysqlvalue-isnull

20.2.4.231 `MySqlValue' Class
.............................

* Menu:

* connector-net-ref-types-mysqlvaluemembers::  `MySqlValue' Members

For a list of all members of this type, see *Note MySqlValue Members:
connector-net-ref-types-mysqlvaluemembers .

*Syntax: Visual Basic*

     MustInherit Public Class MySqlValue

*Syntax: C#*

     public abstract class MySqlValue

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.Types: connector-net-ref-types.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlValue Members: connector-net-ref-types-mysqlvaluemembers ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvaluemembers,  Prev: connector-net-ref-types-mysqlvalue,  Up: connector-net-ref-types-mysqlvalue

20.2.4.232 `MySqlValue' Members
...............................

* Menu:

* connector-net-ref-types-mysqlvalue-numberformat::  `MySqlValue.numberFormat' Field
* connector-net-ref-types-mysqlvalueconstructor::  `MySqlValue' Constructor
* connector-net-ref-types-mysqlvalue-valueasobject::  ValueAsObject Property
* connector-net-ref-types-mysqlvalue-tostring::  `MySqlValue.ToString' Method
* connector-net-ref-types-mysqlvalue-classtype::  `MySqlValue.classType' Field
* connector-net-ref-types-mysqlvalue-dbtype::  `MySqlValue.dbType' Field
* connector-net-ref-types-mysqlvalue-mysqldbtype::  `MySqlValue.mySqlDbType' Field
* connector-net-ref-types-mysqlvalue-mysqltypename::  `MySqlValue.mySqlTypeName' Field
* connector-net-ref-types-mysqlvalue-objectvalue::  `MySqlValue.objectValue' Field

*Note MySqlValue overview: connector-net-ref-types-mysqlvalue.

*Protected Static (Shared) Fields*

*Note numberFormat:                  
connector-net-ref-types-mysqlvalue-numberformat.

*Public Instance Constructors*

*Note MySqlValue Constructor:        Initializes a new instance of the
connector-net-ref-types-mysqlvalueconstructor.*Note MySqlValue:
                                     connector-net-ref-types-mysqlvalue.
                                     class.

*Public Instance Properties*

*Note IsNull:                        
connector-net-ref-types-mysqlvalue-isnull.
*Note ValueAsObject:                 Returns the value of this field as
connector-net-ref-types-mysqlvalue-valueasobject.an object

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note ToString:                      Returns a string representation of
connector-net-ref-types-mysqlvalue-tostring.this value

*Protected Instance Fields*

*Note classType:                     The system type represented by this
connector-net-ref-types-mysqlvalue-classtype.value
*Note dbType:                        The generic dbtype of this value
connector-net-ref-types-mysqlvalue-dbtype.
*Note isNull:                        Is this value null
connector-net-ref-types-mysqlvalue-isnull.
*Note mySqlDbType:                   The specific MySQL db type
connector-net-ref-types-mysqlvalue-mysqldbtype.
*Note mySqlTypeName:                 The MySQL specific typename of this
connector-net-ref-types-mysqlvalue-mysqltypename.value
*Note objectValue:                   
connector-net-ref-types-mysqlvalue-objectvalue.

*Protected Instance Methods*

Finalize(inherited from Object)      Allows an Objectto attempt to free
                                     resources and perform other cleanup
                                     operations before the Objectis
                                     reclaimed by garbage collection.
MemberwiseClone(inherited from       Creates a shallow copy of the
Object)                              current Object.

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-numberformat,  Next: connector-net-ref-types-mysqlvalueconstructor,  Prev: connector-net-ref-types-mysqlvaluemembers,  Up: connector-net-ref-types-mysqlvaluemembers

20.2.4.233 `MySqlValue.numberFormat' Field
..........................................

*Syntax: Visual Basic*

     Protected Shared numberFormat As NumberFormatInfo

*Syntax: C#*

     protected static NumberFormatInfo numberFormat;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalueconstructor,  Next: connector-net-ref-types-mysqlvalue-valueasobject,  Prev: connector-net-ref-types-mysqlvalue-numberformat,  Up: connector-net-ref-types-mysqlvaluemembers

20.2.4.234 `MySqlValue' Constructor
...................................

Initializes a new instance of the *Note MySqlValue:
connector-net-ref-types-mysqlvalue.  class.

*Syntax: Visual Basic*

     Public Sub New()

*Syntax: C#*

     public MySqlValue();

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-valueasobject,  Next: connector-net-ref-types-mysqlvalue-tostring,  Prev: connector-net-ref-types-mysqlvalueconstructor,  Up: connector-net-ref-types-mysqlvaluemembers

20.2.4.235 ValueAsObject Property
.................................

Returns the value of this field as an object

*Syntax: Visual Basic*

     Public ReadOnly Property ValueAsObject As Object

*Syntax: C#*

     public object ValueAsObject {get;}

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-tostring,  Next: connector-net-ref-types-mysqlvalue-classtype,  Prev: connector-net-ref-types-mysqlvalue-valueasobject,  Up: connector-net-ref-types-mysqlvaluemembers

20.2.4.236 `MySqlValue.ToString' Method
.......................................

Returns a string representation of this value

*Syntax: Visual Basic*

     Overrides Public Function ToString() As String

*Syntax: C#*

     public override string ToString();

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-classtype,  Next: connector-net-ref-types-mysqlvalue-dbtype,  Prev: connector-net-ref-types-mysqlvalue-tostring,  Up: connector-net-ref-types-mysqlvaluemembers

20.2.4.237 `MySqlValue.classType' Field
.......................................

The system type represented by this value

*Syntax: Visual Basic*

     Protected classType As Type

*Syntax: C#*

     protected Type classType;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-dbtype,  Next: connector-net-ref-types-mysqlvalue-mysqldbtype,  Prev: connector-net-ref-types-mysqlvalue-classtype,  Up: connector-net-ref-types-mysqlvaluemembers

20.2.4.238 `MySqlValue.dbType' Field
....................................

The generic dbtype of this value

*Syntax: Visual Basic*

     Protected dbType As DbType

*Syntax: C#*

     protected DbType dbType;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-mysqldbtype,  Next: connector-net-ref-types-mysqlvalue-mysqltypename,  Prev: connector-net-ref-types-mysqlvalue-dbtype,  Up: connector-net-ref-types-mysqlvaluemembers

20.2.4.239 `MySqlValue.mySqlDbType' Field
.........................................

The specific MySQL db type

*Syntax: Visual Basic*

     Protected mySqlDbType As MySqlDbType

*Syntax: C#*

     protected MySqlDbType mySqlDbType;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-mysqltypename,  Next: connector-net-ref-types-mysqlvalue-objectvalue,  Prev: connector-net-ref-types-mysqlvalue-mysqldbtype,  Up: connector-net-ref-types-mysqlvaluemembers

20.2.4.240 `MySqlValue.mySqlTypeName' Field
...........................................

The MySQL specific typename of this value

*Syntax: Visual Basic*

     Protected mySqlTypeName As String

*Syntax: C#*

     protected string mySqlTypeName;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-objectvalue,  Prev: connector-net-ref-types-mysqlvalue-mysqltypename,  Up: connector-net-ref-types-mysqlvaluemembers

20.2.4.241 `MySqlValue.objectValue' Field
.........................................

*Syntax: Visual Basic*

     Protected objectValue As Object

*Syntax: C#*

     protected object objectValue;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-isvaliddatetime,  Next: connector-net-ref-types-mysqldatetime-minute,  Prev: connector-net-ref-types-mysqlvalue-isnull,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.242 IsValidDateTime Property
...................................

Indicates if this object contains a value that can be represented as a
DateTime

*Syntax: Visual Basic*

     Public ReadOnly Property IsValidDateTime As Boolean

*Syntax: C#*

     public bool IsValidDateTime {get;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-minute,  Next: connector-net-ref-types-mysqldatetime-month,  Prev: connector-net-ref-types-mysqldatetime-isvaliddatetime,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.243 Minute Property
..........................

Returns the minute portion of this datetime

*Syntax: Visual Basic*

     Public Property Minute As Integer

*Syntax: C#*

     public int Minute {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-month,  Next: connector-net-ref-types-mysqldatetime-second,  Prev: connector-net-ref-types-mysqldatetime-minute,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.244 Month Property
.........................

Returns the month portion of this datetime

*Syntax: Visual Basic*

     Public Property Month As Integer

*Syntax: C#*

     public int Month {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-second,  Next: connector-net-ref-types-mysqldatetime-year,  Prev: connector-net-ref-types-mysqldatetime-month,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.245 Second Property
..........................

Returns the second portion of this datetime

*Syntax: Visual Basic*

     Public Property Second As Integer

*Syntax: C#*

     public int Second {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-year,  Next: connector-net-ref-types-mysqldatetime-getdatetime,  Prev: connector-net-ref-types-mysqldatetime-second,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.246 Year Property
........................

Returns the year portion of this datetime

*Syntax: Visual Basic*

     Public Property Year As Integer

*Syntax: C#*

     public int Year {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-getdatetime,  Next: connector-net-ref-types-mysqldatetime-tostring,  Prev: connector-net-ref-types-mysqldatetime-year,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.247 `MySqlDateTime.GetDateTime' Method
.............................................

Returns this value as a DateTime

*Syntax: Visual Basic*

     Public Function GetDateTime() As Date

*Syntax: C#*

     public DateTime GetDateTime();

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-tostring,  Prev: connector-net-ref-types-mysqldatetime-getdatetime,  Up: connector-net-ref-types-mysqldatetimemembers

20.2.4.248 `MySqlDateTime.ToString' Method
..........................................

Returns a MySQL specific string representation of this value

*Syntax: Visual Basic*

     Overrides Public Function ToString() As String

*Syntax: C#*

     public override string ToString();

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-using,  Next: connect-net-support,  Prev: connector-net-ref,  Up: connector-net

20.2.5 Connector/NET Notes and Tips
-----------------------------------

* Menu:

* connector-net-using-connecting::  Connecting to MySQL Using Connector/NET
* connector-net-using-connection-pooling::  Using Connector/NET with Connection Pooling
* connector-net-using-prepared::  Using the Connector/NET with Prepared Statements
* connector-net-using-stored::   Accessing Stored Procedures with Connector/NET
* connector-net-using-blob::     Handling BLOB Data With Connector/NET
* connector-net-using-crystal::  Using Connector/NET with Crystal Reports
* connector-net-using-datetime::  Handling Date and Time Information in Connector/NET
* connector-net-using-faq::      Frequently Asked Questions

In this section we will cover some of the more common use cases for
Connector/NET, including BLOB handling, date handling, and using
Connector/NET with common tools such as Crystal Reports.


File: manual.info,  Node: connector-net-using-connecting,  Next: connector-net-using-connection-pooling,  Prev: connector-net-using,  Up: connector-net-using

20.2.5.1 Connecting to MySQL Using Connector/NET
................................................

* Menu:

* connector-net-using-connecting-introduction::  Introduction
* connector-net-using-connecting-connection-string::  Creating a Connection String
* connector-net-using-connecting-open::  Opening a Connection
* connector-net-using-connecting-errors::  Handling Connection Errors


File: manual.info,  Node: connector-net-using-connecting-introduction,  Next: connector-net-using-connecting-connection-string,  Prev: connector-net-using-connecting,  Up: connector-net-using-connecting

20.2.5.2 Introduction
.....................

All interaction between a .NET application and the MySQL server is
routed through a `MySqlConnection' object. Before your application can
interact with the server, a `MySqlConnection' object must be instanced,
configured, and opened.

Even when using the `MySqlHelper' class, a `MySqlConnection' object is
created by the helper class.

In this section, we will describe how to connect to MySQL using the
`MySqlConnection' object.


File: manual.info,  Node: connector-net-using-connecting-connection-string,  Next: connector-net-using-connecting-open,  Prev: connector-net-using-connecting-introduction,  Up: connector-net-using-connecting

20.2.5.3 Creating a Connection String
.....................................

The `MySqlConnection' object is configured using a connection string. A
connection string contains sever key/value pairs, separated by
semicolons. Each key/value pair is joined with an equals sign.

The following is a sample connection string:

         Server=127.0.0.1;Uid=root;Pwd=12345;Database=test;

In this example, the `MySqlConnection' object is configured to connect
to a MySQL server at `127.0.0.1', with a user name of `root' and a
password of `12345'. The default database for all statements will be
the `test' database.

The following options are typically used (a full list of options is
available in the API documentation for *Note
connector-net-examples-mysqlconnection-connectionstring::):

   * `Server': The name or network address of the instance of MySQL to
     which to connect. The default is `localhost'. Aliases include
     `host', `Data Source', `DataSource', `Address', `Addr' and `Network
     Address'.

   * `Uid': The MySQL user account to use when connecting. Aliases
     include `User Id', `Username' and `User name'.

   * `Pwd': The password for the MySQL account being used. Alias
     `Password' can also be used.

   * `Database': The default database that all statements are applied
     to. Default is `mysql'. Alias `Initial Catalog' can also be used.

   * `Port': The port MySQL is using to listen for connections. Default
     is `3306'.


File: manual.info,  Node: connector-net-using-connecting-open,  Next: connector-net-using-connecting-errors,  Prev: connector-net-using-connecting-connection-string,  Up: connector-net-using-connecting

20.2.5.4 Opening a Connection
.............................

Once you have created a connection string it can be used to open a
connection to the MySQL server.

The following code is used to create a `MySqlConnection' object, assign
the connection string, and open the connection.

Visual Basic Example

     Dim conn As New MySql.Data.MySqlClient.MySqlConnection
     Dim myConnectionString as String

     myConnectionString = "server=127.0.0.1;" _
                 & "uid=root;" _
                 & "pwd=12345;" _
                 & "database=test;"

     Try
       conn.ConnectionString = myConnectionString
       conn.Open()

     Catch ex As MySql.Data.MySqlClient.MySqlException
       MessageBox.Show(ex.Message)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     string myConnectionString;

     myConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         conn = new MySql.Data.MySqlClient.MySqlConnection();
         conn.ConnectionString = myConnectionString;
         conn.Open();
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show(ex.Message);
     }

You can also pass the connection string to the constructor of the
`MySqlConnection' class:

Visual Basic Example

     Dim myConnectionString as String

     myConnectionString = "server=127.0.0.1;" _
                   & "uid=root;" _
                   & "pwd=12345;" _
                   & "database=test;"

     Try
         Dim conn As New MySql.Data.MySqlClient.MySqlConnection(myConnectionString)
         conn.Open()
     Catch ex As MySql.Data.MySqlClient.MySqlException
        MessageBox.Show(ex.Message)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     string myConnectionString;

     myConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         conn = new MySql.Data.MySqlClient.MySqlConnection(myConnectionString);
         conn.Open();
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show(ex.Message);
     }

Once the connection is open it can be used by the other Connector/NET
classes to communicate with the MySQL server.


File: manual.info,  Node: connector-net-using-connecting-errors,  Prev: connector-net-using-connecting-open,  Up: connector-net-using-connecting

20.2.5.5 Handling Connection Errors
...................................

Because connecting to an external server is unpredictable, it is
important to add error handling to your .NET application.  When there
is an error connecting, the `MySqlConnection' class will return a
`MySqlException' object. This object has two properties that are of
interest when handling errors:

   * `Message': A message that describes the current exception.

   * `Number': The MySQL error number.

When handling errors, you can your application's response based on the
error number. The two most common error numbers when connecting are as
follows:

   * `0': Cannot connect to server.

   * `1045': Invalid user name and/or password.

The following code shows how to adapt the application's response based
on the actual error:

Visual Basic Example

     Dim myConnectionString as String

     myConnectionString = "server=127.0.0.1;" _
               & "uid=root;" _
               & "pwd=12345;" _
               & "database=test;"

     Try
         Dim conn As New MySql.Data.MySqlClient.MySqlConnection(myConnectionString)
         conn.Open()
     Catch ex As MySql.Data.MySqlClient.MySqlException
         Select Case ex.Number
             Case 0
                 MessageBox.Show("Cannot connect to server. Contact administrator")
             Case 1045
                 MessageBox.Show("Invalid username/password, please try again")
         End Select
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     string myConnectionString;

     myConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         conn = new MySql.Data.MySqlClient.MySqlConnection(myConnectionString);
         conn.Open();
     }
         catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         switch (ex.Number)
         {
             case 0:
                 MessageBox.Show("Cannot connect to server.  Contact administrator");
             case 1045:
                 MessageBox.Show("Invalid username/password, please try again");
         }
     }

*Important*:

Note that if you are using multilanguage databases you must specify the
character set in the connection string. If you do not specify the
character set, the connection defaults to the `latin1' charset. You can
specify the character set as part of the connection string, for example:

     MySqlConnection myConnection = new MySqlConnection("server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;Charset=latin1;");


File: manual.info,  Node: connector-net-using-connection-pooling,  Next: connector-net-using-prepared,  Prev: connector-net-using-connecting,  Up: connector-net-using

20.2.5.6 Using Connector/NET with Connection Pooling
....................................................

The Connector/NET supports connection pooling. This is enabled by
default, but can be turned off via connection string options.  See
*Note connector-net-examples-mysqlconnection-connectionstring:: for
further information.

Connection pooling works by keeping the native connection to the server
live when the client disposes of a `MySqlConnection'. Subsequently, if
a new `MySqlConnection' object is opened, it will be created from the
connection pool, rather than creating a new native connection. This
improves performance.

To work as designed, it is best to let the connection pooling system
manage all connections. You should not create a globally accessible
instance of `MySqlConnection' and then manually open and close it. This
interferes with the way the pooling works and can lead to unpredictable
results or even exceptions.

One approach that simplifies things is to avoid manually creating a
`MySqlConnection' object. Instead use the overloaded methods that take
a connection string as an argument. Using this approach, Connector/NET
will automatically create, open, close and destroy connections, using
the connection pooling system for best performance.

Typed Datasets and the `MembershipProvider' and `RoleProvider' classes
use this approach. Most classes that have methods that take a
`MySqlConnection' as an argument, also have methods that take a
connection string as an argument. This includes `MySqlDataAdapter'.

Instead of manually creating `MySqlCommand' objects, you can use the
static methods of the `MySqlHelper' class. These take a connection
string as an argument, and they fully support connection pooling.


File: manual.info,  Node: connector-net-using-prepared,  Next: connector-net-using-stored,  Prev: connector-net-using-connection-pooling,  Up: connector-net-using

20.2.5.7 Using the Connector/NET with Prepared Statements
.........................................................

* Menu:

* connector-net-using-prepared-introduction::  Introduction
* connector-net-using-prepared-preparing::  Preparing Statements in Connector/NET


File: manual.info,  Node: connector-net-using-prepared-introduction,  Next: connector-net-using-prepared-preparing,  Prev: connector-net-using-prepared,  Up: connector-net-using-prepared

20.2.5.8 Introduction
.....................

As of MySQL 4.1, it is possible to use prepared statements with
Connector/NET. Use of prepared statements can provide significant
performance improvements on queries that are executed more than once.

Prepared execution is faster than direct execution for statements
executed more than once, primarily because the query is parsed only
once. In the case of direct execution, the query is parsed every time
it is executed. Prepared execution also can provide a reduction of
network traffic because for each execution of the prepared statement,
it is necessary only to send the data for the parameters.

Another advantage of prepared statements is that it uses a binary
protocol that makes data transfer between client and server more
efficient.


File: manual.info,  Node: connector-net-using-prepared-preparing,  Prev: connector-net-using-prepared-introduction,  Up: connector-net-using-prepared

20.2.5.9 Preparing Statements in Connector/NET
..............................................

To prepare a statement, create a command object and set the
`.CommandText' property to your query.

After entering your statement, call the `.Prepare' method of the
`MySqlCommand' object. After the statement is prepared, add parameters
for each of the dynamic elements in the query.

After you enter your query and enter parameters, execute the statement
using the `.ExecuteNonQuery()', `.ExecuteScalar()', or `.ExecuteReader'
methods.

For subsequent executions, you need only modify the values of the
parameters and call the execute method again, there is no need to set
the `.CommandText' property or redefine the parameters.

Visual Basic Example

     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand

     conn.ConnectionString = strConnection

     Try
        conn.Open()
        cmd.Connection = conn

        cmd.CommandText = "INSERT INTO myTable VALUES(NULL, @number, @text)"
        cmd.Prepare()

        cmd.Parameters.Add("@number", 1)
        cmd.Parameters.Add("@text", "One")

        For i = 1 To 1000
            cmd.Parameters["@number"].Value = i
            cmd.Parameters["@text"].Value = "A string value"

            cmd.ExecuteNonQuery()
          Next
     Catch ex As MySqlException
         MessageBox.Show("Error " & ex.Number & " has occurred: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();

     conn.ConnectionString = strConnection;

     try
     {
         conn.Open();
         cmd.Connection = conn;

         cmd.CommandText = "INSERT INTO myTable VALUES(NULL, @number, @text)";
         cmd.Prepare();

         cmd.Parameters.Add("@number", 1);
         cmd.Parameters.Add("@text", "One");

         for (int i=1; i <= 1000; i++)
         {
             cmd.Parameters["@number"].Value = i;
             cmd.Parameters["@text"].Value = "A string value";

             cmd.ExecuteNonQuery();
         }
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show("Error " + ex.Number + " has occurred: " + ex.Message,
             "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }


File: manual.info,  Node: connector-net-using-stored,  Next: connector-net-using-blob,  Prev: connector-net-using-prepared,  Up: connector-net-using

20.2.5.10 Accessing Stored Procedures with Connector/NET
........................................................

* Menu:

* connector-net-using-stored-introduction::  Introduction
* connector-net-using-stored-creating::  Creating Stored Procedures from Connector/NET
* connector-net-using-stored-calling::  Calling a Stored Procedure from Connector/NET


File: manual.info,  Node: connector-net-using-stored-introduction,  Next: connector-net-using-stored-creating,  Prev: connector-net-using-stored,  Up: connector-net-using-stored

20.2.5.11 Introduction
......................

With the release of MySQL version 5 the MySQL server now supports
stored procedures with the SQL 2003 stored procedure syntax.

A stored procedure is a set of SQL statements that can be stored in the
server. Once this has been done, clients do not need to keep reissuing
the individual statements but can refer to the stored procedure instead.

Stored procedures can be particularly useful in situations such as the
following:

   * When multiple client applications are written in different
     languages or work on different platforms, but need to perform the
     same database operations.

   * When security is paramount. Banks, for example, use stored
     procedures for all common operations. This provides a consistent
     and secure environment, and procedures can ensure that each
     operation is properly logged. In such a setup, applications and
     users would not get any access to the database tables directly,
     but can only execute specific stored procedures.

Connector/NET supports the calling of stored procedures through the
`MySqlCommand' object. Data can be passed in and our of a MySQL stored
procedure through use of the `MySqlCommand.Parameters' collection.

*Note*:

When you call a stored procedure, the command object makes an
additional *Note `SELECT': select. call to determine the parameters of
the stored procedure. You must ensure that the user calling the
procedure has the `SELECT' privilege on the `mysql.proc' table to
enable them to verify the parameters. Failure to do this will result in
an error when calling the procedure.

This section will not provide in-depth information on creating Stored
Procedures. For such information, please refer to
`http://dev.mysql.com/doc/mysql/en/stored-routines.html'.

A sample application demonstrating how to use stored procedures with
Connector/NET can be found in the `Samples' directory of your
Connector/NET installation.


File: manual.info,  Node: connector-net-using-stored-creating,  Next: connector-net-using-stored-calling,  Prev: connector-net-using-stored-introduction,  Up: connector-net-using-stored

20.2.5.12 Creating Stored Procedures from Connector/NET
.......................................................

Stored procedures in MySQL can be created using a variety of tools.
First, stored procedures can be created using the *Note `mysql': mysql.
command-line client. Second, stored procedures can be created using the
`MySQL Query Browser' GUI client. Finally, stored procedures can be
created using the `.ExecuteNonQuery' method of the `MySqlCommand'
object:

Visual Basic Example

     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=test"

     Try
         conn.Open()
         cmd.Connection = conn

         cmd.CommandText = "CREATE PROCEDURE add_emp(" _
             & "IN fname VARCHAR(20), IN lname VARCHAR(20), IN bday DATETIME, OUT empno INT) " _
             & "BEGIN INSERT INTO emp(first_name, last_name, birthdate) " _
             & "VALUES(fname, lname, DATE(bday)); SET empno = LAST_INSERT_ID(); END"

         cmd.ExecuteNonQuery()
     Catch ex As MySqlException
         MessageBox.Show("Error " & ex.Number & " has occurred: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         conn.Open();
         cmd.Connection = conn;

         cmd.CommandText = "CREATE PROCEDURE add_emp(" +
             "IN fname VARCHAR(20), IN lname VARCHAR(20), IN bday DATETIME, OUT empno INT) " +
             "BEGIN INSERT INTO emp(first_name, last_name, birthdate) " +
             "VALUES(fname, lname, DATE(bday)); SET empno = LAST_INSERT_ID(); END";

         cmd.ExecuteNonQuery();
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
     MessageBox.Show("Error " + ex.Number + " has occurred: " + ex.Message,
         "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

It should be noted that, unlike the command-line and GUI clients, you
are not required to specify a special delimiter when creating stored
procedures in Connector/NET.


File: manual.info,  Node: connector-net-using-stored-calling,  Prev: connector-net-using-stored-creating,  Up: connector-net-using-stored

20.2.5.13 Calling a Stored Procedure from Connector/NET
.......................................................

To call a stored procedure using Connector/NET, create a `MySqlCommand'
object and pass the stored procedure name as the `.CommandText'
property. Set the `.CommandType' property to
`CommandType.StoredProcedure'.

After the stored procedure is named, create one `MySqlCommand'
parameter for every parameter in the stored procedure. `IN' parameters
are defined with the parameter name and the object containing the
value, `OUT' parameters are defined with the parameter name and the
datatype that is expected to be returned. All parameters need the
parameter direction defined.

After defining parameters, call the stored procedure by using the
`MySqlCommand.ExecuteNonQuery()' method:

Visual Basic Example

     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=test"

     Try
         conn.Open()
         cmd.Connection = conn

         cmd.CommandText = "add_emp"
         cmd.CommandType = CommandType.StoredProcedure

         cmd.Parameters.Add("@lname", 'Jones')
         cmd.Parameters["@lname"].Direction = ParameterDirection.Input

         cmd.Parameters.Add("@fname", 'Tom')
         cmd.Parameters["@fname"].Direction = ParameterDirection.Input

         cmd.Parameters.Add("@bday", #12/13/1977 2:17:36 PM#)
         cmd.Parameters["@bday"].Direction = ParameterDirection.Input

         cmd.Parameters.Add("@empno", MySqlDbType.Int32)
         cmd.Parameters["@empno"].Direction = ParameterDirection.Output

         cmd.ExecuteNonQuery()

         MessageBox.Show(cmd.Parameters["@empno"].Value)
     Catch ex As MySqlException
         MessageBox.Show("Error " & ex.Number & " has occurred: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         conn.Open();
         cmd.Connection = conn;

         cmd.CommandText = "add_emp";
         cmd.CommandType = CommandType.StoredProcedure;

         cmd.Parameters.Add("@lname", "Jones");
         cmd.Parameters["@lname"].Direction = ParameterDirection.Input;

         cmd.Parameters.Add("@fname", "Tom");
         cmd.Parameters["@fname"].Direction = ParameterDirection.Input;

         cmd.Parameters.Add("@bday", DateTime.Parse("12/13/1977 2:17:36 PM"));
         cmd.Parameters["@bday"].Direction = ParameterDirection.Input;

         cmd.Parameters.Add("@empno", MySqlDbType.Int32);
         cmd.Parameters["@empno"].Direction = ParameterDirection.Output;

         cmd.ExecuteNonQuery();

         MessageBox.Show(cmd.Parameters["@empno"].Value);
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show("Error " + ex.Number + " has occurred: " + ex.Message,
           "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

Once the stored procedure is called, the values of output parameters
can be retrieved by using the `.Value' property of the
`MySqlConnector.Parameters' collection.


File: manual.info,  Node: connector-net-using-blob,  Next: connector-net-using-crystal,  Prev: connector-net-using-stored,  Up: connector-net-using

20.2.5.14 Handling BLOB Data With Connector/NET
...............................................

* Menu:

* connector-net-using-blob-introduction::  Introduction
* connector-net-using-blob-serverprep::  Preparing the MySQL Server
* connector-net-using-blob-writing::  Writing a File to the Database
* connector-net-using-blob-reading::  Reading a BLOB from the Database to a File on Disk


File: manual.info,  Node: connector-net-using-blob-introduction,  Next: connector-net-using-blob-serverprep,  Prev: connector-net-using-blob,  Up: connector-net-using-blob

20.2.5.15 Introduction
......................

One common use for MySQL is the storage of binary data in *Note `BLOB':
blob. columns. MySQL supports four different BLOB datatypes: *Note
`TINYBLOB': blob, *Note `BLOB': blob, *Note `MEDIUMBLOB': blob, and
*Note `LONGBLOB': blob.

Data stored in a BLOB column can be accessed using Connector/NET and
manipulated using client-side code. There are no special requirements
for using Connector/NET with BLOB data.

Simple code examples will be presented within this section, and a full
sample application can be found in the `Samples' directory of the
Connector/NET installation.


File: manual.info,  Node: connector-net-using-blob-serverprep,  Next: connector-net-using-blob-writing,  Prev: connector-net-using-blob-introduction,  Up: connector-net-using-blob

20.2.5.16 Preparing the MySQL Server
....................................

The first step is using MySQL with BLOB data is to configure the
server. Let's start by creating a table to be accessed. In my file
tables, I usually have four columns: an AUTO_INCREMENT column of
appropriate size (UNSIGNED SMALLINT) to serve as a primary key to
identify the file, a VARCHAR column that stores the file name, an
UNSIGNED MEDIUMINT column that stores the size of the file, and a
MEDIUMBLOB column that stores the file itself. For this example, I will
use the following table definition:

     CREATE TABLE file(
     file_id SMALLINT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
     file_name VARCHAR(64) NOT NULL,
     file_size MEDIUMINT UNSIGNED NOT NULL,
     file MEDIUMBLOB NOT NULL);

After creating a table, you may need to modify the max_allowed_packet
system variable. This variable determines how large of a packet (i.e. a
single row) can be sent to the MySQL server. By default, the server
will only accept a maximum size of 1 meg from our client application.
If you do not intend to exceed 1 meg, this should be fine. If you do
intend to exceed 1 meg in your file transfers, this number has to be
increased.

The max_allowed_packet option can be modified using MySQL
Administrator's Startup Variables screen. Adjust the Maximum allowed
option in the Memory section of the Networking tab to an appropriate
setting. After adjusting the value, click the `Apply Changes' button
and restart the server using the `Service Control' screen of MySQL
Administrator. You can also adjust this value directly in the my.cnf
file (add a line that reads max_allowed_packet=xxM), or use the SET
max_allowed_packet=xxM; syntax from within MySQL.

Try to be conservative when setting max_allowed_packet, as transfers of
BLOB data can take some time to complete. Try to set a value that will
be adequate for your intended use and increase the value if necessary.


File: manual.info,  Node: connector-net-using-blob-writing,  Next: connector-net-using-blob-reading,  Prev: connector-net-using-blob-serverprep,  Up: connector-net-using-blob

20.2.5.17 Writing a File to the Database
........................................

To write a file to a database we need to convert the file to a byte
array, then use the byte array as a parameter to an *Note `INSERT':
insert. query.

The following code opens a file using a FileStream object, reads it
into a byte array, and inserts it into the `file' table:

Visual Basic Example

     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand

     Dim SQL As String

     Dim FileSize As UInt32
     Dim rawData() As Byte
     Dim fs As FileStream

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=test"

     Try
         fs = New FileStream("c:\image.png", FileMode.Open, FileAccess.Read)
         FileSize = fs.Length

         rawData = New Byte(FileSize) {}
         fs.Read(rawData, 0, FileSize)
         fs.Close()

         conn.Open()

         SQL = "INSERT INTO file VALUES(NULL, @FileName, @FileSize, @File)"

         cmd.Connection = conn
         cmd.CommandText = SQL
         cmd.Parameters.Add("@FileName", strFileName)
         cmd.Parameters.Add("@FileSize", FileSize)
         cmd.Parameters.Add("@File", rawData)

         cmd.ExecuteNonQuery()

         MessageBox.Show("File Inserted into database successfully!", _
         "Success!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)

         conn.Close()
     Catch ex As Exception
         MessageBox.Show("There was an error: " & ex.Message, "Error", _
             MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();

     string SQL;
     UInt32 FileSize;
     byte[] rawData;
     FileStream fs;

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         fs = new FileStream(@"c:\image.png", FileMode.Open, FileAccess.Read);
         FileSize = fs.Length;

         rawData = new byte[FileSize];
         fs.Read(rawData, 0, FileSize);
         fs.Close();

         conn.Open();

         SQL = "INSERT INTO file VALUES(NULL, @FileName, @FileSize, @File)";

         cmd.Connection = conn;
         cmd.CommandText = SQL;
         cmd.Parameters.Add("@FileName", strFileName);
         cmd.Parameters.Add("@FileSize", FileSize);
         cmd.Parameters.Add("@File", rawData);

         cmd.ExecuteNonQuery();

         MessageBox.Show("File Inserted into database successfully!",
             "Success!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);

         conn.Close();
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show("Error " + ex.Number + " has occurred: " + ex.Message,
             "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

The `Read' method of the `FileStream' object is used to load the file
into a byte array which is sized according to the `Length' property of
the FileStream object.

After assigning the byte array as a parameter of the `MySqlCommand'
object, the `ExecuteNonQuery' method is called and the BLOB is inserted
into the `file' table.


File: manual.info,  Node: connector-net-using-blob-reading,  Prev: connector-net-using-blob-writing,  Up: connector-net-using-blob

20.2.5.18 Reading a BLOB from the Database to a File on Disk
............................................................

Once a file is loaded into the `file' table, we can use the
`MySqlDataReader' class to retrieve it.

The following code retrieves a row from the `file' table, then loads
the data into a `FileStream' object to be written to disk:

Visual Basic Example

     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand
     Dim myData As MySqlDataReader
     Dim SQL As String
     Dim rawData() As Byte
     Dim FileSize As UInt32
     Dim fs As FileStream

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=test"

     SQL = "SELECT file_name, file_size, file FROM file"

     Try
         conn.Open()

         cmd.Connection = conn
         cmd.CommandText = SQL

         myData = cmd.ExecuteReader

         If Not myData.HasRows Then Throw New Exception("There are no BLOBs to save")

         myData.Read()

         FileSize = myData.GetUInt32(myData.GetOrdinal("file_size"))
         rawData = New Byte(FileSize) {}

         myData.GetBytes(myData.GetOrdinal("file"), 0, rawData, 0, FileSize)

         fs = New FileStream("C:\newfile.png", FileMode.OpenOrCreate, FileAccess.Write)
         fs.Write(rawData, 0, FileSize)
         fs.Close()

         MessageBox.Show("File successfully written to disk!", "Success!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)

         myData.Close()
         conn.Close()
     Catch ex As Exception
         MessageBox.Show("There was an error: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;
     MySql.Data.MySqlClient.MySqlDataReader myData;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();

     string SQL;
     UInt32 FileSize;
     byte[] rawData;
     FileStream fs;

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     SQL = "SELECT file_name, file_size, file FROM file";

     try
     {
         conn.Open();

         cmd.Connection = conn;
         cmd.CommandText = SQL;

         myData = cmd.ExecuteReader();

         if (! myData.HasRows)
             throw new Exception("There are no BLOBs to save");

         myData.Read();

         FileSize = myData.GetUInt32(myData.GetOrdinal("file_size"));
         rawData = new byte[FileSize];

         myData.GetBytes(myData.GetOrdinal("file"), 0, rawData, 0, FileSize);

         fs = new FileStream(@"C:\newfile.png", FileMode.OpenOrCreate, FileAccess.Write);
         fs.Write(rawData, 0, FileSize);
         fs.Close();

         MessageBox.Show("File successfully written to disk!",
             "Success!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);

         myData.Close();
         conn.Close();
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show("Error " + ex.Number + " has occurred: " + ex.Message,
             "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

After connecting, the contents of the `file' table are loaded into a
`MySqlDataReader' object. The `GetBytes' method of the MySqlDataReader
is used to load the BLOB into a byte array, which is then written to
disk using a FileStream object.

The `GetOrdinal' method of the MySqlDataReader can be used to determine
the integer index of a named column. Use of the GetOrdinal method
prevents errors if the column order of the *Note `SELECT': select.
query is changed.


File: manual.info,  Node: connector-net-using-crystal,  Next: connector-net-using-datetime,  Prev: connector-net-using-blob,  Up: connector-net-using

20.2.5.19 Using Connector/NET with Crystal Reports
..................................................

* Menu:

* connector-net-using-crystal-introduction::  Introduction
* connector-net-using-crystal-source::  Creating a Data Source
* connector-net-using-crystal-creating::  Creating the Report
* connector-net-using-crystal-displaying::  Displaying the Report


File: manual.info,  Node: connector-net-using-crystal-introduction,  Next: connector-net-using-crystal-source,  Prev: connector-net-using-crystal,  Up: connector-net-using-crystal

20.2.5.20 Introduction
......................

Crystal Reports is a common tool used by Windows application developers
to perform reporting and document generation. In this section we will
show how to use Crystal Reports XI with MySQL and Connector/NET.


File: manual.info,  Node: connector-net-using-crystal-source,  Next: connector-net-using-crystal-creating,  Prev: connector-net-using-crystal-introduction,  Up: connector-net-using-crystal

20.2.5.21 Creating a Data Source
................................

When creating a report in Crystal Reports there are two options for
accessing the MySQL data while designing your report.

The first option is to use Connector/ODBC as an ADO data source when
designing your report. You will be able to browse your database and
choose tables and fields using drag and drop to build your report. The
disadvantage of this approach is that additional work must be performed
within your application to produce a data set that matches the one
expected by your report.

The second option is to create a data set in VB.NET and save it as XML.
This XML file can then be used to design a report.  This works quite
well when displaying the report in your application, but is less
versatile at design time because you must choose all relevant columns
when creating the data set.  If you forget a column you must re-create
the data set before the column can be added to the report.

The following code can be used to create a data set from a query and
write it to disk:

Visual Basic Example

     Dim myData As New DataSet
     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand
     Dim myAdapter As New MySqlDataAdapter

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=world"

     Try
         conn.Open()
         cmd.CommandText = "SELECT city.name AS cityName, city.population AS CityPopulation, " _
             & "country.name, country.population, country.continent " _
             & "FROM country, city ORDER BY country.continent, country.name"
         cmd.Connection = conn

         myAdapter.SelectCommand = cmd
         myAdapter.Fill(myData)

         myData.WriteXml("C:\dataset.xml", XmlWriteMode.WriteSchema)
     Catch ex As Exception
         MessageBox.Show(ex.Message, "Report could not be created", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     DataSet myData = new DataSet();
     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;
     MySql.Data.MySqlClient.MySqlDataAdapter myAdapter;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();
     myAdapter = new MySql.Data.MySqlClient.MySqlDataAdapter();

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
       "pwd=12345;database=test;";

     try
     {
       cmd.CommandText = "SELECT city.name AS cityName, city.population AS CityPopulation, " +
       "country.name, country.population, country.continent " +
       "FROM country, city ORDER BY country.continent, country.name";
       cmd.Connection = conn;

       myAdapter.SelectCommand = cmd;
       myAdapter.Fill(myData);

       myData.WriteXml(@"C:\dataset.xml", XmlWriteMode.WriteSchema);
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
       MessageBox.Show(ex.Message, "Report could not be created",
       MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

The resulting XML file can be used as an ADO.NET XML datasource when
designing your report.

If you choose to design your reports using Connector/ODBC, it can be
downloaded from dev.mysql.com
(http://dev.mysql.com/downloads/connector/odbc/3.51.html).


File: manual.info,  Node: connector-net-using-crystal-creating,  Next: connector-net-using-crystal-displaying,  Prev: connector-net-using-crystal-source,  Up: connector-net-using-crystal

20.2.5.22 Creating the Report
.............................

For most purposes the Standard Report wizard should help with the
initial creation of a report. To start the wizard, open Crystal Reports
and choose the New > Standard Report option from the File menu.

The wizard will first prompt you for a data source. If you are using
Connector/ODBC as your data source, use the OLEDB provider for ODBC
option from the OLE DB (ADO) tree instead of the ODBC (RDO) tree when
choosing a data source. If using a saved data set, choose the ADO.NET
(XML) option and browse to your saved data set.

The remainder of the report creation process is done automatically by
the wizard.

After the report is created, choose the Report Options...  entry of the
File menu. Un-check the Save Data With Report option. This prevents
saved data from interfering with the loading of data within our
application.


File: manual.info,  Node: connector-net-using-crystal-displaying,  Prev: connector-net-using-crystal-creating,  Up: connector-net-using-crystal

20.2.5.23 Displaying the Report
...............................

To display a report we first populate a data set with the data needed
for the report, then load the report and bind it to the data set.
Finally we pass the report to the crViewer control for display to the
user.

The following references are needed in a project that displays a report:

   * CrytalDecisions.CrystalReports.Engine

   * CrystalDecisions.ReportSource

   * CrystalDecisions.Shared

   * CrystalDecisions.Windows.Forms

The following code assumes that you created your report using a data
set saved using the code shown in *Note
connector-net-using-crystal-source::, and have a crViewer control on
your form named `myViewer'.

Visual Basic Example

     Imports CrystalDecisions.CrystalReports.Engine
     Imports System.Data
     Imports MySql.Data.MySqlClient

     Dim myReport As New ReportDocument
     Dim myData As New DataSet
     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand
     Dim myAdapter As New MySqlDataAdapter

     conn.ConnectionString = _
         "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=test"

     Try
         conn.Open()

         cmd.CommandText = "SELECT city.name AS cityName, city.population AS CityPopulation, " _
             & "country.name, country.population, country.continent " _
             & "FROM country, city ORDER BY country.continent, country.name"
         cmd.Connection = conn

         myAdapter.SelectCommand = cmd
         myAdapter.Fill(myData)

         myReport.Load(".\world_report.rpt")
         myReport.SetDataSource(myData)
         myViewer.ReportSource = myReport
     Catch ex As Exception
         MessageBox.Show(ex.Message, "Report could not be created", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     using CrystalDecisions.CrystalReports.Engine;
     using System.Data;
     using MySql.Data.MySqlClient;

     ReportDocument myReport = new ReportDocument();
     DataSet myData = new DataSet();
     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;
     MySql.Data.MySqlClient.MySqlDataAdapter myAdapter;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();
     myAdapter = new MySql.Data.MySqlClient.MySqlDataAdapter();

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         cmd.CommandText = "SELECT city.name AS cityName, city.population AS CityPopulation, " +
             "country.name, country.population, country.continent " +
             "FROM country, city ORDER BY country.continent, country.name";
         cmd.Connection = conn;

         myAdapter.SelectCommand = cmd;
         myAdapter.Fill(myData);

         myReport.Load(@".\world_report.rpt");
         myReport.SetDataSource(myData);
         myViewer.ReportSource = myReport;
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show(ex.Message, "Report could not be created",
             MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

A new data set it generated using the same query used to generate the
previously saved data set. Once the data set is filled, a
ReportDocument is used to load the report file and bind it to the data
set. The ReportDocument is the passed as the ReportSource of the
crViewer.

This same approach is taken when a report is created from a single
table using Connector/ODBC. The data set replaces the table used in the
report and the report is displayed properly.

When a report is created from multiple tables using Connector/ODBC, a
data set with multiple tables must be created in our application. This
allows each table in the report data source to be replaced with a
report in the data set.

We populate a data set with multiple tables by providing multiple *Note
`SELECT': select. statements in our MySqlCommand object. These *Note
`SELECT': select. statements are based on the SQL query shown in
Crystal Reports in the Database menu's Show SQL Query option. Assume
the following query:

     SELECT `country`.`Name`, `country`.`Continent`, `country`.`Population`, `city`.`Name`, `city`.`Population`
     FROM `world`.`country` `country` LEFT OUTER JOIN `world`.`city` `city` ON `country`.`Code`=`city`.`CountryCode`
     ORDER BY `country`.`Continent`, `country`.`Name`, `city`.`Name`

This query is converted to two *Note `SELECT': select. queries and
displayed with the following code:

Visual Basic Example

     Imports CrystalDecisions.CrystalReports.Engine
     Imports System.Data
     Imports MySql.Data.MySqlClient

     Dim myReport As New ReportDocument
     Dim myData As New DataSet
     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand
     Dim myAdapter As New MySqlDataAdapter

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=world"

     Try
         conn.Open()
         cmd.CommandText = "SELECT name, population, countrycode FROM city ORDER BY countrycode, name; " _
             & "SELECT name, population, code, continent FROM country ORDER BY continent, name"
         cmd.Connection = conn

         myAdapter.SelectCommand = cmd
         myAdapter.Fill(myData)

         myReport.Load(".\world_report.rpt")
         myReport.Database.Tables(0).SetDataSource(myData.Tables(0))
         myReport.Database.Tables(1).SetDataSource(myData.Tables(1))
         myViewer.ReportSource = myReport
     Catch ex As Exception
         MessageBox.Show(ex.Message, "Report could not be created", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     using CrystalDecisions.CrystalReports.Engine;
     using System.Data;
     using MySql.Data.MySqlClient;

     ReportDocument myReport = new ReportDocument();
     DataSet myData = new DataSet();
     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;
     MySql.Data.MySqlClient.MySqlDataAdapter myAdapter;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();
     myAdapter = new MySql.Data.MySqlClient.MySqlDataAdapter();

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         cmd.CommandText = "SELECT name, population, countrycode FROM city ORDER " +
             "BY countrycode, name; *Note `SELECT': select. name, population, code, continent FROM " +
             "country ORDER BY continent, name";
         cmd.Connection = conn;

         myAdapter.SelectCommand = cmd;
         myAdapter.Fill(myData);

         myReport.Load(@".\world_report.rpt");
         myReport.Database.Tables(0).SetDataSource(myData.Tables(0));
         myReport.Database.Tables(1).SetDataSource(myData.Tables(1));
         myViewer.ReportSource = myReport;
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show(ex.Message, "Report could not be created",
             MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

It is important to order the *Note `SELECT': select. queries in
alphabetical order, as this is the order the report will expect its
source tables to be in. One SetDataSource statement is needed for each
table in the report.

This approach can cause performance problems because Crystal Reports
must bind the tables together on the client-side, which will be slower
than using a pre-saved data set.


File: manual.info,  Node: connector-net-using-datetime,  Next: connector-net-using-faq,  Prev: connector-net-using-crystal,  Up: connector-net-using

20.2.5.24 Handling Date and Time Information in Connector/NET
.............................................................

* Menu:

* connector-net-using-datetime-introduction::  Introduction
* connector-net-using-datetime-problems::  Problems when Using Invalid Dates
* connector-net-using-datetime-restricting::  Restricting Invalid Dates
* connector-net-using-datetime-invalid::  Handling Invalid Dates
* connector-net-using-datetime-null::  Handling NULL Dates


File: manual.info,  Node: connector-net-using-datetime-introduction,  Next: connector-net-using-datetime-problems,  Prev: connector-net-using-datetime,  Up: connector-net-using-datetime

20.2.5.25 Introduction
......................

MySQL and the .NET languages handle date and time information
differently, with MySQL allowing dates that cannot be represented by a
.NET data type, such as '`0000-00-00 00:00:00''. These differences can
cause problems if not properly handled.

In this section we will demonstrate how to properly handle date and
time information when using Connector/NET.


File: manual.info,  Node: connector-net-using-datetime-problems,  Next: connector-net-using-datetime-restricting,  Prev: connector-net-using-datetime-introduction,  Up: connector-net-using-datetime

20.2.5.26 Problems when Using Invalid Dates
...........................................

The differences in date handling can cause problems for developers who
use invalid dates. Invalid MySQL dates cannot be loaded into native
.NET `DateTime' objects, including `NULL' dates.

Because of this issue, .NET `DataSet' objects cannot be populated by
the `Fill' method of the `MySqlDataAdapter' class as invalid dates will
cause a `System.ArgumentOutOfRangeException' exception to occur.


File: manual.info,  Node: connector-net-using-datetime-restricting,  Next: connector-net-using-datetime-invalid,  Prev: connector-net-using-datetime-problems,  Up: connector-net-using-datetime

20.2.5.27 Restricting Invalid Dates
...................................

The best solution to the date problem is to restrict users from
entering invalid dates. This can be done on either the client or the
server side.

Restricting invalid dates on the client side is as simple as always
using the .NET `DateTime' class to handle dates. The `DateTime' class
will only allow valid dates, ensuring that the values in your database
are also valid. The disadvantage of this is that it is not useful in a
mixed environment where .NET and non .NET code are used to manipulate
the database, as each application must perform its own date validation.

Users of MySQL 5.0.2 and higher can use the new `traditional' SQL mode
to restrict invalid date values. For information on using the
`traditional' SQL mode, see *Note server-sql-mode::.


File: manual.info,  Node: connector-net-using-datetime-invalid,  Next: connector-net-using-datetime-null,  Prev: connector-net-using-datetime-restricting,  Up: connector-net-using-datetime

20.2.5.28 Handling Invalid Dates
................................

Although it is strongly recommended that you avoid the use of invalid
dates within your .NET application, it is possible to use invalid dates
by means of the `MySqlDateTime' datatype.

The `MySqlDateTime' datatype supports the same date values that are
supported by the MySQL server. The default behavior of Connector/NET is
to return a .NET DateTime object for valid date values, and return an
error for invalid dates. This default can be modified to cause
Connector/NET to return `MySqlDateTime' objects for invalid dates.

To instruct Connector/NET to return a `MySqlDateTime' object for
invalid dates, add the following line to your connection string:

       Allow Zero Datetime=True

Please note that the use of the `MySqlDateTime' class can still be
problematic. The following are some known issues:

  1. Data binding for invalid dates can still cause errors (zero dates
     like 0000-00-00 do not seem to have this problem).

  2. The `ToString' method return a date formatted in the standard
     MySQL format (for example, `2005-02-23 08:50:25'). This differs
     from the `ToString' behavior of the .NET DateTime class.

  3. The `MySqlDateTime' class supports NULL dates, while the .NET
     DateTime class does not. This can cause errors when trying to
     convert a MySQLDateTime to a DateTime if you do not check for NULL
     first.

Because of the known issues, the best recommendation is still to use
only valid dates in your application.


File: manual.info,  Node: connector-net-using-datetime-null,  Prev: connector-net-using-datetime-invalid,  Up: connector-net-using-datetime

20.2.5.29 Handling NULL Dates
.............................

The .NET `DateTime' datatype cannot handle `NULL' values. As such, when
assigning values from a query to a `DateTime' variable, you must first
check whether the value is in fact `NULL'.

When using a `MySqlDataReader', use the `.IsDBNull' method to check
whether a value is `NULL' before making the assignment:

Visual Basic Example

     If Not myReader.IsDBNull(myReader.GetOrdinal("mytime")) Then
         myTime = myReader.GetDateTime(myReader.GetOrdinal("mytime"))
     Else
         myTime = DateTime.MinValue
     End If

C# Example

     if (! myReader.IsDBNull(myReader.GetOrdinal("mytime")))
         myTime = myReader.GetDateTime(myReader.GetOrdinal("mytime"));
     else
         myTime = DateTime.MinValue;

`NULL' values will work in a data set and can be bound to form controls
without special handling.


File: manual.info,  Node: connector-net-using-faq,  Prev: connector-net-using-datetime,  Up: connector-net-using

20.2.5.30 Frequently Asked Questions
....................................

The following details a number of frequently asked questions about
Connector/NET.

*Questions*
   * 20.2.5.8.1: How do I obtain the value of an auto-incremented
     column?

*Questions and Answers* *20.2.5.8.1: ** How do I obtain the value of an
auto-incremented column?  *

When using the commandBuilder you should make sure that you set the
`ReturnGeneratedIdentifiers' property to `true'.

Then, you can use an active view on a table to access the updated ID.
For example:

            conn = new MySql.Data.MySqlClient.MySqlConnection();
            cmd = new MySql.Data.MySqlClient.MySqlCommand();
            da = new MySql.Data.MySqlClient.MySqlDataAdapter();
            cmdBuilder = new MySql.Data.MySqlClient.MySqlCommandBuilder();
            SystemDataDataSet = new System.Data.DataSet();
            SystemDataDataView = new System.Data.DataView();
     ...
             cmd.Connection = conn;
             cmd.CommandText = "SELECT * FROM contacts";
     			  da.SelectCommand = cmd;
             da.Fill(SystemDataDataSet, "contacts");
     				cmdBuilder.DataAdapter = da;
             cmdBuilder.ReturnGeneratedIdentifiers = true;
             cmdBuilder.DataAdapter.SelectCommand.CommandText = "SELECT * FROM contacts";
     				cmdBuilder.RefreshSchema();

             SystemDataDataView = SystemDataDataSet.Tables["contacts"].DefaultView;

     				SystemDataDataRow = SystemDataDataView.Table.NewRow();
             SystemDataDataRow["status"] = 1;

             SystemDataDataView.Table.Rows.Add(SystemDataDataRow);
             da.Update(SystemDataDataSet, "contacts");
             System.Console.WriteLine("ID after update: "  + SystemDataDataRow["id"]);

The `SystemDataDataRow' object in this instance provides the interface
to the updated auto-increment value in the `id' column.


File: manual.info,  Node: connect-net-support,  Prev: connector-net-using,  Up: connector-net

20.2.6 Connector/NET Support
----------------------------

* Menu:

* connector-net-support-community::  Connector/NET Community Support
* connector-net-support-bug-report::  How to report Connector/NET Problems or Bugs
* connector-net-support-changehistory::  Connector/NET Change History

The developers of Connector/NET greatly value the input of our users in
the software development process. If you find Connector/NET lacking
some feature important to you, or if you discover a bug and need to
file a bug report, please use the instructions in *Note bug-reports::.


File: manual.info,  Node: connector-net-support-community,  Next: connector-net-support-bug-report,  Prev: connect-net-support,  Up: connect-net-support

20.2.6.1 Connector/NET Community Support
........................................

   * Community support for Connector/NET can be found through the
     forums at `http://forums.mysql.com'.

   * Community support for Connector/NET can also be found through the
     mailing lists at `http://lists.mysql.com'.

   * Paid support is available from Sun Microsystems, Inc.  Additional
     information is available at `http://www.mysql.com/support/'.


File: manual.info,  Node: connector-net-support-bug-report,  Next: connector-net-support-changehistory,  Prev: connector-net-support-community,  Up: connect-net-support

20.2.6.2 How to report Connector/NET Problems or Bugs
.....................................................

If you encounter difficulties or problems with Connector/NET, contact
the Connector/NET community *Note connector-net-support-community::.

You should first try to execute the same SQL statements and commands
from the *Note `mysql': mysql. client program or from `admndemo'. This
helps you determine whether the error is in Connector/NET or MySQL.

If reporting a problem, you should ideally include the following
information with the email:

   * Operating system and version

   * Connector/NET version

   * MySQL server version

   * Copies of error messages or other unexpected output

   * Simple reproducible sample

Remember that the more information you can supply to us, the more
likely it is that we can fix the problem.

If you believe the problem to be a bug, then you must report the bug
through `http://bugs.mysql.com/'.


File: manual.info,  Node: connector-net-support-changehistory,  Prev: connector-net-support-bug-report,  Up: connect-net-support

20.2.6.3 Connector/NET Change History
.....................................

The Connector/NET Change History (Changelog) is located with the main
Changelog for MySQL. See *Note connector-net-news::.


File: manual.info,  Node: connector-vstudio,  Next: connector-j,  Prev: connector-net,  Up: connectors-apis

20.3 MySQL Visual Studio Plugin
===============================

* Menu:

* connector-vstudio-install::    Installing the MySQL Visual Studio Plugin
* connector-vstudio-creating::   Creating a connection to the MySQL server
* connector-vstudio-using::      Using the MySQL Visual Studio Plugin
* connector-vstudio-support::    Visual Studio Plugin Support

The MySQL Visual Studio Plugin is a DDEX provider; a plug-in for Visual
Studio 2005 that allows developers to maintain database structures, and
supports built-in data-driven application development tools.

The current version of the MySQL Visual Studio Plugin includes only
database maintenance tools. Data-driven application development tools
are not supported.

The MySQL DDEX Provider operates as a standard extension to the Visual
Studio Data Designer functionality available through the Server
Explorer menu of Visual Studio 2005, and enables developers to create
database objects and data within a MySQL database.

The MySQL Visual Studio Plugin is designed to work with MySQL version
5.0, but is also compatible with MySQL 4.1.1 and provides limited
compatibility with MySQL 5.1.


File: manual.info,  Node: connector-vstudio-install,  Next: connector-vstudio-creating,  Prev: connector-vstudio,  Up: connector-vstudio

20.3.1 Installing the MySQL Visual Studio Plugin
------------------------------------------------

The MySQL Visual Studio Plugin requires one of Visual Studio 2005
Standard, Professional or Team Developer Edition to be installed.
Other editions of Visual Studio 2005 are not supported.

*Note*:

Starting with Connector/NET 5.1.2, the Visual Studio Plugin is included
in the installation. If you have installed Connector/NET 5.1.2, then
you do not need to separately install the Visual Studio Plugin.

Here is the list of components that should already be installed before
starting the installation of the MySQL Visual Studio Plugin:

   * Visual Studio 2005 Standard, Professional or Team Developer
     Edition.

   * MySQL Server 4.1.1 or later (either installed on the same machine,
     or a separate server).

   * MySQL Connector/NET 5.0.

*Note*:

When installing Connector/NET you must ensure that the connector is
installed into the Global Assembly Cache (GAC). The Connector/NET
installer handles this for you automatically, but in a custom
installation the option may have been disabled.

The user used to connect to the MySQL server must have the following
privileges to use the functionality provided by the MySQL Visual Studio
Plugin:

   * The `SELECT' privilege for the `INFORMATION_SCHEMA' database.

   * The *Note `EXECUTE': execute. privilege for the *Note `SHOW CREATE
     TABLE': show-create-table. statement.

   * The `SELECT' privilege for the `mysql.proc' table (required for
     operations with stored procedures and functions).

   * The `SELECT' privilege for the `mysql.func' table (required for
     operations with User Defined Functions (UDF)).

   * The *Note `EXECUTE': execute. privilege for the *Note `SHOW ENGINE
     STATUS': show-engine. statement (required for retrieving extended
     error information).

   * Appropriate privileges for performed operations (e.g. the `SELECT'
     privilege is required to browse data from a table etc.).

The MySQL Visual Studio Plugin is delivered as a MSI package that can
be used to install, uninstall or reinstall the Provider. If you are not
using Windows XP or Windows Server 2003 you upgrade the Windows
Installer system to the latest version (see
http://support.microsoft.com/default.aspx?scid=kb;EN-US;292539
(http://support.microsoft.com/default.aspx?scid=kb;EN-US;292539) for
details).

The MSI-package is named `MySQL.VisualStudio.msi'. To install the MySQL
Visual Studio Plugin, right click on the MSI file and select `Install'.
The installation process is as follow:

  1. The standard Welcome dialog is opened. Click Next to continue
     installation.

  2. The License agreement (GNU GPL) window is opened. Accept the
     agreement and click `Next' to continue.

  3. The destination folder choice dialog is opened. Here you can point
     out the folder where the MySQL Visual Studio Plugin will be
     installed. The default destination folder is
     `%ProgramFilesDir%\MySQL\MySQL DDEX Data Provider', where
     `%ProgramFilesDir%' is the Program Files folder of the
     installation machine. After choosing the destination folder, click
     `Next' to continue.

  4. The installer will ask to confirm that installation. Click Install
     to start installation process.

  5. The installation will now take place. At the end of this step the
     Visual Studio command table is rebuilt (this process may take
     several minutes).

  6. Once installation is complete, click `Finish' to end the
     installation process.

To uninstall the MySQL Visual Studio Plugin, you can use either
Add/Remove Programs component of the Control Panel or the same
MSI-package. Choose the `Remove' option, and the Provider will be
uninstalled automatically.

To repair the Provider, right click the MSI-package and choose the
`Repair' option. The MySQL Visual Studio Plugin will be repaired
automatically.

The installation package includes the following files:

   * `MySQL.VisualStudio.dll' -- the MySQL DDEX Provider assembly.

   * `MySQL.Data.dll' -- the assembly containing the MySQL Connector
     .NET which is used by the Provider.

   * `MySql.VisualStudio.dll.config' -- the configuration file for the
     MySQL Visual Studio Plugin. This file contains default values for
     the provider GUI layout.

     *Note*:

     Do not remove this file before the first use of the Provider.

   * `Register.reg' -- the file with registry entries that can be used
     to register the MySQL DDEX Provider in the case of the manual
     installation.

   * `Install.js' -- the script used to register the Connector .NET as
     an ADO.NET data provider in the machine.config file.

   * `Release notes.doc' -- the document with release notes.

To install the Provider manually, copy all files of the installation
package in a desired folder, then set the full path to the Provider
assembly as a value of the CodeBase entry. For example:

     [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\VisualStudio\8.0\Packages\{79A115C9-B133-4891-9E7B-242509DAD272}]@="MySql.Data.VisualStudio.MySqlDataProviderPackage"
     "InprocServer32"="C:\\WINNT\\system32\\mscoree.dll"
     "Class"="MySql.Data.VisualStudio.MySqlDataProviderPackage"
     "CodeBase"="C:\\MySqlDdexProvider\\MySql.VisualStudio.dll"

Then import information from the Register.reg file to the registry by
clicking of the file. At the confirmation dialog choose Yes.  Next you
must run the command devenv.exe /setup within a Command Prompt to
rebuild the Visual Studio command table.


File: manual.info,  Node: connector-vstudio-creating,  Next: connector-vstudio-using,  Prev: connector-vstudio-install,  Up: connector-vstudio

20.3.2 Creating a connection to the MySQL server
------------------------------------------------

Once the MySQL Visual Studio Plugin is installed, you can use it to
create, modify and delete connections to MySQL databases. To create a
connection with a MySQL database, perform the following steps:

  1. Start Visual Studio 2005 and open Server Explorer window by
     choosing the `Server Explorer' option from the `View' menu.

  2. Right click on the `Data Connections' node and choose the `Add
     Connection' button.

  3. The Add Connection dialog is opened. Press the `Change' button to
     choose MySQL Database as a data source.

  4. Change Data Source dialog is opened. Choose MySQL Database in the
     list of data sources (or the `other' option, if MySQL Database is
     absent), and then choose `.NET Framework Data Provider for MySQL'
     in the combo box of data providers.

     Choosing a data source

     Press `OK' to confirm your choice.

  5. Enter the connection settings: the server host name (for example,
     localhost if the MySQL server is installed on the local machine),
     the user name, the password, and the default database schema. Note
     that you must specify the default schema name to open the
     connection.

     Setting connection properties

  6. You can also set the port to connect with the MySQL server by
     pressing the `Advanced' button. To test a connection with the
     MySQL server, ser the server host name, the user name, and the
     password, and press the `Test Connection' button. If the test
     fails, check the connection values that you have supplied are
     correct and that the corresponding user and privileges have been
     configured on the MySQL server.

  7. After you set all settings and test the connection, press `OK'.
     The newly created connection is displayed in Server Explorer. Now
     you can work with the MySQL server through standard Server
     Explorer interface.

After a connection is successfully established, all the connection
settings are saved. When you next open Visual Studio, the connection to
the MySQL server will appear within Server Explorer so that you can
re-establish a connection to the MySQL server.

To modify and delete a connection, use the `Server Explorer' context
menu for the corresponding node. You can modify any of the settings
just by overwriting the existing values with new ones. Note that a
connection should be modified or deleted only if no active editor for
its objects is opened.  Otherwise your data could be lost.


File: manual.info,  Node: connector-vstudio-using,  Next: connector-vstudio-support,  Prev: connector-vstudio-creating,  Up: connector-vstudio

20.3.3 Using the MySQL Visual Studio Plugin
-------------------------------------------

* Menu:

* connector-vstudio-using-tables::  Editing Tables
* connector-vstudio-using-tabledata::  Editing Table Data
* connector-vstudio-using-views::  Editing Views
* connector-vstudio-using-storedroutines::  Editing Stored Procedures and Functions
* connector-vstudio-using-triggers::  Editing Triggers
* connector-vstudio-using-udf::  Editing User Defined Functions (UDF)
* connector-vstudio-using-dropping::  Dropping database objects
* connector-vstudio-using-cloning::  Cloning database objects

To work with a MySQL server using the MySQL Visual Studio Plugin, open
the Visual Studio 2005, open the `Server Explorer', and select the
required connection. The working area of the MySQL Visual Studio Plugin
consists of three parts.

DDEX enviroment

   * Database objects (tables, views, stored routines, triggers, and
     user defined functions) are displayed in the Server Explorer tree.
     Here you can choose an object and edit its properties and
     definition.

   * Properties of a selected database object are displayed in the
     `Properties' panel. Certain properties can be edited directly
     within this window.

   * The editor panel provides direct access to the SQL statement and
     definition of specific objects. Fore example, the SQL statements
     within a stored procedure definition are shown and edited within
     this panel.


File: manual.info,  Node: connector-vstudio-using-tables,  Next: connector-vstudio-using-tabledata,  Prev: connector-vstudio-using,  Up: connector-vstudio-using

20.3.3.1 Editing Tables
.......................

* Menu:

* connector-vstudio-using-tables-columns::  Column Editor
* connector-vstudio-using-tables-indexes::  Indexes tab
* connector-vstudio-using-tables-foreignkeys::  Foreign Keys tab
* connector-vstudio-using-tables-column::  Column Details tab
* connector-vstudio-using-tables-properties::  Table Properties window

The Table Editor can be accessed through a mouse action on table-type
node of Server Explorer. To create a new table, right click on the
`Tables' node (under the connection node) and choose the `Create Table'
command from a context menu. To modify an existing table, double click
on a node of the table you wish to modify, or right click on this node
and choose the `Alter Table' command from a context menu. Either of the
commands opens the Table Editor.

Editing a table

The MySQL Visual Studio Plugin Table Editor is implemented in a similar
fashion to the standard Query Browser Table Editor, but with minor
differences.

The Table Editor consists of the following parts:

   * Columns Editor -- for column creation, modification and deletion.

   * Indexes tab -- for table/column index management.

   * Foreign Keys tab -- for configuration of foreign keys.

   * Column Details tab -- used to set advanced column options.

   * Properties window -- used to set table properties.

To save changes you have made in the Table Editor, use either Save or
Save All buttons of the Visual Studio main toolbar, or just press
`Ctrl+S'. Before changes are saved, a confirmation dialog will be
displayed to confirm that you want to update the corresponding object
within the MySQL database.


File: manual.info,  Node: connector-vstudio-using-tables-columns,  Next: connector-vstudio-using-tables-indexes,  Prev: connector-vstudio-using-tables,  Up: connector-vstudio-using-tables

20.3.3.2 Column Editor
......................

You can use the Column Editor to set or change the name, data type,
default value and other properties of a table column. To set the
properties of an individual column, select the column using the mouse.
Alternatively, you can move through the grid using `Tab' and `Shift+Tab'
keys.

   * To set or change the name, data type, default value and comment of
     a column, select the appropriate cell and edit the desired value.

   * To set or unset flag-type column properties (i.e., primary key,
     `NOT NULL', auto-incremented, flags), check or uncheck the
     corresponding checkboxes.  Note that the available column flags
     will depend on the columns data type.

   * To reorder columns, index columns or foreign key columns in the
     Column Editor, select the whole column you wish to reorder by
     clicking on the selector column at the left of the column grid.
     Then move the column by using `Ctrl+Up' (to move the column up) and
     `Ctrl+Down' (to move the column down) keys.

   * To delete a column, select it by clicking on the selector column
     at the left of the column grid, then press the `Delete' button on
     a keyboard.


File: manual.info,  Node: connector-vstudio-using-tables-indexes,  Next: connector-vstudio-using-tables-foreignkeys,  Prev: connector-vstudio-using-tables-columns,  Up: connector-vstudio-using-tables

20.3.3.3 Indexes tab
....................

Index management is performed via the Indexes tab.

   * To add an index, press the `+' button and set the properties in
     the `Index Settings' groupbox at the right. You can set the index
     name, index kind, index type and a set of index columns.

   * To remove an index, select the index from the list and press the
     `-' button.

   * To change index settings, select the index from the list; detailed
     information about the index is displayed in the `Index Settings'
     panel.

You cannot change a table column to an index column using drag and
drop. Instead, you can add new index columns to a table and set their
table columns by using the embedded editor within the Indexes tab


File: manual.info,  Node: connector-vstudio-using-tables-foreignkeys,  Next: connector-vstudio-using-tables-column,  Prev: connector-vstudio-using-tables-indexes,  Up: connector-vstudio-using-tables

20.3.3.4 Foreign Keys tab
.........................

Foreign Key management is performed via the Foreign Keys tab.

   * To add a foreign key, press the `+' button and set properties in
     the `Foreign Keys Settings' panel. You can set the foreign key
     name, referenced table name, foreign key columns and actions on
     update and delete.

   * To remove a foreign key, select the foreign key and press the `-'
     button.

   * To change foreign key settings, select the foreign key and use the
     `Foreign Keys Settings' panel to edit the properties.

   * When a foreign key is changed, the MySQL Visual Studio Plugin
     generates two queries: the first query drops the changed keys and
     the second one recreates the new values.  The reason for such a
     behavior is to avoid the Bug#8377 (http://bugs.mysql.com/8377) and
     Bug#8919 (http://bugs.mysql.com/8919).

*Note*:

If changed values are for some reason inconsistent and cause the second
query to fail, all affected foreign keys will be dropped. If this is
the case, the MySQL Visual Studio Plugin will mark them as new in the
Table Editor, and you will have to recreate them later. But if you
close the Table Editor without saving, these foreign keys will be lost.


File: manual.info,  Node: connector-vstudio-using-tables-column,  Next: connector-vstudio-using-tables-properties,  Prev: connector-vstudio-using-tables-foreignkeys,  Up: connector-vstudio-using-tables

20.3.3.5 Column Details tab
...........................

The Column Details tab can be used to set column options.  Besides the
main column properties that are presented in the Column Editor, in the
Column Details tab you can set two additional properties options: the
character set and the collation sequence.


File: manual.info,  Node: connector-vstudio-using-tables-properties,  Prev: connector-vstudio-using-tables-column,  Up: connector-vstudio-using-tables

20.3.3.6 Table Properties window
................................

There is no separate tab for table options and advanced options. All
table options can be browsed and changed using the `Properties' window
of Visual Studio 2005.

The following table properties can be set:

   * ` Auto Increment'

   * ` Average Row Length'

   * ` Character Set'

   * ` Checksum for Rows'

   * ` Collation'

   * ` Comment'

   * ` Connection'

   * ` Data Directory'

   * ` Delay Key Updates'

   * ` Engine'

   * ` Index Directory'

   * ` Insert Method'

   * ` Maximum Rows'

   * ` Minimum Rows'

   * ` Name'

   * ` Pack Keys'

   * ` Password'

   * `Row Format'

   * `Union'

Some of these properties can have arbitrary text values, others accept
values from a predefined set.

The properties `Schema' and `Server' are read only.


File: manual.info,  Node: connector-vstudio-using-tabledata,  Next: connector-vstudio-using-views,  Prev: connector-vstudio-using-tables,  Up: connector-vstudio-using

20.3.3.7 Editing Table Data
...........................

The Table Data Editor, allows a user to browse, create and edit data of
tables. The Table Data Editor is implemented as a simple data grid with
auto generated columns.

To access the Table Data Editor, right click on a node representing the
table or view in Server Explorer. From the nodes context menu, choose
the `Browse' or `Edit Data' command. For tables and updatable views,
this command opens the Table Data Editor in edit mode.  For
non-updatable views, this command opens the Table Data Editor in
read-only mode.

When in the edit mode, you can modify table data by modifying the
displayed table contents directly. To add a row, set desired values in
the last row of the grid. To modify values, set new values in
appropriate cells. To delete a row, select it by clicking on the
selector column at the left of the grid, then press the `Delete' button.

To save changes you have made in the Table Data Editor, use either
`Save' or `Save All' buttons of the Visual Studio main toolbar, or just
press `Ctrl+S'. A confirmation dialog will confirm whether you want the
changes saved to the database.


File: manual.info,  Node: connector-vstudio-using-views,  Next: connector-vstudio-using-storedroutines,  Prev: connector-vstudio-using-tabledata,  Up: connector-vstudio-using

20.3.3.8 Editing Views
......................

To create a new view, right click the Views node under the connection
node in Server Explorer. From the nodes context menu, choose the
`Create View' command. This command opens the SQL Editor.

To modify an existing view, double click on a node of the view you wish
to modify, or right click on this node and choose the `Alter View'
command from a context menu.  Either of the commands opens the SQL
Editor.

To create or alter the view definition using SQL Editor, type the
appropriate SQL statement in the SQL Editor.

*Note*:

You should enter only the defining statement itself, without the `
CREATE VIEW AS' preface.

All other view properties can be set in the `Properties' window. These
properties are:

   * `Algorithm'

   * ` Check Option'

   * `Definer'

   * `Name'

   * `Security Type'

Some of these properties can have arbitrary text values, others accept
values from a predefined set.

The properties `Is Updatable', `Schema' and `Server' are readonly.

To save changes you have made, use either `Save' or `Save All' buttons
of the Visual Studio main toolbar, or just press `Ctrl+S'. A
confirmation dialog will confirm whether you want the changes saved to
the database.


File: manual.info,  Node: connector-vstudio-using-storedroutines,  Next: connector-vstudio-using-triggers,  Prev: connector-vstudio-using-views,  Up: connector-vstudio-using

20.3.3.9 Editing Stored Procedures and Functions
................................................

To create a new stored procedure, right click the Stored Procedures
node under the connection node in Server Explorer.  From the nodes
context menu, choose the `Create Routine' command. This command opens
the SQL Editor.

To create a new stored function, right click the `Functions' node under
the connection node in Server Explorer. From the node's context menu,
choose the `Create Routine' command.

To modify an existing stored routine (procedure or function), double
click on a node of the routine you wish to modify, or right click on
this node and choose the `Alter Routine 'command from a context menu.
Either of the commands opens the SQL Editor.

To create or alter the routine definition using SQL Editor, type this
definition in the SQL Editor using standard SQL.

All other routine properties can be set in the `Properties' window.
These properties are:

   * Comment

   * Data Access

   * Definer

   * Is Deterministic

   * Security Type

Some of these properties can have arbitrary text values, others accept
values only from a predefined set.

Also you can set all the options directly in the SQL Editor, using the
standard *Note `CREATE PROCEDURE': create-procedure. or *Note `CREATE
FUNCTION': create-function. statement. However, it is recommended to use
the `Properties' window instead.

*Note*:

You should never add the `CREATE' preface to the routine definition.

The properties `Name', `Schema' and `Server' in the `Properties' window
are read-only. Set or change the procedure name in the SQL editor.

To save changes you have made, use either `Save' or `Save All' buttons
of the Visual Studio main toolbar, or just press `Ctrl+S'. A
confirmation dialog will confirm whether you want the changes saved to
the database..


File: manual.info,  Node: connector-vstudio-using-triggers,  Next: connector-vstudio-using-udf,  Prev: connector-vstudio-using-storedroutines,  Up: connector-vstudio-using

20.3.3.10 Editing Triggers
..........................

To create a new trigger, right click on a node of a table for which you
wish to add a trigger. From the node's context menu, choose the `Create
Trigger' command. This command opens the SQL Editor.

To modify an existing trigger, double click on a node of the trigger
you wish to modify, or right click on this node and choose the `Alter
Trigger' command from a context menu. Either of the commands opens the
SQL Editor.

To create or alter the trigger definition using SQL Editor, type the
trigger statement in the SQL Editor using standard SQL.

*Note*:

You should enter only the trigger statement, that is the part of the
*Note `CREATE TRIGGER': create-trigger. query that is placed after the
`FOR EACH ROW' clause.

All other trigger properties are set in the `Properties' window. These
properties are:

   * `Definer'

   * `Event Manipulation'

   * `Name'

   * `Timing'

Some of these properties can have arbitrary text values, others accept
values only from a predefined set.

The properties `Event Table', `Schema' and `Server' in the `Properties'
window are read-only.

To save changes you have made, use either `Save' or `Save All' buttons
of the Visual Studio main toolbar, or just press `Ctrl+S'. A
confirmation dialog will confirm whether you want the changes saved to
the database.


File: manual.info,  Node: connector-vstudio-using-udf,  Next: connector-vstudio-using-dropping,  Prev: connector-vstudio-using-triggers,  Up: connector-vstudio-using

20.3.3.11 Editing User Defined Functions (UDF)
..............................................

To create a new User Defined Function (UDF), right click the UDFs node
under the connection node in Server Explorer. From the node's context
menu, choose the `Create UDF' command. This command opens the UDF
Editor.

To modify an existing UDF, double click on a node of the UDF you wish
to modify, or right click on this node and choose the Alter UDF command
from a context menu. Either of the commands opens the UDF Editor.

The UDF editor allows you to set the following properties through the
properties panel:

   * `Name'

   * `So-name (DLL name)'

   * `Return type'

   * `Is Aggregate'

The property Server in the `Properties' window is read-only.

To save changes you have made, use either `Save' or `Save All' buttons
of the Visual Studio main toolbar, or just press `Ctrl+S'. A
confirmation dialog will confirm whether you want the changes saved to
the database.


File: manual.info,  Node: connector-vstudio-using-dropping,  Next: connector-vstudio-using-cloning,  Prev: connector-vstudio-using-udf,  Up: connector-vstudio-using

20.3.3.12 Dropping database objects
...................................

Tables, views, stored routines, triggers, an UDFs can be dropped with
the appropriate `Drop' command from its context menu: `Drop Table',
`Drop View', `Drop Routine', `Drop Trigger', `Drop UDF'.

You will be asked to confirm the execution of the corresponding drop
query in a confirmation dialog.

Dropping of multiple objects is not supported.


File: manual.info,  Node: connector-vstudio-using-cloning,  Prev: connector-vstudio-using-dropping,  Up: connector-vstudio-using

20.3.3.13 Cloning database objects
..................................

Tables, views, stored procedures and functions can be cloned with the
appropriate `Clone' command from its context menu: `Clone Table', `Clone
View', `Clone Routine'. The clone commands open the corresponding
editor for a new object: the `Table Editor 'for cloning a table and the
SQL Editor for cloning a view or a routine.

To save the cloned object, use either `Save' or `Save All' buttons of
the Visual Studio main toolbar, or just press `Ctrl+S'. A confirmation
dialog will confirm whether you want the changes saved to the database.


File: manual.info,  Node: connector-vstudio-support,  Prev: connector-vstudio-using,  Up: connector-vstudio

20.3.4 Visual Studio Plugin Support
-----------------------------------

* Menu:

* connector-vstudio-faq::        Visual Studio Plugin FAQ

If you have a comment, or if you discover a bug, please, use our MySQL
bug tracking system (http://bugs.mysql.com (http://bugs.mysql.com)) to
report problem or add your suggestion.


File: manual.info,  Node: connector-vstudio-faq,  Prev: connector-vstudio-support,  Up: connector-vstudio-support

20.3.4.1 Visual Studio Plugin FAQ
.................................

*Questions*
   * 20.3.4.1.1: When creating a connection, typing the connection
     details causes the connection window to immediately close.

*Questions and Answers* *20.3.4.1.1: ** When creating a connection,
typing the connection details causes the connection window to
immediately close.  *

There are known issues with versions of Connector/NET earlier than
5.0.2. Connector/NET 1.0.x is known not to work. If you have any of
these versions installed, or have previously upgraded from an earlier
version, uninstall Connector/NET completely and then install
Connector/NET 5.0.2.


File: manual.info,  Node: connector-j,  Next: connector-mxj,  Prev: connector-vstudio,  Up: connectors-apis

20.4 MySQL Connector/J
======================

* Menu:

* connector-j-versions::         Connector/J Versions
* connector-j-installing::       Connector/J Installation
* connector-j-examples::         Connector/J Examples
* connector-j-reference::        Connector/J (JDBC) Reference
* connector-j-usagenotes::       Connector/J Notes and Tips
* connector-j-support::          Connector/J Support

MySQL provides connectivity for client applications developed in the
Java programming language via a JDBC driver, which is called MySQL
Connector/J.

MySQL Connector/J is a JDBC Type 4 driver. Different versions are
available that are compatible with the JDBC 3.0 and JDBC 4.0
specifications. The Type 4 designation means that the driver is
pure-Java implementation of the MySQL protocol and does not rely on the
MySQL client libraries.

Although JDBC is useful by itself, we would hope that if you are not
familiar with JDBC that after reading the first few sections of this
manual, that you would avoid using naked JDBC for all but the most
trivial problems and consider using one of the popular persistence
frameworks such as Hibernate (http://www.hibernate.org/), Spring's JDBC
templates (http://www.springframework.org/) or Ibatis SQL Maps
(http://ibatis.apache.org/) to do the majority of repetitive work and
heavier lifting that is sometimes required with JDBC.

This section is not designed to be a complete JDBC tutorial. If you
need more information about using JDBC you might be interested in the
following online tutorials that are more in-depth than the information
presented here:

   * JDBC Basics
     (http://java.sun.com/docs/books/tutorial/jdbc/basics/index.html)
     -- A tutorial from Sun covering beginner topics in JDBC

   * JDBC Short Course
     (http://java.sun.com/developer/onlineTraining/Database/JDBCShortCourse/index.html)
     -- A more in-depth tutorial from Sun and JGuru

*Key topics:*

   * For help with connection strings, connection options setting up
     your connection through JDBC, see *Note
     connector-j-reference-configuration-properties::.

   * For tips on using Connector/J and JDBC with generic J2EE toolkits,
     see *Note connector-j-usagenotes-j2ee::.

   * Developers using the Tomcat server platform, see *Note
     connector-j-usagenotes-tomcat::.

   * Developers using JBoss, see *Note connector-j-usagenotes-jboss::.

   * Developers using Spring, see *Note
     connector-j-usagenotes-spring-config::.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about using
JDBC with MySQL in the Knowledge Base articles about JDBC
(https://kb.mysql.com/search.php?cat=search&category=10). Access to the
MySQL Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: connector-j-versions,  Next: connector-j-installing,  Prev: connector-j,  Up: connector-j

20.4.1 Connector/J Versions
---------------------------

* Menu:

* connector-j-versions-java::    Java Versions Supported

There are currently four versions of MySQL Connector/J available:

   * Connector/J 5.1 is the Type 4 pure Java JDBC driver, which
     conforms to the JDBC 3.0 and JDBC 4.0 specifications. It provides
     compatibility with all the functionality of MySQL, including 4.1,
     5.0, 5.1 and the 6.0 alpha release featuring the new Falcon
     storage engine. Connector/J 5.1 provides ease of development
     features, including auto-registration with the Driver Manager,
     standardized validity checks, categorized SQLExceptions, support
     for the JDBC-4.0 XML processing, per connection client information,
     *Note `NCHAR': char, *Note `NVARCHAR': char. and `NCLOB' types.
     This release also includes all bug fixes up to and including
     Connector/J 5.0.6.

   * Connector/J 5.0 provides support for all the functionality offered
     by Connector/J 3.1 and includes distributed transaction (XA)
     support.

   * Connector/J 3.1 was designed for connectivity to MySQL 4.1 and
     MySQL 5.0 servers and provides support for all the functionality
     in MySQL 5.0 except distributed transaction (XA) support.

   * Connector/J 3.0 provides core functionality and was designed with
     connectivity to MySQL 3.x or MySQL 4.1 servers, although it will
     provide basic compatibility with later versions of MySQL.
     Connector/J 3.0 does not support server-side prepared statements,
     and does not support any of the features in versions of MySQL
     later than 4.1.

The following table summarizes the Connector/J versions available:

*Connector/J   *Driver Type*  *JDBC version* *MySQL Server  *Status*
version*                                     version*       
5.1            4              3.0, 4.0       4.1, 5.0,      Recommended
                                             5.1, 6.0       version
5.0            4              3.0            4.1, 5.0       Released
                                                            version
3.1            4              3.0            4.1, 5.0       Obsolete
3.0            4              3.0            3.x, 4.1       Obsolete

The current recommended version for Connector/J is 5.1. This guide
covers all four connector versions, with specific notes given where a
setting applies to a specific option.


File: manual.info,  Node: connector-j-versions-java,  Prev: connector-j-versions,  Up: connector-j-versions

20.4.1.1 Java Versions Supported
................................

The following table summarizes Connector/J Java dependencies:

*Connector/J version*  *Java RTE required*    *JDK required (to
                                              build source code)*
5.1                    1.4.x, 1.5.x, 1.6.x    1.6.x and 1.5.x (or
                                              older)
5.0                    1.3.x, 1.4.x, 1.5.x,   1.4.2, 1.5.x, 1.6.x
                       1.6.x                  
3.1                    1.2.x, 1.3.x, 1.4.x,   1.4.2, 1.5.x, 1.6.x
                       1.5.x, 1.6.x           
3.0                    1.2.x, 1.3.x, 1.4.x,   1.4.2, 1.5.x, 1.6.x
                       1.5.x, 1.6.x           

MySQL Connector/J does not support JDK-1.1.x or JDK-1.0.x.

Because of the implementation of java.sql.Savepoint, Connector/J 3.1.0
and newer will not run on a Java runtime older than 1.4 unless the
class verifier is turned off (by setting the `-Xverify:none' option to
the Java runtime). This is because the class verifier will try to load
the class definition for java.sql.Savepoint even though it is not
accessed by the driver unless you actually use savepoint functionality.

Caching functionality provided by Connector/J 3.1.0 or newer is also
not available on JVMs older than 1.4.x, as it relies on
java.util.LinkedHashMap which was first available in JDK-1.4.0.

If you are building Connector/J from source code using the source
distribution (see *Note connector-j-installing-source::) then you must
use JDK 1.4.2 or newer to compile the Connector package. For
Connector/J 5.1 you must have both JDK-1.6.x. and JDK-1.5.x installed
in order to be able to build the source code.


File: manual.info,  Node: connector-j-installing,  Next: connector-j-examples,  Prev: connector-j-versions,  Up: connector-j

20.4.2 Connector/J Installation
-------------------------------

* Menu:

* connector-j-installing-binary::  Installing Connector/J from a Binary Distribution
* connector-j-installing-classpath::  Installing the Driver and Configuring the `CLASSPATH'
* connector-j-installing-upgrading::  Upgrading from an Older Version
* connector-j-installing-source::  Installing from the Development Source Tree

You can install the Connector/J package using either the binary or
source distribution. The binary distribution provides the easiest
method for installation; the source distribution enables you to
customize your installation further. With either solution, you must
manually add the Connector/J location to your Java `CLASSPATH'.

If you are upgrading from a previous version, read the upgrade
information before continuing. See *Note
connector-j-installing-upgrading::.


File: manual.info,  Node: connector-j-installing-binary,  Next: connector-j-installing-classpath,  Prev: connector-j-installing,  Up: connector-j-installing

20.4.2.1 Installing Connector/J from a Binary Distribution
..........................................................

The easiest method of installation is to use the binary distribution of
the Connector/J package. The binary distribution is available either as
a Tar/Gzip or Zip file which you must extract to a suitable location
and then optionally make the information about the package available by
changing your `CLASSPATH' (see *Note
connector-j-installing-classpath::).

MySQL Connector/J is distributed as a .zip or .tar.gz archive
containing the sources, the class files, and the JAR archive named
`mysql-connector-java-[VERSION]-bin.jar', and starting with Connector/J
3.1.8 a debug build of the driver in a file named
`mysql-connector-java-[VERSION]-bin-g.jar'.

Starting with Connector/J 3.1.9, the `.class' files that constitute the
JAR files are only included as part of the driver JAR file.

You should not use the debug build of the driver unless instructed to
do so when reporting a problem or a bug to MySQL AB, as it is not
designed to be run in production environments, and will have adverse
performance impact when used. The debug binary also depends on the
Aspect/J runtime library, which is located in the
`src/lib/aspectjrt.jar' file that comes with the Connector/J
distribution.

You will need to use the appropriate graphical or command-line utility
to extract the distribution (for example, WinZip for the .zip archive,
and `tar' for the .tar.gz archive). Because there are potentially long
file names in the distribution, we use the GNU tar archive format. You
will need to use GNU tar (or an application that understands the GNU tar
archive format) to unpack the .tar.gz variant of the distribution.


File: manual.info,  Node: connector-j-installing-classpath,  Next: connector-j-installing-upgrading,  Prev: connector-j-installing-binary,  Up: connector-j-installing

20.4.2.2 Installing the Driver and Configuring the `CLASSPATH'
..............................................................

Once you have extracted the distribution archive, you can install the
driver by placing `mysql-connector-java-[version]-bin.jar 'in your
classpath, either by adding the full path to it to your `CLASSPATH'
environment variable, or by directly specifying it with the command
line switch -cp when starting your JVM.

If you are going to use the driver with the JDBC DriverManager, you
would use `com.mysql.jdbc.Driver' as the class that implements
java.sql.Driver.

You can set the `CLASSPATH' environment variable under UNIX, Linux or
Mac OS X either locally for a user within their `.profile', `.login' or
other login file. You can also set it globally by editing the global
`/etc/profile' file.

For example, under a C shell (csh, tcsh) you would add the Connector/J
driver to your `CLASSPATH' using the following:

     shell> setenv CLASSPATH /path/mysql-connector-java-[ver]-bin.jar:$CLASSPATH

Or with a Bourne-compatible shell (sh, ksh, bash):

     shell> export set CLASSPATH=/path/mysql-connector-java-[ver]-bin.jar:$CLASSPATH

Within Windows 2000, Windows XP, Windows Server 2003 and Windows Vista,
you must set the environment variable through the System Control Panel.

If you want to use MySQL Connector/J with an application server such as
GlassFish, Tomcat or JBoss, you will have to read your vendor's
documentation for more information on how to configure third-party
class libraries, as most application servers ignore the `CLASSPATH'
environment variable. For configuration examples for some J2EE
application servers, see *Note connector-j-usagenotes-j2ee::. However,
the authoritative source for JDBC connection pool configuration
information for your particular application server is the documentation
for that application server.

If you are developing servlets or JSPs, and your application server is
J2EE-compliant, you can put the driver's .jar file in the WEB-INF/lib
subdirectory of your webapp, as this is a standard location for third
party class libraries in J2EE web applications.

You can also use the MysqlDataSource or MysqlConnectionPoolDataSource
classes in the `com.mysql.jdbc.jdbc2.optional' package, if your J2EE
application server supports or requires them. Starting with Connector/J
5.0.0, the `javax.sql.XADataSource' interface is implemented via the
`com.mysql.jdbc.jdbc2.optional.MysqlXADataSource' class, which supports
XA distributed transactions when used in combination with MySQL server
version 5.0.

The various MysqlDataSource classes support the following parameters
(through standard set mutators):

   * user

   * password

   * serverName (see the previous section about fail-over hosts)

   * databaseName

   * port


File: manual.info,  Node: connector-j-installing-upgrading,  Next: connector-j-installing-source,  Prev: connector-j-installing-classpath,  Up: connector-j-installing

20.4.2.3 Upgrading from an Older Version
........................................

* Menu:

* connector-j-installing-upgrading-3-0-to-3-1::  Upgrading from MySQL Connector/J 3.0 to 3.1
* connector-j-installing-upgrading-5-1::  Upgrading to MySQL Connector/J 5.1.x
* connector-j-installing-upgrading-issues::  JDBC-Specific Issues When Upgrading to MySQL Server 4.1 or Newer

We try to keep the upgrade process as easy as possible, however as is
the case with any software, sometimes changes need to be made in new
versions to support new features, improve existing functionality, or
comply with new standards.

This section has information about what users who are upgrading from
one version of Connector/J to another (or to a new version of the MySQL
server, with respect to JDBC functionality) should be aware of.


File: manual.info,  Node: connector-j-installing-upgrading-3-0-to-3-1,  Next: connector-j-installing-upgrading-5-1,  Prev: connector-j-installing-upgrading,  Up: connector-j-installing-upgrading

20.4.2.4 Upgrading from MySQL Connector/J 3.0 to 3.1
....................................................

Connector/J 3.1 is designed to be backward-compatible with Connector/J
3.0 as much as possible. Major changes are isolated to new
functionality exposed in MySQL-4.1 and newer, which includes Unicode
character sets, server-side prepared statements, SQLState codes
returned in error messages by the server and various performance
enhancements that can be enabled or disabled via configuration
properties.

   * *Unicode Character Sets* -- See the next section, as well as *Note
     charset::, for information on this new feature of MySQL. If you
     have something misconfigured, it will usually show up as an error
     with a message similar to `Illegal mix of collations'.

   * *Server-side Prepared Statements* -- Connector/J 3.1 will
     automatically detect and use server-side prepared statements when
     they are available (MySQL server version 4.1.0 and newer).

     Starting with version 3.1.7, the driver scans SQL you are
     preparing via all variants of `Connection.prepareStatement()' to
     determine if it is a supported type of statement to prepare on the
     server side, and if it is not supported by the server, it instead
     prepares it as a client-side emulated prepared statement. You can
     disable this feature by passing emulateUnsupportedPstmts=false in
     your JDBC URL.

     If your application encounters issues with server-side prepared
     statements, you can revert to the older client-side emulated
     prepared statement code that is still presently used for MySQL
     servers older than 4.1.0 with the connection property
     useServerPrepStmts=false

   * *Datetimes* with all-zero components (`0000-00-00 ...') -- These
     values can not be represented reliably in Java.  Connector/J 3.0.x
     always converted them to NULL when being read from a ResultSet.

     Connector/J 3.1 throws an exception by default when these values
     are encountered as this is the most correct behavior according to
     the JDBC and SQL standards. This behavior can be modified using the
     zeroDateTimeBehavior configuration property. The allowable values
     are:

        * `exception' (the default), which throws an SQLException with
          an SQLState of `S1009'.

        * `convertToNull', which returns `NULL' instead of the date.

        * `round', which rounds the date to the nearest closest value
          which is `0001-01-01'.

     Starting with Connector/J 3.1.7, `ResultSet.getString()' can be
     decoupled from this behavior via noDatetimeStringSync=true (the
     default value is `false') so that you can retrieve the unaltered
     all-zero value as a String. It should be noted that this also
     precludes using any time zone conversions, therefore the driver
     will not allow you to enable noDatetimeStringSync and useTimezone
     at the same time.

   * *New SQLState Codes* -- Connector/J 3.1 uses SQL:1999 SQLState
     codes returned by the MySQL server (if supported), which are
     different from the legacy X/Open state codes that Connector/J 3.0
     uses. If connected to a MySQL server older than MySQL-4.1.0 (the
     oldest version to return SQLStates as part of the error code), the
     driver will use a built-in mapping. You can revert to the old
     mapping by using the configuration property useSqlStateCodes=false.

   * *`ResultSet.getString()'* -- Calling `ResultSet.getString()' on a
     *Note `BLOB': blob. column will now return the address of the
     `byte[]' array that represents it, instead of a `String'
     representation of the *Note `BLOB': blob.  *Note `BLOB': blob.
     values have no character set, so they cannot be converted to
     `java.lang.String's without data loss or corruption.

     To store strings in MySQL with LOB behavior, use one of the *Note
     `TEXT': blob. types, which the driver will treat as a
     `java.sql.Clob'.

   * *Debug builds* -- Starting with Connector/J 3.1.8 a debug build of
     the driver in a file named
     `mysql-connector-java-[VERSION]-bin-g.jar' is shipped alongside
     the normal binary jar file that is named
     `mysql-connector-java-[VERSION]-bin.jar'.

     Starting with Connector/J 3.1.9, we do not ship the .class files
     unbundled, they are only available in the JAR archives that ship
     with the driver.

     You should not use the debug build of the driver unless instructed
     to do so when reporting a problem or bug, as it is not designed to
     be run in production environments, and will have adverse
     performance impact when used. The debug binary also depends on the
     Aspect/J runtime library, which is located in the
     `src/lib/aspectjrt.jar' file that comes with the Connector/J
     distribution.


File: manual.info,  Node: connector-j-installing-upgrading-5-1,  Next: connector-j-installing-upgrading-issues,  Prev: connector-j-installing-upgrading-3-0-to-3-1,  Up: connector-j-installing-upgrading

20.4.2.5 Upgrading to MySQL Connector/J 5.1.x
.............................................

   * In Connector/J 5.0.x and earlier, the alias for a table in a *Note
     `SELECT': select. statement is returned when accessing the result
     set metadata using `ResultSetMetaData.getColumnName()'.  This
     behavior however is not JDBC compliant, and in Connector/J 5.1
     this behavior was changed so that the original table name, rather
     than the alias, is returned.

     The JDBC-compliant behavior is designed to let API users
     reconstruct the DML statement based on the metadata within
     `ResultSet' and `ResultSetMetaData'.

     You can get the alias for a column in a result set by calling
     `ResultSetMetaData.getColumnLabel()'.  If you want to use the old
     non-compliant behavior with `ResultSetMetaData.getColumnName()',
     use the `useOldAliasMetadataBehavior' option and set the value to
     `true'.

     In Connector/J 5.0.x the default value of
     `useOldAliasMetadataBehavior' was true, but in Connector/J 5.1
     this was changed to a default value of false.


File: manual.info,  Node: connector-j-installing-upgrading-issues,  Prev: connector-j-installing-upgrading-5-1,  Up: connector-j-installing-upgrading

20.4.2.6 JDBC-Specific Issues When Upgrading to MySQL Server 4.1 or Newer
.........................................................................

   * _Using the UTF-8 Character Encoding_ - Prior to MySQL server
     version 4.1, the UTF-8 character encoding was not supported by the
     server, however the JDBC driver could use it, allowing storage of
     multiple character sets in latin1 tables on the server.

     Starting with MySQL-4.1, this functionality is deprecated.  If you
     have applications that rely on this functionality, and can not
     upgrade them to use the official Unicode character support in
     MySQL server version 4.1 or newer, you should add the following
     property to your connection URL:

     useOldUTF8Behavior=true

   * _Server-side Prepared Statements_ - Connector/J 3.1 will
     automatically detect and use server-side prepared statements when
     they are available (MySQL server version 4.1.0 and newer). If your
     application encounters issues with server-side prepared
     statements, you can revert to the older client-side emulated
     prepared statement code that is still presently used for MySQL
     servers older than 4.1.0 with the following connection property:

     useServerPrepStmts=false


File: manual.info,  Node: connector-j-installing-source,  Prev: connector-j-installing-upgrading,  Up: connector-j-installing

20.4.2.7 Installing from the Development Source Tree
....................................................

*Caution*:

You should read this section only if you are interested in helping us
test our new code. If you just want to get MySQL Connector/J up and
running on your system, you should use a standard binary release
distribution.

To install MySQL Connector/J from the development source tree, make
sure that you have the following prerequisites:

   * A Bazaar client, to check out the sources from our Launchpad
     repository (available from `http://bazaar-vcs.org/').

   * Apache Ant version 1.7 or newer (available from
     `http://ant.apache.org/').

   * JDK 1.4.2 or later. Although MySQL Connector/J can be be used with
     older JDKs, to compile it from source you must have at least JDK
     1.4.2. If you are building Connector/J 5.1 you will need JDK 1.6.x
     and an older JDK such as JDK 1.5.x.  You will then need to point
     your JAVA_HOME environment variable at the older installation.

The source code repository for MySQL Connector/J is located on
Launchpad at `https://code.launchpad.net/connectorj'.

To check out and compile a specific branch of MySQL Connector/J, follow
these steps:

  1. Check out the latest code from the branch that you want with one
     of the following commands.

     To check out the latest development branch use:

          shell> bzr branch lp:connectorj

     This creates a `connectorj' subdirectory in the current directory
     that contains the latest sources for the requested branch.

     To check out the latest 5.1 code use:

          shell> bzr branch lp:connectorj/5.1

     This will create a `5.1' subdirectory in the current directory
     containing the latest 5.1 code.

  2. If you are building Connector/J 5.1 make sure that you have both
     JDK 1.6.x installed and an older JDK such as JDK 1.5.x.  This is
     because Connector/J supports both JDBC 3.0 (which was prior to JDK
     1.6.x) and JDBC 4.0. Set your JAVA_HOME environment variable to
     the path of the older JDK installation.

  3. Change location to either the `connectorj' or `5.1' directory,
     depending on which branch you want to build, to make it your
     current working directory. For example:

          shell> cd connectorj

  4. If you are building Connector/J 5.1 you need to edit the
     `build.xml' to reflect the location of your JDK 1.6.x
     installation. The lines that you need to change are:

                      <property name="com.mysql.jdbc.java6.javac" value="C:\jvms\jdk1.6.0\bin\javac.exe" />
                      <property name="com.mysql.jdbc.java6.rtjar" value="C:\jvms\jdk1.6.0\jre\lib\rt.jar" />

     Alternatively, you can set the value of these property names
     through the Ant `-D' option.

  5. Issue the following command to compile the driver and create a
     `.jar' file suitable for installation:

          shell> ant dist

     This creates a `build' directory in the current directory, where
     all build output will go. A directory is created in the `build'
     directory that includes the version number of the sources you are
     building from. This directory contains the sources, compiled
     `.class' files, and a `.jar' file suitable for deployment. For
     other possible targets, including ones that will create a fully
     packaged distribution, issue the following command:

          shell> ant -projecthelp

  6. A newly created `.jar' file containing the JDBC driver will be
     placed in the directory `build/mysql-connector-java-[VERSION]'.

     Install the newly created JDBC driver as you would a binary `.jar'
     file that you download from MySQL by following the instructions in
     *Note connector-j-installing-classpath::.

A package containing both the binary and source code for Connector/J
5.1 can also be found at the following location: Connector/J 5.1
Download (http://dev.mysql.com/downloads/connector/j/5.1.html)


File: manual.info,  Node: connector-j-examples,  Next: connector-j-reference,  Prev: connector-j-installing,  Up: connector-j

20.4.3 Connector/J Examples
---------------------------

Examples of using Connector/J are located throughout this document,
this section provides a summary and links to these examples.

   * *Note connector-j-examples-connection-drivermanager::

   * *Note connector-j-examples-execute-select::

   * *Note connector-j-examples-stored-procedure::

   * *Note connector-j-examples-preparecall::

   * *Note connector-j-examples-output-param::

   * *Note connector-j-examples-callablestatement::

   * *Note connector-j-examples-retrieving-results-params::

   * *Note connector-j-examples-autoincrement-getgeneratedkeys::

   * *Note connector-j-examples-autoincrement-select::

   * *Note connector-j-examples-autoincrement-updateable-resultsets::

   * *Note connector-j-examples-connectionpool-j2ee::

   * *Note connector-j-examples-transaction-retry::


File: manual.info,  Node: connector-j-reference,  Next: connector-j-usagenotes,  Prev: connector-j-examples,  Up: connector-j

20.4.4 Connector/J (JDBC) Reference
-----------------------------------

* Menu:

* connector-j-reference-configuration-properties::  Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J
* connector-j-reference-implementation-notes::  JDBC API Implementation Notes
* connector-j-reference-type-conversions::  Java, JDBC and MySQL Types
* connector-j-reference-charsets::  Using Character Sets and Unicode
* connector-j-reference-using-ssl::  Connecting Securely Using SSL
* connector-j-reference-replication-connection::  Using Master/Slave Replication with ReplicationConnection
* connector-j-reference-error-sqlstates::  Mapping MySQL Error Numbers to SQLStates

This section of the manual contains reference material for MySQL
Connector/J, some of which is automatically generated during the
Connector/J build process.


File: manual.info,  Node: connector-j-reference-configuration-properties,  Next: connector-j-reference-implementation-notes,  Prev: connector-j-reference,  Up: connector-j-reference

20.4.4.1 Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J
...............................................................................................

The name of the class that implements java.sql.Driver in MySQL
Connector/J is `com.mysql.jdbc.Driver'. The `org.gjt.mm.mysql.Driver'
class name is also usable to remain backward-compatible with MM.MySQL.
You should use this class name when registering the driver, or when
otherwise configuring software to use MySQL Connector/J.

The JDBC URL format for MySQL Connector/J is as follows, with items in
square brackets ([, ]) being optional:

     jdbc:mysql://[host][,failoverhost...][:port]/[database] »
     [?propertyName1][=propertyValue1][&propertyName2][=propertyValue2]...

If the host name is not specified, it defaults to 127.0.0.1. If the
port is not specified, it defaults to 3306, the default port number for
MySQL servers.

     jdbc:mysql://[host:port],[host:port].../[database] »
     [?propertyName1][=propertyValue1][&propertyName2][=propertyValue2]...

If the database is not specified, the connection will be made with no
default database. In this case, you will need to either call the
`setCatalog()' method on the Connection instance or fully-specify table
names using the database name (i.e. `SELECT dbname.tablename.colname
FROM dbname.tablename...') in your SQL. Not specifying the database to
use upon connection is generally only useful when building tools that
work with multiple databases, such as GUI database managers.

MySQL Connector/J has fail-over support. This allows the driver to
fail-over to any number of slave hosts and still perform read-only
queries. Fail-over only happens when the connection is in an
`autoCommit(true)' state, because fail-over can not happen reliably
when a transaction is in progress. Most application servers and
connection pools set `autoCommit' to `true' at the end of every
transaction/connection use.

The fail-over functionality has the following behavior:

   * If the URL property autoReconnect is false: Failover only happens
     at connection initialization, and failback occurs when the driver
     determines that the first host has become available again.

   * If the URL property autoReconnect is true: Failover happens when
     the driver determines that the connection has failed (before
     _every_ query), and falls back to the first host when it determines
     that the host has become available again (after
     `queriesBeforeRetryMaster' queries have been issued).

In either case, whenever you are connected to a "failed-over" server,
the connection will be set to read-only state, so queries that would
modify data will have exceptions thrown (the query will *never* be
processed by the MySQL server).

Configuration properties define how Connector/J will make a connection
to a MySQL server. Unless otherwise noted, properties can be set for a
DataSource object or for a Connection object.

Configuration Properties can be set in one of the following ways:

   * Using the set*() methods on MySQL implementations of
     java.sql.DataSource (which is the preferred method when using
     implementations of java.sql.DataSource):

        * com.mysql.jdbc.jdbc2.optional.MysqlDataSource

        * com.mysql.jdbc.jdbc2.optional.MysqlConnectionPoolDataSource

   * As a key/value pair in the java.util.Properties instance passed to
     `DriverManager.getConnection()' or `Driver.connect()'

   * As a JDBC URL parameter in the URL given to
     `java.sql.DriverManager.getConnection()',
     `java.sql.Driver.connect()' or the MySQL implementations of the
     `javax.sql.DataSource' `setURL()' method.

     *Note*:

     If the mechanism you use to configure a JDBC URL is XML-based, you
     will need to use the XML character literal &amp; to separate
     configuration parameters, as the ampersand is a reserved character
     for XML.

The properties are listed in the following tables.

Connection/Authentication

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
user                   The user to connect as                       all
                                                                    versions
password               The password to use when connecting          all
                                                                    versions
socketFactory          The name of the class that the       com.mysql.jdbc.StandardSocketFactory3.0.3
                       driver should use for creating               
                       socket connections to the server.            
                       This class must implement the                
                       interface                                    
                       'com.mysql.jdbc.SocketFactory' and           
                       have public no-args constructor.             
connectTimeout         Timeout for socket connect (in       0       3.0.1
                       milliseconds), with 0 being no               
                       timeout.  Only works on JDK-1.4 or           
                       newer. Defaults to '0'.                      
socketTimeout          Timeout on network socket            0       3.0.1
                       operations (0, the default means no          
                       timeout).                                    
connectionLifecycleInterceptorsA comma-delimited list of classes            5.1.4
                       that implement                               
                       "com.mysql.jdbc.ConnectionLifecycleInterceptor"        
                       that should notified of connection           
                       lifecycle events (creation,                  
                       destruction, commit, rollback,               
                       setCatalog and setAutoCommit) and            
                       potentially alter the execution of           
                       these commands.                              
                       ConnectionLifecycleInterceptors are          
                       "stackable", more than one                   
                       interceptor may be specified via             
                       the configuration property as a              
                       comma-delimited list, with the               
                       interceptors executed in order from          
                       left to right.                               
useConfigs             Load the comma-delimited list of             3.1.5
                       configuration properties before              
                       parsing the URL or applying                  
                       user-specified properties. These             
                       configurations are explained in the          
                       'Configurations' of the                      
                       documentation.                               
interactiveClient      Set the CLIENT_INTERACTIVE flag,     false   3.1.0
                       which tells MySQL to timeout                 
                       connections based on                         
                       INTERACTIVE_TIMEOUT instead of               
                       WAIT_TIMEOUT                                 
localSocketAddress     Host name or IP address given to             5.0.5
                       explicitly configure the interface           
                       that the driver will bind the                
                       client side of the TCP/IP                    
                       connection to when connecting.               
mysqlIOFactory         The name of the class which          com.mysql.jdbc.MysqlIOprotocol6.0.0
                       implements "com.mysql.jdbc.MysqlIO"          
                       for communicating with mysqld.               
                       (default is                                  
                       "com.mysql.jdbc.MysqlIOprotocol")            
propertiesTransform    An implementation of                         3.1.4
                       com.mysql.jdbc.ConnectionPropertiesTransform        
                       that the driver will use to modify           
                       URL properties passed to the driver          
                       before attempting a connection               
useCompression         Use zlib compression when            false   3.0.17
                       communicating with the server                
                       (true/false)?  Defaults to 'false'.          

Networking

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
tcpKeepAlive           If connecting using TCP/IP, should   true    5.0.7
                       the driver set SO_KEEPALIVE?                 
tcpNoDelay             If connecting using TCP/IP, should   true    5.0.7
                       the driver set SO_TCP_NODELAY                
                       (disabling the Nagle Algorithm)?             
tcpRcvBuf              If connecting using TCP/IP, should   0       5.0.7
                       the driver set SO_RCV_BUF to the             
                       given value? The default value of            
                       '0', means use the platform default          
                       value for this property)                     
tcpSndBuf              If connecting using TCP/IP, shuold   0       5.0.7
                       the driver set SO_SND_BUF to the             
                       given value? The default value of            
                       '0', means use the platform default          
                       value for this property)                     
tcpTrafficClass        If connecting using TCP/IP, should   0       5.0.7
                       the driver set traffic class or              
                       type-of-service fields ?See the              
                       documentation for                            
                       java.net.Socket.setTrafficClass()            
                       for more information.                        

High Availability and Clustering

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
autoReconnect          Should the driver try to             false   1.1
                       re-establish stale and/or dead               
                       connections? If enabled the driver           
                       will throw an exception for a                
                       queries issued on a stale or dead            
                       connection, which belong to the              
                       current transaction, but will                
                       attempt reconnect before the next            
                       query issued on the connection in a          
                       new transaction. The use of this             
                       feature is not recommended, because          
                       it has side effects related to               
                       session state and data consistency           
                       when applications do not handle              
                       SQLExceptions properly, and is only          
                       designed to be used when you are             
                       unable to configure your                     
                       application to handle SQLExceptions          
                       resulting from dead and stale                
                       connections properly.                        
                       Alternatively, investigate setting           
                       the MySQL server variable                    
                       "wait_timeout" to some high value            
                       rather than the default of 8 hours.          
autoReconnectForPools  Use a reconnection strategy          false   3.1.3
                       appropriate for connection pools             
                       (defaults to 'false')                        
failOverReadOnly       When failing over in autoReconnect   true    3.0.12
                       mode, should the connection be set           
                       to 'read-only'?                              
maxReconnects          Maximum number of reconnects to      3       1.1
                       attempt if autoReconnect is true,            
                       default is '3'.                              
reconnectAtTxEnd       If autoReconnect is set to true,     false   3.0.10
                       should the driver attempt                    
                       reconnections at the end of every            
                       transaction?                                 
initialTimeout         If autoReconnect is enabled, the     2       1.1
                       initial time to wait between                 
                       re-connect attempts (in seconds,             
                       defaults to '2').                            
roundRobinLoadBalance  When autoReconnect is enabled, and   false   3.1.2
                       failoverReadonly is false, should we         
                       pick hosts to connect to on a                
                       round-robin basis?                           
queriesBeforeRetryMasterNumber of queries to issue before    50      3.0.2
                       falling back to master when failed           
                       over (when using multi-host                  
                       failover). Whichever condition is            
                       met first,                                   
                       'queriesBeforeRetryMaster' or                
                       'secondsBeforeRetryMaster' will              
                       cause an attempt to be made to               
                       reconnect to the master. Defaults            
                       to 50.                                       
secondsBeforeRetryMasterHow long should the driver wait,     30      3.0.2
                       when failed over, before attempting          
selfDestructOnPingMaxOperations=If set to a non-zero value, the     0       5.1.6
                       driver will report close the                 
                       connection and report failure when           
                       Connection.ping() or                         
                       Connection.isValid(int) is called            
                       if the connnection's count of                
                       commands sent to the server exceeds          
                       this value.                                  
selfDestructOnPingSecondsLifetimeIf set to a non-zero value, the      0       5.1.6
                       driver will report close the                 
                       connection and report failure when           
                       Connection.ping() or                         
                       Connection.isValid(int) is called            
                       if the connnection's lifetime                
                       exceeds this value.                          
resourceId             A globally unique name that                  5.0.1
                       identifies the resource that this            
                       datasource or connection is                  
                       connected to, used for                       
                       XAResource.isSameRM() when the               
                       driver cannot determine this value           
                       based on host names used in the URL          

Security

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
allowMultiQueries      Allow the use of ';' to delimit      false   3.1.1
                       multiple queries during one                  
                       statement (true/false), defaults to          
                       'false'                                      
useSSL                 Use SSL when communicating with the  false   3.0.2
                       server (true/false), defaults to             
                       'false'                                      
requireSSL             Require SSL connection if            false   3.1.0
                       useSSL=true? (defaults to 'false').          
verifyServerCertificateIf "useSSL" is set to "true",        true    5.1.6
                       should the driver verify the                 
                       server's certificate? When using             
                       this feature, the keystore                   
                       parameters should be specified by            
                       the "clientCertificateKeyStore*"             
                       properties, rather than system               
                       properties.                                  
clientCertificateKeyStoreUrlURL to the client certificate                5.1.0
                       KeyStore (if not specified, use              
                       defaults)                                    
clientCertificateKeyStoreTypeKeyStore type for client                     5.1.0
                       certificates (NULL or empty means            
                       use default, standard keystore               
                       types supported by the JVM are "JKS"         
                       and "PKCS12", your environment may           
                       have more available depending on             
                       what security products are                   
                       installed and available to the JVM.          
clientCertificateKeyStorePasswordPassword for the client                      5.1.0
                       certificates KeyStore                        
trustCertificateKeyStoreUrlURL to the trusted root certificate          5.1.0
                       KeyStore (if not specified, use              
                       defaults)                                    
trustCertificateKeyStoreTypeKeyStore type for trusted root               5.1.0
                       certificates (NULL or empty means            
                       use default, standard keystore               
                       types supported by the JVM are               
                       "JKS" and "PKCS12", your                     
                       environment may have more available          
                       depending on what security products          
                       are installed and available to the           
                       JVM.                                         
trustCertificateKeyStorePasswordPassword for the trusted root                5.1.0
                       certificates KeyStore                        
allowLoadLocalInfile   Should the driver allow use of       true    3.0.3
                       'LOAD DATA LOCAL INFILE...'                  
                       (defaults to 'true').                        
allowUrlInLocalInfile  Should the driver allow URLs in      false   3.1.4
                       'LOAD DATA LOCAL INFILE' statements?         
paranoid               Take measures to prevent exposure    false   3.0.1
                       sensitive information in error               
                       messages and clear data structures           
                       holding sensitive data when                  
                       possible? (defaults to 'false')              

Performance Extensions

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
callableStmtCacheSize  If 'cacheCallableStmts' is enabled,  100     3.1.2
                       how many callable statements should          
                       be cached?                                   
metadataCacheSize      The number of queries to cache       50      3.1.1
                       ResultSetMetadata for if                     
                       cacheResultSetMetaData is set to             
                       'true' (default 50)                          
prepStmtCacheSize      If prepared statement caching is     25      3.0.10
                       enabled, how many prepared                   
                       statements should be cached?                 
prepStmtCacheSqlLimit  If prepared statement caching is     256     3.0.10
                       enabled, what is the largest SQL the         
                       driver will cache the parsing for?           
alwaysSendSetIsolation Should the driver always             true    3.1.7
                       communicate with the database when           
                       Connection.setTransactionIsolation()         
                       is called? If set to false, the              
                       driver will only communicate with            
                       the database when the requested              
                       transaction isolation is different           
                       than the whichever is newer, the             
                       last value that was set via                  
                       Connection.setTransactionIsolation(),        
                       or the value that was read from the          
                       server when the connection was               
                       established.                                 
maintainTimeStats      Should the driver maintain various   true    3.1.9
                       internal timers to enable idle time          
                       calculations as well as more                 
                       verbose error messages when the              
                       connection to the server fails?              
                       Setting this property to false               
                       removes at least two calls to                
                       System.getCurrentTimeMillis() per            
                       query.                                       
useCursorFetch         If connected to MySQL > 5.0.2, and   false   5.0.0
                       setFetchSize() > 0 on a statement,           
                       should that statement use                    
                       cursor-based fetching to retrieve            
                       rows?                                        
blobSendChunkSize      Chunk to use when sending            1048576 3.1.9
                       BLOB/CLOBs via                               
                       ServerPreparedStatements                     
cacheCallableStmts     Should the driver cache the parsing  false   3.1.2
                       stage of CallableStatements                  
cachePrepStmts         Should the driver cache the parsing  false   3.0.10
                       stage of PreparedStatements of               
                       client-side prepared statements,             
                       the "check" for suitability of               
                       server-side prepared and server-side         
                       prepared statements themselves?              
cacheResultSetMetadata Should the driver cache              false   3.1.1
                       ResultSetMetaData for Statements and         
                       PreparedStatements? (Req. JDK-1.4+,          
                       true/false, default 'false')                 
cacheServerConfigurationShould the driver cache the results  false   3.1.5
                       of 'SHOW VARIABLES' and 'SHOW                
                       COLLATION' on a per-URL basis?               
defaultFetchSize       The driver will call                 0       3.1.9
                       setFetchSize(n) with this value on           
                       all newly-created Statements                 
dontTrackOpenResources The JDBC specification requires the  false   3.1.7
                       driver to automatically track and            
                       close resources, however if your             
                       application doesn't do a good job            
                       of explicitly calling close() on             
                       statements or result sets, this can          
                       cause memory leakage. Setting this           
                       property to true relaxes this                
                       constraint, and can be more memory           
                       efficient for some applications.             
dynamicCalendars       Should the driver retrieve the       false   3.1.5
                       default calendar when required, or           
                       cache it per connection/session?             
elideSetAutoCommits    If using MySQL-4.1 or newer, should  false   3.1.3
                       the driver only issue 'set                   
                       autocommit=n' queries when the               
                       server's state doesn't match the             
                       requested state by                           
                       Connection.setAutoCommit(boolean)?           
enableQueryTimeouts    When enabled, query timeouts set     true    5.0.6
                       via Statement.setQueryTimeout() use          
                       a shared java.util.Timer instance            
                       for scheduling. Even if the timeout          
                       doesn't expire before the query is           
                       processed, there will be memory              
                       used by the TimerTask for the given          
                       timeout which will not be reclaimed          
                       until the time the timeout would             
                       have expired if it hadn't been               
                       cancelled by the driver. High-load           
                       environments might want to consider          
                       disabling this functionality.                
holdResultsOpenOverStatementCloseShould the driver close result sets  false   3.1.7
                       on Statement.close() as required by          
                       the JDBC specification?                      
largeRowSizeThreshold  What size result set row should the  2048    5.1.1
                       JDBC driver consider "large", and            
                       thus use a more memory-efficient             
                       way of representing the row                  
                       internally?                                  
loadBalanceStrategy    If using a load-balanced connection  random  5.0.6
                       to connect to SQL nodes in a MySQL           
                       Cluster/NDB configuration (by using          
                       the URL prefix                               
                       "jdbc:mysql:loadbalance://"), which          
                       load balancing algorithm should the          
                       driver use: (1) "random" - the               
                       driver will pick a random host for           
                       each request. This tends to work             
                       better than round-robin, as the              
                       randomness will somewhat account             
                       for spreading loads where requests           
                       vary in response time, while                 
                       round-robin can sometimes lead to            
                       overloaded nodes if there are                
                       variations in response times across          
                       the workload. (2)                            
                       "bestResponseTime" - the driver              
                       will route the request to the host           
                       that had the best response time for          
                       the previous transaction.                    
locatorFetchBufferSize If 'emulateLocators' is configured   1048576 3.2.1
                       to 'true', what size buffer should           
                       be used when fetching BLOB data for          
                       getBinaryInputStream?                        
rewriteBatchedStatementsShould the driver use multiqueries   false   3.1.13
                       (irregardless of the setting of              
                       "allowMultiQueries") as well as              
                       rewriting of prepared statements             
                       for INSERT into multi-value inserts          
                       when executeBatch() is called?               
                       Notice that this has the potential           
                       for SQL injection if using plain             
                       java.sql.Statements and your code            
                       doesn't sanitize input correctly.            
                       Notice that for prepared statements,         
                       server-side prepared statements can          
                       not currently take advantage of              
                       this rewrite option, and that if             
                       you do not specify stream lengths            
                       when using                                   
                       PreparedStatement.set*Stream(), the          
                       driver will not be able to                   
                       determine the optimum number of              
                       parameters per batch and you might           
                       receive an error from the driver             
                       that the resultant packet is too             
                       large.                                       
                       Statement.getGeneratedKeys() for             
                       these rewritten statements only              
                       works when the entire batch includes         
                       INSERT statements.                           
useDirectRowUnpack     Use newer result set row unpacking   true    5.1.1
                       code that skips a copy from network          
                       buffers to a MySQL packet instance           
                       and instead reads directly into the          
                       result set row data buffers.                 
useDynamicCharsetInfo  Should the driver use a              true    5.0.6
                       per-connection cache of character            
                       set information queried from the             
                       server when necessary, or use a              
                       built-in static mapping that is              
                       more efficient, but isn't aware of           
                       custom character sets or character           
                       sets implemented after the release           
                       of the JDBC driver?                          
useFastDateParsing     Use internal                         true    5.0.5
                       String->Date/Time/Timestamp                  
                       conversion routines to avoid                 
                       excessive object creation?                   
useFastIntParsing      Use internal String->Integer         true    3.1.4
                       conversion routines to avoid                 
                       excessive object creation?                   
useJvmCharsetConvertersAlways use the character encoding    false   5.0.1
                       routines built into the JVM, rather          
                       than using lookup tables for                 
                       single-byte character sets?                  
useLocalSessionState   Should the driver refer to the       false   3.1.7
                       internal values of autocommit and            
                       transaction isolation that are set           
                       by Connection.setAutoCommit() and            
                       Connection.setTransactionIsolation()         
                       and transaction state as maintained          
                       by the protocol, rather than                 
                       querying the database or blindly             
                       sending commands to the database             
                       for commit() or rollback() method            
                       calls?                                       
useReadAheadInput      Use newer, optimized non-blocking,   true    3.1.5
                       buffered input stream when reading           
                       from the server?                             

Debugging/Profiling

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
logger                 The name of a class that implements  com.mysql.jdbc.log.StandardLogger3.1.1
                       "com.mysql.jdbc.log.Log" that will           
                       be used to log messages to.                  
                       (default is                                  
                       "com.mysql.jdbc.log.StandardLogger",         
                       which logs to STDERR)                        
gatherPerfMetrics      Should the driver gather             false   3.1.2
                       performance metrics, and report              
                       them via the configured logger               
                       every 'reportMetricsIntervalMillis'          
                       milliseconds?                                
profileSQL             Trace queries and their              false   3.1.0
                       execution/fetch times to the                 
                       configured logger (true/false)               
                       defaults to 'false'                          
profileSql             Deprecated, use 'profileSQL'                 2.0.14
                       instead. Trace queries and their             
                       execution/fetch times on STDERR              
                       (true/false) defaults to 'false'             
reportMetricsIntervalMillisIf 'gatherPerfMetrics' is enabled,   30000   3.1.2
                       how often should they be logged (in          
                       ms)?                                         
maxQuerySizeToLog      Controls the maximum length/size of  2048    3.1.3
                       a query that will get logged when            
                       profiling or tracing                         
packetDebugBufferSize  The maximum number of packets to     20      3.1.3
                       retain when 'enablePacketDebug' is           
                       true                                         
slowQueryThresholdMillisIf 'logSlowQueries' is enabled, how  2000    3.1.2
                       long should a query (in ms) before           
                       it is logged as 'slow'?                      
slowQueryThresholdNanosIf 'useNanosForElapsedTime' is set   0       5.0.7
                       to true, and this property is set to         
                       a non-zero value, the driver will            
                       use this threshold (in nanosecond            
                       units) to determine if a query was           
                       slow.                                        
useUsageAdvisor        Should the driver issue 'usage'      false   3.1.1
                       warnings advising proper and                 
                       efficient usage of JDBC and MySQL            
                       Connector/J to the log (true/false,          
                       defaults to 'false')?                        
autoGenerateTestcaseScriptShould the driver dump the SQL it    false   3.1.9
                       is executing, including server-side          
                       prepared statements to STDERR?               
autoSlowLog            Instead of using                     true    5.1.4
                       slowQueryThreshold* to determine if          
                       a query is slow enough to be                 
                       logged, maintain statistics that             
                       allow the driver to determine                
                       queries that are outside the 99th            
                       percentile?                                  
clientInfoProvider     The name of a class that implements  com.mysql.jdbc.JDBC4CommentClientInfoProvider5.1.0
                       the                                          
                       com.mysql.jdbc.JDBC4ClientInfoProvider        
                       interface in order to support                
                       JDBC-4.0's                                   
                       Connection.get/setClientInfo()               
                       methods                                      
dumpMetadataOnColumnNotFoundShould the driver dump the           false   3.1.13
                       field-level metadata of a result             
                       set into the exception message when          
                       ResultSet.findColumn() fails?                
dumpQueriesOnException Should the driver dump the contents  false   3.1.3
                       of the query sent to the server in           
                       the message for SQLExceptions?               
enablePacketDebug      When enabled, a ring-buffer of       false   3.1.3
                       'packetDebugBufferSize' packets              
                       will be kept, and dumped when                
                       exceptions are thrown in key areas           
                       in the driver's code                         
explainSlowQueries     If 'logSlowQueries' is enabled,      false   3.1.2
                       should the driver automatically              
                       issue an 'EXPLAIN' on the server             
                       and send the results to the                  
                       configured log at a WARN level?              
includeInnodbStatusInDeadlockExceptionsInclude the output of "SHOW ENGINE   false   5.0.7
                       INNODB STATUS" in exception messages         
                       when deadlock exceptions are                 
                       detected?                                    
logSlowQueries         Should queries that take longer      false   3.1.2
                       than 'slowQueryThresholdMillis' be           
                       logged?                                      
logXaCommands          Should the driver log XA commands    false   5.0.5
                       sent by MysqlXaConnection to the             
                       server, at the DEBUG level of                
                       logging?                                     
profilerEventHandler   Name of a class that implements the  com.mysql.jdbc.profiler.LoggingProfilerEventHandler5.1.6
                       interface                                    
                       com.mysql.jdbc.profiler.ProfilerEventHandler        
                       that will be used to handle                  
                       profiling/tracing events.                    
resultSetSizeThreshold If the usage advisor is enabled,     100     5.0.5
                       how many rows should a result set            
                       contain before the driver warns              
                       that it is suspiciously large?               
traceProtocol          Should trace-level network protocol  false   3.1.2
                       be logged?                                   
useNanosForElapsedTime For profiling/debugging              false   5.0.7
                       functionality that measures elapsed          
                       time, should the driver try to use           
                       nanoseconds resolution if available          
                       (JDK >= 1.5)?                                

Miscellaneous

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
useUnicode             Should the driver use Unicode        true    1.1g
                       character encodings when handling            
                       strings?  Should only be used when           
                       the driver cannot determine the              
                       character set mapping, or you are            
                       trying to 'force' the driver to use          
                       a character set that MySQL either            
                       doesn't natively support (such as            
                       UTF-8), true/false, defaults to              
                       'true'                                       
characterEncoding      If 'useUnicode' is set to true,              1.1g
                       what character encoding should the           
                       driver use when dealing with                 
                       strings? (defaults is to                     
                       'autodetect')                                
characterSetResults    Character set to tell the server to          3.0.13
                       return results as.                           
connectionCollation    If set, tells the server to use              3.0.13
                       this collation via 'set                      
                       collation_connection'                        
useBlobToStoreUTF8OutsideBMPTells the driver to treat            false   5.1.3
                       [MEDIUM/LONG]BLOB columns as                 
                       [LONG]VARCHAR columns holding text           
                       encoded in UTF-8 that has                    
                       characters outside the BMP (4-byte           
                       encodings), which MySQL server               
                       cannot handle natively.                      
utf8OutsideBmpExcludedColumnNamePatternWhen "useBlobToStoreUTF8OutsideBMP"          5.1.3
                       is set to "true", column names               
                       matching the given regex will still          
                       be treated as BLOBs unless they              
                       match the regex specified for                
                       "utf8OutsideBmpIncludedColumnNamePattern".        
                       The regex must follow the patterns           
                       used for the java.util.regex                 
                       package.                                     
utf8OutsideBmpIncludedColumnNamePatternUsed to specify exclusion rules to           5.1.3
                       "utf8OutsideBmpExcludedColumnNamePattern".        
                       The regex must follow the patterns           
                       used for the java.util.regex                 
                       package.                                     
sessionVariables       A comma-separated list of                    3.1.8
                       name/value pairs to be sent as SET           
                       SESSION ...  to the server when the          
                       driver connects.                             
allowNanAndInf         Should the driver allow NaN or +/-   false   3.1.5
                       INF values in                                
                       PreparedStatement.setDouble()?               
autoClosePStmtStreams  Should the driver automatically      false   3.1.12
                       call .close() on streams/readers             
                       passed as arguments via set*()               
                       methods?                                     
autoDeserialize        Should the driver automatically      false   3.1.5
                       detect and de-serialize objects              
                       stored in BLOB fields?                       
blobsAreStrings        Should the driver always treat       false   5.0.8
                       BLOBs as Strings - specifically to           
                       work around dubious metadata                 
                       returned by the server for GROUP BY          
                       clauses?                                     
capitalizeTypeNames    Capitalize type names in             true    2.0.7
                       DatabaseMetaData? (usually only              
                       useful when using WebObjects,                
                       true/false, defaults to 'false')             
clobCharacterEncoding  The character encoding to use for            5.0.0
                       sending and retrieving TEXT,                 
                       MEDIUMTEXT and LONGTEXT values               
                       instead of the configured                    
                       connection characterEncoding                 
clobberStreamingResultsThis will cause a 'streaming'        false   3.0.9
                       ResultSet to be automatically                
                       closed, and any outstanding data             
                       still streaming from the server to           
                       be discarded if another query is             
                       executed before all the data has             
                       been read from the server.                   
continueBatchOnError   Should the driver continue           true    3.0.3
                       processing batch commands if one             
                       statement fails. The JDBC spec               
                       allows either way (defaults to               
                       'true').                                     
createDatabaseIfNotExistCreates the database given in the    false   3.1.9
                       URL if it doesn't yet exist. Assumes         
                       the configured user has permissions          
                       to create databases.                         
emptyStringsConvertToZeroShould the driver allow conversions  true    3.1.8
                       from empty string fields to numeric          
                       values of '0'?                               
emulateLocators        Should the driver emulate            false   3.1.0
                       java.sql.Blobs with locators? With           
                       this feature enabled, the driver             
                       will delay loading the actual Blob           
                       data until the one of the retrieval          
                       methods (getInputStream(),                   
                       getBytes(), and so forth) on the             
                       blob data stream has been accessed.          
                       For this to work, you must use a             
                       column alias with the value of the           
                       column to the actual name of the             
                       Blob. The feature also has the               
                       following restrictions: The SELECT           
                       that created the result set must             
                       reference only one table, the table          
                       must have a primary key; the SELECT          
                       must alias the original blob column          
                       name, specified as a string, to an           
                       alternate name; the SELECT must              
                       cover all columns that make up the           
                       primary key.                                 
emulateUnsupportedPstmtsShould the driver detect prepared    true    3.1.7
                       statements that are not supported by         
                       the server, and replace them with            
                       client-side emulated versions?               
functionsNeverReturnBlobsShould the driver always treat data  false   5.0.8
                       from functions returning BLOBs as            
                       Strings - specifically to work               
                       around dubious metadata returned by          
                       the server for GROUP BY clauses?             
generateSimpleParameterMetadataShould the driver generate           false   5.0.5
                       simplified parameter metadata for            
                       PreparedStatements when no metadata          
                       is available either because the              
                       server couldn't support preparing            
                       the statement, or server-side                
                       prepared statements are disabled?            
ignoreNonTxTables      Ignore non-transactional table       false   3.0.9
                       warning for rollback? (defaults to           
                       'false').                                    
jdbcCompliantTruncationShould the driver throw              true    3.1.2
                       java.sql.DataTruncation exceptions           
                       when data is truncated as is                 
                       required by the JDBC specification           
                       when connected to a server that              
                       supports warnings (MySQL 4.1.0 and           
                       newer)? This property has no effect          
                       if the server sql-mode includes              
                       STRICT_TRANS_TABLES.                         
maxRows                The maximum number of rows to        -1      all
                       return (0, the default means return          versions
                       all rows).                                   
netTimeoutForStreamingResultsWhat value should the driver         600     5.1.0
                       automatically set the server setting         
                       'net_write_timeout' to when the              
                       streaming result sets feature is in          
                       use? (value has unit of seconds,             
                       the value '0' means the driver will          
                       not try and adjust this value)               
noAccessToProcedureBodiesWhen determining procedure           false   5.0.3
                       parameter types for                          
                       CallableStatements, and the                  
                       connected user cannot access                 
                       procedure bodies through "SHOW               
                       CREATE PROCEDURE" or select on               
                       mysql.proc should the driver                 
                       instead create basic metadata (all           
                       parameters reported as IN VARCHARs,          
                       but allowing registerOutParameter()          
                       to be called on them anyway)                 
                       instead of throwing an exception?            
noDatetimeStringSync   Do not ensure that                   false   3.1.7
                       ResultSet.getDatetimeType().toString().equals(ResultSet.getString())        
noTimezoneConversionForTimeTypeDo not convert TIME values using     false   5.0.0
                       the server timezone if                       
                       'useTimezone'='true'                         
nullCatalogMeansCurrentWhen DatabaseMetadataMethods ask     true    3.1.8
                       for a 'catalog' parameter, does the          
                       value null mean use the current              
                       catalog? (this is not                        
                       JDBC-compliant, but follows legacy           
                       behavior from earlier versions of            
                       the driver)                                  
nullNamePatternMatchesAllShould DatabaseMetaData methods      true    3.1.8
                       that accept *pattern parameters              
                       treat null the same as '%' (this is          
                       not JDBC-compliant, however older            
                       versions of the driver accepted this         
                       departure from the specification)            
overrideSupportsIntegrityEnhancementFacilityShould the driver return "true" for  false   3.1.12
                       DatabaseMetaData.supportsIntegrityEnhancementFacility()        
                       even if the database doesn't                 
                       support it to workaround                     
                       applications that require this               
                       method to return "true" to signal            
                       support of foreign keys, even                
                       though the SQL specification states          
                       that this facility contains much             
                       more than just foreign key support           
                       (one such application being                  
                       OpenOffice)?                                 
padCharsWithSpace      If a result set column has the CHAR  false   5.0.6
                       type and the value does not fill the         
                       amount of characters specified in            
                       the DDL for the column, should the           
                       driver pad the remaining characters          
                       with space (for ANSI compliance)?            
pedantic               Follow the JDBC spec to the letter.  false   3.0.0
pinGlobalTxToPhysicalConnectionWhen using XAConnections, should     false   5.0.1
                       the driver ensure that operations            
                       on a given XID are always routed to          
                       the same physical connection? This           
                       allows the XAConnection to support           
                       "XA START ... JOIN" after "XA END"           
                       has been called                              
populateInsertRowWithDefaultValuesWhen using ResultSets that are       false   5.0.5
                       CONCUR_UPDATABLE, should the driver          
                       pre-populate the "insert" row with           
                       default values from the DDL for the          
                       table used in the query so those             
                       values are immediately available             
                       for ResultSet accessors? This                
                       functionality requires a call to             
                       the database for metadata each time          
                       a result set of this type is                 
                       created.  If disabled (the                   
                       default), the default values will be         
                       populated by the an internal call            
                       to refreshRow() which pulls back             
                       default values and/or values                 
                       changed by triggers.                         
processEscapeCodesForPrepStmtsShould the driver process escape     true    3.1.12
                       codes in queries that are prepared?          
relaxAutoCommit        If the version of MySQL the driver   false   2.0.13
                       connects to does not support                 
                       transactions, still allow calls to           
                       commit(), rollback() and                     
                       setAutoCommit() (true/false,                 
                       defaults to 'false')?                        
retainStatementAfterResultSetCloseShould the driver retain the         false   3.1.11
                       Statement reference in a ResultSet           
                       after ResultSet.close() has been             
                       called. This is not JDBC-compliant           
                       after JDBC-4.0.                              
rollbackOnPooledClose  Should the driver issue a            true    3.0.15
                       rollback() when the logical                  
                       connection in a pool is closed?              
runningCTS13           Enables workarounds for bugs in      false   3.1.7
                       Sun's JDBC compliance testsuite              
                       version 1.3                                  
serverTimezone         Override detection/mapping of                3.0.2
                       timezone. Used when timezone from            
                       server doesn't map to Java timezone          
statementInterceptors  A comma-delimited list of classes            5.1.1
                       that implement                               
                       "com.mysql.jdbc.StatementInterceptor"        
                       that should be placed "in between"           
                       query execution to influence the             
                       results. StatementInterceptors are           
                       "chainable", the results returned            
                       by the "current" interceptor will be         
                       passed on to the next in in the              
                       chain, from left-to-right order, as          
                       specified in this property.                  
strictFloatingPoint    Used only in older versions of       false   3.0.0
                       compliance test                              
strictUpdates          Should the driver do strict          true    3.0.4
                       checking (all primary keys                   
                       selected) of updatable result sets           
                       (true, false, defaults to 'true')?           
tinyInt1isBit          Should the driver treat the          true    3.0.16
                       datatype TINYINT(1) as the BIT type          
                       (because the server silently                 
                       converts BIT -> TINYINT(1) when              
                       creating tables)?                            
transformedBitIsBooleanIf the driver converts TINYINT(1)    false   3.1.9
                       to a different type, should it use           
                       BOOLEAN instead of BIT for future            
                       compatibility with MySQL-5.0, as             
                       MySQL-5.0 has a BIT type?                    
treatUtilDateAsTimestampShould the driver treat              true    5.0.5
                       java.util.Date as a TIMESTAMP for            
                       the purposes of                              
                       PreparedStatement.setObject()?               
ultraDevHack           Create PreparedStatements for        false   2.0.3
                       prepareCall() when required, because         
                       UltraDev is broken and issues a              
                       prepareCall() for _all_ statements?          
                       (true/false, defaults to 'false')            
useGmtMillisForDatetimesConvert between session timezone     false   3.1.12
                       and GMT before creating Date and             
                       Timestamp instances (value of                
                       "false" is legacy behavior, "true"           
                       leads to more JDBC-compliant                 
                       behavior.                                    
useHostsInPrivileges   Add '@hostname' to users in          true    3.0.2
                       DatabaseMetaData.getColumn/TablePrivileges()        
                       (true/false), defaults to 'true'.            
useInformationSchema   When connected to MySQL-5.0.7 or     false   5.0.0
                       newer, should the driver use the             
                       INFORMATION_SCHEMA to derive                 
                       information used by                          
                       DatabaseMetaData?                            
useJDBCCompliantTimezoneShiftShould the driver use                false   5.0.0
                       JDBC-compliant rules when converting         
                       TIME/TIMESTAMP/DATETIME values'              
                       timezone information for those JDBC          
                       arguments which take a                       
                       java.util.Calendar argument?                 
                       (Notice that this option is                  
                       exclusive of the "useTimezone=true"          
                       configuration option.)                       
useLegacyDatetimeCode  Use code for                         true    5.1.6
                       DATE/TIME/DATETIME/TIMESTAMP                 
                       handling in result sets and                  
                       statements that consistently                 
                       handles timezone conversions from            
                       client to server and back again, or          
                       use the legacy code for these                
                       datatypes that has been in the               
                       driver for backwards-compatibility?          
useOldAliasMetadataBehaviorShould the driver use the legacy     false   5.0.4
                       behavior for "AS" clauses on columns         
                       and tables, and only return aliases          
                       (if any) for                                 
                       ResultSetMetaData.getColumnName() or         
                       ResultSetMetaData.getTableName()             
                       rather than the original                     
                       column/table name? In 5.0.x, the             
                       default value was true.                      
useOldUTF8Behavior     Use the UTF-8 behavior the driver    false   3.1.6
                       did when communicating with 4.0 and          
                       older servers                                
useOnlyServerErrorMessagesDo not prepend 'standard' SQLState   true    3.0.15
                       error messages to error messages             
                       returned by the server.                      
useSSPSCompatibleTimezoneShiftIf migrating from an environment     false   5.0.5
                       that was using server-side prepared          
                       statements, and the configuration            
                       property                                     
                       "useJDBCCompliantTimeZoneShift" set          
                       to "true", use compatible behavior           
                       when not using server-side prepared          
                       statements when sending TIMESTAMP            
                       values to the MySQL server.                  
useServerPrepStmts     Use server-side prepared statements  false   3.1.0
                       if the server supports them?                 
useSqlStateCodes       Use SQL Standard state codes         true    3.1.3
                       instead of 'legacy' X/Open/SQL               
                       state codes (true/false), default            
                       is 'true'                                    
useStreamLengthsInPrepStmtsHonor stream length parameter in     true    3.0.2
                       PreparedStatement/ResultSet.setXXXStream()        
                       method calls (true/false, defaults           
                       to 'true')?                                  
useTimezone            Convert time/date types between      false   3.0.2
                       client and server timezones                  
                       (true/false, defaults to 'false')?           
useUnbufferedInput     Do not use BufferedInputStream for   true    3.0.11
                       reading data from the server                 
yearIsDateType         Should the JDBC driver treat the     true    3.1.9
                       MySQL type "YEAR" as a                       
                       java.sql.Date, or as a SHORT?                
zeroDateTimeBehavior   What should happen when the driver   exception3.1.4
                       encounters DATETIME values that are          
                       composed entirely of zeroes (used            
                       by MySQL to represent invalid                
                       dates)? Valid values are                     
                       "exception", "round" and                     
                       "convertToNull".                             

Connector/J also supports access to MySQL via named pipes on Windows
NT/2000/XP using the NamedPipeSocketFactory as a plugin-socket factory
via the socketFactory property. If you do not use a namedPipePath
property, the default of '\\.\pipe\MySQL' will be used. If you use the
`NamedPipeSocketFactory', the host name and port number values in the
JDBC url will be ignored. You can enable this feature using:

     socketFactory=com.mysql.jdbc.NamedPipeSocketFactory

Named pipes only work when connecting to a MySQL server on the same
physical machine as the one the JDBC driver is being used on. In simple
performance tests, it appears that named pipe access is between 30%-50%
faster than the standard TCP/IP access. However, this varies per
system, and named pipes are slower than TCP/IP in many Windows
configurations.

You can create your own socket factories by following the example code
in com.mysql.jdbc.NamedPipeSocketFactory, or
com.mysql.jdbc.StandardSocketFactory.


File: manual.info,  Node: connector-j-reference-implementation-notes,  Next: connector-j-reference-type-conversions,  Prev: connector-j-reference-configuration-properties,  Up: connector-j-reference

20.4.4.2 JDBC API Implementation Notes
......................................

MySQL Connector/J passes all of the tests in the publicly-available
version of Sun's JDBC compliance test suite.  However, in many places
the JDBC specification is vague about how certain functionality should
be implemented, or the specification allows leeway in implementation.

This section gives details on a interface-by-interface level about how
certain implementation decisions may affect how you use MySQL
Connector/J.

   * *Blob*

     Starting with Connector/J version 3.1.0, you can emulate Blobs
     with locators by adding the property 'emulateLocators=true' to
     your JDBC URL. Using this method, the driver will delay loading
     the actual Blob data until you retrieve the other data and then
     use retrieval methods (`getInputStream()', `getBytes()', and so
     forth) on the blob data stream.

     For this to work, you must use a column alias with the value of
     the column to the actual name of the Blob, for example:

          SELECT id, 'data' as blob_data from blobtable

     For this to work, you must also follow these rules:

        * The *Note `SELECT': select. must also reference only one
          table, the table must have a primary key.

        * The *Note `SELECT': select. must alias the original blob
          column name, specified as a string, to an alternate name.

        * The *Note `SELECT': select. must cover all columns that make
          up the primary key.

     The Blob implementation does not allow in-place modification (they
     are copies, as reported by the
     `DatabaseMetaData.locatorsUpdateCopies()' method). Because of
     this, you should use the corresponding
     `PreparedStatement.setBlob()' or `ResultSet.updateBlob()' (in the
     case of updatable result sets) methods to save changes back to the
     database.

     MySQL Enterprise

     MySQL Enterprise subscribers will find more information about type
     conversion in the Knowledge Base article, Type Conversions
     Supported by MySQL Connector/J
     (https://kb.mysql.com/view.php?id=4929). To subscribe to MySQL
     Enterprise see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   * *CallableStatement*

     Starting with Connector/J 3.1.1, stored procedures are supported
     when connecting to MySQL version 5.0 or newer via the
     CallableStatement interface.  Currently, the
     `getParameterMetaData()' method of CallableStatement is not
     supported.

   * *Clob*

     The Clob implementation does not allow in-place modification (they
     are copies, as reported by the
     `DatabaseMetaData.locatorsUpdateCopies()' method). Because of
     this, you should use the `PreparedStatement.setClob()' method to
     save changes back to the database. The JDBC API does not have a
     `ResultSet.updateClob()' method.

   * *Connection*

     Unlike older versions of MM.MySQL the `isClosed()' method does not
     ping the server to determine if it is alive. In accordance with the
     JDBC specification, it only returns true if `closed()' has been
     called on the connection. If you need to determine if the
     connection is still valid, you should issue a simple query, such as
     `SELECT 1'. The driver will throw an exception if the connection
     is no longer valid.

   * *DatabaseMetaData*

     Foreign Key information (`getImportedKeys()'/`getExportedKeys()'
     and `getCrossReference()') is only available from InnoDB tables.
     However, the driver uses *Note `SHOW CREATE TABLE':
     show-create-table. to retrieve this information, so when other
     storage engines support foreign keys, the driver will
     transparently support them as well.

   * *PreparedStatement*

     PreparedStatements are implemented by the driver, as MySQL does
     not have a prepared statement feature. Because of this, the driver
     does not implement `getParameterMetaData()' or `getMetaData()' as
     it would require the driver to have a complete SQL parser in the
     client.

     Starting with version 3.1.0 MySQL Connector/J, server-side
     prepared statements and binary-encoded result sets are used when
     the server supports them.

     Take care when using a server-side prepared statement with *large*
     parameters that are set via `setBinaryStream()',
     `setAsciiStream()', `setUnicodeStream()', `setBlob()', or
     `setClob()'. If you want to re-execute the statement with any
     large parameter changed to a non-large parameter, it is necessary
     to call `clearParameters()' and set all parameters again. The
     reason for this is as follows:

        * During both server-side prepared statements and client-side
          emulation, large data is exchanged only when
          `PreparedStatement.execute()' is called.

        * Once that has been done, the stream used to read the data on
          the client side is closed (as per the JDBC spec), and cannot
          be read from again.

        * If a parameter changes from large to non-large, the driver
          must reset the server-side state of the prepared statement to
          allow the parameter that is being changed to take the place
          of the prior large value. This removes all of the large data
          that has already been sent to the server, thus requiring the
          data to be re-sent, via the `setBinaryStream()',
          `setAsciiStream()', `setUnicodeStream()', `setBlob()' or
          `setClob()' methods.

     Consequently, if you want to change the type of a parameter to a
     non-large one, you must call `clearParameters()' and set all
     parameters of the prepared statement again before it can be
     re-executed.

   * *ResultSet*

     By default, ResultSets are completely retrieved and stored in
     memory. In most cases this is the most efficient way to operate,
     and due to the design of the MySQL network protocol is easier to
     implement. If you are working with ResultSets that have a large
     number of rows or large values, and can not allocate heap space in
     your JVM for the memory required, you can tell the driver to
     stream the results back one row at a time.

     To enable this functionality, you need to create a Statement
     instance in the following manner:

          stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
                        java.sql.ResultSet.CONCUR_READ_ONLY);
          stmt.setFetchSize(Integer.MIN_VALUE);

     The combination of a forward-only, read-only result set, with a
     fetch size of `Integer.MIN_VALUE' serves as a signal to the driver
     to stream result sets row-by-row. After this any result sets
     created with the statement will be retrieved row-by-row.

     There are some caveats with this approach. You will have to read
     all of the rows in the result set (or close it) before you can
     issue any other queries on the connection, or an exception will be
     thrown.

     The earliest the locks these statements hold can be released
     (whether they be `MyISAM' table-level locks or row-level locks in
     some other storage engine such as `InnoDB') is when the statement
     completes.

     If the statement is within scope of a transaction, then locks are
     released when the transaction completes (which implies that the
     statement needs to complete first). As with most other databases,
     statements are not complete until all the results pending on the
     statement are read or the active result set for the statement is
     closed.

     Therefore, if using streaming results, you should process them as
     quickly as possible if you want to maintain concurrent access to
     the tables referenced by the statement producing the result set.

   * *ResultSetMetaData*

     The `isAutoIncrement()' method only works when using MySQL servers
     4.0 and newer.

   * *Statement*

     When using versions of the JDBC driver earlier than 3.2.1, and
     connected to server versions earlier than 5.0.3, the
     `setFetchSize()' method has no effect, other than to toggle result
     set streaming as described above.

     Connector/J 5.0.0 and later include support for both
     `Statement.cancel()' and `Statement.setQueryTimeout()'. Both
     require MySQL 5.0.0 or newer server, and require a separate
     connection to issue the *Note `KILL QUERY': kill.  statement. In
     the case of `setQueryTimeout()', the implementation creates an
     additional thread to handle the timeout functionality.

     *Note*:

     Failures to cancel the statement for `setQueryTimeout()' may
     manifest themselves as `RuntimeException' rather than failing
     silently, as there is currently no way to unblock the thread that
     is executing the query being cancelled due to timeout expiration
     and have it throw the exception instead.

     MySQL does not support SQL cursors, and the JDBC driver doesn't
     emulate them, so "setCursorName()" has no effect.

     Connector/J 5.1.3 and later include two additional methods:

        * `setLocalInfileInputStream()' sets an `InputStream' instance
          that will be used to send data to the MySQL server for a
          *Note `LOAD DATA LOCAL INFILE': load-data. statement rather
          than a `FileInputStream' or `URLInputStream' that represents
          the path given as an argument to the statement.

          This stream will be read to completion upon execution of a
          *Note `LOAD DATA LOCAL INFILE': load-data. statement, and
          will automatically be closed by the driver, so it needs to be
          reset before each call to `execute*()' that would cause the
          MySQL server to request data to fulfill the request for *Note
          `LOAD DATA LOCAL INFILE': load-data.

          If this value is set to `NULL', the driver will revert to
          using a `FileInputStream' or `URLInputStream' as required.

        * `getLocalInfileInputStream()' returns the `InputStream'
          instance that will be used to send data in response to a
          *Note `LOAD DATA LOCAL INFILE': load-data. statement.

          This method returns `NULL' if no such stream has been set via
          `setLocalInfileInputStream()'.


File: manual.info,  Node: connector-j-reference-type-conversions,  Next: connector-j-reference-charsets,  Prev: connector-j-reference-implementation-notes,  Up: connector-j-reference

20.4.4.3 Java, JDBC and MySQL Types
...................................

MySQL Connector/J is flexible in the way it handles conversions between
MySQL data types and Java data types.

In general, any MySQL data type can be converted to a java.lang.String,
and any numerical type can be converted to any of the Java numerical
types, although round-off, overflow, or loss of precision may occur.

Starting with Connector/J 3.1.0, the JDBC driver will issue warnings or
throw DataTruncation exceptions as is required by the JDBC
specification unless the connection was configured not to do so by
using the property jdbcCompliantTruncation and setting it to `false'.

The conversions that are always guaranteed to work are listed in the
following table:

Connection Properties - Miscellaneous

*These MySQL Data Types*             *Can always be converted to these
                                     Java types*
`CHAR, VARCHAR, BLOB, TEXT, ENUM,    `java.lang.String,
and SET'                             java.io.InputStream, java.io.Reader,
                                     java.sql.Blob, java.sql.Clob'
`FLOAT, REAL, DOUBLE PRECISION,      `java.lang.String, java.lang.Short,
NUMERIC, DECIMAL, TINYINT,           java.lang.Integer, java.lang.Long,
SMALLINT, MEDIUMINT, INTEGER,        java.lang.Double,
BIGINT'                              java.math.BigDecimal'
`DATE, TIME, DATETIME, TIMESTAMP'    `java.lang.String, java.sql.Date,
                                     java.sql.Timestamp'

*Note*:

Round-off, overflow or loss of precision may occur if you choose a Java
numeric data type that has less precision or capacity than the MySQL
data type you are converting to/from.

The ResultSet.getObject() method uses the type conversions between
MySQL and Java types, following the JDBC specification where
appropriate. The value returned by
ResultSetMetaData.GetColumnClassName() is also shown below. For more
information on the `java.sql.Types' classes see Java 2 Platform Types
(http://java.sun.com/j2se/1.4.2/docs/api/java/sql/Types.html).

MySQL Types to Java Types for ResultSet.getObject()

*MySQL Type Name*  *Return value of   *Returned as Java Class*
                   `GetColumnClassName'*
BIT(1) (new in     BIT                java.lang.Boolean
MySQL-5.0)                            
BIT( > 1) (new in  BIT                byte[]
MySQL-5.0)                            
TINYINT            TINYINT            java.lang.Boolean if the
                                      configuration property
                                      `tinyInt1isBit' is set to `true'
                                      (the default) and the storage size
                                      is 1, or java.lang.Integer if not.
BOOL, BOOLEAN      TINYINT            See TINYINT, above as these are
                                      aliases for TINYINT(1), currently.
SMALLINT[(M)]      SMALLINT           java.lang.Integer (regardless if
[UNSIGNED]         [UNSIGNED]         UNSIGNED or not)
MEDIUMINT[(M)]     MEDIUMINT          java.lang.Integer, if UNSIGNED
[UNSIGNED]         [UNSIGNED]         java.lang.Long (C/J 3.1 and
                                      earlier), or java.lang.Integer for
                                      C/J 5.0 and later
INT,INTEGER[(M)]   INTEGER [UNSIGNED] java.lang.Integer, if UNSIGNED
[UNSIGNED]                            java.lang.Long
BIGINT[(M)]        BIGINT [UNSIGNED]  java.lang.Long, if UNSIGNED
[UNSIGNED]                            java.math.BigInteger
FLOAT[(M,D)]       FLOAT              java.lang.Float
DOUBLE[(M,B)]      DOUBLE             java.lang.Double
DECIMAL[(M[,D])]   DECIMAL            java.math.BigDecimal
DATE               DATE               java.sql.Date
DATETIME           DATETIME           java.sql.Timestamp
TIMESTAMP[(M)]     TIMESTAMP          java.sql.Timestamp
TIME               TIME               java.sql.Time
YEAR[(2|4)]        YEAR               If `yearIsDateType' configuration
                                      property is set to false, then the
                                      returned object type is
                                      java.sql.Short. If set to true (the
                                      default) then an object of type
                                      java.sql.Date (with the date set to
                                      January 1st, at midnight).
CHAR(M)            CHAR               java.lang.String (unless the
                                      character set for the column is
                                      BINARY, then byte[] is returned.
VARCHAR(M)         VARCHAR            java.lang.String (unless the
[BINARY]                              character set for the column is
                                      BINARY, then byte[] is returned.
BINARY(M)          BINARY             byte[]
VARBINARY(M)       VARBINARY          byte[]
TINYBLOB           TINYBLOB           byte[]
TINYTEXT           VARCHAR            java.lang.String
BLOB               BLOB               byte[]
TEXT               VARCHAR            java.lang.String
MEDIUMBLOB         MEDIUMBLOB         byte[]
MEDIUMTEXT         VARCHAR            java.lang.String
LONGBLOB           LONGBLOB           byte[]
LONGTEXT           VARCHAR            java.lang.String
ENUM('value1','value2',...)CHAR               java.lang.String
SET('value1','value2',...)CHAR               java.lang.String


File: manual.info,  Node: connector-j-reference-charsets,  Next: connector-j-reference-using-ssl,  Prev: connector-j-reference-type-conversions,  Up: connector-j-reference

20.4.4.4 Using Character Sets and Unicode
.........................................

All strings sent from the JDBC driver to the server are converted
automatically from native Java Unicode form to the client character
encoding, including all queries sent via `Statement.execute()',
`Statement.executeUpdate()', `Statement.executeQuery()' as well as all

PreparedStatement

and

CallableStatement

parameters with the exclusion of parameters set using `setBytes()',
`setBinaryStream()', `setAsciiStream()', `setUnicodeStream()' and
`setBlob()'.

Prior to MySQL Server 4.1, Connector/J supported a single character
encoding per connection, which could either be automatically detected
from the server configuration, or could be configured by the user
through the useUnicode and characterEncoding properties.

Starting with MySQL Server 4.1, Connector/J supports a single character
encoding between client and server, and any number of character
encodings for data returned by the server to the client in ResultSets.

The character encoding between client and server is automatically
detected upon connection. The encoding used by the driver is specified
on the server via the `character_set'
(http://dev.mysql.com/doc/refman/4.1/en/server-system-variables.html#sysvar_character_set)
system variable for server versions older than 4.1.0 and
`character_set_server' for server versions 4.1.0 and newer. For more
information, see *Note charset-server::.

To override the automatically-detected encoding on the client side, use
the characterEncoding property in the URL used to connect to the server.

When specifying character encodings on the client side, Java-style
names should be used. The following table lists Java-style names for
MySQL character sets:

MySQL to Java Encoding Name Translations

*MySQL Character Set Name*           *Java-Style Character Encoding Name*
ascii                                US-ASCII
big5                                 Big5
gbk                                  GBK
sjis                                 SJIS (or Cp932 or MS932 for MySQL
                                     Server < 4.1.11)
cp932                                Cp932 or MS932 (MySQL Server >
                                     4.1.11)
gb2312                               EUC_CN
ujis                                 EUC_JP
euckr                                EUC_KR
latin1                               ISO8859_1
latin2                               ISO8859_2
greek                                ISO8859_7
hebrew                               ISO8859_8
cp866                                Cp866
tis620                               TIS620
cp1250                               Cp1250
cp1251                               Cp1251
cp1257                               Cp1257
macroman                             MacRoman
macce                                MacCentralEurope
utf8                                 UTF-8
ucs2                                 UnicodeBig

*Warning*:

Do not issue the query 'set names' with Connector/J, as the driver will
not detect that the character set has changed, and will continue to use
the character set detected during the initial connection setup.

To allow multiple character sets to be sent from the client, the UTF-8
encoding should be used, either by configuring `utf8' as the default
server character set, or by configuring the JDBC driver to use UTF-8
through the characterEncoding property.


File: manual.info,  Node: connector-j-reference-using-ssl,  Next: connector-j-reference-replication-connection,  Prev: connector-j-reference-charsets,  Up: connector-j-reference

20.4.4.5 Connecting Securely Using SSL
......................................

SSL in MySQL Connector/J encrypts all data (other than the initial
handshake) between the JDBC driver and the server. The performance
penalty for enabling SSL is an increase in query processing time
between 35% and 50%, depending on the size of the query, and the amount
of data it returns.

For SSL Support to work, you must have the following:

   * A JDK that includes JSSE (Java Secure Sockets Extension), like
     JDK-1.4.1 or newer. SSL does not currently work with a JDK that
     you can add JSSE to, like JDK-1.2.x or JDK-1.3.x due to the
     following JSSE bug:
     `http://developer.java.sun.com/developer/bugParade/bugs/4273544.html'

   * A MySQL server that supports SSL and has been compiled and
     configured to do so, which is MySQL-4.0.4 or later, see *Note
     secure-connections::, for more information.

   * A client certificate (covered later in this section)

The system works through two Java truststore files, one file contains
the certificate information for the server (`truststore' in the
examples below). The other file contains the certificate for the client
(`keystore' in the examples below). All Java truststore files are
password protected by supplying a suitable password to the `keytool'
when you create the files. You need the file names and associated
passwords to create an SSL connection.

You will first need to import the MySQL server CA Certificate into a
Java truststore. A sample MySQL server CA Certificate is located in the
`SSL' subdirectory of the MySQL source distribution. This is what SSL
will use to determine if you are communicating with a secure MySQL
server.  Alternatively, use the CA Certificate that you have generated
or been provided with by your SSL provider.

To use Java's `keytool' to create a truststore in the current directory
, and import the server's CA certificate (`cacert.pem'), you can do the
following (assuming that `keytool' is in your path. The `keytool'
should be located in the `bin' subdirectory of your JDK or JRE):

     shell> keytool -import -alias mysqlServerCACert \
                                       -file cacert.pem -keystore truststore

You will need to enter the password when prompted for the keystore
file. Interaction with `keytool' will look like this:

     Enter keystore password:  *********
     Owner: EMAILADDRESS=walrus@example.com, CN=Walrus,
            O=MySQL AB, L=Orenburg, ST=Some-State, C=RU
     Issuer: EMAILADDRESS=walrus@example.com, CN=Walrus,
            O=MySQL AB, L=Orenburg, ST=Some-State, C=RU
     Serial number: 0
     Valid from:
        Fri Aug 02 16:55:53 CDT 2002 until: Sat Aug 02 16:55:53 CDT 2003
     Certificate fingerprints:
         MD5:  61:91:A0:F2:03:07:61:7A:81:38:66:DA:19:C4:8D:AB
         SHA1: 25:77:41:05:D5:AD:99:8C:14:8C:CA:68:9C:2F:B8:89:C3:34:4D:6C
     Trust this certificate? [no]:  yes
     Certificate was added to keystore

You then have two options, you can either import the client certificate
that matches the CA certificate you just imported, or you can create a
new client certificate.

To import an existing certificate, the certificate should be in DER
format. You can use `openssl' to convert an existing certificate into
the new format. For example:

     shell> openssl x509 -outform DER -in client-cert.pem -out client.cert

You now need to import the converted certificate into your keystore
using `keytool':

     shell> keytool -import -file client.cert -keystore keystore -alias mysqlClientCertificate

To generate your own client certificate, use `keytool' to create a
suitable certificate and add it to the `keystore' file:

      shell> keytool -genkey -keyalg rsa \
          -alias mysqlClientCertificate -keystore keystore

Keytool will prompt you for the following information, and create a
keystore named `keystore' in the current directory.

You should respond with information that is appropriate for your
situation:

     Enter keystore password:  *********
     What is your first and last name?
       [Unknown]:  Matthews
     What is the name of your organizational unit?
       [Unknown]:  Software Development
     What is the name of your organization?
       [Unknown]:  MySQL AB
     What is the name of your City or Locality?
       [Unknown]:  Flossmoor
     What is the name of your State or Province?
       [Unknown]:  IL
     What is the two-letter country code for this unit?
       [Unknown]:  US
     Is <CN=Matthews, OU=Software Development, O=MySQL AB,
      L=Flossmoor, ST=IL, C=US> correct?
       [no]:  y

     Enter key password for <mysqlClientCertificate>
             (RETURN if same as keystore password):

Finally, to get JSSE to use the keystore and truststore that you have
generated, you need to set the following system properties when you
start your JVM, replacing path_to_keystore_file with the full path to
the keystore file you created, path_to_truststore_file with the path to
the truststore file you created, and using the appropriate password
values for each property. You can do this either on the command line:

     -Djavax.net.ssl.keyStore=path_to_keystore_file
     -Djavax.net.ssl.keyStorePassword=password
     -Djavax.net.ssl.trustStore=path_to_truststore_file
     -Djavax.net.ssl.trustStorePassword=password

Or you can set the values directly within the application:

      System.setProperty("javax.net.ssl.keyStore","path_to_keystore_file");
     System.setProperty("javax.net.ssl.keyStorePassword","password");
     System.setProperty("javax.net.ssl.trustStore","path_to_truststore_file");
     System.setProperty("javax.net.ssl.trustStorePassword","password");

You will also need to set useSSL to `true' in your connection
parameters for MySQL Connector/J, either by adding `useSSL=true' to
your URL, or by setting the property useSSL to `true' in the
java.util.Properties instance you pass to
`DriverManager.getConnection()'.

You can test that SSL is working by turning on JSSE debugging (as
detailed below), and look for the following key events:

     ...
     *** ClientHello, v3.1
     RandomCookie:  GMT: 1018531834 bytes = { 199, 148, 180, 215, 74, 12, »
       54, 244, 0, 168, 55, 103, 215, 64, 16, 138, 225, 190, 132, 153, 2, »
       217, 219, 239, 202, 19, 121, 78 }
     Session ID:  {}
     Cipher Suites:  { 0, 5, 0, 4, 0, 9, 0, 10, 0, 18, 0, 19, 0, 3, 0, 17 }
     Compression Methods:  { 0 }
     ***
     [write] MD5 and SHA1 hashes:  len = 59
     0000: 01 00 00 37 03 01 3D B6 90 FA C7 94 B4 D7 4A 0C  ...7..=.......J.
     0010: 36 F4 00 A8 37 67 D7 40 10 8A E1 BE 84 99 02 D9  6...7g.@........
     0020: DB EF CA 13 79 4E 00 00 10 00 05 00 04 00 09 00  ....yN..........
     0030: 0A 00 12 00 13 00 03 00 11 01 00                 ...........
     main, WRITE:  SSL v3.1 Handshake, length = 59
     main, READ:  SSL v3.1 Handshake, length = 74
     *** ServerHello, v3.1
     RandomCookie:  GMT: 1018577560 bytes = { 116, 50, 4, 103, 25, 100, 58, »
        202, 79, 185, 178, 100, 215, 66, 254, 21, 83, 187, 190, 42, 170, 3, »
        132, 110, 82, 148, 160, 92 }
     Session ID:  {163, 227, 84, 53, 81, 127, 252, 254, 178, 179, 68, 63, »
        182, 158, 30, 11, 150, 79, 170, 76, 255, 92, 15, 226, 24, 17, 177, »
        219, 158, 177, 187, 143}
     Cipher Suite:  { 0, 5 }
     Compression Method: 0
     ***
     %% Created:  [Session-1, SSL_RSA_WITH_RC4_128_SHA]
     ** SSL_RSA_WITH_RC4_128_SHA
     [read] MD5 and SHA1 hashes:  len = 74
     0000: 02 00 00 46 03 01 3D B6 43 98 74 32 04 67 19 64  ...F..=.C.t2.g.d
     0010: 3A CA 4F B9 B2 64 D7 42 FE 15 53 BB BE 2A AA 03  :.O..d.B..S..*..
     0020: 84 6E 52 94 A0 5C 20 A3 E3 54 35 51 7F FC FE B2  .nR..\ ..T5Q....
     0030: B3 44 3F B6 9E 1E 0B 96 4F AA 4C FF 5C 0F E2 18  .D?.....O.L.\...
     0040: 11 B1 DB 9E B1 BB 8F 00 05 00                    ..........
     main, READ:  SSL v3.1 Handshake, length = 1712
     ...

JSSE provides debugging (to STDOUT) when you set the following system
property: `-Djavax.net.debug=all' This will tell you what keystores and
truststores are being used, as well as what is going on during the SSL
handshake and certificate exchange. It will be helpful when trying to
determine what is not working when trying to get an SSL connection to
happen.


File: manual.info,  Node: connector-j-reference-replication-connection,  Next: connector-j-reference-error-sqlstates,  Prev: connector-j-reference-using-ssl,  Up: connector-j-reference

20.4.4.6 Using Master/Slave Replication with ReplicationConnection
..................................................................

Starting with Connector/J 3.1.7, we've made available a variant of the
driver that will automatically send queries to a read/write master, or
a failover or round-robin loadbalanced set of slaves based on the state
of `Connection.getReadOnly()' .

An application signals that it wants a transaction to be read-only by
calling `Connection.setReadOnly(true)', this replication-aware
connection will use one of the slave connections, which are
load-balanced per-vm using a round-robin scheme (a given connection is
sticky to a slave unless that slave is removed from service). If you
have a write transaction, or if you have a read that is time-sensitive
(remember, replication in MySQL is asynchronous), set the connection to
be not read-only, by calling `Connection.setReadOnly(false)' and the
driver will ensure that further calls are sent to the master MySQL
server. The driver takes care of propagating the current state of
autocommit, isolation level, and catalog between all of the connections
that it uses to accomplish this load balancing functionality.

To enable this functionality, use the "
`com.mysql.jdbc.ReplicationDriver' " class when configuring your
application server's connection pool or when creating an instance of a
JDBC driver for your standalone application. Because it accepts the
same URL format as the standard MySQL JDBC driver, `ReplicationDriver'
does not currently work with `java.sql.DriverManager' -based connection
creation unless it is the only MySQL JDBC driver registered with the
`DriverManager' .

Here is a short, simple example of how ReplicationDriver might be used
in a standalone application.

     import java.sql.Connection;
     import java.sql.ResultSet;
     import java.util.Properties;

     import com.mysql.jdbc.ReplicationDriver;

     public class ReplicationDriverDemo {

       public static void main(String[] args) throws Exception {
         ReplicationDriver driver = new ReplicationDriver();

         Properties props = new Properties();

         // We want this for failover on the slaves
         props.put("autoReconnect", "true");

         // We want to load balance between the slaves
         props.put("roundRobinLoadBalance", "true");

         props.put("user", "foo");
         props.put("password", "bar");

         //
         // Looks like a normal MySQL JDBC url, with a
         // comma-separated list of hosts, the first
         // being the 'master', the rest being any number
         // of slaves that the driver will load balance against
         //

         Connection conn =
             driver.connect("jdbc:mysql://master,slave1,slave2,slave3/test",
                 props);

         //
         // Perform read/write work on the master
         // by setting the read-only flag to "false"
         //

         conn.setReadOnly(false);
         conn.setAutoCommit(false);
         conn.createStatement().executeUpdate("UPDATE some_table ....");
         conn.commit();

         //
         // Now, do a query from a slave, the driver automatically picks one
         // from the list
         //

         conn.setReadOnly(true);

         ResultSet rs =
           conn.createStatement().executeQuery("SELECT a,b FROM alt_table");

          .......
       }
     }

You may also want to investigate the Load Balancing JDBC Pool (lbpol)
tool, which provides a wrapper around the standard JDBC driver and
allows you to use DB connection pools that includes checks for system
failures and uneven load distribution. For more information, see Load
Balancing JDBC Pool (lbpool) (http://code.tailrank.com/lbpool).


File: manual.info,  Node: connector-j-reference-error-sqlstates,  Prev: connector-j-reference-replication-connection,  Up: connector-j-reference

20.4.4.7 Mapping MySQL Error Numbers to SQLStates
.................................................

The table below provides a mapping of the MySQL Error Numbers to `SQL
States'

*Mapping of MySQL Error Numbers to SQLStates*

MySQL Error    MySQL Error Name              Legacy         SQL Standard
Number                                       (X/Open)       SQLState
                                             SQLState       
1022           ER_DUP_KEY                    S1000          23000
1037           ER_OUTOFMEMORY                S1001          HY001
1038           ER_OUT_OF_SORTMEMORY          S1001          HY001
1040           ER_CON_COUNT_ERROR            08004          08004
1042           ER_BAD_HOST_ERROR             08004          08S01
1043           ER_HANDSHAKE_ERROR            08004          08S01
1044           ER_DBACCESS_DENIED_ERROR      S1000          42000
1045           ER_ACCESS_DENIED_ERROR        28000          28000
1047           ER_UNKNOWN_COM_ERROR          08S01          HY000
1050           ER_TABLE_EXISTS_ERROR         S1000          42S01
1051           ER_BAD_TABLE_ERROR            42S02          42S02
1052           ER_NON_UNIQ_ERROR             S1000          23000
1053           ER_SERVER_SHUTDOWN            S1000          08S01
1054           ER_BAD_FIELD_ERROR            S0022          42S22
1055           ER_WRONG_FIELD_WITH_GROUP     S1009          42000
1056           ER_WRONG_GROUP_FIELD          S1009          42000
1057           ER_WRONG_SUM_SELECT           S1009          42000
1058           ER_WRONG_VALUE_COUNT          21S01          21S01
1059           ER_TOO_LONG_IDENT             S1009          42000
1060           ER_DUP_FIELDNAME              S1009          42S21
1061           ER_DUP_KEYNAME                S1009          42000
1062           ER_DUP_ENTRY                  S1009          23000
1063           ER_WRONG_FIELD_SPEC           S1009          42000
1064           ER_PARSE_ERROR                42000          42000
1065           ER_EMPTY_QUERY                42000          42000
1066           ER_NONUNIQ_TABLE              S1009          42000
1067           ER_INVALID_DEFAULT            S1009          42000
1068           ER_MULTIPLE_PRI_KEY           S1009          42000
1069           ER_TOO_MANY_KEYS              S1009          42000
1070           ER_TOO_MANY_KEY_PARTS         S1009          42000
1071           ER_TOO_LONG_KEY               S1009          42000
1072           ER_KEY_COLUMN_DOES_NOT_EXITS  S1009          42000
1073           ER_BLOB_USED_AS_KEY           S1009          42000
1074           ER_TOO_BIG_FIELDLENGTH        S1009          42000
1075           ER_WRONG_AUTO_KEY             S1009          42000
1080           ER_FORCING_CLOSE              S1000          08S01
1081           ER_IPSOCK_ERROR               08S01          08S01
1082           ER_NO_SUCH_INDEX              S1009          42S12
1083           ER_WRONG_FIELD_TERMINATORS    S1009          42000
1084           ER_BLOBS_AND_NO_TERMINATED    S1009          42000
1090           ER_CANT_REMOVE_ALL_FIELDS     S1000          42000
1091           ER_CANT_DROP_FIELD_OR_KEY     S1000          42000
1101           ER_BLOB_CANT_HAVE_DEFAULT     S1000          42000
1102           ER_WRONG_DB_NAME              S1000          42000
1103           ER_WRONG_TABLE_NAME           S1000          42000
1104           ER_TOO_BIG_SELECT             S1000          42000
1106           ER_UNKNOWN_PROCEDURE          S1000          42000
1107           ER_WRONG_PARAMCOUNT_TO_PROCEDURES1000          42000
1109           ER_UNKNOWN_TABLE              S1000          42S02
1110           ER_FIELD_SPECIFIED_TWICE      S1000          42000
1112           ER_UNSUPPORTED_EXTENSION      S1000          42000
1113           ER_TABLE_MUST_HAVE_COLUMNS    S1000          42000
1115           ER_UNKNOWN_CHARACTER_SET      S1000          42000
1118           ER_TOO_BIG_ROWSIZE            S1000          42000
1120           ER_WRONG_OUTER_JOIN           S1000          42000
1121           ER_NULL_COLUMN_IN_INDEX       S1000          42000
1129           ER_HOST_IS_BLOCKED            08004          HY000
1130           ER_HOST_NOT_PRIVILEGED        08004          HY000
1131           ER_PASSWORD_ANONYMOUS_USER    S1000          42000
1132           ER_PASSWORD_NOT_ALLOWED       S1000          42000
1133           ER_PASSWORD_NO_MATCH          S1000          42000
1136           ER_WRONG_VALUE_COUNT_ON_ROW   S1000          21S01
1138           ER_INVALID_USE_OF_NULL        S1000          42000
1139           ER_REGEXP_ERROR               S1000          42000
1140           ER_MIX_OF_GROUP_FUNC_AND_FIELDSS1000          42000
1141           ER_NONEXISTING_GRANT          S1000          42000
1142           ER_TABLEACCESS_DENIED_ERROR   S1000          42000
1143           ER_COLUMNACCESS_DENIED_ERROR  S1000          42000
1144           ER_ILLEGAL_GRANT_FOR_TABLE    S1000          42000
1145           ER_GRANT_WRONG_HOST_OR_USER   S1000          42000
1146           ER_NO_SUCH_TABLE              S1000          42S02
1147           ER_NONEXISTING_TABLE_GRANT    S1000          42000
1148           ER_NOT_ALLOWED_COMMAND        S1000          42000
1149           ER_SYNTAX_ERROR               S1000          42000
1152           ER_ABORTING_CONNECTION        S1000          08S01
1153           ER_NET_PACKET_TOO_LARGE       S1000          08S01
1154           ER_NET_READ_ERROR_FROM_PIPE   S1000          08S01
1155           ER_NET_FCNTL_ERROR            S1000          08S01
1156           ER_NET_PACKETS_OUT_OF_ORDER   S1000          08S01
1157           ER_NET_UNCOMPRESS_ERROR       S1000          08S01
1158           ER_NET_READ_ERROR             S1000          08S01
1159           ER_NET_READ_INTERRUPTED       S1000          08S01
1160           ER_NET_ERROR_ON_WRITE         S1000          08S01
1161           ER_NET_WRITE_INTERRUPTED      S1000          08S01
1162           ER_TOO_LONG_STRING            S1000          42000
1163           ER_TABLE_CANT_HANDLE_BLOB     S1000          42000
1164           ER_TABLE_CANT_HANDLE_AUTO_INCREMENTS1000          42000
1166           ER_WRONG_COLUMN_NAME          S1000          42000
1167           ER_WRONG_KEY_COLUMN           S1000          42000
1169           ER_DUP_UNIQUE                 S1000          23000
1170           ER_BLOB_KEY_WITHOUT_LENGTH    S1000          42000
1171           ER_PRIMARY_CANT_HAVE_NULL     S1000          42000
1172           ER_TOO_MANY_ROWS              S1000          42000
1173           ER_REQUIRES_PRIMARY_KEY       S1000          42000
1177           ER_CHECK_NO_SUCH_TABLE        S1000          42000
1178           ER_CHECK_NOT_IMPLEMENTED      S1000          42000
1179           ER_CANT_DO_THIS_DURING_AN_TRANSACTIONS1000          25000
1184           ER_NEW_ABORTING_CONNECTION    S1000          08S01
1189           ER_MASTER_NET_READ            S1000          08S01
1190           ER_MASTER_NET_WRITE           S1000          08S01
1203           ER_TOO_MANY_USER_CONNECTIONS  S1000          42000
1205           ER_LOCK_WAIT_TIMEOUT          41000          41000
1207           ER_READ_ONLY_TRANSACTION      S1000          25000
1211           ER_NO_PERMISSION_TO_CREATE_USERS1000          42000
1213           ER_LOCK_DEADLOCK              41000          40001
1216           ER_NO_REFERENCED_ROW          S1000          23000
1217           ER_ROW_IS_REFERENCED          S1000          23000
1218           ER_CONNECT_TO_MASTER          S1000          08S01
1222           ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECTS1000          21000
1226           ER_USER_LIMIT_REACHED         S1000          42000
1230           ER_NO_DEFAULT                 S1000          42000
1231           ER_WRONG_VALUE_FOR_VAR        S1000          42000
1232           ER_WRONG_TYPE_FOR_VAR         S1000          42000
1234           ER_CANT_USE_OPTION_HERE       S1000          42000
1235           ER_NOT_SUPPORTED_YET          S1000          42000
1239           ER_WRONG_FK_DEF               S1000          42000
1241           ER_OPERAND_COLUMNS            S1000          21000
1242           ER_SUBQUERY_NO_1_ROW          S1000          21000
1247           ER_ILLEGAL_REFERENCE          S1000          42S22
1248           ER_DERIVED_MUST_HAVE_ALIAS    S1000          42000
1249           ER_SELECT_REDUCED             S1000          01000
1250           ER_TABLENAME_NOT_ALLOWED_HERE S1000          42000
1251           ER_NOT_SUPPORTED_AUTH_MODE    S1000          08004
1252           ER_SPATIAL_CANT_HAVE_NULL     S1000          42000
1253           ER_COLLATION_CHARSET_MISMATCH S1000          42000
1261           ER_WARN_TOO_FEW_RECORDS       S1000          01000
1262           ER_WARN_TOO_MANY_RECORDS      S1000          01000
1263           ER_WARN_NULL_TO_NOTNULL       S1000          01000
1264           ER_WARN_DATA_OUT_OF_RANGE     S1000          01000
1265           ER_WARN_DATA_TRUNCATED        S1000          01000
1280           ER_WRONG_NAME_FOR_INDEX       S1000          42000
1281           ER_WRONG_NAME_FOR_CATALOG     S1000          42000
1286           ER_UNKNOWN_STORAGE_ENGINE     S1000          42000


File: manual.info,  Node: connector-j-usagenotes,  Next: connector-j-support,  Prev: connector-j-reference,  Up: connector-j

20.4.5 Connector/J Notes and Tips
---------------------------------

* Menu:

* connector-j-usagenotes-basic::  Basic JDBC Concepts
* connector-j-usagenotes-j2ee::  Using Connector/J with J2EE and Other Java Frameworks
* connector-j-usagenotes-troubleshooting::  Common Problems and Solutions


File: manual.info,  Node: connector-j-usagenotes-basic,  Next: connector-j-usagenotes-j2ee,  Prev: connector-j-usagenotes,  Up: connector-j-usagenotes

20.4.5.1 Basic JDBC Concepts
............................

* Menu:

* connector-j-usagenotes-connect-drivermanager::  Connecting to MySQL Using the `DriverManager' Interface
* connector-j-usagenotes-statements::  Using Statements to Execute SQL
* connector-j-usagenotes-statements-callable::  Using `CallableStatements' to Execute Stored Procedures
* connector-j-usagenotes-last-insert-id::  Retrieving `AUTO_INCREMENT' Column Values

This section provides some general JDBC background.


File: manual.info,  Node: connector-j-usagenotes-connect-drivermanager,  Next: connector-j-usagenotes-statements,  Prev: connector-j-usagenotes-basic,  Up: connector-j-usagenotes-basic

20.4.5.2 Connecting to MySQL Using the `DriverManager' Interface
................................................................

When you are using JDBC outside of an application server, the
`DriverManager' class manages the establishment of Connections.

The `DriverManager' needs to be told which JDBC drivers it should try
to make Connections with. The easiest way to do this is to use
`Class.forName()' on the class that implements the `java.sql.Driver'
interface.  With MySQL Connector/J, the name of this class is
`com.mysql.jdbc.Driver'. With this method, you could use an external
configuration file to supply the driver class name and driver
parameters to use when connecting to a database.

The following section of Java code shows how you might register MySQL
Connector/J from the `main()' method of your application:

     import java.sql.Connection;
     import java.sql.DriverManager;
     import java.sql.SQLException;

     // Notice, do not import com.mysql.jdbc.*
     // or you will have problems!

     public class LoadDriver {
         public static void main(String[] args) {
             try {
                 // The newInstance() call is a work around for some
                 // broken Java implementations

                 Class.forName("com.mysql.jdbc.Driver").newInstance();
             } catch (Exception ex) {
                 // handle the error
             }
         }
     }

After the driver has been registered with the `DriverManager', you can
obtain a `Connection' instance that is connected to a particular
database by calling `DriverManager.getConnection()':

This example shows how you can obtain a `Connection' instance from the
`DriverManager'. There are a few different signatures for the
`getConnection()' method. You should see the API documentation that
comes with your JDK for more specific information on how to use them.

     import java.sql.Connection;
     import java.sql.DriverManager;
     import java.sql.SQLException;

     Connection conn = null;
     ...
     try {
         conn =
            DriverManager.getConnection("jdbc:mysql://localhost/test?" +
                                        "user=monty&password=greatsqldb");

         // Do something with the Connection

        ...
     } catch (SQLException ex) {
         // handle any errors
         System.out.println("SQLException: " + ex.getMessage());
         System.out.println("SQLState: " + ex.getSQLState());
         System.out.println("VendorError: " + ex.getErrorCode());
     }

Once a Connection is established, it can be used to create Statement and
PreparedStatement objects, as well as retrieve metadata about the
database. This is explained in the following sections.


File: manual.info,  Node: connector-j-usagenotes-statements,  Next: connector-j-usagenotes-statements-callable,  Prev: connector-j-usagenotes-connect-drivermanager,  Up: connector-j-usagenotes-basic

20.4.5.3 Using Statements to Execute SQL
........................................

Statement objects allow you to execute basic SQL queries and retrieve
the results through the `ResultSet' class which is described later.

To create a Statement instance, you call the `createStatement()' method
on the `Connection' object you have retrieved via one of the
`DriverManager.getConnection()' or `DataSource.getConnection()' methods
described earlier.

Once you have a Statement instance, you can execute a *Note `SELECT':
select. query by calling the `executeQuery(String)' method with the SQL
you want to use.

To update data in the database, use the `executeUpdate(String SQL)'
method. This method returns the number of rows affected by the update
statement.

If you do not know ahead of time whether the SQL statement will be a
*Note `SELECT': select. or an *Note `UPDATE': update./*Note `INSERT':
insert, then you can use the `execute(String SQL)' method. This method
will return true if the SQL query was a *Note `SELECT': select, or
false if it was an *Note `UPDATE': update, *Note `INSERT': insert, or
*Note `DELETE': delete. statement. If the statement was a *Note
`SELECT': select. query, you can retrieve the results by calling the
`getResultSet()' method. If the statement was an *Note `UPDATE': update,
*Note `INSERT': insert, or *Note `DELETE': delete. statement, you can
retrieve the affected rows count by calling `getUpdateCount()' on the
Statement instance.


     import java.sql.Connection;
     import java.sql.DriverManager;
     import java.sql.SQLException;
     import java.sql.Statement;
     import java.sql.ResultSet;

     // assume that conn is an already created JDBC connection (see previous examples)

     Statement stmt = null;
     ResultSet rs = null;

     try {
         stmt = conn.createStatement();
         rs = stmt.executeQuery("SELECT foo FROM bar");

         // or alternatively, if you don't know ahead of time that
         // the query will be a SELECT...

         if (stmt.execute("SELECT foo FROM bar")) {
             rs = stmt.getResultSet();
         }

         // Now do something with the ResultSet ....
     }
     catch (SQLException ex){
         // handle any errors
         System.out.println("SQLException: " + ex.getMessage());
         System.out.println("SQLState: " + ex.getSQLState());
         System.out.println("VendorError: " + ex.getErrorCode());
     }
     finally {
         // it is a good idea to release
         // resources in a finally{} block
         // in reverse-order of their creation
         // if they are no-longer needed

         if (rs != null) {
             try {
                 rs.close();
             } catch (SQLException sqlEx) { } // ignore

             rs = null;
         }

         if (stmt != null) {
             try {
                 stmt.close();
             } catch (SQLException sqlEx) { } // ignore

             stmt = null;
         }
     }


File: manual.info,  Node: connector-j-usagenotes-statements-callable,  Next: connector-j-usagenotes-last-insert-id,  Prev: connector-j-usagenotes-statements,  Up: connector-j-usagenotes-basic

20.4.5.4 Using `CallableStatements' to Execute Stored Procedures
................................................................

Starting with MySQL server version 5.0 when used with Connector/J 3.1.1
or newer, the java.sql.CallableStatement interface is fully implemented
with the exception of the `getParameterMetaData()' method.

For more information on MySQL stored procedures, please refer to
`http://dev.mysql.com/doc/mysql/en/stored-routines.html'.

Connector/J exposes stored procedure functionality through JDBC's
CallableStatement interface.

*Note*:

Current versions of MySQL server do not return enough information for
the JDBC driver to provide result set metadata for callable statements.
This means that when using `CallableStatement', `ResultSetMetaData' may
return `NULL'.

The following example shows a stored procedure that returns the value
of inOutParam incremented by 1, and the string passed in via inputParam
as a ResultSet:

     CREATE PROCEDURE demoSp(IN inputParam VARCHAR(255), \
                                             INOUT inOutParam INT)
     BEGIN
         DECLARE z INT;
         SET z = inOutParam + 1;
         SET inOutParam = z;

         SELECT inputParam;

         SELECT CONCAT('zyxw', inputParam);
     END

To use the `demoSp' procedure with Connector/J, follow these steps:

  1. Prepare the callable statement by using `Connection.prepareCall()'
     .

     Notice that you have to use JDBC escape syntax, and that the
     parentheses surrounding the parameter placeholders are not
     optional:

          import java.sql.CallableStatement;

          ...

              //
              // Prepare a call to the stored procedure 'demoSp'
              // with two parameters
              //
              // Notice the use of JDBC-escape syntax ({call ...})
              //

              CallableStatement cStmt = conn.prepareCall("{call demoSp(?, ?)}");

              cStmt.setString(1, "abcdefg");

     *Note*:

     `Connection.prepareCall()' is an expensive method, due to the
     metadata retrieval that the driver performs to support output
     parameters. For performance reasons, you should try to minimize
     unnecessary calls to `Connection.prepareCall()' by reusing
     CallableStatement instances in your code.

  2. Register the output parameters (if any exist)

     To retrieve the values of output parameters (parameters specified
     as `OUT' or `INOUT' when you created the stored procedure), JDBC
     requires that they be specified before statement execution using
     the various `registerOutputParameter()' methods in the
     CallableStatement interface:

          import java.sql.Types;
          ...
          //
          // Connector/J supports both named and indexed
          // output parameters. You can register output
          // parameters using either method, as well
          // as retrieve output parameters using either
          // method, regardless of what method was
          // used to register them.
          //
          // The following examples show how to use
          // the various methods of registering
          // output parameters (you should of course
          // use only one registration per parameter).
          //

          //
          // Registers the second parameter as output, and
          // uses the type 'INTEGER' for values returned from
          // getObject()
          //

          cStmt.registerOutParameter(2, Types.INTEGER);

          //
          // Registers the named parameter 'inOutParam', and
          // uses the type 'INTEGER' for values returned from
          // getObject()
          //

          cStmt.registerOutParameter("inOutParam", Types.INTEGER);
          ...

  3. Set the input parameters (if any exist)

     Input and in/out parameters are set as for PreparedStatement
     objects. However, CallableStatement also supports setting
     parameters by name:

          ...

              //
              // Set a parameter by index
              //

              cStmt.setString(1, "abcdefg");

              //
              // Alternatively, set a parameter using
              // the parameter name
              //

              cStmt.setString("inputParameter", "abcdefg");

              //
              // Set the 'in/out' parameter using an index
              //

              cStmt.setInt(2, 1);

              //
              // Alternatively, set the 'in/out' parameter
              // by name
              //

              cStmt.setInt("inOutParam", 1);

          ...

  4. Execute the CallableStatement, and retrieve any result sets or
     output parameters.

     Although CallableStatement supports calling any of the Statement
     execute methods (`executeUpdate()', `executeQuery()' or
     `execute()'), the most flexible method to call is `execute()', as
     you do not need to know ahead of time if the stored procedure
     returns result sets:

          ...

              boolean hadResults = cStmt.execute();

              //
              // Process all returned result sets
              //

              while (hadResults) {
                  ResultSet rs = cStmt.getResultSet();

                  // process result set
                  ...

                  hadResults = cStmt.getMoreResults();
              }

              //
              // Retrieve output parameters
              //
              // Connector/J supports both index-based and
              // name-based retrieval
              //

              int outputValue = cStmt.getInt(2); // index-based

              outputValue = cStmt.getInt("inOutParam"); // name-based

          ...


File: manual.info,  Node: connector-j-usagenotes-last-insert-id,  Prev: connector-j-usagenotes-statements-callable,  Up: connector-j-usagenotes-basic

20.4.5.5 Retrieving `AUTO_INCREMENT' Column Values
..................................................

Before version 3.0 of the JDBC API, there was no standard way of
retrieving key values from databases that supported auto increment or
identity columns. With older JDBC drivers for MySQL, you could always
use a MySQL-specific method on the Statement interface, or issue the
query `SELECT LAST_INSERT_ID()' after issuing an *Note `INSERT':
insert. to a table that had an `AUTO_INCREMENT' key. Using the
MySQL-specific method call isn't portable, and issuing a *Note
`SELECT': select. to get the `AUTO_INCREMENT' key's value requires
another round-trip to the database, which isn't as efficient as
possible. The following code snippets demonstrate the three different
ways to retrieve `AUTO_INCREMENT' values. First, we demonstrate the use
of the new JDBC-3.0 method `getGeneratedKeys()' which is now the
preferred method to use if you need to retrieve `AUTO_INCREMENT' keys
and have access to JDBC-3.0. The second example shows how you can
retrieve the same value using a standard `SELECT LAST_INSERT_ID()'
query. The final example shows how updatable result sets can retrieve
the `AUTO_INCREMENT' value when using the `insertRow()' method.

        Statement stmt = null;
        ResultSet rs = null;

        try {

         //
         // Create a Statement instance that we can use for
         // 'normal' result sets assuming you have a
         // Connection 'conn' to a MySQL database already
         // available

         stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
                                     java.sql.ResultSet.CONCUR_UPDATABLE);

         //
         // Issue the DDL queries for the table for this example
         //

         stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
         stmt.executeUpdate(
                 "CREATE TABLE autoIncTutorial ("
                 + "priKey INT NOT NULL AUTO_INCREMENT, "
                 + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

         //
         // Insert one row that will generate an AUTO INCREMENT
         // key in the 'priKey' field
         //

         stmt.executeUpdate(
                 "INSERT INTO autoIncTutorial (dataField) "
                 + "values ('Can I Get the Auto Increment Field?')",
                 Statement.RETURN_GENERATED_KEYS);

         //
         // Example of using Statement.getGeneratedKeys()
         // to retrieve the value of an auto-increment
         // value
         //

         int autoIncKeyFromApi = -1;

         rs = stmt.getGeneratedKeys();

         if (rs.next()) {
             autoIncKeyFromApi = rs.getInt(1);
         } else {

             // throw an exception from here
         }

         rs.close();

         rs = null;

         System.out.println("Key returned from getGeneratedKeys():"
             + autoIncKeyFromApi);
     } finally {

         if (rs != null) {
             try {
                 rs.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }

         if (stmt != null) {
             try {
                 stmt.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }
     }

        Statement stmt = null;
        ResultSet rs = null;

        try {

         //
         // Create a Statement instance that we can use for
         // 'normal' result sets.

         stmt = conn.createStatement();

         //
         // Issue the DDL queries for the table for this example
         //

         stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
         stmt.executeUpdate(
                 "CREATE TABLE autoIncTutorial ("
                 + "priKey INT NOT NULL AUTO_INCREMENT, "
                 + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

         //
         // Insert one row that will generate an AUTO INCREMENT
         // key in the 'priKey' field
         //

         stmt.executeUpdate(
                 "INSERT INTO autoIncTutorial (dataField) "
                 + "values ('Can I Get the Auto Increment Field?')");

         //
         // Use the MySQL LAST_INSERT_ID()
         // function to do the same thing as getGeneratedKeys()
         //

         int autoIncKeyFromFunc = -1;
         rs = stmt.executeQuery("SELECT LAST_INSERT_ID()");

         if (rs.next()) {
             autoIncKeyFromFunc = rs.getInt(1);
         } else {
             // throw an exception from here
         }

         rs.close();

         System.out.println("Key returned from " +
                            "'SELECT LAST_INSERT_ID()': " +
                            autoIncKeyFromFunc);

     } finally {

         if (rs != null) {
             try {
                 rs.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }

         if (stmt != null) {
             try {
                 stmt.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }
     }

        Statement stmt = null;
        ResultSet rs = null;

        try {

         //
         // Create a Statement instance that we can use for
         // 'normal' result sets as well as an 'updatable'
         // one, assuming you have a Connection 'conn' to
         // a MySQL database already available
         //

         stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
                                     java.sql.ResultSet.CONCUR_UPDATABLE);

         //
         // Issue the DDL queries for the table for this example
         //

         stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
         stmt.executeUpdate(
                 "CREATE TABLE autoIncTutorial ("
                 + "priKey INT NOT NULL AUTO_INCREMENT, "
                 + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

         //
         // Example of retrieving an AUTO INCREMENT key
         // from an updatable result set
         //

         rs = stmt.executeQuery("SELECT priKey, dataField "
            + "FROM autoIncTutorial");

         rs.moveToInsertRow();

         rs.updateString("dataField", "AUTO INCREMENT here?");
         rs.insertRow();

         //
         // the driver adds rows at the end
         //

         rs.last();

         //
         // We should now be on the row we just inserted
         //

         int autoIncKeyFromRS = rs.getInt("priKey");

         rs.close();

         rs = null;

         System.out.println("Key returned for inserted row: "
             + autoIncKeyFromRS);

     } finally {

         if (rs != null) {
             try {
                 rs.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }

         if (stmt != null) {
             try {
                 stmt.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }
     }

When you run the preceding example code, you should get the following
output: Key returned from `getGeneratedKeys()': 1 Key returned from
`SELECT LAST_INSERT_ID()': 1 Key returned for inserted row: 2 You
should be aware, that at times, it can be tricky to use the `SELECT
LAST_INSERT_ID()' query, as that function's value is scoped to a
connection. So, if some other query happens on the same connection, the
value will be overwritten. On the other hand, the `getGeneratedKeys()'
method is scoped by the Statement instance, so it can be used even if
other queries happen on the same connection, but not on the same
Statement instance.


File: manual.info,  Node: connector-j-usagenotes-j2ee,  Next: connector-j-usagenotes-troubleshooting,  Prev: connector-j-usagenotes-basic,  Up: connector-j-usagenotes

20.4.5.6 Using Connector/J with J2EE and Other Java Frameworks
..............................................................

* Menu:

* connector-j-usagenotes-j2ee-concepts::  General J2EE Concepts
* connector-j-usagenotes-tomcat::  Using Connector/J with Tomcat
* connector-j-usagenotes-jboss::  Using Connector/J with JBoss
* connector-j-usagenotes-spring-config::  Using Connector/J with Spring
* connector-j-usagenotes-glassfish-config::  Using Connector/J with GlassFish

This section describes how to use Connector/J in several contexts.


File: manual.info,  Node: connector-j-usagenotes-j2ee-concepts,  Next: connector-j-usagenotes-tomcat,  Prev: connector-j-usagenotes-j2ee,  Up: connector-j-usagenotes-j2ee

20.4.5.7 General J2EE Concepts
..............................

* Menu:

* connector-j-usagenotes-j2ee-concepts-connection-pooling::  Understanding Connection Pooling

This section provides general background on J2EE concepts that pertain
to use of Connector/J.


File: manual.info,  Node: connector-j-usagenotes-j2ee-concepts-connection-pooling,  Prev: connector-j-usagenotes-j2ee-concepts,  Up: connector-j-usagenotes-j2ee-concepts

20.4.5.8 Understanding Connection Pooling
.........................................

Connection pooling is a technique of creating and managing a pool of
connections that are ready for use by any thread that needs them.

This technique of pooling connections is based on the fact that most
applications only need a thread to have access to a JDBC connection
when they are actively processing a transaction, which usually take
only milliseconds to complete. When not processing a transaction, the
connection would otherwise sit idle. Instead, connection pooling allows
the idle connection to be used by some other thread to do useful work.

In practice, when a thread needs to do work against a MySQL or other
database with JDBC, it requests a connection from the pool. When the
thread is finished using the connection, it returns it to the pool, so
that it may be used by any other threads that want to use it.

When the connection is loaned out from the pool, it is used exclusively
by the thread that requested it. From a programming point of view, it
is the same as if your thread called `DriverManager.getConnection()'
every time it needed a JDBC connection, however with connection
pooling, your thread may end up using either a new, or already-existing
connection.

Connection pooling can greatly increase the performance of your Java
application, while reducing overall resource usage. The main benefits
to connection pooling are:

   * Reduced connection creation time

     Although this is not usually an issue with the quick connection
     setup that MySQL offers compared to other databases, creating new
     JDBC connections still incurs networking and JDBC driver overhead
     that will be avoided if connections are recycled.

   * Simplified programming model

     When using connection pooling, each individual thread can act as
     though it has created its own JDBC connection, allowing you to use
     straight-forward JDBC programming techniques.

   * Controlled resource usage

     If you do not use connection pooling, and instead create a new
     connection every time a thread needs one, your application's
     resource usage can be quite wasteful and lead to unpredictable
     behavior under load.

Remember that each connection to MySQL has overhead (memory, CPU,
context switches, and so forth) on both the client and server side.
Every connection limits how many resources there are available to your
application as well as the MySQL server. Many of these resources will
be used whether or not the connection is actually doing any useful work!

Connection pools can be tuned to maximize performance, while keeping
resource utilization below the point where your application will start
to fail rather than just run slower.

Luckily, Sun has standardized the concept of connection pooling in JDBC
through the JDBC-2.0 Optional interfaces, and all major application
servers have implementations of these APIs that work fine with MySQL
Connector/J.

Generally, you configure a connection pool in your application server
configuration files, and access it via the Java Naming and Directory
Interface (JNDI). The following code shows how you might use a
connection pool from an application deployed in a J2EE application
server:

     import java.sql.Connection;
     import java.sql.SQLException;
     import java.sql.Statement;

     import javax.naming.InitialContext;
     import javax.sql.DataSource;

     public class MyServletJspOrEjb {

         public void doSomething() throws Exception {
             /*
              * Create a JNDI Initial context to be able to
              *  lookup  the DataSource
              *
              * In production-level code, this should be cached as
              * an instance or static variable, as it can
              * be quite expensive to create a JNDI context.
              *
              * Note: This code only works when you are using servlets
              * or EJBs in a J2EE application server. If you are
              * using connection pooling in standalone Java code, you
              * will have to create/configure datasources using whatever
              * mechanisms your particular connection pooling library
              * provides.
              */

             InitialContext ctx = new InitialContext();

              /*
               * Lookup the DataSource, which will be backed by a pool
               * that the application server provides. DataSource instances
               * are also a good candidate for caching as an instance
               * variable, as JNDI lookups can be expensive as well.
               */

             DataSource ds =
               (DataSource)ctx.lookup("java:comp/env/jdbc/MySQLDB");

             /*
              * The following code is what would actually be in your
              * Servlet, JSP or EJB 'service' method...where you need
              * to work with a JDBC connection.
              */

             Connection conn = null;
             Statement stmt = null;

             try {
                 conn = ds.getConnection();

                 /*
                  * Now, use normal JDBC programming to work with
                  * MySQL, making sure to close each resource when you're
                  * finished with it, which allows the connection pool
                  * resources to be recovered as quickly as possible
                  */

                 stmt = conn.createStatement();
                 stmt.execute("SOME SQL QUERY");

                 stmt.close();
                 stmt = null;

                 conn.close();
                 conn = null;
             } finally {
                 /*
                  * close any jdbc instances here that weren't
                  * explicitly closed during normal code path, so
                  * that we don't 'leak' resources...
                  */

                 if (stmt != null) {
                     try {
                         stmt.close();
                     } catch (sqlexception sqlex) {
                         // ignore -- as we can't do anything about it here
                     }

                     stmt = null;
                 }

                 if (conn != null) {
                     try {
                         conn.close();
                     } catch (sqlexception sqlex) {
                         // ignore -- as we can't do anything about it here
                     }

                     conn = null;
                 }
             }
         }
     }

As shown in the example above, after obtaining the JNDI InitialContext,
and looking up the DataSource, the rest of the code should look
familiar to anyone who has done JDBC programming in the past.

The most important thing to remember when using connection pooling is
to make sure that no matter what happens in your code (exceptions,
flow-of-control, and so forth), connections, and anything created by
them (such as statements or result sets) are closed, so that they may be
re-used, otherwise they will be stranded, which in the best case means
that the MySQL server resources they represent (such as buffers, locks,
or sockets) may be tied up for some time, or worst case, may be tied up
forever.

What Is the Best Size for my Connection Pool?

As with all other configuration rules-of-thumb, the answer is: it
depends. Although the optimal size depends on anticipated load and
average database transaction time, the optimum connection pool size is
smaller than you might expect. If you take Sun's Java Petstore blueprint
application for example, a connection pool of 15-20 connections can
serve a relatively moderate load (600 concurrent users) using MySQL and
Tomcat with response times that are acceptable.

To correctly size a connection pool for your application, you should
create load test scripts with tools such as Apache JMeter or The
Grinder, and load test your application.

An easy way to determine a starting point is to configure your
connection pool's maximum number of connections to be unbounded, run a
load test, and measure the largest amount of concurrently used
connections. You can then work backward from there to determine what
values of minimum and maximum pooled connections give the best
performance for your particular application.


File: manual.info,  Node: connector-j-usagenotes-tomcat,  Next: connector-j-usagenotes-jboss,  Prev: connector-j-usagenotes-j2ee-concepts,  Up: connector-j-usagenotes-j2ee

20.4.5.9 Using Connector/J with Tomcat
......................................

The following instructions are based on the instructions for
Tomcat-5.x, available at
`http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.html'
which is current at the time this document was written.

First, install the .jar file that comes with Connector/J in
`$CATALINA_HOME/common/lib' so that it is available to all applications
installed in the container.

Next, Configure the JNDI DataSource by adding a declaration resource to
`$CATALINA_HOME/conf/server.xml' in the context that defines your web
application:

     <Context ....>

       ...

       <Resource name="jdbc/MySQLDB"
                    auth="Container"
                    type="javax.sql.DataSource"/>

       <!-- The name you used above, must match _exactly_ here!

            The connection pool will be bound into JNDI with the name
            "java:/comp/env/jdbc/MySQLDB"
       -->

       <ResourceParams name="jdbc/MySQLDB">
         <parameter>
           <name>factory</name>
           <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
         </parameter>

         <!-- Don't set this any higher than max_connections on your
              MySQL server, usually this should be a 10 or a few 10's
              of connections, not hundreds or thousands -->

         <parameter>
           <name>maxActive</name>
           <value>10</value>
         </parameter>

         <!-- You don't want to many idle connections hanging around
              if you can avoid it, only enough to soak up a spike in
              the load -->

         <parameter>
           <name>maxIdle</name>
           <value>5</value>
         </parameter>

         <!-- Don't use autoReconnect=true, it's going away eventually
              and it's a crutch for older connection pools that couldn't
              test connections. You need to decide whether your application
              is supposed to deal with SQLExceptions (hint, it should), and
              how much of a performance penalty you're willing to pay
              to ensure 'freshness' of the connection -->

         <parameter>
           <name>validationQuery</name>
           <value>SELECT 1</value>
         </parameter>

        <!-- The most conservative approach is to test connections
             before they're given to your application. For most applications
             this is okay, the query used above is very small and takes
             no real server resources to process, other than the time used
             to traverse the network.

             If you have a high-load application you'll need to rely on
             something else. -->

         <parameter>
           <name>testOnBorrow</name>
           <value>true</value>
         </parameter>

        <!-- Otherwise, or in addition to testOnBorrow, you can test
             while connections are sitting idle -->

         <parameter>
           <name>testWhileIdle</name>
           <value>true</value>
         </parameter>

         <!-- You have to set this value, otherwise even though
              you've asked connections to be tested while idle,
              the idle evicter thread will never run -->

         <parameter>
           <name>timeBetweenEvictionRunsMillis</name>
           <value>10000</value>
         </parameter>

         <!-- Don't allow connections to hang out idle too long,
              never longer than what wait_timeout is set to on the
              server...A few minutes or even fraction of a minute
              is sometimes okay here, it depends on your application
              and how much spikey load it will see -->

         <parameter>
           <name>minEvictableIdleTimeMillis</name>
           <value>60000</value>
         </parameter>

         <!-- Username and password used when connecting to MySQL -->

         <parameter>
          <name>username</name>
          <value>someuser</value>
         </parameter>

         <parameter>
          <name>password</name>
          <value>somepass</value>
         </parameter>

         <!-- Class name for the Connector/J driver -->

         <parameter>
            <name>driverClassName</name>
            <value>com.mysql.jdbc.Driver</value>
         </parameter>

         <!-- The JDBC connection url for connecting to MySQL, notice
              that if you want to pass any other MySQL-specific parameters
              you should pass them here in the URL, setting them using the
              parameter tags above will have no effect, you will also
              need to use &amp; to separate parameter values as the
              ampersand is a reserved character in XML -->

         <parameter>
           <name>url</name>
           <value>jdbc:mysql://localhost:3306/test</value>
         </parameter>

       </ResourceParams>
     </Context>

In general, you should follow the installation instructions that come
with your version of Tomcat, as the way you configure datasources in
Tomcat changes from time-to-time, and unfortunately if you use the
wrong syntax in your XML file, you will most likely end up with an
exception similar to the following:

     Error: java.sql.SQLException: Cannot load JDBC driver class 'null ' SQL
     state: null


File: manual.info,  Node: connector-j-usagenotes-jboss,  Next: connector-j-usagenotes-spring-config,  Prev: connector-j-usagenotes-tomcat,  Up: connector-j-usagenotes-j2ee

20.4.5.10 Using Connector/J with JBoss
......................................

These instructions cover JBoss-4.x. To make the JDBC driver classes
available to the application server, copy the .jar file that comes with
Connector/J to the `lib' directory for your server configuration (which
is usually called `default'). Then, in the same configuration
directory, in the subdirectory named deploy, create a datasource
configuration file that ends with "-ds.xml", which tells JBoss to
deploy this file as a JDBC Datasource. The file should have the
following contents:

     <datasources>
         <local-tx-datasource>
             <!-- This connection pool will be bound into JNDI with the name
                  "java:/MySQLDB" -->

             <jndi-name>MySQLDB</jndi-name>
             <connection-url>jdbc:mysql://localhost:3306/dbname</connection-url>
             <driver-class>com.mysql.jdbc.Driver</driver-class>
             <user-name>user</user-name>
             <password>pass</password>

             <min-pool-size>5</min-pool-size>

             <!-- Don't set this any higher than max_connections on your
              MySQL server, usually this should be a 10 or a few 10's
              of connections, not hundreds or thousands -->

             <max-pool-size>20</max-pool-size>

             <!-- Don't allow connections to hang out idle too long,
              never longer than what wait_timeout is set to on the
              server...A few minutes is usually okay here,
              it depends on your application
              and how much spikey load it will see -->

             <idle-timeout-minutes>5</idle-timeout-minutes>

             <!-- If you're using Connector/J 3.1.8 or newer, you can use
                  our implementation of these to increase the robustness
                  of the connection pool. -->

             <exception-sorter-class-name>
       com.mysql.jdbc.integration.jboss.ExtendedMysqlExceptionSorter
             </exception-sorter-class-name>
             <valid-connection-checker-class-name>
       com.mysql.jdbc.integration.jboss.MysqlValidConnectionChecker
             </valid-connection-checker-class-name>

         </local-tx-datasource>
     </datasources>


File: manual.info,  Node: connector-j-usagenotes-spring-config,  Next: connector-j-usagenotes-glassfish-config,  Prev: connector-j-usagenotes-jboss,  Up: connector-j-usagenotes-j2ee

20.4.5.11 Using Connector/J with Spring
.......................................

* Menu:

* connector-j-usagenotes-spring-config-jdbctemplate::  Using JdbcTemplate
* connector-j-usagenotes-spring-config-transactional::  Transactional JDBC Access
* connector-j-usagenotes-spring-config-connpooling::  Connection Pooling

The Spring Framework is a Java-based application framework designed for
assisting in application design by providing a way to configure
components. The technique used by Spring is a well known design pattern
called Dependency Injection (see Inversion of Control Containers and
the Dependency Injection pattern
(http://www.martinfowler.com/articles/injection.html)). This article
will focus on Java-oriented access to MySQL databases with Spring 2.0.
For those wondering, there is a .NET port of Spring appropriately named
Spring.NET.

Spring is not only a system for configuring components, but also
includes support for aspect oriented programming (AOP).  This is one of
the main benefits and the foundation for Spring's resource and
transaction management. Spring also provides utilities for integrating
resource management with JDBC and Hibernate.

For the examples in this section the MySQL world sample database will
be used. The first task is to set up a MySQL data source through
Spring. Components within Spring use the "bean" terminology. For
example, to configure a connection to a MySQL server supporting the
world sample database you might use:

     <util:map id="dbProps">
         <entry key="db.driver" value="com.mysql.jdbc.Driver"/>
         <entry key="db.jdbcurl" value="jdbc:mysql://localhost/world"/>
         <entry key="db.username" value="myuser"/>
         <entry key="db.password" value="mypass"/>
     </util:map>

In the above example we are assigning values to properties that will be
used in the configuration. For the datasource configuration:

     <bean id="dataSource"
            class="org.springframework.jdbc.datasource.DriverManagerDataSource">
         <property name="driverClassName" value="${db.driver}"/>
         <property name="url" value="${db.jdbcurl}"/>
         <property name="username" value="${db.username}"/>
         <property name="password" value="${db.password}"/>
     </bean>

The placeholders are used to provide values for properties of this
bean. This means that you can specify all the properties of the
configuration in one place instead of entering the values for each
property on each bean. We do, however, need one more bean to pull this
all together. The last bean is responsible for actually replacing the
placeholders with the property values.

     <bean
      class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
         <property name="properties" ref="dbProps"/>
     </bean>

Now that we have our MySQL data source configured and ready to go, we
write some Java code to access it. The example below will retrieve
three random cities and their corresponding country using the data
source we configured with Spring.

     // Create a new application context. this processes the Spring config
     ApplicationContext ctx =
         new ClassPathXmlApplicationContext("ex1appContext.xml");
     // Retrieve the data source from the application context
         DataSource ds = (DataSource) ctx.getBean("dataSource");
     // Open a database connection using Spring's DataSourceUtils
     Connection c = DataSourceUtils.getConnection(ds);
     try {
         // retrieve a list of three random cities
         PreparedStatement ps = c.prepareStatement(
             "select City.Name as 'City', Country.Name as 'Country' " +
             "from City inner join Country on City.CountryCode = Country.Code " +
             "order by rand() limit 3");
         ResultSet rs = ps.executeQuery();
         while(rs.next()) {
             String city = rs.getString("City");
             String country = rs.getString("Country");
             System.out.printf("The city %s is in %s%n", city, country);
         }
     } catch (SQLException ex) {
         // something has failed and we print a stack trace to analyse the error
         ex.printStackTrace();
         // ignore failure closing connection
         try { c.close(); } catch (SQLException e) { }
     } finally {
         // properly release our connection
         DataSourceUtils.releaseConnection(c, ds);
     }

This is very similar to normal JDBC access to MySQL with the main
difference being that we are using DataSourceUtils instead of the
DriverManager to create the connection.

While it may seem like a small difference, the implications are
somewhat far reaching. Spring manages this resource in a way similar to
a container managed data source in a J2EE application server. When a
connection is opened, it can be subsequently accessed in other parts of
the code if it is synchronized with a transaction. This makes it
possible to treat different parts of your application as transactional
instead of passing around a database connection.


File: manual.info,  Node: connector-j-usagenotes-spring-config-jdbctemplate,  Next: connector-j-usagenotes-spring-config-transactional,  Prev: connector-j-usagenotes-spring-config,  Up: connector-j-usagenotes-spring-config

20.4.5.12 Using JdbcTemplate
............................

Spring makes extensive use of the Template method design pattern (see
Template Method Pattern
(http://en.wikipedia.org/wiki/Template_method_pattern)). Our immediate
focus will be on the `JdbcTemplate' and related classes, specifically
`NamedParameterJdbcTemplate'.  The template classes handle obtaining
and releasing a connection for data access when one is needed.

The next example shows how to use `NamedParameterJdbcTemplate' inside
of a DAO (Data Access Object) class to retrieve a random city given a
country code.

     public class Ex2JdbcDao {
          /**
          * Data source reference which will be provided by Spring.
          */
          private DataSource dataSource;

          /**
          * Our query to find a random city given a country code. Notice
          * the ":country" parameter towards the end. This is called a
          * named parameter.
          */
          private String queryString = "select Name from City " +
             "where CountryCode = :country order by rand() limit 1";

          /**
          * Retrieve a random city using Spring JDBC access classes.
          */
          public String getRandomCityByCountryCode(String cntryCode) {
              // A template that allows using queries with named parameters
              NamedParameterJdbcTemplate template =
              new NamedParameterJdbcTemplate(dataSource);
              // A java.util.Map is used to provide values for the parameters
              Map params = new HashMap();
              params.put("country", cntryCode);
              // We query for an Object and specify what class we are expecting
              return (String)template.queryForObject(queryString, params, String.class);
          }

         /**
         * A JavaBean setter-style method to allow Spring to inject the data source.
         * @param dataSource
         */
         public void setDataSource(DataSource dataSource) {
             this.dataSource = dataSource;
         }
     }

The focus in the above code is on the `getRandomCityByCountryCode()'
method. We pass a country code and use the `NamedParameterJdbcTemplate'
to query for a city. The country code is placed in a Map with the key
"country", which is the parameter is named in the SQL query.

To access this code, you need to configure it with Spring by providing
a reference to the data source.

     <bean id="dao" class="code.Ex2JdbcDao">
         <property name="dataSource" ref="dataSource"/>
     </bean>

At this point, we can just grab a reference to the DAO from Spring and
call `getRandomCityByCountryCode()'.

     // Create the application context
         ApplicationContext ctx =
         new ClassPathXmlApplicationContext("ex2appContext.xml");
         // Obtain a reference to our DAO
         Ex2JdbcDao dao = (Ex2JdbcDao) ctx.getBean("dao");

         String countryCode = "USA";

         // Find a few random cities in the US
         for(int i = 0; i < 4; ++i)
             System.out.printf("A random city in %s is %s%n", countryCode,
                 dao.getRandomCityByCountryCode(countryCode));

This example shows how to use Spring's JDBC classes to completely
abstract away the use of traditional JDBC classes including
`Connection' and `PreparedStatement'.


File: manual.info,  Node: connector-j-usagenotes-spring-config-transactional,  Next: connector-j-usagenotes-spring-config-connpooling,  Prev: connector-j-usagenotes-spring-config-jdbctemplate,  Up: connector-j-usagenotes-spring-config

20.4.5.13 Transactional JDBC Access
...................................

You might be wondering how we can add transactions into our code if we
do not deal directly with the JDBC classes.  Spring provides a
transaction management package that not only replaces JDBC transaction
management, but also allows declarative transaction management
(configuration instead of code).

In order to use transactional database access, we will need to change
the storage engine of the tables in the world database. The downloaded
script explicitly creates MyISAM tables which do not support
transactional semantics. The InnoDB storage engine does support
transactions and this is what we will be using. We can change the
storage engine with the following statements.

     ALTER TABLE City ENGINE=InnoDB;
     ALTER TABLE Country ENGINE=InnoDB;
     ALTER TABLE CountryLanguage ENGINE=InnoDB;

A good programming practice emphasized by Spring is separating
interfaces and implementations. What this means is that we can create a
Java interface and only use the operations on this interface without
any internal knowledge of what the actual implementation is. We will
let Spring manage the implementation and with this it will manage the
transactions for our implementation.

First you create a simple interface:

     public interface Ex3Dao {
         Integer createCity(String name, String countryCode,
         String district, Integer population);
     }

This interface contains one method that will create a new city record
in the database and return the id of the new record. Next you need to
create an implementation of this interface.

     public class Ex3DaoImpl implements Ex3Dao {
         protected DataSource dataSource;
         protected SqlUpdate updateQuery;
         protected SqlFunction idQuery;

         public Integer createCity(String name, String countryCode,
             String district, Integer population) {
                 updateQuery.update(new Object[] { name, countryCode,
                        district, population });
                 return getLastId();
             }

         protected Integer getLastId() {
             return idQuery.run();
         }
     }

You can see that we only operate on abstract query objects here and do
not deal directly with the JDBC API. Also, this is the complete
implementation. All of our transaction management will be dealt with in
the configuration. To get the configuration started, we need to create
the DAO.

     <bean id="dao" class="code.Ex3DaoImpl">
         <property name="dataSource" ref="dataSource"/>
         <property name="updateQuery">...</property>
         <property name="idQuery">...</property>
     </bean>

Now you need to set up the transaction configuration. The first thing
you must do is create transaction manager to manage the data source and
a specification of what transaction properties are required for for the
`dao' methods.

     <bean id="transactionManager"
       class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
         <property name="dataSource" ref="dataSource"/>
     </bean>

     <tx:advice id="txAdvice" transaction-manager="transactionManager">
         <tx:attributes>
             <tx:method name="*"/>
         </tx:attributes>
     </tx:advice>

The preceding code creates a transaction manager that handles
transactions for the data source provided to it. The `txAdvice' uses
this transaction manager and the attributes specify to create a
transaction for all methods. Finally you need to apply this advice with
an AOP pointcut.

     <aop:config>
         <aop:pointcut id="daoMethods"
             expression="execution(* code.Ex3Dao.*(..))"/>
          <aop:advisor advice-ref="txAdvice" pointcut-ref="daoMethods"/>
     </aop:config>

This basically says that all methods called on the `Ex3Dao' interface
will be wrapped in a transaction. To make use of this, you only have to
retrieve the `dao' from the application context and call a method on
the `dao' instance.

     Ex3Dao dao = (Ex3Dao) ctx.getBean("dao");
     Integer id = dao.createCity(name,  countryCode, district, pop);

We can verify from this that there is no transaction management
happening in our Java code and it is all configured with Spring. This
is a very powerful notion and regarded as one of the most beneficial
features of Spring.


File: manual.info,  Node: connector-j-usagenotes-spring-config-connpooling,  Prev: connector-j-usagenotes-spring-config-transactional,  Up: connector-j-usagenotes-spring-config

20.4.5.14 Connection Pooling
............................

In many sitations, such as web applications, there will be a large
number of small database transactions. When this is the case, it
usually makes sense to create a pool of database connections available
for web requests as needed.  Although MySQL does not spawn an extra
process when a connection is made, there is still a small amount of
overhead to create and set up the connection. Pooling of connections
also alleviates problems such as collecting large amounts of sockets in
the `TIME_WAIT' state.

Setting up pooling of MySQL connections with Spring is as simple as
changing the data source configuration in the application context.
There are a number of configurations that we can use. The first example
is based on the Jakarta Commons DBCP library
(http://jakarta.apache.org/commons/dbcp/). The example below replaces
the source configuration that was based on `DriverManagerDataSource'
with DBCP's BasicDataSource.

     <bean id="dataSource" destroy-method="close"
       class="org.apache.commons.dbcp.BasicDataSource">
         <property name="driverClassName" value="${db.driver}"/>
         <property name="url" value="${db.jdbcurl}"/>
         <property name="username" value="${db.username}"/>
         <property name="password" value="${db.password}"/>
         <property name="initialSize" value="3"/>
     </bean>

The configuration of the two solutions is very similar. The difference
is that DBCP will pool connections to the database instead of creating
a new connection every time one is requested. We have also set a
parameter here called `initialSize'. This tells DBCP that we want three
connections in the pool when it is created.

Another way to configure connection pooling is to configure a data
source in our J2EE application server. Using JBoss as an example, you
can set up the MySQL connection pool by creating a file called
`mysql-local-ds.xml' and placing it in the server/default/deploy
directory in JBoss. Once we have this setup, we can use JNDI to look it
up. With Spring, this lookup is very simple. The data source
configuration looks like this.

     <jee:jndi-lookup id="dataSource" jndi-name="java:MySQL_DS"/>


File: manual.info,  Node: connector-j-usagenotes-glassfish-config,  Prev: connector-j-usagenotes-spring-config,  Up: connector-j-usagenotes-j2ee

20.4.5.15 Using Connector/J with GlassFish
..........................................


File: manual.info,  Node: connector-j-usagenotes-troubleshooting,  Prev: connector-j-usagenotes-j2ee,  Up: connector-j-usagenotes

20.4.5.16 Common Problems and Solutions
.......................................

There are a few issues that seem to be commonly encountered often by
users of MySQL Connector/J. This section deals with their symptoms, and
their resolutions.

*Questions*
   * 20.4.5.3.1: When I try to connect to the database with MySQL
     Connector/J, I get the following exception:

          SQLException: Server configuration denies access to data source
          SQLState: 08001
          VendorError: 0

     What is going on? I can connect just fine with the MySQL
     command-line client.

   * 20.4.5.3.2: My application throws an SQLException 'No Suitable
     Driver'. Why is this happening?

   * 20.4.5.3.3: I'm trying to use MySQL Connector/J in an applet or
     application and I get an exception similar to:

          SQLException: Cannot connect to MySQL server on host:3306.
          Is there a MySQL server running on the machine/port you
          are trying to connect to?

          (java.security.AccessControlException)
          SQLState: 08S01
          VendorError: 0

   * 20.4.5.3.4: I have a servlet/application that works fine for a day,
     and then stops working overnight

   * 20.4.5.3.5: I'm trying to use JDBC-2.0 updatable result sets, and I
     get an exception saying my result set is not updatable.

   * 20.4.5.3.6: I cannot connect to the MySQL server using Connector/J,
     and I'm sure the connection paramters are correct.

   * 20.4.5.3.7: I am trying to connect to my MySQL server within my
     application, but I get the following error and stack trace:

          java.net.SocketException
          MESSAGE: Software caused connection abort: recv failed

          STACKTRACE:

          java.net.SocketException: Software caused connection abort: recv failed
          at java.net.SocketInputStream.socketRead0(Native Method)
          at java.net.SocketInputStream.read(Unknown Source)
          at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1392)
          at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:1414)
          at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:625)
          at com.mysql.jdbc.Connection.createNewIO(Connection.java:1926)
          at com.mysql.jdbc.Connection.<init>(Connection.java:452)
          at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:411)

   * 20.4.5.3.8: My application is deployed through JBoss and I am using
     transactions to handle the statements on the MySQL database. Under
     heavy loads I am getting a error and stack trace, but these only
     occur after a fixed period of heavy activity.

   * 20.4.5.3.9: When using `gcj' an `java.io.CharConversionException'
     is raised when working with certain character sequences.

   * 20.4.5.3.10: Updating a table that contains a primary key that is
     either *Note `FLOAT': numeric-types. or compound primary key that
     uses *Note `FLOAT': numeric-types.  fails to update the table and
     raises an exception.

   * 20.4.5.3.11: You get an `ER_NET_PACKET_TOO_LARGE' exception, even
     though the binary blob size you want to insert via JDBC is safely
     below the `max_allowed_packet' size.

*Questions and Answers* *20.4.5.3.1: ** When I try to connect to the
database with MySQL Connector/J, I get the following exception: *
     SQLException: Server configuration denies access to data source
     SQLState: 08001
     VendorError: 0
* What is going on? I can connect just fine with the MySQL command-line
client.  *

MySQL Connector/J must use TCP/IP sockets to connect to MySQL, as Java
does not support Unix Domain Sockets.  Therefore, when MySQL
Connector/J connects to MySQL, the security manager in MySQL server
will use its grant tables to determine whether the connection should be
allowed.

You must add the necessary security credentials to the MySQL server for
this to happen, using the *Note `GRANT': grant. statement to your MySQL
Server. See *Note grant::, for more information.

*Note*:

Testing your connectivity with the *Note `mysql': mysql. command-line
client will not work unless you add the `--host' flag, and use
something other than `localhost' for the host. The *Note `mysql':
mysql. command-line client will use Unix domain sockets if you use the
special host name `localhost'. If you are testing connectivity to
`localhost', use `127.0.0.1' as the host name instead.

*Warning*:

Changing privileges and permissions improperly in MySQL can potentially
cause your server installation to not have optimal security properties.

*20.4.5.3.2: ** My application throws an SQLException 'No Suitable
Driver'. Why is this happening?  *

There are three possible causes for this error:

   * The Connector/J driver is not in your `CLASSPATH', see *Note
     connector-j-installing::.

   * The format of your connection URL is incorrect, or you are
     referencing the wrong JDBC driver.

   * When using DriverManager, the `jdbc.drivers' system property has
     not been populated with the location of the Connector/J driver.

*20.4.5.3.3: ** I'm trying to use MySQL Connector/J in an applet or
application and I get an exception similar to: *
     SQLException: Cannot connect to MySQL server on host:3306.
     Is there a MySQL server running on the machine/port you
     are trying to connect to?

     (java.security.AccessControlException)
     SQLState: 08S01
     VendorError: 0

Either you're running an Applet, your MySQL server has been installed
with the "-skip-networking" option set, or your MySQL server has a
firewall sitting in front of it.

Applets can only make network connections back to the machine that runs
the web server that served the .class files for the applet. This means
that MySQL must run on the same machine (or you must have some sort of
port re-direction) for this to work. This also means that you will not
be able to test applets from your local file system, you must always
deploy them to a web server.

MySQL Connector/J can only communicate with MySQL using TCP/IP, as Java
does not support Unix domain sockets.  TCP/IP communication with MySQL
might be affected if MySQL was started with the "-skip-networking"
flag, or if it is firewalled.

If MySQL has been started with the "-skip-networking" option set (the
Debian Linux package of MySQL server does this for example), you need
to comment it out in the file /etc/mysql/my.cnf or /etc/my.cnf. Of
course your my.cnf file might also exist in the `data' directory of
your MySQL server, or anywhere else (depending on how MySQL was
compiled for your system).  Binaries created by us always look in
/etc/my.cnf and [datadir]/my.cnf. If your MySQL server has been
firewalled, you will need to have the firewall configured to allow
TCP/IP connections from the host where your Java code is running to the
MySQL server on the port that MySQL is listening to (by default, 3306).

*20.4.5.3.4: ** I have a servlet/application that works fine for a day,
and then stops working overnight *

MySQL closes connections after 8 hours of inactivity. You either need
to use a connection pool that handles stale connections or use the
"autoReconnect" parameter (see *Note
connector-j-reference-configuration-properties::).

Also, you should be catching SQLExceptions in your application and
dealing with them, rather than propagating them all the way until your
application exits, this is just good programming practice. MySQL
Connector/J will set the SQLState (see
`java.sql.SQLException.getSQLState()' in your APIDOCS) to "08S01" when
it encounters network-connectivity issues during the processing of a
query. Your application code should then attempt to re-connect to MySQL
at this point.

The following (simplistic) example shows what code that can handle
these exceptions might look like:

     public void doBusinessOp() throws SQLException {
         Connection conn = null;
         Statement stmt = null;
         ResultSet rs = null;

         //
         // How many times do you want to retry the transaction
         // (or at least _getting_ a connection)?
         //
         int retryCount = 5;

         boolean transactionCompleted = false;

         do {
             try {
                 conn = getConnection(); // assume getting this from a
                                         // javax.sql.DataSource, or the
                                         // java.sql.DriverManager

                 conn.setAutoCommit(false);

                 //
                 // Okay, at this point, the 'retry-ability' of the
                 // transaction really depends on your application logic,
                 // whether or not you're using autocommit (in this case
                 // not), and whether you're using transacational storage
                 // engines
                 //
                 // For this example, we'll assume that it's _not_ safe
                 // to retry the entire transaction, so we set retry
                 // count to 0 at this point
                 //
                 // If you were using exclusively transaction-safe tables,
                 // or your application could recover from a connection going
                 // bad in the middle of an operation, then you would not
                 // touch 'retryCount' here, and just let the loop repeat
                 // until retryCount == 0.
                 //
                 retryCount = 0;

                 stmt = conn.createStatement();

                 String query = "SELECT foo FROM bar ORDER BY baz";

                 rs = stmt.executeQuery(query);

                 while (rs.next()) {
                 }

                 rs.close();
                 rs = null;

                 stmt.close();
                 stmt = null;

                 conn.commit();
                 conn.close();
                 conn = null;

                 transactionCompleted = true;
             } catch (SQLException sqlEx) {

                 //
                 // The two SQL states that are 'retry-able' are 08S01
                 // for a communications error, and 40001 for deadlock.
                 //
                 // Only retry if the error was due to a stale connection,
                 // communications problem or deadlock
                 //

                 String sqlState = sqlEx.getSQLState();

                 if ("08S01".equals(sqlState) || "40001".equals(sqlState)) {
                     retryCount--;
                 } else {
                     retryCount = 0;
                 }
             } finally {
                 if (rs != null) {
                     try {
                         rs.close();
                     } catch (SQLException sqlEx) {
                         // You'd probably want to log this . . .
                     }
                 }

                 if (stmt != null) {
                     try {
                         stmt.close();
                     } catch (SQLException sqlEx) {
                         // You'd probably want to log this as well . . .
                     }
                 }

                 if (conn != null) {
                     try {
                         //
                         // If we got here, and conn is not null, the
                         // transaction should be rolled back, as not
                         // all work has been done

                         try {
                             conn.rollback();
                         } finally {
                             conn.close();
                         }
                     } catch (SQLException sqlEx) {
                         //
                         // If we got an exception here, something
                         // pretty serious is going on, so we better
                         // pass it up the stack, rather than just
                         // logging it. . .

                         throw sqlEx;
                     }
                 }
             }
         } while (!transactionCompleted && (retryCount > 0));
     }

*Note*:

Use of the `autoReconnect' option is not recommended because there is
no safe method of reconnecting to the MySQL server without risking some
corruption of the connection state or database state information.
Instead, you should use a connection pool which will enable your
application to connect to the MySQL server using an available
connection from the pool. The `autoReconnect' facility is deprecated,
and may be removed in a future release.

*20.4.5.3.5: ** I'm trying to use JDBC-2.0 updatable result sets, and I
get an exception saying my result set is not updatable.  *

Because MySQL does not have row identifiers, MySQL Connector/J can only
update result sets that have come from queries on tables that have at
least one primary key, the query must select every primary key and the
query can only span one table (that is, no joins). This is outlined in
the JDBC specification.

Note that this issue only occurs when using updatable result sets, and
is caused because Connector/J is unable to guarantee that it can
identify the correct rows within the result set to be updated without
having a unique reference to each row. There is no requirement to have a
unique field on a table if you are using *Note `UPDATE': update. or
*Note `DELETE': delete. statements on a table where you can
individually specify the criteria to be matched using a `WHERE' clause.

*20.4.5.3.6: ** I cannot connect to the MySQL server using Connector/J,
and I'm sure the connection paramters are correct.  *

Make sure that the `skip-networking' option has not been enabled on
your server. Connector/J must be able to communicate with your server
over TCP/IP, named sockets are not supported. Also ensure that you are
not filtering connections through a Firewall or other network security
system. For more information, see *Note can-not-connect-to-server::.

*20.4.5.3.7: ** I am trying to connect to my MySQL server within my
application, but I get the following error and stack trace: *
     java.net.SocketException
     MESSAGE: Software caused connection abort: recv failed

     STACKTRACE:

     java.net.SocketException: Software caused connection abort: recv failed
     at java.net.SocketInputStream.socketRead0(Native Method)
     at java.net.SocketInputStream.read(Unknown Source)
     at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1392)
     at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:1414)
     at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:625)
     at com.mysql.jdbc.Connection.createNewIO(Connection.java:1926)
     at com.mysql.jdbc.Connection.<init>(Connection.java:452)
     at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:411)

The error probably indicates that you are using a older version of the
Connector/J JDBC driver (2.0.14 or 3.0.x) and you are trying to connect
to a MySQL server with version 4.1x or newer. The older drivers are not
compatible with 4.1 or newer of MySQL as they do not support the newer
authentication mechanisms.

It is likely that the older version of the Connector/J driver exists
within your application directory or your `CLASSPATH' includes the older
Connector/J package.

*20.4.5.3.8: ** My application is deployed through JBoss and I am using
transactions to handle the statements on the MySQL database. Under
heavy loads I am getting a error and stack trace, but these only occur
after a fixed period of heavy activity.  *

This is a JBoss, not Connector/J, issue and is connected to the use of
transactions. Under heavy loads the time taken for transactions to
complete can increase, and the error is caused because you have
exceeded the predefined timeout.

You can increase the timeout value by setting the `TransactionTimeout'
attribute to the `TransactionManagerService' within the
`/conf/jboss-service.xml' file (pre-4.0.3) or `/deploy/jta-service.xml'
for JBoss 4.0.3 or later. See TransactionTimeoute
(http://wiki.jboss.org/wiki/Wiki.jsp?page=TransactionTimeout) within
the JBoss wiki for more information.

*20.4.5.3.9: ** When using `gcj' an `java.io.CharConversionException' is
raised when working with certain character sequences.  *

This is a known issue with `gcj' which raises an exception when it
reaches an unknown character or one it cannot convert. You should add
`useJvmCharsetConverters=true' to your connection string to force
character conversion outside of the `gcj' libraries, or try a different
JDK.

*20.4.5.3.10: ** Updating a table that contains a primary key that is
either *Note `FLOAT': numeric-types. or compound primary key that uses
*Note `FLOAT': numeric-types.  fails to update the table and raises an
exception.  *

Connector/J adds conditions to the `WHERE' clause during an *Note
`UPDATE': update. to check the old values of the primary key. If there
is no match then Connector/J considers this a failure condition and
raises an exception.

The problem is that rounding differences between supplied values and
the values stored in the database may mean that the values never match,
and hence the update fails. The issue will affect all queries, not just
those from Connector/J.

To prevent this issue, use a primary key that does not use *Note
`FLOAT': numeric-types. If you have to use a floating point column in
your primary key use *Note `DOUBLE': numeric-types. or *Note `DECIMAL':
numeric-types. types in place of *Note `FLOAT': numeric-types.

*20.4.5.3.11: ** You get an `ER_NET_PACKET_TOO_LARGE' exception, even
though the binary blob size you want to insert via JDBC is safely below
the `max_allowed_packet' size.  *

This is because the `hexEscapeBlock()' method in
`com.mysql.jdbc.PreparedStatement.streamToBytes()' may almost double
the size of your data.


File: manual.info,  Node: connector-j-support,  Prev: connector-j-usagenotes,  Up: connector-j

20.4.6 Connector/J Support
--------------------------

* Menu:

* connector-j-support-community::  Connector/J Community Support
* connector-j-support-bug-report::  How to Report Connector/J Bugs or Problems
* connector-j-support-changelog::  Connector/J Change History


File: manual.info,  Node: connector-j-support-community,  Next: connector-j-support-bug-report,  Prev: connector-j-support,  Up: connector-j-support

20.4.6.1 Connector/J Community Support
......................................

Sun Microsystems, Inc. provides assistance to the user community by
means of its mailing lists. For Connector/J related issues, you can get
help from experienced users by using the MySQL and Java mailing list.
Archives and subscription information is available online at
`http://lists.mysql.com/java'.

For information about subscribing to MySQL mailing lists or to browse
list archives, visit `http://lists.mysql.com/'. See *Note
mailing-lists::.

Community support from experienced users is also available through the
JDBC Forum (http://forums.mysql.com/list.php?39). You may also find
help from other users in the other MySQL Forums, located at
`http://forums.mysql.com'. See *Note forums::.


File: manual.info,  Node: connector-j-support-bug-report,  Next: connector-j-support-changelog,  Prev: connector-j-support-community,  Up: connector-j-support

20.4.6.2 How to Report Connector/J Bugs or Problems
...................................................

The normal place to report bugs is `http://bugs.mysql.com/', which is
the address for our bugs database. This database is public, and can be
browsed and searched by anyone. If you log in to the system, you will
also be able to enter new reports.

If you have found a sensitive security bug in MySQL, you can send email
to <security@mysql.com>.

Writing a good bug report takes patience, but doing it right the first
time saves time both for us and for yourself. A good bug report,
containing a full test case for the bug, makes it very likely that we
will fix the bug in the next release.

This section will help you write your report correctly so that you do
not waste your time doing things that may not help us much or at all.

If you have a repeatable bug report, please report it to the bugs
database at `http://bugs.mysql.com/'. Any bug that we are able to
repeat has a high chance of being fixed in the next MySQL release.

To report other problems, you can use one of the MySQL mailing lists.

Remember that it is possible for us to respond to a message containing
too much information, but not to one containing too little. People
often omit facts because they think they know the cause of a problem
and assume that some details do not matter.

A good principle is this: If you are in doubt about stating something,
state it. It is faster and less troublesome to write a couple more
lines in your report than to wait longer for the answer if we must ask
you to provide information that was missing from the initial report.

The most common errors made in bug reports are (a) not including the
version number of Connector/J or MySQL used, and (b) not fully
describing the platform on which Connector/J is installed (including
the JVM version, and the platform type and version number that MySQL
itself is installed on).

This is highly relevant information, and in 99 cases out of 100, the
bug report is useless without it. Very often we get questions like,
`Why doesn't this work for me?' Then we find that the feature requested
wasn't implemented in that MySQL version, or that a bug described in a
report has already been fixed in newer MySQL versions.

Sometimes the error is platform-dependent; in such cases, it is next to
impossible for us to fix anything without knowing the operating system
and the version number of the platform.

If at all possible, you should create a repeatable, stanalone testcase
that doesn't involve any third-party classes.

To streamline this process, we ship a base class for testcases with
Connector/J, named 'com.mysql.jdbc.util.BaseBugReport'. To create a
testcase for Connector/J using this class, create your own class that
inherits from com.mysql.jdbc.util.BaseBugReport and override the
methods `setUp()', `tearDown()' and `runTest()'.

In the `setUp()' method, create code that creates your tables, and
populates them with any data needed to demonstrate the bug.

In the `runTest()' method, create code that demonstrates the bug using
the tables and data you created in the `setUp' method.

In the `tearDown()' method, drop any tables you created in the
`setUp()' method.

In any of the above three methods, you should use one of the variants
of the `getConnection()' method to create a JDBC connection to MySQL:

   * `getConnection()' - Provides a connection to the JDBC URL
     specified in `getUrl()'.  If a connection already exists, that
     connection is returned, otherwise a new connection is created.

   * `getNewConnection()' - Use this if you need to get a new
     connection for your bug report (that is, there is more than one
     connection involved).

   * `getConnection(String url)' - Returns a connection using the given
     URL.

   * `getConnection(String url, Properties props)' - Returns a
     connection using the given URL and properties.

If you need to use a JDBC URL that is different from
'jdbc:mysql:///test', override the method `getUrl()' as well.

Use the `assertTrue(boolean expression)' and `assertTrue(String
failureMessage, boolean expression)' methods to create conditions that
must be met in your testcase demonstrating the behavior you are
expecting (vs. the behavior you are observing, which is why you are
most likely filing a bug report).

Finally, create a `main()' method that creates a new instance of your
testcase, and calls the `run' method:

     public static void main(String[] args) throws Exception {
           new MyBugReport().run();
      }

Once you have finished your testcase, and have verified that it
demonstrates the bug you are reporting, upload it with your bug report
to `http://bugs.mysql.com/'.


File: manual.info,  Node: connector-j-support-changelog,  Prev: connector-j-support-bug-report,  Up: connector-j-support

20.4.6.3 Connector/J Change History
...................................

The Connector/J Change History (Changelog) is located with the main
Changelog for MySQL. See *Note cj-news::.


File: manual.info,  Node: connector-mxj,  Next: connector-cpp,  Prev: connector-j,  Up: connectors-apis

20.5 MySQL Connector/MXJ
========================

* Menu:

* connector-mxj-overview::       Connector/MXJ Overview
* connector-mxj-versions::       Connector/MXJ Versions
* connector-mxj-install::        Connector/MXJ Installation
* connector-mxj-configuration::  Connector/MXJ Configuration
* connector-mxj-ref::            Connector/MXJ Reference
* connector-mxj-usagenotes::     Connector/MXJ Notes and Tips
* connector-mxj-support::        Connector/MXJ Support

MySQL Connector/MXJ is a Java Utility package for deploying and
managing a MySQL database. Deploying and using MySQL can be as easy as
adding an additional parameter to the JDBC connection url, which will
result in the database being started when the first connection is made.
This makes it easy for Java developers to deploy applications which
require a database by reducing installation barriers for their
end-users.

MySQL Connector/MXJ makes the MySQL database appear to be a java-based
component. It does this by determining what platform the system is
running on, selecting the appropriate binary, and launching the
executable. It will also optionally deploy an initial database, with
any specified parameters.

Included are instructions for use with a JDBC driver and deploying as a
JMX MBean to JBoss.

You can download sources and binaries from:
`http://dev.mysql.com/downloads/connector/mxj/'

This a beta release and feedback is welcome and encouraged.

Please send questions or comments to the MySQL and Java mailing list
(http://lists.mysql.com/java).


File: manual.info,  Node: connector-mxj-overview,  Next: connector-mxj-versions,  Prev: connector-mxj,  Up: connector-mxj

20.5.1 Connector/MXJ Overview
-----------------------------

Connector/MXJ consists of a Java class, a copy of the `mysqld' binary
for a specific list of platforms, and associated files and support
utilities. The Java class controls the initialization of an instance of
the embedded `mysqld' binary, and the ongoing management of the
`mysqld' process. The entire sequence and management can be controlled
entirely from within Java using the Connector/MXJ Java classes. You can
see an overview of the contents of the Connector/MXJ package in the
figure below.

Connector/MXJ Overview

It is important to note that Connector/MXJ is not an embedded version
of MySQL, or a version of MySQL written as part of a Java class.
Connector/MXJ works through the use of an embedded, compiled binary of
`mysqld' as would normally be used when deploying a standard MySQL
installation.

It is the Connector/MXJ wrapper, support classes and tools, that enable
Connector/MXJ to appear as a MySQL instance.

When Connector/MXJ is initialized, the corresponding `mysqld' binary
for the current platform is extracted, along with a pre-configured data
directed. Both are contained within the Connector/MXJ JAR file. The
`mysqld' instance is then started, with any additional options as
specified during the initialization, and the MySQL database becomes
accessible.

Because Connector/MXJ works in combination with Connector/J, you can
access and integrate with the MySQL instance through a JDBC connection.
When you have finished with the server, the instance is terminated,
and, by default, any data created during the session is retained within
the temporary directory created when the instance was started.

Connector/MXJ and the embedded `mysqld' instance can be deployed in a
number of environments where relying on an existing database, or
installing a MySQL instance would be impossible, including CD-ROM
embedded database applications and temporary database requirements
within a Java-based application environment.


File: manual.info,  Node: connector-mxj-versions,  Next: connector-mxj-install,  Prev: connector-mxj-overview,  Up: connector-mxj

20.5.2 Connector/MXJ Versions
-----------------------------

   * Connector/MXJ 5.x, currently in beta status, includes `mysqld'
     version 5.x and includes binaries for Linux x86, Mac OS X PPC,
     Windows XP/NT/2000 x86 and Solaris SPARC. Connector/MXJ 5.x
     requires the Connector/J 5.x package.

     The exact version of `mysqld' included depends on the version of
     Connector/MXJ

       1. Connector/MXJ v5.0.3 included MySQL v5.0.22

       2. Connector/MXJ v5.0.4 includes MySQL v5.0.27 (Community) or
          MySQL v5.0.32 (Enterprise)

       3. Connector/MXJ v5.0.6 includes MySQL 5.0.37 (Community)

       4. Connector/MXJ v5.0.7 includes MySQL 5.0.41 (Community) or
          MySQL 5.0.42 (Enterprise)

       5. Connector/MXJ v5.0.8 includes MySQL 5.0.45 (Community) or
          MySQL 5.0.46 (Enterprise)

       6. Connector/MXJ v5.0.9 includes MySQL 5.0.51a (Community) or
          MySQL 5.0.54 (Enterprise)

   * Connector/MXJ 1.x includes `mysqld' version 4.1.13 and includes
     binaries for Linux x86, Windows XP/NT/2000 x86 and Solaris SPARC.
     Connector/MXJ 1.x requires the Connector/J 3.x package.

A summary of the different MySQL versions supplied with each
Connector/MXJ release are shown in the table.

Connector/MXJ Version                MySQL Version(s)
5.0.8                                5.0.45 (CS), 5.0.46 (ES)
5.0.7                                5.0.41 (CS), 5.0.42 (ES)
5.0.6                                5.0.37 (CS), 5.0.40 (ES)
5.0.5                                5.0.37 (CS), 5.0.36 (ES)
5.0.4                                5.0.27 (CS), 5.0.32 (ES)
5.0.3                                5.0.22
5.0.2                                5.0.19

This guide provides information on the Connector/MXJ 5.x release.  For
information on using the older releases, please see the documentation
included with the appropriate distribution.


File: manual.info,  Node: connector-mxj-install,  Next: connector-mxj-configuration,  Prev: connector-mxj-versions,  Up: connector-mxj

20.5.3 Connector/MXJ Installation
---------------------------------

* Menu:

* connector-mxj-install-platforms::  Supported Platforms
* connector-mxj-install-base::   Connector/MXJ Base Installation
* connector-mxj-install-quickstart::  Connector/MXJ Quick Start Guide
* connector-mxj-install-class::  Deploying Connector/MXJ using Driver Launch
* connector-mxj-install-jboss::  Deploying Connector/MXJ within JBoss
* connector-mxj-installation-test::  Verifying Installation using JUnit

Connector/MXJ does not have a installation application or process, but
there are some steps you can follow to make the installation and
deployment of Connector/MXJ easier.

Before you start, there are some baseline requirements for

   * Java Runtime Environment (v1.4.0 or newer) if you are only going
     to deploy the package.

   * Java Development Kit (v1.4.0 or newer) if you want to build
     Connector/MXJ from source.

   * Connector/J 5.0 or newer.

Depending on your target installation/deployment environment you may
also require:

   * JBoss - 4.0rc1 or newer

   * Apache Tomcat - 5.0 or newer

   * Sun's JMX reference implementation version 1.2.1 (from
     `http://java.sun.com/products/JavaManagement/')


File: manual.info,  Node: connector-mxj-install-platforms,  Next: connector-mxj-install-base,  Prev: connector-mxj-install,  Up: connector-mxj-install

20.5.3.1 Supported Platforms
............................

Connector/MXJ is compatible with any platform supporting Java and
MySQL. By default, Connector/MXJ incorporates the `mysqld' binary for a
select number of platforms which differs by version. The following
platforms have been tested and working as deployment platforms. Support
for all the platforms listed below is not included by default.

   * Linux (i386)

   * FreeBSD (i386)

   * Windows NT (x86), Windows 2000 (x86), Windows XP (x86), Windows
     Vista (x86)

   * Solaris 8, SPARC 32-bit (compatible with Solaris 8, Solaris 9 and
     Solaris 10 on SPARC 32-bit and 64-bit platforms)

   * Mac OS X (PowerPC and Intel)

The Connector/MXJ 5.0.8 release includes *Note `mysqld': mysqld.
binaries for the following platforms by as standard:

   * Linux (i386)

   * Windows (x86), compatible with Windows NT, Windows 2000, Windows
     XP , Windows Vista

   * Solaris 8, SPARC 32-bit (compatible with Solaris 8, Solaris 9 and
     Solaris 10 on SPARC 32-bit and 64-bit platforms)

   * Mac OS X (PowerPC and Intel)

For more information on packaging your own Connector/MXJ with the
platforms you require, see *Note connector-mxj-usagenotes-packaging::


File: manual.info,  Node: connector-mxj-install-base,  Next: connector-mxj-install-quickstart,  Prev: connector-mxj-install-platforms,  Up: connector-mxj-install

20.5.3.2 Connector/MXJ Base Installation
........................................

Because there is no formal installation process, the method,
installation directory, and access methods you use for Connector/MXJ
are entirely up to your individual requirements.

To perform a basic installation, choose a target directory for the
files included in the Connector/MXJ package. On Unix/Linux systems you
may opt to use a directory such as `/usr/local/connector-mxj'; On
Windows, you may want to install the files in the base directory,
`C:\Connector-MXJ', or within the `Program Files' directory.

To install the files, for a Connector/MXJ 5.0.4 installation:

  1. Download the Connector/MXJ package, either in Tar/Gzip format
     (ideal for Unix/Linux systems) or Zip format (Windows).

  2. Extract the files from the package. This will create a directory
     `mysql-connector-mxj-gpl-[ver]'. Copy and optionally rename this
     directory to your desired location.

  3. For best results, you should update your global `CLASSPATH'
     variable with the location of the required `jar' files.

     Within Unix/Linux you can do this globally by editing the global
     shell profile, or on a user by user basis by editing their
     individual shell profile.

     On Windows 2000, Windows NT and Windows XP, you can edit the
     global `CLASSPATH' by editing the `Environment Variables'
     configured through the `System' control panel.

For Connector/MXJ 5.0.6 and later you need the following JAR files in
your `CLASSPATH':

  1. `mysql-connector-mxj-gpl-[ver].jar' -- contains the main
     Connector/MXJ classes.

  2. `mysql-connector-mxj-gpl-[ver]-db-files.jar' -- contains the
     embedded `mysqld' and database files.

  3. `aspectjrt.jar' -- the AspectJ runtime library, located in
     `lib/aspectjrt.jar' in the Connector/MXJ package.

  4. `mysql-connector-java-[ver]-bin.jar' -- Connector/J, see *Note
     connector-j::.

For Connector/MXJ 5.0.4 and later you need the following JAR files in
your `CLASSPATH':

  1. `connector-mxj.jar' -- contains the main Connector/MXJ classes.

  2. `connector-mxj-db-files.jar' -- contains the embedded `mysqld' and
     database files.

  3. `aspectjrt.jar' -- the AspectJ runtime library, located in
     `lib/aspectjrt.jar' in the Connector/MXJ package.

  4. `mysql-connector-mxj-gpl-[ver].jar' -- Connector/J, see *Note
     connector-j::.

For Connector/MXJ 5.0.3 and earlier, you need the following JAR files:

  1. `connector-mxj.jar'

  2. `aspectjrt.jar' -- the AspectJ runtime library, located in
     `lib/aspectjrt.jar' in the Connector/MXJ package.

  3. `mysql-connector-mxj-gpl-[ver].jar' -- Connector/J, see *Note
     connector-j::.


File: manual.info,  Node: connector-mxj-install-quickstart,  Next: connector-mxj-install-class,  Prev: connector-mxj-install-base,  Up: connector-mxj-install

20.5.3.3 Connector/MXJ Quick Start Guide
........................................

Once you have extracted the Connector/MXJ and Connector/J components
you can run one of the sample applications that initiates a MySQL
instance. You can test the installation by running the
`ConnectorMXJUrlTestExample':

     shell> java ConnectorMXJUrlTestExample
     jdbc:mysql:mxj://localhost:3336/our_test_app?server.basedir»
         =/var/tmp/test-mxj&createDatabaseIfNotExist=true&server.initialize-user=true
     [/var/tmp/test-mxj/bin/mysqld][--no-defaults][--port=3336][--socket=mysql.sock]»
         [--basedir=/var/tmp/test-mxj][--datadir=/var/tmp/test-mxj/data]»
         [--pid-file=/var/tmp/test-mxj/data/MysqldResource.pid]
     [MysqldResource] launching mysqld (driver_launched_mysqld_1)
     InnoDB: The first specified data file ./ibdata1 did not exist:
     InnoDB: a new database to be created!
     080220  9:40:20  InnoDB: Setting file ./ibdata1 size to 10 MB
     InnoDB: Database physically writes the file full: wait...
     080220  9:40:20  InnoDB: Log file ./ib_logfile0 did not exist: new to be created
     InnoDB: Setting log file ./ib_logfile0 size to 5 MB
     InnoDB: Database physically writes the file full: wait...
     080220  9:40:20  InnoDB: Log file ./ib_logfile1 did not exist: new to be created
     InnoDB: Setting log file ./ib_logfile1 size to 5 MB
     InnoDB: Database physically writes the file full: wait...
     InnoDB: Doublewrite buffer not found: creating new
     InnoDB: Doublewrite buffer created
     InnoDB: Creating foreign key constraint system tables
     InnoDB: Foreign key constraint system tables created
     080220  9:40:21  InnoDB: Started; log sequence number 0 0
     080220  9:40:21 [Note] /var/tmp/test-mxj/bin/mysqld: ready for connections.
     Version: '5.0.51a'  socket: 'mysql.sock'  port: 3336  MySQL Community Server (GPL)
     [MysqldResource] mysqld running as process: 2238
     ------------------------
     SELECT VERSION()
     ------------------------
     5.0.51a
     ------------------------
     [MysqldResource] stopping mysqld (process: 2238)
     080220  9:40:27 [Note] /var/tmp/test-mxj/bin/mysqld: Normal shutdown

     080220  9:40:27  InnoDB: Starting shutdown...
     080220  9:40:29  InnoDB: Shutdown completed; log sequence number 0 43655
     080220  9:40:29 [Note] /var/tmp/test-mxj/bin/mysqld: Shutdown complete

     [MysqldResource] shutdown complete

The above output shows an instance of MySQL starting, the necessary
files being created (log files, InnoDB data files) and the MySQL
database entering the running state. The instance is then shutdown by
Connector/MXJ before the example terminates.

*Warning*:

You should avoid running your Connector/MXJ application as the `root'
user, because this will cause the *Note `mysqld': mysqld. to also be
executed with root privileges. For more information, see *Note
changing-mysql-user::.


File: manual.info,  Node: connector-mxj-install-class,  Next: connector-mxj-install-jboss,  Prev: connector-mxj-install-quickstart,  Up: connector-mxj-install

20.5.3.4 Deploying Connector/MXJ using Driver Launch
....................................................

Connector/MXJ and Connector/J work together to enable you to launch an
instance of the `mysqld' server through the use of a keyword in the
JDBC connection string.  Deploying Connector/MXJ within a Java
application can be automated through this method, making the deployment
of Connector/MXJ a simple process:

  1. Download and unzip Connector/MXJ, add
     `mysql-connector-mxj-gpl-[ver].jar' to the `CLASSPATH'.

     If you are using Connector/MXJ v5.0.4 or later you will also need
     to add the `mysql-connector-mxj-gpl-[ver]-db-files.jar' file to
     your `CLASSPATH'.

  2. To the JDBC connection string, embed the `mxj' keyword, for
     example: `jdbc:mysql:mxj://localhost:PORT/DBNAME'.

For more details, see *Note connector-mxj-configuration::.


File: manual.info,  Node: connector-mxj-install-jboss,  Next: connector-mxj-installation-test,  Prev: connector-mxj-install-class,  Up: connector-mxj-install

20.5.3.5 Deploying Connector/MXJ within JBoss
.............................................

For deployment within a JBoss environment, you must configure the JBoss
environment to use the Connector/MXJ component within the JDBC
parameters:

  1. Download Connector/MXJ and copy the
     `mysql-connector-mxj-gpl-[ver].jar' file to the
     `$JBOSS_HOME/server/default/lib' directory.

     If you are using Connector/MXJ v5.0.4 or later you will also need
     to copy the `mysql-connector-mxj-gpl-[ver]-db-files.jar' file to
     `$JBOSS_HOME/server/default/lib'.

  2. Download Connector/J and copy the
     `mysql-connector-java-5.1.5-bin.jar' file to the
     `$JBOSS_HOME/server/default/lib' directory.

  3. Create an MBean service xml file in the
     `$JBOSS_HOME/server/default/deploy' directory with any attributes
     set, for instance the `datadir' and `autostart'.

  4. Set the JDBC parameters of your web application to use:

          String driver = "com.mysql.jdbc.Driver";
          String url = "jdbc:mysql:///test?propertiesTransform="+
                       "com.mysql.management.jmx.ConnectorMXJPropertiesTransform";
          String user = "root";
          String password = "";
          Class.forName(driver);
          Connection conn = DriverManager.getConnection(url, user, password);

You may wish to create a separate users and database table spaces for
each application, rather than using "root and test".

We highly suggest having a routine backup procedure for backing up the
database files in the `datadir'.


File: manual.info,  Node: connector-mxj-installation-test,  Prev: connector-mxj-install-jboss,  Up: connector-mxj-install

20.5.3.6 Verifying Installation using JUnit
...........................................

* Menu:

* connector-mxj-installation-test-requirements::  JUnit Test Requirements
* connector-mxj-installation-test-running::  Running the JUnit Tests

The best way to ensure that your platform is supported is to run the
JUnit tests. These will test the Connector/MXJ classes and the
associated components.


File: manual.info,  Node: connector-mxj-installation-test-requirements,  Next: connector-mxj-installation-test-running,  Prev: connector-mxj-installation-test,  Up: connector-mxj-installation-test

20.5.3.7 JUnit Test Requirements
................................

The first thing to do is make sure that the components will work on the
platform. The MysqldResource class is really a wrapper for a native
version of MySQL, so not all platforms are supported. At the time of
this writing, Linux on the i386 architecture has been tested and seems
to work quite well, as does OS X v10.3. There has been limited testing
on Windows and Solaris.

Requirements:

  1. JDK-1.4 or newer (or the JRE if you aren't going to be compiling
     the source or JSPs).

  2. MySQL Connector/J version 5.0 or newer (from
     `http://dev.mysql.com/downloads/connector/j/') installed and
     available via your CLASSPATH.

  3. The `javax.management' classes for JMX version 1.2.1, these are
     present in the following application servers:

        * JBoss - 4.0rc1 or newer.

        * Apache Tomcat - 5.0 or newer.

        * Sun's JMX reference implementation version 1.2.1 (from
          `http://java.sun.com/products/JavaManagement/').

  4. JUnit 3.8.1 (from `http://www.junit.org/').

If building from source, All of the requirements from above, plus:

  1. Ant version 1.5 or newer (download from `http://ant.apache.org/').


File: manual.info,  Node: connector-mxj-installation-test-running,  Prev: connector-mxj-installation-test-requirements,  Up: connector-mxj-installation-test

20.5.3.8 Running the JUnit Tests
................................

  1. The tests attempt to launch MySQL on the port 3336. If you have a
     MySQL running, it may conflict, but this isn't very likely because
     the default port for MySQL is 3306.  However, You may set the
     "c-mxj_test_port" Java property to a port of your choosing.
     Alternatively, you may wish to start by shutting down any
     instances of MySQL you have running on the target machine.

     The tests suppress output to the console by default. For verbose
     output, you may set the "c-mxj_test_silent" Java property to
     "false".

  2. To run the JUnit test suite, the $CLASSPATH must include the
     following:

        * JUnit

        * JMX

        * Connector/J

        * MySQL Connector/MXJ

  3. If `connector-mxj.jar' is not present in your download, unzip
     MySQL Connector/MXJ source archive.

          cd mysqldjmx
          ant dist

     Then add `$TEMP/cmxj/stage/connector-mxj/connector-mxj.jar' to the
     CLASSPATH.

  4. if you have `junit', execute the unit tests. From the command
     line, type:

          java com.mysql.management.AllTestsSuite

     The output should look something like this:

          .........................................
          .........................................
          ..........
          Time: 259.438

          OK (101 tests)

     Note that the tests are a bit slow near the end, so please be
     patient.


File: manual.info,  Node: connector-mxj-configuration,  Next: connector-mxj-ref,  Prev: connector-mxj-install,  Up: connector-mxj

20.5.4 Connector/MXJ Configuration
----------------------------------

* Menu:

* connector-mxj-configuration-driver-launched::  Running as part of the JDBC Driver
* connector-mxj-configuration-java-object::  Running within a Java Object
* connector-mxj-configuration-options::  Setting server options


File: manual.info,  Node: connector-mxj-configuration-driver-launched,  Next: connector-mxj-configuration-java-object,  Prev: connector-mxj-configuration,  Up: connector-mxj-configuration

20.5.4.1 Running as part of the JDBC Driver
...........................................

A feature of the MySQL Connector/J JDBC driver is the ability to
specify a connection to an embedded Connector/MXJ instance through the
use of the mxj keyword in the JDBC connection string.

In the following example, we have a program which creates a connection,
executes a query, and prints the result to the System.out. The MySQL
database will be deployed and started as part of the connection
process, and shutdown as part of the finally block.

You can find this file in the Connector/MXJ package as
`src/ConnectorMXJUrlTestExample.java'.

     import java.io.File;
     import java.sql.Connection;
     import java.sql.DriverManager;

     import com.mysql.management.driverlaunched.ServerLauncherSocketFactory;
     import com.mysql.management.util.QueryUtil;

     public class ConnectorMXJUrlTestExample {
       public static String DRIVER = "com.mysql.jdbc.Driver";

       public static String JAVA_IO_TMPDIR = "java.io.tmpdir";

       public static void main(String[] args) throws Exception {
         File ourAppDir = new File(System.getProperty(JAVA_IO_TMPDIR));
         File databaseDir = new File(ourAppDir, "test-mxj");
         int port = Integer.parseInt(System.getProperty("c-mxj_test_port", "3336"));
         String dbName = "our_test_app";

         String url = "jdbc:mysql:mxj://localhost:" + port + "/" + dbName //
           + "?" + "server.basedir=" + databaseDir //
           + "&" + "createDatabaseIfNotExist=true"//
           + "&" + "server.initialize-user=true" //
         ;

         System.out.println(url);

         String userName = "alice";
         String password = "q93uti0opwhkd";

         Class.forName(DRIVER);
         Connection conn = null;
         try {
           conn = DriverManager.getConnection(url, userName, password);
           String sql = "SELECT VERSION()";
           String queryForString = new QueryUtil(conn).queryForString(sql);

           System.out.println("------------------------");
           System.out.println(sql);
           System.out.println("------------------------");
           System.out.println(queryForString);
           System.out.println("------------------------");
           System.out.flush();
           Thread.sleep(100); // wait for System.out to finish flush
         } finally {
           try {
             if (conn != null)
                conn.close();
           } catch (Exception e) {
             e.printStackTrace();
           }

           ServerLauncherSocketFactory.shutdown(databaseDir, null);
         }
       }
     }

To run the above program, be sure to have connector-mxj.jar and
Connector/J in the CLASSPATH. Then type:

     java ConnectorMXJTestExample


File: manual.info,  Node: connector-mxj-configuration-java-object,  Next: connector-mxj-configuration-options,  Prev: connector-mxj-configuration-driver-launched,  Up: connector-mxj-configuration

20.5.4.2 Running within a Java Object
.....................................

If you have a java application and wish to `embed' a MySQL database,
make use of the `com.mysql.management.MysqldResource' class directly.
This class may be instantiated with the default (no argument)
constructor, or by passing in a java.io.File object representing the
directory you wish the server to be "unzipped" into. It may also be
instantiated with printstreams for "stdout" and "stderr" for logging.

Once instantiated, a `java.util.Map', the object will be able to
provide a `java.util.Map' of server options appropriate for the
platform and version of MySQL which you will be using.

The MysqldResource enables you to "start" MySQL with a `java.util.Map'
of server options which you provide, as well as "shutdown" the
database. The following example shows a simplistic way to embed MySQL
in an application using plain java objects.

You can find this file in the Connector/MXJ package as
`src/ConnectorMXJObjectTestExample.java'.

     import java.io.File;
     import java.sql.Connection;
     import java.sql.DriverManager;
     import java.util.HashMap;
     import java.util.Map;

     import com.mysql.management.MysqldResource;
     import com.mysql.management.MysqldResourceI;
     import com.mysql.management.util.QueryUtil;

     public class ConnectorMXJObjectTestExample {
         public static final String DRIVER = "com.mysql.jdbc.Driver";

         public static final String JAVA_IO_TMPDIR = "java.io.tmpdir";

         public static void main(String[] args) throws Exception {
             File ourAppDir = new File(System.getProperty(JAVA_IO_TMPDIR));
             File databaseDir = new File(ourAppDir, "mysql-mxj");
             int port = Integer.parseInt(System.getProperty("c-mxj_test_port",
                     "3336"));
             String userName = "alice";
             String password = "q93uti0opwhkd";

             MysqldResource mysqldResource = startDatabase(databaseDir, port,
                     userName, password);

             Class.forName(DRIVER);
             Connection conn = null;
             try {
                 String dbName = "our_test_app";
                 String url = "jdbc:mysql://localhost:" + port + "/" + dbName //
                         + "?" + "createDatabaseIfNotExist=true"//
                 ;
                 conn = DriverManager.getConnection(url, userName, password);
                 String sql = "SELECT VERSION()";
                 String queryForString = new QueryUtil(conn).queryForString(sql);

                 System.out.println("------------------------");
                 System.out.println(sql);
                 System.out.println("------------------------");
                 System.out.println(queryForString);
                 System.out.println("------------------------");
                 System.out.flush();
                 Thread.sleep(100); // wait for System.out to finish flush
             } finally {
                 try {
                     if (conn != null) {
                         conn.close();
                     }
                 } catch (Exception e) {
                     e.printStackTrace();
                 }
                 try {
                     mysqldResource.shutdown();
                 } catch (Exception e) {
                     e.printStackTrace();
                 }
             }
         }

         public static MysqldResource startDatabase(File databaseDir, int port,
                 String userName, String password) {
             MysqldResource mysqldResource = new MysqldResource(databaseDir);

             Map database_options = new HashMap();
             database_options.put(MysqldResourceI.PORT, Integer.toString(port));
             database_options.put(MysqldResourceI.INITIALIZE_USER, "true");
             database_options.put(MysqldResourceI.INITIALIZE_USER_NAME, userName);
             database_options.put(MysqldResourceI.INITIALIZE_PASSWORD, password);

             mysqldResource.start("test-mysqld-thread", database_options);

             if (!mysqldResource.isRunning()) {
                 throw new RuntimeException("MySQL did not start.");
             }

             System.out.println("MySQL is running.");

             return mysqldResource;
         }
     }


File: manual.info,  Node: connector-mxj-configuration-options,  Prev: connector-mxj-configuration-java-object,  Up: connector-mxj-configuration

20.5.4.3 Setting server options
...............................

Of course there are many options we may wish to set for a MySQL
database. These options may be specified as part of the JDBC connection
string simply by prefixing each server option with `server.'. In the
following example we set two driver parameters and two server
parameters:

             String url = "jdbc:mysql://" + hostColonPort + "/"
                     + "?"
                     + "cacheServerConfiguration=true"
                     + "&"
                     + "useLocalSessionState=true"
                     + "&"
                     + "server.basedir=/opt/myapp/db"
                     + "&"
                     + "server.datadir=/mnt/bigdisk/myapp/data";

Starting with Connector/MXJ 5.0.6 you can use the `initializer-user'
property to a connection string. If set to true, the default anonymous
and root users will be removed and the user/password combination from
the connection URL will be used to create a new user. For example:

             String url = "jdbc:mysql:mxj://localhost:" + port
             + "/alice_db"
             + "?server.datadir=" + dataDir.getPath()
             + "&server.initialize-user=true"
             + "&createDatabaseIfNotExist=true"
             ;


File: manual.info,  Node: connector-mxj-ref,  Next: connector-mxj-usagenotes,  Prev: connector-mxj-configuration,  Up: connector-mxj

20.5.5 Connector/MXJ Reference
------------------------------

* Menu:

* connector-mxj-ref-mysqldresource-ctor::  MysqldResource Constructors
* connector-mxj-ref-mysqldresource-methods::  MysqldResource Methods

The following sections include detailed information on the different
API interfaces to Connector/MXJ.


File: manual.info,  Node: connector-mxj-ref-mysqldresource-ctor,  Next: connector-mxj-ref-mysqldresource-methods,  Prev: connector-mxj-ref,  Up: connector-mxj-ref

20.5.5.1 MysqldResource Constructors
....................................

The `MysqldResource' class supports three different constructor forms:

   * `public MysqldResource(File baseDir, File dataDir, String
     mysqlVersionString, PrintStream out, PrintStream err)'

     Enables you to set the base directory, data directory, select a
     server by its version string, standard out and standard error.

   * `public MysqldResource(File baseDir, File dataDir, String
     mysqlVersionString) '

     Enables you to set the base directory, data directory and select a
     server by its version string. Output for standard out and standard
     err are directed to System.out and System.err.

   * `public MysqldResource(File baseDir, File dataDir) '

     Enables you to set the base directory and data directory.  The
     default MySQL version is selected, and output for standard out and
     standard err are directed to System.out and System.err.

   * `public MysqldResource(File baseDir);'

     Allows the setting of the "basedir" to deploy the MySQL files to.
     Output for standard out and standard err are directed to
     System.out and System.err.

   * `public MysqldResource();'

     The basedir is defaulted to a subdirectory of the java.io.tempdir.
     Output for standard out and standard err are directed to
     System.out and System.err;


File: manual.info,  Node: connector-mxj-ref-mysqldresource-methods,  Prev: connector-mxj-ref-mysqldresource-ctor,  Up: connector-mxj-ref

20.5.5.2 MysqldResource Methods
...............................

MysqldResource API includes the following methods:

   * `void start(String threadName, Map mysqldArgs);'

     Deploys and starts MySQL. The "threadName" string is used to name
     the thread which actually performs the execution of the MySQL
     command line. The map is the set of arguments and their values to
     be passed to the command line.

   * `void shutdown(); '

     Shuts down the MySQL instance managed by the MysqldResource object.

   * ` Map getServerOptions(); '

     Returns a map of all the options and their current (or default, if
     not running) options available for the MySQL database.

   * ` boolean isRunning(); '

     Returns true if the MySQL database is running.

   * ` boolean isReadyForConnections(); '

     Returns true once the database reports that is ready for
     connections.

   * ` void setKillDelay(int millis); '

     The default `Kill Delay' is 30 seconds. This represents the amount
     of time to wait between the initial request to shutdown and
     issuing a `force kill' if the database has not shutdown by itself.

   * ` void addCompletionListenser(Runnable listener); '

     Allows for applications to be notified when the server process
     completes. Each "listener" will be fired off in its own thread.

   * ` String getVersion(); '

     Returns the version of MySQL.

   * ` void setVersion(int MajorVersion, int minorVersion, int
     patchLevel); '

     The standard distribution comes with only one version of MySQL
     packaged. However, it is possible to package multiple versions,
     and specify which version to use.


File: manual.info,  Node: connector-mxj-usagenotes,  Next: connector-mxj-support,  Prev: connector-mxj-ref,  Up: connector-mxj

20.5.6 Connector/MXJ Notes and Tips
-----------------------------------

* Menu:

* connector-mxj-usagenotes-packaging::  Creating your own Connector/MXJ Package
* connector-mxj-usagenotes-customdb::  Deploying Connector/MXJ with a pre-configured database
* connector-mxj-usagenotes-jmx-agent::  Running within a JMX Agent (custom)
* connector-mxj-usagenotes-standard-environment::  Deployment in a standard JMX Agent environment (JBoss)

This section contains notes and tips on using the Connector/MXJ
component within your applications.


File: manual.info,  Node: connector-mxj-usagenotes-packaging,  Next: connector-mxj-usagenotes-customdb,  Prev: connector-mxj-usagenotes,  Up: connector-mxj-usagenotes

20.5.6.1 Creating your own Connector/MXJ Package
................................................

If you want to create a custom Connector/MXJ package that includes a
specific `mysqld' version or platform then you must extract and rebuild
the `mysql-connector-mxj.jar' (Connector/MXJ v5.0.3 or earlier) or
`mysql-connector-mxj-gpl-[ver]-db-files.jar' (Connector/MXJ v5.0.4 or
later) file.

First, you should create a new directory into which you can extract the
current `connector-mxj.jar':

     shell> mkdir custom-mxj
     shell> cd custom-mxj
     shell> jar -xf connector-mxj.jar
     shell> ls
     5-0-22/
     ConnectorMXJObjectTestExample.class
     ConnectorMXJUrlTestExample.class
     META-INF/
     TestDb.class
     com/
     kill.exe

If you are using Connector/MXJ v5.0.4 or later, you should unpack the
`connector-mxj-db-files.jar':

     shell> mkdir custom-mxj
     shell> cd custom-mxj
     shell> jar -xf connector-mxj-db-files.jar
     shell> ls
     5-0-51a/
     META-INF/
     connector-mxj.properties

The MySQL version directory, `5-0-22' or `5-0-51a' in the preceding
examples, contains all of the files used to create an instance of MySQL
when Connector/MXJ is executed. All of the files in this directory are
required for each version of MySQL that you want to embed.  Note as
well the format of the version number, which uses hyphens instead of
periods to separate the version number components.

Within the version specific directory are the platform specific
directories, and archives of the `data' and `share' directory required
by MySQL for the various platforms. For example, here is the listing
for the default Connector/MXJ package:

     shell>> ls
     Linux-i386/
     META-INF/
     Mac_OS_X-ppc/
     SunOS-sparc/
     Win-x86/
     com/
     data_dir.jar
     share_dir.jar
     win_share_dir.jar

Platform specific directories are listed by their OS and platform - for
example the `mysqld' for Mac OS X PowerPC is located within the
`Mac_OS_X-ppc' directory. You can delete directories from this location
that you do not require, and add new directories for additional
platforms that you want to support.

To add a platform specific `mysqld', create a new directory with the
corresponding name for your operating system/platform. For example, you
could add a directory for Mac OS X/Intel using the directory
`Mac_OS_X-i386'.

On Unix systems, you can determine the platform using `uname':

     shell> uname -p
     i386

In Connector/MXJ v5.0.9 and later, an additional
`platform-map.properties' file is used to associate a specific platform
and operating system combination with the directory in which the
`mysqld' for that combination is located. The determined operating
system and platform are on the left, and the directory name where the
appropriate mysqld is located is on the right. You can see a sample of
the file below:

     Linux-i386=Linux-i386
     Linux-x86=Linux-i386
     Linux-i686=Linux-i386
     Linux-x86_64=Linux-i386
     Linux-ia64=Linux-i386

     #Linux-ppc=Linux-ppc
     #Linux-ppc64=Linux-ppc

     Mac_OS_X-i386=Mac_OS_X-i386
     Mac_OS_X-ppc=Mac_OS_X-ppc
     Rhapsody-PowerPC=Mac_OS_X-ppc
     #Mac_OS-PowerPC=
     #macos-PowerPC=
     #MacOS-PowerPC=

     SunOS-sparc=SunOS-sparc
     Solaris-sparc=SunOS-sparc
     SunOS-x86=SunOS-x86
     Solaris-x86=SunOS-x86

     FreeBSD-x86=FreeBSD-x86

     Windows_Vista-x86=Win-x86
     Windows_2003-x86=Win-x86
     Windows_XP-x86=Win-x86
     Windows_2000-x86=Win-x86
     Windows_NT-x86=Win-x86
     Windows_NT_(unknown)-x86=Win-x86

Now you need to download or compile `mysqld' for the MySQL version and
platform you want to include in your custom `connector-mxj.jar' package
into the new directory.

Create a file called `version.txt' in the OS/platform directory you
have just created that contains the version string/path of the mysqld
binary. For example:

     mysql-5.0.22-osx10.3-i386/bin/mysqld

You can now recreate the `connector-mxj.jar' file with the added
`mysqld':

     shell> cd custom-mxj
     shell> jar -cf ../connector-mxj.jar *

For Connector/MXJ v5.0.4 and later, you should repackage to the
`connector-mxj-db-files.jar':

     shell> cd custom-mxj
     shell> jar -cf ../mysql-connector-mxj-gpl-[ver]-db-files.jar *

You should test this package using the steps outlined in *Note
connector-mxj-install-quickstart::.

*Note*:

Because the `mysql-connector-mxj-gpl-[ver]-db-files.jar' file is
separate from the main Connector/MXJ classes you can distribute
different `mysql-connector-mxj-gpl-[ver]-db-files.jar' files to
different hotsts or for different projects without having to create a
completely new main `mysql-connector-mxj-gpl-[ver].jar' file for each
one.


File: manual.info,  Node: connector-mxj-usagenotes-customdb,  Next: connector-mxj-usagenotes-jmx-agent,  Prev: connector-mxj-usagenotes-packaging,  Up: connector-mxj-usagenotes

20.5.6.2 Deploying Connector/MXJ with a pre-configured database
...............................................................

To include a pre-configured/populated database within your
Connector/MXJ JAR file you must create a custom `data_dir.jar' file, as
included within the main `connector-mxj.jar' (Connector/MXJ 5.0.3 or
earlier) or `mysql-connector-mxj-gpl-[ver]-db-files.jar' (Connector/MXJ
5.0.4 or later) file:

  1. First extract the `connector-mxj.jar' or
     `mysql-connector-gpl-[ver]-db-files.jar' file, as outlined in the
     previous section (see *Note connector-mxj-usagenotes-packaging::).

  2. First, create your database and populate the database with the
     information you require in an existing instance of MySQL -
     including Connector/MXJ instances. Data file formats are
     compatible across platforms.

  3. Shutdown the instance of MySQL.

  4. Create a JAR file of the data directory and databases that you
     want to include your Connector/MXJ package. You should include the
     `mysql' database, which includes user authentication information,
     in addition to the specific databases you want to include. For
     example, to create a JAR of the `mysql' and `mxjtest' databases:

          shell> jar -cf ../data_dir.jar mysql mxjtest

  5. For Connector/MXJ 5.0.3 or earlier, copy the `data_dir.jar' file
     into the extracted `connector-mxj.jar' directory, and then create
     an archive for `connector-mxj.jar'.

     For Connector/MXJ 5.0.4 or later, copy the `data_dir.jar' file
     into the extracted `mysql-connector-mxj-gpl-[ver]-db-files.jar'
     directory, and then create an archive for
     `mysql-connector-mxj-db-gpl-[ver]--files.jar'.

Note that if you are create databases using the InnoDB engine, you must
include the `ibdata.*' and `ib_logfile*' files within the
`data_dir.jar' archive.


File: manual.info,  Node: connector-mxj-usagenotes-jmx-agent,  Next: connector-mxj-usagenotes-standard-environment,  Prev: connector-mxj-usagenotes-customdb,  Up: connector-mxj-usagenotes

20.5.6.3 Running within a JMX Agent (custom)
............................................

As a JMX MBean, MySQL Connector/MXJ requires a JMX v1.2 compliant MBean
container, such as JBoss version 4. The MBean will uses the standard
JMX management APIs to present (and allow the setting of) parameters
which are appropriate for that platform.

If you are not using the SUN Reference implementation of the JMX
libraries, you should skip this section. Or, if you are deploying to
JBoss, you also may wish to skip to the next section.

We want to see the MysqldDynamicMBean in action inside of a JMX agent.
In the `com.mysql.management.jmx.sunri' package is a custom JMX agent
with two MBeans:

  1. the MysqldDynamicMBean, and

  2. a com.sun.jdmk.comm.HtmlAdaptorServer, which provides a web
     interface for manipulating the beans inside of a JMX agent.

When this very simple agent is started, it will allow a MySQL database
to be started and stopped with a web browser.

  1. Complete the testing of the platform as above.

        * current JDK, JUnit, Connector/J, MySQL Connector/MXJ

        * this section _requires_ the SUN reference implementation of
          JMX

        * `PATH', `JAVA_HOME', `ANT_HOME', `CLASSPATH'

  2. If not building from source, skip to next step

     rebuild with the "sunri.present"

          ant -Dsunri.present=true dist
          re-run tests:
          java junit.textui.TestRunner com.mysql.management.AllTestsSuite

  3. launch the test agent from the command line:

          java com.mysql.management.jmx.sunri.MysqldTestAgentSunHtmlAdaptor &

  4. from a browser:

          http://localhost:9092/

  5. under MysqldAgent,

          select "name=mysqld"

  6. Observe the MBean View

  7. scroll to the bottom of the screen press the `startMysqld' button

  8. click `Back to MBean View'

  9. scroll to the bottom of the screen press `stopMysqld' button

 10. kill the java process running the Test Agent (jmx server)


File: manual.info,  Node: connector-mxj-usagenotes-standard-environment,  Prev: connector-mxj-usagenotes-jmx-agent,  Up: connector-mxj-usagenotes

20.5.6.4 Deployment in a standard JMX Agent environment (JBoss)
...............................................................

Once there is confidence that the MBean will function on the platform,
deploying the MBean inside of a standard JMX Agent is the next step.
Included are instructions for deploying to JBoss.

  1. Ensure a current version of java development kit (v1.4.x), see
     above.

        * Ensure `JAVA_HOME' is set (JBoss requires `JAVA_HOME')

        * Ensure `JAVA_HOME/bin' is in the `PATH' (You will NOT need to
          set your CLASSPATH, nor will you need any of the jars used in
          the previous tests).

  2. Ensure a current version of JBoss (v4.0RC1 or better)

          http://www.jboss.org/index.html
          select "Downloads"
          select "jboss-4.0.zip"
          pick a mirror
          unzip ~/dload/jboss-4.0.zip
          create a JBOSS_HOME environment variable set to the unzipped directory
          unix only:
          cd $JBOSS_HOME/bin
          chmod +x *.sh

  3. Deploy (copy) the `connector-mxj.jar' to
     `$JBOSS_HOME/server/default/lib'.

  4. Deploy (copy) `mysql-connector-java-3.1.4-beta-bin.jar' to
     `$JBOSS_HOME/server/default/lib'.

  5. Create a `mxjtest.war' directory in
     `$JBOSS_HOME/server/default/deploy'.

  6. Deploy (copy) `index.jsp' to
     `$JBOSS_HOME/server/default/deploy/mxjtest.war'.

  7. Create a `mysqld-service.xml' file in
     `$JBOSS_HOME/server/default/deploy'.

          <?xml version="1.0" encoding="UTF-8"?>
           <server>
            <mbean code="com.mysql.management.jmx.jboss.JBossMysqldDynamicMBean"
               name="mysql:type=service,name=mysqld">
            <attribute name="datadir">/tmp/xxx_data_xxx</attribute>
            <attribute name="autostart">true</attribute>
            </mbean>
           </server>

  8. Start jboss:

        * on unix: `$JBOSS_HOME/bin/run.sh'

        * on windows: `%JBOSS_HOME%\bin\run.bat'

     Be ready: JBoss sends a lot of output to the screen.

  9. When JBoss seems to have stopped sending output to the screen,
     open a web browser to: `http://localhost:8080/jmx-console'

 10. Scroll down to the bottom of the page in the `mysql' section,
     select the bulleted `mysqld' link.

 11. Observe the JMX MBean View page. MySQL should already be running.

 12. (If "autostart=true" was set, you may skip this step.)  Scroll to
     the bottom of the screen. You may press the `Invoke' button to
     stop (or start) MySQL observe `Operation completed successfully
     without a return value.' Click `Back to MBean View'

 13. To confirm MySQL is running, open a web browser to
     `http://localhost:8080/mxjtest/' and you should see that

          SELECT 1

     returned with a result of

          1

 14. Guided by the
     `$JBOSS_HOME/server/default/deploy/mxjtest.war/index.jsp' you will
     be able to use MySQL in your Web Application. There is a `test'
     database and a `root' user (no password) ready to experiment with.
     Try creating a table, inserting some rows, and doing some selects.

 15. Shut down MySQL. MySQL will be stopped automatically when JBoss is
     stopped, or: from the browser, scroll down to the bottom of the
     MBean View press the stop service `Invoke' button to halt the
     service.  Observe `Operation completed successfully without a
     return value.' Using `ps' or `task manager' see that MySQL is no
     longer running

As of 1.0.6-beta version is the ability to have the MBean start the
MySQL database upon start up. Also, we've taken advantage of the JBoss
life-cycle extension methods so that the database will gracefully shut
down when JBoss is shutdown.


File: manual.info,  Node: connector-mxj-support,  Prev: connector-mxj-usagenotes,  Up: connector-mxj

20.5.7 Connector/MXJ Support
----------------------------

* Menu:

* connector-mxj-support-community::  Connector/MXJ Community Support
* connector-mxj-support-bug-report::  How to Report Connector/MXJ Problems
* connector-mxj-support-changelog::  Connector/MXJ Change History

There are a wide variety of options available for obtaining support for
using Connector/MXJ. You should contact the Connector/MXJ community for
help before reporting a potential bug or problem. See *Note
connector-mxj-support-community::.


File: manual.info,  Node: connector-mxj-support-community,  Next: connector-mxj-support-bug-report,  Prev: connector-mxj-support,  Up: connector-mxj-support

20.5.7.1 Connector/MXJ Community Support
........................................

Sun Microsystems, Inc. provides assistance to the user community by
means of a number of mailing lists and web based forums.

You can find help and support through the MySQL and Java
(http://lists.mysql.com/java) mailing list.

For information about subscribing to MySQL mailing lists or to browse
list archives, visit `http://lists.mysql.com/'. See *Note
mailing-lists::.

Community support from experienced users is also available through the
MyODBC Forum (http://forums.mysql.com/list.php?39). You may also find
help from other users in the other MySQL Forums, located at
`http://forums.mysql.com'. See *Note forums::.


File: manual.info,  Node: connector-mxj-support-bug-report,  Next: connector-mxj-support-changelog,  Prev: connector-mxj-support-community,  Up: connector-mxj-support

20.5.7.2 How to Report Connector/MXJ Problems
.............................................

If you encounter difficulties or problems with Connector/MXJ, contact
the Connector/MXJ community *Note connector-mxj-support-community::.

If reporting a problem, you should ideally include the following
information with the email:

   * Operating system and version

   * Connector/MXJ version

   * MySQL server version

   * Copies of error messages or other unexpected output

   * Simple reproducible sample

Remember that the more information you can supply to us, the more
likely it is that we can fix the problem.

If you believe the problem to be a bug, then you must report the bug
through `http://bugs.mysql.com/'.


File: manual.info,  Node: connector-mxj-support-changelog,  Prev: connector-mxj-support-bug-report,  Up: connector-mxj-support

20.5.7.3 Connector/MXJ Change History
.....................................

The Connector/MXJ Change History (Changelog) is located with the main
Changelog for MySQL. See *Note news-connector-mxj::.


File: manual.info,  Node: connector-cpp,  Next: connector-c,  Prev: connector-mxj,  Up: connectors-apis

20.6 MySQL Connector/C++
========================

* Menu:

* connector-cpp-installation-binary::  MySQL Connector/C++ Binary Installation
* connector-cpp-installation-source::  MySQL Connector/C++ Source Installation
* connector-cpp-apps-windows-visual-studio::  MySQL Connector/C++ Building Windows applications with Microsoft Visual Studio
* connector-cpp-apps-linux-netbeans::  MySQL Connector/C++ Building Linux applications with NetBeans
* connector-cpp-getting-started-examples::  MySQL Connector/C++ Getting Started: Usage Examples
* connector-cpp-debug-tracing::  MySQL Connector/C++ Debug Tracing
* connector-cpp-references::     MySQL Connector/C++ References
* connector-cpp-bugs::           MySQL Connector/C++ Known Bugs and Issues
* connector-cpp-requests::       MySQL Connector/C++ Feature requests
* connector-cpp-support::        MySQL Connector/C++ Support
* connector-cpp-faq::            MySQL Connector/C++ FAQ

*Caution*:

Please note, official support is not available for the beta version of
MySQL Connector/C++.

MySQL Connector/C++ is a MySQL database connector for C++.

The MySQL Connector/C++ is licensed under the terms of the GPL, like
most MySQL Connectors. There are special exceptions to the terms and
conditions of the GPL as it is applied to this software, see FLOSS
License Exception. If you need a non-GPL license for commercial
distribution please contact us.

The MySQL Connector/C++ is compatible with the JDBC 4.0 API. However,
MySQL Connector/C++ does not implement all of the JDBC 4.0 API. The
MySQL Connector/C++ current version features the following classes:

   * Connection

   * DatabaseMetaData

   * Driver

   * PreparedStatement

   * ResultSet

   * ResultSetMetaData

   * Savepoint

   * Statement

The JDBC 4.0 API defines approximately 450 methods for the above
mentioned classes. MySQL Connector/C++ implements around 80% of these
and makes them available in the preview release.

The Beta release has been successfully compiled and tested on the
following platforms:

*AIX*

   * 5.2 (PPC32, PPC64)

   * 5.3 (PPC32, PPC64)

*FreeBSD*

   * 6.0 (x86, x86_64)

*HPUX*

   * 11.11 (PA-RISC 32bit, PA-RISC 64bit)

*Linux*

   * Debian 3.1 (PPC32, x86)

   * FC4 (x86)

   * RHEL 3 (ia64, x86, x86_64)

   * RHEL 4 (ia64, x86, x86_64)

   * RHEL 5 (ia64, x86, x86_64)

   * SLES 9 (ia64, x86, x86_64)

   * SLES 10 (ia64, x86_64)

   * SuSE 10.3, (x86_64)

   * Ubuntu 8.04 (x86)

   * Ubuntu 8.10 (x86_64)

*Mac*

   * MacOSX 10.3 (PPC32, PPC64)

   * MacOSX 10.4 (PPC32, PPC64, x86)

   * MacOSX 10.5 (PPC32, PPC64, x86, x86_64)

*SunOS*

   * Solaris 8 (SPARC32, SPARC64, x86)

   * Solaris 9 (SPARC32, SPARC64, x86)

   * Solaris 10 (SPARC32, SPARC64, x86, x86_64)

*Windows*

   * XP Professional (32bit)

   * 2003 (64bit)

Future versions will run on all platforms supported by the MySQL Server.

*Note*:

MySQL Connector/C++ supports MySQL 5.1 and later.

*Note*:

MySQL Connector/C++ supports only Microsoft Visual Studio 2003 and
above on Windows.

*MySQL Connector/C++ Download*

You can download the source code for the MySQL Connector/C++ preview
release at the download site
(http://downloads.mysql.com/forge/connector_cpp_preview).

*MySQL Connector/C++ Source repository*

The latest development version is also available through Launchpad
(https://launchpad.net/mysql-connector-cpp).

Bazaar is used for the MySQL Connector/C++ code repository. You can
check out the source code using the `bzr' command line tool:

     shell> bzr branch lp:~mysql/mysql-connector-cpp/trunk .

The source of the 1.0.3alpha release is available from the following
branch:

     shell> bzr branch lp:~andrey-mysql/mysql-connector-cpp/v1_0_3

The source of the 1.0.2alpha release is available from the following
branch:

     shell> bzr branch lp:~andrey-mysql/mysql-connector-cpp/v1_0_2

The source of the 1.0.1alpha release is available from the following
branch:

     shell> bzr branch lp:~andrey-mysql/mysql-connector-cpp/v1_0_1

*Binary distributions*

Starting with 1.0.4 Beta, binary distributions will be made available
in addition to source code releases. The releases available are shown
below.

Microsoft Windows platform:

   * Without installer, a Zip file

   * MSI installer package

Other platforms:

   * Compressed GNU TAR archive (tar.gz)

*Note*:

Note that source packages are available for all platforms in the
Compressed GNU TAR archive (tar.gz) format.

*MySQL Connector/C++ Advantages*

Using MySQL Connector/C++ instead of the MySQL C API (MySQL Client
Library) offers the following advantages for C++ users:

   * Convenience of pure C++, no C function calls required

   * Supports an industry standard API, JDBC 4.0

   * Supports the object-oriented programming paradigm

   * Reduces development time

   * MySQL Connector/C++ is licensed under the GPL with the FLOSS
     License Exception

   * MySQL Connector/C++ is available under a commercial license upon
     request

*MySQL Connector/C++ Status*

MySQL Connector/C++ is available as a development preview version. We
kindly ask users and developers to try it out and provide us with
feedback. We do not encourage you to use it in production environments.

Note that MySQL Workbench is successfully using MySQL Connector/C++.

*Note*:

Sun Microsystems does not provide formal support for MySQL
Connector/C++.

If you have any queries please *Note contact us: connector-cpp-support.


File: manual.info,  Node: connector-cpp-installation-binary,  Next: connector-cpp-installation-source,  Prev: connector-cpp,  Up: connector-cpp

20.6.1 MySQL Connector/C++ Binary Installation
----------------------------------------------

*Caution*:

Please note, official support is not available for the beta version of
MySQL Connector/C++.

*Caution*:

One problem that can occur is when the tools you use to build your
application are not compatible with the tools used to build the binary
versions of MySQL Connector/C++. Ideally you need to build your
application with the same tools that were used to build the MySQL
Connector/C++ binaries. To help with this the following resources are
provided.

All distributions contain a `README' file, which contains
platform-specific notes. At the end of the `README' file contained in
the binary distribution you will find the settings used to build the
binaries. If you experience build-related issues on a platform, it may
help to check the settings used on the platform to build the binary.

For your convenience the same information, but more frequently updated,
can be found on the MySQL Forge site
(http://forge.mysql.com/wiki/Connector_C%2B%2B_Binary_Builds).

A better solution is to build your MySQL Connector/C++ libraries from
the source code, using the same tools that you use for building your
application. This ensures compatibility.

*Archive Package*

Unpack the archive into an appropriate directory. If you plan to use a
dynamically linked version of MySQL Connector/C++, make sure that your
system can reference the MySQL Client Library. Consult your operating
system documentation on how do modify and expand the search path for
libraries. In case you cannot modify the library search path it may
help to copy your application, the MySQL Connector/C++ library and the
MySQL Client Library into the same directory. Most systems search for
libraries in the current directory.

*Windows MSI Installer*

Windows users can choose between two binary packages:

  1. Without installer (unzip in C:\)

  2. Windows MSI Installer (x86)

Using the MSI Installer may be the easiest solution. Running the MSI
Installer does not require any administrative permissions as it simply
copies files.

FIGURE GOES HERE: Windows Installer Welcome Screen

FIGURE GOES HERE: Windows Installer Overview Screen

The `Typical' installation consists of all required header files and
the Release libraries. The only available `Custom' installation option
allows you to install additional Debug versions of the connector
libraries.

FIGURE GOES HERE: Windows Installer Custom Setup Screen


File: manual.info,  Node: connector-cpp-installation-source,  Next: connector-cpp-apps-windows-visual-studio,  Prev: connector-cpp-installation-binary,  Up: connector-cpp

20.6.2 MySQL Connector/C++ Source Installation
----------------------------------------------

* Menu:

* connector-cpp-installation-source-unix::  Building source on Unix, Solaris and Mac OS X
* connector-cpp-installation-source-windows::  Building on Windows

*Caution*:

Please note, official support is not available for the beta version of
MySQL Connector/C++.

The MySQL Connector/C++ is based on the MySQL Client Library (MySQL C
API).  MySQL Connector/C++ is linked against the MySQL Client Library.
You need to have the MySQL Client Library installed in order to compile
MySQL Connector/C++.

You also need to have the cross-platform build tool CMake 2.4, or
newer, and GLib 2.2.3 or newer installed. Check the README file
included with the distribution for platform specific notes on building
for Windows and SunOS.

Typically the MySQL Client Library is installed when the MySQL Server
is installed. However, check your operating system documentation for
other installation options.


File: manual.info,  Node: connector-cpp-installation-source-unix,  Next: connector-cpp-installation-source-windows,  Prev: connector-cpp-installation-source,  Up: connector-cpp-installation-source

20.6.2.1 Building source on Unix, Solaris and Mac OS X
......................................................

  1. Run CMake to build a Makefile:

          shell> me@host:/path/to/mysql-connector-cpp> cmake .
          -- Check for working C compiler: /usr/local/bin/gcc
          -- Check for working C compiler: /usr/local/bin/gcc -- works
          [...]
          -- Generating done
          -- Build files have been written to: /path/to/mysql-connector-cpp/

     On non-Windows systems, CMake first checks to see if the CMake
     variable `MYSQL_CONFIG_EXECUTABLE' is set. If it is not found
     CMake will try to locate `mysql_config' in the default locations.

     If you have any problems with the configure process please check
     the troubleshooting instructions below.

  2. Use make to build the libraries. First make sure you have a clean
     build:

          shell> me@host:/path/to/mysql-connector-cpp> make clean

     Then build the connector:

          me@host:/path/to/mysql-connector-cpp> make
          [  1%] Building CXX object »
          driver/CMakeFiles/mysqlcppconn.dir/mysql_connection.o
          [  3%] Building CXX object »
          driver/CMakeFiles/mysqlcppconn.dir/mysql_constructed_resultset.o
          [...]
          [100%] Building CXX object examples/CMakeFiles/statement.dir/statement.o
          Linking CXX executable statement

     If all goes well, you will find the MySQL Connector/C++ library in
     `/path/to/cppconn/libmysqlcppconn.so'.

  3. Finally make sure the header and library files are installed to
     their correct locations:

          make install

     Unless you have changed this in the configuration step, the header
     files will be copied to the directory `/usr/local/include'. The
     header files copied are `mysql_connection.h' and `mysql_driver.h'.

     Again, unless you have specified otherwise, the library files will
     be copied to `/usr/local/lib'.  The files copied are
     `libmysqlcppcon.so', the dynamic library, and
     `libmysqlcppconn-static.a', the static library.

If you encounter any errors, please first carry out the checks shown
below:

  1. CMake options: MySQL installation path, debug version and more

     In case of configure and/or compile problems check the list of
     CMake options:

          shell> me@host:/path/to/mysql-connector-cpp> cmake -L
          [...]
          CMAKE_BACKWARDS_COMPATIBILITY:STRING=2.4
          CMAKE_BUILD_TYPE:STRING=
          CMAKE_INSTALL_PREFIX:PATH=/usr/local
          EXECUTABLE_OUTPUT_PATH:PATH=
          LIBRARY_OUTPUT_PATH:PATH=
          MYSQLCPPCONN_GCOV_ENABLE:BOOL=0
          MYSQLCPPCONN_TRACE_ENABLE:BOOL=0
          MYSQL_CONFIG_EXECUTABLE:FILEPATH=/usr/bin/mysql_config

     For example, if your MySQL Server installation path is not
     `/usr/local/mysql' and you want to build a debug version of the
     MySQL Connector/C++ use:

          shell> me@host:/path/to/mysql-connector-cpp> cmake »
          -D CMAKE_BUILD_TYPE:STRING=Debug »
          -D MYSQL_CONFIG_EXECUTABLE=/path/to/my/mysql/server/bin/mysql_config .

  2. Verify your settings with `cmake `-L'':

          shell> me@host:/path/to/mysql-connector-cpp> cmake -L
          [...]
          CMAKE_BACKWARDS_COMPATIBILITY:STRING=2.4
          CMAKE_BUILD_TYPE:STRING=
          CMAKE_INSTALL_PREFIX:PATH=/usr/local
          EXECUTABLE_OUTPUT_PATH:PATH=
          LIBRARY_OUTPUT_PATH:PATH=
          MYSQLCPPCONN_GCOV_ENABLE:BOOL=0
          MYSQLCPPCONN_TRACE_ENABLE:BOOL=0
          MYSQL_CONFIG_EXECUTABLE=/path/to/my/mysql/server/bin/mysql_config

     Proceed by carrying out a `make clean' command followed by a
     `make' command, as described above.


File: manual.info,  Node: connector-cpp-installation-source-windows,  Prev: connector-cpp-installation-source-unix,  Up: connector-cpp-installation-source

20.6.2.2 Building on Windows
............................

*Note*:

Please note the only compiler formally supported for Windows is
Microsoft Visual Studio 2003 and above.

The basic steps for building the connector on Windows are the same as
for Unix. It is important to use CMake 2.6.2 or newer to generate build
files for your compiler and to invoke the compiler.

*Note*:

On Windows, `mysql_config' is not present, so CMake will attempt to
retrieve the location of MySQL from the environment variable
`$ENV{MYSQL_DIR}'. If `MYSQL_DIR' is not set, CMake will then proceed
to check for MySQL in the following locations:
`$ENV{ProgramFiles}/MySQL/*/include', and
`$ENV{SystemDrive}/MySQL/*/include'.

CMake makes it easy for you to try out other compilers. However, you
may experience compile warnings, compile errors or linking issues not
detected by Visual Studio. Patches are gratefully accepted to fix
issues with other compilers.

Consult the CMake manual or check `cmake --help' to find out which
build systems are supported by your CMake version:

     C:\>cmake --help
     cmake version 2.6-patch 2
     Usage
     [...]
     Generators

     The following generators are available on this platform:
       Borland Makefiles           = Generates Borland makefiles.
       MSYS Makefiles              = Generates MSYS makefiles.
       MinGW Makefiles             = Generates a make file for use with
                                     mingw32-make.
       NMake Makefiles             = Generates NMake makefiles.
       Unix Makefiles              = Generates standard UNIX makefiles.
       Visual Studio 6             = Generates Visual Studio 6 project files.
       Visual Studio 7             = Generates Visual Studio .NET 2002 project
                                     files.
       Visual Studio 7 .NET 2003   = Generates Visual Studio .NET 2003 project
                                     files.
       Visual Studio 8 2005        = Generates Visual Studio .NET 2005 project
                                     files.
       Visual Studio 8 2005 Win64  = Generates Visual Studio .NET 2005 Win64
                                     project files.
       Visual Studio 9 2008        = Generates Visual Studio 9 2008 project fil
       Visual Studio 9 2008 Win64  = Generates Visual Studio 9 2008 Win64 proje
                                     files.
     [...]

It is likely that your CMake binary will support more compilers, known
by CMake as _generators_, than supported by MySQL Connector/C++. We
have built the connector using the following generators:

   * Microsoft Visual Studio 8 (Visual Studio 2005)

   * Microsoft Visual Studio 9 (Visual Studio 2008, Visual Studio 2008
     Express)

   * NMake

Please see the building instructions for Unix, Solaris and Mac OS X for
troubleshooting and configuration hints.

The steps to build the connector are given below:

  1. Run CMake to generate build files for your _generator_:

     *Visual Studio*

           C:\path_to_mysql_cpp>cmake -G "Visual Studio 9 2008"
          -- Check for working C compiler: cl
          -- Check for working C compiler: cl -- works
          -- Detecting C compiler ABI info
          -- Detecting C compiler ABI info - done
          -- Check for working CXX compiler: cl
          -- Check for working CXX compiler: cl -- works
          -- Detecting CXX compiler ABI info
          -- Detecting CXX compiler ABI info - done
          -- ENV{MYSQL_DIR} =
          -- MySQL Include dir: C:/Programme/MySQL/MySQL Server 5.1/include
          -- MySQL Library    : C:/Progams/MySQL/MySQL Server 5.1/lib/opt/mysqlclient.lib
          -- MySQL Library dir: C:/Progams/MySQL/MySQL Server 5.1/lib/opt
          -- MySQL CFLAGS:
          -- MySQL Link flags:
          -- MySQL Include dir: C:/Progams/MySQL/MySQL Server 5.1/include
          -- MySQL Library dir: C:/Progams/MySQL/MySQL Server 5.1/lib/opt
          -- MySQL CFLAGS:
          -- MySQL Link flags:
          -- Configuring cppconn
          -- Configuring test cases
          -- Looking for isinf
          -- Looking for isinf - not found
          -- Looking for isinf
          -- Looking for isinf - not found.
          -- Looking for finite
          -- Looking for finite - not found.
          -- Configuring C/J junit tests port
          -- Configuring examples
          -- Configuring done
          -- Generating done
          -- Build files have been written to: C:\path_to_mysql_cpp
          C:\path_to_mysql_cpp>dir *.sln *.vcproj
          [...]
          19.11.2008  12:16            23.332 MYSQLCPPCONN.sln
          [...]
          19.11.2008  12:16            27.564 ALL_BUILD.vcproj
          19.11.2008  12:16            27.869 INSTALL.vcproj
          19.11.2008  12:16            28.073 PACKAGE.vcproj
          19.11.2008  12:16            27.495 ZERO_CHECK.vcproj

     *NMake*

           C:\path_to_mysql_cpp>cmake -G "NMake Makefiles"
          -- The C compiler identification is MSVC
          -- The CXX compiler identification is MSVC
          [...]
          -- Build files have been written to: C:\path_to_mysql_cpp

  2. Use your compiler to build MySQL Connector/C++

     *Visual Studio - GUI*

     Open the newly generated project files in the Visual Studio GUI or
     use a Visual Studio command line to build the driver.  The project
     files contain a variety of different configurations. Among them
     debug and non-debug versions.

     *Visual Studio - NMake*

          C:\path_to_mysql_cpp>nmake

          Microsoft (R) Program Maintenance Utility Version 9.00.30729.01
          Copyright (C) Microsoft Corporation.  All rights reserved.

          Scanning dependencies of target mysqlcppconn
          [  2%] Building CXX object driver/CMakeFiles/mysqlcppconn.dir/mysql_connection.obj
          mysql_connection.cpp
          [...]
          Linking CXX executable statement.exe
          [100%] Built target statement


File: manual.info,  Node: connector-cpp-apps-windows-visual-studio,  Next: connector-cpp-apps-linux-netbeans,  Prev: connector-cpp-installation-source,  Up: connector-cpp

20.6.3 MySQL Connector/C++ Building Windows applications with Microsoft Visual Studio
-------------------------------------------------------------------------------------

MySQL Connector/C++ is available as a static or dynamic library to use
with your application. This section looks at how to link the library to
your application.

*Note*:

To avoid potential crashes the build configuration of MySQL
Connector/C++ should match the build configuration of the application
using it. For example, do not use the release build of MySQL
Connector/C++ with a debug build of the client application.

*Static library*

The MySQL Connector/C++ static library file is
`mysqlcppconn-static.lib'. This needs to be statically linked with your
application. You also need to link against the files `libmysql.dll' and
`libmysql.lib'. Once linking has been successfully completed, the
application will require access to `libmysql.dll' at run time.

*Dynamic library*

The MySQL Connector/C++ dynamic library file is `mysqlcppconn.dll'. In
order to build your client application you need to link it with the file
`mysqlcppconn.lib'. At run time the application will require access to
the files `mysqlcppconn.dll' and `libmysql.dll'.

*Building a MySQL Connector/C++ application with Microsoft Visual
Studio*

Initially, the procedure for building an application to use either the
static or dynamic library is the same. You then carry out some
additional steps depending on whether you want to build your
application to use the static or dynamic library.

  1. Select `File', `New', `Project' from the main menu.

     FIGURE GOES HERE: Creating a new project

  2. In the wizard select `Visual C++', `Win32'. From `Visual Studio
     Installed Templates' select the application type `Win32 Console
     Application'. Enter a name for the application, and then click
     `OK', to move to the Win32 Application Wizard.

     FIGURE GOES HERE: The New Project dialog box

  3. In the Win32 Application Wizard, click on `Application Settings'
     and ensure the defaults are selected. The radio button `Console
     application', and the checkbox `Precompiled headers' will be
     selected. Click `Finish' to close the wizard.

     FIGURE GOES HERE: The Win32 Application Wizard

  4. From the drop down list box on the toolbar, change from the
     default `Debug' build to the `Release' build.

     FIGURE GOES HERE: Selecting the Release build

  5. From the main menu select `Project', `Properties'. This can also
     be accessed using the hot key `ALT' + `F7'.

     FIGURE GOES HERE: Selecting Project Properties from the main menu

  6. Under `Configuration Properties', open the tree view.

  7. Select `C++', `General' in the tree view.

     FIGURE GOES HERE: Setting properties

  8. You now need to ensure that Visual Studio can find the MySQL
     include directory. This directory includes header files that can
     optionally be installed when installing MySQL Server.

     FIGURE GOES HERE: MySQL include directory

  9. Then in the `Additional Include Directories' text field, add the
     MySQL `include/' directory.

     FIGURE GOES HERE: Select Directory dialog

 10. You will also need to set the location of additional libraries
     that Visual Studio will need in order to build the application.
     These are located in the MySQL `lib/opt' directory, a
     sub-directory of the MySQL Server installation directory.

     FIGURE GOES HERE: Typical contents of MySQL lib/opt directory

 11. In the tree view open `Linker', `General', `Additional Library
     Directories'.

     FIGURE GOES HERE: Additional Library Directories

 12. Add the `lib/opt' directory into the `Additional Library
     Directories' text field. This allows the library file
     `libmysql.lib' to be found.

     FIGURE GOES HERE: Additional Library Directories dialog

The remaining steps depend on whether you are building an application
to use the MySQL Connector/C++ static or dynamic library. If you are
building your application to use the dynamic library go here. If you
are building your application to use the static library, carry out the
following steps:

  1. Then open `Linker', `Input', `Additional Dependencies'.

     FIGURE GOES HERE:

  2. Enter `mysqlcppconn-static.lib' and `libmysql.lib'.

     FIGURE GOES HERE: Adding additional dependencies

  3. By default `CPPCONN_PUBLIC_FUNC' is defined to declare functions
     to be compatible with an application that calls a DLL. If building
     an application to call the static library, you must ensure that
     function prototypes are compatible with this. In this case
     `CPPCONN_PUBLIC_FUNC' needs to be defined to be an empty string,
     so that functions are declared with the correct prototype.

     In the `Project', `Properties' tree view, under `C++',
     `Preprocessor', enter `CPPCONN_PUBLIC_FUNC=' into the
     `Preprocessor Definitions' text field.

     FIGURE GOES HERE: Setting the CPPCONN_PUBLIC_FUNC define

     *Note*:

     Make sure you enter `CPPCONN_PUBLIC_FUNC=' and not
     `CPPCONN_PUBLIC_FUNC', as it needs to be defined as an empty
     string.

If building an application to use the MySQL Connector/C++ dynamically
linked library carry out these steps:

  1. Under `Linker', `Input', add `mysqlcppconn.lib' into the
     `Additional Dependencies' text field.

  2. The application will need to access the MySQL Connector/C++
     Dynamic Linked Library at run time. Therefore, `mysqlcppconn.dll'
     needs to be in the same directory as the application executable,
     or somewhere on the system's path.

     Copy `mysqlcppconn.dll' to the same directory as the application.
     Alternatively, extend the `PATH' environment variable using `SET
     PATH=%PATH%;C:\path\to\cpp'.  Alternatively, you can copy
     `mysqlcppconn.dll' to the Windows installation Directory, typically
     `c:\windows'.


File: manual.info,  Node: connector-cpp-apps-linux-netbeans,  Next: connector-cpp-getting-started-examples,  Prev: connector-cpp-apps-windows-visual-studio,  Up: connector-cpp

20.6.4 MySQL Connector/C++ Building Linux applications with NetBeans
--------------------------------------------------------------------

This section describes how you can build MySQL Connector/C++
applications for Linux using the NetBeans IDE.

FIGURE GOES HERE: The NetBeans IDE

*Note*:

To avoid potential crashes the build configuration of MySQL
Connector/C++ should match the build configuration of the application
using it. For example, do not use the release build of MySQL
Connector/C++ with a debug build of the client application.

  1. The first step of building your application is to create a new
     project. Select `File', `New Project'. Choose a `C/C++
     Application' and click `Next'.

  2. Give the project a name and click `Finish'. A new project is
     created.

  3. In the `Projects' tab, right-click on `Source Files' and select
     `New', then `Main C++ File...'.

  4. Change the filename, or simply select the defaults and click
     `Finish' to add the new file to the project.

  5. You now need to add some working code to you main source file.
     Explore your MySQL Connector/C++ installation and navigate to the
     `examples' directory.

  6. Select a suitable example such as `standalone_example_docs1.cpp'.
     Copy all the code in this file, and use it to replace the code in
     your existing main source file. Amend the code to reflect the
     connection properties required for your test database. You now
     have a working example that will access a MySQL database using
     MySQL Connector/C++.

  7. You will notice that at this point NetBeans is showing some errors
     in the source code. This is because you need to direct NetBeans to
     the necessary header files that need to be included. Select
     `File', `Project Properties' from the main menu.

  8. In the `Categories:' tree view panel, navigate to `Build', `C++
     Compiler'.

  9. In the `General' panel, select `Include Directories'.

 10. Click the `...' button.

 11. Click `Add' and then navigate to the directory where the MySQL
     Connector/C++ header files are located. This will be
     `/usr/local/include' unless you have installed the files to a
     different location. Click `Select'. Click `OK'.

     FIGURE GOES HERE: Setting the header include directory

 12. Click `OK' again to close the `Project Properties' dialog.

At this point you have created a NetBeans project, containing a single
C++ source file. You have also ensured that the necessary include files
are accessible. Before continuing, you need to decide whether your
project is to use the MySQL Connector/C++ static or dynamic library.
The project settings are slightly different in each case, as you need
to link against a different library.

*Using the static library*

If you intend to use the static library you will need to link against
two library files, `libmysqlcppconn-static.a' and `libmysqlclient.a'.
The locations of the files will depend on your setup, but typically the
former will be found in `/usr/local/lib' and the latter in `/usr/lib'.
Note the file `libmysqlclient.a' is not part of MySQL Connector/C++, but
is the MySQL Client Library file distributed with MySQL Server.
Remember, the MySQL Client Library is an optional component as part of
the MySQL Server installation process. Note the MySQL Client Library is
also available as part of the new MySQL Connector/C distribution.

  1. The first step is to set the project to link the necessary library
     files. Select `File', `Project Properties' from the main menu.

  2. In the `Categores:' tree view navigate to `Linker'.

  3. In the `General' panel select `Additional Library Directories'.
     Click the `...' button.

  4. Select and add the `/usr/lib' and `/usr/local/lib' directories.

  5. In the same panel add the two library files required for static
     linking as discussed earlier. The properties panel should then
     look similar to the following screenshot:

     FIGURE GOES HERE: Setting the static library directories and file
     names

  6. Click `OK' to close the `Project Properties' dialog.

*Using the dynamic library*

If you require your application to use the MySQL Connector/C++ dynamic
library, you simply need to link your project with a single library
file, `libmysqlcppconn.so'. The location of this file will depend on
how you configured your installation of MySQL Connector/C++, but will
typically be `/usr/local/lib'.

  1. The first step is to set the project to link the the necessary
     library file. Select `File', `Project Properties' from the main
     menu.

  2. In the `Categories:' tree view navigate to `Linker'.

  3. In the `General' panel select `Additional Library Directories'.
     Click the `...' button.

  4. Select and add the `/usr/local/lib' directories.

  5. In the same panel add the library file required for static linking
     as discussed earlier. The properties panel should then look
     similar to the following screenshot:

     FIGURE GOES HERE: Setting the dynamic library directory and file
     name

  6. Click OK to close the Project Properties dialog.

Having configured your project you can build it by selecting `Run',
`Build Main Project' from the main menu. You can then run the project
using `Run', `Run Main Project'.

On running the application you should see a screen similar to the
following (this is actually the static version of the application
shown):

FIGURE GOES HERE: The example application running

*Note*:

Note the above settings and procedures were carried out for the default
`Debug' configuration. If you want to create a `Release' configuration
you will need to select that configuration before setting the Project
Properties.


File: manual.info,  Node: connector-cpp-getting-started-examples,  Next: connector-cpp-debug-tracing,  Prev: connector-cpp-apps-linux-netbeans,  Up: connector-cpp

20.6.5 MySQL Connector/C++ Getting Started: Usage Examples
----------------------------------------------------------

* Menu:

* connector-cpp-examples-connecting::  MySQL Connector/C++ Connecting to MySQL
* connector-cpp-examples-query::  MySQL Connector/C++ Running a simple query
* connector-cpp-examples-results::  MySQL Connector/C++ Fetching results
* connector-cpp-examples-prepared-statements::  MySQL Connector/C++ Using Prepared Statements
* connector-cpp-examples-complete-example-1::  MySQL Connector/C++ Complete Example 1
* connector-cpp-examples-complete-example-2::  MySQL Connector/C++ Complete Example 2

*Caution*:

Please note, official support is not available for the beta version of
MySQL Connector/C++.

The download package contains usage examples in the directory
`examples/'. The examples explain the basic usage of the following
classes:

   * Connection

   * Driver

   * PreparedStatement

   * ResultSet

   * ResultSetMetaData

   * Statement

The examples cover:

   * Using the Driver class to connect to MySQL

   * Creating tables, inserting rows, fetching rows using (simple)
     statements

   * Creating tables, inserting rows, fetching rows using prepared
     statements

   * Hints for working around prepared statement limitations

   * Accessing result set meta data

The examples in this document are only code snippets. The code snippets
provide a brief overview on the API. They are not complete programs.
Please check the `examples/' directory of your MySQL Connector/C++
installation for complete programs.  Please also read the `README' file
in the `examples/' directory. Note to test the example code you will
first need to edit the `examples.h' file in the `examples/' directory,
to add your connection information. Then simply rebuild the code by
issuing a `make' command.

The examples in the `examples/' directory include:

   * `examples/connect.cpp':

     How to create a connection, insert data into MySQL and handle
     exceptions.

   * `examples/connection_meta_schemaobj.cpp':

     How to obtain meta data associated with a connection object, for
     example, a list of tables, databases, MySQL version, connector
     version.

   * `examples/debug.cpp':

     How to activate and deactivate the MySQL Connector/C++ debug
     protocol.

   * `examples/exceptions.cpp':

     A closer look at the exceptions thrown by the connector and how to
     fetch error information.

   * `examples/prepared_statements.cpp':

     How to run Prepared Statements including an example how to handle
     SQL commands that cannot be prepared by the MySQL Server.

   * `examples/resultset.cpp':

     How to fetch data and iterate over the result set (cursor).

   * `examples/resultset_meta.cpp':

     How to obtain meta data associated with a result set, for example,
     number of columns and column types.

   * `examples/resultset_types.cpp':

     Result sets returned from meta data methods - this is more a test
     than much of an example.

   * `examples/standalone_example.cpp':

     Simple standalone program not integrated into regular CMake builds.

   * `examples/statements.cpp':

     How to run SQL commands without using Prepared Statements.

   * `examples/cpp_trace_analyzer.cpp':

     This example shows how to filter the output of the *Note debug
     trace: connector-cpp-debug-tracing. Please see the inline comments
     for further documentation. This script is unsupported.


File: manual.info,  Node: connector-cpp-examples-connecting,  Next: connector-cpp-examples-query,  Prev: connector-cpp-getting-started-examples,  Up: connector-cpp-getting-started-examples

20.6.5.1 MySQL Connector/C++ Connecting to MySQL
................................................

A connection to MySQL is established by retrieving an instance of
sql::Connection from a sql::mysql::MySQL_Driver object. A
sql::mysql::MySQL_Driver object is returned by
sql::mysql::MySQL_Driver::get_mysql_driver_instance().

     sql::mysql::MySQL_Driver *driver;
     sql::Connection *con;

     driver = sql::mysql::MySQL_Driver::get_mysql_driver_instance();
     con = driver->connect("tcp://127.0.0.1:3306", "user", "password");

     delete con;

Make sure that you free the sql::Connection object as soon as you do
not need it any more. But do not explicitly free the connector object!


File: manual.info,  Node: connector-cpp-examples-query,  Next: connector-cpp-examples-results,  Prev: connector-cpp-examples-connecting,  Up: connector-cpp-getting-started-examples

20.6.5.2 MySQL Connector/C++ Running a simple query
...................................................

For running simple queries you can use the methods
sql::Statement::execute(), sql::Statement::executeQuery() and
sql::Statement::executeUpdate(). The method sql::Statement::execute()
should be used if your query does not return a result set or if your
query returns more than one result set. See the `examples/' directory
for more on this.

     sql::mysql::MySQL_Driver *driver;
     sql::Connection *con;
     sql::Statement *stmt

     driver = sql::mysql::get_mysql_driver_instance();
     con = driver->connect("tcp://127.0.0.1:3306", "user", "password");

     stmt = con->createStatement();
     stmt->execute("USE " EXAMPLE_DB);
     stmt->execute("DROP TABLE IF EXISTS test");
     stmt->execute("CREATE TABLE test(id INT, label CHAR(1))");
     stmt->execute("INSERT INTO test(id, label) VALUES (1, 'a')");

     delete stmt;
     delete con;

Note that you have to free sql::Statement and sql::Connection objects
explicitly using delete.


File: manual.info,  Node: connector-cpp-examples-results,  Next: connector-cpp-examples-prepared-statements,  Prev: connector-cpp-examples-query,  Up: connector-cpp-getting-started-examples

20.6.5.3 MySQL Connector/C++ Fetching results
.............................................

The API for fetching result sets is identical for (simple) statments
and prepared statements. If your query returns one result set you
should use sql::Statement::executeQuery() or
sql::PreparedStatement::executeQuery() to run your query. Both methods
return sql::ResultSet objects. The preview version does buffer all
result sets on the client to support cursors.

     // ...
     sql::Connection *con;
     sql::Statement *stmt
     sql::ResultSet  *res;
     // ...
     stmt = con->createStatement();
     // ...

     res = stmt->executeQuery("SELECT id, label FROM test ORDER BY id ASC");
     while (res->next()) {
       // You can use either numeric offsets...
       cout << "id = " <&;t; res->getInt(0);
       // ... or column names for accessing results. »
         The latter is recommended.
       cout << ", label = '" << »
         res->getString("label") << "'" << endl;
     }

     delete res;
     delete stmt;
     delete con;

Note that you have to free sql::Statement, sql::Connection and
sql::ResultSet objects explicitly using delete.

The usage of cursors is demonstrated in the examples contained in the
download package.


File: manual.info,  Node: connector-cpp-examples-prepared-statements,  Next: connector-cpp-examples-complete-example-1,  Prev: connector-cpp-examples-results,  Up: connector-cpp-getting-started-examples

20.6.5.4 MySQL Connector/C++ Using Prepared Statements
......................................................

If you are not familiar with Prepared Statements on MySQL have an extra
look at the source code comments and explanations in the file
`examples/prepared_statement.cpp'.

sql::PreparedStatement is created by passing a SQL query to
sql::Connection::prepareStatement(). As sql::PreparedStatement is
derived from sql::Statement, you will feel familiar with the API once
you have learned how to use (simple) statements (sql::Statement). For
example, the syntax for fetching results is identical.

     // ...
     sql::Connection	*con;
     sql::PreparedStatement	*prep_stmt
     // ...

     prep_stmt = con->prepareStatement("INSERT INTO test(id, label) VALUES (?, ?)");

     prep_stmt->setInt(1, 1);
     prep_stmt->setString(2, "a");
     prep_stmt->execute();

     prep_stmt->setInt(1, 2);
     prep_stmt->setString(2, "b");
     prep_stmt->execute();

     delete prep_stmt;
     delete con;

As usual, you have to free sql::PreparedStatement and sql::Connection
objects explicitly.


File: manual.info,  Node: connector-cpp-examples-complete-example-1,  Next: connector-cpp-examples-complete-example-2,  Prev: connector-cpp-examples-prepared-statements,  Up: connector-cpp-getting-started-examples

20.6.5.5 MySQL Connector/C++ Complete Example 1
...............................................

The following code shows a complete example of how to use MySQL
Connector/C++:

     /* Copyright 2008 Sun Microsystems, Inc.

     This program is free software; you can redistribute it and/or modify
     it under only the terms of the GNU General Public License as published by
     the Free Software Foundation; version 2 of the License.

     There are special exceptions to the terms and conditions of the GPL
     as it is applied to this software. View the full text of the
     exception in file EXCEPTIONS-CONNECTOR-C++ in the directory of this
     software distribution.

     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
     */

     /* Standard C++ includes */
     #include <stdlib.h>
     #include <iostream>

     /*
       Include directly the different
       headers from cppconn/ and mysql_driver.h + mysql_util.h
       (and mysql_connection.h). This will reduce your build time!
     */
     #include "mysql_connection.h"

     #include <cppconn/driver.h>
     #include <cppconn/exception.h>
     #include <cppconn/resultset.h>
     #include <cppconn/statement.h>

     using namespace std;

     int main(void)
     {
     cout << endl;
     cout << "Running 'SELECT 'Hello World!' »
        AS _message'..." << endl;

     try {
       sql::Driver *driver;
       sql::Connection *con;
       sql::Statement *stmt;
       sql::ResultSet *res;

       /* Create a connection */
       driver = get_driver_instance();
       con = driver->connect("tcp://127.0.0.1:3306", "root", "root");
       /* Connect to the MySQL test database */
       con->setSchema("test");

       stmt = con->createStatement();
       res = stmt->executeQuery("SELECT 'Hello World!' AS _message");
       while (res->next()) {
         cout << "\t... MySQL replies: ";
         /* Access column data by alias or column name */
         cout << res->getString("_message") << endl;
         cout << "\t... MySQL says it again: ";
         /* Access column fata by numeric offset, 1 is the first column */
         cout << res->getString(1) << endl;
       }
       delete res;
       delete stmt;
       delete con;

     } catch (sql::SQLException &e) {
       cout << "# ERR: SQLException in " << __FILE__;
       cout << "(" << __FUNCTION__ << ") on line " »
          << __LINE__ << endl;
       cout << "# ERR: " << e.what();
       cout << " (MySQL error code: " << e.getErrorCode();
       cout << ", SQLState: " << e.getSQLState() << " )" << endl;
     }

     cout << endl;

     return EXIT_SUCCESS;
     }


File: manual.info,  Node: connector-cpp-examples-complete-example-2,  Prev: connector-cpp-examples-complete-example-1,  Up: connector-cpp-getting-started-examples

20.6.5.6 MySQL Connector/C++ Complete Example 2
...............................................

The following code shows a complete example of how to use MySQL
Connector/C++:

     /* Copyright 2008 Sun Microsystems, Inc.

     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; version 2 of the License.

     There are special exceptions to the terms and conditions of the GPL
     as it is applied to this software. View the full text of the
     exception in file EXCEPTIONS-CONNECTOR-C++ in the directory of this
     software distribution.

     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
     */

     /* Standard C++ includes */
     #include <stdlib.h>
     #include <iostream>

     /*
       Include directly the different
       headers from cppconn/ and mysql_driver.h + mysql_util.h
       (and mysql_connection.h). This will reduce your build time!
     */
     #include "mysql_connection.h"

     #include <cppconn/driver.h>
     #include <cppconn/exception.h>
     #include <cppconn/resultset.h>
     #include <cppconn/statement.h>
     #include <cppconn/prepared_statement.h>

     using namespace std;

     int main(void)
     {
     cout << endl;
     cout << "Let's have MySQL count from 10 to 1..." << endl;

     try {
       sql::Driver *driver;
       sql::Connection *con;
       sql::Statement *stmt;
       sql::ResultSet *res;
       sql::PreparedStatement *pstmt;

       /* Create a connection */
       driver = get_driver_instance();
       con = driver->connect("tcp://127.0.0.1:3306", "root", "root");
       /* Connect to the MySQL test database */
       con->setSchema("test");

       stmt = con->createStatement();
       stmt->execute("DROP TABLE IF EXISTS test");
       stmt->execute("CREATE TABLE test(id INT)");
       delete stmt;

       /* '?' is the supported placeholder syntax */
       pstmt = con->prepareStatement("INSERT INTO test(id) VALUES (?)");
       for (int i = 1; i <= 10; i++) {
         pstmt->setInt(1, i);
         pstmt->executeUpdate();
       }
       delete pstmt;

       /* Select in ascending order */
       pstmt = con->prepareStatement("SELECT id FROM test ORDER BY id ASC");
       res = pstmt->executeQuery();

       /* Fetch in reverse = descending order! */
       res->afterLast();
       while (res->previous())
         cout << "\t... MySQL counts: " << res->getInt("id") << endl;
       delete res;

       delete pstmt;
       delete con;

     } catch (sql::SQLException &e) {
       cout << "# ERR: SQLException in " << __FILE__;
       cout << "(" << __FUNCTION__ << ") on line " »
          << __LINE__ << endl;
       cout << "# ERR: " << e.what();
       cout << " (MySQL error code: " << e.getErrorCode();
       cout << ", SQLState: " << e.getSQLState() << »
          " )" << endl;
     }

     cout << endl;

     return EXIT_SUCCESS;
     }


File: manual.info,  Node: connector-cpp-debug-tracing,  Next: connector-cpp-references,  Prev: connector-cpp-getting-started-examples,  Up: connector-cpp

20.6.6 MySQL Connector/C++ Debug Tracing
----------------------------------------

*Caution*:

Please note, official support is not available for the beta version of
MySQL Connector/C++.

Although a debugger can be used to debug your application, you may find
it beneficial to turn on the debug traces of the connector.  Some
problems happen randomly which makes them difficult to debug using a
debugger. In such cases debug traces and protocol files are more useful
because they allow you to trace the activities of all instances of your
program.

DTrace is a very powerful technology to trace any application without
having to develop an extra trace module for your application.
Unfortunately, DTrace is currently only available on OpenSolaris,
Solaris, MacOS 10.5 and FreeBSD.

The MySQL Connector/C++ can write two trace files:

  1. Trace file generated by the MySQL Client Library

  2. Trace file generated internally by MySQL Connector/C++

The first trace file can be generated by the underlying MySQL Client
Library (libmysql). To enable this trace the connector will call the
C-API function `mysql_debug()' internally. Only debug versions of the
MySQL Client Library are capable of writing a trace file. Therefore you
need to compile MySQL Connector/C++ against a debug version of the
library, if you want utilize this trace. The trace shows the internal
function calls and the addresses of internal objects as you can see
below:

     >mysql_stmt_init
     | >_mymalloc
     | | enter: Size: 816
     | | exit: ptr: 0x68e7b8
     | <_mymalloc | >init_alloc_root
     | | enter: root: 0x68e7b8
     | | >_mymalloc
     | | | enter: Size: 2064
     | | | exit: ptr: 0x68eb28
     [...]

The second trace is the MySQL Connector/C++ internal trace. It is
available with debug and non-debug builds of the connector as long as
you have enabled the tracing module at compile time using `cmake
-DMYSQLCPPCONN_TRACE_ENABLE:BOOL=1'. By default, the tracing
functionality is not available and calls to trace functions are removed
by the preprocessor.

Compiling the connector with tracing functionality enabled will cause
two additional tracing function calls per each connector function call.
You will need to run your own benchmark to find out how much this will
impact the performance of your application.

A simple test using a loop running 30,000 INSERT SQL statements showed
no significant real-time impact. The two variants of this application
using a trace enabled and trace disabled version of the connector
performed equally well. The run time measured in real-time was not
significantly impacted as long as writing a debug trace was not
enabled. However, there will be a difference in the time spent in the
application. When writing a debug trace the IO subsystem may become a
bottleneck.

In summary, use connector builds with tracing enabled carefully.  Trace
enabled versions may cause higher CPU usage even if the overall run
time of your application is not impacted significantly.

     |  INF: Tracing enabled
     <MySQL_Connection::setClientOption
     >MySQL_Prepared_Statement::setInt
     |  INF: this=0x69a2e0
     |  >MySQL_Prepared_Statement::checkClosed
     |  <MySQL_Prepared_Statement::checkClosed
     | <MySQL_Prepared_Statement::setInt
     [...]

The example from `examples/debug.cpp' demonstrates how to activate the
debug traces in your program.  Currently they can only be activated
through API calls. The traces are controlled on a per-connection basis.
You can use the `setClientOptions()' method of a connection object to
activate and deactivate the generation of a trace. The MySQL Client
Library trace is always written into a file, whereas the connector's
protocol messages are printed to standard out.

     sql::Driver *driver;
     int on_off = 1;

     /* Using the Driver to create a connection */
     driver = get_driver_instance();
     std::auto_ptr< sql::Connection > con(driver->connect(host, user, pass));

     /*
     Activate debug trace of the MySQL Client Library (C-API)
     Only available with a debug build of the MySQL Client Library!
     */
     con->setClientOption("libmysql_debug", "d:t:O,client.trace");

     /*
     Tracing is available if you have compiled the driver using
     cmake -DMYSQLCPPCONN_TRACE_ENABLE:BOOL=1
     */
     con->setClientOption("client_trace", &on_off);


File: manual.info,  Node: connector-cpp-references,  Next: connector-cpp-bugs,  Prev: connector-cpp-debug-tracing,  Up: connector-cpp

20.6.7 MySQL Connector/C++ References
-------------------------------------

*Caution*:

Please note, official support is not available for the beta version of
MySQL Connector/C++.

See the JDBC overview (http://java.sun.com/products/jdbc/overview.html)
for information on JDBC 4.0. Please also check the `examples/'
directory of the download package.

*Notes on using the MySQL Connector/C++ API*

   * `DatabaseMetaData::supportsBatchUpdates()' returns `true' because
     MySQL supports batch updates in general. However, no API calls for
     batch updates are provided by the MySQL Connector/C++ API.

   * Two non-JDBC methods have been introduced for fetching and setting
     unsigned integers: `getUInt64()' and `getUInt()'. These are
     available for ResultSet and Prepared_Statement:

        * `ResultSet::getUInt64()'

        * `ResultSet::getUInt()'

        * `Prepared_Statement::setUInt64()'

        * `Prepared_Statement::setUInt()'

     The corresponding `getLong()' and `setLong()' methods have been
     removed.

   * The method `DatabaseMetaData::getColumns()' has 23 columns in its
     result set, rather than the 22 columns defined by JDBC. The first
     22 columns are as described in the JDBC documentation, but column
     23 is new:

     23. `IS_AUTOINCREMENT': String which is `YES' if the column is an
     auto-increment column.  Otherwise the string contains `NO'.

   * MySQL Connector/C++ may return different metadata for the same
     column.

     When you have any column that accepts a charset and a collation in
     its specification and you specify a binary collation, such as:

           CHAR(250) CHARACTER SET 'latin1' COLLATE 'latin1_bin'

     The server sets the `BINARY' flag in the result set metadata of
     this column. The method `ResultSetMetadata::getColumnTypeName()'
     uses the metadata and will report, due to the `BINARY' flag, that
     the column type name is `BINARY'. This is illustrated below:

          mysql> create table varbin(a varchar(20) character set utf8 collate utf8_bin);
          Query OK, 0 rows affected (0.00 sec)

          mysql> select * from varbin;
          Field   1:  `a`
          Catalog:    `def`
          Database:   `test`
          Table:      `varbin`
          Org_table:  `varbin`
          Type:       VAR_STRING
          Collation:  latin1_swedish_ci (8)
          Length:     20
          Max_length: 0
          Decimals:   0
          Flags:      BINARY

          0 rows in set (0.00 sec)

          mysql> select * from information_schema.columns where table_name='varbin'\G
          *************************** 1. row ***************************
                     TABLE_CATALOG: NULL
                      TABLE_SCHEMA: test
                        TABLE_NAME: varbin
                       COLUMN_NAME: a
                  ORDINAL_POSITION: 1
                    COLUMN_DEFAULT: NULL
                       IS_NULLABLE: YES
                         DATA_TYPE: varchar
          CHARACTER_MAXIMUM_LENGTH: 20
            CHARACTER_OCTET_LENGTH: 60
                 NUMERIC_PRECISION: NULL
                     NUMERIC_SCALE: NULL
                CHARACTER_SET_NAME: utf8
                    COLLATION_NAME: utf8_bin
                       COLUMN_TYPE: varchar(20)
                        COLUMN_KEY:
                             EXTRA:
                        PRIVILEGES: select,insert,update,references
                    COLUMN_COMMENT:
          1 row in set (0.01 sec)

     However, `INFORMATION_SCHEMA' gives no hint in its `COLUMNS' table
     that metadata will contain the `BINARY' flag.
     `DatabaseMetaData::getColumns()' uses `INFORMATION_SCHEMA'. It
     will report the type name `CHAR' for the same column. Note, a
     different type code is also returned.

   * The MySQL Connector/C++ class sql::DataType defines the following
     JDBC standard data types: `UNKNOWN', `BIT', `TINYINT', `SMALLINT',
     `MEDIUMINT', `INTEGER', `BIGINT', `REAL', `DOUBLE', `DECIMAL',
     `NUMERIC', `CHAR', `BINARY', `VARCHAR', `VARBINARY', `LONGVARCHAR',
     `LONGVARBINARY', `TIMESTAMP', `DATE', `TIME', `GEOMETRY', `ENUM',
     `SET', `SQLNULL'.

     However, the following JDBC standard data types are _not_
     supported by MySQL Connector/C++: `ARRAY', `BLOB', `CLOB',
     `DISTINCT', `FLOAT', `OTHER', `REF', `STRUCT'.

   * When inserting or updating `BLOB' or `TEXT' columns, MySQL
     Connector/C++ developers are advised not to use `setString()'.
     Instead it is recommended that the dedicated API function
     `setBlob()' be used instead.

     The use of `setString()' can cause a Packet too large
     (http://dev.mysql.com/doc/refman/5.1/en/packet-too-large.html)
     error message. The error will occur if the length of the string
     passed to the connector using `setString()' exceeds
     `max_allowed_packet' (minus a few bytes reserved in the protocol
     for control purposes). This situation is not handled in MySQL
     Connector/C++, as this could lead to security issues, such as
     extremely large memory allocation requests due to malevolently
     long strings.

     However, if `setBlob()' is used, this problem does not arise. This
     is because `setBlob()' takes a streaming approach based on
     `std::istream'. When sending the data from the stream to MySQL
     Server, MySQL Connector/C++ will split the stream into chunks
     appropriate for MySQL Server and observe the `max_allowed_packet'
     setting currently being used.

     *Caution*:

     When using `setString()' it is not possible to set
     `max_packet_size' to a value large enough for the string, prior to
     passing it to MySQL Connector/C++. The MySQL 6.0 documentation
     (http://dev.mysql.com/doc/refman/6.0/en/server-system-variables.html#sysvar_max_allowed_packet)
     for `max_packet_size' states: `As of MySQL 6.0.9, the session
     value of this variable is read only. Before 6.0.9, setting the
     session value is allowed but has no effect.'

     This difference with the JDBC specification ensures that MySQL
     Connector/C++ is not vulnerable to memory flooding attacks.

   * In general MySQL Connector/C++ works with MySQL 5.0, but it is not
     completely supported. Some methods may not be available when
     connecting to MySQL 5.0. This is because the Information Schema is
     used to obtain the requested information. There are no plans to
     improve the support for 5.0 because the current GA version of
     MySQL Server is 5.1. As a new product, MySQL Connector/C++ is
     primarily targeted at the MySQL Server GA version that was
     available on its release.

     The following methods will throw a `sql::MethodNotImplemented'
     exception when you connect to MySQL earlier than 5.1.0:

        * `DatabaseMetadata::getCrossReference()'

        * `DatabaseMetadata::getExportedKeys()'

   * MySQL Connector/C++ includes a method
     `Connection::getClientOption()' which is not included in the JDBC
     API specification. The prototype is:

          void getClientOption(const std::string & optionName, void * optionValue)

     The method can be used to check the value of connection properties
     set when establishing a database connection. The values are
     returned through the `optionValue' argument passed to the method
     with the type `void *'.

     Currently, `getClientOption()' supports fetching the `optionValue'
     of the following options:

        * `metadataUseInfoSchema'

        * `defaultStatementResultType'

        * `defaultPreparedStatementResultType'

     The connection option `metadataUseInfoSchema' controls whether to
     use the `Information_Schemata' for returning the meta data of
     `SHOW' commands. In the case of `metadataUseInfoSchema' the
     `optionValue' argument should be interpreted as a boolean upon
     return.

     In the case of both `defaultStatementResultType' and
     `defaultPreparedStatementResultType', the `optionValue' argument
     should be interpreted as an integer upon return.

     The connection property can be either set when establishing the
     connection through the connection property map or using `void
     Connection::setClientOption(const std::string & optionName, const
     void * optionValue)' where `optionName' is assigned the value
     `metadataUseInfoSchema'.

     Some examples are given below:

          int defaultStmtResType;
          int defaultPStmtResType;
          conn->getClientOption("defaultStatementResultType", (void *) &defaultStmtResType);
          conn->getClientOption("defaultPreparedStatementResultType", (void *) &defaultPStmtResType);

          bool isInfoSchemaUsed;
          conn->getClientOption("metadataUseInfoSchema", (void *) &isInfoSchemaUsed);

   * MySQL Connector/C++ also supports the following methods not found
     in the JDBC API standard:

          std::string MySQL_Connection::getSessionVariable(const std::string & varname)

          void MySQL_Connection::setSessionVariable(const std::string & varname, const std::string & value)

     Note that both methods are members of the `MySQL_Connection'
     class. The methods get and set MySQL session variables.

     `setSessionVariable()' is equivalent to executing:

          SET SESSION <varname> = <value>

     `getSessionVariable()' is equivalent to executing the following
     and fetching the first return value:

          SHOW SESSION VARIABLES LIKE "<varname>"

     You can use `%' and other placeholders in <varname>, if the
     underlying MySQL server supports this.


File: manual.info,  Node: connector-cpp-bugs,  Next: connector-cpp-requests,  Prev: connector-cpp-references,  Up: connector-cpp

20.6.8 MySQL Connector/C++ Known Bugs and Issues
------------------------------------------------

*Caution*:

Please note, official support is not available for the beta version of
MySQL Connector/C++.

*Note*:

Please report bugs through MySQL Bug System (bugs.mysql.com).

* Known bugs: *

None.

* Known issues: *

   * When linking against a static library for 1.0.3 on Windows you
     need to define `CPPDBC_PUBLIC_FUNC' either in the compiler options
     (preferable) or with `/D "CPPCONN_PUBLIC_FUNC="'. You can also
     explicitly define it in your code by placing `#define
     CPPCONN_PUBLIC_FUNC' before the header inclusions.

   * Generally speaking C++ library binaries are less portable than C
     library binaries. Issues can be caused by name mangling, different
     Standard Template Library (STL) versions and using different
     compilers and linkers for linking against the libraries than were
     used for building the library itself.

     Even a small change in the compiler version can, but does not have
     to, cause problems. If you obtain error messages, that you suspect
     are related to binary incompatibilities, build MySQL Connector/C++
     from source, using the same compiler and linker that you will use
     to build and link your application.

     Due to the variations between Linux distributions, compiler and
     linker versions and STL versions, it is not possible to provide
     binaries for each and every possible configuration.  However, the
     MySQL Connector/C++ binary distributions contain a `README' file
     that describes the environment and settings used to build the
     binary versions of the libraries.

   * To avoid potential crashes the build configuration of MySQL
     Connector/C++ should match the build configuration of the
     application using it. For example, do not use the release build of
     MySQL Connector/C++ with a debug build of the client application.

See also the MySQL Connector/C++ Changelogs which can be found here
*Note ccpp-news::.


File: manual.info,  Node: connector-cpp-requests,  Next: connector-cpp-support,  Prev: connector-cpp-bugs,  Up: connector-cpp

20.6.9 MySQL Connector/C++ Feature requests
-------------------------------------------

*Caution*:

Please note, official support is not available for the beta version of
MySQL Connector/C++.

You can suggest new features in the first instance by joining the
mailing list or forum and talking with the developers directly.  See
*Note connector-cpp-support::

The following feature requests are currently being worked on:

   * C++ references for `Statements', `ResultSets', and exceptions, are
     being considered, instead of pointers to heap memory. This reduces
     the exception handling burden for the programmer.

   * Adopt STL (suggestions are welcome).

   * JDBC compliance: datatype interfaces and support through
     `ResultSet:getType()' and `PreparedStatement:bind()'. Introduce
     `sql::Blob', `sql::Clob', `sql::Date', `sql::Time',
     `sql::Timestamp', `sql::URL'. Support `get|setBlob()',
     `get|setClob()', `get|setDate()', `get|setTime()',
     `get|setTimestamp()', `get|setURL()'

   * Add support for all C-API connection options. Improved support for
     `mysql_options'.

   * Add connect method which supports passing options using HashMaps.

   * Create Windows installer.


File: manual.info,  Node: connector-cpp-support,  Next: connector-cpp-faq,  Prev: connector-cpp-requests,  Up: connector-cpp

20.6.10 MySQL Connector/C++ Support
-----------------------------------

*Caution*:

Please note, official support is not available for the beta version of
MySQL Connector/C++.

For general discussion of the MySQL Connector/C++ please use the C/C++
community forum (http://forums.mysql.com/list.php?167) or join the
MySQL Connector/C++ mailing list (http://lists.mysql.com).

Bugs can be reported at the MySQL bug website (http://bugs.mysql.com).

For Licensing questions, and to purchase MySQL Products and Services,
please Contact MySQL (http://www.mysql.com/buy-mysql/)

The MySQL Connector/C++ Changelogs can be found here *Note ccpp-news::


File: manual.info,  Node: connector-cpp-faq,  Prev: connector-cpp-support,  Up: connector-cpp

20.6.11 MySQL Connector/C++ FAQ
-------------------------------

*Questions*
   * 20.6.11.1: What is MySQL Connector/C++?

   * 20.6.11.2: Which MySQL Server version(s) is MySQL Connector/C++
     compatible with?

   * 20.6.11.3: Does MySQL Connector/C++ implement the client-server
     protocol?

   * 20.6.11.4: Are any MySQL products using MySQL Connector/C++?

*Questions and Answers* *20.6.11.1: ** What is MySQL Connector/C++?  *

MySQL Connector/C++ is a MySQL database connector for C++. It allows you
develop applications in C++ that connect to the MySQL Server.  MySQL
Connector/C++ is compatible with the JDBC 4.0 API.

*20.6.11.2: ** Which MySQL Server version(s) is MySQL Connector/C++
compatible with?  *

MySQL Connector/C++ fully supports MySQL Server version 5.1 and later.

*20.6.11.3: ** Does MySQL Connector/C++ implement the client-server
protocol?  *

No. MySQL Connector/C++ uses the MySQL Client Library for the
client-server communication.

*20.6.11.4: ** Are any MySQL products using MySQL Connector/C++?  *

Yes, MySQL Workbench and MySQL Connector/OpenOffice.org.


File: manual.info,  Node: connector-c,  Next: connector-ooo,  Prev: connector-cpp,  Up: connectors-apis

20.7 MySQL Connector/C
======================

* Menu:

* connector-c-building::         Building MySQL Connector/C from the Source Code
* connector-c-testing::          Testing MySQL Connector/C
* connector-c-faq::              MySQL Connector/C FAQ

*What is MySQL Connector/C?*

MySQL Connector/C is a C client library for client-server
communication. It is a standalone replacement for the MySQL Client
Library shipped with the MySQL Server.

*Why have a replacement for MySQL Client Library?*

There is no need to compile or install the MySQL Server package if you
only need the client library.

MySQL Connector/C does not rely on the MySQL Server release cycle, so
bug fixes and new features are released more often.

MySQL Connector/C API documentation is available online
(http://dev.mysql.com/doc/refman/6.0/en/c-api-functions.html).

Supported platforms include:

   * Windows

   * Windows x64

   * Linux

   * Solaris

   * FreeBSD

   * Mac OS X

   * HP-UX

   * IBM AIX

   * IBM i5/OS


File: manual.info,  Node: connector-c-building,  Next: connector-c-testing,  Prev: connector-c,  Up: connector-c

20.7.1 Building MySQL Connector/C from the Source Code
------------------------------------------------------

*Obtaining the Source Code*

The source can be downloaded as a Zip file or tar-ball from the source
repository on Launchpad (http://launchpad.net/libmysql).

   * *Building on Unix*

     Examples of supported Unix or Unix-like operating systems include:

        * Solaris

        * Linux

        * HP-UX

        * AIX

        * OS X

     *Compiler Tools*

     Ideally, the native compiler tool set for the target platform is
     used for compilation. This would be SunStudio for Solaris and aCC
     for HP-UX for example. However, the GNU tool-chain can be used
     across all platforms.

     You also need CMake 2.6 or newer, which is available online
     (http://www.cmake.org).

     *To Build*

     If using GNU AutoTools change to the MySQL Connector/C source
     directory and follow the procedure below.

       1. To generate the makefile enter:

               shell> cmake -G "Unix Makefiles"

          or for a Debug build enter:

               shell> cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Debug

       2. Then build the project using:

               shell> make

     *To Install*

     By default make install will install the MySQL Connector/C files
     in the `/usr/local' directory. You can change this behavior by
     specifying another directory when generating the `makefile':

          shell> cmake -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX=/mypath

     Now, in the root shell, enter the following to install the MySQL
     Connector/C libraries and tools:

          root-shell> make install

     At this point all of the MySQL Connector/C files will be in place.

   * *Building on Microsoft Windows*

     Older versions of Microsoft Windows are not supported.  Supported
     versions are Windows 2000, Windows XP, Windows Vista, Windows
     Server 2003, or Windows Server 2008.

     *Compiler Tools*

     Microsoft Visual Studio 8 and 9 are recommended. The Express
     Edition of Visual Studio and other compilers may work, but are
     untested.

     You also need CMake 2.6 or newer, available at http://www.cmake.org

     *To Build*

     You need to have the environment variables set for the Visual
     Studio toolchain. Visual Studio includes a batch file to set these
     for you, and installs a shortcut into the `Start' menu to open a
     command prompt with these variables set.

     Build MySQL Connector/C using the CMake command-line tool by
     entering the following from the source root directory in a command
     prompt window:

          shell> cmake -G "Visual Studio 9 2008"

     This produces a project file that you can open with Visual Studio
     or build from the command line with either of:

          shell> devenv.com libmysql.sln /build Release

          shell> devenv.com libmysql.sln /build RelWithDebInfo

     For other versions of Visual Studio or `nmake' based build, run
     the following command:

          shell> cmake --help

     to check the supported generators.

     To compile the Debug build, you must run set the CMake build type
     so the correct version of external libraries are used:

          shell> cmake -G "Visual Studio 8 2005" -DCMAKE_BUILD_TYPE=Debug

     Followed by:

          shell> devenv.com libmysql.sln /build Debug

     *To Install*

     To create a install package you can choose between two variants:

       1. Creating a Zip package

       2. Creating an MSI install package

        * *Zip package*

          To create a Zip package, run the `cpack' command from the
          root of your MySQL Connector/C source directory.

        * *MSI Install package*

          The required tools include Windows XML Installer toolset
          (WIX), which is available online
          (http://sourceforge.net/projects/wix/).

          To create the MSI install package change to the subdirectory
          `win' and generate the `makefile':

               shell> cmake -G "NMake Makefiles"

          Create the MSI install package by calling `nmake':

               shell> nmake


File: manual.info,  Node: connector-c-testing,  Next: connector-c-faq,  Prev: connector-c-building,  Up: connector-c

20.7.2 Testing MySQL Connector/C
--------------------------------

For testing MySQL Connector/C you will need a running MySQL server
instance.  Before you run the test suite you need to specify the
following environment variables:

   * `MYSQL_TEST_HOST' (default localhost)

   * `MYSQL_TEST_USER'

   * `MYSQL_TEST_PASSWD'

   * `MYSQL_TEST_PORT'

   * `MYSQL_TEST_SOCKET'

   * `MYSQL_TEST_DB' (default test)

To run the test suite, execute `ctest' from the command line:

     shell> ctest


File: manual.info,  Node: connector-c-faq,  Prev: connector-c-testing,  Up: connector-c

20.7.3 MySQL Connector/C FAQ
----------------------------

*Questions*
   * 20.7.3.1: What is `libmysqld'?

   * 20.7.3.2: What is `MySQL Connector/C'?

   * 20.7.3.3: What is the `MySQL Native C API'? What are its typical
     benefits and use cases?

   * 20.7.3.4: What is the difference between `Native C API',
     `libmysql', `libmysqld' and `MySQL Connector/C'?

   * 20.7.3.5: Does MySQL Connector/C replace any of `Native C API',
     `libmysql' and `libmysqld'?

   * 20.7.3.6: What is `libmysql'?

*Questions and Answers* *20.7.3.1: ** What is `libmysqld'?  *

`libmysqld' is an embedded database server with the same API as MySQL
Connector/C. It is included with the MySQL Server distribution.

*20.7.3.2: ** What is `MySQL Connector/C'?  *

MySQL Connector/C is a standalone distribution of the `libmysql'
library, which was previously only available as part of the MySQL
Server distribution. The version of `libmysql' included with MySQL
Connector/C and the version bundled with the server are functionally
equivalent, but the cross-platform build system for MySQL Connector/C
uses CMake.

*20.7.3.3: ** What is the `MySQL Native C API'? What are its typical
benefits and use cases?  *

MySQL Connector/C, also known as `libmysql', or MySQL Native C API, is
a standalone, C-based API and library that you can use in C
applications to connect with the MySQL Server. It implements the same
MySQL client API that has been in use for a decade.

It is also used as the foundation for drivers for standard database
APIs such as ODBC, Perl's DBI, and Python's DB API.

*20.7.3.4: ** What is the difference between `Native C API',
`libmysql', `libmysqld' and `MySQL Connector/C'?  *

MySQL Connector/C and `libmysql' are the `native C API for MySQL', and
all three terms can be used interchangeably. `libmysqld' is the embedded
version of the MySQL Server, and is included in the server distribution.

*20.7.3.5: ** Does MySQL Connector/C replace any of `Native C API',
`libmysql' and `libmysqld'?  *

MySQL Connector/C contains `libmysql', and implements a native C API.
It does not include `libmysqld', which can be found with the MySQL
server distribution.

*20.7.3.6: ** What is `libmysql'?  *

`libmysql' is the name of the library that MySQL Connector/C provides.


File: manual.info,  Node: connector-ooo,  Next: libmysqld,  Prev: connector-c,  Up: connectors-apis

20.8 MySQL Connector/OpenOffice.org
===================================

* Menu:

* connector-ooo-installation::   Installation
* connector-ooo-getting-started::  Getting Started: Connecting to MySQL
* connector-ooo-getting-started-examples::  Getting Started: Usage Examples
* connector-ooo-references::     References
* connector-ooo-bugs::           Known Bugs
* connector-ooo-contact::        Contact

MySQL Connector/OpenOffice.org is a native MySQL database connector for
OpenOffice.org. Currently, it is in preview status and supports
OpenOffice.org 2.4 only. It can be used to connect OpenOffice.org
applications to a MySQL server.

Before MySQL Connector/OpenOffice.org became available you would have
to use MySQL Connector/J (JDBC) or MySQL Connector/ODBC to connect to a
MySQL server.

Connector/OpenOffice.org is a community project, although Sun
Microsystems actively contributes code. The source code for
Connector/OpenOffice.org is available under GPL with the FLOSS License
Exception.

In the future a closed-source StarOffice version of
Connector/OpenOffice.org will be made available.

*Advantages*

Using MySQL Connector/OpenOffice.org has the following advantages:

   * Easy installation through the OpenOffice.org Extension Manager.

   * Seamless integration into OpenOffice.org.

   * No need to go through an additional Connector installation routine
     (ODBC/JDBC)

   * No need to configure or register an additional Connector (ODBC)

   * No need to install or configure a driver manager (ODBC)

*Status*

MySQL Connector/OpenOffice.org is available as a development preview
version. We kindly ask users and developers to try it out and provide
us with feedback. We do not encourage you to use it in production
environments, though.

*Note*:

Sun Microsystems does not provide formal support for
Connector/OpenOffice.org.

If you have any queries please contact us through our mailing list at
<users@dba.openoffice.org>


File: manual.info,  Node: connector-ooo-installation,  Next: connector-ooo-getting-started,  Prev: connector-ooo,  Up: connector-ooo

20.8.1 Installation
-------------------

  1. Install or upgrade to OpenOffice.org 2.4.

  2. Download MySQL Connector/OpenOffice.org from The OpenOffice.org
     download site
     (http://downloads.mysql.com/forge/openoffice_preview). Save the
     file, `mysql-native-win32.oxt' or `mysql-native-linux.oxt',
     respectively, to a location of your choice, for example `My
     Documents' or `~/Documents'.

  3. Add the `.oxt' extension through the Extension Manager of
     OpenOffice.org. In OpenOffice.org, select `Tools', `Extension
     Manager...' and specify the `.oxt' file as a new extension. When
     done, MySQL Connector/OpenOffice.org will show up as a new
     extension under `My Extensions'.

     FIGURE GOES HERE: Adding an extension

  4. Restart OpenOffice.org.


File: manual.info,  Node: connector-ooo-getting-started,  Next: connector-ooo-getting-started-examples,  Prev: connector-ooo-installation,  Up: connector-ooo

20.8.2 Getting Started: Connecting to MySQL
-------------------------------------------

MySQL Connector/OpenOffice.org allows you to access the MySQL Server
and its schemata from the OpenOffice.org suite. Currently the connector
is in preview status, and only OpenOffice.org 2.4 is supported.

The following example demonstrates the creation of a new OpenOffice.org
Base database which uses a local MySQL Server for storage and the new
connector for connecting.

  1. Select the database

     Create a new database by selecting `File', `New', `Database'. This
     starts a wizard that allows you to create a new, open an existing,
     or connect to existing database. Select the latter option. From
     the drop-down list, select MySQL native driver.  Click `Next >>'.

     FIGURE GOES HERE: Selecting the database

  2. Fill in the connection settings

     Under `MySQL native driver', fill in the host name, and optionally
     a database name, and port name, for example:

     localhost/test

     This will connect to a MySQL server running on the local host and
     select the test database. Note that is you do not specify a
     database the process below will still work, and all databases will
     be available for selection.

     On Linux, you may have to specify an IP number and a port number
     instead, due to a limitation in Connector/OpenOffice.org. You have
     to do so if your MySQL socket file is not `/tmp/mysql.sock'. Enter
     your data using the format illustrated in the following example:

     127.0.0.1:3006/test

     This will connect to a MySQL server running on the local host, but
     do so via TCP/IP using 3306 as the port number. Click `Next >>'.

     FIGURE GOES HERE: Entering connection settings

  3. Fill in credentials

     If you are using MySQL server's anonymous account without a
     password, you do not have to fill in anything in this step.
     Otherwise, fill in your MySQL user name and check the password
     checkbox. Note, for security reasons, you should not normally use
     the anonymous account without a password.

     FIGURE GOES HERE: Setting up user authentication

     You can now test your connection to the MySQL database server by
     clicking the `Test Connection' button.  Check the checkbox if you
     do not want OpenOffice.org to ask you for your password again in
     the current session. Testing the connection is optional, although
     recommended.

     FIGURE GOES HERE: Entering user credentials

     Click `Next >>'.

  4. Finish the wizard

     Leave the default settings and click `Finish'. You will be
     forwarded to the OpenOffice.org Base main window. Note that you
     can invoke the wizard again at any point by right-clicking in the
     `Tables' section of the `Base' main window and selecting
     `Database', `Connection type'.


File: manual.info,  Node: connector-ooo-getting-started-examples,  Next: connector-ooo-references,  Prev: connector-ooo-getting-started,  Up: connector-ooo

20.8.3 Getting Started: Usage Examples
--------------------------------------

*Listing Tables*

In the `Database' area of the `Base' main window, select `Tables'. If
this is the first time you are accessing the database you will be
prompted for your credentials (user name and password); you can store
these settings for your current Base session.

FIGURE GOES HERE: Listing tables

Depending on your connection settings you will now see all databases
with all their tables, or just the database you have specified in the
connection settings.


File: manual.info,  Node: connector-ooo-references,  Next: connector-ooo-bugs,  Prev: connector-ooo-getting-started-examples,  Up: connector-ooo

20.8.4 References
-----------------

See the OpenOffice.org website (http://www.openoffice.org/) for
documentation of the office suite and its Extension Manager.


File: manual.info,  Node: connector-ooo-bugs,  Next: connector-ooo-contact,  Prev: connector-ooo-references,  Up: connector-ooo

20.8.5 Known Bugs
-----------------

If you discover a bug in Connector/OpenOffice.org please add it to this
list
(http://wiki.services.openoffice.org/wiki/Database/Drivers/MySQL_Native#Known_issues)
and send an email to <users@dba.openoffice.org>. You need to be logged
in with an OpenOffice.org account for both; see the project mailing
list (http://dba.openoffice.org/servlets/ProjectMailingListList) for
details.


File: manual.info,  Node: connector-ooo-contact,  Prev: connector-ooo-bugs,  Up: connector-ooo

20.8.6 Contact
--------------

To discuss the new MySQL Connector/OpenOffice.org, please subscribe to
the mailing list <users@dba.openoffice.org>. It is a low-volume list
with less than 10 mails per day.


File: manual.info,  Node: libmysqld,  Next: c,  Prev: connector-ooo,  Up: connectors-apis

20.9 libmysqld, the Embedded MySQL Server Library
=================================================

* Menu:

* libmysqld-compiling::          Compiling Programs with `libmysqld'
* libmysqld-restrictions::       Restrictions When Using the Embedded MySQL Server
* libmysqld-options::            Options with the Embedded Server
* libmysqld-example::            Embedded Server Examples
* libmysqld-licensing::          Licensing the Embedded Server

The embedded MySQL server library makes it possible to run a
full-featured MySQL server inside a client application. The main
benefits are increased speed and more simple management for embedded
applications.

The embedded server library is based on the client/server version of
MySQL, which is written in C/C++. Consequently, the embedded server
also is written in C/C++. There is no embedded server available in
other languages.

The API is identical for the embedded MySQL version and the
client/server version. To change an old threaded application to use the
embedded library, you normally only have to add calls to the following
functions.

*Function*         *When to Call*
*Note              Should be called before any other MySQL function
`mysql_library_init()':is called, preferably early in the `main()'
mysql-library-init.function.
*Note              Should be called before your program exits.
`mysql_library_end()':
mysql-library-end. 
*Note              Should be called in each thread you create that
`mysql_thread_init()':accesses MySQL.
mysql-thread-init. 
*Note              Should be called before calling `pthread_exit()'
`mysql_thread_end()':
mysql-thread-end.  

Then you must link your code with `libmysqld.a' instead of
`libmysqlclient.a'. To ensure binary compatibility between your
application and the server library, be sure to compile your application
against headers for the same series of MySQL that was used to compile
the server library. For example, if `libmysqld' was compiled against
MySQL 4.1 headers, do not compile your application against MySQL 5.1
headers, or vice versa.

The `mysql_library_XXX()' functions are also included in
`libmysqlclient.a' to allow you to change between the embedded and the
client/server version by just linking your application with the right
library. See *Note mysql-library-init::.

One difference between the embedded server and the standalone server is
that for the embedded server, authentication for connections is
disabled by default. To use authentication for the embedded server,
specify the `--with-embedded-privilege-control' option when you invoke
`configure' to configure your MySQL distribution.


File: manual.info,  Node: libmysqld-compiling,  Next: libmysqld-restrictions,  Prev: libmysqld,  Up: libmysqld

20.9.1 Compiling Programs with `libmysqld'
------------------------------------------

In precompiled binary MySQL distributions that include `libmysqld', the
embedded server library, MySQL builds the library using the appropriate
vendor compiler if there is one.

To get a `libmysqld' library if you build MySQL from source yourself,
you should configure MySQL with the `--with-embedded-server' option.
See *Note configure-options::.

When you link your program with `libmysqld', you must also include the
system-specific `pthread' libraries and some libraries that the MySQL
server uses. You can get the full list of libraries by executing *Note
`mysql_config --libmysqld-libs': mysql-config.

The correct flags for compiling and linking a threaded program must be
used, even if you do not directly call any thread functions in your
code.

To compile a C program to include the necessary files to embed the
MySQL server library into an executable version of a program, the
compiler will need to know where to find various files and need
instructions on how to compile the program. The following example shows
how a program could be compiled from the command line, assuming that
you are using `gcc', use the GNU C compiler:

     gcc mysql_test.c -o mysql_test -lz \
     `/usr/local/mysql/bin/mysql_config --include --libmysqld-libs`

Immediately following the `gcc' command is the name of the C program
source file. After it, the `-o' option is given to indicate that the
file name that follows is the name that the compiler is to give to the
output file, the compiled program. The next line of code tells the
compiler to obtain the location of the include files and libraries and
other settings for the system on which it is compiled. Because of a
problem with *Note `mysql_config': mysql-config, the option `-lz' (for
compression) is added here. The *Note `mysql_config': mysql-config.
command is contained in backticks, not single quotes.

On some non-`gcc' platforms, the embedded library depends on C++
runtime libraries and linking against the embedded library might result
in missing-symbol errors. To solve this, link using a C++ compiler or
explicitly list the required libraries on the link command line.


File: manual.info,  Node: libmysqld-restrictions,  Next: libmysqld-options,  Prev: libmysqld-compiling,  Up: libmysqld

20.9.2 Restrictions When Using the Embedded MySQL Server
--------------------------------------------------------

The embedded server has the following limitations:

   * No user-defined functions (UDFs).

   * No stack trace on core dump.

   * You cannot set this up as a master or a slave (no replication).

   * Very large result sets may be unusable on low memory systems.

   * You cannot connect to an embedded server from an outside process
     with sockets or TCP/IP. However, you can connect to an
     intermediate application, which in turn can connect to an embedded
     server on the behalf of a remote client or outside process.

   * `InnoDB' is not reentrant in the embedded server and cannot be
     used for multiple connections, either successively or
     simultaneously.

   * The Event Scheduler is not available. Because of this, the
     `event_scheduler' system variable is disabled.

Some of these limitations can be changed by editing the `mysql_embed.h'
include file and recompiling MySQL.


File: manual.info,  Node: libmysqld-options,  Next: libmysqld-example,  Prev: libmysqld-restrictions,  Up: libmysqld

20.9.3 Options with the Embedded Server
---------------------------------------

Any options that may be given with the *Note `mysqld': mysqld.  server
daemon, may be used with an embedded server library. Server options may
be given in an array as an argument to the *Note
`mysql_library_init()': mysql-library-init, which initializes the
server. They also may be given in an option file like `my.cnf'. To
specify an option file for a C program, use the `--defaults-file'
option as one of the elements of the second argument of the *Note
`mysql_library_init()': mysql-library-init. function. See *Note
mysql-library-init::, for more information on the *Note
`mysql_library_init()': mysql-library-init. function.

Using option files can make it easier to switch between a client/server
application and one where MySQL is embedded. Put common options under
the `[server]' group. These are read by both MySQL versions.
Client/server-specific options should go under the `[mysqld]' section.
Put options specific to the embedded MySQL server library in the
`[embedded]' section. Options specific to applications go under section
labeled `[ApplicationName_SERVER]'. See *Note option-files::.


File: manual.info,  Node: libmysqld-example,  Next: libmysqld-licensing,  Prev: libmysqld-options,  Up: libmysqld

20.9.4 Embedded Server Examples
-------------------------------

These two example programs should work without any changes on a Linux
or FreeBSD system. For other operating systems, minor changes are
needed, mostly with file paths. These examples are designed to give
enough details for you to understand the problem, without the clutter
that is a necessary part of a real application. The first example is
very straightforward. The second example is a little more advanced with
some error checking. The first is followed by a command-line entry for
compiling the program. The second is followed by a GNUmake file that
may be used for compiling instead.

*Example 1*

`test1_libmysqld.c'

     #include <stdio.h>
     #include <stdlib.h>
     #include <stdarg.h>
     #include "mysql.h"

     MYSQL *mysql;
     MYSQL_RES *results;
     MYSQL_ROW record;

     static char *server_options[] = \
            { "mysql_test", "--defaults-file=my.cnf", NULL };
     int num_elements = (sizeof(server_options) / sizeof(char *)) - 1;

     static char *server_groups[] = { "libmysqld_server",
                                      "libmysqld_client", NULL };

     int main(void)
     {
        mysql_library_init(num_elements, server_options, server_groups);
        mysql = mysql_init(NULL);
        mysql_options(mysql, MYSQL_READ_DEFAULT_GROUP, "libmysqld_client");
        mysql_options(mysql, MYSQL_OPT_USE_EMBEDDED_CONNECTION, NULL);

        mysql_real_connect(mysql, NULL,NULL,NULL, "database1", 0,NULL,0);

        mysql_query(mysql, "SELECT column1, column2 FROM table1");

        results = mysql_store_result(mysql);

        while((record = mysql_fetch_row(results))) {
           printf("%s - %s \n", record[0], record[1]);
        }

        mysql_free_result(results);
        mysql_close(mysql);
        mysql_library_end();

        return 0;
     }

Here is the command line for compiling the above program:

     gcc test1_libmysqld.c -o test1_libmysqld -lz \
      `/usr/local/mysql/bin/mysql_config --include --libmysqld-libs`

*Example 2*

To try out the example, create an `test2_libmysqld' directory at the
same level as the MySQL source directory. Save the `test2_libmysqld.c'
source and the `GNUmakefile' in the directory, and run GNU `make' from
inside the `test2_libmysqld' directory.

`test2_libmysqld.c'

     /*
      * A simple example client, using the embedded MySQL server library
     */

     #include <mysql.h>
     #include <stdarg.h>
     #include <stdio.h>
     #include <stdlib.h>

     MYSQL *db_connect(const char *dbname);
     void db_disconnect(MYSQL *db);
     void db_do_query(MYSQL *db, const char *query);

     const char *server_groups[] = {
       "test2_libmysqld_SERVER", "embedded", "server", NULL
     };

     int
     main(int argc, char **argv)
     {
       MYSQL *one, *two;

       /* mysql_library_init() must be called before any other mysql
        * functions.
        *
        * You can use mysql_library_init(0, NULL, NULL), and it
        * initializes the server using groups = {
        *   "server", "embedded", NULL
        *  }.
        *
        * In your $HOME/.my.cnf file, you probably want to put:

     [test2_libmysqld_SERVER]
     language = /path/to/source/of/mysql/sql/share/english

        * You could, of course, modify argc and argv before passing
        * them to this function.  Or you could create new ones in any
        * way you like.  But all of the arguments in argv (except for
        * argv[0], which is the program name) should be valid options
        * for the MySQL server.
        *
        * If you link this client against the normal mysqlclient
        * library, this function is just a stub that does nothing.
        */
       mysql_library_init(argc, argv, (char **)server_groups);

       one = db_connect("test");
       two = db_connect(NULL);

       db_do_query(one, "SHOW TABLE STATUS");
       db_do_query(two, "SHOW DATABASES");

       mysql_close(two);
       mysql_close(one);

       /* This must be called after all other mysql functions */
       mysql_library_end();

       exit(EXIT_SUCCESS);
     }

     static void
     die(MYSQL *db, char *fmt, ...)
     {
       va_list ap;
       va_start(ap, fmt);
       vfprintf(stderr, fmt, ap);
       va_end(ap);
       (void)putc('\n', stderr);
       if (db)
         db_disconnect(db);
       exit(EXIT_FAILURE);
     }

     MYSQL *
     db_connect(const char *dbname)
     {
       MYSQL *db = mysql_init(NULL);
       if (!db)
         die(db, "mysql_init failed: no memory");
       /*
        * Notice that the client and server use separate group names.
        * This is critical, because the server does not accept the
        * client's options, and vice versa.
        */
       mysql_options(db, MYSQL_READ_DEFAULT_GROUP, "test2_libmysqld_CLIENT");
       if (!mysql_real_connect(db, NULL, NULL, NULL, dbname, 0, NULL, 0))
         die(db, "mysql_real_connect failed: %s", mysql_error(db));

       return db;
     }

     void
     db_disconnect(MYSQL *db)
     {
       mysql_close(db);
     }

     void
     db_do_query(MYSQL *db, const char *query)
     {
       if (mysql_query(db, query) != 0)
         goto err;

       if (mysql_field_count(db) > 0)
       {
         MYSQL_RES   *res;
         MYSQL_ROW    row, end_row;
         int num_fields;

         if (!(res = mysql_store_result(db)))
           goto err;
         num_fields = mysql_num_fields(res);
         while ((row = mysql_fetch_row(res)))
         {
           (void)fputs(">> ", stdout);
           for (end_row = row + num_fields; row < end_row; ++row)
             (void)printf("%s\t", row ? (char*)*row : "NULL");
           (void)fputc('\n', stdout);
         }
         (void)fputc('\n', stdout);
         mysql_free_result(res);
       }
       else
         (void)printf("Affected rows: %lld\n", mysql_affected_rows(db));

       return;

     err:
       die(db, "db_do_query failed: %s [%s]", mysql_error(db), query);
     }

`GNUmakefile'

     # This assumes the MySQL software is installed in /usr/local/mysql
     inc      := /usr/local/mysql/include/mysql
     lib      := /usr/local/mysql/lib

     # If you have not installed the MySQL software yet, try this instead
     #inc      := $(HOME)/mysql-6.0/include
     #lib      := $(HOME)/mysql-6.0/libmysqld

     CC       := gcc
     CPPFLAGS := -I$(inc) -D_THREAD_SAFE -D_REENTRANT
     CFLAGS   := -g -W -Wall
     LDFLAGS  := -static
     # You can change -lmysqld to -lmysqlclient to use the
     # client/server library
     LDLIBS    = -L$(lib) -lmysqld -lz -lm -ldl -lcrypt

     ifneq (,$(shell grep FreeBSD /COPYRIGHT 2>/dev/null))
     # FreeBSD
     LDFLAGS += -pthread
     else
     # Assume Linux
     LDLIBS += -lpthread
     endif

     # This works for simple one-file test programs
     sources := $(wildcard *.c)
     objects := $(patsubst %c,%o,$(sources))
     targets := $(basename $(sources))

     all: $(targets)

     clean:
             rm -f $(targets) $(objects) *.core


File: manual.info,  Node: libmysqld-licensing,  Prev: libmysqld-example,  Up: libmysqld

20.9.5 Licensing the Embedded Server
------------------------------------

We encourage everyone to promote free software by releasing code under
the GPL or a compatible license. For those who are not able to do this,
another option is to purchase a commercial license for the MySQL code
from Sun Microsystems, Inc. For details, please see
`http://www.mysql.com/company/legal/licensing/'.


File: manual.info,  Node: c,  Next: apis-php,  Prev: libmysqld,  Up: connectors-apis

20.10 MySQL C API
=================

* Menu:

* c-api-datatypes::              C API Data Types
* c-api-function-overview::      C API Function Overview
* c-api-functions::              C API Function Descriptions
* c-api-prepared-statements::    C API Prepared Statements
* c-api-prepared-statement-datatypes::  C API Prepared Statement Data types
* c-api-prepared-statement-function-overview::  C API Prepared Statement Function Overview
* c-api-prepared-statement-functions::  C API Prepared Statement Function Descriptions
* c-thread-functions::           C API Threaded Function Descriptions
* c-embedded-server-functions::  C API Embedded Server Function Descriptions
* c-api-problems::               Common Questions and Problems When Using the C API
* auto-reconnect::               Controlling Automatic Reconnection Behavior
* c-api-multiple-queries::       C API Support for Multiple Statement Execution
* c-api-prepared-statement-problems::  C API Prepared Statement Problems
* c-api-prepared-statement-date-handling::  C API Prepared Statement Handling of Date and Time Values
* c-api-prepared-call-statements::  C API Support for Prepared `CALL' Statements
* building-clients::             Building Client Programs
* threaded-clients::             How to Make a Threaded Client

The C API code is distributed with MySQL. It is included in the
`mysqlclient' library and allows C programs to access a database.

Many of the clients in the MySQL source distribution are written in C.
If you are looking for examples that demonstrate how to use the C API,
take a look at these clients. You can find these in the `client'
directory in the MySQL source distribution.

Most of the other client APIs (all except Connector/J and
Connector/NET) use the `mysqlclient' library to communicate with the
MySQL server. This means that, for example, you can take advantage of
many of the same environment variables that are used by other client
programs, because they are referenced from the library. See *Note
programs::, for a list of these variables.

The client has a maximum communication buffer size. The size of the
buffer that is allocated initially (16KB) is automatically increased up
to the maximum size (the maximum is 16MB). Because buffer sizes are
increased only as demand warrants, simply increasing the default
maximum limit does not in itself cause more resources to be used.  This
size check is mostly a check for erroneous statements and communication
packets.

The communication buffer must be large enough to contain a single SQL
statement (for client-to-server traffic) and one row of returned data
(for server-to-client traffic). Each thread's communication buffer is
dynamically enlarged to handle any query or row up to the maximum
limit. For example, if you have *Note `BLOB': blob. values that contain
up to 16MB of data, you must have a communication buffer limit of at
least 16MB (in both server and client). The client's default maximum is
16MB, but the default maximum in the server is 1MB. You can increase
this by changing the value of the `max_allowed_packet' parameter when
the server is started. See *Note server-parameters::.

The MySQL server shrinks each communication buffer to
`net_buffer_length' bytes after each query. For clients, the size of
the buffer associated with a connection is not decreased until the
connection is closed, at which time client memory is reclaimed.

For programming with threads, see *Note threaded-clients::. For
creating a standalone application which includes the "server" and
"client" in the same program (and does not communicate with an external
MySQL server), see *Note libmysqld::.


File: manual.info,  Node: c-api-datatypes,  Next: c-api-function-overview,  Prev: c,  Up: c

20.10.1 C API Data Types
------------------------

This section describes C API data types other than those used for
prepared statements. For information about the latter, see *Note
c-api-prepared-statement-datatypes::.

   * `MYSQL'

     This structure represents a handle to one database connection.  It
     is used for almost all MySQL functions. You should not try to make
     a copy of a `MYSQL' structure. There is no guarantee that such a
     copy will be usable.

   * `MYSQL_RES'

     This structure represents the result of a query that returns rows
     (*Note `SELECT': select, *Note `SHOW': show, *Note `DESCRIBE':
     describe, *Note `EXPLAIN': explain.). The information returned
     from a query is called the _result set_ in the remainder of this
     section.

   * `MYSQL_ROW'

     This is a type-safe representation of one row of data. It is
     currently implemented as an array of counted byte strings.  (You
     cannot treat these as null-terminated strings if field values may
     contain binary data, because such values may contain null bytes
     internally.) Rows are obtained by calling *Note
     `mysql_fetch_row()': mysql-fetch-row.

   * `MYSQL_FIELD'

     This structure contains information about a field, such as the
     field's name, type, and size. Its members are described in more
     detail here. You may obtain the `MYSQL_FIELD' structures for each
     field by calling *Note `mysql_fetch_field()': mysql-fetch-field.
     repeatedly. Field values are not part of this structure; they are
     contained in a `MYSQL_ROW' structure.

   * `MYSQL_FIELD_OFFSET'

     This is a type-safe representation of an offset into a MySQL field
     list. (Used by *Note `mysql_field_seek()': mysql-field-seek.)
     Offsets are field numbers within a row, beginning at zero.

   * `my_ulonglong'

     The type used for the number of rows and for *Note
     `mysql_affected_rows()': mysql-affected-rows, *Note
     `mysql_num_rows()': mysql-num-rows, and *Note `mysql_insert_id()':
     mysql-insert-id. This type provides a range of `0' to `1.84e19'.

     On some systems, attempting to print a value of type
     `my_ulonglong' does not work. To print such a value, convert it to
     `unsigned long' and use a `%lu' print format. Example:

          printf ("Number of rows: %lu\n",
                  (unsigned long) mysql_num_rows(result));

   * `my_bool'

     A boolean type, for values that are true (non-zero) or false
     (zero).

The `MYSQL_FIELD' structure contains the members described in the
following list. The definitions apply primarily for columns of result
sets such as those produced by *Note `SELECT': select. statements. As
of MySQL 6.0.8, `MYSQL_FIELD' structures are also used to provide
metadata for `OUT' and `INOUT' parameters returned from stored
procedures executed via prepared *Note `CALL': call. statements. For
such parameters, some of the structure members have a meaning different
from the meaning for column values.

   * `char * name'

     The name of the field, as a null-terminated string. If the field
     was given an alias with an `AS' clause, the value of `name' is the
     alias. For a procedure parameter, the parameter name.

   * `char * org_name'

     The name of the field, as a null-terminated string. Aliases are
     ignored. For a procedure parameter, the parameter name.

   * `char * table'

     The name of the table containing this field, if it isn't a
     calculated field. For calculated fields, the `table' value is an
     empty string. If the column is selected from a view, `table' names
     the view. If the table or view was given an alias with an `AS'
     clause, the value of `table' is the alias. For a *Note `UNION':
     union, the value is the empty string. For a procedure parameter,
     the procedure name.

   * `char * org_table'

     The name of the table, as a null-terminated string. Aliases are
     ignored. If the column is selected from a view, `org_table' names
     the underlying table. For a *Note `UNION': union, the value is the
     empty string. For a procedure parameter, the procedure name.

   * `char * db'

     The name of the database that the field comes from, as a
     null-terminated string. If the field is a calculated field, `db'
     is an empty string. For a *Note `UNION': union, the value is the
     empty string. For a procedure parameter, the name of the database
     containing the procedure.

   * `char * catalog'

     The catalog name. This value is always `"def"'.

   * `char * def'

     The default value of this field, as a null-terminated string.
     This is set only if you use *Note `mysql_list_fields()':
     mysql-list-fields.

   * `unsigned long length'

     The width of the field. This corresponds to the display length, in
     bytes.

   * `unsigned long max_length'

     The maximum width of the field for the result set (the length in
     bytes of the longest field value for the rows actually in the
     result set). If you use *Note `mysql_store_result()':
     mysql-store-result. or *Note `mysql_list_fields()':
     mysql-list-fields, this contains the maximum length for the field.
     If you use *Note `mysql_use_result()': mysql-use-result, the value
     of this variable is zero.

     The value of `max_length' is the length of the string
     representation of the values in the result set. For example, if
     you retrieve a *Note `FLOAT': numeric-types. column and the
     `widest' value is `-12.345', `max_length' is 7 (the length of
     `'-12.345'').

     If you are using prepared statements, `max_length' is not set by
     default because for the binary protocol the lengths of the values
     depend on the types of the values in the result set. (See *Note
     c-api-prepared-statement-datatypes::.) If you want the
     `max_length' values anyway, enable the
     `STMT_ATTR_UPDATE_MAX_LENGTH' option with *Note
     `mysql_stmt_attr_set()': mysql-stmt-attr-set. and the lengths will
     be set when you call *Note `mysql_stmt_store_result()':
     mysql-stmt-store-result.  (See *Note mysql-stmt-attr-set::, and
     *Note mysql-stmt-store-result::.)

   * `unsigned int name_length'

     The length of `name'.

   * `unsigned int org_name_length'

     The length of `org_name'.

   * `unsigned int table_length'

     The length of `table'.

   * `unsigned int org_table_length'

     The length of `org_table'.

   * `unsigned int db_length'

     The length of `db'.

   * `unsigned int catalog_length'

     The length of `catalog'.

   * `unsigned int def_length'

     The length of `def'.

   * `unsigned int flags'

     Different bit-flags for the field. The `flags' value may have zero
     or more of the following bits set.

     *Flag Value*                *Flag Description*
     `NOT_NULL_FLAG'             Field can't be `NULL'
     `PRI_KEY_FLAG'              Field is part of a primary key
     `UNIQUE_KEY_FLAG'           Field is part of a unique key
     `MULTIPLE_KEY_FLAG'         Field is part of a non-unique key
     `UNSIGNED_FLAG'             Field has the `UNSIGNED' attribute
     `ZEROFILL_FLAG'             Field has the `ZEROFILL' attribute
     `BINARY_FLAG'               Field has the `BINARY' attribute
     `AUTO_INCREMENT_FLAG'       Field has the `AUTO_INCREMENT' attribute
     `ENUM_FLAG'                 Field is an *Note `ENUM': enum.
                                 (deprecated)
     `SET_FLAG'                  Field is a *Note `SET': set.
                                 (deprecated)
     `BLOB_FLAG'                 Field is a *Note `BLOB': blob. or *Note
                                 `TEXT': blob. (deprecated)
     `TIMESTAMP_FLAG'            Field is a *Note `TIMESTAMP': datetime.
                                 (deprecated)
     `NO_DEFAULT_VALUE_FLAG'     Field has no default value; see
                                 additional notes following table

     Use of the `BLOB_FLAG', `ENUM_FLAG', `SET_FLAG', and
     `TIMESTAMP_FLAG' flags is deprecated because they indicate the
     type of a field rather than an attribute of its type. It is
     preferable to test `field->type' against `MYSQL_TYPE_BLOB',
     `MYSQL_TYPE_ENUM', `MYSQL_TYPE_SET', or `MYSQL_TYPE_TIMESTAMP'
     instead.

     `NUM_FLAG' indicates that a column is numeric. This includes
     columns with a type of `MYSQL_TYPE_DECIMAL', `MYSQL_TYPE_TINY',
     `MYSQL_TYPE_SHORT', `MYSQL_TYPE_LONG', `MYSQL_TYPE_FLOAT',
     `MYSQL_TYPE_DOUBLE', `MYSQL_TYPE_NULL', `MYSQL_TYPE_TIMESTAMP',
     `MYSQL_TYPE_LONGLONG', `MYSQL_TYPE_INT24', and `MYSQL_TYPE_YEAR'.

     `NO_DEFAULT_VALUE_FLAG' indicates that a column has no `DEFAULT'
     clause in its definition. This does not apply to `NULL' columns
     (because such columns have a default of `NULL'), or to
     `AUTO_INCREMENT' columns (which have an implied default value).

     The following example illustrates a typical use of the `flags'
     value:

          if (field->flags & NOT_NULL_FLAG)
              printf("Field can't be null\n");

     You may use the following convenience macros to determine the
     boolean status of the `flags' value.

     *Flag Status*               *Description*
     `IS_NOT_NULL(flags)'        True if this field is defined as `NOT
                                 NULL'
     `IS_PRI_KEY(flags)'         True if this field is a primary key
     `IS_BLOB(flags)'            True if this field is a *Note `BLOB':
                                 blob. or *Note `TEXT': blob.
                                 (deprecated; test `field->type' instead)

   * `unsigned int decimals'

     The number of decimals for numeric fields.

   * `unsigned int charsetnr'

     An ID number that indicates the character set/collation pair for
     the field.

     To distinguish between binary and non-binary data for string data
     types, check whether the `charsetnr' value is 63. If so, the
     character set is `binary', which indicates binary rather than
     non-binary data. This enables you to distinguish *Note `BINARY':
     binary-varbinary. from *Note `CHAR': char, *Note `VARBINARY':
     binary-varbinary. from *Note `VARCHAR': char, and the *Note
     `BLOB': blob. types from the *Note `TEXT': blob. types.

     `charsetnr' values are the same as those displayed in the `Id'
     column of the *Note `SHOW COLLATION': show-collation. statement or
     the `ID' column of the `INFORMATION_SCHEMA' *Note `COLLATIONS':
     collations-table. table. You can use those information sources to
     see which character set and collation specific `charsetnr' values
     indicate:

          mysql> SHOW COLLATION WHERE Id = 63;
          +-----------+---------+----+---------+----------+---------+
          | Collation | Charset | Id | Default | Compiled | Sortlen |
          +-----------+---------+----+---------+----------+---------+
          | binary    | binary  | 63 | Yes     | Yes      |       1 |
          +-----------+---------+----+---------+----------+---------+

          mysql> SELECT COLLATION_NAME, CHARACTER_SET_NAME
              -> FROM INFORMATION_SCHEMA.COLLATIONS WHERE ID = 33;
          +-----------------+--------------------+
          | COLLATION_NAME  | CHARACTER_SET_NAME |
          +-----------------+--------------------+
          | utf8_general_ci | utf8               |
          +-----------------+--------------------+

   * `enum enum_field_types type'

     The type of the field. The `type' value may be one of the
     `MYSQL_TYPE_' symbols shown in the following table.

     *Type Value*            *Type Description*
     `MYSQL_TYPE_TINY'       *Note `TINYINT': numeric-types. field
     `MYSQL_TYPE_SHORT'      *Note `SMALLINT': numeric-types. field
     `MYSQL_TYPE_LONG'       *Note `INTEGER': numeric-types. field
     `MYSQL_TYPE_INT24'      *Note `MEDIUMINT': numeric-types. field
     `MYSQL_TYPE_LONGLONG'   *Note `BIGINT': numeric-types. field
     `MYSQL_TYPE_DECIMAL'    *Note `DECIMAL': numeric-types. or *Note
                             `NUMERIC': numeric-types. field
     `MYSQL_TYPE_NEWDECIMAL' Precision math *Note `DECIMAL':
                             numeric-types. or *Note `NUMERIC':
                             numeric-types.
     `MYSQL_TYPE_FLOAT'      *Note `FLOAT': numeric-types. field
     `MYSQL_TYPE_DOUBLE'     *Note `DOUBLE': numeric-types. or *Note
                             `REAL': numeric-types. field
     `MYSQL_TYPE_BIT'        *Note `BIT': numeric-types. field
     `MYSQL_TYPE_TIMESTAMP'  *Note `TIMESTAMP': datetime. field
     `MYSQL_TYPE_DATE'       *Note `DATE': datetime. field
     `MYSQL_TYPE_TIME'       *Note `TIME': time. field
     `MYSQL_TYPE_DATETIME'   *Note `DATETIME': datetime. field
     `MYSQL_TYPE_YEAR'       *Note `YEAR': year. field
     `MYSQL_TYPE_STRING'     *Note `CHAR': char. or *Note `BINARY':
                             binary-varbinary. field
     `MYSQL_TYPE_VAR_STRING' *Note `VARCHAR': char. or *Note
                             `VARBINARY': binary-varbinary. field
     `MYSQL_TYPE_BLOB'       *Note `BLOB': blob. or *Note `TEXT': blob.
                             field (use `max_length' to determine the
                             maximum length)
     `MYSQL_TYPE_SET'        *Note `SET': set. field
     `MYSQL_TYPE_ENUM'       *Note `ENUM': enum. field
     `MYSQL_TYPE_GEOMETRY'   Spatial field
     `MYSQL_TYPE_NULL'       `NULL'-type field

     You can use the `IS_NUM()' macro to test whether a field has a
     numeric type. Pass the `type' value to `IS_NUM()' and it evaluates
     to TRUE if the field is numeric:

          if (IS_NUM(field->type))
              printf("Field is numeric\n");


File: manual.info,  Node: c-api-function-overview,  Next: c-api-functions,  Prev: c-api-datatypes,  Up: c

20.10.2 C API Function Overview
-------------------------------

The functions available in the C API are summarized here and described
in greater detail in a later section. See *Note c-api-functions::.

*Function*              *Description*
*Note `my_init()':      Initialize global variables, and thread handler
my-init.                in thread-safe programs
*Note                   Returns the number of rows
`mysql_affected_rows()':changed/deleted/inserted by the last *Note
mysql-affected-rows.    `UPDATE': update, *Note `DELETE': delete, or
                        *Note `INSERT': insert. query
*Note                   Toggles autocommit mode on/off
`mysql_autocommit()':   
mysql-autocommit.       
*Note                   Changes user and database on an open connection
`mysql_change_user()':  
mysql-change-user.      
*Note                   Return default character set name for current
`mysql_character_set_name()':connection
mysql-character-set-name.
*Note `mysql_close()':  Closes a server connection
mysql-close.            
*Note                   Commits the transaction
`mysql_commit()':       
mysql-commit.           
*Note                   Connects to a MySQL server (this function is
`mysql_connect()':      deprecated; use *Note `mysql_real_connect()':
mysql-connect.          mysql-real-connect.  instead)
*Note                   Creates a database (this function is deprecated;
`mysql_create_db()':    use the SQL statement *Note `CREATE DATABASE':
mysql-create-db.        create-database. instead)
*Note                   Seeks to an arbitrary row number in a query
`mysql_data_seek()':    result set
mysql-data-seek.        
*Note `mysql_debug()':  Does a `DBUG_PUSH' with the given string
mysql-debug.            
*Note                   Drops a database (this function is deprecated;
`mysql_drop_db()':      use the SQL statement *Note `DROP DATABASE':
mysql-drop-db.          drop-database. instead)
*Note                   Makes the server write debug information to the
`mysql_dump_debug_info()':log
mysql-dump-debug-info.  
*Note `mysql_eof()':    Determines whether the last row of a result set
mysql-eof.              has been read (this function is deprecated;
                        *Note `mysql_errno()': mysql-errno. or *Note
                        `mysql_error()': mysql-error. may be used
                        instead)
*Note `mysql_errno()':  Returns the error number for the most recently
mysql-errno.            invoked MySQL function
*Note `mysql_error()':  Returns the error message for the most recently
mysql-error.            invoked MySQL function
*Note                   Escapes special characters in a string for use
`mysql_escape_string()':in an SQL statement
mysql-escape-string.    
*Note                   Returns the type of the next table field
`mysql_fetch_field()':  
mysql-fetch-field.      
*Note                   Returns the type of a table field, given a field
`mysql_fetch_field_direct()':number
mysql-fetch-field-direct.
*Note                   Returns an array of all field structures
`mysql_fetch_fields()': 
mysql-fetch-fields.     
*Note                   Returns the lengths of all columns in the
`mysql_fetch_lengths()':current row
mysql-fetch-lengths.    
*Note                   Fetches the next row from the result set
`mysql_fetch_row()':    
mysql-fetch-row.        
*Note                   Returns the number of result columns for the
`mysql_field_count()':  most recent statement
mysql-field-count.      
*Note                   Puts the column cursor on a specified column
`mysql_field_seek()':   
mysql-field-seek.       
*Note                   Returns the position of the field cursor used
`mysql_field_tell()':   for the last *Note `mysql_fetch_field()':
mysql-field-tell.       mysql-fetch-field.
*Note                   Frees memory used by a result set
`mysql_free_result()':  
mysql-free-result.      
*Note                   Return information about default character set
`mysql_get_character_set_info()':
mysql-get-character-set-info.
*Note                   Returns client version information as a string
`mysql_get_client_info()':
mysql-get-client-info.  
*Note                   Returns client version information as an integer
`mysql_get_client_version()':
mysql-get-client-version.
*Note                   Returns a string describing the connection
`mysql_get_host_info()':
mysql-get-host-info.    
*Note                   Returns the protocol version used by the
`mysql_get_proto_info()':connection
mysql-get-proto-info.   
*Note                   Returns the server version number
`mysql_get_server_info()':
mysql-get-server-info.  
*Note                   Returns version number of server as an integer
`mysql_get_server_version()':
mysql-get-server-version.
*Note                   Return current SSL cipher
`mysql_get_ssl_cipher()':
mysql-get-ssl-cipher.   
*Note                   Encode string in hexadecimal format
`mysql_hex_string()':   
mysql-hex-string.       
*Note `mysql_info()':   Returns information about the most recently
mysql-info.             executed query
*Note `mysql_init()':   Gets or initializes a `MYSQL' structure
mysql-init.             
*Note                   Returns the ID generated for an `AUTO_INCREMENT'
`mysql_insert_id()':    column by the previous query
mysql-insert-id.        
*Note `mysql_kill()':   Kills a given thread
mysql-kill.             
*Note                   Finalize the MySQL C API library
`mysql_library_end()':  
mysql-library-end.      
*Note                   Initialize the MySQL C API library
`mysql_library_init()': 
mysql-library-init.     
*Note                   Returns database names matching a simple regular
`mysql_list_dbs()':     expression
mysql-list-dbs.         
*Note                   Returns field names matching a simple regular
`mysql_list_fields()':  expression
mysql-list-fields.      
*Note                   Returns a list of the current server threads
`mysql_list_processes()':
mysql-list-processes.   
*Note                   Returns table names matching a simple regular
`mysql_list_tables()':  expression
mysql-list-tables.      
*Note                   Checks whether any more results exist
`mysql_more_results()': 
mysql-more-results.     
*Note                   Returns/initiates the next result in
`mysql_next_result()':  multiple-result executions
mysql-next-result.      
*Note                   Returns the number of columns in a result set
`mysql_num_fields()':   
mysql-num-fields.       
*Note                   Returns the number of rows in a result set
`mysql_num_rows()':     
mysql-num-rows.         
*Note                   Sets connect options for *Note
`mysql_options()':      `mysql_real_connect()': mysql-real-connect.
mysql-options.          
*Note `mysql_ping()':   Checks whether the connection to the server is
mysql-ping.             working, reconnecting as necessary
*Note `mysql_query()':  Executes an SQL query specified as a
mysql-query.            null-terminated string
*Note                   Connects to a MySQL server
`mysql_real_connect()': 
mysql-real-connect.     
*Note                   Escapes special characters in a string for use
`mysql_real_escape_string()':in an SQL statement, taking into account the
mysql-real-escape-string.current character set of the connection
*Note                   Executes an SQL query specified as a counted
`mysql_real_query()':   string
mysql-real-query.       
*Note                   Flush or reset tables and caches
`mysql_refresh()':      
mysql-refresh.          
*Note                   Tells the server to reload the grant tables
`mysql_reload()':       
mysql-reload.           
*Note                   Rolls back the transaction
`mysql_rollback()':     
mysql-rollback.         
*Note                   Seeks to a row offset in a result set, using
`mysql_row_seek()':     value returned from *Note `mysql_row_tell()':
mysql-row-seek.         mysql-row-tell.
*Note                   Returns the row cursor position
`mysql_row_tell()':     
mysql-row-tell.         
*Note                   Selects a database
`mysql_select_db()':    
mysql-select-db.        
*Note                   Finalize the MySQL C API library
`mysql_server_end()':   
mysql-server-end.       
*Note                   Initialize the MySQL C API library
`mysql_server_init()':  
mysql-server-init.      
*Note                   Set default character set for current connection
`mysql_set_character_set()':
mysql-set-character-set.
*Note                   Set the *Note `LOAD DATA LOCAL INFILE':
`mysql_set_local_infile_default()':load-data. handler callbacks to their default
mysql-set-local-infile-default.values
*Note                   Install application-specific *Note `LOAD DATA
`mysql_set_local_infile_handler()':LOCAL INFILE': load-data. handler callbacks
mysql-set-local-infile-handler.
*Note                   Sets an option for the connection (like
`mysql_set_server_option()':`multi-statements')
mysql-set-server-option.
*Note                   Returns the SQLSTATE error code for the last
`mysql_sqlstate()':     error
mysql-sqlstate.         
*Note                   Shuts down the database server
`mysql_shutdown()':     
mysql-shutdown.         
*Note                   Prepare to establish SSL connection to server
`mysql_ssl_set()':      
mysql-ssl-set.          
*Note `mysql_stat()':   Returns the server status as a string
mysql-stat.             
*Note                   Retrieves a complete result set to the client
`mysql_store_result()': 
mysql-store-result.     
*Note                   Finalize thread handler
`mysql_thread_end()':   
mysql-thread-end.       
*Note                   Returns the current thread ID
`mysql_thread_id()':    
mysql-thread-id.        
*Note                   Initialize thread handler
`mysql_thread_init()':  
mysql-thread-init.      
*Note                   Returns 1 if the clients are compiled as
`mysql_thread_safe()':  thread-safe
mysql-thread-safe.      
*Note                   Initiates a row-by-row result set retrieval
`mysql_use_result()':   
mysql-use-result.       
*Note                   Returns the warning count for the previous SQL
`mysql_warning_count()':statement
mysql-warning-count.    

Application programs should use this general outline for interacting
with MySQL:

  1. Initialize the MySQL library by calling *Note
     `mysql_library_init()': mysql-library-init. This function exists
     in both the `mysqlclient' C client library and the `mysqld'
     embedded server library, so it is used whether you build a regular
     client program by linking with the `-libmysqlclient' flag, or an
     embedded server application by linking with the `-libmysqld' flag.

  2. Initialize a connection handler by calling *Note `mysql_init()':
     mysql-init. and connect to the server by calling *Note
     `mysql_real_connect()': mysql-real-connect.

  3. Issue SQL statements and process their results. (The following
     discussion provides more information about how to do this.)

  4. Close the connection to the MySQL server by calling *Note
     `mysql_close()': mysql-close.

  5. End use of the MySQL library by calling *Note
     `mysql_library_end()': mysql-library-end.

The purpose of calling *Note `mysql_library_init()':
mysql-library-init. and *Note `mysql_library_end()': mysql-library-end.
is to provide proper initialization and finalization of the MySQL
library. For applications that are linked with the client library, they
provide improved memory management. If you don't call *Note
`mysql_library_end()': mysql-library-end, a block of memory remains
allocated. (This does not increase the amount of memory used by the
application, but some memory leak detectors will complain about it.)
For applications that are linked with the embedded server, these calls
start and stop the server.

In a non-multi-threaded environment, the call to *Note
`mysql_library_init()': mysql-library-init. may be omitted, because
*Note `mysql_init()': mysql-init. will invoke it automatically as
necessary. However, *Note `mysql_library_init()': mysql-library-init.
is not thread-safe in a multi-threaded environment, and thus neither is
*Note `mysql_init()': mysql-init, which calls *Note
`mysql_library_init()': mysql-library-init. You must either call *Note
`mysql_library_init()': mysql-library-init.  prior to spawning any
threads, or else use a mutex to protect the call, whether you invoke
*Note `mysql_library_init()': mysql-library-init. or indirectly via
*Note `mysql_init()': mysql-init. This should be done prior to any
other client library call.

To connect to the server, call *Note `mysql_init()': mysql-init. to
initialize a connection handler, then call *Note
`mysql_real_connect()': mysql-real-connect. with that handler (along
with other information such as the host name, user name, and password).
Upon connection, *Note `mysql_real_connect()': mysql-real-connect. sets
the `reconnect' flag (part of the `MYSQL' structure) to a value of `1'
in versions of the API older than 5.0.3, or `0' in newer versions. A
value of `1' for this flag indicates that if a statement cannot be
performed because of a lost connection, to try reconnecting to the
server before giving up. You can use the `MYSQL_OPT_RECONNECT' option to
*Note `mysql_options()': mysql-options. to control reconnection
behavior. When you are done with the connection, call *Note
`mysql_close()': mysql-close. to terminate it.

While a connection is active, the client may send SQL statements to the
server using *Note `mysql_query()': mysql-query.  or *Note
`mysql_real_query()': mysql-real-query. The difference between the two
is that *Note `mysql_query()': mysql-query. expects the query to be
specified as a null-terminated string whereas *Note
`mysql_real_query()': mysql-real-query. expects a counted string. If
the string contains binary data (which may include null bytes), you
must use *Note `mysql_real_query()': mysql-real-query.

For each non-*Note `SELECT': select. query (for example, *Note
`INSERT': insert, *Note `UPDATE': update, *Note `DELETE': delete.), you
can find out how many rows were changed (affected) by calling *Note
`mysql_affected_rows()': mysql-affected-rows.

For *Note `SELECT': select. queries, you retrieve the selected rows as
a result set. (Note that some statements are *Note `SELECT':
select.-like in that they return rows. These include *Note `SHOW': show,
*Note `DESCRIBE': describe, and *Note `EXPLAIN': explain. They should
be treated the same way as *Note `SELECT': select. statements.)

There are two ways for a client to process result sets. One way is to
retrieve the entire result set all at once by calling *Note
`mysql_store_result()': mysql-store-result. This function acquires from
the server all the rows returned by the query and stores them in the
client. The second way is for the client to initiate a row-by-row
result set retrieval by calling *Note `mysql_use_result()':
mysql-use-result. This function initializes the retrieval, but does not
actually get any rows from the server.

In both cases, you access rows by calling *Note `mysql_fetch_row()':
mysql-fetch-row. With *Note `mysql_store_result()': mysql-store-result,
*Note `mysql_fetch_row()': mysql-fetch-row. accesses rows that have
previously been fetched from the server. With *Note
`mysql_use_result()': mysql-use-result, *Note `mysql_fetch_row()':
mysql-fetch-row. actually retrieves the row from the server.
Information about the size of the data in each row is available by
calling *Note `mysql_fetch_lengths()': mysql-fetch-lengths.

After you are done with a result set, call *Note `mysql_free_result()':
mysql-free-result. to free the memory used for it.

The two retrieval mechanisms are complementary. Client programs should
choose the approach that is most appropriate for their requirements. In
practice, clients tend to use *Note `mysql_store_result()':
mysql-store-result. more commonly.

An advantage of *Note `mysql_store_result()': mysql-store-result. is
that because the rows have all been fetched to the client, you not only
can access rows sequentially, you can move back and forth in the result
set using *Note `mysql_data_seek()': mysql-data-seek.  or *Note
`mysql_row_seek()': mysql-row-seek. to change the current row position
within the result set. You can also find out how many rows there are by
calling *Note `mysql_num_rows()': mysql-num-rows. On the other hand,
the memory requirements for *Note `mysql_store_result()':
mysql-store-result. may be very high for large result sets and you are
more likely to encounter out-of-memory conditions.

An advantage of *Note `mysql_use_result()': mysql-use-result.  is that
the client requires less memory for the result set because it maintains
only one row at a time (and because there is less allocation overhead,
*Note `mysql_use_result()': mysql-use-result. can be faster).
Disadvantages are that you must process each row quickly to avoid tying
up the server, you don't have random access to rows within the result
set (you can only access rows sequentially), and you don't know how
many rows are in the result set until you have retrieved them all.
Furthermore, you *must* retrieve all the rows even if you determine in
mid-retrieval that you've found the information you were looking for.

The API makes it possible for clients to respond appropriately to
statements (retrieving rows only as necessary) without knowing whether
the statement is a *Note `SELECT': select.  You can do this by calling
*Note `mysql_store_result()': mysql-store-result. after each *Note
`mysql_query()': mysql-query. (or *Note `mysql_real_query()':
mysql-real-query.). If the result set call succeeds, the statement was a
*Note `SELECT': select. and you can read the rows.  If the result set
call fails, call *Note `mysql_field_count()': mysql-field-count. to
determine whether a result was actually to be expected. If *Note
`mysql_field_count()': mysql-field-count. returns zero, the statement
returned no data (indicating that it was an *Note `INSERT': insert,
*Note `UPDATE': update, *Note `DELETE': delete, and so forth), and was
not expected to return rows. If *Note `mysql_field_count()':
mysql-field-count. is non-zero, the statement should have returned
rows, but didn't. This indicates that the statement was a *Note
`SELECT': select. that failed. See the description for *Note
`mysql_field_count()': mysql-field-count. for an example of how this
can be done.

Both *Note `mysql_store_result()': mysql-store-result. and *Note
`mysql_use_result()': mysql-use-result. allow you to obtain information
about the fields that make up the result set (the number of fields,
their names and types, and so forth). You can access field information
sequentially within the row by calling *Note `mysql_fetch_field()':
mysql-fetch-field.  repeatedly, or by field number within the row by
calling *Note `mysql_fetch_field_direct()': mysql-fetch-field-direct.
The current field cursor position may be changed by calling *Note
`mysql_field_seek()': mysql-field-seek. Setting the field cursor
affects subsequent calls to *Note `mysql_fetch_field()':
mysql-fetch-field. You can also get information for fields all at once
by calling *Note `mysql_fetch_fields()': mysql-fetch-fields.

For detecting and reporting errors, MySQL provides access to error
information by means of the *Note `mysql_errno()': mysql-errno. and
*Note `mysql_error()': mysql-error. functions. These return the error
code or error message for the most recently invoked function that can
succeed or fail, allowing you to determine when an error occurred and
what it was.


File: manual.info,  Node: c-api-functions,  Next: c-api-prepared-statements,  Prev: c-api-function-overview,  Up: c

20.10.3 C API Function Descriptions
-----------------------------------

* Menu:

* mysql-affected-rows::          `mysql_affected_rows()'
* mysql-autocommit::             `mysql_autocommit()'
* mysql-change-user::            `mysql_change_user()'
* mysql-character-set-name::     `mysql_character_set_name()'
* mysql-close::                  `mysql_close()'
* mysql-commit::                 `mysql_commit()'
* mysql-connect::                `mysql_connect()'
* mysql-create-db::              `mysql_create_db()'
* mysql-data-seek::              `mysql_data_seek()'
* mysql-debug::                  `mysql_debug()'
* mysql-drop-db::                `mysql_drop_db()'
* mysql-dump-debug-info::        `mysql_dump_debug_info()'
* mysql-eof::                    `mysql_eof()'
* mysql-errno::                  `mysql_errno()'
* mysql-error::                  `mysql_error()'
* mysql-escape-string::          `mysql_escape_string()'
* mysql-fetch-field::            `mysql_fetch_field()'
* mysql-fetch-field-direct::     `mysql_fetch_field_direct()'
* mysql-fetch-fields::           `mysql_fetch_fields()'
* mysql-fetch-lengths::          `mysql_fetch_lengths()'
* mysql-fetch-row::              `mysql_fetch_row()'
* mysql-field-count::            `mysql_field_count()'
* mysql-field-seek::             `mysql_field_seek()'
* mysql-field-tell::             `mysql_field_tell()'
* mysql-free-result::            `mysql_free_result()'
* mysql-get-character-set-info::  `mysql_get_character_set_info()'
* mysql-get-client-info::        `mysql_get_client_info()'
* mysql-get-client-version::     `mysql_get_client_version()'
* mysql-get-host-info::          `mysql_get_host_info()'
* mysql-get-proto-info::         `mysql_get_proto_info()'
* mysql-get-server-info::        `mysql_get_server_info()'
* mysql-get-server-version::     `mysql_get_server_version()'
* mysql-get-ssl-cipher::         `mysql_get_ssl_cipher()'
* mysql-hex-string::             `mysql_hex_string()'
* mysql-info::                   `mysql_info()'
* mysql-init::                   `mysql_init()'
* mysql-insert-id::              `mysql_insert_id()'
* mysql-kill::                   `mysql_kill()'
* mysql-library-end::            `mysql_library_end()'
* mysql-library-init::           `mysql_library_init()'
* mysql-list-dbs::               `mysql_list_dbs()'
* mysql-list-fields::            `mysql_list_fields()'
* mysql-list-processes::         `mysql_list_processes()'
* mysql-list-tables::            `mysql_list_tables()'
* mysql-more-results::           `mysql_more_results()'
* mysql-next-result::            `mysql_next_result()'
* mysql-num-fields::             `mysql_num_fields()'
* mysql-num-rows::               `mysql_num_rows()'
* mysql-options::                `mysql_options()'
* mysql-ping::                   `mysql_ping()'
* mysql-query::                  `mysql_query()'
* mysql-real-connect::           `mysql_real_connect()'
* mysql-real-escape-string::     `mysql_real_escape_string()'
* mysql-real-query::             `mysql_real_query()'
* mysql-refresh::                `mysql_refresh()'
* mysql-reload::                 `mysql_reload()'
* mysql-rollback::               `mysql_rollback()'
* mysql-row-seek::               `mysql_row_seek()'
* mysql-row-tell::               `mysql_row_tell()'
* mysql-select-db::              `mysql_select_db()'
* mysql-set-character-set::      `mysql_set_character_set()'
* mysql-set-local-infile-default::  `mysql_set_local_infile_default()'
* mysql-set-local-infile-handler::  `mysql_set_local_infile_handler()'
* mysql-set-server-option::      `mysql_set_server_option()'
* mysql-shutdown::               `mysql_shutdown()'
* mysql-sqlstate::               `mysql_sqlstate()'
* mysql-ssl-set::                `mysql_ssl_set()'
* mysql-stat::                   `mysql_stat()'
* mysql-store-result::           `mysql_store_result()'
* mysql-thread-id::              `mysql_thread_id()'
* mysql-use-result::             `mysql_use_result()'
* mysql-warning-count::          `mysql_warning_count()'

In the descriptions here, a parameter or return value of `NULL' means
`NULL' in the sense of the C programming language, not a MySQL `NULL'
value.

Functions that return a value generally return a pointer or an integer.
Unless specified otherwise, functions returning a pointer return a
non-`NULL' value to indicate success or a `NULL' value to indicate an
error, and functions returning an integer return zero to indicate
success or non-zero to indicate an error. Note that `non-zero' means
just that. Unless the function description says otherwise, do not test
against a value other than zero:

     if (result)                   /* correct */
         ... error ...

     if (result < 0)               /* incorrect */
         ... error ...

     if (result == -1)             /* incorrect */
         ... error ...

When a function returns an error, the *Errors* subsection of the
function description lists the possible types of errors. You can find
out which of these occurred by calling *Note `mysql_errno()':
mysql-errno. A string representation of the error may be obtained by
calling *Note `mysql_error()': mysql-error.


File: manual.info,  Node: mysql-affected-rows,  Next: mysql-autocommit,  Prev: c-api-functions,  Up: c-api-functions

20.10.3.1 `mysql_affected_rows()'
.................................

`my_ulonglong mysql_affected_rows(MYSQL *mysql)'

*Description*

After executing a statement with *Note `mysql_query()': mysql-query. or
*Note `mysql_real_query()': mysql-real-query, returns the number of
rows changed (for *Note `UPDATE': update.), deleted (for *Note
`DELETE': delete.), or inserted (for *Note `INSERT': insert.). For
*Note `SELECT': select. statements, *Note `mysql_affected_rows()':
mysql-affected-rows. works like *Note `mysql_num_rows()':
mysql-num-rows.

*Return Values*

An integer greater than zero indicates the number of rows affected or
retrieved. Zero indicates that no records were updated for an *Note
`UPDATE': update. statement, no rows matched the `WHERE' clause in the
query or that no query has yet been executed. -1 indicates that the
query returned an error or that, for a *Note `SELECT': select. query,
*Note `mysql_affected_rows()': mysql-affected-rows. was called prior to
calling *Note `mysql_store_result()': mysql-store-result. Because *Note
`mysql_affected_rows()': mysql-affected-rows. returns an unsigned
value, you can check for -1 by comparing the return value to
`(my_ulonglong)-1' (or to `(my_ulonglong)~0', which is equivalent).

*Errors*

None.

*Example*

     char *stmt = "UPDATE products SET cost=cost*1.25 WHERE group=10";
     mysql_query(&mysql,stmt);
     printf("%ld products updated",
            (long) mysql_affected_rows(&mysql));

For *Note `UPDATE': update. statements, if you specify the
`CLIENT_FOUND_ROWS' flag when connecting to *Note `mysqld': mysqld,
*Note `mysql_affected_rows()': mysql-affected-rows. returns the number
of rows matched by the `WHERE' clause. Otherwise, the default behavior
is to return the number of rows actually changed.

Note that when you use a *Note `REPLACE': replace.  command, *Note
`mysql_affected_rows()': mysql-affected-rows.  returns 2 if the new row
replaced an old row, because in this case, one row was inserted after
the duplicate was deleted.

If you use `INSERT ... ON DUPLICATE KEY UPDATE' to insert a row, *Note
`mysql_affected_rows()': mysql-affected-rows. returns 1 if the row is
inserted as a new row and 2 if an existing row is updated.

*Note `mysql_affected_rows()': mysql-affected-rows. returns `0'
following a *Note `CALL': call. statement for a stored procedure that
contains a statement that modifies rows because in this case *Note
`mysql_insert_id()': mysql-insert-id.  applies to *Note `CALL': call.
and not the statement within the procedure. Within the procedure, you
can use `ROW_COUNT()' at the SQL level to obtain the `AUTO_INCREMENT'
value.


File: manual.info,  Node: mysql-autocommit,  Next: mysql-change-user,  Prev: mysql-affected-rows,  Up: c-api-functions

20.10.3.2 `mysql_autocommit()'
..............................

`my_bool mysql_autocommit(MYSQL *mysql, my_bool mode)'

*Description*

Sets autocommit mode on if `mode' is 1, off if `mode' is 0.

*Return Values*

Zero if successful. Non-zero if an error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-change-user,  Next: mysql-character-set-name,  Prev: mysql-autocommit,  Up: c-api-functions

20.10.3.3 `mysql_change_user()'
...............................

`my_bool mysql_change_user(MYSQL *mysql, const char *user, const char
*password, const char *db)'

*Description*

Changes the user and causes the database specified by `db' to become
the default (current) database on the connection specified by `mysql'.
In subsequent queries, this database is the default for table
references that do not include an explicit database specifier.

*Note `mysql_change_user()': mysql-change-user. fails if the connected
user cannot be authenticated or doesn't have permission to use the
database. In this case, the user and database are not changed.

The `db' parameter may be set to `NULL' if you don't want to have a
default database.

This command resets the state as if one had done a new connect.  (See
*Note auto-reconnect::.) It always performs a *Note `ROLLBACK': commit.
of any active transactions, closes and drops all temporary tables, and
unlocks all locked tables. Session system variables are reset to the
values of the corresponding global system variables. Prepared
statements are released and *Note `HANDLER': handler. variables are
closed.  Locks acquired with `GET_LOCK()' are released. These effects
occur even if the user didn't change.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

The same that you can get from *Note `mysql_real_connect()':
mysql-real-connect.

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

   * `ER_UNKNOWN_COM_ERROR'

     The MySQL server doesn't implement this command (probably an old
     server).

   * `ER_ACCESS_DENIED_ERROR'

     The user or password was wrong.

   * `ER_BAD_DB_ERROR'

     The database didn't exist.

   * `ER_DBACCESS_DENIED_ERROR'

     The user did not have access rights to the database.

   * `ER_WRONG_DB_NAME'

     The database name was too long.

*Example*

     if (mysql_change_user(&mysql, "user", "password", "new_database"))
     {
        fprintf(stderr, "Failed to change user.  Error: %s\n",
                mysql_error(&mysql));
     }


File: manual.info,  Node: mysql-character-set-name,  Next: mysql-close,  Prev: mysql-change-user,  Up: c-api-functions

20.10.3.4 `mysql_character_set_name()'
......................................

`const char *mysql_character_set_name(MYSQL *mysql)'

*Description*

Returns the default character set name for the current connection.

*Return Values*

The default character set name

*Errors*

None.


File: manual.info,  Node: mysql-close,  Next: mysql-commit,  Prev: mysql-character-set-name,  Up: c-api-functions

20.10.3.5 `mysql_close()'
.........................

`void mysql_close(MYSQL *mysql)'

*Description*

Closes a previously opened connection.  *Note `mysql_close()':
mysql-close. also deallocates the connection handle pointed to by
`mysql' if the handle was allocated automatically by *Note
`mysql_init()': mysql-init. or *Note `mysql_connect()': mysql-connect.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-commit,  Next: mysql-connect,  Prev: mysql-close,  Up: c-api-functions

20.10.3.6 `mysql_commit()'
..........................

`my_bool mysql_commit(MYSQL *mysql)'

*Description*

Commits the current transaction.

The action of this function is subject to the value of the
`completion_type' system variable. In particular, if the value of
`completion_type' is 2, the server performs a release after terminating
a transaction and closes the client connection. The client program
should call *Note `mysql_close()': mysql-close. to close the connection
from the client side.

*Return Values*

Zero if successful. Non-zero if an error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-connect,  Next: mysql-create-db,  Prev: mysql-commit,  Up: c-api-functions

20.10.3.7 `mysql_connect()'
...........................

`MYSQL *mysql_connect(MYSQL *mysql, const char *host, const char *user,
const char *passwd)'

*Description*

This function is deprecated. Use *Note `mysql_real_connect()':
mysql-real-connect. instead.

*Note `mysql_connect()': mysql-connect. attempts to establish a
connection to a MySQL database engine running on `host'.  *Note
`mysql_connect()': mysql-connect. must complete successfully before you
can execute any of the other API functions, with the exception of *Note
`mysql_get_client_info()': mysql-get-client-info.

The meanings of the parameters are the same as for the corresponding
parameters for *Note `mysql_real_connect()': mysql-real-connect. with
the difference that the connection parameter may be `NULL'. In this
case, the C API allocates memory for the connection structure
automatically and frees it when you call *Note `mysql_close()':
mysql-close. The disadvantage of this approach is that you can't
retrieve an error message if the connection fails. (To get error
information from *Note `mysql_errno()': mysql-errno. or *Note
`mysql_error()': mysql-error, you must provide a valid `MYSQL' pointer.)

*Return Values*

Same as for *Note `mysql_real_connect()': mysql-real-connect.

*Errors*

Same as for *Note `mysql_real_connect()': mysql-real-connect.


File: manual.info,  Node: mysql-create-db,  Next: mysql-data-seek,  Prev: mysql-connect,  Up: c-api-functions

20.10.3.8 `mysql_create_db()'
.............................

`int mysql_create_db(MYSQL *mysql, const char *db)'

*Description*

Creates the database named by the `db' parameter.

This function is deprecated. It is preferable to use *Note
`mysql_query()': mysql-query. to issue an SQL *Note `CREATE DATABASE':
create-database. statement instead.

*Return Values*

Zero if the database was created successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

     if(mysql_create_db(&mysql, "my_database"))
     {
        fprintf(stderr, "Failed to create new database.  Error: %s\n",
                mysql_error(&mysql));
     }


File: manual.info,  Node: mysql-data-seek,  Next: mysql-debug,  Prev: mysql-create-db,  Up: c-api-functions

20.10.3.9 `mysql_data_seek()'
.............................

`void mysql_data_seek(MYSQL_RES *result, my_ulonglong offset)'

*Description*

Seeks to an arbitrary row in a query result set. The `offset' value is
a row number and should be in the range from `0' to *Note
`mysql_num_rows(result)-1': mysql-num-rows.

This function requires that the result set structure contains the
entire result of the query, so *Note `mysql_data_seek()':
mysql-data-seek. may be used only in conjunction with *Note
`mysql_store_result()': mysql-store-result, not with *Note
`mysql_use_result()': mysql-use-result.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-debug,  Next: mysql-drop-db,  Prev: mysql-data-seek,  Up: c-api-functions

20.10.3.10 `mysql_debug()'
..........................

`void mysql_debug(const char *debug)'

*Description*

Does a `DBUG_PUSH' with the given string.  *Note `mysql_debug()':
mysql-debug. uses the Fred Fish debug library. To use this function,
you must compile the client library to support debugging. See MySQL
Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).

*Return Values*

None.

*Errors*

None.

*Example*

The call shown here causes the client library to generate a trace file
in `/tmp/client.trace' on the client machine:

     mysql_debug("d:t:O,/tmp/client.trace");


File: manual.info,  Node: mysql-drop-db,  Next: mysql-dump-debug-info,  Prev: mysql-debug,  Up: c-api-functions

20.10.3.11 `mysql_drop_db()'
............................

`int mysql_drop_db(MYSQL *mysql, const char *db)'

*Description*

Drops the database named by the `db' parameter.

This function is deprecated. It is preferable to use *Note
`mysql_query()': mysql-query. to issue an SQL *Note `DROP DATABASE':
drop-database. statement instead.

*Return Values*

Zero if the database was dropped successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

     if(mysql_drop_db(&mysql, "my_database"))
       fprintf(stderr, "Failed to drop the database: Error: %s\n",
               mysql_error(&mysql));


File: manual.info,  Node: mysql-dump-debug-info,  Next: mysql-eof,  Prev: mysql-drop-db,  Up: c-api-functions

20.10.3.12 `mysql_dump_debug_info()'
....................................

`int mysql_dump_debug_info(MYSQL *mysql)'

*Description*

Instructs the server to write some debug information to the log.  For
this to work, the connected user must have the `SUPER' privilege.

*Return Values*

Zero if the command was successful. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-eof,  Next: mysql-errno,  Prev: mysql-dump-debug-info,  Up: c-api-functions

20.10.3.13 `mysql_eof()'
........................

`my_bool mysql_eof(MYSQL_RES *result)'

*Description*

This function is deprecated.  *Note `mysql_errno()': mysql-errno. or
*Note `mysql_error()': mysql-error. may be used instead.

*Note `mysql_eof()': mysql-eof. determines whether the last row of a
result set has been read.

If you acquire a result set from a successful call to *Note
`mysql_store_result()': mysql-store-result, the client receives the
entire set in one operation. In this case, a `NULL' return from *Note
`mysql_fetch_row()': mysql-fetch-row. always means the end of the
result set has been reached and it is unnecessary to call *Note
`mysql_eof()': mysql-eof. When used with *Note `mysql_store_result()':
mysql-store-result, *Note `mysql_eof()': mysql-eof. always returns true.

On the other hand, if you use *Note `mysql_use_result()':
mysql-use-result. to initiate a result set retrieval, the rows of the
set are obtained from the server one by one as you call *Note
`mysql_fetch_row()': mysql-fetch-row. repeatedly.  Because an error may
occur on the connection during this process, a `NULL' return value from
*Note `mysql_fetch_row()': mysql-fetch-row. does not necessarily mean
the end of the result set was reached normally.  In this case, you can
use *Note `mysql_eof()': mysql-eof. to determine what happened. *Note
`mysql_eof()': mysql-eof. returns a non-zero value if the end of the
result set was reached and zero if an error occurred.

Historically, *Note `mysql_eof()': mysql-eof.  predates the standard
MySQL error functions *Note `mysql_errno()': mysql-errno. and *Note
`mysql_error()': mysql-error. Because those error functions provide the
same information, their use is preferred over *Note `mysql_eof()':
mysql-eof, which is deprecated. (In fact, they provide more information,
because *Note `mysql_eof()': mysql-eof. returns only a boolean value
whereas the error functions indicate a reason for the error when one
occurs.)

*Return Values*

Zero if no error occurred. Non-zero if the end of the result set has
been reached.

*Errors*

None.

*Example*

The following example shows how you might use *Note `mysql_eof()':
mysql-eof.:

     mysql_query(&mysql,"SELECT * FROM some_table");
     result = mysql_use_result(&mysql);
     while((row = mysql_fetch_row(result)))
     {
         // do something with data
     }
     if(!mysql_eof(result))  // mysql_fetch_row() failed due to an error
     {
         fprintf(stderr, "Error: %s\n", mysql_error(&mysql));
     }

However, you can achieve the same effect with the standard MySQL error
functions:

     mysql_query(&mysql,"SELECT * FROM some_table");
     result = mysql_use_result(&mysql);
     while((row = mysql_fetch_row(result)))
     {
         // do something with data
     }
     if(mysql_errno(&mysql))  // mysql_fetch_row() failed due to an error
     {
         fprintf(stderr, "Error: %s\n", mysql_error(&mysql));
     }


File: manual.info,  Node: mysql-errno,  Next: mysql-error,  Prev: mysql-eof,  Up: c-api-functions

20.10.3.14 `mysql_errno()'
..........................

`unsigned int mysql_errno(MYSQL *mysql)'

*Description*

For the connection specified by `mysql', *Note `mysql_errno()':
mysql-errno. returns the error code for the most recently invoked API
function that can succeed or fail. A return value of zero means that no
error occurred.  Client error message numbers are listed in the MySQL
`errmsg.h' header file. Server error message numbers are listed in
`mysqld_error.h'.  Errors also are listed at *Note error-handling::.

Note that some functions like *Note `mysql_fetch_row()':
mysql-fetch-row. don't set *Note `mysql_errno()': mysql-errno. if they
succeed.

A rule of thumb is that all functions that have to ask the server for
information reset *Note `mysql_errno()': mysql-errno. if they succeed.

MySQL-specific error numbers returned by *Note `mysql_errno()':
mysql-errno. differ from SQLSTATE values returned by *Note
`mysql_sqlstate()': mysql-sqlstate. For example, the *Note `mysql':
mysql. client program displays errors using the following format, where
`1146' is the *Note `mysql_errno()': mysql-errno. value and `'42S02''
is the corresponding *Note `mysql_sqlstate()': mysql-sqlstate. value:

     shell> SELECT * FROM no_such_table;
     ERROR 1146 (42S02): Table 'test.no_such_table' doesn't exist

*Return Values*

An error code value for the last `mysql_XXX()' call, if it failed. zero
means no error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-error,  Next: mysql-escape-string,  Prev: mysql-errno,  Up: c-api-functions

20.10.3.15 `mysql_error()'
..........................

`const char *mysql_error(MYSQL *mysql)'

*Description*

For the connection specified by `mysql', *Note `mysql_error()':
mysql-error. returns a null-terminated string containing the error
message for the most recently invoked API function that failed. If a
function didn't fail, the return value of *Note `mysql_error()':
mysql-error. may be the previous error or an empty string to indicate
no error.

A rule of thumb is that all functions that have to ask the server for
information reset *Note `mysql_error()': mysql-error. if they succeed.

For functions that reset *Note `mysql_error()': mysql-error, the
following two tests are equivalent:

     if(*mysql_error(&mysql))
     {
       // an error occurred
     }

     if(mysql_error(&mysql)[0])
     {
       // an error occurred
     }

The language of the client error messages may be changed by recompiling
the MySQL client library. Currently, you can choose error messages in
several different languages. See *Note error-message-language::.

*Return Values*

A null-terminated character string that describes the error. An empty
string if no error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-escape-string,  Next: mysql-fetch-field,  Prev: mysql-error,  Up: c-api-functions

20.10.3.16 `mysql_escape_string()'
..................................

You should use *Note `mysql_real_escape_string()':
mysql-real-escape-string.  instead!

This function is identical to *Note `mysql_real_escape_string()':
mysql-real-escape-string.  except that *Note
`mysql_real_escape_string()': mysql-real-escape-string. takes a
connection handler as its first argument and escapes the string
according to the current character set.  *Note `mysql_escape_string()':
mysql-escape-string. does not take a connection argument and does not
respect the current character set.


File: manual.info,  Node: mysql-fetch-field,  Next: mysql-fetch-field-direct,  Prev: mysql-escape-string,  Up: c-api-functions

20.10.3.17 `mysql_fetch_field()'
................................

`MYSQL_FIELD *mysql_fetch_field(MYSQL_RES *result)'

*Description*

Returns the definition of one column of a result set as a `MYSQL_FIELD'
structure. Call this function repeatedly to retrieve information about
all columns in the result set. *Note `mysql_fetch_field()':
mysql-fetch-field.  returns `NULL' when no more fields are left.

*Note `mysql_fetch_field()': mysql-fetch-field. is reset to return
information about the first field each time you execute a new *Note
`SELECT': select. query. The field returned by *Note
`mysql_fetch_field()': mysql-fetch-field.  is also affected by calls to
*Note `mysql_field_seek()': mysql-field-seek.

If you've called *Note `mysql_query()': mysql-query.  to perform a
*Note `SELECT': select. on a table but have not called *Note
`mysql_store_result()': mysql-store-result, MySQL returns the default
blob length (8KB) if you call *Note `mysql_fetch_field()':
mysql-fetch-field. to ask for the length of a *Note `BLOB': blob.
field. (The 8KB size is chosen because MySQL doesn't know the maximum
length for the *Note `BLOB': blob. This should be made configurable
sometime.) Once you've retrieved the result set, `field->max_length'
contains the length of the largest value for this column in the
specific query.

*Return Values*

The `MYSQL_FIELD' structure for the current column. `NULL' if no
columns are left.

*Errors*

None.

*Example*

     MYSQL_FIELD *field;

     while((field = mysql_fetch_field(result)))
     {
         printf("field name %s\n", field->name);
     }


File: manual.info,  Node: mysql-fetch-field-direct,  Next: mysql-fetch-fields,  Prev: mysql-fetch-field,  Up: c-api-functions

20.10.3.18 `mysql_fetch_field_direct()'
.......................................

`MYSQL_FIELD *mysql_fetch_field_direct(MYSQL_RES *result, unsigned int
fieldnr)'

*Description*

Given a field number `fieldnr' for a column within a result set,
returns that column's field definition as a `MYSQL_FIELD' structure.
You may use this function to retrieve the definition for an arbitrary
column. The value of `fieldnr' should be in the range from 0 to *Note
`mysql_num_fields(result)-1': mysql-num-fields.

*Return Values*

The `MYSQL_FIELD' structure for the specified column.

*Errors*

None.

*Example*

     unsigned int num_fields;
     unsigned int i;
     MYSQL_FIELD *field;

     num_fields = mysql_num_fields(result);
     for(i = 0; i < num_fields; i++)
     {
         field = mysql_fetch_field_direct(result, i);
         printf("Field %u is %s\n", i, field->name);
     }


File: manual.info,  Node: mysql-fetch-fields,  Next: mysql-fetch-lengths,  Prev: mysql-fetch-field-direct,  Up: c-api-functions

20.10.3.19 `mysql_fetch_fields()'
.................................

`MYSQL_FIELD *mysql_fetch_fields(MYSQL_RES *result)'

*Description*

Returns an array of all `MYSQL_FIELD' structures for a result set. Each
structure provides the field definition for one column of the result
set.

*Return Values*

An array of `MYSQL_FIELD' structures for all columns of a result set.

*Errors*

None.

*Example*

     unsigned int num_fields;
     unsigned int i;
     MYSQL_FIELD *fields;

     num_fields = mysql_num_fields(result);
     fields = mysql_fetch_fields(result);
     for(i = 0; i < num_fields; i++)
     {
        printf("Field %u is %s\n", i, fields[i].name);
     }


File: manual.info,  Node: mysql-fetch-lengths,  Next: mysql-fetch-row,  Prev: mysql-fetch-fields,  Up: c-api-functions

20.10.3.20 `mysql_fetch_lengths()'
..................................

`unsigned long *mysql_fetch_lengths(MYSQL_RES *result)'

*Description*

Returns the lengths of the columns of the current row within a result
set. If you plan to copy field values, this length information is also
useful for optimization, because you can avoid calling `strlen()'. In
addition, if the result set contains binary data, you *must* use this
function to determine the size of the data, because `strlen()' returns
incorrect results for any field containing null characters.

The length for empty columns and for columns containing `NULL' values
is zero. To see how to distinguish these two cases, see the description
for *Note `mysql_fetch_row()': mysql-fetch-row.

*Return Values*

An array of unsigned long integers representing the size of each column
(not including any terminating null characters).  `NULL' if an error
occurred.

*Errors*

*Note `mysql_fetch_lengths()': mysql-fetch-lengths. is valid only for
the current row of the result set. It returns `NULL' if you call it
before calling *Note `mysql_fetch_row()': mysql-fetch-row. or after
retrieving all rows in the result.

*Example*

     MYSQL_ROW row;
     unsigned long *lengths;
     unsigned int num_fields;
     unsigned int i;

     row = mysql_fetch_row(result);
     if (row)
     {
         num_fields = mysql_num_fields(result);
         lengths = mysql_fetch_lengths(result);
         for(i = 0; i < num_fields; i++)
         {
              printf("Column %u is %lu bytes in length.\n",
                     i, lengths[i]);
         }
     }


File: manual.info,  Node: mysql-fetch-row,  Next: mysql-field-count,  Prev: mysql-fetch-lengths,  Up: c-api-functions

20.10.3.21 `mysql_fetch_row()'
..............................

`MYSQL_ROW mysql_fetch_row(MYSQL_RES *result)'

*Description*

Retrieves the next row of a result set. When used after *Note
`mysql_store_result()': mysql-store-result, *Note `mysql_fetch_row()':
mysql-fetch-row. returns `NULL' when there are no more rows to retrieve.
When used after *Note `mysql_use_result()': mysql-use-result, *Note
`mysql_fetch_row()': mysql-fetch-row. returns `NULL' when there are no
more rows to retrieve or if an error occurred.

The number of values in the row is given by *Note
`mysql_num_fields(result)': mysql-num-fields. If `row' holds the return
value from a call to *Note `mysql_fetch_row()': mysql-fetch-row,
pointers to the values are accessed as `row[0]' to
`row[mysql_num_fields(result)-1]'.  `NULL' values in the row are
indicated by `NULL' pointers.

The lengths of the field values in the row may be obtained by calling
*Note `mysql_fetch_lengths()': mysql-fetch-lengths.  Empty fields and
fields containing `NULL' both have length 0; you can distinguish these
by checking the pointer for the field value. If the pointer is `NULL',
the field is `NULL'; otherwise, the field is empty.

*Return Values*

A `MYSQL_ROW' structure for the next row.  `NULL' if there are no more
rows to retrieve or if an error occurred.

*Errors*

Note that error is not reset between calls to *Note
`mysql_fetch_row()': mysql-fetch-row.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

     MYSQL_ROW row;
     unsigned int num_fields;
     unsigned int i;

     num_fields = mysql_num_fields(result);
     while ((row = mysql_fetch_row(result)))
     {
        unsigned long *lengths;
        lengths = mysql_fetch_lengths(result);
        for(i = 0; i < num_fields; i++)
        {
            printf("[%.*s] ", (int) lengths[i],
                   row[i] ? row[i] : "NULL");
        }
        printf("\n");
     }


File: manual.info,  Node: mysql-field-count,  Next: mysql-field-seek,  Prev: mysql-fetch-row,  Up: c-api-functions

20.10.3.22 `mysql_field_count()'
................................

`unsigned int mysql_field_count(MYSQL *mysql)'

*Description*

Returns the number of columns for the most recent query on the
connection.

The normal use of this function is when *Note `mysql_store_result()':
mysql-store-result. returned `NULL' (and thus you have no result set
pointer). In this case, you can call *Note `mysql_field_count()':
mysql-field-count. to determine whether *Note `mysql_store_result()':
mysql-store-result.  should have produced a non-empty result. This
allows the client program to take proper action without knowing whether
the query was a *Note `SELECT': select. (or *Note `SELECT':
select.-like) statement. The example shown here illustrates how this
may be done.

See *Note null-mysql-store-result::.

*Return Values*

An unsigned integer representing the number of columns in a result set.

*Errors*

None.

*Example*

     MYSQL_RES *result;
     unsigned int num_fields;
     unsigned int num_rows;

     if (mysql_query(&mysql,query_string))
     {
         // error
     }
     else // query succeeded, process any data returned by it
     {
         result = mysql_store_result(&mysql);
         if (result)  // there are rows
         {
             num_fields = mysql_num_fields(result);
             // retrieve rows, then call mysql_free_result(result)
         }
         else  // mysql_store_result() returned nothing; should it have?
         {
             if(mysql_field_count(&mysql) == 0)
             {
                 // query does not return data
                 // (it was not a SELECT)
                 num_rows = mysql_affected_rows(&mysql);
             }
             else // mysql_store_result() should have returned data
             {
                 fprintf(stderr, "Error: %s\n", mysql_error(&mysql));
             }
         }
     }

An alternative is to replace the *Note `mysql_field_count(&mysql)':
mysql-field-count.  call with *Note `mysql_errno(&mysql)': mysql-errno.
In this case, you are checking directly for an error from *Note
`mysql_store_result()': mysql-store-result. rather than inferring from
the value of *Note `mysql_field_count()': mysql-field-count. whether the
statement was a *Note `SELECT': select.


File: manual.info,  Node: mysql-field-seek,  Next: mysql-field-tell,  Prev: mysql-field-count,  Up: c-api-functions

20.10.3.23 `mysql_field_seek()'
...............................

`MYSQL_FIELD_OFFSET mysql_field_seek(MYSQL_RES *result,
MYSQL_FIELD_OFFSET offset)'

*Description*

Sets the field cursor to the given offset. The next call to *Note
`mysql_fetch_field()': mysql-fetch-field. retrieves the field
definition of the column associated with that offset.

To seek to the beginning of a row, pass an `offset' value of zero.

*Return Values*

The previous value of the field cursor.

*Errors*

None.


File: manual.info,  Node: mysql-field-tell,  Next: mysql-free-result,  Prev: mysql-field-seek,  Up: c-api-functions

20.10.3.24 `mysql_field_tell()'
...............................

`MYSQL_FIELD_OFFSET mysql_field_tell(MYSQL_RES *result)'

*Description*

Returns the position of the field cursor used for the last *Note
`mysql_fetch_field()': mysql-fetch-field. This value can be used as an
argument to *Note `mysql_field_seek()': mysql-field-seek.

*Return Values*

The current offset of the field cursor.

*Errors*

None.


File: manual.info,  Node: mysql-free-result,  Next: mysql-get-character-set-info,  Prev: mysql-field-tell,  Up: c-api-functions

20.10.3.25 `mysql_free_result()'
................................

`void mysql_free_result(MYSQL_RES *result)'

*Description*

Frees the memory allocated for a result set by *Note
`mysql_store_result()': mysql-store-result, *Note `mysql_use_result()':
mysql-use-result, *Note `mysql_list_dbs()': mysql-list-dbs, and so
forth.  When you are done with a result set, you must free the memory it
uses by calling *Note `mysql_free_result()': mysql-free-result.

Do not attempt to access a result set after freeing it.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-get-character-set-info,  Next: mysql-get-client-info,  Prev: mysql-free-result,  Up: c-api-functions

20.10.3.26 `mysql_get_character_set_info()'
...........................................

`void mysql_get_character_set_info(MYSQL *mysql, MY_CHARSET_INFO *cs)'

*Description*

This function provides information about the default client character
set. The default character set may be changed with the *Note
`mysql_set_character_set()': mysql-set-character-set.  function.

*Example*

This example shows the fields that are available in the
`MY_CHARSET_INFO' structure:

     if (!mysql_set_character_set(&mysql, "utf8"))
     {
         MY_CHARSET_INFO cs;
         mysql_get_character_set_info(&mysql, &cs);
         printf("character set information:\n");
         printf("character set+collation number: %d\n", cs.number);
         printf("character set name: %s\n", cs.name);
         printf("collation name: %s\n", cs.csname);
         printf("comment: %s\n", cs.comment);
         printf("directory: %s\n", cs.dir);
         printf("multi byte character min. length: %d\n", cs.mbminlen);
         printf("multi byte character max. length: %d\n", cs.mbmaxlen);
     }


File: manual.info,  Node: mysql-get-client-info,  Next: mysql-get-client-version,  Prev: mysql-get-character-set-info,  Up: c-api-functions

20.10.3.27 `mysql_get_client_info()'
....................................

`const char *mysql_get_client_info(void)'

*Description*

Returns a string that represents the client library version.

*Return Values*

A character string that represents the MySQL client library version.

*Errors*

None.


File: manual.info,  Node: mysql-get-client-version,  Next: mysql-get-host-info,  Prev: mysql-get-client-info,  Up: c-api-functions

20.10.3.28 `mysql_get_client_version()'
.......................................

`unsigned long mysql_get_client_version(void)'

*Description*

Returns an integer that represents the client library version.  The
value has the format `XYYZZ' where `X' is the major version, `YY' is
the release level, and `ZZ' is the version number within the release
level. For example, a value of `40102' represents a client library
version of `4.1.2'.

*Return Values*

An integer that represents the MySQL client library version.

*Errors*

None.


File: manual.info,  Node: mysql-get-host-info,  Next: mysql-get-proto-info,  Prev: mysql-get-client-version,  Up: c-api-functions

20.10.3.29 `mysql_get_host_info()'
..................................

`const char *mysql_get_host_info(MYSQL *mysql)'

*Description*

Returns a string describing the type of connection in use, including
the server host name.

*Return Values*

A character string representing the server host name and the connection
type.

*Errors*

None.


File: manual.info,  Node: mysql-get-proto-info,  Next: mysql-get-server-info,  Prev: mysql-get-host-info,  Up: c-api-functions

20.10.3.30 `mysql_get_proto_info()'
...................................

`unsigned int mysql_get_proto_info(MYSQL *mysql)'

*Description*

Returns the protocol version used by current connection.

*Return Values*

An unsigned integer representing the protocol version used by the
current connection.

*Errors*

None.


File: manual.info,  Node: mysql-get-server-info,  Next: mysql-get-server-version,  Prev: mysql-get-proto-info,  Up: c-api-functions

20.10.3.31 `mysql_get_server_info()'
....................................

`const char *mysql_get_server_info(MYSQL *mysql)'

*Description*

Returns a string that represents the server version number.

*Return Values*

A character string that represents the server version number.

*Errors*

None.


File: manual.info,  Node: mysql-get-server-version,  Next: mysql-get-ssl-cipher,  Prev: mysql-get-server-info,  Up: c-api-functions

20.10.3.32 `mysql_get_server_version()'
.......................................

`unsigned long mysql_get_server_version(MYSQL *mysql)'

*Description*

Returns the version number of the server as an integer.

*Return Values*

A number that represents the MySQL server version in this format:

     major_version*10000 + minor_version *100 + sub_version

For example, 5.1.5 is returned as 50105.

This function is useful in client programs for quickly determining
whether some version-specific server capability exists.

*Errors*

None.


File: manual.info,  Node: mysql-get-ssl-cipher,  Next: mysql-hex-string,  Prev: mysql-get-server-version,  Up: c-api-functions

20.10.3.33 `mysql_get_ssl_cipher()'
...................................

`const char *mysql_get_ssl_cipher(MYSQL *mysql)'

*Description*

*Note `mysql_get_ssl_cipher()': mysql-get-ssl-cipher. returns the SSL
cipher used for the given connection to the server.  `mysql' is the
connection handler returned from *Note `mysql_init()': mysql-init.

*Return Values*

A string naming the SSL cipher used for the connection, or `NULL' if no
cipher is being used.


File: manual.info,  Node: mysql-hex-string,  Next: mysql-info,  Prev: mysql-get-ssl-cipher,  Up: c-api-functions

20.10.3.34 `mysql_hex_string()'
...............................

`unsigned long mysql_hex_string(char *to, const char *from, unsigned
long length)'

*Description*

This function is used to create a legal SQL string that you can use in
an SQL statement. See *Note string-syntax::.

The string in `from' is encoded to hexadecimal format, with each
character encoded as two hexadecimal digits.  The result is placed in
`to' and a terminating null byte is appended.

The string pointed to by `from' must be `length' bytes long. You must
allocate the `to' buffer to be at least `length*2+1' bytes long. When
*Note `mysql_hex_string()': mysql-hex-string. returns, the contents of
`to' is a null-terminated string.  The return value is the length of
the encoded string, not including the terminating null character.

The return value can be placed into an SQL statement using either
`0xVALUE' or `X'VALUE'' format.  However, the return value does not
include the `0x' or `X'...''. The caller must supply whichever of those
is desired.

*Example*

     char query[1000],*end;

     end = strmov(query,"INSERT INTO test_table values(");
     end = strmov(end,"0x");
     end += mysql_hex_string(end,"What is this",12);
     end = strmov(end,",0x");
     end += mysql_hex_string(end,"binary data: \0\r\n",16);
     *end++ = ')';

     if (mysql_real_query(&mysql,query,(unsigned int) (end - query)))
     {
        fprintf(stderr, "Failed to insert row, Error: %s\n",
                mysql_error(&mysql));
     }

The `strmov()' function used in the example is included in the
`mysqlclient' library and works like `strcpy()' but returns a pointer
to the terminating null of the first parameter.

*Return Values*

The length of the value placed into `to', not including the terminating
null character.

*Errors*

None.


File: manual.info,  Node: mysql-info,  Next: mysql-init,  Prev: mysql-hex-string,  Up: c-api-functions

20.10.3.35 `mysql_info()'
.........................

`const char *mysql_info(MYSQL *mysql)'

*Description*

Retrieves a string providing information about the most recently
executed statement, but only for the statements listed here. For other
statements, *Note `mysql_info()': mysql-info.  returns `NULL'. The
format of the string varies depending on the type of statement, as
described here. The numbers are illustrative only; the string contains
values appropriate for the statement.

   * `INSERT INTO ... SELECT ...'

     String format: `Records: 100 Duplicates: 0 Warnings: 0'

   * `INSERT INTO ... VALUES (...),(...),(...)...'

     String format: `Records: 3 Duplicates: 0 Warnings: 0'

   * `LOAD DATA INFILE ...'

     String format: `Records: 1 Deleted: 0 Skipped: 0 Warnings: 0'

   * *Note `ALTER TABLE': alter-table.

     String format: `Records: 3 Duplicates: 0 Warnings: 0'

   * *Note `UPDATE': update.

     String format: `Rows matched: 40 Changed: 40 Warnings: 0'

Note that *Note `mysql_info()': mysql-info. returns a non-`NULL' value
for `INSERT ...  VALUES' only for the multiple-row form of the statement
(that is, only if multiple value lists are specified).

*Return Values*

A character string representing additional information about the most
recently executed statement. `NULL' if no information is available for
the statement.

*Errors*

None.


File: manual.info,  Node: mysql-init,  Next: mysql-insert-id,  Prev: mysql-info,  Up: c-api-functions

20.10.3.36 `mysql_init()'
.........................

`MYSQL *mysql_init(MYSQL *mysql)'

*Description*

Allocates or initializes a `MYSQL' object suitable for *Note
`mysql_real_connect()': mysql-real-connect. If `mysql' is a `NULL'
pointer, the function allocates, initializes, and returns a new object.
Otherwise, the object is initialized and the address of the object is
returned. If *Note `mysql_init()': mysql-init. allocates a new object,
it is freed when *Note `mysql_close()': mysql-close. is called to close
the connection.

*Return Values*

An initialized `MYSQL*' handle.  `NULL' if there was insufficient
memory to allocate a new object.

*Errors*

In case of insufficient memory, `NULL' is returned.


File: manual.info,  Node: mysql-insert-id,  Next: mysql-kill,  Prev: mysql-init,  Up: c-api-functions

20.10.3.37 `mysql_insert_id()'
..............................

`my_ulonglong mysql_insert_id(MYSQL *mysql)'

*Description*

Returns the value generated for an `AUTO_INCREMENT' column by the
previous *Note `INSERT': insert. or *Note `UPDATE': update. statement.
Use this function after you have performed an *Note `INSERT': insert.
statement into a table that contains an `AUTO_INCREMENT' field, or have
used *Note `INSERT': insert. or *Note `UPDATE': update. to set a column
value with `LAST_INSERT_ID(EXPR)'.

The return value of *Note `mysql_insert_id()': mysql-insert-id. is
always zero unless explicitly updated under one of the following
conditions:

   * *Note `INSERT': insert. statements that store a value into an
     `AUTO_INCREMENT' column.  This is true whether the value is
     automatically generated by storing the special values `NULL' or
     `0' into the column, or is an explicit non-special value.

   * In the case of a multiple-row *Note `INSERT': insert. statement,
     the return value of *Note `mysql_insert_id()': mysql-insert-id.
     depends on the MySQL server version.

     *Note `mysql_insert_id()': mysql-insert-id. returns the _first_
     automatically generated `AUTO_INCREMENT' value that was
     _successfully_ inserted.

     If no rows are successfully inserted, *Note `mysql_insert_id()':
     mysql-insert-id. returns 0.

   * If an *Note `INSERT ... SELECT': insert-select. statement is
     executed, and no automatically generated value is successfully
     inserted, *Note `mysql_insert_id()': mysql-insert-id. returns the
     ID of the last inserted row.

   * If an *Note `INSERT ... SELECT': insert-select. statement uses
     `LAST_INSERT_ID(EXPR)', *Note `mysql_insert_id()':
     mysql-insert-id. returns EXPR.

   * *Note `INSERT': insert. statements that generate an
     `AUTO_INCREMENT' value by inserting `LAST_INSERT_ID(EXPR)' into
     any column or by updating any column to `LAST_INSERT_ID(EXPR)'.

   * If the previous statement returned an error, the value of *Note
     `mysql_insert_id()': mysql-insert-id. is undefined.

The return value of *Note `mysql_insert_id()': mysql-insert-id. can be
simplified to the following sequence:

  1. If there is an `AUTO_INCREMENT' column, and an automatically
     generated value was successfully inserted, return the first such
     value.

  2. If `LAST_INSERT_ID(EXPR)' occurred in the statement, return EXPR,
     even if there was an `AUTO_INCREMENT' column in the affected table.

  3. The return value varies depending on the statement used.  When
     called after an *Note `INSERT': insert.  statement:

        * If there is an `AUTO_INCREMENT' column in the table, and
          there were some explicit values for this column that were
          successfully inserted into the table, return the last of the
          explicit values.

     When called after an `INSERT ... ON DUPLICATE KEY' statement:

        * If there is an `AUTO_INCREMENT' column in the table and there
          were some explicit succesfully inserted values, or some
          updated rows, return the last of the inserted or updated
          values.

*Note `mysql_insert_id()': mysql-insert-id. returns `0' if the previous
statement does not use an `AUTO_INCREMENT' value. If you need to save
the value for later, be sure to call *Note `mysql_insert_id()':
mysql-insert-id. immediately after the statement that generates the
value.

The value of *Note `mysql_insert_id()': mysql-insert-id.  is affected
only by statements issued within the current client connection. It is
not affected by statements issued by other clients.

The `LAST_INSERT_ID()' SQL function will contain the value of the first
automatically generated value that was successfully inserted.
`LAST_INSERT_ID()' is not reset between statements because the value of
that function is maintained in the server. Another difference from
*Note `mysql_insert_id()': mysql-insert-id. is that `LAST_INSERT_ID()'
is not updated if you set an `AUTO_INCREMENT' column to a specific
non-special value. See *Note information-functions::.

*Note `mysql_insert_id()': mysql-insert-id. returns `0' following a
*Note `CALL': call. statement for a stored procedure that generates an
`AUTO_INCREMENT' value because in this case *Note `mysql_insert_id()':
mysql-insert-id. applies to *Note `CALL': call. and not the statement
within the procedure. Within the procedure, you can use
`LAST_INSERT_ID()' at the SQL level to obtain the `AUTO_INCREMENT'
value.

The reason for the differences between `LAST_INSERT_ID()' and *Note
`mysql_insert_id()': mysql-insert-id. is that `LAST_INSERT_ID()' is
made easy to use in scripts while *Note `mysql_insert_id()':
mysql-insert-id. tries to provide more exact information about what
happens to the `AUTO_INCREMENT' column.

*Return Values*

Described in the preceding discussion.

*Errors*

None.


File: manual.info,  Node: mysql-kill,  Next: mysql-library-end,  Prev: mysql-insert-id,  Up: c-api-functions

20.10.3.38 `mysql_kill()'
.........................

`int mysql_kill(MYSQL *mysql, unsigned long pid)'

*Description*

Asks the server to kill the thread specified by `pid'.

This function is deprecated. It is preferable to use *Note
`mysql_query()': mysql-query. to issue an SQL *Note `KILL': kill.
statement instead.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-library-end,  Next: mysql-library-init,  Prev: mysql-kill,  Up: c-api-functions

20.10.3.39 `mysql_library_end()'
................................

`void mysql_library_end(void)'

*Description*

This function finalizes the MySQL library. You should call it when you
are done using the library (for example, after disconnecting from the
server). The action taken by the call depends on whether your
application is linked to the MySQL client library or the MySQL embedded
server library. For a client program linked against the
`libmysqlclient' library by using the `-lmysqlclient' flag, *Note
`mysql_library_end()': mysql-library-end. performs some memory
management to clean up. For an embedded server application linked
against the `libmysqld' library by using the `-lmysqld' flag, *Note
`mysql_library_end()': mysql-library-end. shuts down the embedded
server and then cleans up.

For usage information, see *Note c-api-function-overview::, and *Note
mysql-library-init::.


File: manual.info,  Node: mysql-library-init,  Next: mysql-list-dbs,  Prev: mysql-library-end,  Up: c-api-functions

20.10.3.40 `mysql_library_init()'
.................................

`int mysql_library_init(int argc, char **argv, char **groups)'

*Description*

This function should be called to initialize the MySQL library before
you call any other MySQL function, whether your application is a
regular client program or uses the embedded server. If the application
uses the embedded server, this call starts the server and initializes
any subsystems (`mysys', `InnoDB', and so forth) that the server uses.

After your application is done using the MySQL library, call *Note
`mysql_library_end()': mysql-library-end. to clean up.  See *Note
mysql-library-end::.

The choice of whether the application operates as a regular client or
uses the embedded server depends on whether you use the
`libmysqlclient' or `libmysqld' library at link time to produce the
final executable. For additional information, see *Note
c-api-function-overview::.

In a non-multi-threaded environment, the call to *Note
`mysql_library_init()': mysql-library-init. may be omitted, because
*Note `mysql_init()': mysql-init.  will invoke it automatically as
necessary. However, *Note `mysql_library_init()': mysql-library-init.
is not thread-safe in a multi-threaded environment, and thus neither is
*Note `mysql_init()': mysql-init, which calls *Note
`mysql_library_init()': mysql-library-init. You must either call *Note
`mysql_library_init()': mysql-library-init.  prior to spawning any
threads, or else use a mutex to protect the call, whether you invoke
*Note `mysql_library_init()': mysql-library-init. or indirectly via
*Note `mysql_init()': mysql-init.  This should be done prior to any
other client library call.

The `argc' and `argv' arguments are analogous to the arguments to
`main()', and enable passing of options to the embedded server. For
convenience, `argc' may be `0' (zero) if there are no command-line
arguments for the server. This is the usual case for applications
intended for use only as regular (non-embedded) clients, and the call
typically is written as *Note `mysql_library_init(0, NULL, NULL)':
mysql-library-init.

     #include <mysql.h>
     #include <stdlib.h>

     int main(void) {
       if (mysql_library_init(0, NULL, NULL)) {
         fprintf(stderr, "could not initialize MySQL library\n");
         exit(1);
       }

       /* Use any MySQL API functions here */

       mysql_library_end();

       return EXIT_SUCCESS;
     }

When arguments are to be passed (`argc' is greater than `0'), the first
element of `argv' is ignored (it typically contains the program name).
*Note `mysql_library_init()': mysql-library-init. makes a copy of the
arguments so it is safe to destroy `argv' or `groups' after the call.

For embedded applications, if you want to connect to an external server
without starting the embedded server, you have to specify a negative
value for `argc'.

The `groups' argument should be an array of strings that indicate the
groups in option files from which options should be read. See *Note
option-files::. The final entry in the array should be `NULL'. For
convenience, if the `groups' argument itself is `NULL', the `[server]'
and `[embedded]' groups are used by default.

     #include <mysql.h>
     #include <stdlib.h>

     static char *server_args[] = {
       "this_program",       /* this string is not used */
       "--datadir=.",
       "--key_buffer_size=32M"
     };
     static char *server_groups[] = {
       "embedded",
       "server",
       "this_program_SERVER",
       (char *)NULL
     };

     int main(void) {
       if (mysql_library_init(sizeof(server_args) / sizeof(char *),
                             server_args, server_groups)) {
         fprintf(stderr, "could not initialize MySQL library\n");
         exit(1);
       }

       /* Use any MySQL API functions here */

       mysql_library_end();

       return EXIT_SUCCESS;
     }

*Return Values*

Zero if successful. Non-zero if an error occurred.


File: manual.info,  Node: mysql-list-dbs,  Next: mysql-list-fields,  Prev: mysql-library-init,  Up: c-api-functions

20.10.3.41 `mysql_list_dbs()'
.............................

`MYSQL_RES *mysql_list_dbs(MYSQL *mysql, const char *wild)'

*Description*

Returns a result set consisting of database names on the server that
match the simple regular expression specified by the `wild' parameter.
`wild' may contain the wildcard characters ``%'' or ``_'', or may be a
`NULL' pointer to match all databases. Calling *Note
`mysql_list_dbs()': mysql-list-dbs. is similar to executing the query
`SHOW DATABASES [LIKE WILD]'.

You must free the result set with *Note `mysql_free_result()':
mysql-free-result.

*Return Values*

A `MYSQL_RES' result set for success.  `NULL' if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-list-fields,  Next: mysql-list-processes,  Prev: mysql-list-dbs,  Up: c-api-functions

20.10.3.42 `mysql_list_fields()'
................................

`MYSQL_RES *mysql_list_fields(MYSQL *mysql, const char *table, const
char *wild)'

*Description*

Returns a result set consisting of field names in the given table that
match the simple regular expression specified by the `wild' parameter.
`wild' may contain the wildcard characters ``%'' or ``_'', or may be a
`NULL' pointer to match all fields. Calling *Note
`mysql_list_fields()': mysql-list-fields. is similar to executing the
query `SHOW COLUMNS FROM TBL_NAME [LIKE WILD]'.

It is recommended that you use `SHOW COLUMNS FROM TBL_NAME' instead of
*Note `mysql_list_fields()': mysql-list-fields.

You must free the result set with *Note `mysql_free_result()':
mysql-free-result.

*Return Values*

A `MYSQL_RES' result set for success.  `NULL' if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-list-processes,  Next: mysql-list-tables,  Prev: mysql-list-fields,  Up: c-api-functions

20.10.3.43 `mysql_list_processes()'
...................................

`MYSQL_RES *mysql_list_processes(MYSQL *mysql)'

*Description*

Returns a result set describing the current server threads. This is the
same kind of information as that reported by *Note `mysqladmin
processlist': mysqladmin. or a *Note `SHOW PROCESSLIST':
show-processlist. query.

You must free the result set with *Note `mysql_free_result()':
mysql-free-result.

*Return Values*

A `MYSQL_RES' result set for success.  `NULL' if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-list-tables,  Next: mysql-more-results,  Prev: mysql-list-processes,  Up: c-api-functions

20.10.3.44 `mysql_list_tables()'
................................

`MYSQL_RES *mysql_list_tables(MYSQL *mysql, const char *wild)'

*Description*

Returns a result set consisting of table names in the current database
that match the simple regular expression specified by the `wild'
parameter. `wild' may contain the wildcard characters ``%'' or ``_'',
or may be a `NULL' pointer to match all tables. Calling *Note
`mysql_list_tables()': mysql-list-tables. is similar to executing the
query `SHOW TABLES [LIKE WILD]'.

You must free the result set with *Note `mysql_free_result()':
mysql-free-result.

*Return Values*

A `MYSQL_RES' result set for success.  `NULL' if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-more-results,  Next: mysql-next-result,  Prev: mysql-list-tables,  Up: c-api-functions

20.10.3.45 `mysql_more_results()'
.................................

`my_bool mysql_more_results(MYSQL *mysql)'

*Description*

This function is used when you execute multiple statements specified as
a single statement string, or when you execute *Note `CALL': call.
statements, which can return multiple result sets.

*Note `mysql_more_results()': mysql-more-results. true if more results
exist from the currently executed statement, in which case the
application must call *Note `mysql_next_result()': mysql-next-result.
to fetch the results.

*Return Values*

`TRUE' (1) if more results exist.  `FALSE' (0) if no more results exist.

In most cases, you can call *Note `mysql_next_result()':
mysql-next-result. instead to test whether more results exist and
initiate retrieval if so.

See *Note c-api-multiple-queries::, and *Note mysql-next-result::.

*Errors*

None.


File: manual.info,  Node: mysql-next-result,  Next: mysql-num-fields,  Prev: mysql-more-results,  Up: c-api-functions

20.10.3.46 `mysql_next_result()'
................................

`int mysql_next_result(MYSQL *mysql)'

*Description*

This function is used when you execute multiple statements specified as
a single statement string, or when you use *Note `CALL': call.
statements to execute stored procedures, which can return multiple
result sets.

*Note `mysql_next_result()': mysql-next-result. reads the next
statement result and returns a status to indicate whether more results
exist. If *Note `mysql_next_result()': mysql-next-result. returns an
error, there are no more results.

Before each call to *Note `mysql_next_result()': mysql-next-result, you
must call *Note `mysql_free_result()': mysql-free-result. for the
current statement if it is a statement that returned a result set
(rather than just a result status).

After calling *Note `mysql_next_result()': mysql-next-result. the state
of the connection is as if you had called *Note `mysql_real_query()':
mysql-real-query. or *Note `mysql_query()': mysql-query. for the next
statement. This means that you can call *Note `mysql_store_result()':
mysql-store-result, *Note `mysql_warning_count()': mysql-warning-count,
*Note `mysql_affected_rows()': mysql-affected-rows, and so forth.

If your program uses *Note `CALL': call.  statements to execute stored
procedures, the `CLIENT_MULTI_RESULTS' flag must be enabled.  This is
because each *Note `CALL': call. returns a result to indicate the call
status, in addition to any result sets that might be returned by
statements executed within the procedure. Because *Note `CALL': call.
can return multiple results, you should process them using a loop that
calls *Note `mysql_next_result()': mysql-next-result.  to determine
whether there are more results.

`CLIENT_MULTI_RESULTS' can be enabled when you call *Note
`mysql_real_connect()': mysql-real-connect, either explicitly by
passing the `CLIENT_MULTI_RESULTS' flag itself, or implicitly by
passing `CLIENT_MULTI_STATEMENTS' (which also enables
`CLIENT_MULTI_RESULTS'). As of MySQL 6.0.8, `CLIENT_MULTI_RESULTS' is
enabled by default.

It is also possible to test whether there are more results by calling
*Note `mysql_more_results()': mysql-more-results.  However, this
function does not change the connection state, so if it returns true,
you must still call *Note `mysql_next_result()': mysql-next-result. to
advance to the next result.

For an example that shows how to use *Note `mysql_next_result()':
mysql-next-result, see *Note c-api-multiple-queries::.

*Return Values*

*Return Value*            *Description*
0                         Successful and there are more results
-1                        Successful and there are no more results
>0                        An error occurred

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order. For example if you
     didn't call *Note `mysql_use_result()': mysql-use-result. for a
     previous result set.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-num-fields,  Next: mysql-num-rows,  Prev: mysql-next-result,  Up: c-api-functions

20.10.3.47 `mysql_num_fields()'
...............................

`unsigned int mysql_num_fields(MYSQL_RES *result)'

To pass a `MYSQL*' argument instead, use `unsigned int
mysql_field_count(MYSQL *mysql)'.

*Description*

Returns the number of columns in a result set.

Note that you can get the number of columns either from a pointer to a
result set or to a connection handle. You would use the connection
handle if *Note `mysql_store_result()': mysql-store-result. or *Note
`mysql_use_result()': mysql-use-result. returned `NULL' (and thus you
have no result set pointer). In this case, you can call *Note
`mysql_field_count()': mysql-field-count. to determine whether *Note
`mysql_store_result()': mysql-store-result.  should have produced a
non-empty result. This allows the client program to take proper action
without knowing whether the query was a *Note `SELECT': select. (or
*Note `SELECT': select.-like) statement. The example shown here
illustrates how this may be done.

See *Note null-mysql-store-result::.

*Return Values*

An unsigned integer representing the number of columns in a result set.

*Errors*

None.

*Example*

     MYSQL_RES *result;
     unsigned int num_fields;
     unsigned int num_rows;

     if (mysql_query(&mysql,query_string))
     {
         // error
     }
     else // query succeeded, process any data returned by it
     {
         result = mysql_store_result(&mysql);
         if (result)  // there are rows
         {
             num_fields = mysql_num_fields(result);
             // retrieve rows, then call mysql_free_result(result)
         }
         else  // mysql_store_result() returned nothing; should it have?
         {
             if (mysql_errno(&mysql))
             {
                fprintf(stderr, "Error: %s\n", mysql_error(&mysql));
             }
             else if (mysql_field_count(&mysql) == 0)
             {
                 // query does not return data
                 // (it was not a SELECT)
                 num_rows = mysql_affected_rows(&mysql);
             }
         }
     }

An alternative (if you know that your query should have returned a
result set) is to replace the *Note `mysql_errno(&mysql)': mysql-errno.
call with a check whether *Note `mysql_field_count(&mysql)':
mysql-field-count.  returns 0. This happens only if something went
wrong.


File: manual.info,  Node: mysql-num-rows,  Next: mysql-options,  Prev: mysql-num-fields,  Up: c-api-functions

20.10.3.48 `mysql_num_rows()'
.............................

`my_ulonglong mysql_num_rows(MYSQL_RES *result)'

*Description*

Returns the number of rows in the result set.

The use of *Note `mysql_num_rows()': mysql-num-rows.  depends on
whether you use *Note `mysql_store_result()': mysql-store-result. or
*Note `mysql_use_result()': mysql-use-result. to return the result set.
If you use *Note `mysql_store_result()': mysql-store-result, *Note
`mysql_num_rows()': mysql-num-rows. may be called immediately. If you
use *Note `mysql_use_result()': mysql-use-result, *Note
`mysql_num_rows()': mysql-num-rows. does not return the correct value
until all the rows in the result set have been retrieved.

*Note `mysql_num_rows()': mysql-num-rows. is intended for use with
statements that return a result set, such as *Note `SELECT': select.
For statements such as *Note `INSERT': insert, *Note `UPDATE': update,
or *Note `DELETE': delete, the number of affected rows can be obtained
with *Note `mysql_affected_rows()': mysql-affected-rows.

*Return Values*

The number of rows in the result set.

*Errors*

None.


File: manual.info,  Node: mysql-options,  Next: mysql-ping,  Prev: mysql-num-rows,  Up: c-api-functions

20.10.3.49 `mysql_options()'
............................

`int mysql_options(MYSQL *mysql, enum mysql_option option, const void
*arg)'

*Description*

Can be used to set extra connect options and affect behavior for a
connection. This function may be called multiple times to set several
options.

*Note `mysql_options()': mysql-options. should be called after *Note
`mysql_init()': mysql-init. and before *Note `mysql_connect()':
mysql-connect. or *Note `mysql_real_connect()': mysql-real-connect.

The `option' argument is the option that you want to set; the `arg'
argument is the value for the option. If the option is an integer,
`arg' should point to the value of the integer.

The following list describes the possible options, their effect, and
how `arg' is used for each option. Several of the options apply only
when the application is linked against the `libmysqld' embedded server
library and are unused for applications linked against the `libmysql'
client library. For option descriptions that indicate `arg' is unused,
its value is irrelevant; it is conventional to pass 0.

   * `MYSQL_INIT_COMMAND' (argument type: `char *')

     SQL statement to execute when connecting to the MySQL server.
     Automatically re-executed if reconnection occurs.

   * `MYSQL_OPT_COMPRESS' (argument: not used)

     Use the compressed client/server protocol.

   * `MYSQL_OPT_CONNECT_TIMEOUT' (argument type: `unsigned int *')

     Connect timeout in seconds.

   * `MYSQL_OPT_GUESS_CONNECTION' (argument: not used)

     For an application linked against the `libmysqld' embedded server
     library, this allows the library to guess whether to use the
     embedded server or a remote server. `Guess' means that if the host
     name is set and is not `localhost', it uses a remote server. This
     behavior is the default.  `MYSQL_OPT_USE_EMBEDDED_CONNECTION' and
     `MYSQL_OPT_USE_REMOTE_CONNECTION' can be used to override it. This
     option is ignored for applications linked against the
     `libmysqlclient' client library.

   * `MYSQL_OPT_LOCAL_INFILE' (argument type: optional pointer to
     `unsigned int')

     If no pointer is given or if pointer points to an `unsigned int'
     that has a non-zero value, the `LOAD LOCAL INFILE' statement is
     enabled.

   * `MYSQL_OPT_NAMED_PIPE' (argument: not used)

     Use named pipes to connect to a MySQL server on Windows, if the
     server allows named-pipe connections.

   * `MYSQL_OPT_PROTOCOL' (argument type: `unsigned int *')

     Type of protocol to use. Should be one of the enum values of
     `mysql_protocol_type' defined in `mysql.h'.

   * `MYSQL_OPT_READ_TIMEOUT' (argument type: `unsigned int *')

     The timeout in seconds for attempts to read from the server.  Each
     attempt uses this timeout value and there are retries if
     necessary, so the total effective timeout value is three times the
     option value. You can set the value so that a lost connection can
     be detected earlier than the TCP/IP `Close_Wait_Timeout' value of
     10 minutes.  This option works only for TCP/IP connections.

   * `MYSQL_OPT_RECONNECT' (argument type: `my_bool *')

     Enable or disable automatic reconnection to the server if the
     connection is found to have been lost. Reconnect is off by
     default; this option provides a way to set reconnection behavior
     explicitly.

   * `MYSQL_SET_CLIENT_IP' (argument type: `char *')

     For an application linked against the `libmysqld' embedded server
     library (when `libmysqld' is compiled with authentication
     support), this means that the user is considered to have connected
     from the specified IP address (specified as a string) for
     authentication purposes. This option is ignored for applications
     linked against the `libmysqlclient' client library.

   * `MYSQL_OPT_SSL_VERIFY_SERVER_CERT' (argument type: `my_bool *')

     Enable or disable verification of the server's Common Name value
     in its certificate against the host name used when connecting to
     the server. The connection is rejected if there is a mismatch.
     This feature can be used to prevent man-in-the-middle attacks.
     Verification is disabled by default.

   * `MYSQL_OPT_USE_EMBEDDED_CONNECTION' (argument: not used)

     For an application linked against the `libmysqld' embedded server
     library, this forces the use of the embedded server for the
     connection.  This option is ignored for applications linked
     against the `libmysqlclient' client library.

   * `MYSQL_OPT_USE_REMOTE_CONNECTION' (argument: not used)

     For an application linked against the `libmysqld' embedded server
     library, this forces the use of a remote server for the
     connection. This option is ignored for applications linked against
     the `libmysqlclient' client library.

   * `MYSQL_OPT_USE_RESULT' (argument: not used)

     This option is unused.

   * `MYSQL_OPT_WRITE_TIMEOUT' (argument type: `unsigned int *')

     The timeout in seconds for attempts to write to the server.  Each
     attempt uses this timeout value and there are `net_retry_count'
     retries if necessary, so the total effective timeout value is
     `net_retry_count' times the option value. This option works only
     for TCP/IP connections.

   * `MYSQL_READ_DEFAULT_FILE' (argument type: `char *')

     Read options from the named option file instead of from `my.cnf'.

   * `MYSQL_READ_DEFAULT_GROUP' (argument type: `char *')

     Read options from the named group from `my.cnf' or the file
     specified with `MYSQL_READ_DEFAULT_FILE'.

   * `MYSQL_REPORT_DATA_TRUNCATION' (argument type: `my_bool *')

     Enable or disable reporting of data truncation errors for prepared
     statements via the `error' member of `MYSQL_BIND' structures.
     (Default: enabled.)

   * `MYSQL_SECURE_AUTH' (argument type: `my_bool *')

     Whether to connect to a server that does not support the password
     hashing used in MySQL 4.1.1 and later.

   * `MYSQL_SET_CHARSET_DIR' (argument type: `char *')

     The path name to the directory that contains character set
     definition files.

   * `MYSQL_SET_CHARSET_NAME' (argument type: `char *')

     The name of the character set to use as the default character set.

   * `MYSQL_SHARED_MEMORY_BASE_NAME' (argument type: `char *')

     The name of the shared-memory object for communication to the
     server on Windows, if the server supports shared-memory
     connections. Should have the same value as the
     `--shared-memory-base-name' option used for the *Note `mysqld':
     mysqld. server you want to connect to.

The `client' group is always read if you use `MYSQL_READ_DEFAULT_FILE'
or `MYSQL_READ_DEFAULT_GROUP'.

The specified group in the option file may contain the following
options.

*Option*                  *Description*
`character-sets-dir=PATH' The directory where character sets are
                          installed.
`compress'                Use the compressed client/server protocol.
`connect-timeout=SECONDS' Connect timeout in seconds. On Linux this
                          timeout is also used for waiting for the first
                          answer from the server.
`database=DB_NAME'        Connect to this database if no database was
                          specified in the connect command.
`debug'                   Debug options.
`default-character-set=CHARSET_NAME'The default character set to use.
`disable-local-infile'    Disable use of *Note `LOAD DATA LOCAL':
                          load-data.
`host=HOST_NAME'          Default host name.
`init-command=STMT'       Statement to execute when connecting to MySQL
                          server. Automatically re-executed if
                          reconnection occurs.
`interactive-timeout=SECONDS'Same as specifying `CLIENT_INTERACTIVE' to
                          *Note `mysql_real_connect()':
                          mysql-real-connect.  See *Note
                          mysql-real-connect::.
`local-infile[={0|1}]'    If no argument or non-zero argument, enable
                          use of *Note `LOAD DATA LOCAL': load-data.;
                          otherwise disable.
`max_allowed_packet=BYTES'Maximum size of packet that client can read
                          from server.
`multi-queries',          Allow multiple result sets from
`multi-results'           multiple-statement executions or stored
                          procedures.
`multi-statements'        Allow the client to send multiple statements
                          in a single string (separated by ``;'').
`password=PASSWORD'       Default password.
`pipe'                    Use named pipes to connect to a MySQL server
                          on Windows.
`port=PORT_NUM'           Default port number.
`protocol={TCP|SOCKET|PIPE|MEMORY}'The protocol to use when connecting to the
                          server.
`return-found-rows'       Tell *Note `mysql_info()': mysql-info. to
                          return found rows instead of updated rows when
                          using *Note `UPDATE': update.
`shared-memory-base-name=NAME'Shared-memory name to use to connect to server.
`socket=PATH'             Default socket file.
`ssl-ca=FILE_NAME'        Certificate Authority file.
`ssl-capath=PATH'         Certificate Authority directory.
`ssl-cert=FILE_NAME'      Certificate file.
`ssl-cipher=CIPHER_LIST'  Allowable SSL ciphers.
`ssl-key=FILE_NAME'       Key file.
`timeout=SECONDS'         Like `connect-timeout'.
`user'                    Default user.

`timeout' has been replaced by `connect-timeout', but `timeout' is
still supported in MySQL 6.0 for backward compatibility.

For more information about option files, see *Note option-files::.

Before MySQL 5.1.18, the `arg' argument was declared as `char *'.

*Return Values*

Zero for success. Non-zero if you specify an unknown option.

*Example*

The following *Note `mysql_options()': mysql-options.  calls request
the use of compression in the client/server protocol, cause options to
be read from the `[odbc]' group of option files, and disable
transaction autocommit mode:

     MYSQL mysql;

     mysql_init(&mysql);
     mysql_options(&mysql,MYSQL_OPT_COMPRESS,0);
     mysql_options(&mysql,MYSQL_READ_DEFAULT_GROUP,"odbc");
     mysql_options(&mysql,MYSQL_INIT_COMMAND,"SET autocommit=0");
     if (!mysql_real_connect(&mysql,"host","user","passwd","database",0,NULL,0))
     {
         fprintf(stderr, "Failed to connect to database: Error: %s\n",
               mysql_error(&mysql));
     }

This code requests that the client use the compressed client/server
protocol and read the additional options from the `odbc' section in the
`my.cnf' file.


File: manual.info,  Node: mysql-ping,  Next: mysql-query,  Prev: mysql-options,  Up: c-api-functions

20.10.3.50 `mysql_ping()'
.........................

`int mysql_ping(MYSQL *mysql)'

*Description*

Checks whether the connection to the server is working. If the
connection has gone down and auto-reconnect is enabled an attempt to
reconnect is made. If the connection is down and auto-reconnect is
disabled, *Note `mysql_ping()': mysql-ping. returns an error.

Auto-reconnect is disabled by default. To enable it, call *Note
`mysql_options()': mysql-options. with the `MYSQL_OPT_RECONNECT'
option. For details, see *Note mysql-options::.

*Note `mysql_ping()': mysql-ping. can be used by clients that remain
idle for a long while, to check whether the server has closed the
connection and reconnect if necessary.

If *Note `mysql_ping()': mysql-ping.) does cause a reconnect, there is
no explicit indication of it. To determine whether a reconnect occurs,
call *Note `mysql_thread_id()': mysql-thread-id. to get the original
connection identifier before calling *Note `mysql_ping()': mysql-ping,
and then call *Note `mysql_thread_id()': mysql-thread-id. again to see
whether the identifier has changed.

If reconnect occurs, some characteristics of the connection will have
been reset. For details about these characteristics, see *Note
auto-reconnect::.

*Return Values*

Zero if the connection to the server is alive. Non-zero if an error
occurred. A non-zero return does not indicate whether the MySQL server
itself is down; the connection might be broken for other reasons such
as network problems.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-query,  Next: mysql-real-connect,  Prev: mysql-ping,  Up: c-api-functions

20.10.3.51 `mysql_query()'
..........................

`int mysql_query(MYSQL *mysql, const char *stmt_str)'

*Description*

Executes the SQL statement pointed to by the null-terminated string
`stmt_str'. Normally, the string must consist of a single SQL statement
and you should not add a terminating semicolon (``;'') or `\g' to the
statement. If multiple-statement execution has been enabled, the string
can contain several statements separated by semicolons. See *Note
c-api-multiple-queries::.

*Note `mysql_query()': mysql-query. cannot be used for statements that
contain binary data; you must use *Note `mysql_real_query()':
mysql-real-query. instead.  (Binary data may contain the ``\0''
character, which *Note `mysql_query()': mysql-query. interprets as the
end of the statement string.)

If you want to know whether the statement should return a result set,
you can use *Note `mysql_field_count()': mysql-field-count. to check for
this. See *Note mysql-field-count::.

*Return Values*

Zero if the statement was successful. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-real-connect,  Next: mysql-real-escape-string,  Prev: mysql-query,  Up: c-api-functions

20.10.3.52 `mysql_real_connect()'
.................................

`MYSQL *mysql_real_connect(MYSQL *mysql, const char *host, const char
*user, const char *passwd, const char *db, unsigned int port, const
char *unix_socket, unsigned long client_flag)'

*Description*

*Note `mysql_real_connect()': mysql-real-connect. attempts to establish
a connection to a MySQL database engine running on `host'.  *Note
`mysql_real_connect()': mysql-real-connect. must complete successfully
before you can execute any other API functions that require a valid
`MYSQL' connection handle structure.

The parameters are specified as follows:

   * The first parameter should be the address of an existing `MYSQL'
     structure. Before calling *Note `mysql_real_connect()':
     mysql-real-connect. you must call *Note `mysql_init()':
     mysql-init. to initialize the `MYSQL' structure. You can change a
     lot of connect options with the *Note `mysql_options()':
     mysql-options. call. See *Note mysql-options::.

   * The value of `host' may be either a host name or an IP address. If
     `host' is `NULL' or the string `"localhost"', a connection to the
     local host is assumed: For Windows, the client connects using a
     shared-memory connection, if the server has shared-memory
     connections enabled. Otherwise, TCP/IP is used. For Unix, the
     client connects using a Unix socket file. For local connections,
     you can also influence the type of connection to use with the
     `MYSQL_OPT_PROTOCOL' or `MYSQL_OPT_NAMED_PIPE' options to *Note
     `mysql_options()': mysql-options. The type of connection must be
     supported by the server. For a `host' value of `"."' on Windows,
     the client connects using a named pipe, if the server has
     named-pipe connections enabled. If named-pipe connections are not
     enabled, an error occurs.

   * The `user' parameter contains the user's MySQL login ID. If `user'
     is `NULL' or the empty string `""', the current user is assumed.
     Under Unix, this is the current login name. Under Windows ODBC,
     the current user name must be specified explicitly. See the MyODBC
     section of *Note connectors-apis::.

   * The `passwd' parameter contains the password for `user'. If
     `passwd' is `NULL', only entries in the `user' table for the user
     that have a blank (empty) password field are checked for a match.
     This allows the database administrator to set up the MySQL
     privilege system in such a way that users get different privileges
     depending on whether they have specified a password.

     *Note*:

     Do not attempt to encrypt the password before calling *Note
     `mysql_real_connect()': mysql-real-connect.; password encryption
     is handled automatically by the client API.

   * The `user' and `passwd' parameters use whatever character set has
     been configured for the `MYSQL' object. By default, this is
     `latin1', but can be changed by calling *Note
     `mysql_options(mysql, MYSQL_SET_CHARSET_NAME, "CHARSET_NAME")':
     mysql-options. prior to connecting.

   * `db' is the database name. If `db' is not `NULL', the connection
     sets the default database to this value.

   * If `port' is not 0, the value is used as the port number for the
     TCP/IP connection. Note that the `host' parameter determines the
     type of the connection.

   * If `unix_socket' is not `NULL', the string specifies the socket or
     named pipe that should be used. Note that the `host' parameter
     determines the type of the connection.

   * The value of `client_flag' is usually 0, but can be set to a
     combination of the following flags to enable certain features.

     *Flag Name*             *Flag Description*
     `CLIENT_COMPRESS'       Use compression protocol.
     `CLIENT_FOUND_ROWS'     Return the number of found (matched) rows,
                             not the number of changed rows.
     `CLIENT_IGNORE_SIGPIPE' Prevents the client library from installing
                             a `SIGPIPE' signal handler. This can be
                             used to avoid conflicts with a handler that
                             the application has already installed.
     `CLIENT_IGNORE_SPACE'   Allow spaces after function names. Makes
                             all functions names reserved words.
     `CLIENT_INTERACTIVE'    Allow `interactive_timeout' seconds
                             (instead of `wait_timeout' seconds) of
                             inactivity before closing the connection.
                             The client's session `wait_timeout'
                             variable is set to the value of the session
                             `interactive_timeout' variable.
     `CLIENT_LOCAL_FILES'    Enable *Note `LOAD DATA LOCAL': load-data.
                             handling.
     `CLIENT_MULTI_RESULTS'  Tell the server that the client can handle
                             multiple result sets from
                             multiple-statement executions or stored
                             procedures.  This flag is automatically
                             enabled if `CLIENT_MULTI_STATEMENTS' is
                             enabled. See the note following this table
                             for more information about this flag.
     `CLIENT_MULTI_STATEMENTS'Tell the server that the client may send
                             multiple statements in a single string
                             (separated by ``;''). If this flag is not
                             set, multiple-statement execution is
                             disabled. See the note following this table
                             for more information about this flag.
     `CLIENT_NO_SCHEMA'      Don't allow the DB_NAME.TBL_NAME.COL_NAME
                             syntax. This is for ODBC. It causes the
                             parser to generate an error if you use that
                             syntax, which is useful for trapping bugs
                             in some ODBC programs.
     `CLIENT_ODBC'           Unused.
     `CLIENT_SSL'            Use SSL (encrypted protocol). This option
                             should not be set by application programs;
                             it is set internally in the client library.
                             Instead, use *Note `mysql_ssl_set()':
                             mysql-ssl-set.  before calling *Note
                             `mysql_real_connect()': mysql-real-connect.
     `CLIENT_REMEMBER_OPTIONS'Remember options specified by calls to
                             *Note `mysql_options()': mysql-options.
                             Without this option, if *Note
                             `mysql_real_connect()': mysql-real-connect.
                             fails, you must repeat the *Note
                             `mysql_options()': mysql-options.  calls
                             before trying to connect again. With this
                             option, the *Note `mysql_options()':
                             mysql-options.  calls need not be repeated.

If your program uses *Note `CALL': call.  statements to execute stored
procedures, the `CLIENT_MULTI_RESULTS' flag must be enabled.  This is
because each *Note `CALL': call. returns a result to indicate the call
status, in addition to any result sets that might be returned by
statements executed within the procedure. Because *Note `CALL': call.
can return multiple results, you should process them using a loop that
calls *Note `mysql_next_result()': mysql-next-result.  to determine
whether there are more results.

`CLIENT_MULTI_RESULTS' can be enabled when you call *Note
`mysql_real_connect()': mysql-real-connect, either explicitly by
passing the `CLIENT_MULTI_RESULTS' flag itself, or implicitly by
passing `CLIENT_MULTI_STATEMENTS' (which also enables
`CLIENT_MULTI_RESULTS'). As of MySQL 6.0.8, `CLIENT_MULTI_RESULTS' is
enabled by default.

If you enable `CLIENT_MULTI_STATEMENTS' or `CLIENT_MULTI_RESULTS', you
should process the result for every call to *Note `mysql_query()':
mysql-query. or *Note `mysql_real_query()': mysql-real-query. by using a
loop that calls *Note `mysql_next_result()': mysql-next-result. to
determine whether there are more results. For an example, see *Note
c-api-multiple-queries::.

For some parameters, it is possible to have the value taken from an
option file rather than from an explicit value in the *Note
`mysql_real_connect()': mysql-real-connect. call. To do this, call
*Note `mysql_options()': mysql-options. with the
`MYSQL_READ_DEFAULT_FILE' or `MYSQL_READ_DEFAULT_GROUP' option before
calling *Note `mysql_real_connect()': mysql-real-connect.  Then, in the
*Note `mysql_real_connect()': mysql-real-connect. call, specify the
`no-value' value for each parameter to be read from an option file:

   * For `host', specify a value of `NULL' or the empty string (`""').

   * For `user', specify a value of `NULL' or the empty string.

   * For `passwd', specify a value of `NULL'. (For the password, a
     value of the empty string in the *Note `mysql_real_connect()':
     mysql-real-connect. call cannot be overridden in an option file,
     because the empty string indicates explicitly that the MySQL
     account must have an empty password.)

   * For `db', specify a value of `NULL' or the empty string.

   * For `port', specify a value of 0.

   * For `unix_socket', specify a value of `NULL'.

If no value is found in an option file for a parameter, its default
value is used as indicated in the descriptions given earlier in this
section.

*Return Values*

A `MYSQL*' connection handle if the connection was successful, `NULL'
if the connection was unsuccessful. For a successful connection, the
return value is the same as the value of the first parameter.

*Errors*

   * `CR_CONN_HOST_ERROR'

     Failed to connect to the MySQL server.

   * `CR_CONNECTION_ERROR'

     Failed to connect to the local MySQL server.

   * `CR_IPSOCK_ERROR'

     Failed to create an IP socket.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SOCKET_CREATE_ERROR'

     Failed to create a Unix socket.

   * `CR_UNKNOWN_HOST'

     Failed to find the IP address for the host name.

   * `CR_VERSION_ERROR'

     A protocol mismatch resulted from attempting to connect to a
     server with a client library that uses a different protocol
     version.

   * `CR_NAMEDPIPEOPEN_ERROR'

     Failed to create a named pipe on Windows.

   * `CR_NAMEDPIPEWAIT_ERROR'

     Failed to wait for a named pipe on Windows.

   * `CR_NAMEDPIPESETSTATE_ERROR'

     Failed to get a pipe handler on Windows.

   * `CR_SERVER_LOST'

     If `connect_timeout' > 0 and it took longer than `connect_timeout'
     seconds to connect to the server or if the server died while
     executing the `init-command'.

   * `CR_ALREADY_CONNECTED'

     The `MYSQL' connection handle is already connected.

*Example*

     MYSQL mysql;

     mysql_init(&mysql);
     mysql_options(&mysql,MYSQL_READ_DEFAULT_GROUP,"your_prog_name");
     if (!mysql_real_connect(&mysql,"host","user","passwd","database",0,NULL,0))
     {
         fprintf(stderr, "Failed to connect to database: Error: %s\n",
               mysql_error(&mysql));
     }

By using *Note `mysql_options()': mysql-options. the MySQL library
reads the `[client]' and `[your_prog_name]' sections in the `my.cnf'
file which ensures that your program works, even if someone has set up
MySQL in some non-standard way.

Note that upon connection, *Note `mysql_real_connect()':
mysql-real-connect. sets the `reconnect' flag (part of the `MYSQL'
structure) to a value of `1' in versions of the API older than 5.0.3, or
`0' in newer versions. A value of `1' for this flag indicates that if a
statement cannot be performed because of a lost connection, to try
reconnecting to the server before giving up. You can use the
`MYSQL_OPT_RECONNECT' option to *Note `mysql_options()': mysql-options.
to control reconnection behavior.


File: manual.info,  Node: mysql-real-escape-string,  Next: mysql-real-query,  Prev: mysql-real-connect,  Up: c-api-functions

20.10.3.53 `mysql_real_escape_string()'
.......................................

`unsigned long mysql_real_escape_string(MYSQL *mysql, char *to, const
char *from, unsigned long length)'

Note that `mysql' must be a valid, open connection. This is needed
because the escaping depends on the character set in use by the server.

*Description*

This function is used to create a legal SQL string that you can use in
an SQL statement. See *Note string-syntax::.

The string in `from' is encoded to an escaped SQL string, taking into
account the current character set of the connection. The result is
placed in `to' and a terminating null byte is appended. Characters
encoded are `NUL' (ASCII 0), ``\n'', ``\r'', ``\'', ``''', ``"'', and
Control-Z (see *Note literals::). (Strictly speaking, MySQL requires
only that backslash and the quote character used to quote the string in
the query be escaped. This function quotes the other characters to make
them easier to read in log files.)

The string pointed to by `from' must be `length' bytes long. You must
allocate the `to' buffer to be at least `length*2+1' bytes long. (In
the worst case, each character may need to be encoded as using two
bytes, and you need room for the terminating null byte.) When *Note
`mysql_real_escape_string()': mysql-real-escape-string.  returns, the
contents of `to' is a null-terminated string. The return value is the
length of the encoded string, not including the terminating null
character.

If you need to change the character set of the connection, you should
use the *Note `mysql_set_character_set()': mysql-set-character-set.
function rather than executing a `SET NAMES' (or `SET CHARACTER SET')
statement.  *Note `mysql_set_character_set()': mysql-set-character-set.
works like `SET NAMES' but also affects the character set used by *Note
`mysql_real_escape_string()': mysql-real-escape-string, which `SET
NAMES' does not.

*Example*

     char query[1000],*end;

     end = strmov(query,"INSERT INTO test_table values(");
     *end++ = '\'';
     end += mysql_real_escape_string(&mysql, end,"What is this",12);
     *end++ = '\'';
     *end++ = ',';
     *end++ = '\'';
     end += mysql_real_escape_string(&mysql, end,"binary data: \0\r\n",16);
     *end++ = '\'';
     *end++ = ')';

     if (mysql_real_query(&mysql,query,(unsigned int) (end - query)))
     {
        fprintf(stderr, "Failed to insert row, Error: %s\n",
                mysql_error(&mysql));
     }

The `strmov()' function used in the example is included in the
`mysqlclient' library and works like `strcpy()' but returns a pointer
to the terminating null of the first parameter.

*Return Values*

The length of the value placed into `to', not including the terminating
null character.

*Errors*

None.


File: manual.info,  Node: mysql-real-query,  Next: mysql-refresh,  Prev: mysql-real-escape-string,  Up: c-api-functions

20.10.3.54 `mysql_real_query()'
...............................

`int mysql_real_query(MYSQL *mysql, const char *stmt_str, unsigned long
length)'

*Description*

Executes the SQL statement pointed to by `stmt_str', which should be a
string `length' bytes long. Normally, the string must consist of a
single SQL statement and you should not add a terminating semicolon
(``;'') or `\g' to the statement. If multiple-statement execution has
been enabled, the string can contain several statements separated by
semicolons. See *Note c-api-multiple-queries::.

*Note `mysql_query()': mysql-query. cannot be used for statements that
contain binary data; you must use *Note `mysql_real_query()':
mysql-real-query. instead.  (Binary data may contain the ``\0''
character, which *Note `mysql_query()': mysql-query. interprets as the
end of the statement string.) In addition, *Note `mysql_real_query()':
mysql-real-query. is faster than *Note `mysql_query()': mysql-query.
because it does not call `strlen()' on the statement string.

If you want to know whether the statement should return a result set,
you can use *Note `mysql_field_count()': mysql-field-count. to check for
this. See *Note mysql-field-count::.

*Return Values*

Zero if the statement was successful. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-refresh,  Next: mysql-reload,  Prev: mysql-real-query,  Up: c-api-functions

20.10.3.55 `mysql_refresh()'
............................

`int mysql_refresh(MYSQL *mysql, unsigned int options)'

*Description*

This function flushes tables or caches, or resets replication server
information. The connected user must have the `RELOAD' privilege.

The `options' argument is a bit mask composed from any combination of
the following values. Multiple values can be OR'ed together to perform
multiple operations with a single call.

   * `REFRESH_BACKUP_LOG'

     Flush the backup logs, like *Note `FLUSH BACKUP LOGS': flush. This
     option was added in MySQL 6.0.8.

   * `REFRESH_GRANT'

     Refresh the grant tables, like *Note `FLUSH PRIVILEGES': flush.

   * `REFRESH_LOG'

     Flush the logs, like *Note `FLUSH LOGS': flush.

   * `REFRESH_TABLES'

     Flush the table cache, like *Note `FLUSH TABLES': flush.

   * `REFRESH_HOSTS'

     Flush the host cache, like *Note `FLUSH HOSTS': flush.

   * `REFRESH_STATUS'

     Reset status variables, like `FLUSH STATUS'.

   * `REFRESH_THREADS'

     Flush the thread cache.

   * `REFRESH_SLAVE'

     On a slave replication server, reset the master server information
     and restart the slave, like *Note `RESET SLAVE': reset-slave.

   * `REFRESH_MASTER'

     On a master replication server, remove the binary log files listed
     in the binary log index and truncate the index file, like *Note
     `RESET MASTER': reset-master.

As of MySQL 6.0.8, *Note `mysql_refresh()': mysql-refresh. causes an
implicit commit to occur before and after executing.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-reload,  Next: mysql-rollback,  Prev: mysql-refresh,  Up: c-api-functions

20.10.3.56 `mysql_reload()'
...........................

`int mysql_reload(MYSQL *mysql)'

*Description*

Asks the MySQL server to reload the grant tables. The connected user
must have the `RELOAD' privilege.

This function is deprecated. It is preferable to use *Note
`mysql_query()': mysql-query. to issue an SQL *Note `FLUSH PRIVILEGES':
flush. statement instead.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-rollback,  Next: mysql-row-seek,  Prev: mysql-reload,  Up: c-api-functions

20.10.3.57 `mysql_rollback()'
.............................

`my_bool mysql_rollback(MYSQL *mysql)'

*Description*

Rolls back the current transaction.

The action of this function is subject to the value of the
`completion_type' system variable. In particular, if the value of
`completion_type' is 2, the server performs a release after terminating
a transaction and closes the client connection. The client program
should call *Note `mysql_close()': mysql-close. to close the connection
from the client side.

*Return Values*

Zero if successful. Non-zero if an error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-row-seek,  Next: mysql-row-tell,  Prev: mysql-rollback,  Up: c-api-functions

20.10.3.58 `mysql_row_seek()'
.............................

`MYSQL_ROW_OFFSET mysql_row_seek(MYSQL_RES *result, MYSQL_ROW_OFFSET
offset)'

*Description*

Sets the row cursor to an arbitrary row in a query result set.  The
`offset' value is a row offset that should be a value returned from
*Note `mysql_row_tell()': mysql-row-tell. or from *Note
`mysql_row_seek()': mysql-row-seek. This value is not a row number; if
you want to seek to a row within a result set by number, use *Note
`mysql_data_seek()': mysql-data-seek. instead.

This function requires that the result set structure contains the
entire result of the query, so *Note `mysql_row_seek()':
mysql-row-seek. may be used only in conjunction with *Note
`mysql_store_result()': mysql-store-result, not with *Note
`mysql_use_result()': mysql-use-result.

*Return Values*

The previous value of the row cursor. This value may be passed to a
subsequent call to *Note `mysql_row_seek()': mysql-row-seek.

*Errors*

None.


File: manual.info,  Node: mysql-row-tell,  Next: mysql-select-db,  Prev: mysql-row-seek,  Up: c-api-functions

20.10.3.59 `mysql_row_tell()'
.............................

`MYSQL_ROW_OFFSET mysql_row_tell(MYSQL_RES *result)'

*Description*

Returns the current position of the row cursor for the last *Note
`mysql_fetch_row()': mysql-fetch-row. This value can be used as an
argument to *Note `mysql_row_seek()': mysql-row-seek.

You should use *Note `mysql_row_tell()': mysql-row-tell.  only after
*Note `mysql_store_result()': mysql-store-result, not after *Note
`mysql_use_result()': mysql-use-result.

*Return Values*

The current offset of the row cursor.

*Errors*

None.


File: manual.info,  Node: mysql-select-db,  Next: mysql-set-character-set,  Prev: mysql-row-tell,  Up: c-api-functions

20.10.3.60 `mysql_select_db()'
..............................

`int mysql_select_db(MYSQL *mysql, const char *db)'

*Description*

Causes the database specified by `db' to become the default (current)
database on the connection specified by `mysql'. In subsequent queries,
this database is the default for table references that do not include an
explicit database specifier.

*Note `mysql_select_db()': mysql-select-db. fails unless the connected
user can be authenticated as having permission to use the database.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-set-character-set,  Next: mysql-set-local-infile-default,  Prev: mysql-select-db,  Up: c-api-functions

20.10.3.61 `mysql_set_character_set()'
......................................

`int mysql_set_character_set(MYSQL *mysql, const char *csname)'

*Description*

This function is used to set the default character set for the current
connection. The string `csname' specifies a valid character set name.
The connection collation becomes the default collation of the character
set. This function works like the `SET NAMES' statement, but also sets
the value of `mysql->charset', and thus affects the character set used
by *Note `mysql_real_escape_string()': mysql-real-escape-string.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Example*

     MYSQL mysql;

     mysql_init(&mysql);
     if (!mysql_real_connect(&mysql,"host","user","passwd","database",0,NULL,0))
     {
         fprintf(stderr, "Failed to connect to database: Error: %s\n",
               mysql_error(&mysql));
     }

     if (!mysql_set_character_set(&mysql, "utf8"))
     {
         printf("New client character set: %s\n",
                mysql_character_set_name(&mysql));
     }


File: manual.info,  Node: mysql-set-local-infile-default,  Next: mysql-set-local-infile-handler,  Prev: mysql-set-character-set,  Up: c-api-functions

20.10.3.62 `mysql_set_local_infile_default()'
.............................................

`void mysql_set_local_infile_default(MYSQL *mysql);'

*Description*

Sets the `LOAD LOCAL DATA INFILE' handler callback functions to the
defaults used internally by the C client library. The library calls
this function automatically if *Note
`mysql_set_local_infile_handler()': mysql-set-local-infile-handler.
has not been called or does not supply valid functions for each of its
callbacks.

The *Note `mysql_set_local_infile_default()':
mysql-set-local-infile-default.  function was added in MySQL 4.1.2.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-set-local-infile-handler,  Next: mysql-set-server-option,  Prev: mysql-set-local-infile-default,  Up: c-api-functions

20.10.3.63 `mysql_set_local_infile_handler()'
.............................................

`void mysql_set_local_infile_handler(MYSQL *mysql, int
(*local_infile_init)(void **, const char *, void *), int
(*local_infile_read)(void *, char *, unsigned int), void
(*local_infile_end)(void *), int (*local_infile_error)(void *, char*,
unsigned int), void *userdata);'

*Description*

This function installs callbacks to be used during the execution of
*Note `LOAD DATA LOCAL INFILE': load-data. statements. It enables
application programs to exert control over local (client-side) data
file reading. The arguments are the connection handler, a set of
pointers to callback functions, and a pointer to a data area that the
callbacks can use to share information.

To use *Note `mysql_set_local_infile_handler()':
mysql-set-local-infile-handler, you must write the following callback
functions:

     int
     local_infile_init(void **ptr, const char *filename, void *userdata);

The initialization function. This is called once to do any setup
necessary, open the data file, allocate data structures, and so forth.
The first `void**' argument is a pointer to a pointer. You can set the
pointer (that is, `*ptr') to a value that will be passed to each of the
other callbacks (as a `void*'). The callbacks can use this pointed-to
value to maintain state information. The `userdata' argument is the
same value that is passed to *Note `mysql_set_local_infile_handler()':
mysql-set-local-infile-handler.

The initialization function should return zero for success, non-zero
for an error.

     int
     local_infile_read(void *ptr, char *buf, unsigned int buf_len);

The data-reading function. This is called repeatedly to read the data
file. `buf' points to the buffer where the read data should be stored,
and `buf_len' is the maximum number of bytes that the callback can read
and store in the buffer. (It can read fewer bytes, but should not read
more.)

The return value is the number of bytes read, or zero when no more data
could be read (this indicates EOF). Return a value less than zero if an
error occurs.

     void
     local_infile_end(void *ptr)

The termination function. This is called once after
`local_infile_read()' has returned zero (EOF) or an error. This
function should deallocate any memory allocated by
`local_infile_init()' and perform any other cleanup necessary. It is
invoked even if the initalization function returns an error.

     int
     local_infile_error(void *ptr,
                        char *error_msg,
                        unsigned int error_msg_len);

The error-handling function. This is called to get a textual error
message to return to the user in case any of your other functions
returns an error. `error_msg' points to the buffer into which the
message should be written, and `error_msg_len' is the length of the
buffer.  The message should be written as a null-terminated string, so
the message can be at most `error_msg_len'-1 bytes long.

The return value is the error number.

Typically, the other callbacks store the error message in the data
structure pointed to by `ptr', so that `local_infile_error()' can copy
the message from there into `error_msg'.

After calling *Note `mysql_set_local_infile_handler()':
mysql-set-local-infile-handler.  in your C code and passing pointers to
your callback functions, you can then issue a *Note `LOAD DATA LOCAL
INFILE': load-data. statement (for example, by using *Note
`mysql_query()': mysql-query.). The client library automatically
invokes your callbacks. The file name specified in *Note `LOAD DATA
LOCAL INFILE': load-data. will be passed as the second parameter to the
`local_infile_init()' callback.

The *Note `mysql_set_local_infile_handler()':
mysql-set-local-infile-handler.  function was added in MySQL 4.1.2.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-set-server-option,  Next: mysql-shutdown,  Prev: mysql-set-local-infile-handler,  Up: c-api-functions

20.10.3.64 `mysql_set_server_option()'
......................................

`int mysql_set_server_option(MYSQL *mysql, enum enum_mysql_set_option
option)'

*Description*

Enables or disables an option for the connection.  `option' can have
one of the following values.

`MYSQL_OPTION_MULTI_STATEMENTS_ON'   Enable multiple-statement support
`MYSQL_OPTION_MULTI_STATEMENTS_OFF'  Disable multiple-statement support

If you enable multiple-statement support, you should retrieve results
from calls to *Note `mysql_query()': mysql-query. or *Note
`mysql_real_query()': mysql-real-query. by using a loop that calls
*Note `mysql_next_result()': mysql-next-result. to determine whether
there are more results. For an example, see *Note
c-api-multiple-queries::.

Enabling multiple-statement support with
`MYSQL_OPTION_MULTI_STATEMENTS_ON' does not have quite the same effect
as enabling it by passing the `CLIENT_MULTI_STATEMENTS' flag to *Note
`mysql_real_connect()': mysql-real-connect.: `CLIENT_MULTI_STATEMENTS'
also enables `CLIENT_MULTI_RESULTS'. If you are using the *Note `CALL':
call. SQL statement in your programs, multiple-result support must be
enabled; this means that `MYSQL_OPTION_MULTI_STATEMENTS_ON' by itself
is insufficient to allow the use of *Note `CALL': call.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `ER_UNKNOWN_COM_ERROR'

     The server didn't support *Note `mysql_set_server_option()':
     mysql-set-server-option.  (which is the case that the server is
     older than 4.1.1) or the server didn't support the option one
     tried to set.


File: manual.info,  Node: mysql-shutdown,  Next: mysql-sqlstate,  Prev: mysql-set-server-option,  Up: c-api-functions

20.10.3.65 `mysql_shutdown()'
.............................

`int mysql_shutdown(MYSQL *mysql, enum mysql_enum_shutdown_level
shutdown_level)'

*Description*

Asks the database server to shut down. The connected user must have the
`SHUTDOWN' privilege.  MySQL 6.0 servers support only one type of
shutdown; `shutdown_level' must be equal to `SHUTDOWN_DEFAULT'.
Additional shutdown levels are planned to make it possible to choose
the desired level.  Dynamically linked executables which have been
compiled with older versions of the `libmysqlclient' headers and call
*Note `mysql_shutdown()': mysql-shutdown. need to be used with the old
`libmysqlclient' dynamic library.

The shutdown process is described in *Note server-shutdown::.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-sqlstate,  Next: mysql-ssl-set,  Prev: mysql-shutdown,  Up: c-api-functions

20.10.3.66 `mysql_sqlstate()'
.............................

`const char *mysql_sqlstate(MYSQL *mysql)'

*Description*

Returns a null-terminated string containing the SQLSTATE error code for
the most recently executed SQL statement. The error code consists of
five characters. `'00000'' means `no error'. The values are specified
by ANSI SQL and ODBC. For a list of possible values, see *Note
error-handling::.

SQLSTATE values returned by *Note `mysql_sqlstate()': mysql-sqlstate.
differ from MySQL-specific error numbers returned by *Note
`mysql_errno()': mysql-errno. For example, the *Note `mysql': mysql.
client program displays errors using the following format, where `1146'
is the *Note `mysql_errno()': mysql-errno. value and `'42S02'' is the
corresponding *Note `mysql_sqlstate()': mysql-sqlstate. value:

     shell> SELECT * FROM no_such_table;
     ERROR 1146 (42S02): Table 'test.no_such_table' doesn't exist

Not all MySQL error numbers are mapped to SQLSTATE error codes.  The
value `'HY000'' (general error) is used for unmapped error numbers.

If you call *Note `mysql_sqlstate()': mysql-sqlstate.  after *Note
`mysql_real_connect()': mysql-real-connect.  fails, *Note
`mysql_sqlstate()': mysql-sqlstate. might not return a useful value.
For example, this happens if a host is blocked by the server and the
connection is closed without any SQLSTATE value being sent to the
client.

*Return Values*

A null-terminated character string containing the SQLSTATE error code.

*See Also*

See *Note mysql-errno::, *Note mysql-error::, and *Note
mysql-stmt-sqlstate::.


File: manual.info,  Node: mysql-ssl-set,  Next: mysql-stat,  Prev: mysql-sqlstate,  Up: c-api-functions

20.10.3.67 `mysql_ssl_set()'
............................

`my_bool mysql_ssl_set(MYSQL *mysql, const char *key, const char *cert,
const char *ca, const char *capath, const char *cipher)'

*Description*

*Note `mysql_ssl_set()': mysql-ssl-set. is used for establishing secure
connections using SSL. It must be called before *Note
`mysql_real_connect()': mysql-real-connect.

*Note `mysql_ssl_set()': mysql-ssl-set. does nothing unless SSL support
is enabled in the client library.

`mysql' is the connection handler returned from *Note `mysql_init()':
mysql-init. The other parameters are specified as follows:

   * `key' is the path name to the key file.

   * `cert' is the path name to the certificate file.

   * `ca' is the path name to the certificate authority file.

   * `capath' is the path name to a directory that contains trusted SSL
     CA certificates in pem format.

   * `cipher' is a list of allowable ciphers to use for SSL encryption.

Any unused SSL parameters may be given as `NULL'.

*Return Values*

This function always returns `0'. If SSL setup is incorrect, *Note
`mysql_real_connect()': mysql-real-connect. returns an error when you
attempt to connect.


File: manual.info,  Node: mysql-stat,  Next: mysql-store-result,  Prev: mysql-ssl-set,  Up: c-api-functions

20.10.3.68 `mysql_stat()'
.........................

`const char *mysql_stat(MYSQL *mysql)'

*Description*

Returns a character string containing information similar to that
provided by the *Note `mysqladmin status': mysqladmin.  command. This
includes uptime in seconds and the number of running threads,
questions, reloads, and open tables.

*Return Values*

A character string describing the server status.  `NULL' if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-store-result,  Next: mysql-thread-id,  Prev: mysql-stat,  Up: c-api-functions

20.10.3.69 `mysql_store_result()'
.................................

`MYSQL_RES *mysql_store_result(MYSQL *mysql)'

*Description*

After invoking *Note `mysql_query()': mysql-query. or *Note
`mysql_real_query()': mysql-real-query, you must call *Note
`mysql_store_result()': mysql-store-result. or *Note
`mysql_use_result()': mysql-use-result. for every statement that
successfully produces a result set (*Note `SELECT': select, *Note
`SHOW': show, *Note `DESCRIBE': describe, *Note `EXPLAIN': explain,
*Note `CHECK TABLE': check-table, and so forth). You must also call
*Note `mysql_free_result()': mysql-free-result. after you are done with
the result set.

You don't have to call *Note `mysql_store_result()':
mysql-store-result. or *Note `mysql_use_result()': mysql-use-result.
for other statements, but it does not do any harm or cause any notable
performance degradation if you call *Note `mysql_store_result()':
mysql-store-result. in all cases. You can detect whether the statement
has a result set by checking whether *Note `mysql_store_result()':
mysql-store-result. returns a non-zero value (more about this later on).

If you enable multiple-statement support, you should retrieve results
from calls to *Note `mysql_query()': mysql-query. or *Note
`mysql_real_query()': mysql-real-query. by using a loop that calls
*Note `mysql_next_result()': mysql-next-result. to determine whether
there are more results. For an example, see *Note
c-api-multiple-queries::.

If you want to know whether a statement should return a result set, you
can use *Note `mysql_field_count()': mysql-field-count. to check for
this. See *Note mysql-field-count::.

*Note `mysql_store_result()': mysql-store-result. reads the entire
result of a query to the client, allocates a `MYSQL_RES' structure, and
places the result into this structure.

*Note `mysql_store_result()': mysql-store-result. returns a null
pointer if the statement didn't return a result set (for example, if it
was an *Note `INSERT': insert.  statement).

*Note `mysql_store_result()': mysql-store-result. also returns a null
pointer if reading of the result set failed. You can check whether an
error occurred by checking whether *Note `mysql_error()': mysql-error.
returns a non-empty string, *Note `mysql_errno()': mysql-errno.
returns non-zero, or *Note `mysql_field_count()': mysql-field-count.
returns zero.

An empty result set is returned if there are no rows returned.  (An
empty result set differs from a null pointer as a return value.)

After you have called *Note `mysql_store_result()': mysql-store-result.
and gotten back a result that isn't a null pointer, you can call *Note
`mysql_num_rows()': mysql-num-rows. to find out how many rows are in
the result set.

You can call *Note `mysql_fetch_row()': mysql-fetch-row.  to fetch rows
from the result set, or *Note `mysql_row_seek()': mysql-row-seek. and
*Note `mysql_row_tell()': mysql-row-tell. to obtain or set the current
row position within the result set.

See *Note null-mysql-store-result::.

*Return Values*

A `MYSQL_RES' result structure with the results. `NULL' (0) if an error
occurred.

*Errors*

*Note `mysql_store_result()': mysql-store-result. resets *Note
`mysql_error()': mysql-error. and *Note `mysql_errno()': mysql-errno.
if it succeeds.

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-thread-id,  Next: mysql-use-result,  Prev: mysql-store-result,  Up: c-api-functions

20.10.3.70 `mysql_thread_id()'
..............................

`unsigned long mysql_thread_id(MYSQL *mysql)'

*Description*

Returns the thread ID of the current connection. This value can be used
as an argument to *Note `mysql_kill()': mysql-kill. to kill the thread.

If the connection is lost and you reconnect with *Note `mysql_ping()':
mysql-ping, the thread ID changes. This means you should not get the
thread ID and store it for later. You should get it when you need it.

*Return Values*

The thread ID of the current connection.

*Errors*

None.


File: manual.info,  Node: mysql-use-result,  Next: mysql-warning-count,  Prev: mysql-thread-id,  Up: c-api-functions

20.10.3.71 `mysql_use_result()'
...............................

`MYSQL_RES *mysql_use_result(MYSQL *mysql)'

*Description*

After invoking *Note `mysql_query()': mysql-query. or *Note
`mysql_real_query()': mysql-real-query, you must call *Note
`mysql_store_result()': mysql-store-result. or *Note
`mysql_use_result()': mysql-use-result. for every statement that
successfully produces a result set (*Note `SELECT': select, *Note
`SHOW': show, *Note `DESCRIBE': describe, *Note `EXPLAIN': explain,
*Note `CHECK TABLE': check-table, and so forth). You must also call
*Note `mysql_free_result()': mysql-free-result. after you are done with
the result set.

*Note `mysql_use_result()': mysql-use-result. initiates a result set
retrieval but does not actually read the result set into the client like
*Note `mysql_store_result()': mysql-store-result. does.  Instead, each
row must be retrieved individually by making calls to *Note
`mysql_fetch_row()': mysql-fetch-row. This reads the result of a query
directly from the server without storing it in a temporary table or
local buffer, which is somewhat faster and uses much less memory than
*Note `mysql_store_result()': mysql-store-result. The client allocates
memory only for the current row and a communication buffer that may
grow up to `max_allowed_packet' bytes.

On the other hand, you shouldn't use *Note `mysql_use_result()':
mysql-use-result. if you are doing a lot of processing for each row on
the client side, or if the output is sent to a screen on which the user
may type a `^S' (stop scroll). This ties up the server and prevent
other threads from updating any tables from which the data is being
fetched.

When using *Note `mysql_use_result()': mysql-use-result, you must
execute *Note `mysql_fetch_row()': mysql-fetch-row. until a `NULL'
value is returned, otherwise, the unfetched rows are returned as part
of the result set for your next query. The C API gives the error
`Commands out of sync; you can't run this command now' if you forget to
do this!

You may not use *Note `mysql_data_seek()': mysql-data-seek, *Note
`mysql_row_seek()': mysql-row-seek, *Note `mysql_row_tell()':
mysql-row-tell, *Note `mysql_num_rows()': mysql-num-rows, or *Note
`mysql_affected_rows()': mysql-affected-rows. with a result returned
from *Note `mysql_use_result()': mysql-use-result, nor may you issue
other queries until *Note `mysql_use_result()': mysql-use-result. has
finished.  (However, after you have fetched all the rows, *Note
`mysql_num_rows()': mysql-num-rows. accurately returns the number of
rows fetched.)

You must call *Note `mysql_free_result()': mysql-free-result. once you
are done with the result set.

When using the `libmysqld' embedded server, the memory benefits are
essentially lost because memory usage incrementally increases with each
row retrieved until *Note `mysql_free_result()': mysql-free-result. is
called.

*Return Values*

A `MYSQL_RES' result structure.  `NULL' if an error occurred.

*Errors*

*Note `mysql_use_result()': mysql-use-result. resets *Note
`mysql_error()': mysql-error. and *Note `mysql_errno()': mysql-errno.
if it succeeds.

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-warning-count,  Prev: mysql-use-result,  Up: c-api-functions

20.10.3.72 `mysql_warning_count()'
..................................

`unsigned int mysql_warning_count(MYSQL *mysql)'

*Description*

Returns the number of warnings generated during execution of the
previous SQL statement.

*Return Values*

The warning count.

*Errors*

None.


File: manual.info,  Node: c-api-prepared-statements,  Next: c-api-prepared-statement-datatypes,  Prev: c-api-functions,  Up: c

20.10.4 C API Prepared Statements
---------------------------------

The MySQL client/server protocol provides for the use of prepared
statements. This capability uses the `MYSQL_STMT' statement handler
data structure returned by the *Note `mysql_stmt_init()':
mysql-stmt-init. initialization function. Prepared execution is an
efficient way to execute a statement more than once. The statement is
first parsed to prepare it for execution. Then it is executed one or
more times at a later time, using the statement handle returned by the
initialization function.

Prepared execution is faster than direct execution for statements
executed more than once, primarily because the query is parsed only
once. In the case of direct execution, the query is parsed every time
it is executed. Prepared execution also can provide a reduction of
network traffic because for each execution of the prepared statement,
it is necessary only to send the data for the parameters.

Prepared statements might not provide a performance increase in some
situations. For best results, test your application both with prepared
and non-prepared statements and choose whichever yields best
performance.

Another advantage of prepared statements is that it uses a binary
protocol that makes data transfer between client and server more
efficient.

The following statements can be used as prepared statements:

     CALL
     CREATE TABLE
     DELETE
     DO
     INSERT
     REPLACE
     SELECT
     SET
     UPDATE
     ANALYZE TABLE
     OPTIMIZE TABLE
     REPAIR TABLE
     CACHE INDEX
     CHANGE MASTER
     CHECKSUM {TABLE | TABLES}
     {CREATE | RENAME | DROP} DATABASE
     {CREATE | RENAME | DROP} USER
     FLUSH {TABLE | TABLES | TABLES WITH READ LOCK | HOSTS | PRIVILEGES
       | LOGS | STATUS | MASTER | SLAVE | DES_KEY_FILE | USER_RESOURCES}
     GRANT
     REVOKE
     KILL
     LOAD INDEX INTO CACHE
     RESET {MASTER | SLAVE | QUERY CACHE}
     SHOW BINLOG EVENTS
     SHOW CREATE {PROCEDURE | FUNCTION | EVENT | TABLE | VIEW}
     SHOW {AUTHORS | CONTRIBUTORS | WARNINGS | ERRORS}
     SHOW {MASTER | BINARY} LOGS
     SHOW {MASTER | SLAVE} STATUS
     SLAVE {START | STOP}
     INSTALL PLUGIN
     UNINSTALL PLUGIN

Other statements are not yet supported in MySQL 6.0.

As of MySQL 6.0.6, metadata changes to tables or views referred to by
prepared statements are detected and cause automatic repreparation of
the statement when it is next executed. For more information, see *Note
statement-repreparation::.


File: manual.info,  Node: c-api-prepared-statement-datatypes,  Next: c-api-prepared-statement-function-overview,  Prev: c-api-prepared-statements,  Up: c

20.10.5 C API Prepared Statement Data types
-------------------------------------------

Prepared statements use several data structures:

   * To prepare a statement, pass the statement string to *Note
     `mysql_stmt_init()': mysql-stmt-init, which returns a pointer to a
     `MYSQL_STMT' data structure.

   * To provide input parameters for a prepared statement, set up
     `MYSQL_BIND' structures and pass them to *Note
     `mysql_stmt_bind_param()': mysql-stmt-bind-param. To receive
     output column values, set up `MYSQL_BIND' structures and pass them
     to *Note `mysql_stmt_bind_result()': mysql-stmt-bind-result.

   * The `MYSQL_TIME' structure is used to transfer temporal data in
     both directions.

The following discussion describes the prepared statement data types in
detail.

   * `MYSQL_STMT'

     This structure represents a prepared statement. A statement is
     created by calling *Note `mysql_stmt_init()': mysql-stmt-init,
     which returns a statement handle (that is, a pointer to a
     `MYSQL_STMT'). The handle is used for all subsequent operations
     with the statement until you close it with *Note
     `mysql_stmt_close()': mysql-stmt-close, at which point the handle
     becomes invalid.

     The `MYSQL_STMT' structure has no members that are intended for
     application use. Also, you should not try to make a copy of a
     `MYSQL_STMT' structure. There is no guarantee that such a copy
     will be usable.

     Multiple statement handles can be associated with a single
     connection. The limit on the number of handles depends on the
     available system resources.

   * `MYSQL_BIND'

     This structure is used both for statement input (data values sent
     to the server) and output (result values returned from the server):

        * For input, `MYSQL_BIND' is used with *Note
          `mysql_stmt_bind_param()': mysql-stmt-bind-param. to bind
          parameter data values to buffers for use by *Note
          `mysql_stmt_execute()': mysql-stmt-execute.

        * For output, `MYSQL_BIND' is used with *Note
          `mysql_stmt_bind_result()': mysql-stmt-bind-result.  to bind
          result set buffers for use in fetching rows with *Note
          `mysql_stmt_fetch()': mysql-stmt-fetch.

     To use a `MYSQL_BIND' structure, you should zero its contents to
     initialize it, and then set its members appropriately. For
     example, to declare and initialize an array of three `MYSQL_BIND'
     structures, use this code:

          MYSQL_BIND bind[3];
          memset(bind, 0, sizeof(bind));

     The `MYSQL_BIND' structure contains the following members for use
     by application programs. For several of the members, the manner of
     use depends on whether the structure is used for input or output.

        * `enum enum_field_types buffer_type'

          The type of the buffer. This member indicates the data type
          of the C language variable that you are binding to the
          statement parameter. The allowable `buffer_type' values are
          listed later in this section. For input, `buffer_type'
          indicates the type of the variable containing the value that
          you will send to the server. For output, it indicates the
          type of the variable into which you want a value received
          from the server to be stored.

        * `void *buffer'

          A pointer to the buffer to be used for data transfer. This is
          the address of a variable.

          For input, `buffer' is a pointer to the variable in which a
          statement parameter's data value is stored. When you call
          *Note `mysql_stmt_execute()': mysql-stmt-execute, MySQL takes
          the value that you have stored in the variable and uses it in
          place of the corresponding parameter marker in the statement.

          For output, `buffer' is a pointer to the variable in which to
          return a result set column value.  When you call *Note
          `mysql_stmt_fetch()': mysql-stmt-fetch, MySQL returns a
          column value and stores it in this variable. You can access
          the value when the call returns.

          To minimize the need for MySQL to perform type conversions
          between C language values on the client side and SQL values
          on the server side, use variables that have types similar to
          those of the corresponding SQL values. For numeric data
          types, `buffer' should point to a variable of the proper
          numeric C type. (For `char' or integer variables, you should
          also indicate whether the variable has the `unsigned'
          attribute by setting the `is_unsigned' member, described
          later in this list.) For character (non-binary) and binary
          string data types, `buffer' should point to a character
          buffer. For date and time data types, `buffer' should point
          to a `MYSQL_TIME' structure.

          See the notes about type conversions later in the section.

        * `unsigned long buffer_length'

          The actual size of `*buffer' in bytes.  This indicates the
          maximum amount of data that can be stored in the buffer. For
          character and binary C data, the `buffer_length' value
          specifies the length of `*buffer' when used with *Note
          `mysql_stmt_bind_param()': mysql-stmt-bind-param. to specify
          input values, or the maximum number of output data bytes that
          can be fetched into the buffer when used with *Note
          `mysql_stmt_bind_result()': mysql-stmt-bind-result.

        * `unsigned long *length'

          A pointer to an `unsigned long' variable that indicates the
          actual number of bytes of data stored in `*buffer'. `length'
          is used for character or binary C data.

          For input parameter data binding, `length' points to an
          `unsigned long' variable that indicates the actual length of
          the parameter value stored in `*buffer'; this is used by
          *Note `mysql_stmt_execute()': mysql-stmt-execute.

          For output value binding, the return value of *Note
          `mysql_stmt_fetch()': mysql-stmt-fetch.  determines the
          interpretation of the length:

             * If *Note `mysql_stmt_fetch()': mysql-stmt-fetch.
               returns 0, `*length' indicates the actual length of the
               parameter value.

             * If *Note `mysql_stmt_fetch()': mysql-stmt-fetch.
               returns `MYSQL_DATA_TRUNCATED', `*length' indicates the
               non-truncated length of the parameter value. In this
               case, the minimum of `*length' and `buffer_length'
               indicates the actual length of the value.

          `length' is ignored for numeric and temporal data types
          because the length of the data value is determined by the
          `buffer_type' value.

          If you need to be able to determine the length of a returned
          value before fetching it with *Note `mysql_stmt_fetch()':
          mysql-stmt-fetch, see *Note mysql-stmt-fetch::, for some
          strategies.

        * `my_bool *is_null'

          This member points to a `my_bool' variable that is true if a
          value is `NULL', false if it is not `NULL'. For input, set
          `*is_null' to true to indicate that you are passing a `NULL'
          value as a statement parameter.

          The reason that `is_null' is not a boolean scalar but is
          instead a _pointer_ to a boolean scalar is to provide
          flexibility in how you specify `NULL' values:

             * If your data values are always `NULL', use
               `MYSQL_TYPE_NULL' as the `buffer_type' value when you
               bind the column. The other members do not matter.

             * If your data values are always `NOT NULL', set the other
               members appropriately for the variable you are binding,
               and set `is_null = (my_bool*) 0'.

             * In all other cases, set the other members
               appriopriately, and set `is_null' to the address of a
               `my_bool' variable.  Set that variable's value to true
               or false appropriately between executions to indicate
               whether data values are `NULL' or `NOT NULL',
               respectively.

          For output, the value pointed to by `is_null' is set to true
          after you fetch a row if the result set column value returned
          from the statement is `NULL'.

        * `my_bool is_unsigned'

          This member is used for C variables with data types that can
          be `unsigned' (`char', `short int', `int', `long long int').
          Set `is_unsigned' to true if the variable pointed to by
          `buffer' is `unsigned' and false otherwise. For example, if
          you bind a `signed char' variable to `buffer', specify a type
          code of `MYSQL_TYPE_TINY' and set `is_unsigned' to false. If
          you bind an `unsigned char' instead, the type code is the
          same but `is_unsigned' should be true. (For `char', it is not
          defined whether it is signed or unsigned, so it is best to be
          explicit about signedness by using `signed char' or `unsigned
          char'.)

          `is_unsigned' applies only to the C language variable on the
          client side. It indicates nothing about the signedness of the
          corresponding SQL value on the server side. For example, if
          you use an `int' variable to supply a value for a `BIGINT
          UNSIGNED' column, `is_unsigned' should be false because `int'
          is a signed type. If you use an `unsigned int' variable to
          supply a value for a *Note `BIGINT': numeric-types. column,
          `is_unsigned' should be true because `unsigned int' is an
          unsigned type. MySQL performs the proper conversion between
          signed and unsigned values in both directions, although a
          warning occurs if truncation results.

        * `my_bool *error'

          For output, set this member to point to a `my_bool' variable
          to have truncation information for the parameter stored there
          after a row fetching operation. (Truncation reporting is
          enabled by default, but can be controlled by calling *Note
          `mysql_options()': mysql-options. with the
          `MYSQL_REPORT_DATA_TRUNCATION' option.)  When truncation
          reporting is enabled, *Note `mysql_stmt_fetch()':
          mysql-stmt-fetch. returns `MYSQL_DATA_TRUNCATED' and `*error'
          is true in the `MYSQL_BIND' structures for parameters in
          which truncation occurred. Truncation indicates loss of sign
          or significant digits, or that a string was too long to fit
          in a column.

   * `MYSQL_TIME'

     This structure is used to send and receive *Note `DATE': datetime,
     *Note `TIME': time, *Note `DATETIME': datetime, and *Note
     `TIMESTAMP': datetime. data directly to and from the server. Set
     the `buffer_type' member of a `MYSQL_BIND' structure to one of the
     temporal types (`MYSQL_TYPE_TIME', `MYSQL_TYPE_DATE',
     `MYSQL_TYPE_DATETIME', `MYSQL_TYPE_TIMESTAMP'), and set the
     `buffer' member to point to a `MYSQL_TIME' structure.

     The `MYSQL_TIME' structure contains the members listed in the
     following table.

     *Member*                    *Description*
     `unsigned int year'         The year
     `unsigned int month'        The month of the year
     `unsigned int day'          The day of the month
     `unsigned int hour'         The hour of the day
     `unsigned int minute'       The minute of the hour
     `unsigned int second'       The second of the minute
     `my_bool neg'               A boolean flag to indicate whether the
                                 time is negative
     `unsigned long second_part' The fractional part of the second in
                                 microseconds; currently unused

     Only those parts of a `MYSQL_TIME' structure that apply to a given
     type of temporal value are used. The `year', `month', and `day'
     elements are used for *Note `DATE': datetime, *Note `DATETIME':
     datetime, and *Note `TIMESTAMP': datetime. values. The `hour',
     `minute', and `second' elements are used for *Note `TIME': time,
     *Note `DATETIME': datetime, and *Note `TIMESTAMP': datetime.
     values. See *Note c-api-prepared-statement-date-handling::.

The following table shows the allowable values that may be specified in
the `buffer_type' member of `MYSQL_BIND' structures for input values.
The value should be chosen according to the data type of the C language
variable that you are binding. If the variable is `unsigned', you
should also set the `is_unsigned' member to true. The table shows the C
variable types that you can use, the corresponding type codes, and the
SQL data types for which the supplied value can be used without
conversion.

*Input Variable C      `buffer_type' *Value*     *SQL Type of Destination
Type*                                            Value*
`signed char'          `MYSQL_TYPE_TINY'         *Note `TINYINT':
                                                 numeric-types.
`short int'            `MYSQL_TYPE_SHORT'        *Note `SMALLINT':
                                                 numeric-types.
`int'                  `MYSQL_TYPE_LONG'         *Note `INT':
                                                 numeric-types.
`long long int'        `MYSQL_TYPE_LONGLONG'     *Note `BIGINT':
                                                 numeric-types.
`float'                `MYSQL_TYPE_FLOAT'        *Note `FLOAT':
                                                 numeric-types.
`double'               `MYSQL_TYPE_DOUBLE'       *Note `DOUBLE':
                                                 numeric-types.
`MYSQL_TIME'           `MYSQL_TYPE_TIME'         *Note `TIME': time.
`MYSQL_TIME'           `MYSQL_TYPE_DATE'         *Note `DATE': datetime.
`MYSQL_TIME'           `MYSQL_TYPE_DATETIME'     *Note `DATETIME':
                                                 datetime.
`MYSQL_TIME'           `MYSQL_TYPE_TIMESTAMP'    *Note `TIMESTAMP':
                                                 datetime.
`char[]'               `MYSQL_TYPE_STRING' (for  `TEXT, CHAR, VARCHAR'
                       non-binary data)          
`char[]'               `MYSQL_TYPE_BLOB' (for    `BLOB, BINARY, VARBINARY'
                       binary data)              
                       `MYSQL_TYPE_NULL'         `NULL'

The use of `MYSQL_TYPE_NULL' is described earlier in connection with
the `is_null' member.

The following table shows the allowable values that may be specified in
the `buffer_type' member of `MYSQL_BIND' structures for output values.
The value should be chosen according to the data type of the C language
variable that you are binding. If the variable is `unsigned', you
should also set the `is_unsigned' member to true. The table shows the
SQL types of received values, the corresponding type code that such
values have in result set metadata, and the recommended C language data
types to bind to the `MYSQL_BIND' structure to receive the SQL values
without conversion.

If there is a mismatch between the C variable type on the client side
and the corresponding SQL value on the server side, MySQL performs
implicit type conversions in both directions.

*SQL Type of Received  `buffer_type' *Value*     *Output Variable C Type*
Value*                                           
*Note `TINYINT':       `MYSQL_TYPE_TINY'         `signed char'
numeric-types.                                   
*Note `SMALLINT':      `MYSQL_TYPE_SHORT'        `short int'
numeric-types.                                   
*Note `MEDIUMINT':     `MYSQL_TYPE_INT24'        `int'
numeric-types.                                   
*Note `INT':           `MYSQL_TYPE_LONG'         `int'
numeric-types.                                   
*Note `BIGINT':        `MYSQL_TYPE_LONGLONG'     `long long int'
numeric-types.                                   
*Note `FLOAT':         `MYSQL_TYPE_FLOAT'        `float'
numeric-types.                                   
*Note `DOUBLE':        `MYSQL_TYPE_DOUBLE'       `double'
numeric-types.                                   
*Note `DECIMAL':       `MYSQL_TYPE_NEWDECIMAL'   `char[]'
numeric-types.                                   
*Note `YEAR': year.    `MYSQL_TYPE_SHORT'        `short int'
*Note `TIME': time.    `MYSQL_TYPE_TIME'         `MYSQL_TIME'
*Note `DATE':          `MYSQL_TYPE_DATE'         `MYSQL_TIME'
datetime.                                        
*Note `DATETIME':      `MYSQL_TYPE_DATETIME'     `MYSQL_TIME'
datetime.                                        
*Note `TIMESTAMP':     `MYSQL_TYPE_TIMESTAMP'    `MYSQL_TIME'
datetime.                                        
`CHAR, BINARY'         `MYSQL_TYPE_STRING'       `char[]'
`VARCHAR, VARBINARY'   `MYSQL_TYPE_VAR_STRING'   `char[]'
`TINYBLOB, TINYTEXT'   `MYSQL_TYPE_TINY_BLOB'    `char[]'
`BLOB, TEXT'           `MYSQL_TYPE_BLOB'         `char[]'
`MEDIUMBLOB,           `MYSQL_TYPE_MEDIUM_BLOB'  `char[]'
MEDIUMTEXT'                                      
`LONGBLOB, LONGTEXT'   `MYSQL_TYPE_LONG_BLOB'    `char[]'
*Note `BIT':           `MYSQL_TYPE_BIT'          `char[]'
numeric-types.                                   

MySQL knows the type code for the SQL value on the server side.  The
`buffer_type' value indicates the MySQL the type code of the C variable
that holds the value on the client side. The two codes together tell
MySQL what conversion must be performed, if any. Here are some examples:

   * If you use `MYSQL_TYPE_LONG' with an `int' variable to pass an
     integer value to the server that is to be stored into a *Note
     `FLOAT': numeric-types. column, MySQL converts the value to
     floating-point format before storing it.

   * If you fetch an SQL *Note `MEDIUMINT': numeric-types.  column
     value, but specify a `buffer_type' value of `MYSQL_TYPE_LONGLONG'
     and use a C variable of type `long long int' as the destination
     buffer, MySQL will convert the *Note `MEDIUMINT': numeric-types.
     value (which requires less than 8 bytes) for storage into the
     `long long int' (an 8-byte variable).

   * If you fetch a numeric column with a value of 255 into a `char[4]'
     character array and specify a `buffer_type' value of
     `MYSQL_TYPE_STRING', the resulting value in the array will be a
     4-byte string containing `'255\0''.

   * *Note `DECIMAL': numeric-types. values are returned as strings,
     which is why the corresponding C type is `char[]'.  *Note
     `DECIMAL': numeric-types. values returned by the server correspond
     to the string representation of the original server-side value.
     For example, `12.345' is returned to the client as `'12.345''. If
     you specify `MYSQL_TYPE_NEWDECIMAL' and bind a string buffer to
     the `MYSQL_BIND' structure, *Note `mysql_stmt_fetch()':
     mysql-stmt-fetch. stores the value in the buffer without
     conversion. If instead you specify a numeric variable and type
     code, *Note `mysql_stmt_fetch()': mysql-stmt-fetch. converts the
     string-format *Note `DECIMAL': numeric-types. value to numeric
     form.

   * For the `MYSQL_TYPE_BIT' type code, *Note `BIT': numeric-types.
     values are returned into a string buffer (thus, the corresponding
     C type is `char[]' here, too). The value represents a bit string
     that requires interpretation on the client side. To return the
     value as a type that is easier to deal with, you can cause the
     value to be cast to integer using either of the following types of
     expressions:

          SELECT bit_col + 0 FROM t
          SELECT CAST(bit_col AS UNSIGNED) FROM t

     To retrieve the value, bind an integer variable large enough to
     hold the value and specify the appropriate corresponding integer
     type code.

Before binding variables to the `MYSQL_BIND' structures that are to be
used for fetching column values, you can check the type codes for each
column of the result set. This might be desirable if you want to
determine which variable types would be best to use to avoid type
conversions. To get the type codes, call *Note
`mysql_stmt_result_metadata()': mysql-stmt-result-metadata.  after
executing the prepared statement with *Note `mysql_stmt_execute()':
mysql-stmt-execute. The metadata provides access to the type codes for
the result set as described in *Note mysql-stmt-result-metadata::, and
*Note c-api-datatypes::.

If you cause the `max_length' member of the `MYSQL_FIELD' column
metadata structures to be set (by calling *Note
`mysql_stmt_attr_set()': mysql-stmt-attr-set.), be aware that the
`max_length' values for the result set indicate the lengths of the
longest string representation of the result values, not the lengths of
the binary representation. That is, `max_length' does not necessarily
correspond to the size of the buffers needed to fetch the values with
the binary protocol used for prepared statements. The size of the
buffers should be chosen according to the types of the variables into
which you fetch the values.

For input character (non-binary) string data (indicated by
`MYSQL_TYPE_STRING'), the value is assumed to be in the character set
indicated by the `character_set_client' system variable. If the value
is stored into a column with a different character set, the appropriate
conversion to that character set occurs. For input binary string data
(indicated by `MYSQL_TYPE_BLOB'), the value is treated as having the
`binary' character set; that is, it is treated as a byte string and no
conversion occurs.

To determine whether output string values in a result set returned from
the server contain binary or non-binary data, check whether the
`charsetnr' value of the result set metadata is 63 (see *Note
c-api-datatypes::). If so, the character set is `binary', which
indicates binary rather than non-binary data. This enables you to
distinguish *Note `BINARY': binary-varbinary. from *Note `CHAR': char,
*Note `VARBINARY': binary-varbinary. from *Note `VARCHAR': char, and the
*Note `BLOB': blob. types from the *Note `TEXT': blob. types.


File: manual.info,  Node: c-api-prepared-statement-function-overview,  Next: c-api-prepared-statement-functions,  Prev: c-api-prepared-statement-datatypes,  Up: c

20.10.6 C API Prepared Statement Function Overview
--------------------------------------------------

The functions available for prepared statement processing are
summarized here and described in greater detail in a later section. See
*Note c-api-prepared-statement-functions::.

*Function*              *Description*
*Note                   Returns the number of rows changed, deleted, or
`mysql_stmt_affected_rows()':inserted by prepared *Note `UPDATE': update,
mysql-stmt-affected-rows.*Note `DELETE': delete, or *Note `INSERT':
                        insert. statement
*Note                   Get value of an attribute for a prepared
`mysql_stmt_attr_get()':statement
mysql-stmt-attr-get.    
*Note                   Sets an attribute for a prepared statement
`mysql_stmt_attr_set()':
mysql-stmt-attr-set.    
*Note                   Associates application data buffers with the
`mysql_stmt_bind_param()':parameter markers in a prepared SQL statement
mysql-stmt-bind-param.  
*Note                   Associates application data buffers with columns
`mysql_stmt_bind_result()':in the result set
mysql-stmt-bind-result. 
*Note                   Frees memory used by prepared statement
`mysql_stmt_close()':   
mysql-stmt-close.       
*Note                   Seeks to an arbitrary row number in a statement
`mysql_stmt_data_seek()':result set
mysql-stmt-data-seek.   
*Note                   Returns the error number for the last statement
`mysql_stmt_errno()':   execution
mysql-stmt-errno.       
*Note                   Returns the error message for the last statement
`mysql_stmt_error()':   execution
mysql-stmt-error.       
*Note                   Executes the prepared statement
`mysql_stmt_execute()': 
mysql-stmt-execute.     
*Note                   Fetches the next row of data from the result set
`mysql_stmt_fetch()':   and returns data for all bound columns
mysql-stmt-fetch.       
*Note                   Fetch data for one column of the current row of
`mysql_stmt_fetch_column()':the result set
mysql-stmt-fetch-column.
*Note                   Returns the number of result columns for the
`mysql_stmt_field_count()':most recent statement
mysql-stmt-field-count. 
*Note                   Free the resources allocated to the statement
`mysql_stmt_free_result()':handle
mysql-stmt-free-result. 
*Note                   Allocates memory for `MYSQL_STMT' structure and
`mysql_stmt_init()':    initializes it
mysql-stmt-init.        
*Note                   Returns the ID generated for an `AUTO_INCREMENT'
`mysql_stmt_insert_id()':column by prepared statement
mysql-stmt-insert-id.   
*Note                   Returns/initiates the next result in
`mysql_stmt_next_result()':multiple-result executions
mysql-stmt-next-result. 
*Note                   Returns total row count from the buffered
`mysql_stmt_num_rows()':statement result set
mysql-stmt-num-rows.    
*Note                   Returns the number of parameters in a prepared
`mysql_stmt_param_count()':SQL statement
mysql-stmt-param-count. 
*Note                   (Return parameter metadata in the form of a
`mysql_stmt_param_metadata()':result set.) Currently, this function does
mysql-stmt-param-metadata.nothing
*Note                   Prepares an SQL string for execution
`mysql_stmt_prepare()': 
mysql-stmt-prepare.     
*Note                   Reset the statement buffers in the server
`mysql_stmt_reset()':   
mysql-stmt-reset.       
*Note                   Returns prepared statement metadata in the form
`mysql_stmt_result_metadata()':of a result set
mysql-stmt-result-metadata.
*Note                   Seeks to a row offset in a statement result set,
`mysql_stmt_row_seek()':using value returned from *Note
mysql-stmt-row-seek.    `mysql_stmt_row_tell()': mysql-stmt-row-tell.
*Note                   Returns the statement row cursor position
`mysql_stmt_row_tell()':
mysql-stmt-row-tell.    
*Note                   Sends long data in chunks to server
`mysql_stmt_send_long_data()':
mysql-stmt-send-long-data.
*Note                   Returns the SQLSTATE error code for the last
`mysql_stmt_sqlstate()':statement execution
mysql-stmt-sqlstate.    
*Note                   Retrieves the complete result set to the client
`mysql_stmt_store_result()':
mysql-stmt-store-result.

Call *Note `mysql_stmt_init()': mysql-stmt-init. to create a statement
handle, then *Note `mysql_stmt_prepare()': mysql-stmt-prepare. to
prepare it, *Note `mysql_stmt_bind_param()': mysql-stmt-bind-param. to
supply the parameter data, and *Note `mysql_stmt_execute()':
mysql-stmt-execute. to execute the statement. You can repeat the *Note
`mysql_stmt_execute()': mysql-stmt-execute. by changing parameter
values in the respective buffers supplied through *Note
`mysql_stmt_bind_param()': mysql-stmt-bind-param.

If the statement is a *Note `SELECT': select. or any other statement
that produces a result set, *Note `mysql_stmt_prepare()':
mysql-stmt-prepare. also returns the result set metadata information in
the form of a `MYSQL_RES' result set through *Note
`mysql_stmt_result_metadata()': mysql-stmt-result-metadata.

You can supply the result buffers using *Note
`mysql_stmt_bind_result()': mysql-stmt-bind-result, so that the *Note
`mysql_stmt_fetch()': mysql-stmt-fetch.  automatically returns data to
these buffers. This is row-by-row fetching.

You can also send the text or binary data in chunks to server using
*Note `mysql_stmt_send_long_data()': mysql-stmt-send-long-data.  See
*Note mysql-stmt-send-long-data::.

When statement execution has been completed, the statement handle must
be closed using *Note `mysql_stmt_close()': mysql-stmt-close. so that
all resources associated with it can be freed.

If you obtained a *Note `SELECT': select.  statement's result set
metadata by calling *Note `mysql_stmt_result_metadata()':
mysql-stmt-result-metadata, you should also free the metadata using
*Note `mysql_free_result()': mysql-free-result.

*Execution Steps*

To prepare and execute a statement, an application follows these steps:

  1. Create a prepared statement handle with *Note `mysql_stmt_init()':
     mysql-stmt-init. To prepare the statement on the server, call
     *Note `mysql_stmt_prepare()': mysql-stmt-prepare. and pass it a
     string containing the SQL statement.

  2. If the statement produces a result set, call *Note
     `mysql_stmt_result_metadata()': mysql-stmt-result-metadata.  to
     obtain the result set metadata. This metadata is itself in the
     form of result set, albeit a separate one from the one that
     contains the rows returned by the query. The metadata result set
     indicates how many columns are in the result and contains
     information about each column.

  3. Set the values of any parameters using *Note
     `mysql_stmt_bind_param()': mysql-stmt-bind-param. All parameters
     must be set. Otherwise, statement execution returns an error or
     produces unexpected results.

  4. Call *Note `mysql_stmt_execute()': mysql-stmt-execute. to execute
     the statement.

  5. If the statement produces a result set, bind the data buffers to
     use for retrieving the row values by calling *Note
     `mysql_stmt_bind_result()': mysql-stmt-bind-result.

  6. Fetch the data into the buffers row by row by calling *Note
     `mysql_stmt_fetch()': mysql-stmt-fetch. repeatedly until no more
     rows are found.

  7. Repeat steps 3 through 6 as necessary, by changing the parameter
     values and re-executing the statement.

When *Note `mysql_stmt_prepare()': mysql-stmt-prepare. is called, the
MySQL client/server protocol performs these actions:

   * The server parses the statement and sends the okay status back to
     the client by assigning a statement ID. It also sends total number
     of parameters, a column count, and its metadata if it is a result
     set oriented statement. All syntax and semantics of the statement
     are checked by the server during this call.

   * The client uses this statement ID for the further operations, so
     that the server can identify the statement from among its pool of
     statements.

When *Note `mysql_stmt_execute()': mysql-stmt-execute. is called, the
MySQL client/server protocol performs these actions:

   * The client uses the statement handle and sends the parameter data
     to the server.

   * The server identifies the statement using the ID provided by the
     client, replaces the parameter markers with the newly supplied
     data, and executes the statement. If the statement produces a
     result set, the server sends the data back to the client.
     Otherwise, it sends an okay status and total number of rows
     changed, deleted, or inserted.

When *Note `mysql_stmt_fetch()': mysql-stmt-fetch. is called, the MySQL
client/server protocol performs these actions:

   * The client reads the data from the packet row by row and places it
     into the application data buffers by doing the necessary
     conversions. If the application buffer type is same as that of the
     field type returned from the server, the conversions are
     straightforward.

If an error occurs, you can get the statement error code, error
message, and SQLSTATE value using *Note `mysql_stmt_errno()':
mysql-stmt-errno, *Note `mysql_stmt_error()': mysql-stmt-error, and
*Note `mysql_stmt_sqlstate()': mysql-stmt-sqlstate, respectively.

*Prepared Statement Logging*

For prepared statements that are executed with the *Note
`mysql_stmt_prepare()': mysql-stmt-prepare. and *Note
`mysql_stmt_execute()': mysql-stmt-execute. C API functions, the server
writes `Prepare' and `Execute' lines to the general query log so that
you can tell when statements are prepared and executed.

Suppose that you prepare and execute a statement as follows:

  1. Call *Note `mysql_stmt_prepare()': mysql-stmt-prepare. to prepare
     the statement string `"SELECT ?"'.

  2. Call *Note `mysql_stmt_bind_param()': mysql-stmt-bind-param.  to
     bind the value `3' to the parameter in the prepared statement.

  3. Call *Note `mysql_stmt_execute()': mysql-stmt-execute. to execute
     the prepared statement.

As a result of the preceding calls, the server writes the following
lines to the general query log:

     Prepare  [1] SELECT ?
     Execute  [1] SELECT 3

Each `Prepare' and `Execute' line in the log is tagged with a `[N]'
statement identifier so that you can keep track of which prepared
statement is being logged. N is a positive integer. If there are
multiple prepared statements active simultaneously for the client, N
may be greater than 1. Each `Execute' lines shows a prepared statement
after substitution of data values for `?' parameters.

Version notes: `Prepare' lines are displayed without `[N]' before MySQL
4.1.10. `Execute' lines are not displayed at all before MySQL 4.1.10.


File: manual.info,  Node: c-api-prepared-statement-functions,  Next: c-thread-functions,  Prev: c-api-prepared-statement-function-overview,  Up: c

20.10.7 C API Prepared Statement Function Descriptions
------------------------------------------------------

* Menu:

* mysql-stmt-affected-rows::     `mysql_stmt_affected_rows()'
* mysql-stmt-attr-get::          `mysql_stmt_attr_get()'
* mysql-stmt-attr-set::          `mysql_stmt_attr_set()'
* mysql-stmt-bind-param::        `mysql_stmt_bind_param()'
* mysql-stmt-bind-result::       `mysql_stmt_bind_result()'
* mysql-stmt-close::             `mysql_stmt_close()'
* mysql-stmt-data-seek::         `mysql_stmt_data_seek()'
* mysql-stmt-errno::             `mysql_stmt_errno()'
* mysql-stmt-error::             `mysql_stmt_error()'
* mysql-stmt-execute::           `mysql_stmt_execute()'
* mysql-stmt-fetch::             `mysql_stmt_fetch()'
* mysql-stmt-fetch-column::      `mysql_stmt_fetch_column()'
* mysql-stmt-field-count::       `mysql_stmt_field_count()'
* mysql-stmt-free-result::       `mysql_stmt_free_result()'
* mysql-stmt-init::              `mysql_stmt_init()'
* mysql-stmt-insert-id::         `mysql_stmt_insert_id()'
* mysql-stmt-next-result::       `mysql_stmt_next_result()'
* mysql-stmt-num-rows::          `mysql_stmt_num_rows()'
* mysql-stmt-param-count::       `mysql_stmt_param_count()'
* mysql-stmt-param-metadata::    `mysql_stmt_param_metadata()'
* mysql-stmt-prepare::           `mysql_stmt_prepare()'
* mysql-stmt-reset::             `mysql_stmt_reset()'
* mysql-stmt-result-metadata::   `mysql_stmt_result_metadata()'
* mysql-stmt-row-seek::          `mysql_stmt_row_seek()'
* mysql-stmt-row-tell::          `mysql_stmt_row_tell()'
* mysql-stmt-send-long-data::    `mysql_stmt_send_long_data()'
* mysql-stmt-sqlstate::          `mysql_stmt_sqlstate()'
* mysql-stmt-store-result::      `mysql_stmt_store_result()'

To prepare and execute queries, use the functions described in detail
in the following sections.

All functions that operate with a `MYSQL_STMT' structure begin with the
prefix `mysql_stmt_'.

To create a `MYSQL_STMT' handle, use the *Note `mysql_stmt_init()':
mysql-stmt-init. function.


File: manual.info,  Node: mysql-stmt-affected-rows,  Next: mysql-stmt-attr-get,  Prev: c-api-prepared-statement-functions,  Up: c-api-prepared-statement-functions

20.10.7.1 `mysql_stmt_affected_rows()'
......................................

`my_ulonglong mysql_stmt_affected_rows(MYSQL_STMT *stmt)'

*Description*

Returns the total number of rows changed, deleted, or inserted by the
last executed statement. May be called immediately after *Note
`mysql_stmt_execute()': mysql-stmt-execute. for *Note `UPDATE': update,
*Note `DELETE': delete, or *Note `INSERT': insert. statements. For
*Note `SELECT': select. statements, *Note `mysql_stmt_affected_rows()':
mysql-stmt-affected-rows. works like *Note `mysql_num_rows()':
mysql-num-rows.

*Return Values*

An integer greater than zero indicates the number of rows affected or
retrieved. Zero indicates that no records were updated for an *Note
`UPDATE': update. statement, no rows matched the `WHERE' clause in the
query, or that no query has yet been executed. -1 indicates that the
query returned an error or that, for a *Note `SELECT': select. query,
*Note `mysql_stmt_affected_rows()': mysql-stmt-affected-rows. was
called prior to calling *Note `mysql_stmt_store_result()':
mysql-stmt-store-result.  Because *Note `mysql_stmt_affected_rows()':
mysql-stmt-affected-rows.  returns an unsigned value, you can check for
-1 by comparing the return value to `(my_ulonglong)-1' (or to
`(my_ulonglong)~0', which is equivalent).

See *Note mysql-affected-rows::, for additional information on the
return value.

*Errors*

None.

*Example*

For the usage of *Note `mysql_stmt_affected_rows()':
mysql-stmt-affected-rows, refer to the Example from *Note
mysql-stmt-execute::.


File: manual.info,  Node: mysql-stmt-attr-get,  Next: mysql-stmt-attr-set,  Prev: mysql-stmt-affected-rows,  Up: c-api-prepared-statement-functions

20.10.7.2 `mysql_stmt_attr_get()'
.................................

`my_bool mysql_stmt_attr_get(MYSQL_STMT *stmt, enum enum_stmt_attr_type
option, void *arg)'

*Description*

Can be used to get the current value for a statement attribute.

The `option' argument is the option that you want to get; the `arg'
should point to a variable that should contain the option value. If the
option is an integer, then `arg' should point to the value of the
integer.

See *Note mysql-stmt-attr-set::, for a list of options and option types.

*Note*:

In MySQL 6.0, *Note `mysql_stmt_attr_get()': mysql-stmt-attr-get.
originally used `unsigned int *', not `my_bool *', for
`STMT_ATTR_UPDATE_MAX_LENGTH'.

*Return Values*

Zero if successful. Non-zero if `option' is unknown.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-attr-set,  Next: mysql-stmt-bind-param,  Prev: mysql-stmt-attr-get,  Up: c-api-prepared-statement-functions

20.10.7.3 `mysql_stmt_attr_set()'
.................................

`my_bool mysql_stmt_attr_set(MYSQL_STMT *stmt, enum enum_stmt_attr_type
option, const void *arg)'

*Description*

Can be used to affect behavior for a prepared statement. This function
may be called multiple times to set several options.

The `option' argument is the option that you want to set. The `arg'
argument is the value for the option. `arg' should point to a variable
that is set to the desired attribute value. The variable type is as
indicated in the following table.

The following table shows the possible `option' values.

*Option*                       *Argument      *Function*
                               Type*          
`STMT_ATTR_UPDATE_MAX_LENGTH'  `my_bool *'    If set to 1, causes *Note
                                              `mysql_stmt_store_result()':
                                              mysql-stmt-store-result.
                                              to update the metadata
                                              `MYSQL_FIELD->max_length'
                                              value.
`STMT_ATTR_CURSOR_TYPE'        `unsigned      Type of cursor to open for
                               long *'        statement when *Note
                                              `mysql_stmt_execute()':
                                              mysql-stmt-execute. is
                                              invoked. `*arg' can be
                                              `CURSOR_TYPE_NO_CURSOR'
                                              (the default) or
                                              `CURSOR_TYPE_READ_ONLY'.
`STMT_ATTR_PREFETCH_ROWS'      `unsigned      Number of rows to fetch
                               long *'        from server at a time when
                                              using a cursor.  `*arg'
                                              can be in the range from 1
                                              to the maximum value of
                                              `unsigned long'.  The
                                              default is 1.

If you use the `STMT_ATTR_CURSOR_TYPE' option with
`CURSOR_TYPE_READ_ONLY', a cursor is opened for the statement when you
invoke *Note `mysql_stmt_execute()': mysql-stmt-execute. If there is
already an open cursor from a previous *Note `mysql_stmt_execute()':
mysql-stmt-execute. call, it closes the cursor before opening a new one.
*Note `mysql_stmt_reset()': mysql-stmt-reset. also closes any open
cursor before preparing the statement for re-execution.  *Note
`mysql_stmt_free_result()': mysql-stmt-free-result. closes any open
cursor.

If you open a cursor for a prepared statement, *Note
`mysql_stmt_store_result()': mysql-stmt-store-result. is unnecessary,
because that function causes the result set to be buffered on the
client side.

*Return Values*

Zero if successful. Non-zero if `option' is unknown.

*Errors*

None.

*Example*

The following example opens a cursor for a prepared statement and sets
the number of rows to fetch at a time to 5:

     MYSQL_STMT *stmt;
     int rc;
     unsigned long type;
     unsigned long prefetch_rows = 5;

     stmt = mysql_stmt_init(mysql);
     type = (unsigned long) CURSOR_TYPE_READ_ONLY;
     rc = mysql_stmt_attr_set(stmt, STMT_ATTR_CURSOR_TYPE, (void*) &type);
     /* ... check return value ... */
     rc = mysql_stmt_attr_set(stmt, STMT_ATTR_PREFETCH_ROWS,
                              (void*) &prefetch_rows);
     /* ... check return value ... */


File: manual.info,  Node: mysql-stmt-bind-param,  Next: mysql-stmt-bind-result,  Prev: mysql-stmt-attr-set,  Up: c-api-prepared-statement-functions

20.10.7.4 `mysql_stmt_bind_param()'
...................................

`my_bool mysql_stmt_bind_param(MYSQL_STMT *stmt, MYSQL_BIND *bind)'

*Description*

*Note `mysql_stmt_bind_param()': mysql-stmt-bind-param. is used to bind
input data for the parameter markers in the SQL statement that was
passed to *Note `mysql_stmt_prepare()': mysql-stmt-prepare. It uses
`MYSQL_BIND' structures to supply the data.  `bind' is the address of
an array of `MYSQL_BIND' structures. The client library expects the
array to contain one element for each ``?'' parameter marker that is
present in the query.

Suppose that you prepare the following statement:

     INSERT INTO mytbl VALUES(?,?,?)

When you bind the parameters, the array of `MYSQL_BIND' structures must
contain three elements, and can be declared like this:

     MYSQL_BIND bind[3];

*Note c-api-prepared-statement-datatypes::, describes the members of
each `MYSQL_BIND' element and how they should be set to provide input
values.

*Return Values*

Zero if the bind operation was successful. Non-zero if an error
occurred.

*Errors*

   * `CR_UNSUPPORTED_PARAM_TYPE'

     The conversion is not supported. Possibly the `buffer_type' value
     is illegal or is not one of the supported types.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

For the usage of *Note `mysql_stmt_bind_param()':
mysql-stmt-bind-param, refer to the Example from *Note
mysql-stmt-execute::.


File: manual.info,  Node: mysql-stmt-bind-result,  Next: mysql-stmt-close,  Prev: mysql-stmt-bind-param,  Up: c-api-prepared-statement-functions

20.10.7.5 `mysql_stmt_bind_result()'
....................................

`my_bool mysql_stmt_bind_result(MYSQL_STMT *stmt, MYSQL_BIND *bind)'

*Description*

*Note `mysql_stmt_bind_result()': mysql-stmt-bind-result. is used to
associate (that is, bind) output columns in the result set to data
buffers and length buffers. When *Note `mysql_stmt_fetch()':
mysql-stmt-fetch. is called to fetch data, the MySQL client/server
protocol places the data for the bound columns into the specified
buffers.

All columns must be bound to buffers prior to calling *Note
`mysql_stmt_fetch()': mysql-stmt-fetch.  `bind' is the address of an
array of `MYSQL_BIND' structures. The client library expects the array
to contain one element for each column of the result set. If you do not
bind columns to `MYSQL_BIND' structures, *Note `mysql_stmt_fetch()':
mysql-stmt-fetch. simply ignores the data fetch. The buffers should be
large enough to hold the data values, because the protocol doesn't
return data values in chunks.

A column can be bound or rebound at any time, even after a result set
has been partially retrieved. The new binding takes effect the next time
*Note `mysql_stmt_fetch()': mysql-stmt-fetch. is called.  Suppose that
an application binds the columns in a result set and calls *Note
`mysql_stmt_fetch()': mysql-stmt-fetch.  The client/server protocol
returns data in the bound buffers.  Then suppose that the application
binds the columns to a different set of buffers. The protocol places
data into the newly bound buffers when the next call to *Note
`mysql_stmt_fetch()': mysql-stmt-fetch. occurs.

To bind a column, an application calls *Note
`mysql_stmt_bind_result()': mysql-stmt-bind-result. and passes the
type, address, and length of the output buffer into which the value
should be stored.  *Note c-api-prepared-statement-datatypes::, describes
the members of each `MYSQL_BIND' element and how they should be set to
receive output values.

*Return Values*

Zero if the bind operation was successful. Non-zero if an error
occurred.

*Errors*

   * `CR_UNSUPPORTED_PARAM_TYPE'

     The conversion is not supported. Possibly the `buffer_type' value
     is illegal or is not one of the supported types.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

For the usage of *Note `mysql_stmt_bind_result()':
mysql-stmt-bind-result, refer to the Example from *Note
mysql-stmt-fetch::.


File: manual.info,  Node: mysql-stmt-close,  Next: mysql-stmt-data-seek,  Prev: mysql-stmt-bind-result,  Up: c-api-prepared-statement-functions

20.10.7.6 `mysql_stmt_close()'
..............................

`my_bool mysql_stmt_close(MYSQL_STMT *)'

*Description*

Closes the prepared statement.  *Note `mysql_stmt_close()':
mysql-stmt-close. also deallocates the statement handle pointed to by
`stmt'.

If the current statement has pending or unread results, this function
cancels them so that the next query can be executed.

*Return Values*

Zero if the statement was freed successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

For the usage of *Note `mysql_stmt_close()': mysql-stmt-close, refer to
the Example from *Note mysql-stmt-execute::.


File: manual.info,  Node: mysql-stmt-data-seek,  Next: mysql-stmt-errno,  Prev: mysql-stmt-close,  Up: c-api-prepared-statement-functions

20.10.7.7 `mysql_stmt_data_seek()'
..................................

`void mysql_stmt_data_seek(MYSQL_STMT *stmt, my_ulonglong offset)'

*Description*

Seeks to an arbitrary row in a statement result set. The `offset' value
is a row number and should be in the range from `0' to *Note
`mysql_stmt_num_rows(stmt)-1': mysql-stmt-num-rows.

This function requires that the statement result set structure contains
the entire result of the last executed query, so *Note
`mysql_stmt_data_seek()': mysql-stmt-data-seek. may be used only in
conjunction with *Note `mysql_stmt_store_result()':
mysql-stmt-store-result.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-errno,  Next: mysql-stmt-error,  Prev: mysql-stmt-data-seek,  Up: c-api-prepared-statement-functions

20.10.7.8 `mysql_stmt_errno()'
..............................

`unsigned int mysql_stmt_errno(MYSQL_STMT *stmt)'

*Description*

For the statement specified by `stmt', *Note `mysql_stmt_errno()':
mysql-stmt-errno. returns the error code for the most recently invoked
statement API function that can succeed or fail. A return value of zero
means that no error occurred. Client error message numbers are listed
in the MySQL `errmsg.h' header file. Server error message numbers are
listed in `mysqld_error.h'. Errors also are listed at *Note
error-handling::.

*Return Values*

An error code value. Zero if no error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-error,  Next: mysql-stmt-execute,  Prev: mysql-stmt-errno,  Up: c-api-prepared-statement-functions

20.10.7.9 `mysql_stmt_error()'
..............................

`const char *mysql_stmt_error(MYSQL_STMT *stmt)'

*Description*

For the statement specified by `stmt', *Note `mysql_stmt_error()':
mysql-stmt-error. returns a null-terminated string containing the error
message for the most recently invoked statement API function that can
succeed or fail. An empty string (`""') is returned if no error
occurred. This means the following two tests are equivalent:

     if(*mysql_stmt_errno(stmt))
     {
       // an error occurred
     }

     if (mysql_stmt_error(stmt)[0])
     {
       // an error occurred
     }

The language of the client error messages may be changed by recompiling
the MySQL client library. Currently, you can choose error messages in
several different languages.

*Return Values*

A character string that describes the error. An empty string if no
error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-execute,  Next: mysql-stmt-fetch,  Prev: mysql-stmt-error,  Up: c-api-prepared-statement-functions

20.10.7.10 `mysql_stmt_execute()'
.................................

`int mysql_stmt_execute(MYSQL_STMT *stmt)'

*Description*

*Note `mysql_stmt_execute()': mysql-stmt-execute. executes the prepared
query associated with the statement handle. The currently bound
parameter marker values are sent to server during this call, and the
server replaces the markers with this newly supplied data.

If the statement is an *Note `UPDATE': update, *Note `DELETE': delete,
or *Note `INSERT': insert, the total number of changed, deleted, or
inserted rows can be found by calling *Note
`mysql_stmt_affected_rows()': mysql-stmt-affected-rows. If this is a
statement such as *Note `SELECT': select. that generates a result set,
you must call *Note `mysql_stmt_fetch()': mysql-stmt-fetch. to fetch the
data prior to calling any other functions that result in query
processing. For more information on how to fetch the results, refer to
*Note mysql-stmt-fetch::.

For statements that generate a result set, you can request that *Note
`mysql_stmt_execute()': mysql-stmt-execute. open a cursor for the
statement by calling *Note `mysql_stmt_attr_set()':
mysql-stmt-attr-set. before executing the statement. If you execute a
statement multiple times, *Note `mysql_stmt_execute()':
mysql-stmt-execute.  closes any open cursor before opening a new one.

As of MySQL 6.0.6, metadata changes to tables or views referred to by
prepared statements are detected and cause automatic repreparation of
the statement when it is next executed. For more information, see *Note
statement-repreparation::.

*Return Values*

Zero if execution was successful. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

The following example demonstrates how to create and populate a table
using *Note `mysql_stmt_init()': mysql-stmt-init, *Note
`mysql_stmt_prepare()': mysql-stmt-prepare, *Note
`mysql_stmt_param_count()': mysql-stmt-param-count, *Note
`mysql_stmt_bind_param()': mysql-stmt-bind-param, *Note
`mysql_stmt_execute()': mysql-stmt-execute, and *Note
`mysql_stmt_affected_rows()': mysql-stmt-affected-rows. The `mysql'
variable is assumed to be a valid connection handle.

     #define STRING_SIZE 50

     #define DROP_SAMPLE_TABLE "DROP TABLE IF EXISTS test_table"
     #define CREATE_SAMPLE_TABLE "CREATE TABLE test_table(col1 INT,\
                                                      col2 VARCHAR(40),\
                                                      col3 SMALLINT,\
                                                      col4 TIMESTAMP)"
     #define INSERT_SAMPLE "INSERT INTO \
                            test_table(col1,col2,col3) \
                            VALUES(?,?,?)"

     MYSQL_STMT    *stmt;
     MYSQL_BIND    bind[3];
     my_ulonglong  affected_rows;
     int           param_count;
     short         small_data;
     int           int_data;
     char          str_data[STRING_SIZE];
     unsigned long str_length;
     my_bool       is_null;

     if (mysql_query(mysql, DROP_SAMPLE_TABLE))
     {
       fprintf(stderr, " DROP TABLE failed\n");
       fprintf(stderr, " %s\n", mysql_error(mysql));
       exit(0);
     }

     if (mysql_query(mysql, CREATE_SAMPLE_TABLE))
     {
       fprintf(stderr, " CREATE TABLE failed\n");
       fprintf(stderr, " %s\n", mysql_error(mysql));
       exit(0);
     }

     /* Prepare an INSERT query with 3 parameters */
     /* (the TIMESTAMP column is not named; the server */
     /*  sets it to the current date and time) */
     stmt = mysql_stmt_init(mysql);
     if (!stmt)
     {
       fprintf(stderr, " mysql_stmt_init(), out of memory\n");
       exit(0);
     }
     if (mysql_stmt_prepare(stmt, INSERT_SAMPLE, strlen(INSERT_SAMPLE)))
     {
       fprintf(stderr, " mysql_stmt_prepare(), INSERT failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }
     fprintf(stdout, " prepare, INSERT successful\n");

     /* Get the parameter count from the statement */
     param_count= mysql_stmt_param_count(stmt);
     fprintf(stdout, " total parameters in INSERT: %d\n", param_count);

     if (param_count != 3) /* validate parameter count */
     {
       fprintf(stderr, " invalid parameter count returned by MySQL\n");
       exit(0);
     }

     /* Bind the data for all 3 parameters */

     memset(bind, 0, sizeof(bind));

     /* INTEGER PARAM */
     /* This is a number type, so there is no need
        to specify buffer_length */
     bind[0].buffer_type= MYSQL_TYPE_LONG;
     bind[0].buffer= (char *)&int_data;
     bind[0].is_null= 0;
     bind[0].length= 0;

     /* STRING PARAM */
     bind[1].buffer_type= MYSQL_TYPE_STRING;
     bind[1].buffer= (char *)str_data;
     bind[1].buffer_length= STRING_SIZE;
     bind[1].is_null= 0;
     bind[1].length= &str_length;

     /* SMALLINT PARAM */
     bind[2].buffer_type= MYSQL_TYPE_SHORT;
     bind[2].buffer= (char *)&small_data;
     bind[2].is_null= &is_null;
     bind[2].length= 0;

     /* Bind the buffers */
     if (mysql_stmt_bind_param(stmt, bind))
     {
       fprintf(stderr, " mysql_stmt_bind_param() failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Specify the data values for the first row */
     int_data= 10;             /* integer */
     strncpy(str_data, "MySQL", STRING_SIZE); /* string  */
     str_length= strlen(str_data);

     /* INSERT SMALLINT data as NULL */
     is_null= 1;

     /* Execute the INSERT statement - 1*/
     if (mysql_stmt_execute(stmt))
     {
       fprintf(stderr, " mysql_stmt_execute(), 1 failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Get the total number of affected rows */
     affected_rows= mysql_stmt_affected_rows(stmt);
     fprintf(stdout, " total affected rows(insert 1): %lu\n",
                     (unsigned long) affected_rows);

     if (affected_rows != 1) /* validate affected rows */
     {
       fprintf(stderr, " invalid affected rows by MySQL\n");
       exit(0);
     }

     /* Specify data values for second row,
        then re-execute the statement */
     int_data= 1000;
     strncpy(str_data, "
             The most popular Open Source database",
             STRING_SIZE);
     str_length= strlen(str_data);
     small_data= 1000;         /* smallint */
     is_null= 0;               /* reset */

     /* Execute the INSERT statement - 2*/
     if (mysql_stmt_execute(stmt))
     {
       fprintf(stderr, " mysql_stmt_execute, 2 failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Get the total rows affected */
     affected_rows= mysql_stmt_affected_rows(stmt);
     fprintf(stdout, " total affected rows(insert 2): %lu\n",
                     (unsigned long) affected_rows);

     if (affected_rows != 1) /* validate affected rows */
     {
       fprintf(stderr, " invalid affected rows by MySQL\n");
       exit(0);
     }

     /* Close the statement */
     if (mysql_stmt_close(stmt))
     {
       fprintf(stderr, " failed while closing the statement\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

*Note*:

For complete examples on the use of prepared statement functions, refer
to the file `tests/mysql_client_test.c'. This file can be obtained from
a MySQL source distribution or from the Bazaar source repository.


File: manual.info,  Node: mysql-stmt-fetch,  Next: mysql-stmt-fetch-column,  Prev: mysql-stmt-execute,  Up: c-api-prepared-statement-functions

20.10.7.11 `mysql_stmt_fetch()'
...............................

`int mysql_stmt_fetch(MYSQL_STMT *stmt)'

*Description*

*Note `mysql_stmt_fetch()': mysql-stmt-fetch. returns the next row in
the result set. It can be called only while the result set exists; that
is, after a call to *Note `mysql_stmt_execute()': mysql-stmt-execute.
for a statement such as *Note `SELECT': select. that creates a result
set.

*Note `mysql_stmt_fetch()': mysql-stmt-fetch. returns row data using
the buffers bound by *Note `mysql_stmt_bind_result()':
mysql-stmt-bind-result. It returns the data in those buffers for all
the columns in the current row set and the lengths are returned to the
`length' pointer. All columns must be bound by the application before
it calls *Note `mysql_stmt_fetch()': mysql-stmt-fetch.

By default, result sets are fetched unbuffered a row at a time from the
server. To buffer the entire result set on the client, call *Note
`mysql_stmt_store_result()': mysql-stmt-store-result.  after binding
the data buffers and before caling *Note `mysql_stmt_fetch()':
mysql-stmt-fetch.

If a fetched data value is a `NULL' value, the `*is_null' value of the
corresponding `MYSQL_BIND' structure contains TRUE (1).  Otherwise, the
data and its length are returned in the `*buffer' and `*length'
elements based on the buffer type specified by the application.  Each
numeric and temporal type has a fixed length, as listed in the
following table. The length of the string types depends on the length
of the actual data value, as indicated by `data_length'.

*Type*                               *Length*
`MYSQL_TYPE_TINY'                    1
`MYSQL_TYPE_SHORT'                   2
`MYSQL_TYPE_LONG'                    4
`MYSQL_TYPE_LONGLONG'                8
`MYSQL_TYPE_FLOAT'                   4
`MYSQL_TYPE_DOUBLE'                  8
`MYSQL_TYPE_TIME'                    `sizeof(MYSQL_TIME)'
`MYSQL_TYPE_DATE'                    `sizeof(MYSQL_TIME)'
`MYSQL_TYPE_DATETIME'                `sizeof(MYSQL_TIME)'
`MYSQL_TYPE_STRING'                  `data length'
`MYSQL_TYPE_BLOB'                    `data_length'

*Return Values*

*Return Value*            *Description*
0                         Successful, the data has been fetched to
                          application data buffers.
1                         Error occurred. Error code and message can be
                          obtained by calling *Note
                          `mysql_stmt_errno()': mysql-stmt-errno. and
                          *Note `mysql_stmt_error()': mysql-stmt-error.
`MYSQL_NO_DATA'           No more rows/data exists
`MYSQL_DATA_TRUNCATED'    Data truncation occurred

`MYSQL_DATA_TRUNCATED' is returned when truncation reporting is
enabled. (Reporting is enabled by default, but can be controlled with
*Note `mysql_options()': mysql-options.) To determine which parameters
were truncated when this value is returned, check the `error' members
of the `MYSQL_BIND' parameter structures.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

   * `CR_UNSUPPORTED_PARAM_TYPE'

     The buffer type is `MYSQL_TYPE_DATE', `MYSQL_TYPE_TIME',
     `MYSQL_TYPE_DATETIME', or `MYSQL_TYPE_TIMESTAMP', but the data type
     is not *Note `DATE': datetime, *Note `TIME': time, *Note
     `DATETIME': datetime, or *Note `TIMESTAMP': datetime.

   * All other unsupported conversion errors are returned from *Note
     `mysql_stmt_bind_result()': mysql-stmt-bind-result.

*Example*

The following example demonstrates how to fetch data from a table using
*Note `mysql_stmt_result_metadata()': mysql-stmt-result-metadata, *Note
`mysql_stmt_bind_result()': mysql-stmt-bind-result, and *Note
`mysql_stmt_fetch()': mysql-stmt-fetch. (This example expects to
retrieve the two rows inserted by the example shown in *Note
mysql-stmt-execute::.) The `mysql' variable is assumed to be a valid
connection handle.

     #define STRING_SIZE 50

     #define SELECT_SAMPLE "SELECT col1, col2, col3, col4 \
                            FROM test_table"

     MYSQL_STMT    *stmt;
     MYSQL_BIND    bind[4];
     MYSQL_RES     *prepare_meta_result;
     MYSQL_TIME    ts;
     unsigned long length[4];
     int           param_count, column_count, row_count;
     short         small_data;
     int           int_data;
     char          str_data[STRING_SIZE];
     my_bool       is_null[4];
     my_bool       error[4];

     /* Prepare a SELECT query to fetch data from test_table */
     stmt = mysql_stmt_init(mysql);
     if (!stmt)
     {
       fprintf(stderr, " mysql_stmt_init(), out of memory\n");
       exit(0);
     }
     if (mysql_stmt_prepare(stmt, SELECT_SAMPLE, strlen(SELECT_SAMPLE)))
     {
       fprintf(stderr, " mysql_stmt_prepare(), SELECT failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }
     fprintf(stdout, " prepare, SELECT successful\n");

     /* Get the parameter count from the statement */
     param_count= mysql_stmt_param_count(stmt);
     fprintf(stdout, " total parameters in SELECT: %d\n", param_count);

     if (param_count != 0) /* validate parameter count */
     {
       fprintf(stderr, " invalid parameter count returned by MySQL\n");
       exit(0);
     }

     /* Fetch result set meta information */
     prepare_meta_result = mysql_stmt_result_metadata(stmt);
     if (!prepare_meta_result)
     {
       fprintf(stderr,
              " mysql_stmt_result_metadata(), \
                returned no meta information\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Get total columns in the query */
     column_count= mysql_num_fields(prepare_meta_result);
     fprintf(stdout,
             " total columns in SELECT statement: %d\n",
             column_count);

     if (column_count != 4) /* validate column count */
     {
       fprintf(stderr, " invalid column count returned by MySQL\n");
       exit(0);
     }

     /* Execute the SELECT query */
     if (mysql_stmt_execute(stmt))
     {
       fprintf(stderr, " mysql_stmt_execute(), failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Bind the result buffers for all 4 columns before fetching them */

     memset(bind, 0, sizeof(bind));

     /* INTEGER COLUMN */
     bind[0].buffer_type= MYSQL_TYPE_LONG;
     bind[0].buffer= (char *)&int_data;
     bind[0].is_null= &is_null[0];
     bind[0].length= &length[0];
     bind[0].error= &error[0];

     /* STRING COLUMN */
     bind[1].buffer_type= MYSQL_TYPE_STRING;
     bind[1].buffer= (char *)str_data;
     bind[1].buffer_length= STRING_SIZE;
     bind[1].is_null= &is_null[1];
     bind[1].length= &length[1];
     bind[1].error= &error[1];

     /* SMALLINT COLUMN */
     bind[2].buffer_type= MYSQL_TYPE_SHORT;
     bind[2].buffer= (char *)&small_data;
     bind[2].is_null= &is_null[2];
     bind[2].length= &length[2];
     bind[2].error= &error[2];

     /* TIMESTAMP COLUMN */
     bind[3].buffer_type= MYSQL_TYPE_TIMESTAMP;
     bind[3].buffer= (char *)&ts;
     bind[3].is_null= &is_null[3];
     bind[3].length= &length[3];
     bind[3].error= &error[3];

     /* Bind the result buffers */
     if (mysql_stmt_bind_result(stmt, bind))
     {
       fprintf(stderr, " mysql_stmt_bind_result() failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Now buffer all results to client (optional step) */
     if (mysql_stmt_store_result(stmt))
     {
       fprintf(stderr, " mysql_stmt_store_result() failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Fetch all rows */
     row_count= 0;
     fprintf(stdout, "Fetching results ...\n");
     while (!mysql_stmt_fetch(stmt))
     {
       row_count++;
       fprintf(stdout, "  row %d\n", row_count);

       /* column 1 */
       fprintf(stdout, "   column1 (integer)  : ");
       if (is_null[0])
         fprintf(stdout, " NULL\n");
       else
         fprintf(stdout, " %d(%ld)\n", int_data, length[0]);

       /* column 2 */
       fprintf(stdout, "   column2 (string)   : ");
       if (is_null[1])
         fprintf(stdout, " NULL\n");
       else
         fprintf(stdout, " %s(%ld)\n", str_data, length[1]);

       /* column 3 */
       fprintf(stdout, "   column3 (smallint) : ");
       if (is_null[2])
         fprintf(stdout, " NULL\n");
       else
         fprintf(stdout, " %d(%ld)\n", small_data, length[2]);

       /* column 4 */
       fprintf(stdout, "   column4 (timestamp): ");
       if (is_null[3])
         fprintf(stdout, " NULL\n");
       else
         fprintf(stdout, " %04d-%02d-%02d %02d:%02d:%02d (%ld)\n",
                          ts.year, ts.month, ts.day,
                          ts.hour, ts.minute, ts.second,
                          length[3]);
       fprintf(stdout, "\n");
     }

     /* Validate rows fetched */
     fprintf(stdout, " total rows fetched: %d\n", row_count);
     if (row_count != 2)
     {
       fprintf(stderr, " MySQL failed to return all rows\n");
       exit(0);
     }

     /* Free the prepared result metadata */
     mysql_free_result(prepare_meta_result);

     /* Close the statement */
     if (mysql_stmt_close(stmt))
     {
       fprintf(stderr, " failed while closing the statement\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

In some cases you might want to determine the length of a column value
before fetching it with *Note `mysql_stmt_fetch()': mysql-stmt-fetch.
For example, the value might be a long string or *Note `BLOB': blob.
value for which you want to know how much space must be allocated. To
accomplish this, you can use these strategies:

   * Before invoking *Note `mysql_stmt_fetch()': mysql-stmt-fetch. to
     retrieve individual rows, invoke *Note
     `mysql_stmt_store_result()': mysql-stmt-store-result. to buffer
     the entire result on the client side. Then the maximal length of
     column values will be indicated by the `max_length' member of the
     result set metadata returned by *Note
     `mysql_stmt_result_metadata()': mysql-stmt-result-metadata.  This
     strategy requires that you pass `STMT_ATTR_UPDATE_MAX_LENGTH' to
     *Note `mysql_stmt_attr_set()': mysql-stmt-attr-set. or the
     `max_length' values will not be calculated.

   * Invoke *Note `mysql_stmt_fetch()': mysql-stmt-fetch.  with a
     zero-length buffer for the column in question and a pointer in
     which the real length can be stored. Then use the real length with
     *Note `mysql_stmt_fetch_column()': mysql-stmt-fetch-column.

          real_length= 0;

          bind[0].buffer= 0;
          bind[0].buffer_length= 0;
          bind[0].length= &real_length
          mysql_stmt_bind_result(stmt, bind);

          mysql_stmt_fetch(stmt);
          if (real_length > 0)
          {
            data= malloc(real_length);
            bind[0].buffer= data;
            bind[0].buffer_length= real_length;
            mysql_stmt_fetch_column(stmt, bind, 0, 0);
          }


File: manual.info,  Node: mysql-stmt-fetch-column,  Next: mysql-stmt-field-count,  Prev: mysql-stmt-fetch,  Up: c-api-prepared-statement-functions

20.10.7.12 `mysql_stmt_fetch_column()'
......................................

`int mysql_stmt_fetch_column(MYSQL_STMT *stmt, MYSQL_BIND *bind,
unsigned int column, unsigned long offset)'

*Description*

Fetch one column from the current result set row.  `bind' provides the
buffer where data should be placed. It should be set up the same way as
for *Note `mysql_stmt_bind_result()': mysql-stmt-bind-result.  `column'
indicates which column to fetch. The first column is numbered 0.
`offset' is the offset within the data value at which to begin
retrieving data.  This can be used for fetching the data value in
pieces. The beginning of the value is offset 0.

*Return Values*

Zero if the value was fetched successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_INVALID_PARAMETER_NO'

     Invalid column number.

   * `CR_NO_DATA'

     The end of the result set has already been reached.


File: manual.info,  Node: mysql-stmt-field-count,  Next: mysql-stmt-free-result,  Prev: mysql-stmt-fetch-column,  Up: c-api-prepared-statement-functions

20.10.7.13 `mysql_stmt_field_count()'
.....................................

`unsigned int mysql_stmt_field_count(MYSQL_STMT *stmt)'

*Description*

Returns the number of columns for the most recent statement for the
statement handler. This value is zero for statements such as *Note
`INSERT': insert. or *Note `DELETE': delete. that do not produce result
sets.

*Note `mysql_stmt_field_count()': mysql-stmt-field-count. can be called
after you have prepared a statement by invoking *Note
`mysql_stmt_prepare()': mysql-stmt-prepare.

*Return Values*

An unsigned integer representing the number of columns in a result set.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-free-result,  Next: mysql-stmt-init,  Prev: mysql-stmt-field-count,  Up: c-api-prepared-statement-functions

20.10.7.14 `mysql_stmt_free_result()'
.....................................

`my_bool mysql_stmt_free_result(MYSQL_STMT *stmt)'

*Description*

Releases memory associated with the result set produced by execution of
the prepared statement. If there is a cursor open for the statement,
*Note `mysql_stmt_free_result()': mysql-stmt-free-result. closes it.

*Return Values*

Zero if the result set was freed successfully. Non-zero if an error
occurred.

*Errors*


File: manual.info,  Node: mysql-stmt-init,  Next: mysql-stmt-insert-id,  Prev: mysql-stmt-free-result,  Up: c-api-prepared-statement-functions

20.10.7.15 `mysql_stmt_init()'
..............................

`MYSQL_STMT *mysql_stmt_init(MYSQL *mysql)'

*Description*

Create a `MYSQL_STMT' handle. The handle should be freed with *Note
`mysql_stmt_close(MYSQL_STMT *)': mysql-stmt-close.

*Return values*

A pointer to a `MYSQL_STMT' structure in case of success. `NULL' if out
of memory.

*Errors*

   * `CR_OUT_OF_MEMORY'

     Out of memory.


File: manual.info,  Node: mysql-stmt-insert-id,  Next: mysql-stmt-next-result,  Prev: mysql-stmt-init,  Up: c-api-prepared-statement-functions

20.10.7.16 `mysql_stmt_insert_id()'
...................................

`my_ulonglong mysql_stmt_insert_id(MYSQL_STMT *stmt)'

*Description*

Returns the value generated for an `AUTO_INCREMENT' column by the
prepared *Note `INSERT': insert. or *Note `UPDATE': update. statement.
Use this function after you have executed a prepared *Note `INSERT':
insert. statement on a table which contains an `AUTO_INCREMENT' field.

See *Note mysql-insert-id::, for more information.

*Return Values*

Value for `AUTO_INCREMENT' column which was automatically generated or
explicitly set during execution of prepared statement, or value
generated by `LAST_INSERT_ID(EXPR)' function. Return value is undefined
if statement does not set `AUTO_INCREMENT' value.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-next-result,  Next: mysql-stmt-num-rows,  Prev: mysql-stmt-insert-id,  Up: c-api-prepared-statement-functions

20.10.7.17 `mysql_stmt_next_result()'
.....................................

`int mysql_stmt_next_result(MYSQL *mysql)'

*Description*

This function is used when you use prepared *Note `CALL': call.
statements to execute stored procedures, which can return multiple
result sets. Use a loop that calls *Note `mysql_stmt_next_result()':
mysql-stmt-next-result. to determine whether there are more results. If
a procedure has `OUT' or `INOUT' parameters, their values will be
returned as a single-row result set following any other result sets.
The values will appear in the order in which they are declared in the
procedure parameter list.

*Note `mysql_stmt_next_result()': mysql-stmt-next-result. returns a
status to indicate whether more results exist. If *Note
`mysql_stmt_next_result()': mysql-stmt-next-result. returns an error,
there are no more results.

Before each call to *Note `mysql_stmt_next_result()':
mysql-stmt-next-result, you must call *Note `mysql_stmt_free_result()':
mysql-stmt-free-result. for the current result if it produced a result
set (rather than just a result status).

After calling *Note `mysql_stmt_next_result()': mysql-stmt-next-result.
the state of the connection is as if you had called *Note
`mysql_stmt_execute()': mysql-stmt-execute. This means that you can call
*Note `mysql_stmt_bind_result()': mysql-stmt-bind-result, *Note
`mysql_stmt_affected_rows()': mysql-stmt-affected-rows, and so forth.

It is also possible to test whether there are more results by calling
*Note `mysql_more_results()': mysql-more-results.  However, this
function does not change the connection state, so if it returns true,
you must still call *Note `mysql_stmt_next_result()':
mysql-stmt-next-result. to advance to the next result.

For an example that shows how to use *Note `mysql_stmt_next_result()':
mysql-stmt-next-result, see *Note c-api-prepared-call-statements::.

*Note `mysql_stmt_next_result()': mysql-stmt-next-result. was added in
MySQL 6.0.8.

*Return Values*

*Return Value*            *Description*
0                         Successful and there are more results
-1                        Successful and there are no more results
>0                        An error occurred

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-stmt-num-rows,  Next: mysql-stmt-param-count,  Prev: mysql-stmt-next-result,  Up: c-api-prepared-statement-functions

20.10.7.18 `mysql_stmt_num_rows()'
..................................

`my_ulonglong mysql_stmt_num_rows(MYSQL_STMT *stmt)'

*Description*

Returns the number of rows in the result set.

The use of *Note `mysql_stmt_num_rows()': mysql-stmt-num-rows.  depends
on whether you used *Note `mysql_stmt_store_result()':
mysql-stmt-store-result. to buffer the entire result set in the
statement handle.

If you use *Note `mysql_stmt_store_result()': mysql-stmt-store-result,
*Note `mysql_stmt_num_rows()': mysql-stmt-num-rows. may be called
immediately. Otherwise, the row count is unavailable unless you count
the rows as you fetch them.

*Note `mysql_stmt_num_rows()': mysql-stmt-num-rows. is intended for use
with statements that return a result set, such as *Note `SELECT':
select. For statements such as *Note `INSERT': insert, *Note `UPDATE':
update, or *Note `DELETE': delete, the number of affected rows can be
obtained with *Note `mysql_stmt_affected_rows()':
mysql-stmt-affected-rows.

*Return Values*

The number of rows in the result set.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-param-count,  Next: mysql-stmt-param-metadata,  Prev: mysql-stmt-num-rows,  Up: c-api-prepared-statement-functions

20.10.7.19 `mysql_stmt_param_count()'
.....................................

`unsigned long mysql_stmt_param_count(MYSQL_STMT *stmt)'

*Description*

Returns the number of parameter markers present in the prepared
statement.

*Return Values*

An unsigned long integer representing the number of parameters in a
statement.

*Errors*

None.

*Example*

For the usage of *Note `mysql_stmt_param_count()':
mysql-stmt-param-count, refer to the Example from *Note
mysql-stmt-execute::.


File: manual.info,  Node: mysql-stmt-param-metadata,  Next: mysql-stmt-prepare,  Prev: mysql-stmt-param-count,  Up: c-api-prepared-statement-functions

20.10.7.20 `mysql_stmt_param_metadata()'
........................................

`MYSQL_RES *mysql_stmt_param_metadata(MYSQL_STMT *stmt)'

This function currently does nothing.

*Description*

*Return Values*

*Errors*


File: manual.info,  Node: mysql-stmt-prepare,  Next: mysql-stmt-reset,  Prev: mysql-stmt-param-metadata,  Up: c-api-prepared-statement-functions

20.10.7.21 `mysql_stmt_prepare()'
.................................

`int mysql_stmt_prepare(MYSQL_STMT *stmt, const char *stmt_str,
unsigned long length)'

*Description*

Given the statement handle returned by *Note `mysql_stmt_init()':
mysql-stmt-init, prepares the SQL statement pointed to by the string
`stmt_str' and returns a status value. The string length should be
given by the `length' argument. The string must consist of a single SQL
statement. You should not add a terminating semicolon (``;'') or `\g'
to the statement.

The application can include one or more parameter markers in the SQL
statement by embedding question mark (``?'') characters into the SQL
string at the appropriate positions.

The markers are legal only in certain places in SQL statements.  For
example, they are allowed in the `VALUES()' list of an *Note `INSERT':
insert. statement (to specify column values for a row), or in a
comparison with a column in a `WHERE' clause to specify a comparison
value. However, they are not allowed for identifiers (such as table or
column names), or to specify both operands of a binary operator such as
the `=' equal sign.  The latter restriction is necessary because it
would be impossible to determine the parameter type. In general,
parameters are legal only in Data Manipulation Language (DML)
statements, and not in Data Definition Language (DDL) statements.

The parameter markers must be bound to application variables using
*Note `mysql_stmt_bind_param()': mysql-stmt-bind-param.  before
executing the statement.

As of MySQL 6.0.6, metadata changes to tables or views referred to by
prepared statements are detected and cause automatic repreparation of
the statement when it is next executed. For more information, see *Note
statement-repreparation::.

*Return Values*

Zero if the statement was prepared successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

If the prepare operation was unsuccessful (that is, *Note
`mysql_stmt_prepare()': mysql-stmt-prepare. returns non-zero), the
error message can be obtained by calling *Note `mysql_stmt_error()':
mysql-stmt-error.

*Example*

For the usage of *Note `mysql_stmt_prepare()': mysql-stmt-prepare,
refer to the Example from *Note mysql-stmt-execute::.


File: manual.info,  Node: mysql-stmt-reset,  Next: mysql-stmt-result-metadata,  Prev: mysql-stmt-prepare,  Up: c-api-prepared-statement-functions

20.10.7.22 `mysql_stmt_reset()'
...............................

`my_bool mysql_stmt_reset(MYSQL_STMT *stmt)'

*Description*

Reset the prepared statement on the client and server to state after
prepare. This is mainly used to reset data sent with *Note
`mysql_stmt_send_long_data()': mysql-stmt-send-long-data. Any open
cursor for the statement is closed.

To re-prepare the statement with another query, use *Note
`mysql_stmt_prepare()': mysql-stmt-prepare.

*Return Values*

Zero if the statement was reset successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-stmt-result-metadata,  Next: mysql-stmt-row-seek,  Prev: mysql-stmt-reset,  Up: c-api-prepared-statement-functions

20.10.7.23 `mysql_stmt_result_metadata()'
.........................................

`MYSQL_RES *mysql_stmt_result_metadata(MYSQL_STMT *stmt)'

*Description*

If a statement passed to *Note `mysql_stmt_prepare()':
mysql-stmt-prepare. is one that produces a result set, *Note
`mysql_stmt_result_metadata()': mysql-stmt-result-metadata.  returns
the result set metadata in the form of a pointer to a `MYSQL_RES'
structure that can be used to process the meta information such as
total number of fields and individual field information. This result
set pointer can be passed as an argument to any of the field-based API
functions that process result set metadata, such as:

   * *Note `mysql_num_fields()': mysql-num-fields.

   * *Note `mysql_fetch_field()': mysql-fetch-field.

   * *Note `mysql_fetch_field_direct()': mysql-fetch-field-direct.

   * *Note `mysql_fetch_fields()': mysql-fetch-fields.

   * *Note `mysql_field_count()': mysql-field-count.

   * *Note `mysql_field_seek()': mysql-field-seek.

   * *Note `mysql_field_tell()': mysql-field-tell.

   * *Note `mysql_free_result()': mysql-free-result.

The result set structure should be freed when you are done with it,
which you can do by passing it to *Note `mysql_free_result()':
mysql-free-result. This is similar to the way you free a result set
obtained from a call to *Note `mysql_store_result()':
mysql-store-result.

The result set returned by *Note `mysql_stmt_result_metadata()':
mysql-stmt-result-metadata.  contains only metadata. It does not
contain any row results. The rows are obtained by using the statement
handle with *Note `mysql_stmt_fetch()': mysql-stmt-fetch.

*Return Values*

A `MYSQL_RES' result structure.  `NULL' if no meta information exists
for the prepared query.

*Errors*

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

For the usage of *Note `mysql_stmt_result_metadata()':
mysql-stmt-result-metadata, refer to the Example from *Note
mysql-stmt-fetch::.


File: manual.info,  Node: mysql-stmt-row-seek,  Next: mysql-stmt-row-tell,  Prev: mysql-stmt-result-metadata,  Up: c-api-prepared-statement-functions

20.10.7.24 `mysql_stmt_row_seek()'
..................................

`MYSQL_ROW_OFFSET mysql_stmt_row_seek(MYSQL_STMT *stmt,
MYSQL_ROW_OFFSET offset)'

*Description*

Sets the row cursor to an arbitrary row in a statement result set. The
`offset' value is a row offset that should be a value returned from
*Note `mysql_stmt_row_tell()': mysql-stmt-row-tell. or from *Note
`mysql_stmt_row_seek()': mysql-stmt-row-seek. This value is not a row
number; if you want to seek to a row within a result set by number, use
*Note `mysql_stmt_data_seek()': mysql-stmt-data-seek. instead.

This function requires that the result set structure contains the
entire result of the query, so *Note `mysql_stmt_row_seek()':
mysql-stmt-row-seek. may be used only in conjunction with *Note
`mysql_stmt_store_result()': mysql-stmt-store-result.

*Return Values*

The previous value of the row cursor. This value may be passed to a
subsequent call to *Note `mysql_stmt_row_seek()': mysql-stmt-row-seek.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-row-tell,  Next: mysql-stmt-send-long-data,  Prev: mysql-stmt-row-seek,  Up: c-api-prepared-statement-functions

20.10.7.25 `mysql_stmt_row_tell()'
..................................

`MYSQL_ROW_OFFSET mysql_stmt_row_tell(MYSQL_STMT *stmt)'

*Description*

Returns the current position of the row cursor for the last *Note
`mysql_stmt_fetch()': mysql-stmt-fetch. This value can be used as an
argument to *Note `mysql_stmt_row_seek()': mysql-stmt-row-seek.

You should use *Note `mysql_stmt_row_tell()': mysql-stmt-row-tell. only
after *Note `mysql_stmt_store_result()': mysql-stmt-store-result.

*Return Values*

The current offset of the row cursor.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-send-long-data,  Next: mysql-stmt-sqlstate,  Prev: mysql-stmt-row-tell,  Up: c-api-prepared-statement-functions

20.10.7.26 `mysql_stmt_send_long_data()'
........................................

`my_bool mysql_stmt_send_long_data(MYSQL_STMT *stmt, unsigned int
parameter_number, const char *data, unsigned long length)'

*Description*

Allows an application to send parameter data to the server in pieces
(or `chunks'). Call this function after *Note
`mysql_stmt_bind_param()': mysql-stmt-bind-param. and before *Note
`mysql_stmt_execute()': mysql-stmt-execute. It can be called multiple
times to send the parts of a character or binary data value for a
column, which must be one of the *Note `TEXT': blob. or *Note `BLOB':
blob. data types.

`parameter_number' indicates which parameter to associate the data
with. Parameters are numbered beginning with 0. `data' is a pointer to
a buffer containing data to be sent, and `length' indicates the number
of bytes in the buffer.

*Note*:

The next *Note `mysql_stmt_execute()': mysql-stmt-execute.  call
ignores the bind buffer for all parameters that have been used with
*Note `mysql_stmt_send_long_data()': mysql-stmt-send-long-data.  since
last *Note `mysql_stmt_execute()': mysql-stmt-execute. or *Note
`mysql_stmt_reset()': mysql-stmt-reset.

If you want to reset/forget the sent data, you can do it with *Note
`mysql_stmt_reset()': mysql-stmt-reset. See *Note mysql-stmt-reset::.

*Return Values*

Zero if the data is sent successfully to server. Non-zero if an error
occurred.

*Errors*

   * `CR_INVALID_BUFFER_USE'

     The parameter does not have a string or binary type.

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

The following example demonstrates how to send the data for a *Note
`TEXT': blob. column in chunks. It inserts the data value `'MySQL - The
most popular Open Source database'' into the `text_column' column. The
`mysql' variable is assumed to be a valid connection handle.

     #define INSERT_QUERY "INSERT INTO \
                           test_long_data(text_column) VALUES(?)"

     MYSQL_BIND bind[1];
     long       length;

     stmt = mysql_stmt_init(mysql);
     if (!stmt)
     {
       fprintf(stderr, " mysql_stmt_init(), out of memory\n");
       exit(0);
     }
     if (mysql_stmt_prepare(stmt, INSERT_QUERY, strlen(INSERT_QUERY)))
     {
       fprintf(stderr, "\n mysql_stmt_prepare(), INSERT failed");
       fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
       exit(0);
     }
      memset(bind, 0, sizeof(bind));
      bind[0].buffer_type= MYSQL_TYPE_STRING;
      bind[0].length= &length;
      bind[0].is_null= 0;

     /* Bind the buffers */
     if (mysql_stmt_bind_param(stmt, bind))
     {
       fprintf(stderr, "\n param bind failed");
       fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
       exit(0);
     }

      /* Supply data in chunks to server */
      if (mysql_stmt_send_long_data(stmt,0,"MySQL",5))
     {
       fprintf(stderr, "\n send_long_data failed");
       fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
       exit(0);
     }

      /* Supply the next piece of data */
      if (mysql_stmt_send_long_data(stmt,0,
                " - The most popular Open Source database",40))
     {
       fprintf(stderr, "\n send_long_data failed");
       fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
       exit(0);
     }

      /* Now, execute the query */
      if (mysql_stmt_execute(stmt))
     {
       fprintf(stderr, "\n mysql_stmt_execute failed");
       fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
       exit(0);
     }


File: manual.info,  Node: mysql-stmt-sqlstate,  Next: mysql-stmt-store-result,  Prev: mysql-stmt-send-long-data,  Up: c-api-prepared-statement-functions

20.10.7.27 `mysql_stmt_sqlstate()'
..................................

`const char *mysql_stmt_sqlstate(MYSQL_STMT *stmt)'

*Description*

For the statement specified by `stmt', *Note `mysql_stmt_sqlstate()':
mysql-stmt-sqlstate. returns a null-terminated string containing the
SQLSTATE error code for the most recently invoked prepared statement
API function that can succeed or fail. The error code consists of five
characters.  `"00000"' means `no error.' The values are specified by
ANSI SQL and ODBC. For a list of possible values, see *Note
error-handling::.

Note that not all MySQL errors are yet mapped to SQLSTATE codes.  The
value `"HY000"' (general error) is used for unmapped errors.

*Return Values*

A null-terminated character string containing the SQLSTATE error code.


File: manual.info,  Node: mysql-stmt-store-result,  Prev: mysql-stmt-sqlstate,  Up: c-api-prepared-statement-functions

20.10.7.28 `mysql_stmt_store_result()'
......................................

`int mysql_stmt_store_result(MYSQL_STMT *stmt)'

*Description*

Result sets are produced by executing prepared statements for SQL
statements such as *Note `SELECT': select, *Note `SHOW': show, *Note
`DESCRIBE': describe, and *Note `EXPLAIN': explain. By default, result
sets for successfully executed prepared statements are not buffered on
the client and *Note `mysql_stmt_fetch()': mysql-stmt-fetch. fetches
them one at a time from the server. To cause the complete result set to
be buffered on the client, call *Note `mysql_stmt_store_result()':
mysql-stmt-store-result. after binding data buffers with *Note
`mysql_stmt_bind_result()': mysql-stmt-bind-result. and before calling
*Note `mysql_stmt_fetch()': mysql-stmt-fetch. to fetch rows. (For an
example, see *Note mysql-stmt-fetch::.)

*Note `mysql_stmt_store_result()': mysql-stmt-store-result. is optional
for result set processing, unless you will call *Note
`mysql_stmt_data_seek()': mysql-stmt-data-seek, *Note
`mysql_stmt_row_seek()': mysql-stmt-row-seek, or *Note
`mysql_stmt_row_tell()': mysql-stmt-row-tell. Those functions require a
seekable result set.

It is unnecessary to call *Note `mysql_stmt_store_result()':
mysql-stmt-store-result. after executing an SQL statement that does not
produce a result set, but if you do, it does not harm or cause any
notable performance problem. You can detect whether the statement
produced a result set by checking if *Note
`mysql_stmt_result_metadata()': mysql-stmt-result-metadata.  returns
`NULL'. For more information, refer to *Note
mysql-stmt-result-metadata::.

*Note*:

MySQL doesn't by default calculate `MYSQL_FIELD->max_length' for all
columns in *Note `mysql_stmt_store_result()': mysql-stmt-store-result.
because calculating this would slow down *Note
`mysql_stmt_store_result()': mysql-stmt-store-result.  considerably and
most applications don't need `max_length'. If you want `max_length' to
be updated, you can call *Note `mysql_stmt_attr_set(MYSQL_STMT,
STMT_ATTR_UPDATE_MAX_LENGTH, &flag)': mysql-stmt-attr-set. to enable
this. See *Note mysql-stmt-attr-set::.

*Return Values*

Zero if the results are buffered successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: c-thread-functions,  Next: c-embedded-server-functions,  Prev: c-api-prepared-statement-functions,  Up: c

20.10.8 C API Threaded Function Descriptions
--------------------------------------------

* Menu:

* my-init::                      `my_init()'
* mysql-thread-end::             `mysql_thread_end()'
* mysql-thread-init::            `mysql_thread_init()'
* mysql-thread-safe::            `mysql_thread_safe()'

You need to use the following functions when you want to create a
threaded client. See *Note threaded-clients::.


File: manual.info,  Node: my-init,  Next: mysql-thread-end,  Prev: c-thread-functions,  Up: c-thread-functions

20.10.8.1 `my_init()'
.....................

`void my_init(void)'

*Description*

*Note `my_init()': my-init. initializes some global variables that
MySQL needs. If you are using a thread-safe client library, it also
calls *Note `mysql_thread_init()': mysql-thread-init. for this thread.

It is necessary for *Note `my_init()': my-init. to be called early in
the initialization phase of a program's use of the MySQL library.
However, *Note `my_init()': my-init. is automatically called by *Note
`mysql_init()': mysql-init, *Note `mysql_library_init()':
mysql-library-init, *Note `mysql_server_init()': mysql-server-init, and
*Note `mysql_connect()': mysql-connect. If you ensure that your program
invokes one of those functions before any other MySQL calls, there is
no need to invoke *Note `my_init()': my-init. explicitly.

To access the prototype for *Note `my_init()': my-init, your program
should include these header files:

     #include <my_global.h>
     #include <my_sys.h>

*Return Values*

None.


File: manual.info,  Node: mysql-thread-end,  Next: mysql-thread-init,  Prev: my-init,  Up: c-thread-functions

20.10.8.2 `mysql_thread_end()'
..............................

`void mysql_thread_end(void)'

*Description*

This function needs to be called before calling `pthread_exit()' to
free memory allocated by *Note `mysql_thread_init()': mysql-thread-init.

*Note `mysql_thread_end()': mysql-thread-end. _is not invoked
automatically by the client library_. It must be called explicitly to
avoid a memory leak.

*Return Values*

None.


File: manual.info,  Node: mysql-thread-init,  Next: mysql-thread-safe,  Prev: mysql-thread-end,  Up: c-thread-functions

20.10.8.3 `mysql_thread_init()'
...............................

`my_bool mysql_thread_init(void)'

*Description*

This function must be called early within each created thread to
initialize thread-specific variables. However, you may not necessarily
need to invoke it explicitly: *Note `mysql_thread_init()':
mysql-thread-init. is automatically called by *Note `my_init()':
my-init, which itself is automatically called by *Note `mysql_init()':
mysql-init, *Note `mysql_library_init()': mysql-library-init, *Note
`mysql_server_init()': mysql-server-init, and *Note `mysql_connect()':
mysql-connect. If you invoke any of those functions, *Note
`mysql_thread_init()': mysql-thread-init. will be called for you.

*Return Values*

Zero if successful. Non-zero if an error occurred.


File: manual.info,  Node: mysql-thread-safe,  Prev: mysql-thread-init,  Up: c-thread-functions

20.10.8.4 `mysql_thread_safe()'
...............................

`unsigned int mysql_thread_safe(void)'

*Description*

This function indicates whether the client library is compiled as
thread-safe.

*Return Values*

1 if the client library is thread-safe, 0 otherwise.


File: manual.info,  Node: c-embedded-server-functions,  Next: c-api-problems,  Prev: c-thread-functions,  Up: c

20.10.9 C API Embedded Server Function Descriptions
---------------------------------------------------

* Menu:

* mysql-server-init::            `mysql_server_init()'
* mysql-server-end::             `mysql_server_end()'

MySQL applications can be written to use an embedded server. See *Note
libmysqld::. To write such an application, you must link it against the
`libmysqld' library by using the `-lmysqld' flag rather than linking it
against the `libmysqlclient' client library by using the
`-lmysqlclient' flag. However, the calls to initialize and finalize the
library are the same whether you write a client application or one that
uses the embedded server: Call *Note `mysql_library_init()':
mysql-library-init. to initialize the library and *Note
`mysql_library_end()': mysql-library-end. when you are done with it.
See *Note c-api-function-overview::.


File: manual.info,  Node: mysql-server-init,  Next: mysql-server-end,  Prev: c-embedded-server-functions,  Up: c-embedded-server-functions

20.10.9.1 `mysql_server_init()'
...............................

`int mysql_server_init(int argc, char **argv, char **groups)'

*Description*

This function initializes the MySQL library, which must be done before
you call any other MySQL function. However, *Note
`mysql_server_init()': mysql-server-init. is deprecated and you should
call *Note `mysql_library_init()': mysql-library-init. instead.  See
*Note mysql-library-init::.

*Return Values*

Zero if successful. Non-zero if an error occurred.


File: manual.info,  Node: mysql-server-end,  Prev: mysql-server-init,  Up: c-embedded-server-functions

20.10.9.2 `mysql_server_end()'
..............................

`void mysql_server_end(void)'

*Description*

This function finalizes the MySQL library, which should be done when
you are done using the library. However, *Note `mysql_server_end()':
mysql-server-end. is deprecated and *Note `mysql_library_end()':
mysql-library-end. should be used instead. See *Note
mysql-library-end::.

*Return Values*

None.


File: manual.info,  Node: c-api-problems,  Next: auto-reconnect,  Prev: c-embedded-server-functions,  Up: c

20.10.10 Common Questions and Problems When Using the C API
-----------------------------------------------------------

* Menu:

* null-mysql-store-result::      Why `mysql_store_result()' Sometimes Returns `NULL' After `mysql_query()' Returns Success
* query-results::                What Results You Can Get from a Query
* getting-unique-id::            How to Get the Unique ID for the Last Inserted Row
* c-api-linking-problems::       Problems Linking with the C API


File: manual.info,  Node: null-mysql-store-result,  Next: query-results,  Prev: c-api-problems,  Up: c-api-problems

20.10.10.1 Why `mysql_store_result()' Sometimes Returns `NULL' After `mysql_query()' Returns Success
....................................................................................................

It is possible for *Note `mysql_store_result()': mysql-store-result. to
return `NULL' following a successful call to *Note `mysql_query()':
mysql-query. When this happens, it means one of the following
conditions occurred:

   * There was a `malloc()' failure (for example, if the result set was
     too large).

   * The data couldn't be read (an error occurred on the connection).

   * The query returned no data (for example, it was an *Note `INSERT':
     insert, *Note `UPDATE': update, or *Note `DELETE': delete.).

You can always check whether the statement should have produced a
non-empty result by calling *Note `mysql_field_count()':
mysql-field-count. If *Note `mysql_field_count()': mysql-field-count.
returns zero, the result is empty and the last query was a statement
that does not return values (for example, an *Note `INSERT': insert. or
a *Note `DELETE': delete.). If *Note `mysql_field_count()':
mysql-field-count. returns a non-zero value, the statement should have
produced a non-empty result. See the description of the *Note
`mysql_field_count()': mysql-field-count. function for an example.

You can test for an error by calling *Note `mysql_error()':
mysql-error. or *Note `mysql_errno()': mysql-errno.


File: manual.info,  Node: query-results,  Next: getting-unique-id,  Prev: null-mysql-store-result,  Up: c-api-problems

20.10.10.2 What Results You Can Get from a Query
................................................

In addition to the result set returned by a query, you can also get the
following information:

   * *Note `mysql_affected_rows()': mysql-affected-rows.  returns the
     number of rows affected by the last query when doing an *Note
     `INSERT': insert, *Note `UPDATE': update, or *Note `DELETE':
     delete.

     For a fast re-create, use *Note `TRUNCATE TABLE': truncate.

   * *Note `mysql_num_rows()': mysql-num-rows. returns the number of
     rows in a result set. With *Note `mysql_store_result()':
     mysql-store-result, *Note `mysql_num_rows()': mysql-num-rows. may
     be called as soon as *Note `mysql_store_result()':
     mysql-store-result.  returns. With *Note `mysql_use_result()':
     mysql-use-result, *Note `mysql_num_rows()': mysql-num-rows. may be
     called only after you have fetched all the rows with *Note
     `mysql_fetch_row()': mysql-fetch-row.

   * *Note `mysql_insert_id()': mysql-insert-id. returns the ID
     generated by the last query that inserted a row into a table with
     an `AUTO_INCREMENT' index. See *Note mysql-insert-id::.

   * Some queries (`LOAD DATA INFILE ...', `INSERT INTO ... SELECT ...',
     *Note `UPDATE': update.) return additional information. The result
     is returned by *Note `mysql_info()': mysql-info. See the
     description for *Note `mysql_info()': mysql-info.  for the format
     of the string that it returns.  *Note `mysql_info()': mysql-info.
     returns a `NULL' pointer if there is no additional information.


File: manual.info,  Node: getting-unique-id,  Next: c-api-linking-problems,  Prev: query-results,  Up: c-api-problems

20.10.10.3 How to Get the Unique ID for the Last Inserted Row
.............................................................

If you insert a record into a table that contains an `AUTO_INCREMENT'
column, you can obtain the value stored into that column by calling the
*Note `mysql_insert_id()': mysql-insert-id. function.

You can check from your C applications whether a value was stored in an
`AUTO_INCREMENT' column by executing the following code (which assumes
that you've checked that the statement succeeded). It determines
whether the query was an *Note `INSERT': insert. with an
`AUTO_INCREMENT' index:

     if ((result = mysql_store_result(&mysql)) == 0 &&
         mysql_field_count(&mysql) == 0 &&
         mysql_insert_id(&mysql) != 0)
     {
         used_id = mysql_insert_id(&mysql);
     }

When a new `AUTO_INCREMENT' value has been generated, you can also
obtain it by executing a `SELECT LAST_INSERT_ID()' statement with *Note
`mysql_query()': mysql-query. and retrieving the value from the result
set returned by the statement.

When inserting multiple values, the last automatically incremented
value is returned.

For `LAST_INSERT_ID()', the most recently generated ID is maintained in
the server on a per-connection basis. It is not changed by another
client. It is not even changed if you update another `AUTO_INCREMENT'
column with a non-magic value (that is, a value that is not `NULL' and
not `0'). Using `LAST_INSERT_ID()' and `AUTO_INCREMENT' columns
simultaneously from multiple clients is perfectly valid. Each client
will receive the last inserted ID for the last statement _that_ client
executed.

If you want to use the ID that was generated for one table and insert
it into a second table, you can use SQL statements like this:

     INSERT INTO foo (auto,text)
         VALUES(NULL,'text');         # generate ID by inserting NULL
     INSERT INTO foo2 (id,text)
         VALUES(LAST_INSERT_ID(),'text');  # use ID in second table

Note that *Note `mysql_insert_id()': mysql-insert-id.  returns the
value stored into an `AUTO_INCREMENT' column, whether that value is
automatically generated by storing `NULL' or `0' or was specified as an
explicit value.  `LAST_INSERT_ID()' returns only automatically
generated `AUTO_INCREMENT' values. If you store an explicit value other
than `NULL' or `0', it does not affect the value returned by
`LAST_INSERT_ID()'.

For more information on obtaining the last ID in an `AUTO_INCREMENT'
column:

   * For information on `LAST_INSERT_ID()', which can be used within an
     SQL statement, see *Note information-functions::.

   * For information on *Note `mysql_insert_id()': mysql-insert-id, the
     function you use from within the C API, see *Note
     mysql-insert-id::.

   * For information on obtaining the auto-incremented value when using
     Connector/J, see *Note connector-j-usagenotes::.

   * For information on obtaining the auto-incremented value when using
     Connector/ODBC, see *Note
     connector-odbc-usagenotes-functionality-last-insert-id::.


File: manual.info,  Node: c-api-linking-problems,  Prev: getting-unique-id,  Up: c-api-problems

20.10.10.4 Problems Linking with the C API
..........................................

When linking with the C API, the following errors may occur on some
systems:

     gcc -g -o client test.o -L/usr/local/lib/mysql \
                             -lmysqlclient -lsocket -lnsl

     Undefined        first referenced
      symbol          in file
     floor            /usr/local/lib/mysql/libmysqlclient.a(password.o)
     ld: fatal: Symbol referencing errors. No output written to client

If this happens on your system, you must include the math library by
adding `-lm' to the end of the compile/link line.


File: manual.info,  Node: auto-reconnect,  Next: c-api-multiple-queries,  Prev: c-api-problems,  Up: c

20.10.11 Controlling Automatic Reconnection Behavior
----------------------------------------------------

The MySQL client library can perform an automatic reconnection to the
server if it finds that the connection is down when you attempt to send
a statement to the server to be executed. In this case, the library
tries once to reconnect to the server and send the statement again.

If it is important for your application to know that the connection has
been dropped (so that is can exit or take action to adjust for the loss
of state information), be sure to disable auto-reconnect. This can be
done explicitly by calling *Note `mysql_options()': mysql-options. with
the `MYSQL_OPT_RECONNECT' option:

     my_bool reconnect = 0;
     mysql_options(&mysql, MYSQL_OPT_RECONNECT, &reconnect);

In MySQL 6.0, auto-reconnect is disabled by default.

If the connection has gone down, the *Note `mysql_ping()': mysql-ping.
function performs a reconnect if auto-reconnect is enabled. If
auto-reconnect is disabled, *Note `mysql_ping()': mysql-ping. returns an
error instead.

Some client programs might provide the capability of controlling
automatic reconnection. For example, *Note `mysql': mysql.  reconnects
by default, but the `--skip-reconnect' option can be used to suppress
this behavior.

If an automatic reconnection does occur (for example, as a result of
calling *Note `mysql_ping()': mysql-ping.), there is no explicit
indication of it. To check for reconnection, call *Note
`mysql_thread_id()': mysql-thread-id. to get the original connection
identifier before calling *Note `mysql_ping()': mysql-ping, and then
call *Note `mysql_thread_id()': mysql-thread-id. again to see whether
the identifier has changed.

Automatic reconnection can be convenient because you need not implement
your own reconnect code, but if a reconnection does occur, several
aspects of the connection state are reset and your application will not
know about it. The connection-related state is affected as follows:

   * Any active transactions are rolled back and autocommit mode is
     reset.

   * All table locks are released.

   * All `TEMPORARY' tables are closed (and dropped).

   * Session variables are reinitialized to the values of the
     corresponding variables. This also affects variables that are set
     implicitly by statements such as `SET NAMES'.

   * User variable settings are lost.

   * Prepared statements are released.

   * *Note `HANDLER': handler. variables are closed.

   * The value of `LAST_INSERT_ID()' is reset to 0.

   * Locks acquired with `GET_LOCK()' are released.

If the connection drops, it is possible that the session associated
with the connection on the server side will still be running if the
server has not yet detected that the client is no longer connected. In
this case, any locks held by the original connection still belong to
that session, so you may want to kill it by calling *Note
`mysql_kill()': mysql-kill.


File: manual.info,  Node: c-api-multiple-queries,  Next: c-api-prepared-statement-problems,  Prev: auto-reconnect,  Up: c

20.10.12 C API Support for Multiple Statement Execution
-------------------------------------------------------

By default, *Note `mysql_query()': mysql-query. and *Note
`mysql_real_query()': mysql-real-query. interpret their statement
string argument as a single statement to be executed, and you process
the result according to whether the statement produces a result set (a
set of rows, as for *Note `SELECT': select.) or an affected-rows count
(as for *Note `INSERT': insert, *Note `UPDATE': update, and so forth).

MySQL 6.0 also supports the execution of a string containing multiple
statements separated by semicolon (``;'') characters. This capability
is enabled by special options that are specified either when you
connect to the server with *Note `mysql_real_connect()':
mysql-real-connect. or after connecting by calling` *Note
`mysql_set_server_option()': mysql-set-server-option.

Executing a multiple-statement string can produce multiple result sets
or row-count indicators. Processing these results involves a different
approach than for the single-statement case: After handling the result
from the first statement, it is necessary to check whether more results
exist and process them in turn if so.  To support multiple-result
processing, the C API includes the *Note `mysql_more_results()':
mysql-more-results. and *Note `mysql_next_result()': mysql-next-result.
functions.  These functions are used at the end of a loop that iterates
as long as more results are available. _Failure to process the result
this way may result in a dropped connection to the server._

Multiple-result processing also is required if you execute *Note
`CALL': call. statements for stored procedures. Results from a stored
procedure have these characteristics:

   * Statements within the procedure may produce result sets (for
     example, if it executes *Note `SELECT': select.  statements).
     These result sets are returned in the order that they are produced
     as the procedure executes.

     In general, the caller cannot know how many result sets a
     procedure will return. Procedure execution may depend on loops or
     conditional statements that cause the execution path to differ
     from one call to the next. Therefore, you must be prepared to
     retrieve multiple results.

   * The final result from the procedure is a status result that
     includes no result set. The status indicates whether the procedure
     succeeded or an error occurred.

The multiple statement and result capabilities can be used only with
*Note `mysql_query()': mysql-query. or *Note `mysql_real_query()':
mysql-real-query. They cannot be used with the prepared statement
interface. Prepared statement handles are defined to work only with
strings that contain a single statement. See *Note
c-api-prepared-statements::.

To enable multiple-statement execution and result processing, the
following options may be used:

   * The *Note `mysql_real_connect()': mysql-real-connect.  function
     has a `flags' argument for which two option values are relevent:

        * `CLIENT_MULTI_RESULTS' enables the client program to process
          multiple results. This option _must_ be enabled if you execute
          *Note `CALL': call. statements for stored procedures that
          produce result sets. Otherwise, such procedures result in an
          error `Error 1312 (0A000): PROCEDURE PROC_NAME can't return a
          result set in the given context'. As of MySQL 6.0.8,
          `CLIENT_MULTI_RESULTS' is enabled by default.

        * `CLIENT_MULTI_STATEMENTS' enables *Note `mysql_query()':
          mysql-query. and *Note `mysql_real_query()':
          mysql-real-query. to execute statement strings containing
          multiple statements separated by semicolons. This option also
          enables `CLIENT_MULTI_RESULTS' implicitly, so a `flags'
          argument of `CLIENT_MULTI_STATEMENTS' to *Note
          `mysql_real_connect()': mysql-real-connect. is equivalent to
          an argument of `CLIENT_MULTI_STATEMENTS |
          CLIENT_MULTI_RESULTS'. That is, `CLIENT_MULTI_STATEMENTS' is
          sufficient to enable multiple-statement execution and all
          multiple-result processing.

   * After the connection to the server has been established, you can
     use the *Note `mysql_set_server_option()': mysql-set-server-option.
     function to enable or disable multiple-statement execution by
     passing it an argument of `MYSQL_OPTION_MULTI_STATEMENTS_ON' or
     `MYSQL_OPTION_MULTI_STATEMENTS_OFF'. Enabling multiple-statement
     execution with this function also enables processing of `simple'
     results for a multiple-statement string where each statement
     produces a single result, but is _not_ sufficient to allow
     processing of stored procedures that produce result sets.

The following procedure outlines a suggested strategy for handling
multiple statements:

  1. Pass `CLIENT_MULTI_STATEMENTS' to *Note `mysql_real_connect()':
     mysql-real-connect, to fully enable multiple-statement execution
     and multiple-result processing.

  2. After calling *Note `mysql_query()': mysql-query. or *Note
     `mysql_real_query()': mysql-real-query. and verifying that it
     succeeds, enter a loop within which you process statement results.

  3. For each iteration of the loop, handle the current statement
     result, retrieving either a result set or an affected-rows count.
     If an error occurs, exit the loop.

  4. At the end of the loop, call *Note `mysql_next_result()':
     mysql-next-result. to check whether another result exists and
     initiate retrieval for it if so. If no more results are available,
     exit the loop.

One possible implementation of the preceding strategy is shown
following. The final part of the loop can be reduced to a simple test
of whether *Note `mysql_next_result()': mysql-next-result. returns
non-zero. The code as written distinguishes between no more results and
an error, which allows a message to be printed for the latter
occurrence.

     /* connect to server with the CLIENT_MULTI_STATEMENTS option */
     if (mysql_real_connect (mysql, host_name, user_name, password,
         db_name, port_num, socket_name, CLIENT_MULTI_STATEMENTS) == NULL)
     {
       printf("mysql_real_connect() failed\n");
       mysql_close(mysql);
       exit(1);
     }

     /* execute multiple statements */
     status = mysql_query(mysql,
                          "DROP TABLE IF EXISTS test_table;\
                           CREATE TABLE test_table(id INT);\
                           INSERT INTO test_table VALUES(10);\
                           UPDATE test_table SET id=20 WHERE id=10;\
                           SELECT * FROM test_table;\
                           DROP TABLE test_table");
     if (status)
     {
       printf("Could not execute statement(s)");
       mysql_close(mysql);
       exit(0);
     }

     /* process each statement result */
     do {
       /* did current statement return data? */
       result = mysql_store_result(mysql);
       if (result)
       {
         /* yes; process rows and free the result set */
         process_result_set(mysql, result);
         mysql_free_result(result);
       }
       else          /* no result set or error */
       {
         if (mysql_field_count(mysql) == 0)
         {
           printf("%lld rows affected\n",
                 mysql_affected_rows(mysql));
         }
         else  /* some error occurred */
         {
           printf("Could not retrieve result set\n");
           break;
         }
       }
       /* more results? -1 = no, >0 = error, 0 = yes (keep looping) */
       if ((status = mysql_next_result(mysql)) > 0)
         printf("Could not execute statement\n");
     } while (status == 0);

     mysql_close(mysql);


File: manual.info,  Node: c-api-prepared-statement-problems,  Next: c-api-prepared-statement-date-handling,  Prev: c-api-multiple-queries,  Up: c

20.10.13 C API Prepared Statement Problems
------------------------------------------

Here follows a list of the currently known problems with prepared
statements:

   * *Note `TIME': time, *Note `TIMESTAMP': datetime, and *Note
     `DATETIME': datetime. do not support parts of seconds (for
     example, from `DATE_FORMAT()').

   * When converting an integer to string, `ZEROFILL' is honored with
     prepared statements in some cases where the MySQL server doesn't
     print the leading zeros. (For example, with
     `MIN(NUMBER-WITH-ZEROFILL)').

   * When converting a floating-point number to a string in the client,
     the rightmost digits of the converted value may differ slightly
     from those of the original value.

   * Prepared statements use the query cache under the conditions
     described in *Note query-cache-operation::.

   * Prepared statements do not support multi-statements (that is,
     multiple statements within a single string separated by ``;''
     characters).

   * Before MySQL 6.0.8, prepared `CALL' statements cannot invoke
     stored procedures that return result sets because prepared
     statements do not support multiple result sets. Nor can the
     calling application access a stored procedure's `OUT' or `INOUT'
     parameters when the procedure returns. As of MySQL 6.0.8, these
     capabilities are supported as described in *Note
     c-api-prepared-call-statements::.


File: manual.info,  Node: c-api-prepared-statement-date-handling,  Next: c-api-prepared-call-statements,  Prev: c-api-prepared-statement-problems,  Up: c

20.10.14 C API Prepared Statement Handling of Date and Time Values
------------------------------------------------------------------

The binary (prepared statement) protocol allows you to send and receive
date and time values (*Note `DATE': datetime, *Note `TIME': time, *Note
`DATETIME': datetime, and *Note `TIMESTAMP': datetime.), using the
`MYSQL_TIME' structure. The members of this structure are described in
*Note c-api-prepared-statement-datatypes::.

To send temporal data values, create a prepared statement using *Note
`mysql_stmt_prepare()': mysql-stmt-prepare. Then, before calling *Note
`mysql_stmt_execute()': mysql-stmt-execute. to execute the statement,
use the following procedure to set up each temporal parameter:

  1. In the `MYSQL_BIND' structure associated with the data value, set
     the `buffer_type' member to the type that indicates what kind of
     temporal value you're sending. For *Note `DATE': datetime, *Note
     `TIME': time, *Note `DATETIME': datetime, or *Note `TIMESTAMP':
     datetime. values, set `buffer_type' to `MYSQL_TYPE_DATE',
     `MYSQL_TYPE_TIME', `MYSQL_TYPE_DATETIME', or
     `MYSQL_TYPE_TIMESTAMP', respectively.

  2. Set the `buffer' member of the `MYSQL_BIND' structure to the
     address of the `MYSQL_TIME' structure in which you pass the
     temporal value.

  3. Fill in the members of the `MYSQL_TIME' structure that are
     appropriate for the type of temporal value to be passed.

Use *Note `mysql_stmt_bind_param()': mysql-stmt-bind-param. to bind the
parameter data to the statement. Then you can call *Note
`mysql_stmt_execute()': mysql-stmt-execute.

To retrieve temporal values, the procedure is similar, except that you
set the `buffer_type' member to the type of value you expect to
receive, and the `buffer' member to the address of a `MYSQL_TIME'
structure into which the returned value should be placed. Use *Note
`mysql_stmt_bind_result()': mysql-stmt-bind-result. to bind the buffers
to the statement after calling *Note `mysql_stmt_execute()':
mysql-stmt-execute. and before fetching the results.

Here is a simple example that inserts *Note `DATE': datetime, *Note
`TIME': time, and *Note `TIMESTAMP': datetime. data. The `mysql'
variable is assumed to be a valid connection handle.


       MYSQL_TIME  ts;
       MYSQL_BIND  bind[3];
       MYSQL_STMT  *stmt;

       strmov(query, "INSERT INTO test_table(date_field, time_field, \
                                    timestamp_field) VALUES(?,?,?");

       stmt = mysql_stmt_init(mysql);
       if (!stmt)
       {
         fprintf(stderr, " mysql_stmt_init(), out of memory\n");
         exit(0);
       }
       if (mysql_stmt_prepare(mysql, query, strlen(query)))
       {
         fprintf(stderr, "\n mysql_stmt_prepare(), INSERT failed");
         fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
         exit(0);
       }

       /* set up input buffers for all 3 parameters */
       bind[0].buffer_type= MYSQL_TYPE_DATE;
       bind[0].buffer= (char *)&ts;
       bind[0].is_null= 0;
       bind[0].length= 0;
       ...
       bind[1]= bind[2]= bind[0];
       ...

       mysql_stmt_bind_param(stmt, bind);

       /* supply the data to be sent in the ts structure */
       ts.year= 2002;
       ts.month= 02;
       ts.day= 03;

       ts.hour= 10;
       ts.minute= 45;
       ts.second= 20;

       mysql_stmt_execute(stmt);
       ..


File: manual.info,  Node: c-api-prepared-call-statements,  Next: building-clients,  Prev: c-api-prepared-statement-date-handling,  Up: c

20.10.15 C API Support for Prepared `CALL' Statements
-----------------------------------------------------

This section describes prepared-statement support in the C API for
stored procedures executed via *Note `CALL': call.  statements:

Prior to MySQL 6.0.8, prepared *Note `CALL': call.  statements can be
used only for stored procedures that produce at most one result set.
Nor can the calling application use placeholders for `OUT' or `INOUT'
parameters.

MySQL 6.0.8 expands support for stored procedures executed via prepared
*Note `CALL': call. statements in the following ways:

   * A stored procedure can produce any number of result sets. The
     number of columns and the data types of the columns need not be
     the same for all result sets.

   * The final values of `OUT' and `INOUT' parameters are available to
     the calling application after the procedure returns. These
     parameters are returned as an extra single-row result set
     following any result sets produced by the procedure itself.  The
     row contains the values of the `OUT' and `INOUT' parameters in the
     order in which they are declared in the procedure parameter list.

The following discussion shows how to use these capabilities via the C
API for prepared statements. To use prepared *Note `CALL': call.
statements via the *Note `PREPARE': prepare. and *Note `EXECUTE':
execute. statements, see *Note call::.

If an application might be compiled or executed in a context where a
version of MySQL older than 6.0.8 is used, prepared *Note `CALL': call.
capabilities for multiple result sets and `OUT' or `INOUT' parameters
might not be available:

   * For the client side, the application will not compile unless the
     libraries are from MySQL 6.0.8 or higher (the API function and
     symbols introduced in that version will not be present).

   * To verify at runtime that the server is recent enough, a client
     can use this test:

          if (mysql_get_server_version(mysql) < 60008)
          {
            fprintf(stderr,
                    "Server does not support required CALL capabilities\n");
            mysql_close(mysql);
            exit (1);
          }

An application that executes a prepared *Note `CALL': call. statement
should use a loop that fetches a result and then invokes *Note
`mysql_stmt_next_result()': mysql-stmt-next-result. to determine
whether there are more results. The results consist of any result sets
produced by the stored procedure followed by a final status value that
indicates whether the procedure terminated successfully.

If the procedure has `OUT' or `INOUT' parameters, the result set
preceding the final status value contains their values. To determine
whether a result set contains parameter values, test whether the
`SERVER_PS_OUT_PARAMS' bit is set in the `server_status' member of the
`MYSQL' connection handler:

     mysql->server_status & SERVER_PS_OUT_PARAMS

The following example uses a prepared *Note `CALL': call. statement to
execute a stored procedure that produces multiple result sets and that
provides parameter values back to the caller by means of `OUT' and
`INOUT' parameters.  The procedure takes parameters of all three types
(`IN', `OUT', `INOUT'), displays their initial values, assigns new
values, displays the updated values, and returns. The expected return
information from the procedure therefore consists of multiple result
sets and a final status:

   * One result set containing the initial parameter values: `10',
     `NULL', `30'. (The `OUT' parameter is assigned a value by the
     caller, but this assignment is expected to be ineffective: `OUT'
     parameters are seen as `NULL' within a procedure until assigned a
     value within the procedure.)

   * One result set containing the modified parameter values: `100',
     `200', `300'.

   * One result set containing the final `OUT' and `INOUT' parameter
     values: `200', `300'.

   * A final status packet.

The code to execute the procedure:

     MYSQL_STMT *stmt;
     MYSQL_BIND ps_params[3];  /* input parameter buffers */
     int        int_data[3];   /* input parameter values */
     my_bool    is_null[3];    /* input parameter nullability */
     int        status;

     /* set up stored procedure */
     status = mysql_query(mysql, "DROP PROCEDURE IF EXISTS p1");
     test_error(mysql, status);

     status = mysql_query(mysql,
       "CREATE PROCEDURE p1("
       "  IN p_in INT, "
       "  OUT p_out INT, "
       "  INOUT p_inout INT) "
       "BEGIN "
       "  SELECT p_in, p_out, p_inout; "
       "  SET p_in = 100, p_out = 200, p_inout = 300; "
       "  SELECT p_in, p_out, p_inout; "
       "END");
     test_error(mysql, status);

     /* initialize and prepare CALL statement with parameter placeholders */
     stmt = mysql_stmt_init(mysql);
     if (!stmt)
     {
       printf("Could not initialize statement\n");
       exit(1);
     }
     status = mysql_stmt_prepare(stmt, "CALL p1(?, ?, ?)", 16);
     test_stmt_error(stmt, status);

     /* initialize parameters: p_in, p_out, p_inout (all INT) */
     memset(ps_params, 0, sizeof (ps_params));

     ps_params[0].buffer_type = MYSQL_TYPE_LONG;
     ps_params[0].buffer = (char *) &int_data[0];
     ps_params[0].length = 0;
     ps_params[0].is_null = 0;

     ps_params[1].buffer_type = MYSQL_TYPE_LONG;
     ps_params[1].buffer = (char *) &int_data[1];
     ps_params[1].length = 0;
     ps_params[1].is_null = 0;

     ps_params[2].buffer_type = MYSQL_TYPE_LONG;
     ps_params[2].buffer = (char *) &int_data[2];
     ps_params[2].length = 0;
     ps_params[2].is_null = 0;

     /* bind parameters */
     status = mysql_stmt_bind_param(stmt, ps_params);
     test_stmt_error(stmt, status);

     /* assign values to parameters and execute statement */
     int_data[0]= 10;  /* p_in */
     int_data[1]= 20;  /* p_inout */
     int_data[2]= 30;  /* p_inout */

     status = mysql_stmt_execute(stmt);
     test_stmt_error(stmt, status);

     /* process results until there are no more */
     do {
       int i;
       int num_fields;       /* number of columns in result */
       MYSQL_FIELD *fields;  /* for result set metadata */
       MYSQL_BIND *rs_bind;  /* for output buffers */

       /* the column count is > 0 if there is a result set */
       /* 0 if the result is only the final status packet */
       num_fields = mysql_stmt_field_count(stmt);

       if (num_fields > 0)
       {
         /* there is a result set to fetch */
         printf("Number of columns in result: %d\n", (int) num_fields);

         /* what kind of result set is this? */
         printf("Data: ");
         if(mysql->server_status & SERVER_PS_OUT_PARAMS)
           printf("this result set contains OUT/INOUT parameters\n");
         else
           printf("this result set is produced by the procedure\n");

         MYSQL_RES *rs_metadata = mysql_stmt_result_metadata(stmt);
         test_stmt_error(stmt, rs_metadata == NULL);

         fields = mysql_fetch_fields(rs_metadata);

         rs_bind = (MYSQL_BIND *) malloc(sizeof (MYSQL_BIND) * num_fields);
         if (!rs_bind)
         {
           printf("Cannot allocate output buffers\n");
           exit(1);
         }
         memset(rs_bind, 0, sizeof (MYSQL_BIND) * num_fields);

         /* set up and bind result set output buffers */
         for (i = 0; i < num_fields; ++i)
         {
           rs_bind[i].buffer_type = fields[i].type;
           rs_bind[i].is_null = &is_null[i];

           switch (fields[i].type)
           {
             case MYSQL_TYPE_LONG:
               rs_bind[i].buffer = (char *) &(int_data[i]);
               rs_bind[i].buffer_length = sizeof (int_data);
               break;

             default:
               fprintf(stderr, "ERROR: unexpected type: %d.\n", fields[i].type);
               exit(1);
           }
         }

         status = mysql_stmt_bind_result(stmt, rs_bind);
         test_stmt_error(stmt, status);

         /* fetch and display result set rows */
         while (1)
         {
           status = mysql_stmt_fetch(stmt);

           if (status == 1 || status == MYSQL_NO_DATA)
             break;

           for (i = 0; i < num_fields; ++i)
           {
             switch (rs_bind[i].buffer_type)
             {
               case MYSQL_TYPE_LONG:
                 if (*rs_bind[i].is_null)
                   printf(" val[%d] = NULL;", i);
                 else
                   printf(" val[%d] = %ld;",
                          i, (long) *((int *) rs_bind[i].buffer));
                 break;

               default:
                 printf("  unexpected type (%d)\n",
                   rs_bind[i].buffer_type);
             }
           }
           printf("\n");
         }

         mysql_free_result(rs_metadata); /* free metadata */
         free(rs_bind);                  /* free output buffers */
       }
       else
       {
         /* no columns = final status packet */
         printf("End of procedure output\n");
       }

       /* more results? -1 = no, >0 = error, 0 = yes (keep looking) */
       status = mysql_stmt_next_result(stmt);
       if (status > 0)
         test_stmt_error(stmt, status);
     } while (status == 0);

     mysql_stmt_close(stmt);

Execution of the procedure should produce the following output:

     Number of columns in result: 3
     Data: this result set is produced by the procedure
      val[0] = 10; val[1] = NULL; val[2] = 30;
     Number of columns in result: 3
     Data: this result set is produced by the procedure
      val[0] = 100; val[1] = 200; val[2] = 300;
     Number of columns in result: 2
     Data: this result set contains OUT/INOUT parameters
      val[0] = 200; val[1] = 300;
     End of procedure output

The code uses two utility routines, `test_error()' `test_stmt_error()',
to check for errors and terminate after printing diagnostic information
if an error occurred:

     static void test_error(MYSQL *mysql, int status)
     {
       if (status)
       {
         printf("Error: %s (errno: %d)\n",
                mysql_error(mysql), mysql_errno(mysql));
         exit(1);
       }
     }

     static void test_stmt_error(MYSQL_STMT *stmt, int status)
     {
       if (status)
       {
         printf("Error: %s (errno: %d)\n",
                mysql_stmt_error(stmt), mysql_stmt_errno(stmt));
         exit(1);
       }
     }


File: manual.info,  Node: building-clients,  Next: threaded-clients,  Prev: c-api-prepared-call-statements,  Up: c

20.10.16 Building Client Programs
---------------------------------

If you compile MySQL clients that you've written yourself or that you
obtain from a third-party, they must be linked using the `-lmysqlclient
-lz' options in the link command.  You may also need to specify a `-L'
option to tell the linker where to find the library. For example, if
the library is installed in `/usr/local/mysql/lib', use
`-L/usr/local/mysql/lib -lmysqlclient -lz' in the link command.

For clients that use MySQL header files, you may need to specify an
`-I' option when you compile them (for example,
`-I/usr/local/mysql/include'), so that the compiler can find the header
files.

To make it simpler to compile MySQL programs on Unix, we have provided
the *Note `mysql_config': mysql-config. script for you. See *Note
mysql-config::.

You can use it to compile a MySQL client as follows:

     CFG=/usr/local/mysql/bin/mysql_config
     sh -c "gcc -o progname `$CFG --cflags` progname.c `$CFG --libs`"

The `sh -c' is needed to get the shell not to treat the output from
*Note `mysql_config': mysql-config. as one word.


File: manual.info,  Node: threaded-clients,  Prev: building-clients,  Up: c

20.10.17 How to Make a Threaded Client
--------------------------------------

The client library is almost thread-safe. The biggest problem is that
the subroutines in `net.c' that read from sockets are not interrupt
safe. This was done with the thought that you might want to have your
own alarm that can break a long read to a server. If you install
interrupt handlers for the `SIGPIPE' interrupt, the socket handling
should be thread-safe.

To avoid aborting the program when a connection terminates, MySQL
blocks `SIGPIPE' on the first call to *Note `mysql_library_init()':
mysql-library-init, *Note `mysql_init()': mysql-init, or *Note
`mysql_connect()': mysql-connect. If you want to use your own `SIGPIPE'
handler, you should first call *Note `mysql_library_init()':
mysql-library-init. and then install your handler.

Before MySQL 4.0, binary client libraries that we provided other than
those for Windows were not normally compiled with the thread-safe
option. Current binary distributions should have both a normal and a
thread-safe client library.

To create a threaded client where you can interrupt the client from
other threads and set timeouts when talking with the MySQL server, you
should use the `net_serv.o' code that the server uses and the `-lmysys',
`-lmystrings', and `-ldbug' libraries.

If you don't need interrupts or timeouts, you can just compile a
thread-safe client library `(mysqlclient_r)' and use it. In this case,
you don't have to worry about the `net_serv.o' object file or the other
MySQL libraries.

When using a threaded client and you want to use timeouts and
interrupts, you can make great use of the routines in the `thr_alarm.c'
file. If you are using routines from the `mysys' library, the only
thing you must remember is to call *Note `my_init()': my-init.  first!
See *Note c-thread-functions::.

In all cases, be sure to initialize the client library by calling *Note
`mysql_library_init()': mysql-library-init. before calling any other
MySQL functions. When you are done with the library, call *Note
`mysql_library_end()': mysql-library-end.

*Note `mysql_real_connect()': mysql-real-connect. is not thread-safe by
default. The following notes describe how to compile a thread-safe
client library and use it in a thread-safe manner. (The notes below for
*Note `mysql_real_connect()': mysql-real-connect. also apply to the
older *Note `mysql_connect()': mysql-connect. routine as well, although
*Note `mysql_connect()': mysql-connect.  is deprecated and should no
longer be used.)

To make *Note `mysql_real_connect()': mysql-real-connect.  thread-safe,
you must configure your MySQL distribution with this command:

     shell> ./configure --enable-thread-safe-client

Then recompile the distribution to create a thread-safe client library,
`libmysqlclient_r'. (Assuming that your operating system has a
thread-safe `gethostbyname_r()' function.) This library is thread-safe
per connection. You can let two threads share the same connection with
the following caveats:

   * Two threads can't send a query to the MySQL server at the same
     time on the same connection. In particular, you have to ensure
     that between calls to *Note `mysql_query()': mysql-query. and
     *Note `mysql_store_result()': mysql-store-result. no other thread
     is using the same connection.

   * Many threads can access different result sets that are retrieved
     with *Note `mysql_store_result()': mysql-store-result.

   * If you use *Note `mysql_use_result()': mysql-use-result, you must
     ensure that no other thread is using the same connection until the
     result set is closed. However, it really is best for threaded
     clients that share the same connection to use *Note
     `mysql_store_result()': mysql-store-result.

   * If you want to use multiple threads on the same connection, you
     must have a mutex lock around your pair of *Note `mysql_query()':
     mysql-query. and *Note `mysql_store_result()': mysql-store-result.
     calls.  Once *Note `mysql_store_result()': mysql-store-result. is
     ready, the lock can be released and other threads may query the
     same connection.

   * If you use POSIX threads, you can use `pthread_mutex_lock()' and
     `pthread_mutex_unlock()' to establish and release a mutex lock.

You need to know the following if you have a thread that is calling
MySQL functions which did not create the connection to the MySQL
database:

When you call *Note `mysql_init()': mysql-init, MySQL creates a
thread-specific variable for the thread that is used by the debug
library (among other things). If you call a MySQL function before the
thread has called *Note `mysql_init()': mysql-init, the thread does not
have the necessary thread-specific variables in place and you are
likely to end up with a core dump sooner or later. To get things to
work smoothly you must do the following:

  1. Call *Note `mysql_library_init()': mysql-library-init.  before any
     other MySQL functions. It is not thread-safe, so call it before
     threads are created, or protect the call with a mutex.

  2. Arrange for *Note `mysql_thread_init()': mysql-thread-init. to be
     called early in the thread handler before calling any MySQL
     function. If you call *Note `mysql_init()': mysql-init, they will
     call *Note `mysql_thread_init()': mysql-thread-init. for you.

  3. In the thread, call *Note `mysql_thread_end()': mysql-thread-end.
     before calling `pthread_exit()'. This frees the memory used by
     MySQL thread-specific variables.

The preceding notes regarding *Note `mysql_init()': mysql-init. also
apply to *Note `mysql_connect()': mysql-connect, which calls *Note
`mysql_init()': mysql-init.

If `undefined symbol' errors occur when linking your client with
`libmysqlclient_r', in most cases this is because you haven't included
the thread libraries on the link/compile command.


File: manual.info,  Node: apis-php,  Next: apis-perl,  Prev: c,  Up: connectors-apis

20.11 MySQL PHP API
===================

* Menu:

* connector-php::                Connector/PHP
* apis-php-problems::            Common Problems with MySQL and PHP
* php-mysql-mysqli::             Enabling Both `mysql' and `mysqli' in PHP

PHP is a server-side, HTML-embedded scripting language that may be used
to create dynamic Web pages. It is available for most operating systems
and Web servers, and can access most common databases, including MySQL.
PHP may be run as a separate program or compiled as a module for use
with the Apache Web server.

PHP actually provides two different MySQL API extensions:

   * `mysql': Available for PHP versions 4 and 5, this extension is
     intended for use with MySQL versions prior to MySQL 4.1. This
     extension does not support the improved authentication protocol
     used in MySQL 4.1, nor does it support prepared statements or
     multiple statements. If you wish to use this extension with MySQL
     4.1, you will likely want to configure the MySQL server to use the
     `--old-passwords' option (see *Note old-client::). This extension
     is documented on the PHP Web site at `http://php.net/mysql'.

   * See section "apis-php-mysqli" in the online manual - Stands for
     `MySQL, Improved'; this extension is available only in PHP 5. It
     is intended for use with MySQL 4.1.1 and later. This extension
     fully supports the authentication protocol used in MySQL 5.0, as
     well as the Prepared Statements and Multiple Statements APIs. In
     addition, this extension provides an advanced, object-oriented
     programming interface. You can read the documentation for the
     `mysqli' extension at `http://php.net/mysqli'. Helpful article can
     be found at `http://devzone.zend.com/node/view/id/686' and
     `http://devzone.zend.com/node/view/id/687'.

If you're experiencing problems with enabling both the `mysql' and the
`mysqli' extension when building PHP on Linux yourself, see *Note
php-mysql-mysqli::.

The PHP distribution and documentation are available from the PHP Web
site (http://www.php.net/).

MySQL Enterprise

MySQL Enterprise subscribers will find more information about MySQL and
PHP in the Knowledge Base articles found at PHP
(https://kb.mysql.com/search.php?cat=search&category=23). Access to the
MySQL Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/knowledgebase.html'.

_Portions of this section are Copyright (c) 1997-2008 the PHP
Documentation Group_ This material may be distributed only subject to
the terms and conditions set forth in the Creative Commons Attribution
3.0 License or later. A copy of the Creative Commons Attribution 3.0
license is distributed with this manual. The latest version is
presently available at This material may be distributed only subject to
the terms and conditio\ ns set forth in the Open Publication License,
v1.0.8 or later (the latest version is presently available at
http://www.opencontent.org/openpub/
(http://www.opencontent.org/openpub/)).


File: manual.info,  Node: connector-php,  Next: apis-php-problems,  Prev: apis-php,  Up: apis-php

20.11.1 Connector/PHP
---------------------

The MySQL Connector/PHP is a version of the `mysql' and `mysqli'
extensions for PHP optimized for the Windows operating system. Later
versions of the main PHP `mysql'/`mysqli' drivers are compatible with
Windows and a separate, Windows specific driver is no longer required.

For PHP for all platforms, including Windows, you should use the
`mysql' or `mysqli' extensions shipped with the PHP sources. See *Note
apis-php::.


File: manual.info,  Node: apis-php-problems,  Next: php-mysql-mysqli,  Prev: connector-php,  Up: apis-php

20.11.2 Common Problems with MySQL and PHP
------------------------------------------

   * `Error: Maximum Execution Time Exceeded': This is a PHP limit; go
     into the `php.ini' file and set the maximum execution time up from
     30 seconds to something higher, as needed. It is also not a bad
     idea to double the RAM allowed per script to 16MB instead of 8MB.

   * `Fatal error: Call to unsupported or undefined function
     mysql_connect() in ...': This means that your PHP version isn't
     compiled with MySQL support. You can either compile a dynamic
     MySQL module and load it into PHP or recompile PHP with built-in
     MySQL support. This process is described in detail in the PHP
     manual.

   * `Error: Undefined reference to 'uncompress'': This means that the
     client library is compiled with support for a compressed
     client/server protocol. The fix is to add `-lz' last when linking
     with `-lmysqlclient'.

   * `Error: Client does not support authentication protocol': This is
     most often encountered when trying to use the older `mysql'
     extension with MySQL 4.1.1 and later. Possible solutions are:
     downgrade to MySQL 4.0; switch to PHP 5 and the newer `mysqli'
     extension; or configure the MySQL server with `--old-passwords'.
     (See *Note old-client::, for more information.)

Those with PHP4 legacy code can make use of a compatibility layer for
the old and new MySQL libraries, such as this one:
`http://www.coggeshall.org/oss/mysql2i'.


File: manual.info,  Node: php-mysql-mysqli,  Prev: apis-php-problems,  Up: apis-php

20.11.3 Enabling Both `mysql' and `mysqli' in PHP
-------------------------------------------------

If you're experiencing problems with enabling both the `mysql' and the
`mysqli' extension when building PHP on Linux yourself, you should try
the following procedure.

  1. Configure PHP like this:

          ./configure --with-mysqli=/usr/bin/mysql_config --with-mysql=/usr

  2. Edit the `Makefile' and search for a line that starts with
     `EXTRA_LIBS'. It might look like this (all on one line):

          EXTRA_LIBS = -lcrypt -lcrypt -lmysqlclient -lz -lresolv -lm -ldl -lnsl
          -lxml2 -lz -lm -lxml2 -lz -lm -lmysqlclient -lz -lcrypt -lnsl -lm
          -lxml2 -lz -lm -lcrypt -lxml2 -lz -lm -lcrypt

     Remove all duplicates, so that the line looks like this (all on
     one line):

          EXTRA_LIBS = -lcrypt -lcrypt -lmysqlclient -lz -lresolv -lm -ldl -lnsl
          -lxml2

  3. Build and install PHP:

          make
          make install

MySQL Enterprise

MySQL Enterprise subscribers will find more information about the
mysqli extension in the Knowledge Base articles found at mysqli
(https://kb.mysql.com/search.php?cat=search&cat=search&keywords=mysqli&go=Go).
Access to the MySQL Knowledge Base collection of articles is one of the
advantages of subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: apis-perl,  Next: apis-cplusplus,  Prev: apis-php,  Up: connectors-apis

20.12 MySQL Perl API
====================

The Perl `DBI' module provides a generic interface for database access.
You can write a DBI script that works with many different database
engines without change. To use DBI, you must install the `DBI' module,
as well as a DataBase Driver (DBD) module for each type of server you
want to access. For MySQL, this driver is the `DBD::mysql' module.

Perl DBI is the recommended Perl interface. It replaces an older
interface called `mysqlperl', which should be considered obsolete.

Installation instructions for Perl DBI support are given in *Note
perl-support::.

DBI information is available at the command line, online, or in printed
form:

   * Once you have the `DBI' and `DBD::mysql' modules installed, you
     can get information about them at the command line with the
     `perldoc' command:

          shell> perldoc DBI
          shell> perldoc DBI::FAQ
          shell> perldoc DBD::mysql

     You can also use `pod2man', `pod2html', and so forth to translate
     this information into other formats.

   * For online information about Perl DBI, visit the DBI Web site,
     `http://dbi.perl.org/'. That site hosts a general DBI mailing
     list. Sun Microsystems, Inc. hosts a list specifically about
     `DBD::mysql'; see *Note mailing-lists::.

   * For printed information, the official DBI book is `Programming the
     Perl DBI' (Alligator Descartes and Tim Bunce, O'Reilly &
     Associates, 2000).  Information about the book is available at the
     DBI Web site, `http://dbi.perl.org/'.

     For information that focuses specifically on using DBI with MySQL,
     see `MySQL and Perl for the Web' (Paul DuBois, New Riders, 2001).
     This book's Web site is `http://www.kitebird.com/mysql-perl/'.


File: manual.info,  Node: apis-cplusplus,  Next: apis-python,  Prev: apis-perl,  Up: connectors-apis

20.13 MySQL C++ API
===================

`MySQL++' is a MySQL API for C++. Warren Young has taken over this
project. More information can be found at
`http://tangentsoft.net/mysql++/doc'.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about using C++
with the MySQL API in the MySQL Knowledge Base. articles found at C++
(https://kb.mysql.com/search.php?cat=search&pagerRow=0&category=18).
Access to the MySQL Knowledge Base collection of articles is one of the
advantages of subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: apis-python,  Next: apis-ruby,  Prev: apis-cplusplus,  Up: connectors-apis

20.14 MySQL Python API
======================

`MySQLdb' provides MySQL support for Python, compliant with the Python
DB API version 2.0. It can be found at
`http://sourceforge.net/projects/mysql-python/'.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about using
Python with the MySQL API in the MySQL Knowledge Base articles found at
Python (https://kb.mysql.com/search.php?cat=search&category=24). Access
to the MySQL Knowledge Base collection of articles is one of the
advantages of subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: apis-ruby,  Next: apis-tcl,  Prev: apis-python,  Up: connectors-apis

20.15 MySQL Ruby APIs
=====================

* Menu:

* apis-ruby-mysqlruby::          The MySQL/Ruby API
* apis-ruby-rubymysql::          The Ruby/MySQL API

Two APIs available for Ruby programmers. The MySQL/Ruby API is based on
the `libmysql' API library. The Ruby/MySQL API is written to use the
native MySQL network protocol (a native driver).

For more information on Ruby, see Ruby Programming Language
(http://www.ruby-lang.org).

For information on installing and using the MySQL/Ruby API, see *Note
apis-ruby-mysqlruby::.

For information on installing and using the Ruby/MySQL API, see *Note
apis-ruby-rubymysql::.


File: manual.info,  Node: apis-ruby-mysqlruby,  Next: apis-ruby-rubymysql,  Prev: apis-ruby,  Up: apis-ruby

20.15.1 The MySQL/Ruby API
--------------------------

The MySQL/Ruby module provides access to MySQL databases using Ruby
through `libmysql'.

For information on installing the module, and the functions exposed, see
MySQL/Ruby (http://tmtm.org/en/mysql/ruby/).


File: manual.info,  Node: apis-ruby-rubymysql,  Prev: apis-ruby-mysqlruby,  Up: apis-ruby

20.15.2 The Ruby/MySQL API
--------------------------

The Ruby/MySQL module provides access to MySQL databases using Ruby
through a native driver interface using the MySQL network protocol.

For information on installing the module, and the functions exposed, see
Ruby/MySQL (http://tmtm.org/en/ruby/mysql/README_en.html).


File: manual.info,  Node: apis-tcl,  Next: apis-eiffel,  Prev: apis-ruby,  Up: connectors-apis

20.16 MySQL Tcl API
===================

`MySQLtcl' is a simple API for accessing a MySQL database server from
the Tcl programming language. It can be found at
`http://www.xdobry.de/mysqltcl/'.


File: manual.info,  Node: apis-eiffel,  Prev: apis-tcl,  Up: connectors-apis

20.17 MySQL Eiffel Wrapper
==========================

Eiffel MySQL is an interface to the MySQL database server using the
Eiffel programming language, written by Michael Ravits. It can be found
at `http://efsa.sourceforge.net/archive/ravits/mysql.htm'.


File: manual.info,  Node: extending-mysql,  Next: faqs,  Prev: connectors-apis,  Up: Top

21 Extending MySQL
******************

* Menu:

* mysql-internals::              MySQL Internals
* plugin-api::                   The MySQL Plugin Interface
* adding-functions::             Adding New Functions to MySQL
* adding-procedures::            Adding New Procedures to MySQL
* porting::                      Debugging and Porting MySQL


File: manual.info,  Node: mysql-internals,  Next: plugin-api,  Prev: extending-mysql,  Up: extending-mysql

21.1 MySQL Internals
====================

* Menu:

* mysql-threads::                MySQL Threads
* mysql-test-suite::             MySQL Test Suite

This chapter describes a lot of things that you need to know when
working on the MySQL code. If you plan to contribute to MySQL
development, want to have access to the bleeding-edge versions of the
code, or just want to keep track of development, follow the
instructions in *Note installing-source-tree::. If you are interested
in MySQL internals, you should also subscribe to our `internals'
mailing list. This list has relatively low traffic. For details on how
to subscribe, please see *Note mailing-lists::. All developers at MySQL
AB are on the `internals' list and we help other people who are working
on the MySQL code. Feel free to use this list both to ask questions
about the code and to send patches that you would like to contribute to
the MySQL project!


File: manual.info,  Node: mysql-threads,  Next: mysql-test-suite,  Prev: mysql-internals,  Up: mysql-internals

21.1.1 MySQL Threads
--------------------

The MySQL server creates the following threads:

   * Connection manager threads handle client connection requests on
     the network interfaces that the server listens to. On all
     platforms, one manager thread handles TCP/IP connection requests.
     On Unix, this manager thread also handles Unix socket file
     connection requests. On Windows, a manager thread handles
     shared-memory connection requests, and another handles named-pipe
     connection requests. The server does not create threads to handle
     interfaces that it does not listen to. For example, a Windows
     server that does not have support for named-pipe connections
     enabled does not create a thread to handle them.

   * The original thread model for handing client connections is that
     connection manager threads associate each client connection with a
     thread dedicated to it that handles authentication and request
     processing for that connection.  Manager threads create a new
     thread when necessary but try to avoid doing so by consulting the
     thread cache first to see whether it contains a thread that can be
     used for the connection. When a connection ends, its thread is
     returned to the thread cache if the cache is not full.

     As of MySQL 6.0.4, an alternative thread model is available for
     dealing with the preceding issues that occur when scaling to large
     numbers of simultaneous connections. This model uses thread
     pooling:

        * Connection manager threads do not dedicate a thread to each
          client connection. Instead, the connection is added to the
          set of existing connection sockets. The server collects input
          from these sockets and when a complete request has been
          received from a given client, it is queued for service.

        * The server maintains a pool of service threads to process
          requests. When a queued request is waiting and there is an
          available (not busy) service thread in the pool, the request
          is given to the thread to be handled.  After processing the
          request, the service thread becomes available to process
          other requests.

          Service threads are created at server startup and exist until
          the server terminates. A given service thread is not tied to
          a specific client connection and the requests that it
          processes over time may originate from different client
          connections.

     For information about choosing one thread model over the other and
     tuning the parameters that control thread resources, see *Note
     connection-threads::.

   * On a master replication server, connections from slave servers are
     handled like client connections, using whichever thread model
     applies to the latter.

   * On a slave replication server, an I/O thread is started to connect
     to the master server and read updates from it. An SQL thread is
     started to apply updates read from the master.  These two threads
     run independently and can be started and stopped independently.

   * A signal thread handles all signals. This thread also normally
     handles alarms and calls `process_alarm()' to force timeouts on
     connections that have been idle too long.

   * If `InnoDB' is used, there will be 4 additional threads by
     default. Those are file I/O threads, controlled by the
     `innodb_file_io_threads' parameter. See *Note innodb-parameters::.

   * If *Note `mysqld': mysqld. is compiled with `-DUSE_ALARM_THREAD',
     a dedicated thread that handles alarms is created. This is only
     used on some systems where there are problems with `sigwait()' or
     if you want to use the `thr_alarm()' code in your application
     without a dedicated signal handling thread.

   * If the server is started with the `--flush_time=VAL' option, a
     dedicated thread is created to flush all tables every VAL seconds.

   * Each table for which *Note `INSERT DELAYED': insert-delayed.
     statements are issued gets its own thread.  See *Note
     insert-delayed::.

   * If the event scheduler is active, there is one thread for the
     scheduler, and a thread for each event currently running. See
     *Note events-overview::.

*Note `mysqladmin processlist': mysqladmin. only shows the connection,
*Note `INSERT DELAYED': insert-delayed, replication, and event threads.

MySQL Enterprise

For expert advice on thread management subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: mysql-test-suite,  Prev: mysql-threads,  Up: mysql-internals

21.1.2 MySQL Test Suite
-----------------------

The test system that is included in Unix source and binary
distributions makes it possible for users and developers to perform
regression tests on the MySQL code. These tests can be run on Unix.

You can also write your own test cases. For information about the MySQL
Test Framework, including system requirements, see the manual available
at `http://dev.mysql.com/doc/'.

The current set of test cases doesn't test everything in MySQL, but it
should catch most obvious bugs in the SQL processing code, operating
system or library issues, and is quite thorough in testing replication.
Our goal is to have the tests cover 100% of the code. We welcome
contributions to our test suite. You may especially want to contribute
tests that examine the functionality critical to your system because
this ensures that all future MySQL releases work well with your
applications.

The test system consists of a test language interpreter (`mysqltest'),
a Perl script to run all tests (`mysql-test-run.pl'), the actual test
cases written in a special test language, and their expected results.
To run the test suite on your system after a build, type `make test'
from the source root directory, or change location to the `mysql-test'
directory and type `./mysql-test-run.pl'. If you have installed a
binary distribution, change location to the `mysql-test' directory
under the installation root directory (for example,
`/usr/local/mysql/mysql-test'), and run `./mysql-test-run.pl'. All
tests should succeed. If any do not, feel free to try to find out why
and report the problem if it indicates a bug in MySQL. See *Note
bug-reports::.

If one test fails, you should run `mysql-test-run.pl' with the
`--force' option to check whether any other tests fail.

If you have a copy of *Note `mysqld': mysqld. running on the machine
where you want to run the test suite, you do not have to stop it, as
long as it is not using ports `9306' or `9307'. If either of those
ports is taken, you should set the `MTR_BUILD_THREAD' environment
variable to an appropriate value, and the test suite will use a
different set of ports for master, slave, and NDB). For example:

     shell> export MTR_BUILD_THREAD=31
     shell> ./mysql-test-run.pl [OPTIONS] [TEST_NAME]

In the `mysql-test' directory, you can run an individual test case with
`./mysql-test-run.pl TEST_NAME'.

If you have a question about the test suite, or have a test case to
contribute, send an email message to the MySQL `internals' mailing
list. See *Note mailing-lists::. This list does not accept attachments,
so you should FTP all the relevant files to:
`ftp://ftp.mysql.com/pub/mysql/upload/'


File: manual.info,  Node: plugin-api,  Next: adding-functions,  Prev: mysql-internals,  Up: extending-mysql

21.2 The MySQL Plugin Interface
===============================

* Menu:

* plugin-api-characteristics::   Characteristics of the Plugin Interface
* plugin-full-text-plugins::     Full-Text Parser Plugins
* plugin-writing::               Writing Plugins

MySQL 5.1 and up supports a plugin API that allows the loading and
unloading of server components at runtime, without restarting the
server. The components supported by this operation include, but are not
limited to, full-text parser plugins, storage-engines and server
extensions. In MySQL 6.0, all of the storage engines can built as
plugins, and fulltext examples and partitioning can also be included as
plugins.

Full-text parser plugins can be used to replace or augment the built-in
full-text parser. For example, a plugin can parse text into words using
rules that differ from those used by the built-in parser. This can be
useful if you need to parse text with characteristics different from
those expected by the built-in parser.

The plugin interface is intended as the successor to the older
user-defined function (UDF) interface. The plugin interface eventually
will include an API for creating UDFs, and it is intended this plugin
UDF API will replace the older non-plugin UDF API. After that point, it
will be possible for UDFs to be revised for use as plugin UDFs so that
they can take advantage of the better security and versioning
capabilities of the plugin API.  Eventually, support for the older UDF
API will be phased out.

The plugin interface requires the `plugin' table in the `mysql'
database. This table is created as part of the MySQL installation
process. If you are upgrading from an older version to MySQL 5.1, you
should run the *Note `mysql_upgrade': mysql-upgrade. command to create
this table. See *Note mysql-upgrade::.

For more information on the Plugin API and how it can be used with
storage engines, see MySQL Internals: Custom Engine
(http://forge.mysql.com/wiki/MySQL_Internals_Custom_Engine).


File: manual.info,  Node: plugin-api-characteristics,  Next: plugin-full-text-plugins,  Prev: plugin-api,  Up: plugin-api

21.2.1 Characteristics of the Plugin Interface
----------------------------------------------

In some respects, the plugin API is similar to the older user-defined
function (UDF) API that it supersedes, but the plugin API has several
advantages over the older interface:

   * The plugin framework is extendable to accommodate different kinds
     of plugins.

     Some aspects of the plugin API are common to all types of plugins,
     but the API also allows for type-specific interface elements so
     that different types of plugins can be created.  A plugin with one
     purpose can have an interface most appropriate to its own
     requirements and not the requirements of some other plugin type.

     Although only the interface for full-text parser plugins is
     implemented currently, others can be added, such as an interface
     for UDF plugins.

   * The plugin API includes versioning information.

     The version information included in the plugin API enables a
     plugin library and each plugin that it contains to be
     self-identifying with respect to the API version that was used to
     build the library. If the API changes over time, the version
     numbers will change, but a server can examine a given plugin
     library's version information to determine whether it supports the
     plugins in the library.

     There are two types of version numbers. The first is the version
     for the general plugin framework itself. Each plugin library
     includes this kind of version number. The second type of version
     applies to individual plugins. Each specific type of plugin has a
     version for its interface, so each plugin in a library has a
     type-specific version number. For example, library containing a
     full-text parsing plugin has a general plugin API version number,
     and the plugin has a version number specific to the full-text
     plugin interface.

   * Plugin security is improved relative to the UDF interface.

     The older interface for writing non-plugin UDFs allowed libraries
     to be loaded from any directory searched by the system's dynamic
     linker, and the symbols that identified the UDF library were
     relatively non-specific. The newer rules are more strict. A plugin
     library must be installed in a specific dedicated directory for
     which the location is controlled by the server and cannot be
     changed at runtime.  Also, the library must contain specific
     symbols that identify it as a plugin library. The server will not
     load something as a plugin if it was not built as a plugin.

     The newer plugin interface eliminates the security issues of the
     older UDF interface. When a UDF plugin type is implemented, that
     will allow non-plugin UDFs to be brought into the plugin framework
     and the older interface to be phased out.

The plugin implementation includes the following components:

Source files (the locations given indicate where the files are found in
a MySQL source distribution):

   * `include/mysql/plugin.h' exposes the public plugin API. This file
     should be examined by anyone who wants to write a plugin library.

   * `sql/sql_plugin.h' and `sql/sql_plugin.cc' comprise the internal
     plugin implementation. These files need not be consulted by plugin
     writers. They may be of interest for those who want to know more
     about how the server handles plugins.

System table:

   * The `plugin' table in the `mysql' database lists each installed
     plugin and is required for plugin use. For new MySQL
     installations, this table is created during the installation
     process. If you are upgrading from a version older than MySQL 5.1,
     you should run *Note `mysql_upgrade': mysql-upgrade.  to update
     your system tables and create the `plugin' table (see *Note
     mysql-upgrade::).

SQL statements:

   * *Note `INSTALL PLUGIN': install-plugin. registers a plugin in the
     `plugin' table and loads the plugin code.

   * *Note `UNINSTALL PLUGIN': uninstall-plugin. unregisters a plugin
     from the `plugin' table and unloads the plugin code.

   * The `WITH PARSER' clause for full-text index creation associates a
     full-text parser plugin with a given `FULLTEXT' index.

   * *Note `SHOW PLUGINS': show-plugins. displays information about
     known plugins. The *Note `PLUGINS': plugins-table. table in
     `INFORMATION_SCHEMA' also contains plugin information.

System variable:

   * `plugin_dir' indicates the location of the directory where all
     plugins must be installed. The value of this variable can be
     specified at server startup with a `--plugin_dir=PATH' option. As
     of MySQL 6.0.5, *Note `mysql_config --plugindir': mysql-config.
     displays the default plugin directory path name.


File: manual.info,  Node: plugin-full-text-plugins,  Next: plugin-writing,  Prev: plugin-api-characteristics,  Up: plugin-api

21.2.2 Full-Text Parser Plugins
-------------------------------

MySQL has a built-in parser that it uses by default for full-text
operations (parsing text to be indexed, or parsing a query string to
determine the terms to be used for a search).  For full-text
processing, `parsing' means extracting words from text or a query
string based on rules that define which character sequences make up a
word and where word boundaries lie.

When parsing for indexing purposes, the parser passes each word to the
server, which adds it to a full-text index. When parsing a query
string, the parser passes each word to the server, which accumulates
the words for use in a search.

The parsing properties of the built-in full-text parser are described
in *Note fulltext-search::. These properties include rules for
determining how to extract words from text.  The parser is influenced
by certain system variables such as `ft_min_word_len' and
`ft_max_word_len' that cause words shorter or longer to be excluded,
and by the stopword list that identifies common words to be ignored.

The plugin API enables you to provide a full-text parser of your own so
that you have control over the basic duties of a parser.  A parser
plugin can operate in either of two roles:

   * The plugin can replace the built-in parser. In this role, the
     plugin reads the input to be parsed, splits it up into words, and
     passes the words to the server (either for indexing or for word
     accumulation).

     One reason to use a parser this way is that you need to use
     different rules from those of the built-in parser for determining
     how to split up input into words. For example, the built-in parser
     considers the text `case-sensitive' to consist of two words `case'
     and `sensitive,' whereas an application might need to treat the
     text as a single word.

   * The plugin can act in conjunction with the built-in parser by
     serving as a front end for it. In this role, the plugin extracts
     text from the input and passes the text to the parser, which
     splits up the text into words using its normal parsing rules. In
     particular, this parsing will be affected by the `ft_XXX' system
     variables and the stopword list.

     One reason to use a parser this way is that you need to index
     content such as PDF documents, XML documents, or `.doc' files. The
     built-in parser is not intended for those types of input but a
     plugin can pull out the text from these input sources and pass it
     to the built-in parser.

It is also possible for a parser plugin to operate in both roles. That
is, it could extract text from non-plaintext input (the front end
role), and also parse the text into words (thus replacing the built-in
parser).

A full-text plugin is associated with full-text indexes on a per-index
basis. That is, when you install a parser plugin initially, that does
not cause it to be used for any full-text operations. It simply becomes
available. For example, a full-text parser plugin becomes available to
be named in a `WITH PARSER' clause when creating individual `FULLTEXT'
indexes. To create such an index at table-creation time, do this:

     CREATE TABLE t
     (
       doc CHAR(255),
       FULLTEXT INDEX (doc) WITH PARSER my_parser
     );

Or you can add the index after the table has been created:

     ALTER TABLE t ADD FULLTEXT INDEX (doc) WITH PARSER my_parser;

The only SQL change for associating the parser with the index is the
`WITH PARSER' clause. Searches are specified as before, with no changes
needed for queries.

When you associate a parser plugin with a `FULLTEXT' index, the plugin
is required for using the index. If the parser plugin is dropped, any
index associated with it becomes unusable. Any attempt to use it a
table for which a plugin is not available results in an error, although
*Note `DROP TABLE': drop-table. is still possible.


File: manual.info,  Node: plugin-writing,  Prev: plugin-full-text-plugins,  Up: plugin-api

21.2.3 Writing Plugins
----------------------

* Menu:

* plugin-api-general::           General Plugin Structures and Functions
* plugin-api-type-specific::     Type-Specific Plugin Structures and Functions
* plugin-creating::              Creating a Plugin Library

This section describes the general and type-specific parts of the
plugin API. It also provides a step-by-step guide to creating a plugin
library. For example plugin source code, see the `plugin/fulltext'
directory of a MySQL source distribution.

You can write plugins in C or C++ (or another language that can use C
calling conventions). Plugins are loaded and unloaded dynamically, so
your operating system must support dynamic loading and you must have
compiled *Note `mysqld': mysqld.  dynamically (not statically).

A plugin contains code that becomes part of the running server, so when
you write a plugin, you are bound by any and all constraints that
otherwise apply to writing server code. For example, you may have
problems if you attempt to use functions from the `libstdc++' library.
These constraints may change in future versions of the server, so it is
possible that server upgrades will require revisions to plugins that
were originally written for older servers. For information about these
constraints, see *Note configure-options::, and *Note
compilation-problems::.


File: manual.info,  Node: plugin-api-general,  Next: plugin-api-type-specific,  Prev: plugin-writing,  Up: plugin-writing

21.2.3.1 General Plugin Structures and Functions
................................................

Every plugin must have a general plugin declaration. The declaration
corresponds to the `st_mysql_plugin' structure in the `plugin.h' file:

     struct st_mysql_plugin
     {
       int type;             /* the plugin type (a MYSQL_XXX_PLUGIN value)   */
       void *info;           /* pointer to type-specific plugin descriptor   */
       const char *name;     /* plugin name                                  */
       const char *author;   /* plugin author (for SHOW PLUGINS)             */
       const char *descr;    /* general descriptive text (for SHOW PLUGINS ) */
       int license;          /* the plugin license (PLUGIN_LICENSE_XXX)      */
       int (*init)(void *);  /* the function to invoke when plugin is loaded */
       int (*deinit)(void *);/* the function to invoke when plugin is unloaded */
       unsigned int version; /* plugin version (for SHOW PLUGINS)            */
       struct st_mysql_show_var *status_vars;
       void * __reserved1;   /* placeholder for system variables             */
       void * __reserved2;   /* placeholder for config options               */
     };

The `st_mysql_plugin' structure is common to every type of plugin. Its
members should be filled in as follows:

   * `type'

     The plugin type. This must be one of the plugin-type values from
     `plugin.h'. For a full-text parser plugin, the `type' value is
     `MYSQL_FTPARSER_PLUGIN'.

   * `info'

     A pointer to the descriptor for the plugin. Unlike the general
     plugin declaration structure, this descriptor's structure depends
     on the particular type of plugin. Each descriptor has a version
     number that indicates the API version for that type of plugin,
     plus any other members needed. The descriptor for full-text
     plugins is described in *Note plugin-api-type-specific::.

   * `name'

     The plugin name. This is the name that will be listed in the
     `plugin' table and by which you refer to the plugin in SQL
     statements such as *Note `INSTALL PLUGIN': install-plugin. and
     *Note `UNINSTALL PLUGIN': uninstall-plugin.

   * `author'

     The plugin author. This can be whatever you like.

   * `desc'

     A general description of the plugin. This can be whatever you like.

   * `license'

     The plugin license type. The value can be one of
     `PLUGIN_LICENSE_PROPRIETARY', `PLUGIN_LICENSE_GPL', or
     `PLUGIN_LICENSE_BSD'.

   * `init'

     A once-only initialization function. This is executed when the
     plugin is loaded, which happens for *Note `INSTALL PLUGIN':
     install-plugin. or, for plugins listed in the `plugin' table, at
     server startup. The function takes no arguments. It returns zero
     for success and non-zero for failure. If an `init' function is
     unneeded for a plugin, it can be specified as 0.

   * `deinit'

     A once-only deinitialization function. This is executed when the
     plugin is unloaded, which happens for *Note `UNINSTALL PLUGIN':
     uninstall-plugin. or, for plugins listed in the `plugin' table, at
     server shutdown. The function takes no arguments. It returns zero
     for success and non-zero for failure. If a `deinit' function is
     unneeded for a plugin, it can be specified as 0.

   * `version'

     The plugin version number. When the plugin is installed, this
     value can be retrieved from the *Note
     `INFORMATION_SCHEMA.PLUGINS': plugins-table.  table. The value
     includes major and minor numbers. If you write the value as a hex
     constant, the format is `0xMMNN', where MM and `NN' are the major
     and minor numbers, respectively. For example, `0x0302' represents
     version 3.2.

   * `status_vars'

     A pointer to a structure for status variables associated with the
     plugin, or 0 if there are no such variables. When the plugin is
     installed, these variables are displayed in the output of the
     *Note `SHOW STATUS': show-status. statement.

   * `__reserved1', `__reserved2'

     These are placeholders for the future. Currently, they should be
     set to `NULL'.

The `init' and `deinit' functions in the general plugin declaration are
invoked only when loading and unloading the plugin. They have nothing
to do with use of the plugin such as happens when an SQL statement
causes the plugin to be invoked.

The `status_vars' member, if not 0, points to an array of
`st_mysql_show_var' structures, each of which describes one status
variable, followed by a structure with all members set to 0. The
`st_mysql_show_var' structure has this definition:

     struct st_mysql_show_var {
       const char *name;
       char *value;
       enum enum_mysql_show_type type;
     };

When the plugin is installed, the plugin name and the `name' value are
joined with an underscore to form the name displayed by *Note `SHOW
STATUS': show-status.

The following table shows the allowable status variable `type' values
and what the corresponding variable should be.

*Type*                 *Meaning*
`SHOW_BOOL'            Pointer to a boolean variable
`SHOW_INT'             Pointer to an integer variable
`SHOW_LONG'            Pointer to a long integer variable
`SHOW_LONGLONG'        Pointer to a longlong integer variable
`SHOW_CHAR'            A string
`SHOW_CHAR_PTR'        Pointer to a string
`SHOW_ARRAY'           Pointer to another `st_mysql_show_var' array
`SHOW_FUNC'            Pointer to a function

For the `SHOW_FUNC' type, the function is called and fills in its `out'
parameter, which then provides information about the variable to be
displayed. The function has this signature:

     #define SHOW_VAR_FUNC_BUFF_SIZE 1024

     typedef int (*mysql_show_var_func) (void *thd,
                                         struct st_mysql_show_var *out,
                                         char *buf);

Plugins should consider the `thd' parameter to be read only.


File: manual.info,  Node: plugin-api-type-specific,  Next: plugin-creating,  Prev: plugin-api-general,  Up: plugin-writing

21.2.3.2 Type-Specific Plugin Structures and Functions
......................................................

In the `st_mysql_plugin' structure that defines a plugin's general
declaration, the `info' member points to a type-specific plugin
descriptor. For a full-text parser plugin, the descriptor corresponds
to the `st_mysql_ftparser' structure in the `plugin.h' file:

     struct st_mysql_ftparser
     {
       int interface_version;
       int (*parse)(MYSQL_FTPARSER_PARAM *param);
       int (*init)(MYSQL_FTPARSER_PARAM *param);
       int (*deinit)(MYSQL_FTPARSER_PARAM *param);
     };

As shown by the structure definition, the descriptor has a version
number (`MYSQL_FTPARSER_INTERFACE_VERSION' for full-text parser
plugins) and contains pointers to three functions. The `init' and
`deinit' members should point to a function or be set to 0 if the
function is not needed. The `parse' member must point to the function
that performs the parsing.

A full-text parser plugin is used in two different contexts, indexing
and searching. In both contexts, the server calls the initialization
and deinitialization functions at the beginning and end of processing
each SQL statement that causes the plugin to be invoked. However,
during statement processing, the server calls the main parsing function
in context-specific fashion:

   * For indexing, the server calls the parser for each column value to
     be indexed.

   * For searching, the server calls the parser to parse the search
     string. The parser might also be called for rows processed by the
     statement. In natural language mode, there is no need for the
     server to call the parser. For boolean mode phrase searches or
     natural language searches with query expansion, the parser is used
     to parse column values for information that is not in the index.
     Also, if a boolean mode search is done for a column that has no
     `FULLTEXT' index, the built-in parser will be called. (Plugins are
     associated with specific indexes. If there is no index, no plugin
     is used.)

Note that the plugin declaration in the plugin library descriptor has
initialization and deinitialization functions, and so does the plugin
descriptor to which it points. These pairs of functions have different
purposes and are invoked for different reasons:

   * For the plugin declaration in the plugin library descriptor, the
     initialization and deinitialization functions are invoked when the
     plugin is loaded and unloaded.

   * For the plugin descriptor, the initialization and deinitialization
     functions are invoked per SQL statement for which the plugin is
     used.

Each interface function named in the plugin descriptor should return
zero for success or non-zero for failure, and each of them receives an
argument that points to a `MYSQL_FTPARSER_PARAM' structure containing
the parsing context. The structure has this definition:

     typedef struct st_mysql_ftparser_param
     {
       int (*mysql_parse)(struct st_mysql_ftparser_param *,
                          char *doc, int doc_len);
       int (*mysql_add_word)(struct st_mysql_ftparser_param *,
                             char *word, int word_len,
                             MYSQL_FTPARSER_BOOLEAN_INFO *boolean_info);
       void *ftparser_state;
       void *mysql_ftparam;
       struct charset_info_st *cs;
       char *doc;
       int length;
       int flags;
       enum enum_ftparser_mode mode;
     } MYSQL_FTPARSER_PARAM;

*Note*:

The definition shown is current as of MySQL 5.1.12. It is incompatible
with versions of MySQL 6.0 older than 5.1.12.

The structure members are used as follows:

   * `mysql_parse'

     A pointer to a callback function that invokes the server's
     built-in parser. Use this callback when the plugin acts as a front
     end to the built-in parser. That is, when the plugin parsing
     function is called, it should process the input to extract the
     text and pass the text to the `mysql_parse' callback.

     The first parameter for this callback function should be the
     `param' value itself:

          param->mysql_parse(param, ...);

     A front end plugin can extract text and pass it all at once to the
     built-in parser, or it can extract and pass text to the built-in
     parser a piece at a time. However, in this case, the built-in
     parser treats the pieces of text as though there are implicit word
     breaks between them.

   * `mysql_add_word'

     A pointer to a callback function that adds a word to a full-text
     index or to the list of search terms. Use this callback when the
     parser plugin replaces the built-in parser. That is, when the
     plugin parsing function is called, it should parse the input into
     words and invoke the `mysql_add_word' callback for each word.

     The first parameter for this callback function should be the
     `param' value itself:

          param->mysql_add_word(param, ...);

   * `ftparser_state'

     This is a generic pointer. The plugin can set it to point to
     information to be used internally for its own purposes.

   * `mysql_ftparam'

     This is set by the server. It is passed as the first argument to
     the `mysql_parse' or `mysql_add_word' callback.

   * `cs'

     A pointer to information about the character set of the text, or 0
     if no information is available.

   * `doc'

     A pointer to the text to be parsed.

   * `length'

     The length of the text to be parsed, in bytes.

   * `flags'

     Parser flags. This is zero if there are no special flags.
     Currently, the only non-zero flag is `MYSQL_FTFLAGS_NEED_COPY',
     which means that `mysql_add_word()' must save a copy of the word
     (that is, it cannot use a pointer to the word because the word is
     in a buffer that will be overwritten.)

     This flag might be set or reset by MySQL before calling the parser
     plugin, by the parser plugin itself, or by the `mysql_parse()'
     function.

   * `mode'

     The parsing mode. This value will be one of the folowing constants:

        * `MYSQL_FTPARSER_SIMPLE_MODE'

          Parse in fast and simple mode, which is used for indexing and
          for natural language queries. The parser should pass to the
          server only those words that should be indexed. If the parser
          uses length limits or a stopword list to determine which
          words to ignore, it should not pass such words to the server.

        * `MYSQL_FTPARSER_WITH_STOPWORDS'

          Parse in stopword mode. This is used in boolean searches for
          phrase matching. The parser should pass all words to the
          server, even stopwords or words that are outside any normal
          length limits.

        * `MYSQL_FTPARSER_FULL_BOOLEAN_INFO'

          Parse in boolean mode. This is used for parsing boolean query
          strings. The parser should recognize not only words but also
          boolean-mode operators and pass them to the server as tokens
          via the `mysql_add_word' callback. To tell the server what
          kind of token is being passed, the plugin needs to fill in a
          `MYSQL_FTPARSER_BOOLEAN_INFO' structure and pass a pointer to
          it.

If the parser is called in boolean mode, the `param->mode' value will be
`MYSQL_FTPARSER_FULL_BOOLEAN_INFO'. The `MYSQL_FTPARSER_BOOLEAN_INFO'
structure that the parser uses for passing token information to the
server looks like this:

     typedef struct st_mysql_ftparser_boolean_info
     {
       enum enum_ft_token_type type;
       int yesno;
       int weight_adjust;
       bool wasign;
       bool trunc;
       /* These are parser state and must be removed. */
       byte prev;
       byte *quot;
     } MYSQL_FTPARSER_BOOLEAN_INFO;

The parser should fill in the structure members as follows:

   * `type'

     The token type. This should be one of values shown in the
     following table.

     *Type*                      *Meaning*
     `FT_TOKEN_EOF'              End of data
     `FT_TOKEN_WORD'             A regular word
     `FT_TOKEN_LEFT_PAREN'       The beginning of a group or
                                 subexpression
     `FT_TOKEN_RIGHT_PAREN'      The end of a group or subexpression
     `FT_TOKEN_STOPWORD'         A stopword

   * `yesno'

     Whether the word must be present for a match to occur. 0 means
     that the word is optional but increases the match relevance if it
     is present. Values larger than 0 mean that the word must be
     present. Values smaller than 0 mean that the word must not be
     present.

   * `weight_adjust'

     A weighting factor that determines how much a match for the word
     counts. It can be used to increase or decrease the word's
     importance in relevance calculations. A value of zero indicates no
     weight adjustment. Values greater than or less than zero mean
     higher or lower weight, respectively. The examples at *Note
     fulltext-boolean::, that use the `<' and `>' operators illustrate
     how weighting works.

   * `wasign'

     The sign of the weighting factor. A negative value acts like the
     `~' boolean-search operator, which causes the word's contribution
     to the relevance to be negative.

   * `trunc'

     Whether matching should be done as if the boolean-mode `*'
     truncation operator had been given.

Plugins should not use the `prev' and `quot' members of the
`MYSQL_FTPARSER_BOOLEAN_INFO' structure.


File: manual.info,  Node: plugin-creating,  Prev: plugin-api-type-specific,  Up: plugin-writing

21.2.3.3 Creating a Plugin Library
..................................

This section provides a step-by-step procedure for creating a plugin
library. It shows how to develop a library that contains a full-text
parsing plugin named `simple_parser'. This plugin performs parsing
based on simpler rules than those used by the MySQL built-in full-text
parser: Words are non-empty runs of whitespace characters.

Each plugin library has the following contents:

   * A plugin library descriptor that indicates the version number of
     the general plugin API that the library uses and that contains a
     general declaration for each plugin in the library.

   * Each plugin general declaration contains information that is
     common to all types of plugin: A value that indicates the plugin
     type; the plugin name, author, description, and license type; and
     pointers to the initialization and deinitialization functions that
     the server invokes when it loads and unloads the plugin.

   * The plugin general declaration also contains a pointer to a
     type-specific plugin descriptor. The structure of these
     descriptors can vary from one plugin type to another, because each
     type of plugin can have its own API. A plugin descriptor contains
     a type-specific API version number and pointers to the functions
     that are needed to implement that plugin type. For example, a
     full-text parser plugin has initialization and deinitialization
     functions, and a main parsing function. The server invokes these
     functions when it uses the plugin to parse text.

   * The plugin library contains the interface functions that are
     referenced by the library descriptor and by the plugin descriptors.

The easiest way to follow the instructions in this section is to use
the source code in the `plugin/fulltext' directory of a MySQL source
distribution. The instructions assume that you make a copy of that
directory and use it to build the plugin library.  To make a copy of
the directory, use the following commands, which assume that the MySQL
source tree is in a directory named `mysql-6.0' under your current
directory:

     shell> mkdir fulltext_plugin
     shell> cp mysql-6.0/plugin/fulltext/* fulltext_plugin

If you are copying files from a Bazaar source tree, `cp' will display
an error message about the `SCCS' directory, which you can ignore.

After copying the source files, use the following procedure to create a
plugin library:

  1. Change location into the `fulltext_plugin' directory:

          shell> cd fulltext_plugin

  2. The plugin source file should include the header files that the
     plugin library needs. The `plugin.h' file is required, and the
     library might require other files as well. For example:

          #include <stdlib.h>
          #include <ctype.h>
          #include <mysql/plugin.h>

  3. Set up the plugin library file descriptor.

     Every plugin library must include a library descriptor that must
     define two symbols:

        * `_mysql_plugin_interface_version_' specifies the version
          number of the general plugin framework. This is given by the
          `MYSQL_PLUGIN_INTERFACE_VERSION' symbol, which is defined in
          the `plugin.h' file.

        * `_mysql_plugin_declarations_' defines an array of plugin
          declarations, terminated by a declaration with all members
          set to 0. Each declaration is an instance of the
          `st_mysql_plugin' structure (also defined in `plugin.h').
          There must be one of these for each plugin in the library.

     If the server does not find these two symbols in a library, it
     does not accept it as a legal plugin library and rejects it with
     an error. This prevents use of a library for plugin purposes
     unless it was built specifically as a plugin library.

     The standard (and most convenient) way to define the two required
     symbols is by using the `mysql_declare_plugin' and
     `mysql_declare_plugin_end' macros from the `plugin.h' file:

          mysql_declare_plugin
           ... ONE OR MORE PLUGIN DECLARATIONS HERE ...
          mysql_declare_plugin_end;

     For example, the library descriptor for a library that contains a
     single plugin named `simple_parser' looks like this:

          mysql_declare_plugin
          {
            MYSQL_FTPARSER_PLUGIN,      /* type                            */
            &simple_parser_descriptor,  /* descriptor                      */
            "simple_parser",            /* name                            */
            "MySQL AB",                 /* author                          */
            "Simple Full-Text Parser",  /* description                     */
            PLUGIN_LICENSE_GPL,         /* plugin license                  */
            simple_parser_plugin_init,  /* init function (when loaded)     */
            simple_parser_plugin_deinit,/* deinit function (when unloaded) */
            0x0001,                     /* version                         */
            simple_status               /* status variables                */
          }
          mysql_declare_plugin_end;

     For a full-text parser plugin, the type must be
     `MYSQL_FTPARSER_PLUGIN'. This is the value that identifies the
     plugin as being legal for use in a `WITH PARSER' clause when
     creating a `FULLTEXT' index. (No other plugin type is legal for
     this clause.)

     The `mysql_declare_plugin' and `mysql_declare_plugin_end' macros
     are defined in `plugin.h' like this:

          #ifndef MYSQL_DYNAMIC_PLUGIN
          #define __MYSQL_DECLARE_PLUGIN(NAME, VERSION, PSIZE, DECLS)           \
          int VERSION= MYSQL_PLUGIN_INTERFACE_VERSION;                          \
          int PSIZE= sizeof(struct st_mysql_plugin);                            \
          struct st_mysql_plugin DECLS[]= {
          #else
          #define __MYSQL_DECLARE_PLUGIN(NAME, VERSION, PSIZE, DECLS)           \
          int _mysql_plugin_interface_version_= MYSQL_PLUGIN_INTERFACE_VERSION; \
          int _mysql_sizeof_struct_st_plugin_= sizeof(struct st_mysql_plugin);  \
          struct st_mysql_plugin _mysql_plugin_declarations_[]= {
          #endif

          #define mysql_declare_plugin(NAME) \
          __MYSQL_DECLARE_PLUGIN(NAME, \
                           builtin_ ## NAME ## _plugin_interface_version, \
                           builtin_ ## NAME ## _sizeof_struct_st_plugin, \
                           builtin_ ## NAME ## _plugin)

          #define mysql_declare_plugin_end ,{0,0,0,0,0,0,0,0,0}}

     One point to note about those definitions is that the
     `_mysql_plugin_interface_version_' symbol is defined only if the
     `MYSQL_DYNAMIC_PLUGIN' symbol is defined.  This means that you'll
     need to provide `-DMYSQL_DYNAMIC_PLUGIN' as part of the
     compilation command when you build the plugin.

     When the macros are used as just shown, they expand to the
     following code, which defines both of the required symbols
     (`_mysql_plugin_interface_version_' and
     `_mysql_plugin_declarations_'):

          int _mysql_plugin_interface_version_= MYSQL_PLUGIN_INTERFACE_VERSION;
          struct st_mysql_plugin _mysql_plugin_declarations_[]= {
          {
            MYSQL_FTPARSER_PLUGIN,      /* type                            */
            &simple_parser_descriptor,  /* descriptor                      */
            "simple_parser",            /* name                            */
            "MySQL AB",                 /* author                          */
            "Simple Full-Text Parser",  /* description                     */
            PLUGIN_LICENSE_GPL,         /* plugin license                  */
            simple_parser_plugin_init,  /* init function (when loaded)     */
            simple_parser_plugin_deinit,/* deinit function (when unloaded) */
            0x0001,                     /* version                         */
            simple_status               /* status variables                */
          }
            ,{0,0,0,0,0,0,00,0}
          };

     The preceding example declares a single plugin in the library
     descriptor, but it is possible to declare multiple plugins. List
     the declarations one after the other between
     `mysql_declare_plugin' and `mysql_declare_plugin_end', separated by
     commas.

     MySQL plugins can be written in C or C++ (or another language that
     can use C calling conventions). One feature of C++ is that you can
     use non-constant variables to initialize global structures.
     However, if you write a C++ plugin, you should not use this
     feature. Members of structures such as the `st_mysql_plugin'
     structure should be initialized with constant variables.  See the
     discussion at the end of this section that describes some legal
     and illegal initializers for plugins.

  4. Set up the plugin descriptor.

     Each plugin declaration in the library descriptor points to a
     type-specific descriptor for the corresponding plugin. In the
     `simple_parser' declaration, that descriptor is indicated by
     `&simple_parser_descriptor'. The descriptor specifies the version
     number for the full-text plugin interface (as given by
     `MYSQL_FTPARSER_INTERFACE_VERSION'), and the plugin's parsing,
     initialization, and deinitialization functions:

          static struct st_mysql_ftparser simple_parser_descriptor=
          {
            MYSQL_FTPARSER_INTERFACE_VERSION, /* interface version      */
            simple_parser_parse,              /* parsing function       */
            simple_parser_init,               /* parser init function   */
            simple_parser_deinit              /* parser deinit function */
          };

  5. Set up the plugin interface functions.

     The general plugin declaration in the library descriptor names the
     initialization and deinitialization functions that the server
     should invoke when it loads and unloads the plugin. For
     `simple_parser', these functions do nothing but return zero to
     indicate that they succeeded:

          static int simple_parser_plugin_init(void)
          {
            return(0);
          }

          static int simple_parser_plugin_deinit(void)
          {
            return(0);
          }

     Because those functions do not actually do anything, you could
     omit them and specify 0 for each of them in the plugin declaration.

     The type-specific plugin descriptor for `simple_parser' names the
     initialization, deinitialization, and parsing functions that the
     server invokes when the plugin is used. For `simple_parser', the
     initialization and deinitialization functions do nothing:

          static int simple_parser_init(MYSQL_FTPARSER_PARAM *param)
          {
            return(0);
          }

          static int simple_parser_deinit(MYSQL_FTPARSER_PARAM *param)
          {
            return(0);
          }

     Here too, because those functions do nothing, you could omit them
     and specify 0 for each of them in the plugin descriptor.

     The main parsing function, `simple_parser_parse()', acts as a
     replacement for the built-in full-text parser, so it needs to
     split text into words and pass each word to the server.  The
     parsing function's first argument is a pointer to a structure that
     contains the parsing context. This structure has a `doc' member
     that points to the text to be parsed, and a `length' member that
     indicates how long the text is. The simple parsing done by the
     plugin considers non-empty runs of whitespace characters to be
     words, so it identifies words like this:

          static int simple_parser_parse(MYSQL_FTPARSER_PARAM *param)
          {
            char *end, *start, *docend= param->doc + param->length;

            for (end= start= param->doc;; end++)
            {
              if (end == docend)
              {
                if (end > start)
                  add_word(param, start, end - start);
                break;
              }
              else if (isspace(*end))
              {
                if (end > start)
                  add_word(param, start, end - start);
                start= end + 1;
              }
            }
            return(0);
          }

     As the parser finds each word, it invokes a function `add_word()'
     to pass the word to the server. `add_word()' is a helper function
     only; it is not part of the plugin interface. The parser passes
     the parsing context pointer to `add_word()', as well as a pointer
     to the word and a length value:

          static void add_word(MYSQL_FTPARSER_PARAM *param, char *word, size_t len)
          {
            MYSQL_FTPARSER_BOOLEAN_INFO bool_info=
              { FT_TOKEN_WORD, 0, 0, 0, 0, ' ', 0 };

            param->mysql_add_word(param, word, len, &bool_info);
          }

     For boolean-mode parsing, `add_word()' fills in the members of the
     `bool_info' structure as described in *Note
     plugin-api-type-specific::.

  6. Set up the status variables, if there are any. For the
     `simple_parser' plugin, the following status variable array sets
     up one status variable with a value that is static text, and
     another with a value that is stored in a long integer variable:

          long number_of_calls= 0;

          struct st_mysql_show_var simple_status[]=
          {
            {"static", (char *)"just a static text", SHOW_CHAR},
            {"called", (char *)&number_of_calls,     SHOW_LONG},
            {0,0,0}
          };

     When the plugin is installed, the plugin name and the `name' value
     are joined with an underscore to form the name displayed by *Note
     `SHOW STATUS': show-status. For the array just shown, the
     resulting status variable names are `simple_parser_static' and
     `simple_parser_called'. This convention means that you can easily
     display the variables for a plugin using its name:

          mysql> SHOW STATUS LIKE 'simple_parser%';
          +----------------------+--------------------+
          | Variable_name        | Value              |
          +----------------------+--------------------+
          | simple_parser_static | just a static text |
          | simple_parser_called | 0                  |
          +----------------------+--------------------+

  7. Compile the plugin library as a shared library and install it in
     the plugin directory.

     *Note*:

     As mentioned earlier, be sure to specify `-DMYSQL_DYNAMIC_PLUGIN'
     as part of the compilation command when you build the plugin.

     The procedure for compiling shared objects varies from system to
     system. If you build your library using the GNU autotools,
     `libtool' should be able to generate the correct compilation
     commands for your system.  If the library is named `mypluglib', you
     should end up with a shared object file that has a name something
     like `libmypluglib.so'. (The file name might have a different
     extension on your system.)

     To use the autotools, you'll need to make a few changes to the
     configuration files at this point to enable the plugin to be
     compiled and installed. Assume that your MySQL distribution is
     installed at a base directory of `/usr/local/mysql' and that its
     header files are located in the `include' directory under the base
     directory.

     Edit `Makefile.am', which should look something like this:

          #Makefile.am example for a plugin

          pkglibdir=$(libdir)/mysql
          INCLUDES= -I$(top_builddir)/include -I$(top_srcdir)/include
          #noinst_LTLIBRARIES= mypluglib.la
          pkglib_LTLIBRARIES= mypluglib.la
          mypluglib_la_SOURCES= plugin_example.c
          mypluglib_la_LDFLAGS= -module -rpath $(pkglibdir)
          mypluglib_la_CFLAGS= -DMYSQL_DYNAMIC_PLUGIN

     The `mypluglib_la_CFLAGS' line takes care of passing the
     `-DMYSQL_DYNAMIC_PLUGIN' flag to the compilation command.

     Adjust the `INCLUDES' line to specify the path name to the
     installed MySQL header files. Edit it to look like this:

          INCLUDES= -I/usr/local/mysql/include

     Make sure that the `noinst_LTLIBRARIES' line is commented out or
     remove it. Make sure that the `pkglib_LTLIBRARIES' line is not
     commented out; it enables the `make install' command.

     Set up the files needed for the `configure' command, invoke it,
     and run `make':

          shell> autoreconf --force --install --symlink
          shell> ./configure --prefix=/usr/local/mysql
          shell> make

     The `--prefix' option to `configure' indicates the MySQL base
     directory under which the plugin should be installed. You can see
     what value to use for this option with *Note `SHOW VARIABLES':
     show-variables.:

          mysql> SHOW VARIABLES LIKE 'basedir';
          +---------------+------------------+
          | Variable_name | Value            |
          +---------------+------------------+
          | base          | /usr/local/mysql |
          +---------------+------------------+

     The location of the plugin directory where you should install the
     library is given by the `plugin_dir' system variable. For example:

          mysql> SHOW VARIABLES LIKE 'plugin_dir';
          +---------------+-----------------------------------+
          | Variable_name | Value                             |
          +---------------+-----------------------------------+
          | plugin_dir    | /usr/local/mysql/lib/mysql/plugin |
          +---------------+-----------------------------------+

     To install the plugin library, use `make':

          shell> make install

     Verify that `make install' installed the plugin library in the
     proper directory. After installing it, make sure that the library
     permissions allow it to be executed by the server.

  8. Register the plugin with the server.

     The *Note `INSTALL PLUGIN': install-plugin.  statement causes the
     server to list the plugin in the `plugin' table and to load the
     plugin code from the library file. Use that statement to register
     `simple_parser' with the server, and then verify that the plugin
     is listed in the `plugin' table:

          mysql> INSTALL PLUGIN simple_parser SONAME 'libmypluglib.so';
          Query OK, 0 rows affected (0.00 sec)

          mysql> SELECT * FROM mysql.plugin;
          +---------------+-----------------+
          | name          | dl              |
          +---------------+-----------------+
          | simple_parser | libmypluglib.so |
          +---------------+-----------------+
          1 row in set (0.00 sec)

  9. Try the plugin.

     Create a table that contains a string column and associate the
     parser plugin with a `FULLTEXT' index on the column:

          mysql> CREATE TABLE t (c VARCHAR(255),
              ->   FULLTEXT (c) WITH PARSER simple_parser);
          Query OK, 0 rows affected (0.01 sec)

     Insert some text into the table and try some searches.  These
     should verify that the parser plugin treats all non-whitespace
     characters as word characters:

          mysql> INSERT INTO t VALUES
              ->   ('latin1_general_cs is a case-sensitive collation'),
              ->   ('I\'d like a case of oranges'),
              ->   ('this is sensitive information'),
              ->   ('another row'),
              ->   ('yet another row');
          Query OK, 5 rows affected (0.02 sec)
          Records: 5  Duplicates: 0  Warnings: 0

          mysql> SELECT c FROM t;
          +-------------------------------------------------+
          | c                                               |
          +-------------------------------------------------+
          | latin1_general_cs is a case-sensitive collation |
          | I'd like a case of oranges                      |
          | this is sensitive information                   |
          | another row                                     |
          | yet another row                                 |
          +-------------------------------------------------+
          5 rows in set (0.00 sec)

          mysql> SELECT MATCH(c) AGAINST('case') FROM t;
          +--------------------------+
          | MATCH(c) AGAINST('case') |
          +--------------------------+
          |                        0 |
          |          1.2968142032623 |
          |                        0 |
          |                        0 |
          |                        0 |
          +--------------------------+
          5 rows in set (0.00 sec)

          mysql> SELECT MATCH(c) AGAINST('sensitive') FROM t;
          +-------------------------------+
          | MATCH(c) AGAINST('sensitive') |
          +-------------------------------+
          |                             0 |
          |                             0 |
          |               1.3253291845322 |
          |                             0 |
          |                             0 |
          +-------------------------------+
          5 rows in set (0.01 sec)

          mysql> SELECT MATCH(c) AGAINST('case-sensitive') FROM t;
          +------------------------------------+
          | MATCH(c) AGAINST('case-sensitive') |
          +------------------------------------+
          |                    1.3109166622162 |
          |                                  0 |
          |                                  0 |
          |                                  0 |
          |                                  0 |
          +------------------------------------+
          5 rows in set (0.01 sec)

          mysql> SELECT MATCH(c) AGAINST('I\'d') FROM t;
          +--------------------------+
          | MATCH(c) AGAINST('I\'d') |
          +--------------------------+
          |                        0 |
          |          1.2968142032623 |
          |                        0 |
          |                        0 |
          |                        0 |
          +--------------------------+
          5 rows in set (0.01 sec)

Note how neither `case' nor `insensitive' match `case-insensitive' the
way that they would for the built-in parser.

MySQL plugins can be written in C or C++ (or another language that can
use C calling conventions). One feature of C++ is that you can use
non-constant variables to initialize global structures. However, if you
write a C++ plugin, you should not use this feature. Members of
structures such as the `st_mysql_plugin' structure should be
initialized with constant variables. The `simple_parser' descriptor
shown earlier is allowable in a C++ plugin because it satisfies that
requirement:

     mysql_declare_plugin
     {
       MYSQL_FTPARSER_PLUGIN,      /* type                            */
       &simple_parser_descriptor,  /* descriptor                      */
       "simple_parser",            /* name                            */
       "MySQL AB",                 /* author                          */
       "Simple Full-Text Parser",  /* description                     */
       PLUGIN_LICENSE_GPL,         /* plugin license                  */
       simple_parser_plugin_init,  /* init function (when loaded)     */
       simple_parser_plugin_deinit,/* deinit function (when unloaded) */
       0x0001,                     /* version                         */
       simple_status               /* status variables                */
     }
     mysql_declare_plugin_end;

Here is another valid way to write the descriptor. It uses constant
variables to indicate the plugin name, author, and description:

     const char *simple_parser_name = "simple_parser";
     const char *simple_parser_author = "MySQL AB";
     const char *simple_parser_description = "Simple Full-Text Parser";

     mysql_declare_plugin
     {
       MYSQL_FTPARSER_PLUGIN,      /* type                            */
       &simple_parser_descriptor,  /* descriptor                      */
       simple_parser_name,         /* name                            */
       simple_parser_author,       /* author                          */
       simple_parser_description,  /* description                     */
       PLUGIN_LICENSE_GPL,         /* plugin license                  */
       simple_parser_plugin_init,  /* init function (when loaded)     */
       simple_parser_plugin_deinit,/* deinit function (when unloaded) */
       0x0001,                     /* version                         */
       simple_status               /* status variables                */
     }
     mysql_declare_plugin_end;

However, the following descriptor is invalid. It uses structure members
to indicate the plugin name, author, and description, but structures
are not considered constant initializers in C++:

     typedef struct
     {
       const char *name;
       const char *author;
       const char *description;
     } plugin_info;

     plugin_info parser_info = {
       "simple_parser",
       "MySQL AB",
       "Simple Full-Text Parser"
     };

     mysql_declare_plugin
     {
       MYSQL_FTPARSER_PLUGIN,      /* type                            */
       &simple_parser_descriptor,  /* descriptor                      */
       parser_info.name,           /* name                            */
       parser_info.author,         /* author                          */
       parser_info.description,    /* description                     */
       PLUGIN_LICENSE_GPL,         /* plugin license                  */
       simple_parser_plugin_init,  /* init function (when loaded)     */
       simple_parser_plugin_deinit,/* deinit function (when unloaded) */
       0x0001,                     /* version                         */
       simple_status               /* status variables                */
     }
     mysql_declare_plugin_end;


File: manual.info,  Node: adding-functions,  Next: adding-procedures,  Prev: plugin-api,  Up: extending-mysql

21.3 Adding New Functions to MySQL
==================================

* Menu:

* udf-features::                 Features of the User-Defined Function Interface
* adding-udf::                   Adding a New User-Defined Function
* adding-native-function::       Adding a New Native Function

There are three ways to add new functions to MySQL:

   * You can add functions through the user-defined function (UDF)
     interface. User-defined functions are compiled as object files and
     then added to and removed from the server dynamically using the
     *Note `CREATE FUNCTION': create-function. and *Note `DROP
     FUNCTION': drop-function. statements. See *Note
     create-function-udf::.

   * You can add functions as native (built-in) MySQL functions.
     Native functions are compiled into the *Note `mysqld': mysqld.
     server and become available on a permanent basis.

   * Another way to add functions is by creating stored functions.
     These are written using SQL statements rather than by compiling
     object code. The syntax for writing stored functions is not
     covered here. See *Note stored-routines::.

Each method of creating compiled functions has advantages and
disadvantages:

   * If you write user-defined functions, you must install object files
     in addition to the server itself. If you compile your function
     into the server, you don't need to do that.

   * Native functions require you to modify a source distribution.
     UDFs do not. You can add UDFs to a binary MySQL distribution.  No
     access to MySQL source is necessary.

   * If you upgrade your MySQL distribution, you can continue to use
     your previously installed UDFs, unless you upgrade to a newer
     version for which the UDF interface changes. For native functions,
     you must repeat your modifications each time you upgrade.

Whichever method you use to add new functions, they can be invoked in
SQL statements just like native functions such as `ABS()' or
`SOUNDEX()'.

See *Note function-resolution::, for the rules describing how the
server interprets references to different kinds of functions.

The following sections describe features of the UDF interface, provide
instructions for writing UDFs, discuss security precautions that MySQL
takes to prevent UDF misuse, and describe how to add native MySQL
functions.

For example source code that illustrates how to write UDFs, take a look
at the `sql/udf_example.c' file that is provided in MySQL source
distributions.


File: manual.info,  Node: udf-features,  Next: adding-udf,  Prev: adding-functions,  Up: adding-functions

21.3.1 Features of the User-Defined Function Interface
------------------------------------------------------

The MySQL interface for user-defined functions provides the following
features and capabilities:

   * Functions can return string, integer, or real values and can
     accept arguments of those same types.

   * You can define simple functions that operate on a single row at a
     time, or aggregate functions that operate on groups of rows.

   * Information is provided to functions that enables them to check
     the number, types, and names of the arguments passed to them.

   * You can tell MySQL to coerce arguments to a given type before
     passing them to a function.

   * You can indicate that a function returns `NULL' or that an error
     occurred.


File: manual.info,  Node: adding-udf,  Next: adding-native-function,  Prev: udf-features,  Up: adding-functions

21.3.2 Adding a New User-Defined Function
-----------------------------------------

* Menu:

* udf-calling::                  UDF Calling Sequences for Simple Functions
* udf-aggr-calling::             UDF Calling Sequences for Aggregate Functions
* udf-arguments::                UDF Argument Processing
* udf-return-values::            UDF Return Values and Error Handling
* udf-compiling::                Compiling and Installing User-Defined Functions
* udf-security::                 User-Defined Function Security Precautions

For the UDF mechanism to work, functions must be written in C or C++
and your operating system must support dynamic loading. The MySQL
source distribution includes a file `sql/udf_example.c' that defines 5
new functions. Consult this file to see how UDF calling conventions
work. UDF-related symbols and data structures are defined in the
`include/mysql_com.h' header file. (You need not include this header
file directly because it is included by `mysql.h'.)

A UDF contains code that becomes part of the running server, so when
you write a UDF, you are bound by any and all constraints that
otherwise apply to writing server code. For example, you may have
problems if you attempt to use functions from the `libstdc++' library.
These constraints may change in future versions of the server, so it is
possible that server upgrades will require revisions to UDFs that were
originally written for older servers. For information about these
constraints, see *Note configure-options::, and *Note
compilation-problems::.

To be able to use UDFs, you need to link *Note `mysqld': mysqld.
dynamically. Don't configure MySQL using
`--with-mysqld-ldflags=-all-static'. If you want to use a UDF that
needs to access symbols from *Note `mysqld': mysqld. (for example, the
`metaphone' function in `sql/udf_example.c' that uses
`default_charset_info'), you must link the program with `-rdynamic'
(see `man dlopen'). If you plan to use UDFs, the rule of thumb is to
configure MySQL with `--with-mysqld-ldflags=-rdynamic' unless you have
a very good reason not to.

For each function that you want to use in SQL statements, you should
define corresponding C (or C++) functions. In the following discussion,
the name `xxx' is used for an example function name. To distinguish
between SQL and C/C++ usage, `XXX()' (uppercase) indicates an SQL
function call, and `xxx()' (lowercase) indicates a C/C++ function call.

The C/C++ functions that you write to implement the interface for
`XXX()' are:

   * `xxx()' (required)

     The main function. This is where the function result is computed.
     The correspondence between the SQL function data type and the
     return type of your C/C++ function is shown here.

     *SQL Type*        *C/C++ Type*
     `STRING'          `char *'
     *Note `INTEGER':  `long long'
     numeric-types.    
     *Note `REAL':     `double'
     numeric-types.    

     It is also possible to declare a *Note `DECIMAL': numeric-types.
     function, but currently the value is returned as a string, so you
     should write the UDF as though it were a `STRING' function. `ROW'
     functions are not implemented.

   * `xxx_init()' (optional)

     The initialization function for `xxx()'. It can be used for the
     following purposes:

        * To check the number of arguments to `XXX()'.

        * To check that the arguments are of a required type or,
          alternatively, to tell MySQL to coerce arguments to the types
          you want when the main function is called.

        * To allocate any memory required by the main function.

        * To specify the maximum length of the result.

        * To specify (for *Note `REAL': numeric-types.  functions) the
          maximum number of decimal places in the result.

        * To specify whether the result can be `NULL'.

   * `xxx_deinit()' (optional)

     The deinitialization function for `xxx()'.  It should deallocate
     any memory allocated by the initialization function.

When an SQL statement invokes `XXX()', MySQL calls the initialization
function `xxx_init()' to let it perform any required setup, such as
argument checking or memory allocation. If `xxx_init()' returns an
error, MySQL aborts the SQL statement with an error message and does
not call the main or deinitialization functions.  Otherwise, MySQL
calls the main function `xxx()' once for each row. After all rows have
been processed, MySQL calls the deinitialization function
`xxx_deinit()' so that it can perform any required cleanup.

For aggregate functions that work like `SUM()', you must also provide
the following functions:

   * `xxx_clear()'

     Reset the current aggregate value but do not insert the argument
     as the initial aggregate value for a new group.

   * `xxx_add()'

     Add the argument to the current aggregate value.

MySQL handles aggregate UDFs as follows:

  1. Call `xxx_init()' to let the aggregate function allocate any
     memory it needs for storing results.

  2. Sort the table according to the `GROUP BY' expression.

  3. Call `xxx_clear()' for the first row in each new group.

  4. Call `xxx_add()' for each row that belongs in the same group.

  5. Call `xxx()' to get the result for the aggregate when the group
     changes or after the last row has been processed.

  6. Repeat 3-5 until all rows has been processed

  7. Call `xxx_deinit()' to let the UDF free any memory it has
     allocated.

All functions must be thread-safe. This includes not just the main
function, but the initialization and deinitialization functions as
well, and also the additional functions required by aggregate
functions. A consequence of this requirement is that you are not
allowed to allocate any global or static variables that change! If you
need memory, you should allocate it in `xxx_init()' and free it in
`xxx_deinit()'.


File: manual.info,  Node: udf-calling,  Next: udf-aggr-calling,  Prev: adding-udf,  Up: adding-udf

21.3.2.1 UDF Calling Sequences for Simple Functions
...................................................

This section describes the different functions that you need to define
when you create a simple UDF.  *Note adding-udf::, describes the order
in which MySQL calls these functions.

The main `xxx()' function should be declared as shown in this section.
Note that the return type and parameters differ, depending on whether
you declare the SQL function `XXX()' to return `STRING', *Note
`INTEGER': numeric-types, or *Note `REAL': numeric-types. in the *Note
`CREATE FUNCTION': create-function. statement:

For `STRING' functions:

     char *xxx(UDF_INIT *initid, UDF_ARGS *args,
               char *result, unsigned long *length,
               char *is_null, char *error);

For *Note `INTEGER': numeric-types. functions:

     long long xxx(UDF_INIT *initid, UDF_ARGS *args,
                   char *is_null, char *error);

For *Note `REAL': numeric-types. functions:

     double xxx(UDF_INIT *initid, UDF_ARGS *args,
                   char *is_null, char *error);

*Note `DECIMAL': numeric-types. functions return string values and
should be declared the same way as `STRING' functions. `ROW' functions
are not implemented.

The initialization and deinitialization functions are declared like
this:

     my_bool xxx_init(UDF_INIT *initid, UDF_ARGS *args, char *message);

     void xxx_deinit(UDF_INIT *initid);

The `initid' parameter is passed to all three functions. It points to a
`UDF_INIT' structure that is used to communicate information between
functions. The `UDF_INIT' structure members follow. The initialization
function should fill in any members that it wishes to change. (To use
the default for a member, leave it unchanged.)

   * `my_bool maybe_null'

     `xxx_init()' should set `maybe_null' to `1' if `xxx()' can return
     `NULL'. The default value is `1' if any of the arguments are
     declared `maybe_null'.

   * `unsigned int decimals'

     The number of decimal digits to the right of the decimal point.
     The default value is the maximum number of decimal digits in the
     arguments passed to the main function. For example, if the
     function is passed `1.34', `1.345', and `1.3', the default would
     be 3, because `1.345' has 3 decimal digits.

     For arguments that have no fixed number of decimals, the
     `decimals' value is set to 31, which is 1 more than the maximum
     number of decimals allowed for the *Note `DECIMAL': numeric-types,
     *Note `FLOAT': numeric-types, and *Note `DOUBLE': numeric-types.
     data types. As of MySQL 6.0.6, this value is available as the
     constant `NOT_FIXED_DEC' in the `mysql_com.h' header file.

     A `decimals' value of 31 is used for arguments in cases such as a
     *Note `FLOAT': numeric-types. or *Note `DOUBLE': numeric-types.
     column declared without an explicit number of decimals (for
     example, *Note `FLOAT': numeric-types. rather than `FLOAT(10,3)')
     and for floating-point constants such as `1345E-3'. It is also
     used for string and other non-number arguments that might be
     converted within the function to numeric form.

     The value to which the `decimals' member is initialized is only a
     default. It can be changed within the function to reflect the
     actual calculation performed.  The default is determined such that
     the largest number of decimals of the arguments is used. If the
     number of decimals is `NOT_FIXED_DEC' for even one of the
     arguments, that is the value used for `decimals'.

   * `unsigned int max_length'

     The maximum length of the result. The default `max_length' value
     differs depending on the result type of the function. For string
     functions, the default is the length of the longest argument. For
     integer functions, the default is 21 digits. For real functions,
     the default is 13 plus the number of decimal digits indicated by
     `initid->decimals'. (For numeric functions, the length includes
     any sign or decimal point characters.)

     If you want to return a blob value, you can set `max_length' to
     65KB or 16MB. This memory is not allocated, but the value is used
     to decide which data type to use if there is a need to temporarily
     store the data.

   * `char *ptr'

     A pointer that the function can use for its own purposes.  For
     example, functions can use `initid->ptr' to communicate allocated
     memory among themselves. `xxx_init()' should allocate the memory
     and assign it to this pointer:

          initid->ptr = allocated_memory;

     In `xxx()' and `xxx_deinit()', refer to `initid->ptr' to use or
     deallocate the memory.

   * `my_bool const_item'

     `xxx_init()' should set `const_item' to `1' if `xxx()' always
     returns the same value and to `0' otherwise.


File: manual.info,  Node: udf-aggr-calling,  Next: udf-arguments,  Prev: udf-calling,  Up: adding-udf

21.3.2.2 UDF Calling Sequences for Aggregate Functions
......................................................

This section describes the different functions that you need to define
when you create an aggregate UDF.  *Note adding-udf::, describes the
order in which MySQL calls these functions.

   * `xxx_reset()'

     This function is called when MySQL finds the first row in a new
     group. It should reset any internal summary variables and then use
     the given `UDF_ARGS' argument as the first value in your internal
     summary value for the group. Declare `xxx_reset()' as follows:

          void xxx_reset(UDF_INIT *initid, UDF_ARGS *args,
                         char *is_null, char *error);

     `xxx_reset()' is not needed or used in MySQL 6.0, in which the UDF
     interface uses `xxx_clear()' instead. However, you can define both
     `xxx_reset()' and `xxx_clear()' if you want to have your UDF work
     with older versions of the server. (If you do include both
     functions, the `xxx_reset()' function in many cases can be
     implemented internally by calling `xxx_clear()' to reset all
     variables, and then calling `xxx_add()' to add the `UDF_ARGS'
     argument as the first value in the group.)

   * `xxx_clear()'

     This function is called when MySQL needs to reset the summary
     results. It is called at the beginning for each new group but can
     also be called to reset the values for a query where there were no
     matching rows. Declare `xxx_clear()' as follows:

          void xxx_clear(UDF_INIT *initid, char *is_null, char *error);

     `is_null' is set to point to `CHAR(0)' before calling
     `xxx_clear()'.

     If something went wrong, you can store a value in the variable to
     which the `error' argument points. `error' points to a single-byte
     variable, not to a string buffer.

     `xxx_clear()' is required by MySQL 6.0.

   * `xxx_add()'

     This function is called for all rows that belong to the same
     group. You should use it to add the value in the `UDF_ARGS'
     argument to your internal summary variable.

          void xxx_add(UDF_INIT *initid, UDF_ARGS *args,
                       char *is_null, char *error);

The `xxx()' function for an aggregate UDF should be declared the same
way as for a non-aggregate UDF.  See *Note udf-calling::.

For an aggregate UDF, MySQL calls the `xxx()' function after all rows
in the group have been processed. You should normally never access its
`UDF_ARGS' argument here but instead return a value based on your
internal summary variables.

Return value handling in `xxx()' should be done the same way as for a
non-aggregate UDF. See *Note udf-return-values::.

The `xxx_reset()' and `xxx_add()' functions handle their `UDF_ARGS'
argument the same way as functions for non-aggregate UDFs. See *Note
udf-arguments::.

The pointer arguments to `is_null' and `error' are the same for all
calls to `xxx_reset()', `xxx_clear()', `xxx_add()' and `xxx()'. You can
use this to remember that you got an error or whether the `xxx()'
function should return `NULL'. You should not store a string into
`*error'!  `error' points to a single-byte variable, not to a string
buffer.

`*is_null' is reset for each group (before calling `xxx_clear()').
`*error' is never reset.

If `*is_null' or `*error' are set when `xxx()' returns, MySQL returns
`NULL' as the result for the group function.


File: manual.info,  Node: udf-arguments,  Next: udf-return-values,  Prev: udf-aggr-calling,  Up: adding-udf

21.3.2.3 UDF Argument Processing
................................

The `args' parameter points to a `UDF_ARGS' structure that has the
members listed here:

   * `unsigned int arg_count'

     The number of arguments. Check this value in the initialization
     function if you require your function to be called with a
     particular number of arguments. For example:

          if (args->arg_count != 2)
          {
              strcpy(message,"XXX() requires two arguments");
              return 1;
          }

     For other `UDF_ARGS' member values that are arrays, array
     references are zero-based. That is, refer to array members using
     index values from 0 to `args->arg_count' - 1.

   * `enum Item_result *arg_type'

     A pointer to an array containing the types for each argument. The
     possible type values are `STRING_RESULT', `INT_RESULT',
     `REAL_RESULT', and `DECIMAL_RESULT'.

     To make sure that arguments are of a given type and return an
     error if they are not, check the `arg_type' array in the
     initialization function. For example:

          if (args->arg_type[0] != STRING_RESULT ||
              args->arg_type[1] != INT_RESULT)
          {
              strcpy(message,"XXX() requires a string and an integer");
              return 1;
          }

     Arguments of type `DECIMAL_RESULT' are passed as strings, so you
     should handle them the same way as `STRING_RESULT' values.

     As an alternative to requiring your function's arguments to be of
     particular types, you can use the initialization function to set
     the `arg_type' elements to the types you want. This causes MySQL
     to coerce arguments to those types for each call to `xxx()'. For
     example, to specify that the first two arguments should be coerced
     to string and integer, respectively, do this in `xxx_init()':

          args->arg_type[0] = STRING_RESULT;
          args->arg_type[1] = INT_RESULT;

     Exact-value decimal arguments such as `1.3' or *Note `DECIMAL':
     numeric-types. column values are passed with a type of
     `DECIMAL_RESULT'.  However, the values are passed as strings. If
     you want to receive a number, use the initialization function to
     specify that the argument should be coerced to a `REAL_RESULT'
     value:

          args->arg_type[2] = REAL_RESULT;

   * `char **args'

     `args->args' communicates information to the initialization
     function about the general nature of the arguments passed to your
     function. For a constant argument `i', `args->args[i]' points to
     the argument value. (See below for instructions on how to access
     the value properly.) For a non-constant argument, `args->args[i]'
     is `0'. A constant argument is an expression that uses only
     constants, such as `3' or `4*7-2' or `SIN(3.14)'. A non-constant
     argument is an expression that refers to values that may change
     from row to row, such as column names or functions that are called
     with non-constant arguments.

     For each invocation of the main function, `args->args' contains
     the actual arguments that are passed for the row currently being
     processed.

     If argument `i' represents `NULL', `args->args[i]' is a null
     pointer (0).  If the argument is not `NULL', functions can refer
     to it as follows:

        * An argument of type `STRING_RESULT' is given as a string
          pointer plus a length, to allow handling of binary data or
          data of arbitrary length.  The string contents are available
          as `args->args[i]' and the string length is
          `args->lengths[i]'. Do not assume that the string is
          null-terminated.

        * For an argument of type `INT_RESULT', you must cast
          `args->args[i]' to a `long long' value:

               long long int_val;
               int_val = *((long long*) args->args[i]);

        * For an argument of type `REAL_RESULT', you must cast
          `args->args[i]' to a `double' value:

               double    real_val;
               real_val = *((double*) args->args[i]);

        * For an argument of type `DECIMAL_RESULT', the value is passed
          as a string and should be handled like a `STRING_RESULT'
          value.

        * `ROW_RESULT' arguments are not implemented.

   * `unsigned long *lengths'

     For the initialization function, the `lengths' array indicates the
     maximum string length for each argument. You should not change
     these. For each invocation of the main function, `lengths'
     contains the actual lengths of any string arguments that are
     passed for the row currently being processed. For arguments of
     types `INT_RESULT' or `REAL_RESULT', `lengths' still contains the
     maximum length of the argument (as for the initialization
     function).

   * `char *maybe_null'

     For the initialization function, the `maybe_null' array indicates
     for each argument whether the argument value might be null (0 if
     no, 1 if yes).

   * `char **attributes'

     `args->attributes' communicates information information about the
     names of the UDF arguments. For argument `i', the attribute name
     is available as a string in `args->attributes[i]' and the
     attribute length is `args->attribute_lengths[i]'. Do not assume
     that the string is null-terminated.

     By default, the name of a UDF argument is the text of the
     expression used to specify the argument. For UDFs, an argument may
     also have an optional `[AS] ALIAS_NAME' clause, in which case the
     argument name is ALIAS_NAME. The `attributes' value for each
     argument thus depends on whether an alias was given.

     Suppose that a UDF `my_udf()' is invoked as follows:

          SELECT my_udf(expr1, expr2 AS alias1, expr3 alias2);

     In this case, the `attributes' and `attribute_lengths' arrays will
     have these values:

          args->attributes[0] = "expr1"
          args->attribute_lengths[0] = 5

          args->attributes[1] = "alias1"
          args->attribute_lengths[1] = 6

          args->attributes[2] = "alias2"
          args->attribute_lengths[2] = 6

   * `unsigned long *attribute_lengths'

     The `attribute_lengths' array indicates the length of each
     argument name.


File: manual.info,  Node: udf-return-values,  Next: udf-compiling,  Prev: udf-arguments,  Up: adding-udf

21.3.2.4 UDF Return Values and Error Handling
.............................................

The initialization function should return `0' if no error occurred and
`1' otherwise. If an error occurs, `xxx_init()' should store a
null-terminated error message in the `message' parameter. The message
is returned to the client. The message buffer is `MYSQL_ERRMSG_SIZE'
characters long, but you should try to keep the message to less than 80
characters so that it fits the width of a standard terminal screen.

The return value of the main function `xxx()' is the function value,
for `long long' and `double' functions. A string function should return
a pointer to the result and set `*length' to the length (in bytes) of
the return value. For example:

     memcpy(result, "result string", 13);
     *length = 13;

MySQL passes a buffer to the `xxx()' function via the `result'
parameter. This buffer is sufficiently long to hold 255 characters,
which can be multi-byte characters. The `xxx()' function can store the
result in this buffer if it fits, in which case the return value should
be a pointer to the buffer. If the function stores the result in a
different buffer, it should return a pointer to that buffer.

If your string function does not use the supplied buffer (for example,
if it needs to return a string longer than 255 characters), you must
allocate the space for your own buffer with `malloc()' in your
`xxx_init()' function or your `xxx()' function and free it in your
`xxx_deinit()' function. You can store the allocated memory in the
`ptr' slot in the `UDF_INIT' structure for reuse by future `xxx()'
calls. See *Note udf-calling::.

To indicate a return value of `NULL' in the main function, set
`*is_null' to `1':

     *is_null = 1;

To indicate an error return in the main function, set `*error' to `1':

     *error = 1;

If `xxx()' sets `*error' to `1' for any row, the function value is
`NULL' for the current row and for any subsequent rows processed by the
statement in which `XXX()' was invoked.  (`xxx()' is not even called
for subsequent rows.)


File: manual.info,  Node: udf-compiling,  Next: udf-security,  Prev: udf-return-values,  Up: adding-udf

21.3.2.5 Compiling and Installing User-Defined Functions
........................................................

Files implementing UDFs must be compiled and installed on the host
where the server runs. This process is described below for the example
UDF file `sql/udf_example.c' that is included in the MySQL source
distribution.

The immediately following instructions are for Unix.  Instructions for
Windows are given later in this section.

The `udf_example.c' file contains the following functions:

   * `metaphon()' returns a metaphon string of the string argument.
     This is something like a soundex string, but it is more tuned for
     English.

   * `myfunc_double()' returns the sum of the ASCII values of the
     characters in its arguments, divided by the sum of the length of
     its arguments.

   * `myfunc_int()' returns the sum of the length of its arguments.

   * `sequence([const int])' returns a sequence starting from the given
     number or 1 if no number has been given.

   * `lookup()' returns the IP number for a host name.

   * `reverse_lookup()' returns the host name for an IP number. The
     function may be called either with a single string argument of the
     form `'xxx.xxx.xxx.xxx'' or with four numbers.

A dynamically loadable file should be compiled as a sharable object
file, using a command something like this:

     shell> gcc -shared -o udf_example.so udf_example.c

If you are using `gcc' with `configure' and `libtool' (which is how
MySQL is configured), you should be able to create `udf_example.so'
with a simpler command:

     shell> make udf_example.la

After you compile a shared object containing UDFs, you must install it
and tell MySQL about it. Compiling a shared object from `udf_example.c'
using `gcc' directly produces a file named `udf_example.so'. Compiling
the shared object using `make' produces a file named something like
`udf_example.so.0.0.0' in the `.libs' directory (the exact name may
vary from platform to platform). Copy the shared object to the server's
plugin directory and name it `udf_example.so'. This directory is given
by the value of the `plugin_dir' system variable.

On some systems, the `ldconfig' program that configures the dynamic
linker does not recognize a shared object unless its name begins with
`lib'. In this case you should rename a file such as `udf_example.so' to
`libudf_example.so'.

On Windows, you can compile user-defined functions by using the
following procedure:

  1. You need to obtain the Bazaar source repository for MySQL 6.0. See
     *Note installing-source-tree::.

  2. You must obtain the CMake build utility from
     `http://www.cmake.org'. (Version 2.4.2 or later is required).

  3. In the source repository, look in the `sql' directory. There are
     files named `udf_example.def' `udf_example.c' there. Copy both
     files from this directory to your working directory.

  4. Create a CMake `makefile' (`CMakeLists.txt') with these contents:

          PROJECT(udf_example)

          # Path for MySQL include directory
          INCLUDE_DIRECTORIES("c:/mysql/include")

          ADD_DEFINITIONS("-DHAVE_DLOPEN")
          ADD_LIBRARY(udf_example MODULE udf_example.c udf_example.def)
          TARGET_LINK_LIBRARIES(udf_example wsock32)

  5. Create the VC project and solution files:

          cmake -G "<Generator>"

     Invoking `cmake --help' shows you a list of valid Generators.

  6. Create `udf_example.dll':

          devenv udf_example.sln /build Release

After the shared object file has been installed, notify *Note `mysqld':
mysqld. about the new functions with these statements:

     mysql> CREATE FUNCTION metaphon RETURNS STRING SONAME 'udf_example.dll';
     mysql> CREATE FUNCTION myfunc_double RETURNS REAL SONAME 'udf_example.dll';
     mysql> CREATE FUNCTION myfunc_int RETURNS INTEGER SONAME 'udf_example.dll';
     mysql> CREATE FUNCTION sequence RETURNS INTEGER SONAME 'udf_example.dll';
     mysql> CREATE FUNCTION lookup RETURNS STRING SONAME 'udf_example.dll';
     mysql> CREATE FUNCTION reverse_lookup
         ->        RETURNS STRING SONAME 'udf_example.dll';
     mysql> CREATE AGGREGATE FUNCTION avgcost
         ->        RETURNS REAL SONAME 'udf_example.dll';

Functions can be deleted using *Note `DROP FUNCTION': drop-function.:

     mysql> DROP FUNCTION metaphon;
     mysql> DROP FUNCTION myfunc_double;
     mysql> DROP FUNCTION myfunc_int;
     mysql> DROP FUNCTION sequence;
     mysql> DROP FUNCTION lookup;
     mysql> DROP FUNCTION reverse_lookup;
     mysql> DROP FUNCTION avgcost;

The *Note `CREATE FUNCTION': create-function. and *Note `DROP
FUNCTION': drop-function. statements update the `func' system table in
the `mysql' database. The function's name, type and shared library name
are saved in the table. You must have the `INSERT' and `DELETE'
privileges for the `mysql' database to create and drop functions.

You should not use *Note `CREATE FUNCTION': create-function. to add a
function that has previously been created. If you need to reinstall a
function, you should remove it with *Note `DROP FUNCTION':
drop-function.  and then reinstall it with *Note `CREATE FUNCTION':
create-function. You would need to do this, for example, if you
recompile a new version of your function, so that *Note `mysqld':
mysqld. gets the new version. Otherwise, the server continues to use
the old version.

An active function is one that has been loaded with *Note `CREATE
FUNCTION': create-function. and not removed with *Note `DROP FUNCTION':
drop-function. All active functions are reloaded each time the server
starts, unless you start *Note `mysqld': mysqld. with the
`--skip-grant-tables' option. In this case, UDF initialization is
skipped and UDFs are unavailable.

If the new function will be referred to in statements that will be
replicated to slave servers, you must ensure that every slave server
also has the function available. Otherwise, replication will fail on
the slaves when they attempt to invoke the function.


File: manual.info,  Node: udf-security,  Prev: udf-compiling,  Up: adding-udf

21.3.2.6 User-Defined Function Security Precautions
...................................................

MySQL takes the following measures to prevent misuse of user-defined
functions.

You must have the `INSERT' privilege to be able to use *Note `CREATE
FUNCTION': create-function. and the `DELETE' privilege to be able to
use *Note `DROP FUNCTION': drop-function. This is necessary because
these statements add and delete rows from the `mysql.func' table.

UDFs should have at least one symbol defined in addition to the `xxx'
symbol that corresponds to the main `xxx()' function. These auxiliary
symbols correspond to the `xxx_init()', `xxx_deinit()', `xxx_reset()',
`xxx_clear()', and `xxx_add()' functions.  *Note `mysqld': mysqld. also
supports an `--allow-suspicious-udfs' option that controls whether UDFs
that have only an `xxx' symbol can be loaded. By default, the option is
off, to prevent attempts at loading functions from shared object files
other than those containing legitimate UDFs. If you have older UDFs
that contain only the `xxx' symbol and that cannot be recompiled to
include an auxiliary symbol, it may be necessary to specify the
`--allow-suspicious-udfs' option. Otherwise, you should avoid enabling
this capability.

UDF object files cannot be placed in arbitrary directories.  They must
be located in the server's plugin directory. This directory is given by
the value of the `plugin_dir' system variable.


File: manual.info,  Node: adding-native-function,  Prev: adding-udf,  Up: adding-functions

21.3.3 Adding a New Native Function
-----------------------------------

To add a new native MySQL function, use the procedure described here,
which requires that you use a source distribution. You cannot add
native functions to a binary distribution because it is necessary to
modify MySQL source code and compile MySQL from the modified source. If
you migrate to another version of MySQL (for example, when a new
version is released), you must repeat the procedure with the new
version.

If the new native function will be referred to in statements that will
be replicated to slave servers, you must ensure that every slave server
also has the function available. Otherwise, replication will fail on
the slaves when they attempt to invoke the function.

To add a new native function, follow these steps to modify source files
in the `sql' directory:

  1. Create a subclass for the function in `item_create.cc':

        * If the function takes a fixed number of arguments, create a
          subclass of `Create_func_arg0', `Create_func_arg1',
          `Create_func_arg2', or `Create_func_arg3', respectively,
          depending on whether the function takes zero, one, two, or
          three arguments. For examples, see the `Create_func_uuid',
          `Create_func_abs', `Create_func_pow', and `Create_func_lpad'
          classes.

        * If the function takes a variable number of arguments, create
          a subclass of `Create_native_func'. For an example, see
          `Create_func_concat'.

  2. To provide a name by which the function can be referred to in SQL
     statements, register the name in `item_create.cc' by adding a line
     to this array:

          static Native_func_registry func_array[]

     You can register several names for the same function. For example,
     see the lines for `"LCASE"' and `"LOWER"', which are aliases for
     `Create_func_lcase'.

  3. In `item_func.h', declare a class inheriting from `Item_num_func'
     or `Item_str_func', depending on whether your function returns a
     number or a string.

  4. In `item_func.cc', add one of the following declarations,
     depending on whether you are defining a numeric or string function:

          double   Item_func_newname::val()
          longlong Item_func_newname::val_int()
          String  *Item_func_newname::Str(String *str)

     If you inherit your object from any of the standard items (like
     `Item_num_func'), you probably only have to define one of these
     functions and let the parent object take care of the other
     functions. For example, the `Item_str_func' class defines a
     `val()' function that executes `atof()' on the value returned by
     `::str()'.

  5. If the function is non-deterministic, include the following
     statement in the item constructor to indicate that function
     results should not be cached:

          current_thd->lex->safe_to_cache_query=0;

     A function is non-deterministic if, given fixed values for its
     arguments, it can return different results for different
     invocations.

  6. You should probably also define the following object function:

          void Item_func_newname::fix_length_and_dec()

     This function should at least calculate `max_length' based on the
     given arguments.  `max_length' is the maximum number of characters
     the function may return. This function should also set `maybe_null
     = 0' if the main function can't return a `NULL' value. The
     function can check whether any of the function arguments can
     return `NULL' by checking the arguments' `maybe_null' variable.
     Look at `Item_func_mod::fix_length_and_dec' for a typical example
     of how to do this.

All functions must be thread-safe. In other words, do not use any
global or static variables in the functions without protecting them
with mutexes.

If you want to return `NULL' from `::val()', `::val_int()', or
`::str()', you should set `null_value' to 1 and return 0.

For `::str()' object functions, there are additional considerations to
be aware of:

   * The `String *str' argument provides a string buffer that may be
     used to hold the result. (For more information about the `String'
     type, take a look at the `sql_string.h' file.)

   * The `::str()' function should return the string that holds the
     result, or `(char*) 0' if the result is `NULL'.

   * All current string functions try to avoid allocating any memory
     unless absolutely necessary!


File: manual.info,  Node: adding-procedures,  Next: porting,  Prev: adding-functions,  Up: extending-mysql

21.4 Adding New Procedures to MySQL
===================================

* Menu:

* procedure-analyse::            `PROCEDURE ANALYSE'
* writing-a-procedure::          Writing a Procedure

In MySQL, you can define a procedure in C++ that can access and modify
the data in a query before it is sent to the client. The modification
can be done on a row-by-row or `GROUP BY' level.

We have created an example procedure to show you what can be done.

Additionally, we recommend that you take a look at `mylua'. With this
you can use the LUA language to load a procedure at runtime into *Note
`mysqld': mysqld.


File: manual.info,  Node: procedure-analyse,  Next: writing-a-procedure,  Prev: adding-procedures,  Up: adding-procedures

21.4.1 `PROCEDURE ANALYSE'
--------------------------

`analyse([MAX_ELEMENTS[,MAX_MEMORY]])'

This procedure is defined in the `sql/sql_analyse.cc' file. It examines
the result from a query and returns an analysis of the results that
suggests optimal data types for each column. To obtain this analysis,
append `PROCEDURE ANALYSE' to the end of a *Note `SELECT': select.
statement:

     SELECT ... FROM ... WHERE ... PROCEDURE ANALYSE([MAX_ELEMENTS,[MAX_MEMORY]])

For example:

     SELECT col1, col2 FROM table1 PROCEDURE ANALYSE(10, 2000);

The results show some statistics for the values returned by the query,
and propose an optimal data type for the columns. This can be helpful
for checking your existing tables, or after importing new data. You may
need to try different settings for the arguments so that `PROCEDURE
ANALYSE()' does not suggest the *Note `ENUM': enum. data type when it
is not appropriate.

The arguments are optional and are used as follows:

   * MAX_ELEMENTS (default 256) is the maximum number of distinct
     values that `analyse' notices per column. This is used by
     `analyse' to check whether the optimal data type should be of type
     *Note `ENUM': enum.; if there are more than MAX_ELEMENTS distinct
     values, then *Note `ENUM': enum. is not a suggested type.

   * MAX_MEMORY (default 8192) is the maximum amount of memory that
     `analyse' should allocate per column while trying to find all
     distinct values.


File: manual.info,  Node: writing-a-procedure,  Prev: procedure-analyse,  Up: adding-procedures

21.4.2 Writing a Procedure
--------------------------

For the moment, the only documentation for this is the source.

You can find all information about procedures by examining the
following files:

   * `sql/sql_analyse.cc'

   * `sql/procedure.h'

   * `sql/procedure.cc'

   * `sql/sql_select.cc'


File: manual.info,  Node: porting,  Prev: adding-procedures,  Up: extending-mysql

21.5 Debugging and Porting MySQL
================================

* Menu:

* debugging-server::             Debugging a MySQL Server
* debugging-client::             Debugging a MySQL Client
* the-dbug-package::             The DBUG Package
* rts-threads::                  Comments about RTS Threads
* thread-packages::              Differences Between Thread Packages

This appendix helps you port MySQL to other operating systems. Do check
the list of currently supported operating systems first. See *Note
which-os::. If you have created a new port of MySQL, please let us know
so that we can list it here and on our Web site
(`http://www.mysql.com/'), recommending it to other users.

Note: If you create a new port of MySQL, you are free to copy and
distribute it under the GPL license, but it does not make you a
copyright holder of MySQL.

A working POSIX thread library is needed for the server. On Solaris 2.5
we use Sun PThreads (the native thread support in 2.4 and earlier
versions is not good enough), on Linux we use LinuxThreads by Xavier
Leroy, <Xavier.Leroy@inria.fr>.

The hard part of porting to a new Unix variant without good native
thread support is probably to port MIT-pthreads. See
`mit-pthreads/README' and Programming POSIX Threads
(`http://www.humanfactor.com/pthreads/').

Up to MySQL 4.0.2, the MySQL distribution included a patched version of
Chris Provenzano's Pthreads from MIT (see the MIT Pthreads Web page at
`http://www.mit.edu/afs/sipb/project/pthreads/' and a programming
introduction at `http://www.mit.edu:8001/people/proven/IAP_2000/').
These can be used for some operating systems that do not have POSIX
threads. See *Note mit-pthreads::.

It is also possible to use another user level thread package named FSU
Pthreads (see `http://moss.csc.ncsu.edu/~mueller/pthreads/'). This
implementation is being used for the SCO port.

See the `thr_lock.c' and `thr_alarm.c' programs in the `mysys'
directory for some tests/examples of these problems.

Both the server and the client need a working C++ compiler. We use
`gcc' on many platforms. Other compilers that are known to work are
SPARCworks, Sun Forte, Irix `cc', HP-UX `aCC', IBM AIX `xlC_r'), Intel
`ecc/icc' and Compaq `cxx').

To compile only the client use `./configure --without-server'.

There is currently no support for only compiling the server, nor is it
likely to be added unless someone has a good reason for it.

If you want/need to change any `Makefile' or the configure script you
also need GNU Automake and Autoconf. See *Note installing-source-tree::.

All steps needed to remake everything from the most basic files.

     /bin/rm */.deps/*.P
     /bin/rm -f config.cache
     aclocal
     autoheader
     aclocal
     automake
     autoconf
     ./configure --with-debug=full --prefix='your installation directory'

     # The makefiles generated above need GNU make 3.75 or newer.
     # (called gmake below)
     gmake clean all install init-db

If you run into problems with a new port, you may have to do some
debugging of MySQL! See *Note debugging-server::.

*Note*:

Before you start debugging *Note `mysqld': mysqld, first get the test
programs `mysys/thr_alarm' and `mysys/thr_lock' to work. This ensures
that your thread installation has even a remote chance to work!


File: manual.info,  Node: debugging-server,  Next: debugging-client,  Prev: porting,  Up: porting

21.5.1 Debugging a MySQL Server
-------------------------------

* Menu:

* compiling-for-debugging::      Compiling MySQL for Debugging
* making-trace-files::           Creating Trace Files
* making-windows-dumps::         Using `pdb' to create a Windows crashdump
* using-gdb-on-mysqld::          Debugging `mysqld' under `gdb'
* using-stack-trace::            Using a Stack Trace
* using-log-files::              Using Server Logs to Find Causes of Errors in `mysqld'
* reproducible-test-case::       Making a Test Case If You Experience Table Corruption

If you are using some functionality that is very new in MySQL, you can
try to run *Note `mysqld': mysqld. with the `--skip-new' (which
disables all new, potentially unsafe functionality) or with
`--safe-mode' which disables a lot of optimization that may cause
problems. See *Note crashing::.

If *Note `mysqld': mysqld. doesn't want to start, you should verify
that you don't have any `my.cnf' files that interfere with your setup!
You can check your `my.cnf' arguments with *Note `mysqld
--print-defaults': mysqld. and avoid using them by starting with *Note
`mysqld --no-defaults ...': mysqld.

If *Note `mysqld': mysqld. starts to eat up CPU or memory or if it
`hangs,' you can use *Note `mysqladmin processlist status': mysqladmin.
to find out if someone is executing a query that takes a long time. It
may be a good idea to run *Note `mysqladmin -i10 processlist status':
mysqladmin. in some window if you are experiencing performance problems
or problems when new clients can't connect.

The command *Note `mysqladmin debug': mysqladmin. dumps some
information about locks in use, used memory and query usage to the
MySQL log file. This may help solve some problems. This command also
provides some useful information even if you haven't compiled MySQL for
debugging!

If the problem is that some tables are getting slower and slower you
should try to optimize the table with *Note `OPTIMIZE TABLE':
optimize-table. or *Note `myisamchk': myisamchk. See *Note
server-administration::. You should also check the slow queries with
*Note `EXPLAIN': explain.

You should also read the OS-specific section in this manual for
problems that may be unique to your environment. See *Note
operating-system-specific-notes::.


File: manual.info,  Node: compiling-for-debugging,  Next: making-trace-files,  Prev: debugging-server,  Up: debugging-server

21.5.1.1 Compiling MySQL for Debugging
......................................

If you have some very specific problem, you can always try to debug
MySQL. To do this you must configure MySQL with the `--with-debug' or
the `--with-debug=full' option.  You can check whether MySQL was
compiled with debugging by doing: *Note `mysqld --help': mysqld. If the
`--debug' flag is listed with the options then you have debugging
enabled. *Note `mysqladmin ver': mysqladmin. also lists the *Note
`mysqld': mysqld. version as *Note `mysql ... --debug': mysql. in this
case.

If you are using `gcc', the recommended `configure' line is:

     CC=gcc CFLAGS="-O2" CXX=gcc CXXFLAGS="-O2 -felide-constructors \
        -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql \
        --with-debug --with-extra-charsets=complex

This avoids problems with the `libstdc++' library and with C++
exceptions (many compilers have problems with C++ exceptions in
threaded code) and compile a MySQL version with support for all
character sets.

If you suspect a memory overrun error, you can configure MySQL with
`--with-debug=full', which installs a memory allocation (`SAFEMALLOC')
checker. However, running with `SAFEMALLOC' is quite slow, so if you get
performance problems you should start *Note `mysqld': mysqld. with the
`--skip-safemalloc' option. This disables the memory overrun checks for
each call to `malloc()' and `free()'.

If *Note `mysqld': mysqld. stops crashing when you compile it with
`--with-debug', you probably have found a compiler bug or a timing bug
within MySQL. In this case, you can try to add `-g' to the `CFLAGS' and
`CXXFLAGS' variables above and not use `--with-debug'. If *Note
`mysqld': mysqld. dies, you can at least attach to it with `gdb' or use
`gdb' on the core file to find out what happened.

When you configure MySQL for debugging you automatically enable a lot
of extra safety check functions that monitor the health of *Note
`mysqld': mysqld. If they find something `unexpected,' an entry is
written to `stderr', which *Note `mysqld_safe': mysqld-safe. directs to
the error log! This also means that if you are having some unexpected
problems with MySQL and are using a source distribution, the first
thing you should do is to configure MySQL for debugging! (The second
thing is to send mail to a MySQL mailing list and ask for help. See
*Note mailing-lists::. If you believe that you have found a bug, please
use the instructions at *Note bug-reports::.

In the Windows MySQL distribution, `mysqld.exe' is by default compiled
with support for trace files.


File: manual.info,  Node: making-trace-files,  Next: making-windows-dumps,  Prev: compiling-for-debugging,  Up: debugging-server

21.5.1.2 Creating Trace Files
.............................

If the *Note `mysqld': mysqld. server doesn't start or if you can cause
it to crash quickly, you can try to create a trace file to find the
problem.

To do this, you must have a *Note `mysqld': mysqld. that has been
compiled with debugging support. You can check this by executing
`mysqld -V'. If the version number ends with `-debug', it is compiled
with support for trace files. (On Windows, the debugging server is
named *Note `mysqld-debug': mysqld. rather than *Note `mysqld': mysqld.
as of MySQL 4.1.)

Start the *Note `mysqld': mysqld. server with a trace log in
`/tmp/mysqld.trace' on Unix or `C:\mysqld.trace' on Windows:

     shell> mysqld --debug

On Windows, you should also use the `--standalone' flag to not start
*Note `mysqld': mysqld. as a service. In a console window, use this
command:

     C:\> mysqld-debug --debug --standalone

After this, you can use the `mysql.exe' command-line tool in a second
console window to reproduce the problem. You can stop the *Note
`mysqld': mysqld. server with *Note `mysqladmin shutdown': mysqladmin.

Note that the trace file become *very big*! If you want to generate a
smaller trace file, you can use debugging options something like this:

*Note `mysqld
--debug=d,info,error,query,general,where:O,/tmp/mysqld.trace': mysqld.

This only prints information with the most interesting tags to the
trace file.

If you make a bug report about this, please only send the lines from
the trace file to the appropriate mailing list where something seems to
go wrong! If you can't locate the wrong place, you can ftp the trace
file, together with a full bug report, to
`ftp://ftp.mysql.com/pub/mysql/upload/' so that a MySQL developer can
take a look at it.

The trace file is made with the *DBUG* package by Fred Fish.  See *Note
the-dbug-package::.


File: manual.info,  Node: making-windows-dumps,  Next: using-gdb-on-mysqld,  Prev: making-trace-files,  Up: debugging-server

21.5.1.3 Using `pdb' to create a Windows crashdump
..................................................

Program Database files (extension `pdb') are included in the Noinstall
distribution of MySQL. These files provide information for debugging
your MySQL installation in the event of a problem.

The PDB file contains more detailed information about `mysqld' and
other tools that enables more detailed trace and dump files to be
created. You can use these with Dr Watson, `WinDbg' and Visual Studio to
debug *Note `mysqld': mysqld.

For more information on PDB files, see Microsoft Knowledge Base Article
121366 (http://support.microsoft.com/kb/121366/). For more information
on the debugging options available, see Debugging Tools for Windows
(http://www.microsoft.com/whdc/devtools/debugging/default.mspx).

Dr Watson is installed with all Windows distributions, but if you have
installed Windows development tools, Dr Watson may have been replaced
with WinDbg, the debugger included with Visual Studio, or the debugging
tools provided with Borland or Delphi.

To generate a crash file using Dr Watson, follow these steps:

  1. Start Dr Watson by running `drwtsn32.exe' interactively using the
     `-i' option:

          C:\> drwtsn32 -i

  2. Set the `Log File Path' to the directory where you want to store
     trace files.

  3. Make sure `Dump All Thread Contexts' and `Append To Existing Log
     File'.

  4. Uncheck `Dump Sumbol Table', `Visual Notification', `Sound
     Notification' and `Create Crash Dump File'.

  5. Set the `Number of Instructions' to a suitable value to capture
     enough calls in the stacktrace.  A value of at 25 should be enough.

*Caution*:

Note that the file generated can be very large.

The dump file generated can be used within Microsoft Visual Studio to
debug the application and determine what caused the problem.


File: manual.info,  Node: using-gdb-on-mysqld,  Next: using-stack-trace,  Prev: making-windows-dumps,  Up: debugging-server

21.5.1.4 Debugging `mysqld' under `gdb'
.......................................

On most systems you can also start *Note `mysqld': mysqld.  from `gdb'
to get more information if *Note `mysqld': mysqld. crashes.

With some older `gdb' versions on Linux you must use `run --one-thread'
if you want to be able to debug *Note `mysqld': mysqld. threads. In
this case, you can only have one thread active at a time. We recommend
you to upgrade to gdb 5.1 ASAP as thread debugging works much better
with this version!

NPTL threads (the new thread library on Linux) may cause problems while
running *Note `mysqld': mysqld. under `gdb'. Some symptoms are:

   * *Note `mysqld': mysqld. hangs during startup (before it writes
     `ready for connections').

   * *Note `mysqld': mysqld. crashes during a `pthread_mutex_lock()' or
     `pthread_mutex_unlock()' call.

In this case, you should set the following environment variable in the
shell before starting `gdb':

     LD_ASSUME_KERNEL=2.4.1
     export LD_ASSUME_KERNEL

When running *Note `mysqld': mysqld. under `gdb', you should disable
the stack trace with `--skip-stack-trace' to be able to catch segfaults
within `gdb'.

In MySQL 4.0.14 and above you should use the `--gdb' option to *Note
`mysqld': mysqld. This installs an interrupt handler for `SIGINT'
(needed to stop *Note `mysqld': mysqld. with `^C' to set breakpoints)
and disable stack tracing and core file handling.

It is very hard to debug MySQL under `gdb' if you do a lot of new
connections the whole time as `gdb' doesn't free the memory for old
threads. You can avoid this problem by starting *Note `mysqld': mysqld.
with `thread_cache_size' set to a value equal to `max_connections' + 1.
In most cases just using `--thread_cache_size=5'' helps a lot!

If you want to get a core dump on Linux if *Note `mysqld': mysqld. dies
with a SIGSEGV signal, you can start *Note `mysqld': mysqld. with the
`--core-file' option. This core file can be used to make a backtrace
that may help you find out why *Note `mysqld': mysqld. died:

     shell> gdb mysqld core
     gdb>   backtrace full
     gdb>   quit

See *Note crashing::.

If you are using `gdb' 4.17.x or above on Linux, you should install a
`.gdb' file, with the following information, in your current directory:

     set print sevenbit off
     handle SIGUSR1 nostop noprint
     handle SIGUSR2 nostop noprint
     handle SIGWAITING nostop noprint
     handle SIGLWP nostop noprint
     handle SIGPIPE nostop
     handle SIGALRM nostop
     handle SIGHUP nostop
     handle SIGTERM nostop noprint

If you have problems debugging threads with `gdb', you should download
gdb 5.x and try this instead. The new `gdb' version has very improved
thread handling!

Here is an example how to debug mysqld:

     shell> gdb /usr/local/libexec/mysqld
     gdb> run
     ...
     backtrace full # Do this when mysqld crashes

Include the above output in a bug report, which you can file using the
instructions in *Note bug-reports::.

If *Note `mysqld': mysqld. hangs you can try to use some system tools
like `strace' or `/usr/proc/bin/pstack' to examine where *Note
`mysqld': mysqld. has hung.

     strace /tmp/log libexec/mysqld

If you are using the Perl `DBI' interface, you can turn on debugging
information by using the `trace' method or by setting the `DBI_TRACE'
environment variable.


File: manual.info,  Node: using-stack-trace,  Next: using-log-files,  Prev: using-gdb-on-mysqld,  Up: debugging-server

21.5.1.5 Using a Stack Trace
............................

On some operating systems, the error log contains a stack trace if
*Note `mysqld': mysqld. dies unexpectedly. You can use this to find out
where (and maybe why) *Note `mysqld': mysqld. died. See *Note
error-log::. To get a stack trace, you must not compile *Note `mysqld':
mysqld. with the `-fomit-frame-pointer' option to gcc. See *Note
compiling-for-debugging::.

A stack trace in the error log looks something like this:

     mysqld got signal 11;
     Attempting backtrace. You can use the following information
     to find out where mysqld died. If you see no messages after
     this, something went terribly wrong...

     stack_bottom = 0x41fd0110 thread_stack 0x40000
     mysqld(my_print_stacktrace+0x32)[0x9da402]
     mysqld(handle_segfault+0x28a)[0x6648e9]
     /lib/libpthread.so.0[0x7f1a5af000f0]
     /lib/libc.so.6(strcmp+0x2)[0x7f1a5a10f0f2]
     mysqld(_Z21check_change_passwordP3THDPKcS2_Pcj+0x7c)[0x7412cb]
     mysqld(_ZN16set_var_password5checkEP3THD+0xd0)[0x688354]
     mysqld(_Z17sql_set_variablesP3THDP4ListI12set_var_baseE+0x68)[0x688494]
     mysqld(_Z21mysql_execute_commandP3THD+0x41a0)[0x67a170]
     mysqld(_Z11mysql_parseP3THDPKcjPS2_+0x282)[0x67f0ad]
     mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0xbb7[0x67fdf8]
     mysqld(_Z10do_commandP3THD+0x24d)[0x6811b6]
     mysqld(handle_one_connection+0x11c)[0x66e05e]

If resolution of function names for the trace fails, the trace contains
less information:

     mysqld got signal 11;
     Attempting backtrace. You can use the following information
     to find out where mysqld died. If you see no messages after
     this, something went terribly wrong...

     stack_bottom = 0x41fd0110 thread_stack 0x40000
     [0x9da402]
     [0x6648e9]
     [0x7f1a5af000f0]
     [0x7f1a5a10f0f2]
     [0x7412cb]
     [0x688354]
     [0x688494]
     [0x67a170]
     [0x67f0ad]
     [0x67fdf8]
     [0x6811b6]
     [0x66e05e]

In the latter case, you can use the *Note `resolve_stack_dump':
resolve-stack-dump. utility to determine where *Note `mysqld': mysqld.
died by using the following procedure:

  1. Copy the numbers from the stack trace to a file, for example
     `mysqld.stack'. The numbers should not include the surrounding
     square brackets:

          0x9da402
          0x6648e9
          0x7f1a5af000f0
          0x7f1a5a10f0f2
          0x7412cb
          0x688354
          0x688494
          0x67a170
          0x67f0ad
          0x67fdf8
          0x6811b6
          0x66e05e

  2. Make a symbol file for the *Note `mysqld': mysqld.  server:

          shell> nm -n libexec/mysqld > /tmp/mysqld.sym

     If *Note `mysqld': mysqld. is not linked statically, use the
     following command instead:

          shell> nm -D -n libexec/mysqld > /tmp/mysqld.sym

     If you want to decode C++ symbols, use the `--demangle', if
     available, to `nm'. If your version of `nm' does not have this
     option, you will need to use the `c++filt' command after the stack
     dump has been produced to demangle the C++ names.

  3. Execute the following command:

          shell> resolve_stack_dump -s /tmp/mysqld.sym -n mysqld.stack

     If you were not able to include demangled C++ names in your symbol
     file, process the *Note `resolve_stack_dump': resolve-stack-dump.
     output using `c++filt':

          shell> resolve_stack_dump -s /tmp/mysqld.sym -n mysqld.stack | c++filt

     This prints out where *Note `mysqld': mysqld. died. If that does
     not help you find out why *Note `mysqld': mysqld. died, you should
     create a bug report and include the output from the preceding
     command with the bug report.

     However, in most cases it does not help us to have just a stack
     trace to find the reason for the problem. To be able to locate the
     bug or provide a workaround, in most cases we need to know the
     statement that killed *Note `mysqld': mysqld. and preferably a
     test case so that we can repeat the problem! See *Note
     bug-reports::.


File: manual.info,  Node: using-log-files,  Next: reproducible-test-case,  Prev: using-stack-trace,  Up: debugging-server

21.5.1.6 Using Server Logs to Find Causes of Errors in `mysqld'
...............................................................

Note that before starting *Note `mysqld': mysqld. with the general
query log enabled, you should check all your tables with *Note
`myisamchk': myisamchk. See *Note server-administration::.

If *Note `mysqld': mysqld. dies or hangs, you should start *Note
`mysqld': mysqld. with the general query log enabled.  See *Note
query-log::. When *Note `mysqld': mysqld. dies again, you can examine
the end of the log file for the query that killed *Note `mysqld':
mysqld.

If you use the default general query log file, the log is stored in the
database directory as `HOST_NAME.log' In most cases it is the last
query in the log file that killed *Note `mysqld': mysqld, but if
possible you should verify this by restarting *Note `mysqld': mysqld.
and executing the found query from the *Note `mysql': mysql.
command-line tools. If this works, you should also test all complicated
queries that didn't complete.

You can also try the command *Note `EXPLAIN': explain. on all *Note
`SELECT': select. statements that takes a long time to ensure that
*Note `mysqld': mysqld. is using indexes properly. See *Note explain::.

You can find the queries that take a long time to execute by starting
*Note `mysqld': mysqld. with the slow query log enabled. See *Note
slow-query-log::.

If you find the text `mysqld restarted' in the error log file (normally
named `hostname.err') you probably have found a query that causes *Note
`mysqld': mysqld. to fail. If this happens, you should check all your
tables with *Note `myisamchk': myisamchk. (see *Note
server-administration::), and test the queries in the MySQL log files
to see whether one fails. If you find such a query, try first upgrading
to the newest MySQL version.  If this doesn't help and you can't find
anything in the `mysql' mail archive, you should report the bug to a
MySQL mailing list. The mailing lists are described at
`http://lists.mysql.com/', which also has links to online list archives.

If you have started *Note `mysqld': mysqld. with `--myisam-recover',
MySQL automatically checks and tries to repair `MyISAM' tables if they
are marked as 'not closed properly' or 'crashed'. If this happens,
MySQL writes an entry in the `hostname.err' file `'Warning: Checking
table ...'' which is followed by `Warning: Repairing table' if the
table needs to be repaired. If you get a lot of these errors, without
*Note `mysqld': mysqld. having died unexpectedly just before, then
something is wrong and needs to be investigated further. See *Note
server-options::.

As of MySQL 6.0.4, when the server detects `MyISAM' table corruption,
it writes additional information to the error log, such as the name and
line number of the source file, and the list of threads accessing the
table. Example: `Got an error from thread_id=1, mi_dynrec.c:368 '. This
is useful information to include in bug reports.

It is not a good sign if *Note `mysqld': mysqld. did die unexpectedly,
but in this case, you should not investigate the `Checking table...'
messages, but instead try to find out why *Note `mysqld': mysqld. died.


File: manual.info,  Node: reproducible-test-case,  Prev: using-log-files,  Up: debugging-server

21.5.1.7 Making a Test Case If You Experience Table Corruption
..............................................................

If you get corrupted tables or if *Note `mysqld': mysqld.  always fails
after some update commands, you can test whether this bug is
reproducible by doing the following:

   * Take down the MySQL daemon (with *Note `mysqladmin shutdown':
     mysqladmin.).

   * Make a backup of the tables (to guard against the very unlikely
     case that the repair does something bad).

   * Check all tables with *Note `myisamchk -s database/*.MYI':
     myisamchk. Repair any wrong tables with *Note `myisamchk -r
     database/TABLE.MYI': myisamchk.

   * Make a second backup of the tables.

   * Remove (or move away) any old log files from the MySQL data
     directory if you need more space.

   * Start *Note `mysqld': mysqld. with the binary log enabled. If you
     want to find a query that crashes *Note `mysqld': mysqld, you
     should start the server with both the general query log enabled as
     well. See *Note query-log::, and *Note binary-log::.

   * When you have gotten a crashed table, stop the `mysqld server'.

   * Restore the backup.

   * Restart the *Note `mysqld': mysqld. server *without* the binary log
     enabled.

   * Re-execute the commands with *Note `mysqlbinlog binary-log-file |
     mysql': mysqlbinlog. The binary log is saved in the MySQL database
     directory with the name `hostname-bin.NNNNNN'.

   * If the tables are corrupted again or you can get *Note `mysqld':
     mysqld. to die with the above command, you have found reproducible
     bug that should be easy to fix! FTP the tables and the binary log
     to `ftp://ftp.mysql.com/pub/mysql/upload/' and report it in our
     bugs database using the instructions given in *Note bug-reports::.
     (Please note that the `/pub/mysql/upload/' FTP directory is not
     listable, so you'll not see what you've uploaded in your FTP
     client.) If you are a support customer, you can use the MySQL
     Customer Support Center `https://support.mysql.com/' to alert the
     MySQL team about the problem and have it fixed as soon as possible.

You can also use the script *Note `mysql_find_rows': mysql-find-rows.
to just execute some of the update statements if you want to narrow
down the problem.


File: manual.info,  Node: debugging-client,  Next: the-dbug-package,  Prev: debugging-server,  Up: porting

21.5.2 Debugging a MySQL Client
-------------------------------

To be able to debug a MySQL client with the integrated debug package,
you should configure MySQL with `--with-debug' or `--with-debug=full'.
See *Note configure-options::.

Before running a client, you should set the `MYSQL_DEBUG' environment
variable:

     shell> MYSQL_DEBUG=d:t:O,/tmp/client.trace
     shell> export MYSQL_DEBUG

This causes clients to generate a trace file in `/tmp/client.trace'.

If you have problems with your own client code, you should attempt to
connect to the server and run your query using a client that is known
to work. Do this by running *Note `mysql': mysql. in debugging mode
(assuming that you have compiled MySQL with debugging on):

     shell> mysql --debug=d:t:O,/tmp/client.trace

This provides useful information in case you mail a bug report.  See
*Note bug-reports::.

If your client crashes at some 'legal' looking code, you should check
that your `mysql.h' include file matches your MySQL library file. A
very common mistake is to use an old `mysql.h' file from an old MySQL
installation with new MySQL library.


File: manual.info,  Node: the-dbug-package,  Next: rts-threads,  Prev: debugging-client,  Up: porting

21.5.3 The DBUG Package
-----------------------

The MySQL server and most MySQL clients are compiled with the DBUG
package originally created by Fred Fish. When you have configured MySQL
for debugging, this package makes it possible to get a trace file of
what the program is debugging. See *Note making-trace-files::.

This section summaries the argument values that you can specify in
debug options on the command line for MySQL programs that have been
built with debugging support. For more information about programming
with the DBUG package, see the DBUG manual in the `dbug' directory of
MySQL source distributions. It is best to use a recent distribution to
get the most updated DBUG manual.

You use the debug package by invoking a program with the
`--debug="..."' or the `-#...' option.

Most MySQL programs have a default debug string that is used if you
don't specify an option to `--debug'. The default trace file is usually
`/tmp/program_name.trace' on Unix and `\program_name.trace' on Windows.

The debug control string is a sequence of colon-separated fields as
follows:

     <field_1>:<field_2>:...:<field_N>

Each field consists of a mandatory flag character followed by an
optional ``,'' and comma-separated list of modifiers:

     flag[,modifier,modifier,...,modifier]

The following table shows the currently recognized flag characters.

*Flag**Description*
`d'  Enable output from DBUG_<N> macros for the current state. May be
     followed by a list of keywords which selects output only for the
     DBUG macros with that keyword. An empty list of keywords implies
     output for all macros.
`D'  Delay after each debugger output line. The argument is the number of
     tenths of seconds to delay, subject to machine capabilities. For
     example, `-#D,20' specifies a delay of two seconds.
`f'  Limit debugging, tracing, and profiling to the list of named
     functions.  Note that a null list disables all functions. The
     appropriate `d' or `t' flags must still be given; this flag only
     limits their actions if they are enabled.
`F'  Identify the source file name for each line of debug or trace
     output.
`i'  Identify the process with the PID or thread ID for each line of
     debug or trace output.
`g'  Enable profiling. Create a file called `dbugmon.out' containing
     information that can be used to profile the program. May be
     followed by a list of keywords that select profiling only for the
     functions in that list. A null list implies that all functions are
     considered.
`L'  Identify the source file line number for each line of debug or trace
     output.
`n'  Print the current function nesting depth for each line of debug or
     trace output.
`N'  Number each line of debug output.
`o'  Redirect the debugger output stream to the specified file. The
     default output is `stderr'.
`O'  Like `o', but the file is really flushed between each write. When
     needed, the file is closed and reopened between each write.
`p'  Limit debugger actions to specified processes. A process must be
     identified with the `DBUG_PROCESS' macro and match one in the list
     for debugger actions to occur.
`P'  Print the current process name for each line of debug or trace
     output.
`r'  When pushing a new state, do not inherit the previous state's
     function nesting level. Useful when the output is to start at the
     left margin.
`S'  Do function `_sanity(_file_,_line_)' at each debugged function
     until `_sanity()' returns something that differs from 0. (Mostly
     used with `safemalloc' to find memory leaks)
`t'  Enable function call/exit trace lines. May be followed by a list
     (containing only one modifier) giving a numeric maximum trace
     level, beyond which no output occurs for either debugging or
     tracing macros. The default is a compile time option.

Some examples of debug control strings that might appear on a shell
command line (the `-#' is typically used to introduce a control string
to an application program) are:

     -#d:t
     -#d:f,main,subr1:F:L:t,20
     -#d,input,output,files:n
     -#d:t:i:O,\\mysqld.trace

In MySQL, common tags to print (with the `d' option) are `enter',
`exit', `error', `warning', `info', and `loop'.


File: manual.info,  Node: rts-threads,  Next: thread-packages,  Prev: the-dbug-package,  Up: porting

21.5.4 Comments about RTS Threads
---------------------------------

I have tried to use the RTS thread packages with MySQL but stumbled on
the following problems:

They use old versions of many POSIX calls and it is very tedious to
make wrappers for all functions. I am inclined to think that it would
be easier to change the thread libraries to the newest POSIX
specification.

Some wrappers are currently written. See `mysys/my_pthread.c' for more
info.

At least the following should be changed:

`pthread_get_specific' should use one argument.  `sigwait' should take
two arguments. A lot of functions (at least `pthread_cond_wait',
`pthread_cond_timedwait()') should return the error code on error. Now
they return -1 and set `errno'.

Another problem is that user-level threads use the `ALRM' signal and
this aborts a lot of functions (`read', `write', `open'...). MySQL
should do a retry on interrupt on all of these but it is not that easy
to verify it.

The biggest unsolved problem is the following:

To get thread-level alarms I changed `mysys/thr_alarm.c' to wait
between alarms with `pthread_cond_timedwait()', but this aborts with
error `EINTR'. I tried to debug the thread library as to why this
happens, but couldn't find any easy solution.

If someone wants to try MySQL with RTS threads I suggest the following:

   * Change functions MySQL uses from the thread library to POSIX. This
     shouldn't take that long.

   * Compile all libraries with the `-DHAVE_rts_threads'.

   * Compile `thr_alarm'.

   * If there are some small differences in the implementation, they
     may be fixed by changing `my_pthread.h' and `my_pthread.c'.

   * Run `thr_alarm'. If it runs without any `warning,' `error,' or
     aborted messages, you are on the right track. Here is a successful
     run on Solaris:

          Main thread: 1
          Thread 0 (5) started
          Thread: 5  Waiting
          process_alarm
          Thread 1 (6) started
          Thread: 6  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Slept for 1 (1) sec
          Thread: 6  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Slept for 2 (2) sec
          Thread: 6  Simulation of no alarm needed
          Thread: 6  Slept for 0 (3) sec
          Thread: 6  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Slept for 4 (4) sec
          Thread: 6  Waiting
          process_alarm
          thread_alarm
          Thread: 5  Slept for 10 (10) sec
          Thread: 5  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Slept for 5 (5) sec
          Thread: 6  Waiting
          process_alarm
          process_alarm

          ...
          thread_alarm
          Thread: 5  Slept for 0 (1) sec
          end


File: manual.info,  Node: thread-packages,  Prev: rts-threads,  Up: porting

21.5.5 Differences Between Thread Packages
------------------------------------------

MySQL is very dependent on the thread package used. So when choosing a
good platform for MySQL, the thread package is very important.

There are at least three types of thread packages:

   * User threads in a single process. Thread switching is managed with
     alarms and the threads library manages all non-thread-safe
     functions with locks. Read, write and select operations are
     usually managed with a thread-specific select that switches to
     another thread if the running threads have to wait for data. If
     the user thread packages are integrated in the standard libs
     (FreeBSD and BSDI threads) the thread package requires less
     overhead than thread packages that have to map all unsafe calls
     (MIT-pthreads, FSU Pthreads and RTS threads). In some environments
     (for example, SCO), all system calls are thread-safe so the
     mapping can be done very easily (FSU Pthreads on SCO). Downside:
     All mapped calls take a little time and it is quite tricky to be
     able to handle all situations. There are usually also some system
     calls that are not handled by the thread package (like
     MIT-pthreads and sockets). Thread scheduling isn't always optimal.

   * User threads in separate processes. Thread switching is done by
     the kernel and all data are shared between threads. The thread
     package manages the standard thread calls to allow sharing data
     between threads. LinuxThreads is using this method. Downside: Lots
     of processes. Thread creating is slow. If one thread dies the rest
     are usually left hanging and you must kill them all before
     restarting. Thread switching is somewhat expensive.

   * Kernel threads. Thread switching is handled by the thread library
     or the kernel and is very fast. Everything is done in one process,
     but on some systems, `ps' may show the different threads. If one
     thread aborts, the whole process aborts. Most system calls are
     thread-safe and should require very little overhead. Solaris,
     HP-UX, AIX and OSF/1 have kernel threads.

In some systems kernel threads are managed by integrating user level
threads in the system libraries. In such cases, the thread switching
can only be done by the thread library and the kernel isn't really
`thread aware.'


File: manual.info,  Node: faqs,  Next: error-handling,  Prev: extending-mysql,  Up: Top

Appendix A MySQL 6.0 Frequently Asked Questions
***********************************************

* Menu:

* faqs-general::                 MySQL 6.0 FAQ --- General
* faqs-storage-engines::         MySQL 6.0 FAQ --- Storage Engines
* faqs-sql-modes::               MySQL 6.0 FAQ --- Server SQL Mode
* faqs-stored-procs::            MySQL 6.0 FAQ --- Stored Procedures and Functions
* faqs-triggers::                MySQL 6.0 FAQ --- Triggers
* faqs-views::                   MySQL 6.0 FAQ --- Views
* faqs-information-schema::      MySQL 5.0 FAQ --- `INFORMATION_SCHEMA'
* faqs-migration::               MySQL 6.0 FAQ --- Migration
* faqs-security::                MySQL 6.0 FAQ --- Security
* faqs-mysql-cluster::           MySQL 6.0 FAQ --- MySQL Cluster
* faqs-cjk::                     MySQL 6.0 FAQ --- MySQL Chinese, Japanese, and Korean Character Sets
* faqs-connectors-apis::         MySQL 6.0 FAQ --- Connectors & APIs
* faqs-replication::             MySQL 6.0 FAQ --- Replication
* faqs-mysql-drbd-heartbeat::    MySQL 6.0 FAQ --- MySQL, DRBD, and Heartbeat


File: manual.info,  Node: faqs-general,  Next: faqs-storage-engines,  Prev: faqs,  Up: faqs

A.1 MySQL 6.0 FAQ -- General
============================

*Questions*
   * 22.1.1: Which version of MySQL is production-ready (GA)?

   * 22.1.2: Can MySQL 6.0 do subqueries?

   * 22.1.3: Can MySQL 6.0 perform multiple-table inserts, updates, and
     deletes?

   * 22.1.4: Does MySQL 6.0 have a Query Cache? Does it work on Server,
     Instance or Database?

   * 22.1.5: Does MySQL 6.0 have Sequences?

   * 22.1.6: Does MySQL 6.0 have a `NOW()' function with fractions of
     seconds?

   * 22.1.7: Does MySQL 6.0 work with multi-core processors?

   * 22.1.8: Is there a hot backup tool for MyISAM like InnoDB Hot
     Backup?

   * 22.1.9: Have there been there any improvements in error reporting
     when foreign keys fail? Does MySQL now report which column and
     reference failed?

   * 22.1.10: Can MySQL 6.0 perform ACID transactions?

*Questions and Answers* *22.1.1: ** Which version of MySQL is
production-ready (GA)?  *

Currently, both MySQL 5.0 and MySQL 5.1 are supported for production
use.

MySQL 5.0 achieved General Availability (GA) status with MySQL 5.0.15,
which was released for production use on 19 October 2005.

MySQL 5.1 achieved General Availability (GA) status with MySQL 5.1.30,
which was released for production use on 14 November 2008.

Development work on MySQL 6.0 has started; currently, MySQL 6.0 is in
alpha status.

*22.1.2: ** Can MySQL 6.0 do subqueries?  *

Yes. See *Note subqueries::.

*22.1.3: ** Can MySQL 6.0 perform multiple-table inserts, updates, and
deletes?  *

Yes. For the syntax required to perform multiple-table updates, see
*Note update::; for that required to perform multiple-table deletes, see
*Note delete::.

A multiple-table insert can be accomplished using a trigger whose `FOR
EACH ROW' clause contains multiple *Note `INSERT': insert. statements
within a `BEGIN ... END' block. See *Note triggers::.

*22.1.4: ** Does MySQL 6.0 have a Query Cache? Does it work on Server,
Instance or Database?  *

Yes. The query cache operates on the server level, caching complete
result sets matched with the original query string.  If an exactly
identical query is made (which often happens, particularly in web
applications), no parsing or execution is necessary; the result is sent
directly from the cache.  Various tuning options are available. See
*Note query-cache::.

*22.1.5: ** Does MySQL 6.0 have Sequences?  *

No. However, MySQL has an `AUTO_INCREMENT' system, which in MySQL 6.0
can also handle inserts in a multi-master replication setup. With the
`auto_increment_increment' and `auto_increment_offset' system
variables, you can set each server to generate auto-increment values
that don't conflict with other servers. The `auto_increment_increment'
value should be greater than the number of servers, and each server
should have a unique offset.

*22.1.6: ** Does MySQL 6.0 have a `NOW()' function with fractions of
seconds?  *

No. This is on the MySQL roadmap as a `rolling feature'. This means
that it is not a flagship feature, but will be implemented, development
time permitting. Specific customer demand may change this scheduling.

However, MySQL does parse time strings with a fractional component. See
*Note time::.

*22.1.7: ** Does MySQL 6.0 work with multi-core processors?  *

Yes. MySQL is fully multi-threaded, and will make use of multiple CPUs,
provided that the operating system supports them.

*22.1.8: ** Is there a hot backup tool for MyISAM like InnoDB Hot
Backup?  *

This is currently under development for a future MySQL release.

*22.1.9: ** Have there been there any improvements in error reporting
when foreign keys fail? Does MySQL now report which column and
reference failed?  *

The foreign key support in `InnoDB' has seen improvements in each major
version of MySQL. Foreign key support generic to all storage engines is
scheduled for MySQL 6.x; this should resolve any inadequacies in the
current storage engine specific implementation.

*22.1.10: ** Can MySQL 6.0 perform ACID transactions?  *

Yes. All current MySQL versions support transactions. The `InnoDB'
storage engine offers full ACID transactions with row-level locking,
multi-versioning, non-locking repeatable reads, and all four SQL
standard isolation levels.

The `NDB' storage engine supports the `READ COMMITTED' transaction
isolation level only.


File: manual.info,  Node: faqs-storage-engines,  Next: faqs-sql-modes,  Prev: faqs-general,  Up: faqs

A.2 MySQL 6.0 FAQ -- Storage Engines
====================================

*Questions*
   * 22.2.1: Where can I obtain complete documentation for MySQL storage
     engines and the pluggable storage engine architecture?

   * 22.2.2: Are there any new storage engines in MySQL 6.0?

   * 22.2.3: Have any storage engines been removed in MySQL 6.0?

   * 22.2.4: What are the unique benefits of the `ARCHIVE' storage
     engine?

   * 22.2.5: Do the new features in MySQL 6.0 apply to all storage
     engines?

*Questions and Answers* *22.2.1: ** Where can I obtain complete
documentation for MySQL storage engines and the pluggable storage
engine architecture?  *

See *Note storage-engines::. That chapter contains information about
all MySQL storage engines except for the `NDB' storage engine used for
MySQL Cluster; `NDB' is covered in MySQL Cluster NDB 6.X/7.X
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html).

MySQL Enterprise

For expert advice about the storage engine(s) most suitable to your
circumstances subscribe to the MySQL Enterprise Monitor. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*22.2.2: ** Are there any new storage engines in MySQL 6.0?  *

MySQL 6.0 introduces an alpha version of the new Falcon storage engine.

For information about the Falcon storage engine, see *Note se-falcon::.

There have also been significant improvements in existing storage
engines, in particular for the `NDB' storage engine that forms the
basis for MySQL Cluster.

*22.2.3: ** Have any storage engines been removed in MySQL 6.0?  *

Yes. MySQL 6.0 no longer supports the `BDB' storage engine. Any existing
`BDB' tables should be converted to another storage engine before
upgrading to MySQL 6.0.

*22.2.4: ** What are the unique benefits of the `ARCHIVE' storage
engine?  *

The `ARCHIVE' storage engine is ideally suited for storing large
amounts of data without indexes; it has a very small footprint, and
performs selects using table scans. See *Note archive-storage-engine::,
for details.

*22.2.5: ** Do the new features in MySQL 6.0 apply to all storage
engines?  *

The general new features such as views, stored procedures, triggers,
`INFORMATION_SCHEMA', precision math (*Note `DECIMAL': numeric-types.
column type), and the *Note `BIT': numeric-types. column type, apply to
all storage engines. There are also additions and changes for specific
storage engines.


File: manual.info,  Node: faqs-sql-modes,  Next: faqs-stored-procs,  Prev: faqs-storage-engines,  Up: faqs

A.3 MySQL 6.0 FAQ -- Server SQL Mode
====================================

*Questions*
   * 22.3.1: What are server SQL modes?

   * 22.3.2: How many server SQL modes are there?

   * 22.3.3: How do you determine the server SQL mode?

   * 22.3.4: Is the mode dependent on the database or connection?

   * 22.3.5: Can the rules for strict mode be extended?

   * 22.3.6: Does strict mode impact performance?

   * 22.3.7: What is the default server SQL mode when My SQL 6.0 is
     installed?

*Questions and Answers* *22.3.1: ** What are server SQL modes?  *

Server SQL modes define what SQL syntax MySQL should support and what
kind of data validation checks it should perform.  This makes it easier
to use MySQL in different environments and to use MySQL together with
other database servers. The MySQL Server apply these modes individually
to different clients. For more information, see *Note server-sql-mode::.

*22.3.2: ** How many server SQL modes are there?  *

Each mode can be independently switched on and off. See *Note
server-sql-mode::, for a complete list of available modes.

*22.3.3: ** How do you determine the server SQL mode?  *

You can set the default SQL mode (for *Note `mysqld': mysqld. startup)
with the `--sql-mode' option. Using the statement *Note `SET
[GLOBAL|SESSION] sql_mode='MODES'': set-option, you can change the
settings from within a connection, either locally to the connection, or
to take effect globally. You can retrieve the current mode by issuing a
`SELECT @@sql_mode' statement.

*22.3.4: ** Is the mode dependent on the database or connection?  *

A mode is not linked to a particular database. Modes can be set locally
to the session (connection), or globally for the server. you can change
these settings using *Note `SET [GLOBAL|SESSION] sql_mode='MODES'':
set-option.

*22.3.5: ** Can the rules for strict mode be extended?  *

When we refer to _strict mode_, we mean a mode where at least one of
the modes `TRADITIONAL', `STRICT_TRANS_TABLES', or `STRICT_ALL_TABLES'
is enabled. Options can be combined, so you can add additional
restrictions to a mode. See *Note server-sql-mode::, for more
information.

*22.3.6: ** Does strict mode impact performance?  *

The intensive validation of input data that some settings requires more
time than if the validation is not done. While the performance impact
is not that great, if you do not require such validation (perhaps your
application already handles all of this), then MySQL gives you the
option of leaving strict mode disabled. However -- if you do require it
-- strict mode can provide such validation.

*22.3.7: ** What is the default server SQL mode when My SQL 6.0 is
installed?  *

By default, no special modes are enabled. See *Note server-sql-mode::,
for information about all available modes and MySQL's default behavior.


File: manual.info,  Node: faqs-stored-procs,  Next: faqs-triggers,  Prev: faqs-sql-modes,  Up: faqs

A.4 MySQL 6.0 FAQ -- Stored Procedures and Functions
====================================================

*Questions*
   * 22.4.1: Does MySQL 6.0 support stored procedures and functions?

   * 22.4.2: Where can I find documentation for MySQL stored procedures
     and stored functions?

   * 22.4.3: Is there a discussion forum for MySQL stored procedures?

   * 22.4.4: Where can I find the ANSI SQL 2003 specification for stored
     procedures?

   * 22.4.5: How do you manage stored routines?

   * 22.4.6: Is there a way to view all stored procedures and stored
     functions in a given database?

   * 22.4.7: Where are stored procedures stored?

   * 22.4.8: Is it possible to group stored procedures or stored
     functions into packages?

   * 22.4.9: Can a stored procedure call another stored procedure?

   * 22.4.10: Can a stored procedure call a trigger?

   * 22.4.11: Can a stored procedure access tables?

   * 22.4.12: Do stored procedures have a statement for raising
     application errors?

   * 22.4.13: Do stored procedures provide exception handling?

   * 22.4.14: Can MySQL 6.0 stored routines return result sets?

   * 22.4.15: Is `WITH RECOMPILE' supported for stored procedures?

   * 22.4.16: Is there a MySQL equivalent to using `mod_plsql' as a
     gateway on Apache to talk directly to a stored procedure in the
     database?

   * 22.4.17: Can I pass an array as input to a stored procedure?

   * 22.4.18: Can I pass a cursor as an `IN' parameter to a stored
     procedure?

   * 22.4.19: Can I return a cursor as an `OUT' parameter from a stored
     procedure?

   * 22.4.20: Can I print out a variable's value within a stored routine
     for debugging purposes?

   * 22.4.21: Can I commit or roll back transactions inside a stored
     procedure?

   * 22.4.22: Do MySQL 6.0 stored procedures and functions work with
     replication?

   * 22.4.23: Are stored procedures and functions created on a master
     server replicated to a slave?

   * 22.4.24: How are actions that take place inside stored procedures
     and functions replicated?

   * 22.4.25: Are there special security requirements for using stored
     procedures and functions together with replication?

   * 22.4.26: What limitations exist for replicating stored procedure
     and function actions?

   * 22.4.27: Do the preceding limitations affect MySQL's ability to do
     point-in-time recovery?

   * 22.4.28: What is being done to correct the aforementioned
     limitations?

*Questions and Answers* *22.4.1: ** Does MySQL 6.0 support stored
procedures and functions?  *

Yes. MySQL 6.0 supports two types of stored routines -- stored
procedures and stored functions.

*22.4.2: ** Where can I find documentation for MySQL stored procedures
and stored functions?  *

See *Note stored-routines::.

*22.4.3: ** Is there a discussion forum for MySQL stored procedures?  *

Yes. See http://forums.mysql.com/list.php?98
(http://forums.mysql.com/list.php?98).

*22.4.4: ** Where can I find the ANSI SQL 2003 specification for stored
procedures?  *

Unfortunately, the official specifications are not freely available
(ANSI makes them available for purchase). However, there are books --
such as `SQL-99 Complete, Really' by Peter Gulutzan and Trudy Pelzer --
which give a comprehensive overview of the standard, including coverage
of stored procedures.

*22.4.5: ** How do you manage stored routines?  *

It is always good practice to use a clear naming scheme for your stored
routines. You can manage stored procedures with `CREATE
[FUNCTION|PROCEDURE]', `ALTER [FUNCTION|PROCEDURE]', `DROP
[FUNCTION|PROCEDURE]', and `SHOW CREATE [FUNCTION|PROCEDURE]'. You can
obtain information about existing stored procedures using the *Note
`ROUTINES': routines-table. table in the `INFORMATION_SCHEMA' database
(see *Note routines-table::).

*22.4.6: ** Is there a way to view all stored procedures and stored
functions in a given database?  *

Yes. For a database named DBNAME, use this query on the *Note
`INFORMATION_SCHEMA.ROUTINES': routines-table.  table:

     SELECT ROUTINE_TYPE, ROUTINE_NAME
         FROM INFORMATION_SCHEMA.ROUTINES
         WHERE ROUTINE_SCHEMA='DBNAME';

For more information, see *Note routines-table::.

The body of a stored routine can be viewed using *Note `SHOW CREATE
FUNCTION': show-create-function. (for a stored function) or *Note `SHOW
CREATE PROCEDURE': show-create-procedure. (for a stored procedure). See
*Note show-create-procedure::, for more information.

*22.4.7: ** Where are stored procedures stored?  *

In the `proc' table of the `mysql' system database. However, you should
not access the tables in the system database directly. Instead, use
*Note `SHOW CREATE FUNCTION': show-create-function. to obtain
information about stored functions, and *Note `SHOW CREATE PROCEDURE':
show-create-procedure. to obtain information about stored procedures.
See *Note show-create-procedure::, for more information about these
statements.

You can also query the *Note `ROUTINES': routines-table.  table in the
`INFORMATION_SCHEMA' database -- see *Note routines-table::, for
information about this table.

*22.4.8: ** Is it possible to group stored procedures or stored
functions into packages?  *

No. This is not supported in MySQL 6.0.

*22.4.9: ** Can a stored procedure call another stored procedure?  *

Yes.

*22.4.10: ** Can a stored procedure call a trigger?  *

A stored procedure can execute an SQL statement, such as an *Note
`UPDATE': update, that causes a trigger to activate.

*22.4.11: ** Can a stored procedure access tables?  *

Yes. A stored procedure can access one or more tables as required.

*22.4.12: ** Do stored procedures have a statement for raising
application errors?  *

Yes. As of MySQL 6.0.11, MySQL implements the SQL standard *Note
`SIGNAL': signal. and *Note `RESIGNAL': resignal. statements. See *Note
signal-resignal::.

*22.4.13: ** Do stored procedures provide exception handling?  *

MySQL implements *Note `HANDLER': handler.  definitions according to
the SQL standard. See *Note declare-handler::, for details.

*22.4.14: ** Can MySQL 6.0 stored routines return result sets?  *

_Stored procedures_ can, but stored functions cannot. If you perform an
ordinary *Note `SELECT': select. inside a stored procedure, the result
set is returned directly to the client. You need to use the MySQL 4.1
(or above) client-server protocol for this to work. This means that --
for instance -- in PHP, you need to use the `mysqli' extension rather
than the old `mysql' extension.

*22.4.15: ** Is `WITH RECOMPILE' supported for stored procedures?  *

Not in MySQL 6.0.

*22.4.16: ** Is there a MySQL equivalent to using `mod_plsql' as a
gateway on Apache to talk directly to a stored procedure in the
database?  *

There is no equivalent in MySQL 6.0.

*22.4.17: ** Can I pass an array as input to a stored procedure?  *

Not in MySQL 6.0.

*22.4.18: ** Can I pass a cursor as an `IN' parameter to a stored
procedure?  *

In MySQL 6.0, cursors are available inside stored procedures only.

*22.4.19: ** Can I return a cursor as an `OUT' parameter from a stored
procedure?  *

In MySQL 6.0, cursors are available inside stored procedures only.
However, if you do not open a cursor on a *Note `SELECT': select, the
result will be sent directly to the client. You can also `SELECT INTO'
variables. See *Note select::.

*22.4.20: ** Can I print out a variable's value within a stored routine
for debugging purposes?  *

Yes, you can do this in a _stored procedure_, but not in a stored
function. If you perform an ordinary *Note `SELECT': select.  inside a
stored procedure, the result set is returned directly to the client.
You will need to use the MySQL 4.1 (or above) client-server protocol
for this to work. This means that -- for instance -- in PHP, you need to
use the `mysqli' extension rather than the old `mysql' extension.

*22.4.21: ** Can I commit or roll back transactions inside a stored
procedure?  *

Yes. However, you cannot perform transactional operations within a
stored function.

*22.4.22: ** Do MySQL 6.0 stored procedures and functions work with
replication?  *

Yes, standard actions carried out in stored procedures and functions
are replicated from a master MySQL server to a slave server. There are
a few limitations that are described in detail in *Note
stored-programs-logging::.

*22.4.23: ** Are stored procedures and functions created on a master
server replicated to a slave?  *

Yes, creation of stored procedures and functions carried out through
normal DDL statements on a master server are replicated to a slave, so
the objects will exist on both servers. `ALTER' and `DROP' statements
for stored procedures and functions are also replicated.

*22.4.24: ** How are actions that take place inside stored procedures
and functions replicated?  *

MySQL records each DML event that occurs in a stored procedure and
replicates those individual actions to a slave server. The actual calls
made to execute stored procedures are not replicated.

Stored functions that change data are logged as function invocations,
not as the DML events that occur inside each function.

*22.4.25: ** Are there special security requirements for using stored
procedures and functions together with replication?  *

Yes. Because a slave server has authority to execute any statement read
from a master's binary log, special security constraints exist for
using stored functions with replication. If replication or binary
logging in general (for the purpose of point-in-time recovery) is
active, then MySQL DBAs have two security options open to them:

  1. Any user wishing to create stored functions must be granted the
     `SUPER' privilege.

  2. Alternatively, a DBA can set the `log_bin_trust_function_creators'
     system variable to 1, which enables anyone with the standard
     `CREATE ROUTINE' privilege to create stored functions.

*22.4.26: ** What limitations exist for replicating stored procedure and
function actions?  *

Non-deterministic (random) or time-based actions embedded in stored
procedures may not replicate properly. By their very nature, randomly
produced results are not predictable and cannot be exactly reproduced,
and therefore, random actions replicated to a slave will not mirror
those performed on a master. Note that declaring stored functions to be
`DETERMINISTIC' or setting the `log_bin_trust_function_creators' system
variable to 0 will not allow random-valued operations to be invoked.

In addition, time-based actions cannot be reproduced on a slave because
the timing of such actions in a stored procedure is not reproducible
through the binary log used for replication. It records only DML events
and does not factor in timing constraints.

Finally, non-transactional tables for which errors occur during large
DML actions (such as bulk inserts) may experience replication issues in
that a master may be partially updated from DML activity, but no
updates are done to the slave because of the errors that occurred. A
workaround is for a function's DML actions to be carried out with the
`IGNORE' keyword so that updates on the master that cause errors are
ignored and updates that do not cause errors are replicated to the
slave.

*22.4.27: ** Do the preceding limitations affect MySQL's ability to do
point-in-time recovery?  *

The same limitations that affect replication do affect point-in-time
recovery.

*22.4.28: ** What is being done to correct the aforementioned
limitations?  *

You can choose either statement-based replication or row-based
replication. The original replication implementation is based on
statement-based binary logging.  Row-based binary logging resolves the
limitations mentioned earlier.

The default format, _mixed_ replication, is also available (by starting
the server with `--binlog-format=mixed'). This hybrid, `smart' form of
replication `knows' whether statement-level replication can safely be
used, or row-level replication is required.

For additional information, see *Note replication-formats::.


File: manual.info,  Node: faqs-triggers,  Next: faqs-views,  Prev: faqs-stored-procs,  Up: faqs

A.5 MySQL 6.0 FAQ -- Triggers
=============================

*Questions*
   * 22.5.1: Where can I find the documentation for MySQL 6.0 triggers?

   * 22.5.2: Is there a discussion forum for MySQL Triggers?

   * 22.5.3: Does MySQL 6.0 have statement-level or row-level triggers?

   * 22.5.4: Are there any default triggers?

   * 22.5.5: How are triggers managed in MySQL?

   * 22.5.6: Is there a way to view all triggers in a given database?

   * 22.5.7: Where are triggers stored?

   * 22.5.8: Can a trigger call a stored procedure?

   * 22.5.9: Can triggers access tables?

   * 22.5.10: Can triggers call an external application through a UDF?

   * 22.5.11: Is it possible for a trigger to update tables on a remote
     server?

   * 22.5.12: Do triggers work with replication?

   * 22.5.13: How are actions carried out through triggers on a master
     replicated to a slave?

*Questions and Answers* *22.5.1: ** Where can I find the documentation
for MySQL 6.0 triggers?  *

See *Note triggers::.

*22.5.2: ** Is there a discussion forum for MySQL Triggers?  *

Yes. It is available at `http://forums.mysql.com/list.php?99'.

*22.5.3: ** Does MySQL 6.0 have statement-level or row-level triggers?
*

In MySQL 6.0, all triggers are `FOR EACH ROW' -- that is, the trigger
is activated for each row that is inserted, updated, or deleted. MySQL
6.0 does not support triggers using `FOR EACH STATEMENT'.

*22.5.4: ** Are there any default triggers?  *

Not explicitly. MySQL does have specific special behavior for some
*Note `TIMESTAMP': datetime. columns, as well as for columns which are
defined using `AUTO_INCREMENT'.

*22.5.5: ** How are triggers managed in MySQL?  *

In MySQL 6.0, triggers can be created using the *Note `CREATE TRIGGER':
create-trigger. statement, and dropped using *Note `DROP TRIGGER':
drop-trigger.  See *Note create-trigger::, and *Note drop-trigger::,
for more about these statements.

Information about triggers can be obtained by querying the *Note
`INFORMATION_SCHEMA.TRIGGERS': triggers-table.  table. See *Note
triggers-table::.

*22.5.6: ** Is there a way to view all triggers in a given database?  *

Yes. You can obtain a listing of all triggers defined on database
`dbname' using a query on the *Note `INFORMATION_SCHEMA.TRIGGERS':
triggers-table.  table such as the one shown here:

     SELECT TRIGGER_NAME, EVENT_MANIPULATION, EVENT_OBJECT_TABLE, ACTION_STATEMENT
         FROM INFORMATION_SCHEMA.TRIGGERS
         WHERE TRIGGER_SCHEMA='DBNAME';

For more information about this table, see *Note triggers-table::.

You can also use the *Note `SHOW TRIGGERS': show-triggers. statement,
which is specific to MySQL.  See *Note show-triggers::.

*22.5.7: ** Where are triggers stored?  *

Triggers for a table are currently stored in `.TRG' files, with one
such file one per table.

*22.5.8: ** Can a trigger call a stored procedure?  *

Yes.

*22.5.9: ** Can triggers access tables?  *

A trigger can access both old and new data in its own table.  A trigger
can also affect other tables, but it is not permitted to modify a table
that is already being used (for reading or writing) by the statement
that invoked the function or trigger.

*22.5.10: ** Can triggers call an external application through a UDF?  *

Yes. For example, a trigger could invoke the `sys_exec()' UDF available
at MySQL Forge here:
`http://forge.mysql.com/projects/project.php?id=211'

*22.5.11: ** Is it possible for a trigger to update tables on a remote
server?  *

Yes. A table on a remote server could be updated using the `FEDERATED'
storage engine. (See *Note federated-storage-engine::).

*22.5.12: ** Do triggers work with replication?  *

Yes. However, the way in which they work depends whether you are using
MySQL's `classic' statement-based replication available in all versions
of MySQL, or the row-based replication format introduced in MySQL 5.1.

When using statement-based replication, triggers on the slave are
executed by statements that are executed on the master (and replicated
to the slave).

When using row-based replication, triggers are not executed on the
slave due to statements that were run on the master and then replicated
to the slave. Instead, when using row-based replication, the changes
caused by executing the trigger on the master are applied on the slave.

For more information, see *Note replication-features-triggers::.

*22.5.13: ** How are actions carried out through triggers on a master
replicated to a slave?  *

Again, this depends on whether you are using statement-based or
row-based replication.

Statement-based replication

First, the triggers that exist on a master must be re-created on the
slave server. Once this is done, the replication flow works as any
other standard DML statement that participates in replication. For
example, consider a table `EMP' that has an `AFTER' insert trigger,
which exists on a master MySQL server. The same `EMP' table and `AFTER'
insert trigger exist on the slave server as well. The replication flow
would be:

  1. An *Note `INSERT': insert. statement is made to `EMP'.

  2. The `AFTER' trigger on `EMP' activates.

  3. The *Note `INSERT': insert. statement is written to the binary log.

  4. The replication slave picks up the *Note `INSERT': insert.
     statement to `EMP' and executes it.

  5. The `AFTER' trigger on `EMP' that exists on the slave activates.

Row-based replication

When you use row-based replication, the changes caused by executing the
trigger on the master are applied on the slave. However, the triggers
themselves are not actually executed on the slave under row-based
replication. This is because, if both the master and the slave applied
the changes from the master and -- in addition -- the trigger causing
these changes were applied on the slave, the changes would in effect be
applied twice on the slave, leading to different data on the master and
the slave.

In most cases, the outcome is the same for both row-based and
statement-based replication. However, if you use different triggers on
the master and slave, you cannot use row-based replication. (This is
because the row-based format replicates the changes made by triggers
executing on the master to the slaves, rather than the statements that
caused the triggers to execute, and the corresponding triggers on the
slave are not executed.) Instead, any statements causing such triggers
to be executed must be replicated using statement-based replication.

For more information, see *Note replication-features-triggers::.


File: manual.info,  Node: faqs-views,  Next: faqs-information-schema,  Prev: faqs-triggers,  Up: faqs

A.6 MySQL 6.0 FAQ -- Views
==========================

*Questions*
   * 22.6.1: Where can I find documentation covering MySQL Views?

   * 22.6.2: Is there a discussion forum for MySQL Views?

   * 22.6.3: What happens to a view if an underlying table is dropped or
     renamed?

   * 22.6.4: Does MySQL 6.0 have table snapshots?

   * 22.6.5: Does MySQL 6.0 have materialized views?

   * 22.6.6: Can you insert into views that are based on joins?

*Questions and Answers* *22.6.1: ** Where can I find documentation
covering MySQL Views?  *

See *Note views::.

*22.6.2: ** Is there a discussion forum for MySQL Views?  *

Yes. See http://forums.mysql.com/list.php?100
(http://forums.mysql.com/list.php?100)

*22.6.3: ** What happens to a view if an underlying table is dropped or
renamed?  *

After a view has been created, it is possible to drop or alter a table
or view to which the definition refers. To check a view definition for
problems of this kind, use the *Note `CHECK TABLE': check-table.
statement. (See *Note check-table::.)

*22.6.4: ** Does MySQL 6.0 have table snapshots?  *

No.

*22.6.5: ** Does MySQL 6.0 have materialized views?  *

No.

*22.6.6: ** Can you insert into views that are based on joins?  *

It is possible, provided that your *Note `INSERT': insert. statement
has a column list that makes it clear there is only one table involved.

You _cannot_ insert into multiple tables with a single insert on a view.


File: manual.info,  Node: faqs-information-schema,  Next: faqs-migration,  Prev: faqs-views,  Up: faqs

A.7 MySQL 5.0 FAQ -- `INFORMATION_SCHEMA'
=========================================

*Questions*
   * 22.7.1: Where can I find documentation for the MySQL
     `INFORMATION_SCHEMA' database?

   * 22.7.2: Is there a discussion forum for `INFORMATION_SCHEMA'?

   * 22.7.3: Where can I find the ANSI SQL 2003 specification for
     `INFORMATION_SCHEMA'?

   * 22.7.4: What is the difference between the Oracle Data Dictionary
     and MySQL's `INFORMATION_SCHEMA'?

   * 22.7.5: Can I add to or otherwise modify the tables found in the
     `INFORMATION_SCHEMA' database?

*Questions and Answers* *22.7.1: ** Where can I find documentation for
the MySQL `INFORMATION_SCHEMA' database?  *

See *Note information-schema::

*22.7.2: ** Is there a discussion forum for `INFORMATION_SCHEMA'?  *

See http://forums.mysql.com/list.php?101
(http://forums.mysql.com/list.php?101).

*22.7.3: ** Where can I find the ANSI SQL 2003 specification for
`INFORMATION_SCHEMA'?  *

Unfortunately, the official specifications are not freely available.
(ANSI makes them available for purchase.)  However, there are books
available -- such as `SQL-99 Complete, Really' by Peter Gulutzan and
Trudy Pelzer -- which give a comprehensive overview of the standard,
including `INFORMATION_SCHEMA'.

*22.7.4: ** What is the difference between the Oracle Data Dictionary
and MySQL's `INFORMATION_SCHEMA'?  *

Both Oracle and MySQL provide metadata in tables. However, Oracle and
MySQL use different table names and column names.  MySQL's
implementation is more similar to those found in DB2 and SQL Server,
which also support `INFORMATION_SCHEMA' as defined in the SQL standard.

*22.7.5: ** Can I add to or otherwise modify the tables found in the
`INFORMATION_SCHEMA' database?  *

No. Since applications may rely on a certain standard structure, this
should not be modified. For this reason, _we cannot support bugs or
other issues which result from modifying `INFORMATION_SCHEMA' tables or
data_.


File: manual.info,  Node: faqs-migration,  Next: faqs-security,  Prev: faqs-information-schema,  Up: faqs

A.8 MySQL 6.0 FAQ -- Migration
==============================

*Questions*
   * 22.8.1: Where can I find information on how to migrate from MySQL
     5.1 to MySQL 6.0?

   * 22.8.2: How has storage engine (table type) support changed in
     MySQL 6.0 from previous versions?

*Questions and Answers* *22.8.1: ** Where can I find information on how
to migrate from MySQL 5.1 to MySQL 6.0?  *

For detailed upgrade information, see *Note upgrade::. We recommend
that you do not skip a major version when upgrading, but rather
complete the process in steps, upgrading from one major version to the
next in each step. This may seem more complicated, but it will you save
time and trouble -- if you encounter problems during the upgrade, their
origin will be easier to identify, either by you or -- if you have a
MySQL Enterprise subscription -- by MySQL support.

*22.8.2: ** How has storage engine (table type) support changed in MySQL
6.0 from previous versions?  *

Storage engine support has changed as follows:

   * Support for `ISAM' tables was removed in MySQL 5.0 and you should
     now use the `MyISAM' storage engine in place of `ISAM'. To convert
     a table TBLNAME from `ISAM' to `MyISAM', simply issue a statement
     such as this one:

          ALTER TABLE TBLNAME ENGINE=MYISAM;

   * Internal `RAID' for `MyISAM' tables was also removed in MySQL 5.0.
     This was formerly used to allow large tables in file systems that
     did not support file sizes greater than 2GB. All modern file
     systems allow for larger tables; in addition, there are now other
     solutions such as `MERGE' tables and views.

   * The *Note `VARCHAR': char. column type now retains trailing spaces
     in all storage engines.

   * `MEMORY' tables (formerly known as `HEAP' tables) can also contain
     *Note `VARCHAR': char. columns.


File: manual.info,  Node: faqs-security,  Next: faqs-mysql-cluster,  Prev: faqs-migration,  Up: faqs

A.9 MySQL 6.0 FAQ -- Security
=============================

*Questions*
   * 22.9.1: Where can I find documentation that addresses security
     issues for MySQL?

   * 22.9.2: Does MySQL 6.0 have native support for SSL?

   * 22.9.3: Is SSL support be built into MySQL binaries, or must I
     recompile the binary myself to enable it?

   * 22.9.4: Does MySQL 6.0 have built-in authentication against LDAP
     directories?

   * 22.9.5: Does MySQL 6.0 include support for Roles Based Access
     Control (RBAC)?

*Questions and Answers* *22.9.1: ** Where can I find documentation that
addresses security issues for MySQL?  *

The best place to start is *Note security::.

Other portions of the MySQL Documentation which you may find useful
with regard to specific security concerns include the following:

   * *Note security-guidelines::.

   * *Note security-against-attack::.

   * *Note resetting-permissions::.

   * *Note changing-mysql-user::.

   * *Note udf-security::.

   * *Note privileges-options::.

   * *Note load-data-local::.

   * *Note post-installation::.

   * *Note selinux::.

   * *Note secure-basics::.

MySQL Enterprise

The MySQL Enterprise Monitor enforces best practices for maximizing the
security of your servers. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*22.9.2: ** Does MySQL 6.0 have native support for SSL?  *

Most 6.0 binaries have support for SSL connections between the client
and server. We can't currently build with the new YaSSL library
everywhere, as it is still quite new and does not compile on all
platforms yet. See *Note secure-connections::.

You can also tunnel a connection via SSH, if (for instance) if the
client application doesn't support SSL connections.  For an example,
see *Note windows-and-ssh::.

*22.9.3: ** Is SSL support be built into MySQL binaries, or must I
recompile the binary myself to enable it?  *

Most 6.0 binaries have SSL enabled for client-server connections that
are secured, authenticated, or both. However, the YaSSL library
currently does not compile on all platforms. See *Note
secure-connections::, for a complete listing of supported and
unsupported platforms.

*22.9.4: ** Does MySQL 6.0 have built-in authentication against LDAP
directories?  *

No. Support for external authentication methods is on the MySQL roadmap
as a `rolling feature', which means that we plan to implement it in the
future, but we have not yet determined when this will be done.

*22.9.5: ** Does MySQL 6.0 include support for Roles Based Access
Control (RBAC)?  *

No. Support for roles is on the MySQL roadmap as a `rolling feature',
which means that we plan to implement it in the future, but we have not
yet determined when this will be done.


File: manual.info,  Node: faqs-mysql-cluster,  Next: faqs-cjk,  Prev: faqs-security,  Up: faqs

A.10 MySQL 6.0 FAQ -- MySQL Cluster
===================================

Beginning with MySQL 6.0.5, MySQL Cluster is no longer supported in
MySQL Server 6.0 releases. Instead, MySQL Cluster is now released as a
separate product, available in 2 release series -- MySQL Cluster NDB
6.2 and MySQL Cluster NDB 6.3. You should use one of these for new
deployments, and plan to upgrade to one of them if you are using a
previous version of MySQL with clustering support. For an overview of
improvements in MySQL Cluster NDB 6.2 and 6.3, see Features Added in
MySQL Cluster NDB 6.2
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-changes-5-1-ndb-6-2.html),
and Features Added in MySQL Cluster NDB 6.3
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-changes-5-1-ndb-6-3.html).

For answers to frequently asked questions about MySQL Cluster, see
MySQL 5.1 FAQ -- MySQL Cluster
(http://dev.mysql.com/doc/refman/5.1/en/faqs-mysql-cluster.html). For
detailed information about deploying and using MySQL Cluster, see MySQL
Cluster NDB 6.X/7.X
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html).


File: manual.info,  Node: faqs-cjk,  Next: faqs-connectors-apis,  Prev: faqs-mysql-cluster,  Up: faqs

A.11 MySQL 6.0 FAQ -- MySQL Chinese, Japanese, and Korean Character Sets
========================================================================

This set of Frequently Asked Questions derives from the experience of
MySQL's Support and Development groups in handling many inquiries about
CJK (Chinese-Japanese-Korean) issues.

*Questions*
   * 22.11.1: 

     What CJK character sets are available in MySQL?

   * 22.11.2: I have inserted CJK characters into my table. Why does
     *Note `SELECT': select. display them as `?' characters?

   * 22.11.3: 

     What problems should I be aware of when working with the Big5
     Chinese character set?

   * 22.11.4: 

     Why do Japanese character set conversions fail?

   * 22.11.5: What should I do if I want to convert SJIS `81CA' to
     `cp932'?

   * 22.11.6: 

     How does MySQL represent the Yen (`¥') sign?

   * 22.11.7: Do MySQL plan to make a separate character set where `5C'
     is the Yen sign, as at least one other major DBMS does?

   * 22.11.8: 

     Of what issues should I be aware when working with Korean
     character sets in MySQL?

   * 22.11.9: 

     Why do I get `Data truncated' error messages?

   * 22.11.10: 

     Why does my GUI front end or browser not display CJK characters
     correctly in my application using Access, PHP, or another API?

   * 22.11.11: 

     I've upgraded to MySQL 6.0. How can I revert to behavior like that
     in MySQL 4.0 with regard to character sets?

   * 22.11.12: 

     Why do some `LIKE' and `FULLTEXT' searches with CJK characters
     fail?

   * 22.11.13: 

     How do I know whether character X is available in all character
     sets?

   * 22.11.14: 

     Why don't CJK strings sort correctly in Unicode? (I)

   * 22.11.15: 

     Why don't CJK strings sort correctly in Unicode? (II)

   * 22.11.16: 

     Why are my supplementary characters rejected by MySQL?

   * 22.11.17: 

     Shouldn't it be `CJKV'?

   * 22.11.18: 

     Does MySQL allow CJK characters to be used in database and table
     names?

   * 22.11.19: 

     Where can I find translations of the MySQL Manual into Chinese,
     Japanese, and Korean?

   * 22.11.20: Where can I get help with CJK and related issues in
     MySQL?

*Questions and Answers* *22.11.1: ** ** ** ** ** ** What CJK character
sets are available in MySQL?  *

The list of CJK character sets may vary depending on your MySQL
version. For example, the `eucjpms' character set was not supported
prior to MySQL 5.0.3.  However, since the name of the applicable
language appears in the `DESCRIPTION' column for every entry in the
*Note `INFORMATION_SCHEMA.CHARACTER_SETS': character-sets-table.
table, you can obtain a current list of all the non-Unicode CJK
character sets using this query:

     mysql> SELECT CHARACTER_SET_NAME, DESCRIPTION
         -> FROM INFORMATION_SCHEMA.CHARACTER_SETS
         -> WHERE DESCRIPTION LIKE '%Chinese%'
         -> OR DESCRIPTION LIKE '%Japanese%'
         -> OR DESCRIPTION LIKE '%Korean%'
         -> ORDER BY CHARACTER_SET_NAME;
     +--------------------+---------------------------+
     | CHARACTER_SET_NAME | DESCRIPTION               |
     +--------------------+---------------------------+
     | big5               | Big5 Traditional Chinese  |
     | cp932              | SJIS for Windows Japanese |
     | eucjpms            | UJIS for Windows Japanese |
     | euckr              | EUC-KR Korean             |
     | gb2312             | GB2312 Simplified Chinese |
     | gbk                | GBK Simplified Chinese    |
     | sjis               | Shift-JIS Japanese        |
     | ujis               | EUC-JP Japanese           |
     +--------------------+---------------------------+
     8 rows in set (0.01 sec)

(See *Note character-sets-table::, for more information.)

MySQL supports the two common variants of the _GB_ (_Guojia Biaozhun_,
or _National Standard_, or _Simplified Chinese_) character sets which
are official in the People's Republic of China: `gb2312' and `gbk'.
Sometimes people try to insert `gbk' characters into `gb2312', and it
works most of the time because `gbk' is a superset of `gb2312' -- but
eventually they try to insert a rarer Chinese character and it doesn't
work. (See Bug#16072 (http://bugs.mysql.com/16072) for an example).

Here, we try to clarify exactly what characters are legitimate in
`gb2312' or `gbk', with reference to the official documents. Please
check these references before reporting `gb2312' or `gbk' bugs.

   * For a complete listing of the `gb2312' characters, ordered
     according to the `gb2312_chinese_ci' collation: gb2312
     (http://www.collation-charts.org/mysql60/by-charset.html#gb2312)

   * MySQL's `gbk' is in reality `Microsoft code page 936'. This differs
     from the official `gbk' for characters `A1A4' (middle dot), `A1AA'
     (em dash), `A6E0-A6F5', and `A8BB-A8C0'. For a listing of the
     differences, see
     `http://recode.progiciels-bpi.ca/showfile.html?name=dist/libiconv/gbk.h'.

   * For a listing of `gbk'/Unicode mappings, see
     `http://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WINDOWS/CP936.TXT'.

   * For MySQL's listing of `gbk' characters, see gbk
     (http://www.collation-charts.org/mysql60/by-charset.html#gbk).

*22.11.2: ** I have inserted CJK characters into my table. Why does
*Note `SELECT': select. display them as `?' characters?  *

This problem is usually due to a setting in MySQL that doesn't match
the settings for the application program or the operating system. Here
are some common steps for correcting these types of issues:

   * _Be certain of what MySQL version you are using_.

     Use the statement `SELECT VERSION();' to determine this.

   * _Make sure that the database is actually using the desired
     character set_.

     People often think that the client character set is always the
     same as either the server character set or the character set used
     for display purposes. However, both of these are false
     assumptions. You can make sure by checking the result of `SHOW
     CREATE TABLE TABLENAME' or -- better -- yet by using this
     statement:

          SELECT character_set_name, collation_name
              FROM information_schema.columns
              WHERE table_schema = your_database_name
                  AND table_name = your_table_name
                  AND column_name = your_column_name;

   * _Determine the hexadecimal value of the character or characters
     that are not being displayed correctly_.

     You can obtain this information for a column COLUMN_NAME in the
     table TABLE_NAME using the following query:

          SELECT HEX(COLUMN_NAME)
          FROM TABLE_NAME;

     `3F' is the encoding for the `?' character; this means that `?' is
     the character actually stored in the column. This most often
     happens because of a problem converting a particular character
     from your client character set to the target character set.

   * _Make sure that a round trip possible -- that is, when you select
     LITERAL (or _INTRODUCER HEXADECIMAL-VALUE), you obtain LITERAL as a
     result_.

     For example, the Japanese _Katakana_ character _Pe_ (`ペ'')
     exists in all CJK character sets, and has the code point value
     (hexadecimal coding) `0x30da'. To test a round trip for this
     character, use this query:

          SELECT 'ペ' AS `ペ`;         /* or SELECT _ucs2 0x30da; */

     If the result is not also `ペ', then the round trip has failed.

     For bug reports regarding such failures, we might ask you to
     follow up with `SELECT HEX('ペ');'. Then we can determine whether
     the client encoding is correct.

   * _Make sure that the problem is not with the browser or other
     application, rather than with MySQL_.

     Use the *Note `mysql': mysql. client program (on Windows: *Note
     `mysql.exe': mysql.) to accomplish this task. If *Note `mysql':
     mysql. displays correctly but your application doesn't, then your
     problem is probably due to system settings.

     To find out what your settings are, use the *Note `SHOW
     VARIABLES': show-variables. statement, whose output should
     resemble what is shown here:

          mysql> SHOW VARIABLES LIKE 'char%';
          +--------------------------+----------------------------------------+
          | Variable_name            | Value                                  |
          +--------------------------+----------------------------------------+
          | character_set_client     | utf8                                   |
          | character_set_connection | utf8                                   |
          | character_set_database   | latin1                                 |
          | character_set_filesystem | binary                                 |
          | character_set_results    | utf8                                   |
          | character_set_server     | latin1                                 |
          | character_set_system     | utf8                                   |
          | character_sets_dir       | /usr/local/mysql/share/mysql/charsets/ |
          +--------------------------+----------------------------------------+
          8 rows in set (0.03 sec)

     These are typical character-set settings for an
     international-oriented client (notice the use of `utf8' Unicode)
     connected to a server in the West (`latin1' is a West Europe
     character set and a default for MySQL).

     Although Unicode (usually the `utf8' variant on Unix, and the
     `ucs2' variant on Windows) is preferable to Latin, it is often not
     what your operating system utilities support best. Many Windows
     users find that a Microsoft character set, such as `cp932' for
     Japanese Windows, is suitable.

     If you cannot control the server settings, and you have no idea
     what your underlying computer is, then try changing to a common
     character set for the country that you're in (`euckr' = Korea;
     `gb2312' or `gbk' = People's Republic of China; `big5' = Taiwan;
     `sjis', `ujis', `cp932', or `eucjpms' = Japan; `ucs2' or `utf8' =
     anywhere). Usually it is necessary to change only the client and
     connection and results settings. There is a simple statement which
     changes all three at once: `SET NAMES'. For example:

          SET NAMES 'big5';

     Once the setting is correct, you can make it permanent by editing
     `my.cnf' or `my.ini'. For example you might add lines looking like
     these:

          [mysqld]
          character-set-server=big5
          [client]
          default-character-set=big5

     It is also possible that there are issues with the API
     configuration setting being used in your application; see `Why
     does my GUI front end or browser not display CJK characters
     correctly...?' for more information.

*22.11.3: ** ** ** ** What problems should I be aware of when working
with the Big5 Chinese character set?  *

MySQL supports the Big5 character set which is common in Hong Kong and
Taiwan (Republic of China). MySQL's `big5' is in reality Microsoft code
page 950, which is very similar to the original `big5' character set.
We changed to this

character set starting with MySQL version 4.1.16 / 5.0.16 (as a result
of Bug#12476 (http://bugs.mysql.com/12476)). For example, the following
statements work in current versions of MySQL, but not in old versions:

     mysql> CREATE TABLE big5 (BIG5 CHAR(1) CHARACTER SET BIG5);
     Query OK, 0 rows affected (0.13 sec)

     mysql> INSERT INTO big5 VALUES (0xf9dc);
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT * FROM big5;
     +------+
     | big5 |
     +------+
     | 嫺  |
     +------+
     1 row in set (0.02 sec)

A feature request for adding `HKSCS' extensions has been filed. People
who need this extension may find the suggested patch for Bug#13577
(http://bugs.mysql.com/13577) to be of interest.

*22.11.4: ** ** ** ** Why do Japanese character set conversions fail?  *

MySQL supports the `sjis', `ujis', `cp932', and eucjpms character sets,
as well as Unicode. A common need is to convert between character sets.
For example, there might be a Unix server (typically with `sjis' or
`ujis') and a Windows client (typically with `cp932').

In the following conversion table, the `ucs2' column represents the
source, and the `sjis', `cp932', `ujis', and `eucjpms' columns
represent the destinations -- that is, the last 4 columns provide the
hexadecimal result when we use `CONVERT(ucs2)' or we assign a `ucs2'
column containing the value to an `sjis', `cp932', `ujis', or `eucjpms'
column.

Character Name                ucs2      sjis      cp932     ujis      eucjpms
BROKEN BAR                    00A6      3F        3F        8FA2C3    3F
FULLWIDTH BROKEN BAR          FFE4      3F        FA55      3F        8FA2
YEN SIGN                      00A5      3F        3F        20        3F
FULLWIDTH YEN SIGN            FFE5      818F      818F      A1EF      3F
TILDE                         007E      7E        7E        7E        7E
OVERLINE                      203E      3F        3F        20        3F
HORIZONTAL BAR                2015      815C      815C      A1BD      A1BD
EM DASH                       2014      3F        3F        3F        3F
REVERSE SOLIDUS               005C      815F      5C        5C        5C
FULLWIDTH ""                  FF3C      3F        815F      3F        A1C0
WAVE DASH                     301C      8160      3F        A1C1      3F
FULLWIDTH TILDE               FF5E      3F        8160      3F        A1C1
DOUBLE VERTICAL LINE          2016      8161      3F        A1C2      3F
PARALLEL TO                   2225      3F        8161      3F        A1C2
MINUS SIGN                    2212      817C      3F        A1DD      3F
FULLWIDTH HYPHEN-MINUS        FF0D      3F        817C      3F        A1DD
CENT SIGN                     00A2      8191      3F        A1F1      3F
FULLWIDTH CENT SIGN           FFE0      3F        8191      3F        A1F1
POUND SIGN                    00A3      8192      3F        A1F2      3F
FULLWIDTH POUND SIGN          FFE1      3F        8192      3F        A1F2
NOT SIGN                      00AC      81CA      3F        A2CC      3F
FULLWIDTH NOT SIGN            FFE2      3F        81CA      3F        A2CC

Now consider the following portion of the table.

                                         ucs2        sjis        cp932
NOT SIGN                                 00AC        81CA        3F
FULLWIDTH NOT SIGN                       FFE2        3F          81CA

This means that MySQL converts the `NOT SIGN' (Unicode `U+00AC') to
`sjis' code point `0x81CA' and to `cp932' code point `3F'. (`3F' is the
question mark (`?') -- this is what is always used when the conversion
cannot be performed.

*22.11.5: ** What should I do if I want to convert SJIS `81CA' to
`cp932'?  *

Our answer is: `?'. There are serious complaints about this: many
people would prefer a `loose' conversion, so that `81CA (NOT SIGN)' in
`sjis' becomes `81CA (FULLWIDTH NOT SIGN)' in `cp932'. We are
considering a change to this behavior.

*22.11.6: ** ** ** ** How does MySQL represent the Yen (`¥') sign?  *

A problem arises because some versions of Japanese character sets (both
`sjis' and `euc') treat `5C' as a _reverse solidus_ (`\' -- also known
as a backslash), and others treat it as a yen sign (`¥').

MySQL follows only one version of the JIS (Japanese Industrial
Standards) standard description. In MySQL, _`5C' is always the reverse
solidus (`\')_.

*22.11.7: ** Do MySQL plan to make a separate character set where `5C'
is the Yen sign, as at least one other major DBMS does?  *

This is one possible solution to the Yen sign issue; however, this will
not happen in MySQL 5.1 or 5.2.

*22.11.8: ** ** ** ** Of what issues should I be aware when working
with Korean character sets in MySQL?  *

In theory, while there have been several versions of the `euckr'
(_Extended Unix Code Korea_) character set, only one problem has been
noted.

We use the `ASCII' variant of EUC-KR, in which the code point `0x5c' is
REVERSE SOLIDUS, that is `\', instead of the `KS-Roman' variant of
EUC-KR, in which the code point `0x5c' is `WON SIGN'(`₩'). This means
that you cannot convert Unicode `U+20A9' to `euckr':

     mysql> SELECT
         ->     CONVERT('₩' USING euckr) AS euckr,
         ->     HEX(CONVERT('₩' USING euckr)) AS hexeuckr;
     +-------+----------+
     | euckr | hexeuckr |
     +-------+----------+
     | ?     | 3F       |
     +-------+----------+
     1 row in set (0.00 sec)

MySQL's graphic Korean chart is here: euckr
(http://www.collation-charts.org/mysql60/by-charset.html#euckr).

*22.11.9: ** ** ** ** Why do I get `Data truncated' error messages?  *

For illustration, we'll create a table with one Unicode (`ucs2') column
and one Chinese (`gb2312') column.

     mysql> CREATE TABLE ch
         -> (ucs2 CHAR(3) CHARACTER SET ucs2,
         -> gb2312 CHAR(3) CHARACTER SET gb2312);
     Query OK, 0 rows affected (0.05 sec)

We'll try to place the rare character `汌' in both columns.

     mysql> INSERT INTO ch VALUES ('A汌B','A汌B');
     Query OK, 1 row affected, 1 warning (0.00 sec)

Ah, there is a warning. Use the following statement to see what it is:

     mysql> SHOW WARNINGS;
     +---------+------+---------------------------------------------+
     | Level   | Code | Message                                     |
     +---------+------+---------------------------------------------+
     | Warning | 1265 | Data truncated for column 'gb2312' at row 1 |
     +---------+------+---------------------------------------------+
     1 row in set (0.00 sec)

So it is a warning about the `gb2312' column only.

     mysql> SELECT ucs2,HEX(ucs2),gb2312,HEX(gb2312) FROM ch;
     +-------+--------------+--------+-------------+
     | ucs2  | HEX(ucs2)    | gb2312 | HEX(gb2312) |
     +-------+--------------+--------+-------------+
     | A汌B | 00416C4C0042 | A?B    | 413F42      |
     +-------+--------------+--------+-------------+
     1 row in set (0.00 sec)

There are several things that need explanation here.

  1. The fact that it is a `warning' rather than an `error' is
     characteristic of MySQL. We like to try to do what we can, to get
     the best fit, rather than give up.

  2. The `汌' character isn't in the `gb2312' character set. We
     described that problem earlier.

  3. Admittedly the message is misleading. We didn't `truncate' in this
     case, we replaced with a question mark. We've had a complaint
     about this message (See Bug#9337 (http://bugs.mysql.com/9337)).
     But until we come up with something better, just accept that
     error/warning code 2165 can mean a variety of things.

  4. With `SQL_MODE=TRADITIONAL', there would be an error message, but
     instead of error 2165 you would see: `ERROR 1406 (22001): Data too
     long for column 'gb2312' at row 1'.

*22.11.10: ** ** ** Why does my GUI front end or browser not display CJK
characters correctly in my application using Access, PHP, or another
API?  *

Obtain a direct connection to the server using the *Note `mysql':
mysql. client (Windows: *Note `mysql.exe': mysql.), and try the same
query there.  If *Note `mysql': mysql. responds correctly, then the
trouble may be that your application interface requires initialization.
Use *Note `mysql': mysql. to tell you what character set or sets it
uses with the statement `SHOW VARIABLES LIKE 'char%';'. If you are
using Access, then you are most likely connecting with MyODBC. In this
case, you should check *Note connector-odbc-configuration::. If, for
instance, you use `big5', you would enter `SET NAMES 'big5''. (Note
that no `;' is required in this case). If you are using ASP, you might
need to add `SET NAMES' in the code. Here is an example that has worked
in the past:

     <%
     Session.CodePage=0
     Dim strConnection
     Dim Conn
     strConnection="driver={MySQL ODBC 3.51 Driver};server=SERVER;uid=USERNAME;" \
                    & "pwd=PASSWORD;database=DATABASE;stmt=SET NAMES 'big5';"
     Set Conn = Server.CreateObject("ADODB.Connection")
     Conn.Open strConnection
     %>

In much the same way, if you are using any character set other than
`latin1' with Connector/NET, then you must specify the character set in
the connection string. See *Note connector-net-using-connecting::, for
more information.

If you are using PHP, try this:

     <?php
       $link = mysql_connect($host, $usr, $pwd);

       mysql_select_db($db);

       if( mysql_error() ) { print "Database ERROR: " . mysql_error(); }
       mysql_query("SET NAMES 'utf8'", $link);
     ?>

In this case, we used `SET NAMES' to change `character_set_client' and
`character_set_connection' and `character_set_results'.

We encourage the use of the newer `mysqli' extension, rather than
`mysql'. Using `mysqli', the previous example could be rewritten as
shown here:

     <?php
       $link = new mysqli($host, $usr, $pwd, $db);

       if( mysqli_connect_errno() )
       {
         printf("Connect failed: %s\n", mysqli_connect_error());
         exit();
       }

       $link->query("SET NAMES 'utf8'");
     ?>

Another issue often encountered in PHP applications has to do with
assumptions made by the browser. Sometimes adding or changing a
`<meta>' tag suffices to correct the problem: for example, to insure
that the user agent interprets page content as `UTF-8', you should
include `<meta http-equiv="Content-Type" content="text/html;
charset=utf-8">' in the `<head>' of the HTML page.

If you are using Connector/J, see *Note
connector-j-reference-charsets::.

*22.11.11: ** ** I've upgraded to MySQL 6.0. How can I revert to
behavior like that in MySQL 4.0 with regard to character sets?  *

In MySQL Version 4.0, there was a single `global' character set for
both server and client, and the decision as to which character to use
was made by the server administrator. This changed starting with MySQL
Version 4.1. What happens now is a `handshake', as described in *Note
charset-connection:::

When a client connects, it sends to the server the name of the
character set that it wants to use. The server uses the name to set the
`character_set_client', `character_set_results', and
`character_set_connection' system variables. In effect, the server
performs a `SET NAMES' operation using the character set name.

The effect of this is that you cannot control the client character set
by starting *Note `mysqld': mysqld. with `--character-set-server=utf8'.
However, some of our Asian customers have said that they prefer the
MySQL 4.0 behavior. To make it possible to retain this behavior, we
added a *Note `mysqld': mysqld. switch,
`--character-set-client-handshake', which can be turned off with
`--skip-character-set-client-handshake'.  If you start *Note `mysqld':
mysqld. with `--skip-character-set-client-handshake', then, when a
client connects, it sends to the server the name of the character set
that it wants to use -- however, _the server ignores this request from
the client_.

By way of example, suppose that your favorite server character set is
`latin1' (unlikely in a CJK area, but this is the default value).
Suppose further that the client uses `utf8' because this is what the
client's operating system supports. Now, start the server with `latin1'
as its default character set:

     mysqld --character-set-server=latin1

And then start the client with the default character set `utf8':

     mysql --default-character-set=utf8

The current settings can be seen by viewing the output of *Note `SHOW
VARIABLES': show-variables.:

     mysql> SHOW VARIABLES LIKE 'char%';
     +--------------------------+----------------------------------------+
     | Variable_name            | Value                                  |
     +--------------------------+----------------------------------------+
     | character_set_client     | utf8                                   |
     | character_set_connection | utf8                                   |
     | character_set_database   | latin1                                 |
     | character_set_filesystem | binary                                 |
     | character_set_results    | utf8                                   |
     | character_set_server     | latin1                                 |
     | character_set_system     | utf8                                   |
     | character_sets_dir       | /usr/local/mysql/share/mysql/charsets/ |
     +--------------------------+----------------------------------------+
     8 rows in set (0.01 sec)

Now stop the client, and then stop the server using *Note `mysqladmin':
mysqladmin. Then start the server again, but this time tell it to skip
the handshake like so:

     mysqld --character-set-server=utf8 --skip-character-set-client-handshake

Start the client with `utf8' once again as the default character set,
then display the current settings:

     mysql> SHOW VARIABLES LIKE 'char%';
     +--------------------------+----------------------------------------+
     | Variable_name            | Value                                  |
     +--------------------------+----------------------------------------+
     | character_set_client     | latin1                                 |
     | character_set_connection | latin1                                 |
     | character_set_database   | latin1                                 |
     | character_set_filesystem | binary                                 |
     | character_set_results    | latin1                                 |
     | character_set_server     | latin1                                 |
     | character_set_system     | utf8                                   |
     | character_sets_dir       | /usr/local/mysql/share/mysql/charsets/ |
     +--------------------------+----------------------------------------+
     8 rows in set (0.01 sec)

As you can see by comparing the differing results from *Note `SHOW
VARIABLES': show-variables, the server ignores the client's initial
settings if the `--skip-character-set-client-handshake' is used.

*22.11.12: ** ** ** Why do some `LIKE' and `FULLTEXT' searches with CJK
characters fail?  *

There is a very simple problem with `LIKE' searches on *Note `BINARY':
binary-varbinary. and *Note `BLOB': blob. columns: we need to know the
end of a character. With multi-byte character sets, different
characters might have different octet lengths. For example, in `utf8',
`A' requires one byte but `ペ' requires three bytes, as shown here:

     +-------------------------+---------------------------+
     | OCTET_LENGTH(_utf8 'A') | OCTET_LENGTH(_utf8 'ペ') |
     +-------------------------+---------------------------+
     |                       1 |                         3 |
     +-------------------------+---------------------------+
     1 row in set (0.00 sec)

If we don't know where the first character ends, then we don't know
where the second character begins, in which case even very simple
searches such as `LIKE '_A%'' fail. The solution is to use a regular
CJK character set in the first place, or to convert to a CJK character
set before comparing.

This is one reason why MySQL cannot allow encodings of non-existent
characters. If it is not strict about rejecting bad input, then it has
no way of knowing where characters end.

For `FULLTEXT' searches, we need to know where words begin and end.
With Western languages, this is rarely a problem because most (if not
all) of these use an easy-to-identify word boundary -- the space
character.  However, this is not usually the case with Asian writing. We
could use arbitrary halfway measures, like assuming that all Han
characters represent words, or (for Japanese) depending on changes from
Katakana to Hiragana due to grammatical endings. However, the only sure
solution requires a comprehensive word list, which means that we would
have to include a dictionary in the server for each Asian language
supported. This is simply not feasible.

*22.11.13: ** ** ** How do I know whether character X is available in
all character sets?  *

The majority of simplified Chinese and basic non-halfwidth Japanese
_Kana_ characters appear in all CJK character sets. This stored
procedure accepts a `UCS-2' Unicode character, converts it to all other
character sets, and displays the results in hexadecimal.

     DELIMITER //

     CREATE PROCEDURE p_convert(ucs2_char CHAR(1) CHARACTER SET ucs2)
     BEGIN

     CREATE TABLE tj
                  (ucs2 CHAR(1) character set ucs2,
                   utf8 CHAR(1) character set utf8,
                   big5 CHAR(1) character set big5,
                   cp932 CHAR(1) character set cp932,
                   eucjpms CHAR(1) character set eucjpms,
                   euckr CHAR(1) character set euckr,
                   gb2312 CHAR(1) character set gb2312,
                   gbk CHAR(1) character set gbk,
                   sjis CHAR(1) character set sjis,
                   ujis CHAR(1) character set ujis);

     INSERT INTO tj (ucs2) VALUES (ucs2_char);

     UPDATE tj SET utf8=ucs2,
                   big5=ucs2,
                   cp932=ucs2,
                   eucjpms=ucs2,
                   euckr=ucs2,
                   gb2312=ucs2,
                   gbk=ucs2,
                   sjis=ucs2,
                   ujis=ucs2;

     /* If there is a conversion problem, UPDATE will produce a warning. */

     SELECT hex(ucs2) AS ucs2,
            hex(utf8) AS utf8,
            hex(big5) AS big5,
            hex(cp932) AS cp932,
            hex(eucjpms) AS eucjpms,
            hex(euckr) AS euckr,
            hex(gb2312) AS gb2312,
            hex(gbk) AS gbk,
            hex(sjis) AS sjis,
            hex(ujis) AS ujis
     FROM tj;

     DROP TABLE tj;

     END//

The input can be any single `ucs2' character, or it can be the code
point value (hexadecimal representation) of that character. For
example, from Unicode's list of `ucs2' encodings and names
(`http://www.unicode.org/Public/UNIDATA/UnicodeData.txt'), we know that
the _Katakana_ character _Pe_ appears in all CJK character sets, and
that its code point value is `0x30da'. If we use this value as the
argument to `p_convert()', the result is as shown here:

     mysql> CALL p_convert(0x30da)//
     +------+--------+------+-------+---------+-------+--------+------+------+------+
     | ucs2 | utf8   | big5 | cp932 | eucjpms | euckr | gb2312 | gbk  | sjis | ujis |
     +------+--------+------+-------+---------+-------+--------+------+------+------+
     | 30DA | E3839A | C772 | 8379  | A5DA    | ABDA  | A5DA   | A5DA | 8379 | A5DA |
     +------+--------+------+-------+---------+-------+--------+------+------+------+
     1 row in set (0.04 sec)

Since none of the column values is `3F' -- that is, the question mark
character (`?') -- we know that every conversion worked.

*22.11.14: ** ** ** ** ** Why don't CJK strings sort correctly in
Unicode? (I) *

Sometimes people observe that the result of a `utf8_unicode_ci' or
`ucs2_unicode_ci' search, or of an `ORDER BY' sort is not what they
think a native would expect. Although we never rule out the possibility
that there is a bug, we have found in the past that many people do not
read correctly the standard table of weights for the Unicode Collation
Algorithm. MySQL uses the table found at
`http://www.unicode.org/Public/UCA/4.0.0/allkeys-4.0.0.txt'.  This is
not the first table you will find by navigating from the `unicode.org'
home page, because MySQL uses the older 4.0.0 `allkeys' table, rather
than the more recent 4.1.0 table. This is because we are very wary
about changing ordering which affects indexes, lest we bring about
situations such as that reported in Bug#16526
(http://bugs.mysql.com/16526), illustrated as follows:

     mysql< CREATE TABLE tj (s1 CHAR(1) CHARACTER SET utf8 COLLATE utf8_unicode_ci);
     Query OK, 0 rows affected (0.05 sec)

     mysql> INSERT INTO tj VALUES ('が'),('か');
     Query OK, 2 rows affected (0.00 sec)
     Records: 2  Duplicates: 0  Warnings: 0

     mysql> SELECT * FROM tj WHERE s1 = 'か';
     +------+
     | s1   |
     +------+
     | が  |
     | か  |
     +------+
     2 rows in set (0.00 sec)

The character in the first result row is not the one that we searched
for. Why did MySQL retrieve it? First we look for the Unicode code
point value, which is possible by reading the hexadecimal number for
the `ucs2' version of the characters:

     mysql> SELECT s1, HEX(CONVERT(s1 USING ucs2)) FROM tj;
     +------+-----------------------------+
     | s1   | HEX(CONVERT(s1 USING ucs2)) |
     +------+-----------------------------+
     | が  | 304C                        |
     | か  | 304B                        |
     +------+-----------------------------+
     2 rows in set (0.03 sec)

Now we search for `304B' and `304C' in the `4.0.0 allkeys' table, and
find these lines:

     304B  ; [.1E57.0020.000E.304B] # HIRAGANA LETTER KA
     304C  ; [.1E57.0020.000E.304B][.0000.0140.0002.3099] # HIRAGANA LETTER GA; QQCM

The official Unicode names (following the `#' mark) tell us the
Japanese syllabary (Hiragana), the informal classification (letter,
digit, or punctuation mark), and the Western identifier (`KA' or `GA',
which happen to be voiced and unvoiced components of the same letter
pair). More importantly, the _primary weight_ (the first hexadecimal
number inside the square brackets) is `1E57' on both lines. For
comparisons in both searching and sorting, MySQL pays attention to the
primary weight only, ignoring all the other numbers. This means that we
are sorting `が' and `か' correctly according to the Unicode
specification. If we wanted to distinguish them, we'd have to use a
non-UCA (Unicode Collation Algorithm) collation (`utf8_bin' or
`utf8_general_ci'), or to compare the `HEX()' values, or use `ORDER BY
CONVERT(s1 USING sjis)'. Being correct `according to Unicode' isn't
enough, of course: the person who submitted the bug was equally
correct. We plan to add another collation for Japanese according to the
JIS X 4061 standard, in which voiced/unvoiced letter pairs like
`KA'/`GA' are distinguishable for ordering purposes.

*22.11.15: ** ** ** ** ** ** Why don't CJK strings sort correctly in
Unicode? (II) *

If you are using Unicode (`ucs2' or `utf8'), and you know what the
Unicode sort order is (see *Note faqs-cjk::), but MySQL still seems to
sort your table incorrectly, then you should first verify the table
character set:

     mysql> SHOW CREATE TABLE t\G
     ******************** 1. row ******************
     Table: t
     Create Table: CREATE TABLE `t` (
     `s1` char(1) CHARACTER SET ucs2 DEFAULT NULL
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1
     1 row in set (0.00 sec)

Since the character set appears to be correct, let's see what
information the *Note `INFORMATION_SCHEMA.COLUMNS': columns-table.
table can provide about this column:

     mysql> SELECT COLUMN_NAME, CHARACTER_SET_NAME, COLLATION_NAME
         -> FROM INFORMATION_SCHEMA.COLUMNS
         -> WHERE COLUMN_NAME = 's1'
         -> AND TABLE_NAME = 't';
     +-------------+--------------------+-----------------+
     | COLUMN_NAME | CHARACTER_SET_NAME | COLLATION_NAME  |
     +-------------+--------------------+-----------------+
     | s1          | ucs2               | ucs2_general_ci |
     +-------------+--------------------+-----------------+
     1 row in set (0.01 sec)

(See *Note columns-table::, for more information.)

You can see that the collation is `ucs2_general_ci' instead of
`ucs2_unicode_ci'. The reason why this is so can be found using `SHOW
CHARSET', as shown here:

     mysql> SHOW CHARSET LIKE 'ucs2%';
     +---------+---------------+-------------------+--------+
     | Charset | Description   | Default collation | Maxlen |
     +---------+---------------+-------------------+--------+
     | ucs2    | UCS-2 Unicode | ucs2_general_ci   |      2 |
     +---------+---------------+-------------------+--------+
     1 row in set (0.00 sec)

For `ucs2' and `utf8', the default collation is `general'. To specify a
Unicode collation, use `COLLATE ucs2_unicode_ci'.

*22.11.16: ** ** Why are my supplementary characters rejected by MySQL?
*

Before MySQL 6.0.4, MySQL does not support supplementary characters --
that is, characters which need more than 3 bytes -- for `UTF-8'. We
support only what Unicode calls the _Basic Multilingual Plane / Plane
0_. Only a few very rare Han characters are supplementary; support for
them is uncommon.  This has led to reports such as that found in
Bug#12600 (http://bugs.mysql.com/12600), which we rejected as `not a
bug'. With `utf8', we must truncate an input string when we encounter
bytes that we don't understand. Otherwise, we wouldn't know how long
the bad multi-byte character is.

One possible workaround is to use `ucs2' instead of `utf8', in which
case the `bad' characters are changed to question marks; however, no
truncation takes place. You can also change the data type to *Note
`BLOB': blob. or *Note `BINARY': binary-varbinary, which perform no
validity checking.

As of MySQL 6.0.4, Unicode support is extended to include supplementary
characters by means of additional Unicode character sets: `utf16',
`utf32', and 4-byte `utf8'. These character sets support supplementary
Unicode characters outside the Basic Multilingual Plane (BMP).

*22.11.17: ** ** ** ** Shouldn't it be `CJKV'?  *

No. The term `CJKV' (_Chinese Japanese Korean Vietnamese_) refers to
Vietnamese character sets which contain Han (originally Chinese)
characters. MySQL has no plan to support the old Vietnamese script
using Han characters. MySQL does of course support the modern
Vietnamese script with Western characters.

Bug#4745 (http://bugs.mysql.com/4745) is a request for a specialized
Vietnamese collation, which we might add in the future if there is
sufficient demand for it.

*22.11.18: ** ** Does MySQL allow CJK characters to be used in database
and table names?  *

This issue was fixed in MySQL 5.1, by automatically rewriting the names
of the corresponding directories and files.

For example, if you create a database named `楮' on a server whose
operating system does not support CJK in directory names, MySQL creates
a directory named `@0w@00a5@00ae'. which is just a fancy way of
encoding `E6A5AE' -- that is, the Unicode hexadecimal representation for
the `楮' character. However, if you run a *Note `SHOW DATABASES':
show-databases. statement, you can see that the database is listed as
`楮'.

*22.11.19: ** ** ** ** ** ** **** Where can I find translations of the
MySQL Manual into Chinese, Japanese, and Korean?  *

A Simplified Chinese version of the Manual, current for MySQL 5.1.12,
can be found at `http://dev.mysql.com/doc/'. The Japanese translation
of the MySQL 4.1 manual can be downloaded from
`http://dev.mysql.com/doc/'.

*22.11.20: ** Where can I get help with CJK and related issues in MySQL?
*

The following resources are available:

   * A listing of MySQL user groups can be found at
     `http://dev.mysql.com/user-groups/'.

   * You can contact a sales engineer at the MySQL KK Japan office
     using any of the following:

          Tel: +81(0)3-5326-3133
          Fax: +81(0)3-5326-3001
          Email: dsaito@mysql.com

   * View feature requests relating to character set issues at
     `http://tinyurl.com/y6xcuf'.

   * Visit the MySQL Collation Unicode Forum. We are also in the
     process of adding foreign-language forums at
     `http://forums.mysql.com/'.


File: manual.info,  Node: faqs-connectors-apis,  Next: faqs-replication,  Prev: faqs-cjk,  Up: faqs

A.12 MySQL 6.0 FAQ -- Connectors & APIs
=======================================

For common questions, issues, and answers relating to the MySQL
Connectors and other APIs, see the following areas of the Manual:

   * *Note c-api-problems::

   * *Note apis-php-problems::

   * *Note connector-odbc-usagenotes::

   * *Note connector-net-using::

   * *Note connector-j-usagenotes::

   * *Note connector-mxj-usagenotes::


File: manual.info,  Node: faqs-replication,  Next: faqs-mysql-drbd-heartbeat,  Prev: faqs-connectors-apis,  Up: faqs

A.13 MySQL 6.0 FAQ -- Replication
=================================

For answers to common queries and question regarding Replication within
MySQL, see *Note replication-faq::.


File: manual.info,  Node: faqs-mysql-drbd-heartbeat,  Prev: faqs-replication,  Up: faqs

A.14 MySQL 6.0 FAQ -- MySQL, DRBD, and Heartbeat
================================================

* Menu:

* faqs-drbd::                    Distributed Replicated Block Device (DRBD) Basics
* drbd-linux-heartbeat::         Linux Heartbeat
* drbd-architecture::            DRBD Architecture
* drbd-mysql-replication-scale::  DRBD and MySQL Replication
* drbd-file-systems::            DRBD and File Systems
* drbd-lvm::                     DRBD and LVM
* drbd-virtualization::          DRBD and Virtualization
* drbd-security::                DRBD and Security
* drbd-system-requirements::     DRBD and System Requirements
* drbd-support-consulting::      DBRD and Support and Consulting


File: manual.info,  Node: faqs-drbd,  Next: drbd-linux-heartbeat,  Prev: faqs-mysql-drbd-heartbeat,  Up: faqs-mysql-drbd-heartbeat

A.14.1 Distributed Replicated Block Device (DRBD) Basics
--------------------------------------------------------

In the following section, we provide answers to questions that are most
frequently asked about Distributed Replicated Block Device (DRBD).

*Questions*
   * 22.14.1.1: 

     What is DRBD?

   * 22.14.1.2: What are `Block Devices'?

   * 22.14.1.3: 

     How is DRBD licensed?

   * 22.14.1.4: Where can I download DRBD?

   * 22.14.1.5: If I find a bug in DRBD, to whom do I submit the issue?

   * 22.14.1.6: Where can I get more technical and business information
     concerning MySQL and DRBD?

*Questions and Answers* *22.14.1.1: ** ** What is DRBD?  *

DRBD is an acronym for Distributed Replicated Block Device. DRBD is an
open source Linux kernel block device which leverages synchronous
replication to achieve a consistent view of data between two systems,
typically an Active and Passive system. DRBD currently supports all the
major flavors of Linux and comes bundled in several major Linux
distributions. The DRBD project is maintained by LINBIT
(http://www.drbd.org/).

*22.14.1.2: ** What are `Block Devices'?  *

A _block device_ is the type of device used to represent storage in the
Linux Kernel. All physical disk devices present a block device
interface.  Additionally, virtual disk systems like LVM or DRBD present
a block device interface. In this way, the file system or other
software that might want to access a disk device can be used with any
number of real or virtual devices without having to know anything about
their underlying implementation details.

*22.14.1.3: ** ** How is DRBD licensed?  *

DRBD is licensed under the GPL.

*22.14.1.4: ** Where can I download DRBD?  *

Please see `http://www.drbd.org/download/packages/'.

*22.14.1.5: ** If I find a bug in DRBD, to whom do I submit the issue?
*

Bug reports should be submitted to the DRBD mailing list.  Please see
`http://lists.linbit.com/'.

*22.14.1.6: ** Where can I get more technical and business information
concerning MySQL and DRBD?  *

Please visit `http://mysql.com/drbd/'.


File: manual.info,  Node: drbd-linux-heartbeat,  Next: drbd-architecture,  Prev: faqs-drbd,  Up: faqs-mysql-drbd-heartbeat

A.14.2 Linux Heartbeat
----------------------

In the following section, we provide answers to questions that are most
frequently asked about Linux Heartbeat.

*Questions*
   * 22.14.2.1: What is Linux Heartbeat?

   * 22.14.2.2: How is Linux Heartbeat licensed?

   * 22.14.2.3: Where can I download Linux Heartbeat?

   * 22.14.2.4: If I find a bug with Linux Heartbeat, to whom do I
     submit the issue?

*Questions and Answers* *22.14.2.1: ** What is Linux Heartbeat?  *

The Linux-HA project (`http://www.linux-ha.org/') offers a high
availability solution commonly referred to as Linux Heartbeat. Linux
Heartbeat ships as part of several Linux distributions, as well as
within several embedded high availability systems. This solution can
also be used for other applications besides databases servers, such as
mail servers, web servers, file servers, and DNS servers.

Linux Heartbeat implements a heartbeat-protocol. A heartbeat-protocol
means that messages are sent at regular intervals between two or more
nodes. If a message is not received from a node within a given
interval, then it is assumed the node has failed and some type of
failover or recovery action is required. Linux Heartbeat is typically
configured to send these heartbeat messages over standard Ethernet
interfaces, but it does also support other methods, such as serial-line
links.

*22.14.2.2: ** How is Linux Heartbeat licensed?  *

Linux Heartbeat is licensed under the GPL.

*22.14.2.3: ** Where can I download Linux Heartbeat?  *

Please see `http://linux-ha.org/download/index.html'.

*22.14.2.4: ** If I find a bug with Linux Heartbeat, to whom do I submit
the issue?  *

Bug reports should be submitted to
`http://www.linux-ha.org/ClusterResourceManager/BugReports'.


File: manual.info,  Node: drbd-architecture,  Next: drbd-mysql-replication-scale,  Prev: drbd-linux-heartbeat,  Up: faqs-mysql-drbd-heartbeat

A.14.3 DRBD Architecture
------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD Architecture.

*Questions*
   * 22.14.3.1: Is an Active/Active option available for MySQL with
     DRBD?

   * 22.14.3.2: What MySQL storage engines are supported with DRBD?

   * 22.14.3.3: How long does a failover take?

   * 22.14.3.4: How long does it take to resynchronize data after a
     failure?

   * 22.14.3.5: Are there any situations where you shouldn't use DRBD?

   * 22.14.3.6: Are there any limitations to DRBD?

   * 22.14.3.7: Where can I find more information on sample
     architectures?

*Questions and Answers* *22.14.3.1: ** Is an Active/Active option
available for MySQL with DRBD?  *

Currently, MySQL does not support Active/Active configurations using
DRBD `out of the box'.

*22.14.3.2: ** What MySQL storage engines are supported with DRBD?  *

All of the MySQL transactional storage engines are supported by DRBD,
including InnoDB and Falcon. For archived or read-only data, MyISAM or
Archive can also be used.

*22.14.3.3: ** How long does a failover take?  *

Failover time is dependent on many things, some of which are
configurable. After activating the passive host, MySQL will have to
start and run a normal recovery process. If the InnoDB log files have
been configured to a large size and there was heavy write traffic, this
may take a reasonably long period of time. However, under normal
circumstances, failover tends to take less than a minute.

*22.14.3.4: ** How long does it take to resynchronize data after a
failure?  *

Resynchronization time depends on how long the two machines are out of
communication and how much data was written during that period of time.
Resynchronization time is a function of data to be synced, network
speed and disk speed. DRBD maintains a bitmap of changed blocks on the
primary machine, so only those blocks that have changed will need to be
transferred.

*22.14.3.5: ** Are there any situations where you shouldn't use DRBD?  *

See When Not To Use DRBD
(http://fghaas.wordpress.com/2007/06/26/when-not-to-use-drbd/).

*22.14.3.6: ** Are there any limitations to DRBD?  *

See DRBD limitations (or are they?)
(http://fghaas.wordpress.com/2007/06/18/drbd-limitations-or-are-they/).

*22.14.3.7: ** Where can I find more information on sample
architectures?  *

For an example of a Heartbeat R1-compatible resource configuration
involving a MySQL database backed by DRBD, see DRBD User's Guide
(http://www.drbd.org/users-guide/s-heartbeat-r1.html).

For an example of the same DRBD-backed configuration for a MySQL
database in a Heartbeat CRM cluster, see DRBD User's Guide
(http://www.drbd.org/users-guide/s-heartbeat-crm.html).


File: manual.info,  Node: drbd-mysql-replication-scale,  Next: drbd-file-systems,  Prev: drbd-architecture,  Up: faqs-mysql-drbd-heartbeat

A.14.4 DRBD and MySQL Replication
---------------------------------

In the following section, we provide answers to questions that are most
frequently asked about MySQL Replication Scale-out.

*Questions*
   * 22.14.4.1: What is the difference between MySQL Cluster and DRBD?

   * 22.14.4.2: What is the difference between MySQL Replication and
     DRBD?

   * 22.14.4.3: How can I combine MySQL Replication scale-out with DRBD?

*Questions and Answers* *22.14.4.1: ** What is the difference between
MySQL Cluster and DRBD?  *

Both MySQL Cluster and DRBD replicate data synchronously.  MySQL
Cluster leverages a shared-nothing storage architecture in which the
cluster can be architected beyond an Active/Passive configuration. DRBD
operates at a much lower level within the `stack', at the disk I/O
level. For a comparison of various high availability features between
these two options, please refer to *Note ha-overview::.

*Note*:

MySQL Cluster is currently not supported in MySQL 6.0.  If you are
interested in using MySQL Cluster, see MySQL Cluster NDB 6.X/7.X
(http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster.html), which
provides information about MySQL Cluster NDB 6.2 and 6.3 (based on
MySQL 5.1 but containing the latest improvements and fixes for the
`NDBCLUSTER' storage engine).

*22.14.4.2: ** What is the difference between MySQL Replication and
DRBD?  *

MySQL Replication replicates data asynchronously while DRBD replicates
data synchronously. Also, MySQL Replication replicates MySQL
statements, while DRBD replicates the underlying block device that
stores the MySQL data files. For a comparison of various high
availability features between these two options, please refer to the
high availability comparison grid, *Note ha-overview::.

*22.14.4.3: ** How can I combine MySQL Replication scale-out with DRBD?
*

MySQL Replication is typically deployed in a Master to many Slaves
configuration. In this configuration, having many Slaves provides read
scalability. DRBD is used to provide high-availability for the Master
MySQL Server in an Active/Passive configuration. This provides for
automatic failover, safeguards against data loss, and automatically
synchronizes the failed MySQL Master after a failover.

The most likely scenario in which MySQL Replication scale-out can be
leveraged with DRBD is in the form of attaching replicated MySQL
`read-slaves' off of the Active-Master MySQL Server, shown in *Note
active-master-mysql-server::. Since DRBD replicates an entire block
device, master information such as the binary logs are also replicated.
In this way, all of the slaves can attach to the Virtual IP Address
managed by Linux Heartbeat. In the event of a failure, the asynchronous
nature of MySQL Replication allows the slaves to continue with the new
Active machine as their master with no intervention needed.

FIGURE GOES HERE: Active-Master MySQL server


File: manual.info,  Node: drbd-file-systems,  Next: drbd-lvm,  Prev: drbd-mysql-replication-scale,  Up: faqs-mysql-drbd-heartbeat

A.14.5 DRBD and File Systems
----------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and file systems.

*Questions*
   * 22.14.5.1: Can XFS be used with DRBD?

*Questions and Answers* *22.14.5.1: ** Can XFS be used with DRBD?  *

Yes. XFS uses dynamic block size, thus DRBD 0.7 or later is needed.


File: manual.info,  Node: drbd-lvm,  Next: drbd-virtualization,  Prev: drbd-file-systems,  Up: faqs-mysql-drbd-heartbeat

A.14.6 DRBD and LVM
-------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and LVM.

*Questions*
   * 22.14.6.1: Can I use DRBD on top of LVM?

   * 22.14.6.2: Can I use LVM on top of DRBD?

   * 22.14.6.3: Can I use DRBD on top of LVM while at the same time
     running LVM on top of that DRBD?

*Questions and Answers* *22.14.6.1: ** Can I use DRBD on top of LVM?  *

Yes, DRBD supports on-line resizing. If you enlarge your logical volume
that acts as a backing device for DRBD, you can enlarge DRBD itself
too, and of course your file system if it supports resizing.

*22.14.6.2: ** Can I use LVM on top of DRBD?  *

Yes, you can use DRBD as a Physical Volume (PV) for LVM.  Depending on
the default LVM configuration shipped with your distribution, you may
need to add the `/dev/drbd*' device files to the `filter' option in your
`lvm.conf' so LVM scans your DRBDs for PV signatures.

*22.14.6.3: ** Can I use DRBD on top of LVM while at the same time
running LVM on top of that DRBD?  *

This requires careful tuning of your LVM configuration to avoid
duplicate PV scans, but yes, it is possible.


File: manual.info,  Node: drbd-virtualization,  Next: drbd-security,  Prev: drbd-lvm,  Up: faqs-mysql-drbd-heartbeat

A.14.7 DRBD and Virtualization
------------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and virtualization.

*Questions*
   * 22.14.7.1: Can I use DRBD with OpenVZ?

   * 22.14.7.2: Can I use DRBD with Xen and/or KVM?

*Questions and Answers* *22.14.7.1: ** Can I use DRBD with OpenVZ?  *

See `http://wiki.openvz.org/HA_cluster_with_DRBD_and_Heartbeat'.

*22.14.7.2: ** Can I use DRBD with Xen and/or KVM?  *

Yes. If you are looking for professional consultancy or expert
commercial support for Xen- or KVM-based virtualization clusters with
DRBD, contact LINBIT (`http://www.linbit.com').


File: manual.info,  Node: drbd-security,  Next: drbd-system-requirements,  Prev: drbd-virtualization,  Up: faqs-mysql-drbd-heartbeat

A.14.8 DRBD and Security
------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and security.

*Questions*
   * 22.14.8.1: Can I encrypt/compress the exchanged data?

   * 22.14.8.2: Does DRBD do mutual node authentication?

*Questions and Answers* *22.14.8.1: ** Can I encrypt/compress the
exchanged data?  *

Yes. But there is no option within DRBD to allow for this.  You'll need
to leverage a VPN and the network layer should do the rest.

*22.14.8.2: ** Does DRBD do mutual node authentication?  *

Yes, starting with DRBD 8 shared-secret mutual node authentication is
supported.


File: manual.info,  Node: drbd-system-requirements,  Next: drbd-support-consulting,  Prev: drbd-security,  Up: faqs-mysql-drbd-heartbeat

A.14.9 DRBD and System Requirements
-----------------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and System Requirements.

*Questions*
   * 22.14.9.1: What other packages besides DRBD are required?

   * 22.14.9.2: How many machines are required to set up DRBD?

   * 22.14.9.3: Does DRBD only run on Linux?

*Questions and Answers* *22.14.9.1: ** What other packages besides DRBD
are required?  *

When using pre-built binary packages, none except a matching kernel,
plus packages for `glibc' and your favorite shell. When compiling DRBD
from source additional prerequisite packages may be required. They
include but are not limited to:

   * glib-devel

   * openssl

   * devel

   * libgcrypt-devel

   * glib2-devel

   * pkgconfig

   * ncurses-devel

   * rpm-build

   * rpm-devel

   * redhat-rpm-config

   * gcc

   * gcc-c++

   * bison

   * flex

   * gnutls-devel

   * lm_sensors-devel

   * net-snmp-devel

   * python-devel

   * bzip2-devel

   * libselinux-devel

   * perl-DBI

   * libnet

Pre-built x86 and x86_64 packages for specific kernel versions are
available with a support subscription from LINBIT. Please note that if
the kernel is upgraded, DRBD must be as well.

*22.14.9.2: ** How many machines are required to set up DRBD?  *

Two machines are required to achieve the minimum degree of high
availability. Although at any one given point in time one will be
primary and one will be secondary, it is better to consider the
machines as part of a mirrored pair without a `natural' primary machine.

*22.14.9.3: ** Does DRBD only run on Linux?  *

DRBD is a Linux Kernel Module, and can work with many popular Linux
distributions. DRBD is currently not available for non-Linux operating
systems.


File: manual.info,  Node: drbd-support-consulting,  Prev: drbd-system-requirements,  Up: faqs-mysql-drbd-heartbeat

A.14.10 DBRD and Support and Consulting
---------------------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and resources.

*Questions*
   * 22.14.10.1: Does MySQL offer professional consulting to help with
     designing a DRBD system?

   * 22.14.10.2: Does MySQL offer support for DRBD and Linux Heartbeat
     from MySQL?

   * 22.14.10.3: Are pre-built binaries or RPMs available?

   * 22.14.10.4: Does MySQL have documentation to help me with the
     installation and configuration of DRBD and Linux Heartbeat?

   * 22.14.10.5: Is there a dedicated discussion forum for MySQL
     High-Availability?

   * 22.14.10.6: Where can I get more information about MySQL for DRBD?

*Questions and Answers* *22.14.10.1: ** Does MySQL offer professional
consulting to help with designing a DRBD system?  *

Yes. MySQL offers consulting for the design, installation,
configuration, and monitoring of high availability DRBD.  For more
information concerning a High Availability Jumpstart, please see:
`http://www.mysql.com/consulting/packaged/scaleout.html'.

*22.14.10.2: ** Does MySQL offer support for DRBD and Linux Heartbeat
from MySQL?  *

Yes. Support for DRBD and Linux Heartbeat is available with an add-on
subscription to MySQL Enterprise called `DRBD for MySQL'. For more
information about support options for DRBD see:
`http://mysql.com/products/enterprise/features.html'.

For the list of supported Linux distributions, please see:
`http://www.mysql.com/support/supportedplatforms/enterprise.html'.

*Note*:

DRBD is only available on Linux. DRBD is not available on Windows,
MacOS, Solaris, HPUX, AIX, FreeBSD, or other non-Linux platforms.

*22.14.10.3: ** Are pre-built binaries or RPMs available?  *

Yes. `DRBD for MySQL' is an add-on subscription to MySQL Enterprise,
which provides pre-built binaries for DRBD. For more information, see:
`http://mysql.com/products/enterprise/features.html'.

*22.14.10.4: ** Does MySQL have documentation to help me with the
installation and configuration of DRBD and Linux Heartbeat?  *

For MySQL-specific DRBD documentation, see *Note ha-drbd::.

For general DRBD documentation, see DRBD User's Guide
(http://www.drbd.org/users-guide/).

*22.14.10.5: ** Is there a dedicated discussion forum for MySQL
High-Availability?  *

Yes, `http://forums.mysql.com/list.php?144'.

*22.14.10.6: ** Where can I get more information about MySQL for DRBD?
*

For more information about MySQL for DRBD, including a technical white
paper please see: DRBD for MySQL High Availability
(http://www.mysql.com/products/enterprise/drbd.html).


File: manual.info,  Node: error-handling,  Next: news,  Prev: faqs,  Up: Top

Appendix B Errors, Error Codes, and Common Problems
***************************************************

* Menu:

* problems::                     Problems and Common Errors
* error-types::                  Types of Error Values
* error-messages-server::        Server Error Codes and Messages
* error-messages-client::        Client Error Codes and Messages

This appendix lists common problems and errors that may occur and
potential resolutions, in addition to listing the errors that may
appear when you call MySQL from any host language. The first section
covers problems and resolutions. Detailed information on errors is
provided; The first list displays server error messages. The second
list displays client program messages.

MySQL Enterprise

The MySQL Enterprise Monitor provides a `Virtual DBA' to assist with
problem solving. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: problems,  Next: error-types,  Prev: error-handling,  Up: error-handling

B.1 Problems and Common Errors
==============================

* Menu:

* what-is-crashing::             How to Determine What Is Causing a Problem
* common-errors::                Common Errors When Using MySQL Programs
* installation-issues::          Installation-Related Issues
* administration-issues::        Administration-Related Issues
* query-issues::                 Query-Related Issues
* optimizer-issues::             Optimizer-Related Issues
* table-definition-issues::      Table Definition-Related Issues
* bugs::                         Known Issues in MySQL

This section lists some common problems and error messages that you may
encounter. It describes how to determine the causes of the problems and
what to do to solve them.


File: manual.info,  Node: what-is-crashing,  Next: common-errors,  Prev: problems,  Up: problems

B.1.1 How to Determine What Is Causing a Problem
------------------------------------------------

When you run into a problem, the first thing you should do is to find
out which program or piece of equipment is causing it:

   * If you have one of the following symptoms, then it is probably a
     hardware problems (such as memory, motherboard, CPU, or hard disk)
     or kernel problem:

        * The keyboard doesn't work. This can normally be checked by
          pressing the Caps Lock key. If the Caps Lock light doesn't
          change, you have to replace your keyboard.  (Before doing
          this, you should try to restart your computer and check all
          cables to the keyboard.)

        * The mouse pointer doesn't move.

        * The machine doesn't answer to a remote machine's pings.

        * Other programs that are not related to MySQL don't behave
          correctly.

        * Your system restarted unexpectedly. (A faulty user-level
          program should never be able to take down your system.)

     In this case, you should start by checking all your cables and run
     some diagnostic tool to check your hardware! You should also check
     whether there are any patches, updates, or service packs for your
     operating system that could likely solve your problem. Check also
     that all your libraries (such as `glibc') are up to date.

     It is always good to use a machine with ECC memory to discover
     memory problems early.

   * If your keyboard is locked up, you may be able to recover by
     logging in to your machine from another machine and executing
     `kbd_mode -a'.

   * Please examine your system log file (`/var/log/messages' or
     similar) for reasons for your problem. If you think the problem is
     in MySQL, you should also examine MySQL's log files. See *Note
     server-logs::.

   * If you don't think you have hardware problems, you should try to
     find out which program is causing problems. Try using `top', `ps',
     Task Manager, or some similar program, to check which program is
     taking all CPU or is locking the machine.

   * Use `top', `df', or a similar program to check whether you are out
     of memory, disk space, file descriptors, or some other critical
     resource.

   * If the problem is some runaway process, you can always try to kill
     it. If it doesn't want to die, there is probably a bug in the
     operating system.

If after you have examined all other possibilities and you have
concluded that the MySQL server or a MySQL client is causing the
problem, it is time to create a bug report for our mailing list or our
support team. In the bug report, try to give a very detailed
description of how the system is behaving and what you think is
happening. You should also state why you think that MySQL is causing
the problem. Take into consideration all the situations in this
chapter. State any problems exactly how they appear when you examine
your system. Use the `copy and paste' method for any output and error
messages from programs and log files.

Try to describe in detail which program is not working and all symptoms
you see. We have in the past received many bug reports that state only
`the system doesn't work.' This doesn't provide us with any information
about what could be the problem.

If a program fails, it is always useful to know the following
information:

   * Has the program in question made a segmentation fault (did it dump
     core)?

   * Is the program taking up all available CPU time? Check with `top'.
     Let the program run for a while, it may simply be evaluating
     something computationally intensive.

   * If the *Note `mysqld': mysqld. server is causing problems, can you
     get any response from it with *Note `mysqladmin -u root ping':
     mysqladmin. or *Note `mysqladmin -u root processlist': mysqladmin.?

   * What does a client program say when you try to connect to the
     MySQL server? (Try with *Note `mysql': mysql, for example.) Does
     the client jam? Do you get any output from the program?

When sending a bug report, you should follow the outline described in
*Note bug-reports::.


File: manual.info,  Node: common-errors,  Next: installation-issues,  Prev: what-is-crashing,  Up: problems

B.1.2 Common Errors When Using MySQL Programs
---------------------------------------------

* Menu:

* error-access-denied::          `Access denied'
* can-not-connect-to-server::    `Can't connect to [local] MySQL server'
* error-lost-connection::        `Lost connection to MySQL server'
* old-client::                   `Client does not support authentication protocol'
* password-too-long::            Password Fails When Entered Interactively
* blocked-host::                 `Host 'HOST_NAME' is blocked'
* too-many-connections::         `Too many connections'
* out-of-memory::                `Out of memory'
* gone-away::                    `MySQL server has gone away'
* packet-too-large::             `Packet too large'
* communication-errors::         Communication Errors and Aborted Connections
* full-table::                   `The table is full'
* cannot-create::                `Can't create/write to file'
* commands-out-of-sync::         `Commands out of sync'
* ignoring-user::                `Ignoring user'
* cannot-find-table::            `Table 'TBL_NAME' doesn't exist'
* cannot-initialize-character-set::  `Can't initialize character set'
* not-enough-file-handles::      `'FILE' Not Found' and Similar Errors
* table-corruption::             Table-Corruption Issues

This section lists some errors that users frequently encounter when
running MySQL programs. Although the problems show up when you try to
run client programs, the solutions to many of the problems involves
changing the configuration of the MySQL server.


File: manual.info,  Node: error-access-denied,  Next: can-not-connect-to-server,  Prev: common-errors,  Up: common-errors

B.1.2.1 `Access denied'
.......................

An `Access denied' error can have many causes. Often the problem is
related to the MySQL accounts that the server allows client programs to
use when connecting.  See *Note privilege-system::, and *Note
access-denied::.


File: manual.info,  Node: can-not-connect-to-server,  Next: error-lost-connection,  Prev: error-access-denied,  Up: common-errors

B.1.2.2 `Can't connect to [local] MySQL server'
...............................................

* Menu:

* can-not-connect-to-server-on-windows::  `Connection to MySQL Server Failing on Windows'

A MySQL client on Unix can connect to the *Note `mysqld': mysqld.
server in two different ways: By using a Unix socket file to connect
through a file in the file system (default `/tmp/mysql.sock'), or by
using TCP/IP, which connects through a port number. A Unix socket file
connection is faster than TCP/IP, but can be used only when connecting
to a server on the same computer. A Unix socket file is used if you
don't specify a host name or if you specify the special host name
`localhost'.

If the MySQL server is running on Windows, you can connect via TCP/IP.
If the server is started with the `--enable-named-pipe' option, you can
also connect with named pipes if you run the client on the host where
the server is running. The name of the named pipe is `MySQL' by
default. If you don't give a host name when connecting to *Note
`mysqld': mysqld, a MySQL client first tries to connect to the named
pipe. If that doesn't work, it connects to the TCP/IP port. You can
force the use of named pipes on Windows by using `.' as the host name.

The error (2002) `Can't connect to ...' normally means that there is no
MySQL server running on the system or that you are using an incorrect
Unix socket file name or TCP/IP port number when trying to connect to
the server. You should also check that the TCP/IP port you are using
has not been blocked by a firewall or port blocking service.

The error (2003) `Can't connect to MySQL server on 'SERVER' (10061)'
indicates that the network connection has been refused. You should
check that there is a MySQL server running, that it has network
connections enabled, and that the network port you specified is the one
configured on the server.

Start by checking whether there is a process named *Note `mysqld':
mysqld. running on your server host. (Use `ps xa | grep mysqld' on Unix
or the Task Manager on Windows.) If there is no such process, you should
start the server. See *Note starting-server::.

If a *Note `mysqld': mysqld. process is running, you can check it by
trying the following commands. The port number or Unix socket file name
might be different in your setup.  `host_ip' represents the IP number
of the machine where the server is running.

     shell> mysqladmin version
     shell> mysqladmin variables
     shell> mysqladmin -h `hostname` version variables
     shell> mysqladmin -h `hostname` --port=3306 version
     shell> mysqladmin -h host_ip version
     shell> mysqladmin --protocol=SOCKET --socket=/tmp/mysql.sock version

Note the use of backticks rather than forward quotes with the
`hostname' command; these cause the output of `hostname' (that is, the
current host name) to be substituted into the *Note `mysqladmin':
mysqladmin.  command. If you have no `hostname' command or are running
on Windows, you can manually type the host name of your machine
(without backticks) following the `-h' option. You can also try `-h
127.0.0.1' to connect with TCP/IP to the local host.

Make sure that the server has not been configured to ignore network
connections or (if you are attempting to connect remotely) that it has
not been configured to listen only locally on its network interfaces.
If the server was started with `--skip-networking', it will not accept
TCP/IP connections at all. If the server was started with
`--bind-address=127.0.0.1', it will listen for TCP/IP connections only
locally on the loopback interface and will not accept remote
connections.

Check to make sure that there is no firewall blocking access to MySQL.
Your firewall may be configured on the basis of the application being
executed, or the port number used by MySQL for communication (3306 by
default). Under Linux or Unix, check your IP tables (or similar)
configuration to ensure that the port has not been blocked. Under
Windows, applications such as ZoneAlarm or the Windows XP personal
firewall may need to be configured not to block the MySQL port.

Here are some reasons the `Can't connect to local MySQL server' error
might occur:

   * *Note `mysqld': mysqld. is not running on the local host. Check
     your operating system's process list to ensure the *Note `mysqld':
     mysqld. process is present.

   * You're running a MySQL server on Windows with many TCP/IP
     connections to it. If you're experiencing that quite often your
     clients get that error, you can find a workaround here: *Note
     can-not-connect-to-server-on-windows::.

   * You are running on a system that uses MIT-pthreads. If you are
     running on a system that doesn't have native threads, *Note
     `mysqld': mysqld. uses the MIT-pthreads package.  See *Note
     which-os::. However, not all MIT-pthreads versions support Unix
     socket files. On a system without socket file support, you must
     always specify the host name explicitly when connecting to the
     server. Try using this command to check the connection to the
     server:

          shell> mysqladmin -h `hostname` version

   * Someone has removed the Unix socket file that *Note `mysqld':
     mysqld. uses (`/tmp/mysql.sock' by default). For example, you
     might have a `cron' job that removes old files from the `/tmp'
     directory. You can always run *Note `mysqladmin version':
     mysqladmin. to check whether the Unix socket file that *Note
     `mysqladmin': mysqladmin. is trying to use really exists. The fix
     in this case is to change the `cron' job to not remove
     `mysql.sock' or to place the socket file somewhere else. See *Note
     problems-with-mysql-sock::.

   * You have started the *Note `mysqld': mysqld. server with the
     `--socket=/path/to/socket' option, but forgotten to tell client
     programs the new name of the socket file. If you change the socket
     path name for the server, you must also notify the MySQL clients.
     You can do this by providing the same `--socket' option when you
     run client programs. You also need to ensure that clients have
     permission to access the `mysql.sock' file. To find out where the
     socket file is, you can do:

          shell> netstat -ln | grep mysql

     See *Note problems-with-mysql-sock::.

   * You are using Linux and one server thread has died (dumped core).
     In this case, you must kill the other *Note `mysqld': mysqld.
     threads (for example, with *Note `kill': kill. or with the *Note
     `mysql_zap': mysql-zap. script) before you can restart the MySQL
     server. See *Note crashing::.

   * The server or client program might not have the proper access
     privileges for the directory that holds the Unix socket file or
     the socket file itself. In this case, you must either change the
     access privileges for the directory or socket file so that the
     server and clients can access them, or restart *Note `mysqld':
     mysqld. with a `--socket' option that specifies a socket file name
     in a directory where the server can create it and where client
     programs can access it.

If you get the error message `Can't connect to MySQL server on
some_host', you can try the following things to find out what the
problem is:

   * Check whether the server is running on that host by executing
     `telnet some_host 3306' and pressing the Enter key a couple of
     times. (3306 is the default MySQL port number. Change the value if
     your server is listening to a different port.) If there is a MySQL
     server running and listening to the port, you should get a
     response that includes the server's version number. If you get an
     error such as `telnet: Unable to connect to remote host:
     Connection refused', then there is no server running on the given
     port.

   * If the server is running on the local host, try using *Note
     `mysqladmin -h localhost variables': mysqladmin. to connect using
     the Unix socket file. Verify the TCP/IP port number that the
     server is configured to listen to (it is the value of the `port'
     variable.)

   * If you are running under Linux and Security-Enhanced Linux
     (SELinux) is enabled, make sure you have disabled SELinux
     protection for the `mysqld' process.


File: manual.info,  Node: can-not-connect-to-server-on-windows,  Prev: can-not-connect-to-server,  Up: can-not-connect-to-server

B.1.2.3 `Connection to MySQL Server Failing on Windows'
.......................................................

When you're running a MySQL server on Windows with many TCP/IP
connections to it, and you're experiencing that quite often your
clients get a `Can't connect to MySQL server' error, the reason might
be that Windows doesn't allow for enough ephemeral (short-lived) ports
to serve those connections.

By default, Windows allows 5000 ephemeral (short-lived) TCP ports to
the user. After any port is closed it will remain in a `TIME_WAIT'
status for 120 seconds.  This status allows the connection to be reused
at a much lower cost than reinitializing a brand new connection.
However, the port will not be available again until this time expires.

With a small stack of available TCP ports (5000) and a high number of
TCP ports being open and closed over a short period of time along with
the `TIME_WAIT' status you have a good chance for running out of ports.
There are two ways to address this problem:

   * Reduce the number of TCP ports consumed quickly by investigating
     connection pooling or persistent connections where possible

   * Tune some settings in the Windows registry (see below)

* IMPORTANT: The following procedure involves modifying the Windows
registry. Before you modify the registry, make sure to back it up and
make sure that you understand how to restore the registry if a problem
occurs.  For information about how to back up, restore, and edit the
registry, view the following article in the Microsoft Knowledge Base:
`http://support.microsoft.com/kb/256986/EN-US/'.  *

  1. Start Registry Editor (`Regedt32.exe').

  2. Locate the following key in the registry:

          HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

  3. On the `Edit' menu, click `Add Value', and then add the following
     registry value:

          Value Name: MaxUserPort
          Data Type: REG_DWORD
          Value: 65534

     This sets the number of ephemeral ports available to any user. The
     valid range is between 5000 and 65534 (decimal). The default value
     is 0x1388 (5000 decimal).

  4. On the `Edit' menu, click `Add Value', and then add the following
     registry value:

          Value Name: TcpTimedWaitDelay
          Data Type: REG_DWORD
          Value: 30

     This sets the number of seconds to hold a TCP port connection in
     `TIME_WAIT' state before closing. The valid range is between 0
     (zero) and 300 (decimal). The default value is 0x78 (120 decimal).

  5. Quit Registry Editor.

  6. Reboot the machine.

Note: Undoing the above should be as simple as deleting the registry
entries you've created.


File: manual.info,  Node: error-lost-connection,  Next: old-client,  Prev: can-not-connect-to-server,  Up: common-errors

B.1.2.4 `Lost connection to MySQL server'
.........................................

There are three likely causes for this error message.

Usually it indicates network connectivity trouble and you should check
the condition of your network if this error occurs frequently. If the
error message includes `during query,' this is probably the case you
are experiencing.

Sometimes the `during query' form happens when millions of rows are
being sent as part of one or more queries. If you know that this is
happening, you should try increasing `net_read_timeout' from its
default of 30 seconds to 60 seconds or longer, sufficient for the data
transfer to complete.

More rarely, it can happen when the client is attempting the initial
connection to the server. In this case, if your `connect_timeout' value
is set to only a few seconds, you may be able to resolve the problem by
increasing it to ten seconds, perhaps more if you have a very long
distance or slow connection. You can determine whether you are
experiencing this more uncommon cause by using `SHOW GLOBAL STATUS LIKE
'Aborted_connects''.  It will increase by one for each initial
connection attempt that the server aborts. You may see `reading
authorization packet' as part of the error message; if so, that also
suggests that this is the solution that you need.

If the cause is none of those just described, you may be experiencing a
problem with *Note `BLOB': blob. values that are larger than
`max_allowed_packet', which can cause this error with some clients.
Sometime you may see `packet too large' as part of the error message,
and that confirms that you need to increase `max_allowed_packet'.


File: manual.info,  Node: old-client,  Next: password-too-long,  Prev: error-lost-connection,  Up: common-errors

B.1.2.5 `Client does not support authentication protocol'
.........................................................

MySQL 6.0 uses an authentication protocol based on a password hashing
algorithm that is incompatible with that used by older (pre-4.1)
clients. If you upgrade the server from 4.0, attempts to connect to it
with an older client may fail with the following message:

     shell> mysql
     Client does not support authentication protocol requested
     by server; consider upgrading MySQL client

To solve this problem, you should use one of the following approaches:

   * Upgrade all client programs to use a 4.1.1 or newer client library.

   * When connecting to the server with a pre-4.1 client program, use
     an account that still has a pre-4.1-style password.

   * Reset the password to pre-4.1 style for each user that needs to
     use a pre-4.1 client program. This can be done using the *Note
     `SET PASSWORD': set-password.  statement and the `OLD_PASSWORD()'
     function:

          mysql> SET PASSWORD FOR
              -> 'SOME_USER'@'SOME_HOST' = OLD_PASSWORD('NEWPWD');

     Alternatively, use *Note `UPDATE': update.  and *Note `FLUSH
     PRIVILEGES': flush.:

          mysql> UPDATE mysql.user SET Password = OLD_PASSWORD('NEWPWD')
              -> WHERE Host = 'SOME_HOST' AND User = 'SOME_USER';
          mysql> FLUSH PRIVILEGES;

     Substitute the password you want to use for `NEWPWD' in the
     preceding examples. MySQL cannot tell you what the original
     password was, so you'll need to pick a new one.

   * Tell the server to use the older password hashing algorithm:

       1. Start *Note `mysqld': mysqld. with the `--old-passwords'
          option.

       2. Assign an old-format password to each account that has had
          its password updated to the longer 4.1 format. You can
          identify these accounts with the following query:

               mysql> SELECT Host, User, Password FROM mysql.user
                   -> WHERE LENGTH(Password) > 16;

          For each account record displayed by the query, use the
          `Host' and `User' values and assign a password using the
          `OLD_PASSWORD()' function and either *Note `SET PASSWORD':
          set-password.  or *Note `UPDATE': update, as described
          earlier.

*Note*:

In older versions of PHP, the `mysql' extension does not support the
authentication protocol in MySQL 4.1.1 and higher. This is true
regardless of the PHP version being used. If you wish to use the
`mysql' extension with MySQL 4.1 or newer, you may need to follow one
of the options discussed above for configuring MySQL to work with old
clients. The `mysqli' extension (stands for "MySQL, Improved"; added in
PHP 5) is compatible with the improved password hashing employed in
MySQL 4.1 and higher, and no special configuration of MySQL need be
done to use this MySQL client library. For more information about the
`mysqli' extension, see `http://php.net/mysqli'.

It may also be possible to compile the older `mysql' extension against
the new MySQL client library. This is beyond the scope of this Manual;
consult the PHP documentation for more information. You also be able to
obtain assistance with these issues in our MySQL with PHP forum
(http://forums.mysql.com/list.php?52).

For additional background on password hashing and authentication, see
*Note password-hashing::.


File: manual.info,  Node: password-too-long,  Next: blocked-host,  Prev: old-client,  Up: common-errors

B.1.2.6 Password Fails When Entered Interactively
.................................................

MySQL client programs prompt for a password when invoked with a
`--password' or `-p' option that has no following password value:

     shell> mysql -u USER_NAME -p
     Enter password:

On some systems, you may find that your password works when specified
in an option file or on the command line, but not when you enter it
interactively at the `Enter password:' prompt. This occurs when the
library provided by the system to read passwords limits password values
to a small number of characters (typically eight). That is a problem
with the system library, not with MySQL. To work around it, change your
MySQL password to a value that is eight or fewer characters long, or
put your password in an option file.


File: manual.info,  Node: blocked-host,  Next: too-many-connections,  Prev: password-too-long,  Up: common-errors

B.1.2.7 `Host 'HOST_NAME' is blocked'
.....................................

If you get the following error, it means that *Note `mysqld': mysqld.
has received many connect requests from the host `'HOST_NAME'' that
have been interrupted in the middle:

     Host 'HOST_NAME' is blocked because of many connection errors.
     Unblock with 'mysqladmin flush-hosts'

The number of interrupted connect requests allowed is determined by the
value of the `max_connect_errors' system variable. After
`max_connect_errors' failed requests, *Note `mysqld': mysqld. assumes
that something is wrong (for example, that someone is trying to break
in), and blocks the host from further connections until you execute a
*Note `mysqladmin flush-hosts': mysqladmin. command or issue a *Note
`FLUSH HOSTS': flush.  statement. See *Note server-system-variables::.

By default, *Note `mysqld': mysqld. blocks a host after 10 connection
errors. You can adjust the value by starting the server like this:

     shell> mysqld_safe --max_connect_errors=10000 &

If you get this error message for a given host, you should first verify
that there isn't anything wrong with TCP/IP connections from that host.
If you are having network problems, it does you no good to increase the
value of the `max_connect_errors' variable.


File: manual.info,  Node: too-many-connections,  Next: out-of-memory,  Prev: blocked-host,  Up: common-errors

B.1.2.8 `Too many connections'
..............................

If you get a `Too many connections' error when you try to connect to
the *Note `mysqld': mysqld.  server, this means that all available
connections are in use by other clients.

The number of connections allowed is controlled by the
`max_connections' system variable. The default value is 151 to improve
performance when MySQL is used with the Apache Web server. (Previously,
the default was 100.) If you need to support more connections, you
should set a larger value for this variable.

MySQL Enterprise

Subscribers to the MySQL Enterprise Monitor receive advice on
dynamically configuring the `max_connections' variable -- avoiding
failed connection attempts. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Note `mysqld': mysqld. actually allows `max_connections+1' clients to
connect. The extra connection is reserved for use by accounts that have
the `SUPER' privilege. By granting the `SUPER' privilege to
administrators and not to normal users (who should not need it), an
administrator can connect to the server and use *Note `SHOW
PROCESSLIST': show-processlist. to diagnose problems even if the
maximum number of unprivileged clients are connected. See *Note
show-processlist::.

The maximum number of connections MySQL can support depends on the
quality of the thread library on a given platform. Linux or Solaris
should be able to support 500-1000 simultaneous connections, depending
on how much RAM you have and what your clients are doing. Static Linux
binaries provided by Sun Microsystems, Inc. can support up to 4000
connections.


File: manual.info,  Node: out-of-memory,  Next: gone-away,  Prev: too-many-connections,  Up: common-errors

B.1.2.9 `Out of memory'
.......................

If you issue a query using the *Note `mysql': mysql. client program and
receive an error like the following one, it means that *Note `mysql':
mysql. does not have enough memory to store the entire query result:

     mysql: Out of memory at line 42, 'malloc.c'
     mysql: needed 8136 byte (8k), memory in use: 12481367 bytes (12189k)
     ERROR 2008: MySQL client ran out of memory

To remedy the problem, first check whether your query is correct. Is it
reasonable that it should return so many rows?  If not, correct the
query and try again. Otherwise, you can invoke *Note `mysql': mysql.
with the `--quick' option. This causes it to use the *Note
`mysql_use_result()': mysql-use-result.  C API function to retrieve the
result set, which places less of a load on the client (but more on the
server).


File: manual.info,  Node: gone-away,  Next: packet-too-large,  Prev: out-of-memory,  Up: common-errors

B.1.2.10 `MySQL server has gone away'
.....................................

This section also covers the related `Lost connection to server during
query' error.

The most common reason for the `MySQL server has gone away' error is
that the server timed out and closed the connection. In this case, you
normally get one of the following error codes (which one you get is
operating system-dependent).

*Error Code*              *Description*
`CR_SERVER_GONE_ERROR'    The client couldn't send a question to the
                          server.
`CR_SERVER_LOST'          The client didn't get an error when writing to
                          the server, but it didn't get a full answer
                          (or any answer) to the question.

By default, the server closes the connection after eight hours if
nothing has happened. You can change the time limit by setting the
`wait_timeout' variable when you start *Note `mysqld': mysqld. See
*Note server-system-variables::.

If you have a script, you just have to issue the query again for the
client to do an automatic reconnection. This assumes that you have
automatic reconnection in the client enabled (which is the default for
the `mysql' command-line client).

Some other common reasons for the `MySQL server has gone away' error
are:

   * You (or the db administrator) has killed the running thread with a
     *Note `KILL': kill.  statement or a *Note `mysqladmin kill':
     mysqladmin. command.

   * You tried to run a query after closing the connection to the
     server. This indicates a logic error in the application that
     should be corrected.

   * A client application running on a different host does not have the
     necessary privileges to connect to the MySQL server from that host.

   * You got a timeout from the TCP/IP connection on the client side.
     This may happen if you have been using the commands: *Note
     `mysql_options(..., MYSQL_OPT_READ_TIMEOUT,...)': mysql-options. or
     *Note `mysql_options(..., MYSQL_OPT_WRITE_TIMEOUT,...)':
     mysql-options. In this case increasing the timeout may help solve
     the problem.

   * You have encountered a timeout on the server side and the
     automatic reconnection in the client is disabled (the `reconnect'
     flag in the `MYSQL' structure is equal to 0).

   * You are using a Windows client and the server had dropped the
     connection (probably because `wait_timeout' expired) before the
     command was issued.

     The problem on Windows is that in some cases MySQL doesn't get an
     error from the OS when writing to the TCP/IP connection to the
     server, but instead gets the error when trying to read the answer
     from the connection.

     The solution to this is to either do a *Note `mysql_ping()':
     mysql-ping. on the connection if there has been a long time since
     the last query (this is what `MyODBC' does) or set `wait_timeout'
     on the *Note `mysqld': mysqld. server so high that it in practice
     never times out.

   * You can also get these errors if you send a query to the server
     that is incorrect or too large. If *Note `mysqld': mysqld.
     receives a packet that is too large or out of order, it assumes
     that something has gone wrong with the client and closes the
     connection. If you need big queries (for example, if you are
     working with big *Note `BLOB': blob. columns), you can increase
     the query limit by setting the server's `max_allowed_packet'
     variable, which has a default value of 1MB. You may also need to
     increase the maximum packet size on the client end. More
     information on setting the packet size is given in *Note
     packet-too-large::.

     An *Note `INSERT': insert. or *Note `REPLACE': replace. statement
     that inserts a great many rows can also cause these sorts of
     errors. Either one of these statements sends a single request to
     the server irrespective of the number of rows to be inserted;
     thus, you can often avoid the error by reducing the number of rows
     sent per *Note `INSERT': insert. or *Note `REPLACE': replace.

   * You also get a lost connection if you are sending a packet 16MB or
     larger if your client is older than 4.0.8 and your server is 4.0.8
     and above, or the other way around.

   * It is also possible to see this error if host name lookups fail
     (for example, if the DNS server on which your server or network
     relies goes down). This is because MySQL is dependent on the host
     system for name resolution, but has no way of knowing whether it
     is working -- from MySQL's point of view the problem is
     indistinguishable from any other network timeout.

     You may also see the `MySQL server has gone away' error if MySQL
     is started with the `--skip-networking' option.

     Another networking issue that can cause this error occurs if the
     MySQL port (default 3306) is blocked by your firewall, thus
     preventing any connections at all to the MySQL server.

   * You can also encounter this error with applications that fork
     child processes, all of which try to use the same connection to
     the MySQL server. This can be avoided by using a separate
     connection for each child process.

   * You have encountered a bug where the server died while executing
     the query.

You can check whether the MySQL server died and restarted by executing
*Note `mysqladmin version': mysqladmin. and examining the server's
uptime. If the client connection was broken because *Note `mysqld':
mysqld. crashed and restarted, you should concentrate on finding the
reason for the crash. Start by checking whether issuing the query again
kills the server again. See *Note crashing::.

You can get more information about the lost connections by starting
*Note `mysqld': mysqld. with the `--log-warnings=2' option. This logs
some of the disconnected errors in the `hostname.err' file. See *Note
error-log::.

If you want to create a bug report regarding this problem, be sure that
you include the following information:

   * Indicate whether the MySQL server died. You can find information
     about this in the server error log. See *Note crashing::.

   * If a specific query kills *Note `mysqld': mysqld. and the tables
     involved were checked with *Note `CHECK TABLE': check-table.
     before you ran the query, can you provide a reproducible test
     case? See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * What is the value of the `wait_timeout' system variable in the
     MySQL server? (*Note `mysqladmin variables': mysqladmin. gives you
     the value of this variable.)

   * Have you tried to run *Note `mysqld': mysqld. with the general
     query log enabled to determine whether the problem query appears
     in the log? (See *Note query-log::.)

See also *Note communication-errors::, and *Note bug-reports::.


File: manual.info,  Node: packet-too-large,  Next: communication-errors,  Prev: gone-away,  Up: common-errors

B.1.2.11 `Packet too large'
...........................

A communication packet is a single SQL statement sent to the MySQL
server, a single row that is sent to the client, or a binary log event
sent from a master replication server to a slave.

The largest possible packet that can be transmitted to or from a MySQL
6.0 server or client is 1GB.

When a MySQL client or the *Note `mysqld': mysqld. server receives a
packet bigger than `max_allowed_packet' bytes, it issues a `Packet too
large' error and closes the connection. With some clients, you may also
get a `Lost connection to MySQL server during query' error if the
communication packet is too large.

Both the client and the server have their own `max_allowed_packet'
variable, so if you want to handle big packets, you must increase this
variable both in the client and in the server.

If you are using the *Note `mysql': mysql. client program, its default
`max_allowed_packet' variable is 16MB. To set a larger value, start
*Note `mysql': mysql.  like this:

     shell> mysql --max_allowed_packet=32M

That sets the packet size to 32MB.

The server's default `max_allowed_packet' value is 1MB. You can
increase this if the server needs to handle big queries (for example,
if you are working with big *Note `BLOB': blob. columns). For example,
to set the variable to 16MB, start the server like this:

     shell> mysqld --max_allowed_packet=16M

You can also use an option file to set `max_allowed_packet'. For
example, to set the size for the server to 16MB, add the following
lines in an option file:

     [mysqld]
     max_allowed_packet=16M

It is safe to increase the value of this variable because the extra
memory is allocated only when needed. For example, *Note `mysqld':
mysqld. allocates more memory only when you issue a long query or when
*Note `mysqld': mysqld. must return a large result row. The small
default value of the variable is a precaution to catch incorrect
packets between the client and server and also to ensure that you do
not run out of memory by using large packets accidentally.

You can also get strange problems with large packets if you are using
large *Note `BLOB': blob. values but have not given *Note `mysqld':
mysqld. access to enough memory to handle the query. If you suspect
this is the case, try adding `ulimit -d 256000' to the beginning of the
*Note `mysqld_safe': mysqld-safe. script and restarting *Note `mysqld':
mysqld.


File: manual.info,  Node: communication-errors,  Next: full-table,  Prev: packet-too-large,  Up: common-errors

B.1.2.12 Communication Errors and Aborted Connections
.....................................................

The server error log can be a useful source of information about
connection problems. See *Note error-log::. If you start the server
with the `--log-warnings' option, you might find messages like this in
your error log:

     010301 14:38:23  Aborted connection 854 to db: 'users' user: 'josh'

If a client successfully connects but later disconnects improperly or
is terminated, the server increments the `Aborted_clients' status
variable, and logs an `Aborted connection' message to the error log.
The cause can be any of the following:

   * The client program did not call *Note `mysql_close()':
     mysql-close. before exiting.

   * The client had been sleeping more than `wait_timeout' or
     `interactive_timeout' seconds without issuing any requests to the
     server. See *Note server-system-variables::.

   * The client program ended abruptly in the middle of a data transfer.

If a client is unable even to connect, the server increments the
`Aborted_connects' status variable. Unsuccessful connect attempts can
occur for the following reasons:

   * A client doesn't have privileges to connect to a database.

   * A client uses an incorrect password.

   * A connection packet doesn't contain the right information.

   * It takes more than `connect_timeout' seconds to get a connect
     packet. See *Note server-system-variables::.

If these kinds of things happen, it might indicate that someone is
trying to break into your server! Messages for these types of problems
are logged to the general query log if it is enabled.

MySQL Enterprise

For reasons of security and performance the advisors provided by the
MySQL Enterprise Monitor pay special attention to the
`Aborted_connects' status variable. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

Other reasons for problems with aborted clients or aborted connections:

   * Use of Ethernet protocol with Linux, both half and full duplex.
     Many Linux Ethernet drivers have this bug. You should test for
     this bug by transferring a huge file via FTP between the client
     and server machines. If a transfer goes in burst-pause-burst-pause
     mode, you are experiencing a Linux duplex syndrome. The only
     solution is switching the duplex mode for both your network card
     and hub/switch to either full duplex or to half duplex and testing
     the results to determine the best setting.

   * Some problem with the thread library that causes interrupts on
     reads.

   * Badly configured TCP/IP.

   * Faulty Ethernets, hubs, switches, cables, and so forth.  This can
     be diagnosed properly only by replacing hardware.

   * The `max_allowed_packet' variable value is too small or queries
     require more memory than you have allocated for *Note `mysqld':
     mysqld. See *Note packet-too-large::.

See also *Note gone-away::.


File: manual.info,  Node: full-table,  Next: cannot-create,  Prev: communication-errors,  Up: common-errors

B.1.2.13 `The table is full'
............................

The effective maximum table size for MySQL databases is usually
determined by operating system constraints on file sizes, not by MySQL
internal limits. The following table lists some examples of operating
system file-size limits. This is only a rough guide and is not intended
to be definitive. For the most up-to-date information, be sure to check
the documentation specific to your operating system.

*Operating System*     *File-size Limit*
Win32 w/ FAT/FAT32     2GB/4GB
Win32 w/ NTFS          2TB (possibly larger)
Linux 2.2-Intel 32-bit 2GB (LFS: 4GB)
Linux 2.4+             (using ext3 file system) 4TB
Solaris 9/10           16TB
MacOS X w/ HFS+        2TB
NetWare w/NSS file     8TB
system                 

Windows users, please note that FAT and VFAT (FAT32) are _not_
considered suitable for production use with MySQL. Use NTFS instead.

On Linux 2.2, you can get `MyISAM' tables larger than 2GB in size by
using the Large File Support (LFS) patch for the ext2 file system. Most
current Linux distributions are based on kernel 2.4 or higher and
include all the required LFS patches. On Linux 2.4, patches also exist
for ReiserFS to get support for big files (up to 2TB). With JFS and
XFS, petabyte and larger files are possible on Linux.

For a detailed overview about LFS in Linux, have a look at Andreas
Jaeger's `Large File Support in Linux' page at
`http://www.suse.de/~aj/linux_lfs.html'.

If you do encounter a full-table error, there are several reasons why
it might have occurred:

   * The `InnoDB' storage engine maintains `InnoDB' tables within a
     tablespace that can be created from several files. This allows a
     table to exceed the maximum individual file size. The tablespace
     can include raw disk partitions, which allows extremely large
     tables. The maximum tablespace size is 64TB.

     If you are using `InnoDB' tables and run out of room in the
     `InnoDB' tablespace.  In this case, the solution is to extend the
     `InnoDB' tablespace. See *Note adding-and-removing::.

   * You are using `MyISAM' tables on an operating system that supports
     files only up to 2GB in size and you have hit this limit for the
     data file or index file.

   * You are using a `MyISAM' table and the space required for the
     table exceeds what is allowed by the internal pointer size.
     `MyISAM' allows data and index files to grow up to 256TB by
     default, but this limit can be changed up to the maximum allowable
     size of 65,536TB (256^7 - 1 bytes).

     If you need a `MyISAM' table that is larger than the default limit
     and your operating system supports large files, the *Note `CREATE
     TABLE': create-table. statement supports `AVG_ROW_LENGTH' and
     `MAX_ROWS' options. See *Note create-table::. The server uses these
     options to determine how large a table to allow.

     If the pointer size is too small for an existing table, you can
     change the options with *Note `ALTER TABLE': alter-table. to
     increase a table's maximum allowable size. See *Note alter-table::.

          ALTER TABLE TBL_NAME MAX_ROWS=1000000000 AVG_ROW_LENGTH=NNN;

     You have to specify `AVG_ROW_LENGTH' only for tables with *Note
     `BLOB': blob. or *Note `TEXT': blob. columns; in this case, MySQL
     can't optimize the space required based only on the number of rows.

     To change the default size limit for `MyISAM' tables, set the
     `myisam_data_pointer_size', which sets the number of bytes used
     for internal row pointers. The value is used to set the pointer
     size for new tables if you do not specify the `MAX_ROWS' option.
     The value of `myisam_data_pointer_size' can be from 2 to 7. A
     value of 4 allows tables up to 4GB; a value of 6 allows tables up
     to 256TB.

     You can check the maximum data and index sizes by using this
     statement:

          SHOW TABLE STATUS FROM DB_NAME LIKE 'TBL_NAME';

     You also can use *Note `myisamchk -dv /path/to/table-index-file':
     myisamchk. See *Note show::, or *Note myisamchk::.

     Other ways to work around file-size limits for `MyISAM' tables are
     as follows:

        * If your large table is read only, you can use *Note
          `myisampack': myisampack. to compress it.  *Note
          `myisampack': myisampack. usually compresses a table by at
          least 50%, so you can have, in effect, much bigger tables.
          *Note `myisampack': myisampack. also can merge multiple
          tables into a single table. See *Note myisampack::.

        * MySQL includes a `MERGE' library that allows you to handle a
          collection of `MyISAM' tables that have identical structure
          as a single `MERGE' table.  See *Note merge-storage-engine::.

   * You are using the `MEMORY' (`HEAP') storage engine; in this case
     you need to increase the value of the `max_heap_table_size' system
     variable. See *Note server-system-variables::.


File: manual.info,  Node: cannot-create,  Next: commands-out-of-sync,  Prev: full-table,  Up: common-errors

B.1.2.14 `Can't create/write to file'
.....................................

If you get an error of the following type for some queries, it means
that MySQL cannot create a temporary file for the result set in the
temporary directory:

     Can't create/write to file '\\sqla3fe_0.ism'.

The preceding error is a typical message for Windows; the Unix message
is similar.

One fix is to start *Note `mysqld': mysqld. with the `--tmpdir' option
or to add the option to the `[mysqld]' section of your option file. For
example, to specify a directory of `C:\temp', use these lines:

     [mysqld]
     tmpdir=C:/temp

The `C:\temp' directory must exist and have sufficient space for the
MySQL server to write to. See *Note option-files::.

Another cause of this error can be permissions issues. Make sure that
the MySQL server can write to the `tmpdir' directory.

Check also the error code that you get with *Note `perror': perror. One
reason the server cannot write to a table is that the file system is
full:

     shell> perror 28
     OS error code  28:  No space left on device

If you get an error of the following type during startup, it indicates
that the file system and/or directory used for storing data files is
write protected. Providing the write error is to a test file, This
error is not serious and can be safely ignored.

     Can't create test file /usr/local/mysql/data/master.lower-test


File: manual.info,  Node: commands-out-of-sync,  Next: ignoring-user,  Prev: cannot-create,  Up: common-errors

B.1.2.15 `Commands out of sync'
...............................

If you get `Commands out of sync; you can't run this command now' in
your client code, you are calling client functions in the wrong order.

This can happen, for example, if you are using *Note
`mysql_use_result()': mysql-use-result. and try to execute a new query
before you have called *Note `mysql_free_result()': mysql-free-result.
It can also happen if you try to execute two queries that return data
without calling *Note `mysql_use_result()': mysql-use-result. or *Note
`mysql_store_result()': mysql-store-result. in between.


File: manual.info,  Node: ignoring-user,  Next: cannot-find-table,  Prev: commands-out-of-sync,  Up: common-errors

B.1.2.16 `Ignoring user'
........................

If you get the following error, it means that when *Note `mysqld':
mysqld. was started or when it reloaded the grant tables, it found an
account in the `user' table that had an invalid password.

`Found wrong password for user 'SOME_USER'@'SOME_HOST'; ignoring user'

As a result, the account is simply ignored by the permission system.

The following list indicates possible causes of and fixes for this
problem:

   * You may be running a new version of *Note `mysqld': mysqld. with
     an old `user' table. You can check this by executing *Note
     `mysqlshow mysql user': mysqlshow. to see whether the `Password'
     column is shorter than 16 characters. If so, you can correct this
     condition by running the `scripts/add_long_password' script.

   * The account has an old password (eight characters long).  Update
     the account in the `user' table to have a new password.

   * You have specified a password in the `user' table without using the
     `PASSWORD()' function. Use *Note `mysql': mysql. to update the
     account in the `user' table with a new password, making sure to
     use the `PASSWORD()' function:

          mysql> UPDATE user SET Password=PASSWORD('NEWPWD')
              -> WHERE User='SOME_USER' AND Host='SOME_HOST';


File: manual.info,  Node: cannot-find-table,  Next: cannot-initialize-character-set,  Prev: ignoring-user,  Up: common-errors

B.1.2.17 `Table 'TBL_NAME' doesn't exist'
.........................................

If you get either of the following errors, it usually means that no
table exists in the default database with the given name:

     Table 'TBL_NAME' doesn't exist
     Can't find file: 'TBL_NAME' (errno: 2)

In some cases, it may be that the table does exist but that you are
referring to it incorrectly:

   * Because MySQL uses directories and files to store databases and
     tables, database and table names are case sensitive if they are
     located on a file system that has case-sensitive file names.

   * Even for file systems that are not case sensitive, such as on
     Windows, all references to a given table within a query must use
     the same lettercase.

You can check which tables are in the default database with *Note `SHOW
TABLES': show-tables. See *Note show::.


File: manual.info,  Node: cannot-initialize-character-set,  Next: not-enough-file-handles,  Prev: cannot-find-table,  Up: common-errors

B.1.2.18 `Can't initialize character set'
.........................................

You might see an error like this if you have character set problems:

     MySQL Connection Failed: Can't initialize character set CHARSET_NAME

This error can have any of the following causes:

   * The character set is a multi-byte character set and you have no
     support for the character set in the client. In this case, you
     need to recompile the client by running `configure' with the
     `--with-charset=CHARSET_NAME' or `
     role="configure"--with-extra-charsets=CHARSET_NAME' option. See
     *Note configure-options::.

     All standard MySQL binaries are compiled with
     `--with-extra-charsets=complex', which enables support for all
     multi-byte character sets.  See *Note charset-configuration::.

   * The character set is a simple character set that is not compiled
     into *Note `mysqld': mysqld, and the character set definition
     files are not in the place where the client expects to find them.

     In this case, you need to use one of the following methods to
     solve the problem:

        * Recompile the client with support for the character set. See
          *Note configure-options::.

        * Specify to the client the directory where the character set
          definition files are located. For many clients, you can do
          this with the `--character-sets-dir' option.

        * Copy the character definition files to the path where the
          client expects them to be.


File: manual.info,  Node: not-enough-file-handles,  Next: table-corruption,  Prev: cannot-initialize-character-set,  Up: common-errors

B.1.2.19 `'FILE' Not Found' and Similar Errors
..............................................

If you get `ERROR '...' not found (errno: 23)', `Can't open file: ...
(errno: 24)', or any other error with `errno 23' or `errno 24' from
MySQL, it means that you haven't allocated enough file descriptors for
the MySQL server. You can use the *Note `perror': perror.  utility to
get a description of what the error number means:

     shell> perror 23
     OS error code  23:  File table overflow
     shell> perror 24
     OS error code  24:  Too many open files
     shell> perror 11
     OS error code  11:  Resource temporarily unavailable

The problem here is that *Note `mysqld': mysqld. is trying to keep open
too many files simultaneously. You can either tell *Note `mysqld':
mysqld. not to open so many files at once or increase the number of
file descriptors available to *Note `mysqld': mysqld.

To tell *Note `mysqld': mysqld. to keep open fewer files at a time, you
can make the table cache smaller by reducing the value of the
`table_open_cache' system variable (the default value is 64). Reducing
the value of `max_connections' also reduces the number of open files
(the default value is 100).

To change the number of file descriptors available to *Note `mysqld':
mysqld, you can use the `--open-files-limit' option to *Note
`mysqld_safe': mysqld-safe. or set the `open_files_limit' system
variable. See *Note server-system-variables::. The easiest way to set
these values is to add an option to your option file. See *Note
option-files::. If you have an old version of *Note `mysqld': mysqld.
that doesn't support setting the open files limit, you can edit the
*Note `mysqld_safe': mysqld-safe. script. There is a commented-out line
`ulimit -n 256' in the script. You can remove the ``#'' character to
uncomment this line, and change the number `256' to set the number of
file descriptors to be made available to *Note `mysqld': mysqld.

`--open-files-limit' and `ulimit' can increase the number of file
descriptors, but only up to the limit imposed by the operating system.
There is also a `hard' limit that can be overridden only if you start
*Note `mysqld_safe': mysqld-safe. or *Note `mysqld': mysqld. as `root'
(just remember that you also need to start the server with the `--user'
option in this case so that it does not continue to run as `root' after
it starts up). If you need to increase the operating system limit on
the number of file descriptors available to each process, consult the
documentation for your system.

*Note*:

If you run the `tcsh' shell, `ulimit' does not work!  `tcsh' also
reports incorrect values when you ask for the current limits. In this
case, you should start *Note `mysqld_safe': mysqld-safe. using `sh'.


File: manual.info,  Node: table-corruption,  Prev: not-enough-file-handles,  Up: common-errors

B.1.2.20 Table-Corruption Issues
................................

If you have started *Note `mysqld': mysqld. with `--myisam-recover',
MySQL automatically checks and tries to repair `MyISAM' tables if they
are marked as 'not closed properly' or 'crashed'. If this happens,
MySQL writes an entry in the `hostname.err' file `'Warning: Checking
table ...'' which is followed by `Warning: Repairing table' if the
table needs to be repaired. If you get a lot of these errors, without
*Note `mysqld': mysqld. having died unexpectedly just before, then
something is wrong and needs to be investigated further.

As of MySQL 6.0.4, when the server detects `MyISAM' table corruption,
it writes additional information to the error log, such as the name and
line number of the source file, and the list of threads accessing the
table. Example: `Got an error from thread_id=1, mi_dynrec.c:368 '. This
is useful information to include in bug reports.

See also *Note server-options::, and *Note reproducible-test-case::.


File: manual.info,  Node: installation-issues,  Next: administration-issues,  Prev: common-errors,  Up: problems

B.1.3 Installation-Related Issues
---------------------------------

* Menu:

* link-errors::                  Problems Linking to the MySQL Client Library
* file-permissions::             Problems with File Permissions


File: manual.info,  Node: link-errors,  Next: file-permissions,  Prev: installation-issues,  Up: installation-issues

B.1.3.1 Problems Linking to the MySQL Client Library
....................................................

When you are linking an application program to use the MySQL client
library, you might get undefined reference errors for symbols that
start with `mysql_', such as those shown here:

     /tmp/ccFKsdPa.o: In function `main':
     /tmp/ccFKsdPa.o(.text+0xb): undefined reference to `mysql_init'
     /tmp/ccFKsdPa.o(.text+0x31): undefined reference to `mysql_real_connect'
     /tmp/ccFKsdPa.o(.text+0x57): undefined reference to `mysql_real_connect'
     /tmp/ccFKsdPa.o(.text+0x69): undefined reference to `mysql_error'
     /tmp/ccFKsdPa.o(.text+0x9a): undefined reference to `mysql_close'

You should be able to solve this problem by adding `-Ldir_path
-lmysqlclient' at the end of your link command, where `dir_path'
represents the path name of the directory where the client library is
located. To determine the correct directory, try this command:

     shell> mysql_config --libs

The output from *Note `mysql_config': mysql-config. might indicate
other libraries that should be specified on the link command as well.

If you get `undefined reference' errors for the `uncompress' or
`compress' function, add `-lz' to the end of your link command and try
again.

If you get `undefined reference' errors for a function that should
exist on your system, such as `connect', check the manual page for the
function in question to determine which libraries you should add to the
link command.

You might get `undefined reference' errors such as the following for
functions that don't exist on your system:

     mf_format.o(.text+0x201): undefined reference to `__lxstat'

This usually means that your MySQL client library was compiled on a
system that is not 100% compatible with yours. In this case, you should
download the latest MySQL source distribution and compile MySQL
yourself. See *Note installing-source::.

You might get undefined reference errors at runtime when you try to
execute a MySQL program. If these errors specify symbols that start
with `mysql_' or indicate that the `mysqlclient' library can't be
found, it means that your system can't find the shared
`libmysqlclient.so' library. The fix for this is to tell your system to
search for shared libraries where the library is located. Use whichever
of the following methods is appropriate for your system:

   * Add the path to the directory where `libmysqlclient.so' is located
     to the `LD_LIBRARY_PATH' environment variable.

   * Add the path to the directory where `libmysqlclient.so' is located
     to the `LD_LIBRARY' environment variable.

   * Copy `libmysqlclient.so' to some directory that is searched by
     your system, such as `/lib', and update the shared library
     information by executing `ldconfig'.

Another way to solve this problem is by linking your program statically
with the `-static' option, or by removing the dynamic MySQL libraries
before linking your code.  Before trying the second method, you should
be sure that no other programs are using the dynamic libraries.


File: manual.info,  Node: file-permissions,  Prev: link-errors,  Up: installation-issues

B.1.3.2 Problems with File Permissions
......................................

If you have problems with file permissions, the `UMASK' environment
variable might be set incorrectly when *Note `mysqld': mysqld. starts.
For example, MySQL might issue the following error message when you
create a table:

     ERROR: Can't find file: 'path/with/filename.frm' (Errcode: 13)

The default `UMASK' value is `0660'. You can change this behavior by
starting *Note `mysqld_safe': mysqld-safe. as follows:

     shell> UMASK=384  # = 600 in octal
     shell> export UMASK
     shell> mysqld_safe &

By default, MySQL creates database directories with an access
permission value of `0700'. You can modify this behavior by setting the
`UMASK_DIR' variable. If you set its value, new directories are created
with the combined `UMASK' and `UMASK_DIR' values. For example, if you
want to give group access to all new directories, you can do this:

     shell> UMASK_DIR=504  # = 770 in octal
     shell> export UMASK_DIR
     shell> mysqld_safe &

MySQL assumes that the value for `UMASK' or `UMASK_DIR' is in octal if
it starts with a zero.

See *Note environment-variables::.


File: manual.info,  Node: administration-issues,  Next: query-issues,  Prev: installation-issues,  Up: problems

B.1.4 Administration-Related Issues
-----------------------------------

* Menu:

* resetting-permissions::        How to Reset the Root Password
* crashing::                     What to Do If MySQL Keeps Crashing
* full-disk::                    How MySQL Handles a Full Disk
* temporary-files::              Where MySQL Stores Temporary Files
* problems-with-mysql-sock::     How to Protect or Change the MySQL Unix Socket File
* timezone-problems::            Time Zone Problems


File: manual.info,  Node: resetting-permissions,  Next: crashing,  Prev: administration-issues,  Up: administration-issues

B.1.4.1 How to Reset the Root Password
......................................

* Menu:

* resetting-permissions-windows::  Resetting the Root Password on Windows Systems
* resetting-permissions-unix::   Resetting the Root Password on Unix Systems

If you have never set a `root' password for MySQL, the server does not
require a password at all for connecting as `root'. However, it is
recommended to set a password for each account. See *Note
security-guidelines::.

If you set a `root' password previously, but have forgotten what it
was, you can set a new password. The next two sections show procedures
for Windows and Unix systems, respectively.


File: manual.info,  Node: resetting-permissions-windows,  Next: resetting-permissions-unix,  Prev: resetting-permissions,  Up: resetting-permissions

B.1.4.2 Resetting the Root Password on Windows Systems
......................................................

Use the following procedure for resetting the password for any MySQL
`root' accounts on Windows:

  1. Log on to your system as Administrator.

  2. Stop the MySQL server if it is running. For a server that is
     running as a Windows service, go to the Services manager:

          Start Menu -> Control Panel -> Administrative Tools -> Services

     Then find the MySQL service in the list, and stop it.

     If your server is not running as a service, you may need to use
     the Task Manager to force it to stop.

  3. Create a text file and place the following statements in it.
     Replace the password with the password that you want to use.

          UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root';
          FLUSH PRIVILEGES;

     The *Note `UPDATE': update. and *Note `FLUSH': flush. statements
     each must be written on a single line. The *Note `UPDATE': update.
     statement resets the password for all existing `root' accounts,
     and the *Note `FLUSH': flush.  statement tells the server to
     reload the grant tables into memory.

  4. Save the file. For this example, the file will be named
     `C:\mysql-init.txt'.

  5. Open a console window to get to the command prompt:

          Start Menu -> Run -> cmd

  6. Start the MySQL server with the special `--init-file' option:

          C:\> C:\mysql\bin\mysqld --init-file=C:\mysql-init.txt

     If you installed MySQL to a location other than `C:\mysql', adjust
     the command accordingly.

     The server executes the contents of the file named by the
     `--init-file' option at startup, changing each `root' account
     password.

     You can also add the `--console' option to the command if you want
     server output to appear in the console window rather than in a log
     file.

     If you installed MySQL using the MySQL Installation Wizard, you
     may need to specify a `--defaults-file' option:

          C:\> "C:\Program Files\MySQL\MySQL Server 6.0\bin\mysqld.exe"
                   --defaults-file="C:\Program Files\MySQL\MySQL Server 6.0\my.ini"
                   --init-file=C:\mysql-init.txt

     The appropriate `--defaults-file' setting can be found using the
     Services Manager:

          Start Menu -> Control Panel -> Administrative Tools -> Services

     Find the MySQL service in the list, right-click on it, and choose
     the `Properties' option. The `Path to executable' field contains
     the `--defaults-file' setting.

  7. After the server has started successfully, delete
     `C:\mysql-init.txt'.

  8. Stop the MySQL server, then restart it in normal mode again. If
     you run the server as a service, start it from the Windows
     Services window. If you start the server manually, use whatever
     command you normally use.

You should now be able to connect to MySQL as `root' using the new
password.


File: manual.info,  Node: resetting-permissions-unix,  Prev: resetting-permissions-windows,  Up: resetting-permissions

B.1.4.3 Resetting the Root Password on Unix Systems
...................................................

MySQL Enterprise

For expert advice on security-related issues, subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

Use the following procedure for resetting the password for any MySQL
`root' accounts on Unix. The instructions assume that you will start
the server so that it runs using the Unix login account that you
normally use for running the server. For example, if you run the server
using the `mysql' login account, you should log in as `mysql' before
using the instructions. (Alternatively, you can log in as `root', but
in this case you _must_ start start *Note `mysqld': mysqld. with the
`--user=mysql' option. If you start the server as `root' without using
`--user=mysql', the server may create `root'-owned files in the data
directory, such as log files, and these may cause permission-related
problems for future server startups. If that happens, you will need to
either change the ownership of the files to `mysql' or remove them.)

  1. Log on to your system as the Unix `mysql' user that the *Note
     `mysqld': mysqld. server runs as.

  2. Locate the `.pid' file that contains the server's process ID. The
     exact location and name of this file depend on your distribution,
     host name, and configuration. Common locations are
     `/var/lib/mysql/', `/var/run/mysqld/', and
     `/usr/local/mysql/data/'. Generally, the file name has an
     extension of `.pid' and begins with either `mysqld' or your
     system's host name.

     You can stop the MySQL server by sending a normal `kill' (not
     `kill -9') to the *Note `mysqld': mysqld. process, using the path
     name of the `.pid' file in the following command:

          shell> kill `cat /mysql-data-directory/host_name.pid`

     Note the use of backticks rather than forward quotes with the
     `cat' command; these cause the output of `cat' to be substituted
     into the `kill' command.

  3. Create a text file and place the following statements in it.
     Replace the password with the password that you want to use.

          UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root';
          FLUSH PRIVILEGES;

     The *Note `UPDATE': update. and *Note `FLUSH': flush. statements
     each must be written on a single line. The *Note `UPDATE': update.
     statement resets the password for all existing `root' accounts,
     and the *Note `FLUSH': flush.  statement tells the server to
     reload the grant tables into memory.

  4. Save the file. For this example, the file will be named
     `/home/me/mysql-init'. The file contains the password, so it
     should not be saved where it can be read by other users.

  5. Start the MySQL server with the special `--init-file' option:

          shell> mysqld_safe --init-file=/home/me/mysql-init &

     The server executes the contents of the file named by the
     `--init-file' option at startup, changing each `root' account
     password.

  6. After the server has started successfully, delete
     `/home/me/mysql-init'.

You should now be able to connect to MySQL as `root' using the new
password.

Alternatively, on any platform, you can set the new password using the
*Note `mysql': mysql. client (but this approach is less secure):

  1. Stop *Note `mysqld': mysqld. and restart it with the
     `--skip-grant-tables' option.

  2. Connect to the *Note `mysqld': mysqld. server with this command:

          shell> mysql

  3. Issue the following statements in the *Note `mysql': mysql.
     client. Replace the password with the password that you want to
     use.

          mysql> UPDATE mysql.user SET Password=PASSWORD('MyNewPass')
              ->                   WHERE User='root';
          mysql> FLUSH PRIVILEGES;

You should now be able to connect to MySQL as `root' using the new
password.


File: manual.info,  Node: crashing,  Next: full-disk,  Prev: resetting-permissions,  Up: administration-issues

B.1.4.4 What to Do If MySQL Keeps Crashing
..........................................

Each MySQL version is tested on many platforms before it is released.
This doesn't mean that there are no bugs in MySQL, but if there are
bugs, they should be very few and can be hard to find. If you have a
problem, it always helps if you try to find out exactly what crashes
your system, because you have a much better chance of getting the
problem fixed quickly.

First, you should try to find out whether the problem is that the *Note
`mysqld': mysqld. server dies or whether your problem has to do with
your client. You can check how long your *Note `mysqld': mysqld. server
has been up by executing *Note `mysqladmin version': mysqladmin. If
*Note `mysqld': mysqld. has died and restarted, you may find the reason
by looking in the server's error log. See *Note error-log::.

On some systems, you can find in the error log a stack trace of where
*Note `mysqld': mysqld. died that you can resolve with the
`resolve_stack_dump' program. See MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting). Note that the
variable values written in the error log may not always be 100% correct.

Many server crashes are caused by corrupted data files or index files.
MySQL updates the files on disk with the `write()' system call after
every SQL statement and before the client is notified about the result.
(This is not true if you are running with `--delay-key-write', in which
case data files are written but not index files.) This means that data
file contents are safe even if *Note `mysqld': mysqld. crashes, because
the operating system ensures that the unflushed data is written to
disk. You can force MySQL to flush everything to disk after every SQL
statement by starting *Note `mysqld': mysqld. with the `--flush' option.

The preceding means that normally you should not get corrupted tables
unless one of the following happens:

   * The MySQL server or the server host was killed in the middle of an
     update.

   * You have found a bug in *Note `mysqld': mysqld. that caused it to
     die in the middle of an update.

   * Some external program is manipulating data files or index files at
     the same time as *Note `mysqld': mysqld.  without locking the
     table properly.

   * You are running many *Note `mysqld': mysqld. servers using the
     same data directory on a system that doesn't support good file
     system locks (normally handled by the `lockd' lock manager), or
     you are running multiple servers with external locking disabled.

   * You have a crashed data file or index file that contains very
     corrupt data that confused *Note `mysqld': mysqld.

   * You have found a bug in the data storage code. This isn't likely,
     but it is at least possible. In this case, you can try to change
     the storage engine to another engine by using *Note `ALTER TABLE':
     alter-table. on a repaired copy of the table.

Because it is very difficult to know why something is crashing, first
try to check whether things that work for others crash for you. Please
try the following things:

   * Stop the *Note `mysqld': mysqld. server with *Note `mysqladmin
     shutdown': mysqladmin, run *Note `myisamchk --silent --force
     */*.MYI': myisamchk. from the data directory to check all `MyISAM'
     tables, and restart *Note `mysqld': mysqld. This ensures that you
     are running from a clean state. See *Note server-administration::.

   * Start *Note `mysqld': mysqld. with the general query log enabled
     (see *Note query-log::). Then try to determine from the
     information written to the log whether some specific query kills
     the server. About 95% of all bugs are related to a particular
     query. Normally, this is one of the last queries in the log file
     just before the server restarts. See *Note query-log::. If you can
     repeatedly kill MySQL with a specific query, even when you have
     checked all tables just before issuing it, then you have been able
     to locate the bug and should submit a bug report for it. See *Note
     bug-reports::.

   * Try to make a test case that we can use to repeat the problem. See
     MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * Try running the tests in the `mysql-test' directory and the MySQL
     benchmarks. See *Note mysql-test-suite::. They should test MySQL
     rather well. You can also add code to the benchmarks that
     simulates your application. The benchmarks can be found in the
     `sql-bench' directory in a source distribution or, for a binary
     distribution, in the `sql-bench' directory under your MySQL
     installation directory.

   * Try the `fork_big.pl' script. (It is located in the `tests'
     directory of source distributions.)

   * If you configure MySQL for debugging, it is much easier to gather
     information about possible errors if something goes wrong.
     Configuring MySQL for debugging causes a safe memory allocator to
     be included that can find some errors.  It also provides a lot of
     output about what is happening.  Reconfigure MySQL with the
     `--with-debug' or `--with-debug=full' option to `configure' and
     then recompile. See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * Make sure that you have applied the latest patches for your
     operating system.

   * Use the `--skip-external-locking' option to *Note `mysqld':
     mysqld. On some systems, the `lockd' lock manager does not work
     properly; the `--skip-external-locking' option tells *Note
     `mysqld': mysqld. not to use external locking. (This means that
     you cannot run two *Note `mysqld': mysqld. servers on the same data
     directory and that you must be careful if you use *Note
     `myisamchk': myisamchk. Nevertheless, it may be instructive to try
     the option as a test.)

   * Have you tried *Note `mysqladmin -u root processlist': mysqladmin.
     when *Note `mysqld': mysqld.  appears to be running but not
     responding? Sometimes *Note `mysqld': mysqld. is not comatose even
     though you might think so. The problem may be that all connections
     are in use, or there may be some internal lock problem.  *Note
     `mysqladmin -u root processlist': mysqladmin. usually is able to
     make a connection even in these cases, and can provide useful
     information about the current number of connections and their
     status.

   * Run the command *Note `mysqladmin -i 5 status': mysqladmin.  or
     *Note `mysqladmin -i 5 -r status': mysqladmin. in a separate
     window to produce statistics while you run your other queries.

   * Try the following:

       1. Start *Note `mysqld': mysqld. from `gdb' (or another
          debugger). See MySQL Internals: Porting
          (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

       2. Run your test scripts.

       3. Print the backtrace and the local variables at the three
          lowest levels. In `gdb', you can do this with the following
          commands when *Note `mysqld': mysqld. has crashed inside
          `gdb':

               backtrace
               info local
               up
               info local
               up
               info local

          With `gdb', you can also examine which threads exist with
          `info threads' and switch to a specific thread with `thread
          N', where N is the thread ID.

   * Try to simulate your application with a Perl script to force MySQL
     to crash or misbehave.

   * Send a normal bug report. See *Note bug-reports::. Be even more
     detailed than usual. Because MySQL works for many people, it may
     be that the crash results from something that exists only on your
     computer (for example, an error that is related to your particular
     system libraries).

   * If you have a problem with tables containing dynamic-length rows
     and you are using only *Note `VARCHAR': char. columns (not *Note
     `BLOB': blob. or *Note `TEXT': blob. columns), you can try to
     change all *Note `VARCHAR': char. to *Note `CHAR': char. with
     *Note `ALTER TABLE': alter-table. This forces MySQL to use
     fixed-size rows. Fixed-size rows take a little extra space, but
     are much more tolerant to corruption.

     The current dynamic row code has been in use for several years
     with very few problems, but dynamic-length rows are by nature more
     prone to errors, so it may be a good idea to try this strategy to
     see whether it helps.

   * Do not rule out your server hardware when diagnosing problems.
     Defective hardware can be the cause of data corruption. Particular
     attention should be paid to your memory and disk subsystems when
     troubleshooting hardware.


File: manual.info,  Node: full-disk,  Next: temporary-files,  Prev: crashing,  Up: administration-issues

B.1.4.5 How MySQL Handles a Full Disk
.....................................

This section describes how MySQL responds to disk-full errors (such as
`no space left on device'), and to quota-exceeded errors (such as
`write failed' or `user block limit reached').

This section is relevant for writes to `MyISAM' tables. It also applies
for writes to binary log files and binary log index file, except that
references to `row' and `record' should be understood to mean `event.'

When a disk-full condition occurs, MySQL does the following:

   * It checks once every minute to see whether there is enough space
     to write the current row. If there is enough space, it continues
     as if nothing had happened.

   * Every 10 minutes it writes an entry to the log file, warning about
     the disk-full condition.

To alleviate the problem, you can take the following actions:

   * To continue, you only have to free enough disk space to insert all
     records.

   * To abort the thread, you must use *Note `mysqladmin kill':
     mysqladmin. The thread is aborted the next time it checks the disk
     (in one minute).

   * Other threads might be waiting for the table that caused the
     disk-full condition. If you have several `locked' threads, killing
     the one thread that is waiting on the disk-full condition allows
     the other threads to continue.

Exceptions to the preceding behavior are when you use *Note `REPAIR
TABLE': repair-table. or *Note `OPTIMIZE TABLE': optimize-table. or
when the indexes are created in a batch after *Note `LOAD DATA INFILE':
load-data. or after an *Note `ALTER TABLE': alter-table. statement. All
of these statements may create large temporary files that, if left to
themselves, would cause big problems for the rest of the system. If the
disk becomes full while MySQL is doing any of these operations, it
removes the big temporary files and mark the table as crashed. The
exception is that for *Note `ALTER TABLE': alter-table, the old table
is left unchanged.

MySQL Enterprise

For early notification of possible problems with your MySQL
configuration subscribe to the MySQL Enterprise Monitor. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: temporary-files,  Next: problems-with-mysql-sock,  Prev: full-disk,  Up: administration-issues

B.1.4.6 Where MySQL Stores Temporary Files
..........................................

MySQL uses the value of the `TMPDIR' environment variable as the path
name of the directory in which to store temporary files. If you don't
have `TMPDIR' set, MySQL uses the system default, which is normally
`/tmp', `/var/tmp', or `/usr/tmp'. If the file system containing your
temporary file directory is too small, you can use the `--tmpdir'
option to *Note `mysqld': mysqld. to specify a directory in a file
system where you have enough space.

In MySQL 6.0, the `--tmpdir' option can be set to a list of several
paths that are used in round-robin fashion.  Paths should be separated
by colon characters (``:'') on Unix and semicolon characters (``;'') on
Windows, NetWare, and OS/2.

*Note*:

To spread the load effectively, these paths should be located on
different _physical_ disks, not different partitions of the same disk.

If the MySQL server is acting as a replication slave, you should not
set `--tmpdir' to point to a directory on a memory-based file system or
to a directory that is cleared when the server host restarts. A
replication slave needs some of its temporary files to survive a
machine restart so that it can replicate temporary tables or *Note
`LOAD DATA INFILE': load-data. operations. If files in the temporary
file directory are lost when the server restarts, replication fails.

MySQL creates all temporary files as hidden files. This ensures that
the temporary files are removed if *Note `mysqld': mysqld. is
terminated. The disadvantage of using hidden files is that you do not
see a big temporary file that fills up the file system in which the
temporary file directory is located.

MySQL Enterprise

Advisors provided by the MySQL Enterprise Monitor automatically detect
excessive temporary table storage to disk. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

When sorting (`ORDER BY' or `GROUP BY'), MySQL normally uses one or two
temporary files.  The maximum disk space required is determined by the
following expression:

     (length of what is sorted + sizeof(row pointer))
     * number of matched rows
     * 2

The row pointer size is usually four bytes, but may grow in the future
for really big tables.

For some *Note `SELECT': select. queries, MySQL also creates temporary
SQL tables. These are not hidden and have names of the form `SQL_*'.

*Note `ALTER TABLE': alter-table. creates a temporary table in the same
directory as the original table.


File: manual.info,  Node: problems-with-mysql-sock,  Next: timezone-problems,  Prev: temporary-files,  Up: administration-issues

B.1.4.7 How to Protect or Change the MySQL Unix Socket File
...........................................................

The default location for the Unix socket file that the server uses for
communication with local clients is `/tmp/mysql.sock'. (For some
distribution formats, the directory might be different, such as
`/var/lib/mysql' for RPMs.)

On some versions of Unix, anyone can delete files in the `/tmp'
directory or other similar directories used for temporary files. If the
socket file is located in such a directory on your system, this might
cause problems.

On most versions of Unix, you can protect your `/tmp' directory so that
files can be deleted only by their owners or the superuser (`root'). To
do this, set the `sticky' bit on the `/tmp' directory by logging in as
`root' and using the following command:

     shell> chmod +t /tmp

You can check whether the `sticky' bit is set by executing `ls -ld
/tmp'. If the last permission character is `t', the bit is set.

Another approach is to change the place where the server creates the
Unix socket file. If you do this, you should also let client programs
know the new location of the file. You can specify the file location in
several ways:

   * Specify the path in a global or local option file. For example,
     put the following lines in `/etc/my.cnf':

          [mysqld]
          socket=/path/to/socket

          [client]
          socket=/path/to/socket

     See *Note option-files::.

   * Specify a `--socket' option on the command line to *Note
     `mysqld_safe': mysqld-safe. and when you run client programs.

   * Set the `MYSQL_UNIX_PORT' environment variable to the path of the
     Unix socket file.

   * Recompile MySQL from source to use a different default Unix socket
     file location. Define the path to the file with the
     `--with-unix-socket-path' option when you run `configure'. See
     *Note configure-options::.

You can test whether the new socket location works by attempting to
connect to the server with this command:

     shell> mysqladmin --socket=/path/to/socket version


File: manual.info,  Node: timezone-problems,  Prev: problems-with-mysql-sock,  Up: administration-issues

B.1.4.8 Time Zone Problems
..........................

If you have a problem with `SELECT NOW()' returning values in UTC and
not your local time, you have to tell the server your current time
zone. The same applies if `UNIX_TIMESTAMP()' returns the wrong value.
This should be done for the environment in which the server runs; for
example, in *Note `mysqld_safe': mysqld-safe. or *Note `mysql.server':
mysql-server. See *Note environment-variables::.

You can set the time zone for the server with the
`--timezone=TIMEZONE_NAME' option to *Note `mysqld_safe': mysqld-safe.
You can also set it by setting the `TZ' environment variable before you
start *Note `mysqld': mysqld.

The allowable values for `--timezone' or `TZ' are system-dependent.
Consult your operating system documentation to see what values are
acceptable.


File: manual.info,  Node: query-issues,  Next: optimizer-issues,  Prev: administration-issues,  Up: problems

B.1.5 Query-Related Issues
--------------------------

* Menu:

* case-sensitivity::             Case Sensitivity in String Searches
* using-date::                   Problems Using `DATE' Columns
* problems-with-null::           Problems with `NULL' Values
* problems-with-alias::          Problems with Column Aliases
* non-transactional-tables::     Rollback Failure for Non-Transactional Tables
* deleting-from-related-tables::  Deleting Rows from Related Tables
* no-matching-rows::             Solving Problems with No Matching Rows
* problems-with-float::          Problems with Floating-Point Comparisons


File: manual.info,  Node: case-sensitivity,  Next: using-date,  Prev: query-issues,  Up: query-issues

B.1.5.1 Case Sensitivity in String Searches
...........................................

For non-binary strings (*Note `CHAR': char, *Note `VARCHAR': char,
*Note `TEXT': blob.), string searches use the collation of the
comparison operands. For binary strings (*Note `BINARY':
binary-varbinary, *Note `VARBINARY': binary-varbinary, *Note `BLOB':
blob.), comparisons use the numeric values of the bytes in the
operands; this means that for alphabetic characters, comparisons will
be case sensitive.

A comparison between a non-binary string and binary string is treated
as a comparison of binary strings.

Simple comparison operations (`>=, >, =, <, <=', sorting, and grouping)
are based on each character's `sort value.' Characters with the same
sort value are treated as the same character. For example, if ``e'' and
``e''' have the same sort value in a given collation, they compare as
equal.

The default character set and collation are `latin1' and
`latin1_swedish_ci', so non-binary string comparisons are case
insensitive by default. This means that if you search with `COL_NAME
LIKE 'a%'', you get all column values that start with `A' or `a'. To
make this search case sensitive, make sure that one of the operands has
a case sensitive or binary collation. For example, if you are comparing
a column and a string that both have the `latin1' character set, you
can use the `COLLATE' operator to cause either operand to have the
`latin1_general_cs' or `latin1_bin' collation:

     COL_NAME COLLATE latin1_general_cs LIKE 'a%'
     COL_NAME LIKE 'a%' COLLATE latin1_general_cs
     COL_NAME COLLATE latin1_bin LIKE 'a%'
     COL_NAME LIKE 'a%' COLLATE latin1_bin

If you want a column always to be treated in case-sensitive fashion,
declare it with a case sensitive or binary collation.  See *Note
create-table::.

To cause a case-sensitive comparison of non-binary strings to be case
insensitive, use `COLLATE' to name a case-insensitive collation. The
strings in the following example normally are case sensitive, but
`COLLATE' changes the comparison to be case insensitive:

     mysql> SET @s1 = 'MySQL' COLLATE latin1_bin,
         ->     @s2 = 'mysql' COLLATE latin1_bin;
     mysql> SELECT @s1 = @s2;
     +-----------+
     | @s1 = @s2 |
     +-----------+
     |         0 |
     +-----------+
     mysql> SELECT @s1 COLLATE latin1_swedish_ci = @s2;
     +-------------------------------------+
     | @s1 COLLATE latin1_swedish_ci = @s2 |
     +-------------------------------------+
     |                                   1 |
     +-------------------------------------+

A binary string is case sensitive in comparisons. To compare the string
as case insensitive, convert it to a non-binary string and use
`COLLATE' to name a case-insensitive collation:

     mysql> SET @s = BINARY 'MySQL';
     mysql> SELECT @s = 'mysql';
     +--------------+
     | @s = 'mysql' |
     +--------------+
     |            0 |
     +--------------+
     mysql> SELECT CONVERT(@s USING latin1) COLLATE latin1_swedish_ci = 'mysql';
     +--------------------------------------------------------------+
     | CONVERT(@s USING latin1) COLLATE latin1_swedish_ci = 'mysql' |
     +--------------------------------------------------------------+
     |                                                            1 |
     +--------------------------------------------------------------+

To determine whether a value will compare as a non-binary or binary
string, use the `COLLATION()' function. This example shows that
`VERSION()' returns a string that has a case-insensitive collation, so
comparisons are case insensitive:

     mysql> SELECT COLLATION(VERSION());
     +----------------------+
     | COLLATION(VERSION()) |
     +----------------------+
     | utf8_general_ci      |
     +----------------------+

For binary strings, the collation value is `binary', so comparisons
will be case sensitive. One context in which you will see `binary' is
for compression and encryption functions, which return binary strings
as a general rule: string:

     mysql> SELECT COLLATION(ENCRYPT('x')), COLLATION(SHA1('x'));
     +-------------------------+----------------------+
     | COLLATION(ENCRYPT('x')) | COLLATION(SHA1('x')) |
     +-------------------------+----------------------+
     | binary                  | binary               |
     +-------------------------+----------------------+

To check the sort value of a string, the `WEIGHT_STRING()' may be
helpful.  See *Note string-functions::.


File: manual.info,  Node: using-date,  Next: problems-with-null,  Prev: case-sensitivity,  Up: query-issues

B.1.5.2 Problems Using `DATE' Columns
.....................................

The format of a *Note `DATE': datetime. value is `'YYYY-MM-DD''.
According to standard SQL, no other format is allowed. You should use
this format in *Note `UPDATE': update. expressions and in the `WHERE'
clause of *Note `SELECT': select. statements. For example:

     mysql> SELECT * FROM TBL_NAME WHERE date >= '2003-05-05';

As a convenience, MySQL automatically converts a date to a number if
the date is used in a numeric context (and vice versa). It is also
smart enough to allow a `relaxed' string form when updating and in a
`WHERE' clause that compares a date to a *Note `TIMESTAMP': datetime,
*Note `DATE': datetime, or *Note `DATETIME': datetime. column.
(`Relaxed form' means that any punctuation character may be used as the
separator between parts. For example, `'2004-08-15'' and `'2004#08#15''
are equivalent.) MySQL can also convert a string containing no
separators (such as `'20040815''), provided it makes sense as a date.

When you compare a *Note `DATE': datetime, *Note `TIME': time, *Note
`DATETIME': datetime, or *Note `TIMESTAMP': datetime. to a constant
string with the `<', `<=', `=', `>=', `>', or `BETWEEN' operators,
MySQL normally converts the string to an internal long integer for
faster comparison (and also for a bit more `relaxed' string checking).
However, this conversion is subject to the following exceptions:

   * When you compare two columns

   * When you compare a *Note `DATE': datetime, *Note `TIME': time,
     *Note `DATETIME': datetime, or *Note `TIMESTAMP': datetime. column
     to an expression

   * When you use any other comparison method than those just listed,
     such as `IN' or `STRCMP()'.

For these exceptional cases, the comparison is done by converting the
objects to strings and performing a string comparison.

To keep things safe, assume that strings are compared as strings and
use the appropriate string functions if you want to compare a temporal
value to a string.

The special date `'0000-00-00'' can be stored and retrieved as
`'0000-00-00'.' When using a `'0000-00-00'' date through MyODBC, it is
automatically converted to `NULL' in MyODBC 2.50.12 and above, because
ODBC can't handle this kind of date.

Because MySQL performs the conversions described above, the following
statements work:

     mysql> INSERT INTO TBL_NAME (idate) VALUES (19970505);
     mysql> INSERT INTO TBL_NAME (idate) VALUES ('19970505');
     mysql> INSERT INTO TBL_NAME (idate) VALUES ('97-05-05');
     mysql> INSERT INTO TBL_NAME (idate) VALUES ('1997.05.05');
     mysql> INSERT INTO TBL_NAME (idate) VALUES ('1997 05 05');
     mysql> INSERT INTO TBL_NAME (idate) VALUES ('0000-00-00');

     mysql> SELECT idate FROM TBL_NAME WHERE idate >= '1997-05-05';
     mysql> SELECT idate FROM TBL_NAME WHERE idate >= 19970505;
     mysql> SELECT MOD(idate,100) FROM TBL_NAME WHERE idate >= 19970505;
     mysql> SELECT idate FROM TBL_NAME WHERE idate >= '19970505';

However, the following does not work:

     mysql> SELECT idate FROM TBL_NAME WHERE STRCMP(idate,'20030505')=0;

`STRCMP()' is a string function, so it converts `idate' to a string in
`'YYYY-MM-DD'' format and performs a string comparison. It does not
convert `'20030505'' to the date `'2003-05-05'' and perform a date
comparison.

If you are using the `ALLOW_INVALID_DATES' SQL mode, MySQL allows you
to store dates that are given only limited checking: MySQL requires
only that the day is in the range from 1 to 31 and the month is in the
range from 1 to 12.

This makes MySQL very convenient for Web applications where you obtain
year, month, and day in three different fields and you want to store
exactly what the user inserted (without date validation).

If you are not using the `NO_ZERO_IN_DATE' SQL mode, the day or month
part can be zero. This is convenient if you want to store a birthdate
in a *Note `DATE': datetime. column and you know only part of the date.

If you are not using the `NO_ZERO_DATE' SQL mode, MySQL also allows you
to store `'0000-00-00'' as a `dummy date.' This is in some cases more
convenient than using `NULL' values.

If the date cannot be converted to any reasonable value, a `0' is
stored in the *Note `DATE': datetime. column, which is retrieved as
`'0000-00-00''. This is both a speed and a convenience issue. We
believe that the database server's responsibility is to retrieve the
same date you stored (even if the data was not logically correct in all
cases). We think it is up to the application and not the server to
check the dates.

If you want MySQL to check all dates and accept only legal dates
(unless overridden by IGNORE), you should set `sql_mode' to
`"NO_ZERO_IN_DATE,NO_ZERO_DATE"'.


File: manual.info,  Node: problems-with-null,  Next: problems-with-alias,  Prev: using-date,  Up: query-issues

B.1.5.3 Problems with `NULL' Values
...................................

The concept of the `NULL' value is a common source of confusion for
newcomers to SQL, who often think that `NULL' is the same thing as an
empty string `'''. This is not the case. For example, the following
statements are completely different:

     mysql> INSERT INTO my_table (phone) VALUES (NULL);
     mysql> INSERT INTO my_table (phone) VALUES ('');

Both statements insert a value into the `phone' column, but the first
inserts a `NULL' value and the second inserts an empty string. The
meaning of the first can be regarded as `phone number is not known' and
the meaning of the second can be regarded as `the person is known to
have no phone, and thus no phone number.'

To help with `NULL' handling, you can use the `IS NULL' and `IS NOT
NULL' operators and the `IFNULL()' function.

In SQL, the `NULL' value is never true in comparison to any other
value, even `NULL'.  An expression that contains `NULL' always produces
a `NULL' value unless otherwise indicated in the documentation for the
operators and functions involved in the expression. All columns in the
following example return `NULL':

     mysql> SELECT NULL, 1+NULL, CONCAT('Invisible',NULL);

If you want to search for column values that are `NULL', you cannot use
an `expr = NULL' test. The following statement returns no rows, because
`expr = NULL' is never true for any expression:

     mysql> SELECT * FROM my_table WHERE phone = NULL;

To look for `NULL' values, you must use the `IS NULL' test. The
following statements show how to find the `NULL' phone number and the
empty phone number:

     mysql> SELECT * FROM my_table WHERE phone IS NULL;
     mysql> SELECT * FROM my_table WHERE phone = '';

See *Note working-with-null::, for additional information and examples.

You can add an index on a column that can have `NULL' values if you are
using the `MyISAM', `InnoDB', or `MEMORY' storage engine. Otherwise,
you must declare an indexed column `NOT NULL', and you cannot insert
`NULL' into the column.

When reading data with *Note `LOAD DATA INFILE': load-data, empty or
missing columns are updated with `'''. If you want a `NULL' value in a
column, you should use `\N' in the data file. The literal word ``NULL''
may also be used under some circumstances. See *Note load-data::.

When using `DISTINCT', `GROUP BY', or `ORDER BY', all `NULL' values are
regarded as equal.

When using `ORDER BY', `NULL' values are presented first, or last if
you specify `DESC' to sort in descending order.

Aggregate (summary) functions such as `COUNT()', `MIN()', and `SUM()'
ignore `NULL' values. The exception to this is `COUNT(*)', which counts
rows and not individual column values. For example, the following
statement produces two counts. The first is a count of the number of
rows in the table, and the second is a count of the number of
non-`NULL' values in the `age' column:

     mysql> SELECT COUNT(*), COUNT(age) FROM person;

For some data types, MySQL handles `NULL' values specially. If you
insert `NULL' into a *Note `TIMESTAMP': datetime. column, the current
date and time is inserted. If you insert `NULL' into an integer or
floating-point column that has the `AUTO_INCREMENT' attribute, the next
number in the sequence is inserted.


File: manual.info,  Node: problems-with-alias,  Next: non-transactional-tables,  Prev: problems-with-null,  Up: query-issues

B.1.5.4 Problems with Column Aliases
....................................

You can use an alias to refer to a column in `GROUP BY', `ORDER BY', or
`HAVING' clauses. Aliases can also be used to give columns better names:

     SELECT SQRT(a*b) AS root FROM TBL_NAME GROUP BY root HAVING root > 0;
     SELECT id, COUNT(*) AS cnt FROM TBL_NAME GROUP BY id HAVING cnt > 0;
     SELECT id AS 'Customer identity' FROM TBL_NAME;

Standard SQL doesn't allow you to refer to a column alias in a `WHERE'
clause. This restriction is imposed because when the `WHERE' code is
executed, the column value may not yet be determined. For example, the
following query is illegal:

     SELECT id, COUNT(*) AS cnt FROM TBL_NAME WHERE cnt > 0 GROUP BY id;

The `WHERE' statement is executed to determine which rows should be
included in the `GROUP BY' part, whereas `HAVING' is used to decide
which rows from the result set should be used.


File: manual.info,  Node: non-transactional-tables,  Next: deleting-from-related-tables,  Prev: problems-with-alias,  Up: query-issues

B.1.5.5 Rollback Failure for Non-Transactional Tables
.....................................................

If you receive the following message when trying to perform a *Note
`ROLLBACK': commit, it means that one or more of the tables you used in
the transaction do not support transactions:

     Warning: Some non-transactional changed tables couldn't be rolled back

These non-transactional tables are not affected by the *Note
`ROLLBACK': commit.  statement.

If you were not deliberately mixing transactional and non-transactional
tables within the transaction, the most likely cause for this message
is that a table you thought was transactional actually is not. This can
happen if you try to create a table using a transactional storage
engine that is not supported by your *Note `mysqld': mysqld. server (or
that was disabled with a startup option). If *Note `mysqld': mysqld.
doesn't support a storage engine, it instead creates the table as a
`MyISAM' table, which is non-transactional.

You can check the storage engine for a table by using either of these
statements:

     SHOW TABLE STATUS LIKE 'TBL_NAME';
     SHOW CREATE TABLE TBL_NAME;

See *Note show-table-status::, and *Note show-create-table::.

You can check which storage engines your *Note `mysqld': mysqld. server
supports by using this statement:

     SHOW ENGINES;

You can also use the following statement, and check the value of the
variable that is associated with the storage engine in which you are
interested:

     SHOW VARIABLES LIKE 'have_%';

For example, to determine whether the `InnoDB' storage engine is
available, check the value of the `have_innodb' variable.

See *Note show-engines::, and *Note show-variables::.

MySQL Enterprise

Ensure that your data is adequately protected by subscribing to the
MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: deleting-from-related-tables,  Next: no-matching-rows,  Prev: non-transactional-tables,  Up: query-issues

B.1.5.6 Deleting Rows from Related Tables
.........................................

If the total length of the *Note `DELETE': delete. statement for
`related_table' is more than 1MB (the default value of the
`max_allowed_packet' system variable), you should split it into smaller
parts and execute multiple *Note `DELETE': delete. statements. You
probably get the fastest *Note `DELETE': delete.  by specifying only
100 to 1,000 `related_column' values per statement if the
`related_column' is indexed. If the `related_column' isn't indexed, the
speed is independent of the number of arguments in the `IN' clause.


File: manual.info,  Node: no-matching-rows,  Next: problems-with-float,  Prev: deleting-from-related-tables,  Up: query-issues

B.1.5.7 Solving Problems with No Matching Rows
..............................................

If you have a complicated query that uses many tables but that doesn't
return any rows, you should use the following procedure to find out
what is wrong:

  1. Test the query with *Note `EXPLAIN': explain.  to check whether
     you can find something that is obviously wrong. See *Note
     explain::.

  2. Select only those columns that are used in the `WHERE' clause.

  3. Remove one table at a time from the query until it returns some
     rows. If the tables are large, it is a good idea to use `LIMIT 10'
     with the query.

  4. Issue a *Note `SELECT': select. for the column that should have
     matched a row against the table that was last removed from the
     query.

  5. If you are comparing *Note `FLOAT': numeric-types.  or *Note
     `DOUBLE': numeric-types. columns with numbers that have decimals,
     you can't use equality (`=') comparisons. This problem is common
     in most computer languages because not all floating-point values
     can be stored with exact precision. In some cases, changing the
     *Note `FLOAT': numeric-types. to a *Note `DOUBLE': numeric-types.
     fixes this. See *Note problems-with-float::.

  6. If you still can't figure out what is wrong, create a minimal test
     that can be run with `mysql test < query.sql' that shows your
     problems. You can create a test file by dumping the tables with
     *Note `mysqldump --quick db_name TBL_NAME_1 ... TBL_NAME_N >
     query.sql': mysqldump. Open the file in an editor, remove some
     insert lines (if there are more than needed to demonstrate the
     problem), and add your *Note `SELECT': select. statement at the end
     of the file.

     Verify that the test file demonstrates the problem by executing
     these commands:

          shell> mysqladmin create test2
          shell> mysql test2 < query.sql

     Attach the test file to a bug report, which you can file using the
     instructions in *Note bug-reports::.


File: manual.info,  Node: problems-with-float,  Prev: no-matching-rows,  Up: query-issues

B.1.5.8 Problems with Floating-Point Comparisons
................................................

Floating-point numbers sometimes cause confusion because they are
approximate. That is, they are not stored as exact values inside
computer architecture. What you can see on the screen usually is not
the exact value of the number. The *Note `FLOAT': numeric-types. and
*Note `DOUBLE': numeric-types. data types are such. For *Note
`DECIMAL': numeric-types. columns, MySQL performs operations with a
precision of 65 decimal digits, which should solve most common
inaccuracy problems.

The following example demonstrates the problem using *Note `DOUBLE':
numeric-types. It shows that are calculations that are done using
floating-point operations are subject to floating-point error.

     mysql> CREATE TABLE t1 (i INT, d1 DOUBLE, d2 DOUBLE);
     mysql> INSERT INTO t1 VALUES (1, 101.40, 21.40), (1, -80.00, 0.00),
         -> (2, 0.00, 0.00), (2, -13.20, 0.00), (2, 59.60, 46.40),
         -> (2, 30.40, 30.40), (3, 37.00, 7.40), (3, -29.60, 0.00),
         -> (4, 60.00, 15.40), (4, -10.60, 0.00), (4, -34.00, 0.00),
         -> (5, 33.00, 0.00), (5, -25.80, 0.00), (5, 0.00, 7.20),
         -> (6, 0.00, 0.00), (6, -51.40, 0.00);

     mysql> SELECT i, SUM(d1) AS a, SUM(d2) AS b
         -> FROM t1 GROUP BY i HAVING a <> b;

     +------+-------+------+
     | i    | a     | b    |
     +------+-------+------+
     |    1 |  21.4 | 21.4 |
     |    2 |  76.8 | 76.8 |
     |    3 |   7.4 |  7.4 |
     |    4 |  15.4 | 15.4 |
     |    5 |   7.2 |  7.2 |
     |    6 | -51.4 |    0 |
     +------+-------+------+

The result is correct. Although the first five records look like they
should not satisfy the comparison (the values of `a' and `b' do not
appear to be different), they may do so because the difference between
the numbers shows up around the tenth decimal or so, depending on
factors such as computer architecture or the compiler version or
optimization level. For example, different CPUs may evaluate
floating-point numbers differently.

If columns `d1' and `d2' had been defined as *Note `DECIMAL':
numeric-types. rather than *Note `DOUBLE': numeric-types, the result of
the *Note `SELECT': select. query would have contained only one row --
the last one shown above.

The correct way to do floating-point number comparison is to first
decide on an acceptable tolerance for differences between the numbers
and then do the comparison against the tolerance value. For example, if
we agree that floating-point numbers should be regarded the same if
they are same within a precision of one in ten thousand (0.0001), the
comparison should be written to find differences larger than the
tolerance value:

     mysql> SELECT i, SUM(d1) AS a, SUM(d2) AS b FROM t1
         -> GROUP BY i HAVING ABS(a - b) > 0.0001;
     +------+-------+------+
     | i    | a     | b    |
     +------+-------+------+
     |    6 | -51.4 |    0 |
     +------+-------+------+
     1 row in set (0.00 sec)

Conversely, to get rows where the numbers are the same, the test should
find differences within the tolerance value:

     mysql> SELECT i, SUM(d1) AS a, SUM(d2) AS b FROM t1
         -> GROUP BY i HAVING ABS(a - b) <= 0.0001;
     +------+------+------+
     | i    | a    | b    |
     +------+------+------+
     |    1 | 21.4 | 21.4 |
     |    2 | 76.8 | 76.8 |
     |    3 |  7.4 |  7.4 |
     |    4 | 15.4 | 15.4 |
     |    5 |  7.2 |  7.2 |
     +------+------+------+
     5 rows in set (0.03 sec)


File: manual.info,  Node: optimizer-issues,  Next: table-definition-issues,  Prev: query-issues,  Up: problems

B.1.6 Optimizer-Related Issues
------------------------------

MySQL uses a cost-based optimizer to determine the best way to resolve
a query. In many cases, MySQL can calculate the best possible query
plan, but sometimes MySQL doesn't have enough information about the
data at hand and has to make `educated' guesses about the data.

For the cases when MySQL does not do the "right" thing, tools that you
have available to help MySQL are:

   * Use the *Note `EXPLAIN': explain. statement to get information
     about how MySQL processes a query. To use it, just add the keyword
     *Note `EXPLAIN': explain. to the front of your *Note `SELECT':
     select. statement:

          mysql> EXPLAIN SELECT * FROM t1, t2 WHERE t1.i = t2.i;

     *Note `EXPLAIN': explain. is discussed in more detail in *Note
     explain::.

   * Use `ANALYZE TABLE TBL_NAME' to update the key distributions for
     the scanned table. See *Note analyze-table::.

   * Use `FORCE INDEX' for the scanned table to tell MySQL that table
     scans are very expensive compared to using the given index:

          SELECT * FROM t1, t2 FORCE INDEX (index_for_column)
          WHERE t1.col_name=t2.col_name;

     `USE INDEX' and `IGNORE INDEX' may also be useful. See *Note
     index-hints::.

   * Global and table-level `STRAIGHT_JOIN'. See *Note select::.

   * You can tune global or thread-specific system variables. For
     example, Start *Note `mysqld': mysqld. with the
     `--max-seeks-for-key=1000' option or use `SET
     max_seeks_for_key=1000' to tell the optimizer to assume that no
     key scan causes more than 1,000 key seeks. See *Note
     server-system-variables::.

MySQL Enterprise

For expert advice on configuring MySQL servers for optimal performance,
subscribe to the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: table-definition-issues,  Next: bugs,  Prev: optimizer-issues,  Up: problems

B.1.7 Table Definition-Related Issues
-------------------------------------

* Menu:

* alter-table-problems::         Problems with `ALTER TABLE'
* change-column-order::          How to Change the Order of Columns in a Table
* temporary-table-problems::     `TEMPORARY' Table Problems


File: manual.info,  Node: alter-table-problems,  Next: change-column-order,  Prev: table-definition-issues,  Up: table-definition-issues

B.1.7.1 Problems with `ALTER TABLE'
...................................

*Note `ALTER TABLE': alter-table. changes a table to the current
character set. If you get a duplicate-key error during *Note `ALTER
TABLE': alter-table, the cause is either that the new character sets
maps two keys to the same value or that the table is corrupted. In the
latter case, you should run *Note `REPAIR TABLE': repair-table. on the
table.

If *Note `ALTER TABLE': alter-table. dies with the following error, the
problem may be that MySQL crashed during an earlier *Note `ALTER
TABLE': alter-table.  operation and there is an old table named `A-XXX'
or `B-XXX' lying around:

     Error on rename of './database/name.frm'
     to './database/B-XXX.frm' (Errcode: 17)

In this case, go to the MySQL data directory and delete all files that
have names starting with `A-' or `B-'. (You may want to move them
elsewhere instead of deleting them.)

*Note `ALTER TABLE': alter-table. works in the following way:

   * Create a new table named `A-XXX' with the requested structural
     changes.

   * Copy all rows from the original table to `A-XXX'.

   * Rename the original table to `B-XXX'.

   * Rename `A-XXX' to your original table name.

   * Delete `B-XXX'.

If something goes wrong with the renaming operation, MySQL tries to
undo the changes. If something goes seriously wrong (although this
shouldn't happen), MySQL may leave the old table as `B-XXX'. A simple
rename of the table files at the system level should get your data back.

If you use *Note `ALTER TABLE': alter-table. on a transactional table
or if you are using Windows or OS/2, *Note `ALTER TABLE': alter-table.
unlocks the table if you had done a *Note `LOCK TABLE': lock-tables. on
it. This is done because `InnoDB' and these operating systems cannot
drop a table that is in use.


File: manual.info,  Node: change-column-order,  Next: temporary-table-problems,  Prev: alter-table-problems,  Up: table-definition-issues

B.1.7.2 How to Change the Order of Columns in a Table
.....................................................

First, consider whether you really need to change the column order in a
table. The whole point of SQL is to abstract the application from the
data storage format. You should always specify the order in which you
wish to retrieve your data. The first of the following statements
returns columns in the order COL_NAME1, COL_NAME2, COL_NAME3, whereas
the second returns them in the order COL_NAME1, COL_NAME3, COL_NAME2:

     mysql> SELECT COL_NAME1, COL_NAME2, COL_NAME3 FROM TBL_NAME;
     mysql> SELECT COL_NAME1, COL_NAME3, COL_NAME2 FROM TBL_NAME;

If you decide to change the order of table columns anyway, you can do
so as follows:

  1. Create a new table with the columns in the new order.

  2. Execute this statement:

          mysql> INSERT INTO new_table
              -> SELECT columns-in-new-order FROM old_table;

  3. Drop or rename `old_table'.

  4. Rename the new table to the original name:

          mysql> ALTER TABLE new_table RENAME old_table;

`SELECT *' is quite suitable for testing queries. However, in an
application, you should _never_ rely on using `SELECT *' and retrieving
the columns based on their position. The order and position in which
columns are returned does not remain the same if you add, move, or
delete columns.  A simple change to your table structure could cause
your application to fail.


File: manual.info,  Node: temporary-table-problems,  Prev: change-column-order,  Up: table-definition-issues

B.1.7.3 `TEMPORARY' Table Problems
..................................

The following list indicates limitations on the use of `TEMPORARY'
tables:

   * A `TEMPORARY' table can only be of type `MEMORY', `MyISAM',
     `MERGE', or `InnoDB'.

   * You cannot refer to a `TEMPORARY' table more than once in the same
     query. For example, the following does not work:

          mysql> SELECT * FROM temp_table, temp_table AS t2;
          ERROR 1137: Can't reopen table: 'temp_table'

     This error also occurs if you refer to a temporary table multiple
     times in a stored function under different aliases, even if the
     references occur in different statements within the function.

   * The *Note `SHOW TABLES': show-tables. statement does not list
     `TEMPORARY' tables.

   * You cannot use `RENAME' to rename a `TEMPORARY' table. However,
     you can use *Note `ALTER TABLE': alter-table. instead:

          mysql> ALTER TABLE orig_name RENAME new_name;

   * There are known issues in using temporary tables with replication.
     See *Note replication-features::, for more information.


File: manual.info,  Node: bugs,  Prev: table-definition-issues,  Up: problems

B.1.8 Known Issues in MySQL
---------------------------

* Menu:

* open-bugs::                    Open Issues in MySQL

This section is a list of the known issues in recent versions of MySQL.

For information about platform-specific issues, see the installation
and porting instructions in *Note operating-system-specific-notes::, and
MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).


File: manual.info,  Node: open-bugs,  Prev: bugs,  Up: bugs

B.1.8.1 Open Issues in MySQL
............................

The following problems are known and fixing them is a high priority:

   * Subquery optimization for `IN' is not as effective as for `='.

   * Even if you use `lower_case_table_names=2' (which enables MySQL to
     remember the case used for databases and table names), MySQL does
     not remember the case used for database names for the function
     `DATABASE()' or within the various logs (on case-insensitive
     systems).

   * Dropping a `FOREIGN KEY' constraint doesn't work in replication
     because the constraint may have another name on the slave.

   * *Note `REPLACE': replace. (and *Note `LOAD DATA': load-data. with
     the *Note `REPLACE': replace. option) does not trigger `ON DELETE
     CASCADE'.

   * `DISTINCT' with `ORDER BY' doesn't work inside `GROUP_CONCAT()' if
     you don't use all and only those columns that are in the
     `DISTINCT' list.

   * If one user has a long-running transaction and another user drops
     a table that is updated in the transaction, there is small chance
     that the binary log may contain the *Note `DROP TABLE':
     drop-table. command before the table is used in the transaction
     itself. We plan to fix this by having the *Note `DROP TABLE':
     drop-table. command wait until the table is not being used in any
     transaction.

   * When inserting a big integer value (between 2^63 and 2^64-1) into
     a decimal or string column, it is inserted as a negative value
     because the number is evaluated in a signed integer context.

   * *Note `FLUSH TABLES WITH READ LOCK': flush. does not block *Note
     `COMMIT': commit. if the server is running without binary logging,
     which may cause a problem (of consistency between tables) when
     doing a full backup.

   * *Note `ANALYZE TABLE': analyze-table, *Note `OPTIMIZE TABLE':
     optimize-table, and *Note `REPAIR TABLE': repair-table. may cause
     problems on tables for which you are using *Note `INSERT DELAYED':
     insert-delayed.

   * Performing `LOCK TABLE ...' and `FLUSH TABLES ...' doesn't
     guarantee that there isn't a half-finished transaction in progress
     on the table.

   * Replication uses query-level logging: The master writes the
     executed queries to the binary log. This is a very fast, compact,
     and efficient logging method that works perfectly in most cases.

     It is possible for the data on the master and slave to become
     different if a query is designed in such a way that the data
     modification is non-deterministic (generally not a recommended
     practice, even outside of replication).

     For example:

        * `CREATE ... SELECT' or *Note `INSERT ... SELECT':
          insert-select. statements that insert zero or `NULL' values
          into an `AUTO_INCREMENT' column.

        * *Note `DELETE': delete. if you are deleting rows from a table
          that has foreign keys with `ON DELETE CASCADE' properties.

        * `REPLACE ... SELECT', `INSERT IGNORE ... SELECT' if you have
          duplicate key values in the inserted data.

     *If and only if the preceding queries have no `ORDER BY' clause
     guaranteeing a deterministic order*.

     For example, for *Note `INSERT ... SELECT': insert-select. with no
     `ORDER BY', the *Note `SELECT': select. may return rows in a
     different order (which results in a row having different ranks,
     hence getting a different number in the `AUTO_INCREMENT' column),
     depending on the choices made by the optimizers on the master and
     slave.

     A query is optimized differently on the master and slave only if:

        * The table is stored using a different storage engine on the
          master than on the slave. (It is possible to use different
          storage engines on the master and slave.  For example, you
          can use `InnoDB' on the master, but `MyISAM' on the slave if
          the slave has less available disk space.)

        * MySQL buffer sizes (`key_buffer_size', and so on) are
          different on the master and slave.

        * The master and slave run different MySQL versions, and the
          optimizer code differs between these versions.

     This problem may also affect database restoration using
     `mysqlbinlog|mysql'.

     The easiest way to avoid this problem is to add an `ORDER BY'
     clause to the aforementioned non-deterministic queries to ensure
     that the rows are always stored or modified in the same order.

     In future MySQL versions, we will automatically add an `ORDER BY'
     clause when needed.

The following issues are known and will be fixed in due time:

   * Log file names are based on the server host name (if you don't
     specify a file name with the startup option). You have to use
     options such as `--log-bin=OLD_HOST_NAME-bin' if you change your
     host name to something else. Another option is to rename the old
     files to reflect your host name change (if these are binary logs,
     you need to edit the binary log index file and fix the binlog
     names there as well). See *Note server-options::.

   * *Note `mysqlbinlog': mysqlbinlog. does not delete temporary files
     left after a *Note `LOAD DATA INFILE': load-data. command. See
     *Note mysqlbinlog::.

   * `RENAME' doesn't work with `TEMPORARY' tables or tables used in a
     `MERGE' table.

   * Due to the way table format (`.frm') files are stored, you cannot
     use character 255 (`CHAR(255)') in table names, column names, or
     enumerations. This is scheduled to be fixed in version 5.1 when we
     implement new table definition format files.

   * When using `SET CHARACTER SET', you can't use translated
     characters in database, table, and column names.

   * You can't use ``_'' or ``%'' with `ESCAPE' in `LIKE ...  ESCAPE'.

   * You cannot build the server in another directory when using
     MIT-pthreads. Because this requires changes to MIT-pthreads, we
     are not likely to fix this. See *Note mit-pthreads::.

   * *Note `BLOB': blob. and *Note `TEXT': blob. values can't reliably
     be used in `GROUP BY', `ORDER BY' or `DISTINCT'. Only the first
     `max_sort_length' bytes are used when comparing *Note `BLOB':
     blob. values in these cases.  The default value of
     `max_sort_length' is 1024 and can be changed at server startup
     time or at runtime.

   * Numeric calculations are done with *Note `BIGINT': numeric-types.
     or *Note `DOUBLE': numeric-types. (both are normally 64 bits
     long). Which precision you get depends on the function. The
     general rule is that bit functions are performed with *Note
     `BIGINT': numeric-types.  precision, `IF()' and `ELT()' with *Note
     `BIGINT': numeric-types. or *Note `DOUBLE': numeric-types.
     precision, and the rest with *Note `DOUBLE': numeric-types.
     precision.  You should try to avoid using unsigned long long
     values if they resolve to be larger than 63 bits
     (9223372036854775807) for anything other than bit fields.

   * You can have up to 255 *Note `ENUM': enum.  and *Note `SET': set.
     columns in one table.

   * In `MIN()', `MAX()', and other aggregate functions, MySQL
     currently compares *Note `ENUM': enum. and *Note `SET': set.
     columns by their string value rather than by the string's relative
     position in the set.

   * *Note `mysqld_safe': mysqld-safe. redirects all messages from
     *Note `mysqld': mysqld. to the *Note `mysqld': mysqld.  log. One
     problem with this is that if you execute *Note `mysqladmin
     refresh': mysqladmin. to close and reopen the log, `stdout' and
     `stderr' are still redirected to the old log. If you use the
     general query log extensively, you should edit *Note
     `mysqld_safe': mysqld-safe. to log to `HOST_NAME.err' instead of
     `HOST_NAME.log' so that you can easily reclaim the space for the
     old log by deleting it and executing *Note `mysqladmin refresh':
     mysqladmin.

   * In an *Note `UPDATE': update. statement, columns are updated from
     left to right. If you refer to an updated column, you get the
     updated value instead of the original value. For example, the
     following statement increments `KEY' by `2', *not* `1':

          mysql> UPDATE TBL_NAME SET KEY=KEY+1,KEY=KEY+1;

   * You can refer to multiple temporary tables in the same query, but
     you cannot refer to any given temporary table more than once. For
     example, the following doesn't work:

          mysql> SELECT * FROM temp_table, temp_table AS t2;
          ERROR 1137: Can't reopen table: 'temp_table'

   * The optimizer may handle `DISTINCT' differently when you are using
     `hidden' columns in a join than when you are not. In a join, hidden
     columns are counted as part of the result (even if they are not
     shown), whereas in normal queries, hidden columns don't
     participate in the `DISTINCT' comparison. We will probably change
     this in the future to never compare the hidden columns when
     executing `DISTINCT'.

     An example of this is:

          SELECT DISTINCT mp3id FROM band_downloads
                 WHERE userid = 9 ORDER BY id DESC;

     and

          SELECT DISTINCT band_downloads.mp3id
                 FROM band_downloads,band_mp3
                 WHERE band_downloads.userid = 9
                 AND band_mp3.id = band_downloads.mp3id
                 ORDER BY band_downloads.id DESC;

     In the second case, using MySQL Server 3.23.x, you may get two
     identical rows in the result set (because the values in the hidden
     `id' column may differ).

     Note that this happens only for queries where that do not have the
     `ORDER BY' columns in the result.

   * If you execute a `PROCEDURE' on a query that returns an empty set,
     in some cases the `PROCEDURE' does not transform the columns.

   * Creation of a table of type `MERGE' doesn't check whether the
     underlying tables are compatible types.

   * If you use *Note `ALTER TABLE': alter-table. to add a `UNIQUE'
     index to a table used in a `MERGE' table and then add a normal
     index on the `MERGE' table, the key order is different for the
     tables if there was an old, non-`UNIQUE' key in the table. This is
     because *Note `ALTER TABLE': alter-table. puts `UNIQUE' indexes
     before normal indexes to be able to detect duplicate keys as early
     as possible.


File: manual.info,  Node: error-types,  Next: error-messages-server,  Prev: problems,  Up: error-handling

B.2 Types of Error Values
=========================

When an error occurs in MySQL, the server returns two types of error
values:

   * A MySQL-specific error code. This value is numeric. It is not
     portable to other database systems.

   * An SQLSTATE value. The value is a five-character string (for
     example, `'42S02''). The values are specified by ANSI SQL and ODBC
     and are more standardized.

When an error occurs, you can access the MySQL error code, the SQLSTATE
value, and a string containing an error message using C API functions:

   * MySQL error code: Call *Note `mysql_errno()': mysql-errno.

   * SQLSTATE value: Call *Note `mysql_sqlstate()': mysql-sqlstate.

   * Error message: Call *Note `mysql_error()': mysql-error.

For prepared statements, the corresponding error functions are *Note
`mysql_stmt_errno()': mysql-stmt-errno, *Note `mysql_stmt_sqlstate()':
mysql-stmt-sqlstate, and *Note `mysql_stmt_error()': mysql-stmt-error.
All error functions are described in *Note c::.

The first two characters of an SQLSTATE value indicate the error class:

   * `'00'' indicates success.

   * `'01'' indicates a warning.

   * `'02'' indicates `not found.' These values are relevant only
     within the context of cursors and are used to control what happens
     when a cursor reaches the end of a data set.

   * Other values indicate an exception.


File: manual.info,  Node: error-messages-server,  Next: error-messages-client,  Prev: error-types,  Up: error-handling

B.3 Server Error Codes and Messages
===================================

MySQL programs have access to several types of error information when
the server returns an error. For example, the *Note `mysql': mysql.
client program displays errors using the following format:

     shell> SELECT * FROM no_such_table;
     ERROR 1146 (42S02): Table 'test.no_such_table' doesn't exist

The message displayed contains three types of information:

   * A numeric error code (`1146'). This number is MySQL-specific and
     is not portable to other database systems.

   * A five-character SQLSTATE value (`'42S02'').  The values are
     specified by ANSI SQL and ODBC and are more standardized. Not all
     MySQL error numbers are mapped to SQLSTATE error codes. The value
     `'HY000'' (general error) is used for unmapped errors.

   * A string that provides a textual description of the error.

Server error information comes from the following source files.  For
details about the way that error information is defined, see the MySQL
Internals manual, available at `http://dev.mysql.com/doc/'.

   * Error message information is listed in the `share/errmsg.txt' file.
     `%d' and `%s' represent numbers and strings, respectively, that
     are substituted into the Message values when they are displayed.

   * The Error values listed in `share/errmsg.txt' are used to generate
     the definitions in the `include/mysqld_error.h' and
     `include/mysqld_ername.h' MySQL source files.

   * The SQLSTATE values listed in `share/errmsg.txt' are used to
     generate the definitions in the `include/sql_state.h' MySQL source
     file.

Because updates are frequent, it is possible that those files will
contain additional error information not listed here.

   * Error: `1000' SQLSTATE: `HY000' (`ER_HASHCHK')

     Message: hashchk

   * Error: `1001' SQLSTATE: `HY000' (`ER_NISAMCHK')

     Message: isamchk

   * Error: `1002' SQLSTATE: `HY000' (`ER_NO')

     Message: NO

   * Error: `1003' SQLSTATE: `HY000' (`ER_YES')

     Message: YES

   * Error: `1004' SQLSTATE: `HY000' (`ER_CANT_CREATE_FILE')

     Message: Can't create file '%s' (errno: %d)

   * Error: `1005' SQLSTATE: `HY000' (`ER_CANT_CREATE_TABLE')

     Message: Can't create table '%s' (errno: %d)

   * Error: `1006' SQLSTATE: `HY000' (`ER_CANT_CREATE_DB')

     Message: Can't create database '%s' (errno: %d)

   * Error: `1007' SQLSTATE: `HY000' (`ER_DB_CREATE_EXISTS')

     Message: Can't create database '%s'; database exists

   * Error: `1008' SQLSTATE: `HY000' (`ER_DB_DROP_EXISTS')

     Message: Can't drop database '%s'; database doesn't exist

   * Error: `1009' SQLSTATE: `HY000' (`ER_DB_DROP_DELETE')

     Message: Error dropping database (can't delete '%s', errno: %d)

   * Error: `1010' SQLSTATE: `HY000' (`ER_DB_DROP_RMDIR')

     Message: Error dropping database (can't rmdir '%s', errno: %d)

   * Error: `1011' SQLSTATE: `HY000' (`ER_CANT_DELETE_FILE')

     Message: Error on delete of '%s' (errno: %d)

   * Error: `1012' SQLSTATE: `HY000' (`ER_CANT_FIND_SYSTEM_REC')

     Message: Can't read record in system table

   * Error: `1013' SQLSTATE: `HY000' (`ER_CANT_GET_STAT')

     Message: Can't get status of '%s' (errno: %d)

   * Error: `1014' SQLSTATE: `HY000' (`ER_CANT_GET_WD')

     Message: Can't get working directory (errno: %d)

   * Error: `1015' SQLSTATE: `HY000' (`ER_CANT_LOCK')

     Message: Can't lock file (errno: %d)

   * Error: `1016' SQLSTATE: `HY000' (`ER_CANT_OPEN_FILE')

     Message: Can't open file: '%s' (errno: %d)

   * Error: `1017' SQLSTATE: `HY000' (`ER_FILE_NOT_FOUND')

     Message: Can't find file: '%s' (errno: %d)

   * Error: `1018' SQLSTATE: `HY000' (`ER_CANT_READ_DIR')

     Message: Can't read dir of '%s' (errno: %d)

   * Error: `1019' SQLSTATE: `HY000' (`ER_CANT_SET_WD')

     Message: Can't change dir to '%s' (errno: %d)

   * Error: `1020' SQLSTATE: `HY000' (`ER_CHECKREAD')

     Message: Record has changed since last read in table '%s'

   * Error: `1021' SQLSTATE: `HY000' (`ER_DISK_FULL')

     Message: Disk full (%s); waiting for someone to free some space...

   * Error: `1022' SQLSTATE: `23000' (`ER_DUP_KEY')

     Message: Can't write; duplicate key in table '%s'

   * Error: `1023' SQLSTATE: `HY000' (`ER_ERROR_ON_CLOSE')

     Message: Error on close of '%s' (errno: %d)

   * Error: `1024' SQLSTATE: `HY000' (`ER_ERROR_ON_READ')

     Message: Error reading file '%s' (errno: %d)

   * Error: `1025' SQLSTATE: `HY000' (`ER_ERROR_ON_RENAME')

     Message: Error on rename of '%s' to '%s' (errno: %d)

   * Error: `1026' SQLSTATE: `HY000' (`ER_ERROR_ON_WRITE')

     Message: Error writing file '%s' (errno: %d)

   * Error: `1027' SQLSTATE: `HY000' (`ER_FILE_USED')

     Message: '%s' is locked against change

   * Error: `1028' SQLSTATE: `HY000' (`ER_FILSORT_ABORT')

     Message: Sort aborted

   * Error: `1029' SQLSTATE: `HY000' (`ER_FORM_NOT_FOUND')

     Message: View '%s' doesn't exist for '%s'

   * Error: `1030' SQLSTATE: `HY000' (`ER_GET_ERRNO')

     Message: Got error %d from storage engine

   * Error: `1031' SQLSTATE: `HY000' (`ER_ILLEGAL_HA')

     Message: Table storage engine for '%s' doesn't have this option

   * Error: `1032' SQLSTATE: `HY000' (`ER_KEY_NOT_FOUND')

     Message: Can't find record in '%s'

   * Error: `1033' SQLSTATE: `HY000' (`ER_NOT_FORM_FILE')

     Message: Incorrect information in file: '%s'

   * Error: `1034' SQLSTATE: `HY000' (`ER_NOT_KEYFILE')

     Message: Incorrect key file for table '%s'; try to repair it

   * Error: `1035' SQLSTATE: `HY000' (`ER_OLD_KEYFILE')

     Message: Old key file for table '%s'; repair it!

   * Error: `1036' SQLSTATE: `HY000' (`ER_OPEN_AS_READONLY')

     Message: Table '%s' is read only

   * Error: `1037' SQLSTATE: `HY001' (`ER_OUTOFMEMORY')

     Message: Out of memory; restart server and try again (needed %d
     bytes)

   * Error: `1038' SQLSTATE: `HY001' (`ER_OUT_OF_SORTMEMORY')

     Message: Out of sort memory; increase server sort buffer size

   * Error: `1039' SQLSTATE: `HY000' (`ER_UNEXPECTED_EOF')

     Message: Unexpected EOF found when reading file '%s' (errno: %d)

   * Error: `1040' SQLSTATE: `08004' (`ER_CON_COUNT_ERROR')

     Message: Too many connections

   * Error: `1041' SQLSTATE: `HY000' (`ER_OUT_OF_RESOURCES')

     Message: Out of memory; check if mysqld or some other process uses
     all available memory; if not, you may have to use 'ulimit' to
     allow mysqld to use more memory or you can add more swap space

   * Error: `1042' SQLSTATE: `08S01' (`ER_BAD_HOST_ERROR')

     Message: Can't get hostname for your address

   * Error: `1043' SQLSTATE: `08S01' (`ER_HANDSHAKE_ERROR')

     Message: Bad handshake

   * Error: `1044' SQLSTATE: `42000' (`ER_DBACCESS_DENIED_ERROR')

     Message: Access denied for user '%s'@'%s' to database '%s'

   * Error: `1045' SQLSTATE: `28000' (`ER_ACCESS_DENIED_ERROR')

     Message: Access denied for user '%s'@'%s' (using password: %s)

   * Error: `1046' SQLSTATE: `3D000' (`ER_NO_DB_ERROR')

     Message: No database selected

   * Error: `1047' SQLSTATE: `08S01' (`ER_UNKNOWN_COM_ERROR')

     Message: Unknown command

   * Error: `1048' SQLSTATE: `23000' (`ER_BAD_NULL_ERROR')

     Message: Column '%s' cannot be null

   * Error: `1049' SQLSTATE: `42000' (`ER_BAD_DB_ERROR')

     Message: Unknown database '%s'

   * Error: `1050' SQLSTATE: `42S01' (`ER_TABLE_EXISTS_ERROR')

     Message: Table '%s' already exists

   * Error: `1051' SQLSTATE: `42S02' (`ER_BAD_TABLE_ERROR')

     Message: Unknown table '%s'

   * Error: `1052' SQLSTATE: `23000' (`ER_NON_UNIQ_ERROR')

     Message: Column '%s' in %s is ambiguous

   * Error: `1053' SQLSTATE: `08S01' (`ER_SERVER_SHUTDOWN')

     Message: Server shutdown in progress

   * Error: `1054' SQLSTATE: `42S22' (`ER_BAD_FIELD_ERROR')

     Message: Unknown column '%s' in '%s'

   * Error: `1055' SQLSTATE: `42000' (`ER_WRONG_FIELD_WITH_GROUP')

     Message: '%s' isn't in GROUP BY

   * Error: `1056' SQLSTATE: `42000' (`ER_WRONG_GROUP_FIELD')

     Message: Can't group on '%s'

   * Error: `1057' SQLSTATE: `42000' (`ER_WRONG_SUM_SELECT')

     Message: Statement has sum functions and columns in same statement

   * Error: `1058' SQLSTATE: `21S01' (`ER_WRONG_VALUE_COUNT')

     Message: Column count doesn't match value count

   * Error: `1059' SQLSTATE: `42000' (`ER_TOO_LONG_IDENT')

     Message: Identifier name '%s' is too long

   * Error: `1060' SQLSTATE: `42S21' (`ER_DUP_FIELDNAME')

     Message: Duplicate column name '%s'

   * Error: `1061' SQLSTATE: `42000' (`ER_DUP_KEYNAME')

     Message: Duplicate key name '%s'

   * Error: `1062' SQLSTATE: `23000' (`ER_DUP_ENTRY')

     Message: Duplicate entry '%s' for key %d

   * Error: `1063' SQLSTATE: `42000' (`ER_WRONG_FIELD_SPEC')

     Message: Incorrect column specifier for column '%s'

   * Error: `1064' SQLSTATE: `42000' (`ER_PARSE_ERROR')

     Message: %s near '%s' at line %d

   * Error: `1065' SQLSTATE: `42000' (`ER_EMPTY_QUERY')

     Message: Query was empty

   * Error: `1066' SQLSTATE: `42000' (`ER_NONUNIQ_TABLE')

     Message: Not unique table/alias: '%s'

   * Error: `1067' SQLSTATE: `42000' (`ER_INVALID_DEFAULT')

     Message: Invalid default value for '%s'

   * Error: `1068' SQLSTATE: `42000' (`ER_MULTIPLE_PRI_KEY')

     Message: Multiple primary key defined

   * Error: `1069' SQLSTATE: `42000' (`ER_TOO_MANY_KEYS')

     Message: Too many keys specified; max %d keys allowed

   * Error: `1070' SQLSTATE: `42000' (`ER_TOO_MANY_KEY_PARTS')

     Message: Too many key parts specified; max %d parts allowed

   * Error: `1071' SQLSTATE: `42000' (`ER_TOO_LONG_KEY')

     Message: Specified key was too long; max key length is %d bytes

   * Error: `1072' SQLSTATE: `42000' (`ER_KEY_COLUMN_DOES_NOT_EXITS')

     Message: Key column '%s' doesn't exist in table

   * Error: `1073' SQLSTATE: `42000' (`ER_BLOB_USED_AS_KEY')

     Message: BLOB column '%s' can't be used in key specification with
     the used table type

   * Error: `1074' SQLSTATE: `42000' (`ER_TOO_BIG_FIELDLENGTH')

     Message: Column length too big for column '%s' (max = %lu); use
     BLOB or TEXT instead

   * Error: `1075' SQLSTATE: `42000' (`ER_WRONG_AUTO_KEY')

     Message: Incorrect table definition; there can be only one auto
     column and it must be defined as a key

   * Error: `1076' SQLSTATE: `HY000' (`ER_READY')

     Message: %s: ready for connections. Version: '%s' socket: '%s'
     port: %d

   * Error: `1077' SQLSTATE: `HY000' (`ER_NORMAL_SHUTDOWN')

     Message: %s: Normal shutdown

   * Error: `1078' SQLSTATE: `HY000' (`ER_GOT_SIGNAL')

     Message: %s: Got signal %d. Aborting!

   * Error: `1079' SQLSTATE: `HY000' (`ER_SHUTDOWN_COMPLETE')

     Message: %s: Shutdown complete

   * Error: `1080' SQLSTATE: `08S01' (`ER_FORCING_CLOSE')

     Message: %s: Forcing close of thread %ld user: '%s'

   * Error: `1081' SQLSTATE: `08S01' (`ER_IPSOCK_ERROR')

     Message: Can't create IP socket

   * Error: `1082' SQLSTATE: `42S12' (`ER_NO_SUCH_INDEX')

     Message: Table '%s' has no index like the one used in CREATE
     INDEX; recreate the table

   * Error: `1083' SQLSTATE: `42000' (`ER_WRONG_FIELD_TERMINATORS')

     Message: Field separator argument is not what is expected; check
     the manual

   * Error: `1084' SQLSTATE: `42000' (`ER_BLOBS_AND_NO_TERMINATED')

     Message: You can't use fixed rowlength with BLOBs; please use
     'fields terminated by'

   * Error: `1085' SQLSTATE: `HY000' (`ER_TEXTFILE_NOT_READABLE')

     Message: The file '%s' must be in the database directory or be
     readable by all

   * Error: `1086' SQLSTATE: `HY000' (`ER_FILE_EXISTS_ERROR')

     Message: File '%s' already exists

   * Error: `1087' SQLSTATE: `HY000' (`ER_LOAD_INFO')

     Message: Records: %ld Deleted: %ld Skipped: %ld Warnings: %ld

   * Error: `1088' SQLSTATE: `HY000' (`ER_ALTER_INFO')

     Message: Records: %ld Duplicates: %ld

   * Error: `1089' SQLSTATE: `HY000' (`ER_WRONG_SUB_KEY')

     Message: Incorrect prefix key; the used key part isn't a string,
     the used length is longer than the key part, or the storage engine
     doesn't support unique prefix keys

   * Error: `1090' SQLSTATE: `42000' (`ER_CANT_REMOVE_ALL_FIELDS')

     Message: You can't delete all columns with ALTER TABLE; use DROP
     TABLE instead

   * Error: `1091' SQLSTATE: `42000' (`ER_CANT_DROP_FIELD_OR_KEY')

     Message: Can't DROP '%s'; check that column/key exists

   * Error: `1092' SQLSTATE: `HY000' (`ER_INSERT_INFO')

     Message: Records: %ld Duplicates: %ld Warnings: %ld

   * Error: `1093' SQLSTATE: `HY000' (`ER_UPDATE_TABLE_USED')

     Message: You can't specify target table '%s' for update in FROM
     clause

   * Error: `1094' SQLSTATE: `HY000' (`ER_NO_SUCH_THREAD')

     Message: Unknown thread id: %lu

   * Error: `1095' SQLSTATE: `HY000' (`ER_KILL_DENIED_ERROR')

     Message: You are not owner of thread %lu

   * Error: `1096' SQLSTATE: `HY000' (`ER_NO_TABLES_USED')

     Message: No tables used

   * Error: `1097' SQLSTATE: `HY000' (`ER_TOO_BIG_SET')

     Message: Too many strings for column %s and SET

   * Error: `1098' SQLSTATE: `HY000' (`ER_NO_UNIQUE_LOGFILE')

     Message: Can't generate a unique log-filename %s.(1-999)

   * Error: `1099' SQLSTATE: `HY000' (`ER_TABLE_NOT_LOCKED_FOR_WRITE')

     Message: Table '%s' was locked with a READ lock and can't be
     updated

   * Error: `1100' SQLSTATE: `HY000' (`ER_TABLE_NOT_LOCKED')

     Message: Table '%s' was not locked with LOCK TABLES

   * Error: `1101' SQLSTATE: `42000' (`ER_BLOB_CANT_HAVE_DEFAULT')

     Message: BLOB/TEXT column '%s' can't have a default value

   * Error: `1102' SQLSTATE: `42000' (`ER_WRONG_DB_NAME')

     Message: Incorrect database name '%s'

   * Error: `1103' SQLSTATE: `42000' (`ER_WRONG_TABLE_NAME')

     Message: Incorrect table name '%s'

   * Error: `1104' SQLSTATE: `42000' (`ER_TOO_BIG_SELECT')

     Message: The SELECT would examine more than MAX_JOIN_SIZE rows;
     check your WHERE and use SET SQL_BIG_SELECTS=1 or SET
     SQL_MAX_JOIN_SIZE=# if the SELECT is okay

   * Error: `1105' SQLSTATE: `HY000' (`ER_UNKNOWN_ERROR')

     Message: Unknown error

   * Error: `1106' SQLSTATE: `42000' (`ER_UNKNOWN_PROCEDURE')

     Message: Unknown procedure '%s'

   * Error: `1107' SQLSTATE: `42000'
     (`ER_WRONG_PARAMCOUNT_TO_PROCEDURE')

     Message: Incorrect parameter count to procedure '%s'

   * Error: `1108' SQLSTATE: `HY000'
     (`ER_WRONG_PARAMETERS_TO_PROCEDURE')

     Message: Incorrect parameters to procedure '%s'

   * Error: `1109' SQLSTATE: `42S02' (`ER_UNKNOWN_TABLE')

     Message: Unknown table '%s' in %s

   * Error: `1110' SQLSTATE: `42000' (`ER_FIELD_SPECIFIED_TWICE')

     Message: Column '%s' specified twice

   * Error: `1111' SQLSTATE: `HY000' (`ER_INVALID_GROUP_FUNC_USE')

     Message: Invalid use of group function

   * Error: `1112' SQLSTATE: `42000' (`ER_UNSUPPORTED_EXTENSION')

     Message: Table '%s' uses an extension that doesn't exist in this
     MySQL version

   * Error: `1113' SQLSTATE: `42000' (`ER_TABLE_MUST_HAVE_COLUMNS')

     Message: A table must have at least 1 column

   * Error: `1114' SQLSTATE: `HY000' (`ER_RECORD_FILE_FULL')

     Message: The table '%s' is full

   * Error: `1115' SQLSTATE: `42000' (`ER_UNKNOWN_CHARACTER_SET')

     Message: Unknown character set: '%s'

   * Error: `1116' SQLSTATE: `HY000' (`ER_TOO_MANY_TABLES')

     Message: Too many tables; MySQL can only use %d tables in a join

   * Error: `1117' SQLSTATE: `HY000' (`ER_TOO_MANY_FIELDS')

     Message: Too many columns

   * Error: `1118' SQLSTATE: `42000' (`ER_TOO_BIG_ROWSIZE')

     Message: Row size too large. The maximum row size for the used
     table type, not counting BLOBs, is %ld. You have to change some
     columns to TEXT or BLOBs

   * Error: `1119' SQLSTATE: `HY000' (`ER_STACK_OVERRUN')

     Message: Thread stack overrun: Used: %ld of a %ld stack. Use
     'mysqld -O thread_stack=#' to specify a bigger stack if needed

   * Error: `1120' SQLSTATE: `42000' (`ER_WRONG_OUTER_JOIN')

     Message: Cross dependency found in OUTER JOIN; examine your ON
     conditions

   * Error: `1121' SQLSTATE: `42000' (`ER_NULL_COLUMN_IN_INDEX')

     Message: Table handler doesn't support NULL in given index. Please
     change column '%s' to be NOT NULL or use another handler

   * Error: `1122' SQLSTATE: `HY000' (`ER_CANT_FIND_UDF')

     Message: Can't load function '%s'

   * Error: `1123' SQLSTATE: `HY000' (`ER_CANT_INITIALIZE_UDF')

     Message: Can't initialize function '%s'; %s

   * Error: `1124' SQLSTATE: `HY000' (`ER_UDF_NO_PATHS')

     Message: No paths allowed for shared library

   * Error: `1125' SQLSTATE: `HY000' (`ER_UDF_EXISTS')

     Message: Function '%s' already exists

   * Error: `1126' SQLSTATE: `HY000' (`ER_CANT_OPEN_LIBRARY')

     Message: Can't open shared library '%s' (errno: %d %s)

   * Error: `1127' SQLSTATE: `HY000' (`ER_CANT_FIND_DL_ENTRY')

     Message: Can't find symbol '%s' in library

   * Error: `1128' SQLSTATE: `HY000' (`ER_FUNCTION_NOT_DEFINED')

     Message: Function '%s' is not defined

   * Error: `1129' SQLSTATE: `HY000' (`ER_HOST_IS_BLOCKED')

     Message: Host '%s' is blocked because of many connection errors;
     unblock with 'mysqladmin flush-hosts'

   * Error: `1130' SQLSTATE: `HY000' (`ER_HOST_NOT_PRIVILEGED')

     Message: Host '%s' is not allowed to connect to this MySQL server

   * Error: `1131' SQLSTATE: `42000' (`ER_PASSWORD_ANONYMOUS_USER')

     Message: You are using MySQL as an anonymous user and anonymous
     users are not allowed to change passwords

   * Error: `1132' SQLSTATE: `42000' (`ER_PASSWORD_NOT_ALLOWED')

     Message: You must have privileges to update tables in the mysql
     database to be able to change passwords for others

   * Error: `1133' SQLSTATE: `42000' (`ER_PASSWORD_NO_MATCH')

     Message: Can't find any matching row in the user table

   * Error: `1134' SQLSTATE: `HY000' (`ER_UPDATE_INFO')

     Message: Rows matched: %ld Changed: %ld Warnings: %ld

   * Error: `1135' SQLSTATE: `HY000' (`ER_CANT_CREATE_THREAD')

     Message: Can't create a new thread (errno %d); if you are not out
     of available memory, you can consult the manual for a possible
     OS-dependent bug

   * Error: `1136' SQLSTATE: `21S01' (`ER_WRONG_VALUE_COUNT_ON_ROW')

     Message: Column count doesn't match value count at row %ld

   * Error: `1137' SQLSTATE: `HY000' (`ER_CANT_REOPEN_TABLE')

     Message: Can't reopen table: '%s'

   * Error: `1138' SQLSTATE: `22004' (`ER_INVALID_USE_OF_NULL')

     Message: Invalid use of NULL value

   * Error: `1139' SQLSTATE: `42000' (`ER_REGEXP_ERROR')

     Message: Got error '%s' from regexp

   * Error: `1140' SQLSTATE: `42000' (`ER_MIX_OF_GROUP_FUNC_AND_FIELDS')

     Message: Mixing of GROUP columns (MIN(),MAX(),COUNT(),...) with no
     GROUP columns is illegal if there is no GROUP BY clause

   * Error: `1141' SQLSTATE: `42000' (`ER_NONEXISTING_GRANT')

     Message: There is no such grant defined for user '%s' on host '%s'

   * Error: `1142' SQLSTATE: `42000' (`ER_TABLEACCESS_DENIED_ERROR')

     Message: %s command denied to user '%s'@'%s' for table '%s'

   * Error: `1143' SQLSTATE: `42000' (`ER_COLUMNACCESS_DENIED_ERROR')

     Message: %s command denied to user '%s'@'%s' for column '%s' in
     table '%s'

   * Error: `1144' SQLSTATE: `42000' (`ER_ILLEGAL_GRANT_FOR_TABLE')

     Message: Illegal GRANT/REVOKE command; please consult the manual
     to see which privileges can be used

   * Error: `1145' SQLSTATE: `42000' (`ER_GRANT_WRONG_HOST_OR_USER')

     Message: The host or user argument to GRANT is too long

   * Error: `1146' SQLSTATE: `42S02' (`ER_NO_SUCH_TABLE')

     Message: Table '%s.%s' doesn't exist

   * Error: `1147' SQLSTATE: `42000' (`ER_NONEXISTING_TABLE_GRANT')

     Message: There is no such grant defined for user '%s' on host '%s'
     on table '%s'

   * Error: `1148' SQLSTATE: `42000' (`ER_NOT_ALLOWED_COMMAND')

     Message: The used command is not allowed with this MySQL version

   * Error: `1149' SQLSTATE: `42000' (`ER_SYNTAX_ERROR')

     Message: You have an error in your SQL syntax; check the manual
     that corresponds to your MySQL server version for the right syntax
     to use

   * Error: `1150' SQLSTATE: `HY000' (`ER_DELAYED_CANT_CHANGE_LOCK')

     Message: Delayed insert thread couldn't get requested lock for
     table %s

   * Error: `1151' SQLSTATE: `HY000' (`ER_TOO_MANY_DELAYED_THREADS')

     Message: Too many delayed threads in use

   * Error: `1152' SQLSTATE: `08S01' (`ER_ABORTING_CONNECTION')

     Message: Aborted connection %ld to db: '%s' user: '%s' (%s)

   * Error: `1153' SQLSTATE: `08S01' (`ER_NET_PACKET_TOO_LARGE')

     Message: Got a packet bigger than 'max_allowed_packet' bytes

   * Error: `1154' SQLSTATE: `08S01' (`ER_NET_READ_ERROR_FROM_PIPE')

     Message: Got a read error from the connection pipe

   * Error: `1155' SQLSTATE: `08S01' (`ER_NET_FCNTL_ERROR')

     Message: Got an error from fcntl()

   * Error: `1156' SQLSTATE: `08S01' (`ER_NET_PACKETS_OUT_OF_ORDER')

     Message: Got packets out of order

   * Error: `1157' SQLSTATE: `08S01' (`ER_NET_UNCOMPRESS_ERROR')

     Message: Couldn't uncompress communication packet

   * Error: `1158' SQLSTATE: `08S01' (`ER_NET_READ_ERROR')

     Message: Got an error reading communication packets

   * Error: `1159' SQLSTATE: `08S01' (`ER_NET_READ_INTERRUPTED')

     Message: Got timeout reading communication packets

   * Error: `1160' SQLSTATE: `08S01' (`ER_NET_ERROR_ON_WRITE')

     Message: Got an error writing communication packets

   * Error: `1161' SQLSTATE: `08S01' (`ER_NET_WRITE_INTERRUPTED')

     Message: Got timeout writing communication packets

   * Error: `1162' SQLSTATE: `42000' (`ER_TOO_LONG_STRING')

     Message: Result string is longer than 'max_allowed_packet' bytes

   * Error: `1163' SQLSTATE: `42000' (`ER_TABLE_CANT_HANDLE_BLOB')

     Message: The used table type doesn't support BLOB/TEXT columns

   * Error: `1164' SQLSTATE: `42000'
     (`ER_TABLE_CANT_HANDLE_AUTO_INCREMENT')

     Message: The used table type doesn't support AUTO_INCREMENT columns

   * Error: `1165' SQLSTATE: `HY000' (`ER_DELAYED_INSERT_TABLE_LOCKED')

     Message: INSERT DELAYED can't be used with table '%s' because it
     is locked with LOCK TABLES

   * Error: `1166' SQLSTATE: `42000' (`ER_WRONG_COLUMN_NAME')

     Message: Incorrect column name '%s'

   * Error: `1167' SQLSTATE: `42000' (`ER_WRONG_KEY_COLUMN')

     Message: The used storage engine can't index column '%s'

   * Error: `1168' SQLSTATE: `HY000' (`ER_WRONG_MRG_TABLE')

     Message: Unable to open underlying table which is differently
     defined or of non-MyISAM type or doesn't exist

   * Error: `1169' SQLSTATE: `23000' (`ER_DUP_UNIQUE')

     Message: Can't write, because of unique constraint, to table '%s'

   * Error: `1170' SQLSTATE: `42000' (`ER_BLOB_KEY_WITHOUT_LENGTH')

     Message: BLOB/TEXT column '%s' used in key specification without a
     key length

   * Error: `1171' SQLSTATE: `42000' (`ER_PRIMARY_CANT_HAVE_NULL')

     Message: All parts of a PRIMARY KEY must be NOT NULL; if you need
     NULL in a key, use UNIQUE instead

   * Error: `1172' SQLSTATE: `42000' (`ER_TOO_MANY_ROWS')

     Message: Result consisted of more than one row

   * Error: `1173' SQLSTATE: `42000' (`ER_REQUIRES_PRIMARY_KEY')

     Message: This table type requires a primary key

   * Error: `1174' SQLSTATE: `HY000' (`ER_NO_RAID_COMPILED')

     Message: This version of MySQL is not compiled with RAID support

   * Error: `1175' SQLSTATE: `HY000'
     (`ER_UPDATE_WITHOUT_KEY_IN_SAFE_MODE')

     Message: You are using safe update mode and you tried to update a
     table without a WHERE that uses a KEY column

   * Error: `1176' SQLSTATE: `42000' (`ER_KEY_DOES_NOT_EXITS')

     Message: Key '%s' doesn't exist in table '%s'

   * Error: `1177' SQLSTATE: `42000' (`ER_CHECK_NO_SUCH_TABLE')

     Message: Can't open table

   * Error: `1178' SQLSTATE: `42000' (`ER_CHECK_NOT_IMPLEMENTED')

     Message: The storage engine for the table doesn't support %s

   * Error: `1179' SQLSTATE: `25000'
     (`ER_CANT_DO_THIS_DURING_AN_TRANSACTION')

     Message: You are not allowed to execute this command in a
     transaction

   * Error: `1180' SQLSTATE: `HY000' (`ER_ERROR_DURING_COMMIT')

     Message: Got error %d during COMMIT

   * Error: `1181' SQLSTATE: `HY000' (`ER_ERROR_DURING_ROLLBACK')

     Message: Got error %d during ROLLBACK

   * Error: `1182' SQLSTATE: `HY000' (`ER_ERROR_DURING_FLUSH_LOGS')

     Message: Got error %d during FLUSH_LOGS

   * Error: `1183' SQLSTATE: `HY000' (`ER_ERROR_DURING_CHECKPOINT')

     Message: Got error %d during CHECKPOINT

   * Error: `1184' SQLSTATE: `08S01' (`ER_NEW_ABORTING_CONNECTION')

     Message: Aborted connection %ld to db: '%s' user: '%s' host: '%s'
     (%s)

   * Error: `1185' SQLSTATE: `HY000' (`ER_DUMP_NOT_IMPLEMENTED')

     Message: The storage engine for the table does not support binary
     table dump

   * Error: `1186' SQLSTATE: `HY000' (`ER_FLUSH_MASTER_BINLOG_CLOSED')

     Message: Binlog closed, cannot RESET MASTER

   * Error: `1187' SQLSTATE: `HY000' (`ER_INDEX_REBUILD')

     Message: Failed rebuilding the index of dumped table '%s'

   * Error: `1188' SQLSTATE: `HY000' (`ER_MASTER')

     Message: Error from master: '%s'

   * Error: `1189' SQLSTATE: `08S01' (`ER_MASTER_NET_READ')

     Message: Net error reading from master

   * Error: `1190' SQLSTATE: `08S01' (`ER_MASTER_NET_WRITE')

     Message: Net error writing to master

   * Error: `1191' SQLSTATE: `HY000' (`ER_FT_MATCHING_KEY_NOT_FOUND')

     Message: Can't find FULLTEXT index matching the column list

   * Error: `1192' SQLSTATE: `HY000' (`ER_LOCK_OR_ACTIVE_TRANSACTION')

     Message: Can't execute the given command because you have active
     locked tables or an active transaction

   * Error: `1193' SQLSTATE: `HY000' (`ER_UNKNOWN_SYSTEM_VARIABLE')

     Message: Unknown system variable '%s'

   * Error: `1194' SQLSTATE: `HY000' (`ER_CRASHED_ON_USAGE')

     Message: Table '%s' is marked as crashed and should be repaired

   * Error: `1195' SQLSTATE: `HY000' (`ER_CRASHED_ON_REPAIR')

     Message: Table '%s' is marked as crashed and last (automatic?)
     repair failed

   * Error: `1196' SQLSTATE: `HY000'
     (`ER_WARNING_NOT_COMPLETE_ROLLBACK')

     Message: Some non-transactional changed tables couldn't be rolled
     back

   * Error: `1197' SQLSTATE: `HY000' (`ER_TRANS_CACHE_FULL')

     Message: Multi-statement transaction required more than
     'max_binlog_cache_size' bytes of storage; increase this mysqld
     variable and try again

   * Error: `1198' SQLSTATE: `HY000' (`ER_SLAVE_MUST_STOP')

     Message: This operation cannot be performed with a running slave;
     run STOP SLAVE first

   * Error: `1199' SQLSTATE: `HY000' (`ER_SLAVE_NOT_RUNNING')

     Message: This operation requires a running slave; configure slave
     and do START SLAVE

   * Error: `1200' SQLSTATE: `HY000' (`ER_BAD_SLAVE')

     Message: The server is not configured as slave; fix with CHANGE
     MASTER TO

   * Error: `1201' SQLSTATE: `HY000' (`ER_MASTER_INFO')

     Message: Could not initialize master info structure; more error
     messages can be found in the MySQL error log

   * Error: `1202' SQLSTATE: `HY000' (`ER_SLAVE_THREAD')

     Message: Could not create slave thread; check system resources

   * Error: `1203' SQLSTATE: `42000' (`ER_TOO_MANY_USER_CONNECTIONS')

     Message: User %s already has more than 'max_user_connections'
     active connections

   * Error: `1204' SQLSTATE: `HY000' (`ER_SET_CONSTANTS_ONLY')

     Message: You may only use constant expressions with SET

   * Error: `1205' SQLSTATE: `HY000' (`ER_LOCK_WAIT_TIMEOUT')

     Message: Lock wait timeout exceeded; try restarting transaction

   * Error: `1206' SQLSTATE: `HY000' (`ER_LOCK_TABLE_FULL')

     Message: The total number of locks exceeds the lock table size

   * Error: `1207' SQLSTATE: `25000' (`ER_READ_ONLY_TRANSACTION')

     Message: Update locks cannot be acquired during a READ UNCOMMITTED
     transaction

   * Error: `1208' SQLSTATE: `HY000' (`ER_DROP_DB_WITH_READ_LOCK')

     Message: DROP DATABASE not allowed while thread is holding global
     read lock

   * Error: `1209' SQLSTATE: `HY000' (`ER_CREATE_DB_WITH_READ_LOCK')

     Message: CREATE DATABASE not allowed while thread is holding
     global read lock

   * Error: `1210' SQLSTATE: `HY000' (`ER_WRONG_ARGUMENTS')

     Message: Incorrect arguments to %s

   * Error: `1211' SQLSTATE: `42000' (`ER_NO_PERMISSION_TO_CREATE_USER')

     Message: '%s'@'%s' is not allowed to create new users

   * Error: `1212' SQLSTATE: `HY000'
     (`ER_UNION_TABLES_IN_DIFFERENT_DIR')

     Message: Incorrect table definition; all MERGE tables must be in
     the same database

   * Error: `1213' SQLSTATE: `40001' (`ER_LOCK_DEADLOCK')

     Message: Deadlock found when trying to get lock; try restarting
     transaction

   * Error: `1214' SQLSTATE: `HY000' (`ER_TABLE_CANT_HANDLE_FT')

     Message: The used table type doesn't support FULLTEXT indexes

   * Error: `1215' SQLSTATE: `HY000' (`ER_CANNOT_ADD_FOREIGN')

     Message: Cannot add foreign key constraint

   * Error: `1216' SQLSTATE: `23000' (`ER_NO_REFERENCED_ROW')

     Message: Cannot add or update a child row: a foreign key
     constraint fails

   * Error: `1217' SQLSTATE: `23000' (`ER_ROW_IS_REFERENCED')

     Message: Cannot delete or update a parent row: a foreign key
     constraint fails

   * Error: `1218' SQLSTATE: `08S01' (`ER_CONNECT_TO_MASTER')

     Message: Error connecting to master: %s

   * Error: `1219' SQLSTATE: `HY000' (`ER_QUERY_ON_MASTER')

     Message: Error running query on master: %s

   * Error: `1220' SQLSTATE: `HY000' (`ER_ERROR_WHEN_EXECUTING_COMMAND')

     Message: Error when executing command %s: %s

   * Error: `1221' SQLSTATE: `HY000' (`ER_WRONG_USAGE')

     Message: Incorrect usage of %s and %s

   * Error: `1222' SQLSTATE: `21000'
     (`ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT')

     Message: The used SELECT statements have a different number of
     columns

   * Error: `1223' SQLSTATE: `HY000' (`ER_CANT_UPDATE_WITH_READLOCK')

     Message: Can't execute the query because you have a conflicting
     read lock

   * Error: `1224' SQLSTATE: `HY000' (`ER_MIXING_NOT_ALLOWED')

     Message: Mixing of transactional and non-transactional tables is
     disabled

   * Error: `1225' SQLSTATE: `HY000' (`ER_DUP_ARGUMENT')

     Message: Option '%s' used twice in statement

   * Error: `1226' SQLSTATE: `42000' (`ER_USER_LIMIT_REACHED')

     Message: User '%s' has exceeded the '%s' resource (current value:
     %ld)

   * Error: `1227' SQLSTATE: `42000' (`ER_SPECIFIC_ACCESS_DENIED_ERROR')

     Message: Access denied; you need the %s privilege for this
     operation

   * Error: `1228' SQLSTATE: `HY000' (`ER_LOCAL_VARIABLE')

     Message: Variable '%s' is a SESSION variable and can't be used
     with SET GLOBAL

   * Error: `1229' SQLSTATE: `HY000' (`ER_GLOBAL_VARIABLE')

     Message: Variable '%s' is a GLOBAL variable and should be set with
     SET GLOBAL

   * Error: `1230' SQLSTATE: `42000' (`ER_NO_DEFAULT')

     Message: Variable '%s' doesn't have a default value

   * Error: `1231' SQLSTATE: `42000' (`ER_WRONG_VALUE_FOR_VAR')

     Message: Variable '%s' can't be set to the value of '%s'

   * Error: `1232' SQLSTATE: `42000' (`ER_WRONG_TYPE_FOR_VAR')

     Message: Incorrect argument type to variable '%s'

   * Error: `1233' SQLSTATE: `HY000' (`ER_VAR_CANT_BE_READ')

     Message: Variable '%s' can only be set, not read

   * Error: `1234' SQLSTATE: `42000' (`ER_CANT_USE_OPTION_HERE')

     Message: Incorrect usage/placement of '%s'

   * Error: `1235' SQLSTATE: `42000' (`ER_NOT_SUPPORTED_YET')

     Message: This version of MySQL doesn't yet support '%s'

   * Error: `1236' SQLSTATE: `HY000'
     (`ER_MASTER_FATAL_ERROR_READING_BINLOG')

     Message: Got fatal error %d: '%s' from master when reading data
     from binary log

   * Error: `1237' SQLSTATE: `HY000' (`ER_SLAVE_IGNORED_TABLE')

     Message: Slave SQL thread ignored the query because of
     replicate-*-table rules

   * Error: `1238' SQLSTATE: `HY000' (`ER_INCORRECT_GLOBAL_LOCAL_VAR')

     Message: Variable '%s' is a %s variable

   * Error: `1239' SQLSTATE: `42000' (`ER_WRONG_FK_DEF')

     Message: Incorrect foreign key definition for '%s': %s

   * Error: `1240' SQLSTATE: `HY000'
     (`ER_KEY_REF_DO_NOT_MATCH_TABLE_REF')

     Message: Key reference and table reference don't match

   * Error: `1241' SQLSTATE: `21000' (`ER_OPERAND_COLUMNS')

     Message: Operand should contain %d column(s)

   * Error: `1242' SQLSTATE: `21000' (`ER_SUBQUERY_NO_1_ROW')

     Message: Subquery returns more than 1 row

   * Error: `1243' SQLSTATE: `HY000' (`ER_UNKNOWN_STMT_HANDLER')

     Message: Unknown prepared statement handler (%.*s) given to %s

   * Error: `1244' SQLSTATE: `HY000' (`ER_CORRUPT_HELP_DB')

     Message: Help database is corrupt or does not exist

   * Error: `1245' SQLSTATE: `HY000' (`ER_CYCLIC_REFERENCE')

     Message: Cyclic reference on subqueries

   * Error: `1246' SQLSTATE: `HY000' (`ER_AUTO_CONVERT')

     Message: Converting column '%s' from %s to %s

   * Error: `1247' SQLSTATE: `42S22' (`ER_ILLEGAL_REFERENCE')

     Message: Reference '%s' not supported (%s)

   * Error: `1248' SQLSTATE: `42000' (`ER_DERIVED_MUST_HAVE_ALIAS')

     Message: Every derived table must have its own alias

   * Error: `1249' SQLSTATE: `01000' (`ER_SELECT_REDUCED')

     Message: Select %u was reduced during optimization

   * Error: `1250' SQLSTATE: `42000' (`ER_TABLENAME_NOT_ALLOWED_HERE')

     Message: Table '%s' from one of the SELECTs cannot be used in %s

   * Error: `1251' SQLSTATE: `08004' (`ER_NOT_SUPPORTED_AUTH_MODE')

     Message: Client does not support authentication protocol requested
     by server; consider upgrading MySQL client

   * Error: `1252' SQLSTATE: `42000' (`ER_SPATIAL_CANT_HAVE_NULL')

     Message: All parts of a SPATIAL index must be NOT NULL

   * Error: `1253' SQLSTATE: `42000' (`ER_COLLATION_CHARSET_MISMATCH')

     Message: COLLATION '%s' is not valid for CHARACTER SET '%s'

   * Error: `1254' SQLSTATE: `HY000' (`ER_SLAVE_WAS_RUNNING')

     Message: Slave is already running

   * Error: `1255' SQLSTATE: `HY000' (`ER_SLAVE_WAS_NOT_RUNNING')

     Message: Slave already has been stopped

   * Error: `1256' SQLSTATE: `HY000' (`ER_TOO_BIG_FOR_UNCOMPRESS')

     Message: Uncompressed data size too large; the maximum size is %d
     (probably, length of uncompressed data was corrupted)

   * Error: `1257' SQLSTATE: `HY000' (`ER_ZLIB_Z_MEM_ERROR')

     Message: ZLIB: Not enough memory

   * Error: `1258' SQLSTATE: `HY000' (`ER_ZLIB_Z_BUF_ERROR')

     Message: ZLIB: Not enough room in the output buffer (probably,
     length of uncompressed data was corrupted)

   * Error: `1259' SQLSTATE: `HY000' (`ER_ZLIB_Z_DATA_ERROR')

     Message: ZLIB: Input data corrupted

   * Error: `1260' SQLSTATE: `HY000' (`ER_CUT_VALUE_GROUP_CONCAT')

     Message: Row %u was cut by GROUP_CONCAT()

   * Error: `1261' SQLSTATE: `01000' (`ER_WARN_TOO_FEW_RECORDS')

     Message: Row %ld doesn't contain data for all columns

   * Error: `1262' SQLSTATE: `01000' (`ER_WARN_TOO_MANY_RECORDS')

     Message: Row %ld was truncated; it contained more data than there
     were input columns

   * Error: `1263' SQLSTATE: `22004' (`ER_WARN_NULL_TO_NOTNULL')

     Message: Column set to default value; NULL supplied to NOT NULL
     column '%s' at row %ld

   * Error: `1264' SQLSTATE: `22003' (`ER_WARN_DATA_OUT_OF_RANGE')

     Message: Out of range value for column '%s' at row %ld

   * Error: `1265' SQLSTATE: `01000' (`WARN_DATA_TRUNCATED')

     Message: Data truncated for column '%s' at row %ld

   * Error: `1266' SQLSTATE: `HY000' (`ER_WARN_USING_OTHER_HANDLER')

     Message: Using storage engine %s for table '%s'

   * Error: `1267' SQLSTATE: `HY000' (`ER_CANT_AGGREGATE_2COLLATIONS')

     Message: Illegal mix of collations (%s,%s) and (%s,%s) for
     operation '%s'

   * Error: `1268' SQLSTATE: `HY000' (`ER_DROP_USER')

     Message: Cannot drop one or more of the requested users

   * Error: `1269' SQLSTATE: `HY000' (`ER_REVOKE_GRANTS')

     Message: Can't revoke all privileges for one or more of the
     requested users

   * Error: `1270' SQLSTATE: `HY000' (`ER_CANT_AGGREGATE_3COLLATIONS')

     Message: Illegal mix of collations (%s,%s), (%s,%s), (%s,%s) for
     operation '%s'

   * Error: `1271' SQLSTATE: `HY000' (`ER_CANT_AGGREGATE_NCOLLATIONS')

     Message: Illegal mix of collations for operation '%s'

   * Error: `1272' SQLSTATE: `HY000' (`ER_VARIABLE_IS_NOT_STRUCT')

     Message: Variable '%s' is not a variable component (can't be used
     as XXXX.variable_name)

   * Error: `1273' SQLSTATE: `HY000' (`ER_UNKNOWN_COLLATION')

     Message: Unknown collation: '%s'

   * Error: `1274' SQLSTATE: `HY000' (`ER_SLAVE_IGNORED_SSL_PARAMS')

     Message: SSL parameters in CHANGE MASTER are ignored because this
     MySQL slave was compiled without SSL support; they can be used
     later if MySQL slave with SSL is started

   * Error: `1275' SQLSTATE: `HY000'
     (`ER_SERVER_IS_IN_SECURE_AUTH_MODE')

     Message: Server is running in -secure-auth mode, but '%s'@'%s' has
     a password in the old format; please change the password to the
     new format

   * Error: `1276' SQLSTATE: `HY000' (`ER_WARN_FIELD_RESOLVED')

     Message: Field or reference '%s%s%s%s%s' of SELECT #%d was
     resolved in SELECT #%d

   * Error: `1277' SQLSTATE: `HY000' (`ER_BAD_SLAVE_UNTIL_COND')

     Message: Incorrect parameter or combination of parameters for
     START SLAVE UNTIL

   * Error: `1278' SQLSTATE: `HY000' (`ER_MISSING_SKIP_SLAVE')

     Message: It is recommended to use -skip-slave-start when doing
     step-by-step replication with START SLAVE UNTIL; otherwise, you
     will get problems if you get an unexpected slave's mysqld restart

   * Error: `1279' SQLSTATE: `HY000' (`ER_UNTIL_COND_IGNORED')

     Message: SQL thread is not to be started so UNTIL options are
     ignored

   * Error: `1280' SQLSTATE: `42000' (`ER_WRONG_NAME_FOR_INDEX')

     Message: Incorrect index name '%s'

   * Error: `1281' SQLSTATE: `42000' (`ER_WRONG_NAME_FOR_CATALOG')

     Message: Incorrect catalog name '%s'

   * Error: `1282' SQLSTATE: `HY000' (`ER_WARN_QC_RESIZE')

     Message: Query cache failed to set size %lu; new query cache size
     is %lu

   * Error: `1283' SQLSTATE: `HY000' (`ER_BAD_FT_COLUMN')

     Message: Column '%s' cannot be part of FULLTEXT index

   * Error: `1284' SQLSTATE: `HY000' (`ER_UNKNOWN_KEY_CACHE')

     Message: Unknown key cache '%s'

   * Error: `1285' SQLSTATE: `HY000' (`ER_WARN_HOSTNAME_WONT_WORK')

     Message: MySQL is started in -skip-name-resolve mode; you must
     restart it without this switch for this grant to work

   * Error: `1286' SQLSTATE: `42000' (`ER_UNKNOWN_STORAGE_ENGINE')

     Message: Unknown storage engine '%s'

   * Error: `1287' SQLSTATE: `HY000' (`ER_WARN_DEPRECATED_SYNTAX')

     Message: '%s' is deprecated; use '%s' instead

   * Error: `1288' SQLSTATE: `HY000' (`ER_NON_UPDATABLE_TABLE')

     Message: The target table %s of the %s is not updatable

   * Error: `1289' SQLSTATE: `HY000' (`ER_FEATURE_DISABLED')

     Message: The '%s' feature is disabled; you need MySQL built with
     '%s' to have it working

   * Error: `1290' SQLSTATE: `HY000' (`ER_OPTION_PREVENTS_STATEMENT')

     Message: The MySQL server is running with the %s option so it
     cannot execute this statement

   * Error: `1291' SQLSTATE: `HY000' (`ER_DUPLICATED_VALUE_IN_TYPE')

     Message: Column '%s' has duplicated value '%s' in %s

   * Error: `1292' SQLSTATE: `22007' (`ER_TRUNCATED_WRONG_VALUE')

     Message: Truncated incorrect %s value: '%s'

   * Error: `1293' SQLSTATE: `HY000' (`ER_TOO_MUCH_AUTO_TIMESTAMP_COLS')

     Message: Incorrect table definition; there can be only one
     TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE
     clause

   * Error: `1294' SQLSTATE: `HY000' (`ER_INVALID_ON_UPDATE')

     Message: Invalid ON UPDATE clause for '%s' column

   * Error: `1295' SQLSTATE: `HY000' (`ER_UNSUPPORTED_PS')

     Message: This command is not supported in the prepared statement
     protocol yet

   * Error: `1296' SQLSTATE: `HY000' (`ER_GET_ERRMSG')

     Message: Got error %d '%s' from %s

   * Error: `1297' SQLSTATE: `HY000' (`ER_GET_TEMPORARY_ERRMSG')

     Message: Got temporary error %d '%s' from %s

   * Error: `1298' SQLSTATE: `HY000' (`ER_UNKNOWN_TIME_ZONE')

     Message: Unknown or incorrect time zone: '%s'

   * Error: `1299' SQLSTATE: `HY000' (`ER_WARN_INVALID_TIMESTAMP')

     Message: Invalid TIMESTAMP value in column '%s' at row %ld

   * Error: `1300' SQLSTATE: `HY000' (`ER_INVALID_CHARACTER_STRING')

     Message: Invalid %s character string: '%s'

   * Error: `1301' SQLSTATE: `HY000'
     (`ER_WARN_ALLOWED_PACKET_OVERFLOWED')

     Message: Result of %s() was larger than max_allowed_packet (%ld) -
     truncated

   * Error: `1302' SQLSTATE: `HY000' (`ER_CONFLICTING_DECLARATIONS')

     Message: Conflicting declarations: '%s%s' and '%s%s'

   * Error: `1303' SQLSTATE: `2F003' (`ER_SP_NO_RECURSIVE_CREATE')

     Message: Can't create a %s from within another stored routine

   * Error: `1304' SQLSTATE: `42000' (`ER_SP_ALREADY_EXISTS')

     Message: %s %s already exists

   * Error: `1305' SQLSTATE: `42000' (`ER_SP_DOES_NOT_EXIST')

     Message: %s %s does not exist

   * Error: `1306' SQLSTATE: `HY000' (`ER_SP_DROP_FAILED')

     Message: Failed to DROP %s %s

   * Error: `1307' SQLSTATE: `HY000' (`ER_SP_STORE_FAILED')

     Message: Failed to CREATE %s %s

   * Error: `1308' SQLSTATE: `42000' (`ER_SP_LILABEL_MISMATCH')

     Message: %s with no matching label: %s

   * Error: `1309' SQLSTATE: `42000' (`ER_SP_LABEL_REDEFINE')

     Message: Redefining label %s

   * Error: `1310' SQLSTATE: `42000' (`ER_SP_LABEL_MISMATCH')

     Message: End-label %s without match

   * Error: `1311' SQLSTATE: `01000' (`ER_SP_UNINIT_VAR')

     Message: Referring to uninitialized variable %s

   * Error: `1312' SQLSTATE: `0A000' (`ER_SP_BADSELECT')

     Message: PROCEDURE %s can't return a result set in the given
     context

   * Error: `1313' SQLSTATE: `42000' (`ER_SP_BADRETURN')

     Message: RETURN is only allowed in a FUNCTION

   * Error: `1314' SQLSTATE: `0A000' (`ER_SP_BADSTATEMENT')

     Message: %s is not allowed in stored procedures

   * Error: `1315' SQLSTATE: `42000'
     (`ER_UPDATE_LOG_DEPRECATED_IGNORED')

     Message: The update log is deprecated and replaced by the binary
     log; SET SQL_LOG_UPDATE has been ignored

   * Error: `1316' SQLSTATE: `42000'
     (`ER_UPDATE_LOG_DEPRECATED_TRANSLATED')

     Message: The update log is deprecated and replaced by the binary
     log; SET SQL_LOG_UPDATE has been translated to SET SQL_LOG_BIN

   * Error: `1317' SQLSTATE: `70100' (`ER_QUERY_INTERRUPTED')

     Message: Query execution was interrupted

   * Error: `1318' SQLSTATE: `42000' (`ER_SP_WRONG_NO_OF_ARGS')

     Message: Incorrect number of arguments for %s %s; expected %u, got
     %u

   * Error: `1319' SQLSTATE: `42000' (`ER_SP_COND_MISMATCH')

     Message: Undefined CONDITION: %s

   * Error: `1320' SQLSTATE: `42000' (`ER_SP_NORETURN')

     Message: No RETURN found in FUNCTION %s

   * Error: `1321' SQLSTATE: `2F005' (`ER_SP_NORETURNEND')

     Message: FUNCTION %s ended without RETURN

   * Error: `1322' SQLSTATE: `42000' (`ER_SP_BAD_CURSOR_QUERY')

     Message: Cursor statement must be a SELECT

   * Error: `1323' SQLSTATE: `42000' (`ER_SP_BAD_CURSOR_SELECT')

     Message: Cursor SELECT must not have INTO

   * Error: `1324' SQLSTATE: `42000' (`ER_SP_CURSOR_MISMATCH')

     Message: Undefined CURSOR: %s

   * Error: `1325' SQLSTATE: `24000' (`ER_SP_CURSOR_ALREADY_OPEN')

     Message: Cursor is already open

   * Error: `1326' SQLSTATE: `24000' (`ER_SP_CURSOR_NOT_OPEN')

     Message: Cursor is not open

   * Error: `1327' SQLSTATE: `42000' (`ER_SP_UNDECLARED_VAR')

     Message: Undeclared variable: %s

   * Error: `1328' SQLSTATE: `HY000' (`ER_SP_WRONG_NO_OF_FETCH_ARGS')

     Message: Incorrect number of FETCH variables

   * Error: `1329' SQLSTATE: `02000' (`ER_SP_FETCH_NO_DATA')

     Message: No data - zero rows fetched, selected, or processed

   * Error: `1330' SQLSTATE: `42000' (`ER_SP_DUP_PARAM')

     Message: Duplicate parameter: %s

   * Error: `1331' SQLSTATE: `42000' (`ER_SP_DUP_VAR')

     Message: Duplicate variable: %s

   * Error: `1332' SQLSTATE: `42000' (`ER_SP_DUP_COND')

     Message: Duplicate condition: %s

   * Error: `1333' SQLSTATE: `42000' (`ER_SP_DUP_CURS')

     Message: Duplicate cursor: %s

   * Error: `1334' SQLSTATE: `HY000' (`ER_SP_CANT_ALTER')

     Message: Failed to ALTER %s %s

   * Error: `1335' SQLSTATE: `0A000' (`ER_SP_SUBSELECT_NYI')

     Message: Subquery value not supported

   * Error: `1336' SQLSTATE: `0A000'
     (`ER_STMT_NOT_ALLOWED_IN_SF_OR_TRG')

     Message: %s is not allowed in stored function or trigger

   * Error: `1337' SQLSTATE: `42000' (`ER_SP_VARCOND_AFTER_CURSHNDLR')

     Message: Variable or condition declaration after cursor or handler
     declaration

   * Error: `1338' SQLSTATE: `42000' (`ER_SP_CURSOR_AFTER_HANDLER')

     Message: Cursor declaration after handler declaration

   * Error: `1339' SQLSTATE: `20000' (`ER_SP_CASE_NOT_FOUND')

     Message: Case not found for CASE statement

   * Error: `1340' SQLSTATE: `HY000' (`ER_FPARSER_TOO_BIG_FILE')

     Message: Configuration file '%s' is too big

   * Error: `1341' SQLSTATE: `HY000' (`ER_FPARSER_BAD_HEADER')

     Message: Malformed file type header in file '%s'

   * Error: `1342' SQLSTATE: `HY000' (`ER_FPARSER_EOF_IN_COMMENT')

     Message: Unexpected end of file while parsing comment '%s'

   * Error: `1343' SQLSTATE: `HY000' (`ER_FPARSER_ERROR_IN_PARAMETER')

     Message: Error while parsing parameter '%s' (line: '%s')

   * Error: `1344' SQLSTATE: `HY000'
     (`ER_FPARSER_EOF_IN_UNKNOWN_PARAMETER')

     Message: Unexpected end of file while skipping unknown parameter
     '%s'

   * Error: `1345' SQLSTATE: `HY000' (`ER_VIEW_NO_EXPLAIN')

     Message: EXPLAIN/SHOW can not be issued; lacking privileges for
     underlying table

   * Error: `1346' SQLSTATE: `HY000' (`ER_FRM_UNKNOWN_TYPE')

     Message: File '%s' has unknown type '%s' in its header

   * Error: `1347' SQLSTATE: `HY000' (`ER_WRONG_OBJECT')

     Message: '%s.%s' is not %s

   * Error: `1348' SQLSTATE: `HY000' (`ER_NONUPDATEABLE_COLUMN')

     Message: Column '%s' is not updatable

   * Error: `1349' SQLSTATE: `HY000' (`ER_VIEW_SELECT_DERIVED')

     Message: View's SELECT contains a subquery in the FROM clause

   * Error: `1350' SQLSTATE: `HY000' (`ER_VIEW_SELECT_CLAUSE')

     Message: View's SELECT contains a '%s' clause

   * Error: `1351' SQLSTATE: `HY000' (`ER_VIEW_SELECT_VARIABLE')

     Message: View's SELECT contains a variable or parameter

   * Error: `1352' SQLSTATE: `HY000' (`ER_VIEW_SELECT_TMPTABLE')

     Message: View's SELECT refers to a temporary table '%s'

   * Error: `1353' SQLSTATE: `HY000' (`ER_VIEW_WRONG_LIST')

     Message: View's SELECT and view's field list have different column
     counts

   * Error: `1354' SQLSTATE: `HY000' (`ER_WARN_VIEW_MERGE')

     Message: View merge algorithm can't be used here for now (assumed
     undefined algorithm)

   * Error: `1355' SQLSTATE: `HY000' (`ER_WARN_VIEW_WITHOUT_KEY')

     Message: View being updated does not have complete key of
     underlying table in it

   * Error: `1356' SQLSTATE: `HY000' (`ER_VIEW_INVALID')

     Message: View '%s.%s' references invalid table(s) or column(s) or
     function(s) or definer/invoker of view lack rights to use them

   * Error: `1357' SQLSTATE: `HY000' (`ER_SP_NO_DROP_SP')

     Message: Can't drop or alter a %s from within another stored
     routine

   * Error: `1358' SQLSTATE: `HY000' (`ER_SP_GOTO_IN_HNDLR')

     Message: GOTO is not allowed in a stored procedure handler

   * Error: `1359' SQLSTATE: `HY000' (`ER_TRG_ALREADY_EXISTS')

     Message: Trigger already exists

   * Error: `1360' SQLSTATE: `HY000' (`ER_TRG_DOES_NOT_EXIST')

     Message: Trigger does not exist

   * Error: `1361' SQLSTATE: `HY000' (`ER_TRG_ON_VIEW_OR_TEMP_TABLE')

     Message: Trigger's '%s' is view or temporary table

   * Error: `1362' SQLSTATE: `HY000' (`ER_TRG_CANT_CHANGE_ROW')

     Message: Updating of %s row is not allowed in %strigger

   * Error: `1363' SQLSTATE: `HY000' (`ER_TRG_NO_SUCH_ROW_IN_TRG')

     Message: There is no %s row in %s trigger

   * Error: `1364' SQLSTATE: `HY000' (`ER_NO_DEFAULT_FOR_FIELD')

     Message: Field '%s' doesn't have a default value

   * Error: `1365' SQLSTATE: `22012' (`ER_DIVISION_BY_ZERO')

     Message: Division by 0

   * Error: `1366' SQLSTATE: `HY000'
     (`ER_TRUNCATED_WRONG_VALUE_FOR_FIELD')

     Message: Incorrect %s value: '%s' for column '%s' at row %ld

   * Error: `1367' SQLSTATE: `22007' (`ER_ILLEGAL_VALUE_FOR_TYPE')

     Message: Illegal %s '%s' value found during parsing

   * Error: `1368' SQLSTATE: `HY000' (`ER_VIEW_NONUPD_CHECK')

     Message: CHECK OPTION on non-updatable view '%s.%s'

   * Error: `1369' SQLSTATE: `HY000' (`ER_VIEW_CHECK_FAILED')

     Message: CHECK OPTION failed '%s.%s'

   * Error: `1370' SQLSTATE: `42000' (`ER_PROCACCESS_DENIED_ERROR')

     Message: %s command denied to user '%s'@'%s' for routine '%s'

   * Error: `1371' SQLSTATE: `HY000' (`ER_RELAY_LOG_FAIL')

     Message: Failed purging old relay logs: %s

   * Error: `1372' SQLSTATE: `HY000' (`ER_PASSWD_LENGTH')

     Message: Password hash should be a %d-digit hexadecimal number

   * Error: `1373' SQLSTATE: `HY000' (`ER_UNKNOWN_TARGET_BINLOG')

     Message: Target log not found in binlog index

   * Error: `1374' SQLSTATE: `HY000' (`ER_IO_ERR_LOG_INDEX_READ')

     Message: I/O error reading log index file

   * Error: `1375' SQLSTATE: `HY000' (`ER_BINLOG_PURGE_PROHIBITED')

     Message: Server configuration does not permit binlog purge

   * Error: `1376' SQLSTATE: `HY000' (`ER_FSEEK_FAIL')

     Message: Failed on fseek()

   * Error: `1377' SQLSTATE: `HY000' (`ER_BINLOG_PURGE_FATAL_ERR')

     Message: Fatal error during log purge

   * Error: `1378' SQLSTATE: `HY000' (`ER_LOG_IN_USE')

     Message: A purgeable log is in use, will not purge

   * Error: `1379' SQLSTATE: `HY000' (`ER_LOG_PURGE_UNKNOWN_ERR')

     Message: Unknown error during log purge

   * Error: `1380' SQLSTATE: `HY000' (`ER_RELAY_LOG_INIT')

     Message: Failed initializing relay log position: %s

   * Error: `1381' SQLSTATE: `HY000' (`ER_NO_BINARY_LOGGING')

     Message: You are not using binary logging

   * Error: `1382' SQLSTATE: `HY000' (`ER_RESERVED_SYNTAX')

     Message: The '%s' syntax is reserved for purposes internal to the
     MySQL server

   * Error: `1383' SQLSTATE: `HY000' (`ER_WSAS_FAILED')

     Message: WSAStartup Failed

   * Error: `1384' SQLSTATE: `HY000' (`ER_DIFF_GROUPS_PROC')

     Message: Can't handle procedures with different groups yet

   * Error: `1385' SQLSTATE: `HY000' (`ER_NO_GROUP_FOR_PROC')

     Message: Select must have a group with this procedure

   * Error: `1386' SQLSTATE: `HY000' (`ER_ORDER_WITH_PROC')

     Message: Can't use ORDER clause with this procedure

   * Error: `1387' SQLSTATE: `HY000' (`ER_LOGGING_PROHIBIT_CHANGING_OF')

     Message: Binary logging and replication forbid changing the global
     server %s

   * Error: `1388' SQLSTATE: `HY000' (`ER_NO_FILE_MAPPING')

     Message: Can't map file: %s, errno: %d

   * Error: `1389' SQLSTATE: `HY000' (`ER_WRONG_MAGIC')

     Message: Wrong magic in %s

   * Error: `1390' SQLSTATE: `HY000' (`ER_PS_MANY_PARAM')

     Message: Prepared statement contains too many placeholders

   * Error: `1391' SQLSTATE: `HY000' (`ER_KEY_PART_0')

     Message: Key part '%s' length cannot be 0

   * Error: `1392' SQLSTATE: `HY000' (`ER_VIEW_CHECKSUM')

     Message: View text checksum failed

   * Error: `1393' SQLSTATE: `HY000' (`ER_VIEW_MULTIUPDATE')

     Message: Can not modify more than one base table through a join
     view '%s.%s'

   * Error: `1394' SQLSTATE: `HY000' (`ER_VIEW_NO_INSERT_FIELD_LIST')

     Message: Can not insert into join view '%s.%s' without fields list

   * Error: `1395' SQLSTATE: `HY000' (`ER_VIEW_DELETE_MERGE_VIEW')

     Message: Can not delete from join view '%s.%s'

   * Error: `1396' SQLSTATE: `HY000' (`ER_CANNOT_USER')

     Message: Operation %s failed for %s

   * Error: `1397' SQLSTATE: `XAE04' (`ER_XAER_NOTA')

     Message: XAER_NOTA: Unknown XID

   * Error: `1398' SQLSTATE: `XAE05' (`ER_XAER_INVAL')

     Message: XAER_INVAL: Invalid arguments (or unsupported command)

   * Error: `1399' SQLSTATE: `XAE07' (`ER_XAER_RMFAIL')

     Message: XAER_RMFAIL: The command cannot be executed when global
     transaction is in the %s state

   * Error: `1400' SQLSTATE: `XAE09' (`ER_XAER_OUTSIDE')

     Message: XAER_OUTSIDE: Some work is done outside global transaction

   * Error: `1401' SQLSTATE: `XAE03' (`ER_XAER_RMERR')

     Message: XAER_RMERR: Fatal error occurred in the transaction
     branch - check your data for consistency

   * Error: `1402' SQLSTATE: `XA100' (`ER_XA_RBROLLBACK')

     Message: XA_RBROLLBACK: Transaction branch was rolled back

   * Error: `1403' SQLSTATE: `42000' (`ER_NONEXISTING_PROC_GRANT')

     Message: There is no such grant defined for user '%s' on host '%s'
     on routine '%s'

   * Error: `1404' SQLSTATE: `HY000' (`ER_PROC_AUTO_GRANT_FAIL')

     Message: Failed to grant EXECUTE and ALTER ROUTINE privileges

   * Error: `1405' SQLSTATE: `HY000' (`ER_PROC_AUTO_REVOKE_FAIL')

     Message: Failed to revoke all privileges to dropped routine

   * Error: `1406' SQLSTATE: `22001' (`ER_DATA_TOO_LONG')

     Message: Data too long for column '%s' at row %ld

   * Error: `1407' SQLSTATE: `42000' (`ER_SP_BAD_SQLSTATE')

     Message: Bad SQLSTATE: '%s'

   * Error: `1408' SQLSTATE: `HY000' (`ER_STARTUP')

     Message: %s: ready for connections. Version: '%s' socket: '%s'
     port: %d %s

   * Error: `1409' SQLSTATE: `HY000'
     (`ER_LOAD_FROM_FIXED_SIZE_ROWS_TO_VAR')

     Message: Can't load value from file with fixed size rows to
     variable

   * Error: `1410' SQLSTATE: `42000' (`ER_CANT_CREATE_USER_WITH_GRANT')

     Message: You are not allowed to create a user with GRANT

   * Error: `1411' SQLSTATE: `HY000' (`ER_WRONG_VALUE_FOR_TYPE')

     Message: Incorrect %s value: '%s' for function %s

   * Error: `1412' SQLSTATE: `HY000' (`ER_TABLE_DEF_CHANGED')

     Message: Table definition has changed, please retry transaction

   * Error: `1413' SQLSTATE: `42000' (`ER_SP_DUP_HANDLER')

     Message: Duplicate handler declared in the same block

   * Error: `1414' SQLSTATE: `42000' (`ER_SP_NOT_VAR_ARG')

     Message: OUT or INOUT argument %d for routine %s is not a variable
     or NEW pseudo-variable in BEFORE trigger

   * Error: `1415' SQLSTATE: `0A000' (`ER_SP_NO_RETSET')

     Message: Not allowed to return a result set from a %s

   * Error: `1416' SQLSTATE: `22003' (`ER_CANT_CREATE_GEOMETRY_OBJECT')

     Message: Cannot get geometry object from data you send to the
     GEOMETRY field

   * Error: `1417' SQLSTATE: `HY000' (`ER_FAILED_ROUTINE_BREAK_BINLOG')

     Message: A routine failed and has neither NO SQL nor READS SQL
     DATA in its declaration and binary logging is enabled; if
     non-transactional tables were updated, the binary log will miss
     their changes

   * Error: `1418' SQLSTATE: `HY000' (`ER_BINLOG_UNSAFE_ROUTINE')

     Message: This function has none of DETERMINISTIC, NO SQL, or READS
     SQL DATA in its declaration and binary logging is enabled (you
     *might* want to use the less safe log_bin_trust_function_creators
     variable)

   * Error: `1419' SQLSTATE: `HY000'
     (`ER_BINLOG_CREATE_ROUTINE_NEED_SUPER')

     Message: You do not have the SUPER privilege and binary logging is
     enabled (you *might* want to use the less safe
     log_bin_trust_function_creators variable)

   * Error: `1420' SQLSTATE: `HY000' (`ER_EXEC_STMT_WITH_OPEN_CURSOR')

     Message: You can't execute a prepared statement which has an open
     cursor associated with it. Reset the statement to re-execute it.

   * Error: `1421' SQLSTATE: `HY000' (`ER_STMT_HAS_NO_OPEN_CURSOR')

     Message: The statement (%lu) has no open cursor.

   * Error: `1422' SQLSTATE: `HY000'
     (`ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG')

     Message: Explicit or implicit commit is not allowed in stored
     function or trigger.

   * Error: `1423' SQLSTATE: `HY000' (`ER_NO_DEFAULT_FOR_VIEW_FIELD')

     Message: Field of view '%s.%s' underlying table doesn't have a
     default value

   * Error: `1424' SQLSTATE: `HY000' (`ER_SP_NO_RECURSION')

     Message: Recursive stored functions and triggers are not allowed.

   * Error: `1425' SQLSTATE: `42000' (`ER_TOO_BIG_SCALE')

     Message: Too big scale %d specified for column '%s'. Maximum is
     %lu.

   * Error: `1426' SQLSTATE: `42000' (`ER_TOO_BIG_PRECISION')

     Message: Too big precision %d specified for column '%s'. Maximum
     is %lu.

   * Error: `1427' SQLSTATE: `42000' (`ER_M_BIGGER_THAN_D')

     Message: For float(M,D), double(M,D) or decimal(M,D), M must be >=
     D (column '%s').

   * Error: `1428' SQLSTATE: `HY000' (`ER_WRONG_LOCK_OF_SYSTEM_TABLE')

     Message: You can't combine write-locking of system tables with
     other tables or lock types

   * Error: `1429' SQLSTATE: `HY000'
     (`ER_CONNECT_TO_FOREIGN_DATA_SOURCE')

     Message: Unable to connect to foreign data source: %s

   * Error: `1430' SQLSTATE: `HY000' (`ER_QUERY_ON_FOREIGN_DATA_SOURCE')

     Message: There was a problem processing the query on the foreign
     data source. Data source error: %s

   * Error: `1431' SQLSTATE: `HY000'
     (`ER_FOREIGN_DATA_SOURCE_DOESNT_EXIST')

     Message: The foreign data source you are trying to reference does
     not exist. Data source error: %s

   * Error: `1432' SQLSTATE: `HY000'
     (`ER_FOREIGN_DATA_STRING_INVALID_CANT_CREATE')

     Message: Can't create federated table. The data source connection
     string '%s' is not in the correct format

   * Error: `1433' SQLSTATE: `HY000' (`ER_FOREIGN_DATA_STRING_INVALID')

     Message: The data source connection string '%s' is not in the
     correct format

   * Error: `1434' SQLSTATE: `HY000' (`ER_CANT_CREATE_FEDERATED_TABLE')

     Message: Can't create federated table. Foreign data src error: %s

   * Error: `1435' SQLSTATE: `HY000' (`ER_TRG_IN_WRONG_SCHEMA')

     Message: Trigger in wrong schema

   * Error: `1436' SQLSTATE: `HY000' (`ER_STACK_OVERRUN_NEED_MORE')

     Message: Thread stack overrun: %ld bytes used of a %ld byte stack,
     and %ld bytes needed. Use 'mysqld -O thread_stack=#' to specify a
     bigger stack.

   * Error: `1437' SQLSTATE: `42000' (`ER_TOO_LONG_BODY')

     Message: Routine body for '%s' is too long

   * Error: `1438' SQLSTATE: `HY000'
     (`ER_WARN_CANT_DROP_DEFAULT_KEYCACHE')

     Message: Cannot drop default keycache

   * Error: `1439' SQLSTATE: `42000' (`ER_TOO_BIG_DISPLAYWIDTH')

     Message: Display width out of range for column '%s' (max = %lu)

   * Error: `1440' SQLSTATE: `XAE08' (`ER_XAER_DUPID')

     Message: XAER_DUPID: The XID already exists

   * Error: `1441' SQLSTATE: `22008' (`ER_DATETIME_FUNCTION_OVERFLOW')

     Message: Datetime function: %s field overflow

   * Error: `1442' SQLSTATE: `HY000'
     (`ER_CANT_UPDATE_USED_TABLE_IN_SF_OR_TRG')

     Message: Can't update table '%s' in stored function/trigger
     because it is already used by statement which invoked this stored
     function/trigger.

   * Error: `1443' SQLSTATE: `HY000' (`ER_VIEW_PREVENT_UPDATE')

     Message: The definition of table '%s' prevents operation %s on
     table '%s'.

   * Error: `1444' SQLSTATE: `HY000' (`ER_PS_NO_RECURSION')

     Message: The prepared statement contains a stored routine call
     that refers to that same statement. It's not allowed to execute a
     prepared statement in such a recursive manner

   * Error: `1445' SQLSTATE: `HY000' (`ER_SP_CANT_SET_AUTOCOMMIT')

     Message: Not allowed to set autocommit from a stored function or
     trigger

   * Error: `1446' SQLSTATE: `HY000' (`ER_MALFORMED_DEFINER')

     Message: Definer is not fully qualified

   * Error: `1447' SQLSTATE: `HY000' (`ER_VIEW_FRM_NO_USER')

     Message: View '%s'.'%s' has no definer information (old table
     format). Current user is used as definer. Please recreate the view!

   * Error: `1448' SQLSTATE: `HY000' (`ER_VIEW_OTHER_USER')

     Message: You need the SUPER privilege for creation view with
     '%s'@'%s' definer

   * Error: `1449' SQLSTATE: `HY000' (`ER_NO_SUCH_USER')

     Message: The user specified as a definer ('%s'@'%s') does not exist

   * Error: `1450' SQLSTATE: `HY000' (`ER_FORBID_SCHEMA_CHANGE')

     Message: Changing schema from '%s' to '%s' is not allowed.

   * Error: `1451' SQLSTATE: `23000' (`ER_ROW_IS_REFERENCED_2')

     Message: Cannot delete or update a parent row: a foreign key
     constraint fails (%s)

   * Error: `1452' SQLSTATE: `23000' (`ER_NO_REFERENCED_ROW_2')

     Message: Cannot add or update a child row: a foreign key
     constraint fails (%s)

   * Error: `1453' SQLSTATE: `42000' (`ER_SP_BAD_VAR_SHADOW')

     Message: Variable '%s' must be quoted with `...`, or renamed

   * Error: `1454' SQLSTATE: `HY000' (`ER_TRG_NO_DEFINER')

     Message: No definer attribute for trigger '%s'.'%s'. The trigger
     will be activated under the authorization of the invoker, which
     may have insufficient privileges. Please recreate the trigger.

   * Error: `1455' SQLSTATE: `HY000' (`ER_OLD_FILE_FORMAT')

     Message: '%s' has an old format, you should re-create the '%s'
     object(s)

   * Error: `1456' SQLSTATE: `HY000' (`ER_SP_RECURSION_LIMIT')

     Message: Recursive limit %d (as set by the max_sp_recursion_depth
     variable) was exceeded for routine %s

   * Error: `1457' SQLSTATE: `HY000' (`ER_SP_PROC_TABLE_CORRUPT')

     Message: Failed to load routine %s. The table mysql.proc is
     missing, corrupt, or contains bad data (internal code %d)

   * Error: `1458' SQLSTATE: `42000' (`ER_SP_WRONG_NAME')

     Message: Incorrect routine name '%s'

   * Error: `1459' SQLSTATE: `HY000' (`ER_TABLE_NEEDS_UPGRADE')

     Message: Table upgrade required. Please do "REPAIR TABLE `%s`" to
     fix it!

   * Error: `1460' SQLSTATE: `42000' (`ER_SP_NO_AGGREGATE')

     Message: AGGREGATE is not supported for stored functions

   * Error: `1461' SQLSTATE: `42000'
     (`ER_MAX_PREPARED_STMT_COUNT_REACHED')

     Message: Can't create more than max_prepared_stmt_count statements
     (current value: %lu)

   * Error: `1462' SQLSTATE: `HY000' (`ER_VIEW_RECURSIVE')

     Message: `%s`.`%s` contains view recursion

   * Error: `1463' SQLSTATE: `42000' (`ER_NON_GROUPING_FIELD_USED')

     Message: non-grouping field '%s' is used in %s clause

   * Error: `1464' SQLSTATE: `HY000' (`ER_TABLE_CANT_HANDLE_SPKEYS')

     Message: The used table type doesn't support SPATIAL indexes

   * Error: `1465' SQLSTATE: `HY000' (`ER_NO_TRIGGERS_ON_SYSTEM_SCHEMA')

     Message: Triggers can not be created on system tables

   * Error: `1466' SQLSTATE: `HY000' (`ER_REMOVED_SPACES')

     Message: Leading spaces are removed from name '%s'

   * Error: `1467' SQLSTATE: `HY000' (`ER_AUTOINC_READ_FAILED')

     Message: Failed to read auto-increment value from storage engine

   * Error: `1468' SQLSTATE: `HY000' (`ER_USERNAME')

     Message: user name

   * Error: `1469' SQLSTATE: `HY000' (`ER_HOSTNAME')

     Message: host name

   * Error: `1470' SQLSTATE: `HY000' (`ER_WRONG_STRING_LENGTH')

     Message: String '%s' is too long for %s (should be no longer than
     %d)

   * Error: `1471' SQLSTATE: `HY000' (`ER_NON_INSERTABLE_TABLE')

     Message: The target table %s of the %s is not insertable-into

   * Error: `1472' SQLSTATE: `HY000' (`ER_ADMIN_WRONG_MRG_TABLE')

     Message: Table '%s' is differently defined or of non-MyISAM type
     or doesn't exist

   * Error: `1473' SQLSTATE: `HY000'
     (`ER_TOO_HIGH_LEVEL_OF_NESTING_FOR_SELECT')

     Message: Too high level of nesting for select

   * Error: `1474' SQLSTATE: `HY000' (`ER_NAME_BECOMES_EMPTY')

     Message: Name '%s' has become "

   * Error: `1475' SQLSTATE: `HY000' (`ER_AMBIGUOUS_FIELD_TERM')

     Message: First character of the FIELDS TERMINATED string is
     ambiguous; please use non-optional and non-empty FIELDS ENCLOSED BY

   * Error: `1476' SQLSTATE: `HY000' (`ER_FOREIGN_SERVER_EXISTS')

     Message: The foreign server, %s, you are trying to create already
     exists.

   * Error: `1477' SQLSTATE: `HY000' (`ER_FOREIGN_SERVER_DOESNT_EXIST')

     Message: The foreign server name you are trying to reference does
     not exist. Data source error: %s

   * Error: `1478' SQLSTATE: `HY000' (`ER_ILLEGAL_HA_CREATE_OPTION')

     Message: Table storage engine '%s' does not support the create
     option '%s'

   * Error: `1479' SQLSTATE: `HY000'
     (`ER_PARTITION_REQUIRES_VALUES_ERROR')

     Message: Syntax error: %s PARTITIONING requires definition of
     VALUES %s for each partition

   * Error: `1480' SQLSTATE: `HY000' (`ER_PARTITION_WRONG_VALUES_ERROR')

     Message: Only %s PARTITIONING can use VALUES %s in partition
     definition

   * Error: `1481' SQLSTATE: `HY000' (`ER_PARTITION_MAXVALUE_ERROR')

     Message: MAXVALUE can only be used in last partition definition

   * Error: `1482' SQLSTATE: `HY000' (`ER_PARTITION_SUBPARTITION_ERROR')

     Message: Subpartitions can only be hash partitions and by key

   * Error: `1483' SQLSTATE: `HY000' (`ER_PARTITION_SUBPART_MIX_ERROR')

     Message: Must define subpartitions on all partitions if on one
     partition

   * Error: `1484' SQLSTATE: `HY000'
     (`ER_PARTITION_WRONG_NO_PART_ERROR')

     Message: Wrong number of partitions defined, mismatch with
     previous setting

   * Error: `1485' SQLSTATE: `HY000'
     (`ER_PARTITION_WRONG_NO_SUBPART_ERROR')

     Message: Wrong number of subpartitions defined, mismatch with
     previous setting

   * Error: `1486' SQLSTATE: `HY000'
     (`ER_CONST_EXPR_IN_PARTITION_FUNC_ERROR')

     Message: Constant/Random expression in (sub)partitioning function
     is not allowed

   * Error: `1487' SQLSTATE: `HY000'
     (`ER_NO_CONST_EXPR_IN_RANGE_OR_LIST_ERROR')

     Message: Expression in RANGE/LIST VALUES must be constant

   * Error: `1488' SQLSTATE: `HY000' (`ER_FIELD_NOT_FOUND_PART_ERROR')

     Message: Field in list of fields for partition function not found
     in table

   * Error: `1489' SQLSTATE: `HY000'
     (`ER_LIST_OF_FIELDS_ONLY_IN_HASH_ERROR')

     Message: List of fields is only allowed in KEY partitions

   * Error: `1490' SQLSTATE: `HY000'
     (`ER_INCONSISTENT_PARTITION_INFO_ERROR')

     Message: The partition info in the frm file is not consistent with
     what can be written into the frm file

   * Error: `1491' SQLSTATE: `HY000'
     (`ER_PARTITION_FUNC_NOT_ALLOWED_ERROR')

     Message: The %s function returns the wrong type

   * Error: `1492' SQLSTATE: `HY000'
     (`ER_PARTITIONS_MUST_BE_DEFINED_ERROR')

     Message: For %s partitions each partition must be defined

   * Error: `1493' SQLSTATE: `HY000' (`ER_RANGE_NOT_INCREASING_ERROR')

     Message: VALUES LESS THAN value must be strictly increasing for
     each partition

   * Error: `1494' SQLSTATE: `HY000'
     (`ER_INCONSISTENT_TYPE_OF_FUNCTIONS_ERROR')

     Message: VALUES value must be of same type as partition function

   * Error: `1495' SQLSTATE: `HY000'
     (`ER_MULTIPLE_DEF_CONST_IN_LIST_PART_ERROR')

     Message: Multiple definition of same constant in list partitioning

   * Error: `1496' SQLSTATE: `HY000' (`ER_PARTITION_ENTRY_ERROR')

     Message: Partitioning can not be used stand-alone in query

   * Error: `1497' SQLSTATE: `HY000' (`ER_MIX_HANDLER_ERROR')

     Message: The mix of handlers in the partitions is not allowed in
     this version of MySQL

   * Error: `1498' SQLSTATE: `HY000' (`ER_PARTITION_NOT_DEFINED_ERROR')

     Message: For the partitioned engine it is necessary to define all
     %s

   * Error: `1499' SQLSTATE: `HY000' (`ER_TOO_MANY_PARTITIONS_ERROR')

     Message: Too many partitions (including subpartitions) were defined

   * Error: `1500' SQLSTATE: `HY000' (`ER_SUBPARTITION_ERROR')

     Message: It is only possible to mix RANGE/LIST partitioning with
     HASH/KEY partitioning for subpartitioning

   * Error: `1501' SQLSTATE: `HY000' (`ER_CANT_CREATE_HANDLER_FILE')

     Message: Failed to create specific handler file

   * Error: `1502' SQLSTATE: `HY000'
     (`ER_BLOB_FIELD_IN_PART_FUNC_ERROR')

     Message: A BLOB field is not allowed in partition function

   * Error: `1503' SQLSTATE: `HY000'
     (`ER_UNIQUE_KEY_NEED_ALL_FIELDS_IN_PF')

     Message: A %s must include all columns in the table's partitioning
     function

   * Error: `1504' SQLSTATE: `HY000' (`ER_NO_PARTS_ERROR')

     Message: Number of %s = 0 is not an allowed value

   * Error: `1505' SQLSTATE: `HY000'
     (`ER_PARTITION_MGMT_ON_NONPARTITIONED')

     Message: Partition management on a not partitioned table is not
     possible

   * Error: `1506' SQLSTATE: `HY000' (`ER_FOREIGN_KEY_ON_PARTITIONED')

     Message: Foreign key clause is not yet supported in conjunction
     with partitioning

   * Error: `1507' SQLSTATE: `HY000' (`ER_DROP_PARTITION_NON_EXISTENT')

     Message: Error in list of partitions to %s

   * Error: `1508' SQLSTATE: `HY000' (`ER_DROP_LAST_PARTITION')

     Message: Cannot remove all partitions, use DROP TABLE instead

   * Error: `1509' SQLSTATE: `HY000'
     (`ER_COALESCE_ONLY_ON_HASH_PARTITION')

     Message: COALESCE PARTITION can only be used on HASH/KEY partitions

   * Error: `1510' SQLSTATE: `HY000' (`ER_REORG_HASH_ONLY_ON_SAME_NO')

     Message: REORGANIZE PARTITION can only be used to reorganize
     partitions not to change their numbers

   * Error: `1511' SQLSTATE: `HY000' (`ER_REORG_NO_PARAM_ERROR')

     Message: REORGANIZE PARTITION without parameters can only be used
     on auto-partitioned tables using HASH PARTITIONs

   * Error: `1512' SQLSTATE: `HY000' (`ER_ONLY_ON_RANGE_LIST_PARTITION')

     Message: %s PARTITION can only be used on RANGE/LIST partitions

   * Error: `1513' SQLSTATE: `HY000' (`ER_ADD_PARTITION_SUBPART_ERROR')

     Message: Trying to Add partition(s) with wrong number of
     subpartitions

   * Error: `1514' SQLSTATE: `HY000'
     (`ER_ADD_PARTITION_NO_NEW_PARTITION')

     Message: At least one partition must be added

   * Error: `1515' SQLSTATE: `HY000'
     (`ER_COALESCE_PARTITION_NO_PARTITION')

     Message: At least one partition must be coalesced

   * Error: `1516' SQLSTATE: `HY000' (`ER_REORG_PARTITION_NOT_EXIST')

     Message: More partitions to reorganize than there are partitions

   * Error: `1517' SQLSTATE: `HY000' (`ER_SAME_NAME_PARTITION')

     Message: Duplicate partition name %s

   * Error: `1518' SQLSTATE: `HY000' (`ER_NO_BINLOG_ERROR')

     Message: It is not allowed to shut off binlog on this command

   * Error: `1519' SQLSTATE: `HY000' (`ER_CONSECUTIVE_REORG_PARTITIONS')

     Message: When reorganizing a set of partitions they must be in
     consecutive order

   * Error: `1520' SQLSTATE: `HY000' (`ER_REORG_OUTSIDE_RANGE')

     Message: Reorganize of range partitions cannot change total ranges
     except for last partition where it can extend the range

   * Error: `1521' SQLSTATE: `HY000' (`ER_PARTITION_FUNCTION_FAILURE')

     Message: Partition function not supported in this version for this
     handler

   * Error: `1522' SQLSTATE: `HY000' (`ER_PART_STATE_ERROR')

     Message: Partition state cannot be defined from CREATE/ALTER TABLE

   * Error: `1523' SQLSTATE: `HY000' (`ER_LIMITED_PART_RANGE')

     Message: The %s handler only supports 32 bit integers in VALUES

   * Error: `1524' SQLSTATE: `HY000' (`ER_PLUGIN_IS_NOT_LOADED')

     Message: Plugin '%s' is not loaded

   * Error: `1525' SQLSTATE: `HY000' (`ER_WRONG_VALUE')

     Message: Incorrect %s value: '%s'

   * Error: `1526' SQLSTATE: `HY000' (`ER_NO_PARTITION_FOR_GIVEN_VALUE')

     Message: Table has no partition for value %s

   * Error: `1527' SQLSTATE: `HY000' (`ER_FILEGROUP_OPTION_ONLY_ONCE')

     Message: It is not allowed to specify %s more than once

   * Error: `1528' SQLSTATE: `HY000' (`ER_CREATE_FILEGROUP_FAILED')

     Message: Failed to create %s

   * Error: `1529' SQLSTATE: `HY000' (`ER_DROP_FILEGROUP_FAILED')

     Message: Failed to drop %s

   * Error: `1530' SQLSTATE: `HY000' (`ER_TABLESPACE_AUTO_EXTEND_ERROR')

     Message: The handler doesn't support autoextend of tablespaces

   * Error: `1531' SQLSTATE: `HY000' (`ER_WRONG_SIZE_NUMBER')

     Message: A size parameter was incorrectly specified, either number
     or on the form 10M

   * Error: `1532' SQLSTATE: `HY000' (`ER_SIZE_OVERFLOW_ERROR')

     Message: The size number was correct but we don't allow the digit
     part to be more than 2 billion

   * Error: `1533' SQLSTATE: `HY000' (`ER_ALTER_FILEGROUP_FAILED')

     Message: Failed to alter: %s

   * Error: `1534' SQLSTATE: `HY000' (`ER_BINLOG_ROW_LOGGING_FAILED')

     Message: Writing one row to the row-based binary log failed

   * Error: `1535' SQLSTATE: `HY000' (`ER_BINLOG_ROW_WRONG_TABLE_DEF')

     Message: Table definition on master and slave does not match: %s

   * Error: `1536' SQLSTATE: `HY000' (`ER_BINLOG_ROW_RBR_TO_SBR')

     Message: Slave running with -log-slave-updates must use row-based
     binary logging to be able to replicate row-based binary log events

   * Error: `1537' SQLSTATE: `HY000' (`ER_EVENT_ALREADY_EXISTS')

     Message: Event '%s' already exists

   * Error: `1538' SQLSTATE: `HY000' (`ER_EVENT_STORE_FAILED')

     Message: Failed to store event %s. Error code %d from storage
     engine.

   * Error: `1539' SQLSTATE: `HY000' (`ER_EVENT_DOES_NOT_EXIST')

     Message: Unknown event '%s'

   * Error: `1540' SQLSTATE: `HY000' (`ER_EVENT_CANT_ALTER')

     Message: Failed to alter event '%s'

   * Error: `1541' SQLSTATE: `HY000' (`ER_EVENT_DROP_FAILED')

     Message: Failed to drop %s

   * Error: `1542' SQLSTATE: `HY000'
     (`ER_EVENT_INTERVAL_NOT_POSITIVE_OR_TOO_BIG')

     Message: INTERVAL is either not positive or too big

   * Error: `1543' SQLSTATE: `HY000' (`ER_EVENT_ENDS_BEFORE_STARTS')

     Message: ENDS is either invalid or before STARTS

   * Error: `1544' SQLSTATE: `HY000' (`ER_EVENT_EXEC_TIME_IN_THE_PAST')

     Message: Event execution time is in the past. Event has been
     disabled

   * Error: `1545' SQLSTATE: `HY000' (`ER_EVENT_OPEN_TABLE_FAILED')

     Message: Failed to open mysql.event

   * Error: `1546' SQLSTATE: `HY000'
     (`ER_EVENT_NEITHER_M_EXPR_NOR_M_AT')

     Message: No datetime expression provided

   * Error: `1547' SQLSTATE: `HY000'
     (`ER_COL_COUNT_DOESNT_MATCH_CORRUPTED')

     Message: Column count of mysql.%s is wrong. Expected %d, found %d.
     The table is probably corrupted

   * Error: `1548' SQLSTATE: `HY000' (`ER_CANNOT_LOAD_FROM_TABLE')

     Message: Cannot load from mysql.%s. The table is probably corrupted

   * Error: `1549' SQLSTATE: `HY000' (`ER_EVENT_CANNOT_DELETE')

     Message: Failed to delete the event from mysql.event

   * Error: `1550' SQLSTATE: `HY000' (`ER_EVENT_COMPILE_ERROR')

     Message: Error during compilation of event's body

   * Error: `1551' SQLSTATE: `HY000' (`ER_EVENT_SAME_NAME')

     Message: Same old and new event name

   * Error: `1552' SQLSTATE: `HY000' (`ER_EVENT_DATA_TOO_LONG')

     Message: Data for column '%s' too long

   * Error: `1553' SQLSTATE: `HY000' (`ER_DROP_INDEX_FK')

     Message: Cannot drop index '%s': needed in a foreign key constraint

   * Error: `1554' SQLSTATE: `HY000'
     (`ER_WARN_DEPRECATED_SYNTAX_WITH_VER')

     Message: The syntax '%s' is deprecated and will be removed in
     MySQL %s. Please use %s instead

   * Error: `1555' SQLSTATE: `HY000' (`ER_CANT_WRITE_LOCK_LOG_TABLE')

     Message: You can't write-lock a log table. Only read access is
     possible

   * Error: `1556' SQLSTATE: `HY000' (`ER_CANT_LOCK_LOG_TABLE')

     Message: You can't use locks with log tables.

   * Error: `1557' SQLSTATE: `23000' (`ER_FOREIGN_DUPLICATE_KEY')

     Message: Upholding foreign key constraints for table '%s', entry
     '%s', key %d would lead to a duplicate entry

   * Error: `1558' SQLSTATE: `HY000'
     (`ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE')

     Message: Column count of mysql.%s is wrong. Expected %d, found %d.
     Created with MySQL %d, now running %d. Please use mysql_upgrade to
     fix this error.

   * Error: `1559' SQLSTATE: `HY000'
     (`ER_TEMP_TABLE_PREVENTS_SWITCH_OUT_OF_RBR')

     Message: Cannot switch out of the row-based binary log format when
     the session has open temporary tables

   * Error: `1560' SQLSTATE: `HY000'
     (`ER_STORED_FUNCTION_PREVENTS_SWITCH_BINLOG_FORMAT')

     Message: Cannot change the binary logging format inside a stored
     function or trigger

   * Error: `1561' SQLSTATE: `HY000'
     (`ER_NDB_CANT_SWITCH_BINLOG_FORMAT')

     Message: The NDB cluster engine does not support changing the
     binlog format on the fly yet

   * Error: `1562' SQLSTATE: `HY000' (`ER_PARTITION_NO_TEMPORARY')

     Message: Cannot create temporary table with partitions

   * Error: `1563' SQLSTATE: `HY000' (`ER_PARTITION_CONST_DOMAIN_ERROR')

     Message: Partition constant is out of partition function domain

   * Error: `1564' SQLSTATE: `HY000'
     (`ER_PARTITION_FUNCTION_IS_NOT_ALLOWED')

     Message: This partition function is not allowed

   * Error: `1565' SQLSTATE: `HY000' (`ER_DDL_LOG_ERROR')

     Message: Error in DDL log

   * Error: `1566' SQLSTATE: `HY000' (`ER_NULL_IN_VALUES_LESS_THAN')

     Message: Not allowed to use NULL value in VALUES LESS THAN

   * Error: `1567' SQLSTATE: `HY000' (`ER_WRONG_PARTITION_NAME')

     Message: Incorrect partition name

   * Error: `1568' SQLSTATE: `25001' (`ER_CANT_CHANGE_TX_ISOLATION')

     Message: Transaction isolation level can't be changed while a
     transaction is in progress

   * Error: `1569' SQLSTATE: `HY000' (`ER_DUP_ENTRY_AUTOINCREMENT_CASE')

     Message: ALTER TABLE causes auto_increment resequencing, resulting
     in duplicate entry '%s' for key '%s'

   * Error: `1570' SQLSTATE: `HY000' (`ER_EVENT_MODIFY_QUEUE_ERROR')

     Message: Internal scheduler error %d

   * Error: `1571' SQLSTATE: `HY000' (`ER_EVENT_SET_VAR_ERROR')

     Message: Error during starting/stopping of the scheduler. Error
     code %u

   * Error: `1572' SQLSTATE: `HY000' (`ER_PARTITION_MERGE_ERROR')

     Message: Engine cannot be used in partitioned tables

   * Error: `1573' SQLSTATE: `HY000' (`ER_CANT_ACTIVATE_LOG')

     Message: Cannot activate '%s' log

   * Error: `1574' SQLSTATE: `HY000' (`ER_RBR_NOT_AVAILABLE')

     Message: The server was not built with row-based replication

   * Error: `1575' SQLSTATE: `HY000' (`ER_BASE64_DECODE_ERROR')

     Message: Decoding of base64 string failed

   * Error: `1576' SQLSTATE: `HY000' (`ER_EVENT_RECURSION_FORBIDDEN')

     Message: Recursion of EVENT DDL statements is forbidden when body
     is present

   * Error: `1577' SQLSTATE: `HY000' (`ER_EVENTS_DB_ERROR')

     Message: Cannot proceed because system tables used by Event
     Scheduler were found damaged at server start

   * Error: `1578' SQLSTATE: `HY000' (`ER_ONLY_INTEGERS_ALLOWED')

     Message: Only integers allowed as number here

   * Error: `1579' SQLSTATE: `HY000' (`ER_UNSUPORTED_LOG_ENGINE')

     Message: This storage engine cannot be used for log tables"

   * Error: `1580' SQLSTATE: `HY000' (`ER_BAD_LOG_STATEMENT')

     Message: You cannot '%s' a log table if logging is enabled

   * Error: `1581' SQLSTATE: `HY000' (`ER_CANT_RENAME_LOG_TABLE')

     Message: Cannot rename '%s'. When logging enabled, rename to/from
     log table must rename two tables: the log table to an archive
     table and another table back to '%s'

   * Error: `1582' SQLSTATE: `42000'
     (`ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT')

     Message: Incorrect parameter count in the call to native function
     '%s'

   * Error: `1583' SQLSTATE: `42000'
     (`ER_WRONG_PARAMETERS_TO_NATIVE_FCT')

     Message: Incorrect parameters in the call to native function '%s'

   * Error: `1584' SQLSTATE: `42000'
     (`ER_WRONG_PARAMETERS_TO_STORED_FCT')

     Message: Incorrect parameters in the call to stored function '%s'

   * Error: `1585' SQLSTATE: `HY000' (`ER_NATIVE_FCT_NAME_COLLISION')

     Message: This function '%s' has the same name as a native function

   * Error: `1586' SQLSTATE: `23000' (`ER_DUP_ENTRY_WITH_KEY_NAME')

     Message: Duplicate entry '%s' for key '%s'

   * Error: `1587' SQLSTATE: `HY000' (`ER_BINLOG_PURGE_EMFILE')

     Message: Too many files opened, please execute the command again

   * Error: `1588' SQLSTATE: `HY000'
     (`ER_EVENT_CANNOT_CREATE_IN_THE_PAST')

     Message: Event execution time is in the past and ON COMPLETION NOT
     PRESERVE is set. The event was dropped immediately after creation.

   * Error: `1589' SQLSTATE: `HY000'
     (`ER_EVENT_CANNOT_ALTER_IN_THE_PAST')

     Message: Event execution time is in the past and ON COMPLETION NOT
     PRESERVE is set. The event was dropped immediately after creation.

   * Error: `1590' SQLSTATE: `HY000' (`ER_SLAVE_INCIDENT')

     Message: The incident %s occured on the master. Message: %s

   * Error: `1591' SQLSTATE: `HY000'
     (`ER_NO_PARTITION_FOR_GIVEN_VALUE_SILENT')

     Message: Table has no partition for some existing values

   * Error: `1592' SQLSTATE: `HY000' (`ER_BINLOG_UNSAFE_STATEMENT')

     Message: Statement is not safe to log in statement format.

   * Error: `1593' SQLSTATE: `HY000' (`ER_SLAVE_FATAL_ERROR')

     Message: Fatal error: %s

   * Error: `1594' SQLSTATE: `HY000' (`ER_SLAVE_RELAY_LOG_READ_FAILURE')

     Message: Relay log read failure: %s

   * Error: `1595' SQLSTATE: `HY000'
     (`ER_SLAVE_RELAY_LOG_WRITE_FAILURE')

     Message: Relay log write failure: %s

   * Error: `1596' SQLSTATE: `HY000' (`ER_SLAVE_CREATE_EVENT_FAILURE')

     Message: Failed to create %s

   * Error: `1597' SQLSTATE: `HY000' (`ER_SLAVE_MASTER_COM_FAILURE')

     Message: Master command %s failed: %s

   * Error: `1598' SQLSTATE: `HY000' (`ER_BINLOG_LOGGING_IMPOSSIBLE')

     Message: Binary logging not possible. Message: %s

   * Error: `1599' SQLSTATE: `HY000' (`ER_VIEW_NO_CREATION_CTX')

     Message: View `%s`.`%s` has no creation context

   * Error: `1600' SQLSTATE: `HY000' (`ER_VIEW_INVALID_CREATION_CTX')

     Message: Creation context of view `%s`.`%s' is invalid

   * Error: `1601' SQLSTATE: `HY000' (`ER_SR_INVALID_CREATION_CTX')

     Message: Creation context of stored routine `%s`.`%s` is invalid

   * Error: `1602' SQLSTATE: `HY000' (`ER_TRG_CORRUPTED_FILE')

     Message: Corrupted TRG file for table `%s`.`%s`

   * Error: `1603' SQLSTATE: `HY000' (`ER_TRG_NO_CREATION_CTX')

     Message: Triggers for table `%s`.`%s` have no creation context

   * Error: `1604' SQLSTATE: `HY000' (`ER_TRG_INVALID_CREATION_CTX')

     Message: Trigger creation context of table `%s`.`%s` is invalid

   * Error: `1605' SQLSTATE: `HY000' (`ER_EVENT_INVALID_CREATION_CTX')

     Message: Creation context of event `%s`.`%s` is invalid

   * Error: `1606' SQLSTATE: `HY000' (`ER_TRG_CANT_OPEN_TABLE')

     Message: Cannot open table for trigger `%s`.`%s`

   * Error: `1607' SQLSTATE: `HY000' (`ER_CANT_CREATE_SROUTINE')

     Message: Cannot create stored routine `%s`. Check warnings

   * Error: `1608' SQLSTATE: `HY000' (`ER_SLAVE_AMBIGOUS_EXEC_MODE')

     Message: Ambiguous slave modes combination. %s

   * Error: `1609' SQLSTATE: `HY000'
     (`ER_NO_FORMAT_DESCRIPTION_EVENT_BEFORE_BINLOG_STATEMENT')

     Message: The BINLOG statement of type `%s` was not preceded by a
     format description BINLOG statement.

   * Error: `1610' SQLSTATE: `HY000' (`ER_SLAVE_CORRUPT_EVENT')

     Message: Corrupted replication event was detected

   * Error: `1611' SQLSTATE: `HY000' (`ER_LOAD_DATA_INVALID_COLUMN')

     Message: Invalid column reference (%s) in LOAD DATA

   * Error: `1612' SQLSTATE: `HY000' (`ER_LOG_PURGE_NO_FILE')

     Message: Being purged log %s was not found

   * Error: `1613' SQLSTATE: `XA106' (`ER_XA_RBTIMEOUT')

     Message: XA_RBTIMEOUT: Transaction branch was rolled back: took
     too long

   * Error: `1614' SQLSTATE: `XA102' (`ER_XA_RBDEADLOCK')

     Message: XA_RBDEADLOCK: Transaction branch was rolled back:
     deadlock was detected

   * Error: `1615' SQLSTATE: `HY000' (`ER_NEED_REPREPARE')

     Message: Prepared statement needs to be re-prepared

   * Error: `1616' SQLSTATE: `HY000' (`ER_DELAYED_NOT_SUPPORTED')

     Message: DELAYED option not supported for table '%s'

   * Error: `1617' SQLSTATE: `HY000' (`WARN_NO_MASTER_INFO')

     Message: The master info structure does not exist

   * Error: `1618' SQLSTATE: `HY000' (`WARN_OPTION_IGNORED')

     Message: <%s> option ignored

   * Error: `1619' SQLSTATE: `HY000' (`WARN_PLUGIN_DELETE_BUILTIN')

     Message: Built-in plugins cannot be deleted

   * Error: `1620' SQLSTATE: `HY000' (`WARN_PLUGIN_BUSY')

     Message: Plugin is busy and will be uninstalled on shutdown

   * Error: `1621' SQLSTATE: `HY000' (`ER_VARIABLE_IS_READONLY')

     Message: %s variable '%s' is read-only. Use SET %s to assign the
     value

   * Error: `1622' SQLSTATE: `HY000'
     (`ER_WARN_ENGINE_TRANSACTION_ROLLBACK')

     Message: Storage engine %s does not support rollback for this
     statement. Transaction rolled back and must be restarted

   * Error: `1623' SQLSTATE: `HY000' (`ER_SLAVE_HEARTBEAT_FAILURE')

     Message: Unexpected master's heartbeat data: %s

   * Error: `1624' SQLSTATE: `HY000'
     (`ER_SLAVE_HEARTBEAT_VALUE_OUT_OF_RANGE')

     Message: The requested value for the heartbeat period %s %s

   * Error: `1625' SQLSTATE: `HY000' (`ER_NDB_REPLICATION_SCHEMA_ERROR')

     Message: Bad schema for mysql.ndb_replication table. Message: %s

   * Error: `1626' SQLSTATE: `HY000' (`ER_CONFLICT_FN_PARSE_ERROR')

     Message: Error in parsing conflict function. Message: %s

   * Error: `1627' SQLSTATE: `HY000' (`ER_EXCEPTIONS_WRITE_ERROR')

     Message: Write to exceptions table failed. Message: %s"

   * Error: `1628' SQLSTATE: `HY000' (`ER_TOO_LONG_TABLE_COMMENT')

     Message: Comment for table '%s' is too long (max = %lu)

   * Error: `1629' SQLSTATE: `HY000' (`ER_TOO_LONG_FIELD_COMMENT')

     Message: Comment for field '%s' is too long (max = %lu)

   * Error: `1630' SQLSTATE: `HY000' (`ER_WARN_AUTO_CONVERT_LOCK')

     Message: Converted to non-transactional lock on '%s'

   * Error: `1631' SQLSTATE: `HY000' (`ER_NO_AUTO_CONVERT_LOCK_STRICT')

     Message: Cannot convert to non-transactional lock in strict mode
     on '%s'

   * Error: `1632' SQLSTATE: `HY000'
     (`ER_NO_AUTO_CONVERT_LOCK_TRANSACTION')

     Message: Cannot convert to non-transactional lock in an active
     transaction on '%s'

   * Error: `1633' SQLSTATE: `HY000' (`ER_NO_STORAGE_ENGINE')

     Message: Can't access storage engine of table %s

   * Error: `1634' SQLSTATE: `HY000' (`ER_BACKUP_BACKUP_START')

     Message: Starting backup process

   * Error: `1635' SQLSTATE: `HY000' (`ER_BACKUP_BACKUP_DONE')

     Message: Backup completed

   * Error: `1636' SQLSTATE: `HY000' (`ER_BACKUP_RESTORE_START')

     Message: Starting restore process

   * Error: `1637' SQLSTATE: `HY000' (`ER_BACKUP_RESTORE_DONE')

     Message: Restore completed

   * Error: `1638' SQLSTATE: `HY000' (`ER_BACKUP_NOTHING_TO_BACKUP')

     Message: Nothing to backup

   * Error: `1639' SQLSTATE: `HY000' (`ER_BACKUP_CANNOT_INCLUDE_DB')

     Message: Database '%s' cannot be included in a backup

   * Error: `1640' SQLSTATE: `HY000' (`ER_BACKUP_BACKUP')

     Message: Error during backup operation - see SHOW WARNINGS for
     more information

   * Error: `1641' SQLSTATE: `HY000' (`ER_BACKUP_RESTORE')

     Message: Error during restore operation - see SHOW WARNINGS for
     more information

   * Error: `1642' SQLSTATE: `HY000' (`ER_BACKUP_RUNNING')

     Message: Can't execute this command because another BACKUP/RESTORE
     operation is in progress

   * Error: `1643' SQLSTATE: `HY000' (`ER_BACKUP_BACKUP_PREPARE')

     Message: Error when preparing for backup operation

   * Error: `1644' SQLSTATE: `HY000' (`ER_BACKUP_RESTORE_PREPARE')

     Message: Error when preparing for restore operation

   * Error: `1645' SQLSTATE: `HY000' (`ER_BACKUP_INVALID_LOC')

     Message: Invalid backup location '%s'

   * Error: `1646' SQLSTATE: `HY000' (`ER_BACKUP_READ_LOC')

     Message: Can't read backup location '%s'

   * Error: `1647' SQLSTATE: `HY000' (`ER_BACKUP_WRITE_LOC')

     Message: Can't write to backup location '%s'

   * Error: `1648' SQLSTATE: `HY000' (`ER_BACKUP_LIST_DBS')

     Message: Can't enumerate server databases

   * Error: `1649' SQLSTATE: `HY000' (`ER_BACKUP_LIST_TABLES')

     Message: Can't enumerate server tables

   * Error: `1650' SQLSTATE: `HY000' (`ER_BACKUP_LIST_DB_TABLES')

     Message: Can't enumerate tables in database %s

   * Error: `1651' SQLSTATE: `HY000' (`ER_BACKUP_SKIP_VIEW')

     Message: Skipping view %s in database %s

   * Error: `1652' SQLSTATE: `HY000' (`ER_BACKUP_NO_ENGINE')

     Message: Skipping table %s since it has no valid storage engine

   * Error: `1653' SQLSTATE: `HY000' (`ER_BACKUP_TABLE_OPEN')

     Message: Can't open table %s

   * Error: `1654' SQLSTATE: `HY000' (`ER_BACKUP_READ_HEADER')

     Message: Can't read backup archive preamble

   * Error: `1655' SQLSTATE: `HY000' (`ER_BACKUP_WRITE_HEADER')

     Message: Can't write backup archive preamble

   * Error: `1656' SQLSTATE: `HY000' (`ER_BACKUP_NO_BACKUP_DRIVER')

     Message: Can't find backup driver for table %s

   * Error: `1657' SQLSTATE: `HY000' (`ER_BACKUP_NOT_ACCEPTED')

     Message: %s backup driver was selected for table %s but it rejects
     to handle this table

   * Error: `1658' SQLSTATE: `HY000' (`ER_BACKUP_CREATE_BACKUP_DRIVER')

     Message: Can't create %s backup driver

   * Error: `1659' SQLSTATE: `HY000' (`ER_BACKUP_CREATE_RESTORE_DRIVER')

     Message: Can't create %s restore driver

   * Error: `1660' SQLSTATE: `HY000' (`ER_BACKUP_TOO_MANY_IMAGES')

     Message: Backup image uses %d backup engines but maximum %d are
     supported

   * Error: `1661' SQLSTATE: `HY000' (`ER_BACKUP_WRITE_META')

     Message: Error when saving meta-data of %s

   * Error: `1662' SQLSTATE: `HY000' (`ER_BACKUP_READ_META')

     Message: Error when reading meta-data

   * Error: `1663' SQLSTATE: `HY000' (`ER_BACKUP_CREATE_META')

     Message: Failed to obtain meta-data for %s

   * Error: `1664' SQLSTATE: `HY000' (`ER_BACKUP_GET_BUF')

     Message: Can't allocate buffer for image data transfer

   * Error: `1665' SQLSTATE: `HY000' (`ER_BACKUP_WRITE_DATA')

     Message: Error when writing data from %s backup driver (data block
     for table #%d)

   * Error: `1666' SQLSTATE: `HY000' (`ER_BACKUP_READ_DATA')

     Message: Error when reading data from backup stream

   * Error: `1667' SQLSTATE: `HY000' (`ER_BACKUP_NEXT_CHUNK')

     Message: Can't go to the next chunk in backup stream

   * Error: `1668' SQLSTATE: `HY000' (`ER_BACKUP_INIT_BACKUP_DRIVER')

     Message: Can't initialize %s backup driver

   * Error: `1669' SQLSTATE: `HY000' (`ER_BACKUP_INIT_RESTORE_DRIVER')

     Message: Can't initialize %s restore driver

   * Error: `1670' SQLSTATE: `HY000' (`ER_BACKUP_STOP_BACKUP_DRIVER')

     Message: Can't shut down %s backup driver

   * Error: `1671' SQLSTATE: `HY000' (`ER_BACKUP_STOP_RESTORE_DRIVERS')

     Message: Can't shut down %s backup driver(s)

   * Error: `1672' SQLSTATE: `HY000' (`ER_BACKUP_PREPARE_DRIVER')

     Message: %s backup driver can't prepare for synchronization

   * Error: `1673' SQLSTATE: `HY000' (`ER_BACKUP_CREATE_VP')

     Message: %s backup driver can't create its validity point

   * Error: `1674' SQLSTATE: `HY000' (`ER_BACKUP_UNLOCK_DRIVER')

     Message: Can't unlock %s backup driver after creating the validity
     point

   * Error: `1675' SQLSTATE: `HY000' (`ER_BACKUP_CANCEL_BACKUP')

     Message: %s backup driver can't cancel its backup operation

   * Error: `1676' SQLSTATE: `HY000' (`ER_BACKUP_CANCEL_RESTORE')

     Message: %s restore driver can't cancel its restore operation

   * Error: `1677' SQLSTATE: `HY000' (`ER_BACKUP_GET_DATA')

     Message: Error when polling %s backup driver for its data

   * Error: `1678' SQLSTATE: `HY000' (`ER_BACKUP_SEND_DATA')

     Message: Error when sending data (for table #%d) to %s restore
     driver

   * Error: `1679' SQLSTATE: `HY000' (`ER_BACKUP_SEND_DATA_RETRY')

     Message: After %d attempts %s restore driver still can't accept
     next block of data

   * Error: `1680' SQLSTATE: `HY000' (`ER_BACKUP_OPEN_TABLES')

     Message: Open and lock tables failed in %s

   * Error: `1681' SQLSTATE: `HY000' (`ER_BACKUP_THREAD_INIT')

     Message: Backup driver's table locking thread can not be
     initialized.

   * Error: `1682' SQLSTATE: `HY000' (`ER_BACKUP_PROGRESS_TABLES')

     Message: Can't open the backup logs as tables. Check
     'mysql.backup_history' and 'mysql.backup_progress' or run
     mysql_upgrade to repair.

   * Error: `1683' SQLSTATE: `HY000' (`ER_TABLESPACE_EXIST')

     Message: Tablespace '%s' already exists

   * Error: `1684' SQLSTATE: `HY000' (`ER_NO_SUCH_TABLESPACE')

     Message: Tablespace '%s' doesn't exist

   * Error: `1685' SQLSTATE: `HY000' (`ER_SLAVE_IGNORE_SERVER_IDS')

     Message: The requested server id %d clashes with the slave startup
     option -replicate-same-server-id

   * Error: `1686' SQLSTATE: `HY000' (`ER_BACKUP_CANT_FIND_SE')

     Message: Backup image contains data created by a native driver of
     %s storage engine but this engine can not be found on this server

   * Error: `1687' SQLSTATE: `HY000' (`ER_BACKUP_NO_NATIVE_BE')

     Message: Backup image contains data created by a native driver of
     %s storage engine but it has no native backup support on this
     server

   * Error: `1688' SQLSTATE: `HY000' (`ER_BACKUP_UNKNOWN_BE')

     Message: Backup engine #%d needed for restoring from backup image
     has unknown type

   * Error: `1689' SQLSTATE: `HY000' (`ER_BACKUP_WRONG_TABLE_BE')

     Message: Backup image specifies wrong backup engine #%d for one of
     the tables

   * Error: `1690' SQLSTATE: `HY000' (`ER_BACKUP_CANT_RESTORE_DB')

     Message: Could not restore database %s

   * Error: `1691' SQLSTATE: `HY000' (`ER_BACKUP_CANT_RESTORE_TABLE')

     Message: Could not restore table %s

   * Error: `1692' SQLSTATE: `HY000' (`ER_BACKUP_CANT_RESTORE_VIEW')

     Message: Could not restore view %s. Please check the view
     definition for possible missing dependencies.

   * Error: `1693' SQLSTATE: `HY000' (`ER_BACKUP_CANT_RESTORE_SROUT')

     Message: Could not restore stored routine %s

   * Error: `1694' SQLSTATE: `HY000' (`ER_BACKUP_CANT_RESTORE_EVENT')

     Message: Could not restore event %s

   * Error: `1695' SQLSTATE: `HY000' (`ER_BACKUP_CANT_RESTORE_TRIGGER')

     Message: Could not restore trigger %s

   * Error: `1696' SQLSTATE: `HY000' (`ER_BACKUP_CATALOG_ADD_DB')

     Message: Failed to add database `%s` to the catalog

   * Error: `1697' SQLSTATE: `HY000' (`ER_BACKUP_CATALOG_ADD_TABLE')

     Message: Failed to add table `%s`.`%s` to the catalog

   * Error: `1698' SQLSTATE: `HY000' (`ER_BACKUP_CATALOG_ADD_VIEW')

     Message: Failed to add view `%s`.`%s` to the catalog

   * Error: `1699' SQLSTATE: `HY000' (`ER_BACKUP_CATALOG_ADD_SROUT')

     Message: Failed to add stored routine `%s`.`%s` to the catalog

   * Error: `1700' SQLSTATE: `HY000' (`ER_BACKUP_CATALOG_ADD_EVENT')

     Message: Failed to add event `%s`.`%s` to the catalog

   * Error: `1701' SQLSTATE: `HY000' (`ER_BACKUP_CATALOG_ADD_TRIGGER')

     Message: Failed to add trigger `%s`.`%s` to the catalog

   * Error: `1702' SQLSTATE: `HY000' (`ER_BACKUP_UNKNOWN_OBJECT')

     Message: Backup image refers to an object which could not be found
     in the catalog

   * Error: `1703' SQLSTATE: `HY000' (`ER_BACKUP_UNKNOWN_OBJECT_TYPE')

     Message: Backup image refers to an object of unknown type

   * Error: `1704' SQLSTATE: `HY000' (`ER_BACKUP_OPEN_WR')

     Message: Cannot open backup stream for writing

   * Error: `1705' SQLSTATE: `HY000' (`ER_BACKUP_OPEN_RD')

     Message: Cannot open backup stream for reading

   * Error: `1706' SQLSTATE: `HY000' (`ER_BACKUP_BAD_MAGIC')

     Message: Could not find correct signature at the beginning of
     backup stream

   * Error: `1707' SQLSTATE: `HY000' (`ER_BACKUP_CONTEXT_CREATE')

     Message: Cannot create backup/restore execution context

   * Error: `1708' SQLSTATE: `HY000' (`ER_BACKUP_CONTEXT_REMOVE')

     Message: Error when cleaning up after backup/restore operation

   * Error: `1709' SQLSTATE: `HY000' (`ER_BAD_PATH')

     Message: Malformed file path '%s'

   * Error: `1710' SQLSTATE: `HY000' (`ER_DDL_BLOCK')

     Message: Erorr when attempting to block DDLs

   * Error: `1711' SQLSTATE: `HY000' (`ER_BACKUP_LOGGER_INIT')

     Message: Could not initialize logging and reporting services

   * Error: `1712' SQLSTATE: `HY000' (`ER_BACKUP_WRITE_SUMMARY')

     Message: Error when writing summary section of backup image

   * Error: `1713' SQLSTATE: `HY000' (`ER_BACKUP_READ_SUMMARY')

     Message: Error when reading summary section of backup image

   * Error: `1714' SQLSTATE: `HY000' (`ER_BACKUP_GET_META_DB')

     Message: Failed to obtain meta-data for database %s

   * Error: `1715' SQLSTATE: `HY000' (`ER_BACKUP_GET_META_TABLE')

     Message: Failed to obtain meta-data for table %s

   * Error: `1716' SQLSTATE: `HY000' (`ER_BACKUP_GET_META_VIEW')

     Message: Failed to obtain meta-data for view %s

   * Error: `1717' SQLSTATE: `HY000' (`ER_BACKUP_GET_META_SROUT')

     Message: Failed to obtain meta-data for stored routine %s

   * Error: `1718' SQLSTATE: `HY000' (`ER_BACKUP_GET_META_EVENT')

     Message: Failed to obtain meta-data for event %s

   * Error: `1719' SQLSTATE: `HY000' (`ER_BACKUP_GET_META_TRIGGER')

     Message: Failed to obtain meta-data for trigger %s

   * Error: `1720' SQLSTATE: `HY000' (`ER_BACKUP_CREATE_BE')

     Message: Cannot create backup engine for storage engine %s

   * Error: `1721' SQLSTATE: `HY000' (`ER_BACKUP_LIST_PERDB')

     Message: Can't enumerate per database objects

   * Error: `1722' SQLSTATE: `HY000' (`ER_BACKUP_LIST_DB_VIEWS')

     Message: Can't enumerate views in database `%s`

   * Error: `1723' SQLSTATE: `HY000' (`ER_BACKUP_LIST_DB_SROUT')

     Message: Can't enumerate stored routines in database `%s`

   * Error: `1724' SQLSTATE: `HY000' (`ER_BACKUP_LIST_DB_EVENTS')

     Message: Can't enumerate events in database `%s`

   * Error: `1725' SQLSTATE: `HY000' (`ER_BACKUP_LIST_DB_TRIGGERS')

     Message: Can't enumerate triggers in database `%s`

   * Error: `1726' SQLSTATE: `HY000' (`ER_BACKUP_LOG_WRITE_ERROR')

     Message: Can't write to the online backup progress log %s.

   * Error: `1727' SQLSTATE: `HY000' (`ER_TABLESPACE_NOT_EMPTY')

     Message: Tablespace '%s' not empty

   * Error: `1728' SQLSTATE: `HY000' (`ER_BACKUP_CAT_ENUM')

     Message: Could not access the contents of the backup catalog when
     writing backup image preamble

   * Error: `1729' SQLSTATE: `HY000' (`ER_BACKUP_CANT_RESTORE_TS')

     Message: Could not create tablespace %s needed by tables being
     restored.

   * Error: `1730' SQLSTATE: `HY000' (`ER_BACKUP_TS_CHANGE')

     Message: Tablespace %s needed by tables being restored, but the
     current tablespace definition differs from how it was when backup
     was made.

   * Error: `1731' SQLSTATE: `HY000' (`ER_BACKUP_GET_META_TS')

     Message: Failed to obtain meta-data for tablespace %s.

   * Error: `1732' SQLSTATE: `HY000' (`ER_TABLESPACE_DATAFILE_EXIST')

     Message: Tablespace data file '%s' already exists

   * Error: `1733' SQLSTATE: `HY000' (`ER_BACKUP_CATALOG_ADD_TS')

     Message: Failed to add tablespace `%s` to the catalog

   * Error: `1734' SQLSTATE: `HY000' (`ER_DEBUG_SYNC_TIMEOUT')

     Message: debug sync point wait timed out

   * Error: `1735' SQLSTATE: `HY000' (`ER_DEBUG_SYNC_HIT_LIMIT')

     Message: debug sync point hit limit reached

   * Error: `1736' SQLSTATE: `HY000'
     (`ER_BACKUP_FAILED_TO_INIT_COMPRESSION')

     Message: Could not initialize compression of backup image
     (function deflateInit2 returned error code %d: %s)

   * Error: `1737' SQLSTATE: `HY000'
     (`ER_BACKUP_OBTAIN_NAME_LOCK_FAILED')

     Message: Restore failed to obtain the name locks on the tables.

   * Error: `1738' SQLSTATE: `HY000'
     (`ER_BACKUP_RELEASE_NAME_LOCK_FAILED')

     Message: Restore failed to release the name locks on the tables.

   * Error: `1739' SQLSTATE: `HY000' (`ER_BACKUP_BACKUPDIR')

     Message: The path specified for the system variable backupdir
     cannot be accessed or is invalid. ref: %s

   * Error: `1740' SQLSTATE: `HY000' (`ER_DDL_TIMEOUT')

     Message: The backup wait timeout has expired for query '%s'.

   * Error: `1741' SQLSTATE: `HY000' (`ER_BACKUP_LIST_DB_PRIV')

     Message: Can't enumerate grants in database '%s'.

   * Error: `1742' SQLSTATE: `HY000' (`ER_BACKUP_CATALOG_ADD_PRIV')

     Message: Failed to add grant '%s' to the catalog

   * Error: `1743' SQLSTATE: `HY000' (`ER_BACKUP_GET_META_PRIV')

     Message: Failed to obtain meta-data for grant '%s'.

   * Error: `1744' SQLSTATE: `HY000' (`ER_BACKUP_CANT_RESTORE_PRIV')

     Message: Could not execute grant '%s'.

   * Error: `1745' SQLSTATE: `HY000' (`ER_BACKUP_GRANT_SKIPPED')

     Message: The grant '%s' for the user %s was skipped because the
     user does not exist.

   * Error: `1746' SQLSTATE: `HY000' (`ER_BACKUP_GRANT_WRONG_DB')

     Message: The grant '%s' failed. Database not included in the
     backup image.

   * Error: `1747' SQLSTATE: `HY000' (`ER_BACKUP_LOGPATHS')

     Message: The log names for backup_history and backup_progress must
     be unique.

   * Error: `1748' SQLSTATE: `HY000' (`ER_BACKUP_LOGPATH_INVALID')

     Message: The path specified for the %s is invalid. ref: %s

   * Error: `1749' SQLSTATE: `HY000' (`ER_BACKUP_SEND_REPLY')

     Message: Failed to send reply to client after successful %s
     operation

   * Error: `1750' SQLSTATE: `HY000' (`ER_BACKUP_CLOSE')

     Message: Backup/Restore: Error on close of backup stream

   * Error: `1751' SQLSTATE: `HY000' (`ER_BACKUP_BINLOG')

     Message: Error on accessing binlog during BACKUP

   * Error: `1752' SQLSTATE: `HY000' (`ER_BACKUP_LOG_OUTPUT')

     Message: Removing backup log entries by date or backup_id requires
     logging to tables.

   * Error: `1753' SQLSTATE: `HY000' (`ER_BACKUP_PURGE_DATETIME')

     Message: The datetime specified is invalid for the '%s' command.

   * Error: `1754' SQLSTATE: `HY000' (`ER_BACKUP_LOGS_DELETED')

     Message: Backup log entries deleted:

   * Error: `1755' SQLSTATE: `HY000' (`ER_BACKUP_LOGS_TRUNCATED')

     Message: All backup log entries have been deleted

   * Error: `1756' SQLSTATE: `HY000' (`ER_MASTER_BLOCKING_SLAVES')

     Message: The master is not allowing slave connections.

   * Error: `1757' SQLSTATE: `HY000' (`ER_RESTORE_ON_MASTER')

     Message: A restore operation was initiated on the master.

   * Error: `1758' SQLSTATE: `HY000' (`ER_RESTORE_ON_SLAVE')

     Message: A restore operation was attempted on a slave during
     replication. You must stop the slave prior to running a restore.

   * Error: `1759' SQLSTATE: `42000' (`ER_NONUNIQ_DB')

     Message: Not unique database: '%s'

   * Error: `1760' SQLSTATE: `HY000' (`ER_RESTORE_DB_EXISTS')

     Message: Database \'%s\' already exists. Use OVERWRITE flag to
     overwrite.

   * Error: `1761' SQLSTATE: `HY000' (`ER_QUERY_CACHE_DISABLED')

     Message: Query cache is disabled; restart the server with
     query_cache_type=1 to enable it

   * Error: `1762' SQLSTATE: `HY000' (`ER_BACKUP_UNEXPECTED_DATA')

     Message: Backup image contains no tables, but table data was found
     in it

   * Error: `1763' SQLSTATE: `HY000' (`ER_BACKUP_BACKUP_DBS')

     Message: Backing up %u database(s) %s

   * Error: `1764' SQLSTATE: `HY000' (`ER_BACKUP_RESTORE_DBS')

     Message: Restoring %u database(s) %s

   * Error: `1765' SQLSTATE: `HY000' (`ER_COM_UNSUPPORTED')

     Message: %s doesn't support %s

   * Error: `1766' SQLSTATE: `HY000' (`ER_BACKUP_SYNCHRONIZE')

     Message: Backup failed to synchronize table images.

   * Error: `1767' SQLSTATE: `HY000' (`ER_RESTORE_CANNOT_START_SLAVE')

     Message: Cannot start slave. SLAVE START is blocked by %s.

   * Error: `1768' SQLSTATE: `HY000' (`ER_OPERATION_ABORTED')

     Message: Operation aborted

   * Error: `1769' SQLSTATE: `HY000' (`ER_OPERATION_ABORTED_CORRUPTED')

     Message: Operation aborted - data might be corrupted

   * Error: `1770' SQLSTATE: `42000' (`ER_DUP_SIGNAL_SET')

     Message: Duplicate condition information item '%s'

   * Error: `1771' SQLSTATE: `01000' (`ER_SIGNAL_WARN')

     Message: Unhandled user-defined warning condition

   * Error: `1772' SQLSTATE: `02000' (`ER_SIGNAL_NOT_FOUND')

     Message: Unhandled user-defined not found condition

   * Error: `1773' SQLSTATE: `HY000' (`ER_SIGNAL_EXCEPTION')

     Message: Unhandled user-defined exception condition

   * Error: `1774' SQLSTATE: `0K000'
     (`ER_RESIGNAL_WITHOUT_ACTIVE_HANDLER')

     Message: RESIGNAL when handler not active

   * Error: `1775' SQLSTATE: `HY000' (`ER_SIGNAL_BAD_CONDITION_TYPE')

     Message: SIGNAL/RESIGNAL can only use a CONDITION defined with
     SQLSTATE

   * Error: `1776' SQLSTATE: `HY000' (`WARN_COND_ITEM_TRUNCATED')

     Message: Data truncated for condition item '%s'

   * Error: `1777' SQLSTATE: `HY000' (`ER_COND_ITEM_TOO_LONG')

     Message: Data too long for condition item '%s'

   * Error: `1778' SQLSTATE: `HY000' (`ER_PATH_LENGTH')

     Message: The path specified for %s is too long.


File: manual.info,  Node: error-messages-client,  Prev: error-messages-server,  Up: error-handling

B.4 Client Error Codes and Messages
===================================

Client error information comes from the following source files:

   * The Error values and the symbols in parentheses correspond to
     definitions in the `include/errmsg.h' MySQL source file.

   * The Message values correspond to the error messages that are
     listed in the `libmysql/errmsg.c' file.  `%d' and `%s' represent
     numbers and strings, respectively, that are substituted into the
     messages when they are displayed.

Because updates are frequent, it is possible that those files will
contain additional error information not listed here.

   * Error: `2000' (`CR_UNKNOWN_ERROR')

     Message: Unknown MySQL error

   * Error: `2001' (`CR_SOCKET_CREATE_ERROR')

     Message: Can't create UNIX socket (%d)

   * Error: `2002' (`CR_CONNECTION_ERROR')

     Message: Can't connect to local MySQL server through socket '%s'
     (%d)

   * Error: `2003' (`CR_CONN_HOST_ERROR')

     Message: Can't connect to MySQL server on '%s' (%d)

   * Error: `2004' (`CR_IPSOCK_ERROR')

     Message: Can't create TCP/IP socket (%d)

   * Error: `2005' (`CR_UNKNOWN_HOST')

     Message: Unknown MySQL server host '%s' (%d)

   * Error: `2006' (`CR_SERVER_GONE_ERROR')

     Message: MySQL server has gone away

   * Error: `2007' (`CR_VERSION_ERROR')

     Message: Protocol mismatch; server version = %d, client version =
     %d

   * Error: `2008' (`CR_OUT_OF_MEMORY')

     Message: MySQL client ran out of memory

   * Error: `2009' (`CR_WRONG_HOST_INFO')

     Message: Wrong host info

   * Error: `2010' (`CR_LOCALHOST_CONNECTION')

     Message: Localhost via UNIX socket

   * Error: `2011' (`CR_TCP_CONNECTION')

     Message: %s via TCP/IP

   * Error: `2012' (`CR_SERVER_HANDSHAKE_ERR')

     Message: Error in server handshake

   * Error: `2013' (`CR_SERVER_LOST')

     Message: Lost connection to MySQL server during query

   * Error: `2014' (`CR_COMMANDS_OUT_OF_SYNC')

     Message: Commands out of sync; you can't run this command now

   * Error: `2015' (`CR_NAMEDPIPE_CONNECTION')

     Message: Named pipe: %s

   * Error: `2016' (`CR_NAMEDPIPEWAIT_ERROR')

     Message: Can't wait for named pipe to host: %s pipe: %s (%lu)

   * Error: `2017' (`CR_NAMEDPIPEOPEN_ERROR')

     Message: Can't open named pipe to host: %s pipe: %s (%lu)

   * Error: `2018' (`CR_NAMEDPIPESETSTATE_ERROR')

     Message: Can't set state of named pipe to host: %s pipe: %s (%lu)

   * Error: `2019' (`CR_CANT_READ_CHARSET')

     Message: Can't initialize character set %s (path: %s)

   * Error: `2020' (`CR_NET_PACKET_TOO_LARGE')

     Message: Got packet bigger than 'max_allowed_packet' bytes

   * Error: `2021' (`CR_EMBEDDED_CONNECTION')

     Message: Embedded server

   * Error: `2022' (`CR_PROBE_SLAVE_STATUS')

     Message: Error on SHOW SLAVE STATUS:

   * Error: `2023' (`CR_PROBE_SLAVE_HOSTS')

     Message: Error on SHOW SLAVE HOSTS:

   * Error: `2024' (`CR_PROBE_SLAVE_CONNECT')

     Message: Error connecting to slave:

   * Error: `2025' (`CR_PROBE_MASTER_CONNECT')

     Message: Error connecting to master:

   * Error: `2026' (`CR_SSL_CONNECTION_ERROR')

     Message: SSL connection error

   * Error: `2027' (`CR_MALFORMED_PACKET')

     Message: Malformed packet

   * Error: `2028' (`CR_WRONG_LICENSE')

     Message: This client library is licensed only for use with MySQL
     servers having '%s' license

   * Error: `2029' (`CR_NULL_POINTER')

     Message: Invalid use of null pointer

   * Error: `2030' (`CR_NO_PREPARE_STMT')

     Message: Statement not prepared

   * Error: `2031' (`CR_PARAMS_NOT_BOUND')

     Message: No data supplied for parameters in prepared statement

   * Error: `2032' (`CR_DATA_TRUNCATED')

     Message: Data truncated

   * Error: `2033' (`CR_NO_PARAMETERS_EXISTS')

     Message: No parameters exist in the statement

   * Error: `2034' (`CR_INVALID_PARAMETER_NO')

     Message: Invalid parameter number

   * Error: `2035' (`CR_INVALID_BUFFER_USE')

     Message: Can't send long data for non-string/non-binary data types
     (parameter: %d)

   * Error: `2036' (`CR_UNSUPPORTED_PARAM_TYPE')

     Message: Using unsupported buffer type: %d (parameter: %d)

   * Error: `2037' (`CR_SHARED_MEMORY_CONNECTION')

     Message: Shared memory: %s

   * Error: `2038' (`CR_SHARED_MEMORY_CONNECT_REQUEST_ERROR')

     Message: Can't open shared memory; client could not create request
     event (%lu)

   * Error: `2039' (`CR_SHARED_MEMORY_CONNECT_ANSWER_ERROR')

     Message: Can't open shared memory; no answer event received from
     server (%lu)

   * Error: `2040' (`CR_SHARED_MEMORY_CONNECT_FILE_MAP_ERROR')

     Message: Can't open shared memory; server could not allocate file
     mapping (%lu)

   * Error: `2041' (`CR_SHARED_MEMORY_CONNECT_MAP_ERROR')

     Message: Can't open shared memory; server could not get pointer to
     file mapping (%lu)

   * Error: `2042' (`CR_SHARED_MEMORY_FILE_MAP_ERROR')

     Message: Can't open shared memory; client could not allocate file
     mapping (%lu)

   * Error: `2043' (`CR_SHARED_MEMORY_MAP_ERROR')

     Message: Can't open shared memory; client could not get pointer to
     file mapping (%lu)

   * Error: `2044' (`CR_SHARED_MEMORY_EVENT_ERROR')

     Message: Can't open shared memory; client could not create %s
     event (%lu)

   * Error: `2045' (`CR_SHARED_MEMORY_CONNECT_ABANDONED_ERROR')

     Message: Can't open shared memory; no answer from server (%lu)

   * Error: `2046' (`CR_SHARED_MEMORY_CONNECT_SET_ERROR')

     Message: Can't open shared memory; cannot send request event to
     server (%lu)

   * Error: `2047' (`CR_CONN_UNKNOW_PROTOCOL')

     Message: Wrong or unknown protocol

   * Error: `2048' (`CR_INVALID_CONN_HANDLE')

     Message: Invalid connection handle

   * Error: `2049' (`CR_SECURE_AUTH')

     Message: Connection using old (pre-4.1.1) authentication protocol
     refused (client option 'secure_auth' enabled)

   * Error: `2050' (`CR_FETCH_CANCELED')

     Message: Row retrieval was canceled by mysql_stmt_close() call

   * Error: `2051' (`CR_NO_DATA')

     Message: Attempt to read column without prior row fetch

   * Error: `2052' (`CR_NO_STMT_METADATA')

     Message: Prepared statement contains no metadata

   * Error: `2053' (`CR_NO_RESULT_SET')

     Message: Attempt to read a row while there is no result set
     associated with the statement

   * Error: `2054' (`CR_NOT_IMPLEMENTED')

     Message: This feature is not implemented yet

   * Error: `2055' (`CR_SERVER_LOST_EXTENDED')

     Message: Lost connection to MySQL server at '%s', system error: %d

   * Error: `2056' (`CR_STMT_CLOSED')

     Message: Statement closed indirectly because of a preceeding %s()
     call

   * Error: `2057' (`CR_NEW_STMT_METADATA')

     Message: The number of columns in the result set differs from the
     number of bound buffers. You must reset the statement, rebind the
     result set columns, and execute the statement again

   * Error: `2058' (`CR_ALREADY_CONNECTED')

     Message: This handle is already connected. Use a separate handle
     for each connection.


File: manual.info,  Node: news,  Next: restrictions,  Prev: error-handling,  Up: Top

Appendix C MySQL Change History
*******************************

* Menu:

* news-6-0-x::                   Changes in release 6.0.x (Development)
* news-5-2-x::                   Changes in release 5.2.x (Development)
* mem-news::                     MySQL Enterprise Monitor Change History
* connector-odbc-news::          MySQL Connector/ODBC (MyODBC) Change History
* connector-net-news::           MySQL Connector/NET Change History
* vstudio-plugin-news::          MySQL Visual Studio Plugin Change History
* cj-news::                      MySQL Connector/J Change History
* news-connector-mxj::           MySQL Connector/MXJ Change History
* ccpp-news::                    MySQL Connector/C++ Change History
* mysql-proxy-news::             MySQL Proxy Change History

This appendix lists the changes from version to version in the MySQL
source code through the latest version of MySQL 6.0, which is currently
MySQL 6.0.12. Starting with MySQL 5.0, we began offering a new version
of the Manual for each new series of MySQL releases (5.0, 5.1, and so
on). For information about changes in previous release series of the
MySQL database software, see the corresponding version of this Manual.
For information about legacy versions of the MySQL software through the
4.1 series, see `MySQL 3.23, 4.0, 4.1 Reference Manual'.

We update this section as we add new features in the 6.0 series, so
that everybody can follow the development process.

Note that we tend to update the manual at the same time we make changes
to MySQL. If you find a recent version of MySQL listed here that you
can't find on our download page (`http://dev.mysql.com/downloads/'), it
means that the version has not yet been released.

The date mentioned with a release version is the date of the last
Bazaar commit on which the release was based, not the date when the
packages were made available. The binaries are usually made available a
few days after the date of the tagged ChangeSet, because building and
testing all packages takes some time.

The manual included in the source and binary distributions may not be
fully accurate when it comes to the release changelog entries, because
the integration of the manual happens at build time. For the most
up-to-date release changelog, please refer to the online version
instead.


File: manual.info,  Node: news-6-0-x,  Next: news-5-2-x,  Prev: news,  Up: news

C.1 Changes in release 6.0.x (Development)
==========================================

* Menu:

* news-6-0-11::                  Changes in MySQL 6.0.11 (Not yet released)
* news-6-0-10::                  Changes in MySQL 6.0.10 (03 March 2009)
* news-6-0-9::                   Changes in MySQL 6.0.9 (10 January 2009)
* news-6-0-8::                   Changes in MySQL 6.0.8 (03 November 2008)
* news-6-0-7::                   Changes in MySQL 6.0.7 (29 September 2008)
* news-6-0-6::                   Changes in MySQL 6.0.6 (11 August 2008)
* news-6-0-5::                   Changes in MySQL 6.0.5 (12 June 2008)
* news-6-0-4::                   Changes in MySQL 6.0.4 (12 February 2008)
* news-6-0-3::                   Changes in MySQL 6.0.3 (16 November 2007)
* news-6-0-2::                   Changes in MySQL 6.0.2 (04 September 2007)
* news-6-0-1::                   Changes in MySQL 6.0.1 (Not released)
* news-6-0-0::                   Changes in MySQL 6.0.0 (30 April 2007 Alpha)

An overview of which features were added in MySQL 6.0 can be found
here: *Note mysql-nutshell::.

For a full list of changes, please refer to the changelog sections for
each individual 6.0.x release.


File: manual.info,  Node: news-6-0-11,  Next: news-6-0-10,  Prev: news-6-0-x,  Up: news-6-0-x

C.1.1 Changes in MySQL 6.0.11 (Not yet released)
------------------------------------------------

Functionality added or changed:

   * *Incompatible Change*: The `optimizer_switch' system variable
     controls optimizations that can be switched on and off.  The
     syntax for flags in its value has changed from `'no_OPT_NAME'' to
     `'OPT_NAME={on|off|default}''.  For information about the new
     syntax, see *Note switchable-optimizations::.

   * *Replication*: The global server variables `sync_master_info' and
     `sync_relay_log_info' are introduced for use on replication slaves
     to control synchronization of, respectively, the `master.info' and
     `relay.info' files.

     In each case, setting the variable to a nonzero integer value N
     causes the slave to synchonize the corresponding file to disk
     after every N events. Setting its value to 0 allows the operation
     system to handle syncronization of the file instead.

     The actions of these variables, when enabled, are analogous to how
     the `sync_binlog' variable works with regard to binary logs on a
     replication master.

     These variables can also be set in `my.cnf', or by using the
     server options `--sync-master-info' and `--sync-relay-log-info'
     respectively.

     An additional system variable `relay_log_recovery' is also now
     available. When enabled, this variable causes a replication slave
     to discard relay log files obtained from the replication master
     following a crash.

     This variable can also be set in `my.cnf', or by using the
     `--relay-log-recovery' server option.

     This fix improves and expands upon one made in MySQL 6.0.10 which
     introduced the `sync_relay_log' variable. For more information
     about all of the server system variables introduced by these
     fixes, see *Note replication-options-slave::.  (Bug#31665
     (http://bugs.mysql.com/31665), Bug#35542
     (http://bugs.mysql.com/35542), Bug#40337
     (http://bugs.mysql.com/40337))

   * `mysql-test-run.pl' now supports an `--experimental=FILE_NAME'
     option. It enables you to specify a file that contains a list of
     test cases that should be displayed with the `[ exp-fail ]' code
     rather than `[ fail ]' if they fail.  (Bug#42888
     (http://bugs.mysql.com/42888))

   * The MD5 algorithm now uses the Xfree implementation.  (Bug#42434
     (http://bugs.mysql.com/42434))

   * The *Note `RESTORE': restore. statement now has a `SKIP_GAP_EVENT'
     option that causes the restore operation not to write the gap
     event to the binary log that causes any replication slaves to stop
     replication. This is useful when *Note `RESTORE': restore. is run
     on a master server and the backup image does not contain databases
     that are replicated to the slaves.  (Bug#39780
     (http://bugs.mysql.com/39780))

   * Previously, the `--secure-file-priv' option and `secure_file_priv'
     system variable, if set to a directory, limited `BACKUP DATABASE'
     and `RESTORE' operations to files in the given directory. Now the
     `--secure-backup-file-priv' option and `secure_backup_file_priv'
     system variable apply instead.  (Bug#39581
     (http://bugs.mysql.com/39581))

   * The query cache now checks whether a *Note `SELECT': select.
     statement begins with `SQL_NO_CACHE' to determine whether it can
     skip checking for the query result in the query cache. This is not
     supported when `SQL_NO_CACHE' occurs within a comment.  (Bug#37416
     (http://bugs.mysql.com/37416))

   * A new program, *Note `mysqlbackup': mysqlbackup, displays
     information from backups created with the *Note `BACKUP DATABASE':
     backup-database. statement.

   * MySQL now implements the SQL standard *Note `SIGNAL': signal. and
     *Note `RESIGNAL': resignal. statements. See *Note
     signal-resignal::.

Bugs fixed:

   * *Incompatible Change*: For system variables that take values of
     `ON' or `OFF', `OF' was accepted as a legal variable. Now system
     variables that take `enumeration' values must be assigned the full
     value. This affects some other variables that previously could be
     assigned using unambiguous prefixes of allowable values, such as
     `tx_isolation'.  (Bug#34828 (http://bugs.mysql.com/34828))

   * *Incompatible Change*: If a data definition language (DDL)
     statement occurred for a table that was being used by another
     session in an active transaction, statements could be written to
     the binary log in the wrong order. For example, this could happen
     if `DROP TABLE' occurred for a table being used in a transaction.
     This is now prevented by deferring release of metadata locks on
     tables used within a transaction until the transaction ends.

     This bug fix results in some incompatibilities with previous
     versions:

        * A table that is being used by a transaction within one
          session cannot be used in DDL statements by other sessions
          until the transaction ends.

        * *Note `FLUSH TABLES WITH READ LOCK': flush. blocks for active
          transactions that hold metadata locks until those
          transactions end. The same is true for attempts to set the
          global value of the `read_only' system variable.

     (Bug#989 (http://bugs.mysql.com/989))

   * *Important Change*: *Replication*: *Note `CHANGE MASTER TO ...
     MASTER_HOST=''': change-master-to. -- explicitly setting
     `MASTER_HOST' equal to an empty string -- created a `master.info'
     file with an empty `host' field. This led to a `The server is not
     configured as slave' error when attempting to execute a *Note
     `START SLAVE': start-slave. statement. Now, if `MASTER_HOST' is
     set to an empty string, the *Note `CHANGE MASTER TO':
     change-master-to. statement fails with an error.  (Bug#28796
     (http://bugs.mysql.com/28796))

   * *Replication*: *Important Note*: Binary logging with
     `--binlog_format=ROW' failed when a change to be logged included
     more than 251 columns. This issue was not known to occur with
     mixed-format or statement-based logging.  (Bug#42977
     (http://bugs.mysql.com/42977)) See also Bug#42914
     (http://bugs.mysql.com/42914).

   * *Replication*: The *Note `SHOW SLAVE STATUS': show-slave-status.
     connection thread competed with the slave SQL thread for use of
     the error message buffer. As a result, the connection thread
     sometimes received incomplete messages. This issue was uncovered
     with `valgrind' when message strings were passed without `NULL'
     terminators, causing the error `Conditional jump or move depends
     on uninitialised value(s)'.  (Bug#43076
     (http://bugs.mysql.com/43076))

   * *Replication*: This fix handles 2 issues encountered on
     replication slaves during startup:

       1. A failure while allocating the master info structure caused
          the slave to crash.

       2. A failure during recovery caused the relay log file not to be
          properly initialized which led to a crash on the slave.

     (Bug#43075 (http://bugs.mysql.com/43075))

   * *Replication*: Assigning an invalid directory for the
     `--slave-load-tmpdir' caused the replication slave to crash.
     (Bug#42861 (http://bugs.mysql.com/42861))

   * *Replication*: The `mysql.procs_priv' system table was not
     replicated.  (Bug#42217 (http://bugs.mysql.com/42217))

   * *Replication*: When `--binlog_format' was set to `STATEMENT', a
     statement unsafe for statement-based logging caused an error or
     warning to be issued even if `sql_log_bin' was set to 0.
     (Bug#41980 (http://bugs.mysql.com/41980))

   * *Replication*: An *Note `INSERT DELAYED': insert. into a *Note
     `TIMESTAMP': datetime. column issued concurrently with a an insert
     on the same column not using `DELAYED', but applied after the
     other insert, was logged using the same timestamp as generated by
     the other (non-`DELAYED') insert.  (Bug#41719
     (http://bugs.mysql.com/41719))

   * *Replication*: When using `MIXED' replication format and temporary
     tables were created in statement-based mode, but a later operation
     in the same session caused a switch to row-based mode, the
     temporary tables were not dropped on the slave at the end of the
     session.  (Bug#40013 (http://bugs.mysql.com/40013)) See also
     Bug#43046 (http://bugs.mysql.com/43046).

     This regression was introduced by Bug#20499
     (http://bugs.mysql.com/20499).

   * *Replication*: When using the `MIXED' replication format, *Note
     `UPDATE': update. and *Note `DELETE': delete. statements that
     searched for rows where part of the key had nullable *Note `BIT':
     numeric-types. columns failed. This occurred because operations
     that inserted the data were replicated as statements, but *Note
     `UPDATE': update. and *Note `DELETE': delete. statements affecting
     the same data were replicated using row-based format.

     This issue did not occur when using statement-based replication
     (only) or row-based replication (only).  (Bug#39753
     (http://bugs.mysql.com/39753)) See also Bug#39648
     (http://bugs.mysql.com/39648).

   * *Replication*: The `MIXED' binary logging format did not switch to
     row-based mode for statements containing the `LOAD_FILE()'
     function.  (Bug#39701 (http://bugs.mysql.com/39701))

   * *Replication*: The server SQL mode in effect when a stored
     procedure was created was not retained in the binary log. This
     could cause a *Note `CREATE PROCEDURE': create-procedure.
     statement that succeeded on the master to fail on the slave.

     This issue was first noticed when a stored procedure was created
     when `ANSI_QUOTES' was in effect on the master, but could possibly
     cause failed *Note `CREATE PROCEDURE': create-procedure.
     statements and other problems on the slave when using other server
     SQL modes as well.  (Bug#39526 (http://bugs.mysql.com/39526))

   * *Replication*: If `--secure-file-priv' was set on the slave, it
     was unable to execute *Note `LOAD DATA INFILE': load-data.
     statements sent from the master when using mixed-format or
     statement-based replication.

     As a result of this fix, this security restriction is now ignored
     on the slave in such cases; instead the slave checks whether the
     files were created and should be read by the slave in its
     `--slave-load-tmpdir'.  (Bug#38174 (http://bugs.mysql.com/38174))

   * *Replication*: Server IDs greater than 2147483647 (2^32 - 1) were
     represented by negative numbers in the binary log.  (Bug#37313
     (http://bugs.mysql.com/37313))

   * *Replication*: The value of `Slave_IO_running' in the output of
     *Note `SHOW SLAVE STATUS': show-slave-status. did not distinguish
     between all 3 possible states of the slave I/O thread (not
     running; running but not connected; connected). Now the value
     `Connecting' (rather than `No') is shown when the slave I/O thread
     is running but the slave is not connected to a replication master.

     The server system variable `Slave_running' also reflects this
     change, and is now consistent with what is shown for
     `Slave_IO_running'.  (Bug#30703 (http://bugs.mysql.com/30703),
     Bug#41613 (http://bugs.mysql.com/41613))

   * *Replication*: Queries which were written to the slow query log on
     the master were not written to the slow query log on the slave.
     (Bug#23300 (http://bugs.mysql.com/23300))

   * *Replication*: When the server SQL mode included `IGNORE_SPACE',
     statement-based replication of *Note `LOAD DATA INFILE ... INTO
     TBL_NAME': load-data. failed because the statement was read
     incorrectly from the binary log; a trailing space was omitted,
     causing the statement to fail with a syntax error when run on the
     slave.  (Bug#22504 (http://bugs.mysql.com/22504)) See also
     Bug#43746 (http://bugs.mysql.com/43746).

   * *Replication*: When its disk becomes full, a replication slave may
     wait while writing the binary log, relay log or `MyISAM' tables,
     continuing after space has been made available. The error message
     provided in such cases was not clear about the frequency with
     which checking for free space is done (once every 60 seconds), and
     how long the server waits after space has been freed before
     continuing (also 60 seconds); this caused users to think that the
     server had hung.

     These issues have been addressed by making the error message
     clearer, and dividing it into two separate messages:

       1. The error message `Disk is full writing 'FILENAME' (Errcode:
          ERROR_CODE). Waiting for someone to free space... (Expect up
          to 60 secs delay for server to continue after freeing disk
          space)' is printed only once.

       2. The warning `Retry in 60 secs, Message reprinted in 600 secs'
          is printed once every for every 10 times that the check for
          free space is made; that is, the check is performed once each
          60 seconds, but the reminder that space needs to be freed is
          printed only once every 10 minutes (600 seconds).

     (Bug#22082 (http://bugs.mysql.com/22082))

   * Memory corruption of join buffers could occur when using the
     Batched Key Access algorithm with incremental join buffers to
     execute join operations for a query over several tables that
     selects *Note `BLOB': blob. values.  (Bug#44250
     (http://bugs.mysql.com/44250))

   * The server could crash at startup when initializing plugins listed
     in the plugin table.  (Bug#44137 (http://bugs.mysql.com/44137))

   * A *Note `RESTORE': restore. operation that restored a `MyISAM'
     table using the native `MyISAM' restore driver could cause the
     `MyISAM' key cache to be disabled.  (Bug#44068
     (http://bugs.mysql.com/44068))

   * In some cases, when the Batched Key Access algorithm is used with
     `join_cache_level' equal to 6, multi-join queries could return
     incorrect results.  (Bug#44019 (http://bugs.mysql.com/44019))

   * On 64-bit debug builds, code in `safemalloc' resulted in errors
     due to use of a 32-bit value for 64-bit allocations.  (Bug#43885
     (http://bugs.mysql.com/43885))

   * An attempt by a user who did not have the `SUPER' privilege to
     kill a system thread could cause a server crash.  (Bug#43748
     (http://bugs.mysql.com/43748))

   * On Windows, incorrectly specified link dependencies in
     `CMakeLists.txt' resulted in link errors for `mysql_embedded',
     `mysqltest_embedded', and `mysql_client_test_embedded'.
     (Bug#43715 (http://bugs.mysql.com/43715))

   * `make distcheck' failed to properly handle subdirectories of
     `storage/ndb'.  (Bug#43614 (http://bugs.mysql.com/43614))

   * Incorrect use of parser information could lead to acquisition of
     incorrect lock types.  (Bug#43568 (http://bugs.mysql.com/43568))

   * *Note `RESTORE': restore. on a case-insensitive server failed if
     the backup image contained databases or tables with uppercase
     names. Now, *Note `RESTORE': restore. handles this case by
     converting the names to lowercase in the restore catalog, as long
     as there are no duplicate names after the conversion.  (Bug#43363
     (http://bugs.mysql.com/43363))

   * Use of `USE INDEX' hints could cause *Note `EXPLAIN EXTENDED':
     explain. to crash.  (Bug#43354 (http://bugs.mysql.com/43354))

   * *Note `BACKUP DATABASE': backup-database. stored incorrect table
     counts in the backup image.  (Bug#43324
     (http://bugs.mysql.com/43324))

   * Assigning a value to the `backupdir' system variable resulted in
     Valgrind errors.  (Bug#43303 (http://bugs.mysql.com/43303))

   * *Note `mysql': mysql. crashed if a request for the current
     database name returned an empty result, such as after the client
     has executed a preceding `SET sql_select_limit=0' statement.
     (Bug#43254 (http://bugs.mysql.com/43254))

   * If the value of the `version_comment' system variable was too
     long, the *Note `mysql': mysql. client displayed a truncated
     startup message.  (Bug#43153 (http://bugs.mysql.com/43153))

   * Compilation failures on Windows Vista using Visual Studio 2008
     Professional were corrected.  (Bug#43120
     (http://bugs.mysql.com/43120))

   * On 32-bit Windows, *Note `mysqld': mysqld. could not use large
     buffers due to a 2GB user mode address limit.  (Bug#43082
     (http://bugs.mysql.com/43082))

   * The MySQL Backup library had incorrect logic and error reporting
     for metadata saving.  (Bug#42959 (http://bugs.mysql.com/42959))

   * Queries of the following form returned an empty result:

          SELECT ... WHERE ... (COL=COL AND COL=COL) OR ... (FALSE EXPRESSION)

     (Bug#42957 (http://bugs.mysql.com/42957))

   * A two-way join query with a `GROUP BY' or `ORDER BY' clause could
     produce incorrect results when rows of the first table are
     accessed by an index compatible with the `GROUP BY' or `ORDER BY'
     list while the second table is joined using the Batched Key Access
     algorithm.  (Bug#42955 (http://bugs.mysql.com/42955))

   * The `strings/CHARSET_INFO.txt' file was not included in source
     distributions.  (Bug#42937 (http://bugs.mysql.com/42937))

   * `stderr' should be unbuffered, but when the server redirected
     `stderr' to a file, it became buffered.  (Bug#42790
     (http://bugs.mysql.com/42790))

   * The `DATA_TYPE' column of the *Note `INFORMATION_SCHEMA.COLUMNS':
     columns-table. table displayed the `UNSIGNED' attribute for
     floating-point data types. (The column should contain only the
     data type name.)  (Bug#42758 (http://bugs.mysql.com/42758))

   * Use of semijoin optimization could cause a server crash.
     (Bug#42740 (http://bugs.mysql.com/42740))

   * Assigning a value to the `backupdir' system variable resulted in a
     memory leak.  (Bug#42695 (http://bugs.mysql.com/42695))

   * Assigning an incorrect value to the `backup_progress_log_file'
     system variable resulted in Valgrind errors.  (Bug#42685
     (http://bugs.mysql.com/42685))

   * A dangling pointer in `mysys/my_error.c' could lead to client
     crashes.  (Bug#42675 (http://bugs.mysql.com/42675))

   * *Note `mysqldump': mysqldump. included views that were excluded
     with the `--ignore-table' option.  (Bug#42635
     (http://bugs.mysql.com/42635))

   * An earlier bug fix resulted in the problem that the `InnoDB'
     plugin could not be used with a server that was compiled with the
     built-in `InnoDB'.  To handle this two changes were made:

        * The server now supports an `--ignore-builtin-innodb'
          (http://dev.mysql.com/doc/refman/5.1/en/innodb-parameters.html#option_mysqld_ignore-builtin-innodb)
          option that causes the server to behave as if the built-in
          `InnoDB' is not present. This option causes other `InnoDB'
          options not to be recognized.

        * For the *Note `INSTALL PLUGIN': install-plugin.  statement,
          the server reads option (`my.cnf') files just as during server
          startup. This enables the plugin to pick up any relevant
          options from those files. Consequently, a plugin no longer is
          started with each option set to its default value.

          Because of this change, it is possible to add plugin options
          to an option file even before loading a plugin (if the
          `loose' prefix is used). It is also possible to uninstall a
          plugin, edit `my.cnf', and install the plugin again.
          Restarting the plugin this way enables it to the new option
          values without a server restart.

     *Note*:

     `InnoDB' Plugin versions 1.0.4 and higher will take advantage of
     this bug fix. Although the `InnoDB' Plugin is source code
     compatible with multiple MySQL releases, a given binary `InnoDB'
     Plugin can be used only with a specific MySQL release. When
     `InnoDB' Plugin 1.0.4 is released, it is expected to be compiled
     for MySQL 5.1.34. For 5.1.33, you can use `InnoDB' Plugin 1.0.3,
     but you must build from source.

     (Bug#42610 (http://bugs.mysql.com/42610)) This regression was
     introduced by Bug#29263 (http://bugs.mysql.com/29263).

   * With the `ONLY_FULL_GROUP_BY' SQL mode enabled, some legal queries
     failed.  (Bug#42567 (http://bugs.mysql.com/42567))

   * Passing an unknown time zone specification to `CONVERT_TZ()'
     resulted in a memory leak.  (Bug#42502
     (http://bugs.mysql.com/42502))

   * Tables could enter open table cache for a thread without being
     properly cleaned up, leading to a server crash.  (Bug#42419
     (http://bugs.mysql.com/42419))

   * Previously, *Note `RESTORE': restore. would crash if the backup
     image contained tables originally stored in a tablespace that no
     longer existed at *Note `RESTORE': restore. time. Now the
     tablespace is recreated like it was at *Note `BACKUP DATABASE':
     backup-database. time if it does not exist when *Note `RESTORE':
     restore. is executed.  (Bug#42402 (http://bugs.mysql.com/42402))

   * If the server was started with `--thread_handling=pool-of-threads',
     the `MAX_QUERIES_PER_HOUR' user resource limit.  (Bug#42384
     (http://bugs.mysql.com/42384))

   * If the server was started with an option that had a missing or
     invalid value, a subsequent error that would cause normally the
     server to shut down could cause it to crash instead.  (Bug#42244
     (http://bugs.mysql.com/42244))

   * For `InnoDB' tables, there was a race condition for *Note `ALTER
     TABLE': alter-table, *Note `OPTIMIZE TABLE': optimize-table, *Note
     `CREATE INDEX': create-index, and *Note `DROP INDEX': drop-index.
     operations when periodically checking whether table copying can be
     committed.  (Bug#42152 (http://bugs.mysql.com/42152))

   * In `InnoDB' recovery after a server crash, table lookup could fail
     and corrupt the data dictionary cache.  (Bug#42075
     (http://bugs.mysql.com/42075))

   * *Note `mysqldumpslow': mysqldumpslow. parsed the `--debug' and
     `--verbose' options incorrectly.  (Bug#42027
     (http://bugs.mysql.com/42027))

   * *Note `BACKUP DATABASE': backup-database. and *Note `RESTORE':
     restore. did not implement backup and restore of privileges for
     stored procedures and stored functions.  (Bug#41979
     (http://bugs.mysql.com/41979))

   * *Note `RESTORE': restore. crashed for `Falcon' tables.  (Bug#41722
     (http://bugs.mysql.com/41722))

   * With more than two arguments, `LEAST()', `GREATEST()', and `CASE'
     could unnecessarily return `Illegal mix of collations' errors.
     (Bug#41627 (http://bugs.mysql.com/41627))

   * Queries that used the loose index scan access method could return
     no rows.  (Bug#41610 (http://bugs.mysql.com/41610))

   * *Note `RESTORE': restore. failed if it tried to restore a
     privilege for a non-existent object.  (Bug#41578
     (http://bugs.mysql.com/41578))

   * In `InnoDB' recovery after a server crash, rollback of a
     transaction that updated a column from `NULL' to `NULL' could cause
     another crash.  (Bug#41571 (http://bugs.mysql.com/41571))

   * The *Note `mysql': mysql. client could misinterpret its input if a
     line was longer than an internal buffer.  (Bug#41486
     (http://bugs.mysql.com/41486))

   * The error message for a too-long column comment was `Unknown
     error' rather than a more appropriate message.  (Bug#41465
     (http://bugs.mysql.com/41465))

   * Use of `SELECT *' allowed users with rights to only some columns
     of a view to access all columns.  (Bug#41354
     (http://bugs.mysql.com/41354))

   * If the tables underlying a `MERGE' table had a primary key but the
     `MERGE' table itself did not, inserting a duplicate row into the
     `MERGE' table caused a server crash.  (Bug#41305
     (http://bugs.mysql.com/41305))

   * In the `help' command output displayed by *Note `mysql': mysql,
     the description for the `\c' (`clear') command was misleading.
     (Bug#41268 (http://bugs.mysql.com/41268))

   * Several resource leaks were corrected in the error-handling code
     for the MySQL Backup library.  (Bug#41250
     (http://bugs.mysql.com/41250), Bug#41294
     (http://bugs.mysql.com/41294))

   * The server did not robustly handle problems hang if a table opened
     with *Note `HANDLER': handler. needed to be re-opened because it
     had been altered to use a different storage engine that does not
     support *Note `HANDLER': handler. The server also failed to set an
     error if the re-open attempt failed. These problems could cause
     the server to crash or hang.  (Bug#41110
     (http://bugs.mysql.com/41110), Bug#41112
     (http://bugs.mysql.com/41112))

   * *Note `SELECT': select. statements executed concurrently with
     *Note `INSERT': insert.  statements for a `MyISAM' table could
     cause incorrect results to be returned from the query cache.
     (Bug#41098 (http://bugs.mysql.com/41098))

   * For prepared statements, multibyte character sets were not taking
     into account when calculating `max_length' for string values and
     *Note `mysql_stmt_fetch()': mysql-stmt-fetch. could return
     truncated strings.  (Bug#41078 (http://bugs.mysql.com/41078))

   * For user-defined variables in a query result, incorrect length
     values were returned in the result metadata.  (Bug#41030
     (http://bugs.mysql.com/41030))

   * Using *Note `RESTORE': restore. to restore a database through a
     named pipe resulted in corrupt data.  (Bug#40975
     (http://bugs.mysql.com/40975))

   * For some queries, an equality propagation problem could cause `a =
     b' and `b = a' to be handled differently.  (Bug#40925
     (http://bugs.mysql.com/40925))

   * With strict SQL mode enabled, setting a system variable to an
     out-of-bounds value caused an assertion failure.  (Bug#40657
     (http://bugs.mysql.com/40657))

   * Table temporary scans were slower than necessary due to use of
     mmap rather than caching, even with the `myisam_use_mmap' system
     variable disabled.  (Bug#40634 (http://bugs.mysql.com/40634))

   * The `load_defaults()', `my_search_option_files()' and
     `my_print_default_files()' functions in the C client library were
     subject to a race condition in multi-threaded operation.
     (Bug#40552 (http://bugs.mysql.com/40552))

   * For a view that references a table in another database, *Note
     `mysqldump': mysqldump. wrote the view name qualified with the
     current database name. This makes it impossible to reload the dump
     file into a different database.  (Bug#40345
     (http://bugs.mysql.com/40345))

   * On platforms where long and pointer variables have different
     sizes, `MyISAM' could copy key statistics incorrectly, resulting
     in a server crash or incorrect cardinality values.  (Bug#40321
     (http://bugs.mysql.com/40321))

   * *Note `DELETE': delete. tried to acquire write (not read) locks
     for tables accessed within a subquery of the `WHERE' clause.
     (Bug#39843 (http://bugs.mysql.com/39843))

   * *Note `mysql_upgrade': mysql-upgrade. did not remove the
     `online_backup' and `online_backup_progress' tables from the
     `mysql' database. (These are what the `backup_history' and
     `backup_progress' tables were called previously.)  (Bug#39655
     (http://bugs.mysql.com/39655))

   * With row-based binary logging, replication of `InnoDB' tables
     containing `NULL'-valued *Note `BIT': numeric-types. columns could
     fail.  (Bug#39648 (http://bugs.mysql.com/39648))

   * The *Note `mysql_stmt_close()': mysql-stmt-close. C API function
     did not flush all pending data associated with the prepared
     statement.  (Bug#39519 (http://bugs.mysql.com/39519))

   * Following *Note `ALTER TABLE ... DISCARD TABLESPACE': alter-table.
     for an `InnoDB' table, an attempt to determine the free space for
     the table before the *Note `ALTER TABLE': alter-table. operation
     had completely finished could cause a server crash.  (Bug#39438
     (http://bugs.mysql.com/39438))

   * *Note `perror': perror. did not produce correct output for error
     codes 153 to 163.  (Bug#39370 (http://bugs.mysql.com/39370))

   * If `--basedir' was specified, *Note `mysqld_safe': mysqld-safe.
     did not use it when attempting to locate *Note
     `my_print_defaults': my-print-defaults.  (Bug#39326
     (http://bugs.mysql.com/39326))

   * Several functions in `libmysqld' called `exit()' when an error
     occurred rather than returning an error to the caller.  (Bug#39289
     (http://bugs.mysql.com/39289))

   * Previously, the `num_objects' column in the `backup_history' table
     showed only the number of tables in the backup image. It now shows
     the number of objects with names (tablespaces, databases, tables,
     views, stored programs).  (Bug#39109 (http://bugs.mysql.com/39109))

   * *Note `BACKUP DATABASE': backup-database. treated the database
     list in case-sensitive fashion, even on case-insensitive file
     systems.  (Bug#39063 (http://bugs.mysql.com/39063))

   * The `ALTER ROUTINE' privilege incorrectly allowed *Note `SHOW
     CREATE TABLE': show-create-table.  (Bug#38347
     (http://bugs.mysql.com/38347))

   * *Note `BACKUP DATABASE': backup-database. crashed if there was no
     default database.  (Bug#38294 (http://bugs.mysql.com/38294))

   * Setting a savepoint with the same name as an existing savepoint
     incorrectly deleted any other savepoints that had been set in the
     meantime. For example, setting savepoints named `a', `b', `c', `b'
     resulted in savepoints `a', `b', rather than the correct
     savepoints `a', `c', `b'.  (Bug#38187
     (http://bugs.mysql.com/38187))

   * Locking of `myisam.log' did not work correctly on Windows.
     (Bug#38133 (http://bugs.mysql.com/38133), Bug#41224
     (http://bugs.mysql.com/41224))

   * `--help' output for *Note `myisamchk': myisamchk. did not list the
     `--HELP' option.  (Bug#38103 (http://bugs.mysql.com/38103))

   * Setting the session value of the `debug' system variable also set
     the global value.  (Bug#38054 (http://bugs.mysql.com/38054))

   * Comparisons between row constructors, such as `(a, b) = (c, d)'
     resulted in unnecessary `Illegal mix of collations' errors for
     string columns.  (Bug#37601 (http://bugs.mysql.com/37601))

   * A workload consisting of *Note `CREATE TABLE ... SELECT':
     create-table. and DML operations could cause deadlock.  (Bug#37433
     (http://bugs.mysql.com/37433))

   * If a user created a view that referenced tables for which the user
     had disjoint privileges, an assertion failure occurred.
     (Bug#37191 (http://bugs.mysql.com/37191))

   * When MySQL was configured with the `--with-max-indexes=128' option,
     *Note `mysqld': mysqld. crashed.  (Bug#36751
     (http://bugs.mysql.com/36751))

   * The `event', `general_log', and `slow_log' tables in the `mysql'
     database store `server_id' values, but did not use an `UNSIGNED'
     column and thus were not able to store the full range of ID values.
     (Bug#36540 (http://bugs.mysql.com/36540))

   * Setting the `join_buffer_size' variable to its minimum value
     produced spurious warnings.  (Bug#36446
     (http://bugs.mysql.com/36446))

   * The audit plugin was not receiving `MYSQL_AUDIT_GENERAL_ERROR'
     events.  (Bug#36098 (http://bugs.mysql.com/36098))

   * The use of `NAME_CONST()' can result in a problem for `CREATE
     TABLE ...  SELECT' statements when the source column expressions
     refer to local variables. Converting these references to
     `NAME_CONST()' expressions can result in column names that are
     different on the master and slave servers, or names that are too
     long to be legal column identifiers. A workaround is to supply
     aliases for columns that refer to local variables.

     Now a warning is issued in such cases that indicate possible
     problems.  (Bug#35383 (http://bugs.mysql.com/35383))

   * *Note `SHOW CREATE EVENT': show-create-event. output did not
     include the `DEFINER' clause.  (Bug#35297
     (http://bugs.mysql.com/35297))

   * It was not possible to interrupt a long running *Note `BACKUP
     DATABASE': backup-database. or *Note `RESTORE': restore. operation.
     (Bug#35079 (http://bugs.mysql.com/35079))

   * Several deprecated or obsolete settings were removed from the
     sample option files.  (Bug#34521 (http://bugs.mysql.com/34521))

   * *Note `INSTALL PLUGIN': install-plugin. and *Note `UNINSTALL
     PLUGIN': uninstall-plugin. did not handle plugin identifiers
     consistently with respect to lettercase.  (Bug#33731
     (http://bugs.mysql.com/33731))

   * *Note `RESTORE': restore. often would not correctly identify the
     tablespace into which a `Falcon' table should be restored.
     (Bug#33569 (http://bugs.mysql.com/33569))

   * *Note `mysqldump --compatible=mysql40': mysqldump. emitted
     statements referring to the `character_set_client' system
     variable, which is unknown before MySQL 4.1. Now the statements
     are enclosed in version-specific comments.  (Bug#33550
     (http://bugs.mysql.com/33550))

   * The DDL blocker for *Note `BACKUP DATABASE': backup-database. and
     *Note `RESTORE': restore.  did not block all statements that it
     should. The blocker is now called the Backup Metadata Lock and
     blocks statements that change database metadata.  (Bug#32702
     (http://bugs.mysql.com/32702))

   * Detection by `configure' of several functions such as
     `setsockopt()', `bind()', `sched_yield()', and `gtty()' could fail.
     (Bug#31506 (http://bugs.mysql.com/31506))

   * Use of MBR spatial functions such as `MBRTouches()' with columns of
     `InnoDB' tables caused a server crash rather than an error.
     (Bug#31435 (http://bugs.mysql.com/31435))

   * When an `InnoDB' tablespace filled up, an error was logged to the
     client, but not to the error log. Also, the error message was
     misleading and did not indicate the real source of the problem.
     (Bug#31183 (http://bugs.mysql.com/31183))

   * The *Note `mysql': mysql. client mishandled input parsing if a
     `delimiter' command was not first on the line.  (Bug#31060
     (http://bugs.mysql.com/31060))

   * *Note `SHOW PRIVILEGES': show-privileges. listed the `CREATE
     ROUTINE' privilege as having a context of `Functions,Procedures',
     but it is a database-level privilege.  (Bug#30305
     (http://bugs.mysql.com/30305))

   * *Note `CHECK TABLE': check-table, *Note `REPAIR TABLE':
     repair-table, *Note `ANALYZE TABLE': analyze-table, and *Note
     `OPTIMIZE TABLE': optimize-table. erroneously reported a table to
     be corrupt if the table did not exist or the statement was
     terminated with *Note `KILL': kill.  (Bug#29458
     (http://bugs.mysql.com/29458))

   * For `InnoDB' tables that have their own `.ibd' tablespace file, a
     superfluous `ibuf cursor restoration fails!' message could be
     written to the error log. This warning has been suppressed.
     (Bug#27276 (http://bugs.mysql.com/27276))

   * Internal `base64_XXX()' functions were renamed to have a prefix of
     `my_' to avoid conflicts with other libraries.  (Bug#26818
     (http://bugs.mysql.com/26818))

   * The `Time' column for *Note `SHOW PROCESSLIST': show-processlist.
     output and the value of the `TIME' column of the *Note
     `INFORMATION_SCHEMA.PROCESSLIST': processlist-table.  table now
     can have negative values. Previously, the column was unsigned and
     negative values were displayed incorrectly as large positive
     values. Negative values can occur if a thread alters the time into
     the future with *Note `SET TIMESTAMP = VALUE': set-option. or the
     thread is executing on a slave and processing events from a master
     that has its clock set ahead of the slave.  (Bug#22047
     (http://bugs.mysql.com/22047))

   * Restoring a *Note `mysqldump': mysqldump. dump file containing
     `FEDERATED' tables failed because the file contained the data for
     the table. Now only the table definition is dumped (because the
     data is located elsewhere).  (Bug#21360
     (http://bugs.mysql.com/21360))

   * *Note `SHOW CREATE DATABASE': show-create-database. did not
     account for the value of the `lower_case_table_names' system
     variable.  (Bug#21317 (http://bugs.mysql.com/21317))

   * `ROUND()' sometimes returned different results on different
     platforms.  (Bug#15936 (http://bugs.mysql.com/15936))


File: manual.info,  Node: news-6-0-10,  Next: news-6-0-9,  Prev: news-6-0-11,  Up: news-6-0-x

C.1.2 Changes in MySQL 6.0.10 (03 March 2009)
---------------------------------------------

Functionality added or changed:

   * *Important Change*: *Replication*: *Note `RESET MASTER':
     reset-master. and *Note `RESET SLAVE': reset-slave. now reset the
     values shown for `Last_IO_Error', `Last_IO_Errno',
     `Last_SQL_Error', and `Last_SQL_Errno' in the output of *Note
     `SHOW SLAVE STATUS': show-slave-status.  (Bug#34654
     (http://bugs.mysql.com/34654))

   * *Replication*: A new global server variable `sync_relay_log' is
     introduced for use on replication slaves. Setting this variable to
     a nonzero integer value N causes the slave to synchonize the relay
     log to disk after every N events. Setting its value to 0 allows
     the operation system to handle syncronization of the file. The
     action of this variable, when enabled, is analogous to how the
     `sync_binlog' variable works with regard to binary logs on a
     replication master.

     This variable can also be set in `my.cnf', or by using the server
     option `--sync-relay-log'.

     For more information, see *Note replication-options-slave::.
     (Bug#31665 (http://bugs.mysql.com/31665), Bug#35542
     (http://bugs.mysql.com/35542), Bug#40337
     (http://bugs.mysql.com/40337))

   * *Replication*: In circular replication, it was sometimes possible
     for an event to propagate such that it would be reapplied on all
     servers.  This could occur when the originating server was removed
     from the replication circle and so could no longer act as the
     terminator of its own events, as normally happens in circular
     replication.

     In order to prevent this from occurring, a new `IGNORE_SERVER_IDS'
     option is introduced for the `CHANGE MASTER TO' statement. This
     option takes a list of replication server IDs; events having a
     server ID which appears in this list are ignored and not applied.
     For more information, see *Note change-master-to::.  (Bug#25998
     (http://bugs.mysql.com/25998)) See also Bug#27808
     (http://bugs.mysql.com/27808).

   * The `libedit' library was upgraded to version 2.11.  (Bug#42433
     (http://bugs.mysql.com/42433))

   * A new status variable, `Queries', indicates the number of
     statements executed by the server. This includes statements
     executed within stored programs, unlike the `Questions' variable
     which includes only statements sent to the server by clients.
     (Bug#41131 (http://bugs.mysql.com/41131))

   * Columns that provide a catalog value in `INFORMATION_SCHEMA'
     tables (for example, `TABLES.TABLE_CATALOG') now have a value of
     `def' rather than `NULL'.  (Bug#35427
     (http://bugs.mysql.com/35427))

   * `mysql-test-run.pl' now supports `--client-bindir' and
     `--client-libdir' options for specifying the directory where
     client binaries and libraries are located.  (Bug#34995
     (http://bugs.mysql.com/34995))

Bugs fixed:

   * *Security Fix*: Using an XPath expression employing a scalar
     expression as a FilterExpr
     (http://www.w3.org/TR/xpath#NT-FilterExpr) with `ExtractValue()' or
     `UpdateXML()' caused the server to crash. Such expressions now
     cause an error instead.  (Bug#42495 (http://bugs.mysql.com/42495))

   * *Incompatible Change*: The fix for Bug#33699
     (http://bugs.mysql.com/33699) introduced a change to the *Note
     `UPDATE': update. statement such that assigning `NULL' to a `NOT
     NULL' column caused an error even when strict SQL mode was not
     enabled. The original behavior before was that such assignments
     caused an error only in strict SQL mode, and otherwise set the
     column to the the implicit default value for the column data type
     and generated a warning. (For information about implicit default
     values, see *Note data-type-defaults::.)

     The change caused compatibility problems for applications that
     relied on the original behavior. It also caused replication
     problems between servers that had the original behavior and those
     that did not, for applications that assigned `NULL' to `NOT NULL'
     columns in *Note `UPDATE': update. statements without strict SQL
     mode enabled. This change has been reverted so that *Note
     `UPDATE': update. again had the original behavior. Problems can
     still occur if you replicate between servers that have the modified
     *Note `UPDATE': update. behavior and those that do not.
     (Bug#39265 (http://bugs.mysql.com/39265))

   * *Important Change*: *Replication*: If a trigger was defined on an
     `InnoDB' table and this trigger updated a non-transactional table,
     changes performed on the `InnoDB' table were replicated and were
     visible on the slave before they were committed on the master, and
     were not rolled back on the slave after a successful rollback of
     those changes on the master.

     As a result of the fix for this issue, the semantics of mixing
     non-transactional and transactional tables in a transaction in the
     first statement of a transaction have changed. Previously, if the
     first statement in a transaction contained non-transactional
     changes, the statement was written directly to the binary log.
     Now, any statement appearing after a *Note `BEGIN': commit. (or
     immediately following a *Note `COMMIT': commit. if `AUTOCOMMIT' =
     0) is always considered part of the transaction and cached. This
     means that non-transactional changes do not propagate to the slave
     until the transaction is committed and thus written to the binary
     log.

     See *Note replication-features-transactions::, for more
     information about this change in behavior.  (Bug#40116
     (http://bugs.mysql.com/40116))

   * *Important Change*: *Replication*: `MyISAM' transactions
     replicated to a transactional slave left the slave in an unstable
     condition.  This was due to the fact that, when replicating from a
     non-transactional storage engine to a transactional engine with
     `AUTOCOMMIT' turned off, no *Note `BEGIN': commit. and *Note
     `COMMIT': commit. statements were written to the binary log; thus,
     on the slave, a never-ending transaction was started.

     The fix for this issue includes enforcing `AUTOCOMMIT' mode on the
     slave by replicating all `AUTOCOMMIT=1' statements from the master.
     (Bug#29288 (http://bugs.mysql.com/29288))

   * *Partitioning*: A comparison with an invalid `DATE' value in a
     query against a partitioned table could lead to a crash of the
     MySQL server.

     *Note*:

     Invalid `DATE' and `DATETIME' values referenced in the `WHERE'
     clause of a query on a partitioned table are treated as `NULL'. See
     *Note partitioning-pruning::, for more information.

     (Bug#40972 (http://bugs.mysql.com/40972))

   * *Partitioning*: A query that timed out when run against a
     partitioned table failed silently, without providing any warnings
     or errors, rather than returning `Lock wait timeout exceeded'.
     (Bug#40515 (http://bugs.mysql.com/40515))

   * *Partitioning*: `ALTER TABLE ... REORGANIZE PARTITION' could crash
     the server when the number of partitions was not changed.
     (Bug#40389 (http://bugs.mysql.com/40389)) See also Bug#41945
     (http://bugs.mysql.com/41945).

   * *Partitioning*: `ALTER TABLE ... ADD PARTITION' and `ALTER TABLE
     ... DROP PARTITION' could cause the MySQL server to crash. This
     was only known to occur on Windows platforms where MySQL had been
     built with the `EXTRA_DEBUG' option.  (Bug#38784
     (http://bugs.mysql.com/38784))

   * *Partitioning*: `SHOW TABLE STATUS' could show a nonzero value for
     the `Mean record length' of a partitioned `InnoDB' table, even if
     the table contained no rows.  (Bug#36312
     (http://bugs.mysql.com/36312))

   * *Partitioning*: Several error messages relating to partitioned
     tables were incorrect or missing.  (Bug#36001
     (http://bugs.mysql.com/36001))

   * *Partitioning*: Unnecessary calls were made in the server code for
     performing bulk inserts on partitions for which no inserts needed
     to be made.  (Bug#35845 (http://bugs.mysql.com/35845)) See also
     Bug#35843 (http://bugs.mysql.com/35843).

   * *Partitioning*: For partitioned tables with more than ten
     partitions, a full table scan was used in some cases when only a
     subset of the partitions were needed.  (Bug#33730
     (http://bugs.mysql.com/33730))

   * *Replication*: On Windows, *Note `RESET MASTER': reset-master.
     failed in the event of a missing binlog file rather than issuing a
     warning and completing the rest of the statement.  (Bug#42150
     (http://bugs.mysql.com/42150), Bug#42288
     (http://bugs.mysql.com/42288))

   * *Replication*: Per-table `AUTO_INCREMENT' option values were not
     replicated correctly for `InnoDB' tables.  (Bug#41986
     (http://bugs.mysql.com/41986))

   * *Replication*: Some `log_event' types did not skip the post-header
     when reading.  (Bug#41961 (http://bugs.mysql.com/41961))

   * *Replication*: Attempting to read a binary log containing an
     `Incident_log_event' having an invalid incident number could cause
     the debug server to crash.  (Bug#40482
     (http://bugs.mysql.com/40482))

   * *Replication*: When *Note `CHANGE MASTER TO ... SET
     MASTER_HEARTBEAT_PERIOD ...': change-master-to. failed, no error
     code was set.  (Bug#40459 (http://bugs.mysql.com/40459))

   * *Replication*: When using row-based replication, an update of a
     primary key that was rolled back on the master due to a duplicate
     key error was not rolled back on the slave.  (Bug#40221
     (http://bugs.mysql.com/40221))

   * *Replication*: When rotating relay log files, the slave deletes
     relay log files and then edits the relay log index file. Formerly,
     if the slave shut down unexpectedly between these two events, the
     relay log index file could then reference relay logs that no longer
     existed. Depending on the circumstances, this could when
     restarting the slave cause either a race condition or the failure
     of replication.  (Bug#38826 (http://bugs.mysql.com/38826),
     Bug#39325 (http://bugs.mysql.com/39325))

   * *Replication*: *Note `START SLAVE UNTIL': start-slave. did not
     work correctly with `--replicate-same-server-id' enabled; when
     started with this option, the slave did not perform events
     recorded in the relay log and that originated from a different
     master.

     Log rotation events are automatically generated and written when
     rotating the binary log or relay log. Such events for relay logs
     are usually ignored by the slave SQL thread because they have the
     same server ID as that of the slave. However, when
     `--replicate-same-server-id' was enabled, the rotation event for
     the relay log was treated as if it originated on the master,
     because the log's name and position were incorrectly updated. This
     caused the `MASTER_POS_WAIT()' function always to return `NULL'
     and thus to fail.  (Bug#38734 (http://bugs.mysql.com/38734),
     Bug#38934 (http://bugs.mysql.com/38934))

   * *Replication*: A slave compiled using `--with-libevent' and run
     with `--thread-handling=pool-of-threads' could sometimes crash.
     (Bug#36929 (http://bugs.mysql.com/36929))

   * *Replication*: *Note `TRUNCATE': truncate. statements failed to
     replicate when statement-based binary logging mode was not
     available. The issue was observed when using `InnoDB' with the
     transaction isolation level set to `READ UNCOMMITTED' (thus
     forcing `InnoDB' not to allow statement-based logging). However,
     the same behavior could be reproduced using any transactional
     storage engine supporting only row-based logging, regardless of
     the isolation level. This was due to two separate problems:

       1. An error was printed by `InnoDB' for *Note `TRUNCATE':
          truncate. when using statement-based logging mode where the
          transaction isolation level was set to `READ COMMITTED' or
          `READ UNCOMMITTED', because `InnoDB' permits statement-based
          replication for DML statements. However, *Note `TRUNCATE':
          truncate. is not transactional; since it is the equivalent of
          `DROP TABLE' followed by *Note `CREATE TABLE': create-table,
          it is actually DDL, and should therefore be allowed to be
          replicated as a statement.

       2. *Note `TRUNCATE': truncate. was not logged in mixed mode
          because of the error just described; however, this error was
          not reported to the client.

     As a result of this fix, *Note `TRUNCATE': truncate.  is now
     treated as DDL for purposes of binary logging and replication;
     that is, it is always logged as a statement and so no longer
     causes an error when replicated using a transactional storage
     engine such as `InnoDB'.  (Bug#36763 (http://bugs.mysql.com/36763))
     See also Bug#42643 (http://bugs.mysql.com/42643).

   * *Replication*: *Note `mysqlbinlog': mysqlbinlog. replay of *Note
     `CREATE TEMPORARY TABLE ... LIKE': create-table. statements and of
     *Note `TRUNCATE': truncate. statements used on temporary tables
     failed with Error 1146 (`Table ...  doesn't exist').  (Bug#35583
     (http://bugs.mysql.com/35583))

   * *Replication*: *Note `mysqlbinlog': mysqlbinlog. sometimes failed
     when trying to create temporary files; this was because it ignored
     the specified temp file directory and tried to use the system
     `/tmp' directory instead.  (Bug#35546
     (http://bugs.mysql.com/35546)) See also Bug#35543
     (http://bugs.mysql.com/35543).

   * *Replication*: In statement mode, *Note `mysqlbinlog':
     mysqlbinlog. failed to issue a `SET @@autommit' statement when the
     autocommit mode was changed.  (Bug#34541
     (http://bugs.mysql.com/34541))

   * *Replication*: *Note `LOAD DATA INFILE': load-data. statements did
     not replicate correctly from a master running MySQL 4.1 to a slave
     running MySQL 5.1 or later.  (Bug#31240
     (http://bugs.mysql.com/31240))

   * *Replication*: The statements *Note `DROP PROCEDURE IF EXISTS':
     drop-procedure. and *Note `DROP FUNCTION IF EXISTS':
     drop-function. were not written to the binary log if the procedure
     or function to be dropped did not exist.  (Bug#13684
     (http://bugs.mysql.com/13684)) See also Bug#25705
     (http://bugs.mysql.com/25705).

   * The optimizer could underestimate the memory required for column
     descriptors during join processing and cause memory corruption or
     a server crash.  (Bug#42744 (http://bugs.mysql.com/42744))

   * A `'%'' character in SQL statements could cause the server to
     crash.  (Bug#42634 (http://bugs.mysql.com/42634))

   * For the batched-key access method, numbers of records were being
     specified rather than numbers of ranges.  (Bug#42593
     (http://bugs.mysql.com/42593))

   * Certain queries could result in Valgrind warnings in the optimizer.
     (Bug#42534 (http://bugs.mysql.com/42534))

   * An optimization introduced for Bug#37553
     (http://bugs.mysql.com/37553) required an explicit cast to be
     added for some uses of `TIMEDIFF()' because automatic casting
     could produce incorrect results. (It was necessary to use
     `TIME(TIMEDIFF(...))'.)  (Bug#42525 (http://bugs.mysql.com/42525))

   * On the IBM i5 platform, the MySQL configuration process caused the
     system version of `pthread_setschedprio()' to be used. This
     function returns `SIGILL' on i5 because it is not supported,
     causing the server to crash. Now the `my_pthread_setprio()'
     function in the `mysys' library is used instead.  (Bug#42524
     (http://bugs.mysql.com/42524))

   * The SSL certficates included with MySQL distributions were
     regenerated because the previous ones had expired.  (Bug#42366
     (http://bugs.mysql.com/42366))

   * User variables within triggers could cause a crash if the *Note
     `mysql_change_user()': mysql-change-user. C API function was
     invoked.  (Bug#42188 (http://bugs.mysql.com/42188))

   * Parsing of the optional microsecond component of *Note `DATETIME':
     datetime. values did not fail gracefully when that component width
     was larger than the allowed six places.  (Bug#42146
     (http://bugs.mysql.com/42146))

   * For `Falcon' tables, range queries using an index prefix were slow
     when Multi-Range Read index scans were disabled.  (Bug#42136
     (http://bugs.mysql.com/42136), Bug#41890
     (http://bugs.mysql.com/41890))

   * Dependent subqueries such as the following caused a memory leak
     proportional to the number of outer rows:

          SELECT COUNT(*) FROM t1, t2 WHERE t2.b
            IN (SELECT DISTINCT t2.b FROM t2 WHERE t2.b = t1.a);

     (Bug#42037 (http://bugs.mysql.com/42037))

   * Queries executed using a join buffer could return incorrect
     results.  (Bug#42020 (http://bugs.mysql.com/42020))

   * Some queries using `NAME_CONST(.. COLLATE ...)' led to a server
     crash due to a failed type cast.  (Bug#42014
     (http://bugs.mysql.com/42014))

   * The MAP file was not included in Windows distribution, but is
     needed by the `InnoDB' plugin. MAP file generation has again been
     enabled.  (Bug#42001 (http://bugs.mysql.com/42001))

   * The optimizer underestimated the number of field descriptors for
     the join buffer in some cases.  (Bug#41919
     (http://bugs.mysql.com/41919))

   * Internal misconfiguration of the hash table used for the join
     buffer could cause a server crash.  (Bug#41894
     (http://bugs.mysql.com/41894))

   * String reallocation could cause memory overruns.  (Bug#41868
     (http://bugs.mysql.com/41868))

   * Queries executed using semi-join materialization could cause a
     crash if the outer query has a `HAVING' clause.  (Bug#41842
     (http://bugs.mysql.com/41842))

   * A Valgrind warning in `open_tables()' was corrected.  (Bug#41759
     (http://bugs.mysql.com/41759))

   * A Valgrind warning in `setup_wild()' was corrected.  (Bug#41729
     (http://bugs.mysql.com/41729))

   * For `Falcon' tables, concurrent execution of a statement which in
     the general case should acquire a `TL_READ_NO_INSERT' lock on the
     table (for example multiple-table update, DML with subqueries, or
     statements involving new foreign key checks) and a statement that
     modifies the table might lead to warnings in the error log or even
     to deadlocks.  (Bug#41688 (http://bugs.mysql.com/41688), Bug#42069
     (http://bugs.mysql.com/42069))

   * Setting `innodb_locks_unsafe_for_binlog' should be equivalent to
     setting the transaction isolation level to `READ COMMITTED'.
     However, if both of those things were done, non-matching
     semi-consistently read rows were not unlocked when they should
     have been.  (Bug#41671 (http://bugs.mysql.com/41671))

   * *Note `resolve_stack_dump': resolve-stack-dump. was unable to
     resolve the stack trace format produced by *Note `mysqld': mysqld.
     in MySQL 5.1 and up (see *Note using-stack-trace::).  (Bug#41612
     (http://bugs.mysql.com/41612))

   * In example option files provided in MySQL distributions, the
     `thread_stack' value was increased from 64K to 128K.  (Bug#41577
     (http://bugs.mysql.com/41577))

   * *Note `REPAIR TABLE': repair-table. crashed for compressed
     `MyISAM' tables.  (Bug#41574 (http://bugs.mysql.com/41574))

   * The optimizer could ignore an error and rollback request during a
     filesort, causing an assertion failure.  (Bug#41543
     (http://bugs.mysql.com/41543))

   * `DATE_FORMAT()' could cause a server crash for year-zero dates.
     (Bug#41470 (http://bugs.mysql.com/41470))

   * *Note `BACKUP DATABASE': backup-database. and *Note `RESTORE':
     restore. did not reset the message list displayed by *Note `SHOW
     WARNINGS': show-warnings.  (Bug#41468
     (http://bugs.mysql.com/41468), Bug#41359
     (http://bugs.mysql.com/41359))

   * *Note `SET PASSWORD': set-password. caused a server crash if the
     account name was given as `CURRENT_USER()'.  (Bug#41456
     (http://bugs.mysql.com/41456))

   * When substituting system constant functions with a constant
     result, the server was not expecting `NULL' function return values
     and could crash.  (Bug#41437 (http://bugs.mysql.com/41437))

   * The `mysql-test/include/UnicodeData.txt' file, if present, was not
     included in MySQL distributions.  (Bug#41436
     (http://bugs.mysql.com/41436))

   * For a *Note `TIMESTAMP NOT NULL DEFAULT ...': datetime. column,
     storing `NULL' as the return value from some functions caused a
     `cannot be NULL' error.  `NULL' returns now correctly cause the
     column default value to be stored.  (Bug#41370
     (http://bugs.mysql.com/41370))

   * Queries such as `SELECT ... CASE AVG(...) WHEN ...' that used
     aggregate functions in a `CASE' expression crashed the server.
     (Bug#41363 (http://bugs.mysql.com/41363))

   * *Note `INSERT INTO .. SELECT ... FROM': insert. and *Note `CREATE
     TABLE ... SELECT ... FROM': create-table. a TEMPORARY table could
     inadvertently change the locking type of the temporary table from
     a write lock to a read lock, causing statement failure.
     (Bug#41348 (http://bugs.mysql.com/41348))

   * On Windows, the server could not be started with the
     `--thread-handling=pool-of-threads' option.  (Bug#41218
     (http://bugs.mysql.com/41218))

   * For a query that is executed using a range access method over an
     index that matches the ordering and there is an `ORDER BY' clause,
     *Note `EXPLAIN': explain.  showed `Using MRR' even though
     Multi-Range Read access was not used.  (Bug#41136
     (http://bugs.mysql.com/41136))

   * The server cannot execute *Note `INSERT DELAYED': insert.
     statements when statement-based binary logging is enabled, but the
     error message displayed only the table name, not the entire
     statement.  (Bug#41121 (http://bugs.mysql.com/41121))

   * `FULLTEXT' indexes did not work for Unicode columns that used a
     custom UCA collation.  (Bug#41084 (http://bugs.mysql.com/41084))

   * The *Note `INFORMATION_SCHEMA.SCHEMA_PRIVILEGES':
     schema-privileges-table.  table was limited to 7680 rows.
     (Bug#41079 (http://bugs.mysql.com/41079))

   * In debug builds, obsolete debug code could be used to crash the
     server.  (Bug#41041 (http://bugs.mysql.com/41041))

   * When a storage engine plugin failed to initialize before
     allocating a slot number, it would acidentally unplug the engine
     in slot 0.  (Bug#41013 (http://bugs.mysql.com/41013))

   * Some queries that used a `range checked for each record' scan
     could return incorrect results.  (Bug#40974
     (http://bugs.mysql.com/40974))

   * For `BACKUP DATABASE', errors from the commit blocker were not
     logged.  (Bug#40970 (http://bugs.mysql.com/40970))

   * Certain *Note `SELECT': select. queries could fail with a
     `Duplicate entry' error.  (Bug#40953 (http://bugs.mysql.com/40953))

   * For debug servers, *Note `OPTIMIZE TABLE': optimize-table.  on a
     compressed table caused a server crash.  (Bug#40949
     (http://bugs.mysql.com/40949))

   * The Windows installer displayed incorrect product names in some
     images.  (Bug#40845 (http://bugs.mysql.com/40845))

   * The CSV engine did not parse '\X' characters when they occurred in
     unquoted fields.  (Bug#40814 (http://bugs.mysql.com/40814))

   * Comparison of empty strings for the `latin2_czech_cs' character
     set could hang.  (Bug#40805 (http://bugs.mysql.com/40805))

   * `IF(..., CAST(LONGTEXT_VAL AS UNSIGNED), SIGNED_VAL)' as an
     argument to an aggregate function could cause an assertion failure.
     (Bug#40761 (http://bugs.mysql.com/40761))

   * Changing `innodb_thread_concurrency' at runtime could cause errors.
     (Bug#40760 (http://bugs.mysql.com/40760))

   * On Windows, starting the server with an invalid value for
     `innodb_flush_method' caused a crash.  (Bug#40757
     (http://bugs.mysql.com/40757))

   * When archive tables were joined on their primary keys, a query
     returned no result if the optimizer chose to use this index.
     (Bug#40677 (http://bugs.mysql.com/40677))

   * MySQL 5.1 crashed with index merge algorithm and merge tables.

     A query in the MyISAM merge table caused a crash if the index
     merge algorithm was being used.  (Bug#40675
     (http://bugs.mysql.com/40675))

   * `SELECT' statements could be blocked by *Note `INSERT DELAYED':
     insert.  statements that were waiting for a lock, even with
     `low_priority_updates' enabled.  (Bug#40536
     (http://bugs.mysql.com/40536))

   * If a *Note `RESTORE': restore. operation was in progress on a
     master server, slaves were not prohibited from starting
     replication of the master.  (Bug#40434
     (http://bugs.mysql.com/40434))

   * *Note `TRUNCATE TABLE': truncate. for an `InnoDB' table did not
     flush cached queries for the table.  (Bug#40386
     (http://bugs.mysql.com/40386))

   * For `InnoDB' tables that used `ROW_FORMAT=REDUNDANT', storage size
     of `NULL' columns could be determined incorrectly.  (Bug#40369
     (http://bugs.mysql.com/40369))

   * `Backup completed' was logged for non-successful *Note `BACKUP
     DATABASE': backup-database. operations.  `Restore completed' was
     logged for non-successful *Note `RESTORE': restore. operations.
     (Bug#40305 (http://bugs.mysql.com/40305))

   * The query cache stored only partial query results if a statement
     failed while the results were being sent to the client. This could
     cause other clients to hang when trying to read the cached result.
     Now if a statement fails, the result is not cached.  (Bug#40264
     (http://bugs.mysql.com/40264))

   * The `':'' character was incorrectly disallowed in table names.
     (Bug#40104 (http://bugs.mysql.com/40104))

   * For an `InnoDB' table, *Note `DROP TABLE': drop-table. or *Note
     `ALTER TABLE ... DISCARD TABLESPACE': alter-table. could take a
     long time or cause a server crash.  (Bug#39939
     (http://bugs.mysql.com/39939))

   * Threads were set to the `Table lock' state in such a way that use
     of this state by other threads to check for a lock wait was
     subject to a race condition.  (Bug#39897
     (http://bugs.mysql.com/39897))

   * When a `MEMORY' table became full, the error generated was
     returned to the client but was not written to the error log.
     (Bug#39886 (http://bugs.mysql.com/39886))

   * For a server started with the `--temp-pool' option on Windows,
     temporary file creation could fail. This option now is ignored
     except on Linux systems, which was its original intended scope.
     (Bug#39750 (http://bugs.mysql.com/39750))

   * The implementation of the `backup_wait_timeout' system variable
     was machine dependent and did not work correctly on big-endian
     machines.  (Bug#39749 (http://bugs.mysql.com/39749), Bug#40808
     (http://bugs.mysql.com/40808))

   * *Note `ALTER TABLE': alter-table. on a table with `FULLTEXT' index
     that used a pluggable `FULLTEXT' parser could cause debug servers
     to crash.  (Bug#39746 (http://bugs.mysql.com/39746))

   * The server crashed if an integer field in a CSV file did not have
     delimiting quotes.  (Bug#39616 (http://bugs.mysql.com/39616))

   * `InnoDB' could hang trying to open an adaptive hash index.
     (Bug#39483 (http://bugs.mysql.com/39483))

   * Queries with that end with `... WHERE CONDITION ORDER BY
     INDEX_COLUMNS LIMIT N' could produce rows that did not match the
     `WHERE' clause for certain kinds of conditions and table data
     distributions.  (Bug#39447 (http://bugs.mysql.com/39447))

   * The internal buffering logic for *Note `BACKUP DATABASE':
     backup-database. had a problem that could lead to corrupt backup
     images.  (Bug#39375 (http://bugs.mysql.com/39375))

   * A bad pointer dereference caused *Note `BACKUP DATABASE':
     backup-database. to crash.  (Bug#39361
     (http://bugs.mysql.com/39361))

   * `INFORMATION_SCHEMA' access optimizations did not work properly in
     some cases.  (Bug#39270 (http://bugs.mysql.com/39270))

   * Cardinality for merge tables kept approaching zero in
     `myrg_attach_children()' because `m_info->rec_per_key_part' was
     initialized to 0 only when the function was first called.
     (Bug#39185 (http://bugs.mysql.com/39185))

   * The expression `ROW(...) IN (SELECT ... FROM DUAL)' always
     returned `TRUE'.  (Bug#39069 (http://bugs.mysql.com/39069))

   * `SELECT * FROM INFORMATION_SCHEMA.ROUTINES' could fail if there
     was no default database.  (Bug#38916 (http://bugs.mysql.com/38916))

   * `InnoDB' could fail to generate `AUTO_INCREMENT' values after an
     *Note `UPDATE': update. statement for the table.  (Bug#38839
     (http://bugs.mysql.com/38839))

   * The greedy optimizer could cause a server crash due to improper
     handling of nested outer joins.  (Bug#38795
     (http://bugs.mysql.com/38795))

   * Use of `COUNT(DISTINCT)' prevented `NULL' testing in the `HAVING'
     clause.  (Bug#38637 (http://bugs.mysql.com/38637))

   * Building MySQL on FreeBSD would result in a failure during the
     `gen_lex_hash' phase of the build.  (Bug#38364
     (http://bugs.mysql.com/38364))

   * A mix of *Note `TRUNCATE TABLE': truncate. with *Note `LOCK
     TABLES': lock-tables.  and *Note `UNLOCK TABLES': lock-tables. for
     an `InnoDB' could cause a server crash.  (Bug#38231
     (http://bugs.mysql.com/38231))

   * The `ExtractValue()' function did not work correctly with XML
     documents containing a `DOCTYPE' declaration.  (Bug#38227
     (http://bugs.mysql.com/38227))

   * The `innodb_stats_on_metadata' system variable was not displayed
     by *Note `SHOW VARIABLES': show-variables. and was not settable at
     runtime.  (Bug#38189 (http://bugs.mysql.com/38189))

   * Enabling the `sync_frm' system variable had no effect on the
     handling of `.frm' files for views.  (Bug#38145
     (http://bugs.mysql.com/38145))

   * Use of spatial data types in prepared statements could cause
     memory leaks or server crashes.  (Bug#37956
     (http://bugs.mysql.com/37956), Bug#37671
     (http://bugs.mysql.com/37671))

   * An error in a debugging check caused crashes in debug servers.
     (Bug#37936 (http://bugs.mysql.com/37936))

   * An initialization procedure for materialized subquery execution
     was not called due to an early optimization of `MIN()'/`MAX()'
     queries.  (Bug#37896 (http://bugs.mysql.com/37896))

   * The presence of a `/* ... */' comment preceding a query could
     cause `InnoDB' to use unnecessary gap locks.  (Bug#37885
     (http://bugs.mysql.com/37885))

   * An assertion failure could occur when trying to execute a query
     with a subquery such that one of the subquery's tables was
     accessed using the DS-MRR access method.  (Bug#37842
     (http://bugs.mysql.com/37842))

   * For comparison of `NULL' to a subquery result inside `IS NULL',
     the comparison could evaluate to `NULL' rather than to `TRUE' or
     `FALSE'. This occurred for expressions such as:

          SELECT ... WHERE NULL IN (SELECT ...) IS NULL

     (Bug#37822 (http://bugs.mysql.com/37822))

   * Setting `myisam_repair_threads' greater than 1 caused a server
     crash for table repair or alteration operations for `MyISAM'
     tables with multiple `FULLTEXT' indexes.  (Bug#37756
     (http://bugs.mysql.com/37756))

   * Primary keys were treated as part of a covering index even if only
     a prefix of a key column was used.  (Bug#37742
     (http://bugs.mysql.com/37742))

   * The `MONTHNAME()' and `DAYNAME()' functions returned a binary
     string, so that using `LOWER()' or `UPPER()' had no effect. Now
     `MONTHNAME()' and `DAYNAME()' return a value in
     `character_set_connection' character set.  (Bug#37575
     (http://bugs.mysql.com/37575))

   * The internal-use-only `filename' character set was visible in the
     output of some `SHOW' statements and in the contents of the *Note
     `COLLATION_CHARACTER_SET_APPLICABILITY':
     collation-character-set-applicability-table.  table of
     `INFORMATION_SCHEMA'.  (Bug#37554 (http://bugs.mysql.com/37554))

   * Certain boolean-mode `FULLTEXT' searches that used the truncation
     operator did not return matching records and calculated relevance
     incorrectly.  (Bug#37245 (http://bugs.mysql.com/37245))

   * For an `InnoDB' table with a `FOREIGN KEY' constraint, `TRUNCATE
     TABLE' may be performed using row by row deletion. If an error
     occurred during this deletion, the table would be only partially
     emptied.  Now if an error occurs, the truncation operation is
     rolled back and the table is left unchanged.  (Bug#37016
     (http://bugs.mysql.com/37016))

   * Subquery materialization produced incorrect results when comparing
     different types.  (Bug#36752 (http://bugs.mysql.com/36752))

   * An argument to the `MATCH()' function that was an alias for an
     expression other than a column name caused a server crash.
     (Bug#36737 (http://bugs.mysql.com/36737))

   * Previously, statements inside a stored program did not clear the
     warning list. For example, warnings or errors generated by
     statements within a trigger or stored function would be
     accumulated and added to the message list for the statement that
     activated the trigger or invoked the function, `polluting' the
     output of *Note `SHOW WARNINGS': show-warnings. or *Note `SHOW
     ERRORS': show-errors.  for the outer statement. Normally, messages
     for a statement that can generate messages replace messages from
     the previous such statement. The effect was that a statement could
     have a different effect on the message list depending on whether it
     executed inside or outside of a stored program.

     Now within a stored program, successive statements that can
     generate messages update the message list and replace messages
     from the previous such statement. Only messages from the last of
     these statements is copied to the message list for the outer
     statement.  (Bug#36649 (http://bugs.mysql.com/36649))

   * *Note `myisampack --join': myisampack. did not create the
     destination table `.frm' file.  (Bug#36573
     (http://bugs.mysql.com/36573))

   * When parsing or formatting interval values of `DAY_MICROSECOND'
     type, fractional seconds were not handled correctly when
     more-significant fields were implied or omitted.  (Bug#36466
     (http://bugs.mysql.com/36466))

   * *Note `comp_err': comp-err. sometimes crashed due to improper
     mutex use.  (Bug#36428 (http://bugs.mysql.com/36428))

   * The *Note `mysql': mysql. client sometimes improperly interpreted
     string escape sequences in non-string contexts.  (Bug#36391
     (http://bugs.mysql.com/36391))

   * The query cache stored packets containing the server status of the
     time when the cached statement was run. This might lead to an
     incorrect transaction status on the client side if a statement was
     cached during a transaction and later served outside a transaction
     context (or vice versa).  (Bug#36326 (http://bugs.mysql.com/36326))

   * Some error numbers were incorrect.  (Bug#36062
     (http://bugs.mysql.com/36062))

   * For upgrades to MySQL 5.1 or higher, *Note `mysql_upgrade':
     mysql-upgrade. did not re-encode database or table names that
     contained non-alphanumeric characters. (They would still appear
     after the upgrade with the `#mysql50#' prefix described in *Note
     identifier-mapping::.) To correct this problem, it was necessary
     to run *Note `mysqlcheck --all-databases --check-upgrade
     --fix-db-names --fix-table-names': mysqlcheck.  manually. *Note
     `mysql_upgrade': mysql-upgrade. now runs that command
     automatically after performing the initial upgrade.  (Bug#35934
     (http://bugs.mysql.com/35934))

   * *Note `SHOW CREATE TABLE': show-create-table. did not display a
     printable value for the default value of *Note `BIT':
     numeric-types. columns.  (Bug#35796 (http://bugs.mysql.com/35796))

   * The `max_length' metadata value was calculated incorrectly for the
     `FORMAT()' function, which could cause incorrect result set
     metadata to be sent to clients.  (Bug#35558
     (http://bugs.mysql.com/35558))

   * `InnoDB' could fail to generate `AUTO_INCREMENT' values if rows
     previously had been inserted containing literal values for the
     `AUTO_INCREMENT' column.  (Bug#35498
     (http://bugs.mysql.com/35498), Bug#36411
     (http://bugs.mysql.com/36411), Bug#39830
     (http://bugs.mysql.com/39830))

   * Result set metadata for columns retrieved from
     `INFORMATION_SCHEMA' tables did not have the `db' or `org_table'
     members of the `MYSQL_FIELD' structure set.  (Bug#35428
     (http://bugs.mysql.com/35428))

   * If the system time was adjusted backward during query execution,
     the apparent execution time could be negative. But in some cases
     these queries would be written to the slow query log, with the
     negative execution time written as a large unsigned number. Now
     statements with apparent negative execution time are not written
     to the slow query log.  (Bug#35396 (http://bugs.mysql.com/35396))

   * The `CREATE_OPTIONS' column for *Note `INFORMATION_SCHEMA.TABLES':
     tables-table. did not display the `KEY_BLOCK_SIZE' option.
     (Bug#35275 (http://bugs.mysql.com/35275))

   * On Windows, the `_PC' macro in `my_global.h' was causing problems
     for modern compilers. It has been removed because it is no longer
     used.  (Bug#34309 (http://bugs.mysql.com/34309))

   * For *Note `DROP FUNCTION': drop-function. with names that were
     qualified with a database name, the database name was handled in
     case-sensitive fashion even with `lower_case_table_names' set to 1.
     (Bug#33813 (http://bugs.mysql.com/33813))

   * The *Note `mysql': mysql. client incorrectly parsed statements
     containing the word `delimiter' in mid-statement.  (Bug#33812
     (http://bugs.mysql.com/33812)) See also Bug#38158
     (http://bugs.mysql.com/38158).

   * Three conditions were discovered that could cause an upgrade from
     MySQL 5.0 to 5.1 to fail: 1) Triggers associated with a table that
     had a `#mysql50#' prefix in the name could cause assertion
     failure. 2) *Note `ALTER DATABASE ... UPGRADE DATA DIRECTORY
     NAME': alter-database. failed for databases that had a `#mysql50#'
     prefix if there were triggers in the database. 3) *Note
     `mysqlcheck --fix-table-name': mysqlcheck. didn't use UTF8 as the
     default character set, resulting in parsing errors for tables with
     non-latin symbols in their names and trigger definitions.
     (Bug#33094 (http://bugs.mysql.com/33094), Bug#41385
     (http://bugs.mysql.com/41385))

   * `libmysqld' was not built with all character sets.  (Bug#32831
     (http://bugs.mysql.com/32831))

   * Queries with dependent subqueries were slow.  (Bug#32665
     (http://bugs.mysql.com/32665))

   * For *Note `mysqld_multi': mysqld-multi, using the
     `--mysqld=mysqld_safe' option caused the `--defaults-file' and
     `--defaults-extra-file' options to behave the same way.
     (Bug#32136 (http://bugs.mysql.com/32136))

   * Attempts to open a valid MERGE table sometimes resulted in a
     `ER_WRONG_MRG_TABLE' error. This happened after failure to open an
     invalid MERGE table had also generated an `ER_WRONG_MRG_TABLE'
     error.  (Bug#32047 (http://bugs.mysql.com/32047))

   * Queries executed using join buffering of *Note `BIT':
     numeric-types. columns could produce incorrect results.
     (Bug#31399 (http://bugs.mysql.com/31399))

   * `ALTER TABLE CONVERT TO CHARACTER SET' did not convert *Note
     `TINYTEXT': blob. or *Note `MEDIUMTEXT': blob. columns to a longer
     text type if necessary when converting the column to a different
     character set.  (Bug#31291 (http://bugs.mysql.com/31291))

   * Server variables could not be set to their current values on Linux
     platforms. (These fixes are in addition to those made in MySQL
     6.0.5 and 6.0.9.)  (Bug#31177 (http://bugs.mysql.com/31177)) See
     also Bug#6958 (http://bugs.mysql.com/6958).

   * *Note `ALTER TABLE': alter-table. statements that added a column
     and added a non-partial index on the column failed to add the
     index.  (Bug#31031 (http://bugs.mysql.com/31031))

   * *Note `mysqld --help': mysqld. did not work as `root'.  (Bug#30261
     (http://bugs.mysql.com/30261))

   * Static storage engines and plugins that were disabled and dynamic
     plugins that were installed but disabled were not listed in the
     `INFORMATION_SCHEMA' appropriate *Note `PLUGINS': plugins-table. or
     *Note `ENGINES': engines-table. table.  (Bug#29263
     (http://bugs.mysql.com/29263))

   * On Windows, Visual Studio does not take into account some x86
     hardware limitations, which led to incorrect results converting
     large *Note `DOUBLE': numeric-types. values to unsigned *Note
     `BIGINT': numeric-types. values.  (Bug#27483
     (http://bugs.mysql.com/27483))

   * If the default database was dropped, the value of
     `character_set_database' was not reset to `character_set_server'
     as it should have been.  (Bug#27208 (http://bugs.mysql.com/27208))

   * SSL support was not included in some `generic' RPM packages.
     (Bug#26760 (http://bugs.mysql.com/26760))

   * *Note `SHOW TABLE STATUS': show-table-status. could fail to
     produce output for tables with non-ASCII characters in their name.
     (Bug#25830 (http://bugs.mysql.com/25830))

   * *Note `DROP TABLE': drop-table. for `INFORMATION_SCHEMA' tables
     produced an `Unknown table' error rather than the more appropriate
     `Access denied'.  (Bug#24062 (http://bugs.mysql.com/24062))

   * Allocation of stack space for error messages could be too small on
     HP-UX, leading to stack overflow crashes.  (Bug#21476
     (http://bugs.mysql.com/21476))

   * For the `DIV' operator, incorrect results could occur for
     non-integer operands that exceed *Note `BIGINT': numeric-types.
     range. Now, if either operand has a non-integer type, the operands
     are converted to *Note `DECIMAL': numeric-types. and divided using
     *Note `DECIMAL': numeric-types. arithmetic before converting the
     result to *Note `BIGINT': numeric-types.  If the result exceeds
     `BIGINT' range, an error occurs.  (Bug#8457
     (http://bugs.mysql.com/8457))


File: manual.info,  Node: news-6-0-9,  Next: news-6-0-8,  Prev: news-6-0-10,  Up: news-6-0-x

C.1.3 Changes in MySQL 6.0.9 (10 January 2009)
----------------------------------------------

Functionality added or changed:

   * *Note `BACKUP DATABASE': backup-database. and *Note `RESTORE':
     restore. now indicate in the server's error log which databases
     are being backed up or restored.  (Bug#40307
     (http://bugs.mysql.com/40307))

   * Performance of `SELECT *' retrievals from *Note
     `INFORMATION_SCHEMA.COLUMNS': columns-table. was improved slightly.
     (Bug#38918 (http://bugs.mysql.com/38918))

   * Previously, index hints did not work for `FULLTEXT' searches. Now
     they work as follows:

     For natural language mode searches, index hints are silently
     ignored. For example, `IGNORE INDEX(i)' is ignored with no warning
     and the index is still used.

     For boolean mode searches, index hints with `FOR ORDER BY' or `FOR
     GROUP BY' are silently ignored. Index hints with `FOR JOIN' or no
     `FOR' modifier are honored. In contrast to how hints apply for
     non-`FULLTEXT' searches, the hint is used for all phases of query
     execution (finding rows and retrieval, grouping, and ordering).
     This is true even if the hint is given for a non-`FULLTEXT' index.
     (Bug#38842 (http://bugs.mysql.com/38842))

   * MySQL support for adding collations using LDML specifications did
     not support the `<i>' identity rule that indicates one character
     sorts identically to another. The `<i>' rule now is supported.
     (Bug#37129 (http://bugs.mysql.com/37129))

   * Previously, *Note `RESTORE': restore. overwrote any databases with
     information from the backup image. Now, *Note `RESTORE': restore.
     aborts with an error if the backup image contains any databases
     that currently exist on the server, unless the optional keyword
     `OVERWRITE' is given following the image file name.  (Bug#34579
     (http://bugs.mysql.com/34579))

   * A new statement, `PURGE BACKUP LOGS', enables the contents of the
     MySQL Backup logs to be culled. See *Note purge-backup-logs::.
     (Bug#33364 (http://bugs.mysql.com/33364))

   * A new algorithm that uses both index access to the joined table
     and a join buffer has been implemented. It is called the Batched
     Key Access (BKA) Join algorithm. The algorithm supports inner
     join, outer join and semi-join operations, including nested outer
     joins and nested semi-joins. Also, the Block Nested-Loop (BNL)
     Join algorithm previously used only for inner joins has been
     extended and can be employed for outer join and semi-join
     operations, including nested nested outer joins and nested
     semi-joins. For more information, see *Note bnl-bka-optimization::.

     In conjunction with this work, there is a new system variable,
     `join_cache_level', that controls how join buffering is done.

Bugs fixed:

   * *Security Enhancement*: When the `DATA DIRECTORY' or `INDEX
     DIRECTORY' clause of a *Note `CREATE TABLE': create-table.
     statement referred to a subdirectory of the data directory via a
     symlinked component of the data directory path, it was accepted,
     when for security reasons it should be rejected.  (Bug#39277
     (http://bugs.mysql.com/39277))

   * *Incompatible Change*: *Note `CHECK TABLE ... FOR UPGRADE':
     check-table. did not check for collation changes made in MySQL
     6.0.1 to `latin2_czech_cs' (Bug#25420
     (http://bugs.mysql.com/25420)) or collation changes made in MySQL
     6.0.6 to `big5_chinese_ci', `cp866_general_ci',
     `gb2312_chinese_ci', and `gbk_chinese_ci'. This also affects *Note
     `mysqlcheck': mysqlcheck. and *Note `mysql_upgrade':
     mysql-upgrade, which cause that statement to be executed. See
     *Note checking-index-changes::.  (Bug#40054
     (http://bugs.mysql.com/40054))

   * *Partitioning*: *Replication*: Changing the transaction isolation
     level while replicating partitioned `InnoDB' tables could cause
     statement-based logging to fail.  (Bug#39084
     (http://bugs.mysql.com/39084))

   * *Partitioning*: This bug was introduced in MySQL 6.0.5.
     (Bug#40954 (http://bugs.mysql.com/40954)) This regression was
     introduced by Bug#30573 (http://bugs.mysql.com/30573), Bug#33257
     (http://bugs.mysql.com/33257), Bug#33555
     (http://bugs.mysql.com/33555).

   * *Partitioning*: With `READ COMMITTED' transaction isolation level,
     `InnoDB' uses a semi-consistent read that releases non-matching
     rows after MySQL has evaluated the `WHERE' clause.  However, this
     was not happening if the table used partitions.  (Bug#40595
     (http://bugs.mysql.com/40595))

   * *Partitioning*: A `SELECT' using a range `WHERE' condition with an
     `ORDER BY' on a partitioned table caused a server crash.
     (Bug#40494 (http://bugs.mysql.com/40494))

   * *Partitioning*: For a partitioned table having an `AUTO_INCREMENT'
     column: If the first statement following a start of the server or
     a `FLUSH TABLES' statement was an `UPDATE' statement, the
     `AUTO_INCREMENT' column was not incremented correctly.  (Bug#40176
     (http://bugs.mysql.com/40176))

   * *Partitioning*: The server attempted to execute the statements
     `ALTER TABLE ... ANALYZE PARTITION', `ALTER TABLE ...  CHECK
     PARTITION', `ALTER TABLE ... OPTIMIZE PARTITION', and `ALTER TABLE
     ... REORGANIZE PARTITION' on tables that were not partitioned.
     (Bug#39434 (http://bugs.mysql.com/39434)) See also Bug#20129
     (http://bugs.mysql.com/20129).

   * *Partitioning*: The value of the `CREATE_COLUMNS' column in *Note
     `INFORMATION_SCHEMA.TABLES': tables-table. was not `partitioned'
     for partitioned tables.  (Bug#38909 (http://bugs.mysql.com/38909))

   * *Partitioning*: When executing an `ORDER BY' query on a
     partitioned `InnoDB' table using an index that was not in the
     partition expression, the results were sorted on a per-partition
     basis rather than for the table as a whole.  (Bug#37721
     (http://bugs.mysql.com/37721))

   * *Partitioning*: Partitioned table checking sometimes returned a
     warning with an error code of 0, making proper response to errors
     impossible.  The fix also renders the error message subject to
     translation in non-English deployments.  (Bug#36768
     (http://bugs.mysql.com/36768))

   * *Partitioning*: When `SHOW CREATE TABLE' was used on a partitioned
     table, all of the table's `PARTITION' and `SUBPARTITION' clauses
     were output on a single line, making it difficult to read or parse.
     (Bug#14326 (http://bugs.mysql.com/14326))

   * *Replication*: Row-based replication failed with non-partitioned
     `MyISAM' tables having no indexes.  (Bug#40004
     (http://bugs.mysql.com/40004))

   * An assertion failure occurred for a join query when a small size
     of the join buffer was set and the value of `record_per_key' for
     the index used for a `ref' access with this join buffer was big
     enough.  (Bug#41204 (http://bugs.mysql.com/41204))

   * Unique indexes on `FALCON' tables can not be created when the the
     column is `NOT NULL'.  (Bug#40994 (http://bugs.mysql.com/40994))

   * Accessing user variables within triggers could cause a server
     crash.  (Bug#40770 (http://bugs.mysql.com/40770))

   * For single-table *Note `UPDATE': update.  statements, an assertion
     failure resulted from a runtime error in a stored function (such
     as a recursive function call or an attempt to update the same
     table as in the *Note `UPDATE': update. statement).  (Bug#40745
     (http://bugs.mysql.com/40745))

   * Date values of `000-00-00' inserted into a `FALCON' table were
     incorrectly recognized and returned when performing a `SELECT' on
     a field with an index.  (Bug#40614 (http://bugs.mysql.com/40614))

   * Several MySQL Backup-related memory-use issues identified by
     Valgrind were corrected.  (Bug#40480 (http://bugs.mysql.com/40480))

   * When executing concurrent `CREATE TABLE ...  SELECT' statements on
     a `Maria' table, the error `Error: Memory allocated at
     trnman.c:129 was underrun, discovered at ma_close.c:65' error
     would be logged in the error file, and the server would eventually
     crash.  (Bug#40416 (http://bugs.mysql.com/40416))

   * Prepared statements allowed invalid dates to be inserted when the
     `ALLOW_INVALID_DATES' SQL mode was not enabled.  (Bug#40365
     (http://bugs.mysql.com/40365))

   * With statement-based binary logging format and a transaction
     isolation level of `READ COMMITTED' or stricter, `InnoDB' printed
     an error because statement-based logging might lead to
     inconsistency between master and slave databases. However, this
     error was printed even when binary logging was not enabled (in
     which case, no such inconsistency can occur).  (Bug#40360
     (http://bugs.mysql.com/40360))

   * A query with an outer join where the `ON' expression evaluated to
     the constant `FALSE' could return incorrect results when a join
     buffer was used for the outer join operation.  (Bug#40317
     (http://bugs.mysql.com/40317))

   * Errors from a *Note `BACKUP DATABASE': backup-database. or *Note
     `RESTORE': restore. operation were shown by *Note `SHOW WARNINGS':
     show-warnings. as warnings, not errors.  (Bug#40304
     (http://bugs.mysql.com/40304))

   * If several errors occurred during a *Note `BACKUP DATABASE':
     backup-database. or *Note `RESTORE': restore.  operation, the
     final error was returned to the client, even though the first
     error is usually more pertinent.  (Bug#40303
     (http://bugs.mysql.com/40303))

   * Creation of a tablespace file within `FALCON' could create a
     tablespace entry in the `INFORMATION_SCHEMA.FALCON_TABLESPACE_IO'
     even the underlying data file had not been created.  (Bug#40302
     (http://bugs.mysql.com/40302))

   * Specifying the `--log-backup-output' option without an argument
     set the destination for the backup logs to `FILE' rather than to
     the default of `TABLE'.  (Bug#40282 (http://bugs.mysql.com/40282))

   * `mc.exe' is no longer needed to compile MySQL on Windows. This
     makes it possible to build MySQL from source using Visual Studio
     Express 2008.  (Bug#40280 (http://bugs.mysql.com/40280))

   * The server could generate extra rows in the result set for a query
     with a nested outer join if the inner tables of the outer join
     were joined using join buffers.  (Bug#40268
     (http://bugs.mysql.com/40268))

   * If *Note `BACKUP DATABASE': backup-database. was used to back up
     an empty database and binary logging enabled, the backup image was
     flagged as containing binary log information even though it did
     not. Using *Note `RESTORE': restore.  with the backup image then
     crashed trying to parse the binary log file name.  (Bug#40262
     (http://bugs.mysql.com/40262))

   * The `backup_history_log_file' and `backup_progress_log_file' system
     variables were not settable at server startup. Now they are.
     (Bug#40219 (http://bugs.mysql.com/40219))

   * The default value of the `backup_history_log' and
     `backup_progress_log' system variables is `ON', but explicitly
     setting them to `DEFAULT' set them to `OFF'.  (Bug#40218
     (http://bugs.mysql.com/40218))

   * When an outer join employed a join buffer to join the first inner
     table by the Blocked Nested-Loop algorithm, extra
     `NULL'-complemented rows could be generated if the `WHERE' clause
     contained conditions that can be pushed down to this table.
     (Bug#40192 (http://bugs.mysql.com/40192))

   * When the optimizer joined an inner table of an outer join using
     both `not exists' optimization and a join buffer, an incorrect
     result set could be returned.  (Bug#40134
     (http://bugs.mysql.com/40134))

   * Support for the `revision' field in `.frm' files has been removed.
     This addresses the downgrading problem introduced by the fix for
     Bug#17823 (http://bugs.mysql.com/17823).  (Bug#40021
     (http://bugs.mysql.com/40021))

   * The MySQL Backup message logger caused an assertion failure.
     (Bug#39997 (http://bugs.mysql.com/39997))

   * Retrieval speed from the following `INFORMATION_SCHEMA' tables was
     improved by shortening the `VARIABLE_VALUE' column to 1024
     characters: *Note `GLOBAL_VARIABLES': variables-table, *Note
     `SESSION_VARIABLES': variables-table, *Note `GLOBAL_STATUS':
     status-table, and *Note `SESSION_STATUS': status-table.

     As a result of this change, any variable value longer than 1024
     characters will be truncated with a warning. This affects only the
     `init_connect' system variable.  (Bug#39955
     (http://bugs.mysql.com/39955))

   * If the operating system is configured to return leap seconds from
     OS time calls or if the MySQL server uses a time zone definition
     that has leap seconds, functions such as `NOW()' could return a
     value having a time part that ends with `:59:60' or `:59:61'. If
     such values are inserted into a table, they would be dumped as is
     by *Note `mysqldump': mysqldump. but considered invalid when
     reloaded, leading to backup/restore problems.

     Now leap second values are returned with a time part that ends
     with `:59:59'. This means that a function such as `NOW()' can
     return the same value for two or three consecutive seconds during
     the leap second. It remains true that literal temporal values
     having a time part that ends with `:59:60' or `:59:61' are
     considered invalid.

     For additional details about leap-second handling, see *Note
     time-zone-leap-seconds::.  (Bug#39920
     (http://bugs.mysql.com/39920))

   * The server could crash during a sort-order optimization of a
     dependent subquery.  (Bug#39844 (http://bugs.mysql.com/39844))

   * Recovery of a tablespace for `FALCON' tables could fail if the
     tablespace was already in use.  (Bug#39789
     (http://bugs.mysql.com/39789))

   * Creating a `FALCON' table while specifying a specific tablespace
     and partition to be used for the table will fail if the specified
     tablespace does not already exist, returning a error indicating
     general table creation failure. The message has been updated to
     indicate that the failure is due to non-existent tablespace.
     (Bug#39702 (http://bugs.mysql.com/39702))

   * With the `ONLY_FULL_GROUP_BY' SQL mode enabled, the check for
     non-aggregated columns in queries with aggregate functions, but
     without a `GROUP BY' clause was treating all the parts of the
     query as if they were in the select list. This is fixed by
     ignoring the non-aggregated columns in the `WHERE' clause.
     (Bug#39656 (http://bugs.mysql.com/39656))

   * Concurrent execution of *Note `BACKUP DATABASE': backup-database.
     and DML operations on `MyISAM' tables could produce a deadlock.
     (Bug#39602 (http://bugs.mysql.com/39602))

   * The `do_abi_check' program run during the build process depends on
     `mysql_version.h' but that file was not created first, resulting
     in build failure.  (Bug#39571 (http://bugs.mysql.com/39571))

   * *Note `CHECK TABLE': check-table. failed for `MyISAM'
     `INFORMATION_SCHEMA' tables.  (Bug#39541
     (http://bugs.mysql.com/39541))

   * On 64-bit Windows systems, the server accepted `key_buffer_size'
     values larger than 4GB, but allocated less. (For example,
     specifying a value of 5GB resulted in 1GB being allocated.)
     (Bug#39494 (http://bugs.mysql.com/39494))

   * Compiling MySQL with `FALCON' support enabled with a compiler that
     does not support exceptions would fail to complete successfully.
     `configure' has been updated to switch off `FALCON' support if the
     specified compiler does not support exceptions.  (Bug#39419
     (http://bugs.mysql.com/39419))

   * Use of the `PACK_KEYS' or `MAX_ROWS' table option in *Note `ALTER
     TABLE': alter-table. should have triggered table reconstruction
     but did not.  (Bug#39372 (http://bugs.mysql.com/39372))

   * The server returned a column type of *Note `VARBINARY':
     binary-varbinary. rather than *Note `DATE': datetime. as the
     result from the `COALESCE()', `IFNULL()', `IF()', `GREATEST()', or
     `LEAST()' functions or `CASE' expression if the result was
     obtained using `filesort' in an anonymous temporary table during
     the query execution.  (Bug#39283 (http://bugs.mysql.com/39283))

   * Starting MySQL with `FALCON' support when MySQL has not been
     compiled with a compiler supporting exceptions would lead to
     strange errors and results. MySQL will now fail to initialize if
     you have compiled without exceptions enabled with the following
     message:

          081116 12:21:12 [ERROR] Falcon must be compiled with C++ exceptions enabled to work. Please adjust your compile flags.
          [Falcon] Error: Falcon exiting process

     (Bug#39260 (http://bugs.mysql.com/39260))

   * A server built using yaSSL for SSL support would crash if
     configured to use an RSA key and a client sent a cipher list
     containing a non-RSA key as acceptable.  (Bug#39178
     (http://bugs.mysql.com/39178))

   * When built with Valgrind, the server failed to access tables
     created with the `DATA DIRECTORY' or `INDEX DIRECTORY' table
     option.  (Bug#39102 (http://bugs.mysql.com/39102))

   * With binary logging enabled *Note `CREATE VIEW': create-view. was
     subject to possible buffer overwrite and a server crash.
     (Bug#39040 (http://bugs.mysql.com/39040))

   * The fast mutex implementation was subject to excessive lock
     contention.  (Bug#38941 (http://bugs.mysql.com/38941))

   * Use of `InnoDB' monitoring (*Note `SHOW ENGINE INNODB STATUS':
     show-engine. or one of the `InnoDB' Monitor tables) could cause a
     server crash due to invalid access to a shared variable in a
     concurrent environment.  (Bug#38883 (http://bugs.mysql.com/38883))

   * Column names constructed due to wild-card expansion done inside a
     stored procedure could point to freed memory if the expansion was
     performed after the first call to the stored procedure.
     (Bug#38823 (http://bugs.mysql.com/38823))

   * If delayed insert failed to upgrade the lock, it did not free the
     temporary memory storage used to keep newly constructed *Note
     `BLOB': blob. values in memory, resulting in a memory leak.
     (Bug#38693 (http://bugs.mysql.com/38693))

   * The server unnecessarily acquired a query cache mutex even with
     the query cache disabled, resulting in a small performance
     decrement.  (Bug#38551 (http://bugs.mysql.com/38551))

   * On Windows, a five-second delay occurred at shutdown of
     applications that used the embedded server.  (Bug#38522
     (http://bugs.mysql.com/38522))

   * On Solaris, a scheduling policy applied to the main server process
     could be unintentionally overwritten in client-servicing threads.
     (Bug#38477 (http://bugs.mysql.com/38477))

   * *Note `BACKUP DATABASE': backup-database. failed to use the native
     driver for a `Falcon' table if the table was partitioned.
     (Bug#38426 (http://bugs.mysql.com/38426))

   * On Windows, the embedded server would crash in *Note
     `mysql_library_init()': mysql-library-init. if the language file
     was missing.  (Bug#38293 (http://bugs.mysql.com/38293))

   * The Event Scheduler no longer logs `started in thread' or
     `executed' successfully messages to the error log.  (Bug#38066
     (http://bugs.mysql.com/38066))

   * Setting the `debug' system variable and executing a *Note
     `SELECT': select.  statement resulted in a Valgrind warning.
     (Bug#38023 (http://bugs.mysql.com/38023))

   * An incorrectly checked `XOR' subquery optimization resulted in an
     assertion failure.  (Bug#37899 (http://bugs.mysql.com/37899))

   * A *Note `SELECT': select. with a `NULL NOT IN' condition
     containing a complex subquery from the same table as in the outer
     select caused an assertion failure.  (Bug#37894
     (http://bugs.mysql.com/37894))

   * Use of an uninitialized constant in *Note `EXPLAIN': explain.
     evaluation caused an assertion failure.  (Bug#37870
     (http://bugs.mysql.com/37870))

   * The server did not shut down upon receipt of a `SIGINT' signal
     unless it was run within a debugger.  (Bug#37869
     (http://bugs.mysql.com/37869))

   * A query that could use one index to produce the desired ordering
     and another index for range access with index condition pushdown
     could cause a server crash.  (Bug#37851
     (http://bugs.mysql.com/37851))

   * Renaming an `ARCHIVE' table to the same name with different
     lettercase and then selecting from it could cause a server crash.
     (Bug#37719 (http://bugs.mysql.com/37719))

   * For queries executed with the batched-key access method, an
     incorrect value of an internal parameter caused a server crash if
     `join_buffer_size' was less then 256.  (Bug#37690
     (http://bugs.mysql.com/37690))

   * Compiling MySQL with `FALCON' support enabled on Solaris 9 using
     the Sun Studio compiler would fail with error:

          "Interlock.h", line 149: Error: #error cas not defined. We need>= Solaris 10.

     (Bug#37622 (http://bugs.mysql.com/37622))

   * `TIMEDIFF()' was erroneously treated as always returning a
     positive result. Also, `CAST()' of *Note `TIME': time. values to
     *Note `DECIMAL': numeric-types. dropped the sign of negative
     values.  (Bug#37553 (http://bugs.mysql.com/37553)) See also
     Bug#42525 (http://bugs.mysql.com/42525).

   * *Note `mysqlcheck': mysqlcheck. used *Note `SHOW FULL TABLES':
     show-tables. to get the list of tables in a database. For some
     problems, such as an empty `.frm' file for a table, this would
     fail and *Note `mysqlcheck': mysqlcheck.  then would neglect to
     check other tables in the database.  (Bug#37527
     (http://bugs.mysql.com/37527))

   * Updating a view with a subquery in the `CHECK' option could cause
     an assertion failure.  (Bug#37460 (http://bugs.mysql.com/37460))

   * Statements that displayed the value of system variables (for
     example, *Note `SHOW VARIABLES': show-variables.) expect variable
     values to be encoded in `character_set_system'. However, variables
     set from the command line such as `basedir' or `datadir' were
     encoded using `character_set_filesystem' and not converted
     correctly.  (Bug#37339 (http://bugs.mysql.com/37339))

   * On a 32-bit server built without big tables support, the offset
     argument in a `LIMIT' clause might be truncated due to a 64-bit to
     32-bit cast.  (Bug#37075 (http://bugs.mysql.com/37075))

   * Specifying a database name twice to *Note `BACKUP DATABASE':
     backup-database. caused a server crash. Now *Note `BACKUP
     DATABASE': backup-database. ignores duplicate names.  (Bug#36933
     (http://bugs.mysql.com/36933))

   * If a non-directory file `f' without an extension was created in
     the data directory, the server would allow clients to execute a
     `USE f' statement even though `f' could not be a database. The
     server now verifies that that the named database corresponds to a
     directory.  (Bug#36897 (http://bugs.mysql.com/36897))

   * The `FALCON' storage would silently recreate missing tablespace
     files if they did not exist. Errors are now written to the MySQL
     error log when the `FALCON' system tablespace files are found to
     be missing. Warnings are produce in the log file when attempting
     to access data tablespace files that do not exist.  (Bug#36804
     (http://bugs.mysql.com/36804))

   * Use of `CONVERT()' with `GROUP BY' to convert numeric values to
     *Note `CHAR': char. could return truncated results.  (Bug#36772
     (http://bugs.mysql.com/36772))

   * The *Note `mysql': mysql. client, when built with Visual Studio
     2005, did not display Japanese characters.  (Bug#36279
     (http://bugs.mysql.com/36279))

   * Setting the `slave_compressed_protocol' system variable to
     `DEFAULT' failed in the embedded server.  (Bug#35999
     (http://bugs.mysql.com/35999))

   * Processing for `NULL'-complemented rows in the result sets of
     queries with nested outer joins could be incorrect.  (Bug#35835
     (http://bugs.mysql.com/35835))

   * The columns that store character set and collation names in
     several `INFORMATION_SCHEMA' tables were lengthened because they
     were not long enough to store some possible values: *Note
     `SCHEMATA': schemata-table, *Note `TABLES': tables-table, *Note
     `COLUMNS': columns-table, *Note `CHARACTER_SETS':
     character-sets-table, *Note `COLLATIONS': collations-table, and
     *Note `COLLATION_CHARACTER_SET_APPLICABILITY':
     collation-character-set-applicability-table.  (Bug#35789
     (http://bugs.mysql.com/35789))

   * Queries executed using the batched-key access method could cause
     an assertion fail when key expressions for a `ref' access depended
     on columns not only from the previous join table.  (Bug#35685
     (http://bugs.mysql.com/35685))

   * Selecting from an `INFORMATION_SCHEMA' table into an incorrectly
     defined `MERGE' table caused an assertion failure.  (Bug#35068
     (http://bugs.mysql.com/35068))

   * *Note `perror': perror. on Windows did not know about Win32 system
     error codes.  (Bug#34825 (http://bugs.mysql.com/34825))

   * `EXPLAIN EXTENDED' evaluation of aggregate functions that required
     a temporary table caused a server crash.  (Bug#34773
     (http://bugs.mysql.com/34773))

   * *Note `BACKUP DATABASE': backup-database. produced an incorrect
     error message when the backup image file name contained a
     non-existent directory.  (Bug#34754 (http://bugs.mysql.com/34754))

   * *Note `SHOW GLOBAL STATUS': show-status. shows values that
     aggregate the session status values for all threads. This did not
     work correctly for the embedded server.  (Bug#34517
     (http://bugs.mysql.com/34517))

   * There were spurious warnings about `"Truncated incorrect DOUBLE
     value"' in queries with `MATCH ...  AGAINST' and `>' or `<' with a
     constant (which was reported as an incorrect `DOUBLE' value) in the
     `WHERE' condition.  (Bug#34374 (http://bugs.mysql.com/34374))

   * *Note `mysqldumpslow': mysqldumpslow. did not aggregate times.
     (Bug#34129 (http://bugs.mysql.com/34129))

   * *Note `mysql_config': mysql-config. did not output `-ldl' (or
     equivalent) when needed for `--libmysqld-libs', so its output
     could be insufficient to build applications that use the embedded
     server.  (Bug#34025 (http://bugs.mysql.com/34025))

   * For a stored procedure containing a `SELECT * ... RIGHT JOIN'
     query, execution failed for the second call.  (Bug#33811
     (http://bugs.mysql.com/33811))

   * The CSV storage engine had been modified to require columns to be
     explicitly specified as `NOT NULL' in `CREATE TABLE' statements.

     However, adding columns via the `ALTER TABLE' command allowed
     nullable columns to be added to an existing CSV table.  (Bug#33696
     (http://bugs.mysql.com/33696))

   * The `ROUTINES.DATA_TYPE',
     `REFERENTIAL_CONSTRAINTS.SPECIFIC_SCHEMA',
     `REFERENTIAL_CONSTRAINTS.SPECIFIC_NAME',
     `REFERENTIAL_CONSTRAINTS.PARAMETER_NAME',
     `REFERENTIAL_CONSTRAINTS.DATA_TYPE' columns were declared longer
     than the maximum allowed identifier length.  (Bug#33649
     (http://bugs.mysql.com/33649))

   * If a `TEMPORARY' table existed with the same name as a regular
     table, *Note `BACKUP DATABASE': backup-database. saved the
     temporary table, causing a subsequent *Note `RESTORE': restore. to
     fail.  (Bug#33574 (http://bugs.mysql.com/33574))

   * Previously, use of index hints with views (which do not have
     indexes) produced the error `ERROR 1221 (HY000): Incorrect usage
     of USE/IGNORE INDEX and VIEW'. Now this produces `ERROR 1176
     (HY000): Key '...' doesn't exist in table '...'', the same error
     as for base tables without an appropriate index.  (Bug#33461
     (http://bugs.mysql.com/33461))

   * Execution of a prepared statement that referred to a system
     variable caused a server crash.  (Bug#32124
     (http://bugs.mysql.com/32124))

   * Some division operations produced a result with incorrect
     precision.  (Bug#31616 (http://bugs.mysql.com/31616))

   * Server variables could not be set to their current values on Linux
     platforms. (These fixes are in addition to those made in MySQL
     6.0.5; additional fixes were made in MySQL 6.0.10.)  (Bug#31177
     (http://bugs.mysql.com/31177)) See also Bug#6958
     (http://bugs.mysql.com/6958).

   * For Solaris package installation using `pkgadd', the postinstall
     script failed, causing the system tables in the `mysql' database
     not to be created.  (Bug#31164 (http://bugs.mysql.com/31164))

   * For installation on Solaris using `pkgadd' packages, the *Note
     `mysql_install_db': mysql-install-db. script was generated in the
     `scripts' directory, but the temporary files used during the
     process were left there and not deleted.  (Bug#31052
     (http://bugs.mysql.com/31052))

   * Searching for text values on a column using a character set that
     provides multi-weight characters and sequences on an `INNODB' or
     `FALCON' table with an index would fail to find the expanded value.
     (Bug#29246 (http://bugs.mysql.com/29246))

   * Some *Note `SHOW': show. statements and retrievals from the
     `INFORMATION_SCHEMA' *Note `TRIGGERS': triggers-table. and *Note
     `EVENTS': events-table. tables used a temporary table and
     incremented the `Created_tmp_disk_tables' status variable, due to
     the way that `TEXT' columns are handled. The `TRIGGERS.SQL_MODE',
     `TRIGGERS.DEFINER', and `EVENTS.SQL_MODE' columns now are *Note
     `VARCHAR': char. to avoid this problem.  (Bug#29153
     (http://bugs.mysql.com/29153))

   * XA transaction rollbacks could result in corrupted transaction
     states and a server crash.  (Bug#28323
     (http://bugs.mysql.com/28323))

   * There were cases where string-to-number conversions would produce
     warnings for *Note `CHAR': char. values but not for *Note
     `VARCHAR': char. values.  (Bug#28299 (http://bugs.mysql.com/28299))

   * For several read only system variables that were viewable with
     *Note `SHOW VARIABLES': show-variables, attempting to view them
     with `SELECT @@VAR_NAME' or set their values with `SET' resulted
     in an `unknown system variable' error. Now they can be viewed with
     `SELECT @@VAR_NAME' and attempting to set their values results in
     a message indicating that they are read only.  (Bug#28234
     (http://bugs.mysql.com/28234))

   * *Note `ALTER TABLE': alter-table. for an *Note `ENUM': enum.
     column could change column values.  (Bug#23113
     (http://bugs.mysql.com/23113))

   * Setting the session value of the `max_allowed_packet' or
     `net_buffer_length' system variable was allowed but had no effect.
     The session value of these variables is now read only.  (Bug#22891
     (http://bugs.mysql.com/22891))

   * A race condition between the *Note `mysqld.exe': mysqld.  server
     and the Windows service manager could lead to inability to stop
     the server from the service manager.  (Bug#20430
     (http://bugs.mysql.com/20430))


File: manual.info,  Node: news-6-0-8,  Next: news-6-0-7,  Prev: news-6-0-9,  Up: news-6-0-x

C.1.4 Changes in MySQL 6.0.8 (03 November 2008)
-----------------------------------------------

Functionality added or changed:

   * *Incompatible Change*: The tables for MySQL Backup logging have
     been renamed, and the logging capabilities now are more flexible,
     similar to the capabilities provided for the general query log and
     slow query log.

        * The names of the MySQL Backup log tables in the `mysql'
          database have been changed from `online_backup' and
          `online_backup_progress' to `backup_history' and
          `backup_progress'.

        * Logging now can be enabled or disabled, it is possible to log
          to tables or to files, and the names of the log files can be
          changed. For details, see *Note
          backup-database-restore-log-control::.

        * A new statement, *Note `FLUSH BACKUP LOGS': flush, closes and
          reopens the backup log files. A new option for *Note
          `mysql_refresh()': mysql-refresh, `REFRESH_BACKUP_LOG',
          performs the same operation.

   * *Important Change*: The `--skip-thread-priority' option is now
     deprecated in MySQL 5.1 and is removed in MySQL 6.0 such that the
     server won't change the thread priorities by default. Giving
     threads different priorities might yield marginal improvements in
     some platforms (where it actually works), but it might instead
     cause significant degradation depending on the thread count and
     number of processors. Meddling with the thread priorities is a not
     a safe bet as it is very dependent on the behavior of the CPU
     scheduler and system where MySQL is being run.  (Bug#35164
     (http://bugs.mysql.com/35164), Bug#37536
     (http://bugs.mysql.com/37536))

   * *Important Change*: The `--log' option now is deprecated and will
     be removed (along with the `log' system variable) in the future.
     Instead, use the `--general_log' option to enable the general
     query log and the `--general_log_file=FILE_NAME' option to set the
     general query log file name. The values of these options are
     available in the `general_log' and `general_log_file' system
     variables, which can be changed at runtime.

     Similar changes were made for the `--log-slow-queries' option and
     `log_slow_queries' system variable. You should use the
     `--slow_query_log' and `--slow_query_log_file=FILE_NAME' options
     instead (and the `slow_query_log' and `slow_query_log_file' system
     variables).

   * The `BUILD/compile-solaris-*' scripts now compile MySQL with the
     `mtmalloc' library rather than `malloc'.  (Bug#38727
     (http://bugs.mysql.com/38727))

   * Binary distributions for Solaris, Linux, and Mac OS X now are
     built with support for the `pool-of-threads' value of
     `thread_handling'.  (Bug#38636 (http://bugs.mysql.com/38636))

   * *Note `BACKUP DATABASE': backup-database. now performs an implicit
     commit, like *Note `RESTORE': restore.  (Bug#38261
     (http://bugs.mysql.com/38261))

   * The deprecated `--default-table-type' server option has been
     removed.  (Bug#34818 (http://bugs.mysql.com/34818))

   * On WIndows, use of POSIX I/O interfaces in `mysys' was replaced
     with Win32 API calls (`CreateFile()', `WriteFile()', and so forth)
     and the default maximum number of open files has been increased to
     16384. The maximum can be increased further by using the
     `--open-files-limit=N' option at server startup.  (Bug#24509
     (http://bugs.mysql.com/24509))

   * Previously, prepared *Note `CALL': call.  statements could be used
     via the C API only for stored procedures that produce at most one
     result set, and applications could not use placeholders for `OUT'
     or `INOUT' parameters. For prepared *Note `CALL': call. statements
     used via *Note `PREPARE': prepare. and *Note `EXECUTE': execute,
     placeholders could not be used for `OUT' or `INOUT' parameters.

     For the C API, prepared *Note `CALL': call.  support now is
     expanded in the following ways:

        * A stored procedure can produce any number of result sets.
          The number of columns and the data types of the columns need
          not be the same for all result sets.

        * The final values of `OUT' and `INOUT' parameters are
          available to the calling application after the procedure
          returns. These parameters are returned as an extra single-row
          result set following any result sets produced by the
          procedure itself.  The row contains the values of the `OUT'
          and `INOUT' parameters in the order in which they are
          declared in the procedure parameter list.

        * A new C API function, *Note `mysql_stmt_next_result()':
          mysql-stmt-next-result, is available for processing stored
          procedure results. See *Note c-api-prepared-call-statements::.

        * The `CLIENT_MULTI_RESULTS' flag now is enabled by default. It
          no longer needs to be enabled when you call *Note
          `mysql_real_connect()': mysql-real-connect. (This flag is
          necessary for executing stored procedures because they can
          produce multiple result sets.)

     For *Note `PREPARE': prepare. and *Note `EXECUTE': execute,
     placeholder support for `OUT' and `INOUT' parameters is now
     available. See *Note call::.  (Bug#11638
     (http://bugs.mysql.com/11638), Bug#17898
     (http://bugs.mysql.com/17898))

   * MySQL now supports an interface for semisynchronous replication: A
     commit performed on the master side blocks before returning to the
     session that performed the transaction until at least one slave
     acknowleges that it has received and logged the events for the
     transaction. Semisynchronous replication is implemented through an
     optional plugin component. See *Note replication-semisync::

   * Most statements that previously caused an implicit commit before
     executing now also cause an implicit commit after executing.
     Also, the *Note `FLUSH': flush. statement and *Note
     `mysql_refresh()': mysql-refresh. C API function now cause an
     implicit commit. See *Note implicit-commit::.

   * The `FILES' and `TABLESPACES' tables have been added to
     `INFORMATION_SCHEMA' for tracking the individual files and
     tablespace details for `Falcon'. In addition, the `TABLES' table
     has been extended to incorporate the `TABLESPACE_NAME' field to
     specify the tablespace name that a specific table belongs to.

Bugs fixed:

   * *Incompatible Change*: *Note `CHECK TABLE ... FOR UPGRADE':
     check-table. did not check for incompatible collation changes made
     in MySQL 5.1.21 (Bug#29499 (http://bugs.mysql.com/29499)) and
     5.1.23 (Bug#27562 (http://bugs.mysql.com/27562), Bug#29461
     (http://bugs.mysql.com/29461)). This also affects *Note
     `mysqlcheck': mysqlcheck. and *Note `mysql_upgrade':
     mysql-upgrade, which cause that statement to be executed. See
     *Note checking-index-changes::.  (Bug#39585
     (http://bugs.mysql.com/39585)) See also Bug#40984
     (http://bugs.mysql.com/40984).

   * *Incompatible Change*: In connection with view creation, the
     server created `arc' directories inside database directories and
     maintained useless copies of `.frm' files there. Creation and
     renaming procedures of those copies as well as creation of `arc'
     directories has been discontinued.

     This change does cause a problem when downgrading to older server
     versions which manifests itself under these circumstances:

       1. Create a view `v_orig' in MySQL 6.0.8 or higher.

       2. Rename the view to `v_new' and then back to `v_orig'.

       3. Downgrade to an older 6.0.x server and run *Note
          `mysql_upgrade': mysql-upgrade.

       4. Try to rename `v_orig' to `v_new' again. This operation fails.

     As a workaround to avoid this problem, use either of these
     approaches:

        * Dump your data using *Note `mysqldump': mysqldump. before
          downgrading and reload the dump file after downgrading.

        * Instead of renaming a view after the downgrade, drop it and
          recreate it.

     The downgrade problem introduced by the fix for this bug has been
     addressed as Bug#40021 (http://bugs.mysql.com/40021).  (Bug#17823
     (http://bugs.mysql.com/17823))

   * *Important Change*: *Replication*: The `SUPER' privilege is now
     required to change the session value of `binlog_format' as well as
     its global value. For more information about `binlog_format', see
     *Note replication-formats::.  (Bug#39106
     (http://bugs.mysql.com/39106))

   * *Partitioning*: *Replication*: Replication to partitioned `MyISAM'
     tables could be slow with row-based binary logging.  (Bug#35843
     (http://bugs.mysql.com/35843))

   * *Partitioning*: A duplicate key error raised when inserting into a
     partitioned table used a different error code from that returned
     by such an error raised when inserting into a table that was not
     partitioned.  (Bug#38719 (http://bugs.mysql.com/38719)) See also
     Bug#28842 (http://bugs.mysql.com/28842).

   * *Partitioning*: If an error occurred when evaluating a column of a
     partitioned table for the partitioning function, the row could be
     inserted anyway.  (Bug#38083 (http://bugs.mysql.com/38083))

   * *Partitioning*: Using *Note `INSERT ... SELECT': insert-select. to
     insert records into a partitioned `MyISAM' table could fail if
     some partitions were empty and others are not.  (Bug#38005
     (http://bugs.mysql.com/38005))

   * *Replication*: Issuing the statement `CHANGE MASTER TO ...
     MASTER_HEARTBEAT_PERIOD = PERIOD' using a value for PERIOD outside
     the permitted range caused the slave to crash.  (Bug#39077
     (http://bugs.mysql.com/39077))

   * *Replication*: Replication of `BLACKHOLE' tables did not work with
     row-based binary logging.  (Bug#38360
     (http://bugs.mysql.com/38360))

   * *Replication*: In some cases, a replication master sent a special
     event to a reconnecting slave to keep the slave's temporary
     tables, but they still had references to the `old' slave SQL
     thread and used them to access that thread's data.  (Bug#38269
     (http://bugs.mysql.com/38269))

   * *Replication*: Replication filtering rules were inappropiately
     applied when executing *Note `BINLOG': binlog. pseudo-queries.
     One way in which this problem showed itself was that, when
     replaying a binary log with *Note `mysqlbinlog': mysqlbinlog, RBR
     events were sometimes not executed if the `--replicate-do-db'
     option was specified. Now replication rules are applied only to
     those events executed by the slave SQL thread.  (Bug#36099
     (http://bugs.mysql.com/36099))

   * *Replication*: For a `CREATE TABLE ... SELECT' statement that
     creates a table in a database other than the current one, the
     table could be created in the wrong database on replication slaves
     if row-based binary logging is used.  (Bug#34707
     (http://bugs.mysql.com/34707))

   * *Replication*: A statement did not always commit or roll back
     correctly when the server was shut down; the error could be
     triggered by having a failing *Note `UPDATE': update. or *Note
     `INSERT': insert. statement on a transactional table, causing an
     implicit rollback.  (Bug#32709 (http://bugs.mysql.com/32709)) See
     also Bug#38262 (http://bugs.mysql.com/38262).

   * Compiling using `--with-falcon' on Mac OS X fails if you use
     `CXX=gcc'. You must specify that the `g++' compiler should be used
     for C++ using `CXX=g++'.  (Bug#41270 (http://bugs.mysql.com/41270))

   * When building `Falcon' support on Solaris 10 on the SPARC
     platform, falcon would not be compiled even when explicitly
     enabled.  (Bug#40390 (http://bugs.mysql.com/40390))

   * Running an online `DROP INDEX' operation on an index using the
     same key on a `Falcon' table would fail with an assertion.
     (Bug#40265 (http://bugs.mysql.com/40265))

   * With `innodb_autoinc_lock_mode' set to 0 (`traditional' locking),
     deadlock and lock-wait timeout errors encountered while reading
     `AUTO_INCREMENT' values were being reported as a generic
     `AUTO_INCREMENT' value allocation failure. (The actual error
     encountered was printed in the error log.) The transaction was
     being rolled back but all the user saw was an `AUTO_INCREMENT'
     failure code. Now the actual locking error code is returned to the
     user.  (Bug#40224 (http://bugs.mysql.com/40224))

   * Optimized builds of *Note `mysqld': mysqld. crashed when built
     with Sun Studio on SPARC platforms.  (Bug#40224
     (http://bugs.mysql.com/40224))

   * Creating a table, or selecting from a table using the `FALCON'
     storage engine and with a double quote in the name would cause an
     assertion failure.  (Bug#40158 (http://bugs.mysql.com/40158),
     Bug#39388 (http://bugs.mysql.com/39388))

   * Windows builds were missing the MySQL Backup log tables.
     (Bug#40126 (http://bugs.mysql.com/40126))

   * The maximum value for `falcon-serial-log-buffer' has been reduced
     to 1000.  (Bug#40123 (http://bugs.mysql.com/40123))

   * The indexes and record contents of a `FALCON' table could get out
     of synchronization during a lrge number of updates. Because
     `FALCON' returns data only if it matches both the index and record
     data the result sets returned could be invalid when comparing the
     results of an index and non-index based `SELECT'.  (Bug#40112
     (http://bugs.mysql.com/40112), Bug#40130
     (http://bugs.mysql.com/40130))

   * The *Note `CHECK TABLE ... FOR UPGRADE': check-table. statement
     did not check for incompatible collation changes made in MySQL
     5.1.24 (Bug#27877 (http://bugs.mysql.com/27877)). This also
     affects *Note `mysqlcheck': mysqlcheck. and *Note `mysql_upgrade':
     mysql-upgrade, which cause that statement to be executed. See
     *Note checking-index-changes::.

     Prior to this fix, a binary upgrade (performed without dumping
     tables with *Note `mysqldump': mysqldump. before the upgrade and
     reloading the dump file after the upgrade) would corrupt tables
     that have indexes that use the `utf8_general_ci' or
     `ucs2_general_ci' collation for columns that contain `'ss'' LATIN
     SMALL LETTER SHARP S (German). After the fix, *Note `CHECK TABLE
     ... FOR UPGRADE': check-table. properly detects the problem and
     warns about tables that need repair.

     However, the fix is not backward compatible and can result in a
     downgrading problem under these circumstances:

       1. Perform a binary upgrade to a version of MySQL that includes
          the fix.

       2. Run *Note `CHECK TABLE ... FOR UPGRADE': check-table. (or
          *Note `mysqlcheck': mysqlcheck.  or *Note `mysql_upgrade':
          mysql-upgrade.) to upgrade tables.

       3. Perform a binary downgrade to a version of MySQL that does
          not include the fix.

     The solution is to dump tables with *Note `mysqldump': mysqldump.
     before the downgrade and reload the dump file after the downgrade.
     Alternatively, drop and recreate affected indexes.  (Bug#40053
     (http://bugs.mysql.com/40053))

   * MySQL may crash during the recover of `Falcon' tables if the
     server was shutdown after a large data load.  (Bug#39951
     (http://bugs.mysql.com/39951))

   * Non-ASCII error messages were corrupted.  (Bug#39949
     (http://bugs.mysql.com/39949))

   * The `Threads_created' status variable was not correctly
     incremented when the server was started with the
     `--thread-handling=pool-of-threads' option.  (Bug#39916
     (http://bugs.mysql.com/39916))

   * When the `Falcon' serial log reaches a state where the serial log
     can no longer be written to, for example when the disk is full, or
     when permissions have been changed on an open log, then MySQL
     could crash.  (Bug#39912 (http://bugs.mysql.com/39912))

   * On Windows Vista, *Note `RESTORE': restore. did not correctly
     calculate the validity point from the backup stream.  (Bug#39825
     (http://bugs.mysql.com/39825))

   * `Falcon' did not support online add/drop index creation on tables
     using a `NOT NULL' column.  (Bug#39795
     (http://bugs.mysql.com/39795))

   * When creating a table with the `FALCON' engine where the size of
     the key in the index was larger than supported (the error message
     did not signify the severity of the problem.  The message and
     error has been updated.  (Bug#39708 (http://bugs.mysql.com/39708))

   * Recovery of `Falcon' tables could crash because of an invalid or
     unrecognised tablespace ID.  (Bug#39706
     (http://bugs.mysql.com/39706))

   * Performing an `INSERT' on `Maria' table with a `UNIQUE' column,
     MySQL could deadlock.  (Bug#39697 (http://bugs.mysql.com/39697))

   * Memory would be allocated for the `Falcon' sector cache even if
     the cache had been disabled (`falcon_use_sectorcache').
     (Bug#39692 (http://bugs.mysql.com/39692))

   * The MySQL Backup `backup_history' log now contains a
     `backup_file_path' column.  `backup_file' contains the basename and
     `backup_file_path' contains the directory of the image file path
     name.  (Bug#39690 (http://bugs.mysql.com/39690))

   * Some MySQL Backup-related memory-use warnings detected by Valgrind
     were corrected.  (Bug#39598 (http://bugs.mysql.com/39598))

   * Creating a table with a comment of 62 characters or longer caused
     a server crash.  (Bug#39591 (http://bugs.mysql.com/39591))

   * When loading very large datasets into a `Falcon' table, MySQL may
     crash because the size of the Falcon serial log exceeds 4GB. The
     maximum supported size of the serial log file has been increased
     from a 32-bit to a 64-bit integer to handle larger log file sizes.
     (Bug#39575 (http://bugs.mysql.com/39575))

   * When recovering a crashed `Falcon' table when the page size had
     been set to 32K, MySQL could crash with an assertion.  (Bug#39574
     (http://bugs.mysql.com/39574))

   * The Sun Studio compiler failed to build debug versions of the
     server due to use of features specific to `gcc'.  (Bug#39451
     (http://bugs.mysql.com/39451))

   * When performing a recovery of a crashed `Falcon' table on Windows,
     MySQL would report an exception when then recovery process
     completed, even though the recovery may have completed
     successfully.  (Bug#39421 (http://bugs.mysql.com/39421))

   * Performing an `ALTER TABLE' on a `Maria' table where you are
     changing the column name but not the type, a full table rebuild
     may be triggered, instead of just a simple rename.  (Bug#39399
     (http://bugs.mysql.com/39399))

   * Dropping a locked `Maria' table leads to an assertion failure.
     (Bug#39395 (http://bugs.mysql.com/39395))

   * For a *Note `TIMESTAMP': datetime. column in an `InnoDB' table,
     testing the column with multiple conditions in the `WHERE' clause
     caused a server crash.  (Bug#39353 (http://bugs.mysql.com/39353))

   * When using a `Falcon' table, equals (=) comparison of values of
     columns of type `YEAR' does not work when an index is present on
     the `YEAR' column(s).  (Bug#39342 (http://bugs.mysql.com/39342))

   * When running `TRUNCATE' on a table where other threads are also
     trying to access the same `Falcon' table, a deadlock could occur
     between the two executing threads.  (Bug#39321
     (http://bugs.mysql.com/39321))

   * Performing a `INSERT INTO ... ON DUPLICATE KEY UPDATE' statement
     on a `Maria' table would fail with the error `1178: The storage
     engine for the table doesn't support UPDATE in WRITE CONCURRENT'.
     (Bug#39248 (http://bugs.mysql.com/39248))

   * `Maria' could fail to find data in a table with an index on a
     `char' column.  (Bug#39243 (http://bugs.mysql.com/39243))

   * Running `ALTER TABLE PARTITION' on a `Maria' table would lead to a
     crash.  (Bug#39227 (http://bugs.mysql.com/39227))

   * Using `Maria', executing `FLUSH TABLES WITH READ LOCK' after a
     `LOCK TABLES' statement would lead to a crash.  (Bug#39226
     (http://bugs.mysql.com/39226))

   * When using `Falcon' on ReiserFS file systems, the initial size of
     the serial log could cause problems during recovery if the size of
     the log file was less than 4KB. The minimum size of the serial log
     file has now been increased to 8KB to address the problem.
     (Bug#39212 (http://bugs.mysql.com/39212))

   * Running multiple `SELECT', `INSERT', `UPDATE' and `DELETE' queries
     on the `Maria' table could lead to a deadlock.  (Bug#39210
     (http://bugs.mysql.com/39210))

   * For *Note `BACKUP DATABASE': backup-database, the server could add
     a `/' character to the end of the backup path, even when the path
     ended with a file name rather than a directory name.  (Bug#39189
     (http://bugs.mysql.com/39189))

   * The server could crash when attempting to insert duplicate empty
     strings into a `utf8' `SET' column.  (Bug#39186
     (http://bugs.mysql.com/39186))

   * References to local variables in stored procedures are replaced
     with `NAME_CONST(NAME, VALUE)' when written to the binary log.
     However, an `illegal mix of collation' error might occur when
     executing the log contents if the value's collation differed from
     that of the variable. Now information about the variable collation
     is written as well.  (Bug#39182 (http://bugs.mysql.com/39182))

   * Building MySQL with `Falcon' support using Sun Studio 10 would
     fail due to GNU CC specific code within `MemoryManager.h'.
     (Bug#39181 (http://bugs.mysql.com/39181))

   * *Note `BACKUP DATABASE': backup-database. failed on PowerMac
     platforms due to type casting problems.  (Bug#39127
     (http://bugs.mysql.com/39127))

   * MySQL Backup was not handling several errors.  (Bug#39089
     (http://bugs.mysql.com/39089))

   * Some warnings were being reported as errors.  (Bug#39059
     (http://bugs.mysql.com/39059))

   * Queries of the form `SELECT ... REGEXP BINARY NULL' could lead to
     a hung or crashed server.  (Bug#39021
     (http://bugs.mysql.com/39021))

   * Statements of the form `INSERT ... SELECT .. ON DUPLICATE KEY
     UPDATE COL_NAME = DEFAULT' could result in a server crash.
     (Bug#39002 (http://bugs.mysql.com/39002))

   * Repeated `CREATE TABLE ... SELECT' statements, where the created
     table contained an `AUTO_INCREMENT' column, could lead to an
     assertion failure.  (Bug#38821 (http://bugs.mysql.com/38821))

   * *Note `RESTORE': restore. crashed if a trigger and an event had
     the same name.  (Bug#38810 (http://bugs.mysql.com/38810))

   * For deadlock between two transactions that required a timeout to
     resolve, all server tables became inaccessible for the duration of
     the deadlock.  (Bug#38804 (http://bugs.mysql.com/38804))

   * Running multiple `SELECT' operations on the same `Falcon' table
     could lead to an assertion within the `Transaction::initialize'.
     The same operation could also lead to a deadlock situation on the
     specified table.  (Bug#38739 (http://bugs.mysql.com/38739),
     Bug#38748 (http://bugs.mysql.com/38748))

   * When inserting a string into a duplicate-key error message, the
     server could improperly interpret the string, resulting in a crash.
     (Bug#38701 (http://bugs.mysql.com/38701))

   * A race condition between threads sometimes caused unallocated
     memory to be addressed.  (Bug#38692 (http://bugs.mysql.com/38692))

   * A server crash resulted from concurrent execution of a
     multiple-table *Note `UPDATE': update. that used a `NATURAL' or
     `USING' join together with *Note `FLUSH TABLES WITH READ LOCK':
     flush. or *Note `ALTER TABLE': alter-table. for the table being
     updated.  (Bug#38691 (http://bugs.mysql.com/38691))

   * On ActiveState Perl, `mysql-test-run.pl --start-and-exit' started
     but did not exit.  (Bug#38629 (http://bugs.mysql.com/38629))

   * Executing a light `INSERT' and `UPDATE' workload with
     `falcon_index_chill_threshold' set to 4K and
     `falcon_record_chill_threshold' set to to 4K, MySQL could crash.
     (Bug#38566 (http://bugs.mysql.com/38566))

   * A server crash resulted from execution of an *Note `UPDATE':
     update. that used a derived table together with *Note `FLUSH
     TABLES': flush.  (Bug#38499 (http://bugs.mysql.com/38499))

   * Stored procedures involving substrings could crash the server on
     certain platforms due to invalid memory reads.  (Bug#38469
     (http://bugs.mysql.com/38469))

   * The binary log file name stored in the `binlog_file' column of the
     `mysql.backup_history' MySQL Backup table now is the file basename
     (the final component). Previously, the full path name was stored,
     but this could be too long for the column width.  (Bug#38462
     (http://bugs.mysql.com/38462))

   * On Windows, starting the server with the `--external-locking=1'
     option caused *Note `BACKUP DATABASE': backup-database. to fail.
     (Bug#38342 (http://bugs.mysql.com/38342))

   * Inserting data into columns within a `Falcon' table that contains
     columns with names containing accented characters would cause the
     data to be null (empty).  (Bug#38304 (http://bugs.mysql.com/38304))

   * The `innodb_log_arch_dir'
     (http://dev.mysql.com/doc/refman/5.1/en/innodb-parameters.html#sysvar_innodb_log_arch_dir)
     system variable is no longer available but was present in some of
     the sample option files included with MySQL distributions (such as
     `my-huge.cnf'). The line was present as a comment but uncommenting
     it would cause server startup failure so the line has been removed.
     (Bug#38249 (http://bugs.mysql.com/38249))

   * Errors during server startup caused destruction of an
     uninitialized mutex and assertion failure.  (Bug#37961
     (http://bugs.mysql.com/37961))

   * The handlerton-to-plugin mapping implementation did not free
     handler plugin references when the plugin was uninstalled,
     resulting in a server crash after several install/uninstall
     cycles. Also, on Mac OS X, the server crashed when trying to
     access an `EXAMPLE' table after the `EXAMPLE' plugin was installed.
     (Bug#37958 (http://bugs.mysql.com/37958))

   * The server crashed if an argument to a stored procedure was a
     subquery that returned more than one row.  (Bug#37949
     (http://bugs.mysql.com/37949))

   * When analyzing the possible index use cases, the server was
     incorrectly reusing an internal structure, leading to a server
     crash.  (Bug#37943 (http://bugs.mysql.com/37943))

   * Access checks were skipped for *Note `SHOW PROCEDURE STATUS':
     show-procedure-status. and *Note `SHOW FUNCTION STATUS':
     show-function-status, which could lead to a server crash or
     insufficient access checks in subsequent statements.  (Bug#37908
     (http://bugs.mysql.com/37908))

   * Comparisons could hang for `SET' or *Note `ENUM': enum. columns
     that used `latin2_czech_cs' collation.  (Bug#37854
     (http://bugs.mysql.com/37854))

   * It was possible to create a tasblespace using the name of one of
     the `Falcon' system tablespaces, `FALCON_MASTER',
     `FALCON_TEMPORARY', or `FALCON_BACKLOG' without an error message
     being raised. A suitable error is now produced when an attempt is
     made to create a table with the same name as a `Falcon' system
     tablespace.  (Bug#37668 (http://bugs.mysql.com/37668))

   * *Note `SHOW PROCESSLIST': show-processlist. displayed `copy to tmp
     table' when no such copy was occurring.  (Bug#37550
     (http://bugs.mysql.com/37550))

   * The `<=>' operator could return incorrect results when comparing
     `NULL' to *Note `DATE': datetime, *Note `TIME': time, or *Note
     `DATETIME': datetime. values.  (Bug#37526
     (http://bugs.mysql.com/37526))

   * MySQL Backup was not consistently checking for `BSTREAM_ERROR'
     errors.  (Bug#37522 (http://bugs.mysql.com/37522))

   * The combination of a subquery with a `GROUP BY', an aggregate
     function calculated outside the subquery, and a `GROUP BY' on the
     outer *Note `SELECT': select. could cause the server to crash.
     (Bug#37348 (http://bugs.mysql.com/37348))

   * Incorrect *Note `BLOB': blob. handling by *Note `RESTORE':
     restore. could result in a server crash.  (Bug#37212
     (http://bugs.mysql.com/37212))

   * The `NO_BACKSLASH_ESCAPES' SQL mode was ignored for *Note `LOAD
     DATA INFILE': load-data. and `SELECT INTO ... OUTFILE'.  The
     setting is taken into account now.  (Bug#37114
     (http://bugs.mysql.com/37114))

   * If thread-pooling was used and a connection attempt was denied on
     the grounds of exceeding the user limits, the number of active
     connections for that user was erroneously decreased twice. The
     difference between the actual number connections and the internal
     count could then cause debug builds of the server to raise an
     assertion.  (Bug#36970 (http://bugs.mysql.com/36970))

   * Long error messages for *Note `RESTORE': restore.  could be
     truncated.  (Bug#36854 (http://bugs.mysql.com/36854))

   * Running in strict mode, with a `auto_increment_increment' and
     `auto_increment_offset' set to a value larger than supportedf by
     the specified auto increment column within a `Falcon' table, a
     crash would occur.  (Bug#36473 (http://bugs.mysql.com/36473))

   * In some cases, references to views were confused with references
     to anonymous tables and privilege checking was not performed.
     (Bug#36086 (http://bugs.mysql.com/36086))

   * For crash reports on Windows, symbol names in stack traces were
     not correctly resolved.  (Bug#35987 (http://bugs.mysql.com/35987))

   * *Note `ALTER EVENT': alter-event. changed the `PRESERVE' attribute
     of an event even when `PRESERVE' was not specified in the
     statement.  (Bug#35981 (http://bugs.mysql.com/35981))

   * Host name values in SQL statements were not being checked for
     `'@'', which is illegal according to RFC952.  (Bug#35924
     (http://bugs.mysql.com/35924))

   * *Note `mysql_install_db': mysql-install-db. failed on machines
     that had the host name set to `localhost'.  (Bug#35754
     (http://bugs.mysql.com/35754))

   * Dynamic plugins failed to load on i5/OS.  (Bug#35743
     (http://bugs.mysql.com/35743))

   * With the `PAD_CHAR_TO_FULL_LENGTH' SQL mode enabled, a `ucs2'
     *Note `CHAR': char. column returned additional garbage after
     trailing space characters.  (Bug#35720
     (http://bugs.mysql.com/35720))

   * *Note `RESTORE': restore. did not set the `validity_point_time',
     `binlog_pos', and `binlog_file' fields of the `backup_history' log
     table row.  (Bug#35240 (http://bugs.mysql.com/35240))

   * With binary logging enabled, `CREATE TABLE ...  SELECT' failed if
     the source table was a log table.  (Bug#34306
     (http://bugs.mysql.com/34306))

   * If *Note `BACKUP DATABASE': backup-database. and *Note `RESTORE':
     restore. were done in a session with autocommit disabled, a later
     *Note `DROP TABLE': drop-table. or *Note `RESTORE': restore. in the
     same session failed.  (Bug#34204 (http://bugs.mysql.com/34204))

   * The `secure_file_priv' system variable now applies to *Note
     `BACKUP DATABASE': backup-database. and *Note `RESTORE': restore.
     operations: If the value is nonempty, backup and restore
     operations can read and write files only in the given directory.
     (Bug#34171 (http://bugs.mysql.com/34171))

   * *Note `mysql_real_connect()': mysql-real-connect. did not check
     whether the `MYSQL' connection handler was already connected and
     connected again even if so. Now an `CR_ALREADY_CONNECTED' error
     occurs.  (Bug#33831 (http://bugs.mysql.com/33831))

   * Shutting down the MySQL Server immediately following the execution
     of a *Note `BACKUP DATABASE': backup-database.  statement caused
     the server to crash if the database to be backed up contained any
     `Falcon' tables.  (Bug#33575 (http://bugs.mysql.com/33575))

   * The server crashed for *Note `BACKUP DATABASE': backup-database.
     if the backup progress tables in the `mysql' database were missing
     or created incorrectly.  (Bug#33352 (http://bugs.mysql.com/33352))

   * *Note `CHECKSUM TABLE': checksum-table. was not killable with
     *Note `KILL QUERY': kill.  (Bug#33146
     (http://bugs.mysql.com/33146))

   * A trigger for an `InnoDB' table activating multiple times could
     lead to `AUTO_INCREMENT' gaps.  (Bug#31612
     (http://bugs.mysql.com/31612))

   * *Note `mysqldump': mysqldump. could fail to dump views containing
     a large number of columns.  (Bug#31434
     (http://bugs.mysql.com/31434))

   * The server could improperly type user-defined variables used in
     the select list of a query.  (Bug#26020
     (http://bugs.mysql.com/26020))

   * For access to the *Note `INFORMATION_SCHEMA.VIEWS': views-table.
     table, the server did not check the `SHOW VIEW' and *Note
     `SELECT': select.  privileges, leading to inconsistency between
     output from that table and the *Note `SHOW CREATE VIEW':
     show-create-view.  statement.  (Bug#22763
     (http://bugs.mysql.com/22763))

   * `mysqld_safe' would sometimes fail to remove the pid file for the
     old `mysql' process after a crash. As a result, the server would
     fail to start due to a false `A mysqld process already exists...'
     error.  (Bug#11122 (http://bugs.mysql.com/11122))


File: manual.info,  Node: news-6-0-7,  Next: news-6-0-6,  Prev: news-6-0-8,  Up: news-6-0-x

C.1.5 Changes in MySQL 6.0.7 (29 September 2008)
------------------------------------------------

Functionality added or changed:

   * *Important Change*: *Note `mysqlbinlog': mysqlbinlog. now supports
     `--verbose' and `--base64-output=DECODE-ROWS' options to display
     row events as commented SQL statements. (The default otherwise is
     to display row events encoded as base-64 strings using *Note
     `BINLOG': binlog. statements.)  See *Note mysqlbinlog-row-events::.
     (Bug#31455 (http://bugs.mysql.com/31455))

   * `Falcon' builds on AMD64 platforms now.  (Bug#38535
     (http://bugs.mysql.com/38535))

   * `mysqltest' now installs signal handlers and generates a stack
     trace if it crashes.  (Bug#37003 (http://bugs.mysql.com/37003))

   * A new system variable, `backupdir', enables the default directory
     to be specified for *Note `BACKUP DATABASE': backup-database. and
     *Note `RESTORE': restore.  operations when the image file path
     name is not a full path name. The default value for this variable
     is the data directory.  (Bug#35230 (http://bugs.mysql.com/35230))

   * The `mysql.online_backup' and `mysql.online_backup_progress'
     tables now have a default character set of `utf8' rather than
     `latin1'.  (Bug#33836 (http://bugs.mysql.com/33836))

   * `mysqltest' was changed to be more robust in the case of a race
     condition that can occur for rapid disconnect/connect sequences
     with the server. The account used by `mysqltest' could reach its
     allowed simultaneous-sessions user limit if the connect attempt
     occurred before the server had fully processed the preceding
     disconnect.  `mysqltest' now checks specificaly for a user-limits
     error when it connects; if that error occurs, it delays briefly
     before retrying.  (Bug#23921 (http://bugs.mysql.com/23921))

   * Previously, *Note `BACKUP DATABASE': backup-database. did not back
     up privileges and *Note `RESTORE': restore. did not restore them.
     Now privileges for backed-up databases are saved. This includes
     privileges at the database level and below (table, column,
     routine). Global privileges are not saved. For additional
     information about how privileges are backed up, see *Note
     backup-database-restore-quick-guide::.

   * A new session system variable, `backup_wait_timeout', controls the
     number of seconds a *Note `BACKUP DATABASE': backup-database. or
     *Note `RESTORE': restore.  operation waits for a blocked DDL
     statements before aborting with an error.

   * The `CREATE TABLESPACE' privilege has been introduced. This
     privilege exists at the global (superuser) level and enables you
     to create, alter, and drop tablespaces and logfile groups.

   * Improvements made to MySQL Backup (the *Note `BACKUP DATABASE':
     backup-database. and *Note `RESTORE': restore. statements):

        * A native driver for the `MyISAM' storage engine is included.
          This results in faster times for backup and restore
          operations, although the size of backup image files is larger.

Bugs fixed:

   * *Security Enhancement*: The server consumed excess memory while
     parsing statements with hundreds or thousands of nested boolean
     conditions (such as `OR (OR ... (OR ... ))'). This could lead to a
     server crash or incorrect statement execution, or cause other
     client statements to fail due to lack of memory. The latter result
     constitutes a denial of service.  (Bug#38296
     (http://bugs.mysql.com/38296))

   * *Incompatible Change*: There were some problems using `DllMain()'
     hook functions on Windows that automatically do global and
     per-thread initialization for `libmysqld.dll':

        * Per-thread initialization: MySQL internally counts the number
          of active threads, which causes a delay in `my_end()' if not
          all threads have exited. But there are threads that can be
          started either by Windows internally (often in TCP/IP
          scenarios) or by users.  Those threads do not necessarily use
          `libmysql.dll' functionality but still contribute to the
          open-thread count. (One symptom is a five-second delay in
          times for PHP scripts to finish.)

        * Process-initialization: *Note `my_init()': my-init. calls
          `WSAStartup' that itself loads DLLs and can lead to a
          deadlock in the Windows loader.

     To correct these problems, DLL initialization code now is not
     invoked from `libmysql.dll' by default.  (Bug#37226
     (http://bugs.mysql.com/37226), Bug#33031
     (http://bugs.mysql.com/33031))

   * *Incompatible Change*: Some performance problems of *Note `SHOW
     ENGINE INNODB STATUS': show-engine. were reduced by removing `used
     cells' and `Total number of lock structs in row lock hash table'
     from the output. Now these values are present only if the
     `UNIV_DEBUG' symbol is defined at MySQL build time.  (Bug#36941
     (http://bugs.mysql.com/36941), Bug#36942
     (http://bugs.mysql.com/36942))

   * *Important Change*: The `INFORMATION_SCHEMA.FALCON_TABLES' table
     has been removed.  (Bug#29211 (http://bugs.mysql.com/29211),
     Bug#34705 (http://bugs.mysql.com/34705), Bug#34706
     (http://bugs.mysql.com/34706))

   * *Partitioning*: When a partitioned table had a *Note `TIMESTAMP':
     datetime. column defined with `CURRENT_TIMESTAMP' as the default
     but with no `ON UPDATE' clause, the column's value was incorrectly
     set to `CURRENT_TIMESTAMP' when updating across partitions.
     (Bug#38272 (http://bugs.mysql.com/38272))

   * *Partitioning*: A `LIST' partitioned `MyISAM' table returned
     erroneous results when an index was present on a column in the
     `WHERE' clause and `NOT IN' was used on that column.

     Searches using the index were also much slower then if the index
     were not present.  (Bug#35931 (http://bugs.mysql.com/35931))

   * *Partitioning*: `SELECT COUNT(*)' was not correct for some
     partitioned tables using a storage engine that did not support
     `HA_STATS_RECORDS_IS_EXACT'. Tables using the `ARCHIVE' storage
     engine were known to be affected.

     This was because `ha_partition::records()' was not implemented,
     and so the default `handler::records()' was used in its place.
     However, this is not correct behavior if the storage engine does
     not support `HA_STATS_RECORDS_IS_EXACT'.

     The solution was to implement `ha_partition::records()' as a
     wrapper around the underlying partition records.

     As a result of this fix, the rows column in the output of `EXPLAIN
     PARTITIONS' now includes the total number of records in the
     partitioned table.  (Bug#35745 (http://bugs.mysql.com/35745))

   * *Replication*: Server code used in binary logging could in some
     cases be invoked even though binary logging was not actually
     enabled, leading to asserts and other server errors.  (Bug#38798
     (http://bugs.mysql.com/38798))

   * *Replication*: Row-based replication broke for `utf8' *Note
     `CHAR': char. columns longer than 85 characters.  (Bug#37426
     (http://bugs.mysql.com/37426))

   * *Replication*: When `autocommit' was set equal to `1' after
     starting a transaction, the binary log did not commit the
     outstanding transaction. The reason this happened was that the
     binary log commit function saw only the values of the new
     settings, and decided that there was nothing to commit.

     This issue was first observed when using the `Falcon' storage
     engine, but it is possible that it affected other storage engines
     as well.  (Bug#37221 (http://bugs.mysql.com/37221))

   * *Replication*: Some kinds of internal errors, such as `Out of
     memory' errors, could cause the server to crash when replicating
     statements with user variables.

     certain internal errors.  (Bug#37150 (http://bugs.mysql.com/37150))

   * *Replication*: Row-based replication did not correctly copy *Note
     `TIMESTAMP': datetime. values from a big-endian storage engine to
     a little-endian storage engine.  (Bug#37076
     (http://bugs.mysql.com/37076))

   * *Replication*: The `--replicate-*-table' options were not
     evaluated correctly when replicating multi-table updates.

     As a result of this fix, replication of multi-table updates no
     longer fails when an update references a missing table but does
     not update any of its columns.  (Bug#37051
     (http://bugs.mysql.com/37051))

   * *Replication*: Performing an insert on a table having an
     `AUTO_INCREMENT' column and an *Note `INSERT': insert. trigger
     that was being replicated from a master running MySQL 5.0 or any
     version of MySQL 5.1 up to and including MySQL 5.1.11 to a slave
     running MySQL 5.1.12 or later caused the replication slave to
     crash.  (Bug#36443 (http://bugs.mysql.com/36443)) See also
     Bug#33029 (http://bugs.mysql.com/33029).

   * Multiple concurrent inserts to a `Maria' table could lead to a
     deadlock situation.  (Bug#39363 (http://bugs.mysql.com/39363))

   * When renaming a `Falcon' table the corresponding indexes could
     become corrupt or unavailable.  (Bug#39354
     (http://bugs.mysql.com/39354))

   * When performing an online `DROP INDEX' on a `Falcon' table, the
     operation may conflict with other index operations such as
     including index scans. When one client drops an index, another
     client may initiate a concurrent index operation that accesses the
     mapping object of the index being dropped, and this can cause a
     crash.  (Bug#39349 (http://bugs.mysql.com/39349), Bug#39350
     (http://bugs.mysql.com/39350), Bug#39845
     (http://bugs.mysql.com/39845), Bug#39846
     (http://bugs.mysql.com/39846))

   * Explicitly running an online index operation on a `Falcon' table
     using `ALTER ONLINE TABLE ...' would fail with an error specifying
     that the specified operation was not supported.  (Bug#39347
     (http://bugs.mysql.com/39347))

   * Running `LOAD DATA INFILE' on a large source data into a `Falcon'
     table with millions of rows, a crash could occur.  (Bug#39296
     (http://bugs.mysql.com/39296))

   * Compiling `Falcon' on Solaris SPARC or x86 using the Sun Studio 12
     compiler would lead to exceptions being disabled. Exceptions are
     required by Falcon and the build and binary would ultimately fail
     during execution.  (Bug#39241 (http://bugs.mysql.com/39241))

   * Host name lookup failure could lead to a server crash.  (Bug#39153
     (http://bugs.mysql.com/39153))

   * When recovering from a serial log containing many `CREATE
     TABLESPACE' and `DROP TABLESPACE' statements, `Falcon' could lose
     data from tablespaces not referenced by these statements.
     (Bug#39138 (http://bugs.mysql.com/39138)) See also Bug#39789
     (http://bugs.mysql.com/39789).

   * When specifying an alternative log directory for `FALCON' using
     `serial_log_directory' the operation would fail silently if the
     directory did not exist. MySQL will now fail to start if the
     serial log in the specified directory cannot be opened or created,
     or if the `falcon_master.fts' cannot be opened or created.
     (Bug#39098 (http://bugs.mysql.com/39098), Bug#38377
     (http://bugs.mysql.com/38377))

   * `Falcon' key pages were written to the serial log in the wrong
     order. This had the potential to cause problems if a failure of
     the server occurred during recovery.  (Bug#39025
     (http://bugs.mysql.com/39025))

   * `Falcon' could hang trying to perform an *Note `UPDATE': update.
     in one transaction while waiting for another transaction to be
     committed or rolled back.  (Bug#38947
     (http://bugs.mysql.com/38947))

   * It was not possible to build the server with `Falcon' support on
     SPARC when using the Sun Studio compiler.  (Bug#38891
     (http://bugs.mysql.com/38891))

   * On Solaris platforms, when the server was built with `Falcon'
     support and the data directory set in user's home directory, *Note
     `mysql_install_db': mysql-install-db.  failed.  (Bug#38843
     (http://bugs.mysql.com/38843))

   * `Falcon' did not honor the `--datadir' option and created its
     files in the current directory instead. This error was apparent
     only when running the embedded version of MySQL.  (Bug#38770
     (http://bugs.mysql.com/38770))

   * When built with `Falcon' support on 64-bit SPARC platforms, *Note
     `mysqld': mysqld. hung on startup. This occurred whether Sun
     Studio or `gcc' was used to compile the server.  (Bug#38766
     (http://bugs.mysql.com/38766))

   * `Falcon' did not build on Linux with Valgrind enabled.  (Bug#38746
     (http://bugs.mysql.com/38746))

   * Performing a `DELETE' on a `Maria' table where the table has been
     locked using `LOCK TABLE ... WRITE CONCURRENT' would result in an
     assertion failure.  (Bug#38606 (http://bugs.mysql.com/38606))

   * When using *Note `mysql_install_db': mysql-install-db. on MySQL
     built with Sun Studio 12 with the `--with-debug' option enabled,
     the server would crash.  (Bug#38594 (http://bugs.mysql.com/38594))

   * Server-side cursors were not initialized properly, which could
     cause a server crash.  (Bug#38486 (http://bugs.mysql.com/38486))

   * A server crash or Valgrind warnings could result when a stored
     procedure selected from a view that referenced a function.
     (Bug#38291 (http://bugs.mysql.com/38291))

   * A failure to clean up binary log events was corrected (detected by
     Valgrind).  (Bug#38290 (http://bugs.mysql.com/38290))

   * Queries containing a subquery with `DISTINCT' and `ORDER BY' could
     cause a server crash.  (Bug#38191 (http://bugs.mysql.com/38191))

   * `CREATE TABLESPACE' failed when invoked immediately following a
     `DROP TABLESPACE' statement that used the same tablespace name.
     (Bug#38186 (http://bugs.mysql.com/38186), Bug#38743
     (http://bugs.mysql.com/38743))

   * Over-aggressive lock acquisition by `InnoDB' when calculating free
     space for tablespaces could result in performance degradation when
     multiple threads were executing statements on multi-core machines.
     (Bug#38185 (http://bugs.mysql.com/38185))

   * The fix for Bug#20748 (http://bugs.mysql.com/20748) caused a
     problem such that on Unix, MySQL programs looked for options in
     `~/my.cnf' rather than the standard location of `~/.my.cnf'.
     (Bug#38180 (http://bugs.mysql.com/38180))

   * `UUID()' values could have hyphens in the wrong place.  (Bug#38160
     (http://bugs.mysql.com/38160))

   * Queries with a `HAVING' clause could return a spurious row.
     (Bug#38072 (http://bugs.mysql.com/38072))

   * `MyISAM' tables with non-ASCII characters in their names could not
     be backed up because the `MyISAM' native backup driver did not
     handle them properly.  (Bug#38045 (http://bugs.mysql.com/38045))

   * Dropping and re-creating a `Falcon' table, then adding indexes to
     the re-created table, could cause spurious errors or possibly a
     crash of the server.  (Bug#38039 (http://bugs.mysql.com/38039))

   * If the table definition cache contained tables with many *Note
     `BLOB': blob. columns, much memory could be allocated to caching
     *Note `BLOB': blob.  values. Now a size limit on the cached *Note
     `BLOB': blob. values is enforced.  (Bug#38002
     (http://bugs.mysql.com/38002))

   * The server returned incorrect results for `WHERE ... OR ... GROUP
     BY' queries against `InnoDB' tables.  (Bug#37977
     (http://bugs.mysql.com/37977))

   * `SUM(DISTINCT)' and `AVG(DISTINCT)' for an empty result set in a
     subquery were not properly handled as being able to return `NULL'.
     (Bug#37891 (http://bugs.mysql.com/37891))

   * For `InnoDB' tables, `ORDER BY ...  DESC' sometimes returned
     results in ascending order.  (Bug#37830
     (http://bugs.mysql.com/37830))

   * The server returned unexpected results if a right side of the `NOT
     IN' clause consisted of the `NULL' value and some constants of the
     same type. For example, this query might return 3, 4, 5, and so
     forth if a table contained those values:

          SELECT * FROM t WHERE NOT t.id IN (NULL, 1, 2);

     (Bug#37761 (http://bugs.mysql.com/37761))

   * Executing large numbers of SQL statements using `LIMIT' on
     `Falcon' tables eventually led to a crash of the server.
     (Bug#37726 (http://bugs.mysql.com/37726))

   * Setting the session value of the `innodb_table_locks' system
     variable caused a server crash.  (Bug#37669
     (http://bugs.mysql.com/37669))

   * Nesting of `IF()' inside of `SUM()' could cause an extreme server
     slowdown.  (Bug#37662 (http://bugs.mysql.com/37662))

   * For *Note `BACKUP DATABASE': backup-database, if the `WITH
     COMPRESSION' clause was not used, an uninitialized variable could
     cause unpredictable results.  (Bug#37654
     (http://bugs.mysql.com/37654))

   * Killing a query that used an `EXISTS' subquery as the argument to
     `SUM()' or `AVG()' caused a server crash.  (Bug#37627
     (http://bugs.mysql.com/37627))

   * mysqld failed to build using the Sun Studio compiler.  (Bug#37603
     (http://bugs.mysql.com/37603))

   * When using indexed `ORDER BY' sorting, incorrect query results
     could be produced if the optimizer switched from a covering index
     to a non-covering index.  (Bug#37548 (http://bugs.mysql.com/37548))

   * After *Note `TRUNCATE TABLE': truncate. for an `InnoDB' table,
     inserting explicit values into an `AUTO_INCREMENT' column could
     fail to increment the counter and result in a duplicate-key error
     for subsequent insertion of `NULL'.  (Bug#37531
     (http://bugs.mysql.com/37531))

   * For a `MyISAM' table with `CHECKSUM = 1' and `ROW_FORMAT =
     DYNAMIC' table options, a data consistency check (maximum record
     length) could fail and cause the table to be marked as corrupted.
     (Bug#37310 (http://bugs.mysql.com/37310))

   * The `max_length' result set metadata value was calculated
     incorrectly under some circumstances.  (Bug#37301
     (http://bugs.mysql.com/37301))

   * The `optimizer_switch' system variable takes a comma-separated
     list of values, but only the first value in the list was used.
     (Bug#37120 (http://bugs.mysql.com/37120))

   * Executing `ALTER TABLE ADD PARTITION' followed by `ALTER TABLE
     DROP PARTITION' on a Falcon table, and then killing the thread
     performing these statements could cause the server to crash.
     (Bug#37072 (http://bugs.mysql.com/37072))

   * `NOT IN' subqueries that selected `MIN()' or `MAX()' values but
     produced an empty result could cause a server crash.  (Bug#37004
     (http://bugs.mysql.com/37004))

   * A server crash resulted from attempts at semi-join and
     materialization optimizations for subqueries with a parent of
     `SELECT ... FROM DUAL'.  (Bug#36896 (http://bugs.mysql.com/36896))

   * Server crashed when starting a new *Note `BACKUP DATABASE':
     backup-database. or *Note `RESTORE': restore.  statement while a
     *Note `BACKUP DATABASE': backup-database.  or *Note `RESTORE':
     restore. was ongoing.  (Bug#36795 (http://bugs.mysql.com/36795))

   * The `CSV' storage engine returned success even when it failed to
     open a table's data file.  (Bug#36638
     (http://bugs.mysql.com/36638))

   * `SELECT DISTINCT' from a simple view on an `InnoDB' table, where
     all selected columns belong to the same unique index key, returned
     incorrect results.  (Bug#36632 (http://bugs.mysql.com/36632))

   * *Note `RESTORE': restore. could fail if the server on which the
     restore operation took place had enabled triggers or events.
     (Bug#36530 (http://bugs.mysql.com/36530))

   * The parser incorrectly allowed MySQL error code 0 to be specified
     for a condition handler. (This is incorrect because the condition
     must be a failure condition and 0 indicates success.)  (Bug#36510
     (http://bugs.mysql.com/36510))

   * `CHAR(256 USING utf32)' could generate a result with an incorrect
     length and result in a server crash.  (Bug#36418
     (http://bugs.mysql.com/36418))

   * If initialization of an `INFORMATION_SCHEMA' plugin failed, *Note
     `INSTALL PLUGIN': install-plugin.  freed some internal plugin data
     twice.  (Bug#36399 (http://bugs.mysql.com/36399))

   * When the fractional part in a multiplication of *Note `DECIMAL':
     numeric-types. values overflowed, the server truncated the first
     operand rather than the longest. Now the server truncates so as to
     produce more precise multiplications.  (Bug#36270
     (http://bugs.mysql.com/36270))

   * The server could crash with an assertion failure (or cause the
     client to get a `Packets out of order' error) when the expected
     query result was that it should terminate with a `Subquery returns
     more than 1 row' error.  (Bug#36135 (http://bugs.mysql.com/36135))

   * Executing *Note `TRUNCATE': truncate. statements with interleaving
     transactions could cause *Note `mysqld': mysqld. to crash.
     (Bug#35991 (http://bugs.mysql.com/35991)) See also Bug#22165
     (http://bugs.mysql.com/22165).

   * When using both an `INSERT BEFORE' trigger to create a row and
     `AFTER INSERT' trigger to delete the same row on a `FALCON' table,
     the record count as reported by `SHOW TABLE STATUS' could get out
     of sync with the actual record contents. This was caused by the
     changes now being correctly updated in the table status
     information.  (Bug#35939 (http://bugs.mysql.com/35939))

   * Multiple threads executing repeated queries on the same `Falcon'
     table led eventually to a crash of the server.  (Bug#35932
     (http://bugs.mysql.com/35932), Bug#36410
     (http://bugs.mysql.com/36410))

   * The `UUID()' function returned UUIDs with the wrong time; this was
     because the offset for the time part in UUIDs was miscalculated.
     (Bug#35848 (http://bugs.mysql.com/35848))

   * The `configure' script did not allow `utf8_hungarian_ci' to be
     specified as the default collation.  (Bug#35808
     (http://bugs.mysql.com/35808))

   * For *Note `CREATE TABLE': create-table, the parser did not enforce
     that parentheses were present in a `CHECK (EXPR)' clause; now it
     does.  The parser did not enforce that `CONSTRAINT [SYMBOL]'
     without a following `CHECK' clause was illegal; now it does.
     (Bug#35578 (http://bugs.mysql.com/35578), Bug#11714
     (http://bugs.mysql.com/11714), Bug#38696
     (http://bugs.mysql.com/38696))

   * Freeing of an internal parser stack during parsing of complex
     stored programs caused a server crash.  (Bug#35577
     (http://bugs.mysql.com/35577), Bug#37269
     (http://bugs.mysql.com/37269), Bug#37228
     (http://bugs.mysql.com/37228))

   * *Note `mysqlbinlog': mysqlbinlog. left temporary files on the disk
     after shutdown, leading to the pollution of the temporary
     directory, which eventually caused *Note `mysqlbinlog':
     mysqlbinlog. to fail. This caused problems in testing and other
     situations where *Note `mysqlbinlog': mysqlbinlog. might be
     invoked many times in a relatively short period of time.
     (Bug#35543 (http://bugs.mysql.com/35543))

   * The code for detecting a byte order mark (BOM) caused *Note
     `mysql': mysql. to crash for empty input.  (Bug#35480
     (http://bugs.mysql.com/35480))

   * Index scans performed with the `sort_union()' access method
     returned wrong results, caused memory to be leaked, and caused
     temporary files to be deleted when the limit set by
     `sort_buffer_size' was reached.  (Bug#35477
     (http://bugs.mysql.com/35477), Bug#35478
     (http://bugs.mysql.com/35478))

   * For uncorrelated subqueries without a `WHERE' clause, use of
     semi-join or materialization options could result in slow
     performance, or use of the LooseScan strategy could produce
     incorrect results.  (Bug#35468 (http://bugs.mysql.com/35468))

   * `CSV' tables with *Note `CHAR': char. columns caused *Note `BACKUP
     DATABASE': backup-database. to produce a server crash.  (Bug#35117
     (http://bugs.mysql.com/35117))

   * If a view depended on a base table that had been dropped, *Note
     `BACKUP DATABASE': backup-database. caused a server crash.
     (Bug#34902 (http://bugs.mysql.com/34902))

   * If a view was altered before backing up a database, *Note `BACKUP
     DATABASE': backup-database. caused a server crash.  (Bug#34867
     (http://bugs.mysql.com/34867))

   * Table checksum calculation could cause a server crash for
     `FEDERATED' tables with *Note `BLOB': blob. columns containing
     `NULL' values.  (Bug#34779 (http://bugs.mysql.com/34779))

   * *Note `BACKUP DATABASE': backup-database. caused a server crash if
     it attempted to back up a view that depended on another view.
     (Bug#34758 (http://bugs.mysql.com/34758), Bug#35347
     (http://bugs.mysql.com/35347))

   * A significant slowdown occurred when many *Note `SELECT': select.
     statements that return many rows from `InnoDB' tables were running
     concurrently.  (Bug#34409 (http://bugs.mysql.com/34409))

   * *Note `mysql_install_db': mysql-install-db. failed if the server
     was running with an SQL mode of `TRADITIONAL'. This program now
     resets the SQL mode internally to avoid this problem.  (Bug#34159
     (http://bugs.mysql.com/34159))

   * Changes to build files were made to enable the MySQL distribution
     to compile on Microsoft Visual C++ Express 2008.  (Bug#33907
     (http://bugs.mysql.com/33907))

   * Fast *Note `ALTER TABLE': alter-table. operations were not fast
     for columns that used multibyte character sets.  (Bug#33873
     (http://bugs.mysql.com/33873))

   * `ORDER BY' failed to take into account accents and lettercases in
     multi-level collations (`latin2_czech_cs' and `cp1250_czech_cs').
     (Bug#33791 (http://bugs.mysql.com/33791), Bug#30462
     (http://bugs.mysql.com/30462))

   * The internal functions `my_getsystime()', `my_micro_time()', and
     `my_micro_time_and_time()' did not work correctly on Windows. One
     symptom was that uniqueness of `UUID()' values could be
     compromised.  (Bug#33748 (http://bugs.mysql.com/33748))

   * The *Note `SHOW FUNCTION CODE': show-function-code. and *Note
     `SHOW PROCEDURE CODE': show-procedure-code. statements are not
     present in non-debug builds, but attempting to use them resulted
     in a `syntax error' message. Now the error message indicates that
     the statements are disabled and that you must use a debug build.
     (Bug#33637 (http://bugs.mysql.com/33637))

   * If a large number of databases were named in the *Note `BACKUP
     DATABASE': backup-database. statement, the server crashed.
     (Bug#33568 (http://bugs.mysql.com/33568))

   * Cached queries that used 256 or more tables were not properly
     cached, so that later query invalidation due to a *Note `TRUNCATE
     TABLE': truncate. for one of the tables caused the server to hang.
     (Bug#33362 (http://bugs.mysql.com/33362))

   * *Note `BACKUP DATABASE': backup-database. did not properly set the
     flags in the first two bytes of the backup image.  (Bug#33120
     (http://bugs.mysql.com/33120))

   * Unindexed `ORDER BY' did not work on short `utf32' columns, or on
     `utf16' columns with a short `max_sort_length' value.  (Bug#33073
     (http://bugs.mysql.com/33073))

   * *Note `BACKUP DATABASE': backup-database. followed by *Note
     `RESTORE': restore. could mangle object names if a non-standard
     charset was used.  (Bug#33023 (http://bugs.mysql.com/33023))

   * After an upgrade to MySQL 6.0.4 or higher, columns that used the
     old 3-byte Unicode `utf8' character set are treated as having the
     `utf8mb3' character set.  *Note `mysql_upgrade': mysql-upgrade.
     did not convert all system tables in the `mysql' database to use
     the new 4-byte Unicode `utf8' character set rather than `utf8mb3'.
     This caused problems such as that the event scheduler would not
     start.  *Note `mysql_upgrade': mysql-upgrade. now performs the
     `utf8mb3' to `utf8' conversion for system tables.  (Bug#33002
     (http://bugs.mysql.com/33002), Bug#33053
     (http://bugs.mysql.com/33053))

   * It was possible to insert invalid Unicode characters (with code
     point values greater than U+10FFFF) into `utf8' and `utf32'
     columns.  (Bug#32914 (http://bugs.mysql.com/32914))

   * *Note `UNION': union. constructs cannot contain `SELECT ... INTO'
     except in the final *Note `SELECT': select. However, if a *Note
     `UNION': union. was used in a subquery and an `INTO' clause
     appeared in the top-level query, the parser interpreted it as
     having appeared in the *Note `UNION': union. and raised an error.
     (Bug#32858 (http://bugs.mysql.com/32858))

   * Inserting `CURRENT_TIME', `CURRENT_DATE', or `CURRENT_TIMESTAMP'
     into a *Note `VARCHAR': char. column didn't work for non-ASCII
     character sets such as `ucs2', `utf16', or `utf32'.  (Bug#32390
     (http://bugs.mysql.com/32390))

   * *Note `mysql_upgrade': mysql-upgrade. attempted to use the `/proc'
     file system even on systems that do not have it.  (Bug#31605
     (http://bugs.mysql.com/31605))

   * *Note `mysql_install_db': mysql-install-db. failed if run with the
     default table type set to `NDB'.  (Bug#31315
     (http://bugs.mysql.com/31315))

   * Making `INFORMATION_SCHEMA' the default database caused the `DROP
     TABLESPACE' statement to be disabled.  (Bug#31302
     (http://bugs.mysql.com/31302))

   * Several MySQL programs could fail if the `HOME' environment
     variable had an empty value.  (Bug#30394
     (http://bugs.mysql.com/30394))

   * The Serbian translation for the `ER_INCORRECT_GLOBAL_LOCAL_VAR'
     error was corrected.  (Bug#29738 (http://bugs.mysql.com/29738))

   * The `BUILD/check-cpu' build script failed if `gcc' had a different
     name (such as `gcc.real' on Debian).  (Bug#27526
     (http://bugs.mysql.com/27526))

   * *Note `ALTER TABLE': alter-table. could not be used to add columns
     to a table if the table had an index on a `utf8' column with a
     *Note `TEXT': blob. data type.  (Bug#26180
     (http://bugs.mysql.com/26180))

   * The XPath `boolean()' function did not cast string and nodeset
     values correctly in some cases. It now returns `TRUE' for any
     non-empty string or nodeset and 0 for a `NULL' string, as specified
     in the XPath standard..  (Bug#26051 (http://bugs.mysql.com/26051))

   * Using *Note `ALTER TABLE': alter-table. with interleaving
     transactions could cause *Note `mysqld': mysqld.  to crash.
     (Bug#22165 (http://bugs.mysql.com/22165))

   * The *Note `FLUSH PRIVILEGES': flush. statement did not produce an
     error when it failed.  (Bug#21226 (http://bugs.mysql.com/21226))

   * After executing a prepared statement that accesses a stored
     function, the next execution would fail to find the function if
     the stored function cache was flushed in the meantime.  (Bug#12093
     (http://bugs.mysql.com/12093), Bug#21294
     (http://bugs.mysql.com/21294))

   * *Note `perror': perror. did not work for errors described in the
     `sql/share/errmsg.txt' file.  (Bug#10143
     (http://bugs.mysql.com/10143))


File: manual.info,  Node: news-6-0-6,  Next: news-6-0-5,  Prev: news-6-0-7,  Up: news-6-0-x

C.1.6 Changes in MySQL 6.0.6 (11 August 2008)
---------------------------------------------

Functionality added or changed:

   * *Important Change*: *Incompatible Change*: The `FEDERATED' storage
     engine is now disabled by default in binary distributions. The
     engine is still available and can be enabled by starting the
     server with the `--federated' option.  (Bug#37069
     (http://bugs.mysql.com/37069))

   * *Incompatible Change*: The `engines' column in the
     `mysql.online_backup' table has been renamed to `drivers' to
     better reflect its contents.  (Bug#34965
     (http://bugs.mysql.com/34965))

   * *Incompatible Change*: A change has been made to the way that the
     server handles prepared statements. This affects prepared
     statements processed at the SQL level (using the *Note `PREPARE':
     prepare. statement) and those processed using the binary
     client-server protocol (using the *Note `mysql_stmt_prepare()':
     mysql-stmt-prepare. C API function).

     Previously, changes to metadata of tables or views referred to in
     a prepared statement could cause a server crash when the statement
     was next executed, or perhaps an error at execute time with a
     crash occurring later. For example, this could happen after
     dropping a table and recreating it with a different definition.

     Now metadata changes to tables or views referred to by prepared
     statements are detected and cause automatic repreparation of the
     statement when it is next executed. Metadata changes occur for DDL
     statements such as those that create, drop, alter, rename, or
     truncate tables, or that analyze, optimize, or repair tables.
     Repreparation also occurs after referenced tables or views are
     flushed from the table definition cache, either implicitly to make
     room for new entries in the cache, or explicitly due to *Note
     `FLUSH TABLES': flush.

     Repreparation is automatic, but to the extent that it occurs,
     performance of prepared statements is diminished.

     Table content changes (for example, with *Note `INSERT': insert. or
     *Note `UPDATE': update.) do not cause repreparation, nor do *Note
     `SELECT': select.  statements.

     An incompatibility with previous versions of MySQL is that a
     prepared statement may now return a different set of columns or
     different column types from one execution to the next. For
     example, if the prepared statement is `SELECT * FROM t1', altering
     `t1' to contain a different number of columns causes the next
     execution to return a number of columns different from the
     previous execution.

     Older versions of the client library cannot handle this change in
     behavior. For applications that use prepared statements with the
     new server, an upgrade to the new client library is strongly
     recommended.

     Along with this change to statement repreparation, the default
     value of the `table_definition_cache' system variable has been
     increased from 128 to 256. The purpose of this increase is to
     lessen the chance that prepared statements will need repreparation
     due to referred-to tables/views having been flushed from the cache
     to make room for new entries.

     A new status variable, `Com_stmt_reprepare', has been introduced
     to track the number of repreparations.  (Bug#27420
     (http://bugs.mysql.com/27420), Bug#27430
     (http://bugs.mysql.com/27430), Bug#27690
     (http://bugs.mysql.com/27690))

   * *Important Change*: Some changes were made to *Note `CHECK TABLE
     ... FOR UPGRADE': check-table. and *Note `REPAIR TABLE':
     repair-table. with respect to detection and handling of tables
     with incompatible `.frm' files (files created with a different
     version of the MySQL server). These changes also affect *Note
     `mysqlcheck': mysqlcheck. because that program uses *Note `CHECK
     TABLE': check-table. and *Note `REPAIR TABLE': repair-table, and
     thus also *Note `mysql_upgrade': mysql-upgrade. because that
     program invokes *Note `mysqlcheck': mysqlcheck.

        * If your table was created by a different version of the MySQL
          server than the one you are currently running, *Note `CHECK
          TABLE ... FOR UPGRADE': check-table. indicates that the table
          has an `.frm' file with an incompatible version.  In this
          case, the result set returned by *Note `CHECK TABLE':
          check-table. contains a line with a `Msg_type' value of
          `error' and a `Msg_text' value of `Table upgrade required.
          Please do "REPAIR TABLE `TBL_NAME`" to fix it!'

        * *Note `REPAIR TABLE': repair-table. without `USE_FRM'
          upgrades the `.frm' file to the current version.

        * If you use `REPAIR TABLE ...USE_FRM' and your table was
          created by a different version of the MySQL server than the
          one you are currently running, *Note `REPAIR TABLE':
          repair-table. will not attempt to repair the table. In this
          case, the result set returned by *Note `REPAIR TABLE':
          repair-table. contains a line with a `Msg_type' value of
          `error' and a `Msg_text' value of `Failed repairing
          incompatible .FRM file'.

          Previously, use of `REPAIR TABLE ...USE_FRM' with a table
          created by a different version of the MySQL server risked the
          loss of all rows in the table.

     (Bug#36055 (http://bugs.mysql.com/36055))

   * *Important Change*: The `Maria' Storage Engine is now available as
     standard. `Maria' is a crash safe version of `MyISAM'. `Maria'
     supports all of the main functionality of the `MyISAM' engine, but
     includes recovery support (in the event of a system crash), full
     logging (including `CREATE', `DROP', `RENAME', and *Note
     `TRUNCATE': truncate. operations), all `MyISAM' row formats and a
     new `Maria'-specific row format.  `Maria' is documented at *Note
     se-maria::.

   * *Important Note*: When MySQL is built with the `Maria' engine, all
     internal temporary on disk tables will use the `Maria' engine.
     Using `Maria' temporary tables in plkace of `MyISAM' tables should
     result in a performance gain.

   * On Unix, it is now possible for the output file for *Note `BACKUP
     DATABASE': backup-database. to be an existing FIFO.  (Bug#37012
     (http://bugs.mysql.com/37012))

   * *Note `mysql_upgrade': mysql-upgrade. now has a `--tmpdir' option
     to enable the location of temporary files to be specified.
     (Bug#36469 (http://bugs.mysql.com/36469))

   * *Note `mysqldump': mysqldump. now adds the `LOCAL' qualifier to the
     *Note `FLUSH TABLES': flush.  statement that is sent to the server
     when the `--master-data' option is enabled. This prevents the
     *Note `FLUSH TABLES': flush.  statement from replicating to
     slaves, which is disadvantageous because it would cause slaves to
     block while the statement executes.  (Bug#35157
     (http://bugs.mysql.com/35157)) See also Bug#38303
     (http://bugs.mysql.com/38303).

   * The use of the `SQL_CACHE' and `SQL_NO_CACHE' options in *Note
     `SELECT': select. statements now is checked more restrictively: 1)
     Previously, both options could be given in the same statement.
     This is no longer true; only one can be given. 2) Previously,
     these options could be given in *Note `SELECT': select. statements
     that were not at the top-level. This is no longer true; the
     options are disallowed in subqueries (including subqueries in the
     `FROM' clause, and *Note `SELECT': select. statements in unions
     other than the first *Note `SELECT': select.  (Bug#35020
     (http://bugs.mysql.com/35020))

   * MySQL source distributions are now available in Zip format.
     (Bug#27742 (http://bugs.mysql.com/27742))

   * The undocumented, deprecated, and not useful `SHOW COLUMN TYPES'
     statement has been removed.  (Bug#5299
     (http://bugs.mysql.com/5299))

   * The server now supports a Debug Sync facility for thread
     synchronization during testing and debugging. To compile in this
     facility, configure MySQL with the `--enable-debug-sync' option.
     The `debug_sync' system variable provides the user interface Debug
     Sync.  *Note `mysqld': mysqld. and `mysql-test-run.pl' support a
     `--debug-sync-timeout' option to enable the facility and set the
     default synchronization point timeout.

   * `mysql-test-run.pl' now supports a `--mysqltest' option for
     specifying options to the `mysqltest' program.

   * Several improvements were made to MySQL Backup (the *Note `BACKUP
     DATABASE': backup-database. and *Note `RESTORE': restore.
     statements):

        * Drivers are now included for storage engines that do not
          store any data or rely on other storage engines for data
          storage: `MERGE', `FEDERATED', `BLACKHOLE', `EXAMPLE'.

        * The backup kernel better determines the dependency ordering
          of objects to be backed up so that they can be restored in
          the proper order.

        * Restored events and triggers are not reactivated until the
          restore operation completes.

   * *Note `BACKUP DATABASE': backup-database. now has a `WITH
     COMPRESSION' clause. This causes the image file to be compressed,
     which reduces its size. Compression also may result in improved
     backup time by reducing writes to disk.

   * When reading from `FALCON' tables, `FALCON' can take advantage of
     reading from the disk in larger blocks. When enabled, disk reads
     are in blocks of 64KB. When switched off, disk reads are based on
     the page size as set by `falcon_page_size'.

Bugs fixed:

   * *Important Change*: *Security Fix*: Additional corrections were
     made for the symlink-related privilege problem originally
     addressed in MySQL 6.0.5. The original fix did not correctly
     handle the data directory path name if it contained symlinked
     directories in its path, and the check was made only at
     table-creation time, not at table-opening time later.  (Bug#32167
     (http://bugs.mysql.com/32167), CVE-2008-2079
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-2079)) See
     also Bug#39277 (http://bugs.mysql.com/39277).

   * *Incompatible Change*: *Note `SHOW STATUS': show-status. took a
     lot of CPU time for calculating the value of the
     `Innodb_buffer_pool_pages_latched' status variable. Now this
     variable is calculated and included in the output of *Note `SHOW
     STATUS': show-status. only if the `UNIV_DEBUG' symbol is defined
     at MySQL build time.  (Bug#36600 (http://bugs.mysql.com/36600))

   * *Incompatible Change*: Access privileges for several statements
     are more accurately checked:

        * *Note `CHECK TABLE': check-table. requires some privilege for
          the table.

        * *Note `CHECKSUM TABLE': checksum-table. requires `SELECT' for
          the table.

        * `CREATE TABLE ... LIKE' requires `SELECT' for the source table
          and `CREATE' for the destination table.

        * *Note `SHOW COLUMNS': show-columns. displays information only
          for those columns you have some privilege for.

        * *Note `SHOW CREATE TABLE': show-create-table. requires some
          privilege for the table (previously required `SELECT').

        * *Note `SHOW CREATE VIEW': show-create-view. requires `SHOW
          VIEW' and `SELECT' for the view.

        * *Note `SHOW INDEX': show-index. requires some privilege for
          any column.

        * *Note `SHOW OPEN TABLES': show-open-tables. displays only
          tables for which you have some privilege on any table column.

     (Bug#27145 (http://bugs.mysql.com/27145))

   * *Incompatible Change*: Certain characters were sorted incorrectly
     for the following collations: TILDE and GRAVE ACCENT in
     `big5_chinese_ci'; LATIN SMALL LETTER J in `cp866_general_ci';
     TILDE in `gb2312_chinese_ci'; and TILDE in `gbk_chinese_ci'.

     As a result of this fix, any indexes on columns that use these
     collations and contain the affected characters must be rebuilt
     when upgrading to 6.0.6 or higher. To do this, use *Note `ALTER
     TABLE': alter-table. to drop and re-add the indexes, or *Note
     `mysqldump': mysqldump. to dump the affected tables and *Note
     `mysql': mysql. to reload the dump file.  (Bug#25420
     (http://bugs.mysql.com/25420))

   * *Incompatible Change*: An additional correction to the original
     MySQL 6.0.4 fix was made to normalize directory names before
     adding them to the list of directories. This prevents `/etc/' and
     `/etc' from being considered different, for example.  (Bug#20748
     (http://bugs.mysql.com/20748)) See also Bug#38180
     (http://bugs.mysql.com/38180).

   * *Important Change*: Previously, `Falcon' failed silently when
     attempting to read incompatible datafiles created by an earlier
     version of the storage engine. Now, when `Falcon' encounters such
     datafiles, it refuses to start, and an appropriate error is issued
     instead.  (Bug#35190 (http://bugs.mysql.com/35190))

   * *Important Change*: The server no longer issues warnings for
     truncation of excess spaces for values inserted into *Note `CHAR':
     char. columns. This reverts a change in the previous release that
     caused warnings to be issued.  (Bug#30059
     (http://bugs.mysql.com/30059))

   * *Partitioning*: *Important Note*: The statements *Note `ANALYZE
     TABLE': analyze-table, *Note `CHECK TABLE': check-table, *Note
     `OPTIMIZE TABLE': optimize-table, and *Note `REPAIR TABLE':
     repair-table. are now supported for partitioned tables.

     Also as a result of this fix, the following statements which were
     disabled in MySQL 6.0.5 have been re-enabled:

        * `ALTER TABLE ... ANALYZE PARTITION'

        * `ALTER TABLE ... CHECK PARTITION'

        * `ALTER TABLE ... OPTIMIZE PARTITION'

        * `ALTER TABLE ... REPAIR PARTITION'

     (Bug#20129 (http://bugs.mysql.com/20129)) See also Bug#39434
     (http://bugs.mysql.com/39434).

   * *Partitioning*: *Note `myisamchk': myisamchk. failed with an
     assertion error when analyzing a partitioned `MyISAM' table.
     (Bug#37537 (http://bugs.mysql.com/37537))

   * *Partitioning*: When an attempt is made to change a table to an
     unsupported storage engine, the server normally uses the default
     storage engine in place of the requested engine while issuing a
     warning.  However, if the table was partitioned, the same *Note
     `ALTER TABLE': alter-table. statement failed with the error, `The
     mix of handlers in the partitions is not allowed in this version
     of MySQL'. This happened even if the server was not running in
     `NO_ENGINE_SUBSTITUTION' mode.  Now the behavior for partitioned
     tables is the same as for other MySQL tables; the substitution is
     made, and a warning is issued.  (Bug#35765
     (http://bugs.mysql.com/35765))

   * *Partitioning*: `MyISAM' recovery enabled with the
     `--myisam-recover' option did not work for partitioned `MyISAM'
     tables.  (Bug#35161 (http://bugs.mysql.com/35161))

   * *Partitioning*: When one user was in the midst of a transaction on
     a partitioned table, a second user performing an *Note `ALTER
     TABLE': alter-table. on this table caused the server to hang.
     (Bug#34604 (http://bugs.mysql.com/34604))

   * *Partitioning*: Inserts failed on partitioned tables containing
     user-supplied values for an `AUTO_INCREMENT' column.  (Bug#33479
     (http://bugs.mysql.com/33479))

   * *Partitioning*: Partition-level `TABLESPACE' options were ignored
     for `Falcon' tables.  (Bug#33404 (http://bugs.mysql.com/33404))

   * *Partitioning*: For `InnoDB' tables, there was a race condition
     involving the data dictionary and repartitioning.  (Bug#33349
     (http://bugs.mysql.com/33349))

   * *Replication*: *Note `CREATE PROCEDURE': create-procedure. and
     *Note `CREATE FUNCTION': create-function. statements containing
     extended comments were not written to the binary log correctly,
     causing parse errors on the slave.  (Bug#36570
     (http://bugs.mysql.com/36570)) See also Bug#32575
     (http://bugs.mysql.com/32575).

   * *Replication*: When flushing tables, there was a slight chance
     that the flush occurred between the processing of one table map
     event and the next. Since the tables were opened one by one,
     subsequent locking of tables would cause the slave to crash. This
     problem was observed when replicating `NDBCLUSTER' or `InnoDB'
     tables, when executing multi-table updates, and when a trigger or
     a stored routine performed an (additional) insert on a table so
     that two tables were effectively being inserted into in the same
     statement.  (Bug#36197 (http://bugs.mysql.com/36197))

   * *Replication*: *Note `INSTALL PLUGIN': install-plugin. and *Note
     `UNINSTALL PLUGIN': uninstall-plugin. caused row-based replication
     to fail.

     *Note*:

     These statements are not replicated; however, when using row-based
     logging, the changes they introduce in the `mysql' system tables
     are written to the binary log.

     (Bug#35807 (http://bugs.mysql.com/35807))

   * *Replication*: *Note `CREATE VIEW': create-view. statements
     containing extended comments were not written to the binary log
     correctly, causing parse errors on the slave. Now, all comments are
     stripped from such statements before being written to the binary
     log.  (Bug#32575 (http://bugs.mysql.com/32575)) See also Bug#36570
     (http://bugs.mysql.com/36570).

   * The minimum page size accepted by `FALCON' has been increased from
     1K to 2K.  (Bug#39707 (http://bugs.mysql.com/39707))

   * Trying to execute a DDL statement on a `Falcon' table while a
     transaction was being rolled back could cause the server to crash.
     (Bug#38933 (http://bugs.mysql.com/38933))

   * When building `FALCON' using the Sun Studio 12 compiler, a
     requirement for the GNU Standard C++ (`libstdc++') library would
     be added to the build requirements, causing the build to fail.
     (Bug#38556 (http://bugs.mysql.com/38556))

   * The `Falcon' memory manager did not always perform initialization
     of internal objects correctly.  (Bug#38519
     (http://bugs.mysql.com/38519)) See also Bug#38770
     (http://bugs.mysql.com/38770).

   * Disconnecting a session where you have a applied a `WRITE
     CONCURRENT' lock on `Maria' tables would lead to a crash.
     (Bug#38492 (http://bugs.mysql.com/38492))

   * Range queries on a `Maria' table could fail to return the correct
     rows.  (Bug#38466 (http://bugs.mysql.com/38466))

   * The Windows `my-template.ini' template file contained a reference
     to the `myisam_max_extra_sort_file_size'
     (http://dev.mysql.com/doc/refman/4.1/en/server-system-variables.html#sysvar_myisam_max_extra_sort_file_size)
     system variable, which no longer exists, causing the installed
     server to fail upon startup.  (Bug#38371
     (http://bugs.mysql.com/38371))

   * Incorrect handling of aggregate functions when loose index scan
     was used caused a server crash.  (Bug#38195
     (http://bugs.mysql.com/38195))

   * The fix for Bug#33812 (http://bugs.mysql.com/33812) had the side
     effect of causing the *Note `mysql': mysql. client not to be able
     to read some dump files produced with *Note `mysqldump':
     mysqldump. To address this, that fix was reverted.  (Bug#38158
     (http://bugs.mysql.com/38158))

   * The `MyISAM' backup driver was subject to a race condition that
     allowed multiple *Note `RESTORE': restore. operations to occur
     simultaneously. This could result in locking conflicts, incorrect
     entries in the progress tables, or other problems.  (Bug#38108
     (http://bugs.mysql.com/38108))

   * Concurrent adding or dropping of indexes and execution of DML
     statements on a `Falcon' table could cause the server to crash.
     (Bug#38044 (http://bugs.mysql.com/38044))

   * Executing *Note `ALTER TABLE': alter-table. and DML statements
     concurrently on `Falcon' tables could cause the server to hang.
     (Bug#38043 (http://bugs.mysql.com/38043))

   * `ALTER TABLE ... ADD KEY' and `ALTER TABLE ... DROP KEY' were not
     always handled correctly for `Falcon' tables, resulting in spurious
     duplicate key and other errors.  (Bug#38041
     (http://bugs.mysql.com/38041))

   * If a table has a `BIT NOT NULL' column `c1' with a length shorter
     than 8 bits and some additional `NOT NULL' columns `c2', ..., and a
     *Note `SELECT': select. query has a `WHERE' clause of the form
     `(c1 = CONSTANT) AND c2 ...', the query could return an unexpected
     result set.  (Bug#37799 (http://bugs.mysql.com/37799))

   * MySQL server binaries built using `gcc4.3' could crash when
     running large numbers of DML statements on `Falcon' tables.
     (Bug#37725 (http://bugs.mysql.com/37725))

   * When building `FALCON' using the Sun Studio 12 compiler on
     OpenSolaris the build would fail due to a missing header file,
     `Interlock.h'.  (Bug#37679 (http://bugs.mysql.com/37679))

   * Building MySQL with SSL and `Falcon' enabled would lead to a build
     failure.  (Bug#37517 (http://bugs.mysql.com/37517))

   * A large number of updates on a `Falcon' table followed by a query
     of the form `SELECT AVG(INT_NON_KEY_COLUMN) FROM TABLE WHERE
     INT_NON_KEY_COLUMN < CONSTANT GROUP BY INT_KEY_COLUMN LIMIT LIMIT'
     could crash the server.  (Bug#37344 (http://bugs.mysql.com/37344))

   * Queries with complex conditions in the `WHERE' clause on `Falcon'
     tables when `falcon_page_size' was set to a low value could cause
     the server to crash.  (Bug#37343 (http://bugs.mysql.com/37343))

   * Within stored programs or prepared statements, `REGEXP' could
     return incorrect results due to improper initialization.
     (Bug#37337 (http://bugs.mysql.com/37337))

   * When running a concurrent scenario involving transactions, each
     executing a small number of `DELETE' and `UPDATE' operations on a
     small number of records on `FALCON' tables, a deadlock could occur.
     (Bug#37251 (http://bugs.mysql.com/37251))

   * When performing operations on a table in one client while a
     different client is performing a `TRUNCATE' operation on the same
     `FALCON' table a deadlock could be introduced.  (Bug#37080
     (http://bugs.mysql.com/37080))

   * The `falcon_max_transaction_backlog' has been removed. The option
     was originally introduced to ensure that the backlog of
     transactions did not exceed a certain level with the gopher
     thread. `FALCON' now uses multiple gopher threads. The transaction
     backlog is handled internally by `FALCON'.  (Bug#36991
     (http://bugs.mysql.com/36991))

   * The `falcon_initial_allocation' has been removed. The option
     created new tablespace files with the specified size to force
     allocation on disk of specified block of contiguous space. The
     option had little effect on the performance of the tablespace
     files, and has therefore been removed.  (Bug#36990
     (http://bugs.mysql.com/36990))

   * The `falcon_index_chill_threshold' and
     `falcon_record_chill_threshold' options have been modified so that
     the specification for the size can be specified in bytes, and
     support the KB, MB, and GB modifiers.  (Bug#36825
     (http://bugs.mysql.com/36825))

   * The code for the `ut_usectime()' function in `InnoDB' did not
     handle errors from the `gettimeofday()' system call. Now it retries
     `gettimeofday()' several times and updates the value of the
     `Innodb_row_lock_time_max' status variable only if `ut_usectime()'
     was successful.  (Bug#36819 (http://bugs.mysql.com/36819))

   * If the length of a field was 3, internal `InnoDB' to integer type
     conversion didn't work on big-endian machines in the
     `row_search_autoinc_column()' function.  (Bug#36793
     (http://bugs.mysql.com/36793))

   * For a view that referred to a `MyISAM' table, the contents of the
     table could be empty after *Note `BACKUP DATABASE':
     backup-database. followed by *Note `RESTORE': restore.  (Bug#36782
     (http://bugs.mysql.com/36782))

   * Data loss could be caused by attempts to read data from a database
     being restored by a *Note `RESTORE': restore. operation.
     (Bug#36778 (http://bugs.mysql.com/36778))

   * Some warnings were being reported as errors.  (Bug#36777
     (http://bugs.mysql.com/36777))

   * Data loss could be caused by activation of a trigger for a
     `MyISAM' table being restored by a *Note `RESTORE': restore.
     operation.  (Bug#36749 (http://bugs.mysql.com/36749))

   * *Note `mysql_install_db': mysql-install-db. from a
     `Falcon'-enabled build crashed on Solaris/SPARC.  (Bug#36745
     (http://bugs.mysql.com/36745))

   * On Windows 64-bit systems, temporary variables of `long' types
     were used to store `ulong' values, causing key cache
     initialization to receive distorted parameters. The effect was
     that setting `key_buffer_size' to values of 2GB or more caused
     memory exhaustion to due allocation of too much memory.
     (Bug#36705 (http://bugs.mysql.com/36705))

   * Multiple-table *Note `UPDATE': update. statements that used a
     temporary table could fail to update all qualifying rows or fail
     with a spurious duplicate-key error.  (Bug#36676
     (http://bugs.mysql.com/36676))

   * A query which had an `ORDER BY DESC' clause that is satisfied with
     a reverse range scan could cause a server crash for some specific
     CPU/compiler combinations.  (Bug#36639
     (http://bugs.mysql.com/36639))

   * The online backup stream library failed to parse the backup stream
     on 64-bit systems.  (Bug#36624 (http://bugs.mysql.com/36624))

   * `FALCON' would try to open a number of files during startup that
     are not required by the MySQL storage engine implmentation. These
     operations have been removed.  (Bug#36620
     (http://bugs.mysql.com/36620))

   * On 64-bit platforms, *Note `BACKUP DATABASE': backup-database.
     hung for backups of more than 32KB.  (Bug#36586
     (http://bugs.mysql.com/36586))

   * Dumping information about locks in use by sending a `SIGHUP'
     signal to the server or by invoking the *Note `mysqladmin debug':
     mysqladmin. command could lead to a server crash in debug builds
     or to undefined behavior in production builds.  (Bug#36579
     (http://bugs.mysql.com/36579))

   * A `REGEXP' match could return incorrect rows when the previous row
     matched the expression and used `CONCAT()' with an empty string.
     (Bug#36488 (http://bugs.mysql.com/36488))

   * The server could not be compiled with `Falcon' support on
     Solaris/x86.  (Bug#36486 (http://bugs.mysql.com/36486))

   * `mysqltest' ignored the value of `--tmpdir' in one place.
     (Bug#36465 (http://bugs.mysql.com/36465))

   * The `ER_TRUNCATED_WRONG_VALUE' warning condition was sometimes
     raised as an error.  (Bug#36457 (http://bugs.mysql.com/36457))

   * When one MySQL client application committed a transaction
     affecting a `Falcon' table at the same time that another client
     dropped this table, the *Note `DROP TABLE': drop-table. statement
     did not `see' that transaction. This led to a situation such that
     a row affected by the transaction was later accessed in a manner
     that referred to the deleted table, resulting in a crash of the
     server.  (Bug#36438 (http://bugs.mysql.com/36438))

   * `ha_innodb.so' was incorrectly installed in the `lib/mysql'
     directory rather than in `lib/mysql/plugin'.  (Bug#36434
     (http://bugs.mysql.com/36434))

   * Compiling the server with `Falcon' support failed on Solaris 10
     due to problems with DTrace. This occurred even when the build was
     configured using `--disable-dtrace'.  (Bug#36403
     (http://bugs.mysql.com/36403))

   * Compiling the server with `Falcon' support failed on Solaris 10
     for x86 platforms failed due to use of assembler code specific to
     `gcc'.  (Bug#36400 (http://bugs.mysql.com/36400))

   * Dropping a `Falcon' tablespace concurrently with dropping a table
     using that tablespace caused the server to crash.  (Bug#36396
     (http://bugs.mysql.com/36396))

   * Attempting to compile the server with Falcon support using the Sun
     Studio 12 compiler failed with the error `"Value.h", line 185:
     Error: A union member cannot have a user-defined assignment
     operator'.  (Bug#36368 (http://bugs.mysql.com/36368))

   * The default drivers for *Note `BACKUP DATABASE': backup-database.
     and *Note `RESTORE': restore.  now support a cancel operation,
     which also allows better cleanup if a driver error occurs.
     (Bug#36323 (http://bugs.mysql.com/36323))

   * The server crashed while parsing large floating-point numbers such
     as `1e37' or `-1e15'.  (Bug#36320 (http://bugs.mysql.com/36320))

   * When updating an existing instance (for example, from MySQL 5.0 to
     5.1, or 5.1 to 6.0), the Instance Configuration Wizard
     unnecessarily prompted for a `root' password when there was an
     existing `root' password.  (Bug#36305
     (http://bugs.mysql.com/36305))

   * Following a number of *Note `INSERT ... SELECT': insert-select.
     statements on a `Falcon' table, creating a second `Falcon' table
     using the same tablespace as the table into which the inserts were
     made and then performing a simple *Note `INSERT': insert. on the
     new table caused the server to crash.  (Bug#36294
     (http://bugs.mysql.com/36294), Bug#36367
     (http://bugs.mysql.com/36367)) See also Bug#29648
     (http://bugs.mysql.com/29648).

   * For `InnoDB' tables, the `DATA_FREE' column of the *Note
     `INFORMATION_SCHEMA.TABLES': tables-table. displayed free space in
     kilobytes rather than bytes. Now it displays bytes.  (Bug#36278
     (http://bugs.mysql.com/36278))

   * *Note `BACKUP DATABASE': backup-database. failed to back up views
     that depend on tables in a different database.  (Bug#36265
     (http://bugs.mysql.com/36265))

   * The project files created for Windows were missing the `GenError'
     project dependency.  (Bug#36257 (http://bugs.mysql.com/36257))

   * The *Note `mysql': mysql. client failed to recognize comment lines
     consisting of `--' followed by a newline.  (Bug#36244
     (http://bugs.mysql.com/36244))

   * *Note `CREATE INDEX': create-index. for `InnoDB' tables could
     under very rare circumstances cause the server to crash..
     (Bug#36169 (http://bugs.mysql.com/36169))

   * A read past the end of the string could occur while parsing the
     value of the `--innodb-data-file-path' option.  (Bug#36149
     (http://bugs.mysql.com/36149))

   * Conversion of a `FLOAT ZEROFILL' value to string could cause a
     server crash if the value was `NULL'.  (Bug#36139
     (http://bugs.mysql.com/36139))

   * The combination of semi-join and materialization both being
     enabled could lead to assertion failure during subquery processing.
     (Bug#36137 (http://bugs.mysql.com/36137))

   * Range optimizer evaluation of `IN' subqueries to be handled with
     the materialization strategy could lead to assertion failure.
     (Bug#36133 (http://bugs.mysql.com/36133))

   * A server crash could occur during the cleanup phase of subquery
     execution.  (Bug#36128 (http://bugs.mysql.com/36128))

   * On Windows, the installer attempted to use JScript to determine
     whether the target data directory already existed. On Windows
     Vista x64, this resulted in an error because the installer was
     attempting to run the JScript in a 32-bit engine, which wasn't
     registered on Vista. The installer no longer uses JScript but
     instead relies on a native WiX command.  (Bug#36103
     (http://bugs.mysql.com/36103))

   * A `SELECT ... LIKE' query issued following a number of *Note
     `INSERT': insert. statements on a `Falcon' table failed to return
     all matching records.  (Bug#36097 (http://bugs.mysql.com/36097))

   * `mysqltest' was performing escape processing for the
     `--replace_result' command, which it should not have been.
     (Bug#36041 (http://bugs.mysql.com/36041))

   * An error in calculation of the precision of zero-length items
     (such as `NULL') caused a server crash for queries that employed
     temporary tables.  (Bug#36023 (http://bugs.mysql.com/36023))

   * For `EXPLAIN EXTENDED', execution of an uncorrelated `IN' subquery
     caused a crash if the subquery required a temporary table for its
     execution.  (Bug#36011 (http://bugs.mysql.com/36011))

   * The `MERGE' storage engine did a table scan for `SELECT COUNT(*)'
     statements when it could calculate the number of records from the
     underlying tables.  (Bug#36006 (http://bugs.mysql.com/36006))

   * The server crashed inside `NOT IN' subqueries with an impossible
     `WHERE' or `HAVING' clause, such as `NOT IN (SELECT ... FROM t1,
     t2, ... WHERE 0)'.  (Bug#36005 (http://bugs.mysql.com/36005))

   * *Note `mysql_stmt_prepare()': mysql-stmt-prepare. did not reset
     the list of messages (those messages available via *Note `SHOW
     WARNINGS': show-warnings.).  (Bug#36004
     (http://bugs.mysql.com/36004))

   * The Event Scheduler was not designed to work under the embedded
     server. It is now disabled for the embedded server, and the
     `event_scheduler' system variable is not displayed.  (Bug#35997
     (http://bugs.mysql.com/35997))

   * Grouping or ordering of long values in unindexed *Note `BLOB':
     blob. or *Note `TEXT': blob. columns with the `gbk' or `big5'
     character set crashed the server.  (Bug#35993
     (http://bugs.mysql.com/35993))

   * `SET GLOBAL debug=''' resulted in a Valgrind warning in
     `DbugParse()', which was reading beyond the end of the control
     string.  (Bug#35986 (http://bugs.mysql.com/35986))

   * If a *Note `SELECT': select. table list contained at least one
     `INFORMATION_SCHEMA' table, the required privileges for accessing
     the other tables were reduced.  (Bug#35955
     (http://bugs.mysql.com/35955))

   * Some syntactically invalid statements could cause the server to
     return an error message containing garbage characters.  (Bug#35936
     (http://bugs.mysql.com/35936))

   * MySQL could not be built using Sun Studio due to the use of
     compiler options specific to `gcc'.  (Bug#35929
     (http://bugs.mysql.com/35929))

   * The `prefer full scan on clustered primary key over full scan of
     any secondary key' optimizer rule introduced by Bug#26447
     (http://bugs.mysql.com/26447) caused a performance regression for
     some queries, so it has been disabled.  (Bug#35850
     (http://bugs.mysql.com/35850))

   * The server ignored any covering index used for `ref' access of a
     table in a query with `ORDER BY' if this index was incompatible
     with the `ORDER BY' list and there was another covering index
     compatible with this list. As a result, suboptimal execution plans
     were chosen for some queries that used an `ORDER BY' clause.
     (Bug#35844 (http://bugs.mysql.com/35844))

   * *Note `mysql_upgrade': mysql-upgrade. did not properly update the
     `mysql.event' table.  (Bug#35824 (http://bugs.mysql.com/35824))

   * The current system time (as returned by `NOW()' or synonyms) became
     constant after a *Note `RESTORE': restore.  operation.  (Bug#35806
     (http://bugs.mysql.com/35806))

   * Processing of an uncorrelated subquery using semi-join could cause
     incorrect results or a server crash.  (Bug#35767
     (http://bugs.mysql.com/35767))

   * An incorrect error and message was produced for attempts to create
     a `MyISAM' table with an index (`.MYI') file name that was already
     in use by some other `MyISAM' table that was open at the same
     time. For example, this might happen if you use the same value of
     the `INDEX DIRECTORY' table option for tables belonging to
     different databases.  (Bug#35733 (http://bugs.mysql.com/35733))

   * Enabling the `read_only' system variable while autocommit mode was
     enabled caused *Note `SELECT': select. statements for
     transactional storage engines to fail.  (Bug#35732
     (http://bugs.mysql.com/35732))

   * The range optimizer ignored conditions on inner tables in
     semi-join `IN' subqueries, causing the optimizer to miss good
     query execution plans.  (Bug#35674 (http://bugs.mysql.com/35674))

   * An empty bit-string literal (`b''') caused a server crash. Now the
     value is parsed as an empty bit value (which is treated as an
     empty string in string context or 0 in numeric context).
     (Bug#35658 (http://bugs.mysql.com/35658))

   * On 64-bit systems, assigning values of 2 ^63 - 1 or larger to
     `key_buffer_size' caused memory overruns.  (Bug#35616
     (http://bugs.mysql.com/35616))

   * For `InnoDB' tables, *Note `REPLACE': replace. statements used
     `traditional' style locking, regardless of the setting of
     `innodb_autoinc_lock_mode'. Now *Note `REPLACE': replace. works
     the same way as `simple inserts' instead of using the old locking
     algorithm. (*Note `REPLACE': replace. statements are treated in
     the same way as as *Note `INSERT': insert. statements.)
     (Bug#35602 (http://bugs.mysql.com/35602))

   * Different invocations of *Note `CHECKSUM TABLE': checksum-table.
     could return different results for a table containing columns with
     spatial data types.  (Bug#35570 (http://bugs.mysql.com/35570))

   * A semi-join subquery in the `ON' clause in the absence of a
     `WHERE' clause caused a server crash.  (Bug#35550
     (http://bugs.mysql.com/35550))

   * `InnoDB' was not updating the `Handler_delete' or `Handler_update'
     status variables.  (Bug#35537 (http://bugs.mysql.com/35537))

   * The method for enumerating view dependencies could cause the
     server to deadlock.  (Bug#35395 (http://bugs.mysql.com/35395))

   * If the server crashed with an `InnoDB' error due to unavailability
     of undo slots, errors could persist during rollback when the
     server was restarted: There are two `UNDO' slot caches (for *Note
     `INSERT': insert. and *Note `UPDATE': update.). If all slots end
     up in one of the slot caches, a request for a slot from the other
     slot cache would fail. This can happen if the request is for an
     *Note `UPDATE': update. slot and all slots are in the *Note
     `INSERT': insert. slot cache, or vice versa.  (Bug#35352
     (http://bugs.mysql.com/35352))

   * Simultaneous inserts and updates on an updateable view referencing
     a `Falcon' table could sometimes cause duplicate key errors.
     (Bug#35322 (http://bugs.mysql.com/35322))

   * The combination of `GROUP_CONCAT()', `DISTINCT', and `LEFT JOIN'
     could crash the server when the right table is empty.  (Bug#35298
     (http://bugs.mysql.com/35298))

   * Accessing a `MERGE' table with an empty underlying table list
     incorrectly resulted in a `wrong index' error message rather than
     `end of file.' (Bug#35274 (http://bugs.mysql.com/35274))

   * *Note `BACKUP DATABASE': backup-database. caused a server crash
     upon encountering a table row that has been marked for deletion
     but not removed.  (Bug#35249 (http://bugs.mysql.com/35249))

   * For `InnoDB' tables, `ALTER TABLE DROP' failed if the name of the
     column to be dropped began with `foreign'.  (Bug#35220
     (http://bugs.mysql.com/35220))

   * The table pullout strategy was not reflected in `EXPLAIN EXTENDED'
     output if not all of the subquery tables were pulled out.
     (Bug#35160 (http://bugs.mysql.com/35160))

   * Access-denied messages for `INFORMATION_SCHEMA' incorrectly showed
     the name of the default database instead.  (Bug#35096
     (http://bugs.mysql.com/35096))

   * Passing an invalid parameter to `CHAR()' in an `ORDER BY' clause
     caused the server to hang.  (Bug#34949
     (http://bugs.mysql.com/34949))

   * Some binaries produced stack corruption messages due to being
     built with versions of `bison' older than 2.1.  Builds are now
     created using `bison' 2.3.  (Bug#34926
     (http://bugs.mysql.com/34926))

   * Concurrent execution of *Note `FLUSH TABLES': flush.  along with
     *Note `SHOW FUNCTION STATUS': show-function-status.  or *Note
     `SHOW PROCEDURE STATUS': show-procedure-status. could cause a
     server crash.  (Bug#34895 (http://bugs.mysql.com/34895))

   * Creating a new `Falcon' table using `CREATE TABLE ... SELECT'
     where the table uses a primary key, and rows contain duplicate
     keys, could lead to a table being created but not populated.
     Because the pending (bad) record was not committed, the table
     remains in a state that means it cannot be dropped or recreated.
     (Bug#34892 (http://bugs.mysql.com/34892))

   * The `log_output' system variable could be set to an illegal value.
     (Bug#34820 (http://bugs.mysql.com/34820))

   * A server crash or memory overrun could occur with a dependent
     subquery and joins.  (Bug#34799 (http://bugs.mysql.com/34799))

   * An assertion could be raised when the dependencies on a
     transaction could not be released after a specified time when
     using `FALCON' tables.  (Bug#34602 (http://bugs.mysql.com/34602))

   * `InnoDB' could crash if overflow occurred for an `AUTO_INCREMENT'
     column.  (Bug#34335 (http://bugs.mysql.com/34335))

   * On Windows 64-bit builds, an apparent compiler bug caused memory
     overruns for code in `innobase/mem/*'.  Removed optimizations so
     as not to trigger this problem.  (Bug#34297
     (http://bugs.mysql.com/34297))

   * Several additional configuration scripts in the `BUILD' directory
     now are included in source distributions. These may be useful for
     users who wish to build MySQL from source. (See *Note
     installing-source-tree::, for information about what they do.)
     (Bug#34291 (http://bugs.mysql.com/34291))

   * For `InnoDB' tables, loss of data resulted from performing inserts
     concurrently with a *Note `RESTORE': restore. operation.
     (Bug#34210 (http://bugs.mysql.com/34210))

   * In some cases, concurrent *Note `INSERT': insert.  and *Note
     `DELETE': delete. statements on the same `Falcon' table could
     cause the server to crash, due to a failure to find a record that
     should have been in the table.  (Bug#33933
     (http://bugs.mysql.com/33933))

   * A number of problems in new subquery optimization code meant that
     MySQL could pick an incorrect query plan when using InsideOut
     and/or FirstMatch subquery optimizations, which in turn would
     cause wrong query results.  (Bug#33743
     (http://bugs.mysql.com/33743))

   * If *Note `CREATE TABLE': create-table. or *Note `ALTER TABLE':
     alter-table. of a `Falcon' table failed, it was not possible to
     create another table in the same database having the same name
     unless the server was restarted. In some cases, subsequent *Note
     `CREATE TABLE': create-table. statements could cause the server to
     crash.  (Bug#33723 (http://bugs.mysql.com/33723))

   * Attempts to access a `FEDERATED' table using a non-existent server
     did not reliably return a proper error.  (Bug#33702
     (http://bugs.mysql.com/33702))

   * It was possible for multiple *Note `mysqld': mysqld. instances to
     use the same `Falcon' tablespace and metadata files, which could
     lead to corruption of the tablespace files, metadata files, or
     both.  (Bug#33607 (http://bugs.mysql.com/33607))

   * *Note `TIMESTAMP': datetime. columns were restored to the current
     date and time (not their actual values) by a *Note `RESTORE':
     restore. operation.  (Bug#33573 (http://bugs.mysql.com/33573))

   * Use of 61 nested subqueries caused a server crash.  (Bug#33509
     (http://bugs.mysql.com/33509))

   * An `ALTER TABLE ... TABLESPACE' statement referencing a
     non-existant tablespace on a `Falcon' table failed with an
     inappropriate error message the first time it was executed. A
     second attempt to execute the statement led to a crash of the
     MySQL server.  (Bug#33397 (http://bugs.mysql.com/33397))

   * Executing a *Note `FLUSH PRIVILEGES': flush. statement after
     creating a temporary table in the `mysql' database with the same
     name as one of the MySQL system tables caused the server to crash.

     *Note*:

     While it is possible to shadow a system table in this way, the
     temporary table exists only for the current user and connection,
     and does not effect any user privileges.

     (Bug#33275 (http://bugs.mysql.com/33275))

   * Selecting from a view that referenced the same table in the `FROM'
     clause and an `IN' clause caused a server crash.  (Bug#33245
     (http://bugs.mysql.com/33245))

   * When creating a new tablespace and specifying the name of an
     existing tablespace file, an incorrect error message would be
     reported specifying that the tablespace already existed. The error
     message has been updated to reflect the actual error.  (Bug#33213
     (http://bugs.mysql.com/33213))

   * There was a race condition between the event scheduler and the
     server shutdown thread.  (Bug#32771 (http://bugs.mysql.com/32771))

   * Assignment of relative path names to `general_log_file' or
     `slow_query_log_file' did not always work.  (Bug#32748
     (http://bugs.mysql.com/32748))

   * Deeply nested subqueries could cause stack overflow or a server
     crash.  (Bug#32680 (http://bugs.mysql.com/32680))

   * Query results from a `FEDERATED' table were corrupt if the query
     included an `ORDER BY' on a *Note `TEXT': blob. column.
     (Bug#32426 (http://bugs.mysql.com/32426))

   * Conversion of binary values to multi-byte character sets could
     fail to left-pad values to the correct length. This could result
     in a server crash.  (Bug#32394 (http://bugs.mysql.com/32394))

   * On all x86 platforms, the default was to attempt to build the
     server with the `Falcon' storage engine, even if `Falcon' was not
     supported for a given platform.  (Bug#32287
     (http://bugs.mysql.com/32287))

   * Killing a statement that invoked a stored function could return an
     incorrect error message indicating table corruption rather than
     that the statement had been interrupted.  (Bug#32140
     (http://bugs.mysql.com/32140))

   * Occurrence of an error within a stored routine did not always
     cause immediate statement termination.  (Bug#31881
     (http://bugs.mysql.com/31881))

   * For `DROP FUNCTION DB_NAME.FUNC_NAME' (that is, when the function
     name is qualified with the database name), the statement should
     apply only to a stored function named `func_name' in the given
     database.  However, if a UDF with the same name existed, the
     statement dropped the UDF instead.  (Bug#31767
     (http://bugs.mysql.com/31767))

   * On NetWare, *Note `mysql_install_db': mysql-install-db. could
     appear to execute normally even if it failed to create the initial
     databases.  (Bug#30129 (http://bugs.mysql.com/30129))

   * A problem related to HP-UX compilers that caused incorrect
     `WEIGHT_STRING()' results was fixed.  (Bug#29825
     (http://bugs.mysql.com/29825))

   * *Note `TRUNCATE TABLE': truncate. for `InnoDB' tables returned a
     count showing too many rows affected. Now the statement returns 0
     for `InnoDB' tables.  (Bug#29507 (http://bugs.mysql.com/29507))

   * `InnoDB' could return an incorrect rows-updated value for *Note
     `UPDATE': update. statements.  (Bug#29157
     (http://bugs.mysql.com/29157))

   * The `mysql.servers' table was not created during installation on
     Windows.  (Bug#28680 (http://bugs.mysql.com/28680), Bug#32797
     (http://bugs.mysql.com/32797))

   * The `jp' test suite was not working.  (Bug#28563
     (http://bugs.mysql.com/28563))

   * The internal `init_time()' library function was renamed to
     `my_init_time()' to avoid conflicts with external libraries.
     (Bug#26294 (http://bugs.mysql.com/26294))

   * In some cases, the parser interpreted the `;' character as the end
     of input and misinterpreted stored program definitions.
     (Bug#26030 (http://bugs.mysql.com/26030))

   * Statements to create, alter, or drop a view were not waiting for
     completion of statements that were using the view, which led to
     incorrect sequences of statements in the binary log when
     statement-based logging was enabled.  (Bug#25144
     (http://bugs.mysql.com/25144))

   * The `Questions' status variable is intended as a count of
     statements sent by clients to the server, but was also counting
     statements executed within stored routines.  (Bug#24289
     (http://bugs.mysql.com/24289))

   * `InnoDB' exhibited thread thrashing with more than 50 concurrent
     connections under an update-intensive workload.  (Bug#22868
     (http://bugs.mysql.com/22868))

   * *Note `DROP DATABASE': drop-database. did not drop orphaned
     `FOREIGN KEY' constraints.  (Bug#18942
     (http://bugs.mysql.com/18942))

   * Delayed-insert threads were counted as connected but not as
     created, incorrectly leading to a `Threads_connected' value
     greater than the `Threads_created' value.  (Bug#17954
     (http://bugs.mysql.com/17954))

   * The parser used signed rather than unsigned values in some cases
     that caused legal lengths in column declarations to be rejected.
     (Bug#15776 (http://bugs.mysql.com/15776))

   * Stored procedure exception handlers were catching fatal errors
     (such as out of memory errors), which could cause execution not to
     stop to due a continue handler. Now fatal errors are not caught by
     exception handlers and a fatal error is returned to the client.
     (Bug#15192 (http://bugs.mysql.com/15192))

   * On Windows, moving an `InnoDB' `.ibd' file and then symlinking to
     it in the database directory using a `.sym' file caused a server
     crash.  (Bug#11894 (http://bugs.mysql.com/11894))

   * If a connection was waiting for a `GET_LOCK()' lock or a `SLEEP()'
     call, and the connection aborted, the server did not detect this
     and thus did not close the connection. This caused a waste of
     system resources allocated to dead connections. Now the server
     checks such a connection every five seconds to see whether it has
     been aborted. If so, the connection is killed (and any lock request
     is aborted).  (Bug#10374 (http://bugs.mysql.com/10374))


File: manual.info,  Node: news-6-0-5,  Next: news-6-0-4,  Prev: news-6-0-6,  Up: news-6-0-x

C.1.7 Changes in MySQL 6.0.5 (12 June 2008)
-------------------------------------------

Functionality added or changed:

   * *Incompatible Change*: In MySQL 5.1.6, when log tables were
     implemented, the default log destination for the general query and
     slow query log was `TABLE'. This default has been changed to
     `FILE', which is compatible with MySQL 5.0, but incompatible with
     earlier releases of MySQL 5.1 from 5.1.6 to 5.1.20. If you are
     upgrading from MySQL 5.0 to this release, no logging option
     changes should be necessary. However, if you are upgrading from
     5.1.6 through 5.1.20 to this release and were using `TABLE'
     logging, use the `--log-output=TABLE' option explicitly to
     preserve your server's table-logging behavior.

     In MySQL 5.1.x, this bug was addressed twice because it turned out
     that the default was set in two places, only one of which was
     fixed the first time.  (Bug#29993 (http://bugs.mysql.com/29993))

   * *Incompatible Change*: The server now includes `dtoa', a library
     for conversion between strings and numbers by David M. Gay. In
     MySQL, this library provides the basis for improved conversion
     between string or *Note `DECIMAL': numeric-types. values and
     approximate-value (*Note `FLOAT': numeric-types./*Note `DOUBLE':
     numeric-types.)  numbers:

        * Consistent conversion results across platforms, which
          eliminates, for example, Unix versus Windows conversion
          differences.

        * Accurate representation of values in cases where results
          previously did not provide sufficient precision, such as for
          values close to IEEE limits.

        * Conversion of numbers to string format with the best possible
          precision. The precision of `dtoa' is always the same or
          bettter than that of the standard C library functions.

     Because the conversions produced by this library differ in some
     cases from previous results, the potential exists for
     incompatibilities in applications that rely on previous results.
     For example, applications that depend on a specific exact result
     from previous conversions might need adjustment to accommodate
     additional precision.

     For additional information about the properties of `dtoa'
     conversions, see *Note type-conversion::.

     See also Bug#12860 (http://bugs.mysql.com/12860), Bug#21497
     (http://bugs.mysql.com/21497), Bug#26788
     (http://bugs.mysql.com/26788), Bug#24541
     (http://bugs.mysql.com/24541), Bug#34015
     (http://bugs.mysql.com/34015).

   * *Important Change*: *MySQL Cluster*: *Packaging*: Beginning with
     this release, standard MySQL 6.0 binaries are no longer built with
     support for the `NDBCLUSTER' storage engine, and the `NDBCLUSTER'
     code included in 6.0 mainline sources is no longer guaranteed to
     be maintained or supported. Those using MySQL Cluster in MySQL
     6.0.4 and earlier MySQL 6.0 mainline releases should upgrade to
     MySQL Cluster NDB 6.2.15 or a later MySQL Cluster NDB 6.2 or 6.3
     release.  (Bug#36193 (http://bugs.mysql.com/36193))

   * *Important Change*: Added a `ROUTINE_TYPE' column to the *Note
     `INFORMATION_SCHEMA.PARAMETERS': parameters-table.  table, to make
     it possible to distinguish like-named parameters of stored
     routines and stored functions having the same names.  See *Note
     parameters-table::, for more information.  (Bug#33106
     (http://bugs.mysql.com/33106))

   * *Replication*: Introduced the `slave_exec_mode'
     (http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_exec_mode)
     system variable to control whether idempotent or strict mode is
     used for replication conflict resolution. Idempotent mode
     suppresses duplicate-key, no-key-found, and some other errors, and
     is needed for circular replication, multi-master replication, and
     some other complex replication setups when using MySQL Cluster.
     Strict mode is the default.  (Bug#31609
     (http://bugs.mysql.com/31609))

   * *Replication*: When running the server with
     `--binlog-format=MIXED' or `--binlog-format=STATEMENT', a query
     that referred to a system variable used the slave's value when
     replayed on the slave. This meant that, if the value of a system
     variable was inserted into a table, the slave differed from the
     master. Now, statements that refer to a system variable are marked
     as `unsafe', which means that:

        * When the server is using `--binlog-format=MIXED', the
          row-based format is used automatically to replicate these
          statements.

        * When the server is using `--binlog-format=STATEMENT', these
          statements produce a warning.

     (Bug#31168 (http://bugs.mysql.com/31168)) See also Bug#34732
     (http://bugs.mysql.com/34732).

   * In the `INFORMATION_SCHEMA' database, the `FALCON_DATABASE_IO'
     table was renamed to `FALCON_TABLESPACE_IO'.  (Bug#35490
     (http://bugs.mysql.com/35490))

   * For boolean options, the option-processing library now prints
     additional information in the `--help' message: If the option is
     enabled by default, the message says so and indicates that the
     `--skip' form of the option disables the option. This affects all
     compiled MySQL programs that use the library.  (Bug#35224
     (http://bugs.mysql.com/35224))

   * The `PROCESS' privilege now is required to start or stop the
     `InnoDB' monitor tables (see *Note innodb-monitors::). Previously,
     no privilege was required.  (Bug#34053
     (http://bugs.mysql.com/34053))

   * For binary `.tar.gz' packages, *Note `mysqld': mysqld. and other
     binaries now are compiled with debugging symbols included to
     enable easier use with a debugger. If you do not need debugging
     symbols and are short on disk space, you can use `strip' to remove
     the symbols from the binaries.  (Bug#33252
     (http://bugs.mysql.com/33252))

   * Several undocumented C API functions were removed:
     `mysql_manager_close()', `mysql_manager_command()',
     `mysql_manager_connect()', `mysql_manager_fetch_line()', and
     `mysql_manager_init()'.  (Bug#31954 (http://bugs.mysql.com/31954))

   * The C API contained several undocumented functions that have been
     removed: `mysql_disable_reads_from_master()',
     `mysql_disable_rpl_parse()', `mysql_enable_reads_from_master()',
     `mysql_enable_rpl_parse()', `mysql_master_query()',
     `mysql_master_send_query()', `mysql_reads_from_master_enabled()',
     `mysql_rpl_parse_enabled()', `mysql_rpl_probe()',
     `mysql_rpl_query_type()', `mysql_set_master()',
     `mysql_slave_query()', and `mysql_slave_send_query()'.  (Bug#31952
     (http://bugs.mysql.com/31952))

   * Formerly, when the MySQL server crashed, the generated stack dump
     was numeric and required external tools to properly resolve the
     names of functions. This is not very helpful to users having a
     limited knowledge of debugging techniques. In addition, the
     generated stack trace contained only the names of functions and
     was formatted differently for each platform due to different stack
     layouts.

     Now it is possible to take advantage of newer versions of the GNU
     C Library provide a set of functions to obtain and manipulate
     stack traces from within the program. On systems that use the ELF
     binary format, the stack trace contains important information such
     as the shared object where the call was generated, an offset into
     the function, and the actual return address. Having the function
     name also makes possible the name demangling of C++ functions.

     The library generates meaningful stack traces on the following
     platforms: i386, x86_64, PowerPC, IA64, Alpha, and S390. On other
     platforms, a numeric stack trace is still produced, and the use of
     the *Note `resolve_stack_dump': resolve-stack-dump. utility is
     still required.  (Bug#31891 (http://bugs.mysql.com/31891))

   * `mysqltest' now has `mkdir' and `rmdir' commands for creating and
     removing directories.  (Bug#31004 (http://bugs.mysql.com/31004))

   * The `LAST_EXECUTED' column of the *Note
     `INFORMATION_SCHEMA.EVENTS': events-table. table now indicates
     when the event started executing rather than when it finished
     executing. As a result, the `ENDS' column is never less than
     `LAST_EXECUTED'.  (Bug#29830 (http://bugs.mysql.com/29830))

   * The `mysql_odbc_escape_string()' C API function has been removed.
     It has multi-byte character escaping issues, doesn't honor the
     `NO_BACKSLASH_ESCAPES' SQL mode and is not needed anymore by
     Connector/ODBC as of 3.51.17.  (Bug#29592
     (http://bugs.mysql.com/29592))

   * The server uses less memory when loading privileges containing
     table grants. (Patch provided by Google.)  (Bug#25175
     (http://bugs.mysql.com/25175))

   * Added the `Uptime_since_flush_status' status variable, which
     indicates the number of seconds since the most recent `FLUSH
     STATUS' statement.  (Community contribution by Jeremy Cole)
     (Bug#24822 (http://bugs.mysql.com/24822))

   * Added the *Note `SHOW PROFILES': show-profiles. and *Note `SHOW
     PROFILE': show-profile. statements to display statement profile
     data, and the accompanying *Note `INFORMATION_SCHEMA.PROFILING':
     profiling-table. table.  Profiling is controlled via the
     `profiling' and `profiling_history_size' session variables. see
     *Note show-profiles::, and *Note profiling-table::. (Community
     contribution by Jeremy Cole)

     The profiling feature is enabled via the
     `--enable-community-features' and `--enable-profiling' options to
     `configure'. These options are enabled by default; to disable
     them, use `--disable-community-features' and `--disable-profiling'.
     (Bug#24795 (http://bugs.mysql.com/24795))

   * The performance of internal functions that trim multiple spaces
     from strings when comparing them has been improved.  (Bug#14637
     (http://bugs.mysql.com/14637))

   * Added the `SHA2()' function, which calculates the SHA-2 family of
     hash functions (SHA-224, SHA-256, SHA-384, and SHA-512).
     (Contributed by Bill Karwin) (Bug#13174
     (http://bugs.mysql.com/13174))

   * The new read-only global system variables `report_host',
     `report_password', `report_port', and `report_user' system
     variables provide runtime access to the values of the corresponding
     `--report-host', `--report-password', `--report-port', and
     `--report-user' options.

   * Formerly it was possible to specify an `innodb_flush_method' value
     of `fdatasync' to obtain the default flush behavior of using
     `fdatasync()' for flushing.  This is no longer possible because it
     can be confusing that a value of `fdatasync' causes use of
     `fsync()' rather than `fdatasync()'.

   * The use of `InnoDB' hash indexes now can be controlled by setting
     the new `innodb_adaptive_hash_index' system variable at server
     startup. By default, this variable is enabled. See *Note
     innodb-adaptive-hash::.

   * The argument for the `mysql-test-run.pl' `--do-test' and
     `--skip-test' options is now interpreted as a Perl regular
     expression if there is a pattern metacharacter in the argument
     value. This allows more flexible specification of which tests to
     perform or skip.

   * The Instance Manager (`mysqlmanager') has been discontinued and is
     no longer provided in MySQL releases.

   * For `Falcon', supernodes have been added to index pages.
     Supernodes are an array of 16 vectors into each index page to keys
     that are fully expanded with noprefix compression. This allows the
     page to be searched quicker using a binary search of supernode
     keys followed by the normal sequential search. Without enabling
     supernodes, the whole page has to be searched sequentially.

   * Two new statements, *Note `BACKUP DATABASE': backup-database. and
     *Note `RESTORE': restore, have been added for backup and restore
     operations. See *Note backup-database-restore::.

Bugs fixed:

   * *Important Change*: *Security Fix*: It was possible to circumvent
     privileges through the creation of `MyISAM' tables employing the
     `DATA DIRECTORY' and `INDEX DIRECTORY' options to overwrite
     existing table files in the MySQL data directory. Use of the MySQL
     data directory in `DATA DIRECTORY' and `INDEX DIRECTORY' is now
     disallowed. This is now also true of these options when used with
     partitioned tables and individual partitions of such tables.

     *Note*:

     Additional fixes were made in MySQL 6.0.6.

     (Bug#32167 (http://bugs.mysql.com/32167), CVE-2008-2079
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-2079)) See
     also Bug#39277 (http://bugs.mysql.com/39277).

   * *Security Fix*: A client that connects to a malicious server could
     be tricked by the server into sending files from the client host
     to the server. This occurs because the `libmysqlclient' client
     library would respond to a `FETCH LOCAL FILE' request from the
     server even if the request is sent for statements from the client
     other than *Note `LOAD DATA LOCAL INFILE': load-data. The client
     library has been modified to respond to a `FETCH LOCAL FILE'
     request from the server only if is is sent in response to a *Note
     `LOAD DATA LOCAL INFILE': load-data. statement from the client.

     The client library now also checks whether `CLIENT_LOCAL_FILE' is
     set and refuses to send a local file if not.

     *Note*:

     Binary distributions ship with the `local-infile' capability
     enabled.  Applications that do not use this functionality should
     disable it to be safe.

     (Bug#29605 (http://bugs.mysql.com/29605))

   * *Important Change*: *Security Enhancement*: On Windows Vista and
     Windows Server 2008, a user without administrative privileges does
     not have write permissions to the `Program Files' directory where
     MySQL and the associated data files are normally installed. Using
     data files located in the standard `Program Files' installation
     directory could therefore cause MySQL to fail, or lead to
     potential security issues in an installed instance.

     To address the problem, on Windows XP, Windows Vista and Windows
     Server 2008, the datafiles and data file configuration are now set
     to the Microsoft recommended `AppData' folder. The `AppData'
     folder is typically located within the user's home directory.

     *Important*:

     When upgrading an existing 5.1.23 or 6.0.4 installation of MySQL
     you must take a backup of your data and configuration file
     (`my.ini' before installing the new version. To migrate your data,
     either extract the data and re-import (using *Note `mysqldump':
     mysqldump, then upgrade and re-import using *Note `mysql':
     mysql.), or back up your data, upgrade to the new version, and
     copy your existing data files from your old `datadir' directory to
     the new directory located within `AppData'.

     Failure to back up your data and follow these procedures may lead
     to data loss.

     (Bug#34593 (http://bugs.mysql.com/34593))

   * *Security Enhancement*: It was possible to force an error message
     of excessive length which could lead to a buffer overflow. This
     has been made no longer possible as a security precaution.
     (Bug#32707 (http://bugs.mysql.com/32707))

   * *Incompatible Change*: In MySQL 5.1.23, the `last_errno' and
     `last_error' members of the `NET' structure in `mysql_com.h' were
     renamed to `client_last_errno' and `client_last_error'. This was
     found to cause problems for connectors that use the internal `NET'
     structure for error handling. The change has been reverted.
     (Bug#34655 (http://bugs.mysql.com/34655)) See also Bug#12713
     (http://bugs.mysql.com/12713).

   * *Incompatible Change*: The parser accepted illegal syntax in a
     `FOREIGN KEY' clause:

        * Multiple `MATCH' clauses.

        * Multiple `ON DELETE' clauses.

        * Multiple `ON UPDATE' clauses.

        * `MATCH' clauses specified after `ON UPDATE' or `ON DELETE'.
          In case of multiple redundant clauses, this leads to
          confusion, and implementation-dependent results.

     These illegal syntaxes are now properly rejected. Existing
     applications that used them will require adjustment.  (Bug#34455
     (http://bugs.mysql.com/34455))

   * *Incompatible Change*: It was possible to use `FRAC_SECOND' as a
     synonym for `MICROSECOND' with `DATE_ADD()', `DATE_SUB()', and
     `INTERVAL'; now, using `FRAC_SECOND' with anything other than
     `TIMESTAMPADD()' or `TIMESTAMPDIFF()' produces a syntax error.

     It is now possible (and preferable) to use `MICROSECOND' with
     `TIMESTAMPADD()' and `TIMESTAMPDIFF()', and `FRAC_SECOND' is now
     deprecated.  (Bug#33834 (http://bugs.mysql.com/33834))

   * *Incompatible Change*: The *Note `UPDATE': update. statement
     allowed `NULL' to be assigned to `NOT NULL' columns (the implicit
     default value for the column data type was assigned). This was
     changed so that on error occurs.

     This change was reverted, because the original report was
     determined not to be a bug: Assigning `NULL' to a `NOT NULL'
     column in an *Note `UPDATE': update. statement should produce an
     error only in strict SQL mode and set the column to the implicit
     default with a warning otherwise, which was the original behavior.
     See *Note data-type-defaults::, and Bug#39265
     (http://bugs.mysql.com/39265).  (Bug#33699
     (http://bugs.mysql.com/33699))

   * *Incompatible Change*: It is no longer possible to create `CSV'
     tables with `NULL' columns. However, for backwards compatibility,
     you can continue to use such tables that were created in previous
     MySQL releases.  (Bug#32050 (http://bugs.mysql.com/32050))

   * *Incompatible Change*: For packages that are built within their
     own prefix (for example, `/usr/local/mysql') the plugin directory
     will be `lib/plugin'. For packages that are built to be installed
     into a system-wide prefix (such as RPM packages with a prefix of
     `/usr'), the plugin directory will be `lib/mysql/plugin' to ensure
     a clean `/usr/lib' hierarchy. In both cases, the `$pkglibdir'
     configuration setting is used at build time to set the plugin
     directory.

     The current plugin directory location is available as the value of
     the `plugin_dir' system variable as before, but the *Note
     `mysql_config': mysql-config.  script now has a `--plugindir'
     option that can be used externally to the server by third-party
     plugin writers to obtain the default plugin directory path name
     and configure their installation directory appropriately.
     (Bug#31736 (http://bugs.mysql.com/31736))

   * *Incompatible Change*: Inserting a row with a `NULL' value for a
     *Note `DATETIME': datetime. column results in a `CSV' file that
     the storage engine cannot read.

     All `CSV' tables now need to be defined with each column marked as
     `NOT NULL'. An error is raised if you try to create a `CSV' table
     with columns that are not defined with `NOT NULL'.  (Bug#31473
     (http://bugs.mysql.com/31473), Bug#32817
     (http://bugs.mysql.com/32817))

   * *Incompatible Change*: The `utf8_general_ci' and `ucs2_general_ci'
     collations did not sort the letter "U+00DF SHARP S" equal to `'s''.

     As a result of this fix, any indexes on columns that use these
     collations (but only columns that use SHARP S) must be rebuilt
     when upgrading to 6.0.5 or higher. To do this, use *Note `ALTER
     TABLE': alter-table. to drop and re-add the indexes, or use *Note
     `mysqldump': mysqldump. to dump the affected tables and *Note
     `mysql': mysql. to reload the dump file.  (Bug#27877
     (http://bugs.mysql.com/27877)) See also Bug#37046
     (http://bugs.mysql.com/37046).

   * *Incompatible Change*: Several changes were made to the processing
     of multiple-table *Note `DELETE': delete. statements:

        * Statements could not perform cross-database deletes unless
          the tables were referred to without using aliases. This
          limitation has been lifted and table aliases now are allowed.

        * Previously, alias declarations could be given for tables
          elsewhere than in the TABLE_REFERENCES part of the syntax.
          This could lead to ambiguous statements that have unexpected
          results such as deleting rows from the wrong table. Example:

               DELETE FROM t1 AS a2 USING t1 AS a1 INNER JOIN t2 AS a2;

          Now alias declarations can be declared only in the
          TABLE_REFERENCES part. Elsewhere in the statement, alias
          references are allowed but not alias declarations.

        * Alias resolution was improved so that it is no longer
          possible to have inconsistent or ambiguous aliases for tables.

     Statements containing alias constructs that are no longer allowed
     must be rewritten.  (Bug#27525 (http://bugs.mysql.com/27525)) See
     also Bug#30234 (http://bugs.mysql.com/30234).

   * *Important Change*: *Replication*: When the master crashed during
     an update on a transactional table while in `autocommit' mode, the
     slave failed. This fix causes every transaction (including
     `autocommit' transactions) to be recorded in the binlog as
     starting with a *Note `BEGIN': commit. and ending with a *Note
     `COMMIT': commit. or *Note `ROLLBACK': commit.  (Bug#26395
     (http://bugs.mysql.com/26395))

   * *Important Change*: `InnoDB' free space information is now shown in
     the `Data_free' column of *Note `SHOW TABLE STATUS':
     show-table-status. and in the `DATA_FREE' column of the *Note
     `INFORMATION_SCHEMA.TABLES': tables-table. table.  (Bug#32440
     (http://bugs.mysql.com/32440)) See also Bug#11379
     (http://bugs.mysql.com/11379).

   * *Important Change*: The server handled truncation of values having
     excess trailing spaces into *Note `CHAR': char, *Note `VARCHAR':
     char, and *Note `TEXT': blob. columns in different ways.  This
     behavior has now been made consistent for columns of all three of
     these types, and now follows the existing behavior of *Note
     `VARCHAR': char. columns in this regard; that is, a `Note' is
     always issued whenever such truncation occurs.

     This change does not affect columns of these three types when
     using a binary encoding; *Note `BLOB': blob.  columns are also
     unaffected by the change, since they always use a binary encoding.
     (Bug#30059 (http://bugs.mysql.com/30059))

   * *Important Change*: An `AFTER UPDATE' trigger was not invoked when
     the *Note `UPDATE': update. did not make any changes to the table
     for which the trigger was defined. Now `AFTER UPDATE' triggers
     behave the same in this regard as do `BEFORE UPDATE' triggers,
     which are invoked whether the *Note `UPDATE': update.  makes any
     changes in the table or not.  (Bug#23771
     (http://bugs.mysql.com/23771))

   * *Partitioning*: *Important Note*: The following statements did not
     function correctly with corrupted or crashed tables and have been
     disabled:

        * `ALTER TABLE ... ANALYZE PARTITION'

        * `ALTER TABLE ... CHECK PARTITION'

        * `ALTER TABLE ... OPTIMIZE PARTITION'

        * `ALTER TABLE ... REPAIR PARTITION'

     `ALTER TABLE ... REBUILD PARTITION' is unaffected by this change
     and continues to be available. This statement and `ALTER TABLE ...
     REORGANIZE PARTITION' may be used to analyze and optimize
     partitioned tables, since these operations cause the partition
     files to be rebuilt.  (Bug#20129 (http://bugs.mysql.com/20129))
     See also Bug#39434 (http://bugs.mysql.com/39434).

   * *Replication*: *Important Note*: Network timeouts between the
     master and the slave could result in corruption of the relay log.
     This fix rectifies a long-standing replication issue when using
     unreliable networks, including replication over wide area networks
     such as the Internet. If you experience reliability issues and see
     many `You have an error in your SQL syntax' errors on replication
     slaves, we strongly recommend that you upgrade to a MySQL version
     which includes this fix.  (Bug#26489 (http://bugs.mysql.com/26489))

   * *MySQL Cluster*: When all data and SQL nodes in the cluster were
     shut down abnormally (that is, other than by using `STOP' in the
     cluster management client), `ndb_mgm' used excessive amounts of
     CPU.  (Bug#33237 (http://bugs.mysql.com/33237))

   * *MySQL Cluster*: There was a short interval during the startup
     process prior to the beginning of heartbeat detection such that,
     were an API or management node to reboot or a network failure to
     occur, data nodes could not detect this, with the result that
     there could be a lingering connection.  (Bug#28445
     (http://bugs.mysql.com/28445))

   * *Partitioning*: In some cases, matching rows from a partitioned
     `MyISAM' using a *Note `BIT': numeric-types. column as the primary
     key were not found by queries.  (Bug#34358
     (http://bugs.mysql.com/34358))

   * *Partitioning*: Enabling `innodb_file_per_table' produced problems
     with partitioning and tablespace operations on partitioned
     `InnoDB' tables, in some cases leading to corrupt partitions or
     causing the server to crash.  (Bug#33429
     (http://bugs.mysql.com/33429))

   * *Partitioning*: A table defined using `PARTITION BY KEY' and
     having a *Note `BIT': numeric-types. column referenced in the
     partitioning key did not behave correctly; some rows could be
     inserted into the wrong partition, causing wrong results to be
     returned from queries.  (Bug#33379 (http://bugs.mysql.com/33379))

   * *Partitioning*: It was possible to partition a table to which a
     foreign key referred.  (Bug#32948 (http://bugs.mysql.com/32948))

   * *Partitioning*: When `ALTER TABLE DROP PARTITION' was executed on
     a table on which there was a trigger, the statement failed with an
     error. This occurred even if the trigger did not reference any
     tables.  (Bug#32943 (http://bugs.mysql.com/32943))

   * *Partitioning*: A query of the form `SELECT COL1 FROM TABLE GROUP
     BY (SELECT COL2 FROM TABLE LIMIT 1);' against a partitioned TABLE
     having a `SET' column crashed the server.  (Bug#32772
     (http://bugs.mysql.com/32772))

   * *Partitioning*: *Note `SHOW CREATE TABLE': show-create-table.
     misreported the value of `AUTO_INCREMENT' for partitioned tables
     using either of the `InnoDB' or `ARCHIVE' storage engines.
     (Bug#32247 (http://bugs.mysql.com/32247))

   * *Partitioning*: Selecting from *Note
     `INFORMATION_SCHEMA.PARTITIONS': partitions-table. while partition
     management statements (for example, `ALTER TABLE ... ADD
     PARTITION') were executing caused the server to crash.  (Bug#32178
     (http://bugs.mysql.com/32178))

   * *Partitioning*: An error in the internal function
     `mysql_unpack_partition()' led to a fatal error in subsequent
     calls to `open_table_from_share()'.  (Bug#32158
     (http://bugs.mysql.com/32158))

   * *Partitioning*: Currently, all partitions of a partitioned table
     must use the same storage engine. One may optinally specify the
     storage engine on a per-partition basis; however, where this is the
     done, the storage engine must be the same as used by the table as
     a whole. *Note `ALTER TABLE': alter-table. did not enforce these
     rules correctly, the result being that incaccurate error messages
     were shown when trying to use the statement to change the storage
     engine used by an individual partition or partitions.  (Bug#31931
     (http://bugs.mysql.com/31931))

   * *Partitioning*: `ORDER BY ... DESC' did not always work correctly
     when selecting from partitioned tables.  (Bug#31890
     (http://bugs.mysql.com/31890)) See also Bug#31001
     (http://bugs.mysql.com/31001).

   * *Partitioning*: `ALTER TABLE ... COALESCE PARTITION' on a table
     partitioned by `[LINEAR] HASH' or `[LINEAR] KEY' caused the server
     to crash.  (Bug#30822 (http://bugs.mysql.com/30822))

   * *Partitioning*: When the `range' access method was used on a
     partitioned `Falcon' table, the entire index was scanned. For
     partitioned tables using other storage engines, a related issue
     caused an ordered range scan to return some rows twice.
     (Bug#30573 (http://bugs.mysql.com/30573), Bug#33257
     (http://bugs.mysql.com/33257), Bug#33555
     (http://bugs.mysql.com/33555))

   * *Partitioning*: `LIKE' queries on tables partitioned by `KEY'
     could return incomplete results. The problem was observed with the
     `Falcon' storage engine, but could affect third-party storage
     engines as well.  (Bug#30480 (http://bugs.mysql.com/30480)) See
     also Bug#29320 (http://bugs.mysql.com/29320), Bug#29493
     (http://bugs.mysql.com/29493), Bug#30563
     (http://bugs.mysql.com/30563).

   * *Partitioning*: Using the DATA DIRECTORY and INDEX DIRECTORY
     options for partitions with CREATE TABLE or ALTER TABLE statements
     appeared to work on Windows, although they are not supported by
     MySQL on Windows systems, and subsequent attempts to use the tables
     referenced caused errors. Now these options are disabled on
     Windows, and attempting to use them generates a warning.
     (Bug#30459 (http://bugs.mysql.com/30459))

   * *Partitioning*: It was not possible to insert the greatest
     possible value for a given data type into a partitioned table. For
     example, consider a table defined as shown here:

          CREATE TABLE t (c BIGINT UNSIGNED)
              PARTITION BY RANGE(c) (
                PARTITION p0 VALUES LESS THAN MAXVALUE
              );

     The largest possible value for a `BIGINT UNSIGNED' column is
     18446744073709551615, but the statement `INSERT INTO t VALUES
     (18446744073709551615);' would fail, even though the same
     statement succeeded were `t' not a partitioned table.

     In other words, `MAXVALUE' was treated as being equal to the
     greatest possible value, rather than as a least upper bound.
     (Bug#29258 (http://bugs.mysql.com/29258))

   * *Replication*: Replicating a Falcon table that contained a *Note
     `TEXT': blob. or *Note `BLOB': blob. column would fail during a
     *Note `DELETE': delete. operation with the error
     `HA_ERR_END_OF_FILE'.  (Bug#36468 (http://bugs.mysql.com/36468))

   * *Replication*: When using row-based replication, a slave could
     crash at startup because it received a row-based replication event
     that `InnoDB' could not handle due to an incorrect test of the
     query string provided by MySQL, which was `NULL' for row-based
     replication events.  (Bug#35226 (http://bugs.mysql.com/35226))

   * *Replication*: `insert_id' was not written to the binary log for
     inserts into `BLACKHOLE' tables.  (Bug#35178
     (http://bugs.mysql.com/35178))

   * *Replication*: When using statement-based replication and a *Note
     `DELETE': delete, *Note `UPDATE': update, or *Note `INSERT ...
     SELECT': insert-select. statement using a `LIMIT' clause is
     encountered, a warning that the statement is not safe to replicate
     in statement mode is now issued; when using `MIXED' mode, the
     statement is now replicated using the row-based format.
     (Bug#34768 (http://bugs.mysql.com/34768))

   * *Replication*: *Note `mysqlbinlog': mysqlbinlog. did not output
     the values of `auto_increment_increment' and
     `auto_increment_offset' when both were equal to their default
     values (for both of these variables, the default is 1). This meant
     that a binary log recorded by a client using the defaults for both
     variables and then replayed on another client using its own values
     for either or both of these variables produced erroneous results.
     (Bug#34732 (http://bugs.mysql.com/34732)) See also Bug#31168
     (http://bugs.mysql.com/31168).

   * *Replication*: A *Note `CHANGE MASTER TO': change-master-to.
     statement with no `MASTER_HEARTBEAT_PERIOD' option failed to reset
     the heartbeat period to its default value.  (Bug#34686
     (http://bugs.mysql.com/34686))

   * *Replication*: *Note `SHOW SLAVE STATUS': show-slave-status.
     failed when slave I/O was about to terminate.  (Bug#34305
     (http://bugs.mysql.com/34305))

   * *Replication*: The character sets and collations used for constant
     identifiers in stored procedures were not replicated correctly.
     (Bug#34289 (http://bugs.mysql.com/34289))

   * *Replication*: *Note `mysqlbinlog': mysqlbinlog. from a 5.1 or
     later MySQL distribution could not read binary logs generated by a
     4.1 server when the logs contained *Note `LOAD DATA INFILE':
     load-data. statements.  (Bug#34141 (http://bugs.mysql.com/34141))
     This regression was introduced by Bug#32407
     (http://bugs.mysql.com/32407).

   * *Replication*: A *Note `CREATE USER': create-user, *Note `DROP
     USER': drop-user, or *Note `RENAME USER': rename-user. statement
     that fails on the master, or that is a duplicate of any of these
     statements, is no longer written to the binlog; previously, either
     of these occurrences could cause the slave to fail.

     (Bug#33862 (http://bugs.mysql.com/33862)) See also Bug#29749
     (http://bugs.mysql.com/29749).

   * *Replication*: *Note `SHOW BINLOG EVENTS': show-binlog-events.
     could fail when the binlog contained one or more events whose size
     was close to the value of `max_allowed_packet'.  (Bug#33413
     (http://bugs.mysql.com/33413))

   * *Replication*: *Note `mysqlbinlog': mysqlbinlog. failed to release
     all of its memory after terminating abnormally.  (Bug#33247
     (http://bugs.mysql.com/33247))

   * *Replication*: When a stored routine or trigger, running on a
     master that used MySQL 5.0 or MySQL 5.1.11 or earlier, performed
     an insert on an `AUTO_INCREMENT' column, the `insert_id' value was
     not replicated correctly to a slave running MySQL 5.1.12 or later
     (including any MySQL 6.0 release).  (Bug#33029
     (http://bugs.mysql.com/33029)) See also Bug#19630
     (http://bugs.mysql.com/19630).

   * *Replication*: The error message generated due to lack of a
     default value for an extra column was not sufficiently informative.
     (Bug#32971 (http://bugs.mysql.com/32971))

   * *Replication*: When a user variable was used inside an *Note
     `INSERT': insert. statement, the corresponding binlog event was
     not written to the binlog correctly.  (Bug#32580
     (http://bugs.mysql.com/32580))

   * *Replication*: When using row-based replication, deletes from a
     table with a foreign key constraint failed on the slave.
     (Bug#32468 (http://bugs.mysql.com/32468))

   * *Replication*: The `--base64-output' option for *Note
     `mysqlbinlog': mysqlbinlog. was not honored for all types of
     events. This interfered in some cases with performing
     point-in-time recovery.  (Bug#32407 (http://bugs.mysql.com/32407))

   * *Replication*: SQL statements containing comments using `--'
     syntax were not replayable by *Note `mysqlbinlog': mysqlbinlog,
     even though such statements replicated correctly.  (Bug#32205
     (http://bugs.mysql.com/32205))

   * *Replication*: When using row-based replication from a master
     running MySQL 6.0.3 or earlier to a slave running 6.0.4 or later,
     updates of integer columns failed on the slave with `Error in
     Unknown event: row application failed'.  (Bug#31583
     (http://bugs.mysql.com/31583)) This regression was introduced by
     Bug#21842 (http://bugs.mysql.com/21842).

   * *Replication*: Replicating write, update, or delete events from a
     master running MySQL 5.1.15 or earlier to a slave running 5.1.16 or
     later caused the slave to crash.  (Bug#31581
     (http://bugs.mysql.com/31581))

   * *Replication*: When using row-based replication, the slave stopped
     when attempting to delete non-existent rows from a slave table
     without a primary key. In addition, no error was reported when
     this occurred.  (Bug#31552 (http://bugs.mysql.com/31552))

   * *Replication*: Errors due to server ID conflicts were reported
     only in the slave's error log; now these errors are also shown in
     the `Server_IO_State' column in the output of *Note `SHOW SLAVE
     STATUS': show-slave-status.  (Bug#31316
     (http://bugs.mysql.com/31316))

   * *Replication*: *Note `STOP SLAVE': stop-slave. did not stop
     connection attempts properly. If the IO slave thread was
     attempting to connect, *Note `STOP SLAVE': stop-slave.  waited for
     the attempt to finish, sometimes for a long period of time, rather
     than stopping the slave immediately.  (Bug#31024
     (http://bugs.mysql.com/31024)) See also Bug#30932
     (http://bugs.mysql.com/30932).

   * *Replication*: Issuing a *Note `DROP VIEW': drop-view. statement
     caused replication to fail if the view did not actually exist.
     (Bug#30998 (http://bugs.mysql.com/30998))

   * *Replication*: Replication of *Note `LOAD DATA INFILE': load-data.
     could fail when `read_buffer_size' was larger than
     `max_allowed_packet'.  (Bug#30435 (http://bugs.mysql.com/30435))

   * *Replication*: Replication crashed with the `NDB' storage engine
     when *Note `mysqld': mysqld. was started with
     `--character-set-server=ucs2'.  (Bug#29562
     (http://bugs.mysql.com/29562))

   * *Replication*: The effects of scheduled events were not always
     correctly reproduced on the slave when using row-based replication.
     (Bug#29020 (http://bugs.mysql.com/29020))

   * *Replication*: Setting `server_id' did not update its value for
     the current session.  (Bug#28908 (http://bugs.mysql.com/28908))

   * *Replication*: Some older servers wrote events to the binary log
     using different numbering from what is currently used, even though
     the file format number in the file is the same. Slaves running
     MySQL 5.1.18 and later could not read these binary logs properly.
     Binary logs from these older versions now are recognized and event
     numbers are mapped to the current numbering so that they can be
     interpreted properly.  (Bug#27779 (http://bugs.mysql.com/27779),
     Bug#32434 (http://bugs.mysql.com/32434)) This regression was
     introduced by Bug#22583 (http://bugs.mysql.com/22583).

   * *Replication*: `MASTER_POS_WAIT()' did not return `NULL' when the
     server was not a slave.  (Bug#26622 (http://bugs.mysql.com/26622))

   * *Replication*: The inspecific error message `Wrong parameters to
     function register_slave' resulted when *Note `START SLAVE':
     start-slave. failed to register on the master due to excess length
     of any the slave server options `--report-host', `--report-user',
     or `--report-password'. An error message specific to each of these
     options is now returned in such cases. The new error messages are:

        * `Failed to register slave: too long 'report-host''

        * `Failed to register slave: too long 'report-user''

        * `Failed to register slave; too long 'report-password''

     (Bug#22989 (http://bugs.mysql.com/22989)) See also Bug#19328
     (http://bugs.mysql.com/19328).

   * *Replication*: `PURGE BINARY LOGS TO' and `PURGE BINARY LOGS
     BEFORE' did not handle missing binary log files correctly or in
     the same way. Now for both of these statements, if any files
     listed in the `.index' file are missing from the file system, the
     statement fails with an error.

   * *API*: When the language option was not set correctly, API programs
     calling *Note `mysql_server_init()': mysql-server-init.  crashed.
     This issue was observed only on Windows platforms.  (Bug#31868
     (http://bugs.mysql.com/31868))

   * Corrected a typecast involving `bool' on Mac OS X 10.5 (Leopard),
     which evaluated differently from earlier Mac OS X versions.
     (Bug#38217 (http://bugs.mysql.com/38217))

   * Queries could return different results depending on whether the
     join buffer was or was not used.  (Bug#37131
     (http://bugs.mysql.com/37131))

   * *Note `BACKUP DATABASE': backup-database. did not correctly
     determine dependency ordering of backed-up objects, which could
     cause a *Note `RESTORE': restore. operation to fail.  (Bug#36531
     (http://bugs.mysql.com/36531))

   * Concurrent *Note `LOAD DATA INFILE': load-data. statements
     inserting data into `Falcon' tables could crash the server.
     (Bug#35982 (http://bugs.mysql.com/35982))

   * Following a server crash, recovery of `Falcon' tables containing
     *Note `BLOB': blob. or *Note `TEXT': blob. columns could lose data.
     (Bug#35688 (http://bugs.mysql.com/35688))

   * Manually replacing a binary log file with a directory having the
     same name caused an error that was not handled correctly.
     (Bug#35675 (http://bugs.mysql.com/35675))

   * Using *Note `LOAD DATA INFILE': load-data. with a view could crash
     the server.  (Bug#35469 (http://bugs.mysql.com/35469))

   * Selecting from *Note `INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS':
     referential-constraints-table.  could cause a server crash.
     (Bug#35406 (http://bugs.mysql.com/35406)) See also Bug#35108
     (http://bugs.mysql.com/35108).

   * For a `TEMPORARY' table, *Note `DELETE': delete. with no `WHERE'
     clause could fail when preceded by *Note `DELETE': delete.
     statements with a `WHERE' clause.  (Bug#35392
     (http://bugs.mysql.com/35392))

   * In some cases, when too many clients tried to connect to the
     server, the proper `SQLSTATE' code was not returned.  (Bug#35289
     (http://bugs.mysql.com/35289))

   * Memory-allocation failures for attempts to set `key_buffer_size'
     to large values could result in a server crash.  (Bug#35272
     (http://bugs.mysql.com/35272))

   * Queries could return different results depending on whether `ORDER
     BY' columns were indexed.  (Bug#35206
     (http://bugs.mysql.com/35206))

   * When a view containing a reference to `DUAL' was created, the
     reference was removed when the definition was stored, causing some
     queries against the view to fail with invalid SQL syntax errors.
     (Bug#35193 (http://bugs.mysql.com/35193))

   * `SELECT ... FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS'
     caused the server to crash if the table referenced by a foreign
     key had been dropped. This issue was observed on Windows platforms
     only.  (Bug#35108 (http://bugs.mysql.com/35108)) See also
     Bug#35406 (http://bugs.mysql.com/35406).

   * Debugging symbols were missing for some executables in Windows
     binary distributions.  (Bug#35104 (http://bugs.mysql.com/35104))

   * Non-connection threads were being counted in the value of the
     `Max_used_connections' status variable.  (Bug#35074
     (http://bugs.mysql.com/35074))

   * Two different threads could obtain the same record number for
     concurrent inserts into the same `Falcon' table.  (Bug#34990
     (http://bugs.mysql.com/34990))

   * A query that performed a `ref_or_null' join where the second table
     used a key having one or columns that could be `NULL' and had a
     column value that was `NULL' caused the server to crash.
     (Bug#34945 (http://bugs.mysql.com/34945)) This regression was
     introduced by Bug#12144 (http://bugs.mysql.com/12144).

   * For some queries, the optimizer used an ordered index scan for
     `GROUP BY' or `DISTINCT' when it was supposed to use a loose index
     scan, leading to incorrect results.  (Bug#34928
     (http://bugs.mysql.com/34928))

   * Creating a foreign key on an `InnoDB' table that was created with
     an explicit `AUTO_INCREMENT' value caused that value to be reset
     to 1.  (Bug#34920 (http://bugs.mysql.com/34920))

   * *Note `mysqldump': mysqldump. failed to return an error code when
     using the `--master-data' option without binary logging being
     enabled on the server.  (Bug#34909 (http://bugs.mysql.com/34909))

   * Under some circumstances, the value of *Note `mysql_insert_id()':
     mysql-insert-id. following a `SELECT ... INSERT' statement could
     return an incorrect value. This could happen when the last `SELECT
     ... INSERT' did not involve an `AUTO_INCREMENT' column, but the
     value of *Note `mysql_insert_id()': mysql-insert-id. was changed by
     some previous statements.  (Bug#34889
     (http://bugs.mysql.com/34889))

   * Logging to the progress tables used by *Note `BACKUP DATABASE':
     backup-database. and *Note `RESTORE': restore. caused a server
     crash.  (Bug#34858 (http://bugs.mysql.com/34858))

   * Table and database names were mixed up in some places of the
     subquery transformation procedure. This could affect debugging
     trace output and further extensions of that procedure.  (Bug#34830
     (http://bugs.mysql.com/34830))

   * If `fsync()' returned `ENOLCK', `InnoDB' could treat this as fatal
     and cause abnormal server termination.  `InnoDB' now retries the
     operation.  (Bug#34823 (http://bugs.mysql.com/34823))

   * *Note `CREATE SERVER': create-server. and *Note `ALTER SERVER':
     alter-server. could crash the server if out-of-memory conditions
     occurred.  (Bug#34790 (http://bugs.mysql.com/34790))

   * *Note `DROP SERVER': drop-server. does not release memory cached
     for server structures created by *Note `CREATE SERVER':
     create-server, so repeated iterations of these statements resulted
     in a memory leak.  *Note `FLUSH PRIVILEGES': flush. now releases
     the memory allocated for *Note `CREATE SERVER': create-server.
     (Bug#34789 (http://bugs.mysql.com/34789))

   * A malformed URL used for a `FEDERATED' table's `CONNECTION' option
     value in a *Note `CREATE TABLE': create-table. statement was not
     handled correctly and could crash the server.  (Bug#34788
     (http://bugs.mysql.com/34788))

   * Repeated *Note `UPDATE': update. operations on a `Falcon' table
     could cause a memory leak.  (Bug#34778
     (http://bugs.mysql.com/34778))

   * Queries such as `SELECT ROW(1, 2) IN (SELECT t1.a, 2) FROM t1
     GROUP BY t1.a' (combining row constructors and subqueries in the
     `FROM' clause) could lead to assertion failure or unexpected error
     messages.  (Bug#34763 (http://bugs.mysql.com/34763))

   * Using `NAME_CONST()' with a negative number and an aggregate
     function caused MySQL to crash. This could also have a negative
     impact on replication.  (Bug#34749 (http://bugs.mysql.com/34749))

   * A memory-handling error associated with use of `GROUP_CONCAT()' in
     subqueries could result in a server crash.  (Bug#34747
     (http://bugs.mysql.com/34747))

   * For an indexed integer column COL_NAME and a value N that is one
     greater than the maximum value allowed for the data type of
     COL_NAME, conditions of the form `WHERE COL_NAME < N' failed to
     return rows where the value of COL_NAME is `N - 1'.  (Bug#34731
     (http://bugs.mysql.com/34731))

   * A server running with the `--debug' option could attempt to
     dereference a null pointer when opening tables, resulting in a
     crash.  (Bug#34726 (http://bugs.mysql.com/34726))

   * Assigning an `incremental' value to the `debug' system variable
     did not add the new value to the current value. For example, if the
     current `debug' value was `'T'', the statement `SET debug = '+P''
     resulted in a value of `'P'' rather than the correct value of
     `'P:T''.  (Bug#34678 (http://bugs.mysql.com/34678))

   * For debug builds, reading from *Note `INFORMATION_SCHEMA.TABLES':
     tables-table. or *Note `INFORMATION_SCHEMA.COLUMNS':
     columns-table. could cause assertion failures. This could happen
     under rare circumstances when `INFORMATION_SCHEMA' fails to get
     information about a table (for example, when a connection is
     killed).  (Bug#34656 (http://bugs.mysql.com/34656))

   * Executing a *Note `TRUNCATE': truncate. statement on a table
     having both a foreign key reference and a *Note `DELETE': delete.
     trigger crashed the server.  (Bug#34643
     (http://bugs.mysql.com/34643))

   * Some subqueries using an expression that included an aggregate
     function could fail or in some cases lead to a crash of the server.
     (Bug#34620 (http://bugs.mysql.com/34620))

   * Dangerous pointer arithmetic crashed the server on some systems.
     (Bug#34598 (http://bugs.mysql.com/34598))

   * Creating a view inside a stored procedure could lead to a crash of
     the MySQL Server.  (Bug#34587 (http://bugs.mysql.com/34587))

   * Concurrent *Note `ALTER TABLE': alter-table. operations on
     temporary and non-temporary `Falcon' tables caused the server to
     hang.  (Bug#34567 (http://bugs.mysql.com/34567)) This regression
     was introduced by Bug#33634 (http://bugs.mysql.com/33634).

   * A server crash could occur if `INFORMATION_SCHEMA' tables built in
     memory were swapped out to disk during query execution.
     (Bug#34529 (http://bugs.mysql.com/34529))

   * `CAST(AVG(ARG) AS DECIMAL)' produced incorrect results for
     non-*Note `DECIMAL': numeric-types. arguments.  (Bug#34512
     (http://bugs.mysql.com/34512))

   * `SET GLOBAL falcon_record_chill_threshold' and `SET GLOBAL
     falcon_index_chill_threshold' did not work.  (Bug#34486
     (http://bugs.mysql.com/34486))

   * The per-thread debugging settings stack was not being deallocated
     before thread termination, resulting in a stack memory leak.
     (Bug#34424 (http://bugs.mysql.com/34424))

   * Client applications could not connect to the server on Windows
     Vista because the server was creating an IPv6-only TCP/IP socket.
     (Bug#34381 (http://bugs.mysql.com/34381))

   * Inserting a unique record into a `Falcon' table, then performing a
     *Note `DELETE': delete.  on the same record resulted in the error
     `Record has changed since last read'.  (Bug#34351
     (http://bugs.mysql.com/34351)) See also Bug#29151
     (http://bugs.mysql.com/29151), Bug#35321
     (http://bugs.mysql.com/35321).

   * Executing an *Note `ALTER VIEW': alter-view. statement on a table
     crashed the server.  (Bug#34337 (http://bugs.mysql.com/34337))

   * For `InnoDB', exporting and importing a table could corrupt *Note
     `TINYBLOB': blob. columns, and a subsequent *Note `ALTER TABLE':
     alter-table.  could corrupt *Note `TINYTEXT': blob. columns as
     well.  (Bug#34300 (http://bugs.mysql.com/34300))

   * On Windows, client programs generated assertion failures.
     (Bug#34298 (http://bugs.mysql.com/34298))

   * `DEFAULT 0' was not allowed for the *Note `YEAR': year. data type.
     (Bug#34274 (http://bugs.mysql.com/34274))

   * Under some conditions, a `SET GLOBAL innodb_commit_concurrency' or
     `SET GLOBAL innodb_autoextend_increment' statement could fail.
     (Bug#34223 (http://bugs.mysql.com/34223))

   * *Note `mysqldump': mysqldump. attempts to set the
     `character_set_results' system variable after connecting to the
     server. This failed for pre-4.1 servers that have no such
     variable, but *Note `mysqldump': mysqldump. did not account for
     this and 1) failed to dump database contents; 2) failed to produce
     any error message alerting the user to the problem.  (Bug#34192
     (http://bugs.mysql.com/34192))

   * Use of stored functions in the `WHERE' clause for *Note `SHOW OPEN
     TABLES': show-open-tables. caused a server crash.  (Bug#34166
     (http://bugs.mysql.com/34166))

   * Compilation failed on Solaris for the `ARCHIVE' storage engine due
     to inclusion of `getopt.h' in the `ARCHIVE' code.  (Bug#34094
     (http://bugs.mysql.com/34094))

   * `CREATE TABLE ... ENGINE=Falcon' failed with an unhelpful error
     message when the `Falcon' storage engine had failed to allocate
     the page cache properly on server startup. Now, `Falcon' is
     initialized on server startup, and is not loaded if the allocation
     fails.  (Bug#34085 (http://bugs.mysql.com/34085))

   * Updates of floating-point columns in `FEDERATED' tables could
     produce incorrect results.  (Bug#34015
     (http://bugs.mysql.com/34015))

   * For a `FEDERATED' table with an index on a nullable column,
     accessing the table could crash a server, return an incorrect
     result set, or return `ERROR 1030 (HY000): Got error 1430 from
     storage engine'.  (Bug#33946 (http://bugs.mysql.com/33946))

   * Passing anything other than a integer to a `LIMIT' clause in a
     prepared statement would fail. (This limitation was introduced to
     avoid replication problems; for example, replicating the statement
     with a string argument would cause a parse failure in the slave).
     Now, arguments to the `LIMIT' clause are converted to integer
     values, and these converted values are used when logging the
     statement.  (Bug#33851 (http://bugs.mysql.com/33851))

   * An internal buffer in *Note `mysql': mysql. was too short.
     Overextending it could cause stack problems or segmentation
     violations on some architectures. (This is not a problem that
     could be exploited to run arbitrary code.)  (Bug#33841
     (http://bugs.mysql.com/33841))

   * A query using `WHERE (column1='STRING1' AND column2=CONSTANT1) OR
     (column1='STRING2' AND column2=CONSTANT2)', where `col1' used a
     binary collation and STRING1 matched STRING2 except for case,
     failed to match any records even when matches were found by a
     query using the equivalent clause `WHERE column2=CONSTANT1 OR
     column2=CONSTANT2'.  (Bug#33833 (http://bugs.mysql.com/33833))

   * Large unsigned integers were improperly handled for prepared
     statements, resulting in truncation or conversion to negative
     numbers.  (Bug#33798 (http://bugs.mysql.com/33798))

   * Reuse of prepared statements could cause a memory leak in the
     embedded server.  (Bug#33796 (http://bugs.mysql.com/33796))

   * The server crashed when executing a query that had a subquery
     containing an equality X=Y where Y referred to a named select list
     expression from the parent select. The server crashed when trying
     to use the X=Y equality for `ref'-based access.  (Bug#33794
     (http://bugs.mysql.com/33794))

   * Some queries using a combination of `IN', `CONCAT()', and an
     implicit type conversion could return an incorrect result.
     (Bug#33764 (http://bugs.mysql.com/33764))

   * In some cases a query that produced a result set when using `ORDER
     BY ASC' did not return any results when this was changed to `ORDER
     BY DESC'.  (Bug#33758 (http://bugs.mysql.com/33758))

   * Disabling concurrent inserts caused some cacheable queries not to
     be saved in the query cache.  (Bug#33756
     (http://bugs.mysql.com/33756))

   * `ORDER BY ... DESC' sorts could produce misordered results.
     (Bug#33697 (http://bugs.mysql.com/33697))

   * Use of uninitialized memory for `filesort' in a subquery caused a
     server crash.  (Bug#33675 (http://bugs.mysql.com/33675))

   * The `WEIGHT_STRING()' function returned incorrect results for
     column values when earlier column values were `NULL'.  (Bug#33663
     (http://bugs.mysql.com/33663))

   * The server could crash when *Note `REPEAT': repeat-statement.  or
     another control instruction was used in conjunction with labels
     and a *Note `LEAVE': leave-statement.  instruction.  (Bug#33618
     (http://bugs.mysql.com/33618))

   * The parser allowed control structures in compound statements to
     have mismatched beginning and ending labels.  (Bug#33618
     (http://bugs.mysql.com/33618))

   * `make_binary_distribution' passed the `--print-libgcc-file' option
     to the C compiler, but this does not work with the `ICC' compiler.
     (Bug#33536 (http://bugs.mysql.com/33536))

   * Threads created by the event scheduler were incorrectly counted
     against the `max_connections' thread limit, which could lead to
     client lockout.  (Bug#33507 (http://bugs.mysql.com/33507))

   * `CREATE TABLE ... ENGINE=Falcon' failed on kernel 2.4 based Linux
     systems when using `O_DIRECT' with an NFS file system.  (Bug#33484
     (http://bugs.mysql.com/33484))

   * Dropping a function after dropping the function's creator could
     cause the server to crash.  (Bug#33464
     (http://bugs.mysql.com/33464))

   * For the `latin2_czech_cs' collation, the primary weights for all
     variants of capital letters `U' and `O' were incorrect (were not
     equal to the corresponding small letters).

     As a result of this bug fix, indexes must be rebuilt for columns
     that use the `latin2_czech_cs collation'. See *Note
     checking-index-changes::.  (Bug#33452
     (http://bugs.mysql.com/33452))

   * Certain combinations of views, subselects with outer references
     and stored routines or triggers could cause the server to crash.
     (Bug#33389 (http://bugs.mysql.com/33389))

   * `SET GLOBAL myisam_max_sort_file_size=DEFAULT' set
     `myisam_max_sort_file_size' to an incorrect value.  (Bug#33382
     (http://bugs.mysql.com/33382)) See also Bug#31177
     (http://bugs.mysql.com/31177).

   * *Note `ENUM': enum.- or `SET'-valued plugin variables could not be
     set from the command line.  (Bug#33358
     (http://bugs.mysql.com/33358))

   * If the `mysql' database was named in the *Note `BACKUP DATABASE':
     backup-database. statement, the backup operation hung.  (Bug#33355
     (http://bugs.mysql.com/33355))

   * Loading plugins via command-line options to *Note `mysqld':
     mysqld. could cause an assertion failure.  (Bug#33345
     (http://bugs.mysql.com/33345))

   * `SLEEP(0)' failed to return on 64-bit Mac OS X due to a bug in
     `pthread_cond_timedwait()'.  (Bug#33304
     (http://bugs.mysql.com/33304))

   * `CREATE TABLE ... SELECT' created tables that for date columns
     used the obsolete `Field_date' type instead of `Field_newdate'.
     (Bug#33256 (http://bugs.mysql.com/33256))

   * For `MyISAM' tables, *Note `CHECK TABLE': check-table.
     (non-`QUICK') and any form of *Note `REPAIR TABLE': repair-table.
     incorrected treated rows as corrupted under the combination of the
     following conditions:

        * The table had dynamic row format

        * The table had a *Note `CHAR': char. (not *Note `VARCHAR':
          char.) column longer than 127 bytes (for multi-byte character
          sets this could be less than 127 characters)

        * The table had rows with a signifcant length of more than 127
          bytes significant length in that *Note `CHAR': char. column
          (that is, a byte beyond byte position 127 must be a non-space
          character)

     This problem affected *Note `CHECK TABLE': check-table, *Note
     `REPAIR TABLE': repair-table, *Note `OPTIMIZE TABLE':
     optimize-table, *Note `ALTER TABLE': alter-table.  *Note `CHECK
     TABLE': check-table. reported and marked the table as crashed if
     any row was present that fulfilled the third condition. The other
     statements deleted these rows.  (Bug#33222
     (http://bugs.mysql.com/33222))

   * The error message was vague for attempts to drop a `Falcon'
     tablespace that contained tables. Now the message `Tablespace
     busy' is returned.  (Bug#33216 (http://bugs.mysql.com/33216))

   * When creating temporary tables within `Falcon', the tables are
     automatically created in the `FALCON_TEMPORARY' tablespace. If you
     specify an alternate tablespace to the *Note `CREATE TABLE':
     create-table. statement a warning will now be issued to that
     effect.  (Bug#33211 (http://bugs.mysql.com/33211))

   * Granting the `UPDATE' privilege on one column of a view caused the
     server to crash.  (Bug#33201 (http://bugs.mysql.com/33201))

   * For *Note `DECIMAL': numeric-types. columns used with the
     `ROUND(X,D)' or `TRUNCATE(X,D)' function with a non-constant value
     of D, adding an `ORDER BY' for the function result produced
     misordered output.  (Bug#33143 (http://bugs.mysql.com/33143)) See
     also Bug#33402 (http://bugs.mysql.com/33402), Bug#30617
     (http://bugs.mysql.com/30617).

   * Some valid *Note `SELECT': select. statements could not be used as
     views due to incorrect column reference resolution.  (Bug#33133
     (http://bugs.mysql.com/33133))

   * The weight for supplementary Unicode characters should be
     `0xFFFD', but the `WEIGHT_STRING()' function returned `0x0DC6'
     instead.  (Bug#33077 (http://bugs.mysql.com/33077))

   * The `CSV' engine did not honor update requests for *Note `BLOB':
     blob. columns when the new column value had the same length as the
     value to be updated.  (Bug#33067 (http://bugs.mysql.com/33067))

   * After receiving a `SIGHUP' signal, the server could crash, and
     user-specified log options were ignored when reopening the logs.
     (Bug#33065 (http://bugs.mysql.com/33065))

   * Repeatedly executing a query with a semi-join subquery could cause
     a server crash.  (Bug#33062 (http://bugs.mysql.com/33062))

   * The fix for Bug#11230 (http://bugs.mysql.com/11230) and Bug#26215
     (http://bugs.mysql.com/26215) introduced a significant
     input-parsing slowdown for the *Note `mysql': mysql. client.  This
     has been corrected.  (Bug#33057 (http://bugs.mysql.com/33057))

   * When MySQL was built with OpenSSL, the SSL library was not
     properly initialized with information of which endpoint it was
     (server or client), causing connection failures.  (Bug#33050
     (http://bugs.mysql.com/33050))

   * Under some circumstances a combination of aggregate functions and
     `GROUP BY' in a *Note `SELECT': select. query over a view could
     lead to incorrect calculation of the result type of the aggregate
     function. This in turn could lead to incorrect results, or to
     crashes on debug builds of the server.  (Bug#33049
     (http://bugs.mysql.com/33049))

   * It was not possible to set the value of `falcon_consistent_read'
     within the local scope. You can now set the global value, using
     *Note `SET GLOBAL': set-option, but this affects only the current
     local scope and all new connections made after the global variable
     was set.  (Bug#33041 (http://bugs.mysql.com/33041))

   * The new index condition pushdown optimization could cause a server
     crash when used with the range access method over an `InnoDB'
     table.  (Bug#33033 (http://bugs.mysql.com/33033))

   * For `DISTINCT' queries, 4.0 and 4.1 stopped reading joined tables
     as soon as the first matching row was found. However, this
     optimization was lost in MySQL 5.0, which instead read all
     matching rows. This fix for this regression may result in a major
     improvement in performance for `DISTINCT' queries in cases where
     many rows match.  (Bug#32942 (http://bugs.mysql.com/32942))

   * Repeated creation and deletion of views within prepared statements
     could eventually crash the server.  (Bug#32890
     (http://bugs.mysql.com/32890)) See also Bug#34587
     (http://bugs.mysql.com/34587).

   * The correct data type for a `NULL' column resulting from a *Note
     `UNION': union. could be determined incorrectly in some cases: 1)
     Not correctly inferred as `NULL' depending on the number of
     selects; 2) Not inferred correctly as `NULL' if one select used a
     subquery.  (Bug#32848 (http://bugs.mysql.com/32848))

   * For queries containing `GROUP_CONCAT(DISTINCT COL_LIST ORDER BY
     COL_LIST)', there was a limitation that the `DISTINCT' columns had
     to be the same as `ORDER BY' columns. Incorrect results could be
     returned if this was not true.  (Bug#32798
     (http://bugs.mysql.com/32798))

   * Incorrect assertions could cause a server crash for *Note
     `DELETE': delete. triggers for transactional tables.  (Bug#32790
     (http://bugs.mysql.com/32790))

   * *Note `SHOW EVENTS': show-events. and selecting from the *Note
     `INFORMATION_SCHEMA.EVENTS': events-table. table failed if the
     current database was `INFORMATION_SCHEMA'.  (Bug#32775
     (http://bugs.mysql.com/32775))

   * In some cases where setting a system variable failed, no error was
     sent to the client, causing the client to hang.  (Bug#32757
     (http://bugs.mysql.com/32757))

   * Enabling the `PAD_CHAR_TO_FULL_LENGTH' SQL mode caused
     privilege-loading operations (such as *Note `FLUSH PRIVILEGES':
     flush.) to include trailing spaces from grant table values stored
     in *Note `CHAR': char.  columns. Authentication for incoming
     connections failed as a result. Now privilege loading does not
     include trailing spaces, regardless of SQL mode.  (Bug#32753
     (http://bugs.mysql.com/32753))

   * Use of the `cp932' character set with `CAST()' in an `ORDER BY'
     clause could cause a server crash.  (Bug#32726
     (http://bugs.mysql.com/32726))

   * The *Note `SHOW ENGINE INNODB STATUS': show-engine. and *Note
     `SHOW ENGINE INNODB MUTEX': show-engine. statements incorrectly
     required the `SUPER' privilege rather than the `PROCESS' privilege.
     (Bug#32710 (http://bugs.mysql.com/32710))

   * Inserting strings with a common prefix into a table that used the
     `ucs2' character set corrupted the table.  (Bug#32705
     (http://bugs.mysql.com/32705))

   * A subquery using an `IS NULL' check of a column defined as `NOT
     NULL' in a table used in the `FROM' clause of the outer query
     produced an invalid result.  (Bug#32694
     (http://bugs.mysql.com/32694))

   * Specifying a non-existent column for an *Note `INSERT DELAYED':
     insert-delayed. statement caused a server crash rather than
     producing an error.  (Bug#32676 (http://bugs.mysql.com/32676))

   * Tables in the `mysql' database that stored the current `sql_mode'
     value as part of stored program definitions were not updated with
     newer mode values (`NO_ENGINE_SUBSTITUTION',
     `PAD_CHAR_TO_FULL_LENGTH'). This causes various problems defining
     stored programs if those modes were included in the current
     `sql_mode' value.  (Bug#32633 (http://bugs.mysql.com/32633))

   * Use of `CLIENT_MULTI_QUERIES' caused `libmysqld' to crash.
     (Bug#32624 (http://bugs.mysql.com/32624))

   * A `SELECT ... GROUP BY BIT_COLUMN' query failed with an assertion
     if the length of the *Note `BIT': numeric-types. column used for
     the `GROUP BY' was not an integer multiple of 8.  (Bug#32556
     (http://bugs.mysql.com/32556))

   * A view created with a string literal for one of the columns picked
     up the connection character set, but not the collation.
     Comparison to that field therefore used the default collation for
     that character set, causing an error if the connection collation
     was not compatible with the default collation. The problem was
     caused by text literals in a view being dumped with a character
     set introducer even when this was not necessary, sometimes leading
     to a loss of collation information. Now the character set
     introducer is dumped only if it was included in the original query.
     (Bug#32538 (http://bugs.mysql.com/32538)) See also Bug#21505
     (http://bugs.mysql.com/21505).

   * Using `SELECT INTO OUTFILE' with 8-bit `ENCLOSED BY' characters
     led to corrupted data when the data was reloaded using LOAD DATA
     INFILE. This was because `SELECT INTO OUTFILE' failed to escape
     the 8-bit characters.  (Bug#32533 (http://bugs.mysql.com/32533))

   * For *Note `FLUSH TABLES WITH READ LOCK': flush, the server failed
     to properly detect write-locked tables when running with
     low-priority updates, resulting in a crash or deadlock.
     (Bug#32528 (http://bugs.mysql.com/32528))

   * Queries using `LIKE' on tables having indexed *Note `CHAR': char.
     columns using either of the `eucjpms' or `ujis' character sets did
     not return correct results.  (Bug#32510
     (http://bugs.mysql.com/32510))

   * A query of the form `SELECT @USER_VARIABLE := CONSTANT AS ALIAS
     FROM TABLE GROUP BY ALIAS WITH ROLLUP' crashed the server.
     (Bug#32482 (http://bugs.mysql.com/32482))

   * Sending several *Note `KILL QUERY': kill. statements to target a
     connection running `SELECT SLEEP()' could freeze the server.
     (Bug#32436 (http://bugs.mysql.com/32436))

   * `ssl-cipher' values in option files were not being read by
     `libmysqlclient'.  (Bug#32429 (http://bugs.mysql.com/32429))

   * Repeated execution of a query containing a *Note `CASE':
     case-statement.  expression and numerous `AND' and `OR' relations
     could crash the server. The root cause of the issue was determined
     to be that the internal `SEL_ARG' structure was not properly
     initialized when created.  (Bug#32403
     (http://bugs.mysql.com/32403))

   * Referencing within a subquery an alias used in the *Note `SELECT':
     select. list of the outer query was incorrectly permitted.
     (Bug#32400 (http://bugs.mysql.com/32400))

   * If a global read lock acquired with *Note `FLUSH TABLES WITH READ
     LOCK': flush. was in effect, executing *Note `ALTER TABLE':
     alter-table. could cause a server crash.  (Bug#32395
     (http://bugs.mysql.com/32395))

   * `utf16' columns allowed incorrect Unicode characters inserted
     through conversion from another Unicode character set.  (Bug#32393
     (http://bugs.mysql.com/32393))

   * An `ORDER BY' query on a view created using a `FEDERATED' table as
     a base table caused the server to crash.  (Bug#32374
     (http://bugs.mysql.com/32374))

   * The *Note `mysqldump': mysqldump. utility did not print enough
     version information about itself at the top of its output. The
     output now shows the same information as *Note `mysqldump':
     mysqldump. invoked with the `-V' option, namely the *Note
     `mysqldump': mysqldump. version number, the MySQL server version,
     and the distribution.  (Bug#32350 (http://bugs.mysql.com/32350))

   * Comparison of a `BIGINT NOT NULL' column with a constant
     arithmetic expression that evaluated to NULL mistakenly caused the
     error `Column '...' cannot be null' (error 1048).  (Bug#32335
     (http://bugs.mysql.com/32335))

   * Assigning a 65,536-byte string to a *Note `TEXT': blob. column
     (which can hold a maximum of 65,535 bytes) resulted in truncation
     without a warning. Now a truncation warning is generated.
     (Bug#32282 (http://bugs.mysql.com/32282))

   * The `LAST_DAY()' function returns a *Note `DATE': datetime. value,
     but internally the value did not have the time fields zeroed and
     calculations involving the value could return incorrect results.
     (Bug#32270 (http://bugs.mysql.com/32270))

   * `MIN()' and `MAX()' could return incorrect results when an index
     was present if a loose index scan was used.  (Bug#32268
     (http://bugs.mysql.com/32268))

   * Executing a prepared statement associated with a materialized
     cursor sent to the client a metadata packet with incorrect table
     and database names. The problem occurred because the server sent
     the name of the temporary table used by the cursor instead of the
     table name of the original table.

     The same problem occured when selecting from a view, in which case
     the name of the table name was sent, rather than the name of the
     view.  (Bug#32265 (http://bugs.mysql.com/32265))

   * Memory corruption could occur due to large index map in `Range
     checked for each record' status reported by *Note `EXPLAIN
     SELECT': explain. The problem was based in an incorrectly
     calculated length of the buffer used to store a hexadecimal
     representation of an index map, which could result in buffer
     overrun and stack corruption under some circumstances.  (Bug#32241
     (http://bugs.mysql.com/32241))

   * Various test program cleanups were made: 1) `mytest' and
     `libmysqltest' were removed. 2) `bug25714' displays an error
     message when invoked with incorrect arguments or the `--help'
     option. 3) `mysql_client_test' exits cleanly with a proper error
     status.  (Bug#32221 (http://bugs.mysql.com/32221))

   * The default grant tables on Windows contained information for host
     `production.mysql.com', which should not be there.  (Bug#32219
     (http://bugs.mysql.com/32219))

   * For comparisons of the form DATE_COL OP DATETIME_CONST (where OP is
     `=', `<', `>', `<=', or `>='), the comparison is done using *Note
     `DATETIME': datetime. values, per the fix for Bug#27590
     (http://bugs.mysql.com/27590). However that fix caused any index on
     DATE_COL not to be used and compromised performance. Now the index
     is used again.  (Bug#32198 (http://bugs.mysql.com/32198))

   * *Note `DATETIME': datetime. arguments specified in numeric form
     were treated by `DATE_ADD()' as *Note `DATE': datetime. values.
     (Bug#32180 (http://bugs.mysql.com/32180))

   * When `configure' was run with `--with-libevent', `libevent' was
     not linked statically with *Note `mysqld': mysqld, preventing
     *Note `mysqld': mysqld. from being run with a debugger.
     (Bug#32156 (http://bugs.mysql.com/32156))

   * `InnoDB' adaptive hash latches could be held too long, resulting
     in a server crash. This fix may also provide significant
     performance improvements on systems on which many queries using
     filesorts with temporary tables are being performed.  (Bug#32149
     (http://bugs.mysql.com/32149))

   * Killing a statement could lead to a race condition in the server.
     (Bug#32148 (http://bugs.mysql.com/32148))

   * String-to-double conversion was performed differently when the
     prepared-statement protocol was used from when it was not.
     (Bug#32095 (http://bugs.mysql.com/32095))

   * With `lower_case_table_names' set, `CREATE TABLE LIKE' was treated
     differently by `libmysqld' than by the non-embedded server.
     (Bug#32063 (http://bugs.mysql.com/32063))

   * On Windows, `mysqltest_embedded.exe' did not properly execute the
     `send' command.  (Bug#32044 (http://bugs.mysql.com/32044))

   * Within a subquery, *Note `UNION': union. was handled differently
     than at the top level, which could result in incorrect results or
     a server crash.  (Bug#32036 (http://bugs.mysql.com/32036),
     Bug#32051 (http://bugs.mysql.com/32051))

   * `HOUR()', `MINUTE()', and `SECOND()' could return non-zero values
     for *Note `DATE': datetime. arguments.  (Bug#31990
     (http://bugs.mysql.com/31990))

   * A variable named `read_only' could be declared even though that is
     a reserved word.  (Bug#31947 (http://bugs.mysql.com/31947))

   * On Windows, the build process failed with four parallel build
     threads.  (Bug#31929 (http://bugs.mysql.com/31929))

   * Changing the SQL mode to cause dates with `zero' parts to be
     considered invalid (such as `'1000-00-00'') could result in
     indexed and non-indexed searches returning different results for a
     column that contained such dates.  (Bug#31928
     (http://bugs.mysql.com/31928))

   * The server used unnecessarily large amounts of memory when user
     variables were used as an argument to `CONCAT()' or `CONCAT_WS()'.
     (Bug#31898 (http://bugs.mysql.com/31898))

   * Queries testing numeric constants containing leading zeroes
     against `ZEROFILL' columns were not evaluated correctly.
     (Bug#31887 (http://bugs.mysql.com/31887))

   * `mysql-test-run.pl' sometimes set up test scenarios in which the
     same port number was passed to multiple servers, causing one of
     them to be unable to start.  (Bug#31880
     (http://bugs.mysql.com/31880))

   * Using `ORDER BY' led to the wrong result when using the `ARCHIVE'
     on a table with a *Note `BLOB': blob. when the table cache was
     full. The table could also be reported as crashed after the query
     had completed, even though the table data was intact.  (Bug#31833
     (http://bugs.mysql.com/31833))

   * Name resolution for correlated subqueries and `HAVING' clauses
     failed to distinguish which of two was being performed when there
     was a reference to an outer aliased field. This could result in
     error messages about a `HAVING' clause for queries that had no such
     clause.  (Bug#31797 (http://bugs.mysql.com/31797))

   * If an error occurred during file creation, the server sometimes
     did not remove the file, resulting in an unused file in the file
     system.  (Bug#31781 (http://bugs.mysql.com/31781))

   * The *Note `mysqld': mysqld. crash handler failed on Windows.
     (Bug#31745 (http://bugs.mysql.com/31745))

   * *Note `mysqlslap': mysqlslap. failed to commit after the final
     record load.  (Bug#31704 (http://bugs.mysql.com/31704))

   * `ucs2' does not work as a client character set, but attempts to
     use it as such were not rejected. Now `character_set_client'
     cannot be set to `ucs2'. This also affects statements such as `SET
     NAMES' and `SET CHARACTER SET'.  (Bug#31615
     (http://bugs.mysql.com/31615))

   * The server returned the error message `Out of memory; restart
     server and try again' when the actual problem was that the sort
     buffer was too small. Now an appropriate error message is returned
     in such cases.  (Bug#31590 (http://bugs.mysql.com/31590))

   * For a table that had been opened with *Note `HANDLER': handler.
     and marked for reopening after being closed with *Note `FLUSH
     TABLES': flush, *Note `DROP TABLE': drop-table. did not properly
     discard the handler.  (Bug#31397 (http://bugs.mysql.com/31397))

   * A table having an index that included a *Note `BLOB': blob. or
     *Note `TEXT': blob. column, and that was originally created with a
     MySQL server using version 4.1 or earlier, could not be opened by
     a 5.1 or later server.  (Bug#31331 (http://bugs.mysql.com/31331))

   * The `-', `*', and `/' operators and the functions `POW()' and
     `EXP()' could misbehave when used with floating-point numbers.
     Previously they might return `+INF', `-INF', or `NaN' in cases of
     numeric overflow (including that caused by division by zero) or
     when invalid arguments were used. Now `NULL' is returned in all
     such cases.  (Bug#31236 (http://bugs.mysql.com/31236))

   * The *Note `mysql_change_user()': mysql-change-user. C API function
     caused global `Com_XXX' status variable values to be incorrect.
     (Bug#31222 (http://bugs.mysql.com/31222))

   * When sorting privilege table rows, the server treated escaped
     wildcard characters (`\%' and `\_') the same as unescaped wildcard
     characters (`%' and `_'), resulting in incorrect row ordering.
     (Bug#31194 (http://bugs.mysql.com/31194))

   * Server variables could not be set to their current values on Linux
     platforms. (Additional fixes were made in MySQL 6.0.9 and 6.0.10.)
     (Bug#31177 (http://bugs.mysql.com/31177)) See also Bug#6958
     (http://bugs.mysql.com/6958).

   * Data in *Note `BLOB': blob. or `GEOMETRY' columns could be cropped
     when performing a *Note `UNION': union. query.  (Bug#31158
     (http://bugs.mysql.com/31158))

   * The server crashed in the parser when running out of memory.
     Memory handling in the parser has been improved to gracefully
     return an error when out-of-memory conditions occur in the parser.
     (Bug#31153 (http://bugs.mysql.com/31153))

   * MySQL declares a `UNIQUE' key as a `PRIMARY' key if it doesn't have
     `NULL' columns and is not a partial key, and the `PRIMARY' key
     must alway be the first key.  However, in some cases, a non-first
     key could be reported as `PRIMARY', leading to an assert failure by
     `InnoDB'. This is fixed by correcting the key sort order.
     (Bug#31137 (http://bugs.mysql.com/31137))

   * Many nested subqueries in a single query could led to excessive
     memory consumption and possibly a crash of the server.  (Bug#31048
     (http://bugs.mysql.com/31048))

   * An assertion failure occurred for queries containing two
     subqueries if both subqueries were evaluated using a semi-join
     strategy.  (Bug#31040 (http://bugs.mysql.com/31040))

   * On Windows, *Note `SHOW PROCESSLIST': show-processlist.  could
     display process entries with a `State' value of `*** DEAD ***'.
     (Bug#30960 (http://bugs.mysql.com/30960))

   * `ROUND(X,D)' or `TRUNCATE(X,D)' for non-constant values of D could
     crash the server if these functions were used in an `ORDER BY'
     that was resolved using `filesort'.  (Bug#30889
     (http://bugs.mysql.com/30889))

   * Resetting the query cache by issuing a `SET GLOBAL
     query_cache_size=0' statement caused the server to crash if it
     concurrently was saving a new result set to the query cache.
     (Bug#30887 (http://bugs.mysql.com/30887))

   * Manifest problems prevented `MySQLInstanceConfig.exe' from running
     on Windows Vista.  (Bug#30823 (http://bugs.mysql.com/30823))

   * The optimizer incorrectly optimized conditions out of the `WHERE'
     clause in some queries involving subqueries and indexed columns.
     (Bug#30788 (http://bugs.mysql.com/30788))

   * If an alias was used to refer to the value returned by a stored
     function within a subselect, the outer select recognized the alias
     but failed to retrieve the value assigned to it in the subselect.
     (Bug#30787 (http://bugs.mysql.com/30787))

   * Improper calculation of `CASE' expression results could lead to
     value truncation.  (Bug#30782 (http://bugs.mysql.com/30782))

   * The `thread_handling' system variable was treated as having a
     `SESSION' value and as being settable at runtime. Now it has only a
     `GLOBAL' read-only value.  (Bug#30651
     (http://bugs.mysql.com/30651))

   * If the optimizer used a Multi-Range Read access method for index
     lookups, incorrect results could occur for rows that contained any
     of the *Note `BLOB': blob. or *Note `TEXT': blob. data types.
     (Bug#30622 (http://bugs.mysql.com/30622))

   * Binary logging for a stored procedure differed depending on
     whether or not execution occurred in a prepared statement.
     (Bug#30604 (http://bugs.mysql.com/30604))

   * When casting a string value to an integer, cases where the input
     string contained a decimal point and was long enough to overrun
     the `unsigned long long' type were not handled correctly. The
     position of the decimal point was not taken into account which
     resulted in miscalculated numbers and incorrect truncation to
     appropriate SQL data type limits.  (Bug#30453
     (http://bugs.mysql.com/30453))

   * With `libmysqld', use of prepared statements and the query cache
     at the same time caused problems.  (Bug#30430
     (http://bugs.mysql.com/30430))

   * For `CREATE ... SELECT ... FROM', where the resulting table
     contained indexes, adding `SQL_BUFFER_RESULT' to the *Note
     `SELECT': select. part caused index corruption in the table.
     (Bug#30384 (http://bugs.mysql.com/30384))

   * An orphaned PID file from a no-longer-running process could cause
     *Note `mysql.server': mysql-server. to wait for that process to
     exit even though it does not exist.  (Bug#30378
     (http://bugs.mysql.com/30378))

   * The optimizer made incorrect assumptions about the value of the
     `is_member' value for user-defined functions, sometimes resulting
     in incorrect ordering of UDF results.  (Bug#30355
     (http://bugs.mysql.com/30355))

   * The `Table_locks_waited' waited variable was not incremented in
     the cases that a lock had to be waited for but the waiting thread
     was killed or the request was aborted.  (Bug#30331
     (http://bugs.mysql.com/30331))

   * Simultaneous *Note `ALTER TABLE': alter-table.  statements for
     `BLACKHOLE' tables caused 100% CPU use due to locking problems.
     (Bug#30294 (http://bugs.mysql.com/30294))

   * Tables with a `GEOMETRY' column could be marked as corrupt if you
     added a non-`SPATIAL' index on a `GEOMETRY' column.  (Bug#30284
     (http://bugs.mysql.com/30284))

   * Flushing a merge table between the time it was opened and its
     child table were actually attached caused the server to crash.
     (Bug#30273 (http://bugs.mysql.com/30273)) This regression was
     introduced by Bug#26379 (http://bugs.mysql.com/26379).

   * The `Com_create_function' status variable was not incremented
     properly.  (Bug#30252 (http://bugs.mysql.com/30252))

   * For Multi-Range Read scans used to resolve `LIMIT' queries,
     failure to close the scan caused file descriptor leaks for `MyISAM'
     tables.  (Bug#30221 (http://bugs.mysql.com/30221))

   * View metadata returned from *Note `INFORMATION_SCHEMA.VIEWS':
     views-table. was changed by the fix for Bug#11986
     (http://bugs.mysql.com/11986), causing the information returned in
     MySQL 5.1 to differ from that returned in 5.0.  (Bug#30217
     (http://bugs.mysql.com/30217))

   * If the server crashed during an *Note `ALTER TABLE': alter-table.
     statement, leaving a temporary file in the database directory, a
     subsequent *Note `DROP DATABASE': drop-database. statement failed
     due to the presence of the temporary file.  (Bug#30152
     (http://bugs.mysql.com/30152))

   * The parser accepted an `INTO' clause in nested *Note `SELECT':
     select. statements, which is invalid because such statements must
     return their results to the outer context.  (Bug#30105
     (http://bugs.mysql.com/30105), Bug#33204
     (http://bugs.mysql.com/33204))

   * For tables with *Note `FLOAT': numeric-types. or *Note `DOUBLE':
     numeric-types. columns, *Note `CHECKSUM TABLE': checksum-table.
     could report different results on master and slave servers.
     (Bug#30041 (http://bugs.mysql.com/30041))

   * *Note `mysqld': mysqld. displayed the `--enable-pstack' option in
     its help message even if MySQL was configured without
     `--with-pstack'.  (Bug#29836 (http://bugs.mysql.com/29836))

   * The *Note `mysql_config': mysql-config. command would output
     `CFLAGS' values that were incompatible with C++ for the HP-UX
     platform.  (Bug#29645 (http://bugs.mysql.com/29645))

   * Views were treated as insertable even if some base table columns
     with no default value were omitted from the view definition.
     (This is contrary to the condition for insertability that a view
     must contain all columns in the base table that do not have a
     default value.)  (Bug#29477 (http://bugs.mysql.com/29477))

   * *Note `myisamchk': myisamchk. always reported the character set
     for a table as `latin1_swedish_ci (8)' regardless of the table'
     actual character set.  (Bug#29182 (http://bugs.mysql.com/29182))

   * Denormalized double-precision numbers cannot be handled properly
     by old MIPS pocessors. For IRIX, this is now handled by enabling a
     mode to use a software workaround.  (Bug#29085
     (http://bugs.mysql.com/29085))

   * When doing a *Note `DELETE': delete. on a table that involved a
     `JOIN' with `MyISAM' or `MERGE' tables and the `JOIN' referred to
     the same table, the operation could fail reporting `ERROR 1030
     (HY000): Got error 134 from storage engine'. This was because scans
     on the table contents would change because of rows that had
     already been deleted.  (Bug#28837 (http://bugs.mysql.com/28837))

   * *Note `SHOW VARIABLES': show-variables. did not correctly display
     the value of the `thread_handling' system variable.  (Bug#28785
     (http://bugs.mysql.com/28785))

   * When running the MySQL Instance Configuration Wizard, a race
     condition could exist that would fail to connect to a newly
     configured instance. This was because *Note `mysqld': mysqld.  had
     not completed the startup process before the next stage of the
     installation process.  (Bug#28628 (http://bugs.mysql.com/28628))

   * For upgrading to a new major version using RPM packages (such as
     4.1 to 5.0), if the installation procedure found an existing MySQL
     server running, it could fail to shut down the old server, but
     also erroneously removed the server's socket file. Now the
     procedure checks for an existing server package from a different
     vendor or major MySQL version. In such case, it refuses to install
     the server and recommends how to safely remove the old packages
     before installing the new ones.  (Bug#28555
     (http://bugs.mysql.com/28555))

   * *Note `mysqlhotcopy': mysqlhotcopy. silently skipped databases with
     names consisting of two alphanumeric characters.  (Bug#28460
     (http://bugs.mysql.com/28460))

   * No information was written to the general query log for the
     `COM_STMT_CLOSE', `COM_STMT_RESET', and `COM_STMT_SEND_LONG_DATA'
     commands. (These occur when a client invokes the *Note
     `mysql_stmt_close()': mysql-stmt-close, *Note
     `mysql_stmt_reset()': mysql-stmt-reset. and *Note
     `mysql_stmt_send_long_data()': mysql-stmt-send-long-data. C API
     functions.)  (Bug#28386 (http://bugs.mysql.com/28386))

   * Previously, the parser accepted the ODBC `{ OJ ... LEFT OUTER JOIN
     ...}' syntax for writing left outer joins.  The parser now allows
     `{ OJ ... }' to be used to write other types of joins, such as
     `INNER JOIN' or `RIGHT OUTER JOIN'. This helps with compatibility
     with some third-party applications, but is not official ODBC
     syntax.  (Bug#28317 (http://bugs.mysql.com/28317))

   * The `FEDERATED' storage engine did not perform identifier quoting
     for column names that are reserved words when sending statements
     to the remote server.  (Bug#28269 (http://bugs.mysql.com/28269))

   * The SQL parser did not accept an empty `UNION=()' clause. This
     meant that, when there were no underlying tables specified for a
     `MERGE' table, *Note `SHOW CREATE TABLE': show-create-table. and
     *Note `mysqldump': mysqldump. both output statements that could
     not be executed.

     Now it is possible to execute a *Note `CREATE TABLE':
     create-table. or *Note `ALTER TABLE': alter-table.  statement with
     an empty `UNION=()' clause.  However, *Note `SHOW CREATE TABLE':
     show-create-table. and *Note `mysqldump': mysqldump. do not output
     the `UNION=()' clause if there are no underlying tables specified
     for a `MERGE' table. This also means it is now possible to remove
     the underlying tables for a `MERGE' table using `ALTER TABLE ...
     UNION=()'.  (Bug#28248 (http://bugs.mysql.com/28248))

   * An `ORDER BY' at the end of a *Note `UNION': union. affected
     individual *Note `SELECT': select. statements rather than the
     overall query result.  (Bug#27848 (http://bugs.mysql.com/27848))

   * It was possible to exhaust memory by repeatedly running
     `index_merge' queries and never performing any *Note `FLUSH
     TABLES': flush. statements.  (Bug#27732
     (http://bugs.mysql.com/27732))

   * When `utf8' was set as the connection character set, using
     `SPACE()' with a non-Unicode column produced an error.  (Bug#27580
     (http://bugs.mysql.com/27580)) See also Bug#23637
     (http://bugs.mysql.com/23637).

   * A race condition between killing a statement and the thread
     executing the statement could lead to a situation such that the
     binary log contained an event indicating that the statement was
     killed, whereas the statement actually executed to completion.
     (Bug#27571 (http://bugs.mysql.com/27571))

   * Some queries using the `NAME_CONST()' function failed to return
     either a result or an error to the client, causing it to hang.
     This was due to the fact that there was no check to insure that
     both arguments to this function were constant expressions.
     (Bug#27545 (http://bugs.mysql.com/27545), Bug#32559
     (http://bugs.mysql.com/32559))

   * Evaluation of an `IN()' predicate containing a decimal-valued
     argument caused a server crash.  (Bug#27513
     (http://bugs.mysql.com/27513), Bug#27362
     (http://bugs.mysql.com/27362), CVE-2007-2583
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2583))

   * With the `read_only' system variable enabled, *Note `CREATE
     DATABASE': create-database.  and *Note `DROP DATABASE':
     drop-database. were allowed to users who did not have the `SUPER'
     privilege.  (Bug#27440 (http://bugs.mysql.com/27440))

   * The parser rules for the *Note `SHOW PROFILE': show-profile.
     statement were revised to work with older versions of `bison'.
     (Bug#27433 (http://bugs.mysql.com/27433))

   * *Note `resolveip': resolveip. failed to produce correct results
     for host names that begin with a digit.  (Bug#27427
     (http://bugs.mysql.com/27427))

   * In `ORDER BY' clauses, mixing aggregate functions and non-grouping
     columns is not allowed if the `ONLY_FULL_GROUP_BY' SQL mode is
     enabled. However, in some cases, no error was thrown because of
     insufficient checking.  (Bug#27219 (http://bugs.mysql.com/27219))

   * For the `--record_log_pos' option, *Note `mysqlhotcopy':
     mysqlhotcopy. now determines the slave status information from the
     result of *Note `SHOW SLAVE STATUS': show-slave-status. by using
     the `Relay_Master_Log_File' and `Exec_Master_Log_Pos' values
     rather than the `Master_Log_File' and `Read_Master_Log_Pos'
     values. This provides a more accurate indication of slave
     execution relative to the master.  (Bug#27101
     (http://bugs.mysql.com/27101))

   * Memory corruption, a crash of the MySQL server, or both, could
     take place if a low-level I/O error occurred while an `ARCHIVE'
     table was being opened.  (Bug#26978 (http://bugs.mysql.com/26978))

   * *Note `SHOW PROFILE': show-profile. hung if executed before
     enabling the `@@profiling' session variable.  (Bug#26938
     (http://bugs.mysql.com/26938))

   * The *Note `mysql_insert_id()': mysql-insert-id. C API function
     sometimes returned different results for `libmysqld' and
     `libmysqlclient'.  (Bug#26921 (http://bugs.mysql.com/26921))

   * Symbolic links on Windows could fail to work.  (Bug#26811
     (http://bugs.mysql.com/26811))

   * *Note `mysqld': mysqld. sometimes miscalculated the number of
     digits required when storing a floating-point number in a *Note
     `CHAR': char. column. This caused the value to be truncated, or
     (when using a debug build) caused the server to crash.  (Bug#26788
     (http://bugs.mysql.com/26788)) See also Bug#12860
     (http://bugs.mysql.com/12860).

   * The default database is no longer changed to `NULL' (`no
     database') if *Note `DROP DATABASE': drop-database. for that
     database failed.  (Bug#26704 (http://bugs.mysql.com/26704))

   * *Note `DROP DATABASE': drop-database. failed for attempts to drop
     databases with names that contained the legacy `#mysql50#' name
     prefix.  (Bug#26703 (http://bugs.mysql.com/26703))

   * `config-win.h' unconditionally defined `bool' as *Note `BOOL':
     numeric-types, causing problems on systems where `bool' is 1 byte
     and *Note `BOOL': numeric-types. is 4 bytes.  (Bug#26461
     (http://bugs.mysql.com/26461))

   * It makes no sense to attempt to use `ALTER TABLE ...  ORDER BY' to
     order an `InnoDB' table if there is a user-defined clustered
     index, because rows are always ordered by the clustered index.
     Such attempts now are ignored and produce a warning.

     Also, in some cases, `InnoDB' incorrectly used a secondary index
     when the clustered index would produce a faster scan. *Note
     `EXPLAIN': explain. output now indicates use of the clustered
     index (for tables that have one) as lines with a `type' value of
     `index', a `key' value of `PRIMARY', and without `Using index' in
     the `Extra' value.  (Bug#26447 (http://bugs.mysql.com/26447)) See
     also Bug#35850 (http://bugs.mysql.com/35850).

   * On Windows, for distributions built with debugging support, *Note
     `mysql': mysql. could crash if the user typed Control-C.
     (Bug#26243 (http://bugs.mysql.com/26243))

   * When symbolic links were disabled, either with a server startup
     option or by enabling the `NO_DIR_IN_CREATE' SQL mode, *Note
     `CREATE TABLE': create-table. silently ignored the `DATA
     DIRECTORY' and `INDEX DIRECTORY' table options. Now the server
     issues a warning if symbolic links are disabled when these table
     options are used.  (Bug#25677 (http://bugs.mysql.com/25677))

   * `CREATE TABLE LIKE' did not work when the source table was an
     `INFORMATION_SCHEMA' table.  (Bug#25629
     (http://bugs.mysql.com/25629))

   * Attempting to create an index with a prefix on a *Note `DECIMAL':
     numeric-types. column appeared to succeed with an inaccurate
     warning message. Now, this action fails with the error `Incorrect
     prefix key; the used key part isn't a string, the used length is
     longer than the key part, or the storage engine doesn't support
     unique prefix keys'.  (Bug#25426 (http://bugs.mysql.com/25426))

   * *Note `mysqlcheck -A -r': mysqlcheck. did not correctly identify
     all tables that needed repairing.  (Bug#25347
     (http://bugs.mysql.com/25347))

   * On Windows, an error in `configure.js' caused installation of
     source distributions to fail.  (Bug#25340
     (http://bugs.mysql.com/25340))

   * The `Qcache_free_blocks' status variable did not display a value
     of 0 if the query cache was disabled.  (Bug#25132
     (http://bugs.mysql.com/25132))

   * The client library had no way to return an error if no connection
     had been established. This caused problems such as *Note
     `mysql_library_init()': mysql-library-init. failing silently if no
     `errmsg.sys' file was available.  (Bug#25097
     (http://bugs.mysql.com/25097))

   * For Windows 64-bit builds, enabling shared-memory support caused
     client connections to fail.  (Bug#24992
     (http://bugs.mysql.com/24992))

   * If the expected precision of an arithmetic expression exceeded the
     maximum precision supported by MySQL, the precision of the result
     was reduced by an unpredictable or arbitrary amount, rather than
     to the maximum precision. In some cases, exceeding the maximum
     supported precision could also lead to a crash of the server.
     (Bug#24907 (http://bugs.mysql.com/24907))

   * *Note `mysql': mysql. did not use its completion table. Also, the
     table contained few entries.  (Bug#24624
     (http://bugs.mysql.com/24624))

   * `Data truncated for column COL_NUM at row ROW_NUM' warnings were
     generated for some (constant) values that did not have too high
     precision.  (Bug#24541 (http://bugs.mysql.com/24541))

   * If a user installed MySQL Server and set a password for the `root'
     user, and then uninstalled and reinstalled MySQL Server to the
     same location, the user could not use the MySQL Instance Config
     wizard to configure the server because the uninstall operation
     left the previous data directory intact. The config wizard
     _assumed_ that any new install (not an upgrade) would have the
     default data directory where the `root' user has no password. The
     installer now writes a registry key named `FoundExistingDataDir'.
     If the installer finds an existing data directory, the key will
     have a value of 1, otherwise it will have a value of 0. When
     `MySQLInstanceConfig.exe' is run, it will attempt to read the key.
     If it can read the key, and the value is 1 and there is no
     existing instance of the server (indicating a new installation),
     the Config Wizard will allow the user to input the old password so
     the server can be configured.  (Bug#24215
     (http://bugs.mysql.com/24215))

   * Logging of statements to log tables was incorrect for statements
     that contained `utf8'-incompatible binary strings. Incompatible
     sequences are hex-encoded now.  (Bug#23924
     (http://bugs.mysql.com/23924))

   * The MySQL header files contained some duplicate macro definitions
     that could cause compilation problems.  (Bug#23839
     (http://bugs.mysql.com/23839))

   * A *Note `CREATE TRIGGER': create-trigger. statement could cause a
     deadlock or server crash if it referred to a table for which a
     table lock had been acquired with *Note `LOCK TABLES': lock-tables.
     (Bug#23713 (http://bugs.mysql.com/23713))

   * *Note `SHOW COLUMNS': show-columns. on a `TEMPOARY' table caused
     locking issues.  (Bug#23588 (http://bugs.mysql.com/23588))

   * For distributions compiled with the bundled `libedit' library,
     there were difficulties using the *Note `mysql': mysql. client to
     enter input for non-ASCII or multi-byte characters.  (Bug#23097
     (http://bugs.mysql.com/23097))

   * *Note `perror': perror. reported incomplete or inaccurate
     information.  (Bug#23028 (http://bugs.mysql.com/23028), Bug#25177
     (http://bugs.mysql.com/25177))

   * After stopping and starting the event scheduler, disabled events
     could remain in the execution queue.  (Bug#22738
     (http://bugs.mysql.com/22738))

   * The server produced a confusing error message when attempting to
     open a table that required a storage engine that was not loaded.
     (Bug#22708 (http://bugs.mysql.com/22708))

   * The parser treated the `INTERVAL()' function incorrectly, leading
     to situations where syntax errors could result depending on which
     side of an arithmetic operator the function appeared.  (Bug#22312
     (http://bugs.mysql.com/22312))

   * For views or stored programs created with an invalid `DEFINER'
     value, the error message was confusing (did not tie the problem to
     the `DEFINER' clause) and has been improved.  (Bug#21854
     (http://bugs.mysql.com/21854))

   * Warnings for deprecated syntax constructs used in stored routines
     make sense to report only when the routine is being created, but
     they were also being reported when the routine was parsed for
     loading into the execution cache. Now they are reported only at
     routine creation time.  (Bug#21801 (http://bugs.mysql.com/21801))

   * Renaming a column that appeared in a foreign key definition did
     not update that definition with the new column name. This occurred
     with both referenced and referencing tables.  (Bug#21704
     (http://bugs.mysql.com/21704))

   * On Mac OS X, *Note `mysqld': mysqld. did not react to Ctrl-C when
     run under `gdb', even when run with the `--gdb' option.
     (Bug#21567 (http://bugs.mysql.com/21567))

   * When inserting an extraordinarly large value into a *Note
     `DOUBLE': numeric-types. column, the value could be truncated in
     such a way that the new value cannot be reloaded manually or from
     the output of *Note `mysqldump': mysqldump.  (Bug#21497
     (http://bugs.mysql.com/21497))

   * `CREATE ... SELECT' did not always set `DEFAULT' column values in
     the new table.  (Bug#21380 (http://bugs.mysql.com/21380))

   * *Note `mysql_config': mysql-config. output did not include
     `-lmygcc' on some platforms when it was needed.  (Bug#21158
     (http://bugs.mysql.com/21158))

   * `mysql-stress-test.pl' and `mysqld_multi.server.sh' were missing
     from some binary distributions.  (Bug#21023
     (http://bugs.mysql.com/21023), Bug#25486
     (http://bugs.mysql.com/25486))

   * It was possible to execute `CREATE TABLE t1 ... SELECT ... FROM
     t2' with the `CREATE' privilege for `t1' and `SELECT' privilege
     for `t2', even in the absence of the `INSERT' privilege for `t1'.
     (Bug#20901 (http://bugs.mysql.com/20901))

   * The `BENCHMARK()' function, invoked with more than 2147483648
     iterations (the size of a signed 32-bit integer), terminated
     prematurely.  (Bug#20752 (http://bugs.mysql.com/20752))

   * *Note `mysqldumpslow': mysqldumpslow. returned a confusing error
     message when no configuration file was found.  (Bug#20455
     (http://bugs.mysql.com/20455))

   * `MySQLInstanceConfig.exe' could lose the `innodb_data_home_dir'
     setting when reconfiguring an instance.  (Bug#19797
     (http://bugs.mysql.com/19797))

   * Issuing an SQL *Note `KILL': kill. of the active connection caused
     an error on Mac OS X.  (Bug#19723 (http://bugs.mysql.com/19723))

   * *Note `CREATE TABLE': create-table. allowed 0 as the default value
     for a *Note `TIMESTAMP': datetime.  column when the server was
     running in `NO_ZERO_DATE' mode.  (Bug#18834
     (http://bugs.mysql.com/18834))

   * The `-lmtmalloc' library was removed from the output of *Note
     `mysql_config': mysql-config. on Solaris, as it caused problems
     when building `DBD::mysql' (and possibly other applications) on
     that platform that tried to use `dlopen()' to access the client
     library.  (Bug#18322 (http://bugs.mysql.com/18322))

   * Use of *Note `GRANT': grant. statements with grant tables from an
     old version of MySQL could cause a server crash.  (Bug#16470
     (http://bugs.mysql.com/16470))

   * A `SET' column whose definition specified 64 elements could not be
     updated using integer values.  (Bug#15409
     (http://bugs.mysql.com/15409))

   * Zero-padding of exponent values was not the same across platforms.
     (Bug#12860 (http://bugs.mysql.com/12860))

   * If a *Note `SELECT': select. calls a stored function in a
     transaction, and a statement within the function fails, that
     statement should roll back. Furthermore, if *Note `ROLLBACK':
     commit. is executed after that, the entire transaction should be
     rolled back. Before this fix, the failed statement did not roll
     back when it failed (even though it might ultimately get rolled
     back by a *Note `ROLLBACK': commit.  later that rolls back the
     entire transaction).  (Bug#12713 (http://bugs.mysql.com/12713))
     See also Bug#34655 (http://bugs.mysql.com/34655).

   * The grammar for `GROUP BY', when used with `WITH CUBE' or `WITH
     ROLLUP', caused a conflict with the grammar for view definitions
     that included `WITH CHECK OPTION'.  (Bug#9801
     (http://bugs.mysql.com/9801))

   * The parser incorrectly allowed `SQLSTATE '00000'' to be specified
     for a condition handler. (This is incorrect because the condition
     must be a failure condition and `'00000'' indicates success.)
     (Bug#8759 (http://bugs.mysql.com/8759))

   * `MySQLInstanceConfig.exe' did not save the `innodb_data_home_dir'
     value to the `my.ini' file under certain circumstances.  (Bug#6627
     (http://bugs.mysql.com/6627))

   * *Note `RESTORE': restore. failed for databases or tables with
     names that contain certain non-alphanumeric characters, such as
     spaces.  (Bug#3353 (http://bugs.mysql.com/3353))

   * Grant table checks failed in `libmysqld'.


File: manual.info,  Node: news-6-0-4,  Next: news-6-0-3,  Prev: news-6-0-5,  Up: news-6-0-x

C.1.8 Changes in MySQL 6.0.4 (12 February 2008)
-----------------------------------------------

Functionality added or changed:

   * *Important Change*: *Partitioning*: *Security Fix*: It was
     possible, by creating a partitioned table using the `DATA
     DIRECTORY' and `INDEX DIRECTORY' options to gain privileges on
     other tables having the same name as the partitioned table. As a
     result of this fix, any table-level `DATA DIRECTORY' or `INDEX
     DIRECTORY' options are now ignored for partitioned tables.
     (Bug#32091 (http://bugs.mysql.com/32091), CVE-2007-5970
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-5970)) See
     also Bug#29325 (http://bugs.mysql.com/29325), Bug#32111
     (http://bugs.mysql.com/32111).

   * *Incompatible Change*: The Unicode implementation has been
     extended to provide support for supplementary characters that lie
     outside the Basic Multilingual Plane (BMP). Noteworthy features:

        * `utf16' and `utf32' character sets have been added. These
          correspond to the UTF-16 and UTF-32 encodings of the Unicode
          character set, and they both support supplementary characters.

        * The `utf8' character set from previous versions of MySQL has
          been renamed to `utf8mb3', to reflect that its encoding uses
          a maximum of three bytes for multi-byte characters.  (Old
          tables that previously used `utf8' will be reported as using
          `utf8mb3' after an in-place upgrade to MySQL 6.0, but
          otherwise work as before.)

        * The new `utf8' character set in MySQL 6.0 is similar to
          `utf8mb3', but its encoding allows up to four bytes per
          character to enable support for supplementary characters.

        * The `ucs2' character set is essentially unchanged except for
          the inclusion of some newer BMP characters.

     In most respects, upgrading from MySQL 5.1 to 6.0 should present
     few problems with regard to Unicode usage, although there are some
     potential areas of incompatibility. Some examples:

        * For the variable-length character data types (*Note
          `VARCHAR': char. and the *Note `TEXT': blob. types), the
          maximum length in characters for `utf8' columns is less in
          MySQL 6.0 than previously.

        * For all character data types (*Note `CHAR': char, *Note
          `VARCHAR': char, and the *Note `TEXT': blob. types), the
          maximum number of characters for `utf8' columns that can be
          indexed is less in MySQL 6.0 than previously.

     Consequently, if you want to upgrade tables from the old `utf8'
     (now `utf8mb3') to the current `utf8', it may be necessary to
     change some column or index definitions.

     For additional details about the new Unicode character sets and
     potential incompatibilities, see *Note charset-unicode::, and
     *Note charset-unicode-upgrading::.

     If you use events, a known issue is that if you upgrade from MySQL
     5.1 to 6.0.4 though 6.0.6, the event scheduler will not work, even
     after you run *Note `mysql_upgrade': mysql-upgrade. (This is an
     issue only for an upgrade, not for a new installation of MySQL
     6.0.x.) As of MySQL 6.0.7, *Note `mysql_upgrade': mysql-upgrade.
     handles upgrading the system tables properly. If you upgrade to
     6.0.4 through 6.0.6, you can work around this upgrading problem by
     using these instructions:

       1. In MySQL 5.1, before upgrading, create a dump file containing
          your `mysql.event' table:

               shell> mysqldump -uroot -p mysql event > event.sql

       2. Stop the server, upgrade to MySQL 6.0, and start the server.

       3. Recreate the `mysql.event' table using the dump file:

               shell> mysql -uroot -p mysql < event.sql

       4. Run *Note `mysql_upgrade': mysql-upgrade. to upgrade the other
          system tables in the `mysql' database:

               shell> mysql_upgrade -uroot -p

       5. Restart the server. The event scheduler should run normally.

   * *Incompatible Change*: Because of a change in the format of the
     `Falcon' pages stored within `Falcon' database files, `Falcon'
     databases created in MySQL 6.0.4 (or later) are not compatible
     with previous releases, and existing `Falcon' databases are
     incompatible with MySQL 6.0.4 (and later versions. You should dump
     `Falcon' databases using *Note `mysqldump': mysqldump. before
     upgrading, and then reload them after the upgrade. For more
     information, see *Note mysqldump::.

   * *MySQL Cluster*: Introduced the `Ndb_execute_count'
     (http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-status-variables.html#statvar_Ndb_execute_count)
     status variable, which measures the number of round trips made by
     queries to the `NDB' kernel.

   * *Partitioning*: Error messages for partitioning syntax errors have
     been made more descriptive.  (Bug#29368
     (http://bugs.mysql.com/29368))

   * *Cluster Replication*: *Replication*: A replication heartbeat
     mechanism has been added to facilitate monitoring. This provides
     an alternative to checking log files, making it possible to detect
     in real time when a slave has failed.

     Configuration of heartbeats is done via a new
     `MASTER_HEARTBEAT_PERIOD = INTERVAL' clause for the *Note `CHANGE
     MASTER TO': change-master-to. statement (see *Note
     change-master-to::); monitoring can be done by checking the values
     of the status variables `Slave_heartbeat_period' and
     `Slave_received_heartbeats' (see *Note server-status-variables::).

     The addition of replication heartbeats addresses a number of
     issues:

        * Relay logs were rotated every `slave_net_timeout'
          (http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_net_timeout)
          seconds even if no statements were being replicated.

        * *Note `SHOW SLAVE STATUS': show-slave-status. displayed an
          incorrect value for `seconds_behind_master' following a *Note
          `FLUSH LOGS': flush. statement.

        * Replication master-slave connections used `slave_net_timeout'
          (http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#sysvar_slave_net_timeout)
          for connection timeouts.

     (Bug#20435 (http://bugs.mysql.com/20435), Bug#29309
     (http://bugs.mysql.com/29309), Bug#30932
     (http://bugs.mysql.com/30932))

   * *Replication*: Replication of the following SQL functions now
     switches to row-based logging in `MIXED' mode, and generates a
     warning in `STATEMENT' mode:

        * `USER()'

        * `CURRENT_USER()' and its alias `CURRENT_USER'

        * `FOUND_ROWS()'

        * `ROW_COUNT()'

     See *Note binary-log-mixed::, for more information.  (Bug#12092
     (http://bugs.mysql.com/12092), Bug#28086
     (http://bugs.mysql.com/28086), Bug#30244
     (http://bugs.mysql.com/30244))

   * The (undocumented) `configure' script previously included with
     binary distributions is no longer included.  (Bug#35011
     (http://bugs.mysql.com/35011))

   * The `--event-scheduler' option without a value disabled the event
     scheduler. Now it enables the event scheduler.  (Bug#31332
     (http://bugs.mysql.com/31332))

   * *Note `mysqldump': mysqldump. produces a `-- Dump completed on
     DATE' comment at the end of the dump if `--comments' is given. The
     date causes dump files for identical data take at different times
     to appear to be different. The new options `--dump-date' and
     `--skip-dump-date' control whether the date is added to the
     comment.  `--skip-dump-date' suppresses date printing. The default
     is `--dump-date' (include the date in the comment).  (Bug#31077
     (http://bugs.mysql.com/31077))

   * MySQL now can be compiled with `gcc' 4.2.x.  There was a problem
     involving a conflict with the `min()' and `max()' macros in
     `my_global.h'.  (Bug#28184 (http://bugs.mysql.com/28184))

   * Added the `--auto-vertical-output' option to *Note `mysql': mysql.
     which causes result sets to be displayed vertically if they are
     too wide for the current window, and using normal tabular format
     otherwise. (This applies to statements terminated by `;' or `\G'.)
     (Bug#26780 (http://bugs.mysql.com/26780))

   * It is now possible to set `long_query_time' in microseconds or to
     0. Setting this value to 0 causes all queries to be recorded in
     the slow query log.

     Currently, fractional values can be used only when logging to
     files. We plan to provide this functionality for logging to tables
     when time-related data types are enhanced to support microsecond
     resolution.  (Bug#25412 (http://bugs.mysql.com/25412))

   * `INFORMATION_SCHEMA' implementation changes were made that
     optimize certain types of queries for `INFORMATION_SCHEMA' tables
     so that they execute more quickly.  *Note
     information-schema-optimization::, provides guidelines on how to
     take advantage of these optimizations by writing queries that
     minimize the need for the server to access the file system to
     obtain the information contained in `INFORMATION_SCHEMA' tables.
     By writing queries that enable the server to avoid directory scans
     or opening table files, you will obtain better performance.
     (Bug#19588 (http://bugs.mysql.com/19588))

   * Three options were added to *Note `mysqldump': mysqldump. make it
     easier to generate a dump from a slave server.  `--dump-slave' is
     similar to `--master-data', but the *Note `CHANGE MASTER TO':
     change-master-to. statement contains binary log coordinates for
     the slave's master host, not the slave itself.
     `--apply-slave-statements' causes *Note `STOP SLAVE': stop-slave.
     and *Note `START SLAVE': start-slave. statements to be added
     before the *Note `CHANGE MASTER TO': change-master-to.  statement
     and at the end of the output, respectively.
     `--include-master-host-port' causes the *Note `CHANGE MASTER TO':
     change-master-to.  statement to include `MASTER_PORT' and
     `MASTER_HOST' options for the slave's master.  (Bug#8368
     (http://bugs.mysql.com/8368))

   * `mysql-test-run.pl' now supports a `--combination' option for
     specifying options to the *Note `mysqld': mysqld. server. This
     option is similar to `--mysqld' but should be given two or more
     times.  `mysql-test-run.pl' executes multiple test runs, using the
     options for each instance of `--combination' in successive runs.

     For test runs specific to a given test suite, an alternative to
     the use of `--combination' is to create a `combinations' file in
     the suite directory.  The file should contain a section of options
     for each test run.

   * An alternative thread model is available for dealing with the
     issues that occur with the original one-thread-per-client model
     when scaling to large numbers of simultaneous connections. This
     model uses thread pooling:

        * Connection manager threads do not dedicate a thread to each
          client connection. Instead, the connection is added to the
          set of existing connection sockets. The server collects input
          from these sockets and when a complete request has been
          received from a given client, it is queued for service.

        * The server maintains a pool of service threads to process
          requests. When a queued request is waiting and there is an
          available (not busy) service thread in the pool, the request
          is given to the thread to be handled. After processing the
          request, the service thread becomes available to process
          other requests.

          Service threads are created at server startup and exist until
          the server terminates. A given service thread is not tied to
          a specific client connection and the requests that it
          processes over time may originate from different client
          connections.

        * The pool of service threads has a fixed size, so the amount
          of memory required for it does not increase as the number of
          client connections increases.

     For information about choosing one thread model over the other and
     tuning the parameters that control thread resources, see *Note
     connection-threads::.

   * When the server detects `MyISAM' table corruption, it now writes
     additional information to the error log, such as the name and line
     number of the source file, and the list of threads accessing the
     table. Example: `Got an error from thread_id=1, mi_dynrec.c:368'.
     This is useful information to include in bug reports.

   * Two options relating to slow query logging have been added for
     *Note `mysqld': mysqld.  `--log-slow-slave-statements' causes slow
     statements executed by a replication slave to be written to the
     slow query log; `min_examined_row_limit' can be used to cause
     queries which examine fewer than the stated number of rows not to
     be logged.

Bugs fixed:

   * *Security Fix*: *Replication*: It was possible for any connected
     user to issue a *Note `BINLOG': binlog. statement, which could be
     used to escalate privileges.

     Use of the *Note `BINLOG': binlog. statement now requires the
     `SUPER' privilege.  (Bug#31611 (http://bugs.mysql.com/31611),
     CVE-2007-6313
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-6313))

   * *Security Fix*: Three vulnerabilities in yaSSL versions 1.7.5 and
     earlier were discovered that could lead to a server crash or
     execution of unauthorized code. The exploit requires a server with
     yaSSL enabled and TCP/IP connections enabled, but does not require
     valid MySQL account credentials. The exploit does not apply to
     OpenSSL.

     *Note*:

     The proof-of-concept exploit is freely available on the Internet.
     Everyone with a vulnerable MySQL configuration is advised to
     upgrade _immediately_.

     (Bug#33814 (http://bugs.mysql.com/33814), CVE-2008-0226
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0226),
     CVE-2008-0227
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0227))

   * *Security Fix*: Using *Note `RENAME TABLE': rename-table. against a
     table with explicit `DATA DIRECTORY' and `INDEX DIRECTORY' options
     can be used to overwrite system table information by replacing the
     symbolic link points. the file to which the symlink points.

     MySQL will now return an error when the file to which the symlink
     points already exists.  (Bug#32111 (http://bugs.mysql.com/32111),
     CVE-2007-5969
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-5969))

   * *Security Fix*: *Note `ALTER VIEW': alter-view. retained the
     original `DEFINER' value, even when altered by another user, which
     could allow that user to gain the access rights of the view. Now
     *Note `ALTER VIEW': alter-view. is allowed only to the original
     definer or users with the `SUPER' privilege.  (Bug#29908
     (http://bugs.mysql.com/29908))

   * *Security Fix*: When using a `FEDERATED' table, the local server
     could be forced to crash if the remote server returned a result
     with fewer columns than expected.  (Bug#29801
     (http://bugs.mysql.com/29801))

   * *Incompatible Change*: The `falcon_lock_timeout' system variable,
     which had a value in milliseconds, has been replaced with
     `falcon_lock_wait_timeout', which has a value in seconds. The
     default value of `falcon_lock_wait_timeout' is 50 seconds. This
     has been done for better name and unit consistency with the
     `innodb_lock_wait_timeout' system variable. Uses of the old
     variable should be converted to use the new variable.  (Bug#33474
     (http://bugs.mysql.com/33474), Bug#33072
     (http://bugs.mysql.com/33072))

   * *Incompatible Change*: With `ONLY_FULL_GROUP_BY' SQL mode enabled,
     queries such as `SELECT a FROM t1 HAVING COUNT(*)>2' were not
     being rejected as they should have been.

     This fix results in the following behavior:

        * There is a check against mixing group and non-group columns
          _only_ when `ONLY_FULL_GROUP_BY' is enabled.

        * This check is done both for the select list and for the
          `HAVING' clause if there is one.

     This behavior differs from previous versions as follows:

        * Previously, the `HAVING' clause was not checked when
          `ONLY_FULL_GROUP_BY' was enabled; now it is checked.

        * Previously, the select list was checked even when
          `ONLY_FULL_GROUP_BY' was not enabled; now it is checked only
          when `ONLY_FULL_GROUP_BY' is enabled.

     (Bug#31794 (http://bugs.mysql.com/31794))

   * *Incompatible Change*: *Note `SET PASSWORD': set-password.
     statements now cause an implicit commit, and thus are prohibited
     within stored functions and triggers.  (Bug#30904
     (http://bugs.mysql.com/30904))

   * *Incompatible Change*: The `mysql_install_db' script could fail to
     locate some components (including *Note `resolveip': resolveip.)
     during execution if the `--basedir' option was specified on the
     command-line or within the `my.cnf' file. This was due to a
     conflict when comparing the compiled-in values and the supplied
     values.

     The `--source-install' command-line option to the script has been
     removed and replaced with the `--srcdir' option.  *Note
     `mysql_install_db': mysql-install-db. now locates components
     either using the compiled-in options, the `--basedir' option or
     `--srcdir' option.  (Bug#30759 (http://bugs.mysql.com/30759))

   * *Incompatible Change*: It was possible to create a view having a
     column whose name consisted of an empty string or space characters
     only.

     One result of this bug fix is that aliases for columns in the view
     `SELECT' statement are checked to ensure that they are legal
     column names. In particular, the length must be within the maximum
     column length of 64 characters, not the maximum alias length of
     256 characters. This can cause problems for replication or loading
     dump files. For additional information and workarounds, see *Note
     view-restrictions::.  (Bug#27695 (http://bugs.mysql.com/27695))
     See also Bug#31202 (http://bugs.mysql.com/31202).

   * *Incompatible Change*: It was possible for option files to be read
     twice at program startup, if some of the standard option file
     locations turned out to be the same directory. Now duplicates are
     removed from the list of files to be read.

     Also, users could not override system-wide settings using
     `~/.my.cnf' because `SYSCONFDIR/my.cnf' was read last. The latter
     file now is read earlier so that `~/.my.cnf' can override
     system-wide settings.

     The fix for this problem had a side effect such that on Unix,
     MySQL programs looked for options in `~/my.cnf' rather than the
     standard location of `~/.my.cnf'. That problem was addressed as
     Bug#38180 (http://bugs.mysql.com/38180).  (Bug#20748
     (http://bugs.mysql.com/20748))

   * *Incompatible Change*: A number of problems existed in the
     implementation of `MERGE' tables that could cause problems. The
     problems are summarized below:

        * Bug#26379 (http://bugs.mysql.com/26379) - Combination of
          *Note `FLUSH TABLE': flush.  and *Note `REPAIR TABLE':
          repair-table. corrupts a `MERGE' table. This was caused in a
          number of situations:

            1. A thread trying to lock a `MERGE' table performs busy
               waiting while *Note `REPAIR TABLE': repair-table. or a
               similar table administration task is ongoing on one or
               more of its MyISAM tables.

            2. A thread trying to lock a `MERGE' table performs busy
               waiting until all threads that did *Note `REPAIR TABLE':
               repair-table. or similar table administration tasks on
               one or more of its MyISAM tables in LOCK TABLES segments
               do UNLOCK TABLES. The difference against problem #1 is
               that the busy waiting takes place after the
               administration task. It is terminated by *Note `UNLOCK
               TABLES': lock-tables. only.

            3. Two *Note `FLUSH TABLES': flush. within a *Note `LOCK
               TABLES': lock-tables. segment can invalidate the lock.
               This does not require a `MERGE' table. The first *Note
               `FLUSH TABLES': flush. can be replaced by any statement
               that requires other threads to reopen the table. In 5.0
               and 5.1 a single *Note `FLUSH TABLES': flush. can
               provoke the problem.

        * Bug#26867 (http://bugs.mysql.com/26867) - Simultaneously
          executing *Note `LOCK TABLES': lock-tables. and *Note `REPAIR
          TABLE': repair-table. on a `MERGE' table would result in
          memory/cpu hogging.

          Trying DML on a `MERGE' table, which has a child locked and
          repaired by another thread, made an infinite loop in the
          server.

        * Bug#26377 (http://bugs.mysql.com/26377) - Deadlock with
          `MERGE' and *Note `FLUSH TABLE': flush.

          Locking a MERGE table and its children in parent-child order
          and flushing the child deadlocked the server.

        * Bug#25038 (http://bugs.mysql.com/25038) - Waiting *Note
          `TRUNCATE': truncate.

          Truncating a MERGE child, while the MERGE table was in use,
          let the truncate fail instead of waiting for the table to
          become free.

        * Bug#25700 (http://bugs.mysql.com/25700) - `MERGE' base tables
          get corrupted by `OPTIMIZE/ANALYZE/REPAIR TABLE'

          Repairing a child of an open `MERGE' table corrupted the
          child. It was necessary to *Note `FLUSH': flush. the child
          first.

        * Bug#30275 (http://bugs.mysql.com/30275) - `MERGE' tables:
          *Note `FLUSH TABLES': flush. or *Note `UNLOCK TABLES':
          lock-tables. causes server to crash.

          Flushing and optimizing locked `MERGE' children crashed the
          server.

        * Bug#19627 (http://bugs.mysql.com/19627) - temporary merge
          table locking

          Use of a temporary `MERGE' table with non-temporary children
          could corrupt the children.

          Temporary tables are never locked. Creation of tables with
          non-temporary children of a temporary `MERGE' table is now
          prohibited.

        * Bug#27660 (http://bugs.mysql.com/27660) - `Falcon': `MERGE'
          table possible

          It was possible to create a `MERGE' table with non-`MyISAM'
          children.

        * Bug#30273 (http://bugs.mysql.com/30273) - `MERGE' tables:
          Can't lock file (errno: 155)

          This was a Windows-only bug. Table administration statements
          sometimes failed with "Can't lock file (errno: 155)".

     The fix introduces the following changes in behavior:

        * This patch changes the behavior of temporary `MERGE' tables.
          Temporary `MERGE' must have temporary children. The old
          behavior was wrong. A temporary table is not locked.  Hence
          even non-temporary children were not locked. See Bug#19627
          (http://bugs.mysql.com/19627).

        * You cannot change the union list of a non-temporary `MERGE'
          table when LOCK TABLES is in effect. The following does _not_
          work:

               CREATE TABLE m1 ... ENGINE=MRG_MYISAM ...;
               LOCK TABLES t1 WRITE, t2 WRITE, m1 WRITE;
               ALTER TABLE m1 ... UNION=(t1,t2) ...;

          However, you can do this with a temporary `MERGE' table.

        * You cannot create a `MERGE' table with `CREATE ... SELECT',
          neither as a temporary `MERGE' table, nor as a non-temporary
          `MERGE' table. For example, `CREATE TABLE m1 ...
          ENGINE=MRG_MYISAM ... SELECT ...;' causes the error message:
          `table is not BASE TABLE'.

     (Bug#19627 (http://bugs.mysql.com/19627), Bug#25038
     (http://bugs.mysql.com/25038), Bug#25700
     (http://bugs.mysql.com/25700), Bug#26377
     (http://bugs.mysql.com/26377), Bug#26379
     (http://bugs.mysql.com/26379), Bug#26867
     (http://bugs.mysql.com/26867), Bug#27660
     (http://bugs.mysql.com/27660), Bug#30275
     (http://bugs.mysql.com/30275), Bug#30491
     (http://bugs.mysql.com/30491))

   * *Partitioning*: *Important Note*: An apostrophe or single quote
     character (`'') used in the `DATA DIRECTORY', `INDEX DIRECTORY', or
     `COMMENT' for a `PARTITION' clause caused the server to crash.
     When used as part of a *Note `CREATE TABLE': create-table.
     statement, the crash was immediate. When used in an *Note `ALTER
     TABLE': alter-table. statement, the crash did not occur until
     trying to perform a *Note `SELECT': select. or DML statement on
     the table. In either case, the server could not be completely
     restarted until the `.FRM' file corresponding to the newly created
     or altered table was deleted.

     *Note*:

     Upgrading to the current (or later) release solves this problem
     only for tables that are newly created or altered.  Tables created
     or altered in previous versions of the server to include `''
     characters in `PARTITION' options must still be removed by
     deleting the corresponding `.FRM' files and re-creating them
     afterwards.

     (Bug#30695 (http://bugs.mysql.com/30695))

   * *Partitioning*: *MySQL Cluster*: `EXPLAIN PARTITIONS' reported
     partition usage by queries on `NDB' tables according to the
     standard MySQL hash function than the hash function used in the
     `NDB' storage engine.  (Bug#29550 (http://bugs.mysql.com/29550))

   * *Replication*: *MySQL Cluster*: Row-based replication from or to a
     big-endian machine where the table used the `NDB' storage engine
     failed, if the same table on the other machine was either
     non-`NDB' or the other machine was little-endian.  (Bug#29549
     (http://bugs.mysql.com/29549), Bug#30790
     (http://bugs.mysql.com/30790)) See also Bug#24231
     (http://bugs.mysql.com/24231), Bug#30024
     (http://bugs.mysql.com/30024), Bug#30133
     (http://bugs.mysql.com/30133), Bug#30134
     (http://bugs.mysql.com/30134).

   * *MySQL Cluster*: *Replication*: (Replication): Inconsistencies
     could occur between the master and the slave when replicating Disk
     Data tables.  (Bug#19259 (http://bugs.mysql.com/19259), Bug#19227
     (http://bugs.mysql.com/19227))

   * *MySQL Cluster*: An insert or update with combined range and
     equality constraints failed when run against an `NDB' table with
     the error `Got unknown error from NDB'. An example of such a
     statement would be `UPDATE t1 SET b = 5 WHERE a IN (7,8) OR a >=
     10;'.  (Bug#31874 (http://bugs.mysql.com/31874))

   * *MySQL Cluster*: An error with an `if' statement in
     `sql/ha_ndbcluster.cc' could potentially lead to an infinite loop
     in case of failure when working with `AUTO_INCREMENT' columns in
     `NDB' tables.  (Bug#31810 (http://bugs.mysql.com/31810))

   * *MySQL Cluster*: The `NDB' storage engine code was not safe for
     strict-alias optimization in `gcc' 4.2.1.  (Bug#31761
     (http://bugs.mysql.com/31761))

   * *MySQL Cluster*: Following an upgrade, `ndb_mgmd' would fail with
     an ArbitrationError.  (Bug#31690 (http://bugs.mysql.com/31690))

   * *MySQL Cluster*: It was possible in some cases for a node group to
     be `lost' due to missed local checkpoints following a system
     restart.  (Bug#31525 (http://bugs.mysql.com/31525))

   * *MySQL Cluster*: A query against a table with *Note `TEXT': blob.
     or *Note `BLOB': blob. columns that would return more than a
     certain amount of data failed with `Got error 4350 'Transaction
     already aborted' from NDBCLUSTER'.  (Bug#31482
     (http://bugs.mysql.com/31482)) This regression was introduced by
     Bug#29102 (http://bugs.mysql.com/29102).

   * *MySQL Cluster*: `NDB' tables having names containing
     non-alphanumeric characters (such as ` `$' ') were not discovered
     correctly.  (Bug#31470 (http://bugs.mysql.com/31470))

   * *MySQL Cluster*: A node failure during a local checkpoint could
     lead to a subsequent failure of the cluster during a system
     restart.  (Bug#31257 (http://bugs.mysql.com/31257))

   * *MySQL Cluster*: A cluster restart could sometimes fail due to an
     issue with table IDs.  (Bug#30975 (http://bugs.mysql.com/30975))

   * *MySQL Cluster*: In some cases, the cluster managment server
     logged entries multiple times following a restart of `mgmd'.
     (Bug#29565 (http://bugs.mysql.com/29565))

   * *MySQL Cluster*: `ndb_mgm' `--help' did not display any
     information about the `-a' option.  (Bug#29509
     (http://bugs.mysql.com/29509))

   * *MySQL Cluster*: An interpreted program of sufficient size and
     complexity could cause all cluster data nodes to shut down due to
     buffer overruns.  (Bug#29390 (http://bugs.mysql.com/29390))

   * *MySQL Cluster*: Performing *Note `DELETE': delete. operations
     after a data node had been shut down could lead to inconsistent
     data following a restart of the node.  (Bug#26450
     (http://bugs.mysql.com/26450))

   * *MySQL Cluster*: `UPDATE IGNORE' could sometimes fail on `NDB'
     tables due to the use of unitialized data when checking for
     duplicate keys to be ignored.  (Bug#25817
     (http://bugs.mysql.com/25817))

   * *MySQL Cluster*: The cluster log was formatted inconsistently and
     contained extraneous newline characters.  (Bug#25064
     (http://bugs.mysql.com/25064))

   * *Partitioning*: An *Note `INSERT': insert. into a `Falcon' table
     with partitions and an auto-increment column would fail.
     (Bug#33661 (http://bugs.mysql.com/33661))

   * *Partitioning*: Multiple simultaneous inserts into a partitioned
     `Falcon' table could deadlock.  (Bug#33480
     (http://bugs.mysql.com/33480), Bug#33735
     (http://bugs.mysql.com/33735))

   * *Partitioning*: Repeated updates of a table that was partitioned by
     `KEY' on a *Note `TIMESTAMP': datetime. column eventually crashed
     the server.  (Bug#32067 (http://bugs.mysql.com/32067))

   * *Partitioning*: Selecting from a table partitioned by `KEY' on a
     *Note `VARCHAR': char. column whose size was greater than 65530
     caused the server to crash.  (Bug#31705
     (http://bugs.mysql.com/31705))

   * *Partitioning*: *Note `INSERT DELAYED': insert-delayed. on a
     partitioned table crashed the server. The server now rejects the
     statement with an error.  (Bug#31210 (http://bugs.mysql.com/31210))

   * *Partitioning*: Using *Note `ALTER TABLE': alter-table. to
     partition an existing table having an `AUTO_INCREMENT' column
     could crash the server.  (Bug#30878 (http://bugs.mysql.com/30878))
     This regression was introduced by Bug#27405
     (http://bugs.mysql.com/27405).

   * *Partitioning*: `Falcon' cannot drop a table for which there is a
     pending transaction, but the error message for such attempts was
     misleading.  (Bug#22972 (http://bugs.mysql.com/22972))

   * *Cluster Replication*: *Replication*: A node failure during
     replication could lead to buckets out of order; now active
     subscribers are checked for, rather than empty buckets.
     (Bug#31701 (http://bugs.mysql.com/31701))

   * *Replication*: When using a transactional storage engine not using
     statement-based logging, a duplicate key error on the master
     caused replication to fail. This issue was first observed when
     using the `Falcon' storage engine.  (Bug#33688
     (http://bugs.mysql.com/33688))

   * *Replication*: When updating columns for a row when using a
     `Falcon' table, the values for columns that were not updated were
     replicated as `NULL'.  (Bug#33055 (http://bugs.mysql.com/33055))

   * *Replication*: When dropping a database containing a stored
     procedure while using row-cased replication, the delete of the
     stored procedure from the `mysql.proc' table was recorded in the
     binary log following the *Note `DROP DATABASE': drop-database.
     statement. To correct this issue, *Note `DROP DATABASE':
     drop-database. now uses statement-based replication.  (Bug#32435
     (http://bugs.mysql.com/32435))

   * *Replication*: `DELETE FROM TBL_NAME' (no `WHERE' clause) for a
     `Falcon' table caused replication to fail on the slave.
     (Bug#32150 (http://bugs.mysql.com/32150))

   * *Replication*: It was possible for the name of the relay log file
     to exceed the amount of memory reserved for it, possibly leading
     to a crash of the server.  (Bug#31836
     (http://bugs.mysql.com/31836)) See also Bug#28597
     (http://bugs.mysql.com/28597).

   * *Replication*: Corruption of log events caused the server to crash
     on 64-bit Linux systems having 4 GB of memory or more.  (Bug#31793
     (http://bugs.mysql.com/31793))

   * *Replication*: Trying to replicate an update of a row that was
     missing on the slave led to a failure on the slave.  (Bug#31702
     (http://bugs.mysql.com/31702))

   * *Replication*: `Falcon' tables would fail during replication if
     ROW-based replication was specified.  (Bug#31671
     (http://bugs.mysql.com/31671))

   * *Replication*: Table names were displayed as binary `garbage'
     characters in slave error messages. The issue was observed on
     64-bit Windows but may have effected other platforms.  (Bug#30854
     (http://bugs.mysql.com/30854))

   * *Replication*: One thread could read uninitialized memory from the
     stack of another thread. This issue was only known to occur in a
     *Note `mysqld': mysqld. process acting as both a master and a
     slave.  (Bug#30752 (http://bugs.mysql.com/30752))

   * *Replication*: A new configuration option, `falcon_support_xa' has
     been added. The option specifies whether `Falcon' should report
     itself as a two-phase commit storage engine, and therefore take
     part in XA transactions.  (Bug#29371 (http://bugs.mysql.com/29371))

   * *Replication*: It was possible to set `SQL_SLAVE_SKIP_COUNTER'
     such that the slave would jump into the middle of an event group,
     including possibly a transaction.  (Bug#28618
     (http://bugs.mysql.com/28618)) See also Bug#12691
     (http://bugs.mysql.com/12691).

   * *Replication*: Due a previous change in how the default name and
     location of the binary log file were determined, replication failed
     following some upgrades.  (Bug#28597
     (http://bugs.mysql.com/28597), Bug#28603
     (http://bugs.mysql.com/28603)) See also Bug#31836
     (http://bugs.mysql.com/31836).

     This regression was introduced by Bug#20166
     (http://bugs.mysql.com/20166).

   * *Replication*: Connections from one *Note `mysqld': mysqld. server
     to another failed on Mac OS X, affecting replication and
     `FEDERATED' tables.  (Bug#26664 (http://bugs.mysql.com/26664)) See
     also Bug#29083 (http://bugs.mysql.com/29083).

   * *Replication*: Stored procedures having *Note `BIT': numeric-types.
     parameters were not replicated correctly.  (Bug#26199
     (http://bugs.mysql.com/26199))

   * *Replication*: Issuing *Note `SHOW SLAVE STATUS':
     show-slave-status. as *Note `mysqld': mysqld. was shutting down
     could cause a crash.  (Bug#26000 (http://bugs.mysql.com/26000))

   * *Replication*: If a temporary error occured inside an event group
     on an event that was not the first event of the group, the slave
     could get caught in an endless loop because the retry counter was
     reset whenever an event was executed successfully.  (Bug#24860
     (http://bugs.mysql.com/24860)) See also Bug#12691
     (http://bugs.mysql.com/12691), Bug#23171
     (http://bugs.mysql.com/23171).

   * *Replication*: An *Note `UPDATE': update. statement using a stored
     function that modified a non-transactional table was not logged if
     it failed. This caused the copy of the non-transactional table on
     the master have a row that the copy on the slave did not.

     In addition, when an `INSERT ... ON DUPLICATE KEY UPDATE'
     statement encountered a duplicate key constraint, but the *Note
     `UPDATE': update. did not actually change any data, the statement
     was not logged. As a result of this fix, such statements are now
     treated the same for logging purposes as other *Note `UPDATE':
     update.  statements, and so are written to the binary log.
     (Bug#23333 (http://bugs.mysql.com/23333)) See also Bug#12713
     (http://bugs.mysql.com/12713).

   * *Replication*: A replication slave sometimes failed to reconnect
     because it was unable to run *Note `SHOW SLAVE HOSTS':
     show-slave-hosts.  It was not necessary to run this statement on
     slaves (since the master should track connection IDs), and the
     execution of this statement by slaves was removed.  (Bug#21132
     (http://bugs.mysql.com/21132)) See also Bug#13963
     (http://bugs.mysql.com/13963), Bug#21869
     (http://bugs.mysql.com/21869).

   * *Replication*: A replication slave sometimes stopped for changes
     that were idempotent (that is, such changes should have been
     considered `safe'), even though it should have simply noted that
     the change was already done, and continued operation.  (Bug#19958
     (http://bugs.mysql.com/19958))

   * *Cluster Replication*: A replication slave could return `garbage'
     data that was not in recognizable row format due to a problem with
     the internal `all_set()' method.  (Bug#33375
     (http://bugs.mysql.com/33375))

   * *Cluster Replication*: Replicating `NDB' tables with extra *Note
     `VARCHAR': char. columns on the master caused the slave to fail.
     (Bug#31646 (http://bugs.mysql.com/31646)) See also Bug#29549
     (http://bugs.mysql.com/29549).

   * *Cluster Replication*: In some cases, not all tables were properly
     initialized before the binary log thread was started.  (Bug#31618
     (http://bugs.mysql.com/31618))

   * *Cluster API*: A buffer overrun in `NdbBlob::setValue()' caused
     erroneous results on Mac OS X.  (Bug#31284
     (http://bugs.mysql.com/31284))

   * Setting `falcon_consistent_read' to a value of 1 or `ON' resulted
     in a value of -1 being assigned.  (Bug#34331
     (http://bugs.mysql.com/34331))

   * Compiling MySQL on FreeBSD would fail due to missing definitions
     for certain network constants.  (Bug#34292
     (http://bugs.mysql.com/34292))

   * The `INFORMATION_SCHEMA.FALCON_TRANSACTIONS' had two columns named
     `STATE'.  (Bug#34241 (http://bugs.mysql.com/34241))

   * For `Falcon', under some circumstances, a rolled back record could
     appear not to be removed.  (Bug#34174
     (http://bugs.mysql.com/34174))

   * Attempting to set the isolation level to a value not supported by
     `Falcon' caused a `Falcon' assertion failure.  (Bug#34164
     (http://bugs.mysql.com/34164))

   * `Falcon' did not compile on Mac OS X/Intel or Mac OS X/PPC.
     (Bug#34095 (http://bugs.mysql.com/34095))

   * When inserting very large data sets into table using `INSERT INTO
     ... SELECT FROM' on a `Falcon' table when the value of
     `falcon_page_cache_size' is higher than the available memory.
     Instead of returning an error, *Note `mysqld': mysqld. would crash
     in this instance.  (Bug#34086 (http://bugs.mysql.com/34086))

   * For `Falcon', an initializing transaction created a dependency on
     a commitNoUpdate transaction releasing transaction dependencies,
     which caused an assertion failure.  (Bug#33759
     (http://bugs.mysql.com/33759))

   * The output from *Note `SHOW CREATE TABLE': show-create-table.  on
     a `Falcon' table would not include the `AUTO_INCREMENT' value
     parameters.  (Bug#33662 (http://bugs.mysql.com/33662))

   * For table creation, `Falcon' did not handle identifiers with
     embedded double quotes.  (Bug#33657 (http://bugs.mysql.com/33657),
     Bug#33667 (http://bugs.mysql.com/33667))

   * Contention between concurrent `Falcon' transactions could cause
     some queries to be starved for a long time.  (Bug#33634
     (http://bugs.mysql.com/33634))

   * Incomplete `Falcon' recovery after server restarts eventually
     resulted in tablespace corruption.  (Bug#33608
     (http://bugs.mysql.com/33608), Bug#33665
     (http://bugs.mysql.com/33665))

   * Using `falcon_debug_mask' to enable debugging messages could lead
     to some messages not being correctly flushed to the log file.
     (Bug#33531 (http://bugs.mysql.com/33531))

   * Table recovery failed repeatedly after starting the server with a
     corrupted `Falcon' tablespace, causing the server to crash.
     (Bug#33517 (http://bugs.mysql.com/33517))

   * After a server restart, `Falcon' mishandled metadata, resulting in
     apparent corruption of *Note `BLOB': blob. data.  (Bug#33492
     (http://bugs.mysql.com/33492))

   * Dropping a tablespace for the `Falcon' storage engine when the
     specified tablespace did not exist would silently succeed, instead
     of generating a suitable error message.  (Bug#33212
     (http://bugs.mysql.com/33212))

   * Multiple concurrent delete operations on a `Falcon' table were
     serialized rather than executing concurrently, resulting in poor
     performance.  (Bug#33191 (http://bugs.mysql.com/33191))

   * Inserting millions of rows into a `Falcon' table could cause the
     insert operation to hang.  (Bug#33175
     (http://bugs.mysql.com/33175))

   * The columns in the `INFORMATION_SCHEMA' table for
     `FALCON_SERIAL_LOG_INFO', `FALCON_TRANSACTIONS', and
     `FALCON_TRANSACTION_SUMMARY' contained a reference to the databae
     of tablespace, but the column information was actually showing
     instances of the `Falcon' engine. The tables have been updated to
     a different structure.  (Bug#33141 (http://bugs.mysql.com/33141))

   * Using *Note `ALTER TABLE': alter-table. to convert a *Note `CHAR':
     char. column using the `ucs2' character set to *Note `VARBINARY':
     binary-varbinary. when using a `Falcon' table would cause a crash.
     (Bug#33081 (http://bugs.mysql.com/33081))

   * Multiple `Falcon' gopher threads attempting to update the same
     index could result in failure to add new index entries.
     (Bug#33080 (http://bugs.mysql.com/33080))

   * `Falcon' tried to delete a record from an empty record locator
     page, which could cause a server crash.  (Bug#33068
     (http://bugs.mysql.com/33068))

   * `Falcon' failed to rebuild a Section page during recovery, causing
     a server crash.  (Bug#32921 (http://bugs.mysql.com/32921))

   * Using `Falcon' when accessing multiple versions of the same
     record, certain records could fail to be retrieved from the record
     cache, causing an assertion failure.  (Bug#32862
     (http://bugs.mysql.com/32862))

   * Creating an index on a `Falcon' table with a column using UTF32
     that has been converted to UTF8 would cause a server crash.
     (Bug#32833 (http://bugs.mysql.com/32833))

   * Using *Note `ALTER TABLE': alter-table. on a `Falcon' table it
     would be possible to create two tables with the same name but
     different case.  (Bug#32830 (http://bugs.mysql.com/32830))

   * Converting a table from `InnoDB' to `Falcon', where the `Falcon'
     table with the same name (but different case) would cause a server
     crash.  (Bug#32829 (http://bugs.mysql.com/32829))

   * Concurrent *Note `TRUNCATE TABLE': truncate. operations for
     `Falcon' tables caused `Falcon' to crash.  (Bug#32730
     (http://bugs.mysql.com/32730))

   * *Note `mysqld_safe': mysqld-safe. looked for error messages in the
     wrong location.  (Bug#32679 (http://bugs.mysql.com/32679))

   * An issue with the `NO_ENGINE_SUBSTITUTION' `sql_mode' database can
     cause the creation of stored routines to fail. If you are having
     problems with creating stored routines while using this `sql_mode'
     value, remove this value from your `sql_mode' setting.  (Bug#32633
     (http://bugs.mysql.com/32633))

   * Repeatedly creating and dropping `Falcon' tablespaces failed
     because the old tablespace was not dropped before the new
     tablespace file was created.  (Bug#32621
     (http://bugs.mysql.com/32621))

   * `Falcon' did not properly handle quoted column name or tablespace
     name identifiers.  (Bug#32620 (http://bugs.mysql.com/32620))

   * The `INTERVAL()' function incorrectly handled `NULL' values in the
     value list.  (Bug#32560 (http://bugs.mysql.com/32560))

   * Use of a `NULL'-returning `GROUP BY' expression in conjunction
     with `WITH ROLLUP' could cause a server crash.  (Bug#32558
     (http://bugs.mysql.com/32558)) See also Bug#31095
     (http://bugs.mysql.com/31095).

   * `ORDER BY UpdateXML(...)' caused the server to crash in queries
     where `UpdateXML()' returned `NULL'.  (Bug#32557
     (http://bugs.mysql.com/32557))

   * `Falcon' used a fixed index key size which was too small to cope
     with some `Falcon' page sizes, leading to a crash. `Falcon' now
     supports variable-length index keys according to the supported
     page sizes. See `falcon_page_size'.  (Bug#32554
     (http://bugs.mysql.com/32554))

   * The rules for valid column names were being applied differently
     for base tables and views.  (Bug#32496
     (http://bugs.mysql.com/32496))

   * `Falcon' options to set the limits of memory usage would not be
     honored. This could lead to crashes and assertions during normal
     usage, instead of generating a suitable warning.  (Bug#32413
     (http://bugs.mysql.com/32413))

   * `Falcon' would incorrectly return the supported repeatable-read
     level when queried by the Online Backup system, preventing the
     ability to create a consistent snapshot backup.  (Bug#32301
     (http://bugs.mysql.com/32301))

   * Some uses of user variables in a query could result in a server
     crash.  (Bug#32260 (http://bugs.mysql.com/32260))

   * Under certain conditions, the presence of a `GROUP BY' clause
     could cause an `ORDER BY' clause to be ignored.  (Bug#32202
     (http://bugs.mysql.com/32202))

   * On Mac OS X, creating a `Falcon' table using a new `Falcon'
     installation caused a crash.  (Bug#32201
     (http://bugs.mysql.com/32201))

   * Altering a `Falcon' table to support an auto increment column on a
     column with existing data and null values would incorrectly update
     the table and return an incorrect count of the altered rows.
     (Bug#32194 (http://bugs.mysql.com/32194))

   * `InnoDB' does not support `SPATIAL' indexes, but could crash when
     asked to handle one. Now an error is returned.  (Bug#32125
     (http://bugs.mysql.com/32125))

   * The server crashed on optimizations involving a join of *Note
     `INT': numeric-types. and *Note `MEDIUMINT': numeric-types.
     columns and a system variable in the `WHERE' clause.  (Bug#32103
     (http://bugs.mysql.com/32103))

   * `mysql-test-run.pl' used the `--user' option when starting *Note
     `mysqld': mysqld, which produces warnings if the current user is
     not `root'. Now `--user' is added only for `root'.  (Bug#32078
     (http://bugs.mysql.com/32078))

   * Inserting, updating and deleting a large number of *Note `BLOB':
     blob. records in a `Falcon' table would take significant amount of
     time and may prevent shutdown.  (Bug#32062
     (http://bugs.mysql.com/32062))

   * On 64-bit platforms, assignments of values to enumeration-valued
     storage engine-specific system variables were not validated and
     could result in unexpected values.  (Bug#32034
     (http://bugs.mysql.com/32034))

   * A *Note `DELETE': delete. statement with a subquery in the `WHERE'
     clause would sometimes ignore an error during subquery evaluation
     and proceed with the delete operation.  (Bug#32030
     (http://bugs.mysql.com/32030))

   * Using dates in the range `'0000-00-01'' to `'0000-00-99'' range in
     the `WHERE' clause could result in an incorrect result set. (These
     dates are not in the supported range for *Note `DATE': datetime,
     but different results for a given query could occur depending on
     position of records containing the dates within a table.)
     (Bug#32021 (http://bugs.mysql.com/32021))

   * User-defined functions are not loaded if the server is started
     with the `--skip-grant-tables' option, but the server did not
     properly handle this case and issued an `Out of memory' error
     message instead.  (Bug#32020 (http://bugs.mysql.com/32020))

   * If a user-defined function was used in a *Note `SELECT': select.
     statement, and an error occurred during UDF initialization, the
     error did not terminate execution of the *Note `SELECT': select,
     but rather was converted to a warning.  (Bug#32007
     (http://bugs.mysql.com/32007))

   * In debug builds, testing the result of an `IN' subquery against
     `NULL' caused an assertion failure.  (Bug#31884
     (http://bugs.mysql.com/31884))

   * *Note `SHOW CREATE TRIGGER': show-create-trigger. caused a server
     crash.  (Bug#31866 (http://bugs.mysql.com/31866))

   * The server crashed after insertion of a negative value into an
     `AUTO_INCREMENT' column of an `InnoDB' table.  (Bug#31860
     (http://bugs.mysql.com/31860))

   * For `libmysqld' applications, handling of *Note
     `mysql_change_user()': mysql-change-user. calls left some pointers
     improperly updated, leading to server crashes.  (Bug#31850
     (http://bugs.mysql.com/31850))

   * Comparison results for `BETWEEN' were different from those for
     operators like `<' and `>' for *Note `DATETIME': datetime.-like
     values with trailing extra characters such as `'2007-10-01 00:00:00
     GMT-6''. `BETWEEN' treated the values as *Note `DATETIME':
     datetime, whereas the other operators performed a binary-string
     comparison. Now they all uniformly use a *Note `DATETIME':
     datetime.  comparison, but generate warnings for values with
     trailing garbage.  (Bug#31800 (http://bugs.mysql.com/31800))

   * The server could crash during `filesort' for `ORDER BY' based on
     expressions with `INET_NTOA()' or `OCT()' if those functions
     returned `NULL'.  (Bug#31758 (http://bugs.mysql.com/31758))

   * For a fatal error during a filesort in `find_all_keys()', the
     error was returned without the necessary handler uninitialization,
     causing an assertion failure.  (Bug#31742
     (http://bugs.mysql.com/31742))

   * The examined-rows count was not incremented for `const' queries.
     (Bug#31700 (http://bugs.mysql.com/31700))

   * The *Note `mysql_change_user()': mysql-change-user. C API function
     was subject to buffer overflow.  (Bug#31669
     (http://bugs.mysql.com/31669))

   * For *Note `SELECT ... INTO OUTFILE': select, if the `ENCLOSED BY'
     string is empty and the `FIELDS TERMINATED BY' string started with
     a special character (one of `n', `t', `r', `b', `0', `Z', or `N'),
     every occurrence of the character within field values would be
     duplicated.  (Bug#31663 (http://bugs.mysql.com/31663))

   * *Note `SHOW COLUMNS': show-columns. and *Note `DESCRIBE':
     describe. displayed `null' as the column type for a view with no
     valid definer. This caused *Note `mysqldump': mysqldump. to
     produce a non-reloadable dump file for the view.  (Bug#31662
     (http://bugs.mysql.com/31662))

   * The *Note `mysqlbug': mysqlbug. script did not include the correct
     values of `CFLAGS' and `CXXFLAGS' that were used to configure the
     distribution.  (Bug#31644 (http://bugs.mysql.com/31644))

   * For queries for which loose index scan is applicable, the
     optimizer could choose the wrong execution plan for correlated
     subqueries.  (Bug#31639 (http://bugs.mysql.com/31639))

   * Queries that include a comparison of an `INFORMATION_SCHEMA' table
     column to `NULL' caused a server crash.  (Bug#31633
     (http://bugs.mysql.com/31633))

   * `EXPLAIN EXTENDED' for *Note `SELECT': select. from
     `INFORMATION_SCHEMA' tables caused an assertion failure.
     (Bug#31630 (http://bugs.mysql.com/31630))

   * A buffer used when setting variables was not dimensioned to
     accommodate the trailing `'\0'' byte, so a single-byte buffer
     overrun was possible.  (Bug#31588 (http://bugs.mysql.com/31588))

   * For semi-join processing, pullout of functionally dependent tables
     was not handled transitively.  (Bug#31563
     (http://bugs.mysql.com/31563))

   * `HAVING' could treat lettercase of table aliases incorrectly if
     `lower_case_table_names' was enabled.  (Bug#31562
     (http://bugs.mysql.com/31562))

   * Spurious duplicate-key errors could occur for multiple-row inserts
     into an `InnoDB' table that activate a trigger.  (Bug#31540
     (http://bugs.mysql.com/31540))

   * When inserting dates into a *Note `DATETIME': datetime. column
     with a `Falcon', the values would automatically be converted with
     values between 70 and 99 converted to 1970-1999, and values from
     00 to 69 converted to 2000 to 2069. These dates are now correctly
     handled.  (Bug#31490 (http://bugs.mysql.com/31490))

   * The length of the result from `IFNULL()' could be calculated
     incorrectly because the sign of the result was not taken into
     account.  (Bug#31471 (http://bugs.mysql.com/31471))

   * Queries that used the `ref' access method or index-based subquery
     execution over indexes that have *Note `DECIMAL': numeric-types.
     columns could fail with an error `Column COL_NAME cannot be null'.
     (Bug#31450 (http://bugs.mysql.com/31450))

   * `InnoDB' now tracks locking and use of tables by MySQL only after
     a table has been successfully locked on behalf of a transaction.
     Previously, the locked flag was set and the table in-use counter
     was updated before checking whether the lock on the table
     succeeded. A subsequent failure in obtaining a lock on the table
     led to an inconsistent state as the table was neither locked nor
     in use.  (Bug#31444 (http://bugs.mysql.com/31444))

   * `SELECT 1 REGEX NULL' caused an assertion failure for debug
     servers.  (Bug#31440 (http://bugs.mysql.com/31440))

   * *Note `INFORMATION_SCHEMA.TABLES': tables-table. was returning
     incorrect information.  (Bug#31381 (http://bugs.mysql.com/31381))

   * *Note `DROP USER': drop-user. caused an increase in memory usage.
     (Bug#31347 (http://bugs.mysql.com/31347))

   * *Note `mysql_install_db': mysql-install-db. failed if the default
     storage engine was `NDB'. Now it explicitly uses `MyISAM' as the
     storage engine when running *Note `mysqld --bootstrap': mysqld.
     (Bug#31315 (http://bugs.mysql.com/31315))

   * `TABLESPACE' names within `Falcon' did not support characters
     outside the alpha-numeric ASCII character set.  (Bug#31311
     (http://bugs.mysql.com/31311))

   * For `InnoDB' tables with `READ COMMITTED' isolation level,
     semi-consistent reads used for *Note `UPDATE': update. statements
     skipped rows locked by another transaction, rather than waiting
     for the locks to be released. Consequently, rows that possibly
     should have been updated were never examined.  (Bug#31310
     (http://bugs.mysql.com/31310))

   * For an almost-full `MyISAM' table, an insert that failed could
     leave the table in a corrupt state.  (Bug#31305
     (http://bugs.mysql.com/31305))

   * When dropping Falcon tablespaces the associated tablespace file
     was not deleted.  (Bug#31296 (http://bugs.mysql.com/31296))

   * `Falcon' could crash when the maximum record size was exceeded.
     (Bug#31286 (http://bugs.mysql.com/31286))

   * *Note `myisamchk --unpack': myisamchk. could corrupt a table that
     when unpacked has static (fixed-length) row format.  (Bug#31277
     (http://bugs.mysql.com/31277))

   * Building a 64-bit binary with support for the `Falcon' storage
     engine using `gcc' on Solaris could fail. See *Note
     installing-source::, for more information.  (Bug#31268
     (http://bugs.mysql.com/31268), Bug#33126
     (http://bugs.mysql.com/33126))

   * When a *Note `TIMESTAMP': datetime. with a non-zero time part was
     converted to a *Note `DATE': datetime.  value, no warning was
     generated. This caused index lookups to assume that this is a
     valid conversion and was returning rows that match a comparison
     between a *Note `TIMESTAMP': datetime. value and a *Note `DATE':
     datetime. keypart. Now a warning is generated so that *Note
     `TIMESTAMP': datetime. with a non-zero time part will not match
     *Note `DATE': datetime. values.  (Bug#31221
     (http://bugs.mysql.com/31221))

   * If `MAKETIME()' returned `NULL' when used in an `ORDER BY' that
     was evaluated using `filesort', a server crash could result.
     (Bug#31160 (http://bugs.mysql.com/31160))

   * `LAST_INSERT_ID()' execution could be handled improperly in
     subqueries.  (Bug#31157 (http://bugs.mysql.com/31157))

   * An assertion designed to detect a bug in the `ROLLUP'
     implementation would incorrectly be triggered when used in a
     subquery context with non-cacheable statements.  (Bug#31156
     (http://bugs.mysql.com/31156))

   * When creating a `TABLESPACE' that uses the same name as an
     existing `TABLESPACE', Falcon returned `Unknown error -103'. MySQL
     now returns an error stating that the specified tablespace already
     exists.  (Bug#31114 (http://bugs.mysql.com/31114))

   * *Note `mysqldump': mysqldump. failed to handle databases
     containing a ``-'' character in the name.  (Bug#31113
     (http://bugs.mysql.com/31113))

   * Starting the server using `--read-only' and with the Event
     Scheduler enabled caused it to crash.

     *Note*:

     This issue occurred only when the server had been built with
     certain nonstandard combinations of `configure' options.

     (Bug#31111 (http://bugs.mysql.com/31111))

   * Dropping a tablespace and specifying an engine type that does not
     support tablespaces reported a warning. The response has now been
     updated to report an error.  (Bug#31110
     (http://bugs.mysql.com/31110))

   * `GROUP BY NULL WITH ROLLUP' could cause a server crash.
     (Bug#31095 (http://bugs.mysql.com/31095)) See also Bug#32558
     (http://bugs.mysql.com/32558).

   * A rule to prefer `filesort' over an indexed `ORDER BY' when
     accessing all rows of a table was being used even if a `LIMIT'
     clause was present.  (Bug#31094 (http://bugs.mysql.com/31094))

   * `REGEXP' operations could cause a server crash for character sets
     such as `ucs2'.  Now the arguments are converted to `utf8' if
     possible, to allow correct results to be produced if the resulting
     strings contain only 8-bit characters.  (Bug#31081
     (http://bugs.mysql.com/31081))

   * Expressions of the form `WHERE COL NOT IN (COL, ...)', where the
     same column was named both times, could cause a server crash in the
     optimizer.  (Bug#31075 (http://bugs.mysql.com/31075))

   * `Falcon' failed to compile on FreeBSD.  (Bug#31045
     (http://bugs.mysql.com/31045))

   * Using `ORDER BY' with `ARCHIVE' tables caused a server crash.
     (Bug#31036 (http://bugs.mysql.com/31036))

   * The `MOD()' function and the `%' operator crashed the server for a
     divisor less than 1 with a very long fractional part.  (Bug#31019
     (http://bugs.mysql.com/31019))

   * Using `falcon_serial_log_dir' to set the location of the `Falcon'
     serial log would have no effect.  (Bug#31005
     (http://bugs.mysql.com/31005))

   * The LooseScan subquery optimization strategy could produce
     duplicate rows in query results.  (Bug#30993
     (http://bugs.mysql.com/30993))

   * A character set introducer followed by a hexadecimal or bit-value
     literal did not check its argument and could return an ill-formed
     result for invalid input.  (Bug#30986
     (http://bugs.mysql.com/30986))

   * `CHAR(STR USING CHARSET)' did not check its argument and could
     return an ill-formed result for invalid input.  (Bug#30982
     (http://bugs.mysql.com/30982))

   * The result from `CHAR(STR USING ucs2') did not add a leading 0x00
     byte for input strings with an odd number of bytes.  (Bug#30981
     (http://bugs.mysql.com/30981))

   * The `GeomFromText()' function could cause a server crash if the
     first argument was `NULL' or the empty string.  (Bug#30955
     (http://bugs.mysql.com/30955))

   * When invoked with constant arguments, `STR_TO_DATE()' could use a
     cached value for the format string and return incorrect results.
     (Bug#30942 (http://bugs.mysql.com/30942))

   * `GROUP_CONCAT()' returned `','' rather than an empty string when
     the argument column contained only empty strings.  (Bug#30897
     (http://bugs.mysql.com/30897))

   * A server crash could occur if a stored function that contained a
     `DROP TEMPORARY TABLE' statement was invoked by a *Note `CREATE
     TEMPORARY TABLE': create-table. statement that created a table of
     the same name.  (Bug#30882 (http://bugs.mysql.com/30882))

   * Calling `NAME_CONST()' with non-constant arguments triggered an
     assertion failure.  Non-constant arguments are now disallowed.
     (Bug#30832 (http://bugs.mysql.com/30832))

   * Running `ALTER TABLE ... OPTIMIZE PARTITION' on a `Falcon' table,
     a 'divide by zero' error would be reported during a server crash.
     (Bug#30826 (http://bugs.mysql.com/30826))

   * For a spatial column with a regular (non-`SPATIAL') index, queries
     failed if the optimizer tried to use the index.  (Bug#30825
     (http://bugs.mysql.com/30825))

   * *Note `INFORMATION_SCHEMA.SCHEMATA': schemata-table. was returning
     incorrect information.  (Bug#30795 (http://bugs.mysql.com/30795))

   * On Windows, the `pthread_mutex_trylock()' implementation was
     incorrect. One symptom was that invalidating the query cache could
     cause a server crash.  (Bug#30768 (http://bugs.mysql.com/30768))

   * A multiple-table *Note `UPDATE': update. involving transactional
     and non-transactional tables caused an assertion failure.
     (Bug#30763 (http://bugs.mysql.com/30763))

   * Under some circumstances, `CREATE TABLE ...  SELECT' could crash
     the server or incorrectly report that the table row size was too
     large.  (Bug#30736 (http://bugs.mysql.com/30736))

   * Using the `MIN()' or `MAX()' function to select one part of a
     multi-part key could cause a crash when the function result was
     `NULL'.  (Bug#30715 (http://bugs.mysql.com/30715))

   * `INFORMATION_SCHEMA.VIEWS.VIEW_DEFINITION' was incorrect for views
     that were defined to select from other `INFORMATION_SCHEMA' tables.
     (Bug#30689 (http://bugs.mysql.com/30689))

   * Issuing an *Note `ALTER SERVER': alter-server. statement to update
     the settings for a `FEDERATED' server would cause the *Note
     `mysqld': mysqld. to crash.  (Bug#30671
     (http://bugs.mysql.com/30671))

   * The optimizer could ignore `ORDER BY' in cases when the result set
     is ordered by `filesort', resulting in rows being returned in
     incorrect order.  (Bug#30666 (http://bugs.mysql.com/30666))

   * A different execution plan was displayed for *Note `EXPLAIN':
     explain. than would actually have been used for the *Note
     `SELECT': select. because the test of sort keys for `ORDER BY' did
     not consider keys mentioned in `IGNORE KEYS FOR ORDER BY'.
     (Bug#30665 (http://bugs.mysql.com/30665))

   * `MyISAM' tables could not exceed 4294967295 (2^32 - 1) rows on
     Windows.  (Bug#30638 (http://bugs.mysql.com/30638))

   * `mysql-test-run.pl' could not run *Note `mysqld': mysqld. with
     `root' privileges.  (Bug#30630 (http://bugs.mysql.com/30630))

   * Using `GROUP BY' on an expression of the form `TIMESTAMP_COL DIV
     NUMBER' caused a server crash due to incorrect calculation of
     number of decimals.  (Bug#30587 (http://bugs.mysql.com/30587))

   * The options available to the *Note `CHECK TABLE': check-table.
     statement were also allowed in *Note `OPTIMIZE TABLE':
     optimize-table. and *Note `ANALYZE TABLE': analyze-table.
     statements, but caused corruption during their execution. These
     options were never supported for these statements, and an error is
     now raised if you try to apply these options to these statements.
     (Bug#30495 (http://bugs.mysql.com/30495))

   * When expanding a `*' in a `USING' or `NATURAL' join, the check for
     table access for both tables in the join was done using only the
     grant information of the first table.  (Bug#30468
     (http://bugs.mysql.com/30468))

   * Compared to MySQL 5.1, the 6.0 optimizer failed to use join
     buffering for certain queries, resulting in slower performance for
     those queries.  (Bug#30363 (http://bugs.mysql.com/30363))

   * A table-access check was performed improperly by `libmysqld',
     causing a crash.  (Bug#30329 (http://bugs.mysql.com/30329))

   * Some valid `euc-kr' characters having the second byte in the
     ranges `[0x41..0x5A]' and `[0x61..0x7A]' were rejected.
     (Bug#30315 (http://bugs.mysql.com/30315))

   * When loading a dynamic plugin on FreeBSD, the plugin would fail to
     load. This was due to a build error where the required symbols
     would be not exported correctly.  (Bug#30296
     (http://bugs.mysql.com/30296))

   * Setting certain values on a table using a spatial index could
     cause the server to crash.  (Bug#30286
     (http://bugs.mysql.com/30286))

   * It was not possible for client applications to distinguish between
     auto-set and auto-updated *Note `TIMESTAMP': datetime. column
     values.

     To rectify this problem, a new `ON_UPDATE_NOW_FLAG' flag is set by
     Field_timestamp constructors whenever a column should be set to
     `NOW' on *Note `UPDATE': update, and the
     `get_schema_column_record()' function now reports whether a
     timestamp column is set to `NOW' on *Note `UPDATE': update.  In
     addition, such columns now display `on update CURRENT_TIMESTAMP'
     in the `Extra' column in the output from *Note `SHOW COLUMNS':
     show-columns.  (Bug#30081 (http://bugs.mysql.com/30081))

   * Some `INFORMATION_SCHEMA' tables are intended for internal use,
     but could be accessed by using *Note `SHOW': show. statements.
     (Bug#30079 (http://bugs.mysql.com/30079))

   * On some 64-bit systems, inserting the largest negative value into
     a *Note `BIGINT': numeric-types. column resulted in incorrect data.
     (Bug#30069 (http://bugs.mysql.com/30069))

   * *Note `mysqlslap': mysqlslap. did not properly handle multiple
     result sets from stored procedures.  (Bug#29985
     (http://bugs.mysql.com/29985))

   * Running the `sqlbench' test suite against `Falcon' would cause a
     crash.  (Bug#29870 (http://bugs.mysql.com/29870))

   * When accessing the statistics in
     `INFORMATION_SCHEMA.FALCON_DATABASE_IO', the information related
     only to the `Falcon' database, and not to user tablespaces. The
     output has been updated to report on all tablespaces, and the
     `DATABASE' column has been renamed to `TABLESPACE' to reflect the
     fact that these statistics are now reported by tablespace, not by
     database.  (Bug#29823 (http://bugs.mysql.com/29823))

   * Whitespace characters other than spaces within XML tags, such as
     linefeeds or tabs, caused `LOAD XML INFILE' to skip rows.
     (Bug#29752 (http://bugs.mysql.com/29752))

   * `configure' did not find `nss' on some Linux platforms.
     (Bug#29658 (http://bugs.mysql.com/29658))

   * Compilation failed on systems where a native `log2()'
     implementation was unavailable.  (Bug#29640
     (http://bugs.mysql.com/29640))

   * Use of the `latin2_czech_cs' collation caused a server crash.
     (Bug#29459 (http://bugs.mysql.com/29459))

   * Using two simultaneous connections it was possible to create a
     deadlock situation between two different active transactions on
     the same `Falcon' table. There is no way to prevent this, but a
     new parameter, `falcon_lock_timeout' can set the timeout for
     deadlocked transactions. The default timeout is 0 (timeouts are
     disabled).  (Bug#29452 (http://bugs.mysql.com/29452))

   * The *Note `mysql': mysql. client program now ignores Unicode byte
     order mark (BOM) characters at the beginning of input files.
     Previously, it read them and sent them to the server, resulting in
     a syntax error.

     Presence of a BOM does not cause *Note `mysql': mysql. to change
     its default character set. To do that, invoke *Note `mysql':
     mysql. with an option such as `--default-character-set=utf8'.
     (Bug#29323 (http://bugs.mysql.com/29323))

   * Inserting information into the same table from multiple threads
     could cause duplicate key errors. This was related to the changes
     made to allow compatibility with the `InnoDB' repeatable-read
     isolation level. The option, `falcon_innodb_compatibility', has
     been renamed to `falcon_consistent_read', but with the opposite
     effect. The default is for this option to be on. When set to off,
     the behavior of `Falcon' is similar to that in `InnoDB'.
     (Bug#29151 (http://bugs.mysql.com/29151))

   * For transactional tables, an error during a multiple-table *Note
     `DELETE': delete. statement did not roll back the statement.
     (Bug#29136 (http://bugs.mysql.com/29136))

   * The `log' and `log_slow_queries' system variables were displayed
     by *Note `SHOW VARIABLES': show-variables. but could not be
     accessed in expressions as `@@log' and `@@log_slow_queries'. Also,
     attempting to set them with `SET' produced an incorrect `Unknown
     system variable' message. Now these variables are treated as
     synonyms for `general_log' and `slow_query_log', which means that
     they can be accessed in expressions and their values can be
     changed with `SET'.  (Bug#29131 (http://bugs.mysql.com/29131))

   * When loading large data sets using *Note `LOAD DATA INFILE':
     load-data. into a `Falcon' table, the server could crash.
     (Bug#29081 (http://bugs.mysql.com/29081))

   * *Note `SHOW VARIABLES': show-variables. did not display the
     `relay_log', `relay_log_index', or `relay_log_info_file' system
     variables.  (Bug#28893 (http://bugs.mysql.com/28893))

   * Index hints specified in view definitions were ignored when using
     the view to select from the base table.  (Bug#28702
     (http://bugs.mysql.com/28702))

   * Views do not have indexes, so index hints do not apply. Use of
     index hints when selecting from a view is now disallowed.
     (Bug#28701 (http://bugs.mysql.com/28701))

   * After changing the SQL mode to a restrictive value that would make
     already-inserted dates in a column be considered invalid, searches
     returned different results depending on whether the column was
     indexed.  (Bug#28687 (http://bugs.mysql.com/28687))

   * The result from `CHAR()' was incorrectly assumed in some contexts
     to return a single-byte result.  (Bug#28550
     (http://bugs.mysql.com/28550))

   * Using a temporary table within `Falcon' that is created in a
     directory where the path contains a mixture of upper and lower
     letters would fail.  (Bug#28541 (http://bugs.mysql.com/28541))

   * Under heavy load when updating `Falcon' tables, a race condition
     could occur that would ultimately result in a crash.  (Bug#28519
     (http://bugs.mysql.com/28519))

   * The result of a comparison between *Note `VARBINARY':
     binary-varbinary. and *Note `BINARY': binary-varbinary. columns
     differed depending on whether the *Note `VARBINARY':
     binary-varbinary. column was indexed.  (Bug#28076
     (http://bugs.mysql.com/28076))

   * The metadata in some `MYSQL_FIELD' members could be incorrect when
     a temporary table was used to evaluate a query.  (Bug#27990
     (http://bugs.mysql.com/27990))

   * `ALTER TABLE TBL_NAME ROW_FORMAT=FORMAT_TYPE' did not cause the
     table to be rebuilt.  (Bug#27610 (http://bugs.mysql.com/27610))

   * Searching a `Falcon' table that uses *Note `DATETIME': datetime.
     columns with an index could return incorrect results.  (Bug#27426
     (http://bugs.mysql.com/27426))

   * Removing a partition on a `Falcon' table when there are two tables
     with the same name, but different case, would cause a crash during
     normal shutdown.  (Bug#27425 (http://bugs.mysql.com/27425))

   * Mixing differently cased tables between `MyISAM' and `Falcon'
     tables would cause a crash.  (Bug#27424
     (http://bugs.mysql.com/27424))

   * The `ExtractValue()' and `UpdateXML()' functions performed
     extremely slowly for large amounts of XML data (greater than 64
     KB). These functions now execute approximately 2000 times faster
     than previously.  (Bug#27287 (http://bugs.mysql.com/27287))

   * On Windows, writes to the debug log were using `freopen()' instead
     of `fflush()', resulting in slower performance.  (Bug#27099
     (http://bugs.mysql.com/27099))

   * The MySQL Instance Configuration Wizard would not allow you to
     choose a service name, even though the criteria for the service
     name were valid. The code that checks the name has been updated to
     support the correct criteria of any string less than 256 character
     and not containing either a forward or backward slash character.
     (Bug#27013 (http://bugs.mysql.com/27013))

   * *Note `LOAD DATA INFILE': load-data. ran very slowly when reading
     large files into partitioned tables.  (Bug#26527
     (http://bugs.mysql.com/26527))

   * Threads that were calculating the estimated number of records for
     a range scan did not respond to the *Note `KILL': kill. statement.
     That is, if a `range' join type is possible (even if not selected
     by the optimizer as a join type of choice and thus not shown by
     *Note `EXPLAIN': explain.), the query in the `statistics' state
     (shown by the *Note `SHOW PROCESSLIST': show-processlist.) did not
     respond to the *Note `KILL': kill. statement.  (Bug#25421
     (http://bugs.mysql.com/25421))

   * For *Note `mysql --show-warnings': mysql, warnings were in some
     cases not displayed.  (Bug#25146 (http://bugs.mysql.com/25146))

   * Using `CREATE UNIQUE INDEX' on a `Falcon' table where rows contain
     duplicate values could result in pending transactions to the table
     being deleted.  (Bug#22842 (http://bugs.mysql.com/22842))

   * Creating a `Falcon' table with an auto-increment column that is
     not indexed as the first column in a multi-column index would
     auto-increment. This behavior was different to the behavior in
     both `MyISAM' and `InnoDB'. `Falcon' now rejects such tables
     during creation in the same way `InnoDB' does.  (Bug#22564
     (http://bugs.mysql.com/22564))

   * For storage engines that do not redefine
     `handler::index_next_same()' and are capable of indexes,
     statements that include a `WHERE' clause might select incorrect
     data.  (Bug#22351 (http://bugs.mysql.com/22351))

   * Creating a new table or dropping a database on a newly created
     `Falcon' database or tablespace raised an error.  (Bug#22199
     (http://bugs.mysql.com/22199))

   * Using *Note `TRUNCATE': truncate. on a `Falcon' table did not
     reset the auto-increment counters and used an inefficient method
     of deleting existing data.  (Bug#22173
     (http://bugs.mysql.com/22173))

   * Creating a *Note `DATE': datetime. outside the normal range within
     a `Falcon' table would result in a zero *Note `DATE': datetime.
     value being returned, even though normally invalid values would be
     stored correctly in other storage engines.  (Bug#22168
     (http://bugs.mysql.com/22168))

   * Selecting information from a `Falcon' table using a *Note
     `DOUBLE': numeric-types. column with an index would produce
     incorrect results.  (Bug#22125 (http://bugs.mysql.com/22125))

   * The `readline' library has been updated to version 5.2. This
     addresses issues in the *Note `mysql': mysql. client where history
     and editing within the client would fail to work as expected.
     (Bug#18431 (http://bugs.mysql.com/18431))

   * *Note `mysql': mysql. stripped comments from statements sent to
     the server. Now the `--comments' or `--skip-comments' option can be
     used to control whether to retain or strip comments. The default
     is `--skip-comments'.  (Bug#11230 (http://bugs.mysql.com/11230),
     Bug#26215 (http://bugs.mysql.com/26215))

   * Executing `DISABLE KEYS' and `ENABLE KEYS' on a non-empty table
     would cause the size of the index file for the table to grow
     considerable. This was because the `DISABLE KEYS' operation would
     only mark the existing index, without deleting the index blocks.
     The `ENABLE KEYS' operation would re-create the index, adding new
     blocks, while the previous index blocks would remain. Existing
     indexes are now dropped and recreated when the `ENABLE KEYS'
     statement is executed.  (Bug#4692 (http://bugs.mysql.com/4692))


File: manual.info,  Node: news-6-0-3,  Next: news-6-0-2,  Prev: news-6-0-4,  Up: news-6-0-x

C.1.9 Changes in MySQL 6.0.3 (16 November 2007)
-----------------------------------------------

Functionality added or changed:

   * *Incompatible Change*: Aliases for wildcards (as in `SELECT t.* AS
     'alias' FROM t') are no longer accepted and result in an error.
     Previously, such aliases were ignored silently.  (Bug#27249
     (http://bugs.mysql.com/27249))

   * Sinhala collations `utf8_sinhala_ci' and `ucs2_sinhala_ci' were
     added for the `utf8' and `ucs2' character sets.  (Bug#26474
     (http://bugs.mysql.com/26474))

   * If the value of the `--log-warnings' option is greater than 1, the
     server now writes access-denied errors for new connection attempts
     to the error log (for example, if a client user name or password
     is incorrect).  (Bug#25822 (http://bugs.mysql.com/25822))

   * Added the *Note `PARAMETERS': parameters-table. table to
     `INFORMATION_SCHEMA'. The *Note `PARAMETERS': parameters-table.
     table provides information about stored function and procedure
     parameters, and about return values for stored functions.

Bugs fixed:

   * *Incompatible Change*: *Note `DROP TABLE': drop-table. now is
     allowed only if you have acquired a `WRITE' lock with *Note `LOCK
     TABLES': lock-tables, or if you hold no locks, or if the table is
     a `TEMPORARY' table.

     Previously, if other tables were locked, you could drop a table
     with a read lock or no lock, which could lead to deadlocks between
     clients. The new stricter behavior means that some usage scenarios
     will fail when previously they did not.  (Bug#25858
     (http://bugs.mysql.com/25858))

   * *Incompatible Change*: *Note `GRANT': grant. and *Note `REVOKE':
     revoke. statements now cause an implicit commit, and thus are
     prohibited within stored functions and triggers.  (Bug#21975
     (http://bugs.mysql.com/21975), Bug#21422
     (http://bugs.mysql.com/21422), Bug#17244
     (http://bugs.mysql.com/17244))

   * *MySQL Cluster*: Adding a new *Note `TINYTEXT': blob. column to an
     `NDB' table which used `COLUMN_FORMAT = DYNAMIC', and when binary
     logging was enabled, caused all cluster *Note `mysqld': mysqld.
     processes to crash.  (Bug#30213 (http://bugs.mysql.com/30213))

   * *MySQL Cluster*: After adding a new column of one of the *Note
     `TEXT': blob. or *Note `BLOB': blob. types to an `NDB' table which
     used `COLUMN_FORMAT = DYNAMIC', it was no longer possible to
     access or drop the table using SQL.  (Bug#30205
     (http://bugs.mysql.com/30205))

   * The server crashed on optimization of queries that compared an
     indexed *Note `DECIMAL': numeric-types. column with a string value.
     (Bug#32262 (http://bugs.mysql.com/32262))

   * The server crashed on optimizations that used the `range checked
     for each record' access method.  (Bug#32229
     (http://bugs.mysql.com/32229))

   * When comparing a *Note `BLOB': blob. value that was null, memory
     corruption could occur casuing the server to crash.  (Bug#32191
     (http://bugs.mysql.com/32191))

   * Deleting a large number of records could sometimes take a
     significant amount of time.  (Bug#27946
     (http://bugs.mysql.com/27946))

   * Several buffer-size system variables were either being handled
     incorrectly for large values (for settings larger than 4GB, they
     were truncated to values less than 4GB without a warning), or were
     limited unnecessarily to 4GB even on 64-bit systems. The following
     changes were made:

        * For `key_buffer_size', values larger than 4GB are allowed on
          64-bit platforms.

        * For `join_buffer_size', `sort_buffer_size', and
          `myisam_sort_buffer_size', values larger than 4GB are allowed
          on 64-bit platforms (except Windows, for which large values
          are truncated to 4GB with a warning).

     In addition, settings for `read_buffer_size' and
     `read_rnd_buffer_size' are limited to 2GB on all platforms. Larger
     values are truncated to 2GB with a warning.  (Bug#5731
     (http://bugs.mysql.com/5731), Bug#29419
     (http://bugs.mysql.com/29419), Bug#29446
     (http://bugs.mysql.com/29446))


File: manual.info,  Node: news-6-0-2,  Next: news-6-0-1,  Prev: news-6-0-3,  Up: news-6-0-x

C.1.10 Changes in MySQL 6.0.2 (04 September 2007)
-------------------------------------------------

Functionality added or changed:

   * Mac OS X (Intel) support has been added. To build on Mac OS X from
     the repository sources you must have the most recent versions of
     `bison', `automake', `autoconf' and `libtool' installed.

     There are known issues with the Falcon on Mac OS X build.
     (Bug#30564 (http://bugs.mysql.com/30564))

   * The Falcon record cache parameters have been altered. The
     `falcon_max_record_memory' and `falcon_min_record_memory' are no
     longer supported.

     Instead, the `falcon_record_memory_max',
     `falcon_record_scavenge_threshold', `falcon_record_scavenge_floor'
     and `falcon_inital_allocation' parameters are now used to control
     the caching of records in memory within Falcon. See *Note
     se-falcon-configuration::.  (Bug#30083
     (http://bugs.mysql.com/30083))

   * 64-bit Windows support.

   * Support for tablespaces.

   * New performance settings, `falcon_log_windows',
     `falcon_index_chill_threshold', and
     `falcon_record_chill_threshold'.

   * The option `falcon_disable_fsync' has been added. If set to true,
     then the periodic fsync operation is disabled.

   * The option `falcon_initial_allocation' has been added to control
     the initial size of a Falcon tablespace on disk.

Bugs fixed:

   * An assertion could be thrown during high number of concurrent
     updates of *Note `BLOB': blob. fields.  (Bug#30463
     (http://bugs.mysql.com/30463))

   * When loading large data sets into a Falcon table *Note `mysqld':
     mysqld. could crash. An Out of memory error will now be raised in
     this situation.  (Bug#30251 (http://bugs.mysql.com/30251),
     Bug#30074 (http://bugs.mysql.com/30074))

   * Falcon would incorrectly allow creation of two tables with the
     same name but different case sensitivity, without raising an
     error, but treat the two tables as the same during further
     queries. .  (Bug#30210 (http://bugs.mysql.com/30210))

   * Updating a large table without an index would lock all the records
     during a transaction and unlock the records individually.
     (Bug#30124 (http://bugs.mysql.com/30124))

   * Creating a tablespace with a unique name but using the same data
     file as an existing tablespace results in the re-initialization of
     the tablespace and the loss of the data contained in it.  Falcon
     now reports an error if the data file already exists.  (Bug#29511
     (http://bugs.mysql.com/29511))

   * Using *Note `SELECT': select. on a table that uses two *Note
     `INT': numeric-types. columns with a single index would fail to
     return rows that queried both columns and complex comparison
     operators.  (Bug#29319 (http://bugs.mysql.com/29319))

   * Falcon could occasionally report a problem with a duplicate key
     error during *Note `INSERT': insert. when inserting the same data
     into a unique column on two or more connections simultaneously.
     (Bug#29240 (http://bugs.mysql.com/29240))

   * Inserting into a table with a unique index simultaneously on two
     connections in a way that would cause a deadlock would cause MySQL
     to hang. The deadlock situation is now identified and an error
     will be raised.  (Bug#29206 (http://bugs.mysql.com/29206))

   * Wide *Note `DECIMAL': numeric-types. columns would show rounding
     errors during *Note `SELECT': select.  (Bug#29201
     (http://bugs.mysql.com/29201))

   * Some Falcon variables were marked as status variables.  (Bug#29169
     (http://bugs.mysql.com/29169))

   * Accessing an `INFORMATION_SCHEMA' table generated by Falcon, when
     Falcon has not been enabled would cause *Note `mysqld': mysqld. to
     crash.  (Bug#29014 (http://bugs.mysql.com/29014))

   * For debug builds, the server crashed when inserting a negated
     *Note `DECIMAL': numeric-types. value of maximum precision (65
     digits), such as for `INSERT INTO ...  SELECT -col_val ...'
     (Bug#28810 (http://bugs.mysql.com/28810))

   * Accessing data within *Note `DECIMAL': numeric-types.  columns
     wider than 18 digits would cause a crash.  (Bug#28725
     (http://bugs.mysql.com/28725))

   * *Note `mysqld': mysqld. would crash after a high number of *Note
     `ALTER TABLE': alter-table, *Note `INSERT': insert. and *Note
     `UPDATE': update.statements.  (Bug#28515
     (http://bugs.mysql.com/28515), Bug#22154
     (http://bugs.mysql.com/22154))

   * Unique indexes on *Note `VARCHAR': char. columns are not
     identified correctly.  (Bug#28500 (http://bugs.mysql.com/28500))

   * Under certain situations the Falcon tables and log could become
     corrupt and prevent recovery from a crashed version of the files.
     (Bug#28351 (http://bugs.mysql.com/28351))

   * The value for `FALCON_SYSTEM_MEMORY_SUMMARY.TOTAL_SPACE' in
     `INFORMATION_SCHEMA' would be reported incorrectly.  (Bug#28197
     (http://bugs.mysql.com/28197))

   * Searching for rows within a table with some non-western character
     sets would fail to return the right results if the *Note `SELECT':
     select. relied on an index.  (Bug#27697
     (http://bugs.mysql.com/27697))

   * Inserting large numbers of identical columns into a table,
     followed by a *Note `SELECT': select. or *Note `UPDATE': update.
     could cause a hang or crash.  (Bug#27277
     (http://bugs.mysql.com/27277))

   * Loading certain data sets through a direct import could cause
     index problems and crash.  (Bug#26930
     (http://bugs.mysql.com/26930))

   * *Note `DECIMAL': numeric-types. columns with large widths did not
     work, either during *Note `INSERT': insert. or *Note `SELECT':
     select.  (Bug#26607 (http://bugs.mysql.com/26607))

   * *Note `DELETE': delete. statements could cause a crash when many
     simultaneous threads are running.  (Bug#26475
     (http://bugs.mysql.com/26475))

   * Falcon would fail to build under Mac OS X/Intel. A preliminary
     patch is available to allow building under Mac OS X/Intel only
     (PowerPC support is not yet available). Note that Mac OS X/Intel
     is still an unsupported platform.  (Bug#26466
     (http://bugs.mysql.com/26466))

   * Queries could fail with a `Can't find record in ...' error.
     (Bug#26328 (http://bugs.mysql.com/26328))

   * Under certain situations, shutting down MySQL using *Note
     `mysqladmin': mysqladmin. could cause Falcon to corrupt the
     database tables and fail to restart properly.  (Bug#26296
     (http://bugs.mysql.com/26296))

   * Searches for accented characters in a UTF8 table fail if an index
     exists for the column.  (Bug#26057 (http://bugs.mysql.com/26057))

   * Searches using `LIKE' on a UTF8 table fail if the search relies an
     indexed column.  (Bug#24921 (http://bugs.mysql.com/24921))

   * Searches for data on a partial index for a column using the UTF8
     character set would fail.  (Bug#24858
     (http://bugs.mysql.com/24858))

   * Searches for data using exotic collation/character sets fail if
     the search relies on an indexed column.  (Bug#23689
     (http://bugs.mysql.com/23689))

   * Inserting rows to a table with a unique index where the unique
     index value is identical on two separate connections would block
     the second transaction.  (Bug#22847 (http://bugs.mysql.com/22847))

   * Renaming a database would raise error `ERROR 1030 (HY000): Got
     error 157 from storage engine'.  (Bug#22182
     (http://bugs.mysql.com/22182))

   * Large inserts to a table within a single transaction trigger high
     memory usage and may ultimately crash.  (Bug#22169
     (http://bugs.mysql.com/22169))

   * Renaming tables to or from Falcon tablespaces raised an error.
     (Bug#22155 (http://bugs.mysql.com/22155))


File: manual.info,  Node: news-6-0-1,  Next: news-6-0-0,  Prev: news-6-0-2,  Up: news-6-0-x

C.1.11 Changes in MySQL 6.0.1 (Not released)
--------------------------------------------

This was an internal release only, and no binaries were published.


File: manual.info,  Node: news-6-0-0,  Prev: news-6-0-1,  Up: news-6-0-x

C.1.12 Changes in MySQL 6.0.0 (30 April 2007 Alpha)
---------------------------------------------------

Functionality added or changed:

   * *Note `SELECT ... FOR UPDATE': select. is now supported.

   * Uncommitted record scavenging has been implemented.

   * Performance diagnostics are available through `INFORMATION_SCHEMA'.

Bugs fixed:

   * Using *Note `SELECT ... FOR UPDATE': select. and *Note `ROLLBACK':
     commit. could cause `mysqld' to hang indefinitely.  (Bug#28165
     (http://bugs.mysql.com/28165))

   * Concurrent updates on two different connections could lead to an
     assertion failure.  (Bug#28090 (http://bugs.mysql.com/28090))

   * Updating a row within a table that has a unique compound index to
     a non-unique value would not raise an error.  (Bug#27997
     (http://bugs.mysql.com/27997))

   * Rolling back an inserted row while accessing the same on a
     different connection would cause a crash.  (Bug#27993
     (http://bugs.mysql.com/27993))

   * Creating a table with a 19 digit *Note `DECIMAL': numeric-types.
     column would cause incorrect data to be stored. This is due to
     current limitation in Falcon where you cannot create a table with
     a column with greater than 18 digits precision (i.e.
     `DECIMAL(18,9)'). Creating a column with larger than this
     specification will fail and raise an error.  (Bug#27962
     (http://bugs.mysql.com/27962))

   * Executing `INSERT INTO ... SELECT FROM' could cause a crash on
     large data sets.  (Bug#27951 (http://bugs.mysql.com/27951))

   * Inserting data into the same table on two different connections
     with autocommit disabled would cause a crash.  (Bug#27895
     (http://bugs.mysql.com/27895))

   * Creating a Falcon table immediately after creating a new database
     could cause a crash.  (Bug#27768 (http://bugs.mysql.com/27768))

   * Executing *Note `SELECT ... FOR UPDATE': select. in a second
     connection on a newly created and populated table could cause a
     crash.  (Bug#27767 (http://bugs.mysql.com/27767))

   * Continually updating a *Note `BLOB': blob.  column would cause
     MySQL server to crash.  (Bug#27719 (http://bugs.mysql.com/27719))

   * Using a trigger on an *Note `UPDATE': update. to a Falcon table
     when autocommit is disabled would cause MySQL server to crash.
     (Bug#27574 (http://bugs.mysql.com/27574))

   * Interrupting a stored procedure during execution could cause a
     crash.  (Bug#27539 (http://bugs.mysql.com/27539))

   * Opening the same database with Falcon tables on a different
     connection could cause a crash.  (Bug#27428
     (http://bugs.mysql.com/27428))

   * Using *Note `ROLLBACK': commit.  after a *Note `DELETE': delete.
     does not restore the deleted row.  (Bug#27357
     (http://bugs.mysql.com/27357))

   * Two simultaneous *Note `SELECT ... FOR UPDATE': select. statements
     with `READ COMMITTED' isolation level would result in the wrong
     error message being returned.  (Bug#26871
     (http://bugs.mysql.com/26871))

   * Row insertions to a table with long *Note `VARCHAR': char. columns
     and large compound indexes would cause MySQL to crash.  (Bug#26850
     (http://bugs.mysql.com/26850))

   * Falcon could consume large amounts of memory during a high number
     of continuous *Note `INSERT': insert.  statements.  (Bug#26843
     (http://bugs.mysql.com/26843))

   * Updating a partitioned table in two sessions simultaneously would
     cause MySQL to crash.  (Bug#26828 (http://bugs.mysql.com/26828))

   * Locking between sessions when using *Note `SELECT ... FOR UPDATE':
     select. would not work.  (Bug#26826 (http://bugs.mysql.com/26826))

   * Tables with `UNIQUE' key constraints would not be enforced.
     (Bug#26803 (http://bugs.mysql.com/26803))

   * When updating a table with a unique key constraint the constraint
     would not be enforced.  (Bug#26802 (http://bugs.mysql.com/26802))

   * Searching for records in a table with a `DECIMAL(6,6)' column
     would fail to find the value.  (Bug#26469
     (http://bugs.mysql.com/26469))

   * Rows with a numeric column may fail to find records with zero
     values.  (Bug#26468 (http://bugs.mysql.com/26468))

   * Retrieving rows from a table that used an index would sometimes
     fail to return the row.  (Bug#26452 (http://bugs.mysql.com/26452))

   * Continue handlers in stored procedures could cause a crash.
     (Bug#26433 (http://bugs.mysql.com/26433))

   * Tables with a long multi-column index may fail to find a record
     for *Note `UPDATE': update.  (Bug#26420
     (http://bugs.mysql.com/26420))

   * Updating *Note `BLOB': blob. columns could result in a crash.
     (Bug#26324 (http://bugs.mysql.com/26324))

   * Deleting a large quantity of rows in a single table may result in
     `ERROR 1020'.  (Bug#26055 (http://bugs.mysql.com/26055))

   * A *Note `DROP TABLE': drop-table. statement on a table created
     using `CREATE TABLE ... SELECT ...' crashed the server.
     (Bug#25564 (http://bugs.mysql.com/25564))

   * Random updates of `LONG VARCHAR' columns would fail.  (Bug#23818
     (http://bugs.mysql.com/23818))

   * Running *Note `SELECT': select. after a changing the table
     contents does not result in a new data set.  (Bug#22181
     (http://bugs.mysql.com/22181))

   * Using *Note `ALTER TABLE': alter-table. with interleaving
     transactions could cause *Note `mysqld': mysqld.  to crash.
     (Bug#22165 (http://bugs.mysql.com/22165))


File: manual.info,  Node: news-5-2-x,  Next: mem-news,  Prev: news-6-0-x,  Up: news

C.2 Changes in release 5.2.x (Development)
==========================================

* Menu:

* news-5-2-5::                   Changes in MySQL 5.2.5 (08 August 2007)
* news-5-2-4::                   Changes in MySQL 5.2.4 (Not released)
* news-5-2-3::                   Changes in MySQL 5.2.3 (15 February 2007)
* news-5-2-2::                   Changes in MySQL 5.2.2 (Not released)
* news-5-2-1::                   Changes in MySQL 5.2.1 (Not released Alpha)

MySQL 5.2 was merged into MySQL 6.0. An overview of which features were
added in MySQL 5.2 and MySQL 6.0 can be found here: *Note
mysql-nutshell::.

For a full list of changes, please refer to the changelog sections for
each individual 5.2.x release.


File: manual.info,  Node: news-5-2-5,  Next: news-5-2-4,  Prev: news-5-2-x,  Up: news-5-2-x

C.2.1 Changes in MySQL 5.2.5 (08 August 2007)
---------------------------------------------

This is a new Alpha development release, fixing recently discovered
bugs.

*Note*:

This Alpha release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Network_ (a commercial MySQL offering). For more
details please see
`http://www.mysql.com/products/enterprise/advisors.html'.

Functionality added or changed:

   * *Incompatible Change*: The obsolete constructs in the following
     table have been removed. Use the equivalents shown in the table's
     second column instead. Existing applications that depend on the
     obsolete constructs should be converted to make use of the current
     equivalents as soon as possible.

     *Obsolete*:                        *Current*:
     `@@table_type'                     `@@storage_engine'
     `@@log_bin_trust_routine_creators' `@@log_bin_trust_function_creators'
     `TIMESTAMP(N)'                     See *Note
                                        date-and-time-functions::.
     `TYPE='                            `ENGINE='
     `BACKUP TABLE'                     *Note `mysqldump': mysqldump,
     (http://dev.mysql.com/doc/refman/5.1/en/backup-table.html)*Note `mysqlhotcopy':
                                        mysqlhotcopy, or MySQL
                                        Administrator
     `RESTORE TABLE'                    *Note `mysqldump': mysqldump,
     (http://dev.mysql.com/doc/refman/5.1/en/restore-table.html),*Note `mysql': mysql, or MySQL
     `LOAD TABLE FROM MASTER'           Administrator
     `SHOW TABLE TYPES'                 `SHOW [STORAGE] ENGINES'
     `SHOW INNODB STATUS'               *Note `SHOW ENGINE INNODB
     (http://dev.mysql.com/doc/refman/5.1/en/show-innodb-status.html)STATUS': show-engine.
     `SHOW MUTEX STATUS'                *Note `SHOW ENGINE INNODB MUTEX':
                                        show-engine.
     `--master-XXX' options to set      *Note `CHANGE MASTER TO':
     replication parameters:            change-master-to.
     `--master-host', `--master-user',  
     `--master-password ',              
     `--master-port',                   
     `--master-connect-retry',          
     `--master-ssl', `--master-ssl-ca', 
     `--master-ssl-capath',             
     `--master-ssl-cert',               
     `--master-ssl-cipher',             
     `--master-ssl-key'                 

   * *MySQL Cluster*: It is now possible to control whether fixed-width
     or variable-width storage is used for a given column of an `NDB'
     table by means of the `COLUMN_FORMAT' specifier as part of the
     column's definition in a *Note `CREATE TABLE': create-table. or
     *Note `ALTER TABLE': alter-table.  statement.

     It is also possible to control whether a given column of an `NDB'
     table is stored in memory or on disk, using the `STORAGE'
     specifier as part of the column's definition in a *Note `CREATE
     TABLE': create-table. or *Note `ALTER TABLE': alter-table.
     statement.

     For permitted values and other information about `COLUMN_FORMAT'
     and `STORAGE', see *Note create-table::.

   * The *Note `INFORMATION_SCHEMA.COLUMNS': columns-table.  table now
     has `STORAGE' and `FORMAT' columns. For `NDB' tables, `STORAGE'
     indicates whether a column is stored on disk or memory, and
     `FORMAT' indicates the column storage format (*Note `FIXED':
     numeric-types, `DYNAMIC', or `DEFAULT').

   * The *Note `INFORMATION_SCHEMA.STATISTICS': statistics-table.
     table now has an `INDEX_COMMENT' column to indicate any comment
     string provided for the column. The *Note `SHOW INDEX':
     show-index. statement now displays an `Index_comment' column that
     provides the same information.

   * The `LOAD XML INFILE' statement was added. This statement makes it
     possible to read data directly from XML files into database
     tables. For more information, see *Note load-xml::.

Bugs fixed:

   * Use of the `latin2_czech_cs' collation caused a server crash.
     (Bug#29459 (http://bugs.mysql.com/29459))


File: manual.info,  Node: news-5-2-4,  Next: news-5-2-3,  Prev: news-5-2-5,  Up: news-5-2-x

C.2.2 Changes in MySQL 5.2.4 (Not released)
-------------------------------------------

This is a new Alpha development release, fixing recently discovered
bugs.

*Note*:

This Alpha release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Network_ (a commercial MySQL offering). For more
details please see
`http://www.mysql.com/products/enterprise/advisors.html'.

Functionality added or changed:

   * *Incompatible Change*: Added the `optimizer_use_mrr' system
     variable to enable control over whether Multi-Range Read
     optimization is used. This replaces the `multi_range_count' system
     variable, which has been removed.

   * The syntax for the *Note `LOCK TABLES': lock-tables.  statement
     has been extended to support transactional table locks that do not
     commit transactions automatically. Following `LOCK TABLES ... IN
     SHARE MODE' or `LOCK TABLES ... IN EXCLUSIVE MODE', you can access
     tables not mentioned in the *Note `LOCK TABLES': lock-tables.
     statement. You can now also issue these extended *Note `LOCK
     TABLES': lock-tables. statements many times in succession, adding
     additional tables to the locked set, and without unlocking any
     tables that were locked previously. When using *Note `LOCK
     TABLES': lock-tables. with `IN SHARE MODE' or `IN EXCLUSIVE MODE',
     tables are not unlocked until the transaction is committed.

     The behavior of *Note `LOCK TABLES': lock-tables. when not using
     `IN SHARE MODE' or `IN EXCLUSIVE MODE' remains unchanged.

   * A new SQL function, `WEIGHT_STRING()', returns the weight string
     for an input string. The weight string represents the sorting and
     comparison value of the input string.

   * Added the `optimizer_switch' system variable to enable control
     over individual optimizations.

   * The maximum length of table comments was extended from 60 to 2048
     characters. The maximum length of column comments was extended
     from 255 to 1024 characters. Index definitions now can include a
     comment of up to 1024 characters.

   * Parser performance was improved for identifier scanning and
     conversion of ASCII string literals.


File: manual.info,  Node: news-5-2-3,  Next: news-5-2-2,  Prev: news-5-2-4,  Up: news-5-2-x

C.2.3 Changes in MySQL 5.2.3 (15 February 2007)
-----------------------------------------------

Bugs fixed:

   * MySQL would crash with an assertion on startup during recovery
     referring to `tc.log'.  (Bug#26161 (http://bugs.mysql.com/26161))

   * A crash would occur when running *Note `UPDATE': update. within a
     loop inside a stored procedure.  (Bug#25537
     (http://bugs.mysql.com/25537))


File: manual.info,  Node: news-5-2-2,  Next: news-5-2-1,  Prev: news-5-2-3,  Up: news-5-2-x

C.2.4 Changes in MySQL 5.2.2 (Not released)
-------------------------------------------

Bugs fixed:

   * MySQL would fail with an assertion on startup.  (Bug#25835
     (http://bugs.mysql.com/25835))


File: manual.info,  Node: news-5-2-1,  Prev: news-5-2-2,  Up: news-5-2-x

C.2.5 Changes in MySQL 5.2.1 (Not released Alpha)
-------------------------------------------------

Functionality added or changed:

   * Performance improvements: thread bottlenecks have been reduced
     when a larger number of parallel auto-commit threads executed a
     trivial query in a hard loop.

Bugs fixed:

   * Falcon compound primary key problem.  (Bug#25828
     (http://bugs.mysql.com/25828))

   * Assertion when killing a `CREATE TABLE ...  SELECT' statement.
     (Bug#25565 (http://bugs.mysql.com/25565))

   * A *Note `DROP TABLE': drop-table. statement on a table created
     using `CREATE TABLE ... SELECT ...' crashed the server.
     (Bug#25564 (http://bugs.mysql.com/25564))

   * Crash if create index on nullable `utf8' column.  (Bug#25555
     (http://bugs.mysql.com/25555))

   * Between fails with Unicode field.  (Bug#24511
     (http://bugs.mysql.com/24511))


File: manual.info,  Node: mem-news,  Next: connector-odbc-news,  Prev: news-5-2-x,  Up: news

C.3 MySQL Enterprise Monitor Change History
===========================================

* Menu:

* mem-news-2-1-0::               Changes in MySQL Enterprise Monitor 2.1.0 (Not yet released)
* mem-news-2-0-5::               Changes in MySQL Enterprise Monitor 2.0.5 (18th March 2009)
* mem-news-2-0-4::               Changes in MySQL Enterprise Monitor 2.0.4 (5th February 2009)
* mem-news-2-0-3::               Changes in MySQL Enterprise Monitor 2.0.3 (23rd January 2009)
* mem-news-2-0-2::               Changes in MySQL Enterprise Monitor 2.0.2 (14th January 2009)
* mem-news-2-0-1::               Changes in MySQL Enterprise Monitor 2.0.1 (15th December 2008)
* mem-news-2-0-0::               Changes in MySQL Enterprise Monitor 2.0.0 (11th December 2008)

This appendix lists the changes to the MySQL Enterprise Monitor,
beginning with the most recent release. Each release section covers
added or changed functionality, bug fixes, and known issues, if
applicable. All bug fixes are referenced by bug number and include a
link to the bug database. Bugs are listed in order of resolution. To
find a bug quickly, search by bug number.


File: manual.info,  Node: mem-news-2-1-0,  Next: mem-news-2-0-5,  Prev: mem-news,  Up: mem-news

C.3.1 Changes in MySQL Enterprise Monitor 2.1.0 (Not yet released)
------------------------------------------------------------------

This section documents all changes and bug fixes that have been applied
since the release of MySQL Enterprise Monitor, version 2.0.3.

Functionality added or changed:

   * The agent should be able to run as a non-root user. However, the
     startup scripts always started it as root.

     The agent chassis now has a new option `--user' to drop privileges
     after being started as root. Note, this does not work when not
     started as superuser, nor on Windows.

     A new dialog box has also been added to the agent installer. The
     dialog has the following text: `The agent does not need to run
     with root user privileges. The agent will switch to the user
     account provided below when started by the root user.'

     The dialog also has a text field to allow the entry of the user
     account.

     A new parameter was also added to the `mysql-monitor-agent.ini'
     file. The parameter has the format `user=xxx', where xxx is the
     user account to be used.  (Bug#33778 (http://bugs.mysql.com/33778))

Bugs fixed:

   * The installer used to upgrade from version 1.3 corrupted passwords
     containing the `?' character.  (Bug#42452
     (http://bugs.mysql.com/42452))

   * Sun multi-core processors caused all cores to be reported on the
     meta information page.

     The larger T-series SPARC processors have 32+ cores. This caused
     the meta information page in the Dashboard to scroll as it
     reported each one.  (Bug#42355 (http://bugs.mysql.com/42355))

   * The username field for new users was populated by the last
     username used.

     When creating a new user for the second time in Dashboard, the
     previously created username appeared in the dialog.  (Bug#42314
     (http://bugs.mysql.com/42314))

   * The `my.cnf' file for the Enterprise Monitor internal database had
     the following configuration item:

          innodb_autoextend_increment = 50M

     This generated the error:

          16:36:23 [Warning] option 'innodb_autoextend_increment': unsigned value 52428800
          adjusted to 1000

     This variable is interpreted as being specified in MB, so 50M
     would be 50 TB. Such a high value results in the variable being
     adjusted to 1000 MB.

     The value in the configuration file should be:

          innodb_autoextend_increment = 50

     (Bug#42096 (http://bugs.mysql.com/42096))

   * A number of Advisor rules had advice text that had not been
     translated into Japanese. The Advisors that contained untranslated
     rules included Performance, Schema and Security.  (Bug#42067
     (http://bugs.mysql.com/42067))

   * After an error was generated due to an incorrect password while
     trying to create a new user, the following error was obtained when
     subsequently attempting to create a valid new user:

          U0002 You must log in to access the requested resource

     (Bug#41384 (http://bugs.mysql.com/41384))

   * SNMP trap messages were sending 127.0.0.1 as the IP address, and
     there was no feature to allow the user to configure the IP address
     contained in the SNMP message, which would have been useful for
     troubleshooting.  (Bug#41361 (http://bugs.mysql.com/41361))

   * Allowing the heat chart rules to be set to unscheduled caused the
     user interface to appear broken.  (Bug#41312
     (http://bugs.mysql.com/41312))

   * Graphs were incorrect for data that did not change. The graphs
     appeared as if no data had been gathered.

     The Hit Ratios graph had gaps in it where there had not been any
     activity on the parameters being monitored. For instance, if
     MyISAM tables were not used, then no Key Cache hit ratio series
     was plotted, even though the variables were still being collected.
     (Bug#41232 (http://bugs.mysql.com/41232))

   * When creating a new Database Administrator user in FireFox 2 the
     following error message was generated:

          U0002 You must log in to access the requested resource.

     This occurred in a new installation using the default
     administrator account. No Query Analysis permissions were given.
     However, the operation worked correctly using the Safari web
     browser.  (Bug#41032 (http://bugs.mysql.com/41032))

   * The `Manage Servers' page did not refresh in a manner consistent
     with other pages. This meant that changes to configuration made by
     others would not be reflected on the page.  Also, changes in the
     status of the servers were not displayed automatically.
     (Bug#40792 (http://bugs.mysql.com/40792))

   * If the `On Save send test trap' checkbox was checked when the
     `Save' button was clicked and the locale was set to Japanese, an
     error occurred. The orange error banner was displayed at the top
     of the page with the error message in Japanese.  (Bug#32069
     (http://bugs.mysql.com/32069))


File: manual.info,  Node: mem-news-2-0-5,  Next: mem-news-2-0-4,  Prev: mem-news-2-1-0,  Up: mem-news

C.3.2 Changes in MySQL Enterprise Monitor 2.0.5 (18th March 2009)
-----------------------------------------------------------------

This section documents all changes and bug fixes that have been applied
since the release of MySQL Enterprise Monitor, version 2.0.4.

Bugs fixed:

   * Calling the Agent with the option `--agent-run-os-tests' resulted
     in a crash. This happened on Linux x86-64 systems. The resultant
     stack trace was:

          (qa-merlin)
          2009-03-04 16:39:42: (critical) chassis.c:1097: could not raise RLIMIT_NOFILE to 8192,
          Invalid argument (22). Current limit still 1024.
          sigar-test-all.c.124 (test_sigar_pid_get):
            pid = 5188
          sigar-test-all.c.106 (test_sigar_mem_get):
          ...cut...
          sigar-test-all.c.427 (test_sigar_file_system_list_get): (items = 13)
          [0]
            fs.dirname = /
            fs.devname = /dev/mapper/vg00-root
            fs.typename = local
            fs.sys-type-name = ext3
            fs.type = 2
            fsusage.total = 15481840
            fsusage.free = 14116140
            fsusage.used = 1365700
            fsusage.avail = 13329708
            fsusage.files = 1966080
            fsusage.use_percent = 0.100000
          [0]
            diskusage.reads = 315302
            diskusage.writes = 6318240
            diskusage.write_bytes = 25879511040
            diskusage.read_bytes = 6561092608
            diskusage.queue = 47457530080206
          Segmentation fault

     On some systems no output was shown, other than the message
     `Segmentation fault'.  (Bug#43381 (http://bugs.mysql.com/43381))

   * Following a change in the replication configuration, MySQL
     Enterprise Monitor did not display the new topology correctly.
     (Bug#43240 (http://bugs.mysql.com/43240))

   * When a data collection became invalid, the agent sent NULLs for
     those collection values. However, the timestamps that it sent with
     the values were the timestamps from the last valid value that was
     collected.

     Due to key constraints on the Service Manager side, MySQL
     Enterprise Monitor disregarded anything sent with duplicate
     timestamps, thus the NULLs received from the agent were never
     processed. Some mechanisms, such as replication discovery, depend
     on the NULLs to identify a situation where data has become invalid.
     (Bug#43239 (http://bugs.mysql.com/43239))

   * MySQL Enterprise Monitor did not add a log entry each time data
     was purged. The log entry should have noted how many rows of each
     type of data were purged (historical data, logs, quan data).
     (Bug#43159 (http://bugs.mysql.com/43159))

   * The `Table Cache Set Too Low For Startup' and `Table Cache Not
     Optimal' rules were not supported on MySQL 5.1 because the
     `table_cache' system variable was deprecated and replaced with
     `table_open_cache'.  (Bug#42663 (http://bugs.mysql.com/42663))

   * Migrated server was not completely deleted.

     In a Monitor that had been updated from 1.3.2 to 2.0.4, with 2
     database servers queued for migration, if a server being migrated
     was deleted, or a migrated server was deleted, this would not be
     reflected in the user interface or in the license count, until
     Tomcat was restarted.  (Bug#42604 (http://bugs.mysql.com/42604))

   * The installer used to upgrade from version 1.3 corrupted passwords
     containing the `?' character.  (Bug#42452
     (http://bugs.mysql.com/42452))

   * Sun multi-core processors caused all cores to be reported on the
     meta information page.

     The larger T-series SPARC processors have 32+ cores. This caused
     the meta information page in the Dashboard to scroll as it
     reported each one.  (Bug#42355 (http://bugs.mysql.com/42355))

   * If an attempt was made to disable a rule using the link next to
     the rule, the following error message was generated:

          U0002 You must log in to access the requested resource. Go to login page.

     However, clicking on the link did not prompt the user to login
     again.  (Bug#42313 (http://bugs.mysql.com/42313))

   * Changing `ssh-agent' from OpenSSH or specifying a malevolent value
     of `agent-host-id', could inject data into the monitored MySQL
     Server.

     For example, setting `agent-host-id' to the value `I'm a test'
     would result in the following message in the error log:

          2009-01-23 15:45:11: ((error)) agent_mysqld.c:281: mysql_real_query('INSERT INTO
          mysql.inventory  (name, value) VALUES ( 'hostid', 'I'm a test' )') on 'mysql' failed: You
          have an error in your SQL syntax; check the manual that corresponds to your MySQL server
          version for the right syntax to use near 'm a test' )' at line 1 (mysql-errno = 1064)

     (Bug#42306 (http://bugs.mysql.com/42306))

   * When `SHOW GLOBAL STATUS' returned a value greater than 214748364,
     it was sent to the Service Manager as 214748364.  (Bug#42245
     (http://bugs.mysql.com/42245))

   * The Agent failed to identify local sockets as local on Mac OS X
     10.4.

     If the Agent was configured to use a Unix domain socket on Mac OS
     X 10.4, it did not treat the connection as local and failed to
     provide CPU and memory information to MySQL Enterprise Monitor.
     This is shown in the log file:

          2009-01-20 18:15:02: (message) network-socket.c:752: is-local family 0 != 1
          2009-01-20 18:15:02: (message) agent_mysqld.c:322: [mysql] mysqld is not local or not
          directly connected

     However, this problem did not happen on Mac OS X 10.5.  (Bug#42220
     (http://bugs.mysql.com/42220))

   * Some graphs on the `Graph' tab were not updated after the page was
     refreshed, or `Update' was clicked.

     The only way to get an updated graph was to change the graph size
     (in pixels) and then click `Update'.  (Bug#42162
     (http://bugs.mysql.com/42162))

   * The `my.cnf' file for the Enterprise Monitor internal database had
     the following configuration item:

          innodb_autoextend_increment = 50M

     This generated the error:

          16:36:23 [Warning] option 'innodb_autoextend_increment': unsigned value 52428800
          adjusted to 1000

     This variable is interpreted as being specified in MB, so 50M
     would be 50 TB. Such a high value results in the variable being
     adjusted to 1000 MB.

     The value in the configuration file should be:

          innodb_autoextend_increment = 50

     (Bug#42096 (http://bugs.mysql.com/42096))

   * A number of Advisor rules had advice text that had not been
     translated into Japanese. The Advisors that contained untranslated
     rules included Performance, Schema and Security.  (Bug#42067
     (http://bugs.mysql.com/42067))

   * The Service Manager did not handle the case where the agent failed
     to supply a valid `master_ip'. The Service Manager would then not
     restart. The logs contained the following:

          2009-01-09 14:39:50,472 ERROR [main:org.springframework.web.context.ContextLoader] Context
          initialization failed
          org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with
          name 'serverConnectionMonitor' defined in ServletContext resource
          [/WEB-INF/applicationContext.xml]: Unsatisfied dependency expressed through constructor
          argument with index 2 of type [com.mysql.etools.monitor.bo.Manager]: Error creating bean
          with name 'manager' defined in ServletContext resource [/WEB-INF/applicationContext.xml]:
          Invocation of init method failed; nested exception is
          com.mysql.etools.monitor.pom.UnsupportedAttributeException:
          101c6b5b-15eb-49aa-916c-843c51b28d38: mysql.slavestatus.Master_ip

     (Bug#42005 (http://bugs.mysql.com/42005))

   * Having too many users with strong privileges generated Service
     Manager errors and events failed to be triggered.

     If there were approximately 1000 users with full privileges and
     the value of `group_concat_max_len' was set to 100001, the size of
     the data that the agent sent to the Service Manager was too large
     and caused Service Manager errors. Also, the Security event
     `Account has Strong MySQL privileges' did not trigger.  (Bug#41987
     (http://bugs.mysql.com/41987))

   * Query Analyzer's Query Type filter for `SELECT' ignored statements
     starting with parenthesis.

     If you sent a statement through Query Analyzer starting with
     parenthesis, such as:

          (SELECT 1 FROM dual);

     and then attempted to filter for `SELECT' queries only, queries
     starting with parenthesis were not displayed.  (Bug#41968
     (http://bugs.mysql.com/41968))

   * The agent angel process was spawning too soon, which caused a
     duplicate UUID error.

     `g_error()' logged a fatal error, and called `abort()'. This
     terminated the program. Then the angel respawned with the same
     UUID, but with a -1 session resync request, which the MEM server
     denied because the old session was still active. This resulted in
     a permissions denied error (1142) on the `mysql.inventory table'.

          2008-12-17 18:58:58: (message) agent_mysqld.c:313: [mysql] mysqld is local and directly connected
          2008-12-17 18:58:58: ((error)) agent_mysqld.c:444: [mysql] mysql_real_query("SELECT value
          FROM mysql.inventory WHERE name = 'uuid'") failed: SELECT command denied to user
          'ent_agent'@'127.0.0.1' for table 'inventory' (errno=1142)
          2008-12-17 18:58:58: (debug) chassis.c:282: 15134 returned: 15134
          2008-12-17 18:58:58: (message) chassis.c:304: [angel] PID=15134 died on signal=6 (it used
          0 kBytes max) ... waiting 3min before restart
          2008-12-17 18:59:00: (debug) chassis.c:244: we are the child: 15149
          2008-12-17 18:59:00: (message) chassis.c:259: [angel] we try to keep PID=15149 alive
          2008-12-17 18:59:00: (debug) chassis.c:277: waiting for 15149
          2008-12-17 18:59:00: (message) mysql-proxy 0.7.0 started
          2008-12-17 18:59:00: (message) MySQL Monitor Agent 2.0.0.7111 started.

     (Bug#41600 (http://bugs.mysql.com/41600))

   * `master_uuid' discovery did not work with MySQL Server versions
     prior to 5.1. `master_uuid' did not show in any Agent to Monitor
     communications, and no log or error messages were generated.

     However, now the bug has been fixed, an Agent monitoring a 5.0
     MySQL Server would register the following in its logs:

          ...
           <classname>slavestatus</classname>
           <instance>12515cdc-8c00-4223-9d2a-2666a403512c</instance>
           <attribute>Master_uuid</attribute>
          </target>
          <utc>2009-03-03T19:58:05.700Z</utc>
          <value>b2fd9f86-6e42-49f2-b930-e8fb3e728179</value>

     Note the presence of `master_uuid'.  (Bug#41525
     (http://bugs.mysql.com/41525))

   * The `master_uuid' was not used for replication topology discovery.

     The agent collected `master_uuid' by reading the `master.info'
     file, and then running a `SELECT' directly against its master.
     This was to try and read the `mysql.inventory' table on the master
     to obtain the instance `master_uuid'.

     However, this was not being used correctly by the replication
     topology discovery within the server.  (Bug#41519
     (http://bugs.mysql.com/41519))

   * After an error was generated due to an incorrect password while
     trying to create a new user, the following error was obtained when
     subsequently attempting to create a valid new user:

          U0002 You must log in to access the requested resource

     (Bug#41384 (http://bugs.mysql.com/41384))

   * Agent startup failed on Solaris 10. The error generated was:

          # ./mysql-monitor-agent start
          Bad string
          ERROR! /opt/mysql/enterprise/agent/etc/mysql-monitor-agent.ini has to have a
          [mysql-proxy].pid-file setting

     This was caused by unexpected behavior of the `tr' command.
     (Bug#41260 (http://bugs.mysql.com/41260))

   * On the Query Analysis page, if a query was clicked the minimum
     displayed was greater than the average.  (Bug#41259
     (http://bugs.mysql.com/41259))

   * In some circumstances the agent/proxy ran out of file descriptors,
     causing secondary failures. It could not recover from that state.
     The relevant part of the log file is shown here:

          2008-11-27 11:11:00: (critical) last message repeated 2 times
          2008-11-27 11:11:00: (critical) job_collect_os.c:411: sigar_cpu_info_list_get() failed
          2008-11-27 11:11:00: (critical) job_collect_os.c:445: sigar_cpu_list_get() failed
          2008-11-27 11:11:00: (critical) job_collect_os.c:411: sigar_cpu_info_list_get() failed
          2008-11-27 11:11:00: (critical) job_collect_os.c:445: sigar_cpu_list_get() failed
          2008-11-27 11:11:00: (critical) job_collect_os.c:411: sigar_cpu_info_list_get() failed
          2008-11-27 11:11:00: (critical) job_collect_os.c:445: sigar_cpu_list_get() failed
          2008-11-27 11:11:00: (critical) job_collect_os.c:411: sigar_cpu_info_list_get() failed
          2008-11-27 11:11:00: (critical) job_collect_os.c:445: sigar_cpu_list_get() failed
          2008-11-27 11:11:30: (critical) network-socket.c.292: socket(127.0.0.1:3306) failed: Too many open files (24)
          2008-11-27 11:11:30: (critical) proxy-plugin.c.1532: Cannot connect, all backends are down.
          2008-11-27 11:20:22: (critical) last message repeated 4 times
          2008-11-27 11:20:22: (critical) network-io.c:215:
          curl_easy_perform('https://user:password@merlin-dashboard:443/heartbeat') failed:
          SSL connection timeout (curl-error = 'Timeout was reached' (28), os-error = 'Connection refused' (111))

     (Bug#41068 (http://bugs.mysql.com/41068))

   * If an installation of Service Manager 2.0.0.7102 included a
     `backup' directory, due to a previous upgrade, and was upgraded
     using at least Service Manager 2.0.0.7103, then the installer
     displayed an error message and exited.

     The error message displayed was:

          There has been an error.
          Error renaming /Applications/mysql/enterprise/monitor/apache-tomcat to
          /Applications/mysql/enterprise/monitor/backup/apache-tomcat
          The application will exit now

     (Bug#40996 (http://bugs.mysql.com/40996))

   * The Agent started without problems and connected to the master.
     But it was unable to perform a `SELECT' from the table
     `mysql.inventory' in order to obtain server information.
     (Bug#40933 (http://bugs.mysql.com/40933))

   * The startup scripts supplied with MySQL Network Monitoring and
     Advisory tool did not supply all of the LSB `init.d' script
     options required. A list of the required options can be found at
     the following website
     `http://refspecs.freestandards.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html'

     The required options missing include `status' and `force-reload'.
     The option `status' is used by monitoring tools and cluster
     software such as Red Hat Cluster, to ensure that the service is
     still running. The `force-reload' option is an alias for restart.
     (Bug#29848 (http://bugs.mysql.com/29848))


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C.3.3 Changes in MySQL Enterprise Monitor 2.0.4 (5th February 2009)
-------------------------------------------------------------------

This section documents all changes and bug fixes that have been applied
since the release of MySQL Enterprise Monitor, version 2.0.3.

Bugs fixed:

   * The Service Agent did not log connections to, and disconnects
     from, the monitored database.

     This meant it was not possible to check if the Agent was connected
     to the database by simply looking at the log file.  (Bug#42403
     (http://bugs.mysql.com/42403))

   * The Service Agent failed to create the `mysql.inventory' table.
     The logs displayed the following error message:

          (critical) (share/mysql-proxy/quan.lua:711) [proxy] please add SELECT permissions for
          this user on mysql.inventory to enable the QUAN feature, got Table 'mysql.inventory'
          doesn't exist

     This happened even though the Service Agent used the `root'
     account.  (Bug#42389 (http://bugs.mysql.com/42389))

   * After installing Service Agent 2.0.4.7138 and then starting it
     with `--version', the incorrect version was displayed. Although
     2.0.4.7138 was installed, the Service Agent displayed the version
     number as 2.0.2.7138.  (Bug#42263 (http://bugs.mysql.com/42263))

   * An invalid path was shown in the error message if the upgrade
     installer failed to find the previous install location.

     The error message is shown below, note that the error message
     displays a different path to that provided by the user:

          Please specify the directory that contains the previous installation of the MySQL
          Enterprise Monitor Agent

          Installation directory [/home/mysql/mysql/enterprise/agent]: /var/lib/mysql/agent

          Warning: The directory /home/mysql/mysql/enterprise/agent does not contain a a
          previous installation. Please select the right installation directory.
          Press [Enter] to continue :
          ----------------------------------------------------------------------------
          Please specify the directory that contains the previous installation of the MySQL
          Enterprise Monitor Agent

     (Bug#42200 (http://bugs.mysql.com/42200))

   * The agent password error in the Service Manager did not log the
     originating host, making it impossible to determine the agent that
     failed to log in:

          ErrorJan 5, 2009 4:56:08 PM<?xml version='1.0'?><exceptions><error><![CDATA[E1702:
          IncorrectPasswordException: [agent]]]></error></exceptions>

     (Bug#42139 (http://bugs.mysql.com/42139))

   * The Service Manager's JDBC connections did not have `sql_mode' set
     to include `NO_ENGINE_SUBSTITUTION'. This resulted in the failure
     of Data Definition Language (DDL) if the Service Manager was
     inadvertently pointed to an incorrect `mysqld' instance.
     (Bug#42137 (http://bugs.mysql.com/42137))

   * A number of Advisor rules had advice text that had not been
     translated into Japanese. The Advisors that contained untranslated
     rules included Performance, Schema and Security.  (Bug#42067
     (http://bugs.mysql.com/42067))

   * Service Agent configuration files had global read privileges on
     the filesystem.  (Bug#41794 (http://bugs.mysql.com/41794))

   * When the log files rotated to the maximum allowed by the `log4j'
     configuration, the metadata contained in the `FileAppender' became
     out of synchronization due to a logic bug. This caused an assertion
     error on any subsequent request for the logs tab or data.
     (Bug#41593 (http://bugs.mysql.com/41593))

   * SNMP trap messages were sending 127.0.0.1 as the IP address, and
     there was no feature to allow the user to configure the IP address
     contained in the SNMP message, which would have been useful for
     troubleshooting.  (Bug#41361 (http://bugs.mysql.com/41361))

   * Although the `Monitor' tab loaded initially, after a 64-bit MySQL
     server running a 32-bit MySQL Monitor Agent was clicked, a Null
     Pointer Exception was generated.  (Bug#41164
     (http://bugs.mysql.com/41164))

   * The Service Agent startup configuration did not seem to work and
     did not generate a log file.  (Bug#40583
     (http://bugs.mysql.com/40583))

   * An error generated by a rule failed to clear.

     When a rule was created with the `os:disk:fs_used' data item, if
     the instance was not a valid mount point then the Service Agent
     reported the error:

          2008-08-11 17:57:00: (critical) disk-get failed for all: 2

     Note the above instance was for `all', and similar results
     occurred for instance `disk'.

     The issue was that upon editing the rule, or even deleting the
     rule, the agent still showed the above error type. Restarting the
     agent and the monitoring service failed to remove the error.
     (Bug#38709 (http://bugs.mysql.com/38709))

   * If the `On Save send test trap' checkbox was checked when the
     `Save' button was clicked and the locale was set to Japanese, an
     error occurred. The orange error banner was displayed at the top
     of the page with the error message in Japanese.  (Bug#32069
     (http://bugs.mysql.com/32069))


File: manual.info,  Node: mem-news-2-0-3,  Next: mem-news-2-0-2,  Prev: mem-news-2-0-4,  Up: mem-news

C.3.4 Changes in MySQL Enterprise Monitor 2.0.3 (23rd January 2009)
-------------------------------------------------------------------

This section documents all changes and bug fixes that have been applied
since the release of MySQL Enterprise Monitor, version 2.0.2.

Bugs fixed:

   * The Service Agent failed to connect to the server, and no error
     message was displayed in the log file.

     However, when the log verbosity level was set to `message', the
     following message was recorded:

          2009-01-12 13:34:43: (warning) agent_mysqld.c:600: agent connecting to mysql-server
          failed: mysql_real_connect(host = '127.0.0.1', port = 3306, socket = ''): Lost connection
          to MySQL server at 'reading initial communication packet', system error: 0 (mysql-errno =
          2013)

     (Bug#42044 (http://bugs.mysql.com/42044))

   * There was a mismatch between the contents of an SNMP Trap from
     MySQL Enterprise Monitor and the definition given in the file
     `MONITOR.MIB'.  (Bug#41912 (http://bugs.mysql.com/41912))

   * If a copy was made of a standard rule, the resulting Wiki markup
     was incorrect, resulting in the display of user-interface text
     containing HTML markup.  (Bug#41375 (http://bugs.mysql.com/41375))

   * Allowing the heat chart rules to be set to unscheduled caused the
     user interface to appear broken.  (Bug#41312
     (http://bugs.mysql.com/41312))

   * When a custom rule requiring disk information was created, for
     example:

          [Expression]
          %disk_reads% > THRESHOLD

          [Thresholds]
          Critical Alert: 9000
          Warning Alert: 3000
          Info Alert: 1000

          [Variable Assignment]
          variables: %disk_reads%
          Data Item: os:disk:disk_reads
          Instance: /

     The following error was written to the file
     `mysql-service-agent.log':

          2007-09-05 17:11:00: (critical) disk-get failed for c0d0p1: 2

     It therefore appeared that the Service Agent was not able to
     obtain the required information.  (Bug#30820
     (http://bugs.mysql.com/30820))


File: manual.info,  Node: mem-news-2-0-2,  Next: mem-news-2-0-1,  Prev: mem-news-2-0-3,  Up: mem-news

C.3.5 Changes in MySQL Enterprise Monitor 2.0.2 (14th January 2009)
-------------------------------------------------------------------

This section documents all changes and bug fixes that have been applied
since the release of MySQL Enterprise Monitor, version 2.0.1.

Bugs fixed:

   * The `Complete Setup' button was missing from the `Setup' page you
     were taken to after the current subscription expired.  (Bug#41685
     (http://bugs.mysql.com/41685))

   * If the `host-id' of the monitored instance and the `host-id' of
     the current agent did not match, the agent generated the following
     error message:

          Please TRUNCATE TABLE mysql.inventory on this mysql-instance and restart the agent.

     However, it did not suggest using `sql_log_bin = 0'. This is used
     for all other actions against this table so that they are not
     replicated to slaves, each of which has their own copy of this
     table.  (Bug#41673 (http://bugs.mysql.com/41673))

   * The Agent did not start up when the monitored server had many
     databases and tables, and was under heavy load. This was because
     the `trigger_schema' query was taking too long on agent start up.
     (Bug#41555 (http://bugs.mysql.com/41555))

   * The Service Agent failed to install on Solaris 10 x86. The
     following error was generated:

          Installing
          0% ______________ 50% ______________ 100%
          ########################################
          Warning: Problem running post-install step.
          Installation may not complete correctly
          Error running /usr/local/mysqlagent/bin/mysql-monitor-agent
          --defaults-file=/usr/local/mysqlagent/etc/mysql-monitor-agent.ini
          --plugins=agent --agent-generate-uuid=true : 2008-12-12 13:06:02: (critical)
          Conversion from character set '646' to 'UTF-8' is not supported
          2008-12-12 13:06:02: (message) shutting down normally

     (Bug#41445 (http://bugs.mysql.com/41445))

   * The console/stdout appender remained in the log4j configuration,
     which meant that all the MySQL Enterprise Monitor server logs were
     duplicated to Catalina's stdout, and thus `catalina.out', which
     was wasteful, especially as that file was not rotated or managed.
     (Bug#41439 (http://bugs.mysql.com/41439))

   * When creating new multiple user accounts, the first attempt worked
     fine. However, following attempts to create new users did not show
     the `Query Analyzer Options' in the `Create User' popup until the
     role field was changed.  (Bug#41430 (http://bugs.mysql.com/41430))

   * When login privileges were required the Service Manager did not
     redirect the user to the login page. This resulted in error
     messages being displayed rather than simply redirecting the user
     to the login page. This problem typically occurred if it was
     necessary to restart Tomcat.  (Bug#41320
     (http://bugs.mysql.com/41320))

   * The monitor 2.0.0.7105 and 2.0.0.7122 Solaris Intel update
     installer quits unexpectedly. The installer exits from the GUI in
     the `Backup of Previous Installation' screen, when OpenSolaris is
     running on top of Sun xVM.

     The console output for both installer versions is given below:

          shell> ./mysqlmonitor-2.0.0.7105-solaris-intel-update-installer.bin
          X Error of failed request:  BadMatch (invalid parameter attributes)
            Major opcode of failed request:  73 (X_GetImage)
            Serial number of failed request:  21161
            Current serial number in output stream:  21161

          shell> ./mysqlmonitor-2.0.0.7122-solaris-intel-update-installer.bin
          X Error of failed request:  BadMatch (invalid parameter attributes)
            Major opcode of failed request:  73 (X_GetImage)
            Serial number of failed request:  21148
            Current serial number in output stream:  21148

     (Bug#41315 (http://bugs.mysql.com/41315))

   * The `Rename Group' function failed if the new group name was
     different to the current one only in the case used; for example,
     if `Merlin' was changed to `MERLIN'.

     The error generated was:

          U0105 This group name is already in use. Enter a different name.

     (Bug#41266 (http://bugs.mysql.com/41266))

   * The Agent returned an inventory list of all databases and tables.
     This information was not used by MySQL Enterprise Monitor, other
     than to populate the `inv_databases' and `inv_tables' tables. For
     large-scale deployments, where there were many databases and
     tables, this resulted in redundant XML messages being sent from
     the Agent to the Service Manager.  (Bug#33150
     (http://bugs.mysql.com/33150))


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C.3.6 Changes in MySQL Enterprise Monitor 2.0.1 (15th December 2008)
--------------------------------------------------------------------

This section documents all changes and bug fixes that have been applied
since the release of MySQL Enterprise Monitor, version 2.0.0.

Bugs fixed:

   * Having an installation with over 420 master binlogs resulted in
     the `mysql::status' graph not being plotted.  (Bug#41314
     (http://bugs.mysql.com/41314))

   * The MySQL Enterprise Monitor installer generated a segfault on
     RedHat Fedora 10:

          shell> ./mysqlmonitor-2.0.0.7105-linux-x86-installer.bin
          Segmentation fault

     (Bug#41196 (http://bugs.mysql.com/41196))


File: manual.info,  Node: mem-news-2-0-0,  Prev: mem-news-2-0-1,  Up: mem-news

C.3.7 Changes in MySQL Enterprise Monitor 2.0.0 (11th December 2008)
--------------------------------------------------------------------

This section documents all changes and bug fixes that have been applied
since the release of MySQL Enterprise Monitor, version 1.3.3.

Functionality added or changed:

   * *Important Change*: The `server-name' configuration parameter is
     deprecated. For compatibility, during an upgrade, the information
     will be migrated to a `displayname' configuration parameter within
     the individual instance configuration files. This configuration
     parameter is provided only for compatibility, as display name
     information is now stored within the main repository. Support for
     `displayname' is also deprecated and will be removed in a future
     release.

   * *Important Note*: The rules `32-Bit Binary Running on 64-Bit AMD
     Or Intel System' and `Key Buffer Size Greater Than 4 GB'
     occasionally do not evaluate correctly due to timing issues. This
     causes them to be displayed with the `Severity' level of `Unknown'.
     This is a known issue and will be resolved in future versions of
     MySQL Enterprise Monitor.

   * *Important Note*: When you start the Merlin 2.0 agent from the
     command line on Windows, you get the following error dialog:

          "mysql-proxy.exe - Entry Point Not Found"
          "The procedure entry point libiconv_set_relocation_prefix could not be located in the
          dynamic link library iconv.dll"

     If you click `OK' the agent works fine after that.

     This only occurs when starting the agent from the command line,
     and only when there is another version of one of the DLLs that the
     agent uses somewhere on the current path. This error can be
     avoided by opening a command prompt, typing `SET PATH=' to clear
     the path, and then starting the agent.

   * *Important Note*: If you are monitoring one instance of MySQL
     server (mysqld) and then upgrade that MySQL server, the correct
     version of the MySQL server is not displayed in the Dashboard.
     This is a known issue that will be fixed in future versions of
     MySQL Enterprise Monitor.

   * The following has been added to the Tomcat `config.properties'
     properties file:

               # max connections in the pool for the repository
               default.maxActive=70

     (Bug#40652 (http://bugs.mysql.com/40652))

   * The dashboard could be used to change the agent password to one
     containing the `@' character, or other special characters, which
     subsequently caused errors. To fix this problem, special
     characters in passwords are now prevented by the dashboard. The
     list of disallowed special characters can be found at the
     following location:
     `http://en.wikipedia.org/wiki/Percent-encoding#Types_of_URI_characters'
     (Bug#37172 (http://bugs.mysql.com/37172))

   * The `Query Analysis' page was missing the `Refresh' dropdown
     control that the `Monitor', `Events', and `Graphs' pages had at
     the top.  (Bug#36831 (http://bugs.mysql.com/36831))

   * The User Interface only returned error strings, without any
     associated error codes. This meant that if the error string was in
     a language that the user did not understand, it would be very
     difficult to determine which error actually occurred.

     The User Interface now supports error codes, as well as error
     strings. This change allows easier testing of multiple locales.
     (Bug#32131 (http://bugs.mysql.com/32131))

   * The wording was changed on the fading popup subscription alert.
     The text `account' was changed to `subscription'.  (Bug#31492
     (http://bugs.mysql.com/31492))

   * The alert thresholds for the Query Cache Advisor were changed:

                       Information       Warning           Critical
     From              95                85                75
     To                60                50                40

     (Bug#30969 (http://bugs.mysql.com/30969))

   * The agent log file name has changed from `mysql-service-agent.log'
     to `mysql-monitor-agent.log'. The old log file will be retained
     during a upgrade install.

Bugs fixed:

   * Starting a new agent against an instance that contained many
     databases broke up the initial discovery packet, causing
     collections such as CPU usage and their graphs to fail. See also
     Bug#33150 (http://bugs.mysql.com/33150) and Bug#41314
     (http://bugs.mysql.com/41314).  (Bug#41933
     (http://bugs.mysql.com/41933))

   * When altering an existing rule you had to add an empty string,
     `""', to any threshold level that was empty.  Otherwise, the rule
     failed to run and the resulting exceptions caused the `Events'
     page to be unusable due to duplicate key exceptions.  (Bug#41310
     (http://bugs.mysql.com/41310))

   * After installing the 2.0.0.7119 Dashboard the following error was
     generated in the logs:

          com.opensymphony.xwork2.util.OgnlValueStack  Warning  Dec 5, 2008 10:41:26 AM  Caught
          an Ognl exception while getting property titleAddition

     (Bug#41252 (http://bugs.mysql.com/41252))

   * The `dc_ng_long_now' table became very large partly due to an
     unused column `begin_time'.  (Bug#41093
     (http://bugs.mysql.com/41093))

   * Although there was a unique constraint on the user name, it was
     not enforced during first-time setup. This resulted in a stack
     trace being produced, rather than a more user-friendly error
     message, if the same name was used for the `admin' and `agent'
     accounts.  (Bug#40870 (http://bugs.mysql.com/40870))

   * MySQL Enterprise Monitor server had stopped sending up/down SNMP
     traps.  (Bug#40861 (http://bugs.mysql.com/40861))

   * The Query Analyzer's `Explain Query' tab did not have pop up text
     or a link to the documentation regarding `SELECT' queries.
     (Bug#40841 (http://bugs.mysql.com/40841))

   * When you tried to import a Trial-level advisor JAR using a Trial
     user account, one of the following error messages was generated:

          U0009 The uploaded Advisor jar was invalid

          U0161 Please import a Platinum level Advisor .jar to use with this Platinum level product key

     (Bug#40834 (http://bugs.mysql.com/40834))

   * Meta Info on the Dashboard did not display information for the
     meta data `os_description'.  (Bug#40830
     (http://bugs.mysql.com/40830))

   * Attempting to create an alias of statements such as `COMMIT',
     `ROLLBACK', `BEGIN', resulted in the error:

          Can't find template commitTnx.st; group hierarchy is [HTMLFormatting]
          org.antlr.stringtemplate.StringTemplateGroup.lookupTemplate(StringTemplateGroup.java:507)

     (Bug#40736 (http://bugs.mysql.com/40736))

   * Trying to upgrade from 2.0.0.7088 to 2.0.0.7092 failed as there
     was a missing file. When the update program
     `mysqlmonitor-2.0.0.7092-solaris-intel-update-installer.bin' was
     run, the file `/tmp/com/mysql/merlin/server/version.props' could
     not be found.  (Bug#40692 (http://bugs.mysql.com/40692))

   * On OS X with Java 1.5, Tomcat crashed on launch with the error:

          Invalid memory access of location 00000007 eip=013df179

     (Bug#40689 (http://bugs.mysql.com/40689))

   * When the agent was installed using the command line installer and
     `--enableproxy 0' was specified, the installer should have removed
     `quan.lua' from the `agent-item-files' option in the INI file.
     (Bug#40551 (http://bugs.mysql.com/40551))

   * The Agent could not connect to a database with the `hostname' set
     to `localhost'.  Doing so resulted in the error:

          (critical) the MySQL server could not be reached at socket '(null)', we will check in 10 seconds

     (Bug#40530 (http://bugs.mysql.com/40530))

   * The update installer for the 2.0 Monitor did not have an `Is SSL
     support required?' checkbox.  Therefore, the appropriate SSL
     connector definition was commented out in the `conf/server.xml'
     file.  (Bug#40414 (http://bugs.mysql.com/40414))

   * The Service Manager installer did not uninstall or wipe out the
     previous installation if you answered `Yes' to the question:

     `The directory you selected already contains a MySQL installation.
     If you continue installation all data will be lost. Do you wish to
     continue?' (Bug#40410 (http://bugs.mysql.com/40410))

   * If you unchecked the `Enable Proxy' checkbox on the `Query
     Analysis Configuration' screen, the agent's INI file still
     contained proxy configuration data and was not commented out.
     (Bug#40272 (http://bugs.mysql.com/40272))

   * As different queries were sent through the agent it used
     increasing amounts of memory.  (Bug#40260
     (http://bugs.mysql.com/40260))

   * The Service Manager installer set the Java Virtual Machine option
     `HeapDumpPath' to `<install_root>\temp' on Windows and `/tmp' on
     other platforms. For consistency the `HeapDumpPath' directory
     should have been set to `<install_root>\tmp' on Windows.
     (Bug#40215 (http://bugs.mysql.com/40215))

   * When using the command line agent setup program, a socket file was
     not accepted for the monitored instance.  (Bug#40085
     (http://bugs.mysql.com/40085))

   * The language option when installing the MySQL Enterprise Monitor
     in Japanese using the command-line instllaer has been changed from
     `jp' to `ja'.  (Bug#40082 (http://bugs.mysql.com/40082))

   * When monitoring MySQL 5.1.24 and above, the user used by the agent
     to connect to the MySQL server for monitoring must have the
     `PROCESS' privilege.  (Bug#40050 (http://bugs.mysql.com/40050))

   * The check box option string `Is SSL support required?', on the
     Tomcat Server Option dialog of the Monitor installation, was not
     correctly translated into Japanese.  (Bug#39814
     (http://bugs.mysql.com/39814))

   * The base application directory for the MySQL Enterprise Dashboard
     has been updated from `http://localhost:18080/merlin' to
     `http://localhost:18080/'.  (Bug#39403
     (http://bugs.mysql.com/39403))

   * If the Service Manager or the MySQL Server running the Repository
     crashed, they did not restart automatically.  (Bug#39377
     (http://bugs.mysql.com/39377))

   * If the agent crashed, there was no watchdog, angel or keep-alive
     mechanism to restart the agent and keep it running.  (Bug#39374
     (http://bugs.mysql.com/39374))

   * If the MySQL client libraries were located in a non-standard
     location, the agent 2.0.0.7042 installer failed with a `library
     not found' error.  (Bug#39317 (http://bugs.mysql.com/39317))

   * For the rule `Server-Enforced Data Integrity Checking Not Strict',
     the Recommended Action did not display correctly. It displayed as
     `SET sql_mode=modes', rather than `SET [GLOBAL|SESSION]
     sql_mode=modes'.  (Bug#39261 (http://bugs.mysql.com/39261))

   * A query that was issued through the proxy, and that had an
     auto-explain performed on that query, did not give the correct
     response to a subsequent query of `SELECT FOUND_ROWS()'.
     (Bug#39223 (http://bugs.mysql.com/39223))

   * It was not possible to establish a connection with the Dashboard
     using the SSL protocol (https://).  (Bug#39198
     (http://bugs.mysql.com/39198))

   * When a 1.3 MySQL Enterprise Monitor installation with many rules
     scheduled was upgraded to 2.0, the upgraded installation was then
     found to have only the heat chart rules scheduled.  (Bug#39043
     (http://bugs.mysql.com/39043))

   * The agent installer did not allow a second agent to be installed
     on Windows.  (Bug#38976 (http://bugs.mysql.com/38976))

   * The Dashboard incorrectly diplayed that insufficient licenses were
     available, even though sufficient licenses had been purchased.
     (Bug#38514 (http://bugs.mysql.com/38514))

   * After running the MySQL Service Agent uninstall program, the file
     `/etc/init.d/mysql-service-agent' remained present on the server.
     (Bug#38490 (http://bugs.mysql.com/38490))

   * The notice fader continued to display English text after you
     changed the locale to Japanese.  (Bug#38460
     (http://bugs.mysql.com/38460))

   * The `Subscription Expired' pop-up window referred to the `Global
     Preferences' page, instead of the `Global Settings' page.
     (Bug#38358 (http://bugs.mysql.com/38358))

   * An inappropriate time zone was used to parse user-entered date and
     time strings.  (Bug#38323 (http://bugs.mysql.com/38323))

   * A sigar network stats error was generated on the Solaris platform:

          # /opt/mysql/enterprise/agent/bin/mysql-service-agent --version
          MySQL Service Agent - 1.2.0.7879, (glib lib=2.8.5, headers=2.8.5)

          SunOS mysqlprd01 5.10 Generic_127127-11 sun4v sparc SUNW,T5240

          2008-07-21 10:07:24: (critical) sigar_net_interface_config_primary_get() failed: 6
          2008-07-21 10:08:00: (critical) sigar_net_interface_config_primary_get() failed: 6

          # /opt/mysql/enterprise/agent/bin/sigar-test-all >/tmp/test.txt
          sigar_net_interface_stat_get(e1000g0:2) failed#

     (Bug#38302 (http://bugs.mysql.com/38302))

   * After deleting a server from the `Settings', `Manage Servers' tab,
     at the very bottom of the page the `Monitoring x instances on x
     host' values did not reflect the deletion.  (Bug#38225
     (http://bugs.mysql.com/38225))

   * The MySQL Enterprise Monitor alert `INFO Alert - Users Can View
     All Databases On MySQL Server (v 1.5 *)' from the Security advisor
     was incorrect. This is because the default server behavior allows
     users to see databases for which they have privileges, not `all
     databases on server' as suggested by the alert.  (Bug#38052
     (http://bugs.mysql.com/38052))

   * The `Maximum Connection Limit Nearing Or Reached' advisor did not
     generate a new Critical Alert event when there was an open info
     success event.  (Bug#37816 (http://bugs.mysql.com/37816))

   * The Linux IA64 installer appeared to crash. The installer appeared
     to crash on RH4_IA64 if called with option "-version":

          -------------------------------------------------------------------------------
          <INSTALLER> --version
          mysqlmonitorage(30704): unaligned access to 0x6000000000a8413c, ip=0x2000000003ddd5f0
          mysqlmonitorage(30704): unaligned access to 0x6000000000a84144, ip=0x2000000003ddd5f1
          mysqlmonitorage(30704): unaligned access to 0x6000000000a8414c, ip=0x2000000003ddd600
          mysqlmonitorage(30704): unaligned access to 0x6000000000a84154, ip=0x2000000003ddd601
          MySQL Enterprise Monitor Agent 0.7.0.1737 --- Built on 2008-06-25 19:31:53

          -------------------------------------------------------------------------------

     However, this warning is harmless and will not impact the
     operation of the agent.  (Bug#37496 (http://bugs.mysql.com/37496))

   * If the log-level option in the agent configuration file was set to
     an unknown level by mistake, the `init.d' script appeared to enter
     an infinite loop.  (Bug#37108 (http://bugs.mysql.com/37108))

   * Malformatted server meta information appeared on the Dashboard;
     `RAM' and `Disk Space' appeared under the `CPU' category.
     (Bug#36740 (http://bugs.mysql.com/36740))

   * A `rename' link incorrectly appeared next to the `Upgrade'
     category on the `Manage Rules' page.  (Bug#36584
     (http://bugs.mysql.com/36584))

   * In the case where exceptions were passed through to the User
     Interface, the substituted arguments in the message contained
     developer-only information.  (Bug#36580
     (http://bugs.mysql.com/36580))

   * `Agent Version', `Last MySQL Contact', `OS Info', `CPU Info', and
     `IP Addresses' were all blank on the dashboard when the agent for
     the selected server was not functioning.  (Bug#36301
     (http://bugs.mysql.com/36301))

   * `mysql-monitor-agent' became confused by the `.DS_Store' files
     that are created on Mac OS X.  (Bug#36216
     (http://bugs.mysql.com/36216))

   * The rule `Key Buffer Size Greater Than 4 GB' incorrectly triggered
     the following alert:

     `CRITICAL Alert - Key Buffer Size Greater Than 4 GB'

     However, on non-Windows systems, a key buffer size greater than 4
     GB is supported.  (Bug#36143 (http://bugs.mysql.com/36143))

   * Since the repository database for MySQL Enterprise Monitor uses
     InnoDB there was no way to reduce the size of the data files after
     an old log/event data purge operation. Further, the purge data
     operation executed once per day, and had no option to trigger the
     purge operation manually.  (Bug#35971
     (http://bugs.mysql.com/35971))

   * On the Graphs page, if all graphs were expanded, then the Time
     Display interval updated, the page was refreshed with the `Expand
     All' button displayed, even though all the graphs were already
     expanded.  (Bug#35917 (http://bugs.mysql.com/35917), Bug#35133
     (http://bugs.mysql.com/35133))

   * The Meta Info area of the Monitor page incorrectly reported the
     operating system version number for the MySQL version.  (Bug#35836
     (http://bugs.mysql.com/35836))

   * The rule `XA Distributed Transaction Support Enabled For InnoDB'
     incorrectly sent a warning when the binary log was on.  (Bug#35786
     (http://bugs.mysql.com/35786))

   * On the Monitor page, the time displayed for `Last MySQL Contact'
     lagged behind that for `Last Agent Contact' by a large amount.
     (Bug#35774 (http://bugs.mysql.com/35774))

   * MySQL Enterprise Monitor did not update replication settings
     correctly. After a slave became the master, the Adviser still
     referred to it as a slave.  (Bug#35771
     (http://bugs.mysql.com/35771))

   * The Adviser email suggested using the
     `--log-queries-not-using-indexes' option.  However, this option is
     not available in MySQL Server versions prior to 4.1.  (Bug#35770
     (http://bugs.mysql.com/35770))

   * Thumbnail graphs did not update properly after a time zone change.
     (Bug#35756 (http://bugs.mysql.com/35756))

   * If a system had a global `wait_timeout' lower than the general
     activity of the agent, the agent was disconnected. The monitored
     server then logged an error and incremented `Aborted_clients'.
     (Bug#35648 (http://bugs.mysql.com/35648))

   * Alerts fired after a blackout period based on data collections
     that happened during the blackout.  (Bug#35617
     (http://bugs.mysql.com/35617))

   * The translation of the `Add Row' button on the Rule Definition
     window was incorrect.  (Bug#35495 (http://bugs.mysql.com/35495))

   * An uninstallation message asked about removing Apache files, even
     though Apache is no longer used.  (Bug#35154
     (http://bugs.mysql.com/35154))

   * After updating from a previous version to the latest 1.3 version,
     the `Query Cache Has Sub-Optimal Hit Rate' was still displayed in
     English after setting the locale to Japanese. Note, the rule was
     translated correctly if the full installer was used.  (Bug#35134
     (http://bugs.mysql.com/35134))

   * The MySQL Enterprise Monitor uninstall dialog box had missing text
     when using the Japanese locale.  (Bug#34982
     (http://bugs.mysql.com/34982))

   * Running the installer with the `--help' option caused an incorrect
     message to be displayed.  (Bug#34200 (http://bugs.mysql.com/34200))

   * When using the unattended `unInstall' script on Linux together
     with the option `--env deleteUserData=yes' the correct warning
     text was displayed. However, this text should not be displayed in
     unattended mode. Further, the option `--env deleteUserData=yes'
     was not displayed by the `--help' output.  (Bug#34071
     (http://bugs.mysql.com/34071))

   * Platinum Unlimited customers sometimes received a warning stating
     incorrectly that their subscription supported zero hosts.
     (Bug#34010 (http://bugs.mysql.com/34010))

   * Clicking on the resolution notes link for a closed event on the
     events tab showed incorrect behaviour. The popup initially showed
     the resolution notes, but when the resolution tab was clicked the
     notes disappeared and were replaced by an edit box.  (Bug#33935
     (http://bugs.mysql.com/33935))

   * The status on the product information page was not translated when
     the user locale was set to Japanese.  (Bug#32785
     (http://bugs.mysql.com/32785))

   * When the locale was set to Japanese, the date picker still had
     English month titles.  (Bug#32741 (http://bugs.mysql.com/32741))

   * Flashing display of a pop-up used while saving outgoing email
     settings was caused by problematic initial placement calculations.
     (Bug#32579 (http://bugs.mysql.com/32579))

   * AIX 5.2 Agent did not work on AIX 5.3.  (Bug#32414
     (http://bugs.mysql.com/32414))

   * When the First Time Setup program was run it did not prompt the
     user to allow importing an Advisor bundle.  (Bug#32199
     (http://bugs.mysql.com/32199))

   * Agent on MacOSX did not read IP addresses for network interfaces
     correctly, so the monitor displayed empty host IP addresses.
     (Bug#32188 (http://bugs.mysql.com/32188))

   * HTML code in queries was not escaped when reporting replication
     errors, causing the code to be rendered into the page.  (Bug#32186
     (http://bugs.mysql.com/32186))

   * The First Run pop-up defaulted to English rather than to the
     locale set in the browser.  (Bug#32129
     (http://bugs.mysql.com/32129))

   * The error dialog box flashed in the upper left corner before being
     positioned in the center of the screen. This error dialog box now
     opens in the center of the screen.  (Bug#32068
     (http://bugs.mysql.com/32068))

   * The Events list did not take into account Daylight Time and
     Standard Time when listing events that happened during
     1:00am-1:59am. An event that occurred at 1:10am Standard Time was
     listed before an event that occurred 50 minutes before it at
     1:20am Daylight Time.  (Bug#32016 (http://bugs.mysql.com/32016))

   * The pop-up for editing log levels failed to load due to bad
     instantiation data.  (Bug#32013 (http://bugs.mysql.com/32013))

   * During the repeated hour of Daylight Savings Time (when 2am turns
     back into 1am), the graphs were not drawing data. Instead, there
     was a straight line from the point at 1:00 to the second 1:00,
     which is what happens if there is no data. The repository did,
     however, have data for this hour.  (Bug#31997
     (http://bugs.mysql.com/31997))

   * Only US English was supported for a locale setting. Other English
     variants are now available for the `locale' setting on the `General
     Settings' or the `User Preferences' pages.  (Bug#31801
     (http://bugs.mysql.com/31801))

   * If the user locale was changed the graph cache would continue to
     display the graph in the last locale until it timed out.
     (Bug#31680 (http://bugs.mysql.com/31680))

   * No init script was installed for the MySQL Network Monitoring
     Service Manager, and so it did not restart automatically on reboot.
     (Bug#31676 (http://bugs.mysql.com/31676))

   * The graph's displayed time was not the local time of the Dashboard
     corresponding to the requested time on the monitored server.
     (Bug#31656 (http://bugs.mysql.com/31656))

   * Saving a rule with a name that already existed resulted in a stack
     trace in the window, instead of a more user-friendly error message.
     (Bug#30925 (http://bugs.mysql.com/30925))

   * The `network.mysql.com' error messages were remapped thereby
     causing confusion. For example, the following error message:

     `E9000: MySQL Enterprise Customer Center is having difficulties
     fetching your contract information. Please contact
     enterprise-feedback@mysql.com for assistance. '

     Was remapped to:

     `Unable to connect to verify credentials' (Bug#30873
     (http://bugs.mysql.com/30873))

   * A newly added server showed as `down' in the user interface, and
     could potentially have sent a false alarm notification.
     (Bug#30735 (http://bugs.mysql.com/30735))

   * The information on the `Advisors', `Check For Updates' page did
     not accurately reflect how many rules and graphs were actually in
     the database and available to the user.  (Bug#29623
     (http://bugs.mysql.com/29623))

   * The agent did not process `SIGHUP'.  (Bug#29380
     (http://bugs.mysql.com/29380))

   * Monitor did not have a facility to stop or downgrade an agent
     collection frequency.  (Bug#28589 (http://bugs.mysql.com/28589))

   * After an agent installation was updated from 1.0.1.4391 to
     1.1.0.4899, the version in the `Add/Remove Programs' menu was
     incorrectly displayed as 1.0.1.4391, even though the update was
     successful and the file version of `agent.exe' was correctly
     displayed as 1.1.0.4899.  (Bug#27447 (http://bugs.mysql.com/27447))

   * When viewing the `Results' of an `Event' in the `Events' tab of
     the `Dashboard', the `Notifications' section did not reflect the
     `Notifications' settings at the time the `Event' was triggered,
     but rather the `Notifications' settings at the time the `Event
     Results' were viewed.  (Bug#26349 (http://bugs.mysql.com/26349))

   * When the Service Agent was remotely monitoring a MySQL server it
     incorrectly reported that it could collect operating system
     information.  (Bug#22497 (http://bugs.mysql.com/22497))

   * The Account Without Password advisor did not report all users who
     were without a password, it only reported one.  (Bug#15165
     (http://bugs.mysql.com/15165))


File: manual.info,  Node: connector-odbc-news,  Next: connector-net-news,  Prev: mem-news,  Up: news

C.4 MySQL Connector/ODBC (MyODBC) Change History
================================================

* Menu:

* connector-odbc-news-5-1-6::    Changes in MySQL Connector/ODBC 5.1.6 (Not yet released)
* connector-odbc-news-5-1-5::    Changes in MySQL Connector/ODBC 5.1.5 (18 August 2008)
* connector-odbc-news-5-1-4::    Changes in MySQL Connector/ODBC 5.1.4 (15 April 2008)
* connector-odbc-news-5-1-3::    Changes in MySQL Connector/ODBC 5.1.3 (26 March 2008)
* connector-odbc-news-5-1-2::    Changes in MySQL Connector/ODBC 5.1.2 (13 February 2008)
* connector-odbc-news-5-1-1::    Changes in MySQL Connector/ODBC 5.1.1 (13 December 2007)
* connector-odbc-news-5-1-0::    Changes in MySQL Connector/ODBC 5.1.0 (10 September 2007)
* connector-odbc-news-5-0-12::   Changes in MySQL Connector/ODBC 5.0.12 (Never released)
* connector-odbc-news-5-0-11::   Changes in MySQL Connector/ODBC 5.0.11 (31 January 2007)
* connector-odbc-news-5-0-10::   Changes in MySQL Connector/ODBC 5.0.10 (14 December 2006)
* connector-odbc-news-5-0-9::    Changes in MySQL Connector/ODBC 5.0.9 (22 November 2006)
* connector-odbc-news-5-0-8::    Changes in MySQL Connector/ODBC 5.0.8 (17 November 2006)
* connector-odbc-news-5-0-7::    Changes in MySQL Connector/ODBC 5.0.7 (08 November 2006)
* connector-odbc-news-5-0-6::    Changes in MySQL Connector/ODBC 5.0.6 (03 November 2006)
* connector-odbc-news-5-0-5::    Changes in MySQL Connector/ODBC 5.0.5 (17 October 2006)
* connector-odbc-news-5-0-3::    Changes in Connector/ODBC 5.0.3 (Connector/ODBC 5.0 Alpha 3) (20 June 2006)
* connector-odbc-news-5-0-2::    Changes in Connector/ODBC 5.0.2 (Never released)
* connector-odbc-news-5-0-1::    Changes in Connector/ODBC 5.0.1 (Connector/ODBC 5.0 Alpha 2) (05 June 2006)
* connector-odbc-news-3-51-27::  Changes in MySQL Connector/ODBC 3.51.27 (20 November 2008)
* connector-odbc-news-3-51-26::  Changes in MySQL Connector/ODBC 3.51.26 (07 July 2008)
* connector-odbc-news-3-51-25::  Changes in MySQL Connector/ODBC 3.51.25 (11 April 2008)
* connector-odbc-news-3-51-24::  Changes in MySQL Connector/ODBC 3.51.24 (14 March 2008)
* connector-odbc-news-3-51-23::  Changes in MySQL Connector/ODBC 3.51.23 (09 January 2008)
* connector-odbc-news-3-51-22::  Changes in MySQL Connector/ODBC 3.51.22 (13 November 2007)
* connector-odbc-news-3-51-21::  Changes in MySQL Connector/ODBC 3.51.21 (08 October 2007)
* connector-odbc-news-3-51-20::  Changes in MySQL Connector/ODBC 3.51.20 (10 September 2007)
* connector-odbc-news-3-51-19::  Changes in MySQL Connector/ODBC 3.51.19 (10 August 2007)
* connector-odbc-news-3-51-18::  Changes in MySQL Connector/ODBC 3.51.18 (08 August 2007)
* connector-odbc-news-3-51-17::  Changes in MySQL Connector/ODBC 3.51.17 (14 July 2007)
* connector-odbc-news-3-51-16::  Changes in MySQL Connector/ODBC 3.51.16 (14 June 2007)
* connector-odbc-news-3-51-15::  Changes in MySQL Connector/ODBC 3.51.15 (07 May 2007)
* connector-odbc-news-3-51-14::  Changes in MySQL Connector/ODBC 3.51.14 (08 March 2007)
* connector-odbc-news-3-51-13::  Changes in MySQL Connector/ODBC 3.51.13 (Never released)
* connector-odbc-news-3-51-12::  Changes in MySQL Connector/ODBC 3.51.12 (11 February 2005)
* connector-odbc-news-3-51-11::  Changes in MySQL Connector/ODBC 3.51.11 (28 January 2005)


File: manual.info,  Node: connector-odbc-news-5-1-6,  Next: connector-odbc-news-5-1-5,  Prev: connector-odbc-news,  Up: connector-odbc-news

C.4.1 Changes in MySQL Connector/ODBC 5.1.6 (Not yet released)
--------------------------------------------------------------

Bugs fixed:

   * Connector/ODBC failed to build with MySQL 5.1.30 due to incorrect
     use of the data type `bool'.  (Bug#42120
     (http://bugs.mysql.com/42120))

   * Calling `SQLDescribeCol()' with a NULL buffer and non-zero buffer
     length caused a crash.  (Bug#41942 (http://bugs.mysql.com/41942))

   * MySQL Connector/ODBC updated some fields with random values,
     rather than with `NULL'.  (Bug#41256 (http://bugs.mysql.com/41256))

   * Calling `SQLDriverConnect()' with a `NULL' pointer for the output
     buffer caused a crash if `SQL_DRIVER_NOPROMPT' was also specified:

          SQLDriverConnect(dbc, NULL, "DSN=myodbc5", SQL_NTS, NULL, 0, NULL, SQL_DRIVER_NOPROMPT)

     (Bug#40316 (http://bugs.mysql.com/40316))

   * Setting the ADO `Recordset' decimal field value to 44.56 resulted
     in an incorrect value of 445600.0000 being stored when the record
     set was updated with the `Update' method.  (Bug#39961
     (http://bugs.mysql.com/39961))

   * The `SQLTablesW' API gave incorrect results.  For example, table
     name and table type were returned as `NULL' rather than as the
     correct values.  (Bug#39957 (http://bugs.mysql.com/39957))

   * If the table used any Cyrillic charset (cp1251, koi8r, cp866) and
     text columns contained symbols from these code pages, then
     `SELECT' through Connector/ODBC returned an error:

          [MySQL][ODBC 5.1 Driver][mysqld-5.0.27-community-nt]Restricted data type attribute violation

     The same is true when inserting Cyrillic characters into a text
     column in a MySQL table, through Connector/ODBC.  (Bug#39831
     (http://bugs.mysql.com/39831))

   * When the SQLTables method was called with `NULL' passed as the
     `tablename' parameter, only one row in the `resultset', with table
     name of `NULL' was returned, instead of all tables for the given
     database.  (Bug#39561 (http://bugs.mysql.com/39561))

   * The `SQLGetInfo()' function returned 0 for `SQL_CATALOG_USAGE'
     information.  (Bug#39560 (http://bugs.mysql.com/39560))

   * MyODBC Driver 5.1.5 was not able to connect if the connection
     string parameters contained spaces or tab symbols. For example, if
     the `SERVER' parameter was specified as `SERVER= localhost'
     instead of `SERVER=localhost' the following error message will be
     displayed:

          [MySQL][ODBC 5.1 Driver] Unknown MySQL server host ' localhost' (11001).

     (Bug#39085 (http://bugs.mysql.com/39085))

   * The pointer passed to the SQLDriverConnect method to retrieve the
     output connection string length was one greater than it should
     have been due to the inclusion of the NULL terminator.  (Bug#38949
     (http://bugs.mysql.com/38949))

   * Data-at-execution parameters were not supported during positioned
     update. This meant updating a long text field with a cursor update
     would erroneously set the value to null. This would lead to the
     error `Column 'column_name' cannot be null' while updating the
     database, even when `column_name' had been assigned a valid
     non-null string.  (Bug#37649 (http://bugs.mysql.com/37649))

   * The SQLDriverConnect method truncated the `OutputConnectionString'
     parameter to 52 characters.  (Bug#37278
     (http://bugs.mysql.com/37278))

   * The connection string option `Enable Auto-reconnect' did not work.
     When the connection failed, it could not be restored, and the
     errors generated were the same as if the option had not been
     selected.  (Bug#37179 (http://bugs.mysql.com/37179))

   * No result record was returned for `SQLGetTypeInfo' for the
     `TIMESTAMP' data type. An application would receive the result
     `return code 100 (SQL_NO_DATA_FOUND)'.  (Bug#30626
     (http://bugs.mysql.com/30626))

   * It was not possible to use Connector/ODBC to connect to a server
     using SSL. The following error was generated:

          Runtime error '-2147467259 (80004005)':

          [MySQL][ODBC 3.51 Driver]SSL connection error.

     (Bug#29955 (http://bugs.mysql.com/29955))

   * When the `recordSet.Update' function was called to update an
     `adLongVarChar' field, the field was updated but the recordset was
     immediately lost. This happened with driver cursors, whether the
     cursor was opened in optimistic or pessimistic mode.

     When the next update was called the test code would exit with the
     following error:

          -2147467259 : Query-based update failed because the row to update could not be found.

     (Bug#26950 (http://bugs.mysql.com/26950))


File: manual.info,  Node: connector-odbc-news-5-1-5,  Next: connector-odbc-news-5-1-4,  Prev: connector-odbc-news-5-1-6,  Up: connector-odbc-news

C.4.2 Changes in MySQL Connector/ODBC 5.1.5 (18 August 2008)
------------------------------------------------------------

Bugs fixed:

   * ODBC *Note `TIMESTAMP': datetime. string format is not handled
     properly by the MyODBC driver. When passing a *Note `TIMESTAMP':
     datetime. or *Note `DATE': datetime. to MyODBC, in the ODBC
     format: {d <date>} or {ts <timestamp>}, the string that represents
     this is copied once into the SQL statement, and then added again,
     as an escaped string.  (Bug#37342 (http://bugs.mysql.com/37342))

   * The connector failed to prompt for additional information required
     to create a DSN-less connection from an application such as
     Microsoft Excel.  (Bug#37254 (http://bugs.mysql.com/37254))

   * `SQLDriverConnect' does not return `SQL_NO_DATA' on cancel. The
     ODBC documentation specifies that this method should return
     `SQL_NO_DATA' when the user cancels the dialog to connect. The
     connector, however, returns `SQL_ERROR'.  (Bug#36293
     (http://bugs.mysql.com/36293))

   * Assigning a string longer than 67 characters to the `TableType'
     parameter resulted in a buffer overrun when the `SQLTables()'
     function was called.  (Bug#36275 (http://bugs.mysql.com/36275))

   * The ODBC connector randomly uses logon information stored in
     `odbc-profile', or prompts the user for connection information and
     ignores any settings stored in `odbc-profile'.  (Bug#36203
     (http://bugs.mysql.com/36203))

   * After having successfully established a connection, a crash occurs
     when calling `SQLProcedures()' followed by `SQLFreeStmt()', using
     the ODBC C API.  (Bug#36069 (http://bugs.mysql.com/36069))


File: manual.info,  Node: connector-odbc-news-5-1-4,  Next: connector-odbc-news-5-1-3,  Prev: connector-odbc-news-5-1-5,  Up: connector-odbc-news

C.4.3 Changes in MySQL Connector/ODBC 5.1.4 (15 April 2008)
-----------------------------------------------------------

Bugs fixed:

   * Wrong result obtained when using `sum()' on a `decimal(8,2)' field
     type.  (Bug#35920 (http://bugs.mysql.com/35920))

   * The driver installer could not create a new DSN if many other
     drivers were already installed.  (Bug#35776
     (http://bugs.mysql.com/35776))

   * The `SQLColAttribute()' function returned `SQL_TRUE' when querying
     the `SQL_DESC_FIXED_PREC_SCALE (SQL_COLUMN_MONEY)' attribute of a
     *Note `DECIMAL': numeric-types. column.  Previously, the correct
     value of `SQL_FALSE' was returned; this is now again the case.
     (Bug#35581 (http://bugs.mysql.com/35581))

   * On Linux, `SQLGetDiagRec()' returned `SQL_SUCCESS' in cases when
     it should have returned `SQL_NO_DATA'.  (Bug#33910
     (http://bugs.mysql.com/33910))

   * The driver crashes ODBC Administrator on attempting to add a new
     DSN.  (Bug#32057 (http://bugs.mysql.com/32057))


File: manual.info,  Node: connector-odbc-news-5-1-3,  Next: connector-odbc-news-5-1-2,  Prev: connector-odbc-news-5-1-4,  Up: connector-odbc-news

C.4.4 Changes in MySQL Connector/ODBC 5.1.3 (26 March 2008)
-----------------------------------------------------------

Platform specific notes:

   * *Important Change*: You must uninstall previous 5.1.x editions of
     Connector/ODBC before installing the new version.

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * The installer for 64-bit Windows installs both the 32-bit and
     64-bit driver. Please note that Microsoft does not yet supply a
     64-bit bridge from ADO to ODBC.

Bugs fixed:

   * *Important Change*: In previous versions, the SSL certificate
     would automatically be verified when used as part of the
     Connector/ODBC connection. The default mode is now to ignore the
     verificate of certificates. To enforce verification of the SSL
     certificate during connection, use the `SSLVERIFY' DSN parameter,
     setting the value to 1.  (Bug#29955 (http://bugs.mysql.com/29955),
     Bug#34648 (http://bugs.mysql.com/34648))

   * Inserting characters to a UTF8 table using surrogate pairs would
     fail and insert invalid data.  (Bug#34672
     (http://bugs.mysql.com/34672))

   * Installation of Connector/ODBC would fail because it was unable to
     uninstall a previous installed version. The file being requested
     would match an older release version than any installed version of
     the connector.  (Bug#34522 (http://bugs.mysql.com/34522))

   * Using `SqlGetData' in combination with `SQL_C_WCHAR' would return
     overlapping data.  (Bug#34429 (http://bugs.mysql.com/34429))

   * Descriptor records were not cleared correctly when calling
     `SQLFreeStmt(SQL_UNBIND)'.  (Bug#34271
     (http://bugs.mysql.com/34271))

   * The dropdown selection for databases on a server when creating a
     DSN was too small. The list size now automatically adjusts up to a
     maximum size of 20 potential databases.  (Bug#33918
     (http://bugs.mysql.com/33918))

   * Microsoft Access would be unable to use
     `DBEngine.RegisterDatabase' to create a DSN using the
     Connector/ODBC driver.  (Bug#33825 (http://bugs.mysql.com/33825))

   * Connector/ODBC erroneously reported that it supported the `CAST()'
     and `CONVERT()' ODBC functions for parsing values in SQL
     statements, which could lead to bad SQL generation during a query.
     (Bug#33808 (http://bugs.mysql.com/33808))

   * Using a linked table in Access 2003 where the table has a *Note
     `BIGINT': numeric-types. column as the first column in the table,
     and is configured as the primary key, shows `#DELETED' for all
     rows of the table.  (Bug#24535 (http://bugs.mysql.com/24535))

   * Updating a `RecordSet' when the query involves a *Note `BLOB':
     blob. field would fail.  (Bug#19065 (http://bugs.mysql.com/19065))


File: manual.info,  Node: connector-odbc-news-5-1-2,  Next: connector-odbc-news-5-1-1,  Prev: connector-odbc-news-5-1-3,  Up: connector-odbc-news

C.4.5 Changes in MySQL Connector/ODBC 5.1.2 (13 February 2008)
--------------------------------------------------------------

MySQL Connector/ODBC 5.1.2-beta, a new version of the ODBC driver for
the MySQL database management system, has been released. This release
is the second beta (feature-complete) release of the new 5.1 series and
is suitable for use with any MySQL server version since MySQL 4.1,
including MySQL 5.0, 5.1, and 6.0. (It will not work with 4.0 or
earlier releases.)

Keep in mind that this is a beta release, and as with any other
pre-production release, caution should be taken when installing on
production level systems or systems with critical data.

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * The installer for 64-bit Windows installs both the 32-bit and
     64-bit driver. Please note that Microsoft does not yet supply a
     64-bit bridge from ADO to ODBC.

   * Due to differences with the installation process used on Windows
     and potential registry corruption, it is recommended that
     uninstall any existing versions of Connector/ODBC 5.1.x before
     upgrading.

     See also Bug#34571 (http://bugs.mysql.com/34571).

Functionality added or changed:

   * Explicit descriptors are implemented.  (Bug#32064
     (http://bugs.mysql.com/32064))

   * A full implementation of SQLForeignKeys based on the information
     available from INFORMATION_SCHEMA in 5.0 and later versions of the
     server has been implemented.

   * Changed `SQL_ATTR_PARAMSET_SIZE' to return an error until support
     for it is implemented.

   * Disabled `MYSQL_OPT_SSL_VERIFY_SERVER_CERT' when using an SSL
     connection.

   * `SQLForeignKeys' uses `INFORMATION_SCHEMA' when it is available on
     the server, which allows more complete information to be returned.

Bugs fixed:

   * The `SSLCIPHER' option would be incorrectly recorded within the
     SSL configuration on Windows.  (Bug#33897
     (http://bugs.mysql.com/33897))

   * Within the GUI interface, when connecting to a MySQL server on a
     non-standard port, the connection test within the GUI would fail.
     The issue was related to incorrect parsing of numeric values
     within the DSN when the option was not configured as the last
     parameter within the DSN.  (Bug#33822
     (http://bugs.mysql.com/33822))

   * Specifying a non-existent database name within the GUI dialog
     would result in an empty list, not an error.  (Bug#33615
     (http://bugs.mysql.com/33615))

   * When deleting rows from a static cursor, the cursor position would
     be incorrectly reported.  (Bug#33388 (http://bugs.mysql.com/33388))

   * `SQLGetInfo()' reported characters for `SQL_SPECIAL_CHARACTERS'
     that were not encoded correctly.  (Bug#33130
     (http://bugs.mysql.com/33130))

   * Retrieving data from a *Note `BLOB': blob.  column would fail
     within `SQLGetData'when the target data type was `SQL_C_WCHAR' due
     to incorrect handling of the character buffer.  (Bug#32684
     (http://bugs.mysql.com/32684))

   * Renaming an existing DSN entry would create a new entry with the
     new name without deleting the old entry.  (Bug#31165
     (http://bugs.mysql.com/31165))

   * Reading a *Note `TEXT': blob. column that had been used to store
     UTF8 data would result in the wrong information being returned
     during a query.  (Bug#28617 (http://bugs.mysql.com/28617))

   * `SQLForeignKeys' would return an empty string for the schema
     columns instead of `NULL'.  (Bug#19923
     (http://bugs.mysql.com/19923))

   * When accessing column data, `FLAG_COLUMN_SIZE_S32' did not limit
     the octet length or display size reported for fields, causing
     problems with Microsoft Visual FoxPro.

     The list of ODBC functions that could have caused failures in
     Microsoft software when retrieving the length of *Note `LONGBLOB':
     blob. or *Note `LONGTEXT': blob. columns includes:

        * `SQLColumns'

        * `SQLColAttribute'

        * `SQLColAttributes'

        * `SQLDescribeCol'

        * `SQLSpecialColumns' (theoretically can have the same problem)

     (Bug#12805 (http://bugs.mysql.com/12805), Bug#30890
     (http://bugs.mysql.com/30890))

   * Dynamic cursors on statements with parameters were not supported.
     (Bug#11846 (http://bugs.mysql.com/11846))

   * Evaluating a simple numeric expression when using the OLEDB for
     ODBC provider and ADO would return an error, instead of the result.
     (Bug#10128 (http://bugs.mysql.com/10128))

   * Adding or updating a row using `SQLSetPos()' on a result set with
     aliased columns would fail.  (Bug#6157
     (http://bugs.mysql.com/6157))


File: manual.info,  Node: connector-odbc-news-5-1-1,  Next: connector-odbc-news-5-1-0,  Prev: connector-odbc-news-5-1-2,  Up: connector-odbc-news

C.4.6 Changes in MySQL Connector/ODBC 5.1.1 (13 December 2007)
--------------------------------------------------------------

MySQL Connector/ODBC 5.1.1-beta, a new version of the ODBC driver for
the MySQL database management system, has been released. This release
is the first beta (feature-complete) release of the new 5.1 series and
is suitable for use with any MySQL server version since MySQL 4.1,
including MySQL 5.0, 5.1, and 6.0. (It will not work with 4.0 or
earlier releases.)

Keep in mind that this is a beta release, and as with any other
pre-production release, caution should be taken when installing on
production level systems or systems with critical data.

Includes changes from *Note Connector/ODBC 3.51.21:
connector-odbc-news-3-51-21. and *Note 3.51.22:
connector-odbc-news-3-51-22.

Built using MySQL 5.0.52.

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * The installer for 64-bit Windows installs both the 32-bit and
     64-bit driver. Please note that Microsoft does not yet supply a
     64-bit bridge from ADO to ODBC.

   * Due to differences with the installation process used on Windows
     and potential registry corruption, it is recommended that
     uninstall any existing versions of Connector/ODBC 5.1.x before
     upgrading.

     See also Bug#34571 (http://bugs.mysql.com/34571).

Functionality added or changed:

   * *Incompatible Change*: Replaced myodbc3i (now myodbc-installer)
     with Connector/ODBC 5.0 version.

   * *Incompatible Change*: Removed monitor (myodbc3m) and dsn-editor
     (myodbc3c).

   * *Incompatible Change*: Disallow `SET NAMES' in initial statement
     and in executed statements.

   * A wrapper for the `SQLGetPrivateProfileStringW()' function, which
     is required for Unicode support, has been created. This function
     is missing from the unixODBC driver manager.  (Bug#32685
     (http://bugs.mysql.com/32685))

   * Added MSI installer for Windows 64-bit.  (Bug#31510
     (http://bugs.mysql.com/31510))

   * Implemented support for `SQLCancel()'.  (Bug#15601
     (http://bugs.mysql.com/15601))

   * Added support for `SQL_NUMERIC_STRUCT'.  (Bug#3028
     (http://bugs.mysql.com/3028), Bug#24920
     (http://bugs.mysql.com/24920))

   * Removed non-threadsafe configuration of the driver. The driver is
     now always built against the threadsafe version of libmysql.

   * Implemented native Windows setup library

   * Replaced the internal library which handles creation and loading
     of DSN information. The new library, which was originally a part
     of Connector/ODBC 5.0, supports Unicode option values.

   * The Windows installer now places files in a subdirectory of the
     `Program Files' directory instead of the Windows system directory.

Bugs fixed:

   * The `SET NAMES' statement has been disabled because it causes
     problems in the ODBC driver when determining the current client
     character set.  (Bug#32596 (http://bugs.mysql.com/32596))

   * `SQLDescribeColW' returned UTF-8 column as `SQL_VARCHAR' instead of
     `SQL_WVARCHAR'.  (Bug#32161 (http://bugs.mysql.com/32161))

   * ADO was unable to open record set using dynamic cursor.
     (Bug#32014 (http://bugs.mysql.com/32014))

   * ADO applications would not open a `RecordSet' that contained a
     *Note `DECIMAL': numeric-types. field.  (Bug#31720
     (http://bugs.mysql.com/31720))

   * Memory usage would increase considerably.  (Bug#31115
     (http://bugs.mysql.com/31115))

   * SQL statements are limited to 64KB.  (Bug#30983
     (http://bugs.mysql.com/30983), Bug#30984
     (http://bugs.mysql.com/30984))

   * `SQLSetPos' with `SQL_DELETE' advances dynamic cursor incorrectly.
     (Bug#29765 (http://bugs.mysql.com/29765))

   * Using an ODBC prepared statement with bound columns would produce
     an empty result set when called immediately after inserting a row
     into a table.  (Bug#29239 (http://bugs.mysql.com/29239))

   * ADO Not possible to update a client side cursor.  (Bug#27961
     (http://bugs.mysql.com/27961))

   * Recordset `Update()' fails when using `adUseClient' cursor.
     (Bug#26985 (http://bugs.mysql.com/26985))

   * Connector/ODBC would fail to connect to the server if the password
     contained certain characters, including the semicolon and other
     punctuation marks.  (Bug#16178 (http://bugs.mysql.com/16178))

   * Fixed `SQL_ATTR_PARAM_BIND_OFFSET', and fixed row offsets to work
     with updatable cursors.

   * `SQLSetConnectAttr()' did not clear previous errors, possibly
     confusing `SQLError()'.

   * `SQLError()' incorrectly cleared the error information, making it
     unavailable from subsequent calls to `SQLGetDiagRec()'.

   * NULL pointers passed to `SQLGetInfo()' could result in a crash.

   * `SQL_ODBC_SQL_CONFORMANCE' was not handled by `SQLGetInfo()'.

   * `SQLCopyDesc()' did not correctly copy all records.

   * Diagnostics were not correctly cleared on connection and
     environment handles.


File: manual.info,  Node: connector-odbc-news-5-1-0,  Next: connector-odbc-news-5-0-12,  Prev: connector-odbc-news-5-1-1,  Up: connector-odbc-news

C.4.7 Changes in MySQL Connector/ODBC 5.1.0 (10 September 2007)
---------------------------------------------------------------

This release is the first of the new 5.1 series and is suitable for use
with any MySQL server version since MySQL 4.1, including MySQL 5.0,
5.1, and 6.0. (It will not work with 4.0 or earlier releases.)

Keep in mind that this is a alpha release, and as with any other
pre-production release, caution should be taken when installing on
production level systems or systems with critical data. Not all of the
features planned for the final Connector/ODBC 5.1 release are
implemented.

Functionality is based on Connector/ODBC 3.51.20.

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * There are no installer packages for Microsoft Windows x64 Edition.

   * Due to differences with the installation process used on Windows
     and potential registry corruption, it is recommended that
     uninstall any existing versions of Connector/ODBC 5.1.x before
     upgrading.

     See also Bug#34571 (http://bugs.mysql.com/34571).

Functionality added or changed:

   * Added support for Unicode functions (`SQLConnectW', etc).

   * Added descriptor support (`SQLGetDescField', `SQLGetDescRec', etc).

   * Added support for `SQL_C_WCHAR'.


File: manual.info,  Node: connector-odbc-news-5-0-12,  Next: connector-odbc-news-5-0-11,  Prev: connector-odbc-news-5-1-0,  Up: connector-odbc-news

C.4.8 Changes in MySQL Connector/ODBC 5.0.12 (Never released)
-------------------------------------------------------------

*Note*:

Development on Connector/ODBC 5.0.x has ceased. New features and
functionality will be incorporated into Connector/ODBC 5.1. See *Note
connector-odbc-roadmap::.

Bugs fixed:

   * Inserting `NULL' values into a *Note `DATETIME': datetime. column
     from Access reports an error.  (Bug#27896
     (http://bugs.mysql.com/27896))

   * Tables with *Note `TEXT': blob. columns would be incorrectly
     identified, returning an `Unknown SQL type - 65535' error.
     (Bug#20127 (http://bugs.mysql.com/20127))


File: manual.info,  Node: connector-odbc-news-5-0-11,  Next: connector-odbc-news-5-0-10,  Prev: connector-odbc-news-5-0-12,  Up: connector-odbc-news

C.4.9 Changes in MySQL Connector/ODBC 5.0.11 (31 January 2007)
--------------------------------------------------------------

Functionality added or changed:

   * Added support for ODBC v2 statement options using attributes.

   * Driver now builds and is partially tested under Linux with the
     iODBC driver manager.

Bugs fixed:

   * Connection string parsing for DSN-less connections could fail to
     identify some parameters.  (Bug#25316
     (http://bugs.mysql.com/25316))

   * Updates of `MEMO' or *Note `TEXT': blob. columns from within
     Microsoft Access would fail.  (Bug#25263
     (http://bugs.mysql.com/25263))

   * Transaction support has been added and tested.  (Bug#25045
     (http://bugs.mysql.com/25045))

   * Internal function, `my_setpos_delete_ignore()' could cause a crash.
     (Bug#22796 (http://bugs.mysql.com/22796))

   * Fixed occasional mis-handling of the `SQL_NUMERIC_C' type.

   * Fixed the binding of certain integer types.


File: manual.info,  Node: connector-odbc-news-5-0-10,  Next: connector-odbc-news-5-0-9,  Prev: connector-odbc-news-5-0-11,  Up: connector-odbc-news

C.4.10 Changes in MySQL Connector/ODBC 5.0.10 (14 December 2006)
----------------------------------------------------------------

Connector/ODBC 5.0.10 is the sixth BETA release.

Functionality added or changed:

   * Significant performance improvement when retrieving large text
     fields in pieces using `SQLGetData()' with a buffer smaller than
     the whole data. Mainly used in Access when fetching very large
     text fields.  (Bug#24876 (http://bugs.mysql.com/24876))

   * Added initial unicode support in data and metadata.  (Bug#24837
     (http://bugs.mysql.com/24837))

   * Added initial support for removing braces when calling stored
     procedures and retrieving result sets from procedure calls.
     (Bug#24485 (http://bugs.mysql.com/24485))

   * Added loose handling of retrieving some diagnostic data.
     (Bug#15782 (http://bugs.mysql.com/15782))

   * Added wide-string type info for `SQLGetTypeInfo()'.

Bugs fixed:

   * Editing DSN no longer crashes ODBC data source administrator.
     (Bug#24675 (http://bugs.mysql.com/24675))

   * String query parameters are new escaped correctly.  (Bug#19078
     (http://bugs.mysql.com/19078))


File: manual.info,  Node: connector-odbc-news-5-0-9,  Next: connector-odbc-news-5-0-8,  Prev: connector-odbc-news-5-0-10,  Up: connector-odbc-news

C.4.11 Changes in MySQL Connector/ODBC 5.0.9 (22 November 2006)
---------------------------------------------------------------

Connector/ODBC 5.0.9 is the fifth BETA release.

This is an implementation and testing release, and is not designed for
use within a production environment.

Functionality added or changed:

   * Added support for column binding as SQL_NUMBERIC_STRUCT.

   * Added recognition of `SQL_C_SHORT' and `SQL_C_TINYINT' as C types.

Bugs fixed:

   * Fixed wildcard handling of and listing of catalogs and tables in
     `SQLTables'.

   * Added limit of display size when requested via
     `SQLColAttribute'/`SQL_DESC_DISPLAY_SIZE'.

   * Fixed buffer length return for SQLDriverConnect.

   * ODBC v2 behaviour in driver now supports ODBC v3 date/time types
     (since DriverManager maps them).

   * Catch use of `SQL_ATTR_PARAMSET_SIZE' and report error until we
     fully support.

   * Fixed statistics to fail if it couldn't be completed.

   * Corrected retrieval multiple field types bit and blob/text.

   * Fixed SQLGetData to clear the NULL indicator correctly during
     multiple calls.


File: manual.info,  Node: connector-odbc-news-5-0-8,  Next: connector-odbc-news-5-0-7,  Prev: connector-odbc-news-5-0-9,  Up: connector-odbc-news

C.4.12 Changes in MySQL Connector/ODBC 5.0.8 (17 November 2006)
---------------------------------------------------------------

Connector/ODBC 5.0.8 is the fourth BETA release.

This is an implementation and testing release, and is not designed for
use within a production environment.

Functionality added or changed:

   * Also made `SQL_DESC_NAME' only fill in the name if there was a
     data pointer given, otherwise just the length.

   * Fixed display size to be length if max length isn't available.

   * Made distinction between *Note `CHAR': char./*Note `BINARY':
     binary-varbinary.  (and VAR versions).

   * Wildcards now support escaped chars and underscore matching
     (needed to link tables with underscores in access).

Bugs fixed:

   * Fixed binding using `SQL_C_LONG'.

   * Fixed using wrong pointer for `SQL_MAX_DRIVER_CONNECTIONS' in
     `SQLGetInfo'.

   * Set default return to `SQL_SUCCESS' if nothing is done for
     `SQLSpecialColumns'.

   * Fixed MDiagnostic to use correct v2/v3 error codes.

   * Allow SQLDescribeCol to be called to retrieve the length of the
     column name, but not the name itself.

   * Length now used when handling bind parameter (needed in particular
     for `SQL_WCHAR') - this enables updating char data in MS Access.

   * Updated retrieval of descriptor fields to use the right pointer
     types.

   * Fixed hanlding of numeric pointers in SQLColAttribute.

   * Fixed type returned for `MYSQL_TYPE_LONG' to `SQL_INTEGER' instead
     of `SQL_TINYINT'.

   * Fix size return from `SQLDescribeCol'.

   * Fixed string length to chars, not bytes, returned by SQLGetDiagRec.


File: manual.info,  Node: connector-odbc-news-5-0-7,  Next: connector-odbc-news-5-0-6,  Prev: connector-odbc-news-5-0-8,  Up: connector-odbc-news

C.4.13 Changes in MySQL Connector/ODBC 5.0.7 (08 November 2006)
---------------------------------------------------------------

Connector/ODBC 5.0.7 is the third BETA release.

This is an implementation and testing release, and is not designed for
use within a production environment.

Functionality added or changed:

   * Added support for `SQLStatistics' to `MYODBCShell'.

   * Improved trace/log.

Bugs fixed:

   * SQLBindParameter now handles `SQL_C_DEFAULT'.

   * Corrected incorrect column index within `SQLStatistics'. Many more
     tables can now be linked into MS Access.

   * Fixed `SQLDescribeCol' returning column name length in bytes
     rather than chars.


File: manual.info,  Node: connector-odbc-news-5-0-6,  Next: connector-odbc-news-5-0-5,  Prev: connector-odbc-news-5-0-7,  Up: connector-odbc-news

C.4.14 Changes in MySQL Connector/ODBC 5.0.6 (03 November 2006)
---------------------------------------------------------------

Connector/ODBC 5.0.6 is the second BETA release.

This is an implementation and testing release, and is not designed for
use within a production environment.

Features, limitations and notes on this release

   * Connector/ODBC supports both `User' and `System' DSNs.

   * Installation is provided in the form of a standard Microsoft
     System Installer (MSI).

   * You no longer have to have Connector/ODBC 3.51 installed before
     installing this version.

Bugs fixed:

   * You no longer have to have Connector/ODBC 3.51 installed before
     installing this version.

   * Connector/ODBC supports both `User' and `System' DSNs.

   * Installation is provided in the form of a standard Microsoft
     System Installer (MSI).


File: manual.info,  Node: connector-odbc-news-5-0-5,  Next: connector-odbc-news-5-0-3,  Prev: connector-odbc-news-5-0-6,  Up: connector-odbc-news

C.4.15 Changes in MySQL Connector/ODBC 5.0.5 (17 October 2006)
--------------------------------------------------------------

Connector/ODBC 5.0.5 is the first BETA release.

This is an implementation and testing release, and is not designed for
use within a production environment.

You no longer have to have Connector/ODBC 3.51 installed before
installing this version.

Bugs fixed:

   * You no longer have to have Connector/ODBC 3.51 installed before
     installing this version.


File: manual.info,  Node: connector-odbc-news-5-0-3,  Next: connector-odbc-news-5-0-2,  Prev: connector-odbc-news-5-0-5,  Up: connector-odbc-news

C.4.16 Changes in Connector/ODBC 5.0.3 (Connector/ODBC 5.0 Alpha 3) (20 June 2006)
----------------------------------------------------------------------------------

This is an implementation and testing release, and is not designed for
use within a production environment.

Features, limitations and notes on this release:

   * The following ODBC API functions have been added in this release:

        * `SQLBindParameter'

        * `SQLBindCol'


File: manual.info,  Node: connector-odbc-news-5-0-2,  Next: connector-odbc-news-5-0-1,  Prev: connector-odbc-news-5-0-3,  Up: connector-odbc-news

C.4.17 Changes in Connector/ODBC 5.0.2 (Never released)
-------------------------------------------------------

Connector/ODBC 5.0.2 was an internal implementation and testing release.


File: manual.info,  Node: connector-odbc-news-5-0-1,  Next: connector-odbc-news-3-51-27,  Prev: connector-odbc-news-5-0-2,  Up: connector-odbc-news

C.4.18 Changes in Connector/ODBC 5.0.1 (Connector/ODBC 5.0 Alpha 2) (05 June 2006)
----------------------------------------------------------------------------------

Features, limitations and notes on this release:

   * Connector/ODBC 5.0 is Unicode aware.

   * Connector/ODBC is currently limited to basic applications. ADO
     applications and Microsoft Office are not supported.

   * Connector/ODBC must be used with a Driver Manager.

   * The following ODBC API functions are implemented:

        * `SQLAllocHandle'

        * `SQLCloseCursor'

        * `SQLColAttribute'

        * `SQLColumns'

        * `SQLConnect'

        * `SQLCopyDesc'

        * `SQLDisconnect'

        * `SQLExecDirect'

        * `SQLExecute'

        * `SQLFetch'

        * `SQLFreeHandle'

        * `SQLFreeStmt'

        * `SQLGetConnectAttr'

        * `SQLGetData'

        * `SQLGetDescField'

        * `SQLGetDescRec'

        * `SQLGetDiagField'

        * `SQLGetDiagRec'

        * `SQLGetEnvAttr'

        * `SQLGetFunctions'

        * `SQLGetStmtAttr'

        * `SQLGetTypeInfo'

        * `SQLNumResultCols'

        * `SQLPrepare'

        * `SQLRowcount'

        * `SQLTables'

     The following ODBC API function are implemented, but not yet
     support all the available attributes/options:

        * `SQLSetConnectAttr'

        * `SQLSetDescField'

        * `SQLSetDescRec'

        * `SQLSetEnvAttr'

        * `SQLSetStmtAttr'


File: manual.info,  Node: connector-odbc-news-3-51-27,  Next: connector-odbc-news-3-51-26,  Prev: connector-odbc-news-5-0-1,  Up: connector-odbc-news

C.4.19 Changes in MySQL Connector/ODBC 3.51.27 (20 November 2008)
-----------------------------------------------------------------

Bugs fixed:

   * The client program hung when the network connection to the server
     was interrupted.  (Bug#40407 (http://bugs.mysql.com/40407))

   * The connection string option `Enable Auto-reconnect' did not work.
     When the connection failed, it could not be restored, and the
     errors generated were the same as if the option had not been
     selected.  (Bug#37179 (http://bugs.mysql.com/37179))

   * It was not possible to use Connector/ODBC to connect to a server
     using SSL. The following error was generated:

          Runtime error '-2147467259 (80004005)':

          [MySQL][ODBC 3.51 Driver]SSL connection error.

     (Bug#29955 (http://bugs.mysql.com/29955))


File: manual.info,  Node: connector-odbc-news-3-51-26,  Next: connector-odbc-news-3-51-25,  Prev: connector-odbc-news-3-51-27,  Up: connector-odbc-news

C.4.20 Changes in MySQL Connector/ODBC 3.51.26 (07 July 2008)
-------------------------------------------------------------

Functionality added or changed:

   * There is a new connection option, `FLAG_NO_BINARY_RESULT'. When
     set this option disables charset 63 for columns with an empty
     `org_table'.  (Bug#29402 (http://bugs.mysql.com/29402))

Bugs fixed:

   * When an ADOConnection is created and attempts to open a schema with
     ADOConnection.OpenSchema an access violation occurs in
     `myodbc3.dll'.  (Bug#30770 (http://bugs.mysql.com/30770))

   * When *Note `SHOW CREATE TABLE': show-create-table. was invoked and
     then the field values read, the result was truncated and unusable
     if the table had many rows and indexes.  (Bug#24131
     (http://bugs.mysql.com/24131))


File: manual.info,  Node: connector-odbc-news-3-51-25,  Next: connector-odbc-news-3-51-24,  Prev: connector-odbc-news-3-51-26,  Up: connector-odbc-news

C.4.21 Changes in MySQL Connector/ODBC 3.51.25 (11 April 2008)
--------------------------------------------------------------

Bugs fixed:

   * The `SQLColAttribute()' function returned `SQL_TRUE' when querying
     the `SQL_DESC_FIXED_PREC_SCALE (SQL_COLUMN_MONEY)' attribute of a
     *Note `DECIMAL': numeric-types. column.  Previously, the correct
     value of `SQL_FALSE' was returned; this is now again the case.
     (Bug#35581 (http://bugs.mysql.com/35581))

   * The driver crashes ODBC Administrator on attempting to add a new
     DSN.  (Bug#32057 (http://bugs.mysql.com/32057))

   * When accessing column data, `FLAG_COLUMN_SIZE_S32' did not limit
     the octet length or display size reported for fields, causing
     problems with Microsoft Visual FoxPro.

     The list of ODBC functions that could have caused failures in
     Microsoft software when retrieving the length of *Note `LONGBLOB':
     blob. or *Note `LONGTEXT': blob. columns includes:

        * `SQLColumns'

        * `SQLColAttribute'

        * `SQLColAttributes'

        * `SQLDescribeCol'

        * `SQLSpecialColumns' (theoretically can have the same problem)

     (Bug#12805 (http://bugs.mysql.com/12805), Bug#30890
     (http://bugs.mysql.com/30890))


File: manual.info,  Node: connector-odbc-news-3-51-24,  Next: connector-odbc-news-3-51-23,  Prev: connector-odbc-news-3-51-25,  Up: connector-odbc-news

C.4.22 Changes in MySQL Connector/ODBC 3.51.24 (14 March 2008)
--------------------------------------------------------------

Bugs fixed:

   * *Security Enhancement*: Accessing a parameer with the type of
     `SQL_C_CHAR', but with a numeric type and a length of zero, the
     parameter marker would get stropped from the query. In addition,
     an SQL injection was possible if the parameter value had a
     non-zero length and was not numeric, the text would be inserted
     verbatim.  (Bug#34575 (http://bugs.mysql.com/34575))

   * *Important Change*: In previous versions, the SSL certificate
     would automatically be verified when used as part of the
     Connector/ODBC connection. The default mode is now to ignore the
     verificate of certificates. To enforce verification of the SSL
     certificate during connection, use the `SSLVERIFY' DSN parameter,
     setting the value to 1.  (Bug#29955 (http://bugs.mysql.com/29955),
     Bug#34648 (http://bugs.mysql.com/34648))

   * When using ADO, the count of parameters in a query would always
     return zero.  (Bug#33298 (http://bugs.mysql.com/33298))

   * Using tables with a single quote or other non-standard characters
     in the table or column names through ODBC would fail.  (Bug#32989
     (http://bugs.mysql.com/32989))

   * When using Crystal Reports, table and column names would be
     truncated to 21 characters, and truncated columns in tables where
     the truncated name was the duplicated would lead to only a single
     column being displayed.  (Bug#32864 (http://bugs.mysql.com/32864))

   * `SQLExtendedFetch()' and `SQLFetchScroll()' ignored the rowset
     size if the `Don't cache result' DSN option was set.  (Bug#32420
     (http://bugs.mysql.com/32420))

   * When using the ODBC `SQL_TXN_READ_COMMITTED' option, 'dirty'
     records would be read from tables as if the option had not been
     applied.  (Bug#31959 (http://bugs.mysql.com/31959))

   * When creating a System DSN using the ODBC Administrator on Mac OS
     X, a User DSN would be created instead. The root cause is a
     problem with the iODBC driver manager used on Mac OS X. The fix
     works around this issue.

     *Note*:

     ODBC Administrator may still be unable to register a System DSN
     unless the `/Library/ODBC/odbc.ini' file has the correct
     permissions. You should ensure that the file is writable by the
     `admin' group.

     (Bug#31495 (http://bugs.mysql.com/31495))

   * Calling `SQLFetch' or `SQLFetchScroll' would return negative data
     lengths when using `SQL_C_WCHAR'.  (Bug#31220
     (http://bugs.mysql.com/31220))

   * `SQLSetParam()' caused memory allocation errors due to driver
     manager's mapping of deprecated functions (buffer length -1).
     (Bug#29871 (http://bugs.mysql.com/29871))

   * Static cursor was unable to be used through ADO when dynamic
     cursors were enabled.  (Bug#27351 (http://bugs.mysql.com/27351))

   * Using `connection.Execute' to create a record set based on a table
     without declaring the cmd option as `adCmdTable' will fail when
     communicating with versions of MySQL 5.0.37 and higher. The issue
     is related to the way that `SQLSTATE' is returned when ADO tries
     to confirm the existence of the target object.  (Bug#27158
     (http://bugs.mysql.com/27158))

   * Updating a `RecordSet' when the query involves a *Note `BLOB':
     blob. field would fail.  (Bug#19065 (http://bugs.mysql.com/19065))

   * With some connections to MySQL databases using Connector/ODBC, the
     connection would mistakenly report 'user cancelled' for accesses
     to the database information.  (Bug#16653
     (http://bugs.mysql.com/16653))


File: manual.info,  Node: connector-odbc-news-3-51-23,  Next: connector-odbc-news-3-51-22,  Prev: connector-odbc-news-3-51-24,  Up: connector-odbc-news

C.4.23 Changes in MySQL Connector/ODBC 3.51.23 (09 January 2008)
----------------------------------------------------------------

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * There are no installer packages for Microsoft Windows x64 Edition.

Bugs fixed:

   * Connector/ODBC would incorrectly return `SQL_SUCCESS' when
     checking for distributed transaction support.  (Bug#32727
     (http://bugs.mysql.com/32727))

   * When using unixODBC or directly linked applications where the
     thread level is set to less than 3 (within `odbcinst.ini'), a
     thread synchronization issue would lead to an application crash.
     This was because `SQLAllocStmt()' and `SQLFreeStmt()' did not
     synchronize access to the list of statements associated with a
     connection.  (Bug#32587 (http://bugs.mysql.com/32587))

   * Cleaning up environment handles in multithread environments could
     result in a five (or more) second delay.  (Bug#32366
     (http://bugs.mysql.com/32366))

   * Renaming an existing DSN entry would create a new entry with the
     new name without deleting the old entry.  (Bug#31165
     (http://bugs.mysql.com/31165))

   * Setting the default database using the `DefaultDatabase' property
     of an ADO `Connection' object would fail with the error `Provider
     does not support this property'. The `SQLGetInfo()' returned the
     wrong value for `SQL_DATABASE_NAME' when no database was selected.
     (Bug#3780 (http://bugs.mysql.com/3780))


File: manual.info,  Node: connector-odbc-news-3-51-22,  Next: connector-odbc-news-3-51-21,  Prev: connector-odbc-news-3-51-23,  Up: connector-odbc-news

C.4.24 Changes in MySQL Connector/ODBC 3.51.22 (13 November 2007)
-----------------------------------------------------------------

Functionality added or changed:

   * The workaround for this bug was removed due to the fixes in MySQL
     Server 5.0.48 and 5.1.21.

     This regression was introduced by Bug#10491
     (http://bugs.mysql.com/10491).

Bugs fixed:

   * The `English' locale would be used when formatting floating point
     values. The `C' locale is now used for these values.  (Bug#32294
     (http://bugs.mysql.com/32294))

   * When accessing information about supported operations, the driver
     would return incorrect information about the support for *Note
     `UNION': union.  (Bug#32253 (http://bugs.mysql.com/32253))

   * Unsigned integer values greater than the maximum value of a signed
     integer would be handled incorrectly.  (Bug#32171
     (http://bugs.mysql.com/32171))

   * The wrong result was returned by `SQLGetData()' when the data was
     an empty string and a zero-sized buffer was specified.  (Bug#30958
     (http://bugs.mysql.com/30958))

   * Added the `FLAG_COLUMN_SIZE_S32' option to limit the reported
     column size to a signed 32-bit integer. This option is
     automatically enabled for ADO applications to provide a work
     around for a bug in ADO.  (Bug#13776 (http://bugs.mysql.com/13776))


File: manual.info,  Node: connector-odbc-news-3-51-21,  Next: connector-odbc-news-3-51-20,  Prev: connector-odbc-news-3-51-22,  Up: connector-odbc-news

C.4.25 Changes in MySQL Connector/ODBC 3.51.21 (08 October 2007)
----------------------------------------------------------------

Bugs fixed:

   * When using a rowset/cursor and add a new row with a number of
     fields, subsequent rows with fewer fields will include the
     original fields from the previous row in the final *Note `INSERT':
     insert. statement.  (Bug#31246 (http://bugs.mysql.com/31246))

   * Uninitiated memory could be used when C/ODBC internally calls
     `SQLGetFunctions()'.  (Bug#31055 (http://bugs.mysql.com/31055))

   * The wrong `SQL_DESC_LITERAL_PREFIX' would be returned for
     date/time types.  (Bug#31009 (http://bugs.mysql.com/31009))

   * The wrong `COLUMN_SIZE' would be returned by `SQLGetTypeInfo' for
     the TIME columns (`SQL_TYPE_TIME').  (Bug#30939
     (http://bugs.mysql.com/30939))

   * Clicking outside the character set selection box when configuring
     a new DSN could cause the wrong character set to be selected.
     (Bug#30568 (http://bugs.mysql.com/30568))

   * Not specifying a user in the DSN dialog would raise a warning even
     though the parameter is optional.  (Bug#30499
     (http://bugs.mysql.com/30499))

   * `SQLSetParam()' caused memory allocation errors due to driver
     manager's mapping of deprecated functions (buffer length -1).
     (Bug#29871 (http://bugs.mysql.com/29871))

   * When using ADO, a column marked as `AUTO_INCREMENT' could
     incorrectly report that the column allowed `NULL' values. This was
     dur to an issue with `NULLABLE' and `IS_NULLABLE' return values
     from the call to `SQLColumns()'.  (Bug#26108
     (http://bugs.mysql.com/26108))

   * Connector/ODBC would return the wrong the error code when the
     server disconnects the active connection because the configured
     `wait_timeout' has expired.  Previously it would return `HY000'.
     Connector/ODBC now correctly returns an `SQLSTATE' of `08S01'.
     (Bug#3456 (http://bugs.mysql.com/3456))


File: manual.info,  Node: connector-odbc-news-3-51-20,  Next: connector-odbc-news-3-51-19,  Prev: connector-odbc-news-3-51-21,  Up: connector-odbc-news

C.4.26 Changes in MySQL Connector/ODBC 3.51.20 (10 September 2007)
------------------------------------------------------------------

Bugs fixed:

   * Using `FLAG_NO_PROMPT' doesn't suppress the dialogs normally
     handled by `SQLDriverConnect'.  (Bug#30840
     (http://bugs.mysql.com/30840))

   * The specified length of the user name and authentication
     parameters to `SQLConnect()' were not being honored.  (Bug#30774
     (http://bugs.mysql.com/30774))

   * The wrong column size was returned for binary data.  (Bug#30547
     (http://bugs.mysql.com/30547))

   * `SQLGetData()' will now always return `SQL_NO_DATA_FOUND' on
     second call when no data left, even if requested size is 0.
     (Bug#30520 (http://bugs.mysql.com/30520))

   * `SQLGetConnectAttr()' did not reflect the connection state
     correctly.  (Bug#14639 (http://bugs.mysql.com/14639))

   * Removed checkbox in setup dialog for `FLAG_FIELD_LENGTH'
     (identified as `Don't Optimize Column Width' within the GUI
     dialog), which was removed from the driver in 3.51.18.


File: manual.info,  Node: connector-odbc-news-3-51-19,  Next: connector-odbc-news-3-51-18,  Prev: connector-odbc-news-3-51-20,  Up: connector-odbc-news

C.4.27 Changes in MySQL Connector/ODBC 3.51.19 (10 August 2007)
---------------------------------------------------------------

Connector/ODBC 3.51.19 fixes a specific issue with the 3.51.18 release.
For a list of changes in the 3.51.18 release, see *Note
connector-odbc-news-3-51-18::.

Functionality added or changed:

   * Because of Bug#10491 (http://bugs.mysql.com/10491) in the server,
     character string results were sometimes incorrectly identified as
     `SQL_VARBINARY'. Until this server bug is corrected, the driver
     will identify all variable-length strings as `SQL_VARCHAR'.


File: manual.info,  Node: connector-odbc-news-3-51-18,  Next: connector-odbc-news-3-51-17,  Prev: connector-odbc-news-3-51-19,  Up: connector-odbc-news

C.4.28 Changes in MySQL Connector/ODBC 3.51.18 (08 August 2007)
---------------------------------------------------------------

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * Binary packages for Sun Solaris are now available as `PKG'
     packages.

   * Binary packages as disk images with installers are now available
     for Mac OS X.

   * A binary package without an installer is available for Microsoft
     Windows x64 Edition. There are no installer packages for Microsoft
     Windows x64 Edition.

Functionality added or changed:

   * *Incompatible Change*: The `FLAG_DEBUG' option was removed.

   * When connecting to a specific database when using a DSN, the
     system tables from the `mysql' database are no longer also
     available. Previously, tables from the mysql database (catalog)
     were listed as `SYSTEM TABLES' by `SQLTables()' even when a
     different catalog was being queried.  (Bug#28662
     (http://bugs.mysql.com/28662))

   * Installed for Mac OS X has been re-instated. The installer
     registers the driver at a system (not user) level and makes it
     possible to create both user and system DSNs using the
     Connector/ODBC driver. The installer also fixes the situation
     where the necessary drivers would bge installed local to the user,
     not globally.  (Bug#15326 (http://bugs.mysql.com/15326), Bug#10444
     (http://bugs.mysql.com/10444))

   * Connector/ODBC now supports batched statements. In order to enable
     cached statement support you must switch enable the batched
     statement option (`FLAG_MULTI_STATEMENTS', 67108864, or `Allow
     multiple statements' within a GUI configuration). Be aware that
     batched statements create an increased chance of SQL injection
     attacks and you must ensure that your application protects against
     this scenario.  (Bug#7445 (http://bugs.mysql.com/7445))

   * The `SQL_ATTR_ROW_BIND_OFFSET_PTR' is now supported for row bind
     offsets.  (Bug#6741 (http://bugs.mysql.com/6741))

   * The `TRACE' and `TRACEFILE' DSN options have been removed. Use the
     ODBC driver manager trace options instead.

Bugs fixed:

   * When using a table with multiple *Note `TIMESTAMP': datetime.
     columns, the final *Note `TIMESTAMP': datetime. column within the
     table definition would not be updateable. Note that there is still
     a limitation in MySQL server regarding multiple *Note `TIMESTAMP':
     datetime. columns . (Bug#9927 (http://bugs.mysql.com/9927))
     (Bug#30081 (http://bugs.mysql.com/30081))

   * Fixed an issue where the `myodbc3i' would update the user ODBC
     configuration file (`~/Library/ODBC/odbcinst.ini') instead of the
     system `/Library/ODBC/odbcinst.ini'. This was caused because
     `myodbc3i' was not honoring the `s' and `u' modifiers for the `-d'
     command-line option.  (Bug#29964 (http://bugs.mysql.com/29964))

   * Getting table metadata (through the `SQLColumns()' would fail,
     returning a bad table definition to calling applications.
     (Bug#29888 (http://bugs.mysql.com/29888))

   * *Note `DATETIME': datetime. column types would return `FALSE' in
     place of `SQL_SUCCESS' when requesting the column type information.
     (Bug#28657 (http://bugs.mysql.com/28657))

   * The `SQL_COLUMN_TYPE', `SQL_COLUMN_DISPLAY' and
     `SQL_COLUMN_PRECISION' values would be returned incorrectly by
     `SQLColumns()', `SQLDescribeCol()' and `SQLColAttribute()' when
     accessing character columns, especially those generated through
     `concat()'. The lengths returned should now conform to the ODBC
     specification. The `FLAG_FIELD_LENGTH' option no longer has any
     affect on the results returned.  (Bug#27862
     (http://bugs.mysql.com/27862))

   * Obtaining the length of a column when using a character set for
     the connection of `utf8' would result in the length being returned
     incorrectly.  (Bug#19345 (http://bugs.mysql.com/19345))

   * The `SQLColumns()' function could return incorrect information
     about *Note `TIMESTAMP': datetime. columns, indicating that the
     field was not nullable.  (Bug#14414 (http://bugs.mysql.com/14414))

   * The `SQLColumns()' function could return incorrect information
     about `AUTO_INCREMENT' columns, indicating that the field was not
     nullable.  (Bug#14407 (http://bugs.mysql.com/14407))

   * A binary package without an installer is available for Microsoft
     Windows x64 Edition. There are no installer packages for Microsoft
     Windows x64 Edition.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * `BIT(n)' columns are now treated as `SQL_BIT' data where `n = 1'
     and binary data where `n > 1'.

   * The wrong value from `SQL_DESC_LITERAL_SUFFIX' was returned for
     binary fields.

   * The `SQL_DATETIME_SUB' column in SQLColumns() was not correctly
     set for date and time types.

   * The value for `SQL_DESC_FIXED_PREC_SCALE' was not returned
     correctly for values in MySQL 5.0 and later.

   * The wrong value for `SQL_DESC_TYPE' was returned for date and time
     types.

   * `SQLConnect()' and `SQLDriverConnect()' were rewritten to
     eliminate duplicate code and ensure all options were supported
     using both connection methods.  `SQLDriverConnect()' now only
     requires the setup library to be present when the call requires it.

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * Binary packages as disk images with installers are now available
     for Mac OS X.

   * Binary packages for Sun Solaris are now available as `PKG'
     packages.

   * The wrong value for `DECIMAL_DIGITS' in `SQLColumns()' was
     reported for *Note `FLOAT': numeric-types. and *Note `DOUBLE':
     numeric-types. fields, as well as the wrong value for the scale
     parameter to `SQLDescribeCol()', and the `SQL_DESC_SCALE'
     attribute from `SQLColAttribute()'.

   * The `SQL_DATA_TYPE' column in `SQLColumns()' results did not
     report the correct value for date and time types.


File: manual.info,  Node: connector-odbc-news-3-51-17,  Next: connector-odbc-news-3-51-16,  Prev: connector-odbc-news-3-51-18,  Up: connector-odbc-news

C.4.29 Changes in MySQL Connector/ODBC 3.51.17 (14 July 2007)
-------------------------------------------------------------

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * Binary packages for Sun Solaris are now available as `PKG'
     packages.

   * Binary packages as disk images with installers are now available
     for Mac OS X.

   * A binary package without an installer is available for Microsoft
     Windows x64 Edition. There are no installer packages for Microsoft
     Windows x64 Edition.

Functionality added or changed:

   * It is now possible to specify a different character set as part of
     the DSN or connection string. This must be used instead of the
     `SET NAMES' statement. You can also configure the character set
     value from the GUI configuration.  (Bug#9498
     (http://bugs.mysql.com/9498), Bug#6667
     (http://bugs.mysql.com/6667))

   * Fixed calling convention ptr and wrong free in `myodbc3i', and
     fixed the null terminating (was only one, not two) when writing
     DSN to string.

   * Dis-allow NULL ptr for null indicator when calling SQLGetData() if
     value is null. Now returns SQL_ERROR w/state 22002.

   * The setup library has been split into its own RPM package, to
     allow installing the driver itself with no GUI dependencies.

Bugs fixed:

   * `myodbc3i' did not correctly format driver info, which could cause
     the installation to fail.  (Bug#29709
     (http://bugs.mysql.com/29709))

   * Connector/ODBC crashed with Crystal Reports due to a rproblem with
     `SQLProcedures()'.  (Bug#28316 (http://bugs.mysql.com/28316))

   * Fixed a problem where the GUI would crash when configuring or
     removing a System or User DSN.  (Bug#27315
     (http://bugs.mysql.com/27315))

   * Fixed error handling of out-of-memory and bad connections in
     catalog functions. This might raise errors in code paths that had
     ignored them in the past.  (Bug#26934
     (http://bugs.mysql.com/26934))

   * For a stored procedure that returns multiple result sets,
     Connector/ODBC returned only the first result set.  (Bug#16817
     (http://bugs.mysql.com/16817))

   * Calling `SQLGetDiagField' with `RecNumber 0, DiagIdentifier NOT 0'
     returned `SQL_ERROR', preventing access to diagnostic header
     fields.  (Bug#16224 (http://bugs.mysql.com/16224))

   * Added a new DSN option (`FLAG_ZERO_DATE_TO_MIN') to retrieve
     `XXXX-00-00' dates as the minimum allowed ODBC date
     (`XXXX-01-01'). Added another option (`FLAG_MIN_DATE_TO_ZERO') to
     mirror this but for bound parameters. `FLAG_MIN_DATE_TO_ZERO' only
     changes `0000-01-01' to `0000-00-00'.  (Bug#13766
     (http://bugs.mysql.com/13766))

   * If there was more than one unique key on a table, the correct
     fields were not used in handling `SQLSetPos()'.  (Bug#10563
     (http://bugs.mysql.com/10563))

   * When inserting a large *Note `BLOB': blob.  field, Connector/ODBC
     would crash due to a memory allocation error.  (Bug#10562
     (http://bugs.mysql.com/10562))

   * The driver was using `mysql_odbc_escape_string()', which does not
     handle the `NO_BACKSLASH_ESCAPES' SQL mode.  Now it uses *Note
     `mysql_real_escape_string()': mysql-real-escape-string, which does.
     (Bug#9498 (http://bugs.mysql.com/9498))

   * `SQLColumns()' did not handle many of its parameters correctly,
     which could lead to incorrect results. The table name argument was
     not handled as a pattern value, and most arguments were not
     escaped correctly when they contained non-alphanumeric characters.
     (Bug#8860 (http://bugs.mysql.com/8860))

   * There are no binary packages for Microsoft Windows x64 Edition.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * Correctly return error if `SQLBindCol' is called with an invalid
     column.

   * Fixed possible crash if `SQLBindCol()' was not called before
     `SQLSetPos()'.

   * The Mac OS X binary packages are only provided as tarballs, there
     is no installer.

   * The binary packages for Sun Solaris are only provided as tarballs,
     not the PKG format.

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.


File: manual.info,  Node: connector-odbc-news-3-51-16,  Next: connector-odbc-news-3-51-15,  Prev: connector-odbc-news-3-51-17,  Up: connector-odbc-news

C.4.30 Changes in MySQL Connector/ODBC 3.51.16 (14 June 2007)
-------------------------------------------------------------

Functionality added or changed:

   * Connector/ODBC now supports using SSL for communication. This is
     not yet exposed in the setup GUI, but must be enabled through
     configuration files or the DSN.  (Bug#12918
     (http://bugs.mysql.com/12918))

Bugs fixed:

   * Calls to SQLNativeSql() could cause stack corruption due to an
     incorrect pointer cast.  (Bug#28758 (http://bugs.mysql.com/28758))

   * Using curors on results sets with multi-column keys could select
     the wrong value.  (Bug#28255 (http://bugs.mysql.com/28255))

   * `SQLForeignKeys' does not escape `_' and `%' in the table name
     arguments.  (Bug#27723 (http://bugs.mysql.com/27723))

   * When using stored procedures, making a *Note `SELECT': select. or
     second stored procedure call after an initial stored procedure
     call, the second statement will fail.  (Bug#27544
     (http://bugs.mysql.com/27544))

   * SQLTables() did not distinguish tables from views.  (Bug#23031
     (http://bugs.mysql.com/23031))

   * Data in *Note `TEXT': blob. columns would fail to be read
     correctly.  (Bug#16917 (http://bugs.mysql.com/16917))

   * Specifying strings as parameters using the `adBSTR' or `adVarWChar'
     types, (`SQL_WVARCHAR' and `SQL_WLONGVARCHAR') would be incorrectly
     quoted.  (Bug#16235 (http://bugs.mysql.com/16235))

   * SQL_WVARCHAR and SQL_WLONGVARCHAR parameters were not properly
     quoted and escaped.  (Bug#16235 (http://bugs.mysql.com/16235))

   * Using `BETWEEN' with date values, the wrong results could be
     returned.  (Bug#15773 (http://bugs.mysql.com/15773))

   * When using the `Don't Cache Results' (option value `1048576') with
     Microsoft Access, the connection will fail using DAO/VisualBasic.
     (Bug#4657 (http://bugs.mysql.com/4657))

   * Return values from `SQLTables()' may be truncated. (Bugs #22797)


File: manual.info,  Node: connector-odbc-news-3-51-15,  Next: connector-odbc-news-3-51-14,  Prev: connector-odbc-news-3-51-16,  Up: connector-odbc-news

C.4.31 Changes in MySQL Connector/ODBC 3.51.15 (07 May 2007)
------------------------------------------------------------

Bugs fixed:

   * Connector/ODBC would incorrectly claim to support
     `SQLProcedureColumns' (by returning true when queried about
     `SQLPROCEDURECOLUMNS' with `SQLGetFunctions'), but this
     functionality is not supported.  (Bug#27591
     (http://bugs.mysql.com/27591))

   * An incorrect transaction isolation level may not be returned when
     accessing the connection attributes.  (Bug#27589
     (http://bugs.mysql.com/27589))

   * Adding a new DSN with the `myodbc3i' utility under AIX would fail.
     (Bug#27220 (http://bugs.mysql.com/27220))

   * When inserting data using bulk statements (through
     `SQLBulkOperations'), the indicators for all rows within the
     insert would not updated correctly.  (Bug#24306
     (http://bugs.mysql.com/24306))

   * Using `SQLProcedures' does not return the database name within the
     returned resultset.  (Bug#23033 (http://bugs.mysql.com/23033))

   * The `SQLTransact()' function did not support an empty connection
     handle.  (Bug#21588 (http://bugs.mysql.com/21588))

   * Using `SQLDriverConnect' instead of `SQLConnect' could cause later
     operations to fail.  (Bug#7912 (http://bugs.mysql.com/7912))

   * When using blobs and parameter replacement in a statement with
     `WHERE CURSOR OF', the SQL is truncated.  (Bug#5853
     (http://bugs.mysql.com/5853))

   * Connector/ODBC would return too many foreign key results when
     accessing tables with similar names.  (Bug#4518
     (http://bugs.mysql.com/4518))


File: manual.info,  Node: connector-odbc-news-3-51-14,  Next: connector-odbc-news-3-51-13,  Prev: connector-odbc-news-3-51-15,  Up: connector-odbc-news

C.4.32 Changes in MySQL Connector/ODBC 3.51.14 (08 March 2007)
--------------------------------------------------------------

Functionality added or changed:

   * Use of `SQL_ATTR_CONNECTION_TIMEOUT' on the server has now been
     disabled. If you attempt to set this attribute on your connection
     the `SQL_SUCCESS_WITH_INFO' will be returned, with an error
     number/string of `HYC00: Optional feature not supported'.
     (Bug#19823 (http://bugs.mysql.com/19823))

   * Added auto is null option to Connector/ODBC option parameters.
     (Bug#10910 (http://bugs.mysql.com/10910))

   * Added auto-reconnect option to Connector/ODBC option parameters.

   * Added support for the `HENV' handlers in `SQLEndTran()'.

Bugs fixed:

   * On 64-bit systems, some types would be incorrectly returned.
     (Bug#26024 (http://bugs.mysql.com/26024))

   * When retrieving *Note `TIME': time. columns, C/ODBC would
     incorrectly interpret the type of the string and could interpret
     it as a *Note `DATE': datetime. type instead.  (Bug#25846
     (http://bugs.mysql.com/25846))

   * Connector/ODBC may insert the wrong parameter values when using
     prepared statements under 64-bit Linux.  (Bug#22446
     (http://bugs.mysql.com/22446))

   * Using Connector/ODBC, with `SQLBindCol' and binding the length to
     the return value from `SQL_LEN_DATA_AT_EXEC' fails with a memory
     allocation error.  (Bug#20547 (http://bugs.mysql.com/20547))

   * Using `DataAdapter', Connector/ODBC may continually consume memory
     when reading the same records within a loop (Windows Server 2003
     SP1/SP2 only).  (Bug#20459 (http://bugs.mysql.com/20459))

   * When retrieving data from columns that have been compressed using
     `COMPRESS()', the retrieved data would be truncated to 8KB.
     (Bug#20208 (http://bugs.mysql.com/20208))

   * The ODBC driver name and version number were incorrectly reported
     by the driver.  (Bug#19740 (http://bugs.mysql.com/19740))

   * A string format exception would be raised when using iODBC,
     Connector/ODBC and the embedded MySQL server.  (Bug#16535
     (http://bugs.mysql.com/16535))

   * The `SQLDriverConnect()' ODBC method did not work with recent
     Connector/ODBC releases.  (Bug#12393 (http://bugs.mysql.com/12393))


File: manual.info,  Node: connector-odbc-news-3-51-13,  Next: connector-odbc-news-3-51-12,  Prev: connector-odbc-news-3-51-14,  Up: connector-odbc-news

C.4.33 Changes in MySQL Connector/ODBC 3.51.13 (Never released)
---------------------------------------------------------------

Connector/ODBC 3.51.13 was an internal implementation and testing
release.


File: manual.info,  Node: connector-odbc-news-3-51-12,  Next: connector-odbc-news-3-51-11,  Prev: connector-odbc-news-3-51-13,  Up: connector-odbc-news

C.4.34 Changes in MySQL Connector/ODBC 3.51.12 (11 February 2005)
-----------------------------------------------------------------

Functionality added or changed:

   * N/A

Bugs fixed:

   * Using stored procedures with ADO, where the `CommandType' has been
     set correctly to `adCmdStoredProc', calls to stored procedures
     would fail.  (Bug#15635 (http://bugs.mysql.com/15635))

   * File DSNs could not be saved.  (Bug#12019
     (http://bugs.mysql.com/12019))

   * `SQLColumns()' returned no information for tables that had a
     column named using a reserved word.  (Bug#9539
     (http://bugs.mysql.com/9539))


File: manual.info,  Node: connector-odbc-news-3-51-11,  Prev: connector-odbc-news-3-51-12,  Up: connector-odbc-news

C.4.35 Changes in MySQL Connector/ODBC 3.51.11 (28 January 2005)
----------------------------------------------------------------

Bugs fixed:

   * `mysql_list_dbcolumns()' and `insert_fields()' were retrieving all
     rows from a table. Fixed the queries generated by these functions
     to return no rows.  (Bug#8198 (http://bugs.mysql.com/8198))

   * `SQLGetTypoInfo()' returned `tinyblob' for `SQL_VARBINARY' and
     nothing for `SQL_BINARY'. Fixed to return `varbinary' for
     `SQL_VARBINARY', `binary' for `SQL_BINARY', and `longblob' for
     `SQL_LONGVARBINARY'.  (Bug#8138 (http://bugs.mysql.com/8138))


File: manual.info,  Node: connector-net-news,  Next: vstudio-plugin-news,  Prev: connector-odbc-news,  Up: news

C.5 MySQL Connector/NET Change History
======================================

* Menu:

* connector-net-news-6-0-3::     Changes in MySQL Connector/NET 6.0.3 (28 April 2009 beta)
* connector-net-news-6-0-2::     Changes in MySQL Connector/NET 6.0.2 (07 April 2009 beta)
* connector-net-news-6-0-1::     Changes in MySQL Connector/NET 6.0.1 (02 April 2009 beta)
* connector-net-news-6-0-0::     Changes in MySQL Connector/NET 6.0.0 (02 March 2009 alpha)
* connector-net-news-5-3-0::     Changes in MySQL Connector/NET 5.3.0 (Not yet released)
* connector-net-news-5-2-6::     Changes in MySQL Connector/NET 5.2.6 (28 April 2009)
* connector-net-news-5-2-5::     Changes in MySQL Connector/NET 5.2.5 (19 November 2008)
* connector-net-news-5-2-4::     Changes in MySQL Connector/NET 5.2.4 (13 November 2008)
* connector-net-news-5-2-3::     Changes in MySQL Connector/NET 5.2.3 (19 August 2008)
* connector-net-news-5-2-2::     Changes in MySQL Connector/NET 5.2.2 (12 May 2008)
* connector-net-news-5-2-1::     Changes in MySQL Connector/NET 5.2.1 (27 February 2008)
* connector-net-news-5-2-0::     Changes in MySQL Connector/NET 5.2.0 (11 February 2008)
* connector-net-news-5-1-8::     Changes in MySQL Connector/NET 5.1.8 (Not yet released)
* connector-net-news-5-1-7::     Changes in MySQL Connector/NET 5.1.7 (21 August 2008)
* connector-net-news-5-1-6::     Changes in MySQL Connector/NET 5.1.6 (12 May 2008)
* connector-net-news-5-1-5::     Changes in MySQL Connector/NET 5.1.5 (Not yet released)
* connector-net-news-5-1-4::     Changes in MySQL Connector/NET 5.1.4 (20 November 2007)
* connector-net-news-5-1-3::     Changes in MySQL Connector/NET 5.1.3 (21 September 2007 beta)
* connector-net-news-5-1-2::     Changes in MySQL Connector/NET 5.1.2 (18 June 2007)
* connector-net-news-5-1-1::     Changes in MySQL Connector/NET 5.1.1 (23 May 2007)
* connector-net-news-5-1-0::     Changes in MySQL Connector/NET 5.1.0 (01 May 2007)
* connector-net-news-5-0-10::    Changes in MySQL Connector/NET 5.0.10 (Not yet released)
* connector-net-news-5-0-9::     Changes in MySQL Connector/NET 5.0.9 (Not yet released)
* connector-net-news-5-0-8::     Changes in MySQL Connector/NET 5.0.8 (21 August 2007)
* connector-net-news-5-0-7::     Changes in MySQL Connector/NET 5.0.7 (18 May 2007)
* connector-net-news-5-0-6::     Changes in MySQL Connector/NET 5.0.6 (22 March 2007)
* connector-net-news-5-0-5::     Changes in MySQL Connector/NET 5.0.5 (07 March 2007)
* connector-net-news-5-0-4::     Changes in MySQL Connector/NET 5.0.4 (Not released)
* connector-net-news-5-0-3::     Changes in MySQL Connector/NET 5.0.3 (05 January 2007)
* connector-net-news-5-0-2::     Changes in MySQL Connector/NET 5.0.2 (06 November 2006)
* connector-net-news-5-0-1::     Changes in MySQL Connector/NET 5.0.1 (01 October 2006)
* connector-net-news-5-0-0::     Changes in MySQL Connector/NET 5.0.0 (08 August 2006)
* connector-net-news-1-0-11::    Changes in MySQL Connector/NET 1.0.11 (Not yet released)
* connector-net-news-1-0-10::    Changes in MySQL Connector/NET 1.0.10 (24 August 2007)
* connector-net-news-1-0-9::     Changes in MySQL Connector/NET 1.0.9 (02 February 2007)
* connector-net-news-1-0-8::     Changes in MySQL Connector/NET 1.0.8 (20 October 2006)
* connector-net-news-1-0-7::     Changes in MySQL Connector/NET 1.0.7 (21 November 2005)
* connector-net-news-1-0-6::     Changes in MySQL Connector/NET 1.0.6 (03 October 2005)
* connector-net-news-1-0-5::     Changes in MySQL Connector/NET 1.0.5 (29 August 2005)
* connector-net-news-1-0-4::     Changes in MySQL Connector/NET 1.0.4 (20 January 2005)
* connector-net-news-1-0-3::     Changes in MySQL Connector/NET 1.0.3 (12 October 2004 gamma)
* connector-net-news-1-0-2::     Changes in MySQL Connector/NET 1.0.2 (15 November 2004 gamma)
* connector-net-news-1-0-1::     Changes in MySQL Connector/NET 1.0.1 (27 October 2004 beta)
* connector-net-news-1-0-0::     Changes in MySQL Connector/NET 1.0.0 (01 September 2004)
* connector-net-0-9-0::          Changes in MySQL Connector/NET Version 0.9.0 (30 August 2004)
* connector-net-news-0-76::      Changes in MySQL Connector/NET Version 0.76
* connector-net-news-0-75::      Changes in MySQL Connector/NET Version 0.75
* connector-net-0-74::           Changes in MySQL Connector/NET Version 0.74
* connector-net-news-0-71::      Changes in MySQL Connector/NET Version 0.71
* connector-net-news-0-70::      Changes in MySQL Connector/NET Version 0.70
* connector-net-news-0-68::      Changes in MySQL Connector/NET Version 0.68
* connector-net-news-0-65::      Changes in MySQL Connector/NET Version 0.65
* connector-net-news-0-60::      Changes in MySQL Connector/NET Version 0.60
* connector-net-news-0-50::      Changes in MySQL Connector/NET Version 0.50


File: manual.info,  Node: connector-net-news-6-0-3,  Next: connector-net-news-6-0-2,  Prev: connector-net-news,  Up: connector-net-news

C.5.1 Changes in MySQL Connector/NET 6.0.3 (28 April 2009 beta)
---------------------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

Functionality added or changed:

   * The `MySqlTokenizer' failed to split fieldnames from values if
     they were not separated by a space. This also happened if the
     string contained certain characters. As a result
     `MySqlCommand.ExecuteNonQuery' raised an index out of range
     exception.

     The resulting errors are illustrated by the following examples.
     Note, the example statements do not have delimiting spaces around
     the `=' operator.

          INSERT INTO anytable SET Text='test--test';

     The tokenizer incorrectly interpreted the value as containing a
     comment.

          UPDATE anytable SET Project='123-456',Text='Can you explain this ?',Duration=15 WHERE
          ID=4711;'

     A `MySqlException' was generated, as the `?' in the value was
     interpreted by the tokenizer as a parameter sign. The error
     message generated was:

          Fatal error encountered during command execution.
          EXCEPTION: MySqlException - Parameter '?'' must be defined.

     (Bug#44318 (http://bugs.mysql.com/44318))

Bugs fixed:

   * `MySQL.Data' was not displayed as a Reference inside Microsoft
     Visual Studio 2008 Professional.

     When a new C# project was created in Microsoft Visual Studio 2008
     Professional, `MySQL.Data' was not displayed when `References',
     `Add Reference' was selected.  (Bug#44141
     (http://bugs.mysql.com/44141))

   * Column types for `SchemaProvider' and `ISSchemaProvider' did not
     match.

     When the source code in `SchemaProvider.cs' and
     `ISSchemaProvider.cs' were compared it was apparent that they were
     not using the same column types. The base provider used SQL such
     as `SHOW CREATE TABLE', while `ISSchemaProvider' used the schema
     information tables. Column types used by the base class were
     `INT64' and the column types used by `ISSchemaProvider' were
     `UNSIGNED'.  (Bug#44123 (http://bugs.mysql.com/44123))


File: manual.info,  Node: connector-net-news-6-0-2,  Next: connector-net-news-6-0-1,  Prev: connector-net-news-6-0-3,  Up: connector-net-news

C.5.2 Changes in MySQL Connector/NET 6.0.2 (07 April 2009 beta)
---------------------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

Bugs fixed:

   * Connector/Net 6.0.1 did not load in Microsoft Visual Studio 2008
     and Visual Studio 2005 Pro.

     The following error message was generated:

          .NET Framework Data Provider for MySQL: The data provider object factory service was not
          found.

     (Bug#44064 (http://bugs.mysql.com/44064))


File: manual.info,  Node: connector-net-news-6-0-1,  Next: connector-net-news-6-0-0,  Prev: connector-net-news-6-0-2,  Up: connector-net-news

C.5.3 Changes in MySQL Connector/NET 6.0.1 (02 April 2009 beta)
---------------------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

Bugs fixed:

   * An insert and update error was generated by the decimal data type
     in the Entity Framework, when a German collation was used.
     (Bug#43574 (http://bugs.mysql.com/43574))

   * Generating an Entity Data Model (EDM) schema with a table
     containing columns with data types `MEDIUMTEXT' and `LONGTEXT'
     generated a runtime error message `Max value too long or too short
     for Int32'.  (Bug#43480 (http://bugs.mysql.com/43480))


File: manual.info,  Node: connector-net-news-6-0-0,  Next: connector-net-news-5-3-0,  Prev: connector-net-news-6-0-1,  Up: connector-net-news

C.5.4 Changes in MySQL Connector/NET 6.0.0 (02 March 2009 alpha)
----------------------------------------------------------------

This is a new Alpha development release.

Bugs fixed:

   * A null reference exception was generated when
     `MySqlConnection.ClearPool(connection)' was called.  (Bug#42801
     (http://bugs.mysql.com/42801))


File: manual.info,  Node: connector-net-news-5-3-0,  Next: connector-net-news-5-2-6,  Prev: connector-net-news-6-0-0,  Up: connector-net-news

C.5.5 Changes in MySQL Connector/NET 5.3.0 (Not yet released)
-------------------------------------------------------------

Bugs fixed:

   * The Web Provider did not work at all on a remote host, and did not
     create a database when using `autogenerateschema="true"'.
     (Bug#39072 (http://bugs.mysql.com/39072))

   * The Connector/NET installer program ended prematurely without
     reporting the specific error.  (Bug#39019
     (http://bugs.mysql.com/39019))

   * When called with an incorrect password the
     MembershipProvider.GetPassword() method threw a MySQLException
     instead of a MembershipPasswordException .  (Bug#38939
     (http://bugs.mysql.com/38939))

   * Possible overflow in MySqlPacket.ReadLong().  (Bug#36997
     (http://bugs.mysql.com/36997))

   * The TokenizeSql method was adding query overhead and causing high
     CPU utilization for larger queries.  (Bug#36836
     (http://bugs.mysql.com/36836))


File: manual.info,  Node: connector-net-news-5-2-6,  Next: connector-net-news-5-2-5,  Prev: connector-net-news-5-3-0,  Up: connector-net-news

C.5.6 Changes in MySQL Connector/NET 5.2.6 (28 April 2009)
----------------------------------------------------------

Functionality added or changed:

   * A new connection string option has been added: `use affected
     rows'. When `true' the connection will report changed rows instead
     of found rows.  (Bug#44194 (http://bugs.mysql.com/44194))

Bugs fixed:

   * Calling `GetSchema()' on `Indexes' or `IndexColumns' failed where
     index or column names were restricted.

     In `SchemaProvider.cs', methods `GetIndexes()' and
     `GetIndexColumns()' passed their restrictions directly to
     `GetTables()'. This only worked if the restrictions were no more
     specific than `schemaName' and `tableName'.  If `IndexName' was
     given, this was passed to `GetTables()' where it was treated as
     `TableType'. As a result no tables were returned, unless the index
     name happened to be `BASE TABLE' or `VIEW'. This meant that both
     methods failed to return any rows.  (Bug#43991
     (http://bugs.mysql.com/43991))

   * `GetSchema("MetaDataCollections")' should have returned a table
     with a column named `NumberOfRestrictions' not
     `NumberOfRestriction'.

     This can be confirmed by referencing the Microsoft Documentation
     (http://msdn.microsoft.com/en-us/library/system.data.common.dbmetadatacolumnnames.numberofrestrictions.aspx).
     (Bug#43990 (http://bugs.mysql.com/43990))

   * Requests sent to the Connector/NET role provider to remove a user
     from a role failed. The query log showed the query was correctly
     executed within a transaction which was immediately rolled back.
     The rollback was caused by a missing call to the `Complete' method
     of the transaction.  (Bug#43553 (http://bugs.mysql.com/43553))

   * When using `MySqlBulkLoader.Load()', the text file is opened by
     `NativeDriver.SendFileToServer'. If it encountered a problem
     opening the file as a stream, an exception was generated and
     caught. An attempt to clean up resources was then made in the
     `finally{}' clause by calling `fs.Close()', but since the stream
     was never successfully opened, this was an attempt to execute a
     method of a null reference.  (Bug#43332
     (http://bugs.mysql.com/43332))

   * A null reference exception was generated when
     `MySqlConnection.ClearPool(connection)' was called.  (Bug#42801
     (http://bugs.mysql.com/42801))

   * `MySQLMembershipProvider.ValidateUser' only used the `userId' to
     validate. However, it should also use the `applicationId' to
     perform the validation correctly.

     The generated query was, for example:

          SELECT Password, PasswordKey, PasswordFormat, IsApproved, Islockedout
          FROM my_aspnet_Membership WHERE userId=13

     Note that `applicationId' is not used.  (Bug#42574
     (http://bugs.mysql.com/42574))

   * There was an error in the `ProfileProvider' class in the `private
     ProfileInfoCollection GetProfiles()' function. The column of the
     final table was named `lastUpdatdDate' ('e' is missing) instead of
     the correct `lastUpdatedDate'.  (Bug#41654
     (http://bugs.mysql.com/41654))

   * The GetGuid() method of MySqlDataReader did not treat `BINARY(16)'
     column data as a GUID. When operating on such a column a
     `FormatException' exception was generated.  (Bug#41452
     (http://bugs.mysql.com/41452))

   * When ASP.NET membership was configured to not require password
     question and answer using `requiresQuestionAndAnswer="false"', a
     `SqlNullValueException' was generated when using
     `MembershipUser.ResetPassword()' to reset the user password.
     (Bug#41408 (http://bugs.mysql.com/41408))

   * If a `Stored Procedure' contained spaces in its parameter list,
     and was then called from Connector/NET, an exception was
     generated. However, the same `Stored Procedure' called from the
     MySQL Query Analyzer or the MySQL Client worked correctly.

     The exception generated was:

          Parameter '0' not found in the collection.

     (Bug#41034 (http://bugs.mysql.com/41034))

   * The `DATETIME' format contained an erroneous space.  (Bug#41021
     (http://bugs.mysql.com/41021))

   * When `MySql.Web.Profile.MySQLProfileProvider' was configured, it
     was not possible to assign a name other than the default name
     `MySQLProfileProvider'.

     If the name `SCC_MySQLProfileProvider' was assigned, an exception
     was generated when attempting to use `Page.Context.Profile['custom
     prop']'.

     The exception generated was:

          The profile default provider was not found.

     Note that the exception stated: 'the profile *default
     provider*...', even though a different name was explicitly
     requested.  (Bug#40871 (http://bugs.mysql.com/40871))

   * When `ExecuteNonQuery' was called with a command type of `Stored
     Procedure' it worked for one user but resulted in a hang for
     another user with the same database permissions.

     However, if `CALL' was used in the command text and
     `ExecuteNonQuery' was used with a command type of `Text', the call
     worked for both users.  (Bug#40139 (http://bugs.mysql.com/40139))


File: manual.info,  Node: connector-net-news-5-2-5,  Next: connector-net-news-5-2-4,  Prev: connector-net-news-5-2-6,  Up: connector-net-news

C.5.7 Changes in MySQL Connector/NET 5.2.5 (19 November 2008)
-------------------------------------------------------------

Bugs fixed:

   * Visual Studio 2008 displayed the following error three times on
     start-up:

          "Package Load Failure

          Package 'MySql.Data.VisualStudio.MySqlDataProviderPackage, MySql.VisualStudio,
          Version=5.2.4, Culture=neutral, PublicKeyTopen=null' has failed to load properly (GUID =
          {79A115C9-B133-4891-9E7B-242509DAD272}).  Please contact the package vendor for
          assistance.  Application restart is recommended, due to possible environment corruption.
          Would you like to disable loading the package in the future?  You may use
          'devenve/resetskippkgs' to re-enable package loading."

     (Bug#40726 (http://bugs.mysql.com/40726))


File: manual.info,  Node: connector-net-news-5-2-4,  Next: connector-net-news-5-2-3,  Prev: connector-net-news-5-2-5,  Up: connector-net-news

C.5.8 Changes in MySQL Connector/NET 5.2.4 (13 November 2008)
-------------------------------------------------------------

Bugs fixed:

   * `MySqlDataReader' did not feature a `GetSByte' method.  (Bug#40571
     (http://bugs.mysql.com/40571))

   * When working with stored procedures Connector/NET generated an
     exception `Unknown "table parameters" in information_schema'.
     (Bug#40382 (http://bugs.mysql.com/40382))

   * `GetDefaultCollation' and `GetMaxLength' were not thread safe.
     These functions called the database to get a set of parameters and
     cached them in two static dictionaries in the function
     `InitCollections'. However, if many threads called them they would
     try to insert the same keys in the collections resulting in
     duplicate key exceptions.  (Bug#40231
     (http://bugs.mysql.com/40231))

   * If connection pooling was not set explicitly in the connection
     string, Connector/NET added `;Pooling=False' to the end of the
     connection string when `MySqlCommand.ExecuteReader()' was called.

     If connection pooling was explicitly set in the connection string,
     when `MySqlConnection.Open()' was called it converted
     `Pooling=True' to `pooling=True'.

     If `MySqlCommand.ExecuteReader()' was subsequently called, it
     concatenated `;Pooling=False' to the end of the connection string.
     The resulting connection string was thus terminated with
     `pooling=True;Pooling=False'. This disabled connection pooling
     completely.  (Bug#40091 (http://bugs.mysql.com/40091))

   * The connection string option `Functions Return String' did not set
     the correct encoding for the result string. Even though the
     connection string option `Functions Return String=true;' is set,
     the result of `SELECT DES_DECRYPT()' contained `??' instead of the
     correct national character symbols.  (Bug#40076
     (http://bugs.mysql.com/40076))

   * If, when using the MySqlTransaction transaction object, an
     exception was thrown, the transaction object was not disposed of
     and the transaction was not rolled back.  (Bug#39817
     (http://bugs.mysql.com/39817))

   * After the `ConnectionString' property was initialized via the
     public setter of DbConnectionStringBuilder, the
     GetConnectionString method of MySqlConnectionStringBuilder
     incorrectly returned `null' when `true' was assigned to the
     `includePass' parameter.  (Bug#39728 (http://bugs.mysql.com/39728))

   * When using ProfileProvider, attempting to update a previously
     saved property failed.  (Bug#39330 (http://bugs.mysql.com/39330))

   * Reading a negative time value greater than -01:00:00 returned the
     absolute value of the original time value.  (Bug#39294
     (http://bugs.mysql.com/39294))

   * Inserting a negative time value (negative `TimeSpan') into a `Time'
     column through the use of MySqlParameter caused MySqlException to
     be thrown.  (Bug#39275 (http://bugs.mysql.com/39275))

   * When a data connection was created in the server explorer of
     Visual Studio 2008 Team, an error was generated when trying to
     expand stored procedures that had parameters.

     Also, if `TableAdapter' was right-clicked and then `Add', `Query',
     `Use Existing Stored Procedures' selected, if you then attempted
     to select a stored procedure, the window would close and no error
     message would be displayed.  (Bug#39252
     (http://bugs.mysql.com/39252))

   * The Web Provider did not work at all on a remote host, and did not
     create a database when using `autogenerateschema="true"'.
     (Bug#39072 (http://bugs.mysql.com/39072))

   * Connector/NET called hashed password methods not supported in Mono
     2.0 Preview 2.  (Bug#38895 (http://bugs.mysql.com/38895))


File: manual.info,  Node: connector-net-news-5-2-3,  Next: connector-net-news-5-2-2,  Prev: connector-net-news-5-2-4,  Up: connector-net-news

C.5.9 Changes in MySQL Connector/NET 5.2.3 (19 August 2008)
-----------------------------------------------------------

Functionality added or changed:

   * Error string was returned after a 28000 second `wait_timeout'.
     This has been changed to generate a `ConnectionState.Closed' event.
     (Bug#38119 (http://bugs.mysql.com/38119))

   * Changed how the procedure schema collection is retrieved. If the
     connection string contains ``use procedure bodies=true'' then a
     *Note `SELECT': select. is performed on the `mysql.proc' table
     directly, as this is up to 50 times faster than the current
     Information Schema implementation. If the connection string
     contains ``use procedure bodies=false'', then the Information
     Schema collection is queried.  (Bug#36694
     (http://bugs.mysql.com/36694))

   * Changed how the procedure schema collection is retrieved. If `use
     procedure bodies=true' then the `mysql.proc' table is selected
     directly as this is up to 50 times faster than the current
     `information_schema' implementation. If `use procedure
     bodies=false', then the `information_schema' collection is queried.
     (Bug#36694 (http://bugs.mysql.com/36694))

   * String escaping functionality has been moved from the MySqlString
     class to the MySqlHelper class, where it can be accessed by the
     EscapeString method.  (Bug#36205 (http://bugs.mysql.com/36205))

Bugs fixed:

   * The GetOrdinal() method failed to return the ordinal if the column
     name string contained an accent.  (Bug#38721
     (http://bugs.mysql.com/38721))

   * Connector/Net uninstaller did not clean up all installed files.
     (Bug#38534 (http://bugs.mysql.com/38534))

   * There was a short circuit evaluation error in the
     MySqlCommand.CheckState() method. When the statement `connection
     == null' was true a NullReferenceException was thrown and not the
     expected InvalidOperationException.  (Bug#38276
     (http://bugs.mysql.com/38276))

   * The provider did not silently create the user if the user did not
     exist.  (Bug#38243 (http://bugs.mysql.com/38243))

   * Executing a command that resulted in a fatal exception did not
     close the connection.  (Bug#37991 (http://bugs.mysql.com/37991))

   * When a prepared insert query is run that contains an `UNSIGNED
     TINYINT' in the parameter list, the complete query and data that
     should be inserted is corrupted and no error is thrown.
     (Bug#37968 (http://bugs.mysql.com/37968))

   * In a .NET application MySQL Connector/NET modifies the connection
     string so that it contains several occurrences of the same option
     with different values. This is illustrated by the example that
     follows.

     The original connection string:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25; auto enlist=false;pooling=false;

     The connection string after after closing MySqlDataReader:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25;auto enlist=false;pooling=false;
            Allow User Variables=True;Allow User Variables=False;
            Allow User Variables=True;Allow User Variables=False;

     (Bug#37955 (http://bugs.mysql.com/37955))

   * Unnecessary network traffic was generated for the normal case
     where the web provider schema was up to date.  (Bug#37469
     (http://bugs.mysql.com/37469))

   * MySqlReader.GetOrdinal() performance enhancements break existing
     functionality.  (Bug#37239 (http://bugs.mysql.com/37239))

   * The `autogenerateschema' option produced tables with incorrect
     collations.  (Bug#36444 (http://bugs.mysql.com/36444))

   * GetSchema did not work correctly when querying for a collection,
     if using a non-English locale.  (Bug#35459
     (http://bugs.mysql.com/35459))

   * When reading back a stored double or single value using the .NET
     provider, the value had less precision than the one stored.
     (Bug#33322 (http://bugs.mysql.com/33322))

   * Using the MySQL Visual Studio plugin and a MySQL 4.1 server,
     certain field types (*Note `ENUM': enum.) would not be identified
     correctly. Also, when looking for tables, the plugin would list
     all tables matching a wildcard pattern of the database name
     supplied in the connection string, instead of only tables within
     the specified database.  (Bug#30603 (http://bugs.mysql.com/30603))


File: manual.info,  Node: connector-net-news-5-2-2,  Next: connector-net-news-5-2-1,  Prev: connector-net-news-5-2-3,  Up: connector-net-news

C.5.10 Changes in MySQL Connector/NET 5.2.2 (12 May 2008)
---------------------------------------------------------

Bugs fixed:

   * Product documentation incorrectly stated '?' is the preferred
     parameter marker.  (Bug#37349 (http://bugs.mysql.com/37349))

   * An incorrect value for a bit field would returned in a multi-row
     query if a preceding value for the field returned `NULL'.
     (Bug#36313 (http://bugs.mysql.com/36313))

   * Tables with `GEOMETRY' field types would return an unknown
     datatype exception.  (Bug#36081 (http://bugs.mysql.com/36081))

   * When using the `MySQLProfileProvider', setting profile details and
     then reading back saved data would result in the default values
     being returned instead of the updated values.  (Bug#36000
     (http://bugs.mysql.com/36000))

   * When creating a connection, setting the `ConnectionString'
     property of `MySqlConnection' to `NULL' would throw an exception.
     (Bug#35619 (http://bugs.mysql.com/35619))

   * The DbCommandBuilder.QuoteIdentifer method was not implemented.
     (Bug#35492 (http://bugs.mysql.com/35492))

   * When using encrypted passwords, the `GetPassword()' function would
     return the wrong string.  (Bug#35336 (http://bugs.mysql.com/35336))

   * An error would be raised when calling `GetPassword()' with a `NULL'
     value.  (Bug#35332 (http://bugs.mysql.com/35332))

   * When retreiving data where a field has been identified as
     containing a GUID value, the incorrect value would be returned
     when a previous row contained a `NULL' value for that field.
     (Bug#35041 (http://bugs.mysql.com/35041))

   * Using the `TableAdapter Wizard' would fail when generating
     commands that used stored procedures due to the change in
     supported parameter characters.  (Bug#34941
     (http://bugs.mysql.com/34941))

   * When creating a new stored procedured, the new parameter code
     which allows the use of the `@' symbol would interfere with the
     specification of a `DEFINER'.  (Bug#34940
     (http://bugs.mysql.com/34940))

   * When using `SqlDataSource' to open a connection, the connection
     would not automatically be closed when access had completed.
     (Bug#34460 (http://bugs.mysql.com/34460))

   * There was a high level of contention in the connection pooling
     code that could lead to delays when opening connections and
     submitting queries. The connection pooling code has been modified
     to try and limit the effects of the contention issue.  (Bug#34001
     (http://bugs.mysql.com/34001))

   * Using the `TableAdaptor' wizard in combination with a suitable
     *Note `SELECT': select. statement, only the associated *Note
     `INSERT': insert.  statement would also be created, rather than
     the required *Note `DELETE': delete. and *Note `UPDATE': update.
     statements.  (Bug#31338 (http://bugs.mysql.com/31338))

   * Fixed problem in datagrid code related to creating a new table.
     This problem may have been introduced with .NET 2.0 SP1.

   * Fixed profile provider that would throw an exception if you were
     updating a profile that already existed.


File: manual.info,  Node: connector-net-news-5-2-1,  Next: connector-net-news-5-2-0,  Prev: connector-net-news-5-2-2,  Up: connector-net-news

C.5.11 Changes in MySQL Connector/NET 5.2.1 (27 February 2008)
--------------------------------------------------------------

Bugs fixed:

   * When using the provider to generate or update users and passwords,
     the password checking algorithm would not validate the password
     strength or requirements correctly.  (Bug#34792
     (http://bugs.mysql.com/34792))

   * When executing statements that used stored procedures and
     functions, the new parameter code could fail to identify the
     correct parameter format.  (Bug#34699
     (http://bugs.mysql.com/34699))

   * The installer would fail to the DDEX provider binary if the Visual
     Studio 2005 component was not selected. The result would lead to
     Connector/NET not loading properly when using the interface to a
     MySQL server within Visual Studio.  (Bug#34674
     (http://bugs.mysql.com/34674))

   * A number issues were identified in the case, connection and scema
     areas of the code for `MembershipProvider', `RoleProvider',
     `ProfileProvider'.  (Bug#34495 (http://bugs.mysql.com/34495))

   * When using web providers, the Connector/NET would check the schema
     and cache the application id, even when the connection string had
     been set. The effect would be to break the memvership provider
     list.  (Bug#34451 (http://bugs.mysql.com/34451))

   * Attempting to use an isolation level other than the default with a
     transaction scope would use the default isolation level.
     (Bug#34448 (http://bugs.mysql.com/34448))

   * When altering a stored procedure within Visual Studio, the
     parameters to the procedure could be lost.  (Bug#34359
     (http://bugs.mysql.com/34359))

   * A race condition could occur within the procedure cache resulting
     the cache contents overflowing beyond the configured cache size.
     (Bug#34338 (http://bugs.mysql.com/34338))

   * Fixed problem with Visual Studio 2008 integration that caused
     pop-up menus on server explorer nodes to not function

   * The provider code has been updated to fix a number of outstanding
     issues.


File: manual.info,  Node: connector-net-news-5-2-0,  Next: connector-net-news-5-1-8,  Prev: connector-net-news-5-2-1,  Up: connector-net-news

C.5.12 Changes in MySQL Connector/NET 5.2.0 (11 February 2008)
--------------------------------------------------------------

Functionality added or changed:

   * Performing `GetValue()' on a field `TINYINT(1)' returned a *Note
     `BOOLEAN': numeric-types. While not a bug, this caused problems in
     software that expected an *Note `INT': numeric-types. to be
     returned. A new connection string option `Treat Tiny As Boolean'
     has been added with a default value of `true'. If set to `false'
     the provider will treat `TINYINT(1)' as *Note `INT': numeric-types.
     (Bug#34052 (http://bugs.mysql.com/34052))

   * Added support for `DbDataAdapter' `UpdateBatchSize'. Batching is
     fully supported including collapsing inserts down into the
     multi-value form if possible.

   * DDEX provider now works under Visual Studio 2008 beta 2.

   * Added ClearPool and ClearAllPools features.

Bugs fixed:

   * Some speed improvements have been implemented in the `TokenizeSql'
     process used to identify elements of SQL statements.  (Bug#34220
     (http://bugs.mysql.com/34220))

   * When accessing tables from different databases within the same
     `TransactionScope', the same user/password combination would be
     used for each database connection.  Connector/NET does not handle
     multiple connections within the same transaction scope. An error
     is now returned if you attempt this process, instead of using the
     incorrect authorization information.  (Bug#34204
     (http://bugs.mysql.com/34204))

   * The status of connections reported through the state change
     handler was not being updated correctly.  (Bug#34082
     (http://bugs.mysql.com/34082))

   * Incorporated some connection string cache optimizations sent to us
     by Maxim Mass.  (Bug#34000 (http://bugs.mysql.com/34000))

   * In an open connection where the server had disconnected
     unexpectedly, the status information of the connection would not
     be updated properly.  (Bug#33909 (http://bugs.mysql.com/33909))

   * Data cached from the connection string could return invalid
     information because the internal routines were not using
     case-sensitive semantics. This lead to updated connection string
     options not being recognized if they were of a different case than
     the existing cached values.  (Bug#31433
     (http://bugs.mysql.com/31433))

   * Column name metadata was not using the character set as deifned
     within the connection string being used.  (Bug#31185
     (http://bugs.mysql.com/31185))

   * Memory usage could increase and decrease significantly when
     updating or inserting a large number of rows.  (Bug#31090
     (http://bugs.mysql.com/31090))

   * Commands executed from within the state change handeler would fail
     with a `NULL' exception.  (Bug#30964 (http://bugs.mysql.com/30964))

   * When running a stored procedure multiple times on the same
     connection, the memory usage could increase indefinitely.
     (Bug#30116 (http://bugs.mysql.com/30116))

   * Using compression in the MySQL connection with Connector/NET would
     be slower than using native (uncompressed) communication.
     (Bug#27865 (http://bugs.mysql.com/27865))

   * The `MySqlDbType.Datetime' has been replaced with
     `MySqlDbType.DateTime'. The old format has been obsoleted.
     (Bug#26344 (http://bugs.mysql.com/26344))


File: manual.info,  Node: connector-net-news-5-1-8,  Next: connector-net-news-5-1-7,  Prev: connector-net-news-5-2-0,  Up: connector-net-news

C.5.13 Changes in MySQL Connector/NET 5.1.8 (Not yet released)
--------------------------------------------------------------

Bugs fixed:

   * Calling `GetSchema()' on `Indexes' or `IndexColumns' failed where
     index or column names were restricted.

     In `SchemaProvider.cs', methods `GetIndexes()' and
     `GetIndexColumns()' passed their restrictions directly to
     `GetTables()'. This only worked if the restrictions were no more
     specific than `schemaName' and `tableName'.  If `IndexName' was
     given, this was passed to `GetTables()' where it was treated as
     `TableType'. As a result no tables were returned, unless the index
     name happened to be `BASE TABLE' or `VIEW'. This meant that both
     methods failed to return any rows.  (Bug#43991
     (http://bugs.mysql.com/43991))

   * The `DATETIME' format contained an erroneous space.  (Bug#41021
     (http://bugs.mysql.com/41021))

   * If connection pooling was not set explicitly in the connection
     string, Connector/NET added `;Pooling=False' to the end of the
     connection string when `MySqlCommand.ExecuteReader()' was called.

     If connection pooling was explicitly set in the connection string,
     when `MySqlConnection.Open()' was called it converted
     `Pooling=True' to `pooling=True'.

     If `MySqlCommand.ExecuteReader()' was subsequently called, it
     concatenated `;Pooling=False' to the end of the connection string.
     The resulting connection string was thus terminated with
     `pooling=True;Pooling=False'. This disabled connection pooling
     completely.  (Bug#40091 (http://bugs.mysql.com/40091))

   * If, when using the MySqlTransaction transaction object, an
     exception was thrown, the transaction object was not disposed of
     and the transaction was not rolled back.  (Bug#39817
     (http://bugs.mysql.com/39817))

   * When a prepared insert query is run that contains an `UNSIGNED
     TINYINT' in the parameter list, the complete query and data that
     should be inserted is corrupted and no error is thrown.
     (Bug#37968 (http://bugs.mysql.com/37968))


File: manual.info,  Node: connector-net-news-5-1-7,  Next: connector-net-news-5-1-6,  Prev: connector-net-news-5-1-8,  Up: connector-net-news

C.5.14 Changes in MySQL Connector/NET 5.1.7 (21 August 2008)
------------------------------------------------------------

Bugs fixed:

   * There was a short circuit evaluation error in the
     MySqlCommand.CheckState() method. When the statement `connection
     == null' was true a NullReferenceException was thrown and not the
     expected InvalidOperationException.  (Bug#38276
     (http://bugs.mysql.com/38276))

   * Executing a command that resulted in a fatal exception did not
     close the connection.  (Bug#37991 (http://bugs.mysql.com/37991))

   * In a .NET application MySQL Connector/NET modifies the connection
     string so that it contains several occurrences of the same option
     with different values. This is illustrated by the example that
     follows.

     The original connection string:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25; auto enlist=false;pooling=false;

     The connection string after after closing MySqlDataReader:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25;auto enlist=false;pooling=false;
            Allow User Variables=True;Allow User Variables=False;
            Allow User Variables=True;Allow User Variables=False;

     (Bug#37955 (http://bugs.mysql.com/37955))

   * As MySqlDbType.DateTime is not available in `VB.Net' the warning
     `The datetime enum value is obsolete' was always shown during
     compilation.  (Bug#37406 (http://bugs.mysql.com/37406))

   * An unknown `MySqlErrorCode' was encountered when opening a
     connection with an incorrect password.  (Bug#37398
     (http://bugs.mysql.com/37398))

   * Documentation incorrectly stated that `the DataColumn class in
     .NET 1.0 and 1.1 does not allow columns with type of UInt16,
     UInt32, or UInt64 to be autoincrement columns'.  (Bug#37350
     (http://bugs.mysql.com/37350))

   * SemaphoreFullException is generated when application is closed.
     (Bug#36688 (http://bugs.mysql.com/36688))

   * GetSchema did not work correctly when querying for a collection,
     if using a non-English locale.  (Bug#35459
     (http://bugs.mysql.com/35459))

   * When reading back a stored double or single value using the .NET
     provider, the value had less precision than the one stored.
     (Bug#33322 (http://bugs.mysql.com/33322))

   * Using the MySQL Visual Studio plugin and a MySQL 4.1 server,
     certain field types (*Note `ENUM': enum.) would not be identified
     correctly. Also, when looking for tables, the plugin would list
     all tables matching a wildcard pattern of the database name
     supplied in the connection string, instead of only tables within
     the specified database.  (Bug#30603 (http://bugs.mysql.com/30603))


File: manual.info,  Node: connector-net-news-5-1-6,  Next: connector-net-news-5-1-5,  Prev: connector-net-news-5-1-7,  Up: connector-net-news

C.5.15 Changes in MySQL Connector/NET 5.1.6 (12 May 2008)
---------------------------------------------------------

Bugs fixed:

   * When creating a connection pool, specifying an invalid IP address
     will cause the entire application to crash, instead of providing
     an exception.  (Bug#36432 (http://bugs.mysql.com/36432))

   * An incorrect value for a bit field would returned in a multi-row
     query if a preceding value for the field returned `NULL'.
     (Bug#36313 (http://bugs.mysql.com/36313))

   * The `MembershipProvider' will raise an exception when the
     connection string is configured with `enablePasswordRetrival =
     true' and `RequireQuestionAndAnswer = false'.  (Bug#36159
     (http://bugs.mysql.com/36159))

   * When calling `GetNumberOfUsersOnline' an exception is raised on
     the submitted query due to a missing parameter.  (Bug#36157
     (http://bugs.mysql.com/36157))

   * Tables with `GEOMETRY' field types would return an unknown
     datatype exception.  (Bug#36081 (http://bugs.mysql.com/36081))

   * When creating a connection, setting the `ConnectionString'
     property of `MySqlConnection' to `NULL' would throw an exception.
     (Bug#35619 (http://bugs.mysql.com/35619))

   * The DbCommandBuilder.QuoteIdentifer method was not implemented.
     (Bug#35492 (http://bugs.mysql.com/35492))

   * When using `SqlDataSource' to open a connection, the connection
     would not automatically be closed when access had completed.
     (Bug#34460 (http://bugs.mysql.com/34460))

   * Attempting to use an isolation level other than the default with a
     transaction scope would use the default isolation level.
     (Bug#34448 (http://bugs.mysql.com/34448))

   * When altering a stored procedure within Visual Studio, the
     parameters to the procedure could be lost.  (Bug#34359
     (http://bugs.mysql.com/34359))

   * A race condition could occur within the procedure cache resulting
     the cache contents overflowing beyond the configured cache size.
     (Bug#34338 (http://bugs.mysql.com/34338))

   * Using the `TableAdaptor' wizard in combination with a suitable
     *Note `SELECT': select. statement, only the associated *Note
     `INSERT': insert.  statement would also be created, rather than
     the required *Note `DELETE': delete. and *Note `UPDATE': update.
     statements.  (Bug#31338 (http://bugs.mysql.com/31338))


File: manual.info,  Node: connector-net-news-5-1-5,  Next: connector-net-news-5-1-4,  Prev: connector-net-news-5-1-6,  Up: connector-net-news

C.5.16 Changes in MySQL Connector/NET 5.1.5 (Not yet released)
--------------------------------------------------------------

Functionality added or changed:

   * Performing `GetValue()' on a field `TINYINT(1)' returned a *Note
     `BOOLEAN': numeric-types. While not a bug, this caused problems in
     software that expected an *Note `INT': numeric-types. to be
     returned. A new connection string option `Treat Tiny As Boolean'
     has been added with a default value of `true'. If set to `false'
     the provider will treat `TINYINT(1)' as *Note `INT': numeric-types.
     (Bug#34052 (http://bugs.mysql.com/34052))

Bugs fixed:

   * Some speed improvements have been implemented in the `TokenizeSql'
     process used to identify elements of SQL statements.  (Bug#34220
     (http://bugs.mysql.com/34220))

   * When accessing tables from different databases within the same
     `TransactionScope', the same user/password combination would be
     used for each database connection.  Connector/NET does not handle
     multiple connections within the same transaction scope. An error
     is now returned if you attempt this process, instead of using the
     incorrect authorization information.  (Bug#34204
     (http://bugs.mysql.com/34204))

   * The status of connections reported through the state change
     handler was not being updated correctly.  (Bug#34082
     (http://bugs.mysql.com/34082))

   * Incorporated some connection string cache optimizations sent to us
     by Maxim Mass.  (Bug#34000 (http://bugs.mysql.com/34000))

   * In an open connection where the server had disconnected
     unexpectedly, the status information of the connection would not
     be updated properly.  (Bug#33909 (http://bugs.mysql.com/33909))

   * Connector/NET would fail to compile properly with `nant'.
     (Bug#33508 (http://bugs.mysql.com/33508))

   * Problem with membership provider would mean that `FindUserByEmail'
     would fail with a `MySqlException' because it was trying to add a
     second parameter with the same name as the first.  (Bug#33347
     (http://bugs.mysql.com/33347))

   * Using compression in the MySQL connection with Connector/NET would
     be slower than using native (uncompressed) communication.
     (Bug#27865 (http://bugs.mysql.com/27865))


File: manual.info,  Node: connector-net-news-5-1-4,  Next: connector-net-news-5-1-3,  Prev: connector-net-news-5-1-5,  Up: connector-net-news

C.5.17 Changes in MySQL Connector/NET 5.1.4 (20 November 2007)
--------------------------------------------------------------

Bugs fixed:

   * Setting the size of a string parameter after the value could cause
     an exception.  (Bug#32094 (http://bugs.mysql.com/32094))

   * Creation of parameter objects with non-input direction using a
     constructor would fail. This was cause by some old legacy code
     preventing their use.  (Bug#32093 (http://bugs.mysql.com/32093))

   * A date string could be returned incorrectly by
     `MySqlDataTime.ToString()' when the date returned by MySQL was
     `0000-00-00 00:00:00'.  (Bug#32010 (http://bugs.mysql.com/32010))

   * A syntax error in a set of batch statements could leave the data
     adapter in a state that appears hung.  (Bug#31930
     (http://bugs.mysql.com/31930))

   * Installing over a failed uninstall of a previous version could
     result in multiple clients being registered in the
     `machine.config'. This would prevent certain aspects of the MySQL
     connection within Visual Studio to work properly.  (Bug#31731
     (http://bugs.mysql.com/31731))

   * Connector/NET would incorrectly report success when enlisting in a
     distributed transaction, although distributed transactions are not
     supported.  (Bug#31703 (http://bugs.mysql.com/31703))

   * Data cached from the connection string could return invalid
     information because the internal routines were not using
     case-sensitive semantics. This lead to updated connection string
     options not being recognized if they were of a different case than
     the existing cached values.  (Bug#31433
     (http://bugs.mysql.com/31433))

   * Trying to use a connection that was not open could return an
     ambiguous and misleading error message.  (Bug#31262
     (http://bugs.mysql.com/31262))

   * Column name metadata was not using the character set as deifned
     within the connection string being used.  (Bug#31185
     (http://bugs.mysql.com/31185))

   * Memory usage could increase and decrease significantly when
     updating or inserting a large number of rows.  (Bug#31090
     (http://bugs.mysql.com/31090))

   * Commands executed from within the state change handeler would fail
     with a `NULL' exception.  (Bug#30964 (http://bugs.mysql.com/30964))

   * Extracting data through XML functions within a query returns the
     data as `System.Byte[]'. This was due to Connector/NET incorrectly
     identifying *Note `BLOB': blob. fields as binary, rather than text.
     (Bug#30233 (http://bugs.mysql.com/30233))

   * When running a stored procedure multiple times on the same
     connection, the memory usage could increase indefinitely.
     (Bug#30116 (http://bugs.mysql.com/30116))

   * Column types with only 1-bit (such as *Note `BOOLEAN':
     numeric-types. and `TINYINT(1)' were not returned as boolean
     fields.  (Bug#27959 (http://bugs.mysql.com/27959))

   * When accessing certain statements, the command would timeout
     before the command completed. Because this cannot always be
     controlled through the individual command timeout options, a
     `default command timeout' has been added to the connection string
     options.  (Bug#27958 (http://bugs.mysql.com/27958))

   * The server error code was not updated in the `Data[]' hash, which
     prevented `DbProviderFactory' users from accessing the server
     error code.  (Bug#27436 (http://bugs.mysql.com/27436))

   * The `MySqlDbType.Datetime' has been replaced with
     `MySqlDbType.DateTime'. The old format has been obsoleted.
     (Bug#26344 (http://bugs.mysql.com/26344))

   * Changing the connection string of a connection to one that changes
     the parameter marker after the connection had been assigned to a
     command but before the connection is opened could cause parameters
     to not be found.  (Bug#13991 (http://bugs.mysql.com/13991))


File: manual.info,  Node: connector-net-news-5-1-3,  Next: connector-net-news-5-1-2,  Prev: connector-net-news-5-1-4,  Up: connector-net-news

C.5.18 Changes in MySQL Connector/NET 5.1.3 (21 September 2007 beta)
--------------------------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

Bugs fixed:

   * An incorrect `ConstraintException' could be raised on an *Note
     `INSERT': insert. when adding rows to a table with a
     multiple-column unique key index.  (Bug#30204
     (http://bugs.mysql.com/30204))

   * A *Note `DATE': datetime. field would be updated with a date/time
     value, causing a `MySqlDataAdapter.Update()' exception.
     (Bug#30077 (http://bugs.mysql.com/30077))

   * The Saudi Hijri calendar was not supported.  (Bug#29931
     (http://bugs.mysql.com/29931))

   * Calling *Note `SHOW CREATE PROCEDURE': show-create-procedure. for
     routines with a hyphen in the catalog name produced a syntax error.
     (Bug#29526 (http://bugs.mysql.com/29526))

   * Connecting to a MySQL server earlier than version 4.1 would raise
     a `NullException'.  (Bug#29476 (http://bugs.mysql.com/29476))

   * The availability of a MySQL server would not be reset when using
     pooled connections (`pooling=true'). This would lead to the server
     being reported as unavailable, even if the server become available
     while the application was still running.  (Bug#29409
     (http://bugs.mysql.com/29409))

   * A `FormatException' error would be raised if a parameter had not
     been found, instead of `Resources.ParameterMustBeDefined'.
     (Bug#29312 (http://bugs.mysql.com/29312))

   * An exception would be thrown when using the Manage Role
     functionality within the web administrator to assign a role to a
     user.  (Bug#29236 (http://bugs.mysql.com/29236))

   * Using the membership/role providers when `validationKey' or
     `decryptionKey' parameters are set to `AutoGenerate', an exception
     would be raised when accessing the corresponding values.
     (Bug#29235 (http://bugs.mysql.com/29235))

   * Certain operations would not check the `UsageAdvisor' setting,
     causing log messages from the Usage Advisor even when it was
     disabled.  (Bug#29124 (http://bugs.mysql.com/29124))

   * Using the same connection string multiple times would result in
     `Database=DBNAME' appearing multiple times in the resulting string.
     (Bug#29123 (http://bugs.mysql.com/29123))

   * _Visual Studio Plugin_: Adding a new query based on a stored
     procedure that uses the *Note `SELECT': select. statement would
     terminate the query/TableAdapter wizard.  (Bug#29098
     (http://bugs.mysql.com/29098))

   * Using `TransactionScope' would cause an
     `InvalidOperationException'.  (Bug#28709
     (http://bugs.mysql.com/28709))


File: manual.info,  Node: connector-net-news-5-1-2,  Next: connector-net-news-5-1-1,  Prev: connector-net-news-5-1-3,  Up: connector-net-news

C.5.19 Changes in MySQL Connector/NET 5.1.2 (18 June 2007)
----------------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

Bugs fixed:

   * Log messages would be truncated to 300 bytes.  (Bug#28706
     (http://bugs.mysql.com/28706))

   * Creating a user would fail due to the application name being set
     incorrectly.  (Bug#28648 (http://bugs.mysql.com/28648))

   * _Visual Studio Plugin_: Adding a new query based on a stored
     procedure that used a *Note `UPDATE': update, *Note `INSERT':
     insert. or *Note `DELETE': delete. statement would terminate the
     query/TableAdapter wizard.  (Bug#28536
     (http://bugs.mysql.com/28536))

   * _Visual Studio Plugin_: Query Builder would fail to show *Note
     `TINYTEXT': blob. columns, and any columns listed after a *Note
     `TINYTEXT': blob. column correctly.  (Bug#28437
     (http://bugs.mysql.com/28437))

   * Accessing the results from a large query when using data
     compression in the connection would fail to return all the data.
     (Bug#28204 (http://bugs.mysql.com/28204))

   * _Visual Studio Plugin_: Update commands would not be generated
     correctly when using the TableAdapter wizard.  (Bug#26347
     (http://bugs.mysql.com/26347))


File: manual.info,  Node: connector-net-news-5-1-1,  Next: connector-net-news-5-1-0,  Prev: connector-net-news-5-1-2,  Up: connector-net-news

C.5.20 Changes in MySQL Connector/NET 5.1.1 (23 May 2007)
---------------------------------------------------------

Bugs fixed:

   * Running the statement *Note `SHOW PROCESSLIST': show-processlist.
     would return columns as byte arrays instead of native columns.
     (Bug#28448 (http://bugs.mysql.com/28448))

   * Installation of the Connector/NET on Windows would fail if
     VisualStudio had not already been installed.  (Bug#28260
     (http://bugs.mysql.com/28260))

   * Connector/NET would look for the wrong table when executing
     `User.IsRole().' (Bug#28251 (http://bugs.mysql.com/28251))

   * Building a connection string within a tight loop would show slow
     performance.  (Bug#28167 (http://bugs.mysql.com/28167))

   * The `UNSIGNED' flag for parameters in a stored procedure would be
     ignored when using `MySqlCommandBuilder' to obtain the parameter
     information.  (Bug#27679 (http://bugs.mysql.com/27679))

   * Using `MySQLDataAdapter.FillSchema()' on a stored procedure would
     raise an exception: `Invalid attempt to access a field before
     calling Read()'.  (Bug#27668 (http://bugs.mysql.com/27668))

   * *Note `DATETIME': datetime. fields from versions of MySQL bgefore
     4.1 would be incorrectly parsed, resulting in a exception.
     (Bug#23342 (http://bugs.mysql.com/23342))

   * Fixed password property on `MySqlConnectionStringBuilder' to use
     `PasswordPropertyText' attribute. This causes dots to show instead
     of actual password text.


File: manual.info,  Node: connector-net-news-5-1-0,  Next: connector-net-news-5-0-10,  Prev: connector-net-news-5-1-1,  Up: connector-net-news

C.5.21 Changes in MySQL Connector/NET 5.1.0 (01 May 2007)
---------------------------------------------------------

Functionality added or changed:

   * Now compiles for .NET CF 2.0.

   * Rewrote stored procedure parsing code using a new SQL tokenizer.
     Really nasty procedures including nested comments are now
     supported.

   * GetSchema will now report objects relative to the currently
     selected database. What this means is that passing in null as a
     database restriction will report objects on the currently selected
     database only.

   * Added Membership and Role provider contributed by Sean Wright
     (thanks!).


File: manual.info,  Node: connector-net-news-5-0-10,  Next: connector-net-news-5-0-9,  Prev: connector-net-news-5-1-0,  Up: connector-net-news

C.5.22 Changes in MySQL Connector/NET 5.0.10 (Not yet released)
---------------------------------------------------------------

Bugs fixed:

   * If, when using the MySqlTransaction transaction object, an
     exception was thrown, the transaction object was not disposed of
     and the transaction was not rolled back.  (Bug#39817
     (http://bugs.mysql.com/39817))

   * Executing a command that resulted in a fatal exception did not
     close the connection.  (Bug#37991 (http://bugs.mysql.com/37991))

   * When a prepared insert query is run that contains an `UNSIGNED
     TINYINT' in the parameter list, the complete query and data that
     should be inserted is corrupted and no error is thrown.
     (Bug#37968 (http://bugs.mysql.com/37968))

   * In a .NET application MySQL Connector/NET modifies the connection
     string so that it contains several occurrences of the same option
     with different values. This is illustrated by the example that
     follows.

     The original connection string:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25; auto enlist=false;pooling=false;

     The connection string after after closing MySqlDataReader:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25;auto enlist=false;pooling=false;
            Allow User Variables=True;Allow User Variables=False;
            Allow User Variables=True;Allow User Variables=False;

     (Bug#37955 (http://bugs.mysql.com/37955))

   * When creating a connection pool, specifying an invalid IP address
     will cause the entire application to crash, instead of providing
     an exception.  (Bug#36432 (http://bugs.mysql.com/36432))

   * GetSchema did not work correctly when querying for a collection,
     if using a non-English locale.  (Bug#35459
     (http://bugs.mysql.com/35459))

   * When reading back a stored double or single value using the .NET
     provider, the value had less precision than the one stored.
     (Bug#33322 (http://bugs.mysql.com/33322))


File: manual.info,  Node: connector-net-news-5-0-9,  Next: connector-net-news-5-0-8,  Prev: connector-net-news-5-0-10,  Up: connector-net-news

C.5.23 Changes in MySQL Connector/NET 5.0.9 (Not yet released)
--------------------------------------------------------------

Bugs fixed:

   * The DbCommandBuilder.QuoteIdentifer method was not implemented.
     (Bug#35492 (http://bugs.mysql.com/35492))

   * Setting the size of a string parameter after the value could cause
     an exception.  (Bug#32094 (http://bugs.mysql.com/32094))

   * Creation of parameter objects with non-input direction using a
     constructor would fail. This was cause by some old legacy code
     preventing their use.  (Bug#32093 (http://bugs.mysql.com/32093))

   * A date string could be returned incorrectly by
     `MySqlDataTime.ToString()' when the date returned by MySQL was
     `0000-00-00 00:00:00'.  (Bug#32010 (http://bugs.mysql.com/32010))

   * A syntax error in a set of batch statements could leave the data
     adapter in a state that appears hung.  (Bug#31930
     (http://bugs.mysql.com/31930))

   * Installing over a failed uninstall of a previous version could
     result in multiple clients being registered in the
     `machine.config'. This would prevent certain aspects of the MySQL
     connection within Visual Studio to work properly.  (Bug#31731
     (http://bugs.mysql.com/31731))

   * Data cached from the connection string could return invalid
     information because the internal routines were not using
     case-sensitive semantics. This lead to updated connection string
     options not being recognized if they were of a different case than
     the existing cached values.  (Bug#31433
     (http://bugs.mysql.com/31433))

   * Column name metadata was not using the character set as deifned
     within the connection string being used.  (Bug#31185
     (http://bugs.mysql.com/31185))

   * Memory usage could increase and decrease significantly when
     updating or inserting a large number of rows.  (Bug#31090
     (http://bugs.mysql.com/31090))

   * Commands executed from within the state change handeler would fail
     with a `NULL' exception.  (Bug#30964 (http://bugs.mysql.com/30964))

   * When running a stored procedure multiple times on the same
     connection, the memory usage could increase indefinitely.
     (Bug#30116 (http://bugs.mysql.com/30116))

   * The server error code was not updated in the `Data[]' hash, which
     prevented `DbProviderFactory' users from accessing the server
     error code.  (Bug#27436 (http://bugs.mysql.com/27436))

   * Changing the connection string of a connection to one that changes
     the parameter marker after the connection had been assigned to a
     command but before the connection is opened could cause parameters
     to not be found.  (Bug#13991 (http://bugs.mysql.com/13991))


File: manual.info,  Node: connector-net-news-5-0-8,  Next: connector-net-news-5-0-7,  Prev: connector-net-news-5-0-9,  Up: connector-net-news

C.5.24 Changes in MySQL Connector/NET 5.0.8 (21 August 2007)
------------------------------------------------------------

*Note*:

This version introduces a new installer technology.

Bugs fixed:

   * Extracting data through XML functions within a query returns the
     data as `System.Byte[]'. This was due to Connector/NET incorrectly
     identifying *Note `BLOB': blob. fields as binary, rather than text.
     (Bug#30233 (http://bugs.mysql.com/30233))

   * An incorrect `ConstraintException' could be raised on an *Note
     `INSERT': insert. when adding rows to a table with a
     multiple-column unique key index.  (Bug#30204
     (http://bugs.mysql.com/30204))

   * A *Note `DATE': datetime. field would be updated with a date/time
     value, causing a `MySqlDataAdapter.Update()' exception.
     (Bug#30077 (http://bugs.mysql.com/30077))

   * Fixed bug where Connector/Net was hand building some date time
     patterns rather than using the patterns provided under
     CultureInfo. This caused problems with some calendars that do not
     support the same ranges as Gregorian..  (Bug#29931
     (http://bugs.mysql.com/29931))

   * Calling *Note `SHOW CREATE PROCEDURE': show-create-procedure. for
     routines with a hyphen in the catalog name produced a syntax error.
     (Bug#29526 (http://bugs.mysql.com/29526))

   * The availability of a MySQL server would not be reset when using
     pooled connections (`pooling=true'). This would lead to the server
     being reported as unavailable, even if the server become available
     while the application was still running.  (Bug#29409
     (http://bugs.mysql.com/29409))

   * A `FormatException' error would be raised if a parameter had not
     been found, instead of `Resources.ParameterMustBeDefined'.
     (Bug#29312 (http://bugs.mysql.com/29312))

   * Certain operations would not check the `UsageAdvisor' setting,
     causing log messages from the Usage Advisor even when it was
     disabled.  (Bug#29124 (http://bugs.mysql.com/29124))

   * Using the same connection string multiple times would result in
     `Database=DBNAME' appearing multiple times in the resulting string.
     (Bug#29123 (http://bugs.mysql.com/29123))

   * Log messages would be truncated to 300 bytes.  (Bug#28706
     (http://bugs.mysql.com/28706))

   * Accessing the results from a large query when using data
     compression in the connection will fail to return all the data.
     (Bug#28204 (http://bugs.mysql.com/28204))

   * Fixed problem where `MySqlConnection.BeginTransaction' checked the
     drivers status var before checking if the connection was open.
     The result was that the driver could report an invalid condition
     on a previously opened connection.

   * Fixed problem where we were not closing prepared statement handles
     when commands are disposed. This could lead to using up all
     prepared statement handles on the server.

   * Fixed the database schema collection so that it works on servers
     that are not properly respecting the `lower_case_table_names'
     setting.

   * Fixed problem where any attempt to not read all the records
     returned from a select where each row of the select is greater
     than 1024 bytes would hang the driver.

   * Fixed problem where a command timing out just after it actually
     finished would cause an exception to be thrown on the command
     timeout thread which would then be seen as an unhandled exception.

   * Fixed some serious issues with command timeout and cancel that
     could present as exceptions about thread ownership. The issue was
     that not all queries cancel the same. Some produce resultsets
     while others don't. ExecuteReader had to be changed to check for
     this.


File: manual.info,  Node: connector-net-news-5-0-7,  Next: connector-net-news-5-0-6,  Prev: connector-net-news-5-0-8,  Up: connector-net-news

C.5.25 Changes in MySQL Connector/NET 5.0.7 (18 May 2007)
---------------------------------------------------------

Bugs fixed:

   * Running the statement *Note `SHOW PROCESSLIST': show-processlist.
     would return columns as byte arrays instead of native columns.
     (Bug#28448 (http://bugs.mysql.com/28448))

   * Building a connection string within a tight loop would show slow
     performance.  (Bug#28167 (http://bugs.mysql.com/28167))

   * Using logging (with the `logging=true' parameter to the connection
     string) would not generate a log file.  (Bug#27765
     (http://bugs.mysql.com/27765))

   * The `UNSIGNED' flag for parameters in a stored procedure would be
     ignored when using `MySqlCommandBuilder' to obtain the parameter
     information.  (Bug#27679 (http://bugs.mysql.com/27679))

   * Using `MySQLDataAdapter.FillSchema()' on a stored procedure would
     raise an exception: `Invalid attempt to access a field before
     calling Read()'.  (Bug#27668 (http://bugs.mysql.com/27668))

   * If you close an open connection with an active transaction, the
     transaction is not automatically rolled back.  (Bug#27289
     (http://bugs.mysql.com/27289))

   * When cloning an open `MySqlClient.MySqlConnection' with the
     `Persist Security Info=False' option set, the cloned connection is
     not usable because the security information has not been cloned.
     (Bug#27269 (http://bugs.mysql.com/27269))

   * Enlisting a null transaction would affect the current connection
     object, such that further enlistment operations to the transaction
     are not possible.  (Bug#26754 (http://bugs.mysql.com/26754))

   * Attempting to change the `Connection Protocol' property within a
     `PropertyGrid' control would raise an exception.  (Bug#26472
     (http://bugs.mysql.com/26472))

   * The `characterset' property would not be identified during a
     connection (also affected Visual Studion Plugin).  (Bug#26147
     (http://bugs.mysql.com/26147), Bug#27240
     (http://bugs.mysql.com/27240))

   * The `CreateFormat' column of the `DataTypes' collection did not
     contain a format specification for creating a new column type.
     (Bug#25947 (http://bugs.mysql.com/25947))

   * *Note `DATETIME': datetime. fields from versions of MySQL bgefore
     4.1 would be incorrectly parsed, resulting in a exception.
     (Bug#23342 (http://bugs.mysql.com/23342))


File: manual.info,  Node: connector-net-news-5-0-6,  Next: connector-net-news-5-0-5,  Prev: connector-net-news-5-0-7,  Up: connector-net-news

C.5.26 Changes in MySQL Connector/NET 5.0.6 (22 March 2007)
-----------------------------------------------------------

Bugs fixed:

   * Publisher listed in "Add/Remove Programs" is not consistent with
     other MySQL products.  (Bug#27253 (http://bugs.mysql.com/27253))

   * `DESCRIBE ....' SQL statement returns byte arrays rather than data
     on MySQL versions older than 4.1.15.  (Bug#27221
     (http://bugs.mysql.com/27221))

   * `cmd.Parameters.RemoveAt("Id")' will cause an error if the last
     item is requested.  (Bug#27187 (http://bugs.mysql.com/27187))

   * `MySqlParameterCollection' and parameters added with `Insert'
     method can not be retrieved later using `ParameterName'.
     (Bug#27135 (http://bugs.mysql.com/27135))

   * Exception thrown when using large values in `UInt64' parameters.
     (Bug#27093 (http://bugs.mysql.com/27093))

   * MySQL Visual Studio Plugin 1.1.2 does not work with Connector/Net
     5.0.5.  (Bug#26960 (http://bugs.mysql.com/26960))


File: manual.info,  Node: connector-net-news-5-0-5,  Next: connector-net-news-5-0-4,  Prev: connector-net-news-5-0-6,  Up: connector-net-news

C.5.27 Changes in MySQL Connector/NET 5.0.5 (07 March 2007)
-----------------------------------------------------------

Functionality added or changed:

   * Reverted behavior that required parameter names to start with the
     parameter marker. We apologize for this back and forth but we
     mistakenly changed the behavior to not match what `SqlClient'
     supports. We now support using either syntax for adding parameters
     however we also respond exactly like `SqlClient' in that if you
     ask for the index of a parameter using a syntax different from
     when you added the parameter, the result will be -1.

   * Assembly now properly appears in the Visual Studio 2005 Add/Remove
     Reference dialog.

   * Fixed problem that prevented use of `SchemaOnly' or `SingleRow'
     command behaviors with stored procedures or prepared statements.

   * Added `MySqlParameterCollection.AddWithValue' and marked the
     `Add(name, value)' method as obsolete.

   * Return parameters created with DeriveParameters now have the name
     `RETURN_VALUE'.

   * Fixed problem with parameter name hashing where the hashes were
     not getting updated when parameters were removed from the
     collection.

   * Fixed problem with calling stored functions when a return
     parameter was not given.

   * Added `Use Procedure Bodies' connection string option to allow
     calling procedures without using procedure metadata.

Bugs fixed:

   * `MySqlConnection.GetSchema' fails with `NullReferenceException'
     for Foreign Keys.  (Bug#26660 (http://bugs.mysql.com/26660))

   * Connector/NET would fail to install under Windows Vista.
     (Bug#26430 (http://bugs.mysql.com/26430))

   * Opening a connection would be slow due to host name lookup.
     (Bug#26152 (http://bugs.mysql.com/26152))

   * Incorrect values/formats would be applied when the `OldSyntax'
     connection string option was used.  (Bug#25950
     (http://bugs.mysql.com/25950))

   * Registry would be incorrectly populated with installation
     locations.  (Bug#25928 (http://bugs.mysql.com/25928))

   * Times with negative values would be returned incorrectly.
     (Bug#25912 (http://bugs.mysql.com/25912))

   * Returned data types of a `DataTypes' collection do not contain the
     right correctl CLR Datatype.  (Bug#25907
     (http://bugs.mysql.com/25907))

   * `GetSchema' and `DataTypes' would throw an exception due to an
     incorrect table name.  (Bug#25906 (http://bugs.mysql.com/25906))

   * `MySqlConnection' throws an exception when connecting to MySQL
     v4.1.7.  (Bug#25726 (http://bugs.mysql.com/25726))

   * *Note `SELECT': select. did not work correctly when using a
     `WHERE' clause containing a UTF-8 string.  (Bug#25651
     (http://bugs.mysql.com/25651))

   * When closing and then re-opening a connection to a database, the
     character set specification is lost.  (Bug#25614
     (http://bugs.mysql.com/25614))

   * Filling a table schema through a stored procedure triggers a
     runtime error.  (Bug#25609 (http://bugs.mysql.com/25609))

   * *Note `BINARY': binary-varbinary. and *Note `VARBINARY':
     binary-varbinary. columns would be returned as a string, not
     binary, datatype.  (Bug#25605 (http://bugs.mysql.com/25605))

   * A critical `ConnectionPool' error would result in repeated
     `System.NullReferenceException'.  (Bug#25603
     (http://bugs.mysql.com/25603))

   * The `UpdateRowSource.FirstReturnedRecord' method does not work.
     (Bug#25569 (http://bugs.mysql.com/25569))

   * When connecting to a MySQL Server earlier than version 4.1, the
     connection would hang when reading data.  (Bug#25458
     (http://bugs.mysql.com/25458))

   * Using `ExecuteScalar()' with more than one query, where one query
     fails, will hang the connection.  (Bug#25443
     (http://bugs.mysql.com/25443))

   * When a `MySqlConversionException' is raised on a remote object,
     the client application would receive a `SerializationException'
     instead.  (Bug#24957 (http://bugs.mysql.com/24957))

   * When connecting to a server, the return code from the connection
     could be zero, even though the host name was incorrect.
     (Bug#24802 (http://bugs.mysql.com/24802))

   * High CPU utilization would be experienced when there is no idle
     connection waiting when using pooled connections through
     `MySqlPool.GetConnection'.  (Bug#24373
     (http://bugs.mysql.com/24373))

   * Connector/NET would not compile properly when used with Mono 1.2.
     (Bug#24263 (http://bugs.mysql.com/24263))

   * Applications would crash when calling with `CommandType' set to
     `StoredProcedure'.


File: manual.info,  Node: connector-net-news-5-0-4,  Next: connector-net-news-5-0-3,  Prev: connector-net-news-5-0-5,  Up: connector-net-news

C.5.28 Changes in MySQL Connector/NET 5.0.4 (Not released)
----------------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.


File: manual.info,  Node: connector-net-news-5-0-3,  Next: connector-net-news-5-0-2,  Prev: connector-net-news-5-0-4,  Up: connector-net-news

C.5.29 Changes in MySQL Connector/NET 5.0.3 (05 January 2007)
-------------------------------------------------------------

Functionality added or changed:

   * Usage Advisor has been implemented. The Usage Advisor checks your
     queries and will report if you are using the connection
     inefficiently.

   * PerfMon hooks have been added to monitor the stored procedure
     cache hits and misses.

   * The `MySqlCommand' object now supports asynchronous query methods.
     This is implemented useg the `BeginExecuteNonQuery' and
     `EndExecuteNonQuery' methods.

   * Metadata from storaed procedures and stored function execution are
     cached.

   * The `CommandBuilder.DeriveParameters' function has been updated to
     the procedure cache.

   * The `ViewColumns' `GetSchema' collection has been updated.

   * Improved speed and performance by re-architecting certain sections
     of the code.

   * Support for the embedded server and client library have been
     removed from this release. Support will be added back to a later
     release.

   * The ShapZipLib library has been replaced with the deflate support
     provided within .NET 2.0.

   * SSL support has been updated.

Bugs fixed:

   * Additional text added to error message (Bug#25178
     (http://bugs.mysql.com/25178))

   * An exception would be raised, or the process would hang, if
     `SELECT' privileges on a database were not granted and a stored
     procedure was used.  (Bug#25033 (http://bugs.mysql.com/25033))

   * When adding parameter objects to a command object, if the
     parameter direction is set to `ReturnValue' before the parameter
     is added to the command object then when the command is executed
     it throws an error.  (Bug#25013 (http://bugs.mysql.com/25013))

   * Using `Driver.IsTooOld()' would return the wrong value.
     (Bug#24661 (http://bugs.mysql.com/24661))

   * When using a `DbNull.Value' as the value for a parameter value,
     and then later setting a specific value type, the command would
     fail with an exception because the wrong type was implied from the
     `DbNull.Value'.  (Bug#24565 (http://bugs.mysql.com/24565))

   * Stored procedure executions are not thread safe.  (Bug#23905
     (http://bugs.mysql.com/23905))

   * Deleting a connection to a disconnected server when using the
     Visual Studio Plugin would cause an assertion failure.  (Bug#23687
     (http://bugs.mysql.com/23687))

   * Nested transactions (which are unsupported)do not raise an error
     or warning.  (Bug#22400 (http://bugs.mysql.com/22400))


File: manual.info,  Node: connector-net-news-5-0-2,  Next: connector-net-news-5-0-1,  Prev: connector-net-news-5-0-3,  Up: connector-net-news

C.5.30 Changes in MySQL Connector/NET 5.0.2 (06 November 2006)
--------------------------------------------------------------

Functionality added or changed:

   * An `Ignore Prepare' option has been added to the connection string
     options. If enabled, prepared statements will be disabled
     application-wide. The default for this option is true.

   * Implemented a stored procedure cache. By default, the connector
     caches the metadata for the last 25 procedures that are seen.  You
     can change the numbver of procedures that are cacheds by using the
     `procedure cache' connection string.

   * *Important change:* Due to a number of issues with the use of
     server-side prepared statements, Connector/NET 5.0.2 has disabled
     their use by default. The disabling of server-side prepared
     statements does not affect the operation of the connector in any
     way.

     To enable server-side prepared statements you must add the
     following configuration property to your connector string
     properties:

          ignore prepare=false

     The default value of this property is true.

Bugs fixed:

   * One system where IPv6 was enabled, Connector/NET would incorrectly
     resolve host names.  (Bug#23758 (http://bugs.mysql.com/23758))

   * Column names with accented characters were not parsed properly
     causing malformed column names in result sets.  (Bug#23657
     (http://bugs.mysql.com/23657))

   * An exception would be thrown when calling `GetSchemaTable' and
     `fields' was null.  (Bug#23538 (http://bugs.mysql.com/23538))

   * A `System.FormatException' exception would be raised when invoking
     a stored procedure with an *Note `ENUM': enum. input parameter.
     (Bug#23268 (http://bugs.mysql.com/23268))

   * During installation, an antivirus error message would be raised
     (indicating a malicious script problem).  (Bug#23245
     (http://bugs.mysql.com/23245))

   * Creating a connection through the Server Explorer when using the
     Visual Studio Plugin would fail. The installer for the Visual
     Studio Plugin has been updated to ensure that Connector/NET 5.0.2
     must be installed.  (Bug#23071 (http://bugs.mysql.com/23071))

   * Using Windows Vista (RC2) as a non-privileged user would raise a
     `Registry key 'Global' access denied'.  (Bug#22882
     (http://bugs.mysql.com/22882))

   * Within Mono, using the `PreparedStatement' interface could result
     in an error due to a `BitArray' copying error.  (Bug#18186
     (http://bugs.mysql.com/18186))

   * Connector/NET did not work as a data source for the
     `SqlDataSource' object used by ASP.NET 2.0.  (Bug#16126
     (http://bugs.mysql.com/16126))


File: manual.info,  Node: connector-net-news-5-0-1,  Next: connector-net-news-5-0-0,  Prev: connector-net-news-5-0-2,  Up: connector-net-news

C.5.31 Changes in MySQL Connector/NET 5.0.1 (01 October 2006)
-------------------------------------------------------------

Bugs fixed:

   * Connector/NET on a Tukish operating system, may fail to execute
     certain SQL statements correctly.  (Bug#22452
     (http://bugs.mysql.com/22452))

   * Starting a transaction on a connection created by
     `MySql.Data.MySqlClient.MySqlClientFactory', using
     `BeginTransaction' without specifying an isolation level, causes
     the SQL statement to fail with a syntax error.  (Bug#22042
     (http://bugs.mysql.com/22042))

   * The `MySqlexception' class is now derived from the `DbException'
     class.  (Bug#21874 (http://bugs.mysql.com/21874))

   * The `#' would not be accepted within column/table names, even
     though it was valid.  (Bug#21521 (http://bugs.mysql.com/21521))

   * You can now install the Connector/NET MSI package from the command
     line using the `/passive', `/quiet', `/q' options.  (Bug#19994
     (http://bugs.mysql.com/19994))

   * Submitting an empty string to a command object through `prepare'
     raises an `System.IndexOutOfRangeException', rather than a
     Connector/Net exception.  (Bug#18391 (http://bugs.mysql.com/18391))

   * Using `ExecuteScalar' with a datetime field, where the value of
     the field is "0000-00-00 00:00:00", a `MySqlConversionException'
     exception would be raised.  (Bug#11991
     (http://bugs.mysql.com/11991))

   * An `MySql.Data.Types.MySqlConversionException' would be raised
     when trying to update a row that contained a date field, where the
     date field contained a zero value (0000-00-00 00:00:00).
     (Bug#9619 (http://bugs.mysql.com/9619))

   * Executing multiple queries as part of a transaction returns `There
     is already an openDataReader associated with this Connection which
     must be closed first'.  (Bug#7248 (http://bugs.mysql.com/7248))

   * Incorrect field/data lengths could be returned for *Note
     `VARCHAR': char. UTF8 columns. Bug (#14592)


File: manual.info,  Node: connector-net-news-5-0-0,  Next: connector-net-news-1-0-11,  Prev: connector-net-news-5-0-1,  Up: connector-net-news

C.5.32 Changes in MySQL Connector/NET 5.0.0 (08 August 2006)
------------------------------------------------------------

Functionality added or changed:

   * Replaced use of ICSharpCode with .NET 2.0 internal deflate support.

   * Refactored test suite to test all protocols in a single pass.

   * Added usage advisor warnings for requesting column values by the
     wrong type.

   * Reimplemented PacketReader/PacketWriter support into MySqlStream
     class.

   * Reworked connection string classes to be simpler and faster.

   * Added procedure metadata caching.

   * Added internal implemention of SHA1 so we don't have to distribute
     the OpenNetCF on mobile devices.

   * Implemented MySqlClientFactory class.

   * Added perfmon hooks for stored procedure cache hits and misses.

   * Implemented classes and interfaces for ADO.Net 2.0 support.

   * Added Async query methods.

   * Implemented Usage Advisor.

   * Completely refactored how column values are handled to avoid
     boxing in some cases.

   * Implemented MySqlConnectionBuilder class.

Bugs fixed:

   * CommandText: Question mark in comment line is being parsed as a
     parameter.  (Bug#6214 (http://bugs.mysql.com/6214))


File: manual.info,  Node: connector-net-news-1-0-11,  Next: connector-net-news-1-0-10,  Prev: connector-net-news-5-0-0,  Up: connector-net-news

C.5.33 Changes in MySQL Connector/NET 1.0.11 (Not yet released)
---------------------------------------------------------------

Bugs fixed:

   * Attempting to utilize MySQL Connector .Net version 1.0.10 throws a
     fatal exception under Mono when pooling is enabled.  (Bug#33682
     (http://bugs.mysql.com/33682))

   * Setting the size of a string parameter after the value could cause
     an exception.  (Bug#32094 (http://bugs.mysql.com/32094))

   * Creation of parameter objects with non-input direction using a
     constructor would fail. This was cause by some old legacy code
     preventing their use.  (Bug#32093 (http://bugs.mysql.com/32093))

   * Memory usage could increase and decrease significantly when
     updating or inserting a large number of rows.  (Bug#31090
     (http://bugs.mysql.com/31090))

   * Commands executed from within the state change handeler would fail
     with a `NULL' exception.  (Bug#30964 (http://bugs.mysql.com/30964))

   * Extracting data through XML functions within a query returns the
     data as `System.Byte[]'. This was due to Connector/NET incorrectly
     identifying *Note `BLOB': blob. fields as binary, rather than text.
     (Bug#30233 (http://bugs.mysql.com/30233))

   * Using compression in the MySQL connection with Connector/NET would
     be slower than using native (uncompressed) communication.
     (Bug#27865 (http://bugs.mysql.com/27865))

   * Changing the connection string of a connection to one that changes
     the parameter marker after the connection had been assigned to a
     command but before the connection is opened could cause parameters
     to not be found.  (Bug#13991 (http://bugs.mysql.com/13991))


File: manual.info,  Node: connector-net-news-1-0-10,  Next: connector-net-news-1-0-9,  Prev: connector-net-news-1-0-11,  Up: connector-net-news

C.5.34 Changes in MySQL Connector/NET 1.0.10 (24 August 2007)
-------------------------------------------------------------

Bugs fixed:

   * An incorrect `ConstraintException' could be raised on an *Note
     `INSERT': insert. when adding rows to a table with a
     multiple-column unique key index.  (Bug#30204
     (http://bugs.mysql.com/30204))

   * The availability of a MySQL server would not be reset when using
     pooled connections (`pooling=true'). This would lead to the server
     being reported as unavailable, even if the server become available
     while the application was still running.  (Bug#29409
     (http://bugs.mysql.com/29409))

   * Publisher listed in "Add/Remove Programs" is not consistent with
     other MySQL products.  (Bug#27253 (http://bugs.mysql.com/27253))

   * `MySqlParameterCollection' and parameters added with `Insert'
     method can not be retrieved later using `ParameterName'.
     (Bug#27135 (http://bugs.mysql.com/27135))

   * *Note `BINARY': binary-varbinary. and *Note `VARBINARY':
     binary-varbinary. columns would be returned as a string, not
     binary, datatype.  (Bug#25605 (http://bugs.mysql.com/25605))

   * A critical `ConnectionPool' error would result in repeated
     `System.NullReferenceException'.  (Bug#25603
     (http://bugs.mysql.com/25603))

   * When a `MySqlConversionException' is raised on a remote object,
     the client application would receive a `SerializationException'
     instead.  (Bug#24957 (http://bugs.mysql.com/24957))

   * High CPU utilization would be experienced when there is no idle
     connection waiting when using pooled connections through
     `MySqlPool.GetConnection'.  (Bug#24373
     (http://bugs.mysql.com/24373))


File: manual.info,  Node: connector-net-news-1-0-9,  Next: connector-net-news-1-0-8,  Prev: connector-net-news-1-0-10,  Up: connector-net-news

C.5.35 Changes in MySQL Connector/NET 1.0.9 (02 February 2007)
--------------------------------------------------------------

Functionality added or changed:

   * The ICSharpCode ZipLib is no longer used by the Connector, and is
     no longer distributed with it.

   * *Important change:* Binaries for .NET 1.0 are no longer supplied
     with this release. If you need support for .NET 1.0, you must
     build from source.

   * Improved `CommandBuilder.DeriveParameters' to first try and use
     the procedure cache before querying for the stored procedure
     metadata. Return parameters created with `DeriveParameters' now
     have the name `RETURN_VALUE'.

   * An `Ignore Prepare' option has been added to the connection string
     options. If enabled, prepared statements will be disabled
     application-wide. The default for this option is true.

   * Implemented a stored procedure cache. By default, the connector
     caches the metadata for the last 25 procedures that are seen.  You
     can change the numbver of procedures that are cacheds by using the
     `procedure cache' connection string.

   * *Important change:* Due to a number of issues with the use of
     server-side prepared statements, Connector/NET 5.0.2 has disabled
     their use by default. The disabling of server-side prepared
     statements does not affect the operation of the connector in any
     way.

     To enable server-side prepared statements you must add the
     following configuration property to your connector string
     properties:

          ignore prepare=false

     The default value of this property is true.

Bugs fixed:

   * Times with negative values would be returned incorrectly.
     (Bug#25912 (http://bugs.mysql.com/25912))

   * `MySqlConnection' throws a `NullReferenceException' and
     `ArgumentNullException' when connecting to MySQL v4.1.7.
     (Bug#25726 (http://bugs.mysql.com/25726))

   * *Note `SELECT': select. did not work correctly when using a
     `WHERE' clause containing a UTF-8 string.  (Bug#25651
     (http://bugs.mysql.com/25651))

   * When closing and then re-opening a connection to a database, the
     character set specification is lost.  (Bug#25614
     (http://bugs.mysql.com/25614))

   * Trying to fill a table schema through a stored procedure triggers
     a runtime error.  (Bug#25609 (http://bugs.mysql.com/25609))

   * Using `ExecuteScalar()' with more than one query, where one query
     fails, will hang the connection.  (Bug#25443
     (http://bugs.mysql.com/25443))

   * Additional text added to error message.  (Bug#25178
     (http://bugs.mysql.com/25178))

   * When adding parameter objects to a command object, if the
     parameter direction is set to `ReturnValue' before the parameter
     is added to the command object then when the command is executed
     it throws an error.  (Bug#25013 (http://bugs.mysql.com/25013))

   * When connecting to a server, the return code from the connection
     could be zero, even though the host name was incorrect.
     (Bug#24802 (http://bugs.mysql.com/24802))

   * Using `Driver.IsTooOld()' would return the wrong value.
     (Bug#24661 (http://bugs.mysql.com/24661))

   * When using a `DbNull.Value' as the value for a parameter value,
     and then later setting a specific value type, the command would
     fail with an exception because the wrong type was implied from the
     `DbNull.Value'.  (Bug#24565 (http://bugs.mysql.com/24565))

   * Stored procedure executions are not thread safe.  (Bug#23905
     (http://bugs.mysql.com/23905))

   * The `CommandBuilder' would mistakenly add insert parameters for a
     table column with auto incrementation enabled.  (Bug#23862
     (http://bugs.mysql.com/23862))

   * One system where IPv6 was enabled, Connector/NET would incorrectly
     resolve host names.  (Bug#23758 (http://bugs.mysql.com/23758))

   * Nested transactions do not raise an error or warning.  (Bug#22400
     (http://bugs.mysql.com/22400))

   * An `System.OverflowException' would be raised when accessing a
     varchar field over 255 bytes. Bug (#23749)

   * Within Mono, using the `PreparedStatement' interface could result
     in an error due to a `BitArray' copying error. (Bug 18186)


File: manual.info,  Node: connector-net-news-1-0-8,  Next: connector-net-news-1-0-7,  Prev: connector-net-news-1-0-9,  Up: connector-net-news

C.5.36 Changes in MySQL Connector/NET 1.0.8 (20 October 2006)
-------------------------------------------------------------

Functionality added or changed:

   * Stored procedures are now cached.

   * The method for retrieving stored procedured metadata has been
     changed so that users without `SELECT' privileges on the
     `mysql.proc' table can use a stored procedure.

Bugs fixed:

   * Connector/NET on a Tukish operating system, may fail to execute
     certain SQL statements correctly.  (Bug#22452
     (http://bugs.mysql.com/22452))

   * The `#' would not be accepted within column/table names, even
     though it was valid.  (Bug#21521 (http://bugs.mysql.com/21521))

   * Calling Close on a connection after calling a stored procedure
     would trigger a `NullReferenceException'.  (Bug#20581
     (http://bugs.mysql.com/20581))

   * You can now install the Connector/NET MSI package from the command
     line using the `/passive', `/quiet', `/q' options.  (Bug#19994
     (http://bugs.mysql.com/19994))

   * The DiscoverParameters function would fail when a stored procedure
     used a *Note `NUMERIC': numeric-types.  parameter type.
     (Bug#19515 (http://bugs.mysql.com/19515))

   * When running a query that included a date comparison, a DateReader
     error would be raised.  (Bug#19481 (http://bugs.mysql.com/19481))

   * `IDataRecord.GetString' would raise `NullPointerException' for
     null values in returned rows. Method now throws
     `SqlNullValueException'.  (Bug#19294 (http://bugs.mysql.com/19294))

   * Parameter substitution in queries where the order of parameters
     and table fields did not match would substitute incorrect values.
     (Bug#19261 (http://bugs.mysql.com/19261))

   * Submitting an empty string to a command object through `prepare'
     raises an `System.IndexOutOfRangeException', rather than a
     Connector/Net exception.  (Bug#18391 (http://bugs.mysql.com/18391))

   * An exception would be raised when using an output parameter to a
     `System.String' value.  (Bug#17814 (http://bugs.mysql.com/17814))

   * CHAR type added to MySqlDbType.  (Bug#17749
     (http://bugs.mysql.com/17749))

   * A *Note `SELECT': select. query on a table with a date with a
     value of `'0000-00-00'' would hang the application.  (Bug#17736
     (http://bugs.mysql.com/17736))

   * The CommandBuilder ignored Unsigned flag at Parameter creation.
     (Bug#17375 (http://bugs.mysql.com/17375))

   * When working with multiple threads, character set initialization
     would generate errors.  (Bug#17106 (http://bugs.mysql.com/17106))

   * When using an unsigned 64-bit integer in a stored procedure, the
     unsigned bit would be lost stored.  (Bug#16934
     (http://bugs.mysql.com/16934))

   * `DataReader' would show the value of the previous row (or last row
     with non-null data) if the current row contained a `datetime'
     field with a null value.  (Bug#16884 (http://bugs.mysql.com/16884))

   * Unsigned data types were not properly supported.  (Bug#16788
     (http://bugs.mysql.com/16788))

   * The connection string parser did not allow single or double quotes
     in the password.  (Bug#16659 (http://bugs.mysql.com/16659))

   * The `MySqlDateTime' class did not contain constructors.
     (Bug#15112 (http://bugs.mysql.com/15112))

   * Called `MySqlCommandBuilder.DeriveParameters' for a stored
     procedure that has no paramers would cause an application crash.
     (Bug#15077 (http://bugs.mysql.com/15077))

   * Using `ExecuteScalar' with a datetime field, where the value of
     the field is "0000-00-00 00:00:00", a `MySqlConversionException'
     exception would be raised.  (Bug#11991
     (http://bugs.mysql.com/11991))

   * An `MySql.Data.Types.MySqlConversionException' would be raised
     when trying to update a row that contained a date field, where the
     date field contained a zero value (0000-00-00 00:00:00).
     (Bug#9619 (http://bugs.mysql.com/9619))

   * When using `MySqlDataAdapter', connections to a MySQL server may
     remain open and active, even though the use of the connection has
     been completed and the data received.  (Bug#8131
     (http://bugs.mysql.com/8131))

   * Executing multiple queries as part of a transaction returns `There
     is already an openDataReader associated with this Connection which
     must be closed first'.  (Bug#7248 (http://bugs.mysql.com/7248))

   * Incorrect field/data lengths could be returned for *Note
     `VARCHAR': char. UTF8 columns. Bug (#14592)


File: manual.info,  Node: connector-net-news-1-0-7,  Next: connector-net-news-1-0-6,  Prev: connector-net-news-1-0-8,  Up: connector-net-news

C.5.37 Changes in MySQL Connector/NET 1.0.7 (21 November 2005)
--------------------------------------------------------------

Bugs fixed:

   * Unsigned `tinyint' (NET byte) would lead to and incorrectly
     determined parameter type from the parameter value.  (Bug#18570
     (http://bugs.mysql.com/18570))

   * A `#42000Query was empty' exception occurred when executing a
     query built with `MySqlCommandBuilder', if the query string ended
     with a semicolon.  (Bug#14631 (http://bugs.mysql.com/14631))

   * The parameter collection object's `Add()' method added parameters
     to the list without first checking to see whether they already
     existed. Now it updates the value of the existing parameter object
     if it exists.  (Bug#13927 (http://bugs.mysql.com/13927))

   * Added support for the `cp932' character set.  (Bug#13806
     (http://bugs.mysql.com/13806))

   * Calling a stored procedure where a parameter contained special
     characters (such as `'@'') would produce an exception. Note that
     `ANSI_QUOTES' had to be enabled to make this possible.  (Bug#13753
     (http://bugs.mysql.com/13753))

   * The `Ping()' method did not update the `State' property of the
     `Connection' object.  (Bug#13658 (http://bugs.mysql.com/13658))

   * Implemented the `MySqlCommandBuilder.DeriveParameters' method that
     is used to discover the parameters for a stored procedure.
     (Bug#13632 (http://bugs.mysql.com/13632))

   * A statement that contained multiple references to the same
     parameter could not be prepared.  (Bug#13541
     (http://bugs.mysql.com/13541))


File: manual.info,  Node: connector-net-news-1-0-6,  Next: connector-net-news-1-0-5,  Prev: connector-net-news-1-0-7,  Up: connector-net-news

C.5.38 Changes in MySQL Connector/NET 1.0.6 (03 October 2005)
-------------------------------------------------------------

Bugs fixed:

   * Connector/NET 1.0.5 could not connect on Mono.  (Bug#13345
     (http://bugs.mysql.com/13345))

   * Serializing a parameter failed if the first value passed in was
     `NULL'.  (Bug#13276 (http://bugs.mysql.com/13276))

   * Field names that contained the following characters caused errors:
     `()%<>/' (Bug#13036 (http://bugs.mysql.com/13036))

   * The `nant' build sequence had problems.  (Bug#12978
     (http://bugs.mysql.com/12978))

   * The Connector/NET 1.0.5 installer would not install alongside
     Connector/NET 1.0.4.  (Bug#12835 (http://bugs.mysql.com/12835))


File: manual.info,  Node: connector-net-news-1-0-5,  Next: connector-net-news-1-0-4,  Prev: connector-net-news-1-0-6,  Up: connector-net-news

C.5.39 Changes in MySQL Connector/NET 1.0.5 (29 August 2005)
------------------------------------------------------------

Bugs fixed:

   * Connector/NET could not connect to MySQL 4.1.14.  (Bug#12771
     (http://bugs.mysql.com/12771))

   * With multiple hosts in the connection string, Connector/NET would
     not connect to the last host in the list.  (Bug#12628
     (http://bugs.mysql.com/12628))

   * The `ConnectionString' property could not be set when a
     `MySqlConnection' object was added with the designer.  (Bug#12551
     (http://bugs.mysql.com/12551), Bug#8724
     (http://bugs.mysql.com/8724))

   * The `cp1250' character set was not supported.  (Bug#11621
     (http://bugs.mysql.com/11621))

   * A call to a stored procedure caused an exception if the stored
     procedure had no parameters.  (Bug#11542
     (http://bugs.mysql.com/11542))

   * Certain malformed queries would trigger a `Connection must be
     valid and open' error message.  (Bug#11490
     (http://bugs.mysql.com/11490))

   * Trying to use a stored procedure when `Connection.Database' was
     not populated generated an exception.  (Bug#11450
     (http://bugs.mysql.com/11450))

   * Connector/NET interpreted the new decimal data type as a byte
     array.  (Bug#11294 (http://bugs.mysql.com/11294))

   * Added support to call a stored function from Connector/NET.
     (Bug#10644 (http://bugs.mysql.com/10644))

   * Connection could fail when .NET thread pool had no available
     worker threads.  (Bug#10637 (http://bugs.mysql.com/10637))

   * Calling `MySqlConnection.clone' when a connection string had not
     yet been set on the original connection would generate an error.
     (Bug#10281 (http://bugs.mysql.com/10281))

   * Decimal parameters caused syntax errors.  (Bug#10152
     (http://bugs.mysql.com/10152), Bug#11550
     (http://bugs.mysql.com/11550), Bug#10486
     (http://bugs.mysql.com/10486))

   * Parameters were not recognized when they were separated by
     linefeeds.  (Bug#9722 (http://bugs.mysql.com/9722))

   * The `MySqlCommandBuilder' class could not handle queries that
     referenced tables in a database other than the default database.
     (Bug#8382 (http://bugs.mysql.com/8382))

   * Trying to read a *Note `TIMESTAMP': datetime. column generated an
     exception.  (Bug#7951 (http://bugs.mysql.com/7951))

   * Connector/NET could not work properly with certain regional
     settings. (WL#8228)


File: manual.info,  Node: connector-net-news-1-0-4,  Next: connector-net-news-1-0-3,  Prev: connector-net-news-1-0-5,  Up: connector-net-news

C.5.40 Changes in MySQL Connector/NET 1.0.4 (20 January 2005)
-------------------------------------------------------------

Bugs fixed:

   * `MySqlReader.GetInt32' throws exception if column is unsigned.
     (Bug#7755 (http://bugs.mysql.com/7755))

   * Quote character \222 not quoted in `EscapeString'.  (Bug#7724
     (http://bugs.mysql.com/7724))

   * GetBytes is working no more.  (Bug#7704
     (http://bugs.mysql.com/7704))

   * `MySqlDataReader.GetString(index)' returns non-Null value when
     field is `Null'.  (Bug#7612 (http://bugs.mysql.com/7612))

   * Clone method bug in `MySqlCommand'.  (Bug#7478
     (http://bugs.mysql.com/7478))

   * Problem with Multiple resultsets.  (Bug#7436
     (http://bugs.mysql.com/7436))

   * `MySqlAdapter.Fill' method throws error message `Non-negative
     number required'.  (Bug#7345 (http://bugs.mysql.com/7345))

   * `MySqlCommand.Connection' returns an IDbConnection.  (Bug#7258
     (http://bugs.mysql.com/7258))

   * Calling prepare causing exception.  (Bug#7243
     (http://bugs.mysql.com/7243))

   * Fixed problem with shared memory connections.

   * Added or filled out several more topics in the API reference
     documentation.

   * Fixed another small problem with prepared statements.

   * Fixed problem that causes named pipes to not work with some blob
     functionality.


File: manual.info,  Node: connector-net-news-1-0-3,  Next: connector-net-news-1-0-2,  Prev: connector-net-news-1-0-4,  Up: connector-net-news

C.5.41 Changes in MySQL Connector/NET 1.0.3 (12 October 2004 gamma)
-------------------------------------------------------------------

Bugs fixed:

   * Invalid query string when using inout parameters (Bug#7133
     (http://bugs.mysql.com/7133))

   * Inserting `DateTime' causes `System.InvalidCastException' to be
     thrown.  (Bug#7132 (http://bugs.mysql.com/7132))

   * `MySqlDateTime' in Datatables sorting by Text, not Date.
     (Bug#7032 (http://bugs.mysql.com/7032))

   * Exception stack trace lost when re-throwing exceptions.  (Bug#6983
     (http://bugs.mysql.com/6983))

   * Errors in parsing stored procedure parameters.  (Bug#6902
     (http://bugs.mysql.com/6902))

   * InvalidCast when using `DATE_ADD'-function.  (Bug#6879
     (http://bugs.mysql.com/6879))

   * Int64 Support in `MySqlCommand' Parameters.  (Bug#6863
     (http://bugs.mysql.com/6863))

   * Test suite fails with MySQL 4.0 because of case sensitivity of
     table names.  (Bug#6831 (http://bugs.mysql.com/6831))

   * `MySqlDataReader.GetChar(int i)' throws `IndexOutOfRange'
     exception.  (Bug#6770 (http://bugs.mysql.com/6770))

   * Integer "out" parameter from stored procedure returned as string.
     (Bug#6668 (http://bugs.mysql.com/6668))

   * An Open Connection has been Closed by the Host System.  (Bug#6634
     (http://bugs.mysql.com/6634))

   * Fixed Invalid character set index: 200.  (Bug#6547
     (http://bugs.mysql.com/6547))

   * Connections now do not have to give a database on the connection
     string.

   * Installer now includes options to install into GAC and create
     `Start Menu' items.

   * Fixed major problem with detecting null values when using prepared
     statements.

   * Fixed problem where multiple resultsets having different numbers
     of columns would cause a problem.

   * Added `ServerThread' property to `MySqlConnection' to expose
     server thread id.

   * Added Ping method to `MySqlConnection'.

   * Changed the name of the test suite to `MySql.Data.Tests.dll'.

   * Now *Note `SHOW COLLATION': show-collation. is used upon
     connection to retrieve the full list of charset ids.

   * Made MySQL the default named pipe name.


File: manual.info,  Node: connector-net-news-1-0-2,  Next: connector-net-news-1-0-1,  Prev: connector-net-news-1-0-3,  Up: connector-net-news

C.5.42 Changes in MySQL Connector/NET 1.0.2 (15 November 2004 gamma)
--------------------------------------------------------------------

Bugs fixed:

   * Fixed Objects not being disposed (Bug#6649
     (http://bugs.mysql.com/6649))

   * Fixed Charset-map for UCS-2 (Bug#6541 (http://bugs.mysql.com/6541))

   * Fixed Zero date "0000-00-00" is returned wrong when filling Dataset
     (Bug#6429 (http://bugs.mysql.com/6429))

   * Fixed double type handling in MySqlParameter(string parameterName,
     object value) (Bug#6428 (http://bugs.mysql.com/6428))

   * Fixed Installation directory ignored using custom installation
     (Bug#6329 (http://bugs.mysql.com/6329))

   * Fixed #HY000 Illegal mix of collations
     (latin1_swedish_ci,IMPLICIT) and (utf8_general_ (Bug#6322
     (http://bugs.mysql.com/6322))

   * Added the TableEditor CS and VB sample

   * Added charset connection string option

   * Fixed problem with MySqlBinary where string values could not be
     used to update extended text columns

   * Provider is now using character set specified by server as default

   * Updated the installer to include the new samples

   * Fixed problem where setting command text leaves the command in a
     prepared state

   * Fixed Long inserts take very long time (Bu #5453)

   * Fixed problem where calling stored procedures might cause an
     "Illegal mix of collations" problem.


File: manual.info,  Node: connector-net-news-1-0-1,  Next: connector-net-news-1-0-0,  Prev: connector-net-news-1-0-2,  Up: connector-net-news

C.5.43 Changes in MySQL Connector/NET 1.0.1 (27 October 2004 beta)
------------------------------------------------------------------

Bugs fixed:

   * Fixed IndexOutOfBounds when reading BLOB with DataReader with
     GetString(index) (Bug#6230 (http://bugs.mysql.com/6230))

   * Fixed GetBoolean returns wrong values (Bug#6227
     (http://bugs.mysql.com/6227))

   * Fixed Method TokenizeSql() uses only a limited set of valid
     characters for parameters (Bug#6217 (http://bugs.mysql.com/6217))

   * Fixed NET Connector source missing resx files (Bug#6216
     (http://bugs.mysql.com/6216))

   * Fixed System.OverflowException when using YEAR datatype (Bug#6036
     (http://bugs.mysql.com/6036))

   * Fixed MySqlDateTime sets IsZero property on all subseq.records
     after first zero found (Bug#6006 (http://bugs.mysql.com/6006))

   * Fixed serializing of floating point parameters (double, numeric,
     single, decimal) (Bug#5900 (http://bugs.mysql.com/5900))

   * Fixed missing Reference in DbType setter (Bug#5897
     (http://bugs.mysql.com/5897))

   * Fixed Parsing the ';' char (Bug#5876 (http://bugs.mysql.com/5876))

   * Fixed DBNull Values causing problems with retrieving/updating
     queries.  (Bug#5798 (http://bugs.mysql.com/5798))

   * IsNullable error (Bug#5796 (http://bugs.mysql.com/5796))

   * Fixed problem where MySqlParameterCollection.Add() would throw
     unclear exception when given a null value (Bug#5621
     (http://bugs.mysql.com/5621))

   * Fixed construtor initialize problems in MySqlCommand() (Bug#5613
     (http://bugs.mysql.com/5613))

   * Fixed Yet Another "object reference not set to an instance of an
     object" (Bug#5496 (http://bugs.mysql.com/5496))

   * Fixed Can't display Chinese correctly (Bug#5288
     (http://bugs.mysql.com/5288))

   * Fixed MySqlDataReader and 'show tables from ...' behavior
     (Bug#5256 (http://bugs.mysql.com/5256))

   * Fixed problem in PacketReader where it could try to allocate the
     wrong buffer size in EnsureCapacity

   * Fixed problem where using old syntax while using the interfaces
     caused problems

   * Fixed Bug#5458 (http://bugs.mysql.com/5458) Calling GetChars on a
     longtext column throws an exception

   * Added test case for resetting the command text on a prepared
     command

   * Fixed Bug#5388 (http://bugs.mysql.com/5388) DataReader reports all
     rows as NULL if one row is NULL

   * Fixed problem where connection lifetime on the connect string was
     not being respected

   * Fixed Bug#5602 (http://bugs.mysql.com/5602) Possible bug in
     MySqlParameter(string, object) constructor

   * Field buffers being reused to decrease memory allocations and
     increase speed

   * Fixed Bug#5392 (http://bugs.mysql.com/5392) MySqlCommand sees "?"
     as parameters in string literals

   * Added Aggregate function test (wasn't really a bug)

   * Using PacketWriter instead of Packet for writing to streams

   * Implemented SequentialAccess

   * Fixed problem with ConnectionInternal where a key might be added
     more than once

   * Fixed Russian character support as well

   * Fixed Bug#5474 (http://bugs.mysql.com/5474) cannot run a stored
     procedure populating mysqlcommand.parameters

   * Fixed problem where connector was not issuing a CMD_QUIT before
     closing the socket

   * Fixed problem where Min Pool Size was not being respected

   * Refactored compression code into CompressedStream to clean up
     NativeDriver

   * CP1252 is now used for Latin1 only when the server is 4.1.2 and
     later

   * Fixed Bug#5469 (http://bugs.mysql.com/5469) Setting DbType throws
     NullReferenceException

   * Virtualized driver subsystem so future releases could easily
     support client or embedded server support


File: manual.info,  Node: connector-net-news-1-0-0,  Next: connector-net-0-9-0,  Prev: connector-net-news-1-0-1,  Up: connector-net-news

C.5.44 Changes in MySQL Connector/NET 1.0.0 (01 September 2004)
---------------------------------------------------------------

Bugs fixed:

   * Thai encoding not correctly supported.  (Bug#3889
     (http://bugs.mysql.com/3889))

   * Bumped version number to 1.0.0 for beta 1 release.

   * Removed all of the XML comment warnings.

   * Added `COPYING.rtf' file for use in installer.

   * Updated many of the test cases.

   * Fixed problem with using compression.

   * Removed some last references to ByteFX.


File: manual.info,  Node: connector-net-0-9-0,  Next: connector-net-news-0-76,  Prev: connector-net-news-1-0-0,  Up: connector-net-news

C.5.45 Changes in MySQL Connector/NET Version 0.9.0 (30 August 2004)
--------------------------------------------------------------------

   * Added test fixture for prepared statements.

   * All type classes now implement a `SerializeBinary' method for
     sending their data to a `PacketWriter'.

   * Added `PacketWriter' class that will enable future low-memory
     large object handling.

   * Fixed many small bugs in running prepared statements and stored
     procedures.

   * Changed command so that an exception will not be thrown in
     executing a stored procedure with parameters in old syntax mode.

   * `SingleRow' behavior now working right even with limit.

   * `GetBytes' now only works on binary columns.

   * Logger now truncates long sql commands so blob columns do not blow
     out our log.

   * host and database now have a default value of "" unless otherwise
     set.

   * Connection Timeout seems to be ignored. (Bug#5214
     (http://bugs.mysql.com/5214))

   * Added test case for bug# 5051: GetSchema not working correctly.

   * Fixed problem where `GetSchema' would return false for `IsUnique'
     when the column is key.

   * `MySqlDataReader GetXXX' methods now using the field level
     `MySqlValue' object and not performing conversions.

   * `DataReader' returning `NULL' for time column. (Bug#5097
     (http://bugs.mysql.com/5097))

   * Added test case for *Note `LOAD DATA LOCAL INFILE': load-data.

   * Added replacetext custom nant task.

   * Added `CommandBuilderTest' fixture.

   * Added Last One Wins feature to `CommandBuilder'.

   * Fixed persist security info case problem.

   * Fixed `GetBool' so that 1, true, "true", and "yes" all count as
     true.

   * Make parameter mark configurable.

   * Added the "old syntax" connection string parameter to allow use of
     @ parameter marker.

   * `MySqlCommandBuilder'. (Bug#4658 (http://bugs.mysql.com/4658))

   * `ByteFX.MySqlClient' caches passwords if `Persist Security Info'
     is false. (Bug#4864 (http://bugs.mysql.com/4864))

   * Updated license banner in all source files to include FLOSS
     exception.

   * Added new .Types namespace and implementations for most current
     MySql types.

   * Added `MySqlField41' as a subclass of `MySqlField'.

   * Changed many classes to now use the new .Types types.

   * Changed type `enum int' to `Int32', `short' to `Int16', and
     `bigint' to `Int64'.

   * Added dummy types `UInt16', `UInt32', and `UInt64' to allow an
     unsigned parameter to be made.

   * Connections are now reset when they are pulled from the connection
     pool.

   * Refactored auth code in driver so it can be used for both auth and
     reset.

   * Added `UserReset' test in `PoolingTests.cs'.

   * Connections are now reset using `COM_CHANGE_USER' when pulled from
     the pool.

   * Implemented `SingleResultSet' behavior.

   * Implemented support of unicode.

   * Added char set mappings for utf-8 and ucs-2.

   * Time fields overflow using bytefx .net mysql driver (Bug#4520
     (http://bugs.mysql.com/4520))

   * Modified time test in data type test fixture to check for time
     spans where hours > 24.

   * Wrong string with backslash escaping in
     `ByteFx.Data.MySqlClient.MySqlParameter'.  (Bug#4505
     (http://bugs.mysql.com/4505))

   * Added code to Parameter test case TestQuoting to test for
     backslashes.

   * `MySqlCommandBuilder' fails with multi-word column names.
     (Bug#4486 (http://bugs.mysql.com/4486))

   * Fixed bug in `TokenizeSql' where underscore would terminate
     character capture in parameter name.

   * Added test case for spaces in column names.

   * `MySqlDataReader.GetBytes' do not work correctly. (Bug#4324
     (http://bugs.mysql.com/4324))

   * Added `GetBytes()' test case to `DataReader' test fixture.

   * Now reading all server variables in `InternalConnection.Configure'
     into `Hashtable'.

   * Now using `string[]' for index map in `CharSetMap'.

   * Added CRInSQL test case for carriage returns in SQL.

   * Setting maxPacketSize to default value in `Driver.ctor'.

   * Setting `MySqlDbType' on a parameter doesn't set generic type.
     (Bug#4442 (http://bugs.mysql.com/4442))

   * Removed obsolete data types `Long' and `LongLong'.

   * Overflow exception thrown when using "use pipe" on connection
     string. (Bug#4071 (http://bugs.mysql.com/4071))

   * Changed "use pipe" keyword to "pipe name" or just "pipe".

   * Allow reading multiple resultsets from a single query.

   * Added flags attribute to `ServerStatusFlags' enum.

   * Changed name of `ServerStatus' enum to `ServerStatusFlags'.

   * Inserted data row doesn't update properly.

   * Error processing show create table. (Bug#4074
     (http://bugs.mysql.com/4074))

   * Change `Packet.ReadLenInteger' to `ReadPackedLong' and added
     `packet.ReadPackedInteger' that always reads integers packed with
     2,3,4.

   * Added `syntax.cs' test fixture to test various SQL syntax bugs.

   * Improper handling of time values. Now time value of 00:00:00 is
     not treated as null. (Bug#4149 (http://bugs.mysql.com/4149))

   * Moved all test suite files into `TestSuite' folder.

   * Fixed bug where null column would move the result packet pointer
     backward.

   * Added new nant build script.

   * Clear tablename so it will be regen'ed properly during the next
     `GenerateSchema'. (Bug#3917 (http://bugs.mysql.com/3917))

   * `GetValues' was always returning zero and was also always trying
     to copy all fields rather than respecting the size of the array
     passed in. (Bug#3915 (http://bugs.mysql.com/3915))

   * Implemented shared memory access protocol.

   * Implemented prepared statements for MySQL 4.1.

   * Implemented stored procedures for MySQL 5.0.

   * Renamed `MySqlInternalConnection' to `InternalConnection'.

   * SQL is now parsed as chars, fixes problems with other languages.

   * Added logging and allow batch connection string options.

   * `RowUpdating' event not set when setting the `DataAdapter'
     property. (Bug#3888 (http://bugs.mysql.com/3888))

   * Fixed bug in char set mapping.

   * Implemented 4.1 authentication.

   * Improved open/auth code in driver.

   * Improved how connection bits are set during connection.

   * Database name is now passed to server during initial handshake.

   * Changed namespace for client to `MySql.Data.MySqlClient'.

   * Changed assembly name of client to `MySql.Data.dll'.

   * Changed license text in all source files to GPL.

   * Added the `MySqlClient.build' Nant file.

   * Removed the mono batch files.

   * Moved some of the unused files into notused folder so nant build
     file can use wildcards.

   * Implemented shared memory access.

   * Major revamp in code structure.

   * Prepared statements now working for MySql 4.1.1 and later.

   * Finished implementing auth for 4.0, 4.1.0, and 4.1.1.

   * Changed namespace from `MySQL.Data.MySQLClient' back to
     `MySql.Data.MySqlClient'.

   * Fixed bug in `CharSetMapping' where it was trying to use text
     names as ints.

   * Changed namespace to `MySQL.Data.MySQLClient'.

   * Integrated auth changes from UC2004.

   * Fixed bug where calling any of the GetXXX methods on a datareader
     before or after reading data would not throw the appropriate
     exception (thanks Luca Morelli).

   * Added `TimeSpan' code in parameter.cs to properly serialize a
     timespan object to mysql time format (thanks Gianluca Colombo).

   * Added `TimeStamp' to parameter serialization code. Prevented
     `DataAdatper' updates from working right (thanks Michael King).

   * Fixed a misspelling in `MySqlHelper.cs' (thanks Patrick
     Kristiansen).


File: manual.info,  Node: connector-net-news-0-76,  Next: connector-net-news-0-75,  Prev: connector-net-0-9-0,  Up: connector-net-news

C.5.46 Changes in MySQL Connector/NET Version 0.76
--------------------------------------------------

   * Driver now using charset number given in handshake to create
     encoding.

   * Changed command editor to point to `MySqlClient.Design'.

   * Fixed bug in `Version.isAtLeast'.

   * Changed `DBConnectionString' to support changes done to
     `MySqlConnectionString'.

   * Removed `SqlCommandEditor' and `DataAdapterPreviewDialog'.

   * Using new long return values in many places.

   * Integrated new `CompressedStream' class.

   * Changed `ConnectionString' and added attributes to allow it to be
     used in `MySqlClient.Design'.

   * Changed `packet.cs' to support newer lengths in `ReadLenInteger'.

   * Changed other classes to use new properties and fields of
     `MySqlConnectionString'.

   * `ConnectionInternal' is now using PING to see whether the server
     is alive.

   * Moved toolbox bitmaps into resource folder.

   * Changed `field.cs' to allow values to come directly from row
     buffer.

   * Changed to use the new driver.Send syntax.

   * Using a new packet queueing system.

   * Started work handling the "broken" compression packet handling.

   * Fixed bug in `StreamCreator' where failure to connect to a host
     would continue to loop infinitly (thanks Kevin Casella).

   * Improved connectstring handling.

   * Moved designers into Pro product.

   * Removed some old commented out code from `command.cs'.

   * Fixed a problem with compression.

   * Fixed connection object where an exception throw prior to the
     connection opening would not leave the connection in the
     connecting state (thanks Chris Cline).

   * Added GUID support.

   * Fixed sequence out of order bug (thanks Mark Reay).


File: manual.info,  Node: connector-net-news-0-75,  Next: connector-net-0-74,  Prev: connector-net-news-0-76,  Up: connector-net-news

C.5.47 Changes in MySQL Connector/NET Version 0.75
--------------------------------------------------

   * Enum values now supported as parameter values (thanks Philipp
     Sumi).

   * Year datatype now supported.

   * Fixed compression.

   * Fixed bug where a parameter with a `TimeSpan' as the value would
     not serialize properly.

   * Fixed bug where default constructor would not set default
     connection string values.

   * Added some XML comments to some members.

   * Work to fix/improve compression handling.

   * Improved `ConnectionString' handling so that it better matches the
     standard set by `SqlClient'.

   * A `MySqlException' is now thrown if a user name is not included in
     the connection string.

   * Localhost is now used as the default if not specified on the
     connection string.

   * An exception is now thrown if an attempt is made to set the
     connection string while the connection is open.

   * Small changes to `ConnectionString' docs.

   * Removed `MultiHostStream' and `MySqlStream'. Replaced it with
     `Common/StreamCreator'.

   * Added support for Use Pipe connection string value.

   * Added Platform class for easier access to platform utility
     functions.

   * Fixed small pooling bug where new connection was not getting
     created after `IsAlive' fails.

   * Added `Platform.cs' and `StreamCreator.cs'.

   * Fixed `Field.cs' to properly handle 4.1 style timestamps.

   * Changed `Common.Version' to `Common.DBVersion' to avoid name
     conflict.

   * Fixed `field.cs' so that text columns return the right field type.

   * Added `MySqlError' class to provide some reference for error codes
     (thanks Geert Veenstra).


File: manual.info,  Node: connector-net-0-74,  Next: connector-net-news-0-71,  Prev: connector-net-news-0-75,  Up: connector-net-news

C.5.48 Changes in MySQL Connector/NET Version 0.74
--------------------------------------------------

   * Added Unix socket support (thanks Mohammad DAMT).

   * Only calling `Thread.Sleep' when no data is available.

   * Improved escaping of quote characters in parameter data.

   * Removed misleading comments from `parameter.cs'.

   * Fixed pooling bug.

   * Fixed `ConnectionString' editor dialog (thanks marco p (pomarc)).

   * `UserId' now supported in connection strings (thanks Jeff Neeley).

   * Attempting to create a parameter that is not input throws an
     exception (thanks Ryan Gregg).

   * Added much documentation.

   * Checked in new `MultiHostStream' capability.  Big thanks to Dan
     Guisinger for this. he originally submitted the code and idea of
     supporting multiple machines on the connect string.

   * Added a lot of documentation.

   * Fixed speed issue with 0.73.

   * Changed to Thread.Sleep(0) in MySqlDataStream to help optimize the
     case where it doesn't need to wait (thanks Todd German).

   * Prepopulating the idlepools to `MinPoolSize'.

   * Fixed `MySqlPool' deadlock condition as well as stupid bug where
     CreateNewPooledConnection was not ever adding new connections to
     the pool. Also fixed `MySqlStream.ReadBytes' and `ReadByte' to not
     use `TicksPerSecond' which does not appear to always be right.
     (thanks Matthew J. Peddlesden)

   * Fix for precision and scale (thanks Matthew J. Peddlesden).

   * Added `Thread.Sleep(1)' to stream reading methods to be more cpu
     friendly (thanks Sean McGinnis).

   * Fixed problem where `ExecuteReader' would sometime return null
     (thanks Lloyd Dupont).

   * Fixed major bug with null field handling (thanks Naucki).

   * Enclosed queries for `max_allowed_packet' and `characterset'
     inside try catch (and set defaults).

   * Fixed problem where socket was not getting closed properly (thanks
     Steve!).

   * Fixed problem where `ExecuteNonQuery' was not always returning the
     right value.

   * Fixed `InternalConnection' to not use
     `@@session.max_allowed_packet' but use `@@max_allowed_packet'.
     (Thanks Miguel)

   * Added many new XML doc lines.

   * Fixed sql parsing to not send empty queries (thanks Rory).

   * Fixed problem where the reader was not unpeeking the packet on
     close.

   * Fixed problem where user variables were not being handled (thanks
     Sami Vaaraniemi).

   * Fixed loop checking in the MySqlPool (thanks Steve M. Brown)

   * Fixed `ParameterCollection.Add' method to match `SqlClient'
     (thanks Joshua Mouch).

   * Fixed `ConnectionString' parsing to handle no and yes for boolean
     and not lowercase values (thanks Naucki).

   * Added `InternalConnection' class, changes to pooling.

   * Implemented Persist Security Info.

   * Added `security.cs' and `version.cs' to project

   * Fixed `DateTime' handling in `Parameter.cs' (thanks Burkhard
     Perkens-Golomb).

   * Fixed parameter serialization where some types would throw a cast
     exception.

   * Fixed `DataReader' to convert all returned values to prevent
     casting errors (thanks Keith Murray).

   * Added code to `Command.ExecuteReader' to return null if the
     initial SQL statement throws an exception (thanks Burkhard
     Perkens-Golomb).

   * Fixed `ExecuteScalar' bug introduced with restructure.

   * Restructure to allow for `LOCAL DATA INFILE' and better sequencing
     of packets.

   * Fixed several bugs related to restructure.

   * Early work done to support more secure passwords in Mysql 4.1.
     Old passwords in 4.1 not supported yet.

   * Parameters appearing after system parameters are now handled
     correctly (Adam M. (adammil)).

   * Strings can now be assigned directly to blob fields (Adam M.).

   * Fixed float parameters (thanks Pent).

   * Improved Parameter constructor and `ParameterCollection.Add'
     methods to better match SqlClient (thanks Joshua Mouch).

   * Corrected `Connection.CreateCommand' to return a `MySqlCommand'
     type.

   * Fixed connection string designer dialog box problem (thanks
     Abraham Guyt).

   * Fixed problem with sending commands not always reading the
     response packet (thanks Joshua Mouch).

   * Fixed parameter serialization where some blobs types were not
     being handled (thanks Sean McGinnis).

   * Removed spurious `MessageBox.show' from `DataReader' code (thanks
     Joshua Mouch).

   * Fixed a nasty bug in the split sql code (thanks everyone!).


File: manual.info,  Node: connector-net-news-0-71,  Next: connector-net-news-0-70,  Prev: connector-net-0-74,  Up: connector-net-news

C.5.49 Changes in MySQL Connector/NET Version 0.71
--------------------------------------------------

   * Fixed bug in `MySqlStream' where too much data could attempt to be
     read (thanks Peter Belbin)

   * Implemented `HasRows' (thanks Nash Pherson).

   * Fixed bug where tables with more than 252 columns cause an
     exception (thanks Joshua Kessler).

   * Fixed bug where SQL statements ending in ; would cause a problem
     (thanks Shane Krueger).

   * Fixed bug in driver where error messages were getting truncated by
     1 character (thanks Shane Krueger).

   * Made `MySqlException' serializable (thanks Mathias Hasselmann).


File: manual.info,  Node: connector-net-news-0-70,  Next: connector-net-news-0-68,  Prev: connector-net-news-0-71,  Up: connector-net-news

C.5.50 Changes in MySQL Connector/NET Version 0.70
--------------------------------------------------

   * Updated some of the character code pages to be more accurate.

   * Fixed problem where readers could be opened on connections that
     had readers open.

   * Moved test to separate assembly `MySqlClientTests'.

   * Fixed stupid problem in driver with sequence out of order (Thanks
     Peter Belbin).

   * Added some pipe tests.

   * Increased default max pool size to 50.

   * Compiles with Mono 0-24.

   * Fixed connection and data reader dispose problems.

   * Added `String' datatype handling to parameter serialization.

   * Fixed sequence problem in driver that occurred after thrown
     exception (thanks Burkhard Perkens-Golomb).

   * Added support for `CommandBehavior.SingleRow' to `DataReader'.

   * Fixed command sql processing so quotes are better handled (thanks
     Theo Spears).

   * Fixed parsing of double, single, and decimal values to account for
     non-English separators. You still have to use the right syntax if
     you using hard coded sql, but if you use parameters the code will
     convert floating point types to use '.'  appropriately internal
     both into the server and out.

   * Added `MySqlStream' class to simplify timeouts and driver coding.

   * Fixed `DataReader' so that it is closed properly when the
     associated connection is closed. [thanks smishra]

   * Made client more SqlClient compliant so that DataReaders have to
     be closed before the connection can be used to run another command.

   * Improved `DBNull.Value' handling in the fields.

   * Added several unit tests.

   * Fixed `MySqlException' base class.

   * Improved driver coding

   * Fixed bug where NextResult was returning false on the last
     resultset.

   * Added more tests for MySQL.

   * Improved casting problems by equating unsigned 32bit values to
     Int64 and unsigned 16bit values to Int32, and so forth.

   * Added new constructor for `MySqlParameter' for (name, type, size,
     srccol)

   * Fixed bug in `MySqlDataReader' where it didn't check for null
     fieldlist before returning field count.

   * Started adding `MySqlClient' unit tests (added `MySqlClient/Tests'
     folder and some test cases).

   * Fixed some things in Connection String handling.

   * Moved `INIT_DB' to `MySqlPool'. I may move it again, this is in
     preparation of the conference.

   * Fixed bug inside `CommandBuilder' that prevented inserts from
     happening properly.

   * Reworked some of the internals so that all three execute methods
     of Command worked properly.

   * Fixed many small bugs found during benchmarking.

   * The first cut of `CoonectionPooling' is working. "min pool size"
     and "max pool size" are respected.

   * Work to enable multiple resultsets to be returned.

   * Character sets are handled much more intelligently now. The driver
     queries MySQL at startup for the default character set.  That
     character set is then used for conversions if that code page can
     be loaded. If not, then the default code page for the current OS
     is used.

   * Added code to save the inferred type in the name,value constructor
     of `Parameter'.

   * Also, inferred type if value of null parameter is changed using
     `Value' property.

   * Converted all files to use proper Camel case. MySQL is now MySql
     in all files. PgSQL is now PgSql.

   * Added attribute to PgSql code to prevent designer from trying to
     show.

   * Added `MySQLDbType' property to Parameter object and added proper
     conversion code to convert from `DbType' to `MySQLDbType').

   * Removed unused `ObjectToString' method from `MySQLParameter.cs'.

   * Fixed `Add(..)' method in `ParameterCollection' so that it doesn't
     use `Add(name, value)' instead.

   * Fixed `IndexOf' and `Contains' in `ParameterCollection' to be
     aware that parameter names are now stored without @.

   * Fixed `Command.ConvertSQLToBytes' so it only allows characters
     that can be in MySQL variable names.

   * Fixed `DataReader' and `Field' so that blob fields read their data
     from `Field.cs' and `GetBytes' works right.

   * Added simple query builder editor to `CommandText' property of
     `MySQLCommand'.

   * Fixed `CommandBuilder' and `Parameter' serialization to account for
     Parameters not storing @ in their names.

   * Removed `MySQLFieldType' enum from Field.cs.  Now using
     `MySQLDbType' enum.

   * Added `Designer' attribute to several classes to prevent designer
     view when using VS.Net.

   * Fixed Initial catalog typo in `ConnectionString' designer.

   * Removed 3 parameter constructor for `MySQLParameter' that
     conflicted with (name, type, value).

   * Changed `MySQLParameter' so `paramName' is now stored without
     leading @ (this fixed null inserts when using designer).

   * Changed `TypeConverter' for `MySQLParameter' to use the
     constructor with all properties.


File: manual.info,  Node: connector-net-news-0-68,  Next: connector-net-news-0-65,  Prev: connector-net-news-0-70,  Up: connector-net-news

C.5.51 Changes in MySQL Connector/NET Version 0.68
--------------------------------------------------

   * Fixed sequence issue in driver.

   * Added `DbParametersEditor' to make parameter editing more like
     `SqlClient'.

   * Fixed `Command' class so that parameters can be edited using the
     designer

   * Update connection string designer to support `Use Compression'
     flag.

   * Fixed string encoding so that European characters will work
     correctly.

   * Creating base classes to aid in building new data providers.

   * Added support for UID key in connection string.

   * Field, parameter, command now using DBNull.Value instead of null.

   * `CommandBuilder' using `DBNull.Value'.

   * `CommandBuilder' now builds insert command correctly when an
     auto_insert field is not present.

   * Field now uses typeof keyword to return `System.Types'
     (performance).


File: manual.info,  Node: connector-net-news-0-65,  Next: connector-net-news-0-60,  Prev: connector-net-news-0-68,  Up: connector-net-news

C.5.52 Changes in MySQL Connector/NET Version 0.65
--------------------------------------------------

   * `MySQLCommandBuilder' now implemented.

   * Transaction support now implemented (not all table types support
     this).

   * `GetSchemaTable' fixed to not use xsd (for Mono).

   * Driver is now Mono-compatible.

   * TIME data type now supported.

   * More work to improve Timestamp data type handling.

   * Changed signatures of all classes to match corresponding
     `SqlClient' classes.


File: manual.info,  Node: connector-net-news-0-60,  Next: connector-net-news-0-50,  Prev: connector-net-news-0-65,  Up: connector-net-news

C.5.53 Changes in MySQL Connector/NET Version 0.60
--------------------------------------------------

   * Protocol compression using SharpZipLib (www.icsharpcode.net).

   * Named pipes on Windows now working properly.

   * Work done to improve `Timestamp' data type handling.

   * Implemented `IEnumerable' on `DataReader' so `DataGrid' would work.


File: manual.info,  Node: connector-net-news-0-50,  Prev: connector-net-news-0-60,  Up: connector-net-news

C.5.54 Changes in MySQL Connector/NET Version 0.50
--------------------------------------------------

   * Speed increased dramatically by removing bugging network sync code.

   * Driver no longer buffers rows of data (more ADO.Net compliant).

   * Conversion bugs related to *Note `TIMESTAMP': datetime. and *Note
     `DATETIME': datetime. fields fixed.


File: manual.info,  Node: vstudio-plugin-news,  Next: cj-news,  Prev: connector-net-news,  Up: news

C.6 MySQL Visual Studio Plugin Change History
=============================================

* Menu:

* vstudio-plugin-news-1-0-3::    Changes in MySQL Visual Studio Plugin 1.0.3 (Not yet released)
* vstudio-plugin-news-1-0-2::    Changes in MySQL Visual Studio Plugin 1.0.2 (Not yet released)
* vstudio-plugin-news-1-0-1::    Changes in MySQL Visual Studio Plugin 1.0.1 (4 October 2006)
* vstudio-plugin-news-1-0-0::    Changes in MySQL Visual Studio Plugin 1.0.0 (4 October 2006)

*Note*:

As of Connector/NET 5.1.2 (14 June 2007), the Visual Studion Plugin is
part of the main Connector/NET package. For the change history for the
Visual Studio Plugin, see *Note connector-net-news::.


File: manual.info,  Node: vstudio-plugin-news-1-0-3,  Next: vstudio-plugin-news-1-0-2,  Prev: vstudio-plugin-news,  Up: vstudio-plugin-news

C.6.1 Changes in MySQL Visual Studio Plugin 1.0.3 (Not yet released)
--------------------------------------------------------------------

Bugs fixed:

   * Running queries based on a stored procedure would cause the data
     set designer to terminate. (Bugs #26364)

   * DataSet wizard would show all tables instead of only the tables
     available within the selected database. (Bugs #26348)


File: manual.info,  Node: vstudio-plugin-news-1-0-2,  Next: vstudio-plugin-news-1-0-1,  Prev: vstudio-plugin-news-1-0-3,  Up: vstudio-plugin-news

C.6.2 Changes in MySQL Visual Studio Plugin 1.0.2 (Not yet released)
--------------------------------------------------------------------

Bugs fixed:

   * The Add Connection dialog of the Server Explorer would freeze when
     accessing databases with capitalized characters in their name.
     (Bug#24875 (http://bugs.mysql.com/24875))

   * Creating a connection through the Server Explorer when using the
     Visual Studio Plugin would fail. The installer for the Visual
     Studio Plugin has been updated to ensure that Connector/NET 5.0.2
     must be installed.  (Bug#23071 (http://bugs.mysql.com/23071))


File: manual.info,  Node: vstudio-plugin-news-1-0-1,  Next: vstudio-plugin-news-1-0-0,  Prev: vstudio-plugin-news-1-0-2,  Up: vstudio-plugin-news

C.6.3 Changes in MySQL Visual Studio Plugin 1.0.1 (4 October 2006)
------------------------------------------------------------------

This is a bug fix release to resolve an incompatibility issue with
Connector/NET 5.0.1.

It is critical that this release only be used with Connector/NET 5.0.1.
After installing Connector/NET 5.0.1, you will need to make a small
change in your machine.config file. This file should be located at
`%win%\Microsoft.Net\Framework\v2.0.50727\CONFIG\machine.config'
(`%win%' should be the location of your Windows folder). Near the
bottom of the file you will see a line like this:

     <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient"
     description=".Net Framework Data Provider for MySQL"
     type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data"/>

It needs to be changed to be like this:

     <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient"
     description=".Net Framework Data Provider for MySQL"
     type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data,
     Version=5.0.1.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"/>


File: manual.info,  Node: vstudio-plugin-news-1-0-0,  Prev: vstudio-plugin-news-1-0-1,  Up: vstudio-plugin-news

C.6.4 Changes in MySQL Visual Studio Plugin 1.0.0 (4 October 2006)
------------------------------------------------------------------

Bugs fixed:

   * Ability to work with MySQL objects (tables, views, stored
     procedures, etc) from within Server Explorer.

   * DDEX (Data Designer Extensibility) compatibility.


File: manual.info,  Node: cj-news,  Next: news-connector-mxj,  Prev: vstudio-plugin-news,  Up: news

C.7 MySQL Connector/J Change History
====================================

* Menu:

* cj-news-5-1::                  Changes in MySQL Connector/J 5.1.x
* cj-news-5-0::                  Changes in MySQL Connector/J 5.0.x
* cg-news-3-1::                  Changes in MySQL Connector/J 3.1.x
* cg-news-3-0::                  Changes in MySQL Connector/J 3.0.x
* cj-news-2-0::                  Changes in MySQL Connector/J 2.0.x
* cj-news-1-2b::                 Changes in MySQL Connector/J 1.2b (04 July 1999)
* cg-news-1-0::                  Changes in MySQL Connector/J 1.2.x and lower


File: manual.info,  Node: cj-news-5-1,  Next: cj-news-5-0,  Prev: cj-news,  Up: cj-news

C.7.1 Changes in MySQL Connector/J 5.1.x
----------------------------------------

* Menu:

* cj-news-5-1-8::                Changes in MySQL Connector/J 5.1.8 (Not yet released)
* cj-news-5-1-7::                Changes in MySQL Connector/J 5.1.7 (21 October 2008)
* cj-news-5-1-6::                Changes in MySQL Connector/J 5.1.6 (07 March 2008)
* cj-news-5-1-5::                Changes in MySQL Connector/J 5.1.5 (09 October 2007)
* cj-news-5-1-4::                Changes in MySQL Connector/J 5.1.4 (Not Released)
* cj-news-5-1-3::                Changes in MySQL Connector/J 5.1.3 (10 September 2007)
* cj-news-5-1-2::                Changes in MySQL Connector/J 5.1.2 (29 June 2007)
* cj-news-5-1-1::                Changes in MySQL Connector/J 5.1.1 (22 June 2007)
* cj-news-5-1-0::                Changes in MySQL Connector/J 5.1.0 (11 April 2007)


File: manual.info,  Node: cj-news-5-1-8,  Next: cj-news-5-1-7,  Prev: cj-news-5-1,  Up: cj-news-5-1

C.7.1.1 Changes in MySQL Connector/J 5.1.8 (Not yet released)
.............................................................

Bugs fixed:

   * `Statement.getGeneratedKeys()' retained result set instances until
     the statement was closed. This caused memory leaks for long-lived
     statements, or statements used in tight loops.  (Bug#44056
     (http://bugs.mysql.com/44056))

   * `LoadBalancingConnectionProxy.doPing()' did not have blacklist
     awareness.

     `LoadBalancingConnectionProxy' implemented `doPing()' to ping all
     underlying connections, but it threw any exceptions it encountered
     during this process.

     With the global blacklist enabled, it catches these exceptions,
     adds the host to the global blacklist, and only throws an
     exception if all hosts are down.  (Bug#43421
     (http://bugs.mysql.com/43421))

   * When the MySQL Server was upgraded from 4.0 to 5.0, the
     Connector/J application then failed to connect to the server.
     This was because authentication failed when the application ran
     from EBCDIC platforms such as z/OS.  (Bug#43071
     (http://bugs.mysql.com/43071))

   * When connecting with `traceProtocol=true', no trace data was
     generated for the server greeting or login request.  (Bug#43070
     (http://bugs.mysql.com/43070))

   * A `ConcurrentModificationException' was generated in
     `LoadBalancingConnectionProxy':

          java.util.ConcurrentModificationException
           at java.util.HashMap$HashIterator.nextEntry(Unknown Source)
           at java.util.HashMap$KeyIterator.next(Unknown Source)
           at
          com.mysql.jdbc.LoadBalancingConnectionProxy.getGlobalBlacklist(LoadBalancingConnectionProxy.java:520)
           at com.mysql.jdbc.RandomBalanceStrategy.pickConnection(RandomBalanceStrategy.java:55)
           at
          com.mysql.jdbc.LoadBalancingConnectionProxy.pickNewConnection(LoadBalancingConnectionProxy.java:414)
           at
          com.mysql.jdbc.LoadBalancingConnectionProxy.invoke(LoadBalancingConnectionProxy.java:390)

     (Bug#42055 (http://bugs.mysql.com/42055))

   * MySQL Connector/J 5.1.7 was slower than previous versions when the
     `rewriteBatchedStatements' option was set to `true'.

     *Note*:

     The performance regression in
     `indexOfIgnoreCaseRespectMarker()'has been fixed. It has also been
     made possible for the driver to rewrite `INSERT' statements with
     `ON DUPLICATE KEY UPDATE' clauses in them, as long as the `UPDATE'
     clause contains no reference to `LAST_INSERT_ID()', as that would
     cause the driver to return bogus values for `getGeneratedKeys()'
     invocations. This has resulted in improved performance over
     version 5.1.7.

     (Bug#41532 (http://bugs.mysql.com/41532))

   * `PreparedStatement.addBatch()' did not check for all parameters
     being set, which led to inconsistent behavior in `executeBatch()',
     especially when rewriting batched statements into multi-value
     `INSERT's.  (Bug#41161 (http://bugs.mysql.com/41161))


File: manual.info,  Node: cj-news-5-1-7,  Next: cj-news-5-1-6,  Prev: cj-news-5-1-8,  Up: cj-news-5-1

C.7.1.2 Changes in MySQL Connector/J 5.1.7 (21 October 2008)
............................................................

Functionality added or changed:

   * When statements include `ON DUPLICATE UPDATE', and
     `rewriteBatchedStatements' is set to true, batched statements are
     not rewritten into the form `INSERT INTO table VALUES (), (), ()',
     instead the statements are executed sequentially.

Bugs fixed:

   * `Statement.getGeneratedKeys()' returned two keys when using `ON
     DUPLICATE KEY UPDATE' and the row was updated, not inserted.
     (Bug#42309 (http://bugs.mysql.com/42309))

   * When using the replication driver with `autoReconnect=true',
     Connector/J checks in `PreparedStatement.execute' (also called by
     `CallableStatement.execute') to determine if the first character
     of the statement is an `S', in an attempt to block all statements
     that are not read-only-safe, for example non-*Note `SELECT':
     select.  statements. However, this also blocked *Note `CALL':
     call.s to stored procedures, even if the stored procedures were
     defined as `SQL READ DATA' or `NO SQL'.  (Bug#40031
     (http://bugs.mysql.com/40031))

   * With large result sets `ResultSet.findColumn' became a performance
     bottleneck.  (Bug#39962 (http://bugs.mysql.com/39962))

   * Connector/J ignored the value of the MySQL Server variable
     `auto_increment_increment'.  (Bug#39956
     (http://bugs.mysql.com/39956))

   * Connector/J failed to parse *Note `TIMESTAMP': datetime. strings
     for nanos correctly.  (Bug#39911 (http://bugs.mysql.com/39911))

   * When the `LoadBalancingConnectionProxy' handles a `SQLException'
     with SQL state starting with `08', it calls
     `invalidateCurrentConnection', which in turn removes that
     `Connection' from `liveConnections' and the
     `connectionsToHostsMap', but it did not add the host to the new
     global blacklist, if the global blacklist was enabled.

     There was also the possibility of a `NullPointerException' when
     trying to update stats, where
     `connectionsToHostsMap.get(this.currentConn)' was called:

          int hostIndex = ((Integer) this.hostsToListIndexMap.get(this.connectionsToHostsMap.get(this.currentConn))).intValue();

     This could happen if a client tried to issue a rollback after
     catching a `SQLException' caused by a connection failure.
     (Bug#39784 (http://bugs.mysql.com/39784))

   * When configuring the Java Replication Driver the last slave
     specified was never used.  (Bug#39611
     (http://bugs.mysql.com/39611))

   * When an `INSERT ON DUPLICATE KEY UPDATE' was performed, and the
     key already existed, the `affected-rows' value was returned as 1
     instead of 0.  (Bug#39352 (http://bugs.mysql.com/39352))

   * When using the random load balancing strategy and starting with
     two servers that were both unavailable, an
     `IndexOutOfBoundsException' was generated when removing a server
     from the `whiteList'.  (Bug#38782 (http://bugs.mysql.com/38782))

   * Connector/J threw the following exception when using a read-only
     connection:

                  java.sql.SQLException: Connection is read-only. Queries leading to data
                  modification are not allowed.

     (Bug#38747 (http://bugs.mysql.com/38747))

   * Connector/J was unable to connect when using a non-latin1 password.
     (Bug#37570 (http://bugs.mysql.com/37570))

   * Incorrect result is returned from `isAfterLast()' in streaming
     `ResultSet' when using `setFetchSize(Integer.MIN_VALUE)'.
     (Bug#35170 (http://bugs.mysql.com/35170))

   * When `getGeneratedKeys()' was called on a statement that had not
     been created with `RETURN_GENERATED_KEYS', no exception was
     thrown, and batched executions then returned erroneous values.
     (Bug#34185 (http://bugs.mysql.com/34185))

   * The `loadBalance' `bestResponseTime' blacklists did not have a
     global state.  (Bug#33861 (http://bugs.mysql.com/33861))


File: manual.info,  Node: cj-news-5-1-6,  Next: cj-news-5-1-5,  Prev: cj-news-5-1-7,  Up: cj-news-5-1

C.7.1.3 Changes in MySQL Connector/J 5.1.6 (07 March 2008)
..........................................................

Functionality added or changed:

   * Multiple result sets were not supported when using streaming mode
     to return data. Both normal statements and the resul sets from
     stored procedures now return multiple results sets, with the
     exception of result sets using registered `OUTPUT' paramaters.
     (Bug#33678 (http://bugs.mysql.com/33678))

   * XAConnections and datasources have been updated to the JDBC-4.0
     standard.

   * The profiler event handling has been made extensible via the
     `profilerEventHandler' connection property.

   * Add the `verifyServerCertificate' propery. If set to "false" the
     driver will not verify the server's certificate when `useSSL' is
     set to "true"

     When using this feature, the keystore parameters should be
     specified by the `clientCertificateKeyStore*' properties, rather
     than system properties, as the JSSE doesn't it straightforward to
     have a non-verifying trust store and the "default" key store.

Bugs fixed:

   * DatabaseMetaData.getColumns() returns incorrect `COLUMN_SIZE'
     value for `SET' column.  (Bug#36830 (http://bugs.mysql.com/36830))

   * When trying to read Time values like `00:00:00' with
     ResultSet.getTime(int) an exception is thrown.  (Bug#36051
     (http://bugs.mysql.com/36051))

   * JDBC connection URL parameters is ignored when using
     `MysqlConnectionPoolDataSource'.  (Bug#35810
     (http://bugs.mysql.com/35810))

   * When `useServerPrepStmts=true' and slow query logging is enabled,
     the connector throws a NullPointerException when it encounters a
     slow query.  (Bug#35666 (http://bugs.mysql.com/35666))

   * When using the keyword `loadbalance' in the connection string and
     trying to perform load balancing between two databases, the driver
     appears to hang.  (Bug#35660 (http://bugs.mysql.com/35660))

   * JDBC data type getter method was changed to accept only column
     name, whereas previously it accepted column label.  (Bug#35610
     (http://bugs.mysql.com/35610))

   * Prepared statements from pooled connections caused a
     NullPointerException when closed() under JDBC-4.0.  (Bug#35489
     (http://bugs.mysql.com/35489))

   * In calling a stored function returning a `bigint', an exception is
     encountered beginning:

          java.sql.SQLException: java.lang.NumberFormatException: For input string:

     followed by the text of the stored function starting after the
     argument list.  (Bug#35199 (http://bugs.mysql.com/35199))

   * The JDBC driver uses a different method for evaluating column
     names in resultsetmetadata.getColumnName() and when looking for a
     column in resultset.getObject(columnName). This causes Hibernate
     to fail in queries where the two methods yield different results,
     for example in queries that use alias names:

          SELECT column AS aliasName from table

     (Bug#35150 (http://bugs.mysql.com/35150))

   * `MysqlConnectionPoolDataSource' does not support
     `ReplicationConnection'. Notice that we implemented
     `com.mysql.jdbc.Connection' for `ReplicationConnection', however,
     only accessors from ConnectionProperties are implemented (not the
     mutators), and they return values from the currently active
     connection. All other methods from `com.mysql.jdbc.Connection' are
     implemented, and operate on the currently active connection, with
     the exception of `resetServerState()' and `changeUser()'.
     (Bug#34937 (http://bugs.mysql.com/34937))

   * `ResultSet.getTimestamp()' returns incorrect values for month/day
     of *Note `TIMESTAMP': datetime.s when using server-side prepared
     statements (not enabled by default).  (Bug#34913
     (http://bugs.mysql.com/34913))

   * RowDataStatic does't always set the metadata in ResultSetRow,
     which can lead to failures when unpacking *Note `DATE': datetime,
     *Note `TIME': time, *Note `DATETIME': datetime. and *Note
     `TIMESTAMP': datetime. types when using absolute, relative, and
     previous result set navigation methods.  (Bug#34762
     (http://bugs.mysql.com/34762))

   * When calling `isValid()' on an active connection, if the timeout
     is non-zero then the `Connection' is invalidated even if the
     `Connection' is valid.  (Bug#34703 (http://bugs.mysql.com/34703))

   * It was not possible to truncate a *Note `BLOB': blob. using
     `Blog.truncate()' when using 0 as an argument.  (Bug#34677
     (http://bugs.mysql.com/34677))

   * When using a cursor fetch for a statement, the internal prepared
     statement could cause a memory leak until the connection was
     closed. The internal prepared statement is now deleted when the
     corresponding result set is closed.  (Bug#34518
     (http://bugs.mysql.com/34518))

   * When retrieving the column type name of a geometry field, the
     driver would return `UNKNOWN' instead of `GEOMETRY'.  (Bug#34194
     (http://bugs.mysql.com/34194))

   * Statements with batched values do not return correct values for
     `getGeneratedKeys()' when `rewriteBatchedStatements' is set to
     `true', and the statement has an `ON DUPLICATE KEY UPDATE' clause.
     (Bug#34093 (http://bugs.mysql.com/34093))

   * The internal class ResultSetInternalMethods referenced the
     non-public class com.mysql.jdbc.CachedResultSetMetaData.
     (Bug#33823 (http://bugs.mysql.com/33823))

   * A `NullPointerException' could be raised when using client-side
     prepared statements and enabled the prepared statement cache using
     the `cachePrepStmts'.  (Bug#33734 (http://bugs.mysql.com/33734))

   * Using server side cursors and cursor fetch, the table metadata
     information would return the data type name instead of the column
     name.  (Bug#33594 (http://bugs.mysql.com/33594))

   * ResultSet.getTimestamp() would throw a `NullPointerException'
     instead of a `SQLException' when called on an empty `ResultSet'.
     (Bug#33162 (http://bugs.mysql.com/33162))

   * Load balancing connection using best response time would
     incorrectly "stick" to hosts that were down when the connection
     was first created.

     We solve this problem with a black list that is used during the
     picking of new hosts. If the black list ends up including all
     configured hosts, the driver will retry for a configurable number
     of times (the `retriesAllDown' configuration property, with a
     default of 120 times), sleeping 250ms between attempts to pick a
     new connection.

     We've also went ahead and made the balancing strategy extensible.
     To create a new strategy, implement the interface
     com.mysql.jdbc.BalanceStrategy (which also includes our standard
     "extension" interface), and tell the driver to use it by passing
     in the class name via the `loadBalanceStrategy' configuration
     property.  (Bug#32877 (http://bugs.mysql.com/32877))

   * During a Daylight Savings Time (DST) switchover, there was no way
     to store two timestamp/datetime values , as the hours end up being
     the same when sent as the literal that MySQL requires.

     Note that to get this scenario to work with MySQL (since it
     doesn't support per-value timezones), you need to configure your
     server (or session) to be in UTC, and tell the driver not to use
     the legacy date/time code by setting `useLegacyDatetimeCode' to
     "false". This will cause the driver to always convert to/from the
     server and client timezone consistently.

     This bug fix also fixes Bug#15604 (http://bugs.mysql.com/15604),
     by adding entirely new date/time handling code that can be
     switched on by `useLegacyDatetimeCode' being set to "false" as a
     JDBC configuration property. For Connector/J 5.1.x, the default is
     "true", in trunk and beyond it will be "false" (i.e. the old
     date/time handling code will be deprecated) (Bug#32577
     (http://bugs.mysql.com/32577), Bug#15604
     (http://bugs.mysql.com/15604))

   * When unpacking rows directly, we don't hand off error message
     packets to the internal method which decodes them correctly, so no
     exception is raised, and the driver than hangs trying to read rows
     that aren't there. This tends to happen when calling stored
     procedures, as normal SELECTs won't have an error in this spot in
     the protocol unless an I/O error occurs.  (Bug#32246
     (http://bugs.mysql.com/32246))

   * When using a connection from ConnectionPoolDataSource, some
     `Connection.prepareStatement()' methods would return null instead
     of the prepared statement.  (Bug#32101
     (http://bugs.mysql.com/32101))

   * Using `CallableStatement.setNull()' on a stored function would
     throw an `ArrayIndexOutOfBounds' exception when setting the last
     parameter to null.  (Bug#31823 (http://bugs.mysql.com/31823))

   * MysqlValidConnectionChecker doesn't properly handle connections
     created using ReplicationConnection.  (Bug#31790
     (http://bugs.mysql.com/31790))

   * Retrieving the server version information for an active connection
     could return invalid information if the default character encoding
     on the host was not ASCII compatible.  (Bug#31192
     (http://bugs.mysql.com/31192))

   * Further fixes have been made to this bug in the event that a node
     is non-responsive. Connector/J will now try a different random
     node instead of waiting for the node to recover before continuing.
     (Bug#31053 (http://bugs.mysql.com/31053))

   * `ResultSet' returned by `Statement.getGeneratedKeys()' is not
     closed automatically when statement that created it is closed.
     (Bug#30508 (http://bugs.mysql.com/30508))

   * `DatabaseMetadata.getColumns()' doesn't return the correct column
     names if the connection character isn't UTF-8. A bug in MySQL
     server compounded the issue, but was fixed within the MySQL 5.0
     release cycle. The fix includes changes to all the sections of the
     code that access the server metadata.  (Bug#20491
     (http://bugs.mysql.com/20491))

   * Fixed ResultSetMetadata.getColumnName() for result sets returned
     from Statement.getGeneratedKeys() - it was returning null instead
     of "GENERATED_KEY" as in 5.0.x.


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C.7.1.4 Changes in MySQL Connector/J 5.1.5 (09 October 2007)
............................................................

The following     features are new, compared to the 5.0 series of
Connector/J

   * Support for JDBC-4.0 *Note `NCHAR': char, *Note `NVARCHAR': char.
     and `NCLOB' types.

   * JDBC-4.0 support for setting per-connection client information
     (which can be viewed in the comments section of a query via *Note
     `SHOW PROCESSLIST': show-processlist. on a MySQL server, or can be
     extended to support custom persistence of the information via a
     public interface).

   * Support for JDBC-4.0 XML processing via JAXP interfaces to DOM,
     SAX and StAX.

   * JDBC-4.0 standardized unwrapping to interfaces that include vendor
     extensions.

Functionality added or changed:

   * Added `autoSlowLog' configuration property, overrides
     `slowQueryThreshold*' properties, driver determines slow queries
     by those that are slower than 5 * stddev of the mean query time
     (outside the 96% percentile).

Bugs fixed:

   * When a connection is in read-only mode, queries that are wrapped
     in parentheses were incorrectly identified DML statements.
     (Bug#28256 (http://bugs.mysql.com/28256))


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C.7.1.5 Changes in MySQL Connector/J 5.1.4 (Not Released)
.........................................................

Only released internally.


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C.7.1.6 Changes in MySQL Connector/J 5.1.3 (10 September 2007)
..............................................................

The following     features are new, compared to the 5.0 series of
Connector/J

   * Support for JDBC-4.0 *Note `NCHAR': char, *Note `NVARCHAR': char.
     and `NCLOB' types.

   * JDBC-4.0 support for setting per-connection client information
     (which can be viewed in the comments section of a query via *Note
     `SHOW PROCESSLIST': show-processlist. on a MySQL server, or can be
     extended to support custom persistence of the information via a
     public interface).

   * Support for JDBC-4.0 XML processing via JAXP interfaces to DOM,
     SAX and StAX.

   * JDBC-4.0 standardized unwrapping to interfaces that include vendor
     extensions.

Functionality added or changed:

   * Connector/J now connects using an initial character set of `utf-8'
     solely for the purpose of authentication to allow user names or
     database names in any character set to be used in the JDBC
     connection URL.  (Bug#29853 (http://bugs.mysql.com/29853))

   * Added two configuration parameters:

        * `blobsAreStrings' -- Should the driver always treat BLOBs as
          Strings. Added specifically to work around dubious metadata
          returned by the server for `GROUP BY' clauses. Defaults to
          false.

        * `functionsNeverReturnBlobs' -- Should the driver always treat
          data from functions returning `BLOBs' as Strings. Added
          specifically to work around dubious metadata returned by the
          server for `GROUP BY' clauses. Defaults to false.

   * Setting `rewriteBatchedStatements' to `true' now causes
     CallableStatements with batched arguments to be re-written in the
     form "CALL (...); CALL (...); ..." to send the batch in as few
     client-server round trips as possible.

   * The driver now picks appropriate internal row representation
     (whole row in one buffer, or individual byte[]s for each column
     value) depending on heuristics, including whether or not the row
     has *Note `BLOB': blob. or *Note `TEXT': blob. types and the
     overall row-size. The threshold for row size that will cause the
     driver to use a buffer rather than individual byte[]s is
     configured by the configuration property `largeRowSizeThreshold',
     which has a default value of 2KB.

   * The data (and how it is stored) for `ResultSet' rows are now
     behind an interface which allows us (in some cases) to allocate
     less memory per row, in that for "streaming" result sets, we
     re-use the packet used to read rows, since only one row at a time
     is ever active.

   * Added experimental support for statement "interceptors" via the
     `com.mysql.jdbc.StatementInterceptor' interface, examples are in
     `com/mysql/jdbc/interceptors'. Implement this interface to be
     placed "in between" query execution, so that it can be influenced
     (currently experimental).

   * The driver will automatically adjust the server session variable
     `net_write_timeout' when it determines its been asked for a
     "streaming" result, and resets it to the previous value when the
     result set has been consumed.  (The configuration property is named
     `netTimeoutForStreamingResults', with a unit of seconds, the value
     '0' means the driver will not try and adjust this value).

   * JDBC-4.0 ease-of-development features including auto-registration
     with the `DriverManager' via the service provider mechanism,
     standardized Connection validity checks and categorized
     `SQLExceptions' based on recoverability/retry-ability and class of
     the underlying error.

   * `Statement.setQueryTimeout()'s now affect the entire batch for
     batched statements, rather than the individual statements that
     make up the batch.

   * Errors encountered during
     `Statement'/`PreparedStatement'/`CallableStatement.executeBatch()'
     when `rewriteBatchStatements' has been set to `true' now return
     `BatchUpdateExceptions' according to the setting of
     `continueBatchOnError'.

     If `continueBatchOnError' is set to `true', the update counts for
     the "chunk" that were sent as one unit will all be set to
     `EXECUTE_FAILED', but the driver will attempt to process the
     remainder of the batch. You can determine which "chunk" failed by
     looking at the update counts returned in the
     `BatchUpdateException'.

     If `continueBatchOnError' is set to "false", the update counts
     returned will contain all updates up-to and including the failed
     "chunk", with all counts for the failed "chunk" set to
     `EXECUTE_FAILED'.

     Since MySQL doesn't return multiple error codes for
     multiple-statements, or for multi-value *Note `INSERT':
     insert./*Note `REPLACE': replace, it is the application's
     responsibility to handle determining which item(s) in the "chunk"
     actually failed.

   * New methods on com.mysql.jdbc.Statement:
     `setLocalInfileInputStream()' and `getLocalInfileInputStream()':

        * `setLocalInfileInputStream()' sets an `InputStream' instance
          that will be used to send data to the MySQL server for a
          *Note `LOAD DATA LOCAL INFILE': load-data. statement rather
          than a `FileInputStream' or `URLInputStream' that represents
          the path given as an argument to the statement.

          This stream will be read to completion upon execution of a
          *Note `LOAD DATA LOCAL INFILE': load-data. statement, and
          will automatically be closed by the driver, so it needs to be
          reset before each call to `execute*()' that would cause the
          MySQL server to request data to fulfill the request for *Note
          `LOAD DATA LOCAL INFILE': load-data.

          If this value is set to `NULL', the driver will revert to
          using a `FileInputStream' or `URLInputStream' as required.

        * `getLocalInfileInputStream()' returns the `InputStream'
          instance that will be used to send data in response to a
          *Note `LOAD DATA LOCAL INFILE': load-data. statement.

          This method returns `NULL' if no such stream has been set via
          `setLocalInfileInputStream()'.

   * Setting `useBlobToStoreUTF8OutsideBMP' to `true' tells the driver
     to treat `[MEDIUM/LONG]BLOB' columns as `[LONG]VARCHAR' columns
     holding text encoded in UTF-8 that has characters outside the BMP
     (4-byte encodings), which MySQL server can't handle natively.

     Set `utf8OutsideBmpExcludedColumnNamePattern' to a regex so that
     column names matching the given regex will still be treated as
     `BLOBs' The regex must follow the patterns used for the
     `java.util.regex'package.  The default is to exclude no columns,
     and include all columns.

     Set `utf8OutsideBmpIncludedColumnNamePattern' to specify exclusion
     rules to utf8OutsideBmpExcludedColumnNamePattern". The regex must
     follow the patterns used for the `java.util.regex' package.

Bugs fixed:

   * `setObject(int, Object, int, int)' delegate in
     PreparedStatmentWrapper delegates to wrong method.  (Bug#30892
     (http://bugs.mysql.com/30892))

   * NPE with null column values when `padCharsWithSpace' is set to
     true.  (Bug#30851 (http://bugs.mysql.com/30851))

   * Collation on *Note `VARBINARY': binary-varbinary. column types
     would be misidentified. A fix has been added, but this fix only
     works for MySQL server versions 5.0.25 and newer, since earlier
     versions didn't consistently return correct metadata for
     functions, and thus results from subqueries and functions were
     indistinguishable from each other, leading to type-related bugs.
     (Bug#30664 (http://bugs.mysql.com/30664))

   * An `ArithmeticException' or `NullPointerException' would be raised
     when the batch had zero members and
     `rewriteBatchedStatements=true' when `addBatch()' was never
     called, or `executeBatch()' was called immediately after
     `clearBatch()'.  (Bug#30550 (http://bugs.mysql.com/30550))

   * Closing a load-balanced connection would cause a
     `ClassCastException'.  (Bug#29852 (http://bugs.mysql.com/29852))

   * Connection checker for JBoss didn't use same method parameters via
     reflection, causing connections to always seem "bad".  (Bug#29106
     (http://bugs.mysql.com/29106))

   * `DatabaseMetaData.getTypeInfo()' for the types *Note `DECIMAL':
     numeric-types. and *Note `NUMERIC': numeric-types. will return a
     precision of 254 for server versions older than 5.0.3, 64 for
     versions 5.0.3-5.0.5 and 65 for versions newer than 5.0.5.
     (Bug#28972 (http://bugs.mysql.com/28972))

   * `CallableStatement.executeBatch()' doesn't work when connection
     property `noAccessToProcedureBodies' has been set to `true'.

     The fix involves changing the behavior of
     `noAccessToProcedureBodies',in that the driver will now report all
     paramters as "IN" paramters but allow callers to call
     registerOutParameter() on them without throwing an exception.
     (Bug#28689 (http://bugs.mysql.com/28689))

   * `DatabaseMetaData.getColumns()' doesn't contain `SCOPE_*' or
     `IS_AUTOINCREMENT' columns.  (Bug#27915
     (http://bugs.mysql.com/27915))

   * Schema objects with identifiers other than the connection
     character aren't retrieved correctly in `ResultSetMetadata'.
     (Bug#27867 (http://bugs.mysql.com/27867))

   * `Connection.getServerCharacterEncoding()' doesn't work for servers
     with version >= 4.1.  (Bug#27182 (http://bugs.mysql.com/27182))

   * The automated SVN revisions in `DBMD.getDriverVersion()'. The SVN
     revision of the directory is now inserted into the version
     information during the build.  (Bug#21116
     (http://bugs.mysql.com/21116))

   * Specifying a "validation query" in your connection pool that
     starts with "/* ping */" _exactly_ will cause the driver to
     instead send a ping to the server and return a fake result set
     (much lighter weight), and when using a ReplicationConnection or a
     LoadBalancedConnection, will send the ping across all active
     connections.


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C.7.1.7 Changes in MySQL Connector/J 5.1.2 (29 June 2007)
.........................................................

This is a new Beta development release, fixing recently discovered bugs.

Functionality added or changed:

   * Setting the configuration property `rewriteBatchedStatements' to
     `true' will now cause the driver to rewrite batched prepared
     statements with more than 3 parameter sets in a batch into
     multi-statements (separated by ";") if they are not plain (that
     is, without *Note `SELECT': select. or `ON DUPLICATE KEY UPDATE'
     clauses) *Note `INSERT': insert. or *Note `REPLACE': replace.
     statements.


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C.7.1.8 Changes in MySQL Connector/J 5.1.1 (22 June 2007)
.........................................................

This is a new Alpha development release, adding new features and fixing
recently discovered bugs.

Functionality added or changed:

   * *Incompatible Change*: Pulled vendor-extension methods of
     `Connection' implementation out into an interface to support
     `java.sql.Wrapper' functionality from `ConnectionPoolDataSource'.
     The vendor extensions are javadoc'd in the
     `com.mysql.jdbc.Connection' interface.

     For those looking further into the driver implementation, it is
     not an API that is used for plugability of implementations inside
     our driver (which is why there are still references to
     `ConnectionImpl' throughout the code).

     We've also added server and client `prepareStatement()' methods
     that cover all of the variants in the JDBC API.

     `Connection.serverPrepare(String)' has been re-named to
     `Connection.serverPrepareStatement()' for consistency with
     `Connection.clientPrepareStatement()'.

   * Row navigation now causes any streams/readers open on the result
     set to be closed, as in some cases we're reading directly from a
     shared network packet and it will be overwritten by the "next" row.

   * Made it possible to retrieve prepared statement parameter bindings
     (to be used in `StatementInterceptors', primarily).

   * Externalized the descriptions of connection properties.

   * The data (and how it is stored) for `ResultSet' rows are now
     behind an interface which allows us (in some cases) to allocate
     less memory per row, in that for "streaming" result sets, we
     re-use the packet used to read rows, since only one row at a time
     is ever active.

   * Similar to `Connection', we pulled out vendor extensions to
     `Statement' into an interface named `com.mysql.Statement', and
     moved the `Statement' class into `com.mysql.StatementImpl'. The
     two methods (javadoc'd in `com.mysql.Statement' are
     `enableStreamingResults()', which already existed, and
     `disableStreamingResults()' which sets the statement instance back
     to the fetch size and result set type it had before
     `enableStreamingResults()' was called.

   * Driver now picks appropriate internal row representation (whole
     row in one buffer, or individual byte[]s for each column value)
     depending on heuristics, including whether or not the row has
     *Note `BLOB': blob. or *Note `TEXT': blob. types and the overall
     row-size. The threshold for row size that will cause the driver to
     use a buffer rather than individual byte[]s is configured by the
     configuration property `largeRowSizeThreshold', which has a default
     value of 2KB.

   * Added experimental support for statement "interceptors" via the
     `com.mysql.jdbc.StatementInterceptor' interface, examples are in
     `com/mysql/jdbc/interceptors'.

     Implement this interface to be placed "in between" query
     execution, so that you can influence it. (currently experimental).

     `StatementInterceptors' are "chainable" when configured by the
     user, the results returned by the "current" interceptor will be
     passed on to the next on in the chain, from left-to-right order,
     as specified by the user in the JDBC configuration property
     `statementInterceptors'.

   * See the sources (fully javadoc'd) for
     `com.mysql.jdbc.StatementInterceptor' for more details until we
     iron out the API and get it documented in the manual.

   * Setting `rewriteBatchedStatements' to `true' now causes
     `CallableStatements' with batched arguments to be re-written in
     the form `CALL (...); CALL (...); ...' to send the batch in as few
     client-server round trips as possible.


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C.7.1.9 Changes in MySQL Connector/J 5.1.0 (11 April 2007)
..........................................................

This is the first public alpha release of the current Connector/J 5.1
development branch, providing an insight to upcoming features. Although
some of these are still under development, this release includes the
following new features and changes (in comparison to the current
Connector/J 5.0 production release):

*Important change:* Due to a number of issues with the use of
server-side prepared statements, Connector/J 5.0.5 has disabled their
use by default.  The disabling of server-side prepared statements does
not affect the operation of the connector in any way.

To enable server-side prepared statements you must add the following
configuration property to your connector string:

     useServerPrepStmts=true

The default value of this property is `false' (that is, Connector/J
does not use server-side prepared statements).

*Note*:

The disabling of server-side prepared statements does not affect the
operation of the connector. However, if you use the `useTimezone=true'
connection option and use client-side prepared statements (instead of
server-side prepared statements) you should also set
`useSSPSCompatibleTimezoneShift=true'.

Functionality added or changed:

   * Refactored `CommunicationsException' into a JDBC-3.0 version, and
     a JDBC-4.0 version (which extends `SQLRecoverableException', now
     that it exists).

     *Note*:

     This change means that if you were catching
     `com.mysql.jdbc.CommunicationsException' in your applications
     instead of looking at the SQLState class of `08', and are moving
     to Java 6 (or newer), you need to change your imports to that
     exception to be
     `com.mysql.jdbc.exceptions.jdbc4.CommunicationsException', as the
     old class will not be instantiated for communications link-related
     errors under Java 6.

   * Added support for JDBC-4.0 categorized `SQLExceptions'.

   * Added support for JDBC-4.0's `NCLOB', and *Note `NCHAR':
     char./*Note `NVARCHAR': char.  types.

   * `com.mysql.jdbc.java6.javac' -- full path to your Java-6 `javac'
     executable

   * Added support for JDBC-4.0's SQLXML interfaces.

   * Re-worked Ant buildfile to build JDBC-4.0 classes separately, as
     well as support building under Eclipse (since Eclipse can't
     mix/match JDKs).

     To build, you must set `JAVA_HOME' to J2SDK-1.4.2 or Java-5, and
     set the following properties on your Ant command line:

        * `com.mysql.jdbc.java6.javac' -- full path to your Java-6
          `javac' executable

        * `com.mysql.jdbc.java6.rtjar' -- full path to your Java-6
          `rt.jar' file

   * New feature -- driver will automatically adjust session variable
     `net_write_timeout' when it determines it has been asked for a
     "streaming" result, and resets it to the previous value when the
     result set has been consumed. (configuration property is named
     `netTimeoutForStreamingResults' value and has a unit of seconds,
     the value `0' means the driver will not try and adjust this value).

   * Added support for JDBC-4.0's client information. The backend
     storage of information provided via `Connection.setClientInfo()'
     and retrieved by `Connection.getClientInfo()' is pluggable by any
     class that implements the `com.mysql.jdbc.JDBC4ClientInfoProvider'
     interface and has a no-args constructor.

     The implementation used by the driver is configured using the
     `clientInfoProvider' configuration property (with a default of
     value of `com.mysql.jdbc.JDBC4CommentClientInfoProvider', an
     implementation which lists the client information as a comment
     prepended to every query sent to the server).

     This functionality is only available when using Java-6 or newer.

   * `com.mysql.jdbc.java6.rtjar' -- full path to your Java-6 `rt.jar'
     file

   * Added support for JDBC-4.0's `Wrapper' interface.


File: manual.info,  Node: cj-news-5-0,  Next: cg-news-3-1,  Prev: cj-news-5-1,  Up: cj-news

C.7.2 Changes in MySQL Connector/J 5.0.x
----------------------------------------

* Menu:

* cj-news-5-0-8::                Changes in MySQL Connector/J 5.0.8 (09 October 2007)
* cj-news-5-0-7::                Changes in MySQL Connector/J 5.0.7 (20 July 2007)
* cj-news-5-0-6::                Changes in MySQL Connector/J 5.0.6 (15 May 2007)
* cj-news-5-0-5::                Changes in MySQL Connector/J 5.0.5 (02 March 2007)
* cj-news-5-0-4::                Changes in MySQL Connector/J 5.0.4 (20 October 2006)
* cj-news-5-0-3::                Changes in MySQL Connector/J 5.0.3 (26 July 2006 beta)
* cj-news-5-0-2::                Changes in MySQL Connector/J 5.0.2 (11 July 2006)
* cj-news-5-0-1::                Changes in MySQL Connector/J 5.0.1 (Not Released)
* cj-news-5-0-0::                Changes in MySQL Connector/J 5.0.0 (22 December 2005)


File: manual.info,  Node: cj-news-5-0-8,  Next: cj-news-5-0-7,  Prev: cj-news-5-0,  Up: cj-news-5-0

C.7.2.1 Changes in MySQL Connector/J 5.0.8 (09 October 2007)
............................................................

Functionality added or changed:

   * `blobsAreStrings' -- Should the driver always treat BLOBs as
     Strings. Added specifically to work around dubious metadata
     returned by the server for `GROUP BY' clauses. Defaults to false.

   * Added two configuration parameters:

        * `blobsAreStrings' -- Should the driver always treat BLOBs as
          Strings. Added specifically to work around dubious metadata
          returned by the server for `GROUP BY' clauses. Defaults to
          false.

        * `functionsNeverReturnBlobs' -- Should the driver always treat
          data from functions returning `BLOBs' as Strings. Added
          specifically to work around dubious metadata returned by the
          server for `GROUP BY' clauses. Defaults to false.

   * `functionsNeverReturnBlobs' -- Should the driver always treat data
     from functions returning `BLOBs' as Strings. Added specifically to
     work around dubious metadata returned by the server for `GROUP BY'
     clauses. Defaults to false.

   * XAConnections now start in auto-commit mode (as per JDBC-4.0
     specification clarification).

   * Driver will now fall back to sane defaults for
     `max_allowed_packet' and `net_buffer_length' if the server reports
     them incorrectly (and will log this situation at `WARN' level,
     since it is actually an error condition).

Bugs fixed:

   * Connections established using URLs of the form
     `jdbc:mysql:loadbalance://' weren't doing failover if they tried
     to connect to a MySQL server that was down. The driver now
     attempts connections to the next "best" (depending on the load
     balance strategy in use) server, and continues to attempt
     connecting to the next "best" server every 250 milliseconds until
     one is found that is up and running or 5 minutes has passed.

     If the driver gives up, it will throw the last-received
     `SQLException'.  (Bug#31053 (http://bugs.mysql.com/31053))

   * `setObject(int, Object, int, int)' delegate in
     PreparedStatmentWrapper delegates to wrong method.  (Bug#30892
     (http://bugs.mysql.com/30892))

   * NPE with null column values when `padCharsWithSpace' is set to
     true.  (Bug#30851 (http://bugs.mysql.com/30851))

   * Collation on *Note `VARBINARY': binary-varbinary. column types
     would be misidentified. A fix has been added, but this fix only
     works for MySQL server versions 5.0.25 and newer, since earlier
     versions didn't consistently return correct metadata for
     functions, and thus results from subqueries and functions were
     indistinguishable from each other, leading to type-related bugs.
     (Bug#30664 (http://bugs.mysql.com/30664))

   * An `ArithmeticException' or `NullPointerException' would be raised
     when the batch had zero members and
     `rewriteBatchedStatements=true' when `addBatch()' was never
     called, or `executeBatch()' was called immediately after
     `clearBatch()'.  (Bug#30550 (http://bugs.mysql.com/30550))

   * Closing a load-balanced connection would cause a
     `ClassCastException'.  (Bug#29852 (http://bugs.mysql.com/29852))

   * Connection checker for JBoss didn't use same method parameters via
     reflection, causing connections to always seem "bad".  (Bug#29106
     (http://bugs.mysql.com/29106))

   * `DatabaseMetaData.getTypeInfo()' for the types *Note `DECIMAL':
     numeric-types. and *Note `NUMERIC': numeric-types. will return a
     precision of 254 for server versions older than 5.0.3, 64 for
     versions 5.0.3-5.0.5 and 65 for versions newer than 5.0.5.
     (Bug#28972 (http://bugs.mysql.com/28972))

   * `CallableStatement.executeBatch()' doesn't work when connection
     property `noAccessToProcedureBodies' has been set to `true'.

     The fix involves changing the behavior of
     `noAccessToProcedureBodies',in that the driver will now report all
     paramters as "IN" paramters but allow callers to call
     registerOutParameter() on them without throwing an exception.
     (Bug#28689 (http://bugs.mysql.com/28689))

   * When a connection is in read-only mode, queries that are wrapped
     in parentheses were incorrectly identified DML statements.
     (Bug#28256 (http://bugs.mysql.com/28256))

   * `UNSIGNED' types not reported via `DBMD.getTypeInfo()', and
     capitalization of type names is not consistent between
     `DBMD.getColumns()', `RSMD.getColumnTypeName()' and
     `DBMD.getTypeInfo()'.

     This fix also ensures that the precision of `UNSIGNED MEDIUMINT'
     and `UNSIGNED BIGINT' is reported correctly via
     `DBMD.getColumns()'.  (Bug#27916 (http://bugs.mysql.com/27916))

   * `DatabaseMetaData.getColumns()' doesn't contain `SCOPE_*' or
     `IS_AUTOINCREMENT' columns.  (Bug#27915
     (http://bugs.mysql.com/27915))

   * Schema objects with identifiers other than the connection
     character aren't retrieved correctly in `ResultSetMetadata'.
     (Bug#27867 (http://bugs.mysql.com/27867))

   * Cached metadata with `PreparedStatement.execute()' throws
     `NullPointerException'.  (Bug#27412 (http://bugs.mysql.com/27412))

   * `Connection.getServerCharacterEncoding()' doesn't work for servers
     with version >= 4.1.  (Bug#27182 (http://bugs.mysql.com/27182))

   * The automated SVN revisions in `DBMD.getDriverVersion()'. The SVN
     revision of the directory is now inserted into the version
     information during the build.  (Bug#21116
     (http://bugs.mysql.com/21116))

   * Specifying a "validation query" in your connection pool that
     starts with "/* ping */" _exactly_ will cause the driver to
     instead send a ping to the server and return a fake result set
     (much lighter weight), and when using a ReplicationConnection or a
     LoadBalancedConnection, will send the ping across all active
     connections.


File: manual.info,  Node: cj-news-5-0-7,  Next: cj-news-5-0-6,  Prev: cj-news-5-0-8,  Up: cj-news-5-0

C.7.2.2 Changes in MySQL Connector/J 5.0.7 (20 July 2007)
.........................................................

Functionality added or changed:

   * The driver will now automatically set `useServerPrepStmts' to
     `true' when `useCursorFetch' has been set to `true', since the
     feature requires server-side prepared statements in order to
     function.

   * `tcpKeepAlive' - Should the driver set SO_KEEPALIVE (default
     `true')?

   * Give more information in EOFExceptions thrown out of MysqlIO (how
     many bytes the driver expected to read, how many it actually read,
     say that communications with the server were unexpectedly lost).

   * Driver detects when it is running in a ColdFusion MX server
     (tested with version 7), and uses the configuration bundle
     `coldFusion', which sets `useDynamicCharsetInfo' to `false' (see
     previous entry), and sets `useLocalSessionState' and autoReconnect
     to `true'.

   * `tcpNoDelay' - Should the driver set SO_TCP_NODELAY (disabling the
     Nagle Algorithm, default `true')?

   * Added configuration property `slowQueryThresholdNanos' - if
     `useNanosForElapsedTime' is set to `true', and this property is
     set to a non-zero value the driver will use this threshold (in
     nanosecond units) to determine if a query was slow, instead of
     using millisecond units.

   * `tcpRcvBuf' - Should the driver set SO_RCV_BUF to the given value?
     The default value of '0', means use the platform default value for
     this property.

   * Setting `useDynamicCharsetInfo' to `false' now causes driver to
     use static lookups for collations as well (makes
     ResultSetMetadata.isCaseSensitive() much more efficient, which
     leads to performance increase for ColdFusion, which calls this
     method for every column on every table it sees, it appears).

   * Added configuration properties to allow tuning of TCP/IP socket
     parameters:

        * `tcpNoDelay' - Should the driver set SO_TCP_NODELAY
          (disabling the Nagle Algorithm, default `true')?

        * `tcpKeepAlive' - Should the driver set SO_KEEPALIVE (default
          `true')?

        * `tcpRcvBuf' - Should the driver set SO_RCV_BUF to the given
          value? The default value of '0', means use the platform
          default value for this property.

        * `tcpSndBuf' - Should the driver set SO_SND_BUF to the given
          value? The default value of '0', means use the platform
          default value for this property.

        * `tcpTrafficClass' - Should the driver set traffic class or
          type-of-service fields? See the documentation for
          java.net.Socket.setTrafficClass() for more information.

   * Setting the configuration parameter `useCursorFetch' to `true' for
     MySQL-5.0+ enables the use of cursors that allow Connector/J to
     save memory by fetching result set rows in chunks (where the chunk
     size is set by calling setFetchSize() on a Statement or ResultSet)
     by using fully-materialized cursors on the server.

   * `tcpSndBuf' - Should the driver set SO_SND_BUF to the given value?
     The default value of '0', means use the platform default value for
     this property.

   * `tcpTrafficClass' - Should the driver set traffic class or
     type-of-service fields? See the documentation for
     java.net.Socket.setTrafficClass() for more information.

   * Added new debugging functionality - Setting configuration property
     `includeInnodbStatusInDeadlockExceptions' to `true' will cause the
     driver to append the output of *Note `SHOW ENGINE INNODB STATUS':
     show-engine. to deadlock-related exceptions, which will enumerate
     the current locks held inside InnoDB.

   * Added configuration property `useNanosForElapsedTime' - for
     profiling/debugging functionality that measures elapsed time,
     should the driver try to use nanoseconds resolution if available
     (requires JDK >= 1.5)?

     *Note*:

     If `useNanosForElapsedTime' is set to `true', and this property is
     set to "0" (or left default), then elapsed times will still be
     measured in nanoseconds (if possible), but the slow query
     threshold will be converted from milliseconds to nanoseconds, and
     thus have an upper bound of approximately 2000 milliseconds (as
     that threshold is represented as an integer, not a long).

Bugs fixed:

   * Don't send any file data in response to LOAD DATA LOCAL INFILE if
     the feature is disabled at the client side. This is to prevent a
     malicious server or man-in-the-middle from asking the client for
     data that the client is not expecting. Thanks to Jan Kneschke for
     discovering the exploit and Andrey "Poohie" Hristov, Konstantin
     Osipov and Sergei Golubchik for discussions about implications and
     possible fixes.  (Bug#29605 (http://bugs.mysql.com/29605))

   * Parser in client-side prepared statements runs to end of
     statement, rather than end-of-line for '#' comments. Also added
     support for '-' single-line comments.  (Bug#28956
     (http://bugs.mysql.com/28956))

   * Parser in client-side prepared statements eats character following
     '/' if it is not a multi-line comment.  (Bug#28851
     (http://bugs.mysql.com/28851))

   * PreparedStatement.getMetaData() for statements containing leading
     one-line comments is not returned correctly.

     As part of this fix, we also overhauled detection of DML for
     `executeQuery()' and *Note `SELECT': select.s for
     `executeUpdate()' in plain and prepared statements to be aware of
     the same types of comments.  (Bug#28469
     (http://bugs.mysql.com/28469))


File: manual.info,  Node: cj-news-5-0-6,  Next: cj-news-5-0-5,  Prev: cj-news-5-0-7,  Up: cj-news-5-0

C.7.2.3 Changes in MySQL Connector/J 5.0.6 (15 May 2007)
........................................................

Functionality added or changed:

   * Added an experimental load-balanced connection designed for use
     with SQL nodes in a MySQL Cluster/NDB environment (This is not for
     master-slave replication. For that, we suggest you look at
     `ReplicationConnection' or `lbpool').

     If the JDBC URL starts with
     `jdbc:mysql:loadbalance://host-1,host-2,...host-n', the driver
     will create an implementation of `java.sql.Connection' that load
     balances requests across a series of MySQL JDBC connections to the
     given hosts, where the balancing takes place after transaction
     commit.

     Therefore, for this to work (at all), you must use transactions,
     even if only reading data.

     Physical connections to the given hosts will not be created until
     needed.

     The driver will invalidate connections that it detects have had
     communication errors when processing a request. A new connection
     to the problematic host will be attempted the next time it is
     selected by the load balancing algorithm.

     There are two choices for load balancing algorithms, which may be
     specified by the `loadBalanceStrategy' JDBC URL configuration
     property:

        * `random' -- the driver will pick a random host for each
          request. This tends to work better than round-robin, as the
          randomness will somewhat account for spreading loads where
          requests vary in response time, while round-robin can
          sometimes lead to overloaded nodes if there are variations in
          response times across the workload.

        * `bestResponseTime' -- the driver will route the request to
          the host that had the best response time for the previous
          transaction.

   * `bestResponseTime' -- the driver will route the request to the
     host that had the best response time for the previous transaction.

   * Added configuration property `padCharsWithSpace' (defaults to
     `false'). If set to `true', and a result set column has the *Note
     `CHAR': char. type and the value does not fill the amount of
     characters specified in the DDL for the column, the driver will
     pad the remaining characters with space (for ANSI compliance).

   * When `useLocalSessionState' is set to `true' and connected to a
     MySQL-5.0 or later server, the JDBC driver will now determine
     whether an actual `commit' or `rollback' statement needs to be
     sent to the database when `Connection.commit()' or
     `Connection.rollback()' is called.

     This is especially helpful for high-load situations with
     connection pools that always call `Connection.rollback()' on
     connection check-in/check-out because it avoids a round-trip to
     the server.

   * Added configuration property `useDynamicCharsetInfo'. If set to
     `false' (the default), the driver will use a per-connection cache
     of character set information queried from the server when
     necessary, or when set to `true', use a built-in static mapping
     that is more efficient, but isn't aware of custom character sets or
     character sets implemented after the release of the JDBC driver.

     *Note*:

     This only affects the `padCharsWithSpace' configuration property
     and the `ResultSetMetaData.getColumnDisplayWidth()' method.

   * New configuration property, `enableQueryTimeouts' (default `true').

     When enabled, query timeouts set via `Statement.setQueryTimeout()'
     use a shared `java.util.Timer' instance for scheduling. Even if
     the timeout doesn't expire before the query is processed, there
     will be memory used by the `TimerTask' for the given timeout which
     won't be reclaimed until the time the timeout would have expired
     if it hadn't been cancelled by the driver. High-load environments
     might want to consider disabling this functionality. (this
     configuration property is part of the `maxPerformance'
     configuration bundle).

   * Give better error message when "streaming" result sets, and the
     connection gets clobbered because of exceeding `net_write_timeout'
     on the server.

   * `random' -- the driver will pick a random host for each request.
     This tends to work better than round-robin, as the randomness will
     somewhat account for spreading loads where requests vary in
     response time, while round-robin can sometimes lead to overloaded
     nodes if there are variations in response times across the
     workload.

   * `com.mysql.jdbc.[NonRegistering]Driver' now understands URLs of
     the format `jdbc:mysql:replication://' and
     `jdbc:mysql:loadbalance://' which will create a
     ReplicationConnection (exactly like when using
     `[NonRegistering]ReplicationDriver') and an experimental
     load-balanced connection designed for use with SQL nodes in a
     MySQL Cluster/NDB environment, respectively.

     In an effort to simplify things, we're working on deprecating
     multiple drivers, and instead specifying different core behavior
     based upon JDBC URL prefixes, so watch for
     `[NonRegistering]ReplicationDriver' to eventually disappear, to be
     replaced with `com.mysql.jdbc[NonRegistering]Driver' with the new
     URL prefix.

   * Fixed issue where a failed-over connection would let an
     application call `setReadOnly(false)', when that call should be
     ignored until the connection is reconnected to a writable master
     unless `failoverReadOnly' had been set to `false'.

   * Driver will now use `INSERT INTO ... VALUES (DEFAULT)'form of
     statement for updatable result sets for `ResultSet.insertRow()',
     rather than pre-populating the insert row with values from
     `DatabaseMetaData.getColumns()'(which results in a *Note `SHOW
     FULL COLUMNS': show-columns. on the server for every result set).
     If an application requires access to the default values before
     `insertRow()' has been called, the JDBC URL should be configured
     with `populateInsertRowWithDefaultValues' set to `true'.

     This fix specifically targets performance issues with ColdFusion
     and the fact that it seems to ask for updatable result sets no
     matter what the application does with them.

   * More intelligent initial packet sizes for the "shared" packets are
     used (512 bytes, rather than 16K), and initial packets used during
     handshake are now sized appropriately as to not require
     reallocation.

Bugs fixed:

   * More useful error messages are generated when the driver thinks a
     result set is not updatable. (Thanks to Ashley Martens for the
     patch).  (Bug#28085 (http://bugs.mysql.com/28085))

   * `Connection.getTransactionIsolation()' uses "`SHOW VARIABLES
     LIKE'" which is very inefficient on MySQL-5.0+ servers.
     (Bug#27655 (http://bugs.mysql.com/27655))

   * Fixed issue where calling `getGeneratedKeys()' on a prepared
     statement after calling `execute()' didn't always return the
     generated keys (`executeUpdate()' worked fine however).
     (Bug#27655 (http://bugs.mysql.com/27655))

   * `CALL /* ... */ SOME_PROC()' doesn't work.  As a side effect of
     this fix, you can now use `/* */' and `#' comments when preparing
     statements using client-side prepared statement emulation.

     If the comments happen to contain parameter markers (`?'), they
     will be treated as belonging to the comment (that is, not
     recognized) rather than being a parameter of the statement.

     *Note*:

     The statement when sent to the server will contain the comments
     as-is, they're not stripped during the process of preparing the
     `PreparedStatement' or `CallableStatement'.

     (Bug#27400 (http://bugs.mysql.com/27400))

   * `ResultSet.get*()' with a column index < 1 returns misleading
     error message.  (Bug#27317 (http://bugs.mysql.com/27317))

   * Using `ResultSet.get*()' with a column index less than 1 returns a
     misleading error message.  (Bug#27317
     (http://bugs.mysql.com/27317))

   * Comments in DDL of stored procedures/functions confuse procedure
     parser, and thus metadata about them can not be created, leading
     to inability to retrieve said metadata, or execute procedures that
     have certain comments in them.  (Bug#26959
     (http://bugs.mysql.com/26959))

   * Fast date/time parsing doesn't take into account `00:00:00' as a
     legal value.  (Bug#26789 (http://bugs.mysql.com/26789))

   * `PreparedStatement' is not closed in `BlobFromLocator.getBytes()'.
     (Bug#26592 (http://bugs.mysql.com/26592))

   * When the configuration property `useCursorFetch' was set to
     `true', sometimes server would return new, more exact metadata
     during the execution of the server-side prepared statement that
     enables this functionality, which the driver ignored (using the
     original metadata returned during `prepare()'), causing corrupt
     reading of data due to type mismatch when the actual rows were
     returned.  (Bug#26173 (http://bugs.mysql.com/26173))

   * `CallableStatements' with `OUT/INOUT' parameters that are "binary"
     (*Note `BLOB': blob, *Note `BIT': numeric-types, `(VAR)BINARY',
     `JAVA_OBJECT') have extra 7 bytes.  (Bug#25715
     (http://bugs.mysql.com/25715))

   * Whitespace surrounding storage/size specifiers in stored procedure
     parameters declaration causes `NumberFormatException' to be thrown
     when calling stored procedure on JDK-1.5 or newer, as the Number
     classes in JDK-1.5+ are whitespace intolerant.  (Bug#25624
     (http://bugs.mysql.com/25624))

   * Client options not sent correctly when using SSL, leading to
     stored procedures not being able to return results. Thanks to Don
     Cohen for the bug report, testcase and patch.  (Bug#25545
     (http://bugs.mysql.com/25545))

   * `Statement.setMaxRows()' is not effective on result sets
     materialized from cursors.  (Bug#25517
     (http://bugs.mysql.com/25517))

   * `BIT(> 1)' is returned as `java.lang.String' from
     `ResultSet.getObject()' rather than `byte[]'.  (Bug#25328
     (http://bugs.mysql.com/25328))


File: manual.info,  Node: cj-news-5-0-5,  Next: cj-news-5-0-4,  Prev: cj-news-5-0-6,  Up: cj-news-5-0

C.7.2.4 Changes in MySQL Connector/J 5.0.5 (02 March 2007)
..........................................................

Functionality added or changed:

   * Usage Advisor will now issue warnings for result sets with large
     numbers of rows. You can configure the trigger value by using the
     `resultSetSizeThreshold' parameter, which has a default value of
     100.

   * The `rewriteBatchedStatements' feature can now be used with
     server-side prepared statements.

   * *Important change:* Due to a number of issues with the use of
     server-side prepared statements, Connector/J 5.0.5 has disabled
     their use by default.  The disabling of server-side prepared
     statements does not affect the operation of the connector in any
     way.

     To enable server-side prepared statements you must add the
     following configuration property to your connector string:

          useServerPrepStmts=true

     The default value of this property is `false' (that is,
     Connector/J does not use server-side prepared statements).

   * Improved speed of `datetime' parsing for ResultSets that come from
     plain or non-server-side prepared statements. You can enable old
     implementation with `useFastDateParsing=false' as a configuration
     parameter.

   * Usage Advisor now detects empty results sets and does not report
     on columns not referenced in those empty sets.

   * Fixed logging of XA commands sent to server, it is now
     configurable via `logXaCommands' property (defaults to `false').

   * Added configuration property `localSocketAddress', which is the
     host name or IP address given to explicitly configure the
     interface that the driver will bind the client side of the TCP/IP
     connection to when connecting.

   * We've added a new configuration option `treatUtilDateAsTimestamp',
     which is `false' by default, as (1) We already had specific
     behavior to treat java.util.Date as a java.sql.Timestamp because
     it is useful to many folks, and (2) that behavior will very likely
     be required for drivers JDBC-post-4.0.

Bugs fixed:

   * Connection property `socketFactory' wasn't exposed via correctly
     named mutator/accessor, causing data source implementations that
     use JavaBean naming conventions to set properties to fail to set
     the property (and in the case of SJAS, fail silently when trying
     to set this parameter).  (Bug#26326 (http://bugs.mysql.com/26326))

   * A query execution which timed out did not always throw a
     `MySQLTimeoutException'.  (Bug#25836 (http://bugs.mysql.com/25836))

   * Storing a `java.util.Date' object in a *Note `BLOB': blob. column
     would not be serialized correctly during `setObject'.  (Bug#25787
     (http://bugs.mysql.com/25787))

   * Timer instance used for `Statement.setQueryTimeout()' created
     per-connection, rather than per-VM, causing memory leak.
     (Bug#25514 (http://bugs.mysql.com/25514))

   * `EscapeProcessor' gets confused by multiple backslashes. We now
     push the responsibility of syntax errors back on to the server for
     most escape sequences.  (Bug#25399 (http://bugs.mysql.com/25399))

   * `INOUT' parameters in `CallableStatements' get doubly-escaped.
     (Bug#25379 (http://bugs.mysql.com/25379))

   * When using the `rewriteBatchedStatements' connection option with
     `PreparedState.executeBatch()' an internal memory leak would occur.
     (Bug#25073 (http://bugs.mysql.com/25073))

   * Fixed issue where field-level for metadata from `DatabaseMetaData'
     when using `INFORMATION_SCHEMA' didn't have references to current
     connections, sometimes leading to Null Pointer Exceptions (NPEs)
     when introspecting them via `ResultSetMetaData'.  (Bug#25073
     (http://bugs.mysql.com/25073))

   * `StringUtils.indexOfIgnoreCaseRespectQuotes()' isn't
     case-insensitive on the first character of the target.  This bug
     also affected `rewriteBatchedStatements' functionality when
     prepared statements did not use uppercase for the `VALUES' clause.
     (Bug#25047 (http://bugs.mysql.com/25047))

   * Client-side prepared statement parser gets confused by in-line
     comments `/*...*/' and therefore cannot rewrite batch statements
     or reliably detect the type of statements when they are used.
     (Bug#25025 (http://bugs.mysql.com/25025))

   * Results sets from *Note `UPDATE': update.  statements that are
     part of multi-statement queries would cause an `SQLException'
     error, "Result is from UPDATE".  (Bug#25009
     (http://bugs.mysql.com/25009))

   * Specifying `US-ASCII' as the character set in a connection to a
     MySQL 4.1 or newer server does not map correctly.  (Bug#24840
     (http://bugs.mysql.com/24840))

   * Using `DatabaseMetaData.getSQLKeywords()' does not return a all of
     the of the reserved keywords for the current MySQL version.
     Current implementation returns the list of reserved words for
     MySQL 5.1, and does not distinguish between versions.  (Bug#24794
     (http://bugs.mysql.com/24794))

   * Calling `Statement.cancel()' could result in a Null Pointer
     Exception (NPE).  (Bug#24721 (http://bugs.mysql.com/24721))

   * Using `setFetchSize()' breaks prepared *Note `SHOW': show. and
     other commands.  (Bug#24360 (http://bugs.mysql.com/24360))

   * Calendars and timezones are now lazily instantiated when required.
     (Bug#24351 (http://bugs.mysql.com/24351))

   * Using *Note `DATETIME': datetime. columns would result in time
     shifts when `useServerPrepStmts' was true. The reason was due to
     different behavior when using client-side compared to server-side
     prepared statements and the `useJDBCCompliantTimezoneShift'
     option. This is now fixed if moving from server-side prepared
     statements to client-side prepared statements by setting
     `useSSPSCompatibleTimezoneShift' to `true', as the driver can't
     tell if this is a new deployment that never used server-side
     prepared statements, or if it is an existing deployment that is
     switching to client-side prepared statements from server-side
     prepared statements.  (Bug#24344 (http://bugs.mysql.com/24344))

   * Connector/J now returns a better error message when server doesn't
     return enough information to determine stored procedure/function
     parameter types.  (Bug#24065 (http://bugs.mysql.com/24065))

   * A connection error would occur when connecting to a MySQL server
     with certain character sets. Some collations/character sets
     reported as "unknown" (specifically `cias' variants of existing
     character sets), and inability to override the detected server
     character set.  (Bug#23645 (http://bugs.mysql.com/23645))

   * Inconsistency between `getSchemas' and `INFORMATION_SCHEMA'.
     (Bug#23304 (http://bugs.mysql.com/23304))

   * `DatabaseMetaData.getSchemas()' doesn't return a `TABLE_CATALOG'
     column.  (Bug#23303 (http://bugs.mysql.com/23303))

   * When using a JDBC connection URL that is malformed, the
     `NonRegisteringDriver.getPropertyInfo' method will throw a Null
     Pointer Exception (NPE).  (Bug#22628 (http://bugs.mysql.com/22628))

   * Some exceptions thrown out of `StandardSocketFactory' were
     needlessly wrapped, obscuring their true cause, especially when
     using socket timeouts.  (Bug#21480 (http://bugs.mysql.com/21480))

   * When using a server-side prepared statement the driver would send
     timestamps to the server using nanoseconds instead of milliseconds.
     (Bug#21438 (http://bugs.mysql.com/21438))

   * When using server-side prepared statements and timestamp columns,
     value would be incorrectly populated (with nanoseconds, not
     microseconds).  (Bug#21438 (http://bugs.mysql.com/21438))

   * `ParameterMetaData' throws `NullPointerException' when prepared
     SQL has a syntax error. Added `generateSimpleParameterMetadata'
     configuration property, which when set to `true' will generate
     metadata reflecting *Note `VARCHAR': char. for every parameter (the
     default is `false', which will cause an exception to be thrown if
     no parameter metadata for the statement is actually available).
     (Bug#21267 (http://bugs.mysql.com/21267))

   * Fixed an issue where `XADataSources' couldn't be bound into JNDI,
     as the `DataSourceFactory' didn't know how to create instances of
     them.

Other changes:

   * Avoid static synchronized code in JVM class libraries for dealing
     with default timezones.

   * Performance enhancement of initial character set configuration,
     driver will only send commands required to configure connection
     character set session variables if the current values on the
     server do not match what is required.

   * Re-worked stored procedure parameter parser to be more robust.
     Driver no longer requires `BEGIN' in stored procedure definition,
     but does have requirement that if a stored function begins with a
     label directly after the "returns" clause, that the label is not a
     quoted identifier.

   * Throw exceptions encountered during timeout to thread calling
     `Statement.execute*()', rather than `RuntimeException'.

   * Changed cached result set metadata (when using
     `cacheResultSetMetadata=true') to be cached per-connection rather
     than per-statement as previously implemented.

   * Reverted back to internal character conversion routines for
     single-byte character sets, as the ones internal to the JVM are
     using much more CPU time than our internal implementation.

   * When extracting foreign key information from *Note `SHOW CREATE
     TABLE': show-create-table. in `DatabaseMetaData', ignore
     exceptions relating to tables being missing (which could happen
     for cross-reference or imported-key requests, as the list of
     tables is generated first, then iterated).

   * Fixed some Null Pointer Exceptions (NPEs) when cached metadata was
     used with `UpdatableResultSets'.

   * Take `localSocketAddress' property into account when creating
     instances of `CommunicationsException' when the underyling
     exception is a `java.net.BindException', so that a friendlier
     error message is given with a little internal diagnostics.

   * Fixed cases where `ServerPreparedStatements' weren't using cached
     metadata when `cacheResultSetMetadata=true' was used.

   * Use a `java.util.TreeMap' to map column names to ordinal indexes
     for `ResultSet.findColumn()' instead of a HashMap. This allows us
     to have case-insensitive lookups (required by the JDBC
     specification) without resorting to the many transient object
     instances needed to support this requirement with a normal
     `HashMap' with either case-adjusted keys, or case-insensitive
     keys. (In the worst case scenario for lookups of a 1000 column
     result set, TreeMaps are about half as fast wall-clock time as a
     HashMap, however in normal applications their use gives many
     orders of magnitude reduction in transient object instance
     creation which pays off later for CPU usage in garbage collection).

   * When using cached metadata, skip field-level metadata packets
     coming from the server, rather than reading them and discarding
     them without creating `com.mysql.jdbc.Field' instances.


File: manual.info,  Node: cj-news-5-0-4,  Next: cj-news-5-0-3,  Prev: cj-news-5-0-5,  Up: cj-news-5-0

C.7.2.5 Changes in MySQL Connector/J 5.0.4 (20 October 2006)
............................................................

Bugs fixed:

   * DBMD.getColumns() does not return expected COLUMN_SIZE for the SET
     type, now returns length of largest possible set disregarding
     whitespace or the "," delimitters to be consistent with the ODBC
     driver.  (Bug#22613 (http://bugs.mysql.com/22613))

   * Added new _ci collations to CharsetMapping - utf8_unicode_ci not
     working.  (Bug#22456 (http://bugs.mysql.com/22456))

   * Driver was using milliseconds for Statement.setQueryTimeout() when
     specification says argument is to be in seconds.  (Bug#22359
     (http://bugs.mysql.com/22359))

   * Workaround for server crash when calling stored procedures via a
     server-side prepared statement (driver now detects prepare(stored
     procedure) and substitutes client-side prepared statement).
     (Bug#22297 (http://bugs.mysql.com/22297))

   * Driver issues truncation on write exception when it shouldn't (due
     to sending big decimal incorrectly to server with server-side
     prepared statement).  (Bug#22290 (http://bugs.mysql.com/22290))

   * Newlines causing whitespace to span confuse procedure parser when
     getting parameter metadata for stored procedures.  (Bug#22024
     (http://bugs.mysql.com/22024))

   * When using information_schema for metadata, COLUMN_SIZE for
     getColumns() is not clamped to range of java.lang.Integer as is
     the case when not using information_schema, thus leading to a
     truncation exception that isn't present when not using
     information_schema.  (Bug#21544 (http://bugs.mysql.com/21544))

   * Column names don't match metadata in cases where server doesn't
     return original column names (column functions) thus breaking
     compatibility with applications that expect 1-1 mappings between
     findColumn() and rsmd.getColumnName(), usually manifests itself as
     "Can't find column (")" exceptions.  (Bug#21379
     (http://bugs.mysql.com/21379))

   * Driver now sends numeric 1 or 0 for client-prepared statement
     `setBoolean()' calls instead of '1' or '0'.

   * Fixed configuration property `jdbcCompliantTruncation' was not
     being used for reads of result set values.

   * DatabaseMetaData correctly reports `true' for `supportsCatalog*()'
     methods.

   * Driver now supports `{call sp}' (without "()" if procedure has no
     arguments).


File: manual.info,  Node: cj-news-5-0-3,  Next: cj-news-5-0-2,  Prev: cj-news-5-0-4,  Up: cj-news-5-0

C.7.2.6 Changes in MySQL Connector/J 5.0.3 (26 July 2006 beta)
..............................................................

Functionality added or changed:

   * Added configuration option `noAccessToProcedureBodies' which will
     cause the driver to create basic parameter metadata for
     `CallableStatements' when the user does not have access to
     procedure bodies via *Note `SHOW CREATE PROCEDURE':
     show-create-procedure. or selecting from `mysql.proc' instead of
     throwing an exception.  The default value for this option is
     `false'

Bugs fixed:

   * Fixed `Statement.cancel()' causes `NullPointerException' if
     underlying connection has been closed due to server failure.
     (Bug#20650 (http://bugs.mysql.com/20650))

   * If the connection to the server has been closed due to a server
     failure, then the cleanup process will call ` Statement.cancel()',
     triggering a `NullPointerException', even though there is no
     active connection.  (Bug#20650 (http://bugs.mysql.com/20650))


File: manual.info,  Node: cj-news-5-0-2,  Next: cj-news-5-0-1,  Prev: cj-news-5-0-3,  Up: cj-news-5-0

C.7.2.7 Changes in MySQL Connector/J 5.0.2 (11 July 2006)
.........................................................

Bugs fixed:

   * `MysqlXaConnection.recover(int flags)' now allows combinations of
     `XAResource.TMSTARTRSCAN' and `TMENDRSCAN'. To simulate the
     `scanning' nature of the interface, we return all prepared XIDs
     for `TMSTARTRSCAN', and no new XIDs for calls with `TMNOFLAGS', or
     `TMENDRSCAN' when not in combination with `TMSTARTRSCAN'. This
     change was made for API compliance, as well as integration with
     IBM WebSphere's transaction manager.  (Bug#20242
     (http://bugs.mysql.com/20242))

   * Fixed `MysqlValidConnectionChecker' for JBoss doesn't work with
     `MySQLXADataSources'.  (Bug#20242 (http://bugs.mysql.com/20242))

   * Added connection/datasource property
     `pinGlobalTxToPhysicalConnection' (defaults to `false'). When set
     to `true', when using `XAConnections', the driver ensures that
     operations on a given XID are always routed to the same physical
     connection. This allows the `XAConnection' to support `XA START ...
     JOIN' after *Note `XA END': xa-statements.  has been called, and
     is also a workaround for transaction managers that don't maintain
     thread affinity for a global transaction (most either always
     maintain thread affinity, or have it as a configuration option).
     (Bug#20242 (http://bugs.mysql.com/20242))

   * Better caching of character set converters (per-connection) to
     remove a bottleneck for multibyte character sets.  (Bug#20242
     (http://bugs.mysql.com/20242))

   * Fixed `ConnectionProperties' (and thus some subclasses) are not
     serializable, even though some J2EE containers expect them to be.
     (Bug#19169 (http://bugs.mysql.com/19169))

   * Fixed driver fails on non-ASCII platforms. The driver was assuming
     that the platform character set would be a superset of MySQL's
     `latin1' when doing the handshake for authentication, and when
     reading error messages. We now use Cp1252 for all strings sent to
     the server during the handshake phase, and a hard-coded mapping of
     the `language' systtem variable to the character set that is used
     for error messages.  (Bug#18086 (http://bugs.mysql.com/18086))

   * Fixed can't use `XAConnection' for local transactions when no
     global transaction is in progress.  (Bug#17401
     (http://bugs.mysql.com/17401))


File: manual.info,  Node: cj-news-5-0-1,  Next: cj-news-5-0-0,  Prev: cj-news-5-0-2,  Up: cj-news-5-0

C.7.2.8 Changes in MySQL Connector/J 5.0.1 (Not Released)
.........................................................

Not released due to a packaging error


File: manual.info,  Node: cj-news-5-0-0,  Prev: cj-news-5-0-1,  Up: cj-news-5-0

C.7.2.9 Changes in MySQL Connector/J 5.0.0 (22 December 2005)
.............................................................

Bugs fixed:

   * Added support for Connector/MXJ integration via url subprotocol
     `jdbc:mysql:mxj://...'.  (Bug#14729 (http://bugs.mysql.com/14729))

   * Idle timeouts cause `XAConnections' to whine about rolling
     themselves back.  (Bug#14729 (http://bugs.mysql.com/14729))

   * When fix for Bug#14562 (http://bugs.mysql.com/14562) was merged
     from 3.1.12, added functionality for `CallableStatement''s
     parameter metadata to return correct information for
     `.getParameterClassName()'.  (Bug#14729
     (http://bugs.mysql.com/14729))

   * Added service-provider entry to
     `META-INF/services/java.sql.Driver' for JDBC-4.0 support.
     (Bug#14729 (http://bugs.mysql.com/14729))

   * Fuller synchronization of `Connection' to avoid deadlocks when
     using multithreaded frameworks that multithread a single
     connection (usually not recommended, but the JDBC spec allows it
     anyways), part of fix to Bug#14972 (http://bugs.mysql.com/14972)).
     (Bug#14729 (http://bugs.mysql.com/14729))

   * Moved all `SQLException' constructor usage to a factory in
     `SQLError' (ground-work for JDBC-4.0 `SQLState'-based exception
     classes).  (Bug#14729 (http://bugs.mysql.com/14729))

   * Removed Java5-specific calls to `BigDecimal' constructor (when
     result set value is `''', `(int)0' was being used as an argument
     indirectly via method return value. This signature doesn't exist
     prior to Java5.)  (Bug#14729 (http://bugs.mysql.com/14729))

   * Implementation of `Statement.cancel()' and
     `Statement.setQueryTimeout()'. Both require MySQL-5.0.0 or newer
     server, require a separate connection to issue the *Note `KILL
     QUERY': kill. statement, and in the case of `setQueryTimeout()'
     creates an additional thread to handle the timeout functionality.

     Note: Failures to cancel the statement for `setQueryTimeout()' may
     manifest themselves as `RuntimeExceptions' rather than failing
     silently, as there is currently no way to unblock the thread that
     is executing the query being cancelled due to timeout expiration
     and have it throw the exception instead.  (Bug#14729
     (http://bugs.mysql.com/14729))

   * Return "[VAR]BINARY" for `RSMD.getColumnTypeName()' when that is
     actually the type, and it can be distinguished (MySQL-4.1 and
     newer).  (Bug#14729 (http://bugs.mysql.com/14729))

   * Attempt detection of the MySQL type *Note `BINARY':
     binary-varbinary. (it is an alias, so this isn't always reliable),
     and use the `java.sql.Types.BINARY' type mapping for it.

   * Added unit tests for `XADatasource', as well as friendlier
     exceptions for XA failures compared to the "stock" `XAException'
     (which has no messages).

   * If the connection `useTimezone' is set to `true', then also
     respect time zone conversions in escape-processed string literals
     (for example, `"{ts ...}"' and `"{t ...}"').

   * Don't allow `.setAutoCommit(true)', or `.commit()' or `.rollback()'
     on an XA-managed connection as per the JDBC specification.

   * `XADataSource' implemented (ported from 3.2 branch which won't be
     released as a product). Use
     `com.mysql.jdbc.jdbc2.optional.MysqlXADataSource' as your
     datasource class name in your application server to utilize XA
     transactions in MySQL-5.0.10 and newer.

   * Moved `-bin-g.jar' file into separate `debug' subdirectory to
     avoid confusion.

   * Return original column name for `RSMD.getColumnName()' if the
     column was aliased, alias name for `.getColumnLabel()' (if
     aliased), and original table name for `.getTableName()'. Note this
     only works for MySQL-4.1 and newer, as older servers don't make
     this information available to clients.

   * Setting `useJDBCCompliantTimezoneShift=true' (it is not the
     default) causes the driver to use GMT for _all_ *Note `TIMESTAMP':
     datetime./*Note `DATETIME': datetime.  time zones, and the current
     VM time zone for any other type that refers to time zones. This
     feature can not be used when `useTimezone=true' to convert between
     server and client time zones.

   * `PreparedStatement.setString()' didn't work correctly when
     `sql_mode' on server contained `NO_BACKSLASH_ESCAPES' and no
     characters that needed escaping were present in the string.

   * Add one level of indirection of internal representation of
     `CallableStatement' parameter metadata to avoid class not found
     issues on JDK-1.3 for `ParameterMetadata' interface (which doesn't
     exist prior to JDBC-3.0).


File: manual.info,  Node: cg-news-3-1,  Next: cg-news-3-0,  Prev: cj-news-5-0,  Up: cj-news

C.7.3 Changes in MySQL Connector/J 3.1.x
----------------------------------------

* Menu:

* cj-news-3-1-15::               Changes in MySQL Connector/J 3.1.15 (Not yet released)
* cj-news-3-1-14::               Changes in MySQL Connector/J 3.1.14 (10-19-2006)
* cj-news-3-1-13::               Changes in MySQL Connector/J 3.1.13 (26 May 2006)
* cj-news-3-1-12::               Changes in MySQL Connector/J 3.1.12 (30 November 2005)
* cj-news-3-1-11::               Changes in MySQL Connector/J 3.1.11 (07 October 2005)
* cj-news-3-1-10::               Changes in MySQL Connector/J 3.1.10 (23 June 2005)
* cj-news-3-1-9::                Changes in MySQL Connector/J 3.1.9 (22 June 2005)
* cj-news-3-1-8::                Changes in MySQL Connector/J 3.1.8 (14 April 2005)
* cj-news-3-1-7::                Changes in MySQL Connector/J 3.1.7 (18 February 2005)
* cj-news-3-1-6::                Changes in MySQL Connector/J 3.1.6 (23 December 2004)
* cj-news-3-1-5::                Changes in MySQL Connector/J 3.1.5 (02 December 2004)
* cj-news-3-1-4::                Changes in MySQL Connector/J 3.1.4 (04 September 2004)
* cj-news-3-1-3::                Changes in MySQL Connector/J 3.1.3 (07 July 2004)
* cj-news-3-1-2::                Changes in MySQL Connector/J 3.1.2 (09 June 2004)
* cj-news-3-1-1::                Changes in MySQL Connector/J 3.1.1 (14 February 2004 alpha)
* cj-news-3-1-0::                Changes in MySQL Connector/J 3.1.0 (18 February 2003 alpha)


File: manual.info,  Node: cj-news-3-1-15,  Next: cj-news-3-1-14,  Prev: cg-news-3-1,  Up: cg-news-3-1

C.7.3.1 Changes in MySQL Connector/J 3.1.15 (Not yet released)
..............................................................

*Important change:* Due to a number of issues with the use of
server-side prepared statements, Connector/J 5.0.5 has disabled their
use by default.  The disabling of server-side prepared statements does
not affect the operation of the connector in any way.

To enable server-side prepared statements you must add the following
configuration property to your connector string:

     useServerPrepStmts=true

The default value of this property is `false' (that is, Connector/J
does not use server-side prepared statements).

Bugs fixed:

   * Specifying `US-ASCII' as the character set in a connection to a
     MySQL 4.1 or newer server does not map correctly.  (Bug#24840
     (http://bugs.mysql.com/24840))


File: manual.info,  Node: cj-news-3-1-14,  Next: cj-news-3-1-13,  Prev: cj-news-3-1-15,  Up: cg-news-3-1

C.7.3.2 Changes in MySQL Connector/J 3.1.14 (10-19-2006)
........................................................

Bugs fixed:

   * Check and store value for continueBatchOnError property in
     constructor of Statements, rather than when executing batches, so
     that Connections closed out from underneath statements don't cause
     NullPointerExceptions when it is required to check this property.
     (Bug#22290 (http://bugs.mysql.com/22290))

   * Fixed Bug#18258 (http://bugs.mysql.com/18258) -
     DatabaseMetaData.getTables(), columns() with bad catalog parameter
     threw exception rather than return empty result set (as required
     by spec).  (Bug#22290 (http://bugs.mysql.com/22290))

   * Driver now sends numeric 1 or 0 for client-prepared statement
     setBoolean() calls instead of '1' or '0'.  (Bug#22290
     (http://bugs.mysql.com/22290))

   * Fixed bug where driver would not advance to next host if
     roundRobinLoadBalance=true and the last host in the list is down.
     (Bug#22290 (http://bugs.mysql.com/22290))

   * Driver issues truncation on write exception when it shouldn't (due
     to sending big decimal incorrectly to server with server-side
     prepared statement).  (Bug#22290 (http://bugs.mysql.com/22290))

   * Fixed bug when calling stored functions, where parameters weren't
     numbered correctly (first parameter is now the return value,
     subsequent parameters if specified start at index "2").
     (Bug#22290 (http://bugs.mysql.com/22290))

   * Removed logger autodetection altogether, must now specify logger
     explicitly if you want to use a logger other than one that logs to
     STDERR.  (Bug#21207 (http://bugs.mysql.com/21207))

   * DDriver throws NPE when tracing prepared statements that have been
     closed (in asSQL()).  (Bug#21207 (http://bugs.mysql.com/21207))

   * ResultSet.getSomeInteger() doesn't work for BIT(>1).  (Bug#21062
     (http://bugs.mysql.com/21062))

   * Escape of quotes in client-side prepared statements parsing not
     respected. Patch covers more than bug report, including
     NO_BACKSLASH_ESCAPES being set, and stacked quote characters forms
     of escaping (that is, " or "").  (Bug#20888
     (http://bugs.mysql.com/20888))

   * Fixed can't pool server-side prepared statements, exception raised
     when re-using them.  (Bug#20687 (http://bugs.mysql.com/20687))

   * Fixed Updatable result set that contains a BIT column fails when
     server-side prepared statements are used.  (Bug#20485
     (http://bugs.mysql.com/20485))

   * Fixed updatable result set throws ClassCastException when there is
     row data and moveToInsertRow() is called.  (Bug#20479
     (http://bugs.mysql.com/20479))

   * Fixed ResultSet.getShort() for UNSIGNED TINYINT returns incorrect
     values when using server-side prepared statements.  (Bug#20306
     (http://bugs.mysql.com/20306))

   * ReplicationDriver does not always round-robin load balance
     depending on URL used for slaves list.  (Bug#19993
     (http://bugs.mysql.com/19993))

   * Fixed calling toString() on ResultSetMetaData for driver-generated
     (that is, from DatabaseMetaData method calls, or from
     getGeneratedKeys()) result sets would raise a NullPointerException.
     (Bug#19993 (http://bugs.mysql.com/19993))

   * Connection fails to localhost when using timeout and IPv6 is
     configured.  (Bug#19726 (http://bugs.mysql.com/19726))

   * ResultSet.getFloatFromString() can't retrieve values near
     Float.MIN/MAX_VALUE.  (Bug#18880 (http://bugs.mysql.com/18880))

   * Fixed memory leak with profileSQL=true.  (Bug#16987
     (http://bugs.mysql.com/16987))

   * Fixed NullPointerException in MysqlDataSourceFactory due to
     Reference containing RefAddrs with null content.  (Bug#16791
     (http://bugs.mysql.com/16791))


File: manual.info,  Node: cj-news-3-1-13,  Next: cj-news-3-1-12,  Prev: cj-news-3-1-14,  Up: cg-news-3-1

C.7.3.3 Changes in MySQL Connector/J 3.1.13 (26 May 2006)
.........................................................

Bugs fixed:

   * `Fixed PreparedStatement.setObject(int, Object, int)' doesn't
     respect scale of BigDecimals.  (Bug#19615
     (http://bugs.mysql.com/19615))

   * Fixed `ResultSet.wasNull()' returns incorrect value when
     extracting native string from server-side prepared statement
     generated result set.  (Bug#19282 (http://bugs.mysql.com/19282))

   * Fixed invalid classname returned for
     `ResultSetMetaData.getColumnClassName()' for `BIGINT type'.
     (Bug#19282 (http://bugs.mysql.com/19282))

   * Fixed case where driver wasn't reading server status correctly
     when fetching server-side prepared statement rows, which in some
     cases could cause warning counts to be off, or multiple result
     sets to not be read off the wire.  (Bug#19282
     (http://bugs.mysql.com/19282))

   * Fixed data truncation and `getWarnings()' only returns last
     warning in set.  (Bug#18740 (http://bugs.mysql.com/18740))

   * Fixed aliased column names where length of name > 251 are
     corrupted.  (Bug#18554 (http://bugs.mysql.com/18554))

   * Improved performance of retrieving `BigDecimal', `Time',
     `Timestamp' and `Date' values from server-side prepared statements
     by creating fewer short-lived instances of `Strings' when the
     native type is not an exact match for the requested type.
     (Bug#18496 (http://bugs.mysql.com/18496))

   * Added performance feature, re-writing of batched executes for
     `Statement.executeBatch()' (for all DML statements) and
     `PreparedStatement.executeBatch()' (for INSERTs with VALUE clauses
     only). Enable by using "rewriteBatchedStatements=true" in your
     JDBC URL.  (Bug#18041 (http://bugs.mysql.com/18041))

   * Fixed issue where server-side prepared statements don't cause
     truncation exceptions to be thrown when truncation happens.
     (Bug#18041 (http://bugs.mysql.com/18041))

   * Fixed `CallableStatement.registerOutParameter()' not working when
     some parameters pre-populated. Still waiting for feedback from
     JDBC experts group to determine what correct parameter count from
     `getMetaData()' should be, however.  (Bug#17898
     (http://bugs.mysql.com/17898))

   * Fixed calling `clearParameters()' on a closed prepared statement
     causes NPE.  (Bug#17587 (http://bugs.mysql.com/17587))

   * Map "latin1" on MySQL server to CP1252 for MySQL > 4.1.0.
     (Bug#17587 (http://bugs.mysql.com/17587))

   * Added additional accessor and mutator methods on
     ConnectionProperties so that DataSource users can use same naming
     as regular URL properties.  (Bug#17587
     (http://bugs.mysql.com/17587))

   * Fixed `ResultSet.wasNull()' not always reset correctly for
     booleans when done via conversion for server-side prepared
     statements.  (Bug#17450 (http://bugs.mysql.com/17450))

   * Fixed `Statement.getGeneratedKeys()' throws `NullPointerException'
     when no query has been processed.  (Bug#17099
     (http://bugs.mysql.com/17099))

   * Fixed updatable result set doesn't return `AUTO_INCREMENT' values
     for `insertRow()' when multiple column primary keys are used. (the
     driver was checking for the existence of single-column primary
     keys and an autoincrement value > 0 instead of a straightforward
     `isAutoIncrement()' check).  (Bug#16841
     (http://bugs.mysql.com/16841))

   * `DBMD.getColumns()' returns wrong type for *Note `BIT':
     numeric-types.  (Bug#15854 (http://bugs.mysql.com/15854))

   * `lib-nodist' directory missing from package breaks out-of-box
     build.  (Bug#15676 (http://bugs.mysql.com/15676))

   * Fixed issue with `ReplicationConnection' incorrectly copying
     state, doesn't transfer connection context correctly when
     transitioning between the same read-only states.  (Bug#15570
     (http://bugs.mysql.com/15570))

   * No "dos" character set in MySQL > 4.1.0.  (Bug#15544
     (http://bugs.mysql.com/15544))

   * `INOUT' parameter does not store `IN' value.  (Bug#15464
     (http://bugs.mysql.com/15464))

   * `PreparedStatement.setObject()' serializes `BigInteger' as object,
     rather than sending as numeric value (and is thus not
     complementary to `.getObject()' on an `UNSIGNED LONG' type).
     (Bug#15383 (http://bugs.mysql.com/15383))

   * Fixed issue where driver was unable to initialize character set
     mapping tables. Removed reliance on `.properties' files to hold
     this information, as it turns out to be too problematic to code
     around class loader hierarchies that change depending on how an
     application is deployed. Moved information back into the
     `CharsetMapping' class.  (Bug#14938 (http://bugs.mysql.com/14938))

   * Exception thrown for new decimal type when using updatable result
     sets.  (Bug#14609 (http://bugs.mysql.com/14609))

   * Driver now aware of fix for *Note `BIT': numeric-types.  type
     metadata that went into MySQL-5.0.21 for server not reporting
     length consistently .  (Bug#13601 (http://bugs.mysql.com/13601))

   * Added support for Apache Commons logging, use
     "com.mysql.jdbc.log.CommonsLogger" as the value for the "logger"
     configuration property.  (Bug#13469 (http://bugs.mysql.com/13469))

   * Fixed driver trying to call methods that don't exist on older and
     newer versions of Log4j. The fix is not trying to auto-detect
     presence of log4j, too many different incompatible versions out
     there in the wild to do this reliably.

     If you relied on autodetection before, you will need to add
     "logger=com.mysql.jdbc.log.Log4JLogger" to your JDBC URL to enable
     Log4J usage, or alternatively use the new "CommonsLogger" class to
     take care of this.  (Bug#13469 (http://bugs.mysql.com/13469))

   * LogFactory now prepends "com.mysql.jdbc.log" to log class name if
     it can't be found as-specified. This allows you to use "short
     names" for the built-in log factories, for example
     "logger=CommonsLogger" instead of
     "logger=com.mysql.jdbc.log.CommonsLogger".  (Bug#13469
     (http://bugs.mysql.com/13469))

   * `ResultSet.getShort()' for `UNSIGNED TINYINT' returned wrong
     values.  (Bug#11874 (http://bugs.mysql.com/11874))


File: manual.info,  Node: cj-news-3-1-12,  Next: cj-news-3-1-11,  Prev: cj-news-3-1-13,  Up: cg-news-3-1

C.7.3.4 Changes in MySQL Connector/J 3.1.12 (30 November 2005)
..............................................................

Bugs fixed:

   * Process escape tokens in `Connection.prepareStatement(...)'. You
     can disable this behavior by setting the JDBC URL configuration
     property `processEscapeCodesForPrepStmts' to `false'.  (Bug#15141
     (http://bugs.mysql.com/15141))

   * Usage advisor complains about unreferenced columns, even though
     they've been referenced.  (Bug#15065 (http://bugs.mysql.com/15065))

   * Driver incorrectly closes streams passed as arguments to
     `PreparedStatements'. Reverts to legacy behavior by setting the
     JDBC configuration property `autoClosePStmtStreams' to `true'
     (also included in the 3-0-Compat configuration `bundle').
     (Bug#15024 (http://bugs.mysql.com/15024))

   * Deadlock while closing server-side prepared statements from
     multiple threads sharing one connection.  (Bug#14972
     (http://bugs.mysql.com/14972))

   * Unable to initialize character set mapping tables (due to J2EE
     classloader differences).  (Bug#14938
     (http://bugs.mysql.com/14938))

   * Escape processor replaces quote character in quoted string with
     string delimiter.  (Bug#14909 (http://bugs.mysql.com/14909))

   * `DatabaseMetaData.getColumns()' doesn't return `TABLE_NAME'
     correctly.  (Bug#14815 (http://bugs.mysql.com/14815))

   * `storesMixedCaseIdentifiers()' returns `false' (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesLowerCaseIdentifiers()' returns `true' (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesMixedCaseQuotedIdentifiers()' returns `false' (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesMixedCaseQuotedIdentifiers()' returns `true' (Bug#14562
     (http://bugs.mysql.com/14562))

   * If `lower_case_table_names=0' (on server):

        * `storesLowerCaseIdentifiers()' returns `false'

        * `storesLowerCaseQuotedIdentifiers()' returns `false'

        * `storesMixedCaseIdentifiers()' returns `true'

        * `storesMixedCaseQuotedIdentifiers()' returns `true'

        * `storesUpperCaseIdentifiers()' returns `false'

        * `storesUpperCaseQuotedIdentifiers()' returns `true'

     (Bug#14562 (http://bugs.mysql.com/14562))

   * `storesUpperCaseIdentifiers()' returns `false' (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesUpperCaseQuotedIdentifiers()' returns `true' (Bug#14562
     (http://bugs.mysql.com/14562))

   * If `lower_case_table_names=1' (on server):

        * `storesLowerCaseIdentifiers()' returns `true'

        * `storesLowerCaseQuotedIdentifiers()' returns `true'

        * `storesMixedCaseIdentifiers()' returns `false'

        * `storesMixedCaseQuotedIdentifiers()' returns `false'

        * `storesUpperCaseIdentifiers()' returns `false'

        * `storesUpperCaseQuotedIdentifiers()' returns `true'

     (Bug#14562 (http://bugs.mysql.com/14562))

   * `storesLowerCaseQuotedIdentifiers()' returns `true' (Bug#14562
     (http://bugs.mysql.com/14562))

   * Fixed `DatabaseMetaData.stores*Identifiers()':

        * If `lower_case_table_names=0' (on server):

             * `storesLowerCaseIdentifiers()' returns `false'

             * `storesLowerCaseQuotedIdentifiers()' returns `false'

             * `storesMixedCaseIdentifiers()' returns `true'

             * `storesMixedCaseQuotedIdentifiers()' returns `true'

             * `storesUpperCaseIdentifiers()' returns `false'

             * `storesUpperCaseQuotedIdentifiers()' returns `true'

        * If `lower_case_table_names=1' (on server):

             * `storesLowerCaseIdentifiers()' returns `true'

             * `storesLowerCaseQuotedIdentifiers()' returns `true'

             * `storesMixedCaseIdentifiers()' returns `false'

             * `storesMixedCaseQuotedIdentifiers()' returns `false'

             * `storesUpperCaseIdentifiers()' returns `false'

             * `storesUpperCaseQuotedIdentifiers()' returns `true'

     (Bug#14562 (http://bugs.mysql.com/14562))

   * `storesMixedCaseIdentifiers()' returns `true' (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesLowerCaseQuotedIdentifiers()' returns `false' (Bug#14562
     (http://bugs.mysql.com/14562))

   * Java type conversion may be incorrect for *Note `MEDIUMINT':
     numeric-types.  (Bug#14562 (http://bugs.mysql.com/14562))

   * `storesLowerCaseIdentifiers()' returns `false' (Bug#14562
     (http://bugs.mysql.com/14562))

   * Added configuration property `useGmtMillisForDatetimes' which when
     set to `true' causes `ResultSet.getDate()', `.getTimestamp()' to
     return correct millis-since GMT when `.getTime()' is called on the
     return value (currently default is `false' for legacy behavior).
     (Bug#14562 (http://bugs.mysql.com/14562))

   * Extraneous sleep on `autoReconnect'.  (Bug#13775
     (http://bugs.mysql.com/13775))

   * Reconnect during middle of `executeBatch()' should not occur if
     `autoReconnect' is enabled.  (Bug#13255
     (http://bugs.mysql.com/13255))

   * `maxQuerySizeToLog' is not respected. Added logging of bound
     values for `execute()' phase of server-side prepared statements
     when `profileSQL=true' as well.  (Bug#13048
     (http://bugs.mysql.com/13048))

   * OpenOffice expects `DBMD.supportsIntegrityEnhancementFacility()'
     to return `true' if foreign keys are supported by the datasource,
     even though this method also covers support for check constraints,
     which MySQL _doesn't_ have. Setting the configuration property
     `overrideSupportsIntegrityEnhancementFacility' to `true' causes
     the driver to return `true' for this method.  (Bug#12975
     (http://bugs.mysql.com/12975))

   * Added `com.mysql.jdbc.testsuite.url.default' system property to
     set default JDBC url for testsuite (to speed up bug resolution
     when I'm working in Eclipse).  (Bug#12975
     (http://bugs.mysql.com/12975))

   * `logSlowQueries' should give better info.  (Bug#12230
     (http://bugs.mysql.com/12230))

   * Don't increase timeout for failover/reconnect.  (Bug#6577
     (http://bugs.mysql.com/6577))

   * Fixed client-side prepared statement bug with embedded `?'
     characters inside quoted identifiers (it was recognized as a
     placeholder, when it was not).

   * Don't allow `executeBatch()' for `CallableStatements' with
     registered `OUT'/`INOUT' parameters (JDBC compliance).

   * Fall back to platform-encoding for `URLDecoder.decode()' when
     parsing driver URL properties if the platform doesn't have a
     two-argument version of this method.


File: manual.info,  Node: cj-news-3-1-11,  Next: cj-news-3-1-10,  Prev: cj-news-3-1-12,  Up: cg-news-3-1

C.7.3.5 Changes in MySQL Connector/J 3.1.11 (07 October 2005)
.............................................................

Bugs fixed:

   * The configuration property `sessionVariables' now allows you to
     specify variables that start with the ``@'' sign.  (Bug#13453
     (http://bugs.mysql.com/13453))

   * URL configuration parameters don't allow ``&'' or ``='' in their
     values. The JDBC driver now parses configuration parameters as if
     they are encoded using the application/x-www-form-urlencoded
     format as specified by `java.net.URLDecoder'
     (`http://java.sun.com/j2se/1.5.0/docs/api/java/net/URLDecoder.html').

     If the ``%'' character is present in a configuration property, it
     must now be represented as `%25', which is the encoded form of
     ``%'' when using application/x-www-form-urlencoded encoding.
     (Bug#13453 (http://bugs.mysql.com/13453))

   * Workaround for Bug#13374 (http://bugs.mysql.com/13374):
     `ResultSet.getStatement()' on closed result set returns `NULL' (as
     per JDBC 4.0 spec, but not backward-compatible). Set the
     connection property `retainStatementAfterResultSetClose' to `true'
     to be able to retrieve a `ResultSet''s statement after the
     `ResultSet' has been closed via `.getStatement()' (the default is
     `false', to be JDBC-compliant and to reduce the chance that code
     using JDBC leaks `Statement' instances).  (Bug#13277
     (http://bugs.mysql.com/13277))

   * `ResultSetMetaData' from `Statement.getGeneratedKeys()' caused a
     `NullPointerException' to be thrown whenever a method that
     required a connection reference was called.  (Bug#13277
     (http://bugs.mysql.com/13277))

   * Backport of `VAR[BINARY|CHAR] [BINARY]' types detection from 5.0
     branch.  (Bug#13277 (http://bugs.mysql.com/13277))

   * Fixed `NullPointerException' when converting `catalog' parameter
     in many `DatabaseMetaDataMethods' to `byte[]'s (for the result
     set) when the parameter is `null'. (`null' isn't technically
     allowed by the JDBC specification, but we've historically allowed
     it).  (Bug#13277 (http://bugs.mysql.com/13277))

   * Backport of `Field' class,
     `ResultSetMetaData.getColumnClassName()', and
     `ResultSet.getObject(int)' changes from 5.0 branch to fix behavior
     surrounding `VARCHAR BINARY'/*Note `VARBINARY': binary-varbinary.
     and related types.  (Bug#13277 (http://bugs.mysql.com/13277))

   * Read response in `MysqlIO.sendFileToServer()', even if the local
     file can't be opened, otherwise next query issued will fail,
     because it is reading the response to the empty *Note `LOAD DATA
     INFILE': load-data. packet sent to the server.  (Bug#13277
     (http://bugs.mysql.com/13277))

   * When `gatherPerfMetrics' is enabled for servers older than 4.1.0,
     a `NullPointerException' is thrown from the constructor of
     `ResultSet' if the query doesn't use any tables.  (Bug#13043
     (http://bugs.mysql.com/13043))

   * `java.sql.Types.OTHER' returned for *Note `BINARY':
     binary-varbinary. and *Note `VARBINARY': binary-varbinary. columns
     when using `DatabaseMetaData.getColumns()'.  (Bug#12970
     (http://bugs.mysql.com/12970))

   * `ServerPreparedStatement.getBinding()' now checks if the statement
     is closed before attempting to reference the list of parameter
     bindings, to avoid throwing a `NullPointerException'.  (Bug#12970
     (http://bugs.mysql.com/12970))

   * Tokenizer for `=' in URL properties was causing
     `sessionVariables=....' to be parameterized incorrectly.
     (Bug#12753 (http://bugs.mysql.com/12753))

   * `cp1251' incorrectly mapped to `win1251' for servers newer than
     4.0.x.  (Bug#12752 (http://bugs.mysql.com/12752))

   * `getExportedKeys()' (Bug#12541 (http://bugs.mysql.com/12541))

   * Specifying a catalog works as stated in the API docs.  (Bug#12541
     (http://bugs.mysql.com/12541))

   * Specifying `NULL' means that catalog will not be used to filter
     the results (thus all databases will be searched), unless you've
     set `nullCatalogMeansCurrent=true' in your JDBC URL properties.
     (Bug#12541 (http://bugs.mysql.com/12541))

   * `getIndexInfo()' (Bug#12541 (http://bugs.mysql.com/12541))

   * `getProcedures()' (and thus indirectly `getProcedureColumns()')
     (Bug#12541 (http://bugs.mysql.com/12541))

   * `getImportedKeys()' (Bug#12541 (http://bugs.mysql.com/12541))

   * Specifying `""' means `current' catalog, even though this isn't
     quite JDBC spec compliant, it is there for legacy users.
     (Bug#12541 (http://bugs.mysql.com/12541))

   * `getCrossReference()' (Bug#12541 (http://bugs.mysql.com/12541))

   * Added `Connection.isMasterConnection()' for clients to be able to
     determine if a multi-host master/slave connection is connected to
     the first host in the list.  (Bug#12541
     (http://bugs.mysql.com/12541))

   * `getColumns()' (Bug#12541 (http://bugs.mysql.com/12541))

   * Handling of catalog argument in `DatabaseMetaData.getIndexInfo()',
     which also means changes to the following methods in
     `DatabaseMetaData':

        * `getBestRowIdentifier()'

        * `getColumns()'

        * `getCrossReference()'

        * `getExportedKeys()'

        * `getImportedKeys()'

        * `getIndexInfo()'

        * `getPrimaryKeys()'

        * `getProcedures()' (and thus indirectly
          `getProcedureColumns()')

        * `getTables()'

     The `catalog' argument in all of these methods now behaves in the
     following way:

        * Specifying `NULL' means that catalog will not be used to
          filter the results (thus all databases will be searched),
          unless you've set `nullCatalogMeansCurrent=true' in your JDBC
          URL properties.

        * Specifying `""' means `current' catalog, even though this
          isn't quite JDBC spec compliant, it is there for legacy users.

        * Specifying a catalog works as stated in the API docs.

        * Made `Connection.clientPrepare()' available from `wrapped'
          connections in the `jdbc2.optional' package (connections built
          by `ConnectionPoolDataSource' instances).

     (Bug#12541 (http://bugs.mysql.com/12541))

   * `getBestRowIdentifier()' (Bug#12541 (http://bugs.mysql.com/12541))

   * Made `Connection.clientPrepare()' available from `wrapped'
     connections in the `jdbc2.optional' package (connections built by
     `ConnectionPoolDataSource' instances).  (Bug#12541
     (http://bugs.mysql.com/12541))

   * `getTables()' (Bug#12541 (http://bugs.mysql.com/12541))

   * `getPrimaryKeys()' (Bug#12541 (http://bugs.mysql.com/12541))

   * `Connection.prepareCall()' is database name case-sensitive (on
     Windows systems).  (Bug#12417 (http://bugs.mysql.com/12417))

   * `explainSlowQueries' hangs with server-side prepared statements.
     (Bug#12229 (http://bugs.mysql.com/12229))

   * Properties shared between master and slave with replication
     connection.  (Bug#12218 (http://bugs.mysql.com/12218))

   * Geometry types not handled with server-side prepared statements.
     (Bug#12104 (http://bugs.mysql.com/12104))

   * `maxPerformance.properties' mis-spells `elideSetAutoCommits'.
     (Bug#11976 (http://bugs.mysql.com/11976))

   * `ReplicationConnection' won't switch to slave, throws `Catalog
     can't be null' exception.  (Bug#11879
     (http://bugs.mysql.com/11879))

   * `Pstmt.setObject(...., Types.BOOLEAN)' throws exception.
     (Bug#11798 (http://bugs.mysql.com/11798))

   * Escape tokenizer doesn't respect stacked single quotes for escapes.
     (Bug#11797 (http://bugs.mysql.com/11797))

   * `GEOMETRY' type not recognized when using server-side prepared
     statements.  (Bug#11797 (http://bugs.mysql.com/11797))

   * Foreign key information that is quoted is parsed incorrectly when
     `DatabaseMetaData' methods use that information.  (Bug#11781
     (http://bugs.mysql.com/11781))

   * The `sendBlobChunkSize' property is now clamped to
     `max_allowed_packet' with consideration of stream buffer size and
     packet headers to avoid `PacketTooBigExceptions' when
     `max_allowed_packet' is similar in size to the default
     `sendBlobChunkSize' which is 1M.  (Bug#11781
     (http://bugs.mysql.com/11781))

   * `CallableStatement.clearParameters()' now clears resources
     associated with `INOUT'/`OUTPUT' parameters as well as `INPUT'
     parameters.  (Bug#11781 (http://bugs.mysql.com/11781))

   * Fixed regression caused by fix for Bug#11552
     (http://bugs.mysql.com/11552) that caused driver to return
     incorrect values for unsigned integers when those integers where
     within the range of the positive signed type.  (Bug#11663
     (http://bugs.mysql.com/11663))

   * Moved source code to Subversion repository.  (Bug#11663
     (http://bugs.mysql.com/11663))

   * Incorrect generation of testcase scripts for server-side prepared
     statements.  (Bug#11663 (http://bugs.mysql.com/11663))

   * Fixed statements generated for testcases missing `;' for `plain'
     statements.  (Bug#11629 (http://bugs.mysql.com/11629))

   * Spurious `!' on console when character encoding is `utf8'.
     (Bug#11629 (http://bugs.mysql.com/11629))

   * `StringUtils.getBytes()' doesn't work when using multi-byte
     character encodings and a length in _characters_ is specified.
     (Bug#11614 (http://bugs.mysql.com/11614))

   * `DBMD.storesLower/Mixed/UpperIdentifiers()' reports incorrect
     values for servers deployed on Windows.  (Bug#11575
     (http://bugs.mysql.com/11575))

   * Reworked `Field' class, `*Buffer', and `MysqlIO' to be aware of
     field lengths > `Integer.MAX_VALUE'.  (Bug#11498
     (http://bugs.mysql.com/11498))

   * Escape processor didn't honor strings demarcated with double
     quotes.  (Bug#11498 (http://bugs.mysql.com/11498))

   * Updated `DBMD.supportsCorrelatedQueries()' to return `true' for
     versions > 4.1, `supportsGroupByUnrelated()' to return `true' and
     `getResultSetHoldability()' to return `HOLD_CURSORS_OVER_COMMIT'.
     (Bug#11498 (http://bugs.mysql.com/11498))

   * Lifted restriction of changing streaming parameters with
     server-side prepared statements. As long as `all' streaming
     parameters were set before execution, `.clearParameters()' does
     not have to be called. (due to limitation of client/server
     protocol, prepared statements can not reset _individual_ stream
     data on the server side).  (Bug#11498
     (http://bugs.mysql.com/11498))

   * `ResultSet.moveToCurrentRow()' fails to work when preceded by a
     call to `ResultSet.moveToInsertRow()'.  (Bug#11190
     (http://bugs.mysql.com/11190))

   * *Note `VARBINARY': binary-varbinary. data corrupted when using
     server-side prepared statements and `.setBytes()'.  (Bug#11115
     (http://bugs.mysql.com/11115))

   * `Statement.getWarnings()' fails with NPE if statement has been
     closed.  (Bug#10630 (http://bugs.mysql.com/10630))

   * Only get `char[]' from SQL in `PreparedStatement.ParseInfo()' when
     needed.  (Bug#10630 (http://bugs.mysql.com/10630))


File: manual.info,  Node: cj-news-3-1-10,  Next: cj-news-3-1-9,  Prev: cj-news-3-1-11,  Up: cg-news-3-1

C.7.3.6 Changes in MySQL Connector/J 3.1.10 (23 June 2005)
..........................................................

Bugs fixed:

   * Initial implemention of `ParameterMetadata' for
     `PreparedStatement.getParameterMetadata()'.  Only works fully for
     `CallableStatements', as current server-side prepared statements
     return every parameter as a *Note `VARCHAR': char. type.

   * Fixed connecting without a database specified raised an exception
     in `MysqlIO.changeDatabaseTo()'.


File: manual.info,  Node: cj-news-3-1-9,  Next: cj-news-3-1-8,  Prev: cj-news-3-1-10,  Up: cg-news-3-1

C.7.3.7 Changes in MySQL Connector/J 3.1.9 (22 June 2005)
.........................................................

Bugs fixed:

   * Production package doesn't include JBoss integration classes.
     (Bug#11411 (http://bugs.mysql.com/11411))

   * Removed nonsensical `costly type conversion' warnings when using
     usage advisor.  (Bug#11411 (http://bugs.mysql.com/11411))

   * Fixed `PreparedStatement.setClob()' not accepting `null' as a
     parameter.  (Bug#11360 (http://bugs.mysql.com/11360))

   * Connector/J dumping query into `SQLException' twice.  (Bug#11360
     (http://bugs.mysql.com/11360))

   * `autoReconnect' ping causes exception on connection startup.
     (Bug#11259 (http://bugs.mysql.com/11259))

   * `Connection.setCatalog()' is now aware of the
     `useLocalSessionState' configuration property, which when set to
     `true' will prevent the driver from sending `USE ...' to the
     server if the requested catalog is the same as the current catalog.
     (Bug#11115 (http://bugs.mysql.com/11115))

   * `3-0-Compat' -- Compatibility with Connector/J 3.0.x functionality
     (Bug#11115 (http://bugs.mysql.com/11115))

   * `maxPerformance' -- maximum performance without being reckless
     (Bug#11115 (http://bugs.mysql.com/11115))

   * `solarisMaxPerformance' -- maximum performance for Solaris, avoids
     syscalls where it can (Bug#11115 (http://bugs.mysql.com/11115))

   * Added `maintainTimeStats' configuration property (defaults to
     `true'), which tells the driver whether or not to keep track of
     the last query time and the last successful packet sent to the
     server's time. If set to `false', removes two syscalls per query.
     (Bug#11115 (http://bugs.mysql.com/11115))

   * *Note `VARBINARY': binary-varbinary. data corrupted when using
     server-side prepared statements and `ResultSet.getBytes()'.
     (Bug#11115 (http://bugs.mysql.com/11115))

   * Added the following configuration bundles, use one or many via the
     `useConfigs' configuration property:

        * `maxPerformance' -- maximum performance without being reckless

        * `solarisMaxPerformance' -- maximum performance for Solaris,
          avoids syscalls where it can

        * `3-0-Compat' -- Compatibility with Connector/J 3.0.x
          functionality

     (Bug#11115 (http://bugs.mysql.com/11115))

   * Try to handle `OutOfMemoryErrors' more gracefully. Although not
     much can be done, they will in most cases close the connection
     they happened on so that further operations don't run into a
     connection in some unknown state.  When an OOM has happened, any
     further operations on the connection will fail with a `Connection
     closed' exception that will also list the OOM exception as the
     reason for the implicit connection close event.  (Bug#10850
     (http://bugs.mysql.com/10850))

   * Setting `cachePrepStmts=true' now causes the `Connection' to also
     cache the check the driver performs to determine if a prepared
     statement can be server-side or not, as well as caches server-side
     prepared statements for the lifetime of a connection. As before,
     the `prepStmtCacheSize' parameter controls the size of these
     caches.  (Bug#10850 (http://bugs.mysql.com/10850))

   * Don't send `COM_RESET_STMT' for each execution of a server-side
     prepared statement if it isn't required.  (Bug#10850
     (http://bugs.mysql.com/10850))

   * 0-length streams not sent to server when using server-side
     prepared statements.  (Bug#10850 (http://bugs.mysql.com/10850))

   * Driver detects if you're running MySQL-5.0.7 or later, and does
     not scan for `LIMIT ?[,?]' in statements being prepared, as the
     server supports those types of queries now.  (Bug#10850
     (http://bugs.mysql.com/10850))

   * Reorganized directory layout. Sources now are in `src' folder.
     Don't pollute parent directory when building, now output goes to
     `./build', distribution goes to `./dist'.  (Bug#10496
     (http://bugs.mysql.com/10496))

   * Added support/bug hunting feature that generates `.sql' test
     scripts to `STDERR' when `autoGenerateTestcaseScript' is set to
     `true'.  (Bug#10496 (http://bugs.mysql.com/10496))

   * `SQLException' is thrown when using property `characterSetResults'
     with `cp932' or `eucjpms'.  (Bug#10496
     (http://bugs.mysql.com/10496))

   * The datatype returned for `TINYINT(1)' columns when
     `tinyInt1isBit=true' (the default) can be switched between
     `Types.BOOLEAN' and `Types.BIT' using the new configuration
     property `transformedBitIsBoolean', which defaults to `false'. If
     set to `false' (the default), `DatabaseMetaData.getColumns()' and
     `ResultSetMetaData.getColumnType()' will return `Types.BOOLEAN' for
     `TINYINT(1)' columns. If `true', `Types.BOOLEAN' will be returned
     instead. Regardless of this configuration property, if
     `tinyInt1isBit' is enabled, columns with the type `TINYINT(1)'
     will be returned as `java.lang.Boolean' instances from
     `ResultSet.getObject(...)', and
     `ResultSetMetaData.getColumnClassName()' will return
     `java.lang.Boolean'.  (Bug#10485 (http://bugs.mysql.com/10485))

   * `SQLException' thrown when retrieving `YEAR(2)' with
     `ResultSet.getString()'. The driver will now always treat *Note
     `YEAR': year. types as `java.sql.Dates' and return the correct
     values for `getString()'. Alternatively, the `yearIsDateType'
     connection property can be set to `false' and the values will be
     treated as `SHORT's.  (Bug#10485 (http://bugs.mysql.com/10485))

   * Driver doesn't support `{?=CALL(...)}' for calling stored
     functions. This involved adding support for function retrieval to
     `DatabaseMetaData.getProcedures()' and `getProcedureColumns()' as
     well.  (Bug#10310 (http://bugs.mysql.com/10310))

   * Unsigned *Note `SMALLINT': numeric-types. treated as signed for
     `ResultSet.getInt()', fixed all cases for `UNSIGNED' integer
     values and server-side prepared statements, as well as
     `ResultSet.getObject()' for `UNSIGNED TINYINT'.  (Bug#10156
     (http://bugs.mysql.com/10156))

   * Made `ServerPreparedStatement.asSql()' work correctly so
     auto-explain functionality would work with server-side prepared
     statements.  (Bug#10155 (http://bugs.mysql.com/10155))

   * Double quotes not recognized when parsing client-side prepared
     statements.  (Bug#10155 (http://bugs.mysql.com/10155))

   * Made JDBC2-compliant wrappers public in order to allow access to
     vendor extensions.  (Bug#10155 (http://bugs.mysql.com/10155))

   * `DatabaseMetaData.supportsMultipleOpenResults()' now returns
     `true'. The driver has supported this for some time, DBMD just
     missed that fact.  (Bug#10155 (http://bugs.mysql.com/10155))

   * Cleaned up logging of profiler events, moved code to dump a
     profiler event as a string to `com.mysql.jdbc.log.LogUtils' so
     that third parties can use it.  (Bug#10155
     (http://bugs.mysql.com/10155))

   * Made `enableStreamingResults()' visible on
     `com.mysql.jdbc.jdbc2.optional.StatementWrapper'.  (Bug#10155
     (http://bugs.mysql.com/10155))

   * Actually write manifest file to correct place so it ends up in the
     binary jar file.  (Bug#10144 (http://bugs.mysql.com/10144))

   * Added `createDatabaseIfNotExist' property (default is `false'),
     which will cause the driver to ask the server to create the
     database specified in the URL if it doesn't exist. You must have
     the appropriate privileges for database creation for this to work.
     (Bug#10144 (http://bugs.mysql.com/10144))

   * Memory leak in `ServerPreparedStatement' if `serverPrepare()'
     fails.  (Bug#10144 (http://bugs.mysql.com/10144))

   * `com.mysql.jdbc.PreparedStatement.ParseInfo' does unnecessary call
     to `toCharArray()'.  (Bug#9064 (http://bugs.mysql.com/9064))

   * Driver now correctly uses CP932 if available on the server for
     Windows-31J, CP932 and MS932 java encoding names, otherwise it
     resorts to SJIS, which is only a close approximation. Currently
     only MySQL-5.0.3 and newer (and MySQL-4.1.12 or .13, depending on
     when the character set gets backported) can reliably support any
     variant of CP932.

   * Overhaul of character set configuration, everything now lives in a
     properties file.


File: manual.info,  Node: cj-news-3-1-8,  Next: cj-news-3-1-7,  Prev: cj-news-3-1-9,  Up: cg-news-3-1

C.7.3.8 Changes in MySQL Connector/J 3.1.8 (14 April 2005)
..........................................................

Bugs fixed:

   * Should accept `null' for catalog (meaning use current) in DBMD
     methods, even though it is not JDBC-compliant for legacy's sake.
     Disable by setting connection property `nullCatalogMeansCurrent' to
     `false' (which will be the default value in C/J 3.2.x).  (Bug#9917
     (http://bugs.mysql.com/9917))

   * Fixed driver not returning `true' for `-1' when
     `ResultSet.getBoolean()' was called on result sets returned from
     server-side prepared statements.  (Bug#9778
     (http://bugs.mysql.com/9778))

   * Added a `Manifest.MF' file with implementation information to the
     `.jar' file.  (Bug#9778 (http://bugs.mysql.com/9778))

   * More tests in `Field.isOpaqueBinary()' to distinguish opaque
     binary (that is, fields with type `CHAR(n)' and `CHARACTER SET
     BINARY') from output of various scalar and aggregate functions
     that return strings.  (Bug#9778 (http://bugs.mysql.com/9778))

   * `DBMD.getTables()' shouldn't return tables if views are asked for,
     even if the database version doesn't support views.  (Bug#9778
     (http://bugs.mysql.com/9778))

   * Should accept `null' for name patterns in DBMD (meaning ``%''),
     even though it isn't JDBC compliant, for legacy's sake. Disable by
     setting connection property `nullNamePatternMatchesAll' to `false'
     (which will be the default value in C/J 3.2.x).  (Bug#9769
     (http://bugs.mysql.com/9769))

   * The performance metrics feature now gathers information about
     number of tables referenced in a SELECT.  (Bug#9704
     (http://bugs.mysql.com/9704))

   * The logging system is now automatically configured. If the value
     has been set by the user, via the URL property `logger' or the
     system property `com.mysql.jdbc.logger', then use that, otherwise,
     autodetect it using the following steps:

       1. Log4j, if it is available,

       2. Then JDK1.4 logging,

       3. Then fallback to our `STDERR' logging.

     (Bug#9704 (http://bugs.mysql.com/9704))

   * `Statement.getMoreResults()' could throw NPE when existing result
     set was `.close()'d.  (Bug#9704 (http://bugs.mysql.com/9704))

   * Stored procedures with *Note `DECIMAL': numeric-types.  parameters
     with storage specifications that contained ``,'' in them would
     fail.  (Bug#9682 (http://bugs.mysql.com/9682))

   * `PreparedStatement.setObject(int, Object, int type, int scale)'
     now uses scale value for `BigDecimal' instances.  (Bug#9682
     (http://bugs.mysql.com/9682))

   * Added support for the c3p0 connection pool's
     (`http://c3p0.sf.net/') validation/connection checker interface
     which uses the lightweight `COM_PING' call to the server if
     available. To use it, configure your c3p0 connection pool's
     `connectionTesterClassName' property to use
     `com.mysql.jdbc.integration.c3p0.MysqlConnectionTester'.
     (Bug#9320 (http://bugs.mysql.com/9320))

   * `PreparedStatement.getMetaData()' inserts blank row in database
     under certain conditions when not using server-side prepared
     statements.  (Bug#9320 (http://bugs.mysql.com/9320))

   * Better detection of `LIMIT' inside/outside of quoted strings so
     that the driver can more correctly determine whether a prepared
     statement can be prepared on the server or not.  (Bug#9320
     (http://bugs.mysql.com/9320))

   * `Connection.canHandleAsPreparedStatement()' now makes `best
     effort' to distinguish `LIMIT' clauses with placeholders in them
     from ones without in order to have fewer false positives when
     generating work-arounds for statements the server cannot currently
     handle as server-side prepared statements.  (Bug#9320
     (http://bugs.mysql.com/9320))

   * Fixed `build.xml' to not compile `log4j' logging if `log4j' not
     available.  (Bug#9320 (http://bugs.mysql.com/9320))

   * Added finalizers to `ResultSet' and `Statement' implementations to
     be JDBC spec-compliant, which requires that if not explicitly
     closed, these resources should be closed upon garbage collection.
     (Bug#9319 (http://bugs.mysql.com/9319))

   * Stored procedures with same name in different databases confuse
     the driver when it tries to determine parameter counts/types.
     (Bug#9319 (http://bugs.mysql.com/9319))

   * A continuation of Bug#8868 (http://bugs.mysql.com/8868), where
     functions used in queries that should return non-string types when
     resolved by temporary tables suddenly become opaque binary strings
     (work-around for server limitation). Also fixed fields with type of
     `CHAR(n) CHARACTER SET BINARY' to return correct/matching classes
     for `RSMD.getColumnClassName()' and `ResultSet.getObject()'.
     (Bug#9236 (http://bugs.mysql.com/9236))

   * Cannot use `UTF-8' for characterSetResults configuration property.
     (Bug#9206 (http://bugs.mysql.com/9206))

   * `PreparedStatement.addBatch()' doesn't work with server-side
     prepared statements and streaming *Note `BINARY':
     binary-varbinary. data.  (Bug#9040 (http://bugs.mysql.com/9040))

   * `ServerPreparedStatements' now correctly `stream' *Note `BLOB':
     blob./`CLOB' data to the server. You can configure the threshold
     chunk size using the JDBC URL property `blobSendChunkSize' (the
     default is 1MB).  (Bug#8868 (http://bugs.mysql.com/8868))

   * `DATE_FORMAT()' queries returned as *Note `BLOB': blob.s from
     `getObject()'.  (Bug#8868 (http://bugs.mysql.com/8868))

   * Server-side session variables can be preset at connection time by
     passing them as a comma-delimited list for the connection property
     `sessionVariables'.  (Bug#8868 (http://bugs.mysql.com/8868))

   * `BlobFromLocator' now uses correct identifier quoting when
     generating prepared statements.  (Bug#8868
     (http://bugs.mysql.com/8868))

   * Fixed regression in `ping()' for users using `autoReconnect=true'.
     (Bug#8868 (http://bugs.mysql.com/8868))

   * Check for empty strings (`''') when converting *Note `CHAR':
     char./*Note `VARCHAR': char.  column data to numbers, throw
     exception if `emptyStringsConvertToZero' configuration property is
     set to `false' (for backward-compatibility with 3.0, it is now set
     to `true' by default, but will most likely default to `false' in
     3.2).  (Bug#8803 (http://bugs.mysql.com/8803))

   * `DATA_TYPE' column from `DBMD.getBestRowIdentifier()' causes
     `ArrayIndexOutOfBoundsException' when accessed (and in fact,
     didn't return any value).  (Bug#8803 (http://bugs.mysql.com/8803))

   * `DBMD.supportsMixedCase*Identifiers()' returns wrong value on
     servers running on case-sensitive file systems.  (Bug#8800
     (http://bugs.mysql.com/8800))

   * `DBMD.supportsResultSetConcurrency()' not returning `true' for
     forward-only/read-only result sets (we obviously support this).
     (Bug#8792 (http://bugs.mysql.com/8792))

   * Fixed `ResultSet.getTime()' on a `NULL' value for server-side
     prepared statements throws NPE.

   * Made `Connection.ping()' a public method.

   * Added support for new precision-math *Note `DECIMAL':
     numeric-types. type in MySQL 5.0.3 and up.

   * Fixed `DatabaseMetaData.getTables()' returning views when they
     were not asked for as one of the requested table types.


File: manual.info,  Node: cj-news-3-1-7,  Next: cj-news-3-1-6,  Prev: cj-news-3-1-8,  Up: cg-news-3-1

C.7.3.9 Changes in MySQL Connector/J 3.1.7 (18 February 2005)
.............................................................

Bugs fixed:

   * `PreparedStatements' not creating streaming result sets.
     (Bug#8487 (http://bugs.mysql.com/8487))

   * Don't pass `NULL' to `String.valueOf()' in
     `ResultSet.getNativeConvertToString()', as it stringifies it (that
     is, returns `null'), which is not correct for the method in
     question.  (Bug#8487 (http://bugs.mysql.com/8487))

   * Fixed NPE in `ResultSet.realClose()' when using usage advisor and
     result set was already closed.  (Bug#8428
     (http://bugs.mysql.com/8428))

   * `ResultSet.getString()' doesn't maintain format stored on server,
     bug fix only enabled when `noDatetimeStringSync' property is set to
     `true' (the default is `false').  (Bug#8428
     (http://bugs.mysql.com/8428))

   * Added support for *Note `BIT': numeric-types. type in MySQL-5.0.3.
     The driver will treat `BIT(1-8)' as the JDBC standard *Note `BIT':
     numeric-types. type (which maps to `java.lang.Boolean'), as the
     server does not currently send enough information to determine the
     size of a bitfield when < 9 bits are declared.  `BIT(>9)' will be
     treated as *Note `VARBINARY': binary-varbinary, and will return
     `byte[]' when `getObject()' is called.  (Bug#8424
     (http://bugs.mysql.com/8424))

   * Added `useLocalSessionState' configuration property, when set to
     `true' the JDBC driver trusts that the application is well-behaved
     and only sets autocommit and transaction isolation levels using
     the methods provided on `java.sql.Connection', and therefore can
     manipulate these values in many cases without incurring
     round-trips to the database server.  (Bug#8424
     (http://bugs.mysql.com/8424))

   * Added `enableStreamingResults()' to `Statement' for connection
     pool implementations that check `Statement.setFetchSize()' for
     specification-compliant values. Call `Statement.setFetchSize(>=0)'
     to disable the streaming results for that statement.  (Bug#8424
     (http://bugs.mysql.com/8424))

   * `ResultSet.getBigDecimal()' throws exception when rounding would
     need to occur to set scale. The driver now chooses a rounding mode
     of `half up' if non-rounding `BigDecimal.setScale()' fails.
     (Bug#8424 (http://bugs.mysql.com/8424))

   * Fixed synchronization issue with
     `ServerPreparedStatement.serverPrepare()' that could cause
     deadlocks/crashes if connection was shared between threads.
     (Bug#8096 (http://bugs.mysql.com/8096))

   * Emulated locators corrupt binary data when using server-side
     prepared statements.  (Bug#8096 (http://bugs.mysql.com/8096))

   * Infinite recursion when `falling back' to master in failover
     configuration.  (Bug#7952 (http://bugs.mysql.com/7952))

   * Disable multi-statements (if enabled) for MySQL-4.1 versions prior
     to version 4.1.10 if the query cache is enabled, as the server
     returns wrong results in this configuration.  (Bug#7952
     (http://bugs.mysql.com/7952))

   * Removed `dontUnpackBinaryResults' functionality, the driver now
     always stores results from server-side prepared statements as is
     from the server and unpacks them on demand.  (Bug#7952
     (http://bugs.mysql.com/7952))

   * Fixed duplicated code in `configureClientCharset()' that prevented
     `useOldUTF8Behavior=true' from working properly.  (Bug#7952
     (http://bugs.mysql.com/7952))

   * Added `holdResultsOpenOverStatementClose' property (default is
     `false'), that keeps result sets open over statement.close() or
     new execution on same statement (suggested by Kevin Burton).
     (Bug#7715 (http://bugs.mysql.com/7715))

   * Detect new `sql_mode' variable in string form (it used to be
     integer) and adjust quoting method for strings appropriately.
     (Bug#7715 (http://bugs.mysql.com/7715))

   * Timestamps converted incorrectly to strings with server-side
     prepared statements and updatable result sets.  (Bug#7715
     (http://bugs.mysql.com/7715))

   * Timestamp key column data needed `_binary' stripped for
     `UpdatableResultSet.refreshRow()'.  (Bug#7686
     (http://bugs.mysql.com/7686))

   * Choose correct `direction' to apply time adjustments when both
     client and server are in GMT time zone when using
     `ResultSet.get(..., cal)' and `PreparedStatement.set(...., cal)'.
     (Bug#4718 (http://bugs.mysql.com/4718))

   * Remove `_binary' introducer from parameters used as in/out
     parameters in `CallableStatement'.  (Bug#4718
     (http://bugs.mysql.com/4718))

   * Always return `byte[]'s for output parameters registered as
     `*BINARY'.  (Bug#4718 (http://bugs.mysql.com/4718))

   * By default, the driver now scans SQL you are preparing via all
     variants of `Connection.prepareStatement()' to determine if it is
     a supported type of statement to prepare on the server side, and
     if it is not supported by the server, it instead prepares it as a
     client-side emulated prepared statement. You can disable this by
     passing `emulateUnsupportedPstmts=false' in your JDBC URL.
     (Bug#4718 (http://bugs.mysql.com/4718))

   * Added `dontTrackOpenResources' option (default is `false', to be
     JDBC compliant), which helps with memory use for non-well-behaved
     apps (that is, applications that don't close `Statement' objects
     when they should).  (Bug#4718 (http://bugs.mysql.com/4718))

   * Send correct value for `boolean' `true' to server for
     `PreparedStatement.setObject(n, "true", Types.BIT)'.  (Bug#4718
     (http://bugs.mysql.com/4718))

   * Fixed bug with Connection not caching statements from
     `prepareStatement()' when the statement wasn't a server-side
     prepared statement.  (Bug#4718 (http://bugs.mysql.com/4718))


File: manual.info,  Node: cj-news-3-1-6,  Next: cj-news-3-1-5,  Prev: cj-news-3-1-7,  Up: cg-news-3-1

C.7.3.10 Changes in MySQL Connector/J 3.1.6 (23 December 2004)
..............................................................

Bugs fixed:

   * `DBMD.getProcedures()' doesn't respect catalog parameter.
     (Bug#7026 (http://bugs.mysql.com/7026))

   * Fixed hang on `SocketInputStream.read()' with
     `Statement.setMaxRows()' and multiple result sets when driver has
     to truncate result set directly, rather than tacking a `LIMIT N'
     on the end of it.


File: manual.info,  Node: cj-news-3-1-5,  Next: cj-news-3-1-4,  Prev: cj-news-3-1-6,  Up: cg-news-3-1

C.7.3.11 Changes in MySQL Connector/J 3.1.5 (02 December 2004)
..............................................................

Bugs fixed:

   * Use 1MB packet for sending file for *Note `LOAD DATA LOCAL
     INFILE': load-data. if that is < `max_allowed_packet' on server.
     (Bug#6537 (http://bugs.mysql.com/6537))

   * `SUM()' on *Note `DECIMAL': numeric-types. with server-side
     prepared statement ignores scale if zero-padding is needed (this
     ends up being due to conversion to *Note `DOUBLE': numeric-types.
     by server, which when converted to a string to parse into
     `BigDecimal', loses all `padding' zeros).  (Bug#6537
     (http://bugs.mysql.com/6537))

   * Use `DatabaseMetaData.getIdentifierQuoteString()' when building
     DBMD queries.  (Bug#6537 (http://bugs.mysql.com/6537))

   * Use our own implementation of buffered input streams to get around
     blocking behavior of `java.io.BufferedInputStream'. Disable this
     with `useReadAheadInput=false'.  (Bug#6399
     (http://bugs.mysql.com/6399))

   * Make auto-deserialization of `java.lang.Objects' stored in *Note
     `BLOB': blob. columns configurable via `autoDeserialize' property
     (defaults to `false').  (Bug#6399 (http://bugs.mysql.com/6399))

   * `ResultSetMetaData.getColumnDisplaySize()' returns incorrect
     values for multi-byte charsets.  (Bug#6399
     (http://bugs.mysql.com/6399))

   * Re-work `Field.isOpaqueBinary()' to detect `CHAR(N) CHARACTER SET
     BINARY' to support fixed-length binary fields for
     `ResultSet.getObject()'.  (Bug#6399 (http://bugs.mysql.com/6399))

   * Failing to connect to the server when one of the addresses for the
     given host name is IPV6 (which the server does not yet bind on).
     The driver now loops through _all_ IP addresses for a given host,
     and stops on the first one that `accepts()' a `socket.connect()'.
     (Bug#6348 (http://bugs.mysql.com/6348))

   * Removed unwanted new `Throwable()' in `ResultSet' constructor due
     to bad merge (caused a new object instance that was never used for
     every result set created). Found while profiling for Bug#6359
     (http://bugs.mysql.com/6359).  (Bug#6225
     (http://bugs.mysql.com/6225))

   * `ServerSidePreparedStatement' allocating short-lived objects
     unnecessarily.  (Bug#6225 (http://bugs.mysql.com/6225))

   * Use null-safe-equals for key comparisons in updatable result sets.
     (Bug#6225 (http://bugs.mysql.com/6225))

   * Fixed too-early creation of `StringBuffer' in
     `EscapeProcessor.escapeSQL()', also return `String' when escaping
     not needed (to avoid unnecessary object allocations). Found while
     profiling for Bug#6359 (http://bugs.mysql.com/6359).  (Bug#6225
     (http://bugs.mysql.com/6225))

   * `UNSIGNED BIGINT' unpacked incorrectly from server-side prepared
     statement result sets.  (Bug#5729 (http://bugs.mysql.com/5729))

   * Added experimental configuration property
     `dontUnpackBinaryResults', which delays unpacking binary result
     set values until they're asked for, and only creates object
     instances for non-numerical values (it is set to `false' by
     default). For some usecase/jvm combinations, this is friendlier on
     the garbage collector.  (Bug#5706 (http://bugs.mysql.com/5706))

   * Don't throw exceptions for `Connection.releaseSavepoint()'.
     (Bug#5706 (http://bugs.mysql.com/5706))

   * Inefficient detection of pre-existing string instances in
     `ResultSet.getNativeString()'.  (Bug#5706
     (http://bugs.mysql.com/5706))

   * Use a per-session `Calendar' instance by default when decoding
     dates from `ServerPreparedStatements' (set to old, less performant
     behavior by setting property `dynamicCalendars=true').  (Bug#5706
     (http://bugs.mysql.com/5706))

   * Fixed batched updates with server prepared statements weren't
     looking if the types had changed for a given batched set of
     parameters compared to the previous set, causing the server to
     return the error `Wrong arguments to mysql_stmt_execute()'.
     (Bug#5235 (http://bugs.mysql.com/5235))

   * Handle case when string representation of timestamp contains
     trailing ``.'' with no numbers following it.  (Bug#5235
     (http://bugs.mysql.com/5235))

   * Server-side prepared statements did not honor
     `zeroDateTimeBehavior' property, and would cause class-cast
     exceptions when using `ResultSet.getObject()', as the all-zero
     string was always returned.  (Bug#5235
     (http://bugs.mysql.com/5235))

   * Fix comparisons made between string constants and dynamic strings
     that are converted with either `toUpperCase()' or `toLowerCase()'
     to use `Locale.ENGLISH', as some locales `override' case rules for
     English. Also use `StringUtils.indexOfIgnoreCase()' instead of
     `.toUpperCase().indexOf()', avoids creating a very short-lived
     transient `String' instance.


File: manual.info,  Node: cj-news-3-1-4,  Next: cj-news-3-1-3,  Prev: cj-news-3-1-5,  Up: cg-news-3-1

C.7.3.12 Changes in MySQL Connector/J 3.1.4 (04 September 2004)
...............................................................

Bugs fixed:

   * Fixed `ServerPreparedStatement' to read prepared statement
     metadata off the wire, even though it is currently a placeholder
     instead of using `MysqlIO.clearInputStream()' which didn't work at
     various times because data wasn't available to read from the
     server yet. This fixes sporadic errors users were having with
     `ServerPreparedStatements' throwing
     `ArrayIndexOutOfBoundExceptions'.  (Bug#5032
     (http://bugs.mysql.com/5032))

   * Added three ways to deal with all-zero datetimes when reading them
     from a `ResultSet': `exception' (the default), which throws an
     `SQLException' with an SQLState of `S1009'; `convertToNull', which
     returns `NULL' instead of the date; and `round', which rounds the
     date to the nearest closest value which is `'0001-01-01''.
     (Bug#5032 (http://bugs.mysql.com/5032))

   * The driver is more strict about truncation of numerics on
     `ResultSet.get*()', and will throw an `SQLException' when
     truncation is detected. You can disable this by setting
     `jdbcCompliantTruncation' to `false' (it is enabled by default, as
     this functionality is required for JDBC compliance).  (Bug#5032
     (http://bugs.mysql.com/5032))

   * You can now use URLs in *Note `LOAD DATA LOCAL INFILE': load-data.
     statements, and the driver will use Java's built-in handlers for
     retreiving the data and sending it to the server. This feature is
     not enabled by default, you must set the `allowUrlInLocalInfile'
     connection property to `true'.  (Bug#5032
     (http://bugs.mysql.com/5032))

   * `ResultSet.getObject()' doesn't return type `Boolean' for
     pseudo-bit types from prepared statements on 4.1.x (shortcut for
     avoiding extra type conversion when using binary-encoded result
     sets obscured test in `getObject()' for `pseudo' bit type).
     (Bug#5032 (http://bugs.mysql.com/5032))

   * Use `com.mysql.jdbc.Message''s classloader when loading resource
     bundle, should fix sporadic issues when the caller's classloader
     can't locate the resource bundle.  (Bug#5032
     (http://bugs.mysql.com/5032))

   * `ServerPreparedStatements' dealing with return of *Note `DECIMAL':
     numeric-types. type don't work.  (Bug#5012
     (http://bugs.mysql.com/5012))

   * Track packet sequence numbers if `enablePacketDebug=true', and
     throw an exception if packets received out-of-order.  (Bug#4689
     (http://bugs.mysql.com/4689))

   * `ResultSet.wasNull()' does not work for primatives if a previous
     `null' was returned.  (Bug#4689 (http://bugs.mysql.com/4689))

   * Optimized integer number parsing, enable `old' slower integer
     parsing using JDK classes via `useFastIntParsing=false' property.
     (Bug#4642 (http://bugs.mysql.com/4642))

   * Added `useOnlyServerErrorMessages' property, which causes message
     text in exceptions generated by the server to only contain the
     text sent by the server (as opposed to the SQLState's `standard'
     description, followed by the server's error message). This
     property is set to `true' by default.  (Bug#4642
     (http://bugs.mysql.com/4642))

   * `ServerPreparedStatement.execute*()' sometimes threw
     `ArrayIndexOutOfBoundsException' when unpacking field metadata.
     (Bug#4642 (http://bugs.mysql.com/4642))

   * Connector/J 3.1.3 beta does not handle integers correctly (caused
     by changes to support unsigned reads in `Buffer.readInt()' ->
     `Buffer.readShort()').  (Bug#4510 (http://bugs.mysql.com/4510))

   * Added support in `DatabaseMetaData.getTables()' and
     `getTableTypes()' for views, which are now available in MySQL
     server 5.0.x.  (Bug#4510 (http://bugs.mysql.com/4510))

   * `ResultSet.getObject()' returns wrong type for strings when using
     prepared statements.  (Bug#4482 (http://bugs.mysql.com/4482))

   * Calling `MysqlPooledConnection.close()' twice (even though an
     application error), caused NPE. Fixed.  (Bug#4482
     (http://bugs.mysql.com/4482))


File: manual.info,  Node: cj-news-3-1-3,  Next: cj-news-3-1-2,  Prev: cj-news-3-1-4,  Up: cg-news-3-1

C.7.3.13 Changes in MySQL Connector/J 3.1.3 (07 July 2004)
..........................................................

Bugs fixed:

   * Support new time zone variables in MySQL-4.1.3 when
     `useTimezone=true'.  (Bug#4311 (http://bugs.mysql.com/4311))

   * Error in retrieval of `mediumint' column with prepared statements
     and binary protocol.  (Bug#4311 (http://bugs.mysql.com/4311))

   * Support for unsigned numerics as return types from prepared
     statements. This also causes a change in `ResultSet.getObject()'
     for the `bigint unsigned' type, which used to return `BigDecimal'
     instances, it now returns instances of `java.lang.BigInteger'.
     (Bug#4311 (http://bugs.mysql.com/4311))

   * Externalized more messages (on-going effort).  (Bug#4119
     (http://bugs.mysql.com/4119))

   * Null bitmask sent for server-side prepared statements was
     incorrect.  (Bug#4119 (http://bugs.mysql.com/4119))

   * Added constants for MySQL error numbers (publicly accessible, see
     `com.mysql.jdbc.MysqlErrorNumbers'), and the ability to generate
     the mappings of vendor error codes to SQLStates that the driver
     uses (for documentation purposes).  (Bug#4119
     (http://bugs.mysql.com/4119))

   * Added packet debuging code (see the `enablePacketDebug' property
     documentation).  (Bug#4119 (http://bugs.mysql.com/4119))

   * Use SQL Standard SQL states by default, unless `useSqlStateCodes'
     property is set to `false'.  (Bug#4119
     (http://bugs.mysql.com/4119))

   * Mangle output parameter names for `CallableStatements' so they
     will not clash with user variable names.

   * Added support for `INOUT' parameters in `CallableStatements'.


File: manual.info,  Node: cj-news-3-1-2,  Next: cj-news-3-1-1,  Prev: cj-news-3-1-3,  Up: cg-news-3-1

C.7.3.14 Changes in MySQL Connector/J 3.1.2 (09 June 2004)
..........................................................

Bugs fixed:

   * Don't enable server-side prepared statements for server version
     5.0.0 or 5.0.1, as they aren't compatible with the '4.1.2+' style
     that the driver uses (the driver expects information to come back
     that isn't there, so it hangs).  (Bug#3804
     (http://bugs.mysql.com/3804))

   * `getWarnings()' returns `SQLWarning' instead of `DataTruncation'.
     (Bug#3804 (http://bugs.mysql.com/3804))

   * `getProcedureColumns()' doesn't work with wildcards for procedure
     name.  (Bug#3540 (http://bugs.mysql.com/3540))

   * `getProcedures()' does not return any procedures in result set.
     (Bug#3539 (http://bugs.mysql.com/3539))

   * Fixed `DatabaseMetaData.getProcedures()' when run on MySQL-5.0.0
     (output of *Note `SHOW PROCEDURE STATUS': show-procedure-status.
     changed between 5.0.0 and 5.0.1.  (Bug#3520
     (http://bugs.mysql.com/3520))

   * Added `connectionCollation' property to cause driver to issue `set
     collation_connection=...' query on connection init if default
     collation for given charset is not appropriate.  (Bug#3520
     (http://bugs.mysql.com/3520))

   * `DBMD.getSQLStateType()' returns incorrect value.  (Bug#3520
     (http://bugs.mysql.com/3520))

   * Correctly map output parameters to position given in
     `prepareCall()' versus. order implied during
     `registerOutParameter()'.  (Bug#3146 (http://bugs.mysql.com/3146))

   * Cleaned up detection of server properties.  (Bug#3146
     (http://bugs.mysql.com/3146))

   * Correctly detect initial character set for servers >= 4.1.0.
     (Bug#3146 (http://bugs.mysql.com/3146))

   * Support placeholder for parameter metadata for server >= 4.1.2.
     (Bug#3146 (http://bugs.mysql.com/3146))

   * Added `gatherPerformanceMetrics' property, along with properties
     to control when/where this info gets logged (see docs for more
     info).

   * Fixed case when no parameters could cause a `NullPointerException'
     in `CallableStatement.setOutputParameters()'.

   * Enabled callable statement caching via `cacheCallableStmts'
     property.

   * Fixed sending of split packets for large queries, enabled nio
     ability to send large packets as well.

   * Added `.toString()' functionality to `ServerPreparedStatement',
     which should help if you're trying to debug a query that is a
     prepared statement (it shows SQL as the server would process).

   * Added `logSlowQueries' property, along with
     `slowQueriesThresholdMillis' property to control when a query
     should be considered `slow.'

   * Removed wrapping of exceptions in `MysqlIO.changeUser()'.

   * Fixed stored procedure parameter parsing info when size was
     specified for a parameter (for example, `char()', `varchar()').

   * `ServerPreparedStatements' weren't actually de-allocating
     server-side resources when `.close()' was called.

   * Fixed case when no output parameters specified for a stored
     procedure caused a bogus query to be issued to retrieve out
     parameters, leading to a syntax error from the server.


File: manual.info,  Node: cj-news-3-1-1,  Next: cj-news-3-1-0,  Prev: cj-news-3-1-2,  Up: cg-news-3-1

C.7.3.15 Changes in MySQL Connector/J 3.1.1 (14 February 2004 alpha)
....................................................................

Bugs fixed:

   * Use DocBook version of docs for shipped versions of drivers.
     (Bug#2671 (http://bugs.mysql.com/2671))

   * `NULL' fields were not being encoded correctly in all cases in
     server-side prepared statements.  (Bug#2671
     (http://bugs.mysql.com/2671))

   * Fixed rare buffer underflow when writing numbers into buffers for
     sending prepared statement execution requests.  (Bug#2671
     (http://bugs.mysql.com/2671))

   * Fixed `ConnectionProperties' that weren't properly exposed via
     accessors, cleaned up `ConnectionProperties' code.  (Bug#2623
     (http://bugs.mysql.com/2623))

   * Class-cast exception when using scrolling result sets and
     server-side prepared statements.  (Bug#2623
     (http://bugs.mysql.com/2623))

   * Merged unbuffered input code from 3.0.  (Bug#2623
     (http://bugs.mysql.com/2623))

   * Enabled streaming of result sets from server-side prepared
     statements.  (Bug#2606 (http://bugs.mysql.com/2606))

   * Server-side prepared statements were not returning datatype *Note
     `YEAR': year. correctly.  (Bug#2606 (http://bugs.mysql.com/2606))

   * Fixed charset conversion issue in `getTables()'.  (Bug#2502
     (http://bugs.mysql.com/2502))

   * Implemented multiple result sets returned from a statement or
     stored procedure.  (Bug#2502 (http://bugs.mysql.com/2502))

   * Implemented `Connection.prepareCall()', and `DatabaseMetaData'.
     `getProcedures()' and `getProcedureColumns()'.  (Bug#2359
     (http://bugs.mysql.com/2359))

   * Merged prepared statement caching, and `.getMetaData()' support
     from 3.0 branch.  (Bug#2359 (http://bugs.mysql.com/2359))

   * Fixed off-by-1900 error in some cases for years in
     `TimeUtil.fastDate'/`TimeCreate()' when unpacking results from
     server-side prepared statements.  (Bug#2359
     (http://bugs.mysql.com/2359))

   * Reset `long binary' parameters in `ServerPreparedStatement' when
     `clearParameters()' is called, by sending `COM_RESET_STMT' to the
     server.  (Bug#2359 (http://bugs.mysql.com/2359))

   * `NULL' values for numeric types in binary encoded result sets
     causing `NullPointerExceptions'.  (Bug#2359
     (http://bugs.mysql.com/2359))

   * Display where/why a connection was implicitly closed (to aid
     debugging).  (Bug#1673 (http://bugs.mysql.com/1673))

   * `DatabaseMetaData.getColumns()' is not returning correct column
     ordinal info for non-`'%'' column name patterns.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * Fixed `NullPointerException' in
     `ServerPreparedStatement.setTimestamp()', as well as year and
     month descrepencies in `ServerPreparedStatement.setTimestamp()',
     `setDate()'.  (Bug#1673 (http://bugs.mysql.com/1673))

   * Added ability to have multiple database/JVM targets for compliance
     and regression/unit tests in `build.xml'.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * Fixed sending of queries larger than 16M.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * Merged fix of datatype mapping from MySQL type *Note `FLOAT':
     numeric-types. to `java.sql.Types.REAL' from 3.0 branch.
     (Bug#1673 (http://bugs.mysql.com/1673))

   * Fixed NPE and year/month bad conversions when accessing some
     datetime functionality in `ServerPreparedStatements' and their
     resultant result sets.  (Bug#1673 (http://bugs.mysql.com/1673))

   * Added named and indexed input/output parameter support to
     `CallableStatement'. MySQL-5.0.x or newer.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * `CommunicationsException' implemented, that tries to determine why
     communications was lost with a server, and displays possible
     reasons when `.getMessage()' is called.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * Detect collation of column for `RSMD.isCaseSensitive()'.
     (Bug#1673 (http://bugs.mysql.com/1673))

   * Optimized `Buffer.readLenByteArray()' to return shared empty byte
     array when length is 0.

   * Fix support for table aliases when checking for all primary keys
     in `UpdatableResultSet'.

   * Unpack `unknown' data types from server prepared statements as
     `Strings'.

   * Implemented `Statement.getWarnings()' for MySQL-4.1 and newer
     (using *Note `SHOW WARNINGS': show-warnings.).

   * Ensure that warnings are cleared before executing queries on
     prepared statements, as-per JDBC spec (now that we support
     warnings).

   * Correctly initialize datasource properties from JNDI Refs,
     including explicitly specified URLs.

   * Implemented long data (Blobs, Clobs, InputStreams, Readers) for
     server prepared statements.

   * Deal with 0-length tokens in `EscapeProcessor' (caused by callable
     statement escape syntax).

   * `DatabaseMetaData' now reports `supportsStoredProcedures()' for
     MySQL versions >= 5.0.0

   * Support for *Note `mysql_change_user()': mysql-change-user.  See
     the `changeUser()' method in `com.mysql.jdbc.Connection'.

   * Removed `useFastDates' connection property.

   * Support for NIO. Use `useNIO=true' on platforms that support NIO.

   * Check for closed connection on delete/update/insert row operations
     in `UpdatableResultSet'.

   * Support for transaction savepoints (MySQL >= 4.0.14 or 4.1.1).

   * Support `old' `profileSql' capitalization in
     `ConnectionProperties'. This property is deprecated, you should use
     `profileSQL' if possible.

   * Fixed character encoding issues when converting bytes to ASCII
     when MySQL doesn't provide the character set, and the JVM is set
     to a multi-byte encoding (usually affecting retrieval of numeric
     values).

   * Centralized setting of result set type and concurrency.

   * Fixed bug with `UpdatableResultSets' not using client-side
     prepared statements.

   * Default result set type changed to `TYPE_FORWARD_ONLY' (JDBC
     compliance).

   * Fixed `IllegalAccessError' to `Calendar.getTimeInMillis()' in
     `DateTimeValue' (for JDK < 1.4).

   * Allow contents of `PreparedStatement.setBlob()' to be retained
     between calls to `.execute*()'.

   * Fixed stack overflow in `Connection.prepareCall()' (bad merge).

   * Refactored how connection properties are set and exposed as
     `DriverPropertyInfo' as well as `Connection' and `DataSource'
     properties.

   * Reduced number of methods called in average query to be more
     efficient.

   * Prepared `Statements' will be re-prepared on auto-reconnect. Any
     errors encountered are postponed until first attempt to re-execute
     the re-prepared statement.


File: manual.info,  Node: cj-news-3-1-0,  Prev: cj-news-3-1-1,  Up: cg-news-3-1

C.7.3.16 Changes in MySQL Connector/J 3.1.0 (18 February 2003 alpha)
....................................................................

Bugs fixed:

   * Added `useServerPrepStmts' property (default `false'). The driver
     will use server-side prepared statements when the server version
     supports them (4.1 and newer) when this property is set to `true'.
     It is currently set to `false' by default until all bind/fetch
     functionality has been implemented. Currently only DML prepared
     statements are implemented for 4.1 server-side prepared statements.

   * Added `requireSSL' property.

   * Track open `Statements', close all when `Connection.close()' is
     called (JDBC compliance).


File: manual.info,  Node: cg-news-3-0,  Next: cj-news-2-0,  Prev: cg-news-3-1,  Up: cj-news

C.7.4 Changes in MySQL Connector/J 3.0.x
----------------------------------------

* Menu:

* cj-news-3-0-17::               Changes in MySQL Connector/J 3.0.17 (23 June 2005)
* cj-news-3-0-16::               Changes in MySQL Connector/J 3.0.16 (15 November 2004)
* cj-news-3-0-15::               Changes in MySQL Connector/J 3.0.15 (04 September 2004)
* cj-news-3-0-14::               Changes in MySQL Connector/J 3.0.14 (28 May 2004)
* cj-news-3-0-13::               Changes in MySQL Connector/J 3.0.13 (27 May 2004)
* cj-news-3-0-12::               Changes in MySQL Connector/J 3.0.12 (18 May 2004)
* cj-news-3-0-11::               Changes in MySQL Connector/J 3.0.11 (19 February 2004)
* cj-news-3-0-10::               Changes in MySQL Connector/J 3.0.10 (13 January 2004)
* cj-news-3-0-9::                Changes in MySQL Connector/J 3.0.9 (07 October 2003)
* cj-news-3-0-8::                Changes in MySQL Connector/J 3.0.8 (23 May 2003)
* cj-news-3-0-7::                Changes in MySQL Connector/J 3.0.7 (08 April 2003)
* cj-news-3-0-6::                Changes in MySQL Connector/J 3.0.6 (18 February 2003)
* cj-news-3-0-5::                Changes in MySQL Connector/J 3.0.5 (22 January 2003)
* cj-news-3-0-4::                Changes in MySQL Connector/J 3.0.4 (06 January 2003)
* cj-news-3-0-3::                Changes in MySQL Connector/J 3.0.3 (17 December 2002)
* cj-news-3-0-2::                Changes in MySQL Connector/J 3.0.2 (08 November 2002)
* cj-news-3-0-1::                Changes in MySQL Connector/J 3.0.1 (21 September 2002)
* cj-news-3-0-0::                Changes in MySQL Connector/J 3.0.0 (31 July 2002)


File: manual.info,  Node: cj-news-3-0-17,  Next: cj-news-3-0-16,  Prev: cg-news-3-0,  Up: cg-news-3-0

C.7.4.1 Changes in MySQL Connector/J 3.0.17 (23 June 2005)
..........................................................

Bugs fixed:

   * Workaround for server Bug#9098 (http://bugs.mysql.com/9098):
     Default values of `CURRENT_*' for *Note `DATE': datetime, *Note
     `TIME': time, *Note `DATETIME': datetime, and *Note `TIMESTAMP':
     datetime. columns can't be distinguished from `string' values, so
     `UpdatableResultSet.moveToInsertRow()' generates bad SQL for
     inserting default values.  (Bug#8812 (http://bugs.mysql.com/8812))

   * `NON_UNIQUE' column from `DBMD.getIndexInfo()' returned inverted
     value.  (Bug#8812 (http://bugs.mysql.com/8812))

   * `EUCKR' charset is sent as `SET NAMES euc_kr' which MySQL-4.1 and
     newer doesn't understand.  (Bug#8629 (http://bugs.mysql.com/8629))

   * Added support for the `EUC_JP_Solaris' character encoding, which
     maps to a MySQL encoding of `eucjpms' (backported from 3.1
     branch). This only works on servers that support `eucjpms', namely
     5.0.3 or later.  (Bug#8629 (http://bugs.mysql.com/8629))

   * Use hex escapes for `PreparedStatement.setBytes()' for double-byte
     charsets including `aliases' `Windows-31J', `CP934', `MS932'.
     (Bug#8629 (http://bugs.mysql.com/8629))

   * `DatabaseMetaData.supportsSelectForUpdate()' returns correct value
     based on server version.  (Bug#8629 (http://bugs.mysql.com/8629))

   * Which requires hex escaping of binary data when using multi-byte
     charsets with prepared statements.  (Bug#8064
     (http://bugs.mysql.com/8064))

   * Fixed duplicated code in `configureClientCharset()' that prevented
     `useOldUTF8Behavior=true' from working properly.  (Bug#7952
     (http://bugs.mysql.com/7952))

   * Backported SQLState codes mapping from Connector/J 3.1, enable
     with `useSqlStateCodes=true' as a connection property, it defaults
     to `false' in this release, so that we don't break legacy
     applications (it defaults to `true' starting with Connector/J 3.1).
     (Bug#7686 (http://bugs.mysql.com/7686))

   * Timestamp key column data needed `_binary' stripped for
     `UpdatableResultSet.refreshRow()'.  (Bug#7686
     (http://bugs.mysql.com/7686))

   * `MS932', `SHIFT_JIS', and `Windows_31J' not recognized as aliases
     for `sjis'.  (Bug#7607 (http://bugs.mysql.com/7607))

   * Handle streaming result sets with more than 2 billion rows
     properly by fixing wraparound of row number counter.  (Bug#7601
     (http://bugs.mysql.com/7601))

   * `PreparedStatement.fixDecimalExponent()' adding extra `+', making
     number unparseable by MySQL server.  (Bug#7601
     (http://bugs.mysql.com/7601))

   * Escape sequence {fn convert(..., type)} now supports ODBC-style
     types that are prepended by `SQL_'.  (Bug#7601
     (http://bugs.mysql.com/7601))

   * Statements created from a pooled connection were returning
     physical connection instead of logical connection when
     `getConnection()' was called.  (Bug#7316
     (http://bugs.mysql.com/7316))

   * Support new protocol type `MYSQL_TYPE_VARCHAR'.  (Bug#7081
     (http://bugs.mysql.com/7081))

   * Added `useOldUTF8Behavior'' configuration property, which causes
     JDBC driver to act like it did with MySQL-4.0.x and earlier when
     the character encoding is `utf-8' when connected to MySQL-4.1 or
     newer.  (Bug#7081 (http://bugs.mysql.com/7081))

   * `DatabaseMetaData.getIndexInfo()' ignored `unique' parameter.
     (Bug#7081 (http://bugs.mysql.com/7081))

   * `PreparedStatement.fixDecimalExponent()' adding extra `+', making
     number unparseable by MySQL server.  (Bug#7061
     (http://bugs.mysql.com/7061))

   * `PreparedStatements' don't encode Big5 (and other multi-byte)
     character sets correctly in static SQL strings.  (Bug#7033
     (http://bugs.mysql.com/7033))

   * Connections starting up failed-over (due to down master) never
     retry master.  (Bug#6966 (http://bugs.mysql.com/6966))

   * Adding `CP943' to aliases for `sjis'.  (Bug#6549
     (http://bugs.mysql.com/6549), Bug#7607
     (http://bugs.mysql.com/7607))

   * `Timestamp'/`Time' conversion goes in the wrong `direction' when
     `useTimeZone=true' and server time zone differs from client time
     zone.  (Bug#5874 (http://bugs.mysql.com/5874))


File: manual.info,  Node: cj-news-3-0-16,  Next: cj-news-3-0-15,  Prev: cj-news-3-0-17,  Up: cg-news-3-0

C.7.4.2 Changes in MySQL Connector/J 3.0.16 (15 November 2004)
..............................................................

Bugs fixed:

   * Made `TINYINT(1)' -> *Note `BIT': numeric-types./`Boolean'
     conversion configurable via `tinyInt1isBit' property (default
     `true' to be JDBC compliant out of the box).  (Bug#5664
     (http://bugs.mysql.com/5664))

   * Off-by-one bug in `Buffer.readString(STRING)'.  (Bug#5664
     (http://bugs.mysql.com/5664))

   * `ResultSet.updateByte()' when on insert row throws
     `ArrayOutOfBoundsException'.  (Bug#5664
     (http://bugs.mysql.com/5664))

   * Fixed regression where `useUnbufferedInput' was defaulting to
     `false'.  (Bug#5664 (http://bugs.mysql.com/5664))

   * `ResultSet.getTimestamp()' on a column with *Note `TIME': time. in
     it fails.  (Bug#5664 (http://bugs.mysql.com/5664))

   * Fixed `DatabaseMetaData.getTypes()' returning incorrect (this is,
     non-negative) scale for the *Note `NUMERIC': numeric-types. type.
     (Bug#5664 (http://bugs.mysql.com/5664))

   * Only set `character_set_results' during connection establishment
     if server version >= 4.1.1.  (Bug#5664
     (http://bugs.mysql.com/5664))

   * Fixed `ResultSetMetaData.isReadOnly()' to detect non-writable
     columns when connected to MySQL-4.1 or newer, based on existence
     of `original' table and column names.

   * Re-issue character set configuration commands when re-using pooled
     connections and/or `Connection.changeUser()' when connected to
     MySQL-4.1 or newer.


File: manual.info,  Node: cj-news-3-0-15,  Next: cj-news-3-0-14,  Prev: cj-news-3-0-16,  Up: cg-news-3-0

C.7.4.3 Changes in MySQL Connector/J 3.0.15 (04 September 2004)
...............................................................

Bugs fixed:

   * `ResultSet.getMetaData()' should not return incorrectly
     initialized metadata if the result set has been closed, but should
     instead throw an `SQLException'. Also fixed for `getRow()' and
     `getWarnings()' and traversal methods by calling `checkClosed()'
     before operating on instance-level fields that are nullified during
     `.close()'.  (Bug#5069 (http://bugs.mysql.com/5069))

   * Use `_binary' introducer for `PreparedStatement.setBytes()' and
     `set*Stream()' when connected to MySQL-4.1.x or newer to avoid
     misinterpretation during character conversion.  (Bug#5069
     (http://bugs.mysql.com/5069))

   * Parse new time zone variables from 4.1.x servers.  (Bug#5069
     (http://bugs.mysql.com/5069))

   * `ResultSet' should release `Field[]' instance in `.close()'.
     (Bug#5022 (http://bugs.mysql.com/5022))

   * `RSMD.getPrecision()' returning 0 for non-numeric types (should
     return max length in chars for non-binary types, max length in
     bytes for binary types). This fix also fixes mapping of
     `RSMD.getColumnType()' and `RSMD.getColumnTypeName()' for the
     *Note `BLOB': blob. types based on the length sent from the server
     (the server doesn't distinguish between *Note `TINYBLOB': blob,
     *Note `BLOB': blob, *Note `MEDIUMBLOB': blob. or *Note `LONGBLOB':
     blob. at the network protocol level).  (Bug#4880
     (http://bugs.mysql.com/4880))

   * `Production' is now `GA' (General Availability) in naming scheme
     of distributions.  (Bug#4860 (http://bugs.mysql.com/4860),
     Bug#4138 (http://bugs.mysql.com/4138))

   * `DBMD.getColumns()' returns incorrect JDBC type for unsigned
     columns. This affects type mappings for all numeric types in the
     `RSMD.getColumnType()' and `RSMD.getColumnTypeNames()' methods as
     well, to ensure that `like' types from `DBMD.getColumns()' match
     up with what `RSMD.getColumnType()' and `getColumnTypeNames()'
     return.  (Bug#4860 (http://bugs.mysql.com/4860), Bug#4138
     (http://bugs.mysql.com/4138))

   * Calling `.close()' twice on a `PooledConnection' causes NPE.
     (Bug#4808 (http://bugs.mysql.com/4808))

   * *Note `DOUBLE': numeric-types. mapped twice in
     `DBMD.getTypeInfo()'.  (Bug#4742 (http://bugs.mysql.com/4742))

   * Added FLOSS license exemption.  (Bug#4742
     (http://bugs.mysql.com/4742))

   * Removed redundant calls to `checkRowPos()' in `ResultSet'.
     (Bug#4334 (http://bugs.mysql.com/4334))

   * Failover for `autoReconnect' not using port numbers for any hosts,
     and not retrying all hosts.

     *Warning*:

     This required a change to the `SocketFactory' `connect()' method
     signature, which is now `public Socket connect(String host, int
     portNumber, Properties props)'; therefore, any third-party socket
     factories will have to be changed to support this signature.

     (Bug#4334 (http://bugs.mysql.com/4334))

   * Logical connections created by `MysqlConnectionPoolDataSource'
     will now issue a `rollback()' when they are closed and sent back
     to the pool. If your application server/connection pool already
     does this for you, you can set the `rollbackOnPooledClose'
     property to `false' to avoid the overhead of an extra `rollback()'.
     (Bug#4334 (http://bugs.mysql.com/4334))

   * `StringUtils.escapeEasternUnicodeByteStream' was still broken for
     GBK.  (Bug#4010 (http://bugs.mysql.com/4010))


File: manual.info,  Node: cj-news-3-0-14,  Next: cj-news-3-0-13,  Prev: cj-news-3-0-15,  Up: cg-news-3-0

C.7.4.4 Changes in MySQL Connector/J 3.0.14 (28 May 2004)
.........................................................

Bugs fixed:

   * Fixed URL parsing error.


File: manual.info,  Node: cj-news-3-0-13,  Next: cj-news-3-0-12,  Prev: cj-news-3-0-14,  Up: cg-news-3-0

C.7.4.5 Changes in MySQL Connector/J 3.0.13 (27 May 2004)
.........................................................

Bugs fixed:

   * `No Database Selected' when using `MysqlConnectionPoolDataSource'.
     (Bug#3920 (http://bugs.mysql.com/3920))

   * `PreparedStatement.getGeneratedKeys()' method returns only 1
     result for batched insertions.  (Bug#3873
     (http://bugs.mysql.com/3873))

   * Using a `MySQLDatasource' without server name fails.  (Bug#3848
     (http://bugs.mysql.com/3848))


File: manual.info,  Node: cj-news-3-0-12,  Next: cj-news-3-0-11,  Prev: cj-news-3-0-13,  Up: cg-news-3-0

C.7.4.6 Changes in MySQL Connector/J 3.0.12 (18 May 2004)
.........................................................

Bugs fixed:

   * Inconsistent reporting of data type. The server still doesn't
     return all types for *BLOBs *TEXT correctly, so the driver won't
     return those correctly.  (Bug#3570 (http://bugs.mysql.com/3570))

   * `UpdatableResultSet' not picking up default values for
     `moveToInsertRow()'.  (Bug#3557 (http://bugs.mysql.com/3557))

   * Not specifying database in URL caused `MalformedURL' exception.
     (Bug#3554 (http://bugs.mysql.com/3554))

   * Auto-convert MySQL encoding names to Java encoding names if used
     for `characterEncoding' property.  (Bug#3554
     (http://bugs.mysql.com/3554))

   * Use `junit.textui.TestRunner' for all unit tests (to allow them to
     be run from the command line outside of Ant or Eclipse).
     (Bug#3554 (http://bugs.mysql.com/3554))

   * Added encoding names that are recognized on some JVMs to fix case
     where they were reverse-mapped to MySQL encoding names incorrectly.
     (Bug#3554 (http://bugs.mysql.com/3554))

   * Made `StringRegressionTest' 4.1-unicode aware.  (Bug#3520
     (http://bugs.mysql.com/3520))

   * Fixed regression in `PreparedStatement.setString()' and eastern
     character encodings.  (Bug#3520 (http://bugs.mysql.com/3520))

   * `DBMD.getSQLStateType()' returns incorrect value.  (Bug#3520
     (http://bugs.mysql.com/3520))

   * Renamed `StringUtils.escapeSJISByteStream()' to more appropriate
     `escapeEasternUnicodeByteStream()'.  (Bug#3511
     (http://bugs.mysql.com/3511))

   * `StringUtils.escapeSJISByteStream()' not covering all eastern
     double-byte charsets correctly.  (Bug#3511
     (http://bugs.mysql.com/3511))

   * Return creating statement for `ResultSets' created by
     `getGeneratedKeys()'.  (Bug#2957 (http://bugs.mysql.com/2957))

   * Use `SET character_set_results' during initialization to allow any
     charset to be returned to the driver for result sets.  (Bug#2670
     (http://bugs.mysql.com/2670))

   * Don't truncate *Note `BLOB': blob. or `CLOB' values when using
     `setBytes()' and/or `setBinary/CharacterStream()'. .  (Bug#2670
     (http://bugs.mysql.com/2670))

   * Dynamically configure character set mappings for field-level
     character sets on MySQL-4.1.0 and newer using *Note `SHOW
     COLLATION': show-collation. when connecting.  (Bug#2670
     (http://bugs.mysql.com/2670))

   * Map `binary' character set to `US-ASCII' to support *Note
     `DATETIME': datetime. charset recognition for servers >= 4.1.2.
     (Bug#2670 (http://bugs.mysql.com/2670))

   * Use `charsetnr' returned during connect to encode queries before
     issuing `SET NAMES' on MySQL >= 4.1.0.  (Bug#2670
     (http://bugs.mysql.com/2670))

   * Add helper methods to `ResultSetMetaData'
     (`getColumnCharacterEncoding()' and `getColumnCharacterSet()') to
     allow end-users to see what charset the driver thinks it should be
     using for the column.  (Bug#2670 (http://bugs.mysql.com/2670))

   * Only set `character_set_results' for MySQL >= 4.1.0.  (Bug#2670
     (http://bugs.mysql.com/2670))

   * Allow `url' parameter for `MysqlDataSource' and
     `MysqlConnectionPool' `DataSource' so that passing of other
     properties is possible from inside appservers.

   * Don't escape SJIS/GBK/BIG5 when using MySQL-4.1 or newer.

   * Backport documentation tooling from 3.1 branch.

   * Added `failOverReadOnly' property, to allow end-user to configure
     state of connection (read-only/writable) when failed over.

   * Allow `java.util.Date' to be sent in as parameter to
     `PreparedStatement.setObject()', converting it to a `Timestamp' to
     maintain full precision. .  (Bug#103 (http://bugs.mysql.com/103))

   * Add unsigned attribute to `DatabaseMetaData.getColumns()' output
     in the `TYPE_NAME' column.

   * Map duplicate key and foreign key errors to SQLState of `23000'.

   * Backported `change user' and `reset server state' functionality
     from 3.1 branch, to allow clients of
     `MysqlConnectionPoolDataSource' to reset server state on
     `getConnection()' on a pooled connection.


File: manual.info,  Node: cj-news-3-0-11,  Next: cj-news-3-0-10,  Prev: cj-news-3-0-12,  Up: cg-news-3-0

C.7.4.7 Changes in MySQL Connector/J 3.0.11 (19 February 2004)
..............................................................

Bugs fixed:

   * Return `java.lang.Double' for *Note `FLOAT': numeric-types. type
     from `ResultSetMetaData.getColumnClassName()'.  (Bug#2855
     (http://bugs.mysql.com/2855))

   * Return `[B' instead of `java.lang.Object' for *Note `BINARY':
     binary-varbinary, *Note `VARBINARY': binary-varbinary. and
     `LONGVARBINARY' types from
     `ResultSetMetaData.getColumnClassName()' (JDBC compliance).
     (Bug#2855 (http://bugs.mysql.com/2855))

   * Issue connection events on all instances created from a
     `ConnectionPoolDataSource'.  (Bug#2855
     (http://bugs.mysql.com/2855))

   * Return `java.lang.Integer' for *Note `TINYINT': numeric-types. and
     *Note `SMALLINT': numeric-types. types from
     `ResultSetMetaData.getColumnClassName()'.  (Bug#2852
     (http://bugs.mysql.com/2852))

   * Added `useUnbufferedInput' parameter, and now use it by default
     (due to JVM issue
     `http://developer.java.sun.com/developer/bugParade/bugs/4401235.html')
     (Bug#2578 (http://bugs.mysql.com/2578))

   * Fixed failover always going to last host in list.  (Bug#2578
     (http://bugs.mysql.com/2578))

   * Detect `on'/`off' or `1', `2', `3' form of `lower_case_table_names'
     value on server.  (Bug#2578 (http://bugs.mysql.com/2578))

   * `AutoReconnect' time was growing faster than exponentially.
     (Bug#2447 (http://bugs.mysql.com/2447))

   * Trigger a `SET NAMES utf8' when encoding is forced to `utf8' _or_
     `utf-8' via the `characterEncoding' property. Previously, only the
     Java-style encoding name of `utf-8' would trigger this.


File: manual.info,  Node: cj-news-3-0-10,  Next: cj-news-3-0-9,  Prev: cj-news-3-0-11,  Up: cg-news-3-0

C.7.4.8 Changes in MySQL Connector/J 3.0.10 (13 January 2004)
.............................................................

Bugs fixed:

   * Enable caching of the parsing stage of prepared statements via the
     `cachePrepStmts', `prepStmtCacheSize', and `prepStmtCacheSqlLimit'
     properties (disabled by default).  (Bug#2006
     (http://bugs.mysql.com/2006))

   * Fixed security exception when used in Applets (applets can't read
     the system property `file.encoding' which is needed for *Note
     `LOAD DATA LOCAL INFILE': load-data.).  (Bug#2006
     (http://bugs.mysql.com/2006))

   * Speed up parsing of `PreparedStatements', try to use one-pass
     whenever possible.  (Bug#2006 (http://bugs.mysql.com/2006))

   * Fixed exception `Unknown character set 'danish'' on connect with
     JDK-1.4.0 (Bug#2006 (http://bugs.mysql.com/2006))

   * Fixed mappings in SQLError to report deadlocks with SQLStates of
     `41000'.  (Bug#2006 (http://bugs.mysql.com/2006))

   * Removed static synchronization bottleneck from instance factory
     method of `SingleByteCharsetConverter'.  (Bug#2006
     (http://bugs.mysql.com/2006))

   * Removed static synchronization bottleneck from
     `PreparedStatement.setTimestamp()'.  (Bug#2006
     (http://bugs.mysql.com/2006))

   * `ResultSet.findColumn()' should use first matching column name
     when there are duplicate column names in *Note `SELECT': select.
     query (JDBC-compliance).  (Bug#2006 (http://bugs.mysql.com/2006))

   * `maxRows' property would affect internal statements, so check it
     for all statement creation internal to the driver, and set to 0
     when it is not.  (Bug#2006 (http://bugs.mysql.com/2006))

   * Use constants for SQLStates.  (Bug#2006
     (http://bugs.mysql.com/2006))

   * Map charset `ko18_ru' to `ko18r' when connected to MySQL-4.1.0 or
     newer.  (Bug#2006 (http://bugs.mysql.com/2006))

   * Ensure that `Buffer.writeString()' saves room for the `\0'.
     (Bug#2006 (http://bugs.mysql.com/2006))

   * `ArrayIndexOutOfBounds' when parameter number == number of
     parameters + 1.  (Bug#1958 (http://bugs.mysql.com/1958))

   * Connection property `maxRows' not honored.  (Bug#1933
     (http://bugs.mysql.com/1933))

   * Statements being created too many times in
     `DBMD.extractForeignKeyFromCreateTable()'.  (Bug#1925
     (http://bugs.mysql.com/1925))

   * Support escape sequence {fn convert ... }.  (Bug#1914
     (http://bugs.mysql.com/1914))

   * Implement `ResultSet.updateClob()'.  (Bug#1913
     (http://bugs.mysql.com/1913))

   * Autoreconnect code didn't set catalog upon reconnect if it had
     been changed.  (Bug#1913 (http://bugs.mysql.com/1913))

   * `ResultSet.getObject()' on *Note `TINYINT': numeric-types. and
     *Note `SMALLINT': numeric-types. columns should return Java type
     `Integer'.  (Bug#1913 (http://bugs.mysql.com/1913))

   * Added more descriptive error message `Server Configuration Denies
     Access to DataSource', as well as retrieval of message from server.
     (Bug#1913 (http://bugs.mysql.com/1913))

   * `ResultSetMetaData.isCaseSensitive()' returned wrong value for
     *Note `CHAR': char./*Note `VARCHAR': char.  columns.  (Bug#1913
     (http://bugs.mysql.com/1913))

   * Added `alwaysClearStream' connection property, which causes the
     driver to always empty any remaining data on the input stream
     before each query.  (Bug#1913 (http://bugs.mysql.com/1913))

   * `DatabaseMetaData.getSystemFunction()' returning bad function
     `VResultsSion'.  (Bug#1775 (http://bugs.mysql.com/1775))

   * Foreign Keys column sequence is not consistent in
     `DatabaseMetaData.getImported/Exported/CrossReference()'.
     (Bug#1731 (http://bugs.mysql.com/1731))

   * Fix for `ArrayIndexOutOfBounds' exception when using
     `Statement.setMaxRows()'.  (Bug#1695 (http://bugs.mysql.com/1695))

   * Subsequent call to `ResultSet.updateFoo()' causes NPE if result
     set is not updatable.  (Bug#1630 (http://bugs.mysql.com/1630))

   * Fix for 4.1.1-style authentication with no password.  (Bug#1630
     (http://bugs.mysql.com/1630))

   * Cross-database updatable result sets are not checked for
     updatability correctly.  (Bug#1592 (http://bugs.mysql.com/1592))

   * `DatabaseMetaData.getColumns()' should return `Types.LONGVARCHAR'
     for MySQL *Note `LONGTEXT': blob. type.  (Bug#1592
     (http://bugs.mysql.com/1592))

   * Fixed regression of `Statement.getGeneratedKeys()' and *Note
     `REPLACE': replace. statements.  (Bug#1576
     (http://bugs.mysql.com/1576))

   * Barge blobs and split packets not being read correctly.  (Bug#1576
     (http://bugs.mysql.com/1576))

   * Backported fix for aliased tables and `UpdatableResultSets' in
     `checkUpdatability()' method from 3.1 branch.  (Bug#1534
     (http://bugs.mysql.com/1534))

   * `Friendlier' exception message for `PacketTooLargeException'.
     (Bug#1534 (http://bugs.mysql.com/1534))

   * Don't count quoted IDs when inside a 'string' in
     `PreparedStatement' parsing.  (Bug#1511
     (http://bugs.mysql.com/1511))


File: manual.info,  Node: cj-news-3-0-9,  Next: cj-news-3-0-8,  Prev: cj-news-3-0-10,  Up: cg-news-3-0

C.7.4.9 Changes in MySQL Connector/J 3.0.9 (07 October 2003)
............................................................

Bugs fixed:

   * `ResultSet.get/setString' mashing char 127.  (Bug#1247
     (http://bugs.mysql.com/1247))

   * Added property to `clobber' streaming results, by setting the
     `clobberStreamingResults' property to `true' (the default is
     `false'). This will cause a `streaming' `ResultSet' to be
     automatically closed, and any oustanding data still streaming from
     the server to be discarded if another query is executed before all
     the data has been read from the server.  (Bug#1247
     (http://bugs.mysql.com/1247))

   * Added `com.mysql.jdbc.util.BaseBugReport' to help creation of
     testcases for bug reports.  (Bug#1247 (http://bugs.mysql.com/1247))

   * Backported authentication changes for 4.1.1 and newer from 3.1
     branch.  (Bug#1247 (http://bugs.mysql.com/1247))

   * Made `databaseName', `portNumber', and `serverName' optional
     parameters for `MysqlDataSourceFactory'.  (Bug#1246
     (http://bugs.mysql.com/1246))

   * Optimized `CLOB.setChracterStream()'.  (Bug#1131
     (http://bugs.mysql.com/1131))

   * Fixed `CLOB.truncate()'.  (Bug#1130 (http://bugs.mysql.com/1130))

   * Fixed deadlock issue with `Statement.setMaxRows()'.  (Bug#1099
     (http://bugs.mysql.com/1099))

   * `DatabaseMetaData.getColumns()' getting confused about the keyword
     `set' in character columns.  (Bug#1099
     (http://bugs.mysql.com/1099))

   * Clip +/- INF (to smallest and largest representative values for
     the type in MySQL) and NaN (to 0) for `setDouble'/`setFloat()', and
     issue a warning on the statement when the server does not support
     +/- INF or NaN.  (Bug#884 (http://bugs.mysql.com/884))

   * Don't fire connection closed events when closing pooled
     connections, or on `PooledConnection.getConnection()' with already
     open connections.  (Bug#884 (http://bugs.mysql.com/884))

   * Double-escaping of `'\'' when charset is SJIS or GBK and `'\''
     appears in non-escaped input.  (Bug#879
     (http://bugs.mysql.com/879))

   * When emptying input stream of unused rows for `streaming' result
     sets, have the current thread `yield()' every 100 rows in order to
     not monopolize CPU time.  (Bug#879 (http://bugs.mysql.com/879))

   * Issue exception on `ResultSet.getXXX()' on empty result set
     (wasn't caught in some cases).  (Bug#848
     (http://bugs.mysql.com/848))

   * Don't hide messages from exceptions thrown in I/O layers.
     (Bug#848 (http://bugs.mysql.com/848))

   * Fixed regression in large split-packet handling.  (Bug#848
     (http://bugs.mysql.com/848))

   * Better diagnostic error messages in exceptions for `streaming'
     result sets.  (Bug#848 (http://bugs.mysql.com/848))

   * Don't change timestamp TZ twice if `useTimezone==true'.  (Bug#774
     (http://bugs.mysql.com/774))

   * Don't wrap `SQLExceptions' in `RowDataDynamic'.  (Bug#688
     (http://bugs.mysql.com/688))

   * Don't try and reset isolation level on reconnect if MySQL doesn't
     support them.  (Bug#688 (http://bugs.mysql.com/688))

   * The `insertRow' in an `UpdatableResultSet' is now loaded with the
     default column values when `moveToInsertRow()' is called.
     (Bug#688 (http://bugs.mysql.com/688))

   * `DatabaseMetaData.getColumns()' wasn't returning `NULL' for
     default values that are specified as `NULL'.  (Bug#688
     (http://bugs.mysql.com/688))

   * Change default statement type/concurrency to `TYPE_FORWARD_ONLY'
     and `CONCUR_READ_ONLY' (spec compliance).  (Bug#688
     (http://bugs.mysql.com/688))

   * Fix `UpdatableResultSet' to return values for `getXXX()' when on
     insert row.  (Bug#675 (http://bugs.mysql.com/675))

   * Support `InnoDB' contraint names when extracting foreign key
     information in `DatabaseMetaData' (implementing ideas from
     Parwinder Sekhon).  (Bug#664 (http://bugs.mysql.com/664), Bug#517
     (http://bugs.mysql.com/517))

   * Backported 4.1 protocol changes from 3.1 branch (server-side SQL
     states, new field information, larger client capability flags,
     connect-with-database, and so forth).  (Bug#664
     (http://bugs.mysql.com/664), Bug#517 (http://bugs.mysql.com/517))

   * `refreshRow' didn't work when primary key values contained values
     that needed to be escaped (they ended up being doubly escaped).
     (Bug#661 (http://bugs.mysql.com/661))

   * Fixed `ResultSet.previous()' behavior to move current position to
     before result set when on first row of result set.  (Bug#496
     (http://bugs.mysql.com/496))

   * Fixed `Statement' and `PreparedStatement' issuing bogus queries
     when `setMaxRows()' had been used and a `LIMIT' clause was present
     in the query.  (Bug#496 (http://bugs.mysql.com/496))

   * Faster date handling code in `ResultSet' and `PreparedStatement'
     (no longer uses `Date' methods that synchronize on static
     calendars).

   * Fixed test for end of buffer in `Buffer.readString()'.


File: manual.info,  Node: cj-news-3-0-8,  Next: cj-news-3-0-7,  Prev: cj-news-3-0-9,  Up: cg-news-3-0

C.7.4.10 Changes in MySQL Connector/J 3.0.8 (23 May 2003)
.........................................................

Bugs fixed:

   * Fixed SJIS encoding bug, thanks to Naoto Sato.  (Bug#378
     (http://bugs.mysql.com/378))

   * Fix problem detecting server character set in some cases.
     (Bug#378 (http://bugs.mysql.com/378))

   * Allow multiple calls to `Statement.close()'.  (Bug#378
     (http://bugs.mysql.com/378))

   * Return correct number of generated keys when using *Note
     `REPLACE': replace. statements.  (Bug#378
     (http://bugs.mysql.com/378))

   * Unicode character 0xFFFF in a string would cause the driver to
     throw an `ArrayOutOfBoundsException'. .  (Bug#378
     (http://bugs.mysql.com/378))

   * Fix row data decoding error when using _very_ large packets.
     (Bug#378 (http://bugs.mysql.com/378))

   * Optimized row data decoding.  (Bug#378 (http://bugs.mysql.com/378))

   * Issue exception when operating on an already closed prepared
     statement.  (Bug#378 (http://bugs.mysql.com/378))

   * Optimized usage of `EscapeProcessor'.  (Bug#378
     (http://bugs.mysql.com/378))

   * Use JVM charset with file names and `LOAD DATA [LOCAL] INFILE'.

   * Fix infinite loop with `Connection.cleanup()'.

   * Changed Ant target `compile-core' to `compile-driver', and made
     testsuite compilation a separate target.

   * Fixed result set not getting set for `Statement.executeUpdate()',
     which affected `getGeneratedKeys()' and `getUpdateCount()' in some
     cases.

   * Return list of generated keys when using multi-value `INSERTS' with
     `Statement.getGeneratedKeys()'.

   * Allow bogus URLs in `Driver.getPropertyInfo()'.


File: manual.info,  Node: cj-news-3-0-7,  Next: cj-news-3-0-6,  Prev: cj-news-3-0-8,  Up: cg-news-3-0

C.7.4.11 Changes in MySQL Connector/J 3.0.7 (08 April 2003)
...........................................................

Bugs fixed:

   * Fixed charset issues with database metadata (charset was not
     getting set correctly).

   * You can now toggle profiling on/off using
     `Connection.setProfileSql(boolean)'.

   * 4.1 Column Metadata fixes.

   * Fixed `MysqlPooledConnection.close()' calling wrong event type.

   * Fixed `StringIndexOutOfBoundsException' in
     `PreparedStatement.setClob()'.

   * `IOExceptions' during a transaction now cause the `Connection' to
     be closed.

   * Remove synchronization from `Driver.connect()' and
     `Driver.acceptsUrl()'.

   * Fixed missing conversion for *Note `YEAR': year.  type in
     `ResultSetMetaData.getColumnTypeName()'.

   * Updatable `ResultSets' can now be created for aliased
     tables/columns when connected to MySQL-4.1 or newer.

   * Fixed *Note `LOAD DATA LOCAL INFILE': load-data. bug when file >
     `max_allowed_packet'.

   * Don't pick up indexes that start with `pri' as primary keys for
     `DBMD.getPrimaryKeys()'.

   * Ensure that packet size from `alignPacketSize()' does not exceed
     `max_allowed_packet' (JVM bug)

   * Don't reset `Connection.isReadOnly()' when autoReconnecting.

   * Fixed escaping of 0x5c (`'\'') character for GBK and Big5 charsets.

   * Fixed `ResultSet.getTimestamp()' when underlying field is of type
     *Note `DATE': datetime.

   * Throw `SQLExceptions' when trying to do operations on a forcefully
     closed `Connection' (that is, when a communication link failure
     occurs).


File: manual.info,  Node: cj-news-3-0-6,  Next: cj-news-3-0-5,  Prev: cj-news-3-0-7,  Up: cg-news-3-0

C.7.4.12 Changes in MySQL Connector/J 3.0.6 (18 February 2003)
..............................................................

Bugs fixed:

   * Backported 4.1 charset field info changes from Connector/J 3.1.

   * Fixed `Statement.setMaxRows()' to stop sending `LIMIT' type
     queries when not needed (performance).

   * Fixed `DBMD.getTypeInfo()' and `DBMD.getColumns()' returning
     different value for precision in *Note `TEXT': blob. and *Note
     `BLOB': blob. types.

   * Fixed `SQLExceptions' getting swallowed on initial connect.

   * Fixed `ResultSetMetaData' to return `""' when catalog not known.
     Fixes `NullPointerExceptions' with Sun's `CachedRowSet'.

   * Allow ignoring of warning for `non transactional tables' during
     rollback (compliance/usability) by setting `ignoreNonTxTables'
     property to `true'.

   * Clean up `Statement' query/method mismatch tests (that is, *Note
     `INSERT': insert. not allowed with `.executeQuery()').

   * Fixed `ResultSetMetaData.isWritable()' to return correct value.

   * More checks added in `ResultSet' traversal method to catch when in
     closed state.

   * Implemented `Blob.setBytes()'. You still need to pass the
     resultant `Blob' back into an updatable `ResultSet' or
     `PreparedStatement' to persist the changes, because MySQL does not
     support `locators'.

   * Add `window' of different `NULL' sorting behavior to
     `DBMD.nullsAreSortedAtStart' (4.0.2 to 4.0.10, true; otherwise,
     no).


File: manual.info,  Node: cj-news-3-0-5,  Next: cj-news-3-0-4,  Prev: cj-news-3-0-6,  Up: cg-news-3-0

C.7.4.13 Changes in MySQL Connector/J 3.0.5 (22 January 2003)
.............................................................

Bugs fixed:

   * Fixed `ResultSet.isBeforeFirst()' for empty result sets.

   * Added missing *Note `LONGTEXT': blob. type to `DBMD.getColumns()'.

   * Implemented an empty `TypeMap' for `Connection.getTypeMap()' so
     that some third-party apps work with MySQL (IBM WebSphere 5.0
     Connection pool).

   * Added update options for foreign key metadata.

   * Fixed `Buffer.fastSkipLenString()' causing `ArrayIndexOutOfBounds'
     exceptions with some queries when unpacking fields.

   * Quote table names in `DatabaseMetaData.getColumns()',
     `getPrimaryKeys()', `getIndexInfo()', `getBestRowIdentifier()'.

   * Retrieve `TX_ISOLATION' from database for
     `Connection.getTransactionIsolation()' when the MySQL version
     supports it, instead of an instance variable.

   * Greatly reduce memory required for `setBinaryStream()' in
     `PreparedStatements'.


File: manual.info,  Node: cj-news-3-0-4,  Next: cj-news-3-0-3,  Prev: cj-news-3-0-5,  Up: cg-news-3-0

C.7.4.14 Changes in MySQL Connector/J 3.0.4 (06 January 2003)
.............................................................

Bugs fixed:

   * Streamlined character conversion and `byte[]' handling in
     `PreparedStatements' for `setByte()'.

   * Fixed `PreparedStatement.executeBatch()' parameter overwriting.

   * Added quoted identifiers to database names for
     `Connection.setCatalog'.

   * Added support for 4.0.8-style large packets.

   * Reduce memory footprint of `PreparedStatements' by sharing
     outbound packet with `MysqlIO'.

   * Added `strictUpdates' property to allow control of amount of
     checking for `correctness' of updatable result sets. Set this to
     `false' if you want faster updatable result sets and you know that
     you create them from *Note `SELECT': select.  statements on tables
     with primary keys and that you have selected all primary keys in
     your query.

   * Added support for quoted identifiers in `PreparedStatement' parser.


File: manual.info,  Node: cj-news-3-0-3,  Next: cj-news-3-0-2,  Prev: cj-news-3-0-4,  Up: cg-news-3-0

C.7.4.15 Changes in MySQL Connector/J 3.0.3 (17 December 2002)
..............................................................

Bugs fixed:

   * Allow user to alter behavior of `Statement'/
     `PreparedStatement.executeBatch()' via `continueBatchOnError'
     property (defaults to `true').

   * More robust escape tokenizer: Recognize `--' comments, and allow
     nested escape sequences (see `testsuite.EscapeProcessingTest').

   * Fixed `Buffer.isLastDataPacket()' for 4.1 and newer servers.

   * `NamedPipeSocketFactory' now works (only intended for Windows),
     see `README' for instructions.

   * Changed `charsToByte' in `SingleByteCharConverter' to be
     non-static.

   * Use non-aliased table/column names and database names to fully
     qualify tables and columns in `UpdatableResultSet' (requires
     MySQL-4.1 or newer).

   * `LOAD DATA LOCAL INFILE ...' now works, if your server is
     configured to allow it. Can be turned off with the
     `allowLoadLocalInfile' property (see the `README').

   * Implemented `Connection.nativeSQL()'.

   * Fixed `ResultSetMetaData.getColumnTypeName()' returning *Note
     `BLOB': blob. for *Note `TEXT': blob. and *Note `TEXT': blob. for
     *Note `BLOB': blob. types.

   * Fixed charset handling in `Fields.java'.

   * Because of above, implemented
     `ResultSetMetaData.isAutoIncrement()' to use
     `Field.isAutoIncrement()'.

   * Substitute `'?'' for unknown character conversions in single-byte
     character sets instead of `'\0''.

   * Added `CLIENT_LONG_FLAG' to be able to get more column flags
     (`isAutoIncrement()' being the most important).

   * Honor `lower_case_table_names' when enabled in the server when
     doing table name comparisons in `DatabaseMetaData' methods.

   * `DBMD.getImported/ExportedKeys()' now handles multiple foreign
     keys per table.

   * More robust implementation of updatable result sets. Checks that
     _all_ primary keys of the table have been selected.

   * Some MySQL-4.1 protocol support (extended field info from selects).

   * Check for connection closed in more `Connection' methods
     (`createStatement', `prepareStatement', `setTransactionIsolation',
     `setAutoCommit').

   * Fixed `ResultSetMetaData.getPrecision()' returning incorrect
     values for some floating-point types.

   * Changed `SingleByteCharConverter' to use lazy initialization of
     each converter.


File: manual.info,  Node: cj-news-3-0-2,  Next: cj-news-3-0-1,  Prev: cj-news-3-0-3,  Up: cg-news-3-0

C.7.4.16 Changes in MySQL Connector/J 3.0.2 (08 November 2002)
..............................................................

Bugs fixed:

   * Implemented `Clob.setString()'.

   * Added `com.mysql.jdbc.MiniAdmin' class, which allows you to send
     `shutdown' command to MySQL server. This is intended to be used
     when `embedding' Java and MySQL server together in an end-user
     application.

   * Added SSL support. See `README' for information on how to use it.

   * All `DBMD' result set columns describing schemas now return `NULL'
     to be more compliant with the behavior of other JDBC drivers for
     other database systems (MySQL does not support schemas).

   * Use *Note `SHOW CREATE TABLE': show-create-table. when possible
     for determining foreign key information for `DatabaseMetaData'.
     Also allows cascade options for *Note `DELETE': delete.
     information to be returned.

   * Implemented `Clob.setCharacterStream()'.

   * Failover and `autoReconnect' work only when the connection is in
     an `autoCommit(false)' state, in order to stay transaction-safe.

   * Fixed `DBMD.supportsResultSetConcurrency()' so that it returns
     `true' for `ResultSet.TYPE_SCROLL_INSENSITIVE' and
     `ResultSet.CONCUR_READ_ONLY' or `ResultSet.CONCUR_UPDATABLE'.

   * Implemented `Clob.setAsciiStream()'.

   * Removed duplicate code from `UpdatableResultSet' (it can be
     inherited from `ResultSet', the extra code for each method to
     handle updatability I thought might someday be necessary has not
     been needed).

   * Fixed `UnsupportedEncodingException' thrown when `forcing' a
     character encoding via properties.

   * Fixed incorrect conversion in `ResultSet.getLong()'.

   * Implemented `ResultSet.updateBlob()'.

   * Removed some not-needed temporary object creation by smarter use
     of `Strings' in `EscapeProcessor', `Connection' and
     `DatabaseMetaData' classes.

   * Escape `0x5c' character in strings for the SJIS charset.

   * `PreparedStatement' now honors stream lengths in
     setBinary/Ascii/Character Stream() unless you set the connection
     property `useStreamLengthsInPrepStmts' to `false'.

   * Fixed issue with updatable result sets and `PreparedStatements'
     not working.

   * Fixed start position off-by-1 error in `Clob.getSubString()'.

   * Added `connectTimeout' parameter that allows users of JDK-1.4 and
     newer to specify a maximum time to wait to establish a connection.

   * Fixed various non-ASCII character encoding issues.

   * Fixed `ResultSet.isLast()' for empty result sets (should return
     `false').

   * Added driver property `useHostsInPrivileges'.  Defaults to `true'.
     Affects whether or not `@hostname' will be used in
     `DBMD.getColumn/TablePrivileges'.

   * Fixed `ResultSet.setFetchDirection(FETCH_UNKNOWN)'.

   * Added `queriesBeforeRetryMaster' property that specifies how many
     queries to issue when failed over before attempting to reconnect
     to the master (defaults to 50).

   * Fixed issue when calling `Statement.setFetchSize()' when using
     arbitrary values.

   * Properly restore connection properties when autoReconnecting or
     failing-over, including `autoCommit' state, and isolation level.

   * Implemented `Clob.truncate()'.


File: manual.info,  Node: cj-news-3-0-1,  Next: cj-news-3-0-0,  Prev: cj-news-3-0-2,  Up: cg-news-3-0

C.7.4.17 Changes in MySQL Connector/J 3.0.1 (21 September 2002)
...............................................................

Bugs fixed:

   * Charsets now automatically detected. Optimized code for
     single-byte character set conversion.

   * Fixed `ResultSetMetaData.isSigned()' for *Note `TINYINT':
     numeric-types. and *Note `BIGINT': numeric-types.

   * Fixed `RowDataStatic.getAt()' off-by-one bug.

   * Fixed `ResultSet.getRow()' off-by-one bug.

   * Massive code clean-up to follow Java coding conventions (the time
     had come).

   * Implemented `ResultSet.getCharacterStream()'.

   * Added limited `Clob' functionality (`ResultSet.getClob()',
     `PreparedStatemtent.setClob()',
     `PreparedStatement.setObject(Clob)'.

   * `Connection.isClosed()' no longer `pings' the server.

   * `Connection.close()' issues `rollback()' when `getAutoCommit()' is
     `false'.

   * Added `socketTimeout' parameter to URL.

   * Added `LOCAL TEMPORARY' to table types in
     `DatabaseMetaData.getTableTypes()'.

   * Added `paranoid' parameter, which sanitizes error messages by
     removing `sensitive' information from them (such as host names,
     ports, or user names), as well as clearing `sensitive' data
     structures when possible.


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C.7.4.18 Changes in MySQL Connector/J 3.0.0 (31 July 2002)
..........................................................

Bugs fixed:

   * General source-code cleanup.

   * The driver now only works with JDK-1.2 or newer.

   * Fix and sort primary key names in `DBMetaData' (SF bugs 582086 and
     582086).

   * `ResultSet.getTimestamp()' now works for *Note `DATE': datetime.
     types (SF bug 559134).

   * Float types now reported as `java.sql.Types.FLOAT' (SF bug 579573).

   * Support for streaming (row-by-row) result sets (see `README')
     Thanks to Doron.

   * Testsuite now uses Junit (which you can get from
     `http://www.junit.org'.

   * JDBC Compliance: Passes all tests besides stored procedure tests.

   * `ResultSet.getDate/Time/Timestamp' now recognizes all forms of
     invalid values that have been set to all zeros by MySQL (SF bug
     586058).

   * Added multi-host failover support (see `README').

   * Repackaging: New driver name is `com.mysql.jdbc.Driver', old name
     still works, though (the driver is now provided by MySQL-AB).

   * Support for large packets (new addition to MySQL-4.0 protocol),
     see `README' for more information.

   * Better checking for closed connections in `Statement' and
     `PreparedStatement'.

   * Performance improvements in string handling and field metadata
     creation (lazily instantiated) contributed by Alex
     Twisleton-Wykeham-Fiennes.

   * JDBC-3.0 functionality including
     `Statement/PreparedStatement.getGeneratedKeys()' and
     `ResultSet.getURL()'.

   * Overall speed improvements via controlling transient object
     creation in `MysqlIO' class when reading packets.

   * *!!! LICENSE CHANGE !!!* The driver is now GPL. If you need
     non-GPL licenses, please contact me `<mark@mysql.com>'.

   * Performance enchancements: Driver is now 50-100% faster in most
     situations, and creates fewer temporary objects.


File: manual.info,  Node: cj-news-2-0,  Next: cj-news-1-2b,  Prev: cg-news-3-0,  Up: cj-news

C.7.5 Changes in MySQL Connector/J 2.0.x
----------------------------------------

* Menu:

* cj-news-2-0-14::               Changes in MySQL Connector/J 2.0.14 (16 May 2002)
* cj-news-2-0-13::               Changes in MySQL Connector/J 2.0.13 (24 April 2002)
* cj-news-2-0-12::               Changes in MySQL Connector/J 2.0.12 (07 April 2002)
* cj-news-2-0-11::               Changes in MySQL Connector/J 2.0.11 (27 January 2002)
* cj-news-2-0-10::               Changes in MySQL Connector/J 2.0.10 (24 January 2002)
* cj-news-2-0-9::                Changes in MySQL Connector/J 2.0.9 (13 January 2002)
* cj-news-2-0-8::                Changes in MySQL Connector/J 2.0.8 (25 November 2001)
* cj-news-2-0-7::                Changes in MySQL Connector/J 2.0.7 (24 October 2001)
* cj-news-2-0-6::                Changes in MySQL Connector/J 2.0.6 (16 June 2001)
* cj-news-2-0-5::                Changes in MySQL Connector/J 2.0.5 (13 June 2001)
* cj-news-2-0-3::                Changes in MySQL Connector/J 2.0.3 (03 December 2000)
* cj-news-2-0-1::                Changes in MySQL Connector/J 2.0.1 (06 April 2000)
* cj-news-2-0pre5::              Changes in MySQL Connector/J 2.0.0pre5 (21 February 2000)
* cj-news-2-0pre4::              Changes in MySQL Connector/J 2.0.0pre4 (10 January 2000)
* cj-news-2-0pre::               Changes in MySQL Connector/J 2.0.0pre (17 August 1999)


File: manual.info,  Node: cj-news-2-0-14,  Next: cj-news-2-0-13,  Prev: cj-news-2-0,  Up: cj-news-2-0

C.7.5.1 Changes in MySQL Connector/J 2.0.14 (16 May 2002)
.........................................................

Bugs fixed:

   * `ResultSet.getDouble()' now uses code built into JDK to be more
     precise (but slower).

   * Fixed typo for `relaxAutoCommit' parameter.

   * `LogicalHandle.isClosed()' calls through to physical connection.

   * Added SQL profiling (to `STDERR'). Set `profileSql=true' in your
     JDBC URL. See `README' for more information.

   * `PreparedStatement' now releases resources on `.close()'. (SF bug
     553268)

   * More code cleanup.

   * Quoted identifiers not used if server version does not support
     them. Also, if server started with `--ansi' or
     `--sql-mode=ANSI_QUOTES', ``"'' will be used as an identifier
     quote character, otherwise ``''' will be used.


File: manual.info,  Node: cj-news-2-0-13,  Next: cj-news-2-0-12,  Prev: cj-news-2-0-14,  Up: cj-news-2-0

C.7.5.2 Changes in MySQL Connector/J 2.0.13 (24 April 2002)
...........................................................

Bugs fixed:

   * Fixed unicode chars being read incorrectly. (SF bug 541088)

   * Faster blob escaping for `PrepStmt'.

   * Added `setURL()' to `MySQLXADataSource'. (SF bug 546019)

   * Added `set'/`getPortNumber()' to `DataSource(s)'. (SF bug 548167)

   * `PreparedStatement.toString()' fixed. (SF bug 534026)

   * More code cleanup.

   * Rudimentary version of `Statement.getGeneratedKeys()' from JDBC-3.0
     now implemented (you need to be using JDK-1.4 for this to work, I
     believe).

   * `DBMetaData.getIndexInfo()' - bad PAGES fixed.  (SF BUG 542201)

   * `ResultSetMetaData.getColumnClassName()' now implemented.


File: manual.info,  Node: cj-news-2-0-12,  Next: cj-news-2-0-11,  Prev: cj-news-2-0-13,  Up: cj-news-2-0

C.7.5.3 Changes in MySQL Connector/J 2.0.12 (07 April 2002)
...........................................................

Bugs fixed:

   * Fixed `testsuite.Traversal' `afterLast()' bug, thanks to Igor
     Lastric.

   * Added new types to `getTypeInfo()', fixed existing types thanks to
     Al Davis and Kid Kalanon.

   * Fixed time zone off-by-1-hour bug in `PreparedStatement' (538286,
     528785).

   * Added identifier quoting to all `DatabaseMetaData' methods that
     need them (should fix 518108).

   * Added support for *Note `BIT': numeric-types. types (51870) to
     `PreparedStatement'.

   * `ResultSet.insertRow()' should now detect auto_increment fields in
     most cases and use that value in the new row. This detection will
     not work in multi-valued keys, however, due to the fact that the
     MySQL protocol does not return this information.

   * Relaxed synchronization in all classes, should fix 520615 and
     520393.

   * `DataSources' - fixed `setUrl' bug (511614, 525565), wrong
     datasource class name (532816, 528767).

   * Added support for *Note `YEAR': year. type (533556).

   * Fixes for `ResultSet' updatability in `PreparedStatement'.

   * `ResultSet': Fixed updatability (values being set to `null' if not
     updated).

   * Added `getTable/ColumnPrivileges()' to DBMD (fixes 484502).

   * Added `getIdleFor()' method to `Connection' and
     `MysqlLogicalHandle'.

   * `ResultSet.refreshRow()' implemented.

   * Fixed `getRow()' bug (527165) in `ResultSet'.

   * General code cleanup.


File: manual.info,  Node: cj-news-2-0-11,  Next: cj-news-2-0-10,  Prev: cj-news-2-0-12,  Up: cj-news-2-0

C.7.5.4 Changes in MySQL Connector/J 2.0.11 (27 January 2002)
.............................................................

Bugs fixed:

   * Full synchronization of `Statement.java'.

   * Fixed missing `DELETE_RULE' value in
     `DBMD.getImported/ExportedKeys()' and `getCrossReference()'.

   * More changes to fix `Unexpected end of input stream' errors when
     reading *Note `BLOB': blob. values. This should be the last fix.


File: manual.info,  Node: cj-news-2-0-10,  Next: cj-news-2-0-9,  Prev: cj-news-2-0-11,  Up: cj-news-2-0

C.7.5.5 Changes in MySQL Connector/J 2.0.10 (24 January 2002)
.............................................................

Bugs fixed:

   * Fixed null-pointer-exceptions when using
     `MysqlConnectionPoolDataSource' with Websphere 4 (bug 505839).

   * Fixed spurious `Unexpected end of input stream' errors in
     `MysqlIO' (bug 507456).


File: manual.info,  Node: cj-news-2-0-9,  Next: cj-news-2-0-8,  Prev: cj-news-2-0-10,  Up: cj-news-2-0

C.7.5.6 Changes in MySQL Connector/J 2.0.9 (13 January 2002)
............................................................

Bugs fixed:

   * Fixed extra memory allocation in `MysqlIO.readPacket()' (bug
     488663).

   * Added detection of network connection being closed when reading
     packets (thanks to Todd Lizambri).

   * Fixed casting bug in `PreparedStatement' (bug 488663).

   * `DataSource' implementations moved to
     `org.gjt.mm.mysql.jdbc2.optional' package, and (initial)
     implementations of `PooledConnectionDataSource' and `XADataSource'
     are in place (thanks to Todd Wolff for the implementation and
     testing of `PooledConnectionDataSource' with IBM WebSphere 4).

   * Fixed quoting error with escape processor (bug 486265).

   * Removed concatenation support from driver (the `||' operator), as
     older versions of VisualAge seem to be the only thing that use it,
     and it conflicts with the logical `||' operator. You will need to
     start *Note `mysqld': mysqld. with the `--ansi' flag to use the
     `||' operator as concatenation (bug 491680).

   * `Ant' build was corrupting included `jar' files, fixed (bug
     487669).

   * Report batch update support through `DatabaseMetaData' (bug
     495101).

   * Implementation of `DatabaseMetaData.getExported/ImportedKeys()'
     and `getCrossReference()'.

   * Fixed off-by-one-hour error in `PreparedStatement.setTimestamp()'
     (bug 491577).

   * Full synchronization on methods modifying instance and
     class-shared references, driver should be entirely thread-safe now
     (please let me know if you have problems).


File: manual.info,  Node: cj-news-2-0-8,  Next: cj-news-2-0-7,  Prev: cj-news-2-0-9,  Up: cj-news-2-0

C.7.5.7 Changes in MySQL Connector/J 2.0.8 (25 November 2001)
.............................................................

Bugs fixed:

   * `XADataSource'/`ConnectionPoolDataSource' code (experimental)

   * `DatabaseMetaData.getPrimaryKeys()' and `getBestRowIdentifier()'
     are now more robust in identifying primary keys (matches
     regardless of case or abbreviation/full spelling of `Primary Key'
     in `Key_type' column).

   * Batch updates now supported (thanks to some inspiration from
     Daniel Rall).

   * `PreparedStatement.setAnyNumericType()' now handles positive
     exponents correctly (adds `+' so MySQL can understand it).


File: manual.info,  Node: cj-news-2-0-7,  Next: cj-news-2-0-6,  Prev: cj-news-2-0-8,  Up: cj-news-2-0

C.7.5.8 Changes in MySQL Connector/J 2.0.7 (24 October 2001)
............................................................

Bugs fixed:

   * Character sets read from database if `useUnicode=true' and
     `characterEncoding' is not set. (thanks to Dmitry Vereshchagin)

   * Initial transaction isolation level read from database (if
     available). (thanks to Dmitry Vereshchagin)

   * Fixed `PreparedStatement' generating SQL that would end up with
     syntax errors for some queries.

   * `PreparedStatement.setCharacterStream()' now implemented

   * Captialize type names when `captializeTypeNames=true' is passed in
     URL or properties (for WebObjects. (thanks to Anjo Krank)

   * `ResultSet.getBlob()' now returns `null' if column value was
     `null'.

   * Fixed `ResultSetMetaData.getPrecision()' returning one less than
     actual on newer versions of MySQL.

   * Fixed dangling socket problem when in high availability
     (`autoReconnect=true') mode, and finalizer for `Connection' will
     close any dangling sockets on GC.

   * Fixed time zone issue in `PreparedStatement.setTimestamp()'.
     (thanks to Erik Olofsson)

   * PreparedStatement.setDouble() now uses full-precision doubles
     (reverting a fix made earlier to truncate them).

   * Fixed `DatabaseMetaData.supportsTransactions()', and
     `supportsTransactionIsolationLevel()' and `getTypeInfo()'
     `SQL_DATETIME_SUB' and `SQL_DATA_TYPE' fields not being readable.

   * Updatable result sets now correctly handle `NULL' values in fields.

   * PreparedStatement.setBoolean() will use 1/0 for values if your
     MySQL version is 3.21.23 or higher.

   * Fixed `ResultSet.isAfterLast()' always returning `false'.


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C.7.5.9 Changes in MySQL Connector/J 2.0.6 (16 June 2001)
.........................................................

Bugs fixed:

   * Fixed `PreparedStatement' parameter checking.

   * Fixed case-sensitive column names in `ResultSet.java'.


File: manual.info,  Node: cj-news-2-0-5,  Next: cj-news-2-0-3,  Prev: cj-news-2-0-6,  Up: cj-news-2-0

C.7.5.10 Changes in MySQL Connector/J 2.0.5 (13 June 2001)
..........................................................

Bugs fixed:

   * `ResultSet.insertRow()' works now, even if not all columns are set
     (they will be set to `NULL').

   * Added `Byte' to `PreparedStatement.setObject()'.

   * Fixed data parsing of *Note `TIMESTAMP': datetime.  values with
     2-digit years.

   * Added `ISOLATION' level support to `Connection.setIsolationLevel()'

   * `DataBaseMetaData.getCrossReference()' no longer `ArrayIndexOOB'.

   * `ResultSet.getBoolean()' now recognizes `-1' as `true'.

   * `ResultSet' has +/-Inf/inf support.

   * `getObject()' on `ResultSet' correctly does *Note `TINYINT':
     numeric-types.->`Byte' and *Note `SMALLINT':
     numeric-types.->`Short'.

   * Fixed `ResultSetMetaData.getColumnTypeName' for *Note `TEXT':
     blob./*Note `BLOB': blob.

   * Fixed `ArrayIndexOutOfBounds' when sending large *Note `BLOB':
     blob. queries. (Max size packet was not being set)

   * Fixed NPE on `PreparedStatement.executeUpdate()' when all columns
     have not been set.

   * Fixed `ResultSet.getBlob()' `ArrayIndex' out-of-bounds.


File: manual.info,  Node: cj-news-2-0-3,  Next: cj-news-2-0-1,  Prev: cj-news-2-0-5,  Up: cj-news-2-0

C.7.5.11 Changes in MySQL Connector/J 2.0.3 (03 December 2000)
..............................................................

Bugs fixed:

   * Fixed composite key problem with updatable result sets.

   * Faster ASCII string operations.

   * Fixed off-by-one error in `java.sql.Blob' implementation code.

   * Fixed incorrect detection of `MAX_ALLOWED_PACKET', so sending
     large blobs should work now.

   * Added detection of -/+INF for doubles.

   * Added `ultraDevHack' URL parameter, set to `true' to allow
     (broken) Macromedia UltraDev to use the driver.

   * Implemented `getBigDecimal()' without scale component for JDBC2.


File: manual.info,  Node: cj-news-2-0-1,  Next: cj-news-2-0pre5,  Prev: cj-news-2-0-3,  Up: cj-news-2-0

C.7.5.12 Changes in MySQL Connector/J 2.0.1 (06 April 2000)
...........................................................

Bugs fixed:

   * Columns that are of type *Note `TEXT': blob. now return as
     `Strings' when you use `getObject()'.

   * Cleaned up exception handling when driver connects.

   * Fixed `RSMD.isWritable()' returning wrong value. Thanks to Moritz
     Maass.

   * `DatabaseMetaData.getPrimaryKeys()' now works correctly with
     respect to `key_seq'. Thanks to Brian Slesinsky.

   * Fixed many JDBC-2.0 traversal, positioning bugs, especially with
     respect to empty result sets. Thanks to Ron Smits, Nick Brook,
     Cessar Garcia and Carlos Martinez.

   * No escape processing is done on `PreparedStatements' anymore per
     JDBC spec.

   * Fixed some issues with updatability support in `ResultSet' when
     using multiple primary keys.


File: manual.info,  Node: cj-news-2-0pre5,  Next: cj-news-2-0pre4,  Prev: cj-news-2-0-1,  Up: cj-news-2-0

C.7.5.13 Changes in MySQL Connector/J 2.0.0pre5 (21 February 2000)
..................................................................

   * Fixed Bad Handshake problem.


File: manual.info,  Node: cj-news-2-0pre4,  Next: cj-news-2-0pre,  Prev: cj-news-2-0pre5,  Up: cj-news-2-0

C.7.5.14 Changes in MySQL Connector/J 2.0.0pre4 (10 January 2000)
.................................................................

   * Fixes to ResultSet for insertRow() - Thanks to Cesar Garcia

   * Fix to Driver to recognize JDBC-2.0 by loading a JDBC-2.0 class,
     instead of relying on JDK version numbers. Thanks to John Baker.

   * Fixed ResultSet to return correct row numbers

   * Statement.getUpdateCount() now returns rows matched, instead of
     rows actually updated, which is more SQL-92 like.

10-29-99

   * Statement/PreparedStatement.getMoreResults() bug fixed.  Thanks to
     Noel J. Bergman.

   * Added Short as a type to PreparedStatement.setObject().  Thanks to
     Jeff Crowder

   * Driver now automagically configures maximum/preferred packet sizes
     by querying server.

   * Autoreconnect code uses fast ping command if server supports it.

   * Fixed various bugs with respect to packet sizing when reading from
     the server and when alloc'ing to write to the server.


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C.7.5.15 Changes in MySQL Connector/J 2.0.0pre (17 August 1999)
...............................................................

   * Now compiles under JDK-1.2. The driver supports both JDK-1.1 and
     JDK-1.2 at the same time through a core set of classes.  The
     driver will load the appropriate interface classes at runtime by
     figuring out which JVM version you are using.

   * Fixes for result sets with all nulls in the first row.  (Pointed
     out by Tim Endres)

   * Fixes to column numbers in SQLExceptions in ResultSet (Thanks to
     Blas Rodriguez Somoza)

   * The database no longer needs to specified to connect.  (Thanks to
     Christian Motschke)


File: manual.info,  Node: cj-news-1-2b,  Next: cg-news-1-0,  Prev: cj-news-2-0,  Up: cj-news

C.7.6 Changes in MySQL Connector/J 1.2b (04 July 1999)
------------------------------------------------------

   * Better Documentation (in progress), in doc/mm.doc/book1.html

   * DBMD now allows null for a column name pattern (not in spec),
     which it changes to '%'.

   * DBMD now has correct types/lengths for getXXX().

   * ResultSet.getDate(), getTime(), and getTimestamp() fixes.
     (contributed by Alan Wilken)

   * EscapeProcessor now handles \{ \} and { or } inside quotes
     correctly. (thanks to Alik for some ideas on how to fix it)

   * Fixes to properties handling in Connection. (contributed by Juho
     Tikkala)

   * ResultSet.getObject() now returns null for NULL columns in the
     table, rather than bombing out. (thanks to Ben Grosman)

   * ResultSet.getObject() now returns Strings for types from MySQL
     that it doesn't know about. (Suggested by Chris Perdue)

   * Removed DataInput/Output streams, not needed, 1/2 number of method
     calls per IO operation.

   * Use default character encoding if one is not specified. This is a
     work-around for broken JVMs, because according to spec, EVERY JVM
     must support "ISO8859_1", but they do not.

   * Fixed Connection to use the platform character encoding instead of
     "ISO8859_1" if one isn't explicitly set. This fixes problems
     people were having loading the character- converter classes that
     didn't always exist (JVM bug). (thanks to Fritz Elfert for
     pointing out this problem)

   * Changed MysqlIO to re-use packets where possible to reduce memory
     usage.

   * Fixed escape-processor bugs pertaining to {} inside quotes.


File: manual.info,  Node: cg-news-1-0,  Prev: cj-news-1-2b,  Up: cj-news

C.7.7 Changes in MySQL Connector/J 1.2.x and lower
--------------------------------------------------

* Menu:

* cj-news-1-2a::                 Changes in MySQL Connector/J 1.2a (14 April 1999)
* cj-news-1-1i::                 Changes in MySQL Connector/J 1.1i (24 March 1999)
* cj-news-1-1h::                 Changes in MySQL Connector/J 1.1h (08 March 1999)
* cj-news-1-1g::                 Changes in MySQL Connector/J 1.1g (19 February 1999)
* cj-news-1-1f::                 Changes in MySQL Connector/J 1.1f (31 December 1998)
* cj-news-1-1b::                 Changes in MySQL Connector/J 1.1b (03 November 1998)
* cj-news-1-1::                  Changes in MySQL Connector/J 1.1 (02 September 1998)
* cj-news-1-0::                  Changes in MySQL Connector/J 1.0 (24 August 1998)
* cj-news-0-9d::                 Changes in MySQL Connector/J 0.9d (04 August 1998)
* cj-news-0-9::                  Changes in MySQL Connector/J 0.9 (28 July 1998)
* cj-news-0-8::                  Changes in MySQL Connector/J 0.8 (06 July 1998)
* cj-news-0-7::                  Changes in MySQL Connector/J 0.7 (01 July 1998)
* cj-news-0-6::                  Changes in MySQL Connector/J 0.6 (21 May 1998)


File: manual.info,  Node: cj-news-1-2a,  Next: cj-news-1-1i,  Prev: cg-news-1-0,  Up: cg-news-1-0

C.7.7.1 Changes in MySQL Connector/J 1.2a (14 April 1999)
.........................................................

   * Fixed character-set support for non-Javasoft JVMs (thanks to many
     people for pointing it out)

   * Fixed ResultSet.getBoolean() to recognize 'y' & 'n' as well as '1'
     & '0' as boolean flags. (thanks to Tim Pizey)

   * Fixed ResultSet.getTimestamp() to give better performance.
     (thanks to Richard Swift)

   * Fixed getByte() for numeric types. (thanks to Ray Bellis)

   * Fixed DatabaseMetaData.getTypeInfo() for DATE type. (thanks to
     Paul Johnston)

   * Fixed EscapeProcessor for "fn" calls. (thanks to Piyush Shah at
     locomotive.org)

   * Fixed EscapeProcessor to not do extraneous work if there are no
     escape codes. (thanks to Ryan Gustafson)

   * Fixed Driver to parse URLs of the form "jdbc:mysql://host:port"
     (thanks to Richard Lobb)


File: manual.info,  Node: cj-news-1-1i,  Next: cj-news-1-1h,  Prev: cj-news-1-2a,  Up: cg-news-1-0

C.7.7.2 Changes in MySQL Connector/J 1.1i (24 March 1999)
.........................................................

   * Fixed Timestamps for PreparedStatements

   * Fixed null pointer exceptions in RSMD and RS

   * Re-compiled with jikes for valid class files (thanks ms!)


File: manual.info,  Node: cj-news-1-1h,  Next: cj-news-1-1g,  Prev: cj-news-1-1i,  Up: cg-news-1-0

C.7.7.3 Changes in MySQL Connector/J 1.1h (08 March 1999)
.........................................................

   * Fixed escape processor to deal with unmatched { and } (thanks to
     Craig Coles)

   * Fixed escape processor to create more portable (between DATETIME
     and TIMESTAMP types) representations so that it will work with
     BETWEEN clauses. (thanks to Craig Longman)

   * MysqlIO.quit() now closes the socket connection. Before, after
     many failed connections some OS's would run out of file
     descriptors. (thanks to Michael Brinkman)

   * Fixed NullPointerException in Driver.getPropertyInfo.  (thanks to
     Dave Potts)

   * Fixes to MysqlDefs to allow all *text fields to be retrieved as
     Strings. (thanks to Chris at Leverage)

   * Fixed setDouble in PreparedStatement for large numbers to avoid
     sending scientific notation to the database. (thanks to J.S.
     Ferguson)

   * Fixed getScale() and getPrecision() in RSMD. (contrib'd by James
     Klicman)

   * Fixed getObject() when field was DECIMAL or NUMERIC (thanks to
     Bert Hobbs)

   * DBMD.getTables() bombed when passed a null table-name pattern.
     Fixed. (thanks to Richard Lobb)

   * Added check for "client not authorized" errors during connect.
     (thanks to Hannes Wallnoefer)


File: manual.info,  Node: cj-news-1-1g,  Next: cj-news-1-1f,  Prev: cj-news-1-1h,  Up: cg-news-1-0

C.7.7.4 Changes in MySQL Connector/J 1.1g (19 February 1999)
............................................................

   * Result set rows are now byte arrays. Blobs and Unicode work
     bidriectonally now. The useUnicode and encoding options are
     implemented now.

   * Fixes to PreparedStatement to send binary set by setXXXStream to
     be sent untouched to the MySQL server.

   * Fixes to getDriverPropertyInfo().


File: manual.info,  Node: cj-news-1-1f,  Next: cj-news-1-1b,  Prev: cj-news-1-1g,  Up: cg-news-1-0

C.7.7.5 Changes in MySQL Connector/J 1.1f (31 December 1998)
............................................................

   * Changed all ResultSet fields to Strings, this should allow Unicode
     to work, but your JVM must be able to convert between the
     character sets. This should also make reading data from the server
     be a bit quicker, because there is now no conversion from
     StringBuffer to String.

   * Changed PreparedStatement.streamToString() to be more efficient
     (code from Uwe Schaefer).

   * URL parsing is more robust (throws SQL exceptions on errors rather
     than NullPointerExceptions)

   * PreparedStatement now can convert Strings to Time/Date values via
     setObject() (code from Robert Currey).

   * IO no longer hangs in Buffer.readInt(), that bug was introduced in
     1.1d when changing to all byte-arrays for result sets. (Pointed
     out by Samo Login)


File: manual.info,  Node: cj-news-1-1b,  Next: cj-news-1-1,  Prev: cj-news-1-1f,  Up: cg-news-1-0

C.7.7.6 Changes in MySQL Connector/J 1.1b (03 November 1998)
............................................................

   * Fixes to DatabaseMetaData to allow both IBM VA and J-Builder to
     work. Let me know how it goes. (thanks to Jac Kersing)

   * Fix to ResultSet.getBoolean() for NULL strings (thanks to Barry
     Lagerweij)

   * Beginning of code cleanup, and formatting. Getting ready to branch
     this off to a parallel JDBC-2.0 source tree.

   * Added "final" modifier to critical sections in MysqlIO and Buffer
     to allow compiler to inline methods for speed.

9-29-98

   * If object references passed to setXXX() in PreparedStatement are
     null, setNull() is automatically called for you. (Thanks for the
     suggestion goes to Erik Ostrom)

   * setObject() in PreparedStatement will now attempt to write a
     serialized representation of the object to the database for
     objects of Types.OTHER and objects of unknown type.

   * Util now has a static method readObject() which given a ResultSet
     and a column index will re-instantiate an object serialized in the
     above manner.


File: manual.info,  Node: cj-news-1-1,  Next: cj-news-1-0,  Prev: cj-news-1-1b,  Up: cg-news-1-0

C.7.7.7 Changes in MySQL Connector/J 1.1 (02 September 1998)
............................................................

   * Got rid of "ugly hack" in MysqlIO.nextRow(). Rather than catch an
     exception, Buffer.isLastDataPacket() was fixed.

   * Connection.getCatalog() and Connection.setCatalog() should work
     now.

   * Statement.setMaxRows() works, as well as setting by property
     maxRows. Statement.setMaxRows() overrides maxRows set via
     properties or url parameters.

   * Automatic re-connection is available. Because it has to "ping" the
     database before each query, it is turned off by default. To use
     it, pass in "autoReconnect=true" in the connection URL. You may
     also change the number of reconnect tries, and the initial timeout
     value via "maxReconnects=n" (default 3) and "initialTimeout=n"
     (seconds, default 2) parameters. The timeout is an exponential
     backoff type of timeout; for example, if you have initial timeout
     of 2 seconds, and maxReconnects of 3, then the driver will timeout
     2 seconds, 4 seconds, then 16 seconds between each re-connection
     attempt.


File: manual.info,  Node: cj-news-1-0,  Next: cj-news-0-9d,  Prev: cj-news-1-1,  Up: cg-news-1-0

C.7.7.8 Changes in MySQL Connector/J 1.0 (24 August 1998)
.........................................................

   * Fixed handling of blob data in Buffer.java

   * Fixed bug with authentication packet being sized too small.

   * The JDBC Driver is now under the LPGL

8-14-98

   * Fixed Buffer.readLenString() to correctly read data for BLOBS.

   * Fixed PreparedStatement.stringToStream to correctly read data for
     BLOBS.

   * Fixed PreparedStatement.setDate() to not add a day. (above fixes
     thanks to Vincent Partington)

   * Added URL parameter parsing (?user=... and so forth).


File: manual.info,  Node: cj-news-0-9d,  Next: cj-news-0-9,  Prev: cj-news-1-0,  Up: cg-news-1-0

C.7.7.9 Changes in MySQL Connector/J 0.9d (04 August 1998)
..........................................................

   * Big news! New package name. Tim Endres from ICE Engineering is
     starting a new source tree for GNU GPL'd Java software.  He's
     graciously given me the org.gjt.mm package directory to use, so
     now the driver is in the org.gjt.mm.mysql package scheme. I'm
     "legal" now. Look for more information on Tim's project soon.

   * Now using dynamically sized packets to reduce memory usage when
     sending commands to the DB.

   * Small fixes to getTypeInfo() for parameters, and so forth.

   * DatabaseMetaData is now fully implemented. Let me know if these
     drivers work with the various IDEs out there. I've heard that
     they're working with JBuilder right now.

   * Added JavaDoc documentation to the package.

   * Package now available in .zip or .tar.gz.


File: manual.info,  Node: cj-news-0-9,  Next: cj-news-0-8,  Prev: cj-news-0-9d,  Up: cg-news-1-0

C.7.7.10 Changes in MySQL Connector/J 0.9 (28 July 1998)
........................................................

   * Implemented getTypeInfo(). Connection.rollback() now throws an
     SQLException per the JDBC spec.

   * Added PreparedStatement that supports all JDBC API methods for
     PreparedStatement including InputStreams. Please check this out
     and let me know if anything is broken.

   * Fixed a bug in ResultSet that would break some queries that only
     returned 1 row.

   * Fixed bugs in DatabaseMetaData.getTables(),
     DatabaseMetaData.getColumns() and DatabaseMetaData.getCatalogs().

   * Added functionality to Statement that allows executeUpdate() to
     store values for IDs that are automatically generated for
     AUTO_INCREMENT fields. Basically, after an executeUpdate(), look
     at the SQLWarnings for warnings like "LAST_INSERTED_ID = 'some
     number', COMMAND = 'your SQL query'". If you are using
     AUTO_INCREMENT fields in your tables and are executing a lot of
     executeUpdate()s on one Statement, be sure to clearWarnings()
     every so often to save memory.


File: manual.info,  Node: cj-news-0-8,  Next: cj-news-0-7,  Prev: cj-news-0-9,  Up: cg-news-1-0

C.7.7.11 Changes in MySQL Connector/J 0.8 (06 July 1998)
........................................................

   * Split MysqlIO and Buffer to separate classes. Some ClassLoaders
     gave an IllegalAccess error for some fields in those two classes.
     Now mm.mysql works in applets and all classloaders. Thanks to Joe
     Ennis <jce@mail.boone.com> for pointing out the problem and
     working on a fix with me.


File: manual.info,  Node: cj-news-0-7,  Next: cj-news-0-6,  Prev: cj-news-0-8,  Up: cg-news-1-0

C.7.7.12 Changes in MySQL Connector/J 0.7 (01 July 1998)
........................................................

   * Fixed DatabaseMetadata problems in getColumns() and bug in switch
     statement in the Field constructor. Thanks to Costin Manolache
     <costin@tdiinc.com> for pointing these out.


File: manual.info,  Node: cj-news-0-6,  Prev: cj-news-0-7,  Up: cg-news-1-0

C.7.7.13 Changes in MySQL Connector/J 0.6 (21 May 1998)
.......................................................

   * Incorporated efficiency changes from Richard Swift
     <Richard.Swift@kanatek.ca> in `MysqlIO.java' and `ResultSet.java':

   * We're now 15% faster than gwe's driver.

   * Started working on `DatabaseMetaData'.

   * The following methods are implemented:

        * `getTables()'

        * `getTableTypes()'

        * `getColumns()'

        * `getCatalogs()'


File: manual.info,  Node: news-connector-mxj,  Next: ccpp-news,  Prev: cj-news,  Up: news

C.8 MySQL Connector/MXJ Change History
======================================

* Menu:

* news-connector-mxj-5-0-6::     Changes in MySQL Connector/MXJ 5.0.6 (04 May 2007)
* news-connector-mxj-5-0-5::     Changes in MySQL Connector/MXJ 5.0.5 (14 March 2007)
* news-connector-mxj-5-0-4::     Changes in MySQL Connector/MXJ 5.0.4 (28 January 2007)
* news-connector-mxj-5-0-3::     Changes in MySQL Connector/MXJ 5.0.3 (24 June 2006)
* news-connector-mxj-5-0-2::     Changes in MySQL Connector/MXJ 5.0.2 (15 June 2006)
* news-connector-mxj-5-0-1::     Changes in MySQL Connector/MXJ 5.0.1 (Never released)
* news-connector-mxj-5-0-0::     Changes in MySQL Connector/MXJ 5.0.0 (09 December 2005)


File: manual.info,  Node: news-connector-mxj-5-0-6,  Next: news-connector-mxj-5-0-5,  Prev: news-connector-mxj,  Up: news-connector-mxj

C.8.1 Changes in MySQL Connector/MXJ 5.0.6 (04 May 2007)
--------------------------------------------------------

Functionality added or changed:

   * Updated internal jar file names to include version information and
     be more consistent with Connector/J jar naming. For example,
     `connector-mxj.jar' is now
     `mysql-connector-mxj-${mxj-version}.jar'.

   * Updated commercial license files.

   * Added copyright notices to some classes which were missing them.

   * Added InitializeUser and QueryUtil classes to support new feature.

   * Added new tests for initial-user & expanded some existing tests.

   * ConnectorMXJUrlTestExample and ConnectorMXJObjectTestExample now
     demonstrate the initialization of user/password and creating the
     initial database (rather than using "test").

   * Added new connection property `initialize-user' which, if set to
     `true' will remove the default, un-passworded anonymous and root
     users, and create the user/password from the connection url.

   * Removed obsolete field `SimpleMysqldDynamicMBean.lastInvocation'.

   * Clarified code in `DefaultsMap.entrySet()'.

   * Removed obsolete `PatchedStandardSocketFactory' java file.

   * Added `main(String[])' to
     `com/mysql/management/AllTestsSuite.java'.

   * Errors reading `portFile' are now reported using
     `stacktrace(err)', previously `System.err' was used.

   * `portFile' now contains a new-line to be consistent with `pidFile'.

   * Fixed where versionString.trim() was ignored.

   * Removed references to File.deleteOnExit, a warning is printed
     instead.

Bugs fixed:

   * Changed tests to shutdown mysqld prior to deleting files.

   * Fixed port file to always be writen to datadir.

   * Added os.name-os.arch to resource directory mapping properties
     file.

   * Swapped out commercial binaries for v5.0.40.

   * Delete `portFile' on shutdown.

   * Moved `platform-map.properties' into `db-files.jar'.

   * Clarified the startup max wait numbers.

   * Updated `build.xml' in preperation for next beta build.

   * Removed `use-default-architecture' property replaced.

   * Added null-check to deal with C/MXJ being loaded by the bootstrap
     classloaders with JVMs for which `getClassLoader()' returns null.

   * Added robustness around reading portfile.

   * Removed `PatchedStandardSocketFactory' (fixed in Connetor/J 5.0.6).

   * Refactored duplication from tests and examples to QueryUtil.

   * Removed obsolete InitializePasswordExample


File: manual.info,  Node: news-connector-mxj-5-0-5,  Next: news-connector-mxj-5-0-4,  Prev: news-connector-mxj-5-0-6,  Up: news-connector-mxj

C.8.2 Changes in MySQL Connector/MXJ 5.0.5 (14 March 2007)
----------------------------------------------------------

Bugs fixed:

   * Moved `MysqldFactory' to main package.

   * Reformatting: Added newlines some files which did not end in them.

   * Swapped out commercial binaries for v5.0.36.

   * Found and removed dynamic linking in mysql_kill; updated solution.

   * Changed protected constructor of `SimpleMysqldDynamicMBean' from
     taking a `MysqldResource' to taking a `MysqldFactory', in order to
     lay groundwork for addressing BUG discovered by Andrew Rubinger.
     See: 143046#msg-143046MySQL Forums (Actual testing with JBoss, and
     filing a bug, is still required.)

   * `build.xml': `usage' now slightly more verbose; some reformatting.

   * Now incoporates Reggie Bernett's `SafeTerminateProcess' and only
     calls the unsafe TerminateProcess as a final last resort.

   * New windows `kill.exe' fixes bug where mysqld was being force
     terminated. Issue reported by bruno haleblian and others, see:
     140623#msg-140623MySQL Forums.

   * Replaced `Boolean.parseBoolean' with JDK 1.4 compliant `valueOf'.

   * Changed `connector-mxj.properties' default mysql version to 5.0.37.

   * In testing so far mysqld reliably shuts down cleanly much faster.

   * Added testcase to `com.mysql.management.jmx.AcceptanceTest' which
     demonstrats that `dataDir' is a mutable MBean property.

   * Updated `build.xml' in prep for next release.

   * Changed `SimpleMysqldDynamicMBean' to create `MysqldResource' on
     demand in order to allow setting of `datadir'. (Rubinger bug
     groundwork).

   * Clarified the synchronization of `MysqldResource' methods.

   * `SIGHUP' is replaced with `MySQLShutdown<PID>' event.

   * Clarified the immutability of `baseDir', `dataDir', `pidFile',
     `portFile'.

   * Added 5.1.15 binaries to the repository.

   * Removed 5.1.14 binaries from the repository.

   * Added `getDataDir()' to interface `MysqldResourceI'.

   * Added 5.1.14 binaries to repository.

   * Replaced windows *Note `kill.exe': kill. resource with re-written
     version specific to mysqld.

   * Added Patched `StandardSocketFactory' from Connector/J 5-0 HEAD.

   * Ensured 5.1.14 compatibility.

   * Swapped out gpl binaries for v5.0.37.

   * Removed 5.0.22 binaries from the repository.


File: manual.info,  Node: news-connector-mxj-5-0-4,  Next: news-connector-mxj-5-0-3,  Prev: news-connector-mxj-5-0-5,  Up: news-connector-mxj

C.8.3 Changes in MySQL Connector/MXJ 5.0.4 (28 January 2007)
------------------------------------------------------------

Bugs fixed:

   * Allow multiple calls to start server from URL connection on
     non-3306 port.  (Bug#24004 (http://bugs.mysql.com/24004))

   * Updated `build.xml' to build to handle with different gpl and
     commercial mysld version numbers.

   * Only populate the options map from the help text if specifically
     requested or in the MBean case.

   * Introduced property for Linux & WinXX to default to 32bit versions.

   * Swapped out gpl binaries for v5.0.27.

   * Swapped out commercial binaries for v5.0.32.

   * Moved mysqld binary resourced into separate jar file NOTICE:
     `CLASSPATH' will now need to `connector-mxj-db-files.jar'.

   * Minor test robustness improvements.

   * Moved default version string out of java class into a text
     editable properties file (`connector-mxj.properties') in the
     resources directory.

   * Fixed test to be tollerant of `/tmp' being a symlink to `/foo/tmp'.


File: manual.info,  Node: news-connector-mxj-5-0-3,  Next: news-connector-mxj-5-0-2,  Prev: news-connector-mxj-5-0-4,  Up: news-connector-mxj

C.8.4 Changes in MySQL Connector/MXJ 5.0.3 (24 June 2006)
---------------------------------------------------------

Bugs fixed:

   * Removed unused imports, formatted code, made minor edits to tests.

   * Removed "TeeOutputStream" - no longer needed.

   * Swapped out the mysqld binaries for MySQL v5.0.22.


File: manual.info,  Node: news-connector-mxj-5-0-2,  Next: news-connector-mxj-5-0-1,  Prev: news-connector-mxj-5-0-3,  Up: news-connector-mxj

C.8.5 Changes in MySQL Connector/MXJ 5.0.2 (15 June 2006)
---------------------------------------------------------

Bugs fixed:

   * Replaced string parsing with JDBC connection attempt for
     determining if a mysqld is "ready for connections" `CLASSPATH'
     will now need to include Connector/J jar.

   * "platform" directories replace spaces with underscores

   * extracted array and list printing to ListToString utility class

   * Swapped out the mysqld binaries for MySQL v5.0.21

   * Added trace level logging with Aspect/J.  `CLASSPATH' will now
     need to include `lib/aspectjrt.jar'

   * reformatted code

   * altered to be "basedir" rather than "port" oriented.

   * help parsing test reflects current help options

   * insulated users from problems with "." in basedir

   * swapped out the mysqld binaries for MySQL v5.0.18

   * Made tests more robust be deleting the /tmp/test-c.mxj directory
     before running tests.

   * ServerLauncherSocketFactory.shutdown API change: now takes File
     parameter (basedir) instead of port.

   * socket is now "mysql.sock" in datadir

   * added ability to specify "mysql-version" as an url parameter

   * Extended timeout for help string parsing, to avoid cases where the
     help text was getting prematurely flushed, and thus truncated.

   * swapped out the mysqld binaries for MySQL v5.0.19

   * MysqldResource now tied to dataDir as well as basedir (API CHANGE)

   * moved PID file into datadir

   * ServerLauncherSocketFactory.shutdown now works across JVMs.

   * extracted splitLines(String) to Str utility class

   * ServerLauncherSocketFactory.shutdown(port) no longer throws, only
     reports to System.err

   * ServerLauncherSocketFactory now treats URL parameters in the form
     of `&server.foo=null' as `serverOptionMap.put("foo", null)'

   * ServerLauncherSocketFactory.shutdown API change: now takes 2 File
     parameters (basedir, datadir)


File: manual.info,  Node: news-connector-mxj-5-0-1,  Next: news-connector-mxj-5-0-0,  Prev: news-connector-mxj-5-0-2,  Up: news-connector-mxj

C.8.6 Changes in MySQL Connector/MXJ 5.0.1 (Never released)
-----------------------------------------------------------

This was an internal only release.


File: manual.info,  Node: news-connector-mxj-5-0-0,  Prev: news-connector-mxj-5-0-1,  Up: news-connector-mxj

C.8.7 Changes in MySQL Connector/MXJ 5.0.0 (09 December 2005)
-------------------------------------------------------------

Bugs fixed:

   * Removed HelpOptionsParser's need to reference a MysqldResource.

   * Reorganized utils into a single "Utils" collaborator.

   * Minor test tweaks

   * Altered examples and tests to use new Connector/J 5.0 URL syntax
     for for launching Connector/MXJ ("jdbc:mysql:mxj://")

   * Swapped out the mysqld binaries for MySQL v5.0.16.

   * Ditched "ClassUtil" (merged with Str).

   * Minor refactorings for type casting and exception handling.


File: manual.info,  Node: ccpp-news,  Next: mysql-proxy-news,  Prev: news-connector-mxj,  Up: news

C.9 MySQL Connector/C++ Change History
======================================

* Menu:

* ccpp-news-1-0::                Changes in MySQL Connector/C++ 1.0.x


File: manual.info,  Node: ccpp-news-1-0,  Prev: ccpp-news,  Up: ccpp-news

C.9.1 Changes in MySQL Connector/C++ 1.0.x
------------------------------------------

* Menu:

* ccpp-news-1-0-5::              Changes in MySQL Connector/CPP 1.0.5 (21 April 2009)
* ccpp-news-1-0-4::              Changes in MySQL Connector/CPP 1.0.4 (31 March 2009 beta)
* ccpp-news-1-0-3::              Changes in MySQL Connector/CPP 1.0.3 (02 March 2009 alpha)
* ccpp-news-1-0-2::              Changes in MySQL Connector/CPP 1.0.2 (19 December 2008 alpha)
* ccpp-news-1-0-1::              Changes in MySQL Connector/CPP 1.0.1 (01 December 2008 alpha)


File: manual.info,  Node: ccpp-news-1-0-5,  Next: ccpp-news-1-0-4,  Prev: ccpp-news-1-0,  Up: ccpp-news-1-0

C.9.1.1 Changes in MySQL Connector/CPP 1.0.5 (21 April 2009)
............................................................

This is the first Generally Available (GA) release.

Functionality added or changed:

   * The interface of `sql::ConnectionMetaData',
     `sql::ResultSetMetaData' and `sql::ParameterMetaData' was modified
     to have a protected destructor. As a result the client code has no
     need to destruct the metadata objects returned by the connector.
     MySQL Connector/C++ handles the required destruction. This enables
     statements such as:

          connection->getMetaData->getSchema();

     This avoids potential memory leaks that could occur as a result of
     losing the pointer returned by `getMetaData()'.

   * Improved memory management. Potential memory leak situations are
     handled more robustly.

   * Changed the interface of `sql::Driver' and `sql::Connection' so
     they accept the options map by alias instead of by value.

   * Changed the return type of `sql::SQLException::getSQLState()' from
     `std::string' to `const char *' to be consistent with
     `std::exception::what()'.

   * Implemented `getResultSetType()' and `setResultSetType()' for
     `Statement'. Uses `TYPE_FORWARD_ONLY', which means unbuffered
     result set and `TYPE_SCROLL_INSENSITIVE', which means buffered
     result set.

   * Implemented `getResultSetType()' for `PreparedStatement'. The
     setter is not implemented because currently `PreparedStatement'
     cannot do refetching.  Storing the result means the bind buffers
     will be correct.

   * Added the option `defaultStatementResultType' to
     `MySQL_Connection::setClientOption()'. Also, the method now
     returns `sql::Connection *'.

   * Added `Result::getType()'. Implemented for the three result set
     classes.

   * Enabled tracing functionality when building with Microsoft Visual
     C++ 8 and later, which corresponds to Microsoft Visual Studio 2005
     and later.

   * Added better support for named pipes, on Windows. Use `pipe://'
     and add the path to the pipe. Shared memory connections are
     currently not supported.

Bugs fixed:

   * A bug was fixed in `MySQL_Connection::setSessionVariable()', which
     had been causing exceptions to be thrown.


File: manual.info,  Node: ccpp-news-1-0-4,  Next: ccpp-news-1-0-3,  Prev: ccpp-news-1-0-5,  Up: ccpp-news-1-0

C.9.1.2 Changes in MySQL Connector/CPP 1.0.4 (31 March 2009 beta)
.................................................................

Functionality added or changed:

   * An installer was added for the Windows operating system.

   * Minimum CMake version required was changed from 2.4.2 to 2.6.2.
     The latest version is required for building on Windows.

   * `metadataUseInfoSchema' was added to the connection property map,
     which allows control of the `INFORMATION_SCHEMA' for meta data.

   * Implemented `MySQL_ConnectionMetaData::supportsConvert(from, to)'.

   * Added support for MySQL Connector/C.

Bugs fixed:

   * A bug was fixed in all implementations of `ResultSet::relative()'
     which was giving a wrong return value although positioning was
     working correctly.

   * A leak was fixed in `MySQL_PreparedResultSet', which occurred when
     the result contained a `BLOB' column.


File: manual.info,  Node: ccpp-news-1-0-3,  Next: ccpp-news-1-0-2,  Prev: ccpp-news-1-0-4,  Up: ccpp-news-1-0

C.9.1.3 Changes in MySQL Connector/CPP 1.0.3 (02 March 2009 alpha)
..................................................................

Functionality added or changed:

   * Added new tests in `test/unit/classes'. Those tests are mostly
     about code coverage. Most of the actual functionality of the
     driver is tested by the tests found in `test/CJUnitPort'.

   * New data types added to the list returned by
     `DatabaseMetaData::getTypeInfo()' are `FLOAT UNSIGED', `DECIMAL
     UNSIGNED', `DOUBLE UNSIGNED'. Those tests may not be in the JDBC
     specification. However, due to the change you should be able to
     look up every type and type name returned by, for example,
     `ResultSetMetaData::getColumnTypeName()'.

   * `MySQL_Driver::getPatchVersion' introduced.

   * Major performance improvements due to new buffered `ResultSet'
     implementation.

   * Addition of `test/unit/README' with instructions for writing bug
     and regression tests.

   * Experimental support for STLPort. This feature may be removed
     again at any time later without prior warning! Type `cmake `-L''
     for configuration instructions.

   * Added properties enabled methods for connecting, which add many
     connect options. This uses a dictionary (map) of key value pairs.
     Methods added are `Driver::connect(map)', and
     `Connection::Connection(map)'.

   * New BLOB implementation. ` sql::Blob' was removed in favor of
     `std::istream'. C++'s `IOStream' library is very powerful, similar
     to PHP's streams. It makes no sense to reinvent the wheel. For
     example, you can pass a `std::istringstream' object to `setBlob()'
     if the data is in memory, or just open a file `std::fstream' and
     let it stream to the DB, or write its own stream. This is also
     true for `getBlob()' where you can just copy data (if a buffered
     result set), or stream data (if implemented).

   * Implemented `ResultSet::getBlob()' which returns `std::stream'.

   * Fixed `MySQL_DatabaseMetaData::getTablePrivileges()'.  Test cases
     were added in the first unit testing framework.

   * Implemented `MySQL_Connection::setSessionVariable()' for setting
     variables like `sql_mode'.

   * Implemented `MySQL_DatabaseMetaData::getColumnPrivileges()'.

   * `cppconn/datatype.h' has changed and is now used again.
     Reimplemented the type subsystem to be more usable - more types
     for binary and non-binary strings.

   * Implementation for `MySQL_DatabaseMetaData::getImportedKeys()' for
     MySQL versions before 5.1.16 using `SHOW', and above using
     `INFORMATION_SCHEMA'.

   * Implemented `MySQL_ConnectionMetaData::getProcedureColumns()'.

   * `make package_source' now packs with bzip2.

   * Re-added `getTypeInfo()' with information about all types
     supported by MySQL and the `sql::DataType'.

   * Changed the implementation of `MySQL_ConstructedResultSet' to use
     the more efficient O(1) access method. This should improve the
     speed with which the metadata result sets are used. Also, there is
     less copying during the construction of the result set, which means
     that all result sets returned from the meta data functions will be
     faster.

   * Introduced, internally, `sql::mysql::MyVal' which has implicit
     constructors. Used in `mysql_metadata.cpp' to create result sets
     with native data instead of always string (varchar).

   * Renamed `ResultSet::getLong()' to `ResultSet::getInt64()'.
     `resultset.h' includes typdefs for Windows to be able to use
     `int64_t'.

   * Introduced `ResultSet::getUInt()' and `ResultSet::getUInt64()'.

   * Improved the implementation for `ResultSetMetaData::isReadOnly()'.
     Values generated from views are read-only. These generated values
     don't have `db' in `MYSQL_FIELD' set, while all normal columns do
     have.

   * Implemented `MySQL_DatabaseMetaData::getExportedKeys()'.

   * Implemented `MySQL_DatabaseMetaData::getCrossReference()'.

Bugs fixed:

   * Bug fixed in `MySQL_PreparedResultSet::getString()'.  Returned
     string that had real data but the length was random.  Now, the
     string is initialized with the correct length and thus is binary
     safe.

   * Corrected handling of unsigned server types. Now returning correct
     values.

   * Fixed handling of numeric columns in
     `ResultSetMetaData::isCaseSensitive' to return `false'.


File: manual.info,  Node: ccpp-news-1-0-2,  Next: ccpp-news-1-0-1,  Prev: ccpp-news-1-0-3,  Up: ccpp-news-1-0

C.9.1.4 Changes in MySQL Connector/CPP 1.0.2 (19 December 2008 alpha)
.....................................................................

Functionality added or changed:

   * Implemented `getScale()', `getPrecision()' and
     `getColumnDisplaySize()' for `MySQL_ResultSetMetaData' and
     `MySQL_Prepared_ResultSetMetaData'.

   * Changed `ResultSetMetaData' methods `getColumnDisplaySize()',
     `getPrecision()', `getScale()' to return `unsigned int' instead of
     `signed int'.

   * `DATE', `DATETIME' and `TIME' are now being handled when calling
     the `MySQL_PreparedResultSet' methods `getString()', `getDouble()',
     `getInt()', `getLong()', `getBoolean()'.

   * Reverted implementation of
     `MySQL_DatabaseMetaData::getTypeInfo()'. Now unimplemented. In
     addition, removed `cppconn/datatype.h' for now, until a more
     robust implementation of the types can be developed.

   * Implemented `MySQL_PreparedStatement::setNull()'.

   * Implemented `MySQL_PreparedStatement::clearParameters()'.

   * Added PHP script `examples/cpp_trace_analyzer.php' to filter the
     output of the debug trace. Please see the inline comments for
     documentation. This script is unsupported.

   * Implemented `MySQL_ResultSetMetaData::getPrecision()' and
     `MySQL_Prepared_ResultSetMetaData::getPrecision()', updating
     example.

   * Added new unit test framework for JDBC compliance and regression
     testing.

   * Added `test/unit' as a basis for general unit tests using the new
     test framework, see `test/unit/example' for basic usage examples.

Bugs fixed:

   * Fixed `MySQL_PreparedStatementResultSet::getDouble()' to return
     the correct value when the underlying type is `MYSQL_TYPE_FLOAT'.

   * Fixed bug in `MySQL_ConnectionMetaData::getIndexInfo()'. The
     method did not work because the schema name wasn't included in the
     query sent to the server.

   * Fixed a bug in `MySQL_ConnectionMetaData::getColumns()' which was
     performing a cartesian product of the columns in the table times
     the columns matching `columnNamePattern'.  The example
     `example/connection_meta_schemaobj.cpp' was extended to cover the
     function.

   * Fixed bugs in `MySQL_DatabaseMetaData'. All `supportsCatalogXXXXX'
     methods were incorrectly returning `true' and all
     `supportsSchemaXXXX' methods were incorrectly returning `false'.
     Now `supportsCatalogXXXXX' returns `false' and
     `supportsSchemaXXXXX' returns `true'.

   * Fixed bugs in the `MySQL_PreparedStatements' methods `setBigInt()'
     and `setDatetime()'. They decremented the internal column index
     before forwarding the request. This resulted in a double-decrement
     and therefore the wrong internal column index.  The error message
     generated was:

          setString() ... invalid "parameterIndex"

   * Fixed a bug in `getString()'.  `getString()' is now binary safe. A
     new example was also added.

   * Fixed bug in `FLOAT' handling.

   * Fixed `MySQL_PreparedStatement::setBlob()'. In the tests there is
     a simple example of a class implementing `sql::Blob'.


File: manual.info,  Node: ccpp-news-1-0-1,  Prev: ccpp-news-1-0-2,  Up: ccpp-news-1-0

C.9.1.5 Changes in MySQL Connector/CPP 1.0.1 (01 December 2008 alpha)
.....................................................................

Functionality added or changed:

   * `sql::mysql::MySQL_SQLException' was removed.  The distinction
     between server and client (connector) errors, based on the type of
     the exception, has been removed. However, the error code can still
     be checked in order to evaluate the error type.

   * Support for (n)make install was added. You can change the default
     installation path. Carefully read the messages displayed after
     executing cmake. The following are installed:

        * Static and the dynamic version of the library,
          `libmysqlcppconn'.

        * Generic interface, `cppconn'.

        * Two MySQL specific headers:

          `mysql_driver.h', use this if you want to get your
          connections from the driver instead of instantiating a
          `MySQL_Connection' object.  This makes your code portable
          when using the common interface.

          `mysql_connection.h', use this if you intend to link directly
          to the `MySQL_Connection' class and use its specifics not
          found in `sql::Connection'.

          However, you can make your application fully abstract by
          using the generic interface rather than these two headers.

   * Driver Manager was removed.

   * Added `ConnectionMetaData::getSchemas()' and
     `Connection::setSchema()'.

   * `ConnectionMetaData::getCatalogTerm()' returns not applicable,
     there is no counterpart to catalog in MySQL Connector/C++.

   * Added experimental GCov support, `cmake
     `-DMYSQLCPPCONN_GCOV_ENABLE:BOOL=1''

   * All examples can be given optional connection parameters on the
     command line, for example:

          examples/connect tcp://host:port user pass database

     or

          examples/connect unix:///path/to/mysql.sock user pass database

   * Renamed `ConnectionMetaData::getTables: TABLE_COMMENT' to
     `REMARKS'.

   * Renamed `ConnectionMetaData::getProcedures: PROCEDURE_SCHEMA' to
     `PROCEDURE_SCHEM'.

   * Renamed `ConnectionMetaData::getPrimaryKeys(): COLUMN' to
     `COLUMN_NAME', `SEQUENCE' to `KEY_SEQ', and `INDEX_NAME' to
     `PK_NAME'.

   * Renamed `ConnectionMetaData::getImportedKeys(): PKTABLE_CATALOG'
     to `PKTABLE_CAT', `PKTABLE_SCHEMA' to `PKTABLE_SCHEM',
     `FKTABLE_CATALOG' to `FKTABLE_CAT', `FKTABLE_SCHEMA' to
     `FKTABLE_SCHEM'.

   * Changed metadata column name `TABLE_CATALOG' to `TABLE_CAT' and
     `TABLE_SCHEMA' to `TABLE_SCHEM' to ensure JDBC compliance.

   * Introduced experimental CPack support, see make help.

   * All tests changed to create TAP compliant output.

   * Renamed `sql::DbcMethodNotImplemented' to
     `sql::MethodNotImplementedException'

   * Renamed `sql::DbcInvalidArgument' to
     `sql::InvalidArgumentException'

   * Changed `sql::DbcException' to implement the interface of JDBC's
     `SQLException'. Renamed to `sql::SQLException'.

   * Converted Connector/J tests added.

   * MySQL Workbench 5.1 changed to use MySQL Connector/C++ for its
     database connectivity.

   * New directory layout.


File: manual.info,  Node: mysql-proxy-news,  Prev: ccpp-news,  Up: news

C.10 MySQL Proxy Change History
===============================

* Menu:

* mysql-proxy-news-0-7-0::       Changes in MySQL Proxy 0.7.0 (Not yet released)
* mysql-proxy-news-0-6-1::       Changes in MySQL Proxy 0.6.1 (06 February 2008)
* mysql-proxy-news-0-6-0::       Changes in MySQL Proxy 0.6.0 (11 September 2007)
* mysql-proxy-news-0-5-1::       Changes in MySQL Proxy 0.5.1 (30 June 2007)
* mysql-proxy-news-0-5-0::       Changes in MySQL Proxy 0.5.0 (19 June 2007)


File: manual.info,  Node: mysql-proxy-news-0-7-0,  Next: mysql-proxy-news-0-6-1,  Prev: mysql-proxy-news,  Up: mysql-proxy-news

C.10.1 Changes in MySQL Proxy 0.7.0 (Not yet released)
------------------------------------------------------

Bugs fixed:

   * *Security Enhancement*: Accessing *Note `mysql-proxy':
     mysql-proxy. using a client or backend with a MySQL protocol less
     than MySQL 5.0 would result in *Note `mysql-proxy': mysql-proxy.
     aborting with an assertion.  This is because *Note `mysql-proxy':
     mysql-proxy. only supports MySQL Protocol 5.0 or higher. The proxy
     will now report a fault.  (Bug#31419 (http://bugs.mysql.com/31419))

   * Using *Note `mysql-proxy': mysql-proxy. with very large return
     datasets from queries, with or without manipulate of the dataset
     within the Lua engine could cause a crash.  (Bug#39332
     (http://bugs.mysql.com/39332))

   * When using *Note `mysql-proxy': mysql-proxy. in a master-master
     replication scenario, a failure in one of the replication masters
     would fail to be identified by the proxy and connections would not
     be redirected to the other master.  (Bug#35295
     (http://bugs.mysql.com/35295))


File: manual.info,  Node: mysql-proxy-news-0-6-1,  Next: mysql-proxy-news-0-6-0,  Prev: mysql-proxy-news-0-7-0,  Up: mysql-proxy-news

C.10.2 Changes in MySQL Proxy 0.6.1 (06 February 2008)
------------------------------------------------------

Functionality added or changed:

   * Fixed assertions on write-errors

   * Fixed sending fake server-greetings in `connect_server()'.

   * Fixed error handling for socket functions on Windows.

   * Added new features to `run-tests.lua'.


File: manual.info,  Node: mysql-proxy-news-0-6-0,  Next: mysql-proxy-news-0-5-1,  Prev: mysql-proxy-news-0-6-1,  Up: mysql-proxy-news

C.10.3 Changes in MySQL Proxy 0.6.0 (11 September 2007)
-------------------------------------------------------

Functionality added or changed:

   * When using read/write splitting and the `rw-splitting.lua' example
     script, connecting a second user to the proxy returns an error
     message.  (Bug#30867 (http://bugs.mysql.com/30867))

   * Added support in `read_query_result()' to overwrite the result-set.

   * Added `--no-daemon' and `--pid-file'.

   * Added hooks for `read_auth()', `read_handshake()' and
     `read_auth_result()'.

   * Added handling of `proxy.connection.backend_ndx' in
     `connect_server()' and `read_query()' to support read/write
     splitting.

   * Added support for `proxy.response.packets'.

   * Added testcases.

   * Added `--no-proxy' to disable the proxy.

   * Added support for listening UNIX sockets.

   * Added a global lua-scope `proxy.global.*'.

   * Added connection pooling.

Bugs fixed:

   * Fixed assertion on `COM_BINLOG_DUMP'.  (Bug#29764
     (http://bugs.mysql.com/29764))

   * Fixed assertion on result-packets like `[ field-len | fields | EOF
     | ERR ]'.  (Bug#29732 (http://bugs.mysql.com/29732))

   * Fixed assertion at login with empty password + empty default db.
     (Bug#29719 (http://bugs.mysql.com/29719))

   * Fixed assertion at `COM_SHUTDOWN'.  (Bug#29719
     (http://bugs.mysql.com/29719))

   * Fixed crash if `proxy.connection' is used in `connect_server()'.

   * Fixed check for `glib2' to require at least 2.6.0.

   * Fixed assertion when all backends are down and we try to connect.

   * Fixed connection-stalling if `read_query_result()' throws an
     `assert()'ion.

   * Fixed len-encoding on `proxy.resulsets'.

   * Fixed compilation on win32.

   * Fixed assertion when connecting to the MySQL 6.0.1.

   * Fixed decoding of len-encoded ints for 3-byte notation.

   * Fixed `inj.resultset.affected_rows' on *Note `SELECT': select.
     queries.

   * Fixed handling of (SQL) `NULL' in result-sets.

   * Fixed mem-leak with `proxy.response.*' is used.


File: manual.info,  Node: mysql-proxy-news-0-5-1,  Next: mysql-proxy-news-0-5-0,  Prev: mysql-proxy-news-0-6-0,  Up: mysql-proxy-news

C.10.4 Changes in MySQL Proxy 0.5.1 (30 June 2007)
--------------------------------------------------

Functionality added or changed:

   * Added `resultset.affected_rows' and `resultset.insert_id'.

   * Changed `--proxy.profiling' to `--proxy-skip-profiling'.

   * Added missing dependency to `libmysqlclient-dev' to the INSTALL
     file.

   * Added `inj.query_time' and `inj.response_time' into the lua
     scripts.

   * Added support for pre-4.1 passwords in a 4.1 connection.

   * Added script examples for rewriting and injection.

   * Added `proxy.VERSION'.

   * Added support for UNIX sockets.

   * Added protection against duplicate resultsets from a script.

Bugs fixed:

   * Fixed mysql check in configure to die when mysql.h isn't detected.

   * Fixed handling of duplicate ERR on `COM_CHANGE_USER' in MySQL
     5.1.18+.

   * Fixed compile error with MySQL 4.1.x on missing COM_STMT_*.

   * Fixed crash on fields > 250 bytes when the resultset is inspected.

   * Fixed warning if `connect_server()' is not provided.

   * Fixed assertion when a error occurs at initial script exec time.

   * Fixed assertion when `read_query_result()' is not provided when
     `PROXY_SEND_QUERY' is used.


File: manual.info,  Node: mysql-proxy-news-0-5-0,  Prev: mysql-proxy-news-0-5-1,  Up: mysql-proxy-news

C.10.5 Changes in MySQL Proxy 0.5.0 (19 June 2007)
--------------------------------------------------

This is the first beta release.

Bugs fixed:

   * Added `automake'/`autoconf' support.

   * Added `cmake' support.


File: manual.info,  Node: restrictions,  Prev: news,  Up: Top

Appendix D Restrictions and Limits
**********************************

* Menu:

* stored-program-restrictions::  Restrictions on Stored Routines, Triggers, and Events
* signal-restrictions::          Restrictions on Signals
* cursor-restrictions::          Restrictions on Server-Side Cursors
* subquery-restrictions::        Restrictions on Subqueries
* view-restrictions::            Restrictions on Views
* xa-restrictions::              Restrictions on XA Transactions
* charset-restrictions::         Restrictions on Character Sets
* backup-database-restore-restrictions::  Restrictions on `BACKUP DATABASE' and `RESTORE'
* limits::                       Limits in MySQL

The discussion here describes restrictions that apply to the use of
MySQL features such as subqueries or views.


File: manual.info,  Node: stored-program-restrictions,  Next: signal-restrictions,  Prev: restrictions,  Up: restrictions

D.1 Restrictions on Stored Routines, Triggers, and Events
=========================================================

Some of the restrictions noted here apply to all stored routines; that
is, both to stored procedures and stored functions. Some of these
restrictions apply to stored functions but not to stored procedures.

The restrictions for stored functions also apply to triggers.  There
are also some restrictions specific to triggers.

The restrictions for stored procedures also apply to the *Note `DO':
do. clause of Event Scheduler event definitions. There are also some
restrictions specific to events.

Stored routines cannot contain arbitrary SQL statements. The following
statements are disallowed:

   * The locking statements *Note `LOCK TABLES': lock-tables. and *Note
     `UNLOCK TABLES': lock-tables.

   * *Note `ALTER VIEW': alter-view.

   * *Note `LOAD DATA': load-data. and `LOAD TABLE'.

   * *Note `BACKUP DATABASE': backup-database. and *Note `RESTORE':
     restore.

   * SQL prepared statements (*Note `PREPARE': prepare, *Note
     `EXECUTE': execute, *Note `DEALLOCATE PREPARE':
     deallocate-prepare.) can be used in stored procedures, but not
     stored functions or triggers.  Implication: You cannot use dynamic
     SQL within stored functions or triggers (where you construct
     dynamically statements as strings and then execute them).

     In addition, SQL statements that are not permitted within prepared
     statements are also not permitted in stored routines.  See *Note
     sql-syntax-prepared-statements::, for a list of statements
     supported as prepared statements.  Statements not listed there are
     not supported for SQL prepared statements and thus are also not
     supported for stored routines unless noted otherwise in *Note
     stored-routines::.

   * Inserts cannot be delayed. *Note `INSERT DELAYED': insert-delayed.
     syntax is accepted but the statement is handled as a normal *Note
     `INSERT': insert.

For stored functions (but not stored procedures), the following
additional statements or operations are disallowed:

   * Statements that perform explicit or implicit commit or rollback.
     Support for these statements is not required by the SQL standard,
     which states that each DBMS vendor may decide whether to allow
     them.

   * Statements that return a result set. This includes *Note `SELECT':
     select. statements that do not have an `INTO VAR_LIST' clause and
     other statements such as *Note `SHOW': show, *Note `EXPLAIN':
     explain, and *Note `CHECK TABLE': check-table. A function can
     process a result set either with `SELECT ... INTO VAR_LIST' or by
     using a cursor and *Note `FETCH': fetch. statements.  See *Note
     select-into-statement::.

   * *Note `FLUSH': flush. statements.

   * Stored functions cannot be used recursively.

   * Within a stored function or trigger, it is not permitted to modify
     a table that is already being used (for reading or writing) by the
     statement that invoked the function or trigger.

   * If you refer to a temporary table multiple times in a stored
     function under different aliases, a `Can't reopen table:
     'TBL_NAME`''' error occurs, even if the references occur in
     different statements within the function.

   * A stored function acquires table locks before executing, to avoid
     inconsistency in the binary log due to mismatch of the order in
     which statements execute and when they appear in the log. When
     statement-based binary logging is used, statements that invoke a
     function are recorded rather than the statements executed within
     the function. Consequently, stored functions that update the same
     underlying tables do not execute in parallel. In contrast, stored
     procedures do not acquire table-level locks. All statements
     executed within stored procedures are written to the binary log
     even for statement-based binary logging. See *Note
     stored-programs-logging::.

Although some restrictions normally apply to stored functions and
triggers but not to stored procedures, those restrictions do apply to
stored procedures if they are invoked from within a stored function or
trigger. For example, if you use *Note `FLUSH': flush. in a stored
procedure, that stored procedure cannot be called from a stored
function or trigger.

It is possible for the same identifier to be used for a routine
parameter, a local variable, and a table column. Also, the same local
variable name can be used in nested blocks. For example:

     CREATE PROCEDURE p (i INT)
     BEGIN
       DECLARE i INT DEFAULT 0;
       SELECT i FROM t;
       BEGIN
         DECLARE i INT DEFAULT 1;
         SELECT i FROM t;
       END;
     END;

In such cases the identifier is ambiguous and the following precedence
rules apply:

   * A local variable takes precedence over a routine parameter or
     table column

   * A routine parameter takes precedence over a table column

   * A local variable in an inner block takes precedence over a local
     variable in an outer block

The behavior that variables take precedence over table columns is
non-standard.

Use of stored routines can cause replication problems. This issue is
discussed further in *Note stored-programs-logging::.

There are no stored routine debugging facilities.

`UNDO' handlers are not supported.

`FOR' loops are not supported.

To prevent problems of interaction between server threads, when a
client issues a statement, the server uses a snapshot of routines and
triggers available for execution of the statement. That is, the server
calculates a list of procedures, functions, and triggers that may be
used during execution of the statement, loads them, and then proceeds
to execute the statement. This means that while the statement executes,
it will not see changes to routines performed by other threads.

For triggers, the following additional statements or operations are
disallowed:

   * Triggers currently are not activated by foreign key actions.

   * When using row-based replication, triggers on the slave are not
     activated by statements originating on the master. This does not
     apply when using statement-based replication. For more
     information, see *Note replication-features-triggers::.

   * The *Note `RETURN': return. statement is disallowed in triggers,
     which cannot return a value. To exit a trigger immediately, use the
     *Note `LEAVE': leave-statement.  statement.

   * Triggers are not allowed on tables in the `mysql' database.

The following limitations are specific to the Event Scheduler:

   * Event names are handled in case-insensitive fashion. For example,
     this means that you cannot have two events in the same database
     with the names `anEvent' and `AnEvent'.

   * An event may not be created, altered, or dropped by a stored
     routine, trigger, or another event. An event also may not create,
     alter, or drop stored routines or triggers. (Bug#16409
     (http://bugs.mysql.com/16409), Bug#18896
     (http://bugs.mysql.com/18896))

   * Event timings using the intervals *Note `YEAR': year, `QUARTER',
     `MONTH', and `YEAR_MONTH' are resolved in months; those using any
     other interval are resolved in seconds. There is no way to cause
     events scheduled to occur at the same second to execute in a given
     order. In addition -- due to rounding, the nature of threaded
     applications, and the fact that a non-zero length of time is
     required to create events and to signal their execution -- events
     may be delayed by as much as 1 or 2 seconds. However, the time
     shown in the *Note `INFORMATION_SCHEMA.EVENTS': events-table.
     table's `LAST_EXECUTED' column or the `mysql.event' table's
     `last_executed' column is always accurate to within one second of
     the actual event execution time. (See also Bug#16522
     (http://bugs.mysql.com/16522).)

   * Each execution of the statements contained in the body of an event
     takes place in a new connection; thus, these statements has no
     effect in a given user session on the server's statement counts
     such as `Com_select' and `Com_insert' that are displayed by *Note
     `SHOW STATUS': show-status. However, such counts _are_ updated in
     the global scope.  (Bug#16422 (http://bugs.mysql.com/16422))

   * Events do not support times later than the end of the Unix Epoch;
     this is approximately the beginning of the year 2038.  Such dates
     are specifically disallowed by the Event Scheduler.  (Bug#16396
     (http://bugs.mysql.com/16396))

   * The `SQL_MODE' column in *Note `INFORMATION_SCHEMA.EVENTS':
     events-table. shows the server SQL mode that was in effect when
     the event was created.

   * *Note `DROP USER': drop-user. drops all events for which that user
     was the definer; *Note `DROP SCHEMA': drop-database. drops all
     events associated with the dropped schema.

   * References to stored functions, user-defined functions, and tables
     in the `ON SCHEDULE' clauses of *Note `CREATE EVENT':
     create-event. and *Note `ALTER EVENT': alter-event. statements are
     not supported. These sorts of references are disallowed. (See
     Bug#22830 (http://bugs.mysql.com/22830) for more information.)

   * Generally speaking, statements which are not permitted in stored
     routines or in SQL prepared statements are also not allowed in the
     body of an event. For more information, see *Note
     sql-syntax-prepared-statements::.


File: manual.info,  Node: signal-restrictions,  Next: cursor-restrictions,  Prev: stored-program-restrictions,  Up: restrictions

D.2 Restrictions on Signals
===========================

*Note `SIGNAL': signal. and *Note `RESIGNAL': resignal. are not
allowable as prepared statements. For example, this statement is
invalid:

     PREPARE stmt1 FROM 'SIGNAL SQLSTATE "02000"';

`SQLSTATE' values in class `'04'' are not treated specially. They are
handled the same as other exceptions.


File: manual.info,  Node: cursor-restrictions,  Next: subquery-restrictions,  Prev: signal-restrictions,  Up: restrictions

D.3 Restrictions on Server-Side Cursors
=======================================

Server-side cursors are implemented in the C API via the *Note
`mysql_stmt_attr_set()': mysql-stmt-attr-set. function.  The same
implementation is used for cursors in stored routines. A server-side
cursor allows a result set to be generated on the server side, but not
transferred to the client except for those rows that the client
requests. For example, if a client executes a query but is only
interested in the first row, the remaining rows are not transferred.

In MySQL, a server-side cursor is materialized into a temporary table.
Initially, this is a `MEMORY' table, but is converted to a `MyISAM'
table if its size reaches the value of the `max_heap_table_size' system
variable. One limitation of the implementation is that for a large
result set, retrieving its rows through a cursor might be slow.

Cursors are read only; you cannot use a cursor to update rows.

`UPDATE WHERE CURRENT OF' and `DELETE WHERE CURRENT OF' are not
implemented, because updatable cursors are not supported.

Cursors are non-holdable (not held open after a commit).

Cursors are asensitive.

Cursors are non-scrollable.

Cursors are not named. The statement handler acts as the cursor ID.

You can have open only a single cursor per prepared statement. If you
need several cursors, you must prepare several statements.

You cannot use a cursor for a statement that generates a result set if
the statement is not supported in prepared mode. This includes
statements such as *Note `CHECK TABLE': check-table, `HANDLER READ', and
*Note `SHOW BINLOG EVENTS': show-binlog-events.


File: manual.info,  Node: subquery-restrictions,  Next: view-restrictions,  Prev: cursor-restrictions,  Up: restrictions

D.4 Restrictions on Subqueries
==============================

   * In MySQL 6.0 before 6.0.10, if you compare a `NULL' value to a
     subquery using `ALL', `ANY', or `SOME', and the subquery returns
     an empty result, the comparison might evaluate to the non-standard
     result of `NULL' rather than to `TRUE' or `FALSE' for subqueries
     inside `IS NULL', such as this:

          SELECT ... WHERE NULL IN (SELECT ...) IS NULL

     As of 6.0.10, the `IS NULL' limitation is removed and the
     comparison evaluates to `TRUE' or `FALSE'.

   * A subquery's outer statement can be any one of: *Note `SELECT':
     select, *Note `INSERT': insert, *Note `UPDATE': update, *Note
     `DELETE': delete, *Note `SET': set-option, or *Note `DO': do.

   * Subquery optimization for `IN' is not as effective as for the `='
     operator or for the `IN(VALUE_LIST)' operator.

     A typical case for poor `IN' subquery performance is when the
     subquery returns a small number of rows but the outer query
     returns a large number of rows to be compared to the subquery
     result.

     The problem is that, for a statement that uses an `IN' subquery,
     the optimizer rewrites it as a correlated subquery. Consider the
     following statement that uses an uncorrelated subquery:

          SELECT ... FROM t1 WHERE t1.a IN (SELECT b FROM t2);

     The optimizer rewrites the statement to a correlated subquery:

          SELECT ... FROM t1 WHERE EXISTS (SELECT 1 FROM t2 WHERE t2.b = t1.a);

     If the inner and outer queries return M and N rows, respectively,
     the execution time becomes on the order of `O(MxN)', rather than
     `O(M+N)' as it would be for an uncorrelated subquery.

     An implication is that an `IN' subquery can be much slower than a
     query written using an `IN(VALUE_LIST)' operator that lists the
     same values that the subquery would return.

   * In general, you cannot modify a table and select from the same
     table in a subquery. For example, this limitation applies to
     statements of the following forms:

          DELETE FROM t WHERE ... (SELECT ... FROM t ...);
          UPDATE t ... WHERE col = (SELECT ... FROM t ...);
          {INSERT|REPLACE} INTO t (SELECT ... FROM t ...);

     Exception: The preceding prohibition does not apply if you are
     using a subquery for the modified table in the `FROM' clause.
     Example:

          UPDATE t ... WHERE col = (SELECT * FROM (SELECT ... FROM t...) AS _t ...);

     Here the prohibition does not apply because the result from a
     subquery in the `FROM' clause is stored as a temporary table, so
     the relevant rows in `t' have already been selected by the time
     the update to `t' takes place.

   * Row comparison operations are only partially supported:

        * For `EXPR IN (SUBQUERY)', EXPR can be an N-tuple (specified
          via row constructor syntax) and the subquery can return rows
          of N-tuples.

        * For `EXPR OP {ALL|ANY|SOME} (SUBQUERY)', EXPR must be a
          scalar value and the subquery must be a column subquery; it
          cannot return multiple-column rows.

     In other words, for a subquery that returns rows of N-tuples, this
     is supported:

          (VAL_1, ..., VAL_N) IN (SUBQUERY)

     But this is not supported:

          (VAL_1, ..., VAL_N) OP {ALL|ANY|SOME} (SUBQUERY)

     The reason for supporting row comparisons for `IN' but not for the
     others is that `IN' is implemented by rewriting it as a sequence
     of `=' comparisons and `AND' operations.  This approach cannot be
     used for `ALL', `ANY', or `SOME'.

   * Row constructors are not well optimized. The following two
     expressions are equivalent, but only the second can be optimized:

          (col1, col2, ...) = (val1, val2, ...)
          col1 = val1 AND col2 = val2 AND ...

   * Subqueries in the `FROM' clause cannot be correlated subqueries.
     They are materialized (executed to produce a result set) before
     evaluating the outer query, so they cannot be evaluated per row of
     the outer query.

   * The optimizer is more mature for joins than for subqueries, so in
     many cases a statement that uses a subquery can be executed more
     efficiently if you rewrite it as a join.

     An exception occurs for the case where an `IN' subquery can be
     rewritten as a `SELECT DISTINCT' join. Example:

          SELECT col FROM t1 WHERE id_col IN (SELECT id_col2 FROM t2 WHERE CONDITION);

     That statement can be rewritten as follows:

          SELECT DISTINCT col FROM t1, t2 WHERE t1.id_col = t2.id_col AND CONDITION;

     But in this case, the join requires an extra `DISTINCT' operation
     and is not more efficient than the subquery.

   * Possible future optimization: MySQL does not rewrite the join
     order for subquery evaluation. In some cases, a subquery could be
     executed more efficiently if MySQL rewrote it as a join.  This
     would give the optimizer a chance to choose between more execution
     plans. For example, it could decide whether to read one table or
     the other first.

     Example:

          SELECT a FROM outer_table AS ot
          WHERE a IN (SELECT a FROM inner_table AS it WHERE ot.b = it.b);

     For that query, MySQL always scans `outer_table' first and then
     executes the subquery on `inner_table' for each row. If
     `outer_table' has a lot of rows and `inner_table' has few rows,
     the query probably will not be as fast as it could be.

     The preceding query could be rewritten like this:

          SELECT a FROM outer_table AS ot, inner_table AS it
          WHERE ot.a = it.a AND ot.b = it.b;

     In this case, we can scan the small table (`inner_table') and look
     up rows in `outer_table', which will be fast if there is an index
     on `(ot.a,ot.b)'.

   * Possible future optimization: A correlated subquery is evaluated
     for each row of the outer query. A better approach is that if the
     outer row values do not change from the previous row, do not
     evaluate the subquery again. Instead, use its previous result.

   * Possible future optimization: A subquery in the `FROM' clause is
     evaluated by materializing the result into a temporary table, and
     this table does not use indexes. This does not allow the use of
     indexes in comparison with other tables in the query, although
     that might be useful.

   * Possible future optimization: If a subquery in the `FROM' clause
     resembles a view to which the merge algorithm can be applied,
     rewrite the query and apply the merge algorithm so that indexes
     can be used. The following statement contains such a subquery:

          SELECT * FROM (SELECT * FROM t1 WHERE t1.t1_col)
                   AS _t1, t2 WHERE t2.t2_col;

     The statement can be rewritten as a join like this:

          SELECT * FROM t1, t2 WHERE t1.t1_col AND t2.t2_col;

     This type of rewriting would provide two benefits:

        * It avoids the use of a temporary table for which no indexes
          can be used. In the rewritten query, the optimizer can use
          indexes on `t1'.

        * It gives the optimizer more freedom to choose between
          different execution plans. For example, rewriting the query
          as a join allows the optimizer to use `t1' or `t2' first.

   * Possible future optimization: For `IN', `= ANY', `<> ANY', `=
     ALL', and `<> ALL' with uncorrelated subqueries, use an in-memory
     hash for a result or a temporary table with an index for larger
     results.  Example:

          SELECT a FROM big_table AS bt
          WHERE non_key_field IN (SELECT non_key_field FROM TABLE WHERE CONDITION)

     In this case, we could create a temporary table:

          CREATE TABLE t (key (non_key_field))
          (SELECT non_key_field FROM TABLE WHERE CONDITION)

     Then, for each row in `big_table', do a key lookup in `t' based on
     `bt.non_key_field'.


File: manual.info,  Node: view-restrictions,  Next: xa-restrictions,  Prev: subquery-restrictions,  Up: restrictions

D.5 Restrictions on Views
=========================

View processing is not optimized:

   * It is not possible to create an index on a view.

   * Indexes can be used for views processed using the merge algorithm.
     However, a view that is processed with the temptable algorithm is
     unable to take advantage of indexes on its underlying tables
     (although indexes can be used during generation of the temporary
     tables).

Subqueries cannot be used in the `FROM' clause of a view.

There is a general principle that you cannot modify a table and select
from the same table in a subquery. See *Note subquery-restrictions::.

The same principle also applies if you select from a view that selects
from the table, if the view selects from the table in a subquery and
the view is evaluated using the merge algorithm.  Example:

     CREATE VIEW v1 AS
     SELECT * FROM t2 WHERE EXISTS (SELECT 1 FROM t1 WHERE t1.a = t2.a);

     UPDATE t1, v2 SET t1.a = 1 WHERE t1.b = v2.b;

If the view is evaluated using a temporary table, you _can_ select from
the table in the view subquery and still modify that table in the outer
query. In this case the view will be stored in a temporary table and
thus you are not really selecting from the table in a subquery and
modifying it `at the same time.' (This is another reason you might wish
to force MySQL to use the temptable algorithm by specifying `ALGORITHM
= TEMPTABLE' in the view definition.)

You can use *Note `DROP TABLE': drop-table. or *Note `ALTER TABLE':
alter-table. to drop or alter a table that is used in a view
definition. No warning results from the `DROP' or `ALTER' operation,
even though this invalidates the view. Instead, an error occurs later,
when the view is used. *Note `CHECK TABLE': check-table. can be used to
check for views that have been invalidated by `DROP' or `ALTER'
operations.

A view definition is `frozen' by certain statements:

   * If a statement prepared by *Note `PREPARE': prepare. refers to a
     view, the view definition seen each time the statement is executed
     later will be the definition of the view at the time it was
     prepared. This is true even if the view definition is changed
     after the statement is prepared and before it is executed.
     Example:

          CREATE VIEW v AS SELECT RAND();
          PREPARE s FROM 'SELECT * FROM v';
          ALTER VIEW v AS SELECT NOW();
          EXECUTE s;

     The result returned by the *Note `EXECUTE': execute. statement is
     a random number, not the current date and time.

With regard to view updatability, the overall goal for views is that if
any view is theoretically updatable, it should be updatable in
practice. This includes views that have *Note `UNION': union. in their
definition.  Currently, not all views that are theoretically updatable
can be updated. The initial view implementation was deliberately written
this way to get usable, updatable views into MySQL as quickly as
possible. Many theoretically updatable views can be updated now, but
limitations still exist:

   * Updatable views with subqueries anywhere other than in the `WHERE'
     clause. Some views that have subqueries in the *Note `SELECT':
     select. list may be updatable.

   * You cannot use *Note `UPDATE': update. to update more than one
     underlying table of a view that is defined as a join.

   * You cannot use *Note `DELETE': delete. to update a view that is
     defined as a join.

There exists a shortcoming with the current implementation of views. If
a user is granted the basic privileges necessary to create a view (the
`CREATE VIEW' and `SELECT' privileges), that user will be unable to
call *Note `SHOW CREATE VIEW': show-create-view.  on that object unless
the user is also granted the `SHOW VIEW' privilege.

That shortcoming can lead to problems backing up a database with *Note
`mysqldump': mysqldump, which may fail due to insufficient privileges.
This problem is described in Bug#22062 (http://bugs.mysql.com/22062).

The workaround to the problem is for the administrator to manually
grant the `SHOW VIEW' privilege to users who are granted `CREATE VIEW',
since MySQL doesn't grant it implicitly when views are created.

Views do not have indexes, so index hints do not apply. Use of index
hints when selecting from a view is disallowed.

*Note `SHOW CREATE VIEW': show-create-view. displays view definitions
using an `AS ALIAS_NAME' clause for each column. If a column is created
from an expression, the default alias is the expression text, which can
be quite long. As of MySQL 6.0.4, aliases for column names in *Note
`CREATE VIEW': create-view. statements are checked against the maximum
column length of 64 characters (not the maximum alias length of 256
characters). As a result, views created from the output of *Note `SHOW
CREATE VIEW': show-create-view. fail if any column alias exceeds 64
characters. This can cause problems in the following circumstances for
views with too-long aliases:

   * View definitions fail to replicate to newer slaves that enforce
     the column-length restriction.

   * Dump files created with *Note `mysqldump': mysqldump. cannot be
     loaded into servers that enforce the column-length restriction.

A workaround for either problem is the modify each problematic view
definition to use aliases that provide shorter column names.  Then the
view will replicate properly, and can be dumped and reloaded without
causing an error. To modify the definition, drop and create the view
again with *Note `DROP VIEW': drop-view. and *Note `CREATE VIEW':
create-view, or replace the definition with *Note `CREATE OR REPLACE
VIEW': create-view.

For problems that occur when reloading view definitions in dump files,
another workaround is to edit the dump file to modify its *Note `CREATE
VIEW': create-view. statements. However, this does not change the
original view definitions, which may cause problems for subsequent dump
operations.


File: manual.info,  Node: xa-restrictions,  Next: charset-restrictions,  Prev: view-restrictions,  Up: restrictions

D.6 Restrictions on XA Transactions
===================================

XA transaction support is limited to the `InnoDB' storage engine.

For `external XA,' a MySQL server acts as a Resource Manager and client
programs act as Transaction Managers. For `Internal XA', storage
engines within a MySQL server act as RMs, and the server itself acts as
a TM. Internal XA support is limited by the capabilities of individual
storage engines. Internal XA is required for handling XA transactions
that involve more than one storage engine. The implementation of
internal XA requires that a storage engine support two-phase commit at
the table handler level, and currently this is true only for `InnoDB'.

For *Note `XA START': xa-statements, the `JOIN' and `RESUME' clauses
are not supported.

For *Note `XA END': xa-statements, the `SUSPEND [FOR MIGRATE]' clause
is not supported.

The requirement that the BQUAL part of the XID value be different for
each XA transaction within a global transaction is a limitation of the
current MySQL XA implementation. It is not part of the XA specification.

If an XA transaction has reached the `PREPARED' state and the MySQL
server is killed (for example, with *Note `kill -9': kill. on Unix) or
shuts down abnormally, the transaction can be continued after the
server restarts. However, if the client reconnects and commits the
transaction, the transaction will be absent from the binary log even
though it has been committed. This means the data and the binary log
have gone out of synchrony. An implication is that XA cannot be used
safely together with replication.

It is possible that the server will roll back a pending XA transaction,
even one that has reached the `PREPARED' state. This happens if a client
connection terminates and the server continues to run, or if clients
are connected and the server shuts down gracefully. (In the latter
case, the server marks each connection to be terminated, and then rolls
back the `PREPARED' XA transaction associated with it.) It should be
possible to commit or roll back a `PREPARED' XA transaction, but this
cannot be done without changes to the binary logging mechanism.


File: manual.info,  Node: charset-restrictions,  Next: backup-database-restore-restrictions,  Prev: xa-restrictions,  Up: restrictions

D.7 Restrictions on Character Sets
==================================

   * Identifiers are stored in `mysql' database tables (`user', `db',
     and so forth) using `utf8', but identifiers can contain only
     characters in the Basic Multilingual Plane (BMP).  Supplementary
     characters are not allowed in identifiers.

   * The `ucs2', `utf16', and `utf32' character sets have the following
     restrictions:

        * They cannot be used as a client character set, which means
          that they do not work for `SET NAMES' or `SET CHARACTER SET'.
          (See *Note charset-connection::.)

        * It is currently not possible to use *Note `LOAD DATA INFILE':
          load-data. to load data files that use these character sets.

        * `FULLTEXT' indexes cannot be created on a column that uses
          any of these character sets. However, you can perform `IN
          BOOLEAN MODE' searches on the column without an index.

   * The `REGEXP' and `RLIKE' operators work in byte-wise fashion, so
     they are not multi-byte safe and may produce unexpected results
     with multi-byte character sets. In addition, these operators
     compare characters by their byte values and accented characters
     may not compare as equal even if a given collation treats them as
     equal.


File: manual.info,  Node: backup-database-restore-restrictions,  Next: limits,  Prev: charset-restrictions,  Up: restrictions

D.8 Restrictions on `BACKUP DATABASE' and `RESTORE'
===================================================

Currently, the *Note `BACKUP DATABASE': backup-database. and *Note
`RESTORE': restore. statements have these limitations:

   * *Note `BACKUP DATABASE': backup-database. backs up database and
     table definitions, table data, stored routines, triggers, events,
     and views. `TEMPORARY' tables are not included. Tablespace backup
     support is limited to the `Falcon' storage engine. Privileges are
     not saved before MySQL 6.0.7. As of 6.0.7, privileges for
     backed-up databases are saved. This includes privileges at the
     database level and below (table, column, routine). Global
     privileges are not saved.

     For anything else not explicitly listed, assume that it is not
     backed up. This includes but is not limited to items such as UDF
     definitions and files, logs, and option files.

   * The *Note `BACKUP DATABASE': backup-database. statement does not
     back up the `mysql' or `INFORMATION_SCHEMA' databases.

   * There is no way to determine the contents of a backup image
     produced with *Note `BACKUP DATABASE': backup-database.  That is,
     you cannot determine which databases are in a given backup image
     and will be restored by using it with *Note `RESTORE': restore.

   * Before MySQL 6.0.9, *Note `RESTORE': restore. is a destructive
     operation. Each restored database is first dropped and then
     created and populated with the tables contained in the backup
     image. There is no warning about existing data being overwritten.
     As of MySQL 6.0.9, *Note `RESTORE': restore. aborts with an error
     if the backup image contains any databases that currently exist on
     the server, unless the optional keyword `OVERWRITE' is given
     following the image file name.

   * *Note `BACKUP DATABASE': backup-database. and *Note `RESTORE':
     restore. cannot be used in stored routines, triggers, or events.

   * *Note `BACKUP DATABASE': backup-database. and *Note `RESTORE':
     restore. cannot be used as prepared statements.

   * `Falcon' tablespaces must not change characteristics between *Note
     `BACKUP DATABASE': backup-database. and *Note `RESTORE': restore.
     A restore of databases containing tables in a modified tablespace
     will fail. Suppose that you back up a database containing a
     `Falcon' table. If you modify the tablespace characteristics, or
     drop or lose and then re-create it with characteristics not the
     same as originally, restoration of the database will fail.

   * The backup image is consistent and has a well-defined validity
     point regardless of the storage engines used. However,
     non-transactional tables are locked for the duration of the *Note
     `BACKUP DATABASE': backup-database. operation if they use a
     storage engine other than `MyISAM' (such as `ARCHIVE' or `MEMORY').


File: manual.info,  Node: limits,  Prev: backup-database-restore-restrictions,  Up: restrictions

D.9 Limits in MySQL
===================

* Menu:

* joins-limits::                 Limits of Joins
* column-count-limit::           The Maximum Number of Columns Per Table
* limits-windows::               Windows Platform Limitations

This section lists current limits in MySQL 6.0.


File: manual.info,  Node: joins-limits,  Next: column-count-limit,  Prev: limits,  Up: limits

D.9.1 Limits of Joins
---------------------

The maximum number of tables that can be referenced in a single join is
61. This also applies to the number of tables that can be referenced in
the definition of a view.


File: manual.info,  Node: column-count-limit,  Next: limits-windows,  Prev: joins-limits,  Up: limits

D.9.2 The Maximum Number of Columns Per Table
---------------------------------------------

There is a hard limit of 4096 columns per table, but the effective
maximum may be less for a given table. The exact limit depends on
several interacting factors, listed in the following discussion.

   * Every table has a maximum row size of 65,535 bytes. This maximum
     applies to all storage engines, but a given engine might have
     additional constraints that result in a lower effective maximum
     row size.

     The maximum row size constrains the number of columns because the
     total width of all columns cannot exceed this size. For example,
     `utf8' characters require up to four bytes per character, so for a
     `CHAR(255) CHARACTER SET utf8' column, the server must allocate
     255 x 4 = 1020 bytes per value.  Consequently, a table cannot
     contain more than 65,535 / 1020 = 64 such columns.

     Storage for variable-length columns includes length bytes, which
     are assessed against the row size. For example, a `VARCHAR(255)
     CHARACTER SET utf8' column takes two bytes to store the length of
     the value, so each value can take up to 1022 bytes.

     *Note `BLOB': blob. and *Note `TEXT': blob. columns count from one
     to four plus eight bytes each toward the row-size limit because
     their contents are stored separately.

     Declaring columns `NULL' can reduce the maximum number of columns
     allowed. `NULL' columns require additional space in the row to
     record whether or not their values are `NULL'.

     For `MyISAM' tables, each `NULL' column takes one bit extra,
     rounded up to the nearest byte. The maximum row length in bytes can
     be calculated as follows:

          row length = 1
                       + (SUM OF COLUMN LENGTHS)
                       + (NUMBER OF NULL COLUMNS + DELETE_FLAG + 7)/8
                       + (NUMBER OF VARIABLE-LENGTH COLUMNS)

     DELETE_FLAG is 1 for tables with static row format. Static tables
     use a bit in the row record for a flag that indicates whether the
     row has been deleted.  DELETE_FLAG is 0 for dynamic tables because
     the flag is stored in the dynamic row header.

     These calculations do not apply for `InnoDB' tables, for which
     storage size is no different for `NULL' columns than for `NOT
     NULL' columns.

     The following statement to create table `t1' succeeds because the
     columns require 32,765 + 2 bytes and 32,766 + 2 bytes, which falls
     within the maximum row size of 65,535 bytes:

          mysql> CREATE TABLE t1
              -> (c1 VARCHAR(32765) NOT NULL, c2 VARCHAR(32766) NOT NULL);
          Query OK, 0 rows affected (0.01 sec)

     The following statement to create table `t2' fails because the
     columns are `NULL' and require additional space that causes the
     row size to exceed 65,535 bytes:

          mysql> CREATE TABLE t2
              -> (c1 VARCHAR(32765) NULL, c2 VARCHAR(32766) NULL);
          ERROR 1118 (42000): Row size too large. The maximum row size for the
          used table type, not counting BLOBs, is 65535. You have to change some
          columns to TEXT or BLOBs

   * Each table has an `.frm' file that contains the table definition.
     The `.frm' file size limit is fixed at 64KB. If a table definition
     reaches this size, no more columns can be added. The expression
     that checks information to be stored in the `.frm' file against
     the limit looks like this:

          if (info_length+(ulong) create_fields.elements*FCOMP+288+
              n_length+int_length+com_length > 65535L || int_count > 255)

     The relevant factors in this expression are:

        * `info_length' is space needed for `screens.' This is related
          to MySQL's Unireg heritage.

        * `create_fields.elements' is the number of columns.

        * `FCOMP' is 17.

        * `n_length' is the total length of all column names, including
          one byte per name as a separator.

        * `int_length' is related to the list of values for SET and
          ENUM columns.

        * `com_length' is the total length of column and table comments.

     Thus, using long column names can reduce the maximum number of
     columns, as can the inclusion of *Note `ENUM': enum. or *Note
     `SET': set. columns, or use of column or table comments.

   * Individual storage engines might impose additional restrictions
     that limit table column count. Examples:

        * `InnoDB' allows no more than 1000 columns.

        * `InnoDB' restricts row size to something less than half a
          database page (approximately 8000 bytes), not including *Note
          `VARBINARY': binary-varbinary, *Note `VARCHAR': char, *Note
          `BLOB': blob, or *Note `TEXT': blob. columns.

        * Different `InnoDB' storage formats (`COMPRESSED',
          `REDUNDANT') use different amounts of page header and trailer
          data, which affects the amount of storage available for rows.


File: manual.info,  Node: limits-windows,  Prev: column-count-limit,  Up: limits

D.9.3 Windows Platform Limitations
----------------------------------

The following limitations apply only to the Windows platform:

   * The number of open file descriptors on Windows is limited to a
     maximum of 2048, which may limit the ability to open a large
     number of tables simultaneously. This limit is due to the
     compatibility functions used to open files on Windows that use the
     POSIX compatibility layer.

     This limitation will also cause problems if you try to set
     `open_files_limit' to a value greater than the 2048 file limit.

   * On Windows 32-bit platforms it is not possible to use more than
     2GB of RAM within a single process, including MySQL.  This is
     because the physical address limit on Windows 32-bit is 4GB and
     the default setting within Windows is to split the virtual address
     space between kernel (2GB) and user/applications (2GB).

     To use more memory than this you will need to use a 64-bit version
     of Windows.

   * When using `MyISAM' tables, you cannot use aliases within Windows
     link to the data files on another volume and then link back to the
     main MySQL `datadir' location.

     This facility is often used to move the data and index files to a
     RAID or other fast solution, while retaining the main `.FRM' files
     in the default data directory configured with the `datadir' option.

   * The timers within MySQL used on Windows are of a lower precision
     than the timers used on Linux. For most situations you may not
     notice a difference, but the delay implied by a call to `SLEEP()'
     on Windows and Linux may differ slightly due to the differences in
     precision.

   * There is no 64-bit OLEDB Provider for ODBC (MSDASQL) in any 64-bit
     Windows operating system up to and including Windows Vista. In
     practical terms this means that you can't use the MySQL ODBC
     driver from ADO and other users of OLEDB.

[index]
* Menu:

* ! (logical NOT):                       logical-operators.  (line   27)
* != (not equal):                        comparison-operators.
                                                             (line   89)
* ":                                     identifiers.        (line   20)
* #mysql50 identifier prefix <1>:        identifier-mapping. (line   76)
* #mysql50 identifier prefix:            identifiers.        (line   89)
* %:                                     arithmetic-functions.
                                                             (line  120)
* % (modulo):                            mathematical-functions.
                                                             (line  301)
* % (wildcard character):                string-syntax.      (line   64)
* & (bitwise AND):                       bit-functions.      (line   27)
* && (logical AND):                      logical-operators.  (line   46)
* () (parentheses):                      operator-precedence.
                                                             (line   37)
* (Control-Z) \Z <1>:                    load-data.          (line  429)
* (Control-Z) \Z:                        string-syntax.      (line   62)
* * (multiplication):                    arithmetic-functions.
                                                             (line   72)
* + (addition):                          arithmetic-functions.
                                                             (line   44)
* - (subtraction):                       arithmetic-functions.
                                                             (line   51)
* - (unary minus):                       arithmetic-functions.
                                                             (line   58)
* -p option:                             password-security-user.
                                                             (line   17)
* -password option:                      password-security-user.
                                                             (line   17)
* .my.cnf file <1>:                      multiple-server-clients.
                                                             (line   34)
* .my.cnf file <2>:                      password-security-user.
                                                             (line   56)
* .my.cnf file <3>:                      access-denied.      (line  108)
* .my.cnf file <4>:                      option-files.       (line   11)
* .my.cnf file:                          connecting.         (line  221)
* .mysql_history file <1>:               password-security-user.
                                                             (line   82)
* .mysql_history file:                   mysql-command-options.
                                                             (line  562)
* .pid (process ID) file:                maintenance-schedule.
                                                             (line   17)
* / (division):                          arithmetic-functions.
                                                             (line   88)
* /etc/passwd <1>:                       select.             (line  325)
* /etc/passwd:                           security-against-attack.
                                                             (line  112)
* := (assignment):                       user-variables.     (line    6)
* < (less than):                         comparison-operators.
                                                             (line  107)
* <<:                                    calculating-days.   (line    6)
* << (left shift):                       bit-functions.      (line   49)
* <= (less than or equal):               comparison-operators.
                                                             (line  100)
* <=> (equal to):                        comparison-operators.
                                                             (line   77)
* <> (not equal):                        comparison-operators.
                                                             (line   89)
* = (assignment):                        user-variables.     (line    6)
* = (equal):                             comparison-operators.
                                                             (line   62)
* > (greater than):                      comparison-operators.
                                                             (line  121)
* >= (greater than or equal):            comparison-operators.
                                                             (line  114)
* >> (right shift):                      bit-functions.      (line   61)
* \" (double quote):                     string-syntax.      (line   57)
* \' (single quote):                     string-syntax.      (line   56)
* \. (mysql client command) <1>:         batch-commands.     (line    6)
* \. (mysql client command):             batch-mode.         (line   90)
* \0 (ASCII NUL) <1>:                    load-data.          (line  424)
* \0 (ASCII NUL):                        string-syntax.      (line   55)
* \\ (escape):                           string-syntax.      (line   63)
* \b (backspace) <1>:                    load-data.          (line  425)
* \b (backspace):                        string-syntax.      (line   58)
* \n (linefeed) <1>:                     load-data.          (line  426)
* \n (linefeed):                         string-syntax.      (line   59)
* \n (newline) <1>:                      load-data.          (line  426)
* \n (newline):                          string-syntax.      (line   59)
* \N (NULL):                             load-data.          (line  430)
* \r (carriage return) <1>:              load-data.          (line  427)
* \r (carriage return):                  string-syntax.      (line   60)
* \t (tab) <1>:                          load-data.          (line  428)
* \t (tab):                              string-syntax.      (line   61)
* \Z (Control-Z) ASCII 26 <1>:           load-data.          (line  429)
* \Z (Control-Z) ASCII 26:               string-syntax.      (line   62)
* ^ (bitwise XOR):                       bit-functions.      (line   36)
* _ (wildcard character):                string-syntax.      (line   65)
* _rowid:                                create-table.       (line  355)
* `:                                     identifiers.        (line   20)
* abort-slave-event-count option, mysqld: replication-options-slave.
                                                             (line  668)
* aborted clients:                       communication-errors.
                                                             (line    6)
* aborted connection:                    communication-errors.
                                                             (line    6)
* ABS():                                 mathematical-functions.
                                                             (line   52)
* access control:                        connection-access.  (line    6)
* access denied errors:                  error-access-denied.
                                                             (line    6)
* access privileges:                     privilege-system.   (line   16)
* account names:                         account-names.      (line    6)
* account privileges, adding:            adding-users.       (line    6)
* accounts, anonymous user:              default-privileges. (line    6)
* accounts, root:                        default-privileges. (line    6)
* ACID <1>:                              innodb.             (line   23)
* ACID:                                  ansi-diff-transactions.
                                                             (line    6)
* ACLs:                                  privilege-system.   (line   16)
* ACOS():                                mathematical-functions.
                                                             (line   64)
* Active Server Pages (ASP):             connector-odbc-usagenotes-apptips-microsoft-asp.
                                                             (line    6)
* ActiveState Perl:                      activestate-perl.   (line    6)
* add-drop-database option, mysqldump:   mysqldump.          (line  262)
* add-drop-table option, mysqldump:      mysqldump.          (line  267)
* add-locks option, mysqldump:           mysqldump.          (line  272)
* ADDDATE():                             date-and-time-functions.
                                                             (line  130)
* adding, character sets:                adding-character-set.
                                                             (line   12)
* adding, native functions:              adding-native-function.
                                                             (line    6)
* adding, new account privileges:        adding-users.       (line    6)
* adding, new functions:                 adding-functions.   (line   12)
* adding, new user privileges:           adding-users.       (line    6)
* adding, new users <1>:                 quick-install.      (line  167)
* adding, new users:                     installing-binary.  (line  168)
* adding, procedures:                    adding-procedures.  (line   11)
* adding, user-defined functions:        adding-udf.         (line   15)
* addition (+):                          arithmetic-functions.
                                                             (line   44)
* ADDTIME():                             date-and-time-functions.
                                                             (line  148)
* addtodest option, mysqlhotcopy:        mysqlhotcopy.       (line   73)
* administration, server:                mysqladmin.         (line    6)
* administrative programs:               programs-overview.  (line  152)
* AES_DECRYPT():                         encryption-functions.
                                                             (line   42)
* AES_ENCRYPT():                         encryption-functions.
                                                             (line   48)
* After create, thread state:            general-thread-states.
                                                             (line   11)
* age, calculating:                      date-calculations.  (line    6)
* alias:                                 problems-with-alias.
                                                             (line    6)
* alias names, case sensitivity:         identifier-case-sensitivity.
                                                             (line    6)
* aliases, for expressions:              group-by-hidden-columns.
                                                             (line   52)
* aliases, for tables:                   select.             (line  157)
* aliases, in GROUP BY clauses:          group-by-hidden-columns.
                                                             (line   52)
* aliases, names:                        identifiers.        (line   13)
* aliases, on expressions:               select.             (line  104)
* ALL <1>:                               all-subqueries.     (line    6)
* ALL:                                   select.             (line  446)
* ALL join type, optimizer:              using-explain.      (line  271)
* all option, mysqlbackup:               mysqlbackup.        (line   77)
* all-databases option, mysqlcheck:      mysqlcheck.         (line  167)
* all-databases option, mysqldump:       mysqldump.          (line  279)
* all-in-1 option, mysqlcheck:           mysqlcheck.         (line  173)
* allocating local table, thread state:  delayed-insert-thread-states.
                                                             (line   17)
* allow-keywords option, mysqldump:      mysqldump.          (line  285)
* allow-suspicious-udfs option, mysqld <1>: privileges-options.
                                                             (line   37)
* allow-suspicious-udfs option, mysqld:  server-options.     (line   60)
* ALLOW_INVALID_DATES SQL mode:          server-sql-mode.    (line   87)
* allowold option, mysqlhotcopy:         mysqlhotcopy.       (line   78)
* ALTER COLUMN:                          alter-table.        (line  282)
* ALTER DATABASE:                        alter-database.     (line    6)
* ALTER EVENT:                           alter-event.        (line    6)
* ALTER FUNCTION:                        alter-function.     (line    6)
* ALTER PROCEDURE:                       alter-procedure.    (line    6)
* ALTER SCHEMA:                          alter-database.     (line    6)
* ALTER SERVER:                          alter-server.       (line    6)
* ALTER TABLE <1>:                       alter-table-problems.
                                                             (line    6)
* ALTER TABLE:                           alter-table.        (line    6)
* ALTER VIEW:                            alter-view.         (line    6)
* altering, database:                    alter-database.     (line    6)
* altering, schema:                      alter-database.     (line    6)
* analyze option, myisamchk:             myisamchk-other-options.
                                                             (line    9)
* analyze option, mysqlcheck:            mysqlcheck.         (line  179)
* ANALYZE TABLE:                         analyze-table.      (line    6)
* ANALYZE TABLE, and partitioning:       partitioning-maintenance.
                                                             (line    6)
* Analyzing, thread state:               general-thread-states.
                                                             (line   18)
* AND, bitwise:                          bit-functions.      (line   27)
* AND, logical:                          logical-operators.  (line   46)
* anonymous user <1>:                    request-access.     (line   27)
* anonymous user <2>:                    connection-access.  (line   25)
* anonymous user:                        default-privileges. (line    6)
* ANSI mode, running:                    ansi-mode.          (line    6)
* ansi option, mysqld:                   server-options.     (line   76)
* ANSI SQL mode:                         server-sql-mode.    (line   55)
* ANSI_QUOTES SQL mode:                  server-sql-mode.    (line  105)
* answering questions, etiquette:        mailing-list-use.   (line    6)
* ANY:                                   any-in-some-subqueries.
                                                             (line    6)
* Apache:                                apache.             (line    6)
* API's, list of:                        packages.           (line    6)
* APIs:                                  connectors-apis.    (line   26)
* APIs, Perl:                            apis-perl.          (line    6)
* apply-slave-statements option, mysqldump: mysqldump.       (line  290)
* approximate-value literals:            precision-math.     (line   14)
* ARCHIVE storage engine <1>:            archive-storage-engine.
                                                             (line    6)
* ARCHIVE storage engine:                storage-engines.    (line   24)
* Area() <1>:                            multipolygon-property-functions.
                                                             (line    8)
* Area():                                polygon-property-functions.
                                                             (line    8)
* argument processing:                   udf-arguments.      (line    6)
* arithmetic expressions:                arithmetic-functions.
                                                             (line   44)
* arithmetic functions:                  bit-functions.      (line    6)
* AS <1>:                                join.               (line    6)
* AS:                                    select.             (line  131)
* AsBinary():                            functions-to-convert-geometries-between-formats.
                                                             (line    9)
* ASCII():                               string-functions.   (line  102)
* ASIN():                                mathematical-functions.
                                                             (line   76)
* AsText():                              functions-to-convert-geometries-between-formats.
                                                             (line   16)
* ATAN():                                mathematical-functions.
                                                             (line   99)
* ATAN2():                               mathematical-functions.
                                                             (line  109)
* attackers, security against:           security-against-attack.
                                                             (line    6)
* attribute promotion, replication:      replication-features-different-data-types.
                                                             (line   14)
* auto-generate-sql option, mysqlslap:   mysqlslap.          (line  196)
* auto-generate-sql-add-autoincrement option, mysqlslap: mysqlslap.
                                                             (line  201)
* auto-generate-sql-execute-number option, mysqlslap: mysqlslap.
                                                             (line  205)
* auto-generate-sql-guid-primary option, mysqlslap: mysqlslap.
                                                             (line  209)
* auto-generate-sql-load-type option, mysqlslap: mysqlslap.  (line  213)
* auto-generate-sql-secondary-indexes option, mysqlslap: mysqlslap.
                                                             (line  220)
* auto-generate-sql-select-columns option, mysqlslap: mysqlslap.
                                                             (line  225)
* auto-generate-sql-unique-query-number option, mysqlslap: mysqlslap.
                                                             (line  232)
* auto-generate-sql-unique-write-number option, mysqlslap: mysqlslap.
                                                             (line  240)
* auto-generate-sql-write-number option, mysqlslap: mysqlslap.
                                                             (line  245)
* AUTO-INCREMENT, ODBC:                  connector-odbc-usagenotes-functionality-last-insert-id.
                                                             (line    6)
* auto-rehash option, mysql:             mysql-command-options.
                                                             (line  134)
* auto-repair option, mysqlcheck:        mysqlcheck.         (line  189)
* auto-vertical-output option, mysql:    mysql-command-options.
                                                             (line  148)
* AUTO_INCREMENT <1>:                    numeric-types.      (line    6)
* AUTO_INCREMENT:                        example-auto-increment.
                                                             (line    6)
* AUTO_INCREMENT, and NULL values:       problems-with-null. (line   71)
* AUTO_INCREMENT, and replication:       replication-features-auto-increment.
                                                             (line    6)
* auto_increment_increment system variable: replication-options-master.
                                                             (line   21)
* auto_increment_offset system variable: replication-options-master.
                                                             (line  215)
* autoclose option, mysqld_safe:         mysqld-safe.        (line  103)
* autocommit session variable:           server-session-variables.
                                                             (line   58)
* automatic_sp_privileges system variable: server-system-variables.
                                                             (line  525)
* AVG():                                 group-by-functions. (line   55)
* AVG(DISTINCT):                         group-by-functions. (line   55)
* back_log system variable:              server-system-variables.
                                                             (line  623)
* backslash, escape character:           literals.           (line   15)
* backspace (\b) <1>:                    load-data.          (line  425)
* backspace (\b):                        string-syntax.      (line   58)
* BACKUP DATABASE:                       backup-database.    (line    6)
* BACKUP DATABASE restrictions:          backup-database-restore-restrictions.
                                                             (line    6)
* backup option, myisamchk:              myisamchk-repair-options.
                                                             (line    9)
* backup option, myisampack:             myisampack.         (line   53)
* backup_history_log system variable:    server-system-variables.
                                                             (line  543)
* backup_history_log_file system variable: server-system-variables.
                                                             (line  565)
* backup_progress_log system variable:   server-system-variables.
                                                             (line  583)
* backup_progress_log_file system variable: server-system-variables.
                                                             (line  605)
* backup_wait_timeout session variable:  server-session-variables.
                                                             (line   70)
* backupdir system variable:             server-system-variables.
                                                             (line  655)
* backups:                               backup-and-recovery.
                                                             (line   14)
* backups, databases and tables <1>:     mysqlhotcopy.       (line    6)
* backups, databases and tables:         mysqldump.          (line    6)
* base64-output option, mysqlbinlog:     mysqlbinlog.        (line  128)
* basedir option, mysql.server:          mysql-server.       (line   36)
* basedir option, mysql_install_db:      mysql-install-db.   (line   42)
* basedir option, mysql_upgrade:         mysql-upgrade.      (line   90)
* basedir option, mysqld:                server-options.     (line   86)
* basedir option, mysqld_safe:           mysqld-safe.        (line  115)
* basedir system variable:               server-system-variables.
                                                             (line  693)
* batch mode:                            batch-mode.         (line    6)
* batch option, mysql:                   mysql-command-options.
                                                             (line  155)
* batch SQL files:                       mysql.              (line   14)
* Batched Key Access, optimization <1>:  bka-optimization.   (line    6)
* Batched Key Access, optimization:      bnl-bka-optimization.
                                                             (line   12)
* Bazaar tree:                           installing-source-tree.
                                                             (line    6)
* BdMPolyFromText():                     gis-wkt-functions.  (line   59)
* BdMPolyFromWKB():                      gis-wkb-functions.  (line   59)
* BdPolyFromText():                      gis-wkt-functions.  (line   65)
* BdPolyFromWKB():                       gis-wkb-functions.  (line   65)
* BEGIN <1>:                             begin-end.          (line    6)
* BEGIN:                                 commit.             (line    6)
* BEGIN, XA transactions:                xa-statements.      (line    6)
* benchmark suite:                       mysql-benchmarks.   (line    6)
* BENCHMARK():                           information-functions.
                                                             (line   30)
* benchmarks:                            custom-benchmarks.  (line    6)
* BETWEEN ... AND:                       comparison-operators.
                                                             (line  179)
* big-tables option, mysqld:             server-options.     (line  102)
* big5:                                  faqs-cjk.           (line   20)
* big_tables session variable:           server-session-variables.
                                                             (line   78)
* BIGINT data type:                      numeric-type-overview.
                                                             (line  127)
* BIN():                                 string-functions.   (line  117)
* BINARY:                                cast-functions.     (line   11)
* BINARY data type <1>:                  binary-varbinary.   (line    6)
* BINARY data type:                      string-type-overview.
                                                             (line  151)
* binary distributions:                  mysql-binaries.     (line    6)
* binary distributions, installing:      installing-binary.  (line    6)
* binary distributions, on Linux:        binary-notes-linux. (line    6)
* binary log:                            binary-log.         (line   13)
* binary log, event groups:              set-global-sql-slave-skip-counter.
                                                             (line    6)
* bind-address option, mysqld:           server-options.     (line  122)
* BINLOG:                                binlog.             (line    6)
* Binlog Dump, thread command:           thread-commands.    (line    8)
* binlog-do-db option, mysqld:           replication-options-binary-log.
                                                             (line   87)
* binlog-format option, mysqld:          server-options.     (line  139)
* binlog-ignore-db option, mysqld:       replication-options-binary-log.
                                                             (line  186)
* binlog-row-event-max-size option, mysqld: replication-options-binary-log.
                                                             (line   23)
* binlog_cache_size system variable:     replication-options-binary-log.
                                                             (line  302)
* binlog_format system variable:         replication-options-binary-log.
                                                             (line  339)
* BIT data type:                         numeric-type-overview.
                                                             (line   35)
* BIT_AND():                             group-by-functions. (line   66)
* BIT_COUNT:                             calculating-days.   (line    6)
* BIT_COUNT():                           bit-functions.      (line   82)
* bit_functions, example:                calculating-days.   (line    6)
* BIT_LENGTH():                          string-functions.   (line  126)
* BIT_OR:                                calculating-days.   (line    6)
* BIT_OR():                              group-by-functions. (line   75)
* BIT_XOR():                             group-by-functions. (line   82)
* BitKeeper tree:                        installing-source-tree.
                                                             (line    6)
* BLACKHOLE storage engine <1>:          blackhole-storage-engine.
                                                             (line    6)
* BLACKHOLE storage engine:              storage-engines.    (line   24)
* BLOB columns, default values:          blob.               (line   55)
* BLOB columns, indexing <1>:            create-table.       (line  404)
* BLOB columns, indexing:                indexes.            (line   15)
* BLOB data type <1>:                    blob.               (line    6)
* BLOB data type:                        string-type-overview.
                                                             (line  180)
* BLOB, inserting binary data:           string-syntax.      (line  140)
* BLOB, size:                            storage-requirements.
                                                             (line  131)
* Block Nested-Loop join algorithm:      nested-loop-joins.  (line    6)
* Block Nested-Loop, optimization <1>:   bnl-optimization.   (line    6)
* Block Nested-Loop, optimization:       bnl-bka-optimization.
                                                             (line   12)
* block-search option, myisamchk:        myisamchk-other-options.
                                                             (line   24)
* BOOL data type:                        numeric-type-overview.
                                                             (line   45)
* BOOLEAN data type:                     numeric-type-overview.
                                                             (line   45)
* bootstrap option, mysqld:              server-options.     (line  159)
* Borland Builder 4:                     connector-odbc-usagenotes-apptips-borland-builder.
                                                             (line    6)
* Boundary():                            general-geometry-property-functions.
                                                             (line   70)
* brackets, square:                      data-types.         (line   40)
* brief option, mysqlaccess:             mysqlaccess.        (line   64)
* buffer sizes, client:                  connectors-apis.    (line   26)
* buffer sizes, mysqld server:           server-parameters.  (line    6)
* Buffer():                              spatial-operators.  (line   12)
* bug reports, criteria for:             bug-reports.        (line    6)
* bugs database:                         bug-reports.        (line    6)
* bugs, known:                           bugs.               (line   10)
* bugs, reporting:                       bug-reports.        (line    6)
* bugs.mysql.com:                        bug-reports.        (line    6)
* building, client programs:             building-clients.   (line    6)
* bulk_insert_buffer_size system variable: server-system-variables.
                                                             (line  710)
* burnin option, mysqlslap:              mysqlslap.          (line  249)
* C API, data types:                     c.                  (line   26)
* C API, functions:                      c-api-function-overview.
                                                             (line    6)
* C API, linking problems:               c-api-linking-problems.
                                                             (line    6)
* C prepared statement API, functions:   c-api-prepared-statement-function-overview.
                                                             (line    6)
* C++ APIs:                              apis-cplusplus.     (line    6)
* C++ Builder:                           connector-odbc-usagenotes-apptips-borland-cppbuilder.
                                                             (line    6)
* C++ compiler cannot create executables: compilation-problems.
                                                             (line   63)
* C++ compiler, gcc:                     configure-options.  (line  362)
* C:\my.cnf file:                        multiple-server-clients.
                                                             (line   34)
* CACHE INDEX:                           cache-index.        (line    6)
* CACHE INDEX, and partitioning:         partitioning-limitations.
                                                             (line  293)
* caches, clearing:                      flush.              (line    6)
* calculating, dates:                    date-calculations.  (line    6)
* calendar:                              mysql-calendar.     (line    6)
* CALL:                                  call.               (line    6)
* calling sequences for aggregate functions, UDF: udf-aggr-calling.
                                                             (line    6)
* calling sequences for simple functions, UDF: udf-calling.  (line    6)
* can't create/write to file:            cannot-create.      (line    6)
* carriage return (\r) <1>:              load-data.          (line  427)
* carriage return (\r):                  string-syntax.      (line   60)
* CASE <1>:                              case-statement.     (line    6)
* CASE:                                  control-flow-functions.
                                                             (line   12)
* case sensitivity, in access checking:  grant-table-structure.
                                                             (line  196)
* case sensitivity, in identifiers:      identifier-case-sensitivity.
                                                             (line    6)
* case sensitivity, in names:            identifier-case-sensitivity.
                                                             (line    6)
* case sensitivity, in searches:         case-sensitivity.   (line    6)
* case sensitivity, in string comparisons: string-comparison-functions.
                                                             (line   15)
* case-sensitivity, of database names:   extensions-to-ansi. (line   38)
* case-sensitivity, of table names:      extensions-to-ansi. (line   38)
* CAST:                                  cast-functions.     (line   37)
* cast functions:                        cast-functions.     (line    6)
* cast operators:                        cast-functions.     (line    6)
* casts <1>:                             cast-functions.     (line    6)
* casts <2>:                             comparison-operators.
                                                             (line   36)
* casts:                                 type-conversion.    (line    6)
* catalog-details option, mysqlbackup:   mysqlbackup.        (line   81)
* catalog-summary option, mysqlbackup:   mysqlbackup.        (line   85)
* CC environment variable <1>:           environment-variables.
                                                             (line   18)
* CC environment variable <2>:           compilation-problems.
                                                             (line  108)
* CC environment variable:               configure-options.  (line  362)
* cc1plus problems:                      compilation-problems.
                                                             (line   38)
* CEIL():                                mathematical-functions.
                                                             (line  121)
* CEILING():                             mathematical-functions.
                                                             (line  125)
* Centroid():                            multipolygon-property-functions.
                                                             (line   26)
* CFLAGS environment variable <1>:       environment-variables.
                                                             (line   18)
* CFLAGS environment variable <2>:       compilation-problems.
                                                             (line  108)
* CFLAGS environment variable:           configure-options.  (line  376)
* cflags option, mysql_config:           mysql-config.       (line   11)
* CHANGE MASTER TO:                      change-master-to.   (line    6)
* Change user, thread command:           thread-commands.    (line   13)
* ChangeLog:                             news.               (line   19)
* changes to privileges:                 privilege-changes.  (line    6)
* changes, log:                          news.               (line   19)
* changes, MySQL 5.2:                    news-5-2-x.         (line   14)
* changes, MySQL 6.0:                    news-6-0-x.         (line   21)
* Changing master, thread state:         slave-connection-thread-states.
                                                             (line    9)
* changing socket location <1>:          problems-with-mysql-sock.
                                                             (line   26)
* changing socket location <2>:          automatic-start.    (line  128)
* changing socket location:              configure-options.  (line  342)
* changing, column:                      alter-table.        (line  282)
* changing, column order:                change-column-order.
                                                             (line    6)
* changing, field:                       alter-table.        (line  282)
* changing, table <1>:                   alter-table-problems.
                                                             (line    6)
* changing, table:                       alter-table.        (line    6)
* CHAR data type <1>:                    string-types.       (line   14)
* CHAR data type:                        string-type-overview.
                                                             (line   89)
* CHAR VARYING data type:                string-type-overview.
                                                             (line  121)
* CHAR():                                string-functions.   (line  133)
* CHAR_LENGTH():                         string-functions.   (line  175)
* CHARACTER data type:                   string-type-overview.
                                                             (line   89)
* character sets:                        charset-configuration.
                                                             (line   10)
* Character sets:                        charset.            (line   22)
* character sets:                        configure-options.  (line  420)
* character sets, adding:                adding-character-set.
                                                             (line   12)
* character sets, and replication:       replication-features-charset.
                                                             (line    6)
* CHARACTER VARYING data type:           string-type-overview.
                                                             (line  121)
* character-set-client-handshake option, mysqld: server-options.
                                                             (line  188)
* character-set-filesystem option, mysqld: server-options.   (line  202)
* character-set-server option, mysqld:   server-options.     (line  218)
* character-sets-dir option, myisamchk:  myisamchk-repair-options.
                                                             (line   13)
* character-sets-dir option, myisampack: myisampack.         (line   58)
* character-sets-dir option, mysql:      mysql-command-options.
                                                             (line  165)
* character-sets-dir option, mysqladmin: mysqladmin.         (line  306)
* character-sets-dir option, mysqlbinlog: mysqlbinlog.       (line  176)
* character-sets-dir option, mysqlcheck: mysqlcheck.         (line  194)
* character-sets-dir option, mysqld:     server-options.     (line  172)
* character-sets-dir option, mysqldump:  mysqldump.          (line  298)
* character-sets-dir option, mysqlimport: mysqlimport.       (line  115)
* character-sets-dir option, mysqlshow:  mysqlshow.          (line  105)
* CHARACTER_LENGTH():                    string-functions.   (line  182)
* character_set_client system variable:  server-system-variables.
                                                             (line  738)
* character_set_connection system variable: server-system-variables.
                                                             (line  769)
* character_set_database system variable: server-system-variables.
                                                             (line  780)
* character_set_filesystem system variable: server-system-variables.
                                                             (line  796)
* character_set_results system variable: server-system-variables.
                                                             (line  821)
* character_set_server system variable:  server-system-variables.
                                                             (line  831)
* character_set_system system variable:  server-system-variables.
                                                             (line  846)
* CHARACTER_SETS, INFORMATION_SCHEMA table: character-sets-table.
                                                             (line    6)
* character_sets_dir system variable:    server-system-variables.
                                                             (line  857)
* characters, multi-byte:                multi-byte-characters.
                                                             (line    6)
* charset command, mysql:                mysql-commands.     (line   61)
* charset option, comp_err:              comp-err.           (line   30)
* CHARSET():                             information-functions.
                                                             (line   76)
* check option, myisamchk:               myisamchk-check-options.
                                                             (line    9)
* check option, mysqlcheck:              mysqlcheck.         (line  199)
* check options, myisamchk:              myisamchk-check-options.
                                                             (line    6)
* CHECK TABLE:                           check-table.        (line    6)
* CHECK TABLE, and partitioning:         partitioning-maintenance.
                                                             (line    6)
* check-only-changed option, myisamchk:  myisamchk-check-options.
                                                             (line   14)
* check-only-changed option, mysqlcheck: mysqlcheck.         (line  203)
* check-upgrade option, mysqlcheck:      mysqlcheck.         (line  208)
* Checking master version, thread state: slave-io-thread-states.
                                                             (line   20)
* checking permissions, thread state:    general-thread-states.
                                                             (line   23)
* Checking table, thread state:          general-thread-states.
                                                             (line   28)
* checking, tables for errors:           check.              (line    6)
* checkpoint option, mysqlhotcopy:       mysqlhotcopy.       (line   83)
* checksum errors:                       solaris.            (line   11)
* CHECKSUM TABLE:                        checksum-table.     (line    6)
* Chinese, Japanese, Korean character sets, frequently asked questions: faqs-cjk.
                                                             (line    6)
* choosing types:                        choosing-types.     (line    6)
* choosing, a MySQL version:             which-version.      (line   19)
* chroot option, mysqld:                 server-options.     (line  236)
* chroot option, mysqlhotcopy:           mysqlhotcopy.       (line   88)
* CJK (Chinese, Japanese, Korean), Access, PHP, etc.: faqs-cjk.
                                                             (line   48)
* CJK (Chinese, Japanese, Korean), availability of specific characters: faqs-cjk.
                                                             (line   61)
* CJK (Chinese, Japanese, Korean), available character sets: faqs-cjk.
                                                             (line   11)
* CJK (Chinese, Japanese, Korean), big5: faqs-cjk.           (line   20)
* CJK (Chinese, Japanese, Korean), character sets available: faqs-cjk.
                                                             (line   13)
* CJK (Chinese, Japanese, Korean), characters displayed as question marks: faqs-cjk.
                                                             (line   10)
* CJK (Chinese, Japanese, Korean), CJKV: faqs-cjk.           (line   78)
* CJK (Chinese, Japanese, Korean), collations: faqs-cjk.     (line   68)
* CJK (Chinese, Japanese, Korean), conversion problems with Japanese character sets: faqs-cjk.
                                                             (line   23)
* CJK (Chinese, Japanese, Korean), data truncation: faqs-cjk.
                                                             (line   44)
* CJK (Chinese, Japanese, Korean), Database and table names: faqs-cjk.
                                                             (line   82)
* CJK (Chinese, Japanese, Korean), documentation in Chinese: faqs-cjk.
                                                             (line   87)
* CJK (Chinese, Japanese, Korean), documentation in Japanese: faqs-cjk.
                                                             (line   89)
* CJK (Chinese, Japanese, Korean), documentation in Korean: faqs-cjk.
                                                             (line   89)
* CJK (Chinese, Japanese, Korean), gb2312, gbk: faqs-cjk.    (line   13)
* CJK (Chinese, Japanese, Korean), Japanese character sets: faqs-cjk.
                                                             (line   25)
* CJK (Chinese, Japanese, Korean), Korean character set: faqs-cjk.
                                                             (line   39)
* CJK (Chinese, Japanese, Korean), LIKE and FULLTEXT: faqs-cjk.
                                                             (line   58)
* CJK (Chinese, Japanese, Korean), MySQL 4.0 behavior: faqs-cjk.
                                                             (line   51)
* CJK (Chinese, Japanese, Korean), ORDER BY treatment: faqs-cjk.
                                                             (line   68)
* CJK (Chinese, Japanese, Korean), problems with Access, PHP, etc.: faqs-cjk.
                                                             (line   46)
* CJK (Chinese, Japanese, Korean), problems with Big5 character sets (Chinese): faqs-cjk.
                                                             (line   18)
* CJK (Chinese, Japanese, Korean), problems with data truncation: faqs-cjk.
                                                             (line   42)
* CJK (Chinese, Japanese, Korean), problems with euckr character set (Korean): faqs-cjk.
                                                             (line   37)
* CJK (Chinese, Japanese, Korean), problems with GB character sets (Chinese): faqs-cjk.
                                                             (line   13)
* CJK (Chinese, Japanese, Korean), problems with LIKE and FULLTEXT: faqs-cjk.
                                                             (line   56)
* CJK (Chinese, Japanese, Korean), problems with Yen sign (Japanese): faqs-cjk.
                                                             (line   30)
* CJK (Chinese, Japanese, Korean), rejected characters: faqs-cjk.
                                                             (line   74)
* CJK (Chinese, Japanese, Korean), sort order problems: faqs-cjk.
                                                             (line   68)
* CJK (Chinese, Japanese, Korean), sorting problems: faqs-cjk.
                                                             (line   66)
* CJK (Chinese, Japanese, Korean), testing availability of characters: faqs-cjk.
                                                             (line   63)
* CJK (Chinese, Japanese, Korean), Unicode collations: faqs-cjk.
                                                             (line   72)
* CJK (Chinese, Japanese, Korean), Vietnamese: faqs-cjk.     (line   80)
* CJK (Chinese, Japanese, Korean), Yen sign: faqs-cjk.       (line   32)
* CJK, FAQ:                              faqs-cjk.           (line    6)
* cleaning up, thread state:             general-thread-states.
                                                             (line   32)
* clear command, mysql:                  mysql-commands.     (line   69)
* clearing, caches:                      flush.              (line    6)
* Clearing, thread state:                event-scheduler-thread-states.
                                                             (line   10)
* client connection threads:             connection-threads. (line    6)
* client programs:                       programs-overview.  (line  111)
* client programs, building:             building-clients.   (line    6)
* client tools:                          connectors-apis.    (line   26)
* clients, debugging:                    debugging-client.   (line    6)
* clients, threaded:                     threaded-clients.   (line    6)
* CLOSE:                                 close.              (line    6)
* Close stmt, thread command:            thread-commands.    (line   17)
* closing tables, thread state:          general-thread-states.
                                                             (line   37)
* closing, tables:                       table-cache.        (line    6)
* clustered index, InnoDB:               innodb-index-types. (line    6)
* CMake:                                 windows-source-build-cmake.
                                                             (line    6)
* COALESCE():                            comparison-operators.
                                                             (line  210)
* COERCIBILITY():                        information-functions.
                                                             (line   87)
* ColdFusion:                            connector-odbc-usagenotes-apptips-coldfusion.
                                                             (line    6)
* collating, strings:                    string-collating.   (line    6)
* COLLATION():                           information-functions.
                                                             (line  113)
* collation, adding:                     adding-collation.   (line   13)
* collation-server option, mysqld:       server-options.     (line  250)
* COLLATION_CHARACTER_SET_APPLICABILITY, INFORMATION_SCHEMA table: collation-character-set-applicability-table.
                                                             (line    6)
* collation_connection system variable:  server-system-variables.
                                                             (line  872)
* collation_database system variable:    server-system-variables.
                                                             (line  882)
* collation_server system variable:      server-system-variables.
                                                             (line  898)
* COLLATIONS, INFORMATION_SCHEMA table:  collations-table.   (line    6)
* column comments:                       create-table.       (line  317)
* column names, case sensitivity:        identifier-case-sensitivity.
                                                             (line    6)
* column, changing:                      alter-table.        (line  282)
* column, types:                         data-types.         (line   29)
* column-names option, mysql:            mysql-command-options.
                                                             (line  170)
* column-type-info option, mysql:        mysql-command-options.
                                                             (line  174)
* COLUMN_PRIVILEGES, INFORMATION_SCHEMA table: column-privileges-table.
                                                             (line    6)
* columns option, mysqlimport:           mysqlimport.        (line  120)
* columns, changing:                     change-column-order.
                                                             (line    6)
* columns, displaying:                   mysqlshow.          (line    6)
* columns, indexes:                      indexes.            (line    6)
* COLUMNS, INFORMATION_SCHEMA table:     columns-table.      (line    6)
* columns, names:                        identifiers.        (line   13)
* columns, other types:                  other-vendor-data-types.
                                                             (line    6)
* columns, selecting:                    selecting-columns.  (line    6)
* columns, storage requirements:         storage-requirements.
                                                             (line    6)
* comma-separated values data, reading <1>: select.          (line  381)
* comma-separated values data, reading:  load-data.          (line  310)
* command options, mysql:                mysql-command-options.
                                                             (line    6)
* command options, mysqladmin:           mysqladmin.         (line  232)
* command options, mysqld:               server-options.     (line    6)
* command syntax <1>:                    mem-conventions.    (line  102)
* command syntax:                        manual-conventions. (line  112)
* command-line history, mysql:           mysql-command-options.
                                                             (line  562)
* command-line tool:                     mysql.              (line   14)
* commands out of sync:                  commands-out-of-sync.
                                                             (line    6)
* commands, for binary distribution:     installing-binary.  (line   39)
* Comment syntax:                        comments.           (line    6)
* comments option, mysql:                mysql-command-options.
                                                             (line  178)
* comments option, mysqldump:            mysqldump.          (line  303)
* comments, adding:                      comments.           (line    6)
* comments, starting:                    ansi-diff-comments. (line    6)
* COMMIT <1>:                            commit.             (line    6)
* COMMIT:                                ansi-diff-transactions.
                                                             (line    6)
* commit option, mysqlaccess:            mysqlaccess.        (line   68)
* commit option, mysqlslap:              mysqlslap.          (line  254)
* COMMIT, XA transactions:               xa-statements.      (line    6)
* comp_err <1>:                          comp-err.           (line    6)
* comp_err:                              programs-overview.  (line   64)
* comp_err, charset option:              comp-err.           (line   30)
* comp_err, debug option:                comp-err.           (line   35)
* comp_err, debug-info option:           comp-err.           (line   40)
* comp_err, header_file option:          comp-err.           (line   44)
* comp_err, help option:                 comp-err.           (line   26)
* comp_err, in_file option:              comp-err.           (line   48)
* comp_err, name_file option:            comp-err.           (line   53)
* comp_err, out_dir option:              comp-err.           (line   57)
* comp_err, out_file option:             comp-err.           (line   62)
* comp_err, statefile option:            comp-err.           (line   66)
* comp_err, version option:              comp-err.           (line   71)
* compact option, mysqldump:             mysqldump.          (line  310)
* comparison operators:                  comparison-operators.
                                                             (line    6)
* compatibility, between MySQL versions: upgrading-from-5-1. (line    6)
* compatibility, with mSQL:              regexp.             (line   30)
* compatibility, with ODBC <1>:          join.               (line  145)
* compatibility, with ODBC <2>:          create-table.       (line  274)
* compatibility, with ODBC <3>:          comparison-operators.
                                                             (line  151)
* compatibility, with ODBC <4>:          type-conversion.    (line   40)
* compatibility, with ODBC <5>:          numeric-type-overview.
                                                             (line  230)
* compatibility, with ODBC:              identifier-qualifiers.
                                                             (line   41)
* compatibility, with Oracle <1>:        describe.           (line   32)
* compatibility, with Oracle <2>:        group-by-functions. (line  227)
* compatibility, with Oracle:            extensions-to-ansi. (line   96)
* compatibility, with PostgreSQL:        extensions-to-ansi. (line  194)
* compatibility, with standard SQL:      compatibility.      (line   15)
* compatibility, with Sybase:            use.                (line   27)
* compatible option, mysqldump:          mysqldump.          (line  316)
* compiler, C++ gcc:                     configure-options.  (line  362)
* compiling, on Windows:                 windows-client-compiling.
                                                             (line    6)
* compiling, optimizing:                 system-optimization.
                                                             (line    6)
* compiling, problems:                   compilation-problems.
                                                             (line    6)
* compiling, speed:                      compile-and-link-options.
                                                             (line    6)
* compiling, statically:                 configure-options.  (line  354)
* compiling, user-defined functions:     udf-compiling.      (line    6)
* complete-insert option, mysqldump:     mysqldump.          (line  336)
* completion_type system variable:       server-system-variables.
                                                             (line  913)
* compliance, Y2K:                       y2k-issues.         (line    6)
* composite partitioning:                partitioning-subpartitions.
                                                             (line   26)
* compound statements:                   sql-syntax-compound-statements.
                                                             (line   17)
* compress option, mysql:                mysql-command-options.
                                                             (line  185)
* compress option, mysqladmin:           mysqladmin.         (line  311)
* compress option, mysqlcheck:           mysqlcheck.         (line  215)
* compress option, mysqldump:            mysqldump.          (line  341)
* compress option, mysqlimport:          mysqlimport.        (line  126)
* compress option, mysqlshow:            mysqlshow.          (line  110)
* compress option, mysqlslap:            mysqlslap.          (line  259)
* COMPRESS():                            encryption-functions.
                                                             (line   82)
* compressed tables <1>:                 compressed-format.  (line    6)
* compressed tables:                     myisampack.         (line    6)
* CONCAT():                              string-functions.   (line  186)
* CONCAT_WS():                           string-functions.   (line  213)
* concatenation, string <1>:             string-functions.   (line  186)
* concatenation, string:                 string-syntax.      (line   12)
* concurrency option, mysqlslap:         mysqlslap.          (line  264)
* concurrent inserts <1>:                concurrent-inserts. (line    6)
* concurrent inserts:                    internal-locking.   (line   71)
* concurrent_insert system variable:     server-system-variables.
                                                             (line  944)
* Conditions:                            declare-condition.  (line    6)
* config-file option, my_print_defaults: my-print-defaults.  (line   29)
* config-file option, mysqld_multi:      mysqld-multi.       (line   80)
* config.cache:                          compilation-problems.
                                                             (line   15)
* config.cache file:                     compilation-problems.
                                                             (line    6)
* configuration files:                   access-denied.      (line  108)
* configuration options:                 configure-options.  (line    6)
* configure option, -with-low-memory:    compilation-problems.
                                                             (line   38)
* configure script:                      configure-options.  (line    6)
* configure, disable-grant-options option: configure-options.
                                                             (line  542)
* configure, enable-community-features option: configure-options.
                                                             (line  557)
* configure, enable-debug-sync option:   configure-options.  (line  489)
* configure, enable-dtrace option:       configure-options.  (line  509)
* configure, enable-profiling option:    configure-options.  (line  563)
* configure, enable-thread-safe-client option: configure-options.
                                                             (line  516)
* configure, localstatedir option:       configure-options.  (line  321)
* configure, prefix option:              configure-options.  (line  321)
* configure, running after prior invocation: compilation-problems.
                                                             (line   15)
* configure, with-big-tables option:     configure-options.  (line  532)
* configure, with-charset option:        configure-options.  (line  420)
* configure, with-client-ldflags option: configure-options.  (line  354)
* configure, with-collation option:      configure-options.  (line  420)
* configure, with-debug option:          configure-options.  (line  472)
* configure, with-embedded-server option: configure-options. (line  318)
* configure, with-extra-charsets option: configure-options.  (line  420)
* configure, with-libevent option:       configure-options.  (line  548)
* configure, with-unix-socket-path option: configure-options.
                                                             (line  342)
* configure, with-zlib-dir option:       configure-options.  (line  522)
* configure, without-server option:      configure-options.  (line  304)
* connect command, mysql:                mysql-commands.     (line   74)
* Connect Out, thread command:           thread-commands.    (line   25)
* Connect, thread command:               thread-commands.    (line   21)
* connect_timeout system variable:       server-system-variables.
                                                             (line  980)
* connect_timeout variable <1>:          mysqladmin.         (line  437)
* connect_timeout variable:              mysql-command-options.
                                                             (line  537)
* Connecting to master, thread state:    slave-io-thread-states.
                                                             (line   16)
* connecting, remotely with SSH:         windows-and-ssh.    (line    6)
* connecting, to the server <1>:         connecting.         (line    6)
* connecting, to the server:             connecting-disconnecting.
                                                             (line    6)
* connecting, verification:              connection-access.  (line    6)
* connection, aborted:                   communication-errors.
                                                             (line    6)
* CONNECTION_ID():                       information-functions.
                                                             (line  122)
* Connector/C:                           connectors-apis.    (line   26)
* Connector/C++:                         connectors-apis.    (line   26)
* Connector/JDBC:                        connectors-apis.    (line   26)
* Connector/MXJ:                         connectors-apis.    (line   26)
* Connector/NET <1>:                     connector-net.      (line   15)
* Connector/NET:                         connectors-apis.    (line   26)
* Connector/NET, reporting problems:     connect-net-support.
                                                             (line   12)
* Connector/ODBC <1>:                    connector-odbc.     (line   17)
* Connector/ODBC:                        connectors-apis.    (line   26)
* Connector/ODBC, Borland:               connector-odbc-usagenotes-apptips-borland.
                                                             (line   12)
* Connector/ODBC, Borland Database Engine: connector-odbc-usagenotes-apptips-borland.
                                                             (line   12)
* Connector/ODBC, reporting problems:    connector-odbc-support.
                                                             (line   14)
* Connector/OpenOffice.org:              connectors-apis.    (line   26)
* Connectors, MySQL:                     connectors-apis.    (line   26)
* console option, mysqld:                server-options.     (line  266)
* const table, optimizer <1>:            select.             (line  472)
* const table, optimizer:                using-explain.      (line  134)
* constant table:                        where-optimizations.
                                                             (line   50)
* constraints:                           constraints.        (line   12)
* CONSTRAINTS, INFORMATION_SCHEMA table: table-constraints-table.
                                                             (line    6)
* Contains():                            functions-that-test-spatial-relationships-between-geometries.
                                                             (line   21)
* contributing companies, list of:       supporters.         (line    6)
* contributors, list of:                 contributors.       (line    6)
* control flow functions:                control-flow-functions.
                                                             (line    6)
* CONV():                                mathematical-functions.
                                                             (line  138)
* conventions, syntax:                   manual-conventions. (line    8)
* conventions, typographical <1>:        mem-conventions.    (line    8)
* conventions, typographical:            manual-conventions. (line    8)
* CONVERT:                               cast-functions.     (line   43)
* CONVERT TO:                            alter-table.        (line  430)
* CONVERT_TZ():                          date-and-time-functions.
                                                             (line  158)
* converting HEAP to MyISAM, thread state: general-thread-states.
                                                             (line   44)
* ConvexHull():                          spatial-operators.  (line   17)
* copy option, mysqlaccess:              mysqlaccess.        (line   75)
* copy to tmp table, thread state:       general-thread-states.
                                                             (line   49)
* copying databases:                     copying-databases.  (line    6)
* copying tables:                        create-table.       (line 1103)
* Copying to group table, thread state:  general-thread-states.
                                                             (line   55)
* Copying to tmp table on disk, thread state: general-thread-states.
                                                             (line   64)
* Copying to tmp table, thread state:    general-thread-states.
                                                             (line   60)
* core-file option, mysqld:              server-options.     (line  279)
* core-file-size option, mysqld_safe:    mysqld-safe.        (line  119)
* correct-checksum option, myisamchk:    myisamchk-repair-options.
                                                             (line   18)
* correlated subqueries:                 correlated-subqueries.
                                                             (line    6)
* COS():                                 mathematical-functions.
                                                             (line  158)
* COT():                                 mathematical-functions.
                                                             (line  165)
* count option, myisam_ftdump:           myisam-ftdump.      (line   52)
* count option, mysqladmin:              mysqladmin.         (line  316)
* count option, mysqlshow:               mysqlshow.          (line  115)
* COUNT():                               group-by-functions. (line   89)
* COUNT(DISTINCT):                       group-by-functions. (line  119)
* counting, table rows:                  counting-rows.      (line    6)
* CR_SERVER_GONE_ERROR:                  gone-away.          (line    6)
* CR_SERVER_LOST_ERROR:                  gone-away.          (line    6)
* crash:                                 debugging-server.   (line   16)
* crash, recovery:                       crash-recovery.     (line    6)
* crash, repeated:                       crashing.           (line    6)
* crash, replication:                    replication-features-mastercrash.
                                                             (line    6)
* crash-me:                              mysql-benchmarks.   (line   43)
* crash-me program <1>:                  mysql-benchmarks.   (line    6)
* crash-me program:                      portability.        (line    6)
* CRC32():                               mathematical-functions.
                                                             (line  174)
* CREATE DATABASE:                       create-database.    (line    6)
* Create DB, thread command:             thread-commands.    (line   29)
* CREATE EVENT:                          create-event.       (line    6)
* CREATE FUNCTION <1>:                   create-function-udf.
                                                             (line    6)
* CREATE FUNCTION:                       create-procedure.   (line    6)
* CREATE INDEX:                          create-index.       (line    6)
* create option, mysqlslap:              mysqlslap.          (line  269)
* CREATE PROCEDURE:                      create-procedure.   (line    6)
* CREATE SCHEMA:                         create-database.    (line    6)
* CREATE SERVER:                         create-server.      (line    6)
* CREATE TABLE:                          create-table.       (line   10)
* CREATE TABLE ... SELECT, and replication: replication-features-create-select.
                                                             (line    6)
* CREATE TABLE, DIRECTORY options, and replication: replication-features-directory.
                                                             (line    6)
* CREATE TRIGGER:                        create-trigger.     (line    6)
* CREATE USER:                           create-user.        (line    6)
* CREATE VIEW:                           create-view.        (line    6)
* create-options option, mysqldump:      mysqldump.          (line  346)
* create-schema option, mysqlslap:       mysqlslap.          (line  274)
* Creating delayed handler, thread state: delayed-insert-thread-states.
                                                             (line   22)
* Creating index, thread state:          general-thread-states.
                                                             (line   71)
* Creating sort index, thread state:     general-thread-states.
                                                             (line   76)
* creating table, thread state:          general-thread-states.
                                                             (line   81)
* Creating tmp table, thread state:      general-thread-states.
                                                             (line   86)
* creating user accounts:                create-user.        (line    6)
* creating, bug reports:                 bug-reports.        (line    6)
* creating, database:                    create-database.    (line    6)
* creating, databases:                   database-use.       (line   13)
* creating, default startup options:     option-files.       (line   11)
* creating, function:                    create-function-udf.
                                                             (line    6)
* creating, schema:                      create-database.    (line    6)
* creating, tables:                      creating-tables.    (line    6)
* CROSS JOIN:                            join.               (line    6)
* Crosses():                             functions-that-test-spatial-relationships-between-geometries.
                                                             (line   26)
* CSV data, reading <1>:                 select.             (line  381)
* CSV data, reading:                     load-data.          (line  310)
* csv option, mysqlslap:                 mysqlslap.          (line  278)
* CSV storage engine <1>:                csv-storage-engine. (line   11)
* CSV storage engine:                    storage-engines.    (line   24)
* CURDATE():                             date-and-time-functions.
                                                             (line  182)
* CURRENT_DATE:                          date-and-time-functions.
                                                             (line  193)
* CURRENT_TIME:                          date-and-time-functions.
                                                             (line  209)
* CURRENT_TIMESTAMP:                     date-and-time-functions.
                                                             (line  213)
* CURRENT_USER():                        information-functions.
                                                             (line  131)
* Cursors:                               cursors.            (line   13)
* CURTIME():                             date-and-time-functions.
                                                             (line  197)
* customers, of MySQL:                   internal-use.       (line    6)
* CXX environment variable <1>:          environment-variables.
                                                             (line   18)
* CXX environment variable <2>:          compilation-problems.
                                                             (line   66)
* CXX environment variable:              configure-options.  (line  362)
* CXXFLAGS environment variable <1>:     environment-variables.
                                                             (line   18)
* CXXFLAGS environment variable <2>:     compilation-problems.
                                                             (line  108)
* CXXFLAGS environment variable:         configure-options.  (line  376)
* Daemon, thread command:                thread-commands.    (line   33)
* DATA DIRECTORY, and replication:       replication-features-directory.
                                                             (line    6)
* Data truncation with CJK characters:   faqs-cjk.           (line   44)
* data type, BIGINT:                     numeric-type-overview.
                                                             (line  127)
* data type, BINARY <1>:                 binary-varbinary.   (line    6)
* data type, BINARY:                     string-type-overview.
                                                             (line  151)
* data type, BIT:                        numeric-type-overview.
                                                             (line   35)
* data type, BLOB <1>:                   blob.               (line    6)
* data type, BLOB:                       string-type-overview.
                                                             (line  180)
* data type, BOOL <1>:                   other-vendor-data-types.
                                                             (line    6)
* data type, BOOL:                       numeric-type-overview.
                                                             (line   45)
* data type, BOOLEAN <1>:                other-vendor-data-types.
                                                             (line    6)
* data type, BOOLEAN:                    numeric-type-overview.
                                                             (line   45)
* data type, CHAR <1>:                   string-types.       (line   14)
* data type, CHAR:                       string-type-overview.
                                                             (line   89)
* data type, CHAR VARYING:               string-type-overview.
                                                             (line  121)
* data type, CHARACTER:                  string-type-overview.
                                                             (line   89)
* data type, CHARACTER VARYING:          string-type-overview.
                                                             (line  121)
* data type, DATE <1>:                   datetime.           (line   10)
* data type, DATE:                       date-and-time-type-overview.
                                                             (line   16)
* data type, DATETIME <1>:               datetime.           (line   10)
* data type, DATETIME:                   date-and-time-type-overview.
                                                             (line   23)
* data type, DEC:                        numeric-type-overview.
                                                             (line  248)
* data type, DECIMAL <1>:                precision-math.     (line   14)
* data type, DECIMAL:                    numeric-type-overview.
                                                             (line  232)
* data type, DOUBLE:                     numeric-type-overview.
                                                             (line  192)
* data type, DOUBLE PRECISION:           numeric-type-overview.
                                                             (line  209)
* data type, ENUM <1>:                   enum.               (line    6)
* data type, ENUM:                       string-type-overview.
                                                             (line  239)
* data type, FIXED:                      numeric-type-overview.
                                                             (line  248)
* data type, FLOAT:                      numeric-type-overview.
                                                             (line  172)
* data type, GEOMETRY:                   mysql-spatial-datatypes.
                                                             (line    6)
* data type, GEOMETRYCOLLECTION:         mysql-spatial-datatypes.
                                                             (line    6)
* data type, INT:                        numeric-type-overview.
                                                             (line  118)
* data type, INTEGER:                    numeric-type-overview.
                                                             (line  123)
* data type, LINESTRING:                 mysql-spatial-datatypes.
                                                             (line    6)
* data type, LONG:                       blob.               (line    6)
* data type, LONGBLOB:                   string-type-overview.
                                                             (line  218)
* data type, LONGTEXT:                   string-type-overview.
                                                             (line  228)
* data type, MEDIUMBLOB:                 string-type-overview.
                                                             (line  203)
* data type, MEDIUMINT:                  numeric-type-overview.
                                                             (line  113)
* data type, MEDIUMTEXT:                 string-type-overview.
                                                             (line  210)
* data type, MULTILINESTRING:            mysql-spatial-datatypes.
                                                             (line    6)
* data type, MULTIPOINT:                 mysql-spatial-datatypes.
                                                             (line    6)
* data type, MULTIPOLYGON:               mysql-spatial-datatypes.
                                                             (line    6)
* data type, NATIONAL CHAR:              string-type-overview.
                                                             (line   89)
* data type, NATIONAL VARCHAR:           string-type-overview.
                                                             (line  121)
* data type, NCHAR:                      string-type-overview.
                                                             (line   89)
* data type, NUMERIC:                    numeric-type-overview.
                                                             (line  248)
* data type, NVARCHAR:                   string-type-overview.
                                                             (line  121)
* data type, POINT:                      mysql-spatial-datatypes.
                                                             (line    6)
* data type, POLYGON:                    mysql-spatial-datatypes.
                                                             (line    6)
* data type, REAL:                       numeric-type-overview.
                                                             (line  209)
* data type, SET <1>:                    set.                (line    6)
* data type, SET:                        string-type-overview.
                                                             (line  248)
* data type, SMALLINT:                   numeric-type-overview.
                                                             (line  108)
* data type, TEXT <1>:                   blob.               (line    6)
* data type, TEXT:                       string-type-overview.
                                                             (line  191)
* data type, TIME <1>:                   time.               (line    6)
* data type, TIME:                       date-and-time-type-overview.
                                                             (line   63)
* data type, TIMESTAMP <1>:              datetime.           (line   10)
* data type, TIMESTAMP:                  date-and-time-type-overview.
                                                             (line   31)
* data type, TINYBLOB:                   string-type-overview.
                                                             (line  165)
* data type, TINYINT:                    numeric-type-overview.
                                                             (line   40)
* data type, TINYTEXT:                   string-type-overview.
                                                             (line  172)
* data type, VARBINARY <1>:              binary-varbinary.   (line    6)
* data type, VARBINARY:                  string-type-overview.
                                                             (line  158)
* data type, VARCHAR <1>:                string-types.       (line   14)
* data type, VARCHAR:                    string-type-overview.
                                                             (line  121)
* data type, VARCHARACTER:               string-type-overview.
                                                             (line  121)
* data type, YEAR <1>:                   year.               (line    6)
* data type, YEAR:                       date-and-time-type-overview.
                                                             (line   70)
* data types:                            data-types.         (line   29)
* data types, C API:                     c.                  (line   26)
* data types, overview:                  data-type-overview. (line   13)
* data, character sets:                  charset-configuration.
                                                             (line   10)
* data, importing <1>:                   mysqlimport.        (line    6)
* data, importing:                       batch-commands.     (line    6)
* data, loading into tables:             loading-tables.     (line    6)
* data, retrieving:                      retrieving-data.    (line   18)
* data, size:                            data-size.          (line    6)
* data-chunks option, mysqlbackup:       mysqlbackup.        (line   89)
* data-file-length option, myisamchk:    myisamchk-repair-options.
                                                             (line   22)
* data-totals option, mysqlbackup:       mysqlbackup.        (line   94)
* database design:                       design.             (line    6)
* Database information, obtaining:       show.               (line   49)
* database metadata:                     information-schema. (line   39)
* database names, case sensitivity:      identifier-case-sensitivity.
                                                             (line    6)
* database names, case-sensitivity:      extensions-to-ansi. (line   38)
* database option, mysql:                mysql-command-options.
                                                             (line  190)
* database option, mysqlbinlog:          mysqlbinlog.        (line  181)
* DATABASE():                            information-functions.
                                                             (line  162)
* database, altering:                    alter-database.     (line    6)
* database, creating:                    create-database.    (line    6)
* database, deleting:                    drop-database.      (line    6)
* databases option, mysqlcheck:          mysqlcheck.         (line  220)
* databases option, mysqldump:           mysqldump.          (line  351)
* databases, backups:                    backup-and-recovery.
                                                             (line   14)
* databases, copying:                    copying-databases.  (line    6)
* databases, creating:                   database-use.       (line   13)
* databases, defined:                    what-is-mysql.      (line   28)
* databases, displaying:                 mysqlshow.          (line    6)
* databases, dumping <1>:                mysqlhotcopy.       (line    6)
* databases, dumping:                    mysqldump.          (line    6)
* databases, information about:          getting-information.
                                                             (line    6)
* databases, names:                      identifiers.        (line   13)
* databases, replicating:                replication.        (line   13)
* databases, selecting:                  creating-database.  (line    6)
* databases, symbolic links:             symbolic-links-to-databases.
                                                             (line    6)
* databases, using:                      database-use.       (line   13)
* datadir option, mysql.server:          mysql-server.       (line   40)
* datadir option, mysql_install_db:      mysql-install-db.   (line   52)
* datadir option, mysql_upgrade:         mysql-upgrade.      (line   94)
* datadir option, mysqld:                server-options.     (line  305)
* datadir option, mysqld_safe:           mysqld-safe.        (line  124)
* datadir system variable:               server-system-variables.
                                                             (line 1002)
* DataJunction:                          connector-odbc-usagenotes-apptips-datajunction.
                                                             (line    6)
* DATE:                                  using-date.         (line    6)
* date and time functions:               date-and-time-functions.
                                                             (line    6)
* Date and Time types:                   date-and-time-types.
                                                             (line   13)
* date calculations:                     date-calculations.  (line    6)
* DATE columns, problems:                using-date.         (line    6)
* DATE data type <1>:                    datetime.           (line   10)
* DATE data type:                        date-and-time-type-overview.
                                                             (line   16)
* date functions, Y2K compliance:        y2k-issues.         (line    6)
* date types:                            storage-requirements.
                                                             (line   57)
* date types, Y2K issues:                y2k-issues.         (line    6)
* date values, problems:                 datetime.           (line  166)
* DATE():                                date-and-time-functions.
                                                             (line  218)
* DATE_ADD():                            date-and-time-functions.
                                                             (line  237)
* date_format system variable:           server-system-variables.
                                                             (line 1018)
* DATE_FORMAT():                         date-and-time-functions.
                                                             (line  394)
* DATE_SUB():                            date-and-time-functions.
                                                             (line  237)
* DATEDIFF():                            date-and-time-functions.
                                                             (line  225)
* dates, used with partitioning:         partitioning-types. (line   39)
* dates, used with partitioning (examples) <1>: partitioning-pruning.
                                                             (line   71)
* dates, used with partitioning (examples) <2>: partitioning-subpartitions.
                                                             (line   30)
* dates, used with partitioning (examples) <3>: partitioning-hash.
                                                             (line   49)
* dates, used with partitioning (examples): partitioning-range.
                                                             (line  126)
* DATETIME data type <1>:                datetime.           (line   10)
* DATETIME data type:                    date-and-time-type-overview.
                                                             (line   23)
* datetime_format system variable:       server-system-variables.
                                                             (line 1022)
* DAY():                                 date-and-time-functions.
                                                             (line  478)
* DAYNAME():                             date-and-time-functions.
                                                             (line  482)
* DAYOFMONTH():                          date-and-time-functions.
                                                             (line  491)
* DAYOFWEEK():                           date-and-time-functions.
                                                             (line  500)
* DAYOFYEAR():                           date-and-time-functions.
                                                             (line  509)
* db option, mysqlaccess:                mysqlaccess.        (line   79)
* db table, sorting:                     request-access.     (line   52)
* DB2 SQL mode:                          server-sql-mode.    (line  447)
* DBI interface:                         apis-perl.          (line    6)
* DBI->quote:                            string-syntax.      (line  140)
* DBI->trace:                            using-gdb-on-mysqld.
                                                             (line   89)
* DBI/DBD interface:                     apis-perl.          (line    6)
* DBI_TRACE environment variable <1>:    using-gdb-on-mysqld.
                                                             (line   89)
* DBI_TRACE environment variable:        environment-variables.
                                                             (line   18)
* DBI_USER environment variable:         environment-variables.
                                                             (line   18)
* DBUG package:                          the-dbug-package.   (line    6)
* DEALLOCATE PREPARE <1>:                deallocate-prepare. (line    6)
* DEALLOCATE PREPARE:                    sql-syntax-prepared-statements.
                                                             (line   13)
* debug option, comp_err:                comp-err.           (line   35)
* debug option, make_win_bin_dist:       make-win-bin-dist.  (line   37)
* debug option, my_print_defaults:       my-print-defaults.  (line   35)
* debug option, myisamchk:               myisamchk-general-options.
                                                             (line   21)
* debug option, myisampack:              myisampack.         (line   63)
* debug option, mysql:                   mysql-command-options.
                                                             (line  194)
* debug option, mysqlaccess:             mysqlaccess.        (line   83)
* debug option, mysqladmin:              mysqladmin.         (line  321)
* debug option, mysqlbackup:             mysqlbackup.        (line   99)
* debug option, mysqlbinlog:             mysqlbinlog.        (line  193)
* debug option, mysqlcheck:              mysqlcheck.         (line  228)
* debug option, mysqld:                  server-options.     (line  320)
* debug option, mysqldump:               mysqldump.          (line  360)
* debug option, mysqldumpslow:           mysqldumpslow.      (line   52)
* debug option, mysqlhotcopy:            mysqlhotcopy.       (line   94)
* debug option, mysqlimport:             mysqlimport.        (line  131)
* debug option, mysqlshow:               mysqlshow.          (line  120)
* debug option, mysqlslap:               mysqlslap.          (line  283)
* debug system variable:                 server-system-variables.
                                                             (line 1026)
* Debug, thread command:                 thread-commands.    (line   38)
* debug-check option, mysql:             mysql-command-options.
                                                             (line  199)
* debug-check option, mysql_upgrade:     mysql-upgrade.      (line   98)
* debug-check option, mysqladmin:        mysqladmin.         (line  327)
* debug-check option, mysqlbinlog:       mysqlbinlog.        (line  199)
* debug-check option, mysqlcheck:        mysqlcheck.         (line  233)
* debug-check option, mysqldump:         mysqldump.          (line  366)
* debug-check option, mysqlimport:       mysqlimport.        (line  136)
* debug-check option, mysqlshow:         mysqlshow.          (line  125)
* debug-check option, mysqlslap:         mysqlslap.          (line  289)
* debug-info option, comp_err:           comp-err.           (line   40)
* debug-info option, mysql:              mysql-command-options.
                                                             (line  203)
* debug-info option, mysql_upgrade:      mysql-upgrade.      (line  102)
* debug-info option, mysqladmin:         mysqladmin.         (line  331)
* debug-info option, mysqlbinlog:        mysqlbinlog.        (line  203)
* debug-info option, mysqlcheck:         mysqlcheck.         (line  237)
* debug-info option, mysqldump:          mysqldump.          (line  370)
* debug-info option, mysqlimport:        mysqlimport.        (line  140)
* debug-info option, mysqlshow:          mysqlshow.          (line  129)
* debug-info option, mysqlslap:          mysqlslap.          (line  293)
* debug-sync-timeout option, mysqld:     server-options.     (line  349)
* debug_sync system variable:            server-system-variables.
                                                             (line 1072)
* debugging support:                     configure-options.  (line    6)
* debugging, client:                     debugging-client.   (line    6)
* debugging, server:                     debugging-server.   (line   16)
* DEC data type:                         numeric-type-overview.
                                                             (line  248)
* decimal arithmetic:                    precision-math.     (line   14)
* DECIMAL data type <1>:                 precision-math.     (line   14)
* DECIMAL data type:                     numeric-type-overview.
                                                             (line  232)
* decimal point:                         data-types.         (line   36)
* DECLARE:                               declare.            (line    6)
* DECODE():                              encryption-functions.
                                                             (line  115)
* decode_bits myisamchk variable:        myisamchk-general-options.
                                                             (line   53)
* default host name:                     connecting.         (line    6)
* default installation location:         installation-layouts.
                                                             (line    6)
* default options:                       option-files.       (line   11)
* DEFAULT value clause <1>:              create-table.       (line  296)
* DEFAULT value clause:                  data-type-defaults. (line    6)
* default values <1>:                    insert.             (line   70)
* default values <2>:                    create-table.       (line  296)
* default values <3>:                    data-type-defaults. (line    6)
* default values:                        design-limitations. (line   20)
* default values, BLOB and TEXT columns: blob.               (line   55)
* default values, explicit:              data-type-defaults. (line    6)
* default values, implicit:              data-type-defaults. (line    6)
* default values, suppression:           constraint-invalid-data.
                                                             (line    6)
* DEFAULT():                             miscellaneous-functions.
                                                             (line   27)
* DEFAULT, constraint:                   constraint-invalid-data.
                                                             (line    6)
* default, privileges:                   default-privileges. (line    6)
* default-character-set option, mysql:   mysql-command-options.
                                                             (line  208)
* default-character-set option, mysqladmin: mysqladmin.      (line  336)
* default-character-set option, mysqlcheck: mysqlcheck.      (line  242)
* default-character-set option, mysqld:  server-options.     (line  374)
* default-character-set option, mysqldump: mysqldump.        (line  375)
* default-character-set option, mysqlimport: mysqlimport.    (line  145)
* default-character-set option, mysqlshow: mysqlshow.        (line  134)
* default-collation option, mysqld:      server-options.     (line  387)
* default-storage-engine option, mysqld: server-options.     (line  402)
* default-table-type option, mysqld:     server-options.     (line  411)
* default-time-zone option, mysqld:      server-options.     (line  424)
* default_week_format system variable:   server-system-variables.
                                                             (line 1106)
* defaults, embedded:                    libmysqld-options.  (line    6)
* defaults-extra-file option:            option-file-options.
                                                             (line   15)
* defaults-extra-file option, my_print_defaults: my-print-defaults.
                                                             (line   41)
* defaults-extra-file option, mysqld_multi: mysqld-multi.    (line   66)
* defaults-extra-file option, mysqld_safe: mysqld-safe.      (line  128)
* defaults-file option:                  option-file-options.
                                                             (line   22)
* defaults-file option, my_print_defaults: my-print-defaults.
                                                             (line   31)
* defaults-file option, mysqld_multi:    mysqld-multi.       (line   64)
* defaults-file option, mysqld_safe:     mysqld-safe.        (line  135)
* defaults-group-suffix option:          option-file-options.
                                                             (line   28)
* defaults-group-suffix option, my_print_defaults: my-print-defaults.
                                                             (line   48)
* DEGREES():                             mathematical-functions.
                                                             (line  186)
* delay-key-write option, mysqld <1>:    myisam-start.       (line   38)
* delay-key-write option, mysqld:        server-options.     (line  437)
* delay_key_write system variable:       server-system-variables.
                                                             (line 1123)
* DELAYED:                               insert-delayed.     (line    6)
* Delayed insert, thread command:        thread-commands.    (line   42)
* delayed inserts, thread states:        delayed-insert-thread-states.
                                                             (line    6)
* DELAYED, when ignored:                 insert.             (line  226)
* delayed-insert option, mysqldump:      mysqldump.          (line  385)
* delayed-start option, mysqlslap:       mysqlslap.          (line  303)
* delayed_insert_limit:                  insert-delayed.     (line  122)
* delayed_insert_limit system variable:  server-system-variables.
                                                             (line 1163)
* delayed_insert_timeout system variable: server-system-variables.
                                                             (line 1189)
* delayed_queue_size system variable:    server-system-variables.
                                                             (line 1207)
* DELETE:                                delete.             (line    6)
* delete option, mysqlimport:            mysqlimport.        (line  150)
* delete-master-logs option, mysqldump:  mysqldump.          (line  390)
* deleting from main table, thread state: general-thread-states.
                                                             (line   93)
* deleting from reference tables, thread state: general-thread-states.
                                                             (line   99)
* deleting, database:                    drop-database.      (line    6)
* deleting, foreign key <1>:             innodb-foreign-key-constraints.
                                                             (line  162)
* deleting, foreign key:                 alter-table.        (line  398)
* deleting, function:                    drop-function-udf.  (line    6)
* deleting, index <1>:                   drop-index.         (line    6)
* deleting, index:                       alter-table.        (line  289)
* deleting, primary key:                 alter-table.        (line  304)
* deleting, rows:                        deleting-from-related-tables.
                                                             (line    6)
* deleting, schema:                      drop-database.      (line    6)
* deleting, table:                       drop-table.         (line    6)
* deleting, user <1>:                    drop-user.          (line    6)
* deleting, user:                        removing-users.     (line    6)
* deleting, users <1>:                   drop-user.          (line    6)
* deleting, users:                       removing-users.     (line    6)
* deletion, mysql.sock:                  problems-with-mysql-sock.
                                                             (line    6)
* delimiter command, mysql:              mysql-commands.     (line   81)
* delimiter option, mysql:               mysql-command-options.
                                                             (line  213)
* delimiter option, mysqlslap:           mysqlslap.          (line  298)
* Delphi:                                connector-odbc-usagenotes-apptips-borland-delphi.
                                                             (line    6)
* derived tables:                        unnamed-views.      (line    6)
* des-key-file option, mysqld:           server-options.     (line  466)
* DES_DECRYPT():                         encryption-functions.
                                                             (line  130)
* DES_ENCRYPT():                         encryption-functions.
                                                             (line  151)
* DESC:                                  describe.           (line    6)
* DESCRIBE <1>:                          describe.           (line    6)
* DESCRIBE:                              getting-information.
                                                             (line    6)
* description option, myisamchk:         myisamchk-other-options.
                                                             (line   28)
* design, choices:                       design.             (line    6)
* design, issues:                        bugs.               (line   10)
* design, limitations:                   design-limitations. (line    6)
* detach option, mysqlslap:              mysqlslap.          (line  309)
* development source tree:               installing-source-tree.
                                                             (line    6)
* Difference():                          spatial-operators.  (line   22)
* digits:                                data-types.         (line   36)
* Dimension():                           general-geometry-property-functions.
                                                             (line    9)
* directory structure, default:          installation-layouts.
                                                             (line    6)
* disable named command, mysql:          mysql-command-options.
                                                             (line  218)
* disable-grant-options option, configure: configure-options.
                                                             (line  542)
* disable-keys option, mysqldump:        mysqldump.          (line  396)
* disable-log-bin option, mysqlbinlog:   mysqlbinlog.        (line  208)
* DISCARD TABLESPACE <1>:                multiple-tablespaces.
                                                             (line   59)
* DISCARD TABLESPACE:                    alter-table.        (line  409)
* discard_or_import_tablespace, thread state: general-thread-states.
                                                             (line  104)
* disconnect-slave-event-count option, mysqld: replication-options-slave.
                                                             (line  691)
* disconnecting, from the server:        connecting-disconnecting.
                                                             (line    6)
* Disjoint():                            functions-that-test-spatial-relationships-between-geometries.
                                                             (line   44)
* disk full:                             full-disk.          (line    6)
* disk issues:                           disk-issues.        (line   10)
* disks, splitting data across:          windows-symbolic-links.
                                                             (line    6)
* display size:                          data-types.         (line   31)
* display triggers:                      show-triggers.      (line    6)
* display width:                         data-types.         (line   31)
* displaying, database information:      mysqlshow.          (line    6)
* displaying, information, Cardinality:  show-index.         (line   41)
* displaying, information, Collation:    show-index.         (line   36)
* displaying, information, SHOW <1>:     show-tables.        (line    6)
* displaying, information, SHOW <2>:     show-open-tables.   (line    6)
* displaying, information, SHOW <3>:     show-index.         (line    6)
* displaying, information, SHOW <4>:     show-columns.       (line    6)
* displaying, information, SHOW:         show.               (line   49)
* displaying, table status:              show-table-status.  (line    6)
* Distance():                            functions-that-test-spatial-relationships-between-geometries.
                                                             (line   49)
* DISTINCT <1>:                          select.             (line  446)
* DISTINCT <2>:                          distinct-optimization.
                                                             (line    6)
* DISTINCT:                              selecting-columns.  (line   43)
* DISTINCT, AVG():                       group-by-functions. (line   55)
* DISTINCT, COUNT():                     group-by-functions. (line  119)
* DISTINCT, MAX():                       group-by-functions. (line  179)
* DISTINCT, MIN():                       group-by-functions. (line  199)
* DISTINCT, SUM():                       group-by-functions. (line  250)
* DISTINCTROW:                           select.             (line  446)
* DIV:                                   arithmetic-functions.
                                                             (line  104)
* div_precision_increment system variable: server-system-variables.
                                                             (line 1234)
* division (/):                          arithmetic-functions.
                                                             (line   88)
* DNS:                                   dns.                (line    6)
* DO:                                    do.                 (line    6)
* DocBook XML, documentation source format: manual-info.     (line   30)
* Documentation, in Chinese:             faqs-cjk.           (line   89)
* Documentation, in Japanese:            faqs-cjk.           (line   89)
* Documentation, in Korean:              faqs-cjk.           (line   89)
* Documenters, list of:                  documenters-translators.
                                                             (line    6)
* DOUBLE data type:                      numeric-type-overview.
                                                             (line  192)
* DOUBLE PRECISION data type:            numeric-type-overview.
                                                             (line  209)
* double quote (\"):                     string-syntax.      (line   57)
* downgrading <1>:                       downgrading.        (line   10)
* downgrading:                           upgrade-downgrade.  (line   14)
* downloading:                           getting-mysql.      (line    6)
* DRBD:                                  faqs-drbd.          (line   10)
* DRBD license:                          faqs-drbd.          (line   16)
* drbd, FAQ:                             faqs-mysql-drbd-heartbeat.
                                                             (line   19)
* DROP ... IF EXISTS, and replication:   replication-features-drop-if-exists.
                                                             (line    6)
* DROP DATABASE:                         drop-database.      (line    6)
* Drop DB, thread command:               thread-commands.    (line   46)
* DROP EVENT:                            drop-event.         (line    6)
* DROP FOREIGN KEY <1>:                  innodb-foreign-key-constraints.
                                                             (line  162)
* DROP FOREIGN KEY:                      alter-table.        (line  398)
* DROP FUNCTION <1>:                     drop-function-udf.  (line    6)
* DROP FUNCTION:                         drop-procedure.     (line    6)
* DROP INDEX <1>:                        drop-index.         (line    6)
* DROP INDEX:                            alter-table.        (line  289)
* DROP PREPARE:                          deallocate-prepare. (line    6)
* DROP PRIMARY KEY:                      alter-table.        (line  304)
* DROP PROCEDURE:                        drop-procedure.     (line    6)
* DROP SCHEMA:                           drop-database.      (line    6)
* DROP SERVER:                           drop-server.        (line    6)
* DROP TABLE:                            drop-table.         (line    6)
* DROP TRIGGER:                          drop-trigger.       (line    6)
* DROP USER:                             drop-user.          (line    6)
* DROP VIEW:                             drop-view.          (line    6)
* dropping, user <1>:                    drop-user.          (line    6)
* dropping, user:                        removing-users.     (line    6)
* dryrun option, mysqlhotcopy:           mysqlhotcopy.       (line   98)
* DUAL:                                  select.             (line   64)
* dump option, myisam_ftdump:            myisam-ftdump.      (line   56)
* dump-date option, mysqldump:           mysqldump.          (line  405)
* dump-slave option, mysqldump:          mysqldump.          (line  416)
* DUMPFILE:                              select.             (line  389)
* dumping, databases and tables <1>:     mysqlhotcopy.       (line    6)
* dumping, databases and tables:         mysqldump.          (line    6)
* dynamic table characteristics:         dynamic-format.     (line    6)
* edit command, mysql:                   mysql-commands.     (line  107)
* ego command, mysql:                    mysql-commands.     (line  116)
* Eiffel Wrapper:                        apis-eiffel.        (line    6)
* ELT():                                 string-functions.   (line  230)
* email lists:                           mailing-lists.      (line   10)
* embedded MySQL server library:         libmysqld.          (line   14)
* embedded option, make_win_bin_dist:    make-win-bin-dist.  (line   42)
* embedded option, mysql_config:         mysql-config.       (line   24)
* enable-community-features option, configure: configure-options.
                                                             (line  557)
* enable-debug-sync option, configure:   configure-options.  (line  489)
* enable-dtrace option, configure:       configure-options.  (line  509)
* enable-named-pipe option, mysqld:      server-options.     (line  475)
* enable-profiling option, configure:    configure-options.  (line  563)
* enable-pstack option, mysqld:          server-options.     (line  480)
* enable-thread-safe-client option, configure: configure-options.
                                                             (line  516)
* ENCODE():                              encryption-functions.
                                                             (line  120)
* ENCRYPT():                             encryption-functions.
                                                             (line  202)
* encryption:                            secure-basics.      (line   18)
* encryption functions:                  encryption-functions.
                                                             (line    6)
* END:                                   begin-end.          (line    6)
* end, thread state:                     general-thread-states.
                                                             (line  109)
* EndPoint():                            linestring-property-functions.
                                                             (line   10)
* engine option, mysqlslap:              mysqlslap.          (line  314)
* ENGINES, INFORMATION_SCHEMA table:     engines-table.      (line    6)
* entering, queries:                     entering-queries.   (line    6)
* ENUM data type <1>:                    enum.               (line    6)
* ENUM data type:                        string-type-overview.
                                                             (line  239)
* ENUM, size:                            storage-requirements.
                                                             (line  164)
* Envelope():                            general-geometry-property-functions.
                                                             (line   22)
* environment variable, CC <1>:          environment-variables.
                                                             (line   18)
* environment variable, CC <2>:          compilation-problems.
                                                             (line  108)
* environment variable, CC:              configure-options.  (line  362)
* environment variable, CFLAGS <1>:      environment-variables.
                                                             (line   18)
* environment variable, CFLAGS <2>:      compilation-problems.
                                                             (line  108)
* environment variable, CFLAGS:          configure-options.  (line  376)
* environment variable, CXX <1>:         environment-variables.
                                                             (line   18)
* environment variable, CXX <2>:         compilation-problems.
                                                             (line   66)
* environment variable, CXX:             configure-options.  (line  362)
* environment variable, CXXFLAGS <1>:    environment-variables.
                                                             (line   18)
* environment variable, CXXFLAGS <2>:    compilation-problems.
                                                             (line  108)
* environment variable, CXXFLAGS:        configure-options.  (line  376)
* environment variable, DBI_TRACE <1>:   using-gdb-on-mysqld.
                                                             (line   89)
* environment variable, DBI_TRACE:       environment-variables.
                                                             (line   18)
* environment variable, DBI_USER:        environment-variables.
                                                             (line   18)
* environment variable, HOME <1>:        mysql-command-options.
                                                             (line  562)
* environment variable, HOME:            environment-variables.
                                                             (line   18)
* environment variable, LD_LIBRARY_PATH: perl-support-problems.
                                                             (line   23)
* environment variable, LD_RUN_PATH <1>: perl-support-problems.
                                                             (line   23)
* environment variable, LD_RUN_PATH <2>: environment-variables.
                                                             (line   18)
* environment variable, LD_RUN_PATH <3>: solaris.            (line  149)
* environment variable, LD_RUN_PATH:     source-notes-linux. (line   98)
* environment variable, MYSQL_DEBUG <1>: debugging-client.   (line   10)
* environment variable, MYSQL_DEBUG <2>: programs-overview.  (line  291)
* environment variable, MYSQL_DEBUG:     environment-variables.
                                                             (line   18)
* environment variable, MYSQL_GROUP_SUFFIX: environment-variables.
                                                             (line   18)
* environment variable, MYSQL_HISTFILE <1>: mysql-command-options.
                                                             (line  562)
* environment variable, MYSQL_HISTFILE:  environment-variables.
                                                             (line   18)
* environment variable, MYSQL_HOME:      environment-variables.
                                                             (line   18)
* environment variable, MYSQL_HOST <1>:  connecting.         (line  232)
* environment variable, MYSQL_HOST:      environment-variables.
                                                             (line   18)
* environment variable, MYSQL_PS1:       environment-variables.
                                                             (line   18)
* environment variable, MYSQL_PWD <1>:   connecting.         (line  232)
* environment variable, MYSQL_PWD <2>:   programs-overview.  (line  291)
* environment variable, MYSQL_PWD:       environment-variables.
                                                             (line   18)
* environment variable, MYSQL_TCP_PORT <1>: multiple-server-clients.
                                                             (line   27)
* environment variable, MYSQL_TCP_PORT <2>: multiple-unix-servers.
                                                             (line   59)
* environment variable, MYSQL_TCP_PORT <3>: programs-overview.
                                                             (line  291)
* environment variable, MYSQL_TCP_PORT:  environment-variables.
                                                             (line   18)
* environment variable, MYSQL_UNIX_PORT <1>: multiple-server-clients.
                                                             (line   27)
* environment variable, MYSQL_UNIX_PORT <2>: multiple-unix-servers.
                                                             (line   59)
* environment variable, MYSQL_UNIX_PORT <3>: programs-overview.
                                                             (line  291)
* environment variable, MYSQL_UNIX_PORT <4>: environment-variables.
                                                             (line   18)
* environment variable, MYSQL_UNIX_PORT: mysql-install-db-problems.
                                                             (line   83)
* environment variable, PATH <1>:        invoking-programs.  (line   48)
* environment variable, PATH <2>:        environment-variables.
                                                             (line   18)
* environment variable, PATH:            installing-binary.  (line  115)
* environment variable, TMPDIR <1>:      environment-variables.
                                                             (line   18)
* environment variable, TMPDIR:          mysql-install-db-problems.
                                                             (line   83)
* environment variable, TZ <1>:          timezone-problems.  (line    6)
* environment variable, TZ:              environment-variables.
                                                             (line   18)
* environment variable, UMASK <1>:       file-permissions.   (line    6)
* environment variable, UMASK:           environment-variables.
                                                             (line   18)
* environment variable, UMASK_DIR <1>:   file-permissions.   (line   20)
* environment variable, UMASK_DIR:       environment-variables.
                                                             (line   18)
* environment variable, USER <1>:        connecting.         (line  232)
* environment variable, USER:            environment-variables.
                                                             (line   18)
* environment variables <1>:             access-denied.      (line  108)
* environment variables <2>:             setting-environment-variables.
                                                             (line    6)
* environment variables:                 programs-overview.  (line  288)
* environment variables, CXX:            compilation-problems.
                                                             (line   76)
* environment variables, list of:        environment-variables.
                                                             (line    6)
* eq_ref join type, optimizer:           using-explain.      (line  151)
* equal (=):                             comparison-operators.
                                                             (line   62)
* Equals():                              functions-that-test-spatial-relationships-between-geometries.
                                                             (line   54)
* Errcode:                               perror.             (line    6)
* errno:                                 perror.             (line    6)
* error messages, can't find file:       file-permissions.   (line    6)
* error messages, displaying:            perror.             (line    6)
* error messages, languages:             error-message-language.
                                                             (line    6)
* Error, thread command:                 thread-commands.    (line   50)
* error_count session variable:          server-session-variables.
                                                             (line   93)
* ERROR_FOR_DIVISION_BY_ZERO SQL mode:   server-sql-mode.    (line  113)
* errors, access denied:                 error-access-denied.
                                                             (line    6)
* errors, and replication:               replication-features-slaveerrors.
                                                             (line    6)
* errors, checking tables for:           check.              (line    6)
* errors, common:                        problems.           (line   17)
* errors, directory checksum:            solaris.            (line   11)
* errors, handling for UDFs:             udf-return-values.  (line    6)
* errors, in subqueries:                 subquery-errors.    (line    6)
* errors, known:                         bugs.               (line   10)
* errors, linking:                       link-errors.        (line    6)
* errors, list of:                       common-errors.      (line   28)
* errors, lost connection:               error-lost-connection.
                                                             (line    6)
* errors, reporting <1>:                 bug-reports.        (line    6)
* errors, reporting:                     introduction.       (line   77)
* escape (\\):                           string-syntax.      (line   63)
* escape characters:                     literals.           (line   15)
* estimating, query performance:         estimating-performance.
                                                             (line    6)
* event groups:                          set-global-sql-slave-skip-counter.
                                                             (line    6)
* event restrictions:                    stored-program-restrictions.
                                                             (line    6)
* Event Scheduler:                       events.             (line   15)
* event scheduler:                       stored-programs-views.
                                                             (line   15)
* Event Scheduler, altering events:      alter-event.        (line    6)
* Event Scheduler, and MySQL privileges: events-privileges.  (line    6)
* Event Scheduler, and mysqladmin debug: events-status-info. (line    6)
* Event Scheduler, and replication:      replication-features-invoked.
                                                             (line    6)
* Event Scheduler, and SHOW PROCESSLIST: events-configuration.
                                                             (line   29)
* Event Scheduler, concepts:             events-overview.    (line    6)
* Event Scheduler, creating events:      create-event.       (line    6)
* Event Scheduler, dropping events:      drop-event.         (line    6)
* Event Scheduler, enabling and disabling: events-configuration.
                                                             (line   12)
* Event Scheduler, event metadata:       events-metadata.    (line    6)
* Event Scheduler, obtaining status information: events-status-info.
                                                             (line    6)
* Event Scheduler, SQL statements:       events-syntax.      (line    6)
* Event Scheduler, starting and stopping: events-configuration.
                                                             (line   12)
* event scheduler, thread states:        event-scheduler-thread-states.
                                                             (line    6)
* event-scheduler option, mysqld:        server-options.     (line  521)
* event_scheduler system variable:       server-system-variables.
                                                             (line 1268)
* events <1>:                            events.             (line   15)
* events:                                stored-programs-views.
                                                             (line   15)
* events option, mysqldump:              mysqldump.          (line  436)
* events, altering:                      alter-event.        (line    6)
* events, creating:                      create-event.       (line    6)
* events, dropping:                      drop-event.         (line    6)
* EVENTS, INFORMATION_SCHEMA table <1>:  events-table.       (line    6)
* EVENTS, INFORMATION_SCHEMA table:      events-privileges.  (line   70)
* events, metadata:                      events-metadata.    (line    6)
* events, status variables:              events-privileges.  (line  167)
* exact option, mysqlbackup:             mysqlbackup.        (line  105)
* exact-value literals:                  precision-math.     (line   14)
* example option, mysqld_multi:          mysqld-multi.       (line   85)
* EXAMPLE storage engine <1>:            example-storage-engine.
                                                             (line    6)
* EXAMPLE storage engine:                storage-engines.    (line   24)
* examples, compressed tables:           myisampack.         (line  124)
* examples, myisamchk output:            table-info.         (line   37)
* examples, queries:                     examples.           (line   18)
* exe-suffix option, make_win_bin_dist:  make-win-bin-dist.  (line   47)
* EXECUTE <1>:                           execute.            (line    6)
* EXECUTE:                               sql-syntax-prepared-statements.
                                                             (line   13)
* execute option, mysql:                 mysql-command-options.
                                                             (line  226)
* Execute, thread command:               thread-commands.    (line   52)
* executing SQL statements from text files <1>: batch-commands.
                                                             (line    6)
* executing SQL statements from text files: batch-mode.      (line    6)
* executing, thread state:               general-thread-states.
                                                             (line  116)
* Execution of init_command, thread state: general-thread-states.
                                                             (line  120)
* EXISTS, with subqueries:               exists-and-not-exists-subqueries.
                                                             (line    6)
* exit command, mysql:                   mysql-commands.     (line  121)
* exit-info option, mysqld:              server-options.     (line  541)
* EXP():                                 mathematical-functions.
                                                             (line  195)
* expire_logs_days system variable:      server-system-variables.
                                                             (line 1290)
* EXPLAIN <1>:                           explain.            (line    6)
* EXPLAIN:                               using-explain.      (line    6)
* EXPLAIN PARTITIONS:                    partitioning-info.  (line    6)
* EXPLAIN used with partitioned tables:  partitioning-info.  (line    6)
* explicit default values:               data-type-defaults. (line    6)
* EXPORT_SET():                          string-functions.   (line  241)
* expression aliases <1>:                select.             (line  104)
* expression aliases:                    group-by-hidden-columns.
                                                             (line   52)
* expressions, extended:                 pattern-matching.   (line    6)
* extend-check option, myisamchk <1>:    myisamchk-repair-options.
                                                             (line   27)
* extend-check option, myisamchk:        myisamchk-check-options.
                                                             (line   18)
* extended option, mysqlcheck:           mysqlcheck.         (line  247)
* extended-insert option, mysqldump:     mysqldump.          (line  440)
* extensions, to standard SQL:           compatibility.      (line   15)
* ExteriorRing():                        polygon-property-functions.
                                                             (line   21)
* external locking <1>:                  general-thread-states.
                                                             (line  291)
* external locking <2>:                  external-locking.   (line    6)
* external locking <3>:                  crash-recovery.     (line    6)
* external locking <4>:                  server-system-variables.
                                                             (line 3868)
* external locking:                      server-options.     (line  553)
* external-locking option, mysqld:       server-options.     (line  553)
* extra-file option, my_print_defaults:  my-print-defaults.  (line   43)
* EXTRACT():                             date-and-time-functions.
                                                             (line  516)
* extracting, dates:                     date-calculations.  (line    6)
* ExtractValue():                        xml-functions.      (line  149)
* Falcon storage engine <1>:             se-falcon.          (line   17)
* Falcon storage engine:                 storage-engines.    (line   24)
* FALSE <1>:                             boolean-values.     (line    6)
* FALSE:                                 number-syntax.      (line    6)
* FALSE, testing for:                    comparison-operators.
                                                             (line  128)
* fast option, myisamchk:                myisamchk-check-options.
                                                             (line   30)
* fast option, mysqlcheck:               mysqlcheck.         (line  256)
* fatal signal 11:                       compilation-problems.
                                                             (line   38)
* features of MySQL:                     features.           (line    6)
* FEDERATED storage engine <1>:          federated-storage-engine.
                                                             (line   13)
* FEDERATED storage engine:              storage-engines.    (line   24)
* FETCH:                                 fetch.              (line    6)
* Fetch, thread command:                 thread-commands.    (line   56)
* Field List, thread command:            thread-commands.    (line   61)
* FIELD():                               string-functions.   (line  256)
* field, changing:                       alter-table.        (line  282)
* fields-enclosed-by option, mysqldump <1>: mysqlimport.     (line  156)
* fields-enclosed-by option, mysqldump:  mysqldump.          (line  448)
* fields-escaped-by option, mysqldump <1>: mysqlimport.      (line  160)
* fields-escaped-by option, mysqldump:   mysqldump.          (line  452)
* fields-optionally-enclosed-by option, mysqldump <1>: mysqlimport.
                                                             (line  158)
* fields-optionally-enclosed-by option, mysqldump: mysqldump.
                                                             (line  450)
* fields-terminated-by option, mysqldump <1>: mysqlimport.   (line  154)
* fields-terminated-by option, mysqldump: mysqldump.         (line  446)
* FILE:                                  string-functions.   (line  375)
* files, binary log:                     binary-log.         (line   13)
* files, config.cache:                   compilation-problems.
                                                             (line    6)
* files, error messages:                 error-message-language.
                                                             (line    6)
* files, general query log:              query-log.          (line    6)
* FILES, INFORMATION_SCHEMA table:       files-table.        (line    6)
* files, log <1>:                        log-file-maintenance.
                                                             (line    6)
* files, log:                            configure-options.  (line    6)
* files, my.cnf:                         replication-features.
                                                             (line   38)
* files, not found message:              file-permissions.   (line    6)
* files, permissions:                    file-permissions.   (line    6)
* files, repairing:                      myisamchk-repair-options.
                                                             (line    6)
* files, script:                         batch-mode.         (line    6)
* files, size limits:                    full-table.         (line    6)
* files, slow query log:                 slow-query-log.     (line    6)
* files, text <1>:                       mysqlimport.        (line    6)
* files, text:                           batch-commands.     (line    6)
* files, tmp:                            mysql-install-db-problems.
                                                             (line   70)
* filesort optimization:                 order-by-optimization.
                                                             (line  109)
* FIND_IN_SET():                         string-functions.   (line  275)
* Finished reading one binlog; switching to next binlog, thread state: master-thread-states.
                                                             (line   17)
* first-slave option, mysqldump:         mysqldump.          (line  458)
* fix-db-names option, mysqlcheck:       mysqlcheck.         (line  260)
* fix-table-names option, mysqlcheck:    mysqlcheck.         (line  265)
* FIXED data type:                       numeric-type-overview.
                                                             (line  248)
* fixed-point arithmetic:                precision-math.     (line   14)
* FLOAT data type:                       numeric-type-overview.
                                                             (line  172)
* floating-point number:                 numeric-type-overview.
                                                             (line  217)
* floating-point values, and replication: replication-features-floatvalues.
                                                             (line    6)
* floats:                                number-syntax.      (line    6)
* FLOOR():                               mathematical-functions.
                                                             (line  208)
* FLUSH:                                 flush.              (line    6)
* flush option, mysqld:                  server-options.     (line  575)
* flush system variable:                 server-system-variables.
                                                             (line 1308)
* flush tables:                          mysqladmin.         (line  206)
* FLUSH, and replication:                replication-features-flush.
                                                             (line    6)
* flush-logs option, mysqldump:          mysqldump.          (line  462)
* flush-privileges option, mysqldump:    mysqldump.          (line  474)
* flush_time system variable:            server-system-variables.
                                                             (line 1327)
* Flushing tables, thread state:         general-thread-states.
                                                             (line  130)
* flushlog option, mysqlhotcopy:         mysqlhotcopy.       (line  102)
* FOR UPDATE:                            select.             (line  436)
* FORCE INDEX <1>:                       optimizer-issues.   (line   27)
* FORCE INDEX:                           index-hints.        (line    6)
* FORCE KEY:                             index-hints.        (line    6)
* force option, myisamchk <1>:           myisamchk-repair-options.
                                                             (line   33)
* force option, myisamchk:               myisamchk-check-options.
                                                             (line   34)
* force option, myisampack:              myisampack.         (line   68)
* force option, mysql:                   mysql-command-options.
                                                             (line  232)
* force option, mysql_convert_table_format: mysql-convert-table-format.
                                                             (line   28)
* force option, mysql_install_db:        mysql-install-db.   (line   46)
* force option, mysql_upgrade:           mysql-upgrade.      (line  107)
* force option, mysqladmin:              mysqladmin.         (line  341)
* force option, mysqlcheck:              mysqlcheck.         (line  271)
* force option, mysqldump:               mysqldump.          (line  481)
* force option, mysqlimport:             mysqlimport.        (line  165)
* force-read option, mysqlbinlog:        mysqlbinlog.        (line  222)
* foreign key, constraint:               constraint-primary-key.
                                                             (line    6)
* foreign key, deleting <1>:             innodb-foreign-key-constraints.
                                                             (line  162)
* foreign key, deleting:                 alter-table.        (line  398)
* foreign keys <1>:                      alter-table.        (line  375)
* foreign keys <2>:                      example-foreign-keys.
                                                             (line    6)
* foreign keys:                          ansi-diff-foreign-keys.
                                                             (line    6)
* foreign_key_checks session variable:   server-session-variables.
                                                             (line   99)
* FORMAT():                              string-functions.   (line  290)
* Forums:                                forums.             (line    6)
* FOUND_ROWS():                          information-functions.
                                                             (line  176)
* FreeBSD troubleshooting:               compilation-problems.
                                                             (line  104)
* freeing items, thread state:           general-thread-states.
                                                             (line  125)
* frequently-asked questions about DRBD: faqs-mysql-drbd-heartbeat.
                                                             (line   19)
* frequently-asked questions about MySQL Cluster: faqs-mysql-cluster.
                                                             (line    6)
* FROM:                                  select.             (line  131)
* FROM_DAYS():                           date-and-time-functions.
                                                             (line  532)
* FROM_UNIXTIME():                       date-and-time-functions.
                                                             (line  543)
* ft_boolean_syntax system variable:     server-system-variables.
                                                             (line 1351)
* ft_max_word_len myisamchk variable:    myisamchk-general-options.
                                                             (line   53)
* ft_max_word_len system variable:       server-system-variables.
                                                             (line 1384)
* ft_min_word_len myisamchk variable:    myisamchk-general-options.
                                                             (line   53)
* ft_min_word_len system variable:       server-system-variables.
                                                             (line 1406)
* ft_query_expansion_limit system variable: server-system-variables.
                                                             (line 1428)
* ft_stopword_file myisamchk variable:   myisamchk-general-options.
                                                             (line   53)
* ft_stopword_file system variable:      server-system-variables.
                                                             (line 1446)
* full disk:                             full-disk.          (line    6)
* full-text search:                      fulltext-search.    (line   15)
* FULLTEXT:                              fulltext-search.    (line   15)
* FULLTEXT initialization, thread state: general-thread-states.
                                                             (line  135)
* fulltext join type, optimizer:         using-explain.      (line  195)
* fulltext, stopword list:               fulltext-fine-tuning.
                                                             (line   40)
* function names, parsing:               function-resolution.
                                                             (line    6)
* function names, resolving ambiguity:   function-resolution.
                                                             (line    6)
* function, creating:                    create-function-udf.
                                                             (line    6)
* function, deleting:                    drop-function-udf.  (line    6)
* functions:                             functions.          (line   23)
* functions for SELECT and WHERE clauses: functions.         (line   23)
* functions, and replication:            replication-features-functions.
                                                             (line    6)
* functions, arithmetic:                 bit-functions.      (line    6)
* functions, bit:                        bit-functions.      (line    6)
* functions, C API:                      c-api-function-overview.
                                                             (line    6)
* functions, C prepared statement API:   c-api-prepared-statement-function-overview.
                                                             (line    6)
* functions, cast:                       cast-functions.     (line    6)
* functions, control flow:               control-flow-functions.
                                                             (line    6)
* functions, date and time:              date-and-time-functions.
                                                             (line    6)
* functions, encryption:                 encryption-functions.
                                                             (line    6)
* functions, GROUP BY:                   group-by-functions. (line    6)
* functions, grouping:                   operator-precedence.
                                                             (line   37)
* functions, information:                information-functions.
                                                             (line    6)
* functions, mathematical:               mathematical-functions.
                                                             (line   52)
* functions, miscellaneous:              miscellaneous-functions.
                                                             (line    6)
* functions, native, adding:             adding-native-function.
                                                             (line    6)
* functions, new:                        adding-functions.   (line   12)
* functions, stored:                     stored-routines.    (line   13)
* functions, string:                     string-functions.   (line   11)
* functions, string comparison:          string-comparison-functions.
                                                             (line    6)
* functions, user-defined:               adding-functions.   (line   12)
* Functions, user-defined <1>:           drop-function-udf.  (line    6)
* Functions, user-defined:               create-function-udf.
                                                             (line    6)
* functions, user-defined, adding:       adding-udf.         (line   15)
* gap lock, InnoDB <1>:                  innodb-next-key-locking.
                                                             (line    6)
* gap lock, InnoDB <2>:                  innodb-record-level-locks.
                                                             (line    6)
* gap lock, InnoDB <3>:                  innodb-transaction-model.
                                                             (line   64)
* gap lock, InnoDB:                      innodb-parameters.  (line  367)
* gb2312, gbk:                           faqs-cjk.           (line   13)
* gcc:                                   configure-options.  (line  362)
* gdb option, mysqld:                    server-options.     (line  592)
* gdb, using:                            using-gdb-on-mysqld.
                                                             (line    6)
* general information:                   introduction.       (line   17)
* General Public License:                what-is-mysql.      (line   42)
* general query log:                     query-log.          (line    6)
* general-log option, mysqld:            server-options.     (line  606)
* general_log system variable:           server-system-variables.
                                                             (line 1471)
* general_log_file system variable:      server-system-variables.
                                                             (line 1492)
* geographic feature:                    gis-introduction.   (line   27)
* GeomCollFromText():                    gis-wkt-functions.  (line   14)
* GeomCollFromWKB():                     gis-wkb-functions.  (line   15)
* geometry:                              gis-introduction.   (line   40)
* GEOMETRY data type:                    mysql-spatial-datatypes.
                                                             (line    6)
* GEOMETRYCOLLECTION data type:          mysql-spatial-datatypes.
                                                             (line    6)
* GeometryCollection():                  gis-mysql-specific-functions.
                                                             (line   14)
* GeometryCollectionFromText():          gis-wkt-functions.  (line   14)
* GeometryCollectionFromWKB():           gis-wkb-functions.  (line   15)
* GeometryFromText():                    gis-wkt-functions.  (line   20)
* GeometryFromWKB():                     gis-wkb-functions.  (line   21)
* GeometryN():                           geometrycollection-property-functions.
                                                             (line    8)
* GeometryType():                        general-geometry-property-functions.
                                                             (line   38)
* GeomFromText() <1>:                    functions-to-convert-geometries-between-formats.
                                                             (line   29)
* GeomFromText():                        gis-wkt-functions.  (line   20)
* GeomFromWKB() <1>:                     functions-to-convert-geometries-between-formats.
                                                             (line   36)
* GeomFromWKB():                         gis-wkb-functions.  (line   21)
* geospatial feature:                    gis-introduction.   (line   37)
* GET_FORMAT():                          date-and-time-functions.
                                                             (line  571)
* GET_LOCK():                            miscellaneous-functions.
                                                             (line   40)
* getting MySQL:                         getting-mysql.      (line    6)
* GIS <1>:                               gis-introduction.   (line    6)
* GIS:                                   spatial-extensions. (line   16)
* GLength() <1>:                         multilinestring-property-functions.
                                                             (line    8)
* GLength():                             linestring-property-functions.
                                                             (line   23)
* global privileges <1>:                 revoke.             (line    6)
* global privileges:                     grant.              (line    6)
* GLOBAL_STATUS, INFORMATION_SCHEMA table: status-table.     (line    6)
* GLOBAL_VARIABLES, INFORMATION_SCHEMA table: variables-table.
                                                             (line    6)
* go command, mysql:                     mysql-commands.     (line  125)
* goals of MySQL:                        what-is-mysql.      (line   87)
* got handler lock, thread state:        delayed-insert-thread-states.
                                                             (line   26)
* got old table, thread state:           delayed-insert-thread-states.
                                                             (line   32)
* GRANT:                                 grant.              (line    6)
* GRANT statement:                       adding-users.       (line    6)
* grant tables, re-creating:             mysql-install-db-problems.
                                                             (line  103)
* grant tables, sorting <1>:             request-access.     (line   52)
* grant tables, sorting:                 connection-access.  (line  120)
* grant tables, structure:               grant-table-structure.
                                                             (line    6)
* grant tables, upgrading:               mysql-fix-privilege-tables.
                                                             (line    6)
* granting, privileges:                  grant.              (line    6)
* GRANTS:                                show-grants.        (line    6)
* greater than (>):                      comparison-operators.
                                                             (line  121)
* greater than or equal (>=):            comparison-operators.
                                                             (line  114)
* GREATEST():                            comparison-operators.
                                                             (line  220)
* GROUP BY:                              group-by-optimization.
                                                             (line   11)
* GROUP BY functions:                    group-by-functions. (line    6)
* GROUP BY, aliases in:                  group-by-hidden-columns.
                                                             (line   52)
* GROUP BY, extensions to standard SQL <1>: select.          (line  201)
* GROUP BY, extensions to standard SQL:  group-by-hidden-columns.
                                                             (line    6)
* GROUP_CONCAT():                        group-by-functions. (line  132)
* group_concat_max_len system variable:  server-system-variables.
                                                             (line 1510)
* grouping, expressions:                 operator-precedence.
                                                             (line   37)
* HANDLER:                               handler.            (line    6)
* Handlers:                              declare-handler.    (line    6)
* handling, errors:                      udf-return-values.  (line    6)
* Has read all relay log; waiting for the slave I/O thread to update it, thread state: slave-sql-thread-states.
                                                             (line   18)
* Has sent all binlog to slave; waiting for binlog to be updated, thread state: master-thread-states.
                                                             (line   22)
* hash partitioning:                     partitioning-hash.  (line   10)
* hash partitions, managing:             partitioning-management-hash-key.
                                                             (line    6)
* hash partitions, splitting and merging: partitioning-management-hash-key.
                                                             (line    6)
* have_compress system variable:         server-system-variables.
                                                             (line 1534)
* have_crypt system variable:            server-system-variables.
                                                             (line 1540)
* have_csv system variable:              server-system-variables.
                                                             (line 1545)
* have_dynamic_loading system variable:  server-system-variables.
                                                             (line 1550)
* have_geometry system variable:         server-system-variables.
                                                             (line 1555)
* have_innodb system variable:           server-system-variables.
                                                             (line 1559)
* have_openssl system variable:          server-system-variables.
                                                             (line 1564)
* have_partitioning system variable:     server-system-variables.
                                                             (line 1568)
* have_query_cache system variable:      server-system-variables.
                                                             (line 1572)
* have_rtree_keys system variable:       server-system-variables.
                                                             (line 1577)
* have_ssl system variable:              server-system-variables.
                                                             (line 1582)
* have_symlink system variable:          server-system-variables.
                                                             (line 1587)
* HAVING:                                select.             (line  215)
* header_file option, comp_err:          comp-err.           (line   44)
* HEAP storage engine <1>:               memory-storage-engine.
                                                             (line    6)
* HEAP storage engine:                   storage-engines.    (line   24)
* help command, mysql:                   mysql-commands.     (line   51)
* help option, comp_err:                 comp-err.           (line   26)
* help option, my_print_defaults:        my-print-defaults.  (line   25)
* help option, myisam_ftdump:            myisam-ftdump.      (line   48)
* HELP option, myisamchk:                myisamchk-general-options.
                                                             (line   16)
* help option, myisamchk:                myisamchk-general-options.
                                                             (line   11)
* help option, myisampack:               myisampack.         (line   49)
* help option, mysql:                    mysql-command-options.
                                                             (line  130)
* help option, mysql_convert_table_format: mysql-convert-table-format.
                                                             (line   24)
* help option, mysql_find_rows:          mysql-find-rows.    (line   31)
* help option, mysql_setpermission:      mysql-setpermission.
                                                             (line   29)
* help option, mysql_upgrade:            mysql-upgrade.      (line   86)
* help option, mysql_waitpid:            mysql-waitpid.      (line   27)
* help option, mysqlaccess:              mysqlaccess.        (line   60)
* help option, mysqladmin:               mysqladmin.         (line  302)
* help option, mysqlbackup:              mysqlbackup.        (line   73)
* help option, mysqlbinlog:              mysqlbinlog.        (line  124)
* help option, mysqlcheck:               mysqlcheck.         (line  163)
* help option, mysqld:                   server-options.     (line   51)
* help option, mysqld_multi:             mysqld-multi.       (line   76)
* help option, mysqld_safe:              mysqld-safe.        (line   99)
* help option, mysqldump:                mysqldump.          (line  258)
* help option, mysqldumpslow:            mysqldumpslow.      (line   44)
* help option, mysqlhotcopy:             mysqlhotcopy.       (line   69)
* help option, mysqlimport:              mysqlimport.        (line  111)
* help option, mysqlshow:                mysqlshow.          (line  101)
* help option, mysqlslap:                mysqlslap.          (line  192)
* help option, perror:                   perror.             (line   35)
* help option, resolve_stack_dump:       resolve-stack-dump. (line   21)
* help option, resolveip:                resolveip.          (line   16)
* HELP statement:                        help.               (line    6)
* HEX() <1>:                             mathematical-functions.
                                                             (line  227)
* HEX():                                 string-functions.   (line  303)
* hex-blob option, mysqldump:            mysqldump.          (line  499)
* hexadecimal values:                    hexadecimal-values. (line    6)
* hexdump option, mysqlbinlog:           mysqlbinlog.        (line  229)
* HIGH_NOT_PRECEDENCE SQL mode:          server-sql-mode.    (line  122)
* HIGH_PRIORITY:                         select.             (line  455)
* hints:                                 extensions-to-ansi. (line    6)
* hints, index <1>:                      index-hints.        (line    6)
* hints, index:                          select.             (line  139)
* history of MySQL:                      history.            (line    6)
* HOME environment variable <1>:         mysql-command-options.
                                                             (line  562)
* HOME environment variable:             environment-variables.
                                                             (line   18)
* host name caching:                     dns.                (line    6)
* host name resolution:                  dns.                (line    6)
* host name, default:                    connecting.         (line    6)
* host option:                           connecting.         (line  129)
* host option, mysql:                    mysql-command-options.
                                                             (line  236)
* host option, mysql_convert_table_format: mysql-convert-table-format.
                                                             (line   32)
* host option, mysql_setpermission:      mysql-setpermission.
                                                             (line   33)
* host option, mysqlaccess:              mysqlaccess.        (line   87)
* host option, mysqladmin:               mysqladmin.         (line  346)
* host option, mysqlbinlog:              mysqlbinlog.        (line  235)
* host option, mysqlcheck:               mysqlcheck.         (line  275)
* host option, mysqldump:                mysqldump.          (line  494)
* host option, mysqlhotcopy:             mysqlhotcopy.       (line  106)
* host option, mysqlimport:              mysqlimport.        (line  171)
* host option, mysqlshow:                mysqlshow.          (line  139)
* host option, mysqlslap:                mysqlslap.          (line  318)
* host table:                            request-access.     (line  150)
* host table, sorting:                   request-access.     (line   52)
* host.frm, problems finding:            unix-post-installation.
                                                             (line  137)
* hostname system variable:              server-system-variables.
                                                             (line 1594)
* HOUR():                                date-and-time-functions.
                                                             (line  608)
* howto option, mysqlaccess:             mysqlaccess.        (line   91)
* html option, mysql:                    mysql-command-options.
                                                             (line  240)
* i-am-a-dummy option, mysql:            mysql-command-options.
                                                             (line  393)
* ID, unique:                            getting-unique-id.  (line    6)
* identifiers:                           identifiers.        (line   13)
* identifiers, case sensitivity:         identifier-case-sensitivity.
                                                             (line    6)
* identifiers, quoting:                  identifiers.        (line   20)
* identity session variable:             server-session-variables.
                                                             (line  120)
* IF:                                    if-statement.       (line    6)
* IF():                                  control-flow-functions.
                                                             (line   47)
* IFNULL():                              control-flow-functions.
                                                             (line   84)
* IGNORE INDEX:                          index-hints.        (line    6)
* IGNORE KEY:                            index-hints.        (line    6)
* ignore option, mysqlimport:            mysqlimport.        (line  176)
* IGNORE, with partitioned tables:       insert.             (line  261)
* ignore-lines option, mysqlimport:      mysqlimport.        (line  180)
* ignore-spaces option, mysql:           mysql-command-options.
                                                             (line  244)
* ignore-sql-errors option, mysqlslap:   mysqlslap.          (line  322)
* ignore-table option, mysqldump:        mysqldump.          (line  514)
* IGNORE_SPACE SQL mode:                 server-sql-mode.    (line  137)
* image-order option, mysqlbackup:       mysqlbackup.        (line  110)
* implicit default values:               data-type-defaults. (line    6)
* IMPORT TABLESPACE <1>:                 multiple-tablespaces.
                                                             (line   59)
* IMPORT TABLESPACE:                     alter-table.        (line  409)
* importing, data <1>:                   mysqlimport.        (line    6)
* importing, data:                       batch-commands.     (line    6)
* IN <1>:                                any-in-some-subqueries.
                                                             (line    6)
* IN:                                    comparison-operators.
                                                             (line  235)
* in_file option, comp_err:              comp-err.           (line   48)
* include option, mysql_config:          mysql-config.       (line   20)
* include-master-host-port option, mysqldump: mysqldump.     (line  506)
* increasing with replication, speed:    replication.        (line   13)
* increasing, performance:               replication-faq.    (line   31)
* INDEX DIRECTORY, and replication:      replication-features-directory.
                                                             (line    6)
* index hints <1>:                       index-hints.        (line    6)
* index hints:                           select.             (line  139)
* index join type, optimizer:            using-explain.      (line  262)
* index, deleting <1>:                   drop-index.         (line    6)
* index, deleting:                       alter-table.        (line  289)
* index, rebuilding:                     rebuilding-tables.  (line    6)
* index-record lock, InnoDB <1>:         innodb-next-key-locking.
                                                             (line    6)
* index-record lock, InnoDB <2>:         innodb-record-level-locks.
                                                             (line    6)
* index-record lock, InnoDB <3>:         innodb-transaction-model.
                                                             (line   64)
* index-record lock, InnoDB:             innodb-parameters.  (line  367)
* index_merge join type, optimizer:      using-explain.      (line  212)
* index_subquery join type, optimizer:   using-explain.      (line  230)
* indexes:                               create-index.       (line    6)
* indexes, and BLOB columns <1>:         create-table.       (line  404)
* indexes, and BLOB columns:             indexes.            (line   15)
* indexes, and IS NULL:                  mysql-indexes.      (line  135)
* indexes, and LIKE:                     mysql-indexes.      (line  109)
* indexes, and NULL values:              create-table.       (line  383)
* indexes, and TEXT columns <1>:         create-table.       (line  404)
* indexes, and TEXT columns:             indexes.            (line   15)
* indexes, assigning to key cache:       cache-index.        (line    6)
* indexes, block size:                   server-system-variables.
                                                             (line 1818)
* indexes, columns:                      indexes.            (line    6)
* indexes, leftmost prefix of:           mysql-indexes.      (line   88)
* indexes, multi-column:                 multiple-column-indexes.
                                                             (line    6)
* indexes, multiple-part:                create-index.       (line    6)
* indexes, names:                        identifiers.        (line   13)
* indexes, use of:                       mysql-indexes.      (line    6)
* INET_ATON():                           miscellaneous-functions.
                                                             (line   96)
* INET_NTOA():                           miscellaneous-functions.
                                                             (line  122)
* information functions:                 information-functions.
                                                             (line    6)
* information option, myisamchk:         myisamchk-check-options.
                                                             (line   40)
* INFORMATION_SCHEMA:                    information-schema. (line   39)
* Init DB, thread command:               thread-commands.    (line   65)
* init, thread state:                    general-thread-states.
                                                             (line  140)
* init-file option, mysqld:              server-options.     (line  625)
* init_connect system variable:          server-system-variables.
                                                             (line 1604)
* init_file system variable:             server-system-variables.
                                                             (line 1642)
* init_slave system variable:            replication-options-slave.
                                                             (line  741)
* Initialized, thread state:             event-scheduler-thread-states.
                                                             (line   15)
* INNER JOIN:                            join.               (line    6)
* innochecksum <1>:                      innochecksum.       (line    6)
* innochecksum:                          programs-overview.  (line  152)
* InnoDB:                                innodb.             (line   23)
* innodb option, mysqld:                 innodb-parameters.  (line  117)
* InnoDB storage engine <1>:             innodb.             (line   23)
* InnoDB storage engine:                 storage-engines.    (line   24)
* InnoDB tables:                         ansi-diff-transactions.
                                                             (line    6)
* InnoDB, clustered index:               innodb-index-types. (line    6)
* InnoDB, gap lock <1>:                  innodb-next-key-locking.
                                                             (line    6)
* InnoDB, gap lock <2>:                  innodb-record-level-locks.
                                                             (line    6)
* InnoDB, gap lock <3>:                  innodb-transaction-model.
                                                             (line   64)
* InnoDB, gap lock:                      innodb-parameters.  (line  367)
* InnoDB, index-record lock <1>:         innodb-next-key-locking.
                                                             (line    6)
* InnoDB, index-record lock <2>:         innodb-record-level-locks.
                                                             (line    6)
* InnoDB, index-record lock <3>:         innodb-transaction-model.
                                                             (line   64)
* InnoDB, index-record lock:             innodb-parameters.  (line  367)
* InnoDB, Monitors <1>:                  innodb-troubleshooting-datadict.
                                                             (line   57)
* InnoDB, Monitors <2>:                  innodb-troubleshooting.
                                                             (line   20)
* InnoDB, Monitors <3>:                  innodb-monitors.    (line   12)
* InnoDB, Monitors <4>:                  innodb-file-space.  (line   66)
* InnoDB, Monitors:                      innodb-backup.      (line  102)
* InnoDB, next-key lock <1>:             innodb-next-key-locking.
                                                             (line    6)
* InnoDB, next-key lock <2>:             innodb-record-level-locks.
                                                             (line    6)
* InnoDB, next-key lock <3>:             innodb-transaction-model.
                                                             (line   64)
* InnoDB, next-key lock:                 innodb-parameters.  (line  367)
* InnoDB, NFS <1>:                       innodb-restrictions.
                                                             (line   16)
* InnoDB, NFS:                           innodb-configuration.
                                                             (line   47)
* InnoDB, record-level locks <1>:        innodb-next-key-locking.
                                                             (line    6)
* InnoDB, record-level locks <2>:        innodb-record-level-locks.
                                                             (line    6)
* InnoDB, record-level locks <3>:        innodb-transaction-model.
                                                             (line   64)
* InnoDB, record-level locks:            innodb-parameters.  (line  367)
* InnoDB, secondary index:               innodb-index-types. (line    6)
* InnoDB, semi-consistent read:          innodb-parameters.  (line  367)
* InnoDB, Solaris 10 x86_64 issues:      solaris.            (line   11)
* InnoDB, transaction isolation levels:  innodb-transaction-model.
                                                             (line   52)
* innodb_status_file option, mysqld:     innodb-parameters.  (line  122)
* INSERT <1>:                            insert.             (line   12)
* INSERT:                                insert-speed.       (line    6)
* INSERT ... SELECT:                     insert-select.      (line    6)
* INSERT DELAYED:                        insert-delayed.     (line    6)
* INSERT statement, grant privileges:    adding-users.       (line  116)
* INSERT():                              string-functions.   (line  321)
* insert, thread state:                  delayed-insert-thread-states.
                                                             (line   74)
* insert-ignore option, mysqldump:       mysqldump.          (line  521)
* insert_id session variable:            server-session-variables.
                                                             (line  127)
* insertable views, insertable:          view-updatability.  (line    6)
* inserting, speed of:                   insert-speed.       (line    6)
* inserts, concurrent <1>:               concurrent-inserts. (line    6)
* inserts, concurrent:                   internal-locking.   (line   71)
* INSTALL PLUGIN:                        install-plugin.     (line    6)
* installation layouts:                  installation-layouts.
                                                             (line    6)
* installation overview:                 installing-source.  (line   16)
* installing plugins:                    install-plugin.     (line    6)
* installing, binary distribution:       installing-binary.  (line    6)
* installing, Linux RPM packages:        linux-rpm.          (line    6)
* installing, Mac OS X PKG packages:     mac-os-x-installation.
                                                             (line    6)
* installing, overview:                  installing.         (line   23)
* installing, Perl:                      perl-support.       (line   12)
* installing, Perl on Windows:           activestate-perl.   (line    6)
* installing, Solaris PKG packages:      solaris-installation.
                                                             (line    6)
* installing, source distribution:       installing-source.  (line   16)
* installing, user-defined functions:    udf-compiling.      (line    6)
* INSTR():                               string-functions.   (line  339)
* INT data type:                         numeric-type-overview.
                                                             (line  118)
* integer arithmetic:                    precision-math.     (line   14)
* INTEGER data type:                     numeric-type-overview.
                                                             (line  123)
* integers:                              number-syntax.      (line    6)
* interactive_timeout system variable:   server-system-variables.
                                                             (line 1669)
* InteriorRingN():                       polygon-property-functions.
                                                             (line   35)
* internal compiler errors:              compilation-problems.
                                                             (line   38)
* internal locking:                      internal-locking.   (line    6)
* internals:                             mysql-internals.    (line   11)
* internationalization:                  internationalization-localization.
                                                             (line   17)
* Internet Relay Chat:                   irc.                (line    6)
* Intersection():                        spatial-operators.  (line   27)
* Intersects():                          functions-that-test-spatial-relationships-between-geometries.
                                                             (line   58)
* INTERVAL():                            comparison-operators.
                                                             (line  295)
* introducer, string literal <1>:        charset-literal.    (line   11)
* introducer, string literal:            string-syntax.      (line   33)
* invalid data, constraint:              constraint-invalid-data.
                                                             (line    6)
* IRC:                                   irc.                (line    6)
* IS boolean_value:                      comparison-operators.
                                                             (line  128)
* IS NOT boolean_value:                  comparison-operators.
                                                             (line  136)
* IS NOT NULL:                           comparison-operators.
                                                             (line  172)
* IS NULL <1>:                           comparison-operators.
                                                             (line  144)
* IS NULL:                               is-null-optimization.
                                                             (line    6)
* IS NULL, and indexes:                  mysql-indexes.      (line  135)
* IS_FREE_LOCK():                        miscellaneous-functions.
                                                             (line  131)
* IS_USED_LOCK():                        miscellaneous-functions.
                                                             (line  138)
* isamlog <1>:                           myisamlog.          (line    6)
* isamlog:                               programs-overview.  (line  167)
* IsClosed():                            multilinestring-property-functions.
                                                             (line   25)
* IsEmpty():                             general-geometry-property-functions.
                                                             (line   75)
* ISNULL():                              comparison-operators.
                                                             (line  278)
* ISOLATION LEVEL:                       set-transaction.    (line    6)
* IsRing():                              linestring-property-functions.
                                                             (line   80)
* IsSimple():                            general-geometry-property-functions.
                                                             (line   81)
* ITERATE:                               iterate-statement.  (line    6)
* iterations option, mysqlslap:          mysqlslap.          (line  328)
* Japanese character sets, conversion:   faqs-cjk.           (line   25)
* Japanese, Korean, Chinese character sets, frequently asked questions: faqs-cjk.
                                                             (line    6)
* JOIN:                                  join.               (line    6)
* join algorithm, Block Nested-Loop:     nested-loop-joins.  (line    6)
* join algorithm, Nested-Loop:           nested-loop-joins.  (line    6)
* join option, myisampack:               myisampack.         (line   80)
* join type, ALL:                        using-explain.      (line  271)
* join type, const:                      using-explain.      (line  134)
* join type, eq_ref:                     using-explain.      (line  151)
* join type, fulltext:                   using-explain.      (line  195)
* join type, index:                      using-explain.      (line  262)
* join type, index_merge:                using-explain.      (line  212)
* join type, index_subquery:             using-explain.      (line  230)
* join type, range:                      using-explain.      (line  238)
* join type, ref:                        using-explain.      (line  172)
* join type, ref_or_null:                using-explain.      (line  199)
* join type, system:                     using-explain.      (line  129)
* join type, unique_subquery:            using-explain.      (line  220)
* join, nested-loop algorithm:           nested-join-optimization.
                                                             (line  167)
* join_buffer_size system variable:      server-system-variables.
                                                             (line 1690)
* join_cache_level system variable:      server-system-variables.
                                                             (line 1727)
* keep_files_on_create system variable:  server-system-variables.
                                                             (line 1790)
* keepold option, mysqlhotcopy:          mysqlhotcopy.       (line  112)
* key cache, assigning indexes to:       cache-index.        (line    6)
* Key cache, MyISAM:                     myisam-key-cache.   (line   15)
* key partitioning:                      partitioning-key.   (line    6)
* key partitions, managing:              partitioning-management-hash-key.
                                                             (line    6)
* key partitions, splitting and merging: partitioning-management-hash-key.
                                                             (line    6)
* key space, MyISAM:                     key-space.          (line    6)
* key_buffer_size myisamchk variable:    myisamchk-general-options.
                                                             (line   53)
* key_buffer_size system variable:       server-system-variables.
                                                             (line 1818)
* key_cache_age_threshold system variable: server-system-variables.
                                                             (line 1883)
* key_cache_block_size system variable:  server-system-variables.
                                                             (line 1909)
* key_cache_division_limit system variable: server-system-variables.
                                                             (line 1927)
* KEY_COLUMN_USAGE, INFORMATION_SCHEMA table: key-column-usage-table.
                                                             (line    6)
* keys:                                  indexes.            (line    6)
* keys option, mysqlshow:                mysqlshow.          (line  143)
* keys, foreign <1>:                     example-foreign-keys.
                                                             (line    6)
* keys, foreign:                         ansi-diff-foreign-keys.
                                                             (line    6)
* keys, multi-column:                    multiple-column-indexes.
                                                             (line    6)
* keys, searching on two:                searching-on-two-keys.
                                                             (line    6)
* keys-used option, myisamchk:           myisamchk-repair-options.
                                                             (line   38)
* keywords:                              reserved-words.     (line    6)
* KILL:                                  kill.               (line    6)
* Kill, thread command:                  thread-commands.    (line   69)
* Killed, thread state:                  general-thread-states.
                                                             (line  146)
* Killing slave, thread state:           slave-connection-thread-states.
                                                             (line   14)
* known errors:                          bugs.               (line   10)
* Korean:                                faqs-cjk.           (line   39)
* Korean, Chinese, Japanese character sets, frequently asked questions: faqs-cjk.
                                                             (line    6)
* label option, mysqlslap:               mysqlslap.          (line  332)
* language option, mysqld:               server-options.     (line  648)
* language support, error messages:      error-message-language.
                                                             (line    6)
* language system variable:              server-system-variables.
                                                             (line 1947)
* large page support:                    large-page-support. (line    6)
* large-pages option, mysqld:            server-options.     (line  667)
* large_files_support system variable:   server-system-variables.
                                                             (line 1963)
* large_page_size system variable:       server-system-variables.
                                                             (line 1990)
* large_pages system variable:           server-system-variables.
                                                             (line 1972)
* last row, unique ID:                   getting-unique-id.  (line    6)
* LAST_DAY():                            date-and-time-functions.
                                                             (line  620)
* last_insert_id session variable:       server-session-variables.
                                                             (line  133)
* LAST_INSERT_ID() <1>:                  insert.             (line  206)
* LAST_INSERT_ID():                      ansi-diff-transactions.
                                                             (line  165)
* LAST_INSERT_ID() and stored routines:  stored-routines-last-insert-id.
                                                             (line    6)
* LAST_INSERT_ID() and triggers:         stored-routines-last-insert-id.
                                                             (line    6)
* LAST_INSERT_ID(), and replication:     replication-features-auto-increment.
                                                             (line    6)
* LAST_INSERT_ID([<replaceable>expr</replaceable>]): information-functions.
                                                             (line  259)
* layout of installation:                installation-layouts.
                                                             (line    6)
* lc_time_names system variable:         server-system-variables.
                                                             (line 2004)
* LCASE():                               string-functions.   (line  353)
* LD_LIBRARY_PATH environment variable:  perl-support-problems.
                                                             (line   23)
* LD_RUN_PATH environment variable <1>:  perl-support-problems.
                                                             (line   23)
* LD_RUN_PATH environment variable <2>:  environment-variables.
                                                             (line   18)
* LD_RUN_PATH environment variable <3>:  solaris.            (line  149)
* LD_RUN_PATH environment variable:      source-notes-linux. (line   98)
* ldata option, mysql_install_db:        mysql-install-db.   (line   52)
* LEAST():                               comparison-operators.
                                                             (line  309)
* LEAVE:                                 leave-statement.    (line    6)
* ledir option, mysqld_safe:             mysqld-safe.        (line  141)
* LEFT JOIN <1>:                         join.               (line    6)
* LEFT JOIN:                             left-join-optimization.
                                                             (line    6)
* LEFT OUTER JOIN:                       join.               (line    6)
* LEFT():                                string-functions.   (line  357)
* leftmost prefix of indexes:            mysql-indexes.      (line   88)
* legal names:                           identifiers.        (line   13)
* length option, myisam_ftdump:          myisam-ftdump.      (line   60)
* LENGTH():                              string-functions.   (line  365)
* less than (<):                         comparison-operators.
                                                             (line  107)
* less than or equal (<=):               comparison-operators.
                                                             (line  100)
* libmysqld:                             libmysqld.          (line   14)
* libmysqld, options:                    libmysqld-options.  (line    6)
* libmysqld-libs option, mysql_config:   mysql-config.       (line   24)
* libraries, list of:                    used-libraries.     (line    6)
* library, mysqlclient:                  connectors-apis.    (line   26)
* library, mysqld:                       connectors-apis.    (line   26)
* libs option, mysql_config:             mysql-config.       (line   29)
* libs_r option, mysql_config:           mysql-config.       (line   34)
* license system variable:               server-system-variables.
                                                             (line 2020)
* LIKE:                                  string-comparison-functions.
                                                             (line   18)
* LIKE, and indexes:                     mysql-indexes.      (line  109)
* LIKE, and wildcards:                   mysql-indexes.      (line  109)
* LIMIT <1>:                             select.             (line  272)
* LIMIT <2>:                             information-functions.
                                                             (line  176)
* LIMIT:                                 limit-optimization. (line    6)
* LIMIT, and replication:                replication-features-limit.
                                                             (line    6)
* limitations, design:                   design-limitations. (line    6)
* limitations, MySQL Limitations:        limits.             (line   12)
* limitations, replication:              replication-features.
                                                             (line   38)
* limits, file-size:                     full-table.         (line    6)
* limits, MySQL Limits, limits in MySQL: limits.             (line   12)
* line-numbers option, mysql:            mysql-command-options.
                                                             (line  250)
* linear hash partitioning:              partitioning-linear-hash.
                                                             (line    6)
* linear key partitioning:               partitioning-key.   (line   83)
* linefeed (\n) <1>:                     load-data.          (line  426)
* linefeed (\n):                         string-syntax.      (line   59)
* LineFromText():                        gis-wkt-functions.  (line   25)
* LineFromWKB():                         gis-wkb-functions.  (line   26)
* lines-terminated-by option, mysqldump <1>: mysqlimport.    (line  184)
* lines-terminated-by option, mysqldump: mysqldump.          (line  525)
* LINESTRING data type:                  mysql-spatial-datatypes.
                                                             (line    6)
* LineString():                          gis-mysql-specific-functions.
                                                             (line   20)
* LineStringFromText():                  gis-wkt-functions.  (line   25)
* LineStringFromWKB():                   gis-wkb-functions.  (line   26)
* linking:                               building-clients.   (line    6)
* linking, errors:                       link-errors.        (line    6)
* linking, problems:                     c-api-linking-problems.
                                                             (line    6)
* linking, speed:                        compile-and-link-options.
                                                             (line    6)
* links, symbolic:                       symbolic-links.     (line   12)
* Linux, binary distribution:            binary-notes-linux. (line    6)
* Linux, source distribution:            source-notes-linux. (line    6)
* list partitioning:                     partitioning-list.  (line    6)
* list partitions, adding and dropping:  partitioning-management-range-list.
                                                             (line    6)
* list partitions, managing:             partitioning-management-range-list.
                                                             (line    6)
* literals:                              literals.           (line   15)
* LN():                                  mathematical-functions.
                                                             (line  234)
* LOAD DATA INFILE <1>:                  problems-with-null. (line   51)
* LOAD DATA INFILE:                      load-data.          (line    6)
* LOAD DATA, and replication:            replication-features-load-data.
                                                             (line    6)
* load emulation:                        mysqlslap.          (line    6)
* LOAD INDEX INTO CACHE, and partitioning: partitioning-limitations.
                                                             (line  293)
* LOAD XML:                              load-xml.           (line    6)
* LOAD_FILE():                           string-functions.   (line  375)
* loading, tables:                       loading-tables.     (line    6)
* local option, mysqlimport:             mysqlimport.        (line  193)
* local-infile option, mysql:            mysql-command-options.
                                                             (line  255)
* local-infile option, mysqld:           privileges-options. (line   46)
* local-load option, mysqlbinlog:        mysqlbinlog.        (line  239)
* local_infile system variable:          server-system-variables.
                                                             (line 2031)
* localization:                          internationalization-localization.
                                                             (line   17)
* localstatedir option, configure:       configure-options.  (line  321)
* LOCALTIME:                             date-and-time-functions.
                                                             (line  635)
* LOCALTIMESTAMP:                        date-and-time-functions.
                                                             (line  639)
* LOCATE():                              string-functions.   (line  395)
* LOCK IN SHARE MODE:                    select.             (line  436)
* Lock Monitor, InnoDB:                  innodb-monitors.    (line   12)
* LOCK TABLES:                           lock-tables.        (line   12)
* lock-all-tables option, mysqldump:     mysqldump.          (line  531)
* lock-tables option, mysqldump:         mysqldump.          (line  538)
* lock-tables option, mysqlimport:       mysqlimport.        (line  204)
* Locked, thread state:                  general-thread-states.
                                                             (line  155)
* locked_in_memory system variable:      server-system-variables.
                                                             (line 2042)
* locking:                               system-optimization.
                                                             (line   24)
* locking methods:                       internal-locking.   (line    6)
* locking, external <1>:                 general-thread-states.
                                                             (line  291)
* locking, external <2>:                 external-locking.   (line    6)
* locking, external <3>:                 crash-recovery.     (line    6)
* locking, external <4>:                 server-system-variables.
                                                             (line 3868)
* locking, external:                     server-options.     (line  553)
* locking, internal:                     internal-locking.   (line    6)
* locking, row-level <1>:                internal-locking.   (line    6)
* locking, row-level:                    ansi-diff-transactions.
                                                             (line  173)
* locking, table-level:                  internal-locking.   (line    6)
* log files:                             configure-options.  (line    6)
* log files, maintaining:                log-file-maintenance.
                                                             (line    6)
* log option, mysqld:                    server-options.     (line  695)
* log option, mysqld_multi:              mysqld-multi.       (line   89)
* log system variable:                   server-system-variables.
                                                             (line 2051)
* LOG():                                 mathematical-functions.
                                                             (line  248)
* log, changes:                          news.               (line   19)
* log-backup-output option, mysqld:      server-options.     (line  722)
* log-bin option, mysqld:                replication-options-binary-log.
                                                             (line   44)
* log-bin-index option, mysqld:          replication-options-binary-log.
                                                             (line   68)
* log-bin-trust-function-creators option, mysqld: replication-options-binary-log.
                                                             (line  246)
* log-error option, mysqld:              server-options.     (line  761)
* log-error option, mysqld_safe:         mysqld-safe.        (line  147)
* log-error option, mysqldump:           mysqldump.          (line  552)
* log-isam option, mysqld:               server-options.     (line  779)
* log-long-format option, mysqld:        server-options.     (line  790)
* log-output option, mysqld:             server-options.     (line  805)
* log-queries-not-using-indexes option, mysqld: server-options.
                                                             (line  841)
* log-short-format option, mysqld:       server-options.     (line  862)
* log-slave-updates option, mysqld:      replication-options-slave.
                                                             (line   90)
* log-slow-admin-statements option, mysqld: server-options.  (line  875)
* log-slow-queries option, mysqld:       server-options.     (line  888)
* log-slow-slave-statements option, mysqld: replication-options-slave.
                                                             (line  110)
* log-tc option, mysqld:                 server-options.     (line  918)
* log-tc-size option, mysqld:            server-options.     (line  933)
* log-warnings option, mysqld <1>:       replication-options-slave.
                                                             (line  126)
* log-warnings option, mysqld:           server-options.     (line  952)
* LOG10():                               mathematical-functions.
                                                             (line  288)
* LOG2():                                mathematical-functions.
                                                             (line  275)
* log_bin system variable:               server-system-variables.
                                                             (line 2059)
* log_bin_trust_function_creators system variable: server-system-variables.
                                                             (line 2067)
* log_error system variable:             server-system-variables.
                                                             (line 2094)
* log_output system variable:            server-system-variables.
                                                             (line 2109)
* log_queries_not_using_indexes system variable: server-system-variables.
                                                             (line 2135)
* log_slave_updates system variable:     server-system-variables.
                                                             (line 2152)
* log_slow_queries system variable:      server-system-variables.
                                                             (line 2159)
* log_warnings system variable:          server-system-variables.
                                                             (line 2179)
* logging slow query, thread state:      general-thread-states.
                                                             (line  159)
* logical operators:                     logical-operators.  (line    6)
* login, thread state:                   general-thread-states.
                                                             (line  168)
* logs, server:                          server-logs.        (line   15)
* LONG data type:                        blob.               (line    6)
* Long Data, thread command:             thread-commands.    (line   73)
* long_query_time system variable:       server-system-variables.
                                                             (line 2201)
* LONGBLOB data type:                    string-type-overview.
                                                             (line  218)
* LONGTEXT data type:                    string-type-overview.
                                                             (line  228)
* LOOP:                                  loop-statement.     (line    6)
* lost connection errors:                error-lost-connection.
                                                             (line    6)
* low-priority option, mysqlimport:      mysqlimport.        (line  209)
* low-priority-updates option, mysqld:   server-options.     (line  985)
* low_priority_updates system variable:  server-system-variables.
                                                             (line 2233)
* LOWER():                               string-functions.   (line  412)
* lower_case_file_system system variable: server-system-variables.
                                                             (line 2254)
* lower_case_table_names system variable: server-system-variables.
                                                             (line 2271)
* LPAD():                                string-functions.   (line  436)
* LTRIM():                               string-functions.   (line  447)
* Mac OS X:                              connector-odbc.     (line   17)
* Mac OS X, installation:                mac-os-x-installation.
                                                             (line    6)
* mailing list address:                  introduction.       (line   77)
* mailing lists:                         mailing-lists.      (line   10)
* mailing lists, archive location:       mailing-lists.      (line   10)
* mailing lists, guidelines:             mailing-list-use.   (line    6)
* main features of MySQL:                features.           (line    6)
* maintaining, log files:                log-file-maintenance.
                                                             (line    6)
* maintaining, tables:                   maintenance-schedule.
                                                             (line    6)
* maintenance, tables:                   mysqlcheck.         (line    6)
* make_binary_distribution:              programs-overview.  (line   70)
* MAKE_SET():                            string-functions.   (line  456)
* make_win_bin_dist <1>:                 make-win-bin-dist.  (line    6)
* make_win_bin_dist:                     programs-overview.  (line   76)
* make_win_bin_dist, debug option:       make-win-bin-dist.  (line   37)
* make_win_bin_dist, embedded option:    make-win-bin-dist.  (line   42)
* make_win_bin_dist, exe-suffix option:  make-win-bin-dist.  (line   47)
* make_win_bin_dist, no-debug option:    make-win-bin-dist.  (line   53)
* make_win_bin_dist, no-embedded option: make-win-bin-dist.  (line   57)
* make_win_bin_dist, only-debug option:  make-win-bin-dist.  (line   61)
* MAKEDATE():                            date-and-time-functions.
                                                             (line  643)
* MAKETIME():                            date-and-time-functions.
                                                             (line  655)
* Making temp file, thread state:        slave-sql-thread-states.
                                                             (line   25)
* manual, available formats:             manual-info.        (line   30)
* manual, online location:               manual-info.        (line    6)
* manual, syntax conventions:            manual-conventions. (line    8)
* manual, typographical conventions:     manual-conventions. (line    8)
* master-data option, mysqldump:         mysqldump.          (line  556)
* master-info-file option, mysqld:       replication-options-slave.
                                                             (line  140)
* master-retry-count option, mysqld:     replication-options-slave.
                                                             (line  146)
* MASTER_POS_WAIT() <1>:                 master-pos-wait.    (line    6)
* MASTER_POS_WAIT():                     miscellaneous-functions.
                                                             (line  144)
* MATCH ... AGAINST():                   fulltext-search.    (line   15)
* matching, patterns:                    pattern-matching.   (line    6)
* math:                                  precision-math.     (line   14)
* mathematical functions:                mathematical-functions.
                                                             (line   52)
* MAX():                                 group-by-functions. (line  179)
* MAX(DISTINCT):                         group-by-functions. (line  179)
* max-binlog-dump-events option, mysqld: replication-options-binary-log.
                                                             (line  272)
* max-record-length option, myisamchk:   myisamchk-repair-options.
                                                             (line   54)
* max-relay-log-size option, mysqld:     replication-options-slave.
                                                             (line  160)
* max_allowed_packet system variable:    server-system-variables.
                                                             (line 2301)
* max_allowed_packet variable:           mysql-command-options.
                                                             (line  542)
* max_binlog_cache_size system variable: replication-options-binary-log.
                                                             (line  402)
* max_binlog_size system variable:       replication-options-binary-log.
                                                             (line  430)
* max_connect_errors system variable:    server-system-variables.
                                                             (line 2343)
* max_connections system variable:       server-system-variables.
                                                             (line 2369)
* MAX_CONNECTIONS_PER_HOUR:              user-resources.     (line    6)
* max_delayed_threads system variable:   server-system-variables.
                                                             (line 2400)
* max_error_count system variable:       server-system-variables.
                                                             (line 2426)
* max_heap_table_size system variable:   server-system-variables.
                                                             (line 2445)
* max_insert_delayed_threads system variable: server-system-variables.
                                                             (line 2482)
* max_join_size system variable:         server-system-variables.
                                                             (line 2492)
* max_join_size variable:                mysql-command-options.
                                                             (line  547)
* max_length_for_sort_data system variable: server-system-variables.
                                                             (line 2528)
* max_prepared_stmt_count system variable: server-system-variables.
                                                             (line 2546)
* MAX_QUERIES_PER_HOUR:                  user-resources.     (line    6)
* max_relay_log_size system variable:    server-system-variables.
                                                             (line 2572)
* max_seeks_for_key system variable:     server-system-variables.
                                                             (line 2598)
* max_sort_length system variable:       server-system-variables.
                                                             (line 2627)
* max_sp_recursion_depth system variable: server-system-variables.
                                                             (line 2646)
* max_tmp_tables system variable:        server-system-variables.
                                                             (line 2671)
* MAX_UPDATES_PER_HOUR:                  user-resources.     (line    6)
* MAX_USER_CONNECTIONS:                  user-resources.     (line    6)
* max_user_connections system variable:  server-system-variables.
                                                             (line 2695)
* max_write_lock_count system variable:  server-system-variables.
                                                             (line 2718)
* MAXDB SQL mode:                        server-sql-mode.    (line  452)
* maximum memory used:                   mysqladmin.         (line  221)
* maximums, maximum columns per table:   column-count-limit. (line    6)
* maximums, maximum tables per join:     joins-limits.       (line    6)
* MBR:                                   relations-on-geometry-mbr.
                                                             (line    6)
* MBRContains():                         relations-on-geometry-mbr.
                                                             (line   10)
* MBRDisjoint():                         relations-on-geometry-mbr.
                                                             (line   25)
* MBREqual():                            relations-on-geometry-mbr.
                                                             (line   30)
* MBRIntersects():                       relations-on-geometry-mbr.
                                                             (line   35)
* MBROverlaps():                         relations-on-geometry-mbr.
                                                             (line   40)
* MBRTouches():                          relations-on-geometry-mbr.
                                                             (line   48)
* MBRWithin():                           relations-on-geometry-mbr.
                                                             (line   56)
* MD5():                                 encryption-functions.
                                                             (line  223)
* medium-check option, myisamchk:        myisamchk-check-options.
                                                             (line   44)
* medium-check option, mysqlcheck:       mysqlcheck.         (line  279)
* MEDIUMBLOB data type:                  string-type-overview.
                                                             (line  203)
* MEDIUMINT data type:                   numeric-type-overview.
                                                             (line  113)
* MEDIUMTEXT data type:                  string-type-overview.
                                                             (line  210)
* memlock option, mysqld:                server-options.     (line 1033)
* MEMORY storage engine <1>:             memory-storage-engine.
                                                             (line    6)
* MEMORY storage engine:                 storage-engines.    (line   24)
* MEMORY storage engine, and replication: replication-features-memory.
                                                             (line    6)
* memory usage, myisamchk:               myisamchk-memory.   (line    6)
* memory use <1>:                        memory-use.         (line    6)
* memory use:                            mysqladmin.         (line  215)
* MERGE storage engine <1>:              merge-storage-engine.
                                                             (line   10)
* MERGE storage engine:                  storage-engines.    (line   24)
* MERGE tables, defined:                 merge-storage-engine.
                                                             (line   10)
* metadata, database:                    information-schema. (line   39)
* metadata, stored routines:             stored-routines-metadata.
                                                             (line    6)
* metadata, triggers:                    trigger-metadata.   (line    6)
* metadata, views:                       view-metadata.      (line    6)
* metadata-extra option, mysqlbackup:    mysqlbackup.        (line  115)
* metadata-statements option, mysqlbackup: mysqlbackup.      (line  119)
* method option, mysqlhotcopy:           mysqlhotcopy.       (line  116)
* methods, locking:                      internal-locking.   (line    6)
* MICROSECOND():                         date-and-time-functions.
                                                             (line  663)
* Microsoft Access:                      connector-odbc-usagenotes-apptips-microsoft-access.
                                                             (line    6)
* Microsoft ADO:                         connector-odbc-usagenotes-apptips-microsoft-ado.
                                                             (line    6)
* Microsoft Excel:                       connector-odbc-usagenotes-apptips-microsoft-excel.
                                                             (line    6)
* Microsoft Visual Basic:                connector-odbc-usagenotes-apptips-microsoft-visualbasic.
                                                             (line    6)
* Microsoft Visual InterDev:             connector-odbc-usagenotes-apptips-microsoft-visualinterdev.
                                                             (line    6)
* MID():                                 string-functions.   (line  473)
* MIN():                                 group-by-functions. (line  199)
* MIN(DISTINCT):                         group-by-functions. (line  199)
* min-examined-row-limit option, mysqld: server-options.     (line 1008)
* min_examined_row_limit system variable: server-system-variables.
                                                             (line 2742)
* Minimum Bounding Rectangle:            relations-on-geometry-mbr.
                                                             (line    6)
* minus, unary (-):                      arithmetic-functions.
                                                             (line   58)
* MINUTE():                              date-and-time-functions.
                                                             (line  673)
* mirror sites:                          getting-mysql.      (line    6)
* miscellaneous functions:               miscellaneous-functions.
                                                             (line    6)
* MIT-pthreads:                          mit-pthreads.       (line    6)
* MLineFromText():                       gis-wkt-functions.  (line   30)
* MLineFromWKB():                        gis-wkb-functions.  (line   31)
* MOD (modulo):                          mathematical-functions.
                                                             (line  301)
* MOD():                                 mathematical-functions.
                                                             (line  301)
* modes, batch:                          batch-mode.         (line    6)
* modulo (%):                            mathematical-functions.
                                                             (line  301)
* modulo (MOD):                          mathematical-functions.
                                                             (line  301)
* monitor, terminal:                     tutorial.           (line   17)
* Monitors, InnoDB <1>:                  innodb-troubleshooting-datadict.
                                                             (line   57)
* Monitors, InnoDB <2>:                  innodb-troubleshooting.
                                                             (line   20)
* Monitors, InnoDB <3>:                  innodb-monitors.    (line   12)
* Monitors, InnoDB <4>:                  innodb-file-space.  (line   66)
* Monitors, InnoDB:                      innodb-backup.      (line  102)
* Mono:                                  connector-net.      (line   15)
* MONTH():                               date-and-time-functions.
                                                             (line  680)
* MONTHNAME():                           date-and-time-functions.
                                                             (line  689)
* MPointFromText():                      gis-wkt-functions.  (line   35)
* MPointFromWKB():                       gis-wkb-functions.  (line   36)
* MPolyFromText():                       gis-wkt-functions.  (line   40)
* MPolyFromWKB():                        gis-wkb-functions.  (line   41)
* mSQL compatibility:                    regexp.             (line   30)
* msql2mysql:                            msql2mysql.         (line    6)
* MSSQL SQL mode:                        server-sql-mode.    (line  458)
* multi mysqld:                          mysqld-multi.       (line    6)
* multi-byte character sets:             cannot-initialize-character-set.
                                                             (line    6)
* multi-byte characters:                 multi-byte-characters.
                                                             (line    6)
* multi-column indexes:                  multiple-column-indexes.
                                                             (line    6)
* Multi-Range Read, optimization:        mrr-optimization.   (line    6)
* multi_range_count system variable:     server-system-variables.
                                                             (line 3264)
* MULTILINESTRING data type:             mysql-spatial-datatypes.
                                                             (line    6)
* MultiLineString():                     gis-mysql-specific-functions.
                                                             (line   27)
* MultiLineStringFromText():             gis-wkt-functions.  (line   30)
* MultiLineStringFromWKB():              gis-wkb-functions.  (line   31)
* multiple servers:                      multiple-servers.   (line   12)
* multiple-part index:                   create-index.       (line    6)
* multiplication (*):                    arithmetic-functions.
                                                             (line   72)
* MULTIPOINT data type:                  mysql-spatial-datatypes.
                                                             (line    6)
* MultiPoint():                          gis-mysql-specific-functions.
                                                             (line   33)
* MultiPointFromText():                  gis-wkt-functions.  (line   35)
* MultiPointFromWKB():                   gis-wkb-functions.  (line   36)
* MULTIPOLYGON data type:                mysql-spatial-datatypes.
                                                             (line    6)
* MultiPolygon():                        gis-mysql-specific-functions.
                                                             (line   38)
* MultiPolygonFromText():                gis-wkt-functions.  (line   40)
* MultiPolygonFromWKB():                 gis-wkb-functions.  (line   41)
* My, derivation:                        history.            (line    6)
* my.cnf file:                           replication-features.
                                                             (line   38)
* my_bool C type:                        c-api-datatypes.    (line   63)
* my_bool values, printing:              c-api-datatypes.    (line   63)
* my_init():                             my-init.            (line    6)
* my_print_defaults <1>:                 my-print-defaults.  (line    6)
* my_print_defaults:                     programs-overview.  (line  244)
* my_print_defaults, config-file option: my-print-defaults.  (line   29)
* my_print_defaults, debug option:       my-print-defaults.  (line   35)
* my_print_defaults, defaults-extra-file option: my-print-defaults.
                                                             (line   41)
* my_print_defaults, defaults-file option: my-print-defaults.
                                                             (line   31)
* my_print_defaults, defaults-group-suffix option: my-print-defaults.
                                                             (line   48)
* my_print_defaults, extra-file option:  my-print-defaults.  (line   43)
* my_print_defaults, help option:        my-print-defaults.  (line   25)
* my_print_defaults, no-defaults option: my-print-defaults.  (line   53)
* my_print_defaults, verbose option:     my-print-defaults.  (line   57)
* my_print_defaults, version option:     my-print-defaults.  (line   61)
* my_ulonglong C type:                   c-api-datatypes.    (line   49)
* my_ulonglong values, printing:         c-api-datatypes.    (line   49)
* MyISAM key cache:                      myisam-key-cache.   (line   15)
* MyISAM storage engine <1>:             myisam-storage-engine.
                                                             (line   13)
* MyISAM storage engine:                 storage-engines.    (line   24)
* MyISAM, compressed tables <1>:         compressed-format.  (line    6)
* MyISAM, compressed tables:             myisampack.         (line    6)
* myisam-block-size option, mysqld:      server-options.     (line 1074)
* myisam-recover option, mysqld <1>:     myisam-start.       (line   34)
* myisam-recover option, mysqld:         server-options.     (line 1086)
* myisam_block_size myisamchk variable:  myisamchk-general-options.
                                                             (line   53)
* myisam_data_pointer_size system variable: server-system-variables.
                                                             (line 2765)
* myisam_ftdump <1>:                     myisam-ftdump.      (line    6)
* myisam_ftdump:                         programs-overview.  (line  157)
* myisam_ftdump, count option:           myisam-ftdump.      (line   52)
* myisam_ftdump, dump option:            myisam-ftdump.      (line   56)
* myisam_ftdump, help option:            myisam-ftdump.      (line   48)
* myisam_ftdump, length option:          myisam-ftdump.      (line   60)
* myisam_ftdump, stats option:           myisam-ftdump.      (line   64)
* myisam_ftdump, verbose option:         myisam-ftdump.      (line   69)
* myisam_max_sort_file_size system variable: server-system-variables.
                                                             (line 2784)
* myisam_recover_options system variable: server-system-variables.
                                                             (line 2809)
* myisam_repair_threads system variable: server-system-variables.
                                                             (line 2818)
* myisam_sort_buffer_size system variable: server-system-variables.
                                                             (line 2847)
* myisam_stats_method system variable:   server-system-variables.
                                                             (line 2878)
* myisam_use_mmap system variable:       server-system-variables.
                                                             (line 2912)
* myisamchk <1>:                         myisamchk.          (line   14)
* myisamchk <2>:                         programs-overview.  (line  162)
* myisamchk:                             configure-options.  (line  448)
* myisamchk, analyze option:             myisamchk-other-options.
                                                             (line    9)
* myisamchk, backup option:              myisamchk-repair-options.
                                                             (line    9)
* myisamchk, block-search option:        myisamchk-other-options.
                                                             (line   24)
* myisamchk, character-sets-dir option:  myisamchk-repair-options.
                                                             (line   13)
* myisamchk, check option:               myisamchk-check-options.
                                                             (line    9)
* myisamchk, check-only-changed option:  myisamchk-check-options.
                                                             (line   14)
* myisamchk, correct-checksum option:    myisamchk-repair-options.
                                                             (line   18)
* myisamchk, data-file-length option:    myisamchk-repair-options.
                                                             (line   22)
* myisamchk, debug option:               myisamchk-general-options.
                                                             (line   21)
* myisamchk, description option:         myisamchk-other-options.
                                                             (line   28)
* myisamchk, example output:             table-info.         (line   37)
* myisamchk, extend-check option <1>:    myisamchk-repair-options.
                                                             (line   27)
* myisamchk, extend-check option:        myisamchk-check-options.
                                                             (line   18)
* myisamchk, fast option:                myisamchk-check-options.
                                                             (line   30)
* myisamchk, force option <1>:           myisamchk-repair-options.
                                                             (line   33)
* myisamchk, force option:               myisamchk-check-options.
                                                             (line   34)
* myisamchk, HELP option:                myisamchk-general-options.
                                                             (line   16)
* myisamchk, help option:                myisamchk-general-options.
                                                             (line   11)
* myisamchk, information option:         myisamchk-check-options.
                                                             (line   40)
* myisamchk, keys-used option:           myisamchk-repair-options.
                                                             (line   38)
* myisamchk, max-record-length option:   myisamchk-repair-options.
                                                             (line   54)
* myisamchk, medium-check option:        myisamchk-check-options.
                                                             (line   44)
* myisamchk, no-symlinks option:         myisamchk-repair-options.
                                                             (line   47)
* myisamchk, options:                    myisamchk-general-options.
                                                             (line    6)
* myisamchk, parallel-recover option:    myisamchk-repair-options.
                                                             (line   59)
* myisamchk, quick option:               myisamchk-repair-options.
                                                             (line   65)
* myisamchk, read-only option:           myisamchk-check-options.
                                                             (line   50)
* myisamchk, recover option:             myisamchk-repair-options.
                                                             (line   71)
* myisamchk, safe-recover option:        myisamchk-repair-options.
                                                             (line   84)
* myisamchk, set-auto-increment[ option: myisamchk-other-options.
                                                             (line   32)
* myisamchk, set-character-set option:   myisamchk-repair-options.
                                                             (line   97)
* myisamchk, set-collation option:       myisamchk-repair-options.
                                                             (line  102)
* myisamchk, silent option:              myisamchk-general-options.
                                                             (line   27)
* myisamchk, sort-index option:          myisamchk-other-options.
                                                             (line   40)
* myisamchk, sort-records option:        myisamchk-other-options.
                                                             (line   45)
* myisamchk, sort-recover option:        myisamchk-repair-options.
                                                             (line  108)
* myisamchk, tmpdir option:              myisamchk-repair-options.
                                                             (line  113)
* myisamchk, unpack option:              myisamchk-repair-options.
                                                             (line  123)
* myisamchk, update-state option:        myisamchk-check-options.
                                                             (line   57)
* myisamchk, verbose option:             myisamchk-general-options.
                                                             (line   32)
* myisamchk, version option:             myisamchk-general-options.
                                                             (line   38)
* myisamchk, wait option:                myisamchk-general-options.
                                                             (line   42)
* myisamlog <1>:                         myisamlog.          (line    6)
* myisamlog:                             programs-overview.  (line  167)
* myisampack <1>:                        compressed-format.  (line    6)
* myisampack <2>:                        silent-column-changes.
                                                             (line   63)
* myisampack <3>:                        myisampack.         (line    6)
* myisampack:                            programs-overview.  (line  172)
* myisampack, backup option:             myisampack.         (line   53)
* myisampack, character-sets-dir option: myisampack.         (line   58)
* myisampack, debug option:              myisampack.         (line   63)
* myisampack, force option:              myisampack.         (line   68)
* myisampack, help option:               myisampack.         (line   49)
* myisampack, join option:               myisampack.         (line   80)
* myisampack, silent option:             myisampack.         (line   95)
* myisampack, test option:               myisampack.         (line   99)
* myisampack, tmpdir option:             myisampack.         (line  103)
* myisampack, verbose option:            myisampack.         (line  108)
* myisampack, version option:            myisampack.         (line  113)
* myisampack, wait option:               myisampack.         (line  117)
* MyODBC:                                connector-odbc.     (line   17)
* mysql <1>:                             mysql.              (line   14)
* mysql:                                 programs-overview.  (line  111)
* mysql \. (command for reading from text files) <1>: batch-commands.
                                                             (line    6)
* mysql \. (command for reading from text files): batch-mode.
                                                             (line   90)
* MySQL binary distribution:             which-version.      (line   19)
* MYSQL C type:                          c-api-datatypes.    (line   10)
* MySQL Cluster, FAQ:                    faqs-mysql-cluster. (line    6)
* mysql command options:                 mysql-command-options.
                                                             (line    6)
* mysql commands, list of:               mysql-commands.     (line   11)
* MySQL Dolphin name:                    history.            (line    6)
* MySQL history:                         history.            (line    6)
* mysql history file:                    mysql-command-options.
                                                             (line  562)
* MySQL mailing lists:                   mailing-lists.      (line   10)
* MySQL name:                            history.            (line    6)
* mysql prompt command:                  mysql-commands.     (line  282)
* MySQL server, mysqld <1>:              mysqld-server.      (line   19)
* MySQL server, mysqld:                  mysqld.             (line    6)
* mysql source (command for reading from text files) <1>: batch-commands.
                                                             (line    6)
* mysql source (command for reading from text files): batch-mode.
                                                             (line   90)
* MySQL source distribution:             which-version.      (line   19)
* MySQL storage engines:                 storage-engines.    (line   24)
* MySQL system tables, and replication:  replication-features-mysqldb.
                                                             (line    6)
* MySQL version:                         getting-mysql.      (line    6)
* MySQL++:                               apis-cplusplus.     (line    6)
* mysql, auto-rehash option:             mysql-command-options.
                                                             (line  134)
* mysql, auto-vertical-output option:    mysql-command-options.
                                                             (line  148)
* mysql, batch option:                   mysql-command-options.
                                                             (line  155)
* mysql, character-sets-dir option:      mysql-command-options.
                                                             (line  165)
* mysql, charset command:                mysql-commands.     (line   61)
* mysql, clear command:                  mysql-commands.     (line   69)
* mysql, column-names option:            mysql-command-options.
                                                             (line  170)
* mysql, column-type-info option:        mysql-command-options.
                                                             (line  174)
* mysql, comments option:                mysql-command-options.
                                                             (line  178)
* mysql, compress option:                mysql-command-options.
                                                             (line  185)
* mysql, connect command:                mysql-commands.     (line   74)
* mysql, database option:                mysql-command-options.
                                                             (line  190)
* mysql, debug option:                   mysql-command-options.
                                                             (line  194)
* mysql, debug-check option:             mysql-command-options.
                                                             (line  199)
* mysql, debug-info option:              mysql-command-options.
                                                             (line  203)
* mysql, default-character-set option:   mysql-command-options.
                                                             (line  208)
* MySQL, defined:                        what-is-mysql.      (line    6)
* mysql, delimiter command:              mysql-commands.     (line   81)
* mysql, delimiter option:               mysql-command-options.
                                                             (line  213)
* mysql, disable named commands:         mysql-command-options.
                                                             (line  218)
* mysql, edit command:                   mysql-commands.     (line  107)
* mysql, ego command:                    mysql-commands.     (line  116)
* mysql, execute option:                 mysql-command-options.
                                                             (line  226)
* mysql, exit command:                   mysql-commands.     (line  121)
* mysql, force option:                   mysql-command-options.
                                                             (line  232)
* mysql, go command:                     mysql-commands.     (line  125)
* mysql, help command:                   mysql-commands.     (line   51)
* mysql, help option:                    mysql-command-options.
                                                             (line  130)
* mysql, host option:                    mysql-command-options.
                                                             (line  236)
* mysql, html option:                    mysql-command-options.
                                                             (line  240)
* mysql, i-am-a-dummy option:            mysql-command-options.
                                                             (line  393)
* mysql, ignore-spaces option:           mysql-command-options.
                                                             (line  244)
* MySQL, introduction:                   what-is-mysql.      (line    6)
* mysql, line-numbers option:            mysql-command-options.
                                                             (line  250)
* mysql, local-infile option:            mysql-command-options.
                                                             (line  255)
* mysql, named-commands option:          mysql-command-options.
                                                             (line  270)
* mysql, no-auto-rehash option:          mysql-command-options.
                                                             (line  277)
* mysql, no-beep option:                 mysql-command-options.
                                                             (line  283)
* mysql, no-named-commands option:       mysql-command-options.
                                                             (line  287)
* mysql, no-pager option:                mysql-command-options.
                                                             (line  291)
* mysql, no-tee option:                  mysql-command-options.
                                                             (line  295)
* mysql, nopager command:                mysql-commands.     (line  129)
* mysql, notee command:                  mysql-commands.     (line  135)
* mysql, nowarning command:              mysql-commands.     (line  140)
* mysql, one-database option:            mysql-command-options.
                                                             (line  300)
* mysql, pager command:                  mysql-commands.     (line  144)
* mysql, pager option:                   mysql-command-options.
                                                             (line  306)
* mysql, password option:                mysql-command-options.
                                                             (line  315)
* mysql, pipe option:                    mysql-command-options.
                                                             (line  326)
* mysql, port option:                    mysql-command-options.
                                                             (line  332)
* mysql, print command:                  mysql-commands.     (line  165)
* mysql, prompt command:                 mysql-commands.     (line  169)
* mysql, prompt option:                  mysql-command-options.
                                                             (line  336)
* MySQL, pronunciation:                  what-is-mysql.      (line   87)
* mysql, protocol option:                mysql-command-options.
                                                             (line  342)
* mysql, quick option:                   mysql-command-options.
                                                             (line  349)
* mysql, quit command:                   mysql-commands.     (line  178)
* mysql, raw option:                     mysql-command-options.
                                                             (line  355)
* mysql, reconnect option:               mysql-command-options.
                                                             (line  386)
* mysql, rehash command:                 mysql-commands.     (line  182)
* mysql, safe-updates option:            mysql-command-options.
                                                             (line  393)
* mysql, secure-auth option:             mysql-command-options.
                                                             (line  401)
* mysql, show-warnings option:           mysql-command-options.
                                                             (line  413)
* mysql, sigint-ignore option:           mysql-command-options.
                                                             (line  418)
* mysql, silent option:                  mysql-command-options.
                                                             (line  422)
* mysql, skip-column-names option:       mysql-command-options.
                                                             (line  431)
* mysql, skip-line-numbers option:       mysql-command-options.
                                                             (line  436)
* mysql, socket option:                  mysql-command-options.
                                                             (line  442)
* mysql, source command:                 mysql-commands.     (line  188)
* mysql, SSL options:                    mysql-command-options.
                                                             (line  447)
* mysql, status command:                 mysql-commands.     (line  194)
* mysql, system command:                 mysql-commands.     (line  201)
* mysql, table option:                   mysql-command-options.
                                                             (line  453)
* mysql, tee command:                    mysql-commands.     (line  207)
* mysql, tee option:                     mysql-command-options.
                                                             (line  459)
* mysql, unbuffered option:              mysql-command-options.
                                                             (line  465)
* MySQL, upgrading:                      mysql-upgrade.      (line    6)
* mysql, use command:                    mysql-commands.     (line  221)
* mysql, user option:                    mysql-command-options.
                                                             (line  469)
* mysql, verbose option:                 mysql-command-options.
                                                             (line  473)
* mysql, version option:                 mysql-command-options.
                                                             (line  480)
* mysql, vertical option:                mysql-command-options.
                                                             (line  484)
* mysql, wait option:                    mysql-command-options.
                                                             (line  490)
* mysql, warnings command:               mysql-commands.     (line  225)
* mysql, xml option:                     mysql-command-options.
                                                             (line  495)
* mysql.event table:                     events-privileges.  (line  138)
* mysql.server <1>:                      mysql-server.       (line    6)
* mysql.server:                          programs-overview.  (line   48)
* mysql.server, basedir option:          mysql-server.       (line   36)
* mysql.server, datadir option:          mysql-server.       (line   40)
* mysql.server, pid-file option:         mysql-server.       (line   44)
* mysql.server, service-startup-timeout option: mysql-server.
                                                             (line   49)
* mysql.server, use-mysqld_safe option:  mysql-server.       (line   57)
* mysql.server, user option:             mysql-server.       (line   62)
* mysql.sock, changing location of:      configure-options.  (line  342)
* mysql.sock, protection:                problems-with-mysql-sock.
                                                             (line    6)
* MYSQL323 SQL mode:                     server-sql-mode.    (line  463)
* MYSQL40 SQL mode:                      server-sql-mode.    (line  467)
* mysql_affected_rows():                 mysql-affected-rows.
                                                             (line    6)
* mysql_autocommit():                    mysql-autocommit.   (line    6)
* MYSQL_BIND C type:                     c-api-prepared-statement-datatypes.
                                                             (line   43)
* mysql_change_user():                   mysql-change-user.  (line    6)
* mysql_character_set_name():            mysql-character-set-name.
                                                             (line    6)
* mysql_close():                         mysql-close.        (line    6)
* mysql_commit():                        mysql-commit.       (line    6)
* mysql_config:                          mysql-config.       (line    6)
* mysql_config, cflags option:           mysql-config.       (line   11)
* mysql_config, embedded option:         mysql-config.       (line   24)
* mysql_config, include option:          mysql-config.       (line   20)
* mysql_config, libmysqld-libs option:   mysql-config.       (line   24)
* mysql_config, libs option:             mysql-config.       (line   29)
* mysql_config, libs_r option:           mysql-config.       (line   34)
* mysql_config, plugindir option:        mysql-config.       (line   39)
* mysql_config, port option:             mysql-config.       (line   44)
* mysql_config, socket option:           mysql-config.       (line   48)
* mysql_config, version option:          mysql-config.       (line   52)
* mysql_connect():                       mysql-connect.      (line    6)
* mysql_convert_table_format <1>:        mysql-convert-table-format.
                                                             (line    6)
* mysql_convert_table_format:            programs-overview.  (line  198)
* mysql_convert_table_format, force option: mysql-convert-table-format.
                                                             (line   28)
* mysql_convert_table_format, help option: mysql-convert-table-format.
                                                             (line   24)
* mysql_convert_table_format, host option: mysql-convert-table-format.
                                                             (line   32)
* mysql_convert_table_format, password option: mysql-convert-table-format.
                                                             (line   36)
* mysql_convert_table_format, port option: mysql-convert-table-format.
                                                             (line   46)
* mysql_convert_table_format, socket option: mysql-convert-table-format.
                                                             (line   50)
* mysql_convert_table_format, type option: mysql-convert-table-format.
                                                             (line   54)
* mysql_convert_table_format, user option: mysql-convert-table-format.
                                                             (line   65)
* mysql_convert_table_format, verbose option: mysql-convert-table-format.
                                                             (line   69)
* mysql_convert_table_format, version option: mysql-convert-table-format.
                                                             (line   73)
* mysql_create_db():                     mysql-create-db.    (line    6)
* mysql_data_seek():                     mysql-data-seek.    (line    6)
* MYSQL_DEBUG environment variable <1>:  debugging-client.   (line   10)
* MYSQL_DEBUG environment variable <2>:  programs-overview.  (line  291)
* MYSQL_DEBUG environment variable:      environment-variables.
                                                             (line   18)
* mysql_debug():                         mysql-debug.        (line    6)
* mysql_drop_db():                       mysql-drop-db.      (line    6)
* mysql_dump_debug_info():               mysql-dump-debug-info.
                                                             (line    6)
* mysql_eof():                           mysql-eof.          (line    6)
* mysql_errno():                         mysql-errno.        (line    6)
* mysql_error():                         mysql-error.        (line    6)
* mysql_escape_string():                 mysql-escape-string.
                                                             (line    6)
* mysql_fetch_field():                   mysql-fetch-field.  (line    6)
* mysql_fetch_field_direct():            mysql-fetch-field-direct.
                                                             (line    6)
* mysql_fetch_fields():                  mysql-fetch-fields. (line    6)
* mysql_fetch_lengths():                 mysql-fetch-lengths.
                                                             (line    6)
* mysql_fetch_row():                     mysql-fetch-row.    (line    6)
* MYSQL_FIELD C type:                    c-api-datatypes.    (line   34)
* mysql_field_count() <1>:               mysql-num-fields.   (line    6)
* mysql_field_count():                   mysql-field-count.  (line    6)
* MYSQL_FIELD_OFFSET C type:             c-api-datatypes.    (line   43)
* mysql_field_seek():                    mysql-field-seek.   (line    6)
* mysql_field_tell():                    mysql-field-tell.   (line    6)
* mysql_find_rows <1>:                   mysql-find-rows.    (line    6)
* mysql_find_rows:                       programs-overview.  (line  203)
* mysql_find_rows, help option:          mysql-find-rows.    (line   31)
* mysql_find_rows, regexp option:        mysql-find-rows.    (line   35)
* mysql_find_rows, rows option:          mysql-find-rows.    (line   39)
* mysql_find_rows, skip-use-db option:   mysql-find-rows.    (line   43)
* mysql_find_rows, start_row option:     mysql-find-rows.    (line   47)
* mysql_fix_extensions <1>:              mysql-fix-extensions.
                                                             (line    6)
* mysql_fix_extensions:                  programs-overview.  (line  209)
* mysql_fix_privilege_tables:            mysql-fix-privilege-tables.
                                                             (line    6)
* mysql_free_result():                   mysql-free-result.  (line    6)
* mysql_get_character_set_info():        mysql-get-character-set-info.
                                                             (line    6)
* mysql_get_client_info():               mysql-get-client-info.
                                                             (line    6)
* mysql_get_client_version():            mysql-get-client-version.
                                                             (line    6)
* mysql_get_host_info():                 mysql-get-host-info.
                                                             (line    6)
* mysql_get_proto_info():                mysql-get-proto-info.
                                                             (line    6)
* mysql_get_server_info():               mysql-get-server-info.
                                                             (line    6)
* mysql_get_server_version():            mysql-get-server-version.
                                                             (line    6)
* mysql_get_ssl_cipher():                mysql-get-ssl-cipher.
                                                             (line    6)
* MYSQL_GROUP_SUFFIX environment variable: environment-variables.
                                                             (line   18)
* mysql_hex_string():                    mysql-hex-string.   (line    6)
* MYSQL_HISTFILE environment variable <1>: mysql-command-options.
                                                             (line  562)
* MYSQL_HISTFILE environment variable:   environment-variables.
                                                             (line   18)
* MYSQL_HOME environment variable:       environment-variables.
                                                             (line   18)
* MYSQL_HOST environment variable <1>:   connecting.         (line  232)
* MYSQL_HOST environment variable:       environment-variables.
                                                             (line   18)
* mysql_info() <1>:                      mysql-info.         (line    6)
* mysql_info() <2>:                      update.             (line   75)
* mysql_info() <3>:                      load-data.          (line  642)
* mysql_info() <4>:                      insert.             (line  202)
* mysql_info():                          alter-table.        (line  663)
* mysql_init():                          mysql-init.         (line    6)
* mysql_insert_id() <1>:                 mysql-insert-id.    (line    6)
* mysql_insert_id() <2>:                 insert.             (line  206)
* mysql_insert_id():                     ansi-diff-transactions.
                                                             (line  165)
* mysql_install_db <1>:                  mysql-install-db.   (line    6)
* mysql_install_db <2>:                  programs-overview.  (line   82)
* mysql_install_db:                      mysql-install-db-problems.
                                                             (line    6)
* mysql_install_db, basedir option:      mysql-install-db.   (line   42)
* mysql_install_db, datadir option:      mysql-install-db.   (line   52)
* mysql_install_db, force option:        mysql-install-db.   (line   46)
* mysql_install_db, ldata option:        mysql-install-db.   (line   52)
* mysql_install_db, rpm option:          mysql-install-db.   (line   56)
* mysql_install_db, skip-name-resolve option: mysql-install-db.
                                                             (line   61)
* mysql_install_db, srcdir option:       mysql-install-db.   (line   66)
* mysql_install_db, user option:         mysql-install-db.   (line   73)
* mysql_install_db, verbose option:      mysql-install-db.   (line   82)
* mysql_install_db, windows option:      mysql-install-db.   (line   86)
* mysql_kill():                          mysql-kill.         (line    6)
* mysql_library_end():                   mysql-library-end.  (line    6)
* mysql_library_init():                  mysql-library-init. (line    6)
* mysql_list_dbs():                      mysql-list-dbs.     (line    6)
* mysql_list_fields():                   mysql-list-fields.  (line    6)
* mysql_list_processes():                mysql-list-processes.
                                                             (line    6)
* mysql_list_tables():                   mysql-list-tables.  (line    6)
* mysql_more_results():                  mysql-more-results. (line    6)
* mysql_next_result():                   mysql-next-result.  (line    6)
* mysql_num_fields():                    mysql-num-fields.   (line    6)
* mysql_num_rows():                      mysql-num-rows.     (line    6)
* mysql_options():                       mysql-options.      (line    6)
* mysql_ping():                          mysql-ping.         (line    6)
* MYSQL_PS1 environment variable:        environment-variables.
                                                             (line   18)
* MYSQL_PWD environment variable <1>:    connecting.         (line  232)
* MYSQL_PWD environment variable <2>:    programs-overview.  (line  291)
* MYSQL_PWD environment variable:        environment-variables.
                                                             (line   18)
* mysql_query() <1>:                     c-api-problems.     (line   13)
* mysql_query():                         mysql-query.        (line    6)
* mysql_real_connect():                  mysql-real-connect. (line    6)
* mysql_real_escape_string() <1>:        mysql-real-escape-string.
                                                             (line    6)
* mysql_real_escape_string():            string-syntax.      (line  140)
* mysql_real_query():                    mysql-real-query.   (line    6)
* mysql_refresh():                       mysql-refresh.      (line    6)
* mysql_reload():                        mysql-reload.       (line    6)
* MYSQL_RES C type:                      c-api-datatypes.    (line   17)
* mysql_rollback():                      mysql-rollback.     (line    6)
* MYSQL_ROW C type:                      c-api-datatypes.    (line   25)
* mysql_row_seek():                      mysql-row-seek.     (line    6)
* mysql_row_tell():                      mysql-row-tell.     (line    6)
* mysql_secure_installation <1>:         mysql-secure-installation.
                                                             (line    6)
* mysql_secure_installation:             programs-overview.  (line   90)
* mysql_select_db():                     mysql-select-db.    (line    6)
* mysql_server_end():                    mysql-server-end.   (line    6)
* mysql_server_init():                   mysql-server-init.  (line    6)
* mysql_set_character_set():             mysql-set-character-set.
                                                             (line    6)
* mysql_set_local_infile_default():      mysql-set-local-infile-default.
                                                             (line    6)
* mysql_set_server_option():             mysql-set-server-option.
                                                             (line    6)
* mysql_setpermission <1>:               mysql-setpermission.
                                                             (line    6)
* mysql_setpermission:                   programs-overview.  (line  216)
* mysql_setpermission, help option:      mysql-setpermission.
                                                             (line   29)
* mysql_setpermission, host option:      mysql-setpermission.
                                                             (line   33)
* mysql_setpermission, password option:  mysql-setpermission.
                                                             (line   37)
* mysql_setpermission, port option:      mysql-setpermission.
                                                             (line   47)
* mysql_setpermission, socket option:    mysql-setpermission.
                                                             (line   51)
* mysql_setpermission, user option:      mysql-setpermission.
                                                             (line   55)
* mysql_shutdown():                      mysql-shutdown.     (line    6)
* mysql_sqlstate():                      mysql-sqlstate.     (line    6)
* mysql_ssl_set():                       mysql-ssl-set.      (line    6)
* mysql_stat():                          mysql-stat.         (line    6)
* MYSQL_STMT C type:                     c-api-prepared-statement-datatypes.
                                                             (line   24)
* mysql_stmt_affected_rows():            mysql-stmt-affected-rows.
                                                             (line    6)
* mysql_stmt_attr_get():                 mysql-stmt-attr-get.
                                                             (line    6)
* mysql_stmt_attr_set():                 mysql-stmt-attr-set.
                                                             (line    6)
* mysql_stmt_bind_param():               mysql-stmt-bind-param.
                                                             (line    6)
* mysql_stmt_bind_result():              mysql-stmt-bind-result.
                                                             (line    6)
* mysql_stmt_close():                    mysql-stmt-close.   (line    6)
* mysql_stmt_data_seek():                mysql-stmt-data-seek.
                                                             (line    6)
* mysql_stmt_errno():                    mysql-stmt-errno.   (line    6)
* mysql_stmt_error():                    mysql-stmt-error.   (line    6)
* mysql_stmt_execute():                  mysql-stmt-execute. (line    6)
* mysql_stmt_fetch():                    mysql-stmt-fetch.   (line    6)
* mysql_stmt_fetch_column():             mysql-stmt-fetch-column.
                                                             (line    6)
* mysql_stmt_field_count():              mysql-stmt-field-count.
                                                             (line    6)
* mysql_stmt_free_result():              mysql-stmt-free-result.
                                                             (line    6)
* mysql_stmt_init():                     mysql-stmt-init.    (line    6)
* mysql_stmt_insert_id():                mysql-stmt-insert-id.
                                                             (line    6)
* mysql_stmt_next_result():              mysql-stmt-next-result.
                                                             (line    6)
* mysql_stmt_num_rows():                 mysql-stmt-num-rows.
                                                             (line    6)
* mysql_stmt_param_count():              mysql-stmt-param-count.
                                                             (line    6)
* mysql_stmt_param_metadata():           mysql-stmt-param-metadata.
                                                             (line    6)
* mysql_stmt_prepare():                  mysql-stmt-prepare. (line    6)
* mysql_stmt_reset():                    mysql-stmt-reset.   (line    6)
* mysql_stmt_result_metadata:            mysql-stmt-result-metadata.
                                                             (line    6)
* mysql_stmt_row_seek():                 mysql-stmt-row-seek.
                                                             (line    6)
* mysql_stmt_row_tell():                 mysql-stmt-row-tell.
                                                             (line    6)
* mysql_stmt_send_long_data():           mysql-stmt-send-long-data.
                                                             (line    6)
* mysql_stmt_sqlstate():                 mysql-stmt-sqlstate.
                                                             (line    6)
* mysql_stmt_store_result():             mysql-stmt-store-result.
                                                             (line    6)
* mysql_store_result() <1>:              c-api-problems.     (line   13)
* mysql_store_result():                  mysql-store-result. (line    6)
* MYSQL_TCP_PORT environment variable <1>: multiple-server-clients.
                                                             (line   27)
* MYSQL_TCP_PORT environment variable <2>: multiple-unix-servers.
                                                             (line   59)
* MYSQL_TCP_PORT environment variable <3>: programs-overview.
                                                             (line  291)
* MYSQL_TCP_PORT environment variable:   environment-variables.
                                                             (line   18)
* mysql_thread_end():                    mysql-thread-end.   (line    6)
* mysql_thread_id():                     mysql-thread-id.    (line    6)
* mysql_thread_init():                   mysql-thread-init.  (line    6)
* mysql_thread_safe():                   mysql-thread-safe.  (line    6)
* MYSQL_TIME C type:                     c-api-prepared-statement-datatypes.
                                                             (line  229)
* mysql_tzinfo_to_sql <1>:               mysql-tzinfo-to-sql.
                                                             (line    6)
* mysql_tzinfo_to_sql:                   programs-overview.  (line   95)
* MYSQL_UNIX_PORT environment variable <1>: multiple-server-clients.
                                                             (line   27)
* MYSQL_UNIX_PORT environment variable <2>: multiple-unix-servers.
                                                             (line   59)
* MYSQL_UNIX_PORT environment variable <3>: programs-overview.
                                                             (line  291)
* MYSQL_UNIX_PORT environment variable <4>: environment-variables.
                                                             (line   18)
* MYSQL_UNIX_PORT environment variable:  mysql-install-db-problems.
                                                             (line   83)
* mysql_upgrade <1>:                     access-denied.      (line   90)
* mysql_upgrade <2>:                     mysql-upgrade.      (line    6)
* mysql_upgrade:                         programs-overview.  (line  102)
* mysql_upgrade, basedir option:         mysql-upgrade.      (line   90)
* mysql_upgrade, datadir option:         mysql-upgrade.      (line   94)
* mysql_upgrade, debug-check option:     mysql-upgrade.      (line   98)
* mysql_upgrade, debug-info option:      mysql-upgrade.      (line  102)
* mysql_upgrade, force option:           mysql-upgrade.      (line  107)
* mysql_upgrade, help option:            mysql-upgrade.      (line   86)
* mysql_upgrade, mysql_upgrade_info file: mysql-upgrade.     (line   24)
* mysql_upgrade, tmpdir option:          mysql-upgrade.      (line  114)
* mysql_upgrade, user option:            mysql-upgrade.      (line  119)
* mysql_upgrade, verbose option:         mysql-upgrade.      (line  124)
* mysql_upgrade_info file, mysql_upgrade: mysql-upgrade.     (line   24)
* mysql_use_result():                    mysql-use-result.   (line    6)
* mysql_waitpid <1>:                     mysql-waitpid.      (line    6)
* mysql_waitpid:                         programs-overview.  (line  221)
* mysql_waitpid, help option:            mysql-waitpid.      (line   27)
* mysql_waitpid, verbose option:         mysql-waitpid.      (line   31)
* mysql_waitpid, version option:         mysql-waitpid.      (line   36)
* mysql_warning_count():                 mysql-warning-count.
                                                             (line    6)
* mysql_zap <1>:                         mysql-zap.          (line    6)
* mysql_zap:                             programs-overview.  (line  226)
* mysqlaccess <1>:                       mysqlaccess.        (line    6)
* mysqlaccess:                           programs-overview.  (line  177)
* mysqlaccess, brief option:             mysqlaccess.        (line   64)
* mysqlaccess, commit option:            mysqlaccess.        (line   68)
* mysqlaccess, copy option:              mysqlaccess.        (line   75)
* mysqlaccess, db option:                mysqlaccess.        (line   79)
* mysqlaccess, debug option:             mysqlaccess.        (line   83)
* mysqlaccess, help option:              mysqlaccess.        (line   60)
* mysqlaccess, host option:              mysqlaccess.        (line   87)
* mysqlaccess, howto option:             mysqlaccess.        (line   91)
* mysqlaccess, old_server option:        mysqlaccess.        (line   96)
* mysqlaccess, password option:          mysqlaccess.        (line  101)
* mysqlaccess, plan option:              mysqlaccess.        (line  110)
* mysqlaccess, preview option:           mysqlaccess.        (line  114)
* mysqlaccess, relnotes option:          mysqlaccess.        (line  119)
* mysqlaccess, rhost option:             mysqlaccess.        (line  123)
* mysqlaccess, rollback option:          mysqlaccess.        (line  127)
* mysqlaccess, spassword option:         mysqlaccess.        (line  131)
* mysqlaccess, superuser option:         mysqlaccess.        (line  141)
* mysqlaccess, table option:             mysqlaccess.        (line  145)
* mysqlaccess, user option:              mysqlaccess.        (line  149)
* mysqlaccess, version option:           mysqlaccess.        (line  153)
* mysqladmin <1>:                        kill.               (line    6)
* mysqladmin <2>:                        flush.              (line    6)
* mysqladmin <3>:                        show-variables.     (line    9)
* mysqladmin <4>:                        show-status.        (line    9)
* mysqladmin <5>:                        drop-database.      (line   47)
* mysqladmin <6>:                        create-database.    (line   42)
* mysqladmin <7>:                        mysqladmin.         (line    6)
* mysqladmin:                            programs-overview.  (line  116)
* mysqladmin command options:            mysqladmin.         (line  232)
* mysqladmin option, mysqld_multi:       mysqld-multi.       (line   94)
* mysqladmin, character-sets-dir option: mysqladmin.         (line  306)
* mysqladmin, compress option:           mysqladmin.         (line  311)
* mysqladmin, count option:              mysqladmin.         (line  316)
* mysqladmin, debug option:              mysqladmin.         (line  321)
* mysqladmin, debug-check option:        mysqladmin.         (line  327)
* mysqladmin, debug-info option:         mysqladmin.         (line  331)
* mysqladmin, default-character-set option: mysqladmin.      (line  336)
* mysqladmin, force option:              mysqladmin.         (line  341)
* mysqladmin, help option:               mysqladmin.         (line  302)
* mysqladmin, host option:               mysqladmin.         (line  346)
* mysqladmin, no-beep option:            mysqladmin.         (line  350)
* mysqladmin, password option:           mysqladmin.         (line  355)
* mysqladmin, pipe option:               mysqladmin.         (line  366)
* mysqladmin, port option:               mysqladmin.         (line  372)
* mysqladmin, protocol option:           mysqladmin.         (line  376)
* mysqladmin, relative option:           mysqladmin.         (line  383)
* mysqladmin, silent option:             mysqladmin.         (line  389)
* mysqladmin, sleep option:              mysqladmin.         (line  393)
* mysqladmin, socket option:             mysqladmin.         (line  400)
* mysqladmin, SSL options:               mysqladmin.         (line  405)
* mysqladmin, user option:               mysqladmin.         (line  411)
* mysqladmin, verbose option:            mysqladmin.         (line  415)
* mysqladmin, version option:            mysqladmin.         (line  419)
* mysqladmin, vertical option:           mysqladmin.         (line  423)
* mysqladmin, wait option:               mysqladmin.         (line  428)
* mysqlbackup:                           mysqlbackup.        (line    6)
* mysqlbackup, all option:               mysqlbackup.        (line   77)
* mysqlbackup, catalog-details option:   mysqlbackup.        (line   81)
* mysqlbackup, catalog-summary option:   mysqlbackup.        (line   85)
* mysqlbackup, data-chunks option:       mysqlbackup.        (line   89)
* mysqlbackup, data-totals option:       mysqlbackup.        (line   94)
* mysqlbackup, debug option:             mysqlbackup.        (line   99)
* mysqlbackup, exact option:             mysqlbackup.        (line  105)
* mysqlbackup, help option:              mysqlbackup.        (line   73)
* mysqlbackup, image-order option:       mysqlbackup.        (line  110)
* mysqlbackup, metadata-extra option:    mysqlbackup.        (line  115)
* mysqlbackup, metadata-statements option: mysqlbackup.      (line  119)
* mysqlbackup, open_files_limit option:  mysqlbackup.        (line  124)
* mysqlbackup, search option:            mysqlbackup.        (line  128)
* mysqlbackup, snapshots option:         mysqlbackup.        (line  137)
* mysqlbackup, summary option:           mysqlbackup.        (line  141)
* mysqlbackup, verbose option:           mysqlbackup.        (line  145)
* mysqlbackup, version option:           mysqlbackup.        (line  150)
* mysqlbinlog <1>:                       mysqlbinlog.        (line   11)
* mysqlbinlog:                           programs-overview.  (line  182)
* mysqlbinlog, base64-output option:     mysqlbinlog.        (line  128)
* mysqlbinlog, character-sets-dir option: mysqlbinlog.       (line  176)
* mysqlbinlog, database option:          mysqlbinlog.        (line  181)
* mysqlbinlog, debug option:             mysqlbinlog.        (line  193)
* mysqlbinlog, debug-check option:       mysqlbinlog.        (line  199)
* mysqlbinlog, debug-info option:        mysqlbinlog.        (line  203)
* mysqlbinlog, disable-log-bin option:   mysqlbinlog.        (line  208)
* mysqlbinlog, force-read option:        mysqlbinlog.        (line  222)
* mysqlbinlog, help option:              mysqlbinlog.        (line  124)
* mysqlbinlog, hexdump option:           mysqlbinlog.        (line  229)
* mysqlbinlog, host option:              mysqlbinlog.        (line  235)
* mysqlbinlog, local-load option:        mysqlbinlog.        (line  239)
* mysqlbinlog, offset option:            mysqlbinlog.        (line  244)
* mysqlbinlog, password option:          mysqlbinlog.        (line  248)
* mysqlbinlog, port option:              mysqlbinlog.        (line  259)
* mysqlbinlog, position option:          mysqlbinlog.        (line  263)
* mysqlbinlog, protocol option:          mysqlbinlog.        (line  267)
* mysqlbinlog, read-from-remote-server option: mysqlbinlog.  (line  274)
* mysqlbinlog, result-file option:       mysqlbinlog.        (line  285)
* mysqlbinlog, server-id option:         mysqlbinlog.        (line  289)
* mysqlbinlog, set-charset option:       mysqlbinlog.        (line  294)
* mysqlbinlog, short-form option:        mysqlbinlog.        (line  299)
* mysqlbinlog, socket option:            mysqlbinlog.        (line  304)
* mysqlbinlog, start-datetime option:    mysqlbinlog.        (line  309)
* mysqlbinlog, start-position option:    mysqlbinlog.        (line  323)
* mysqlbinlog, stop-datetime option:     mysqlbinlog.        (line  329)
* mysqlbinlog, stop-position option:     mysqlbinlog.        (line  336)
* mysqlbinlog, to-last-log option:       mysqlbinlog.        (line  342)
* mysqlbinlog, user option:              mysqlbinlog.        (line  350)
* mysqlbinlog, verbose option:           mysqlbinlog.        (line  354)
* mysqlbinlog, version option:           mysqlbinlog.        (line  365)
* mysqlbinlog, write-binlog option:      mysqlbinlog.        (line  369)
* mysqlbug:                              mysqlbug.           (line    6)
* mysqlbug script:                       bug-reports.        (line  334)
* mysqlcheck <1>:                        mysqlcheck.         (line    6)
* mysqlcheck:                            programs-overview.  (line  124)
* mysqlcheck, all-databases option:      mysqlcheck.         (line  167)
* mysqlcheck, all-in-1 option:           mysqlcheck.         (line  173)
* mysqlcheck, analyze option:            mysqlcheck.         (line  179)
* mysqlcheck, auto-repair option:        mysqlcheck.         (line  189)
* mysqlcheck, character-sets-dir option: mysqlcheck.         (line  194)
* mysqlcheck, check option:              mysqlcheck.         (line  199)
* mysqlcheck, check-only-changed option: mysqlcheck.         (line  203)
* mysqlcheck, check-upgrade option:      mysqlcheck.         (line  208)
* mysqlcheck, compress option:           mysqlcheck.         (line  215)
* mysqlcheck, databases option:          mysqlcheck.         (line  220)
* mysqlcheck, debug option:              mysqlcheck.         (line  228)
* mysqlcheck, debug-check option:        mysqlcheck.         (line  233)
* mysqlcheck, debug-info option:         mysqlcheck.         (line  237)
* mysqlcheck, default-character-set option: mysqlcheck.      (line  242)
* mysqlcheck, extended option:           mysqlcheck.         (line  247)
* mysqlcheck, fast option:               mysqlcheck.         (line  256)
* mysqlcheck, fix-db-names option:       mysqlcheck.         (line  260)
* mysqlcheck, fix-table-names option:    mysqlcheck.         (line  265)
* mysqlcheck, force option:              mysqlcheck.         (line  271)
* mysqlcheck, help option:               mysqlcheck.         (line  163)
* mysqlcheck, host option:               mysqlcheck.         (line  275)
* mysqlcheck, medium-check option:       mysqlcheck.         (line  279)
* mysqlcheck, optimize option:           mysqlcheck.         (line  285)
* mysqlcheck, password option:           mysqlcheck.         (line  289)
* mysqlcheck, pipe option:               mysqlcheck.         (line  300)
* mysqlcheck, port option:               mysqlcheck.         (line  306)
* mysqlcheck, protocol option:           mysqlcheck.         (line  310)
* mysqlcheck, quick option:              mysqlcheck.         (line  317)
* mysqlcheck, repair option:             mysqlcheck.         (line  326)
* mysqlcheck, silent option:             mysqlcheck.         (line  331)
* mysqlcheck, socket option:             mysqlcheck.         (line  335)
* mysqlcheck, SSL options:               mysqlcheck.         (line  340)
* mysqlcheck, tables option:             mysqlcheck.         (line  346)
* mysqlcheck, use-frm option:            mysqlcheck.         (line  351)
* mysqlcheck, user option:               mysqlcheck.         (line  357)
* mysqlcheck, verbose option:            mysqlcheck.         (line  361)
* mysqlcheck, version option:            mysqlcheck.         (line  366)
* mysqlclient library:                   connectors-apis.    (line   26)
* mysqld:                                programs-overview.  (line   36)
* mysqld library:                        connectors-apis.    (line   26)
* mysqld option, mysqld_multi:           mysqld-multi.       (line   99)
* mysqld option, mysqld_safe:            mysqld-safe.        (line  151)
* mysqld options:                        server-parameters.  (line   11)
* mysqld server, buffer sizes:           server-parameters.  (line    6)
* mysqld, abort-slave-event-count option: replication-options-slave.
                                                             (line  668)
* mysqld, allow-suspicious-udfs option <1>: privileges-options.
                                                             (line   37)
* mysqld, allow-suspicious-udfs option:  server-options.     (line   60)
* mysqld, ansi option:                   server-options.     (line   76)
* mysqld, basedir option:                server-options.     (line   86)
* mysqld, big-tables option:             server-options.     (line  102)
* mysqld, bind-address option:           server-options.     (line  122)
* mysqld, binlog-do-db option:           replication-options-binary-log.
                                                             (line   87)
* mysqld, binlog-format option:          server-options.     (line  139)
* mysqld, binlog-ignore-db option:       replication-options-binary-log.
                                                             (line  186)
* mysqld, binlog-row-event-max-size option: replication-options-binary-log.
                                                             (line   23)
* mysqld, bootstrap option:              server-options.     (line  159)
* mysqld, character-set-client-handshake option: server-options.
                                                             (line  188)
* mysqld, character-set-filesystem option: server-options.   (line  202)
* mysqld, character-set-server option:   server-options.     (line  218)
* mysqld, character-sets-dir option:     server-options.     (line  172)
* mysqld, chroot option:                 server-options.     (line  236)
* mysqld, collation-server option:       server-options.     (line  250)
* mysqld, command options:               server-options.     (line    6)
* mysqld, console option:                server-options.     (line  266)
* mysqld, core-file option:              server-options.     (line  279)
* mysqld, datadir option:                server-options.     (line  305)
* mysqld, debug option:                  server-options.     (line  320)
* mysqld, debug-sync-timeout option:     server-options.     (line  349)
* mysqld, default-character-set option:  server-options.     (line  374)
* mysqld, default-collation option:      server-options.     (line  387)
* mysqld, default-storage-engine option: server-options.     (line  402)
* mysqld, default-table-type option:     server-options.     (line  411)
* mysqld, default-time-zone option:      server-options.     (line  424)
* mysqld, delay-key-write option <1>:    myisam-start.       (line   38)
* mysqld, delay-key-write option:        server-options.     (line  437)
* mysqld, des-key-file option:           server-options.     (line  466)
* mysqld, disconnect-slave-event-count option: replication-options-slave.
                                                             (line  691)
* mysqld, enable-named-pipe option:      server-options.     (line  475)
* mysqld, enable-pstack option:          server-options.     (line  480)
* mysqld, event-scheduler option:        server-options.     (line  521)
* mysqld, exit-info option:              server-options.     (line  541)
* mysqld, external-locking option:       server-options.     (line  553)
* mysqld, flush option:                  server-options.     (line  575)
* mysqld, gdb option:                    server-options.     (line  592)
* mysqld, general-log option:            server-options.     (line  606)
* mysqld, help option:                   server-options.     (line   51)
* mysqld, init-file option:              server-options.     (line  625)
* mysqld, innodb option:                 innodb-parameters.  (line  117)
* mysqld, innodb_status_file option:     innodb-parameters.  (line  122)
* mysqld, language option:               server-options.     (line  648)
* mysqld, large-pages option:            server-options.     (line  667)
* mysqld, local-infile option:           privileges-options. (line   46)
* mysqld, log option:                    server-options.     (line  695)
* mysqld, log-backup-output option:      server-options.     (line  722)
* mysqld, log-bin option:                replication-options-binary-log.
                                                             (line   44)
* mysqld, log-bin-index option:          replication-options-binary-log.
                                                             (line   68)
* mysqld, log-bin-trust-function-creators option: replication-options-binary-log.
                                                             (line  246)
* mysqld, log-error option:              server-options.     (line  761)
* mysqld, log-isam option:               server-options.     (line  779)
* mysqld, log-long-format option:        server-options.     (line  790)
* mysqld, log-output option:             server-options.     (line  805)
* mysqld, log-queries-not-using-indexes option: server-options.
                                                             (line  841)
* mysqld, log-short-format option:       server-options.     (line  862)
* mysqld, log-slave-updates option:      replication-options-slave.
                                                             (line   90)
* mysqld, log-slow-admin-statements option: server-options.  (line  875)
* mysqld, log-slow-queries option:       server-options.     (line  888)
* mysqld, log-slow-slave-statements option: replication-options-slave.
                                                             (line  110)
* mysqld, log-tc option:                 server-options.     (line  918)
* mysqld, log-tc-size option:            server-options.     (line  933)
* mysqld, log-warnings option <1>:       replication-options-slave.
                                                             (line  126)
* mysqld, log-warnings option:           server-options.     (line  952)
* mysqld, low-priority-updates option:   server-options.     (line  985)
* mysqld, master-info-file option:       replication-options-slave.
                                                             (line  140)
* mysqld, master-retry-count option:     replication-options-slave.
                                                             (line  146)
* mysqld, max-binlog-dump-events option: replication-options-binary-log.
                                                             (line  272)
* mysqld, max-relay-log-size option:     replication-options-slave.
                                                             (line  160)
* mysqld, memlock option:                server-options.     (line 1033)
* mysqld, min-examined-row-limit option: server-options.     (line 1008)
* mysqld, myisam-block-size option:      server-options.     (line 1074)
* mysqld, myisam-recover option <1>:     myisam-start.       (line   34)
* mysqld, myisam-recover option:         server-options.     (line 1086)
* mysqld, MySQL server <1>:              mysqld-server.      (line   19)
* mysqld, MySQL server:                  mysqld.             (line    6)
* mysqld, old-passwords option <1>:      privileges-options. (line   52)
* mysqld, old-passwords option:          server-options.     (line 1132)
* mysqld, old-style-user-limits option:  server-options.     (line 1150)
* mysqld, one-thread option:             server-options.     (line 1164)
* mysqld, open-files-limit option:       server-options.     (line 1178)
* mysqld, pid-file option:               server-options.     (line 1206)
* mysqld, plugin-load option:            server-options.     (line 1223)
* mysqld, port option:                   server-options.     (line 1259)
* mysqld, port-open-timeout option:      server-options.     (line 1277)
* mysqld, read-only option:              replication-options-slave.
                                                             (line  166)
* mysqld, relay-log option:              replication-options-slave.
                                                             (line  174)
* mysqld, relay-log-index option:        replication-options-slave.
                                                             (line  206)
* mysqld, relay-log-info-file option:    replication-options-slave.
                                                             (line  227)
* mysqld, relay-log-purge option:        replication-options-slave.
                                                             (line  233)
* mysqld, relay-log-recovery option:     replication-options-slave.
                                                             (line  240)
* mysqld, relay-log-space-limit option:  replication-options-slave.
                                                             (line  249)
* mysqld, replicate-do-db option:        replication-options-slave.
                                                             (line  270)
* mysqld, replicate-do-table option:     replication-options-slave.
                                                             (line  430)
* mysqld, replicate-ignore-db option:    replication-options-slave.
                                                             (line  373)
* mysqld, replicate-ignore-table option: replication-options-slave.
                                                             (line  437)
* mysqld, replicate-rewrite-db option:   replication-options-slave.
                                                             (line  446)
* mysqld, replicate-same-server-id option: replication-options-slave.
                                                             (line  466)
* mysqld, replicate-wild-do-table option: replication-options-slave.
                                                             (line  480)
* mysqld, replicate-wild-ignore-table option: replication-options-slave.
                                                             (line  513)
* mysqld, report-host option:            replication-options-slave.
                                                             (line  530)
* mysqld, report-password option:        replication-options-slave.
                                                             (line  542)
* mysqld, report-port option:            replication-options-slave.
                                                             (line  549)
* mysqld, report-user option:            replication-options-slave.
                                                             (line  557)
* mysqld, safe-mode option:              server-options.     (line 1292)
* mysqld, safe-show-database option <1>: privileges-options. (line   64)
* mysqld, safe-show-database option:     server-options.     (line 1301)
* mysqld, safe-user-create option <1>:   privileges-options. (line   74)
* mysqld, safe-user-create option:       server-options.     (line 1317)
* mysqld, secure-auth option <1>:        privileges-options. (line   89)
* mysqld, secure-auth option:            server-options.     (line 1339)
* mysqld, secure-backup-file-priv option <1>: privileges-options.
                                                             (line   98)
* mysqld, secure-backup-file-priv option: server-options.    (line 1356)
* mysqld, secure-file-priv option <1>:   privileges-options. (line  117)
* mysqld, secure-file-priv option:       server-options.     (line 1375)
* mysqld, server-id option:              replication-options.
                                                             (line   21)
* mysqld, shared-memory option:          server-options.     (line 1396)
* mysqld, shared-memory-base-name option: server-options.    (line 1401)
* mysqld, show-slave-auth-info option:   replication-options-slave.
                                                             (line  564)
* mysqld, skip-concurrent-insert option: server-options.     (line 1407)
* mysqld, skip-external-locking option:  server-options.     (line 1413)
* mysqld, skip-grant-tables option <1>:  privileges-options. (line  138)
* mysqld, skip-grant-tables option:      server-options.     (line 1421)
* mysqld, skip-host-cache option:        server-options.     (line 1438)
* mysqld, skip-innodb option:            server-options.     (line 1444)
* mysqld, skip-name-resolve option <1>:  privileges-options. (line  149)
* mysqld, skip-name-resolve option:      server-options.     (line 1450)
* mysqld, skip-networking option <1>:    privileges-options. (line  154)
* mysqld, skip-networking option:        server-options.     (line 1457)
* mysqld, skip-safemalloc option:        server-options.     (line 1503)
* mysqld, skip-show-database option <1>: privileges-options. (line  159)
* mysqld, skip-show-database option:     server-options.     (line 1515)
* mysqld, skip-slave-start option:       replication-options-slave.
                                                             (line  571)
* mysqld, skip-stack-trace option:       server-options.     (line 1535)
* mysqld, skip-symbolic-links option:    server-options.     (line 1481)
* mysqld, skip-thread-priority option:   server-options.     (line 1547)
* mysqld, slave-load-tmpdir option:      replication-options-slave.
                                                             (line  583)
* mysqld, slave-net-timeout option:      replication-options-slave.
                                                             (line  605)
* mysqld, slave-skip-errors option:      replication-options-slave.
                                                             (line  616)
* mysqld, slave_compressed_protocol option: replication-options-slave.
                                                             (line  577)
* mysqld, slow-query-log option:         server-options.     (line 1558)
* mysqld, socket option:                 server-options.     (line 1577)
* mysqld, sporadic-binlog-dump-fail option: replication-options-binary-log.
                                                             (line  283)
* mysqld, sql-mode option:               server-options.     (line 1597)
* mysqld, SSL options <1>:               privileges-options. (line  169)
* mysqld, SSL options:                   server-options.     (line 1465)
* mysqld, standalone option:             server-options.     (line 1471)
* mysqld, starting:                      changing-mysql-user.
                                                             (line    6)
* mysqld, symbolic-links option:         server-options.     (line 1481)
* mysqld, sysdate-is-now option:         server-options.     (line 1635)
* mysqld, tc-heuristic-recover option:   server-options.     (line 1652)
* mysqld, temp-pool option:              server-options.     (line 1665)
* mysqld, tmpdir option:                 server-options.     (line 1699)
* mysqld, transaction-isolation option:  server-options.     (line 1682)
* mysqld, user option:                   server-options.     (line 1728)
* mysqld, verbose option:                server-options.     (line 1758)
* mysqld, version option:                server-options.     (line 1762)
* mysqld-version option, mysqld_safe:    mysqld-safe.        (line  160)
* mysqld_multi <1>:                      mysqld-multi.       (line    6)
* mysqld_multi:                          programs-overview.  (line   56)
* mysqld_multi, config-file option:      mysqld-multi.       (line   80)
* mysqld_multi, defaults-extra-file option: mysqld-multi.    (line   66)
* mysqld_multi, defaults-file option:    mysqld-multi.       (line   64)
* mysqld_multi, example option:          mysqld-multi.       (line   85)
* mysqld_multi, help option:             mysqld-multi.       (line   76)
* mysqld_multi, log option:              mysqld-multi.       (line   89)
* mysqld_multi, mysqladmin option:       mysqld-multi.       (line   94)
* mysqld_multi, mysqld option:           mysqld-multi.       (line   99)
* mysqld_multi, no-defaults option:      mysqld-multi.       (line   62)
* mysqld_multi, no-log option:           mysqld-multi.       (line  115)
* mysqld_multi, password option:         mysqld-multi.       (line  120)
* mysqld_multi, silent option:           mysqld-multi.       (line  126)
* mysqld_multi, tcp-ip option:           mysqld-multi.       (line  130)
* mysqld_multi, user option:             mysqld-multi.       (line  138)
* mysqld_multi, verbose option:          mysqld-multi.       (line  143)
* mysqld_multi, version option:          mysqld-multi.       (line  147)
* mysqld_safe <1>:                       mysqld-safe.        (line    6)
* mysqld_safe:                           programs-overview.  (line   43)
* mysqld_safe, autoclose option:         mysqld-safe.        (line  103)
* mysqld_safe, basedir option:           mysqld-safe.        (line  115)
* mysqld_safe, core-file-size option:    mysqld-safe.        (line  119)
* mysqld_safe, datadir option:           mysqld-safe.        (line  124)
* mysqld_safe, defaults-extra-file option: mysqld-safe.      (line  128)
* mysqld_safe, defaults-file option:     mysqld-safe.        (line  135)
* mysqld_safe, help option:              mysqld-safe.        (line   99)
* mysqld_safe, ledir option:             mysqld-safe.        (line  141)
* mysqld_safe, log-error option:         mysqld-safe.        (line  147)
* mysqld_safe, mysqld option:            mysqld-safe.        (line  151)
* mysqld_safe, mysqld-version option:    mysqld-safe.        (line  160)
* mysqld_safe, nice option:              mysqld-safe.        (line  171)
* mysqld_safe, no-defaults option:       mysqld-safe.        (line  176)
* mysqld_safe, open-files-limit option:  mysqld-safe.        (line  181)
* mysqld_safe, pid-file option:          mysqld-safe.        (line  188)
* mysqld_safe, port option:              mysqld-safe.        (line  192)
* mysqld_safe, skip-kill-mysqld option:  mysqld-safe.        (line  198)
* mysqld_safe, skip-syslog option:       mysqld-safe.        (line  208)
* mysqld_safe, socket option:            mysqld-safe.        (line  203)
* mysqld_safe, syslog option:            mysqld-safe.        (line  208)
* mysqld_safe, syslog-tag option:        mysqld-safe.        (line  214)
* mysqld_safe, timezone option:          mysqld-safe.        (line  222)
* mysqld_safe, user option:              mysqld-safe.        (line  228)
* mysqldump <1>:                         mysqldump.          (line    6)
* mysqldump <2>:                         programs-overview.  (line  129)
* mysqldump:                             copying-databases.  (line   45)
* mysqldump, add-drop-database option:   mysqldump.          (line  262)
* mysqldump, add-drop-table option:      mysqldump.          (line  267)
* mysqldump, add-locks option:           mysqldump.          (line  272)
* mysqldump, all-databases option:       mysqldump.          (line  279)
* mysqldump, allow-keywords option:      mysqldump.          (line  285)
* mysqldump, apply-slave-statements option: mysqldump.       (line  290)
* mysqldump, character-sets-dir option:  mysqldump.          (line  298)
* mysqldump, comments option:            mysqldump.          (line  303)
* mysqldump, compact option:             mysqldump.          (line  310)
* mysqldump, compatible option:          mysqldump.          (line  316)
* mysqldump, complete-insert option:     mysqldump.          (line  336)
* mysqldump, compress option:            mysqldump.          (line  341)
* mysqldump, create-options option:      mysqldump.          (line  346)
* mysqldump, databases option:           mysqldump.          (line  351)
* mysqldump, debug option:               mysqldump.          (line  360)
* mysqldump, debug-check option:         mysqldump.          (line  366)
* mysqldump, debug-info option:          mysqldump.          (line  370)
* mysqldump, default-character-set option: mysqldump.        (line  375)
* mysqldump, delayed-insert option:      mysqldump.          (line  385)
* mysqldump, delete-master-logs option:  mysqldump.          (line  390)
* mysqldump, disable-keys option:        mysqldump.          (line  396)
* mysqldump, dump-date option:           mysqldump.          (line  405)
* mysqldump, dump-slave option:          mysqldump.          (line  416)
* mysqldump, events option:              mysqldump.          (line  436)
* mysqldump, extended-insert option:     mysqldump.          (line  440)
* mysqldump, fields-enclosed-by option <1>: mysqlimport.     (line  156)
* mysqldump, fields-enclosed-by option:  mysqldump.          (line  448)
* mysqldump, fields-escaped-by option <1>: mysqlimport.      (line  160)
* mysqldump, fields-escaped-by option:   mysqldump.          (line  452)
* mysqldump, fields-optionally-enclosed-by option <1>: mysqlimport.
                                                             (line  158)
* mysqldump, fields-optionally-enclosed-by option: mysqldump.
                                                             (line  450)
* mysqldump, fields-terminated-by option <1>: mysqlimport.   (line  154)
* mysqldump, fields-terminated-by option: mysqldump.         (line  446)
* mysqldump, first-slave option:         mysqldump.          (line  458)
* mysqldump, flush-logs option:          mysqldump.          (line  462)
* mysqldump, flush-privileges option:    mysqldump.          (line  474)
* mysqldump, force option:               mysqldump.          (line  481)
* mysqldump, help option:                mysqldump.          (line  258)
* mysqldump, hex-blob option:            mysqldump.          (line  499)
* mysqldump, host option:                mysqldump.          (line  494)
* mysqldump, ignore-table option:        mysqldump.          (line  514)
* mysqldump, include-master-host-port option: mysqldump.     (line  506)
* mysqldump, insert-ignore option:       mysqldump.          (line  521)
* mysqldump, lines-terminated-by option <1>: mysqlimport.    (line  184)
* mysqldump, lines-terminated-by option: mysqldump.          (line  525)
* mysqldump, lock-all-tables option:     mysqldump.          (line  531)
* mysqldump, lock-tables option:         mysqldump.          (line  538)
* mysqldump, log-error option:           mysqldump.          (line  552)
* mysqldump, master-data option:         mysqldump.          (line  556)
* mysqldump, no-autocommit option:       mysqldump.          (line  586)
* mysqldump, no-create-db option:        mysqldump.          (line  592)
* mysqldump, no-create-info option:      mysqldump.          (line  598)
* mysqldump, no-data option:             mysqldump.          (line  603)
* mysqldump, opt option:                 mysqldump.          (line  609)
* mysqldump, order-by-primary option:    mysqldump.          (line  623)
* mysqldump, password option:            mysqldump.          (line  630)
* mysqldump, pipe option:                mysqldump.          (line  641)
* mysqldump, port option:                mysqldump.          (line  647)
* mysqldump, problems <1>:               view-restrictions.  (line   82)
* mysqldump, problems:                   mysqldump.          (line  976)
* mysqldump, protocol option:            mysqldump.          (line  651)
* mysqldump, quick option:               mysqldump.          (line  658)
* mysqldump, quote-names option:         mysqldump.          (line  665)
* mysqldump, replace option:             mysqldump.          (line  674)
* mysqldump, result-file option:         mysqldump.          (line  679)
* mysqldump, routines option:            mysqldump.          (line  687)
* mysqldump, set-charset option:         mysqldump.          (line  705)
* mysqldump, single-transaction option:  mysqldump.          (line  711)
* mysqldump, skip-comments option:       mysqldump.          (line  741)
* mysqldump, skip-opt option:            mysqldump.          (line  745)
* mysqldump, socket option:              mysqldump.          (line  749)
* mysqldump, SSL options:                mysqldump.          (line  754)
* mysqldump, tab option:                 mysqldump.          (line  760)
* mysqldump, tables option:              mysqldump.          (line  787)
* mysqldump, triggers option:            mysqldump.          (line  793)
* mysqldump, tz-utc option:              mysqldump.          (line  798)
* mysqldump, user option:                mysqldump.          (line  810)
* mysqldump, verbose option:             mysqldump.          (line  814)
* mysqldump, version option:             mysqldump.          (line  818)
* mysqldump, views <1>:                  view-restrictions.  (line   82)
* mysqldump, views:                      mysqldump.          (line  976)
* mysqldump, where option:               mysqldump.          (line  822)
* mysqldump, workarounds <1>:            view-restrictions.  (line   82)
* mysqldump, workarounds:                mysqldump.          (line  976)
* mysqldump, xml option:                 mysqldump.          (line  834)
* mysqldumpslow <1>:                     mysqldumpslow.      (line    6)
* mysqldumpslow:                         programs-overview.  (line  188)
* mysqldumpslow, debug option:           mysqldumpslow.      (line   52)
* mysqldumpslow, help option:            mysqldumpslow.      (line   44)
* mysqldumpslow, verbose option:         mysqldumpslow.      (line   99)
* mysqlhotcopy <1>:                      mysqlhotcopy.       (line    6)
* mysqlhotcopy:                          programs-overview.  (line  193)
* mysqlhotcopy, addtodest option:        mysqlhotcopy.       (line   73)
* mysqlhotcopy, allowold option:         mysqlhotcopy.       (line   78)
* mysqlhotcopy, checkpoint option:       mysqlhotcopy.       (line   83)
* mysqlhotcopy, chroot option:           mysqlhotcopy.       (line   88)
* mysqlhotcopy, debug option:            mysqlhotcopy.       (line   94)
* mysqlhotcopy, dryrun option:           mysqlhotcopy.       (line   98)
* mysqlhotcopy, flushlog option:         mysqlhotcopy.       (line  102)
* mysqlhotcopy, help option:             mysqlhotcopy.       (line   69)
* mysqlhotcopy, host option:             mysqlhotcopy.       (line  106)
* mysqlhotcopy, keepold option:          mysqlhotcopy.       (line  112)
* mysqlhotcopy, method option:           mysqlhotcopy.       (line  116)
* mysqlhotcopy, noindices option:        mysqlhotcopy.       (line  120)
* mysqlhotcopy, password option:         mysqlhotcopy.       (line  126)
* mysqlhotcopy, port option:             mysqlhotcopy.       (line  136)
* mysqlhotcopy, quiet option:            mysqlhotcopy.       (line  140)
* mysqlhotcopy, record_log_pos option:   mysqlhotcopy.       (line  144)
* mysqlhotcopy, regexp option:           mysqlhotcopy.       (line  149)
* mysqlhotcopy, resetmaster option:      mysqlhotcopy.       (line  154)
* mysqlhotcopy, resetslave option:       mysqlhotcopy.       (line  158)
* mysqlhotcopy, socket option:           mysqlhotcopy.       (line  162)
* mysqlhotcopy, suffix option:           mysqlhotcopy.       (line  166)
* mysqlhotcopy, tmpdir option:           mysqlhotcopy.       (line  170)
* mysqlhotcopy, user option:             mysqlhotcopy.       (line  174)
* mysqlimport <1>:                       load-data.          (line   64)
* mysqlimport <2>:                       mysqlimport.        (line    6)
* mysqlimport <3>:                       programs-overview.  (line  134)
* mysqlimport:                           copying-databases.  (line   45)
* mysqlimport, character-sets-dir option: mysqlimport.       (line  115)
* mysqlimport, columns option:           mysqlimport.        (line  120)
* mysqlimport, compress option:          mysqlimport.        (line  126)
* mysqlimport, debug option:             mysqlimport.        (line  131)
* mysqlimport, debug-check option:       mysqlimport.        (line  136)
* mysqlimport, debug-info option:        mysqlimport.        (line  140)
* mysqlimport, default-character-set option: mysqlimport.    (line  145)
* mysqlimport, delete option:            mysqlimport.        (line  150)
* mysqlimport, force option:             mysqlimport.        (line  165)
* mysqlimport, help option:              mysqlimport.        (line  111)
* mysqlimport, host option:              mysqlimport.        (line  171)
* mysqlimport, ignore option:            mysqlimport.        (line  176)
* mysqlimport, ignore-lines option:      mysqlimport.        (line  180)
* mysqlimport, local option:             mysqlimport.        (line  193)
* mysqlimport, lock-tables option:       mysqlimport.        (line  204)
* mysqlimport, low-priority option:      mysqlimport.        (line  209)
* mysqlimport, password option:          mysqlimport.        (line  215)
* mysqlimport, pipe option:              mysqlimport.        (line  226)
* mysqlimport, port option:              mysqlimport.        (line  232)
* mysqlimport, protocol option:          mysqlimport.        (line  236)
* mysqlimport, replace option:           mysqlimport.        (line  243)
* mysqlimport, silent option:            mysqlimport.        (line  253)
* mysqlimport, socket option:            mysqlimport.        (line  257)
* mysqlimport, SSL options:              mysqlimport.        (line  262)
* mysqlimport, use-threads option:       mysqlimport.        (line  272)
* mysqlimport, user option:              mysqlimport.        (line  268)
* mysqlimport, verbose option:           mysqlimport.        (line  276)
* mysqlimport, version option:           mysqlimport.        (line  280)
* mysqlshow <1>:                         mysqlshow.          (line    6)
* mysqlshow:                             programs-overview.  (line  139)
* mysqlshow, character-sets-dir option:  mysqlshow.          (line  105)
* mysqlshow, compress option:            mysqlshow.          (line  110)
* mysqlshow, count option:               mysqlshow.          (line  115)
* mysqlshow, debug option:               mysqlshow.          (line  120)
* mysqlshow, debug-check option:         mysqlshow.          (line  125)
* mysqlshow, debug-info option:          mysqlshow.          (line  129)
* mysqlshow, default-character-set option: mysqlshow.        (line  134)
* mysqlshow, help option:                mysqlshow.          (line  101)
* mysqlshow, host option:                mysqlshow.          (line  139)
* mysqlshow, keys option:                mysqlshow.          (line  143)
* mysqlshow, password option:            mysqlshow.          (line  147)
* mysqlshow, pipe option:                mysqlshow.          (line  158)
* mysqlshow, port option:                mysqlshow.          (line  164)
* mysqlshow, protocol option:            mysqlshow.          (line  168)
* mysqlshow, show-table-type option:     mysqlshow.          (line  175)
* mysqlshow, socket option:              mysqlshow.          (line  180)
* mysqlshow, SSL options:                mysqlshow.          (line  185)
* mysqlshow, status option:              mysqlshow.          (line  191)
* mysqlshow, user option:                mysqlshow.          (line  195)
* mysqlshow, verbose option:             mysqlshow.          (line  199)
* mysqlshow, version option:             mysqlshow.          (line  205)
* mysqlslap <1>:                         mysqlslap.          (line    6)
* mysqlslap:                             programs-overview.  (line  144)
* mysqlslap, auto-generate-sql option:   mysqlslap.          (line  196)
* mysqlslap, auto-generate-sql-add-autoincrement option: mysqlslap.
                                                             (line  201)
* mysqlslap, auto-generate-sql-execute-number option: mysqlslap.
                                                             (line  205)
* mysqlslap, auto-generate-sql-guid-primary option: mysqlslap.
                                                             (line  209)
* mysqlslap, auto-generate-sql-load-type option: mysqlslap.  (line  213)
* mysqlslap, auto-generate-sql-secondary-indexes option: mysqlslap.
                                                             (line  220)
* mysqlslap, auto-generate-sql-select-columns option: mysqlslap.
                                                             (line  225)
* mysqlslap, auto-generate-sql-unique-query-number option: mysqlslap.
                                                             (line  232)
* mysqlslap, auto-generate-sql-unique-write-number option: mysqlslap.
                                                             (line  240)
* mysqlslap, auto-generate-sql-write-number option: mysqlslap.
                                                             (line  245)
* mysqlslap, burnin option:              mysqlslap.          (line  249)
* mysqlslap, commit option:              mysqlslap.          (line  254)
* mysqlslap, compress option:            mysqlslap.          (line  259)
* mysqlslap, concurrency option:         mysqlslap.          (line  264)
* mysqlslap, create option:              mysqlslap.          (line  269)
* mysqlslap, create-schema option:       mysqlslap.          (line  274)
* mysqlslap, csv option:                 mysqlslap.          (line  278)
* mysqlslap, debug option:               mysqlslap.          (line  283)
* mysqlslap, debug-check option:         mysqlslap.          (line  289)
* mysqlslap, debug-info option:          mysqlslap.          (line  293)
* mysqlslap, delayed-start option:       mysqlslap.          (line  303)
* mysqlslap, delimiter option:           mysqlslap.          (line  298)
* mysqlslap, detach option:              mysqlslap.          (line  309)
* mysqlslap, engine option:              mysqlslap.          (line  314)
* mysqlslap, help option:                mysqlslap.          (line  192)
* mysqlslap, host option:                mysqlslap.          (line  318)
* mysqlslap, ignore-sql-errors option:   mysqlslap.          (line  322)
* mysqlslap, iterations option:          mysqlslap.          (line  328)
* mysqlslap, label option:               mysqlslap.          (line  332)
* mysqlslap, number-blob-cols option:    mysqlslap.          (line  337)
* mysqlslap, number-char-cols option:    mysqlslap.          (line  345)
* mysqlslap, number-int-cols option:     mysqlslap.          (line  350)
* mysqlslap, number-of-queries option:   mysqlslap.          (line  355)
* mysqlslap, only-print option:          mysqlslap.          (line  359)
* mysqlslap, password option:            mysqlslap.          (line  364)
* mysqlslap, pipe option:                mysqlslap.          (line  377)
* mysqlslap, port option:                mysqlslap.          (line  383)
* mysqlslap, post-query option:          mysqlslap.          (line  387)
* mysqlslap, post-system option:         mysqlslap.          (line  399)
* mysqlslap, pre-query option:           mysqlslap.          (line  404)
* mysqlslap, pre-system option:          mysqlslap.          (line  410)
* mysqlslap, preserve-schema option:     mysqlslap.          (line  415)
* mysqlslap, protocol option:            mysqlslap.          (line  421)
* mysqlslap, query option:               mysqlslap.          (line  428)
* mysqlslap, set-random-seed option:     mysqlslap.          (line  433)
* mysqlslap, shared-memory-base-name option: mysqlslap.      (line  393)
* mysqlslap, silent option:              mysqlslap.          (line  437)
* mysqlslap, slave option:               mysqlslap.          (line  441)
* mysqlslap, socket option:              mysqlslap.          (line  449)
* mysqlslap, SSL options:                mysqlslap.          (line  454)
* mysqlslap, timer-length option:        mysqlslap.          (line  460)
* mysqlslap, user option:                mysqlslap.          (line  465)
* mysqlslap, verbose option:             mysqlslap.          (line  469)
* mysqlslap, version option:             mysqlslap.          (line  475)
* mysqltest, MySQL Test Suite:           mysql-test-suite.   (line    6)
* NAME_CONST():                          miscellaneous-functions.
                                                             (line  162)
* name_file option, comp_err:            comp-err.           (line   53)
* named pipes <1>:                       windows-testing.    (line    6)
* named pipes:                           windows-select-server.
                                                             (line   27)
* named-commands option, mysql:          mysql-command-options.
                                                             (line  270)
* named_pipe system variable:            server-system-variables.
                                                             (line 2928)
* names:                                 identifiers.        (line   13)
* names, case sensitivity:               identifier-case-sensitivity.
                                                             (line    6)
* names, variables:                      user-variables.     (line    6)
* naming, releases of MySQL:             choosing-version.   (line   60)
* NATIONAL CHAR data type:               string-type-overview.
                                                             (line   89)
* NATIONAL VARCHAR data type:            string-type-overview.
                                                             (line  121)
* native functions, adding:              adding-native-function.
                                                             (line    6)
* native thread support:                 which-os.           (line    6)
* NATURAL LEFT JOIN:                     join.               (line    6)
* NATURAL LEFT OUTER JOIN:               join.               (line    6)
* NATURAL RIGHT JOIN:                    join.               (line    6)
* NATURAL RIGHT OUTER JOIN:              join.               (line    6)
* NCHAR data type:                       string-type-overview.
                                                             (line   89)
* NDB storage engine, FAQ:               faqs-mysql-cluster. (line    6)
* negative values:                       number-syntax.      (line    6)
* nested queries:                        subqueries.         (line   20)
* nested-loop join algorithm:            nested-join-optimization.
                                                             (line  167)
* Nested-Loop join algorithm:            nested-loop-joins.  (line    6)
* net etiquette:                         mailing-list-use.   (line    6)
* net_buffer_length system variable:     server-system-variables.
                                                             (line 2938)
* net_buffer_length variable:            mysql-command-options.
                                                             (line  552)
* net_read_timeout system variable:      server-system-variables.
                                                             (line 2969)
* net_retry_count system variable:       server-system-variables.
                                                             (line 2993)
* net_write_timeout system variable:     server-system-variables.
                                                             (line 3018)
* netmask notation, in account names:    account-names.      (line   91)
* NetWare:                               netware-installation.
                                                             (line    6)
* new procedures, adding:                adding-procedures.  (line   11)
* new system variable:                   server-system-variables.
                                                             (line 3037)
* new users, adding <1>:                 quick-install.      (line  167)
* new users, adding:                     installing-binary.  (line  168)
* newline (\n) <1>:                      load-data.          (line  426)
* newline (\n):                          string-syntax.      (line   59)
* next-key lock, InnoDB <1>:             innodb-next-key-locking.
                                                             (line    6)
* next-key lock, InnoDB <2>:             innodb-record-level-locks.
                                                             (line    6)
* next-key lock, InnoDB <3>:             innodb-transaction-model.
                                                             (line   64)
* next-key lock, InnoDB:                 innodb-parameters.  (line  367)
* NFS, InnoDB <1>:                       innodb-restrictions.
                                                             (line   16)
* NFS, InnoDB:                           innodb-configuration.
                                                             (line   47)
* nice option, mysqld_safe:              mysqld-safe.        (line  171)
* no matching rows:                      no-matching-rows.   (line    6)
* no-auto-rehash option, mysql:          mysql-command-options.
                                                             (line  277)
* no-autocommit option, mysqldump:       mysqldump.          (line  586)
* no-beep option, mysql:                 mysql-command-options.
                                                             (line  283)
* no-beep option, mysqladmin:            mysqladmin.         (line  350)
* no-create-db option, mysqldump:        mysqldump.          (line  592)
* no-create-info option, mysqldump:      mysqldump.          (line  598)
* no-data option, mysqldump:             mysqldump.          (line  603)
* no-debug option, make_win_bin_dist:    make-win-bin-dist.  (line   53)
* no-defaults option:                    option-file-options.
                                                             (line   37)
* no-defaults option, my_print_defaults: my-print-defaults.  (line   53)
* no-defaults option, mysqld_multi:      mysqld-multi.       (line   62)
* no-defaults option, mysqld_safe:       mysqld-safe.        (line  176)
* no-embedded option, make_win_bin_dist: make-win-bin-dist.  (line   57)
* no-log option, mysqld_multi:           mysqld-multi.       (line  115)
* no-named-commands option, mysql:       mysql-command-options.
                                                             (line  287)
* no-pager option, mysql:                mysql-command-options.
                                                             (line  291)
* no-symlinks option, myisamchk:         myisamchk-repair-options.
                                                             (line   47)
* no-tee option, mysql:                  mysql-command-options.
                                                             (line  295)
* NO_AUTO_CREATE_USER SQL mode:          server-sql-mode.    (line  162)
* NO_AUTO_VALUE_ON_ZERO SQL mode:        server-sql-mode.    (line  168)
* NO_BACKSLASH_ESCAPES SQL mode:         server-sql-mode.    (line  187)
* NO_DIR_IN_CREATE SQL mode:             server-sql-mode.    (line  193)
* NO_ENGINE_SUBSTITUTION SQL mode:       server-sql-mode.    (line  199)
* NO_FIELD_OPTIONS SQL mode:             server-sql-mode.    (line  218)
* NO_KEY_OPTIONS SQL mode:               server-sql-mode.    (line  224)
* NO_TABLE_OPTIONS SQL mode:             server-sql-mode.    (line  230)
* NO_UNSIGNED_SUBTRACTION SQL mode:      server-sql-mode.    (line  236)
* NO_ZERO_DATE SQL mode:                 server-sql-mode.    (line  283)
* NO_ZERO_IN_DATE SQL mode:              server-sql-mode.    (line  289)
* noindices option, mysqlhotcopy:        mysqlhotcopy.       (line  120)
* non-delimited strings:                 datetime.           (line  127)
* Non-transactional tables:              non-transactional-tables.
                                                             (line    6)
* nopager command, mysql:                mysql-commands.     (line  129)
* NOT BETWEEN:                           comparison-operators.
                                                             (line  206)
* not equal (!=):                        comparison-operators.
                                                             (line   89)
* not equal (<>):                        comparison-operators.
                                                             (line   89)
* NOT EXISTS, with subqueries:           exists-and-not-exists-subqueries.
                                                             (line    6)
* NOT IN:                                comparison-operators.
                                                             (line  274)
* NOT LIKE:                              string-comparison-functions.
                                                             (line  118)
* NOT NULL, constraint:                  constraint-invalid-data.
                                                             (line    6)
* NOT REGEXP:                            regexp.             (line   26)
* NOT, logical:                          logical-operators.  (line   27)
* notee command, mysql:                  mysql-commands.     (line  135)
* Novell NetWare:                        netware-installation.
                                                             (line    6)
* NOW():                                 date-and-time-functions.
                                                             (line  698)
* nowarning command, mysql:              mysql-commands.     (line  140)
* NUL <1>:                               load-data.          (line  424)
* NUL:                                   string-syntax.      (line   55)
* NULL <1>:                              problems-with-null. (line    6)
* NULL:                                  working-with-null.  (line    6)
* NULL value <1>:                        null-values.        (line    6)
* NULL value:                            working-with-null.  (line    6)
* NULL values, and AUTO_INCREMENT columns: problems-with-null.
                                                             (line   71)
* NULL values, and indexes:              create-table.       (line  383)
* NULL values, and TIMESTAMP columns:    problems-with-null. (line   71)
* NULL values, vs. empty values:         problems-with-null. (line    6)
* NULL, ORDER BY <1>:                    select.             (line  194)
* NULL, ORDER BY:                        order-by-optimization.
                                                             (line   94)
* NULL, testing for null <1>:            control-flow-functions.
                                                             (line   84)
* NULL, testing for null:                comparison-operators.
                                                             (line   77)
* NULL, thread state:                    general-thread-states.
                                                             (line  163)
* NULLIF():                              control-flow-functions.
                                                             (line  116)
* number-blob-cols option, mysqlslap:    mysqlslap.          (line  337)
* number-char-cols option, mysqlslap:    mysqlslap.          (line  345)
* number-int-cols option, mysqlslap:     mysqlslap.          (line  350)
* number-of-queries option, mysqlslap:   mysqlslap.          (line  355)
* numbers:                               number-syntax.      (line    6)
* NUMERIC data type:                     numeric-type-overview.
                                                             (line  248)
* numeric types:                         storage-requirements.
                                                             (line   15)
* numeric-dump-file option, resolve_stack_dump: resolve-stack-dump.
                                                             (line   25)
* NumGeometries():                       geometrycollection-property-functions.
                                                             (line   21)
* NumInteriorRings():                    polygon-property-functions.
                                                             (line   49)
* NumPoints():                           linestring-property-functions.
                                                             (line   39)
* NVARCHAR data type:                    string-type-overview.
                                                             (line  121)
* obtaining information about partitions: partitioning-info. (line    6)
* OCT():                                 mathematical-functions.
                                                             (line  325)
* OCTET_LENGTH():                        string-functions.   (line  477)
* ODBC:                                  connector-odbc.     (line   17)
* ODBC compatibility <1>:                join.               (line  145)
* ODBC compatibility <2>:                create-table.       (line  274)
* ODBC compatibility <3>:                comparison-operators.
                                                             (line  151)
* ODBC compatibility <4>:                type-conversion.    (line   40)
* ODBC compatibility <5>:                numeric-type-overview.
                                                             (line  230)
* ODBC compatibility:                    identifier-qualifiers.
                                                             (line   41)
* offset option, mysqlbinlog:            mysqlbinlog.        (line  244)
* OLAP:                                  group-by-modifiers. (line    6)
* old system variable:                   server-system-variables.
                                                             (line 3056)
* old-passwords option, mysqld <1>:      privileges-options. (line   52)
* old-passwords option, mysqld:          server-options.     (line 1132)
* old-style-user-limits option, mysqld:  server-options.     (line 1150)
* OLD_PASSWORD():                        encryption-functions.
                                                             (line  242)
* old_passwords system variable:         server-system-variables.
                                                             (line 3078)
* old_server option, mysqlaccess:        mysqlaccess.        (line   96)
* ON DUPLICATE KEY UPDATE:               insert.             (line   12)
* one-database option, mysql:            mysql-command-options.
                                                             (line  300)
* one-thread option, mysqld:             server-options.     (line 1164)
* one_shot system variable:              server-system-variables.
                                                             (line 3095)
* online location of manual:             manual-info.        (line    6)
* only-debug option, make_win_bin_dist:  make-win-bin-dist.  (line   61)
* only-print option, mysqlslap:          mysqlslap.          (line  359)
* ONLY_FULL_GROUP_BY SQL mode:           server-sql-mode.    (line  298)
* ONLY_FULL_GROUP_BY, SQL mode:          group-by-hidden-columns.
                                                             (line    6)
* OPEN:                                  open.               (line    6)
* Open Source, defined:                  what-is-mysql.      (line   42)
* open tables <1>:                       table-cache.        (line    6)
* open tables:                           mysqladmin.         (line  211)
* open-files-limit option, mysqld:       server-options.     (line 1178)
* open-files-limit option, mysqld_safe:  mysqld-safe.        (line  181)
* open_files_limit option, mysqlbackup:  mysqlbackup.        (line  124)
* open_files_limit system variable:      server-system-variables.
                                                             (line 3100)
* open_files_limit variable:             mysqlbinlog.        (line  384)
* OpenGIS:                               gis-introduction.   (line    6)
* Opening master dump table, thread state: slave-connection-thread-states.
                                                             (line   18)
* Opening table, thread state:           general-thread-states.
                                                             (line  173)
* Opening tables, thread state:          general-thread-states.
                                                             (line  173)
* opening, tables:                       table-cache.        (line    6)
* opens:                                 mysqladmin.         (line  202)
* OpenSSL <1>:                           secure-using-ssl.   (line    6)
* OpenSSL:                               secure-connections. (line   13)
* operating systems, file-size limits:   full-table.         (line    6)
* operating systems, supported:          which-os.           (line    6)
* operating systems, Windows versus Unix: windows-vs-unix.   (line    6)
* operations, arithmetic:                arithmetic-functions.
                                                             (line   44)
* operators:                             functions.          (line   23)
* operators, assignment:                 user-variables.     (line    6)
* operators, cast <1>:                   cast-functions.     (line    6)
* operators, cast:                       arithmetic-functions.
                                                             (line    6)
* operators, logical:                    logical-operators.  (line    6)
* operators, precedence:                 operator-precedence.
                                                             (line    6)
* opt option, mysqldump:                 mysqldump.          (line  609)
* optimization, Batched Key Access <1>:  bka-optimization.   (line    6)
* optimization, Batched Key Access:      bnl-bka-optimization.
                                                             (line   12)
* optimization, Block Nested-Loop <1>:   bnl-optimization.   (line    6)
* optimization, Block Nested-Loop:       bnl-bka-optimization.
                                                             (line   12)
* optimization, Multi-Range Read:        mrr-optimization.   (line    6)
* optimization, subquery:                in-subquery-optimization.
                                                             (line    6)
* optimization, tips:                    miscellaneous-optimization-tips.
                                                             (line    6)
* optimizations <1>:                     index-merge-optimization.
                                                             (line   12)
* optimizations:                         where-optimizations.
                                                             (line    6)
* optimize option, mysqlcheck:           mysqlcheck.         (line  285)
* OPTIMIZE TABLE:                        optimize-table.     (line    6)
* OPTIMIZE TABLE, and partitioning:      partitioning-maintenance.
                                                             (line    6)
* optimizer, and replication:            replication-features-optimizer.
                                                             (line    6)
* optimizer, controlling:                controlling-optimizer.
                                                             (line    6)
* optimizer_prune_level system variable: server-system-variables.
                                                             (line 3122)
* optimizer_search_depth system variable: server-system-variables.
                                                             (line 3141)
* optimizer_switch system variable <1>:  switchable-optimizations.
                                                             (line    6)
* optimizer_switch system variable:      server-system-variables.
                                                             (line 3166)
* optimizer_use_mrr system variable:     server-system-variables.
                                                             (line 3233)
* optimizing, DISTINCT:                  distinct-optimization.
                                                             (line    6)
* optimizing, filesort:                  order-by-optimization.
                                                             (line  109)
* optimizing, GROUP BY:                  group-by-optimization.
                                                             (line   11)
* optimizing, LEFT JOIN:                 left-join-optimization.
                                                             (line    6)
* optimizing, LIMIT:                     limit-optimization. (line    6)
* optimizing, tables:                    table-optimization. (line    6)
* option files <1>:                      access-denied.      (line  108)
* option files:                          option-files.       (line   11)
* option modifiers:                      option-modifiers.   (line    6)
* options, command-line, mysql:          mysql-command-options.
                                                             (line    6)
* options, command-line, mysqladmin:     mysqladmin.         (line  232)
* options, configure:                    configure-options.  (line    6)
* options, embedded server:              libmysqld-options.  (line    6)
* options, libmysqld:                    libmysqld-options.  (line    6)
* options, myisamchk:                    myisamchk-general-options.
                                                             (line    6)
* options, provided by MySQL:            tutorial.           (line   17)
* options, replication:                  replication-features.
                                                             (line   38)
* OR <1>:                                index-merge-optimization.
                                                             (line   12)
* OR:                                    searching-on-two-keys.
                                                             (line    6)
* OR Index Merge optimization:           index-merge-optimization.
                                                             (line   12)
* OR, bitwise:                           bit-functions.      (line   18)
* OR, logical:                           logical-operators.  (line   63)
* Oracle compatibility <1>:              describe.           (line   32)
* Oracle compatibility <2>:              group-by-functions. (line  227)
* Oracle compatibility:                  extensions-to-ansi. (line   96)
* ORACLE SQL mode:                       server-sql-mode.    (line  471)
* ORD():                                 string-functions.   (line  481)
* ORDER BY <1>:                          select.             (line  166)
* ORDER BY <2>:                          alter-table.        (line  325)
* ORDER BY:                              sorting-rows.       (line    6)
* ORDER BY, NULL <1>:                    select.             (line  194)
* ORDER BY, NULL:                        order-by-optimization.
                                                             (line   94)
* order-by-primary option, mysqldump:    mysqldump.          (line  623)
* out_dir option, comp_err:              comp-err.           (line   57)
* out_file option, comp_err:             comp-err.           (line   62)
* OUTFILE:                               select.             (line  325)
* Overlaps():                            functions-that-test-spatial-relationships-between-geometries.
                                                             (line   62)
* overview:                              introduction.       (line   17)
* packages, list of:                     packages.           (line    6)
* PAD_CHAR_TO_FULL_LENGTH SQL mode:      server-sql-mode.    (line  310)
* pager command, mysql:                  mysql-commands.     (line  144)
* pager option, mysql:                   mysql-command-options.
                                                             (line  306)
* parallel-recover option, myisamchk:    myisamchk-repair-options.
                                                             (line   59)
* PARAMETERS, INFORMATION_SCHEMA table:  parameters-table.   (line    6)
* parameters, server:                    server-parameters.  (line    6)
* parentheses ( and ):                   operator-precedence.
                                                             (line   37)
* PARTITION:                             partitioning.       (line   14)
* partition management:                  partitioning-management.
                                                             (line   13)
* partition pruning:                     partitioning-pruning.
                                                             (line    6)
* partitioning:                          partitioning.       (line   14)
* partitioning information statements:   partitioning-info.  (line    6)
* partitioning keys and primary keys:    partitioning-limitations-partitioning-keys-unique-keys.
                                                             (line    6)
* partitioning keys and unique keys:     partitioning-limitations-partitioning-keys-unique-keys.
                                                             (line    6)
* partitioning, advantages:              partitioning-overview.
                                                             (line  125)
* partitioning, and dates:               partitioning-types. (line   39)
* partitioning, and foreign keys:        partitioning-limitations.
                                                             (line  222)
* partitioning, and FULLTEXT indexes:    partitioning-limitations.
                                                             (line  241)
* partitioning, and key cache:           partitioning-limitations.
                                                             (line  293)
* partitioning, and server SQL mode:     partitioning-limitations.
                                                             (line   45)
* partitioning, and subqueries:          partitioning-limitations.
                                                             (line  283)
* partitioning, and temporary tables <1>: partitioning-limitations-partitioning-keys-unique-keys.
                                                             (line    6)
* partitioning, and temporary tables:    partitioning-limitations.
                                                             (line  251)
* partitioning, by hash:                 partitioning-hash.  (line   10)
* partitioning, by key:                  partitioning-key.   (line    6)
* partitioning, by linear hash:          partitioning-linear-hash.
                                                             (line    6)
* partitioning, by linear key:           partitioning-key.   (line   83)
* partitioning, by list:                 partitioning-list.  (line    6)
* partitioning, by range:                partitioning-range. (line    6)
* partitioning, concepts:                partitioning-overview.
                                                             (line    6)
* partitioning, data type of partitioning key: partitioning-limitations.
                                                             (line  262)
* partitioning, enabling:                partitioning.       (line   14)
* partitioning, functions supported in partitioning expressions: partitioning-limitations-functions.
                                                             (line    9)
* partitioning, limitations:             partitioning-limitations.
                                                             (line   15)
* Partitioning, maximum number of partitions: partitioning-limitations.
                                                             (line  210)
* partitioning, operators disallowed in partitioning expressions: partitioning-limitations.
                                                             (line   29)
* partitioning, operators supported in partitioning expressions: partitioning-limitations.
                                                             (line   29)
* partitioning, optimization <1>:        partitioning-pruning.
                                                             (line    6)
* partitioning, optimization:            partitioning-info.  (line   53)
* partitioning, resources:               partitioning.       (line   96)
* partitioning, storage engines (limitations): partitioning-limitations-storage-engines.
                                                             (line    6)
* partitioning, subpartitioning:         partitioning-limitations.
                                                             (line  288)
* partitioning, support:                 partitioning.       (line   14)
* partitioning, types:                   partitioning-types. (line   15)
* partitions, adding and dropping:       partitioning-management.
                                                             (line   13)
* partitions, analyzing:                 partitioning-maintenance.
                                                             (line    6)
* partitions, checking:                  partitioning-maintenance.
                                                             (line    6)
* PARTITIONS, INFORMATION_SCHEMA table:  partitions-table.   (line    6)
* partitions, managing:                  partitioning-management.
                                                             (line   13)
* partitions, modifying:                 partitioning-management.
                                                             (line   13)
* partitions, optimizing:                partitioning-maintenance.
                                                             (line    6)
* partitions, repairing:                 partitioning-maintenance.
                                                             (line    6)
* partitions, splitting and merging:     partitioning-management.
                                                             (line   13)
* password encryption, reversibility of: encryption-functions.
                                                             (line  263)
* password option:                       connecting.         (line  134)
* password option, mysql:                mysql-command-options.
                                                             (line  315)
* password option, mysql_convert_table_format: mysql-convert-table-format.
                                                             (line   36)
* password option, mysql_setpermission:  mysql-setpermission.
                                                             (line   37)
* password option, mysqlaccess:          mysqlaccess.        (line  101)
* password option, mysqladmin:           mysqladmin.         (line  355)
* password option, mysqlbinlog:          mysqlbinlog.        (line  248)
* password option, mysqlcheck:           mysqlcheck.         (line  289)
* password option, mysqld_multi:         mysqld-multi.       (line  120)
* password option, mysqldump:            mysqldump.          (line  630)
* password option, mysqlhotcopy:         mysqlhotcopy.       (line  126)
* password option, mysqlimport:          mysqlimport.        (line  215)
* password option, mysqlshow:            mysqlshow.          (line  147)
* password option, mysqlslap:            mysqlslap.          (line  364)
* PASSWORD() <1>:                        ignoring-user.      (line   26)
* PASSWORD() <2>:                        encryption-functions.
                                                             (line  252)
* PASSWORD() <3>:                        passwords.          (line    6)
* PASSWORD():                            connection-access.  (line   38)
* password, root user:                   default-privileges. (line    6)
* passwords, administrator guidelines:   password-security-admin.
                                                             (line    6)
* passwords, for users:                  user-names.         (line    6)
* passwords, forgotten:                  resetting-permissions.
                                                             (line   11)
* passwords, hashing:                    password-hashing.   (line    6)
* passwords, lost:                       resetting-permissions.
                                                             (line   11)
* passwords, resetting:                  resetting-permissions.
                                                             (line   11)
* passwords, security <1>:               password-security.  (line   13)
* passwords, security:                   privilege-system.   (line   16)
* passwords, setting <1>:                set-password.       (line    6)
* passwords, setting <2>:                grant.              (line  347)
* passwords, setting:                    passwords.          (line    6)
* passwords, user guidelines:            password-security-user.
                                                             (line    6)
* PATH environment variable <1>:         invoking-programs.  (line   48)
* PATH environment variable <2>:         environment-variables.
                                                             (line   18)
* PATH environment variable:             installing-binary.  (line  115)
* pattern matching <1>:                  regexp.             (line    6)
* pattern matching:                      pattern-matching.   (line    6)
* performance, benchmarks:               custom-benchmarks.  (line    6)
* performance, disk issues:              disk-issues.        (line   10)
* performance, estimating:               estimating-performance.
                                                             (line    6)
* performance, improving <1>:            replication-faq.    (line   29)
* performance, improving:                data-size.          (line    6)
* PERIOD_ADD():                          date-and-time-functions.
                                                             (line  739)
* PERIOD_DIFF():                         date-and-time-functions.
                                                             (line  748)
* Perl API:                              apis-perl.          (line    6)
* Perl DBI/DBD, installation problems:   perl-support-problems.
                                                             (line    6)
* Perl, installing:                      perl-support.       (line   12)
* Perl, installing on Windows:           activestate-perl.   (line    6)
* permission checks, effect on speed:    query-speed.        (line   36)
* perror <1>:                            perror.             (line    6)
* perror:                                programs-overview.  (line  256)
* perror, help option:                   perror.             (line   35)
* perror, silent option:                 perror.             (line   39)
* perror, verbose option:                perror.             (line   43)
* perror, version option:                perror.             (line   48)
* phantom rows:                          innodb-next-key-locking.
                                                             (line    6)
* PHP API:                               apis-php.           (line   12)
* PI():                                  mathematical-functions.
                                                             (line  334)
* pid-file option, mysql.server:         mysql-server.       (line   44)
* pid-file option, mysqld:               server-options.     (line 1206)
* pid-file option, mysqld_safe:          mysqld-safe.        (line  188)
* pid_file system variable:              server-system-variables.
                                                             (line 3267)
* Ping, thread command:                  thread-commands.    (line   78)
* pipe option:                           connecting.         (line  141)
* pipe option, mysql <1>:                mysqlcheck.         (line  300)
* pipe option, mysql:                    mysql-command-options.
                                                             (line  326)
* pipe option, mysqladmin:               mysqladmin.         (line  366)
* pipe option, mysqldump:                mysqldump.          (line  641)
* pipe option, mysqlimport:              mysqlimport.        (line  226)
* pipe option, mysqlshow:                mysqlshow.          (line  158)
* pipe option, mysqlslap:                mysqlslap.          (line  377)
* PIPES_AS_CONCAT SQL mode:              server-sql-mode.    (line  347)
* plan option, mysqlaccess:              mysqlaccess.        (line  110)
* plugin API:                            plugin-api.         (line   12)
* plugin-load option, mysqld:            server-options.     (line 1223)
* plugin_dir system variable:            server-system-variables.
                                                             (line 3283)
* plugindir option, mysql_config:        mysql-config.       (line   39)
* plugins, adding:                       plugin-api.         (line   12)
* PLUGINS, INFORMATION_SCHEMA table:     plugins-table.      (line    6)
* plugins, installing:                   install-plugin.     (line    6)
* plugins, uninstalling:                 uninstall-plugin.   (line    6)
* POINT data type:                       mysql-spatial-datatypes.
                                                             (line    6)
* point in time recovery:                point-in-time-recovery.
                                                             (line   11)
* Point():                               gis-mysql-specific-functions.
                                                             (line   44)
* PointFromText():                       gis-wkt-functions.  (line   45)
* PointFromWKB():                        gis-wkb-functions.  (line   46)
* PointN():                              linestring-property-functions.
                                                             (line   51)
* PointOnSurface():                      multipolygon-property-functions.
                                                             (line   32)
* PolyFromText():                        gis-wkt-functions.  (line   49)
* PolyFromWKB():                         gis-wkb-functions.  (line   50)
* POLYGON data type:                     mysql-spatial-datatypes.
                                                             (line    6)
* Polygon():                             gis-mysql-specific-functions.
                                                             (line   48)
* PolygonFromText():                     gis-wkt-functions.  (line   49)
* PolygonFromWKB():                      gis-wkb-functions.  (line   50)
* port option:                           connecting.         (line  148)
* port option, mysql:                    mysql-command-options.
                                                             (line  332)
* port option, mysql_config:             mysql-config.       (line   44)
* port option, mysql_convert_table_format: mysql-convert-table-format.
                                                             (line   46)
* port option, mysql_setpermission:      mysql-setpermission.
                                                             (line   47)
* port option, mysqladmin:               mysqladmin.         (line  372)
* port option, mysqlbinlog:              mysqlbinlog.        (line  259)
* port option, mysqlcheck:               mysqlcheck.         (line  306)
* port option, mysqld:                   server-options.     (line 1259)
* port option, mysqld_safe:              mysqld-safe.        (line  192)
* port option, mysqldump:                mysqldump.          (line  647)
* port option, mysqlhotcopy:             mysqlhotcopy.       (line  136)
* port option, mysqlimport:              mysqlimport.        (line  232)
* port option, mysqlshow:                mysqlshow.          (line  164)
* port option, mysqlslap:                mysqlslap.          (line  383)
* port system variable:                  server-system-variables.
                                                             (line 3299)
* port-open-timeout option, mysqld:      server-options.     (line 1277)
* portability:                           portability.        (line    6)
* portability, types:                    other-vendor-data-types.
                                                             (line    6)
* porting, to other systems:             porting.            (line   14)
* position option, mysqlbinlog:          mysqlbinlog.        (line  263)
* POSITION():                            string-functions.   (line  497)
* post-install, multiple servers:        multiple-servers.   (line   12)
* post-installation, setup and testing:  post-installation.  (line   12)
* post-query option, mysqlslap:          mysqlslap.          (line  387)
* post-system option, mysqlslap:         mysqlslap.          (line  399)
* PostgreSQL compatibility:              extensions-to-ansi. (line  194)
* POSTGRESQL SQL mode:                   server-sql-mode.    (line  477)
* POW():                                 mathematical-functions.
                                                             (line  345)
* POWER():                               mathematical-functions.
                                                             (line  354)
* pre-query option, mysqlslap:           mysqlslap.          (line  404)
* pre-system option, mysqlslap:          mysqlslap.          (line  410)
* precedence, operator:                  operator-precedence.
                                                             (line    6)
* precision math:                        precision-math.     (line   14)
* precision, arithmetic:                 precision-math.     (line   14)
* prefix option, configure:              configure-options.  (line  321)
* preload_buffer_size system variable:   server-system-variables.
                                                             (line 3316)
* PREPARE <1>:                           prepare.            (line    6)
* PREPARE:                               sql-syntax-prepared-statements.
                                                             (line   13)
* Prepare, thread command:               thread-commands.    (line   82)
* PREPARE, XA transactions:              xa-statements.      (line    6)
* prepared statements <1>:               c-api-prepared-statements.
                                                             (line    6)
* prepared statements <2>:               deallocate-prepare. (line    6)
* prepared statements <3>:               execute.            (line    6)
* prepared statements <4>:               prepare.            (line    6)
* prepared statements:                   sql-syntax-prepared-statements.
                                                             (line   13)
* prepared statements, repreparation:    statement-repreparation.
                                                             (line    6)
* preparing, thread state:               general-thread-states.
                                                             (line  181)
* preserve-schema option, mysqlslap:     mysqlslap.          (line  415)
* preview option, mysqlaccess:           mysqlaccess.        (line  114)
* PRIMARY KEY <1>:                       create-table.       (line  333)
* PRIMARY KEY:                           alter-table.        (line  307)
* primary key, constraint:               constraint-primary-key.
                                                             (line    6)
* primary key, deleting:                 alter-table.        (line  304)
* primary keys, and partitioning keys:   partitioning-limitations-partitioning-keys-unique-keys.
                                                             (line    6)
* print command, mysql:                  mysql-commands.     (line  165)
* print-defaults option:                 option-file-options.
                                                             (line   43)
* privilege information, location:       grant-table-structure.
                                                             (line    6)
* privilege system:                      privilege-system.   (line   16)
* privilege, changes:                    privilege-changes.  (line    6)
* privileges, access:                    privilege-system.   (line   16)
* privileges, adding:                    adding-users.       (line    6)
* privileges, and replication:           replication-features-mysqldb.
                                                             (line    6)
* privileges, default:                   default-privileges. (line    6)
* privileges, deleting <1>:              drop-user.          (line    6)
* privileges, deleting:                  removing-users.     (line    6)
* privileges, display:                   show-grants.        (line    6)
* privileges, dropping <1>:              drop-user.          (line    6)
* privileges, dropping:                  removing-users.     (line    6)
* privileges, granting:                  grant.              (line    6)
* privileges, revoking:                  revoke.             (line    6)
* problems, access denied errors:        error-access-denied.
                                                             (line    6)
* problems, common errors:               problems.           (line   17)
* problems, compiling:                   compilation-problems.
                                                             (line    6)
* problems, DATE columns:                using-date.         (line    6)
* problems, date values:                 datetime.           (line  166)
* problems, installing on IBM-AIX:       ibm-aix.            (line    6)
* problems, installing on Solaris:       solaris.            (line   11)
* problems, installing Perl:             perl-support-problems.
                                                             (line    6)
* problems, linking:                     link-errors.        (line    6)
* problems, lost connection errors:      error-lost-connection.
                                                             (line    6)
* problems, ODBC:                        connector-odbc-support.
                                                             (line   14)
* problems, reporting:                   bug-reports.        (line    6)
* problems, starting the server:         starting-server.    (line    6)
* problems, table locking:               table-locking.      (line    6)
* problems, time zone:                   timezone-problems.  (line    6)
* PROCEDURE:                             select.             (line  321)
* procedures, adding:                    adding-procedures.  (line   11)
* procedures, stored <1>:                stored-routines.    (line   13)
* procedures, stored:                    ansi-diff-triggers. (line    6)
* process support:                       which-os.           (line    6)
* processes, display:                    show-processlist.   (line    6)
* processing, arguments:                 udf-arguments.      (line    6)
* PROCESSLIST:                           show-processlist.   (line    6)
* PROCESSLIST, INFORMATION_SCHEMA table: processlist-table.  (line    6)
* Processlist, thread command:           thread-commands.    (line   86)
* profiling session variable:            server-session-variables.
                                                             (line  141)
* PROFILING, INFORMATION_SCHEMA table:   profiling-table.    (line    6)
* profiling_history_size session variable: server-session-variables.
                                                             (line  149)
* program variables, setting:            program-variables.  (line    6)
* program-development utilities:         programs-overview.  (line  233)
* programs, administrative:              programs-overview.  (line  152)
* programs, client <1>:                  building-clients.   (line    6)
* programs, client:                      programs-overview.  (line  111)
* programs, crash-me:                    portability.        (line    6)
* programs, stored <1>:                  stored-programs-views.
                                                             (line   15)
* programs, stored:                      sql-syntax-compound-statements.
                                                             (line   17)
* programs, utility:                     programs-overview.  (line  152)
* prompt command, mysql:                 mysql-commands.     (line  169)
* prompt option, mysql:                  mysql-command-options.
                                                             (line  336)
* prompts, meanings:                     entering-queries.   (line  134)
* pronunciation, MySQL:                  what-is-mysql.      (line   87)
* protocol option:                       connecting.         (line  153)
* protocol option, mysql:                mysql-command-options.
                                                             (line  342)
* protocol option, mysqladmin:           mysqladmin.         (line  376)
* protocol option, mysqlbinlog:          mysqlbinlog.        (line  267)
* protocol option, mysqlcheck:           mysqlcheck.         (line  310)
* protocol option, mysqldump:            mysqldump.          (line  651)
* protocol option, mysqlimport:          mysqlimport.        (line  236)
* protocol option, mysqlshow:            mysqlshow.          (line  168)
* protocol option, mysqlslap:            mysqlslap.          (line  421)
* protocol_version system variable:      server-system-variables.
                                                             (line 3333)
* PURGE BACKUP LOGS:                     purge-backup-logs.  (line    6)
* PURGE BINARY LOGS:                     purge-binary-logs.  (line    6)
* PURGE MASTER LOGS:                     purge-binary-logs.  (line    6)
* Purging old relay logs, thread state:  general-thread-states.
                                                             (line  185)
* Python API:                            apis-python.        (line    6)
* QUARTER():                             date-and-time-functions.
                                                             (line  757)
* queries, entering:                     entering-queries.   (line    6)
* queries, estimating performance:       estimating-performance.
                                                             (line    6)
* queries, examples:                     examples.           (line   18)
* queries, speed of:                     query-speed.        (line   36)
* queries, Twin Studies project:         twin.               (line   11)
* Query Cache:                           query-cache.        (line   13)
* query end, thread state:               general-thread-states.
                                                             (line  189)
* query option, mysqlslap:               mysqlslap.          (line  428)
* Query, thread command:                 thread-commands.    (line   90)
* query_alloc_block_size system variable: server-system-variables.
                                                             (line 3343)
* query_cache_limit system variable:     server-system-variables.
                                                             (line 3369)
* query_cache_min_res_unit system variable: server-system-variables.
                                                             (line 3393)
* query_cache_size system variable:      server-system-variables.
                                                             (line 3418)
* query_cache_type system variable:      server-system-variables.
                                                             (line 3451)
* query_cache_wlock_invalidate system variable: server-system-variables.
                                                             (line 3486)
* query_prealloc_size system variable:   server-system-variables.
                                                             (line 3508)
* questions:                             mysqladmin.         (line  192)
* questions, answering:                  mailing-list-use.   (line    6)
* Queueing master event to the relay log, thread state: slave-io-thread-states.
                                                             (line   58)
* quick option, myisamchk:               myisamchk-repair-options.
                                                             (line   65)
* quick option, mysql:                   mysql-command-options.
                                                             (line  349)
* quick option, mysqlcheck:              mysqlcheck.         (line  317)
* quick option, mysqldump:               mysqldump.          (line  658)
* quiet option, mysqlhotcopy:            mysqlhotcopy.       (line  140)
* quit command, mysql:                   mysql-commands.     (line  178)
* Quit, thread command:                  thread-commands.    (line   94)
* QUOTE():                               string-functions.   (line  501)
* quote-names option, mysqldump:         mysqldump.          (line  665)
* quotes, in strings:                    string-syntax.      (line   92)
* quoting:                               string-syntax.      (line  140)
* quoting binary data:                   string-syntax.      (line  130)
* quoting of identifiers:                identifiers.        (line   20)
* RADIANS():                             mathematical-functions.
                                                             (line  358)
* RAND():                                mathematical-functions.
                                                             (line  366)
* rand_seed1 session variable:           server-session-variables.
                                                             (line  157)
* rand_seed2 session variable:           server-session-variables.
                                                             (line  171)
* range join type, optimizer:            using-explain.      (line  238)
* range partitioning:                    partitioning-range. (line    6)
* range partitions, adding and dropping: partitioning-management-range-list.
                                                             (line    6)
* range partitions, managing:            partitioning-management-range-list.
                                                             (line    6)
* range_alloc_block_size system variable: server-system-variables.
                                                             (line 3536)
* raw option, mysql:                     mysql-command-options.
                                                             (line  355)
* re-creating, grant tables:             mysql-install-db-problems.
                                                             (line  103)
* READ COMMITTED, transaction isolation level: set-transaction.
                                                             (line   69)
* READ UNCOMMITTED, transaction isolation level: set-transaction.
                                                             (line   61)
* read-from-remote-server option, mysqlbinlog: mysqlbinlog.  (line  274)
* read-only option, myisamchk:           myisamchk-check-options.
                                                             (line   50)
* read-only option, mysqld:              replication-options-slave.
                                                             (line  166)
* read_buffer_size myisamchk variable:   myisamchk-general-options.
                                                             (line   53)
* read_buffer_size system variable:      server-system-variables.
                                                             (line 3555)
* read_only system variable:             server-system-variables.
                                                             (line 3583)
* read_rnd_buffer_size system variable:  server-system-variables.
                                                             (line 3630)
* Reading event from the relay log, thread state: slave-sql-thread-states.
                                                             (line   13)
* Reading from net, thread state:        general-thread-states.
                                                             (line  194)
* Reading master dump table data, thread state: slave-connection-thread-states.
                                                             (line   22)
* REAL data type:                        numeric-type-overview.
                                                             (line  209)
* REAL_AS_FLOAT SQL mode:                server-sql-mode.    (line  352)
* Rebuilding the index on master dump table, thread state: slave-connection-thread-states.
                                                             (line   26)
* reconfiguring:                         compilation-problems.
                                                             (line    6)
* reconnect option, mysql:               mysql-command-options.
                                                             (line  386)
* Reconnecting after a failed binlog dump request, thread state: slave-io-thread-states.
                                                             (line   45)
* Reconnecting after a failed master event read, thread state: slave-io-thread-states.
                                                             (line   70)
* record-level locks, InnoDB <1>:        innodb-next-key-locking.
                                                             (line    6)
* record-level locks, InnoDB <2>:        innodb-record-level-locks.
                                                             (line    6)
* record-level locks, InnoDB <3>:        innodb-transaction-model.
                                                             (line   64)
* record-level locks, InnoDB:            innodb-parameters.  (line  367)
* record_log_pos option, mysqlhotcopy:   mysqlhotcopy.       (line  144)
* recover option, myisamchk:             myisamchk-repair-options.
                                                             (line   71)
* RECOVER, XA transactions:              xa-statements.      (line    6)
* recovery, from crash:                  crash-recovery.     (line    6)
* recovery, point in time:               point-in-time-recovery.
                                                             (line   11)
* reducing, data size:                   data-size.          (line    6)
* ref join type, optimizer:              using-explain.      (line  172)
* ref_or_null:                           is-null-optimization.
                                                             (line    6)
* ref_or_null join type, optimizer:      using-explain.      (line  199)
* references:                            alter-table.        (line  375)
* REFERENTIAL_CONSTRAINTS, INFORMATION_SCHEMA table: referential-constraints-table.
                                                             (line    6)
* Refresh, thread command:               thread-commands.    (line   98)
* REGEXP:                                regexp.             (line   30)
* REGEXP operator:                       regexp.             (line    6)
* regexp option, mysql_find_rows:        mysql-find-rows.    (line   35)
* regexp option, mysqlhotcopy:           mysqlhotcopy.       (line  149)
* Register Slave, thread command:        thread-commands.    (line  103)
* Registering slave on master, thread state: slave-io-thread-states.
                                                             (line   25)
* regular expression syntax:             regexp.             (line    6)
* rehash command, mysql:                 mysql-commands.     (line  182)
* Related():                             functions-that-test-spatial-relationships-between-geometries.
                                                             (line   69)
* relational databases, defined:         what-is-mysql.      (line   42)
* relative option, mysqladmin:           mysqladmin.         (line  383)
* relay-log option, mysqld:              replication-options-slave.
                                                             (line  174)
* relay-log-index option, mysqld:        replication-options-slave.
                                                             (line  206)
* relay-log-info-file option, mysqld:    replication-options-slave.
                                                             (line  227)
* relay-log-purge option, mysqld:        replication-options-slave.
                                                             (line  233)
* relay-log-recovery option, mysqld:     replication-options-slave.
                                                             (line  240)
* relay-log-space-limit option, mysqld:  replication-options-slave.
                                                             (line  249)
* relay_log_purge system variable:       server-system-variables.
                                                             (line 3660)
* relay_log_recovery system variable:    replication-options-slave.
                                                             (line  771)
* relay_log_space_limit system variable: server-system-variables.
                                                             (line 3677)
* release numbers:                       which-version.      (line   19)
* RELEASE SAVEPOINT:                     savepoint.          (line    6)
* RELEASE_LOCK():                        miscellaneous-functions.
                                                             (line  181)
* releases, naming scheme:               choosing-version.   (line   60)
* releases, testing:                     choosing-version.   (line  127)
* releases, updating:                    many-versions.      (line    6)
* relnotes option, mysqlaccess:          mysqlaccess.        (line  119)
* Removing duplicates, thread state:     general-thread-states.
                                                             (line  198)
* removing tmp table, thread state:      general-thread-states.
                                                             (line  205)
* rename result table, thread state:     general-thread-states.
                                                             (line  215)
* RENAME TABLE:                          rename-table.       (line    6)
* RENAME USER:                           rename-user.        (line    6)
* rename, thread state:                  general-thread-states.
                                                             (line  211)
* renaming user accounts:                rename-user.        (line    6)
* Reopen tables, thread state:           general-thread-states.
                                                             (line  221)
* reordering, columns:                   change-column-order.
                                                             (line    6)
* Repair by sorting, thread state:       general-thread-states.
                                                             (line  227)
* Repair done, thread state:             general-thread-states.
                                                             (line  231)
* repair option, mysqlcheck:             mysqlcheck.         (line  326)
* repair options, myisamchk:             myisamchk-repair-options.
                                                             (line    6)
* REPAIR TABLE:                          repair-table.       (line    6)
* REPAIR TABLE, and partitioning:        partitioning-maintenance.
                                                             (line    6)
* Repair with keycache, thread state:    general-thread-states.
                                                             (line  236)
* repair, tables:                        mysqlcheck.         (line    6)
* repairing, tables:                     repair.             (line    6)
* REPEAT:                                repeat-statement.   (line    6)
* REPEAT():                              string-functions.   (line  515)
* REPEATABLE READ, transaction isolation level: set-transaction.
                                                             (line  104)
* REPLACE:                               replace.            (line    6)
* replace:                               programs-overview.  (line  261)
* replace option, mysqldump:             mysqldump.          (line  674)
* replace option, mysqlimport:           mysqlimport.        (line  243)
* replace utility:                       replace-utility.    (line    6)
* REPLACE():                             string-functions.   (line  524)
* replicate-do-db option, mysqld:        replication-options-slave.
                                                             (line  270)
* replicate-do-table option, mysqld:     replication-options-slave.
                                                             (line  430)
* replicate-ignore-db option, mysqld:    replication-options-slave.
                                                             (line  373)
* replicate-ignore-table option, mysqld: replication-options-slave.
                                                             (line  437)
* replicate-rewrite-db option, mysqld:   replication-options-slave.
                                                             (line  446)
* replicate-same-server-id option, mysqld: replication-options-slave.
                                                             (line  466)
* replicate-wild-do-table option, mysqld: replication-options-slave.
                                                             (line  480)
* replicate-wild-ignore-table option, mysqld: replication-options-slave.
                                                             (line  513)
* replication:                           replication.        (line   13)
* replication formats, compared:         replication-sbr-rbr.
                                                             (line    6)
* replication implementation:            replication-implementation.
                                                             (line   12)
* replication limitations:               replication-features.
                                                             (line   38)
* replication master, thread states:     master-thread-states.
                                                             (line    6)
* replication masters:                   replication-features-mastercrash.
                                                             (line    6)
* replication masters, statements:       replication-master-sql.
                                                             (line   12)
* replication options:                   replication-features.
                                                             (line   38)
* replication slave, thread states <1>:  slave-connection-thread-states.
                                                             (line    6)
* replication slave, thread states <2>:  slave-sql-thread-states.
                                                             (line    6)
* replication slave, thread states:      slave-io-thread-states.
                                                             (line    6)
* replication slaves, statements:        replication-slave-sql.
                                                             (line   15)
* replication, and AUTO_INCREMENT:       replication-features-auto-increment.
                                                             (line    6)
* replication, and character sets:       replication-features-charset.
                                                             (line    6)
* replication, and CREATE TABLE ... SELECT: replication-features-create-select.
                                                             (line    6)
* replication, and DATA DIRECTORY:       replication-features-directory.
                                                             (line    6)
* replication, and DROP ... IF EXISTS:   replication-features-drop-if-exists.
                                                             (line    6)
* replication, and errors on slave:      replication-features-slaveerrors.
                                                             (line    6)
* replication, and floating-point values: replication-features-floatvalues.
                                                             (line    6)
* replication, and FLUSH:                replication-features-flush.
                                                             (line    6)
* replication, and functions:            replication-features-functions.
                                                             (line    6)
* replication, and INDEX DIRECTORY:      replication-features-directory.
                                                             (line    6)
* replication, and invoked features:     replication-features-invoked.
                                                             (line    6)
* replication, and LAST_INSERT_ID():     replication-features-auto-increment.
                                                             (line    6)
* replication, and LIMIT:                replication-features-limit.
                                                             (line    6)
* replication, and LOAD DATA:            replication-features-load-data.
                                                             (line    6)
* replication, and MEMORY tables:        replication-features-memory.
                                                             (line    6)
* replication, and mysql (system) database: replication-features-mysqldb.
                                                             (line    6)
* replication, and partial updates:      replication-features-transactions.
                                                             (line    6)
* replication, and privileges:           replication-features-mysqldb.
                                                             (line    6)
* replication, and query optimizer:      replication-features-optimizer.
                                                             (line    6)
* replication, and reserved words:       replication-features-reserved-words.
                                                             (line    6)
* replication, and scheduled events:     replication-features-invoked.
                                                             (line    6)
* replication, and slow query log:       replication-features-logging.
                                                             (line    6)
* replication, and stored routines:      replication-features-invoked.
                                                             (line    6)
* replication, and temporary tables:     replication-features-temptables.
                                                             (line    6)
* replication, and time zones:           replication-features-timezone.
                                                             (line    6)
* replication, and TIMESTAMP:            replication-features-auto-increment.
                                                             (line    6)
* replication, and transactions <1>:     replication-features-transactions.
                                                             (line    6)
* replication, and transactions:         replication-features-timeout.
                                                             (line    6)
* replication, and triggers <1>:         replication-features-triggers.
                                                             (line    6)
* replication, and triggers:             replication-features-invoked.
                                                             (line    6)
* replication, and TRUNCATE:             replication-features-truncate.
                                                             (line    6)
* replication, and variables:            replication-features-variables.
                                                             (line    6)
* replication, and views:                replication-features-views.
                                                             (line    6)
* replication, attribute promotion:      replication-features-different-data-types.
                                                             (line   14)
* replication, crashes:                  replication-features-mastercrash.
                                                             (line    6)
* replication, row-based vs statement-based: replication-sbr-rbr.
                                                             (line    6)
* replication, semisynchronous:          replication-semisync.
                                                             (line   12)
* replication, shutdown and restart <1>: replication-features-temptables.
                                                             (line    6)
* replication, shutdown and restart <2>: replication-features-slaveshutdown.
                                                             (line    6)
* replication, shutdown and restart:     replication-features-mastershutdown.
                                                             (line    6)
* replication, statements incompatible with STATEMENT mode: replication-sbr-rbr.
                                                             (line   31)
* replication, timeouts:                 replication-features-timeout.
                                                             (line    6)
* replication, with differing tables on master and slave: replication-features-differing-tables.
                                                             (line   11)
* report-host option, mysqld:            replication-options-slave.
                                                             (line  530)
* report-password option, mysqld:        replication-options-slave.
                                                             (line  542)
* report-port option, mysqld:            replication-options-slave.
                                                             (line  549)
* report-user option, mysqld:            replication-options-slave.
                                                             (line  557)
* report_host system variable:           server-system-variables.
                                                             (line 3700)
* report_password system variable:       server-system-variables.
                                                             (line 3705)
* report_port system variable:           server-system-variables.
                                                             (line 3710)
* report_user system variable:           server-system-variables.
                                                             (line 3715)
* reporting, bugs:                       bug-reports.        (line    6)
* reporting, Connector/NET problems:     connect-net-support.
                                                             (line   12)
* reporting, Connector/ODBC problems:    connector-odbc-support.
                                                             (line   14)
* reporting, errors <1>:                 bug-reports.        (line    6)
* reporting, errors:                     introduction.       (line   77)
* Requesting binlog dump, thread state:  slave-io-thread-states.
                                                             (line   30)
* REQUIRE GRANT option:                  grant.              (line  443)
* reschedule, thread state:              delayed-insert-thread-states.
                                                             (line   78)
* reserved words:                        reserved-words.     (line    6)
* reserved words, and replication:       replication-features-reserved-words.
                                                             (line    6)
* RESET MASTER:                          reset-master.       (line    6)
* RESET SLAVE:                           reset-slave.        (line    6)
* Reset stmt, thread command:            thread-commands.    (line  107)
* resetmaster option, mysqlhotcopy:      mysqlhotcopy.       (line  154)
* resetslave option, mysqlhotcopy:       mysqlhotcopy.       (line  158)
* RESIGNAL:                              resignal.           (line   13)
* resolve_stack_dump <1>:                resolve-stack-dump. (line    6)
* resolve_stack_dump:                    programs-overview.  (line  249)
* resolve_stack_dump, help option:       resolve-stack-dump. (line   21)
* resolve_stack_dump, numeric-dump-file option: resolve-stack-dump.
                                                             (line   25)
* resolve_stack_dump, symbols-file option: resolve-stack-dump.
                                                             (line   29)
* resolve_stack_dump, version option:    resolve-stack-dump. (line   33)
* resolveip <1>:                         resolveip.          (line    6)
* resolveip:                             programs-overview.  (line  266)
* resolveip, help option:                resolveip.          (line   16)
* resolveip, silent option:              resolveip.          (line   20)
* resolveip, version option:             resolveip.          (line   24)
* restarting, the server:                unix-post-installation.
                                                             (line  178)
* RESTORE:                               restore.            (line    6)
* RESTORE restrictions:                  backup-database-restore-restrictions.
                                                             (line    6)
* restrictions, BACKUP DATABASE:         backup-database-restore-restrictions.
                                                             (line    6)
* restrictions, events:                  stored-program-restrictions.
                                                             (line    6)
* restrictions, RESTORE:                 backup-database-restore-restrictions.
                                                             (line    6)
* restrictions, server-side cursors:     cursor-restrictions.
                                                             (line    6)
* restrictions, signal:                  signal-restrictions.
                                                             (line    6)
* restrictions, stored routines:         stored-program-restrictions.
                                                             (line    6)
* restrictions, subqueries:              subquery-restrictions.
                                                             (line    6)
* restrictions, triggers:                stored-program-restrictions.
                                                             (line    6)
* restrictions, views:                   view-restrictions.  (line    6)
* result-file option, mysqlbinlog:       mysqlbinlog.        (line  285)
* result-file option, mysqldump:         mysqldump.          (line  679)
* retrieving, data from tables:          retrieving-data.    (line   18)
* RETURN:                                return.             (line    6)
* return (\r) <1>:                       load-data.          (line  427)
* return (\r):                           string-syntax.      (line   60)
* return values, UDFs:                   udf-return-values.  (line    6)
* REVERSE():                             string-functions.   (line  535)
* REVOKE:                                revoke.             (line    6)
* revoking, privileges:                  revoke.             (line    6)
* rhost option, mysqlaccess:             mysqlaccess.        (line  123)
* RIGHT JOIN:                            join.               (line    6)
* RIGHT OUTER JOIN:                      join.               (line    6)
* RIGHT():                               string-functions.   (line  544)
* RLIKE:                                 regexp.             (line   30)
* ROLLBACK <1>:                          commit.             (line    6)
* ROLLBACK:                              ansi-diff-transactions.
                                                             (line    6)
* rollback option, mysqlaccess:          mysqlaccess.        (line  127)
* ROLLBACK TO SAVEPOINT:                 savepoint.          (line    6)
* ROLLBACK, XA transactions:             xa-statements.      (line    6)
* Rolling back, thread state:            general-thread-states.
                                                             (line  241)
* ROLLUP:                                group-by-modifiers. (line    6)
* root password:                         default-privileges. (line    6)
* root user, password resetting:         resetting-permissions.
                                                             (line   11)
* ROUND():                               mathematical-functions.
                                                             (line  454)
* rounding:                              precision-math.     (line   14)
* rounding errors:                       numeric-type-overview.
                                                             (line  139)
* routines option, mysqldump:            mysqldump.          (line  687)
* ROUTINES, INFORMATION_SCHEMA table:    routines-table.     (line    6)
* ROW:                                   row-subqueries.     (line    6)
* row subqueries:                        row-subqueries.     (line    6)
* row-based replication, advantages:     replication-sbr-rbr.
                                                             (line  115)
* row-based replication, disadvantages:  replication-sbr-rbr.
                                                             (line  151)
* row-level locking:                     internal-locking.   (line    6)
* ROW_COUNT():                           information-functions.
                                                             (line  434)
* rows option, mysql_find_rows:          mysql-find-rows.    (line   39)
* rows, counting:                        counting-rows.      (line    6)
* rows, deleting:                        deleting-from-related-tables.
                                                             (line    6)
* rows, locking:                         ansi-diff-transactions.
                                                             (line  173)
* rows, matching problems:               no-matching-rows.   (line    6)
* rows, selecting:                       selecting-rows.     (line    6)
* rows, sorting:                         sorting-rows.       (line    6)
* RPAD():                                string-functions.   (line  554)
* Rpl_semi_sync_master_clients status variable: server-status-variables.
                                                             (line 1043)
* rpl_semi_sync_master_enabled system variable: server-system-variables.
                                                             (line 3720)
* Rpl_semi_sync_master_net_avg_wait_time status variable: server-status-variables.
                                                             (line 1050)
* Rpl_semi_sync_master_net_wait_time status variable: server-status-variables.
                                                             (line 1057)
* Rpl_semi_sync_master_net_waits status variable: server-status-variables.
                                                             (line 1064)
* Rpl_semi_sync_master_no_times status variable: server-status-variables.
                                                             (line 1071)
* Rpl_semi_sync_master_no_tx status variable: server-status-variables.
                                                             (line 1078)
* rpl_semi_sync_master_reply_log_file_pos system variable: server-system-variables.
                                                             (line 3729)
* Rpl_semi_sync_master_status status variable: server-status-variables.
                                                             (line 1086)
* Rpl_semi_sync_master_timefunc_failures status variable: server-status-variables.
                                                             (line 1097)
* rpl_semi_sync_master_timeout system variable: server-system-variables.
                                                             (line 3736)
* rpl_semi_sync_master_trace_level system variable: server-system-variables.
                                                             (line 3746)
* Rpl_semi_sync_master_tx_avg_wait_time status variable: server-status-variables.
                                                             (line 1104)
* Rpl_semi_sync_master_tx_wait_time status variable: server-status-variables.
                                                             (line 1111)
* Rpl_semi_sync_master_tx_waits status variable: server-status-variables.
                                                             (line 1118)
* Rpl_semi_sync_master_wait_pos_backtraverse status variable: server-status-variables.
                                                             (line 1125)
* Rpl_semi_sync_master_wait_sessions status variable: server-status-variables.
                                                             (line 1132)
* Rpl_semi_sync_master_yes_tx status variable: server-status-variables.
                                                             (line 1139)
* rpl_semi_sync_slave_enabled status variable: server-status-variables.
                                                             (line 1156)
* rpl_semi_sync_slave_enabled system variable: server-system-variables.
                                                             (line 3753)
* Rpl_semi_sync_slave_status status variable: server-status-variables.
                                                             (line 1147)
* rpl_semi_sync_slave_trace_level system variable: server-system-variables.
                                                             (line 3762)
* RPM file:                              linux-rpm.          (line    6)
* rpm option, mysql_install_db:          mysql-install-db.   (line   56)
* RPM Package Manager:                   linux-rpm.          (line    6)
* RTRIM():                               string-functions.   (line  567)
* RTS-threads:                           rts-threads.        (line    6)
* Ruby API:                              apis-ruby.          (line   11)
* running configure after prior invocation: compilation-problems.
                                                             (line   15)
* running, ANSI mode:                    ansi-mode.          (line    6)
* running, batch mode:                   batch-mode.         (line    6)
* running, multiple servers:             multiple-servers.   (line   12)
* running, queries:                      entering-queries.   (line    6)
* safe-mode option, mysqld:              server-options.     (line 1292)
* safe-recover option, myisamchk:        myisamchk-repair-options.
                                                             (line   84)
* safe-show-database option, mysqld <1>: privileges-options. (line   64)
* safe-show-database option, mysqld:     server-options.     (line 1301)
* safe-updates option:                   safe-updates.       (line    6)
* safe-updates option, mysql:            mysql-command-options.
                                                             (line  393)
* safe-user-create option, mysqld <1>:   privileges-options. (line   74)
* safe-user-create option, mysqld:       server-options.     (line 1317)
* Sakila:                                history.            (line    6)
* SAVEPOINT:                             savepoint.          (line    6)
* Saving state, thread state:            general-thread-states.
                                                             (line  245)
* scale, arithmetic:                     precision-math.     (line   14)
* SCHEMA():                              information-functions.
                                                             (line  465)
* schema, altering:                      alter-database.     (line    6)
* schema, creating:                      create-database.    (line    6)
* schema, deleting:                      drop-database.      (line    6)
* SCHEMA_PRIVILEGES, INFORMATION_SCHEMA table: schema-privileges-table.
                                                             (line    6)
* SCHEMATA, INFORMATION_SCHEMA table:    schemata-table.     (line    6)
* script files:                          batch-mode.         (line    6)
* scripts <1>:                           mysqld-multi.       (line    6)
* scripts:                               mysqld-safe.        (line    6)
* scripts, mysql_install_db:             mysql-install-db-problems.
                                                             (line    6)
* scripts, mysqlbug:                     bug-reports.        (line  334)
* scripts, SQL:                          mysql.              (line   14)
* search option, mysqlbackup:            mysqlbackup.        (line  128)
* Searching rows for update, thread state: general-thread-states.
                                                             (line  252)
* searching, and case sensitivity:       case-sensitivity.   (line    6)
* searching, full-text:                  fulltext-search.    (line   15)
* searching, MySQL Web pages:            bug-reports.        (line    6)
* searching, two keys:                   searching-on-two-keys.
                                                             (line    6)
* SEC_TO_TIME():                         date-and-time-functions.
                                                             (line  771)
* SECOND():                              date-and-time-functions.
                                                             (line  764)
* secondary index, InnoDB:               innodb-index-types. (line    6)
* secure-auth option, mysql:             mysql-command-options.
                                                             (line  401)
* secure-auth option, mysqld <1>:        privileges-options. (line   89)
* secure-auth option, mysqld:            server-options.     (line 1339)
* secure-backup-file-priv option, mysqld <1>: privileges-options.
                                                             (line   98)
* secure-backup-file-priv option, mysqld: server-options.    (line 1356)
* secure-file-priv option, mysqld <1>:   privileges-options. (line  117)
* secure-file-priv option, mysqld:       server-options.     (line 1375)
* secure_auth system variable:           server-system-variables.
                                                             (line 3769)
* secure_backup_file_priv system variable: server-system-variables.
                                                             (line 3795)
* secure_file_priv system variable:      server-system-variables.
                                                             (line 3803)
* security system:                       privilege-system.   (line   16)
* security, against attackers:           security-against-attack.
                                                             (line    6)
* SELECT INTO:                           select-into-statement.
                                                             (line    6)
* SELECT INTO TABLE:                     ansi-diff-select-into-table.
                                                             (line    6)
* SELECT speed:                          select-speed.       (line    6)
* SELECT, LIMIT:                         select.             (line   12)
* SELECT, optimizing <1>:                explain.            (line    6)
* SELECT, optimizing:                    using-explain.      (line    6)
* SELECT, Query Cache:                   query-cache.        (line   13)
* select_limit variable:                 mysql-command-options.
                                                             (line  557)
* selecting, databases:                  creating-database.  (line    6)
* semi-consistent read, InnoDB:          innodb-parameters.  (line  367)
* semisynchronous replication:           replication-semisync.
                                                             (line   12)
* semisynchronous replication, administrative interface: replication-semisync-interface.
                                                             (line    6)
* semisynchronous replication, configuration: replication-semisync-installation.
                                                             (line    6)
* semisynchronous replication, installation: replication-semisync-installation.
                                                             (line    6)
* semisynchronous replication, monitoring: replication-semisync-monitoring.
                                                             (line    6)
* Sending binlog event to slave, thread state: master-thread-states.
                                                             (line   11)
* SEQUENCE:                              example-auto-increment.
                                                             (line    6)
* sequence emulation:                    information-functions.
                                                             (line  397)
* sequences:                             example-auto-increment.
                                                             (line    6)
* SERIAL:                                numeric-type-overview.
                                                             (line    6)
* SERIAL DEFAULT VALUE:                  data-type-defaults. (line   75)
* SERIALIZABLE, transaction isolation level: set-transaction.
                                                             (line  126)
* server administration:                 mysqladmin.         (line    6)
* server variables <1>:                  show-variables.     (line    6)
* server variables:                      server-system-variables.
                                                             (line    6)
* server, connecting <1>:                connecting.         (line    6)
* server, connecting:                    connecting-disconnecting.
                                                             (line    6)
* server, debugging:                     debugging-server.   (line   16)
* server, disconnecting:                 connecting-disconnecting.
                                                             (line    6)
* server, logs:                          server-logs.        (line   15)
* server, restart:                       unix-post-installation.
                                                             (line  178)
* server, shutdown:                      unix-post-installation.
                                                             (line  170)
* server, signal handling:               server-signal-response.
                                                             (line    6)
* server, starting:                      unix-post-installation.
                                                             (line   48)
* server, starting and stopping:         automatic-start.    (line    6)
* server, starting problems:             starting-server.    (line    6)
* server-id option, mysqlbinlog:         mysqlbinlog.        (line  289)
* server-id option, mysqld:              replication-options.
                                                             (line   21)
* server-side cursor restrictions:       cursor-restrictions.
                                                             (line    6)
* server_id system variable:             server-system-variables.
                                                             (line 3825)
* servers, multiple:                     multiple-servers.   (line   12)
* service-startup-timeout option, mysql.server: mysql-server.
                                                             (line   49)
* session server variables:              server-session-variables.
                                                             (line    6)
* session system variables:              server-session-variables.
                                                             (line    6)
* session variable, autocommit:          server-session-variables.
                                                             (line   58)
* session variable, backup_wait_timeout: server-session-variables.
                                                             (line   70)
* session variable, big_tables:          server-session-variables.
                                                             (line   78)
* session variable, error_count:         server-session-variables.
                                                             (line   93)
* session variable, foreign_key_checks:  server-session-variables.
                                                             (line   99)
* session variable, identity:            server-session-variables.
                                                             (line  120)
* session variable, insert_id:           server-session-variables.
                                                             (line  127)
* session variable, last_insert_id:      server-session-variables.
                                                             (line  133)
* session variable, profiling:           server-session-variables.
                                                             (line  141)
* session variable, profiling_history_size: server-session-variables.
                                                             (line  149)
* session variable, rand_seed1:          server-session-variables.
                                                             (line  157)
* session variable, rand_seed2:          server-session-variables.
                                                             (line  171)
* session variable, sql_auto_is_null:    server-session-variables.
                                                             (line  175)
* session variable, sql_big_selects:     server-session-variables.
                                                             (line  185)
* session variable, sql_buffer_result:   server-session-variables.
                                                             (line  198)
* session variable, sql_log_bin:         server-session-variables.
                                                             (line  206)
* session variable, sql_log_off:         server-session-variables.
                                                             (line  212)
* session variable, sql_log_update:      server-session-variables.
                                                             (line  218)
* session variable, sql_notes:           server-session-variables.
                                                             (line  222)
* session variable, sql_quote_show_create: server-session-variables.
                                                             (line  230)
* session variable, sql_safe_updates:    server-session-variables.
                                                             (line  239)
* session variable, sql_warnings:        server-session-variables.
                                                             (line  248)
* session variable, timestamp:           server-session-variables.
                                                             (line  254)
* session variable, unique_checks:       server-session-variables.
                                                             (line  268)
* session variable, warning_count:       server-session-variables.
                                                             (line  281)
* session variables, and replication:    replication-features-variables.
                                                             (line    6)
* session variables, server:             server-session-variables.
                                                             (line    6)
* session variables, system:             server-session-variables.
                                                             (line    6)
* SESSION_STATUS, INFORMATION_SCHEMA table: status-table.    (line    6)
* SESSION_USER():                        information-functions.
                                                             (line  469)
* SESSION_VARIABLES, INFORMATION_SCHEMA table: variables-table.
                                                             (line    6)
* SET <1>:                               set-statement.      (line    6)
* SET:                                   set-option.         (line    6)
* SET data type <1>:                     set.                (line    6)
* SET data type:                         string-type-overview.
                                                             (line  248)
* SET GLOBAL SQL_SLAVE_SKIP_COUNTER:     set-global-sql-slave-skip-counter.
                                                             (line    6)
* SET OPTION:                            set-option.         (line    6)
* Set option, thread command:            thread-commands.    (line  111)
* SET PASSWORD:                          set-password.       (line    6)
* SET PASSWORD statement:                passwords.          (line    6)
* SET sql_log_bin:                       set-sql-log-bin.    (line    6)
* SET TRANSACTION:                       set-transaction.    (line    6)
* SET, CHARACTER SET <1>:                set-option.         (line  168)
* SET, CHARACTER SET:                    charset-connection. (line    6)
* SET, NAMES <1>:                        set-option.         (line  184)
* SET, NAMES <2>:                        charset-applications.
                                                             (line    6)
* SET, NAMES:                            charset-connection. (line    6)
* SET, ONE_SHOT:                         set-option.         (line  200)
* SET, size:                             storage-requirements.
                                                             (line  169)
* set-auto-increment[ option, myisamchk: myisamchk-other-options.
                                                             (line   32)
* set-character-set option, myisamchk:   myisamchk-repair-options.
                                                             (line   97)
* set-charset option, mysqlbinlog:       mysqlbinlog.        (line  294)
* set-charset option, mysqldump:         mysqldump.          (line  705)
* set-collation option, myisamchk:       myisamchk-repair-options.
                                                             (line  102)
* set-random-seed option, mysqlslap:     mysqlslap.          (line  433)
* setting passwords:                     set-password.       (line    6)
* setting program variables:             program-variables.  (line    6)
* setting, passwords:                    passwords.          (line    6)
* setup, post-installation:              post-installation.  (line   12)
* setup, thread state:                   general-thread-states.
                                                             (line  263)
* SHA():                                 encryption-functions.
                                                             (line  277)
* SHA1():                                encryption-functions.
                                                             (line  277)
* SHA2():                                encryption-functions.
                                                             (line  293)
* shared-memory option, mysqld:          server-options.     (line 1396)
* shared-memory-base-name option:        connecting.         (line  183)
* shared-memory-base-name option, mysqld: server-options.    (line 1401)
* shared-memory-base-name option, mysqlslap: mysqlslap.      (line  393)
* shared_memory system variable:         server-system-variables.
                                                             (line 3846)
* shared_memory_base_name system variable: server-system-variables.
                                                             (line 3856)
* shell syntax <1>:                      mem-conventions.    (line  102)
* shell syntax:                          manual-conventions. (line  112)
* short-form option, mysqlbinlog:        mysqlbinlog.        (line  299)
* SHOW AUTHORS <1>:                      show-authors.       (line    6)
* SHOW AUTHORS:                          show.               (line   49)
* SHOW BINARY LOGS:                      show-binary-logs.   (line    6)
* SHOW BINLOG EVENTS <1>:                show-binlog-events. (line    6)
* SHOW BINLOG EVENTS:                    show.               (line   94)
* SHOW CHARACTER SET <1>:                show-character-set. (line    6)
* SHOW CHARACTER SET:                    show.               (line   49)
* SHOW COLLATION <1>:                    show-collation.     (line    6)
* SHOW COLLATION:                        show.               (line   49)
* SHOW COLUMNS <1>:                      show-columns.       (line    6)
* SHOW COLUMNS:                          show.               (line   49)
* SHOW CONTRIBUTORS <1>:                 show-contributors.  (line    6)
* SHOW CONTRIBUTORS:                     show.               (line   49)
* SHOW CREATE DATABASE <1>:              show-create-database.
                                                             (line    6)
* SHOW CREATE DATABASE:                  show.               (line   49)
* SHOW CREATE EVENT:                     show.               (line   49)
* SHOW CREATE FUNCTION <1>:              show-create-function.
                                                             (line    6)
* SHOW CREATE FUNCTION:                  show.               (line   49)
* SHOW CREATE PROCEDURE <1>:             show-create-procedure.
                                                             (line    6)
* SHOW CREATE PROCEDURE:                 show.               (line   49)
* SHOW CREATE SCHEMA <1>:                show-create-database.
                                                             (line    6)
* SHOW CREATE SCHEMA:                    show.               (line   49)
* SHOW CREATE TABLE <1>:                 show-create-table.  (line    6)
* SHOW CREATE TABLE:                     show.               (line   49)
* SHOW CREATE TRIGGER <1>:               show-create-trigger.
                                                             (line    6)
* SHOW CREATE TRIGGER:                   show.               (line   49)
* SHOW CREATE VIEW <1>:                  show-create-view.   (line    6)
* SHOW CREATE VIEW:                      show.               (line   49)
* SHOW DATABASES <1>:                    show-databases.     (line    6)
* SHOW DATABASES:                        show.               (line   49)
* SHOW ENGINE <1>:                       show-engine.        (line    6)
* SHOW ENGINE:                           show.               (line   49)
* SHOW ENGINE INNODB STATUS:             show-engine.        (line    6)
* SHOW ENGINES <1>:                      show-engines.       (line    6)
* SHOW ENGINES:                          show.               (line   49)
* SHOW ERRORS <1>:                       show-errors.        (line    6)
* SHOW ERRORS:                           show.               (line   49)
* SHOW EVENTS:                           show.               (line   49)
* SHOW extensions:                       extended-show.      (line    6)
* SHOW FIELDS <1>:                       show-columns.       (line   92)
* SHOW FIELDS:                           show.               (line   49)
* SHOW FUNCTION CODE <1>:                show-function-code. (line    6)
* SHOW FUNCTION CODE:                    show.               (line   49)
* SHOW FUNCTION STATUS <1>:              show-function-status.
                                                             (line    6)
* SHOW FUNCTION STATUS:                  show.               (line   49)
* SHOW GRANTS <1>:                       show-grants.        (line    6)
* SHOW GRANTS:                           show.               (line   49)
* SHOW INDEX <1>:                        show-index.         (line    6)
* SHOW INDEX:                            show.               (line   49)
* SHOW KEYS <1>:                         show-index.         (line    6)
* SHOW KEYS:                             show.               (line   49)
* SHOW MASTER LOGS <1>:                  show-binary-logs.   (line    6)
* SHOW MASTER LOGS:                      show.               (line   94)
* SHOW MASTER STATUS <1>:                show-master-status. (line    6)
* SHOW MASTER STATUS:                    show.               (line   94)
* SHOW OPEN TABLES <1>:                  show-open-tables.   (line    6)
* SHOW OPEN TABLES:                      show.               (line   49)
* SHOW PLUGINS <1>:                      show-plugins.       (line    6)
* SHOW PLUGINS:                          show.               (line   49)
* SHOW PRIVILEGES <1>:                   show-privileges.    (line    6)
* SHOW PRIVILEGES:                       show.               (line   49)
* SHOW PROCEDURE CODE <1>:               show-procedure-code.
                                                             (line    6)
* SHOW PROCEDURE CODE:                   show.               (line   49)
* SHOW PROCEDURE STATUS <1>:             show-procedure-status.
                                                             (line    6)
* SHOW PROCEDURE STATUS:                 show.               (line   49)
* SHOW PROCESSLIST <1>:                  show-processlist.   (line    6)
* SHOW PROCESSLIST:                      show.               (line   49)
* SHOW PROFILE <1>:                      show-profiles.      (line    6)
* SHOW PROFILE <2>:                      show-profile.       (line    6)
* SHOW PROFILE:                          show.               (line   49)
* SHOW PROFILES <1>:                     show-profiles.      (line    6)
* SHOW PROFILES:                         show.               (line   49)
* SHOW SCHEDULER STATUS:                 show.               (line   49)
* SHOW SCHEMAS <1>:                      show-databases.     (line    6)
* SHOW SCHEMAS:                          show.               (line   49)
* SHOW SLAVE HOSTS <1>:                  show-slave-hosts.   (line    6)
* SHOW SLAVE HOSTS:                      show.               (line   94)
* SHOW SLAVE STATUS <1>:                 show-slave-status.  (line    6)
* SHOW SLAVE STATUS:                     show.               (line   94)
* SHOW STATUS:                           show.               (line   49)
* SHOW STORAGE ENGINES:                  show-engines.       (line    6)
* SHOW TABLE STATUS:                     show.               (line   49)
* SHOW TABLES <1>:                       show-tables.        (line    6)
* SHOW TABLES:                           show.               (line   49)
* SHOW TRIGGERS <1>:                     show-triggers.      (line    6)
* SHOW TRIGGERS:                         show.               (line   49)
* SHOW VARIABLES:                        show.               (line   49)
* SHOW WARNINGS <1>:                     show-warnings.      (line    6)
* SHOW WARNINGS:                         show.               (line   49)
* SHOW with WHERE <1>:                   extended-show.      (line    6)
* SHOW with WHERE:                       information-schema. (line   39)
* show-slave-auth-info option, mysqld:   replication-options-slave.
                                                             (line  564)
* show-table-type option, mysqlshow:     mysqlshow.          (line  175)
* show-warnings option, mysql:           mysql-command-options.
                                                             (line  413)
* showing, database information:         mysqlshow.          (line    6)
* Shutdown, thread command:              thread-commands.    (line  116)
* shutdown_timeout variable:             mysqladmin.         (line  442)
* shutting down, the server:             unix-post-installation.
                                                             (line  170)
* sigint-ignore option, mysql:           mysql-command-options.
                                                             (line  418)
* SIGN():                                mathematical-functions.
                                                             (line  514)
* SIGNAL:                                signal.             (line   11)
* signal restrictions:                   signal-restrictions.
                                                             (line    6)
* signals, server response:              server-signal-response.
                                                             (line    6)
* silent column changes:                 silent-column-changes.
                                                             (line    6)
* silent option, myisamchk:              myisamchk-general-options.
                                                             (line   27)
* silent option, myisampack:             myisampack.         (line   95)
* silent option, mysql:                  mysql-command-options.
                                                             (line  422)
* silent option, mysqladmin:             mysqladmin.         (line  389)
* silent option, mysqlcheck:             mysqlcheck.         (line  331)
* silent option, mysqld_multi:           mysqld-multi.       (line  126)
* silent option, mysqlimport:            mysqlimport.        (line  253)
* silent option, mysqlslap:              mysqlslap.          (line  437)
* silent option, perror:                 perror.             (line   39)
* silent option, resolveip:              resolveip.          (line   20)
* SIN():                                 mathematical-functions.
                                                             (line  526)
* single quote (\'):                     string-syntax.      (line   56)
* single-transaction option, mysqldump:  mysqldump.          (line  711)
* size of tables:                        full-table.         (line    6)
* sizes, display:                        data-types.         (line   31)
* skip-column-names option, mysql:       mysql-command-options.
                                                             (line  431)
* skip-comments option, mysqldump:       mysqldump.          (line  741)
* skip-concurrent-insert option, mysqld: server-options.     (line 1407)
* skip-external-locking option, mysqld:  server-options.     (line 1413)
* skip-grant-tables option, mysqld <1>:  privileges-options. (line  138)
* skip-grant-tables option, mysqld:      server-options.     (line 1421)
* skip-host-cache option, mysqld:        server-options.     (line 1438)
* skip-innodb option, mysqld:            server-options.     (line 1444)
* skip-kill-mysqld option, mysqld_safe:  mysqld-safe.        (line  198)
* skip-line-numbers option, mysql:       mysql-command-options.
                                                             (line  436)
* skip-name-resolve option, mysql_install_db: mysql-install-db.
                                                             (line   61)
* skip-name-resolve option, mysqld <1>:  privileges-options. (line  149)
* skip-name-resolve option, mysqld:      server-options.     (line 1450)
* skip-networking option, mysqld <1>:    privileges-options. (line  154)
* skip-networking option, mysqld:        server-options.     (line 1457)
* skip-opt option, mysqldump:            mysqldump.          (line  745)
* skip-safemalloc option, mysqld:        server-options.     (line 1503)
* skip-show-database option, mysqld <1>: privileges-options. (line  159)
* skip-show-database option, mysqld:     server-options.     (line 1515)
* skip-slave-start option, mysqld:       replication-options-slave.
                                                             (line  571)
* skip-stack-trace option, mysqld:       server-options.     (line 1535)
* skip-symbolic-links option, mysqld:    server-options.     (line 1481)
* skip-syslog option, mysqld_safe:       mysqld-safe.        (line  208)
* skip-thread-priority option, mysqld:   server-options.     (line 1547)
* skip-use-db option, mysql_find_rows:   mysql-find-rows.    (line   43)
* skip_external_locking system variable: server-system-variables.
                                                             (line 3868)
* skip_networking system variable:       server-system-variables.
                                                             (line 3873)
* skip_show_database system variable:    server-system-variables.
                                                             (line 3882)
* slave option, mysqlslap:               mysqlslap.          (line  441)
* slave-load-tmpdir option, mysqld:      replication-options-slave.
                                                             (line  583)
* slave-net-timeout option, mysqld:      replication-options-slave.
                                                             (line  605)
* slave-skip-errors option, mysqld:      replication-options-slave.
                                                             (line  616)
* slave_compressed_protocol option, mysqld: replication-options-slave.
                                                             (line  577)
* slave_compressed_protocol system variable: replication-options-slave.
                                                             (line  868)
* slave_exec_mode system variable:       replication-options-slave.
                                                             (line  885)
* slave_load_tmpdir system variable:     replication-options-slave.
                                                             (line  905)
* slave_net_timeout system variable:     replication-options-slave.
                                                             (line  922)
* slave_skip_errors system variable:     replication-options-slave.
                                                             (line  942)
* slave_transaction_retries system variable: replication-options-slave.
                                                             (line  959)
* sleep option, mysqladmin:              mysqladmin.         (line  393)
* SLEEP():                               miscellaneous-functions.
                                                             (line  193)
* Sleep, thread command:                 thread-commands.    (line  120)
* slow queries:                          mysqladmin.         (line  197)
* slow query log:                        slow-query-log.     (line    6)
* slow query log, and replication:       replication-features-logging.
                                                             (line    6)
* slow-query-log option, mysqld:         server-options.     (line 1558)
* slow_launch_time system variable:      server-system-variables.
                                                             (line 3896)
* slow_query_log system variable:        server-system-variables.
                                                             (line 3912)
* slow_query_log_file system variable:   server-system-variables.
                                                             (line 3922)
* SMALLINT data type:                    numeric-type-overview.
                                                             (line  108)
* snapshots option, mysqlbackup:         mysqlbackup.        (line  137)
* socket location, changing:             configure-options.  (line  342)
* socket option:                         connecting.         (line  192)
* socket option, mysql:                  mysql-command-options.
                                                             (line  442)
* socket option, mysql_config:           mysql-config.       (line   48)
* socket option, mysql_convert_table_format: mysql-convert-table-format.
                                                             (line   50)
* socket option, mysql_setpermission:    mysql-setpermission.
                                                             (line   51)
* socket option, mysqladmin:             mysqladmin.         (line  400)
* socket option, mysqlbinlog:            mysqlbinlog.        (line  304)
* socket option, mysqlcheck:             mysqlcheck.         (line  335)
* socket option, mysqld:                 server-options.     (line 1577)
* socket option, mysqld_safe:            mysqld-safe.        (line  203)
* socket option, mysqldump:              mysqldump.          (line  749)
* socket option, mysqlhotcopy:           mysqlhotcopy.       (line  162)
* socket option, mysqlimport:            mysqlimport.        (line  257)
* socket option, mysqlshow:              mysqlshow.          (line  180)
* socket option, mysqlslap:              mysqlslap.          (line  449)
* socket system variable:                server-system-variables.
                                                             (line 3940)
* Solaris installation problems:         solaris.            (line   11)
* Solaris troubleshooting:               compilation-problems.
                                                             (line  104)
* Solaris x86_64 issues:                 innodb-tuning.      (line    6)
* Solaris, installation:                 solaris-installation.
                                                             (line    6)
* SOME:                                  any-in-some-subqueries.
                                                             (line    6)
* sort-index option, myisamchk:          myisamchk-other-options.
                                                             (line   40)
* sort-records option, myisamchk:        myisamchk-other-options.
                                                             (line   45)
* sort-recover option, myisamchk:        myisamchk-repair-options.
                                                             (line  108)
* sort_buffer_size myisamchk variable:   myisamchk-general-options.
                                                             (line   53)
* sort_buffer_size system variable:      server-system-variables.
                                                             (line 3963)
* sort_key_blocks myisamchk variable:    myisamchk-general-options.
                                                             (line   53)
* Sorting for group, thread state:       general-thread-states.
                                                             (line  268)
* Sorting for order, thread state:       general-thread-states.
                                                             (line  272)
* Sorting index, thread state:           general-thread-states.
                                                             (line  276)
* Sorting result, thread state:          general-thread-states.
                                                             (line  281)
* sorting, character sets:               charset-configuration.
                                                             (line   10)
* sorting, data:                         sorting-rows.       (line    6)
* sorting, grant tables <1>:             request-access.     (line   52)
* sorting, grant tables:                 connection-access.  (line  120)
* sorting, table rows:                   sorting-rows.       (line    6)
* SOUNDEX():                             string-functions.   (line  576)
* SOUNDS LIKE:                           string-functions.   (line  615)
* source (mysql client command) <1>:     batch-commands.     (line    6)
* source (mysql client command):         batch-mode.         (line   90)
* source command, mysql:                 mysql-commands.     (line  188)
* source distribution, installing:       installing-source.  (line   16)
* source distributions, on Linux:        source-notes-linux. (line    6)
* SPACE():                               string-functions.   (line  619)
* spassword option, mysqlaccess:         mysqlaccess.        (line  131)
* Spatial Extensions in MySQL:           gis-introduction.   (line    6)
* speed, compiling:                      compile-and-link-options.
                                                             (line    6)
* speed, increasing with replication:    replication.        (line   13)
* speed, inserting:                      insert-speed.       (line    6)
* speed, linking:                        compile-and-link-options.
                                                             (line    6)
* speed, of queries <1>:                 select-speed.       (line    6)
* speed, of queries:                     query-speed.        (line   36)
* sporadic-binlog-dump-fail option, mysqld: replication-options-binary-log.
                                                             (line  283)
* SQL mode:                              server-sql-mode.    (line    6)
* SQL mode, ALLOW_INVALID_DATES:         server-sql-mode.    (line   87)
* SQL mode, ANSI:                        server-sql-mode.    (line   55)
* SQL mode, ANSI_QUOTES:                 server-sql-mode.    (line  105)
* SQL mode, DB2:                         server-sql-mode.    (line  447)
* SQL mode, ERROR_FOR_DIVISION_BY_ZERO:  server-sql-mode.    (line  113)
* SQL mode, HIGH_NOT_PRECEDENCE:         server-sql-mode.    (line  122)
* SQL mode, IGNORE_SPACE:                server-sql-mode.    (line  137)
* SQL mode, MAXDB:                       server-sql-mode.    (line  452)
* SQL mode, MSSQL:                       server-sql-mode.    (line  458)
* SQL mode, MYSQL323:                    server-sql-mode.    (line  463)
* SQL mode, MYSQL40:                     server-sql-mode.    (line  467)
* SQL mode, NO_AUTO_CREATE_USER:         server-sql-mode.    (line  162)
* SQL mode, NO_AUTO_VALUE_ON_ZERO:       server-sql-mode.    (line  168)
* SQL mode, NO_BACKSLASH_ESCAPES:        server-sql-mode.    (line  187)
* SQL mode, NO_DIR_IN_CREATE:            server-sql-mode.    (line  193)
* SQL mode, NO_ENGINE_SUBSTITUTION:      server-sql-mode.    (line  199)
* SQL mode, NO_FIELD_OPTIONS:            server-sql-mode.    (line  218)
* SQL mode, NO_KEY_OPTIONS:              server-sql-mode.    (line  224)
* SQL mode, NO_TABLE_OPTIONS:            server-sql-mode.    (line  230)
* SQL mode, NO_UNSIGNED_SUBTRACTION:     server-sql-mode.    (line  236)
* SQL mode, NO_ZERO_DATE:                server-sql-mode.    (line  283)
* SQL mode, NO_ZERO_IN_DATE:             server-sql-mode.    (line  289)
* SQL mode, ONLY_FULL_GROUP_BY <1>:      group-by-hidden-columns.
                                                             (line    6)
* SQL mode, ONLY_FULL_GROUP_BY:          server-sql-mode.    (line  298)
* SQL mode, ORACLE:                      server-sql-mode.    (line  471)
* SQL mode, PAD_CHAR_TO_FULL_LENGTH:     server-sql-mode.    (line  310)
* SQL mode, PIPES_AS_CONCAT:             server-sql-mode.    (line  347)
* SQL mode, POSTGRESQL:                  server-sql-mode.    (line  477)
* SQL mode, REAL_AS_FLOAT:               server-sql-mode.    (line  352)
* SQL mode, strict:                      server-sql-mode.    (line   82)
* SQL mode, STRICT_ALL_TABLES:           server-sql-mode.    (line  358)
* SQL mode, STRICT_TRANS_TABLES:         server-sql-mode.    (line   60)
* SQL mode, TRADITIONAL:                 server-sql-mode.    (line   68)
* SQL scripts:                           mysql.              (line   14)
* SQL statements, replication masters:   replication-master-sql.
                                                             (line   12)
* SQL statements, replication slaves:    replication-slave-sql.
                                                             (line   15)
* SQL, defined:                          what-is-mysql.      (line   42)
* SQL-92, extensions to:                 compatibility.      (line   15)
* sql-mode option, mysqld:               server-options.     (line 1597)
* sql_auto_is_null session variable:     server-session-variables.
                                                             (line  175)
* SQL_BIG_RESULT:                        select.             (line  483)
* sql_big_selects session variable:      server-session-variables.
                                                             (line  185)
* SQL_BUFFER_RESULT:                     select.             (line  489)
* sql_buffer_result session variable:    server-session-variables.
                                                             (line  198)
* SQL_CACHE <1>:                         select.             (line  506)
* SQL_CACHE:                             query-cache-in-select.
                                                             (line    9)
* SQL_CALC_FOUND_ROWS:                   select.             (line  501)
* sql_log_bin session variable:          server-session-variables.
                                                             (line  206)
* sql_log_off session variable:          server-session-variables.
                                                             (line  212)
* sql_log_update session variable:       server-session-variables.
                                                             (line  218)
* sql_mode system variable:              server-system-variables.
                                                             (line 3993)
* SQL_NO_CACHE <1>:                      select.             (line  506)
* SQL_NO_CACHE:                          query-cache-in-select.
                                                             (line    9)
* sql_notes session variable:            server-session-variables.
                                                             (line  222)
* sql_quote_show_create session variable: server-session-variables.
                                                             (line  230)
* sql_safe_updates session variable:     server-session-variables.
                                                             (line  239)
* sql_select_limit system variable:      server-system-variables.
                                                             (line 4032)
* SQL_SLAVE_SKIP_COUNTER:                set-global-sql-slave-skip-counter.
                                                             (line    6)
* sql_slave_skip_counter system variable: replication-options-slave.
                                                             (line  649)
* SQL_SMALL_RESULT:                      select.             (line  496)
* sql_warnings session variable:         server-session-variables.
                                                             (line  248)
* sql_yacc.cc problems:                  compilation-problems.
                                                             (line   38)
* SQRT():                                mathematical-functions.
                                                             (line  535)
* square brackets:                       data-types.         (line   40)
* srcdir option, mysql_install_db:       mysql-install-db.   (line   66)
* SRID():                                general-geometry-property-functions.
                                                             (line   51)
* SSH:                                   windows-and-ssh.    (line    6)
* SSL:                                   secure-using-ssl.   (line    6)
* SSL and X509 Basics:                   secure-connections. (line   13)
* SSL command options:                   ssl-options.        (line    6)
* ssl option:                            ssl-options.        (line   31)
* SSL options:                           connecting.         (line  205)
* SSL options, mysql:                    mysql-command-options.
                                                             (line  447)
* SSL options, mysqladmin:               mysqladmin.         (line  405)
* SSL options, mysqlcheck:               mysqlcheck.         (line  340)
* SSL options, mysqld <1>:               privileges-options. (line  169)
* SSL options, mysqld:                   server-options.     (line 1465)
* SSL options, mysqldump:                mysqldump.          (line  754)
* SSL options, mysqlimport:              mysqlimport.        (line  262)
* SSL options, mysqlshow:                mysqlshow.          (line  185)
* SSL options, mysqlslap:                mysqlslap.          (line  454)
* SSL related options:                   grant.              (line  443)
* ssl-ca option:                         ssl-options.        (line   60)
* ssl-capath option:                     ssl-options.        (line   64)
* ssl-cert option:                       ssl-options.        (line   69)
* ssl-cipher option:                     ssl-options.        (line   74)
* ssl-key option:                        ssl-options.        (line   93)
* ssl-verify-server-cert option:         ssl-options.        (line   98)
* ssl_ca system variable:                server-system-variables.
                                                             (line 4058)
* ssl_capath system variable:            server-system-variables.
                                                             (line 4073)
* ssl_cert system variable:              server-system-variables.
                                                             (line 4089)
* ssl_cipher system variable:            server-system-variables.
                                                             (line 4105)
* ssl_key system variable:               server-system-variables.
                                                             (line 4120)
* standalone option, mysqld:             server-options.     (line 1471)
* Standard Monitor, InnoDB:              innodb-monitors.    (line   12)
* Standard SQL, differences from <1>:    grant.              (line  546)
* Standard SQL, differences from:        differences-from-ansi.
                                                             (line   15)
* Standard SQL, extensions to <1>:       extensions-to-ansi. (line    6)
* Standard SQL, extensions to:           compatibility.      (line   15)
* standards compatibility:               compatibility.      (line   15)
* START SLAVE:                           start-slave.        (line    6)
* START TRANSACTION:                     commit.             (line    6)
* START, XA transactions:                xa-statements.      (line    6)
* start-datetime option, mysqlbinlog:    mysqlbinlog.        (line  309)
* start-position option, mysqlbinlog:    mysqlbinlog.        (line  323)
* start_row option, mysql_find_rows:     mysql-find-rows.    (line   47)
* Starting many servers:                 multiple-servers.   (line   12)
* starting, comments:                    ansi-diff-comments. (line    6)
* starting, mysqld:                      changing-mysql-user.
                                                             (line    6)
* starting, the server:                  unix-post-installation.
                                                             (line   48)
* starting, the server automatically:    automatic-start.    (line    6)
* StartPoint():                          linestring-property-functions.
                                                             (line   64)
* startup options, default:              option-files.       (line   11)
* startup parameters:                    server-parameters.  (line    6)
* startup parameters, mysql:             mysql-command-options.
                                                             (line    6)
* startup parameters, mysqladmin:        mysqladmin.         (line  232)
* startup parameters, tuning:            system-optimization.
                                                             (line    6)
* statefile option, comp_err:            comp-err.           (line   66)
* statement-based replication, advantages: replication-sbr-rbr.
                                                             (line   16)
* statement-based replication, disadvantages: replication-sbr-rbr.
                                                             (line   31)
* statement-based replication, unsafe statements: replication-sbr-rbr.
                                                             (line   31)
* statements, compound:                  sql-syntax-compound-statements.
                                                             (line   17)
* statements, GRANT:                     adding-users.       (line    6)
* statements, INSERT:                    adding-users.       (line  116)
* statements, replication masters:       replication-master-sql.
                                                             (line   12)
* statements, replication slaves:        replication-slave-sql.
                                                             (line   15)
* statically, compiling:                 configure-options.  (line  354)
* STATISTICS, INFORMATION_SCHEMA table:  statistics-table.   (line    6)
* Statistics, thread command:            thread-commands.    (line  124)
* statistics, thread state:              general-thread-states.
                                                             (line  286)
* stats option, myisam_ftdump:           myisam-ftdump.      (line   64)
* stats_method myisamchk variable:       myisamchk-general-options.
                                                             (line   53)
* status command, mysql:                 mysql-commands.     (line  194)
* status command, results:               mysqladmin.         (line  181)
* status option, mysqlshow:              mysqlshow.          (line  191)
* status variable, Rpl_semi_sync_master_clients: server-status-variables.
                                                             (line 1043)
* status variable, Rpl_semi_sync_master_net_avg_wait_time: server-status-variables.
                                                             (line 1050)
* status variable, Rpl_semi_sync_master_net_wait_time: server-status-variables.
                                                             (line 1057)
* status variable, Rpl_semi_sync_master_net_waits: server-status-variables.
                                                             (line 1064)
* status variable, Rpl_semi_sync_master_no_times: server-status-variables.
                                                             (line 1071)
* status variable, Rpl_semi_sync_master_no_tx: server-status-variables.
                                                             (line 1078)
* status variable, Rpl_semi_sync_master_status: server-status-variables.
                                                             (line 1086)
* status variable, Rpl_semi_sync_master_timefunc_failures: server-status-variables.
                                                             (line 1097)
* status variable, Rpl_semi_sync_master_tx_avg_wait_time: server-status-variables.
                                                             (line 1104)
* status variable, Rpl_semi_sync_master_tx_wait_time: server-status-variables.
                                                             (line 1111)
* status variable, Rpl_semi_sync_master_tx_waits: server-status-variables.
                                                             (line 1118)
* status variable, Rpl_semi_sync_master_wait_pos_backtraverse: server-status-variables.
                                                             (line 1125)
* status variable, Rpl_semi_sync_master_wait_sessions: server-status-variables.
                                                             (line 1132)
* status variable, Rpl_semi_sync_master_yes_tx: server-status-variables.
                                                             (line 1139)
* status variable, rpl_semi_sync_slave_enabled: server-status-variables.
                                                             (line 1156)
* status variable, Rpl_semi_sync_slave_status: server-status-variables.
                                                             (line 1147)
* status variables <1>:                  show-status.        (line    6)
* status variables:                      server-status-variables.
                                                             (line    6)
* status, tables:                        show-table-status.  (line    6)
* STD():                                 group-by-functions. (line  219)
* STDDEV():                              group-by-functions. (line  227)
* STDDEV_POP():                          group-by-functions. (line  235)
* STDDEV_SAMP():                         group-by-functions. (line  243)
* STOP SLAVE:                            stop-slave.         (line    6)
* stop-datetime option, mysqlbinlog:     mysqlbinlog.        (line  329)
* stop-position option, mysqlbinlog:     mysqlbinlog.        (line  336)
* stopping, the server:                  automatic-start.    (line    6)
* stopword list, user-defined:           fulltext-fine-tuning.
                                                             (line   40)
* storage engine, ARCHIVE:               archive-storage-engine.
                                                             (line    6)
* storage engines, choosing:             storage-engines.    (line   24)
* storage of data:                       design.             (line    6)
* storage requirements, data type:       storage-requirements.
                                                             (line    6)
* storage space, minimizing:             data-size.          (line    6)
* storage_engine system variable:        server-system-variables.
                                                             (line 4136)
* stored functions:                      stored-routines.    (line   13)
* stored functions, and INSERT DELAYED:  insert.             (line  229)
* stored procedures:                     stored-routines.    (line   13)
* stored procedures and triggers, defined: ansi-diff-triggers.
                                                             (line    6)
* stored programs <1>:                   stored-programs-views.
                                                             (line   15)
* stored programs:                       sql-syntax-compound-statements.
                                                             (line   17)
* stored routine restrictions:           stored-program-restrictions.
                                                             (line    6)
* stored routines, and replication:      replication-features-invoked.
                                                             (line    6)
* stored routines, LAST_INSERT_ID():     stored-routines-last-insert-id.
                                                             (line    6)
* stored routines, metadata:             stored-routines-metadata.
                                                             (line    6)
* storing row into queue, thread state:  delayed-insert-thread-states.
                                                             (line   39)
* STR_TO_DATE():                         date-and-time-functions.
                                                             (line  784)
* STRAIGHT_JOIN <1>:                     join.               (line    6)
* STRAIGHT_JOIN <2>:                     select.             (line  466)
* STRAIGHT_JOIN <3>:                     left-join-optimization.
                                                             (line   38)
* STRAIGHT_JOIN:                         using-explain.      (line   34)
* STRCMP():                              string-comparison-functions.
                                                             (line  144)
* strict SQL mode:                       server-sql-mode.    (line   82)
* STRICT_ALL_TABLES SQL mode:            server-sql-mode.    (line  358)
* STRICT_TRANS_TABLES SQL mode:          server-sql-mode.    (line   60)
* string collating:                      string-collating.   (line    6)
* string comparison functions:           string-comparison-functions.
                                                             (line    6)
* string comparisons, case sensitivity:  string-comparison-functions.
                                                             (line   15)
* string concatenation <1>:              string-functions.   (line  186)
* string concatenation:                  string-syntax.      (line   12)
* string functions:                      string-functions.   (line   11)
* string literal introducer <1>:         charset-literal.    (line   11)
* string literal introducer:             string-syntax.      (line   33)
* string replacement, replace utility:   replace-utility.    (line    6)
* string types:                          string-types.       (line   14)
* strings, defined:                      literals.           (line   15)
* strings, escaping characters:          literals.           (line   15)
* strings, non-delimited:                datetime.           (line  127)
* striping, defined:                     disk-issues.        (line   31)
* SUBDATE():                             date-and-time-functions.
                                                             (line  820)
* subpartitioning:                       partitioning-subpartitions.
                                                             (line    6)
* subpartitions:                         partitioning-subpartitions.
                                                             (line    6)
* subqueries:                            subqueries.         (line   20)
* subqueries, correlated:                correlated-subqueries.
                                                             (line    6)
* subqueries, errors:                    subquery-errors.    (line    6)
* subqueries, rewriting as joins:        rewriting-subqueries.
                                                             (line    6)
* subqueries, with ALL:                  all-subqueries.     (line    6)
* subqueries, with ANY, IN, SOME:        any-in-some-subqueries.
                                                             (line    6)
* subqueries, with EXISTS:               exists-and-not-exists-subqueries.
                                                             (line    6)
* subqueries, with NOT EXISTS:           exists-and-not-exists-subqueries.
                                                             (line    6)
* subqueries, with ROW:                  row-subqueries.     (line    6)
* subquery:                              subqueries.         (line   20)
* subquery optimization:                 in-subquery-optimization.
                                                             (line    6)
* subquery restrictions:                 subquery-restrictions.
                                                             (line    6)
* subselects:                            subqueries.         (line   20)
* SUBSTR():                              string-functions.   (line  626)
* SUBSTRING():                           string-functions.   (line  631)
* SUBSTRING_INDEX():                     string-functions.   (line  664)
* SUBTIME():                             date-and-time-functions.
                                                             (line  838)
* subtraction (-):                       arithmetic-functions.
                                                             (line   51)
* suffix option, mysqlhotcopy:           mysqlhotcopy.       (line  166)
* SUM():                                 group-by-functions. (line  250)
* SUM(DISTINCT):                         group-by-functions. (line  250)
* summary option, mysqlbackup:           mysqlbackup.        (line  141)
* superuser:                             default-privileges. (line    6)
* superuser option, mysqlaccess:         mysqlaccess.        (line  141)
* support, for operating systems:        which-os.           (line    6)
* suppression, default values:           constraint-invalid-data.
                                                             (line    6)
* Sybase compatibility:                  use.                (line   27)
* symbolic links <1>:                    windows-symbolic-links.
                                                             (line    6)
* symbolic links:                        symbolic-links.     (line   12)
* symbolic-links option, mysqld:         server-options.     (line 1481)
* symbols-file option, resolve_stack_dump: resolve-stack-dump.
                                                             (line   29)
* SymDifference():                       spatial-operators.  (line   32)
* sync_binlog system variable:           replication-options-binary-log.
                                                             (line  459)
* sync_frm system variable:              server-system-variables.
                                                             (line 4148)
* sync_master_info system variable:      replication-options-slave.
                                                             (line  782)
* sync_relay_log system variable:        replication-options-slave.
                                                             (line  809)
* sync_relay_log_info system variable:   replication-options-slave.
                                                             (line  840)
* syntax conventions:                    manual-conventions. (line    8)
* syntax, regular expression:            regexp.             (line    6)
* SYSDATE():                             date-and-time-functions.
                                                             (line  849)
* sysdate-is-now option, mysqld:         server-options.     (line 1635)
* syslog option, mysqld_safe:            mysqld-safe.        (line  208)
* syslog-tag option, mysqld_safe:        mysqld-safe.        (line  214)
* system command, mysql:                 mysql-commands.     (line  201)
* System lock, thread state:             general-thread-states.
                                                             (line  291)
* system optimization:                   system-optimization.
                                                             (line    6)
* system table, optimizer <1>:           select.             (line  472)
* system table, optimizer:               using-explain.      (line  129)
* system variable, auto_increment_increment: replication-options-master.
                                                             (line   21)
* system variable, auto_increment_offset: replication-options-master.
                                                             (line  215)
* system variable, automatic_sp_privileges: server-system-variables.
                                                             (line  525)
* system variable, back_log:             server-system-variables.
                                                             (line  623)
* system variable, backup_history_log:   server-system-variables.
                                                             (line  543)
* system variable, backup_history_log_file: server-system-variables.
                                                             (line  565)
* system variable, backup_progress_log:  server-system-variables.
                                                             (line  583)
* system variable, backup_progress_log_file: server-system-variables.
                                                             (line  605)
* system variable, backupdir:            server-system-variables.
                                                             (line  655)
* system variable, basedir:              server-system-variables.
                                                             (line  693)
* system variable, binlog_cache_size:    replication-options-binary-log.
                                                             (line  302)
* system variable, binlog_format:        replication-options-binary-log.
                                                             (line  339)
* system variable, bulk_insert_buffer_size: server-system-variables.
                                                             (line  710)
* system variable, character_set_client: server-system-variables.
                                                             (line  738)
* system variable, character_set_connection: server-system-variables.
                                                             (line  769)
* system variable, character_set_database: server-system-variables.
                                                             (line  780)
* system variable, character_set_filesystem: server-system-variables.
                                                             (line  796)
* system variable, character_set_results: server-system-variables.
                                                             (line  821)
* system variable, character_set_server: server-system-variables.
                                                             (line  831)
* system variable, character_set_system: server-system-variables.
                                                             (line  846)
* system variable, character_sets_dir:   server-system-variables.
                                                             (line  857)
* system variable, collation_connection: server-system-variables.
                                                             (line  872)
* system variable, collation_database:   server-system-variables.
                                                             (line  882)
* system variable, collation_server:     server-system-variables.
                                                             (line  898)
* system variable, completion_type:      server-system-variables.
                                                             (line  913)
* system variable, concurrent_insert:    server-system-variables.
                                                             (line  944)
* system variable, connect_timeout:      server-system-variables.
                                                             (line  980)
* system variable, datadir:              server-system-variables.
                                                             (line 1002)
* system variable, date_format:          server-system-variables.
                                                             (line 1018)
* system variable, datetime_format:      server-system-variables.
                                                             (line 1022)
* system variable, debug:                server-system-variables.
                                                             (line 1026)
* system variable, debug_sync:           server-system-variables.
                                                             (line 1072)
* system variable, default_week_format:  server-system-variables.
                                                             (line 1106)
* system variable, delay_key_write:      server-system-variables.
                                                             (line 1123)
* system variable, delayed_insert_limit: server-system-variables.
                                                             (line 1163)
* system variable, delayed_insert_timeout: server-system-variables.
                                                             (line 1189)
* system variable, delayed_queue_size:   server-system-variables.
                                                             (line 1207)
* system variable, div_precision_increment: server-system-variables.
                                                             (line 1234)
* system variable, event_scheduler:      server-system-variables.
                                                             (line 1268)
* system variable, expire_logs_days:     server-system-variables.
                                                             (line 1290)
* system variable, flush:                server-system-variables.
                                                             (line 1308)
* system variable, flush_time:           server-system-variables.
                                                             (line 1327)
* system variable, ft_boolean_syntax:    server-system-variables.
                                                             (line 1351)
* system variable, ft_max_word_len:      server-system-variables.
                                                             (line 1384)
* system variable, ft_min_word_len:      server-system-variables.
                                                             (line 1406)
* system variable, ft_query_expansion_limit: server-system-variables.
                                                             (line 1428)
* system variable, ft_stopword_file:     server-system-variables.
                                                             (line 1446)
* system variable, general_log:          server-system-variables.
                                                             (line 1471)
* system variable, general_log_file:     server-system-variables.
                                                             (line 1492)
* system variable, group_concat_max_len: server-system-variables.
                                                             (line 1510)
* system variable, have_compress:        server-system-variables.
                                                             (line 1534)
* system variable, have_crypt:           server-system-variables.
                                                             (line 1540)
* system variable, have_csv:             server-system-variables.
                                                             (line 1545)
* system variable, have_dynamic_loading: server-system-variables.
                                                             (line 1550)
* system variable, have_geometry:        server-system-variables.
                                                             (line 1555)
* system variable, have_innodb:          server-system-variables.
                                                             (line 1559)
* system variable, have_openssl:         server-system-variables.
                                                             (line 1564)
* system variable, have_partitioning:    server-system-variables.
                                                             (line 1568)
* system variable, have_query_cache:     server-system-variables.
                                                             (line 1572)
* system variable, have_rtree_keys:      server-system-variables.
                                                             (line 1577)
* system variable, have_ssl:             server-system-variables.
                                                             (line 1582)
* system variable, have_symlink:         server-system-variables.
                                                             (line 1587)
* system variable, hostname:             server-system-variables.
                                                             (line 1594)
* system variable, init_connect:         server-system-variables.
                                                             (line 1604)
* system variable, init_file:            server-system-variables.
                                                             (line 1642)
* system variable, init_slave:           replication-options-slave.
                                                             (line  741)
* system variable, interactive_timeout:  server-system-variables.
                                                             (line 1669)
* system variable, join_buffer_size:     server-system-variables.
                                                             (line 1690)
* system variable, join_cache_level:     server-system-variables.
                                                             (line 1727)
* system variable, keep_files_on_create: server-system-variables.
                                                             (line 1790)
* system variable, key_buffer_size:      server-system-variables.
                                                             (line 1818)
* system variable, key_cache_age_threshold: server-system-variables.
                                                             (line 1883)
* system variable, key_cache_block_size: server-system-variables.
                                                             (line 1909)
* system variable, key_cache_division_limit: server-system-variables.
                                                             (line 1927)
* system variable, language:             server-system-variables.
                                                             (line 1947)
* system variable, large_files_support:  server-system-variables.
                                                             (line 1963)
* system variable, large_page_size:      server-system-variables.
                                                             (line 1990)
* system variable, large_pages:          server-system-variables.
                                                             (line 1972)
* system variable, lc_time_names:        server-system-variables.
                                                             (line 2004)
* system variable, license:              server-system-variables.
                                                             (line 2020)
* system variable, local_infile:         server-system-variables.
                                                             (line 2031)
* system variable, locked_in_memory:     server-system-variables.
                                                             (line 2042)
* system variable, log:                  server-system-variables.
                                                             (line 2051)
* system variable, log_bin:              server-system-variables.
                                                             (line 2059)
* system variable, log_bin_trust_function_creators: server-system-variables.
                                                             (line 2067)
* system variable, log_error:            server-system-variables.
                                                             (line 2094)
* system variable, log_output:           server-system-variables.
                                                             (line 2109)
* system variable, log_queries_not_using_indexes: server-system-variables.
                                                             (line 2135)
* system variable, log_slave_updates:    server-system-variables.
                                                             (line 2152)
* system variable, log_slow_queries:     server-system-variables.
                                                             (line 2159)
* system variable, log_warnings:         server-system-variables.
                                                             (line 2179)
* system variable, long_query_time:      server-system-variables.
                                                             (line 2201)
* system variable, low_priority_updates: server-system-variables.
                                                             (line 2233)
* system variable, lower_case_file_system: server-system-variables.
                                                             (line 2254)
* system variable, lower_case_table_names: server-system-variables.
                                                             (line 2271)
* system variable, max_allowed_packet:   server-system-variables.
                                                             (line 2301)
* system variable, max_binlog_cache_size: replication-options-binary-log.
                                                             (line  402)
* system variable, max_binlog_size:      replication-options-binary-log.
                                                             (line  430)
* system variable, max_connect_errors:   server-system-variables.
                                                             (line 2343)
* system variable, max_connections:      server-system-variables.
                                                             (line 2369)
* system variable, max_delayed_threads:  server-system-variables.
                                                             (line 2400)
* system variable, max_error_count:      server-system-variables.
                                                             (line 2426)
* system variable, max_heap_table_size:  server-system-variables.
                                                             (line 2445)
* system variable, max_insert_delayed_threads: server-system-variables.
                                                             (line 2482)
* system variable, max_join_size:        server-system-variables.
                                                             (line 2492)
* system variable, max_length_for_sort_data: server-system-variables.
                                                             (line 2528)
* system variable, max_prepared_stmt_count: server-system-variables.
                                                             (line 2546)
* system variable, max_relay_log_size:   server-system-variables.
                                                             (line 2572)
* system variable, max_seeks_for_key:    server-system-variables.
                                                             (line 2598)
* system variable, max_sort_length:      server-system-variables.
                                                             (line 2627)
* system variable, max_sp_recursion_depth: server-system-variables.
                                                             (line 2646)
* system variable, max_tmp_tables:       server-system-variables.
                                                             (line 2671)
* system variable, max_user_connections: server-system-variables.
                                                             (line 2695)
* system variable, max_write_lock_count: server-system-variables.
                                                             (line 2718)
* system variable, min_examined_row_limit: server-system-variables.
                                                             (line 2742)
* system variable, myisam_data_pointer_size: server-system-variables.
                                                             (line 2765)
* system variable, myisam_max_sort_file_size: server-system-variables.
                                                             (line 2784)
* system variable, myisam_recover_options: server-system-variables.
                                                             (line 2809)
* system variable, myisam_repair_threads: server-system-variables.
                                                             (line 2818)
* system variable, myisam_sort_buffer_size: server-system-variables.
                                                             (line 2847)
* system variable, myisam_stats_method:  server-system-variables.
                                                             (line 2878)
* system variable, myisam_use_mmap:      server-system-variables.
                                                             (line 2912)
* system variable, named_pipe:           server-system-variables.
                                                             (line 2928)
* system variable, net_buffer_length:    server-system-variables.
                                                             (line 2938)
* system variable, net_read_timeout:     server-system-variables.
                                                             (line 2969)
* system variable, net_retry_count:      server-system-variables.
                                                             (line 2993)
* system variable, net_write_timeout:    server-system-variables.
                                                             (line 3018)
* system variable, new:                  server-system-variables.
                                                             (line 3037)
* system variable, old:                  server-system-variables.
                                                             (line 3056)
* system variable, old_passwords:        server-system-variables.
                                                             (line 3078)
* system variable, one_shot:             server-system-variables.
                                                             (line 3095)
* system variable, open_files_limit:     server-system-variables.
                                                             (line 3100)
* system variable, optimizer_prune_level: server-system-variables.
                                                             (line 3122)
* system variable, optimizer_search_depth: server-system-variables.
                                                             (line 3141)
* system variable, optimizer_switch:     server-system-variables.
                                                             (line 3166)
* system variable, optimizer_use_mrr:    server-system-variables.
                                                             (line 3233)
* system variable, pid_file:             server-system-variables.
                                                             (line 3267)
* system variable, plugin_dir:           server-system-variables.
                                                             (line 3283)
* system variable, port:                 server-system-variables.
                                                             (line 3299)
* system variable, preload_buffer_size:  server-system-variables.
                                                             (line 3316)
* system variable, protocol_version:     server-system-variables.
                                                             (line 3333)
* system variable, query_alloc_block_size: server-system-variables.
                                                             (line 3343)
* system variable, query_cache_limit:    server-system-variables.
                                                             (line 3369)
* system variable, query_cache_min_res_unit: server-system-variables.
                                                             (line 3393)
* system variable, query_cache_size:     server-system-variables.
                                                             (line 3418)
* system variable, query_cache_type:     server-system-variables.
                                                             (line 3451)
* system variable, query_cache_wlock_invalidate: server-system-variables.
                                                             (line 3486)
* system variable, query_prealloc_size:  server-system-variables.
                                                             (line 3508)
* system variable, range_alloc_block_size: server-system-variables.
                                                             (line 3536)
* system variable, read_buffer_size:     server-system-variables.
                                                             (line 3555)
* system variable, read_only:            server-system-variables.
                                                             (line 3583)
* system variable, read_rnd_buffer_size: server-system-variables.
                                                             (line 3630)
* system variable, relay_log_purge:      server-system-variables.
                                                             (line 3660)
* system variable, relay_log_recovery:   replication-options-slave.
                                                             (line  771)
* system variable, relay_log_space_limit: server-system-variables.
                                                             (line 3677)
* system variable, report_host:          server-system-variables.
                                                             (line 3700)
* system variable, report_password:      server-system-variables.
                                                             (line 3705)
* system variable, report_port:          server-system-variables.
                                                             (line 3710)
* system variable, report_user:          server-system-variables.
                                                             (line 3715)
* system variable, rpl_semi_sync_master_enabled: server-system-variables.
                                                             (line 3720)
* system variable, rpl_semi_sync_master_reply_log_file_pos: server-system-variables.
                                                             (line 3729)
* system variable, rpl_semi_sync_master_timeout: server-system-variables.
                                                             (line 3736)
* system variable, rpl_semi_sync_master_trace_level: server-system-variables.
                                                             (line 3746)
* system variable, rpl_semi_sync_slave_enabled: server-system-variables.
                                                             (line 3753)
* system variable, rpl_semi_sync_slave_trace_level: server-system-variables.
                                                             (line 3762)
* system variable, secure_auth:          server-system-variables.
                                                             (line 3769)
* system variable, secure_backup_file_priv: server-system-variables.
                                                             (line 3795)
* system variable, secure_file_priv:     server-system-variables.
                                                             (line 3803)
* system variable, server_id:            server-system-variables.
                                                             (line 3825)
* system variable, shared_memory:        server-system-variables.
                                                             (line 3846)
* system variable, shared_memory_base_name: server-system-variables.
                                                             (line 3856)
* system variable, skip_external_locking: server-system-variables.
                                                             (line 3868)
* system variable, skip_networking:      server-system-variables.
                                                             (line 3873)
* system variable, skip_show_database:   server-system-variables.
                                                             (line 3882)
* system variable, slave_compressed_protocol: replication-options-slave.
                                                             (line  868)
* system variable, slave_exec_mode:      replication-options-slave.
                                                             (line  885)
* system variable, slave_load_tmpdir:    replication-options-slave.
                                                             (line  905)
* system variable, slave_net_timeout:    replication-options-slave.
                                                             (line  922)
* system variable, slave_skip_errors:    replication-options-slave.
                                                             (line  942)
* system variable, slave_transaction_retries: replication-options-slave.
                                                             (line  959)
* system variable, slow_launch_time:     server-system-variables.
                                                             (line 3896)
* system variable, slow_query_log:       server-system-variables.
                                                             (line 3912)
* system variable, slow_query_log_file:  server-system-variables.
                                                             (line 3922)
* system variable, socket:               server-system-variables.
                                                             (line 3940)
* system variable, sort_buffer_size:     server-system-variables.
                                                             (line 3963)
* system variable, sql_mode:             server-system-variables.
                                                             (line 3993)
* system variable, sql_select_limit:     server-system-variables.
                                                             (line 4032)
* system variable, sql_slave_skip_counter: replication-options-slave.
                                                             (line  649)
* system variable, ssl_ca:               server-system-variables.
                                                             (line 4058)
* system variable, ssl_capath:           server-system-variables.
                                                             (line 4073)
* system variable, ssl_cert:             server-system-variables.
                                                             (line 4089)
* system variable, ssl_cipher:           server-system-variables.
                                                             (line 4105)
* system variable, ssl_key:              server-system-variables.
                                                             (line 4120)
* system variable, storage_engine:       server-system-variables.
                                                             (line 4136)
* system variable, sync_binlog:          replication-options-binary-log.
                                                             (line  459)
* system variable, sync_frm:             server-system-variables.
                                                             (line 4148)
* system variable, sync_master_info:     replication-options-slave.
                                                             (line  782)
* system variable, sync_relay_log:       replication-options-slave.
                                                             (line  809)
* system variable, sync_relay_log_info:  replication-options-slave.
                                                             (line  840)
* system variable, system_time_zone:     server-system-variables.
                                                             (line 4167)
* system variable, table_definition_cache: server-system-variables.
                                                             (line 4189)
* system variable, table_lock_wait_timeout: server-system-variables.
                                                             (line 4218)
* system variable, table_open_cache:     server-system-variables.
                                                             (line 4235)
* system variable, thread_cache_size:    server-system-variables.
                                                             (line 4258)
* system variable, thread_concurrency:   server-system-variables.
                                                             (line 4286)
* system variable, thread_handling:      server-system-variables.
                                                             (line 4306)
* system variable, thread_pool_size:     server-system-variables.
                                                             (line 4346)
* system variable, thread_stack:         server-system-variables.
                                                             (line 4367)
* system variable, time_format:          server-system-variables.
                                                             (line 4396)
* system variable, time_zone:            server-system-variables.
                                                             (line 4400)
* system variable, timed_mutexes:        server-system-variables.
                                                             (line 4418)
* system variable, tmp_table_size:       server-system-variables.
                                                             (line 4440)
* system variable, tmpdir:               server-system-variables.
                                                             (line 4465)
* system variable, transaction_alloc_block_size: server-system-variables.
                                                             (line 4498)
* system variable, transaction_prealloc_size: server-system-variables.
                                                             (line 4518)
* system variable, tx_isolation:         server-system-variables.
                                                             (line 4551)
* system variable, updatable_views_with_limit: server-system-variables.
                                                             (line 4576)
* system variable, version:              server-system-variables.
                                                             (line 4604)
* system variable, version_comment:      server-system-variables.
                                                             (line 4615)
* system variable, version_compile_machine: server-system-variables.
                                                             (line 4621)
* system variable, version_compile_os:   server-system-variables.
                                                             (line 4625)
* system variable, wait_timeout:         server-system-variables.
                                                             (line 4635)
* system variables <1>:                  show-variables.     (line    6)
* system variables <2>:                  using-system-variables.
                                                             (line   11)
* system variables:                      server-system-variables.
                                                             (line    6)
* system variables, and replication:     replication-features-variables.
                                                             (line    6)
* system, privilege:                     privilege-system.   (line   16)
* system, security:                      security.           (line   14)
* system_time_zone system variable:      server-system-variables.
                                                             (line 4167)
* SYSTEM_USER():                         information-functions.
                                                             (line  473)
* tab (\t) <1>:                          load-data.          (line  428)
* tab (\t):                              string-syntax.      (line   61)
* tab option, mysqldump:                 mysqldump.          (line  760)
* table aliases:                         select.             (line  157)
* table cache:                           table-cache.        (line    6)
* Table Dump, thread command:            thread-commands.    (line  128)
* table is full <1>:                     full-table.         (line    6)
* table is full:                         server-session-variables.
                                                             (line   80)
* Table lock, thread state:              general-thread-states.
                                                             (line  303)
* Table Monitor, InnoDB <1>:             innodb-troubleshooting-datadict.
                                                             (line   57)
* Table Monitor, InnoDB:                 innodb-monitors.    (line   12)
* table names, case sensitivity:         identifier-case-sensitivity.
                                                             (line    6)
* table names, case-sensitivity:         extensions-to-ansi. (line   38)
* table option, mysql:                   mysql-command-options.
                                                             (line  453)
* table option, mysqlaccess:             mysqlaccess.        (line  145)
* table scans, avoiding:                 how-to-avoid-table-scan.
                                                             (line    6)
* table types, choosing:                 storage-engines.    (line   24)
* table, changing <1>:                   alter-table-problems.
                                                             (line    6)
* table, changing:                       alter-table.        (line    6)
* table, deleting:                       drop-table.         (line    6)
* table, rebuilding:                     rebuilding-tables.  (line    6)
* table, row size:                       storage-requirements.
                                                             (line    9)
* table-level locking:                   internal-locking.   (line    6)
* table_definition_cache system variable: server-system-variables.
                                                             (line 4189)
* table_lock_wait_timeout system variable: server-system-variables.
                                                             (line 4218)
* table_open_cache:                      table-cache.        (line    6)
* table_open_cache system variable:      server-system-variables.
                                                             (line 4235)
* TABLE_PRIVILEGES, INFORMATION_SCHEMA table: table-privileges-table.
                                                             (line    6)
* tables option, mysqlcheck:             mysqlcheck.         (line  346)
* tables option, mysqldump:              mysqldump.          (line  787)
* tables, BLACKHOLE:                     blackhole-storage-engine.
                                                             (line    6)
* tables, changing column order:         change-column-order.
                                                             (line    6)
* tables, checking:                      myisamchk-check-options.
                                                             (line    6)
* tables, closing:                       table-cache.        (line    6)
* tables, compressed:                    myisampack.         (line    6)
* tables, compressed format:             compressed-format.  (line    6)
* tables, const:                         using-explain.      (line  134)
* tables, constant:                      where-optimizations.
                                                             (line   50)
* tables, copying:                       create-table.       (line 1103)
* tables, counting rows:                 counting-rows.      (line    6)
* tables, creating:                      creating-tables.    (line    6)
* tables, CSV:                           csv-storage-engine. (line   11)
* tables, defragment:                    dynamic-format.     (line   16)
* tables, defragmenting <1>:             optimize-table.     (line    6)
* tables, defragmenting:                 maintenance-schedule.
                                                             (line   38)
* tables, deleting rows:                 deleting-from-related-tables.
                                                             (line    6)
* tables, displaying:                    mysqlshow.          (line    6)
* tables, displaying status:             show-table-status.  (line    6)
* tables, dumping <1>:                   mysqlhotcopy.       (line    6)
* tables, dumping:                       mysqldump.          (line    6)
* tables, dynamic:                       dynamic-format.     (line    6)
* tables, error checking:                check.              (line    6)
* tables, EXAMPLE:                       example-storage-engine.
                                                             (line    6)
* tables, Falcon:                        se-falcon.          (line   17)
* tables, FEDERATED:                     federated-storage-engine.
                                                             (line   13)
* tables, flush:                         mysqladmin.         (line  206)
* tables, fragmentation:                 optimize-table.     (line    6)
* tables, HEAP:                          memory-storage-engine.
                                                             (line    6)
* tables, host:                          request-access.     (line  150)
* tables, improving performance:         data-size.          (line    6)
* tables, information:                   table-info.         (line    6)
* tables, information about:             getting-information.
                                                             (line    6)
* TABLES, INFORMATION_SCHEMA table:      tables-table.       (line    6)
* tables, InnoDB:                        innodb.             (line   23)
* tables, loading data:                  loading-tables.     (line    6)
* tables, maintenance:                   mysqlcheck.         (line    6)
* tables, maintenance schedule:          maintenance-schedule.
                                                             (line    6)
* tables, maximum size:                  full-table.         (line    6)
* tables, MEMORY:                        memory-storage-engine.
                                                             (line    6)
* tables, MERGE:                         merge-storage-engine.
                                                             (line   10)
* tables, merging:                       merge-storage-engine.
                                                             (line   10)
* tables, multiple:                      multiple-tables.    (line    6)
* tables, MyISAM:                        myisam-storage-engine.
                                                             (line   13)
* tables, names:                         identifiers.        (line   13)
* tables, open:                          table-cache.        (line    6)
* tables, opening:                       table-cache.        (line    6)
* tables, optimizing:                    table-optimization. (line    6)
* tables, partitioning:                  merge-storage-engine.
                                                             (line   10)
* tables, repair:                        mysqlcheck.         (line    6)
* tables, repairing:                     repair.             (line    6)
* tables, retrieving data:               retrieving-data.    (line   18)
* tables, selecting columns:             selecting-columns.  (line    6)
* tables, selecting rows:                selecting-rows.     (line    6)
* tables, sorting rows:                  sorting-rows.       (line    6)
* tables, symbolic links:                symbolic-links-to-tables.
                                                             (line    6)
* tables, system:                        using-explain.      (line  129)
* tables, too many:                      creating-many-tables.
                                                             (line    6)
* tables, unique ID for last row:        getting-unique-id.  (line    6)
* tables, updating:                      ansi-diff-transactions.
                                                             (line    6)
* Tablespace Monitor, InnoDB <1>:        innodb-monitors.    (line   12)
* Tablespace Monitor, InnoDB <2>:        innodb-file-space.  (line   66)
* Tablespace Monitor, InnoDB:            innodb-backup.      (line  102)
* TABLESPACE, INFORMATION_SCHEMA table:  tablespaces-table.  (line    6)
* TAN():                                 mathematical-functions.
                                                             (line  546)
* tar, problems on Solaris <1>:          solaris.            (line   11)
* tar, problems on Solaris:              solaris-installation.
                                                             (line    6)
* tc-heuristic-recover option, mysqld:   server-options.     (line 1652)
* Tcl API:                               apis-tcl.           (line    6)
* tcp-ip option, mysqld_multi:           mysqld-multi.       (line  130)
* TCP/IP <1>:                            windows-testing.    (line    6)
* TCP/IP:                                windows-select-server.
                                                             (line   27)
* tee command, mysql:                    mysql-commands.     (line  207)
* tee option, mysql:                     mysql-command-options.
                                                             (line  459)
* temp-pool option, mysqld:              server-options.     (line 1665)
* temporary file, write access:          mysql-install-db-problems.
                                                             (line   70)
* temporary tables, and replication:     replication-features-temptables.
                                                             (line    6)
* temporary tables, internal:            internal-temporary-tables.
                                                             (line    6)
* temporary tables, problems:            temporary-table-problems.
                                                             (line    6)
* terminal monitor, defined:             tutorial.           (line   17)
* test option, myisampack:               myisampack.         (line   99)
* testing mysqld, mysqltest:             mysql-test-suite.   (line    6)
* testing, connection to the server:     connection-access.  (line    6)
* testing, installation:                 unix-post-installation.
                                                             (line   48)
* testing, of MySQL releases:            choosing-version.   (line  127)
* testing, post-installation:            post-installation.  (line   12)
* TEXT columns, default values:          blob.               (line   55)
* TEXT columns, indexing <1>:            create-table.       (line  404)
* TEXT columns, indexing:                indexes.            (line   15)
* TEXT data type <1>:                    blob.               (line    6)
* TEXT data type:                        string-type-overview.
                                                             (line  191)
* text files, importing <1>:             mysqlimport.        (line    6)
* text files, importing:                 batch-commands.     (line    6)
* TEXT, size:                            storage-requirements.
                                                             (line  131)
* thread cache:                          connection-threads. (line    6)
* thread command, Binlog Dump:           thread-commands.    (line    8)
* thread command, Change user:           thread-commands.    (line   13)
* thread command, Close stmt:            thread-commands.    (line   17)
* thread command, Connect:               thread-commands.    (line   21)
* thread command, Connect Out:           thread-commands.    (line   25)
* thread command, Create DB:             thread-commands.    (line   29)
* thread command, Daemon:                thread-commands.    (line   33)
* thread command, Debug:                 thread-commands.    (line   38)
* thread command, Delayed insert:        thread-commands.    (line   42)
* thread command, Drop DB:               thread-commands.    (line   46)
* thread command, Error:                 thread-commands.    (line   50)
* thread command, Execute:               thread-commands.    (line   52)
* thread command, Fetch:                 thread-commands.    (line   56)
* thread command, Field List:            thread-commands.    (line   61)
* thread command, Init DB:               thread-commands.    (line   65)
* thread command, Kill:                  thread-commands.    (line   69)
* thread command, Long Data:             thread-commands.    (line   73)
* thread command, Ping:                  thread-commands.    (line   78)
* thread command, Prepare:               thread-commands.    (line   82)
* thread command, Processlist:           thread-commands.    (line   86)
* thread command, Query:                 thread-commands.    (line   90)
* thread command, Quit:                  thread-commands.    (line   94)
* thread command, Refresh:               thread-commands.    (line   98)
* thread command, Register Slave:        thread-commands.    (line  103)
* thread command, Reset stmt:            thread-commands.    (line  107)
* thread command, Set option:            thread-commands.    (line  111)
* thread command, Shutdown:              thread-commands.    (line  116)
* thread command, Sleep:                 thread-commands.    (line  120)
* thread command, Statistics:            thread-commands.    (line  124)
* thread command, Table Dump:            thread-commands.    (line  128)
* thread command, Time:                  thread-commands.    (line  132)
* thread commands:                       thread-commands.    (line    6)
* thread packages, differences between:  thread-packages.    (line    6)
* thread pooling:                        connection-threads. (line    6)
* thread state, After create:            general-thread-states.
                                                             (line   11)
* thread state, allocating local table:  delayed-insert-thread-states.
                                                             (line   17)
* thread state, Analyzing:               general-thread-states.
                                                             (line   18)
* thread state, Changing master:         slave-connection-thread-states.
                                                             (line    9)
* thread state, Checking master version: slave-io-thread-states.
                                                             (line   20)
* thread state, checking permissions:    general-thread-states.
                                                             (line   23)
* thread state, Checking table:          general-thread-states.
                                                             (line   28)
* thread state, cleaning up:             general-thread-states.
                                                             (line   32)
* thread state, Clearing:                event-scheduler-thread-states.
                                                             (line   10)
* thread state, closing tables:          general-thread-states.
                                                             (line   37)
* thread state, Connecting to master:    slave-io-thread-states.
                                                             (line   16)
* thread state, converting HEAP to MyISAM: general-thread-states.
                                                             (line   44)
* thread state, copy to tmp table:       general-thread-states.
                                                             (line   49)
* thread state, Copying to group table:  general-thread-states.
                                                             (line   55)
* thread state, Copying to tmp table:    general-thread-states.
                                                             (line   60)
* thread state, Copying to tmp table on disk: general-thread-states.
                                                             (line   64)
* thread state, Creating delayed handler: delayed-insert-thread-states.
                                                             (line   22)
* thread state, Creating index:          general-thread-states.
                                                             (line   71)
* thread state, Creating sort index:     general-thread-states.
                                                             (line   76)
* thread state, creating table:          general-thread-states.
                                                             (line   81)
* thread state, Creating tmp table:      general-thread-states.
                                                             (line   86)
* thread state, deleting from main table: general-thread-states.
                                                             (line   93)
* thread state, deleting from reference tables: general-thread-states.
                                                             (line   99)
* thread state, discard_or_import_tablespace: general-thread-states.
                                                             (line  104)
* thread state, end:                     general-thread-states.
                                                             (line  109)
* thread state, executing:               general-thread-states.
                                                             (line  116)
* thread state, Execution of init_command: general-thread-states.
                                                             (line  120)
* thread state, Finished reading one binlog; switching to next binlog: master-thread-states.
                                                             (line   17)
* thread state, Flushing tables:         general-thread-states.
                                                             (line  130)
* thread state, freeing items:           general-thread-states.
                                                             (line  125)
* thread state, FULLTEXT initialization: general-thread-states.
                                                             (line  135)
* thread state, got handler lock:        delayed-insert-thread-states.
                                                             (line   26)
* thread state, got old table:           delayed-insert-thread-states.
                                                             (line   32)
* thread state, Has read all relay log; waiting for the slave I/O thread to update it: slave-sql-thread-states.
                                                             (line   18)
* thread state, Has sent all binlog to slave; waiting for binlog to be updated: master-thread-states.
                                                             (line   22)
* thread state, init:                    general-thread-states.
                                                             (line  140)
* thread state, Initialized:             event-scheduler-thread-states.
                                                             (line   15)
* thread state, insert:                  delayed-insert-thread-states.
                                                             (line   74)
* thread state, Killed:                  general-thread-states.
                                                             (line  146)
* thread state, Killing slave:           slave-connection-thread-states.
                                                             (line   14)
* thread state, Locked:                  general-thread-states.
                                                             (line  155)
* thread state, logging slow query:      general-thread-states.
                                                             (line  159)
* thread state, login:                   general-thread-states.
                                                             (line  168)
* thread state, Making temp file:        slave-sql-thread-states.
                                                             (line   25)
* thread state, NULL:                    general-thread-states.
                                                             (line  163)
* thread state, Opening master dump table: slave-connection-thread-states.
                                                             (line   18)
* thread state, Opening table:           general-thread-states.
                                                             (line  173)
* thread state, Opening tables:          general-thread-states.
                                                             (line  173)
* thread state, preparing:               general-thread-states.
                                                             (line  181)
* thread state, Purging old relay logs:  general-thread-states.
                                                             (line  185)
* thread state, query end:               general-thread-states.
                                                             (line  189)
* thread state, Queueing master event to the relay log: slave-io-thread-states.
                                                             (line   58)
* thread state, Reading event from the relay log: slave-sql-thread-states.
                                                             (line   13)
* thread state, Reading from net:        general-thread-states.
                                                             (line  194)
* thread state, Reading master dump table data: slave-connection-thread-states.
                                                             (line   22)
* thread state, Rebuilding the index on master dump table: slave-connection-thread-states.
                                                             (line   26)
* thread state, Reconnecting after a failed binlog dump request: slave-io-thread-states.
                                                             (line   45)
* thread state, Reconnecting after a failed master event read: slave-io-thread-states.
                                                             (line   70)
* thread state, Registering slave on master: slave-io-thread-states.
                                                             (line   25)
* thread state, Removing duplicates:     general-thread-states.
                                                             (line  198)
* thread state, removing tmp table:      general-thread-states.
                                                             (line  205)
* thread state, rename:                  general-thread-states.
                                                             (line  211)
* thread state, rename result table:     general-thread-states.
                                                             (line  215)
* thread state, Reopen tables:           general-thread-states.
                                                             (line  221)
* thread state, Repair by sorting:       general-thread-states.
                                                             (line  227)
* thread state, Repair done:             general-thread-states.
                                                             (line  231)
* thread state, Repair with keycache:    general-thread-states.
                                                             (line  236)
* thread state, Requesting binlog dump:  slave-io-thread-states.
                                                             (line   30)
* thread state, reschedule:              delayed-insert-thread-states.
                                                             (line   78)
* thread state, Rolling back:            general-thread-states.
                                                             (line  241)
* thread state, Saving state:            general-thread-states.
                                                             (line  245)
* thread state, Searching rows for update: general-thread-states.
                                                             (line  252)
* thread state, Sending binlog event to slave: master-thread-states.
                                                             (line   11)
* thread state, setup:                   general-thread-states.
                                                             (line  263)
* thread state, Sorting for group:       general-thread-states.
                                                             (line  268)
* thread state, Sorting for order:       general-thread-states.
                                                             (line  272)
* thread state, Sorting index:           general-thread-states.
                                                             (line  276)
* thread state, Sorting result:          general-thread-states.
                                                             (line  281)
* thread state, statistics:              general-thread-states.
                                                             (line  286)
* thread state, storing row into queue:  delayed-insert-thread-states.
                                                             (line   39)
* thread state, System lock:             general-thread-states.
                                                             (line  291)
* thread state, Table lock:              general-thread-states.
                                                             (line  303)
* thread state, update:                  delayed-insert-thread-states.
                                                             (line   44)
* thread state, Updating:                general-thread-states.
                                                             (line  308)
* thread state, updating main table:     general-thread-states.
                                                             (line  312)
* thread state, updating reference tables: general-thread-states.
                                                             (line  318)
* thread state, upgrading lock:          delayed-insert-thread-states.
                                                             (line   83)
* thread state, User lock:               general-thread-states.
                                                             (line  323)
* thread state, waiting for delay_list:  delayed-insert-thread-states.
                                                             (line   46)
* thread state, waiting for handler insert: delayed-insert-thread-states.
                                                             (line   53)
* thread state, waiting for handler lock: delayed-insert-thread-states.
                                                             (line   58)
* thread state, waiting for handler open: delayed-insert-thread-states.
                                                             (line   64)
* thread state, Waiting for INSERT:      delayed-insert-thread-states.
                                                             (line   88)
* thread state, Waiting for master to send event: slave-io-thread-states.
                                                             (line   49)
* thread state, Waiting for master update: slave-io-thread-states.
                                                             (line   12)
* thread state, Waiting for next activation: event-scheduler-thread-states.
                                                             (line   20)
* thread state, Waiting for scheduler to stop: event-scheduler-thread-states.
                                                             (line   25)
* thread state, Waiting for slave mutex on exit <1>: slave-sql-thread-states.
                                                             (line   31)
* thread state, Waiting for slave mutex on exit: slave-io-thread-states.
                                                             (line   84)
* thread state, Waiting for table:       general-thread-states.
                                                             (line  330)
* thread state, Waiting for tables:      general-thread-states.
                                                             (line  330)
* thread state, Waiting for the next event in relay log: slave-sql-thread-states.
                                                             (line    9)
* thread state, Waiting for the slave SQL thread to free enough relay log space: slave-io-thread-states.
                                                             (line   76)
* thread state, Waiting on cond:         general-thread-states.
                                                             (line  344)
* thread state, Waiting on empty queue:  event-scheduler-thread-states.
                                                             (line   30)
* thread state, Waiting to finalize termination: master-thread-states.
                                                             (line   29)
* thread state, Waiting to reconnect after a failed binlog dump request: slave-io-thread-states.
                                                             (line   37)
* thread state, Waiting to reconnect after a failed master event read: slave-io-thread-states.
                                                             (line   63)
* thread state, Writing to net:          general-thread-states.
                                                             (line  349)
* thread states, delayed inserts:        delayed-insert-thread-states.
                                                             (line    6)
* thread states, event scheduler:        event-scheduler-thread-states.
                                                             (line    6)
* thread states, general:                general-thread-states.
                                                             (line    6)
* thread states, replication master:     master-thread-states.
                                                             (line    6)
* thread states, replication slave <1>:  slave-connection-thread-states.
                                                             (line    6)
* thread states, replication slave <2>:  slave-sql-thread-states.
                                                             (line    6)
* thread states, replication slave:      slave-io-thread-states.
                                                             (line    6)
* thread support:                        which-os.           (line    6)
* thread support, non-native:            mit-pthreads.       (line    6)
* thread_cache_size system variable:     server-system-variables.
                                                             (line 4258)
* thread_concurrency system variable:    server-system-variables.
                                                             (line 4286)
* thread_handling system variable:       server-system-variables.
                                                             (line 4306)
* thread_pool_size system variable:      server-system-variables.
                                                             (line 4346)
* thread_stack system variable:          server-system-variables.
                                                             (line 4367)
* threaded clients:                      threaded-clients.   (line    6)
* threads <1>:                           mysql-internals.    (line   11)
* threads <2>:                           show-processlist.   (line    6)
* threads:                               mysqladmin.         (line  188)
* threads, display:                      show-processlist.   (line    6)
* threads, RTS:                          rts-threads.        (line    6)
* TIME data type <1>:                    time.               (line    6)
* TIME data type:                        date-and-time-type-overview.
                                                             (line   63)
* time types:                            storage-requirements.
                                                             (line   57)
* time zone problems:                    timezone-problems.  (line    6)
* time zone tables:                      mysql-tzinfo-to-sql.
                                                             (line    6)
* time zones, and replication:           replication-features-timezone.
                                                             (line    6)
* time zones, leap seconds:              time-zone-leap-seconds.
                                                             (line    6)
* time zones, support:                   time-zone-support.  (line   11)
* time zones, upgrading:                 time-zone-upgrades. (line    6)
* TIME():                                date-and-time-functions.
                                                             (line  890)
* Time, thread command:                  thread-commands.    (line  132)
* time_format system variable:           server-system-variables.
                                                             (line 4396)
* TIME_FORMAT():                         date-and-time-functions.
                                                             (line  969)
* TIME_TO_SEC():                         date-and-time-functions.
                                                             (line  983)
* time_zone system variable:             server-system-variables.
                                                             (line 4400)
* timed_mutexes system variable:         server-system-variables.
                                                             (line 4418)
* TIMEDIFF():                            date-and-time-functions.
                                                             (line  900)
* timeout <1>:                           insert-delayed.     (line  126)
* timeout <2>:                           miscellaneous-functions.
                                                             (line   40)
* timeout:                               server-system-variables.
                                                             (line  980)
* timeout, connect_timeout variable <1>: mysqladmin.         (line  437)
* timeout, connect_timeout variable:     mysql-command-options.
                                                             (line  537)
* timeout, shutdown_timeout variable:    mysqladmin.         (line  442)
* timeouts (replication):                replication-features-timeout.
                                                             (line    6)
* timer-length option, mysqlslap:        mysqlslap.          (line  460)
* TIMESTAMP data type <1>:               datetime.           (line   10)
* TIMESTAMP data type:                   date-and-time-type-overview.
                                                             (line   31)
* timestamp session variable:            server-session-variables.
                                                             (line  254)
* TIMESTAMP():                           date-and-time-functions.
                                                             (line  913)
* TIMESTAMP, and NULL values:            problems-with-null. (line   71)
* TIMESTAMP, and replication:            replication-features-auto-increment.
                                                             (line    6)
* TIMESTAMPADD():                        date-and-time-functions.
                                                             (line  925)
* TIMESTAMPDIFF():                       date-and-time-functions.
                                                             (line  946)
* timezone option, mysqld_safe:          mysqld-safe.        (line  222)
* TINYBLOB data type:                    string-type-overview.
                                                             (line  165)
* TINYINT data type:                     numeric-type-overview.
                                                             (line   40)
* TINYTEXT data type:                    string-type-overview.
                                                             (line  172)
* tips, optimization:                    miscellaneous-optimization-tips.
                                                             (line    6)
* tmp_table_size system variable:        server-system-variables.
                                                             (line 4440)
* TMPDIR environment variable <1>:       environment-variables.
                                                             (line   18)
* TMPDIR environment variable:           mysql-install-db-problems.
                                                             (line   83)
* tmpdir option, myisamchk:              myisamchk-repair-options.
                                                             (line  113)
* tmpdir option, myisampack:             myisampack.         (line  103)
* tmpdir option, mysql_upgrade:          mysql-upgrade.      (line  114)
* tmpdir option, mysqld:                 server-options.     (line 1699)
* tmpdir option, mysqlhotcopy:           mysqlhotcopy.       (line  170)
* tmpdir system variable:                server-system-variables.
                                                             (line 4465)
* to-last-log option, mysqlbinlog:       mysqlbinlog.        (line  342)
* TO_DAYS():                             date-and-time-functions.
                                                             (line  992)
* TODO, symlinks:                        symbolic-links-to-tables.
                                                             (line   74)
* tools, command-line:                   mysql.              (line   14)
* tools, list of:                        tools-used-to-create-mysql.
                                                             (line    6)
* tools, mysqld_multi:                   mysqld-multi.       (line    6)
* tools, mysqld_safe:                    mysqld-safe.        (line    6)
* Touches():                             functions-that-test-spatial-relationships-between-geometries.
                                                             (line   76)
* trace DBI method:                      using-gdb-on-mysqld.
                                                             (line   89)
* TRADITIONAL SQL mode:                  server-sql-mode.    (line   68)
* transaction isolation level:           set-transaction.    (line    6)
* transaction isolation level, READ COMMITTED: set-transaction.
                                                             (line   69)
* transaction isolation level, READ UNCOMMITTED: set-transaction.
                                                             (line   61)
* transaction isolation level, REPEATABLE READ: set-transaction.
                                                             (line  104)
* transaction isolation level, SERIALIZABLE: set-transaction.
                                                             (line  126)
* transaction-isolation option, mysqld:  server-options.     (line 1682)
* transaction-safe tables <1>:           innodb.             (line   23)
* transaction-safe tables:               ansi-diff-transactions.
                                                             (line    6)
* transaction_alloc_block_size system variable: server-system-variables.
                                                             (line 4498)
* transaction_prealloc_size system variable: server-system-variables.
                                                             (line 4518)
* transactions, and replication <1>:     replication-features-transactions.
                                                             (line    6)
* transactions, and replication:         replication-features-timeout.
                                                             (line    6)
* transactions, support <1>:             innodb.             (line   23)
* transactions, support:                 ansi-diff-transactions.
                                                             (line    6)
* Translators, list of:                  documenters-translators.
                                                             (line    6)
* trigger restrictions:                  stored-program-restrictions.
                                                             (line    6)
* trigger, creating:                     create-trigger.     (line    6)
* trigger, dropping:                     drop-trigger.       (line    6)
* triggers <1>:                          triggers.           (line   11)
* triggers <2>:                          stored-programs-views.
                                                             (line   15)
* triggers <3>:                          show-triggers.      (line    6)
* triggers:                              ansi-diff-triggers. (line    6)
* triggers option, mysqldump:            mysqldump.          (line  793)
* triggers, and INSERT DELAYED:          insert.             (line  229)
* triggers, and replication <1>:         replication-features-triggers.
                                                             (line    6)
* triggers, and replication:             replication-features-invoked.
                                                             (line    6)
* TRIGGERS, INFORMATION_SCHEMA table:    triggers-table.     (line    6)
* triggers, LAST_INSERT_ID():            stored-routines-last-insert-id.
                                                             (line    6)
* triggers, metadata:                    trigger-metadata.   (line    6)
* TRIM():                                string-functions.   (line  680)
* troubleshooting, FreeBSD:              compilation-problems.
                                                             (line  104)
* troubleshooting, Solaris:              compilation-problems.
                                                             (line  104)
* TRUE <1>:                              boolean-values.     (line    6)
* TRUE:                                  number-syntax.      (line    6)
* TRUE, testing for:                     comparison-operators.
                                                             (line  128)
* TRUNCATE:                              truncate.           (line    6)
* TRUNCATE():                            mathematical-functions.
                                                             (line  555)
* TRUNCATE, and replication:             replication-features-truncate.
                                                             (line    6)
* tutorial:                              tutorial.           (line   17)
* Twin Studies, queries:                 twin.               (line   11)
* tx_isolation system variable:          server-system-variables.
                                                             (line 4551)
* type conversions <1>:                  comparison-operators.
                                                             (line   36)
* type conversions:                      type-conversion.    (line    6)
* type option, mysql_convert_table_format: mysql-convert-table-format.
                                                             (line   54)
* types, column:                         data-types.         (line   29)
* types, columns:                        choosing-types.     (line    6)
* types, data:                           data-types.         (line   29)
* types, date:                           storage-requirements.
                                                             (line   57)
* types, Date and Time:                  date-and-time-types.
                                                             (line   13)
* types, numeric:                        storage-requirements.
                                                             (line   15)
* types, of tables:                      storage-engines.    (line   24)
* types, portability:                    other-vendor-data-types.
                                                             (line    6)
* types, strings:                        string-types.       (line   14)
* types, time:                           storage-requirements.
                                                             (line   57)
* typographical conventions <1>:         mem-conventions.    (line    8)
* typographical conventions:             manual-conventions. (line    8)
* TZ environment variable <1>:           timezone-problems.  (line    6)
* TZ environment variable:               environment-variables.
                                                             (line   18)
* tz-utc option, mysqldump:              mysqldump.          (line  798)
* UCASE():                               string-functions.   (line  699)
* UCS-2:                                 charset.            (line   22)
* UDFs <1>:                              drop-function-udf.  (line    6)
* UDFs:                                  create-function-udf.
                                                             (line    6)
* UDFs, compiling:                       udf-compiling.      (line    6)
* UDFs, defined:                         adding-functions.   (line   12)
* UDFs, return values:                   udf-return-values.  (line    6)
* ulimit:                                not-enough-file-handles.
                                                             (line   30)
* UMASK environment variable <1>:        file-permissions.   (line    6)
* UMASK environment variable:            environment-variables.
                                                             (line   18)
* UMASK_DIR environment variable <1>:    file-permissions.   (line   20)
* UMASK_DIR environment variable:        environment-variables.
                                                             (line   18)
* unary minus (-):                       arithmetic-functions.
                                                             (line   58)
* unbuffered option, mysql:              mysql-command-options.
                                                             (line  465)
* UNCOMPRESS():                          encryption-functions.
                                                             (line  315)
* UNCOMPRESSED_LENGTH():                 encryption-functions.
                                                             (line  328)
* UNHEX():                               string-functions.   (line  703)
* Unicode:                               charset.            (line   22)
* Unicode Collation Algorithm:           charset-unicode-sets.
                                                             (line   87)
* UNINSTALL PLUGIN:                      uninstall-plugin.   (line    6)
* uninstalling plugins:                  uninstall-plugin.   (line    6)
* UNION <1>:                             union.              (line    6)
* UNION:                                 searching-on-two-keys.
                                                             (line    6)
* Union():                               spatial-operators.  (line   37)
* UNIQUE:                                alter-table.        (line  307)
* unique ID:                             getting-unique-id.  (line    6)
* unique key, constraint:                constraint-primary-key.
                                                             (line    6)
* unique keys, and partitioning keys:    partitioning-limitations-partitioning-keys-unique-keys.
                                                             (line    6)
* unique_checks session variable:        server-session-variables.
                                                             (line  268)
* unique_subquery join type, optimizer:  using-explain.      (line  220)
* Unix <1>:                              connector-net.      (line   15)
* Unix:                                  connector-odbc.     (line   17)
* UNIX_TIMESTAMP():                      date-and-time-functions.
                                                             (line 1017)
* UNKNOWN, testing for:                  comparison-operators.
                                                             (line  128)
* unloading, tables:                     retrieving-data.    (line   18)
* UNLOCK TABLES:                         lock-tables.        (line   12)
* unnamed views:                         unnamed-views.      (line    6)
* unpack option, myisamchk:              myisamchk-repair-options.
                                                             (line  123)
* UNSIGNED <1>:                          numeric-types.      (line    6)
* UNSIGNED:                              numeric-type-overview.
                                                             (line    6)
* UNTIL:                                 repeat-statement.   (line    6)
* updatable views:                       view-updatability.  (line    6)
* updatable_views_with_limit system variable: server-system-variables.
                                                             (line 4576)
* UPDATE:                                update.             (line    6)
* update, thread state:                  delayed-insert-thread-states.
                                                             (line   44)
* update-state option, myisamchk:        myisamchk-check-options.
                                                             (line   57)
* UpdateXML():                           xml-functions.      (line  268)
* updating main table, thread state:     general-thread-states.
                                                             (line  312)
* updating reference tables, thread state: general-thread-states.
                                                             (line  318)
* updating, releases of MySQL:           many-versions.      (line    6)
* updating, tables:                      ansi-diff-transactions.
                                                             (line    6)
* Updating, thread state:                general-thread-states.
                                                             (line  308)
* upgrading <1>:                         upgrade.            (line   10)
* upgrading:                             upgrade-downgrade.  (line   14)
* upgrading lock, thread state:          delayed-insert-thread-states.
                                                             (line   83)
* upgrading MySQL:                       mysql-upgrade.      (line    6)
* upgrading, different architecture:     copying-databases.  (line    6)
* upgrading, grant tables:               mysql-fix-privilege-tables.
                                                             (line    6)
* upgrading, to &current-series;:        upgrading-from-5-1. (line    6)
* UPPER():                               string-functions.   (line  742)
* uptime:                                mysqladmin.         (line  184)
* URLs for downloading MySQL:            getting-mysql.      (line    6)
* USE:                                   use.                (line    6)
* use command, mysql:                    mysql-commands.     (line  221)
* USE INDEX:                             index-hints.        (line    6)
* USE KEY:                               index-hints.        (line    6)
* use-frm option, mysqlcheck:            mysqlcheck.         (line  351)
* use-mysqld_safe option, mysql.server:  mysql-server.       (line   57)
* use-threads option, mysqlimport:       mysqlimport.        (line  272)
* user accounts, creating:               create-user.        (line    6)
* user accounts, renaming:               rename-user.        (line    6)
* USER environment variable <1>:         connecting.         (line  232)
* USER environment variable:             environment-variables.
                                                             (line   18)
* User lock, thread state:               general-thread-states.
                                                             (line  323)
* user names, and passwords:             user-names.         (line    6)
* user option:                           connecting.         (line  211)
* user option, mysql:                    mysql-command-options.
                                                             (line  469)
* user option, mysql.server:             mysql-server.       (line   62)
* user option, mysql_convert_table_format: mysql-convert-table-format.
                                                             (line   65)
* user option, mysql_install_db:         mysql-install-db.   (line   73)
* user option, mysql_setpermission:      mysql-setpermission.
                                                             (line   55)
* user option, mysql_upgrade:            mysql-upgrade.      (line  119)
* user option, mysqlaccess:              mysqlaccess.        (line  149)
* user option, mysqladmin:               mysqladmin.         (line  411)
* user option, mysqlbinlog:              mysqlbinlog.        (line  350)
* user option, mysqlcheck:               mysqlcheck.         (line  357)
* user option, mysqld:                   server-options.     (line 1728)
* user option, mysqld_multi:             mysqld-multi.       (line  138)
* user option, mysqld_safe:              mysqld-safe.        (line  228)
* user option, mysqldump:                mysqldump.          (line  810)
* user option, mysqlhotcopy:             mysqlhotcopy.       (line  174)
* user option, mysqlimport:              mysqlimport.        (line  268)
* user option, mysqlshow:                mysqlshow.          (line  195)
* user option, mysqlslap:                mysqlslap.          (line  465)
* user privileges, adding:               adding-users.       (line    6)
* user privileges, deleting <1>:         drop-user.          (line    6)
* user privileges, deleting:             removing-users.     (line    6)
* user privileges, dropping <1>:         drop-user.          (line    6)
* user privileges, dropping:             removing-users.     (line    6)
* user table, sorting:                   connection-access.  (line  120)
* user variables:                        user-variables.     (line    6)
* user variables, and replication:       replication-features-variables.
                                                             (line    6)
* USER():                                information-functions.
                                                             (line  477)
* User-defined functions <1>:            drop-function-udf.  (line    6)
* User-defined functions:                create-function-udf.
                                                             (line    6)
* user-defined functions, adding <1>:    adding-udf.         (line   15)
* user-defined functions, adding:        adding-functions.   (line   12)
* USER_PRIVILEGES, INFORMATION_SCHEMA table: user-privileges-table.
                                                             (line    6)
* users, adding <1>:                     quick-install.      (line  167)
* users, adding:                         installing-binary.  (line  168)
* users, deleting <1>:                   drop-user.          (line    6)
* users, deleting:                       removing-users.     (line    6)
* users, root:                           default-privileges. (line    6)
* uses, of MySQL:                        internal-use.       (line    6)
* using multiple disks to start data:    windows-symbolic-links.
                                                             (line    6)
* UTC_DATE():                            date-and-time-functions.
                                                             (line 1074)
* UTC_TIME():                            date-and-time-functions.
                                                             (line 1083)
* UTC_TIMESTAMP():                       date-and-time-functions.
                                                             (line 1092)
* UTF-8:                                 charset.            (line   22)
* utilities, program-development:        programs-overview.  (line  233)
* utility programs:                      programs-overview.  (line  152)
* UUID():                                miscellaneous-functions.
                                                             (line  199)
* UUID_SHORT():                          miscellaneous-functions.
                                                             (line  257)
* valid numbers, examples:               number-syntax.      (line    6)
* VALUES():                              miscellaneous-functions.
                                                             (line  290)
* VAR_POP():                             group-by-functions. (line  258)
* VAR_SAMP():                            group-by-functions. (line  267)
* VARBINARY data type <1>:               binary-varbinary.   (line    6)
* VARBINARY data type:                   string-type-overview.
                                                             (line  158)
* VARCHAR data type <1>:                 string-types.       (line   14)
* VARCHAR data type:                     string-type-overview.
                                                             (line  121)
* VARCHAR, size:                         storage-requirements.
                                                             (line  131)
* VARCHARACTER data type:                string-type-overview.
                                                             (line  121)
* variables, and replication:            replication-features-variables.
                                                             (line    6)
* variables, environment:                programs-overview.  (line  288)
* variables, mysqld:                     server-parameters.  (line   11)
* variables, server <1>:                 show-variables.     (line    6)
* variables, server:                     server-system-variables.
                                                             (line    6)
* variables, status <1>:                 show-status.        (line    6)
* variables, status:                     server-status-variables.
                                                             (line    6)
* variables, system <1>:                 show-variables.     (line    6)
* variables, system <2>:                 using-system-variables.
                                                             (line   11)
* variables, system:                     server-system-variables.
                                                             (line    6)
* variables, user:                       user-variables.     (line    6)
* VARIANCE():                            group-by-functions. (line  274)
* verbose option, my_print_defaults:     my-print-defaults.  (line   57)
* verbose option, myisam_ftdump:         myisam-ftdump.      (line   69)
* verbose option, myisamchk:             myisamchk-general-options.
                                                             (line   32)
* verbose option, myisampack:            myisampack.         (line  108)
* verbose option, mysql:                 mysql-command-options.
                                                             (line  473)
* verbose option, mysql_convert_table_format: mysql-convert-table-format.
                                                             (line   69)
* verbose option, mysql_install_db:      mysql-install-db.   (line   82)
* verbose option, mysql_upgrade:         mysql-upgrade.      (line  124)
* verbose option, mysql_waitpid:         mysql-waitpid.      (line   31)
* verbose option, mysqladmin:            mysqladmin.         (line  415)
* verbose option, mysqlbackup:           mysqlbackup.        (line  145)
* verbose option, mysqlbinlog:           mysqlbinlog.        (line  354)
* verbose option, mysqlcheck:            mysqlcheck.         (line  361)
* verbose option, mysqld:                server-options.     (line 1758)
* verbose option, mysqld_multi:          mysqld-multi.       (line  143)
* verbose option, mysqldump:             mysqldump.          (line  814)
* verbose option, mysqldumpslow:         mysqldumpslow.      (line   99)
* verbose option, mysqlimport:           mysqlimport.        (line  276)
* verbose option, mysqlshow:             mysqlshow.          (line  199)
* verbose option, mysqlslap:             mysqlslap.          (line  469)
* verbose option, perror:                perror.             (line   43)
* version option, comp_err:              comp-err.           (line   71)
* version option, my_print_defaults:     my-print-defaults.  (line   61)
* version option, myisamchk:             myisamchk-general-options.
                                                             (line   38)
* version option, myisampack:            myisampack.         (line  113)
* version option, mysql:                 mysql-command-options.
                                                             (line  480)
* version option, mysql_config:          mysql-config.       (line   52)
* version option, mysql_convert_table_format: mysql-convert-table-format.
                                                             (line   73)
* version option, mysql_waitpid:         mysql-waitpid.      (line   36)
* version option, mysqlaccess:           mysqlaccess.        (line  153)
* version option, mysqladmin:            mysqladmin.         (line  419)
* version option, mysqlbackup:           mysqlbackup.        (line  150)
* version option, mysqlbinlog:           mysqlbinlog.        (line  365)
* version option, mysqlcheck:            mysqlcheck.         (line  366)
* version option, mysqld:                server-options.     (line 1762)
* version option, mysqld_multi:          mysqld-multi.       (line  147)
* version option, mysqldump:             mysqldump.          (line  818)
* version option, mysqlimport:           mysqlimport.        (line  280)
* version option, mysqlshow:             mysqlshow.          (line  205)
* version option, mysqlslap:             mysqlslap.          (line  475)
* version option, perror:                perror.             (line   48)
* version option, resolve_stack_dump:    resolve-stack-dump. (line   33)
* version option, resolveip:             resolveip.          (line   24)
* version system variable:               server-system-variables.
                                                             (line 4604)
* VERSION():                             information-functions.
                                                             (line  494)
* version, choosing:                     which-version.      (line   19)
* version, latest:                       getting-mysql.      (line    6)
* version_comment system variable:       server-system-variables.
                                                             (line 4615)
* version_compile_machine system variable: server-system-variables.
                                                             (line 4621)
* version_compile_os system variable:    server-system-variables.
                                                             (line 4625)
* vertical option, mysql:                mysql-command-options.
                                                             (line  484)
* vertical option, mysqladmin:           mysqladmin.         (line  423)
* Vietnamese:                            faqs-cjk.           (line   80)
* view restrictions:                     view-restrictions.  (line    6)
* views <1>:                             views.              (line   13)
* views <2>:                             stored-programs-views.
                                                             (line   15)
* views <3>:                             create-view.        (line    6)
* views:                                 ansi-diff-views.    (line    6)
* views, algorithms:                     view-algorithms.    (line    6)
* views, and replication:                replication-features-views.
                                                             (line    6)
* VIEWS, INFORMATION_SCHEMA table:       views-table.        (line    6)
* Views, limitations:                    view-restrictions.  (line   82)
* views, metadata:                       view-metadata.      (line    6)
* Views, privileges:                     view-restrictions.  (line   82)
* Views, problems:                       view-restrictions.  (line   82)
* views, updatable <1>:                  view-updatability.  (line    6)
* views, updatable <2>:                  create-view.        (line    6)
* views, updatable:                      ansi-diff-views.    (line    6)
* virtual memory, problems while compiling: compilation-problems.
                                                             (line   38)
* Vision:                                connector-odbc-usagenotes-apptips-vision.
                                                             (line    6)
* Visual Objects:                        connector-odbc-usagenotes-apptips-microsoft-visualobjects.
                                                             (line    6)
* Visual Studio:                         windows-source-build-cmake.
                                                             (line    6)
* wait option, myisamchk:                myisamchk-general-options.
                                                             (line   42)
* wait option, myisampack:               myisampack.         (line  117)
* wait option, mysql:                    mysql-command-options.
                                                             (line  490)
* wait option, mysqladmin:               mysqladmin.         (line  428)
* wait_timeout system variable:          server-system-variables.
                                                             (line 4635)
* waiting for delay_list, thread state:  delayed-insert-thread-states.
                                                             (line   46)
* waiting for handler insert, thread state: delayed-insert-thread-states.
                                                             (line   53)
* waiting for handler lock, thread state: delayed-insert-thread-states.
                                                             (line   58)
* waiting for handler open, thread state: delayed-insert-thread-states.
                                                             (line   64)
* Waiting for INSERT, thread state:      delayed-insert-thread-states.
                                                             (line   88)
* Waiting for master to send event, thread state: slave-io-thread-states.
                                                             (line   49)
* Waiting for master update, thread state: slave-io-thread-states.
                                                             (line   12)
* Waiting for next activation, thread state: event-scheduler-thread-states.
                                                             (line   20)
* Waiting for scheduler to stop, thread state: event-scheduler-thread-states.
                                                             (line   25)
* Waiting for slave mutex on exit, thread state <1>: slave-sql-thread-states.
                                                             (line   31)
* Waiting for slave mutex on exit, thread state: slave-io-thread-states.
                                                             (line   84)
* Waiting for table, thread state:       general-thread-states.
                                                             (line  330)
* Waiting for tables, thread state:      general-thread-states.
                                                             (line  330)
* Waiting for the next event in relay log, thread state: slave-sql-thread-states.
                                                             (line    9)
* Waiting for the slave SQL thread to free enough relay log space, thread state: slave-io-thread-states.
                                                             (line   76)
* Waiting on cond, thread state:         general-thread-states.
                                                             (line  344)
* Waiting on empty queue, thread state:  event-scheduler-thread-states.
                                                             (line   30)
* Waiting to finalize termination, thread state: master-thread-states.
                                                             (line   29)
* Waiting to reconnect after a failed binlog dump request, thread state: slave-io-thread-states.
                                                             (line   37)
* Waiting to reconnect after a failed master event read, thread state: slave-io-thread-states.
                                                             (line   63)
* warning_count session variable:        server-session-variables.
                                                             (line  281)
* warnings command, mysql:               mysql-commands.     (line  225)
* WEEK():                                date-and-time-functions.
                                                             (line 1101)
* WEEKDAY():                             date-and-time-functions.
                                                             (line 1160)
* WEEKOFYEAR():                          date-and-time-functions.
                                                             (line 1170)
* WEIGHT_STRING():                       string-functions.   (line  758)
* Well-Known Binary format:              gis-wkb-format.     (line    6)
* Well-Known Text format:                gis-wkt-format.     (line    6)
* WHERE:                                 where-optimizations.
                                                             (line    6)
* where option, mysqldump:               mysqldump.          (line  822)
* WHERE, with SHOW <1>:                  extended-show.      (line    6)
* WHERE, with SHOW:                      information-schema. (line   39)
* WHILE:                                 while-statement.    (line    6)
* widths, display:                       data-types.         (line   31)
* Wildcard character (%):                string-syntax.      (line   64)
* Wildcard character (_):                string-syntax.      (line   65)
* wildcards, and LIKE:                   mysql-indexes.      (line  109)
* wildcards, in account names:           account-names.      (line   68)
* wildcards, in mysql.columns_priv table: request-access.    (line   60)
* wildcards, in mysql.db table:          request-access.     (line   27)
* wildcards, in mysql.host table:        request-access.     (line   27)
* wildcards, in mysql.procs_priv table:  request-access.     (line   60)
* wildcards, in mysql.tables_priv table: request-access.     (line   60)
* Windows <1>:                           connector-net.      (line   15)
* Windows:                               connector-odbc.     (line   17)
* windows option, mysql_install_db:      mysql-install-db.   (line   86)
* Windows, compiling on:                 windows-client-compiling.
                                                             (line    6)
* Windows, open issues:                  windows-vs-unix.    (line  162)
* Windows, upgrading:                    windows-upgrading.  (line    6)
* Windows, versus Unix:                  windows-vs-unix.    (line    6)
* with-big-tables option:                configure-options.  (line    6)
* with-big-tables option, configure:     configure-options.  (line  532)
* with-client-ldflags option, configure: configure-options.  (line  354)
* with-debug option, configure:          configure-options.  (line  472)
* with-embedded-server option, configure: configure-options. (line  318)
* with-extra-charsets option, configure: configure-options.  (line  457)
* with-libevent option, configure:       configure-options.  (line  548)
* with-unix-socket-path option, configure: configure-options.
                                                             (line  342)
* with-zlib-dir option, configure:       configure-options.  (line  522)
* Within():                              functions-that-test-spatial-relationships-between-geometries.
                                                             (line   83)
* without-server option:                 configure-options.  (line    6)
* without-server option, configure:      configure-options.  (line  304)
* WKB format:                            gis-wkb-format.     (line    6)
* WKT format:                            gis-wkt-format.     (line    6)
* wrappers, Eiffel:                      apis-eiffel.        (line    6)
* write access, tmp:                     mysql-install-db-problems.
                                                             (line   70)
* write-binlog option, mysqlbinlog:      mysqlbinlog.        (line  369)
* write_buffer_size myisamchk variable:  myisamchk-general-options.
                                                             (line   53)
* Writing to net, thread state:          general-thread-states.
                                                             (line  349)
* X():                                   point-property-functions.
                                                             (line    9)
* X509/Certificate:                      secure-basics.      (line   31)
* XA BEGIN:                              xa-statements.      (line    6)
* XA COMMIT:                             xa-statements.      (line    6)
* XA PREPARE:                            xa-statements.      (line    6)
* XA RECOVER:                            xa-statements.      (line    6)
* XA ROLLBACK:                           xa-statements.      (line    6)
* XA START:                              xa-statements.      (line    6)
* XA transactions:                       xa.                 (line   11)
* XA transactions, transaction identifiers: xa-statements.   (line    6)
* xid, XA transaction identifier:        xa-statements.      (line    6)
* xml option, mysql:                     mysql-command-options.
                                                             (line  495)
* xml option, mysqldump:                 mysqldump.          (line  834)
* XOR, bitwise:                          bit-functions.      (line   36)
* XOR, logical:                          logical-operators.  (line   82)
* Y():                                   point-property-functions.
                                                             (line   22)
* yaSSL <1>:                             secure-using-ssl.   (line    6)
* yaSSL:                                 secure-connections. (line   13)
* Year 2000 compliance:                  y2k-issues.         (line    6)
* Year 2000 issues:                      y2k-issues.         (line    6)
* YEAR data type <1>:                    year.               (line    6)
* YEAR data type:                        date-and-time-type-overview.
                                                             (line   70)
* YEAR():                                date-and-time-functions.
                                                             (line 1179)
* YEARWEEK():                            date-and-time-functions.
                                                             (line 1187)
* Yen sign (Japanese):                   faqs-cjk.           (line   32)
* ZEROFILL <1>:                          c-api-prepared-statement-problems.
                                                             (line   13)
* ZEROFILL <2>:                          numeric-types.      (line    6)
* ZEROFILL:                              numeric-type-overview.
                                                             (line    6)
* | (bitwise OR):                        bit-functions.      (line   18)
* || (logical OR):                       logical-operators.  (line   63)
* ~:                                     bit-functions.      (line   73)



Tag Table:
Node: Top167
Node: introduction5495
Node: manual-info8369
Node: manual-conventions10899
Node: what-is15577
Node: what-is-mysql15951
Node: history20361
Node: features21545
Node: roadmap31372
Node: mysql-nutshell32837
Node: information-sources38177
Node: mailing-lists38774
Node: mailing-list-use43999
Node: forums45104
Node: irc45651
Node: mysql-enterprise-information46611
Node: bug-reports47416
Node: compatibility65514
Node: standards68575
Node: sql-mode68885
Node: ansi-mode69874
Node: extensions-to-ansi71081
Node: differences-from-ansi81220
Node: ansi-diff-select-into-table82419
Node: ansi-diff-transactions83298
Node: ansi-diff-triggers92428
Node: ansi-diff-foreign-keys92888
Node: ansi-diff-views97702
Node: ansi-diff-comments98603
Node: constraints101270
Node: constraint-primary-key103453
Node: constraint-invalid-data104932
Node: constraint-enum110717
Node: credits113319
Node: contributors113922
Node: documenters-translators122599
Node: used-libraries125022
Node: packages127558
Node: tools-used-to-create-mysql128750
Node: supporters129822
Node: installing130717
Node: general-installation-issues134770
Node: which-os136744
Node: which-version140972
Node: choosing-version141801
Node: choosing-distribution-format148699
Node: many-versions152007
Node: mysql-binaries153939
Node: getting-mysql171579
Node: verifying-package-integrity172208
Node: verifying-md5-checksum173589
Node: checking-gpg-signature175287
Node: checking-rpm-signature185002
Node: installation-layouts186391
Node: quick-standard-installation190395
Node: windows-installation191208
Node: windows-choosing-package197010
Node: windows-using-installer198872
Node: windows-install-wizard199709
Node: mysql-install-wizard-starting202426
Node: mysql-install-wizard-install-type205268
Node: mysql-install-wizard-custom-install206742
Node: mysql-install-wizard-confirmation-dialog207752
Node: mysql-install-wizard-changes208998
Node: mysql-install-wizard-upgrading212827
Node: mysql-config-wizard213661
Node: mysql-config-wizard-starting215222
Node: mysql-config-wizard-maintenance218430
Node: mysql-config-wizard-configuration-type219771
Node: mysql-config-wizard-server-type221544
Node: mysql-config-wizard-database-usage223227
Node: mysql-config-wizard-tablespace225419
Node: mysql-config-wizard-connections226516
Node: mysql-config-wizard-networking227964
Node: mysql-config-wizard-character-set229251
Node: mysql-config-wizard-service230456
Node: mysql-config-wizard-security232524
Node: mysql-config-wizard-confirmation233757
Node: windows-install-archive235536
Node: windows-extract-archive236213
Node: windows-create-option-file237391
Node: windows-select-server240865
Node: windows-server-first-start242342
Node: windows-start-command-line245945
Node: windows-start-service248190
Node: windows-testing256812
Node: windows-troubleshooting258373
Node: windows-upgrading263399
Node: windows-vs-unix266336
Node: linux-rpm273091
Node: mac-os-x-installation282571
Node: solaris-installation289842
Node: netware-installation291341
Node: installing-binary297042
Node: installing-source305850
Node: quick-install309911
Node: configure-options317235
Ref: option_configure_without-server337727
Ref: option_configure_with-embedded-server338445
Ref: option_configure_prefix338563
Ref: option_configure_with-unix-socket-path339582
Ref: option_configure_with-client-ldflags340117
Ref: option_configure_with-charset342967
Ref: option_configure_with-collation343748
Ref: option_configure_with-extra-charsets344712
Ref: option_configure_with-debug345322
Ref: option_configure_enable-debug-sync346041
Ref: option_configure_enable-dtrace347021
Ref: option_configure_enable-thread-safe-client347267
Ref: option_configure_with-zlib-dir347588
Ref: option_configure_with-big-tables348175
Ref: option_configure_disable-grant-options348659
Ref: option_configure_with-libevent348976
Ref: option_configure_enable-community-features349475
Ref: option_configure_enable-profiling349803
Ref: option_configure_with-plugins350442
Node: installing-source-tree352352
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Ref: option_configure_with-low-memory361825
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Node: mysql-install-db-problems403460
Node: automatic-start410383
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Node: copying-databases471983
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Ref: option_general_host701393
Ref: option_general_password701518
Ref: option_general_pipe701811
Ref: option_general_port702065
Ref: option_general_protocol702225
Ref: option_general_shared-memory-base-name703573
Ref: option_general_socket703911
Ref: option_general_user704637
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Ref: option_general_defaults-extra-file727148
Ref: option_general_defaults-file727444
Ref: option_general_defaults-group-suffix727667
Ref: option_general_no-defaults728107
Ref: option_general_print-defaults728333
Node: option-files-preconfigured728436
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Node: option-defaults-equals732698
Node: setting-environment-variables739881
Node: programs-server742869
Node: mysqld743509
Node: mysqld-safe744953
Ref: option_mysqld_safe_help750824
Ref: option_mysqld_safe_autoclose750879
Ref: option_mysqld_safe_basedir751366
Ref: option_mysqld_safe_core-file-size751442
Ref: option_mysqld_safe_datadir751609
Ref: option_mysqld_safe_defaults-extra-file751671
Ref: option_mysqld_safe_defaults-file751963
Ref: option_mysqld_safe_ledir752152
Ref: option_mysqld_safe_log-error752339
Ref: option_mysqld_safe_mysqld752438
Ref: option_mysqld_safe_mysqld-version752866
Ref: option_mysqld_safe_nice753400
Ref: option_mysqld_safe_no-defaults753519
Ref: option_mysqld_safe_open-files-limit753648
Ref: option_mysqld_safe_pid-file753918
Ref: option_mysqld_safe_port753992
Ref: option_mysqld_safe_skip-kill-mysqld754210
Ref: option_mysqld_safe_socket754353
Ref: option_mysqld_safe_syslog754473
Ref: option_mysqld_safe_syslog-tag754718
Ref: option_mysqld_safe_timezone755063
Ref: option_mysqld_safe_user755266
Node: mysql-server760344
Ref: option_mysql_server_basedir761986
Ref: option_mysql_server_datadir762062
Ref: option_mysql_server_pid-file762130
Ref: option_mysql_server_service-startup-timeout762246
Ref: option_mysql_server_use-mysqld_safe762613
Ref: option_mysql_server_user762731
Node: mysqld-multi762821
Ref: option_mysqld_multi_no-defaults765671
Ref: option_mysqld_multi_defaults-file765726
Ref: option_mysqld_multi_defaults-extra-file765796
Ref: option_mysqld_multi_help766195
Ref: option_mysqld_multi_config-file766250
Ref: option_mysqld_multi_example766405
Ref: option_mysqld_multi_log766460
Ref: option_mysqld_multi_mysqladmin766580
Ref: option_mysqld_multi_mysqld766694
Ref: option_mysqld_multi_no-log767405
Ref: option_mysqld_multi_password767538
Ref: option_mysqld_multi_silent767765
Ref: option_mysqld_multi_tcp-ip767820
Ref: option_mysqld_multi_user768166
Ref: option_mysqld_multi_verbose768291
Ref: option_mysqld_multi_version768333
Node: programs-installation774464
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Ref: option_comp_err_help776417
Ref: option_comp_err_charset776478
Ref: option_comp_err_debug776591
Ref: option_comp_err_debug-info776776
Ref: option_comp_err_header_file776867
Ref: option_comp_err_in_file776988
Ref: option_comp_err_name_file777112
Ref: option_comp_err_out_dir777230
Ref: option_comp_err_out_file777345
Ref: option_comp_err_statefile777453
Ref: option_comp_err_version777578
Node: make-win-bin-dist777642
Ref: option_make_win_bin_dist_debug779060
Ref: option_make_win_bin_dist_embedded779157
Ref: option_make_win_bin_dist_exe-suffix779298
Ref: option_make_win_bin_dist_no-debug779484
Ref: option_make_win_bin_dist_no-embedded779565
Ref: option_make_win_bin_dist_only-debug779647
Node: mysqlbug779861
Node: mysql-fix-privilege-tables781255
Node: mysql-install-db784105
Ref: option_mysql_install_db_basedir786074
Ref: option_mysql_install_db_force786150
Ref: option_mysql_install_db_datadir786354
Ref: option_mysql_install_db_rpm786438
Ref: option_mysql_install_db_skip-name-resolve786554
Ref: option_mysql_install_db_srcdir786722
Ref: option_mysql_install_db_user786993
Ref: option_mysql_install_db_verbose787372
Ref: option_mysql_install_db_windows787463
Node: mysql-secure-installation787562
Node: mysql-tzinfo-to-sql788427
Node: mysql-upgrade790598
Ref: option_mysql_upgrade_help794569
Ref: option_mysql_upgrade_basedir794630
Ref: option_mysql_upgrade_datadir794706
Ref: option_mysql_upgrade_debug-check794768
Ref: option_mysql_upgrade_debug-info794854
Ref: option_mysql_upgrade_force794981
Ref: option_mysql_upgrade_tmpdir795217
Ref: option_mysql_upgrade_user795368
Ref: option_mysql_upgrade_verbose795513
Node: programs-client795599
Node: mysql796349
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Ref: option_mysql_help807297
Ref: option_mysql_auto-rehash807358
Ref: option_mysql_auto-vertical-output808013
Ref: option_mysql_batch808294
Ref: option_mysql_character-sets-dir808670
Ref: option_mysql_column-names808801
Ref: option_mysql_column-type-info808862
Ref: option_mysql_comments808931
Ref: option_mysql_compress809172
Ref: option_mysql_database809302
Ref: option_mysql_debug809415
Ref: option_mysql_debug-check809603
Ref: option_mysql_debug-info809689
Ref: option_mysql_default-character-set809816
Ref: option_mysql_delimiter809955
Ref: option_mysql_disable-named-commands810068
Ref: option_mysql_execute810445
Ref: option_mysql_force810655
Ref: option_mysql_host810722
Ref: option_mysql_html810817
Ref: option_mysql_ignore-spaces810866
Ref: option_mysql_line-numbers811062
Ref: option_mysql_local-infile811169
Ref: option_mysql_named-commands811767
Ref: option_mysql_no-auto-rehash812064
Ref: option_mysql_no-beep812231
Ref: option_mysql_no-named-commands812293
Ref: option_mysql_no-pager812386
Ref: option_mysql_no-tee812474
Ref: option_mysql_one-database812587
Ref: option_mysql_pager812790
Ref: option_mysql_password813219
Ref: option_mysql_pipe813687
Ref: option_mysql_port813893
Ref: option_mysql_prompt813989
Ref: option_mysql_protocol814190
Ref: option_mysql_quick814501
Ref: option_mysql_raw814735
Ref: option_mysql_reconnect815693
Ref: option_mysql_safe-updates815936
Ref: option_mysql_secure-auth816323
Ref: option_mysql_show-warnings816712
Ref: option_mysql_sigint-ignore816865
Ref: option_mysql_silent816964
Ref: option_mysql_skip-column-names817295
Ref: option_mysql_skip-line-numbers817446
Ref: option_mysql_socket817676
Ref: option_mysql_ssl817833
Ref: option_mysql_table818025
Ref: option_mysql_tee818192
Ref: option_mysql_unbuffered818370
Ref: option_mysql_user818439
Ref: option_mysql_verbose818545
Ref: option_mysql_version818802
Ref: option_mysql_vertical818871
Ref: option_mysql_wait819087
Ref: option_mysql_xml819197
Ref: option_mysql_connect_timeout820528
Ref: option_mysql_max_allowed_packet820637
Ref: option_mysql_max_join_size820766
Ref: option_mysql_select_limit821014
Node: mysql-commands822129
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Ref: command_mysqladmin_debug846583
Ref: command_mysqladmin_drop846761
Ref: command_mysqladmin_extended-status846843
Ref: command_mysqladmin_flush-hosts847146
Ref: command_mysqladmin_flush-logs847214
Ref: command_mysqladmin_flush-privileges847256
Ref: command_mysqladmin_flush-status847332
Ref: command_mysqladmin_flush-tables847384
Ref: command_mysqladmin_flush-threads847430
Ref: command_mysqladmin_kill847483
Ref: command_mysqladmin_old-password847616
Ref: command_mysqladmin_password848063
Ref: command_mysqladmin_ping849434
Ref: command_mysqladmin_processlist849793
Ref: command_mysqladmin_reload850108
Ref: command_mysqladmin_refresh850155
Ref: command_mysqladmin_shutdown850225
Ref: command_mysqladmin_start-slave850266
Ref: command_mysqladmin_status850330
Ref: command_mysqladmin_stop-slave850391
Ref: command_mysqladmin_variables850453
Ref: command_mysqladmin_version850750
Ref: option_mysqladmin_help857654
Ref: option_mysqladmin_character-sets-dir857715
Ref: option_mysqladmin_compress857846
Ref: option_mysqladmin_count857976
Ref: option_mysqladmin_debug858112
Ref: option_mysqladmin_debug-check858310
Ref: option_mysqladmin_debug-info858396
Ref: option_mysqladmin_default-character-set858517
Ref: option_mysqladmin_force858656
Ref: option_mysqladmin_host858808
Ref: option_mysqladmin_no-beep858903
Ref: option_mysqladmin_password859047
Ref: option_mysqladmin_pipe859515
Ref: option_mysqladmin_port859721
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Ref: option_mysqladmin_relative860128
Ref: option_mysqladmin_silent860338
Ref: option_mysqladmin_sleep860435
Ref: option_mysqladmin_socket860726
Ref: option_mysqladmin_ssl860883
Ref: option_mysqladmin_user861075
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Ref: option_mysqladmin_wait861472
Ref: option_mysqladmin_connect_timeout861820
Ref: option_mysqladmin_shutdown_timeout861952
Node: mysqlcheck862080
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Ref: option_mysqlcheck_all-databases871762
Ref: option_mysqlcheck_all-in-1871945
Ref: option_mysqlcheck_analyze872141
Ref: option_mysqlcheck_auto-repair872398
Ref: option_mysqlcheck_character-sets-dir872554
Ref: option_mysqlcheck_check872685
Ref: option_mysqlcheck_check-only-changed872774
Ref: option_mysqlcheck_check-upgrade872917
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Ref: option_mysqlcheck_databases873331
Ref: option_mysqlcheck_debug873641
Ref: option_mysqlcheck_debug-check873812
Ref: option_mysqlcheck_debug-info873898
Ref: option_mysqlcheck_default-character-set874019
Ref: option_mysqlcheck_extended874158
Ref: option_mysqlcheck_fast874486
Ref: option_mysqlcheck_fix-db-names874568
Ref: option_mysqlcheck_fix-table-names874707
Ref: option_mysqlcheck_force874902
Ref: option_mysqlcheck_host874969
Ref: option_mysqlcheck_medium-check875064
Ref: option_mysqlcheck_optimize875250
Ref: option_mysqlcheck_password875303
Ref: option_mysqlcheck_pipe875771
Ref: option_mysqlcheck_port875977
Ref: option_mysqlcheck_protocol876073
Ref: option_mysqlcheck_quick876384
Ref: option_mysqlcheck_repair876711
Ref: option_mysqlcheck_silent876832
Ref: option_mysqlcheck_socket876902
Ref: option_mysqlcheck_ssl877059
Ref: option_mysqlcheck_tables877251
Ref: option_mysqlcheck_use-frm877393
Ref: option_mysqlcheck_user877589
Ref: option_mysqlcheck_verbose877695
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Node: mysqldump877874
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Ref: option_mysqldump_apply-slave-statements895652
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Ref: option_mysqldump_default-character-set898716
Ref: option_mysqldump_delayed-insert899113
Ref: option_mysqldump_delete-master-logs899257
Ref: option_mysqldump_disable-keys899446
Ref: option_mysqldump_dump-date899863
Ref: option_mysqldump_dump-slave900404
Ref: option_mysqldump_events901456
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Ref: option_mysqldump_first-slave902073
Ref: option_mysqldump_flush-logs902156
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Ref: option_mysqldump_force903122
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Ref: option_mysqldump_include-master-host-port904136
Ref: option_mysqldump_ignore-table904464
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Ref: option_mysqldump_lock-all-tables905032
Ref: option_mysqldump_lock-tables905289
Ref: option_mysqldump_log-error905964
Ref: option_mysqldump_master-data906047
Ref: option_mysqldump_no-autocommit907540
Ref: option_mysqldump_no-create-db907718
Ref: option_mysqldump_no-create-info907945
Ref: option_mysqldump_no-data908083
Ref: option_mysqldump_opt908313
Ref: option_mysqldump_order-by-primary908910
Ref: option_mysqldump_password909196
Ref: option_mysqldump_pipe909664
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Ref: option_mysqldump_protocol909966
Ref: option_mysqldump_quick910277
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Ref: option_mysqldump_result-file911079
Ref: option_mysqldump_routines911468
Ref: option_mysqldump_set-charset912387
Ref: option_mysqldump_single-transaction912579
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Ref: option_mysqldump_ssl914387
Ref: option_mysqldump_tab914579
Ref: option_mysqldump_tables915830
Ref: option_mysqldump_triggers916002
Ref: option_mysqldump_tz-utc916140
Ref: option_mysqldump_user916772
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Ref: option_mysqldump_xml917400
Ref: option_mysqldump_net_buffer_length920508
Node: mysqlimport924065
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Node: mysqlslap946383
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Ref: option_mysqlslap_auto-generate-sql-guid-primary958769
Ref: option_mysqlslap_auto-generate-sql-load-type958881
Ref: option_mysqlslap_auto-generate-sql-secondary-indexes959184
Ref: option_mysqlslap_auto-generate-sql-select-columns959349
Ref: option_mysqlslap_auto-generate-sql-unique-query-number959625
Ref: option_mysqlslap_auto-generate-sql-unique-write-number959975
Ref: option_mysqlslap_auto-generate-sql-write-number960136
Ref: option_mysqlslap_burnin960254
Ref: option_mysqlslap_commit960365
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Ref: option_mysqlslap_concurrency960616
Ref: option_mysqlslap_create960746
Ref: option_mysqlslap_create-schema960856
Ref: option_mysqlslap_csv960931
Ref: option_mysqlslap_debug961101
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Ref: option_mysqlslap_debug-info961384
Ref: option_mysqlslap_delimiter961511
Ref: option_mysqlslap_delayed-start961638
Ref: option_mysqlslap_detach961861
Ref: option_mysqlslap_engine962008
Ref: option_mysqlslap_host962109
Ref: option_mysqlslap_ignore-sql-errors962204
Ref: option_mysqlslap_iterations962390
Ref: option_mysqlslap_label962466
Ref: option_mysqlslap_number-blob-cols962580
Ref: option_mysqlslap_number-char-cols962885
Ref: option_mysqlslap_number-int-cols963025
Ref: option_mysqlslap_number-of-queries963169
Ref: option_mysqlslap_only-print963265
Ref: option_mysqlslap_password963395
Ref: option_mysqlslap_pipe963869
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Ref: option_mysqlslap_post-query964171
Ref: option_mysqlslap_shared-memory-base-name964353
Ref: option_mysqlslap_post-system964585
Ref: option_mysqlslap_pre-query964743
Ref: option_mysqlslap_pre-system964957
Ref: option_mysqlslap_preserve-schema965108
Ref: option_mysqlslap_protocol965326
Ref: option_mysqlslap_query965637
Ref: option_mysqlslap_set-random-seed965779
Ref: option_mysqlslap_silent965854
Ref: option_mysqlslap_slave965908
Ref: option_mysqlslap_socket966216
Ref: option_mysqlslap_ssl966373
Ref: option_mysqlslap_timer-length966565
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Node: programs-admin-utils967075
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Node: myisamchk972027
Node: myisamchk-general-options984468
Ref: option_myisamchk_help984933
Ref: option_myisamchk_HELP985041
Ref: option_myisamchk_debug985147
Ref: option_myisamchk_silent985338
Ref: option_myisamchk_verbose985505
Ref: option_myisamchk_version985711
Ref: option_myisamchk_wait985780
Node: myisamchk-check-options990361
Ref: option_myisamchk_check990664
Ref: option_myisamchk_check-only-changed990824
Ref: option_myisamchk_extend-check990924
Ref: option_myisamchk_fast991444
Ref: option_myisamchk_force991525
Ref: option_myisamchk_information991748
Ref: option_myisamchk_medium-check991847
Ref: option_myisamchk_read-only992036
Ref: option_myisamchk_update-state992332
Node: myisamchk-repair-options992719
Ref: option_myisamchk_backup993020
Ref: option_myisamchk_character-sets-dir993107
Ref: option_myisamchk_correct-checksum993238
Ref: option_myisamchk_data-file-length993320
Ref: option_myisamchk_extended-check993451
Ref: option_myisamchk_keys-used993794
Ref: option_myisamchk_no-symlinks994240
Ref: option_myisamchk_max-record-length994524
Ref: option_myisamchk_parallel-recover994677
Ref: option_myisamchk_quick994883
Ref: option_myisamchk_recover995111
Ref: option_myisamchk_safe-recover995682
Ref: option_myisamchk_set-character-set996278
Ref: option_myisamchk_set-collation996437
Ref: option_myisamchk_sort-recover996614
Ref: option_myisamchk_tmpdir996775
Ref: option_myisamchk_unpack997273
Node: myisamchk-other-options997366
Ref: option_myisamchk_analyze997678
Ref: option_myisamchk_block-search998303
Ref: option_myisamchk_description998414
Ref: option_myisamchk_set-auto-increment998501
Ref: option_myisamchk_sort-index998870
Ref: option_myisamchk_sort-records999023
Node: myisamchk-memory1000013
Node: myisamlog1002565
Ref: option_myisamlog_help1003451
Ref: option_myisamlog_files1003552
Ref: option_myisamlog_information1003614
Ref: option_myisamlog_offset1003674
Ref: option_myisamlog_path1003728
Ref: option_myisamlog_recovery1003779
Ref: option_myisamlog_record-position1003827
Ref: option_myisamlog_update1003922
Ref: option_myisamlog_verbose1003969
Ref: option_myisamlog_write1004127
Ref: option_myisamlog_version1004180
Node: myisampack1004222
Ref: option_myisampack_help1006300
Ref: option_myisampack_backup1006361
Ref: option_myisampack_character-sets-dir1006467
Ref: option_myisampack_debug1006598
Ref: option_myisampack_force1006769
Ref: option_myisampack_join1007402
Ref: option_myisampack_silent1008116
Ref: option_myisampack_test1008196
Ref: option_myisampack_tmpdir1008278
Ref: option_myisampack_verbose1008426
Ref: option_myisampack_version1008554
Ref: option_myisampack_wait1008623
Node: mysqlaccess1019721
Ref: option_mysqlaccess_help1023254
Ref: option_mysqlaccess_brief1023315
Ref: option_mysqlaccess_commit1023392
Ref: option_mysqlaccess_copy1023663
Ref: option_mysqlaccess_db1023739
Ref: option_mysqlaccess_debug1023808
Ref: option_mysqlaccess_host1023891
Ref: option_mysqlaccess_howto1023986
Ref: option_mysqlaccess_old_server1024091
Ref: option_mysqlaccess_password1024249
Ref: option_mysqlaccess_plan1024603
Ref: option_mysqlaccess_preview1024676
Ref: option_mysqlaccess_relnotes1024789
Ref: option_mysqlaccess_rhost1024842
Ref: option_mysqlaccess_rollback1024938
Ref: option_mysqlaccess_spassword1025024
Ref: option_mysqlaccess_superuser1025401
Ref: option_mysqlaccess_table1025509
Ref: option_mysqlaccess_user1025572
Ref: option_mysqlaccess_version1025667
Node: mysqlbackup1026298
Ref: option_mysqlbackup_help1029895
Ref: option_mysqlbackup_all1029956
Ref: option_mysqlbackup_catalog-details1030030
Ref: option_mysqlbackup_catalog-summary1030116
Ref: option_mysqlbackup_data-chunks1030198
Ref: option_mysqlbackup_data-totals1030301
Ref: option_mysqlbackup_debug1030406
Ref: option_mysqlbackup_exact1030605
Ref: option_mysqlbackup_image-order1030733
Ref: option_mysqlbackup_metadata-extra1030836
Ref: option_mysqlbackup_metadata-statements1030917
Ref: option_mysqlbackup_open_files_limit1031036
Ref: option_mysqlbackup_search1031122
Ref: option_mysqlbackup_snapshots1031562
Ref: option_mysqlbackup_summary1031656
Ref: option_mysqlbackup_verbose1031741
Ref: option_mysqlbackup_version1031858
Node: mysqlbinlog1031922
Ref: option_mysqlbinlog_help1039306
Ref: option_mysqlbinlog_base64-output1039367
Ref: option_mysqlbinlog_character-sets-dir1041663
Ref: option_mysqlbinlog_database1041794
Ref: option_mysqlbinlog_debug1042410
Ref: option_mysqlbinlog_debug-check1042609
Ref: option_mysqlbinlog_debug-info1042695
Ref: option_mysqlbinlog_disable-log-bin1042816
Ref: option_mysqlbinlog_force-read1043478
Ref: option_mysqlbinlog_hexdump1043778
Ref: option_mysqlbinlog_host1043961
Ref: option_mysqlbinlog_local-load1044069
Ref: option_mysqlbinlog_offset1044217
Ref: option_mysqlbinlog_password1044288
Ref: option_mysqlbinlog_port1044756
Ref: option_mysqlbinlog_position1044867
Ref: option_mysqlbinlog_protocol1044947
Ref: option_mysqlbinlog_read-from-remote-server1045258
Ref: option_mysqlbinlog_result-file1045722
Ref: option_mysqlbinlog_server-id1045800
Ref: option_mysqlbinlog_set-charset1045911
Ref: option_mysqlbinlog_short-form1046079
Ref: option_mysqlbinlog_socket1046199
Ref: option_mysqlbinlog_start-datetime1046356
Ref: option_mysqlbinlog_start-position1046967
Ref: option_mysqlbinlog_stop-datetime1047174
Ref: option_mysqlbinlog_stop-position1047486
Ref: option_mysqlbinlog_to-last-log1047690
Ref: option_mysqlbinlog_user1048017
Ref: option_mysqlbinlog_verbose1048128
Ref: option_mysqlbinlog_version1048519
Ref: option_mysqlbinlog_write-binlog1048588
Ref: option_mysqlbinlog_open_files_limit1049251
Node: mysqlbinlog-hexdump1053196
Node: mysqlbinlog-row-events1062191
Node: mysqldumpslow1070585
Ref: option_mysqldumpslow_help1072843
Ref: option_mysqldumpslow_abstract1072898
Ref: option_mysqldumpslow_debug1072973
Ref: option_mysqldumpslow_grep1073021
Ref: option_mysqldumpslow_host1073108
Ref: option_mysqldumpslow_instance1073261
Ref: option_mysqldumpslow_lock1073376
Ref: option_mysqldumpslow_abstract-numbers1073437
Ref: option_mysqldumpslow_reverse1073511
Ref: option_mysqldumpslow_sort1073553
Ref: option_mysqldumpslow_top1073890
Ref: option_mysqldumpslow_verbose1073958
Node: mysqlhotcopy1074558
Ref: option_mysqlhotcopy_help1078368
Ref: option_mysqlhotcopy_addtodest1078429
Ref: option_mysqlhotcopy_allowold1078532
Ref: option_mysqlhotcopy_checkpoint1078634
Ref: option_mysqlhotcopy_chroot1078766
Ref: option_mysqlhotcopy_debug1078975
Ref: option_mysqlhotcopy_dryrun1079019
Ref: option_mysqlhotcopy_flushlog1079089
Ref: option_mysqlhotcopy_host1079155
Ref: option_mysqlhotcopy_keepold1079380
Ref: option_mysqlhotcopy_method1079456
Ref: option_mysqlhotcopy_noindices1079534
Ref: option_mysqlhotcopy_password1079758
Ref: option_mysqlhotcopy_port1080165
Ref: option_mysqlhotcopy_quiet1080278
Ref: option_mysqlhotcopy_record_log_pos1080336
Ref: option_mysqlhotcopy_regexp1080475
Ref: option_mysqlhotcopy_resetmaster1080580
Ref: option_mysqlhotcopy_resetslave1080660
Ref: option_mysqlhotcopy_socket1080747
Ref: option_mysqlhotcopy_suffix1080835
Ref: option_mysqlhotcopy_tmpdir1080905
Ref: option_mysqlhotcopy_user1080982
Node: mysql-convert-table-format1082153
Ref: option_mysql_convert_table_format_help1083138
Ref: option_mysql_convert_table_format_force1083193
Ref: option_mysql_convert_table_format_host1083247
Ref: option_mysql_convert_table_format_password1083326
Ref: option_mysql_convert_table_format_port1083719
Ref: option_mysql_convert_table_format_socket1083800
Ref: option_mysql_convert_table_format_type1083890
Ref: option_mysql_convert_table_format_user1084277
Ref: option_mysql_convert_table_format_verbose1084367
Ref: option_mysql_convert_table_format_version1084458
Node: mysql-find-rows1084516
Ref: option_mysql_find_rows_help1085791
Ref: option_mysql_find_rows_regexp1085863
Ref: option_mysql_find_rows_rows1085935
Ref: option_mysql_find_rows_skip-use-db1085992
Ref: option_mysql_find_rows_start_row1086076
Node: mysql-fix-extensions1086128
Node: mysql-setpermission1087080
Ref: option_mysql_setpermission_help1088337
Ref: option_mysql_setpermission_host1088392
Ref: option_mysql_setpermission_password1088471
Ref: option_mysql_setpermission_port1088864
Ref: option_mysql_setpermission_socket1088945
Ref: option_mysql_setpermission_user1089035
Node: mysql-waitpid1089120
Ref: option_mysql_waitpid_help1090202
Ref: option_mysql_waitpid_verbose1090269
Ref: option_mysql_waitpid_version1090397
Node: mysql-zap1090461
Ref: option_mysql_zap_help1091561
Ref: option_mysql_zap_force1091628
Ref: option_mysql_zap_test1091745
Node: programs-development1091833
Node: msql2mysql1093766
Node: mysql-config1094912
Ref: option_mysql_config_cflags1095367
Ref: option_mysql_config_include1095773
Ref: option_mysql_config_libmysqld-libs1095844
Ref: option_mysql_config_libs1095966
Ref: option_mysql_config_libs_r1096063
Ref: option_mysql_config_plugindir1096174
Ref: option_mysql_config_port1096316
Ref: option_mysql_config_socket1096402
Ref: option_mysql_config_version1096488
Node: my-print-defaults1098013
Ref: option_my_print_defaults_help1099043
Ref: option_my_print_defaults_config-file1099104
Ref: option_my_print_defaults_debug1099227
Ref: option_my_print_defaults_defaults-extra-file1099426
Ref: option_my_print_defaults_defaults-group-suffix1099620
Ref: option_my_print_defaults_no-defaults1099777
Ref: option_my_print_defaults_verbose1099836
Ref: option_my_print_defaults_version1099933
Node: resolve-stack-dump1099997
Ref: option_resolve_stack_dump_help1100868
Ref: option_resolve_stack_dump_numeric-dump-file1100929
Ref: option_resolve_stack_dump_symbols-file1101032
Ref: option_resolve_stack_dump_version1101116
Node: programs-miscellaneous1101180
Node: perror1101578
Ref: option_perror_help1102683
Ref: option_perror_silent1102760
Ref: option_perror_verbose1102833
Ref: option_perror_version1102943
Node: replace-utility1103007
Ref: option_replace_help1104543
Ref: option_replace_debug1104600
Ref: option_replace_silent1104649
Ref: option_replace_verbose1104726
Ref: option_replace_version1104810
Node: resolveip1104861
Ref: option_resolveip_help1105379
Ref: option_resolveip_silent1105456
Ref: option_resolveip_version1105520
Node: server-administration1105584
Node: mysqld-server1106588
Node: mysqld-option-tables1107850
Node: server-options1383873
Ref: option_mysqld_help1385980
Ref: option_mysqld_allow-suspicious-udfs1386215
Ref: option_mysqld_ansi1386849
Ref: option_mysqld_basedir1387173
Ref: option_mysqld_big-tables1387651
Ref: option_mysqld_bind-address1388390
Ref: option_mysqld_binlog-format1388893
Ref: option_mysqld_bootstrap1389525
Ref: option_mysqld_character-sets-dir1389965
Ref: option_mysqld_character-set-client-handshake1390467
Ref: option_mysqld_character-set-filesystem1390974
Ref: option_mysqld_character-set-server1391524
Ref: option_mysqld_chroot1392201
Ref: option_mysqld_collation-server1392702
Ref: option_mysqld_console1393200
Ref: option_mysqld_core-file1393624
Ref: option_mysqld_datadir1394849
Ref: option_mysqld_debug1395249
Ref: option_mysqld_debug-sync-timeout1396507
Ref: option_mysqld_default-character-set1397618
Ref: option_mysqld_default-collation1398060
Ref: option_mysqld_default-storage-engine1398529
Ref: option_mysqld_default-table-type1398801
Ref: option_mysqld_default-time-zone1399228
Ref: option_mysqld_delay-key-write1399709
Ref: option_mysqld_des-key-file1400836
Ref: option_mysqld_enable-named-pipe1401114
Ref: option_mysqld_enable-pstack1401254
Ref: option_mysqld_engine-condition-pushdown1401521
Ref: option_mysqld_event-scheduler1402804
Ref: option_mysqld_exit-info1403414
Ref: option_mysqld_external-locking1403809
Ref: option_mysqld_flush1404634
Ref: option_mysqld_gdb1405182
Ref: option_mysqld_general-log1405639
Ref: option_mysqld_init-file1406256
Ref: option_mysqld_language1406978
Ref: option_mysqld_large-pages1407639
Ref: option_mysqld_log1408665
Ref: option_mysqld_log-backup-output1409709
Ref: option_mysqld_log-error1411450
Ref: option_mysqld_log-isam1412040
Ref: option_mysqld_log-long-format1412323
Ref: option_mysqld_log-output1412974
Ref: option_mysqld_log-queries-not-using-indexes1414602
Ref: option_mysqld_log-short-format1415486
Ref: option_mysqld_log-slow-admin-statements1415883
Ref: option_mysqld_log-slow-queries1416337
Ref: option_mysqld_log-tc1417577
Ref: option_mysqld_log-tc-size1418115
Ref: option_mysqld_log-warnings1418634
Ref: option_mysqld_low-priority-updates1420112
Ref: option_mysqld_min-examined-row-limit1421068
Ref: option_mysqld_memlock1421850
Ref: option_mysqld_myisam-block-size1423366
Ref: option_mysqld_myisam-recover1423687
Ref: option_mysqld_old-passwords1425798
Ref: option_mysqld_old-style-user-limits1426406
Ref: option_mysqld_one-thread1426890
Ref: option_mysqld_open-files-limit1427333
Ref: option_mysqld_pid-file1428482
Ref: option_mysqld_plugin-load1429008
Ref: option_mysqld_port1430698
Ref: option_mysqld_port-open-timeout1431251
Ref: option_mysqld_safe-mode1431830
Ref: option_mysqld_safe-show-database1432024
Ref: option_mysqld_safe-user-create1432507
Ref: option_mysqld_secure-auth1433397
Ref: option_mysqld_secure-backup-file-priv1433896
Ref: option_mysqld_secure-file-priv1434612
Ref: option_mysqld_shared-memory1435444
Ref: option_mysqld_shared-memory-base-name1435573
Ref: option_mysqld_skip-concurrent-insert1435792
Ref: option_mysqld_skip-external-locking1436030
Ref: option_mysqld_skip-grant-tables1436329
Ref: option_mysqld_skip-host-cache1437198
Ref: option_mysqld_skip-innodb1437392
Ref: option_mysqld_skip-name-resolve1437592
Ref: option_mysqld_skip-networking1437845
Ref: option_mysqld_standalone1438374
Ref: option_mysqld_symbolic-links1438645
Ref: option_mysqld_skip-safemalloc1439614
Ref: option_mysqld_skip-show-database1440067
Ref: option_mysqld_skip-stack-trace1440919
Ref: option_mysqld_skip-thread-priority1441355
Ref: option_mysqld_slow-query-log1441688
Ref: option_mysqld_socket1442320
Ref: option_mysqld_sql-mode1443022
Ref: option_mysqld_sysdate-is-now1444091
Ref: option_mysqld_tc-heuristic-recover1444795
Ref: option_mysqld_temp-pool1445194
Ref: option_mysqld_transaction-isolation1445885
Ref: option_mysqld_tmpdir1446442
Ref: option_mysqld_user1447828
Ref: option_mysqld_verbose1449266
Ref: option_mysqld_version1449357
Node: server-system-variables1450426
Ref: sysvar_automatic_sp_privileges1482690
Ref: sysvar_backup_history_log1483444
Ref: sysvar_backup_history_log_file1484270
Ref: sysvar_backup_progress_log1484894
Ref: sysvar_backup_progress_log_file1485726
Ref: sysvar_back_log1486358
Ref: sysvar_backupdir1487733
Ref: sysvar_basedir1489362
Ref: sysvar_bulk_insert_buffer_size1489909
Ref: sysvar_character_set_client1490953
Ref: sysvar_character_set_connection1492393
Ref: sysvar_character_set_database1492724
Ref: sysvar_character_set_filesystem1493360
Ref: sysvar_character_set_results1494495
Ref: sysvar_character_set_server1494764
Ref: sysvar_character_set_system1495209
Ref: sysvar_character_sets_dir1495507
Ref: sysvar_collation_connection1495962
Ref: sysvar_collation_database1496210
Ref: sysvar_collation_server1496830
Ref: sysvar_completion_type1497251
Ref: sysvar_concurrent_insert1498405
Ref: sysvar_connect_timeout1499761
Ref: sysvar_datadir1500531
Ref: sysvar_date_format1500966
Ref: sysvar_datetime_format1501018
Ref: sysvar_debug1501074
Ref: sysvar_debug_sync1502415
Ref: sysvar_default_week_format1503862
Ref: sysvar_delay_key_write1504394
Ref: sysvar_delayed_insert_limit1506074
Ref: sysvar_delayed_insert_timeout1506985
Ref: sysvar_delayed_queue_size1507591
Ref: sysvar_div_precision_increment1508509
Ref: sysvar_event_scheduler1509650
Ref: sysvar_expire_logs_days1510427
Ref: sysvar_flush1511028
Ref: sysvar_flush_time1511700
Ref: sysvar_ft_boolean_syntax1512488
Ref: sysvar_ft_max_word_len1513692
Ref: sysvar_ft_min_word_len1514305
Ref: sysvar_ft_query_expansion_limit1514918
Ref: sysvar_ft_stopword_file1515505
Ref: sysvar_general_log1516410
Ref: sysvar_general_log_file1517218
Ref: sysvar_group_concat_max_len1517838
Ref: sysvar_have_compress1518575
Ref: sysvar_have_crypt1518765
Ref: sysvar_have_csv1518921
Ref: sysvar_have_dynamic_loading1519023
Ref: sysvar_have_geometry1519147
Ref: sysvar_have_innodb1519238
Ref: sysvar_have_openssl1519368
Ref: sysvar_have_partitioning1519438
Ref: sysvar_have_query_cache1519527
Ref: sysvar_have_rtree_keys1519636
Ref: sysvar_have_ssl1519782
Ref: sysvar_have_symlink1519883
Ref: sysvar_hostname1520135
Ref: sysvar_init_connect1520379
Ref: sysvar_init_file1521978
Ref: sysvar_interactive_timeout1522875
Ref: sysvar_join_buffer_size1523620
Ref: sysvar_join_cache_level1525070
Ref: sysvar_keep_files_on_create1527965
Ref: sysvar_key_buffer_size1529168
Ref: sysvar_key_cache_age_threshold1532344
Ref: sysvar_key_cache_block_size1533250
Ref: sysvar_key_cache_division_limit1533825
Ref: sysvar_language1534586
Ref: sysvar_large_files_support1535029
Ref: sysvar_large_pages1535262
Ref: sysvar_large_page_size1535795
Ref: sysvar_lc_time_names1536251
Ref: sysvar_license1536881
Ref: sysvar_local_infile1537120
Ref: sysvar_locked_in_memory1537423
Ref: sysvar_log1537639
Ref: sysvar_log_bin1537842
Ref: sysvar_log_bin_trust_function_creators1538023
Ref: sysvar_log_error1539330
Ref: sysvar_log_output1539723
Ref: sysvar_log_queries_not_using_indexes1540753
Ref: sysvar_log_slave_updates1541370
Ref: sysvar_log_slow_queries1541645
Ref: sysvar_log_warnings1542277
Ref: sysvar_long_query_time1543003
Ref: sysvar_low_priority_updates1544334
Ref: sysvar_lower_case_file_system1545181
Ref: sysvar_lower_case_table_names1545814
Ref: sysvar_max_allowed_packet1547089
Ref: sysvar_max_connect_errors1548837
Ref: sysvar_max_connections1549678
Ref: sysvar_max_delayed_threads1550775
Ref: sysvar_max_error_count1551780
Ref: sysvar_max_heap_table_size1552406
Ref: sysvar_max_insert_delayed_threads1553784
Ref: sysvar_max_join_size1554051
Ref: sysvar_max_length_for_sort_data1555519
Ref: sysvar_max_prepared_stmt_count1556134
Ref: sysvar_max_relay_log_size1557261
Ref: sysvar_max_seeks_for_key1558377
Ref: sysvar_max_sort_length1559441
Ref: sysvar_max_sp_recursion_depth1560067
Ref: sysvar_max_tmp_tables1561021
Ref: sysvar_max_user_connections1561749
Ref: sysvar_max_write_lock_count1562607
Ref: sysvar_min_examined_row_limit1563348
Ref: sysvar_myisam_data_pointer_size1564075
Ref: sysvar_myisam_max_sort_file_size1564797
Ref: sysvar_myisam_recover_options1565811
Ref: sysvar_myisam_repair_threads1566040
Ref: sysvar_myisam_sort_buffer_size1566935
Ref: sysvar_myisam_stats_method1568047
Ref: sysvar_myisam_use_mmap1569412
Ref: sysvar_named_pipe1569885
Ref: sysvar_net_buffer_length1570136
Ref: sysvar_net_read_timeout1571363
Ref: sysvar_net_retry_count1572384
Ref: sysvar_net_write_timeout1573192
Ref: sysvar_new1573885
Ref: sysvar_old1574435
Ref: sysvar_old_passwords1575313
Ref: sysvar_one_shot1575822
Ref: sysvar_open_files_limit1575962
Ref: sysvar_optimizer_prune_level1576791
Ref: sysvar_optimizer_search_depth1577554
Ref: sysvar_optimizer_switch1578633
Ref: sysvar_optimizer_use_mrr1581319
Ref: sysvar_pid_file1582693
Ref: sysvar_plugin_dir1583152
Ref: sysvar_port1583595
Ref: sysvar_preload_buffer_size1584085
Ref: sysvar_protocol_version1584611
Ref: sysvar_query_alloc_block_size1584873
Ref: sysvar_query_cache_limit1585736
Ref: sysvar_query_cache_min_res_unit1586450
Ref: sysvar_query_cache_size1587303
Ref: sysvar_query_cache_type1588593
Ref: sysvar_query_cache_wlock_invalidate1589936
Ref: sysvar_query_prealloc_size1590887
Ref: sysvar_range_alloc_block_size1591890
Ref: sysvar_read_buffer_size1592475
Ref: sysvar_read_only1593578
Ref: sysvar_read_rnd_buffer_size1595715
Ref: sysvar_relay_log_purge1596931
Ref: sysvar_relay_log_space_limit1597478
Ref: sysvar_report_host1598172
Ref: sysvar_report_password1598285
Ref: sysvar_report_port1598406
Ref: sysvar_report_user1598519
Ref: sysvar_rpl_semi_sync_master_enabled1598632
Ref: sysvar_rpl_semi_sync_master_reply_log_file_pos1598994
Ref: sysvar_rpl_semi_sync_master_timeout1599210
Ref: sysvar_rpl_semi_sync_master_trace_level1599609
Ref: sysvar_rpl_semi_sync_slave_enabled1599818
Ref: sysvar_rpl_semi_sync_slave_trace_level1600177
Ref: sysvar_secure_auth1600384
Ref: sysvar_secure_backup_file_priv1601343
Ref: sysvar_secure_file_priv1601726
Ref: sysvar_server_id1602607
Ref: sysvar_shared_memory1603314
Ref: sysvar_shared_memory_base_name1603556
Ref: sysvar_skip_external_locking1603979
Ref: sysvar_skip_networking1604124
Ref: sysvar_skip_show_database1604525
Ref: sysvar_slow_launch_time1605311
Ref: sysvar_slow_query_log1605832
Ref: sysvar_slow_query_log_file1606295
Ref: sysvar_socket1606926
Ref: sysvar_sort_buffer_size1607723
Ref: sysvar_sql_mode1608752
Ref: sysvar_sql_select_limit1609840
Ref: sysvar_ssl_ca1611026
Ref: sysvar_ssl_capath1611422
Ref: sysvar_ssl_cert1611873
Ref: sysvar_ssl_cipher1612315
Ref: sysvar_ssl_key1612735
Ref: sysvar_storage_engine1613164
Ref: sysvar_sync_frm1613520
Ref: sysvar_system_time_zone1614109
Ref: sysvar_table_definition_cache1615022
Ref: sysvar_table_lock_wait_timeout1616113
Ref: sysvar_table_open_cache1616630
Ref: sysvar_thread_cache_size1617623
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Ref: sysvar_thread_handling1619580
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Ref: sysvar_time_zone1622871
Ref: sysvar_timed_mutexes1623541
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Ref: sysvar_tmpdir1625360
Ref: sysvar_transaction_alloc_block_size1626884
Ref: sysvar_transaction_prealloc_size1627569
Ref: sysvar_tx_isolation1628855
Ref: sysvar_updatable_views_with_limit1629658
Ref: sysvar_version_comment1631011
Ref: sysvar_version_compile_machine1631214
Ref: sysvar_version_compile_os1631315
Ref: sysvar_wait_timeout1631568
Node: server-session-variables1632924
Ref: sysvar_autocommit1635754
Ref: sysvar_backup_wait_timeout1636348
Ref: sysvar_big_tables1636668
Ref: sysvar_error_count1637255
Ref: sysvar_foreign_key_checks1637429
Ref: sysvar_identity1638385
Ref: sysvar_insert_id1638625
Ref: sysvar_last_insert_id1638852
Ref: sysvar_profiling1639178
Ref: sysvar_profiling_history_size1639532
Ref: sysvar_rand_seed11639860
Ref: sysvar_rand_seed21640554
Ref: sysvar_sql_auto_is_null1640618
Ref: sysvar_sql_big_selects1640923
Ref: sysvar_sql_buffer_result1641515
Ref: sysvar_sql_log_bin1641846
Ref: sysvar_sql_log_off1642036
Ref: sysvar_sql_log_update1642234
Ref: sysvar_sql_notes1642325
Ref: sysvar_sql_quote_show_create1642680
Ref: sysvar_sql_safe_updates1643115
Ref: sysvar_sql_warnings1643541
Ref: sysvar_timestamp1643776
Ref: sysvar_unique_checks1644407
Ref: sysvar_warning_count1645020
Node: using-system-variables1645214
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Ref: statvar_Aborted_clients1718683
Ref: statvar_Aborted_connects1718867
Ref: statvar_Binlog_cache_disk_use1719001
Ref: statvar_Binlog_cache_use1719235
Ref: statvar_Bytes_received1719341
Ref: statvar_Bytes_sent1719418
Ref: statvar_Com_xxx1719485
Ref: statvar_Compression1721852
Ref: statvar_Connections1721962
Ref: statvar_Created_tmp_disk_tables1722069
Ref: statvar_Created_tmp_files1722216
Ref: statvar_Created_tmp_tables1722311
Ref: statvar_Delayed_errors1722629
Ref: statvar_Delayed_insert_threads1722799
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Ref: statvar_Flush_commands1723025
Ref: statvar_Handler_commit1723113
Ref: statvar_Handler_delete1723203
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Ref: statvar_Handler_read_first1723389
Ref: statvar_Handler_read_key1723655
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Ref: statvar_Handler_read_prev1724075
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Ref: statvar_Handler_read_rnd_next1724569
Ref: statvar_Handler_rollback1724892
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Ref: statvar_Innodb_buffer_pool_pages_data1725386
Ref: statvar_Innodb_buffer_pool_pages_dirty1725485
Ref: statvar_Innodb_buffer_pool_pages_flushed1725568
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Ref: statvar_Innodb_buffer_pool_read_ahead_rnd1726548
Ref: statvar_Innodb_buffer_pool_read_ahead_seq1726745
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Ref: statvar_Innodb_buffer_pool_reads1727024
Ref: statvar_Innodb_buffer_pool_wait_free1727184
Ref: statvar_Innodb_buffer_pool_write_requests1727592
Ref: statvar_Innodb_data_fsyncs1727693
Ref: statvar_Innodb_data_pending_fsyncs1727770
Ref: statvar_Innodb_data_pending_reads1727864
Ref: statvar_Innodb_data_pending_writes1727942
Ref: statvar_Innodb_data_read1728022
Ref: statvar_Innodb_data_reads1728096
Ref: statvar_Innodb_data_writes1728161
Ref: statvar_Innodb_data_written1728228
Ref: statvar_Innodb_dblwr_pages_written1728308
Ref: statvar_Innodb_dblwr_writes1728454
Ref: statvar_Innodb_log_waits1728585
Ref: statvar_Innodb_log_write_requests1728740
Ref: statvar_Innodb_log_writes1728815
Ref: statvar_Innodb_os_log_fsyncs1728895
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Ref: statvar_Innodb_os_log_pending_writes1729081
Ref: statvar_Innodb_os_log_written1729164
Ref: statvar_Innodb_page_size1729246
Ref: statvar_Innodb_pages_created1729432
Ref: statvar_Innodb_pages_read1729497
Ref: statvar_Innodb_pages_written1729556
Ref: statvar_Innodb_row_lock_current_waits1729621
Ref: statvar_Innodb_row_lock_time1729718
Ref: statvar_Innodb_row_lock_time_avg1729816
Ref: statvar_Innodb_row_lock_time_max1729913
Ref: statvar_Innodb_row_lock_waits1730010
Ref: statvar_Innodb_rows_deleted1730100
Ref: statvar_Innodb_rows_inserted1730184
Ref: statvar_Innodb_rows_read1730270
Ref: statvar_Innodb_rows_updated1730348
Ref: statvar_Key_blocks_not_flushed1730430
Ref: statvar_Key_blocks_unused1730572
Ref: statvar_Key_blocks_used1730810
Ref: statvar_Key_read_requests1731011
Ref: statvar_Key_reads1731103
Ref: statvar_Key_write_requests1731354
Ref: statvar_Key_writes1731446
Ref: statvar_Last_query_cost1731526
Ref: statvar_Max_used_connections1732087
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Ref: statvar_Open_files1732332
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Ref: statvar_Prepared_stmt_count1733421
Ref: statvar_Qcache_free_blocks1733603
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Ref: statvar_Qcache_queries_in_cache1734174
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Ref: statvar_Rpl_semi_sync_master_net_avg_wait_time1735062
Ref: statvar_Rpl_semi_sync_master_net_wait_time1735277
Ref: statvar_Rpl_semi_sync_master_net_waits1735488
Ref: statvar_Rpl_semi_sync_master_no_times1735695
Ref: statvar_Rpl_semi_sync_master_no_tx1735901
Ref: statvar_Rpl_semi_sync_master_status1736165
Ref: statvar_Rpl_semi_sync_master_timefunc_failures1736672
Ref: statvar_Rpl_semi_sync_master_tx_avg_wait_time1736887
Ref: statvar_Rpl_semi_sync_master_tx_wait_time1737101
Ref: statvar_Rpl_semi_sync_master_tx_waits1737311
Ref: statvar_Rpl_semi_sync_master_wait_pos_backtraverse1737517
Ref: statvar_Rpl_semi_sync_master_wait_sessions1737736
Ref: statvar_Rpl_semi_sync_master_yes_tx1737947
Ref: statvar_Rpl_semi_sync_slave_status1738208
Ref: statvar_Rpl_status1738568
Ref: statvar_Select_full_join1738653
Ref: statvar_Select_full_range_join1738852
Ref: statvar_Select_range1738957
Ref: statvar_Select_range_check1739119
Ref: statvar_Select_scan1739310
Ref: statvar_Slave_heartbeat_period1739398
Ref: statvar_Slave_open_temp_tables1739565
Ref: statvar_Slave_received_heartbeats1739685
Ref: statvar_Slave_retried_transactions1740005
Ref: statvar_Slave_running1740156
Ref: statvar_Slow_launch_threads1741095
Ref: statvar_Slow_queries1741221
Ref: statvar_Sort_merge_passes1741357
Ref: statvar_Sort_range1741574
Ref: statvar_Sort_rows1741649
Ref: statvar_Sort_scan1741701
Ref: statvar_Ssl_accept_renegotiates1741784
Ref: statvar_Ssl_accepts1741884
Ref: statvar_Ssl_callback_cache_hits1741951
Ref: statvar_Ssl_cipher1742025
Ref: statvar_Ssl_cipher_list1742107
Ref: statvar_Ssl_client_connects1742172
Ref: statvar_Ssl_connect_renegotiates1742271
Ref: statvar_Ssl_ctx_verify_depth1742402
Ref: statvar_Ssl_ctx_verify_mode1742527
Ref: statvar_Ssl_default_timeout1742597
Ref: statvar_Ssl_finished_accepts1742657
Ref: statvar_Ssl_finished_connects1742749
Ref: statvar_Ssl_session_cache_hits1742860
Ref: statvar_Ssl_session_cache_misses1742936
Ref: statvar_Ssl_session_cache_mode1743016
Ref: statvar_Ssl_session_cache_overflows1743082
Ref: statvar_Ssl_session_cache_size1743168
Ref: statvar_Ssl_session_cache_timeouts1743234
Ref: statvar_Ssl_sessions_reused1743318
Ref: statvar_Ssl_used_session_cache_entries1743406
Ref: statvar_Ssl_verify_depth1743498
Ref: statvar_Ssl_verify_mode1743586
Ref: statvar_Ssl_version1743672
Ref: statvar_Table_locks_immediate1743723
Ref: statvar_Table_locks_waited1743847
Ref: statvar_Tc_log_max_pages_used1744158
Ref: statvar_Tc_log_page_size1745004
Ref: statvar_Tc_log_page_waits1745284
Ref: statvar_Threads_cached1745853
Ref: statvar_Threads_connected1745926
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Ref: statvar_Uptime1746335
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Node: server-sql-mode1746553
Ref: sqlmode_allow_invalid_dates1750011
Ref: sqlmode_ansi_quotes1750963
Ref: sqlmode_error_for_division_by_zero1751321
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Ref: sqlmode_ignore_space1752375
Ref: sqlmode_no_auto_create_user1753391
Ref: sqlmode_no_auto_value_on_zero1753594
Ref: sqlmode_no_backslash_escapes1754611
Ref: sqlmode_no_dir_in_create1754827
Ref: sqlmode_no_engine_substitution1755006
Ref: sqlmode_no_field_options1755814
Ref: sqlmode_no_key_options1756034
Ref: sqlmode_no_table_options1756251
Ref: sqlmode_no_unsigned_subtraction1756489
Ref: sqlmode_no_zero_date1758623
Ref: sqlmode_no_zero_in_date1758853
Ref: sqlmode_only_full_group_by1759257
Ref: sqlmode_pad_char_to_full_length1759764
Ref: sqlmode_pipes_as_concat1761134
Ref: sqlmode_real_as_float1761272
Ref: sqlmode_strict_all_tables1761495
Ref: sqlmode_strict_trans_tables1761638
Ref: sqlmode_ansi1764719
Ref: sqlmode_db21765509
Ref: sqlmode_maxdb1765655
Ref: sqlmode_mssql1765831
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Ref: sqlmode_mysql401766060
Ref: sqlmode_oracle1766140
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Ref: sqlmode_traditional1766470
Node: server-side-help-support1766648
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Ref: option_mysqld_local-infile1856994
Ref: option_mysqld_ssl_xxxx1862121
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Ref: priv_create-tablespace1878522
Ref: priv_create-temporary-tables1878683
Ref: priv_create-user1878834
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Ref: priv_event1879688
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Ref: option_general_ssl2009591
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Ref: option_general_ssl-key2012068
Ref: option_general_ssl-verify-server-cert2012182
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Node: func-op-summary-ref2977803
Node: non-typed-operators2996859
Node: operator-precedence2999332
Node: type-conversion3000512
Node: comparison-operators3006707
Ref: operator_equal3009637
Ref: operator_equal-to3009950
Ref: operator_not-equal3010368
Ref: operator_less-than-or-equal3010596
Ref: operator_less-than3010692
Ref: operator_greater-than-or-equal3010775
Ref: operator_greater-than3010872
Ref: operator_is3010958
Ref: operator_is-not3011186
Ref: operator_is-null3011435
Ref: operator_is-not-null3012475
Ref: operator_between3012641
Ref: operator_not-between3013867
Ref: function_coalesce3013965
Ref: function_greatest3014240
Ref: function_in3014711
Ref: function_not-in3016292
Ref: function_isnull3016380
Ref: function_interval3016892
Ref: function_least3017436
Node: logical-operators3018840
Ref: operator_not3019755
Ref: operator_and3020283
Ref: operator_or3020751
Ref: operator_xor3021340
Node: control-flow-functions3021855
Ref: operator_case3022287
Ref: function_if3023855
Ref: function_ifnull3025176
Ref: function_nullif3026502
Node: string-functions3026887
Ref: function_ascii3032297
Ref: function_bin3032734
Ref: function_bit-length3033019
Ref: function_char3033165
Ref: function_char-length3035103
Ref: function_character-length3035393
Ref: function_concat3035485
Ref: function_concat-ws3036467
Ref: function_elt3037250
Ref: function_export-set3037647
Ref: function_field3038364
Ref: function_find-in-set3039080
Ref: function_format3039805
Ref: function_hex3040264
Ref: function_insert3040914
Ref: function_instr3041648
Ref: function_lcase3042144
Ref: function_left3042208
Ref: function_length3042412
Ref: function_load-file3042752
Ref: function_locate3043650
Ref: function_lower3044327
Ref: function_lpad3045344
Ref: function_ltrim3045696
Ref: function_make-set3045898
Ref: function_mid3046583
Ref: function_octet-length3046677
Ref: function_ord3046756
Ref: function_position3047266
Ref: function_quote3047370
Ref: function_repeat3047930
Ref: function_replace3048218
Ref: function_reverse3048586
Ref: function_right3048788
Ref: function_rpad3049034
Ref: function_rtrim3049426
Ref: function_soundex3049630
Ref: operator_sounds-like3051223
Ref: function_space3051317
Ref: function_substr3051457
Ref: function_substring3051615
Ref: function_substring-index3053042
Ref: function_trim3053735
Ref: function_ucase3054444
Ref: function_unhex3054508
Ref: function_upper3056152
Ref: function_weight-string3056716
Node: string-comparison-functions3064741
Ref: operator_like3065480
Ref: operator_not-like3069391
Ref: function_strcmp3070457
Node: regexp3071078
Ref: operator_not-regexp3072173
Ref: operator_regexp3072275
Node: numeric-functions3085363
Node: arithmetic-functions3088453
Ref: operator_plus3090443
Ref: operator_minus3090523
Ref: operator_unary-minus3090607
Ref: operator_times3090984
Ref: operator_divide3091495
Ref: operator_div3091853
Ref: operator_mod3092494
Node: mathematical-functions3092681
Ref: function_abs3095382
Ref: function_acos3095635
Ref: function_asin3095974
Ref: function_atan3096793
Ref: function_atan23097033
Ref: function_ceil3097440
Ref: function_ceiling3097502
Ref: function_conv3097892
Ref: function_cos3098730
Ref: function_cot3098866
Ref: function_crc323099046
Ref: function_degrees3099449
Ref: function_exp3099666
Ref: function_floor3100060
Ref: function_ln3100931
Ref: function_log3101331
Ref: function_log23102180
Ref: function_log103102525
Ref: function_mod3102827
Ref: function_oct3103459
Ref: function_pi3103741
Ref: function_pow3104071
Ref: function_power3104263
Ref: function_radians3104320
Ref: function_rand3104528
Ref: function_round3107974
Ref: function_sign3110376
Ref: function_sin3110688
Ref: function_sqrt3110904
Ref: function_tan3111168
Ref: function_truncate3111397
Node: date-and-time-functions3112102
Ref: function_adddate3118669
Ref: function_addtime3119426
Ref: function_convert-tz3119838
Ref: function_curdate3120854
Ref: function_current-date3121178
Ref: function_curtime3121290
Ref: function_current-time3121674
Ref: function_current-timestamp3121786
Ref: function_date3121919
Ref: function_datediff3122097
Ref: function_date-add3122548
Ref: function_date-format3129987
Ref: function_date-sub3133663
Ref: function_day3133750
Ref: function_dayname3133816
Ref: function_dayofmonth3134100
Ref: function_dayofweek3134366
Ref: function_dayofyear3134618
Ref: function_extract3134788
Ref: function_from-days3135424
Ref: function_from-unixtime3135779
Ref: function_get-format3137110
Ref: function_hour3138965
Ref: function_last-day3139358
Ref: function_localtime3139869
Ref: function_localtimestamp3139965
Ref: function_makedate3140081
Ref: function_maketime3140527
Ref: function_microsecond3140730
Ref: function_minute3141058
Ref: function_month3141220
Ref: function_monthname3141491
Ref: function_now3141782
Ref: function_period-add3143679
Ref: function_period-diff3143952
Ref: function_quarter3144247
Ref: function_second3144414
Ref: function_sec-to-time3144565
Ref: function_str-to-date3145035
Ref: function_subdate3146625
Ref: function_subtime3147390
Ref: function_sysdate3147835
Ref: function_time3149949
Ref: function_timediff3150256
Ref: function_timestamp3150782
Ref: function_timestampadd3151302
Ref: function_timestampdiff3152190
Ref: function_time-format3153207
Ref: function_time-to-sec3153803
Ref: function_to-days3154037
Ref: function_unix-timestamp3155002
Ref: function_utc-date3157862
Ref: function_utc-time3158161
Ref: function_utc-timestamp3158466
Ref: function_week3158838
Ref: function_weekday3161442
Ref: function_weekofyear3161710
Ref: function_year3161989
Ref: function_yearweek3162177
Node: mysql-calendar3162748
Node: fulltext-search3164666
Ref: function_match3165227
Node: fulltext-natural-language3168256
Node: fulltext-boolean3179168
Node: fulltext-query-expansion3185653
Node: fulltext-stopwords3188801
Node: fulltext-restrictions3196285
Node: fulltext-fine-tuning3197981
Node: cast-functions3204856
Ref: operator_binary3205266
Ref: function_cast3206256
Ref: function_convert3206466
Node: xml-functions3211162
Ref: function_extractvalue3217443
Ref: function_updatexml3223225
Node: other-functions3243526
Node: bit-functions3247786
Ref: operator_bitwise-or3248453
Ref: operator_bitwise-and3248588
Ref: operator_bitwise-xor3248724
Ref: operator_left-shift3248966
Ref: operator_right-shift3249327
Ref: operator_bitwise-invert3249689
Ref: function_bit-count3249827
Node: encryption-functions3249997
Ref: function_aes-decrypt3251957
Ref: function_aes-encrypt3252180
Ref: function_compress3253670
Ref: function_decode3255159
Ref: function_encode3255334
Ref: function_des-decrypt3255646
Ref: function_des-encrypt3256551
Ref: function_encrypt3258613
Ref: function_md53259449
Ref: function_old-password3260131
Ref: function_password3260594
Ref: function_sha13261610
Ref: function_sha23262334
Ref: function_uncompress3263283
Ref: function_uncompressed-length3263790
Node: information-functions3264015
Ref: function_benchmark3265600
Ref: function_charset3268043
Ref: function_coercibility3268349
Ref: function_collation3269323
Ref: function_connection-id3269569
Ref: function_current-user3269826
Ref: function_database3271196
Ref: function_found-rows3271720
Ref: function_last-insert-id3275787
Ref: function_row-count3283400
Ref: function_schema3284365
Ref: function_session-user3284434
Ref: function_system-user3284508
Ref: function_user3284580
Ref: function_version3285113
Node: miscellaneous-functions3285411
Ref: function_default3286818
Ref: function_get-lock3287219
Ref: function_inet-aton3289952
Ref: function_inet-ntoa3290940
Ref: function_is-free-lock3291203
Ref: function_is-used-lock3291473
Ref: function_master-pos-wait3291689
Ref: function_name-const3292673
Ref: function_release-lock3293378
Ref: function_sleep3293905
Ref: function_uuid3294142
Ref: function_uuid-short3296730
Ref: function_values3297792
Node: group-by-functions-and-modifiers3298600
Node: group-by-functions3299061
Ref: function_avg3301831
Ref: function_bit-and3302197
Ref: function_bit-or3302552
Ref: function_bit-xor3302780
Ref: function_count3303010
Ref: function_count-distinct3304258
Ref: function_group-concat3304753
Ref: function_max3306858
Ref: function_min3307734
Ref: function_std3308610
Ref: function_stddev3308863
Ref: function_stddev-pop3309138
Ref: function_stddev-samp3309415
Ref: function_sum3309602
Ref: function_var-pop3309878
Ref: function_var-samp3310222
Ref: function_variance3310418
Node: group-by-modifiers3310666
Node: group-by-hidden-columns3318623
Node: spatial-extensions3321380
Node: gis-introduction3323253
Node: opengis-geometry-model3325558
Node: gis-geometry-class-hierarchy3326838
Node: gis-class-geometry3329490
Node: gis-class-point3333053
Node: gis-class-curve3333686
Node: gis-class-linestring3334535
Node: gis-class-surface3335222
Node: gis-class-polygon3335946
Node: gis-class-geometrycollection3337173
Node: gis-class-multipoint3338006
Node: gis-class-multicurve3338781
Node: gis-class-multilinestring3339744
Node: gis-class-multisurface3340183
Node: gis-class-multipolygon3340766
Node: supported-spatial-data-formats3342241
Node: gis-wkt-format3342925
Node: gis-wkb-format3344399
Node: creating-a-spatially-enabled-mysql-database3346159
Node: mysql-spatial-datatypes3346900
Node: creating-spatial-values3347888
Node: gis-wkt-functions3348566
Ref: function_geomcollfromtext3349225
Ref: function_geomfromtext3349400
Ref: function_linefromtext3349556
Ref: function_mlinefromtext3349706
Ref: function_mpointfromtext3349867
Ref: function_mpolyfromtext3350019
Ref: function_pointfromtext3350174
Ref: function_polyfromtext3350281
Ref: function_bdmpolyfromtext3350703
Ref: function_bdpolyfromtext3350899
Node: gis-wkb-functions3351084
Ref: function_geomcollfromwkb3351782
Ref: function_geomfromwkb3351955
Ref: function_linefromwkb3352109
Ref: function_mlinefromwkb3352257
Ref: function_mpointfromwkb3352416
Ref: function_mpolyfromwkb3352566
Ref: function_pointfromwkb3352719
Ref: function_polyfromwkb3352825
Ref: function_bdmpolyfromwkb3353233
Ref: function_bdpolyfromwkb3353428
Node: gis-mysql-specific-functions3353612
Ref: function_geometrycollection3354308
Ref: function_linestring3354501
Ref: function_multilinestring3354778
Ref: function_multipoint3354978
Ref: function_multipolygon3355153
Ref: function_point3355353
Ref: function_polygon3355427
Node: creating-spatial-columns3355688
Node: populating-spatial-columns3356635
Node: fetching-spatial-data3359583
Node: analysing-spatial-information3360508
Node: functions-to-convert-geometries-between-formats3362194
Ref: function_asbinary3362606
Ref: function_astext3362793
Node: geometry-property-functions3363818
Node: general-geometry-property-functions3364911
Ref: function_dimension3365269
Ref: function_envelope3365843
Ref: function_geometrytype3366558
Ref: function_srid3367108
Ref: function_boundary3367853
Ref: function_isempty3367979
Ref: function_issimple3368189
Node: point-property-functions3368817
Ref: function_x3369146
Ref: function_y3369518
Node: linestring-property-functions3369885
Ref: function_endpoint3370290
Ref: function_glength3370760
Ref: function_numpoints3371316
Ref: function_pointn3371737
Ref: function_startpoint3372229
Ref: function_isring3372812
Node: multilinestring-property-functions3373088
Ref: function_isclosed3374030
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Ref: function_area3374914
Ref: function_exteriorring3375394
Ref: function_interiorringn3375956
Ref: function_numinteriorrings3376582
Node: multipolygon-property-functions3377107
Ref: function_centroid3378047
Node: geometrycollection-property-functions3378349
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Node: spatial-operators3380981
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Ref: function_convexhull3381569
Ref: function_difference3381679
Ref: function_intersection3381811
Ref: function_symdifference3381948
Ref: function_union3382093
Node: functions-for-testing-spatial-relations-between-geometric-objects3382210
Node: relations-on-geometry-mbr3382741
Ref: function_mbrcontains3383305
Ref: function_mbrdisjoint3384012
Ref: function_mbrequal3384183
Ref: function_mbrintersects3384332
Ref: function_mbroverlaps3384483
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Ref: function_mbrwithin3385175
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Ref: function_crosses3386927
Ref: function_disjoint3387554
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Ref: function_equals3387821
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Ref: function_within3388909
Node: optimizing-spatial-analysis3389054
Node: creating-spatial-indexes3390606
Node: using-a-spatial-index3393069
Node: mysql-gis-conformance-and-compatibility3399897
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Node: precision-math-numbers3403465
Node: precision-math-decimal-changes3405125
Node: precision-math-expressions3409025
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Node: precision-math-examples3415803
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Node: sql-syntax-data-definition3425010
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Node: comparisons-using-subqueries3768187
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Ref: sysvar_innodb_autoextend_increment4388926
Ref: sysvar_innodb_autoinc_lock_mode4389112
Ref: sysvar_innodb_buffer_pool_size4389501
Ref: sysvar_innodb_checksums4389992
Ref: sysvar_innodb_commit_concurrency4390391
Ref: sysvar_innodb_concurrency_tickets4390585
Ref: sysvar_innodb_data_file_path4391307
Ref: sysvar_innodb_data_home_dir4392198
Ref: sysvar_innodb_doublewrite4392468
Ref: sysvar_innodb_fast_shutdown4392851
Ref: sysvar_innodb_file_io_threads4393504
Ref: sysvar_innodb_file_per_table4393803
Ref: sysvar_innodb_flush_log_at_trx_commit4394163
Ref: sysvar_innodb_flush_method4396530
Ref: sysvar_innodb_force_recovery4397715
Ref: sysvar_innodb_lock_wait_timeout4398159
Ref: sysvar_innodb_locks_unsafe_for_binlog4399257
Ref: sysvar_innodb_log_buffer_size4406494
Ref: sysvar_innodb_log_file_size4406913
Ref: sysvar_innodb_log_files_in_group4407412
Ref: sysvar_innodb_log_group_home_dir4407600
Ref: sysvar_innodb_max_dirty_pages_pct4407859
Ref: sysvar_innodb_max_purge_lag4408142
Ref: sysvar_innodb_mirrored_log_groups4409307
Ref: sysvar_innodb_open_files4409450
Ref: sysvar_innodb_rollback_on_timeout4409936
Ref: sysvar_innodb_stats_on_metadata4410262
Ref: sysvar_innodb_support_xa4411078
Ref: sysvar_innodb_sync_spin_loops4411675
Ref: sysvar_innodb_table_locks4411844
Ref: sysvar_innodb_thread_concurrency4412256
Ref: sysvar_innodb_thread_sleep_delay4413141
Node: using-innodb-tables4414031
Node: innodb-transactions-with-different-apis4416061
Node: converting-tables-to-innodb4418191
Node: innodb-auto-increment-handling4421262
Node: innodb-auto-increment-traditional4422157
Node: innodb-auto-increment-configurable4426213
Node: innodb-foreign-key-constraints4443836
Node: innodb-and-mysql-replication4460388
Node: adding-and-removing4464990
Node: innodb-backup4469048
Node: forcing-recovery4474738
Node: innodb-checkpoints4477937
Node: moving4479642
Node: innodb-transaction-model4481258
Node: innodb-lock-modes4485239
Node: innodb-consistent-read4490335
Node: innodb-locking-reads4495339
Node: innodb-record-level-locks4499859
Node: innodb-next-key-locking4504335
Node: innodb-locks-set4507642
Node: innodb-implicit-commit4516797
Node: innodb-deadlock-detection4517647
Node: innodb-deadlocks4519439
Node: innodb-multi-versioning4522993
Node: innodb-table-and-index4526532
Node: innodb-index-types4527557
Node: innodb-physical-structure4529398
Node: innodb-insert-buffering4530223
Node: innodb-adaptive-hash4532202
Node: innodb-physical-record4533335
Node: file-space-management4538847
Node: innodb-disk-io4539248
Node: innodb-file-space4540734
Node: innodb-file-defragmenting4544323
Node: innodb-error-handling4546057
Node: innodb-error-codes4549136
Node: operating-system-error-codes4550794
Node: innodb-tuning-troubleshooting4556264
Node: innodb-tuning4556825
Node: innodb-monitors4564823
Node: innodb-general-monitor4570899
Node: innodb-tablespace-monitor4584100
Node: innodb-table-monitor4589017
Node: innodb-troubleshooting4598341
Node: innodb-troubleshooting-datadict4600188
Node: innodb-restrictions4603792
Node: se-falcon4613515
Node: se-falcon-features4616762
Node: se-falcon-configuration4619018
Ref: option_mysqld_falcon4631556
Ref: option_mysqld_skip-falcon4631826
Ref: sysvar_falcon_checkpoint_schedule4632033
Ref: sysvar_falcon_checksums4633644
Ref: sysvar_falcon_consistent_read4634126
Ref: sysvar_falcon_debug_mask4635530
Ref: sysvar_falcon_debug_server4637846
Ref: sysvar_falcon_disable_fsync4638362
Ref: sysvar_falcon_gopher_threads4639084
Ref: sysvar_falcon_index_chill_threshold4639645
Ref: sysvar_falcon_initial_allocation4641281
Ref: sysvar_falcon_io_threads4641983
Ref: sysvar_falcon_max_transaction_backlog4642492
Ref: sysvar_falcon_large_blob_threshold4643262
Ref: option_mysqld_falcon_lock_wait_timeout4644002
Ref: sysvar_falcon_page_cache_size4644941
Ref: sysvar_falcon_page_size4645516
Ref: sysvar_falcon_record_chill_threshold4646836
Ref: sysvar_falcon_record_memory_max4648381
Ref: sysvar_falcon_record_scavenge_floor4649091
Ref: sysvar_falcon_record_scavenge_threshold4649989
Ref: sysvar_falcon_scavenge_schedule4650794
Ref: sysvar_falcon_serial_log_buffers4651420
Ref: sysvar_falcon_serial_log_dir4652075
Ref: sysvar_falcon_serial_log_priority4652717
Ref: sysvar_falcon_support_xa4653243
Ref: sysvar_falcon_use_deferred_index_hash4653905
Ref: sysvar_falcon_use_sectorcache4654475
Ref: sysvar_falcon_use_supernodes4655141
Node: se-falcon-createdb4656952
Node: se-falcon-createtable4658751
Node: se-falcon-stats4661044
Node: se-falcon-principles4667374
Node: se-falcon-principles-tablespace4669053
Node: se-falcon-principles-logging4670316
Node: se-falcon-principles-logging-rollback4672717
Node: se-falcon-principles-logging-groupcommit4673268
Node: se-falcon-principles-recovery4675105
Node: se-falcon-principles-caches4676111
Node: se-falcon-principles-threads4679662
Node: se-falcon-principles-compression4680254
Node: se-falcon-principles-recordslot4680652
Node: se-falcon-limits4681184
Node: se-falcon-roadmap4686253
Node: merge-storage-engine4686697
Node: merge-table-problems4696422
Node: memory-storage-engine4703469
Node: example-storage-engine4714634
Node: federated-storage-engine4715986
Node: federated-description4717285
Ref: figure-se-federated-structure4718953
Node: federated-create4720229
Node: federated-create-connection4722451
Node: federated-create-server4725072
Node: federated-usagenotes4728341
Node: federated-storage-engine-resources4733748
Node: archive-storage-engine4734168
Node: csv-storage-engine4740329
Node: se-csv-repair4742465
Node: se-csv-limitations4745449
Node: blackhole-storage-engine4746009
Node: ha-overview4749448
Ref: ha-availability-comparison4760640
Node: ha-drbd4763163
Ref: ha-drbd-overview4764713
Node: ha-drbd-install4765743
Node: ha-drbd-install-os4769833
Node: ha-drbd-install-drbd4775943
Node: ha-drbd-install-drbd-primary4778930
Node: ha-drbd-install-drbd-secondary4784324
Node: ha-drbd-install-drbd-using4786437
Node: ha-drbd-install-drbd-management4788836
Node: ha-drbd-install-drbd-othercfg4790634
Node: ha-drbd-install-mysql4792481
Node: ha-drbd-performance4795015
Ref: ha-drbd-performance-sepinterface4795976
Node: ha-drbd-performance-bonded4796569
Node: ha-drbd-performance-syncrate4802515
Node: ha-heartbeat4806156
Ref: ha-heartbeat-overview4808271
Node: ha-heartbeat-config4809490
Node: ha-heartbeat-drbd4814054
Node: ha-heartbeat-drbd-dopd4818624
Node: ha-heartbeat-errors4821337
Node: ha-vm4822663
Node: ha-vm-commonissues4829197
Node: ha-vm-commonissues-performance4830849
Node: ha-vm-commonissues-storage4834578
Node: ha-vm-commonissues-networking4837017
Node: ha-vm-aws4838198
Node: ha-vm-aws-setup4841604
Node: ha-vm-aws-instance4845631
Node: ha-vm-aws-deploy4847659
Node: ha-vm-resources4851949
Node: ha-zfs-replication4852494
Node: ha-zfs-config4858237
Node: ha-zfs-mysql4861564
Node: ha-zfs-mysql-recovery4863223
Node: ha-memcached4865063
Ref: ha-memcached-fig-overview4867159
Node: ha-memcached-install4868610
Node: ha-memcached-using4871934
Node: ha-memcached-using-deployment4879751
Node: ha-memcached-using-namespaces4882101
Node: ha-memcached-using-expiry4883542
Node: ha-memcached-using-hashtypes4885803
Node: ha-memcached-using-dtrace4890942
Node: ha-memcached-using-memory4899127
Ref: ha-memcached-fig-slabs4901366
Node: ha-memcached-using-threads4903300
Node: ha-memcached-interfaces4905099
Ref: ha-memcached-fig-basicflow4907023
Node: ha-memcached-interfaces-libmemcached4910003
Node: ha-memcached-interfaces-libmemcached-base4914176
Node: ha-memcached-interfaces-libmemcached-servers4915347
Node: ha-memcached-interfaces-libmemcached-set4918683
Node: ha-memcached-interfaces-libmemcached-get4923763
Node: ha-memcached-interfaces-libmemcached-behaviors4928379
Node: ha-memcached-interfaces-libmemcached-utilities4932532
Node: ha-memcached-interfaces-perl4934394
Node: ha-memcached-interfaces-python4941145
Node: ha-memcached-interfaces-php4947291
Node: ha-memcached-interfaces-ruby4954648
Node: ha-memcached-interfaces-java4957441
Node: ha-memcached-interfaces-mysqludf4961317
Node: ha-memcached-interfaces-protocol4968211
Node: ha-memcached-interfaces-protocol-tcp4968688
Ref: ha-memcached-interfaces-protocol-responses4978121
Node: ha-memcached-stats4979628
Node: ha-memcached-stats-general4985072
Node: ha-memcached-stats-slabs4989034
Node: ha-memcached-stats-items4992042
Node: ha-memcached-stats-sizes4993848
Node: ha-memcached-faq4995148
Ref: qandaitem-14-5-5-1-14999307
Ref: qandaitem-14-5-5-1-25000113
Ref: qandaitem-14-5-5-1-35000470
Ref: qandaitem-14-5-5-1-45001138
Ref: qandaitem-14-5-5-1-55001705
Ref: qandaitem-14-5-5-1-65002255
Ref: qandaitem-14-5-5-1-75002482
Ref: qandaitem-14-5-5-1-85002790
Ref: qandaitem-14-5-5-1-95003060
Ref: qandaitem-14-5-5-1-105004703
Ref: qandaitem-14-5-5-1-115005041
Ref: qandaitem-14-5-5-1-125006032
Ref: qandaitem-14-5-5-1-135006736
Ref: qandaitem-14-5-5-1-145006965
Ref: qandaitem-14-5-5-1-155007205
Ref: qandaitem-14-5-5-1-165008204
Ref: qandaitem-14-5-5-1-175008954
Ref: qandaitem-14-5-5-1-185010538
Ref: qandaitem-14-5-5-1-195010734
Ref: qandaitem-14-5-5-1-205011341
Ref: qandaitem-14-5-5-1-215011673
Ref: qandaitem-14-5-5-1-225012251
Ref: qandaitem-14-5-5-1-235012587
Ref: qandaitem-14-5-5-1-245012964
Ref: qandaitem-14-5-5-1-255013537
Ref: qandaitem-14-5-5-1-265013815
Ref: qandaitem-14-5-5-1-275014409
Ref: qandaitem-14-5-5-1-285014898
Ref: qandaitem-14-5-5-1-295014960
Ref: qandaitem-14-5-5-1-305015659
Node: mysql-proxy5015974
Node: mysql-proxy-platforms5018427
Node: mysql-proxy-install5019242
Node: mysql-proxy-install-binary5020268
Node: mysql-proxy-install-source5020822
Node: mysql-proxy-install-svn5022355
Node: mysql-proxy-cmdline5024069
Node: mysql-proxy-scripting5028359
Node: mysql-proxy-scripting-injection5033106
Node: mysql-proxy-scripting-structures5035928
Ref: mysql-proxy-scripting-structures-proxy5036581
Ref: mysql-proxy-scripting-structures-connection5037631
Ref: mysql-proxy-scripting-structures-backends5038092
Ref: mysql-proxy-scripting-structures-queries5038905
Ref: mysql-proxy-scripting-structures-response5040318
Ref: mysql-proxy-scripting-structures-resultset5043272
Ref: mysql-proxy-scripting-structures-return-states5045247
Ref: mysql-proxy-scripting-structures-packet-states5046070
Ref: mysql-proxy-scripting-structures-backend-states5046407
Ref: mysql-proxy-scripting-structures-command-constants5047062
Ref: mysql-proxy-scripting-structures-type-constants5048666
Node: mysql-proxy-scripting-connect-server5049900
Node: mysql-proxy-scripting-read-handshake5051395
Node: mysql-proxy-scripting-read-auth5053332
Node: mysql-proxy-scripting-read-auth-result5054969
Node: mysql-proxy-scripting-read-query5056149
Node: mysql-proxy-scripting-read-query-result5059583
Node: mysql-proxy-using5063925
Node: mysql-proxy-using-admin5066435
Node: mysql-proxy-faq5068468
Ref: qandaitem-14-6-6-1-15073437
Ref: qandaitem-14-6-6-1-25073666
Ref: qandaitem-14-6-6-1-35074021
Ref: qandaitem-14-6-6-1-45074333
Ref: qandaitem-14-6-6-1-55074580
Ref: qandaitem-14-6-6-1-65074755
Ref: qandaitem-14-6-6-1-75074944
Ref: qandaitem-14-6-6-1-85075184
Ref: qandaitem-14-6-6-1-95075425
Ref: qandaitem-14-6-6-1-105075829
Ref: qandaitem-14-6-6-1-115076127
Ref: qandaitem-14-6-6-1-125076321
Ref: qandaitem-14-6-6-1-135076517
Ref: qandaitem-14-6-6-1-145076721
Ref: qandaitem-14-6-6-1-155076904
Ref: qandaitem-14-6-6-1-165077179
Ref: qandaitem-14-6-6-1-175077384
Ref: qandaitem-14-6-6-1-185077667
Ref: qandaitem-14-6-6-1-195077950
Ref: qandaitem-14-6-6-1-205078183
Ref: qandaitem-14-6-6-1-215078424
Ref: qandaitem-14-6-6-1-225078762
Ref: qandaitem-14-6-6-1-235079391
Ref: qandaitem-14-6-6-1-245079707
Ref: qandaitem-14-6-6-1-255080038
Ref: qandaitem-14-6-6-1-265080253
Ref: qandaitem-14-6-6-1-275080426
Ref: qandaitem-14-6-6-1-285080689
Ref: qandaitem-14-6-6-1-295081026
Ref: qandaitem-14-6-6-1-305081202
Ref: qandaitem-14-6-6-1-315081572
Ref: qandaitem-14-6-6-1-325081911
Ref: qandaitem-14-6-6-1-335082119
Ref: qandaitem-14-6-6-1-345082335
Ref: qandaitem-14-6-6-1-355082463
Ref: qandaitem-14-6-6-1-365082759
Ref: qandaitem-14-6-6-1-375082879
Ref: qandaitem-14-6-6-1-385083179
Node: mem-introduction5083423
Node: mem-overview5086471
Ref: fig-mem-overview5087332
Node: mem-service-architecture5087617
Node: mem-features5091826
Node: mem-security5094318
Node: mem-conventions5095661
Node: mem-install5100107
Node: mem-user-roles5103929
Node: mem-existing-users5104704
Node: mem-created-users5105480
Node: mem-users-created-first-login5106840
Node: mem-install-server5107739
Node: mem-server-install-generic5110166
Node: mem-server-install-windows5113137
Ref: fig-monitor-install-win15114222
Ref: fig-monitor-install-win35114956
Ref: fig-monitor-install-win45115245
Ref: fig-monitor-install-win55115809
Node: mem-server-install-osx5117011
Ref: fig-monitor-install-osx15119024
Ref: fig-monitor-install-osx25119393
Ref: fig-monitor-install-osx45120136
Ref: fig-monitor-install-osx55120422
Ref: fig-monitor-install-osx65120848
Node: mem-server-install-unix5122077
Node: mem-server-starting-windows5128586
Node: mem-server-starting-unix-osx5131633
Node: mem-server-initial-config5134906
Node: mem-first-login-dashboard5136488
Ref: fig-first-dashboard-login5136831
Node: mem-localization5139562
Node: mem-advisor-installation-after-login5140742
Node: mem-upgrading-updating-advisors5142223
Node: mem-outgoing-email-settings5142913
Ref: fig-email-settings5143579
Node: mem-install-agent5144383
Node: mem-agent-rights5145475
Node: mem-install-agent-windows5149121
Ref: fig-agent-install-win15150122
Ref: fig-agent-install-win35150539
Ref: fig-agent-install-win45152002
Ref: fig-agent-install-win55152831
Ref: fig-agent-install-win65153378
Node: mem-install-agent-osx5154560
Ref: fig-agent-install-osx15155105
Ref: fig-agent-install-osx35157316
Ref: fig-agent-install-osx45158085
Ref: fig-agent-install-osx55158543
Ref: fig-agent-install-osx65159383
Ref: fig-agent-install-osx75159931
Node: mem-install-agent-unix5161110
Node: agent-starting-stopping5171309
Node: mem-starting-agent-windows5172280
Node: mem-starting-agent-osx5175137
Node: mem-starting-agent-unix5178763
Node: mem-advanced-agent-configuration5182451
Node: mem-cfg-mysql-monitor-agent-ini5184808
Ref: mem-log-error-levels5187343
Node: mem-cfg-agent-ini5192579
Node: mem-install-agent-multiple5194620
Node: mem-install-agent-remote5200922
Node: mem-ssh-tunnel5203041
Node: mem-install-new-uuid5204953
Node: mem-troubleshooting-agent-start5205901
Node: mem-unattended-installation5211080
Node: mem-command-line-options-monitoring5212595
Node: mem-command-line-options-server5213158
Node: mem-command-line-options-service-agent5216299
Node: mem-unattended-windows5219601
Node: mem-unattended-unix-osx5221892
Node: mem-unattended-install-starting-services5224437
Node: mem-install-post-installation5225118
Node: mem-upgradeorchange5227704
Node: mem-upgrading5228548
Node: mem-upgrading-2.05232595
Node: mem-upgrading-2.0-server5234062
Ref: fig-monitor-update-install-15235819
Ref: fig-monitor-update-install-35236287
Ref: fig-monitor-update-install-45236575
Ref: fig-monitor-update-install-75237847
Ref: fig-monitor-update-install-95238491
Node: mem-upgrading-2.0-agent5238779
Node: mem-unattended-update5243768
Node: mem-reinstalling-mysqlmonitor5245784
Node: mem-changing-installation5246719
Node: mem-ungrading-monitored-server5247299
Node: mem-changing-monitored-server5248353
Node: mem-suspending-agent5250625
Node: mem-uninstall5252439
Node: mem-windows-removal5253147
Node: mem-remove-windows5253529
Node: mem-remove-windows-services5254869
Node: mem-removing-agent-windows5256246
Node: mem-remove-single-agent-windows5257499
Node: mem-unix-osx-removal5258881
Node: mem-remove-unix-osx5259269
Node: mem-removing-service-agent-unix-osx5260538
Node: mem-remove-agent-unix-osx5261541
Node: mem-deployment5262713
Node: mem-deployment-backup5263804
Node: mem-deployment-migration-2-05266321
Ref: fig-monitor-migration-check5268958
Ref: fig-monitor-migration-confirm5269729
Ref: monitor-migration-progress5270036
Node: mem-deployment-maintenance5272515
Node: mem-deployment-config5273380
Node: mem-dashboard5274334
Node: mem-server-tree5281553
Node: mem-monitor-page-graphs5282534
Ref: mem-server-graphs5282839
Ref: mem-graph-interval5284552
Node: mem-heat-chart5284852
Ref: fig-mem-heat-chart5285552
Ref: fig-mem-heat-chart-legend5285669
Node: mem-dashboard-settings5286841
Node: mem-global-settings5288221
Ref: fig-mem-settings-global5288604
Ref: mem-snmp-traps5289291
Ref: mem-data-purge5291762
Node: mem-user-preferences5296348
Ref: fig-mem-settings-user5296617
Node: mem-managing-servers5297431
Ref: fig-mem-settings-servers5298232
Node: mem-server-rename5298881
Ref: fig-mem-server-rename5299752
Node: mem-server-grouping5299815
Node: mem-deleting-mysql-server5301512
Node: mem-managing-users5302790
Ref: fig-mem-settings-users5303107
Node: mem-notification-groups5305637
Ref: fig-mem-settings-notification5305993
Node: mem-logs5307006
Ref: fig-mem-settings-logs5307313
Node: mem-product-info5309097
Node: mem-subscriptions-warning5311073
Node: mem-advisors5312601
Node: mem-update-advisors5315996
Node: mem-scheduling-rules5316840
Ref: fig-mem-usage-advisor-configuration5318983
Node: mem-heat-chart-notifications5322415
Node: mem-editing-built-in-rules5323756
Ref: fig-mem-edit-advisor5324158
Node: mem-creating-advisors-and-rules5328430
Node: mem-creating-advisors5329332
Node: mem-creating-rules-overview5330225
Node: mem-advisors-variables5333478
Node: mem-advisors-thresholds5334776
Node: mem-advisors-using-strings5338103
Node: mem-advisors-wiki-format5339214
Node: mem-example-creating-rule5341448
Node: mem-custom-data-collection-item5344369
Node: mem-custom-data-item-xml-file5345272
Node: mem-unscheduling-advisors5347292
Node: mem-advisor-blackouts5349274
Node: mem-advisor-scripting-blackouts5351561
Node: mem-events5353972
Ref: mem-events-screen5355132
Node: mem-closing-events5357917
Node: mem-graphs5358780
Node: mem-available-graphs5360670
Node: mem-setting-graph-interval5361497
Node: mem-setting-graph-time-span5362579
Node: mem-query-analysis5364000
Ref: fig-mem-quan-main5369345
Node: mem-query-analysis-enabling5374024
Node: mem-query-analysis-enabling-app5380202
Ref: fig-mem-quan-layout15380795
Ref: fig-mem-quan-layout25380961
Node: mem-query-analysis-enabling-mysql5383441
Node: mem-query-analysis-queries5384804
Ref: fig-mem-quan-item-summary5385774
Ref: fig-mem-quan-item-example5387404
Ref: fig-mem-quan-item-explain5387851
Node: mem-query-analysis-filtering5388103
Node: mem-query-analysis-using5392088
Node: mem-query-analysis-troubleshooting5394121
Node: mem-query-analysis-settings5398032
Ref: fig-mem-quan-config5398571
Node: mem-replication5401934
Ref: fig-mem-replication5403302
Node: mem-replication-details5404173
Node: mem-faq5406740
Ref: mem-faq-general5407351
Ref: qandaitem-15-12-1-15409457
Ref: qandaitem-15-12-1-25410694
Ref: qandaitem-15-12-1-35410923
Ref: qandaitem-15-12-1-45411288
Ref: qandaitem-15-12-1-55412121
Ref: qandaitem-15-12-1-65412401
Ref: qandaitem-15-12-1-75412772
Ref: qandaitem-15-12-1-85412935
Ref: qandaitem-15-12-1-95413281
Ref: qandaitem-15-12-1-105413606
Ref: qandaitem-15-12-1-115415108
Ref: qandaitem-15-12-1-125415439
Ref: qandaitem-15-12-1-135415795
Ref: qandaitem-15-12-1-145415930
Ref: mem-faq-enterprise5416395
Ref: qandaitem-15-12-2-15417971
Ref: qandaitem-15-12-2-25418412
Ref: qandaitem-15-12-2-35419013
Ref: qandaitem-15-12-2-45419233
Ref: qandaitem-15-12-2-55419583
Ref: qandaitem-15-12-2-65419897
Ref: qandaitem-15-12-2-75420262
Ref: qandaitem-15-12-2-85420713
Ref: qandaitem-15-12-2-95420986
Ref: qandaitem-15-12-2-105421192
Ref: qandaitem-15-12-2-115421455
Ref: qandaitem-15-12-2-125422316
Ref: qandaitem-15-12-2-135422677
Ref: qandaitem-15-12-2-145422999
Ref: qandaitem-15-12-2-155423286
Ref: qandaitem-15-12-2-165423727
Ref: qandaitem-15-12-2-175424063
Ref: qandaitem-15-12-2-185424236
Ref: qandaitem-15-12-2-195424481
Ref: qandaitem-15-12-2-205424768
Ref: qandaitem-15-12-2-215424948
Ref: qandaitem-15-12-2-225425188
Ref: mem-faq-monitor5425821
Ref: qandaitem-15-12-3-15427225
Ref: qandaitem-15-12-3-25427746
Ref: qandaitem-15-12-3-35427912
Ref: qandaitem-15-12-3-45428165
Ref: qandaitem-15-12-3-55428604
Ref: qandaitem-15-12-3-65429302
Ref: qandaitem-15-12-3-75430591
Ref: qandaitem-15-12-3-85431078
Ref: qandaitem-15-12-3-95431495
Ref: qandaitem-15-12-3-105432051
Ref: qandaitem-15-12-3-115432742
Ref: qandaitem-15-12-3-125434074
Ref: qandaitem-15-12-3-135434298
Ref: qandaitem-15-12-3-145434809
Ref: qandaitem-15-12-3-155435254
Ref: mem-faq-queryanalyzer5435552
Ref: qandaitem-15-12-4-15436306
Ref: qandaitem-15-12-4-25436950
Ref: qandaitem-15-12-4-35437491
Ref: qandaitem-15-12-4-45437783
Ref: qandaitem-15-12-4-55438018
Ref: qandaitem-15-12-4-65438822
Ref: qandaitem-15-12-4-75439209
Ref: qandaitem-15-12-4-85439611
Ref: qandaitem-15-12-4-95439903
Node: replication5440182
Node: replication-configuration5444945
Node: replication-howto5448727
Node: replication-howto-repuser5453033
Node: replication-howto-masterbaseconfig5454680
Node: replication-howto-slavebaseconfig5456442
Node: replication-howto-masterstatus5458021
Node: replication-howto-mysqldump5461562
Node: replication-howto-rawdata5463744
Node: replication-howto-newservers5467501
Node: replication-howto-existingdata5469416
Node: replication-howto-additionalslaves5473933
Node: replication-howto-slaveinit5477687
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Node: replication-sbr-rbr5483194
Node: replication-rbr-usage5492642
Node: replication-options5499531
Ref: option_mysqld_server-id5500593
Node: replication-options-table5501717
Node: replication-options-master5535372
Ref: sysvar_auto_increment_increment5536364
Ref: sysvar_auto_increment_offset5544227
Node: replication-options-slave5544808
Ref: replication-optvars-slaves5548504
Ref: option_mysqld_log-slave-updates5548927
Ref: option_mysqld_log-slow-slave-statements5549881
Ref: option_mysqld_master-info-file5551035
Ref: option_mysqld_master-retry-count5551232
Ref: option_mysqld_max-relay-log-size5551862
Ref: option_mysqld_read-only5552052
Ref: option_mysqld_relay-log5552386
Ref: option_mysqld_relay-log-index5553887
Ref: option_mysqld_relay-log-info-file5554931
Ref: option_mysqld_relay-log-purge5555138
Ref: option_mysqld_relay-log-recovery5555412
Ref: option_mysqld_relay-log-space-limit5555838
Ref: option_mysqld_replicate-do-db5557056
Ref: option_mysqld_replicate-ignore-db5561668
Ref: option_mysqld_replicate-do-table5564099
Ref: option_mysqld_replicate-ignore-table5564429
Ref: option_mysqld_replicate-rewrite-db5564869
Ref: option_mysqld_replicate-same-server-id5565864
Ref: option_mysqld_replicate-wild-do-table5566616
Ref: option_mysqld_replicate-wild-ignore-table5568412
Ref: option_mysqld_report-host5569213
Ref: option_mysqld_report-password5569836
Ref: option_mysqld_report-port5570133
Ref: option_mysqld_report-user5570491
Ref: option_mysqld_show-slave-auth-info5570786
Ref: option_mysqld_skip-slave-start5571037
Ref: option_mysqld_slave_compressed_protocol5571238
Ref: option_mysqld_slave-load-tmpdir5571451
Ref: option_mysqld_slave-net-timeout5572678
Ref: option_mysqld_slave-skip-errors5573234
Ref: option_mysqld_sql_slave_skip_counter5574791
Ref: option_mysqld_abort-slave-event-count5575428
Ref: option_mysqld_disconnect-slave-event-count5576461
Ref: replication-optvars-slaves-obsolete5576801
Ref: replication-sysvars-slaves5577487
Ref: sysvar_init_slave5577769
Ref: sysvar_rpl_recovery_rank5578641
Ref: sysvar_relay_log_recovery5578699
Ref: sysvar_sync_master_info5579242
Ref: sysvar_sync_relay_log5580266
Ref: sysvar_sync_relay_log_info5581593
Ref: sysvar_slave_compressed_protocol5582658
Ref: option_mysqld_slave_exec_mode5583227
Ref: sysvar_slave_load_tmpdir5583997
Ref: option_mysqld_slave_net_timeout5584560
Ref: sysvar_slave_skip_errors5585255
Ref: option_mysqld_slave_transaction_retries5585904
Node: replication-options-binary-log5586993
Ref: replication-optvars-binlog5587635
Ref: option_mysqld_binlog-row-event-max-size5588042
Ref: option_mysqld_log-bin5588746
Ref: option_mysqld_log-bin-index5589642
Ref: option_mysqld_binlog-do-db5590291
Ref: option_mysqld_binlog-ignore-db5594990
Ref: option_mysqld_log-bin-trust-function-creators5597792
Ref: option_mysqld_max-binlog-dump-events5598817
Ref: option_mysqld_sporadic-binlog-dump-fail5599144
Ref: replication-sysvars-binlog5599500
Ref: sysvar_binlog_cache_size5599780
Ref: sysvar_binlog_format5601198
Ref: sysvar_max_binlog_cache_size5603444
Ref: sysvar_max_binlog_size5604450
Ref: sysvar_sync_binlog5605527
Node: replication-administration5606926
Node: replication-administration-status5607746
Node: replication-administration-pausing5613113
Node: replication-solutions5615065
Node: replication-solutions-backups5617495
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Node: replication-solutions-backups-rawdata5622052
Node: replication-solutions-backups-read-only5624755
Node: replication-solutions-diffengines5628649
Node: replication-solutions-scaleout5632612
Ref: figure_replication-scaleout5633798
Node: replication-solutions-partitioning5635786
Ref: figure_replication-multi-db5636402
Node: replication-solutions-performance5638599
Ref: figure_replication-performance5639755
Node: replication-solutions-switch5642007
Ref: figure_replication-redundancy-before5643608
Ref: figure_replication-redundancy-after5646775
Node: replication-solutions-multi-master-upgrade5648117
Node: replication-solutions-ssl5661196
Node: replication-semisync5664878
Node: replication-semisync-interface5670373
Node: replication-semisync-installation5672789
Node: replication-semisync-monitoring5677828
Node: replication-notes5679692
Node: replication-features5680293
Node: replication-features-auto-increment5684646
Node: replication-features-charset5687789
Node: replication-features-create-select5690089
Node: replication-features-differing-tables5692430
Node: replication-features-more-columns5693664
Node: replication-features-different-data-types5697130
Node: replication-features-directory5702913
Node: replication-features-drop-if-exists5703913
Node: replication-features-invoked5704882
Node: replication-features-floatvalues5709914
Node: replication-features-flush5710792
Node: replication-features-functions5712234
Node: replication-features-limit5716723
Node: replication-features-load-data5717940
Node: replication-features-logging5718773
Node: replication-features-mastercrash5719245
Node: replication-features-mastershutdown5719940
Node: replication-features-memory5721018
Node: replication-features-mysqldb5721708
Node: replication-features-optimizer5722449
Node: replication-features-reserved-words5723213
Node: replication-features-slaveerrors5725277
Node: replication-features-slaveshutdown5726146
Node: replication-features-temptables5726844
Node: replication-features-timeout5729088
Node: replication-features-timezone5730059
Node: replication-features-transactions5731087
Node: replication-features-triggers5735750
Node: replication-features-truncate5737485
Node: replication-features-variables5738616
Node: replication-features-views5739834
Node: replication-compatibility5740427
Node: replication-upgrade5743928
Node: replication-faq5746027
Ref: qandaitem-16-3-4-1-15747996
Ref: qandaitem-16-3-4-1-25748814
Ref: qandaitem-16-3-4-1-35749140
Ref: qandaitem-16-3-4-1-45750243
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Ref: qandaitem-16-3-4-1-115757666
Ref: qandaitem-16-3-4-1-125757785
Ref: qandaitem-16-3-4-1-135757993
Ref: qandaitem-16-3-4-1-145758149
Node: replication-problems5758316
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Node: partitioning5792525
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Node: stored-routines-last-insert-id5941204
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Ref: events-event-scheduler-option5959113
Node: events-syntax5964720
Node: events-metadata5965724
Node: events-status-info5966246
Node: events-privileges5968473
Node: views5976481
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Node: view-updatability5982689
Node: view-metadata5988715
Node: stored-programs-logging5989112
Node: information-schema6008709
Node: schemata-table6018630
Node: tables-table6019557
Node: columns-table6022753
Node: statistics-table6025782
Node: user-privileges-table6027979
Node: schema-privileges-table6028967
Node: table-privileges-table6030045
Node: column-privileges-table6031299
Node: character-sets-table6033051
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Node: collation-character-set-applicability-table6035000
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Node: key-column-usage-table6037200
Node: routines-table6039852
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Node: engines-table6055645
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Node: events-table6065037
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Ref: connectors-apis-summary6105968
Ref: connectors-apis-versions6110842
Node: connector-odbc6111783
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Node: connector-odbc-driver-manager6125988
Node: connector-odbc-installation6127708
Node: connector-odbc-installation-binary-windows6131531
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Node: connector-odbc-installation-source-unix-configure-options6154011
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Node: connector-odbc-installation-source-unix-macosx6163671
Node: connector-odbc-installation-source-unix-hpux6165644
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Node: connector-odbc-installation-source-development6167809
Node: connector-odbc-configuration6170179
Node: connector-odbc-configuration-dsn6171625
Node: connector-odbc-configuration-connection-parameters6173054
Node: connector-odbc-configuration-dsn-windows6189140
Node: connector-odbc-configuration-dsn-windows-3-516192741
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Node: connector-odbc-configuration-dsn-windows-problems6199670
Node: connector-odbc-configuration-dsn-macosx6201011
Node: connector-odbc-configuration-dsn-unix6203882
Node: connector-odbc-configuration-connection-without-dsn6205859
Node: connector-odbc-configuration-connection-pooling6207382
Node: connector-odbc-configuration-trace6208153
Node: connector-odbc-configuration-trace-windows6208980
Node: connector-odbc-configuration-trace-macosx6210056
Node: connector-odbc-configuration-trace-unix6210787
Node: connector-odbc-configuration-trace-log6211826
Node: connector-odbc-examples6212924
Node: connector-odbc-examples-overview6214068
Node: connector-odbc-examples-walkthrough6214826
Node: connector-odbc-examples-tools6216982
Node: connector-odbc-examples-tools-with-access6219540
Node: connector-odbc-examples-tools-with-access-export6220403
Node: connector-odbc-examples-tools-with-access-import6222234
Node: connector-odbc-examples-tools-with-access-linked-tables6223482
Node: connector-odbc-examples-tools-with-wordexcel6226971
Node: connector-odbc-examples-tools-with-crystalreports6230195
Node: connector-odbc-examples-programming6234930
Node: connector-odbc-examples-programming-vb6235749
Node: connector-odbc-examples-programming-vb-ado6236474
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Node: connector-odbc-examples-programming-net6244016
Node: connector-odbc-examples-programming-net-csharp6244576
Node: connector-odbc-examples-programming-net-vb6250524
Node: connector-odbc-reference6254507
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Node: connector-odbc-reference-datatypes6266715
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Node: connector-odbc-usagenotes6272933
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Node: connector-odbc-usagenotes-functionality-last-insert-id6274368
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Node: connector-odbc-usagenotes-functionality-performance6276537
Node: connector-odbc-usagenotes-functionality-query-timeout6278132
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Ref: qandaitem-20-1-7-3-1-16304162
Ref: qandaitem-20-1-7-3-1-26305154
Ref: qandaitem-20-1-7-3-1-36305503
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Ref: qandaitem-20-1-7-3-1-226315317
Ref: qandaitem-20-1-7-3-1-236315615
Node: connector-odbc-support6316185
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Node: connector-net-examples-mysqlcommand-parameters6369550
Node: connector-net-examples-mysqlcommand-transaction6371853
Node: connector-net-examples-mysqlcommand-updatedrowsource6372691
Node: connector-net-examples-mysqlcommandbuilder6373352
Node: connector-net-examples-mysqlcommandbuilder-ctor6379414
Node: connector-net-examples-mysqlcommandbuilder-ctor16379809
Node: connector-net-examples-mysqlcommandbuilder-ctor26380816
Node: connector-net-examples-mysqlcommandbuilder-ctor36381640
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Node: connector-net-examples-mysqlcommandbuilder-quoteprefix6383793
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Node: connector-net-examples-mysqlcommandbuilder-getdeletecommand6385560
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Node: connector-net-examples-mysqlcommandbuilder-getupdatecommand6388184
Node: connector-net-examples-mysqlcommandbuilder-refreshschema6389491
Node: connector-net-examples-mysqlconnection6390467
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Node: connector-net-examples-mysqlconnection-ctor16395358
Node: connector-net-examples-mysqlconnection-connectionstring6396543
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Node: connector-net-examples-mysqlconnection-createcommand6426351
Node: connector-net-examples-mysqlconnection-begintransaction6426779
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Node: connector-net-examples-mysqldataadapter6441683
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Node: connector-net-examples-mysqldataadapter-ctor36457609
Node: connector-net-examples-mysqldataadapter-deletecommand6461355
Node: connector-net-examples-mysqldataadapter-insertcommand6464334
Node: connector-net-examples-mysqldataadapter-updatecommand6467574
Node: connector-net-examples-mysqldataadapter-selectcommand6471067
Node: connector-net-examples-mysqldatareader6473713
Node: connector-net-examples-mysqldatareader-getbytes6477921
Node: connector-net-examples-mysqldatareader-gettimespan6478883
Node: connector-net-examples-mysqldatareader-getdatetime6479339
Node: connector-net-examples-mysqldatareader-getmysqldatetime6480326
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Node: connector-net-examples-mysqldatareader-getfloat6482196
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Ref: qandaitem-20-3-4-1-1-16912068
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Ref: qandaitem-20-4-5-3-1-17108405
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End Tag Table
